JPH08134216A - Production of polyarylene sulfide that yields little sulfur-containing gas - Google Patents

Abstract

PURPOSE: To obtain a polyarylene sulfide which is excellent in heat resistance and crystallinity and yields little sulfur-containing gas during heating and melting by reacting an alkali metal sulfide with two specified polyhalo aromatic compounds in two steps. CONSTITUTION: An alkali metal sulfide (e.g. sodium sulfide) is reacted with a polyhalo aromatic compound comprising 1,4-dihalobenzene or dihalonaphthalene. After completion of this main reaction, 1,3-dihalobenzene is added to effect reaction, thus giving a polyarylene sulfide. The suitable amount of the 1,3-dihalobenzene added in the second step is 0.005-0.1mol per mol of the alkali metal sulfide. Since the polyarylene sulfide thus obtained yields a reduced quantity of sulfur-containing gas during heating and melting, it hardly causes corrosion of a mold during molding and is therefore suitable for the production of injection-molded articles, extruded articles, blow-molded articles, etc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention produces a polyarylene sulfide in which the amount of sulfur-based gas generated during heating and melting is reduced without impairing heat resistance and crystallinity and in which die corrosion during molding is less likely to occur. It is about the method. The obtained polyarylene sulfide is used in various molding processing fields such as injection molding, extrusion molding and blow molding.

[0002]

2. Description of the Related Art Polyarylene sulfide (hereinafter referred to as PAS
Is a thermoplastic polymer having excellent heat resistance and chemical resistance, and is used in various molding processing fields. However, when the PAS is heated to a temperature above its melting point and melted in order to mold the PAS, a number of organic and inorganic gases are generated from the PAS, and these gases generate PAS.
There was a drawback that the mold corroded during the molding process. To remedy these drawbacks,
For example, attempts have been made to reduce various gas components by reducing the oligomer component by thermal crosslinking, washing with a reaction solvent, or the like, or by melt-extruding and pelletizing under reduced pressure, but a sufficient effect can be obtained. It wasn't done. Further, a method of stabilizing a polymer by blocking the PAS end with a dihalosulfone represented by 4,4′-dichlorodiphenylsulfone, a monohaloarylene represented by 4-chlorobiphenyl, or the like (US
P4301274, USP4952671) is also presented, but in the former, the reaction rate of the monomer is too fast and it is difficult to bond it only to the terminal. In the latter, on the contrary, the reaction rate is slow and the crystallization rate is lowered. It was difficult to use.

[0003]

The problem of mold corrosion as described above when molding PAS is serious, and an urgent solution is desired. Among the corrosive gases that cause such problems, the problem to be solved by the present invention is to pay particular attention to a sulfur-based gas and reduce the amount of this gas generated.

[0004]

Means for Solving the Problems As a result of repeated investigations by the present inventors, by blocking the end of PAS with 1,3-dihalobenzene, the conventional PAS was obtained without impairing its heat resistance and crystallinity. In comparison, we succeeded in synthesizing PAS that produces a small amount of sulfur-based gas during heating and melting.

That is, the present invention provides a method for producing a polyarylene sulfide by reacting an alkali metal sulfide (A) with a polyhaloaromatic compound (B) as an essential component, and the sulfide (A) and 1,4 -Reacting dihalobenzene or dihalonaphthalene (b1) (main reaction),
A method for producing a polyarylene sulfide is characterized in that 1,3-dihalobenzene (b2) is added and reacted after the reaction is substantially completed. The method of the present invention provides a method for producing PAS in which the amount of sulfur-based gas generated during heating and melting is reduced without impairing heat resistance and crystallinity.

[0006] Generally, PAS is produced by polymerizing an alkali metal sulfide and a polyhaloaromatic compound in the presence of an organic polar solvent.
368, USP 3919177, USP 441572.
9, U.S. Pat. No. 4,645,826 and the like.

In order to produce PAS with a small amount of sulfur-based gas generated during heating and melting by the method of the present invention,
In such a method, the alkali metal sulfide and 1,4-
It is necessary to add 1,3-dihalobenzene after the polymerization reaction (main reaction) with dihalobenzene or the like is substantially completed.

