JPH0352774B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing poly-p-phenylene sulfide, and more particularly to a method for producing high-viscosity poly-p-phenylene sulfide that can be melt-molded. A method for producing poly-p-phenylene sulfide by reacting p-dichlorobenzene and sodium sulfide in an organic amide-based polar solvent has already been reported by Tokko Sho.
No. 45-3368. Poly-p-phenylene sulfide obtained by this method has an extremely low degree of polymerization and a low melt viscosity, and cannot be extruded into fibers, films, etc. Various polymerization methods have been disclosed to obtain poly-p-phenylene sulfide with a high degree of polymerization. For example, in the method disclosed in Japanese Patent Publication No. 52-12240, an alkali metal carboxylate is added to the reaction system as a polymerization aid. This polymerization aid has no effect when added in small amounts, and requires an amount of approximately the same molar amount as sodium sulfide. However, since lithium acetate is expensive, poly-p-phenylene sulfide is effective for increasing the degree of polymerization. The production cost is high and it is not industrially viable. Also, in JP-A-55-40738, alkaline earth metal salts of fatty acids, JP-A-55-40738
No. 43139 discloses aromatic sulfonic acid alkali salts. A high degree of polymerization can be achieved with a relatively small amount of these agents, but their mechanism of action is that a considerable amount of these polymerization aids dissolve in the amide solvent at high temperatures.
A type of salting-out effect that separates poly-p-phenylene sulfide oligomers that have reached a chain length from the solvent system, thereby accelerating the polymerization reaction, while also reducing the decomposition reaction of the polymer that occurs in the solvent. states that it is being suppressed. In addition, in JP-A-56-20030, tri-alkali phosphate was added, in JP-A-56-20031, alkyl phosphate di-alkali salt was added, and in JP-A-57-20031, alkali phosphate di-alkali salt was added.
16028 discloses an alkali metal fluoride. Although many attempts have been made to obtain poly-p-phenylene sulfide with a high degree of polymerization, no satisfactory catalyst system has yet been proposed. In view of this point, the inventors of the present invention have conducted intensive studies on a method for obtaining poly-p-phenylene sulfide with a high degree of polymerization.
We have discovered a completely new catalyst system. That is, p-dihalogenbenzene or p-dihalogenbenzene and at least 3
A poly-p-
This is a method for producing phenylene sulfide. By carrying out the reaction in the presence of a zinc compound, poly-p-phenylene sulfide with a sufficiently high degree of polymerization can be obtained, and at the same time, surprisingly, the coloring of the reaction system can be suppressed, making it possible to suppress the coloration of the reaction system, which is different from conventional catalyst systems. It has been found that a nearly white polymer can be obtained, which could not be obtained by using this method. The main monomer used in the present invention is p-dihalogenbenzene, preferably p-dichlorobenzene; The compounds may also be copolymerized in small amounts.
Such polyhalogen aromatic compounds include 1,
Examples include 2,3-trichlorobenzene, 1,2,4-trichlorobenzene, 2,4,6-trichlorotoluene, and the like. The appropriate amount of the polyhalogen aromatic compound to be added is within 1 mol% of p-dichlorobenzene; if it is more than that, the solvent viscosity of the resulting polymer will become too high, making it difficult to mold, but it will also affect the physical properties of the molded product. No improvement. In addition to the above monomers, aromatic compounds other than p-dichlorobenzene having two halogen substituents in one molecule can also be copolymerized. Such aromatic compounds include m-dichlorobenzene, 2,5
-dichloro-p-xylene, 4,4'-dichlorodiphenyl sulfone, 4,4'-dichlordiphenyl ether, 4,4'-dichlorodiphenyl ketone,
Examples include 1,5-dichloronaphthalene. As the alkali sulfide, hydrates and/or aqueous solutions of sodium sulfide, potassium sulfide, etc. are usually used. In some cases, it is also possible to generate alkali sulfide on the spot by mixing an aqueous alkali bisulfide solution and an aqueous alkali hydroxide solution. Further, a small amount of alkali hydroxide may be added in order to react with a small amount of alkali bisulfide and alkali thiosulfate present in the alkali sulfide. The molar ratio of p-dihalogenbenzene to alkali sulfide is preferably in the range of about 0.95:1 to about 1.2:1. Typical zinc compounds used as polymerization aids include zinc salts of fatty acids such as zinc acetate and zinc stearate, zinc sulfide, zinc oxide, zinc sulfate, zinc phosphate, zinc carbonate, and zinc dithiocarbamate. Examples include salt, zinc oxide, etc. Among these, zinc acetate, zinc sulfide, and zinc phosphate exhibited excellent effects. These zinc compounds may be anhydrous salts or hydrated salts. The amount of zinc compound used can be selected arbitrarily, but
The molar ratio to the alkali sulfide is preferably in the range of 0.01 to 1.5, more preferably in the range of 0.05 to 0.5. That is, although the role of zinc compounds in the production of poly-p-phenylene sulfide is not well understood, due to the coexistence of zinc compounds in the high-temperature reaction system, some of them dissolve and the polymerization reaction It is thought that the degree of polymerization of the polymer is improved by accelerating the reaction or suppressing the decomposition reaction of the polymer that occurs in the solvent. Furthermore, since the zinc compound suppresses the thermal decomposition of the organic amide solvent used as the polymerization solvent, the solvent is less likely to be colored, and an improvement in the recovery rate can be expected. Examples of organic amide solvents include N-methylpyrrolidone, hexamethylphosphoric triamide, tetramethylurea, dimethylformamide, dimethylacetamide, and N-methylpropionamide, with N-methylpyrrolidone being preferred. . The amount of organic amide used as a polymerization solvent, such as N-methylpyrrolidone (hereinafter referred to as NMP), is about 150 to about 1000 per mole of p-dichlorobenzene.
It is preferably within the range of g. Hereinafter, a polymerization recipe will be described in which the solvent is NMP, the alkali sulfide is sodium sulfide, and the zinc compound is zinc acetate. First, predetermined amounts of sodium sulfide, sodium hydroxide, and zinc acetate are added to NMP, and the mixture is gradually heated to about 200°C under a nitrogen stream to continuously distill off water. Then, the reaction vessel is cooled to 160° C. or lower, a monomer such as p-dichlorobenzene and optionally additional NMP are added, the reaction vessel is sealed, and the reaction vessel is pressurized to 1 to 1.5 kg/cm ² with nitrogen. Next, the mixture is heated to about 240 to 300°C and stirred for polymerization. The polymerization time is about 1 hour to about 8 hours. This polymerization reaction is an exothermic reaction, and the internal temperature may rise rapidly in the early stages of polymerization, but in such cases, forced cooling is used to prevent the reaction from running out of control. Rather, it is preferable to gradually raise the temperature at the initial stage of the reaction to prevent a sudden rise in the internal temperature. After the polymerization reaction is completed, the container is cooled, the contents are taken out, thoroughly washed with water, dilute hydrochloric acid, or hot water to remove NMP and inorganic salts, and then dried to isolate the polymer. The polymer p-phenylene sulfide thus obtained has a high degree of polymerization and a melt viscosity sufficient to be melt-molded into fibers, films, plastics, etc. Therefore, the excellent properties that poly-p-phenylene sulfide inherently possesses, such as chemical resistance,
It is extremely useful for molded products that take advantage of its flame retardancy, heat resistance, etc. Note that the melt viscosity of the polymer was measured using a Koka type flow tester (manufactured by Shimadzu Corporation). The standard measurement conditions are 1mm hole diameter, 10mm depth, and a load of 5.
Kg/ ^cm2 . The temperature range was 280°C to 315°C. The present invention will be specifically explained with reference to the following examples, but they are not intended to limit the present invention. Example 1 In a 500 ml autoclave equipped with a stirrer and a temperature sensor, 120.0 g (0.50 mol) of sodium sulfide nonahydrate, 6.0 g (0.15 mol) of sodium hydroxide, and 10.9 g (0.05 mol, sodium sulfide) of zinc acetate dihydrate were added. molar ratio of 0.1) and 200 ml of NMP,
The mixture was gradually heated to 210° C. over about 8.5 hours while passing nitrogen through it, and about 80 ml of water was distilled off. 150 reaction vessels
Cool to ℃ and add 74.3 g of p-dichlorobenzene.
(0.505 mol), 1,2,4-trichlorobenzene
A mixture of 0.27 g (0.3 mol% of p-dichlorobenzene) and 20 ml of NMP was added, sealed under a nitrogen gas pressure of 1.5 Kg/cm ² and heated to an internal temperature of 250°C over about 30 minutes. After maintaining the temperature, the mixture was further heated to raise the internal temperature to 265°C over about 1 hour, and the reaction was continued at this temperature for an additional 3 hours. The pressure at the end of polymerization was 6.5 Kg/cm ² . After cooling the reaction vessel,
The contents were taken out and washed several times with hot water, then with dilute hydrochloric acid, and twice with acetone, and then heated at 120℃ for 16 hours.
Dry under reduced pressure for an hour. The yield of polyphenylene sulfide produced was 45 g. The color of the polymer was grayish white. The melt viscosity of the polymer was 950 poise at 285°C. Comparative Example 1 Example 1 was carried out without adding zinc acetate. The obtained polymer was a dark gray powder.
The melt viscosity was low, 10 poise at 285°C. Example 2 Example 1 was repeated without using sodium hydroxide. The melt viscosity of the obtained polymer was 847 poise at 285°C. Examples 2 to 7, Comparative Examples 2 and 3 Example 1 by changing the type and amount of polymerization aid
The same operation was repeated. The results are summarized in Table 1.

【table】

[Table]

Claims (1)

[Claims] 1. In an organic amide solvent, p-dihalogenbenzene or a mixture of p-dihalogenbenzene and a polyhalogen aromatic compound having at least three halogen substituents is added to an alkali sulfide in the presence of a zinc compound. A method for producing poly-p-phenylene sulfide, which comprises reacting with. 2. The method according to claim 1, wherein the zinc compound is zinc sulfide, zinc phosphate, zinc carbonate, or zinc organic carboxylate.