JPH0747639B2 - Method for producing polyarylene sulfide - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a polyarylene sulfide, and more specifically, to a high yield of a polyarylene sulfide having a low residual salt content and a high molecular weight. It relates to a method for producing a polyarylene sulfide that can be produced.

[Problems to be Solved by Prior Art and Invention] Polyarylene sulfide such as polyphenylene sulfide is a thermoplastic resin having thermosetting property in a part of its molecule, and has excellent chemical resistance and a wide temperature range. It has excellent properties as an engineering plastic, such as good mechanical properties and heat resistance.

Conventionally, a technique for producing a polyarylene sulfide such as polyphenylene sulfide from an alkali metal sulfide and a polyhalogenated aromatic compound is known (see US Pat. No. 3,354,129, see Japanese Patent Publication No. 45-3368). ). However, in the above-mentioned production method, since the decomposition reaction of the alkali metal sulfide occurs when removing the hydration water of the alkali metal sulfide, the yield of polyarylene sulfide is lowered, and the problems such as the loss of the solvent are caused. There is a point.

As an improved method for solving such a problem, there is a method using an alkali metal hydrosulfide which is easy to dehydrate.

That is, U.S. Pat.
Disclosed is a method of adding ˜1.5 times the molar amount. However, referring to the examples in this specification, the molecular weight is small and the maximum intrinsic viscosity [ηinh] is 0.04 and the melting point is 2
Only polyarylene sulfide with a temperature below 60 ° C was obtained. In addition, in U.S. Pat. No. 3,889,433, alkaline earth metal hydroxides and alkali metal carbonates are used in combination, however, referring to the examples, the intrinsic viscosity [ηinh] is 0.06 or less and the melting point is 263 ° C. Only low molecular weight polyarylene sulfides as shown below are obtained, and such polyarylene sulfides are not suitable as industrial materials.

As an improvement of the production method, Japanese Patent Publication No. 57-14698 discloses a method of using an alkali metal hydrosulfide and an alkali metal hydroxide under specific conditions. However, referring to the examples, only polyarylene sulfides having a low viscosity of about 80 to 83 poise are obtained, and such polyarylene sulfides are not suitable for applications such as fibers for films.

Further, although not explicitly disclosed in this patent publication, since the product obtained as a result of the polymerization is subjected to usual post-treatment, US Pat. No. 4,025,496 and US Pat. No. 4,373, As described in No. 091, the resulting polyarylene sulfide has an ash content of 500 to 6,000 ppm.
It is presumed that some remain.

U.S. Pat.No. 4,025,496 discloses a method for producing a polyarylene sulfide that can be easily separated by defining the order of addition of alkali metal hydroxides. The amount of ash in the polyarylene sulfide is 5,600 ppm. As described above, polyarylene sulfide having a high ash content is not suitable for molding materials, films, filaments and the like, particularly for electronic parts. Furthermore, in this method, since the aqueous solution of the alkali hydroxide is added after the dehydration of the alkali metal hydrosulfide, the dehydration operation has two steps, and therefore the dehydration operation becomes complicated, and the alkali metal hydrosulfide is also added. Is remarkably decomposed and further improvement is desired.

As a method of removing the residual salt from the produced polyarylene sulfide, U.S. Pat. A method of recovering
However, in this method, since the alkali metal salt and the generated polyarylene sulfide are brought into contact with each other while heating after the completion of the polymerization reaction, the purification operation is complicated.

As an improvement on the above-mentioned purification method, US Patent Application No.
The specification of 86,111,458 discloses a method of using an alkali metal halide instead of an alkali metal salt.

On the other hand, US Pat. No. 4,038,263 discloses the use of lithium halides as catalysts in the reaction of alkali metal sulfides with p-dichlorobenzene. According to this method, a high molecular weight polyarylene sulfide can be produced, but the yield of the produced polymer is 70%.
It was a low value of about 85%. It was desired to further improve the yield.

The present invention has been made based on the above circumstances.

That is, an object of the present invention is to solve the above problems and to provide a novel production method capable of producing a high molecular weight polyarylene sulfide having a low salt content and a high yield.

