JP2010037550A - Cyclic polyarylene sulfide, and method for recovering polyarylene sulfide - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a high-purity cyclic polyarylene sulfide and a polyarylene sulfide having a small content of a linear polyarylene sulfide oligomer. <P>SOLUTION: An organic polar solvent is distilled out from a mixture containing at least a cyclic polyarylene sulfide, a polyarylene sulfide, and the organic polar solvent; and the obtained mixture is solid-liquid separated in a temperature range in which the polyarylene sulfide becomes insoluble to produce a high-purity cyclic polyarylene sulfide and a polyarylene sulfide having a small content of a linear polyarylene sulfide oligomer. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a cyclic polyarylene sulfide and a method for recovering a polyarylene sulfide, and a high purity ring is obtained by distilling off the organic polar solvent from a mixture containing at least the polyarylene sulfide, the cyclic polyarylene sulfide and the organic polar solvent. The present invention relates to a method for recovering a polyarylene sulfide having a low content of formula polyarylene sulfide and linear polyarylene sulfide oligomer.

  Polyarylene sulfide (hereinafter sometimes abbreviated as PAS) represented by polyphenylene sulfide (hereinafter also abbreviated as PPS) has excellent heat resistance, barrier properties, chemical resistance, electrical insulation properties, and heat and humidity resistance. It is a resin having properties suitable as an engineering plastic such as flame retardancy. Also, it can be molded into various molded parts, films, sheets, fibers, etc. by injection molding and extrusion molding, and widely used in fields requiring heat resistance and chemical resistance such as various electric / electronic parts, mechanical parts, and automotive parts. It has been.

  As a specific method for producing this PAS, a method of reacting an alkali metal sulfide such as sodium sulfide with a polyhaloaromatic compound such as p-dichlorobenzene in an organic amide solvent such as N-methyl-2-pyrrolidone is proposed. This method is widely used as an industrial production method for PAS. In this production method, a linear polyarylene sulfide oligomer which is a PAS component having a low molecular weight is produced in the PAS polymerization stage. However, in the usual polyarylene sulfide recovery method, the linear polyarylene sulfide oligomer is a polyarylene. There is a problem that it is recovered together with sulfide. When these linear polyarylene sulfide oligomers are mixed in the polyarylene sulfide, the mechanical performance such as the bending strength of the product is lowered, the amount of gas generated when the resin is melted is increased, and the mold and die during the molding process are also increased. This may increase dirt. Therefore, a method for separating a linear polyarylene sulfide oligomer from a polyarylene sulfide is desired. Usually, the polyarylene sulfide is separated and removed through a purification process such as washing with an organic solvent (see, for example, Patent Document 2). However, these processes take a long time, resulting in a decrease in productivity and an increase in cost. It becomes a factor.

  In addition to the linear polyarylene sulfide oligomer, it is known that cyclic polyarylene sulfide exists as a PAS component having a low molecular weight (see, for example, Patent Document 3). Aromatic cyclic compounds can be applied to highly functional materials and functional materials based on properties resulting from their cyclic properties, such as properties as inclusion compounds, high molecular weight linear chains by ring-opening polymerization, etc. In recent years, it has attracted attention due to its specificity derived from its structure, such as its use as a useful monomer for the synthesis of molecular compounds. Cyclic polyarylene sulfides also belong to this category and are notable compounds. However, the cyclic polyarylene sulfide has a weight average molecular weight close to that of the linear polyarylene sulfide oligomer, and therefore has similar properties such as solubility in an organic solvent. Therefore, it is difficult to separate the linear polyarylene sulfide oligomer and the cyclic polyarylene sulfide by a normal purification method, and it is extremely difficult to obtain a high-purity cyclic polyarylene sulfide in a high yield.

  Therefore, in order to produce high-purity cyclic polyarylene sulfide and polyarylene sulfide having a low content of linear polyarylene sulfide oligomer, a method for reducing the amount of linear polyarylene sulfide oligomer contained in the system is desired. .

  As a method for reducing the amount of linear polyarylene sulfide oligomer contained in a mixture obtained by reacting a dihalogenated aromatic compound and a sulfidizing agent in an organic polar solvent, a part of the solvent is removed during the reaction. (For example, refer to Patent Document 4), and a method of increasing the molecular weight of the linear polyarylene sulfide oligomer by removing a part of the solvent during the reaction and then adding water to the system ( For example, refer to Patent Document 5.) Further, a part of the solvent is removed during the reaction, and then a polymerization aid is added to the system to increase the molecular weight of the linear polyarylene sulfide oligomer (for example, refer to Patent Document 6). ) Is disclosed. However, since these methods aim to obtain a polyarylene sulfide having a reduced content of linear polyarylene sulfide oligomer, there is no disclosure regarding a method for recovering a cyclic polyarylene sulfide. In addition, in these methods, since the amount of the organic polar solvent when reacting the dihalogenated aromatic compound and the sulfidizing agent is reduced, it can be expected that the amount of cyclic polyarylene sulfide produced is small. It cannot be said that this is an efficient method for recovering arylene sulfide.

Japanese Patent No. 3200027 JP 59-6221 A JP-A-5-163349 Japanese Patent Laid-Open No. 5-230214 JP-A-6-49208 JP 2002-284876 A

  An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a method for recovering polyarylene sulfide having a low content of high-purity cyclic polyarylene sulfide and linear polyarylene sulfide oligomer.

The present invention employs the following means in order to solve such problems.
That is, the present invention
(1) From a mixture (a) comprising at least polyarylene sulfide, cyclic polyarylene sulfide and an organic polar solvent, wherein the cyclic polyarylene sulfide is 6 parts by weight or more with respect to 100 parts by weight of polyarylene sulfide. A method for recovering a cyclic polyarylene sulfide and a polyarylene sulfide, the organic polar solvent being distilled off from the mixture (a), and a mixture (b) comprising at least the polyarylene sulfide, the cyclic polyarylene sulfide and the organic polar solvent And a process for solid-liquid separation (c) of the mixture (b) in a temperature region in which the polyarylene sulfide is insoluble, and a method for recovering the cyclic polyarylene sulfide and the polyarylene sulfide.
(2) As the mixture (a), a mixture containing at least a sulfidizing agent, a dihalogenated aromatic compound and an organic polar solvent is used in an amount of 1.25 liters or more of an organic polar solvent with respect to 1 mol of a sulfur component in the mixture, A cyclic polyarylene sulfide and a method for recovering a polyarylene sulfide according to (1), wherein a mixture obtained by heating and reacting is used. (3) The mixture (a) includes at least a polyarylene sulfide and a sulfide. Using a mixture obtained by reacting a mixture containing an oxidant, a dihalogenated aromatic compound and an organic polar solvent with heating using 1.25 liters or more of the organic polar solvent with respect to 1 mol of the sulfur component in the mixture. (1) cyclic polyarylene sulfide and method for recovering polyarylene sulfide
(4) The amount of the organic polar solvent in the mixture (a) is 1.25 liters or more with respect to 1 mol of the sulfur component in the mixture (a), and any one of (1) to (3) A method for recovering cyclic polyarylene sulfide and polyarylene sulfide according to claim 1.
(5) In the step of distilling off the organic polar solvent from the mixture (a), the organic polar solvent is used until the amount of the remaining organic polar solvent is 1.0 liter or less with respect to 1 mol of the sulfur component in the mixture (b). The cyclic polyarylene sulfide and the polyarylene sulfide recovery method according to any one of (1) to (4), wherein
(6) The method includes a step of obtaining a cyclic polyarylene sulfide mixture as a solid from a filtrate component obtained by performing solid-liquid separation (c) in a temperature range in which polyarylene sulfide is insoluble ( The cyclic polyarylene sulfide and the method for recovering polyarylene sulfide according to any one of 1) to (5).
(7) The amount of the organic polar solvent in the mixture (b) containing at least polyarylene sulfide, cyclic polyarylene sulfide and the organic polar solvent obtained by distilling off the organic polar solvent is in the mixture (b). The cyclic polyarylene sulfide and the method for recovering polyarylene sulfide according to any one of (1) to (6), wherein the amount is 0.10 liter or more per 1 mol of the sulfur component.
(8) The mixture recovered from the filtrate components obtained by solid-liquid separation (c) contains 50% by weight or more of cyclic polyarylene sulfide, (1) to (7) Cyclic polyarylene sulfide and method for recovering polyarylene sulfide.
(9) The method for recovering a cyclic polyarylene sulfide and polyarylene sulfide according to any one of (1) to (8), wherein the temperature at which the organic polar solvent is distilled off is 140 ° C. or higher.
(10) The method for recovering a cyclic polyarylene sulfide and polyarylene sulfide according to any one of (1) to (9), wherein the temperature at which the organic polar solvent is distilled off is 180 ° C. or higher.
(11) The method according to any one of (1) to (10), further including a step of removing the alkali metal halide salt from the mixture containing at least the polyarylene sulfide and the alkali metal halide salt obtained by the solid-liquid separation (c). The cyclic polyarylene sulfide and the method for recovering the polyarylene sulfide.

  According to the present invention, when recovering polyarylene sulfide and cyclic polyarylene sulfide from a mixture containing polyarylene sulfide, cyclic polyarylene sulfide and organic polar solvent, the organic polar solvent is distilled off, By performing the separation, it is possible to recover high-purity cyclic polyarylene sulfide, it is possible to recover polyarylene sulfide having a low content of linear polyarylene sulfide oligomer, and the particle size of polyarylene sulfide can be increased. Therefore, the effect that polyarylene sulfide can be efficiently recovered can be obtained.

  Hereinafter, the present invention will be described in detail.

(1) Cyclic polyarylene sulfide The cyclic polyarylene sulfide in the present invention is a cyclic compound having a repeating unit of the formula:-(Ar-S)-as a main structural unit, and preferably the repeating unit is 80 It is a compound such as the following general formula (a) that contains at least mol%.

Here, examples of Ar include units represented by the following formulas (A) to (S), among which the formulas (A) to (SA) are preferable, and the formulas (A) and (U) are preferred. Is more preferable, and the formula (I) is particularly preferable (wherein R1 and R2 are each a substituent selected from hydrogen, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, and a halogen group). Yes, R1 and R2 may be the same or different.)

  In addition, in cyclic polyarylene sulfide, repeating units, such as said Formula (I)-Formula (S), may be included at random, may be included in a block, and any of those mixtures may be sufficient. Typical examples of these include cyclic polyphenylene sulfide, cyclic polyphenylene sulfide sulfone, cyclic polyphenylene sulfide ketone, cyclic random copolymers containing these, cyclic block copolymers, and mixtures thereof. . Particularly preferred cyclic polyarylene sulfides include p-phenylene sulfide units as the main structural unit.

Is a cyclic polyphenylene sulfide containing 80 mol% or more, particularly 90 mol% or more (hereinafter sometimes abbreviated as cyclic PPS).

  Although there is no restriction | limiting in particular in the repeating number m in the said (a) formula of cyclic polyarylene sulfide, 2-50 are preferable, 2-25 are more preferable, and 3-20 can be illustrated as a still more preferable range.

  The cyclic polyarylene sulfide may be either a single compound having a single repeating number or a mixture of cyclic polyarylene sulfides having different repeating numbers.

