JPWO2020065842A1 - Polyethylene fiber and products using it - Google Patents

Abstract

Provided are a novel polyethylene fiber capable of stably exhibiting high cut resistance, suppressing agglutination of hard particles, and having high productivity, and a product using the fiber. The polyethylene fiber of the present invention contains hard particles having an aspect ratio of less than 3, a Hausner surface index of 1.06 or more represented by the following formula, and a specific surface area of 5.0 m2 / g or less. In Hausner's surface index = P2 / 4πA equation, P is the circumference of the particle projection image (μm), and A is the area of the particle projection image (μm2).

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, 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 polyethylene fiber technique having excellent cut resistance, which defines the weight average molecular weight (Mw) and the ratio (Mw / Mn) of the weight average molecular weight to the 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 having a polygonal shape and an average particle diameter of 1.0 μm or less and containing hard particles such as alumina and having excellent cut resistance has also been proposed (see Patent Document 4).

Japanese Unexamined Patent Publication No. 2004-109050 Special Table 2010-5007026 Special Table 2015-518528 Japanese Unexamined Patent Publication No. 2017-179684

However, when the techniques disclosed in Patent Documents 2 and 3 are used for melt spinning, there is a problem that the added hard fibers clog the filtration filter in the spinning process and significantly reduce the productivity.

Further, according to a detailed study by the present inventors, the polyethylene fiber of Patent Document 4 has a problem that the cut resistance evaluation varies widely and it is difficult to obtain a stable and high evaluation (poor reproducibility). However, it turned out newly.

The present invention has been made to solve the above problems, and an object of the present invention is that it can stably exhibit high cut resistance, agglomeration of hard particles is suppressed, and productivity is high. It is an object of the present invention to provide a high novel polyethylene fiber and a product using the fiber.

The present inventors have conducted diligent studies in order to solve the above problems. As a result, if the shape (multi-angle) and specific surface area of the hard particles contained in the polyethylene fiber are appropriately controlled, a polyethylene fiber having both stable and high cut resistance and hard particle aggregation resistance can be obtained. We found that and completed the present invention.

That is, the present invention has the following configuration.
1. 1. A polyethylene fiber containing hard particles having an aspect ratio of less than 3, a Hausner surface index represented by the following formula of 1.06 or more, and a specific surface area of 5.0 m ^{2 / g or less.}
Hauser surface index = P ² / 4πA
During the ceremony
P is the perimeter (μm) of the particle projection image,
A is the area of the particle projection image (μm ² ).
2. The polyethylene fiber according to 1 above, wherein the hard particles are silicon compounds.
3. 3. The polyethylene fiber according to 1 or 2 above, wherein the hard particles _{contain 20% by mass or more of SiO 2 in the hard particles.}
4. The polyethylene fiber according to any one of 1 to 3 above, wherein the average minor axis of the hard particles is 1.0 μm or more.
5. The polyethylene fiber according to any one of 1 to 4 above, wherein the hard particles have a Mohs hardness of 4.5 or more.
6. The polyethylene fiber according to any one of 1 to 5 above, wherein the ultimate viscosity [η] of polyethylene is 0.8 dL / g or more and less than 4.9 dL / g.
7. The polyethylene fiber according to any one of 1 to 6 above, wherein the polyethylene fiber contains 2% by mass or more of the hard particles.
8. A product comprising the polyethylene fiber according to any one of 1 to 7 above.
9. The product according to 8 above, wherein the product is a cut-resistant knitted fabric.
10. The product according to 8 or 9 above, wherein the product is a glove.

According to the present invention, a novel polyethylene fiber capable of stably exhibiting high cut resistance, suppressing agglutination of hard particles, and having high productivity, and a product using the fiber are provided. can do.

First, the background to the present invention will be described.
Even after proposing the polyethylene fiber of Patent Document 4, the present inventors have continued to study in order to further improve the cut resistance. Specifically, the hard particles described in Patent Document 4; specifically, polyethylene containing hard particles having a polygonal shape, an average particle diameter of 1.0 μm or less, and a Mohs hardness of 4.5 or more. When the cut resistance of the fiber was repeatedly evaluated, it was found that the measurement was uneven and a stable and high evaluation could not be obtained, resulting in lack of reproducibility.

