CN111225998B

CN111225998B - High-bearing-capacity nylon staple fiber with additive, blended yarn and fabric thereof

Info

Publication number: CN111225998B
Application number: CN201880067935.8A
Authority: CN
Inventors: 道格拉斯·布鲁姆; 艾伦·莫蒂默
Original assignee: Invista North America LLC
Current assignee: Invista North America LLC
Priority date: 2017-10-20
Filing date: 2018-10-18
Publication date: 2023-01-24
Anticipated expiration: 2038-10-18
Also published as: MX2020003277A; EP3697953B1; JP7242664B2; US20200283933A1; BR112020007709A2; EP3697953A1; KR20200068656A; CN111225998A; JP2021500483A; WO2019079584A1

Abstract

The present invention provides nylon staple fibers with additives that exhibit a breaking strength greater than 6.5g/den and yarns, fabrics, and other articles made from the fibers. Also provided is a process for producing the nylon staple fiber with additives.

Description

High load bearing capacity nylon staple fibers with additives, and blended yarns and fabrics thereof

This patent application claims the benefit of priority from U.S. provisional application serial No. 62/575091, filed on 20/10/2017, the teachings of which are incorporated herein by reference in their entirety.

Technical Field

The present invention relates to high load nylon staple fibers containing additives, a process for producing the high load nylon staple fibers containing additives, and the use of the high load nylon staple fibers containing additives in blended yarns, fabrics and other articles.

Background

Nylon has been manufactured and used commercially for many years. The first nylon fiber was nylon 6,6, poly (hexamethylene adipamide). Nylon 6,6 fiber is still manufactured and is used commercially as the primary nylon fiber. Numerous other nylon fibers, especially nylon 6 fibers made from caprolactam, have also been made and used commercially. Nylon fibers are used in yarns for textile fabrics and for other purposes. For textile fabrics, there are basically two main yarn classes, namely continuous filament yarns and yarns made of staple fibers (i.e. cut fibers).

Nylon staple fibers are conventionally made by: melt spinning a nylon polymer into filaments; collecting a very large amount of these filaments into a tow; subjecting the tow to a drawing operation; and then converting the tow into staple fibers (e.g., in a staple cutter). Tow typically contains thousands of filaments and is typically on the order of hundreds of thousands (or more) in total denier. The drawing operation involves conveying the tow between a set of feed rolls and a set of draw rolls (operating at a higher speed than the feed rolls) to increase the orientation of the nylon polymer in the filaments. Drawing and annealing operations are typically combined to increase the degree of nylon crystallinity in the tow filaments prior to converting the tow into staple fibers.

One of the advantages of nylon staple fibers is that they are easy to blend, especially with natural fibers such as cotton (commonly referred to as staple fibers) and/or with other synthetic fibers, to achieve the advantages that such blends can produce. Nylon staple fibers have been used for many years in a particularly desirable form for blending with cotton, especially to improve the durability and economics of fabrics made from yarns comprising blends of cotton and nylon. This is because such nylon staple fibers have relatively high load-bearing strength, as described in Hebeler, U.S. patent nos. 3,044,250;3,188,790;3,321,448; and 3,459,845, the disclosures of which are hereby incorporated by reference in their entirety. The load bearing capacity of nylon staple fibers is conveniently measured as the strength at 7% elongation (T) as explained by Hebeler ₇ ) And T is ₇ Parameters have long been recognized as standard metrics and are easily read on Instron machines.

The Hebeler process for making nylon staple fibers involves the nylon spinning, tow formation, drawing and converting operations described above. The Hebeler process for making nylon staple fibers is then modified by modifying the nature of the strand drawing operation and by adding a specific type of annealing (or high temperature treatment) and subsequent cooling steps to the overall process. For example, thompson in U.S. patent nos. 5,093,195 and 5,011,645 discloses nylon staple fiber preparation in which a nylon 6,6 polymer, for example, having a formic acid Relative Viscosity (RV) of 55, is spun into filaments, which are then stretched, annealed, cooled and cut into staple fibers having a tenacity T at break of about 6.8-6.9, a denier per filament of about 2.44 and a load-bearing capacity T7 of about 2.4 to 3.2. Such nylon staple fibers are also disclosed in Thompson patents as being blended with cotton and forming yarns having improved yarn strength. (these Thompson patents are all incorporated herein by reference in their entirety).

Nylon staple fibers prepared according to the Thompson technique have been blended into NYCO yarns (typically at a 50: 50 nylon/cotton ratio) which are used to prepare NYCO fabrics. Such NYCO fabrics, such as woven fabrics, are useful in military training gear and apparel. While such fabrics have proven widely suitable for military or other robust apparel uses, military authorities, for example, are continually seeking improved fabrics that may be lightweight, low cost, and/or more comfortable, yet are highly durable or even have improved durability.

PCT/US2015/055333 discloses high strength or load bearing nylon yarns having a break strength greater than 7.5g/den and/or a strength at 10% elongation greater than 4.0g/den, as well as yarns, fabrics, and articles and methods for their production.

It has been shown that there is a desire and benefit to add pigments such as carbon black to fibers, particularly in military apparel. See, for example, U.S. patent No. 5,830,572, U.S. patent No. 7,008,694, and U.S. patent No. 7,320,766.

Furthermore, denim and canvas fabrics, especially dark denim, and especially black denim, have become popular in the market, but are known in the industry to have problems with fading or color fastness. For example, in the case of black denim, the coloration fades rapidly after repeated laundering/abrasion. It is also known that the addition of nylon as a blend with cotton or cellulose fibers significantly improves the durability of the yarn and resulting fabric by improving abrasion resistance. The black dye used to dye black denim fabric only dyes nylon fibers and is not as dark or permanent on nylon fibers as on cotton fibers.

However, any blend of nylon staple fibers with cotton or cellulose fibers requires high strength/high modulus.