(2) Polyarylene sulfide The polyarylene sulfide in the present invention is a linear homopolymer having a repeating unit of the formula:-(Ar-S)-as the main constituent unit, preferably containing 80 mol% or more of the repeating unit. Or a linear copolymer. Ar includes units represented by the above formulas (a) to (su), among which the formula (a) is particularly preferable (provided that R1 and R2 in the formula are hydrogen, from 1 carbon number). 6 is an alkyl group having 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, and a substituent selected from a halogen group, and R1 and R2 may be the same or different.

  As long as this repeating unit is a main structural unit, it can contain a small amount of branching units or crosslinking units represented by the following formulas (C) to (H). The amount of copolymerization of these branched units or cross-linked units is preferably in the range of 0 to 1 mol% with respect to 1 mol of-(Ar-S)-units.

  In addition, the polyarylene sulfide in the present invention may be any of a random copolymer, a block copolymer and a mixture thereof containing the above repeating unit.

  Typical examples of these include polyphenylene sulfide, polyphenylene sulfide sulfone, polyphenylene sulfide ketone, random copolymers thereof, block copolymers, and mixtures thereof. Particularly preferred polyarylene sulfides include p-phenylene sulfide units as the main structural unit of the polymer.

In addition to polyphenylene sulfide (hereinafter sometimes abbreviated as PPS) containing 80 mol% or more, particularly 90 mol% or more, polyphenylene sulfide sulfone and polyphenylene sulfide ketone.

  Although there is no restriction | limiting in particular in the molecular weight of various polyarylene sulfide in this invention, As a weight average molecular weight of general polyarylene sulfide, 2000-1 million can be illustrated, 2500-500000 are preferable and 5000-100000 are more preferable. In general, polyarylene sulfide having a weight average molecular weight within the above range is particularly excellent in properties such as mechanical strength and chemical resistance. Here, the weight average molecular weight is a value calculated in terms of polystyrene by gel permeation chromatography (GPC).

(3) Linear polyarylene sulfide oligomer The linear polyarylene sulfide oligomer in the present invention preferably has a repeating unit of the formula:-(Ar-S)-as the main structural unit, and preferably contains 80 mol% or more of the repeating unit. A linear homopolymer or a linear copolymer. Ar includes units represented by the above formulas (a) to (su), among which the formula (a) is particularly preferable (provided that R1 and R2 in the formula are hydrogen, from 1 carbon number). And a substituent selected from an alkyl group of 6, an alkoxy group having 1 to 6 carbon atoms, and a halogen group, and R1 and R2 may be the same or different.

  As long as this repeating unit is a main constituent unit, a small amount of branch units or crosslinking units represented by the above formulas (C) to (H) can also be included. The amount of copolymerization of these branched units or cross-linked units is preferably in the range of 0 to 1 mol% with respect to 1 mol of-(Ar-S)-units.

  Further, the linear polyarylene sulfide oligomer in the present invention may be any of a random copolymer, a block copolymer and a mixture thereof containing the above repeating unit.

  Typical examples thereof include linear polyarylene sulfide oligomers, linear polyphenylene sulfide sulfone oligomers, linear polyphenylene sulfide ketone oligomers, random copolymers, block copolymers, and mixtures thereof. Particularly preferred linear polyarylene sulfide oligomers include p-phenylene sulfide units as the main structural unit.

Is a linear polyphenylene sulfide oligomer containing 80 mol% or more, particularly 90 mol% or more.

  The average molecular weight of various linear polyarylene sulfide oligomers in the present invention can be defined as lower than the above-mentioned polyarylene sulfide oligomer, and the weight average molecular weight of a general linear polyarylene sulfide oligomer can be exemplified by 200 to 5000, 200 -4000 are preferable and 300-3000 are more preferable. Here, the weight average molecular weight is a value calculated in terms of polystyrene by gel permeation chromatography (GPC).

(4) Sulfiding agent The sulfiding agent used in the present invention is not particularly limited as long as it can introduce a sulfide bond into a dihalogenated aromatic compound. Examples thereof include alkali metal sulfides, alkali metal hydrosulfides, and hydrogen sulfide. It is done.

  Specific examples of the alkali metal sulfide include lithium sulfide, sodium sulfide, potassium sulfide, rubidium sulfide, cesium sulfide, and a mixture of two or more thereof, among which lithium sulfide and / or sodium sulfide are preferable. Sodium sulfide is more preferably used. These alkali metal sulfides can be used as hydrates or aqueous mixtures or in the form of anhydrides. The aqueous mixture refers to an aqueous solution, a mixture of an aqueous solution and a solid component, or a mixture of water and a solid component. Since generally available inexpensive alkali metal sulfides are hydrates or aqueous mixtures, it is preferable to use such forms of alkali metal sulfides.

  Specific examples of the alkali metal hydrosulfide include, for example, lithium hydrosulfide, sodium hydrosulfide, potassium hydrosulfide, rubidium hydrosulfide, cesium hydrosulfide and a mixture of two or more thereof, among them lithium hydrosulfide and Sodium hydrosulfide is preferable, and sodium hydrosulfide is more preferably used.

  Moreover, the alkali metal sulfide prepared in a reaction system from an alkali metal hydrosulfide and an alkali metal hydroxide can also be used. Further, an alkali metal sulfide prepared by previously contacting an alkali metal hydrosulfide and an alkali metal hydroxide can also be used. These alkali metal hydrosulfides and alkali metal hydroxides can be used as hydrates or aqueous mixtures, or in the form of anhydrides. From the viewpoint of availability and cost of hydrates or aqueous mixtures. preferable.

  Furthermore, alkali metal sulfides prepared in the reaction system from alkali metal hydroxides such as lithium hydroxide and sodium hydroxide and hydrogen sulfide can also be used. Further, alkali metal sulfides prepared by previously contacting alkali metal hydroxides such as lithium hydroxide and sodium hydroxide with hydrogen sulfide can also be used. Hydrogen sulfide can be used in any form of gas, liquid, and aqueous solution.

  In the present invention, the amount of the sulfidizing agent is subtracted from the actual charge when the loss of the sulfidizing agent partially occurs before the start of the reaction with the dihalogenated aromatic compound due to dehydration operation or the like. It shall mean the remaining amount.

  An alkali metal hydroxide and / or an alkaline earth metal hydroxide can be used in combination with the sulfidizing agent. Specific examples of the alkali metal hydroxide include, for example, sodium hydroxide, potassium hydroxide, lithium hydroxide, rubidium hydroxide, cesium hydroxide, and a mixture of two or more thereof. Specific examples of the metal hydroxide include, for example, calcium hydroxide, strontium hydroxide, barium hydroxide, and sodium hydroxide is preferably used.

  When an alkali metal hydrosulfide is used as the sulfidizing agent, it is particularly preferable to use an alkali metal hydroxide at the same time, but the amount used is from 0.95 mol to 1 per mol of the alkali metal hydrosulfide. A range of .50 mol, preferably 1.00 mol to 1.25 mol, and more preferably 1.005 to 1.200 mol can be exemplified. When hydrogen sulfide is used as the sulfiding agent, it is particularly preferable to use an alkali metal hydroxide at the same time. The amount of the alkali metal hydroxide used in this case is 2.0 to 3.0 with respect to 1 mole of hydrogen sulfide. The range of mol, Preferably it is 2.01 mol-2.50 mol, More preferably, it is 2.04-2.40 mol.

(5) Dihalogenated aromatic compound Examples of the dihalogenated aromatic compound used in the present invention include p-dichlorobenzene, o-dichlorobenzene, m-dichlorobenzene, p-dibromobenzene, o-dibromobenzene, m-dibromobenzene, Dihalogenated benzene such as 1-bromo-4-chlorobenzene, 1-bromo-3-chlorobenzene, and 1-methoxy-2,5-dichlorobenzene, 1-methyl-2,5-dichlorobenzene, 1,4-dimethyl- Examples thereof include dihalogenated aromatic compounds containing substituents other than halogen such as 2,5-dichlorobenzene, 1,3-dimethyl-2,5-dichlorobenzene, and 3,5-dichlorobenzoic acid. Especially, the dihalogenated aromatic compound which has p-dihalogenated benzene represented by p-dichlorobenzene as a main component is preferable. Particularly preferably, it contains 80 to 100 mol%, more preferably 90 to 100 mol% of p-dichlorobenzene. It is also possible to use two or more different dihalogenated aromatic compounds in combination in order to produce a cyclic polyarylene sulfide copolymer.

(6) Organic Polar Solvent In the production of the cyclic polyarylene sulfide and polyarylene sulfide of the present invention, an organic polar solvent is used as a reaction solvent, and among them, an organic amide solvent is preferably used. Specific examples include N-alkylpyrrolidones such as N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone and N-cyclohexyl-2-pyrrolidone, caprolactams such as N-methyl-ε-caprolactam, An aprotic organic solvent typified by 3-dimethyl-2-imidazolidinone, N, N-dimethylacetamide, N, N-dimethylformamide, hexamethylphosphoric triamide, etc., and a mixture thereof, have a stable reaction. It is preferably used because it is expensive. Among these, N-methyl-2-pyrrolidone and 1,3-dimethyl-2-imidazolidinone are preferable, and N-methyl-2-pyrrolidone is more preferably used.

(7) Alkali metal halide salt The alkali metal halide salt in the present invention is produced by the reaction of a sulfidizing agent and a dihalogenated aromatic compound, produced by reaction of other components in the reaction system, or sulfidized. All alkali metal halide salts present in the mixture are included, such as alkali metal halide salts introduced into the reaction system at an optional stage such as before, during and after the reaction of the agent and the dihalogenated aromatic compound. Alkali metal halide salts include any combination of alkali metals, i.e. lithium, sodium, potassium, rubidium and cesium and halogens, i.e. fluorine, chlorine, bromine, iodine and astatine. Examples include lithium chloride, sodium chloride, potassium chloride, lithium bromide, sodium bromide, potassium bromide, lithium iodide, sodium iodide, potassium iodide, cesium fluoride, and the like. The alkali metal halide salt produced by the reaction of the sulfidizing agent and the dihalogenated aromatic compound is composed of the alkali metal contained in the sulfidizing agent and the halogen contained in the dihalide. Examples of the alkali metal halide salt resulting from the combination of the agent and the dihalogenated aromatic compound include lithium chloride, sodium chloride, potassium chloride, lithium bromide, sodium bromide, potassium bromide and sodium iodide. Sodium chloride, potassium chloride Sodium bromide and potassium bromide can be exemplified as preferable examples, and sodium chloride is more preferable.

(8) Preparation method of mixture (a) In the present invention, cyclic polyarylene is subjected to a step of distilling off the organic polar solvent from the mixture (a) containing at least polyarylene sulfide, cyclic polyarylene sulfide and organic polar solvent. The sulfide and polyarylene sulfide are recovered.

