JPH0742019A - Water-soluble polyvinyl alcohol-based fiber and production thereof - Google Patents

Abstract

PURPOSE:To obtain polyvinyl alcohol-based fiber having easy solubility in water at low temperatures and thermal adhesion without causing the sticking and trouble in steps for forming nonwoven fabrics or spinning, knitting or weaving the fiber. CONSTITUTION:This heat-bondable water-soluble polyvinyl alcohol (PVA)-based fiber is composed of a polyvinyl alcoholic polymer having 50-95mol% content of vinyl alcohol unit and 30-3000 average polymerization degree and has 140-205 deg.C melting point, <=5 deg.C dissolution temperature in water and 0.1-20dr single filament denier substantially without any sticking. Furthermore, this method for producing the fiber performing the wet or dry jet-wet spinning of a specific solution of the PVA-based polymer into a >=3C oxygen-containing hydrocarbon and subjecting the resultant coagulated yarn to specific treatment. Thereby, e.g. a base fabric for chemical laces can be produced with a high efficiency.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low-temperature easily water-soluble fiber using a polyvinyl alcohol-based polymer having a low melting point (hereinafter abbreviated as PVA-based) and a method for producing the same, which has both thermal adhesiveness and water solubility. For example, the chemical lace base fabric can be preferably used as a material that can be produced with high efficiency.

[0002]

2. Description of the Related Art Conventionally, as water-soluble fibers that are soluble in water, PVA fibers, cellulosic fibers such as carboxymethyl cellulose, polyalginic acid fibers, and polyalkylene fibers have been known. Only PVA-based fibers have the mechanical properties necessary for stable passage through the non-woven process such as the above and the woven or knitted process such as spinning and knitting.

As a method for producing PVA-based fibers, a method of dry-spinning a concentrated aqueous solution of PVA (Japanese Patent Publication No. 43-8992, etc.) and a method of wet-spinning an aqueous solution of PVA into an aqueous solution of a dehydrating salt such as Glauber's salt (Japanese Patent Laid-open Publication No. S60-12065) Japanese Patent Laid-Open No. 62-215011), a method of dry-wet spinning an organic solvent solution of PVA in methanol, which is a solidifying solvent having 1 carbon atom (Japanese Patent Laid-Open No. 1-1999)
229805). In the dry spinning of partially saponified PVA consisting only of a vinyl acetate unit and a vinyl alcohol unit, it is difficult to fiberize PVA having a saponification degree of 85 mol% or less without single-yarn hardening. Further, JP-A-49-35622 and JP-B-53-
Japanese Patent No. 10174 proposes to obtain water-soluble fibers by dry-spinning allyl alcohol or carboxylic acid-modified PVA, but heat-bondable PVA-based fibers having a melting point of 205 ° C. or less are hard-to-yarn hard. I can't get it without wearing it. Therefore, in order to enable heat bonding, Japanese Patent Laid-Open No. Sho 62-62
In Japanese Patent Application Laid-Open No. 45777/1987, it is proposed to apply a mixture of a solid solvent of PVA and a binder to the dry-spun fiber, but there is a problem that the texture is hard or the applied product falls off. Further, the method of wet-spinning an aqueous solution of PVA in a dehydrating salt bath adheres to the fibers, and when washed with water to remove the adhering salts, the fibers are hard-adhered between the single yarns, so that the post-process passability is improved. There's a problem. Further, an organic solvent solution of PVA having a saponification degree of 80 mol% or more is dry-wet spun in methanol, which is a solidifying solvent having 1 carbon atom, and allowed to stay in the methanol bath for 5 seconds or more and then stretched 10 times or more to have a strength of 10 g. Although it has been proposed to obtain a water-soluble fiber having a ratio of / d or more (Japanese Patent Laid-Open No. 1-229805), a saponification degree of 85 having a low melting point is used.
If the content of PVA is less than mol%, it is not possible to obtain water-soluble fibers without sticking. A melt spinning method is also conceivable as a spinning method other than the above, but a water-soluble PVA-based polymer has a small difference in melting point and thermal decomposition temperature, and normal spinning cannot be performed.

[0004]

In the prior art, as described above, it is not possible to spin a PVA polymer having a low melting point without sticking, and therefore a PV having a melting point of 205 ° C. or lower.
A type fiber is not obtained. Therefore, attempts have been made to attach a large amount of a low-melting solid solvent to obtain the heat-melting property, but there are problems such as hand-hardening and dropping. Therefore, 205
A PVA-based fiber having a melting point of ℃ or less and a thermal adhesiveness and water-solubility suitable for practical use has not been obtained, and a thermal adhesive capable of responding to high-speed production of non-woven fabric such as chemical lace base cloth. There has been a strong demand for PVA fibers having both water-solubility and water-solubility.