Additives such as pigments added to polymers prior to melt spinning of fibers have historically reduced fiber physical properties. For example, organic pigments tend to crosslink nylon, change the viscosity of nylon, form spherulites that weaken the fiber, and result in increased tensile strength and filament breakage. The more pigment added, the greater the loss of strength. These reduced fiber characteristics have prevented or limited the blending of colored nylon staple fibers with cellulosic fibers due to the resulting low yarn strength and low fabric strength problems.

For example, duPont produced colored nylon staple fibers in the middle and late 90 s of the 20 th century for automotive upholstery. The resulting nylon staple fiber product has a tenacity at break of less than 5.5 grams per denier. The only end use identified at that time was spinning of the yarn in 100% form for automotive/home furnishings.

U.S. Pat. No. 5,290,850 discloses an improved method of melt spinning colored hexamethylene adipamide fibers from a melt blend of a polymer and a colored pigment, wherein the polymer is a randomly copolymerized polyamide or block polymer having two different difunctional recurring amide forming moieties in addition to those difunctional recurring amide forming moieties that form hexamethylene exhibiting a tenacity of greater than 7.5 grams per denier.

There is a need for additional high load-bearing nylon staple fibers with additives for use in fabrics and other articles.

Disclosure of Invention

In general, the addition of any inorganic or organic pigments or additives to the polymer during the melt spinning process reduces the resulting fiber strength. The loss of fiber strength translates into lower strength of the yarn and resulting fabric. The inventors herein have unexpectedly discovered that adding an additive to a nylon polymer prior to fiber formation and stretching the fiber under a steam assisted/annealing process results in a high strength/high modulus fiber containing the additive.

Accordingly, one aspect of the present invention relates to nylon staple fibers comprising a nylon polymer and an additive. The nylon staple fibers with the additives of the present invention exhibit a break strength greater than 6.5g/den. In one non-limiting embodiment, the nylon staple fibers exhibit a strength greater than 3.0g/den at 10% elongation. Non-limiting examples of additives that may be included in these fibers are pigments and additives that are included for fire or Flame Retardancy (FR) and/or Ultraviolet (UV) protection.

Another aspect of the invention relates to a yarn spun from nylon staple fibers. In one non-limiting aspect, the yarn further comprises at least one companion staple fiber. In one non-limiting embodiment, the nylon content of the yarn is greater than 5%. In one non-limiting embodiment, the yarn has a nylon content greater than 30%. In one non-limiting embodiment, the nylon content of the yarn is greater than 50%. Such yarns can be made into fabrics and other articles that are advantageously lightweight, comfortable, relatively low cost, and durable, and thus are particularly suitable for or as, for example, military apparel, such as training gear or other apparel for robust and durable use.

Another aspect of the present invention relates to an article of manufacture, at least a portion of which comprises the nylon staple fibers or yarns of the present invention.

In one non-limiting embodiment, the article is a fabric.

In one non-limiting embodiment, the fabric is dyed a solid color and/or exhibits a uniform dark hue.

In one non-limiting embodiment, the fabric exhibits improved ultraviolet light fastness (UV light fastness) compared to a recent comparison fabric lacking such pigmented or additive-containing components.

In one non-limiting embodiment, the fabric exhibits improved dye wash fastness (dye wash fastness) as compared to a recent comparative fabric lacking such pigmented or additive-containing components.

In one non-limiting embodiment, the fabric is a camouflage print. The fabric is typically constructed by using colored synthetic fibers, such as polyamide 6,6 or nylon 6,6, but the fabric may also be a greige cloth or a non-colored fabric. However, in the case of fibers that are colored, printing can still occur on top of the colored fabric.

In one non-limiting embodiment, the fabric exhibits NIR (near infrared) reflectance in the range of 600-900nm and/or lower and flattened SWIR (short wave infrared) reflectance in the range of 900-2500 nm. In addition, the fabric increases the separation of Infrared (IR) reflectance curves between the various colors used in printing the fabric in the SWIR spectrum and provides further disruption of night vision goggle surveillance and improved camouflage.

In one non-limiting embodiment, the fabric has improved flame retardant properties.

In one non-limiting embodiment, the fabric exhibits improved arc rating compared to a recent comparative fabric lacking such pigmented or additive-containing components.

In one non-limiting embodiment, the article is a denim fabric. In one non-limiting embodiment, the denim fabric is overprinted in a color similar to the pigment contained in the nylon staple fibers. Furthermore, when the fibers are black and the fabric is printed in a dark color, a more uniformly dyed product is obtained, as the black fibers will serve to minimize or eliminate the appearance of white fibers through the fabric.

In another non-limiting embodiment, the article is a nonwoven fabric composite. End uses for such composites include, but are not limited to, industrial (felt/backing/filtration/insulation), apparel (including lining fabrics), footwear, bag/bag rigid gears, durable and semi-durable (disposable or semi-disposable) garments or PPEs, including FR (chemically treated or combined with inherent FR fiber technology), biochemical or other specialty protective apparel.

Another aspect of the invention relates to a method of producing high strength or load bearing colored nylon staple fibers. The process of the present invention comprises melt spinning a nylon polymer with pigments into filaments, then uniformly quenching the filaments, and forming a tow from a plurality of the quenched filaments. The tow is then subjected to drawing in the presence of steam. The drawn tow is then annealed and the resulting drawn and annealed tow is converted into staple fibers. In one non-limiting embodiment, the annealing is performed under tension. The nylon staple fibers produced according to this process have a breaking strength greater than 6.5g/den. In one non-limiting embodiment, the nylon staple fiber made according to this process has a strength of greater than 3.0g/den at 10% elongation.

Detailed Description

The present disclosure provides high strength or load bearing nylon staple fibers with additives that exhibit a break strength greater than 6.5g/den and/or a strength at 10% elongation greater than 3.0g/den, yarns, fabrics, and other articles made from these fibers and methods for their production.

