JP2006501380A - Method for producing cellulosic fiber containing PTFE - Google Patents

Abstract

  The present invention relates to a method for producing a solution-spun fiber that has a reduced coefficient of friction and improved other properties such as abrasion resistance when compared to conventional solution-spun fibers. In the method of the present invention, polytetrafluoroethylene (PTFE) is incorporated into the fiber-forming material during the solution spinning process before passing through the spinneret. PTFE useful in the present invention includes PTFE powders that can be dispersed to low micron or submicron particle sizes and aqueous or organic dispersions of such highly dispersible PTFE powders. The present invention also relates to fabrics, knitted fabrics, and other products formed from solution spun fibers enhanced with the PTFE of the present invention.

Description

  This application claims priority from US Provisional Patent Application No. 60 / 415,005, filed Oct. 1, 2002, the disclosure of which is hereby incorporated by reference in its entirety.

  The present invention relates generally to a method of incorporating highly dispersible polytetrafluoroethylene (PTFE) powder into solution-spun synthetic fibers, the resulting fibers being compared to conventional solution-spun synthetic fibers. Improved properties generally associated with PTFE, such as, for example, low coefficient of friction, improved wear resistance, hydrophobicity, improved stain resistance, improved light stability, and UV resistance. Have. The present invention further relates to solution-spun fibers incorporating PTFE made by the methods described herein, and knitted fabrics, fabrics, and other products made from these solution-spun synthetic fibers.

  In the textile industry, garment manufacturers and fiber producers chemically and physically modify or enhance the basic composition of each common type of synthetic fiber to produce the desired fiber variations. I'm always trying to do that. Fiber variations have been pursued, so that improved fibers have a softer feel, better comfort, brighter and longer lasting shades, better warmth or coolness, better moisture transport or wicking, and other Provides better blendability when blended with fibers. For example, see “Fabric Link, Fabric University-Fabric Producers and Trademarks,” <http://www.fabriclink.com/Producers.html>. Therefore, there is always a need in the fiber production technology for new and innovative methods for improving the properties of synthetic fibers.

  Various manufacturing processes are known in the art for manufacturing synthetic fibers. Many synthetic fibers are produced by an extrusion process in which a thick, viscous liquid polymer precursor or composition is extruded through a small hole in a spinneret to produce a continuous, semisolid polymer. Filaments are formed. When the filament emerges from the spinneret hole, the liquid polymer first changes to a rubbery state and then solidifies. The process of extruding and coagulating filaments is commonly known as spinning. One common method of spinning man-made or synthetic filaments is commonly known as “solution spinning” or “wet spinning”.

  Typically, solution spinning or wet spinning processes use fiber forming materials dissolved in a solvent. The spinneret for forming the filament is immersed in a wet chemical bath, and when the filament of the fiber forming substance comes out of the spinneret, it is precipitated from the solution and solidified. Synthetic fibers commonly produced in solution spinning processes include, among others, rayon fibers, acrylic fibers, aramid fibers such as Kevlar® para-aramid fibers, modacrylic fibers, and spandex fibers. These synthetic fibers are made from fiber-forming materials, which are primarily water-soluble celluloses or water-soluble compounds of cellulose.

  Rayon, one of the most common synthetic fibers produced by solution spinning, is an artificial fiber composed of what is known as “regenerated” cellulose in which less than 15% of the hydroxyl hydrogens are replaced by substituents Is defined as See, for example, Rules And Regulations Under The Textile Fiber Products Identification Act, 16 CFR Part 303. In many rayon production processes, purified cellulose is chemically converted to a soluble compound, and when a solution of this compound passes through the spinneret, a flexible filament is formed, which is converted or converted to almost pure cellulose. “Played”. In order to reconvert soluble compounds to cellulose, rayon is commonly referred to as regenerated cellulose fibers.

