JP2992323B2 - High molecular weight polyethylene molecular orientation molding - Google Patents

Abstract

PURPOSE:To obtain the subject molecularly oriented molded body, composed of high-molecular weight polyethylene, having a prescribed relation among tensile strength, weight-average molecular weight and size and excellent in strength with hardly any deterioration in tensile strength even when subjected to corona discharge treatment. CONSTITUTION:A molecularly oriented molded body is composed of a molecularly oriented molded body of high-molecular weight polyethylene having 300000-600000 weight-average molecular weight. The aforementioned molded body has <=15 denier size and >=1.7 GPa tensile strength. The tensile strength [S (GPa)], the weight-average molecular weight [M (g/mol)] and the size [D (denier)] thereof satisfy the relation expressed by the formula.

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a molecularly oriented molded product of high molecular weight polyethylene.

Technical Background of the Invention Conventionally, when producing polyethylene fibers having excellent tensile strength of 1.7 GPa or more, the molecular weight is about
Ultra-high molecular weight polyethylene of 1,000,000 or more has been used. It is thought that this is mainly due to the fact that the end of the molecule in the fiber structure becomes a structural defect and causes the tensile properties, especially the tensile strength to decrease, so that the higher the molecular weight, the higher the strength of the fiber. It was thought that it could be obtained. For example, JP-A-63-66316 discloses a method of obtaining a gel filament from a dilute solution of ultrahigh molecular weight polyethylene having a molecular weight of 600,000 or more, and then obtaining a filament having excellent tensile properties by stretching the filament. Have been. In this gazette, specifically, ultrahigh molecular weight polyethylene having a molecular weight of about 1,500,000 is used as a raw material.

However, the higher the molecular weight of polyethylene, the lower its moldability. For example, by the method described in JP-A-63-66316,
When attempting to produce a filament having excellent tensile properties, the higher the molecular weight, the lower the solubility in a solvent or the viscosity of the solution at a given concentration becomes too high, and the filament breaks during the spinning or drawing process. Is more likely to occur. Therefore, in order to prevent such a phenomenon from occurring, when a polyethylene having an extremely high molecular weight is used, it is necessary to lower the concentration of the solution and to lower the spinning speed and the drawing speed to some extent. As described above, when the molecular weight of the raw material polyethylene is increased, a fiber having excellent tensile properties can be obtained, but on the other hand, the moldability is deteriorated, so that a decrease in industrial productivity cannot be avoided.

Ultra-high molecular weight polyethylene having a very high molecular weight is liable to undergo thermal degradation during molding. Therefore, it is considered that a certain degree of molecular weight reduction is inevitable at the time of raw material preparation or spinning, and carbonyl groups and the like are generated due to thermal deterioration, which adversely affects the weather resistance of the obtained polyethylene fiber.

By the way, the main use of polyethylene fiber having high strength is woven fabric. Such a woven fabric is specifically used for a reinforcing fiber, a bulletproof cloth, a cut-off protective garment, and the like, but when used for a composite reinforcing fiber, from the viewpoint of the weaving density at the time of weaving, adhesiveness, and the like. Further appearance of thin polyethylene fibers is desired, and when used for bulletproof cloth and cut protection, from the viewpoint of elasticity and cut resistance, appearance of polyethylene fibers having excellent strength and thinness is desired. Yes,
Further, from the viewpoint of bodily sensation, the appearance of fine fibers having an excellent touch is desired.

By the way, conventionally, it has been considered that ultrahigh molecular weight polyethylene having a molecular weight of at least 600,000 or more must be used as a raw material in order to obtain a polyethylene fiber having high strength. For example, JP-A-59-187614
The publication discloses a method for producing polyethylene fibers, but the polyethylene fiber having the highest strength obtained in the examples of the publication has a fiber diameter of 4.2 denier and 3.16 G
Pa. In order to obtain such a polyethylene fiber, a high molecular weight polyethylene having an intrinsic viscosity of 8.20 dl / g is used, and the molecular weight of this high molecular weight polyethylene is about 750,000 when its molecular weight is calculated from the intrinsic viscosity. Therefore, according to the conventionally widely accepted common sense that the strength of polyethylene fiber is proportional to the molecular weight of polyethylene used as a raw material, from a high molecular weight polyethylene having a weight average molecular weight of 600,000 or less, a strength of 3.16 GPa or more It is considered that a fiber having the following formula cannot be obtained.

