JPH0645692B2 - Method for producing polyarylene sulfide - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing polyarylene sulfide, and more specifically, to a polyarylene sulfide such as polyphenylene sulfide having a high molecular weight and high quality efficiently and stably. Can be manufactured to
Dehydration of the polymerization raw material, which is carried out prior to the polycondensation reaction, can be carried out at a low temperature in a short time, and the generation of impurities due to the decomposition of the polymerization raw material can be effectively suppressed. The present invention relates to a method for producing arylene sulfide.

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

And, polyarylene sulfide such as polyphenylene sulfide is generally known to be obtained by polycondensation reaction of a dihalogenated aromatic compound and an alkali metal sulfide in an organic polar solvent, for example, polyphenylene sulfide The production is usually carried out by polycondensation reaction of p-dichlorobenzene and sodium sulfide in an organic polar solvent.
12240 (corresponding U.S. Pat. Nos. 416,776 and 495,45)
No. 0]).

In order to obtain polyarylene sulfide such as polyphenylene sulfide having excellent properties, it is necessary to increase the molecular weight, and as a method for increasing the molecular weight, a method of controlling the water content of the reaction liquid used in the polymerization reaction has been proposed. ing.

However, since alkali metal sulfides are usually obtained in the form of hydrates, two steps, a dehydration step and a polycondensation step for hydrous alkali metal sulfides, were required in the production of polyarylene sulfide.

This dehydration step has usually been carried out by a method of azeotropically distilling water in the presence of an organic polar solvent, but conventional methods (for example, JP-A-59-98133 and JP-A-61-7332). Bulletin,
JP-A-63-39926, U.S. Pat.No. 4,368,321,
In U.S. Pat. No. 4,317,71, etc.), this dehydration is carried out at normal pressure using an ordinary distillation column or rectification column. Therefore, high temperature heating is necessary to sufficiently dehydrate the polymerization raw material. Distillation under normal pressure while heating to high temperature will cause decomposition of the solvent and alkali metal sulfides, making it impossible to obtain high-quality polymers. Also, 150
Although the above decomposition does not easily occur when heated at a low temperature of about ℃,
There is a problem that the dehydration time becomes long and the efficiency is remarkably lowered.

[Problems to be Solved by the Invention] The present invention has been made based on the above circumstances.

An object of the present invention is to solve the above-mentioned problems, to dehydrate a polymerization raw material which is carried out prior to a polycondensation reaction, at a low temperature and in a short time, and to effectively suppress generation of impurities due to decomposition during dehydration. And to provide a method for producing an improved polyarylene sulfide capable of efficiently and stably producing a high-molecular-weight and high-quality polyarylene sulfide such as polyphenylene sulfide.

[Means for Solving the Problems] As a result of intensive studies to solve the above problems, the present inventors have shown that prior to the polycondensation reaction, instead of the dehydration operation of the polymerization raw material that was conventionally performed under normal pressure. The present invention has been achieved by finding that the above object can be achieved by dehydrating a specific mixture containing a polymerization raw material under reduced pressure in a rectification column.

That is, the present invention for achieving the above-mentioned object is to produce a polyarylene sulfide by contacting a dihalogenated aromatic compound with an alkali metal sulfide and / or an alkali metal hydrosulfide in an organic polar solvent, A method for producing polyarylene sulfide, which comprises dehydrating a mixture of an organic polar solvent and a hydrous alkali metal sulfide and / or a hydrous alkali metal hydrosulfide under reduced pressure in a rectification column.

The organic polar solvent in the method of the present invention [in the following,
It may be referred to as component (D). ], For example, an aprotic organic solvent such as an amide compound, a lactam compound, a urea compound, a cyclic organic phosphorus compound and the like can be mentioned, and particularly, an amide compound and a lactam compound can be mentioned as a preferable example.

Examples of the amide compound include N, N-dimethylformamide, N, N-dimethylacetamide, N, N-diethylacetamide, N, N-dipropylacetamide,
N, N-dimethyl benzoic acid amide etc. can be mentioned.

