JPH11286826A - Production of polyvinyl alcohol synthetic fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject fiber having high tenacity, elasticity and wet-heat resistance and useful for industrial material, etc., without using complicate process by crosslinking a polyvalent epoxy compound under specific condition in a state e.g. included in a polyvinyl alcohol polymer, etc. SOLUTION: The objective polyvinyl alcohol synthetic fiber is produced by including or applying preferably 0.1-10 mol.% (based on the repeating constituent unit of the polymer) of a polyvalent epoxy compound such as ethylene glycol diglycidyl ether into a polyvinyl alcohol polymer (having a degree of saponification of preferably 90-99.99 mol.%) or to the surface of the fiber of the polymer and crosslinking the polyvinyl alcohol polymer by reacting the epoxy compound with the hydroxyl group of the polyvinyl alcohol polymer by the aid of a basic catalyst such as sodium acetate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a polyvinyl alcohol (hereinafter, referred to as a "reinforcement") for general industrial materials such as fishing nets, ropes, tents, civil engineering sheets, etc., and cement, rubber, and plastic reinforcing materials which are required to have wet heat resistance and high strength. Abbreviated as PVA)
The present invention relates to a method for producing a synthetic fiber.

[0002]

2. Description of the Related Art Conventionally, PVA-based fibers have higher strength and strength than polyamide, polyester, and polyacrylonitrile-based fibers.
It has a high elastic modulus and is used as a fiber for industrial materials.
In addition, it is widely used as a reinforcing fiber of rubber, plastic, cement, etc.
Since the system fiber has the highest strength and high elasticity among general-purpose fibers, and has good adhesiveness and alkali resistance, it has been spotlighted as a cement reinforcing material instead of asbestos. However, PVA
The system fiber has poor moisture and heat resistance, and its use is limited even if it is used as a general industrial material or a garment material. Further, autoclaving at a high temperature, which is usually performed for a cement molded product, is impossible. Currently PV for cement reinforcement
When the A-based fiber is used, it is limited to a room temperature cured product, and therefore has the drawbacks that the dimensional stability and strength of the cement product are not sufficient and the curing days are long.

[0003] Attempts to improve the wet heat resistance of PVA-based fibers have been made for a long time. For example, by utilizing the acetalization reaction of a monoaldehyde compound such as formalin or a polyaldehyde compound such as glyoxal or glutaraldehyde with a hydroxyl group of PVA, PVA is used.
Many methods have been reported for improving the wet heat resistance of the A-based fiber by making the fiber hydrophobic or cross-linking. For example, in Japanese Patent Publication Nos. 30-7360 and 36-14565, formalin is used and PV
It is described that by formalizing the hydroxyl group of A to make it hydrophobic, a PVA-based fiber resistant to dyeing and washing can be obtained.

On the other hand, crosslinking with a dialdehyde compound is specified in Japanese Patent Publication No. 29-6145 and Japanese Patent Publication No. 32-5819, and Japanese Patent Application Laid-Open No. 163609/1993 discloses spinning of a dialdehyde or an acetal compound thereof. It describes that the fiber is applied to a yarn, stretched by dry heat at a high magnification, and then subjected to an acid treatment to cause crosslinking within the fiber. Further, Japanese Patent Application Laid-Open No. Hei 5-263331 (corresponding European Patent No. 5)
No. 20297, U.S. Pat. No. 5,380,588) discloses that the dry-heat drawn PVA fiber is added to the above-mentioned JP-A-5-163.
After infiltrating the inside of the fiber with the dialdehyde compound described in JP-A-609, immersion in a bath containing a monoaldehyde and a cross-linking catalyst to cause a cross-linking reaction, a PVA-based fiber excellent in hot water resistance is obtained, It is reported that this crosslinked PVA-based fiber is a fiber that can withstand autoclaving at 160 ° C.