Therefore, in order to solve the above problem, the present inventors have studied in detail the shape (multi-angle) of hard particles. As a result, it was found that when the multi-angle represented by the Hausner surface index (details will be described later) is as high as 1.06 or more, stable and high cut resistance can be obtained. According to Hausner's surface index, the number increases as the shape deviates from the circle. However, it was also found that when the surface index becomes too high, for example, 10 or more, the specific surface area increases, hard particles aggregate, and the spinning nozzle is clogged. Therefore, the present inventors have further studied in order to obtain a polyethylene fiber having both stable and high cut resistance and hard particle agglutination resistance (no clogging of the spinning nozzle). As a result, they have found that the above problems can be solved by appropriately controlling both the surface index and the specific surface area of the hard particles contained in the polyethylene fiber, and completed the present invention.

The usefulness of the configuration of the present invention will be described in more detail based on the results in Table 1 described later.

First, Comparative Examples 2 to 4 in Table 1 correspond to Examples 1 to 3 of Patent Document 4, respectively, and are examples in which alumina having an average minor axis of 0.5 μm is used as the hard particles. These are examples in which the content of alumina contained in the polyethylene fiber is different, but the specific surface area is large. When the incision resistance and the stability of the incision resistance were evaluated for the above comparative examples based on the evaluation method described in the examples described later, generally good results were obtained in terms of incision resistance. However, it was found that the stability of cut resistance was significantly reduced.
Further, when the hard particle cohesiveness resistance of the above comparative example was evaluated based on the evaluation method described in the examples described later, clogging of the spinning nozzle occurred.

Further, Comparative Example 1 in Table 1 is an example in which silica having an average minor axis of 2.0 μm and Hauser's surface index = 1.01 is used as the hard particles. In Comparative Example 1 above, the spinning nozzle was not clogged, but since substantially circular silica was used, the stability of cut resistance was significantly reduced as in Comparative Examples 2 and 4.

The results of the above comparative example show that even hard particles conventionally disclosed as having excellent cut resistance have variations in cut resistance, are inferior in reproducibility, and cannot obtain stable cut resistance. It clearly shows that.

The same result as in Comparative Example 1 was also observed when the material of the hard particles was changed.
That is, Comparative Example 6 in Table 1 is an example in which glass having an average minor axis of 5.0 μm and Hauser's surface index = 1.02 was used as the hard particles. In Comparative Example 6 above, the spinning nozzle was not clogged, but since a substantially circular glass was used, the stability of cut resistance was significantly reduced as in Comparative Examples 2 and 4.
Further, Comparative Example 7 in Table 1 is an example in which glass having an average minor axis of 0.3 μm and a Hauser surface index of 1.32 is used as the hard particles. Since the material of Comparative Example 7 having a large specific surface area was used as in Comparative Examples 2 to 4, the stability of cut resistance and the agglomeration resistance of hard particles were remarkably lowered, and the spinning nozzle was clogged. ..

On the other hand, Examples 1 to 7 in Table 1 are examples in which various glasses having different average minor diameters are used as hard particles and the surface index and specific surface area are controlled within the range of the present invention, and the cut resistance is high. Both stability and hard particle agglutination resistance (no clogging of the spinning nozzle) are improved. Therefore, according to the present invention, it can be seen that it is possible to provide a polyethylene fiber capable of stably exhibiting high cut resistance with good reproducibility and suppressing agglutination of hard particles.

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 performance 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 have a repeating unit substantially as 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, these copolymers may be used together, or 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 provides the above stability. However, if the content other than ethylene increases too much, it will hinder drawing, so 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 contains a plurality of hard particles. The hard particles in the present invention include at least hard particles having an aspect ratio of less than 3, a Hauser surface index of 1.06 or more represented by the following formula, and a specific surface area of 5.0 m ² / g or less.
Hauser surface index = P ² / 4πA
During the ceremony
P is the perimeter (μm) of the particle projection image,
A is the area of the particle projection image (μm ² ).

