JPH08260232A - Production of high-strength yarn from ultrahigh-molecular weight polyolefin film - Google Patents

Abstract

PURPOSE: To obtain a high-strength yarn in high productivity by using an ultrahigh-molecular weight polyolefin. CONSTITUTION: An ultrahigh-molecular weight polyolefin >=500000 in viscosity- average molecular weight is subjected to melt forming into a molten film, and both side edges of the molten film or the solid film obtained by cooling the molten film are firmly held to transversely orient the film, and the resultant film is then slitted longitudinally into tapes, which are then oriented in the machine direction, thus obtaining the objective high-strength yarns.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing a high-strength yarn from an ultrahigh molecular weight polyolefin as a raw material,
More specifically, after extrusion molding the film, it is stretched in the horizontal direction, slit into a tape shape, and then the tape is stretched at a high ratio in the vertical direction to produce a high strength stretched tape yarn or split yarn. Regarding the method.

[0002]

2. Description of the Related Art Conventionally, as a method for producing a high-strength yarn from an ultra-high molecular weight polyolefin as a raw material, a method of dissolving it in a solvent to form a film or a yarn and super-drawing (solvent method, Japanese Patent Publication No. 37-9765) Japanese Patent Laid-Open Publication No. 62-62), or as a modification of the solvent method, a method of mixing and extruding with a wax or the like (Japanese Patent Laid-Open No. 62-62-62).
182349), a method of continuously pressing ultra-high molecular weight polyolefin powder and super-stretching (continuous pressing method, JP-A-2-258237, JP-A-4-49015), or extrusion molding of ultra-high molecular weight polyolefin. Method for producing high-strength yarn by using an inflation film (inflation film method, JP-A-62-104911, JP-A-62-122736)
No. gazette) etc. The solvent method is excellent in that a yarn with good performance can be obtained, but it is costly to dissolve and desolvate and is not practical as an industrial material in terms of cost. The continuous pressing method does not use a solvent and does not have the limitation of extrusion molding unlike the following inflation method, so that it is possible to use a higher molecular weight raw material compared to the other, and therefore a high strength product can be obtained, etc. However, there are problems that the continuous press machine is not good in productivity, and that it is difficult to obtain a thin film, and thus it is difficult to make a fine yarn.
The inflation method has good productivity because it can be extruded, but it cannot use high molecular weight polyolefin.
Due to the entanglement of molecules due to melting during extrusion molding, there is a drawback that high-strength drawing and high-strength products cannot be made.

[0003]

DISCLOSURE OF THE INVENTION The present invention provides a method capable of producing with high productivity, low cost, and high strength while eliminating these drawbacks of the conventional method due to the poor processability of the ultrahigh molecular weight polyolefin. To establish. In order to improve productivity, the film forming method by extrusion molding is most suitable, but it can form a high molecular weight polyolefin at a higher speed than the conventional method, and it does not cause extrusion abnormalities such as melt fracture. A method is required, and a stretching method is required to reduce the entanglement of molecules, which is a problem in melt extrusion, and enable high-stretch stretching. That is, it is an object of the present invention to provide a method for producing a high-strength yarn, which uses an ultra-high molecular weight polyolefin and has good productivity.

[0004]

In order to solve the above problems, the present invention basically adopts a film forming method by a melt forming method. This is because it has the highest productivity and the equipment cost and operation cost are low. The extrusion molding method using a screw extruder or a ram extruder is most suitable for the melt molding method. The disadvantage of the extrusion method is that high molecular weight polymers lack the extrusion horsepower and thus break the screw. In addition, the shearing force at the nozzle may be too large to withstand the pressure of the die or barrel. Usually, the solution is to raise the temperature, increase the pressure resistance mechanically,
It can be solved by making the land of the die extremely small to reduce the shearing force. In the present invention, the problem has been solved by further blending a heat-flowable substance having a molecular weight of 500,000 or less or by coextruding multiple layers to reduce the shearing force. The extruder must be of high horsepower to allow extrusion of ultra high molecular weight polymers. Further, it is desirable that the screw is not easily damaged. Further, an extruder capable of extruding even when a thermoplastic low-molecular substance is mixed is more desirable. The extruder type uses ultra high molecular weight polyethylene and paraffin, and also uses powdered resin, powdered additive, powdered heating fluid material, etc., so it is desirable to have a large compression ratio and to be a non-slip type. . In order to solve these problems, it is appropriately selected and used from the means of increasing L / D, using a screw with a large root, and roughening the barrel side.