[0005] By the way, the acetalization reaction between a monoaldehyde compound such as formalin, or a polyaldehyde compound such as glyoxal or glutaraldehyde, and a hydroxyl group of PVA has been reported.
In a method of improving the wet heat resistance of the A-based fiber by making the fiber hydrophobic or cross-linking, all the acetalization treatments are performed in an aqueous acid solution. However, it is clear from the study of the present inventors that this method requires a strong acid such as hydrochloric acid or sulfuric acid in order to allow the acetalization reaction to proceed sufficiently, and also requires that the temperature be 50 ° C. or higher. became. Treating under such conditions is nothing less than treating in a good solvent for PVA, and it is inevitable that the fibers swell during processing, and PVA itself partially dissolves. I was afraid. These phenomena have the effect of disturbing the molecular orientation of PVA or lowering the degree of crystallinity, and as a result, there has been a major problem in that the mechanical and mechanical strength inherent in PVA-based fibers is reduced.

[0006] The above-mentioned acid treatment step is usually performed after spinning. However, if the acid used for acetalization remains, P
Since it causes the coloration and the strength of the VA fiber to be reduced, a sufficient neutralization and washing step is actually required, and there is also a problem that the cost of the step is increased.

As a method other than the acetalization reaction using a monoaldehyde compound or a polyaldehyde compound, for example, a method of improving the wet heat resistance by dehydration crosslinking using an acid is disclosed in JP-A-2-84587 or JP-A-4-10091.
As is well known in Japanese Patent Publication No. 2 and other publications, when the present inventors performed an additional test, when trying to crosslink the inside of the fiber, the PVA fiber was severely decomposed, resulting in a significant decrease in fiber strength.

Also, Japanese Patent Application Laid-Open Nos. Hei 1-207435, Hei 2-133605, Hei 2-216288
In the publication, an acrylic acid-based polymer is blended or the fiber surface is coated with an organic peroxide or an isocyanate compound,
A method of crosslinking with a urethane compound, an epoxy compound or the like is described. However, since the cross-linking by the acrylic polymer is an ester bond, it is easily hydrolyzed by an alkali component in the cement to lose its effect, and the other cross-linking agents are basically cross-linked on the fiber surface. The fibers have problems such as swelling and dissolution from the center of the fiber when exposed to heat or during autoclave curing. It was enough performance. Particularly, the epoxy compound has low reactivity with the hydroxyl group of the PVA-based polymer.
The heat treatment described in Japanese Patent Application Publication No. 8 (1995) No. 8 is insufficient in the progress of cross-linking and therefore cannot be used under severe moist heat conditions such as high-temperature autoclave curing. Was.

[0009]

Under such circumstances, the present invention provides high strength, high elasticity, which is an original excellent property, even under severe high temperature and high humidity conditions such as high temperature autoclave curing.
Without impairing excellent adhesion and alkali resistance,
An object of the present invention is to provide a PVA-based fiber having high moist heat resistance without requiring complicated steps and a method for producing the same.

[0010]

In view of the above background, the present inventors have developed excellent properties such as high strength, high elasticity and excellent strength even under severe high temperature and high humidity conditions such as high temperature autoclave curing. As a result of intensive studies on a method for producing a PVA-based fiber having high moisture-heat resistance without impairing the adhesiveness and alkali resistance, polyvalent materials contained or adhered to the inside or surface of the fiber when producing the PVA-based fiber It has been found that a PVA-based fiber characterized in that an epoxy compound is reacted with a hydroxyl group of the PVA-based polymer by a base catalyst to cross-link the PVA-based polymer and a method for producing the same achieve the above objects, and the present invention It has been reached.

Hereinafter, the contents of the present invention will be described in more detail. The PVA-based polymer referred to in the present invention is obtained by saponifying polyvinyl acetate or a copolymer thereof, which is a usual method for producing polyvinyl alcohol. Also, by decomposition of homopolymer or copolymer of vinyl ether such as vinyl pivalate, vinyl ester having a bulky side chain such as vinyl formate or vinyl ester having high polarity, or vinyl ether such as t-butyl vinyl ether, trimethylsilyl vinyl ether or benzyl vinyl ether. can get.

