WO2024015553A1 - Fine denier rubber filaments comprising natural rubber and methods for making them - Google Patents

Fine denier rubber filaments comprising natural rubber and methods for making them Download PDF

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Publication number
WO2024015553A1
WO2024015553A1 PCT/US2023/027738 US2023027738W WO2024015553A1 WO 2024015553 A1 WO2024015553 A1 WO 2024015553A1 US 2023027738 W US2023027738 W US 2023027738W WO 2024015553 A1 WO2024015553 A1 WO 2024015553A1
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WIPO (PCT)
Prior art keywords
filament
rubber
natural rubber
latex
fiber
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PCT/US2023/027738
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French (fr)
Inventor
Stephen James MITCHELL
Jeff A. MARTIN
Liz BUI
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Yulex Llc
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Publication of WO2024015553A1 publication Critical patent/WO2024015553A1/en

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Classifications

    • D—TEXTILES; PAPER
    • D02—YARNS; MECHANICAL FINISHING OF YARNS OR ROPES; WARPING OR BEAMING
    • D02G—CRIMPING OR CURLING FIBRES, FILAMENTS, THREADS, OR YARNS; YARNS OR THREADS
    • D02G3/00—Yarns or threads, e.g. fancy yarns; Processes or apparatus for the production thereof, not otherwise provided for
    • D02G3/22—Yarns or threads characterised by constructional features, e.g. blending, filament/fibre
    • D—TEXTILES; PAPER
    • D02—YARNS; MECHANICAL FINISHING OF YARNS OR ROPES; WARPING OR BEAMING
    • D02G—CRIMPING OR CURLING FIBRES, FILAMENTS, THREADS, OR YARNS; YARNS OR THREADS
    • D02G3/00—Yarns or threads, e.g. fancy yarns; Processes or apparatus for the production thereof, not otherwise provided for
    • D02G3/22—Yarns or threads characterised by constructional features, e.g. blending, filament/fibre
    • D02G3/32—Elastic yarns or threads ; Production of plied or cored yarns, one of which is elastic
    • D—TEXTILES; PAPER
    • D02—YARNS; MECHANICAL FINISHING OF YARNS OR ROPES; WARPING OR BEAMING
    • D02G—CRIMPING OR CURLING FIBRES, FILAMENTS, THREADS, OR YARNS; YARNS OR THREADS
    • D02G3/00—Yarns or threads, e.g. fancy yarns; Processes or apparatus for the production thereof, not otherwise provided for
    • D02G3/22—Yarns or threads characterised by constructional features, e.g. blending, filament/fibre
    • D02G3/38—Threads in which fibres, filaments, or yarns are wound with other yarns or filaments, e.g. wrap yarns, i.e. strands of filaments or staple fibres are wrapped by a helically wound binder yarn
    • D—TEXTILES; PAPER
    • D02—YARNS; MECHANICAL FINISHING OF YARNS OR ROPES; WARPING OR BEAMING
    • D02G—CRIMPING OR CURLING FIBRES, FILAMENTS, THREADS, OR YARNS; YARNS OR THREADS
    • D02G3/00—Yarns or threads, e.g. fancy yarns; Processes or apparatus for the production thereof, not otherwise provided for
    • D02G3/22—Yarns or threads characterised by constructional features, e.g. blending, filament/fibre
    • D02G3/36—Cored or coated yarns or threads

Definitions

  • This invention relates to polymer chemistry and natural products and uses and applications thereof.
  • provided are spandex -like fibers for filaments derived from natural rubber and/or purified natural rubber latex.
  • provided are methods of making composite yarns and fabrics from the fibers/filaments.
  • Fibers are referred to as staple fibers that have a length between 2-46 cm. Fibres are natural or man-made, and man-made fibres are further categorized into organic and inorganic fibres.
  • the Bureau International for Standardization of Fibres Artificielles (BISFA) defines or characterizes fibers by their flexibility, fineness, and high ratio of length to cross sectional area. Filaments on the other hand, have infinite length or of very great length or of a continuous length.
  • Natural rubber filaments in this invention were also referred to as natural rubber threads, for example, in priority applications, which is a more common textile industry term, but the more correct term is a natural rubber fibre, in particularly a natural rubber filament describing a continuous monofilament of the invention.
  • Natural rubber filaments are commonly used in a number of products, including but not limited to elasticized fabrics for textile applications. It has long been produced in industry as an elastic filament in clothing such as socks, underpants and shirts and is produced by extruding wet liquid latex into an acid bath, which coagulates the rubber, forming a solid material with high elongation and return to original shape.
  • rubber filaments came in two forms, bare rubber or covered rubber, the latter having a rubber core and wrapped or braided with thread or yam.
  • Rubber filaments is produced by simply slicing thin ribbons of cured and colored rubber sheets. The rubber sheet is pulled across a series of knife blades slicing thin strips from the flat ribbon, which were then wound up on an uptake bobbin.
  • one of the main disadvantages was that the core size or diameter was rarely uniform to each other throughout the length of a thread and were often square because they were simply cut from a rubber sheet or ribbon.
  • spandex is produced by wet or dry spinning of a combination of polymers containing both long and short polymer chains in varying percentages to suit the desired thread properties. Chemically, it is made up of a long-chain polyglycol combined with a short di- isocyanate and contains at least 85% polyurethane (PU). It is distinguished from the natural rubber filaments described herein because spandex fibers are made up of numerous (more than one or multi) polymer strands consisting of long, amorphous segments and short, rigid segments.
  • natural rubber fibers and/or filaments and/or equivalents thereof from natural rubber latex, purified natural rubber latex or purified natural solid rubber (or cis- 1 , 4 polyisoprene) that are exceptionally consistent, uniform, and unambiguous physical properties. See Table 1.
  • Purified elastomeric natural rubber solid or latex form is a purified rubber that during production has had over 98% to 99.9% of natural rubber harmful impurities, including proteins and other non-rubber content removed or “purified”.
  • the PENR has increased performance characteristics and physical properties over existing commercial crude natural rubber latex including but not limited to higher total rubber content, substantially no or de minimus levels of non-rubber content or contaminants including proteins, improved green strength, improved tensile strength, improved viscosity, improved elongation modulus, improved heat and UV stability and the like.
  • a rubber fiber/filament made from or derived from such a high-performance rubber latex source material such as PENR will also produce equally uniform, consistent, and high-performance rubber products with similar physical properties.
  • Embodiments of the invention include:
  • a rubber filament [0014]
  • the filament is made from purified natural rubber latex that is free (or substantially free) of more than 90% of non-rubber content; wherein the filament is made from purified natural rubber latex that is free of about 90% of proteins, or are free of between about 1% to 98% of proteins, or are free of between about 5% to 95% of proteins, or are free of between about 10% to 90% of proteins; wherein the filament is made from purified natural rubber latex that has reduced (or between about 1% to 90% lower, or between about 10% to 80% lower) levels of latex allergenic proteins; wherein the filament is made from purified natural rubber latex that has reduced (or between about 1% to 90% lower, or between about 10% to 80% lower) levels of latex allergenic proteins; wherein the filament is made from purified natural rubber latex that has reduced (or between about 1% to 90% lower, or between
  • a rubber filament comprising any method of extruding the filament from a purified natural rubber latex substantially free of non-rubber content; or comprising extruding or electrospinning the filament from a purified natural rubber latex substantially free of latex proteins; or comprising a filament made from 10% to 90% prevulcanized natural rubber latex, or between about 20% to 95% prevulcanized natural rubber latex.
  • woven and knitted textiles comprising an elasticized yam as provided herein, or a rubber filament as provided herein.
  • a fine natural rubber filament that is about 120 to 160 count or 317 to 178 denier.
  • a natural rubber filament comprising less than about 80% natural rubber or content.
  • a natural rubber filament comprising less than about 75% natural rubber content.
  • a natural rubber filament comprising filaments as provided herein, wherein the natural rubber is cis-1, 4 polyisoprene.
  • the natural rubber filament of filaments as provided herein, wherein the filament is made from purified natural rubber latex that is free of more than 90% of non-rubber content.
  • the natural rubber filament of filaments as provided herein, wherein the filament is made from purified natural rubber latex that is free of 90% of proteins.
  • a method for making a natural rubber filament as of the filaments above comprising any method of extruding the filament from a purified natural rubber latex substantially free of non-rubber content.
  • a method for making an elasticized yarn from any of the natural rubber filaments as of methods and filaments above comprising ring-spinning, rotorspinning, twistless spinning, wrap-spinning, core-spinning and/or air-jet spinning.
  • advantages of the invention there is provided a method for making a knitted fabric or a knit from elasticized yarns using weft or warp spinning.
  • FIG. 1 is a diagram describing typical natural rubber tree (e.g., Hevea braziliensis) latex emulsion and/or solid production.
  • typical natural rubber tree e.g., Hevea braziliensis
  • FIG. 2 is a diagram describing the 4 principle steps of the purifying natural rubber latex of the present disclosure including obtaining the field latex and treating it with an anionic liquid and basic solution (Step 1); purifying the field latex by high speed centrifugation (Step 2); separating and collecting the heavy and the light phase (Step 3); and final treatment to produce the purified NR latex and / or solid.
  • FIG. 3 is a schematic diagram describing the four principal steps as described in FIG. 2 and principal components of field latex including rubber particles (light grey ovals), impurities dirt and other plant particles or debris (yellow squares), and other impurities such as fats, proteins, metals & oils (dark grey triangles).
  • FIG. 4A-B illustrate images comparing the color and clarity of the purified NRL emulsions (FIG.4A) and solid NR (FIG.4B) as provided herein as compared to other commercially available NRL and solid NR (ribbed smoked sheets of crude Hevea).
  • the purified NRL as provided herein is clearer or colorless as compared to the other un-purified NRL.
  • the purified solid NR is also substantially colorless or light-yellow tint (or off-white) as compared to the ribbed smoked sheets from unpurified NRL.
  • FIG. 5 is a diagram of an exemplary work progress flow.
  • FIG. 6 is a diagram of an exemplary work progression flow decision tree as provided herein.
  • FIG. 7 is a diagram of a process of producing rubber fiber or filament from natural rubber latex.
  • FIG. 8 is a diagram of a process of producing rubber fiber or filament from natural solid rubber.
  • FIG. 9 is a diagram of a process of producing rubber fiber or filament from purified or elastomeric natural rubber latex.
  • FIG. 10 is a diagram of a process of producing rubber fiber or filament from purified natural solid rubber.
  • FIG. 11 is a diagram of exemplars of extruding forming molds.
  • FIG. 12 is another process of producing rubber fiber or filament from purified natural solid rubber.
  • FIG. 13 is a diagram of latex single (A) and multiple (B) extruder head configurations.
  • FIG. 14 are diagrams of cross sections of various rubber fibers or filaments.
  • FIG. 15 is a diagram of a process of producing rubber fiber or filament from purified natural solid rubber using electrospinning technologies.
  • FIG. 16 is cross-section diagram of a hollow natural rubber fibre.
  • FIG. 17 is cross-section diagram of a nano or near-nano natural rubber fibre.
  • FIG. 20 is an image of 200D elastomeric natural rubber fiber of the invention.
  • FIG. 18-19 and 21-28 are diagrams from Sinclair, R. (Ed.) (2014) Textiles and fashion: Materials, design, and technology. Elsevier Science & Technology, Chapter 8-15, which is incorporated in its entirety be referenced and/or adapted to describe embodiments of the present invention. They describe different spun yarns and their applications and drawings of different spinning methods including ring-spinning (Like reference symbols in the various drawings indicate like elements.
  • antioxidant refers to chemicals that are used to protect rubber articles against attack from oxygen (02).
  • antiozonants refers to chemicals and / or waxes that “bleed” to the surface of a rubber article, to protect it against attack from ozone (03), and antiozonant ingredients.
  • antiozonant waxes are added to natural rubber to protect the fiber/filament from ozone by migration and blooming to surface which may also provide an increased level of lubricity.
  • antigenic protein refers to a protein that can induce the generation of antibodies and can cause an immune response in a subject who meets the antigenic protein.
  • biodegradable means microbial degradation of carbon containing materials.
  • continuous vulcanization refers to a process for vulcanizing NRL during continuous passage through specially designed energy transfer equipment.
  • core-spun yarn or “polycore” yam is created by twisting staple natural or synthetic fibres around a central filament core. Different spinning methods can be used to produce a core-spun yam.
  • the term “count” in the textile industry is used to express how fine or coarse (or thin or thick) the yarn is. The numerical value is obtained by measuring how much length there is for a certain weight.
  • count systems including direct, indirect and cotton count systems.
  • Count and Denier are inversely related: when the Count goes up, the Denier goes down and when the Count goes down the Denier goes up.
  • curing also known as “vulcanization,” causes the long polymer chains that rubber is composed of to become cross-linked.
  • the term “dual-core” or “double-core yam” refers to a yarn having three components where a spandex fibre (such as Lycra, Creora and Inviya 1-300) and a multifilament (such as PET, PBT, PA and Lycra® . i o . T400) cores are covered with sheath staple fibers.
  • a dual -core yarn having an elastane or a fine natural rubber filament of the invention, surrounded by multifilament (e.g., LycraT400) and wrapped by sheath cotton fibers will achieve different elasticity and durability of fabrics, e.g., denim fabrics.
  • decitex or “dtex” refers to a metric unit used for continuous filament yarn, defined as the mass in gram per 10,000 m.
  • the term “dimensional stability” refers to a fabric capable of retaining its original dimensions or shape of the fabric while being used for its required purposes (e.g., dyeing, finishing, washing or any other processes).
  • the term “elasticity” refers to the property of rapid recovery of a material to its approximate original shape and dimensions after substantial deformation by a force and subsequent release of that force.
  • the “elastomeric fibres” refers to any fibre or fiber, whether natural or non -natural, that can stretch 300% to 400% or more and return to their original size including but not limited to spandex, lycra and any natural fiber or filament described herein.
  • IUPAC defines the term "elastomer” as a polymer that displays rubber-like elasticity.
  • the term “elongation” refers to the length at breaking point expressed as a percentage of its original length (i.e., length at rest). For example, if a rubber component reaches twice its length before breaking its elongation is 100%; if it reaches three times its length before breaking its elongation is 200%; and if it reaches four times its length before breaking its elongation is 300% and so on.
  • any of the methods described herein and in Figures, 2-19 and Table 5 can be modified adapted to provide for a filament with a desirable elongation factor.
  • the term “fiber” or “fibre” is a basic unit of a material.
  • fiber and filament are interchangeable in context to the natural rubber fibers / filaments of the invention.
  • the term “filament” is a continuous length of interlocking fibers, which can be spun from fibers or filaments and used in textiles for weaving, knitting, or sewing.
  • the invention herein, “filament an” is a long continuous and indefinite monofilament or fiber. This is different from spandex like fibers that are made of twisting or forming together many short fibers or staple fibers to form a longer fiber and are not continuous monofilaments.
  • Inventions here are long mono- fibers/filaments made from natural rubber and the terms “fibre” “fiber” and/or “filament” are used interchangeably.
  • filler refers to materials or particles added to resin or natural or synthetic rubber that can improve specific properties.
  • Non-black fillers for rubber exist including but not limited to calcium carbonate, kaolin clay, Dixie Clay, precipitated silica, talc, barite, wollastonite, mica, precipitated silicates, fumed silica, and diatomite.
  • latex or “natural rubber latex,” “crude rubber latex” or equivalents thereof refers to an “emulsion” or milky liquid, or non-vulcanized rubber, colloidal aqueous dispersion of a polymeric material that is extracted from any of various rubber producing plants and is the source of natural rubber.
  • the term “latex compounding” refers to the addition of the certain chemicals to obtain certain or optimum physical properties in the finished product including but not limited to for example the chemistries to control the colloidal properties, to lower cost of goods, and/or to make it useable for use with available equipment.
  • the term “linear mass density” is the mass per unit length of any a one-dimensional object such as a string, wire, cable or in this invention a natural rubber fiber, it is expressed in kg / m or g / cm.
  • modulus refers to a measure of stiffness under specified conditions of deformation, e.g., compression modulus or shear modulus, whichever applies. Modulus value desired depends on its application, e.g., modulus for a wetsuit will be different than modulus for denim, apparel, footwear, or upper soles of a shoe, for the same textile material.
  • the formulation and method of making the same described herein can form the desired modulus for the desired application and product. It is expressed in Pa (pascals) megapascals, gigapascals, kilopascals, or Newtons (N) square meter, Nm2.
  • non-rubber or “non-rubber content” refers to non-rubber impurities.
  • protein content or “total protein content” refer to the amount of protein in any sample. Warburg-Christian, Lowry Assay, and Bradford Assay, or FITkit® Hev b 6.02 that test certain latex allergens can all identify and/or quantify levels of proteins in an article, e.g., a finished good made from natural rubber.
  • purified natural rubber is a natural rubber latex that has been compounded to obtain certain physical properties or characteristics of a purified or premium NRL is 90% or more purified of contaminants, or about 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% free of other non-rubber contents including proteins or about 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% protein free.
  • the invention provides for a natural rubber fiber that is more than 90% deproteinized.
  • the fibers of the invention have the following physical properties: i) the total range of protein content is about 50 ug/g to about 200ug/g (see Table 2); ii) the total solids content (TSC) range is between at least 60% (see Table 1), depending on the process parameters and the desired TSC level for the process or requirements for a machine or industry or field; iii) the dry rubber content (DRC) is at least 60% (see Table 1); iv) the non-rubber content (NRC) has a range of about 0.01 to 1.0%, preferably less than 0.5% (see Table 1); v) the pH is a basic pH, for example, the pH is in the range of about 8.0 to 12.0 (see Table 1); vi) the viscosity of about 60% TSC centipoises (cP) in an uncompounded form ranging from 35 to 100 cP; and a viscosity of about 60% TSC cP in a compounded form ranging from 40 to 200 cP; viii
  • the terms “parts per hundred rubber” or “PHR” is the measurement unit used to distribute various uncured rubber polymer, carbon black and non-black fillers, plasticizers, age resistors, vulcanizing ingredients, activators, and other special purpose ingredients.
  • spandex or “elastane” are used interchangeably, and both mean the same thing and are synthetic polyesterpolyurethane copolymer fibres that are known for their elasticity.
  • spandex include LYCRA, CREORA and INVIYA 1-300.
  • the term “spinning” to produce yarns including but not limited to: 1) “ring-spun” yarns, where the fibres are twisted around each other to give strength to the yarn; 2) “Rotor-spun” yarns, similar to ring-spun yarns, and made from short staple fibres that produce a more regular and smoother, though weaker, yarn than ring spinning; 3) “Twistless” yams where the fibres are held together by adhesives, not by the twist, and are often laid over a continuous filament core; and 4) “Wrap-spun” yarns where the staple fibres bound by another yarn, which is usually a continuous man-made filament yarn and can be made from either short or long staple fibres; 5) “Air-jet” spinning, a pneumatic method consisting of passing a drafted strand of fibers through one or two fluid nozzles located between the front roller of a drafting system and a take up a device.
  • the term “spinning” is also used in production of mono-filaments and fibres from natural fibers including but not limited to: 1) dryspinning whereby a polymer and a solvent is extruded through a spinneret into an evaporating chamber and hot air causes evaporation of the solvent and solidifies the filaments; 2) wet-spinning or liquid-spinning whereby polymer powder is dissolved in a solvent and extruded through spinneret into a coagulant to form fibers.; 3) electro- spinning substantially as described in Example 5; and 4) melt-spinning whereby rapid cooling systems are used to transform melted base materials into long strands or filaments.
  • the term “tensile strength” refers to how much force or stress, for example, a rubber material can withstand before breaking. The tensile strength of the rubber is expressed in the same units as modulus (Pascals) or pounds per square inch (psi). During this test, we pull the material up to the point of failure.
  • modulus Pascals
  • psi pounds per square inch
  • any of the methods described herein and in Figure 2 can be modified adapted to provide for the invention with a desirable tensile strength value.
  • the terms “tensile modulus” or “tensile stress” refers to tensile stress at a given elongation.
  • thermal stability or “thermal stable” to any thermal process performed to a fibre or fabric, for example in a steam atmosphere or a dry heat environment and remain its high performance (aka “heat setting”).
  • heat setting any of the methods described herein and in Figure 2 can be modified adapted to provide for the invention with a desirable thermal stability.
  • the term “thread” is a thin strand of yam used for sewing and a term associated with textiles and not natural rubber. Prior application uses of the term “thread” are replaced with “fiber” or “filament” or “fiber/filamenf ’ to describe the invention more accurately in the context of natural rubber and methods described herein.
  • the term “type 1 latex allergy” or “immediate- type” or “IgE-mediated latex allergy” or equivalents thereof refers to an immediate upon contact hypersensitivity to natural rubber latex and is an IgE-mediated, or immediate type hypersensitivity reaction to one or more proteins in natural rubber latex.
  • the purified natural rubber filaments are made from purified natural rubber latex and have not been shown to cause immediate hypersensitivity or IgE-mediated response in those with type 1 latex hypersensitivity.
  • the term “type IV latex allergy” or “cell- mediate latex allergy” or equivalents thereof refers to a cell-mediate contact dermatitis (type IV) reaction or skin inflammation upon contact or sensitivity to chemicals used to make latex products, rather than to rubber proteins themselves.
  • the term “UV stabile” or “UV stabilized” or its equivalent refers to a stabilizer(s) to a polymer or polymer resin to allow it to protect the substance from the long-term degradation from UV light. Any of the methods described herein and in Figures 1 and 4-12 can be modified adapted to provide for the invention with a desirable UV stability.
  • the term “yarn” refers to a linear and interlocked collection of filaments or fibres in a twisted state or bound by other means and possessing good tensile strength and elasticity properties. Fibres are processed in both pure and blended states, from both synthetic and natural materials. There are many different types of yarns including staple, continuous, novelty, industrial, high bulk and stretch yams. Yarns are further used in sewing, crocheting, knitting, weaving, embroidery, rope making, and the production of textiles.
  • the term “staple yams” refers to a yarn formed from staple fibres. These are small fibres that can be measured in cm or inches. Except for silk, all natural fibres (such as wool, flax and cotton) are staple fibres. Staple-fibre yams can be subdivided and classified on the basis of fibre length, spinning method and yarn construction and classified as either short staple or long staple with lengths of between 10 and 500 mm with short staple fibre having a maximum length of 60 mm (cotton fibre is a short staple at about 25-45 mm) and long staple fibres having a length of more than 60 mm (wool fibre is a long staple at about 60-150 mm).
  • continuous-filament yams are yarns that have high strength, uniformity and extruded e.g., through a spinneret.
  • the number of orifices in the spinneret dictates the number of filaments in the bundle; and the diameter and amount of drawing provided will subsequently decide the diameter of the filament.
  • novelty yarns refers to yarns that have decorative features and characteristics.
  • the term “industrial yams” refers to those yarns that are functional, designed and produced to satisfy a specific set of requirements.
  • the term “high-bulk yams” refers to yarns that can be a staple or continuous-filament yam with normal extensibility but an unusually high level of loftiness or fullness.
  • the term “stretch yarns” refers to yams that have high stretchability and cling without high pressure, good handle and covering power, e.g., Twist-heat set-untwist; Crimp heat-set; Stress under tension; Knit-deknit; Gear crimp.
  • vulcanization refers to a range of processes for hardening rubbers
  • vulcanized rubber refers to treatment of natural rubber with a vulcanizing agent, including but not limited to elemental sulfur, selenium, tellurium, sulfur compounds, peroxides, quinone compounds, amine compounds, resinous compounds, metal oxides and isocyanates.
  • vulcanizing agents include elemental sulfur and sulfur-containing compounds.
  • vulcanization and cure are used interchangeably.
  • Applicant is the first to describe the purification of natural rubber latex (and solid) and provide a commercial product that is substantially free of impurities and proteins (greater than 90%) while improving certain physical properties (e.g. tensile strength, elongation, modulus) and maintaining similar properties of unpurified or existing NRL (e.g. total solid or rubber content, pH, viscosity).
  • Applicant s publication WO2022/06393, Methods for making purified natural rubber and compositions, filed July 1, 2021 (PCT/US2021/040085) is hereby incorporated in its entirety by reference including the drawings.
  • One embodiment of the invention is to provide a purified natural rubber latex emulsion with greater than 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% and 99% of the total proteins removed.
  • There are standard test methods for determining the levels protein present including but not limited to FITkit® Hev b 6.02 that test certain latex allergens.
  • HPLC high-performance liquid chromatography
  • LC/MS liquid chromatography-mass spectrometry
  • ELISA enzyme-linked immuno-absorbent assay
  • ASTM D5712 is a Modified Lowry Standard method and is used to quantify the total extractable protein content of a test article or product.
  • the finest or smallest diameter natural rubber fiber that is commercially available is a 20 -110 count (about 11305 to 204 Denier) and is: i) talcum coated; ii) powderless; iii) silicone coated and combinations thereof.
  • Table 1 Product Specifications of Commercial Natural Rubber filaments
  • traditional extrusion methods are used for production of natural rubber or purified natural rubber filaments.
  • Compounded latex is added to a wet coacervated bath (e.g., 20 - 40 % acetic acid, thickness depending) and followed by washing with hot water, drying at 60 - 80°C in hot air and vulcanizing at 120 - 130°C in hot air and repeated until the filaments are properly cured.
  • the vulcanized filament is passed through a bed of talc and wound on to bobbins or drums and post cured at 60°C in hot air for 24 hr.
  • the coacervated batch the filaments are passed through a hot water bath where water-soluble impurities are leached out.
  • the filament is strong at this stage and is subjected to a ‘stretching’ process to control the final diameter.
  • the filament is then carried to a hot air chamber for drying and vulcanization.
  • the hot air chamber has a drying zone maintained at approx. 70°C and the vulcanization zone is at about 125 - 130°C. Between the two zones one more zone is maintained at intermediate temperatures between 70°C and 120°C.
  • the total time in the Vulcanizer depends on the diameter of the filament (typically between 5 to 7 minutes).
  • the filament is thoroughly dried before it reaches the vulcanization zone.
  • the filament is then passed through a bed of talc and is inspected for defects on an inspection table as part of the continuous process.
  • the filament is finally wound on bobbins or drums under slight tension.
  • the bobbins or drums are finally post cured at 60°C in hot air ovens for 24 hr. to complete the cure cycle.
  • Various other quality control tests are then carried out.
  • Figures 5 and 6 describe the Work Progression Flow of identifying, selecting and adapting methods for making natural rubber filaments as contemplated in the invention.
  • Rubber filament is currently being produced globally with primary density of suppliers located in Asia, and uses simple, low-cost equipment and production methods.
  • most manufacturers of rubber filaments source crude field rubber latex as the material of choice.
  • the reason for using field latex coincides with many of the other production strategies used by the industry, which revolve around costing pressures to provide large volumes of filament at the lowest price possible; and rubber filament is viewed as a commodity not a technology.
  • Advancements in the production (technology) also revolve around economics with a focus on producing more rubber and rubber filament therefrom for less, and many of the desirable physical properties that are seen as limiting factors in weaving have gone unattended.
  • FIG. 3 shows a method of extruded rubber filament (ERT) production is produced by extruding compounded latex through capillaries into a bath of coagulant, and the coagulated wet filament is then washed, dried, and vulcanized to produce an elastic filament.
  • ERT extruded rubber filament
  • the present invention describes specific examples, for example as depicted in Figures 5 & 6 for production of rubber filament using a natural rubber latex (FIG.5) or solid (FIG.6) source material with the physical properties as described in Example 2 and referred to herein.
  • the PENR particularly, the PENR latex (PENRL) can be further compounded (chemicals added) to improve its stability, to change and / or achieve additional or desired physical properties.
  • the viscosity of the NRL may be adjusted to a high level, and above that of typical latex used for dipping, to assist in formation of the rubber filament once injected into the coagulation bath and may increase in a range from 100 to 2,000 cP. See Figures 4 & 5.
  • rubber filaments can be extruded in a variety of fib er/fil ament diameters ranging from 0.10 mm to 1.5mm. Additionally the filaments may be formed as a round, flat, oval, or other cross-sectional shape. Other methods of rubber fiber/filament production include slicing very thin filaments from a solid flat sheet or ribbon of procured rubber. Various surface coatings are used to prevent sticking and can be talc, silicon, or clay. Some filaments are produced with an outer wrapping of synthetic fibre such as polyester, nylon or silicone, or naturally derived fibre such as cotton, wool, bamboo, or flax, etc. Natural rubber filaments are also described in Deniers.
  • breaking strain for example a 70-denier filament will be stronger than a 30-denier filament.
  • the natural rubber filaments described herein are not synthetic fibres, the size, thickness, or diameter of the natural rubber fibre uses regular metric units, e.g., millimeter, centimeters.
  • Still a correlation between the breaking strain for a natural rubber fiber/filament is analogous to that described above for synthetic fibres, i.e., the bigger the thickness or diameter of the natural rubber fiber/filament the stronger it is.
  • the PENR latex should be free from non-rubber constituents.
  • the compounding formulation should have minimum number of additives in solid form. Dispersions of compounding ingredients should be very finely ground during ball milling. Dispersions should be free from air bubbles / frothing. Air entrapment should be zero or minimum during various compounding and processing operations. Before extrusion, the compound should be passed through a very fine mesh and then allowed to be degassed by application of partial vacuum. Removal of excess shipping ammonia is to be accomplished by stirring latex compound on a warming plate below a ventilated extraction system. Always use proper and effective personal protection equipment and adhere to all safety precautions and standards. Disposal of waste latex may be accomplished by freezing the material to a solid and disposing of per country/state regulations only.
  • Drying and curing the PENR fiber/filament in hot air may be combined as described above and varying the temperature and rate according to the physical properties desired and/or until the fiber/filament is properly cured.
  • the extruded fiber/filament, which is wet is dried at about 84°C at about a rate of 35 meters per minute.
  • the dried fiber/filament is cured at less than 120°C, e.g., 112°C to 115°C at about 60 meters per minute and this cycle is repeated, 2x, 3x, 4x, 5x, 6x and so on until the fiber/filament is properly cured.
  • the latex is contained in a stirred and jacketed mixing vessel and the compounding ingredients such as those described in the Table above are added.
  • a mixing vessel with a heated jacket is used and hot water is passed through the jacket to heat the vessel.
  • the duration of heating will depend on the desired degree of cross linking has been achieved, which can be determined by various quality control testing now available or later invented (e.g., solvent swelling, combined Sulphur analysis or by assessment of tensile properties), but for about 3 - 5 hr. at about 50 - 60°C.
  • the latex compound is then cooled to room temperature and filtered or clarified centrifugally before use.
  • Prevulcanized latex is effective in small to medium sector dipped goods industries since further compounding of latex is not necessary or is limited to incorporation of desired pigments (e.g., manufacture of toy -balloons, medical goods, feeding bottle teats, etc.).
  • the cross linking can be achieved by reaction with Sulphur, Sulphur donors (e.g., TMTD, DTDM, TETD) or by gamma radiation.
  • Sulphur Sulphur donors
  • TMTD Sulphur donors
  • TMTD TMTD
  • DTDM DTDM
  • TETD gamma radiation
  • the compounding formulations can vary depending on end applications. If ZDEC / ZDBC is present, ZnO is not necessary. (ZnO reduces the film clarity and may be substituted by ZnCCh to improve the same).
  • prevulcanized latex reduces die swell by about 74- 80% on extrusion processes, providing smaller diameter and lower denier filaments. Prevulcanized latex also improves cure time and crosslink density.
  • prevulcanized latex can be blended with non-prevulcanized latex at 10:90, 20:80, 30:70, 40:60, 50:50, 60:40, 70:30, 80:20, 90: 10 and so on. Each blend will offer slight changes to physical properties.
  • a pre-vulcanized compounded natural rubber latex that is 50% prevulcanized reduces die swell by 50% and so on.
  • the preferred prevulcanization is greater than 40%, greater than 50%, greater than 60%, greater than 70%, greater than 80%, greater than 90%, about 100% depending again on the physical property desired and the application.
  • the sulfur to accelerator ratio during the pre-vulcanization process or even postvulcanization process has an impact on the crosslink density, hence modifications of the ratio of sulfur to accelerators may be necessary.
  • Some exemplars include but are not limited to: (i) high sulfur at about 2.0PHR to 6.0PHR and low accelerator at about 0.2PHR to 0.50PHR; (ii) sulfur at about 1.50PHR to 3.0PHR and accelerators at about 1 0PHR to 2.75PHR; and (iii) sulfur is low at about 1.0PHR to 0.50PHR and accelerators are high at about 1.25PHR to 4.0PHR; or multiple combinations thereof with a shift towards lowering or increasing sulfur to accelerator ratio.
  • Crosslink density alters as this ratio alters creating polysulfidic, disulfidic and mono sulfidic links.
  • Antioxidants act as protective agents in latex compounds depending on the nature of the product and the applications including but not limited to how and the conditions for use of the product, storage of the product, desired durability or longevity of the product, rigidness or stretchability and other desired properties for the product’s intended use.
  • natural rubber latex vulcanizates compounded (mixtures) using about 1.0 PHR of Zn-dialkyl dithiocarbamate accelerators may not need further antioxidant protection unless the products are very thin or the use of the product is beyond normal practical use.
  • Antioxidants and anti-ozonants used in the invention include but are not limited to Wingstay L, BHT, Durazone 37, Rickek 4729, EPDM, liquid, TBPA 70, Naugard 445 and typically is not greater than 1.5%, is not greater than 1.75% or is not greater than 2.0 PHR in total.
  • Wingstay L Wingstay L
  • BHT Durazone 37
  • Rickek 4729 EPDM
  • liquid TBPA 70
  • Naugard 445 typically is not greater than 1.5%, is not greater than 1.75% or is not greater than 2.0 PHR in total.
  • Ozone waxes which migrate and bloom to the surface to protect from ozone forms. Some wax types may even improve surface lubricity by providing a protective coating.
  • two or more protectants are used to form a synergistic value and fuller protection.
  • the following chemical types may prove to provide both antioxidant and antiozonant properties. See protective packages below.
  • amine derivatives such as 2, 2, 4-trimethyl-l, 2-dihydroquinoline (oligomers) (or TMQ) and N-Phenyl- 2-naphthyl amine (or PBNA) are more powerful antioxidants against the effect of heat, light, and trace metals but these tend to cause discoloration as the produce ages.
  • TMQ can be used for dark / black colored products where discoloration is not as noticeable.
  • phenolic antioxidants are weaker against degradative forces but do not cause any discoloration and are commonly used in all latex compounds.
  • the type and dosages of various phenolic antioxidants used for latex compounding may vary depending upon the end rubber product/application.
  • monophenols including but not limited to Butylated hydroxytoluene (or BHT), Styrenated Phenol, alkylated hindered phenols, and Bisphenols including but not limited to 2,2’-Methylenebis(6-tert-butyl-4- methylphenol) analytical standard (CAS No.: 119-47-1) (or A/O 2246), Polybutylated bis phenols, and thio bis phenols.
  • BHT Butylated hydroxytoluene
  • Styrenated Phenol Styrenated Phenol
  • alkylated hindered phenols alkylated hindered phenols
  • Bisphenols including but not limited to 2,2’-Methylenebis(6-tert-butyl-4- methylphenol) analytical standard (CAS No.: 119-47-1) (or A/O 2246), Polybutylated bis phenols, and thio bis phenols.
  • Wingstay L a butylated reaction product of p-cresol and dicyclopentadiene
  • Irganox 1010 - Tetrakis methylene 3-(3,5-dibutyl-4 hydroxyphenyl) propionate
  • Latex foam products such as carpet backings require antioxidants at 1.0 - 1.5 PHR amounts because the product demands longer service life or longevity (10 - 15 years), retention of cushioning effect to ensure long life for fibres, non-staining or slight discoloring characteristics, resistance to dyes (metal ions) and detergents (strong oxidizing agents), resistant to UV light and heat (longer drying conditions at high temperatures etc.).
  • latex dipped goods such as balloons, condoms, catheters etc. are thin-walled articles and hence need adequate protection.
  • Latex filaments as described herein require highly non-staining and persistent antioxidants along with resistance to detergents and the recommended antioxidant amounts (phr) will depend again on the application and field of use.
  • a few non-limiting examples include rubber fiber/filaments at about 0.5 - 1.0 phr Polyphenol and/or about 1.0 phr Styrenated phenol.
  • the lifetime and effectiveness of the antioxidants can be enhanced by the addition of a UV absorber such as benzothiazole derivative (Tinuvin P) or hydroxybenzophenones, which are colorless.
  • a UV absorber such as benzothiazole derivative (Tinuvin P) or hydroxybenzophenones, which are colorless.