By the way, a polymer polyethylene molecular orientation body may be used as a fiber for reinforcing a composite material. However, such a fiber for reinforcing a composite material is desired to have excellent adhesion between the fiber and the matrix. However, polyethylene is generally not very good in adhesiveness, and therefore, means for improving the adhesiveness has been adopted. As one of the methods, corona discharge treatment is known.

In a conventionally known molecular orientation body of high molecular weight polyethylene, when a corona discharge treatment is performed, the adhesiveness is improved, but the tensile strength may be largely reduced.

The present inventors have conducted intensive studies to break the above common sense, and found that the fineness (denier) can be reduced even with a high-molecular-weight polyethylene having a weight average molecular weight of 600,000 or less and excellent moldability. As a result, the present inventors have found that a polyethylene fiber having a small thickness and substantially no decrease in tensile strength even when subjected to corona discharge treatment and having excellent strength, that is, a polyethylene molecular oriented molded article, can be obtained, and the present invention has been completed.

Object of the Invention The present invention has been made in view of the above points, and has excellent moldability when producing a molecular alignment body, and hardly decreases the tensile strength even when subjected to corona discharge treatment. It is an object of the present invention to provide a high molecular weight polyethylene oriented body having excellent strength, for example, a high molecular weight polyethylene fiber.

SUMMARY OF THE INVENTION The high molecular weight polyethylene molecular orientation molded product according to the present invention is a high molecular weight polyethylene molded product comprising a high molecular weight polyethylene having a weight average molecular weight of 300,000 to 600,000, a fineness of 15 denier or less, and a tensile strength. Is at least 2.
0 GPa or more, and its tensile strength S (GPa), its weight average molecular weight M (g / mol) and its fineness D (denier) It is within a range that satisfies the relationship indicated by.

DETAILED DESCRIPTION OF THE INVENTION The high molecular weight polyethylene molecular oriented molded article according to the present invention will be specifically described below.

Raw material polyethylene The molecular orientation molded product obtained by the present invention has a weight average molecular weight of 300,000 to 600,000, preferably 350,000 to 600,00.
0, more preferably from high molecular weight polyethylene of 400,000 to 600,000. The weight average molecular weight of the high molecular weight polyethylene can be determined by calculation from the intrinsic viscosity measured with a decalin solution at 135 ° C.

The weight average molecular weight of the high molecular weight polyethylene used in the present invention is preferably not more than 600,000 from the viewpoint of stretch moldability, and if it is less than 300,000, the molecular orientation of the high molecular weight polyethylene having a strength of 1.5 GPa or more. It is difficult to obtain a molded article, and the resulting molecularly oriented molded article tends to have poor performance such as creep resistance and wear resistance. Note that Ch
anig is published in Journal of Polymer Science (vol. 36, 91 (195
According to the formula reported in 9)), the intrinsic viscosity of high molecular weight polyethylene having a molecular weight of 300,000 to 600,000 is in the range of 4.23 to 6.87.

The high molecular weight polyethylene used in the present invention may be a homopolymer of ethylene or a copolymer of ethylene and a small amount of α-olefin. When such a copolymer of ethylene and α-olefin is used, the ethylene content is usually 95 mol% or more, preferably 98 mol% or more.

As such an α-olefin, an α-olefin having 3 to 10 carbon atoms is usually used. Such α-
Specific examples of the olefin include propylene, 1-butene, 3-methyl-1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene,
-Octene or the like is used. In addition to the above-mentioned α-olefin, other copolymerization components such as a cyclic olefin may be copolymerized within a range that does not impair the properties of ethylene used in the present invention.

The molecularly oriented molded article according to the present invention has a weight average molecular weight of 300,000 to 600,000, and has a fineness of 15 denier or less, preferably 12 denier or less, and more preferably 10 denier or less. And has a tensile strength of at least 2.0 GPa or more,
Moreover, its tensile strength S (GPa) and its weight average molecular weight M
(G / mol) and its fineness (denier) are represented by the formula [I] Satisfies the relationship indicated by.

The oriented molecular product of high molecular weight polyethylene according to the present invention is excellent not only in tensile strength but also in tensile modulus, and the tensile modulus is desirably 20 GPa or more, preferably 40 GPa or more.