Here, the comonomer unit in the case of the copolymer is divided into a unit which produces a vinyl alcohol unit by saponification or decomposition and a unit other than the unit. The latter comonomer unit is copolymerized mainly for the purpose of modification, and is used in a range that does not impair the purpose of the present invention. Examples of such a unit include olefins such as ethylene, propylene, 1-butene, and isobutene;
Acrylic acid and its salts, methyl acrylate, ethyl acrylate, n-propyl acrylate, i-propyl acrylate, n-butyl acrylate, i-butyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate, Acrylates such as dodecyl acrylate, octadecyl acrylate, methacrylic acid and salts thereof,
Methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, i-propyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, methacrylic acid Methacrylic esters such as dodecyl and octadecyl methacrylate, acrylamide, N-methylacrylamide, N-ethylacrylamide, N, N-dimethylacrylamide, diacetoneacrylamide, acrylamidepropanesulfonic acid and salts thereof, acrylamidopropyldimethylamine And its salts and quaternary salts,
Acrylamide derivatives such as N-methylolacrylamide and its derivatives, methacrylamide, N-methylmethacrylamide, N-ethylmethacrylamide, N, N
Methacrylamide derivatives such as dimethyl methacrylamide, diacetone methacrylamide, methacrylamidopropanesulfonic acid and salts thereof, methacrylamidopropyldimethylamine and salts thereof and quaternary salts, N-methylol methacrylamide and derivatives thereof, methyl vinyl ether, Ethyl vinyl ether, n-propyl vinyl ether, i-propyl vinyl ether, i-butyl vinyl ether, t-butyl vinyl ether, benzyl vinyl ether, dodecyl vinyl ether, vinyl ethers such as stearyl vinyl ether, acrylonitrile, nitriles such as methacrylonitrile, vinyl chloride,
Vinyl halides such as vinylidene chloride, vinyl fluoride and vinylidene fluoride; allyl compounds such as allyl acetate and allyl chloride; maleic acid and its salts and esters; itaconic acid and its salts and esters; vinylsilyl such as vinyltrimethoxysilane Compounds, isopropenyl acetate, etc.

The degree of saponification of the PVA polymer is preferably at least 70 mol%. In particular, when heat resistance, water resistance and oil resistance are required, the saponification degree is preferably 90 to 99.99 mol%. Here, the degree of saponification indicates the ratio of the vinyl alcohol unit after saponification to the unit that can be converted to a vinyl alcohol unit by saponification in a homopolymer or copolymer of vinyl acetate, and the residue is vinyl acetate. Is a unit.

[0014] The degree of polymerization of the PVA-based polymer also affects the performance of the fiber of the present invention. The higher the average degree of polymerization of the PVA-based polymer, the greater the number of tie molecules connecting the crystals, and the smaller the number of molecular terminals that become defects, so that high strength, high elastic modulus
High moisture-heat resistance is easily obtained, and therefore, it is preferably a PVA-based polymer having a polymerization degree of 1000 or more, and more preferably a PVA-based polymer having a polymerization degree of 1700 or more.
However, it is generally difficult to produce a PVA-based polymer having a degree of polymerization of more than 30,000, and is not necessarily suitable from the viewpoint of industrial production.

Examples of the solvent for the PVA-based polymer include polyhydric alcohols such as glycerin, ethylene glycol, diethylene glycol, triethylene glycol and butanediol, dimethyl sulfoxide, dimethylformamide, diethylene triamine, water, and a mixed solvent of two or more of these. Is mentioned. However, when the polyepoxy compound of the present invention is mixed and added to the solvent, a solvent that aggregates or separates the compound is not desirable,
Solvents that disperse or dissolve uniformly are preferred. Further, if the spinning solution has high acidity or alkalinity, the polyvalent epoxy compound may react with the PVA-based polymer in the stock solution, which is not preferable. In this respect, dimethyl sulfoxide and glycerin described above are preferable, and dimethyl sulfoxide is particularly preferable.

