JP7070667B2 - Polyethylene fiber and products using it - Google Patents

Description

The present invention relates to polyethylene fibers having excellent cut resistance and products containing the fibers.

Conventionally, natural fibers such as cotton and general organic fibers have been used as cut-resistant materials. In addition, gloves made by knitting these fibers have been widely used in fields where cut resistance is required. Therefore, knits and woven fabrics made of spun yarns of high-strength fibers such as aramid fibers have been devised to impart a cut resistance function. However, these were dissatisfied in terms of hair loss and durability. On the other hand, as another means, attempts have been made to improve cut resistance by using metal fibers in combination with organic fibers and natural fibers. However, there is a problem that the texture becomes hard and the flexibility is impaired by combining the metal fibers.

In order to solve the above problems, a technique of polyethylene fiber having excellent cut resistance, which defines a weight average molecular weight (Mw) and a ratio (Mw / Mn) of a weight average molecular weight to a number average molecular weight (Mn), is known. (See, for example, Patent Document 1).

Further, a technique of ultra-high molecular weight polyethylene fiber having excellent cut resistance due to a thread containing a hard fiber is known (see, for example, Patent Documents 2 and 3).

Further, a polyethylene fiber containing hard particles such as alumina and having excellent cut resistance has also been proposed (see Patent Document 4).

Japanese Unexamined Patent Publication No. 2004-019050 Special Table 2010-5007026 Japanese Patent Publication No. 2015-518528 Japanese Unexamined Patent Publication No. 2017-179684

However, when the technique disclosed in Patent Documents 2 and 3 is used for melt spinning, there is a problem that the added hard fiber clogs the filtration filter in the spinning process and significantly reduces the productivity.

Therefore, the present invention has been made to solve the problems of the prior art. That is, an object of the present invention is to provide a novel polyethylene fiber having excellent cut resistance and high productivity, and a product using the fiber.

The present inventors have conducted diligent studies in order to solve the above problems. As a result, for the polyethylene fiber containing predetermined hard particles, the density ratio V represented by V1 / V2 (in the formula, V1 is the density of the polyethylene fiber measured by the density gradient tube method, and V2 is the pycnometer method). The present invention was completed by finding that the intended purpose can be achieved by controlling the density of the polyethylene fiber measured in 1) within a predetermined range.
That is, the present invention has the following configuration.

1. 1. Hard particles having an aspect ratio of less than 3 and an average minor axis of 20 μm or less, the hard particles containing an element having an atomic number of 14 or more.
A polyethylene fiber having a density ratio V represented by the following formula, which satisfies 0.70 or more and less than 0.97.
V = V1 / V2
During the ceremony
V1 is the density of polyethylene fibers measured by the density gradient tube method.
V2 is the density of polyethylene fibers measured by the pycnometer method.
2. 2. The polyethylene fiber according to 1 above, wherein the ultimate viscosity [η] of polyethylene is 0.8 dL / g or more and less than 4.9 dL / g.
3. 3. The polyethylene fiber according to 1 or 2 above, wherein the hard particles are a metal, a silicon compound, or a mineral.
4. The polyethylene fiber according to any one of 1 to 3 above, wherein the polyethylene fiber contains 5% by mass or more of the hard particles.
5. A product comprising the polyethylene fiber according to any one of 1 to 4 above.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a polyethylene fiber having excellent cut resistance and high productivity, and a product using the fiber.

Hereinafter, the present invention will be described in detail.
The polyethylene fiber of the present invention preferably has an intrinsic viscosity [η] of 0.8 dL / g or more and less than 4.9 dL / g, more preferably 1.0 dL / g or more and 4.0 dL / g or less. More preferably, it is 1.2 dL / g or more and 2.5 dL / g or less.

By setting the ultimate viscosity to less than 4.9 dL / g, spinning by the melt spinning method becomes easy, and it is not necessary to spin by so-called gel spinning or the like. Therefore, it is advantageous in terms of controlling manufacturing costs and simplifying work processes. Furthermore, since no solvent is used during manufacturing, the impact on workers and the environment is small. In addition, since there is no residual solvent in the fibers of the product, there is no adverse effect of the solvent on the product user. Further, by setting the ultimate viscosity to 0.8 dL / g or more, the number of structural defects in the fiber can be reduced by reducing the molecular terminal groups of polyethylene. Therefore, it is possible to improve the mechanical characteristics of the fiber such as strength and elastic modulus and the cut resistance performance.

