JP2006501381A - Process for producing fibers and fiber products with improved properties by incorporating polytetrafluoroethylene (PTFE) into synthetic melt-spun fibers - Google Patents

Abstract

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

Description

  This application claims priority from US Provisional Patent Application No. 60 / 415,039, filed Oct. 1, 2002, the disclosure of which is incorporated herein by reference in its entirety.

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

  In the textile industry, garment manufacturers and fiber producers have a softer feel, better comfort, brighter and longer lasting shades, better warmth or coolness, better moisture transport or wicking, and other In order to create fiber variations that give better blendability when blended with fibers, there is always an attempt to chemically and physically modify the basic composition of each general type of synthetic fiber. 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 extrusion, in which a thick viscous liquid polymer precursor or composition is extruded through small holes in a spinneret to produce a continuous, semi-solid polymer. A filament is 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. A common method of spinning filaments of melt spun synthetic fibers is commonly known as “melt spinning”.

  Typically, in the melt spinning process, the fiber forming material is melted into a viscose liquid state for extrusion through a spinneret. After extrusion from the spinneret, the fiber material or filament is solidified by air cooling. Typical fibers formed by melt spinning include polyester, nylon, and polypropylene, among others.

  Polyester fibers, one of the more common melt-spun fibers, are any long chain synthetic polymer whose fiber-forming material is composed of at least 85% by weight of a substituted aromatic carboxylic ester by the Federal Trade Commission. Is defined as an artificial fiber. Polyester fibers are generally produced by extruding (or spinning) a polyester melt through a spinneret having a plurality of holes at high pressure (eg, 3,000 psig) and high temperature (eg, 500 ° F.). Once extruded, the polyester fibers are drawn and woven to have the desired fiber properties. Typically, micro-pollutants are removed from the molten polyester stream or feed prior to fiber spinning in order to prevent clogging of small holes in the spinneret that are approximately 25-500 μm in diameter. In the case of low denier fibers, smaller sized contaminants and particles must be removed from the melt prior to extrusion. “Pall Corporation-Polyester Fiber Production,” <http://domino.pall.com/www/weblib.nsf/pub/354559E3AFA95F9885256863004BF4C4?opendocument.>.

  In order to improve the quality or properties of the resulting melt spun fibers, additives (eg, dyes and surfactants) may be added to the polymer or fiber forming material (such as a polyester melt) prior to extrusion. However, polytetrafluoroethylene (PTFE) powder (where the powder can be dispersed to a low micron or submicron particle size, or the particles of PTFE powder have a primary particle size in the low micron or submicron range. It has not been shown prior to the present invention that adding to the fiber-forming material has any advantage in the production of improved melt spun fibers.

  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 that is in the form of a powder or in the form of an aqueous or organic 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, incorporation of a small amount (eg, about 0.1-2% by weight) of powdered PTFE into various product compositions can provide the following beneficial beneficial properties: (i) When added to the ink, PTFE Gives excellent surface damage resistance and abrasion resistance; (ii) When added to cosmetics, PTFE gives a silky feel; (iii) When added to sunscreen, PTFE provides UV shielding (Iv) When added to greases and oils, PTFE gives excellent lubrication; (v) When added to coatings and thermoplastics, PTFE Provides improved wear, chemical resistance, weather resistance, water resistance, and film hardness.

Other more specific end uses for submicron PTFE powders and dispersions include: (i) incorporating a uniform dispersion of submicron PTFE particles into an electroless nickel coating, and the friction properties of such coatings and Improve wear characteristics (see, for example, Hadley et al. Metal Finishing, 85: 51-53 (December 1987)); (ii) incorporate submicron PTFE particles in 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.); (Iii) film with submicron PTFE particles as a solid lubricant in the interfacial layer To be used in the forming binder (where the interfacial layer forms part of the optical waveguide fiber) (US Pat. No. 5,181,268 to Chien); (iv) submicron PTFE powder (granulated PTFE powder and TiO _{(With 2} ) for use in dry engine oil additives, where the additive enhances the sliding properties of the loaded surface (US Pat. No. 4,888,122 to McCready); and (v) for metals and metal alloys Combining submicron PTFE particles with autocatalytically applied nickel / phosphorus for use in surface treatment systems (where PTFE is lubricated, low friction and wear resistant on the resulting surface) ("Niflor Engineered Composite Coatings" Hay N., International, Ltd. (1989)). Specific examples of added end uses for PTFE include the incorporation of PTFE into 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).

  For many applications or end uses that incorporate submicron PTFE powders and submicron PTFE dispersions (end uses as described above), the beneficial effect imparted to the application or end use system is the chemical nature of the PTFE particles. Derived from inertness and / or small coefficient of friction of PTFE particles. Moreover, submicron PTFE particles having a small particle size have a significantly higher ratio of active surface area to weight when compared to larger PTFE particles. Thus, submicron PTFE particles can better spread the beneficial effects to the desired application system than larger sized PTFE particles of the same weight.