When the PVA-based polymer is dissolved in a solvent, boric acid, a surfactant, a decomposition inhibitor, a dye, a pigment, and the like may be added without any problem. It is not preferable to use an additive that causes the polyhydric epoxy compound to react with the PVA-based polymer in the stock solution, thereby deteriorating spinnability and stretchability. The concentration of the PVA-based polymer in the stock solution is preferably 5 to 50% by weight, particularly 5 to 20% by weight when using a wet spinning method or dry and wet spinning method, and 10 to 10% when using a dry spinning method. 50% by weight is preferred. The temperature of the spinning solution is 80-230 ° C.
Is common.

The spinning solution thus obtained is discharged from a nozzle and solidified by any of a wet method, a dry method, and a dry-wet method in a conventional manner. In wet and dry-wet spinning, the fibers are solidified in a coagulation bath to form fibers, and the coagulant may be any of alcohol, acetone, methyl ethyl ketone, and the like. However, when the polyepoxy compound used in the present invention is mixed and added to the spinning solution or the coagulation bath, the reaction between the polyepoxy compound and the PVA-based polymer proceeds simultaneously with the solidification of the spinning solution, and thereafter, It is not preferable to use an aqueous alkali solution, an aqueous alkali metal salt solution, or the like as a coagulation bath because the spinnability and the stretchability of the resin may deteriorate. In addition,
In order to form a uniform gel structure by slowing the solvent extraction in coagulation and to obtain higher strength and wet heat resistance, it is preferable to mix the coagulant with the solvent in an amount of 10% by weight or more.
Particularly, a mixed solution of an alcohol represented by methanol and a stock solution solvent is preferable. Further, rapid cooling at a solidification temperature of 20 ° C. or lower is also convenient for obtaining a uniform microcrystalline structure. In addition, in order to reduce sticking between fibers and facilitate subsequent dry heat drawing, it is preferable to perform 2 to 10 times wet drawing in a state containing a solvent. 20 to 6 as the wet stretching temperature
A range of 0 ° C. is preferred. Next, the fiber is immersed in an extraction bath to extract a solvent. As the extractant, alcohols such as methanol, ethanol, and propanol, acetone, methyl ethyl ketone, ether, and water can be used. Subsequently, the extractant is dried by applying an oil agent or the like as necessary. In the case of a dry method, the solvent is evaporated and dried at the time of spinning and after the spinning without using the extractant.

In order to exhibit the strength of the PVA-based fiber, the dried spun yarn is dry-heat drawn at 200 ° C. or higher, preferably 230 ° C. or higher, so that the total draw ratio is 13 times or higher, preferably 15 times or higher. . The stretching temperature is preferably increased as the degree of polymerization increases to maintain a high magnification.
It is not preferable because VA is easily decomposed. The total draw ratio is represented by the product of the wet draw ratio and the dry heat draw ratio.

A feature of the present invention is that when a PVA-based fiber is produced, a polyvalent epoxy compound contained or attached to the inside or surface of the fiber is reacted with a hydroxyl group of the PVA-based polymer by a base catalyst. This is to crosslink the PVA-based polymer.

Examples of the polyepoxy compound which can be used in the present invention include glycidyl ether type compounds synthesized from epichlorohydrin or methyl epichlorohydrin and a compound having two or more hydroxyl groups. For example, diglycidyl ether of bisphenol A, polyglycidyl ether, ethylene glycol diglycidyl obtained by the reaction of a novolak-type phenolic condensate obtained by condensation of a phenolic compound such as phenol or cresol with formaldehyde and shrimp chlorohydrin Ether, propylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, neopentyl glycol diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, polyglycerin diglycidyl ether, polyglycerin triglycidyl ether, poly Glycerin tetraglycidyl ether, trimethylolpropane triglycidyl And the like ether.

Further, there may be mentioned glycidyl ester type compounds synthesized from epichlorohydrin or methyl epichlorohydrin and a compound having two or more carboxyl groups or an acid anhydride thereof. For example, diglycidyl esters of aromatic dibasic acids such as phthalic acid, isophthalic acid, terephthalic acid, tetrahydrophthalic acid and hexahydrophthalic acid, diglycidyl esters of aliphatic dibasic acids such as succinic acid and adipic acid, dimers Diglycidyl esters of acids (dicarboxylic acids having an average of 36 carbon atoms), esters obtained by the reaction of acid anhydrides such as phthalic anhydride, maleic anhydride, trimellitic anhydride, and pyromellitic anhydride with epichlorohydrin, etc. It is.