The preferable weight average molecular weight (Mw) of the polyethylene fiber according to the present invention is 50,000 to 600,000. By setting Mw to 50,000 or more, the number of structural defects in the fiber can be reduced by reducing the molecular terminal groups of polyethylene. Therefore, the mechanical properties of the fiber such as strength and elastic modulus and the cut resistance are improved. On the other hand, when Mw is set to 600,000 or less, spinning by the melt spinning method becomes easy, and it is not necessary to spin by so-called gel spinning or the like. Therefore, it is advantageous in terms of controlling manufacturing costs and simplifying work processes. Furthermore, since no solvent is used during manufacturing, the impact on workers and the environment is small. In addition, since there is no residual solvent in the fibers of the product, there is no adverse effect of the solvent on the product user.

Further, the polyethylene in the present invention may be used as long as the repeating unit thereof is substantially ethylene, and the ethylene and a small amount of other monomers; for example, α-olefin, acrylic acid and its derivative, methacrylic acid and its derivative, vinylsilane and its derivative. It may be a copolymer with a derivative or the like. Alternatively, it may be a blend of these copolymers, a copolymer of an ethylene homopolymer and the above copolymer, or a blend of an ethylene homopolymer and another homopolymer such as α-olefin. In particular, the inclusion of short-chain or long-chain branches to some extent using a copolymer with an α-olefin such as propylene or butene-1 is a method for producing the polyethylene fiber of the present invention, especially in spinning and drawing. It is more preferable because it imparts the above stability. However, if the content other than ethylene increases too much, it will adversely affect stretching. Therefore, from the viewpoint of obtaining polyethylene fibers with high strength and high elastic modulus, the ratio of components other than ethylene to the total polyethylene fibers is monomer. The unit is preferably 0.2 mol% or less, more preferably 0.1 mol% or less. Of course, the polyethylene in the present invention may be composed of ethylene alone.

The polyethylene fiber of the present invention is characterized in that the ratio V of the density represented by the following formula ratio (hereinafter, may be simply referred to as V) satisfies 0.70 or more and less than 0.97. As a result, polyethylene fibers having excellent cut resistance can be obtained.
V = V1 / V2

Here, V1 is the density of the polyethylene fiber measured by the density gradient tube method. According to the density gradient tube method, the density including not only the polyethylene fiber itself but also the voids inside the polyethylene fiber is calculated. On the other hand, V2 is the density of polyethylene fibers measured by the pycnometer method. According to the pycnometer method, the density including voids inside the polyethylene fiber is not calculated, but the density (true density) of the polyethylene fiber itself is calculated.

That is, V represented by the ratio of V1 / V2 can be an index close to the porosity of the polyethylene fiber (not necessarily the same from a scientific point of view). The larger the V, the smaller the voids and the more likely it is that they are tightly clogged, and the impact that is absorbed is softened, so that the incision resistance is improved. Therefore, in the present invention, the above V is set to 0.70 or more. However, if V becomes too large (that is, the fibers are not pulled), the crystallinity decreases and the cut resistance decreases, so the upper limit is set to less than 0.97.

Both V1 and V2 are measured by a method according to JIS K-0061-2001 and JIS K-7112-1991. These measurement methods will be described in detail in the section of Examples.

The polyethylene fiber of the present invention contains a plurality of hard particles. The hard particles in the present invention contain at least an element having an aspect ratio of less than 3, an average minor axis of 20 μm or less, and an atomic number of 14 or more.

The aspect ratio of the hard particles contained in the polyethylene fiber of the present invention may be less than 3, but preferably 1 or more and 2 or less. Here, the aspect ratio of the hard particle represents the shape of the particle defined by the value calculated based on JIS89001 (that is, the width orthogonal to the maximum diameter / maximum diameter in the microscope image of the particle). Index). The method for measuring the aspect ratio of hard particles will be described in detail in the column of Examples described later. If the aspect ratio of the hard particles is 3 or more, the filtration filter may be clogged during spinning, which may significantly reduce the productivity of the fibers, which is not preferable.