  Taking into account the previous discussion that there is always a need to produce synthetic fibers with improved properties in the textile industry and the usefulness of PTFE in various applications, PTFE, especially low micron or submicron A need for a convenient and inexpensive method that incorporates PTFE powder that can be dispersed in particle size into the fiber-forming material, so that the fibers spun by the melt spinning process have improved properties associated with PTFE. Is clearly present in the art. In addition, knitted fabrics, fabrics, and garments made from such fibers by uniformly and permanently incorporating low micron or submicron PTFE particles (as opposed to just a surface coating) throughout the melt spun fiber, There is a need for a method that ensures that the beneficial properties associated with PTFE are not lost over time due to surface wear and tear. The present invention addresses these and other needs.

  The present invention relates to a novel method of incorporating polytetrafluoroethylene (PTFE) into synthetic melt spun fibers, and the resulting fibers have many improved properties compared to conventional melt spun fibers. have. In this method, PTFE powder, which can be dispersed to a low micron or submicron particle size, is incorporated into a desired fiber forming material (such as a polyester melt), from which filaments or fibers are produced by a melt spinning process. The resulting “PTFE-enhanced” melt spun fiber has PTFE particles dispersed throughout the filament body. These PTFE-enhanced meltspun fibers in which PTFE is incorporated directly into the body of the filament have improved properties associated with PTFE. For example, melt spun fibers obtained as a result of the method of the present invention exhibit a significantly reduced coefficient of friction when compared to conventional melt spun fibers.

  Using PTFE powder with a low or submicron particle size as an additive to polymers or fiber forming materials used to make certain synthetic fibers means that PTFE is made from fibers and such fibers. This is important in terms of improving the non-wetting property of the textile product. Therefore, fibers containing PTFE are useful for producing textiles that are used to produce industrial filtration and dewatering equipment. Such fibers, including PTFE, are also advantageously used to produce carpets, fabrics for sports and outdoor wear, hot air balloons, car and airplane seats, umbrellas and the like. Furthermore, the fibers of the present invention are also advantageously used to produce tightly woven fabrics used for parachutes, boat sails, and similar applications. The combination of tight weave and water repellency provides a knitted or garment fabric that is water repellent and breathable. Incorporating PTFE into such textiles results in other advantages such as making the textiles easier to clean.

  The method of the present invention is useful in that the resulting PTFE-enhanced solvent spun fibers have several improved properties compared to conventional synthetic melt spun fibers. These improved properties include, but are not limited to: reduced friction coefficient; reduced wettability; improved stain resistance; improved washability; improved opacity; (UV) increased protection, thereby increasing light resistance and fiber and fabric life; increased color resistance; reduced gas permeability; better wear resistance; denser weave; Improved index; increased fiber flexibility; reduced squeakage (a squeak generally refers to the sound of rubbing created by a particular fabric); PTFE-reinforced fibers in fabrics and clothing products Decrease in wrinkle amount when incorporated.

  Furthermore, the method of the present invention not only results in improved melt spun fibers, but the method also serves to significantly improve the overall process of typically producing synthetic fibers. 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 process for producing melt spun fibers, where the fibers have better wear resistance and a lower coefficient of friction than melt spun fibers known in the art. The method of the present invention involves the introduction of PTFE into a polymer or fiber forming material that can be dispersed to a low or submicron particle size when the fiber is formed by a melt spinning process. It improves quality. The PTFE-enhanced melt-spun fibers produced by the method of the present invention are wear and stain resistant, among other properties, compared to conventional melt-spun fibers known in the art. , The water resistance is increased, and the coefficient of friction is significantly reduced.

  As a result of the present invention, PTFE is incorporated throughout the melt spun fiber so that the fiber material contains uniformly distributed PTFE particles. This is in contrast to processes and fibers in the art where PTFE is applied only to the surface of the melt-spun fiber or only to the surface of the fabric made from the melt-spun fiber and thus will not wear out. is there.

  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; and low An aqueous or organic dispersion of PTFE powder that can be dispersed to a micron particle size. One specific type of PTFE that is useful in the method of the present invention is PTFE as described in international patent application PCT / US03 / 07978, filed on March 14, 2003 and assigned simultaneously. The literature is hereby incorporated in its entirety herein 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. Indicates.

  The dispersibility of the PTFE powder down to a low micron or submicron particle size is important for performing the melt spinning process unimpeded. Unlike large sized PTFE particles that clog the spinneret and make it difficult to form the fiber, small sized PTFE particles pass easily through the spinneret. 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 low. It is foreseen to be useful for molding both denier and high denier fibers. The PTFE particles are uniformly or uniformly distributed throughout the body of any denier size fiber.

