Filled cut-resistant fiber

Abstract: A fiber having increased cut resistance is made from a fiber-forming polymer and a hard filler having a Mohs Hardness Value greater than about 3. The filler is included in an amount of about 0.05% to about 20% by weight. In preferred embodiments, the fiber-forming polymer is poly(ethylene terephthalate) or a liquid crystalline polyester comprising monomer units derived from 6-hydroxy-2-naphthoic acid and 4-hydroxybenzoic acid. Preferred fillers include tungsten and alumina.

Description: Field of the Invention This invention relates to fibers made from polymers containing hard particles that have improved resistance to cutting. Background of the Invention Improved resistance to cutting with a sharp edge has long been sought. Cut-resistant gloves are beneficially utilized in the meatpacking industry and in automotive applications. As indicated by U.S. Patent Nos. 4,004,295, 4,384,449 and 4,470,251, and by EP 458,343, gloves providing cut resistance have been made from yarn which includes flexible metal wire or which consists of highly oriented fibers having high modulus and high tensile strength, such as aramids, thermotropic liquid crystalline polymers, and extended chain polyethylene. A drawback with gloves made from, yarn that includes flexible metal wire is hand fatigue with resultant decreased productivity and increased likelihood of injury. Moreover, with extended wear and flexing, the wire may fatigue and break, causing cuts and abrasions to the hands. In addition, the wire will act as a heat sink when a laundered glove is dried at elevated temperatures, which may reduce tensile strength of the yarn or fiber, thereby decreasing glove protection and glove life. Improved flexibility and comfort and uncomplicated laundering are desirable in cut-resistant, protective apparel. Therefore, there is a need for a flexible, cut-resistant fiber that retains its properties when routinely laundered. Such a fiber may be advantageously used in making protective apparel, in particular highly flexible, cut-resistant gloves. Polymers have been mixed with particulate matter and made into fibers, but not in a way that significantly improves the cut resistance of the fiber. For example, small amounts of particulate titanium dioxide has been used in polyester fiber as a delustrant. Also used in polyester fiber is a small amount of colloidal silicon dioxide, which is used to improve gloss. Magnetic materials have been incorporated into fibers to yield magnetic fibers. Examples include: cobalt/rare earth element intermetallics in thermoplastic fibers, as in published Japanese Patent Application No. 55/098909 (1980); cobalt/rare earth element intermetallics or strontium ferrite in core-sheath fibers, described in published Japanese Patent Application No. 3-130413 (1991); and magnetic materials in thermoplastic polymers, described in Polish Patent No. 251,452 and also in K. Turek et al., J. Magn. Magn. Mater. (1990), 83 (1-3), pp. 279-280. Various kinds of gloves have been made in which metal has been included in the fabrication of the glove to impart protective qualities to the glove. For example, U.S. Patent Nos. 2,328,105 and 3,185,751 teach that a flexible, X-ray shield glove may be made by treating sheets of a suitable porous material with a finely divided, heavy metal which may be lead, barium, bismuth or tungsten, or may be made from a latex or dispersion containing heavy metal particles. As illustrated by U.S. Patent No. 5,020,161, gloves providing protection against corrosive liquids have been made with a metal film layer. These gloves also do not appear to have significantly improved cut resistance. Thermotropic liquid crystalline cut resistant fibers including lesser amounts of a hard filler are described in EP 0599 231. Lyotropic liquid crystalline cut resistant fibers formed from p-phenylene diamine and terephthalic acid are provided in WO 95/31593. As known in the art, polymers formed from p-phenylene diamine and terephthalic acid are wetspun from a concentrated sulfuric acid solution. Accordingly, there is a need in the art to provide cut resistant fibers without the use of hazardous solvents such as sulfuric acid. Summary of the Invention A cut resistant fiber comprising (a) a fiber-forming polymer which is selected from either (i) an aromatic copolyamide comprising monomer units derived from terephthalic acid and at least two aromatic diamines or (ii) polyethylene having a molecular weight suitable for making extended chain polyethylene and (b) a hard filler distributed uniformly in said fiber, said fiber having a denier in the range of 1 to 50 dpf; said fiber having a Mohs Hardness Value greater than 3, said filler being present in an amount of 0.05% to 20% by weight, said filler being selected from the group