The average minor axis of the plurality of hard particles contained in the polyethylene fiber of the present invention is 20 μm or less. When the average minor axis of the hard particles is larger than 20 μm, the filtration filter is clogged during spinning, and the productivity of the fiber is significantly reduced, and in particular, the stretchability is significantly reduced. It is preferably 10 μm or less, more preferably 8 μm or less, still more preferably 5 μm or less. The lower limit of the average minor axis of the hard particles is not particularly limited, but it is preferably about 0.05 μm or more.
The average minor axis of the hard particles was calculated by measuring the minor axis (maximum minor axis) of each of the 10 hard particles by the same method as the aspect ratio of the hard particles described later, and obtaining the average value thereof.

The hard particles used in the present invention contain at least an element having an atomic number of 14 or more. Therefore, in the present invention, Al having an atomic number of 13 is not used as hard particles. Examples of the element having an atomic number of 14 or more include Si, Fe, Cu, Ti, Ni, Ag, Au, Pt, Co, Zn and the like. It is preferably Si, Fe and Ti.

Specific examples of the hard particles used in the present invention include metals, silicon compounds, and minerals.
Here, the metal means a metal having a Morse hardness of 3 or more, and examples thereof include tungsten, iron, titanium, chromium, zinc, manganese, nickel, copper, silver, and gold; and further, compounds of the metal. ..
The silicon compound is not particularly limited as long as it is a compound containing silicon, and examples thereof include silica, glass, and silicon carbide.
Examples of the mineral include quartz, rock wool, iron oxide and the like.

The shape of the plurality of hard particles contained in the polyethylene fiber of the present invention is preferably spherical or oblate. If the hard particles are fibrous, the filtration filter may be clogged during spinning, which may significantly reduce the productivity of the fibers, which is not preferable.

The plurality of hard particles contained in the polyethylene fiber of the present invention may be used as they are or may have a modified surface. As the surface modification, a dimethyl group, an epoxy group, a hexyl group, a phenyl group, a methacrylic group, a vinyl group, an isocyanate group and the like can be applied.

The content of the plurality of hard particles contained in the entire polyethylene fiber of the present invention is preferably 5% by mass or more, more preferably 10% by mass or more and 30% by mass or less. When the content of the hard particles is less than 5% by mass, the contact frequency between the hard particles existing in the fiber and the blade is low, and it is difficult to obtain the effect of improving the cut resistance.

When spinning the polyethylene fiber of the present invention, the hard particles may be used as a masterbatch kneaded with polyethylene in advance, or may be used alone.

The polyethylene fiber of the present invention preferably has a fiber diameter per single yarn of 45 μm or less, more preferably 37 μm or less. When the fiber diameter per single yarn is larger than 45 μm, the texture when formed into a woven fabric or a knitted fabric (woven or knitted fabric) becomes firm, and the flexibility is impaired. The fiber diameter per single yarn can be obtained, for example, by using a method of obtaining dtex and the specific gravity of the fiber, or a method of obtaining using a microscope. The upper limit is not particularly limited from the above viewpoint, but is preferably about 10 μm or more in consideration of productivity and the like.

The average strength of the polyethylene fiber of the present invention is preferably 4 cN / dtex or more, preferably 6 cN / dtex or more. If the average strength is less than 4 cN / dtex, the strength may be insufficient when the applied product is manufactured. The upper limit is not particularly limited from the above viewpoint, but is preferably about 50 cN / dtex or less in consideration of productivity such as spinnability.

The polyethylene fiber of the present invention may have a core-sheath structure applied thereto, or may have an irregular shape such as a star shape, a triangle shape, or a hollow shape.

As a production method for obtaining the polyethylene fiber of the present invention, for example, a melt spinning method can be used. Here, for example, when the gel spinning method, which is one of the methods for producing ultra-high molecular weight polyethylene fibers using a solvent, is used, high-strength polyethylene fibers can be obtained, but the productivity is not only low, but also due to the use of a solvent. It has a great impact on the health and environment of manufacturing workers, and the solvent remaining in the fiber has a great impact on the health of product users.

Therefore, it is preferable to use the melt spinning method for the polyethylene fiber of the present invention. The method for producing the polyethylene fiber of the present invention by using the melt spinning method will be specifically described below. The method for producing the polyethylene fiber of the present invention is not limited to the following steps and numerical values.