  Here, the mixture (a) is a mixture containing at least polyarylene sulfide, cyclic polyarylene sulfide and an organic polar solvent, and 6 parts by weight or more of cyclic polyarylene sulfide with respect to 100 parts by weight of polyarylene sulfide. Including, preferably 7 parts by weight or more, more preferably 8 parts by weight or more. Further, the upper limit of the amount of the cyclic polyarylene sulfide in the mixture (a) is not limited, but preferably contains 70 parts by weight or less of cyclic polyarylene sulfide with respect to 100 parts by weight of polyarylene sulfide, and contains 45 parts by weight or less. More preferred are those containing 20 parts by weight or less. Furthermore, the amount of the organic polar solvent in the mixture (a) is preferably 1.25 liters or more, more preferably 1.5 liters or more, and further preferably 2 liters with respect to 1 mole of the sulfur component in the mixture (a). It refers to the above. Although there is no restriction | limiting in particular in the upper limit of the quantity of the organic polar solvent in a mixture (a), 50 liters or less are preferable with respect to 1 mol of sulfur components in a mixture (a), 20 liters or less are more preferable, Especially preferably, 15 Less than a liter. Here, the amount of the organic polar solvent is based on the volume of the solvent at normal temperature and pressure.

  As a method for preparing the mixture (a) in the present invention, any method can be used as long as the mixture having the above composition can be prepared, but (I) a mixture containing at least a sulfidizing agent, a dihalogenated aromatic compound and an organic polar solvent, Preferred preparation method is a preparation method by heating and reacting, and (II) a preparation method by heating and reacting a mixture containing at least a polyarylene sulfide, a sulfidizing agent, a dihalogenated aromatic compound and an organic polar solvent. It can be illustrated as Hereinafter, this preferable preparation method will be described in detail.

(9) Preparation method (I) of mixture (a)
A method for preparing a mixture (a) comprising at least a polyarylene sulfide, a cyclic polyarylene sulfide and an organic polar solvent, and a method of reacting by heating at least a mixture comprising a sulfidizing agent, a dihalogenated aromatic compound and an organic polar solvent. Can be exemplified as a preferred preparation method.

  At this time, the amount of the dihalogenated aromatic compound used is preferably in the range of 0.9 to 2.0 mol, more preferably in the range of 0.95 to 1.5 mol, per mol of the sulfur component of the sulfidizing agent. The range of 1.005 to 1.2 mol is more preferable.

  In addition, the reaction temperature at which the sulfidizing agent and dihalogenated aromatic compound are reacted by heating varies uniquely depending on the type and amount of the sulfidizing agent, dihalogenated aromatic compound, and organic polar solvent used in the reaction, and is thus uniquely determined. Although it cannot be performed, a range of usually 120 to 350 ° C, preferably 180 to 320 ° C, more preferably 220 to 310 ° C, and further preferably 225 to 300 ° C can be exemplified. In this preferable temperature range, a higher reaction rate can be obtained, and the reaction tends to be uniform and proceed easily. The reaction may be either a one-step reaction performed at a constant temperature, a multi-stage reaction in which the temperature is raised stepwise, or a reaction in which the temperature is continuously changed.

  The reaction time depends on the type and amount of the raw material used or the reaction temperature, and thus cannot be defined unconditionally, but is preferably 0.1 hour or longer, more preferably 0.5 hour or longer. By setting it as this preferable time or more, since unreacted raw material components can be reduced sufficiently, the produced cyclic polyarylene sulfide and polyarylene sulfide tend to be easily recovered. On the other hand, the reaction time is not particularly limited, but the reaction proceeds sufficiently even within 40 hours, preferably within 10 hours, more preferably within 6 hours.

  The amount of the organic polar solvent used in preparing the mixture (a) by heating and reacting a mixture containing at least the sulfidizing agent, the dihalogenated aromatic compound and the organic polar solvent is 1 mol of the sulfur component in the mixture. On the other hand, it is preferably 1.25 liters or more, more preferably 1.5 liters or more, and further preferably 2 liters or more. The upper limit of the amount used is not particularly limited, but from the viewpoint of efficiently producing cyclic polyarylene sulfide and polyarylene sulfide, the amount is preferably 50 liters or less per mole of sulfur component of the sulfidizing agent, The following is more preferable, and 15 liters or less is still more preferable. Here, the amount of solvent used is based on the volume of the solvent under normal temperature and pressure.

  In preparing the mixture (a) by the above method, there is no particular limitation on the pressure when the sulfidizing agent and the dihalogenated aromatic compound are brought into contact with each other, and the pressure varies depending on the raw materials constituting the mixture, its composition, reaction temperature, and the like. Although it cannot be defined uniquely, the lower limit of the preferable pressure can be exemplified by a gauge pressure of 0.05 MPa or more, more preferably 0.3 MPa or more. In addition, since the pressure increase due to the self-pressure of the mixture occurs at the preferable reaction temperature of the present invention, the lower limit of the preferable pressure at such a reaction temperature is 0.25 MPa or more, more preferably 0.3 MPa or more as a gauge pressure. it can. Moreover, as a preferable upper limit of pressure, 10 MPa or less, More preferably, 5 MPa or less can be illustrated. In such a preferable pressure range, the time required for bringing the sulfidizing agent and the dihalogenated aromatic compound into contact with each other tends to be shortened. In addition, when the amount of the organic polar solvent used when the sulfidizing agent and the dihalogenated aromatic compound are brought into contact with each other is increased, that is, the concentration of the sulfidizing agent and dihalogenated aromatic compound as raw materials in the mixture is low. Under the conditions, the effect of performing the reaction in the preferable pressure range tends to be particularly large, and the raw material consumption rate tends to be further improved. The reason for this is not clear at this time, but some of the raw materials such as dihalogenated aromatic compounds that are volatile under such heating conditions exist in the gas phase in the reaction system, and the reaction with the reaction substrate in the liquid phase part. The reaction may become difficult to proceed, and it is speculated that the reaction proceeds more efficiently because the volatilization of the raw material in the reaction system can be suppressed by setting the pressure within the above preferable range. Further, in order to set the pressure at the time of heating the mixture to the above-mentioned preferable pressure range, the reaction system with an inert gas described later is preferably used at an optional stage such as before starting the reaction or during the reaction, preferably before starting the reaction. It is also a preferable method to pressurize the inside. Here, the gauge pressure is a relative pressure based on the atmospheric pressure, and is equivalent to a pressure difference obtained by subtracting the atmospheric pressure from the absolute pressure.

  In the method of preparing the mixture (a) by bringing the sulfidizing agent and the dihalogenated aromatic compound into contact with each other and reacting in this method, the reaction is carried out as a mixture comprising an organic polar solvent, a dihalogenated aromatic compound and a sulfidizing agent as essential components. I do. In addition to the essential components, a third component that does not significantly inhibit the reaction and a third component that has an effect of accelerating the reaction can be added to the mixture. Although there is no restriction | limiting in particular in the method of performing reaction, It is preferable to carry out on stirring conditions. In addition, there is no restriction | limiting in particular in the temperature at the time of charging a raw material here, For example, you may react after charging a raw material near room temperature, or charge a raw material to the reaction container temperature-controlled beforehand to the temperature preferable for reaction mentioned above. It is also possible to carry out the reaction. It is also possible to continuously carry out the reaction by sequentially charging the raw material into the reaction system in which the reaction is performed.

It is also possible to use a sulfidizing agent, a dihalogenated aromatic compound, and an organic polar solvent containing water. In general, a reaction using a sulfidizing agent and a dihalogenated aromatic compound requires a strict reduction in the amount of water because the reaction rate tends to decrease as the amount of water in the mixture increases. Therefore, it is possible to carry out the reaction sufficiently without strictly controlling the amount of water in the mixture. Therefore, the amount of water in the mixture (a) of the present method is not particularly limited, but the amount of water at the start of the reaction, that is, at the stage where the conversion rate of the dihalogenated aromatic compound charged into the reaction system is 0, An example of a preferable range is 0.2 mol or more and 20 mol or less per mol of sulfur component, preferably 0.5 mol or more and 10 mol or less, and more preferably 0.6 mol or more and 8 mol or less. When the sulfidizing agent, organic polar solvent, dihalogenated aromatic compound, and other components that form the mixture contain water, and the amount of water in the mixture exceeds the above range, On the way, it is possible to reduce the amount of water in the reaction system to make the amount of water within the above range, and thus the reaction tends to proceed efficiently in a short time. Moreover, when the water content of the mixture is less than the above preferable range, it is also a preferable method to add water so that the water content becomes the above. The conversion rate of the dihalogenated aromatic compound is a value calculated by the following formula. The residual amount of the dihalogenated aromatic compound can be usually determined by gas chromatography.
(A) When dihalogenated aromatic compound is added excessively in molar ratio with respect to sulfidizing agent Conversion (%) = [[Feed amount of dihalogenated aromatic compound (mol) -Remaining amount of dihalogenated aromatic compound (Mol)) / [dihalogenated aromatic compound (mol) -excess amount of dihalogenated aromatic compound (mol)]] × 100
(B) In cases other than the above (a) Conversion (%) = [[DHA charge (mol) -DHA remaining amount (mol)] / [DHA charge (mol)]] × 100

  Further, in the preparation of the mixture (a), at any stage where the raw materials charged by continuing the reaction for a desired time are reduced, any one or more of a sulfidizing agent, a dihalogenated aromatic compound and an organic polar solvent are added. It is also possible to continue the reaction. It is important to consider the amount of the sulfur component in the mixture before the addition, and the amount of the organic polar solvent is 1 with respect to 1 mol of the sulfur component in the mixture after the addition of the raw material. It is desirable to add within the range of 25 liters or more.

  As described above, the addition of the sulfidizing agent and the dihalogenated aromatic compound allows an optional stage in which charged raw materials are reduced, but the conversion rate of the dihalogenated aromatic compound is 50% or more. This step is preferable, and a 70% step is more preferable. By adding at such a step, the reaction tends to proceed more efficiently.

  In addition, when the amount of water in the mixture changes due to the addition of the raw material, it is also possible to perform an additional operation to achieve the above-described preferable amount of water, before adding, during the addition, after the addition It is also desirable to remove any amount of water from the mixture. In the removal of water, when components other than water are removed from the mixture, a sulfidizing agent, a dihalogenated aromatic compound, and an organic polar solvent can be further added as necessary. An operation of returning the components back to the mixture may be performed.

  In addition, in the method for preparing the mixture (a) by bringing the sulfidizing agent and the dihalogenated aromatic compound into contact and reacting in this method, various known polymerization methods and reaction methods such as a batch method and a continuous method are employed. be able to. Further, the atmosphere in the production is preferably a non-oxidizing atmosphere, preferably in an inert gas atmosphere such as nitrogen, helium, and argon. From the viewpoint of economy and ease of handling, a nitrogen atmosphere is preferable.

(10) Preparation method (II) of mixture (a)
In the present invention, a mixture containing polyarylene sulfide, a sulfidizing agent, a dihalogenated aromatic compound, and an organic polar solvent is reacted by heating to thereby contain at least polyarylene sulfide, cyclic polyarylene sulfide, and an organic polar solvent. It is also possible to prepare a mixture (a).