As a film forming method, there are an inflation film method using a circular die and a T-die film method. For T dies, the use of multilayer dies is particularly suitable for the present invention. When the shear rate at the die land is high, melt fracture occurs in the ultra-high molecular weight polyolefin, but it is necessary to shorten the die land, increase the die gap, raise the die temperature, and the like. In addition, as a modification of the circular die, the above-mentioned JP-A-62-62
Although a method using a rotating mandrel according to Japanese Patent Laid-Open No. 122736 can also be adopted, even in this method, there is a case where the outer die portion has a large resistance and a high molecular weight melt cannot be extruded. The inventors of the present invention have also conducted extensive studies in that regard, and as a result, a resin layer having a multi-layer structure is provided in the outer die portion, and a layer of a low-viscosity substance is provided on the surface in contact with the outer die. Allowed extrusion of the molecular weight melt. In this case, this low-viscosity substance fluid requires a high-pressure pump such as a gear pump or a plunger pump because the extrusion amount of the ultra-high molecular weight polyolefin is high and the extrusion amount is not stable only with an extruder.

For the film formation after leaving the extruder, the usual film formation method can be used as it is. In the film formation of the present invention, it is desirable that the draft ratio is not high, and in the case of the blown film, it is desirable that the blow up ratio (BUR) is also small. that is,
By suppressing the orientation of the film as much as possible, it is possible to suppress uneven thickness of the film, uneven orientation, and variation in crystallinity as much as possible, and it is possible to prevent the following uniformity of horizontal stretching and denier unevenness of the vertical stretched product. One of the features of the film forming method in the present invention is that the water-cooled film forming is applied to the film forming of the ultra-high molecular weight polyolefin. Stretching of ultra-high molecular weight polyolefin has a high stretching tension, which makes it difficult to stretch at a high ratio. By water-cooling the film, it can be stretched with a low stretching tension and can be stretched uniformly.

A problem in producing a high strength yarn from a molten film is that a high molecular weight polyolefin cannot be stretched at a high ratio due to entanglement of molecules caused by melting. As a means for solving this, as a means for solving this problem, the present invention has conducted extensive studies and found that by stretching the film slightly horizontally before the vertical stretching step, it can be stretched to a high ratio in the next vertical stretching, resulting in a high-strength stretched tape. It turns out that I can do it. This means that the laterally stretched molecule contracts in width at the beginning of the next vertical stretching, and the lamella generated by the contraction stretches in the vertical direction, so that the unraveling can be smoothly performed, so that it can be stretched at a high ratio. Is imagined. In this sense, a step of thermally shrinking before the vertical stretching to positively shrink in the width direction may be provided, but the width direction shrinks in the initial heating stage of the vertical stretching step.

As a result of earnest studies on the horizontal stretching means in the present invention, as a result of satisfying the conditions that the stretching tension is large, the horizontal stretching ratio can be quantitatively set, and it is desirable that the stretching is not performed in the vertical direction, It has been found that stretching means for gripping both ears of the film are suitable.
As a horizontal stretching means for gripping and stretching both ears of the film, a tenter system used for biaxial stretching of the film can also be used. In addition, the pulley method horizontal stretching (Briti
sh Patent 849,436, Japanese Patent Publication No. 57-
No. 30368) is particularly suitable for the present invention as a device with a low device cost and a simple device. In the horizontal stretching of the present invention, hot air stretching can be performed, but in the pulley method horizontal stretching, hot water or steam stretching is also possible, and it is easy to obtain a constant temperature. Since a constant temperature with a simple device prevents the occurrence of stretching unevenness,
It is an important factor. For stretching unevenness corresponding to uneven thickness of the film, it is also possible to heat the thick portion of the film in the horizontal stretching process with an infrared heater or hot air, or to use means such as applying cold air to the thin portion. it can.