Non-limiting examples of additives included in nylon staple fibers are pigments, additives to provide uv protection, and additives for FR resistance.

In one non-limiting embodiment, the additive is a pigment present in an amount from about 10 parts per million to about 50,000 parts per million. In one non-limiting embodiment, the pigment is carbon black. Further examples of suitable pigments are: ultramarine violet, a silicate of sodium and aluminum containing sulfur; hanzi Zi, baCuSi ₂ O ₆ (ii) a Cobalt violet, cobalt orthophosphate; manganese violet, NH ₄ MnP ₂ O ₇ (ii) a Ultramarine pigment, na _8-10 Al ₆ Si ₆ O ₂₄ S _2-4 (ii) a Persian blue, (Na, ca) ₈ (AlSiO ₄ ) ₆ (S，SO ₄ ，Cl) _1-2 (ii) a Cobalt blue, cobalt (II) stannate; egyptian blue, (CaCuSi) ₄ O ₁₀ ) (ii) a Hanlan, baCuSi ₄ O ₁₀ (ii) a Azurite, (Cu) ₃ (CO ₃ ) ₂ (OH ₂ ) ); prussian blue, iron ferrocyanide; yttrium indium manganese blue, (YLn) _1-x Mn _x O ₃ ) (ii) a Cadmium Green, cdS and Cr ₂ O ₃ A mixture of (a); chromium green, chromium oxide; dark emerald green, hydrated chromium oxide; rimnan green, coZnO ₂ (ii) a Lime (Cu) ₂ CO ₃ (OH) ₂ ) (ii) a Paris Green, cu (C) ₂ H ₂ O ₂ ) _2.3 Cu(AsO ₂ ) ₂ ) (ii) a Schiller green, cuHAsO ₃ (ii) a Verdigris, which is typically copper acetate and/or malachite; flomana green, (K [ (Al, fe) ^III )，(Fe ^II ，Mg](AlSi ₃ ，Si ₄ )O ₁₀ (OH) ₂ ) (ii) a Orpimentum, (As) ₂ S ₃ ) (ii) a Primrose yellow (BiVO) ₄ ) (ii) a Cadmium yellow, cdS; chrome yellow, pbCrO ₄ (ii) a Cobalt yellow, (K) ₃ Co(NO ₂ ) ₆ ) (ii) a Yellow earthy (Fe) ₂ O ₃ .H ₂ O); titanium yellow; color gold, snS ₂ (ii) a Whelk red, cadmium sulfoselenide; chromium orange, (PbCrO) ₄ + PbO); realgar, AS ₄ S ₄ (ii) a Cadmium red, cdSe; indian red; haematitum Red, fe ₂ O ₃ (ii) a Dark brown; vermilion, hgS; brown, fe ₂ O ₃ +MnO ₂ +nH ₂ O+Si+AlO ₃ (ii) a Ochre is generated; ivory black; rattan black; lamp black; ma Si Black, fe ₃ O ₄ (ii) a Manganese dioxide; titanium black, ti ₂ O ₃ (ii) a Antimony white, sb ₂ O ₃ (ii) a Barium sulfate; lithopone, baSO ₄ ZnS; pure white lead, ((PbCO) ₃ ) ₂ ·Pb(OH) ₂ ) (ii) a Titanium dioxide, tiO ₂ (ii) a And zinc oxide, znO.

The present disclosure also provides nonwoven fabric composites comprising high strength fibers and cellulosic or recycled synthetic or natural fibers.

As used herein, the terms "durable" and "durability" refer to fabrics that tend to be characterized as having suitably high grab and tear strength and abrasion resistance for the intended end use of such fabrics, and maintaining such desired properties for a suitable length of time after fabric use has begun.

As used herein, the term "blend" or "blended" with respect to a spun yarn refers to a mixture of at least two types of fibers, wherein the mixture is formed in a manner such that the individual fibers of each type of fiber are substantially completely mixed with the individual fibers of the other type to provide a substantially homogeneous mixture of fibers having sufficient entanglement to maintain their integrity during further processing and use.

As used herein, cotton count refers to a yarn count system based on a length of 840 yards, and wherein the yarn count is equal to the number of 840 yards of hank needed to weigh 1 pound.

All numerical values set forth herein are understood to be modified by the term "about".

Some embodiments are based on the preparation of improved nylon staple fibers with additives having certain specified properties; and is based on the subsequent preparation of yarns, and fabrics woven from such yarns, wherein these improved nylon staple fibers with additives are blended with at least one other fiber. Other fibers may include cellulose, such as cotton; modified cellulose such as fire-retardant (FR) -treated cellulose; a polyester; artificial silk; animal fibers such as wool; FR polyester; FR nylon; FR rayon; meta-aramid fiber; para-aramid fiber; modifying acrylic fibers; a phenolic resin; melamine; polyvinyl chloride; antistatic fiber; PBO (polymer of 1, 4-benzenedicarboxylic acid with 4, 6-diamino-1, 3-benzenediol dihydrochloride); PBI (polybenzimidazole); and combinations thereof. The nylon staple fibers of some embodiments can provide an increase in strength and/or abrasion resistance to the yarn and fabric. This is particularly true for combinations with relatively weak fibers such as cotton and wool.

Specific characteristics of the nylon staple fibers with additives made and used herein include fiber denier, fiber strength, and fiber load-bearing capacity, defined as fiber strength at 7% and 10% elongation.

The realization of desirable nylon staple fibers with additive materials herein is based on the use of nylon polymer filaments and tows in staple fiber manufacture having certain selected properties and processed using certain selected processing operations and conditions. In particular, the inventors herein have discovered that during the production of nylon staple fibers with additives, the introduction of steam between the feed module and the draw module and/or tension during annealing significantly inhibits or prevents the strength reduction associated with the addition of such fiber additives. In one non-limiting embodiment of the invention, steam is introduced into the process by adding a steam chamber between the feed module and the stretch module, as this allows for the removal of excess water prior to annealing. Without being bound by any particular theory, it is believed that the steam chamber adds sufficient heat/steam to reduce the stretching force of the nylon and help to confine the stretching to the steam chamber rather than above or at the exit of the feed roll. The steam may be controlled by pressure.