  • Na-EDTA salt acts as a metal ion-chelating agent for copper and manganese ions.
  • the embodiments of the invention include that the natural rubber source material retains and maintains their optimal stability throughout the rubber fib er/fil ament production process. Poor practices during addition of materials or compounding can result in destabilization and/or poor homogeneity, which may cause downstream difficulties with processing or undesirable characteristics in the finished product.
  • the emulsion should be agitated gently with a mixer before and during addition of any ingredients. Agitation should be sufficient to produce good turnover at sufficient shear, or low shear, and without introducing excessive or large air bubbles, for example, such as that introduced when suspensions are vortexed.
  • Maintain the amount or volume of compounding may be forty to fifty (40- 50) gallons as when trials are being performed up to several thousand (1,000+) gallons for a production run. No limits to the amount or volume of compounded latex are suggested as it depends on the equipment capacity, manufacturing capacity and need.
  • NR or NRL that is heat labile or can withstand high temperatures while still maintaining its high-performance physical properties as described for PENR herein and in Example 2.
  • Super heat resistant fiber/filaments made from PENR should retain at least 80% of the modulus after exposure to dry heat of 150C for about 2 hours while non-PENR fiber/filaments would be expected to retain only about 50% modulus.
  • the latex should be heated to a specific temperature to stabilize and activate ingredients necessary to produce fiber/filaments of desired physical performance and visual appearance.
  • the storage temperature may range from 20C to 125C.
  • the compounded latex may be controlled at a lower temperature ranging between 5C and 15C.
  • the compounded latex may be warmed to production temperature prior to transfer and production as noted above.
  • Addition of any chemical agents or materials should have a pH as close to the emulsion as possible. All agents or materials should be added slowly to avoid again introducing air bubbles and reduce the risk of “shocking” the emulsion, which can induce local to widespread coagulation.
  • Filter NRL prior to use to remove any large particulates or coagulum that may have built up during mixing. This will help ensure a material of good consistency and help to reduce potential defects on subsequent, downstream, parts.
  • an easy means of filtering the NRL or PENRL compound is filtering it through 2-4 layers of cheesecloth or similar compatible materials (nylon, PE, PP) of adequate mesh size is recommended.
  • Use of basket type filtration systems work well for bulk filtration.
  • the compounded suspension will experience gradual changes during what is referred to as the maturation period or pot-life, which includes the storage conditions.
  • the time the compounded emulsion is in storage as well as the storage conditions will impact this maturation and the final physical properties of the rubber product made there from, including rubber fiber/filament.
  • the different materials mixed to form the compound will have the opportunity to interact and equilibrate.
  • cross-linking will slowly but steadily take place, particularly with the use of modern ultra-accelerators.
  • Sulfur to accelerator ratio will depend on the application and physical property desired of the product, but about 0.75 to about 2.50 PHR. Altering the sulfur cure has an impact on the crosslink density by shifting the ratio of sulfur to accelerators.
  • Embodiments herein include those where the sulfur is high at 2.0PHR to 6.0PHR and accelerators being low at 0.2PHR to 0.50PHR; a semi efficient method, where the sulfur is mid-point at 1.50PHR to 3.0PHR and accelerators at 1.0PHR to 2.75PHR; the Sulfur is low but still efficient at l.OPHR to 0.50PHR and accelerators at 1.25PHR to 4.0PHR; or multiple combinations thereof with a shift towards lowering or increasing sulfur to accelerator ratio.
  • Crosslink density alters as this ratio alters creating polysulfidic, disulfidic and mono sulfidic links.
  • Inorganic fillers are added to reduce cost and increase stiffness of the fib er/fil ament while influencing flow behavior of the compound.
  • the typical reinforcement effects of fillers as observed in dry rubber compounds are not observed in latex compounds.
  • carbon blacks or fine particle size clays do not enhance the tensile strength or tear strength since there is no mastication step involved in latex compounds and thus no free radicals are needed to interact with reactive sites on the fillers.
  • Clays soft and/or hard of fine particle size are used in the form of dispersion in water. It is necessary to check the pH of aqueous clay slurries is 7.0 - 8.0. Any acidity may be corrected by addition of dilute KOH solution. Clay loadings from 30 - 100 phr produce soft vulcanizates with higher tension set.
  • Anatase can also be used. Usually, 5 phr is used on dry basis and incorporated as 50% or 30% dispersion slurry.
  • White pigments are used to impart whiteness and to provide white background for pastel shades.
  • Blanc fixe Ppt. Barium Sulphate
  • Blanc fixe Ppt. Barium Sulphate filler is used to get smooth and strong deposits of white color on the products. However, it causes loss of extensibility, elongation, and sedimentation.
  • Carbon black is sometimes used as a black pigment; however, other pigments are commercially available and widely used depending on the product and application.
  • Organic fillers like high styrene resins enhance the stiffness and strength of the deposits based on latex compounds. There is a progressive increase in the modulus values of latex compounds without much loss in elongation at break when high styrene resins are used. These resin lattices are available for blending with NR latex and the proportions used are in the range of 10 - 25 phr.
  • natural rubber fibres comprise of about 80% or more natural rubber (e.g. 80%, 81%, 82%, 83%, 84%, 85%, 86%, 90% or more) and natural rubbers filaments with less than 80% natural rubber content (e.g., 50%, 55%connect 60%, 65%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78% or less), which can be accomplished by the addition of fillers, e.g. white fillers such as Dixie Clay, kaolin clays and/or calcium carbonate or equivalents now known or later developed.
  • fillers e.g. white fillers such as Dixie Clay, kaolin clays and/or calcium carbonate or equivalents now known or later developed.
  • White fillers are mineral based elements that can be from a class of filler systems used extensively in the rubber compounding industry and include: kaolin, silica, titanium dioxide, calcium carbonate, zinc oxide and talcs and may be organic or inorganic depending on their carbon structure.
  • Both kaolin clay (AKA, Dixie Clay) and calcium carbonate are used in latex compounding to impart physical properties and/or to reduce the cost of the compound by “filling” the formula in and reducing the amount and therefore cost of using latex rubber alone.
  • White fillers of all types have a steep benefit to physical properties impact in that lower percentages have little effect on elongation, tensile strength, tear strength and modulus (stiffness) up to a point and then decline very rapidly. See FIG. 20.
  • white fillers will increase stiffness or modulus even at lower loading levels.
  • the interaction between white fillers and sulfur curing agent loading or parts by weight (PHR, or percentage) is just as impactful as the type and amount of filler.
  • PHR sulfur curing agent loading or parts by weight
  • Trials will need to be run to determine if the sulfur dispersion needs to be reduced as a function of physical properties.
  • certain white fillers will fall towards the base pH scale white others may fall towards the acid pH scale and will be noted on their respective TDS or MSDS, so it is very important during compounding to monitor pH and make the necessary adjustments with ammonia (KOH), water or other pH adjustment agent. Always add dispersions slowly to avoid compound shock.
  • KOH ammonia
  • Kaolinite mineral clay As the best white filler for the filament project to modify the percentage of natural rubber content in the formulas and hence finished product.
  • the brand name Dixie Clay (Akron Dispersions) is a high-quality kaolin clay dispersion and is both frequently used in latex formulations and distributed by Emersive in Malaysia (emersive.com) across Asia with distribution hubs in Vietnam and Thailand.
  • Kaolinite is a clay mineral, with the chemical composition A12Si2Os(OH)4. It is an important industrial mineral. It is a layered silicate mineral, with one tetrahedral sheet of silica linked through oxygen atoms to one octahedral sheet of alumina octahedra.
  • the Dixie Clay dispersion is produced by adding finely milled kaolin clay into an attrition mill where water and soaps are added to produce a slurry of 45-60% solids content and milled for 48 hours to finely reduce the clay particle size. After milling the mixture is filtered, pH adjusted, and an antimicrobial added for protection and storage. The mixture is packaged and shipped. Upon arrival at the facility of use, the material is thoroughly mixed and stirred to blend all material that may have settled at the bottom of the container. Once mixed, the material is measured out for use through a filter of appropriate mesh size to remove any large agglomerates and chunks.
  • Figure 18 describes the count range for the different end-uses of staplefibre yams from fine yarn count of 2-7.5 tex meant for hosiery, staple-fibre yarns have almost similar market areas, where fine to medium yam counts of 7.5-40 tex are used to make textiles for clothing and apparel.
  • Spun staple yarns hold a major position in the market for items such as shirts, blouses, denim, athleisure wear, sportswear, and countless apparel and home textiles.
  • Figure 19 is a drawing describing a ring (conventional) spinning, a process that spins the short, raw fibre into a continuous yarn using a series of machines developed for cotton and wool: opening, carding, drawing, combing, roving, and spinning.
  • Opening is the process of reducing compressed cotton fibres from a bale into smaller-fibre tufts. It removes the particles of dirt, dust, and other impurities by using spiked rollers.
  • Carding After blending and opening, loose fibres are transferred to a carding machine. Carding is performed by opposing sets of teeth or small wire hooks known as card clothing, which cover the machine parts and include a licker-in, a cylinder, revolving flats, and a doffer. The cylinder and the flats may rotate in the same or opposing directions but at different speeds to tease the fibre tufts into a thin, filmy web, which is then collected into a loose rope-like structure called a sliver, which is often coiled, and deposited in cans.
  • the drawing frame uses a series of rollers arranged in pairs and rotating at different speeds. The fibres will be well parallelized and mixed after going through this process.
  • Combing is the process used to remove short fibres and neps (knot or tangle) from sheets of cotton fibres (lap). A roller with fine-toothed elements fixed on a half-lap is used. The amount and length of the short fibres extracted will depend on the combing parameters selected. The fibres will be straightened and paralleled during this process.
  • Ring spinning The conversion of roving into yarn is called the spinning process. This is usually done in a roller drafting system that will have some means of fibre control, such as a double apron. Twist is imparted to the fibre strands to prevent slippage through the ring and traveler. The yam is then wound onto suitable bobbins known as ring cops for further processing.
  • Figure 20 are images of uncovered natural rubber filaments made by the spinning processes described herein including but not limited to ring-spinning.
  • Figure 21 describes a process of hollow spindle spinning method.
  • Hollow spindle spinning replaces the twist in a yarn by wrapping a filament binder around the materials used. This results in a fasciated yarn structure in which most of the core fibres/yams run parallel to one another along the axis of the strand, while the binder imparts the necessary cohesion.
  • yarns made using the hollow-spindle system are quite different in structure from those made by the conventional ring-spinning system. They are also likely to differ in details of appearance and behavior during processing.
  • Hollow-spindle yarns are used in knitted garments or fabrics, although plain yarns have found many other applications such as carpets and medical textiles.
  • Figure 21 shows four independent feeding devices, three for effect fibres and one for the core yarn.
  • the effect fibres are fed in the form of staple roving or slivers.
  • the fibres are then drafted using a roller drafting system like that used on ring frames.
  • the effect fibres are combined with the core yarns and then passed through the rotating hollow spindle.
  • a bobbin bearing the binder usually a filament yam, is mounted on the hollow spindle and rotates with it.
  • the binder yarn is pulled into the hollow spindle from the top.
  • the rotation of the hollow spindle wraps the binder around the staple strand and the core yarns.
  • the binder then holds the effect and core yarns in place.
  • FIGS. 22 and 23 are drawings combining the benefits of the ring and hollow-spindle systems in a single machine, as it was thought that a yam with twist had a more stable and reliable structure than one with a fasciated structure. Later, it was recognized that two hollow spindles could also be assembled in series and that this would offer a variety of yarns and a different range of benefits.
  • Figure 22 shows two hollow spindles arranged one above the other, which wrap the staple strand with two binders applied in opposing directions. This technique is used to produce specialeffect yarns that have a more stable structure, as the effect fibres are trapped by two binders instead of one.
  • Figure 23 is a drawing showing a combined system in which the hollow spindle and ring spindle are combined in a single machine.
  • the wrapped yam is provided with some true twist by the ring spindle placed immediately below the hollow spindle.
  • the conventional doubling system is also based on ring spinning.
  • the arrangement provides two or more yarns that can be fed independently at controlled speeds. These may include uniform, fluctuating or intermittent feeds as required, so permitting a simple means of producing spiral or marl-type yarns, although obviously requiring the feed material to be in yarn form.
  • FIG. 24 is drawing showing a typical rotor system that can be used to produce coarse to medium count short staple yarns; whereas the friction system is used to make coarser industrial yams and either can be used for making some fancy yarns.
  • Figure 24 shows a rotor system where the yarn twisting action is separated from the winding action and the package needs to rotate only at a low winding speed.
  • the process may be divided into the following steps: opening, transport, alignment, and overlapping and twist insertion.
  • Individual fibres are carried into the rotor on an air stream and laid in contact with the collecting surface so that a strand of fibres is assembled around the circumference. As the fibres are drawn off, twist is imparted by the rotor, to produce a yam.
  • Rotor spinning is most suitable for spinning short staplefibre yams. Modem, computerized, and automated rotor spinning machines can make slub yarns.
  • FIG 25 is a diagram showing an open-ended spinning method called friction system (a DREF-2 machine).
  • friction system a DREF-2 machine
  • two friction rollers are used to collect the opened-up fibres and to twist them into yam.
  • the fibres are fed in sliver form and are opened by the opening roller.
  • the opened fibres are then blown off the opening roller by an air current and transported to the nip area of two perforated friction drums.
  • the fibres are drawn onto the surfaces of the friction drums by air suction.
  • the two friction drums rotate in the same direction, and twist is imparted to the fibre strands because of the friction with the two drum surfaces.
  • the yarn is withdrawn in the direction parallel to the axis of the friction drums and is delivered to a package-forming unit.
  • a high twisting speed can be obtained even while using a low speed for the friction drums, because the friction drum diameter is much larger than that of the yam.
  • FIG. 26 describes another type of open-ended spinning called vortex spinning to make fasciated yarn technologies.
  • the Murata Vortex spinning (MVS) for example can spin carded cotton yarns at speeds significantly higher than any other system currently in existence.
  • the machine produces yarn at 400 m/min, which is almost 20 times that of ring-spinning frame production.
  • Figure 27 is a diagram showing yet another method of spinning yarns called air-jet spinning, which is a pneumatic method and is not an open-end spinning process.
  • the drafted fibre strands pass through one or two air nozzles located between the front drafting roller and the take-up system.
  • the roller drafting system drafts the input sliver into a ribbon-like parallel fibre strand.
  • High-pressure air is injected into the nozzles, causing swirling airstreams inside the nozzle. This results in the insertion of false twists into the drafted fibre strands.
  • the edge fibres wrap onto the surface of core strand and form the yarn.
  • Figure 28 shows yet another method for spinning yarns, specifically chenille type yarns that form two ends at each unit.
  • the effect yarns are wrapped around a gauge or former which is triangularly shaped at the top, narrowing towards the base to allow the effect yam coils to slide downwards onto the cutting knife.
  • the width at the bottom of the gauge determines the effect length, by maintaining the depth of the pile, or ‘beard,’ in the final yam.
  • the cutting knife is shown in Figure 8.31 as a straight knife edge, modem machines all use a circular cutting knife.
  • On each side of the cutting knife there are two ground yarns, which may be either single or twofold. One ground yarn is guided by the takeup roller while the other is guided by the companion roller.
  • the take-up roller is pressed against the profiled guide and inter-meshes with the companion roller, allowing the two ground yams to trap the pile created by the effect yarn in between them at right angles to the ground yarn axis.
  • the two ground yarns are twisted together, usually by a ring spindle at the lower part of the machine, to produce the final yarn. Chenille effects can also be manufactured by a flocking process in which a ground yarn coated with adhesive is flocked electrostatically with loose fibres.
  • Weaving is the interlacement of two sets of fiber/filaments: the warp fib er/fil aments that run vertically through the length of the fabric and weft fiber/filaments that run horizontally across the width of the cloth on a loom.
  • looms table loom, rigid heddle loom, floor/treadle loom, counterbalanced loom, dobby loom, computerized loom (e.g.
  • Frame Secures components
  • Beam Secures and stores the warp and is at the back of the loom. Some looms have more than one beam. If the loom has more than one back beam, it can be used for weaving two different types of warps for double cloth or warps at different tensions.
  • the cloth beam at the front stores finished weaving.
  • the width of each beam determines the extent of the width of the cloth.
  • Shafts Consist of an upper and lower bar carrying the heddles.
  • Heddles Rest on the shafts of the loom. The warp yarns are threaded through the eye of the heddles.
  • Batten Pivoted frame holding the reed. It can hang from the top of the loom (overslung) or be pivoted at floor level (underslung).
  • Reed Used for spacing the warp and beating the weft. It can vary in size and ideally it should be made of stainless steel to prevent rusting.
  • Levers (table loom) or peddles (floor loom): Raise and lower the shafts. Levers are placed at one or both sides of the frame. Peddles may be pivoted from the front or back.
  • Knitting is producing a textile fabric from a series of intermeshing loops.
  • Different methodologies exist most modem knitwear is produced using sophisticated computer-controlled machinery (weft knitting), which is derived from either hand or pin or needle knitting, which involves two large needles or pins and a single end of yarn.
  • Weft knitting is derived from either hand or pin or needle knitting, which involves two large needles or pins and a single end of yarn.
  • Knitted fabrics vary significantly in weight, from ultra-lightweight (termed fine gauge) used in sporting and underwear applications, to heavier structures used in outerwear sweaters (termed chunky gauge).
  • gauge refers to the fineness of the fabric, although it actually refers to the number of needles (per inch) within the needle bed (although there are notable exceptions: in some older weft-knitting machinery the gauge is expressed as number of needles per 1.5 inches, and in raschel warp knitting machines it is number of needles per 2 inches). But in general terms, 18-, 14-, 12- and 10-gauge machines produce lightweight fabrics; midweight fabrics are produced on 8 or 7 gauge; and 5, 3 and 2.5 gauges produce heavyweight fabrics. There are two distinct types of knitting technologies that produce vastly different fabrics for specific applications (weft and warp).
  • Most knitted garments available are constructed from weft-knitted fabrics. This is by far the most versatile method of knitting, as the technology allows for a variety of structures to be produced that can combine extensive patterning in the form of texture and color.
  • Weft-knitted fabrics are flexible and will extend in all directions, have good elastic recovery, superb formability, and drape, provide excellent thermal insulation and are resistant to creases. However, they suffer from poor shape retention, are prone to pilling and ladder easily.
  • warp knitted structures are more stable but lack drape properties. Warp knitted structures are produced using multiple yarn ends and the loops intermesh diagonally with the adjacent vertical columns. The resultant fabrics are ladder resistant and find end-uses in a variety of areas including, lace, openwork, net, underwear, sportswear, and technical applications.
  • weft-knitting machinery circular, fully fashioned and flatbed and that which produce seamless garments.
  • the most productive method of manufacturing weft-knitted fabrics is utilizing the circular knitting machine.
  • the knitting needles are arranged in a circular formation and can be fed from a variety of sources located around the circumference of the machine; hence more than one course is knitted in a single revolution.
  • the fabrics obtained from this machine are continuous tubes that can be slit to produce an open width fabric.
  • Single- and double-jersey fabrics utilized in T-shirts and sweatshirts are manufactured using this technology.
  • One example of recent advances in circular technology includes seamless Santoni technology. Santoni has produced small diameter machines that produce a tube of fabric to fit over the body contour.
  • the modern flatbed machines are the most versatile of all weft-knitting technology. They can produce ribs combined with complex structures, different patterning options, panel shaping and integral knitting (knitting pockets, collars, and trims into the garment). The only disadvantage is speed, but this has improved significantly in recent years (the latest technology operates at 1.6 m/s). Most fashion knitwear (excluding T-shirts) on the high street is produced using flatbed machinery. There are two major players in this area of innovation: the German company Stoll, with its Knit & Wear range of machinery, and the Japanese company Shima Seiki with its Whole garment machinery range. These machines are designed to produce a complete garment; hence, the entire sweater or other garment produced by one of these machines is seamless and there are no post knitting operations to be completed after knitting (except for labelling and sewing in the ends of yarn).
  • Warp knitted structures are constructed from intertwined loops, with the yarns that connect them crossing in a zigzag formation.
  • a warp knitting machine consists of needles extending across the width of the machine like a weft machine, but each individual needle is fed from an independent yarn source. Hence, each needle is fed by its own yarn supply delivered by a guide that directs the yarn around the needle during the knitting action. It should be noted that all the wales in one course (i.e., vertical column) are formed simultaneously. The yams that feed through the guide bars are wrapped onto a warp beam (like the weaving process); a machine could consist of two to four beams depending on the fabric type to be obtained.
  • Warp knitted fabrics produced are continuous sheets of materials and usually produced from filament yarns which can be utilized in a variety of applications from industrial to fashion garments.
  • the varieties of fabrics that can be produced are among the widest ranges of any textile manufacturing method.
  • machinery available in a variety of widths from small crochet and scarf making machines, to gigantic machinery (5 m wide) used to produce industrial fabrics. Whilst both warp and weft technologies are referred to as knitting, the fabrics produced are so vastly different.
  • Tricot and raschel warp are 2 types of knitting machines.
  • the structures obtained from the tricot machine are of the plain type and find many applications, particularly in lingerie and Sportswear; quite often, these incorporate elastane or Lycra to produce fabrics with two-way stretch.
  • Raschel machines can knit yams in both filament and staple form into open works, laces, jacquards, fancywork (largest outlet) and pile fabrics. Structures produced from the raschel machine do not tend to stretch significantly and can be designed to be highly structural for technical applications.
  • Shima Seiki s most recent machine range is the Mach 2X and Mach 2S, which claims significantly higher productivity than earlier versions of whole garment and is programmed through the SDS-ONE APEX design software.
  • Various models of Stoll’s CMS Knit & Wear machinery are available, and programmable using Ml Plus software.
  • the advantages of producing using complete garment technology are elimination of waste, reduced labor (compared to other methods) and comfort (due to having no seams) in close-to-body-fitting garments.
  • the most common warp knitted structures in clothing and Fashion are those produced using the tricot type of machine.
  • the most common warp knitted structures to be produced are those of the plain tricot type knitted with two needle bars.
  • nonwoven fabric is a sheet of fibres, continuous filaments or chopped yarns of any nature or origin, which have been formed into a web by any means, and bonded together by any means, except for weaving or knitting.
  • a nonwoven fabric structure is different from some other textile structures in the following aspects: i) It principally consists of individual fibres or layers of fibrous webs rather than yarns; ii) It is anisotropic both in terms of its structure and properties due to both fibre alignment (i.e. the fibre orientation distribution) and the arrangement of the bonding points in its structure.; iii) It is usually not completely uniform in fabric weight, fabric thickness or both; and iv) It is highly porous and permeable. Hence, it is possible that non-woven fabrics have yams made of PENR fibres all the same.
  • a holistic view of sustainability focuses not only on manufacturing and safety, but also on the end of the product life cycle and its impact. If it is not reused, recycled, upcycled, or repurposed in some way, textiles often end up in a landfill or compost. Biodegradable textile products should ideally degrade completely in the soil and residues or degradation products from dyeing or finishing processes should have no negative impact on the environment.
  • Biodegradation product testing when intended for product claims related to biodegradability, should incorporate several factors of the product’s actual performance, or intended use.
  • products can be tested for ‘Ready Biodegradability’ under OECD 301B biodegradation test method.
  • OECD 302B is an inherent aerobic biodegradation test used for determining the biodegradability of a solution typically not readily biodegradable, is known to be insoluble or does not satisfy the requirements of OECD 301.
  • Biodegradation testing for plastics is typically run in conditions approximating commercial composting; biodegradation tests for liquids are run in representative aquatic systems. For example, plastic disintegration is typically under ISO 16929 and OECD 30 IB for liquid biodegradation.
  • Biodegradability testing measures the complex biochemical process that occurs when microorganisms consume a given type of material. And although complicated, the test results measure simple markers of the biodegradation process. Some regulations require biodegradability claims to be based on aerobic biodegradation, which typically measures oxygen consumption, CO2 production and the state of inorganic carbon intermediates.
  • Typical properties of denim are cotton or cotton-polyester blend, durable light to heavy weight twill weave, and yarn-dyed fabric.
  • Other features include: i) colored warp and white weft; ii) left-hand twill with a blue (indigo) warp white weft; iii) warp-faced twill; iv) available in 203.46 gm/m2 (6 oz/yd2) to 474.74 gm/m2 (14 6 oz/yd2) or more in a 2/1 or 3/1 interlacing pattern; v) napped, printed, made with spandex or other stretch yarns, or modified for fashion.
  • the yarns for denim also have typical features including: i) minimum staple length: 2.7 cm; ii) proportion of short fibres (less than 12 mm long): iii) under 40%: Micronaire value: 4.0 to 4.5; iv) count range of denim warp yams is 50 to 90 tex and weft yams is 75 to 120 tex; finer yarns as fine as 25 tex in twill or plain weave are used in denim shirts.
  • Denim is measured by how many ounces are in a square yard of fabric. Usually lightweight denim is 5-12 ounces (oz), mid-weight is 12-16oz, over 16oz is considered heavyweight. Many manufacturers and consumers consider 13-16oz mid- heavy-weight denim. Designers and manufacturers will choose which denim is the most appropriate given the season and type of clothing being made. Lightweight fabric (denim or otherwise) is usually much more supple and flowy. It is often reserved for tops, some skirts, and summer clothing, whereas most jeans, shirts, and jackets are made with 1 l-13oz denim, which is enough heft (or bulk) to make it durable and still comfortable for most weather to make it very wearable. In contrast, heavy-weight denim (or other heavy bulky fabrics) is used for upholstery and occasionally for jeans and jackets. Thus, denim weight matters for comfort and performance, which dictates applications.
  • Denim weight is a combination of how thick the yam used to make the fabric is, how tightly woven the yarn is, and how much the yam weighs. If cotton is blended with polyester rather than elastane, there will be a weight differential, as well as having different stretch and durability characteristics. So, 1 loz blended denim will be different depending on what it is combined with. Even if the fabric is all cotton, different looms will weave fabric in different densities or yarn count (mass per unit length). Traditional selvedge jeans are often made on older shuttle looms, especially Japanese selvedge jeans. The denim from these looms is packed in tighter than completely automated bullet looms yet retain its flexibility and softer hand even though they may be of a higher weight.
  • Fabric weight may also dictate the style, especially of jeans. Very heavyweight denim requires a baggier fit because skinny jeans with the same fabric will create skin abrasion and fabric-on-fabric abrasion. Lightweight denim is suitable for skinny jeans, very high-waisted or very wide-legged fashion jeans, where movement is required or necessary.
  • Publication W02020084359 (Candiani) describes elastic yarns and fabrics made from the elasticized yarns, in particular stretch denim.
  • Commercial availability of natural rubber fibers at the time did not allow for a denim of 13 oz or 12 oz or 11 oz or less, which is more desirable; and may be the reason why Candiani required 3 drafts, which is a process of attenuating or stretching the fibers as a way to manipulate the roving (1) during the spinning process as shown in FIG.l of W02020084359.
  • Spandex or elastane is a synthetic fibre known for its exceptional elasticity. It is a polyether-polyurea copolymer that was invented in 1958 by chemist Joseph Shivers at DuPont's Benger Laboratory in Waynesboro, Virginia. When introduced in 1962, it revolutionized many areas of the clothing industry.
  • the name “spandex” is an anagram of the word “expands”. It is the preferred name in North America; in continental Europe it is referred to by variants of "elastane", i.e.
  • elasthanne France
  • Elastan Germany, Sweden
  • elastano Spain
  • elastam Italy
  • elastaan Netherlands
  • Brand names for spandex include Lycra (made by Koch subsidiary Invista, previously a part of DuPont), Elaspan (also Invista), Acepora (Taekwang), Creora (Hyosung), INVIYA (Indorama Corporation), ROICA and Dorlastan (Asahi Kasei), Linel (Fillattice), and ESPA (Toyobo).
  • Spandex fibres are produced in four different ways: (i) melt extrusion; (ii) reaction spinning; (iii) solution dry spinning, and (iv) solution wet spinning. All these methods include the initial step of reacting monomers to produce a prepolymer. Once the prepolymer is formed, it is reacted further in various ways and drawn out to make the fibres.
  • the solution dry spinning method is used to produce over 94.5% of the world's spandex fibres, and the process has five steps: (1) Produce the prepolymer by mixing a macroglycol with a diisocyanate monomer (1 :2 ratio) in a reaction vessel to produce a prepolymer; (2) React an equal amount of diamine and known as polymer chain extension and then diluted with a solvent (e.g., DMAc) to produce the spinning solution. The solvent helps make the solution thinner and easier to handle, and then it can be pumped into the fibre production cell; (3) The resulting or spinning solution is pumped into a cylindrical spinning cell where it is cured and forced through a metal plate called a spinneret and converted into fibres.
  • a solvent e.g., DMAc
  • spandex Because of its elasticity and strength, (stretching up to five times its length), spandex has been incorporated into a wide range of garments, especially in skin-tight garments. A benefit of spandex is its significant strength and elasticity and its ability to return to the original shape after stretching and faster drying than ordinary fabrics.
  • spandex and its family of elastic fibres are still commercially made from synthetic polymers and are not bio-based.
  • synthetic polymers are not bio-based.
  • Figures 5 and 6 are general process flow diagram and decision tree, respectively, for use in the present invention.
  • the results below for the high- performance natural rubber fibre show that it can be: i) stretched repeatedly and still recover to very near its original length and shape; ii) stretched more than 500% without breaking; iii) having substantially the same retractive force as elastane or spandex; iv) heat-settable; v) dyeable; vi) resistant to deterioration by body oils, perspiration, lotions or detergents; vii) Abrasion resistant; viii) lightweight, soft, smooth, supple; ix) prevents bagging and sagging when incorporated into fabrics and textiles.
  • Tables 1-7 describe the test results from the purified NR using methods described herein (FIG.2). Legend for analyzing these Tables and Figures: Pure NR (purified NR of the present disclosure), Crude (crude Hevea NRL), Centrifuge (crude Hevea NRL centrifuge or concentrated), LP (Hevea Low Protein from Vytex), LP-1 and LP-2 (different lots of Hevea Low Protein from Vytex).
  • TSC Total Solids Content
  • NRC Total percentage of Non-Rubber Content
  • TRC Total Rubber Content
  • Received total protein ranged from a max of 12.465 ug/g to a min of 4,432 ug/g and an average of 7,107ug/g. After each lot was purified per the methods described herein, they averaged 138 ug/g with a low of non-detect ( ⁇ 50 ug/g) to a high of 400 ug/g.
  • the range correlates to a range of dilution wash ratios tested which ranged from 1 : 1 to 17: 1 where the dilution increased to a point that dropped TSC to below 8%. The higher the dilution ratio the greater the total amount of protein removed up to 9/10: 1 where no measurable detection was possible, process periods increased, and total production system loss elevated. See also FIG.9 and Table 1-3.
  • Dried Latex Color air-dried, not coagulated. This tests for the clarity and color of the NRL after purification methods as described herein. Visual comparison was made from 1.5mm to 2.5mm thick cast and air-dried NRL. See FIG. 4A comparing purified, crude, and low protein NRL that were transparent, off-white & yellow, respectively. Visual comparison demonstrated a significant decrease in typical yellow-ish color. All ten (10) lots crude Hevea NRL purchased and purified as described herein showed near transparent clarity over crude Hevea and more significantly of the Hevea Low Protein NRL lots/samples. See also FIG.4.
  • Dried Latex Color (coagulated). This tests the color of the coagulated NRL. There was a markedly different coloring between the purified NRL of the present disclosure as compared to both the rib smoked sheet (RSS) solid NR and the baled oven dried NR. See also FIG.4B.
  • Uncompounded Green Strength Tensile. This tests the overall general physical properties after purification methods as described herein as compared to crude NRL. Four (4) different types of commercially available NRL were tested. All the NRL (purified, crude and Low Protein) was put in a cast film and compared against two (2) commercially available centrifuged high ammonia and a low ammonia NRL, and two (2) different lots of Low Protein NRL. Each type was cast with three 1.5mm films, which were air dried after one (1) hour at 60C._Green strength improved after purification of the NRL as described herein and averaged 8.1 from a low of 3.2 Mpa. The feedstock used to produce the purified NRL was baseline and found to produce 3.1 Mpa. See Tables 1- 3.
  • the pH of the NRL is a general indicator of bacterial activity. That is, as pH drops there is greater potential for growth of bacteria and mold/yeast. This growth appears flat for several days and then there was a rapid decrease in pH as growth increase logarithmically. Purity of the latex reduces these pH-changing loads and allows for a longer maintenance of pH without the need for additional ammonia, bactericide, or KOH.
  • Compounded Strength Tensile, Elongation & Modulus.
  • Compounded Strength Pot Life. This tests the shelf life of the compounded NR before it is used in manufacturing of the rubber product. Pot Life across the purified NRL lots averaged 4.65 weeks as compared to an average of 2.98 weeks for non-purified NRL lots/samples, which decreased at about 12% and then rapidly decreased to 31.6% by mid-week three.
  • Uncompounded Mechanical Stability Test This tests the stability of the latex prior to compounding. Steady state for MST testing compared to crude Hevea NRL samples held for a five (5) week period.
  • %BW Coagulum Percentage
  • Natural rubber latexes were used for testing as described in the Tests section above and described in the Results section herein. Certain NRL samples were taken prior to processing the latex as in purification described herein as well as during the purification process and after. All samples were compounded using a typical dipped article, which was then used for physical testing. Both compounded and uncompounded latexes were evaluated in a similar manner. Tables 3 & 4 are a summary of certain of the tests and samples described herein. [00263] The compound formula used to test the samples consists of 100 NRL emulsion (purified, crude, or low protein), 0.1 Calsoft L-40, 5 Bostex 827, and 1.0 Wingstay L.
  • This compound is a basic compound that utilizes a master batch cure package available from Akron Dispersions (Bostex 827), which is a typical NR cure package for Hevea. This provides acceptable and comparable properties. Twelve dipped sample articles were produced from each compounded batch and tested in the laboratory for tensile, elongation and modulus properties. The data in Table 3 below is an average across all twelve samples produced and tested including those samples with incorporated impurities. The baseline purified NRL was compounded and then separated into four, 1 L samples where different percentages of the impurities were added back in as described above under the testing (1.5%, 1.75%, 2.75%).
  • a dipped article was produced from each on day one, then after three days of pot maturation, and then a series of four test articles were produced from each test sample, cured, dried, and tested for their respective physical properties, the results of which are described in more detail below. Additionally, uncompounded cast films were produced to test green strength.
  • S3-X1, X2 are purified NR produced from methods as described herein but are compound formulas to enhance end-product performance properties in certain areas and do not necessarily demonstrate total optimization of the methods disclosed herein.
  • Table 8 Green Strength & Color of Purified Compared to Unpurified Natural
  • S3-X1, X2 are purified NR produced from methods as described herein but are compound formulas to enhance end-product performance properties in certain areas and do not necessarily demonstrate total optimization of the methods disclosed herein.
  • Methods for production of an improved natural rubber fiber/filament relies principally on several factors: (i) High performance source material or NRL with superior physical properties, specifically the PNR or PENRL source material as described in Example 2 and as defined in the application herein; (ii) Scalable process and ready on demand; (iii) Standard equipment to allow for quick adaption and entry into the field as compared to customized standards; (iv) Standard equipment that is easy and economical to modify and/or customize; (v) Common chemical methods and agents for easy adaption or adoption, and with standardized equipment or slightly modified equipment; (vi) Chemistries that do not require organic, inorganic or volatile organic compound (VOC) emitter type of solvents; (vii) Chemistries that do not require catalysts (catalyst free); and (viii) Chemistries capable of allowing the natural rubber fiber/filament to be dyed and color matched to the desired fabric.
  • VOC organic, inorganic or volatile organic compound
  • Figure 7 describes a general process for production of rubber fib er/fil ament from latex or NRL source material
  • Figure 8 describes a process for making natural rubber fiber/filament from PENRL source material
  • Figure 8 describes a general process for production of rubber fiber/filament from solid rubber source material
  • Figures 10 & 12 describe a process for making natural rubber fiber/filament from solid rubber derived from PENRL source material.
  • this method can be utilized for making rubber fiber/filament from any natural rubber latex source, it is hereby described a method for making rubber fiber/filament from PENRL (1) as described above in Example 2 and also referred herein as “elastomeric source material (1)” or “PENRL source material (1)” or equivalents thereof, is a natural rubber latex that has been compounded to obtain certain physical properties or characteristics of a purified or premium NRL including but is not limited to the following physical properties: 1) the total range of protein content is about 50 ug/g to about 200ug/g; 2- the total solids content (TSC) range is between about 35% to 70%, depending on the process parameters and the desired TSC level for the process or requirements for a machine or industry or field; 3- the dry rubber content (DRC) has a range from about 35% to 70%; 4- the non-rubber content (NRC) has a range of about 0.01 to 1.0%; 5- the pH is a basic pH, for example, the pH is in the range of about 8.0 to
  • the NRL or PENRL source material may be further compounded depending on the purity of the source material and the physical properties desired in the product made from the NRL / PENRL (“latex”).
