JPH11200152A - Polyvinyl alcohol-based flame retardant fiber and method for producing the same - Google Patents

Abstract

(57) Abstract: A method for stably obtaining a fiber having high strength, no melt drip, no deterioration in flame retardancy due to washing or the like, and excellent flame retardancy. The present invention relates to a flame-retardant fiber obtained by the above method. A vinyl alcohol-based polymer (hereinafter abbreviated as PVA) and a vinyl chloride-based polymer (hereinafter abbreviated as PVC) in which a monomer having a hydroxyl group is copolymerized in an amount of 1 to 30% by weight.
Is added and dissolved in a common polar organic solvent together with a tin compound and / or an antimony compound alone or in a mixture, and PVA is used as a spinning solution containing sea components and PVC is island components.
This is wet or dry wet spun into a coagulation bath, then dried,
It is drawn and further heat-treated as necessary to produce a flame-retardant fiber.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyvinyl alcohol (abbreviated as PVA) flame-retardant fiber which can be produced industrially at low cost and has excellent cost performance, and a method for producing the same. The present invention relates to a fiber that can be suitably used for clothing, materials for curtains and carpets, and industrial materials for car seats and vehicle spring receiving materials, and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, flame-retardant fibers include acrylic and polyester fibers copolymerized with a flame-retardant comonomer, regenerated cellulose fibers into which a flame-retardant agent has been kneaded or reacted, and the polymer itself having a flame-retardant property. Thermoset fibers, aramid fibers, cotton and wool post-processed with flame retardant agents are on the market. Acrylic fiber generates cyan gas when burning,
Polyester fiber has melt drip, thermosetting fiber has low fiber strength, aramid fiber is extremely expensive, cotton and wool have problems such as texture hardening due to post processing and poor washing durability, and improvements are being studied respectively. .

[0003] On the other hand, PVA-based flame-retardant fibers are also disclosed in
No. 12920, Japanese Patent Publication No. 49-10823, Japanese Patent Publication No. 51-19494, etc. are known, such as clothing for protective clothing, living materials such as curtains and carpets, car seats and vehicle spring receiving materials, etc. Although it is used for industrial materials, it is not satisfactory in terms of cost performance depending on the application, and it is difficult to further expand sales.

[0004] Conventional PVA-based flame-retardant fibers are those to which a vinyl chloride-based polymer (abbreviated as PVC) is added.
C is insoluble in water which is a spinning solvent, so it is inexpensive
It is impossible to use PVC powder, and an expensive polyvinyl chloride emulsion having a small particle size must be used.
Also, the mixed aqueous solution of PVA and PVC emulsion is not stable at around 70 to 100 ° C near the spinning temperature, and the mechanical stability especially when passing through a gear pump is insufficient. It is necessary to use or add a surfactant or a water-soluble polymer, which further increases the cost.

The conventional PVA-based flame-retardant fiber is composed of an aqueous emulsion of PVC having an emulsion particle size of 0.01 to 0.08 μm and a PVA-based flame-retardant fiber.
A aqueous solution is mixed, and a liquid obtained by adding an aqueous dispersion of tin or an antimony compound as a flame retardant is used as a spinning solution, wet spinning is performed in a solidification bath composed of an aqueous solution of silica gel, drying, dry heat drawing, and heat treatment. Further, if necessary, it is produced by acetalization treatment with formalin or the like to improve hot water resistance. In order to obtain high-strength fibers, a spinning solution obtained by adding boric acid to a mixed aqueous solution of PVA and PVC emulsion is discharged into a solidification bath composed of a mixed aqueous solution of caustic soda and sodium nitrate, and spinning with boric acid is also performed. However, the use of the strong dehydrating salts, such as sodium nitrate, in the solidification bath causes the fiber cross section to have an uneven skin core structure, and the core structure at the center of the cross section tends to have insufficient crystallinity. Therefore, even if a hot water improving treatment such as formalization is performed, there is room for improvement in dimensional stability, especially dimensional stability in wet and dry conditions.