In particular, the hard particles used in the present invention are characterized in that the surface index of Hausner represented by the above formula is 1.06 or more and the specific surface area is 5.0 m ² / g or less. , The desired effect is exhibited.

First, the hard particles used in the present invention satisfy Hauser's surface index of 1.06 or more. Here, Hausner's surface index is an index representing multiple angles of particles, and was first adopted by the present inventors as an index for evaluating the stability of cut resistance. According to Hausner's surface index, it is calculated as circle = 1, regular octagon ≒ 1.055, regular hexagon ≒ 1.103, square ≒ 1.273, equilateral triangle ≒ 1.654, and the numerical value increases as the shape deviates from the circle. Will be higher.

When the surface index of Hausner is less than 1.06, the effect of improving the stability of cut resistance is not effectively exhibited. On the other hand, when the surface index of Hausner exceeds 10, the specific surface area becomes large, and a new problem arises that hard particles tend to aggregate. Aggregation of hard particles causes clogging of the filter of the spinning nozzle, so that undrawn yarn cannot be obtained. Hausner's surface index is preferably 1.25 or higher, more preferably 1.30 or higher, and even more preferably 1.40 or higher. If the surface index of Hausner becomes too large, the specific surface area may increase and the spinning nozzle may be clogged as described above. Therefore, for example, 10 or less is preferable, and 5 or less is more preferable.

Further, the specific surface area of the hard particles used in the present invention ^{satisfies 5.0 m 2} / g or less. The range of the specific surface area is used as an index for suppressing agglutination of hard particles. If the specific surface area ^{exceeds 5.0 m 2} / g, the hard particles tend to aggregate and clogging occurs during spinning. The specific surface area is preferably 4.5 m ² / g or less, more preferably 3.0 m ² / g or less, ^{still more preferably 2.0 m 2} / g or less. On the other hand, if the specific surface area becomes too small, the filler size becomes large and the problem of thread breakage occurs. The specific surface area is preferably 0.02 m ² / g or more, more preferably 0.6 m ² / g or more.

Further, the aspect ratio of the hard particles used in the present invention is less than 3. 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 aspect ratio is preferably 1 or more and 2 or less. Here, the aspect ratio of hard particles represents the shape of particles defined by a value calculated based on JIS8900-1 (that is, (width orthogonal to maximum diameter / maximum diameter) in a microscope image of particles). Index). The method for measuring the aspect ratio of hard particles will be described in detail in the column of Examples described later.

The average minor axis of the hard particles used in the present invention is preferably 1.0 μm or more. If the average minor axis is less than 1.0 μm, the specific surface area increases and the hard particles aggregate as an aggregate, causing clogging during spinning. On the other hand, when the average minor axis of the hard particles becomes large, the filtration filter is clogged at the time of spinning, the productivity of the fiber is remarkably lowered, and the stretchability is particularly significantly lowered. Therefore, it is preferably 20 μm or less. The average particle size of the hard particles is more preferably 2 μm or more, further preferably 3 μm or more, and more preferably 10 μm or less.
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 are preferably silicon compounds. 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. More preferably, hard particles _{containing 20% by mass or more of SiO 2} are used, and examples thereof include silica and glass. More preferably, it is glass. Silica and glass are mainly distinguished by the content _{of SiO 2.} Silica is substantially composed of SiO ₂ only, and the SiO ₂ content of silica is approximately 95% by mass or more. On the other hand, the main component of glass is generally SiO ₂ , and in addition, alumina, B ₂ O ₃ , P ₂ O _{5 in} general, and the like may be included. _{The SiO 2} content in the glass is approximately 50% by mass or more.

The shape of the glass used in the present invention is not particularly limited as long as the above requirements are satisfied, and either glass fiber or glass frit is used. Here, the glass fiber has an average minor axis of approximately 4 to 12 μm, and in the present invention, both glass fiber (long glass fiber) and glass wool (short glass fiber) can be used. The glass frit is in the form of flakes or powder with an average minor axis of approximately 1.0 to 5.0 μm.

