MXPA97009886A - Thermoplastic fiber filled resistant to co - Google Patents

Abstract

A fiber having increased shear strength is made from an isotropic polymer and a hard filler having an average particle size on the scale of about 0.25 microns to about 10 microns and having a hardness value of Mohs of more than 3, the hard filler is included in an amount of at least about 0.1% by weight, the preferred isotropic polymer is a polyethylene terephthalate, the preferred filler is a polyethylene terephthalate, the preferred filler is calcined alumina

Description

THERMOPLASTIC FIBER FILLED WITH RESISTANT CUTTING RELATED REQUEST This request is + a related to the request for E.U.fl. commonly assigned No. 00 / 243,344, filed on May 16, 1994, even pend eni, and two divisional applications thereof.

FIELD OF THE INVENTION This invention relates to fibers made to par + ir of thermoplastic polymers containing hard fillers having improved cut resistance.

BACKGROUND OF THE INVENTION Improved resistance to cuts with a sharp edge has been sought. Cut-resistant gloves are used beneficially in the meat packing industry and in automotive applications. As indicated by the US patents. A. Nos. 4,004,295, 4,384,449 and 4,470,251, and EP 458,343, gloves that provide resistance to cuts have been made from yarn that includes flexible metal wire or consisting of fibers of high tensile strength. A disadvantage with the gloves made of yarn that included flexible metal wire * .- s that is tired for the hands with resultant reduced producti and probability of dari? increased. In addition, with extensive use and bending, the wire can be fatigued and break, causing cuts and friction to the hands. In addition, the wire will act as a heat sink * when a washed glove is dried at elevated temperatures, which can reduce the tensile strength of the fiber or fiber, thus reducing glove protection and glove life. The oriented f-ibrns .11 with high modulus and high tensile strength have better cut resistance than conventional semi-standard polymers. Examples of these highly oriented polymers include pol ararnides, liquid crystalline ternary peak polymers and extended chain polyethylene. These also have disadvantages that limit their usefulness, including the loss of properties at the temperatures found in a dryer (pol etijeno), poor resistance to bleaching (poiiararnidas), poor comfort and cost or .. Improved flexibility and comfort are desired dad and Uncomplicated laundry in protective clothing, resistant to cuts. Therefore, a flexible, cut resistant fiber that retains its properties when washed routinely is needed. Said pound can be used advantageously to make protective gloves, in particular highly flexible, resistant to cuts.

Polymers have been mixed with particulate matter and made into fibers, but not in a manner that significantly improves the fiber's resistance to cuts, except for the crystalline polymers thermotropic liquids. For example, small amounts of particle titanium dioxide have been used in polyester fiber as an opacifier. A small amount of silicon dioxide and colloid LO is also used in the polyester fiber, which is used to improve the luster. Magnetic materials have been incorporated into the fibers to produce magnetic fibers. Examples include: rare cobalt / alkaline metal compounds in opiate fibers, as in Japanese Patent Application Laid-open No. 55/098909 (19H0); cobalt interrelationships / rare alkali metals or strontium ferrite in core fibers, described in Japanese Patent Application Laid-open No. 3- 130 13 (1991); and magnetic materials in thermoplastic polymers, described in Polish Patent No. 251,452 and also in K. Turek, et al., J. Magn. r-lagn ater (1990), 83 (1-3), pp. 279-280.

BRIEF DESCRIPTION OF THE INVENTION Fibers and yarns made from melt-processable isotropic polymers can be made more resistant to cutting with a sharp edge by including a hard filler that is preferably evenly distributed through the fiber. The hard filler has a Mohs hardness value greater than approximately ") and is present in an amount of about 0.5% by weight.The average particle size is in the range of approximately 0.25 microns to about The fiber has an improved cut resistance compared to a fiber made with the same polymer without the hard filler * This improvement is at least about 20% when measured by the performance test in the protection At the Ashland cut, a new method for making a fiber or yarn is also described.-? nt ethical rnas resistant to cuts with a sharp edge. The method comprises the steps of making a uniform blend of a melt-processable sotrop co polymer and a hard filler * having a Mohs hardness value greater than 3 and then spinning the polymer in the melt phase to form a fi ber or yarn. which has its improved cut resistance by at least about 20% when measured by the Ashland cut protection performance test. The fibers and yarns described above can be made into fabrics having improved cut resistance using any of the methods currently used to make fibers and yarns into fabrics, including knitting and knitting. The fibers and yarns can also be made in non-woven fabrics having improved cut resistance. Both the fabrics and the methods to make fabrics resistant to cuts and the resulting fabrics, are novel.