  The dispersibility of the powdered PTFE particles is determined by dispersing an amount of PTFE powder in isopropyl alcohol (IPA). Then, the average particle size and the index of the particle size distribution of the PTFE powder are obtained by conventional particle size analysis (for example, light scattering analysis). Thus, the user can verify, for example, whether a sample of PTFE powder can be completely dispersed to a (100%) submicron size, or otherwise suitable for use in a melt spinning process or Can be confirmed.

  As noted above, aqueous or organic dispersions of PTFE powder that can be dispersed in either submicron or low micron particle sizes can be used in the methods of the present invention. The most useful dispersions of PTFE in the present method typically contain from about 20% to about 60% by weight PTFE. Alternatively, dry PTFE powder that can be dispersed in either sub-micron or low micron particle size may be dispersed directly in the fiber-forming material.

  The fiber-forming polymeric substances that are considered for use in the present invention include, but are not limited to, polyester, nylon, and polypropylene, among other fiber-forming thermoplastic resins.

  In certain preferred embodiments, a PTFE powder that can be dispersed to either a low micron or submicron particle size is first provided. Thereafter, PTFE is incorporated into the fiber-forming polymer used in the manufacture of melt spun fibers. In an exemplary embodiment, poly (ethylene) terephthalate (PET) can be used as the fiber-forming polymer.

  Submicron or low micron dispersible PTFE powders are incorporated into fiber-forming polymers (such as PET) by three basic methods: 1) Powders obtained by drying dispersible PTFE powders into fiber-forming polymers 2) introducing the dispersible PTFE powder into the fiber-forming polymer in the form of an aqueous or organic dispersion; or 3) introducing the dispersible PTFE powder into the fiber-forming polymer. It is introduced in the form of a pelletized masterbatch. In essence, the highly dispersible PTFE described herein can be introduced at any stage of the fiber spinning melt spinning process as long as the fiber-forming polymer has not passed through the spinneret.

  With regard to the third method of incorporating PTFE described above, a master batch of pigment and flame retardant is formed, and a PTFE pelletized master batch is formed in the same manner as that incorporated into melt-spun fibers, and the fiber molding height is increased. Incorporate into the molecule. In some embodiments, the introduction of highly dispersible PTFE in the form of a pelletized masterbatch is preferred. The PTFE masterbatch in the fiber-forming polymer useful in the present invention typically comprises about 5% to about 60% PTFE, especially about 40% to about 45% PTFE.

  This introduction of highly dispersible PTFE powder into the fiber-forming polymer results in improved flow characteristics during extrusion, improved production speed, and significant production time due to the lubricity imparted throughout the fiber-forming process. A reduction is brought about.

  In some embodiments, melt spun fibers made in accordance with the present invention are fine fibers of about 10 denier or less. However, thick and coarse melt-spun fibers incorporating PTFE can also be produced.

  PTFE-enhanced melt spun fibers produced by the method of the present invention are incorporated into fabrics and knitted fabrics, whereby the fabrics and knitted fabrics are augmented typically associated with the addition of PTFE to products and compositions. It has the characteristics. For example, fabrics and knitted fabrics made with the fibers of the present invention can exhibit a significantly reduced coefficient of friction. Woven fabrics and knitted fabrics having such properties are useful for producing clothing intended to be worn in sports and recreational activities. Other desirable properties of the melt-spun fibers enhanced with the PTFE of the present invention include, for example, the exceptional wear and stain resistance exhibited by the fibers, the light and UV resistance of the fibers, the color of the fibers Resistance, and resistance to fiber degradation.

  Specifically, the abrasion resistance of a fiber can be determined by performing an abrasion test on a PTFE-enhanced fiber and / or a fabric made from the PTFE-enhanced fiber 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. Determine tensile strength, fabric elongation, and stretch. In general, a full range of tests similar to those commonly used in the industry to analyze the properties of melt spun fibers can be 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.

  In an embodiment of the present invention, it is desirable to form a composite fiber using this method of incorporating PTFE into a fiber-forming polymer resin during the spinning of a synthetic composite fiber. Composite fibers are generally described as fibers that contain two polymers with different chemical and / or physical properties, are extruded from the same spinneret, and contain both polymers in the same filament. Is done. Typically, the advantages afforded by bicomponent fibers include the thermal bonding of two polymers, the self-bulking of the fibers, the ability to produce fibers with unique cross-sections, and special advantages at low cost. The advantage of the polymer or additive is obtained.

  The most commonly commercially available composite fibers have one of the following configurations. It is a sheath / core; side-by-side; or an eccentric sheath / core. However, any composite fiber configuration would benefit from the method of the present invention. Typical polymer combinations used in the synthetic fiber industry for the manufacture of composite fibers include fibers having a polyester core, including a copolyester sheath; fibers having a polyester core, including a polyethylene sheath; and polyethylene Examples include fibers having a sheath and a polypropylene core.