The nylon polymer used for spinning the nylon filaments of the present invention can be produced in a conventional manner per se. Nylon polymers suitable for use in the methods and filaments of some embodiments comprise synthetic melt-spun or melt-spun polymers. Such nylon polymers may comprise predominantly aliphatic polyamide homopolymers, copolymers, and mixtures thereof, i.e., less than 85% of the amide linkages of the polymer are attached to two aromatic rings. Widely used polyamide polymers may be used according to some embodiments, such as poly (hexamethylene adipamide) which is nylon 6,6 and poly (epsilon-decanamide) which is nylon 6, as well as copolymers thereof and mixtures thereof. Other polyamide polymers that may be advantageously used are nylon 12, nylon 4,6, nylon 6, 10, nylon 6, 12, nylon 12, 12, and copolymers thereof and mixtures thereof. Examples of polyamides and copolyamides that may be used in the processes, fibers, yarns, and fabrics of some embodiments are those described in U.S. Pat. Nos. 5,077,124, 5,106,946, and 5,139,729 (all to Cofer et al) and polyamide polymer blends disclosed by Gutmann in Chemical Fibers International, pages 418-420, volume 46, month 12 1996. These publications are incorporated herein by reference.

In one non-limiting embodiment, the polymer may further comprise a monomeric salt of Sulfonated Isophthalate (SIPA) or monomeric methylpentanediamine (MPMD). In one non-limiting embodiment, the monomer is added in an amount of about 0.04% to about 4% by weight of the nylon polymer.

Nylon polymers used to prepare nylon staple fibers are conventionally prepared by reacting appropriate monomers, catalysts, antioxidants, and other additives including, but not limited to, plasticizers, delusterants, pigments, dyes, light stabilizers, heat stabilizers, antistatic agents for reducing static electricity, additives for changing dyeability, agents for changing surface tension, and the like. The polymerization is usually carried out in a continuous polymerizer or a batch autoclave. The resulting molten polymer is then typically introduced into a spin pack where it is forced through a suitable spinneret and formed into filaments, which are quenched and then formed into a tow for final processing into nylon staple fibers. As used herein, a spin pack consists of a pack cover located at the top of the pack, a spinneret plate located at the bottom of the pack, and a polymer filter holder sandwiched between the first two components. The filter holder has a central recess therein. The cover and recess in the filter holder cooperate to define an enclosed pocket in which a polymeric filter media, such as sand, is contained. Channels are provided inside the assembly to allow molten polymer supplied by a pump or extruder to flow through the assembly and ultimately through the spinneret plate. The spinneret plate has an array of fine small holes extending therethrough that deliver polymer to the lower surface of the assembly. The orifices of the holes form an array of holes on the lower surface of the spinneret plate, which surface defines the top of the quench zone. The polymer exiting the holes is in the form of filaments which are then directed downwardly through a quench zone.

The degree of polymerization carried out in a continuous polymerizer or batch autoclave can generally be quantified by means of a parameter known as the relative viscosity or RV. RV is the ratio of the viscosity of a solution of nylon polymer in formic acid solvent to the viscosity of the formic acid solvent itself. RV is considered an indirect indicator of nylon polymer molecular weight. For purposes herein, increasing the RV of a nylon polymer is considered synonymous with increasing the molecular weight of the nylon polymer.

As nylon molecular weight increases, processing of nylon becomes more difficult due to the increasing viscosity of nylon polymers. Accordingly, a continuous polymerizer or batch autoclave will typically be operated to provide a nylon polymer for final processing into staple fibers, wherein the nylon polymer has an RV value of about 60 or less.

It is known that for some purposes it may be advantageous to provide nylon polymers having a greater molecular weight, i.e. nylon polymers having RV values greater than 70-75 and up to 140 or even 190 and higher. For example, high RV nylon polymers of this type are known to have improved flex abrasion resistance and chemical degradation resistance. Accordingly, such high RV nylon polymers are particularly suitable for spinning into nylon staple fibers, which can be advantageously used to prepare papermaking felts. Procedures and equipment for preparing high RV nylon polymers and staple fibers made therefrom are disclosed in U.S. patent No. 5,236,652 to Kidder and U.S. patent No. 6,235,390 to Schwinn and West; 6,605,694;6,627,129 and 6,814,939. All of these patents are incorporated by reference herein in their entirety.

According to some embodiments, it has been found that staple fibers made from nylon polymers having RV values generally consistent with or in some cases higher than values typically obtained via polymerization in a continuous polymerizer or batch autoclave, unexpectedly exhibit increased fiber break strength and increased strength at 10% elongation when processed with additives and according to spinning, quenching, feeding, and drawing in the presence of steam and annealing procedures described herein, as compared to standard products or previously described improvements. When such nylon staple fibers with additives having improved strength are blended with one or more other fibers, such as cotton staple fibers, a textile yarn having improved strength and lower weight can be achieved. Fabrics woven from such yarns, such as NYCO fabrics, exhibit the advantages described above with respect to durability, optionally lighter weight, improved comfort and/or potentially lower cost, as well as the benefits of selected additive color, uv protection or FR resistance.

According to the staple fiber production process herein, the nylon polymer with additives melt spun through one or more spin pack spinnerets into filaments forming a tow and quenched will have RV values in the range of 45 to 100, including 55 to 100, 46 to 65, 50 to 60, and 65 to 100. Nylon polymers having such RV properties can be prepared, for example, using a polyamide concentrate melt blending procedure such as the method disclosed in the Kidder 5,236,652 patent noted above. Kidder discloses certain embodiments in which a catalyst is added to increase the Relative Viscosity (RV) of formic acid. Higher RV nylon polymers useful for melting and spinning, such as nylons having an RV of 65 to 100, can also be provided by a Solid Phase Polymerization (SPP) step in which nylon polymer flakes or particles are adjusted to increase the RV to a desired degree. Such Solid Phase Polymerization (SPP) procedures are well known and are disclosed in more detail in the aforementioned Schwinn/West patents 6,235,390, 7,008,694, 6,627,129, and 6,814,939.