Examples of the lactam compound include caprolactam, N-methylcaprolactam, N-ethylcaprolactam, N-isopropylcaprolactam, N-isobutylcaprolactam, N-normalpropylcaprolactam, N-normalbutylcaprolactam, N-cyclohexylcaprolactam and N-methyl. -2-pyrrolidone,
N-ethyl-2-pyrrolidone, N-isopropyl-2-
Pyrrolidone, N-isobutyl-2-pyrrolidone, N-normalpropyl-2-pyrrolidone, N-normalbutyl-2-pyrrolidone, N-cyclohexyl-2-pyrrolidone, N-methyl-3-methyl-2-pyrrolidone, N- Cyclohexyl-2-pyrrolidone, N-ethyl-3-methyl-2-pyrrolidone, N-methyl-3,4,5-trimethyl-2-pyrrolidone, N-methyl-2-piperidone, N-
Isopropyl-2-piperidone, N-methyl-2-piperidone, N-ethyl-2-piperidone, N-isopropyl-2-piperidone, N-methyl-6-methyl-2-piperidone, N-methyl-3-ethyl- 2-piperidone etc. can be mentioned.

Further, as aprotic organic polar solvent other than the above, for example, tetramethylurea, N, N'-dimethylethyleneurea, N, N'-dimethylpropyleneurea, 1-methyl-1-oxosulfolane, 1-ethyl-1. -Oxosulfolane, 1-phenyl-1-oxosulfolane, 1-
Methyl-1-oxophosphorane, 1-normal propyl-1-oxophosphorane, 1-phenyl-1-oxophosphorane and the like can be mentioned.

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

Among the various organic polar solvents, preferred are N-alkyllactams and N-alkylpyrrolidones,
Particularly preferred is N-methylpyrrolidone.

As the sulfur source of the polyarylene sulfide in the present invention, a hydrous alkali metal sulfide [hereinafter sometimes referred to as a component (B ₁ )]. ] And / or hydrous alkali metal hydrosulfide [hereinafter sometimes referred to as component (B ₂ ). ] Can be used.

Here, when the hydrous alkali metal hydrosulfide is used, it is usually preferable to use a base together.

This base [In the following, it may be referred to as the component (b ₂ ). ], It is possible to convert an alkali metal hydrosulfide into an alkali metal sulfide, or to efficiently neutralize or receive hydrogen halide that can be generated by condensation of an alkali metal hydrosulfide and a dihalogenated aromatic compound. As long as it is an acid acceptor that can be used and does not hinder the object of the present invention, various types of inorganic bases, organic bases, etc. can be used. As the alkali metal hydroxide, it is possible to preferably use.

Specific examples of the alkali metal hydroxide include lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide and cesium hydroxide.

Among these, lithium hydroxide and sodium hydroxide are preferable, and sodium hydroxide is particularly preferable.

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

Further, these alkali metal hydroxides and other bases may be used as an anhydride, or may be used as a hydrate or an aqueous solution, but usually, they should be used as a substantially anhydrous product. Is desirable.

The base such as an alkali metal hydroxide optionally used is usually a maximum of about 1 equivalent per 1 equivalent (1 mol) of the alkali metal hydrosulfide used.

As the water-containing alkali metal sulfide, a commercially available product or a commonly used compound for industrial use can be used. Specifically, for example, the alkali metal sulfide trihydrate, pentahydrate, hexahydrate, etc. , And polyhydrates such as 9-hydrate, hydrates, and aqueous mixtures.

Examples of the alkali metal sulfides include lithium sulfide, sodium sulfide, potassium sulfide, rubidium sulfide, and cesium sulfide.

Among these, sodium sulfide and lithium sulfide are preferable, and sodium sulfide is particularly preferable.

As the hydrous alkali metal hydrosulfide, a commercially available product or a compound which is usually used for industrial use can be used. Specifically, for example, a trihydrate of an alkali metal hydrosulfide, 5
Examples thereof include polyhydrates such as hydrates, hexahydrates, and 9-hydrates, hydrates, and aqueous mixtures.

Examples of the alkali metal hydrosulfide, for example, lithium hydrosulfide (LiHS), sodium hydrosulfide (NaHS), potassium hydrosulfide (KHS), rubidium hydrosulfide (RbHS), calcium hydrosulfide (CaHS) and cesium hydrosulfide ( CuHS) and the like.