  In order to improve the quality of the resulting solution-spun fibers, additives (eg, dyes and surfactants) may be added to the fiber-forming substance (such as cellulose) prior to extrusion. However, until the present invention, it has not been considered that the addition of polytetrafluoroethylene (PTFE) powder is feasible or beneficial in the production of solution spun fibers. In particular, it is feasible to add PTFE powder that can be dispersed to a low micron or submicron particle size or PTFE powder particles that have a primary particle size of low micron or submicron to the fiber forming material for solution spun fibers It was not shown to be.

  PTFE is generally known to give properties such as improved slipperiness and non-wetting to other materials when incorporated into other materials. For this purpose, PTFE in the form of a powder or in the form of a dispersion is useful. Dry PTFE powder products are known in the art and are generally commercially available. Several manufacturers in the fluoropolymer industry produce PTFE powder, some of which describe the PTFE particle size of the powder as being "submicron" or dispersible in submicron sizes. Yes.

  There are a variety of end uses for small particle size or submicron PTFE. For example, the incorporation of a small amount (eg, about 0.1-2% by weight) of powdered PTFE into various product compositions can provide favorable beneficial properties. When added to the ink, the incorporated PTFE provides excellent surface damage and rub resistance. When added to cosmetics, the incorporated PTFE gives a silky feel. When added to sunscreen, the incorporated PTFE provides enhanced shielding against UV radiation and enhanced SPF (sun protection index). When added to grease and oil, the incorporated PTFE provides excellent lubrication. When added to coatings and thermoplastics, the incorporated PTFE provides improved wear resistance, chemical resistance, weather resistance, water resistance, and film hardness.

Other more specific end uses for submicron PTFE powders and dispersions include, for example, incorporating a uniform dispersion of submicron PTFE particles into an electroless nickel coating, and the friction properties and wear of such coatings. Improving properties (see, for example, Hadley et al. Metal Finishing, 85: 51-53 (December 1987)); incorporating submicron PTFE particles into the surface finish for contact of electrical connectors (where PTFE particles provide abrasion resistance to the surface finish layer) (US Pat. No. 6,274,254 to Abys et al.); Incorporating submicron PTFE particles into the film-forming binder as a solid lubricant in the interfacial layer (here The interfacial layer forms part of the optical waveguide fiber) (US Pat. No. 5,181,268 to Chien); submicron PTFE powder (with granulated PTFE powder and TiO ₂ ) Incorporating into dry engine oil additives (wherein the incorporated PTFE enhances the slip properties of surfaces subjected to loads lubricated by the additive) (US Pat. No. 4,888,122 to McCready); and metals and Combining submicron PTFE particles with autocatalytically applied nickel / phosphorus for use in surface treatment systems for metal alloys (where PTFE is lubricated to the resulting surface, low friction, and ("Niflor Engineered Composite Coatings" Hay N., International, Ltd. (1989)). Specific examples of end use related to PTFE include the incorporation of PTFE in engine oils, the use of PTFE as a thickener in greases, and the use of PTFE as an industrial lubricating additive. Willson, Industrial Lubrication and Tribology, 44: 3-5 (March / April 1992).

  The beneficial effects imparted to applications and end-use systems by the addition or incorporation of PTFE particles stem from the advantageous chemical and physical properties of PTFE. In particular, PTFE is chemically inert, physically smooth (ie having a low coefficient of friction), and hydrophobic. In many applications and end uses that incorporate sub-micron PTFE powders and sub-micron PTFE dispersions (end uses as described above), the beneficial properties of PTFE are spread throughout the application or end use product composition. . Moreover, because submicron PTFE particles have a small particle size, the ratio of surface area to weight is significantly higher when compared to large PTFE particles. Thus, submicron PTFE particles can have a better beneficial effect on the system for the desired application than large PTFE particles of the same weight.