[0006] In view of the above situation, the present inventors have intensively studied the use of inexpensive commercial PVC powder to make PVA-based flame-retardant fibers, and have found that PVA and PVA can be dissolved in a stock solution solvent common to PVA. P
A polyvinyl alcohol-based flame-retardant fiber comprising VC, PVA is a sea-island fiber, and PVC is an island-island fiber with an island component, and the size of the PVC island is 0.2 to 8 μm. I found it. This fiber is not only inexpensive, but also improves strength and dimensional stability in wet and dry conditions.
It is expected to be a PVA-based flame-retardant fiber which is much more cost-effective than A-type flame-retardant fiber.

However, conventional PVC which can be dissolved in a common solvent for PVA and PVA is not sufficiently compatible with PVA, so that the PVC island phase is aggregated with time when the stock solution is left and defoamed. Had to be constantly stirred. In this case, spinning for a short time can be performed smoothly, but when spinning for a long time, there is a problem that the spinning condition becomes poor because a stock solution in which a PVC phase is aggregated in a stagnant portion such as a stock solution pipe is mixed. .

[0008]

As described above, the PVA
The conventional polyvinyl alcohol-based flame retardant fiber made of PVC that can be dissolved in a common stock solution solvent with PVA not only has excellent cost performance, but also improves strength and dimensional stability between wet and dry. There was a problem that the island phases aggregated. The present invention aims to remedy such a problem.

That is, the present invention comprises PVA and PVC in which a monomer having a hydroxyl group is copolymerized in an amount of 1 to 30% by weight.
Is a polyvinyl alcohol-based flame-retardant fiber, characterized in that: is a sea component and PVC is a sea-island fiber of an island component. further,
PVA and PVC are dissolved in a common solvent, and the resulting spinning dope is mixed with PV
Wet or dry-wet spinning in a solidification bath in which a solidifying solvent having a solidifying ability for A and a stock solution solvent are mixed, extraction, drying, drawing, and, if necessary, heat treatment or acetalization to produce PVA-based flame-retardant fibers In doing so, there is provided a method for producing a PVA-based flame-retardant fiber, characterized by satisfying the following conditions (1) and (2). (1) Use of PVC in which 1 to 30% by weight of a monomer having a hydroxyl group is copolymerized. (2) The spinning stock solution contains P in the PVA solution.
It has a phase structure in which islands of a particle diameter of 1 to 50 μm made of a solution of VC are present, and a PVC island diameter change rate is 0 to 1 μm / hr.

Hereinafter, the present invention will be described in detail. First, the sea component, that is, the matrix component of the fiber of the present invention must be PVA. PVA is the only polymer that can form strong intermolecular hydrogen bonds due to PVC that imparts flame retardancy and hydroxyl groups that enable strong sea-island fibers. PVA in the present invention
Means a polymer having a vinyl alcohol unit of 70 mol% or more.Therefore, a monomer such as ethylene, vinyl acetate, itaconic acid, vinylamine, acrylamide, vinyl pivalate, maleic anhydride, or a sulfonic acid-containing vinyl compound is used as a monomer. It may be copolymerized in a proportion of less than mol%. The saponification degree is preferably 80 mol% or more,
For oriented crystallization, PVA in which 95 mol% or more of all the constituent units are vinyl alcohol units is more preferable, more preferably 98 mol% or more, and even more preferably 99 mol% or more.
Mol% or more, most preferably 99.8 mol% or more. PVA
The degree of polymerization is not particularly limited, but the degree of polymerization is preferably 500 or more, more preferably 1500 or more in order to obtain a high-strength fiber. In order to improve hot water resistance, acetalized PVA may be subjected to a post-reaction such as intramolecular and / or intermolecular acetalization with an aldehyde compound typified by formaldehyde after fibrillation.

The island component of the fiber of the present invention must be PVC in which a monomer having a hydroxyl group is copolymerized in an amount of 1 to 30% by weight. Only when PVC is used as the island component can the fiber of the present invention be made into a flame-retardant fiber. PVC has a low degree of crystallinity, lacks fiber-forming ability, or has low strength even if it is formed into fibers.In particular, in the wet spinning method, which is a cost-effective production method for staple fibers, PVC is used.
C fiber is not manufactured. Therefore, PVC is used as an island component in the fiber of the present invention and as a functional polymer for imparting flame retardancy.