DETAILED DESCRIPTION OF THE INVENTION As noted above, a flexible fiber resistant to cuts useful for the manufacture of protective clothing can occur when a hard filler is included in the fiber. The fiber is made from a polymer so + rop co. The term "isotrop co" means polymers that are not crystalline and liquid. The polymer can preferably be processed by fusion; that is to say *, that merges in a temperature scale that makes it possible to spin the polymer to form * fibers in the fusion phase without significant decomposition. The preferred method for making the fiber is by melt spinning. Preferred isotropic polymers are crystalline serums. Sernicpstalin polymers that will be highly useful include polyalkylene terephthalates, polyalkylene naphthalates, polyarylene sulphides, aliphatic polyaryndes, and a? Fat? Cas-ar * ornat? casts, and polyesters comprising monomer units derived from cyclohexanedirithanol and terephthalic acid and polyolefms, including polyethylene and polypropylene. Examples of specific crystal polymers include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyphenylene sulfide, poly terephthalate, 4-cyclohexanedirnithanol, wherein 1,4-c-chlorhexanod-methanol is a mixture of cis and trans isomers, nylon-6 and nylon-66, polyethylene and polypropylene. These polymers are known to be useful for making fibers. The preferred sernicrist almo polymer is polyethylene terephthalate. Polymers that can not be * processed by melting can also be stained with hard particles, such as, for example, cellulose acetate, which are typically spun dry using acetone as a solvent, or a polyaramide, such as the terephthalic acid polymer and p-faith ilondiamine, which is spun in water and dried by * jet from a concentrated solution of sulfuric acid. The hard particles can be incorporated into the spinning processes for these polymers to obtain the filled fibers. Non-crystalline and amorphous polymers can also be filled and used by the melt-spinning process such as the copolymer and isophthalic acid, terephthalic acid and bisphenol A polyaplate. An important aspect of this invention is the discovery that a fiber resistant to cutting and flexible can be made from a suitable polymer filled with a hard material that imparts shear strength. The material can be a metal such as an elemental metal or metal alloy or it can be non-metallic. Generally, any * Filler can be used that has a Mohs hardness value of about 3 or more. Particularly suitable fillers have a hardness value of Mohs greater than about 4 and preferably greater than about 5. Iron, steel, tungsten and nickel are illustrative metals and metal alloys, with tungsten being preferred, which has a Mohs value varying from Approximately 6.5 to 7.5. Non-metallic materials are also useful. These include, but are not limited to, metal oxides, such as aluminum oxide and silicon dioxide, metal carbides, talons such as silicon carbide and tungsten carbide, metal nitride, metal sulphide, metal silicate. , metal silicones, metal sulfates, metal phosphates and metal borides. Other ceramic materials can also be used. Those that are preferred are ol oxy or Luirumo and especially the calcined aluminum oxide. Titanium dioxide is less preferred in general. The particle size and the particle size distribution are important parameters to obtain good cut resistance, while preserving the mechanical properties of the fiber. In general, the hard filler should be in the form of particles, a powder form generally being adequate. Flat particles (ie platelets) and elongated particles (needles) also work well. The average particle size is generally in the range of about 0.25 to about 10 microns. Preferably, the average particle size is on the scale of approximately 1 to 6 micras. The average particle size that is most preferred is about 3 microns. For particles that are flat (ie platelets) or elongated, the particle size refers to the length along the longitudinal ee of the particle (i.e. the length dimension of an elongated particle or the average diameter of the face). of a platelet). The particles should exhibit * preferably a normal distribution. To manufacture textile fibers (ie, fibers having a denier * on the scale of approximately 1.5 to 15 dpf), the particles must be filtered or sieved in such a way that particles of about 6 microns are excluded. A smaller percentage of the hard filler is used. The amount is chosen to produce improved shear strength without causing a significant loss of tensile strength properties. Desirably, the cut resistance of the fiber or fabric made from the fiber will show improvements of at least about 20% using the Ashland cut protection performance test. Preferably, the cut resistance will improve by at least about 35%, and preferably will improve by at least about 50% compared to a fiber made from the polymer ism but without the filler. The tensile strength properties of the fiber (toughness and modulus) preferably will not decrease by more than about 50% and preferably will not decrease by more than about 25%. Most preferably, there will be no change if nificativo in the properties of resistance to the tension (it is dedr, less than approximately 10% of decrease in the properties). On a weight basis, the filler must be present in an amount of at least about 0.1%. The upper Limit of the Lumberjack is determined principally by the effect on tensile strength properties, but levels above about 20% are generally less desirable. On a volume basis, the concentration of the particle level is preferably in the range of about 0.1% to about 5% by volume, preferably about 0.5% to about 3% by volume and more preferably about 2.1% by volume. volume. For the preferred embodiment (calcined alumina in PET), these scales on a weight basis are from about 0.3% to about 14% (preferred), approximately 1.4% to about R.5% (most preferred) and about 6% ( more preferred). In accordance with the present invention, the filler fibers are prepared from a ream with filler. The filler res * is done by any of the normal methods to add a filler to a res. For example, for a melt processable isotropic polymer, the ream with filler is conveniently prepared in an extruder, mixing the hard filler with the molten polymer under conditions sufficient to provide a uniform distribution of the filler in the resin, such as by mixing with an extruder. of twin worms. 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 the fiber spinning equipment, in which case the mixing and spinning steps are almost simultaneous. filler * is distributed uniformly in the polymer melt, the particles of! Fillers are also typically uniformly distributed along the fibers, except that the elongated and flat particles are oriented to some degree due to the orientation forces during the spinning of the fiber. Some migration of the particles to the surface of the fiber may also occur. In this case, although the distribution of the particles in the fibers is described as "uniform", the word "uniform" should be understood to include no or iforms that occur during processing (eg, melt spinning) of a uniform polymer mixture. Said fibers would still fall within the scope of this invention. A fiber of any size can be made in accordance with the present invention. In the manufacture of fabrics and yarns, the fiber will generally have a denier on the scale of about 1 to about 50 dpf, preferably on the scale of about 1.5 to about 15 dpf, and most preferred of about * 4 dpf. Cut-resistant mono-clamps can also be made by including a hard filler. The monofilaments generally have a diameter of about 0.05 to approximately 2 mm. The fibers are made by conventional fiber spinning processes. The preferred process is melt spinning, but wet spinning and dry spinning can also be used. The above description is written with respect to fibers. The term fiber includes not only conventional simple fibers, but also yarns made from an ultiplicity of these fibers. In general, threads are used in the manufacture of costumes, fabrics and fabrics. The cut resistant fabric can be made using a paper filled in accordance with the present invention using conventional methods, such as knitting, stitching, and conventional equipment. You can also make non-woven fabrics. Said fabrics will have improved cut resistance compared to the same made using fiber made from the same polymer without a filler. The cut resistance of the fabric will improve by at least about 20% when tested by the Ashland cut-off test. Preferably, the cut resistance will improve by at least about 35% and preferably will improve at least one%. E.1 Cut resistant clothing can then be made from the cut resistant fabric described above. For example, a safe cut resistant glove designed for use in the food processing industries can be manufactured from the fabric. This glove is highly flexible and can be cleaned quickly, being resistant to bleaching with chlorine and the heat of a dryer. Protective medical gloves can also be made using cut resistant fibers for invention. Other uses of fabrics and inonofi laments include side curtains and waxed for trucks, equLpa or soft side, commercial carpets, things that can be inflated, fuel cells, apiastable packaging, airline cargo curtains, hose covers, aprons resistant to cuts for use in metal packaging, garlic clove, ote.

