JPH11350247A - High-strength polyethylene fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a high-strength polyethylene fiber with extremely slight change in their physical properties even if subjected to temperature change, therefore suitable to various applications. SOLUTION: This high-strength polyethylene fiber is such one as to consist mainly of ethylene component, having the following physical properties: intrinsic viscosity [ηF]: >=5, tenacity: >=25 g/d, modulus: >=800 g/d, the peak temperature of the loss modulus of γ-dispersion in the temperature dispersion measurement for dynamic viscoelasticity: <=-110 deg.C, and the peak temperature of the loss modulus of α-dispersion: >=100 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to protective clothing and sports clothing, such as various ropes, fishing lines, nets and sheet materials for civil engineering and construction, fabrics and nonwoven fabrics for chemical filters and separators, bulletproof vests, helmets and the like. High-strength polyethylene fiber that can be used widely in industrial materials and textile applications, such as impact-resistant composites and reinforcing materials for sports composites, and its performance changes with temperature under conditions where it is used in environments with large temperature changes. More particularly, the present invention relates to a high-strength polyethylene fiber having little temperature change in mechanical properties such as strength and elastic modulus.

[0002]

2. Description of the Related Art In recent years, attempts have been made to obtain high-strength and high-modulus fibers from ultrahigh-molecular-weight polyethylene as a raw material, and fibers having very high strength and elastic modulus have been reported. For example, JP-A-56-15408 discloses that
There is disclosed a so-called "gel spinning method" in which a gel fiber obtained by dissolving ultrahigh molecular weight polyethylene in a solvent is drawn at a high magnification.

[0003] It is known that high-strength polyethylene fibers obtained by the "gel spinning method" have very high strength and elastic modulus as organic fibers, and are also extremely excellent in impact resistance. Its applications are expanding.
For the purpose of obtaining such high-strength fibers, Japanese Patent Application Laid-Open No. 56-15408 discloses that it is possible to provide a material having extremely high strength and elastic modulus. On the other hand, however, high-strength polyethylene fibers are known to have a very large change in performance with temperature. For example, when the tensile strength is measured by changing the temperature from around -150 ° C., the decrease is gradually observed as the temperature rises from a low temperature, and especially at room temperature or higher, especially a relaxation mechanism called crystal dispersion is observed. The performance declines remarkably from the vicinity. Such a change in performance due to temperature has made it difficult to use this material in an environment where the temperature changes greatly.

Conventionally, as an attempt to control a change in mechanical properties of such a high-strength polyethylene fiber due to a temperature change, as disclosed in JP-A-7-166414, an ultra-high molecular weight having a specific molecular weight has been disclosed. Attempts have been made to improve the vibration absorption in the so-called cryogenic region at -100 ° C or lower by adjusting the molecular weight of the polyethylene raw material and the resulting fiber to an appropriate range. In, the mechanical dispersion at extremely low temperatures is increased.
In other words, it is rather an attempt to increase the change in elastic modulus,
This was contrary to the attempt of the present invention to reduce the decrease in mechanical properties.

Further, JP-A-1-156508 and JP-A-1-162816 have attempted to reduce the creep of high-strength polyethylene fibers by means of peroxide or ultraviolet irradiation in the above gel spinning method. It has been disclosed. Basically, according to the present method, the dynamic dispersion of the above-mentioned γ dispersion is described to be low, which is a preferred direction described by the present invention, but both inventions aim to improve the creep of high-strength polyethylene fibers, It did not reduce the change in mechanical properties due to temperature changes. In particular, when the relaxation strength in the normal γ dispersion decreases, the temperature at which the relaxation occurs usually shifts to a high temperature, and the conventional method requires that the change in mechanical properties with respect to the change in temperature is smaller than the target of the present invention. In other words, it was the opposite direction because the γ dispersion temperature is preferably lower and the α dispersion is preferably higher.

[0006]

SUMMARY OF THE INVENTION Based on the above viewpoints,
The present invention has extremely excellent mechanical properties at room temperature, and
It is an object of the present invention to provide a high-strength polyethylene fiber having little change in mechanical properties such as strength and elastic modulus due to temperature change.

[0007]

That is, the present invention relates to a polyethylene fiber mainly composed of an ethylene component having an intrinsic viscosity [ηF] of 5 or more in a fiber state, having a strength of 25 g / d or more and an elastic modulus of 800 g. / D or more, and the peak temperature of the loss elastic modulus of γ dispersion in the temperature dispersion measurement of the dynamic viscoelasticity of the fiber is −110 ° C. or less, and the peak temperature of the loss elastic modulus of α dispersion is 100 ° C. or more. It is a high-strength polyethylene fiber characterized by the following.