  The reaction temperature at which a mixture containing polyarylene sulfide, a sulfidizing agent, a dihalogenated aromatic compound and an organic polar solvent is reacted by heating depends on the type and amount of the mixture, the structure of the polyarylene sulfide used as a raw material, the molecular weight, etc. Although it cannot be uniquely determined because of diversification, a range of usually 120 to 350 ° C, preferably 200 to 320 ° C, more preferably 230 to 300 ° C, and further preferably 240 to 280 ° C can be exemplified. In this preferable temperature range, the polyarylene sulfide used as a raw material melts and dissolves in the mixture. The raw material polyarylene sulfide is generally in a solid state near room temperature, and in the solid state, the formation reaction of the target mixture (a) is difficult to proceed, but the polyarylene sulfide is preferably dissolved as described above. By carrying out the reaction in the temperature range, the reaction system becomes uniform and the reaction rate dramatically improves, and the time required for the reaction tends to be shortened. The reaction may be any of a one-step reaction performed at a constant temperature, a multi-step reaction in which the temperature is raised stepwise, or a type in which the temperature is continuously changed.

  The reaction time depends on the structure and molecular weight of the raw material polyarylene sulfide used, sulfidizing agent, dihalogenated aromatic compound, organic polar solvent, and the amount of these raw materials or the reaction temperature. 0.1 hours or more is preferable, and 0.5 hours or more is more preferable. By setting it as this preferable time or more, since unreacted raw material components can be reduced sufficiently, the produced cyclic polyarylene sulfide and polyarylene sulfide tend to be easily recovered. On the other hand, the reaction time is not particularly limited, but the reaction proceeds sufficiently even within 10 hours, preferably within 6 hours, more preferably within 3 hours.

  The amount of the organic polar solvent used in preparing the mixture (a) by heating and reacting a mixture containing at least the polyarylene sulfide, the sulfidizing agent, the dihalogenated aromatic compound and the organic polar solvent is as follows. The amount is preferably 1.25 liters or more, more preferably 1.5 liters or more, and even more preferably 2 liters or more, with respect to 1 mole of the sulfur component. The upper limit of the amount used is not particularly limited, but from the viewpoint of efficiently producing cyclic polyarylene sulfide and polyarylene sulfide, it is preferably 50 liters or less per mole of sulfur component in the mixture, and 20 liters or less. Is more preferable, and 15 liters or less is still more preferable. Here, the amount of solvent used is based on the volume of the solvent under normal temperature and pressure.

  In the preparation method of the mixture (a) of the present method, there is no particular limitation on the pressure at which the mixture is heated, and since it varies depending on the raw materials constituting the mixture, its composition, reaction temperature, etc., it cannot be uniquely defined. However, the lower limit of the preferable pressure is 0.05 MPa or more, more preferably 0.3 MPa or more, and further preferably 0.4 MPa or more in gauge pressure. In addition, since the pressure rise by the self-pressure of the mixture occurs at the preferable reaction temperature of the present method, the lower limit of the preferable pressure at such a reaction temperature is 0.25 MPa or more, more preferably 0.3 MPa or more as a gauge pressure. it can. Moreover, as a preferable upper limit of pressure, 10 MPa or less, More preferably, 5 MPa or less can be illustrated. In such a preferable pressure range, the time required for preparing the mixture (a) tends to be shortened. Further, in the case where the amount of the organic polar solvent used in the preparation of the mixture (a) is increased, that is, in the condition where the concentration of the polyarylene sulfide, the sulfidizing agent and the dihalogenated aromatic compound as raw materials in the mixture is low, the preferable pressure range. There is a tendency that the effect of carrying out the reaction is particularly great, and the raw material consumption rate tends to be further improved. The reason is presumed as described above. Further, in order to set the pressure at the time of heating the mixture to the preferred pressure range, the reaction system is filled with an inert gas at an optional stage such as before starting the reaction or during the reaction, preferably before starting the reaction. Pressing is also a preferred method. Here, the gauge pressure is a relative pressure based on atmospheric pressure, and is equivalent to a pressure value obtained by subtracting atmospheric pressure from absolute pressure.

  In the preparation method of the mixture (a) according to this method, a polyarylene sulfide, a sulfidizing agent, a dihalogenated aromatic compound, and an organic polar solvent are charged in a reaction vessel, and the reaction is carried out as a mixture containing these as essential components. In addition to the essential components, a third component that does not significantly inhibit the reaction and a third component that has an effect of accelerating the reaction can be added to the mixture. Although there is no restriction | limiting in particular in the method of performing reaction, Performing on stirring conditions is preferable for homogenization of a reaction system. In addition, there is no restriction | limiting in particular in the temperature at the time of charging a raw material here, For example, you may react after charging a raw material near room temperature, or charge a raw material to the reaction container temperature-controlled beforehand to the temperature preferable for reaction mentioned above. It is also possible to carry out the reaction. It is also possible to continuously carry out the reaction by sequentially charging the raw material into the reaction system in which the reaction is performed.

  It is also possible to use a sulfidizing agent, a dihalogenated aromatic compound, polyarylene sulfide, and an organic polar solvent containing water. In general, a reaction using a sulfidizing agent and a dihalogenated aromatic compound requires a strict reduction in the amount of water because the reaction rate tends to decrease as the amount of water in the mixture increases. Therefore, it is possible to carry out the reaction sufficiently without strictly controlling the amount of water in the mixture. Therefore, the amount of water in the mixture (a) of the present method is not particularly limited, but the amount of water at the start of the reaction, that is, at the stage where the conversion rate of the dihalogenated aromatic compound charged into the reaction system is 0, An example of a preferable range is 0.2 mol or more and 20 mol or less per mol of sulfur component, preferably 0.5 mol or more and 10 mol or less, and more preferably 0.6 mol or more and 8 mol or less. When the sulfidizing agent, organic polar solvent, dihalogenated aromatic compound, polyarylene sulfide and other components forming the mixture contain water and the water content in the mixture exceeds the above range, before the reaction is started In the middle of the reaction, an operation of reducing the amount of water in the reaction system can be performed so that the amount of water can be within the above range, whereby the reaction tends to proceed efficiently in a short time. Moreover, when the water content of the mixture is less than the above preferable range, it is also a preferable method to add water so that the water content becomes the above. The conversion rate of the dihalogenated aromatic compound is a value calculated by the above formula.

  Further, in the preparation of the mixture (a), at any stage where the reaction is continued for a desired time and the charged raw materials are reduced, any of polyarylene sulfide, sulfidizing agent, dihalogenated aromatic compound and organic polar solvent, or It is also possible to continue the reaction by adding more. It is important to consider the amount of the sulfur component in the mixture before the addition, and the amount of the organic polar solvent is 1 with respect to 1 mol of the sulfur component in the mixture after the addition of the raw material. It is desirable to add within the range of 25 liters or more.

  As described above, the addition of polyarylene sulfide, sulfidizing agent and dihalogenated aromatic compound is allowed as an optional step in which the charged raw materials are reduced, but the conversion rate of dihalogenated aromatic compound Is preferably 50% or more, more preferably 70%, and the reaction tends to proceed more efficiently by adding at such a stage.

  In addition, when the amount of water in the mixture changes due to the addition of the raw material, it is also possible to perform an additional operation to achieve the above-described preferable amount of water, before adding, during the addition, after the addition It is also desirable to remove any amount of water from the mixture. In the removal of water, when components other than water are removed from the mixture, a sulfidizing agent, a dihalogenated aromatic compound, and an organic polar solvent can be further added as necessary. An operation of returning the components back to the mixture may be performed.

  For the preparation of the mixture (a), various known polymerization methods and reaction methods such as a batch method and a continuous method can be employed. Further, the atmosphere in the production is preferably a non-oxidizing atmosphere, and it is preferably performed in an inert gas atmosphere such as nitrogen, helium, and argon. In particular, from the viewpoint of economy and ease of handling, a nitrogen atmosphere is preferable. preferable. The reaction pressure is not particularly limited because it cannot be defined unconditionally depending on the type and amount of the raw material and solvent used, or the reaction temperature.

(11) Distillation of organic polar solvent In order to produce cyclic polyarylene sulfide and polyarylene sulfide by the method of the present invention, the organic polar solvent is distilled off from the mixture (a) prepared by the method described above. Is essential.

  As a method for distilling off the organic polar solvent, any method is particularly problematic as long as the organic polar solvent can be excluded from the reaction system from the mixture (a) and the amount of the organic polar solvent contained in the mixture (a) can be reduced. However, preferred methods include distillation of an organic polar solvent under reduced pressure or increased pressure, removal of the solvent by filtration, removal of the solvent by flash transfer, and addition of a substance having a strong affinity for the solvent. And a method of substantially removing the solvent out of the reaction system by expressing phase separation in the method, in particular, a method of distilling the organic polar solvent under reduced pressure or under pressure, a method of removing the solvent by flash transfer is more preferable, A method of distilling the organic polar solvent under reduced pressure or increased pressure is more preferable. Further, when distilling the organic polar solvent under reduced pressure or under pressure, an inert gas such as nitrogen, helium, or argon may be used as a carrier gas.

  The temperature at which the organic polar solvent is distilled off varies depending on the type of the organic polar solvent and the composition of the mixture (a), and therefore cannot be uniquely determined, but a preferable range is 140 to 320 ° C. . Especially, 180-320 degreeC is more preferable, 190-310 degreeC is further more preferable, and 200-300 degreeC is especially preferable. In the temperature range of 180 to 320 ° C., most of the polyarylene sulfide is dissolved in the organic polar solvent, and it can be expected that the molecular chain growth reaction of the polyarylene sulfide proceeds during the distillation. Furthermore, since the organic polar solvent is distilled off, the growth terminal concentration in the system is increased, and as a result, the molecular chain growth reaction is considered to proceed at an accelerated rate. Therefore, the high molecular weight reaction of the polyarylene sulfide and linear polyarylene sulfide oligomer contained in the mixture (a) proceeds while the organic polar solvent is distilled off, and is finally contained in the mixture (b). The amount of linear polyarylene sulfide oligomer is reduced. As described above, since the linear polyarylene sulfide oligomer here has a low weight average molecular weight, its physical properties such as solubility in various solvents are close to that of the cyclic polyarylene sulfide, and therefore, separation from the cyclic polyarylene sulfide is difficult. Compound. Therefore, it is preferable that the amount of the linear polyarylene sulfide oligomer remaining in the mixture (b) is small. Although the effect is limited, the temperature at which the organic polar solvent is distilled off may be in the range of 140 to 180 ° C. Even when the organic polar solvent is distilled off in this temperature range, the amount of the linear polyarylene sulfide oligomer contained in the cyclic polyarylene sulfide mixture recovered by the solid-liquid separation (c) tends to be reduced. The details of the effect are not clear at present, but the molecular chain growth reaction of the linear polyarylene sulfide oligomer proceeds even in the temperature range of 140 to 180 ° C., and the separation from the cyclic polyarylene sulfide is achieved by solid-liquid separation (c). It is presumed that the high molecular weight reaction has progressed to the extent possible.

  Further, the distillation may be either one-stage distillation performed at a constant temperature, multi-stage distillation in which the temperature is raised stepwise, or distillation in the form of continuously changing the temperature.

  Since the time required for the distillation depends on the type and amount of the organic polar solvent used or the distillation temperature, it cannot be generally specified, but is preferably 0.1 hours or more, more preferably 0.3 hours or more, and 5 hours or more is more preferable. By setting it as this preferable time or more, high molecular weight of the linear polyarylene sulfide oligomer contained in the mixture (a) tends to proceed easily. Furthermore, after distilling off the organic polar solvent, the molecular weight of the linear polyarylene sulfide oligomer proceeds by continuing the reaction at the same temperature or higher, and the purity of the cyclic polyarylene sulfide tends to increase. Furthermore, since the amount of the linear polyarylene sulfide oligomer contained in the polyarylene sulfide tends to be reduced, it is preferable to use such means.

