JP2002242030A - Method for producing polyvinyl alcohol-based flame retardant fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing an efficient and a high performance polyvinyl alcohol (PVA)-based flame retardant fiber capable of keeping flame retarding effects for a long time and further obtain the fiber and fiber structure obtained by the aforesaid method. SOLUTION: This method for producing a polyvinyl alcohol-based flame retardant fiber is to wet spin or dry spin a dope containing at least a vinyl alcohol-based polymer and an organic solvent into a solidification solution having a solidifying function to the vinyl alcohol-based polymer, subsequently pass the spun filaments at least an extracting process in which the spun filaments are impregnated in an extracting solution for extracting the organic solution constituting the spinning solution and a drying process to obtain the polyvinyl alcohol-based flame retardant polymer. In the method, the extracting solution is an organic solvent-based extracting solution and the fiber is produced by introducing a substituting process in which a substituting solution obtained by dissolving a hardly water soluble flame retardant in the organic solvent is added to the filaments in either process from removal of the solidifying solution to the drying process to produce the fiber.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing an efficient and high-performance polyvinyl alcohol (PVA) -based flame-retardant fiber capable of exhibiting a flame-retardant effect for a long time, and a fiber and a fiber obtained by the method. Related to the structure.

[0002]

2. Description of the Related Art Conventionally, flame-retardant fibers include acrylic fibers and polyester fibers copolymerized with a flame-retardant comonomer, regenerated cellulose fibers into which a flame-retardant agent has been kneaded or reacted, and polymers themselves which are flame-retardant. Certain thermosetting fibers, aramid fibers, cotton and wool post-processed with flame retardant agents are on the market. Acrylic fiber generates cyan gas when burned, polyester fiber melt drip, thermosetting fiber has low fiber strength, aramid fiber is extremely expensive, cotton and wool have post-processing texture hardening and poor washing durability. There is a study for improvement.

[0003] On the other hand, polyvinyl alcohol (PVA) flame retardant fiber has attracted attention as a flame retardant fiber because it has no melt drip and has excellent flame retardancy, high strength and excellent washing durability. Examinations have been made (for example, Japanese Patent Publication No. 37-12920, Japanese Patent Publication No. 49-10823,
No. 51-19494). However, the conventional PVA-based flame-retardant fiber is problematic in that its manufacturing process is complicated. Not only is it a dedicated production line, but also the operation management is very complicated. Required a lot of effort. Therefore, a method of adding a flame retardant in a post-process after the production of the PVA-based fiber was also studied. However, in order to homogenize the flame retardancy of the same fiber and obtain a high-quality fiber, the flame retardant is uniformly applied inside the fiber. However, it is difficult to obtain such high-performance flame-retardant fibers by this method. In other words, even if an attempt is made to impart a flame retardant by post-treatment, it is difficult to allow a sufficient amount of the flame retardant to penetrate into the fiber because the oriented crystallization of the fiber is progressing. Also, to disperse the flame retardant inside the fiber,
When a flame retardant that is soluble in the solvent constituting the spinning stock solution (spinning stock solution solvent) is added to the spinning stock solution, the flame retardant flows out into the solidification bath together with the spinning stock solution solvent to provide a sufficient amount of the flame retardant. Becomes difficult. If a flame retardant insoluble in both the spinning solution and the solidification solution is used, it is possible to suppress the outflow to the solidification bath, but in order to obtain sufficient flame retardancy, it is necessary to add a large amount of the flame retardant to the spinning solution. As a result, nozzle clogging and filter clogging occur, resulting in a remarkable reduction in spinning efficiency, and a decrease in drawability, resulting in deterioration of the mechanical strength and quality of the fiber.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for producing an efficient fiber having an excellent persistence of the flame-retardant effect, and a fiber and a fiber product which are obtained by the method and which have an excellent insect repellent effect. It is in.