Glycidylamine type compounds synthesized from epichlorohydrin or methyl epichlorohydrin and a compound having at least one amide group can also be mentioned. For example, it is a compound obtained by reacting aniline, bis (p-aminodiphenyl) methane, aminotoluene and the like with epichlorohydrin. Also, polybutadiene di-, tri-, or tetraepoxides,
Di-, tri-, or tetra-epoxidized (poly) dicyclopentadiene and di-, tri-, or tetra-epoxidized (poly) norbornene or (poly) norbornene derivatives can also be used in the present invention. These polyepoxy compounds can be used alone or in combination of two or more.

Among these, considering the affinity and reactivity with the PVA-based polymer, the versatility when used industrially, and the solubility and dispersibility in a solvent, the polyvalent epoxy compound to be used is from 2 to 4. Compounds having four epoxy groups are preferred. A specific example is a glycidyl ether type synthesized from epichlorohydrin or methyl epichlorohydrin and a compound having 2 to 4 hydroxyl groups. For example, diglycidyl ether of bisphenol A, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, neopentyl glycol diglycidyl ether, trimethylolpropane triglycidyl ether, polyethylene glycol diglycidyl ether , Polypropylene glycol diglycidyl ether, polyglycerin diglycidyl ether, polyglycerin triglycidyl ether, polyglycerin tetraglycidyl ether and the like. Further, a glycidyl ester type compound synthesized from epichlorohydrin or methyl epichlorohydrin and a compound having 2 to 4 carboxyl groups or an acid anhydride thereof can be mentioned. For example, diglycidyl esters of aromatic dibasic acids such as phthalic acid, isophthalic acid, terephthalic acid, tetrahydrophthalic acid, and hexahydrophthalic acid, diglycidyl esters of aliphatic dibasic acids such as succinic acid and adipic acid, and dimers Acid (with an average carbon number of 36
Dicarboxylic acid), esters obtained by reaction of acid anhydrides such as phthalic anhydride, maleic anhydride, trimellitic anhydride, and pyromellitic anhydride with epichlorohydrin. Also, di-, tri- or tetra-epoxidized polybutadiene, di-, tri- or tetra-epoxidized (poly) dicyclopentadiene, (poly) norbornene or (poly)
Di, tri, or tetraepoxides of norbornene derivatives can also be used in the present invention. Further, in consideration of stability under severe high temperature and high humidity conditions such as high temperature autoclave curing, a glycidyl ether type divalent to tetravalent epoxy compound is preferable.

The application of the polyvalent epoxy compound used in the present invention may be carried out in any step of extraction from the spinning dope. Specifically, a method of dissolving or dispersing the compound in the spinning dope and including it in the PVA, dissolving or dispersing the compound in alcohol or ketones in a coagulation bath,
A method of solidifying the fiber into a PVA when the spinning stock solution is solidified into a fiber; dissolving the compound in alcohol or ketones in an extraction bath and passing the swollen yarn into the fiber to convert the compound into a fiber; Examples of such a method include a method of sufficiently containing the compound in the interior. Among them, a method of dissolving the compound in alcohol or ketones of the extraction bath and passing the swollen yarn into the compound to sufficiently contain the compound inside the fiber,
The compound is preferable in that the compound can be uniformly and sufficiently contained in the fiber, and the amount can be easily controlled. In this case, the temperature of the bath containing the polyepoxy compound is preferably -10 to + 50 ° C, and the concentration of the compound in the bath is preferably 0.01 to 1 mol / liter. The immersion time of the fiber in the bath is preferably 5 seconds or more, and if the immersion time is less than 5 seconds, the amount of the compound adhering to the fiber may be insufficient and sufficient hot water resistance may not be obtained.

