JPS60231743A - Production of high-molecular polyolefin molding - Google Patents

Abstract

PURPOSE:To obtain the titled molding having excellent resistance to filament separation, knot tenacity and tear strength, by removing a solvent in a gel-form molding obtd. from a soln. of a high-molecular polyolefin, incorporating a styrene monomer in the molding and orienting it by heating. CONSTITUTION:A gel-form molding is molded from a soln. of a high-molecular polyolefin (e.g. a soln. obtd. by dissolving PE or PP having a weight-average MW of 2,000,000 or above in a solvent such as paraffin oil by heating). After the solvent in the gel-form molding is removed, a styrene monomer (e.g. o-, m- or p-methylstyrene) is incorporated in the molding and the mixture is oriented by heating. In this way, resistance to filament separation, knot tenacity and tear strength can be greatly improved without detriment to high elasticity and high strength inherent to the oriented molding. The resulting fiber is suitable for use in the production of ropes and cables which are subjected to hard friction or twist. Further, the fiber has a high buckling strength and hence it is also suitable for use as monofilament and net.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a high molecular weight polyolefin molded article, and in particular, a method for manufacturing a high molecular weight polyolefin molded product, such as a high strength and high modulus fiber or film having excellent splitting resistance, knot strength and tear strength. The present invention relates to a method for producing a molecular weight polyolefin molded article.

A method for producing fibers with high elastic modulus and high strength using ultra-high molecular weight polyethylene as a raw material is known, for example, from Pennings (A
: f', Penninge), Japanese Patent Application Laid-Open No. 1983-10
It is described in JP-A No. 7506, Japanese Patent Application Laid-Open No. 58-5228, etc. These methods involve dissolving ultra-high molecular weight polyethylene in a non-volatile solvent at high temperature, performing solution spinning to obtain a gel-like fiber, and then drawing this, or using non-volatile polyethylene contained in the gel. The fiber is obtained by extracting the solvent with a volatile solvent and hot stretching it to the appropriate elastic modulus and strength.

However, although these methods make it possible to obtain high-modulus and high-strength fibers from ultra-high molecular weight polyethylene, these fibers do not suffer from the properties characteristic of highly oriented and crystallized chain polymers. . In other words, as the degree of orientation increases, the elastic modulus and strength in the direction of the orientation axis asymptotically approach the crystal elastic modulus and strength, but anisotropy occurs in the strength and the elastic modulus and strength in the direction perpendicular to the orientation axis become relatively weak. . Therefore, this fiber has significant vertical cracking or splitting, and when trying to obtain tow prepreg or cloth using a normal loom or knitting machine, it is bent and rubbed when passing through guide pulleys, kite rolls, kite ribs, etc. The disadvantage is that the fibers are divided into many fine fibers, making it difficult to operate the device.

For example, Japanese Patent Application Laid-open No. 5
No. 8-169521 describes a coated fiber that prevents fibrillation of fibers by coating filaments of ultra-high molecular weight polyolefin with a polymer having the crystallinity of ethylene or propylene.

However, since this coated fiber uses a polymer to coat the filament, it is difficult to impregnate the micropores in the filament with the polymer, and prevention of fibrillation of the filament is done from the surface, so improving the splitting resistance is difficult. It wasn't enough.

The present invention aims to improve these drawbacks of molded products having high strength and high elasticity obtained from high molecular weight polyolefins obtained by conventional methods. A high molecular weight polyolefin characterized in that a gel-like molded product is completely molded, the solvent in the gel-like molded product is removed, a styrenic monomer is included in the gel-like molded product, and then the gel-like molded product is heated and stretched. This is a method for manufacturing a molded article.

The high molecular weight polyolefin used in the present invention is a crystalline olefin homopolymer or copolymer, and has a weight average molecular weight of 1.000.000 or more, preferably 1.000.000 or more, particularly preferably 2,000 or more.
0,000 or more, such as polyethylene, poly-10-pyrene, ethylene-propylene copolymer, polybutene-1, polymethylpentene-1, and polyoxymethylene. Among these, polyethylene or boria pyrene having a weight average molecular weight of 2:00 o:no o or more is preferred.

In addition, the styrenic monomonomer used in the present invention may be formed from a gel-like molded product formed from a solution of high molecular weight polyolefin 1, which will be described later. Examples include styrene or its derivatives that undergo radical polymerization. Styrene derivatives include styrene methyl, ethyl, isopropyl, t
- Substituted with alkyl groups such as butyl, vinyl groups, cyclohexyl groups, amino groups, oxy groups, methoxy groups, cyan groups, and other halogens such as fluorine, chlorine, odoriferous, and iodine. Ortho, meta or para substitutions are preferred. Among the above styrenic monomers, ortho-, meta-, or para-methylstyrene is preferable, and a mixture of ortho- or meta-methylstyrene mainly consisting of para-methylstyrene or para-methylstyrene is particularly preferable from the viewpoint of reactivity and vapor pressure. . In addition, these styrene monomers can be used as a mixture of two or more or as a mixture with other polymerizable monomers, such as incyanuric acid, vinylnaphthalene, vinylviridi/vinicica 10-lactam, etc. Can be used.

