JPH0227369B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing polyphenylene sulfide, and more particularly to a novel method for producing polyphenylene sulfide that has a high melt viscosity and has few impurities. As a method for producing polyphenylene sulfide,
A method of reacting p-dichlorobenzene with sodium sulfide in an organic aprotic polar solvent such as N-methylpyrrolidone is disclosed in Japanese Patent Publication No. 3368/1983. However, since the polyphenylene sulfide produced by this method has a low molecular weight and melt viscosity, it cannot be extruded into fibers, films, extruded sheets, etc. As an improved polymerization method for obtaining polyphenylene sulfide with a high degree of polymerization,
No. 12240 discloses a method of adding an alkali metal carboxylate as a polymerization aid to the above reaction system. Further, U.S. Patent No. 4,038,260 describes a method of adding an alkali metal sulfonate as a polymerization aid, and JP-A-56-20030 and JP-A-56-20031 describe the former trialkali metal phosphate and the latter phosphonic acid. A method of adding a dialkali metal salt has been proposed. According to these methods, it is necessary to add a polymerization aid such as an alkali metal carboxylate in an equimolar amount to the amount of sodium sulfide; Among the salts, lithium acetate, which is expensive, requires the use of a large amount of sodium benzoate, which results in an increase in the production cost of the polymer, which is industrially disadvantageous. In addition, in order to simplify the removal operation of the polymerization aid in the polymer purification process after the polymerization reaction and reduce processing costs, and to reduce the electrolyte component contained as an impurity in the recovered polymer as much as possible,
In order to maintain excellent electrical properties, it is desirable to reduce the amount of polymerization auxiliary added, but each of the methods described above does not allow the amount to be reduced to the desired extent. In view of the above points, the present inventors have conducted intensive studies on polymerization auxiliaries that have the effect of increasing the degree of polymerization even in small amounts and can provide polymers with few impurities, and as a result, they have arrived at the present invention. That is, the present invention combines an alkali metal sulfide and a polyhaloaromatic compound in an organic amide solvent with at least one selected from the group consisting of alkali metal salts of organic polybasic acids represented by the following general formula R-(X)n. This is a method for producing polyphenylene sulfide with high viscosity and low impurities, which is characterized by carrying out the reaction in the presence of one type of compound. General formula R-(X)n (wherein, R has 1 to 30 carbon atoms
a divalent to tetravalent organic group, X is -COOM and/or -SO ₃ M, where M is an alkali metal selected from lithium, sodium, potassium, rubidium and cesium, and n is an integer of 2 to 4. represents. ) In the present invention, by using a polymerization aid consisting of an alkali metal salt of an organic polybasic acid, polyphenylene sulfide having a higher intrinsic viscosity can be obtained compared to a similar method that does not use the polymerization aid. Moreover, surprisingly, compared to conventional methods using polymerization aids, it is possible to obtain polymers with better color and a lower content of electrolyte components consisting of by-product salt and polymerization aids. The polyhaloaromatic compound used in the method of the present invention is a halogenated aromatic compound having two or more halogen atoms directly bonded to an aromatic nucleus, and specifically, p-dichlorobenzene, m-dichlorobenzene, , o-dichlorobenzene, trichlorobenzene, tetrachlorobenzene, dichloronaphthalene, trichloronaphthalene, dibromobenzene,
Tribromobenzene, dibromnaphthalene, diiodobenzene, triiodobenzene, dichlordiphenyl sulfone, dibromodiphenylsulfone, dichlorobenzophenone, dibrombenzophenone, dichlordiphenyl ether, dibromodiphenyl Ether, dichlordiphenyl sulfide, dibromodiphenyl sulfide, dichlorbiphenyl, dibrombiphenyl,

Compounds represented by the formula (where Y is chlorine, bromine, iodine, R' is an alkyl group, nitro group, phenyl group, alkoxy group, sulfone group, carboxyl group, amino group), etc., and mixtures thereof. can be mentioned. Usually, a dihaloaromatic compound is used as a monomer, but a small amount of a polyhaloaromatic compound having three or more halogen substituents in one molecule may also be used in order to increase the viscosity due to a branched structure. Alkali metal sulfide compounds include lithium sulfide, sodium sulfide, potassium sulfide, rubidium sulfide, cesium sulfide, and mixtures thereof. Such alkali metal sulfide compounds can be used as hydrates and/or aqueous mixtures or in anhydrous form. Alkali metal sulfides can also be derived from alkali metal bisulfides and alkali metal hydroxides. In addition, alkali metal bisulfide, which exists in trace amounts in alkali metal sulfide,