In the present invention, the content or amount of the polyvalent epoxy compound is preferably 0.05 to 20 mol% based on the repeating structural units of the PVA-based polymer.
More preferably, it is 0.1 to 10 mol%. If the amount of adhesion is less than 0.05 mol%, the cross-linking density is low, so that the wet heat resistance is insufficient. If it exceeds 20 mol%, the molecular orientation is disturbed and the decomposition of PVA is accelerated, and the strength is liable to be reduced. The amount of adhesion can be controlled by changing the content of the polyvalent epoxy compound in the bath containing the compound.

Next, the base catalyst used in the present invention is not particularly limited as long as the polyepoxy compound has sufficient basicity to react with the hydroxyl group of PVA.

Among these, considering the strength of basicity, versatility in industrial use, and solubility and dispersibility in solvents, metal salts of aliphatic, alicyclic or aromatic carboxylic acids are considered. Is preferred. Specific examples of aliphatic or aromatic carboxylic acids include formic acid, acetic acid, maleic acid, benzoic acid, phthalic acid and the like, and specific examples of metals include ytterbium,
Yttrium, potassium, calcium, silver, cobalt,
Examples include samarium, zirconium, tin, thallium, copper, sodium, lead, nickel, palladium, barium, magnesium, manganese, lanthanum, lithium, and rhodium. Of these, acetate is particularly preferred.Specifically, ytterbium acetate, yttrium acetate, potassium acetate, calcium acetate, silver acetate, cobalt acetate, samarium acetate, zirconium acetate, tin acetate, thallium acetate, copper acetate, sodium acetate, acetic acid Lead, nickel acetate,
Examples include palladium acetate, barium acetate, magnesium acetate, manganese acetate, lanthanum acetate, lithium acetate, rhodium acetate, and the like, with sodium acetate being particularly preferred.

By bringing these base catalysts into contact with the polyvalent epoxy compound adhered or contained in or on the PVA-based fiber, the reaction between the fiber and the polyvalent epoxy compound proceeds. For example, when ethylene glycol diglycidyl ether is used as the polyvalent epoxy compound, a base is used as a catalyst.

It is considered that the fiber reacts with the hydroxyl group of the PVA-based polymer as shown in the following formula, and as a result, the fiber is crosslinked. At this time, the reaction rate between the epoxy group in the polyvalent epoxy compound and the hydroxyl group of the PVA-based polymer is preferably 60% or more in order to provide the PVA-based fiber with the required wet heat resistance.
It is more preferably at least 75%, further preferably at least 80%. It is considered that the unreacted epoxy group remains in the fiber as it is or reacts with moisture or the like in the PVA-based fiber to be converted to alcohol.

[0029]

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The contact between the base catalyst and the polyepoxy compound may be carried out in any step after the dry spinning from the stock spinning solution, as long as the reaction proceeds efficiently. Specifically, a method of dissolving or dispersing a base catalyst in a spinning stock solution and incorporating it into the PVA-based fiber, a method of dissolving or dispersing the base catalyst in an extraction bath, A method of applying a base catalyst dissolved or dispersed in a solvent or water, or the like, may be used.

In the case where the basic catalyst used is strongly basic and the reaction proceeds instantaneously upon contact with the polyvalent epoxy compound, the polyvalent epoxy compound is once converted to PVA.
After being uniformly contained in the system fiber, it is preferable that the polyhydric epoxy compound and the base catalyst are brought into contact with each other and reacted after drying and drawing steps. After dissolving the polyvalent epoxy compound and allowing the swollen yarn to pass through it, the compound is sufficiently contained inside the fiber, dried and drawn, and then dissolved in a suitable solvent or water on the fiber surface. Alternatively, a method of applying a dispersed base catalyst may be used.

In the above-mentioned method of applying the base catalyst to the fiber surface after drying and drawing, a sufficient amount of the catalyst to react the hydroxyl group of the PVA polymer with the polyepoxy compound in the fiber reaches the inside of the fiber. When it is difficult to infiltrate, the following method is preferable. That is, a reaction with a hydroxyl group of PVA is first performed by using a catalyst having a weak basicity such that the reaction does not proceed at a temperature of about room temperature and performing an appropriate heat treatment to improve the reactivity of the polyvalent epoxy compound. Is selected, and the polyhydric epoxy compound and the base catalyst are simultaneously dissolved or dispersed in an alcohol or ketone in an extraction bath, and the compound is passed through the swollen yarn therein. After sufficient incorporation into the fiber, a drying and drawing step, and then a heat treatment step at an appropriate temperature, or a simultaneous crosslinking step in the fiber drying and drawing steps can be performed.