Horizontal stretching can also be performed when the film is melted. In a normal polymer, the effect of molecular orientation is small even if it is horizontally stretched during melting, and the orientation is not constant. However, with the ultra-high molecular weight polyolefin of the present invention, the flow is small even when melted, and the orientation corresponding to the draw ratio can be stably obtained. The stretching temperature is high at the time of melting, but the stretching tension is small, so that it becomes a simple lateral stretching apparatus. Another characteristic of horizontal stretching when melted is that when melt horizontal stretching is performed using a film extruded by blending a heat-fluid material, transfer of the heat-fluid material to the surface is insufficient only by film formation. The other reason is that the film is transferred to the surface during the horizontal stretching process. It is important that the melt stretch is not too high above the melting point of the ultra high molecular weight polyolefin. If it is too high, the orientation effect is small,
This is because it becomes difficult to quantitatively perform horizontal orientation.

[0010] In the pulley method horizontal stretching, it has been described above that it can be stretched with hot water, but ordinary air-cooled film formation has a high crystallinity and is not suitable for stretching with hot water or the like. On the other hand, for polypropylene, a water-cooled film forming method in which a molten film from an extruder is formed with water or warm water is often used. This is because the water-cooled film formation lowers the crystallinity and can lower the stretching temperature. The high-density polyethylene does not significantly change the crystallinity in the water-cooled film formation and does not contribute much to the lowering of the stretching temperature. However, it has been found that ultra-high molecular weight polyethylene can be stretched in hot water where the stretching temperature is lowered and uniform heating is easy due to water-cooling film formation. From this, it was confirmed that stretching can be performed at a uniform temperature with a simple device. The horizontal stretching ratio does not need to be very high. The high-magnification stretching may be harmful in that it can shrink to form a lamella after the horizontal stretching. Further, if the horizontal stretching ratio is high, the subsequent vertical stretching becomes difficult and the stretching unevenness is large. Normal horizontal stretching in the solid state is at a stretch ratio of 1.5 to 5 times, preferably 2 to 3 times. When the film is in a molten state, it is 1.5 to 8 times, preferably 2 to 5 times, which is slightly higher than this magnification.

In the present invention, after the film formation, the film is stretched horizontally, then slit in the tape direction in the vertical direction, and then stretched vertically.
Vertical stretching requires a longer stretching zone. As the vertical stretching means, roller stretching, hot air stretching, hot plate stretching, hot water stretching, rolling and the like can be used, and it is desirable to use these stretching means together and perform multi-stage stretching. When rolling is used, it is possible to carry out rolling to a certain ratio, then vertical slitting, and further normal vertical stretching, which is included in the present invention. The vertical stretching ratio must be as high as possible, and is usually 10 times or more, preferably 30 times or more, and more preferably 50 times or more.

The ultrahigh molecular weight polyolefin used in the present invention is a polymer or copolymer of olefins such as ethylene, propylene, butene, pentene and hexene.
Polymers of olefins are desirable because they can achieve high crystallinity, and high density polyethylene and polypropylene are particularly desirable. These include those obtained by copolymerizing other polymers. These ultrahigh molecular weight polyolefins preferably have a viscosity average molecular weight of 500,000 or more, more preferably 1,000,000 or more. For ultra high molecular weight polyethylene, 135
The intrinsic viscosity measured with a decalin solution at 5 ° C is 5 dl / g or more, preferably 10 dl / g or more. In the present invention, an ultra-high molecular weight polyolefin having a higher molecular weight than that of the conventional method can be used by using a heating fluid material together or by using a special die as described later. The higher molecular weight has a higher potential to make the stretched yarn higher in strength and elasticity. A polymer having a low molecular weight cannot be stretched at a high ratio, and it is difficult to achieve high strength.