There is no problem in adding a small amount of alkali metal hydroxide to react with the alkali metal thiosulfate. As the organic amide solvent that is the polymerization solvent, N
-Methylpyrrolidone, N-ethylpyrrolidone,
Examples include N,N-dimethylformamide, N,N-dimethylacetamide, N-methylcaprolactam, tetramethylurea, 1,3-dimethyl-2-imidazolidinone, and mixtures thereof, including N-methylpyrrolidone. is particularly preferred. The alkali metal salt of an organic polybasic acid used in the method of the present invention is represented by the above general formula,
R in the formula has 1 carbon number such as aliphatic, aromatic, alicyclic, etc.
-30 di- to tetravalent carboxylic acid or sulfonic acid residue. Specifically, disodium succinate, disodium adipate, disodium isophthalate, disodium terephthalate, disodium benzene disulfonate, disodium toluene dicarboxylate, disodium toluene disulfonate, disodium trimellistate, and pyromellitic acid. Tetrasodium, trisodium tolutrisulfonate, trisodium sulfophthalate, trisodium sulfoisophthalate, disodium sulfobenzoate, trisodium disulfobenzoate, disodium naphthalene dicarboxylate, disodium naphthalene dicarboxylate, trisodium naphthalene tricarboxylate , trisodium naphthalene trisulfonate, disodium biphenyl dicarboxylate, disodium biphenyl disulfonate, disodium diphenyl ether dicarboxylate, disodium diphenyl ether disulfonate, disodium lauryl diphenyl ether disulfonate, etc., and the above compounds. Compounds in which the alkali metal is replaced with any one of lithium, potassium, rubidium, and cesium, and mixtures thereof can be mentioned. These alkali metal salts of organic polybasic acids may be either anhydrous salts or hydrates, and may also be used in the form of an aqueous solution. In addition, such an alkali metal salt is prepared in advance by mixing with a di- to tetravalent polycarboxylic acid and/or a polyvalent sulfonic acid, an alkali metal hydroxide, an alkali metal carbonate, an alkali metal bicarbonate, etc. in an organic amide solvent. may be used in the production of the present invention as a solution obtained by reacting them at a ratio of 1:0.9 to 1.5 (equivalent ratio). By adding the alkali metal salt of the organic polybasic acid mentioned above, the degree of polymerization of polyphenylene sulfide (hereinafter abbreviated as PPS) is increased, and a polymer with good color and relatively free of impurities such as electrolyte components can be obtained. The reason for this is speculated as follows. That is, since the polymerization aid such as the alkali metal salt of the organic polybasic acid is considerably dissolved in the organic amide such as N-methylpyrrolidone under high temperature conditions, the polymerization aid and the organic amide solvent form a mixed solvent system. However, since the mixed solvent system effectively acts to improve the polycondensation activity of the propagating end of the polymer during the polymerization reaction process, the polymerization reaction is accelerated. On the other hand, since the above-mentioned polymerization aid has a salting-out effect, PPS that reaches a certain degree of polymerization during polymerization separates from the solvent system, and as a result,
It is presumed that the decomposition reaction of the polymer that occurs in the high temperature solvent is suppressed and that PPS with a high degree of polymerization can be obtained. At this time, the above polymerization aid has the effect of increasing the degree of polymerization and suppresses side reactions other than polymer growth reactions and polymer decomposition reactions, resulting in no impurities in the PPS produced and a PPS with extremely good color. It will be done. In addition, in order to achieve these favorable effects, the amount of the polymerization auxiliary needed to be added is smaller than that of conventional alkali metal salts of organic acids, and since it has a high solubility in water, the polymer recovery and purification process is easy. It is envisioned that it will be possible to obtain a PPS that can be made simpler and at the same time has a lower content of electrolyte components. These above-mentioned effects are due to the presence of two or more carboxylic acids in one molecule and/or
Alternatively, it may be caused by the structure itself of the alkali metal salt of an organic polybasic acid containing an alkali metal salt of a sulfonic acid. In the method of the present invention, the amount of alkali metal sulfide used is 0.8 in molar ratio to the dihaloaromatic compound.
A suitable range is from 0.9 to 1.2, preferably from 0.9 to 1.1. The amount of the organic amide solvent to be used is in a molar ratio of 2.5 to 20, preferably 3 to 10, relative to the alkali metal sulfide. The amount of the alkali metal salt of the organic polybasic acid used in the present invention is usually preferably in the range of 0.5 to 1.5 in molar ratio to the alkali metal sulfide, but since it is a salt of a polybasic acid, it may be Even if the amount used is within the range of 0.05 to 0.5 in terms of molar ratio, the effects of the present invention can be sufficiently obtained. When carrying out the method of the present invention, an alkali metal sulfide and an alkali metal salt of an organic polybasic acid are added to an organic amide solvent preferably under an inert gas atmosphere at room temperature to 130°C, and the mixture is stirred.
At a temperature of 150 to 230°C, preferably 170 to 210°C, most of the water in the system is driven out of the system under normal pressure. After cooling, the polyhaloaromatic compound is added and the reaction system is heated under pressure at 210 to 290°C, preferably 230 to 280°C, 1 to 200°C.
Allow polymerization to occur for 10 hours. After the reaction is completed, the reaction mixture is filtered in a conventional manner, washed repeatedly with hot deionized water and acetone, and dried.
PPS is obtained. The thus obtained PPS has a high degree of polymerization and has a high melt viscosity without being thickened by thermal crosslinking treatment, so it can be used not only for injection molding but also for extrusion molding and blow molding. Therefore, it is extremely useful for applications such as engineering plastics, films, fibers, etc., which take advantage of the excellent properties inherently possessed by PPS, such as heat resistance, chemical resistance, flame retardance, and electrical properties. In addition, the value of the intrinsic viscosity [η] of the generated PPS is 0.4
At a polymer concentration of g/100ml solution, α-
Measured in chlornaphthalene at 206℃, using the following formula [η]=
This is a value calculated according to ln (relative viscosity value)/polymer concentration. In addition, the content of electrolyte components in the produced polymer can be determined by thermally decomposing the polymer in sulfuric acid containing perchloric acid, measuring the sodium content in the decomposed solution with an atomic absorption spectrophotometer, and calculating the content of sodium chloride. This is a value converted to content. The present invention will be explained below based on examples. Example 1 1 N-methylpyrrolidone in an autoclave
350g and 104.8g (0.8 mol) of sodium sulfide hexahydrate
and disodium phthalate 42.2g (0.20mol)
was charged, and the temperature was gradually raised to 200°C over about 2 hours with stirring under a nitrogen atmosphere, and 21 ml of water was distilled out. After cooling the reaction system to 170°C, 117.6 g (0.80 mol) of p-dichlorobenzene and 80 g of N-methylpyrrolidone were added, and the mixture was heated at 220°C for 2 hours.
The reaction was carried out at 250℃ for 3 hours (the internal pressure at the end of the weight was
6.7Kg/ ^cm2 ). After cooling the reaction vessel, the contents were filtered, and the solid content was washed three times with hot water and twice with acetone, and then dried at 120°C to obtain 79.5 g of off-white granular PPS polymer ( yield 92%). The intrinsic viscosity of the polymer is 0.31 and the salt content is 720ppm
It was hot. Comparative Example 1 This comparative example shows the results obtained when no polymerization aid was added. Polymerization was carried out under the same conditions as in Example 1 except that disodium phthalate was not added. 70.8 g of gray-brown powder polymer was obtained (82% yield). The intrinsic viscosity of the polymer was 0.13, and the salt content was 2100 ppm. Comparative Example 2 This comparative example shows the results obtained when sodium benzoate as a polymerization aid was used in an equimolar amount to sodium sulfide. Polymerization was carried out under the same conditions as in Example 1, except that 115.2 g (0.80 mol) of sodium benzoate was added instead of disodium phthalate. As a result, 76.9 g of pale gray-brown particulate polymer was obtained (yield: 89%). The intrinsic viscosity of the polymer is 0.27, and the salt content
It was 2300ppm. Example 2 117 g (0.8 mol) of p-dichlorobenzene and 0.44 g of 1,2,4-trichlorobenzene were used as monomers to produce a branched, highly viscous PPS.
Polymerization was carried out under the same conditions as in Example 1, except that g (0.3 mol % based on p-dichlorobenzene) was used. 81.0 g of off-white particulate polymer was obtained (94% yield). The intrinsic viscosity of the polymer was 0.37 and the salt content was 750 ppm. Example 3 Polymerization was carried out under the same conditions as in Example 1, except that 42.0 g (0.20 mol) of disodium terephthalate was added instead of disodium phthalate as a polymerization aid. 80.3 g of off-white granular polymer was obtained (93% yield). The intrinsic viscosity of the polymer is 0.30;
The salt content was 820 ppm. Example 4 Instead of disodium phthalate as a polymerization aid, a 30% aqueous solution of trisodium sulfophthalate156
Polymerization was carried out under the same conditions as in Example 1, except that 128 ml of water was distilled out, and the internal pressure at the end of the polymerization was 7.2 Kg/cm ² . 76.0 g of off-white powdery polymer was obtained (88% yield).
The intrinsic viscosity of the polymer is 0.28 and the salt content is
It was 780ppm. Example 5 Polymerization was carried out under the same conditions as in Example 1, except that 241 g (0.20 mol) of a 45% aqueous solution of disodium lauryl diphenyl ether disulfonate was used instead of disodium phthalate as a polymerization aid, and distillation was carried out. The amount of water added was 145ml, and the internal pressure at the end of polymerization was 8.0.
It was Kg/ ^cm2 . 77.7 g of gray granular polymer was obtained (90% yield). The intrinsic viscosity of the polymer is 0.27
The salt content was 920ppm. Example 6 1 N-methylpyrrolidone in an autoclave
350 g and 33.2 g (0.2 mol) of terephthalic acid were charged and heated to 120° C. under a nitrogen atmosphere to form a homogeneous solution. Add 40g of 40% sodium hydroxide solution to this solution.
(0.4 mol) was added dropwise over 30 minutes at a temperature of 120 to 140℃.
The mixture was stirred for an additional 30 minutes. Next, after adding 104.8 g (0.8 mol) of sodium sulfide di, heptahydrate,
The temperature was gradually raised to 200°C over 2 hours, and 52ml of water was distilled out. The reaction system was cooled to 170°C, and the subsequent polymerization step was carried out under the same conditions as in Example 1. The internal pressure at the end of polymerization was 7.2 Kg/cm ² . Finally
78.6 g of off-white granular PPS polymer was obtained (91% yield). The intrinsic viscosity of the polymer was 0.32, and the salt content was 840 ppm.

Claims (1)

[Scope of Claims] 1. In an organic amide solvent, an alkali metal sulfide and a polyhaloaromatic compound are combined with the general formula R-(X)n (wherein R has 1 to 30 carbon atoms)
a divalent to tetravalent organic group, X is -COOM and/or -SO ₃ M, where M is an alkali metal selected from lithium, sodium, potassium, rubidium and cesium, and n is an integer of 2 to 4. represents. ) A method for producing polyphenylene sulfide, which comprises reacting in the presence of at least one compound selected from the group consisting of alkali metal salts of organic polybasic acids represented by: