JP2018076492A - Polyarylne sulfide prepolymer and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a polyarylene sulfide (PAS) prepolymer controlled in composition useful for controlling the molecular weight of the PAS obtained and a method for easily producing the PAS prepolymer in a method for producing PAS by heating a PAS prepolymer containing a cyclic PAS and to provide a method for producing PAS by heating the PAS prepolymer.SOLUTION: There is provided a polyarylene sulfide prepolymer which is obtained by mixing (a) a cyclic polyarylene sulfide containing at least 50 wt.% of a cyclic polyarylene sulfide and having a weight average molecular weight of less than 10000 and (b) a linear polyarylene sulfide having a content of a cyclic polyarylene sulfide of 5 wt.% or less and a weight average molecular weight of 5000 to 20000.SELECTED DRAWING: None

Description

  The present invention relates to a polyarylene sulfide prepolymer, a method for producing the same, and a method for producing polyarylene sulfide using the polyarylene sulfide prepolymer. More particularly, the present invention relates to a polyarylene sulfide prepolymer in which the composition of cyclic polyarylene sulfide and linear polyarylene sulfide is controlled, and a simple and economical production method thereof. Furthermore, the present invention relates to a method for easily producing a polyarylene sulfide having a controlled molecular weight by heating the polyarylene sulfide prepolymer of the present invention or the polyarylene sulfide prepolymer obtained by the production method of the present invention.

  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 has been proposed. This method is widely used as an industrial production method of PAS. However, this production method requires the reaction to be performed under high temperature, high pressure, and strong alkaline conditions, and further requires an expensive high-boiling polar solvent such as N-methyl-2-pyrrolidone. However, it has a problem that it requires a large amount of process cost.

  As another PAS manufacturing method that solves the problems of the PAS manufacturing method as described above, a PAS manufacturing method by heating cyclic PAS is disclosed (Patent Document 1).

  Here, as a known technique related to Patent Document 1, a method is known in which PAS is obtained by heating a mixture with linear PAS by-produced during cyclic PAS synthesis (Non-Patent Document 1). Also, a method of obtaining PAS by heating cyclic PAS in the presence of a sulfidizing agent having a reactive functional group (Patent Document 2), and a ring in the presence of an alkali metal salt of sulfur such as a sodium salt of thiophenol. Methods for heating the PAS to obtain PAS are disclosed (Patent Documents 3 and 4).

  Furthermore, a method of obtaining a PAS excellent in heat resistance and low gas properties by mixing a PAS obtained by a solution polymerization method and a PAS obtained in Patent Document 1 (Patent Document 5), and a PAS obtained in Patent Document 1 A method (Patent Document 6) is disclosed in which a PAS obtained by mixing PAS obtained in Patent Document 2 and having a reactive end and having excellent low gas properties is obtained.

International Publication No. 2007-034800 International Publication No. 2012-057319 JP-A-5-163349 (page 2) JP-A-5-105757 (2nd page) International Publication No. 2013-099234 International Publication No. 2013-161321

Polymer, vol. 37, no. 14, 1996 (pages 3111-3116)

  The PAS obtained by the method described in Patent Document 1 can be expected to obtain a PAS having a high molecular weight and a narrow molecular weight distribution and little weight loss when heated. However, the molecular weight of the PAS obtained depends on the purity of the cyclic PAS to be heated, and the PAS obtained by heating the high-purity cyclic PAS may become excessively high in molecular weight. There has been a demand for a method of reducing and controlling the above.

  Although the method described in Non-Patent Document 1 is an easy polymerization method, since the amount of linear PAS produced as a by-product during the synthesis of cyclic PAS is large, the degree of polymerization of the obtained PAS is low and not suitable for practical use.

  The PAS obtained by the method described in Patent Document 2 has a high molecular weight and a narrow molecular weight distribution, and a PAS with little weight loss when heated can be obtained. In addition, there was a negative relationship between the addition amount of the sulfidizing agent and the molecular weight, but the molecular weight of the sulfidizing agent was small and it was difficult to control due to the volatilization effect during polymerization. Moreover, when the mixing amount of the sulfidizing agent was increased, there was a tendency that the thickening during melt residence increased.

  The PAS obtained by the methods described in Patent Documents 3 and 4 is described as having a narrow molecular weight, and there is a negative relationship between the amount of sulfur alkali metal salt added and the molecular weight. There has been a problem that the amount of the resulting gas component increases.

  PAS obtained by the method described in Patent Document 5 is excellent in heat resistance and low gas properties. Moreover, the effect which controls the molecular weight of PAS obtained by selecting the molecular weight of PAS obtained by the solution polymerization method mixed with PAS obtained by patent document 1 is also expectable. However, since the molecular weight of PAS obtained by the solution polymerization method is high, the effect of reducing the molecular weight is not sufficient, and when the amount of mixing is increased, the amount of gas generation increases, so the amount of mixing is limited and the effect is insufficient. For this reason, a method for controlling by reducing the molecular weight of PAS has been desired.

  PAS obtained by the method described in Patent Document 6 is excellent in low gas properties. Moreover, the effect which controls the molecular weight of PAS obtained by selecting the molecular weight of PAS obtained by patent document 2 mixed with PAS obtained by patent document 1 can also be anticipated. However, since the molecular weight of PAS obtained in Patent Document 2 is still high, the molecular weight reduction effect is not sufficient. In addition, in this method, it is essential to polymerize the polymer to be mixed and then mix at a high temperature, the process is complicated, and a method for easily reducing and controlling the molecular weight of PAS has been desired.

  From the above, in the production method for obtaining PAS by heating a PAS prepolymer containing cyclic PAS, in order to control the molecular weight of the obtained PAS, a PAS prepolymer having a controlled composition and its PAS prepolymer are easily obtained. A production method and a method for producing PAS by heating the PAS prepolymer have been desired.