consisting of a powder having an average diameter up to 20 microns, an elongated particle having an average length up to 20 microns, and mixtures thereof; said filler being included in sufficient quantity to improve the cut resistance by at least 20% compared with a fiber comprising said polymer without said filler as measured by the Ashland Cut Protection Performance Test. The cut-resistant fabric may optionally also include other polymeric fibers and/or reinforcing inorganic fibers, which may be ceramic, metal or glass. A new method of making a synthetic fiber or yarn more resistant to cutting with a sharp edge is also disclosed. The improved method comprises the step of including a hard filler having a Mohs hardness value greater than 3 in the synthetic fiber or yarn in sufficient quantity to improve the cut protection of the fiber or yarn by at least 20%, and preferably by at least 35%, as measured by the Ashland Cut Protection Performance Test. This is generally achieved by making a uniform blend of the molten polymer or polymer solution (dope) and then spinning the molten polymer or polymer solution (dope) into a fiber or yarn having improved cut protection performance. The preferred method is melt spinning. The fibers and yarns described above can be made into fabrics that have improved resistance to cutting using any of the methods that are currently used for making fibers and yarns into fabrics, including weaving and knitting. Both the fabrics and the methods of making cut-resistant fabrics and the resulting fabrics are new. Additionally, the cut-resistant fabrics are made into apparel with improved cut protection, such as gloves that are resistant to slicing with a knife. Detailed Description of the Invention As indicated above, a flexible cut-resistant fiber useful for the manufacture of protective apparel may be produced when a hard filler is included in the fiber. The fiber may be made of the fiber-forming polymer indicated above, and may be produced by any of the methods normally used in making fibers. The polymer preferably is melt processable, in which case, the cut-resistant fiber is typically made by melt spinning. For polymers that cannot be spun into fibers in the melt, wet spinning and dry spinning may also be used to produce fibers having improved cut resistance. Amorphous polymers, semi-crystalline polymers and liquid crystalline polymers may all be used in this invention. Of these, semi-crystalline and liquid crystalline polymers are preferred. The description of this invention is written with respect to fibers. The term fiber includes not only conventional single fibers and filaments, but also yarns made from a multiplicity of these fibers. In general, yarns are utilized in the manufacture of apparel, fabrics and the like. In one preferred embodiment of this invention, the fiber-forming polymer is an isotropic semi-crystalline polymer. "Isotropic" means polymers that are not liquid crystalline polymers, which are anisotropic. Preferably, the isotropic semi-crystalline polymer is melt processable; i.e., it melts in a temperature range which makes it possible to spin the polymer into fibers in the melt phase without significant decomposition. Polyethylene is a semi-crystalline polymer that may be used in this invention. Extended chain polyethylene, which has a high tensile modulus, is made by the gel spinning or the melt spinning of very or ultrahigh molecular weight polyethylene. Extended chain polyethylene already has a high cut resistance, but can be made even more cut resistant by adding particles to the fiber in accordance with this invention. All of the above polymers are known to be useful for making fibers and are all commercially available. isotropic poiymers that cannot be processed in the melt can also be used. Aromatic polyamides other than the polymer of terephthalic acid and p-phenylene diamine (e.g. polymers of terephthalic acid and one or more aromatic diamines) may be soluble in polar aprotic solvents, such as N-methylpyrrolidinone, and can be wet spun with added particles to yield cut-resistant fibers. Amorphous, non-crystalline, isotropic polymers, may also be filled and utilized in this invention. In another preferred embodiment, the fiber is made from a liquid crystalline polymer (LCP). LCPs give fibers with very high tensile strength and/or modulus. The liquid crystalline polymer may be processable in the melt (i.e., thermotropic), in which case melt spinning is the preferred method of making the fiber. However, polymers that cannot be processed in the melt may also be utilized. Thus, polymers that exhibit liquid crystalline behavior in solution can be blended with a hard filler and then can be wet or dry spun to yield cut-resistant fibers in accordance with the present invention. Aromatic polyamides