JP2003041428A - Polyvinyl alcohol-based flame-resistant fiber and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyvinyl alcohol-based flame-resistant fiber of high performance, having excellent flame retardance for a long term and excellent in mechanical properties, to provide a method for producing the fiber and to provide a fiber structure using the fiber. SOLUTION: This polyvinyl alcohol-based flame resistant fiber containing a solid flame retardant and a liquid flame retardant each having mutual compatibility, wherein the method for producing the fiber comprises contacting, before the drying step, a polyvinyl alcohol-based gel fiber with an organic solvent solution dissolved the flame retardants to be able to uniformly contain the much flame retardants in the inside of the fiber. Thereby, the flame retardants hardly adhere to the rollers in the fiber making process nevertheless the flame- retardants are much contained in the fiber and powdering phenomena and bleeding-out phenomena are not observed.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a high-performance flame-retardant fiber mainly composed of a polyvinyl alcohol-based polymer (hereinafter abbreviated as PVA), which has a high flame-retardant effect for a long period of time and is excellent in mechanical performance, And a method for producing the same, and a fiber structure in which the fiber is used.

[0002]

2. Description of the Related Art Conventionally, as flame-retardant fibers, acrylic fibers or polyester fibers copolymerized with flame-retardant monomers, regenerated cellulose fibers kneaded or reacted with a flame-retardant agent, and polymers themselves are flame-retardant. Thermosetting fibers, aramid fibers, cotton and wool that have been post-processed with flame-retardant chemicals are on the market. However, in the case of the above acrylic fiber, cyan gas is generated during combustion, in the case of polyester fiber, melt drip occurs, in the case of thermosetting fiber, the fiber strength is low, and in the case of aramid fiber, The fibers themselves are extremely expensive, and in the case of cotton and wool, there are various problems such as texture hardening due to post-processing and poor washing durability, and their improvements have been investigated.

On the other hand, in the case of PVA-based flame-retardant fiber, it has attracted attention as a flame-retardant fiber because it has no melt drip and is excellent in flame-retardant property and has high strength and excellent washing durability. Has been done (for example, Japanese Patent Publication No. 37-129)
20, Japanese Patent Publication No. 49-10823, Japanese Patent Publication No. 5
1-19494, etc.). However, conventional PV
A-type flame-retardant fiber has a problem in that its manufacturing process is complicated, requires a dedicated production line, and is very complicated in operation management. It required production equipment and labor.

As a method for solving such a problem,
A method of adding a flame retardant in a post-process after manufacturing the PVA-based fiber was also studied, but homogenizing the flame retardancy in the same fiber,
In order to obtain high quality fibers, it is necessary to uniformly disperse the flame retardant inside the fibers, but it was difficult to obtain such high performance flame retardant fibers by this method. That is, even if an attempt was made to add a flame retardant by post-treatment, it was difficult to permeate a sufficient amount of the flame retardant into the inside of the fiber because the oriented crystallization of the fiber was completed. As a method of dispersing the flame retardant inside the fiber, a method of adding a flame retardant soluble in the solvent (stock solution solvent) that constitutes the spinning dope to the spinning dope can be considered. It becomes difficult to apply a sufficient amount of flame retardant to the fibers, which will flow out. Although it is possible to suppress the outflow to the solidification bath by using an insoluble flame retardant in both the spinning stock solution and the solidification bath, it is necessary to add a large amount of the flame retardant to the spinning stock solution in order to obtain sufficient flame retardancy. As a result, nozzle clogging and filter clogging occur, spinning efficiency is significantly reduced, and further, drawability is reduced and the mechanical strength and quality of the fiber deteriorate.

Further, the inventors of the present invention solidify the spinning solution.
The PVA before extraction and drying is swollen in the extraction solvent. It is difficult to dissolve in water by contacting it with an organic solvent-based displacement bath in which a poorly water-soluble flame retardant is dissolved at the gel thread stage, followed by drying and hot stretching. It was proposed that a high-performance flame-retardant PVA fiber in which the flame retardant was finely dispersed in the fiber and the PVA molecular chain was also highly oriented and crystallized (Japanese Patent Application No. 2001-42866), but the flame retardancy of the inventive fiber was proposed. When the flame retardant content is increased to further enhance the flame retardant in the solid state, the flame retardant appears on the surface of the fiber and the dusting phenomenon becomes apparent, which significantly deteriorates the processability after drying, while When the flame retardant is liquid, there is a problem that the flame retardant bleeds out and the fibers have a sticky feeling.

[0006]

DISCLOSURE OF THE INVENTION An object of the present invention is to provide a PVA-based flame retardant fiber having a high degree of flame retardancy and high mechanical performance, a method for producing the same, and a fiber product obtained from the fiber. .