[Means for Solving the Problems] The invention according to claim 1 for achieving the above-mentioned object is a dihalogenated aromatic compound, a halogenated aromatic nitro compound, and an alkali metal hydrosulfide in an organic polar solvent. The method according to claim 2, wherein the polyarylene sulfide is polymerized in the presence of lithium halide. The invention according to claim 2 provides a dihalogenated aromatic compound, a halogenated aromatic nitro compound, an alkali metal hydrosulfide, and 4. A method for producing a polyarylene sulfide, which comprises polymerizing an alkali metal carbonate and an alkali metal hydrosulfide in an organic polar solvent in the presence of a lithium halide. The invention relates to an organic polar solvent, an alkali metal hydroxide and / or an alkali metal carbonate, an alkali metal hydrosulfide and lithium. Dehydrating the mixture of chloride,
A method for producing a polyarylene sulfide, characterized in that a polymerization reaction is carried out by bringing the obtained dehydrated product, a dihalogenated aromatic compound and a halogenated aromatic nitro compound into contact with each other. Dehydrating a mixture of a solvent and an alkali metal hydroxide and / or an alkali metal carbonate, an alkali metal hydrosulfide and a lithium halide,
A method for producing a polyarylene sulfide, characterized in that a polymerization reaction is carried out by bringing the obtained dehydrated product, a dihalogenated aromatic compound, a halogenated aromatic nitro compound, and newly added lithium halide into contact with each other. The invention described in 1) dehydrates a mixture of an organic polar solvent, an alkali metal hydroxide and / or an alkali metal carbonate, an alkali metal hydrosulfide, a lithium halide, a dihalogen aromatic compound and a halogen aromatic nitro compound, and then A method for producing a polyarylene sulfide, which comprises carrying out a polymerization reaction, and the invention according to claim 6 is the polyarylene sulfide according to any one of claims 1 to 5, wherein the lithium halide is lithium chloride. Is a manufacturing method.

The present invention will be further described below.

Examples of the dihalogenated aromatic compound that can be used in the method of the present invention include o-dichlorobenzene, m-dichlorobenzene, p-dichlorobenzene and o-dichlorobenzene.
-Dibromobenzene, p-dibromobenzene, m-dibromobenzene, p-diiodobenzene, 1-chloro-4
-Bromobenzene, dihalogen-substituted benzene such as 1-chloro-4-iodobenzene; 2,5-dichlorotoluene,
2,5-dichloro-p-xylene, 1-ethyl-2,5-dichlorobenzene, 1-ethyl-2,5-dibromobenzene,
1-ethyl-2-bromo-5-chlorobenzene, 1,2,4,
5-tetramethyl-3,6-dichlorobenzene, 1-cyclohexyl-2,5-dichlorobenzene, 1-phenyl-2,5
-Dichlorobenzene, 1-benzyl-2,5-dichlorobenzene, 1-phenyl-2,5-dibromobenzene, 1-
Dihalogen-substituted benzenes such as p-toluyl-2,5-dichlorobenzene, 1-p-toluyl-2,5-dibromobenzene and 1-hexyl-2,5-dichlorobenzene; 4,4 '
Dihalogen-substituted biphenyl such as dichlorobiphenyl; dihalogen biphenylalkanes such as 2,2-di (parachlorophenyl) propane; 1,4-dichloronaphthalene
Examples thereof include dihalogen-substituted naphthalene such as 1,6-dichloronaphthalene and 2,6-dichloronaphthalene.

Among these, preferred are p-dihalogen aromatic compounds, and further p-dihalogenbenzene,
Particularly, p-dichlorobenzene is preferable.

The halogen aromatic nitro compound can be represented by the following general formulas (1), (2) and (3).

(However, X ¹ is a halogen atom, a is 1 or 2, b is 1
Is an integer of 5 and a + b is larger than 3 and smaller than 6. ) [However, Y ¹ is a single bond, —O—, —S—, —SO—, —
(CH ₂ ) _u − (where u is an integer of 1 or more), o and p are each an integer of 0 to 2, and satisfy the relationship of o + p = 1 or 2. Then c
And d are integers of 0 to 5, and 1 <c + d ≦ 10 +
Satisfies the relationship of (o + p). ] (However, e is an integer of 1 or 2, f is an integer of 1 to 4, and e + f is larger than 3 and smaller than 5.) As the compound represented by the general formula (1), for example, Examples include 2,4-dinitrochlorobenzene and 2,5-dichloronitrobenzene.