that are soluble in polar aprotic solvents, such as N-methylpyrrolidinone, may also be spun into cut resistant fibers according to the present invention. See Example 10. These may not be liquid crystalline under some or all conditions, but they still yield high modulus fibers. Some may exhibit lyotropic liquid crystalline phases at some concentrations and in some solvents, but isotropic solutions at other concentrations or in other solvents. The preferred liquid crystalline polymers (LCPs) for use in this invention are thermotropic LCPs. These thermotropic LCPs include aromatic polyamides, and aliphatic-aromatic polyamides. Some of the aromatic groups may include substituents which do not react under the conditions of the polymerization, such as lower alkyl groups having 1-4 carbons, aromatic groups, F, Cl, Br and I. An important aspect of this invention is the discovery that a flexible, flexural fatigue-resistant and cut-resistant fiber may be made from a suitable polymer filled with a hard material that imparts cut resistance. The material may be a metal, such as an elemental metal or metal alloy, or may be nonmetallic. Generally, any filler may be used that has a Mohs Hardness value of about 3 or more. Particularly suitable fillers have a Mohs Hardness value greater than about 4 and preferably greater than about 5. Iron, steel, tungsten and nickel are illustrative of metals and metal alloys, with tungsten, which has a Mohs hardness value ranging from about 6.5 to 7.5 being preferred. Non-metallic materials are also useful. These include, but are not limited to, metal oxides, such as aluminum oxide, metal carbides, such as tungsten carbide, metal nitrides, metal sulfides, metal silicates, metal silicides, metal sulfates, metal phosphates, and metal borides. Other examples include silicon dioxide and silicon carbide. Other ceramic materials may also be used. Titanium dioxide and silicon dioxide are less preferred in semi-crystalline polymers. The particle size, particle size distribution, and the quantity of particles are all important parameters in obtaining good cut resistance while preserving fiber mechanical properties. A particulate form of the filler may be used, with a powder form being generally suitable. Flat particles (i.e. platelets) and elongated particles (needles) also can be utilized. For particles that are flat or elongated, the particle size refers to the length along the long axis of the particle (i.e. the long dimension of an elongated particle or the average diameter of the face of a platelet). Selection of an appropriate particle size depends on the processing and on the fiber diameter. The filter particles should be small enough to easily pass through the spinneret apertures. The particles should also be small enough that the fiber tensile properties do not appreciably deteriorate. For textile fibers, (i.e. fibers having a denier in the range of about 1.5 to about 15 dpf), the particles should be filtered or sieved in such a way that the particles larger than about 6 microns are excluded. In general, the particles should have an average diameter of less than about 20 microns, preferably in the range of about 0.05 to about 5 microns and in specific cases, about 0.2 to about 2 microns. For elongated particles, the long dimension should fit through the spinneret holes. Therefore, the average particle length of an elongated particle should be less than about 20 microns, and preferably is in the range of about 0.05 to about 5 microns and in specific cases, about 0.2 to 2 microns. The above is a general rule with respect to filled polymers in general. Further experimentation on hard particles in thermoplastic semicrystalline isotropic polymer indicates that at least for isotropic semicrystalline polymers and particularly for the most preferred embodiment (calcined alumina ), the particle size ranges that yield the best cut resistance are about 0.25 to about 10 microns, preferably about 1 to about 6 microns, and most preferably about 3 microns. The particle size should have a log normal distribution. A minor percentage of the hard filler is used. The amount is chosen to yield enhanced cut resistance without causing a significant loss of tensile properties. The cut resistance of the fiber or fabric made from the fiber is improved, as measured by the Ashland Cut Protection Performance test or other tests generally accepted in the industry. Preferably, the cut protection measured by these tests, and particularly the Ashland Cut Protection Test, will improve by at least 20%, more preferably by at least 35% and most preferably by at least 50%. Such tests as applied to fibers of liquid crystalline polymers are described in Example 3, and as applied to fibers of isotropic polymers and LCP's are described in Example 4. The tensile properties