A nylon polymeric material with additives having the desired RV properties as specified herein is fed into a spin pack, for example, via a twin screw melt device. In one non-limiting embodiment, the additives are added using a volumetric or gravimetric feeder. In the spin pack, the nylon polymer with additives is spun into a plurality of filaments by extrusion through one or more spinnerets. For purposes herein, the term "filament" is defined as a relatively flexible, macroscopically homogeneous body having a high aspect ratio in its cross-section perpendicular to its length. The filament cross-section can be any shape, but is typically circular. The term "fiber" is also used interchangeably herein with the term "filament".

Each individual spinneret position can contain 100 to 1950 filaments in an area as small as 9 inches by 7 inches (22.9 cm x 17.8 cm). The spin-combining machine may contain one to 96 stations, each providing a bundle of filaments that is ultimately combined into a single tow band for stretching/downstream processing with other tow bands.

After exiting the spinnerets, the molten filaments that have been extruded through each spinneret typically pass through a quench zone, where various quench conditions and configurations can be used to solidify the molten polymer filaments with additives and make them suitable for collecting together into a tow. Quenching is most often carried out by: a cooling gas (e.g., air) is passed toward, onto, with, around, and through the filament bundle that is extruded from each spinneret location within the spin pack into the quench zone.

One suitable quenching configuration is cross-flow quenching, wherein a cooling gas (such as air) is forced into the quenching zone in a direction substantially perpendicular to the direction of travel of the extruded filaments through the quenching zone. In U.S. Pat. nos. 3,022,539;3,070,839;3,336,634;5,824,248; cross-flow quench arrangements, as well as other quench configurations, are described in U.S. Pat. nos. 6,090,485, 6,881,047, and 6,926,854, the teachings of which are incorporated herein by reference in their entirety.

In one non-limiting embodiment of the staple fiber preparation process herein, extruded, additive-bearing nylon filaments used to ultimately form the desired additive-bearing nylon staple fibers are spun, quenched, and formed into a tow using positional uniformity and quenching uniformity conditions, as described in published U.S. patent applications nos. 2011/0177737 and 2011/0177738, the teachings of which are incorporated herein by reference in their entirety.

The quenched spun filaments can then be combined into one or more tows. Such tows, formed from filaments from one or more spinnerets, are then subjected to a two-stage continuous operation in which the tows are stretched and annealed in the presence of steam.

Drawing of the tow typically occurs primarily in an initial or first drawing stage or zone, wherein a tow band is passed between a set of feed rolls and a set of draw rolls (operating at higher speeds) to increase the crystalline orientation of the filaments in the tow. The extent to which the tow is drawn can be quantified by specifying the draw ratio, which is the ratio of the higher peripheral speed of the draw rolls to the lower peripheral speed of the feed rolls. The effective stretch ratio is calculated by multiplying the first stretch ratio by the second stretch ratio.

The first drawing stage or zone may include sets of feed and draw rolls and other tow guide and tensioning rolls, such as draw point holding bars (snubbing pins). The draw roll surface may be made of metal (e.g., chrome) or ceramic. It has been found that a ceramic draw roll surface is particularly advantageous in allowing the use of the relatively high draw ratios specified in connection with the staple fiber production process herein. Ceramic rollers improve the life of the roller and provide a less easily wound surface. An article appearing in the International Journal of fibers (International Fiber Journal) ("Textile and Bearing Technology for separating Rolls", zeitz et al (International Fiber Journal,17, 2002, 2.1, february 2002: "Textile and Bearing Technology for Separator Rolls", zeitz and el.)) and U.S. Pat. No. 4,794,680, which are incorporated herein by reference, also disclose the use of ceramic Rolls to improve roll life and reduce Fiber adhesion to roll surfaces.

Although the maximum drawing of the filament tow herein occurs in the initial or first drawing stage or zone, some additional drawing of the tow will typically also occur in the second or annealing and drawing stage or zone described below. The total amount of draw to which the filament bundle is subjected herein can be quantified by specifying a total effective draw ratio that takes into account the draw that occurs in both the first initial draw stage or zone and in the second zone or stage in which annealing and some additional draw is performed simultaneously.

In the process of some embodiments, the tow of nylon filaments with additives is subjected to a total effective draw ratio of from 2.3 to 5.0, including from 3.0 to 4.0. In one embodiment, where the denier per filament of the tow is generally small, the total effective draw ratio may be in the range of 3.12 to 3.40. In another embodiment, where the denier per filament of the tow is generally greater, the total effective draw ratio may be in the range of 3.5 to 4.0.

In the process herein, as described above, most of the drawing of the tow occurs in the first or initial drawing stage or zone. Specifically, 85% to 97.5%, including 92% to 97%, of the total amount of stretch imparted to the tow will occur in the first or initial stretch stage or zone. The drawing operation in the first or initial stage will generally be conducted at any temperature that the filaments have as they pass out of the quench zone of the melt spinning operation. Typically, the first stage stretching temperature will be in the range of 80 ℃ to 125 ℃.

In the present invention, steam is introduced between the feed and the draw. In one embodiment, a steam chamber is used between the feed module and the stretching module.