[0005]

The present invention provides (1) wet spinning or dry-wet spinning of a spinning solution containing at least a vinyl alcohol polymer and an organic solvent into a solidifying solution having a solidifying ability for the vinyl alcohol polymer. Then, a method of obtaining a polyvinyl alcohol-based flame-retardant fiber by passing at least an extraction step and a drying step of immersing the yarn in an extract for extracting the organic solvent constituting the spinning dope, In addition to using an organic solvent-based extract, a replacement step of applying a replacement liquid obtained by dissolving a poorly water-soluble flame retardant in an organic solvent to any of the steps from the solidification liquid separation to the drying step is introduced. (2) A method for producing a polyvinyl alcohol-based flame-retardant fiber, (2) a solidified liquid, an extract, and an extract (1) using at least methanol. The method for producing a polyvinyl alcohol-based fiber described above, (3) containing at least 3% by mass / fiber of a water-soluble flame-retardant soluble in methanol, and wherein the water-soluble flame-retardant is finely dispersed in the fiber. (4) A fibrous structure using the flame-retardant fiber according to (3).

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, it is necessary to use a vinyl alcohol-based polymer as a polymer constituting a fiber. Since the polymer has no melt drip, has excellent flame retardancy, and has high strength and excellent washing durability, it is possible to obtain a high-performance flame-retardant fiber. The vinyl alcohol-based polymer used in the present invention is not particularly limited.
The polymer having the above is preferably used. Of course, if desired, it may have structural units such as ethylene, vinyl acetate, itaconic acid, vinylamine, acrylamide, vinyl pivalate, maleic anhydride, and a sulfonic acid-containing vinyl compound. However, the higher the crystallinity of the polymer constituting the fiber, the higher the flame retardancy of the fiber. Therefore, a polymer having a vinyl alcohol unit of 95 mol% or more is more preferably used to promote crystallization.

The degree of saponification of the vinyl alcohol polymer is preferably at least 80 mol% from the viewpoints of mechanical performance, heat resistance and flame retardancy. From the viewpoint of increasing the degree of saponification, 95 mol%
Preferably, the content is at least 98 mol%, more preferably at least 99 mol%, furthermore preferably at least 99.8 mol%. Although the degree of polymerization of the polymer is not particularly limited, the degree of polymerization is 500 or more, particularly 1
It is preferably at least 500, and more preferably at most 10,000 from the viewpoint of fiber spinnability.

[0008] The PVA-based fiber of the present invention is a fiber containing a vinyl alcohol-based polymer, and the fiber may contain other polymers or other components as desired.
For example, from the viewpoint of enhancing the flame retardancy of the fiber, the fiber may be produced by using a halogen-containing polymer (PVC) in combination. From the viewpoint of the mechanical performance of the fiber and the persistence of the flame retardant effect, the content of the vinyl alcohol-based polymer is preferably 60% by mass or more / fiber, particularly preferably 80 to 100% by mass / fiber.

In the present invention, it is necessary to use a spinning dope containing at least a vinyl alcohol polymer and an organic solvent. By producing fibers by the method described below using such a spinning dope, it is possible to efficiently obtain homogeneous fibers having a high mechanical performance and dimensional stability and a substantially circular cross-section, and further substantially reducing the flame retardant. It becomes possible to finely disperse the inside of the fiber. Of course, as long as the effects of the present invention are not impaired, the spinning dope may contain additives and polymers other than the vinyl alcohol-based polymer and the organic solvent. Examples of the solvent constituting the spinning stock solution (spinning stock solution solvent) include polar solvents such as dimethylsulfoxide (hereinafter abbreviated as DMSO), dimethylacetamide, dimethylformamide, and N-methylpyrrolidone, and various solvents such as glycerin and ethylene glycol. Polyhydric alcohols, and mixtures thereof with rhodane salts, lithium chloride, calcium chloride, mixtures of swellable metal salts such as zinc chloride, and further, these solvents together, or a mixture of these solvents and water, and the like. A spinning solution is used. In particular, DMSO is most preferable in terms of low-temperature solubility, low toxicity, low corrosion, and the like.