In the present invention, it is important to use PVC in which a monomer having a hydroxyl group is copolymerized at 1 to 30% by weight. By using such PVC, the solubility of PVC in a stock solution solvent, which is a common solvent with PVA, is improved. Furthermore, the compatibility with PVA is better than PVC homopolymer and different monomer copolymerized PVC having no hydroxyl group.
Island aggregation is less likely to occur. This is the most important point of the present invention. PVC homopolymers and non-hydroxyl-containing copolymers of different monomers PVC are hydrophobic, so PVA
Is not sufficient, and if the stock solution of Ferent is left untreated, the PVC islands agglomerate, the spinnability becomes poor, and spinning becomes difficult. On the other hand, the hydroxyl group-containing monomer-copolymerized PVC has good compatibility with PVA because of its hydroxyl group. Therefore, even if the stock solution of parent is left alone, aggregation of the PVC island hardly occurs, and stable spinning becomes possible. Further, the parent stock solution with PVA using the hydroxyl group-containing monomer copolymerized PVC has less coloring than the stock solution using the PVC homopolymer and the different monomer copolymerized PVC having no hydroxyl group, so that it is possible to obtain a less colored fiber. it can. This is an unexpected effect, and the cause is not known in detail, but it is difficult to make a polyene structure that causes the hydroxyl-containing monomer to cause coloring.
This is presumed to be due to uniform dispersion in the PVC chain and copolymerization.

The monomers having a hydroxyl group are those which can be copolymerized with PVC such as hydroxyethyl acrylate and hydroxypropyl acrylate. Hydroxypropyl acrylate copolymerized PVC is preferred from the viewpoint of copolymerizability. As the copolymerization amount increases, the aggregation of PVC islands is less likely to occur, but the flame retardancy is reduced. When the copolymerization amount exceeds 30% by weight, the feature of the present invention, that is, high flame retardancy, is reduced.
Not preferred. When the copolymerization amount is less than 1% by weight, the effect of improving the compatibility with PVA by the copolymerization becomes insufficient. It is preferable that the copolymerization amount is 2 to 15% by weight from the viewpoint of the balance between compatibility and flame retardancy. It is important that the hydroxyl group-containing monomer is copolymerized with PVC in order to suppress PVC island aggregation. However, if a third monomer having no hydroxyl group is copolymerized, it will dissolve in the solvent. The solubility and compatibility with PVA are improved, and aggregation of PVC islands can be suppressed even if the copolymerization amount of the hydroxyl group-containing monomer is small. Therefore, the copolymerization amounts of the hydroxyl group-containing monomer and the third monomer are respectively
More preferably, it is 1 to 15% by weight. From the viewpoint of flame retardancy, the copolymerization amount of the hydroxyl group-containing monomer and the third monomer is more preferably 1 to 10% by weight, respectively. Examples of such a third monomer include vinyl acetate and acrylic acid ester, and vinyl acetate is particularly preferable from the viewpoint of more excellent compatibility.

To make PVA a sea component and PVC a island component, PV
A is preferably 55% by weight or more. If the PVA content is less than 55% by weight, some of the PVC may be a sea component, which is not preferable. Also PVC
If the content is less than 10% by weight, the amount of chlorine in the fiber is small and the flame retardancy becomes insufficient. From the balance of flame retardancy and strength, the mixing ratio of PVA / PVC is more preferably from 85/15 to 55/45, and even more preferably from 80/20 to 60/40.

Further, the fiber of the present invention comprises a tin compound and / or
Alternatively, it is preferable to contain the antimony compound alone or as a mixture in an amount of 0.1 to 15% by weight based on the total weight of the polymer, because the flame retardancy is improved. The tin compound referred to in the present invention is not particularly limited as long as it is a compound containing a tin element, but inorganic oxides such as tin oxide and metastannic acid are used in view of a flame retardant enhancing effect as a flame retardant aid and cost performance. preferable. The antimony compound referred to in the present invention is not particularly limited as long as it is a compound containing an antimony element. However, inorganic oxides such as antimony pentoxide and antimony trioxide in terms of flame retardant enhancing effect as a flame retardant aid and cost performance. Are preferred. When the content of the tin compound and / or the antimony compound is less than 0.1% based on the total weight of the polymer, the flame retardancy is insufficient. Even if the content exceeds 10%, the flame retardant effect reaches a plateau, which is disadvantageous in cost performance.
When the content of the tin compound and / or the antimony compound is 0.5
Preferably it is 8% by weight, more preferably 1-6% by weight.