The substance to be blended with or co-extruded with the ultra-high molecular weight polyolefin is a heat-flowable substance, and it is necessary that the viscosity is lower than that of the ultra-high molecular weight polyolefin during extrusion molding of the ultra-high molecular weight polyolefin. The reason is that the difficulty in extruding the ultrahigh molecular weight polyolefin is alleviated. The molecular weight is 500,000 or less,
It is preferably 100,000 or less. Oils that are in a liquid state at room temperature become solid if cooled, so
For convenience, it is included in this heated fluid material. Examples of the heat fluid material used in the present invention include polyethylene such as high-density polyethylene, polypropylene, various modified polyolefins, various waxes, ethylene vinyl acetate copolymer,
Solvents for polyamides, polyesters, unsaturated polyesters, fluoropolymers, silicone polymers, polyethylene glycols, ultra high molecular weight polyolefins such as glycerin or decalin, and the like. Since polyethylene glycol and glycerin are water-soluble, they can be
It has the feature that it can be easily removed with water. These heat-fluidizable substances not only alleviate the difficulty of extrusion but also contribute to improve the surface properties of the yarn, and the properties of the yarn such as thermal adhesiveness, dyeability and miscibility with the FRP matrix. Can be given. In addition, low molecular weight substances such as wax are removed during film formation and stretching, and are actively removed in products.

Various additives and pigments such as adhesives, antioxidants, anti-UV agents, anti-slip agents, lubricants and antistatic agents are added to these ultra-high molecular weight polyolefins and heat-fluidizable substances.
Colorants such as dyes, flame retardants and the like can be added in the same manner as in the case of normal film extrusion. Since the extrusion molding in the present invention is carried out at a particularly high temperature, there is a concern that the ultra-high molecular weight polyolefin is oxidized. However, by adding a large amount of an antioxidant or a heat deterioration inhibitor to this heat-fluidizable substance, the ultra-high molecular weight Another feature of the present invention is that extrusion molding can be performed without deteriorating the properties of the polyolefin.

The high-strength yarn according to the present invention can easily be produced as an ultrahigh molecular weight polyolefin component in an amount of 10 g / d or more, preferably 15 g / d or more, and further 20 g / d or more. Since the strength becomes relatively smaller as the amount of the heated fluid substance increases, it is necessary to calculate by subtracting the weight of the heated fluid substance.

The high-strength yarn of the present invention includes a vertical stretched tape and a split yarn obtained by splitting it.
By drawing at such a high draw ratio, a yarn having a high strength and a high elastic modulus is obtained, and its specific strength depends on the type of ultra-high molecular weight polyolefin and the properties and proportion of the heat-fluidizable substance to be mixed. In the case of split yarn, the strength is weak when measured without twisting, but the strength can be 80 to 90% of the yarn strength by applying the optimum twist.

[0017]

Embodiments of the present invention will be described in detail below with reference to the drawings.
1A and 1B show T-die film formation and horizontal stretching in a molten state in the present invention, FIG. 1A is a plan view, and FIG. 1B is a side view.
The extruder 1 showed the example which used the screw 2 with a large root diameter. Since the screw 2 has a large root, a high horsepower motor can be used, and even if the horsepower is large, the screw 2
Will not be damaged. In order to ensure the feeding, it is effective to make the barrel 3 side rough. This extruder 1
Is characterized in that it can be surely extruded even when a low-viscosity wax or the like is mixed. The ultra-high molecular weight polyolefin melt-kneaded by the extruder 1 or the mixed heat-fluidizable substance is guided to the T-die 4 and extruded as a sheet or film 5. Since this film is stretched horizontally, it is necessary to extrude the film 5 thicker by that amount. The extruded film 5 is stretched horizontally in a hot air chamber 6 by a pulley type horizontal stretching device without being solidified. The horizontal stretching device includes a pair of stretching pulleys 7a,
7b and belts 8a, 8b (8b) which are fitted and circulate
Is not visible in the shadow of 8a, so it is omitted in FIG. 1A. In FIG. 1B, the belt is omitted because it is complicated.) The two ears of the film are gripped, and the tracks extending in the end spread of both pulleys 7a and 7b are stretched horizontally. To be done. The film is not solidified by the hot air in the hot air chamber 6 during the stretching process. The horizontally stretched film 9 that has been stretched is cooled by the cooling roll 10,
A large number of tapes 12a, 12b, 12c by a leather (razor blade) slitter 11 placed on a certain pitch
... is slit, taken up by the nip rolls 13a and 13b, and guided to the next vertical stretching step.