[0007]

The present invention provides a solid flame retardant (hereinafter abbreviated as SFR) and a liquid flame retardant (hereinafter L).
Abbreviated as FR), and the following conditions (A) to (C)
(A) SFR and LFR are compatible with each other,
(B) The mass ratio of SFR / LFR is 90/10 to 10/9.
The PVA-based flame-retardant fiber is characterized in that it is in the range of 0 and the total content of (C) SFR and LFR is 10 to 60 mass% with respect to PVA. And, preferably, when SRF and / or LFR is a compound containing a halogen atom, the above-mentioned flame-retardant fiber contains a tin compound and / or an antimony compound in an amount of 1 to 10% by mass relative to PVA.

In the present invention, a spinning dope containing PVA and an organic solvent that dissolves it is wet-spun or dry-wet spun in a solidifying bath having a solidifying ability for PVA, and the solidified yarn obtained is spun. In the method for producing a PVA-based fiber by passing through an extraction step for extracting the solvent of the stock solution from Ishino, and further through a drying step, the liquid constituting the extraction bath used in the following conditions and the extraction step is PVA. It is an organic solvent having a solidifying ability, and in any step from the separation from the solidifying bath to the drying step,
Contacting with a liquid in which a solid flame retardant and a liquid flame retardant are dissolved in an organic solvent having a solidifying ability for PVA,
Is a method for producing a PVA-based flame-retardant fiber. And, it is preferable to use the above method for producing a PVA-based flame-retardant fiber, which uses a liquid having a solidifying ability for PVA and methanol as an organic solvent.

And, the present invention is a fiber structure using the above-mentioned flame-retardant fiber.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION First, in the present invention, it is necessary to use PVA as a polymer constituting fibers. Since the polymer has no melt drip and is excellent in flame retardancy, and also has high strength and excellent washing durability, it is possible to obtain a high performance flame retardant fiber. PVA used in the present invention
Is not particularly limited, but the vinyl alcohol unit is 7
Polymers having 0 mol% or more are preferably used. Of course, if desired, ethylene, vinyl acetate, itaconic acid,
It may have a constitutional unit such as vinylamine, acrylamide, vinyl pivalate, maleic anhydride, or 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 in order to promote crystallization.

The degree of saponification of PVA is preferably 95 mol% or more from the viewpoint of mechanical performance, heat resistance, flame retardancy and the like, and from the viewpoint of promoting oriented crystallization to enhance the flame retardancy of the fiber, etc. The saponification degree is preferably 98 mol% or more, particularly preferably 99 mol% or more, more preferably 99.5 mol% or more, and most preferably 99.8 mol% or more. PVA used
The degree of polymerization is not particularly limited, but the degree of polymerization is 500 or more, particularly 1500 in view of mechanical properties of fibers, hot water resistance and the like.
The above is preferable, and from the viewpoint of fiber spinnability, it is preferably 10,000 or less.

The PVA-based fiber of the present invention is a fiber containing PVA, but the fiber may optionally contain other polymer or other component. For example, from the viewpoint of enhancing the flame retardancy of the fiber, the fiber may be produced by using a halogen-containing polymer such as polyvinyl chloride in combination.

Even if a large amount of a flame retardant is added to achieve a high degree of flame retardancy, it does not cause the problems of dusting, stickiness and bleed-out. Therefore, in the PVA type flame retardant fiber of the present invention, it is used as a flame retardant. It is a very important point that SFR and LFR are used together and all of the following three conditions (A), (B) and (C) are satisfied. That is, first,
(A) SFR and LFR must be compatible with each other. According to the present invention, “compatible with each other” means LFR
SFR dissolves in 10% by mass or more at 25 ° C, and SF
LF even if 10% by mass of LFR is mixed with SFR
R means that SFR is absorbed and SFR maintains a uniform solid state. If SFR and LFR are incompatible,
When used together, each promotes dusting and bleeding out even in small amounts, which is rather an adverse effect. It has been found that only when the solid matter and the liquid matter are compatible with each other and mixed in a predetermined range, it is possible to prevent dusting, stickiness and bleed-out.

The following conditions are (B) SFR / LF
The mass ratio of R needs to be in the range of 90/10 to 10/90. If the SFR is more than 90%, the amount of liquid component is small and the resulting fiber tends to be dusted.
Is less than 10%, the liquid component becomes too much, and the resulting fiber tends to be sticky and bleed out easily. Mass ratio of SFR / LFR is 80/20 to 20/80
Is preferred, and 70/30 to 30/70 is more preferred.

Further, as the next condition, (C) SFR and LF
It is necessary that the total content of R is 10 to 60 mass% with respect to PVA. Total content of flame retardant is 10% by mass
If it is less than the above range, high flame retardancy cannot be obtained, which is unsatisfactory. On the other hand, if the total content of the flame retardant exceeds 60% by mass, it is difficult to suppress the feeling of dusting or stickiness and bleed-out even if the method of the present invention is used. SF
The total amount of R and LFR is preferably in the range of 15 to 40 mass% with respect to PVA.