The concentration of the polymer in the spinning solution varies depending on the composition, the degree of polymerization and the solvent, but is generally in the range of 8 to 40% by mass. The liquid temperature at the time of discharging the spinning solution is 50 to 1
In the range of 50 ° C., it is preferable that the spinning solution does not gel, decompose or discolor.

The spinning solution may be discharged from a nozzle to perform wet spinning or dry spinning, and may be discharged to a solidifying solution having a solidifying ability for PVA. In particular, when the spinning solution is discharged from multiple holes, the wet spinning method is more preferable than the dry-wet spinning method from the viewpoint of preventing agglomeration of fibers during discharge. In addition, the wet spinning method is a method of directly discharging a spinning dope from a spinneret to a solidification bath, while the dry-wet spinning method is a method of temporarily spinning a spinning dope from the spinneret into air or an inert gas. It is a method of discharging and then introducing into a solidification bath. The solidification referred to in the present invention means that a spinning dope having fluidity changes to a solid having no fluidity.The solidification is performed without changing the composition of the stock solution and the solidification is performed by changing the composition of the stock solution. And both.

When the constituent solvent of the spinning dope is an organic solvent,
Examples of the solidifying solvent constituting the solidified liquid include alcohols such as methanol (hereinafter abbreviated as methanol), ethanol, propanol and butanol, ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone, and fatty acid esters such as methyl acetate and ethyl acetate. Kind,
Organic solvents such as aromatics such as benzene and toluene, and mixtures of two or more of them, which can be solidified in PVA, are preferred. To achieve uniform mild solidification,
Among them, alcohols such as methanol and ethanol, ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone are preferable, and methanol is most preferable in consideration of the separation property from the solvent constituting the stock spinning solution by DMSO. In order to sufficiently solidify the inside of the fiber, it is preferable to use a mixture of a spinning solution constituent solvent as a solidifying solution, and a mixing mass ratio of a solidifying solvent / a spinning solution constituent solvent of 95/5.
~ 40/60, especially 90/10 ~ 50/50, and even 8
Most preferably, it is 5/15 to 55/45. Further, by mixing the spinning solution constituent solvent with the solidification bath, the solidification ability can be adjusted and the cost of separating and recovering the spinning solution constituent solvent and the solidification solvent can be reduced.

The temperature of the solidification bath is not limited, but is usually -15.
Perform between -30 ° C. From the viewpoint of uniform solidification and energy saving, the solidification bath temperature is set to -5 to 25C, particularly 0 to 20C,
Further, the temperature is preferably 2 to 18 ° C. Whether the temperature of the solidification bath is higher or lower than this temperature range, the tensile strength of the resulting fiber often decreases. If the spinning solution is heated to a high temperature, to keep the solidification bath temperature low,
Preferably, the solidification bath is cooled. From the viewpoint of the mechanical performance of the fiber and the prevention of sticking, 1.5 to 7.0 times, particularly 2.times. In any step from the solidification bath or after the solidification bath separation to the drying step.
It is preferable to perform the wet stretching at a rate of 5 to 5.5 times, and it is preferable to increase the wet stretching ratio within a range in which the fluff does not appear, in order to suppress sticking of the thread. To increase the wet draw ratio,
It is also effective to perform wet stretching in two or more stages.

In the present invention, in order to extract the constituent solvent (organic solvent) of the spinning stock solution, it is necessary to pass through an extraction step of immersing itoshino, which has been separated from the solidification bath, in the extract. At this time, the extract must be an organic solvent-based extract, and by using the extract, the solvent constituting the spinning stock solution can be efficiently extracted, and the flame retardant is substantially reduced to the inside of the fiber in the subsequent substitution step. It can be finely dispersed. The extract may be the same as the solidified solution, and among them, it is preferable to use at least an extract using methanol because it is suitable for extraction of DMSO, which is suitable as a solvent for spinning stock solution. By this extraction step, it is preferable that the amount of the solvent constituting the spinning dope contained in Itoshin is 1% by mass or less, especially 0.1% by mass or less of the mass of Itoshino. The contact time is preferably 5 seconds or more, particularly preferably 15 seconds or more. The extraction step may be performed in multiple stages, that is, using a plurality of baths.