Among these, sodium hydrosulfide and lithium hydrosulfide are preferable, and sodium hydrosulfide is particularly preferable.

Among the above various alkali metal sulfides and alkali metal hydrosulfides, lithium sulfide sodium sulfide is preferable, and sodium sulfide is particularly preferable.

Each of these various alkali metal sulfides and alkali metal hydrosulfides may be used as a hydrate of a single compound, or as a hydrate mixture of two or more compounds.

The dihalogenated aromatic compound [hereinafter sometimes referred to as the component (A). ], Known compounds can be used, and specifically, for example, dihalobenzenes such as m-dihalobenzene and p-dihalobenzene; 2,3-dihalotoluene, 2,5-dihalotoluene, 2,6-dihalotoluene, 3 , 4-dihalotoluene, 2,5-dihaloxylene, 1-ethyl-2,5-dihalobenzene, 1,2,4,5-
Alkyl-substituted dihalobenzenes or cycloalkyl-substituted benzenes such as tetramethyl-3,6-dihalobenzene, 1-normalhexyl-2,5-dihalobenzene, 1-cyclohexyl-2,5-dihalobenzene; 1-
Phenyl-2,5-dihalobenzene, 1-benzyl-
2,5-dihalobenzene, 1-p-toluyl-2,5-
Aryl-substituted dihalobenzenes such as dihalobenzenes;
Dihalobiphenyls such as 4,4′-dihalobiphenyl;
Examples thereof include dihalonaphthalenes such as 1,4-dihalonaphthalene, 1,8-dihalonaphthalene, and 2,8-dihalonaphthalene.

The two halogen atoms in these dihalogenated aromatic compounds are respectively fluorine, chlorine, bromine or iodine, which may be the same or different from each other.

Among the above-mentioned component (A), dihalogenbenzenes are preferable, and p-dichlorobenzene is particularly preferable.

In the method of the present invention, first, the organic polar solvent
(D) is mixed with the hydrated alkali metal sulfide (B ₁ ) and / or the hydrated alkali metal hydrosulfide (B ₂ ) or the hydrated alkali metal hydrosulfide (B ₂ ) and the base (b ₂ ). In order to remove water from the obtained water-containing mixed solution, dehydration operation is performed by azeotropic distillation under reduced pressure using a rectification column.

At this time, in addition to the above components, if desired, an alkali metal halide may be further added to prepare a water-containing mixed liquid.

This alkali metal halide [hereinafter sometimes referred to as the component (C). ], There may be mentioned alkali metal fluorides, chlorides, bromides and iodides, and specific examples thereof include lithium fluoride, sodium fluoride,
Examples thereof include potassium fluoride, cesium fluoride, lithium chloride, sodium chloride, potassium chloride, rubidium chloride and cesium chloride.

Of these, lithium chloride is particularly preferably used.

The organic polar solvent (D) in preparing the water-containing mixture,
The mixing ratio of the water-containing alkali metal sulfide (B ₁ ) and / or the water-containing alkali metal hydrosulfide (B ₂ ) is not particularly limited, but in the usual case, this water-containing mixture is decompressed in a rectification column and decompressed. Organic polar solvent in the dehydrated mixture obtained by distillation (D)
The alkali metal sulfide (B ₁ ) and / or the alkali metal hydrosulfide (B ₂ ) are used in a proportion necessary for producing a polyarylene sulfide with respect to the dihalogenated aromatic compound (A), It can be adjusted appropriately.

The production ratio of the dihalogenated aromatic compound (A) and the alkali metal sulfide and / or the alkali metal hydrosulfide for producing the polyarylene sulfide will be described later, but the dehydrated mixture and the dihalogenated aromatic compound (A ) And so that it only has to be mixed in a predetermined ratio,
Usually, the mixing ratio of the organic polar solvent (D) and the hydrous alkali metal sulfide (B ₁ ) and / or the hydrous alkali metal hydrosulfide (B ₂ ) is 0.1 to 15 times by weight, preferably 2 to 5 times.
It may be mixed in a range of double weight.