From the first or initial drawing stage or zone, the partially drawn tow is passed to a second annealing and drawing stage or zone where the tow is simultaneously heated and further drawn. The tow is heated to effect annealing for increasing the crystallinity of the nylon polymer of the filaments. In this second annealing and drawing stage or zone, the filaments of the tow are subjected to an annealing temperature of 145 ℃ to 205 ℃, such as 165 ℃ to 205 ℃. In one embodiment, the temperature of the filament bundle in the annealing and drawing stage may be achieved by contacting the filament bundle with a steam heated metal plate positioned between the first stage drawing and second stage drawing and annealing operations. In the present invention, annealing/oven drying under tension helps remove excess moisture obtained during steam stretching.

After the annealing and drawing stages of the process herein, the drawn and annealed tow is cooled to a temperature of less than 80 ℃, such as less than 75 ℃. Throughout the stretching, annealing, and cooling operations described herein, the tow is maintained under controlled tension and therefore not allowed to relax.

After drawing in the presence of steam and annealing/oven drying under tension, the multifilament tow is converted into staple with additives by any conventional means (e.g., using a staple cutter). The length of staple fibers with additives formed from the tow will typically be in the range of 2cm to 13cm (0.79 to 5.12 inches). For example, the staple fibers with additives can be in the range of 2cm to 12cm (0.79 to 4.72 inches), 2cm to 12.7cm (0.79 to 5.0 inches), or 5cm to 10 cm. The staple fibers with additives herein can optionally be crimped.

The high strength nylon staple fibers with additives formed according to the methods herein will generally be provided as a collection of fibers, for example as a bundle of fibers, each fiber having a denier of 1.0 to 3.0. When staple fibers having a denier per fiber of from 1.6 to 1.8 are to be produced, a total effective draw ratio of from 3.12 to 3.40, such as from 3.15 to 3.30, can be used in the process herein to provide staple fibers having a desired load-bearing capacity. When staple fibers having a denier per fiber of 2.5 to 3.0 or 2.3 to 2.7 are to be produced, then an overall effective draw ratio of 3.5 to 4.0 or 3.74 to 3.90 should be used in the process herein to provide staple fibers having the desired load-bearing capacity.

Using this method and then annealing the fiber with additive at 180 ℃ using standard annealing rolls produced a significantly higher strength fiber with additive having a strength greater than 6.5g/den.

In one non-limiting embodiment of the present invention, nylon staple fibers with additives are disclosed that have a strength of at least 3.0g/den at 10% elongation.

Fibers having the above characteristics and having the added advantages of additives in the fibers of the present invention (such as pigments, UV protectants, and FR resistance agents) can be used in lower blend ratios or spun into yarns using alternative spinning systems that significantly reduce the cost of fabric manufacture and still meet existing fabric specifications. The fibers can be used to significantly reduce yarn spinning and finished fabric costs by allowing the use of lower nylon blend levels and/or alternative spinning systems while maintaining fabric properties.

The nylon staple fibers with additives provided herein are particularly useful for blending with other fibers for various types of textile applications. Blends can be prepared, for example, with some embodiments of nylon staple fibers in combination with other synthetic fibers, such as rayon or polyester. Examples of nylon staple fiber blends herein include those made with natural cellulosic fibers such as cotton, flax, hemp, jute, and/or ramie. Suitable methods for intimately blending these fibers may include: before carding, a large amount of mechanical cotton mixing is carried out on short fibers; subjecting the staple fibers to a substantial mechanical mixing prior to and during carding; or subjecting the staple fibers to at least two stretcher (draw frame) mixing after carding and before spinning.

According to one non-limiting embodiment, the high load bearing capacity nylon staple fibers with additives herein can be blended with cotton staple fibers and spun into textile yarns. Such yarns may be spun in a conventional manner using commonly known short and long staple spinning methods, including ring spinning, air or vortex spinning, open end spinning, or friction spinning. When the yarn blend comprises cotton, the resulting textile yarn will typically have a cotton to nylon fiber weight ratio of from 10: 90 to 90: 10, including from 30: 70 to 70: 30, and typically a 50: 50 cotton to nylon weight ratio. It is well known in the art that nominal variations in fiber content, such as 52: 48, are also considered 50: 50 blends.

Nylon/cotton (NYCO) yarns of some embodiments may be used in a conventional manner to produce NYCO woven fabrics having particularly desirable characteristics for use in apparel for military or other rugged use. Thus, such yarns can be woven into 2 x 1 or 3 x 1 twill NYCO fabrics. Spun NYCO yarns and 3 x 1 twill woven fabrics containing such yarns are generally described and exemplified in U.S. patent No. 4,920,000 to Green, which is incorporated herein by reference.

Of course, NYCO woven fabrics include both warp and weft (fill) yarns. Woven fabrics of some embodiments are those having NYCO textile yarns herein woven in at least one of these directions and optionally both. In one embodiment, a fabric having particularly desirable durability and comfort herein will have yarns woven in the weft (fill) direction comprising nylon staple fibers with additives herein; and will have yarns woven in the warp direction that contain the nylon staple fibers with additives herein.

Woven fabrics of some embodiments made using yarns comprising high load nylon staple fibers with additives herein may use less nylon staple fibers than conventional NYCO fabrics while maintaining many of the desirable characteristics of such conventional NYCO fabrics. Thus, such fabrics can be made relatively lightweight and low cost, while still being advantageously durable. Alternatively, such fabrics may be made using equal or even greater amounts of the nylon staple fibers with additives herein as compared to the nylon fiber content of conventional NYCO fabrics, wherein such fabrics herein provide superior durability characteristics.

In one non-limiting embodiment, the nylon staple fibers of the present invention with pigment additives are used to produce articles such as denim fabric. At present, black dyed 100% cotton denim fabric has fading and abrasion problems after repeated laundering. Although non-pigmented high strength nylon staple fibers can be added to improve fabric durability and strength, the problem of discoloration still exists. The addition of the colored high strength nylon staple fibers of the present invention containing additives such as carbon black reduces black appearance loss and improves wear life. As will be understood by the skilled artisan upon reading this disclosure, alternative pigments for colors such as blue, green, and tan may also be used. In this non-limiting embodiment, colored fibers having 1-5 weight percent coloration, such as carbon black or denim blue, may be used in denim to reduce fabric fading problems and improve durability. The incorporation of these fibers into fabrics is particularly useful for articles dyed to a solid color and/or where improved uniformity of dyeing, such as dark shades, is desired.