A method for producing PAS in which 1,3-dihalobenzene is added during the polymerization reaction is disclosed in JP-A-2-103.
No. 232 publication. However, when the examples of the publication are repeated, 1,3-dihalobenzene is added when the reaction rate of 1,4-halobenzene is as low as more than 50%, and this method is also disclosed in the publication. As described, the structural units of 1,3-phenylene sulfide are randomly distributed in the copolymer. Therefore, in such a method, heat resistance which is a characteristic of PPS,
The crystallinity is impaired, the melting point is lowered, the crystallinity and the crystallization rate are lowered, and the effect of reducing the amount of generated sulfur-based gas is small.

On the other hand, in the present invention, 1,3-dihalobenzene is added after the polymerization reaction (main reaction) of the alkali metal sulfide with 1,4-dihalobenzene etc. is substantially completed,
It is a method of producing PAS by reacting and producing a small amount of sulfur-based gas during heating and melting. In the method of the present invention in which 1,3-dihalobenzene is added and reacted at the time when the polymerization reaction is substantially completed, the inventors of the present invention block the polymer terminal whose end is an alkali metal salt, and It is considered that the reaction with PAS, which is a 3-monohalophenyl group, is performed. Therefore, it is considered that a PAS having a smaller amount of sulfur-based gas generated during heating and melting can be obtained without impairing its heat resistance and crystallinity, as compared with the conventional PAS.

The alkali metal sulfides used in the present invention include lithium sulfide, sodium sulfide, potassium sulfide, rubidium sulfide, cesium sulfide and mixtures thereof. Further, as such an alkali metal hydroxide,
Lithium hydroxide, sodium hydroxide, potassium hydroxide,
Includes rubidium hydroxide, cesium hydroxide and mixtures thereof. In addition, since alkali metal hydrosulfides and alkali metal thiosulfides are usually present in trace amounts in alkali metal sulfides, an equivalent amount of alkali metal hydroxide corresponding to the reaction with these may be added in excess. it can. Further, these alkali metal sulfides may be synthesized from the alkali metal hydrosulfide and the alkali metal hydroxide during the reaction.
Such alkali metal hydrosulfides include lithium hydrosulfide, sodium hydrosulfide, potassium hydrosulfide, rubidium hydrosulfide, cesium hydrosulfide and mixtures thereof. Such alkali metal sulfides, alkali metal hydroxides and alkali metal hydrosulfides can be used in the form of hydrates and / or aqueous mixtures or anhydrous forms, and there is no limitation on their shape, and they can be crystals, flakes or solutions. It may be in a solid state or a molten state.

The polyhaloaromatic compound used in the main reaction of the present invention described above is excellent in heat resistance and crystallinity.
It is dihalobenzene or dihalonaphthalene. Specific examples include 1,4-dichlorobenzene, 1,4-dibromobenzene, 1-chloro-4-bromobenzene, diiodobenzene, dichloronaphthalene and dibromonaphthalene. Other polyhaloaromatic compounds can be used as long as the heat resistance and crystallinity of the obtained PAS are not impaired. Specifically, 1,3-dichlorobenzene,
1,2-dichlorobenzene, trichlorobenzene, tetrachlorobenzene, trichloronaphthalene, tribromobenzene, triiodobenzene, dichlorodiphenyl sulfone, dibromodiphenyl sulfone, dichlorobenzophenone, dibromobenzophenone, dichlorodiphenyl ether, dibromodiphenyl ether, dichlorodiphenyl sulfide, dibromodiphenyl Sulfide,
Examples thereof include dichlorobiphenyl, dibromobiphenyl, trichlorobiphenyl, tribromobiphenyl, tribromonaphthalene, modified polyhaloaromatics such as dihaloaniline, dihalobenzoic acid and dihalobenzonitrile, and mixtures thereof. Usually, a dihaloaromatic compound is used in the synthesis of PAS, but the polymer has a branched structure,
In order to increase the viscosity, a small amount of a polyhaloaromatic compound having 3 or more halogen substituents in one molecule can be used in combination with a dihaloaromatic compound. Specifically, an example in which 1,4-dihalobenzene is combined with trihalobenzene or tetrahalobenzene in the synthesis of polyphenylene sulfide (PPS) is preferable. When a high viscosity PAS is required, PAS having an arbitrary viscosity can be obtained without increasing the amount of sulfur-based gas generated by thermal crosslinking in the presence of oxygen, and this is a very effective means. obtain.