  In certain embodiments of the invention where bicomponent fibers are sought, a polymer such as poly (ethylene) terephthalate (PET) is used as the core while the sheath is incorporated according to the method of the invention. A fiber having a sheath / core configuration such as containing a polymer (such as PET) having highly dispersible PTFE particles can be produced. For example, in certain embodiments, a composite fiber is produced in which the sheath comprises about 2% to about 40% or more PTFE. Some advantages of composite fibers formed in accordance with this method include not only cost savings because PTFE is incorporated only into the fiber sheath, but the fiber core is also very strong This includes that the tensile strength is maintained.

  The method and configuration of the present invention will be better understood through the examples detailed below. Moreover, some of the improved properties of the PTFE-enhanced melt spun fibers of the present invention are discussed in more detail in the examples below. These examples are not intended to limit the disclosure of the present invention in any way, but are intended to illustrate specific embodiments and features of the methods and fibers disclosed by the present invention.

Example 1: Friction test of fabric made with melt-spun fiber enhanced with PTFE In this example, one knitted sleeve made from melt-spun fiber with PTFE incorporated into the fiber according to this method A friction test was performed to compare the properties of the other knitted sleeves made from conventional melt-spun fibers without PTFE incorporated.

  Various friction tests exist in the art to determine the wear resistance, slip properties, and overall friction behavior of melt spun fibers. During this example, a clear and very sensitive type of friction test (based on ASTM D-5181) typically used in printing inks tests the wear and friction properties of these knitted sleeves. It was decided that it would provide a direct and decisive method. This friction test method is carried out using a Sutherland Ink Rub Tester, but is modified appropriately in this example for use in fabrics made from melt spun fibers. This friction test is sensitive and is probably much more affected by trained operators than other standard friction tests typically used in the fiber or textile industry.

  Specifically, the synthetic fibers used to make the sleeves for this example are made of PET, which is typical for the production of polyester fibers, discussed in detail above. It is a polymer. For sleeve 1, after forming the polyester fiber reinforced with PTFE and making the sleeve, the particle size of low micron or submicron so that the amount of PTFE in the resulting sleeve is about 5% by weight. PTFE that can be dispersed in PET polymer resin was incorporated. The PTFE reinforced fiber denier was 240 and the denier per filament (DPF) was 7.06.

  Sleeve 1 was made by knitting polyester fibers reinforced with PTFE of the present invention using a 4-inch cylinder and 144 needles in a jersey knit process. For sleeve 2, PTFE was not incorporated into the PET polymer resin used to produce the polyester fibers that make up the sleeve. The polyester fiber used for sleeve 2 was melt-spun in the same manner as for sleeve 1. Sleeve 2 was knitted using the same jersey knit method as sleeve 1.

  A friction test was then performed on both sleeves to determine the wear resistance of each sleeve. Friction tests were performed using Sutherland Ink Rub Tester. Within the tester, each sleeve was rubbed at a "slow speed" (ie 32 cycles per minute) with a 4 pound weight.

  During the test, Standard Receptor Stock (# 5 ASTM D-1581) was first secured to a 4 pound weight. Then sleeve 1 was placed on the pad of Sutherland Ink Rub Tester. Standard Receptor Stock was placed on sleeve 1 and secured by Ink Rub Tester's weight arm. Then, the number of strokes was set to 450 and the frictional wear test was started. After the 450 strokes were completed, a 4 pound weight was removed from the fabric. The same test procedure was used for sleeve 2.

  Sleeves 1 and 2 were compared visually to determine the level of wear caused by the friction test. Specifically, each sleeve was rubbed with the Standard Receptor Stock and carefully examined by eye to determine which sleeve had the lesser number of scratches. It was determined that knitted sleeve 1 (manufactured from 5% PTFE fiber) had less scuff than sleeve 2 (manufactured from 0% PTFE fiber). These results show that the incorporation of PTFE provided the fibers with improved wear resistance.

Example 2: Friction test of fabric made with melt-spun fibers reinforced with PTFE In this example, sleeves 3 and 4 are identical to each of sleeves 1 and 2 discussed in Example 1 above. Formed by the method. Therefore, sleeve 3 was made of polyester fiber incorporating PTFE, while sleeve 4 was made of conventional polyester fiber. In this example, the friction test using Sutherland Ink Rub Tester was performed again. However, in this example, the performance of each sleeve was measured against a Black Magenta Ink reference printed film without wax.

  Sleeve 3 and Sleeve 4 were processed through the Sutherland Ink Rub Tester using the same general procedure (slow speed and weight) as described above for the Sleeve 1 and Sleeve 2 tests (Example 1). However, in this example, the reference print film was first placed on the tester pad. The test sleeves (Sleeve 3 and then Sleeve 4) were fixed to a 4 pound weight and rubbed against the reference print film for 450 strokes. After the rubbing stroke, sleeves 3 and 4 were visually inspected to assess the number of scratches on them. The reference print film was similarly examined and evaluated for damage thereto. When visually observed, it was found that sleeve 3 was less rubbed than sleeve 4. Furthermore, the sleeve 3 did not damage the printed ink film more than the sleeve 4. These results show that the sleeve 3 with PTFE-enhanced fibers has better wear resistance than the sleeve 4 with conventional melt-spun fibers that do not contain PTFE.

