JPS60190330A - Manufacture of superhigh molecular weight polyethylene stretched product - Google Patents

Abstract

PURPOSE:To obtain a superhigh molecular weight polyethylene stretched product having a high elasticity modulus and a high tensile strength by a method in which a blend of a superhigh molecular weight polyethylene of a specific intrinsic viscosity and a paraffinic wax of a low molecular weight is molted, extruded and stretched under specific temperature condition. CONSTITUTION:A blend of 15-80pts.wt. a superhigh molecular weight polyethylene of an intrinsic viscosity of at least 5dl/g or more A and 85-20pts.wt. a paraffinic wax of a molecular weight of 2,000 or less B having a melting point of 40-120 deg.C is melted and mixed at 190-280 deg.C in a screw extruder. The mixture is extruded from a die kept at the melting point -210 deg.C and stretched at a draw ratio more than at least 3 times to obtain an aimed stretched product.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for melt extrusion drawing of ultra-high molecular weight polyethylene. More specifically, the present invention relates to a method for producing a stretched ultra-high molecular weight polyethylene having high tensile strength and elastic modulus by melt-extruding and stretching a composition comprising ultra-high molecular weight polyethylene and a specific paraffin wax.

Ultra-high molecular weight polyethylene has superior impact resistance, abrasion resistance, chemical resistance, tensile strength, etc. compared to general-purpose polyethylene, and its use as an engineering plastic is expanding. However, compared to general-purpose polyethylene, the melt viscosity is extremely high and the fluidity is poor, so it is very difficult to mold by extrusion molding or injection molding.Most of the polyethylene is molded by compression molding, and some rods etc. Currently, extrusion molding is performed at low speed.

On the other hand, as a method for drawing high-density polyethylene monofilaments at a high magnification, additives with a high boiling point higher than the melting point of polyethylene are added at 20 to 150% by weight based on the weight of polyethylene.
%, a primary fibrous material is formed from the obtained high concentration dispersion, and then the 5
A method of hot stretching to 3 to 15 times the original length while leaving an amount equivalent to ~25% of the additive (Japanese Patent Publication No. 37-9765), or spinning a solution of linear polyethylene with a molecular weight of 400,000 or more. A method of stretching at a temperature of at least 20 GPa has been proposed. However, these methods specifically use 0-dichlorobenzene,
This is a method in which the fibers are dispersed or dissolved in a solvent such as xylene or decalin and then spun using a specific method.This method involves continuous extrusion spinning using a screw extruder, and the drawing of ultra-high molecular weight polyethylene with a high molecular weight using such a liquid solvent. Even if you try to use it as a property improver, the difference in viscosity between the solvent and powder is so large that the solvent and powder cannot be mixed at all, and the solvent acts as a lubricant between the powder and the screw, causing the powder and screw to stick together. Co-rotation occurs and extrusion is almost impossible. Further, even if it could be extruded, it would be completely impossible to draw it because it was not mixed uniformly, and it was currently impossible to perform continuous melt extrusion spinning using a screw extruder. Furthermore, since these solvents have low boiling points and are highly flammable, they are dangerous to use in screw extruders heated by electric heat, and special care must be taken when using them.

On the other hand, in order to improve the moldability of ultra-high molecular weight polyethylene, 10 to 60 parts by weight of low-molecular-weight polyethylene with a molecular weight of 5.000 to 20,000 is added to 100 parts by weight of ultra-high molecular weight polyethylene. Kaisho 57-17
However, in these compositions, the molecular weight of the low molecular weight polyethylene added is too large, making it impossible to draw the melt extrusion spun monofilament to a high magnification of 20 times or more, resulting in a high elastic modulus. , it is not possible to obtain monofilaments with high tensile strength.

From this point of view, the present inventors conducted various studies aimed at developing a continuous extrusion molding method for drawn products of ultra-high molecular weight polyethylene having high elastic modulus and high tensile strength using a screw extruder, and as a result, they identified ultra-high molecular weight polyethylene. The object of the present invention can be achieved by using a composition containing paraffin wax, which was previously disclosed in Japanese Patent Application No. 57-2274
．． 47 and Japanese Patent Application No. 58-59976.