The hard particles used in the present invention preferably have a Mohs hardness of 4.5 or more. If the Mohs hardness is less than 4.5, hard particles do not hinder the blade during cutting, and it is difficult to obtain the effect of improving cutting resistance. However, if the Mohs hardness becomes too high, the machine base of the extruder or the like may be damaged, so the Mohs hardness is preferably 8.0 or less.
The hard particles satisfying the preferable range described above, for example, glass (which varies depending SiO ₂ content, if SiO ₂ content of about 50%, Mohs hardness of about 4.5 to 5.5), silica (Mohs hardness of about 6), titanium alone (Mohs hardness of about 6), and the like can be mentioned.
The Mohs hardness of titanate is about 4, and the Mohs hardness of alumina is about 9, which does not satisfy the above preferable range.
Regarding the method for measuring the Mohs hardness of the above-mentioned hard particles, it is generally difficult to measure the Mohs hardness with a filler. The Mohs hardness was estimated based on whether the standard sample was scratched by matching and rubbing against a standard sample of the Mohs hardness tester.

The plurality of hard particles contained in the polyethylene fiber of the present invention may be used as they are or those having a modified surface 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 and the like can be applied.

The preferable content of the plurality of hard particles contained in the entire polyethylene fiber of the present invention is 2% by mass or more, more preferably 5% by mass or more, still more preferably 10% by mass or more, and preferably 30% or more. It is less than mass%. When the content of the hard particles is less than 2% 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. However, if the content of the hard particles is too large, there is a problem such as yarn breakage during spinning and drawing, so the upper limit thereof is preferably, for example, 30% by mass or less.

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 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 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 not only the productivity is low, but also due to the use of a solvent. The impact on the health and environment of manufacturing workers, and the solvent remaining in the fiber has a large 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, 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 by using a fixed quantity supply device. 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 and 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, discharges 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 wound at least once at a temperature equal to or lower than the melting point of the undrawn yarn. Stretch 1.2 times or more. Specifically, it is preferable to carry out 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 viscoelasticity. 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 in logarithm, 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 total draw ratio is preferably 6 times or more, 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 a glove.

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 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 lines, 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 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 [η]
The ultimate viscosity was measured using a decalin heated to 135 ° C. as a solvent and using an Ubbelohde type capillary viscosity tube. 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 is divided or cut into about 5 mm lengths, 1% by mass of an antioxidant (Yoshinox BHT®, manufactured by Yoshitomi Pharmaceutical Co., Ltd.) is added to the polymer, and the temperature is 135 ° C. for 4 hours. The measurement solution was prepared by stirring and dissolving.

(2) Multi-angle of hard particles (Hausner's surface index)
The multi-angle of hard particles was calculated based on the Hausner surface index described above. Specifically, P (perimeter of the projected particle image, μm) and A (area of the projected particle image, μm ² ) of each hard particle were measured and calculated as follows.

First, each fiber sample prepared by the method described later is placed in a crucible, burned until it becomes ash and a carbonaceous substance, then placed in an electric furnace and heated at a polyethylene decomposition temperature (specifically, 480 ° C.) or higher. bottom. When the carbonaceous material was completely ashed, it was allowed to cool to room temperature in a desiccator to obtain ash. The hard particles contained in the ash thus obtained were observed at a magnification of 500 to 1500 using an industrial microscope (Olympus Corporation, BX53M). Of these, 20 hard particles were randomly extracted, and the area A of each hard particle and its peripheral length P were measured using the analysis software (STREAM) attached to the industrial microscope, and the above formula was used. Based on this, the surface index of Hausner was calculated. In this example, the average value of the above 20 surface indexes was calculated and used as the surface index of each fiber sample.