  In response to the above problems, the present invention heats a PAS prepolymer with a controlled composition of cyclic PAS and linear PAS, a simple production method thereof, and the PAS prepolymer or the PAS prepolymer obtained by the production method of the present invention. Thus, a PAS manufacturing method for obtaining PAS is provided.

That is, the present invention is as follows.
[1] The content of the cyclic polyarylene sulfide (a) containing at least 50% by weight of the cyclic polyarylene sulfide and having a weight average molecular weight of less than 10,000 and the cyclic polyarylene sulfide is 5% by weight or less. And a polyarylene sulfide prepolymer comprising a linear polyarylene sulfide (b) having a weight average molecular weight of from 5,000 to 20,000.
[2] The polyarylene sulfide prepolymer according to [1], wherein the polyarylene sulfide prepolymer contains at least 30% by weight of cyclic polyarylene sulfide and has a weight average molecular weight of less than 10,000.
[3] The weight ratio of cyclic polyarylene sulfide to linear polyarylene sulfide (cyclic polyarylene sulfide / linear polyarylene sulfide) contained in the polyarylene sulfide prepolymer is 0.5 or more and less than 1000 [1] ] Or the polyarylene sulfide prepolymer according to [2].
[4] The polyarylene sulfide prepolymer according to any one of [1] to [3], wherein X represented by the following formula is in the range of 1 to 400.
X = 2a / (Mn / M) × 10000
(Here, the weight fraction of the linear polyarylene sulfide (b) in the polyarylene sulfide prepolymer: a and the number average molecular weight of the linear polyarylene sulfide (b): Mn, the repeating unit molecular weight of PAS: M Value.)
[5] A method for producing a polyarylene sulfide polymer according to any one of [1] to [4] above, wherein the cyclic polyarylene sulfide (a) is produced by the following steps 1, 2 and 3, A method for producing a polyarylene sulfide prepolymer, comprising producing a linear polyarylene sulfide (b) by Step 1 and Step 2, and then mixing the cyclic polyarylene sulfide (a) and the linear polyarylene sulfide (b).
Step 1: Contacting at least a sulfidizing agent and a dihalogenated aromatic compound in an organic polar solvent to obtain a reaction mixture containing at least a cyclic polyarylene sulfide (a) and a linear polyarylene sulfide (b) .
Process 2: The process of solid-liquid separating the reaction mixture obtained through the said process 1, and obtaining linear polyarylene sulfide (b) as solid content.
Step 3: A step of obtaining cyclic polyarylene sulfide (a) as a solid content from an organic polar solvent containing at least cyclic polyarylene sulfide obtained by solid-liquid separation of the reaction mixture obtained through Step 1 above.
[6] When the weight of the cyclic polyarylene sulfide (a) is 100, the weight ratio of the linear polyarylene sulfide (b) to the cyclic polyarylene sulfide (a) is in the range of 0.1 to 200. The method for producing a polyarylene sulfide prepolymer according to claim 5, wherein the polyarylene sulfide (b) is mixed.
[7] The process for producing a polyarylene sulfide prepolymer according to [5] or [6], wherein the step 1 is performed in an organic polar solvent of 1.25 to 50 liters per 1 mol of the sulfur component.
[8] The polyarylene according to any one of [5] to [7], wherein the linear polyarylene sulfide (b) is produced by a step of washing the obtained linear polyarylene sulfide after the step 2 with a solvent. A method for producing a sulfide prepolymer.
[9] A method for producing polyarylene sulfide, wherein the polyarylene sulfide prepolymer according to any one of [1] to [4] is heated to be converted to a high degree of polymerization having a weight average molecular weight of 10,000 or more.
[10] A polyarylene sulfide prepolymer is obtained by the method for producing a polyarylene sulfide prepolymer according to any one of [5] to [8], and then the polyarylene sulfide prepolymer is heated to have a weight average molecular weight of 10,000. The manufacturing method of the polyarylene sulfide converted into the above high degree-of-polymerization bodies.
[11] The method for producing a polyarylene sulfide as described in [9] or [10] above, wherein the obtained polyarylene sulfide satisfies the following (1) to (3).
(1) The weight average molecular weight is 10,000 or more.
(2) The degree of dispersion represented by weight average molecular weight / number average molecular weight is 2.5 or less.
(3) The weight reduction rate ΔWr when heated satisfies the following formula.
ΔWr = (W1-W2) /W1×100≦0.18 (%)
(Here, ΔWr is the weight loss rate (%), and when the thermogravimetric analysis was performed from 50 ° C. to 330 ° C. at a heating rate of 20 ° C./min in a normal pressure non-oxidizing atmosphere, when 100 ° C. was reached. (It is a value obtained from the sample weight (W2) when reaching 330 ° C. based on the sample weight (W1))

  According to the present invention, a composition-controlled PAS prepolymer useful for controlling the molecular weight of the resulting PAS and a PAS prepolymer useful for controlling the molecular weight of the resulting PAS in a production method for heating a PAS prepolymer containing cyclic PAS to obtain PAS. A production method for easily obtaining a polymer and a method for producing a PAS by heating the PAS prepolymer can be provided.

  Embodiments of the present invention will be described below.

<Cyclic polyarylene sulfide>
In the present invention, cyclic PAS is a cyclic compound having a repeating unit of the formula-(Ar-S)-as a main structural unit, and preferably contains the following general formula (A) containing 80 mol% or more of the repeating unit. It is a compound such as Ar includes units represented by the above formulas (B) to (L), among which the formula (B) is particularly preferable.

  As long as these repeating units are the main structural units, they can contain a small amount of branch units or crosslinking units represented by the following formulas (M) to (O). 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 the cyclic PAS, the repeating units such as the above formulas (B) to (L) may be included at random, may be included in blocks, or may be any mixture thereof. 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 PASs include p-phenylene sulfide units as the main structural unit.