The horizontal stretching system for film formation shown in FIG. 1 is suitable for mixing and extruding a heated fluid material.
Most of the heat-fluidizable substances are gradually extruded onto the surface of the film during film formation or during the process of melt-stretching. It is desirable that the draft ratio to the horizontal stretching device after film formation in FIG. 1 should not be large. If the draft ratio is large, the effect of the horizontal alignment is not obtained unless the horizontal stretching ratio is increased. At this time, unevenness in horizontal stretching becomes large. Usually, the vertical draft ratio is preferably in the range of 1 to 3. By using a multi-layer die as the T-die in FIG. 1, it is possible to obtain a multi-layer extruded film having a heat-fluidizable substance as a surface layer.

FIG. 2 shows an example of film formation by the inflation method. The extruder 22 composed of the screw 21 extrudes the ultra-high molecular weight polyolefin, and the screw tip 2
The groove 3 of the screw is not cut, and 3 serves as a rotating mandrel. The heated fluid material is fed by the gears 24a and 24b of the gear pump, distributed by the manifold 25 around the barrel, and is rotated by the rotating mandrel 23.
Part covers the circumference of the melt of the ultrahigh molecular weight polyolefin, forms the surface of the blown film 26 and is extruded. The blown film 26 is water-cooled with water 27 in a range where the frost line does not come out, passes through a guide plate 28, nip rolls 29a and 29b, is cut open with a knife 30, and is guided to a horizontal stretching step.
The internal pressure of bubbles in the inflation film 26 is controlled by introducing internal pressure adjusting air through the pipe 31.
As a water-cooled film forming method, since the ultrahigh molecular weight polymer has a high internal pressure, the present application is filed under Japanese Patent Publication No. 47-47.
No. 084, Japanese Patent Publication No. 47-47086, and Japanese Patent Publication No. 48-22966 are effective, and of these, those using a mesh are particularly suitable. Nip roll 29a
The groove 33 is dug as shown in FIG.
Although an example of a gear pump is shown in FIG. 2 for supplying the heated fluid substance, other methods can be used as long as the device has a high-pressure pump mechanism such as a high-pressure extruder.

FIG. 4 shows an example of a three-layer T-die film formation of an ultrahigh molecular weight polyolefin a and a heat fluid material p.
4A shows a front view and FIG. 4B shows a side view. As the three-layer T-die, a three-layer internal stacking type manifold flat die (multi-manifold die) can be used, but the structure is complicated and the die is expensive, and the internal pressure is high. Melt fracture is likely to occur. FIG. 4 shows a system in which the ultra-high molecular weight polyolefin a and the heat-fluidizable substance p are combined in the adapter 43. Ultrahigh molecular weight polyolefin molten resin a is kneaded by an extruder and introduced to an adapter 43 through a conduit 41. The heat-flowable substance p is kneaded from another extruder, and the conduit 4
2 is led to the adapter 43, and the adapter 43
It is divided into branch pipes 44 and 45 inside, and is joined on the front and back sides of the ultrahigh molecular weight polyolefin a at a confluence point 46 in the adapter 43. The combined resin flow 47 is a T-die 48.
Is spread along the coat hanger type groove 49 and is guided to the die lip 50. From the die lip 50, a molten film of ultra-high molecular weight polyolefin having a layer of the heat-fluidizable substance p on both sides is extruded. The heated fluid material p kneaded by the extruder is preferably supplied to the adapter 43 by a high pressure pump such as a gear pump. This is because the ultrahigh molecular weight polyolefin resin a in the adapter has a high melting pressure. The method of merging in the adapter as described above is also called a feed block die or a combine adapter method, and can be used in multiple layers such as 3 types 3 layers and 5 types 5 layers. In the case of 5 layers of 5 types, the core may be an ultra-high molecular weight polyolefin, the surface thereof may be an adhesive material compatible with the ultra-high molecular weight polyolefin, and the outermost surface may be an adhesive material compatible with the matrix. By adopting the method of merging in the adapter as in the present invention, it becomes possible to use an ultrahigh molecular weight polyolefin having a higher molecular weight, which has been impossible in the past, and a stretched tape having higher performance can be obtained. It can also be used in a circular die as shown in FIG.