Next, the PVA-based fiber may be produced by drying the yarn. In the present invention, in any of the steps from the solidification liquid separation to the drying step, a poorly water-soluble flame retardant is added to an organic solvent. It is important to introduce a substitution step of applying a substitution liquid obtained by dissolving the compound in a solution. This will be described in detail below.
First, as the flame retardant used in the present invention, it is necessary to use a poorly water-soluble flame retardant that can be dissolved in an organic solvent. Although the water-soluble flame retardant easily penetrates into the interior of the hydrophilic PVA-based fiber, it easily flows out due to washing or rainfall, making it difficult to maintain the flame-retardant effect for a long period of time. Therefore, it is necessary to use a water-insoluble flame retardant (including a water-insoluble flame retardant). In addition, the poorly water-soluble flame retardant referred to in the present invention is 30 ° C.
Is a flame retardant having a dissolution amount of 0 to 1 g in 100 g of water.

However, even when an aqueous dispersion of a water-insoluble flame retardant is applied to Ishino, the flame-retardant cannot easily penetrate into the fiber because the water-insoluble flame retardant is not completely dissolved in water. From the above, in order to finely disperse the water-insoluble flame retardant substantially inside the fiber, it is necessary to provide a solution in which the water-insoluble flame retardant is dissolved in an organic solvent. However,
Since PVA-based fibers have high hydrophilicity and crystal orientation is progressing, it is difficult to sufficiently infiltrate the organic solvent into the inside of the fibers. In addition, when a method of dissolving PVA in water and wet-spinning it into an aqueous solution of an inorganic salt such as sodium sulfate is adopted, it is possible for the yarn to reach the drying step to be swollen with water and oriented crystallization is progressing. However, even if an organic solvent-based replacement liquid is applied, the flame retardant cannot be uniformly dispersed due to low affinity with an organic solvent, and a complicated process is required to achieve the object.

On the other hand, when the PVA-based fiber is produced by the above-mentioned method, if any of the steps from the solidification liquid separation to the drying step, itoshino contains a large amount of an organic solvent,
In addition, since the crystal orientation has not been sufficiently advanced and is in a swollen state, the substitution liquid obtained by dissolving a poorly water-soluble flame retardant in an organic solvent is easily applied to the inside of the fiber. Thus, the desired flame retardant can be finely dispersed substantially inside the fiber. For the same reason, it is also possible to uniformly disperse a flame retardant having a large molecular weight. When the flame retardant is present only in the surface layer of the fiber, the effect of maintaining the flame retardant becomes insufficient, and when the flame retardant is not substantially uniformly dispersed, the fiber performance becomes inhomogeneous. A portion having a weak flame effect is formed, and a sufficient flame retardant effect is not exhibited. By dispersing the flame retardant substantially uniformly in the fiber, it becomes possible to obtain a fiber having excellent flame retardancy and excellent flame retardancy.