Is a cyclic polyphenylene sulfide (hereinafter sometimes abbreviated as cyclic PPS).

  Although there is no restriction | limiting in particular in the repeating number m in the said (A) type | formula of cyclic PAS, 2-50 are preferable, 2-25 are more preferable, and 3-20 can be illustrated as a still more preferable range. As will be described later, the conversion of the PAS prepolymer to a high degree of polymerization is preferably performed at a temperature higher than that at which the cyclic PAS melts, but as m increases, the melting temperature of the cyclic PAS tends to increase. From the viewpoint that the conversion of the PAS prepolymer to a high degree of polymerization can be performed at a lower temperature, it is advantageous to set m in the above range.

  The cyclic PAS may be either a single compound having a single repeat number or a mixture of cyclic PASs having different repeat numbers, but a mixture of cyclic PAS having different repeat numbers is a single repeat. Use of a mixture of cyclic PAS having a different number of repetitions tends to be lower than that of a single compound having a number, and is preferable because the temperature during conversion to a high degree of polymerization described below can be further lowered.

<Cyclic polyarylene sulfide (a)>
The content of the cyclic PAS contained in the cyclic PAS (a) of the present invention is 50% or more by weight, preferably 60% or more, more preferably 75% or more, still more preferably 80% or more. . Although there is no restriction | limiting in particular in the upper limit of cyclic PAS content, Preferably it is 98% or less, More preferably, 95% or less can be illustrated. Usually, the higher the weight ratio of cyclic PAS in the PAS prepolymer described later, the higher the degree of polymerization of PAS obtained after heating. Therefore, the weight ratio of cyclic PAS in cyclic PAS (a) is within the above range. It is preferable to make the weight ratio of the cyclic PAS in the PAS prepolymer of the present invention wide. In addition, when the weight ratio of the cyclic PAS in the cyclic PAS (a) exceeds the upper limit described above, the melting solution temperature of the cyclic PAS (a) tends to increase, so that the ring in the cyclic PAS (a) It is preferable to set the weight ratio of the formula PAS in the above range because the temperature when the PAS prepolymer described later is converted into a high degree of polymerization can be further lowered.

  In the present invention, the content of the cyclic PAS contained in the cyclic PAS (a) is, when the solvent is contained in the cyclic PAS (a), a weight fraction obtained by subtracting the content as 100. It means rate.

  The components other than cyclic PAS (a) in cyclic PAS (a) are particularly preferably linear PAS oligomers. Here, the linear PAS oligomer is a homo-oligomer or a co-oligomer having a repeating unit of the formula-(Ar-S)-as a main constituent unit, preferably containing 80 mol% or more of the repeating unit. Ar includes units represented by the above-described formulas (B) to (L), among which the formula (B) is particularly preferable. The linear PAS oligomer can contain a small amount of branch units or crosslinking units represented by the above formulas (M) to (O) as long as these repeating units are the main constituent units. 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. The linear PAS oligomer 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 oligomers, polyphenylene sulfide sulfone oligomers, polyphenylene sulfide ketone oligomers, random copolymers, block copolymers, and mixtures thereof. Particularly preferred linear PAS oligomers include linear polyphenylene sulfide oligomers containing 80 mol% or more, particularly 90 mol% or more of p-phenylene sulfide units as the main structural unit of the polymer.

  The weight average molecular weight of the linear PAS oligomer contained in the cyclic PAS (a) is preferably from 300 to 5,000, more preferably from 300 to 3,000, still more preferably from 300 to 2,000. Since the linear PAS oligomer contained in the cyclic PAS (a) of the present invention is obtained through Step 2 described later, it usually has a weight average molecular weight of 300 to 5,000.

  The upper limit of the molecular weight of the cyclic PAS (a) used for the production of the PAS of the present invention is less than 10,000 in terms of weight average molecular weight, preferably 5,000 or less, and more preferably 3,000 or less. On the other hand, the lower limit is preferably 300 or more, preferably 400 or more, and more preferably 500 or more in terms of weight average molecular weight.

<Linear polyarylene sulfide>
The linear PAS in the present invention is a repeating unit of the formula-(Ar-S)-composed of an arylene group (hereinafter sometimes abbreviated as Ar) and a sulfide, and is preferably the repeating unit. A homopolymer or copolymer containing 80 mol% or more. Ar includes units represented by the above formulas (B) to (L), among which the formula (B) is particularly preferable.

  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 above formulas (M) to (O). 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 PAS in the present invention may be any of a random copolymer containing the above repeating unit, a block copolymer and a mixture thereof.

  Typical examples thereof include polyphenylene sulfide, polyphenylene sulfide sulfone, polyphenylene sulfide ketone, random copolymers thereof, block copolymers, and mixtures thereof. Particularly preferable linear PASs include polyphenylene sulfide (hereinafter sometimes abbreviated as PPS) containing 80 mol% or more, particularly 90 mol% or more of p-arylene sulfide units as the main structural unit of the polymer. Examples include sulfone and polyphenylene sulfide ketone.

<Linear polyarylene sulfide (b)>
Moreover, the molecular weight of the linear PAS (b) of the present invention is 5000 to 20000 in terms of weight average molecular weight, preferably 5000 to 18000, and more preferably 5000 to 16000. A linear PAS (b) having a weight average molecular weight in the above range is highly effective in reducing the molecular weight when linear PAS (b) is mixed with a PAS prepolymer. In addition, since the volatilization is small even under a high temperature environment in the production of PAS described later and the thermal stability is high, the target PAS tends to be obtained with good reproducibility. Furthermore, such linear PAS (b) is likely to exist as a solid in an organic polar solvent under the conditions for performing the separation operation of cyclic PAS (a) and linear PAS (b) described later. The separability from cyclic PAS (a) tends to be remarkably improved, and it can be said that it is particularly suitable in the present invention.