  When distilling off the organic polar solvent, if the organic polar solvent is distilled off excessively, the polyarylene sulfide tends to precipitate and solidify, and the viscosity of the mixture (b) tends to increase and the operability tends to deteriorate. . Therefore, the amount of the organic polar solvent to be distilled off cannot be uniquely determined because it varies depending on the type of the organic polar solvent, the amount used in the reaction, etc. It is preferable that it becomes 0.10 liter or more with respect to 1 mol of sulfur components in b), it is still more preferable that it will be 0.15 liter or more, and it is more preferable that it will be 0.20 liter or more.

  On the other hand, if the amount of the organic polar solvent distilled off is too small, the effect of the present invention tends to be reduced. Accordingly, the amount of the organic polar solvent to be distilled off cannot be uniquely determined because it varies depending on the type of the organic polar solvent, the amount used in the reaction, etc. The solvent is preferably distilled off to 1.0 liter or less, more preferably 0.8 liter or less, and more preferably 0.5 liter or less to 1 mol of the sulfur component in the mixture (b). More preferably, the solvent is distilled off until

  Furthermore, the present inventors have examined in detail the physical properties of polyarylene sulfide obtained by distilling off the organic polar solvent, and as a result, the median diameter of the polyarylene sulfide powder diameter can be reduced by distilling off the organic polar solvent. It has been found that the median diameter of the resulting polyarylene sulfide powder tends to increase by increasing the particle size distribution of the polyarylene sulfide and increasing the amount of the organic polar solvent to be distilled off. . Therefore, by distilling off the organic polar solvent, the separation efficiency of the solid-liquid separation (c) in the temperature range where the polyarylene sulfide described below becomes insoluble is improved, and the cyclic polyarylene sulfide having higher purity can be recovered. . At this time, the organic polar solvent is distilled off in a temperature range preferable by distilling off the organic polar solvent, that is, a temperature range of 180 to 320 ° C, more preferably 190 to 310 ° C, and particularly preferably 200 to 300 ° C. When the process is performed, the effect of narrowing the particle size distribution of polyarylene sulfide and increasing the median diameter of the polyarylene sulfide powder tends to be large. Even when the organic polar solvent is distilled off in the temperature range of 140 to 180 ° C., the effect of increasing the median diameter of the polyarylene sulfide powder is small, but the polyarylene sulfide component having a median diameter of 10 μm or less is decreased. However, the particle size distribution tends to be narrowed. Considering that polyarylene sulfide tends to be insoluble in organic polar solvents in this temperature range and that linear polyarylene sulfide oligomer tends to be soluble in this temperature range, it reacts in this temperature range. It can be inferred that most of the components are linear polyarylene sulfide oligomers, and therefore, the polyarylene sulfide component having a median diameter of 10 μm or less is highly likely to be a linear polyarylene sulfide oligomer. Here, the median diameter of polyarylene sulfide can be measured using, for example, a particle size distribution measuring apparatus “SALD-7000” (manufactured by Shimadzu Corporation) by a laser diffraction / scattering method. The particle size distribution of the polyarylene sulfide was evaluated based on the standard deviation of the obtained particle size distribution graph of the polyarylene sulfide.

  In addition, before distilling off the organic polar solvent, it is possible to perform an operation of removing a component insoluble at a temperature at which the polyarylene sulfide is dissolved by solid-liquid separation (d). By performing this operation, the viscosity of the mixture (b) obtained by distilling off the organic polar solvent tends to be lowered, and the operability tends to be improved.

  Here, the temperature at which solid-liquid separation (d) is performed is not particularly limited as long as the polyarylene sulfide is dissolved, but is preferably in the range of 200 to 350 ° C, more preferably in the range of 220 to 300 ° C, and 230 A range of ˜280 ° C. is more preferable. In such a temperature range, polyarylene sulfide and cyclic polyarylene sulfide are less likely to be decomposed or altered, and organic polar solvents are less likely to be degraded or altered. In such a preferable temperature range, the solubility of polyarylene sulfide in an organic polar solvent is improved, so that it becomes easy to form a uniform solution component, and the viscosity of the solution component tends to decrease as the temperature increases. The separability in the solid-liquid separation operation tends to be improved.

  Although there is no restriction | limiting in particular in the pressure at the time of performing solid-liquid separation (d) in the temperature range where polyarylene sulfide becomes soluble, 2.0 MPa or less is preferable at a gauge pressure, and 1.0 MPa or less is more preferable. In general, as the pressure increases, it is necessary to increase the pressure resistance of the equipment that performs solid-liquid separation, and such equipment must have a high degree of sealing performance at each part constituting it, and inevitably equipment. Since the cost increases, it is preferable to perform solid-liquid separation at a lower pressure.

  In addition, the method for performing solid-liquid separation (d) is not particularly limited, and a known method can be employed. Pressure filtration or vacuum filtration, which is filtration using a filter, or separation based on a difference in specific gravity between a solid content and a solution. Centrifugation, sedimentation, and a combination of these can be employed. A decanter separation method in which sedimentation separation is performed before the filtration operation is also a preferable method. The filter used for filtration operation should just be stable on the conditions which perform solid-liquid separation (d), for example, a wire sieve and a sintered plate can be used conveniently. In addition, the mesh size or pore size of this filter varies widely depending on the viscosity, pressure, temperature, particle size of the solid component in the slurry, and purity of the resulting filtrate (solid content). Can be adjusted.

(12) Recovery of polyarylene sulfide In the present invention, the mixture (b) obtained by distilling off the organic polar solvent is subjected to solid-liquid separation (c) in a temperature region where the polyarylene sulfide is insoluble, and insoluble. Polyarylene sulfide is recovered as a component, and cyclic polyarylene sulfide is recovered as a soluble component. The temperature at which the solid-liquid separation (c) is performed is not particularly limited as long as the polyarylene sulfide is insoluble, but a temperature range of 20 to 200 ° C is preferable, a range of 50 to 150 ° C is more preferable, and a temperature of 80 to 120 ° C is preferable. A range can be illustrated more preferably. In this preferred temperature range, polyarylene sulfide tends to be present as a solid, while cyclic polyarylene sulfide tends to be dissolved in an organic polar solvent. Therefore, by performing solid-liquid separation in this temperature range, the polyarylene sulfide can be easily separated as a solid content and the cyclic polyarylene sulfide is dissolved in an organic polar solvent.

  There is no limitation on the pressure when performing solid-liquid separation (c), and for example, the pressure range in solid-liquid separation (d) can be exemplified, but solid-liquid separation (c) is lower than solid-liquid separation (d). Since the solid-liquid separation operation is performed at the temperature, the operation can be performed under a pressure lower than that of the solid-liquid separation (d). Specifically, a pressure of 2.0 MPa or less can be exemplified as a preferable pressure range, more preferably 1.0 MPa or less, still more preferably 0.8 MPa or less, and even more preferably 0.5 MPa or less. In general, as the pressure increases, it is necessary to increase the pressure resistance of the equipment that performs solid-liquid separation, and such equipment must have a high degree of sealing performance at each part constituting it, and inevitably equipment. Expenses will increase. In the preferred pressure range, generally available solid-liquid separation equipment can be used.

  Further, the method for performing solid-liquid separation (c) is not particularly limited, and the method exemplified in the above-mentioned solid-liquid separation (d) can be employed. Pressure filtration or vacuum filtration, which is filtration using a filter, solid content Centrifugation and sedimentation separation, which is a separation based on the difference in specific gravity between the solution and solution, and a combination of these methods can be employed. A decanter separation method in which sedimentation separation is performed before the filtration operation is also a preferable method. The filter used for the filtration operation is not particularly limited as long as it is stable under the conditions for solid-liquid separation. For example, commonly used filter media such as a wire mesh filter, a sintered plate, a filter cloth, and filter paper can be suitably used. In addition, the pore size of this filter can be adjusted over a wide range depending on the viscosity, pressure, temperature of the slurry used for the solid-liquid separation operation, the particle size of the solid component in the slurry, and the purity of the resulting filtrate (solid content). Yes. In particular, the particle diameter of the polyarylene sulfide recovered as a solid content from the slurry in the solid-liquid separation (c) operation, that is, the mesh diameter depending on the particle diameter of the solid content present in the slurry subjected to the solid-liquid separation (c). Alternatively, it is effective to select a filter pore size such as a pore size. In addition, the average particle diameter (median diameter) of the polyarylene sulfide in the slurry subjected to solid-liquid separation (c) can vary widely depending on the composition, temperature, concentration, etc. of the slurry, but as far as the present inventors know, The average particle diameter tends to be 1 to 200 μm. Therefore, 0.1-100 micrometers can be illustrated as a preferable average hole diameter of the hole diameter of a filter, 0.25-20 micrometers is preferable, and 0.5-15 micrometers can be illustrated as a more preferable range.

  According to the solid-liquid separation (c) here, most of the polyarylene sulfide contained in the mixture (b) can be separated as a solid content, preferably 80% or more, more preferably 90% or more, still more preferably Can recover 95% or more as solids. In addition, when the solid polyarylene sulfide separated by solid-liquid separation contains an organic polar solvent solution (mother liquor) containing cyclic polyarylene sulfide, the solid content should be washed with a fresh solvent. It is also possible to reduce the residual amount of cyclic polyarylene sulfide in the solid content. As this method, there are a method of adding a fresh solvent on a filter in which a solid cake is laminated and solid-liquid separation, a method of adding a fresh solvent to a solid cake and stirring to make a slurry, and then a solid-liquid separation. As examples, the conditions for performing these operations are preferably performed in accordance with the preferable conditions employed for the solid-liquid separation (c) described above. In addition, the solvent used here should just be a thing in which cyclic polyarylene sulfide can melt | dissolve, Preferably an organic polar solvent can be illustrated.

  Further, the polyarylene sulfide recovered as a solid component by the solid-liquid separation (c) has a significantly reduced content of the linear polyarylene sulfide oligomer. In this case, since the solid component contains an alkali metal halide salt, the alkali metal halide salt can be removed by a known method. Examples of the removing method include a method of contacting with a second solvent in which the alkali metal halide salt is soluble.

  As the second solvent used when removing the alkali metal halide salt from the solid component, a solvent in which the alkali metal halide salt is soluble is preferable, for example, alcohol solvents such as methanol and ethanol and water can be exemplified, and water is particularly preferable. preferable.

  There is no particular limitation on the temperature at which the alkali metal halide salt is removed from the solid component, but the upper limit is preferably set to the reflux condition temperature under normal pressure of the second solvent to be used. 20-100 degreeC can be illustrated as a preferable temperature range, More preferably, 25-80 degreeC can be illustrated.

  As a method of bringing the solid component into contact with the second solvent, a method in which the second solvent is added to the filter on which the solid component is laminated to perform solid-liquid separation, or a method in which the second solvent is added to the solid component and stirred. An example is a method of solid-liquid separation after slurrying. Examples of the solid-liquid separation method include separation by filtration, centrifugation, and decantation. It is also possible to bring the polyarylene sulfide thus obtained into contact with the second solvent again to further reduce the content of the alkali metal halide salt.