Next, a method for producing the fiber of the present invention will be described. First, PVA and PVC are dissolved in a common solvent to prepare a spinning solution.
As a common solvent, dimethyl sulfoxide (hereinafter referred to as DMSO)
And organic solvents such as dimethylacetamide and dimethylformamide. Especially low-temperature solubility,
DMSO is preferred from the viewpoint of low polymer decomposability. The concentration of the polymer in the stock solution is preferably in the range of 10 to 30% by weight.

As described above, the PVC used is one in which a monomer having a hydroxyl group is copolymerized at 1 to 30% by weight. The spinning solution is composed of a solution of PVC in a PVA solution.
It is important to have a phase structure in which islands of the particle system of 5050 μm are present. The phase structure of the spinning solution referred to in the present invention means that the spinning solution is dropped on a slide glass to a thickness of about 200 μm, and a differential interference microscope apparatus BX- manufactured by Olympus Optical Co., Ltd.
This is a value obtained by taking a photograph using a Model 60 and measuring it. Further, the particle diameter in the present invention means that the majority that can be distinguished when observed with the above-mentioned differential interference microscope has a diameter in the range. The majority of the island diameter of the PVC solution is 50μ
If it exceeds m, the spinnability is not sufficient, which is not preferable in view of the processability. If the majority is less than 1 μm, the PVA cannot form a clear sea phase. More preferably, it has a phase structure having a particle diameter of 5 to 30 μm.

Further, the change rate of the PVC island diameter in the undiluted solution is 0 to 1 μm
It is also important to be / hr. In order to satisfy this requirement, it is important to use a monomer having a hydroxyl group copolymerized at 1 to 30% by weight. The island diameter change rate is a value obtained by dividing the difference between the average PVC island diameter immediately after the end of dissolution of the stock solution and after standing for 15 hours by the standing time, and means the ease of aggregation of PVC islands. Here, the average island diameter is obtained by actually measuring at least 50 island diameters of PVC arbitrarily selected from the above-mentioned differential interference microscopy photograph, and calculating the average value. Island diameter change speed is 1
If it exceeds μm / hr, it occurs when degassing is left after dissolving the stock solution
This is not preferable because the spinning condition becomes poor due to the aggregation of PVC. The smaller the island diameter change rate, the better the stock solution stability,
More preferably, it is 0.5 μm / hr.

The temperature of the stock solution is preferably 100 ° C. or less. 100
When the temperature exceeds ℃, the solubility of PVC is improved, but the decomposition rate is remarkably increased, coloring becomes remarkable, and the polymerization degree is reduced. Therefore, lower temperature is better, but too low
Poor solubility of C and PVA in polar organic solvents. Therefore, a stock solution temperature of 40 ° C. or more and 90 ° C. or less is preferable. More preferably, it is 50 ° C or higher and 80 ° C or lower. The viscosity of the spinning solution is preferably 10 to 400 poise for wet spinning, and 50 to 2000 poise for dry and wet spinning.

The method of dissolving the polymer is not particularly limited, and the two types of polymers may be dissolved individually in a stock solution and mixed at an appropriate ratio. And the method of dissolving two kinds of polymers simultaneously can be adopted. In addition, the spinning solution may be used in combination with an acid or an antioxidant as a polymer stabilizer.

The spinning dope thus obtained is wet-spun or dry-wet spinning through a spinning nozzle into a solidification bath. The wet spinning method, in which the solidification bath is brought into direct contact with the spinning nozzle, is suitable for spinning using a multi-hole nozzle because the fibers can be spun without causing the fibers to stick together even if the nozzle hole pitch is narrowed. Dry-wet spinning with an air gap between them is suitable for high-speed spinning because the elongation at the air gap is large. In the present invention, the wet or dry-wet method can be appropriately selected depending on the purpose and application.

The solidification bath used in the present invention is a mixed solution comprising a solidification solvent and a stock solution solvent. As the solidifying solvent, an organic solvent having a solidifying ability with respect to PVA such as alcohols such as methanol and ethanol, and ketones such as acetone and methyl ethyl ketone is preferable, and a composition ratio of the solidifying solvent / stock solution solvent in the solidifying bath. Is 25 / 75-85
/ 15. The solidification bath is preferably set to a low temperature of -5 to 20 ° C. from the viewpoint of uniform solidification, that is, the high strength chemical point of the obtained fiber.

In the present invention, in order to properly maintain the solidification level, the composition ratio of the organic solvent-based solidifying solvent and the stock solution solvent in the solidification bath is important, and in the present invention, the weight ratio is 25/75.
A range of ~ 85/15 is employed. If the concentration of the undiluted solvent in the solidification bath is less than 15% by weight, the coagulation ability is too high, the nozzle breaks, the spinning condition becomes poor, and the performance of the obtained fiber such as strength and Young's modulus tends to decrease. On the other hand, if the concentration of the undiluted solvent in the solidification bath is more than 75% by weight, sufficient solidification cannot be performed, and the spinning process is poor in passage.
Fibers having satisfactory performance in terms of strength and the like cannot be obtained. A more preferable concentration of the undiluted solvent in the solidification bath is 20 to
70% by weight, most preferably 25-65% by weight.
In the present invention, as described above, the solidification bath is a mixture of the solidification solvent and the undiluted solvent. However, if the amount is small, other liquids and solids may be dissolved therein. In the present invention, the most preferable combination of the solidifying solvent and the stock solution is a combination of methanol and DMSO.

The yarn formed in the solidification bath is sent to a dry heat drawing step after wet drawing, extraction of a stock solution solvent, and drying. In the method of the present invention, it is necessary to perform dry heat stretching so that the total stretching ratio becomes 6 times or more. The total draw ratio in the present invention is a ratio represented by a product of a wet draw ratio and a dry heat draw ratio.
Fibers with excellent Young's modulus cannot be obtained.

Further, a tin compound and / or
Alternatively, it is preferable to disperse the antimony compound alone or in a mixture of 0.1 to 15% by weight based on the total weight of the polymer because flame retardancy is improved. There are no particular restrictions on the distribution method,
When PVA and PVC are charged and dissolved in a common solvent, a single or a mixture of a tin compound and / or an antimony compound may be simultaneously charged.

[0026]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to Examples, but the present invention is not limited by these Examples. The strength and elongation in the examples are measured in accordance with JIS L-1013. The flame retardancy index (LOI) is J
It was measured in accordance with IS K 7201. The color of the fiber is HITACHI
The color was measured using a color analyzer C-2000J, and the color difference was calculated using the L ^* a ^* b ^* system color difference equation.

Example 1 PVA having a degree of polymerization of 1750 and a degree of saponification of 99.8 mol%,
Hydroxypropyl acrylate 15% by weight with polymerization degree 400
The copolymerized PVC was added to DMSO together with metastannic acid, and 8
Stir and dissolve at 240 rpm under nitrogen stream at 0 ° C for 5 hours, PVA / PV
A mixed spinning dope having a weight ratio of C of 67/33, a polymer concentration of 18% by weight, and metastannic acid of 1% by weight was obtained. When this stock solution was observed with a differential interference microscope, the PVC solution was approximately 10μ in the PVA solution.
It was found to have a phase structure existing as an island component having an island diameter of m. The change rate of PVC island diameter is 0 μm /
After defoaming at 80 ° C. for 15 hours, the spinnability remained the same as immediately after dissolution, and the spinning condition was extremely good even after continuous spinning for 20 hours. The obtained spinning dope at 80 ° C.
Through a spinneret having a hole and a hole diameter of 0.08 mm, wet spinning was performed in a solidification bath having a weight ratio of methanol / DMSO of 70/30 and a temperature of 0 ° C. Then, while extracting DMSO with methanol, the film was subjected to 3.5-fold wet stretching, dried with hot air at 100 ° C, and then subjected to 4.0-fold dry-heat stretching at 228 ° C. The resulting fiber is
Cross-sectional observation by TEM showed that PVA was sea and PVC was island-island structure. The strength of this fiber was 8.5 g / d, and the LOI value was 37. The color difference of the fibers was as low as 9.5.

Comparative Example 1 A stock solution was dissolved, spun and stretched in the same manner as in Example 1 except that PVC copolymerized with 15% by weight of vinyl acetate was used. When the spinning solution immediately after dissolution was observed with a differential interference microscope, PV
It was found that the PVC solution had a phase structure in which the PVC solution existed as an island component having an island diameter of about 25 μm in the A solution. However, the PVC island diameter change rate of this stock solution is as large as 2.0 μm / hr,
When left to defoam at 80 ° C for 15 hours, the spinnability was quite poor and spinning was impossible. Therefore, spinning was possible by continuously stirring from the start of melting to the end of spinning. However,
After continuous spinning for 20 hours, the stock solution in which the PVC phase was aggregated was mixed in the stagnant portion of the stock solution pipe, resulting in poor spinning condition. Observation of the cross section of the obtained fiber by TEM revealed that the PVA had a sea-island structure, and the PVC had a sea-island structure. The strength of this fiber was 8.4 g / d, the LOI value was 37, which was almost the same as in Example 1, but the color difference of the fiber was 13.0, which was considerably colored.

Example 2 A stock solution was dissolved, spun, and stretched in the same manner as in Example 1 except that PVC in which 5% by weight of hydroxypropyl acrylate and 10% by weight of vinyl acetate were copolymerized was used. Observation of the obtained spinning solution with a differential interference microscope revealed that PVC was contained in the PVA solution.
It was found that the solution had a phase structure that existed as an island component having an island diameter of about 15 μm. In addition, the PVC island diameter change rate was 0.33 μm / hr. Even after defoaming at 80 ° C. for 15 hours, the spinnability was almost the same as immediately after dissolution, and the spinning condition was good even after continuous spinning for 20 hours. The obtained fiber is TEM
According to the cross-sectional observation by, PVA was sea and PVC was island-island structure. The strength of this fiber was 8.6 g / d, the LOI value was 37 and Example 1
Was almost the same. The color difference of the fiber was 11.0, which was higher than that of Example 1, but was significantly lower than that of Comparative Example 1.

Example 3 8% by weight of hydroxypropyl acrylate copolymerized P
Except for using VC, dissolving the stock solution, spinning,
Stretching was performed. Observation of the obtained spinning dope with a differential interference microscope revealed that the PVA solution had a phase structure in which the PVC solution was present as an island component having an island diameter of about 15 μm. The PVC island diameter change rate is 0.4 μm / hr, 80
Even after defoaming at 15 ° C., the spinnability was almost the same as immediately after dissolution, and the spinning condition was good even after continuous spinning for 20 hours. Observation of the cross section of the obtained fiber by TEM revealed that the PVA had a sea-island structure, and the PVC had a sea-island structure. The strength of this fiber is 8.4
g / d was almost the same as that of Example 1, but the LOI value was 39, which was higher than that of Example 1. The fiber color difference is 10.
Although it was colored more than 2 and Example 1, the value was much lower than that of Comparative Example 1.

Comparative Example 2 A stock solution was dissolved, spun and stretched in the same manner as in Example 1, except that PVC in which vinyl acetate was copolymerized at 8% by weight was used. When the obtained spinning stock solution was observed with a differential interference microscope, PVA
It was found that the PVC solution had a phase structure that existed as an island component having an island diameter of about 27 μm in the solution. However, the PVC island diameter change rate of this stock solution was as large as 2.4 μm / hr,
When left to defoam at 15 ° C., spinnability was considerably poor and spinning was impossible. Therefore, spinning was possible by continuously stirring from the start of melting to the end of spinning. However, 20
When spinning was performed for a long time and for a long time, the stock solution in which the PVC phase was aggregated was mixed in the stagnant portion of the stock solution pipe, and the spinning condition became poor. Observation of the cross section of the obtained fiber by TEM revealed that the PVA had a sea-island structure, and the PVC had a sea-island structure. The strength of this fiber was 8.2 g / d, which was almost the same as that of Example 1, but the LOI value was 39, which was higher than that of Example 1. On the other hand, the color difference of the fibers was 13.5, which was considerably colored.