FIG. 5 shows an example of water-cooled film formation in the T-die film formation. The film 52 extruded from the T-die 51 is the tank 5
It is water-cooled with the water 54 stored in 3. Also in this case, it is desirable that water cooling be performed within a range where the frost line does not appear.
The water-cooled film 55 has nip rolls 56a, 56
It is led to a horizontal stretching process via b. FIG. 6 also shows another example of the cooling method in the T-die film formation. The film 62 coming out of the T-die 61 is cooled by the chill roll 63 and guided to the horizontal stretching step.

FIG. 7 shows another example of a horizontal stretching apparatus, which is an apparatus capable of hot water stretching. The water-cooled film 71 is introduced into a tank 72 in which hot water is stored, and is stretched horizontally by a pulley type horizontal stretching device. The horizontal stretching device includes a pair of stretching pulleys 73a and 73b that rotate in hot water and belts 74a and 74b that are fitted to the stretching pulleys 73a and 73b and circulate.
The two ears of No. 1 are gripped, and the pulleys 73a and 73b are stretched horizontally by the orbits that spread toward the ends. Since it is water-cooled, it can be stretched at a uniform temperature of hot water, resulting in such a simple horizontal stretching device. The example of FIG. 7 shows an example of hot water drawing, but the tank is reversed and the direction of rotation of the drawing pulley is reversed.
The tank can also be steam-stretched by storing steam.
As described above, hot-water stretching or steam stretching is suitable for the water-cooled film, but hot-air stretching is used for the air-cooled film because the suitable stretching temperature exceeds 100 ° C.

Examples 1 to 4 and Comparative Examples 1 to 2 Table 1 shows the yarns produced by a conventional method as examples and comparative examples of the method for producing the high-strength yarn of the ultrahigh molecular weight polyolefin film-formed and stretched according to the present invention. Shows physical properties.

[0024]

[Table 1]

In Table 1, what is indicated as ultra-high polyolefin is the ultra-high molecular weight polyolefin used in the present invention, and a, b and c are shown below. a ... Ultra high molecular weight polyethylene, viscosity average molecular weight 1.1 million b ... Ultra high molecular weight polypropylene, viscosity average molecular weight 850,000 c ... Ultra high molecular weight polyethylene, viscosity average molecular weight 280,000 Shown are the heat-flowable substances used in the present invention, and p, q, and x are shown below. The ratio of the fluidizing material to the ultra high molecular weight polyolefin is shown in percent. p ... Paraffin wax, Sanyo Kasei Co., Ltd. Sunwax 161-P antioxidant Irganox 1010 300 ppm q ... High-density polyethylene, Mitsubishi Kasei ER010S x ... Modified polypropylene, Mitsubishi Kasei Corp. Novatec The outline of the 390P film forming apparatus is shown in the above figure. The resin temperature indicates the resin temperature in the die. The expansion ratio indicates the blow-up ratio (BUR) in inflation film formation. The film thickness indicates the film thickness immediately before horizontal stretching. The outline of the horizontal stretching method is shown in the above figure. Vertical stretching was carried out by multi-stage stretching in a free space. Strong elongation is JI
It was measured by SL 1069, and the measurement was performed at a chuck interval of 100 mm and a pulling speed of 100 mm / min.