Example 3: Friction coefficient testing of fabrics made with melt-spun fibers enhanced with PTFE In this example, fabrics made with conventional polyester fibers and with polyester fibers incorporating PTFE according to the present invention Tests were conducted to determine and compare the dynamic coefficient of friction for the fabric. Sleeves 5 made from conventional fibers and sleeves 6 made from PTFE-reinforced fibers were tested in this example. These sleeves were manufactured or knitted in the same manner as sleeves 2 and 1 (Example 1), respectively.

The coefficient of friction test performed in this example is a sliding or tensile test, which helps to measure the coefficient of friction of each sleeve. During the test, sleeve 5 (with PTFE-free fibers) was first secured to the surface of a friction test machine (Altek Model 9505A, available from ALTEK Company (245 East Elm Street, Torrington, CT 06790 USA)). . This machine is equipped with a 2000 gram sliding weight. The sliding weight was placed on the sleeve 5 and the friction coefficient indicator of the friction test machine was engaged. The pulling speed was set to 20 inches per minute and pulling was started. COF values were obtained from the machine's coefficient of friction (COF) indicator. The test was repeated 6 times and the average COF value for sleeve 5 was obtained. A similar test procedure was used to obtain an average COF value for sleeve 6 containing fibers reinforced with PTFE. The obtained COF results are shown in Table 1 below.

  The results shown in Table 1 show that knitted sleeves made of fibers with 5% PTFE (sleeve 6) have a lower coefficient of friction than sleeves made of fiber without PTFE (sleeves 5). It shows that he was doing.

Example 4: Friction coefficient test of fabrics made with PTFE-enhanced melt spun fibers using the slip angle test In this example, sleeves 7 and 8 are sleeves as described in Example 3 above. 5 and 6 were formed in exactly the same manner. Thus, sleeve 7 was made of polyester fiber without PTFE, while sleeve 8 was made of polyester fiber reinforced with PTFE according to the present invention. The COF test procedure used in this example includes a sliding angle test to study the friction characteristics of each sleeve and determine the static friction coefficient of each sleeve. A Sliding Angle Coefficient of Friction Tester (Model # 32-35) was used for this purpose. Within the tester, three different pairs of surface materials were used. (1) Mylar film; (2) printing paper (70 # opus gloss); and (3) processed C-184 foil.

  To start the test, sleeve 7 was fixed to the weight. The mating surface material was placed in a holder in a sliding tester. Then the weighted sleeve 7 was placed neatly on the mating surface material prepared to measure its sliding angle. Lifting one end of the mating surface, the angle at which the weighted sleeve 7 begins to slide was determined. The measurement was repeated 5 times, and as a result, the average value of the slip angle with respect to the sleeve 7 could be calculated. The COF value was calculated from the average slip angle value. These measurements and COF calculations were repeated for each of three different pairs of surface materials.

The same test procedure was used for sleeve 8 (with PTFE reinforced polyester fibers according to the present invention). The results of the tests of this example are shown in Table 2 below.

  These results show that sleeve 8, which is a polyester knitted sleeve with 5% PTFE incorporated into the fiber, is small compared to sleeve 7 made from conventional polyester fiber without PTFE additives. It shows that it had a coefficient of friction.

Example 5: Measurement of increased UV protection for fabrics made with PTFE-enhanced melt-spun fibers using tensile strength testing In this example, fabrics made with PTFE-enhanced melt-spun fibers The resistance to ultraviolet (UV) degradation was investigated.

  In one study, the tensile break strength of nonwoven fibers, both before and after controlled exposure to ultraviolet (UV), in laboratory equipment to simulate UV degradation when used outdoors. Was tested. The industry standard test procedure SAE J1885 was used. This procedure is commonly used in the automotive industry to evaluate the light resistance of automobile interior fabrics. Procedures used in the automotive industry use a reference exposure of 226 kJ (eg Chrysler Group, Daimler Chrysler Corporation, Auburn Hills, MI 48326) or 488 kJ (eg Ford Motor Company, Dearborn, Michigan 48126).

  PTFE-reinforced fiber material with a concentration of 2.25% PTFE (prepared by incorporating 5% 45% PTFE masterbatch into the spinning melt) was used as the test material. A conventional fiber material prepared without PTFE was used as a control material. To determine the breaking force required to break the fiber, the tensile strength of the test and control samples was determined by applying a load to the fiber. Prior to UV irradiation, the sample was first tested. The forces required to break the fibers of the test and control samples were measured as 260 Newton and 270 Newton, respectively. These similar break force values indicate that PTFE-enhanced and non-enhanced fibers have comparable tensile strength.