The ultrahigh molecular weight polyethylene in the present invention is characterized in that its repeating unit is substantially ethylene, and a small amount of another monomer such as α-olefin,
Copolymers with acrylic acid and its derivatives, methacrylic acid and its derivatives, vinylsilane and its derivatives, and the like, or copolymers of these copolymers, or copolymers with ethylene homopolymer, and other α -It may be a blend with a homopolymer such as an olefin.
In particular, it is more preferable to use a copolymer with an α-olefin such as propylene or butene-1 so as to contain short-chain branches to some extent, because this gives stability in spinning and drawing when producing the present fiber. However, if the content other than ethylene is excessively increased, it becomes a hindrance factor of stretching. Accordingly, from the viewpoint of obtaining high-strength and high-modulus fibers, the content is preferably 5 mol% or less in monomer units. Of course, a homopolymer of ethylene alone may be used.

The skeleton of the present invention has a peak temperature of a loss elastic modulus of γ dispersion in temperature dispersion of dynamic viscoelastic properties measured in a fiber state of −110 ° C. or less, preferably −115 ° C. or less, Peak temperature of loss modulus of
C. or higher, preferably 105.degree. C. or higher. High-strength polyethylene fibers having such characteristics have extremely high mechanical properties at room temperature and little change in the mechanical properties over a wide temperature range.

The small change in performance of the present fiber due to the temperature can be definitely defined by two kinds of mechanical dispersion temperatures, namely, α and γ dispersion temperatures. That is, a remarkable decrease in the elastic modulus is usually observed in a temperature range where the mechanical dispersion occurs. In the case of a high-strength polyethylene fiber, a γ dispersion is usually observed around -100 ° C, and an α dispersion is observed around 85 ° C.
When the fiber is used with the temperature between the two, the ordinary temperature causes an extremely large change in the elastic modulus and the strength every time the temperature passes through the vicinity thereof, which is not preferable in designing various products. Therefore, the temperature region is usually set above the γ dispersion temperature and below the α dispersion temperature with some allowance taken into consideration, and the use temperature region is determined. Therefore, it is very significant that the γ dispersion temperature is lower and the α dispersion temperature is higher in the sense of expanding the above-mentioned use temperature range.

It is extremely surprising from the common sense that the peak temperature of γ dispersion is extremely low, contrary to the fact that the α-dispersion temperature is high as in the present fiber. That is, it is known that the amorphous dispersion and the crystal contribution originally contribute to the γ dispersion. In conventional high-strength polyethylene fibers, it is possible to relatively easily shift α-dispersion to a higher temperature by increasing the draw ratio or promoting crystallization. This suggests that the fine structure of the yarn becomes more crystalline. In this case, the structure governing the γ dispersion also shifts from amorphous to crystalline, and the temperature of the γ dispersion usually shifts to a high temperature. In other words, it can be said that the fiber provided in the present invention is contrary to conventional common sense also in microstructure. Further, the peak temperature of the α-dispersion of the present fiber is at least 100 ° C. or higher, preferably 105 ° C. or higher as compared with that of the conventional high-strength polyethylene fiber obtained by the above-described stretching or the like, which was at most about 95 ° C. Very hot. Even in the case of the γ-dispersion, it is difficult to lower the temperature below −110 ° C. in the case of a fiber having a high crystallinity usually having a temperature of 90 ° C. or higher, even if the fiber does not have the above-mentioned high α-dispersion temperature. Partly, for example, when the α dispersion temperature is 8
In the case of a fiber of about 5 ° C., the γ dispersion temperature may be −110 ° C. or less, which is because the fiber structure becomes more amorphous, and the high crystallinity (α dispersion temperature Is high) but the gamma dispersion temperature is still low and can be clearly distinguished.

The method for obtaining the fiber according to the present invention naturally requires a new and careful method, but is not limited to the following examples. That is, as a method for obtaining the present fiber, the above-mentioned "gel spinning method" is effective as a practical method, but any method for forming ultra-high molecular weight polyethylene to obtain a conventionally known high-strength polyethylene fiber can be used. In particular, the basic yarn-making technique is not limited. The important thing in the present invention is a polymer as a raw material.