EXAMPLE 1 Polyethylene terephthalate fibers incorporating tungsten powder filler are described below. Tungsten has a Mohs hardness value of approximately 6.5 to 7.5. Tire grade polyethylene terephthalate (PET), having an intrinsic viscosity of about 0.95 when operating in o-chloro phenol, was obtained from Hoechst Celanese Corporation, Somerville, New Jersey in the form of pellets. A master filler is made by mixing the polymer with 10% tungsten powder on a weight basis in a twinworm extruder. Tungsten has an average particle size of about 1 miera. The polymer and tungsten pellets are dried before mixing. The masterbatch is mixed with additional PET in a twinworm extruder to produce mixtures having 1% and 4% tungsten on a weight basis. The samples are spun by fusion by forcing the molten mixture first through a filter bag and then through a spinner. The lulo is subsequently extracted from a feed roller heated to 9 ° C, then extended over a heated shoe, and finally subjected to a 2% relaxation at? 25 ° C. The yarn is twisted to test the properties. The data is summarized in Table L. One of the fibers loaded with 10% tungsten is also analyzed for tungsten to ensure that the filler is not filtered. The analysis of the fiber shows approximately 8.9% by weight of tungsten in the fiber. Properties of resistance to tension. Tenacity, elongation and modulus are measured using the ASTM D-3T22 test method. Resistance to cuts., The fiber is first woven in fabric for the test of resistance to cuts. The yarn area density in the fabric is measured in grains / rnetro '* 2 (GMC in tables i and 2). The cut resistance of the fabric is then measured using the Ashland Cutting Performance Protection ("CPP") test. The test was carried out at TRI / Environnental, Inc., 9063 flee Cave Road, Aust m, Texas 78733-6201. In the test, the fabric sample is placed on the flat surface of a mandrel. A series of tests is carried out where a razor loaded with a variable weight is pulled along the fabric until the cloth is completely cut. The distance the knife travels through the fabric is measured until the knife cuts through the fabric completely. The point at which the knife cuts through the cloth is the point at which electrical contact is made between the mandrel and the knife. The distance required to make the cut is outlined in a graph or a function of the load on the knife. The data is numbered and delineated to cut distances ranging from about 0.P62 crn to about 4572 crn. The resulting graph is approximately a straight line. An idealized straight line is drawn or calculated at the points on the graph, and the weight required to cut through the fabric after one centimeter of travel along the fabric becomes the graph or is calculated by analysis of regression. The interpolated values of the weight required to make a cut after a centimeter of stroke of the knife along the fabric are shown in tables 1 and 2 as "CPP", an abbreviation for Court Protection Performance. Finally, for purposes of comparing the data for different fabric sample thicknesses, the CPP value is divided by the thickness of the fabric (GMC) to compensate for variations in the thickness of the fabric. This value is shown as CPP / GMC in tables 1 and 2.

