JPH0333211A - Boiling water-resistant polyvinyl alcohol-based fiber and production thereof - Google Patents

Abstract

PURPOSE:To obtain the subject fiber useful for a reinforcing material of a large-sized tire for high speed, a net, a rope, etc., by blending two kinds of PVA-based polymers respectively having a specified polymerization degree in a specified condition, dissolving the resultant mixture in a solvent, spinning using the dry wet spinning method or the wet spinning method, removing the solvent and subsequently carrying out high-drawing at a high temperature. CONSTITUTION:A PVA-based polymer having >=3000 average polymerization degree is blended with another PVA-based polymer having >=15000 average polymerization degree and >=5000 difference between the polymerization degree thereof and that of the former polymer so that the content of the latter polymer may be >=10wt.%, preferably 20-80wt.%. The resultant mixture is dissolved in a solvent, spun by the dry wet spinning method or the wet spinning method and drawn at >235 deg.C after removal of almost all the above mentioned solvent so that the total draw ratio may be >=18, thus obtaining the objective fiber having >=140 deg.C dissolution temperature in boiling water under 20mg/d load and >=20g/d single filament tensile strength.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention is directed to hot water-resistant polyvinyl alcohol (hereinafter referred to as PVA).
(abbreviated as ) type fiber buttons and their manufacturing method.
The aim is to obtain PVA-based fibers that are suitable for applications that require hot water resistance at high temperatures and abrasion resistance in a water atmosphere, especially in the fields of industrial materials and reinforcement of composite materials. .

(Conventional technology) Conventional PVA fibers are polyamide and polyester.

It has a higher strength and modulus of elasticity than polyacrylonitrile fibers, and in addition to its main use as fiber for industrial materials, it has also been used as a substitute for asbestos fiber in RIIA for reinforcing cement.

In recent technology, the concept of gel spinning and super-stretching of high molecular weight polyethylene has been applied as a method for obtaining PVA fibers with high strength, high modulus, and excellent hot water resistance. @
Kaisho 59-130314.

JP-A-61-1υ8711 has been proposed. However, although these methods yield PVA-based fibers with high strength and high modulus, they cannot provide the high degree of hot water resistance required in some application fields.

That is, since PVA-based polymers are inherently hydrophilic, even if they are made into fibers, there is a problem in water resistance, and conventionally, water insolubilization treatments such as acetalization treatments have been performed. In recent high-strength PVA fibers, the molecular orientation of the amorphous portion that is susceptible to the effects of water has advanced, and dimensional stability against water can now be achieved without the above-mentioned water insolubilization treatment. However, for example, reinforcing materials for cement moldings cured in autoclaves, lobes that are susceptible to friction in wet conditions, high-pressure rubber bows, oil brake hoses, and large passenger car tires, etc. I was still dissatisfied with it.

Also, Japanese Patent Application Laid-open No. 61-289112 (1989-289112)
The weight average degree of polymerization is 200 as in Publication No. 63307, etc.
00 or higher PVA-based fibers are also known, but their production costs are high and their crystallization does not progress sufficiently, making it impossible to obtain fibers with satisfactory hot water resistance.

(Problems to be Solved by the Invention) Therefore, the present invention provides hot water resistant PVA with improved hot water dissolution temperature.
The purpose of this invention is to provide a technique for obtaining fibers without increasing production costs.

(Means for Solving the Problems) That is, the present invention provides 5 111) A PVA polymer having an average polymerization degree of 3000 or more and a PVA polymer having an average polymerization degree of 15000 or more on at least 10 weight plates, and an average polymerization degree of both polymers. The embroidery has a difference of 5000 or more.

A hot water resistant PVA fiber having a hot water dissolution temperature of 140° C. or higher and a single fiber tensile strength of 209/d or higher under 20 η/d.

(2) Average degree of polymerization is 3000 with a difference in degree of polymerization of 5000 or more
The above PVA-based polymer and a PVA-based polymer with an average polymerization ratio of 15,000 or more are mixed so as to contain at least 1 offit% of the latter polymer, and dissolved in a solvent,
Spun by dry or wet method using conventional methods.

A method for producing hot water-resistant PVA-based fibers, which comprises removing most of the solvent and then stretching the fibers at a temperature exceeding 235° C. to a total stretching ratio of 18 times or more. ”.

The requirements of the present invention are as follows.

1) PVA with an average polymerization degree of 3000 or more and an average polymerization degree of 15
A mixed PVA containing at least 10% by weight of PVA of 0.000 or more and having an average degree of polymerization difference between the two polymers of 5000 or more is dissolved in a solvent.

2) When coagulating by dry-wet spinning or wet spinning, uniform gelation is caused by rapid cooling.

3) Perform wet stretching, extraction, drying, etc. using conventional methods.