Further, in preparing the water-containing mixture, the organic polar solvent (D) and the water-containing alkali metal sulfide (B ₁ ) and / or the water-containing alkali metal hydrosulfide (B ₂ ) or water-containing alkali metal hydrosulfide ( B ₂ ) and the base (b ₂ ) together with 120 to
It is preferable to mix while heating to 160 ° C, especially 130 to 150 ° C.

If the heating temperature is lower than 120 ° C., it may take time for dehydration or insufficient dehydration may occur, and if the heating temperature is higher than 160 ° C., The decomposition rate of the organic polar solvent (D) may increase, which may cause inconvenience such as an increase in the amount of impurities generated.

In the method of the present invention, it is preferable to adjust the top pressure of the rectification column to 200 Torr or less, preferably 150 Torr or less in the vacuum distillation of the water-containing mixture. If the column top pressure exceeds 200 Torr, it is necessary to raise the heating temperature to 160 ° C. or higher, which causes the above-mentioned inconvenience.

Further, the reflux ratio in the rectification column is not particularly limited and may be any reflux ratio as long as it is within the capability range of the rectification column.

The dehydration time cannot be unconditionally determined because it depends on the degree of decompression in the rectification column, but it is usually 0.5 to 5
The time is preferably 0.5 to 3 hours.

The dehydrated mixture thus obtained is mixed with the dihalogenated aromatic compound (A) to be used for the production of polyarylene sulfide.

In the production of polyarylene sulfide, generally,
The dihalogenated aromatic compound as the component (A) is
_The amount of the alkali metal sulfide as the component ( ₁ ) and the alkali metal hydrosulfide as the component (B ₂ ) is usually 0.
It is used in the range of 75 to 2.0 mol, preferably 0.90 to 1.2 mol. This dihalogenated aromatic compound (A) and alkali metal sulfide (B ₁ ) and / or alkali metal hydrosulfide (B ₂ )
Since the reaction with is an equimolar reaction, it is usually within the above range. The amount of the organic polar solvent used as the component (D) is not particularly limited as long as it is an amount sufficient for the reaction to proceed uniformly, but usually the component (A) used, (B
₁₎ component, (B ₂₎ component for further total weight of the multi-component which is optionally used, in the range of 0.1 to 10 times by weight. If the amount used is less than 0.1 times the weight, the reaction may not proceed sufficiently. On the other hand, if it exceeds 10 times the weight, the volumetric efficiency will deteriorate and the productivity will decrease.

Therefore, in the present invention, the dehydrated mixture and the dihalogenated aromatic compound (A) are mixed so that the respective components necessary for polycondensation fall within the ranges described above.

The temperature for the polycondensation reaction is usually in the range of 180 to 330 ° C, preferably 220 to 300 ° C. This reaction temperature is 1
If it is lower than 80 ° C, the reaction rate becomes slow, so that it is not practical. On the other hand, if it exceeds 330 ° C, a side reaction or deterioration of the produced polymer occurs, which causes coloring or gelation.

The reaction time cannot be uniformly determined because it varies depending on the type and amount ratio of each component used, the type and amount of catalyst, the reaction time, etc., but is generally within 20 hours, preferably 0.1
It is about 6 hours.

In the method of the present invention, this polycondensation reaction can be carried out in an atmosphere of an inert gas such as nitrogen, argon or carbon dioxide.

The reaction pressure is not particularly limited, but it is usually from the self pressure of the polycondensation reaction system such as a catalyst to 50 kg / cm ² (absolute pressure). The polycondensation reaction may be a one-step reaction carried out at a constant temperature, a multi-step reaction in which the temperature is raised stepwise, or a reaction mode in which the temperature is gradually and continuously raised.

After the completion of the polycondensation reaction, the synthesized polyarylene sulfide is directly separated from the reaction vessel by a standard method such as filtration or centrifugation, or, for example, water and / or a diluted acid is used. After the flocculation liquid is added, the reaction liquid can be separated and isolated.

Then, the isolated polymer is usually washed with water, methanol, acetone, benzene, toluene, etc. to give an alkali metal halide, an alkali metal sulfide, a catalyst, a polymerization agent attached to the polymer. Auxiliary agents and side reaction products are removed. Alternatively, the polymer produced from the reaction-terminated liquid can be obtained by distilling the solvent off and collecting the polymer without isolating it, and washing the residue as described above. The recovered solvent can be reused.