Further, in the usual case, a drug which easily enters the yarn tends to easily enter the yarn and at the same time easily exits the yarn (that is, easily bleeds out). The bleed out of the flame retardant can be remarkably suppressed by crystallizing the PVA by drying (hot stretching and heat treatment if desired). From the viewpoint of suppressing bleed-out more efficiently, it is preferable to use a flame retardant that is solid at room temperature. The organic solvent content of Itoshino to be subjected to the replacement process is
From the viewpoint of facilitating substitution, 30% by mass or more / polymer, particularly 50% by mass or more / polymer, and further 75% by mass or more /
It is preferably a polymer, and from the viewpoint of suppressing bleed-out of the flame retardant and inter-fiber sticking during the drying step, the ratio is 300% by mass / polymer, further 250% by mass / polymer, particularly 200% by mass / polymer. Is preferred. As the organic solvent constituting the substitution liquid, the same solvent as the solidification liquid can be suitably used. When the solvent constituting the substitution liquid has substantially the same constitution as the solvent constituting the solidification liquid, the replacement liquid It becomes easier to penetrate. Further, a plurality of solvents may be used in combination, or water may be added as long as the effects of the present invention are not impaired. Since the extraction performance of DMSO, which is suitable as a solvent for the spinning solution, is high and the fibers are more easily swollen, it is preferable to use at least methanol as the extract, and at the same time, the substitution is performed more efficiently. It is preferable to use at least methanol.

The flame retardant used in the present invention is not particularly limited, but from the viewpoint of maintaining excellent washing fastness, it is necessary to use a flame retardant which is hardly water-soluble and can be dissolved in an organic solvent as described above. From the viewpoint of more efficiently dispersing the flame retardant finely into the interior of the fiber, it is preferable to use a flame retardant that can be dissolved in the extraction liquid and the replacement liquid. A flame retardant soluble in water is more preferred. In the case of adding a flame retardant to the spinning solution, there is a problem that if a flame retardant that is soluble in the solidification liquid is used, it hardly flows out in the solidification process and cannot hold a sufficient amount of the flame retardant.
When the method of the present invention is employed, a sufficient amount of the flame retardant can be finely dispersed inside the fiber by using a flame retardant soluble in a solidified liquid, an extract, or the like.

More specifically, for example, phosphate flame retardants (such as triphenyl phosphate, tributyl phosphate, tris (2-ethylhexyl) phosphate), and halogen flame retardants (modified tribromophenol alkylene oxide, tetrabromobisphenol) A and its derivatives), boric acid-based flame retardants and the like can be suitably used. In addition, the flame retardant in the present invention refers to an agent capable of increasing the flame retardancy of a fiber by being blended with a fiber, and includes an agent capable of increasing the flame retardancy of a fiber only when used in combination with another agent. . In the present invention, a plurality of flame retardants may be used in combination. The blending amount of the flame retardant is not particularly limited, but from the viewpoint of securing sufficient flame retardancy, 0.1% by mass or more / fiber, particularly 1% by mass or more / fiber,
Further, it is preferable to blend 5% by mass or more / fiber. However, if the blending amount of the flame retardant is too large, the mechanical performance and quality of the fiber are deteriorated.

The replacement step may be introduced to any stage from the solidification liquid separation to the drying step, and the extraction step and the replacement step may be performed in the same step (same bath). From the viewpoint of efficiently extracting the solvent constituting the spinning stock solution and imparting a flame retardant, the solvent is passed through one or more (preferably 2 to 8) extraction baths, then through the substitution bath, and then directly to the drying step. Is preferred.

In the present invention, as long as the effects of the present invention are not impaired, a flame retardant other than a poorly water-soluble flame retardant soluble in an organic solvent may be used, or a flame retardant may be used in a step other than the replacement step. May be partially provided. For example, it is known that the addition of a tin compound or an antimony compound further improves the flame retardancy of the fiber, particularly when a halogen-based substance is used as the flame retardant or the fiber constituent polymer. Although the flame-retardant mechanism is strictly unclear, tin and antimony react with halogens during combustion, and the reactants tin halide and antimony halide volatilize and generally prevent the radical chain reaction in the oxidation reaction field. It is said that

However, when methanol is used as the solidifying solution, the extracting solution and the replacing solution, it is difficult to apply a tin compound or an antimony compound insoluble in methanol to the fiber by the above-mentioned method. Therefore, in this case, it is preferable to adopt a method of adding a tin compound or an antimony compound to the spinning solution. In general, when a flame retardant is added to a spinning dope, there is a problem that it almost flows out of the fiber in a subsequent solidification step. Since it does not dissolve in both liquids, it can be finely dispersed in the fiber without substantially flowing out into the solidification liquid.