(3) Specific Surface Area of Hard Particles About 10 g of the ash obtained by the method of (2) above was collected, vacuum dried at 300 ° C. for 10 hours, and then weighed. Using the automatic specific surface area device of ASAP2020 manufactured by Micromeritix, the amount of nitrogen gas adsorbed at the boiling point of liquid nitrogen (-195.8 ° C.) is gradually increased in the range of relative pressure of 0.05 to 0.3. While measuring 40 points, an adsorption isotherm was prepared. Using the analysis software (GEMINI-PCW version 1.01) attached to the specific surface area device, set the surface area analysis range to 0.01 to 0.15 under BET conditions, and set the BET specific surface area [m ² / g]. I asked.

(4) Aspect ratio of hard particles The aspect ratio of hard particles was determined by using an SEM photograph. Specifically, each fiber sample prepared by the method described later 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 equal to or higher than the decomposition temperature of polyethylene. When the carbonaceous material was completely ashed, it was allowed to cool in a desiccator to obtain ash to room temperature. An SEM photograph of the ash thus obtained was 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 were measured, and the maximum major axis was set to the maximum. The aspect ratio was calculated by dividing by the width orthogonal to the major axis and obtaining the average value. Since the hard particles have high hardness, it is considered that the shape does not change even when heated.

(5) Average minor axis of hard particles For the average minor axis of hard particles, an SEM photograph was 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. , It was calculated by finding the average value.

(6) Content of hard particles The content of hard particles was determined by using ash content measurement based on JIS-2272. Specifically, 1.0 g of each fiber sample prepared by the method described later 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 equal to or higher than the decomposition temperature of polyethylene. After the carbonaceous substance was completely turned into ash, it was allowed to cool to room temperature in a desiccator and its 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 sample amount.

(7) 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 SODEMAT). 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. 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 380 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. The above tests were performed in 10 sets, and the average Index value (index value) of the 10 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.
K = (count value of cotton cloth before sample test + count value of cotton cloth after sample test) / 2
Index value = (sample count value + K) / K

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 5N for evaluation.

In this example, the index value obtained in Comparative Example 1 is set as the cut resistance 100, and this is used as a reference value, and each of the other examples shown in Table 1 shows the cut resistance as a relative ratio to the Comparative Example 11. bottom. For example, the cut resistance of Example 1 is 110, which means that when the cut resistance of Comparative Example 1 is 100%, a high cut resistance of 110% (1.1 times) is obtained. means.

(8) Stability of cut resistance The coefficient of variation CV value (= standard deviation / average value) in the 10 sets of tests performed in the cut resistance evaluation of (7) above was obtained and evaluated according to the following criteria.
CV value 25% or less: Excellent cut resistance stability (〇)
CV value over 25%: Poor cut resistance stability (×)

(9) Hard particle agglutination resistance The hard particle agglutination resistance was evaluated by the presence or absence of clogging of the spinning nozzle.

(10) Average Strength of Fibers The average strength of each fiber sample prepared by the method described below was calculated as follows.
Obtained by measuring the strain-stress curve under the conditions of sample length 200 mm (chuck length), elongation rate 100% / min, atmospheric temperature 20 ° C., and relative humidity 65% using "Tencilon" manufactured by Orientic. The strength (cN / dtex) was calculated from the stress at the break point of the curve, and the elastic modulus (cN / dtex) was calculated from the tangent line giving the maximum gradient near the origin of the curve. The same operation was performed 10 times, and the average value was taken as the average strength of each fiber sample.

(Example 1)
78% by mass of polyethylene pellets with an ultimate viscosity of 1.9 dL / g and glass fibers (E glass; main component) with an aspect ratio of 2.1, an average minor axis of 7.0 μm, and an average major axis of 16.0 μm as hard particles. A blended polymer was prepared by mixing 53% by mass of SiO _{2 and 15% by mass of Al 2} O ₃ ) with 3.0% by mass. The aspect ratio of the hard particles was an average of 10 particles as described above, and the range was 1.05 to 6.0. 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 30 H 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 retention section of 10 cm, cooled at 18 ° C. and 0.5 m / sec quenching, 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 knit was produced by the above method, and the cut resistance, the stability of the cut resistance, and the hard particle cohesiveness were 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.

(Examples 2 to 7, Comparative Examples 1 to 6)
Under the conditions of Example 1, the drawn yarn of the above example was obtained in the same manner as in Example 1 except that the material, average minor diameter, aspect ratio, and content of the hard particles were changed as shown in Table 1. The characteristics were evaluated. These results are shown in Table 1.

Here, the details of the glass used in Examples 2 to 7 are as follows.
Example 2: Glass fiber having an average minor axis of 7.0 μm and an average major axis of 16.0 μm (E glass; 53% by mass _{of SiO 2} and 15% by mass of _{Al 2} O _{3 as main components) 18.0 mass} %
Example 3: Glass frit with an average minor axis of 1.3 μm (E glass; 53% by mass _{of SiO 2} and 15% by mass of _{Al 2} O _{3 as main components) 18.0% by mass}
Example 4: Glass frit with an average minor axis of 3.5 μm (containing 53% by mass _{of SiO 2} and 20% by mass of _{Al 2} O _{3 as main components) 18.0% by mass.}
Example 5: Glass frit with an average minor axis of 3.5 μm (containing 60% by mass _{of SiO 2} and 7% by mass of _{B 2} O _{3 as main components) 6.0% by mass}
Example 6: Glass fiber having an average minor axis of 4.0 μm and an average major axis of 8 μm (glass wool, _{60% by mass of SiO 2} as a main component) 3.0% by mass
Example 7: Glass fiber having an average minor axis of 10.0 μm and an average major axis of 25.0 μm (E glass; 53% by mass _{of SiO 2} and 15% by mass of _{Al 2} O _{3 as main components) 6.0 mass} %

Further, Comparative Example 1 is an example simulating Example 1 (only the content is different) of Patent Document 4 described above.

As can be seen from Table 1, Examples 1 to 7 using polyethylene fibers satisfying the requirements of the present invention are excellent not only in cut resistance but also in cut resistance stability and hard particle agglomeration resistance. .. On the other hand, in Comparative Examples 1 to 7 which did not satisfy any of the requirements of the present invention, at least one of incision resistance stability and hard particle cohesion resistance was lowered.
Here, Comparative Example 5 is an example in which the average minor axis of the hard particles exceeds a preferable upper limit, and clogging occurs during spinning, so that an undrawn yarn could not be obtained. Therefore, the characteristics such as the strength of the fiber sample could not be evaluated.

Since the polyethylene fiber of the present invention is excellent not only in high cut resistance but also in cut resistance stability and hard particle agglutination resistance, cut resistance woven and knitted fabrics utilizing these characteristics, such as gloves and It can be used for vests, etc. 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 thread, artificial tendon, artificial muscle , Fiber reinforced resin reinforcing material, cement reinforcing material, fiber reinforced rubber reinforcing material, machine tool parts, battery separator, chemical filter 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 (10)

A polyethylene fiber containing hard particles having an aspect ratio of less than 3, a Hausner surface index represented by the following formula of 1.06 or more, and a specific surface area of 5.0 m ^{2 / g or less.}
Hauser surface index = P ² / 4πA
During the ceremony
P is the perimeter (μm) of the particle projection image,
A is the area of the particle projection image (μm ² )
Is. The polyethylene fiber according to claim 1, wherein the hard particles are silicon compounds. The polyethylene fiber according to claim 1 or 2, wherein the hard particles _{contain 20% by mass or more of SiO 2 in the hard particles.} The polyethylene fiber according to any one of claims 1 to 3, wherein the average minor axis of the hard particles is 1.0 μm or more. The polyethylene fiber according to any one of claims 1 to 4, wherein the hard particles have a Mohs hardness of 4.5 or more. The polyethylene fiber according to any one of claims 1 to 5, 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 any one of claims 1 to 6, wherein the polyethylene fiber contains 2% by mass or more of the hard particles. A product comprising the polyethylene fiber according to any one of claims 1 to 7. The product according to claim 8, wherein the product is a cut-resistant knitted fabric. The product according to claim 8 or 9, wherein the product is a glove.