The inventors of the present invention have conducted extensive studies to obtain PVA fibers having both the above-mentioned thermal adhesiveness and water solubility, and as a result, the spinning stock solution in which the low melting point PVA is dissolved is oxygenated carbonized with 3 or more carbon atoms. By solidifying with hydrogen, wet drawing, and then extracting with oxygen-containing hydrocarbon having 3 or more carbon atoms, a water-soluble PVA fiber having a lower melting point can be obtained without sticking as compared with the conventional water-soluble PVA fiber. Therefore, the present invention has been completed. That is, an object of the present invention is to provide a water-soluble PVA-based fiber which has a low melting point, is easily heat-bonded, and has no sticking as compared with the conventional water-soluble PVA-based fiber. It is another object of the present invention to provide an industrial production method of such a new high-performance fiber.

[0006]

The above-mentioned problems of the present invention are as follows.
(1) 50 to 95 mol% of vinyl alcohol unit,
A polyvinyl alcohol-based polymer having an average degree of polymerization of 30 to 3000, a melting point of 140 to 205 ° C., a water dissolution temperature of 5 ° C. or less, and a single yarn denier of 1 to 20 dr. Fibre, and (2) vinyl alcohol unit 50-95 mol%,
The average degree of polymerization is 30 to 3000, and the melting point in the fibrous state is 140.
To 205 ° C., a polyvinyl alcohol-based polymer is dissolved in a stock solution solvent capable of dissolving the polymer, and the obtained spinning dope is solidified with the spinning dope. The oxygen-containing hydrocarbon having 3 or more carbon atoms. And a stock solution solvent, the weight composition ratio of which is 95/5 to 40/60, solidified by a solidification solution, subjected to a wet stretching of 3 to 8 times, and further undiluted with an oxygen-containing hydrocarbon solvent having 3 or more carbon atoms. Extract the solvent, 12
A method for producing a water-soluble polyvinyl alcohol fiber, which comprises drying at 0 ° C. or lower. Can be solved by

The polymers of the present invention have 50 to 95 mol% vinyl alcohol units. If it is less than 50 mol%, fibers having the mechanical properties necessary for passing through the subsequent steps such as carding and spinning cannot be obtained. In the case of so-called partially saponified PVA in which the remaining unit is only vinyl acetate unit, when the vinyl alcohol unit is 80 mol% or more (that is, the saponification degree is 80 mol% or more), the melting point of the obtained fiber is 205 ° C.
And the fiber having excellent thermal adhesiveness cannot be obtained.
When a unit other than the vinyl alcohol unit and the vinyl acetate unit is contained (so-called PVA is modified), it depends on the type of the modified unit, but for example, a unit having a large crystallization-inhibiting effect (itaconic acid, maleic anhydride, arylsulfonic acid). Etc., the melting point does not exceed 205 ° C. even when the vinyl alcohol unit is up to 95 mol%, so that it can be preferably used in the present invention. As a unit other than the vinyl alcohol unit and the vinyl acetate unit of the present invention, ethylene, allyl alcohol, itaconic acid, acrylic acid, maleic anhydride and a ring-opened product thereof, vinylpyrrolidone, arylsulfonic acid, and a part or the whole thereof are neutralized. A thing etc. are illustrated. The content of these modifying units depends on the type of modifying group, but at least 5 mol% is necessary.

The average degree of polymerization of the polymer used in the present invention is 3
It is 0 to 3000. When the average degree of polymerization is less than 30, fiberization is difficult and the obtained fiber is brittle. Average degree of polymerization is 3
If it exceeds 000, the viscosity when melted by heat is high and it does not spread sufficiently, so that the adhesive area cannot be made large and the adhesive strength becomes low. The average degree of polymerization is more preferably 50 to 2000, and even more preferably 100 to 1300. The melting point of the fiber of the present invention is 140 to 205 ° C. Melting point 140
It is difficult to obtain fibers having a temperature of less than 0 ° C without sticking, and if the melting point exceeds 205 ° C, the thermal adhesiveness of the fibers becomes insufficient.
The melting point of the fiber is more preferably 150 to 200 ° C, and most preferably 160 to 190 ° C. In the present invention, the melting point is the differential calorimeter DSC- manufactured by Mettler.
20 means the temperature at which an endothermic peak is shown in the first temperature increase when 10 mg of the sample is heated from 50 ° C. to 300 ° C. at 20 ° C./min in a nitrogen atmosphere. The fiber of the present invention has a water dissolution temperature of 5 ° C. or lower, and is also characterized by being easily soluble in water at low temperature. If the water dissolution temperature exceeds 5 ° C., it is difficult to say that it is easily soluble in water at a low temperature, and the dissolution rate becomes low, which is not preferable. In the present invention, the water dissolution temperature is 2 mg / dr for the fiber.
The temperature is the temperature at which the material melts when the load is suspended, immersed in water, and the temperature of the water is raised at a rate of 2 ° C./min.