Example 1 is a case where ultra-high molecular weight polyethylene was formed and stretched by the film forming apparatus shown in FIG. The screw 2 of the extruder 1 has an outer diameter of 40 mm at the base and an outer diameter of 30 m at the tip.
m and L / D are 24 millimeters. 250 mm wide T
A film 5 having a thickness of 320 μm was formed from the die 4. While the film is in a molten state, a pair of drawing pulleys 7a and 7b that draw a trailing orbit in the heating chamber 6 and drawing belts 8a and 8b that circulate in the drawing pulleys hold the film and draw it horizontally. Double stretch,
The horizontal stretched film 9 is used. The horizontal stretched film 9 is cooled by a cooling roll 10 and then 20 m by a leather slitter 11.
Many slit films 12a, 12b, 12c of m width
After that, the nip rolls 13a and 13b transfer the film to a drawing process. In Example 1, since the heating fluid material was not used, melt fracture occurred in the film unless the screw rotation speed was 10 or less. Although the drawing process is not shown, it is drawn in three stages at 150 ° C. in a free space, the draw ratio is 35, and the tensile strength is 24.7 g /
d, a flat yarn having a tensile elongation of 2% could be obtained.

In Example 2, 15% by weight of paraffin wax powder having a melting point of 55 ° C. was mixed with the same ultrahigh molecular weight polyethylene powder as in Example 1 as a resin, and the mixture was supplied from a hopper. The film forming method, the horizontal stretching method, and the vertical stretching method are the same as those in Example 1, but the film forming temperature, the stretching temperature, the strong elongation, etc. are shown in Table 1. During the film forming process, the horizontal stretching process, and the vertical stretching process, the wax is gradually bleeded and removed from the ultrahigh molecular weight polyethylene system.

Example 3 is an example in which a tubular film is formed with high density polyethylene as an outer layer by the film forming method of FIG.
The blow-up ratio (BUR) is 1.1, and the draft ratio in the vertical direction is 3. Fig. 2 Japanese Patent Publication No. 47-4708
In the water-cooled film formation of Japanese Patent No. 4, the water temperature of the cooling water 27 was 55 ° C. In the horizontal stretching method, stretching is performed 2.5 times at 125 ° C. in the heating chamber 6 shown in FIG. Thereafter, the tape is slit in the vertical direction and then vertically stretched in the same manner as in Example 1.

In Example 4, the apparatus of FIGS. 4 and 5 was used to form a film of ultra-high molecular weight polypropylene and modified polypropylene on both surface layers by using a three-layer T die. In this case, the water temperature of the water 54 was 54 ° C. Was room temperature (22 ° C.). This was horizontally stretched in hot water of 98 ° C. by the horizontal stretching device of FIG. 7. Vertical stretching and the like were performed in the same manner as in Example 1.

Comparative Example 1 is the same as Example 1, but in the case of ultra-high molecular weight polyethylene c having a low molecular weight, the draw ratio and the tensile strength after drawing are low. Comparative Example 2 is a case where the same ultra-high molecular weight polyethylene as in Example 1 was used and a film was formed. However, since the lateral stretching was not performed, the vertical stretching ratio and the tensile strength after stretching are low.

[0031]

The ultra-high molecular weight polyolefin film of the present invention can be stretched vertically by slitting it in the vertical direction and then vertically stretching to realize high-strength vertical stretching. Split yarn can be realized. Furthermore, by blending or co-extruding a heat-fluidizable substance, the melt fracture in the die can be reduced, and ultra-high molecular weight polyolefin with a higher molecular weight than before can be formed into a film, and higher strength and higher elastic modulus are possible. You can The addition of the heat-fluidizable substance also serves to improve the surface properties of the product yarn. Specifically, the adhesiveness,
Colorability, dyeability, weather resistance, slip resistance, etc. can be improved. By adding a large amount of an antioxidant or a heat deterioration inhibitor to this heat-fluidizable substance, there is also an effect of enabling extrusion molding without deteriorating the properties of the ultrahigh molecular weight polyolefin. The stretched tape of the present invention is a woven fabric, biaxially, triaxially
Axial weft laminated non-woven fabric, unidirectional

It is processed into a prepreg or the like and used as various reinforcing materials such as bulletproof structures, construction / civil engineering sheets such as explosion-proof sheets, FRTP, FRP, radar domes and concrete reinforcement. Further, the stretched tape of the present invention is processed into split fibers and used for various ropes, the above woven fabrics, and the like.