  Given the previous argument that there is always a desire to produce better synthetic fibers with improved properties in the textile industry, considering the benefits of incorporating PTFE in various applications, synthetics in fiber manufacturing technology It is clear that there is a general need for incorporating PTFE into the fiber. Obtaining fibers spun by solution spinning, for example with improved properties associated with PTFE, is especially desirable commercially. Thus, there is a clear need for convenient and inexpensive PTFE powders that can be incorporated into fiber forming materials used in the production of solution spun fibers and can be dispersed in low micron or submicron particle sizes. Furthermore, there is a need for a method that incorporates such low or submicron PTFE particles uniformly and permanently throughout the solution spun fiber as opposed to just surface treatment or coating. Uniformity and permanence of PTFE distribution across the fiber body allows knitted fabrics, fabrics and garments made from solution spun fibers to improve PTFE-related properties over time due to surface wear and tear. Guarantee that you will never lose. The present invention addresses these and other needs.

  The present invention relates to a novel method of incorporating polytetrafluoroethylene (PTFE) into synthetic solution spun fibers, and the resulting fibers have many improved properties compared to conventional solution spun fibers. It has characteristics and properties.

  In this method, PTFE powder that can be dispersed to a low micron or submicron particle size is first added to the raw material of the fiber-forming substance (such as cellulose). This fiber forming material is suitable for solution spinning of fibers. Thereafter, the fiber-forming substance or raw material containing PTFE is solution-spun into filaments or fibers. The resulting filament or fiber contains PTFE particles dispersed therein. The PTFE particles are uniformly or homogeneously dispersed in the resulting filament or fiber body. The resulting filament or fiber has improved properties associated with PTFE. For example, solution-spun fibers obtained as a result of the method of the present invention exhibit a significantly reduced coefficient of friction compared to conventional solution-spun fibers.

  Using low micron or submicron particle size PTFE powder as an additive to the fiber forming materials used in the manufacture of certain synthetic fibers makes the added PTFE produced from the fibers and such fibers It is important in terms of improving the non-wetting properties of the textile product. Accordingly, fibers incorporating PTFE (“PTFE-enhanced fibers”) are useful as industrial fiber products used in articles or products used in filtration and dewatering processes. Such PTFE-reinforced fibers are advantageously used to produce carpets, sportswear and outdoor wear fabrics, hot air balloons, car and airplane seats, umbrellas and the like. Furthermore, the fibers of the present invention are advantageously used to produce tightly woven fabrics for parachutes, boat sails, and similar applications. The combination of tight weave and PTFE-enhanced fiber hydrophobicity provides knitted and woven fabrics for clothes that are both water repellent and breathable. Inclusion of PTFE-enhanced fibers in such a textile product has other beneficial advantages such as the textile product being easy to clean.

  The method of the present invention is useful in that the resulting PTFE-enhanced solution spun fiber has many improved properties compared to conventional synthetic solution spun fibers. Some of these improved properties include, but are not limited to: reduced coefficient of friction; reduced wettability; improved stain resistance; improved detergency; Improved resistance; increased protection from ultraviolet light (UV), thereby increasing light resistance and fiber and fabric life; increased color resistance; reduced gas permeability; better wear resistance; Improved weaving index; increased fiber flexibility; reduced creaking (squeaking generally refers to the rubbing sound produced by a particular fabric); Reduction in the amount of wrinkles when incorporated into textiles and clothing products.

  Furthermore, the method of the present invention not only results in improved solution spun fibers, but the method also serves to significantly improve the overall process of producing synthetic fibers typically. For example, the increased lubricity and slipperiness of the fiber-forming material resulting from the addition of PTFE results in a reduction in production time for fiber production, a significant increase in processing speed, an increase in throughput and overall production. This leads to an increase in speed. Further, the increase in the lubricity of the fiber forming material due to the addition of PTFE increases the life of the fiber manufacturing apparatus, and overall reduces the energy consumed when the fiber manufacturing apparatus is moved.