It is unclear why if the above three conditions (A), (B) and (C) are satisfied, it is possible to suppress both the feeling of dusting and stickiness and bleed-out, but S
It is presumed that LFR is melted into FR to form a kind of solid solution.

Next, the SFR and LFR of the present invention will be described with reference to specific examples. Examples of halogen-containing flame retardants include brominated and chlorinated phenols such as tribromophenol and tetrachlorophenol, adducts of ethylene oxide and propylene oxide, and chlorinated and brominated tetrachlorobisphenol A and tribromobisphenol A. Examples thereof include bisphenols and adducts of ethylene oxide and propylene oxide.
Typical examples of halogen-free phosphorus-containing flame retardants include alkyl phosphates such as liquid tris (2-ethylhexyl) phosphate and solid triphenyl phosphate, and phosphorus-containing compounds such as ethylene oxide and propylene oxide adducts thereof. Can be given as.

The melting point that determines solid state or liquid state can be controlled by the type of base skeleton, the type and number of substituted halogen atoms, the carbon number of the substituted alkyl group, the number of ethylene oxide and propylene oxide added, and the like. For example, if the type and number of the base skeleton and the substituted halogen atom are the same and the number of moles of ethylene oxide added is changed, SFR and LFR satisfying the three conditions of the present invention can be obtained. In addition, the solid state and the liquid state referred to in the present invention refer to the state at 25 ° C.,
A flame-retardant substance having fluidity at 25 ° C. is referred to as LFR, and a flame-retardant substance having no fluidity is referred to as SFR. Further, the flame-retardant substance is a general term for organic substances that make the PVA-based fiber flame-retardant as compared with the case where it is not blended because it is blended with the PVA fiber.

In the fiber of the present invention, the above PVA, SF
The three components of R and LFR are essential, but may contain other components depending on the purpose. For example, SFR and /
Alternatively, when the LFR is a compound containing a halogen atom such as bromine or chlorine, when the PVA fiber contains a tin compound and / or an antimony compound in an amount of 1 to 10% by mass based on PVA, the reaction is generated in the gas phase. Since tin halide or antimony halide inactivates radicals generated by combustion to suppress the oxidation reaction, a synergistic effect is obtained in flame retardancy. It is more preferable that the content of the tin compound and / or the antimony compound is 3 to 8 mass% with respect to PVA.

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 tin oxide and metatin are preferred from the viewpoint of flame retardancy enhancing effect as a flame retardant aid and cost performance. Inorganic oxides such as acids are preferred. Further, the antimony compound in the present invention is not particularly limited as long as it is a compound containing an antimony element, but in terms of flame retardancy enhancing effect and cost performance as a flame retardant aid, such as antimony pentoxide and antimony trioxide. Inorganic oxides are preferred.

In addition to imparting flame retardancy to the fiber of the present invention, a dye or pigment is added for coloring, or a heat deterioration inhibitor, an antioxidant, or a heat deterioration preventing agent for suppressing deterioration due to heat or ultraviolet rays.
An agent such as an ultraviolet shielding agent may be contained, or an oil agent or the like may be contained in order to improve process passability.

Next, a method for producing the fiber of the present invention will be described. At least the above SFR and LF in the PVA fiber
As a method of incorporating the two components of R, in a production method in which an organic solvent-based spinning stock solution of PVA is extruded from a nozzle into a solidification bath, and the stock solution solvent is extracted and dried, in any step before solidification to drying, Introducing a process in which the solution obtained by dissolving SFR and LFR in an organic solvent having a solidifying ability and the thread are brought into contact with each other, whereby a large amount of SFR and L
It was found that FR can be stably contained.
A method in which SFR and LFR are dispersed or dissolved in a spinning dope and then spun can be considered, but since LFR is a liquid organic compound, most of the yarn is solidified even if it is dissolved or dispersed in the dope. It was found that the fluid flows from Shinobu to the solidification bath.

In the method of the present invention, it is necessary to use a spinning dope containing at least PVA and an organic solvent. By producing fibers by the method described below using such a spinning dope, it is possible to efficiently obtain a uniform fiber having a substantially circular cross section with high mechanical performance and dimensional stability.
It becomes possible to finely disperse FR substantially inside the fiber. Of course, as long as the effects of the present invention are not impaired, the stock solution for spinning may contain additives and polymers other than PVA and an organic solvent.