Examples of the compound represented by the general formula (2) include 2-nitro-4,4'-dichlorodiphenyl ether,
3,3'-dinitro-4,4'-dichlorodiphenyl sulfone and the like can be mentioned.

Examples of the compound represented by the general formula (3) include 2,5-dichloro-3-nitropyridine and 2-chloro-3,5-dinitropyridine.

These mono or dihalogenated aromatic nitro compounds are
They may be used alone or in combination of two or more.

In the present invention, in addition to the compound represented by the above general formula, an alkyl derivative of the compound represented by the above general formula can be used as a mono- or dihalogenated aromatic nitro compound.

Among the various mono- or dihalogenated aromatic nitro compounds, 2,5-dichloronitrobenzene is particularly preferable.

Examples of the alkali metal hydrosulfides include lithium hydrosulfide, sodium hydrosulfide potassium hydrosulfide, rubidium hydrosulfide, and cesium hydrosulfide. Suitable alkali metal hydrosulfides are lithium hydrosulfide and sodium hydrosulfide, and sodium hydrosulfide is particularly preferred. In addition, these may be used individually by 1 type and may be used in combination of 2 or more type.

In the method of the present invention, the alkali metal hydrosulfide can be an anhydride, a hydrate, or an aqueous mixture, but when a hydrate or an aqueous mixture is used, As described below, it is desirable to perform dehydration operation before the reaction. Therefore, it is preferable to use anhydrous alkali metal hydrosulfide because no dehydration operation is required.

Examples of the alkali metal hydroxide used in the present invention include magnesium hydroxide, calcium hydroxide, strontium hydroxide, barium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide and cesium hydroxide. You can

These alkali metal hydroxides may be used alone or in combination of two or more.

Furthermore, the product containing an alkali metal hydroxide, which is obtained by reacting an oxide of an alkali metal with water, can be used as it is.

Preferred in the present invention is sodium hydroxide.

Examples of the alkali metal carbonate used in the present invention include magnesium carbonate, calcium carbonate, strontium carbonate, barium carbonate, sodium carbonate, potassium carbonate, rubidium carbonate and cesium carbonate.

These alkali metal carbonates may be used alone or in combination of two or more.

Preferred in the present invention is sodium carbonate.

As the lithium halide used in the method of the present invention, for example, lithium fluoride, lithium chloride, lithium bromide and lithium iodide are preferable, and lithium chloride is particularly preferable. These lithium halides may be used alone or in combination of two or more.

In the method of the present invention, the lithium halide is
Anhydrate, hydrate or an aqueous mixture can be used, but when a hydrate or an aqueous mixture is used, it is necessary to carry out a dehydration operation before the reaction as described later. There are cases.

Examples of the polar solvent that can be used in the method of the present invention include amide compounds, lactam compounds, urea compounds,
There are cyclic organic phosphorus compounds and the like.

Of these, specific examples of suitable solvents include:
For example, N, N-dimethylformamide, N, N-dimethylacetamide, N, N-diethylacetamide, N, N-dipropylacetamide, N, N-dimethylbenzoic acid amide,
Caprolactam, N-methylcaprolactam, N-ethylcaprolactam, N-isopropylcaprolactam,
N-isobutylcaprolactam, N-propylcaprolactam, N-butylcaprolactam, N-cyclohexylcaprolactam, N-methyl-2-pyrrolidone, N-
Ethyl-2-pyrrolidone, N-isopropyl-2-pyrrolidone, N-isobutyl-2-pyrrolidone, N-propyl-2-pyrrolidone, N-butyl-2-pyrrolidone, N
-Cyclohexyl-2-pyrrolidone, N-methyl-3-
Methyl-2-pyrrolidone, N-cyclohexyl-2-pyrrolidone, N-methyl-3-methyl-2-pyrrolidone,
N-methyl-3,4,5, -trimethyl-2-pyrrolidone, N
-Methyl-2-piperidone, N-ethyl-2-piperidone, N-isopropyl-2-piperidone, N-methyl-
6-methyl-2-piperidone, N-methyl-3-ethyl-2piperidone, N-methyl-2-oxo-hexamethyleneimine, N-ethyl-2-oxo-hexamethyleneimine, hexamethylphosphoric triamide, hexa Ethyl phosphoric acid triamide, tetramethylurea, 1,3-dimethylethylene urea, 1,3-dimethylpropylene urea, 1-methyl-1-oxosulfolane, 1-ethyl-1-oxosulfolane, 1-phenyl-1-oxo Sulfolane, 1
-Methyl-1-oxophosphane, 1-propyl-1-
Examples include oxophosphane and 1-phenyl-1-oxophosphane.