  The present invention relates to an improved method for producing solution-spun fibers, wherein the fibers have better wear resistance and coefficient of friction than conventional solution-spun fibers known in the art. small. The method of the present invention improves fiber quality by introducing PTFE, which can be dispersed to a low micron or submicron particle size, into a fiber forming material from which the fiber is produced by a solution spinning process. To do. PTFE-enhanced solution-spun fibers made by this method have, among other properties, abrasion resistance, stain resistance, when compared to conventional solution-spun fibers known in the art. The water resistance is increasing and the coefficient of friction is significantly reduced.

  An important object of the present invention is to incorporate PTFE throughout the solution spun fiber so that the fiber contains PTFE uniformly distributed throughout its material body. Thus, every subsection or portion of the fiber has enhanced properties imparted to the fiber by PTFE. This is known in the art where PTFE is incorporated only in the surface layer of the fiber, or PTFE is applied as a surface coating to solution-spun fibers (or fabrics made from such fibers). Compared to or contrasted with other processes and fibers.

  In a preferred embodiment of the method of the present invention, the following types of PTFE are useful: PTFE powder that can be dispersed to submicron particle size; PTFE powder that can be dispersed to low micron particle size; aqueous or organic dispersion of PTFE powder that can be dispersed to submicron particle size; low micron An aqueous or organic dispersion of PTFE powder that can be dispersed to a particle size of One specific type of PTFE used in the method of the present invention is described in co-assigned international patent application PCT / US03 / 07978 filed on March 14, 2003, where: The literature is incorporated in its entirety by reference.

  As used herein, the designation “submicron particle size” means that a given amount of PTFE powder is dispersed in isopropyl alcohol (IPA) and is about 90% or more, preferably about 95% or more, more preferably Indicates that about 99% or more of PTFE particles have a particle size of about 1.00 μm or less. Furthermore, the designation “low micron particle size” means that a given amount of PTFE powder is dispersed in isopropyl alcohol (IPA), and about 95% or more of the PTFE particles have a particle size of about 10.00 μm or less. Show.

  The dispersibility of the PTFE powder down to the low micron or submicron particle size is important for performing the solution spinning process unimpeded. Unlike large sized PTFE particles that clog the spinneret and make it difficult to form the fibers, small sized PTFE particles easily pass through the spinneret holes. The method of the present invention allows PTFE that can be dispersed to low micron particle size to be used for high denier fibers, while PTFE that can be dispersed to submicron particle size is It is foreseen to be useful for molding both low and high denier fibers. The PTFE particles are uniformly or homogeneously distributed over any denier size fiber body.

  The dispersibility of the powdered PTFE particles is determined by dispersing an amount of PTFE powder in isopropyl alcohol (IPA). Then, conventional particle size analysis (for example, light scattering analysis) provides an indication of the average particle size and particle size distribution of the PTFE powder. Thus, the user may verify or confirm, for example, whether a sample of PTFE powder is fully dispersible to a (100%) submicron size or is otherwise suitable for use in a solution spinning process. it can.

  As mentioned earlier, aqueous or organic dispersions of PTFE that can be dispersed to sub-micron or low-micron particle sizes are used in solution spinning processes. The most useful PTFE dispersion in the present method comprises about 5% to about 60% by weight PTFE. A pelletized masterbatch with an appropriate concentration of PTFE (eg 5% -60%) may optionally be used for this purpose. Alternatively, dry PTFE powder that can be dispersed to sub-micron or low micron particle sizes may be directly dispersed in a fiber-forming material (such as cellulose). In certain preferred embodiments of the method of the present invention, an aqueous or organic dispersion of PTFE that can be dispersed to submicron or low micron particle sizes is first provided. Then, the process steps of the present invention for producing solution spun fibers enhanced with PTFE are used.