The degree of molecular orientation in the high molecular weight polyethylene molecular orientation molded article as described above, the X-ray diffraction method, birefringence method,
It can be known by the polarized fluorescence method. The molecular orientation molded product according to the present invention is, for example, the orientation degree according to the half-value width described in detail in Yukichi Kure and Teruichiro Kubo, Journal of Chemical Engineering, Vol. 39, p. (Here, H is the half width (゜) of the intensity distribution curve along the Debye ring of the strongest paratope plane on the equator line.) The molecule is selected so that the orientation degree F is 0.98 or more, particularly 0.99 or more. Desirably, they are oriented.

Next, a method for producing the oriented molecular product of high molecular weight polyethylene according to the present invention will be described.

In the present invention, in order to mold the molecular orientation molded article,
The high molecular weight polyethylene as described above and a diluent are mixed and kneaded.

As such a diluent, a solvent for high-molecular-weight polyethylene or various wax-like substances having dispersibility in high-molecular-weight polyethylene is used.

As the solvent, a solvent having a boiling point equal to or higher than the melting point of high molecular weight polyethylene, and more preferably equal to or higher than the melting point + 20 ° C is used.

As such a solvent, specifically, n-nonane,
n-decane, n-undecane, n-dodecane, n-tetradecane, n-octadecane or liquid paraffin,
Aliphatic hydrocarbon solvents such as kerosene, xylene, naphthalene, tetralin, butylbenzene, p-cymene, cyclohexylbenzene, diethylbenzene, benchylbenzene, dodecylbenzene, bicyclohexyl, decalin,
Aromatic hydrocarbon solvents such as methylnaphthalene and ethylnaphthalene or hydrogenated derivatives thereof, 1,1,2,2-tetrachloroethane, pentachloroethane, hexachloroethane, 1,2,3-trichloropropane, dichlorobenzene,
Halogenated hydrocarbon solvents such as 1,2,4-trichlorobenzene and bromobenzene, and mineral oils such as paraffin-based process oils, naphthene-based process oils, and aromatic-based process oils are used.

As the wax-like substance, a liquid substance at room temperature can be used, but a substance having a melting point of 25 ° C. or more is preferably used. By using such a solid wax at room temperature as a diluent, the wax begins to solidify immediately after being extruded from the die nozzle, and the orientation state of the high molecular weight polyethylene oriented in the die is not easily collapsed. Therefore, the molecular orientation tends to remain as a history in the obtained polyethylene molded body, so that a polyethylene molded body having a good degree of orientation can be obtained.

As such waxes, aliphatic hydrocarbon compounds or derivatives thereof are used.

As the aliphatic hydrocarbon compound, mainly a saturated aliphatic hydrocarbon compound, usually has a molecular weight of 2000 or less, preferably
1000 or less, more preferably 800 or less paraffinic wax is used. Specific examples of these aliphatic hydrocarbon compounds include n-alkanes having 22 or more carbon atoms, such as docosane, tricosan, tetracosane, and triacontan, or mixtures with lower n-alkanes containing these as main components, and separation and purification from petroleum. -Low-pressure polyethylene wax, high-pressure polyethylene wax, ethylene-copolymerized wax or medium-low pressure polyethylene, which is a so-called paraffin wax, a low-molecular-weight polymer obtained by copolymerizing ethylene or ethylene and another α-olefin. Waxes obtained by reducing the molecular weight of polyethylene such as high-pressure polyethylene by thermal degradation and the like, and oxide waxes of these waxes or oxidized waxes modified with maleic acid,
A maleic acid-modified wax or the like is used.

As the aliphatic hydrocarbon compound derivative, for example, one or more, preferably one to two, terminal or internal terminal of an aliphatic hydrocarbon group (alkyl group or alkenyl group)
, More preferably one compound having a functional group such as a carboxyl group, a hydroxyl group, a carbamoyl group, an ester group, a mercapto group, a carbonyl group, etc., having 8 or more carbon atoms, preferably 12 to 50 carbon atoms or 130 to 2000 molecular weight. Preferably, 200 to 800 fatty acids, aliphatic alcohols, fatty acid amides, fatty acid esters, aliphatic mercaptans, aliphatic aldehydes, aliphatic ketones and the like are used.

Specifically, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, etc. are used as fatty acids, and lauryl alcohol, myristyl alcohol, cetyl alcohol, stearyl alcohol, etc. are used as aliphatic alcohols. Examples of the aliphatic amide include caprinamide, laurinamide, palmitamide, and stearylamide, and examples of the fatty acid ester include stearyl acetate.

