JP6874468B2 - 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, knitted fabrics 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, dissatisfaction was seen from the viewpoint 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.

Therefore, 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 1 and 2).

Special Table 2010-5007026 Special Table 2015-518528

However, due to increasing safety awareness in recent years, there is a demand for materials with higher cut resistance than before.
Further, when the technique disclosed in Patent Documents 1 and 2 is used, 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 develop a novel polyethylene fiber having excellent cut resistance and high productivity, and to provide a product using the fiber.

As a result of diligent studies, the present inventors have found that the above problems can be solved by the means shown below, and have completed the present invention. That is, the present invention has the following configuration.

1. 1. A fiber made of polyethylene having an ultimate viscosity [η] of 4.9 dL / g or more and 40.0 dL / g or less, a hard particle having an aspect ratio of less than 3, and an average particle size of 3.0 μm or more and 15.0 μm or less. Polyethylene fiber characterized by containing.
2. The polyethylene fiber according to 1 above, which contains 5% by mass or more of the hard particles.
3. 3. The polyethylene fiber according to 1 or 2 above, wherein the hard particles are silica or alumina.
4. In the cut resistance evaluation according to the European standard ^{EN388, the level of cut resistance when the fabric is 350 g / m 2} ± 35 g / m ² is 4 or more. Any one of the above 1 to 3 polyethylene fibers. 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 polyethylene fibers having excellent cut resistance and high productivity, and products using the fibers.

Hereinafter, the present invention will be described in detail.
The polyethylene fiber of the present invention has an intrinsic viscosity of 4.9 dL / g or more, preferably 8.0 dL / g or more. Further, it is 40.0 dL / g or less, preferably 30.0 dL / g or less, and more preferably 25.0 dL / g or less.

If the ultimate viscosity is less than 4.9 dL / g, a high-strength multifilament may not be obtained. On the other hand, the upper limit of the ultimate viscosity does not matter as long as a high-strength multifilament can be obtained, but if the ultimate viscosity of polyethylene is too high, the workability is lowered and it becomes difficult to produce the multifilament. It is preferably in the above range.

The polyethylene fiber of the present invention contains a plurality of hard particles having an aspect ratio of less than 3. The aspect ratio of the hard particles contained in the polyethylene fiber of the present invention may be less than 3, but is preferably 1 or more and 2 or less. Here, the aspect ratio of the hard particles is defined as a width orthogonal to the maximum major axis / maximum major axis in the microscope image of the hard particles based on JIS8900-1. 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 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 main raw material for the hard particles contained in the polyethylene fiber of the present invention is not particularly limited, but silica, alumina or the like that does not easily aggregate in the polymer can be used. Of these, those made of silica are preferable.

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

The average particle size of the plurality of hard particles contained in the polyethylene fiber of the present invention is 3.0 μm or more, preferably 5.0 μm or more. When the average particle size of the hard particles is larger than 15.0 μm, the filtration filter is clogged during spinning, and the productivity of the fibers is significantly reduced, and in particular, the stretchability is significantly reduced.

The content of the plurality of hard particles contained in the polyethylene fiber of the present invention is 5% by mass or 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 frequency of contact 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 mixing with the solution used for spinning the polyethylene fiber of the present invention, it is desirable to add a dispersant in an amount of 0.1% by mass or more and less than 30% by mass with respect to the hard particles. As the dispersant, a nonionic or anionic surfactant is preferable. By adding the dispersant, the sedimentation rate of the hard particles is reduced and the dispersibility of the particles is improved. Further, when 30% by mass or more is added, yarn breakage occurs during spinning.

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 knitted fabric (woven or knitted fabric) becomes hard, 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 average strength of the polyethylene fiber of the present invention is preferably 10 cN / dtex or more, preferably 15 cN / dtex or more. If the average strength is less than 10 cN / dtex, the strength may be insufficient when the applied product is prepared.

As for the method for obtaining the polyethylene fiber of the present invention, for example, a gel spinning method can be used from the viewpoint of ensuring high strength. Although it can be produced by melt spinning, the range of application is limited when an applied product is produced because the strength is reduced by adding hard particles.