After removing most of the solvent, the film is dry-stretched at high temperature and at a high magnification.

The feature of the present invention is that by containing PVA with a high degree of polymerization, there are many tie molecules penetrating the crystals and the amorphous core is strengthened, thereby increasing the resistance to hot water. In particular, by mixing PVA with different polymerization degrees, the synergistic effect of the high crystallinity of low polymerization degree PvA and the increase in the number of tie molecules of high polymerization degree PVA allows the hot water dissolution temperature to be 140℃ or higher, which is unprecedented for hot water PV.
A-based fibers are obtained, which can be autoclaved as a cement reinforcing material, and can be applied to reinforcing materials for large high-speed tires that require hot water resistance, reinforcing materials for rubber hoses that use steam, nets and robes that are exposed to hot water, etc. becomes possible.

The contents of the present invention will be explained in more detail below.

The PVA-based polymer referred to in the present invention is a polymer with an average degree of polymerization of 3000 or more determined by a viscosity method in an aqueous solution at 30°C, a linear polymer with a saponification degree of 99.5 mol φ or more, and a low degree of branching. It is. In the case of the present invention, a mixture of two types of PVA-based polymers is used, and the average degree of polymerization is 3,000 or more, preferably 5,000 or more, and 20,000 or less (Al has an average polymerization degree of 15,000 or more, preferably 20,000 or more).
The polymer (B) of 000 or more should be contained in an amount of at least 10% by weight and <Fi20 to 80% by weight. Further, the average degree of polymerization difference between both polymers is 5,000 or more, preferably 8,000 or more. If the content of the highly polymerized polymer (B) is less than 10% by weight, it is difficult to obtain high strength and high hot water resistance. If the average degree of polymerization difference between the two polymers is less than 5,000, the balance between the high stretching and high crystallinity of the low polymerization degree polymer (A) and the increase in the number of intercrystalline tie molecules of the high polymerization degree polymer (B) referred to in the present invention is not achieved. It is difficult to obtain a fiber that satisfies two requirements: high strength, high water resistance, and high strength.

Further, there is no problem in adding boric acid, antioxidants, pigments, oils, etc., but it is preferable to limit the amount added to an extent that does not cause performance deterioration.

Any solvent for PVA polymers may be used, including glycerin, ethylene glycol, diethylene glycol, triethylene glycol, iJ methylene glycol, propylene glycol, butanediol, and 3-methylpentane.
Polyhydric alcohols such as 1,3,5-)su'ol, dimethylformamide.

Examples include dimethyl sulfoxide, diethylene triamine water, and mixed solvents of these for 2 seconds or more, but polyhydric alcohols that gel the produced fibers by rapid cooling are particularly preferred.

The spinning method may be a dry-wet method or a wet-spinning method, but a wet-dry method is preferable in order to obtain uniform gel fibers by rapid cooling.

The coagulation bath may be any alcohol, acetone, alkaline aqueous solution, etc., but an alcohol/solvent mixed system that produces uniform gel fibers is preferred. In order to cause homogeneous gelation, it is preferable to contain 100 parts by weight of the solvent in the coagulation bath and coagulate slowly.

Furthermore, it is preferable to set the solidification temperature to 20'C or lower to obtain a rapid cooling effect.

Wet stretching may or may not be done, but the good housing strength is 3 times or more. This reduces adhesion between fibers.

This is to break the microcrystals and make them amorphous.

Next, solvent extraction is performed, and the extractant may be either alcohol or water.

Drying is then carried out at 130° C. or lower to suppress crystallization and prevent sticking, and almost all of the solvent is removed in the extraction drying step.

Finally, dry heat stretching is performed at a high temperature of 235° C. or higher.

Any stretching method may be used (IJi, two or more stages, dry heat, oil bath, nitrogen gas zone stretching, etc.).

If the stretching temperature is lower than 235°C, oriented crystallization will be insufficient and the molecular chains will be easily disturbed by hot water, resulting in a decrease in hot water resistance. Stretching is performed at a total stretching ratio of 18 times or more. If it is less than 18 times, the orientation of the molecular chains will be insufficient, resulting in decreased hot water resistance and strength.

The non-invention will be specifically explained below with reference to Examples.

The present invention is not limited only to the examples.

Various physical property values and parameters in the Examples described below were measured by the following methods.

1) Viscosity average degree of polymerization pA of PVA Calculated from the measured value of the intrinsic viscosity [η] of an aqueous solution at 30° C. according to the following formula according to JIS K6726.

lag PA = 1.631sg ((η)X 10
'/8.29) 2) Tensile strength and elongation of single fiber, elastic modulus of pre-wetted fiber with v4 sample length 10, 0.25 f/d
The breaking strength and elongation and initial elastic modulus were determined at the initial load and the tensile speed of "sow", and the average value of 5 or more points was adopted.

3) Hot water melting temperature A load of 2 cm per denier was applied to 25 single fibers, and they were suspended in the middle of a sealed cylindrical glass container filled with water. By heating water at a constant rate, the fiber yield rate is 1.
() Maximum value WT at the temperature when the casing or fuse is reached
b was adopted.

Example: A mixture of 1 part by weight of PVA7 with an average degree of polymerization of 17,000 per part of 280,000 PVA2 was dissolved in glycerin at 180°C to give a 4.5-polymer mixture.Then, the solution was heated to 190°C and discharged through a nozzle with a hole diameter of 0.151111 and a number of holes of 8° and dropped into a coagulation bath 25 m below to perform wet-dry spinning.The coagulation bath composition was methanol/glycerin-80/
20, and the temperature was 0°C.

Next, the solvent was extracted in a methanol bath kept at 40° C., and the film was taken up and wet stretched 4 times at a roller speed of 3.5 m/min. After subsequent methanol extraction, 95°C
dried with hot air. Finally, stretching was carried out at a temperature of 252° C. so that the m-stretching ratio was 20.0 times. The resulting drawn yarn had a hot water dissolution temperature of 162°C under a load of 20111F/d.
, single fiber tensile strength is 24.1 f/d and high hot water resistance,
The result is a high-strength fiber.

As Comparative Example 1, the final dry heat stretching temperature in Example 1 was set to 220
The case where the temperature was ℃ was carried out. The total stretching ratio was only 16.8 times, and whitening of the fibers occurred. Load 2 of the obtained drawn yarn
The hot water dissolution temperature at 0 cape/d was 141°C, which was low in hot water resistance, and the single fiber tensile strength was 19.0 f/d, which was also low.Example 2 Average degree of polymerization: 4000 P'/A and average degree of polymerization of 28,000
A mixture of PVA of 60% by weight and 40% by weight, respectively, was added to water to give a concentration of 8% by weight, and at the same time, 0.5% by weight of boric acid/PVA was added to make 100% PVA.
Dissolved at ℃. The solution was then brought to 70°C and the composition was NaOHl Of /j water, NJL2SO4200f
/I water and discharged into a coagulation bath kept at 10° C. for wet spinning. Next, the film was stretched 3 times in the air, the alkali was neutralized, and then stretched 1.8 times with NazSaa 300 f7 hot water at 190°C, followed by solvent extraction in a water bath maintained at 30°C. After drying at 110°C, it was stretched 4 times in a hot air oven at 248°C. The hot water dissolution temperature of the obtained drawn yarn under a load of 20 η/d was 154°C.

The single fiber tensile strength was 21.5 f/d, making it highly heat resistant, strong and delicate.

Example 3 A mixture of equal weights of PVA with an average degree of polymerization of 7,700 and PVA with an average degree of polymerization of 18,000 was dissolved in dimethyl sulfoxide at 90° C. to a pressure of 10% by weight.

Next, the solution was heated to 50° C. and wet-dry spinning was performed. Coagulation bath composition is ethanol/dimethyl sulfoxide = 70
/30, and the temperature was 10°C.

The solvent was then extracted in ethanol kept at 50°C.

It was stretched 7 times with dry heat at 170°C, and then stretched 3 times with a dry heat heater at 245°C. Load of the obtained drawn yarn 1120 strokes/
The hot water dissolution temperature under d is 150°C.

monofilament bow Tensile strength 22.0f/d It was very expensive.

% permit applicant Co., Ltd. nine La Re teenager Reason Man

Claims (2)

[Claims] (1) A fiber containing at least 10% by weight of a polyvinyl alcohol polymer with an average degree of polymerization of 15,000 or more in a polyvinyl alcohol polymer with an average degree of polymerization of 3,000 or more, and the difference in the average degree of polymerization between the two polymers is 5,000 or more, and the load The hot water dissolution temperature under 20 mg/d is 14
Heat-resistant water-resistant polyvinyl alcohol fiber with a single fiber tensile strength of 20 g/d or more at 0°C or higher (2) Average degree of polymerization is 3000 with a difference in degree of polymerization of 5000 or more
The above polyvinyl alcohol polymer and average degree of polymerization 1
A polyvinyl alcohol-based polymer of 800 or more is mixed with a polyvinyl alcohol-based polymer containing at least 10% by weight of the latter polymer, dissolved in a solvent, spun using a dry-wet method or a wet method using a conventional method, and after removing most of the solvent, the mixture is heated at 235°C. 1. A method for producing hot water-resistant polyvinyl alcohol fibers, which comprises stretching the fibers at a total stretching ratio of 18 times or more at a temperature exceeding .