The mixing ratio (weight ratio) of polyethylene and diluent varies depending on these types, but generally, it is 3:97.
8080: 20, preferably 15: 85-60: 40. When the amount of the diluent is lower than the above range, the melt viscosity becomes too high, so that melt-kneading and melt-molding become difficult, and the surface of the molded product is extremely rough, and there is a tendency that stretch breakage and the like tend to occur. On the other hand, if the amount of the diluent is more than the above range, it becomes difficult to melt and knead, and the molded article tends to be poor in stretchability.

Melt kneading as described above is generally performed at a temperature of 150 to 300 ° C., preferably 170 to 270 ° C. At a temperature lower than the above range, the melt viscosity is too high and the melt molding tends to be difficult. When the temperature is higher than the above range, the molecular weight of the ultrahigh molecular weight polyethylene polymer decreases due to thermal degradation, and it tends to be difficult to obtain a molded article having a high elastic modulus and a high strength. The melt-kneading as described above may be performed by dry blending using a Henschel mixer, a V-type blender, or the like, or may be performed using a single-screw or multi-screw extruder.

By extruding the above-mentioned kneaded product of high-molecular-weight polyethylene and a diluent from a spinneret, an undrawn high-molecular-weight polyethylene molded article is obtained. At this time, in order to obtain a molded article having excellent strength, the shearing stress of the high-molecular-weight polyethylene during spinning is adjusted to 1.0 × 10 ⁵ dyn / cm ² to 8 × 10 ⁵ dyn / cm ^2.
Preferably, it is 2 × 10 ⁵ dyn / cm ² to 8 × 10 ⁵ dyn / cm ² . The spun melt can also be drafted, that is, stretched in the molten state. The ratio of the extrusion speed V ₀ of the molten resin in the die orifice to the winding speed V of the unstretched material that has been cooled and solidified can be defined as a draft ratio by the following formula.

Draft ratio = V / V ₀ such draft ratio depends like the molecular weight of the temperature and the polyethylene of the mixture, usually 3 or more, it is desirable that preferably 6 or more.

Also, the kneaded product of the high-molecular-weight polyethylene and the diluent is not limited to extrusion molding, and in the case of manufacturing various stretch-molded containers, it is possible to produce a preform for stretch blow molding by injection molding. is there. Cooling and solidification of the obtained molded product can be performed by forced cooling means such as air cooling or water cooling.

Next, when the thus-obtained unstretched molded product of high-molecular-weight polyethylene is subjected to stretching treatment, a high-molecular-weight polyethylene molecularly oriented molded product is obtained.

It is desirable that the stretching of the polyethylene molded body is generally performed at a temperature of 40 to 160 ° C, particularly 80 to 145 ° C. As a heat medium for heating and maintaining the unstretched molded body at the above-mentioned temperature, any of air, water vapor, and a liquid medium can be used. However, as a heat medium, a solvent capable of eluting and removing the diluent described above, and having a boiling point higher than the melting point of the molded article composition, specifically, decalin,
It is preferable to perform a stretching operation using decane, kerosene, or the like, because the diluent described above can be removed, and uneven stretching during stretching and a high stretching ratio can be achieved.

Of course, the means for removing the diluent from the polyethylene is not limited to the above-described method, but a method in which the unstretched material is stretched after treatment with a solvent such as hexane, heptane, hot ethanol, chloroform, benzene, etc. It can also be performed by a method of treating with a solvent such as ethanol, chloroform or benzene. In this way, a high molecular weight polyethylene molecular oriented molded article having a high elastic modulus and a high strength can be obtained.

The stretching operation can be performed in one stage or in two or more stages. Although the stretching ratio depends on the desired molecular orientation and the effect of improving the melting temperature accompanying the stretching ratio, the stretching operation is generally performed at a stretching ratio of 5 to 100 times, preferably 10 to 80 times. Is desirable.

In general, it is advantageous to perform stretching in two or more stages, and in the first stage, the stretching operation is performed while extracting the diluent in the extruded product at a relatively low temperature of 80 to 120 ° C. After that, it is preferable to continue the stretching operation of the molded body at a temperature of 120 to 160 ° C. and higher than the first-stage stretching temperature.

When the polyethylene molded article is stretched in this manner, the degree of orientation is 0.95 or more, preferably 0.96 or more, more preferably 0.98 or more, and particularly preferably 0.99 or more, and the high molecular weight polyethylene satisfying the relationship represented by the above formula [I]. A molecularly oriented molded article is obtained.

