JPS62104911A - Production of drawn yarn of ultra-high-molecular-weight polyethylene and production unit for undrawn yarn thereof - Google Patents

Abstract

PURPOSE:To make it possible to continuously produce undrawn yarn of ultra- high-molecular-weight polyethylene having >=1mm outer diameter, by using a molding machine having a die with large L/D attached to the tip of an extruder equipped with a slotted cylinder and a low compression screw. CONSTITUTION:An ultra-high-molecular-weight polyethylene having >=5dl/g intrinsic viscosity [eta] is fed to a molding machine having a tube die 7 which has a mandrel 5 rotates with revolution of screw and >=5 (preferably 30-70) L/D attached to the tip of an extruder equipped with a slotted cylinder 2 and a screw 3 having 1-2.5 compression ratio, melted by the screw, extruded from the tube die, cooled, divided in the direction of flow of the tube and drawn.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing a drawn ultra-high molecular weight polyethylene yarn having excellent tensile strength, and an apparatus for producing the raw yarn.

[Conventional technology]

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 a solution of linear polyethylene with a molecular weight of 400,000 or more. A method of spinning and drawing at a temperature of 20 GPa (Japanese Patent Application Laid-Open No. 1540-154
Publication No. 8) has been proposed. However, although these methods can obtain drawn yarns with high elasticity and high strength, they are made by diluting ultra-high molecular weight polyethylene with a large amount of solvent and have extremely low viscosity. It is extremely difficult to obtain yarn that can exceed this level. Therefore, the drawn yarn is usually 10 denier or less (diameter: 0.03B11φ or less), and the thickest is about 50 denier, so such thin denier yarn can be used for high-strength large ropes, nets, plastic wires that require insulation, etc. To use it, it is necessary to twist a large amount of drawn yarn, which is a complicated process, and the resulting lobes and nets are highly rigid.
Not only does it have insufficient flexibility, but it also has the disadvantage of easily becoming fluffy in appearance.

On the other hand, a method for producing an oriented polymer by elongating a polymer having a weight average molecular weight of 150,000 or more at a temperature of about 75 to 140°C and a deformation ratio of about 18 or more (Japanese Unexamined Patent Publication No. 52-197)
74682) has been proposed. However, the publication also states that "the diameter of the fiber or the thickness of the film or tape before stretching is preferably about 1 m1 or less," and the example also states that for polyethylene with a molecular weight of about 300,000, the diameter There is only an example described in which a thin filament (original thread) with a diameter of 0.7 or less is spun from a circular orifice of 1 orifice. And the molecular weight is s
For polyethylene of oo, ooo, gauge size 1clIX0,2C from compression molded 0,5n thick sheet
As is clear from the fact that there is only an example of drawing a dumbbell-shaped sample in No. 11 as a raw yarn, and there is no description of the method for manufacturing the yarn, the yarn is made from ultra-high molecular weight polyethylene with an extremely high molecular weight and has a diameter exceeding 50 denier. At present, the technology for industrially producing it has not yet been established.

[Problem that the invention seeks to solve]

In view of this situation, the present inventors conducted various studies to develop a method for continuously producing yarn made of ultra-high molecular weight polyethylene and having an outer diameter exceeding 1nφ, and as a result, they developed a method equipped with a grooved cylinder and a low compression screw. L/D at the tip of the extruder
By using a molding machine that connects 10 or more dies and is equipped with an annealing cylinder downstream of the die, and by specifying molding conditions, ultra-high molecular weight polyethylene yarn with an outer diameter exceeding 1 φ can be manufactured. Furthermore, by drawing the raw yarn under specific conditions, ultra-high molecular weight polyethylene with an outer diameter of 0.1 mm or more and a tensile strength of 10 kg/l or more can be obtained. It was discovered that a drawn yarn could be obtained, and an application was previously filed as Japanese Patent Application No. 13624/1983.

The present inventors further investigated to develop a method for producing drawn ultra-high molecular weight polyethylene yarn with excellent tensile strength, and as a result, they drew a raw yarn obtained by dividing an ultra-high molecular weight polyethylene tube produced by a specific method. By doing so, it was found that a drawn yarn having a denier of 50 denier or more and a tensile strength of 50 kg/am 2 or more could be obtained, and the present invention was achieved.