The test and control samples are then run at various levels in a laboratory fatigue simulator (sold by Atlas Electric Model No. Ci4000 Weatherometer®, Atlas Electric Devices Company, 4114 N Ravenswood Ave, Chicago, IL 60613). Exposed to UV lamp radiation. In this simulator, xenon arc lamps up to twice the solar solar radiation intensity are used for accelerated weathering testing of specimens. The irradiation levels were 225, 490, 600, 800, and 1100 kJ / m ² . As the dose increased (ie at 800 kJ / m ² ), the control sample collapsed. However, the test sample maintained its structural integrity at all irradiations, including 1100 kJ / m ² . In the test and control samples exposed to 600 kJ / m ² irradiation, the breaking force was measured and found to be 169 newtons (lbs./sq.in) and 85 newtons, respectively. The decrease in tensile strength of the test and control samples due to UV irradiation was calculated to be about (260-169) / (260) = 35% and (270-85) / 270 = 68%, respectively. These results indicate that the addition of PTFE to the melt spun fiber improves the resistance to UV degradation by about a factor of two.

The tensile strength of the test sample after irradiation at 800 kJ / m ² and 1100 kJ / m ² was measured and found to be about 150 Newton and 135 Newton, respectively. FIG. 1 is a bar graph comparing the tensile strength (lbs./sq.in) of two samples as a function of dose. The irradiation dose data in the range of 0 kJ / m ^{2 to} 1100 kJ / m ² are shown. FIG. 2 is a bar graph showing the normalized intensities of test and control samples after irradiation with doses ranging from 225 kJ / m ^{2 to} 1100 kJ / m ² .

A separate study of radiation resistance was conducted in an independent fabric testing laboratory (IS LABS, Inc, 209A East Murphy Street Madison, NC 27025). In this laboratory, the tensile strength of PTFE-enhanced and control materials was measured using conventional textile industry procedures (SAE J1885). The measured parameters were breaking tenacity and elongation at break load. These parameters were measured before and after exposure under a fadeometer. After the test material was exposed to 488.8 kJ light in an Atlas Weatherometer apparatus, post-exposure measurement was performed. Samples from four different product categories were tested. Product categories 1 and 3 (labeled 1/150/100 and 1/150/50 control products, respectively) were sleeves knitted from yarn without PTFE additive, respectively. Product categories 2 and 4 (labeled 1/150/100 and 1/150/50 PTFE products, respectively) were sleeves knitted from PTFE-enhanced yarn. The consecutive numbers in the label refer to the number of filaments in the ply, denier, and yarn, respectively. Therefore, the label 1/150/100 refers to 1 ply, 150 denier, 100 filament yarn. The concentration of PTFE in the fibers augmented with 1/100/100 and 1/100/50 PTFE was both measured to be about 1.75%. In each product category, tube yarn (i.e. yarn not knitted or not woven into the fabric) and yarn unrolled from the product yarn were tested. Test results for various product categories are shown in Table 3.

  In Table 3, the first row of each product category refers to the calibration of the device or the standard measurement of tube yarn. The second row refers to the measurement of the unwound yarn of the sample before exposure to the test exposure in an Atlas Weatherometer device. Similarly, the third row refers to the measured value of the unwound sample sleeve in the Atlas Weatherometer device. The last measurement was repeated for three separate untwisted yarns for each product category.

  The dispersion seen in the test results for exposed and unexposed sleeve unwinded yarns may be related to the weaving or knitting structure of the textile fabric from which the sleeve was made. Overall, however, the results show that fibers with a certain concentration of PTFE additive are significantly stronger than fibers without PTFE additive.

Example 6: Improving the moisture management properties of fabrics made with PTFE-enhanced melt-spun fibers In this example, the ability to handle or manage moisture in fabrics made with PTFE-enhanced melt-spun fibers. investigated. The ability to handle or manage fabric moisture was determined by measuring the degree of capillary wicking in fabric strips soaked in aqueous solution. The water was finely colored so that when the fabric absorbed the water, the sucked-up waterfront could be visually observed. A colored aqueous solution was prepared by adding green food color to water in a beaker. The amount of dye added to the water was sufficient to raise the conductivity of the dye solution to about 1000 Mhos ± 100 Mhos.

  Two PTFE-reinforced fiber fabric strips (labeled PTFE-1 and PTFE-2) were tested. Two strips were tested with two control fabric strips (Control-1 and Control-2, respectively). Test and control fabric samples were cut into 1 inch wide and 8 inch long strips. The strips were conditioned for at least 4 hours at about 70 degrees Fahrenheit in a 65% ± 2% humidity atmosphere until just prior to testing. The strip of fabric was fixed vertically on the aqueous solution and the end was immersed in a beaker containing the colored aqueous solution. The bottom 1 inch of the test fabric strip was submerged in the dye solution. The stopwatch was activated when the bottom 1 inch of the fabric strip was submerged in a colored aqueous solution. Sucking up of colored water into the fabric strip was observed. The time taken for the tip of the wicking water to rise to a mark 1 inch, 2 inches, and 3 inches above the immersion level in the beaker was measured using a stopwatch. For each trial, two trials were performed for each fabric, using a new fabric strip.