  Since the polyarylene sulfide thus obtained contains the second solvent, it can be dried under normal pressure and / or reduced pressure as desired. The drying temperature is preferably in the range of 50 to 200 ° C, more preferably in the range of 70 to 150 ° C. The drying atmosphere may be any of an inert atmosphere such as nitrogen, helium, and argon, a reduced pressure, an oxidizing atmosphere such as oxygen and air, and a mixed atmosphere of air and nitrogen. It is also a preferred method to dry under reduced pressure after removing most of the solvent and then dry again under reduced pressure. The drying time is preferably 0.5 to 50 hours, more preferably 1 to 30 hours, and further preferably 1 to 20 hours.

  The polyarylene sulfide obtained by the present invention is excellent in heat resistance, chemical resistance, flame retardancy, electrical properties and mechanical properties. In particular, the remarkable effect manifested by the present invention is that the amount of low molecular weight components such as polyarylene sulfide oligomer contained in polyarylene sulfide is remarkably reduced as compared with polyarylene sulfide obtained by a known method. Thus, the amount of gel and gas generation is small, and the moldability is particularly excellent, and not only injection molding but also extrusion molding such as sheet, film, fiber and pipe can be formed by extrusion molding.

(13) Recovery of cyclic polyarylene sulfide A cyclic polyarylene sulfide mixture can be obtained by removing the organic polar solvent from the filtrate component obtained by the solid-liquid separation (c). There is no particular limitation on the method for obtaining the cyclic polyarylene sulfide mixture by removing the organic polar solvent from the filtrate component, and the filtrate component is contacted with a solvent having low solubility in the polyarylene sulfide component and miscible with the organic polar solvent, A method of recovering the cyclic polyarylene sulfide mixture, a solvent having a low solubility in the polyarylene sulfide component and miscible with the organic polar solvent after removing part or most of the organic polar solvent in the filtrate by an operation such as distillation; Contacting, recovering the cyclic polyarylene sulfide mixture, cooling the filtrate to precipitate the cyclic polyarylene sulfide mixture, recovering the deposited cyclic polyarylene sulfide mixture, heating the filtrate at normal pressure or lower To remove the organic polar solvent and recycle the cyclic polyarylene sulfide mixture. How to, and the like. Among them, after removing a part or most of the organic polar solvent by an operation such as distillation, it is brought into contact with a solvent that has low solubility in the polyarylene sulfide component and is miscible with the organic polar solvent, to thereby obtain a cyclic polyarylene sulfide mixture. A method of recovering is preferable. In addition, the solvent having such characteristics is generally a relatively polar solvent, and the preferred solvent varies depending on the type of organic polar solvent used, but it is not limited. For example, water, methanol, ethanol, propanol, isopropanol, butanol Alcohols typified by hexanol, acetone, ketones typified by methyl ethyl ketone, ethyl acetate, acetates typified by butyl acetate can be exemplified, and water, methanol and acetone are preferred from the viewpoint of availability and economy, Water is particularly preferred. By performing the treatment with such a solvent, it is possible to reduce the amount of the organic polar solvent or by-product salt contained in the cyclic polyarylene sulfide mixture. Since the cyclic polyarylene sulfide mixture is precipitated as a solid component by this treatment, the cyclic polyarylene sulfide mixture can be recovered using a known solid-liquid separation method. Examples of the solid-liquid separation method include separation by filtration, centrifugation, and decantation. Note that these series of treatments can be repeated several times as necessary, and this tends to further reduce the amount of the organic polar solvent and by-product salt contained in the cyclic polyarylene sulfide mixture. In the method of recovering the cyclic polyarylene sulfide mixture by contacting with a solvent that is poorly soluble in the polyarylene sulfide component and miscible with the organic polar solvent, it is at least 70% by weight, preferably 90% by weight or more, more preferably It is desirable to remove 95% by weight or more of the organic polar solvent.

  Moreover, as another preferable method of removing the organic polar solvent from the filtrate, a method of removing the organic polar solvent by heating at normal pressure or lower can be exemplified. The filtrate containing the cyclic polyarylene sulfide obtained as described above may contain a solid depending on the temperature. In this case, the solid is soluble in the organic polar solvent when the organic polar solvent is removed. It is desirable to recover with the components. In the method of removing the organic polar solvent by heating at normal pressure or lower, the removal of the organic polar solvent is at least 50 wt% or more, preferably 70 wt% or more, more preferably 90 wt% or more, and even more preferably 95 wt%. It is desirable to remove more than% organic polar solvent. Although the temperature at which the organic polar solvent is removed by heating depends on the characteristics of the organic polar solvent to be used, it cannot be uniquely limited, but a range of 20 to 150 ° C, preferably 40 to 120 ° C can be selected. In addition, the pressure for removing the organic polar solvent is preferably equal to or lower than normal pressure, which makes it possible to remove the organic polar solvent at a lower temperature.

  The cyclic polyarylene sulfide mixture thus obtained has a high purity and contains generally 50% by weight or more, preferably 60% by weight or more, more preferably 70% by weight or more of the cyclic polyarylene sulfide. Industrially having a different property from linear polyarylene sulfide and having high utility value.

  The present invention will be specifically described below with reference to examples. These examples are illustrative and not limiting.

<Molecular weight measurement of polyarylene sulfide>
The molecular weight of polyarylene sulfide was calculated in terms of polystyrene by gel permeation chromatography (GPC), which is a type of size exclusion chromatography (SEC). The GPC measurement conditions are described below.
Equipment: Senshu Science SSC-7100
Column name: Senshu Science GPC3506
Eluent: 1-chloronaphthalene detector: differential refractive index detector Column temperature: 210 ° C
Pre-constant temperature: 250 ° C
Pump bath temperature: 50 ° C
Detector temperature: 210 ° C
Flow rate: 1.0 mL / min
Sample injection amount: 300 μL (slurry: about 0.2% by weight)

<Linear polyarylene sulfide oligomer content of polyarylene sulfide>
The content of the linear polyarylene sulfide oligomer of the polyarylene sulfide was estimated as a weight fraction of the soluble portion of hot chloroform by extracting the polyarylene sulfide with hot chloroform. The extraction operation was performed by the following method.
-5 g of polyarylene sulfide was subjected to Soxhlet extraction with 100 g of chloroform at a bath temperature of 85 ° C. for 5 hours.
-Chloroform was distilled off from the extract obtained using the rotary evaporator.
Subsequently, vacuum drying was performed at 70 ° C. for 3 hours, the weight of the obtained solid content was determined, and the weight fraction with respect to the weight of polyarylene sulfide was calculated.

<Measurement of cyclic polyarylene sulfide content>
The cyclic polyarylene sulfide content in the cyclic polyarylene sulfide mixture was calculated by performing quantitative analysis by high performance liquid chromatography (HPLC).

The measurement conditions for HPLC are shown below.
Apparatus: Shimadzu Corporation LC-10Avp series Column: Mightysil RP-18 GP 150-4.6 (5 μm)
Detector: Photodiode array detector (UV = 270 nm)

<Measurement of consumption of dihalogenated aromatic compounds>
The consumption of the dihalogenated aromatic compound as a reaction raw material was calculated by performing quantitative analysis by gas chromatography (GC) analysis. GC measurement conditions are shown below.
Device: GC17-A manufactured by Shimadzu Corporation
Column: TC-17 0.32 mmφ × 60 m 0.5 μm thickness (manufactured by GL Sciences)
Carrier gas flow rate: 1.44 mL / min
Column inlet pressure: 140 kPa
Column oven: 250 ° C
Split ratio: 10: 1
Detector: Hydrogen flame ionization detection method (FID method)
Injection volume: 5 μL (Injection of reaction solution diluted about 10 times with chloroform)

<Measurement of average particle size of polyarylene sulfide>
The measurement conditions for the average particle diameter of polyarylene sulfide are shown below.
Apparatus: Shimadzu laser diffraction particle size distribution analyzer (SALD-7000)
Dispersion: N-methyl-2-pyrrolidone (NMP)

[Reference Example 1]
In a 1 liter autoclave equipped with a stirrer, 23.54 g of a 48 wt% aqueous solution of sodium hydrosulfide (11.30 g (0.202 mol) of sodium hydrosulfide) and 17.50 g of a 48 wt% aqueous solution of sodium hydroxide ( Sodium hydroxide 8.40 g (0.210 mol)), N-methyl-2-pyrrolidone (NMP) 500 mL, and p-dichlorobenzene (p-DCB) 29.40 g (0.20 mol) were charged.

  The reaction vessel was sealed under nitrogen gas at room temperature and normal pressure, and then heated from room temperature to 200 ° C. over 25 minutes while stirring at 400 rpm. Next, the temperature was raised to 250 ° C. over 35 minutes, and a reaction was performed at 250 ° C. for 2 hours to prepare a mixture (a).

  As a result of analyzing the obtained contents by gas chromatography and high performance liquid chromatography, it was found that the consumption rate of monomer p-DCB was 98.1% and the production rate of cyclic polyphenylene sulfide was 16.6%. . This shows that the mixture (a) prepared by this method contains 20 parts by weight of cyclic polyphenylene sulfide with respect to 100 parts by weight of polyphenylene sulfide.

[Reference Example 2]
After diluting 500 g of the contents obtained in Reference Example 1 with about 1500 g of ion-exchanged water, the precipitated components were collected by filtration with a glass filter. The filter-on component was dispersed in about 300 g of ion-exchanged water, stirred at 70 ° C. for 30 minutes, and again subjected to the same filtration and recovery operation three times in total to obtain a white solid. This was subjected to vacuum drying at 80 ° C. for 8 hours to obtain a dry solid.

  The obtained solid material was charged into a cylindrical filter paper, and subjected to Soxhlet extraction for about 5 hours using chloroform as a solvent, thereby removing linear polyphenylene sulfide oligomer contained in the solid content.

  The solid component remaining in the cylindrical filter paper after the extraction operation was subjected to vacuum drying at 70 ° C. for 8 hours to obtain about 14.5 g of a dry solid. As a result of analysis, it was a linear polyphenylene sulfide and the weight average molecular weight was 12,800 from the absorption spectrum in infrared spectroscopic analysis. The polyphenylene sulfide obtained here was used in Reference Example 3.

[Reference Example 3]
In an autoclave equipped with a stirrer, 1.73 g of polyphenylene sulfide having a weight average molecular weight of 12800 prepared according to Reference Example 2 (sulfur component amount 0.16 mol) and 4.68 g of 48 wt% aqueous solution of sodium hydrosulfide (hydrosulfide) Sodium 2.24 g (0.04 mol)), 48 wt% aqueous solution of sodium hydroxide 4.67 g (sodium hydroxide 2.00 g (0.05 mol)), NMP 500 mL, and p-dichlorobenzene 5. 88 g (0.04 mol) was charged. The total sulfur component derived from polyphenylene sulfide and sodium hydrosulfide was 0.20 mol, and the amount of solvent per mol of sulfur component in the mixture was about 2.50 L.