Therefore, it is preferable to use the melt spinning method for producing the polyethylene fiber of the present invention. The method for producing the polyethylene fiber of the present invention by using the gel 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.

In the production method of the present invention, the polyethylene concentration in the solution may be changed depending on the properties of the solvent, the molecular weight of polyethylene, and the molecular weight distribution. In particular, when polyethylene having a very high molecular weight, for example, a measurement temperature of 135 ° C. and a decalin as a solvent and a limit viscosity [η] of 14 dL / g or more is used, a mixed dope having a concentration of 50% by mass or more has a high viscosity. Therefore, brittle fracture is likely to occur during spinning, which makes spinning very difficult. On the other hand, the disadvantage of using a mixed dope with a concentration of less than 0.5% by mass, for example, is that the yield is reduced and the cost of solvent separation and recovery is increased.

The mixed dope used can be a variety of methods, such as suspending solid polyethylene in a solvent and subsequently stirring at high temperature, or mixing the suspension with a twin-screw extruder equipped with a transport section. It can be manufactured by using it. The mixed dope used may be a mixture of hard particles in addition to the solution and the polyethylene resin, and a dispersant may be further added.

In the production method of the present invention, the mixed dope is made into a dope filament through a spinneret formed by arranging a plurality of orifices. The temperature at the time of conversion to the dope filament must be selected above the dissolution point. This dissolution point depends, of course, on the selected solvent and concentration, and is preferably at least 140 ° C. or higher, preferably at least 150 ° C. or higher. Of course, this temperature is selected below the decomposition temperature of the polyethylene.

In the production method of the present invention, the dope filament is cooled using a pre-rectified gas or liquid. Examples of the gas used include air or an inert gas such as nitrogen or argon. Further, examples of the liquid used include water and the like.

In the production method of the present invention, it is preferable that the orifice portion is stretched 30 times or more and 400 times or less by passing through at least one stretching step with respect to the discharge rate of the orifice portion.

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 are 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 gloves and vests described above, they are suitably used as tapes, ropes, nets, fishing lines, material protective covers, sheets, kite threads, bowstrings, sail cloths, and curtain materials. 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 machine tool part, a battery separator, and a chemical filter. Of course, the polyethylene fiber of the present invention is not limited to being used as 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 be adapted to the gist of the above 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 Examples and Comparative Examples described later and the tubular knitting (knitted sample) using the fibers will be described.

(1) Extreme viscosity The specific viscosities of various dilute solutions are measured with a Ubbelohde-type capillary viscosity tube with decalin at 135 ° C., and the specific viscosity is divided by the concentration to obtain the minimum squared approximation of the plot. The ultimate viscosity was determined from the extrapolation point to the origin of the straight line. At the time of measurement, 1% by mass of an antioxidant (trade name "Yoshinox BHT" manufactured by Yoshitomi Pharmaceutical Co., Ltd.) was added to the polymer, and the sample was stirred and dissolved at 135 ° C. for 24 hours to prepare a measurement solution.

(2) 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 and 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 was completely ashed, it was allowed to cool in a desiccator to obtain ash. The aspect ratio was calculated by taking SEM photographs of the ash, measuring the lengths of the major and minor axes of 10 randomly selected hard particles, and calculating the average value. Since the hard particles have high hardness, it is considered that the shape does not change even when heated.

(3) 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 and burned until it became ash and a carbonaceous substance, and then placed in an electric furnace and heated at a temperature equal to or 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 its mass was measured to determine the ash content. The content of hard particles was determined from the obtained ash content and the fiber content.

(4) Cut resistance The cut resistance was measured using a coup tester (manufactured by SODMAT) based on the EN388 method, which is a European standard. Aluminum foil was provided on the sample table of this device, and the knitted sample was placed on it. Next, the circular blade provided in the device was run over 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. The counter attached to the device counts while the circular blade is operating, and the value is recorded.

