JPH0132851B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing polyphenylene sulfide, and more particularly to a method for producing high molecular weight polyphenylene sulfide. Polyphenylene sulfide is produced by the method disclosed in Japanese Patent Publication No. 45-3368. That is, in an organic solvent such as N-methylpyrrolidone, P-
It is produced by reacting dichlorobenzene with sodium sulfide. The polyphenylene sulfide obtained by this method has an extremely low degree of polymerization and is not suitable for use as it is.Industrially, this low degree of polymerization is heated in air and oxidatively crosslinked, and three-dimensional crosslinking is performed to increase the molecular weight. It is used for practical purposes such as injection molding. However, even this high-molecular-weight material had poor extrusion moldability and could not be used for applications such as textile fibers, films, pipes, and sheets. Furthermore, a method for obtaining high molecular weight polyphenylene sulfide through a polymerization reaction is already known. That is, as shown in JP-A-53-136100, JP-A-51-144495, JP-A-51-144497, and JP-A-56-28217, polymerization using an alkali sulfide or a hydrated salt thereof prior to the polymerization step The polymer is polymerized after removing water caused by the auxiliary agent from the system.
For example, according to JP-A-53-136100, prior to the polymerization process, a mixture of 60% sodium sulfide and N-methylpyrrolidone is heated and dehydrated to reduce the amount of water in the polymerization system to 1.0 to 2.4% per mole of sodium sulfide. It is adjusted within the molar range. At this time, various problems occur. First, N-methylpyrrolidone, which is an expensive solvent, evaporates together with water, reducing its recovery rate and increasing costs. Second, hydrogen sulfide, a by-product of sodium sulfide, causes stress corrosion of iron, stainless steel, etc. This tendency increases as the amount of hydration water decreases. For this reason, performing the dehydration process of sodium sulfide in the same polymerization kettle that requires high temperatures and pressures and must be made of stainless steel poses a problem in terms of corrosion, which may affect the durability or safety of the kettle. decrease. Thirdly, because sodium sulfide itself is not thermally stable enough, it decomposes or oxidizes during the dehydration process, disrupting the equivalence balance with polyhaloaromatic compounds, resulting in high molecular weight
PPS cannot be manufactured stably. As a result of extensive research, the present inventors have found that high molecular weight polyphenylene sulfide can be stably obtained by using substantially anhydrous sodium sulfide and sodium sulfite without delicately controlling the water content. They discovered this and arrived at the present invention. That is, the present invention is substantially anhydrous and contains 0.1 to 15% by weight of sodium sulfite and 99.9% sodium sulfide.
Polyphenylene sulfide is produced by reacting a mixture consisting of ~85% by weight with a polyhaloaromatic compound in an organic polar solvent under conditions in which water present in the polymerization system is 0.3 mol or less per 1 mol of sodium sulfide. Provides a method for manufacturing. 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, dichlorodiphenyl sulfone, dibromodiphenylsulfone, dichlorobenzophenone, dibrombenzophenone, dichlordiphenyl ether, dibromodiphenyl Examples include ether, dichlorophenyl sulfide, dibromodiphenyl sulfide, dichlorbiphenyl, dibrombiphenyl, and mixtures thereof. Usually dihaloaromatic compounds are used, preferably p-dichlorobenzene. Incidentally, in order to increase the viscosity of the polymer due to the branched structure, a polyhaloaromatic compound having three or more halogen substituents in one molecule may be used in combination with a small amount of a dihaloaromatic compound. The sulfur source used in the present invention is a mixture of sodium sulfide and sodium sulfite. It is necessary that the sulfur source be substantially anhydrous. In the present invention, a substantially anhydrous mixture of sodium sulfide and sodium sulfite refers to a mixture containing 0.3 mol or less of water of hydration per 1 mol of sodium sulfide. Such mixtures with more than 0.3 mol of water of hydration cannot be used in the present invention.