The thus-obtained oriented molecular product of high-molecular-weight polyethylene can be subjected to a heat treatment under constrained conditions, if desired. This heat treatment is generally performed at 140 to 180 ° C, particularly 150 to 175 ° C.
At a temperature of 1 to 20 minutes, especially 3 to 10 minutes. By the heat treatment, the crystallization of the oriented crystal part further proceeds,
Higher temperatures of the crystal melting temperature, improved strength and modulus, and improved creep resistance at elevated temperatures are provided.

Effects of the Invention The polyethylene oriented molded article according to the present invention is excellent in the moldability of the raw material high molecular weight polyethylene during its production, and is excellent in mechanical properties and can be made thin. Utilizing this property, the molecularly oriented molded article according to the present invention is a high-strength multifilament, string, rope, woven fabric,
In addition to industrial textile materials such as nonwoven fabrics, they are useful as packaging materials such as packing tapes.

In addition, the filament-shaped high molecular weight polyethylene molecular orientation molded article can also be used as a reinforcing fiber for various resins such as epoxy resin and unsaturated polyester, synthetic rubber and the like. In addition, since this filament has high strength and low density, it is particularly effective because it can reduce the weight compared with conventional molded products using glass fiber, carbon fiber, boron fiber, aromatic polyamide fiber, aromatic polyimide fiber, etc. It is. Like composite materials using glass fibers, etc., UD
(Unit Directional) Laminated plate, SMC (Sheet Molding Com)
It can be used for molding processes such as pounds) and BMC (Bulk Molding Compound), and is expected to be used for various composite materials in the field of lightweight and high strength, such as automotive parts, structures of boats and yachts, and substrates for electronic circuits. .

Furthermore, when the high molecular weight polyethylene molecular oriented molded article according to the present invention is subjected to corona discharge treatment, the adhesiveness is greatly improved, but the tensile strength is hardly reduced.

Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited to these examples.

Example 1 An ethylene-propylene copolymer (ethylene content 99.9%) having a molecular weight of 5.5 × 10 ⁵ (intrinsic viscosity measured in decalin at 135 ° C. is 6.5 dl / g) and paraffin wax (melting point 69 ° C., molecular weight) 490) was melt-spun under the following conditions. First, 0.1 part by weight of 3,5-dimethyl-tert-butyl-4-hydroxytoluene was added as a process stabilizer to 100 parts by weight of a high-molecular-weight ethylene-propylene copolymer. Next, using a screw type extruder, the mixture was melt-kneaded at a set temperature of 190 ° C., and the melt was continuously passed through a spinning die having an orifice diameter of 2 mm attached to the extruder at a shear rate of 25 sec ⁻¹ and a shear stress of 2.8 × 10 Melt spinning was performed under the conditions of ⁵ dyn / cm ² and a die temperature of 180 ° C. The spun fiber was taken out at a draft ratio of 33 times with an air gap of 180 cm, cooled and solidified in air to obtain an undrawn fiber. The degree of orientation of this undrawn fiber was 0.90.

Further, the undrawn yarn thus obtained was drawn under the following conditions to obtain oriented fibers (samples 1 to 3). That is, the above-mentioned undrawn yarn was subjected to three-stage drawing using four codet rolls. At this time, the heat medium of the first stretching tank and the second stretching tank was n-decane, and the temperature was 110 ° C. and 1 respectively.
The temperature was 20 ° C., the heat medium of the third stretching tank was triethylene glycol, and the temperature was 143 ° C. The effective length of each tank was 50 cm. At the time of drawing, a fiber having a desired drawing ratio was obtained by changing the rotation speed of the fourth codet roll to 0.5 m / min. The number of rotations of the second and third codet rolls was appropriately selected within a range where stable stretching was possible. Most of the initially mixed paraffin wax was extracted in the first draw tank and the second draw tank. The stretching ratio was determined by calculation from the rotation speed ratio between the first codet roll and the fourth codet roll.

The modulus of elasticity, tensile strength and elongation at break of the resulting high molecular weight polyethylene fiber were measured by Orientec Tensilon RT.
It measured at room temperature (23 degreeC) using the M-100 type tensile tester. At this time, the sample length between the clamps is 100 mm, and the pulling speed is 1
It was 00 mm / min. The elastic modulus is an initial elastic modulus, which is obtained from a slope of a tangent of a stress-strain curve. The fiber cross-sectional area required for the calculation was calculated from the weight with the density set to 0.960 g / cc. The degree of orientation of the drawn fiber was determined.