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 type φ45 mm manufactured by OLFA Co., Ltd. The material was SKS-7 tungsten steel, and the blade thickness was 0.3 mm. In addition, the load applied during the test was set to 3.14 N (320 gf) for evaluation.

(Example 1)
1-decanol is a polymer obtained by mixing 88% by mass of polyethylene resin having an ultimate viscosity of 18.0 dL / g and 12% by mass of spherical silica (hard particles) having an aspect ratio of 1.4 and an average particle size of 3 μm. A dope was prepared by diluting with decalin containing 5% to 3%. The aspect ratio of the hard particles was an average of 10 particles as described above, and the range was 1.1 to 2.3. This dope was supplied to an extruder to be gelled at 190 ° C., and was discharged from a spinneret having an orifice diameter of φ0.8 mm and 48H at a nozzle surface temperature of 190 ° C. with a single-hole discharge rate of 2.0 g / min.

The discharged yarn was cooled with water, passed through a drying and heating step, and then wound into a cheese shape at a spinning speed of 50 m / min to obtain an undrawn yarn. Next, the fibers were heated with hot air at 145 ° C. and stretched at the maximum magnification capable of being stably stretched, and then wound up and combined yarn was carried out so as to have a total of 880 dtex ± 88 dtex to obtain the fibers of Example 1. In the following examples and comparative examples including this example, the drawn yarns are combined so as to have a desired dtex, but fiber splitting may also be performed.

Table 1 shows the physical characteristics of the obtained fibers and the content of hard particles. Further, using the obtained fibers, a tubular knitting ^{machine of Example 1 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. Table 1 shows the index values of the obtained tube knitting coup testers.

(Example 2)
Undrawn yarn was obtained in the same manner as in Example 1 except that 12% by mass of silica particles (hard particles) having an aspect ratio of 1.5 and an average particle size of 7 μm were used under the conditions of Example 1. A drawn yarn was obtained from the obtained undrawn yarn in the same manner as in Example 1. From the obtained drawn yarn, the fibers and the tubular knitting of Example 2 were obtained in the same manner as in Example 1. Table 1 shows the physical characteristics of the obtained fibers, the content of hard particles, and the index value of the tubular knitted fabric.

(Example 3)
Under the conditions of Example 1, 95% by mass of a polyethylene resin having an ultimate viscosity of 18.0 dL / g and 5% by mass of silica particles (hard particles) having an aspect ratio of 1.5 and an average particle diameter of 7 μm are used. An undrawn yarn was obtained in the same manner as in Example 1 except that the undrawn yarn was obtained. A drawn yarn was obtained from the obtained undrawn yarn in the same manner as in Example 1. From the obtained drawn yarn, the fibers and the tubular knitting of Example 3 were obtained in the same manner as in Example 1. Table 1 shows the physical characteristics of the obtained fibers, the content of hard particles, and the index value of the tubular knitted fabric.

(Example 4)
Undrawn yarn was obtained in the same manner as in Example 1 except that 12% by mass of silica particles (hard particles) having an aspect ratio of 1.5 and an average particle size of 15 μm were used under the conditions of Example 1. A drawn yarn was obtained from the obtained undrawn yarn in the same manner as in Example 1. From the obtained drawn yarn, the fibers and the tubular knitting of Example 4 were obtained in the same manner as in Example 1. Table 1 shows the physical characteristics of the obtained fibers, the content of hard particles, and the index value of the tubular knitted fabric.

(Example 5)
Undrawn yarn was obtained in the same manner as in Example 1 except that 12% by mass of alumina particles (hard particles) having an aspect ratio of 1.6 and an average particle size of 7 μm were used under the conditions of Example 1. A drawn yarn was obtained from the obtained undrawn yarn in the same manner as in Example 1. From the obtained drawn yarn, the fibers and the tubular knitting of Example 5 were obtained in the same manner as in Example 1. Table 1 shows the physical characteristics of the obtained fibers, the content of hard particles, and the index value of the tubular knitted fabric.