  • the final latex emulsion compound (4) can be transferred under pressure (4a) to the extrusion unit (5).
  • the transfer (4a) may be accomplished by means of a Sine type Pump unit to ensure proper handling is achieved and limit friction coagulation formation inside the pump, pump head, connecting tubing and pipes, as well as the extruder unit (5) itself.
  • the transfer (4a) may incorporate any number of removable filters (more than one) to further separate the latex according or e.g., pore size. Filter or filters in the transfer unit (4a) may e.g., also capture unwanted coagulant or other foreign material particles from the latex (4) and further clean and purify the source material.
  • the extruder (5) supplies necessary forming head pressure from an internal pumping supply system, so the transfer (4a) pump is required to supply the required volume of PENRL to ensure the extruder (5) does not run low on PENRL in its internal reservoir tank.
  • the transfer (4a) pump shall supply a volume range from about 0.5 LPM (Liters per Minute) to about 50 LPM.
  • a plurality of pumps may be utilized to adequately flow the desired volume of PENRL.
  • the filter(s) may have about a 600-400-micron size (medium) range.
  • the extruder (5) may contain additional internal filter(s) prior to discharge at the forming extruder injection head (5a).
  • the transfer system may contain multiple filtration units in series with larger pore mediums first in series order to a final smaller pore medium prior to entering the extruder injection vessel and discharge pump unit.
  • the PENRL extruder unit (5) ordinarily consists of a reservoir to hold an amount of compounded latex at an appropriate temperature, filter assemblies, internal high-pressure pump, connecting pipe and hoses which transfer the PENRL from the reservoir to the extrusion head (5a).
  • the extrusion head (5a) may consist of one or more small orifice that communicates directly or indirectly with a liquid coagulation bath (6) whereby the extruded and injected latex material is forced under pressure through the orifice located in the extruder head (5a) forming a thin diameter range from about 0.8mm to about 10.0mm length of latex, while instantaneously (rapidly) the exposed latex contacts the coagulation liquid set bath (6) and becomes semi solid or firm. As more latex is exposed to the coagulation liquid set bath (6) the length of the now solidifying thread increases continuously.
  • the coagulation liquid which is low in pH (ranging from about 1.0 to about 6.0 pH) reacts to the latex causing the micro particles to adhere to each other forming a semi solid.
  • the extruder forming head (5a) may contain a multiplicity of forming orifices (openings) capable of producing more than one (1) fiber/filament and up to 1,000 fiber/filaments or more depending on configuration of the equipment. See Figure 8 for diagrams showing a cross-section of a single (A) or multiple (B) fiber/filament configurations.
  • the extruder forming head (5a) consists of an exit orifice in a singular configuration. Additionally, the forming head (5a) may be designed with a multiplicity of orifices which produce multiple fiber/filament segments at once.
  • Figure 14 illustrates some non-limiting examples of cross-section configurations of rubber fiber/filaments.
  • Figure 13 illustrates one embodiment of the dimensions of the fiber/filament diameter as a function of the orifice diameter size (single and plurality).
  • the diameter size is determined by the pressure or force of the latex exiting the forming head orifice (FIG.13, single or multiple), the viscosity of the latex, rheology of the latex and may be altered by manipulating the flow characteristics of the latex.
  • the solidifying rubber fiber/filament will become firmer from the outside inward for a period until the entire fiber/filament length solidifies fully. Once fully solidified the rubber fiber/filament may be handled and taken out of the coagulation liquid set bath (6) without tearing apart.
  • the extruder (5) may be fitted with a single fiber/filament forming head, multiple fiber/filaments forming head (FIG.13) as well as multiple heads to produce a multiplicity of fiber/filament lengths simultaneously. There may be an equipment configuration whereby multiple extruders are arranged and communicate to the coagulation liquid bath (6).
  • the coagulation set bath (6) contains the coagulation liquid which is a pH- controlled liquid that consists of water (H2O) being most of the bath volume. Chemicals are added to the water to reduce the pH level below about 8.0 pH.
  • the pH of the coagulation liquid may range from about 1.0 to about 8.0 pH and can be adjusted to suit specific fiber/filament production characteristics and parameters. For example, an acid is added to the coagulation water to reduce and control the pH level between about 3.0 to about 6.5, more preferably about 3.5 to about 5.5.
  • Such acids include but are not limited to: Acetic Acid, Sulfuric Acid, Methanoic Acid, Formic Acid, Carbonic Acid, Phosphoric Acid, and/or Hydrochloric Acid [00279] It is also provided that a mixture of two (2) or more selected acids may be utilized to create a coagulation bath liquid suitable to form an exterior solidified skin on the fib er/fil ament length instantaneous to contacting the coagulation liquid by the compounded latex.
  • the coagulation set bath (6) may additionally have a system to warm the bath liquid and maintain it at a specific temperature for the duration of the production cycle, or change it gradual (e.g., cooling) for a different purpose or a rubber fib er/fil ament with different physical properties.
  • the bath may utilize an electric heating element affixed to the exterior of the bath walls, steam heat or other suitable methods and accessories to heat up liquids.
  • the bath temperature is maintained at a temperature between its lower and upper set points whereby the range may be from about 20C (68F) to about 100C (212F), preferably between about 48C (120F) and about 72C (165F).
  • a series of thermal probe sensors may be utilized to measure multiple areas of the bath and provide an average temperature. This measurement may be communicated to a control unit, which in turn can control the heating elements to increase or decrease the temperature.
  • a suggested control resolution of the set point may be +/- 10%.
  • the extruder forming head (5a) in this configuration is submerged under the coagulation set bath (6) level allowing the ejected latex compound to instantly contact the coagulation liquid.
  • the ejected fiber/filament lengths are continuously exposed to the coagulation liquid upon exiting the forming head.
  • the fiber/filaments are pulled and managed through the length of the coagulation set bath (6), out of the coagulation set (6) bath and onto the fiber/filament separation and training table platform (7), which may be located inside the flash oven and through the entirety of the production system.
  • the fiber/filament separation and training table (7) is located at the exit of the coagulation set bath and provided to effectively train or run the fiber/filament upon exiting the coagulation bath(6).
  • the fiber/filament is washed with fresh water of a neutral pH prior to entering the flash oven (8).
  • the wash water pH range is between 6.5 to 7.8 pH with a preferable set point being 7.0 pH.
  • the fiber/filament lengths are stretched by rollers (9) operating at synchronous speeds and in some embodiments at differential speeds which cause the fib er/fil ament to be pulled longitudinally which while in the uncured state cause the fib er/fil ament’ s diameter to reduce.
  • the fiber/filament length enters a forming ring to reduce its diameter and may repeat this forming ring step multiple times to form the desired fiber/filament cross section. See Figure 9 for nonlimiting examples of various cross-sections of fiber/filament diameters.
  • the flash cure oven (8) is located at the exit of the separation and training table platform (7).
  • the oven (8) may in this configuration house the separation and training table platform (7).
  • the flash cure oven (8) is utilized to quickly set the fiber/filament firmness to ensure proper handling of the fiber/filament across the production system and ahead of the final cure oven (10).
  • the flash cure oven (8, 10) may be heated using electrical heating elements, UV lights, infrared lights and microwaves or a combination thereof two or more energy supplying methods.
  • the flash cure oven (8, 10) can provide the necessary temperature within the unit in a range from 40C (104F) to 150C (300F) and is able to maintain a temperature set point more preferably of 100C (212F) and hold a resolution of +-10%. In some embodiments the oven is not utilized due to the strength of the fiber/filament exiting the coagulation bath and is dependent upon the latex compound formulation and time spent in the coagulation bath.
  • rollers (9) are provided as a method of further forming the fiber/filament’ s cross-sectional shape.
  • the fiber/filament material may be deformed in such a manner as to set a cross-sectional shape.
  • a single roller or a multiplicity of rollers may be established in this configuration.
  • a curing oven (8, 10) is provided to fully cure, set, and vulcanize the fiber/filament in a finished condition.
  • the oven may be heated using electrical heating elements, UV lights, infrared lights and microwaves or a combination thereof two or more energy supplying methods depending on the cure chemical system selected during compounding.
  • the curing oven may have a temperature range from 120C (248F) to 150C (300F) preferably with a set point of 130C (266F).
  • the fiber/filament will reside (dwell) in the oven (10) for a period of time necessary to fully cure the fiber/filament latex compound and may range from 5min to 20min with a more preferably set point period of lOmin depending on thickness of fiber/filament, curing agent used and performance characteristics of the fiber/filament required.
  • the curing oven (10) is configured to have a multiplicity of rollers whereby the fiber/filament length is wrap around such a roller to increase the total length of the fiber/filament in the oven at one time and operates at such a speed to coincide with the time period of the cure.
  • the cure oven (10) may contain several linear feet of fiber/filament or in some embodiments and design configurations may contain several hundred (100) linear feet of fiber/filament.
  • the speed of the fiber/filament moving through the oven may be in millimeters per minute to millimeters per hour and range from ten millimeters per hour to ten millimeters per minute or faster depending on the desired cure condition of the fiber/filament.
  • the curing oven may utilize forced flow of air to enhance curing of the fiber/filament.
  • Methods are also provided for coating the rubber fiber/filament in a fiber/filament coating bath(s) (11) to prevent the fiber/filaments from sticking together when wound on the finish uptake spool (17).
  • Additional fiber/filament coating bath(s) (11) may also serve the purpose of providing a required finish rubber fiber/filament, for example, one that offers low friction or other characteristics.
  • a variety of coatings, both wet and dry, are suggested including but are not limited to talc (dry), silicone (wet), paraffin wax (wet), polymer (wet) and/or natural material e.g., cotton, or any combination of these.
  • the coated fiber/filament may exit a bath, be dried, and reenter a secondary coating bath prior to exiting and drying. In another method, this process may be repeated any number of times to achieve the desired fiber/filament properties.
  • the type of coating may change each coating performance, such as a silicone coating followed by a talc final coating or any combination thereof.
  • the fiber/filament coating thickness is measured by noncontact laser measurement in combination of optical vision system which monitors and records each length of fiber/filament at desired intervals.
  • Such fiber/filament configurations may include an external fiber/filament wrapping of polyester, nylon, cotton, or other suitable fibre as the fiber/filament type requires.
  • the fibre outer wrapping occurs after the fiber/filament has finished its curing cycle in the curing oven (10) where the cured fiber/filament is spooled up prior to entering the merging head system (16).
  • the wrap operation may be accomplished without the use of an uptake spool and be performed continuously upon exiting the cure oven.
  • An alternative fiber/filament configuration may require the addition of a second elastomeric coating of natural rubber latex. In one method, once the perimeter fibre is wound on to the fiber/filament core the fiber/filament is coated to protect the fibre/fiber/fil ament unit.
  • the outer wrap fibre spool (14) is provided as a method of outer wrap fibre for the merging head and performs as a continuous feed supply with tension management.
  • the outer wrap fibre (14) may utilize cotton or silk, polyester, or nylon, and may be wrapped around the fiber/filament core with a specific number of wraps per inch and in some embodiments use a woven fibre sleeve. In some embodiments the wraps per inch may range from 1-WPI to 5-WPI and depend on the application of the fiber/filament and its suitability or performance.
  • the cured fiber/filament may then be wrapped with fibre prior to or after application of the fiber/filament coating as performed in the fiber/filament coating bath(s) (11).
  • the merging head (15) provides a method for the outer fibre wrap (14) to be properly wrapped around the fiber/filament core in a spacing appropriate to the final fiber/filament configuration.
  • the specification is wraps per inch (WPI) or may utilize wrap per millimeter (WPM).
  • WPI wraps per inch
  • WPM wrap per millimeter
  • the merging head (15) may be utilized to combine multiple fiber/filaments to form a single, multi-layer fiber/filament piece.
  • the multi-layer fiber/filament piece may then be wrapped with fibre to form a specific configuration.
  • the fiber/filament may be wrapped with one fibre or a multiplicity of fibres depending on the desired fiber/filament performance and application.
  • the finished fiber/filament uptake spool system (17) provides for a single or multiplicity of fiber/filaments to be wound onto a finish spool as a completed product suitable for packaging and shipping or as an intermediary transfer hold prior to additional production work.
  • the final product rubber fiber/filament, coated or uncoated, by one or more coat layers there is provide a pre-tensioning unit (18) to ensure finished spools are wound to a correct fiber/filament tension.
  • a further fiber/filament uptake spool system (19) like the above-described fiber/filament uptake system (17) may be added singly or a plurality.
  • an alternate finishing process(es) may occur at multiple locations throughout the process as described herein and in Figure 5 including but not limited to: 1- Prior to entering the final curing oven (10); 2- Post curing oven (10); 3- After the outer fibre wrap (14) is incorporated; 4- After the fiber/filament coating (11) has been applied to the fiber/filament; 5- After exiting the drying oven (12).
  • the natural rubber filament made from PENRL described in Examples 2 and 3 is based on a purified natural rubber latex that has been coagulated, dried, and formed into bales as a solid.
  • the solid rubber is compounded with specific chemical ingredients necessary to assist in producing a finished sheet ribbon that is thinly sliced into fiber/filaments.
  • the fiber/filament is formed by extruding a thin sheet of compounded PEN solid rubber (PENSR, 3) through an extruder (4, 4a) forming mold whereby the thickness may range from about 1.0mm to about 10.0mm and with a width of about 250mm to about 1,000mm and in a continuous length as defined by the production batch size.
  • the extruded sheet (8) is sliced into smaller individual fiber/filament portions by means of a sheet cutter that first forms a ribbon which is then feed into the fiber/filament cutting tool which cuts the individual fiber/filaments.
  • the cutting tool may be adjusted in such a manner as to provide the size of the individual fiber/filament portion.
  • the cutting of the fiber/filament portions may be accomplished prior to or post curing (7) depending on the desired performance of the fiber/filament portions.
  • the extruded sheet may be compounded as a solid, while in other methods a blowing agent may be used which imparts small bubble pockets providing a closed cell foam.
  • Both solid and closed cell foam rubber fiber/filaments formed from the sheet and ribbon method from a PENSR source material offer unique physical properties and performance characteristics as desired by the product application, for example, elongation (elasticity), modulus and compression set performance.
  • the PENSR is the significantly reduced levels of detectable total proteins whereby the total protein content is lower than 200ug/g, preferably lower than 100 ug/g, and more some specifications or applications, preferably lower than 50 ug/g.
  • a PENSR and/or PENRL are not available, other commercially available Hevea latex’ like those indicated in Table 1, Example 2, may be selected and coagulated to form a solid rubber feedstock including but not limited to other now commercially or in the future available natural rubber latex (or a type 1 latex) has not been clumped or flocculated or has had substantially all of the magnesium removed to produce a natural rubber fiber/filament with the present described physical properties.
  • the compound formula determines the physical properties and performance of the finished fiber/filament as designed for the end application. It is standard in art that the physical properties are defined as having a specific range, e.g., range of elongation (stretch), modulus, and recovery from elongation, durometer (firmness), color and other performance characteristics.
  • purified natural solid rubber or PENSR may be compounded (2, 2a) in a variety of ways to promote the desired physical and visual characteristics required for the end applications.
  • the following base formula is provided as a guidance and reference, but it will be clear to one skilled in the art of rubber compounding those modifications of the described formula are within the scope of the present invention.
  • Table 13 Base Formulation for Compounding Purified Natural Solid Rubber (PHR)
  • the base formulation above in Table 13 may consist of other agents or chemicals used to enhance physical and/or visual characteristics in the finished fib er/fil ament, e.g., see Table 12.
  • the formulation consists of at least a vulcanization agent, wherein said vulcanization agent is Sulphur at a weight concentration in said natural rubber set between 0.5% and 3.0%; a vulcanization accelerator and a vulcanization activator; an anti-tacking agent; an antioxidant agent; and a stabilization agent.
  • other properties for weather protection such as UV stability can be added accordingly for certain applications, and such is described above herein.
  • a blowing agent may be incorporated in the final batch mix with the curing agents.
  • the sheet extruded is held in a captured mold between heated plates until the blowing agent reaches the desired temperature and decomposes forming individual gas pockets.
  • the formula compound may replace sulfur-based cure agents with peroxide cure agents.
  • the compounding is performed in stages with ingredients added and mixed with an extrusion stage to remove entrained air.
  • This form is allowed to rest for a period ranging from about one (1) hour to twenty -four (24) hours prior to the addition of the curing agents.
  • the agents are added and mixed, then extruded to remove any entrained air pockets.
  • the curing agents are incorporated then the compound batch is placed into the sheet extruder.
  • the mix is performed in multiple stages: 1) A premix stage that masticates the solid rubber to reduce the original Mooney (viscosity) to a lower number suitable for mixing and compounding; 2) The fillers, stabilizers, process oils, clays, and colors are combined to form a batch; 3) The rubber compound is then extruded to remove air pockets and then allowed to rest; and 4) The preform mix is then remixed with active ingredients such as activators and curing agents, then extruded again to remove air pockets.
  • active ingredients such as activators and curing agents
  • the extruder unit (4) ordinarily consists of a reservoir hopper to hold an amount of compounded rubber at an appropriate temperature, internal high pressure ram assembly, connecting chamber from the reservoir to the extrusion head (4a).
  • the extrusion head may consist of one (1) small mold opening or a multiplicity of mold formers (FIG.9) that forces the compounded rubber through the opening or openings to form a thin sheet of desired width out of the forming head onto an intermediary table conveyor. The movement of the conveyor is synchronized to accommodate the extruder output to ensure the sheet flows, remains flat and does not bind or wrinkle.
  • the extruder forming mold may emboss fiber/filament deformation into the sheet or ribbons to assist in slicing of the fib er/fil ament portions. See Figure 7, where dimension A is performed by the extruder forming head or by a forming roller (FIG.11 A).
  • the forming mold imparts a shape on both top and bottom of the sheet and/or ribbon (FIG.1 IB).
  • the extruder head (4a) may be of the heated type or cold type depending on the sheet compound where such heated head assists to start the curing process and reduce the viscosity of the compound to aid in material flow through the mold head.
  • the sheet or ribbon may be formed between two (2) or more configured rollers to assist in shaping the individual fiber/filament cross sections.
  • the separation conveyor table receives the extruded sheet upon exit from the extruder.
  • the conveyor table moves at the appropriate speed in inches per minute to coincide with the extruded sheet speed.
  • the extruded (and uncured state) may be moved through an array of rollers to force the thickness of the sheet to become thinner and where required the sheet may be sliced widthwise to form a smaller width ribbon to assist in downstream handling.
  • a curing oven (7) is provided to fully cure, set, and vulcanize the fiber/filament in a finished condition.
  • the oven may be heated using electrical heating elements, UV lights, infrared lights and microwaves or a combination thereof two or more energy supplying methods depending on the cure chemical system selected during compounding.
  • the curing oven may have a temperature range from about 120C (248F) to about 150C (300F), preferably with a set point of about 130C (266F).
  • the fiber/filament will reside (dwell) in the oven for a period of time necessary to fully cure the fiber/filament latex compound and may range from about 5min to 20min, preferably, 10 minutes or for whatever time is necessary to effectively cure the fiber/filament of a certain thickness and for additional manipulation.
  • the curing oven is configured to have a multiplicity of rollers whereby the fiber/filament length is wrap around such a roller to increase the total length of the fiber/filament in the oven at one time and operates at such a speed to coincide with the time of the cure.
  • the cure oven may be several feet in length depending again on the application, with an average length of about 50 to about 100 feet in length.
  • the cured sheet and/or ribbon is presented to the cutting tool array (8) where the sheet and/or ribbon is sliced into the appropriate individual fiber/filament portions depending on the desired fiber/filament product and application.
  • the rubber fiber/filament sheet may be sliced into a width of about 0.15mm to about 50mm or more depending on product design configuration.
  • the fiber/filament width is dependent on the desired use or application of the rubber fiber/filament.
  • ribbon in 0.5mm increment, for example, 0.5mm increments, 1.0mm increments, 1.5mm increments, 2.0mm increments and the like. Further, that the width range may be wider 500mm and subsequently sliced into smaller width increments depending upon desired product design.
  • the fiber/filament coating bath (9) is provided to coat the fiber/filament to prevent the fiber/filaments from sticking together when wound on the finish uptake spool (11). Additional purpose is to provide a required finish offering low friction or other characteristics.
  • coatings include but are not limited to dry coating agents such as talc and wet agents such as silicone, paraffin, polymers and/or any combination thereof.
  • talc dry coating agents
  • wet agents such as silicone, paraffin, polymers and/or any combination thereof.
  • a silicone coating may be followed by a talc coating which may be further coated by another wet or dry final coating or any combination thereof to achieve a desired property.
  • the coated fiber/filament may exit a bath, be dried, and reenter a secondary coating bath prior to exiting and drying. In other methods, this process may be repeated any number of times to achieve the desired fiber/filament properties.
  • the fiber/filament coating thickness is measured by non-contact laser measurement in combination of optical vision system which monitors and records each length of fiber/filament at desired intervals.
  • the drying oven (10) is utilized to dry and finish the fiber/filament coating system and may use forced warm air in a configuration typical to drying typical coating systems whereby heated air flow is required.
  • the finished fiber/filament uptake spool system (11) provides for a single or multiplicity of fiber/filaments to be wound onto a finish spool as a completed product suitable for packaging and shipping or as an intermediary transfer hold prior to additional production work.
  • the source material is a PESNR, it is dissolved using a range of solvents to form a solution which can be further compounded e.g., additional chemicals, fillers, curing agents and the like to form a final fiber/filament forming solution that is conductive.
  • Electrospinning technologies use electric force to draw charged fiber/filaments of polymer solutions or polymer melts, for example, natural rubber fiber/filament, into fibre diameters in the order of some hundred nanometers.
  • Electrospinning shares characteristics of both electro spraying and conventional solution dry spinning of fibres. Electrospinning has advantages over extrusion or other processes described above or elsewhere because it does not require the use of coagulation chemistry or high temperatures to produce solid fiber/filaments from solution. Thus, making the process particularly suited to the production of fibres.
  • Electrospinning is a simple electrohydrodynamic process used to produce fibres. It produces fiber/filaments, fibres and fibrous membranes which are employed in a wide range of applications, from tissue and/or material engineering, drug delivery to energy conversion and storage. Electrospinning uses a high voltage applied to a liquid droplet or solution, which causes the liquid becomes charged and electrostatic repulsion counteracts the droplet surface tension thereby stretching the droplet and at some critical point a stream of liquid erupts from the surface at the discharge site or Taylor Cone. The range of these fibres is 100 of nm to 10's of pm and the fibres are typically collected in the form of a non-woven membrane.
  • the geometry of the Taylor Cone can be modified to suit the desired fiber/filament size, purpose, or application.
  • the Taylor Cone geometry is governed by the ratio of surface tension to electrostatic repulsion.
  • Figure 15 shows one method for using electrospinning technology to form very small diameter natural rubber fiber/filaments.
  • the fiber/filaments or fibres discharged at the site of the Taylor Cone (C) are attracted to the forming plate (or collector, A) opposite the cone, is negatively charged and moves in three axis (X, Y & Z) to collect the fiber/filament fibres and arranges them according to the desired design features, e.g. as a non-woven flat membrane.
  • the solid rubber is mixed with a non-polar solvent or mixture of solvents suitable to dissolve the rubber forming a solvent/rubber solution.
  • This solution is then forced through a series of small openings in a forming head or spinneret.
  • the forming head is elevated to a height which allows the ejected solution to be pulled by electromagnetic conductivity downward through a heated chamber, through the Taylor Cone (C) whereby the fiber/filament fibre length is collected on a forming collection plate (A) which can move in three axes.
  • the forming plate (A) has a by-pass configuration (B) which is still negatively charged to attract the fibre leaving the Taylor Cone (C), but by-passing collecting on the forming plate and passing directly through to a curing and drying oven (D) where the fiber/filament fibre is solidified and wound.
  • the solvent portion of the solution begins to evaporate causing the fiber/filament to become solidified (D).
  • the evaporating solvent is removed from the chamber and recovered by condensation for reuse.
  • the fiber/filament length at the bottom of the heated chamber is eliminated of solvent forming a fiber/filament capable of being maneuvered into and through a washing bath.
  • the fiber/filament diameter is determined by the amount of solution discharged by the forming head, the length of the heated chamber, the speed in which the fiber/filament solution drops in addition to the starting solution viscosity among other solution and equipment parameters.
  • the fiber/filament As the solvent reduced fiber/filament is pulled by the roller arrays through the washing bath the fiber/filament enters a curing oven to ensure the polymers become cross linked and the fiber/filament’ s physical characteristics improve. As the fiber/filament is cured the equipment provides for additional processes such as coatings, fibre wrapping and wind up to finish fiber/filament uptake spools.
  • various solvents or mixtures can be used to convert the solid natural rubber to a liquid solution including but not limited to cyclopentane, hexane, cyclohexane and/ or toluene.
  • suitable nonpolar solvents may be utilized.
  • a ratio of solvent to solid rubber by mass can be identified which provides enough solvent to effectively reduce the rubber to form a viscose solution.
  • other additives that improve fiber/filament elongation, tensile, recovery after elongation, compression set, color retention, and other specific characteristics may be added to the solution as well.
  • the solution may contain carbon nano tubes and fibres which improve electrical conductivity while enhancing the physical performance of the fiber/filament fibre characteristics.
  • modification of the spinneret and/or the type of solution can allow for the creation of fibres with unique structures and properties.
  • Electrospun fibres can adopt a porous or core-shell morphology depending on the type of materials being spun as well as the evaporation rates and miscibility for the solvents involved. For techniques which involve multiple spinning fluids, the general criteria for the creation of fibres depend upon the spinnability of the outer solution.
  • coaxial, emulsion, electroblowing and ablative electrospinning technologies are contemplated. See the world wide web description for electrospinning, en.wikipedia.org/wiki/Electrospinning.
  • Coaxial electrospinning is a dual-solution feed system which allows for the injection of one solution into another at the tip of the spinneret. More advanced setups, such as a triaxial or quadaxial (tetra- axial) spinneret can be used with multiple solutions.
  • Figure 16 shows the crosssection of a coaxial electrospun fibre or fiber/filament.
  • a coaxial forming head or spinneret is utilized with a compounded solid version of the PESNR is forced and presented to the flow of solvent which dissolves and ablates the solid rubber and is pulled towards the collection plate below the forming head.
  • solvent dissolves the coaxial solvent flow creates a fiber/filament as it washes over the solid material.
  • Both the solvent and the material are formulated to be electrically conductive. As the fiber/filament is formed downward the carrier solvent evaporates causing the filament to solidify.
  • an emulsion electrospinning technology can be utilized.
  • emulsions can be used to create core shell or composite fibres.
  • a water phase and an immiscible solvent phase are mixed in the presence of an emulsifying agent to form the emulsion.
  • Any agent which stabilizes the interface between the immiscible phases can be used including but not limited to surfactants and even nanoparticles have been used successfully.
  • the electrospinning process the emulsion droplets within the fluid are stretched and gradually confined leading to their coalescence.
  • PE solid rubber emulsions may be used to form a continuous length of filament by a combination of electrospinning and pneumatically assisted/forced discharge at the nozzle forming head to form the filament.
  • the fiber/filament discharged by the forming head spinneret rapidly converts from a semi solid, gel-like or solution form to a more solidified material that is easier to handle due to its firmness.
  • rapid curing agents may be selected for this application including but not limited to a sulfur cure system such as a sulfenamide (TBBS) with TMTD, or MBTS /thiuram with the ultrafast accelerators.
  • the curative agent may also be a UV rapid curing system suitable for a non-polar solvent system, a water-based latex-like system or combination thereof as would be the compound for sulfur-based agents.
  • a curing chemistry to crosslink the rubber to obtain the optimum elastic and strength properties of the rubber can be achieved.
  • the fiber/filament compound may contain a range of purified natural rubber content (PNRC) from 1% to 100% as a base compound reference using Parts per Hundred Rubber (PHR) as the defining compound metric.
  • PNRC purified natural rubber content
  • PHR Parts per Hundred Rubber
  • the compound may include rheology agents to modify the flow of the fiber/filament compound through the forming head spinneret helping to form a drawing cone shape.
  • the compound contains fillers, short and long nano-fibres, nanotubes and other fillers which provide additional physical strength, production handling characteristics, including electrical conductivity necessary to effectively attract and excite the compound through the forming head towards the collection forming plate utilized for non-woven fibre sheets or fabrics and a collecting plate with by-pass opening for continuous forming of fiber/filament.
  • the by-pass collector plate FIG.
  • B) opening may in some embodiments be ringed by electromagnets which attract or repulse the fiber/filament as it passes through the plate opening in order to control the flow of the fiber/filament allowing it to be drawn through from a liquid like material, become solidified and firm which is required for a continuous formation length of fiber/filament.
  • Control of the electromagnets is performed by a control unit and computer with necessary switching circuitry and software.
  • the compound containing fillers necessary to impart electro conductive characteristics may be compounded in such a manner as to be immiscible with the base rubber mixture for the purpose of removal and washing as secondary stages where such fillers may detract from the desired end product’s performance characteristics.
  • multiple compounds may be utilized to create a coaxial fiber/filament design whereby the center core is one material, the outer coating is a different material and as such continues to the extent of the forming head spinneret is capable of.
  • the coaxial fiber/filament may undergo post-pulling coatings.
  • the center core may be of PNR or other while subsequent layers or coatings may be of similar or dissimilar material compounds depending on the desired physical performance characteristics.
  • the final layer coating may be defined as a dissolving or eluding medicines and be applied to the fiber/filament during the discharge of the forming head spinneret compounds and/or by downstream processes.
  • a wide variety of coating types may be utilized that control the rate of elution while offering protection from thread sticking during mat or fabric formation and/or during continuous fiber/filament formation.
  • the protective coatings may be washed off prior to final product production whereby a protective coating is undesirable.
  • the fiber/filament is produced using a coaxial forming head spinneret or postproduction coatings, the center core material is washed out forming a hollow fiber/filament with a central void.
  • a hollow fiber/filament with a central void.
  • Such hollow voids act as capillaries to locomote liquids, molecules in multiple manners whereby the certain sized molecules fluids or liquids may be blocked while smaller sized fluids are allowed to pass.
  • the void is produced by washing out the center fibre.
  • Latex threads are produced by continuous extrusion of compounded latex into a wet coacervant (aqueous phase rich in macromolecules such as polymers, proteins and the like) bath (e.g. about 20 - 40 % acetic acid) and followed by washing with hot water, drying at 60 - 80°C in hot air and vulcanized at about 120 - 130°C in hot air.
  • a wet coacervant aqueous phase rich in macromolecules such as polymers, proteins and the like
  • the vulcanized thread is then passed through a bed of talc and wound on to bobbins or drums and post-cured at about 60°C in hot air for about 24 hrs.
  • thread and filament are interchangeable.
  • the latex should be free of nonrubber constituents, including the PENR or PNR described herein. It is noteworthy that a non-PENR may not provide the fine denier filaments with similar properties as those filaments made using purified natural rubber.
  • the PENR is remarkably different than other commercial forms of NR on the market and is distinguished from other non-PENR or concentrated forms of NR. Refer to Example 2.
  • natural rubber latex compounding will depend in part on the type of NR used.
  • the general compounding formulation should have minimum number of additives in solid form and dispersions of compounding ingredients should be very finely grounded or milled during the initial mixing or ball milling process. It is also preferable that latex compounding dispersions be free from air bubbles / frothing to reduce or eliminate air entrapment. Before extrusion, remaining or existing air bubbles in the latex compound may be passed through a very fine mesh and allowed to de- aerate by application of partial vacuum or other means to remove air bubbles. Coacervant (acetic) bath
  • Acetic acid a weak monocarboxylic acid
  • Other weak acids (deprotonate) that are soluble in water may be substituted and boiling or heating temperatures may vary in view of the property of the weak acid.
  • the outside surface of the coacervants may form a thin-walled rubber film on the surface while the interior latex compound is still in fluid form or phase.
  • saline solutions may be preferred for thicker diameter filaments as they effect rapid setting.
  • the external skin formation on the latex filament is immediate. This skin acts as a semi-permeable membrane and solidification of the filament may be accelerated by water that is lost from the filament.
  • the coacervated batch should be well monitored and controlled throughout the process as consumption of acetic acid will change the milieu of the bath.
  • the extrusion nozzles are made from boro silicate glass capillaries with accurate dimensional control, which are then fused into wider glass delivery tubes.
  • Several sets of nozzles of different bore sizes are used as per the finished product, diameter requirements.
  • the exact size of diameter of the extrudate depends on parameters that include but are not limited to the nozzle radius (r-cm ), nozzle length ( 1-cm ), di (density of latex compound), d2 (density of resultant thread), h (pressure in cm of the compound at which the latex is extruded), q (the viscosity of latex compound in centipoises, s (the factional solids content in the compound and v (the speed in cm/sec at which the thread is delivered from drying and curing belts).
  • the diameter D (in cm) of the circular cross section of the latex filament delivered from the nozzle can be described using the following equation.
  • This equation indicates the factors to be controlled to obtain latex filament of given size from a particular size of nozzle.
  • Viscosity of the latex compound should be well controlled for total dimensional control of the product.
  • the filaments are passed through a hot water bath where water-soluble impurities are leached out.
  • the filament is strong at this stage and is subjected to a stretching process to determine the final diameter.
  • the filament is then carried to a hot air chamber for drying and vulcanization.
  • the hot air chamber has a drying zone maintained at approximately 70°C and the vulcanization zone is at about 125 - 130°C, although temperatures can vary in view of the compounding mixture and the purity of the PENR. Between the two zones one more zone is maintained at intermediate temperatures between about 70°C and 120°C.
  • the total time in the vulcanizer will depend on the diameter of the filament, typically between 5 to 7 minutes. However, the filament should preferably be thoroughly dried before it reaches the vulcanization zone.
  • the filament is then passed through a bed of talc and is inspected for defects on an inspection table as part of the continuous process before it joined to form a 40-end ribbon or wound on bobbins or drums under slight tension.
  • the ribbons, bobbins or drums are finally post cured at about 60°C in hot air ovens for 24 hr. to complete the cure cycle.
  • modulus, tensile strength and elongation The relationship between modulus, tensile strength and elongation is complex and depends on the specific materials. As materials become stiffer and stronger (modulus and tensile strength) it affects the strain or elongation, which is measure of how much any material can stretch or deform before breaking. Material microstructure and processing will affect this, but for this application: When the modulus and tensile strength go up, elongation goes down; and when modulus and tensile strength go down, elongation goes up.
  • Table 15 Comparison of Natural Rubber Fibers/Filaments Made from Unpurified and Purified Natural Rubber Latex [00355] Test trials: A (unpurified natural rubber latex, control) ; Bl- B3, Cl- C2; D; and El & E2 (purified natural rubber latex). The Denier is approximate as the size varies along the long filament, and for the above trials it is about 185-190 Denier.
  • the elongation (strain) values for the trials El and E2 are higher than trials Bl, B2, B3, Cl, C2 and D, due to changes in formulation and process conditions, demonstrating that physical properties of the filaments can be modified and for function and performance.
  • the increase in elongation values also corresponds to lower tensile strength and modulus, and that is observed in all the trials A through E.
  • Table 16 shows that the same count or denier filament can have different properties based on small changes to formulation and process conditions over periods of time.
  • Table 16 also shows that trials Bl and B2, having similar formulation and processing, do stabilize based on the parameters of modulus, tensile strength, and elongation.
  • Example 8 Fine Denier Natural Rubber Filaments compared to fine Synthetic Denier
  • Table 17 was compiled from specification sheets from the manufacturer. The ranges are reported by Lycra. The low value is the lower limit, and the higher value is what the product aims for. The values for the invention’s filament are from Table 15. Table 17 shows that the elongation of Lycra goes up as the denier goes up (count goes down). Comparing 180D Lycra to 190D natural rubber, the natural rubber filament has a greater elongation (strain) range (delta 224), even if accounting for the higher denier, than Lycra spandex (delta of 137 for 180D-IM732 LYCRA). This states that fine natural rubber filaments have unique properties not duplicated by synthetic fibers.
  • Table 18 compares the tensile strength of the invention’s natural rubber filaments compared to Lycra fibers. Again, even accounting for different deniers, the tensile strength of 180D Lycra is higher (stiffer) compared to 190D natural rubber filaments, which is lower with a range between 175-330, but after 14 days stabilizes to 383. Thus, there may be applications where substituting spandex for natural rubber filaments of the invention may be suitable, and other applications where one or the other is best suited.