EOEMPLE 2 In these experiments, the PET fiber samples are filled with alumina powder, which is sold commercially or the trademark MICROPOLISH * TI as an abrasive for polishing. Two different alumina powders are used having average particle sizes of about 0.05 microns and about 1.0 microns. Both are obtained as de-agglomerated powders from Duehler, Ltd., Waul-egan Road, Lake Buff, Illinois 60044. The 0.05 micron alumina is gamma alumina with a cubic crystal structure and a Mohs hardness value of 8. The material of 1.0 miera is alpha alumina that has a hexagonal crystal structure and a Mohs hardness value of 9. The two alumina powders are mixed with PET using the rnLsrno m as in example 4 to produce PEI samples with alumina-containing filler at levels around 0.21%, 0.86%, 1.9% and 2.1% by weight. Measurements of fiber properties and cut resistance are made using the same methods as in example 1. The data is presented in table 2. The data in tables 1 and 2 show that there is an improvement in the resistance to cuts of at least about 10% -20% at all levels of filler used. Both data series incorporate filler into the fiber at levels of about 0.07% to about 0.7% on a volume basis. The properties of the fiber do not seem to degrade signi icantly with these quantities and sizes of particles.

EXAMPLE 3 A series of experiments was conducted using tungsten particles of various dif- ferent particle sizes (0.6 - 1.6 microns) as fillers in PET at concentrations of 0.4 - 1.2% by volume. The PFT with tungsten filler was Lo in thread, which was subsequently woven into cloth for testing. Once the cut resistance was tested by the Ashland Court Protection Test, using the modified procedure described later. The values of CPP were divided by the area densities of the fabric to correct the fact that the tests were carried to < Aboon different densities of tola, the data are presented in table 3.