Time measurements for various samples are listed in Table 4.

  The tip of the water wick in many examples did not rise evenly or consistently above the 3 ″ level, as also described in the comments section of Table 4. This means that under the test conditions, The strip of fabric indicates that it is saturated with water, at or near the 3 "mark, and is in a steady state. However, PTFE-enhanced fabrics consistently showed water uptake to levels of 1 "and 2" faster than the control fabric. For example, in the PTFE-1 strip, water was pumped to a level of 1 "in about 2 seconds, whereas in the Control-1 strip it was observed in about 6 to 8 seconds. Similarly, the PTFE-2 strip In the control-2 strip, water was drawn up to a level of 2 "in an average of about 28 seconds, whereas in the Control-2 strip, an average of about 30.5 seconds was observed. These test results indicate that fabrics made from PTFE-enhanced yarns have better moisture management properties than fabrics made from yarns that do not contain PTFE additives.

Example 7: Abrasion test of fabrics made with melt-spun fibers enhanced with PTFE In this example, the abrasion resistance of fabrics made with melt-spun fibers enhanced with PTFE was evaluated. Abrasion resistance was evaluated using the traditional Taber test method used to evaluate textile products. The method includes securing a piece of fiber fabric on a base plate of a test unit and repeatedly running a loaded wheel across the surface of the fiber fabric to reduce the fiber fabric. Before and after the test, the weight of the piece of fiber fabric was measured. Weight loss due to wear is an indicator of the wear resistance of the fabric.

  Sample fabrics made from PTFE-reinforced fibers were tested. The fabric was made with yarns enhanced with 1/150/100 PTFE. The sample was tested with a control fabric sample made with a conventional yarn without PTFE additive. These samples (labeled PTFE-3 and Control-3, respectively) were subjected to wear testing on commercially available equipment (Taber Abraser Model 503, sold by Taber Instruments Corporation, North Tonawanda, NY USA). Each fabric sample was weighed prior to testing. The fabric sample was then secured to the base plate of the device by vacuum. The wheel (H-10 size) was run for 200 cycles on the surface of the fabric sample. The wheels were loaded with a 500 g weight.

Overall visual observations revealed that the PTFE-enhanced fabric and the control fabric were both similar under the test conditions. Close examination of the test sample using a digital camera showed that the PTFE-enhanced fabric was smoother after abrasion than the control fabric. The fabric was weighed after abrasion to obtain a quantitative measure of the amount of abrasion. Each fabric type was tested four times. Test data for various fabric samples are listed in Table 5.

  The average weight loss (15%) in the PTFE-enhanced fabric samples was about three-quarters of the weight loss of the conventional control fabric (19%). These test results show that fiber fabrics made with yarns augmented with the appropriate amount of PTFE have better abrasion resistance than fabrics made from yarns without PTFE additives. Is shown.

In another series of tests, a sample of PTFE-enhanced fabric (PTFE-4) and a control sample (Control-4) based on General Motors standard method GM2794 for nonwoven carpet applications. A wear test was conducted. The test was carried out using H-18 size wheels that received a load of 1000 g. PTFE-4 samples for non-woven carpet applications have a PTFE content of approximately 2.25% (similar to the PTFE-1 and 2 samples above) and are manufactured from 18 dtex PET fibers containing approximately 1.5% pigment did. A control sample was made from unstretched PET fibers (80 dtex). The PTFE-4 sample was subjected to 2000 wheel cycle wear. The Control-4 sample was subjected to only 600 wheel cycles of wear, at which point Control-4 was deformed and rough enough to impede wheel movement. Both samples were weighed before and after the wear cycle. The test results are shown in Table 6.

  Test data shows that the PTFE-4 sample is less susceptible to wear than the Control-4 sample, despite the large number of wheel cycle wear (2000 vs. 600). Thus, PTFE-reinforced fibers are expected to be less likely to wear than conventional fibers for nonwoven carpet applications.

Example 8: Friction Coefficient Testing of Fiber Fabrics Made with PTFE-Enhanced Melt Spinned Fibers In this example, static and dynamic friction properties of fabrics incorporating PTFE-enhanced melt spun fibers are shown. The weight was changed and evaluated according to ASTM D-1894-00. An ALTEK friction coefficient test apparatus (sold by ALTEK Company, 245 East Elm Street, Torrington, CT 06790 USA) was used for this purpose. In general, the test apparatus was similar to the slide and pulley configuration described in Example 3 above. In the test procedure, a metal slide covered with fabric is slid over a steel platen covered with fabric. Pull the slide across the steel platen at a constant speed. The force required to start the sled (static) and the force required to maintain movement (dynamic) were measured using a strain gauge or force gauge. The value read by the gauge was divided by the weight of the slide to obtain the raw static and dynamic friction numbers. These numbers were converted to coefficient of friction by using a 2000 gram standard metal sled and referring to the calibration values of the instrument (COF = (reading × 2000) / slide weight).