  • the objective of the invention was to produce never shown a fine natural rubber filament for various uses. It was not necessarily just to substitute or replace spandex or other PU or petroleum based fine fiber, because the properties for a natural vs synthetic product in this instance are significantly different.
  • natural rubber filaments are made from purified natural rubber latex.
  • formulation and process changes with regular natural latex may be used to accomplish the same fine denier natural rubber filament.
  • Spandex type fibers are different from the fine denier natural rubber fibers described herein, even if in some instances they can be used interchangeably in certain applications.
  • Spandex are made up of numerous polymer strands, whereas the invention described herein is one long continuous filament.
  • Spandex is composed of two types of segments: long, amorphous segments and short, rigid segments. In their natural state, the amorphous segments have a random molecular structure. They intermingle and make the fibers soft. Some of the rigid portions of the polymers bond with each other and give the fiber structure. When a force is applied to stretch the fibers, the bonds between the rigid sections are broken, and the amorphous segments straighten out.
  • spandex Other drawbacks of spandex include: 1) heat sensitivity. Melting temperature of spandex is in the range of 175-178°C (from a solid to a liquid). At high temperatures the fibers can break down and lose their elasticity, and that is one reason spandex clothing should be washed in cold water and dried on low heat settings; 2) Sensitivity to ultraviolet radiation causing fibers to again degrade or lose their stretch over time. Spandex clothing should be stored away from direct sunlight; 3) Sensitive to chemicals like chlorine and certain oils, causing it to lose stretch and weaken; and 4) Pilling. Due to friction and abrasion, spandex fibres can pill (small balls on the surface of clothes).
  • Natural rubber is very thermostable. Natural rubber begins to melt at high temperatures, aboutl80 °C (356 °F). And once it is processed and vulcanized, it does not melt (from a solid to a liquid), which is a unique property of natural rubber and natural rubber products. At super high temperatures above 199°C (390°F) and depending on the vulcanizing agent and other fillers in the formulation, it may start to break down (e.g., burning rubber). Hence, fine denier natural rubber filaments have improved high heat, thermoset properties and applications that allow for high heat processing or finishing such as textile production. For example, elasticized fabrics like denim and cotton are excellent applications for natural rubber fibers.
  • fine denier natural rubber filaments can withstand high heat including higher heating setting temperatures and in textile production, e.g., high heat thermoset temperatures during finishing to control shrinkage and other properties of elastic yarns that make elastic fabrics or textiles.
  • high heat thermoset temperatures during finishing to control shrinkage and other properties of elastic yarns that make elastic fabrics or textiles.
  • the fine natural rubber filaments of the invention are an excellent option.
  • Figure 20 shows a cone of about 200g of uncovered 200D natural rubber fibers/filaments made by the methods described herein. Filaments are individually extruded or spun and then grouped together side by side to form a ribbon, e.g., 40 filaments are common.
  • the filaments of FIG. 20 can be used to make any of natural or synthetic (e.g., polyester) yarns made from 200 Denier (or 150 count) using a conventional ring-spinning or air-jet spinning process or similar methods.
  • natural or synthetic e.g., polyester
  • Denier or 150 count
  • Spinning is the process of producing yarns.
  • Yams made with spandex/lycra are composed of a plurality of spandex fibre (aka plies) which when they break due to abrasion, laundering, use (friction), normal wear and tear etc. they become easily tangled and the threads over time clump, causing surface imperfections on clothing called pilings or bubbling.
  • Synthetic fabrics are more likely to pill than natural fabrics. Materials including but not limited fabrics and fibres made from or include polyester, acrylic, nylon, rayon, and spandex.
  • Spun yams or yarns made from short fibres produce: i) a dull or a yarn with no luster and fuzzy look; ii) linting; iii) more absorbent; iv) pill; and v) complex manufacturing process.
  • Advantages of yams made with natural rubber filaments compared to stable fibre yarns are: i) natural rubber filaments are smooth, continuous, even and slippery to the touch and are not as textured; ii) does not require twisting or false twisting to impart strength and durability; iii) excellent durability and strength; iv) optionality to twist to control the fibers, modify their luster and create texture, and/or reduce the tenacity of the yarn and make the yam leaner (i.e.
  • Natural rubber filaments such as the natural rubber filaments made from PENR have longer length (or higher aspect ratio - length greater than its diameter or width) and provide filament with increased strength and durability and resistant to wear and tear, which translates into the ability to resist deformation or creep under loads and higher fatigue endurance with minimal compression.
  • the higher aspect ratio of natural rubber can improve strength and resilience of products.
  • Example 9 ElastomeRic Natural rubber fibre/filament formulations having 70-80% natural rubber content
  • Natural rubber fibers have about 80% or more natural rubber composition.
  • the invention for the first time demonstrates that natural rubber fibers can be produced with less than 80% natural rubber composition and produce a fiber that has the same physical properties as that of fibers with 80% or more described herein including but not limited to comparable elongation, tensile strength, and modulus.
  • Table 19 A-C describe formulations of a natural rubber filament with less than 80% natural rubber content.
  • any of the ingredients in Tables 18 A-C, and/or equivalents thereof can be modified and thereby change the total natural rubber content of the filament.
  • the titanium dioxide dispersion or equivalents thereof can be changed to modify the natural rubber content.
  • the Dixie Clay or equivalents thereof can be changed to correspondingly change the natural rubber content.
  • One skilled in the art with the formulas provided in Table 18 will know how to offset and vary the below ingredient concentrations to provide for a natural rubber fibre with less or more than 80% natural rubber content if desired.
  • the natural rubber latex contents in Tables 18 can be a mixture of pre-vulcanized latex and unvulcanized latex to reduce dye swell during the extrusion process and obtain a filament with more consistent diameter measurements throughout the filament.
  • 30% to 80% prevulcanized latex mixed with unvulcanized latex will reduce dye swell and help stabilize the filament and improve physical properties and performance.
  • natural rubber filaments as provided herein are biodegradable.
  • a ribbon consisting of 40 filaments (“40 ends”) was provided to an independent lab specializing in biodegradability studies. Each test specimen was weighed prior to burial. The test samples were moistened and then buried separately in an experimental container with microbially active soil (test soil) and incubated in standard indoor conditions. The microbially active soil was endured by the degradation of the control material that was 100% cotton sample with 100% mass loss. The test samples were removed and cleaned after 3 months and 9 months. The degradability of the test items was determined by the mass loss in aerobic biodegradation and compared to 100% mass loss of a 100% cotton control sample.
  • Table 20 is the result of an independent biodegradability study by Hohenstein of a ribbon with 40 ends or 40 filaments (not separated) showed that about 3-4% mass loss was degraded by 3 months, about 25% mass loss was observed at 9 months, and about 43% mass loss was observed at 12 months. In view of the 3, 9 and 12-month test results, it is expected that 90% or more mass loss will be reached after a total of about 24 months. All ecotoxicological tests have been passed.
  • Example 10 Elasticized fabric production with fine natural rubber fiber
  • Elasticized fabrics are used for a wide range of applications including sportswear apparel, fashion apparel ( jeanss etc.), intimate apparel (under garments etc.), socks, high-performance materials, swimwear and the like.
  • most of the elasticized fibers, threads and/or filaments or their covered yarns are synthetic (not natural, not plant-based, or bio-based) like spandex, elastane, LYCRA, or equivalents thereof made from polyurethane or polyolefin materials.
  • Applicant has produced for the first time a light-weight elasticized denim as described in Table 20.
  • the denim is 96% cotton and 4% natural rubber filaments, making it 100% natural product denim that should be biodegradable in view of the biodegradability of the natural rubber filaments in Example. 9, Table 19, and the same study using 100% cotton as a control that had 100% mass loss by 3 months.
  • Publication W02020084359 (“Candiani”) comprises a denim fabric cotton at a weight percentage of at least 50% and an elastic natural rubber fiber of polyisoprene 1 ,4-cis elastic yam with natural rubber content higher than 80%.
  • the embodiments herein are distinguished from Candiani since fine natural rubber filaments were not, and still not, available at the time of filing of the Candiani.
  • Candiani describes a traditional ring spinning technology for making yarns with different draft, which is just the ratio of linear speeds of the front rollers and delivery rollers which inserts the twist, to make the elasticized yarn. But controlling the draft with the front roller is not novel but ordinary depending on the fibre type. One skill in the art understands that the higher the draft, the more the fibers are attenuated, and the finer the fiber; but too much draft can cause the yarn to break and become weak.
  • Candiani describes an “an elastic thread having a linear mass density set between 50 dtex [45 denier] and 1000 dtex [900 denier].” However, nothing but less than 110 count or 120 count (or about 377 or 317 Denier) natural rubber fiber is even commercially available. That is, until the 150-160 count (or 203 to 178 Denier) fibres/filaments of the present invention.
  • Candiani also describes a natural rubber filament that has “polyisoprene 1,4-cis content larger than 80%”.
  • the embodiments of the invention also provide for the first time fine natural rubber filaments with polyisoprene 1,4-cis (or more commonly cis 1, 4 polyisoprene) content greater than 70% or less than 80% natural rubber, as well as filaments greater than 80% cis 1, 4 polyisoprene (Table 18).
  • the denim by Candiani is a heavy weight denim greater than lOoz, or 1 loz, or 12 oz, or 13 oz or more, because the only filaments available are a 110 (377D) or 120 count (317D), and not fine filament as the invention (150 - 160 count or about 180-200D). This may be due to using a bigger in diameter fibre/filament of Candiani whichrequires more cotton or other natural fiber to cover the filament completely (prevent grinning or exposed rubber), and thus the required drafting of VI, V2 and V3 as described in Candiani FIG.1. The extra drafting adds more to the total weight of the denim. Using more cotton fibres to natural rubber also changes the performance of the fabric.
  • the fine natural rubber filaments provided herein provides for the first-time production of elasticized yarns and fabrics that have not been possible because existing commercial natural rubber filaments are simply too thick or not sufficiently fine, and therefore the fabrics and garments too heavy for at least denim apparel applications.

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Abstract

In alternative embodiment, provided are high performance fine natural rubber filaments derived from a purified (or substantially purified) natural rubber and comparable or better in performance as compared to spandex including improved thermostability. Also provided are methods of making yarns from the filaments using various methodologies. Fine natural rubber filaments are used in textile applications including medical textiles, automotive textiles, geotextiles, protective textiles, sportswear, and composites.

Description

FINE DENIER RUBBER FILAMENTS COMPRISING NATURAL RUBBER AND METHODS FOR MAKING THEM
RELATED APPLICATIONS
This Patent Convention Treaty (PCT) International Application claims the benefit of priority under 35 U.S.C. § 119(e) of U.S. Provisional Patent Applications Serial No. (USSN) 63/389,204, filed July 14, 2022; USSN 63/396,558, filed August 9, 2022, and USSN 63/440,873, filed Jan 24, 2023. The aforementioned applications are expressly incorporated herein by reference in their entirety and for all purposes. All publications, patents, patent applications cited herein are hereby expressly incorporated by reference for all purposes.
TECHNICAL FIELD
[0001] This invention relates to polymer chemistry and natural products and uses and applications thereof. In alternative embodiments, provided are spandex -like fibers for filaments derived from natural rubber and/or purified natural rubber latex. In alternative embodiments, provided are methods of making composite yarns and fabrics from the fibers/filaments.
BACKGROUND
[0002] Textile fabrics are made of yarns and yarns are made of fibers (fibres) or filaments. The performance of a textile product, whether it is a pair of jeans or socks, is very much dependent on the fibers/filaments used. Physical properties of fibres / filaments are dependent on their structure (morphology) and molecular properties. [0003] Fibers are referred to as staple fibers that have a length between 2-46 cm. Fibres are natural or man-made, and man-made fibres are further categorized into organic and inorganic fibres. The Bureau International for Standardization of Fibres Artificielles (BISFA) defines or characterizes fibers by their flexibility, fineness, and high ratio of length to cross sectional area. Filaments on the other hand, have infinite length or of very great length or of a continuous length.
[0004] Natural rubber filaments in this invention were also referred to as natural rubber threads, for example, in priority applications, which is a more common textile industry term, but the more correct term is a natural rubber fibre, in particularly a natural rubber filament describing a continuous monofilament of the invention. [0005] Natural rubber filaments are commonly used in a number of products, including but not limited to elasticized fabrics for textile applications. It has long been produced in industry as an elastic filament in clothing such as socks, underpants and shirts and is produced by extruding wet liquid latex into an acid bath, which coagulates the rubber, forming a solid material with high elongation and return to original shape.
[0006] For decades rubber filaments came in two forms, bare rubber or covered rubber, the latter having a rubber core and wrapped or braided with thread or yam. Rubber filaments is produced by simply slicing thin ribbons of cured and colored rubber sheets. The rubber sheet is pulled across a series of knife blades slicing thin strips from the flat ribbon, which were then wound up on an uptake bobbin. However, one of the main disadvantages was that the core size or diameter was rarely uniform to each other throughout the length of a thread and were often square because they were simply cut from a rubber sheet or ribbon. The inconsistent and non-uniform diameter size and shape of the rubber filaments led to variable tension, which variations then resulted in irregularities in the rubber products made or incorporating the rubber threads including irregular surface of the fabrics in garments for example. [0007] There have been several reasons why a fine natural rubber fibre/filament like spandex has not been described or is commercially available including: i) natural rubber (polyisoprene polymer) has different molecular structure than their petroleum based polyurethane spandex polymers, affecting their ability to spun into fine filaments; ii) natural rubber has relatively lower tensile strength (Mpa) compared to synthetic spandex which again affect its ability to be spun into filaments without breaking or stretching excessively; and iii) different and more stages of processing and refinement are require for a fine natural rubber filament compared to spandex including the steps described above.
[0008] In comparison, modern synthetic fibers such as spandex are produced by wet or dry spinning of a combination of polymers containing both long and short polymer chains in varying percentages to suit the desired thread properties. Chemically, it is made up of a long-chain polyglycol combined with a short di- isocyanate and contains at least 85% polyurethane (PU). It is distinguished from the natural rubber filaments described herein because spandex fibers are made up of numerous (more than one or multi) polymer strands consisting of long, amorphous segments and short, rigid segments.
[0009] Current methodologies have their limitations including but not limited to: (i) the inability to control over cross section across the length (non uniform size and inconsistent); (ii) the limited capability to produce very thin cross sectional fiber (too thick); (iii) the increase “bundling” effect that occurs when the rubber fiber/filament is relaxed after stretching and causes areas of the fiber/filament to bunch up upon return to original size (garment shape); and (iv) the bunching of the woven fabric incorporating the rubber fiber/filament (surface fabric irregularities); (v) the limited environmental protection including but not limited to protection against UV, ozone, cleaning solvents and high temperatures (fibre breakdown); and (vi) they are comprised of multiple long and short fibers and not a continuous long or very long filament like that of the invention. The invention provides for improvements on these limitations and/or innovations around their limitations.
SUMMARY
[0010] In alternative embodiment, provided are natural rubber fibers and/or filaments and/or equivalents thereof from natural rubber latex, purified natural rubber latex or purified natural solid rubber (or cis- 1 , 4 polyisoprene) that are exceptionally consistent, uniform, and unambiguous physical properties. See Table 1. Purified elastomeric natural rubber (solid or latex form) is a purified rubber that during production has had over 98% to 99.9% of natural rubber harmful impurities, including proteins and other non-rubber content removed or “purified”. The PENR has increased performance characteristics and physical properties over existing commercial crude natural rubber latex including but not limited to higher total rubber content, substantially no or de minimus levels of non-rubber content or contaminants including proteins, improved green strength, improved tensile strength, improved viscosity, improved elongation modulus, improved heat and UV stability and the like. Thus, it is anticipated that a rubber fiber/filament made from or derived from such a high-performance rubber latex source material such as PENR will also produce equally uniform, consistent, and high-performance rubber products with similar physical properties.
[0011] Purification methods are described in W02022006393 by Applicant, which is incorporated by reference in its entirety.
[0012] As described in the Detailed Description, described here for the first time, is an elastic natural rubber (mono)filament and methods of making the same suitable for making yarns, weaving, and knitting woven and non-woven fabrics. U.S. Pat. Nos.
4,470,250, 4998403, 7134265, 6848151 describe processing. In alternative embodiments, provided are natural rubber fiber/filaments that exhibits similar or better performance to spandex, a synthetic non-natural polyether-polyurea copolymer. Methods for knitting or weaving that are used for a variety of end-use fabrics and are incorporated herein by reference in their entirety.
[0013] Embodiments of the invention include:
[0014] A rubber filament:
- comprising natural rubber that is between about 120 to 160 count or between 317 to 178 denier; comprising a natural rubber comprising less than 80% natural rubber content, or comprising natural rubber comprising less than 75% natural rubber content, or comprising between about 5% and 80% natural rubber content; wherein the natural rubber comprises cis- 1 , 4 polyisoprene; wherein the filament is made from purified natural rubber latex that is free (or substantially free) of more than 90% of non-rubber content; wherein the filament is made from purified natural rubber latex that is free of about 90% of proteins, or are free of between about 1% to 98% of proteins, or are free of between about 5% to 95% of proteins, or are free of between about 10% to 90% of proteins; wherein the filament is made from purified natural rubber latex that has reduced (or between about 1% to 90% lower, or between about 10% to 80% lower) levels of latex allergenic proteins; wherein the filament is made from purified natural rubber latex that has reduced (or between about 1% to 90% lower, or between about 10% to 80% lower) levels of latex proteins; wherein the filament diameter is equal to or less than about 0.2 mm, or is between about 0.05 and 0.2 mm; wherein the filament is thermostable; or wherein the filament is thermostable at high temperatures above about 180°C, or is thermostable at temperatures between about 180°C and 200°C; and/or wherein the filament is heat resistant;
In alternative embodiments, provided are methods for making a rubber filament, comprising any method of extruding the filament from a purified natural rubber latex substantially free of non-rubber content; or comprising extruding or electrospinning the filament from a purified natural rubber latex substantially free of latex proteins; or comprising a filament made from 10% to 90% prevulcanized natural rubber latex, or between about 20% to 95% prevulcanized natural rubber latex.
In alternative embodiments, provided are methods for making elasticized yam from a rubber filament as provided herein, comprising ring-spinning, rotor-spinning, twistless spinning, wrap-spinning, core-spinning and/or air-jet spinning, wherein optionally the yam comprises cotton and/or other natural fiber at a weight percentage of at least about 20%, or between about 15% and 95%, and optionally the yam is thermostable and/or heat resistant.
In alternative embodiments, provided are woven and knitted textiles comprising an elasticized yam as provided herein, or a rubber filament as provided herein.
[0015] A fine natural rubber filament that is about 120 to 160 count or 317 to 178 denier.
[0016] A natural rubber filament comprising less than about 80% natural rubber or content.
[0017] A natural rubber filament comprising less than about 75% natural rubber content.
[0018] A natural rubber filament comprising filaments as provided herein, wherein the natural rubber is cis-1, 4 polyisoprene.
[0019] The natural rubber filament of filaments as provided herein, wherein the filament is made from purified natural rubber latex that is free of more than 90% of non-rubber content. [0020] The natural rubber filament of filaments as provided herein, wherein the filament is made from purified natural rubber latex that is free of 90% of proteins.
[0021] The natural rubber filament of filaments as provided herein, wherein the filament is made from purified natural rubber latex that has reduced levels of latex allergenic proteins.
[0022] The natural rubber filament of filaments as provided herein, wherein the filament is made from purified natural rubber latex that has reduced levels of latex proteins.
[0023] The natural rubber filament of filaments as provided herein, wherein the filament diameter is equal to or less than 0.2 mm.
[0024] The natural rubber filament of filaments as provided herein, wherein n the filament is thermostable, or the natural rubber filament of filaments as provided herein, wherein the filament is thermostable at feverish temperatures above 180°C, or is thermostable at temperatures between about 180°C and 200°C.
[0025] The natural rubber filament of claims as provided herein, wherein the filament is heat resistant.
[0026] A method for making a natural rubber filament as of the filaments above, comprising any method of extruding the filament from a purified natural rubber latex substantially free of non-rubber content.
[0027] A method for making a natural rubber filament as of methods and filaments above, comprising extruding or electrospinning the filament from a purified natural rubber late substantially free of latex proteins.
[0028] A method for making a natural rubber filament as of methods and filaments above, comprising a filament made from 10% to 90% prevulcanized natural rubber latex.
[0029] A method for making an elasticized yarn from any of the natural rubber filaments as of methods and filaments above comprising ring-spinning, rotorspinning, twistless spinning, wrap-spinning, core-spinning and/or air-jet spinning.
[0030] The method for making an elasticized yarn from any of the natural rubber filaments as of methods above, wherein the yarn comprises cotton and/or other natural fibre at a weight percentage of at least 20%. [0031] The method for making an elasticized yarn as of methods and filaments above, wherein the yarn is thermostable.
[0032] The method for making an elasticized yarns as of methods and filaments above, wherein the yarn is heat resistant.
[0033] The method of using any of the yarns of methods and filaments above in woven and knitted textiles.
[0034] The method according to any of methods and filaments above, wherein the natural rubber is obtained from the group consisting of Hevea Brasiliensis, Hevea Guianensis, Hevea Benthamiana, Parthenium argentatum (Guayule), or Taraxacum koksaghyz.
[0035] The details of one or more exemplary embodiment of the invention, there is provided a method for making elastic yarns consisting of a PENR fiber/filament, are set forth in the accompanying drawings and whereby the PENR fibre is between ISOOO Denier the description below.
[0036] In another embodiment of the invention, there is provided a method for making woven or non-woven fabrics from elasticized yarns made from ring-spinning, rotor-spinning, twistless spinning, wrap-spinning, or core-spinning.
[0037] In another embodiment, advantages of the invention, there is provided a method for making a knitted fabric or a knit from elasticized yarns using weft or warp spinning.
[0038] The embodiments will be apparent from the description and drawings, and from the claims.
[0039] All publications, patents, patent applications cited herein are hereby expressly incorporated by reference in their entireties for all purposes.
DESCRIPTION OF DRAWINGS
[0040] The drawings set forth herein are illustrative of exemplary embodiments provided herein and are not meant to limit the scope of the invention as encompassed by the claims.
[0041] The accompanying drawings are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this specification, illustrate embodiments, and together with the description explain the principles of the disclosure.
[0042] FIG. 1 is a diagram describing typical natural rubber tree (e.g., Hevea braziliensis) latex emulsion and/or solid production.
[0043] FIG. 2 is a diagram describing the 4 principle steps of the purifying natural rubber latex of the present disclosure including obtaining the field latex and treating it with an anionic liquid and basic solution (Step 1); purifying the field latex by high speed centrifugation (Step 2); separating and collecting the heavy and the light phase (Step 3); and final treatment to produce the purified NR latex and / or solid.
[0044] FIG. 3 is a schematic diagram describing the four principal steps as described in FIG. 2 and principal components of field latex including rubber particles (light grey ovals), impurities dirt and other plant particles or debris (yellow squares), and other impurities such as fats, proteins, metals & oils (dark grey triangles).
[0045] FIG. 4A-B illustrate images comparing the color and clarity of the purified NRL emulsions (FIG.4A) and solid NR (FIG.4B) as provided herein as compared to other commercially available NRL and solid NR (ribbed smoked sheets of crude Hevea). The purified NRL as provided herein is clearer or colorless as compared to the other un-purified NRL. The purified solid NR is also substantially colorless or light-yellow tint (or off-white) as compared to the ribbed smoked sheets from unpurified NRL.
[0046] FIG. 5 is a diagram of an exemplary work progress flow.
[0047] FIG. 6 is a diagram of an exemplary work progression flow decision tree as provided herein.
[0048] FIG. 7 is a diagram of a process of producing rubber fiber or filament from natural rubber latex.
[0049] FIG. 8 is a diagram of a process of producing rubber fiber or filament from natural solid rubber.
[0050] FIG. 9 is a diagram of a process of producing rubber fiber or filament from purified or elastomeric natural rubber latex.
[0051] FIG. 10 is a diagram of a process of producing rubber fiber or filament from purified natural solid rubber.
[0052] FIG. 11 is a diagram of exemplars of extruding forming molds. [0053] FIG. 12 is another process of producing rubber fiber or filament from purified natural solid rubber.
[0054] FIG. 13 is a diagram of latex single (A) and multiple (B) extruder head configurations.
[0055] FIG. 14 are diagrams of cross sections of various rubber fibers or filaments. [0056] FIG. 15 is a diagram of a process of producing rubber fiber or filament from purified natural solid rubber using electrospinning technologies.
[0057] FIG. 16 is cross-section diagram of a hollow natural rubber fibre.
[0058] FIG. 17 is cross-section diagram of a nano or near-nano natural rubber fibre. [0059] FIG. 20 is an image of 200D elastomeric natural rubber fiber of the invention. [0060] FIG. 18-19 and 21-28 are diagrams from Sinclair, R. (Ed.) (2014) Textiles and fashion: Materials, design, and technology. Elsevier Science & Technology, Chapter 8-15, which is incorporated in its entirety be referenced and/or adapted to describe embodiments of the present invention. They describe different spun yarns and their applications and drawings of different spinning methods including ring-spinning (Like reference symbols in the various drawings indicate like elements.
[0061] It is to be understood that this invention is not limited to particularly exemplified systems or process parameters that may, of course, vary. It is also to be understood that the terminology used herein is for describing embodiments of the invention only and is not intended to limit the scope of the invention in any manner. [0062] All publications, patents and patent applications cited herein, whether supra or infra, are hereby incorporated by reference in their entirety to the same extent as if each individual publication, patent, or patent application were specifically and individually indicated to be incorporated by reference.
DETAILED DESCRIPTION
Definitions
[0063] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention pertains and as defined in ISO1382:2012 which defines standard rubber and vocabulary. [0064] In alternative embodiment, the term “antioxidant” refers to chemicals that are used to protect rubber articles against attack from oxygen (02).
[0065] In alternative embodiment, the term “antiozonants” refers to chemicals and / or waxes that “bleed” to the surface of a rubber article, to protect it against attack from ozone (03), and antiozonant ingredients. For example, antiozonant waxes are added to natural rubber to protect the fiber/filament from ozone by migration and blooming to surface which may also provide an increased level of lubricity.
In alternative embodiment, the term “antigenic protein,” refers to a protein that can induce the generation of antibodies and can cause an immune response in a subject who meets the antigenic protein.
[0066] In alternative embodiment, the term “biodegradable” as used herein means microbial degradation of carbon containing materials.
[0067] In alternative embodiment, the term “continuous vulcanization” refers to a process for vulcanizing NRL during continuous passage through specially designed energy transfer equipment.
[0068] In alternative embodiment, the term “core-spun” yarn, or “polycore” yam is created by twisting staple natural or synthetic fibres around a central filament core. Different spinning methods can be used to produce a core-spun yam.
[0069] In alternative embodiment, the term “count” in the textile industry is used to express how fine or coarse (or thin or thick) the yarn is. The numerical value is obtained by measuring how much length there is for a certain weight. There are different count systems including direct, indirect and cotton count systems. The indirect system is commonly used to convert count to denier is Count = (weight in grams of 1000 meters of fiber) / length in meters. Also, Count and Denier are inversely related: when the Count goes up, the Denier goes down and when the Count goes down the Denier goes up.
[0070] In alternative embodiment, the term “curing,” also known as “vulcanization,” causes the long polymer chains that rubber is composed of to become cross-linked.
[0071] In alternative embodiment, the term “dual-core” or “double-core yam” refers to a yarn having three components where a spandex fibre (such as Lycra, Creora and Inviya 1-300) and a multifilament (such as PET, PBT, PA and Lycra® . i o . T400) cores are covered with sheath staple fibers. For example, a dual -core yarn having an elastane or a fine natural rubber filament of the invention, surrounded by multifilament (e.g., LycraT400) and wrapped by sheath cotton fibers will achieve different elasticity and durability of fabrics, e.g., denim fabrics.
[0072] In alternative embodiment, the term “denier” (D) refers to linear density and is the mass in grams per 9000 meters (or 9 kilometers) of fiber or yam and used for synthetic and natural fibers. Denier and Count are both measures of the fineness of textile fibers. Denier = (weight in grams of 9000 meters of fiber) / 9000. The diameter of the fibre or filament will fluctuate over 9000 meters. For example, a 187D natural rubber filament described herein may be anywhere from a 178D-203D (150-160 count).
[0073] In alternative embodiment, the term “decitex” or “dtex” refers to a metric unit used for continuous filament yarn, defined as the mass in gram per 10,000 m. To convert dtex to denier, multiply 1000 by 0.9. For example, 1000 dtex * 0.9 = 900 Denier; 440 dtex = 396 Denier; 220 dtex = 198 Denier.
[0074] In alternative embodiment, the term “dimensional stability” refers to a fabric capable of retaining its original dimensions or shape of the fabric while being used for its required purposes (e.g., dyeing, finishing, washing or any other processes).
[0075] In alternative embodiment, the term “elasticity” refers to the property of rapid recovery of a material to its approximate original shape and dimensions after substantial deformation by a force and subsequent release of that force.
[0076] In alternative embodiment, the “elastomeric fibres” refers to any fibre or fiber, whether natural or non -natural, that can stretch 300% to 400% or more and return to their original size including but not limited to spandex, lycra and any natural fiber or filament described herein. IUPAC defines the term "elastomer" as a polymer that displays rubber-like elasticity.
[0077] In alternative embodiment, the term “elongation” refers to the length at breaking point expressed as a percentage of its original length (i.e., length at rest). For example, if a rubber component reaches twice its length before breaking its elongation is 100%; if it reaches three times its length before breaking its elongation is 200%; and if it reaches four times its length before breaking its elongation is 300% and so on. In addition, any of the methods described herein and in Figures, 2-19 and Table 5 can be modified adapted to provide for a filament with a desirable elongation factor. [0078] In alternative embodiment, the term “fiber” or “fibre” is a basic unit of a material. The term has been traditionally used with natural fibers, e.g., cotton fibers that are typically short and referred to as “staple length” that gives the length of individual fibers. Used herein, fiber and filament are interchangeable in context to the natural rubber fibers / filaments of the invention.
[0079] In alternative embodiment, the term “filament” is a continuous length of interlocking fibers, which can be spun from fibers or filaments and used in textiles for weaving, knitting, or sewing. The invention herein, “filament an” is a long continuous and indefinite monofilament or fiber. This is different from spandex like fibers that are made of twisting or forming together many short fibers or staple fibers to form a longer fiber and are not continuous monofilaments. Inventions here are long mono- fibers/filaments made from natural rubber and the terms “fibre” “fiber” and/or “filament” are used interchangeably.
[0080] In alternative embodiment, the term “filler” or “rubber filler” refers to materials or particles added to resin or natural or synthetic rubber that can improve specific properties. Non-black fillers for rubber exist including but not limited to calcium carbonate, kaolin clay, Dixie Clay, precipitated silica, talc, barite, wollastonite, mica, precipitated silicates, fumed silica, and diatomite.
[0081] In alternative embodiment, the terms “latex” or “natural rubber latex,” “crude rubber latex” or equivalents thereof refers to an “emulsion” or milky liquid, or non-vulcanized rubber, colloidal aqueous dispersion of a polymeric material that is extracted from any of various rubber producing plants and is the source of natural rubber.
[0082] In alternative embodiment, the term “latex compounding” refers to the addition of the certain chemicals to obtain certain or optimum physical properties in the finished product including but not limited to for example the chemistries to control the colloidal properties, to lower cost of goods, and/or to make it useable for use with available equipment. [0083] In alternative embodiment, the term “linear mass density” is the mass per unit length of any a one-dimensional object such as a string, wire, cable or in this invention a natural rubber fiber, it is expressed in kg / m or g / cm.
[0084] In alternative embodiment, the term “modulus” refers to a measure of stiffness under specified conditions of deformation, e.g., compression modulus or shear modulus, whichever applies. Modulus value desired depends on its application, e.g., modulus for a wetsuit will be different than modulus for denim, apparel, footwear, or upper soles of a shoe, for the same textile material. The formulation and method of making the same described herein can form the desired modulus for the desired application and product. It is expressed in Pa (pascals) megapascals, gigapascals, kilopascals, or Newtons (N) square meter, Nm2.
[0085] In alternative embodiment, the term “non-rubber” or “non-rubber content” refers to non-rubber impurities.
[0086] In alternative embodiment, the terms “protein content” or “total protein content” refer to the amount of protein in any sample. Warburg-Christian, Lowry Assay, and Bradford Assay, or FITkit® Hev b 6.02 that test certain latex allergens can all identify and/or quantify levels of proteins in an article, e.g., a finished good made from natural rubber.
[0087] In alternative embodiment, the terms “purified natural rubber”, “purified natural rubber latex”, “purified NRL”, “PNRL” or equivalents thereof, are used interchangeably, is a natural rubber latex that has been compounded to obtain certain physical properties or characteristics of a purified or premium NRL is 90% or more purified of contaminants, or about 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% free of other non-rubber contents including proteins or about 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% protein free. State another way, the invention provides for a natural rubber fiber that is more than 90% deproteinized. The fibers of the invention have the following physical properties: i) the total range of protein content is about 50 ug/g to about 200ug/g (see Table 2); ii) the total solids content (TSC) range is between at least 60% (see Table 1), depending on the process parameters and the desired TSC level for the process or requirements for a machine or industry or field; iii) the dry rubber content (DRC) is at least 60% (see Table 1); iv) the non-rubber content (NRC) has a range of about 0.01 to 1.0%, preferably less than 0.5% (see Table 1); v) the pH is a basic pH, for example, the pH is in the range of about 8.0 to 12.0 (see Table 1); vi) the viscosity of about 60% TSC centipoises (cP) in an uncompounded form ranging from 35 to 100 cP; and a viscosity of about 60% TSC cP in a compounded form ranging from 40 to 200 cP; viii) tensile strength of about 30 to 40 MPa (see Table 3); ix) Green strength of about 30-50 MPa (see Table 4); xi) Elongation percentage greater than 1300% (see Table 5); and xii) Modulus less than 1.3 MPa (very soft, see Table 6).
[0088] In alternative embodiment, the terms “parts per hundred rubber” or “PHR” and is the measurement unit used to distribute various uncured rubber polymer, carbon black and non-black fillers, plasticizers, age resistors, vulcanizing ingredients, activators, and other special purpose ingredients.
[0089] In alternative embodiment, the term “spandex” or “elastane” are used interchangeably, and both mean the same thing and are synthetic polyesterpolyurethane copolymer fibres that are known for their elasticity. Examples of spandex include LYCRA, CREORA and INVIYA 1-300.
[0090] In alternative embodiment, the term “spinning” to produce yarns including but not limited to: 1) “ring-spun” yarns, where the fibres are twisted around each other to give strength to the yarn; 2) “Rotor-spun” yarns, similar to ring-spun yarns, and made from short staple fibres that produce a more regular and smoother, though weaker, yarn than ring spinning; 3) “Twistless” yams where the fibres are held together by adhesives, not by the twist, and are often laid over a continuous filament core; and 4) “Wrap-spun” yarns where the staple fibres bound by another yarn, which is usually a continuous man-made filament yarn and can be made from either short or long staple fibres; 5) “Air-jet” spinning, a pneumatic method consisting of passing a drafted strand of fibers through one or two fluid nozzles located between the front roller of a drafting system and a take up a device.
[0091] In alternative embodiment, the term “spinning” is also used in production of mono-filaments and fibres from natural fibers including but not limited to: 1) dryspinning whereby a polymer and a solvent is extruded through a spinneret into an evaporating chamber and hot air causes evaporation of the solvent and solidifies the filaments; 2) wet-spinning or liquid-spinning whereby polymer powder is dissolved in a solvent and extruded through spinneret into a coagulant to form fibers.; 3) electro- spinning substantially as described in Example 5; and 4) melt-spinning whereby rapid cooling systems are used to transform melted base materials into long strands or filaments.
[0092] In alternative embodiment, the term “tensile strength” refers to how much force or stress, for example, a rubber material can withstand before breaking. The tensile strength of the rubber is expressed in the same units as modulus (Pascals) or pounds per square inch (psi). During this test, we pull the material up to the point of failure. In addition, any of the methods described herein and in Figure 2 can be modified adapted to provide for the invention with a desirable tensile strength value. [0093] In alternative embodiment, the terms “tensile modulus” or “tensile stress” refers to tensile stress at a given elongation.
[0094] In alternative embodiment, the term “thermal stability” or “thermal stable” to any thermal process performed to a fibre or fabric, for example in a steam atmosphere or a dry heat environment and remain its high performance (aka “heat setting”). In addition, any of the methods described herein and in Figure 2 can be modified adapted to provide for the invention with a desirable thermal stability.