When the method is adopted, if the fiber is manufactured by adding a flame retardant in an amount sufficient to impart the flame retardancy to the spinning solution, the mechanical performance and quality of the fiber are reduced, and the nozzle and filter are clogged. However, in the present invention, a sufficient amount of the flame retardant can be applied in the replacement step, so that it is not necessary to add a sufficient amount of the flame retardant to the spinning solution so that the fiber performance is impaired. Fibers having excellent flame retardancy can be obtained. From the viewpoint of ensuring the mechanical performance and spinnability of the fiber, the amount of the flame retardant added to the spinning dope should be 8
% By mass / fiber, particularly preferably 6% by mass or less / fiber, more preferably 0% by mass or more / fiber, particularly preferably 0.1% by mass or more / fiber.

The tin compound referred to in the present invention is not particularly limited as long as it is a compound containing tin element. However, in view of the effect of enhancing flame retardancy as a flame retardant aid and cost performance, inorganic compounds such as tin oxide and metastannic acid are used. Oxides are preferred. 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. The halogen content is preferably 5% by mass or less / fiber, particularly preferably 1% by mass / fiber in terms of environmental friendliness and easy disposal, and the halogen content was determined by placing the sample (Amg) in an oxygen stream. This gas is contacted with a platinum catalyst at 800 ° C. to generate a simple halogen, and then the simple halogen is reacted with heated silver at 400 to 450 ° C., and the mass increase of silver after the reaction (Bmg) And B / A × 100.

After the extraction step and the replacement step, the itoshino may be introduced to the drying step. At this time, an oil agent or the like may be applied as needed and dried. The drying temperature is preferably 210 ° C. or lower, and multistage drying in which drying is carried out at a low temperature of 160 ° C. or less at the beginning of drying and at a high temperature in the latter half is preferred. Further, it is preferable to apply dry heat stretching and, if necessary, dry heat shrinkage to orient and crystallize the PVA molecular chain, thereby enhancing the strength, water resistance and heat resistance of the fiber. In order to enhance the mechanical performance of the fiber, a total draw ratio of 7 under a temperature condition of 150 to 250 ° C.
It is preferable to perform the dry heat stretching so that the draw ratio becomes at least 10 times, especially at least 8 times, and more preferably at least 10 times. In addition, the total stretching ratio referred to in the present invention is a ratio represented by a product of a wet stretching ratio and a dry stretching ratio. In the present invention, steps other than the above-mentioned steps and treatments may be introduced at an arbitrary portion. For example, water resistance and washing durability can be increased by post-treatments such as a crosslinking reaction and a hydrophobic reaction.

According to the method of adding a flame retardant in the replacement step, a fiber in which the flame retardant is substantially uniformly finely dispersed in the fiber can be efficiently obtained. The flame retardant fibers are substantially uniform among the same fibers, and since the flame retardant is not agglomerated, fibers having excellent quality and mechanical performance can be obtained. The term “finely dispersed” as used in the present invention refers to a state in which the flame retardant is dispersed without substantially aggregating in the fiber. The state of dispersion of the flame retardant can be confirmed by microscopic observation of the fiber cross section. It is preferable that the presence of the flame retardant is dispersed to such an extent that it cannot be observed by general engineering microscopic observation. Further, it is also observed with an electron microscope such as a TEM. Those that cannot be performed are more preferable. Specifically, it is more preferable that the maximum diameter of the aggregate formed by aggregating the flame retardant is 0.5 μm or less.