  Conventional solution spinning processes for producing rayon fibers involve several steps in processing or preparing the fiber forming material as a raw material for solution spinning through a spinneret. These steps are generally described in the literature as steps of dipping, pressing, crushing, aging, xanatahation, dissolution, aging, filtration, degassing, and wet bath spinning. See for example. The process for producing PTFE-enhanced solution spun fibers is advantageously based on a conventional solution spinning process that is suitably modified. Typical process steps for PTFE-enhanced solution spun fibers are described below, but are conveniently used to describe conventional solution spin process steps for rayon for convenience. The same terminology is used.

  In the production method of rayon, cellulose is typically used as a raw material. Specifically, purified cellulose is used as a fiber forming material in the production of rayon. Purified cellulose is prepared from specially processed wood pulp, often referred to as “dissolved cellulose” or “dissolved pulp” and is distinguished from lower grade pulp used for paper manufacturing and other purposes. The Dissolved cellulose is characterized by a high amount of α-cellulose, which means that cellulose consists mainly of long chain molecules and is relatively free of lignin, hemicellulose, or other short chain carbohydrates. means. Purified cellulose is often obtained in the form of cellulose sheets.

  In preparation for feeding raw materials for solution spinning of rayon fibers, the cellulose sheet is first wetted with a wetting agent. This wetting process provides one way of incorporating PTFE according to the present invention. In conventional spinning processes, the wetting agent is usually water. However, in certain embodiments of the invention, the cellulose sheet may be wetted with an aqueous dispersion of PTFE that can be dispersed to sub-micron or low-micron particle sizes. For example, PTFE is mechanically incorporated into the cellulose sheet by mixing, stirring, or blending. As shown below, in an alternative embodiment, PTFE is incorporated into the cellulose at any processing step or time prior to spinning the rayon filament.

  In the next treatment step, “dipping”, a wet cellulose sheet (wet with an aqueous dispersion of highly dispersible PTFE) is saturated with an aqueous solution of caustic soda (or sodium hydroxide). The wet cellulose sheet is soaked for a time sufficient to convert some cellulose to “soda cellulose” (or sodium salt of cellulose). During the next processing step, called “squeezing”, soda cellulose is mechanically squeezed to remove excess caustic soda solution.

  The soda cellulose is then mechanically crushed into smaller sized pieces, increasing its active surface area, thereby making the soda cellulose easier to process. The cellulose thus crushed is typically referred to as “white crumb”. In the next step, “aging”, this white crumb is left in contact with oxygen in the room air. The white crumb is partially oxidized by contact with oxygen (due to the high alkalinity of white crumb), and the cellulose in the white crumb is decomposed to a low molecular weight (that is, a short chain molecule). The aging time and degradation conditions are short enough to obtain a manageable viscosity in solution spinning, but carefully so as to create a long enough chain length to impart good physical properties to the solution-spun fiber product. Be controlled.

After the above “aging” step, white crumb is placed in a stirrer or other mixing vessel and treated with gaseous carbon disulfide (CS ₂ ) in the “xanthogen oxidation” step. In certain embodiments of the present invention, the incorporation of an aqueous dispersion of PTFE is advantageous when the white crumb is placed in a stirrer and / or treated with CS ₂ in the stirrer immediately after the aging process. Done. Soda cellulose reacts with CS ₂ to form xanthate groups. CS ₂ also reacts with an alkaline medium to form inorganic impurities, which makes the cellulose mixture a characteristic yellow color. Such materials resulting from the xanthogen oxidation process are typically referred to as “yellow crumb”.

  Thereafter, in the “dissolution” step, yellow crumb is dissolved in an aqueous caustic solution. In some embodiments of the invention, an aqueous dispersion of highly dispersible PTFE is advantageously added to the yellow crumb at this stage. Yellow crumb cannot be completely or fully dissolved at this stage. Specifically, because the cellulose xanthate solution or suspension has a high viscosity, it is typically referred to as “viscose”. Viscose is left for a period of time to “ripen”. During aging, two important chemical processes occur. It is redistribution and loss of xanthate groups.