The dissolved aFi of high molecular weight polyolefin in the present invention is prepared by heating and dissolving the high molecular weight polyolefin described above in a solvent. The solvent at this time is one that can sufficiently dissolve the polymer, such as saturated aliphatic hydrocarbons, cyclic hydrocarbons, aromatic hydrocarbons, and mixtures thereof. Suitable examples include paraffin oil, aliphatic or cyclic hydrocarbons such as decane, undecane, dodeca/tetralin, and mineral oil fractions having boiling points corresponding to these hydrocarbons. The heating dissolution is carried out at a temperature at which the polyolefin completely dissolves in the solvent, which is higher than the temperature at which it gels during dissolution. The temperature varies depending on the solvent used, but is generally in the range of 140 to 250°C. The concentration of the polyolefin present in the solution is 1-15% by weight, preferably 4-8% by weight.

Next, a polyolefin gel-like molded product is molded from this heated and dissolved solution. This gelation method involves applying the polyolefin solution to an appropriately selected die, for example, a die having holes with a circular, elliptical, X-shaped, or Y-shaped cross section for forming fibers, or a die for forming films, bands, etc. One example is a method of extruding using a hole having a rectangular cross section. The extruded gel-like molded product is heated in a water bath, an air bath, or an extraction solvent at a temperature below the gelling temperature, preferably at 15
Cooling to a temperature of ~25°C at a rate of at least 50°C/min. The resulting gel-like molded product contains the solvent used to dissolve the polyolefin, and therefore requires a solvent removal treatment.

Methods for removing solvent gold from a gel-like molded article include evaporating the solvent by heating the gel-like molding, or extracting and removing the solvent with a volatile solvent, but these methods do not significantly damage the structure of the gel-like molded article. Extractive removal with a volatile solvent is preferred in order to remove the solvent without change. It is preferable to remove the solvent in the gel molded product to 1% by weight or less. Examples of the volatile solvent include hydrocarbons such as pentane, hexane, heptane, and toluene, chlorinated hydrocarbons such as methylene chloride and carbon tetrachloride, fluorinated hydrocarbons such as trichloride trifluoride ethane, diethyl ether, dioxane, etc. and other alcohols such as methanol and ethanol.

The gel-like extrusion containing the volatile solvent from which the solvent has been extracted is dried or dried under conditions that remove the volatile solvent and leave a substantially intact solid network polymer. The styrenic monomer is impregnated in the state in which it is contained.

Impregnation of a polymerizable styrenic monomer (hereinafter referred to as monomer) into a gel-like molded product that has been desolvated, and placing the molded product into the monomer in the presence or absence of a reaction initiator. This is accomplished by immersion.

A reaction initiator is preferably added for effective polymerization, such as benzoyl peroxide, lauroyl peroxide, azobisisobutyronitrile, dicumyl peroxide, etc.

Miwabilogo 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, 2,5-dimethyl-2,5-
Examples include di(t-butylperoxy)hexyne-3 and di-t-butylperoxide. The amount of the reaction initiator added is not particularly limited, but usually 10% of the monomer is added.
Q is 0.005 to 5.0 parts by weight. The temperature of the monomer at this time is a temperature that exceeds the freezing point of the monomer and until the gel-like molded product dissolves in the monomer, specifically, within a range of 90°C after exceeding the freezing point, In particular, it is economically preferable to carry out the reaction at a room temperature of 20 to 25°C. If the temperature of the monomer is below the freezing point, the monomer will not be impregnated into the gel-like molded product, whereas at high temperatures exceeding 90°C, the gel-like molded product will dissolve in the monomer or the polymerization rate will increase significantly. , which is also unfavorable because the monomer evaporates. Further, the immersion time of the gel-like molded product in the monomer is selected depending on the amount of monomer added by polymerization in the gel-like molded product in the heating stretching of the gel-like molded product described below. The preferred amount of the polymer added by polymerization in the gel molding is titα5 to 25% by weight, particularly preferably in the range of 1 to 5% by weight. If the amount of heavy θ material added is less than 0.5% by weight, the fiber splitting resistance, knot strength, tear strength, etc. of the molded product will not be improved, and if it exceeds -25% by weight, the high elasticity and high strength of the molded product will be impaired. undesirable as it may cause damage.