Examples of the organic solvent (stock solution) that dissolves PVA include dimethyl sulfoxide (hereinafter referred to as DMS).
Abbreviated as O), dimethylacetamide, dimethylformamide, polar solvents such as N-methylpyrrolidone and polyhydric alcohols such as glycerin and ethylene glycol, and rhodan salts thereof, lithium chloride, calcium chloride,
Examples include a mixture of swelling metal salts such as zinc chloride, and also a mixture of these solvents, or a mixture of these solvents and water. An organic solvent-based spinning stock solution is used. Above all D
MSO is most preferable in terms of low temperature solubility, low toxicity, low corrosiveness and the like.

The polymer concentration in the spinning dope 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 dope is 50 to 1
The range of 50 ° C. is preferable because the spinning dope does not gel, decompose or discolor.

Wet spinning or dry-wet spinning may be performed by discharging the spinning dope from a nozzle, that is, it may be discharged into a solidifying bath having a solidifying ability for PVA. In particular, when the spinning dope is discharged from many holes, the wet spinning method is preferable to the dry-wet spinning method from the viewpoint of preventing the fibers from sticking to each other during discharging. The wet spinning method is a method in which the spinning dope is discharged directly from the spinneret to the solidification bath, while the dry-wet spinning method is a method in which the spinning dope is once discharged 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 the spinning stock solution having fluidity changes to a solid having no fluidity, and gelation which solidifies without changing the composition of the stock solution and coagulation which solidifies by changing the composition of the stock solution. Including both.

When the undiluted solvent is an organic solvent, examples of the solidifying solvent used in the solidifying bath include alcohols such as methanol, ethanol, propanol and butanol,
Ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone, fatty acid esters such as methyl acetate and ethyl acetate, aromatics such as benzene and toluene, and organic solvents having a solidifying ability for PVA such as a mixture of two or more thereof. Are preferred. To achieve uniform and mild solidification, that is, to obtain high-performance fibers,
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 distillative separability from DMSO as a stock solution solvent.

In order to sufficiently solidify the inside of the fiber, it is preferable to use a mixture of a solidifying solvent and a stock solution as a solidifying bath, and a solidifying solvent / stock solution solvent mixture mass ratio of 95/5.
~ 40/60, especially 90 / 10-50 / 50, more 8
Most preferably, it is 5/15 to 55/45. Therefore, the solidifying bath has a methanol / DMSO ratio of 85/15.
A mixture of ~ 55/45 methanol and DMSO will be most preferred. By mixing the stock solution solvent with the solidifying bath, the solidifying ability can be adjusted and the cost for separating and collecting the stock solution solvent and the solidifying solvent can be reduced.

The temperature of the solidifying bath is not limited, but is usually -15.
It is carried out between ℃ and 30 ℃. From the viewpoint of uniform solidification and energy saving, the solidification bath temperature is -5 ° C to 25 ° C, particularly 0 to 20 ° C.
C., more preferably 2-18.degree. Whether the temperature of the solidifying bath is higher or lower than this temperature range, the tensile strength of the obtained fiber is often lowered. When the spinning dope is heated to a high temperature, it is preferable to cool the solidifying bath in order to keep the solidifying bath temperature within the above range.

From the viewpoint of improving the mechanical performance of the fibers and preventing the fibers from sticking to each other, it is 1.5 to 7.0 times, particularly 2 times in the solidifying bath or in any step from the solidifying bath leaving to the drying step. It is preferable to apply a wet drawing of 0.5 to 5.5 times, and it is particularly preferable to increase the wet drawing ratio as much as possible in a range where no fluff is generated in order to suppress sticking of the thread. In order to increase the wet stretch ratio, it is also effective to perform wet stretching in two or more stages.

In the present invention, in order to extract and remove the undiluted solvent (organic solvent) from the solidified silkworm which has been separated from the solidification bath, it is necessary to pass the extraction step of immersing the silkworm which has been separated from the solidification bath in the extraction bath. is there. At this time, it is necessary to use an organic solvent-based extraction bath as the extraction bath, and by using such an organic solvent-based extraction bath, the stock solution solvent can be efficiently extracted, and the flame retardant is substantially removed in the subsequent step. It can be finely dispersed inside the fiber.

As the extraction bath, the same one as the solidification bath may be used, and among them, it is preferable to use the extraction bath using at least methanol because it is suitable for the extraction of DMSO suitable as the stock solution solvent. By this extraction step, the amount of the undiluted solution solvent contained in Itoshino is 1
The amount is preferably not more than 0.1% by mass, more preferably not more than 0.1% by mass. The contact time is preferably 5 seconds or longer, and particularly preferably 15 seconds or longer. The extraction process may be performed in multiple stages, that is, using a plurality of baths.

Next, the thread is dried to produce a PVA-based fiber. In the present invention, the PVA-based fiber may be produced in any step from after the solidifying bath is removed to the drying step.
On the other hand, it is extremely important for the production of the fiber of the present invention to bring the yarn into contact with a liquid obtained by dissolving SFR and LFR in an organic solvent having a solidifying ability. The contacting step will be described in detail below.

First, both the SFR and LFR flame retardants used in the present invention are dissolved in an organic solvent. When SFR and LFR are water-soluble flame retardants, they easily penetrate into the inside of hydrophilic PVA-based fibers, but easily flow out due to washing or rainfall,
It is difficult to maintain the flame retardant effect in the long term, which is not preferable. Both SFR and LFR are 100g of water at 30 ℃
It is preferable that the water-soluble flame retardant has a solubility of 0 to 1 g. In particular, a water-insoluble flame retardant having a solubility in 100 g of water at 90 ° C. of 0.1 g or less is more preferable.

Even when the water dispersion obtained by dispersing the water-insoluble flame retardant in water is brought into contact with Shinoshino, the water-insoluble flame retardant is not completely dissolved in water and exists in the form of submicron particles or more. Therefore, it cannot easily penetrate into the inside of the gel thread. From the above, in order to finely disperse SFR and LFR substantially inside the fiber, SFR and LFR are dissolved in an organic solvent to form a liquid that exists in a nano-order molecular form, and this is brought into contact with the fiber. There is a need.

Further, since the PVA-based fiber has high hydrophilicity and crystal orientation is progressing, it is difficult to sufficiently permeate the organic solvent into the inside of the fiber. When the conventional method for producing PVA fibers obtained by dissolving PVA in water and wet spinning in an aqueous solution of an inorganic salt such as Glauber's salt is used, the yarns up to the drying step are hydrated and swollen. Although crystallization has not progressed, it is not possible to uniformly disperse the flame retardant inside the fiber even if it is brought into contact with an organic solvent-based liquid because of its low affinity with an organic solvent, in order to achieve the purpose. A complicated process is required.

On the other hand, when the PVA-based fiber is produced by the above-mentioned method, in any of the steps from the solidifying bath leaving to the drying step, Itoshino contains a large amount of organic solvent (methanol, etc.). Moreover, since the crystal orientation of PVA is in a swollen state which has not yet progressed sufficiently, by dissolving the water-insoluble flame retardant in an organic solvent and bringing it into contact with a liquid in which the flame retardant is present in nano-order. The liquid easily penetrates into the fibers, and thus the desired flame retardant can be substantially finely dispersed into the fibers. For the same reason, it is also possible to uniformly disperse the flame retardant having a large molecular weight.

When the flame retardant is present only in the surface layer of the fiber, the sustaining effect of the flame retardant becomes insufficient, and when the flame retardant is not dispersed substantially uniformly, the fiber performance becomes heterogeneous. Therefore, a portion having a weak flame retardant effect is formed, and a sufficient flame retardant effect cannot be obtained. By dispersing a large amount of the flame retardant in the fiber substantially uniformly, it becomes possible to obtain a fiber having excellent flame retardancy and durability of the flame retardancy.

Further, in a usual case, a drug that easily enters the yarn tends to easily enter the yarn and at the same time easily exit from the yarn (that is, easily bleed out). By post-drying and hot drawing (heat treatment if desired) to orient and crystallize PVA, diffusion of the flame retardant in the fiber can be significantly suppressed. From the viewpoint of more efficiently suppressing the diffusion in the fiber, it is preferable to use a flame retardant that is solid at room temperature, but if it is attempted to add only a large amount of the flame retardant that is solid at room temperature, the roller after application, especially the drying roller. A large amount of the flame retardant adheres to a heat drawing roller or the like, resulting in poor processability, and the fibers are in a dusty state, which is inconvenient.

The content of the organic solvent of Itoshino (an organic solvent having a solidifying ability for PVA, typically methanol) when contacted with a liquid of an organic solvent containing a flame retardant is From the viewpoint of facilitating penetration into the fiber, it is preferably 30 mass% or more / polymer, particularly 50 mass% or more / polymer, and further 75 mass% or more / polymer, which suppresses interfiber sticking during the drying step. From the above, 300 mass% or less / polymer, further 250 mass% or less / polymer, particularly 200 mass% or less / polymer is preferable.

As the organic solvent used by dissolving the flame-retardant substance, the same ones as the solidifying solvent and the extracting solvent can be preferably used, and when substantially the same solvent as the solvent for the extracting bath is used. It is preferable because the flame-retardant substance can more easily penetrate into the thread. Further, a plurality of solvents may be used in combination, or water may be added within a range that does not impair the effects of the present invention. It is preferable to use at least methanol as the extraction bath because it has a high extraction performance of DMSO suitable as a stock solution solvent, and at the same time, the flame-retardant substance is more efficiently permeated into the fiber. It is preferable to use methanol as at least one component of the organic solvent.

As the flame retardant used in the present invention, it is necessary to use a flame retardant which is poorly water-soluble and soluble in an organic solvent, as described above, from the viewpoint of retaining excellent washing fastness. From the viewpoint of finely dispersing the flame-retardant substance into the fiber more efficiently, it is preferable to use a common organic solvent as the solvent for the extraction bath and the flame-retardant substance, particularly the solidification bath, the extraction bath and the flame-retardant substance. It is preferable to use methanol as the solvent, and therefore, a flame-retardant substance soluble in methanol is more preferable as the flame-retardant substance.

In the case of the method of adding the flame retardant to the spinning dope,
When a flame retardant that can be dissolved in the solidification bath is used, there is a problem in that it hardly flows out in the solidification step and a sufficient amount of flame retardant cannot be retained, but when the method of the present invention is adopted, it is soluble in the solidification bath / extraction bath. By using the flame retardant, it becomes possible to penetrate a sufficient amount of the flame retardant into the inside of the fiber.

In the present invention, the SFR and LFR of the flame retardant
The compounding amounts and specific examples are as described above, but when using a liquid in which these flame retardants are dissolved in an organic solvent, the concentration of each of SFR and LFR in the liquid is 5 to 30.
Mass% and total concentration of SFR and LFR is 1
0 to 50 mass% is preferable. When the concentration of one of the flame retardants is less than 5% by mass or the concentration of the total flame retardant is less than 10% by mass, the amount of the flame retardant applied is insufficient, and conversely one flame retardant is 30% or less. When the content exceeds 50% by mass or the total concentration exceeds 50% by mass, the flame retardant adheres to the rollers after the drying roller too much, resulting in poor processability.

The step of applying the flame retardant may be introduced at any time after the solidifying bath is removed from the bath to the drying step, and the extraction step and the flame retardant applying step may be performed in the same step (same bath). . From the viewpoint of efficiently extracting the undiluted solution solvent and imparting the flame retardant, pass the flame retardant imparting bath after passing through one or more (preferably 2 to 8) extraction baths, and then directly to the drying step. It is preferable to lead to

In the present invention, as long as the effect of the present invention is not impaired, a flame retardant other than the water-insoluble flame retardant soluble in an organic solvent may be used, or in a step other than the step of applying the flame retardant. A part of the flame retardant or a flame retardant aid may be added. For example, it is known that when a halogen-based substance is used as a flame retardant or a fiber constituent polymer, the addition of a tin compound or an antimony compound as a flame retardant aid further improves the flame retardancy of the fiber. Although the flame-retardant mechanism is not exactly clear, tin and antimony react with halogen during combustion, and the tin halide and antimony halide, which are the reactants, volatilize and block the radical chain reaction in the oxidation reaction field. It is said that.

However, when methanol is used as the solidifying bath, the extraction bath and the flame retardant-imparting bath, it is difficult to apply the tin compound or antimony compound insoluble in methanol to the fibers by the above method. Therefore, in this case, it is preferable to adopt a method of adding a tin compound or an antimony compound to the spinning dope. Generally, when a flame retardant is added to a spinning dope, a problem that it almost flows out of the fiber in the subsequent solidification step occurs. However, when DMSO is used as a solvent for the dope, the tin compound and the antimony compound are either the spinning dope or the solidification bath. Since it does not dissolve in the solution, it can be finely dispersed in the fiber without substantially flowing out into the solidification bath by adopting the method of adding it to the spinning dope.

When this method is adopted, when a fiber is produced by adding a flame retardant in an amount sufficient for imparting flame retardancy to a spinning dope, the mechanical performance and quality of the fiber are deteriorated, and nozzles and filters are clogged. However, since it is possible to add a sufficient amount of the flame retardant in the step of applying the flame retardant in the present invention, it is not necessary to add an amount of the flame retardant to the spinning dope to such an extent that the fiber performance is impaired, and thus mechanical A fiber having excellent performance and flame retardancy can be obtained. From the viewpoint of securing the mechanical performance and spinnability of the fiber, the amount of the flame retardant added to the stock solution for spinning is preferably 8% by mass or less / fiber, particularly 6% by mass or less / fiber, and 0.1% by mass is preferable. % Or more / fiber, particularly preferably 1% by mass or more / fiber.

After the extraction process and the flame retardant application process, the thread is guided to the drying process. At this time, if necessary, an oil agent or the like may be applied and dried. The drying temperature is preferably 210 ° C. or lower, and multistage drying in which the drying is performed at a low temperature of 160 ° C. or lower in the initial stage and at a high temperature in the latter stage is preferable.

Further, it is subjected to dry heat drawing and, if necessary, dry heat shrinkage to orient and crystallize the PVA molecular chain to enhance the strength, water resistance and heat resistance of the fiber and suppress the diffusion of the flame retardant in the fiber. Is preferred. In order to improve the mechanical performance of the fiber, it is preferable to perform dry heat drawing under a temperature condition of 150 to 250 ° C. such that the total draw ratio is 7 times or more, particularly 8 times or more, and further 10 times or more. The total draw ratio in the present invention is a ratio represented by the product of the wet draw ratio and the dry heat draw ratio. In the present invention, steps other than the steps and treatments mentioned above may be introduced in any part. For example, water resistance and washing durability of the PVA-based fiber can be enhanced by post-treatment such as a crosslinking reaction and a hydrophobization reaction.

The fiber strength is preferably 4 cN / dtex or more, more preferably 5 cN / dtex or more, especially 7 cN / dtex or more, and the LOI value is preferably 24 or more, further 25 or more, especially 27 or more. According to the present invention, it is possible to obtain fibers excellent in both flame retardant performance and mechanical performance.

Since the fiber of the present invention has a high degree of flame retardancy and a high mechanical performance, it can be used in any form and for any application. For example, it can be used in the form of cut fibers, filaments, spun yarns, cords, ropes, fibrils, etc., and the fibers may be used as a fabric such as a non-woven fabric or a woven or knitted fabric.

Of course, the fiber structure (fabric or the like) may be obtained in combination with other fibers. For example, natural fibers such as pulp and cotton, polyester fibers, acrylic fibers, polyamide fibers (nylon, aramid, etc.), PVA
It may be used in combination with synthetic fibers such as series fibers, and the fibers used in combination may be flame-retardant fibers or non-flame-retardant fibers. Further, if necessary, the fiber structure of the present invention can be compounded with other materials such as a film, a metal and a resin.

The fiber and the fiber structure of the present invention can be used for various purposes, for example, in the field of clothing such as protective clothing and fire fighting clothing (particularly in the field of protective clothing), curtains, carpets, blankets,
It can be used in all fields such as futon side cloth, sheets cover, padding and other living material fields, car seats, vehicle spring receiving materials, air filters and other industrial material fields. Among them, since the fiber of the present invention has little coloring and high mechanical performance, it can be widely used in the fields of clothing and living.

[0055]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited 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] It was measured according to JIS L-1013. [Flame retardancy index (LOI value)] Measured according to JIS K-7201.

[Example 1] Polymerization degree 1750, saponification degree 9
9.8 mol% PVA and metastannic acid having an average particle size of 0.8 μm were added to DMSO and dissolved by stirring under a nitrogen stream at 100 ° C. for 10 hours, and a polymer concentration of 20 mass% and metastannic acid of 5 mass% / PVA were spun. A stock solution was obtained. The resulting spinning dope at 100 ° C. was passed through a spinneret having a hole number of 1000 and a hole diameter of 0.08 mm, and methanol / DMSO in methanol /
Wet spinning was performed in a solidification bath having a DMSO mass ratio of 70/30 and a temperature of 5 ° C. Then, a 3.5-fold wet drawing was performed while extracting DMSO in an extraction bath composed of methanol at room temperature. The amount of methanol contained in this wet drawn fiber is PV
It was 140% of the weight of A. Then 2 as SFR
"Piroguard SR" manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., which is solid at 5 ° C
-324 "(modified tribromophenol alkylene oxide) and LFR as a liquid at 25 ° C. as PFROGARD SR-414 (modified tribromophenol alkylene oxide) 17 manufactured by Daiichi Kogyo Seiyaku Co., Ltd. 17
After contacting it with a bath in which 1% by mass was dissolved in methanol for 80 seconds, it was dried with hot air at 150 ° C. and subjected to dry heat stretching 4 times at 230 ° C. Adhesion of the flame retardant was not seen so much on the drying roller and the stretching roller.

Single fiber fineness 2.8 dtex, strength 7.6 c
A flame-retardant fiber having N / dtex and LOI value of 29 was obtained. The amount of modified tribromophenol alkylene oxide in this fiber was 28% by mass / fiber (SFR: 10.4% by mass, LFR: 17.6% by mass), and the dispersion state of the flame retardant in the fiber was 2000 times. It was confirmed by TEM that the presence of flame retardant could not be confirmed evenly and finely dispersed (the maximum diameter of agglomerates was estimated to be 0.5 μm or less), and the flame retardant was contained in a large amount. No bleed out was observed, and it had excellent flame retardancy and homogeneity, and flame retardant effect persistence (washing durability, etc.). The SFR and LFR used in this example are compatible with each other.

Example 2 The same spinning dope was prepared as in Example 1 except that metastannic acid was not added, and spinning, extraction and wet drawing were carried out in the same manner as in Example 1. Then SFR
After contacting with 10% by mass of TPP (triphenyl phosphate) manufactured by Daihachi Chemical Industry Co., Ltd. and 14% by mass of TOP [tris (2-ethylhexyl) phosphate] as LFR in a bath dissolved in methanol for 80 seconds,
It was dried with hot air at 150 ° C. and subjected to 4.2 times dry heat drawing at 225 ° C. Adhesion of the flame retardant was not seen so much on the drying roller and the stretching roller.

The single fiber fineness of the obtained fiber is 2.5 dte.
x, the intensity was 7.1 cN / dtex, and the LOI value was 26. The total content of TPP and TOP in this fiber is 2
8% by mass / fiber (SFR: 11.7% by mass, LFR: 1
The content of the flame retardant was 6.3% by mass, and the dispersion state of the flame retardant in the fiber was confirmed by TEM at 2000 times. As a result, the flame retardant was uniformly finely dispersed (the maximum diameter of the aggregate was 0.5 μm). It is presumed to be the following), and bleed-out is not seen despite containing a large amount of flame retardant, excellent flame retardancy and homogeneity, flame retardant effect persistence (washing durability, etc.)
It was something that had. The SF used in this example
R and LFR are compatible with each other.

[Comparative Example 1] In Example 1, instead of Pyroguard SR-324 as the SFR, a base skeleton different from Pyroguard and having no compatibility with Pyroguard SR-414, Fireguard 2000 (Tetrabromobisphenol) manufactured by Teijin Kasei An attempt was made to obtain a PVA-based flame-retardant fiber in the same manner as in Example 1 except that A) was used. However, the compatibility between them was poor and a uniform bath could not be obtained. Therefore, the insoluble component was removed by a filter and a uniform solution was used as a replacement bath, but a large amount of the flame retardant was attached to the drying roller and the stretching roller, and long-time sampling was not possible. Further, the obtained sample was observed to have a bleed-out phenomenon as well as a dusting phenomenon, and it was not a normal fiber.

Comparative Example 2 TO of LFR in Example 2
P is not used, only SFR TPP is added to methanol 24
An attempt was made to prepare fibers in the same manner as in Example 2 except that a bath having a mass% dissolved therein was used. The bath was a uniform transparent liquid, but the flame retardant gummed up on the drying roller and stretching roller and a large amount of it adhered, and the fiber wiped phenomenon was observed, resulting in processability.
The appearance of the fiber was poor.

[0062]

According to the present invention, a high-performance PVA-based flame-retardant fiber having a high flame-retardant effect for a long period of time and having excellent mechanical performance can be obtained. Further, the PVA-based flame-retardant fiber of the present invention is Even if the flame retardant is contained in a large amount, the flame retardant is less likely to adhere to the roller during the fiber manufacturing process, and there is an advantage that the dusting phenomenon and the bleed-out phenomenon are not observed. From the above, the flame-retardant fiber of the related art can be suitably used for the fabric fiber structure, and the fiber structure can be used for many of the above-mentioned application fields.

Claims (5)

[Claims] 1. A solid flame retardant and a liquid flame retardant are contained, and the following conditions (A) to (C) (A) the solid flame retardant and the liquid flame retardant are compatible with each other, and (B). Mass ratio of solid flame retardant / liquid flame retardant is 90/10 to 10/90
And (C) the total content of the solid flame retardant and the liquid flame retardant is 10 to 60 mass% with respect to the polyvinyl alcohol-based polymer. Flame retardant fiber. 2. When the solid flame retardant and / or the liquid flame retardant is a compound containing a halogen atom, the tin compound and / or the antimony compound is contained in an amount of 1 to 10% by mass based on the polyvinyl alcohol polymer. The flame retardant fiber according to claim 1. 3. A solidified yarn obtained by wet spinning or dry wet spinning a spinning stock solution containing a polyvinyl alcohol-based polymer and an organic solvent capable of dissolving the polyvinyl alcohol-based polymer in a solidifying bath having a solidifying ability with respect to the polyvinyl alcohol-based polymer. In the method for producing a polyvinyl alcohol fiber by passing through an extraction step for extracting the solvent of the spinning dope from the Shinoshino, and further through a drying step, the following conditions and the extraction bath used in the extraction step is constituted. The liquid to be used is an organic solvent having a solidifying ability for the polyvinyl alcohol-based polymer, and in any step from the separation from the solidifying bath to the drying step, the thread is solidified for the polyvinyl alcohol-based polymer. Is brought into contact with a liquid in which a solid flame retardant and a liquid flame retardant are dissolved in an organic solvent having Preparation of polyvinyl alcohol-based flame retardant fibers. 4. The method for producing a polyvinyl alcohol-based flame-retardant fiber according to claim 3, wherein methanol is used as the organic solvent and the liquid having a solidifying ability with respect to the polyvinyl alcohol-based polymer. 5. A fiber structure in which the flame-retardant fiber according to claim 1 or 2 is used.