The fineness of the fiber obtained by the present invention is not particularly limited, and for example, a fiber of 0.1 to 10000 dtex, particularly 1 to 1000 dtex can be widely used. The fineness of the fiber may be adjusted according to the nozzle diameter and the draw ratio. Fiber strength is 6 cN / dtex or more, and further 8 cN / dte
It is preferably at least x, especially at least 9 cN / dtex, and the LOI is preferably at least 22, more preferably at least 24, particularly preferably at least 25. ADVANTAGE OF THE INVENTION According to this invention, it is possible to obtain the fiber excellent in both the performance of a flame retardant and a mechanical performance. Since the fiber of the present invention has excellent flame retardancy and high quality, it can be used in any form and for any purpose. For example, cut fiber, filament, spun yarn, string,
The fibers can be used in the form of a rope, fibril, or the like, and the fibers may be used as a fabric, for example, a nonwoven fabric, a woven or knitted fabric, or the like. Of course, a fiber structure (such as a cloth) may be obtained in combination with other fibers. For example, pulp, natural fibers such as cotton, polyester fibers, acrylic fibers, polyamide fibers (nylon, aramid, etc.) may be used in combination with synthetic fibers such as PVA fibers, and these combined fibers are flame-retardant fibers. It may be a non-flame-retardant fiber. If necessary, the fibrous structure of the present invention can be combined with another material, for example, a film, metal, resin or the like.

The fibers and fibrous structures of the present invention can be used in various applications, for example, in the field of clothing (especially in the field of protective clothing) such as protective clothing and firefighting clothing, curtains, carpets, blankets, and the like.
It can be used in all fields such as a futon side, a sheet cover, a living material field such as a cotton pad, a car seat, a vehicle spring receiving material, and an industrial material field such as an air filter. Among them, the fiber of the present invention is less colored and has high quality, so that it can be widely used in the field of clothing and living.

[0030]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited only to the examples. [Flame retardant content mass% / fiber] The fiber was dissolved in DMSO, and the flame retardant in the fiber was quantified by gas chromatography. The phosphorus component was quantified by ICP emission analysis, and the bromine component was quantified by ion chromatography analysis. [Strength cN / dtex] Measured according to JIS L-1013. [Flame retardancy index (LOI value)] Measured according to JIS K-7201.

[Example 1] Degree of polymerization 1750, degree of saponification 9
9.8 mol% of PVA was introduced into DMSO, and dissolved by stirring at 100 rpm at 240 rpm under a nitrogen stream for 10 hours to obtain a spinning dope of 20% by mass of polymer. 100 obtained
The spinning stock solution at a temperature of 1000 ° C. was prepared with 1,000 holes and a hole diameter of 0.08 m.
The mixture was wet-spun through a spinneret having a mass ratio of methanol / DMSO of 70/30 and a temperature of 0 ° C. through a spinneret. Then, 3.5 times wet stretching was performed while extracting DMSO with an extraction bath consisting of methanol at room temperature. Then, after passing through a substitution bath in which 10% by mass of "Pirogard SR-314" (modified tribromophenol alkylene oxide) manufactured by Daiichi Kogyo Seiyaku Co., Ltd. was dissolved, it was dried with hot air at 150C, and dried at 230C. The film was stretched by dry heat twice to obtain a flame-retardant fiber having a single fiber fineness of 2.3 dtex, a strength of 11.6 cN / dtex and an LOI value of 25.
The modified tribromophenolalkylene oxide in this fiber was 6.3% by mass / fiber, and when the state of dispersion of the flame retardant in the fiber was confirmed with a 2,000-fold TEM, the uniformity was such that the presence of the flame retardant could not be confirmed. (The maximum diameter of the agglomerates is estimated to be 0.5 μm or less), and excellent flame retardancy and homogeneity, and excellent flame retardant effect durability (washing durability, etc.) were obtained.

Example 2 Fibers were produced in the same manner as in Example 1 except that a stock solution for spinning was prepared by adding 5% by mass of metastannic acid to PVA. The obtained fiber had a single fiber fineness of 2.6 dtex, a strength of 11.1 cN / dtex, and an LOI value of 2
Nine. The total flame retardant content in this fiber was 11.1% by mass / fiber (4.9% by mass of metastannic acid / fiber, 6.2% by mass of modified tribromophenol alkylene oxide /
Fiber). The obtained fiber had excellent flame retardancy, homogeneity, and persistence of the flame retardant effect (such as washing durability).

Example 3 TP manufactured by Daihachi Chemical Industry Co., Ltd.
Fibers were produced in the same manner as in Example 1 except that a substitution bath in which P (triphenyl phosphate) was dissolved at 20% by mass was used. The obtained fiber had a single fiber fineness of 2.3 dtex and a strength of 1.
1.8 cN / dtex and LOI value was 26.5. The total flame retardant content in this fiber is 16.2% by mass / fiber,
Further, when the dispersion state of the flame retardant in the fiber was confirmed with a TEM of 2000 times, the dispersion was uniform and finely dispersed such that the presence of the flame retardant could not be confirmed (the maximum diameter of the aggregate was estimated to be 0.5 μm or less). It had excellent flame retardancy, homogeneity and durability of the flame retardant effect (washing durability, etc.).

Comparative Example 1 A fiber was produced in the same manner as in Example 1 except that the fiber was not passed through the substitution bath. The obtained fiber had a single fiber fineness of 2.2 dtex, a strength of 12.3 cN / dtex,
The LOI value was 20 and the flame retardancy was poor. [Comparative Example 2] A fiber was produced in the same manner as in Example 1, except that Pyrogard SR-314 was not applied in a substitution bath, and 16% by mass / PVA was added to a spinning dope. The single fiber fineness of the obtained fiber is 2.3 dtex, the strength is 12.1 cN / dtex, and the dispersion state of the flame retardant in the fiber is 2000 times TE.
M, it was confirmed that the particles were uniformly finely dispersed (the maximum diameter of the agglomerates was estimated to be 0.5 μm or less) so that the presence of the flame retardant could not be confirmed. The outflow was severe and the solidification bath turned cloudy in a short time. Therefore, the flame retardant content in the fiber is as low as 3.1% by mass / fiber,
The LOI value was as low as 22.

Comparative Example 3 A fiber was produced in the same manner as in Example 1 except that Pyrogard SR-314 was not added in the replacement step, and then placed in a 200 cm ³ pressure-resistant pot.
A methanol solution in which 10% by weight was dissolved in 14 and the drawn yarn were immersed at a bath ratio of 1:30 and treated at 100 ° C. for 1 hour to try to introduce a flame retardant into the fiber. The cross section of the obtained fiber was not observed by TEM, but the presence of aggregates inside the fiber could not be confirmed. However, the composition analysis by EDX did not confirm the presence of bromine, which is a flame-retardant component. Insufficient introduction of flame retardants into the environment.

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Claims (4)

[Claims] 1. A spinning solution containing at least a vinyl alcohol-based polymer and an organic solvent is wet-spun or dry-wet spun into a solidifying solution having a solidifying ability for the vinyl alcohol-based polymer, and then the organic solvent constituting the spinning solution is dissolved. A method for obtaining a polyvinyl alcohol-based flame-retardant fiber by passing at least an extraction step and a drying step of immersing a thread in an extract for extraction, wherein the extract is an organic solvent-based extract and a solidified liquid In any of the steps from the syneresis to the drying step, a polyvinyl alcohol-based flame retardant characterized by introducing a substitution step of applying a substitution liquid obtained by dissolving a poorly water-soluble flame retardant in an organic solvent to itoshino Fiber manufacturing method. 2. The method for producing a polyvinyl alcohol-based fiber according to claim 1, wherein a solidified solution, an extract, and an extract using at least methanol are used. 3. A flame-retardant flame-retardant which is soluble in methanol.
A polyvinyl alcohol-based flame-retardant fiber, characterized in that the flame-retardant water-soluble flame retardant is finely dispersed in the fiber. 4. A fibrous structure comprising the flame-retardant fiber according to claim 3.