The above-mentioned polyethylene resin and hard particles in a powder state are blended and melt-extruded using an extruder or the like at a temperature higher than the melting point of the polyethylene resin, for example, 10 ° C. or higher, preferably 50 ° C. or higher, and more preferably 80 ° C. or higher. Then, using a fixed quantity supply device, the polyethylene resin is supplied to the spinning nozzle (spinning cap) at a temperature higher than the melting point of the polyethylene resin, for example, 80 ° C., preferably 100 ° C. or higher. At this time, the pressure of the inert gas supplied into the extruder is preferably 0.001 MPa or more and 0.8 MPa or less, more preferably 0.05 MPa or more, 0.7 MPa or less, still more preferably 0.1 MPa or more. , 0.5 MPa or less is recommended. Then, for example, a spinning nozzle having a diameter of 0.3 mm or more and 2.5 mm or less, preferably a diameter of 0.5 mm or more and 1.5 mm or less is discharged at a discharge amount of 0.1 g / min or more. The discharge line speed at the time of discharging the molten resin from the spinning nozzle is preferably 10 cm / min or more and 120 cm / min or less. More preferable discharge line velocities are 20 cm / min or more and 110 cm / min or less, and more preferably 30 cm / min or more and 100 cm / min or less.

Next, the discharged yarn is cooled to 5 to 40 ° C., then wound at 50 m / min or more, and the obtained undrawn yarn is further rolled at least once at a temperature equal to or lower than the melting point of the undrawn yarn. Stretch. Specifically, it is preferable to perform the stretching step in two or more steps. The initial temperature of drawing is preferably less than the crystal dispersion temperature of the undrawn yarn, more preferably 80 ° C. or lower, still more preferably 75 ° C. or lower. Next, it is preferable to draw the undrawn yarn at a crystal dispersion temperature or higher, a melting point or lower, preferably 90 ° C. or higher, and a melting point or lower.

Here, the crystal dispersion temperature is a temperature measured by the following method.
First, the solid viscoelasticity is measured using a solid viscoelasticity measuring device (“DMA Q800” manufactured by TA Instruments). "TA Universal Analysis" (manufactured by TA Instruments) is used for the analysis of the measured solid viscoelastic modulus. Here, the measurement start temperature is −140 ° C., the measurement end temperature is 140 ° C., and the temperature rise rate is 1.0 ° C./min. Further, the strain amount is 0.04%, and the initial load at the start of measurement is 0.05 cN / dtex. The measurement frequency is 11 Hz. Next, the loss elastic modulus is calculated based on the obtained solid viscoelastic modulus, the temperature dispersion is obtained from the low temperature side, the value of the loss elastic modulus is plotted on the vertical axis and the temperature is plotted on the horizontal axis. The peak value of the loss elastic modulus that appears on the highest temperature side is defined as the crystal dispersion temperature.

The draw ratio is preferably 6 times or more in total, more preferably 8 times or more, and further preferably 10 times or more. The total draw ratio is preferably 30 times or less, more preferably 25 times or less, and further preferably 20 times or less. When multi-step stretching is adopted, for example, when two-step stretching is performed, the stretching ratio of the first step is preferably 1.05 times or more and 4.00 times or less, and the second step stretching is preferably performed. The magnification is preferably 2.5 times or more and 15 times or less.

Products using the polyethylene fibers of the present invention, for example, woven and knitted fabrics, are suitably used as cut resistant woven and knitted fabrics, gloves, vests and the like. For example, gloves can be obtained by hanging the polyethylene fibers of the present invention on a knitting machine. Alternatively, the polyethylene fiber of the present invention can be woven on a loom to obtain a cloth, which can be cut and sewn to make gloves.

The gloves thus obtained can be used as, for example, gloves as they are, but if necessary, a resin can be applied to impart anti-slip properties. Examples of the resin used here include urethane-based and ethylene-based resins, but the resin is not particularly limited.

As can be seen from the examples described later, the polyethylene fiber of the present invention has excellent cut resistance.
Therefore, in addition to the above-mentioned woven and knitted fabrics such as gloves and vests, the products using the polyethylene fiber of the present invention include tapes, ropes, nets, fishing threads, material protective covers, sheets, kite threads, western bow strings, sail cloths, etc. It is suitably used as a curtain material. Of course, the products using the polyethylene fibers of the present invention are not limited to these.

