JPS58144110A - Synthetic fiber of polyvinyl alcohol and its production - Google Patents

Abstract

PURPOSE:An aqueous solution of a modified polyvinyl alcohol containing copolymerization units with crosslinkable groups in their molecules is spun, drawn and heat set to produce the titled fiber with high resistance to hot water, thus being suitable for use in industrial and cloth purposes, because it becomes insoluble by crosslinking treatment. CONSTITUTION:Only a modified polyvinyl alcohol containing copolymerization units bearing crosslinkable groups of the formula (R<1> is H, lower alkyl; R<2> is alkyl) in the molecule or a combination thereof with an unmodified polyvinyl alcohol is made into an aqueous solution of 10-50wt% concentration. The resultant solution is subjected to wet or dry spinning, drawn and heat treated to give fibers insolubilized by crosslinking. As a modified polyvinyl alcohol, is used preferably a saponified product of a copolymer from N-methoxymethyl acrylamide and vinyl acetate.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a polyvinyl alcohol synthetic fiber having a high degree of hot water resistance and a method for producing the same.

Synthetic fibers obtained from polyvinyl alcohol have conventionally been known as vinylon, and have excellent properties such as high strength, heat resistance, and chemical resistance, and are widely used, especially in industrial material applications. Since the raw material polyvinyl alcohol (hereinafter abbreviated as PTA) is a water-soluble polymer, the fibers simply spun from it are also water-soluble, and are resistant to this (heat treatment and formalin, etc. It is well known that acetalization treatment is carried out.

If sufficient hot water resistance could be obtained without acetalization treatment, the manufacturing process for vinylon could be shortened, which would have great industrial significance. For this purpose, a method of incorporating a crosslinking group into PVA has been considered, and conventionally, vinyl acetate and 7
By copolymerizing solidane diacetate and saponifying this, PVA with aldehyde groups is synthesized, and the production of vinylon from this is also being considered (F
, F. Izard.

Ind, and Eng, C! hem,, 42.2
110 (1950), Masatoshi Ishii, Sengaku Shi, 18, 251
(1962)]. However, since an aqueous solution of modified PVA having an aldehyde group is unstable and tends to form a gel-like state, it is difficult to stably spin the solution, and it has not yet been practically adopted.

As a result of extensive research into methods for stably introducing crosslinking groups into PVA, the inventors of the present invention have determined that a copolymer of vinyl acetate and N-alkoxymethyl (meth)acrylamide monomers has been saponified. The following general formula (I) 1 ■ +C112C+(I) 00NilC11,0-R2 (where R1 is a hydrogen atom or a lower alkyl group, BM
means an alkyl group. ) The modified polyvinyl alcohol containing the copolymerized units shown in ( ) has excellent water solubility in itself and is stable even in highly concentrated aqueous solutions, and by spinning it and subjecting it to heat treatment, vinylon with a high degree of hot water resistance can be obtained. After confirming this, the present invention was completed.

The modified PVA that is the raw material for the synthetic fiber of the present invention is composed of a vinyl ester, especially vinyl acetate, and a compound of the formula CH,=(3R'-
Monomers represented by 0-R" (where 1 is a hydrogen atom or a lower alkyl group, and V is an alkyl group), especially R
Radical polymerization of N-alkoxymethyl (meth)acrylamide in which 1 is a hydrogen atom or a methyl group and 2 is an alkyl group having 1 to 4 carbon atoms, particularly preferably N-methoxymethylacrylamide or Nn-butoxymethylacrylamide. Copolymerization is carried out using an initiator, and then an alcohol solution of this copolymer and an alkali catalyst are applied to partially or highly saponify the vinyl ester units in the coelectropolymer! It is produced by converting it into vinyl alcohol units.

As the vinyl ester that can be used in producing this copolymer, any vinyl ester that becomes vinyl alcohol by saponification after copolymerization can be used, but vinyl acetate is preferred from an economical standpoint.

The aforementioned Shita-style CH! Specific examples of the monomer represented by =CR1-coNIII20-v (凰1ha hydrogen atom or lower alkyl group, R2 is an alkyl group) include tomethoxymethylacrylamide, N-methoxymethylmethacryl(do, toethoxy Methylacrylamide, N-ethoxymethylmethacrylamide, N-togropoxymethylacrylamide, N-n-propoxymethylmethacrylamide, N-isopropoxymethylacrylamide, N-isopropoxymethylmethacrylamide, N-topoxymethylacrylamide, N-n-butoxymethylmethacrylamide, N-isobutoxymethylacrylamide, N
-isobutoxymethyl methacrylamide, N-tert
-butoxymethylacrylamide, N-tert-butoxymethylmethacrylamide, among which N-
Methoxymethyl, tylacrylamide and N-n-butoxymethylacrylamide are particularly preferred in terms of effectiveness and economy. These monomers are well known, for example in British Patent No. 955,420, a copolymer with vinyl acetate and acrylic ester is shown, but N-flufoxydimethyl (meth) A saponified copolymer produced by saponifying a copolymer of acrylamide and vinyl ester and its usefulness are not known.

The saponified product of the copolymer of N-alkoxymethyl (meth)acrylamide and vinyl ester mentioned above and its specific production method have been developed by the present inventors and have already been published in Japanese Patent Applications No. 56-176024 and No. 56-178594. Although a patent application has been filed, the modified PVA used for the purpose of the present invention usually has a content of N-algoxymethyl (meth)acrylamide monomer units of 0.0.
Contains 5 to 10 mol%, preferably 0.1 to 5 mol%, of polyhinyl alcohol units. , 95-70 mol%, the content of vinyl ester units is preferably 0-29 mol%, the degree of polymerization is 500-2500, preferably 1000-2000, the saponification degree of vinyl ester units is 70-100, Preferably, 95 to 100 mol% is used. #LN-alkoxymethyl (meth)
If the content of acrylamide units is less than 0.05 mol%, it is insufficient in terms of hot water resistance, and if it is more than 10 mol%, the production of modified PVA becomes difficult and expensive, which is not preferable.

The N-alkoxymethyl (meth)acrylamide unit in the modified i'v membrane is characterized in that after spinning the modified rv membrane, a crosslinking reaction occurs mainly through heat treatment, and the fiber obtained as a result of this crosslinking reaction. It is considered that a high degree of hot water resistance can be obtained. The amount of crosslinkable groups necessary to provide this performance is determined by the heat treatment conditions, system pH and spinning, as described below.
Although it varies depending on the stretching conditions, it is usually 0.0 as shown above.
It is selected from the range of 5 to 10 mol%, preferably 0.1 to 5 mol%.

This modified PVA is heated and dissolved in water and adjusted to a 10 to 50% by weight aqueous solution in the same manner as in the production of ordinary vinylon fines, and used as a spinning dope. The concentration of the rvum is usually 10 to 25% by weight in the case of wet spinning, and 25 to 50% by weight in the case of dry spinning. It has also been found that the hot water resistance aimed at by the present invention can be achieved even when ordinary unmodified PVA is mixed and spun for the purpose of controlling the amount of modifying groups during the preparation of this stock solution. In this case, however, it is necessary to ensure that the content of N-alkoxymethyl (meth)acrylamide units in the total PVA including both PV units is at least 0.05 mol % as described above. In addition, for special purposes, carboxyl group-modified PVA copolymerized with maleic acid, fumaric acid, itaconic acid, (meth)acrylic acid or its ester, acrylamide-modified PVA, sulfonic group-modified PV, cationic group-modified PV, hydrophobic Group-modified PTA and the like can also be used together.

In the case of wet spinning, the spinning stock solution is supplied from a nozzle at a concentration of 200 to 450 f according to a known manufacturing method for vinylon fiber.
/l of Glauber's salt solution at a temperature of 50 to 50°C, and is discharged into a coagulation bath in which salts such as zinc sulfate are appropriately mixed, and coagulated to form a thread. The core fibers are then introduced into a higher-temperature sodium sulfate solution, subjected to stretching at an appropriate ratio, and then dried, and the spinning dope is discharged from a nozzle into heated air in accordance with the known method for producing vinylon fibers. The water is then evaporated to form thread. Itoshino is usually 150 after that.
Stretching is carried out at humidity above ℃, and then if necessary
Heat shrink at ~260°C.

The fibers thus obtained were heated as is, i.e. at 200°C.
The above heat treatment easily imparts a high degree of hot water resistance, and the major feature is that it can be used in the same way as conventional vinylon.

By the way, in the present invention, although the crosslinking reaction that imparts hot water resistance is achieved only by heat treatment at 200°C or higher as described above, the crosslinking reaction can proceed more easily if the fiber is placed in an acidic region during spinning or subsequent steps. discovered. Therefore, under such conditions, the above-mentioned high temperature is not necessarily necessary and crosslinking can be carried out at a low temperature. For example, the crosslinking reaction is more likely to occur as the - of the spinning dope is lowered to 6 or less, and the spinning dope may be adjusted, or the pH of the spinning dope may be in the neutral range, and the pH of the spinning bath may be lowered. By treating the fibers with an acidic aqueous solution in the subsequent step, the crosslinking reaction can be effectively induced, and in this case, a humidity of 70° C. or higher is sufficient for the crosslinking reaction.

As a result of heat treatment etc., alkoxymethyl (meth)
Although the details of the chemical structure of the crosslinking reaction of the acrylamide unit are not fully clear, it is thought that the following chemical reaction mainly occurs.

IR" + Ckl, -Ckl +
However, for the purpose of obtaining a higher degree of hot water resistance, acetalization treatment may be performed using formaldehyde, acetaldehyde, benzaldehyde, or the like. Also modified PV
It can also be used in the form of a conjugate fiber containing gum as one component.

The thickness of the fibers can be arbitrary depending on the purpose, and is usually 0.
Selected from 5 to 500 deniers.

The synthetic fibers obtained by the above method have excellent strength and hot water resistance, and therefore have excellent performance suitable for both industrial materials and clothing applications, and have great industrial significance. In addition, in the production of the fibers described above, the fibers obtained without hot drawing or heat treatment can be used as a binder for paper manufacturing, etc., and then heat treated and used as a binder with high hot water resistance.

The present invention will be explained below with reference to Examples.

Example 1 Production of modified PV film In a heating type reaction tank equipped with a stirrer, a molar ratio, a chemical solution charging pump, and a reflux condenser, 1q0 parts of vinyl acetate, 2505 parts of methanol, and 2 parts of N-methoxymethylacrylamide were added.
0 parts, and 1 part of 2,2'-azobisisobutyronitrile
After charging 4 parts, the inside of the system was replaced with nitrogen gas, and the temperature inside the machine was raised to 62°C to start polymerization. During a period of 110 minutes, 149 parts of N-methoxymethylacrylamide was dripped into the polymerization system from a chemical feed pump depending on the solid content concentration of the polymerization system. The solid content concentration in the system at the time of termination of polymerization was 47.7%.

This polymerization liquid was charged into a distillation column, and methanol vapor was introduced from the bottom of the column to distill off unreacted vinyl acetate.
A 3N% methanol solution of the copolymer was obtained. This solution 14
While stirring 730 parts at 40° C., 1150 parts of 1N caustic soda methanol solution was added thereto, and after thorough mixing, the mixture was allowed to stand. The whole gelatinized after 4 minutes and 20 seconds. After standing for another 20 minutes, the gel was pulverized using a pulverizer, washed with methanol and ethanol, and then rolled to obtain a white polymer powder. This copolymer had excellent solubility in water. From nuclear magnetic resonance analysis and neutralization titration of this copolymer, it was confirmed that it contained 2.0 mol% of N-methoxymethylacrylamide units, and the degree of saponification of vinyl acetate units was 99.6 mol%, Furthermore, the average degree of polymerization determined by gel permeation chromatography was 1,780.

Production of fiber The modified PVA produced above was made into a 16% aqueous solution as a spinning stock solution, which was fed using a metering gear pump while being maintained at 90°C, and saturated from a metal plate with 200 holes with a hole diameter of O, OS ■φ. Glauber's salt bath (428f/l.

The fibers were spun into a medium (temperature: 40° C., pH: 5, Q), and a 10th speed: 4.7 s, A+in. Further, the wet stretching was increased to 3.02 times and dried at 160°C, followed by 24
The dry heat wind strength was set to 2.7 times at 0° C., and the total stretching ratio was set to 8.5 times. Further heat treatment was performed at 240°C to obtain synthetic fibers with a fineness of 2.0 denier. The strength and hot water resistance of this fiber are shown in Table 1.

Example 2 N-n-
A copolymer of butoxymethylacrylamide and vinyl acetate is saponified to contain 2.0 mol% of N-n-butoxymethylacrylamide units, and the degree of saponification of vinyl acetate units is 99.8 mol%, on average. Modified P with a degree of polymerization of 1790
I got Vmu. This modified FVmu and undenatured normal P
Vmu (saponification degree! 9.9 molar form, average degree of polymerization 1780)
A synthetic fiber of 2.0 denier was obtained by spinning, hot drawing, and heat treatment in the same manner as in Example 1, except that the modified FV membrane of Example 1 was used for the same amount of the mixture. The evaluation results are shown in Table 1.

Comparative Example 1.2 In place of the modified PVA used in Example 1, unmodified PV rubber (saponification degree 99.9 mol%, average polymerization degree 1
780) was used, but in the same manner as in Example 1,
A synthetic fiber having a fineness of 2.0 denier was obtained by stretching and heat treatment (Comparative Example 1). This fiber was further treated with formalin under a sulfuric acid acid catalyst to obtain a synthetic fiber with an acetalization degree of SO mol % (Comparative Example 2). The evaluation results of the fibers thus obtained are shown in Table 1.

As can be seen from Table 1, the synthetic fibers of the present invention have excellent hot water resistance even though they are not subjected to acetalization treatment.

Example 3 Similar to the manufacturing method of modified PV human described in Example 1, Nn-
A modified PVA containing 1.0 mol% of butoxymethylacrylamide units, a degree of saponification of vinyl acetate units of 99.7 mol%, and an average degree of polymerization of 1770 was prepared. This degeneration P
V-mu and undenatured normal PV-mu (saponification degree 99.9)
mol%, average degree of polymerization 1780)
% aqueous solution, this was heated to 150°C and extruded into heated air at 180°C through a metal plate (hole diameter: 0.1 wφ, 200 holes) kept at 150°C, and then wound up. This fiber was stretched 1°0 times at 240°C, and
A 6 denier synthetic fiber was obtained by heat treatment at 45°C. The evaluation results are shown in Table 2.

Comparative Example 5 The evaluation results of a 6-denier synthetic fiber obtained in the same manner as ink in Example 3, using only unmodified PV rubber instead of the modified PVA used in Example 3, were evaluated according to Table 2 of Table 2. Indicated.

Table 2 It was revealed that the synthetic fibers of the present invention had an extremely low shrinkage rate in hot water at 100°C, and also had a low dissolution rate even at 120°C.

Patent applicant: Kuraray Co., Ltd. Representative Patent Attorney Ken Honda

Claims (1)

[Scope of Claims] 1) A crosslinkable insolubilizable polyvinyl alcohol synthetic fiber obtained by spinning modified polyvinyl alcohol containing a copolymerized unit having a crosslinkable group represented by the following general formula (I) in its molecule. 1? 0ONilCH,0-R" (Here, V means a hydrogen atom or a lower alkyl group iLl means an alkyl group, respectively.) 2) Modified polyvinyl alcohol is N-methoxymethylacrylamide
゛. Claim 111) A polyvinyl alcohol-based synthetic line m of JE Kiyoshi, which is a saponified product of a copolymer of fact table 5↓- and vinyl acetate. 5) The polyvinyl alcohol synthetic fiber according to claim 1, wherein the modified polyvinyl alcohol is a saponified product of a copolymer of Nn-butoxymethylacrylamide and vinyl acetate. 4) The content of the present alkoxymethyl (meth)acrylamide unit in the modified polyvinyl alcohol is 0.05 to 10
The polyvinyl alcohol fiber according to claims 1) to 3), which is mol%. 5) A modified polyvinyl alcohol containing a copolymerized unit having a crosslinkable group represented by the following general formula (I) in the molecule alone or in combination with the modified polyvinyl alcohol and unmodified polyvinyl alcohol 10-
A method for producing polyvinyl alcohol-based synthetic fibers, in which a 5ON aqueous solution is wet- or dry-spun by a conventional method, stretched, and heat-treated to obtain cross-linked and insolubilized pongee. R′÷an! -,cji (I)00[
H,0-R" (Here, R1 is a hydrogen atom or a lower alkyl group. V means an alkyl group, respectively.) A method for producing a polyvinyl alcohol-based synthetic fiber according to claim 5), which is a saponified product of a polymer. 7) The modified polyvinyl alcohol is a saponified product of a copolymer of Nn-butoxymethylacrylamide and vinyl acetate. 8) The content of N-alkoxymethyl (meth)acrylamide alone in the modified polyvinyl alcohol is o, o!?~
The method for producing polyvinyl alcohol-based synthetic fibers according to claims 5) to 17), wherein the content is 10 mol%. 9) Claims 5) to 8) in which the spun yarn is cross-linked and insolubilized by heating in an acidic region in a step after spinning.
A method for producing polyvinyl alcohol-based synthetic fibers as described in . 10) The method for producing polyvinyl alcohol synthetic fibers according to claims 5) to 8), in which the spun yarn is heated to 200° C. or higher to crosslink and insolubilize it in the steps after spinning.