Further, the used catalyst can be recovered from the separated reaction liquid (mother liquor) and / or the washing liquid after use, purified appropriately, and then repeatedly used in the polymerization reaction.

As described above, a white, highly pure, and sufficiently high molecular weight polyarylene sulfide such as polyphenylene sulfide can be easily and stably obtained in a high yield.

The polyarylene sulfide thus obtained is
Although it can be processed into various molding materials and used, various desalting treatments may be performed as necessary to further reduce the salt content such as sodium chloride in the polymer.

When the polyarylene sulfide obtained by the method of the present invention is molded into various products, for example, other polymers, pigments, graphite, metal powder, glass powder, quartz powder,
It is also possible to mix it with a filler such as glass fiber, a stabilizer, a release agent and the like for molding.

The polyarylene sulfide obtained by the method of the present invention is suitably used in the fields of electric / electronic fields and general molded articles.

EFFECTS OF THE INVENTION According to the present invention, in carrying out a polycondensation reaction by bringing a dihalogenated aromatic compound into contact with an alkali metal sulfide and / or an alkali metal hydrosulfide in an organic polar solvent, an organic polar solvent and Since the water-containing alkali metal sulfide and / or the water-containing mixture of the water-containing alkali metal hydrosulfide is dehydrated under reduced pressure in the rectification column, the amount of impurities generated during the dehydration operation can be suppressed. Using the dehydrated mixture containing a small amount of impurities obtained by this dehydration operation, the polyhalogenation reaction is carried out by bringing the dihalogenated aromatic compound into contact with the alkali metal sulfide and / or the alkali metal hydrosulfide in an organic polar solvent. Since it is carried out, a method for producing an advantageous polyarylene sulfide capable of efficiently and stably obtaining a polyarylene sulfide such as polyphenylene sulfide having excellent properties such as sufficiently high molecular weight and high whiteness is provided. Can be provided.

EXAMPLES Next, examples and comparative examples of the present invention will be shown to more specifically describe the present invention.

(Example 1, Comparative Example 1) The amounts and types of alkali metal sulfides and alkali metal halides shown in Table 1 and the organic polar solvents of the types and amounts shown in Table 1 were set in Table 1 in a mixing tank. The mixture was mixed while heating to the temperature shown in.

The obtained water-containing mixture was rectified in a rectification column having a column top temperature and a column top pressure shown in Table 1 at a reflux ratio shown in Table 1 for a predetermined time.

The dehydrated mixture obtained after the rectification has the water content shown in Table 1, and the decomposition amount of the alkali metal sulfide by the rectification is shown in Table 1.

The dehydrated mixture in the amount shown in Table 1 and a solution of p-dichlorobenzene in the amount shown in Table 1 in N-methylpyrrolidone in the amount shown in Table 1 were charged into a 2SUS316L autoclave, and The polycondensation reaction was carried out at the temperature shown in the table for the time shown in Table 1.

After completion of the reaction, the temperature inside the autoclave was lowered to room temperature, and then the obtained reaction mixture was washed with water and acetone according to a conventional method.

The solid obtained is heated to 100 ° C under high vacuum conditions and
It dried over time and the white polyphenylene sulfide was obtained.

Yield and temperature of the obtained polyphenylene sulfide 20
Table 1 shows the solution viscosity η _inh of polyphenylene sulfide measured using a 1-chloronaphthalene solvent having a concentration of 0.4 g / dl under the condition of 6 ° C.

(Evaluation) As is clear from Table 1, when polyarylene sulfide was produced using a dehydrated mixture obtained by vacuum distillation in a rectification column according to the method of the present invention, impurities in the polycondensation reaction product solution were It is understood that it was possible to produce a high molecular weight polyphenylene sulfide having a small amount and thus a high degree of whiteness.

Claims (1)

[Claims] 1. In producing a polyarylene sulfide by bringing a dihalogenated aromatic compound into contact with an alkali metal sulfide and / or an alkali metal hydrosulfide in an organic polar solvent, the organic polar solvent and the hydrous alkali metal sulfide are used. And / or a hydrous mixture of hydrous alkali metal hydrosulfides are dehydrated under reduced pressure in a rectification column.