The polar organic solvent used in the present invention includes formamide, acetamide, N-methylformamide,
N, N-dimethylformamide, N, N-dimethylacetamide, 2-pyrrolidone, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, ε-caprolactam, N-methyl-ε-caprolactam, hexamethylphosphor Amides, tetramethylurea, N, N-dimethylpropyleneurea, 1,3-dimethyl-2-imidazolidinone acid amidoureas and lactams; sulfolane, dimethylsulfolane, and other sulfones; benzonitrile, and other nitriles; methyl Examples include ketones such as phenyl ketone; polyethylene glycol and the like, and mixtures thereof.

In the method of the present invention, the reaction can be carried out in the presence of a polymerization aid, if desired. Examples of the polymerization aid used include lithium halides such as lithium chloride and lithium bromide; lithium carboxylates such as lithium formate and lithium acetate; lithium compounds such as lithium carbonate and lithium oxide; and sodium chloride and sodium bromide. Sodium halide; sodium carboxylate such as sodium formate, sodium acetate; sodium carbonate,
Examples thereof include sodium compounds such as sodium oxide.
Among the above lithium compounds or sodium compounds, lithium chloride, lithium acetate, lithium carbonate or sodium acetate, sodium carbonate and the like are preferable. In the present invention, the above lithium compound or sodium compound may be used alone or in combination of two or more kinds.

The amount of polar organic solvent used in the present invention is
The molar ratio to the alkali metal sulfide is 10 to 2.0, preferably 8.0 to 3.0. The amount of the polyhaloaromatic compound used in the main reaction in the present invention is 0.50 to 10.
0, preferably 0.80 to 5.0, more preferably 0.
It is in the range of 9 to 1.1.

In the method of the present invention, after the reaction (main reaction) between the alkali metal sulfide (A) and 1,4-dihalobenzene or dihalonaphthalene (b1) is substantially completed, 1,3-dihalobenzene ( b2) is added and reacted.

Examples of 1,3-dihalobenzene used include 1,3-dichlorobenzene, 1,3-dibromobenzene, 1-chloro-3-bromobenzene and the like.

The amount of 1,3-dihalobenzene added after the completion of the main reaction is 0.001 to 0.5, preferably 0.002 to 0.5, in terms of molar ratio to the alkali metal sulfide.
3, more preferably 0.005 to 0.1. According to the present inventors' idea of obtaining PAS having a molecular end blocked with a 3-monohalophenyl group, the object can be achieved with a small amount of 1,3-dihalobenzene added. But P
In order to quickly complete the reaction with the AS-terminated S alkali metal salt, unreacted 1,3-dihalobenzene remains in the system and is recovered, but an excessive amount of 1,3-dihalobenzene is added. It is better to do it.

The 1,3-dihalobenzene is added after the main reaction is substantially complete. Here, the main reaction being substantially completed means that the reaction has proceeded until the reaction rate reaches 95% or higher, preferably 98% or higher. Here, the reaction rate refers to the proportion of the component consumed after the main reaction, based on the smaller number of moles of the alkali metal sulfide used in the main reaction or the number of moles of the polyhaloaromatic compound, When the value exceeds 95%, even if the reaction is continued as it is, the reduction of the remaining raw material hardly occurs, and therefore the reaction can be regarded as being substantially completed. If 1,3-dihalobenzene is added at an earlier stage, that is, before the main reaction is substantially completed, the increase in the molecular weight is hindered, or the amount of the meta structure incorporated into the polymer main chain is increased to increase the crystallinity. It may cause a decrease in the crystallization rate or the crystallization rate.

When a polymerization aid is used in the present invention, the amount of the polymerization aid is 0.01 to 2.0, preferably 0.02 to 1.6 in terms of molar ratio to the alkali metal sulfide. If the amount of the polymerization aid is less than the above range, its effect is small, and if it exceeds the above range, the effect of the polymerization aid is not sufficiently exhibited for the added amount, and rather, the polymerization aid is generated in the polymer. May remain at a high concentration, which is not preferable because it causes complication of the washing process.

In the present invention, the reaction temperature is 80 to 300.
The temperature is in the range of ° C, and the temperature can be changed stepwise or continuously during the reaction. The reaction time is also affected by the reaction temperature, but is in the range of 0.5 to 30 hours, preferably 1 to 15 hours. When the reaction time is shorter than this range, it becomes difficult to obtain a polymer having a sufficient viscosity, and when the reaction time is longer than this range, the productivity is deteriorated. Also, this reaction is preferably carried out under an atmosphere of an inert gas.

The reactor used in the present invention is a tank type,
The reaction may be performed in any of a tubular type and a batch operation, a semi-batch operation, or a flow operation. The PAS obtained by the method of the present invention can be obtained by a usual method, for example, by filtering the reaction mixture after the reaction, followed by washing with water, or by diluting the reaction mixture with water, followed by filtration and washing, and further removing the reaction solvent from the reaction mixture. Distilled off,
The reaction mixture can be separated and purified by a method such as subsequent washing with water and washing with an organic solvent.

A typical example of PAS produced by the method of the present invention is PPS (polyphenylene sulfide). However, the PAS produced by the method of the present invention is not limited to this, and includes all polymers and copolymers thereof that can be produced by the above-mentioned raw materials. Further, these polymers can be used after being thermally crosslinked, if necessary. These PASs have an extremely excellent property that the amount of sulfur-based gas generated during heating and melting is small, and by adjusting the copolymerization component, molecular weight and viscosity, injection molding, compression molding, film・
It can be used for various moldings such as extrusion molded products such as fibers, sheets, pipes and tubes and blow molded products, and for sealing electronic parts such as transistors, capacitors and ICs. If necessary, it is also suitable to add a filler, a pigment, a flame retardant, a stabilizer, a silane coupling agent or another polymer to this polymer. For example, glass fibers or carbon fibers may be added to improve mechanical strength and heat resistance.

[0023]

EXAMPLES The method of the present invention will be specifically described below with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

Here, the amount of sulfur-based gas generated during PAS heating and melting was measured by the following method. First, about 0.100 g of PAS polymer was placed in a vial and weighed precisely. Next, it was immersed in a solder bath at 320 ° C. for 15 minutes in a sealed state, taken out, allowed to cool at room temperature for 15 minutes, and then immersed in a dry ice / methanol mixture at −80 ° C. for 15 minutes. Furthermore, 0.
2 ml of 03% hydrogen peroxide solution was added to absorb the generated sulfur-based gas component, the lid was opened, and further 0.03% hydrogen peroxide solution, 3 × 10 ⁻³ M sodium carbonate, 3 × 10 ⁻³
5 ml each of M sodium hydrogen carbonate was added and filtered to obtain a sample solution. Since the sulfur-based gas component generated at this time is oxidized and is in the form of sulfate ion, it is quantified by ion chromatography measurement, and further converted into SO ₂ weight per 1 g of polymer to generate sulfur-based gas. It was evaluated as the amount.

[Example 1] 4.5 with a stirrer having a bottom valve
Into an autoclave, sodium sulfide 2.9 hydrate 556.
1 g (4.271 mol), N-methylpyrrolidone 1500 g, 48.
Charge 10.7 g (0.128 mol) of 0% aqueous sodium hydroxide solution, and under a nitrogen atmosphere up to 200 ° C. for 150 hours over 150 r.
The temperature was gradually raised while stirring at pm, and a mixture of water and some N-methylpyrrolidone was distilled off. The final distillate was 146.01 g. When the water content and sulfur content in this distillate were measured, the water content was 125.28 g (theoretical distillate amount of 228.51 g),
It contained a sulfur content of 15.3 mmol (0.36% based on the charged sulfur content).

Then, the system was closed, 628.76 g (4.277 mol) of 1,4-dichlorobenzene and 338.6 g of N-methylpyrrolidone were added, and polymerization was carried out at 220 ° C. for 4.5 hours. After that, the temperature is raised to 255 ° C. over 30 minutes, and further 3
The reaction continued for an hour. The reaction rate at this time was 99.0%.

With this system kept at 255 ° C., 1,3-
Dichlorobenzene (6.26 g, 0.0426 mol) and N-methylpyrrolidone (3.4 g) were added, and the reaction was further continued for 1 hour.
After completion of the reaction, after cooling to room temperature, the reaction mixture slurry was diluted with a large amount of warm water according to a conventional method, washed with water and dried to obtain 445.6 g of white powdery polyphenylene sulfide (yield 97.0%). . 315.6 ° C. of the present polymer,
The melt viscosity measured at 200 sec ^-1 is 850 poise,
Melting point Tm = 284.2 ° C., crystallization temperature Tc = 232.1.
C., the amount of sulfur-based gas generation was 15 μg per 1 g of polymer in terms of SO ₂ .