In some embodiments, the denim fabric may be overprinted in a color similar to the pigment contained in nylon staple fibers. Camouflage printed fabrics may also be made from nylon staple fibers of the present invention with additives.

Such fabrics are expected to exhibit improved dye wash fastness.

Furthermore, the addition of carbon black to fibers or fabrics as a topical treatment is known to improve the concealment of uniforms/wearers when viewed through night vision goggles using Near Infrared (NIR) and Short Wave Infrared (SWIR) technologies.

Thus, in another non-limiting embodiment, colored nylon staple fibers with carbon black of the present invention in a range of from 10ppm to 1000ppm can be used to improve the concealment of an article (such as a uniform) comprising the fibers when viewed under SWIR/IR night vision goggles. In one non-limiting embodiment, incorporation of the colored nylon staple fibers of the present invention containing conventional dyes can reduce NIR reflectance in the range of 600-900nm without any pretreatment or post-treatment or use of metallized or special pigment formulations and without significantly changing the hue in the visible spectrum, thereby enhancing the camouflage damage (camouflage damage) and effect of anti-night vision surveillance.

In another non-limiting embodiment, incorporation of the colored nylon staple fibers of the present invention containing conventional dyes can reduce the Short Wave Infrared Reflectance (SWIR) in the 900-2500nm range and allow for a plateau without pretreatment or post-treatment or use of metallization or special pigment formulations required for pure and printed camouflage NYCO fabrics, and without significant change in hue in the visible spectrum, thereby enhancing camouflage damage and effectiveness of anti-night vision goggles surveillance. In another non-limiting embodiment, incorporation of the colored nylon staple fibers of the present invention comprising conventional dyes can increase the level of separation between print colors in the SWIR in the range of 900-2500nm without the need for pre-or post-treatment or the use of metallized or special pigment formulations, thereby enhancing camouflage damage and effect against night vision goggle surveillance. Such fabrics of the present invention are also expected to exhibit improved arc ratings.

In another non-limiting embodiment, incorporation of nylon staple fibers with an additive that provides uv protection or an additive that provides FR resistance into an article such as a fabric results in improved uv fastness and/or flame retardancy.

The present invention also relates to nonwoven fabric composites comprising the high strength fibers of the present invention. High strength fibers can be combined with various cellulosic or recycled synthetic or natural fiber technologies. In one embodiment, high strength fibers are combined with the recycled denim. End uses for nonwoven fabric composites include, but are not limited to, industrial (felt/backing/filtration/insulation), apparel (including lining fabrics), footwear, bag/pack rigid gear, durable and semi-durable (disposable or semi-disposable) garments or PPEs, including FR (chemically treated or combined with inherent FR fiber technology), biochemical or other professional protective apparel.

As will be understood by the skilled person upon reading this disclosure, alternative methods and apparatuses to those exemplified herein can be obtained that result in at least a portion of the yarn on the top surface or at least a portion of the yarn on the bottom surface having fibers that have a permanently modified cross-section and that are melt fused together, and the use of such alternative methods and apparatuses is encompassed by the present invention.

All patents, patent applications, test procedures, priority documents, articles, publications, manuals, and other documents cited herein are incorporated by reference in their entirety to the extent such disclosure is not inconsistent with this invention and for all jurisdictions in which such incorporation is permitted.

Test methods and examples

The following test methods and examples demonstrate the invention and its ability to be used. The invention is capable of other and different embodiments and its several details are capable of modifications in various obvious respects, all without departing from the scope and spirit of the present invention. Accordingly, the test methods and examples are to be considered as illustrative and not restrictive in nature.

Relative viscosity of Nylon Polymer

The formic acid RV of the nylon material as used herein refers to the ratio of the solution viscosity to the solvent viscosity as measured with a capillary viscometer at 25 ℃. The solvent was formic acid containing 10 wt% water. The solution was 8.4 wt% nylon polymer dissolved in solvent. The test is based on ASTM standard test method D789. Formic acid RV on the spun filaments is measured before or after drawing and may be referred to as spun fiber formic acid RV.

Instron measurement of short fibers

All Instron measurements of staple fibers herein were made on individual staple fibers, with due care to the pinching of the staple fibers, and the measurements were averaged over at least 10 fibers. Generally, at least 3 sets of measurements (10 fibers per set) are averaged together to provide a value for the measured parameter.

Fineness of filament

Denier is the linear density of a filament expressed as the weight in grams of 9000 meters of the filament. The titer can be measured on a vibrometer from Textechno, munich, germany. The titer time (10/9) is equal to decitex (dtex). The denier per filament may be determined gravimetrically according to ASTM standard test method D1577. Favimat machines with vibration-based linear density measurements, such as used in vibrometers, can also be used to determine the denier per filament or DPF of individual fibers and are comparable to ASTM D1577.

Breaking strength

The breaking strength (T) is the maximum or breaking force of the filament, expressed as force per unit cross-sectional area. Strength can be measured on an Instron model 1130, available from Instron corporation of Canton, mass, and reported as grams per denier. Filament breaking strength (and elongation at break) can be measured according to ASTM D885.

Filament Strength at 7% and 10% elongation

The strength of the filament at 7% elongation (T7) is the force applied to the filament to obtain 7% elongation divided by the filament denier. T7 can be determined according to ASTM D3822. The strength at 10% elongation can be run on a Favimat, which is comparable to ASTM D3822.

Yarn strength

The strength of the spun nylon/cotton yarn herein can be quantified via Lea product value or yarn break strength. Lea products and skein breaking strength are conventional measures of the average strength of textile yarns and can be determined according to ASTM D1578. Lea product values are reported in pounds force. The breaking strength is reported in cN/tex.

