JPH10280228A - Production of spinning dope and production of fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a spinning dope having excellent spinnability, and further to provide a method for producing a fiber free from its breakage, etc., in a high productivity. SOLUTION: A spinning dope is produced by thermally dissolving a polyvinyl alcohol-based polymer having an isotacticity content of >=72% expressed by triad and having an intrinsic viscosity of >=0.7 dl/g in a solvent consisting mainly of dimethyl sulfoxide, water or their mixture at a temperature of 100-180 deg.C and subsequently controlling the solution into a concentration of 3-25 wt.%. The intrinsic viscosity is measured in acetone at 30 deg.C in the form of polyvinyl acetate obtained by acetylating the polyvinyl alcohol. And a fiber is produced using the spinning dope.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a spinning dope having excellent spinnability, and a high productivity, heat-resistant, water-, moist-heat-resistant and durable material which is free from thread breakage using the spinning dope. The present invention relates to a method for producing a fiber comprising a polyvinyl alcohol-based polymer having excellent properties.

[0002]

2. Description of the Related Art Conventional polyvinyl alcohol fibers are superior to polyamide, polyester and polyacrylonitrile fibers in mechanical properties, weather resistance and chemical resistance. Applications have been pioneered. Recently, it has been attracting attention as a fiber for cement reinforcement (alternative to asbestos fiber) that utilizes the characteristics of alkali resistance, and is expected to be a high-performance, high-performance fiber that combines high strength, high elastic modulus and high heat resistance. Development is urgent.

Incidentally, the stereoregularity of a polyvinyl alcohol-based polymer which is a raw material polymer of a polyvinyl alcohol-based fiber which is currently commercially available is close to atactic (the isotacticity content by triad display is about 22%). is there. Tacticity in the present invention is a value obtained by 1H-NMR measurement of a DMSO-d6 solution of polyvinyl alcohol shown below. DMSO-
It is known that the resonance absorption of the proton of the hydroxyl group of the polyvinyl alcohol-based polymer in d6 is separated into three peaks belonging to isotactic, heterotactic and syndiotactic, respectively, in triad representation from the low magnetic field side. The tacticity of polyvinyl alcohol can be quantified from the integration ratio of each peak.
Here, the chemical shift of each beak is shifted according to the measurement temperature. The chemical shift of each peak at the measurement temperature of 35 ° C. is 463 ppm for isotactic, 445 ppm for heterotactic, and 422 ppm for syndiotactic, respectively (J. R. DeMember, H .;
C. Haas, and R.A. L. MacDonald,
J. Polym. Sci. , Part B, 10, 38
5 (1972)). Hereinafter, unless otherwise specified, the polyvinyl alcohol tacticity is the tacticity of the triad display measured by this method.

[0004] As a conventional isotactic polyvinyl alcohol, a report by Okamura et al. (S. Okura,
T. Kodama, T .; Higashimura, Ma
cromol. Chem. , 53, 180 (196)
2) DMS of polyvinyl alcohol obtained according to)
It has been reported that the isotacticity content of the O-d6 solution determined by 1H-NMR measurement is 55% in triad notation (JR DeMember, HCCH).
aas, and R.A. L. MacDonald, J.M. P
olym. Sci. , Part B, 10, 385 (1
972).

Further, a report by Murahashi et al. (S. Murahas)
hi, S. Nozakura, M .; Sumi, J .; Po
lym. Sci. , Part B, 3, 245 (196
5)) The isotacticity content of the DMSO-d6 solution of the polyvinyl alcohol-based polymer obtained according to 1) determined by 1H-NMR measurement is 70.2 as a triad.
% Of polyvinyl alcohol is reported (TKW).
u, D. W. Ovenall, Macromolecu
les, 6, 582 (1973). However, at present, polyvinyl alcohol having an isotacticity content higher than that has not been obtained.