  Two PTFE-reinforced fiber fabrics (labeled PTFE-5 and PTFE-6) were tested. Two fabrics were made from yarns reinforced with 1/100/50 and 1/150/100 PTFE, respectively. Samples from these PTFE-enhanced fiber fabric strips were tested along with samples from two control fabrics (labeled Control-5 and Control-6) made with conventional fibers.

For the friction test, a square piece (2.5 "x 2.5") was cut from the fabric and attached to the bottom surface of the slide (ie, a metal sled block). Another rectangular piece (4 "x 12") of the same fabric was attached to the surface of the steel surface plate. Each slide was slid or pulled over a steel platen at a speed of about 5 "/ min. At the beginning of the slide movement, the starting or first strain gauge reading was recorded as a reference for static friction. The average strain gage reading as the movable slide traveled 3 "was recorded as the dynamic friction criterion. Three different slide weights (obtained by adding 100 and 200 gram weights to the top of the slide) were used in the friction test. The weight of the three slides used, including the weight of the attached fabric, was about 184, 284, and 384 grams, respectively. Each fabric was tested four times for each slide weight. Tables 8 and 9 show the test data (strain gauge reading) and the coefficient of friction with the magnification changed (strain gauge reading × 2000 / slide weight). Tables 8 and 9 also show the percent improvement in COF over the control fabric for each PTFE-enhanced fabric tested.

  The data in Tables 8 and 9 are also shown in FIGS. 3 and 4 as comparative bar graphs. The data confirms that the addition of PTFE to the fiber reduces the coefficient of friction of the textile fabric.

FIG. 1 is a bar graph comparing the tensile strength of PTFE-enhanced fibers prepared according to the present invention and conventional fibers, both after exposure to radiation. FIG. 2 is a bar graph showing the relative tensile strength of the fibers of FIG. FIG. 3 shows the static and dynamic friction coefficients of fabrics made from PTFE-enhanced fibers prepared in accordance with the present invention and the static and dynamic friction coefficients of fabrics made with conventional fibers. It is a bar graph. FIG. 4 shows the static and dynamic coefficient of friction of another fabric made from PTFE-enhanced fibers prepared according to the present invention and the static and dynamic coefficient of friction of a fabric made of conventional fibers. It is the bar graph which compares.

Claims (20)

Preparing a melt of synthetic material;
Adding polytetrafluoroethylene (PTFE) material to the melt;
A method of producing fibers from a synthetic material comprising extruding a melt with added PTFE material through a spinneret to form fibers.   The method of claim 1, wherein adding the PTFE material to the melt comprises dispersing PTFE particles having a size of about 1 micron or less in the melt.   The method of claim 1, wherein adding the PTFE material to the melt comprises adding PTFE powder that can be dispersed to a submicron particle size.   The method of claim 1, wherein adding the PTFE material to the melt comprises adding an aqueous dispersion of PTFE powder that can be dispersed to a low micron particle size.   The method of claim 1, wherein adding the PTFE material to the melt comprises adding an organic solvent dispersion of PTFE powder that can be dispersed to a low micron particle size.   6. The method of claim 5, wherein the organic solvent dispersion of PTFE powder comprises about 20 wt% to about 60 wt% PTFE.   The method of claim 1, wherein adding the PTFE material to the melt comprises dispersing PTFE particles having a size that is smaller than the size of the spinneret channel.   The method of claim 1, wherein adding the PTFE material to the melt comprises introducing dispersible PTFE powder in the form of a pelletized masterbatch.   9. The method of claim 8, wherein the masterbatch comprises about 5% to about 60% PTFE.   The method of claim 1, wherein extruding the melt to which the fiber is a composite fiber and the PTFE material is added comprises forming a component of the composite fiber.   The method of claim 1, wherein the synthetic material comprises a material selected from the group consisting of polyester, nylon, polypropylene, polyethylene terephthalate, thermoplastic resin, and combinations thereof.   A woven fabric comprising fibers produced by the method of claim 1. An extrudate of a material selected from the group consisting of polyester, nylon, polypropylene, polyethylene terephthalate, thermoplastics, and combinations thereof; and a dispersion of PTFE particles in the extrudate:
Manufactured synthetic fibers containing.   The synthetic fiber of claim 13, wherein the dispersion of PTFE particles comprises PTFE particles having a size of about 1 micron or less.   The synthetic fiber of claim 13, wherein the dispersion of PTFE particles comprises PTFE particles having a size of about 1 micron or less.   14. A synthetic fiber according to claim 13, wherein the dispersion of PTFE particles is substantially uniformly distributed in the extrudate.   A woven fabric comprising the synthetic fiber according to claim 13.   A knitted fabric comprising the synthetic fiber according to claim 13.   A carpet comprising the fiber of claim 13.   A product comprising the fiber of claim 13.

Images