[0095] In alternative embodiment, the term “thread” is a thin strand of yam used for sewing and a term associated with textiles and not natural rubber. Prior application uses of the term “thread” are replaced with “fiber” or “filament” or “fiber/filamenf ’ to describe the invention more accurately in the context of natural rubber and methods described herein.
[0096] In alternative embodiment, the term “type 1 latex allergy” or “immediate- type” or “IgE-mediated latex allergy” or equivalents thereof refers to an immediate upon contact hypersensitivity to natural rubber latex and is an IgE-mediated, or immediate type hypersensitivity reaction to one or more proteins in natural rubber latex. In one embodiment, the purified natural rubber filaments are made from purified natural rubber latex and have not been shown to cause immediate hypersensitivity or IgE-mediated response in those with type 1 latex hypersensitivity. [0097] In alternative embodiment, the term “type IV latex allergy” or “cell- mediate latex allergy” or equivalents thereof refers to a cell-mediate contact dermatitis (type IV) reaction or skin inflammation upon contact or sensitivity to chemicals used to make latex products, rather than to rubber proteins themselves. [0098] In alternative embodiment, the term “UV stabile” or “UV stabilized” or its equivalent refers to a stabilizer(s) to a polymer or polymer resin to allow it to protect the substance from the long-term degradation from UV light. Any of the methods described herein and in Figures 1 and 4-12 can be modified adapted to provide for the invention with a desirable UV stability.
[0099] In alternative embodiment, the term “yarn” refers to a linear and interlocked collection of filaments or fibres in a twisted state or bound by other means and possessing good tensile strength and elasticity properties. Fibres are processed in both pure and blended states, from both synthetic and natural materials. There are many different types of yarns including staple, continuous, novelty, industrial, high bulk and stretch yams. Yarns are further used in sewing, crocheting, knitting, weaving, embroidery, rope making, and the production of textiles.
[00100] In alternative embodiment, the term “staple yams” refers to a yarn formed from staple fibres. These are small fibres that can be measured in cm or inches. Except for silk, all natural fibres (such as wool, flax and cotton) are staple fibres. Staple-fibre yams can be subdivided and classified on the basis of fibre length, spinning method and yarn construction and classified as either short staple or long staple with lengths of between 10 and 500 mm with short staple fibre having a maximum length of 60 mm (cotton fibre is a short staple at about 25-45 mm) and long staple fibres having a length of more than 60 mm (wool fibre is a long staple at about 60-150 mm).
[00101] In alternative embodiment, the term “continuous-filament yams” are yarns that have high strength, uniformity and extruded e.g., through a spinneret. The number of orifices in the spinneret dictates the number of filaments in the bundle; and the diameter and amount of drawing provided will subsequently decide the diameter of the filament.
[00102] In alternative embodiment, the term “novelty yarns” refers to yarns that have decorative features and characteristics.
[00103] In alternative embodiment, the term “industrial yams” refers to those yarns that are functional, designed and produced to satisfy a specific set of requirements. [00104] In alternative embodiment, the term “high-bulk yams” refers to yarns that can be a staple or continuous-filament yam with normal extensibility but an unusually high level of loftiness or fullness.
[00105] In alternative embodiment, the term “stretch yarns” refers to yams that have high stretchability and cling without high pressure, good handle and covering power, e.g., Twist-heat set-untwist; Crimp heat-set; Stress under tension; Knit-deknit; Gear crimp.
[00106] In alternative embodiment, the term “vulcanization” refers to a range of processes for hardening rubbers, and “vulcanized rubber” refers to treatment of natural rubber with a vulcanizing agent, including but not limited to elemental sulfur, selenium, tellurium, sulfur compounds, peroxides, quinone compounds, amine compounds, resinous compounds, metal oxides and isocyanates. The most used vulcanizing agents are elemental sulfur and sulfur-containing compounds. The term “vulcanization” and “cure” are used interchangeably.
Methods for purifying natural rubber (WQ2022/006393)
[00107] Applicant is the first to describe the purification of natural rubber latex (and solid) and provide a commercial product that is substantially free of impurities and proteins (greater than 90%) while improving certain physical properties (e.g. tensile strength, elongation, modulus) and maintaining similar properties of unpurified or existing NRL (e.g. total solid or rubber content, pH, viscosity). Applicant’s publication WO2022/06393, Methods for making purified natural rubber and compositions, filed July 1, 2021 (PCT/US2021/040085) is hereby incorporated in its entirety by reference including the drawings.
Methods for detecting protein levels in natural rubber latex
[00108] One embodiment of the invention is to provide a purified natural rubber latex emulsion with greater than 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% and 99% of the total proteins removed. There are standard test methods for determining the levels protein present including but not limited to FITkit® Hev b 6.02 that test certain latex allergens. There are methods which rely on spectrometry where detection of single proteins are possible include high-performance liquid chromatography (HPLC) or liquid chromatography-mass spectrometry (LC/MS); antibody detection methods such as enzyme-linked immuno-absorbent assay (ELISA), which is particularly useful for detecting proteins down to pictograms per milliliter (pg/mL), or protein immune-precipitation technique, or immunoelectrophoresis, or Western blot. ASTM D5712 is a Modified Lowry Standard method and is used to quantify the total extractable protein content of a test article or product.
This method is not specific for latex proteins but will determine the total amount of protein from Hevea and other sources that are in the test item. However, extracting proteins from a test article is not efficient and any of the methods described herein and in Figures 2-19 can be modified adapted to provide for a NRL with a desirable low to exceptionally low to de minimus amount of total protein content.
Exemplary/ General Methods for Natural Rubber Fibers/Filaments
[00109] The finest or smallest diameter natural rubber fiber that is commercially available is a 20 -110 count (about 11305 to 204 Denier) and is: i) talcum coated; ii) powderless; iii) silicone coated and combinations thereof. Table 1: Product Specifications of Commercial Natural Rubber filaments
Figure imgf000019_0002
Figure imgf000019_0001
Figure imgf000020_0001
Table 2: Comparison of Product Specifications of Natural Rubber filaments
Figure imgf000020_0002
[00110] Prior to this invention, higher count (110 or higher) or small denier natural rubber filaments had not been described, produced and are not commercially available. Many skilled in the art assumed it was not possible to manufacture (extrude) a fine natural rubber fiber. The highest count (or smallest denier) filament is 110 count but the 100 count being the most common. Thus, this is the first time a 120, 140, 150 or 160 count (or about 317, 233, 200 or 178 denier) natural rubber filament has ever been described or produced.
Extrusion methods for making natural rubber filaments
[00111] In one embodiment, traditional extrusion methods are used for production of natural rubber or purified natural rubber filaments. Compounded latex is added to a wet coacervated bath (e.g., 20 - 40 % acetic acid, thickness depending) and followed by washing with hot water, drying at 60 - 80°C in hot air and vulcanizing at 120 - 130°C in hot air and repeated until the filaments are properly cured. The vulcanized filament is passed through a bed of talc and wound on to bobbins or drums and post cured at 60°C in hot air for 24 hr. [00112] After the coacervated batch the filaments are passed through a hot water bath where water-soluble impurities are leached out. The filament is strong at this stage and is subjected to a ‘stretching’ process to control the final diameter. The filament is then carried to a hot air chamber for drying and vulcanization. The hot air chamber has a drying zone maintained at approx. 70°C and the vulcanization zone is at about 125 - 130°C. Between the two zones one more zone is maintained at intermediate temperatures between 70°C and 120°C.
[00113] The total time in the Vulcanizer depends on the diameter of the filament (typically between 5 to 7 minutes). The filament is thoroughly dried before it reaches the vulcanization zone. The filament is then passed through a bed of talc and is inspected for defects on an inspection table as part of the continuous process. The filament is finally wound on bobbins or drums under slight tension. The bobbins or drums are finally post cured at 60°C in hot air ovens for 24 hr. to complete the cure cycle. Various other quality control tests are then carried out.
[00114] Figures 5 and 6 describe the Work Progression Flow of identifying, selecting and adapting methods for making natural rubber filaments as contemplated in the invention.
[00115] Rubber filament is currently being produced globally with primary density of suppliers located in Asia, and uses simple, low-cost equipment and production methods. However, most manufacturers of rubber filaments source crude field rubber latex as the material of choice. The reason for using field latex coincides with many of the other production strategies used by the industry, which revolve around costing pressures to provide large volumes of filament at the lowest price possible; and rubber filament is viewed as a commodity not a technology. Advancements in the production (technology) also revolve around economics with a focus on producing more rubber and rubber filament therefrom for less, and many of the desirable physical properties that are seen as limiting factors in weaving have gone unattended.
[00116] The present invention describes various alternatives as well as specific examples for production of natural rubber filament from natural rubber latex, solid or latex. Figures 3 and 4 describe basic methods for making rubber filament using NRL (FIG.3) or solid NR (FIG.4). For example, FIG. 3 shows a method of extruded rubber filament (ERT) production is produced by extruding compounded latex through capillaries into a bath of coagulant, and the coagulated wet filament is then washed, dried, and vulcanized to produce an elastic filament.
[00117] The present invention describes specific examples, for example as depicted in Figures 5 & 6 for production of rubber filament using a natural rubber latex (FIG.5) or solid (FIG.6) source material with the physical properties as described in Example 2 and referred to herein. The PENR, particularly, the PENR latex (PENRL) can be further compounded (chemicals added) to improve its stability, to change and / or achieve additional or desired physical properties.
Methods for making rubber fiber/filaments with desired physical properties [00118] In one embodiment, the viscosity of the NRL may be adjusted to a high level, and above that of typical latex used for dipping, to assist in formation of the rubber filament once injected into the coagulation bath and may increase in a range from 100 to 2,000 cP. See Figures 4 & 5.
[00119] In one embodiment, rubber filaments can be extruded in a variety of fib er/fil ament diameters ranging from 0.10 mm to 1.5mm. Additionally the filaments may be formed as a round, flat, oval, or other cross-sectional shape. Other methods of rubber fiber/filament production include slicing very thin filaments from a solid flat sheet or ribbon of procured rubber. Various surface coatings are used to prevent sticking and can be talc, silicon, or clay. Some filaments are produced with an outer wrapping of synthetic fibre such as polyester, nylon or silicone, or naturally derived fibre such as cotton, wool, bamboo, or flax, etc. Natural rubber filaments are also described in Deniers. There is also a correlation between the breaking strain, for example a 70-denier filament will be stronger than a 30-denier filament. Since the natural rubber filaments described herein are not synthetic fibres, the size, thickness, or diameter of the natural rubber fibre uses regular metric units, e.g., millimeter, centimeters. Still a correlation between the breaking strain for a natural rubber fiber/filament is analogous to that described above for synthetic fibres, i.e., the bigger the thickness or diameter of the natural rubber fiber/filament the stronger it is.
Methods of producing prevulcanized PENR for production of PENR fiber/filament [00120] In one embodiment of the invention, the PENR latex should be free from non-rubber constituents. The compounding formulation should have minimum number of additives in solid form. Dispersions of compounding ingredients should be very finely ground during ball milling. Dispersions should be free from air bubbles / frothing. Air entrapment should be zero or minimum during various compounding and processing operations. Before extrusion, the compound should be passed through a very fine mesh and then allowed to be degassed by application of partial vacuum. Removal of excess shipping ammonia is to be accomplished by stirring latex compound on a warming plate below a ventilated extraction system. Always use proper and effective personal protection equipment and adhere to all safety precautions and standards. Disposal of waste latex may be accomplished by freezing the material to a solid and disposing of per country/state regulations only.
[00121] The table below describes a compound mixture consisting of various ingredients. One skilled in the art will be able to vary the amounts of the ingredients based on the intended product application and field of use. For example, ammonia is described, but one skill in the art will appreciate that other substitutes like succinimide and phthalimide are available. Succinimide can be made from renewable resources for example. Similarly, there are substitutes for ingredients listed in Table 3A - 3B below including but not limited to substitutes for ZnO, ZDEC, Sulphur, KOH, and other stabilizers.
Table 3: Compounding Ingredients (formulas A & B)
Figure imgf000023_0001
[00122] Drying and curing the PENR fiber/filament in hot air may be combined as described above and varying the temperature and rate according to the physical properties desired and/or until the fiber/filament is properly cured. [00123] In other embodiments, the extruded fiber/filament, which is wet, is dried at about 84°C at about a rate of 35 meters per minute.
[00124] In another embodiment, the dried fiber/filament is cured at less than 120°C, e.g., 112°C to 115°C at about 60 meters per minute and this cycle is repeated, 2x, 3x, 4x, 5x, 6x and so on until the fiber/filament is properly cured.
[00125] The latex is contained in a stirred and jacketed mixing vessel and the compounding ingredients such as those described in the Table above are added. In one method, a mixing vessel with a heated jacket is used and hot water is passed through the jacket to heat the vessel. The duration of heating will depend on the desired degree of cross linking has been achieved, which can be determined by various quality control testing now available or later invented (e.g., solvent swelling, combined Sulphur analysis or by assessment of tensile properties), but for about 3 - 5 hr. at about 50 - 60°C. The latex compound is then cooled to room temperature and filtered or clarified centrifugally before use.
[00126] Prevulcanized latex is effective in small to medium sector dipped goods industries since further compounding of latex is not necessary or is limited to incorporation of desired pigments (e.g., manufacture of toy -balloons, medical goods, feeding bottle teats, etc.). The cross linking can be achieved by reaction with Sulphur, Sulphur donors (e.g., TMTD, DTDM, TETD) or by gamma radiation. The compounding formulations can vary depending on end applications. If ZDEC / ZDBC is present, ZnO is not necessary. (ZnO reduces the film clarity and may be substituted by ZnCCh to improve the same). For peroxide cross-linking, tert-butyl hydro peroxide and tetra ethylene pentamine are used. Maximum film clarity is obtained by using ZDBC alone. The cross-links found in Prevulcanized latex are predominantly polysulphidic (except for Sulfurless /Sulfur donor cures).
[00127] When the fibre is extruded into a water bath and out of the die the diameter of the fibres swells (die swell) and the diameter increases. In one embodiment of the invention, it is preferable to maintain or control the die swell such that the extruded natural fibre does not swell. There is an inverse relationship between the amount of accelerant added to the pre-vulcanization compound and the die swell. [00128] In one embodiment, prevulcanized latex reduces die swell by about 74- 80% on extrusion processes, providing smaller diameter and lower denier filaments. Prevulcanized latex also improves cure time and crosslink density.
[00129] Alternatively, prevulcanized latex can be blended with non-prevulcanized latex at 10:90, 20:80, 30:70, 40:60, 50:50, 60:40, 70:30, 80:20, 90: 10 and so on. Each blend will offer slight changes to physical properties.
[00130] For example, a pre-vulcanized compounded natural rubber latex that is 50% prevulcanized reduces die swell by 50% and so on. The preferred prevulcanization is greater than 40%, greater than 50%, greater than 60%, greater than 70%, greater than 80%, greater than 90%, about 100% depending again on the physical property desired and the application.
The sulfur to accelerator ratio during the pre-vulcanization process or even postvulcanization process has an impact on the crosslink density, hence modifications of the ratio of sulfur to accelerators may be necessary. Some exemplars include but are not limited to: (i) high sulfur at about 2.0PHR to 6.0PHR and low accelerator at about 0.2PHR to 0.50PHR; (ii) sulfur at about 1.50PHR to 3.0PHR and accelerators at about 1 0PHR to 2.75PHR; and (iii) sulfur is low at about 1.0PHR to 0.50PHR and accelerators are high at about 1.25PHR to 4.0PHR; or multiple combinations thereof with a shift towards lowering or increasing sulfur to accelerator ratio. Crosslink density alters as this ratio alters creating polysulfidic, disulfidic and mono sulfidic links. Accelerated sulfur vulcanizations are classified as conventional (CV, A/S = 0.1 = 0.7), semi -efficient (SEV, A/S = 0.7 2.5), and efficient (EV, A/S = 2.5 12), depending on the accelerator/sulfur (A/S) ratio, with the amount of both components being given in PUR.
Protective agents for natural rubber fiber/filament [00131] Antioxidants act as protective agents in latex compounds depending on the nature of the product and the applications including but not limited to how and the conditions for use of the product, storage of the product, desired durability or longevity of the product, rigidness or stretchability and other desired properties for the product’s intended use. For example, natural rubber latex vulcanizates compounded (mixtures) using about 1.0 PHR of Zn-dialkyl dithiocarbamate accelerators may not need further antioxidant protection unless the products are very thin or the use of the product is beyond normal practical use.
[00132] Antioxidants and anti-ozonants used in the invention include but are not limited to Wingstay L, BHT, Durazone 37, Nochek 4729, EPDM, liquid, TBPA 70, Naugard 445 and typically is not greater than 1.5%, is not greater than 1.75% or is not greater than 2.0 PHR in total. Again, one skilled in the art based on the use and application will understand that such other commercially available antioxidants and anti-ozonants now known or later discovered may be used in rubber compounding, and further modifications including type and concentration and time is within the scope of the invention.
[00133] Ozone waxes (which migrate and bloom to the surface to protect from ozone forms. Some wax types may even improve surface lubricity by providing a protective coating.)
[00134] Typically, two or more protectants are used to form a synergistic value and fuller protection. The following chemical types may prove to provide both antioxidant and antiozonant properties. See protective packages below.
[00135] The incorporation of many antioxidants in natural rubber latex compound is often difficult. The choice of antioxidant is particularly important when the product will be subjected to detergent washing (e.g., gloves).
[00136] Most commercial natural and synthetic rubber latex suppliers are sold with substances, which function as polymer antioxidants. For example, amine derivatives such as 2, 2, 4-trimethyl-l, 2-dihydroquinoline (oligomers) (or TMQ) and N-Phenyl- 2-naphthyl amine (or PBNA) are more powerful antioxidants against the effect of heat, light, and trace metals but these tend to cause discoloration as the produce ages. However, TMQ can be used for dark / black colored products where discoloration is not as noticeable.
[00137] In contrast, phenolic antioxidants are weaker against degradative forces but do not cause any discoloration and are commonly used in all latex compounds. The type and dosages of various phenolic antioxidants used for latex compounding may vary depending upon the end rubber product/application.
[00138] For example, monophenols including but not limited to Butylated hydroxytoluene (or BHT), Styrenated Phenol, alkylated hindered phenols, and Bisphenols including but not limited to 2,2’-Methylenebis(6-tert-butyl-4- methylphenol) analytical standard (CAS No.: 119-47-1) (or A/O 2246), Polybutylated bis phenols, and thio bis phenols. For polyphenols including but not limited to Wingstay L (a butylated reaction product of p-cresol and dicyclopentadiene), and Irganox 1010 - Tetrakis (methylene 3-(3,5-dibutyl-4 hydroxyphenyl) propionate) methane.
[00139] Different products and applications will require different types and amounts of antioxidants. Latex foam products such as carpet backings require antioxidants at 1.0 - 1.5 PHR amounts because the product demands longer service life or longevity (10 - 15 years), retention of cushioning effect to ensure long life for fibres, non-staining or slight discoloring characteristics, resistance to dyes (metal ions) and detergents (strong oxidizing agents), resistant to UV light and heat (longer drying conditions at high temperatures etc.). In contrast, latex dipped goods such as balloons, condoms, catheters etc. are thin-walled articles and hence need adequate protection.
[00140] Latex filaments as described herein, require highly non-staining and persistent antioxidants along with resistance to detergents and the recommended antioxidant amounts (phr) will depend again on the application and field of use. A few non-limiting examples include rubber fiber/filaments at about 0.5 - 1.0 phr Polyphenol and/or about 1.0 phr Styrenated phenol.
[00141] Additionally, the lifetime and effectiveness of the antioxidants can be enhanced by the addition of a UV absorber such as benzothiazole derivative (Tinuvin P) or hydroxybenzophenones, which are colorless.
[00142] Conventional amine or phenolic antioxidants are used with sodium (Na)- EDTA salt for the protection of unvulcanized latex compounds. The Na-EDTA salt acts as a metal ion-chelating agent for copper and manganese ions.
Stabilizing natural rubber source material through stages of production
[00143] To manufacture rubber goods from natural rubber latex component, it is necessary to convert the compounds into solids of the desired form. Transport and storage of NR latex feedstock is stabilized with chemical agents (e.g., ammonia such ammonia hydroxide) before transporting the latex to the rubber goods manufacturing facility or storage site. Adding ammonium is a pre-vulcanization step and to the extent possible, pre-vulcanization methods and treatments will be limited as prevulcanization treatments can have deleterious effects on the aged and un-aged physical properties of latex fiber/filaments.
[00144] The embodiments of the invention include that the natural rubber source material retains and maintains their optimal stability throughout the rubber fib er/fil ament production process. Poor practices during addition of materials or compounding can result in destabilization and/or poor homogeneity, which may cause downstream difficulties with processing or undesirable characteristics in the finished product. For example, to ensure colloidal stability the emulsion should be agitated gently with a mixer before and during addition of any ingredients. Agitation should be sufficient to produce good turnover at sufficient shear, or low shear, and without introducing excessive or large air bubbles, for example, such as that introduced when suspensions are vortexed.
[00145] To prevent films from forming at the surface or top layer of any NRL or PENRL emulsion or emulsion compound that are stored in big, open storage containers, mixing vessels, production tanks, bioreactors, or the like, should be agitated gently to keep the emulsion mixing at some low shear rate.
[00146] Maintain the amount or volume of compounding may be forty to fifty (40- 50) gallons as when trials are being performed up to several thousand (1,000+) gallons for a production run. No limits to the amount or volume of compounded latex are suggested as it depends on the equipment capacity, manufacturing capacity and need.
[00147] Remove ammonia or ammonium hydroxide from the NRL or PENRL source material before further compounding it. Standard methods for removing ammonia are well known in the art, but as it relates to PENRL, proper care and treatment of the PENRL emulsion is critical to ensure material quality and processability in subsequent steps and PENRL should be stored in storage containers should that remain sealed until time of use.
[00148] Maintain a NR or NRL that is heat labile or can withstand high temperatures while still maintaining its high-performance physical properties as described for PENR herein and in Example 2. Super heat resistant fiber/filaments made from PENR should retain at least 80% of the modulus after exposure to dry heat of 150C for about 2 hours while non-PENR fiber/filaments would be expected to retain only about 50% modulus. For example, the latex should be heated to a specific temperature to stabilize and activate ingredients necessary to produce fiber/filaments of desired physical performance and visual appearance. The storage temperature may range from 20C to 125C. The compounded latex may be controlled at a lower temperature ranging between 5C and 15C. The compounded latex may be warmed to production temperature prior to transfer and production as noted above.
[00149] Addition of any chemical agents or materials should have a pH as close to the emulsion as possible. All agents or materials should be added slowly to avoid again introducing air bubbles and reduce the risk of “shocking” the emulsion, which can induce local to widespread coagulation.
[00150] Maintain a proper emulsion and to prevent agglomeration, many of the agents or materials including but not limited to sulfur, accelerators, activators, and antioxidants that are added should be thoroughly mixed and allowed to evenly redisperse into solution, preferably filtered, before they are added to the NRL suspension or emulsion. These dispersion form typically between 30 and 60% solids and will settle over time and therefore evenly redispersing them in solution is preferred. Checking the total solids content versus the value on the dispersion Certificate of Analysis (CoA) can be a good way to confirm adequate dispersion if in question.
[00151] Filter NRL prior to use to remove any large particulates or coagulum that may have built up during mixing. This will help ensure a material of good consistency and help to reduce potential defects on subsequent, downstream, parts. In one embodiment, an easy means of filtering the NRL or PENRL compound is filtering it through 2-4 layers of cheesecloth or similar compatible materials (nylon, PE, PP) of adequate mesh size is recommended. Use of basket type filtration systems work well for bulk filtration.
[00152] Add agents, chemicals, ingredients and/or materials in a certain order for example any of the below alone or in combination: 1) unpurified (or regular NRL) and PENRL Latex; 2) KOH or ammonia (pH modifiers); 3) Surfactants/stabilizers; 4) Accelerators; 5) Antioxidants; 6) Sulfur; 7) Activator; 8) Fillers, pigments; and/or 9) Additional water for viscosity/total solids adjustment [00153] Advantageous to add pH modifiers and stabilizers and then allow a period for these to equilibrate with the rubber particles in the emulsion. During this period, the stabilizers can interact fully with the surface of the rubber particles before additional compounding steps.
[00154] After all the chemical ingredients are added to the NRL or PENRL source material the compounded suspension will experience gradual changes during what is referred to as the maturation period or pot-life, which includes the storage conditions. The time the compounded emulsion is in storage as well as the storage conditions will impact this maturation and the final physical properties of the rubber product made there from, including rubber fiber/filament. During this maturation period the different materials mixed to form the compound will have the opportunity to interact and equilibrate. During this period cross-linking will slowly but steadily take place, particularly with the use of modern ultra-accelerators. This change in the compound can be observed in the gradual increase of the viscosity as tested using e.g., the Swollen Diameter or Chloroform Number tests. If the NRL or PENRL compound emulsion is allowed to store too long or under poor conditions, the result will be product with poor physical properties.
[00155] The above ingredients are combined (“compounding” or “compounded”) and cured for about 30 min. at about 120°C. Drying & curing in hot air is often combined as described above. Modifying the time and temperature of any curing or drying is well within the skill of one in the art depending on the equipment used and testing parameters and end-use application. Such modifications are not a deviation from the invention herein.
Sulfur to accelerator ratios
[00156] Determining the Sulfur to accelerator ratio will depend on the application and physical property desired of the product, but about 0.75 to about 2.50 PHR. Altering the sulfur cure has an impact on the crosslink density by shifting the ratio of sulfur to accelerators.
[00157] Embodiments herein include those where the sulfur is high at 2.0PHR to 6.0PHR and accelerators being low at 0.2PHR to 0.50PHR; a semi efficient method, where the sulfur is mid-point at 1.50PHR to 3.0PHR and accelerators at 1.0PHR to 2.75PHR; the Sulfur is low but still efficient at l.OPHR to 0.50PHR and accelerators at 1.25PHR to 4.0PHR; or multiple combinations thereof with a shift towards lowering or increasing sulfur to accelerator ratio. Crosslink density alters as this ratio alters creating polysulfidic, disulfidic and mono sulfidic links. Accelerated sulfur vulcanizations are classified as conventional (CV, A/S = 0.1 0.7), semi -efficient (SEV, A/S = 0.7 2.5), and efficient (EV, A/S = 2.5 12), depending on the accelerator/ sulfur (A/S) ratio, with the amount of both components being given in phr. See Table 4.
Table 4: Sulfur to Accelerator Ratio
Figure imgf000031_0001
[00158] There are common rubber curing accelerators available on the market and the invention herein is not limited to which accelerator is used.
Fillers
[00159] Inorganic fillers are added to reduce cost and increase stiffness of the fib er/fil ament while influencing flow behavior of the compound. The typical reinforcement effects of fillers as observed in dry rubber compounds are not observed in latex compounds. For example, carbon blacks or fine particle size clays do not enhance the tensile strength or tear strength since there is no mastication step involved in latex compounds and thus no free radicals are needed to interact with reactive sites on the fillers.
[00160] Clays (soft and/or hard) of fine particle size are used in the form of dispersion in water. It is necessary to check the pH of aqueous clay slurries is 7.0 - 8.0. Any acidity may be corrected by addition of dilute KOH solution. Clay loadings from 30 - 100 phr produce soft vulcanizates with higher tension set.
[00161] Calcium carbonates (white, chalks etc.) give poor quality products with marked tendency to discoloration. The water-soluble salts in calcium carbonates (e.g., chlorides, sulphate s etc.) tend to reduce latex stability. To avoid this small amount of sodium carbonate is added to the whiting slurry prior to addition to latex to ensure that the pH is alkaline.
[00162] Rutile titanium dioxide - white inorganic pigment in latex compound.
Anatase can also be used. Usually, 5 phr is used on dry basis and incorporated as 50% or 30% dispersion slurry.
[00163] White pigments are used to impart whiteness and to provide white background for pastel shades. Blanc fixe (Ppt. Barium Sulphate) filler is used to get smooth and strong deposits of white color on the products. However, it causes loss of extensibility, elongation, and sedimentation.
[00164] Carbon black is sometimes used as a black pigment; however, other pigments are commercially available and widely used depending on the product and application.
[00165] Organic fillers like high styrene resins enhance the stiffness and strength of the deposits based on latex compounds. There is a progressive increase in the modulus values of latex compounds without much loss in elongation at break when high styrene resins are used. These resin lattices are available for blending with NR latex and the proportions used are in the range of 10 - 25 phr.
[00166] Persons skilled in the art will readily appreciate that various aspects of the present disclosure can be realized by any number of methods and apparatus configured to perform the intended functions.
Natural Rubber & Purified natural rubber formulations (70-85%)
[00167] Various embodiments or formulations are described, and depending on the application, including natural rubber fibres comprise of about 80% or more natural rubber (e.g. 80%, 81%, 82%, 83%, 84%, 85%, 86%, 90% or more) and natural rubbers filaments with less than 80% natural rubber content (e.g., 50%, 55%„ 60%, 65%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78% or less), which can be accomplished by the addition of fillers, e.g. white fillers such as Dixie Clay, kaolin clays and/or calcium carbonate or equivalents now known or later developed.
[00168] White fillers are mineral based elements that can be from a class of filler systems used extensively in the rubber compounding industry and include: kaolin, silica, titanium dioxide, calcium carbonate, zinc oxide and talcs and may be organic or inorganic depending on their carbon structure.
[00169] Both kaolin clay (AKA, Dixie Clay) and calcium carbonate are used in latex compounding to impart physical properties and/or to reduce the cost of the compound by “filling” the formula in and reducing the amount and therefore cost of using latex rubber alone. White fillers of all types have a steep benefit to physical properties impact in that lower percentages have little effect on elongation, tensile strength, tear strength and modulus (stiffness) up to a point and then decline very rapidly. See FIG. 20.
[00170] As the percentage or parts by weight increases there is a gain in some physical properties over that of no filler and is dependent upon the size of the filler particles. Particle size and type of filler has little effect on the tensile strength of the fib er/fil ament and is there mainly to dilute the percentage of rubber. Some white fillers do act as strengthening agents as do certain carbon blacks. This is based on the interaction at the molecular level between the rubber molecule and the filler.
However, white fillers will increase stiffness or modulus even at lower loading levels. The interaction between white fillers and sulfur curing agent loading or parts by weight (PHR, or percentage) is just as impactful as the type and amount of filler. Trials will need to be run to determine if the sulfur dispersion needs to be reduced as a function of physical properties. In addition, certain white fillers will fall towards the base pH scale white others may fall towards the acid pH scale and will be noted on their respective TDS or MSDS, so it is very important during compounding to monitor pH and make the necessary adjustments with ammonia (KOH), water or other pH adjustment agent. Always add dispersions slowly to avoid compound shock.
Kaolin Clays
[00171] We have identified Kaolinite mineral clay as the best white filler for the filament project to modify the percentage of natural rubber content in the formulas and hence finished product. The brand name Dixie Clay (Akron Dispersions) is a high-quality kaolin clay dispersion and is both frequently used in latex formulations and distributed by Emersive in Malaysia (emersive.com) across Asia with distribution hubs in Vietnam and Thailand. Kaolinite is a clay mineral, with the chemical composition A12Si2Os(OH)4. It is an important industrial mineral. It is a layered silicate mineral, with one tetrahedral sheet of silica linked through oxygen atoms to one octahedral sheet of alumina octahedra.
[00172] The Dixie Clay dispersion is produced by adding finely milled kaolin clay into an attrition mill where water and soaps are added to produce a slurry of 45-60% solids content and milled for 48 hours to finely reduce the clay particle size. After milling the mixture is filtered, pH adjusted, and an antimicrobial added for protection and storage. The mixture is packaged and shipped. Upon arrival at the facility of use, the material is thoroughly mixed and stirred to blend all material that may have settled at the bottom of the container. Once mixed, the material is measured out for use through a filter of appropriate mesh size to remove any large agglomerates and chunks.
Methods for spinning yarns incorporating Natural Rubber & Purified Natural Rubber filaments
[00173] Once the natural rubber filament is produced, there are different spinning methods available to make the many yarns as described herein, including ring-spun, rotor-spun, twistless, wrap-spun, core-spun or dual core-spun, and air-jet spun yarns as described above and generally known to one of ordinary skill in the art. Yarns described herein are made generally of a few steps: 1) “Mixing” refers to the bringing together of more than one variety of the same basic fibre (e.g., Egyptian cotton fibre combined with American cotton fibre) making the final yam still 100% cotton; 2) “Blending” refers to the bringing together of fibres of different types (e.g. wool and silk or cotton and polyester fibres; 3) Cleaning and fibre separation to remove impurities from raw fibres and some are washed or scoured, while others are combed or carded to further separate and clean the fibres; 4) Fibre alignment or drawing refers to groups slivers or groups of carded or combed fibres and attenuated to form a single sliver of straightened fibres; 5) Drafting and twisting. Drafting refers to gently stretching out the slivers to reduce their linear density or thickness. The exact method and machinery used will depend upon the required yarn quality and count. In the final process, the required amount of twist is inserted into the single yam. [00174] Figures 18-29 are adopted from Sinclair, R. (Ed.). (2014). Textiles and fashion : Materials, Design and Technology, Elsevier Science & Technology, Chapter 8, which is incorporated by reference in its entirety.
[00175] Figure 18 describes the count range for the different end-uses of staplefibre yams from fine yarn count of 2-7.5 tex meant for hosiery, staple-fibre yarns have almost similar market areas, where fine to medium yam counts of 7.5-40 tex are used to make textiles for clothing and apparel. Spun staple yarns hold a major position in the market for items such as shirts, blouses, denim, athleisure wear, sportswear, and countless apparel and home textiles.
[00176] Figure 19 is a drawing describing a ring (conventional) spinning, a process that spins the short, raw fibre into a continuous yarn using a series of machines developed for cotton and wool: opening, carding, drawing, combing, roving, and spinning.
[00177] Opening: Opening is the process of reducing compressed cotton fibres from a bale into smaller-fibre tufts. It removes the particles of dirt, dust, and other impurities by using spiked rollers.
[00178] Carding: After blending and opening, loose fibres are transferred to a carding machine. Carding is performed by opposing sets of teeth or small wire hooks known as card clothing, which cover the machine parts and include a licker-in, a cylinder, revolving flats, and a doffer. The cylinder and the flats may rotate in the same or opposing directions but at different speeds to tease the fibre tufts into a thin, filmy web, which is then collected into a loose rope-like structure called a sliver, which is often coiled, and deposited in cans. The drawing frame uses a series of rollers arranged in pairs and rotating at different speeds. The fibres will be well parallelized and mixed after going through this process.
[00179] Combing: Combing is the process used to remove short fibres and neps (knot or tangle) from sheets of cotton fibres (lap). A roller with fine-toothed elements fixed on a half-lap is used. The amount and length of the short fibres extracted will depend on the combing parameters selected. The fibres will be straightened and paralleled during this process.
[00180] Roving: In this process, slivers are reduced to around one-eighth of their original diameter by three pairs of rollers, rotating at different speeds. The required level of twist is also imparted to keep the rovings stable under the stretching caused by winding and unwinding.
[00181] Ring spinning: The conversion of roving into yarn is called the spinning process. This is usually done in a roller drafting system that will have some means of fibre control, such as a double apron. Twist is imparted to the fibre strands to prevent slippage through the ring and traveler. The yam is then wound onto suitable bobbins known as ring cops for further processing.
[00182] Figure 20 are images of uncovered natural rubber filaments made by the spinning processes described herein including but not limited to ring-spinning.
[00183] Figure 21 describes a process of hollow spindle spinning method. Hollow spindle spinning replaces the twist in a yarn by wrapping a filament binder around the materials used. This results in a fasciated yarn structure in which most of the core fibres/yams run parallel to one another along the axis of the strand, while the binder imparts the necessary cohesion. Despite superficial similarities, yarns made using the hollow-spindle system are quite different in structure from those made by the conventional ring-spinning system. They are also likely to differ in details of appearance and behavior during processing. Hollow-spindle yarns are used in knitted garments or fabrics, although plain yarns have found many other applications such as carpets and medical textiles.