These solvents may be used alone or in combination of two or more.

Further, among the above-mentioned various polar solvents, N-alkyllactam, N-alkylpyrrolidone and hexaalkylphosphoric acid triamide are preferable, and N-methylpyrrolidone is particularly preferable.

In the method of the present invention, a dihalogenated aromatic compound, a halogenated aromatic nitro compound and an alkali metal hydrosulfide in an organic polar solvent in the presence of a lithium halide,
If they can be polymerized, the dihalogen aromatic compound, the halogen aromatic nitro compound, and the alkali metal hydrosulfide can be added to the organic polar solvent in any order or even if they are contacted in the organic polar solvent. The polyarylene sulfide can be produced by polymerizing and, and preferred embodiments are as follows.

First, a dihalogenated aromatic compound, a halogenated aromatic nitro compound, an alkali metal hydroxide and / or an alkali metal carbonate and an alkali metal hydrosulfide are polymerized in an organic polar solvent in the presence of a lithium halide. (Claim 2).

In this case, a mixture of an organic polar solvent, an alkali metal hydroxide and / or an alkali metal carbonate, an alkali metal hydrosulfide and a lithium halide is dehydrated to obtain a dehydrated product, a dihalogen aromatic compound and a halogen aromatic nitro compound. It is preferable to carry out the polymerization reaction by contacting with (Claim 3).

In the dehydration, a part of lithium halide is used, and a part of the lithium halide, an organic polar solvent, an alkali metal hydroxide and / or a mixture of alkali metal carbonate and alkali metal hydrosulfide is dehydrated. Alternatively, the polymerization reaction may be carried out by bringing the obtained dehydrated product, the remaining lithium halide, the dihalogen aromatic compound and the halogen aromatic nitro compound into contact with each other (claim 4).

In some cases, a mixture of an organic polar solvent, an alkali metal hydroxide and / or an alkali metal carbonate, an alkali metal hydrosulfide, a lithium halide, a dihalogen aromatic compound and a halogen aromatic nitro compound is dehydrated, and then a polymerization reaction is performed. It may be performed (Claim 5).

Further, lithium chloride may be used in these polymerization reactions (claim 6).

Dehydration can be performed by azeotropic distillation. Dehydration is preferably carried out in an inert gas such as a nitrogen stream under the conditions usually used, but depending on the case, it may be carried out under reduced pressure or under pressure.

In the dehydration, the compounding ratio (molar ratio) of the lithium halide (A) and the hydrous alkali metal hydrosulfide (B) is usually preferably set as follows.

That is, the molar ratio of component (A) / component (B) is 0.3-
2.0, preferably 0.5 to 1.8. If this molar ratio is less than 0.3, it may not be possible to achieve the desired polyarylene sulfide with a high molecular weight, and it may not be possible to reduce the salt content remaining in the polymer.
On the other hand, if the above molar ratio exceeds 2.0, precipitation of the polymer may occur early during the polymerization, which may make the polymerization operation difficult, and it may not be possible to achieve a high molecular weight polyarylene sulfide.

The mixing ratio (molar ratio) of the alkali metal hydroxide (C) and the alkali metal hydrosulfide (B) during dehydration is
Generally, the following is desirable.

That is, the molar ratio of component (C) / component (B) is 0.8-
It is 1.5, preferably 0.8 to 1.3. If this molar ratio is less than 0.3, the decomposition amount of the alkali metal hydrosulfide may be large, and if the molar ratio exceeds 1.5, the effect of adding the alkali metal hydroxide is Rather, deterioration of the organic polar solvent may be severe.

When the alkali metal carbonate is used instead of the alkali metal hydroxide, the compounding ratio (molar ratio) of the alkali metal carbonate (D) and the alkali metal hydrosulfide (B) is It is the same as the compounding ratio (molar ratio) of the metal hydroxide (C) and the alkali metal hydrosulfide (B).