[Example 2] 4.5 with a stirrer having a bottom valve
Into an autoclave, sodium sulfide 2.9 hydrate 556.
1 g (4.271 mol), N-methylpyrrolidone 1500 g, 48.
7.13 g (0.0856 mol) of 0% sodium hydroxide aqueous solution was charged, and it was heated to 200 ° C. under a nitrogen atmosphere for 150 hours over 150 hours.
The temperature was gradually raised while stirring at pm, and a mixture of water and some N-methylpyrrolidone was distilled off. The final distillate was 144.55 g. When the water content and sulfur content in this distillate were measured, the water content was 123.60 g (theoretical distillate amount of 226.65 g),
It contained a sulfur content of 13.6 mmol (0.32% based on the charged sulfur content).

Then, the system was closed, and 624.32 g (4.247 mol) of 1,4-dichlorobenzene, 3.86 g (0.0213 mol) of 1,2,4-trichlorobenzene and 338.7 g of N-methylpyrrolidone were added, and at 220 ° C. Polymerization was carried out for 5.5 hours. After that, the temperature is raised to 260 ° C. over 30 minutes, and further 2
The reaction continued for an hour. The reaction rate at this time is 99.3%,
The consumption rate of 1,2,4-trichlorobenzene was 100% (the remaining 1,2
2,4-trichlorobenzene could not be detected).

While keeping this system at 260 ° C., 1,3-
31.29 g (0.213 mol) of dichlorobenzene and 16.8 g of N-methylpyrrolidone were added, and the reaction was continued for another hour.
After completion of the reaction, after cooling to room temperature, the reaction mixture slurry was diluted with a large amount of warm water according to a conventional method, washed with water and dried to obtain 447.2 g (yield 97.3%) of white powdery polyphenylene sulfide. . The melt viscosity of this polymer is 230
00 poise, Tm = 279.7 ° C., Tc = 218.7
C., the amount of sulfur-based gas generation was 28 μg per 1 g of polymer in terms of SO ₂ .

[Embodiment 3] 4.5 with a stirrer having a bottom valve
In an autoclave, sodium sulfide 2.9 hydrate 278.
1 g (2.136 mol), N-methylpyrrolidone 750 g, 48.
3.50 g (0.0427 mol) of 0% sodium hydroxide aqueous solution and 175.2 g (2.136 mol) of sodium acetate were charged, and the temperature was gradually raised to 200 ° C. under nitrogen atmosphere while stirring at 150 rpm for 2 hours. A mixture of N-methylpyrrolidone was distilled off. The final distillate was 71.3 g. When the water content and sulfur content in this distillate were measured, the water content was 61.25 g (theoretical distillate amount 113.33 g) and the sulfur content was 7.2 mmol.
(0.34% of the charged sulfur content).

The system is then closed, 313.11 g (2.130 mol) of 1,4-dichlorobenzene, 1.16 g (0.00639 mol) of 1,2,4-trichlorobenzene and 169.4 g of N-methylpyrrolidone are added and the mixture is heated at 220 ° C. Polymerization was carried out for 5 hours.
After that, the temperature was raised to 260 ° C over 30 minutes, and then 2.5
The reaction continued for an hour. The reaction rate at this time is 99.4%,
The consumption rate of 1,2,4-trichlorobenzene was 100% (the remaining 1,2
2,4-trichlorobenzene could not be detected).

While keeping this system at 260 ° C., 1,3-
Dichlorobenzene 9.39 g (0.0639 mol) and N-methylpyrrolidone 5.1 g were added, and the reaction was continued for another 1.5 hours. After completion of the reaction, after cooling to room temperature, the reaction mixture slurry was diluted with a large amount of warm water according to a conventional method, washed with water and dried to give white granular polyphenylene sulfide 226.1.
g (yield 98.3%) was obtained. The melt viscosity of this polymer is 1
60,000 poise, Tm = 281.7 ° C, Tc = 22
At 4.0 ° C, the amount of sulfur-based gas generation is polymer 1 calculated as SO _2.
It was 24 μg per gram.

COMPARATIVE EXAMPLE 1 Example 1 was repeated except that the reaction was continued for 1 hour without adding 1,3-dichlorobenzene after heating and stirring at 255 ° C. for 3 hours.
The same operation was performed.