Further, since the polyethylene fiber of the present invention has high cut resistance, a material utilizing the cut resistance, for example, a fiber reinforced resin reinforcing material, a cement reinforcing material, a fiber reinforced rubber reinforcing material, or an environmental change is expected. It is suitably used as a protective material, a bulletproof material, a medical suture, an artificial tendon, an artificial muscle, a fiber reinforced resin reinforcing material, a cement reinforcing material, a fiber reinforced rubber reinforcing material, a machine tool part, a battery separator, and a chemical filter. Of course, the polyethylene fiber of the present invention is not limited to these materials and can be used as various materials.

Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to the following examples, and it is of course possible to carry out the present invention with appropriate modifications within a range that can meet the purposes of the preceding and the following, and all of them are the techniques of the present invention. It is included in the target range.

First, the measurement and evaluation of the characteristic values performed on the fibers (fiber samples) produced in the examples and comparative examples described later and the tubular knitting (knitted sample) using the fibers will be described.

(1) Extreme viscosity [η]
The ultimate viscosity was measured using a Ubbelohde-type capillary viscosity tube using decalin heated to 135 ° C. as a solvent. Specifically, the specific viscosities of various dilute solutions were measured, and the ultimate viscosity was determined from the extrapolation point to the origin of the straight line obtained by the minimum square approximation of the plot with respect to the concentration of the viscosity. When measuring the specific viscosity, the fiber sample was divided or cut into pieces of about 5 mm length, 1% by mass of an antioxidant (Yoshinox BHT®, manufactured by Yoshitomi Pharmaceutical Co., Ltd.) was added to the polymer, and the temperature was 135 ° C. for 4 hours. The measurement solution was prepared by stirring and dissolving.

(2) V (= V1 / V2, density ratio)
V1 is the density of polyethylene fibers measured by the density gradient tube method, and V2 is the density of polyethylene fibers measured by the pycnometer method. Both V1 and V2 were measured by a method according to JIS K-0061-2001 and JIS K-7112-1991.
The specific measurement method is as follows.

First, V1 was measured as follows using a mixed solution of isopropanol and pure water as a solvent.
(Making a density gradient tube)
Using water as the heavy liquid and isopropyl alcohol as the light liquid, pour the light liquid into the glass tube with memory while continuously mixing the light liquid little by little. A density gradient tube was prepared so that the ratio of the light liquid increased toward the upper part of the tube. This density gradient tube was placed in a constant temperature bath at 30 ° C. ± 0.1 ° C.
Next, 10 glass balls having known specific densities (all having different specific densities) were gently put into the density gradient tube prepared as described above, and allowed to stand as it was for 1 day. After that, the distance between each glass ball and the liquid level is measured, and a calibration curve graph is created with the distance obtained at this time as the vertical axis and the specific gravity value of the glass sphere as the horizontal axis, and the graph is a straight line. It was confirmed that an accurate specific gravity liquid was obtained.
(Measurement of specific gravity)
A fiber sample (sample length: 6 to 8 mm) was charged into the density gradient tube prepared as described above, and the position of the fiber sample from the liquid surface was measured immediately after charging and 5 hours after charging. Using the above calibration curve prepared at the time of preparing the density gradient tube, the specific gravity value at the position of the sample was obtained.

On the other hand, V2 was measured using a helium as a solvent and a pycnometer of Shimadzu K-7112-1980 AccuPYC II 1340. Specifically, 5 g of the above fiber sample (sample length: 6 to 8 mm) was precisely weighed, helium gas was poured into the pycnometer, the volume was obtained, and the specific gravity was calculated.

(3) Aspect ratio of hard particles The aspect ratio of hard particles was determined by using an SEM photograph. The fiber sample was placed in a crucible, burned until it became ash and a carbonaceous substance, then placed in an electric furnace and heated above the decomposition temperature of polyethylene. When the carbonaceous material became completely ash, it was allowed to cool in a desiccator to obtain ash. An SEM photograph of the ash is taken, and for each of the 10 randomly selected hard particles, the major axis (maximum major axis) and the width orthogonal to the maximum major axis are measured, and the maximum major axis is divided by the width orthogonal to the maximum major axis. Then, the aspect ratio was calculated by obtaining the average value. Since the hard particles have high hardness, it is considered that the shape does not change even when heated.

(4) Average minor axis of hard particles For the average minor axis of hard particles, SEM photographs were taken in the same manner as in the above aspect ratio, and the minor axis (maximum minor axis) was measured for 10 randomly selected hard particles. , Calculated by calculating the average value.

(5) Content of hard particles The content of hard particles was determined by using ash content measurement based on JIS-2272. 1.0 g of the fiber sample was placed in a crucible, burned until it became ash and a carbonaceous substance, then placed in an electric furnace and heated at a temperature higher than the decomposition temperature of polyethylene. After the carbonaceous substance was completely turned into ash, it was allowed to cool in a desiccator and the mass was measured to determine the ash content. The content of hard particles was determined based on the mass ratio of the ash content to the total of the obtained ash content and the fiber content.

(6) Cut resistance The cut resistance was measured based on the EN388 method, which is a European standard, using a device of a coup tester (manufactured by SODMAT). Specifically, using each polyethylene fiber produced by the method described later, a tubular knitting machine having a basis weight of 350 g / m ² ± 35 g / m ² was produced using a circular knitting machine manufactured by Shima Seiki Seisakusho Co., Ltd. The index value of the obtained tube knitting coup tester was calculated as follows to evaluate the cut resistance.

Here, an aluminum foil is provided on the sample table of the above device, and the knitted sample is placed on the aluminum foil. Then, the circular blade provided in the device was run on the sample while rotating in the direction opposite to the running direction. When the knitted sample was cut, it was detected that the cut resistance test was completed by the contact between the circular blade and the aluminum foil and energization. While the circular blade was operating, the counter attached to the device counted and recorded the value.

In this test, a plain weave cotton cloth with a basis weight of about 200 g / m ² was used as a blank, and the cut level of the knitted sample was evaluated. The test was started from the blank, the blank test and the knitted sample test were alternated, the knitted sample was tested 5 times, and finally the 6th blank was tested to complete one set of tests. Five sets of the above tests were performed, and the average Index value (index value) of the five sets was used as a substitute evaluation for cut resistance. The higher the index value, the better the cut resistance.

The index value is calculated by the following formula.
A = (count value of cotton cloth before sample test + count value of cotton cloth after sample test) / 2
Index value = (sample count value + A) / A

The cutter used for the evaluation of cut resistance is a rotary cutter L-shaped φ45 mm manufactured by OLFA Co., Ltd. The material was SKS-7 tungsten steel, and the blade thickness was 0.3 mm. Moreover, the load applied at the time of the test was set to 3.14N (320gf) and the evaluation was performed.

In this example, the index value obtained in Example 1 is set as the cut resistance 100, and this is used as a reference value, and the other Examples 2 to 4 and Comparative Examples 1 to 5 are relative ratios to the Example 1. Represented cut resistance. For example, the cut resistance of Comparative Example 1 is 52, which means that when the cut resistance of Example 1 is 100%, only 52% (about half) is obtained.

(Example 1)
A blend polymer is prepared by mixing 78% by mass of polyethylene pellets having an ultimate viscosity of 1.9 dL / g and 22% by mass of silica particles (hard particles) having an aspect ratio of 1.1 and an average minor axis of 2.0 μm. bottom. The aspect ratio of the hard particles was an average of 10 particles as described above, and the range was 0.9 to 1.2. This blended polymer was supplied to an extruder, melted at 280 ° C., and discharged from a spinneret having an orifice diameter of φ0.8 mm and 30H at a nozzle surface temperature of 288 ° C. and a single hole discharge rate of 0.32 g / min.

The discharged yarn was passed through a heat insulating section of 10 cm, cooled at 18 ° C. at 0.5 m / sec, and then wound into a cheese shape at a spinning speed of 200 m / min to obtain an undrawn yarn. Then, it was heated with hot air at 100 ° C. and wound at the maximum drawing ratio capable of stably drawing to obtain a drawn yarn. The drawn yarns were combined so as to have a total of 880 dtex ± 88 dtex to obtain the polyethylene fiber of Example 1. Using the obtained polyethylene fiber, a tubular knitted fabric was produced by the above method and the cut resistance was evaluated. These results are shown in Table 1. In the following examples and comparative examples including this example, those stretched 3 times at room temperature and 2.3 times at 100 ° C. were used.