  The viscose is then filtered to remove undissolved or undispersed material that may disrupt the spinning process and cause defects in the rayon filament. In embodiments of the invention where highly dispersible PTFE is already incorporated into the viscose at this stage, this “filtration” process is properly controlled, for example by using an appropriate filter size, As a result, the added PTFE particles are not filtered out of the viscose. Further, in order to avoid bubbles or weak points in the fine rayon filament, the viscose is degassed prior to extrusion, that is, air bubbles entrained in the viscose are removed.

Aged and degassed viscose can be used as a feedstock to the spinneret for solution spinning of PTFE-enhanced rayon fine filaments. Specifically, viscose is extruded through a spinneret—an instrument resembling a shower head having a plurality of small diameter channels or holes—but into a wet chemical bath. In some embodiments of the present invention, an aqueous dispersion of highly dispersible PTFE may be added to the viscose when it is about to be put into the spinneret. Each hole in the spinneret produces a fine filament of viscose. As the viscose exits the spinneret as a filament, it comes into contact with the chemicals in the wet chemical bath. These chemicals can be solutions containing sulfuric acid, sodium sulfate, and usually Zn ²⁺ ions. At this point, several processes take place, whereby the cellulose in the filaments is regenerated and precipitates out of solution. For example, water emanates from the extruded viscose, increasing the concentration in the filament beyond the solubility limit. The xanthate group in the filament forms a complex with the Zn ²⁺ ion, which causes the cellulose chains to be stretched together. The acidic spinning bath converts the xanthate functional group into an unstable xanthate group, thereby spontaneously losing CS _{2 and} regenerating the free hydroxyl group of cellulose. As a result, fine filaments of PTFE-enhanced cellulose or rayon are formed.

  After the PTFE-enhanced rayon filaments are formed, the filaments can be stretched with relatively little movement of the inner cellulose molecule chains. This allows the molecular chains to be stretched and oriented along the filament axis to provide the properties necessary for use as a fiber product fiber. The PTFE-enhanced rayon fiber is then washed to remove salts and other water soluble impurities present in the freshly regenerated rayon. The PTFE-enhanced rayon filament can then be cut to the appropriate length required for the intended use. For example, if you are going to use PTFE-enhanced rayon as staples (ie discontinuous length fibers), pass a bundle of filaments-often called "tow"-through a rotating cutter to obtain the fibers However, it can be processed in much the same way as cotton fibers.

  PTFE-enhanced solution spun fibers produced by such methods are then produced into woven and knitted fabrics. Such fabrics or knitted fabrics have enhanced properties typically associated with the addition of PTFE to the product. For example, woven fabrics and knitted fabrics exhibit a significantly reduced coefficient of friction, which can be an advantageous property of woven fabrics and knitted fabrics intended for apparel used in sports and recreational activities. Other advantageous properties of the solution-spun fibers of the present invention include the exceptional wear resistance exhibited by PTFE-reinforced fibers.

  Specifically, the abrasion resistance of a fiber can be determined by performing an abrasion test on solution-spun fibers and / or fabrics made from the fibers of the present invention. The abrasion test includes a Taber test, a Mace test, and a Pilling test. Similarly, tests can be performed to determine fabric tenacity, fabric elongation, and draw. A full range of tests similar to those commonly used in the industry to analyze the properties of solution spun fibers are used to test the fibers of the present invention. Tests used in other industries and other scientific test methods can also be used to characterize the fibers and fabrics of the present invention.

  The method and configuration of the present invention will be better understood through the examples detailed below. These examples are intended to illustrate the invention and should not be construed as limiting the invention in any way.

Example 1: Production of PTFE-reinforced rayon fibers In this example, PTFE-reinforced rayon fibers were produced according to the method of the present invention for comparison with conventional rayon fibers. Specifically, in this example, three types of cellulose were first tested to determine their suitability for rayon production. It is a cosmetic cotton ball available at pharmacies and two types of wood cellulose products. All three cellulose mold samples were immersed. After soaking both samples of wood cellulose pulp, an undesirable brown material was produced, which may be due to the presence of lignin, hemicellulose, and short chain carbohydrates. Conversely, the first test of cosmetic cotton balls yielded a clear orange cellulose xanthate solution with an essential high viscosity. Based on the results of these tests, only cosmetic cotton balls were selected as raw materials for use in further experiments.