  The reaction vessel was sealed under nitrogen gas at room temperature and normal pressure, and then heated from room temperature to 200 ° C. over about 1 hour with stirring at 400 rpm. Subsequently, it heated up to 270 degreeC over about 0.5 hour. Reaction was performed at 270 degreeC for 1 hour, and the mixture (a) was prepared.

  As a result of analyzing the obtained contents by gas chromatography and high performance liquid chromatography, the consumption rate of monomer p-DCB was 87.2%, and the production rate of cyclic polyphenylene sulfide with respect to the charged monomer (p-DCB) was about It was found that the production rate of cyclic polyphenylene sulfide was 11.2% assuming that all sulfur components in the mixture were converted to cyclic polyphenylene sulfide. From this result, it is understood that the mixture (a) prepared by this method contains 13 parts by weight of cyclic polyphenylene sulfide with respect to 100 parts by weight of polyphenylene sulfide.

[Example 1]
The mixture (a) obtained by the method described in Reference Example 1 was extracted, charged into an autoclave equipped with a valve, and heated so that the internal temperature was 250 ° C. Next, the extraction valve was gradually opened while maintaining the internal temperature at 250 ° C., and 380 g of the solvent was distilled off over 40 minutes. After completion of the solvent distillation, the autoclave was cooled to near room temperature, and the mixture (b) was recovered.

  Analysis of the distilled solvent by gas chromatography revealed that it contained about 355 g of NMP. Thereby, it was found that the mixture (b) contained about 0.75 liters of NMP per mole of sulfur atoms.

  The recovered mixture (b) was heated and stirred under nitrogen so that the temperature of the reaction solution was 100 ° C. After maintaining at 100 ° C. for 20 minutes, solid-liquid separation (c) was performed using a glass filter having a pore diameter of 10 μm. The solid-liquid separation (c) took about 5 minutes.

  The filtrate component obtained by solid-liquid separation (c) was dropped into about 3 times the amount of methanol, and the precipitated methanol-insoluble component was recovered. The obtained solid component was dried under reduced pressure at 80 ° C. for 8 hours to obtain 3.56 g of a cyclic polyphenylene sulfide mixture (yield 16.5%).

  When the obtained cyclic polyphenylene sulfide mixture was analyzed by high performance liquid chromatography, it was found to contain 83% by weight of cyclic polyphenylene sulfide.

  Further, the component separated as a solid content by solid-liquid separation (c) was added to about 5 times amount of deionized water and dispersed, and then heated to 70 ° C. and stirred for 15 minutes. The slurry was filtered through a glass filter (average pore diameter of 10 to 16 μm) to obtain a solid content. The obtained solid content was dispersed in about 5 times amount of deionized water, and the obtained solid content was vacuum dried at 120 ° C. for 3 hours to obtain about 17.50 g of a dry solid.

  As a result of analyzing the obtained polyphenylene sulfide, it was found to be a polymer having a weight average molecular weight of 16000. Further, when the content of the linear polyarylene sulfide oligomer contained in the polyphenylene sulfide was measured by the method described above, it was found to be 0.15%. When the particle size distribution of polyphenylene sulfide was measured, it was found that the median diameter was 22 μm and the standard deviation of the particle size distribution was 0.53.

[Example 2]
The mixture (a) obtained by the method described in Reference Example 3 was extracted, charged into an autoclave equipped with a valve, and heated to an internal temperature of 250 ° C. Next, the extraction valve was gradually opened while maintaining the internal temperature at 250 ° C., and 390 g of the solvent was distilled off over 40 minutes. After completion of the solvent distillation, the autoclave was cooled to near room temperature, and the mixture (b) was recovered.

  Analysis of the distilled solvent by gas chromatography revealed that it contained about 365 g of NMP. This showed that mixture (b) contained about 0.74 liters of NMP per mole of sulfur atoms.

  The recovered mixture (b) was heated and stirred under nitrogen so that the temperature of the reaction solution was 100 ° C. After maintaining at 100 ° C. for 20 minutes, solid-liquid separation (c) was performed using a glass filter having a pore diameter of 10 μm. The solid-liquid separation (c) took about 6 minutes.

  The filtrate component obtained by solid-liquid separation (c) was dropped into about 3 times the amount of methanol, and the precipitated methanol-insoluble component was recovered. The obtained solid component was dried at 80 ° C. under reduced pressure for 8 hours to obtain 2.35 g of a cyclic polyphenylene sulfide mixture (yield 10.9%).

  When the obtained cyclic polyphenylene sulfide mixture was analyzed by high performance liquid chromatography, it was found to contain 81% by weight of cyclic polyphenylene sulfide.

  Further, the component separated as a solid content by solid-liquid separation (c) was added to about 5 times amount of deionized water and dispersed, and then heated to 70 ° C. and stirred for 15 minutes. The slurry was filtered through a glass filter (average pore diameter of 10 to 16 μm) to obtain a solid content. The obtained solid content was dispersed in about 5 times amount of deionized water, and the obtained solid content was vacuum dried at 120 ° C. for 3 hours to obtain about 17.30 g of a dry solid.

  As a result of analyzing the obtained polyphenylene sulfide, it was found that the polymer had a weight average of 15300. Moreover, when the linear polyarylene sulfide oligomer content contained in polyphenylene sulfide was measured by the method described above, it was found to be 0.20%. When the particle size distribution of polyphenylene sulfide was measured, it was found that the median diameter was 20 μm and the standard deviation of the particle size distribution was 0.56.

[Comparative Example 1]
The mixture (a) obtained in Reference Example 1 was heated and stirred under nitrogen so that the temperature of the reaction solution was 100 ° C. After maintaining at 100 ° C. for 20 minutes, solid-liquid separation (c) was performed using a glass filter having a pore diameter of 10 μm. The solid-liquid separation (c) took about 70 minutes.

  The filtrate component obtained by solid-liquid separation (c) was dropped into about 3 times weight of methanol, and the precipitated methanol-insoluble component was recovered. The obtained solid component was dried at 80 ° C. under reduced pressure for 8 hours to obtain 3.89 g of a cyclic polyphenylene sulfide mixture (yield 18%).

  When the obtained cyclic polyphenylene sulfide mixture was analyzed by high performance liquid chromatography, it was found to contain 76% by weight of cyclic polyphenylene sulfide.

  Further, the component separated as a solid content by solid-liquid separation (c) was added to about 5 times amount of deionized water and dispersed, and then heated to 70 ° C. and stirred for 15 minutes. The slurry was filtered through a glass filter (average pore diameter of 10 to 16 μm) to obtain a solid content. The operation of dispersing the obtained solid content in about 5 times amount of deionized water, heating to 70 ° C., stirring for 15 minutes and filtering to obtain the solid content was repeated three times. The obtained solid was subjected to vacuum drying at 120 ° C. for 3 hours to obtain about 17.06 g of a dry solid.

  As a result of analyzing the obtained polyphenylene sulfide, it was found to be a polymer having a weight average molecular weight of 11,000. Further, when the content of linear polyarylene sulfide oligomer contained in polyphenylene sulfide was measured by the method described above, it was found to be 3.5%. Further, when the particle size distribution measurement of polyphenylene sulfide was performed, it was found that the median diameter was 12 μm and the standard deviation of the particle size distribution was 0.764, and the distribution was very wide.

  Comparison of Example 1 and Comparative Example 1 shows that the organic polar solvent is distilled off after completion of the reaction, thereby increasing the purity of the cyclic polyarylene sulfide, increasing the weight average molecular weight of the polyarylene sulfide, and polyarylene. The content of the linear polyarylene sulfide oligomer contained in the sulfide is reduced, the median diameter of the polyarylene sulfide is increased, the particle size distribution is narrowed, and the efficiency of the solid-liquid separation (c) is greatly improved. I understand.

[Example 3]
The mixture (a) obtained by the method described in Reference Example 1 was extracted, charged into an autoclave equipped with a valve, and heated so that the internal temperature was 200 ° C. Next, 378 g of the solvent was distilled off over 70 minutes under reduced pressure while maintaining the internal temperature at 200 ° C. After completion of evaporation of the solvent, the autoclave was cooled to near room temperature, and the mixture (b) was recovered.

  Analysis of the distilled solvent by gas chromatography revealed that it contained about 354 g of NMP. Thereby, it was found that the mixture (b) contained 0.78 liters of NMP per mole of sulfur atoms.

  Next, the mixture (b) was heated and stirred under nitrogen so that the temperature of the reaction solution was 100 ° C. After maintaining at 100 ° C. for 20 minutes, solid-liquid separation (c) was performed using a glass filter having a pore diameter of 10 μm. The solid-liquid separation (c) took about 23 minutes.

  The filtrate component obtained by solid-liquid separation (c) was dropped into about 3 times weight of methanol, and the precipitated methanol-insoluble component was recovered. The obtained solid component was dried at 80 ° C. under reduced pressure for 8 hours to obtain 3.75 g of a cyclic polyphenylene sulfide mixture (yield 17.4%).

  When the obtained cyclic polyphenylene sulfide mixture was analyzed by high performance liquid chromatography, it was found to contain 78% by weight of cyclic polyphenylene sulfide.

  Further, the component separated as a solid content by solid-liquid separation (c) was added to about 5 times amount of deionized water and dispersed, and then heated to 70 ° C. and stirred for 15 minutes. The slurry was filtered through a glass filter (average pore diameter of 10 to 16 μm) to obtain a solid content. The operation of dispersing the obtained solid content in about 5 times amount of deionized water, heating to 70 ° C., stirring for 15 minutes and filtering to obtain the solid content was repeated three times. The obtained solid was subjected to vacuum drying at 120 ° C. for 3 hours to obtain 17.48 g of a dry solid.

  As a result of analyzing the obtained polyphenylene sulfide, it was found to be a polymer having a weight average molecular weight of 12500. Moreover, when the linear polyarylene sulfide oligomer content rate contained in polyphenylene sulfide was measured by the method shown above, it was found to be 1.9%. When the particle size distribution of polyphenylene sulfide was measured, it was found that the median diameter was 15 μm and the standard deviation of the particle size distribution was 0.63.

  Comparing Example 1 and Comparative Example 1, the purity of the cyclic polyarylene sulfide is increased by distilling off the organic polar solvent after completion of the reaction, regardless of the temperature at which the organic polar solvent is distilled off. The weight average molecular weight of the sulfide is increased, the content of the linear polyarylene sulfide oligomer contained in the polyarylene sulfide is reduced, the median diameter of the polyarylene sulfide is increased, and the efficiency of the solid-liquid separation (c) is improved. However, it can be seen from a comparison between Example 1 and Example 3 that these effects tend to appear more prominently when the organic polar solvent is distilled off in a preferred temperature range.

[Example 4]
The mixture (a) obtained by the method described in Reference Example 1 was extracted, charged into an autoclave equipped with a valve, and heated so that the internal temperature was 150 ° C. Next, 380 g of the solvent was distilled off over 120 minutes under reduced pressure while maintaining the internal temperature at 150 ° C. After completion of the evaporation of the solvent, the autoclave was cooled to near room temperature, and the mixture (b) was recovered.

  Analysis of the distilled solvent by gas chromatography revealed that it contained about 353 g of NMP. Thereby, it was found that the mixture (b) contained 0.78 liters of NMP per mole of sulfur atoms.