The fiber obtained from the polyvinyl alcohol-based polymer having an isotacticity content of 55% obtained by the above method is compared with the fiber obtained from a polyvinyl alcohol-based polymer having an isotacticity content of 22%. As the heat resistance decreases, the crystallinity and the melting temperature decrease, and the water resistance such as solubility in warm water also decreases. In the case of fibers obtained from a polyvinyl alcohol-based polymer having an isotacticity of 70.2%, the melting temperature is increased as compared with fibers obtained from a polyvinyl alcohol-based polymer having an isotacticity of 55%. However, it is not satisfactory in terms of melting point, crystallinity, water resistance, heat resistance and the like.

The present inventors have reported in JP-A-5-1107 a polyvinyl alcohol having an extremely high isotacticity, and exemplify high-strength fibers, water-resistant fibers and heat-resistant fibers as uses thereof. Among them, the physical properties of the film are exemplified as examples, and the film at this time is made of an aqueous solution of polyvinyl alcohol having a very low concentration of 2% by weight. However, when fibers are prepared from such a low-concentration polymer solution, in many cases, the spun yarn is easily broken, so that fiberization is practically impossible. Alternatively, there is a problem that the productivity is extremely low and the product cannot be used industrially.

[0008]

Under these circumstances, the present invention provides water resistance and heat resistance while maintaining the excellent properties of conventional isotactic polyvinyl alcohol-based polymer fibers such as stretchability and processing properties. And various other physical properties are conventionally available with an isotactic content of 2
An object of the present invention is to provide a method for producing a spinning dope for obtaining a polyvinyl alcohol-based polymer fiber which is extremely excellent as compared with a 2% polyvinyl alcohol-based polymer fiber, and a method for producing a fiber using the spinning dope.

[0009]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that the isotacticity content is 72% or more in triad notation, and that the polyvinyl acetate obtained by acetylation in acetone A polyvinyl alcohol polymer having an intrinsic viscosity of 0.7 dl / g or more at 30 ° C. is dissolved by heating at a temperature of 100 ° C. or more and 160 ° C. or less in a solvent containing dimethyl sulfoxide, water, or a mixed solution thereof as a main component. It has been found that the above object can be achieved by using a spinning dope obtained by adjusting the concentration to 3% by weight or more and 25% by weight or less, thereby completing the present invention.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
The polyvinyl alcohol-based polymer used for the fiber of the present invention is a polyvinyl alcohol-based polymer mainly containing vinyl alcohol units. Increasing the isotactic content is effective in improving water resistance and heat resistance. To achieve the effects of the present invention, isotacticity must be 7%.
It is necessary to make it 2% or more, preferably 75% or more, more preferably 78% or more. The upper limit of the isotacticity is not particularly limited, but is appropriately selected from 95% or less, 90% or less, 85% or less, or 80% or less depending on the use in which the polymer is used.

The polyvinyl alcohol polymer used for the fiber of the present invention may be a vinyl ester such as vinyl acetate, vinyl pivalate or vinyl formate, or a homopolymer of vinyl ether such as t-butyl vinyl ether, trimethylsilyl vinyl ether or benzyl vinyl ether. It is obtained by saponification or decomposition of a copolymer.

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 within a range not to 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,
Acrylates such as i-propyl acrylate, n-butyl acrylate, i-butyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate, 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 its salts, acrylamidopropyldimethylamine and its salts and quaternary salts, N-methylolacrylamide and its derivatives, etc. Acrylamide derivative, methacrylamide, N-methylmethacrylamide, N-ethylmethacrylamide, N, N-dimethylmethacrylamide, diacetone methacrylamide, methacrylamidopropanesulfonic acid and salts thereof, methacrylamidopropyldimethylamine and salts thereof And quaternary salts, methacrylamide derivatives such as N-methylol methacrylamide and derivatives thereof, methyl vinyl ether, ethyl vinyl ether, n
Vinyl ethers such as -propyl vinyl ether, i-propyl vinyl ether, i-butyl vinyl ether, t-butyl vinyl ether, benzyl vinyl ether, dodecyl vinyl ether, stearyl vinyl ether, trimethylsilyl vinyl ether, diethylmethylsilyl vinyl ether, and dimethylethylsilyl vinyl ether; acrylonitrile, methacryloyl Nitriles such as nitriles, vinyl chloride, vinylidene chloride, vinyl fluoride,
Vinyl halides such as vinylidene fluoride, allyl acetate, allyl compounds such as allyl chloride, maleic acid and its salts and esters, itaconic acid and its salts and esters,
Vinylsilyl compounds such as vinyltrimethoxysilane; isopropenyl acetate;