It should be noted that such a mixture preferably has hydration water of 0.2 mol or less, more preferably 0.1 mol or less. Further, the above mixture consists of 0.1 to 15% by weight of sodium sulfite and 99.9 to 85% by weight of sodium sulfide, and 0.5 to 7% by weight of sodium sulfite.
and 99.5 to 93% by weight of sodium sulfide. Since this mixture contains sodium sulfite, an unexpected effect is exhibited in a polymerization system that contains almost no water. That is, in the polymerization system of the present invention, sodium sulfite produces a base buffering effect, exists near the polymerization active end, activates the polymerization reaction, and prevents the decomposition of the polyphenylene sulfide polymer produced. They are synergistically demonstrated. In the present invention, there are no particular limitations on the method of mixing anhydrous sodium sulfide and sodium sulfite as long as the composition ratio of the resulting mixture is within the range of the present invention. For example, it is sufficient to simply weigh a predetermined amount of anhydrous sodium sulfide and sodium sulfite and mix the two. Alternatively, a mixture may be obtained by partially oxidizing sodium sulfide with oxygen in the air. The organic polar solvent used in the process of the invention should be substantially liquid at the reaction temperature and pressure used. Preferred organic polar solvents include formamide, acetamide, N-methylformamide, N,N-dimethylformamide, N,N-dimethylacetamide, 2-pyrrolidone, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, ε - amides, ureas and lactams such as caprolactam, N-methyl-ε-caprolactam, hexamethylphosphoramide, tetramethylurea, 1,3-dimethyl-2-imidazolidinone; sulfones such as sulfolane and dimethylsulfolane; Nitriles such as benzonitrile;
Examples include ketones such as methyl phenyl ketone and mixtures thereof. Among these solvents, it is particularly preferable to use aprotic organic polar solvents such as amides, lactams, or sulfones. In the present invention, it is necessary that the amount of water present in the polymerization system is 0.3 mol or less, preferably 0.2 mol or less, per 1 mol of sodium sulfide. The moisture is the sum total of all moisture present in the polymerization system, and includes, for example, hydration water of sodium sulfide, hydration water of a polymerization aid, free water, and the like. In addition, moisture
If the amount exceeds 0.3 mol/1 mol of alkali sulfide, it is not preferable because not only is it impossible to increase the molecular weight of polyphenylene sulfide, but also corrosion of stainless steel, iron, and other pot walls occurs. In the production method of the present invention, it is preferable to use various polymerization aids in combination. As the polymerization aid,
It is selected depending on the effect of promoting the polymerization reaction, the effect of preventing decomposition of the polymer during the polymerization reaction and post-treatment steps, and the effect of removing by-product salt present in the polymer. One polymerization aid that can be used in the present invention is lithium halides, including, for example, lithium chloride, lithium bromide, lithium iodide, and mixtures thereof. One of the polymerization aids that can be used in the present invention is an organic carboxylic acid metal salt. The organic group other than the carboxyl group of the organic carboxylic acid metal salt usually has 1 to 50 carbon atoms, and also contains nitrogen, oxygen, halogen,
It may contain silicon and sulfur, and is preferably an alkyl group, a cycloalkyl group, an aryl group, or an alkylaryl group. In addition, the metal atoms of the organic carboxylic acid metal salt are lithium, sodium,
It is selected from potassium, rubidium, cesium, magnesium, calcium, zinc, strontium, cadmium, and barium, with alkali metals being particularly preferred. The organic carboxylic acid metal salt is preferably anhydrous, but if necessary, the water in the polymerization system can be removed in the presence of an organic polar solvent such as N-methylpyrrolidone without adding sodium sulfide prior to the polymerization step. It can also be used after being dehydrated until it falls within the scope of the present invention. Examples of carboxylic acid metal salts that can be used in the method of the present invention include lithium acetate, sodium acetate,
Potassium acetate, lithium propionate, sodium propionate, lithium 2-methylpropionate, rubidium butyrate, lithium valerate, sodium valerate, cesium hexanoate, lithium heptanoate, lithium 2-methyloctoate, potassium dodecanoate, 4- Rubidium ethyl ettradecanoate, sodium octadecanoate, sodium heneicosanoate, lithium cyclohexanecarboxylate, cesium cyclododecanecarboxylate, sodium 3-methylcyclopentanecarboxylate, potassium cyclohexylacetate, potassium benzoate, lithium benzoate, sodium benzoate, Potassium m-toluate, lithium phenyl acetate, sodium 4-phenylcyclohexanecarboxylate, p
- Potassium tolyl acetate, lithium 4-ethylcyclohexyl acetate, dilithium succinate, disodium succinate, dipotassium succinate, dilithium adipate, disodium adipate, dipotassium adipate, dilithium sebacate, disebacate Sodium, dipotassium sebacate, dilithium decanedicarboxylate, disodium decanedicarboxylate, dipotassium decanedicarboxylate, dilithium phthalate, disodium phthalate, dipotassium phthalate, dilithium isophthalate, disodium isophthalate, Dipotassium isophthalate, dilithium terephthalate, disodium terephthalate, dipotassium terephthalate, trilithium trimellitate, trisodium trimellitate,
Tripotassium trimellitate, tetralithium pyromellitate, tetrasodium pyromellitate, tetrapotassium pyromellitate, dilithium toluene dicarboxylate, disodium toluene dicarboxylate, dipotassium toluene dicarboxylate, dilithium naphthalene dicarboxylate, disodium naphthalene dicarboxylate, dipotassium naphthalene dicarboxylate,
Mention may be made of magnesium acetate, calcium acetate, calcium benzoate, other similar salts, and mixtures thereof. One of the polymerization aids that can be used in the present invention is Compound A shown below. Compound A: RO-(CH ₂ CH ₂ O-) _o H (wherein R is an alkyl group having 8 to 60 carbon atoms and/or
Alternatively, it is an aryl group and may contain atoms such as oxygen, sulfur, fluorine, chlorine, and bromine.
n represents an integer from 0 to 500. ) In the above formula, R has 8 to 60 carbon atoms, preferably 8 to 60 carbon atoms.
30 alkyl and/or aryl groups, which may contain atoms such as oxygen, sulfur, fluorine, chlorine, bromine, etc. Examples of R include straight chain alkyl groups such as octyl group, lauryl group, decyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, octadecyl group, docosyl group; 1-methylheptyl group, 2-ethylhexyl group, 1 -methyl-4-ethylhexyl group, 1
- Branched alkyl groups such as methyl-4-ethyloctyl group; ethyl phenyl group, butylphenyl group,
Examples include alkylaryl groups such as hexyl phenyl group, dodecylphenyl group, nonylphenyl group, isooctyl phenyl group, tetrapropylene phenyl group, and vinyl phenyl group; alcohol residues of sorbitan alkyl esters. These compounds can be used alone or in mixtures. In addition, the HLB of such a compound is preferably 0 to 19.5. Here, HLB is a numerical value indicating the balance between hydrophilicity and hydrophobicity, and is defined by the following formula. HLB=molecular weight of (CH ₂ CH ₂ O)n/molecular weight of compound A×20 One of the polymerization aids that can be used in the present invention is compound B shown below. Compound B: (In the formula, R ₁ is an alkylene group having 2 to 4 carbon atoms,
R ₂ is hydrogen or an alkyl group having 1 to 30 carbon atoms and/or an aryl group, and a and m each represent an average degree of polymerization of 1 to 50 and 0 to 90, respectively. ) Examples of R ₁ in the above formula are −CH ₂ CH ₂ −,

[Formula] −(CH ₂ −) ₃ ,

[Formula] −( CH ₂ −) ₄ ,

and mixtures thereof. In addition, examples of _R2 include hydrogen,
Alkyl groups such as methyl group, ethyl group, butyl group, octyl group, nonyl group, dodecyl group, cetyl group, 1-methylheptyl, 2-ethylhexyl, 1-methyl-4-ethyloctyl; ethyl phenyl group, dodecylphenyl group alkylaryl groups such as; and aryl groups such as phenyl group and naphthyl group. Specifically, the compounds represented by the above formula B include polyoxyethylene phenyl formaldehyde condensates, polyoxyethylene methyl phenyl formaldehyde condensates, polyoxyethylene nonylphenyl formaldehyde condensates, and polyoxyethylene cetyl phenyl formaldehyde condensates. polyoxypropylene methylphenyl formaldehyde condensate, polyoxypropylene nonylphenyl formaldehyde condensate, polyoxybutylene phenyl formaldehyde condensate, polyoxybutylene nonylphenyl formaldehyde condensate, phenol formaldehyde condensate,
Examples include nonylphenol formaldehyde condensates and mixtures thereof. The amount of sodium sulfide used in the method of the invention is in a molar ratio relative to the dihaloaromatic compound in the range of 0.8 to 1.2, preferably in the range of 0.9 to 1.1. Further, the amount of the organic polar solvent used is in the range of 2.5 to 20, preferably in the range of 3 to 10, in terms of molar ratio to the alkali metal sulfide. The amount of polymerization aid that can be used in the method of the present invention varies depending on the type of compound used, but is usually 0.01 to 0.01 to
200% by weight, preferably in the range from 0.5 to 100%. In the present invention, it is preferable to carry out the polymerization in the presence of an alkali hydroxide. Examples of alkali hydroxides that can be used include lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, and mixtures thereof.
The amount of alkali hydroxide used is generally 0.008 to 1.8 mol, preferably 0.015 to 1.8 mol, per 1 mol of sodium sulfide.
It is within the range of 0.6 mole. Further, in the present invention, an alkali carbonate salt can be used as a substitute compound for the above-mentioned alkali hydroxide. The amount of alkali carbonate used is generally in the range of 0.004 to 0.9 mol, preferably 0.010 to 0.4 mol, per 1 mol of sodium sulfide. When carrying out the method of the present invention, it is necessary to reduce the water content in the system to within 0.3 mol per mol of sodium sulfide prior to the polymerization step.
If the polymerization solvent or polymerization aid contains water or is a hydrated salt, it is dehydrated within a predetermined amount before introducing sodium sulfide into the system. At this time, if dehydration is performed in the presence of sodium sulfide,
In addition to making dehydration difficult, corrosion of the reaction vessel and decomposition of sodium sulfide occur, and even if the treated material is used for polymerization, a product with a high molecular weight cannot be obtained. The reaction temperature at which polymerization is carried out in the present invention is generally
The temperature is 170°C to 330°C, preferably 190 to 300°C. The pressure should be in a range that maintains the polymerization solvent and the polymerization monomer, the haloaromatic compound, substantially in the liquid phase, generally between normal pressure and 200 Kg/cm ² , preferably between normal pressure and 20 Kg/cm ² . Selected from range. Reaction time varies depending on temperature and pressure, but generally
The period ranges from 10 minutes to about 72 hours, preferably 1
hours to 48 hours. The method of the present invention can be carried out by mixing a polyhaloaromatic compound, a mixture of sodium sulfide and sodium sulfite, a polymerization solvent, and, if necessary, a polymerization aid, and heating the mixture preferably under an inert atmosphere. There is no particular restriction on the order in which the components are mixed, and the above components may be added in small portions or all at once during the polymerization step. The polyphenylene sulfide produced by the process of the invention is separated in conventional manner, for example by filtering the polymer and then washing with water, or by diluting the reaction mixture with water, then filtering and washing with water. Refined. In this case, the polymerization solvent can be recovered from the reaction mixture by distillation prior to washing with water. In addition, it is preferable to blow carbon dioxide during or at the end of the polymerization reaction, which not only prevents the decomposition of polyphenylene sulfide and contributes to increasing the molecular weight of the resulting polymer, but also prevents the decomposition of N-methylpyrrolidone. is also effective. Polyphenylene sulfide produced by the method of the present invention has a significantly higher molecular weight than polyphenylene sulfide produced by conventional production methods, and has a low solution viscosity without the need for crosslinking treatment such as heating in air. Approximately 0.19 or more, melt index at 300℃ and 5kg load is approximately 0.1g/10 minutes to approximately 1000
g/10 minutes, preferably 0.5 g/10 minutes to 500 g/10 minutes
10 minutes with the desired characteristics. In other words, in the method for producing polyphenylene sulfide of the present invention, the crosslinking step, which was conventionally essential, becomes unnecessary. Furthermore, the amount of polymerization aids conventionally required in the production of high molecular weight polyphenylene sulfide can be reduced. The polyphenylene sulfide produced according to the present invention can be used in injection molding or compression molding applications without particular crosslinking. It can also be used for extrusion molding, blow molding, and coating of sheets, films, pipes, tubes, etc. If necessary, it is also suitable to blend the polyphenylene sulfide of the present invention with fillers, pigments, flame retardants, stabilizers, and other polymers. For example, glass fibers can be added to improve mechanical strength and heat resistance. Hereinafter, the method of the present invention will be explained according to examples. The intrinsic viscosity value [η] of polyphenylene sulfide was measured at 206°C in α-chlornaphthalene at a polymer concentration of 0.4 g/100 ml solution.
This is a value calculated according to the formula [η]=ln (relative viscosity)/polymer concentration. In addition, parts and % in examples
is based on weight. Reference Example Sodium sulfide containing 0.1% water (0.0086 mol/1 mol of Na ₂ S) was obtained by a conventional method. This substantially anhydrous sodium sulfide and anhydrous sodium sulfite were mixed to obtain mixtures having various compositions as shown in Table 1.

[Table] Example 1 350 N-methylpyrrolidone in a 1l autoclave
g, Sodium sulfide mixture F64.3g obtained in reference example
(62.4 g (0.8 mol) in terms of pure sodium sulfide) and 0.4 g (0.01 mol) of sodium hydroxide, then adjusted the water content as shown in Table 2, and further added 117.6 g (0.80 mol) of p-dichlorobenzene. A solution consisting of 80 g of N-methylpyrrolidone and N-methylpyrrolidone was added, and the mixture was reacted at 230°C for 1 hour and then at 260°C for 3 hours. The internal pressure at the end of polymerization was 4.0 Kg/cm ² .
As shown in Table 2, the yield and solution viscosity of the obtained polymer are greatly affected by the amount of water in the polymerization system, and the water content in the polymerization system is 0.3 mol/mol _Na2S .
High molecular weight polymers are obtained when the amount is less than 1 mole.

[Table] (Note) Numbers marked with * are for comparison.
Comparative Example 1 350 N-methylpyrrolidone in a 1L autoclave
g and Sankyo Kasei 32% sodium sulfide (9 hydrate)
192.2 g (0.80 mol) and 0.4 sodium hydroxide
g (0.01 mol) and heated at 130℃ under nitrogen atmosphere.
It took about 2 hours to raise the temperature from 200°C to 200°C with stirring, distill a mixture containing 21.6 ml of water with N-methylpyrrolidone, and cool the reaction system to 150°C. 117.6 g (0.80 mol) of dichlorobenzene and 80 g of N-methylpyrrolidone were added. The water content in the system immediately before polymerization was 2.7 mol per mol of sodium sulfide. 230℃ for 1 hour, then 260℃
The reaction was carried out at ℃ for 3 hours. Internal pressure at the end of polymerization is 6.5
It was Kg/ ^cm2 . Table 3 shows the yield, intrinsic viscosity, and degree of corrosion of the inner wall of the autoclave of the polyphenylene sulfide obtained. Further, as shown in Table 3, the same procedure was carried out for systems having various water contents with different dehydration temperatures and dehydration times. Polyphenylene sulfide was also obtained in the same manner except that the dehydration conditions were changed or the raw material sodium sulfide was changed to pentahydrate. The results are also listed in Table 2.

[Table] Example 2 Anhydrous sodium sulfide A, B, obtained in Reference Example
Polyphenylene sulfide was obtained in the same manner as in Example 1, No. 1, except that C, D, E, G, H, and I were used as raw materials. The results are shown in Table 4. From this example, sodium sulfite is 0.1% by weight or more.
It has been found that high molecular weight polyphenylene sulfide can be obtained only when specific anhydrous sodium sulfide containing 15% by weight or less is used.

[Table] (Note) Numbers marked with * are for comparison.
Example 3 Using the sodium sulfide mixture F obtained in Reference Example, Example 1 was carried out in the presence of the polymerization aid listed in Table 5.
Polyphenylene sulfide was synthesized in the same manner as No. 1. The results are also listed in the same table. As can be seen from this example and Comparative Example 2 described below, it is clear that high molecular weight polyphenylene sulfide can be obtained in high yield when anhydrous sodium sulfide within the scope of the present invention is used.

[Table] Comparative Example 2 Comparative Example 1 except that the polymerization aids listed in Table 6 were used.
Polyphenylene sulfide was synthesized in the same manner as No. 1. The results are also listed in the same table.

【table】

Claims (1)

[Claims] 1. A substantially anhydrous mixture consisting of 0.1 to 15% by weight of sodium sulfite and 99.9 to 85% by weight of sodium sulfide and a polyhaloaromatic compound in an organic polar solvent, and the water present in the polymerization system is A method for producing polyphenylene sulfide, characterized in that the reaction is carried out under conditions where the amount is 0.3 mol or less.