That is, in the present invention, it is recommended to use two kinds of ultrahigh molecular weight polyethylene. At this time, the main polymer has an intrinsic viscosity of 5 or more, preferably 10 or more and less than 40, and is obtained by dissolving the polymer uniformly in solid paraffin having a solid at room temperature and a melting point of less than 100 ° C. 0.001sec when made into solution
The ratio of the shear viscosities measured at a shear rate of -1 and 0.01 sec-1 (i.e., the value obtained by dividing the former by the latter, hereinafter referred to as "viscosity index") is 5 or less, preferably 3.5 or less. 90 parts by weight or more of polymer (A) 9
Less than 9.9 parts by weight, intrinsic viscosity 20 or more, preferably 2
5 parts or more, more preferably 30 parts or more, of a mixture containing 0.1 to 10 parts by weight of a higher molecular weight polyethylene (B), and 100 parts by weight of the polymer mixture, By adding a soluble solvent in an amount of 100 parts by weight or more, heating the mixture, adding mechanical dissolution, dissolving, spinning, and then drawing, the fiber promoted for the above purpose can be obtained most efficiently.

The novel high-strength polyethylene fiber according to the present invention is characterized by a small change in performance with temperature, as described above, and this feature is characterized by two types of mechanical dispersion, namely α.
And the temperature of γ dispersion. Generally, it has been thought that γ dispersion originates from defects in local molecular chain structures such as molecular terminals and side chains. Usually, in the case of ultrahigh molecular weight polyethylene having almost no side chains as its molecular chain structure, it is considered that this contribution is mainly affected by molecular chain ends. The distribution of the molecular chain terminals in or around the crystal structure has not been well understood scientifically. According to the study of the inventor, it is recommended to use two kinds of ultra-high molecular weight polyethylene to achieve the above object. That is, first the intrinsic viscosity is 5 or more,
It is preferably 10 or more and less than 40, and has a viscosity index of 5 or less, preferably 3.5 or less when the polymer is dissolved in solid paraffin to obtain a 10% solution according to assumed dissolution conditions. Polymer (A) at least 90
To 99.9 parts by weight and an intrinsic viscosity of 20 or more, preferably 25 or more, and more preferably 3 or more.
100 parts by weight of a mixture containing 0.1 to 10 parts by weight of a higher molecular weight polyethylene (B) having 0 or more, and 100 parts by weight of a solvent substantially soluble in the polymer mixture The present invention was found to be able to increase the α-dispersion temperature while maintaining the above-mentioned γ-dispersion temperature at a low temperature, by adding and heating at least one part, heating and dissolving by adding mechanical mixing, spinning, and then stretching. .

Although the reason is only presumed, the fact that the viscosity index is 5 or less, preferably 3.5 or less suggests that the dependence of the viscosity under shear deformation on the shear rate is extremely small. Conversely, this suggests that molecules with a very uniform relaxation time are present in the solution flow (narrow distribution of the relaxation time), which results in a more uniform molecular chain when formed into a yarn. It is considered that the cause is that the molecules are arranged and the molecular terminal structure is uniformly arranged in or near the crystal. It is generally known that in ordinary polyethylene, the higher the crystallinity or the higher the draw ratio, the higher the γ dispersion temperature. Considering that this suggests that the molecular chain ends and the like are taken into the inside of the crystal and that its movement is suppressed, it is suggested that the γ dispersion temperature of this fiber is maintained at a relatively low temperature considering the above mechanism. It is. In other words, it is considered that local defects of polyethylene, mainly molecular chain terminals, are not taken into the interior of the crystal with crystallization or elongation, but rather are unevenly distributed around the periphery due to a specific alignment mechanism of some molecules. This also indicates that the temperature of α-dispersion, which represents crystal dispersion, becomes very high, which means that there are very few defects such as molecular ends inside the crystal and the crystal structure is more complete. Suggests that you have approached.

The preparation of an ultrahigh molecular weight polymer having a viscosity index of 5 or less, preferably 3.5 or less according to the present invention can be achieved by a number of means. First, a polymer having a very small molecular weight distribution is used. For example, an optimum polymer can be selected from polymers having a molecular weight distribution Mw / Mn of 5 or less. More preferably, Mw / Mn is 3 or less. In this case, for example, a polymer having a much narrower molecular weight distribution using a metallocene catalyst may be used. Furthermore, Mw / M of molecular weight distribution
Even in the case of a polymer using a so-called ordinary Ziegler-Natta catalyst in which n exceeds 5, when the polymer is dissolved, the intrinsic intrinsic viscosity of the polymer [η
A] and the intrinsic viscosity [ηF] after the fiber state satisfies the following formula, can almost satisfy the flow index required by the present invention.