of the fiber (tenacity and modulus) should not decrease by more than about 50% and preferably will not decrease by more than about 25%. Most preferably, there will not be a significant change in tensile properties (i.e., less than about 10% decrease in properties). On a weight basis, the filler is present in an amount of about 0.05% to about 20%, preferably about 0.1% to about 20%. On a volume basis, the amount of filler is typically in the range of about 0.01% to about 3%, often is in the range of about 0.03% to about 1.5%, and in specific cases may be in the range of about 0.05% to about 1%, with the proviso that the amount of filler is within the weight ranges stated previously. Thus, for a dense filler, such as tungsten powder in poly(ethylene terephthalate), the amount of filler corresponding to the volume percents stated above but expressed on a weight basis, is typically in the range of about 0.14% to about 20%, preferably in the range of about 0.42% to about 20%, and more preferably in the range of about 0.7% to about 14%. For thermotropic liquid crystalline polymers, improved cut resistance can be obtained with about 0.07% to about 0.14% by volume of filler, corresponding to about 1% to about 2% by weight when the filler is tungsten. Further experimentation with isotropic semicrystalline polymers indicates that a better estimate of the ranges of particle amounts required to achieve high cut resistance is as follows: On a volume basis, the particle level concentration is preferably in the range of about 0.1 % to about 5% by volume, more preferably about 0.5% to about 3% by volume and most preferably about 2.1% by volume. For the most preferred embodiment (calcined alumina) these ranges on a weight basis are about 0.3% to about 14% (preferred), about 1.4% to about 8.5% (more preferred), and about 6% (most preferred). In accordance with the present invention, filled fibers are prepared from a filled resin. The filled resin is made by any of the standard methods for adding a filler to a resin. For example, for a thermoplastic polymer, the filled resin is conveniently prepared in an extruder, such as a twin screw extruder, by mixing the hard filler with molten polymer under conditions sufficient to provide a uniform distribution of the filler in the resin. The filler may also be present during the manufacture of the polymer or may be added as the polymer is fed into the extruder of fiber spinning equipment, in which case the blending and spinning steps are nearly simultaneous. Since the filler is distributed uniformly in the polymer melt, the filler particles are also typically distributed uniformly throughout the fibers, except that elongated and flat particles are oriented to some extent because of the orientation forces during fiber spinning. Some migration of the particles to the surface of the fiber may also occur. Thus, while the distribution of particles in the fibers is described as "uniform", the word "uniform" should be understood to include nonuniformities that occur during the processing (e.g., melt spinning) of a uniform polymer blend. Such fibers would still fall within the scope of this invention. Any size fiber may be made according to the present invention. In the manufacture of fabrics and yarns, the fiber will generally have a denier in the range of about 1 to about 50 dpf, preferably in the range of about 2 to about 20 dpf, and most preferably about 3 to about 15 dpf. For isotropic polymers, the most preferred range of fiber size is about 1.5 to about 15 dpf, and most preferably about 4 dpf. Cut-resistant monofilaments may also be made by including a hard filler. Monofilaments generally have a diameter of about 0.05 to about 2mm. The fibers are made by conventional fiber spinning processes. The preferred process is melt- spinning, but wet-spinning and dry-spinning may also be used. Cut-resistant fabric may be made by knitting, weaving, or other methods using a filled fiber in accordance with the present invention by using conventional methods and machinery. Such fabrics will have improved cut resistance in comparison with the same fabric made using fiber manufactured from the same polymer without a filler. Generally, the cut resistance will be improved when measured using tests generally accepted in the industry for measuring cut resistance (the Ashland Cut Protection test), and preferably will be improved by at least 20%, 35% or even 50%. Cut-resistant apparel may then be made from the cut-resistant fabric described above. For example, a cut-resistant safety glove designed for use in the food processing industries may be manufactured from the fabric. Such a glove is highly flexible and readily cleanable. The filled fiber resists flexural fatigue. Protective medical gloves may also be made using the cut-resistant fibers