When the alkali metal hydroxide and the alkali metal carbonate are used in combination, the total number of moles of the alkali metal hydroxide and the alkali metal carbonate and the alkali metal hydrosulfide are
And the number of moles of the alkali metal hydroxide (C)
It is preferable to prepare the same as the compounding ratio (molar ratio) of the alkali metal hydrosulfide (B).

In the polymerization reaction, the compounding ratio of each of the above components is usually preferably set as follows.

That is, the molar ratio of the dihalogenated aromatic compound (E) to the alkali metal hydrosulfide (B) [(E) /
(B)] is usually 0.8 to 1.5, preferably
It is 0.9 to 1.3. Since the reaction between the dihalogenated aromatic compound (E) and the alkali metal hydrosulfide (B) is an equimolar reaction, it is usually within the above range, but when the above molar ratio is less than 0.8, it is industrially useful. In addition to not being able to obtain a good polyarylene sulfide,
May produce by-products of thiophenols.

Blending molar ratio of the halogen aromatic nitro compound (F) and the dihalogen aromatic compound (E) [(F) /
(E)] is usually 0.0001 to 0.05, preferably 0.001 to 0.03. If the molar ratio is less than 0.003, it may not be possible to achieve high molecular weight polyarylene sulfide, and if the molar ratio is greater than 0.05, gelation occurs during polymerization to form a polyarylene sulfide. May not be manufactured.

The organic polar solvent may be used in an amount sufficient for the reaction to proceed smoothly. Usually, the organic polar solvent is 18 mol per mol of the alkali metal hydrosulfide (B).
An amount of use of 0 to 1,000 g is sufficient.

The polymerization reaction is usually 180 ~ 330 ℃, preferably 210 ~ 2
It is carried out in the temperature range of 90 ° C. If the reaction temperature is lower than 180 ° C and the rate of the polymerization reaction is not sufficient, while if it is higher than 330 ° C, a side reaction may be induced or the amount of polyarylene sulfide produced may be decreased.

The reaction pressure of the polymerization reaction is not particularly limited, but usually,
The autogenous pressure of the polymerization reaction system such as a solvent is 10 kg / cm ² (absolute pressure).

The polymerization reaction may be carried out in an atmosphere of an inert gas such as nitrogen, carbon dioxide or water vapor.

The reaction time of the polymerization reaction is usually within 20 hours, particularly 0.
Within 1 to 8 hours.

After the completion of the polymerization reaction, the polyarylene sulfide is directly separated from the reaction solution by a standard method such as filtration or centrifugation, or, for example, water and / or
Alternatively, it can be obtained by diluting and adding an acid and then separating from the reaction solution.

The filtration step is generally followed by a water wash to remove any inorganic components that may adhere to the polymer, such as alkali metal sulfides and alkali hydroxides. In addition to or after this washing step, washing or extraction with other washing liquids such as acetone and methanol, which can be performed, is possible. The polymer can also be recovered by distilling off the solvent from the reaction vessel and subsequently washing as described above.

Since the content of salts such as sodium chloride remaining in the polyarylene sulfide recovered in this manner is significantly smaller than that of the polyarylene sulfide produced by the conventional method using an alkali metal sulfide as a sulfur source, the moisture resistance is high. Highly electrically insulating, the polyarylene sulfide can be molded and processed without particular desalting treatment and can be suitably used in the electric and electronic fields. However, if necessary, the polyarylene sulfide can be used in the cleaning step. In addition, or after that, various desalting treatments may be performed to further reduce the salt concentration of salt or the like in the resin before use.

When molding the polyarylene sulfide obtained by the method of the present invention into various products, other polymers, pigments and fillers such as graphite, metal powder, glass powder,
It can be mixed with additives commonly used for quartz powder or glass fibers, or polyarylene sulfides, for example conventional stabilizers or release agents.

The polyarylene sulfide such as polyphenylene sulfide obtained by the method of the present invention is white and has high purity, and in addition to this, it can be produced in a high yield as a high-molecular-weight resin having a small melt flow. Not only can it be used as a matrix resin for molded products and composite agents, but it can also be used as various molded products, films, fibers, etc., making it ideal for use not only in mechanical parts but also in electrical and electronic parts. It is an engineering plastic.