The degree of saponification of the polyvinyl alcohol-based polymer is usually preferably at least 70 mol%. In particular, the degree of saponification is 9 when heat resistance, water resistance, wet heat resistance, and oil resistance are required.
0 to 99.99 mol% is preferable. Here, the degree of saponification represents the ratio of the vinyl alcohol unit after saponification or decomposition to the unit that can be converted into a vinyl alcohol unit by saponification or decomposition in a homopolymer or copolymer of vinyl esters or vinyl ethers. It is.

The degree of polymerization of the polyvinyl alcohol polymer also affects the performance of the fiber of the present invention. The degree of polymerization is expressed by a limiting viscosity value of polyvinyl acetate obtained by acetylating a vinyl alcohol portion of the polymer measured at 30 ° C. in acetone. Although the degree of polymerization is appropriately selected depending on the use of the fiber, in view of strength and processing characteristics, the intrinsic viscosity of polyvinyl acetate is 0.7 dl / g or more, preferably 0.85 dl.
/ G or more, more preferably 1.0 dl / g or more.
On the other hand, increasing the degree of polymerization is a preferred direction from the viewpoint of stretchability and the like, but also tends to cause a decrease in solubility in a solvent and spinnability, and the upper limit of the intrinsic viscosity is preferably 15 dl /.
g, and is appropriately selected from 10 dl / g or less, 7 dl / g or less, or 5 dl / g or less depending on the use in which the fiber is used.

The method for obtaining the polyvinyl alcohol-based polymer used in the fiber of the present invention is not particularly limited, but one example is shown below. Using t-butyl vinyl ether as a monomer, toluene as a non-polar solvent as a solvent, and a cationic trifluoroboron ether complex as a polymerization initiator at a concentration of 0.1 to 0.5 mmol / l.
The polymerization is carried out at a temperature of -78 ° C or less, and the obtained polyvinyl ether is obtained by bubbling hydrogen bromide at a temperature of 0 ° C or less in a solvent such as toluene.

The polyvinyl alcohol-based fiber of the present invention comprises:
It is obtained by spinning a polyvinyl alcohol-based polymer having an isotactic content of 72% or more as indicated by a triad as described above. Conventionally, when producing a polyvinyl alcohol-based polymer fiber having an isotacticity of 22%, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, ethylene glycol, glycerin, water, and hexafluorofluoroethylene are used as a solvent for the spinning solution. Isopropanol or the like is used alone or in combination. However, the isotacticity used in the present invention is 72% or more, and the intrinsic viscosity of acetone obtained at 30 ° C. in acetone of polyvinyl acetate is 0.3%.
A polyvinyl alcohol polymer having a dl / g of 7 dl / g or more has an isotacticity having a similar degree of polymerization of 22%.
It has been found by our investigation that the solubility in various solvents is lower than that of the polyvinyl alcohol-based polymer of the present invention. This is considered to be due to the high crystallinity and water resistance characteristic of the polyvinyl alcohol-based polymer having an isotacticity of 72% or more. That is, since the polyvinyl alcohol-based polymer used in the present invention has a higher isotacticity content than the conventional isotactic polyvinyl alcohol-based polymer, it has a different crystal structure from the conventional polyvinyl alcohol-based polymer. And
As a result, it is considered that the cause is that they exhibit extremely different physical properties such as high crystallinity and high melting point. Based on the above background, as a result of examining the solubility of the polyvinyl alcohol-based polymer in various solvents, dimethyl sulfoxide, water, or dimethyl sulfoxide and water were found to be solvents having sufficient solubility to produce fibers. Was found to be suitable.