Although the content of the base catalyst in the obtained fiber varies depending on the kind, in the case of the metal salt of the aliphatic or aromatic carboxylic acid, the content of the metal catalyst is not more than 200 in terms of the metal element relative to the PVA polymer.
6000 ppm is preferred. When the amount is less than 200 ppm, the reaction between the polyvalent epoxy compound in the PVA-based polymer and the hydroxyl group does not sufficiently proceed, so that the effect of expressing wet heat resistance is small. When the amount exceeds 6000 ppm, the mechanical mechanical strength of the fiber finally obtained. This is not preferred because it may decrease the color and promote the coloring and decomposition. The content when two or more types of the base catalysts are used means the total amount.

The single fiber strength of the fiber obtained by the present invention is preferably 8 g / d or more, more preferably 10 g / d.
d or more. When the single fiber strength is less than 8 g / d, the effectiveness as a reinforcing material for general industrial materials such as fishnets, ropes, tents, civil engineering sheets and the like, cement, rubber, and plastic, which are required to have wet heat resistance and high strength, In particular, it is difficult to use as a reinforcing material for cement products that undergo autoclaving.

[0035]

EXAMPLES The present invention will be described below in detail with reference to examples, but the present invention is not limited to the examples.
The various physical property values in the present invention are defined by the following methods. 1) Viscosity average degree of polymerization PA of PVA The specific viscosity ηSP of the PVA dilute aqueous solution at 30 ° C. was measured at 5 points based on JIS K-6726, and the intrinsic viscosity [η] was obtained from the following equation (1). ) Was used to calculate the viscosity average degree of polymerization PA. [Η] = lim (C → O) ηSP / C (1) PA = ([η] × 10 ⁴ /8.29) ^1.613 (2)

2) Amount of polyepoxy compound in PVA-based fiber The polyepoxy compound-containing fiber after drying is mixed with 50 to 140
NMR in dimethyl sulfoxide at ℃
To calculate the peak area ratio of the epoxy to the CH2 group peak of PVA, and the content was determined from a previously prepared calibration curve.

3) Content of base in PVA-based fiber The metal salt of carboxylic acid used as the base catalyst is obtained by dissolving the yarn before the dry heat drawing treatment in dimethyl sulfoxide at 100 to 130 ° C. Element peaks were measured and determined from a calibration curve.

4) Tensile strength of single fiber According to JIS L-1015, a previously conditioned single fiber is stuck on a backing paper so as to have a test length of 10 cm at 25 ° C. × 60% R.
Leave at H for 12 hours or more. Next, using an Instron 1122 using a chuck for 2 kg, the breaking strength was determined at an initial load of 1/20 g / d and a tensile speed of 50% / min, and the average value of n ≧ 10 was adopted. Denier is 30 under 1/10 g / d load
It was cut to a cm length and determined by the weight method. In addition, the strength and elongation and the elastic modulus were measured using the single fiber after the denier measurement, and each fiber was made to correspond to the denier.

5) Elution amount of fiber in hot water About 100 milligrams of the finally obtained PVA-based fiber was
After being cut into mm, the mixture was precisely evaluated in a test tube, 10 ml of distilled water was added, the tube was sealed, and heat treatment was performed in an autoclave (manufactured by Yamato Scientific Co., SP22) (121 ° C. × 2 hours).
did. The PVA-based fiber in the test tube was separated by filtration, washed with distilled water, dried and dried (120 ° C. × 10 hours or more), and the dissolution rate was determined.