of this invention. These protective gloves can be sewn together from a fabric (woven, knit, or non-woven) that is made from the fibers and yarns taught herein. Alternatively, gloves can be knit directly from continuous yarns comprising the fiber, or pieces of fabric can be attached to gloves to protect the portions of the hand that are most at risk of being injured (e.g. palms or fingers). Cut-resistant fiber materials described herein can also be substituted for unfilled polymeric fibers in cut-resistant fabrics, gloves and the like made by conventional methods to give even greater cut resistance. Thus, a cut-resistant fabric utilizing the filled fiber taught herein that is further reinforced by including a reinforcing inorganic fiber such as metal, glass or ceramic fiber, in accordance with current technology should have even greater cut resistance than the same fabric using a conventional fiber. Example 1 Calcined alumina (Grade No. 1 from Agsco), having an average particle size of about 2 microns, was blended at a level of 6% by weight of the polymer in a spinning dope which contained aramid at a level of 6% by weight, available under the name TREVAR™, dissolved in N-methylpyrrolidinone (NMP). The aramid is a copolymer of terephthalic acid with the following three diamines in a 2:1:1 ratio: 3,3'-dimethylbenzidine, p-phenylenediamine, and 1,4-bis-(4-aminophenoxy)-benzene. The aramid was wet spun and then drawn at 380° with a draw ration of 11:1 to yield a yarn having a denier of 4 dpf, tenacity 22 gpd, and modulus 675 gpd. A control sample of unfilled aramid was also wet spun into a yarn having a denier of 5.3 dpf, tenacity 26 gpd, and modulus 711 gpd. Comparative samples of PET containing 6% by weight alumina (same alumina as above) were also run. The yarns were knit into gloves, and the cut resistance of fabric from the gloves was tested. The cut resistance values are tabulated in Table 8. The cut resistance of the filled aramid is clearly the highest. Example 2 Calcined alumina (Grade No. 1 from Agsco, average particle size 2 microns) is compounded at a level of 7 weight % with high molecular weight polyethylene having a weight average molecular weight of about 150,000. This polyethylene is sold commercially in fiber form as an extended chain polyethylene under the CERTRAN® trademark. The filled polymer is melt spun to yield a filled high modulus fiber after drawing at a 20:1 ratio. The yarn has a CPP value that is improved by about 45%. The spinning process is taught in US Patent Nos. 4,287,149; 4,415,522; and 4,254,072, incorporated herein by reference. Similarly, extended chain polyethylene fiber containing filler particles is also made by the gel spinning of particle filled ultrahigh molecular weight polyethylene by the process taught in US Patent Nos. 4,356,138, 4,413,110, and 4,663,101 which are incorporated herein by reference. It is to be understood that the above described embodiments of the invention are illustrative only and that modification throughout may occur to one skilled in the art. Accordingly, this invention is not to be regarded as limited to the embodiments disclosed herein. OSY CPP CPP/OSY TREVAR Aramid (unfilled) 3.7 379 102 TREVAR Aramid plus Alumina 4.6 951 205 PET plus Alumina 4.3 516 120 Thus, the cut-resistant fiber as described above has an improved cut resistance by at least 20 % compared with a fiber comprising said polymer without said filler. The previously mentioned cut-resistant fiber comprises a hard filler having a Mohs Hardness Value greater than 5. The hard filler is present in an amount of 0.01 % to 3 % by volume, preferalby in an amount of 0.03 % to 1.5 % by volume, and more preferably in an amount of 0.05 % to 1 % by volume. The cut-resistant fiber as recited above comprises said hard filler which is selected from the group consisting of a powder having an average diameter in the range of 0.05 to 5 microns, an elongated particle having an average length in the range of 0.05 to 5 microns, and mixtures thereof. Preferably said hard filler is selected from the group consisting of a powder having an average diameter in the range of 0.2 to 2 microns, an elongated particle having an average length in the range of 0.2 to 2 microns, and mixtures thereof. The mentioned hard filler is present in an amount of 0.01 % to 3 % by volume. Preferably said hard filler is present in an amount of 0.03 % to 1.5 % by volume; whereby said hard filler is selected from the group consisting of a powder having an average diameter in the range of 0.05 to 5 microns, an elongated particle having an average length of 0.05 to 5 microns, and mixtures thereof. Preferably said hard filler is present in an amount of 0.05 % to 1 % by volume; whereby said hard filler is selected from the group consisting of a powder having an average diameter in the range of 0.2 to 2 microns, an elongated particle having an average length of 0.2 to 2 microns, and mixtures thereof. The mentioned hard filler is a metal or metal alloy. Said hard filler is a metal or metal alloy selected from the group consisiting of iron, nickel, stainless steel, tungsten, and mixtures thereof. The hard filler is selected from the group consisting of metal oxides, metal carbides, metal nitrides, metal sulfides, metal silicates, metal silicides, metal sulfates, metal phosphates, metal borides, and mixtures thereof, except that said hard filler is not titanium dioxide or silicon dioxide. The fiber-forming polymer is a liquid crystalline polymer in the cut-resistant fiber as recited above. The fiber-forming polymer is a lyotropic liquid crystalline polyamide comprising monomer units derived from terephthalic acid and 1,4-phenylene-diamine. The fiber-forming polymer is a thermotropic liquid crystalline polymer. The thermotropic liquid crystalline polymer comprises terephthalic acid. The cut-resistant fiber as recited above, wherein said hard filler is a metal or metal alloy. The cut-resistant fiber as recited above, wherein said hard filler is a non-metal selected from the group consisting of metal oxides, metal carbides, metal nitrides, metal sulfides, metal silicates, metal silicides, metal sulfates, metal phosphates, metal borides, and mixtures thereof. The cut-resistant fiber as recited above, wherein said fiber-forming polymer is a thermotropic liquid crystalline polymer. The cut-resistant fiber as recited above, wherein said hard filler is selected from the group consisting of iron, steel, nickel, tungsten, and mixtures thereof. The cut-resistant fiber as recited above, wherein said hard filler is tungsten in an amount of 1 % to 2 % by weight. The cut-resistant fiber as recited above, wherein said hard filler is selected from the group consisting of metal oxides, metal carbides, metal nitrides, metal sulfides, metal silicates, metal silicides, metal sulfates, metal phosphates, metal borides, and mixtures thereof. The cut-resistant fiber as recited above, wherein said hard filler is alumina. The cut-resistant fiber as recited above, wherein said fiber-forming polymer is a melt-processable isotropic semicrystalline polymer. The cut-resistant fiber as recited above, wherein said hard filler is selected from the group consisting of metals and metal alloys. The cut-resistant fiber as recited above, wherein said hard filler is selected from the group consisting of metal oxides, metal carbides, metal nitrides, metal sulfides, metal silicates, metal silicides, metal sulfates, metal phosphates, metal borides, and mixtures thereof, except that said hard filler is not titanium dioxide or silicon dioxide. The invention also comprises a method of making a cut-resistant fabric comprising the steps of (a) making a uniform blend of a fiber-forming polymer and 0.05 % to 20 % by weight of a hard filler having a Mohs Hardness value greater than 3; (b) spinning said uniform blend into a fiber or yarn by a method selected from the group consisting of melt spinning, wet spinning, and dry spinning; and (c) fabricating said fiber or yarn into fabric having cut resistance improved by at least 20 % as measured by the Ashland Cut Protection Performance Test in comparison with the same fabric made from said fiber-forming polymer without said hard filler. The method as recited above, wherein said uniform blend comprises 0.01 % to 3 % by volume of a hard filler selected from the group consisting of a powder having an average diameter in the range of 0.05 microns to 5 microns, an elongated particle having an average length in the range of 0.05 microns to 5 microns, and mixtures thereof, wherein the cut resistance is improved by at least 20 % as measured by the Ashland Cut Protection Performance Test in comparison with the cut resistance of the same fabric without said hard filler. The method as recited above, wherein said uniform blend comprises 0.03 % to 1.5 % by volume of a hard filler selected from the group consisting of a powder having an average diameter in the range of 0.2 microns to 2 microns, an elongated particle having an average length in the range of 0.2 microns to 2 microns, and mixtures thereof. The method as recited above, wherein said fiber-forming polymer is a liquid crystalline polyer. The method as recited above, wherein said fiber-forming polymer is a lyotropic liquid crystalline polyamide. The method as recited above, wherein said fiber-forming polymer is a thermotropic liquid crystalline polymer. The method as recited above, wherein said hard filler is a metal or metal alloy. The method as recited above, wherein said hard filler is selected from the group consisting of iron, steel, tungsten, nickel and mixtures thereof. The method as recited above, wherein said hard filler is tungsten in an amount of 1 % to 2 % by weight. The method as recited above, wherein said hard filler is a non-metal selected from the group consisting of metal oxides, metal carbides, metal nitrides, metal sulfides, metal silicates, metal silicides, metal sulfates, metal phosphates, metal borides, and mixtures thereof. The method as recited above, wherein said fiber-forming polymer is a melt-processable isotropic semi-crystalline polymer. The method as recited above, wherein said fiber-forming polymer is a melt-processable semicrystalline polymer. The method as recited above, wherein said hard filler is a metal or metal alloy. The method as recited above, wherein said hard filler is tungsten in an amount of 10 % by weight. The method as recited above, wherein said hard filler is a non-metal selected from the group consisting of metal oxides, metal carbides, metal nitrides, metal sulfides, metal silicates, metal silicides, metal sulfates, metal phosphates, metal borides, and mixtures thereof. The method as recited above, wherein said hard filler is alumina. The invention also encompasses a cut-resistant fabric made by the methods cited above. A cut-resistant fiber as recited above, wherein the cut-resistance of said fiber is improved by at least 35 % compared with a fiber comprising said polymer without said filler. A cut-resistant fiber as recited above, wherein said fiber has a denier in the range of 2 to 20 dpf, preferably a denier in the range of 3 to 15 dpf. The cut-resistant fabric made by the methods cited above. A cut-resistant fiber as recited above, wherein said fiber-forming polymer is an isotropic melt-processable polymer, said filler has an average particle size in the range of 0.25 microns to 10 microns, and said filler is included in an amount of at least 0.1 % by weight. A cut-resistant fiber as recited above, wherein the cut resistance of said fiber is increased by at least 35 % compared with a fiber comprising said polymer without said filler. A cut-resistant fiber as recited above, wherein the average particle size of said hard filler is in the range of 1 to 6 microns. A cut-resistant fiber as recited above, wherein said hard filler is included in said fiber in an amount of 0.1 % to 5 % on a volume basis. A cut-resistant fiber as recited above, wherein said hard filler is included in an amount of 0.5 % to 3 % on a volume basis. A cut resistant fiber as recited above, wherein said isotropic melt-processable polymer is polyolefin. A cut resistant fiber as recited above, wherein said hard filler is calcined aluminum oxide. A cut resistant fiber as recited above, wherein said hard filler is selected from the group consisting of iron, steel, nickel, tungsten, and mixtures thereof. The cut-resistant fiber as recited above, wherein said hard filler is calcined aluminum oxide. The cut-resistant fiber as recited above, wherein said hard filler is selected form the group consisting of iron, steel, nickel, tungsten, and mixtures thereof. The method of making a cut-resistant fabric as recited above, wherein said fiber-forming polymer is polyethylene. The method of making a cut-resistant fabric as recited above, wherein the average particle size of said hard filler is in the range of 1 to 6 microns. The method of making a cut-resistant fabric as recited above, wherein said hard filler is included in an amount of 0.5 % to 3 % on a volume basis. The method of making a cut-resistant fabric as recited above, wherein said hard filler is calcined aluminum oxide. The method of making a cut-resistant fabric as recited above, wherein said hard filler is selected from the group consisting of iron, steel, nickel, tungsten, and mixtures thereof. A method of making a fiber having increased cut resistance, comprising the steps of: (a) making a uniform blend comprising a fiber-forming polymer and 0.05 % to 20 % by weight of a hard filler having a Mohs hardness value greater than 3, said filler having an average particle size up to 20 microns; and (b) spinning said uniform blend into a fiber having a denier in the range of 1 to 50 dpt, said fiber having a cut resistance that is increased by at least 20 % compared with a fiber comprising said polymer without said filler, as measured by the Ashland Cut Protection Performance Test. The method recited above, wherein said blend comprises 0.01 % to 3 % by volume of said hard filler, said hard filler having an average particle size in the range of 0.05 to 5 microns. The method as recited above, wherein said fiber-forming polymer is selected from the group consisting of liquid cyrystalline polymers and semi-crystalline polymers. The method as recited above, wherein said hard filler is selected from the group consisting of tungsten and aluminum oxide.

Claims: A cut resistant fiber comprising (a) a fiber-forming polymer which is selected from either (i) an aromatic copolyamide comprising monomer units derived from terephthalic acid and at least two aromatic diamines or (ii) polyethylene having a molecular weight suitable for making extended chain polyethylene and (b) a hard filler distributed uniformly in said fiber, said fiber having a denier in the range of 1 to 50 dpf; said fiber having a Mohs Hardness Value greater than 3, said filler being present in an amount of 0.05% to 20% by weight, said filler being selected from the group consisting of a powder having an average diameter up to 20 microns, an elongated particle having an average length up to 20 microns, and mixtures thereof; said filler being included in sufficient quantity to improve the cut resistance by at least 20% compared with a fiber comprising said polymer without said filler as measured by the Ashland Cut Protection Performance Test. A cut-resistant fiber as recited in claim 1, wherein said fiber-forming polymer is an aromatic copolyamide comprising monomer units derived from terephthalic acid and two or more aromatic diamines. A cut-resistant fiber as recited in claims 1 or 2, wherein said aromatic copolyamide is soluble in a polar aprotic solvent. A cut-resistant fiber as recited in any one of claims 1 to 3, wherein said aromatic diamines are p-phenylenediamine, 3,3'-dimethylbenzidine, and 1,4-bis-(4-aminophenoxy)-benzene. A cut-resistant fiber as recited in claim 1, wherein said fiber-forming polymer is polyethylene having a molecular weight suitable for making extended chain polyethylene. A cut-resistant fiber as recited in claims 1 to 5, wherein said filler has an average particle size in the range of 0.25 microns to 10 microns and is included in an amount of 0.1 % to 5% by volume. A cut-resistant fiber as recited in any one of claims 1 to 6, wherein said filler is calcined alumina. A cut-resistant fiber as recited in any one of claims 1 to 6, wherein said filler is selected from the group consisting of iron, steel, nickel, tungsten and mixtures thereof. A cut-resistant fiber as recited in any one of claims 1 to 8, wherein said fiber is made by a method selected from gel spinning and melt spinning. A glove comprising the cut-resistant fiber as recited in any of claims 1 to 9.

Inventors: CARTER MICHELLE C, CLEAR WILLIAM F, FLINT JOHN A, GILLBERT-LAFORCE GUNILLA E, HAIDER MOHAMMED I, KAFCHINSKI EDWARD R, LANIEVE HERMAN L, OAKLEY ETHERIDGE O JR, SANDOR ROBERT B, THOMPSON SCOTT W, CARTER, MICHELLE C., CLEAR, WILLIAM F., FLINT, JOHN A., GILLBERT-LAFORCE, GUNILLA E., HAIDER, MOHAMMED I., KAFCHINSKI, EDWARD R., LANIEVE, HERMAN L., OAKLEY, ETHERIDGE O., JR., SANDOR, ROBERT B., THOMPSON, SCOTT W.
Applicants: HONEYWELL INT INC, HONEYWELL INTERNATIONAL, INC.
Application year: 1997
Main classification: D01F1
IPC codes: D04H3, D01F1, A41D31, D01F6, D01F8, D04H1