Next, the gel-like molded product impregnated with the monomer is heated and stretched in one or more stages. The temperature at this time must be such that the monomer impregnated into the gel-like molded product is polymerized and the gel-like molded product can be sufficiently oriented. Specifically, it is preferable to carry out the process from the softening point of the gel-like molded product to the melting point, particularly just below the melting point. For example, in the case of polyethylene, the temperature is 11
0-140℃, 110-160 for polypropylene
Preferably, the reaction is carried out at ℃. If the temperature during stretching exceeds the melting point, the gel-like molded product cannot be oriented, while if it is below the softening point, the monomers will not be sufficiently polymerized, and a molded product with high strength and high elasticity will be obtained. This is not preferred because it is not possible to obtain the necessary stretching ratio. The tensile strength and elastic modulus of a molded product are proportional to the stretching ratio, so if the strength is to be increased, it is necessary to increase the stretching ratio.
The stretching ratio is at least 10, preferably 20 or more.

The stretched molded product is heat-treated and dried to remove unreacted monomers.

The method of the invention can be carried out in a batchwise and continuous manner. Next, an example of an apparatus for continuous production using the method of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic side view showing an example of an apparatus for producing fibers according to the method of the present invention.

A high molecular weight polyolefin 1 and a non-volatile solvent 2 are supplied to a mixing tank 3 and made into a slurry by a stirrer 4. This slurry is continuously sent through a tube 5 to a heated stirring tank 6 and stirred by a stirring plate 7 to form a uniform solution. This solution is sent to a spinning die 9 by a gear pump 8 and subjected to solution spinning.

The extruded solution 10 is immediately cooled and gelled in a cooling tank 11 to become a yarn 12. The gelled fibers 12 are fed by rolls 13 to an extraction tank 15 using a volatile solvent 14 to extract and remove non-volatile solvents, and then sent to a drying chamber 1 by rolls 16.
7 to obtain dry gel fiber 1B (xerogel). The dry gel fiber 18 is fed by a roll 19, passes through a dipping tank 21 containing 2° of monomer, is impregnated with monomer, and is led to a drawing process. The gel fiber 22 containing the monomer 20 is rolled on rolls 23 and 25.
, 27.29 Cylindrical heating machines with different temperatures 24, 26.2
8, tfC, is wound, and stretched in three stages while changing the temperature. At the same time, the monomer contained in the gel fiber is polymerized, and the weight of the monomer is distributed between the oriented crystals of the stretched fiber 30. Construct a union. The drawn fibers 3o are dried in a heat setting tank 31, passed through a roll 32, and then wound into a winder 33.

As described above, according to the method of the present invention, the fiber splitting resistance, knot strength, and tear strength of the tube can be significantly improved without impairing the high elasticity and high strength of the stretched product obtained from the high molecular weight polyolefin. For example, the fibers obtained by the method of the present invention are suitable for ropes, cables, etc. that are subject to strong friction and twisting, and are also resistant to buckling, making them suitable for applications such as single yarns and nets. In addition, it can be used for secondary processing of tow, prepreg, cloth, etc. using normal techniques, expanding its use as a reinforcing material for composite materials.

Examples of the present invention are shown below. The test method is as follows.

(1) Tensile modulus, using a strong Kani Instron type tensile testing machine, chaff distance 25 mm, tensile speed 5 IWI/min,
The fibers were subjected to a tensile test at a temperature of 25°C.

(2) Knot strength: The fibers were tied once and determined by the above tensile test. (3) Resistance to splitting. Two fibers with one end fixed were arranged parallel to each other at a perpendicular angle and 5 crn apart. 1 on each metal rod
Wrap it around, lower the load to 6 times the fiber denier on the other end,
The metal rod was moved vertically in parallel at a distance of f 5 cyn at a speed of 60 times/minute, and the total number of times the fibers were cut was determined.

(4) Content of polyparamethylstyrene (PPMS):
The entire drawn fiber was extracted with chloroform and the weight of the dissolved portion was calculated. Note that PPMS was confirmed by infrared analysis.

Example 1 Polyethylene 7 having a weight average molecular weight of 2,400,000 was added to liquid paraffin [Crystoll 322 (trade name) manufactured by Esso Oil Co., Ltd.] to prepare a mixed liquid having a weight ratio of 4.0. Per 100 parts by weight of this mixed solution, 2.6-di-t-butyl-P-cresol (1125 parts by weight) and tetrakis[methylene-5
-(4s-sheett,-phthyl-4-hydroxyphenyl)-propionate comethane L (125 parts by weight) was added and mixed at room temperature to prepare an emulsion liquid.