Examples 1 to 11 The viscosity average degree of polymerization was 2400 and the degree of saponification was 99.5 mol%.
Of PVA was dissolved in dimethyl sulfoxide (DMSO) at 100 ° C. so as to have a concentration of 20% by weight, and the resulting solution was discharged from a 400-hole nozzle, and methanol / D
The wet spinning was performed in a coagulation bath at 5 ° C. with a weight ratio of MSO = 7/3.
After further stretching 3.5 times in a 40 ° C. methanol bath,
All of the dimethyl sulfoxide was removed by sequentially passing the fibers through a two-stage methanol extraction bath. In the final methanol extraction bath, ethylene glycol diglycidyl ether was added as a polyepoxy compound at a rate of 0.2 mol / mol to the bath.
Liter, the base catalyst shown in Table 1 was added to the bath in an amount of 400 ppm in terms of a metal element to make a uniform solution. After that, the fiber was retained for 1.5 minutes to leave the polyepoxy compound inside and on the surface of the methanol-containing fiber. And a base catalyst, then dried at 120 ° C. The obtained spun yarn is stretched in a hot-air furnace consisting of three sections at 175 ° C., 195 ° C. and 230 ° C. so as to have a total draw ratio of 15.5, and further subjected to a constant-length heat treatment at 250 ° C. for 50 seconds. Was. The single fiber denier of the obtained fiber was 3.0 dr. Table 1 shows the fiber properties finally obtained.

Examples 12 to 16 In the final methanol extraction bath, as a polyvalent epoxy compound,
Bisphenol A diglycidyl ether (Example 12), trimethylolpropane triglycidyl ether (Example 13), glycerin diglycidyl ether (Example 14), polyethylene glycol diglycidyl ether (Example 15), polypropylene glycol diglycidyl ether, respectively (Example 16) 0.2
Spinning, drawing and heat treatment were performed in the same manner as in Example 1 except that mol / liter was added. Table 1 shows the fiber properties finally obtained.

Comparative Example 1 Spinning, stretching and heat treatment were carried out in the same manner as in Examples 1 to 16, except that the polyhydric epoxy compound and the base catalyst were not added to the final methanol extraction bath. Table 1 shows the fiber properties finally obtained.

Comparative Example 2 Spinning, drawing and heat treatment were carried out in the same manner as in Example 1 except that the polyhydric epoxy compound was not added to the last methanol extraction bath. Table 1 shows the fiber properties finally obtained.

Comparative Example 3 Spinning, drawing and heat treatment were performed in the same manner as in Example 1 except that no base catalyst was added to the final methanol extraction bath. Table 1 shows the fiber properties finally obtained.

[0045]

[Table 1]

Examples 17 to 20 The same procedure as in Example 1 was carried out except that ethylene glycol diglycidyl ether as a polyepoxy compound was added to the final methanol extraction bath at a concentration as shown in Table 2 with respect to the bath. Spinning, drawing, and heat treatment were performed by the method. Table 2 shows the fiber properties finally obtained.

[0047]

[Table 2]

Examples 21 to 22 The same procedure as in Example 1 except that sodium acetate was added as a base catalyst to the final methanol extraction bath at a concentration as shown in Table 3 in terms of metal element. And spinning,
Stretching and heat treatment were performed. Table 3 shows the fiber properties finally obtained.

[0049]

[Table 3]

[0050]

According to the present invention, even under severe high temperature and high humidity conditions such as high temperature autoclave curing, the original excellent properties of high strength, high elasticity, excellent adhesion and alkali resistance are not impaired, and PVA-based fibers having high wet heat resistance can be obtained without requiring complicated steps,
It can be used not only for general industrial materials such as ropes, fishing nets, tents, and civil engineering sheets, but also for a wide range of applications such as cement reinforcements that can be autoclaved at high temperatures.

Claims (1)

[Claims] When producing a fiber comprising a polyvinyl alcohol-based polymer, the polyvinyl alcohol-based polymer is contained or adhered to the interior or the fiber surface of the polyvinyl alcohol-based polymer by a base catalyst. A method for producing a polyvinyl alcohol-based synthetic fiber, characterized in that the polyvinyl alcohol-based synthetic fiber is crosslinked by reacting with a hydroxyl group having the polymer.