Cutting protection performance (CPP) The Ashland CPP Test was carried out as described at the end of experiment 1, but a calibration against a standard with a known CPP value was used to correct the results. The calibration standard was neoprene of .15 ^ 48 crn, style NS-5550, obtained from FAIRPRENE, 85 Mili Plain Road, Fairpeld, CT 06430, which has a CPP value of 4UÜ grams. The value of CPP was determined for this pattern at the beginning and end of a series of tests, and an average normalization factor was calculated that would give the measured CPP value of the standard to 400 grams. The normalization factor was then used to correct the measured data for that series of tests. Also, when calculating the value of CPP, a graph of the logarithm of the distance required to cut the fabric against the load on the razor was used, since it was more linear.

EXAMPLE 4 A series of experiments was conducted using calcined aluminum oxide as the filler for the fiber. The experiments were carried out using the same procedure as was used in Exercises 1-3, but with a wide scale of pai icula sizes (0.5 - 3 microns) and a broader scale of concentrations (ü.B - 3.2% by volume) as in example 2. The calcined aluminum oxide used in the experiments was obtained from Agsco Corporation, 621 Route 46, Hasbrouck, ND 07604, and it is in the form of platelets, referred to as Alumina # 1. The CPP values were measured using the procedure described at the end of Example 3. The CPP / GMC values were then calculated as described above. These data are presented in Table 4. It can be seen from the data in the tables that the CPP / GMC values are affected by all listed variables (ie, particle size, particle concentration, area density). , and the fiber dpf). In this way, preference comparisons are made for tests on fabrics having similar area densities.

However, it can be observed from the data in Table 4 that at a level of 2.4% by volume (6.0% by weight), with a particle size of 2 microns, the CPP / GMC values for fabrics made of textile fibers (2.8 dpf) and having area densities of less than about 339 grams / meter2 were greater than about 100. (Samples Nos. 22-24 and 30). This is much more than a 50% reduction on the average value of CPP / GMC of approximately 53 that was determined for the PET fiber without filler * of comparable fiber size and area density (the three Controls in the table). l). The average CPP / GMC values for all PET samples with tungsten filler in Table 3 (70) and all PET samples with aluminum oxide filler in Table 4 (75) are also significantly higher than the average the cont oles. It should be understood that the embodiments of the invention described above are illustrative only and that modification along these may occur for an expert in the art. Accordingly, this invention should not be considered as limited to the embodiments described herein. 1. 9 TABLE 1 Resistance to cuts of PET filled with a ^. n i Tenacity (gpd), fllargaiiento (X), Module (gpd), measured using test method B-3B22 of flSTU. 2 Cutting protection performance, measured using the CPP test from Ashland. 3rd 6th by square square.

TABLE 2 Resistance to cuts of PET filled with alumina Tenacity (gpd), Elongation (X), Module (gpd), measured using the D-3822 test method of flSTH. Cutting protection performance, measured using the CPP test from Ashland. Fat per square meter.

TABLE 3 Resistance to cuts of PET filled with tungsten CONC is the concentration of hard particles, measured as a. in volume in PET. DPF is the denier of fiber in dpf. Tenacity, elongation and nodule are the tensile properties of the fiber, measured by the test method D-3822 of fiSTil. SflC is the density of the area of the woven fabrics, led in gratos by square tetro. CPP is the CPP value measured by the CPP test of Ashland. CPP / GNC is the ratio of the CPP value to the density of the area (6flC). * led by the method described in Example 1. 0 0 TABLE 4 Resistance to cuts of PET filled with alumina 73 continuation of table 4 DPF is the fiber denier in dpf. Tenacity, Elongation and Module are the tensile properties of the fiber, measured by the test method D-3822 of ASTM. 6MC is the density of the area of woven fabrics, measured in grams per square meter. CPP is the CPP value measured by the CPP test of Ashland. CPP / GMC is the ratio of the CPP value to the area density (GMC). measured by the method described in Example 1. 1-GMC is high and CPP / GMC is bao because the glove is coated with plastic to improve the gripping performance.

Claims (15)

NOVELTY OF THE INVENTION CLAIMS

1. - A fiber i esiste to the cut that comprises a melt-processable isotropic polymer and a hard filler * uniformly distributed in said fiber, said fiber t Lene a hardness value of Mohs of rnas do 3; said filler * has an average particle size on the scale from 0.25 ml to 10 microns; said filler is present in an amount of about 0.1% to about% by volume, said fiber having a denier in the scale from about i to about darnen + e 50 dpf.