This emulsion liquid was filled into an oil-jacketed autoclave equipped with a stirrer, heated to 200° C., and stirred for 2 hours to obtain a solution. This solution was spun at 1,200°C using a conical die with a spinning diameter of 21IIm at a speed of 6cm'' and 7 minutes.
It was passed through a 15-20° C. water bath installed in an IK and rapidly cooled to obtain gel-like fibers. This gel-like fiber was continuously wound onto a bobbin having a diameter of A5 crn at a speed of 1.2 m/min.

A bobbin of gel-like fibers was immersed in methylene chloride kept at room temperature to extract fluid valine from the gel-like fibers. After two extractions every 8 hours, the methylene chloride was evaporated to obtain dry gel-like fibers.

The dried gel-like fibers were immersed for 2 hours in rose methyl styrene at 23° C. containing 4% by weight of a reaction initiator (benzoyl peroxide).

The gel fiber impregnated with rose methyl styrene containing this reaction initiator was drawn using a 2 m long oil-jacketed cylindrical heating tube at a drawing temperature of 115°C and a drawing speed of 2.0 m/min. , winding speed 4, O? F! /min, second stage stretching temperature 125°C, specific cutting speed 2. Om 1 minute, winding speed 1 [LOm/min and third stage stretching temperature 135°C, specific speed 2. Stretching was carried out in three stages: OmZ min and winding speed Rom/min to obtain a fiber with a stretching ratio of 40.4. Table 1 shows the properties of the fibers obtained by heat-treating the drawn fibers at 60° C. for 24 hours.

Examples 2 to 15 Stretched fibers 1 were obtained in the same manner as in Example 1 except for changing the amount of Bolivara methyl styrene (hereinafter referred to as PPMB) added to the dry gel-like fibers and the stretching ratio.

The properties of this drawn fiber are also listed in Table-1.

Comparative Example 1 The dried gel-like fiber obtained in Example 1 was
Using a cylindrical heating tube with an oil jacket, the first stage was drawn at a stretching temperature of 125°C, a specific speed of 2.0 m/min, and a winding speed of 1.
Same as Example 1 except that 2.5 m/min and the second stage were two-stage stretching at a stretching temperature of 155° C., a specific speed of LOm of 1 min, and a winding speed of 4.0 m/min, and the stretching ratio was 12.5. A drawn fiber was obtained. The properties of this drawn fiber are also listed in Table 1.

Comparative Examples 2 to 6 Stretched fibers were obtained in the same manner as in Comparative Example 1, except that the stretching ratio of the dry gel fiber was changed. The properties of this drawn fiber are also listed in Table-1.

Table 1 Examples 16 to 20 Stretched fibers were obtained in the same manner as in Example 1, except that the dried gel-like fibers obtained in Example 1 were immersed in paramethylstyrene containing 5% by weight of divinylbenzene. The properties of this drawn fiber are shown in Table 2.

Table-2 *A polymer of paramethylstyrene and divinylbenzene.

Example 21 In Example 1, a liquid paraffin solution with a concentration of 8% was prepared using poly-10-pyrene with a weight average molecular weight of 2.5 million instead of polyethylene, and a gel-like fiber completely impregnated with paramethylstyrene was drawn. In the first stage, the stretching temperature was 115°C, the drawing speed was 20 m/min, and the winding speed was 40 m7.
2nd stage drawing temperature 135℃, combing speed 2.0m
/min, winding increase speed 10.0 m/min, third stage stretching temperature 155°C, drawing speed 2.0 m/min, winding speed 3.0
A drawn fiber was obtained in the same manner as in Example 1, except that the drawing was carried out in 3/7 stages and the drawing ratio was set to 155. The properties of this drawn fiber are shown in Table 5.

Comparative Example 7 The dried gel-like fiber obtained in Example 21 was
Using a cylindrical heating tube with an oil jacket, the first stage was at a stretching temperature of 135°C, the drawing speed was 2.0 m/min, the winding speed was 20.0 m/min, and the second stage was at a stretching temperature of 155°C.
Example 21 except that the drawing speed was 2.0 m/min, the winding speed was 4.2 m/min, and the drawing was carried out in two stages of 7 minutes, and the stretching ratio was 15.3.
A drawn fiber was obtained in the same manner as above. The properties of this drawn fiber are also listed in Table 3.

Table-3

[Brief explanation of the drawing]

FIG. 1 is a schematic detailed view showing an embodiment of the manufacturing method of the present invention. Agents 1) Akira Agent Ryo Hagiwara

Claims (1)

[Claims] (1) After molding a gel-like molded product from a solution of high molecular weight polyolefin and removing the solvent in the gel-like molded product,
A method for producing a high molecular weight polyolefin molded product, which comprises incorporating a styrene monomer into the gel-like molded product, followed by heating and stretching.