[0032]

The fibers of the present invention are flame-retardant acrylic fibers, flame-retardant polyester fibers, thermosetting fibers, aramid fibers,
Compared with non-PVA-based flame-retardant fiber materials such as flame-retardant cotton and flame-retardant wool, PVA-based flame-retardant fibers are superior in terms of combustion gas toxicity, melt drip properties, strength, cost, washing durability, and texture. It is an invention relating to the improvement of. Conventional PVA-based flame-retardant fiber is a special and expensive PVC for obtaining flame retardancy.
Using an aqueous emulsion solution, a spinning solution mixed with an aqueous PVA solution is spun into an aqueous solution containing silica gel, stretched, heat-treated,
Although it is manufactured by formalization, the present invention is inexpensive.
Using PVC powder, a mixed solution having a phase structure in which the PVC solution forms an island phase in the PVA solution by dissolving it in a common solvent of PVC and PVA is used as a spinning stock solution, and this solution is placed in a solidification bath containing low-temperature methanol and the like. In the method obtained by cooling gel spinning, drawing, heat treatment as needed, and acetalization, there is a problem that PVC islands are coagulated when the undiluted solution is left due to the low compatibility between PVC and PVC, making spinning difficult. Specifically, PVC that is copolymerized with a monomer having a hydroxyl group is used as the PVC, which makes it difficult for PVC islands to agglomerate and stably produces fibers. In addition, it is possible to obtain fibers with less coloring. Therefore, it is possible to stably produce a PVA-based flame-retardant fiber which is excellent in cost performance and less colored.

The fibers of the present invention can be used in the field of protective clothing such as combat uniforms and firefighting suits, industrial materials such as car seats and vehicle spring receiving materials and air filters, curtains, carpets, blankets,
It can be effectively used for living materials such as futon side sheets, sheet covers, and cotton padding.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Akio Omori 1621 Sazu, Kurashiki City, Okayama Prefecture Kuraray Co., Ltd.

Claims (6)

[Claims] 1. A vinyl alcohol polymer and a vinyl chloride polymer in which a monomer having a hydroxyl group is copolymerized in an amount of 1 to 30% by weight, wherein the vinyl alcohol polymer is a sea component and the vinyl chloride polymer is an island component. Polyvinyl alcohol-based flame-retardant fiber having a sea-island structure. 2. The fiber according to claim 1, wherein a vinyl chloride polymer in which a monomer having a hydroxyl group and a different monomer are copolymerized in an amount of 1 to 15% by weight, respectively. 3. The fiber according to claim 1, wherein the mixing ratio of the vinyl alcohol polymer and the vinyl chloride polymer is from 90:10 to 55:45. 4. A method according to claim 1, wherein the tin compound and / or the antimony compound are used alone or in a mixture with respect to the total weight of the polymer.
The fiber according to any one of claims 1 to 3, wherein the content of the fiber is from 15 to 15% by weight. 5. A solidifying bath in which a vinyl alcohol-based polymer and a vinyl chloride-based polymer are dissolved in a common solvent, and the obtained spinning dope is mixed with a solidifying solvent having a solidifying ability for the vinyl alcohol-based polymer and a stock solution solvent. Wet or dry-wet spinning, extraction, drying, drawing, and, if necessary, heat treatment or acetalization to produce a polyvinyl alcohol-based flame-retardant fiber, satisfying the following conditions (1) to (2). A method for producing a polyvinyl alcohol-based flame-retardant fiber. (1) Use a vinyl chloride-based polymer in which a monomer having a hydroxyl group is copolymerized as a vinyl chloride-based polymer in an amount of 1 to 30% by weight, (2) The spinning solution is a vinyl chloride-based polymer in a vinyl alcohol-based polymer solution. Consisting of a solution of
It has a phase structure in which islands having a particle diameter of 1 to 50 μm are present, and the island diameter change rate of the vinyl chloride polymer solution is 0 to 1 μm /
hr 6. The method according to claim 5, wherein the spinning dope contains 0.1 to 15% by weight of tin compound and / or antimony compound dispersed or mixed with respect to the total weight of the polymer.