 Table 1 shows the results.

Example 2 An ethylene-1-butene copolymer (ethylene content: 99.9%) having a molecular weight of 5.4 × 10 ⁵ (intrinsic viscosity measured in decalin at 135 ° C. of 6.1 dl / g) was described in Example 1. A 30:70 (weight ratio) mixture with paraffin wax was melt-spun as in Example 1. However, die temperature 170 ℃
Met. The degree of orientation of the obtained undrawn fiber was 0.91.

Further, the undrawn yarn was drawn in the same manner as in Example 1 to obtain a drawn fiber (samples 4 and 5).

 Table 2 shows the results.

Example 3 A 30:70 (weight ratio) of a high molecular weight polyethylene having a molecular weight of 4.7 × 10 ⁵ (intrinsic viscosity measured in decalin at 135 ° C. of 5.8 dl / g) and the paraffin wax described in Example 1 was used. The mixture was melt-spun in the same manner as in Example 1 to obtain an undrawn fiber. However, the draft at this time was 50 times. The degree of orientation of the obtained undrawn fiber was 0.90.

Further, it was drawn in the same manner as in Example 1 to obtain a drawn fiber (sample 6).

 Table 3 shows the results.

Comparative Example 1 A 30:70 (weight ratio) mixture of polyethylene having a molecular weight of 2.5 × 10 ⁵ (intrinsic viscosity measured in decalin at 135 ° C. of 3.7 dl / g) and the paraffin wax described in Example 1 was prepared. The melt spinning was performed in the same manner as in Example 1. The degree of orientation of the obtained undrawn fiber was 0.85.

Further, the undrawn yarn was drawn in the same manner as in Example 1 to obtain drawn fibers (samples 7 to 9).

 Table 4 shows the results.

Comparative Example 2 Polyethylene similar to that used in Example 2 and Example 1
A 30:70 (weight ratio) mixture with the paraffin wax described in 1) was melt-spun under the same conditions as in Example 1 except that a spinning die having an orifice diameter of 4 mm was used. At this time, the temperature of the spinning die was 170 ° C. The degree of orientation of the obtained undrawn fiber was 0.88.

Further, the undrawn yarn was drawn in the same manner as in Example 1 to obtain a drawn fiber (sample 10).

 Table 5 shows the results.

Comparative Example 3 An ethylene-propylene copolymer (ethylene content: 99.9%) having a molecular weight of 1.2 × 10 ⁶ (intrinsic viscosity measured in decalin at 135 ° C. of 11.2 dl / g) and the paraffin wax described in Example 1 Was melt-spun in the same manner as in Example 1 except that the die temperature was 190 ° C. At a die temperature of 190 ° C. or less, spinning was difficult because the viscosity of the kneaded material was too high.

Further, when the undrawn yarn was drawn in the same manner as in Example 1, the fiber (sample 11) was easily broken, and a regular drawing of 10 times or more was impossible.

Table 6 shows the relationship among the tensile strength S, the weight average molecular weight M, and the fiber D of the high molecular weight polyethylene fiber as described above.

In each of Examples and Comparative Examples, spinnability and stretchability when producing high molecular weight polyethylene fibers were evaluated.

 Table 6 shows the results.

In addition, each Example (Samples 1 to 6) and Comparative Example (Samples 7 to 6)
FIG. 1 shows the relationship between the fineness (denier) and the strength (GPa) of the high molecular weight polyethylene fiber obtained in 10). In FIG. 1, the numbers indicate sample numbers.

Example 4 An ethylene-propylene copolymer (ethylene content: 99.9%) having an intrinsic viscosity of 5.6 dl / g and a molecular weight of 4.5 × 10 ⁵ measured in decalin at 135 ° C. and paraffin wax (melting point: 69 ° C., A mixture having a molecular weight of 490) and a ratio of 30:70 (weight ratio) was melt-spun under the following conditions. First, 0.1 part by weight of 3,5-dimethyl-tert-butyl-4-hydroxytoluene as a process stabilizer was mixed with 100 parts by weight of the ethylene-propylene copolymer.