The composition of the mixed solution of dimethyl sulfoxide and water used as a solvent is not particularly limited, and the dimethyl sulfoxide content is 0 to 100% by weight, and the water content is 100%.
The solubility of the polyvinyl alcohol-based polymer used in the present invention is higher than that of dimethyl sulfoxide.
The dimethylsulfoxide content is 50 to 100% by weight, the water content is 50 to 0% by weight, more preferably the dimethylsulfoxide content is 75 to 100% by weight, and the water content is 25 to 0%.
Weight percent. In addition, inorganic salts such as lithium chloride and calcium chloride, and other organic solvents such as glycerin and ethylene glycol can be mixed as long as the solubility of the polyvinyl alcohol-based polymer used in the present invention is not impaired. Further, when dissolving the polyvinyl alcohol-based polymer with a solvent, addition of boric acid, a surfactant, a decomposition inhibitor, a dye, a pigment, or the like does not cause any problem, but those which deteriorate spinnability and stretchability are not preferred.

Although the concentration of the polyvinyl alcohol-based polymer in the spinning solution varies depending on the spinning method, it is substantially difficult to obtain a high-concentration solution for the above-mentioned reasons, and the concentration is 3 to 25.
It is important that the weight percent be used. Particularly preferably 4 to 2
0% by weight. Further, for the same reason, even if a solvent having excellent solubility is used, it is substantially difficult to prepare a solution having a concentration necessary for preparing fibers under conditions such as room temperature. The dissolution temperature is 100 ° C
It is important that this is the case. Here, the upper limit of the temperature is not particularly limited, but is preferably 180 ° C., and if the temperature is higher than that, the solvent or the polyvinyl alcohol-based polymer may be decomposed or colored, which is not preferable. A particularly preferred dissolution temperature is 105-160 ° C. Also,
The dissolution step in preparing the solution is usually performed in air or in an inert gas such as nitrogen gas.In order to suppress the decomposition or coloring of the solvent or the polyvinyl alcohol-based polymer, an inert gas such as nitrogen gas is used. Preferably, it is performed in a gas. The spinning dope prepared in this manner has excellent spinnability, and when fibers are produced using this spinning dope, there is no thread breakage and the productivity is high.

The spinning dope thus obtained is wet-processed,
It is discharged from the nozzle and solidified by either a dry method or a dry-wet method. In the wet and dry-wet spinning, the fibers are solidified in a coagulation bath to form fibers. The coagulant may be any of alcohol, acetone, methyl ethyl ketone, an aqueous alkali solution, and an aqueous alkali metal salt solution. In order to form a uniform 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 2% by weight or more. Particularly, a mixed solution of an alcohol represented by methanol or ketones represented by acetone and a stock solution solvent is preferable. In addition, the solidification temperature is 20 ° C
The following rapid cooling is also convenient for obtaining a uniform structure. Further, in order to reduce sticking between fibers and facilitate subsequent dry heat drawing, it is preferable to perform wet drawing by a factor of 2 to 10 in a state containing a solvent. The wet stretching temperature is 20
To 60 ° C. In the case of alkali coagulation, it is preferable to perform neutralization under tension before wet stretching. 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 develop the strength of the polyvinyl alcohol-based polymer fiber, the dried spun yarn is dry-heat drawn at 200 ° C. or higher, preferably 220 ° C. or higher, so that the total draw ratio is at least 10 times or higher. This stretching operation is performed in the air, in an inert gas such as nitrogen gas, or in an oil bath,
It is performed in one or two or more stages. Further, a so-called zone stretching method of heating and stretching in a minute area can also be applied. It is preferable that the stretching temperature is increased as the degree of polymerization increases and the high magnification is maintained. The total draw ratio is represented by the product of the wet draw ratio and the dry heat draw ratio. In addition, the single fiber fineness of the fiber in the present invention is not particularly limited, and is appropriately selected in a range of 0.5 dr to 20 dr depending on the use in which the fiber is used.

In the fiberization of the polyvinyl alcohol-based polymer of the present invention having an isotacticity of 72% or more as indicated by a triad, a fiber other than the above-mentioned polyvinyl alcohol-based polymer is used as long as the purpose of the present invention is not impaired. May be contained at all, and examples thereof include ordinary polyvinyl alcohol polymers and other polymers, plasticizers such as glycerin, surfactants, and inorganic compounds such as clay, silica, and calcium carbonate.
If necessary, dyes and pigments for coloring, and stabilizers such as antioxidants and ultraviolet absorbers may be added.