  In further experiments, a cosmetic cotton ball cellulose material was mechanically crushed to increase the surface area, thereby facilitating processing of the cellulose. Then, the cellulose was immersed. Specifically, 1 gram of crushed cellulose (“Sample 1”) was wetted with 5 mL of water in a beaker. Next, 50 mL of 15% sodium hydroxide solution was added to the beaker with continuous stirring, producing sodacellulose. The mixture was left or soaked for about 1 hour. Visual observation of the mixture revealed that the soaked mixture had a “white crumb” appearance in a clear liquid.

  Separately, 1 gram of crushed cellulose (“Sample 2”) was wetted with a 5 mL aqueous dispersion of submicron PTFE in a beaker. The specific PTFE used in this example was a PTFE product commercially available from Shamrock Technologies, Inc., the assignee under the trade name “NanoFLON W50C”. In a further process similar to that of Sample 1 above, 50 mL of 15% sodium hydroxide solution was added to Sample 2 with continuous stirring. The sample 2 mixture was soaked for 1 hour. Visual observation of the mixture of Sample 2 reveals that the soaked mixture has a “white crumb” appearance in a turbid liquid, which indicates that a soda cellulose / PTFE mixture is formed. Was consistent with that.

  Next, the soda cellulose of sample 1 and the soda cellulose / PTFE of sample 2 were each placed on a separating mesh filter and mechanically squeezed to remove excess caustic soda solution, thereby producing “white crumb”. For sample 1, the removed solution was slightly yellow and turbid, while for sample 2, the removed soda solution looked like a suspension of PTFE.

Next, in the “xanthogen oxidation” step, 25 mL of CS ₂ was added to each “white crumb” mixture in a beaker with continuous stirring. Samples 1 and 2 were both stirred for 3 hours. After 3 hours, the white crumb of Sample 1 turned orange-yellow and had a very swollen appearance in a clear medium. The white crumb of Sample 2 turned whitish yellow and was not transparent. The excess liquid was then carefully removed from each sample, leaving what was typically called “yellow crumb” for each of the two samples.

  The yellow crumbs of Sample 1 and Sample 2 were gradually dissolved in 15 ml of 15% NaOH solution with stirring. After dissolution, Sample 1 became a bright orange viscose solution. In contrast, Sample 2 became a pale orange solution. The two viscoses generated from samples 1 and 2 were left to “age” for 1 hour and freed bubbles (introduced into each viscose by stirring) were removed by degassing.

Samples 1 and 2 of viscose were then subjected to a solution spinning laboratory simulation. Specifically, a disposable syringe with a 1 mm diameter needle hole was used to simulate the function of a spinneret used in commercial equipment for spinning rayon filaments. When the viscose of Sample 1 was extruded through an injector into an acidic wet bath, rayon filaments were regenerated or produced. Specifically, the solution in this acidic bath contained 20% H ₂ SO ₄ (sulfuric acid), 10% Na ₂ SO ₄ (sodium sulfate), and 10% ZnCl ₂ (zinc chloride). Sample 2 viscose was also extruded through a syringe into a similar acidic bath, producing PTFE-enhanced rayon filaments.

  After forming these rayon filaments, they were each subjected to a “stretching” procedure. Specifically, each freshly regenerated rayon filament was stretched by pinching with a pair of tweezers (although the cellulose chains were still relatively mobile). Visual observation showed that the PTFE-enhanced rayon filament (Sample 2) was stretched over the Rayon filament of Sample 1 that did not contain PTFE. After this stretching or stretching test, the freshly regenerated rayon filaments were washed together with water several times and dried.