Next, using a screw type extruder, the mixture was melt-kneaded at a set temperature of 190 ° C., and the melt was continuously passed through a spinning die having an orifice diameter of 2 mm attached to the extruder, at a shear rate of 25 sec ⁻¹ and a shear stress of 2.6 ×. 10 ⁵ dyn / cm ² , die temperature 180
Melting was prevented under the condition of ° C. At this time, the spun fiber was taken out at a draft ratio of 33 times with an air gap of 180 cm, cooled and solidified in air to obtain an undrawn fiber. The degree of orientation F of the undrawn fiber was 0.9.

The undrawn fiber was drawn in the same manner as in Example 1 to obtain a fiber.

Table 7 shows the tensile properties of the obtained drawn fibers (samples 12 to 14).

Example 5 A molten mixture similar to that described in Example 4 was subjected to a shear rate of 41 sec ^-1 , a shear stress of 3.1 × 10 ⁵ dyn / cm ² and a die temperature of 170.
Spinning and stretching were performed in the same manner as in Example 4 except that the temperature was changed to ° C. The degree of orientation F of the undrawn fiber was 0.93.

Table 8 shows the tensile properties of the obtained drawn fibers (samples 15 to 19).

Example 6 An ethylene-1-butene copolymer having an intrinsic viscosity of 5.7 dl / g measured in decalin at 135 ° C. and a molecular weight of 4.6 × 10 ⁵ (ethylene content: 99.8%) was used in Example 4. A 30:70 (weight ratio) mixture with the paraffin wax was melt-spun in the same manner as in Example 4. However, at this time, the shear rate was 33 sec ⁻¹ , the shear stress was 2.9 × 10 ⁵ dyn / cm ² , and the die temperature was 170 ° C. The degree of orientation F of the undrawn fiber is 0.9.
Was one. Further, the undrawn fiber was drawn by the method described in Example 4 to obtain a drawn fiber.

Table 9 shows the tensile properties of the obtained drawn fibers (samples 18 to 19).

Table 10 shows the relationship among the tensile strength S, the weight average molecular weight M, and the fineness D of the above high molecular weight polyethylene fibers.

In each of Examples and Comparative Examples, spinnability and stretchability when producing high molecular weight polyethylene fibers were evaluated.

 Table 10 shows the results.

FIG. 1 shows the relationship between the fineness (denier) and the strength (GPa) of the high molecular weight polyethylene fibers obtained in each of the examples (samples 12 to 19). In FIG. 1, the numbers indicate sample numbers.

Example 7 Sample-3 manufactured in Example 1 was subjected to corona discharge treatment manufactured by Tomoe Kogyo Co., Ltd. to set the distance between the bar-shaped electrodes to 1.0 mm, and the irradiation amount was 75 W.
The corona discharge treatment was performed once at / m ² · min. The tensile strength of the fiber after the treatment was 3.16 GPa (95% retention).

Comparative Example 4 Polyethylene having a molecular weight of 2.2 × 10 ⁶ (17.0 dl / g in intrinsic viscosity measured in decalin at 135 ° C.) and decalin 5:
A 95 (weight ratio) mixture was spun under the following conditions.

First, 0.1 part by weight of 3,5-dimethyl-tert-butyl-4-hydroxytoluene was blended as a process stabilizer with respect to 100 parts by weight of the mixture, and charged into a nitrogen-sealed separable flask, and heated at 180 ° C. Stir for 1 hour to form a homogeneous solution.

Next, the solution was put into a spinning cylinder, and was heated to 180 ° C under a nitrogen atmosphere.
At room temperature for 2 hours to defoam the solution. The solution was extruded from a spinning die having a diameter of 2 mm into a coagulation tank (water bath) located 30 cm below without applying a draft twice or more to obtain a gel-like filament. 1m /
After winding on a bobbin at a speed of minutes, the bobbin was immersed in an n-hexane bath at room temperature to replace decalin, which is a liquid component of the gel filament, with n-hexane. Furthermore, it was taken out of the n-hexane tank and sufficiently dried under a vacuum of 50 ° C.

Subsequently, dry fiber is placed in a nitrogen sealed heat tube at 50 cm / min.
And three-stage stretching was performed using four codet rolls. The effective length of each of the heat tubes was 50 cm. At this time, the temperature in the first heat tube was 110 ° C., the temperature in the second heat tube was 130 ° C., and the temperature in the third heat tube was 140 ° C. The stretching ratio is determined by the rotation ratio of the first codet roll and the fourth codet roll.
It was 60 times. The rotation speeds of the second and third codet rolls were appropriately selected within a range where stable operation was possible. Physical properties of the obtained polyethylene fiber were an intrinsic viscosity of 14.0 dl / g, a fiber of 21 denier, and a tensile strength of 2.85 GPa.