[00184] Figure 21 shows four independent feeding devices, three for effect fibres and one for the core yarn. The effect fibres are fed in the form of staple roving or slivers. The fibres are then drafted using a roller drafting system like that used on ring frames. The effect fibres are combined with the core yarns and then passed through the rotating hollow spindle. A bobbin bearing the binder, usually a filament yam, is mounted on the hollow spindle and rotates with it. The binder yarn is pulled into the hollow spindle from the top. The rotation of the hollow spindle wraps the binder around the staple strand and the core yarns. The binder then holds the effect and core yarns in place. To avoid the possibility of the drafted staple strand disintegrating before it is wrapped by the binder, the spindle usually generates a false twist in the staple strand. The staple strand does not therefore pass directly through the hollow spindle but is first wrapped around a twist regulator, which is usually placed at the bottom of the spindle. [00185] Figures 22 and 23 are drawings combining the benefits of the ring and hollow-spindle systems in a single machine, as it was thought that a yam with twist had a more stable and reliable structure than one with a fasciated structure. Later, it was recognized that two hollow spindles could also be assembled in series and that this would offer a variety of yarns and a different range of benefits. Figure 22 shows two hollow spindles arranged one above the other, which wrap the staple strand with two binders applied in opposing directions. This technique is used to produce specialeffect yarns that have a more stable structure, as the effect fibres are trapped by two binders instead of one.
[00186] Figure 23 is a drawing showing a combined system in which the hollow spindle and ring spindle are combined in a single machine. The wrapped yam is provided with some true twist by the ring spindle placed immediately below the hollow spindle.
[00187] The conventional doubling system is also based on ring spinning. The arrangement provides two or more yarns that can be fed independently at controlled speeds. These may include uniform, fluctuating or intermittent feeds as required, so permitting a simple means of producing spiral or marl-type yarns, although obviously requiring the feed material to be in yarn form.
[00188] Another method for making yarns using an open-ended spinning principle is rotor and friction spinning. Figure 24 is drawing showing a typical rotor system that can be used to produce coarse to medium count short staple yarns; whereas the friction system is used to make coarser industrial yams and either can be used for making some fancy yarns.
[00189] Figure 24 shows a rotor system where the yarn twisting action is separated from the winding action and the package needs to rotate only at a low winding speed. The process may be divided into the following steps: opening, transport, alignment, and overlapping and twist insertion. Individual fibres are carried into the rotor on an air stream and laid in contact with the collecting surface so that a strand of fibres is assembled around the circumference. As the fibres are drawn off, twist is imparted by the rotor, to produce a yam. Rotor spinning is most suitable for spinning short staplefibre yams. Modem, computerized, and automated rotor spinning machines can make slub yarns. These yarns are used in furnishings and drapes, rather than in apparel fabrics, and sometimes used in denim fabrics. They are manufactured using attachments to ordinary open-end spinning devices, which usually incorporate an electronically controlled device for the brief acceleration of the drawing-in roller. As a result of the back doubling action inside the rotor, it is not possible to produce slubs shorter than the circumference length of the rotor because any variation in the fibre feed material is spread over a minimum length of the rotor circumference.
[00190] Figure 25 is a diagram showing an open-ended spinning method called friction system (a DREF-2 machine). Instead of using a rotor, two friction rollers are used to collect the opened-up fibres and to twist them into yam. The fibres are fed in sliver form and are opened by the opening roller. The opened fibres are then blown off the opening roller by an air current and transported to the nip area of two perforated friction drums. The fibres are drawn onto the surfaces of the friction drums by air suction. The two friction drums rotate in the same direction, and twist is imparted to the fibre strands because of the friction with the two drum surfaces. The yarn is withdrawn in the direction parallel to the axis of the friction drums and is delivered to a package-forming unit. A high twisting speed can be obtained even while using a low speed for the friction drums, because the friction drum diameter is much larger than that of the yam.
[00191] Figure 26 describes another type of open-ended spinning called vortex spinning to make fasciated yarn technologies. The Murata Vortex spinning (MVS) for example can spin carded cotton yarns at speeds significantly higher than any other system currently in existence. The machine produces yarn at 400 m/min, which is almost 20 times that of ring-spinning frame production.
[00192] Figure 27 is a diagram showing yet another method of spinning yarns called air-jet spinning, which is a pneumatic method and is not an open-end spinning process. The drafted fibre strands pass through one or two air nozzles located between the front drafting roller and the take-up system. The roller drafting system drafts the input sliver into a ribbon-like parallel fibre strand. High-pressure air is injected into the nozzles, causing swirling airstreams inside the nozzle. This results in the insertion of false twists into the drafted fibre strands. The edge fibres wrap onto the surface of core strand and form the yarn. [00193] Figure 28 shows yet another method for spinning yarns, specifically chenille type yarns that form two ends at each unit. The effect yarns are wrapped around a gauge or former which is triangularly shaped at the top, narrowing towards the base to allow the effect yam coils to slide downwards onto the cutting knife. The width at the bottom of the gauge determines the effect length, by maintaining the depth of the pile, or ‘beard,’ in the final yam. Although, for the sake of simplicity, the cutting knife is shown in Figure 8.31 as a straight knife edge, modem machines all use a circular cutting knife. On each side of the cutting knife there are two ground yarns, which may be either single or twofold. One ground yarn is guided by the takeup roller while the other is guided by the companion roller. The take-up roller is pressed against the profiled guide and inter-meshes with the companion roller, allowing the two ground yams to trap the pile created by the effect yarn in between them at right angles to the ground yarn axis. The two ground yarns are twisted together, usually by a ring spindle at the lower part of the machine, to produce the final yarn. Chenille effects can also be manufactured by a flocking process in which a ground yarn coated with adhesive is flocked electrostatically with loose fibres.
[00194] Different types of yarns from staple fibres and continuous filaments from both natural and synthetic materials are described herein in terms of their structures, properties and applications and general methodologies.
[00195] In the case of synthetic continuous-filament yams, manufacturing methods including melt spinning, wet spinning, dry spinning, and gel spinning techniques are explained and different forms of continuous- filament yams are dealt with, such as flat yarns, textured yams, bi-component yarns and split tape or film yarns. In case of staple-fibre yarns, manufacturing technologies including ring, rotor, air-jet spinning, and Vortex spinning are explained together with the type of yarn structures obtained from the respective technologies and their end-uses.
[00196] One skilled in the art can modify any of the methodologies described herein for their own purpose and customize it according to application (apparel e.g.) and the fibres (natural and/or synthetic) used to cover the PENR fibre for example. Appropriate yarn structures and manufacturing technologies are selected for required applications and properties. Methods for weaving fabrics from yams made with Natural Rubber & Purified Natural Rubber filaments
[00197] Weaving is the interlacement of two sets of fiber/filaments: the warp fib er/fil aments that run vertically through the length of the fabric and weft fiber/filaments that run horizontally across the width of the cloth on a loom. There are different types of looms (table loom, rigid heddle loom, floor/treadle loom, counterbalanced loom, dobby loom, computerized loom (e.g. APSO, AVL and Scotweave), jacquard loom, shuttleless loom, and triaxial loom), but they have the same basic function, which is to hold the warp yarns taut and under tension, whilst weft yarns are inserted and beaten into place to form the fabric.
[00198] The basic features common to all types of looms are: Frame: Secures components; Beam: Secures and stores the warp and is at the back of the loom. Some looms have more than one beam. If the loom has more than one back beam, it can be used for weaving two different types of warps for double cloth or warps at different tensions. The cloth beam at the front stores finished weaving. The width of each beam determines the extent of the width of the cloth. Shafts: Consist of an upper and lower bar carrying the heddles. They control the rise and fall of the warp fiber/filaments, thus forming the shed (there can be as few as 2 shafts or as many as 16 shafts on a table loom, or as many as 24 shafts on a floor loom). Heddles: Rest on the shafts of the loom. The warp yarns are threaded through the eye of the heddles. Batten: Pivoted frame holding the reed. It can hang from the top of the loom (overslung) or be pivoted at floor level (underslung). Reed: Used for spacing the warp and beating the weft. It can vary in size and ideally it should be made of stainless steel to prevent rusting. Levers (table loom) or peddles (floor loom): Raise and lower the shafts. Levers are placed at one or both sides of the frame. Peddles may be pivoted from the front or back.
[00199] Traditional yams used for warp threads in tapestry weaving are wool, silk, linen, and cotton, but many use only cotton for the warp threads, due to its strength and its tendency not to stretch. Warp yarns do not need to be dyed prior to weaving as they will be covered completely by the weft yarns. Methods for knitting fabrics from yarns made with Natural Rubber & Purified Natural
Rubber filaments
[00200] Knitting is producing a textile fabric from a series of intermeshing loops. Different methodologies exist, most modem knitwear is produced using sophisticated computer-controlled machinery (weft knitting), which is derived from either hand or pin or needle knitting, which involves two large needles or pins and a single end of yarn. There are 2 principal types of knitting: weft knitting and warp knitting.
[00201] Knitted fabrics vary significantly in weight, from ultra-lightweight (termed fine gauge) used in sporting and underwear applications, to heavier structures used in outerwear sweaters (termed chunky gauge). The term “gauge” refers to the fineness of the fabric, although it actually refers to the number of needles (per inch) within the needle bed (although there are notable exceptions: in some older weft-knitting machinery the gauge is expressed as number of needles per 1.5 inches, and in raschel warp knitting machines it is number of needles per 2 inches). But in general terms, 18-, 14-, 12- and 10-gauge machines produce lightweight fabrics; midweight fabrics are produced on 8 or 7 gauge; and 5, 3 and 2.5 gauges produce heavyweight fabrics. There are two distinct types of knitting technologies that produce vastly different fabrics for specific applications (weft and warp).
[00202] Most knitted garments available are constructed from weft-knitted fabrics. This is by far the most versatile method of knitting, as the technology allows for a variety of structures to be produced that can combine extensive patterning in the form of texture and color. Weft-knitted fabrics are flexible and will extend in all directions, have good elastic recovery, superb formability, and drape, provide excellent thermal insulation and are resistant to creases. However, they suffer from poor shape retention, are prone to pilling and ladder easily. In contrast warp knitted structures are more stable but lack drape properties. Warp knitted structures are produced using multiple yarn ends and the loops intermesh diagonally with the adjacent vertical columns. The resultant fabrics are ladder resistant and find end-uses in a variety of areas including, lace, openwork, net, underwear, sportswear, and technical applications.
[00203] There are 4 types of weft-knitting machinery: circular, fully fashioned and flatbed and that which produce seamless garments. The most productive method of manufacturing weft-knitted fabrics is utilizing the circular knitting machine. In this method, the knitting needles are arranged in a circular formation and can be fed from a variety of sources located around the circumference of the machine; hence more than one course is knitted in a single revolution. The fabrics obtained from this machine are continuous tubes that can be slit to produce an open width fabric. Single- and double-jersey fabrics utilized in T-shirts and sweatshirts are manufactured using this technology. One example of recent advances in circular technology includes seamless Santoni technology. Santoni has produced small diameter machines that produce a tube of fabric to fit over the body contour. It is seamless in the sense that it has no side seams, but this machinery should not be confused with the flatbed complete garment process that can produce truly seamless garments (hence, a body with two integral sleeves). Traditionally, high-class knitwear was produced on a special class of machinery termed the straight bar frame (or Cottons Patent Machines as they are more commonly referred to). The advantage of this machinery is that it can shape individual panels (front, back and sleeves). Traditionally, shaping was seen as essential for garments constructed from luxury yarns (cashmere, merino wool, lamb’s wool, and others) that were too expensive to produce using cut and sew manufacturing.
[00204] The modern flatbed machines are the most versatile of all weft-knitting technology. They can produce ribs combined with complex structures, different patterning options, panel shaping and integral knitting (knitting pockets, collars, and trims into the garment). The only disadvantage is speed, but this has improved significantly in recent years (the latest technology operates at 1.6 m/s). Most fashion knitwear (excluding T-shirts) on the high street is produced using flatbed machinery. There are two major players in this area of innovation: the German company Stoll, with its Knit & Wear range of machinery, and the Japanese company Shima Seiki with its Whole garment machinery range. These machines are designed to produce a complete garment; hence, the entire sweater or other garment produced by one of these machines is seamless and there are no post knitting operations to be completed after knitting (except for labelling and sewing in the ends of yarn).
[00205] Warp knitted structures are constructed from intertwined loops, with the yarns that connect them crossing in a zigzag formation. A warp knitting machine consists of needles extending across the width of the machine like a weft machine, but each individual needle is fed from an independent yarn source. Hence, each needle is fed by its own yarn supply delivered by a guide that directs the yarn around the needle during the knitting action. It should be noted that all the wales in one course (i.e., vertical column) are formed simultaneously. The yams that feed through the guide bars are wrapped onto a warp beam (like the weaving process); a machine could consist of two to four beams depending on the fabric type to be obtained. The difference in the orientation of the yarn, fed from the weft to the warp direction, enables vastly different structures to be produced at extremely high speeds. Warp knitted fabrics produced are continuous sheets of materials and usually produced from filament yarns which can be utilized in a variety of applications from industrial to fashion garments. The varieties of fabrics that can be produced are among the widest ranges of any textile manufacturing method. There is a wide range of machinery available in a variety of widths from small crochet and scarf making machines, to gigantic machinery (5 m wide) used to produce industrial fabrics. Whilst both warp and weft technologies are referred to as knitting, the fabrics produced are so vastly different.
[00206] Tricot and raschel warp are 2 types of knitting machines. The structures obtained from the tricot machine are of the plain type and find many applications, particularly in lingerie and Sportswear; quite often, these incorporate elastane or Lycra to produce fabrics with two-way stretch.
[00207] Raschel machines can knit yams in both filament and staple form into open works, laces, jacquards, fancywork (largest outlet) and pile fabrics. Structures produced from the raschel machine do not tend to stretch significantly and can be designed to be highly structural for technical applications.
[00208] Shima Seiki’s most recent machine range is the Mach 2X and Mach 2S, which claims significantly higher productivity than earlier versions of whole garment and is programmed through the SDS-ONE APEX design software. Various models of Stoll’s CMS Knit & Wear machinery are available, and programmable using Ml Plus software. The advantages of producing using complete garment technology are elimination of waste, reduced labor (compared to other methods) and comfort (due to having no seams) in close-to-body-fitting garments. [00209] The most common warp knitted structures in clothing and Fashion are those produced using the tricot type of machine. The most common warp knitted structures to be produced are those of the plain tricot type knitted with two needle bars. However, in fashion applications locknit is by far the most popular option since it has good extensibility, cover, handle, and excellent drape, and is flatter on the reverse of the fabric. In contrast, raschel machines can have one or two beds of needles (hence they can produce double structures). Many fabric types can be produced but the general structure categories can be divided into five types: openwork, inlaid yarns, double structures, pile structures and structures with spacers. The structures used in clothing applications tend to be split into three categories: those used in functional clothing such as bi-directional stretch fabrics; the supportive component in laminate structures and compression fabrics; and those which add aesthetic value such as laces, jacquards, and fancy nets. The Italian design house Missoni continues to produce sophisticated warp knitwear designs, and Karl Mayer, the German warp knitting manufacturer, remains a global leader in the development of warp knitting machines.
[00210] The latest flatbed weft-knitting technology, or the complete garment technology, should not be confused with circular technology that is described as seamless. The former produces a garment in its entirety, whereas the latter produces a seamless tube (gussets, sleeves and straps need to be attached by auxiliary machinery).
[00211] Computers have had a large effect and sea change in design and technology in knitting. Shima Seiki’s Mach 2X and Mach 2S, have higher productivity than earlier versions of whole garment, and is programmed through the SDS-ONE APEX design software. Various models of Stoll’s CMS Knit & Wear machinery are available, and programmable using Ml Plus software. The advantages of producing using complete garment technology are elimination of waste, reduced labor (compared to other methods) and comfort (due to having no seams) in close-to- body-fitting garments. Further opportunities in CAD/CAM and 3D graphics are paving the way for innovation and efficiency. Hence, the advent of computer technology, in terms of hardware and software development, will continue to impact on design innovation of knitted products. Hence, the application and use of yams comprising PENR fibres for knitting (weft or warp) is limitless - from socks to whole-body garments.
Methods for producing nonwoven fabrics from yarns made with natural rubber and purified natural rubber filaments
[00212] Typically, not considered a fabric made from yarn per se but a nonwoven fabric is a sheet of fibres, continuous filaments or chopped yarns of any nature or origin, which have been formed into a web by any means, and bonded together by any means, except for weaving or knitting. A nonwoven fabric structure is different from some other textile structures in the following aspects: i) It principally consists of individual fibres or layers of fibrous webs rather than yarns; ii) It is anisotropic both in terms of its structure and properties due to both fibre alignment (i.e. the fibre orientation distribution) and the arrangement of the bonding points in its structure.; iii) It is usually not completely uniform in fabric weight, fabric thickness or both; and iv) It is highly porous and permeable. Hence, it is possible that non-woven fabrics have yams made of PENR fibres all the same.
Methods for producing intelligent fabrics from yams made with natural rubber and purified natural rubber filaments
[00213] There is a constant innovation for intelligent fabrics, or intelligent or smart textiles, including wearable technology, consisting often of a sensor, a processor, and an actuator, all managed by controlling data. For example, body temperature monitored by the sensor is transferred to a processor, which computes a solution based on the received information and sends a command to the actuator for temperature regulation. This is a theoretical definition - an example of an intelligent textile system in practice is a jacket made using Outlast, a thermoregulating phase change fabric. When a wearer’s body temperature rises above a certain point, the fabric cools the body by absorbing excess heat. At times when the temperature decreases below the threshold point, heat is returned, and the wearer feels warmer. Hence, yams and fabrics incorporating PENR fibres can be utilized in smart fabrics.
Methods for testing biodegradability
[00214] A holistic view of sustainability focuses not only on manufacturing and safety, but also on the end of the product life cycle and its impact. If it is not reused, recycled, upcycled, or repurposed in some way, textiles often end up in a landfill or compost. Biodegradable textile products should ideally degrade completely in the soil and residues or degradation products from dyeing or finishing processes should have no negative impact on the environment.
[00215] Biodegradation product testing, when intended for product claims related to biodegradability, should incorporate several factors of the product’s actual performance, or intended use. For example, products can be tested for ‘Ready Biodegradability’ under OECD 301B biodegradation test method. OECD 302B is an inherent aerobic biodegradation test used for determining the biodegradability of a solution typically not readily biodegradable, is known to be insoluble or does not satisfy the requirements of OECD 301. Biodegradation testing for plastics is typically run in conditions approximating commercial composting; biodegradation tests for liquids are run in representative aquatic systems. For example, plastic disintegration is typically under ISO 16929 and OECD 30 IB for liquid biodegradation.
[00216] Claims should be made specific to the test methods and to the product or component part. Biodegradability is directed to the product, whether finished goods or components, it does not speak to the method of making the product/component. Because finished goods or products are combinations of several materials or formulation components, the reliance on any one component biodegradability can be misleading when used as the assessment for the entire finished product. It would depend on how much of any one component makes up the finished good. Product development should ideally require product testing of the formulation components and variants of material construction.
[00217] Biodegradability testing measures the complex biochemical process that occurs when microorganisms consume a given type of material. And although complicated, the test results measure simple markers of the biodegradation process. Some regulations require biodegradability claims to be based on aerobic biodegradation, which typically measures oxygen consumption, CO2 production and the state of inorganic carbon intermediates.
[00218] Challenges with biodegradation testing include the complexity of the biochemical interactions, the composition of the materials tested, and the specific needs of each biodegradation test. Materials that are made up of components known to biodegrade sometimes do not ‘pass,’ and materials made of inorganic components do not necessarily ‘fail’ the various assessments of biodegradability.
Denim fabrics from fine natural fibres/filaments
[00219] Typical properties of denim are cotton or cotton-polyester blend, durable light to heavy weight twill weave, and yarn-dyed fabric. Other features include: i) colored warp and white weft; ii) left-hand twill with a blue (indigo) warp white weft; iii) warp-faced twill; iv) available in 203.46 gm/m2 (6 oz/yd2) to 474.74 gm/m2 (14 6 oz/yd2) or more in a 2/1 or 3/1 interlacing pattern; v) napped, printed, made with spandex or other stretch yarns, or modified for fashion.
[00220] The yarns for denim also have typical features including: i) minimum staple length: 2.7 cm; ii) proportion of short fibres (less than 12 mm long): iii) under 40%: Micronaire value: 4.0 to 4.5; iv) count range of denim warp yams is 50 to 90 tex and weft yams is 75 to 120 tex; finer yarns as fine as 25 tex in twill or plain weave are used in denim shirts.
[00221] Denim is measured by how many ounces are in a square yard of fabric. Usually lightweight denim is 5-12 ounces (oz), mid-weight is 12-16oz, over 16oz is considered heavyweight. Many manufacturers and consumers consider 13-16oz mid- heavy-weight denim. Designers and manufacturers will choose which denim is the most appropriate given the season and type of clothing being made. Lightweight fabric (denim or otherwise) is usually much more supple and flowy. It is often reserved for tops, some skirts, and summer clothing, whereas most jeans, shirts, and jackets are made with 1 l-13oz denim, which is enough heft (or bulk) to make it durable and still comfortable for most weather to make it very wearable. In contrast, heavy-weight denim (or other heavy bulky fabrics) is used for upholstery and occasionally for jeans and jackets. Thus, denim weight matters for comfort and performance, which dictates applications.
[00222] Denim weight is a combination of how thick the yam used to make the fabric is, how tightly woven the yarn is, and how much the yam weighs. If cotton is blended with polyester rather than elastane, there will be a weight differential, as well as having different stretch and durability characteristics. So, 1 loz blended denim will be different depending on what it is combined with. Even if the fabric is all cotton, different looms will weave fabric in different densities or yarn count (mass per unit length). Traditional selvedge jeans are often made on older shuttle looms, especially Japanese selvedge jeans. The denim from these looms is packed in tighter than completely automated bullet looms yet retain its flexibility and softer hand even though they may be of a higher weight. Fabric weight may also dictate the style, especially of jeans. Very heavyweight denim requires a baggier fit because skinny jeans with the same fabric will create skin abrasion and fabric-on-fabric abrasion. Lightweight denim is suitable for skinny jeans, very high-waisted or very wide-legged fashion jeans, where movement is required or necessary.
[00223] How any fabric is processed also determines its performance and feel including laser, prewashed, softened using ozone treatments, or is the cotton blended with other fabrics to highlight a particular characteristic such as elastane (stretchy) or lyocell (flowy).
[00224] Publication W02020084359 (Candiani) describes elastic yarns and fabrics made from the elasticized yarns, in particular stretch denim. However, commercial availability of natural rubber fibers at the time did not allow for a denim of 13 oz or 12 oz or 11 oz or less, which is more desirable; and may be the reason why Candiani required 3 drafts, which is a process of attenuating or stretching the fibers as a way to manipulate the roving (1) during the spinning process as shown in FIG.l of W02020084359. Reasons why finer natural rubber fibres/filaments have not been described to date, include different molecular structure, lower tensile strength, and more complex processing compared to polyurethane spandex fibers. Thus, there has been a long felt need for such fine natural rubber fibers and so it is surprising that Applicants were able to finally make a fine natural rubber fibre/filament with new formulations, purified natural rubber latex with improved properties even with lower tensile strength and modulus compared to spandex. Candiani was not able to predict or suggest that such fine natural rubber filaments were possible prior to Applicants invention.
[00225] Any of the above aspects and embodiments can be combined with any other aspect or embodiment as disclosed here in the Summary, Figures and/or Detailed Description sections. [00226] Unless specifically stated or obvious from context, as used herein, the term “or” is understood to be inclusive and covers both “or” and “and.”
[00227] Unless specifically stated or obvious from context, as used herein, the term “about” is understood as within a range of normal tolerance in the art, for example within 2 standard deviations of the mean.
[00228] The entirety of each patent, patent application, publication and document referenced herein hereby is incorporated by reference. Citation of the above patents, patent applications, publications and documents are not an admission that any of the foregoing is pertinent prior art, nor does it constitute any admission as to the contents or date of these publications or documents. Incorporation by reference of these documents, standing alone, should not be construed as an assertion or admission that any portion of the contents of any document is essential material for satisfying any national or regional statutory disclosure requirement for patent applications.
[00229] Modifications may be made to the foregoing without departing from the basic aspects of the invention. Although the invention has been described in substantial detail with reference to one or more specific embodiments, those of ordinary skill in the art will recognize that changes may be made to the embodiments specifically disclosed in this application, and yet these modifications and improvements are within the scope and spirit of the invention. The invention illustratively described herein suitably may be practiced in the absence of any element(s) not specifically disclosed herein. Thus, for example, in each instance herein any of the terms "comprising", "consisting essentially of', and "consisting of' may be replaced with either of the other two terms.
[00230] Embodiments of the invention are set forth in the following claims.
[00231] The invention will be further described with reference to the examples but understand that the invention is not limited to such examples.
EXAMPLES
EXAMPLE 1 - Exemplary GENERAL METHODS FOR PRODUCTION OF SPANDEX
[00232] Spandex or elastane is a synthetic fibre known for its exceptional elasticity. It is a polyether-polyurea copolymer that was invented in 1958 by chemist Joseph Shivers at DuPont's Benger Laboratory in Waynesboro, Virginia. When introduced in 1962, it revolutionized many areas of the clothing industry. The name "spandex" is an anagram of the word "expands". It is the preferred name in North America; in continental Europe it is referred to by variants of "elastane", i.e. elasthanne (France), Elastan (Germany, Sweden), elastano (Spain), elastam (Italy) and elastaan (Netherlands), and is known in the UK, Ireland, Portugal, Spain, Brazil, Argentina, Australia, New Zealand and Israel primarily as Lycra. Brand names for spandex include Lycra (made by Koch subsidiary Invista, previously a part of DuPont), Elaspan (also Invista), Acepora (Taekwang), Creora (Hyosung), INVIYA (Indorama Corporation), ROICA and Dorlastan (Asahi Kasei), Linel (Fillattice), and ESPA (Toyobo).
[00233] Spandex fibres are produced in four different ways: (i) melt extrusion; (ii) reaction spinning; (iii) solution dry spinning, and (iv) solution wet spinning. All these methods include the initial step of reacting monomers to produce a prepolymer. Once the prepolymer is formed, it is reacted further in various ways and drawn out to make the fibres.
[00234] The solution dry spinning method is used to produce over 94.5% of the world's spandex fibres, and the process has five steps: (1) Produce the prepolymer by mixing a macroglycol with a diisocyanate monomer (1 :2 ratio) in a reaction vessel to produce a prepolymer; (2) React an equal amount of diamine and known as polymer chain extension and then diluted with a solvent (e.g., DMAc) to produce the spinning solution. The solvent helps make the solution thinner and easier to handle, and then it can be pumped into the fibre production cell; (3) The resulting or spinning solution is pumped into a cylindrical spinning cell where it is cured and forced through a metal plate called a spinneret and converted into fibres. This causes the solution to be aligned in strands of liquid polymer. As the strands pass through the cell, they are heated in the presence of a nitrogen and solvent gas, causing the liquid polymer to react chemically and form solid strands; (4) Thickness is achieved by bundling together the fibres as they exit the cell. Each fibre of spandex is made up of many smaller individual fibres that adhere to one another due to the natural stickiness of their surface; and (5) The resulting fibres or bundled fibres are then treated with a finishing agent (e.g. magnesium stearate and the like), which prevents the fibres from sticking together and aids in textile manufacture. The fibres are then transferred through a series of rollers onto a spool.
[00235] Because of its elasticity and strength, (stretching up to five times its length), spandex has been incorporated into a wide range of garments, especially in skin-tight garments. A benefit of spandex is its significant strength and elasticity and its ability to return to the original shape after stretching and faster drying than ordinary fabrics.
[00236] However, spandex and its family of elastic fibres are still commercially made from synthetic polymers and are not bio-based. Hence, there is a still a need to provide a natural rubber fiber/filament and methods of producing a natural rubber fib er/fil ament with equivalent and or improved physical properties to spandex but derived from available natural, bio-based, sources.
[00237] Figures 5 and 6 are general process flow diagram and decision tree, respectively, for use in the present invention.
Example 2 - Physical Properties of Purified Natural Rubber Latex & Testing Methods and Results
[00238] There have been several reasons why a fine natural rubber fibre/filament like spandex has not been described or is commercially available including: i) natural rubber (polyisoprene polymer) has different molecular structure than their petroleum based polyurethane spandex polymers, affecting their ability to spun into fine filaments; ii) natural rubber has relatively lower tensile strength (Mpa) compared to synthetic spandex which again affect its ability to be spun into filaments without breaking or stretching excessively; and iii) different and more stages of processing and refinement are require for a fine natural rubber filament compared to spandex including the steps described above. Thus, surprisingly, the novel compositions and methods for production of fine natural rubber filaments including those made from purified natural rubber latex are the first to describe such.
[00239] A variety of materials tests have been designed and performed to demonstrate the physical, mechanical, environmental, visual, objective and subjective, differences between the purified NRL of the present disclosure purified substantially as described in Steps 1-4 in FIG.2 , compared to crude Hevea (typically purchased as centrifuged or concentrated latex) and a commercially available low protein latex (chemically modified). In addition to comparing these NR latexes, the purification process described herein was also applied to the commercially available “low protein” latex to demonstrate that the method can be utilized and applied to any existing NRL emulsion and improve on this source material. A summary of testing is described in more detail below.
[00240] In addition to the testing methods, the results below for the high- performance natural rubber fibre show that it can be: i) stretched repeatedly and still recover to very near its original length and shape; ii) stretched more than 500% without breaking; iii) having substantially the same retractive force as elastane or spandex; iv) heat-settable; v) dyeable; vi) resistant to deterioration by body oils, perspiration, lotions or detergents; vii) Abrasion resistant; viii) lightweight, soft, smooth, supple; ix) prevents bagging and sagging when incorporated into fabrics and textiles.
Testing Assays
[00241] Tables 1-7 describe the test results from the purified NR using methods described herein (FIG.2). Legend for analyzing these Tables and Figures: Pure NR (purified NR of the present disclosure), Crude (crude Hevea NRL), Centrifuge (crude Hevea NRL centrifuge or concentrated), LP (Hevea Low Protein from Vytex), LP-1 and LP-2 (different lots of Hevea Low Protein from Vytex).
[00242] Total Solids Content (TSC). This tests the capability of the methods of the present invention to process low solids content latex (dilution) to achieve industry standard at 58-63%TSC. Each of the ten (10) lots processed achieved a range of TSC from 59.8% to 64%TSC. TSC is only a test to determine the total amount of solids present in the liquid (latex). See also Table 1, 2 & 3.
[00243] Total percentage of Non-Rubber Content (NRC). This tests the effectiveness of the methods of the present disclosure as compared to commercially available Hevea crude NRL (control) and commercially available low protein NRL to remove non-rubber impurities, remove non-rubber content, organic and inorganic materials including dirt, plant debris, metals and other unwanted materials including proteins, etc... After each lot was processed (n=10), the purified NRL output was tested with a range of 0.01% to 0.09% and an average of 0.05%; for Hevea crude NRL averaged 2.75% (n=10, different lots, IL from each drum was tested); and the Hevea low protein NRL averaged 2.39% (n=4, different lots, IL from each drum was tested). See also Table 1- 3.
[00244] Total Rubber Content (TRC). This tests the effectiveness of the methods of the present disclosure to process and achieve a near Zero delta between TSC and NRC being Total Rubber Content or TRC. That is, TRC is defined as TSC-NRC=TRC or where total solids equals total rubber and non-rubber equals near zero. Alternatively: TSC-TRC=NRC as a percentage (%) (TSC-NRC= TRC). Each of the ten (10) lots was tested for total rubber content prior to the purification process. The average across the ten (10) lost: 62.57% TSC -2.75% NRC= 59.82% TRC. After purification, the purified NRL averaged 61.87 % TSC - 0.06% NRC = 61.82% TRC. See also Table 1- 3.
[00245] Total Protein Content. This tests the capability of the methods of the present disclosure to process and achieve a near Zero delta between test detection at each resolution end.
[00246] Twenty-one (21) lots of commercially available crude Hevea centrifuged NRL were purchased. Each was tested for protein content. Four (4) of the 21 lots purchased were commercially available “Low Protein” NRL (Vytex). Each lot held a retained sample of the latex as received (“received protein”). A total of six (6) liters were retained for testing and comparison purposes. Each lot’s protein was tested and recorded. The lots were then processed using the purification methods described herein. Except for the Low Protein lots, the average total Protein ranged from a max of 1542 ug/g to a low of 459 ug/g. The Low Protein lots averaged 845 ug/g with a high of 1,035 ug/g. Received total protein ranged from a max of 12.465 ug/g to a min of 4,432 ug/g and an average of 7,107ug/g. After each lot was purified per the methods described herein, they averaged 138 ug/g with a low of non-detect (<50 ug/g) to a high of 400 ug/g. The range correlates to a range of dilution wash ratios tested which ranged from 1 : 1 to 17: 1 where the dilution increased to a point that dropped TSC to below 8%. The higher the dilution ratio the greater the total amount of protein removed up to 9/10: 1 where no measurable detection was possible, process periods increased, and total production system loss elevated. See also FIG.9 and Table 1-3.
[00247] Dried Latex Color (air-dried, not coagulated). This tests for the clarity and color of the NRL after purification methods as described herein. Visual comparison was made from 1.5mm to 2.5mm thick cast and air-dried NRL. See FIG. 4A comparing purified, crude, and low protein NRL that were transparent, off-white & yellow, respectively. Visual comparison demonstrated a significant decrease in typical yellow-ish color. All ten (10) lots crude Hevea NRL purchased and purified as described herein showed near transparent clarity over crude Hevea and more significantly of the Hevea Low Protein NRL lots/samples. See also FIG.4.
[00248] Dried Latex Color (coagulated). This tests the color of the coagulated NRL. There was a markedly different coloring between the purified NRL of the present disclosure as compared to both the rib smoked sheet (RSS) solid NR and the baled oven dried NR. See also FIG.4B.
[00249] Uncompounded Green Strength: Tensile. This tests the overall general physical properties after purification methods as described herein as compared to crude NRL. Four (4) different types of commercially available NRL were tested. All the NRL (purified, crude and Low Protein) was put in a cast film and compared against two (2) commercially available centrifuged high ammonia and a low ammonia NRL, and two (2) different lots of Low Protein NRL. Each type was cast with three 1.5mm films, which were air dried after one (1) hour at 60C._Green strength improved after purification of the NRL as described herein and averaged 8.1 from a low of 3.2 Mpa. The feedstock used to produce the purified NRL was baseline and found to produce 3.1 Mpa. See Tables 1- 3.
[00250] Commercial “Low Protein” Latex YPP Production. This test was to demonstrate that chemically decreased latex benefits from the purification methods disclosed herein. Four (4) lots of Low Protein NRL were acquired and were from different production numbers. Each of the latexes was then purified by the methods described herein with different dilution ratios of 9: 1 (PDX-32); 14: 1 (PDX-48); 5: 1 (PDX-17); and_2.5: l (PDX-09). The protein content at the start and after purification was tested and compared. Protein content at the Start: PDX-32: 655; PDX-17: 459; PDX-48: 1,542; and PDX-09:876. Protein content after purification: PDX-32: <50 Non detect; PDX-17: <50 non detect; PDX-48: lOlug/g; and PDX-09: <50 non detect. See -Tables 1- 3.
[00251] Uncompounded and De- Ammoniated Odor. Random samples of six different commercial NRL were taken, deammoniated and tested for odor by five individuals using a blind test. All six samples were air dried as films at 1.5mm thickness and tested again in a blind using same five individuals. Of the six samples taken one was a purified NRL as purified by the present disclosure at 4: 1 ratio. No compounding was used. All six NRL were found to be acceptable in terms of odor being not pungent or offensive. 80% of testers found the purified NRL as being “Without Any Real Odor” compared to the others. The air-dried NRL samples were found to have a robust to acceptable rubber smell where the purified NRL sample was noted by all (100%) as having “No Odor”.
[00252] Uncompounded pH Stability. Designed a test to compare a two-liter sample of four samples of latex, where two (2) were purified NRL as described herein and two were crude Hevea NRL. The test took place at 22C in the lab with pH sensors in each of the samples tested and adjusted to 10.25. The samples were covered with the pH sensors and allowed to sit for a period where the pH dropped below 9.0. This took fourteen (14) days for the crude Hevea NRL to drop below pH 9 as compared to purified NRL that did not drop below pH 9 until after 18 days and one sample not until 21 days. On average the purified NRL maintained pH stability above pH 9 for about 19.5 days and the crude Hevea NRL averaged 12.5 days. The pH of the NRL is a general indicator of bacterial activity. That is, as pH drops there is greater potential for growth of bacteria and mold/yeast. This growth appears flat for several days and then there was a rapid decrease in pH as growth increase logarithmically. Purity of the latex reduces these pH-changing loads and allows for a longer maintenance of pH without the need for additional ammonia, bactericide, or KOH.