  Next, the mixture (b) was heated and stirred under nitrogen so that the temperature of the reaction solution was 100 ° C. After maintaining at 100 ° C. for 20 minutes, solid-liquid separation (c) was performed using a glass filter having a pore diameter of 10 μm. The solid-liquid separation (c) took about 45 minutes.

  The filtrate component obtained by solid-liquid separation (c) was dropped into about 3 times the amount of methanol, and the precipitated methanol-insoluble component was recovered. The obtained solid component was dried at 80 ° C. under reduced pressure for 8 hours to obtain 3.78 g of a cyclic polyarylene sulfide mixture (yield 17.6%).

  When the obtained cyclic polyarylene sulfide mixture was analyzed by high performance liquid chromatography, it was found to contain 78% by weight of cyclic polyarylene sulfide.

  Further, the component separated as a solid content by solid-liquid separation (c) was added to about 5 times amount of deionized water and dispersed, and then heated to 70 ° C. and stirred for 15 minutes. The slurry was filtered through a glass filter (average pore diameter of 10 to 16 μm) to obtain a solid content. The operation of dispersing the obtained solid content in about 5 times amount of deionized water, heating to 70 ° C., stirring for 15 minutes and filtering to obtain the solid content was repeated three times. The obtained solid was subjected to vacuum drying at 120 ° C. for 3 hours to obtain 17.4 g of a dry solid.

  As a result of analyzing the obtained polyphenylene sulfide, it was found to be a polymer having a weight average molecular weight of 11,000. Moreover, when the linear polyarylene sulfide oligomer content rate contained in polyphenylene sulfide was measured by the method shown above, it was found to be 2.5%. When the particle size distribution of polyphenylene sulfide was measured, it was found that the median diameter was 12 μm and the standard deviation of the particle size distribution was 0.65.

  In comparison with Comparative Example 1, even when the organic polar solvent is distilled off in the temperature range where the polyarylene sulfide is precipitated, the purity of the cyclic polyarylene sulfide is increased and the particle size distribution of the polyarylene sulfide is narrowed. Therefore, it turns out that the efficiency of solid-liquid separation (c) improves. On the other hand, by comparison with Example 1, the effect of reducing the content of linear polyarylene sulfide oligomer contained in the recovered polyarylene sulfide oligomer is greater when the organic polar solvent is distilled off in a preferable temperature range. I understand.

[Example 5]
The mixture (a) obtained by the method described in Reference Example 1 was extracted, charged into an autoclave equipped with a valve, and heated so that the internal temperature was 250 ° C. Subsequently, 440 g of the solvent was distilled off over 50 minutes while maintaining the internal temperature at 250 ° C. After completion of the solvent distillation, the autoclave was cooled to near room temperature to obtain a mixture (b). Analysis of the distilled solvent by gas chromatography revealed that it contained about 415 g of NMP. Thus, it was found that future product (b) contains about 0.47 liters of NMP per mole of sulfur atoms.

  Next, the mixture (b) was heated and stirred under nitrogen so that the temperature of the reaction solution was 100 ° C. After maintaining at 100 ° C. for 20 minutes, solid-liquid separation (c) was performed using a glass filter having a pore diameter of 10 μm. The solid-liquid separation (c) took about 3 minutes.

  The filtrate component obtained by solid-liquid separation (c) was dropped into about 3 times weight of methanol, and the precipitated methanol-insoluble component was recovered. The obtained solid component was dried at 80 ° C. under reduced pressure for 8 hours to obtain 3.46 g of a cyclic polyphenylene sulfide mixture (yield 16.1%).

  When the obtained cyclic polyphenylene sulfide mixture was analyzed by high performance liquid chromatography, it was found to contain 86% by weight of cyclic polyphenylene sulfide.

  The component separated as a solid content by solid-liquid separation (c) was added to about 5 times amount of deionized water and dispersed, and then heated to 70 ° C. and stirred for 15 minutes. The slurry was filtered through a glass filter (average pore diameter of 10 to 16 μm) to obtain a solid content. The operation of dispersing the obtained solid content in about 5 times amount of deionized water, heating to 70 ° C., stirring for 15 minutes and filtering to obtain the solid content was repeated three times. The obtained solid was subjected to vacuum drying at 120 ° C. for 3 hours to obtain about 17.55 g of a dry solid.

  As a result of analyzing the obtained polyphenylene sulfide, it was found to be a polymer having a weight average molecular weight of 18,000. Moreover, when the linear polyarylene sulfide oligomer content rate contained in polyphenylene sulfide was measured by the method shown above, it was found to be 0.08%. When the particle size distribution of polyphenylene sulfide was measured, it was found that the median diameter was 42 μm and the standard deviation of the particle size distribution was 0.57.

  By comparing Example 1 and Example 4, the amount of the organic polar solvent distilled off was increased, and the amount of the organic polar solvent per mole of sulfur atoms contained in the mixture (b) was reduced, thereby cyclic polyarylene. It can be seen that the purity of sulfide increases, the weight average molecular weight of polyarylene sulfide increases, and the median diameter of polyarylene sulfide tends to increase.

[Example 6]
The mixture (a) obtained by the method described in Reference Example 1 was extracted, charged into an autoclave equipped with a valve, and heated so that the internal temperature was 250 ° C. Next, while keeping the internal temperature at 250 ° C., the extraction valve was gradually opened, and about 325 g of the solvent was distilled off over 38 minutes (distilled solvent (1)). Thereafter, the mixture was gradually cooled to an internal temperature of 140 ° C., and 115 g of the solvent was distilled off at an internal temperature of 140 ° C. under reduced pressure for 50 minutes (distilled solvent (2)). After completion of the solvent distillation, the autoclave was cooled to near room temperature, and the mixture (b) was recovered.

  Analysis of the distilled solvent (1) by gas chromatography revealed that it contained about 300 g of NMP. Thereby, it turned out that the reaction liquid after distilling a solvent off at 250 degreeC contains about 1.03 liters of NMP per 1 mol of sulfur atoms. It can also be seen that the recovered mixture (b) contains about 0.47 liters of NMP per mole of sulfur atoms.

  The recovered mixture (b) was heated and stirred under nitrogen so that the temperature of the reaction solution was 100 ° C. After maintaining at 100 ° C. for 20 minutes, solid-liquid separation (c) was performed using a glass filter having a pore diameter of 10 μm. The solid-liquid separation (c) took about 7 minutes.

  The filtrate component obtained by solid-liquid separation (c) was dropped into about 3 times the amount of methanol, and the precipitated methanol-insoluble component was recovered. The obtained solid component was dried at 80 ° C. under reduced pressure for 8 hours to obtain 3.63 g of a cyclic polyphenylene sulfide mixture (yield 16.8%).

  When the obtained cyclic polyphenylene sulfide mixture was analyzed by high performance liquid chromatography, it was found to contain 82% by weight of cyclic polyphenylene sulfide.

  Further, the component separated as a solid content by solid-liquid separation (c) was added to about 5 times amount of deionized water and dispersed, and then heated to 70 ° C. and stirred for 15 minutes. The slurry was filtered through a glass filter (average pore diameter of 10 to 16 μm) to obtain a solid content. The obtained solid content was dispersed in about 5 times the amount of deionized water, and the obtained solid content was subjected to vacuum drying at 120 ° C. for 3 hours to obtain about 17.2 g of a dry solid.

  As a result of analyzing the obtained polyphenylene sulfide, it was found to be a polymer having a weight average molecular weight of 16000. Further, when the content of the linear polyarylene sulfide oligomer contained in the polyphenylene sulfide was measured by the method described above, it was found to be 0.1%. When the particle size distribution of polyphenylene sulfide was measured, it was found that the median diameter was 28 μm and the standard deviation of the particle size distribution was 0.55.

Claims (11)

A mixture comprising at least polyarylene sulfide, cyclic polyarylene sulfide and an organic polar solvent, wherein the cyclic polyarylene sulfide is 6 parts by weight or more with respect to 100 parts by weight of the polyarylene sulfide. A method for recovering arylene sulfide and polyarylene sulfide, wherein the organic polar solvent is distilled off from the mixture (a) to prepare a mixture (b) containing at least the polyarylene sulfide, the cyclic polyarylene sulfide and the organic polar solvent. And a process for solid-liquid separation (c) of the mixture (b) in a temperature range in which the polyarylene sulfide is insoluble, and a method for recovering the cyclic polyarylene sulfide and the polyarylene sulfide. As the mixture (a), a mixture containing at least a sulfidizing agent, a dihalogenated aromatic compound and an organic polar solvent is used by heating at least 1.25 liters of an organic polar solvent with respect to 1 mol of a sulfur component in the mixture. The cyclic polyarylene sulfide and the method for recovering polyarylene sulfide according to claim 1, wherein the mixture obtained by the reaction is used. As the mixture (a), a mixture containing at least polyarylene sulfide, a sulfidizing agent, a dihalogenated aromatic compound and an organic polar solvent is used in an amount of 1.25 liters or more of an organic polar solvent with respect to 1 mol of a sulfur component in the mixture A method of recovering cyclic polyarylene sulfide and polyarylene sulfide according to claim 1, wherein the mixture obtained by heating and reaction is used. The amount of the organic polar solvent in the mixture (a) is 1.25 liters or more with respect to 1 mol of the sulfur component in the mixture (a). A method for recovering polyarylene sulfide and polyarylene sulfide. In the step of distilling off the organic polar solvent from the mixture (a), the organic polar solvent is distilled off until the amount of the remaining organic polar solvent is 1.0 liter or less relative to 1 mol of the sulfur component in the mixture (b). The cyclic polyarylene sulfide and the method for recovering the polyarylene sulfide according to any one of claims 1 to 4, wherein: The method comprising a step of obtaining a cyclic polyarylene sulfide mixture as a solid from a filtrate component obtained by performing solid-liquid separation (c) in a temperature range in which the polyarylene sulfide is insoluble. 6. The method for recovering cyclic polyarylene sulfide and polyarylene sulfide according to any one of 5 above. The amount of the organic polar solvent in the mixture (b) containing at least polyarylene sulfide, cyclic polyarylene sulfide and the organic polar solvent obtained by distilling off the organic polar solvent is the sulfur component in the mixture (b). The method for recovering cyclic polyarylene sulfide and polyarylene sulfide according to any one of claims 1 to 6, wherein the amount is 0.10 liter or more per mole. The cyclic polyarylene sulfide according to any one of claims 1 to 7, wherein the mixture recovered from the filtrate component obtained by solid-liquid separation (c) contains 50% by weight or more of cyclic polyarylene sulfide. And a method for recovering polyarylene sulfide. The method for recovering a cyclic polyarylene sulfide and a polyarylene sulfide according to any one of claims 1 to 8, wherein the temperature at which the organic polar solvent is distilled off is 140 ° C or higher. The method for recovering a cyclic polyarylene sulfide and a polyarylene sulfide according to any one of claims 1 to 9, wherein the temperature at which the organic polar solvent is distilled off is 180 ° C or higher. The cyclic polyarylene according to any one of claims 1 to 10, further comprising a step of removing the alkali metal halide salt from the mixture containing at least the polyarylene sulfide and the alkali metal halide salt obtained by solid-liquid separation (c). Method for recovering sulfide and polyarylene sulfide.