The fiber of the present invention has a single yarn denier of 0.1 to 20.
It is characterized in that there is substantially no hardening in dr. In order to improve the thermal adhesiveness, it is preferable that the single yarn denier is small,
If it is less than 0.1 dr, it is difficult to fiberize it without hardening.
Industrial production efficiency is low and manufacturing cost is high. When the single yarn denier exceeds 20 dr, not only a soft texture is not obtained, but also the specific surface area is reduced and only a poor thermal adhesiveness is obtained. Single yarn denier is 0.3
It is more preferably -10 dr, more preferably 0.5-5 dr, and most preferably 1-3 dr. Further, if there is hard adhesion, the denier of single yarn is substantially increased and the thermal adhesiveness is deteriorated, and a uniform product cannot be obtained. The term "substantially free from sticking" as used in the present invention means that when the multifilament of the present invention is pulled and cut,
It means that 0% or more are separated one by one.

In the present invention, the vinyl alcohol unit was obtained by analyzing the NMR spectrum. The average degree of polymerization is JIS-K67 when it is not ion-modified.
According to JIS-K6726, it was measured from the intrinsic viscosity of a 30 ° C. aqueous solution based on No. 26, or from the intrinsic viscosity of a 1 M NaCl aqueous solution when ion-modified.

Next, a production example of the low melting point water-soluble PVA fiber of the present invention will be described. The fiber of the present invention has a vinyl alcohol unit of 50 to 95 mol% and an average degree of polymerization of 30.
˜3000, a spinning stock solution obtained by dissolving the above-mentioned PVA-based polymer having a fibrous melting point of 140 to 205 ° C. in a solvent, and an oxygen-containing hydrocarbon having a carbon number of 3 or more and having a solidification ability with respect to the stock solution. And the stock solution solvent, and its weight composition ratio is 95 /
It is solidified with a solidifying solution of 5 to 40/60, and wet-stretched 3 to 8 times in an oxygen-containing hydrocarbon solvent having 3 or more carbon atoms, and then a stock solution solvent is prepared with an oxygen-containing hydrocarbon solvent having 3 or more carbon atoms. It can be manufactured by extracting and then drying at 120 ° C. or lower.

As the undiluted solvent for the PVA polymer of the present invention, dimethyl sulfoxide (hereinafter abbreviated as DMSO),
Glycerin, ethylene glycol, water, a concentrated aqueous solution of zinc chloride or rhodan salt, a mixed solvent thereof, or the like can be used, but DMSO, glycerin, ethylene glycol, and water are preferable, and DMSO is more preferable. When a low-saponification degree PVA-based polymer having a vinyl acetate unit is used in the present invention, if the dissolution liquid has a strong alkalinity, a saponification reaction may occur during dissolution, defoaming, or leaving, and the melting point of the fiber may increase. Although addition of strong alkaline substances such as caustic soda should be avoided, the saponification reaction does not occur in DMSO solution or under weak alkaline such as addition of sodium acetate. Of course, an acid may be added to adjust the acidity. In the case of an ionic group-modified PVA such as carboxylic acid or sulfonic acid, the pH may be adjusted with caustic soda for neutralizing ions.
The polymer concentration varies depending on the degree of polymerization and the solvent, but is 6 to 6
0% is typical. For the dissolution, it is preferable to stir the solution under a reduced pressure after substituting with nitrogen, from the viewpoints of preventing oxidation, decomposition, crosslinking reaction and suppressing foaming.