[00253] Compounded Strength: Tensile, Elongation & Modulus. Using a master batch compound regarded as an industry standard formula for comparative testing of polymer systems. Improvements across all crude Hevea NRL samples, the purified NRL feedstock served as the baseline. See Tables 1- 3.
[00254] Compounded Strength: Pot Life. This tests the shelf life of the compounded NR before it is used in manufacturing of the rubber product. Pot Life across the purified NRL lots averaged 4.65 weeks as compared to an average of 2.98 weeks for non-purified NRL lots/samples, which decreased at about 12% and then rapidly decreased to 31.6% by mid-week three.
[00255] Uncompounded Mechanical Stability Test (MST). This tests the stability of the latex prior to compounding. Steady state for MST testing compared to crude Hevea NRL samples held for a five (5) week period.
[00256] Coagulum Percentage (%BW). This test is for reduced or comparative levels of coagulum. As per the testing of samples as delivered from the supplier and an appropriate period of eight (8) weeks after production of the purified NRL test materials. A decreased amount of coagulum may reference the addition of surfactant in the stability lot. A maturation period after production was truncated. While for the samples received it is unknown as to the maturation period after centrifugation at the plantation. See Tables 1- 3.
[00257] Physical Properties of Purified NRL after Impurities are Reincorporated. The effect impurities removed during the purification process have on when reincorporated (added back in) to purified NRL. A portion of the impurities accumulated from the disc stack, bowl and heavy phase discharge were retained and reincorporated back into a sample of purified NRL production at various levels of the Step 1-4 process as described FIG.2. Both compound and uncompounded materials were tested to evaluate the effect of impurity loading on physical performance properties of dipped articles. Specific results of these tests follow. See also FIG. l. [00258] Tensile, Compounded. In general, the baseline article produced used the standard compound formula and chemicals (except green testing) with maturated to purify NRL. Other samples taken from the same purification process lot were compounded with differing percentages of impurities with four articles produced and averages noted. As impurities were reincorporated to the purified NRL, the physical properties declined significantly, signifying a correlation between purity levels and performance levels. The test was designed to accept a range of reincorporated impurities: 1.5%, 1.75% and 2.5%. Moreover, for each sample of purified NRL used, four samples were produced and tested with the average noted. See Tables 1- 3.
[00259] Elongation, Compounded. Test results as described above. See - Tables 1- 3. [00260] Green Strength Tensile as Uncompounded. The purified NRL sample with incorporated impurities performed like crude Hevea NRL from prior testing. Additionally, a comparison to the baseline (0 impurities) was performed for the reincorporated purified NRL sample at two different reincorporated percentages: 1.5% and 2.5%. Physical green performance was found like that of the crude Hevea NRL with the higher loading significantly worse. A cast sample was produced by pouring the impurity rich NRL into a mold with 1.5mm thickness. The sample was oven dried at 60C for one hour followed by a few more hours at ambient of 20C. The article was removed from the mold and flipped to ambient temperatures until fully dried. It is noteworthy that some crude Hevea NRL lots (4 in total) contained percentages of Non -rubber Content (NRC) above that of the industry standard and what is found to be typical, or about 2%. Six of the ten lots tested showed green strength as described on the lot individual certificates of analysis (CoA) at an average of 2.23%NRC. Of the ten lots tested, four showed elevated NRC with an average of 3.87% to a high of 4.26%NRC, which is above the 2% industry standard and not the same value noted on the lot CoA. See Tables 1- 3.
[00261] Improved/Increased Centrifuge Operating Period by Means of a CIP System. This test was performed to determine whether there was an operation efficiency change with increased purification centrifuge operation times. It was noted that as Mean Time Between Servicing due to loaded bowl and reduced output for light phase discharge. In addition, wasted ‘cream’ in the bowl cover light phase discharge is reduced due to capture by the CIP.
Results
[00262] Natural rubber latexes were used for testing as described in the Tests section above and described in the Results section herein. Certain NRL samples were taken prior to processing the latex as in purification described herein as well as during the purification process and after. All samples were compounded using a typical dipped article, which was then used for physical testing. Both compounded and uncompounded latexes were evaluated in a similar manner. Tables 3 & 4 are a summary of certain of the tests and samples described herein. [00263] The compound formula used to test the samples consists of 100 NRL emulsion (purified, crude, or low protein), 0.1 Calsoft L-40, 5 Bostex 827, and 1.0 Wingstay L. This compound is a basic compound that utilizes a master batch cure package available from Akron Dispersions (Bostex 827), which is a typical NR cure package for Hevea. This provides acceptable and comparable properties. Twelve dipped sample articles were produced from each compounded batch and tested in the laboratory for tensile, elongation and modulus properties. The data in Table 3 below is an average across all twelve samples produced and tested including those samples with incorporated impurities. The baseline purified NRL was compounded and then separated into four, 1 L samples where different percentages of the impurities were added back in as described above under the testing (1.5%, 1.75%, 2.75%). A dipped article was produced from each on day one, then after three days of pot maturation, and then a series of four test articles were produced from each test sample, cured, dried, and tested for their respective physical properties, the results of which are described in more detail below. Additionally, uncompounded cast films were produced to test green strength.
[00264] Table 5 describes average, high, and low protein content over three samples per material type (n=3). Post compound rise is an indication of the stability of the material’s protein content to increase because of surfactant leaching of protein solubilization. Test is performed two (2) and four (4) weeks after the surfactant is added.
[00265] The lower the Modulus (Mpa) the softer the material. Low modulus correlates with high elongation; and low modulus and high elongation correlates with lower tensile strength. Hence, the methods disclosed herein disclosing methods for production of a purified NR with relative higher tensile strength (Table 3) and low modulus (Table 6) are markedly different . The purified NR filament disclosed herein is therefore softer and preferred while at the same time having high mechanical strength and stability. Until this disclosure herein, such a purified NR with these physical properties has not been described. The tables (data) describe the tensile, elongation and modulus of the purified NR disclosed herein compared to unpurified NR. Table 5: Properties of Purified Natural Rubber Compared to other Natural
Rubber Source Materials
Figure imgf000059_0001
Figure imgf000060_0001
Table 6: Protein Content of Purified Compared to Un-purified Natural Rubber
Figure imgf000060_0002
Table 7: Tensile Strength of Purified Compared to Unpurified or Low Protein Natural Rubber
Figure imgf000060_0003
[00266] S3-X1, X2 are purified NR produced from methods as described herein but are compound formulas to enhance end-product performance properties in certain areas and do not necessarily demonstrate total optimization of the methods disclosed herein. Table 8: Green Strength & Color of Purified Compared to Unpurified Natural
Rubber
Figure imgf000061_0001
Table 9: Elongation of Purified Compared to Unpurified Natural Rubber
Figure imgf000061_0002
[00267] S3-X1, X2 are purified NR produced from methods as described herein but are compound formulas to enhance end-product performance properties in certain areas and do not necessarily demonstrate total optimization of the methods disclosed herein.
Table 10: Modulus of Purified Compared to Unpurified Natural Rubber
Figure imgf000061_0003
Figure imgf000062_0001
Table 11: Average Tensile, Elongation & Modulus of Crude (Unpurified) and
Purified Natural Rubber
Figure imgf000062_0002
EXAMPLE 3 - METHODS FOR PRODUCTION OF A RUBBER FILAMENT FROM A PURIFIED NATURAL RUBBER LATEX SOURCE MATERIAL
[00268] Methods for production of an improved natural rubber fiber/filament relies principally on several factors: (i) High performance source material or NRL with superior physical properties, specifically the PNR or PENRL source material as described in Example 2 and as defined in the application herein; (ii) Scalable process and ready on demand; (iii) Standard equipment to allow for quick adaption and entry into the field as compared to customized standards; (iv) Standard equipment that is easy and economical to modify and/or customize; (v) Common chemical methods and agents for easy adaption or adoption, and with standardized equipment or slightly modified equipment; (vi) Chemistries that do not require organic, inorganic or volatile organic compound (VOC) emitter type of solvents; (vii) Chemistries that do not require catalysts (catalyst free); and (viii) Chemistries capable of allowing the natural rubber fiber/filament to be dyed and color matched to the desired fabric. [00269] Figure 7 describes a general process for production of rubber fib er/fil ament from latex or NRL source material, whereas Figure 8 describes a process for making natural rubber fiber/filament from PENRL source material. Similarly, Figure 8 describes a general process for production of rubber fiber/filament from solid rubber source material, whereas Figures 10 & 12 describe a process for making natural rubber fiber/filament from solid rubber derived from PENRL source material.
[00270] Although this method can be utilized for making rubber fiber/filament from any natural rubber latex source, it is hereby described a method for making rubber fiber/filament from PENRL (1) as described above in Example 2 and also referred herein as “elastomeric source material (1)” or “PENRL source material (1)” or equivalents thereof, is a natural rubber latex that has been compounded to obtain certain physical properties or characteristics of a purified or premium NRL including but is not limited to the following physical properties: 1) the total range of protein content is about 50 ug/g to about 200ug/g; 2- the total solids content (TSC) range is between about 35% to 70%, depending on the process parameters and the desired TSC level for the process or requirements for a machine or industry or field; 3- the dry rubber content (DRC) has a range from about 35% to 70%; 4- the non-rubber content (NRC) has a range of about 0.01 to 1.0%; 5- the pH is a basic pH, for example, the pH is in the range of about 8.0 to 12.0; 6- the viscosity of about 60% TSC centipoise (cP) in an uncompounded form ranging from 35 to 100; 7- the viscosity of about 60% TSC cP in a compounded form ranging from 40 to 200; and 8- the mechanical stability of about 55% TSC, sec. range from 700 to 1,500 sec.
[00271] The NRL or PENRL source material may be further compounded depending on the purity of the source material and the physical properties desired in the product made from the NRL / PENRL (“latex”). Referring to FIG.9 The final latex emulsion compound (4) can be transferred under pressure (4a) to the extrusion unit (5). The transfer (4a) may be accomplished by means of a Sine type Pump unit to ensure proper handling is achieved and limit friction coagulation formation inside the pump, pump head, connecting tubing and pipes, as well as the extruder unit (5) itself. The transfer (4a) may incorporate any number of removable filters (more than one) to further separate the latex according or e.g., pore size. Filter or filters in the transfer unit (4a) may e.g., also capture unwanted coagulant or other foreign material particles from the latex (4) and further clean and purify the source material.
[00272] Still referring to FIG.9, the extruder (5) supplies necessary forming head pressure from an internal pumping supply system, so the transfer (4a) pump is required to supply the required volume of PENRL to ensure the extruder (5) does not run low on PENRL in its internal reservoir tank. The transfer (4a) pump shall supply a volume range from about 0.5 LPM (Liters per Minute) to about 50 LPM. A plurality of pumps may be utilized to adequately flow the desired volume of PENRL. The filter(s) may have about a 600-400-micron size (medium) range. The extruder (5) may contain additional internal filter(s) prior to discharge at the forming extruder injection head (5a).
[00273] Still in one method, the transfer system may contain multiple filtration units in series with larger pore mediums first in series order to a final smaller pore medium prior to entering the extruder injection vessel and discharge pump unit. [00274] Still referring to FIG.9, the PENRL extruder unit (5) ordinarily consists of a reservoir to hold an amount of compounded latex at an appropriate temperature, filter assemblies, internal high-pressure pump, connecting pipe and hoses which transfer the PENRL from the reservoir to the extrusion head (5a). The extrusion head (5a) may consist of one or more small orifice that communicates directly or indirectly with a liquid coagulation bath (6) whereby the extruded and injected latex material is forced under pressure through the orifice located in the extruder head (5a) forming a thin diameter range from about 0.8mm to about 10.0mm length of latex, while instantaneously (rapidly) the exposed latex contacts the coagulation liquid set bath (6) and becomes semi solid or firm. As more latex is exposed to the coagulation liquid set bath (6) the length of the now solidifying thread increases continuously. The coagulation liquid which is low in pH (ranging from about 1.0 to about 6.0 pH) reacts to the latex causing the micro particles to adhere to each other forming a semi solid. The longer the fiber/filament formation remains in the coagulation liquid bath (6) the more solidified the core of the fiber/filament becomes. The solidification of the latex occurs primarily due to the pH of the coagulation liquid set bath (6) rather than the chemistry of the compounding formula. [00275] In one method, the extruder forming head (5a) may contain a multiplicity of forming orifices (openings) capable of producing more than one (1) fiber/filament and up to 1,000 fiber/filaments or more depending on configuration of the equipment. See Figure 8 for diagrams showing a cross-section of a single (A) or multiple (B) fiber/filament configurations.
[00276] The extruder forming head (5a) consists of an exit orifice in a singular configuration. Additionally, the forming head (5a) may be designed with a multiplicity of orifices which produce multiple fiber/filament segments at once. Figure 14 illustrates some non-limiting examples of cross-section configurations of rubber fiber/filaments. Figure 13 illustrates one embodiment of the dimensions of the fiber/filament diameter as a function of the orifice diameter size (single and plurality). The diameter size, to a limited function, is determined by the pressure or force of the latex exiting the forming head orifice (FIG.13, single or multiple), the viscosity of the latex, rheology of the latex and may be altered by manipulating the flow characteristics of the latex.
[00277] The solidifying rubber fiber/filament will become firmer from the outside inward for a period until the entire fiber/filament length solidifies fully. Once fully solidified the rubber fiber/filament may be handled and taken out of the coagulation liquid set bath (6) without tearing apart. The extruder (5) may be fitted with a single fiber/filament forming head, multiple fiber/filaments forming head (FIG.13) as well as multiple heads to produce a multiplicity of fiber/filament lengths simultaneously. There may be an equipment configuration whereby multiple extruders are arranged and communicate to the coagulation liquid bath (6).
[00278] The coagulation set bath (6) contains the coagulation liquid which is a pH- controlled liquid that consists of water (H2O) being most of the bath volume. Chemicals are added to the water to reduce the pH level below about 8.0 pH. The pH of the coagulation liquid may range from about 1.0 to about 8.0 pH and can be adjusted to suit specific fiber/filament production characteristics and parameters. For example, an acid is added to the coagulation water to reduce and control the pH level between about 3.0 to about 6.5, more preferably about 3.5 to about 5.5. Such acids include but are not limited to: Acetic Acid, Sulfuric Acid, Methanoic Acid, Formic Acid, Carbonic Acid, Phosphoric Acid, and/or Hydrochloric Acid [00279] It is also provided that a mixture of two (2) or more selected acids may be utilized to create a coagulation bath liquid suitable to form an exterior solidified skin on the fib er/fil ament length instantaneous to contacting the coagulation liquid by the compounded latex.
[00280] The coagulation set bath (6) may additionally have a system to warm the bath liquid and maintain it at a specific temperature for the duration of the production cycle, or change it gradual (e.g., cooling) for a different purpose or a rubber fib er/fil ament with different physical properties. The bath may utilize an electric heating element affixed to the exterior of the bath walls, steam heat or other suitable methods and accessories to heat up liquids. The bath temperature is maintained at a temperature between its lower and upper set points whereby the range may be from about 20C (68F) to about 100C (212F), preferably between about 48C (120F) and about 72C (165F). A series of thermal probe sensors may be utilized to measure multiple areas of the bath and provide an average temperature. This measurement may be communicated to a control unit, which in turn can control the heating elements to increase or decrease the temperature. A suggested control resolution of the set point may be +/- 10%.
[00281] The extruder forming head (5a) in this configuration is submerged under the coagulation set bath (6) level allowing the ejected latex compound to instantly contact the coagulation liquid. The ejected fiber/filament lengths are continuously exposed to the coagulation liquid upon exiting the forming head. During the start of the production cycle the fiber/filaments are pulled and managed through the length of the coagulation set bath (6), out of the coagulation set (6) bath and onto the fiber/filament separation and training table platform (7), which may be located inside the flash oven and through the entirety of the production system.
[00282] The fiber/filament separation and training table (7) is located at the exit of the coagulation set bath and provided to effectively train or run the fiber/filament upon exiting the coagulation bath(6). In this configuration the fiber/filament is washed with fresh water of a neutral pH prior to entering the flash oven (8). The wash water pH range is between 6.5 to 7.8 pH with a preferable set point being 7.0 pH. In some embodiments, the fiber/filament lengths are stretched by rollers (9) operating at synchronous speeds and in some embodiments at differential speeds which cause the fib er/fil ament to be pulled longitudinally which while in the uncured state cause the fib er/fil ament’ s diameter to reduce. In some embodiments, the fiber/filament length enters a forming ring to reduce its diameter and may repeat this forming ring step multiple times to form the desired fiber/filament cross section. See Figure 9 for nonlimiting examples of various cross-sections of fiber/filament diameters.
[00283] The flash cure oven (8) is located at the exit of the separation and training table platform (7). The oven (8) may in this configuration house the separation and training table platform (7). In some embodiments the flash cure oven (8) is utilized to quickly set the fiber/filament firmness to ensure proper handling of the fiber/filament across the production system and ahead of the final cure oven (10). The flash cure oven (8, 10) may be heated using electrical heating elements, UV lights, infrared lights and microwaves or a combination thereof two or more energy supplying methods. The flash cure oven (8, 10) can provide the necessary temperature within the unit in a range from 40C (104F) to 150C (300F) and is able to maintain a temperature set point more preferably of 100C (212F) and hold a resolution of +-10%. In some embodiments the oven is not utilized due to the strength of the fiber/filament exiting the coagulation bath and is dependent upon the latex compound formulation and time spent in the coagulation bath.
[00284] The use of forming rollers (9) is provided as a method of further forming the fiber/filament’ s cross-sectional shape. As the fiber/filament is uncured, the fiber/filament material may be deformed in such a manner as to set a cross-sectional shape. A single roller or a multiplicity of rollers may be established in this configuration.
[00285] A curing oven (8, 10) is provided to fully cure, set, and vulcanize the fiber/filament in a finished condition. The oven may be heated using electrical heating elements, UV lights, infrared lights and microwaves or a combination thereof two or more energy supplying methods depending on the cure chemical system selected during compounding. For a typical heat cure compound system, the curing oven may have a temperature range from 120C (248F) to 150C (300F) preferably with a set point of 130C (266F).
[00286] In one method, the fiber/filament will reside (dwell) in the oven (10) for a period of time necessary to fully cure the fiber/filament latex compound and may range from 5min to 20min with a more preferably set point period of lOmin depending on thickness of fiber/filament, curing agent used and performance characteristics of the fiber/filament required. In some embodiments, the curing oven (10) is configured to have a multiplicity of rollers whereby the fiber/filament length is wrap around such a roller to increase the total length of the fiber/filament in the oven at one time and operates at such a speed to coincide with the time period of the cure. The cure oven (10) may contain several linear feet of fiber/filament or in some embodiments and design configurations may contain several hundred (100) linear feet of fiber/filament. In one method, the speed of the fiber/filament moving through the oven may be in millimeters per minute to millimeters per hour and range from ten millimeters per hour to ten millimeters per minute or faster depending on the desired cure condition of the fiber/filament. In some embodiments, the curing oven may utilize forced flow of air to enhance curing of the fiber/filament.
[00287] Methods are also provided for coating the rubber fiber/filament in a fiber/filament coating bath(s) (11) to prevent the fiber/filaments from sticking together when wound on the finish uptake spool (17). Additional fiber/filament coating bath(s) (11) may also serve the purpose of providing a required finish rubber fiber/filament, for example, one that offers low friction or other characteristics. A variety of coatings, both wet and dry, are suggested including but are not limited to talc (dry), silicone (wet), paraffin wax (wet), polymer (wet) and/or natural material e.g., cotton, or any combination of these.
[00288] Other coating types and systems may be utilized to impart specific performance characteristics as is required by the finished fiber/filament application. In one method, the coated fiber/filament may exit a bath, be dried, and reenter a secondary coating bath prior to exiting and drying. In another method, this process may be repeated any number of times to achieve the desired fiber/filament properties. In still another method, the type of coating may change each coating performance, such as a silicone coating followed by a talc final coating or any combination thereof. In still another method, the fiber/filament coating thickness is measured by noncontact laser measurement in combination of optical vision system which monitors and records each length of fiber/filament at desired intervals. [00289] In certain fiber/filament designs where specific performance characteristics are required a secondary operation is needed. Such fiber/filament configurations may include an external fiber/filament wrapping of polyester, nylon, cotton, or other suitable fibre as the fiber/filament type requires. The fibre outer wrapping occurs after the fiber/filament has finished its curing cycle in the curing oven (10) where the cured fiber/filament is spooled up prior to entering the merging head system (16). The wrap operation may be accomplished without the use of an uptake spool and be performed continuously upon exiting the cure oven. An alternative fiber/filament configuration may require the addition of a second elastomeric coating of natural rubber latex. In one method, once the perimeter fibre is wound on to the fiber/filament core the fiber/filament is coated to protect the fibre/fiber/fil ament unit.
[00290] The outer wrap fibre spool (14) is provided as a method of outer wrap fibre for the merging head and performs as a continuous feed supply with tension management. The outer wrap fibre (14) may utilize cotton or silk, polyester, or nylon, and may be wrapped around the fiber/filament core with a specific number of wraps per inch and in some embodiments use a woven fibre sleeve. In some embodiments the wraps per inch may range from 1-WPI to 5-WPI and depend on the application of the fiber/filament and its suitability or performance. The cured fiber/filament may then be wrapped with fibre prior to or after application of the fiber/filament coating as performed in the fiber/filament coating bath(s) (11).
[00291] The merging head (15) provides a method for the outer fibre wrap (14) to be properly wrapped around the fiber/filament core in a spacing appropriate to the final fiber/filament configuration. The specification is wraps per inch (WPI) or may utilize wrap per millimeter (WPM). In an alternate configuration the merging head (15) may be utilized to combine multiple fiber/filaments to form a single, multi-layer fiber/filament piece. The multi-layer fiber/filament piece may then be wrapped with fibre to form a specific configuration. In one method, the fiber/filament may be wrapped with one fibre or a multiplicity of fibres depending on the desired fiber/filament performance and application.
[00292] The finished fiber/filament uptake spool system (17) provides for a single or multiplicity of fiber/filaments to be wound onto a finish spool as a completed product suitable for packaging and shipping or as an intermediary transfer hold prior to additional production work.
[00293] In another method, the final product rubber fiber/filament, coated or uncoated, by one or more coat layers, there is provide a pre-tensioning unit (18) to ensure finished spools are wound to a correct fiber/filament tension. And a further fiber/filament uptake spool system (19) like the above-described fiber/filament uptake system (17) may be added singly or a plurality.
[00294] Still in one method, an alternate finishing process(es) may occur at multiple locations throughout the process as described herein and in Figure 5 including but not limited to: 1- Prior to entering the final curing oven (10); 2- Post curing oven (10); 3- After the outer fibre wrap (14) is incorporated; 4- After the fiber/filament coating (11) has been applied to the fiber/filament; 5- After exiting the drying oven (12).
Any of the methods described herein, intended, or discovered in the future will aim to have one or more of the above parameters, alone or in combination.
EXAMPLE 4 - EXTRUDABLE METHODS FOR PRODUCTION OF NATURAL RUBBER FILAMENT FROM PURIFIED NATURAL SOLID RUBBER
[00295] In addition to production of natural rubber fiber/filament from a natural rubber latex as described in detail in Example 3, methods herein describe production of natural rubber fiber/filament from a natural solid rubber. Figures 8, 10 and 11 describe such methods.
[00296] The natural rubber filament made from PENRL described in Examples 2 and 3 is based on a purified natural rubber latex that has been coagulated, dried, and formed into bales as a solid. The solid rubber is compounded with specific chemical ingredients necessary to assist in producing a finished sheet ribbon that is thinly sliced into fiber/filaments. Referring to Figure 6, in one method of the invention, the fiber/filament is formed by extruding a thin sheet of compounded PEN solid rubber (PENSR, 3) through an extruder (4, 4a) forming mold whereby the thickness may range from about 1.0mm to about 10.0mm and with a width of about 250mm to about 1,000mm and in a continuous length as defined by the production batch size. The extruded sheet (8) is sliced into smaller individual fiber/filament portions by means of a sheet cutter that first forms a ribbon which is then feed into the fiber/filament cutting tool which cuts the individual fiber/filaments. The cutting tool may be adjusted in such a manner as to provide the size of the individual fiber/filament portion. The cutting of the fiber/filament portions may be accomplished prior to or post curing (7) depending on the desired performance of the fiber/filament portions. [00297] In one method, the extruded sheet may be compounded as a solid, while in other methods a blowing agent may be used which imparts small bubble pockets providing a closed cell foam. Both solid and closed cell foam rubber fiber/filaments formed from the sheet and ribbon method from a PENSR source material offer unique physical properties and performance characteristics as desired by the product application, for example, elongation (elasticity), modulus and compression set performance.
[00298] In one method of the invention, the PENSR is the significantly reduced levels of detectable total proteins whereby the total protein content is lower than 200ug/g, preferably lower than 100 ug/g, and more some specifications or applications, preferably lower than 50 ug/g.
[00299] In one method, if a PENSR and/or PENRL are not available, other commercially available Hevea latex’ like those indicated in Table 1, Example 2, may be selected and coagulated to form a solid rubber feedstock including but not limited to other now commercially or in the future available natural rubber latex (or a type 1 latex) has not been clumped or flocculated or has had substantially all of the magnesium removed to produce a natural rubber fiber/filament with the present described physical properties. See Table 12, which describes ranges of certain physical properties, depending on the desired application e.g., including tensile strength (about 11-100 Mpa), elasticity or elongation (200-750%), heat resistance (greater than 650 F), and duromoter (20-90 Shore A). In one method, a type 2 latex where the material has been clumped or flocculated and most of the magnesium removed may make a natural rubber fiber/filament with the present described physical properties. In another method, a double or triple centrifuged NR latex may produce a natural rubber fiber/filament with the present described physical properties. Table 12: Desirable Physical Properties of natural rubber fiber/filaments of the present invention
Figure imgf000072_0001
[00300] The compound formula determines the physical properties and performance of the finished fiber/filament as designed for the end application. It is standard in art that the physical properties are defined as having a specific range, e.g., range of elongation (stretch), modulus, and recovery from elongation, durometer (firmness), color and other performance characteristics.
[00301] Referring to Figure 10, purified natural solid rubber or PENSR may be compounded (2, 2a) in a variety of ways to promote the desired physical and visual characteristics required for the end applications. The following base formula is provided as a guidance and reference, but it will be clear to one skilled in the art of rubber compounding those modifications of the described formula are within the scope of the present invention. Table 13: Base Formulation for Compounding Purified Natural Solid Rubber (PHR)
Figure imgf000072_0002
Figure imgf000073_0001
[00302] The base formulation above in Table 13 may consist of other agents or chemicals used to enhance physical and/or visual characteristics in the finished fib er/fil ament, e.g., see Table 12. [00303] In other embodiments, the formulation consists of at least a vulcanization agent, wherein said vulcanization agent is Sulphur at a weight concentration in said natural rubber set between 0.5% and 3.0%; a vulcanization accelerator and a vulcanization activator; an anti-tacking agent; an antioxidant agent; and a stabilization agent. Additionally, other properties for weather protection such as UV stability can be added accordingly for certain applications, and such is described above herein.
Table 14: Agents for Compounding Purified Natural Solid Rubber (PHR)
Figure imgf000073_0002
Figure imgf000074_0001
[00304] For example, in one method of the present invention, a blowing agent may be incorporated in the final batch mix with the curing agents. When blowing agents are utilized the sheet extruded is held in a captured mold between heated plates until the blowing agent reaches the desired temperature and decomposes forming individual gas pockets. In another method of invention, the formula compound may replace sulfur-based cure agents with peroxide cure agents.
[00305] Still in another method, the compounding is performed in stages with ingredients added and mixed with an extrusion stage to remove entrained air. This form is allowed to rest for a period ranging from about one (1) hour to twenty -four (24) hours prior to the addition of the curing agents. The agents are added and mixed, then extruded to remove any entrained air pockets. The curing agents are incorporated then the compound batch is placed into the sheet extruder. In typical compounding the mix is performed in multiple stages: 1) A premix stage that masticates the solid rubber to reduce the original Mooney (viscosity) to a lower number suitable for mixing and compounding; 2) The fillers, stabilizers, process oils, clays, and colors are combined to form a batch; 3) The rubber compound is then extruded to remove air pockets and then allowed to rest; and 4) The preform mix is then remixed with active ingredients such as activators and curing agents, then extruded again to remove air pockets.
[00306] Again, referring to FIG. 10, the extruder unit (4) ordinarily consists of a reservoir hopper to hold an amount of compounded rubber at an appropriate temperature, internal high pressure ram assembly, connecting chamber from the reservoir to the extrusion head (4a). Similar in concept to that described for fiber/filament production from latex in Example 3, the extrusion head may consist of one (1) small mold opening or a multiplicity of mold formers (FIG.9) that forces the compounded rubber through the opening or openings to form a thin sheet of desired width out of the forming head onto an intermediary table conveyor. The movement of the conveyor is synchronized to accommodate the extruder output to ensure the sheet flows, remains flat and does not bind or wrinkle.
[00307] In one method of the present invention, the extruder forming mold may emboss fiber/filament deformation into the sheet or ribbons to assist in slicing of the fib er/fil ament portions. See Figure 7, where dimension A is performed by the extruder forming head or by a forming roller (FIG.11 A). The forming mold imparts a shape on both top and bottom of the sheet and/or ribbon (FIG.1 IB). The extruder head (4a) may be of the heated type or cold type depending on the sheet compound where such heated head assists to start the curing process and reduce the viscosity of the compound to aid in material flow through the mold head.
[00308] In some embodiments, the sheet or ribbon may be formed between two (2) or more configured rollers to assist in shaping the individual fiber/filament cross sections.
[00309] The separation conveyor table receives the extruded sheet upon exit from the extruder. The conveyor table moves at the appropriate speed in inches per minute to coincide with the extruded sheet speed. In some embodiments, the extruded (and uncured state) may be moved through an array of rollers to force the thickness of the sheet to become thinner and where required the sheet may be sliced widthwise to form a smaller width ribbon to assist in downstream handling.
[00310] A curing oven (7) is provided to fully cure, set, and vulcanize the fiber/filament in a finished condition. The oven may be heated using electrical heating elements, UV lights, infrared lights and microwaves or a combination thereof two or more energy supplying methods depending on the cure chemical system selected during compounding. For a typical heat cure compound system, the curing oven may have a temperature range from about 120C (248F) to about 150C (300F), preferably with a set point of about 130C (266F). In one method, the fiber/filament will reside (dwell) in the oven for a period of time necessary to fully cure the fiber/filament latex compound and may range from about 5min to 20min, preferably, 10 minutes or for whatever time is necessary to effectively cure the fiber/filament of a certain thickness and for additional manipulation. In one method, the curing oven is configured to have a multiplicity of rollers whereby the fiber/filament length is wrap around such a roller to increase the total length of the fiber/filament in the oven at one time and operates at such a speed to coincide with the time of the cure. The cure oven may be several feet in length depending again on the application, with an average length of about 50 to about 100 feet in length.
[00311] The cured sheet and/or ribbon is presented to the cutting tool array (8) where the sheet and/or ribbon is sliced into the appropriate individual fiber/filament portions depending on the desired fiber/filament product and application. The rubber fiber/filament sheet may be sliced into a width of about 0.15mm to about 50mm or more depending on product design configuration. One skilled in the art will understand that the fiber/filament width is dependent on the desired use or application of the rubber fiber/filament. And ribbon in 0.5mm increment, for example, 0.5mm increments, 1.0mm increments, 1.5mm increments, 2.0mm increments and the like. Further, that the width range may be wider 500mm and subsequently sliced into smaller width increments depending upon desired product design.
[00312] In one method of the present invention, the fiber/filament coating bath (9) is provided to coat the fiber/filament to prevent the fiber/filaments from sticking together when wound on the finish uptake spool (11). Additional purpose is to provide a required finish offering low friction or other characteristics. A variety of coatings include but are not limited to dry coating agents such as talc and wet agents such as silicone, paraffin, polymers and/or any combination thereof. For example, a silicone coating may be followed by a talc coating which may be further coated by another wet or dry final coating or any combination thereof to achieve a desired property.
[00313] Other coating types and systems may be utilized to impart specific performance characteristics as is required by the finished fiber/filament application. In one method, the coated fiber/filament may exit a bath, be dried, and reenter a secondary coating bath prior to exiting and drying. In other methods, this process may be repeated any number of times to achieve the desired fiber/filament properties. In some embodiments, the fiber/filament coating thickness is measured by non-contact laser measurement in combination of optical vision system which monitors and records each length of fiber/filament at desired intervals. [00314] The drying oven (10) is utilized to dry and finish the fiber/filament coating system and may use forced warm air in a configuration typical to drying typical coating systems whereby heated air flow is required. For systems that do not require heated air a cool air system may be employed. And the finished fiber/filament uptake spool system (11) provides for a single or multiplicity of fiber/filaments to be wound onto a finish spool as a completed product suitable for packaging and shipping or as an intermediary transfer hold prior to additional production work.
[00315] Those familiar in the art of rubber compounding and rubber fiber/filament materials, will understand that the present invention is not limited to the described formulation, agents and ingredients, equipment and tools described herein, and that other formulations, agents and tools may be utilized to produce fiber/filaments with different physical performance characteristics to which a wide variety of additives and ingredients without deviating from the scope of the present invention.
EXAMPLE 5 - METHODS FOR PRODUCTION OF NATURAL RUBBER FILAMENT BY ELECTROSPINNING
[00316] High performance natural rubber fiber/filament fibres and non-woven rubber fiber/filament made from a similar purified elastomeric natural rubber (PENR, solid or latex) as described above in Examples 2-4. If the source material is a PESNR, it is dissolved using a range of solvents to form a solution which can be further compounded e.g., additional chemicals, fillers, curing agents and the like to form a final fiber/filament forming solution that is conductive. Electrospinning technologies use electric force to draw charged fiber/filaments of polymer solutions or polymer melts, for example, natural rubber fiber/filament, into fibre diameters in the order of some hundred nanometers. Electrospinning shares characteristics of both electro spraying and conventional solution dry spinning of fibres. Electrospinning has advantages over extrusion or other processes described above or elsewhere because it does not require the use of coagulation chemistry or high temperatures to produce solid fiber/filaments from solution. Thus, making the process particularly suited to the production of fibres.
[00317] Electrospinning is a simple electrohydrodynamic process used to produce fibres. It produces fiber/filaments, fibres and fibrous membranes which are employed in a wide range of applications, from tissue and/or material engineering, drug delivery to energy conversion and storage. Electrospinning uses a high voltage applied to a liquid droplet or solution, which causes the liquid becomes charged and electrostatic repulsion counteracts the droplet surface tension thereby stretching the droplet and at some critical point a stream of liquid erupts from the surface at the discharge site or Taylor Cone. The range of these fibres is 100 of nm to 10's of pm and the fibres are typically collected in the form of a non-woven membrane.
[00318] In one method, the geometry of the Taylor Cone can be modified to suit the desired fiber/filament size, purpose, or application. The Taylor Cone geometry is governed by the ratio of surface tension to electrostatic repulsion. And one skilled in the art can modify the geometry of the Taylor Cone to suit the intended purposes. For example, Figure 15 shows one method for using electrospinning technology to form very small diameter natural rubber fiber/filaments. The fiber/filaments or fibres discharged at the site of the Taylor Cone (C) are attracted to the forming plate (or collector, A) opposite the cone, is negatively charged and moves in three axis (X, Y & Z) to collect the fiber/filament fibres and arranges them according to the desired design features, e.g. as a non-woven flat membrane.
[00319] Referring again to Figure 15, the solid rubber is mixed with a non-polar solvent or mixture of solvents suitable to dissolve the rubber forming a solvent/rubber solution. This solution is then forced through a series of small openings in a forming head or spinneret. The forming head is elevated to a height which allows the ejected solution to be pulled by electromagnetic conductivity downward through a heated chamber, through the Taylor Cone (C) whereby the fiber/filament fibre length is collected on a forming collection plate (A) which can move in three axes. In another method, the forming plate (A) has a by-pass configuration (B) which is still negatively charged to attract the fibre leaving the Taylor Cone (C), but by-passing collecting on the forming plate and passing directly through to a curing and drying oven (D) where the fiber/filament fibre is solidified and wound.