After further investigation, we found that even if the temperature of the die of the screw extruder was lower than 210℃, by increasing the residence time in the die of the screw extruder, that is, by lowering the extrusion speed of the molten resin, it was possible to achieve ultrahigh It has been found that molecular weight polyethylene and paraffin wax can be stably and continuously extruded using a screw extruder, and the present invention has been completed.

In other words, the present invention has a low intrinsic viscosity [η] of 5 dl.
A mixture of 15 to 80 parts by weight of ultra-high molecular weight polyethylene (A) having a molecular weight of 40 to 120°C and 85 to 20 parts by weight of a paraffin wax (B) having a melting point of 40 to 120°C and a molecular weight of 2,000 or less. Tensile strength characterized by melt-kneading in a screw extruder at a temperature of 280° C. to 280° C., extruding the unstretched material through a die at a temperature higher than the melting point of the mixture and lower than 210° C., and then stretching at a stretching ratio of at least 3 times, This paper proposes a method for producing stretched ultra-high molecular weight polyethylene that has both high elastic modulus.

The ultra-high molecular weight polyethylene (A) used in the method of the present invention has an intrinsic viscosity [η] of 5 at 135°C in decalin solvent.
dl/g or more, preferably in the range of F to 30 di/g. If [η] is less than 5 dl1g, a stretched product with excellent tensile strength cannot be obtained even if stretched. Also [η
] is not particularly limited, but if it exceeds 3041/g, the melt viscosity is high even if the paraffin wax (B) described below is added, and the melt spinnability with a screw extruder in the temperature range described below is poor.

The paraffin wax (B) used in the method of the present invention has a melting point of 40 to 120°C, preferably 45 to 1
at 10°C and a molecular weight of 2,000 or less, preferably i
, ooo or less, particularly preferably 800 or less. Ultra-high molecular weight polyethylene (A
) and the screw rotate together, making uniform melt spinning impossible. On the other hand, the melting point exceeds 120℃ and the molecular weight is 2
,000, if a draft is applied before cooling and solidifying, drawing breaks will occur, making it impossible to obtain a drawn product with high elastic modulus and high tensile strength, and as described below, excessive paraffin wax can be extracted from the drawn product. I can't even do that. In addition, when using a material with a molecular weight of 800 or less, by applying a draft before cooling and solidifying, a drawn product with a sufficiently high elastic modulus can be obtained even at a drawing ratio of more than 3 times.
,000, it is preferable to apply a draft and stretch at a stretching ratio of 5 times, preferably 10 times or more, before cooling and solidifying.

The melting point in the present invention is a value measured using a differential scanning calorimeter (DSC) according to ASTM D 3417.

Moreover, the molecular weight is a weight average molecular weight (Mw) measured by GPC method (gel permeation chromatography) under the following conditions.

Equipment: Waters Co., Ltd. 150C type column: Toyo Soda Co., Ltd. TSK GMH-6 (6mmφX 600
mm) Solvent: Orthodichlorobenzene (○DCB) Temperature:
135℃ Flow rate: 1. Om e /min Injection concentration: 30mg/20ml1!0DCB (Injection volume 400μl) In addition, manufactured by Toyo Soda Co., Ltd. and Pressure Chemical Co., Ltd.
Column elution volumes were calibrated by the universal method using standard polyethylene.

The paraffin wax (B) used in the method of the present invention is not particularly limited to a compound consisting only of carbon and hydrogen, as long as it has a melting point and molecular weight within the above range, and may contain a small amount of oxygen or other elements. You can stay there.

The paraffinic wax (B) is mainly composed of saturated aliphatic hydrocarbon compounds, specifically, n-alkanes having 22 or more carbon atoms such as tocosan, tricosane, tetracosane, triacontane, etc., or n-alkanes mainly composed of these. mixture with lower n-alkanes, so-called paraffin wax separated and purified from petroleum, medium/low pressure polyethylene wax which is a low molecular weight polymer obtained by copolymerizing ethylene or ethylene with other α-olefins, High-pressure polyethylene wax, ethylene copolymer wax, medium/low-pressure polyethylene, high-pressure polyethylene, and other waxes whose molecular weight has been lowered by thermal degradation, and oxidized waxes such as Fuchs oxides or maleic acid modified products. , maleic acid-modified wax, and the like.