[Means for solving problems]

In other words, the limiting viscosity [η] of the present invention is 5d! /g or more of ultra-high molecular weight polyethylene is melted in a screw extruder, then extruded through a tube die with a mandrel rotating with the rotation of the screw and having an L/D of at least 5, cooled, and the resulting tube is A method for producing an ultra-high molecular weight polyethylene drawing system characterized by dividing and then drawing, and from the extruder side, a grooved cylinder and a compression ratio of 1.
an extruder consisting of a screw ranging from 2.5 to 2.5;
At least L/D consisting of a mandrel connected to the tip of the screw and rotating with the rotation of the screw and an outer die is 5, and a cross-sectional area S1 of the resin flow path at the inlet of the tube die and a cross-sectional area S2 of the resin flow path at the intermediate portion of the tube die. The ratio (31/32) is in the range of 0.5 to 3.0, and the ratio (32/33) of the cross-sectional area S2 of the resin flow path at the middle part of the tube die and the cross-sectional area S3 of the resin flow path at the outlet of the tube die is 1.0
The present invention provides an apparatus for producing raw yarn for drawn ultra-high molecular weight polyethylene yarn, characterized in that it is comprised of a tube die and a tube dividing device in the range of 3.0 to 3.0.

[For production]

The ultra-high molecular weight polyethylene used in the present invention has an intrinsic viscosity (η) of 5 d1/g as measured at 135°C in a decalin solvent.
Above, preferably 8 to 21/g and melt flow rate (MFR: ASTM D 1238.F')
Homopolymer of ethylene or ethylene with other α-olefins such as propylene, 1-butene, 1-hexene, 1-octene, 4-methyl-1-pentene, etc. It is mainly a copolymer and is crystalline.

Intrinsic viscosity [η] is 5d! If it is less than /g, the average molecular chain is short and a drawn yarn with high tensile strength cannot be obtained even if the drawing ratio is increased.

The method for producing the ultra-high molecular weight polyethylene drawn yarn of the present invention includes the method of manufacturing the ultra-high molecular weight polyethylene using a screw extruder,
A tube die with an L/D of at least 5, preferably 10 or more, more preferably 30 to 70, preferably melted in a screw extruder equipped with a grooved cylinder (barrel), and then the mandrel rotates with the rotation of the screw. This method is characterized by extruding the tube from a tube, cooling it, dividing the obtained tube in the machine direction (longitudinal direction), and then stretching it.

Unlike general-purpose polyethylene, the melt of ultra-high molecular weight polyethylene used in the present invention is a rubbery lump with poor fluidity. Therefore, in a tube die with an L/D of less than 5, the melt is Even if a tube obtained without completely uniform fusion is drawn, thread breakage occurs during sleep-stretching, and a drawn thread with sufficient strength cannot be obtained. On the other hand, the upper limit of L/D is not particularly limited, but is preferably 70 or less in practical terms. In addition, L/D of tube die is correlated with productivity, and L
The larger /D is, the higher the production speed can be.

Further, the mandrel of the tube die needs to be rotated as the screw of the extruder rotates.

The rotation speed of the mandrel does not necessarily have to be the same as the rotation speed of the screw, and the object of the present invention can be achieved as long as the mandrel rotates. If the mandrel does not rotate, the mandrel will be eccentric, making it impossible to obtain a tube of uniform thickness, resulting in a tube with poor stretchability. Methods for attaching a mandrel to the screw tip include fixing, screwing, fitting, or inserting the mandrel directly to the screw tip, and attaching with a joint, etc.; The method of disassembly is simple, and since it can only be removed, there are advantages such as easy disassembly and cleaning of the extruder and tube die, and easy change of the inner diameter size.

In the method of the present invention, the extrusion temperature of the ultra-high molecular weight polyethylene is not particularly limited as long as it is Takayama A temperature below the melting point of the resin and lower than the decomposition temperature of the resin.

The preferred extrusion temperature conditions for ultra-high molecular weight polyethylene are: extruder temperature of 200 to 330°C, temperature of tube die inlet to middle part of 180 to 310°C, and tube die middle part to outlet temperature. It is preferable to set the temperature to be in the range of 136 to 170°C because randmelt fracture does not occur in the tube die. The method for manufacturing the tube which is the raw material for the drawn yarn of the present invention is detailed in Japanese Patent Application No. 101712/1983.

After the tube extruded from the tube die is cooled, it is divided in the flow direction to form yarn, and the tube may be cooled by any cooling means such as air cooling or water cooling.

The tube may be divided continuously after cooling the tube extruded from the tube die, or it may be separately divided after being taken out as a tube. Further, the tube is divided by applying a blade to the tube, but such a blade may be a fixed type or a rotary type. Among these, a rotary type is preferable because it maintains its sharpness. Further, the tube can be divided into two, four or more parts as appropriate.

In order to obtain a drawn yarn with excellent tensile strength from a raw yarn made of divided tubes, it is necessary to draw the yarn by at least 5 times, preferably 10 times or more, and more preferably 14 times or more. The drawn yarn may be obtained by either dry drawing or wet drawing, but wet drawing is preferable in terms of heat transfer efficiency and temperature control accuracy.

Further, a multi-stage drawing method is preferable to a single-stage drawing method because it allows the drawing ratio to be increased and a drawn yarn with high strength and high elastic modulus can be obtained. The drawing temperature of the raw yarn is usually 95℃ to melting point +5℃
, preferably in the range of 130 to 145°C. If the drawing temperature is lower than 95° C., the drawing ratio may not be large and a high-strength drawn yarn may not be obtained. On the other hand, at a drawing temperature of 145° C. or higher, the raw yarn may melt and break easily (and the drawing properties may not be stable).

As shown in FIG. 1, the apparatus for producing drawn ultra-high molecular weight polyethylene Itokawa yarn of the present invention has a grooved cylinder 2 and a compression ratio of usually 1 to 2.5, preferably 1.3 to 1. An extruder 1 consisting of a screw 3 with a diameter in the range of 8, a mandrel 5 connected to the screw tip 4 and rotating with the rotation of the screw, and an outer die 6 with an L/D of at least 5, preferably 10, more preferably 30 to 30. 70, the ratio (Sl/S2) of the cross-sectional area Sz of the resin flow path in the tube die inlet portion 71 to the cross-sectional area S2 of the resin flow path in the tube die intermediate portion 72 is 0.5 to 3.0;
Preferably 1.0 to 2.0 and the ratio of S2 to the cross-sectional area S3 of the resin flow path of the tube die exit lower 3 (32/S
3) is 1.0 to 3.0, preferably 1.1 to 2
．． It consists of a tube diameter in the range of 0 and a tube splitting device 8.

The groove portion 21 of the grooved cylinder 2 allows the ultra-high molecular weight polyethylene powder to be stably supplied to the compression section 22.

Further, if the compression ratio of the screw 3 is less than 1.0, the compression stress of the resin against the cylinder wall surface is small and the extrusion amount becomes unstable, which tends to cause a surging phenomenon or poor degassing of the product, resulting in poor appearance of the product. On the other hand, if it exceeds 2.5, the resin temperature will abnormally rise due to clogging phenomenon and frictional heat in the compression part 22, and the molecular weight of the resin will decrease significantly due to thermal decomposition, resulting in problems such as loss of product physical properties such as friction coefficient and wear resistance. This is not preferable because it causes

The mandrel 5 is screwed onto the tip of the screw 3.

If the L/D of the tube die is less than 5, the molten resin will not be completely fused and a good flexible tube will not be obtained. In addition, the L/D of the tube die is the tube die inlet part 71.
This is the ratio of the length from the tube die exit lower 3 to the inner diameter of the outer die 6 of the tube die exit lower 3. Also Sl/
There is no particular problem if S2 is in the range of 0.5 to 3.0, but if the S2/S3 ratio is less than 1.0, the molten resin will not be completely fused, while if it exceeds 3.0, the resin pressure will decrease. This makes it difficult to extrude the tube.

As mentioned above, the flow path area of the tube die basically becomes narrower toward the tube die outlet.

That is, although it is a tapered die, the tube die tip 7
4 is preferably a so-called straight shape in which the flow path area does not change, since dimensional accuracy can be maintained to a high degree. In addition, the straight part usually has an L/D of 5 to 10.
That's about it.

It is preferable for the tip 51 of the mandrel 5 to protrude outside the outer die 6 because the meandering of the extruded molten resin is corrected.

The tube dividing device 8 is a device that divides the tube extruded from the tube dia in the flow direction (vertical direction) of the tube after cooling, and is composed of a blade 81 for dividing the tube and a support device 82 for the blade 81. The blade 81 is fixedly or rotatably attached to a support device 82. The tube dividing device 8 may be installed in the same series on the downstream side of the tube dia so that the tubes extruded from the tube dia and cooled can be continuously divided, or the tube 7 may be temporarily separated by a take-off machine (not shown). It may be installed in a separate series in order to be separately divided after being wound up through a . After the splitting, the yarn taken off is drawn using a known drawing device.

〔Effect of the invention〕

Since the raw yarn (undrawn yarn) used in the method of the present invention is a thin raw yarn obtained by dividing an ultra-high molecular weight polyethylene tube,
Despite the thick denier, compared to a circular undrawn yarn of the same denier, the inside of the raw yarn is heated evenly and rapidly during stretching, so the drawability (uniform drawability, high-magnification drawability) is improved. A large denier drawn ultra-high molecular weight polyethylene yarn with excellent tensile strength is obtained. Furthermore, such drawn yarns have the inherent characteristics of ultra-high molecular weight polyethylene, such as abrasion resistance, self-lubricating properties, impact resistance, and water resistance, and are lightweight, so their uses were limited for conventional ultra-high molecular weight polyethylene filaments. It can be suitably used for large ropes and ropes for mooring ships, plastic wires that require insulation, and the like.

Examples 1 to 5 Flexible tubes were manufactured using the manufacturing apparatus shown in FIG. 1 having the following specifications.

Screw outer diameter 30 φ, effective screw length L/
D) 32.7-Width pi' 7chi 20mm constant, screw compression ratio 1.8, tube die length 750mm, die exit outer die inner diameter 22m + iφ, guide exit outside mandrel n i't dragonφ, ultra high molecular weight polyethylene [η ): 15dl/g, M
Powder resin with FR: less than 0.01 g/10 m1n, melting point: 136°C, and bulk density: 0.45 g/cnl (product name: Hi-ZEX ■Million 240M, Mitsui Petrochemical Industries ■)
using an extruder, Goui base (D) and Goui end (D)
D2) 0) Set temperature to 280°C and 270'C respectively.
and 160°C, the screw rotation speed was set to 25 rpm, and a flexible tube made of ultra-high molecular weight polyethylene with an outer diameter of 6 mm and an inner diameter of 411 mm was obtained by taking it off at a speed of 2.5 m/min. Manufactured. Next, the tube was divided into eight pieces using the dividing device shown in FIG.
．． It was stretched 12, 14, 16, 18 times (133°C, 1 stage stretching).

The physical properties of each drawn yarn obtained were measured by the following method. The results are shown in Table 1.

Density: ＾STM D 1505 (without annealing)
Denier: Apply an initial load so that there is no slack in the drawn yarn, take 10 900 mm long yarns, and measure the weight of each yarn using a precision balance with a sensitivity of 0.1 mmg (Shima 8! Seisakusho). These average values are converted to the number of grams per 9000 m.

Tensile strength: Yonekura Instron type universal testing machine (CAT
Y-1001ZS') Tensile strength at break (kg/
2) and elongation (%) were determined.

Temperature: 23'C Examples 6 to 9 The split yarn was first stretched 8 times in a 133°C triethylene glycol liquid drawing tank, and then further stretched to 2.0 times in a 142°C triethylene glycol liquid drawing tank. .2.5.2.
The same procedure as in Examples 1 to 5 was carried out except that the stretching was 75 times and 3.0 times.

The results are shown in Table 1.

Comparative Example 1 Varini, a substitute for the ultra-high molecular weight polyethylene used in Example 1
η): The same procedure as in Example 1 was performed except that 3.5 dl/g high-density polyethylene was used. The results are shown in Table 1.

[Brief explanation of drawings]

FIG. 1 is a side sectional view of the manufacturing apparatus of the present invention. 1...Heating cylinder 2...Grooved cylinder 3...Screw 5...Mandrel 6...Outer die 8...Tube splitting device

Claims (2)

[Claims] (1) Ultra-high molecular weight polyethylene with an intrinsic viscosity [η] of 5 dl/g or more is melted in a screw extruder, and then the mandrel rotates with the rotation of the screw.
A method for producing a drawn ultra-high molecular weight polyethylene yarn, which comprises extruding it through a tube die with /D of 5, cooling it, dividing the obtained tube in the machine direction, and then drawing it. (2) From the extruder side, at least L consists of an extruder consisting of a grooved cylinder and a screw with a compression ratio in the range of 1 to 2.5, a mandrel connected to the tip of the screw and rotating with the rotation of the screw, and an outer die.
/D is 5, resin flow path cross-sectional area S_1 at tube die inlet
and the resin flow path cross-sectional area S_2 at the middle part of the tube die (
S_1/S_2) is in the range of 0.5 to 3.0, and the ratio (S_2/S_
3) An apparatus for producing a raw yarn for drawn ultra-high molecular weight polyethylene yarn, comprising a tube die and a tube dividing device in which the value of 3) is in the range of 1.0 to 3.0.