[00320] While the solution is in the heated chamber the solvent portion of the solution begins to evaporate causing the fiber/filament to become solidified (D). The evaporating solvent is removed from the chamber and recovered by condensation for reuse. The fiber/filament length at the bottom of the heated chamber is eliminated of solvent forming a fiber/filament capable of being maneuvered into and through a washing bath. The fiber/filament diameter is determined by the amount of solution discharged by the forming head, the length of the heated chamber, the speed in which the fiber/filament solution drops in addition to the starting solution viscosity among other solution and equipment parameters. As the solvent reduced fiber/filament is pulled by the roller arrays through the washing bath the fiber/filament enters a curing oven to ensure the polymers become cross linked and the fiber/filament’ s physical characteristics improve. As the fiber/filament is cured the equipment provides for additional processes such as coatings, fibre wrapping and wind up to finish fiber/filament uptake spools.
[00321] In one method of the invention, various solvents or mixtures can be used to convert the solid natural rubber to a liquid solution including but not limited to cyclopentane, hexane, cyclohexane and/ or toluene. However, other suitable nonpolar solvents may be utilized. A ratio of solvent to solid rubber by mass can be identified which provides enough solvent to effectively reduce the rubber to form a viscose solution. Additionally, other additives that improve fiber/filament elongation, tensile, recovery after elongation, compression set, color retention, and other specific characteristics may be added to the solution as well. For example, the solution may contain carbon nano tubes and fibres which improve electrical conductivity while enhancing the physical performance of the fiber/filament fibre characteristics.
[00322] In one method of invention, modification of the spinneret and/or the type of solution can allow for the creation of fibres with unique structures and properties. Electrospun fibres can adopt a porous or core-shell morphology depending on the type of materials being spun as well as the evaporation rates and miscibility for the solvents involved. For techniques which involve multiple spinning fluids, the general criteria for the creation of fibres depend upon the spinnability of the outer solution. [00323] In one method of invention, coaxial, emulsion, electroblowing and ablative electrospinning technologies are contemplated. See the world wide web description for electrospinning, en.wikipedia.org/wiki/Electrospinning. Coaxial electrospinning is a dual-solution feed system which allows for the injection of one solution into another at the tip of the spinneret. More advanced setups, such as a triaxial or quadaxial (tetra- axial) spinneret can be used with multiple solutions. Figure 16 shows the crosssection of a coaxial electrospun fibre or fiber/filament.
[00324] In one method of the invention, a coaxial forming head or spinneret is utilized with a compounded solid version of the PESNR is forced and presented to the flow of solvent which dissolves and ablates the solid rubber and is pulled towards the collection plate below the forming head. As the material dissolves the coaxial solvent flow creates a fiber/filament as it washes over the solid material. Both the solvent and the material are formulated to be electrically conductive. As the fiber/filament is formed downward the carrier solvent evaporates causing the filament to solidify.
[00325] In one method of the invention, an emulsion electrospinning technology can be utilized. For example, emulsions can be used to create core shell or composite fibres. A water phase and an immiscible solvent phase are mixed in the presence of an emulsifying agent to form the emulsion. Any agent which stabilizes the interface between the immiscible phases can be used including but not limited to surfactants and even nanoparticles have been used successfully. During the electrospinning process the emulsion droplets within the fluid are stretched and gradually confined leading to their coalescence.
[00326] In one method of the invention, PE solid rubber emulsions may be used to form a continuous length of filament by a combination of electrospinning and pneumatically assisted/forced discharge at the nozzle forming head to form the filament.
Compounding for Electrospinning, Ablative & Electro blowing Formation [00327] The process for and production of fiber/filament obtained by electrospinning whether utilizing a single type forming head nozzle spinneret configuration or coaxial, triaxial or tetraxial heads requires the ability to solidify the fiber/filament. Solidifying the fiber/filament rapidly is paramount due to the requirements for manipulation of the fiber/filament over a longer and more configured series of devices, rollers, and application mechanisms. For non-woven sheet fabrics, filter media, drug eluding threads or mats, cosmetics, wound care and furthermore, the needs to solidify is less of a concern and therefore the compounding is divided into to two (2) categories: Rapid curing and absolute curing. [00328] In a rapid curing system, the fiber/filament discharged by the forming head spinneret rapidly converts from a semi solid, gel-like or solution form to a more solidified material that is easier to handle due to its firmness. A wide variety of rapid curing agents may be selected for this application including but not limited to a sulfur cure system such as a sulfenamide (TBBS) with TMTD, or MBTS /thiuram with the ultrafast accelerators. The curative agent may also be a UV rapid curing system suitable for a non-polar solvent system, a water-based latex-like system or combination thereof as would be the compound for sulfur-based agents. Still, in another method, a curing chemistry to crosslink the rubber to obtain the optimum elastic and strength properties of the rubber can be achieved.
[00329] In one method, the fiber/filament compound may contain a range of purified natural rubber content (PNRC) from 1% to 100% as a base compound reference using Parts per Hundred Rubber (PHR) as the defining compound metric. To this base chemical agent utilized for curing such as sulfur with specific accelerators, and protective agents required to offset oxidation from oxygen (antioxidants), ozone (antiozonants), anti-aging such as heat, light, and UV wavelengths (except where such protectants interfere with required UV curing agents. In some embodiments, the compound may include rheology agents to modify the flow of the fiber/filament compound through the forming head spinneret helping to form a drawing cone shape.
[00330] In one method of the invention, the compound contains fillers, short and long nano-fibres, nanotubes and other fillers which provide additional physical strength, production handling characteristics, including electrical conductivity necessary to effectively attract and excite the compound through the forming head towards the collection forming plate utilized for non-woven fibre sheets or fabrics and a collecting plate with by-pass opening for continuous forming of fiber/filament. The by-pass collector plate (FIG. 15, B) opening may in some embodiments be ringed by electromagnets which attract or repulse the fiber/filament as it passes through the plate opening in order to control the flow of the fiber/filament allowing it to be drawn through from a liquid like material, become solidified and firm which is required for a continuous formation length of fiber/filament. Control of the electromagnets is performed by a control unit and computer with necessary switching circuitry and software.
[00331] The compound containing fillers necessary to impart electro conductive characteristics may be compounded in such a manner as to be immiscible with the base rubber mixture for the purpose of removal and washing as secondary stages where such fillers may detract from the desired end product’s performance characteristics. In some embodiments multiple compounds may be utilized to create a coaxial fiber/filament design whereby the center core is one material, the outer coating is a different material and as such continues to the extent of the forming head spinneret is capable of.
[00332] In still another method of the invention, the coaxial fiber/filament may undergo post-pulling coatings. For example, the center core may be of PNR or other while subsequent layers or coatings may be of similar or dissimilar material compounds depending on the desired physical performance characteristics. In some embodiments the final layer coating may be defined as a dissolving or eluding medicines and be applied to the fiber/filament during the discharge of the forming head spinneret compounds and/or by downstream processes.
[00333] A wide variety of coating types may be utilized that control the rate of elution while offering protection from thread sticking during mat or fabric formation and/or during continuous fiber/filament formation. In some embodiments, the protective coatings may be washed off prior to final product production whereby a protective coating is undesirable.
[00334] In one method, the fiber/filament is produced using a coaxial forming head spinneret or postproduction coatings, the center core material is washed out forming a hollow fiber/filament with a central void. See for example Figure 13 for a crosssection of a hollow nano and near nano fiber/filament. Such hollow voids act as capillaries to locomote liquids, molecules in multiple manners whereby the certain sized molecules fluids or liquids may be blocked while smaller sized fluids are allowed to pass. The void is produced by washing out the center fibre.
[00335] Based on the method of production utilizing electrospinning singular or coaxially, ablative, electroblowing or assisted pneumatic combined with electrospinning and or other configurations of equipment setup in conjunction with specific compounding formulations to produce fiber/filament in a continuous form length or as non-woven fiber/filament mat sheets as fabrics utilizing a PENR.
EXAMPLE 7 - METHODS FOR PRODUCTION OF NATURAL RUBBER FILAMENT FROM PURIFIED NATURAL RUBBER LATEX BY PREVULCANIZING THE NATURAL RUBBER LATEX EMULSION
[00336] Latex threads (filaments) are produced by continuous extrusion of compounded latex into a wet coacervant (aqueous phase rich in macromolecules such as polymers, proteins and the like) bath (e.g. about 20 - 40 % acetic acid) and followed by washing with hot water, drying at 60 - 80°C in hot air and vulcanized at about 120 - 130°C in hot air. The vulcanized thread is then passed through a bed of talc and wound on to bobbins or drums and post-cured at about 60°C in hot air for about 24 hrs.
[00337] As used herein, thread and filament are interchangeable.
Latex Compounding
[00338] As described herein, the latex (natural or synthetic) should be free of nonrubber constituents, including the PENR or PNR described herein. It is noteworthy that a non-PENR may not provide the fine denier filaments with similar properties as those filaments made using purified natural rubber. The PENR is remarkably different than other commercial forms of NR on the market and is distinguished from other non-PENR or concentrated forms of NR. Refer to Example 2.
[00339] Unlike synthetic latex and polymers, natural rubber latex compounding will depend in part on the type of NR used. For the most preferable physical properties, the general compounding formulation should have minimum number of additives in solid form and dispersions of compounding ingredients should be very finely grounded or milled during the initial mixing or ball milling process. It is also preferable that latex compounding dispersions be free from air bubbles / frothing to reduce or eliminate air entrapment. Before extrusion, remaining or existing air bubbles in the latex compound may be passed through a very fine mesh and allowed to de- aerate by application of partial vacuum or other means to remove air bubbles. Coacervant (acetic) bath
[00340] Acetic acid, a weak monocarboxylic acid, is used to make a coacervant bath by diluting at 20 % - 40 % range. Other weak acids (deprotonate) that are soluble in water may be substituted and boiling or heating temperatures may vary in view of the property of the weak acid.
[00341] Similarly, depending on the NR rubber filament diameter desired, immersion of the in coacervants may be necessary, and higher (large diameter filament) or lower concentrations of acetic acid used. However, the outside surface of the coacervants may form a thin-walled rubber film on the surface while the interior latex compound is still in fluid form or phase. In other embodiments, saline solutions may be preferred for thicker diameter filaments as they effect rapid setting. In other embodiments, when a blend of acetic acid and saline solution are used, the external skin formation on the latex filament is immediate. This skin acts as a semi-permeable membrane and solidification of the filament may be accelerated by water that is lost from the filament. The coacervated batch should be well monitored and controlled throughout the process as consumption of acetic acid will change the milieu of the bath.
THREAD / FILAMENT EXTRUSION
[00342] In one embodiment of the invention, the extrusion nozzles are made from boro silicate glass capillaries with accurate dimensional control, which are then fused into wider glass delivery tubes. Several sets of nozzles of different bore sizes are used as per the finished product, diameter requirements. By varying extrusion conditions, it is possible to use a single nozzle to produce extrudates in a range of diameters. The exact size of diameter of the extrudate depends on parameters that include but are not limited to the nozzle radius (r-cm ), nozzle length ( 1-cm ), di (density of latex compound), d2 (density of resultant thread), h (pressure in cm of the compound at which the latex is extruded), q (the viscosity of latex compound in centipoises, s (the factional solids content in the compound and v (the speed in cm/sec at which the thread is delivered from drying and curing belts).
[00343] The diameter D (in cm) of the circular cross section of the latex filament delivered from the nozzle can be described using the following equation.
Figure imgf000085_0001
[00344] This equation indicates the factors to be controlled to obtain latex filament of given size from a particular size of nozzle.
[00345] Additionally, feeding the nozzle through a tank, which receives latex from a constant - head device, ensures constant extrusion pressure.
[00346] Viscosity of the latex compound should be well controlled for total dimensional control of the product.
[00347] After the coacervant batch the filaments are passed through a hot water bath where water-soluble impurities are leached out. The filament is strong at this stage and is subjected to a stretching process to determine the final diameter. The filament is then carried to a hot air chamber for drying and vulcanization. The hot air chamber has a drying zone maintained at approximately 70°C and the vulcanization zone is at about 125 - 130°C, although temperatures can vary in view of the compounding mixture and the purity of the PENR. Between the two zones one more zone is maintained at intermediate temperatures between about 70°C and 120°C.
[00348] The total time in the vulcanizer will depend on the diameter of the filament, typically between 5 to 7 minutes. However, the filament should preferably be thoroughly dried before it reaches the vulcanization zone.
[00349] The filament is then passed through a bed of talc and is inspected for defects on an inspection table as part of the continuous process before it joined to form a 40-end ribbon or wound on bobbins or drums under slight tension. The ribbons, bobbins or drums are finally post cured at about 60°C in hot air ovens for 24 hr. to complete the cure cycle.
[00350] Various other quality control tests are then carried out. The compounds must be designed to withstand degradative forces such as solvent resistance, detergent resistance, superior aging properties, etc. by employing potent non-staining type antioxidants. RESULTS
[00351] The below tables show the results of various trials of natural rubber filaments made from PENR as described herein and compared to commercial filaments from non-PENR natural rubber.
[00352] The relationship between modulus, tensile strength and elongation is complex and depends on the specific materials. As materials become stiffer and stronger (modulus and tensile strength) it affects the strain or elongation, which is measure of how much any material can stretch or deform before breaking. Material microstructure and processing will affect this, but for this application: When the modulus and tensile strength go up, elongation goes down; and when modulus and tensile strength go down, elongation goes up.
[00353] Further Count (length per weight) and Denier (linear density) values are not necessarily inversely related either, as that will depend on the specific materials, but for this application: When the Count goes up, the Denier goes down; and when the Count goes down the Denier goes up.
[00354] Calculation of a Denier (Man-Made Fibres): Weight in grams per 9000 meters of fibre. Conversions: Denier = 0.354 x Micronaire value. Micronaire value = 2.824 x Denier. Examples include but are not limited to: 80 count = 239 D; 90 count = 225 D; 110 count = 377D; 120 count = 317 D; 140 count = 233 D; 150 count = 203 D; 160 count = 178D; and 170 count = 158 D.
Table 15: Comparison of Natural Rubber Fibers/Filaments Made from Unpurified and Purified Natural Rubber Latex
Figure imgf000086_0001
[00355] Test trials: A (unpurified natural rubber latex, control) ; Bl- B3, Cl- C2; D; and El & E2 (purified natural rubber latex). The Denier is approximate as the size varies along the long filament, and for the above trials it is about 185-190 Denier.
[00356] The elongation (strain) values for the trials El and E2 are higher than trials Bl, B2, B3, Cl, C2 and D, due to changes in formulation and process conditions, demonstrating that physical properties of the filaments can be modified and for function and performance. The increase in elongation values also corresponds to lower tensile strength and modulus, and that is observed in all the trials A through E. Hence, Table 16 shows that the same count or denier filament can have different properties based on small changes to formulation and process conditions over periods of time.
Table 16: Comparison of Natural Rubber Fibers/Filaments Made from Unpurified and Purified Natural Rubber Latex at Different Time Periods
Figure imgf000087_0001
[00357] Table 16 also shows that trials Bl and B2, having similar formulation and processing, do stabilize based on the parameters of modulus, tensile strength, and elongation. Example 8: Fine Denier Natural Rubber Filaments compared to fine Synthetic Denier
FIBREs
Table 17: Spandex (LYCRA) Elongation
Figure imgf000088_0001
[00358] Table 17 was compiled from specification sheets from the manufacturer. The ranges are reported by Lycra. The low value is the lower limit, and the higher value is what the product aims for. The values for the invention’s filament are from Table 15. Table 17 shows that the elongation of Lycra goes up as the denier goes up (count goes down). Comparing 180D Lycra to 190D natural rubber, the natural rubber filament has a greater elongation (strain) range (delta 224), even if accounting for the higher denier, than Lycra spandex (delta of 137 for 180D-IM732 LYCRA). This states that fine natural rubber filaments have unique properties not duplicated by synthetic fibers.
Table 18: Spandex (LYCRA) Tensile Strength
Figure imgf000088_0002
[00359] Table 18 compares the tensile strength of the invention’s natural rubber filaments compared to Lycra fibers. Again, even accounting for different deniers, the tensile strength of 180D Lycra is higher (stiffer) compared to 190D natural rubber filaments, which is lower with a range between 175-330, but after 14 days stabilizes to 383. Thus, there may be applications where substituting spandex for natural rubber filaments of the invention may be suitable, and other applications where one or the other is best suited.
[00360] The objective of the invention was to produce never shown a fine natural rubber filament for various uses. It was not necessarily just to substitute or replace spandex or other PU or petroleum based fine fiber, because the properties for a natural vs synthetic product in this instance are significantly different.
[00361] Prior to this invention, production of natural rubber filament diameters of 110 count and higher (or 377D or lower) was not possible and therefore not commercially available despite the demand for more sustainable and biodegradable products and components. There were perceived limitations of natural rubber and natural rubber latex.
[00362] In one embodiment, natural rubber filaments are made from purified natural rubber latex. In other embodiments, formulation and process changes with regular natural latex may be used to accomplish the same fine denier natural rubber filament.
[00363] Commercially available natural rubber latex is not purified to remove the non-rubber particles including dirt, oil, minerals. Applicant’s PCTUS2021/040085, filed July 21, 2021, and published as W2022/006393, is the first disclosure of the purified natural rubber latex with greater than 90% purity or protein-free. This purified natural rubber lates used in these studies and incorporated herein by reference in its entirety.
[00364] Applicant’ s hypothesized, that the principle reason that finer denier natural rubber threads were not practical is that the impurities and high percentage of nonrubber components in commercially available natural rubber latex directly contributes to low performance of e.g. the breakage of the thread under normal use or when tested for elongation and elongation break or stress at elongation of 300, 400 and/or 500% as tested regularly for other natural rubber threads.
[00365] Spandex type fibers are different from the fine denier natural rubber fibers described herein, even if in some instances they can be used interchangeably in certain applications. Spandex are made up of numerous polymer strands, whereas the invention described herein is one long continuous filament. Spandex is composed of two types of segments: long, amorphous segments and short, rigid segments. In their natural state, the amorphous segments have a random molecular structure. They intermingle and make the fibers soft. Some of the rigid portions of the polymers bond with each other and give the fiber structure. When a force is applied to stretch the fibers, the bonds between the rigid sections are broken, and the amorphous segments straighten out. This makes the amorphous segments longer, thereby increasing the length of the fiber. When the fiber is stretched to its maximum length, the rigid segments again bond with each other. The amorphous segments remain in an elongated state. This makes the fiber stiffer and stronger. These properties alone cannot be duplicated when producing fine denier natural rubber filaments of this invention which are extruded as long monofilaments and not consisting of two different segments.
[00366] Other drawbacks of spandex include: 1) heat sensitivity. Melting temperature of spandex is in the range of 175-178°C (from a solid to a liquid). At high temperatures the fibers can break down and lose their elasticity, and that is one reason spandex clothing should be washed in cold water and dried on low heat settings; 2) Sensitivity to ultraviolet radiation causing fibers to again degrade or lose their stretch over time. Spandex clothing should be stored away from direct sunlight; 3) Sensitive to chemicals like chlorine and certain oils, causing it to lose stretch and weaken; and 4) Pilling. Due to friction and abrasion, spandex fibres can pill (small balls on the surface of clothes).
[00367] In contrast, natural rubber is very thermostable. Natural rubber begins to melt at high temperatures, aboutl80 °C (356 °F). And once it is processed and vulcanized, it does not melt (from a solid to a liquid), which is a unique property of natural rubber and natural rubber products. At super high temperatures above 199°C (390°F) and depending on the vulcanizing agent and other fillers in the formulation, it may start to break down (e.g., burning rubber). Hence, fine denier natural rubber filaments have improved high heat, thermoset properties and applications that allow for high heat processing or finishing such as textile production. For example, elasticized fabrics like denim and cotton are excellent applications for natural rubber fibers.
[00368] Hence, fine denier natural rubber filaments can withstand high heat including higher heating setting temperatures and in textile production, e.g., high heat thermoset temperatures during finishing to control shrinkage and other properties of elastic yarns that make elastic fabrics or textiles. For those textile applications or any application requiring high heat, the fine natural rubber filaments of the invention are an excellent option.
[00369] Figure 20 shows a cone of about 200g of uncovered 200D natural rubber fibers/filaments made by the methods described herein. Filaments are individually extruded or spun and then grouped together side by side to form a ribbon, e.g., 40 filaments are common.
[00370] In one embodiment, the filaments of FIG. 20 can be used to make any of natural or synthetic (e.g., polyester) yarns made from 200 Denier (or 150 count) using a conventional ring-spinning or air-jet spinning process or similar methods. This is one embodiment of the invention, but one skilled in the art (e.g., rubber thread manufacturers) can cover the filaments with other natural and synthetic fibres including cotton, wool, bamboo etc. to maintain or improve certain textiles while providing a more bio-based and plant-based option for sustainability and biodegradability.
SPINNING
[00371] Spinning is the process of producing yarns. Yams made with spandex/lycra are composed of a plurality of spandex fibre (aka plies) which when they break due to abrasion, laundering, use (friction), normal wear and tear etc. they become easily tangled and the threads over time clump, causing surface imperfections on clothing called pilings or bubbling. Synthetic fabrics are more likely to pill than natural fabrics. Materials including but not limited fabrics and fibres made from or include polyester, acrylic, nylon, rayon, and spandex.
[00372] Spun yams or yarns made from short fibres (aka staple fibres) produce: i) a dull or a yarn with no luster and fuzzy look; ii) linting; iii) more absorbent; iv) pill; and v) complex manufacturing process.
[00373] Advantages of yams made with natural rubber filaments compared to stable fibre yarns are: i) natural rubber filaments are smooth, continuous, even and slippery to the touch and are not as textured; ii) does not require twisting or false twisting to impart strength and durability; iii) excellent durability and strength; iv) optionality to twist to control the fibers, modify their luster and create texture, and/or reduce the tenacity of the yarn and make the yam leaner (i.e. have a smaller diameter); v) chop or cut to a suitable length to produce staple fibres and then spun alone or blended with other natural or synthetic fibres in to yam; vi) do not lint or pill; vii) more pliable; and vi) easier manufacturing process.
[00374] Natural rubber filaments such as the natural rubber filaments made from PENR have longer length (or higher aspect ratio - length greater than its diameter or width) and provide filament with increased strength and durability and resistant to wear and tear, which translates into the ability to resist deformation or creep under loads and higher fatigue endurance with minimal compression. The higher aspect ratio of natural rubber can improve strength and resilience of products.
[00375] Despite the long felt need for more natural products, Applicant is the first to describe al90 denier (150-160 count) natural rubber filament and methods of making it. Despite that most skilled in the art assumed that due to its properties a fine denier natural rubber fiber was not possible, Applicants show for the first time that it is and that the invention overcomes some of the drawbacks of fine synthetic fibres like spandex including thermostability, addition of UV absorbents and/or UV stabilizers in the formulation, resistance to various chemicals and oils depending on the formulations, and not likely to pill like synthetic materials. These properties make fine denier natural rubber filaments an exceptional substitute for spandex in most applications, but for other applications as well.
Example 9: ElastomeRic Natural rubber fibre/filament formulations having 70-80% natural rubber content
[00376] Commercially available natural rubber fibers have about 80% or more natural rubber composition. The invention for the first time demonstrates that natural rubber fibers can be produced with less than 80% natural rubber composition and produce a fiber that has the same physical properties as that of fibers with 80% or more described herein including but not limited to comparable elongation, tensile strength, and modulus.
[00377] Table 19 A-C describe formulations of a natural rubber filament with less than 80% natural rubber content. In one embodiment, any of the ingredients in Tables 18 A-C, and/or equivalents thereof, can be modified and thereby change the total natural rubber content of the filament. In one embodiment, the titanium dioxide dispersion or equivalents thereof can be changed to modify the natural rubber content. In one embodiment, the Dixie Clay or equivalents thereof can be changed to correspondingly change the natural rubber content. One skilled in the art with the formulas provided in Table 18 will know how to offset and vary the below ingredient concentrations to provide for a natural rubber fibre with less or more than 80% natural rubber content if desired.
[00378] Alternatively, the natural rubber latex contents in Tables 18 can be a mixture of pre-vulcanized latex and unvulcanized latex to reduce dye swell during the extrusion process and obtain a filament with more consistent diameter measurements throughout the filament. For example, ratios of vulcanized and unvulcanized latex in ratios of 10:90, 20:80, 30:70, 40:60, 50:50, 60:40, 70:30, 80:20, 90: 10 and proportionate ratios in between. In one embodiment, 30% to 80% prevulcanized latex mixed with unvulcanized latex will reduce dye swell and help stabilize the filament and improve physical properties and performance.
Tables 19 A-C: NATURAL RUBBER LATEX fibre /FILAMENT formulation with about 70-85% natural rubber content
TABLE 19 A:
Figure imgf000093_0001
Figure imgf000094_0001
TABLE 19B:
Figure imgf000094_0002
TABLE 19C:
Figure imgf000095_0001
[00379] The above variations are embodiments of the invention, however, one skilled in the art will appreciate that variations of these formulations for any application may be necessary without deviating from the principles of the invention. [00380] Dixie Clay from a nominal 10% to 20% to a maximum of 25%, cured and tested for physical properties and processing performance. Parts by Weight is not the same calculation as percentage and the dispersions loading will need to be calculated accordingly. All the testing performed by Applicant indicates a percentage maximum of 25% before physical performance drops significantly. How you calculate ingredient loadings will need to be considered prior to reaching the maximum loading levels. If the stiffness (modulus) becomes too high, there are several ways to adjust by either lowering the PBW loading or by using a mineral oil plasticizer to soften the thread. Adjustments to sulfur should be done prior to the use of a plasticizer as this will have a more profound effect on the physical stiffness.
[00381] In addition to increasing the use of white fillers, an adjustment to the use of TiO2 may be done as well to further decrease the loading of NR latex. While Zinc Oxide is also considered a filler, the extra use is often not recommended as an offset to NR latex and has a very high unit density and will affect cure.
Biodegradability
[00382] In alternative embodiments, natural rubber filaments as provided herein are biodegradable. To determine the biodegradability of the natural rubber filaments, a ribbon consisting of 40 filaments (“40 ends”) was provided to an independent lab specializing in biodegradability studies. Each test specimen was weighed prior to burial. The test samples were moistened and then buried separately in an experimental container with microbially active soil (test soil) and incubated in standard indoor conditions. The microbially active soil was endured by the degradation of the control material that was 100% cotton sample with 100% mass loss. The test samples were removed and cleaned after 3 months and 9 months. The degradability of the test items was determined by the mass loss in aerobic biodegradation and compared to 100% mass loss of a 100% cotton control sample. All testing was performed independently by Hohenstein Institute America, a part of Hohenstein Laboratories, including ecotoxicological testing was performed using cress test (OECD 208:206), acute toxicity earthworm test (OECD 207). Hohenstein's method is based on international standards that determine the decomposition and degradation behavior of materials. [00383] To determine weight loss in a burial of microbially active soil. The difference in mass between and after excavation was calculated for each sample and compared. Variations in biological soil activity between the experimental containers was accounted for by means of standard deviation (%) of mass loss.
[00384] Table 20 is the result of an independent biodegradability study by Hohenstein of a ribbon with 40 ends or 40 filaments (not separated) showed that about 3-4% mass loss was degraded by 3 months, about 25% mass loss was observed at 9 months, and about 43% mass loss was observed at 12 months. In view of the 3, 9 and 12-month test results, it is expected that 90% or more mass loss will be reached after a total of about 24 months. All ecotoxicological tests have been passed.
[00385] This data is specific to 40 end ribbon of natural rubber, and not for single fine natural rubber monofilament. One skilled in the art would fully predict that a single filament of about 120, 130, 140, 150 or 160 count natural rubber filament would biodegrade under the same test conditions even faster. Thus, certain claims of biodegradability can be made for Applicant’s natural rubber filaments.
Table 20: Biodegradability of Natural Rubber Filaments
Figure imgf000097_0001
Example 10: Elasticized fabric production with fine natural rubber fiber [00386] Elasticized fabrics are used for a wide range of applications including sportswear apparel, fashion apparel (jeans etc.), intimate apparel (under garments etc.), socks, high-performance materials, swimwear and the like. However, most of the elasticized fibers, threads and/or filaments or their covered yarns are synthetic (not natural, not plant-based, or bio-based) like spandex, elastane, LYCRA, or equivalents thereof made from polyurethane or polyolefin materials.
[00387] Applicant has produced for the first time a light-weight elasticized denim as described in Table 20. The denim is 96% cotton and 4% natural rubber filaments, making it 100% natural product denim that should be biodegradable in view of the biodegradability of the natural rubber filaments in Example. 9, Table 19, and the same study using 100% cotton as a control that had 100% mass loss by 3 months.
Table 21: 10.75 oz Elasticized Denim
Figure imgf000098_0001
[00388] Publication W02020084359 (“Candiani”) comprises a denim fabric cotton at a weight percentage of at least 50% and an elastic natural rubber fiber of polyisoprene 1 ,4-cis elastic yam with natural rubber content higher than 80%. The embodiments herein are distinguished from Candiani since fine natural rubber filaments were not, and still not, available at the time of filing of the Candiani.
Applicant is the first to describe fine natural rubber filament compositions, formulations, and methods for makingl20-160 count or 317 - 178 denier filaments. [00389] In fact, Candiani even teaches away from the present invention by stating: Lower linear mass density elastic natural rubber threads have been recently proposed, but they are likely to break when used in the abovementioned spinning techniques, so elasticised yams comprising natural rubber are very hard and/or uneconomical to manufacture. In any case, even if the elasticized yarn production rate is decreased to prevent the natural rubber elastic thread from breaking, the elastic thread will most likely break when using the elasticised yarn to manufacture an elasticised fabric, in particular a denim type elasticised fabric, which is therefore in turn very hard and/or uneconomical to make. (See paragraph 0007 of W020200843590).
[00390] Candiani describes a traditional ring spinning technology for making yarns with different draft, which is just the ratio of linear speeds of the front rollers and delivery rollers which inserts the twist, to make the elasticized yarn. But controlling the draft with the front roller is not novel but ordinary depending on the fibre type. One skill in the art understands that the higher the draft, the more the fibers are attenuated, and the finer the fiber; but too much draft can cause the yarn to break and become weak.
[00391] Candiani describes an “an elastic thread having a linear mass density set between 50 dtex [45 denier] and 1000 dtex [900 denier].” However, nothing but less than 110 count or 120 count (or about 377 or 317 Denier) natural rubber fiber is even commercially available. That is, until the 150-160 count (or 203 to 178 Denier) fibres/filaments of the present invention.
[00392] Candiani also describes a natural rubber filament that has “polyisoprene 1,4-cis content larger than 80%”. The embodiments of the invention, also provide for the first time fine natural rubber filaments with polyisoprene 1,4-cis (or more commonly cis 1, 4 polyisoprene) content greater than 70% or less than 80% natural rubber, as well as filaments greater than 80% cis 1, 4 polyisoprene (Table 18). The denim by Candiani is a heavy weight denim greater than lOoz, or 1 loz, or 12 oz, or 13 oz or more, because the only filaments available are a 110 (377D) or 120 count (317D), and not fine filament as the invention (150 - 160 count or about 180-200D). This may be due to using a bigger in diameter fibre/filament of Candiani whichrequires more cotton or other natural fiber to cover the filament completely (prevent grinning or exposed rubber), and thus the required drafting of VI, V2 and V3 as described in Candiani FIG.1. The extra drafting adds more to the total weight of the denim. Using more cotton fibres to natural rubber also changes the performance of the fabric.
[00393] In summary, the fine natural rubber filaments provided herein provides for the first-time production of elasticized yarns and fabrics that have not been possible because existing commercial natural rubber filaments are simply too thick or not sufficiently fine, and therefore the fabrics and garments too heavy for at least denim apparel applications.
[00394] The invention of this application has been described above both generically and about specific embodiments. It will be apparent to those skilled in the art that various modifications and variations can be made in the embodiments without departing from the scope of the disclosure. Thus, it is intended that the embodiments cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents. [00395] A number of embodiments of the invention have been described.
Nevertheless, it can be understood that various modifications may be made without departing from the spirit and scope of the invention. Accordingly, other embodiments are within the scope of the following claims.

Claims

WHAT IS CLAIMED IS:
1. A rubber filament comprising natural rubber that is between about 120 to 160 count or between 317 to 178 denier.
2. A rubber filament comprising natural rubber comprising less than 80% natural rubber or content.
3. A rubber filament comprising natural rubber comprising less than 75% natural rubber content.
4. A rubber filament comprising natural rubber as of claims 1-3 wherein the natural rubber comprises cis- 1 , 4 polyisoprene.
5. The rubber filament of claim 1-4, wherein the filament is made from purified natural rubber latex that is free of more than 90% of non-rubber content.
6. The rubber filament of claim 1-5, wherein the filament is made from purified natural rubber latex that is free of 90% of proteins.
7. The rubber filament of claim 1-6, wherein the filament is made from purified natural rubber latex that has reduced levels of latex allergenic proteins.
8. The rubber filament of claim 1-7, wherein the filament is made from purified natural rubber latex that has reduced levels of latex proteins.
9. The rubber filament of claim 1- 8, wherein the filament diameter is equal to or less than 0.2 mm.
10. The rubber filament of claim 1- 9, wherein n the filament is thermostable.
11. The rubber filament of claim 1- 10, wherein n the filament is thermostable at high temperatures above 180C.
12. The rubber filament of claim 1- 11, wherein the filament is heat resistant.
13. The rubber filament of claim 1-12, wherein the filament is biodegradable.
14. A method for making a rubber filament as of claims 1-13, comprising any method of extruding the filament from a purified natural rubber latex substantially free of non-rubber content.
15. A method for making a rubber filament as of claims 1-14, comprising extruding or electrospinning the filament from a purified natural rubber latex substantially free of latex proteins.
16. A method for making a rubber filament as of claims 1-15, comprising a filament made from 10% to 90% prevulcanized natural rubber latex.
17. A method for making an elasticized yarn from any of the rubber filaments as of claims 1-16 comprising ring-spinning, rotor-spinning, twistless spinning, wrapspinning, core-spinning and/or air-jet spinning.
18. The method for making an elasticized yarn from any of the rubber filaments as of claims 1-17, wherein the yarn comprises cotton and/or other natural fibre at a weight percentage of at least 20%.
19. The method for making an elasticized yarn as of clams 17-18, wherein the yarn is thermostable.
20. The method for making an elasticized yarn 17-19, wherein the yarn is heat resistant.
21. The method for making an elasticized yarn 17-20, wherein the yarn is biodegradable.
22. The method of using any of the yarns of claims 17-20 in woven and knitted textiles.
23. The method according to any of claims 1-21, wherein the rubber is obtained from the group consisting of Hevea Brasiliensis, Hevea Guianensis, Hevea Benthamiana, Parthenium argentatum (Guayule) and Taraxacum koksaghyz.
24. A medical textile, an automotive textile, a geotextiles, a protective textile, a sportswear, or a composite comprising an elasticized yarn or rubber filament of any of the preceding claims.
PCT/US2023/027738 2022-07-14 2023-07-14 Fine denier rubber filaments comprising natural rubber and methods for making them WO2024015553A1 (en)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20010051551A1 (en) * 2000-05-01 2001-12-13 Kiyoto Maruoka Vulcanized thread rubber composition and golf ball using the same
WO2020084359A1 (en) * 2018-10-25 2020-04-30 Candiani S.P.A. A method for making an elasticised yarn and fabric manufactured from said yarn
WO2020084361A1 (en) * 2018-10-25 2020-04-30 Candiani S.P.A. Cotton-based elasticised yarns to make environment-friendly elasticised fabrics
WO2021183609A1 (en) * 2020-03-11 2021-09-16 The Lycra Company Llc Elastic fiber, composite yarns and fabrics with anti-slippage performance
WO2023046978A1 (en) * 2021-09-27 2023-03-30 Calik Denim Tekstil San. Ve Tic. A.S. Filamentary core, elastic composite yarn comprising the filamentary core, fabric comprising the filamentary core or the elastic composite yarn and method for manufacturing the filamentary core or the elastic composite yarn

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20010051551A1 (en) * 2000-05-01 2001-12-13 Kiyoto Maruoka Vulcanized thread rubber composition and golf ball using the same
WO2020084359A1 (en) * 2018-10-25 2020-04-30 Candiani S.P.A. A method for making an elasticised yarn and fabric manufactured from said yarn
WO2020084361A1 (en) * 2018-10-25 2020-04-30 Candiani S.P.A. Cotton-based elasticised yarns to make environment-friendly elasticised fabrics
WO2021183609A1 (en) * 2020-03-11 2021-09-16 The Lycra Company Llc Elastic fiber, composite yarns and fabrics with anti-slippage performance
WO2023046978A1 (en) * 2021-09-27 2023-03-30 Calik Denim Tekstil San. Ve Tic. A.S. Filamentary core, elastic composite yarn comprising the filamentary core, fabric comprising the filamentary core or the elastic composite yarn and method for manufacturing the filamentary core or the elastic composite yarn

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