Other hydrocarbon compounds that fall within the melting point and molecular weight range of the paraffinic wax (B) used in the present invention include aromatic hydrocarbon compounds such as naphthalene and dimethylnaphthalene, but unlike paraffinic waxes, these It has poor compatibility with high molecular weight polyethylene (A), and when used in the method of the present invention, it has poor compatibility with ultra high molecular weight polyethylene (A).
), and it is difficult to achieve uniform stretching or a high stretching ratio.

A specific example of a method for examining the compatibility between ultra-high molecular weight polyethylene (A) and paraffin wax (B) is a method of observing the cross section of an undrawn yarn using a high-magnification scanning electron microscope. That is, ultra-high molecular weight polyethylene (A
) and paraffin wax (B) in equal amounts are melt-kneaded and then melt-spun. Next, the obtained undrawn yarn is cut perpendicularly to its longitudinal direction with a sharp blade such as a microtome. A cross section cut out by the same process as the cross section was further immersed in a non-polar solvent such as hexane or hebutane at room temperature for at least 1 hour to extract and remove paraffin wax (B), etc. Comparative observation is made using a scanning electron microscope at a magnification of 1,000 times or more. Since the paraffin wax (B) of the present invention has good compatibility with ultra-high molecular weight polyethylene (A), depressions of 0.1 μ or more are hardly observed, and it can be used instead of paraffin wax (B). When naphthalene is used, poor dispersion occurs and numerous depressions of 0.1 μm or more are observed.

The method of the present invention includes the ultra-high molecular weight polyethylene (A):t
5 to 80 parts by weight, preferably 30 to 50 parts by weight, and the paraffin wax (B): 85 to 20 parts by weight.
parts by weight, preferably 70 to 50 parts by weight, at 190 to 280°C, preferably 190 to 250°C.
The melting point of the mixture is melted and kneaded in a screw extruder at a temperature of 210°C, preferably the melting point of the mixture is +210°C.
Extruding the unstretched material through a Gui at a temperature of 10°C or higher and lower than 210°C,
The film is then stretched at a stretching ratio of at least 3 times, preferably 5 times or more.

If the amount of ultra-high molecular weight polyethylene (A) is less than 15 parts by weight, it will be difficult to melt and knead it in a screw extruder, and the extruded product will have poor drawability, causing breakage and making it difficult to draw at high magnification or draft. Can not. On the other hand 8
If the amount exceeds 0 parts by weight, the melt viscosity becomes high, making melt extrusion difficult, and the extruded unstretched product (strand) has a rough surface and is likely to break during stretching.

When the temperature of the goo is below the melting point of the mixture, the melt viscosity is high and melt extrusion is difficult. The ultra-high molecular weight polyethylene (A) and the paraffin wax (B) can be mixed using a Henschel mixer, ■-blender, etc., or after mixing, the mixture can be further melt-kneaded using a single-screw or multi-screw extruder for granulation. This can be done by

When an undrawn material is extruded from a gooey, by applying at least one draft, preferably more than two drafts, before the molten material is cooled and solidified, it has a higher modulus of elasticity and a higher tensile strength than a drawn material that is not drafted. A stretched product with 1 strength can be obtained.

The term "draft" in the present invention refers to the drawing of the melt extruded from the screw extruder during melting, and refers to the drawing down of the melt. That is, the extrusion speed υ of the molten resin within the Gui orifice. The ratio of the winding speed υ of the cooled and solidified fiber to the draft ratio was defined as the following equation.

Draft ratio −υ/υ0 Further, the cooling may be performed by either air cooling or water cooling.

The temperature during stretching is usually 60℃ to the melting point of the mixture + 20℃
If the temperature is lower than 60°C, high-stretching may not be achieved.On the other hand, if the temperature exceeds the melting point of the mixture +20°C, the ultra-high molecular weight polyethylene (A) will be softened and stretched, but the There is a possibility that a stretched product with a good elastic modulus cannot be obtained.

A stretched product with a high elastic modulus can be obtained by using air, water vapor, or a solvent as a heating medium during the above-mentioned stretching process. However, as a heating medium, a solvent that can elute or ooze out the paraffin wax (B) is used. A substance with a boiling point of 2 or higher than the melting point of the mixture, specifically, for example, decalin,
It is preferable to use decane or kerosene because it is possible to extract excess paraffinic wax (B) or remove boiled wax during stretching, reduce stretching unevenness during stretching, and achieve a high stretching ratio. In addition, methods for removing excess paraffin wax (B) from a stretched product of ultra-high molecular weight polyethylene (A) are not limited to the above-mentioned method, but include a method in which an unstretched product is treated with a solvent such as hexane or heptane, and then stretched. The paraffin wax (B) can also be extracted and removed by treating the product with a solvent such as hexane or heptane, and a stretched product with high elastic modulus and high strength can be obtained.

When extracting the paraffin wax (B) with the above solvent or solvent, the paraffin wax (B) in the stretched product
When the remaining amount of B) is 10% by weight or less, microporous fibers can be obtained, and both the elastic modulus and strength obtained from the method of calculating the true cross-sectional area by weight conversion can exceed the values of the stretched product before extraction. Very preferable.

When the stretching ratio in the solvent is less than 3 times, the degree of high tensile strength and high elastic modulus is small, and the stretched product is accompanied by uneven stretching, which often impairs the appearance. When drawing, the final drawing ratio is 3 times or more, preferably 5.
It is sufficient that the stretching is doubled or more, and may be one-stage stretching or multi-stage stretching of two or more stages. Furthermore, when no drafting is applied, high strength and high elastic modulus can be achieved by increasing the final stretching ratio to 10 times or more.

Further, the final stretching speed during stretching is not particularly limited, but from the viewpoint of productivity it is 3 m/min or more, preferably 5 m/min.
It is better to have n or more.

The ultra-high molecular weight polyethylene (A) used in the present invention contains additives that can be normally added to polyolefins, such as heat stabilizers, weather stabilizers, pigments, dyes, and inorganic fillers, within a range that does not impair the purpose of the present invention. It may be added in advance.

The drawn product of ultra-high molecular weight polyethylene obtained by the method of the present invention has high tensile strength and high elastic modulus that cannot be obtained with conventional drawn products of ordinary polyethylene. In addition to the field of drawn yarn, it can be used in the field of high elastic modulus, high strength 4 fibers, and can be used in various reinforcing materials that require lightness. Furthermore, it is suitable for functional materials such as selective membranes and electrets that utilize the highly aligned crystal arrangement achieved by ultra-high stretching and the micropores that are generated as a by-product by extracting excess paraffin wax (B). is also excellent.

Next, the present invention will be explained in more detail with reference to Examples.
The invention is not limited to these embodiments unless it goes beyond the gist of the invention.

Experimental example 1 Ultra high molecular weight polyethylene ([η) -8,20dl! /
g) and paraffin wax (melting point = 69°C, molecule i!=
460) was melt-spun and drawn under the following conditions. After mixing ultra-high molecular weight polyethylene powder and crushed paraffin wax, 20mm
Melt kneading was performed at a resin temperature of 200° C. using a screw extruder with φ, ■, /D=20. The melt was then extruded through a die with an orifice diameter of 4.0 mm and a goose temperature set at 170°C, and solidified in ice water at 0°C with an air gap of 1:5 cm. At this time, the extrusion speed of the molten resin was 6.0 cm/min, and the withdrawal was performed so that the winding speed was 0.3 m/min. That is, the draft ratio was set to 5. Subsequently, the film was stretched using two pairs of godet rolls in a stretching bath using n-decane as a heating medium (temperature inside the bath was 130° C., length of the bath was 40 cm).

During stretching, the rotational speed of the first godet roll is set to 0.
Fibers with different drawing ratios were obtained by appropriately changing the rotation speeds of the second godet roll and the third godet roll at 5 m/min. For stretching, the film was first stretched to a stretching ratio of 4.0 times using a second godet roll, and then a second stage of stretching was performed to a predetermined stretching ratio using a third godet roll. However, the stretching ratio was calculated from the rotation ratio of the godet roll. Table 1 shows the tensile modulus, tensile strength, and elongation at break at each stretching ratio. The tensile modulus, tensile strength, and elongation at break were measured at room temperature (23° C.) using an Instron universal testing machine model 1123 (manufactured by Instron). At this time, the sample length between the clamps was 100 mm, and the tensile speed was 10
0mm and 7 minutes. However, the tensile modulus was calculated using stress at 2% strain. The fiber cross-sectional area required for calculation is
The weight and length of the fibers were measured assuming that the density of polyethylene was 0.96 g/c4.

Table 1 Experimental Example 2 Ultra-high molecular weight polyethylene ((η) = 8.20 dI/g
) and paraffin wax (melting point -69℃, molecule 11=
460) was subjected to melt spinning and drawing under the same conditions as in Experimental Example 1. However, the molten material is extruded through a holder with an orifice diameter of 4111 In and a temperature of 170°C, and the air gap is set at 0°C with an air gap of 5Q.
It was solidified in ice water. At this time, the extrusion speed of the molten resin was 6.0 cm/min, and the winding speed was 0.6 m/min.
I made a withdrawal so that the amount would be /min.

That is, the draft ratio was set to 10. Stretching is carried out by pre-stretching to a stretching ratio of 3.0 times using a second Godet roll, and then
Stretching of each stage was carried out using a third godet roll to a predetermined stretching ratio. Table 2 shows the tensile modulus, tensile strength, and elongation at break at each stretching ratio. By increasing the draft ratio,
It can be seen that a drawn product having higher tensile strength than the drawn product in Table 1 can be obtained.

Table 2 8 Experimental Example 3 Ultra-high molecular weight polyethylene ((η) = 8.20 dl/g
) and paraffin wax (melting point -69℃, molecular weight -46
A 25:75 blend of 0) was melt-spun and drawn under the same conditions as in Experimental Example 1. However, if the orifice diameter is 4
The melt was extruded through a die with a die temperature of 170° C. and solidified in ice water at 0° C. with an air gap of 5 ctn. At this time, the extrusion speed of the molten resin was 6.0c.
m/min, and the withdrawal was performed so that the winding speed was 3.0 m/min.

That is, the draft ratio was set to 50. Stretching is carried out by pre-stretching to a stretching ratio of 3.0 times using a second Godet roll, and then
Stretching of each stage was carried out using a third godet roll to a predetermined stretching ratio. Table 3 shows the tensile modulus, tensile strength, and elongation at break at each stretching ratio. By increasing the draft ratio,
Table 3 Compared to the stretched product in Table 1 Experimental example 4 Ultra-high molecular weight polyethylene ([η) = 8.20 dl/g
) and paraffin wax (melting point = 69℃, molecular weight = 4
A 25:75 blend with 60) was subjected to melt-spinning and drawing under the same conditions as in Experimental Example 1. However, the molten material was extruded through a die with an orifice diameter of 41 and a temperature of 170° C., and was solidified in air at room temperature with an air gap of 2 Qcm. At this time, the extrusion speed of the molten resin was 6.0c.
m/min, and the withdrawal was performed so that the winding speed was 0.3 m/min.

That is, the draft ratio was set to 5. For stretching, the film was first stretched to a stretching ratio of 4.0 times using a second godet roll, and then a second stage of stretching was performed to a predetermined stretching ratio using a third godet roll. Table 4 shows the tensile modulus, tensile strength, and elongation at break at each stretching ratio. It can be seen that by increasing the draft ratio, a drawn product with high tensile strength can be obtained.

Table 4 Example 5 Ultra-high molecular weight polyethylene ([η) =8.20c11/
g) and paraffin wax (melting point = 69°C, molecular weight -4
A 25:75 blend with 60) was melt-spun and stretched under the same conditions as in Experimental Example 1 and 10. However, the molten material was extruded through a die with an orifice diameter of 4 nm and a temperature of 170° C., and solidified in air at room temperature with an air gap of 20 cm. At this time, the extrusion speed of the molten resin was 6.0 cm/min, and the winding speed was 0.8 m/min.
I made a withdrawal so that it would be min.

That is, the draft ratio was set to 10. Stretching is carried out by pre-stretching to a stretching ratio of 3.0 times using a second Godet roll, and then
Stretching of each stage was carried out using a third godet roll to a predetermined stretching ratio. Table 5 shows the tensile modulus, tensile strength, and elongation at break at each stretching ratio. By increasing the draft ratio,
Comparison with the drawn product in Table 4 Table 5 23 Experimental Example 6 Ultra-high molecular weight polyethylene ([η) = 8.20 dl/g
) and paraffin wax (melting point = 69℃, molecular weight = 4
A 25:75 blend with 60) was subjected to melt-spinning and drawing under the same conditions as in Experimental Example 1. However, the melt was extruded through a gouie with an orifice diameter of 4 mm and a gouie temperature set at 170° C., and solidified in air at room temperature with an air gap of 20 cI11. At this time, the extrusion speed of the molten resin was 6
．． Ocm/min, and the winding speed is 3.0m/m
I made a withdrawal so that it would become in.

That is, the draft ratio was set to 50. Stretching is carried out by pre-stretching to a stretching ratio of 3.0 times using a second Godet roll, and then
The stretching of each stage was repeated at a predetermined stretching ratio using a third godet roll. Table 6 shows the tensile modulus, tensile strength, and elongation at break at each stretching ratio. By increasing the draft ratio,
Compared to the stretched product in Table 4, Table 6] - [] Experimental Example 7 Ultra-high molecular weight polyethylene ([η) = 8.20d! /g
) and paraffin wax (melting point -69℃, molecular weight = 4
A 25 i 75 blend with 60) was subjected to melt spinning and drawing under the same conditions as in Experimental Example 1. However, the melt was extruded through a gouie with an orifice diameter of 4n+m and a die temperature set at 170°C, and solidified in ice water with an air gap of 5cIn°C. At this time, the melt phase extrusion speed was 6.0 c
m/min, winding speed 3.0cm/m
I made a withdrawal so that it would become in.

, the draft ratio was set to 0.5. For stretching, the film was first stretched to a stretching ratio of 3.0 times using a second godet roll, and then a second stage of stretching was performed using a third godet roll to a predetermined stretching ratio. Table 7 shows the tensile modulus, tensile strength, and elongation at break at each stretching ratio.

Table 7 Experimental example 8 Ultra high molecular weight polyethylene ([η) = 8.20 dl/g
) and paraffin wax (melting point -69℃, molecular weight -46
A 25:75 blend of 0) was melt-spun and drawn under the same conditions as in Experimental Example 1. However, if the orifice diameter is 4
The melt was extruded through a Dali C with m+n temperature set at 170° C., and solidified in air at room temperature with an air gap of 20 cm. At this time, the extrusion speed of the molten resin was (3.Qcm/min), and the withdrawal was performed so that the winding speed was 3.Qcm/min.

That is, the draft ratio was set to 0.5. For stretching, the film was first stretched to a stretching ratio of 3.0 times using a second godet roll, and then a second stage of stretching was performed to a predetermined stretching ratio using a third godet roll. Table 8 shows the tensile modulus, tensile strength, and elongation at break at each stretching ratio.

Table 8 Experimental Example 9 Ultra-high molecular weight polyethylene ([η] = 8.20 dl/g
) and paraffin wax (melting point -69℃, molecular weight -46
A 50:50 blend of T-0) with T-
After forming the Gui film, it was stretched. After mixing the ultra-high molecular weight polyethylene powder and the pulverized paraffin wax, the mixture was melt-mixed and pelletized using a screw extruder with a diameter of 20 mm and L/D=20 at a resin temperature of 220°C. Next, the pellet was heated to 180°C in a coat hanger type mold (
The film was formed using a 20 mmφ, L/D=20 screw extruder with a lip length of 300 mm and a lip thickness of 0.5 mm.The film width and thickness were adjusted using a roll cooled with 20°C cold water. 300111
m and adjusted to 0.51. Subsequently, the film was stretched using two pairs of snap rolls in a stretching tank (tank temperature: 130° C., tank length: 180 cm) using n-decane as a heating medium.

During stretching, the rotational speed of the first snap roll was set to 0.
5 m/min to a stretching ratio of 8.0 times with the second Snap roll, and then by appropriately changing the rotation speed of the third Snap roll, stretched tapes with different stretching ratios were obtained. However, the stretching ratio was calculated from the rotation ratio of the first and third snack rolls. Tensile modulus, tensile strength, and elongation at break of stretched tape at each stretching ratio 9 Table 9 30 Comparative Example 1 Ultra-high molecular weight polyethylene ([η) = 8.20 dl/g
) and paraffin wax (melting point -69℃, molecular weight = 4
A 25:75 blend with 60) was subjected to melt-spinning and drawing under the same conditions as in Experimental Example 1. However, it was extruded through a gouie with an orifice diameter of 4 mm and a gouie temperature set at 100°C, and solidified in ice water with an air gap of 5c+nT: 0°C. At this time, the extrusion speed of the molten resin was 6.0CIII
/lll1n, and the winding speed is 6.0CJn /
The strand was wound to a length of 11 inches. However, it was not possible to wind the strands continuously. Moreover, the obtained strands were brittle and could not withstand stretching even if continuous strands were obtained.

Comparative Example 2 Ultra-high molecular weight polyethylene ([η) = 8.20c11/
g) and paraffin wax (melting point -69°C, molecular weight -4
A 25:75 blend with 60) was subjected to melt-spinning and drawing under the same conditions as in Experimental Example 1. However, it was extruded through a gouie with a diameter of 4 mm and a gou temperature set at 100° C., and solidified in air at room temperature with an air gap of 20 cm. At this time, the extrusion rate of the molten resin is 6.
0cm/min, and the winding speed is 6.0cm/m.
The strand was wound so that it became in. However, it was not possible to wind the strands continuously. Moreover, the obtained strands were brittle and could not withstand stretching even if continuous strands were obtained.

Comparative example 3 Ultra high molecular weight polyethylene ((η) -8,20 dl/g
) and n-hexadecane were melt mixed under the same conditions as in Experimental Example 1.

However, the melt was extruded through a gouie with an orifice diameter of 2 mm. However, since the mixture co-rotates within the screw extruder, uniform molten strands could not be obtained, and uniform drawn fibers could not be obtained.

In the drawn fibers obtained in this experimental example, no residual paraffin wax was found in the DSC measurement according to ASTM D 3417.

In this experimental example, in order to examine the influence of draft, the tensile modulus and tensile strength according to different cooling conditions during the preparation of unstretched products are plotted against the stretching ratio in FIGS. 1 and 2.

Furthermore, the tensile strength was plotted against the tensile modulus in FIG. As is clear from the figure, no particular influence was observed by the cooling conditions during the preparation of the unstretched product.

The tensile modulus and tensile strength are influenced by draft and show a markedly different dependence on the draw ratio. It is clear from FIG. 3 that when a drawdown is applied during melting, a drawn product having a higher elastic modulus and higher strength can be obtained than when a drawdown is not applied. That is, high elastic modulus and high strength fibers can be obtained by applying a draft before cooling and solidifying3.

[Brief explanation of the drawing]

FIG. 1 shows the relationship between tensile modulus and stretching ratio, FIG. 2 shows the relationship between tensile strength and stretching ratio, and FIG. 3 shows the relationship between tensile strength and tensile modulus. Applicant Mitsui Petrochemical Industries Co., Ltd. Agent Kazu4 Yamaguchi (shicTO) suspected of kidnapping (shidO) lambda

Claims (1)

[Claims] (1) Ultra-high molecular weight polyethylene (A) having an intrinsic viscosity of at least 5 dl/g or more, 15 to 80 ffiHI5 and 85 to 20 parts by weight of paraffin wax (B) having a melting point of 40 to 120°C and a molecular weight of 2000 or less. The mixture is melt-kneaded in a screw extruder at a temperature of 190 to 280°C, the unstretched material is extruded through a goo having a temperature higher than the melting point of the mixture and lower than 210°C, and then stretched at a stretching ratio of at least 3 times. A method for producing a stretched ultra-high molecular weight polyethylene product.