  Both rayon filaments were then analyzed using multiple laboratory analysis techniques. In one analysis, filaments were analyzed using Fourier Transform Infrared Spectroscopy (FTIR). The FTIR spectrum confirmed that the two filaments produced in the laboratory were genuine rayon. The FTIR spectrum of the PTFE-enhanced rayon filament (Sample 2) did not show any PTFE-specific peaks.

  In another analysis, rayon filaments were analyzed using differential scanning calorimetry (DSC). The DSC curve of PTFE-enhanced rayon filament (Sample 2) showed a small peak corresponding to the presence of PTFE. A small peak was observed at 328.6 ° C. for the first heating and 329.7 ° C. for the second heating. From these peaks, ΔH (enthalpy) values were calculated to be 4.1 and 3.9 J / g, respectively. From these values, the amount of PTFE in the PTFE-enhanced rayon filament (Sample 2) was estimated to be about 5% by weight.

  In yet another analysis, both samples of rayon filaments were subjected to thermogravimetric (TGA) analysis. The TGA curve for PTFE-enhanced rayon filament (Sample 2) showed that PTFE was present at a concentration of about 5.3%.

Claims (18)

Prepare viscose of soluble fiber forming material,
During the preparation of viscose, polytetrafluoroethylene (PTFE) material is added to the soluble fiber forming material,
Extruding viscose with added PTFE material through a spinneret into a wet bath to form fibers;
The manufacturing method of the fiber containing this.   The method of claim 1, wherein the addition of PTFE material to the fiber forming material comprises dispersing PTFE particles having a size of about 1 micron or less in the viscose.   The method of claim 1, wherein the addition of the PTFE material to the fiber forming material comprises the addition of PTFE powder that can be dispersed to a submicron particle size.   The method of claim 1, wherein the addition of PTFE material to the fiber forming material comprises the addition of an aqueous dispersion of PTFE powder that can be dispersed to a low micron particle size.   5. The method of claim 4, wherein the aqueous solvent dispersion of PTFE powder comprises about 20% to about 60% by weight PTFE.   The method of claim 1, wherein the addition of the PTFE material to the fiber forming material comprises the addition of an organic solvent dispersion of PTFE powder that can be dispersed to a low micron particle size.   The method of claim 1, wherein the addition of PTFE material to the fiber forming material comprises dispersing PTFE particles having a size smaller than the spinneret channel.   The method of claim 1 wherein the addition of PTFE material to the fiber forming material comprises introducing dispersible PTFE powder in the form of a pelletized masterbatch.   The method of claim 8, wherein the masterbatch comprises about 5% PTFE to about 60% PTFE.   The method of claim 1, wherein the fiber-forming material comprises a material selected from the group consisting of cellulose, cellulose compounds, and any combination thereof.   The preparation of the fiber forming material viscose includes a dipping process, a pressing process, a crushing process, an aging process, a xanthogen oxidation process, a dissolution process, an aging process, a filtration process, and a degassing process. The method according to claim 1, wherein the addition of the polytetrafluoroethylene (PTFE) material to the fiber forming material comprises the addition of PTFE during at least one step during the preparation of the viscose.   Extruding viscose with added PTFE material through the spinneret into the solution to form fibers solidifies the extruded viscose so that the PTFE particles are dispersed substantially throughout the fiber body. The method of claim 1 further comprising:   A woven fabric comprising fibers produced by the method of claim 1.   A synthetic fiber comprising a wet-spun extrudate of cellulosic material; and a dispersion of PTFE particles in the wet-spun extrudate.   The synthetic fiber of claim 14, wherein the PTFE particles are substantially uniformly distributed throughout the wet spin extrudate.   The synthetic fiber of claim 14, wherein the dispersion of PTFE particles comprises PTFE particles having a size of about 1 micron or less.   A woven fabric comprising the synthetic fiber according to claim 14.   A product comprising the synthetic fiber according to claim 14.