2. A fiber resistant to cutting according to claim 1, wherein said hard filler * has a hardness value of more than 5 rohs. 3.- A cutting resistant fiber according to claim 1, in that the average particle size of said hard filler is in the range of 1 to 6 microns. 4. A cut resistant fiber according to claim 1, wherein the average particle size of said hard filler is 3 microns. 5. A cutting resistant fiber according to claim 3, wherein said hard filler is a non-metal selected from the group consisting of metal oxides, including aluminum oxide and silicon dioxide, metal carbides, nitrides of metal, metal sulphides, metal silicates, metal licides, metal phalluses, metal phosphates, metal borides and mixtures of metals, except that said hard filler is not titanium dioxide. - A cut resistant fiber according to claim 5, wherein said hard filler is included in an amount of 0.5% to about 3% on a volume basis 7., - A fiber resistant to short conformity. with claim 5, wherein said hard filler * is included in an amount of 2.1% by volume 8. A cut resistant fiber according to claim 6, wherein said hard filler is calcined aluminum oxide. 9.- A fiber resi to the cut of c according to claim 3, wherein said hard filler is a metal or metal alloy. 10. A cut resistant fiber according to claim 9, wherein said hard filler is included in an amount of 0.5% to 3% by volume. 11. A cut resistant fiber according to claim 9, wherein said hard filler is included in an amount of 2.1% by volume. 12. A cut resistant fiber according to claim 10, wherein said hard filler is selected from the group consisting of iron, steel, nickel, 2 (5) tungsten and mixtures of the isms. 1

3. A core resistant fiber according to claim 1, wherein said melt-processable isotropic polymer is selected from the group consisting of polyalkyl phthalates or polychlorinated naphthalates, sulphides. of wood pulp, aliphatic and aliphatic-aromatic polyarnides, polyesters of clohexanodirnetanol and terephthalic acid and pollen inas. 1

4. A cut resistant fibril according to claim 1, wherein said melt processable isotropic polymer is selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate, Letlleno poly naphthalate, poly phenlene sulfide. , t reftal to polil, 4-c? clohexane Lrnetanol, nylon-6 and nylon-66, polyethylene and polypropylene. 1

5. A cutting resistant fiber according to any of claims 1, 6, B and 12, wherein said melt-processable isotropic polymer is polyethylene terephthalate. 1. A cutting resistant fiber according to claim 7, wherein said hard filler is calcined aluminum oxide and said melt-processable isotropic polymer is polyethylene terephthalate 17. A method for making a fiber or yarn having increased cut resistance, comprising the steps of: (a) making a uniform blend of 0.1% to 5% by volume of (1) a hard filler having a hardness value of Mohs of more than 3 and an average particle size on the scale from 0.25 microns to 10 microns, and (2) a melt-processable isotropic polymer selected from the group consisting of polyethylene terephthalate, full polybutylene terephthalate, polyalkylene naphthalate, poly phenol sulfide ,? ol? terephtalate, 4-cyclohexanedirithanol, nylon-6 and nylon-66, full polyethylene and polypropylene; and (b) spinning said uniform blend to form a fiber or yarn, wherein said fiber or fiber in said yarn has a denier * in the range of 1 to 50 dpf. IR.- A method for making * a fabric having increased cut resistance, comprising the steps of: (a) making a fiber or yarn according to the method of claim 17, and (b) making said fiber or yarn to form a fabric. 19. A cut resistant fiber comprising a polymer that is not processable by melting and a hard filler uniformly distributed in said fiber, said fiber having a hardness value of Mohs of more than 3; said filler has an average particle size in the range of 0.25 microns to 10 microns; said filler is present in an amount from about 0.1% to about 5% by volume. 20. The cutting resistant fiber according to claim 19, wherein said polymer that is not melt processable is a polyar- anide. 21. The cut resistant fiber according to claim 20, wherein said pol laranide is the polymer of p-phenylenediainine and terephthalic acid. 22. A cutting resistant film comprising a multiplicity of fibers according to claim 1, wherein said fibers have a denier in the range of 1.5 to 15 dpf.