[Brief description of drawings]

FIG. 1 is an example of an apparatus in which a tape-shaped slit is formed in the vertical direction after horizontal stretching under melting in T-die film formation, A is a plan view
B shows a side view.

FIG. 2 shows an example of an apparatus in which a tubular fluid-cooled film is coextruded with a heating fluid material.

FIG. 3 shows a method for introducing an inflation internal pressure adjusting air introduction pipe in the film forming apparatus of FIG.

FIG. 4 shows an example of an apparatus in which a heated fluid material is merged in an adapter of an extruder and coextruded by T-die film formation.

FIG. 5 shows an example of water-cooled film formation in T-die film formation.

FIG. 6 shows an example of chill roll film formation in T die film formation.

FIG. 7 shows an example of a horizontal stretching apparatus capable of hot water stretching.

[Explanation of symbols]

1: Extruder, 2: Screw, 3: Barrel, 4: T-die, 5: Film in molten state, 6: Hot air chamber, 7: Drawing pulley, 8: Circulation belt, 9: Film pre-oriented in the horizontal direction, 10: cooling roll, 11: leather slitter,
12: tape-like film, 13: nip roll, 21:
Screw, 22: extruder, 23: rotary mandrel, 2
4: Gear pump, 25: Manifold, 26: Inflation molten film, 27: Water, 28: Guide plate, 2
9: Nip roll, 30: Knife, 31: Bubble internal pressure adjusting tube, a, b, c: Ultra high molecular weight polyolefin, p,
q, x: heated fluid material, 41, 42: molten resin conduit,
43: adapter, 44, 45: molten resin branch pipe, 4
6: Confluence point, 47: Flow of molten resin, 48: T die,
49: groove, 50: die lip, 51: T die, 52:
Molten film, 53: water tank, 54: water, 55: film, 56: nip roll, 61: T die, 62: film, 63: chill roll.

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical display location D01D 5/08 110 D01D 5/08 110 5/28 5/28 5/32 5/32 5/42 5/42

Claims (5)

[Claims] 1. An ultrahigh molecular weight polyolefin having a viscosity average molecular weight of 500,000 or more is formed into a melt film by melt molding, and the melt film or a solid film obtained by cooling the melt film is gripped at both ends of the melt film and stretched horizontally. After that, a high strength yarn is produced by slitting a tape shape in the vertical direction and stretching the tape in the vertical direction. 2. An extruded film having two or three layers is formed by co-extruding a heat-fluidizable substance having a molecular weight of 500,000 or less into a surface layer of the film from a die when the ultra-high molecular weight polyolefin is formed into a film. 1. The method for producing a high-strength yarn according to 1. 3. The method for producing a high-strength yarn according to claim 1, wherein when the ultra-high molecular weight polyolefin is formed into a film, a film is prepared by mixing a heat-flowable substance having a molecular weight of 500,000 or less and extruding it from a die. 4. An ultrahigh molecular weight polyolefin melt-plasticized by an extruder and a heating fluid material introduced by a high pressure pump separately from the extruder are merged in an adapter, and then introduced into a film forming die, and the heating fluid material is formed into a film. Both surfaces and core are made of ultra high molecular weight polyolefin. 5. A mechanism in which the tip of the screw of the extruder is composed of a rotating mandrel, the outer die of which has a flow portion of the molten resin of multiple layers, and a fluid which is in contact with the outer die of the multiple layers is pushed by a high-pressure pump. Inflation film extrusion die having.