[Example] (Example 1) 42.8 g (0.543) of sodium hydrosulfide (content: 71%, 29%: water)
Mol), 21.7 g (0.543 mol) of sodium hydroxide in the form of pellets, 23.0 g (0.543 mol) of lithium chloride and 297 ml of N-methylpyrrolidone were charged in one autoclave, and the inside of the autoclave was replaced with nitrogen.

Heat the contents of the autoclave under a nitrogen stream to 120 ° C.
After heating for 1 hour, it was dehydrated by subsequent distillation at 150 ° C. for 1 hour, and 105 ml of a mixed solution of N-methylpyrrolidone and water was distilled off.

After cooling the internal temperature of the autoclave to 100 ° C., 79.5 g (0.54 mol) of p-dichlorobenzene and 0.31 g (0.0016 mol) of 2,5-dichloronitrobenzene were dissolved in 100 ml of N-methylpyrrolidone to obtain a solution. , Added to the dehydrated product,
The autoclave was sealed and the temperature was raised to 260 ° C. to carry out a polymerization reaction for 3 hours.

After completion of the reaction, the reaction product was cooled to around room temperature and then opened, and a slurry reaction product was taken out, filtered to separate a granular polymer, and washed with water (1) twice.
It was further washed with acetone and then dried. The obtained polyphenylene sulfide was 54.5 g (yield 93.0%; based on p-dichlorobenzene). The molecular weight of the obtained polyphenylene sulfide was measured at a concentration of 0.4 g / dl at a temperature of 206 ° C using α-chlornaphthalene as a solvent, and the intrinsic viscosity [ηinh] was 0.38. As a result of quantification by an absorption method, it was 81 ppm.

(Example 2) Except that the amount of lithium chloride used was changed to 12.0 g instead of 23.0 g, dehydration was performed in the same manner as in Example 1 above, and 11.02 g of lithium chloride was charged before charging p-dichlorobenzene. Was carried out in the same manner as in Example 1 above.

As a result, 53.9 g (yield 92%) of polyphenylene sulfide was obtained. As a result of measurement in the same manner as in Example 1, the intrinsic viscosity [ηinh] was 0.35 and the sodium ion content was 88 ppm.

(Comparative Example 1) 91.29 g (0.543 mol) of sodium chloride / pentahydrate, 23.2 g (0.543 mol) of lithium chloride and N-methylpyrrolidone 297 m
N was dehydrated in the same manner as in Example 1 except that
145 ml of a mixture of methylpyrrolidone and water was distilled off.

Then, the procedure was carried out in the same manner as in Example 1 except that after cooling to 100 ° C., 79.8 g (0,543 mol) of p-dichlorobenzene was dissolved in 103 ml of N-methylpyrrolidone and reacted.

As a result, 51.0 g (yield 87%) of polyphenylene sulfide was obtained. As a result of measurement in the same manner as in Example 1, the intrinsic viscosity [ηinh] was 0.28 and the sodium ion content was 105 ppm.

Comparative Example 2 The same as Comparative Example 1 except that 79.5 g (0.541 mol) of p-dichlorobenzene and 0.313 g (0.0016 mol) of dichloronitrobenzene were added in place of 79.8 g of p-dichlorobenzene in Comparative Example 1. It was carried out.

As a result, 49.3 g (yield 84%) of polyphenylene sulfide was obtained. As a result of measurement in the same manner as in Example 1, the intrinsic viscosity [ηinh] was 0.32 and the sodium ion content was 220 ppm.

Comparative Example 3 The procedure of Example 1 was repeated except that lithium chloride was not added.

This comparative example corresponds to the example described in JP-B-57-14698.

In this Comparative Example 3, 57.3 g (yield 98%) of polyphenylene sulfide was obtained. As a result of measurement in the same manner as in Example 1, the intrinsic viscosity [ηinh] was 0.22 and the sodium ion content was 3,150. It was ppm.

Comparative Example 4 The procedure of Example 1 was repeated except that 79.8 g (0.543 mol) of p-dichlorobenzene was used without using lithium chloride and p-dichloronitrobenzene.

As a result, 57.3 g (yield 98%) of polyphenylene sulfide was obtained. As a result of measurement in the same manner as in Example 1, the intrinsic viscosity [ηinh] was 0.17 and the sodium ion content was 2,980 ppm. .