The polyethylene fiber was subjected to a corona discharge treatment under the same conditions as in Example 3. The tensile strength of the treated fiber is 1.75
GPa (retention: 61%).

Example 8 Ethylene-4-methyl-1- having a molecular weight of 6.0 × 10 ⁵ (intrinsic viscosity measured in decalin at 135 ° C. of 6.9 dl / g)
Example 1 with pentene copolymer (ethylene content 99.9%)
A 35:65 (weight ratio) mixture with the same paraffin wax as used in Example ¹ was applied at a shear rate of 33 sec ^-1 and a shear stress of 5.2 × 10 ⁵ d
An undrawn fiber was obtained in the same manner as in Example 1 except that yn / cm ² , the die temperature was 170 ° C, and the draft ratio was 60 times. The degree of orientation of the obtained undrawn fiber was 0.94.

Further, the obtained undrawn fiber was drawn in the same manner as in Example 1 to obtain a drawn fiber (samples 20 to 22).

 Table 11 shows the results.

Example 9 An ethylene-butene-1 copolymer (ethylene content: 99.9%) having a molecular weight of 5.0 × 10 ⁵ (intrinsic viscosity measured in decalin at 135 ° C. of 6.0 dl / g) was used in Example 1. An undrawn fiber was obtained in the same manner as in Example 1 except that a 40:60 (weight ratio) mixture with the same paraffin wax was used, except that the die temperature was 170 ° C. and the draft ratio was 60 times. The degree of orientation of the obtained undrawn fiber was 0.91.

Further, the obtained undrawn fiber was drawn in the same manner as in Example 1 to obtain a drawn fiber (samples 23 to 25).

 Table 12 shows the results.

Comparative Example 5 50:50 (weight ratio) of an ethylene polymer having a molecular weight of 1.7 × 10 ⁵ (intrinsic viscosity measured in decalin at 135 ° C. of 2.8 dl / g) and a paraffin wax similar to that used in Example 1 ) At a shear rate of 25 sec ^-1 and a shear stress of 1.9 × 10 ⁵ d
An undrawn fiber was obtained in the same manner as in Example 1 except that yn / cm ² was used. The degree of orientation of the obtained undrawn fiber was 0.85.

Further, the obtained undrawn fiber was drawn in the same manner as in Example 1 to obtain a drawn fiber (samples 26 to 28).

 Table 13 shows the results.

Table 15 shows the relationship between the tensile strength S, the weight average molecular weight M, and the fineness D of the high molecular weight polyethylene fibers as described above.

FIG. 1 shows the relationship between the fineness (denier) and the strength (GPa) of the high molecular weight polyethylene fibers obtained in each of the examples (samples 20 to 30). In FIG. 1, the numbers indicate sample numbers.

Comparative Example 6 20:80 (weight ratio) of an ethylene polymer having a molecular weight of 4.5 × 10 ⁵ (intrinsic viscosity measured in decalin at 135 ° C. of 4.5 dl / g) and a paraffin wax similar to that used in Example 4 ) Mixture at a shear rate of 10 sec ^-1 and a shear stress of 1.5 × 10 ⁵ d
An undrawn fiber was obtained in the same manner as in Example 1 except that yn / cm ² was used. The degree of orientation of the obtained undrawn fiber was 0.88.

Further, the obtained undrawn fiber was drawn in the same manner as in Example 1 to obtain a drawn fiber (samples 29 to 30).

 Table 14 shows the results.

[Brief description of the drawings]

FIG. 1 is a diagram showing the relationship between fineness and strength in high molecular weight polyethylene fibers obtained in Examples (Samples 1 to 6, Samples 12 to 25) and Comparative Examples (Samples 7 to 10, 26 to 30). is there.

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Claims (1)

(57) [Claims] Claims: 1. A molecularly oriented molded article of high molecular weight polyethylene having a weight average molecular weight of 300,000 to 600,000, having a fineness of 15 denier or less, a tensile strength of at least 2.0 GPa, and a tensile strength of at least 2.0 GPa. S (GP
a) and its weight average molecular weight M (g / mol) and its fineness D
(Denier) has the formula [I] Characterized in that the relationship satisfies the following relationship: