JPH0421696B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing polyarylene sulfide, and more particularly to a method for producing polyarylene sulfide having a high viscosity and which can be melt-molded. A method for producing polyarylene sulfide by reacting a polyhalogenated aromatic compound with an alkali sulfide in an organic amide-based polar solvent was already published in 1973.
-3368. The polyarylene sulfide obtained by this method has an extremely low degree of polymerization, has a low melt viscosity, and can be used as a fiber.
It cannot be extruded into films, etc. Various methods have been disclosed for obtaining polyarylene sulfides with a high degree of polymerization. For example, the special public official court in 1977-
The method disclosed in No. 12240 involves adding an alkali metal carboxylate as a polymerization aid to the above reaction system. This polymerization aid is ineffective in small amounts, and is required in an amount that is approximately the same molar amount as sodium sulfide.However, lithium acetate, which is particularly effective in increasing the degree of polymerization, is expensive, so the production cost of polyarylene sulfide increases. It is expensive and unindustrial. Also, Unexamined Patent Publication 1973-
40738 contains alkaline earth metal salts of fatty acids, JP-A-Sho
No. 55-43139 discloses aromatic sulfonic acid alkali salts. Further, JP-A-56-20030 discloses the addition of tri-alkali phosphate, JP-A-56-20031 discloses alkyl phosphate dialkali salts, and JP-A-57-16,028 discloses alkali metal fluorides. . A high degree of polymerization has been achieved with these products even in relatively small amounts, but in all cases, a high degree of polymerization can be achieved by adding a small amount of a polyhalogen aromatic compound such as trichlorobenzene to dichlorobenzene to introduce a partially branched structure. Obtaining viscous polyarylene sulfide. In addition, when the present inventors tried these disclosed methods, the solvent was colored black or brown, probably due to decomposition or side reactions of the solvent, and the resulting polymer was often colored from gray to skin color. Color it even more intensely. Decomposition of the solvent reduces the recovery rate of the solvent, and coloration of the polymer makes it difficult to color the molded product, resulting in many problems. In view of this point, the present inventors conducted intensive studies on a method for stably producing polyarylene sulfide with a high degree of polymerization, and as a result, discovered a completely new polymerization aid. That is, a method for obtaining a polyarylene sulfide by reacting a polyhalogenated aromatic compound and an alkali sulfide in an organic amide solvent is characterized in that the reaction is carried out in the presence of an alkaline earth metal phosphate. This is a method for producing polyarylene sulfide. By carrying out the reaction in the presence of an alkaline earth metal phosphate, a polyarylene sulfide with a sufficiently high degree of polymerization can be obtained, and at the same time, surprisingly, the coloration of the reaction system is almost suppressed, which is different from the conventional method. It was discovered that a pure white polymer, which cannot be obtained using a catalyst system, can be obtained. The main monomer polyhalogenated aromatic compound used in the present invention has the formula R'X'n (where each X' is a halogen substituent, preferably chlorine, and n is 2 to 6
is an integer of , R' is a polyvalent aromatic residue of valence n which can have an alkyl substituent, and the number of carbon atoms in the aromatic ring is within the range of 6 to 16. ). The p-dihalogenbenzene used in the present invention is represented by the following formula. (In the formula, X is halogen, R is hydrogen and alkyl,
selected from aralkyl, cycloalkyl, and aryl groups. ) Examples of p-dihalogenbenzene include p-dichlorobenzene, p-dibromobenzene, p-diiodobenzene, 1-chloro-4-bromobenzene, 1-chloro-4-iodobenzene, 2,5-
Dichlorotoluene, 2,5-dichloro-p-xylene, 1-ethyl-4-isopropyl-2,5-
Dibromobenzene, 1,2,4,5-tetramethyl-3,6-dichlorobenzene, 1-hexyl-
3-dodecyl-2,5-dichlorobenzene, 1-
Phenyl-2-chloro-5-bromobenzene, 1
-p-tolyl-2,5-dibromobenzene and mixtures thereof may be mentioned. Among these, p-dichlorobenzene is preferred. In addition, in order to increase the viscosity due to the branched structure, 1
A small amount of a polyhalogen aromatic compound having three or more halogen substituents in the molecule may be copolymerized. Such polyhalogen aromatic compounds include 1,2,3-trichlorobenzene, 1,2,4-
Examples include trichlorobenzene and 2,4,6-trichlorotoluene. The appropriate amount of the polyhalogenated aromatic compound to be added is within 1 mol% of the p-dihalogenbenzene; if it exceeds the amount, the melt viscosity of the resulting polymer will become too high and molding will be difficult, but the physical properties of the molded product will also be affected. No improvement. In addition to the above monomers, aromatic compounds other than p-dichlorobenzene having two halogen substituents in one molecule can also be used. Examples of such compounds include m-dichlorobenzene, 4,4'-dichlorodiphenyl sulfone, 4,4'-dichlorodiphenyl ether, and 4,4'-dichlorodiphenyl ketone. 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 polyhalogenated aromatic compound to alkali sulfide is preferably from about 0.9:1 to about 2:1;
More preferably from about 0.95:1 to about 1.2:1. Typical alkaline earth metal phosphates used as polymerization aids include tricalcium phosphate, but these alkaline earth metal phosphates can be either anhydrous or hydrated. good. The amount of phosphate to be used can be arbitrarily selected, 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. In other words, although the role of phosphates in the production of polyarylene sulfide is not well understood, due to the coexistence of alkaline earth metal phosphates in the high-temperature reaction system, some of the phosphates may be absorbed into the solvent. It is thought that the degree of polymerization of the polymer is improved because it dissolves and accelerates the polymerization reaction, or suppresses the decomposition reaction of the polymer that occurs in the solvent. In addition, since this phosphate 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 the organic amide solvent include N-methylpyrrolidone, hexamethylphosphorylamide, 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 200 to about 1 mol per mole of p-dihalogenbenzene.
It is preferably within the range of 1000g. The polymerization recipe will be explained below when the solvent is NMP, the alkali sulfide is sodium sulfide, and the phosphate is calcium phosphate. First, predetermined amounts of sodium sulfide, sodium hydroxide, calcium phosphate, and NMP are added to a reaction vessel, and the mixture is gradually heated to about 200°C under a nitrogen stream to continuously distill off water. In this dehydration step, when a hydrated phosphate is used, so-called two-stage dehydration can be performed, in which the hydrated water of the phosphate is dehydrated, and then sodium sulfide is continuously added for dehydration. After completion of dehydration, 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 2 hours 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 raise the temperature gradually in 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, and the contents are thoroughly washed with dilute hydrochloric acid and water or hot water to remove NMP and inorganic salts.
Isolate the polymer by drying. The poly-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. In addition, polymers manufactured using phosphoric acid, which is an alkaline earth metal, can be obtained as a nearly white powder, and the molded products and coatings made from this powder are nearly white, and by adding any pigment, it is possible to mold the desired color. products or coatings can be easily obtained. Therefore, poly-p-phenylene sulfide is extremely useful for molded products that take advantage of its inherent excellent properties, such as chemical resistance, flame retardance, and heat resistance. Next, the present invention will be explained in more detail with reference to Examples. In the following examples, the melt viscosity of the polymer was measured using a Koka type flow tester (manufactured by Shimadzu Corporation). Standard measurement conditions are mouthpiece hole diameter 10mm, depth 10
mm, and the load is 5Kg/ ^cm2 . Temperatures were measured in the range 280°C to 315°C. In addition, the color difference (ΔE) is measured using a color difference meter (Nippon Denshoku Kogyo Co., Ltd.).
L, a, b of the reflected light of the sample and standard white plate (magnesium oxide) in the UCS display system devised by RSHunter using
The value was calculated using equation (1). ΔE=√( ₁ − ₂ ) ² + ( ₁ − ₂ ) ² + ( ₁ − ₂ ) ²
(1) Here, L is the lightness, a and b are the scales representing the saturation and hue (to be exact, √ ² + ² is the saturation and b/a is the hue), and the subscript 1 is the scale for each sample, 2 represents the value of the standard white plate. It is shown that the smaller ΔE is, the closer to white the color becomes. Example 1 In a 300 ml autoclave equipped with a stirrer and a temperature sensor, 72.1 g (0.3 mol) of sodium sulfide nonahydrate, 3.6 g (0.09 mol) of sodium hydroxide, 9.3 g (0.03 mol) of tricalcium phosphate, and N-methylpyrrolidone were added. Pour 100ml of water and gradually heat it to 210°C over about 4 hours while passing nitrogen through it, and boil the water to about 51°C.
ml was distilled off. The reaction vessel was cooled to 150°C and p-
Dichlorobenzene 44.57g (0.303mol), 1,2,
0.27 g (0.0015 mol) of 4-trichlorobenzene and 20 ml of NMP were added and the mixture was pressurized to 1.5 Kg/cm ² with nitrogen. Next, heat for about 30 minutes to an internal temperature of 250℃, about 1
After maintaining this temperature for an hour, it 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 is
It was 10Kg/ ^cm2 . After cooling the reaction vessel, the contents were taken out and washed several times with hot water, diluted hydrochloric acid, and further washed twice with water and acetone, and then dried under reduced pressure at 120°C for 16 hours. The yield of polyphenylene sulfide produced was 32 g. The color of the polymer was white. The melt viscosity of the polymer was 2500 poise at 280°C. The polymer after melting was also milky white with little coloring.
Further, the coloring of the solvent after the reaction was small and it was clear and pale yellow. Comparative Example 1 Example 1 was repeated except that 11.4 g (0.03 mol) of trisodium phosphate dodecahydrate was used instead of tricalcium phosphate. The color of the solvent after the reaction was intense and almost black.
The produced polymer was colored beige.
The yield was about 30g. The melt viscosity of the polymer is
It was 3800 poise (265℃). Measurement temperature is 280℃
However, the flow was too much to measure, so I lowered the temperature to 265℃. Examples 2 to 4, Comparative Example 2 The same operations as in Example 1 were repeated by changing the type and amount of the polymerization aid. The results are summarized in Table 1.

[Table] Next, it is shown that the obtained polymer has low coloring property and thermochromic property. The color difference between the obtained polymer powder and the powder heat-treated at 250° C. for 2 hours in air was measured. The results are shown in Table 2.

【table】

Claims (1)

[Claims] 1. A method for obtaining a polyarylene sulfide by reacting a polyhalogenated aromatic compound with an alkali sulfide in an organic amide solvent in the presence of an alkaline earth metal phosphate. A method for producing polyarylene sulfide, which comprises carrying out a reaction. 2. The manufacturing method according to claim 1, wherein the polyhalogenated aromatic compound is p-dihalogenbenzene or a mixture of p-dihalogenbenzene and a polyhalogenated aromatic compound having at least three halogen substituents. 3. The manufacturing method according to item 1, wherein the alkaline earth metal phosphate is tricalcium phosphate.