The obtained spinning dope is composed of an oxygen-containing hydrocarbon having 3 or more carbon atoms having a solidifying ability with respect to the dope and a solvent of the dope, and the weight composition ratio thereof is 95/5 to 40/60. It is an important point of the fiber production method of the present invention to be solidified. The solidification referred to in the present invention means that the spinning stock solution with fluidity changes to a solid with no fluidity, both gelling which solidifies without changing the composition of the stock solution and coagulation with which the composition of the stock solution changes and solidifies. Include. Examples of the oxygen-containing hydrocarbon having a carbon number of 3 or more and having a solidifying ability with respect to the PVA-based polymer spinning solution include alcohols such as propanol and butanol, ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone, methyl acetate, ethyl acetate and the like. The fatty acid esters of are mentioned, and these are used as a mixture of one kind or more. Of these, acetone and methyl acetate are preferable. Methanol and ethanol conventionally used for conventional organic solvent-based spinning do not have sufficient solidification ability for low-saponification and / or highly-modified low-melting point PVA-based polymers as in the present invention, and fibers without sticking I can't get it. For high melting point PVA-based polymers close to highly saponified and / or low-modified pure PVA, the oxygen-containing hydrocarbons having 3 or more carbon atoms have an excessively large solidifying ability, so that they are more homogeneous than methanol or ethanol solidified shino. However, it is not possible to obtain a fiber having a porous fiber structure and satisfactory performance, whereas a polymer used for the fiber of the present invention and an oxygen-containing hydrocarbon having 3 or more carbon atoms behaves at all. However, it was found for the first time that a homogeneous solidified yarn can be obtained and a fiber having satisfactory performance can be stably obtained. It is estimated that the balance between the solidification properties of the polymer and the solidification ability of the solidification liquid is important. The solidified liquid used in the present invention has a weight composition ratio of 95/5 to 40/60 of the oxygen-containing hydrocarbon having 3 or more carbon atoms and the stock solution solvent. It is important to adjust the above-mentioned solidification ability by allowing a stock solution solvent to coexist in the solidification solution. Further, it is preferable to mix the stock solution solvent with the solidifying solution from the viewpoint of solidifying the stock solution solvent and reducing the recovery cost of the solvent. The temperature of the solidifying solution is not particularly limited, but is usually between -20 and 30 ° C. From the viewpoint of homogeneous solidification and energy saving, the solidification liquid temperature is preferably -10 to 20 ° C, more preferably -5 to -15 ° C,
The most preferred tendency is 0 to 10 ° C. The spinning method of the present invention is not particularly limited whether it is wet spinning or dry wet spinning. Although any spinning method can be adopted if the spinning conditions suitable for each spinning method are set, the wet spinning method is preferable from the viewpoint of suppressing sticking when the nozzle is made porous.

The solidified thread obtained is 3 in oxygenated hydrocarbon.
~ 8 times wet drawing. The wet drawing bath may contain a stock solution solvent. It is important to increase the wet draw ratio within the range where there is no fluff in order to suppress the sticking of Ishino. Therefore, it is also effective to raise the temperature of the wet drawing bath to near the boiling point. Next, the wet-stretched Shinoshino is contacted with a solidifying solvent to extract and remove the stock solution solvent from the Shinoshino. In some cases, it has been proposed to use decalin having 3 or more carbon atoms as a cooling and solidifying solvent in gelation spinning, but in this case also, methanol is used as the solvent for extracting and removing the stock solution solvent. In the polymer of the fiber of the present invention, even if an organic solvent having 1 carbon atom (for example, methanol) is used in the extract, it swells and hardens,
An organic solvent having 2 or less carbon atoms cannot be used. Therefore, it is necessary to use an oxygen-containing hydrocarbon having 3 or more carbon atoms as the extract. As the extraction / removal method, a method of contacting the oxygen-containing hydrocarbon liquid with the wet-stretched shishino is used, and particularly preferably, a method of bringing the oxygen-containing hydrocarbon liquid and the shishino into countercurrent contact. The contact time is 15 seconds or more,
Particularly preferably 20 seconds or more. In order to increase the extraction rate and improve the extraction, the oxygen-containing hydrocarbon liquid is preferably heated. In general, a method of performing wet drawing and then immediately drying without extracting and removing the solvent of the undiluted solution has been used, but in the case of a fiber made of a polymer which easily causes inter-filament sticking as in the present invention, However, only the conventional method as described above causes sticking between single yarns during drying.
Therefore, in the present invention, the solvent extraction treatment after the wet drawing is an extremely important step.

Then, the thread is extracted after the stock solution solvent extraction. In the present invention, it is dried in a gas bath at 120 ° C. or lower. 1
Drying at a temperature above 20 ° C. should be avoided because low-melting-point fibers such as the fibers of the present invention will adhere firmly. In addition, it is also effective to suppress hard adhesion by adhering a hydrophobic oil agent such as a mineral oil type, a silicon type, a fluorine type or the like before drying, or by causing a shrinkage to relax a shrinking stress during drying.

After drying, the raw yarn may be subjected to dry heat drawing and / or dry heat treatment (including dry heat shrinkage), if necessary. Since the melting point of this fiber is lower than that of conventional PVA-based fiber, the temperature of dry heat drawing and / or dry heat treatment is 80
It is preferable to carry out at a low temperature of up to 200 ° C.

As described above, according to the present invention, a spinning dope obtained by dissolving a low-saponification and / or high-modification low-melting point PVA polymer, which cannot be used as a fiber polymer, is solidified in a specific solidifying solvent. Only by combining proper solidification and various measures to prevent sticking will there be no sticking 1
A heat-adhesive and low-temperature easily water-soluble fiber having a melting point of 40 to 205 ° C. was obtained, which cannot be obtained by conventional wet spinning, dry wet spinning, or dry spinning.

[0018]

EXAMPLES The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

Example 1 PVA having 73 mol% of vinyl alcohol units and 27 mol% of vinyl acetate units and having a degree of polymerization of 650 and a degree of saponification of 73 mol% was mixed with DMSO, and the atmosphere was replaced with nitrogen. The mixture was dissolved under reduced pressure with stirring at 90 ° C. for 8 hours, and then defoamed at 90 ° C. for 8 hours under the same 110 Torr to obtain a DMSO solution containing 40% PVA. The spinning dope was kept at 90 ° C. and wet-spun at 2 ° C. into an acetone / DMSO mixed solidified liquid having a mixture weight ratio of acetone and DMSO of 85/15 through a nozzle having 100 holes and a hole diameter of 0.12 mmφ. The obtained Itoshino is acetone / DMSO = 9
Wet stretched 4.2 times in an 8/2 mixture, and then heated acetone and Ishino were brought into countercurrent contact to extract and remove DMSO, and a mineral oil type oil agent was added in an amount of 1% / polymer. After 8
It was dried with a hot air dryer at 0 ° C. and a multi-filament of 300 dr / 100f was wound up. A 5% shrinkage was applied before drying. The degree of saponification of the obtained fiber was 74 mol%, which was almost the same as that of the raw material PVA, the melting point was as low as 178 ° C., the water dissolution temperature was 2 ° C. or lower, the single yarn denier was 3 d, and the multifilament was a single filament. Hard adhesion between the yarns was not seen at all and it was very flexible. Stack the obtained filaments in a cross,
It was found that when it was subjected to high temperature pressure bonding at 150 ° C. for 1 minute, it was well sticked and had thermal adhesiveness.

Comparative Example 1 Spinning was carried out in the same manner as in Example 1 except that 100% methanol was used as the solidifying liquid, but a normal solidified yarn was not obtained due to poor solidifying property.

Comparative Example 2 Spinning was carried out in the same manner as in Example 1 except that methanol was used in place of acetone to extract and remove the solvent of the stock solution after wet drawing.
Although it was solidified in an acetone solution and wet-stretched to obtain a good wet-stretched Shinoshino, when it was immersed in methanol to extract and remove DMSO in the Shinoshino, the Shinoshino swelled with methanol and after 1 minute immersion It became difficult to properly guide the yarn, and the yarn was broken.

EXAMPLE 2 PVA and DMSO having a vinyl alcohol unit content of 78 mol% and a vinyl acetate unit content of 22 mol%, a degree of polymerization of 450 and a saponification degree of 78 mol% were mixed and dissolved in the same manner as in Example 1. Degassing gave a DMSO solution with 48% PVA. This spinning dope was dried and wet-spun through a nozzle having a hole number of 50 and a hole diameter of 0.15 mmφ through a 1 cm air cap to a methyl acetate / DMSO mixed solidified solution having a mixture weight ratio of methyl acetate and DMSO of 65/35 at 2 ° C. . The obtained Shinoshino was subjected to 6 times wet drawing in a mixed solution of methyl acetate / DMSO = 90/10, and was brought into countercurrent contact with heated methyl acetate to extract and remove DMSO.
3% / after polymer application, dried at 100 ° C under a nitrogen stream and dried at 10
A multifilament of 0 dr / 50f was obtained. The melting point of the obtained fiber was 194 ° C., and the water dissolution temperature was 5 ° C. or lower. The single yarn denier was 2d, and the multifilament showed no sticking between the single yarns and was highly flexible.
A staple obtained by crimping and cutting this fiber and a staple of PVA fiber having a saponification degree of 99.9 mol% are mixed in half and a carded web is obtained at 170 ° C.
When subjected to a heat calender treatment of × 50 kg / cm, a heat-bonded nonwoven fabric was obtained.

Comparative Example 3 PVA and DMSO having a vinyl alcohol unit content of 93 mol% and a vinyl acetate unit content of 7 mol% and a degree of polymerization of 600 and a saponification degree of 93 mol% were mixed, and the same procedure as in Example 1 was conducted. A DMSO solution containing 38% PVA was obtained. This spinning dope was treated in the same manner as in Example 1 except that methanol was used in place of acetone in Example 1 to obtain 300 dr / 10.
0f multifilament was obtained. Saponification degree 93 mol%
In PVA of No. 3, hard adhesion as in Comparative Example 1 and Comparative Example 2 did not occur, and spinning could be performed extremely smoothly. The obtained fiber had a high melting point of 212 ° C and a water dissolution temperature of 8 ° C. When this fiber was subjected to a heat adhesion test at 150 ° C,
It didn't fuse much.

Example 3 Maleic acid-modified PVA and DMS having a maleic acid unit content of 8 mol%, a vinyl acetate unit content of 2 mol%, a vinyl alcohol unit content of 90 mol%, and a polymerization degree of 500.
O was mixed and dissolved and defoamed in the same manner as in Example 1 to obtain a DMSO solution containing 42% of PVA. This spinning dope was used in Example 1.
A 300d / 100f multifilament was obtained in the same manner as described above. The melting point of the obtained fiber was as low as 180 ° C., the water dissolution temperature was 4 ° C. or less, the strength was 1.2 g / dr, and single-yarn hard fixation was not observed. When this fiber was evaluated for thermal adhesiveness at 150 ° C., the adhesiveness was good.

Comparative Example 4 A maleic acid-modified PVA having a maleic acid unit of 2.5 mol%, a vinyl acetate unit of 1 mol%, a vinyl alcohol unit of 96.5 mol% and a polymerization degree of 750 was used. It was spun in the same manner as in. The melting point of the obtained fiber was as high as 210 ° C, and the water dissolution temperature was 10 ° C. When the thermal adhesion of the obtained fiber was evaluated in the same manner as in Example 3, the thermal adhesion was inferior to that of Example 3.

[0026]

INDUSTRIAL APPLICABILITY According to the present invention, a low-saponification and / or low-melting-point PVA polymer, which cannot be used as a fiber polymer in the past, is wet or dry-wet spun under specific conditions such as using a specific solidifying solvent. According to the above, a heat-adhesive and low-temperature easily water-soluble fiber having a melting point of 140 to 205 ° C. without sticking is obtained. This fiber not only can greatly simplify the manufacturing process by utilizing thermal adhesiveness in the production of chemical lace base fabric, but it can also be easily dissolved and removed at low temperature, so it can also save energy.
It has great industrial utility value.

Front page continued (72) Inventor Shunpei Naramura 1621 Sakata, Kurashiki City, Okayama Prefecture Kuraray Co., Ltd.

Claims (2)

[Claims] 1. The vinyl alcohol unit is 50 to 95.
Made of polyvinyl alcohol-based polymer having a mol% and an average degree of polymerization of 30 to 3000, and a melting point of 140 to 205 ° C.,
Water dissolution temperature is 0 ~ 5 ℃, single yarn denier is 0.1 ~ 20d
Water-soluble polyvinyl alcohol fiber having substantially no sticking of r. 2. The vinyl alcohol unit is 50 to 95.
Polyvinyl alcohol-based polymer having a mol%, an average degree of polymerization of 30 to 3000, and a fibrous melting point of 140 to 205 ° C. is dissolved in a stock solution solvent having a solubility for the polymer, and the obtained spinning stock solution is The spinning stock solution is solidified by a solidification solution having an oxygen-containing hydrocarbon having a carbon number of 3 or more and a stock solution solvent having a weight composition ratio of 95/5 to 40/60, and is solidified to a moisture content of 3 to 8 times. Stretching is performed, and the stock solution solvent is extracted with an oxygen-containing hydrocarbon having 3 or more carbon atoms,
A method for producing a water-soluble polyvinyl alcohol fiber, which comprises drying at 120 ° C. or lower.