[0023]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the present invention. The various physical property values in the present invention are defined by the following methods. 1) Mechanical properties Autograph (model: AG-5000) manufactured by Shimadzu Corporation
B), using a fiber length of 10 cm and a pulling speed of 10 cm /
The strength, elongation and initial elastic modulus of the single yarn at 20 ° C. and 65% RH were measured under the conditions of min.

2) Melting point The melting point was measured with a cut length of about 1 mm.
About 10mg of fiber sample of Mettler
Using a C measuring device (Mettler DSC30), the peak temperature of the melting curve when the temperature was raised at a rate of 10 ° C./min was taken as the melting point.

3) Hot water resistance Using a simple chemical reaction device (model TEM-V) manufactured by Taiatsu Nikko Kogyo Co., Ltd., test length 4 cm
A load of 2 mg / denier on the fibers of 1.5 ° C
Fusing temperature in hot water at a heating rate of
WTb).

Example 1 A glass container equipped with a stirrer was prepared, and degassing under reduced pressure under heating with nitrogen gas was repeated to replace the system with nitrogen.
0.07 trifluoroboron ether complex (BF3.O (Et) 2; manufactured by Wako Pure Chemical Industries, Ltd.) as an initiator in a container
2300 ml of dehydrated and distilled toluene in which 4 ml had been dissolved was added, and the mixture was cooled in a dry ice / acetone cooling bath. When the temperature in the system reached −78 ° C., 120 ml of dehydrated and distilled t-butyl vinyl ether monomer was poured to initiate polymerization. After 3 hours and 30 minutes, 240 ml of methanol was added to the system.
Was added to stop the polymerization, the content was poured into a large amount of methanol, and the produced polymer was recovered, followed by drying at 60 ° C. under reduced pressure. The obtained polymer was 81.8 g, and the yield was 85.8 g.
2%. Next, 40 g of this polymer was dissolved in 5000 ml of toluene, and thoroughly stirred while blowing hydrogen bromide gas in an ice bath at 0 ° C. About 3 minutes after the start of the reaction, the produced polyvinyl alcohol was precipitated and the inside of the system became cloudy. After blowing hydrogen bromide gas for further 7 minutes, the precipitated polymer was separated by filtration, neutralized with ammoniacal methanol and methanol, and subjected to Soxhlet washing with methanol to obtain polyvinyl alcohol. The obtained polyvinyl alcohol was dissolved in DMSO-d6, and 1H-
NMR measurement revealed that the content of the polyvinyl alcohol unit was 99.9 mol% or more and the isotacticity content was 78.8.
%Met. The intrinsic viscosity of the polyvinyl acetate obtained by acetylating the polyvinyl alcohol measured at 30 ° C. in acetone was 1.89 dl / g. This polyvinyl alcohol-based polymer is converted into dimethyl sulfoxide (hereinafter, referred to as dimethyl sulfoxide).
Dissolved at 110 ° C. in DMSO).
A 2% by weight solution was prepared. The solution was used as a spinning solution, and dry-wet spinning was performed using a single hole having a hole diameter of 0.2 mmφ as a die with a gap of 2.5 cm from a coagulation bath of methanol.
The obtained spun yarn is thoroughly washed in methanol,
Drying was done under reduced pressure at ℃. The dried yarn was drawn 14 times in an electric furnace having air at 250 ° C. The single yarn fineness of the obtained drawn yarn is 5.3 d, the single yarn strength is 10.6 g / d, the initial elastic modulus is 280 g / d, the elongation is 10.5%, and the melting point is 255.
° C and WTb were 138 ° C. Also, there was no occurrence of thread breakage, indicating high productivity.

Comparative Example 1 A report by Okamura et al. (S. Okamura, T. Kodam)
a, T .; Higashimura, Macromol.
Chem. , 53, 180 (1962)) was dissolved in DMSO-d6,
1H-NMR was measured to find that the polyvinyl alcohol unit content was 99.9 mol% or more, and the isotacticity content was 5%.
6.0%. The intrinsic viscosity of the polyvinyl acetate obtained by acetylating the polyvinyl alcohol measured at 30 ° C. in acetone was 1.26 dl / g. This polyvinyl alcohol-based polymer was easily dissolved in DMSO at room temperature to obtain a 12% by weight solution. The solution was used as a spinning solution, and dry-wet spinning was performed using a single hole having a hole diameter of 0.2 mmφ as a die with a gap of 2.5 cm from a coagulation bath of methanol. The obtained spun yarn was thoroughly washed in methanol and dried under reduced pressure at 25 ° C. The dried yarn was drawn 14 times in an electric furnace having air at 210 ° C. The single yarn fineness of the obtained drawn yarn is 4.5 d, the single yarn strength is 9.0 g / d, the initial elastic modulus is 300 g / d, and the elongation is 1
1.0%, melting point: 215 ° C, WTb: 60 ° C.

Comparative Example 2 Polyvinyl alcohol having a saponification degree of 99.9 mol% and an isotacticity of 22%, obtained by saponifying polyvinyl acetate, and having a limiting viscosity of 0.8 as the intrinsic viscosity of the reacetylated product measured at 30 ° C. in acetone. Was dissolved in dimethyl sulfoxide at 80 ° C. to obtain a 12% by weight solution, which was used as a spinning solution and had a pore diameter of 0.2 mmφ.
Was used as a die, and dry-wet spinning was performed with a gap of 2.5 cm from a coagulation bath of methanol. The obtained spun yarn was thoroughly washed in methanol and dried under reduced pressure at 25 ° C. The dried yarn was drawn 16 times in an electric furnace having air at 250 ° C. The single yarn fineness of the obtained drawn yarn is 6.
0d, single yarn strength 14.0 g / d, initial elastic modulus 360
g / d, elongation: 5.0%, melting point: 241 ° C., WTb: 1
18 ° C.

Comparative Example 3 Polyvinyl alcohol unit content 9 obtained in Example 1
9.9 mol% or more, isotacticity content 78.8
%, A 2% by weight solution obtained by dissolving polyvinyl alcohol having an intrinsic viscosity of 1.89 dl / g measured in acetone at 30 ° C. in dimethyl sulfoxide at 90 ° C. was used as a stock solution for spinning to obtain a pore diameter of 0.1%. Dry-wet spinning was performed using a single hole of 2 mmφ as a die with a gap of 2.5 cm from the coagulation bath of methanol, but severe thread breakage occurred near the die and fiberization was impossible.

[0030]

As apparent from the above examples, according to the present invention, a spinning solution having excellent spinnability can be obtained.
In addition, by using this spinning solution, a method for producing a highly productive fiber free from thread breakage or the like can be provided. In addition, the fiber obtained in this manner retains processing characteristics such as excellent drawability of the fiber obtained from the conventional isotactic polyvinyl alcohol-based polymer,
Various physical properties such as water resistance and heat resistance are extremely superior to fibers made of a polyvinyl alcohol-based polymer which is close to ordinary atactic. In addition, the polyvinyl alcohol-based fiber obtained by the present invention, taking advantage of the above characteristics, including the use of conventional polyvinyl alcohol-based fibers, greatly expanded its application range, further rubber, plastic and It is expected to be used as a fiber material for capturing cement and other materials.

Claims (2)

[Claims] An isotacticity content of 72% or more as indicated by a triad, and an intrinsic viscosity of the acetylated polyvinyl acetate in acetone at 30 ° C. of 0.7 dl / g.
The above polyvinyl alcohol polymer is dissolved by heating in a solvent containing dimethyl sulfoxide, water or a mixed solution thereof at a temperature of 100 ° C. to 180 ° C., and the concentration is adjusted to 3% to 25% by weight. A process for producing a spinning dope. 2. A method for producing a fiber, comprising using the spinning dope obtained by the method of claim 1.