Weight of fabric

Weaving fabricThe fabric weight or basis weight of the article may be determined by: a fabric sample of known area is weighed and measured in grams/m according to the procedure of the standard test method of ASTM D3776 ² Or oz/yd ² Weight or basis weight is calculated as a unit.

Fabric gripping strength

Fabric grab strength can be measured according to ASTM D5034. Grab strength measurements were reported in pounds-force in both the warp and weft directions.

Tear strength of fabric-Elmendorf

The tear Strength of a fabric can be measured according to ASTM D1424 entitled Standard Test Method for testing Strength of Fabrics by Falling weight (Elmendorf) Apparatus for Standard Test Method for testing the tear Strength of Fabrics-polyethylene Type (Elmendorf) Apparatus. Grab strength measurements were reported in pounds-force in both warp and weft directions.

Method 61 for testing fastness to washing and ironing-AATCC

AATCC 61 was used to evaluate the colorfastness to laundering of textiles expected to resist frequent laundering. The specimens were attached to a multi-fiber sample and stainless steel balls were loaded into stainless steel cans to measure wear in parallel. The cans were then loaded into the machine and the 45 minute test was started. After washing and scalding, the specimens were dried, conditioned, and evaluated with both the gray scale of color change and the gray scale of staining. The dimensional change of the laundered and ironed fabric was also tested and applied for evaluation according to AATCC test method 135.

Light color fastness-AATCC test method 16

This test method provides the general principle and procedure currently used to determine the light fastness of textile materials. The described test options apply to a variety of textile materials and are directed to colorants, finishes and treatments applied to the textile materials.

The included test options are:

1-closed carbon arc lamp, continuous light

2-enclosed carbon arc lamps, alternating light and dark

3-xenon arc lamp, continuous light, black panel option

4-xenon arc lamp, alternating light and darkness

5-xenon arc lamp, continuous light, black standard option

6-sunlight behind glass

Colorimetric analysis

The N1R and SW1R analyses were performed using any of the commercially available color spectrophotometric instruments, such as the UltraScan Pro spectrophotometer from HunterLab.

Example 1：

Various fibers of the present invention were tested as described herein. The results are shown in table 1 below.

TABLE 1

Claims

1. A method for producing high strength or load bearing nylon staple fibers with additives, the method comprising:

a) Melt spinning a nylon polymer and an additive into filaments;

b) Uniformly quenching the filaments;

c) Forming a tow from a plurality of the quenched filaments;

d) Passing the tow from a series of feed rolls to a series of draw rolls while introducing steam to the tow;

e) Subjecting the steam-treated tow to drawing;

f) Annealing the drawn tow; and

g) Converting the resulting drawn and annealed tow into staple fibers;

h) Wherein the nylon staple fibers have a tenacity at break of greater than 6.5g/den and a tenacity at 10% elongation of greater than 3.0g/den, and

i) Wherein the additive is selected from pigments, additives for uv protection or additives for flame or fire retardation.

2. The method of claim 1, wherein annealing is performed under tension.

3. A high strength or load-bearing nylon staple fiber made by the process of claim 1 or 2.

4. The nylon staple fiber of claim 3 wherein the additive is a pigment present in an amount of 10 to 50,000 parts per million.

5. The nylon staple fiber of claim 3 wherein the nylon polymer is selected from the group consisting of: nylon 6,6, nylon 6, and combinations thereof.

6. The nylon staple fiber of claim 3 wherein the nylon polymer further comprises a monomeric salt of sulfonated isophthalate in an amount of 0.04 to 4 wt.% of the nylon polymer.

7. The nylon staple fiber of claim 3 wherein the nylon polymer further comprises monomeric methylpentamethylene diamine in an amount of from 0.04 to 4 percent by weight of the nylon polymer.

8. A yarn spun from the nylon staple fiber of any one of claims 3-7.

9. The yarn of claim 8 further comprising at least one companion staple fiber.

10. The yarn of claim 9, wherein the companion staple fiber is selected from the group consisting of: cellulose, modified cellulose, animal fiber, flame retardant polyester, flame retardant nylon, flame retardant rayon, flame retardant treated cellulose, meta-aramid, para-aramid, modacrylic, phenolic resin, melamine, polyvinyl chloride, antistatic fiber, polymers of 1, 4-phthalic acid and 4, 6-diamino-1, 3-benzenediol dihydrochloride, and polybenzimidazole, and combinations thereof.

11. The yarn of any one of claims 8 to 10, wherein the nylon content is 5% or greater.

12. An article, at least a portion of which comprises the nylon staple fiber of any one of claims 3-7 or the yarn of any one of claims 8-11.

13. The article of claim 12, which is a fabric.

14. The article of claim 12, which is a denim fabric.

15. The article of claim 14, wherein the denim fabric is overprinted in a color similar to the pigment contained in the nylon staple fibers.

16. The article of claim 12, which is a nonwoven fabric composite.

17. The article of claim 16, wherein the nonwoven fabric composite further comprises cellulosic fibers or recycled synthetic or natural fibers.

18. The article of claim 17, wherein the cellulosic fibers or recycled synthetic or natural fibers comprise recycled denim.

19. The article of claim 13, wherein the fabric is dyed a solid color and/or exhibits a uniform dark hue.

20. The article of claim 13, wherein the fabric exhibits improved ultraviolet light fastness.

21. The article of claim 13, wherein the fabric exhibits improved dye washfastness.

22. The article of claim 13, wherein the fabric is a camouflage print.

23. The article of claim 13, wherein the fabric exhibits reduced near infrared reflectance in the range of 600-900 nm.

24. The article of claim 13, wherein the fabric exhibits a lower and flattened short wave infrared reflectance in the 900-2500nm range.

25. The article of claim 13, wherein the fabric is flame retardant.

26. The article of claim 13, wherein the fabric exhibits improved arc rating.