(Example 3) In Example 1, p-dichlorobenzene 67.8 (0.
461 mol) and 2,5-dichloronitrobenzene 0.267 g
(0.0014 mol) was used, and the same procedure as in Example 1 was carried out except that sodium hydroxide in pellet form was not used.

As a result, 13.6 g (yield 27%) of polyphenylene sulfide was obtained. As a result of measurement in the same manner as in Example 1, the intrinsic viscosity [ηinh] was 0.06, and the sodium ion content was 800 ppm.

The polyphenylene sulfide obtained in this example was prepared according to U.S. Patent No. 3,869,433 and U.S. Patent No. 3,876,591.
It has a higher molecular weight than any of the examples described in the specification.

(Example 4) In Example 1, p-dichlorobenzene 69.18
(0.471 mol) and 2,5-dichloronitrobenzene 0.27
g (0.0014 mol), sodium carbonate 28.8 g (0.272 mol) instead of pelletized sodium hydroxide 21.7 g
Was carried out in the same manner as in Example 1 except that

As a result, 27.1 g (yield 53%) of polyphenylene sulfide was obtained. As a result of measurement in the same manner as in Example 1, the intrinsic viscosity [ηinh] was 0.09, and the sodium ion content was 1,100 ppm. .

The polyphenylene sulfide obtained in this example is superior to the polyphenylene sulfide described in US Pat. No. 3,869,433.

Example 5 In this example, the amount of sodium hydrosulfide decomposed was examined.

Sodium hydroxide and sodium hydrosulfide in the amounts shown in Table 1
Water was obtained by charging 42.83 g (0.543 mol), 23.2 g (0.543 mol) of lithium chloride and 297 ml of N-methylpyrrolidone into an autoclave and measuring the amount of hydrogen sulfide produced when distilled in the same manner as in Example 1. The amount of sodium sulfide decomposed was investigated, and the results are shown in Table 1.

The amount of hydrogen sulfide produced was quantified by iodometry after trapping the produced gas with alkali.

From the results shown in Table 1, it can be seen that adding sodium hydroxide before dehydration is advantageous for the polymerization reaction even if the amount of sodium hydrosulfide decomposed is small.

[Effect of the Invention] According to the method of the present invention, it is possible to produce a polyarylene sulfide having a high molecular weight and a salt content lower than that of the polyarylene sulfide obtained by the usual post-treatment in a high yield. The polyarylene sulfide obtained by the method of the present invention has a low salt content and high whiteness.

Claims (6)

[Claims] 1. A method for producing a polyarylene sulfide, which comprises polymerizing a dihalogenated aromatic compound, a halogenated aromatic nitro compound and an alkali metal hydrosulfide in an organic polar solvent in the presence of a lithium halide. . 2. A dihalogenated aromatic compound, a halogenated aromatic nitro compound, an alkali metal hydroxide and / or an alkali metal carbonate and an alkali metal hydrosulfide in an organic polar solvent in the presence of lithium halide. A method for producing a polyarylene sulfide, which comprises polymerizing. 3. A dehydration product, a dihalogen aromatic compound and a halogen aromatic compound obtained by dehydrating a mixture of an organic polar solvent, an alkali metal hydroxide and / or an alkali metal carbonate, an alkali metal hydrosulfide and a lithium halide. A method for producing a polyarylene sulfide, which comprises carrying out a polymerization reaction by contacting with a nitro compound. 4. A dehydration product, a dihalogen aromatic compound and a halogen aromatic compound obtained by dehydrating a mixture of an organic polar solvent, an alkali metal hydroxide and / or an alkali metal carbonate, an alkali metal hydrosulfide and a lithium halide. A method for producing a polyarylene sulfide, which comprises carrying out a polymerization reaction by bringing a nitro compound into contact with a newly added lithium halide. 5. A mixture of an organic polar solvent, an alkali metal hydroxide and / or an alkali metal carbonate, an alkali metal hydrosulfide, a lithium halide, a dihalogen aromatic compound and a halogen aromatic nitro compound is dehydrated and then polymerized. A method for producing a polyarylene sulfide, which comprises carrying out a reaction. 6. The method for producing a polyarylene sulfide according to any one of claims 1 to 5, wherein the lithium halide is lithium chloride.