[ΗA] × 0.60 ≦ [ηF] ≦ [ηA] × 0.85

That is, the ultra-high molecular weight polyethylene whose molecular weight distribution has been adjusted to almost the narrowest by a usual Ziegler-Natta catalyst is further deliberately reduced in the step of melting and extrusion to substantially reduce the substantial molecular weight distribution. Can be narrow. At this time, it is natural that a formulation such as adding a decomposition accelerator such as a peroxide compound or dissolving active oxygen in a solution is efficient, without using an antioxidant in the dissolving step. As described above, when the molecules are intentionally degraded in the process, the probability that the high molecular weight side is cut is high, and it can be expected that the molecular weight distribution is statistically narrowed.
On the other hand, the demand in the present invention lies in its fluidity index, and a fluidity modifier or a very small amount of polymer may be added to obtain a desired fluidity index, and a fluidity such as an ionic coagulant or a metal stearate may be obtained. Modifiers are one example of these.

Further, in the present invention, the main polymer (A)
With respect to the intrinsic viscosity of a small amount of 20 or more, preferably 25
As mentioned above, it is more preferable to add a high-molecular-weight polyethylene having 30 or more. The gist of this is that even if the main polymer A alone can be used to obtain a fiber with little change with respect to temperature, it is difficult to obtain a high-strength fiber, and in particular, the drawability of the molecule is significantly deteriorated in the spinning and drawing processes. As a result of intensive studies, the intrinsic viscosity was 20
Above, preferably 25 or more, more preferably 30 or more, when a very high molecular weight polyethylene having a very small amount of 0.1 part by weight or more and less than 10 parts by weight is added, the deformation by spinning and drawing becomes remarkably good. On the other hand, it has been found that the temperature of α-dispersion becomes higher, and the mechanical properties, particularly the elastic modulus, are greatly improved, and the present invention has been reached.

Although the cause is not clear, a very small amount of the high molecular weight component B plays a role of minimum stress propagation in the spinning and drawing process, and the smooth deformation of the molecule in the spinning and drawing is likely to occur. I presume it is not, but it is not clear. The component B may be used in a very small amount, and if it exceeds 10 parts by weight, it is extremely difficult to perform stretching or the like, and it causes non-uniformity in dissolution or the like. On the other hand, if the amount is less than 0.1 part by weight, the effect of improving the moldability and thermally stabilizing becomes insufficient.

The fiber obtained by the above method or the like has an intrinsic viscosity [ηF] in a fiber state of 5 or more, preferably 10 or more and less than 40, and has a strength of 25 g / d or more, preferably 30 g / d or more. , More preferably at least 35 g / d, and the elastic modulus is at least 800 g / d, preferably at least 1000 g / d.
As described above, it is more preferably 1200 g / d or more, and the synergistic effect with the above-mentioned dynamic dispersion characteristics makes it possible to provide a polyethylene fiber having extremely excellent characteristics which has not been achieved conventionally in practical use.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The measuring method and measuring conditions relating to characteristic values in the present invention will be described below. (Dynamic Viscoelasticity Measurement) The dynamic viscosity measurement in the present invention is as follows.
Orientec's Leo Vibron DDV-01FP
Using a mold. The fibers are split or ligated so as to be 100 denier ± 10 denier as a whole, and the measurement length (distance between scissors metal fittings) is set to 20 mm in consideration of arranging each single fiber as uniformly as possible. Both ends of the fiber are wrapped with aluminum foil and adhered with a cellulosic adhesive. The glue margin length at that time is 5 mm in consideration of fixing with scissors metal fittings.
Degree. Each test piece was carefully set on a scissor fitting (chuck) set to an initial width of 20 mm so that the thread would not be loosened or twisted, and was preliminarily deformed for several seconds at a temperature of 60 ° C. and a frequency of 110 Hz. After that, this experiment was performed. In this experiment, the temperature dispersion at a frequency of 110 Hz was obtained from the lower temperature side at a rate of about 1 ° C./min in a temperature range of −150 ° C. to 150 ° C. In the measurement, the static load was set to 5 gf, and the sample length was automatically adjusted so that the fiber did not loosen. The amplitude of the dynamic deformation was set at 15 μm.

(Strength and Elastic Modulus) The strength and elastic modulus in the present invention were measured using "Tensilon" manufactured by Orientic.
A strain-stress curve was measured under the conditions of a sample length of 200 mm, an elongation rate of 100% / min, an atmosphere temperature of 20 ° C. and a relative humidity of 65%, and the stress at the break point of the curve was measured for strength (g / d). From the tangent line that gives the maximum gradient near the origin, the elastic modulus (g /
d) was calculated and determined. In addition, each value used the average value of 10 measured values.

(Intrinsic viscosity) The specific viscosities of various dilute solutions were measured using an Ubbelohde capillary viscometer with decalin at 135 ° C., and the straight line obtained by the least squares approximation of a plot of the concentration of the viscosity was calculated. The intrinsic viscosity was determined from the extrapolated point. At the time of measurement, if the raw material polymer is in the form of a powder, the sample is kept in that shape, and if the powder is a lump or a fibrous sample, the sample is divided or cut into lengths of about 5 mm, and 1 wt% of the polymer is oxidized. Inhibitor (trade name "Yoshinox BHT" manufactured by Yoshitomi Pharmaceutical Co., Ltd.)
The measurement solution was prepared by stirring and dissolving at 35 ° C. for 4 hours.

(Measurement of Shear Viscosity and Calculation of Viscosity Index)
The method for measuring the ballistic viscosity in this patent is described in detail below. First, 10 parts by weight of an ultrahigh molecular weight solid polymer and solid paraffin having a number average molecular weight of about 500 (the melting point is higher than room temperature and the number average molecular weight does not exceed 1000) (powder solid paraffin in this patent: trade name) 90 parts by weight of "LUVAX1266" (manufactured by Nippon Wax Co., Ltd.) and 1 wt% of an antioxidant (trade name "Yoshinox BHT" manufactured by Yoshitomi Pharmaceutical Co., Ltd.) depending on the conditions required for actually spinning the polymer )
Is added as much as possible to the dissolution conditions in actual spinning, for example, using a device such as a twin-screw kneader,
The mixture was mixed and dissolved at a high temperature, and the extruded material was cut into a pellet. The pellets thus obtained were filled into two pairs of flat molds having 2 mm spacers,
After leaving for 1 hour in a heating press machine set at 60 ° C., further leaving for 1 hour under a pressure of 200 kgf / cm ² , it was quenched with ice water to prepare a test piece. This test piece is cut into a size that can be filled in a cone plate type viscoelasticity measuring device (ARES, Rheometrics), and the shear rate is 0.001 s in a dynamic mode at 160 ° C.
The complex dynamic viscosities at ec-1 and 0.01 sec-1 were determined, and the value obtained by dividing the former by the latter was adopted as the viscosity index. The measurement is an average value of the results obtained by randomly selecting and measuring 10 points from the pressed test side.

Hereinafter, the present invention will be described with reference to examples. (Example 1) 98 parts by weight of a main component polymer (C) of an ultrahigh molecular weight polymer having an intrinsic viscosity of 18.5 and a molecular weight distribution Mw / Mn of 5.5, an intrinsic viscosity of 30, and a molecular weight distribution of A powdery mixture containing 2 parts by weight of a polymer (D) having about Mw / Mn = 12.0 was 15% by weight of the total amount.
85% by weight of decahydronaphthalene was added at room temperature so that This polymer was melted and extruded with a biaxial mixing extruder at a temperature of 200 ° C. and 100 rpm. In this case, no antioxidant was used. In a preliminary experiment for performing this operation, 10% by weight and 90% by weight of the above-mentioned polymer (C) alone were mixed at 200 ° C. in a twin-screw kneader with solid paraffin at the same screw conditions (temperature and antioxidant). Was added, and the pellet was cooled and granulated, and the viscosity index was calculated by the above-described evaluation method, and the value was 3.2.

After dissolving such a polymer under the above conditions,
The orifice having a diameter of 0.8 mm is extruded using a base provided with 48 holes so that the discharge rate of each hole is 1.6 g / min. While removing, pick-up was performed at a speed of 90 m / min. The drawn yarn is immediately stretched 5 times in an oven at 120 ° C., then wound up once, and then 149 times.
The film was drawn 4.5 times in an oven adjusted to a temperature of ° C. to obtain a high-strength fiber. Table 1 shows various physical properties of the obtained fiber, including dynamic viscoelastic properties.

Example 2 A drawn yarn was obtained in the same manner as in Example 1 except that the polymer (E) having an intrinsic viscosity of 22 was used as the main component polymer, and the flow index was evaluated. Compared with Example 1, stretching was extremely smooth, and high-strength fibers could be obtained. The viscosity index of Polymer E was 2.9, which was a better value.

Example 3 The ratio of the main component polymer (C) to the ultrahigh molecular weight component polymer (D) in Example 1 was 9
A drawn yarn was obtained by substantially the same operation except that the amount was changed to 9.5 parts by weight and 0.5 part by weight. The flow index of the polymer is 3.1
And was equivalent to Example 1 within the range of experimental error. As shown in Table 1, the strength was slightly lowered due to poor stretchability, and the γ dispersion temperature was slightly higher, but relatively satisfactory results were obtained.

(Example 4) An ethylene polymer comprising zirconium metallocene as a main component polymer in Example 1, having an intrinsic viscosity of 18.5 and Mw / Mn = 2.
An experiment was performed to obtain a drawn yarn by the same operation as in Example 1 except that the polymer (F) of No. 7 was used. The fluidity index of the polymer (F) was 1.9, which was an extremely excellent property, and the physical properties of the drawn yarn were as shown in Table 1.
Although the reason is not well understood, the elastic modulus showed a particularly high value when compared with Example 1. Very good results were also obtained in dynamic viscoelastic properties.

Example 5 In Example 4, when the polymer was dissolved, 1 wt% was added to the total amount of the blended polymer.
An experiment was conducted to obtain a drawn yarn by the same operation except that BHT was added to the mixture. The flow index performed according to the dissolution method in which the additive was formulated was slightly increased to 2.1, but was excellent. Although the properties of the obtained fiber were lower than those in Example 4, the elastic modulus with respect to the strength seen in Example 4 tended to increase. Excellent results were also obtained for the dynamic viscoelastic properties.

COMPARATIVE EXAMPLE 1 Except for using the main component polymer (C) of Example 1, no high molecular weight substance was added. Polymer C The flow index of the polymer itself was naturally as good as that of Example 1, and although excellent values were obtained in strength and elastic modulus, the γ dispersion temperature was relatively high, and the α dispersion temperature was relatively low. Fibers with little change in physical properties over a wide range of temperatures which the patent aimed at could not be obtained.

Comparative Example 2 A high molecular weight compound was not added except that the main component polymer (F) was used in Example 4. The flow index of the polymer F itself is naturally very good, equivalent to that of Example 4. However, remarkable yarn breakage occurs in the process of drawing and spinning, and a sufficient length (for example, 100
Judgment is made based on continuous winding of 0 m or more. ) Was not obtained. Table 1 shows the physical properties of the fiber that could be wound for a very short time. Although the values of strength and elastic modulus were reasonable, a fiber having a high γ-dispersion temperature and a low α-dispersion temperature as in Comparative Example 1 and having little change in physical properties at a wide range of temperatures which this patent aims at is obtained. I couldn't do that.

Comparative Example 3 In Example 1, when the polymer was dissolved, 1 wt.
An experiment was conducted to obtain a drawn yarn by the same operation except that BHT was added to the mixture. A high flow index of 5.2 was obtained in accordance with the dissolution method in which the additive was formulated. As indicated by the fluidity index, spinning and drawing caused yarn breakage at a very high frequency, and it was not possible to obtain continuous fibers of a sufficient length, nor was it possible to collect them in a short time. 2
Table 1 shows the physical properties of the fibers obtained in a short time by reducing the step stretching ratio to 2.5 times. Only a low level of drawn yarn could be obtained in all of the strength, elastic modulus and dynamic viscoelastic properties.

[0035]

[Table 1]

[0036]

As described above, it has become possible to provide a high-strength polyethylene fiber suitable for various uses in which the change in fiber properties with temperature change is extremely small.

Claims (1)

[Claims] 1. A polyethylene fiber mainly composed of an ethylene component having an intrinsic viscosity [ηF] of 5 or more in a fiber state,
The strength is 25 g / d or more, the elastic modulus is 800 g / d or more, and the peak temperature of the loss elastic modulus of γ dispersion in the temperature dispersion measurement of the dynamic viscoelasticity of the fiber is −110 ° C. or less, and α The peak temperature of the loss modulus of dispersion is 10
A high-strength polyethylene fiber having a temperature of 0 ° C. or higher.