The V of the polyethylene fiber of Example 1 thus obtained was calculated by the above method, and the cut resistance was evaluated. These results are shown in Table 1.

(Examples 2 to 6, Comparative Example 1, Comparative Example 5)
Under the conditions of Example 1, the same as that of Example 1 except that the ultimate viscosity of the polymer; the material of the hard particles, the average minor axis, the aspect ratio, and the content; the V of the polyethylene fiber was changed as shown in Table 1. A drawn yarn was obtained and the cut resistance was evaluated. These results are shown in Table 1.

(Comparative Example 2)
Under the conditions of Example 1, 94% by mass of polyethylene pellets having an ultimate viscosity of 5.5 dL / g and 6% by mass of silica particles (hard particles) having an aspect ratio of 1.1 and an average minor axis of 2.0 μm. Was mixed to prepare a blended polymer, but the polymer and the hard particles did not mix and an undrawn yarn could not be obtained.

(Comparative Example 3)
Under the conditions of Example 1, a blend polymer was prepared using 6% by mass of silica particles (hard particles) having an aspect ratio of 1.1 and an average minor axis of 25.0 μm, but clogging occurred during spinning. Undrawn yarn could not be obtained.

(Comparative Example 4)
Under the conditions of Example 1, a blended polymer was produced using 6% by mass of glass particles (hard particles) having an aspect ratio of 18.0 and an average minor axis of 7.0 μm, but clogging occurred during spinning. Undrawn yarn could not be obtained.

As can be seen from Table 1, Examples 1 to 6 using polyethylene fibers satisfying the requirements of the present invention are excellent in cut resistance. On the other hand, in Comparative Examples 1 and 5 in which V (V1 / V2) was outside the scope of the present invention, the cut resistance was lowered. Further, in Comparative Examples 2 to 4 in which any of the ultimate viscosity, the average minor diameter, and the aspect ratio did not satisfy the requirements of the present invention, the desired undrawn yarn could not be obtained.

Although the embodiments and the embodiments of the present invention have been described above, the embodiments and the embodiments disclosed this time are examples in all respects and are not limiting. The scope of the present invention is indicated by the scope of claims and includes all modifications within the meaning and scope equivalent to the scope of claims.

Since the polyethylene fiber of the present invention has high cut resistance, it can be used for cut resistant woven and knitted fabrics utilizing the cut resistance, such as gloves and vests. In addition, as the polyethylene fiber alone, tape, rope, net, fishing thread, material protective cover, sheet, kite thread, western bow string, sail cloth, curtain material, protective material, bulletproof material, medical suture, artificial tendon, artificial muscle , Fiber reinforced resin reinforcing material, cement reinforcing material, fiber reinforced rubber reinforcing material, machine tool parts, battery separators, chemical filters and other industrial materials. As described above, the polyethylene fiber of the present invention can exhibit excellent performance and can be widely applied, so that it can greatly contribute to the industrial world.

Claims (4)

True spherical and / or oblate hard particles having an aspect ratio of less than 3 and an average minor axis of 2.0 μm or more and 20 μm or less, wherein the hard particles contain an element having an atomic number of 14 or more.
In addition to containing 3% by mass or more of the hard particles in the polyethylene fiber,
The fiber diameter per single yarn of the polyethylene fiber is 45 μm or less, and the fiber diameter is 45 μm or less.
A polyethylene fiber having a density ratio V represented by the following formula, which satisfies 0.70 or more and less than 0.97.
V = V1 / V2
During the ceremony
V1 is the density of polyethylene fibers measured by the density gradient tube method.
V2 is the density of polyethylene fibers measured by the pycnometer method. The polyethylene fiber according to claim 1, wherein the ultimate viscosity [η] of polyethylene is 0.8 dL / g or more and less than 4.9 dL / g. The polyethylene fiber according to claim 1 or 2, wherein the hard particles are a metal, a silicon compound, or a mineral. A product comprising the polyethylene fiber according to any one of claims 1 to 3.