(Comparative Example 1)
Undrawn yarn was obtained in the same manner as in Example 1 except that 12% by mass of silica particles (hard particles) having an aspect ratio of 1.5 and an average particle size of 2 μm were used under the conditions of Example 1. A drawn yarn was obtained from the obtained undrawn yarn in the same manner as in Example 1. From the obtained drawn yarn, the fibers of Comparative Example 1 and the tubular knitting were obtained in the same manner as in Example 1. Table 1 shows the physical characteristics of the obtained fibers, the content of hard particles, and the index value of the tubular knitted fabric.

(Comparative Example 2)
A dope was prepared by mixing 65% by mass of a polyethylene resin having an ultimate viscosity of 18.0 dL / g and 35% by mass of silica particles (hard particles) having an aspect ratio of 1.5 and an average particle diameter of 7 μm. It was not mixed sufficiently and an undrawn yarn could not be obtained.

(Comparative Example 3)
Under the conditions of Example 1, a dope was prepared using 12% by mass of silica particles (hard particles) having an aspect ratio of 1.5 and an average particle size of 17 μm, but clogging occurred during spinning and the undrawn yarn was used. Could not be obtained.

(Comparative Example 4)
Under the conditions of Example 1, 97% by mass of a polyethylene resin having an ultimate viscosity of 18.0 dL / g and 3% by mass of silica particles (hard particles) having an aspect ratio of 1.5 and an average particle diameter of 7 μm were used. An undrawn yarn was obtained in the same manner as in Example 1 except that the undrawn yarn was obtained. A drawn yarn was obtained from the obtained undrawn yarn in the same manner as in Example 1. From the obtained drawn yarn, the fibers of Comparative Example 4 and the tubular knitting were obtained in the same manner as in Example 1. Table 1 shows the physical characteristics of the obtained fibers, the content of hard particles, and the index value of the tubular knitted fabric.

(Comparative Example 5)
Under the conditions of Example 1, a dope was prepared using 12% by mass of silica particles (hard particles) having an aspect ratio of 18 and an average particle size of 7 μm, but clogging occurred during spinning to obtain an undrawn yarn. I couldn't.

(Comparative Example 6)
Under the conditions of Example 1, 88% by mass of a polyethylene resin having an ultimate viscosity of 1.5 dL / g and 12% by mass of silica particles (hard particles) having an aspect ratio of 1.5 and an average particle diameter of 7 μm are used. An undrawn yarn was obtained in the same manner as in Example 1 except that the undrawn yarn was obtained. A drawn yarn was obtained from the obtained undrawn yarn in the same manner as in Example 1. From the obtained drawn yarn, the fibers of Comparative Example 6 and the tubular knitting were obtained in the same manner as in Example 1. Table 1 shows the physical characteristics of the obtained fibers, the content of hard particles, and the index value of the tubular knitted fabric.

このように、上記実施例１〜５および比較例１〜６から、平均粒径サイズが３．０μm以上１５.０μm以下複数の硬質粒子を含有するポリエチレン繊維は、耐切創性に優れた繊維であることがわかる。

As described above, from Examples 1 to 5 and Comparative Examples 1 to 6, the polyethylene fiber containing a plurality of hard particles having an average particle size of 3.0 μm or more and 15.0 μm or less is a fiber having excellent cut resistance. It turns out that there is.

Although the embodiments and the respective examples of the present invention have been described above, the embodiments and the respective 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 resistance woven and knitted fabrics, gloves, vests and the like utilizing the cut resistance. In addition, as the 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 thread, artificial tendon, artificial muscle, It can be used for industrial materials such as fiber reinforced resin reinforcing materials, cement reinforcing materials, fiber reinforced rubber reinforcing materials, machine tool parts, battery separators, and chemical filters. 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 (2)

Fiber made of polyethylene having an ultimate viscosity [η] of 4.9 dL / g or more and 40.0 dL / g or less, silica having an aspect ratio of less than 3, and an average particle size of 3.0 μm or more and 15.0 μm or less. A polyethylene fiber containing 5% by mass or more of hard particles which are alumina. A product comprising the polyethylene fiber according to claim 1.