By this operation, 444.8 g (yield 96.8%) of white powdery polyphenylene sulfide was obtained. The melt viscosity of this polymer is 870 poise, Tm = 283.3 ° C.,
Tc = 233.1 ° C., and the amount of sulfur-based gas generation was 143 μg per 1 g of polymer in terms of SO ₂ .

[Comparative Example 2] 1,3-Dichlorobenzene was not added after completion of the main reaction but 1,4-dichlorobenzene,
The same operation as in Example 2 was performed except that 1,2,4-trichlorobenzene was added at the same time.

By this operation, 446.1 g (yield 97.0%) of white powdery polyphenylene sulfide was obtained. The melt viscosity of this polymer is 9200 poise, Tm = 258.8.
C., Tc = 162.4 ° C., and the amount of sulfur-based gas generation was 108 μg per 1 g of polymer in terms of SO ₂ .

[Comparative Example 3] 1,3-dichlorobenzene was added after adding 1,4-dichlorobenzene and 1,2,4-trichlorobenzene and reacting at 220 ° C for 1.5 hours. Other than that, the same operation as in Example 2 was performed. Here, when 1,3-dichlorobenzene is added, the reaction rate of 1,4-dichlorobenzene is 72.3%,
Consumption rate of 1,2,4-trichlorobenzene is 99.9%
Met.

By this operation, 446.3 g (yield 97.0%) of white powdery polyphenylene sulfide was obtained. The melt viscosity of this polymer is 13000 poise, Tm = 272.8.
C., Tc = 185.9 ° C., and the amount of sulfur-based gas generation was 82 μg per 1 g of polymer in terms of SO ₂ .

[Comparative Example 4] 4.5 with a stirrer having a bottom valve
Into an autoclave, sodium sulfide 2.9 hydrate 545.
0 g (4.186 mol), N-methylpyrrolidone 1470 g, 48.
Charge 10.5 g (0.125 mol) of 0% sodium hydroxide aqueous solution, and in a nitrogen atmosphere up to 200 ° C. for 150 hours over 150 r.
The temperature was gradually raised while stirring at pm, and a mixture of water and some N-methylpyrrolidone was distilled off. The final distillate was 143.09g. When the water content and the sulfur content in the main distillate were measured, the water content was 122.77 g (theoretical distillate amount 223.94 g),
It contained 15.0 mmol of sulfur (0.36% based on the charged sulfur).

Next, this system was closed, 616.18 g (4.191 mol) of 1,4-dichlorobenzene and 332.9 g of N-methylpyrrolidone were added, and polymerization was carried out at 220 ° C. for 5 hours. Thereafter, the temperature was raised to 260 ° C. over 30 minutes, the reaction was continued for further 2.5 hours, and then cooled. The reaction rate at this time is 9
It was 9.1%. This reaction mixture is referred to as slurry 1.

In a 4.5 l autoclave with a stirrer having a bottom valve, 556.1 g (4.271 mol) of sodium sulfide 2.9 hydrate, 1500 g of N-methylpyrrolidone, 10.7 g (0.128 mol) of 48.0% sodium hydroxide aqueous solution. ) Was charged and the temperature was gradually raised to 200 ° C. under nitrogen atmosphere with stirring at 150 rpm for 2 hours to distill a mixture of water and some N-methylpyrrolidone. The final distillate is 145.32g
Met. The water content and the sulfur content in the main distillate were measured and found to be 126.37 g (theoretical distillate amount of 228.51 g) and 15.8 g for the sulfur content.
It contained mmol (0.37% based on the charged sulfur content).

Next, this system was sealed, and 62.43 g (4.234 mol) of 1,3-dichlorobenzene and 335.2 g of N-methylpyrrolidone were added, and polymerization was carried out at 220 ° C. for 5 hours. Thereafter, the temperature was raised to 260 ° C. over 30 minutes, the reaction was continued for further 2.5 hours, and then cooled. The reaction rate at this time is 9
It was 8.6%. This reaction mixture is referred to as slurry 2.

The whole amount of the slurry 1 obtained in the above reaction and 57.59 g of the slurry 2 were mixed, charged into a 4.5 l autoclave with a stirrer having a bottom valve, purged with nitrogen and then heated to 260 ° C. The reaction was carried out for 3 hours.

After completion of the reaction, after cooling to room temperature, the reaction mixture slurry was diluted with a large amount of warm water according to a conventional method, washed with water, washed and dried to give a white powdery (poly 1,4-phenylene sulfide) / ( 445.9 g (yield 97.0%) of a block copolymer of poly (1,3-phenylene sulfide) was obtained. The melt viscosity of this polymer is 520 poise, Tm = 28
1.7 ° C., Tc = 224.0 ° C., sulfur-based gas generation amount is S
It was 113 μg per 1 g of polymer in terms of O ₂ .

Comparative Example 5 PAS was produced according to the method disclosed in JP-A-2-103232.

A 4.5-liter autoclave with a stirrer equipped with two dropping devices, a reflux condenser and a water-organic substance separator capable of heating, 459.84 g (3.128 mol) of 1,4-dichlorobenzene and N-methylcaprolactam. 2430 g was charged, and the temperature was gradually raised to 215 ° C. under nitrogen atmosphere for 3 hours with stirring at 300 rpm. Sodium sulfide 2.
9-hydrate 931.19 g (7.152 mol), water 253 g, N-methylcaprolactam 113 g, 48% sodium hydroxide 7.2 g (0.3
75 mol) and 489.20 g (3.328 mol) of 1,4-dichlorobenzene were added to N-methylcaprolactam 270
The solution dissolved in g was dropped simultaneously from each of two dropping devices over 2 hours. When the dropping was started, water and a liquid containing 1,4-dichlorobenzene as main components were distilled out, and the latent heat thereof lowered the system temperature to 198 ° C. The liquid distilled out was separated into water and 1,4-dichlorobenzene, and 1,4-dichlorobenzene was returned to the system. After the dropping was completed, a part of the reaction mixture in the system was sampled and the residual 1,4-dichlorobenzene and the sulfidizing agent were analyzed to find the reaction rate, which was 53%.
Here, 31.54 g (0.215 mol) of 1,3-dichlorobenzene
Was added to continue the reaction. During this period, the temperature of the system gradually increased and reached 230 ° C. after 3 hours. Then, the mixture was heated and stirred at this temperature for 8 hours to allow the reaction to proceed.

After completion of the reaction, after cooling to room temperature, the reaction mixture slurry was diluted with a large amount of warm water according to a conventional method, washed with water, washed and dried to give 679.4 g of white powdery polyphenylene sulfide (yield 94.3%). Got

The melt viscosity of this polymer is 440 poise, T
m = 269.2 ° C., Tc = 188.9 ° C., and the amount of sulfur-based gas generation was 56 μg per 1 g of polymer in terms of SO ₂ . [Comparative Example 6] 980.70 g of 1,4-dichlorobenzene (6.6
71 mol) was used and 1,3-dichlorobenzene was not used, and the same operation as in Comparative Example 5 was performed.

By this operation, 682.1 g (yield 94.7%) of white powdery polyphenylene sulfide was obtained. The melt viscosity of this polymer is 510 poise, Tm = 283.8 ° C.,
Tc = 241.0 ° C., and the amount of sulfur-based gas generation was 73 μg per 1 g of polymer in terms of SO ₂ .

[0051]

The PAS according to the present invention is the conventional PAS.
In comparison with, the heat generation resistance and crystallinity are not impaired, the amount of sulfur-based gas generated at the time of heating and melting is reduced, and it has the excellent characteristics that corrosion of the mold during molding is unlikely to occur. Further, according to the present invention, the polyarylene sulfide having various melt viscosities can be produced by using the polyhalobenzene having a functionality of 3 or more in combination without increasing the amount of sulfur-based gas generated by thermal crosslinking. Such PAS can be a very useful material in various molding processing fields such as injection molding, extrusion molding and blow molding.

Claims (3)

[Claims] 1. A method for producing a polyarylene sulfide by reacting an alkali metal sulfide (A) with a polyhaloaromatic compound (B) as an essential component, wherein the sulfide (A) and 1,4-dihalobenzene or A method for producing a polyarylene sulfide, which comprises reacting dihalonaphthalene (b1) (main reaction) and, after the reaction is substantially completed, adding and reacting 1,3-dihalobenzene (b2). 2. After the reaction rate reaches 95% or more, the compound (b2) is added to the sulfide (A) in a molar ratio of 0.005.
2. The production method according to claim 1, wherein the reaction is continued by adding 0.1 to 0.1. 3. The production method according to claim 1, wherein the compound (b1) is 1,4-dihalobenzene alone or a mixture of 1,4-dihalobenzene and trihalobenzene or tetrahalobenzene.