  As described above, since the separation property from the cyclic PAS (a) is remarkably high, the cyclic PAS content contained in the linear PAS (b) of the present invention is 5% or less by weight, 3% The following is preferable, and 2% or less is more preferable. In the linear PAS (b) in which the cyclic PAS content is in the above range, the gas generation amount of PAS obtained by the production of PAS described later tends to be small. The reason for this is not clear at this time, but part of the gas components generated during the heating of the PAS is due to the impurity structure. By reducing the cyclic PAS contained in the linear PAS (b), the cyclic PAS is reduced. It is presumed that the low molecular weight oligomers exhibiting a dissolution behavior similar to those of the above-mentioned are simultaneously reduced, so that the PAS prepolymer described later is highly purified, and the PAS obtained from the PAS prepolymer is also highly purified.

  In the present invention, when the linear PAS (b) contains a solvent, the content of the cyclic PAS (a) contained in the linear PAS (b) is calculated as 100 by subtracting the content of the solvent. It shall mean the weight fraction obtained.

<Polyarylene sulfide prepolymer>
The PAS prepolymer of the present invention comprises a mixture comprising at least cyclic PAS (a) and linear PAS (b). The content of linear PAS contained in the PAS prepolymer is less than the cyclic PAS contained in the PAS prepolymer. That is, the weight ratio of cyclic PAS to linear PAS in the PAS prepolymer (cyclic PAS / linear PAS) is preferably 0.5 or more and less than 1000, preferably 1.5 or more and less than 1000, and more preferably 2 or more and 100 or less. Preferably, it is 3 or more and 30 or less, more preferably 4 or more and 20 or less. When the content of linear PAS in the PAS prepolymer increases and the weight ratio falls below the lower limit, the melt solution temperature of the PAS prepolymer tends to increase. Therefore, the cyclic PAS and linear PAS in the PAS prepolymer tend to increase. It is preferable to set the weight ratio in the above range because the process temperature when the PAS prepolymer is converted into a high polymerization degree can be further lowered.

  By controlling the mixing ratio of cyclic PAS (a) and linear PAS (b) in the PAS prepolymer of the present invention, the molecular weight of PAS obtained can be controlled by the PAS production method described later. That is, by increasing the content of linear PAS (b) in the PAS prepolymer and reducing the weight ratio of the above-mentioned cyclic PAS and linear PAS, the weight average molecular weight of the resulting PAS tends to decrease. . On the other hand, the weight average molecular weight of PAS obtained by reducing the content of linear PAS (b) and increasing the weight ratio of the above-mentioned cyclic PAS and linear PAS tends to increase.

Further, in the PAS prepolymer of the present invention, X represented by the following formula is preferably 1 or more and 400 or less, preferably 1 or more and 200 or less, more preferably 5 or more and 170 or less, further preferably 15 or more and 130 or less, and 20 or more. 110 or less is even more preferable.
X = 2a / (Mn / M) × 10000 (I)

  Here, X is an approximate value of the terminal amount derived from linear PAS (b) introduced into the PAS obtained by the production method of the present invention, and the weight fraction of linear PAS (b) in the PAS prepolymer: The number average molecular weight of a and linear PAS (b): Mn, and the repeating unit molecular weight of PAS: M.

  The PAS heating gas amount obtained when X exceeds the upper limit because the weight fraction in the PAS prepolymer of linear PAS (b) is large and / or the number average molecular weight of linear PAS (b) is small. It tends to increase. For example, in the case of PAS, the normal main chain structure is an arylene sulfide unit, whereas the halogeno group terminal and the thiol terminal, which are general terminal structures of PAS, have different electronic states from the main chain structure. It is unstable compared to the chain structure. Therefore, it is presumed that an unstable terminal structure becomes the starting point of thermal decomposition when heated, and it is considered that the amount of weight loss during heating increases as the terminal amount increases.

  When the weight fraction of the linear PAS (b) in the PAS prepolymer is small and / or the number average molecular weight of the linear PAS (b) is large and therefore X is below the lower limit, the linear PAS (b) Compared with the case where they are not mixed, the effect of lowering the degree of polymerization of PAS tends to be poor.

  In addition to the weight ratio of cyclic PAS and linear PAS in the PAS prepolymer described above, by controlling the value represented by X in the PAS prepolymer, the PAS obtained by the PAS production method described later can be used. The molecular weight can be controlled with higher accuracy. That is, when the content of linear PAS (b) in the PAS prepolymer is increased and / or the value represented by X is increased using a linear PAS (b) having a small number average molecular weight, it is obtained. The weight average molecular weight of the PAS obtained tends to decrease. On the other hand, when the content of linear PAS (b) in the PAS prepolymer is reduced and / or the value represented by the above X is reduced using a linear PAS (b) having a large number average molecular weight, it is obtained. The weight average molecular weight of the resulting PAS tends to increase. The content of cyclic PAS contained in the PAS prepolymer used in the present invention is preferably 30% or more, preferably 50% or more, more preferably 60% or more, and still more preferably 75% or more by weight fraction. Although there is no restriction | limiting in particular in the upper limit of cyclic PAS content, Preferably it is 98% or less, More preferably, 95% or less can be illustrated. Usually, the higher the weight ratio of cyclic PAS in the PAS prepolymer, the higher the degree of polymerization of PAS obtained after heating. Therefore, setting the weight ratio of cyclic PAS in the PAS prepolymer in the above range is as follows. In the process for producing PAS of the present invention, the range of the degree of polymerization of PAS obtained is preferable. In addition, when the weight ratio of cyclic PAS in the PAS prepolymer is below the lower limit value described above, the melt solution temperature of the PAS prepolymer tends to increase. Therefore, the weight ratio of cyclic PAS in the PAS prepolymer is within the above range. It is preferable to do so because the temperature at which the PAS prepolymer is converted into a high degree of polymerization can be lowered.

  In the present invention, the content of cyclic PAS contained in the PAS prepolymer means a weight fraction obtained by subtracting the content from 100 when the solvent is contained in the PAS prepolymer. To do.

  The upper limit of the molecular weight of the PAS prepolymer that satisfies the above conditions is preferably less than 10,000 in terms of weight average molecular weight, more preferably 8,000 or less, and even more preferably 5,000 or less. On the other hand, the lower limit is preferably 300 or more, preferably 400 or more, and more preferably 500 or more in terms of weight average molecular weight.

<Sulphiding agent>
The sulfidizing agent used in the present invention is not particularly limited as long as it can introduce a sulfide bond into the dihalogenated aromatic compound described below and / or can generate an arylene thiolate by acting on the arylene sulfide bond. Examples include sulfides, alkali metal hydrosulfides, and hydrogen sulfide. Among them, alkali metal hydrosulfides are particularly preferable.

  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 preferred to use such forms of alkali metal sulfides.

  Specific examples of the alkali metal hydrosulfide include, for example, lithium hydrosulfide, sodium hydrosulfide, potassium hydrosulfide, lithium hydrosulfide, rubidium hydrosulfide, cesium hydrosulfide, and mixtures of two or more thereof. Lithium hydrosulfide and / or sodium hydrosulfide are preferable, and sodium hydrosulfide is more preferably used.

  In addition, an alkali metal sulfide prepared in situ in a reaction system from an alkali metal hydrosulfide and an alkali metal hydroxide can also be used. Alternatively, an alkali metal sulfide prepared by previously contacting an alkali metal hydrosulfide and an alkali metal hydroxide can 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 situ 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 the remaining amount obtained by subtracting the amount of loss from the actual charge amount when a partial loss of the sulfidizing agent occurs before the reaction with the dihalogenated aromatic compound due to dehydration operation or the like. It shall mean quantity.

  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 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 sulfiding agent, it is particularly preferable to use an alkali metal hydroxide at the same time, but the amount used is 0.95 to 1. 50 moles, preferably 1.00 to 1.25 moles, more preferably 1.005 to 1.200 moles, more preferably 1.005 to 1.100 moles, and even more preferably 1.005 to 1.05 moles The most preferable range is 1.005 to 1.04 mol.

  Further, when hydrogen sulfide and / or alkali metal sulfide is used as a sulfidizing agent, an alkali metal hydroxide can be used at the same time. In this case, the amount of alkali metal hydroxide used in the present invention is not the actual amount used, but is expressed in terms of convenience, based on alkali metal hydrosulfide, which is a particularly preferred sulfiding agent in the present invention.

  That is, when hydrogen sulfide is used as a sulfidizing agent, the amount of alkali metal hydroxide used is, in principle, from 1 mole of hydrogen sulfide and 1 mole of alkali metal hydroxide in situ in the reaction system. Since a mole is formed, it is expressed by subtracting 1 mole from the alkali metal hydroxide actually used for 1 mole of hydrogen sulfide. Therefore, the preferable amount of the alkali metal hydroxide with respect to 1 mol of hydrogen sulfide in the above conversion in the present invention is 0.95 to 1.50 mol, more preferably 1.00 to 1.25 mol, still more preferably 1 0.005 to 1.200 moles, still more preferably 1.005 to 1.100 moles, and even more preferably 1.005 to 1.05 moles, most preferably 1.005 to 1.04 moles. The actual range of the preferred amount of alkali metal hydroxide per mole of these hydrogen sulfides is 1.95 to 2.50 moles, more preferably 2.00 to 2.25 moles, even more preferably 2.005 to 2.200 mol, still more preferably 2.005 to 2.100 mol, even more preferably 2.005 to 2.05 mol, most preferably 2.005 to 2.04 mol.

  The amount of alkali metal hydroxide used when alkali metal sulfide is used as the sulfiding agent is, in principle, 1 mol of alkali metal sulfide from 1 mol of alkali metal hydrosulfide and 1 mol of alkali metal hydroxide. In order to produce | generate, it represents with the quantity which added 1 mol to the alkali metal hydroxide actually used with respect to 1 mol of alkali metal sulfides. Therefore, the preferable amount of the alkali metal hydroxide in the above conversion in the present invention is 1.00 to 1.50 mol, more preferably 1.00 to 1.25 mol, more preferably 1.005 to 1. 200 mol, more preferably 1.005 to 1.100 mol, still more preferably 1.005 to 1.05 mol, and most preferably 1.005 to 1.04 mol. The preferred practical range of alkali metal hydroxides per mole of these alkali metal sulfides is 0.00 to 0.50 moles, more preferably 0.00 to 0.25 moles, more preferably 0.00. 005 to 0.200 mol, more preferably 0.005 to 0.100 mol, still more preferably 0.005 to 0.05 mol, and most preferably 0.005 to 0.04 mol.

<Dihalogenated aromatic compound>
The dihalogenated aromatic compound used in the present invention is an aromatic compound composed of an arylene group which is a divalent group of an aromatic ring and two halogeno groups, and 1 mol of a dihalogenated aromatic compound is 1 mol of an arylene unit. Consists of 2 moles of halogeno groups. For example, as a compound comprising a phenylene group which is a divalent group of a benzene ring as an arylene group and two halogeno groups, p-dichlorobenzene, o-dichlorobenzene, m-dichlorobenzene, p-dibromobenzene, o-dibromobenzene, Dihalogenated benzenes such as m-dibromobenzene, 1-bromo-4-chlorobenzene, 1-bromo-3-chlorobenzene, and 1-methoxy-2,5-dichlorobenzene, 1-methyl-2,5-dichlorobenzene, 1 , 4-dimethyl-2,5-dichlorobenzene, 1,3-dimethyl-2,5-dichlorobenzene, 3,5-dichlorobenzoic acid and other dihalogenated aromatic compounds containing a substituent other than halogen. be able to. 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 a combination of two or more different dihalogenated aromatic compounds in order to obtain a cyclic PAS copolymer.

<Organic polar solvent>
In the embodiment of the present invention, an organic polar solvent is used when a reaction between a sulfidizing agent and a dihalogenated aromatic compound is performed or when a solid-liquid separation of a reaction product obtained by the reaction is performed. Is preferably an organic amide solvent. Specific examples include N-alkylpyrrolidones such as N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-cyclohexyl-2-pyrrolidone, N-methyl-ε-caprolactam, ε -Aprotic organic solvents represented by caprolactams such as caprolactam, 1,3-dimethyl-2-imidazolidinone, N, N-dimethylacetamide, N, N-dimethylformamide, hexamethylphosphoric triamide, and the like, and A mixture or the like is preferably used because of its high reaction stability. Among these, N-methyl-2-pyrrolidone and 1,3-dimethyl-2-imidazolidinone are preferably used.

  In the embodiment of the present invention, the amount of the organic polar solvent used in the reaction of at least the sulfidizing agent, the dihalogenated aromatic compound and the organic polar solvent is 1 with respect to 1 mol of the sulfur component in the reaction mixture. 25 liters or more and 50 liters or less are preferable. The more preferable lower limit of the amount of the organic polar solvent used is 1.5 liters or more, and more preferably 2 liters or more. On the other hand, as a more preferable upper limit, 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.

  When the amount of the nitrogen-containing organic polar solvent used is less than 1.25 liter, the production rate of cyclic PAS produced by the reaction between the sulfidizing agent and the dihalogenated aromatic compound tends to be extremely low. Further, it is not preferable because a linear PAS having a high molecular weight tends to be generated, and the effect of reducing the molecular weight when the linear PAS (b) is mixed becomes low. Further, it is presumed that the generation probability of impurity oligomers and the generation probability of impurity-type ends due to side reactions are increased, and the gas generation amount of PAS finally obtained tends to increase.

  Here, the production rate of cyclic PAS refers to the production amount of cyclic PAS when it is assumed that all of the sulfidizing agent used in the production of the reaction mixture described in detail later is converted to cyclic PAS. It is the ratio of the amount of cyclic PAS actually produced in the production of the reaction mixture. If it is 100%, it means that all of the sulfidizing agent used has been converted to cyclic PAS. The production rate of linear PAS is actually generated by the production of the reaction mixture with respect to the production amount of linear PAS when it is assumed that all of the sulfidizing agent used for the preparation of the reaction mixture is converted to linear PAS. It is the ratio of the linear PAS amount.

  Here, the higher the production rate of cyclic PAS, the more preferable is the viewpoint that the sulfiding agent used is more efficiently converted to cyclic PAS. However, when the amount of the organic polar solvent used is extremely increased in the production of the reaction mixture in order to achieve a very high production rate, the amount of cyclic PAS produced per unit volume of the reaction vessel tends to decrease. Also, the time required for the reaction tends to increase. Furthermore, when performing an operation of isolating and recovering cyclic PAS, if the amount of the organic polar solvent used is too large, the amount of cyclic PAS per unit amount of the reactant becomes a very small amount, which makes the recovery operation difficult. It is preferable to make it the usage-amount range of an organic polar solvent mentioned above from a viewpoint of making the production | generation rate and productivity of cyclic PAS compatible.

  In addition, the amount of the solvent used in the production of a general cyclic compound is very large in many cases, and the cyclic compound is often not efficiently obtained within the preferable amount range of the present invention. In the present invention, cyclic PAS can be efficiently obtained even under conditions where the amount of solvent used is relatively small compared to the case of production of a general cyclic compound, that is, when the amount is not more than the above-mentioned upper limit value of the preferred amount of solvent used. The reason for this is not clear at the present time, but in the method of the present invention, the reaction is carried out above the reflux temperature of the reaction mixture, so that the reaction efficiency is very high and the raw material consumption rate is suitable for the production of the cyclic compound. I guess it is. Here, the usage amount of the organic polar solvent in the reaction mixture is an amount obtained by subtracting the organic polar solvent removed from the reaction system from the organic polar solvent introduced into the reaction system.

<Method for producing PAS prepolymer>
In the method for producing a PAS prepolymer of the present invention, cyclic PAS (a) obtained through Step 1, Step 2 and Step 3 described later and linear PAS (b) obtained through Step 1 and Step 2 were produced. Later, the obtained cyclic PAS (a) and linear PAS (b) are mixed to produce a PAS prepolymer.

<Step 1: Production of reaction mixture containing cyclic polyarylene sulfide (a) and linear polyarylene sulfide (b)>
In the present invention, at least the sulfidizing agent and the dihalogenated aromatic compound are contacted in an organic polar solvent to obtain a reaction mixture containing at least cyclic PAS (a) and linear PAS (b). As the method of step 1, the above-mentioned essential components may be used as raw materials, but preferred methods include known methods disclosed in JP2009-30012A and JP2009-227952A. In these known methods, in order to obtain cyclic PAS efficiently, a reaction mixture is produced by bringing a sulfidizing agent and a dihalogenated aromatic compound into contact with each other in an organic polar solvent. It is characterized by using 1.25 liters or more of an organic polar solvent per mole and heating the raw material beyond the reflux temperature at normal pressure.

  More preferably, the reaction mixture can also be obtained by the method disclosed in International Publication No. 2013/061561. In the method, a pre-stage step of heating a raw material having an arylene unit of 0.80 mol or more and 1.04 mol per mol of a sulfur component to cause reaction consumption of 50% or more of the sulfidizing agent in the raw material; Subsequent to the previous step, the dihalogenated aromatic compound is added and further heated and reacted so that the arylene unit per mole of the sulfur component in the raw material is 1.05 mol or more and 1.50 mol or less. Perform the steps to obtain a reaction mixture. This method is preferable because cyclic PAS (a) with higher purity can be obtained by additionally performing the recovery operation in Step 3 described later.

  Further, when obtaining a reaction mixture by the method disclosed in the above-mentioned International Publication No. 2013/061561, the reaction may be nearly completed in a subsequent step performed by adding a dihalogenated aromatic compound after the above-mentioned previous step. Further preferred. Here, the completion of the reaction means that most of the sulfidizing agent charged in the subsequent step, that is, preferably 90% or more, more preferably 95% or more is consumed, and the reaction is further performed to 99% or more. Consumption of raw material sulfidizing agent and dihalogenated aromatic processed product. The time required for completion of the reaction depends on the type of raw material or the reaction temperature, and thus cannot be defined unconditionally. However, a preferable lower limit of the reaction time is 0.1 hour or longer, and more preferably 0.25 hour or longer. On the other hand, as an upper limit of preferable reaction time, 20 hours or less can be illustrated, Preferably it is 10 hours or less, More preferably, 5 hours or less is employable. By bringing the reaction close to completion, cyclic PAS can be obtained in good yield, and high-purity cyclic PAS (a) can be obtained by additionally performing the recovery operation in Step 3 described later.

<Step 2: Production of linear polyarylene sulfide (b)>
In the embodiment of the present invention, as the step 3 subsequent to the step 1, the reaction product obtained in the step 1 is subjected to solid-liquid separation, so that the solid linear PAS (b) mainly containing the linear PAS, A step of obtaining a filtrate mainly containing cyclic PAS and an organic polar solvent is carried out.

  As the method of Step 2, it is sufficient that the reaction product obtained in Step 1 can be subjected to solid-liquid separation. However, a preferable method is a known method disclosed in Japanese Patent Application Laid-Open No. 2009-149863. In these known methods, in order to obtain cyclic PAS, a reaction mixture obtained by bringing a sulfidizing agent and a dihalogenated aromatic compound into contact with each other in an organic polar solvent is subjected to solid-liquid separation, which is below the boiling point of the organic polar solvent. It is characterized by solid-liquid separation at a temperature of In this method, the linear PAS (b) tends to exist as a solid in an organic polar solvent under the conditions for performing the separation operation, so that the separability from the cyclic PAS (a) tends to be remarkably improved. ,preferable.

  In addition, prior to subjecting the reaction product to a solid-liquid separation operation, an additional operation of distilling off part of the organic polar solvent contained in the reaction mixture to reduce the amount of the organic polar solvent in the reaction mixture is performed. Is also possible. As a result, the reaction mixture used for the solid-liquid separation operation decreases, so that the time required for the solid-liquid separation operation tends to be shortened.

  As a method for distilling off the organic polar solvent, any method can be used as long as the organic polar solvent is separated from the reaction mixture and the amount of the organic polar solvent contained in the reaction mixture can be reduced. Examples thereof include a method of distilling the organic polar solvent under or under pressure, a method of removing the solvent by flash transfer, and the method of distilling the organic polar solvent under reduced pressure or under pressure is particularly 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 reaction product, and therefore cannot be uniquely determined, but is preferably 180 to 300 ° C., preferably 200 to 280. ° C is more preferable, and a range of 200 to 250 ° C can be exemplified as a more preferable range.

  According to the solid-liquid separation here, most of the cyclic PAS contained in the reaction mixture can be separated as a filtrate component, preferably 80% or more, more preferably 90% or more, and still more preferably 95% or more. It can be recovered as a filtrate component. In addition, when a part of the cyclic PAS remains in the linear PAS (b) separated as a solid content by solid-liquid separation, by washing with a fresh organic polar solvent with respect to the solid content, It is also possible to reduce the residual amount of cyclic PAS in the solid content. The solvent used here may be any solvent that can dissolve cyclic PAS, and is preferably the same solvent as the organic polar solvent used in Step 1 described above.

  Further, prior to subjecting the linear PAS (b) to the mixing operation described later, when the liquid component (mother liquid) contained in the linear PAS (b) is included, various solid linear PAS (b) are used. It is possible to reduce the mother liquor by washing with a solvent. Here, various solvents used for washing are preferably those having low solubility of linear PAS, such as water, alcohols represented by methanol, ethanol, propanol, isopropanol, butanol and hexanol, and ketones represented by acetone. , Acetates represented by ethyl acetate, butyl acetate, and the like, and mixed solvents of these solvents and the organic polar solvent used in Step 1, and water, methanol and acetone from the viewpoint of liquid availability and economy, Moreover, the liquid mixture of these solvents and the organic polar solvent used at the process 1 is preferable, and the liquid mixture of water and the organic polar solvent used at the process 1 is especially preferable.

<Step 3: Production of cyclic polyarylene sulfide (a)>
Next, in this recovery method, cyclic PAS (a) is recovered as a solid content from an organic polar solvent containing at least cyclic PAS obtained by solid-liquid separation of the reaction product obtained in step 2.

  As a method for recovering cyclic PAS (a), it is sufficient if cyclic PAS (a) can be recovered as a solid content from an organic polar solvent containing at least cyclic PAS obtained by solid-liquid separation in step 2. As a preferable method, a known method disclosed in JP 2012-229320 A can be mentioned. In these known methods, a cyclic PAS is recovered as a solid by adding a solution different from the organic polar solvent to an organic polar solvent containing at least cyclic PAS obtained by solid-liquid separation of the reaction mixture. This method is preferable because cyclic PAS (a) having a high purity can be recovered in a simple method and in a short time.

  When the recovered cyclic PAS (a) contains a liquid component (mother liquor), the mother liquor can be reduced by washing the solid cyclic PAS (a) with various solvents. Here, as the various solvents used for washing cyclic PAS, solvents having low solubility of cyclic PAS (a) are desirable, such as water, alcohols typified by methanol, ethanol, propanol, isopropanol, butanol, hexanol, and acetone. Examples include ketones represented by representatives, acetic esters represented by ethyl acetate, butyl acetate, and the like, and mixed solvents of these solvents and the organic polar solvent used in Step 1, and water from the viewpoint of liquid availability and economy. Methanol and acetone, and a mixed solution of these solvents and the organic polar solvent used in Step 1, are particularly preferable water and a mixed solution of water and the organic polar solvent used in Step 1. By additionally performing cleaning using such a solvent, not only can the amount of the mother liquor contained in the solid cyclic PAS (a) be reduced, but it is soluble in the solvent contained in the cyclic PAS (a). There is also an effect that impurities can be reduced. Examples of this washing method include a method of solid-liquid separation by adding a solvent on a separation filter in which a solid cake is laminated, and a method of solid-liquid separation again after slurrying by adding a solvent to the solid cake and stirring. it can. In addition, wet cyclic PAS (a) containing a liquid component containing the above-mentioned mother liquor or containing a solvent component by a washing operation, for example, is subjected to a general drying process to remove the liquid component and dry. It is also possible to obtain the cyclic PAS (a) in the state.

  In addition, it is preferable to perform the atmosphere at the time of performing collection | recovery operation of cyclic PAS (a) in a non-oxidizing atmosphere. As a result, not only the occurrence of undesirable side reactions such as crosslinking reaction, decomposition reaction, oxidation reaction, etc. of cyclic PAS (a) when cyclic PAS (a) is recovered, but also organic polar solvent used for the recovery operation It tends to suppress undesirable side reactions such as oxidative degradation. The non-oxidizing atmosphere is an atmosphere in which the oxygen concentration in the gas phase in contact with various components subjected to the recovery operation is 5% by volume or less, preferably 2% by volume or less, and more preferably contains substantially no oxygen, that is, nitrogen or helium. And an inert gas atmosphere such as argon. Among them, a nitrogen atmosphere is particularly preferable from the viewpoint of economy and ease of handling.

<Method for producing polyarylene sulfide prepolymer>
The PAS prepolymer of the present invention is obtained by mixing cyclic PAS (a) and linear PAS (b). The mixing ratio of the cyclic PAS (a) and the linear PAS (b) is preferably 0.1 to 200 when the cyclic PAS (a) is 100, and the weight ratio of the linear PAS (b) is preferably from 0.1 to 200. 1 or more and 70 or less are preferable, 1 or more and 50 or less are more preferable, 3 or more and 35 or less are still more preferable, and 5 or more and 25 or less are even more preferable. When the mixing amount of the linear PAS (b) is large and the mixing ratio of the linear PAS (b) exceeds the above upper limit, the weight ratio of the PAS prepolymer obtained by mixing (cyclic PAS / linear PAS) and X The value represented tends to deviate from the preferred range in the present invention. On the other hand, when the mixing amount of the linear PAS (b) is small and the mixing ratio of the linear PAS (b) is lower than the lower limit, the weight ratio of the PAS prepolymer (cyclic PAS / linear PAS) obtained by mixing and The value represented by X tends to deviate from the preferred range in the present invention.

  In the present invention, cyclic PAS (a) and linear PAS (b) may be mixed, but it is preferable to mix so that the entire composition is as uniform as possible. Examples of the method of uniformly dispersing include a method of mixing mechanically, a method of mixing using a solvent, and a method of melting and mixing a PAS prepolymer.

  Specific examples of the mechanical mixing method include a pulverizer, a stirrer, a mixer, a shaker, and a method using a mortar. When cyclic PAS (a) and linear PAS (b) are mixed as a solid, more uniform mixing is possible, so the average particle size of cyclic PAS (a) and linear PAS (b) is 1 mm or less. Preferably, it is 500 μm or less, and more preferably 200 μm or less.

  As a method of mixing using a solvent, specifically, cyclic PAS (a) is dissolved or dispersed in an appropriate solvent, and after adding a predetermined amount of linear PAS (b) in a solid or solution state, A method for removing the solvent can be exemplified. The solvent for dissolving or dispersing cyclic PAS (a) is not particularly limited as long as it does not have an action of modifying cyclic PAS. For example, N-methyl-2-pyrrolidone, dimethylformamide, dimethylacetamide Nitrogen-containing polar solvents such as dimethyl sulfoxide, dimethyl sulfone, sulfoxide and sulfone solvents, acetone, methyl ethyl ketone, diethyl ketone, acetophenone and other ketone solvents, dimethyl ether, dipropyl ether, tetrahydrofuran and other ether solvents, chloroform, chloride Halogen solvents such as methylene, trichlorethylene, ethylene dichloride, dichloroethane, tetrachloroethane, chlorobenzene, methanol, ethanol, propanol, butanol, pentanol, ethylene glycol Le, propylene glycol, phenol, cresol, alcohol phenol based solvents such as polyethylene glycol, benzene, toluene, and aromatic hydrocarbon solvents and water, such as xylene. It is also possible to use an inorganic compound such as carbon dioxide, nitrogen, or water as a solvent in a supercritical fluid state. These solvents can be used as one kind or a mixture of two or more kinds. The solvent for dissolving or dispersing the linear PAS (b) is not particularly limited, and examples thereof include those exemplified as the solvent for dissolving or dispersing the cyclic PAS (a).

  The method for adding the linear PAS (b) solution is not particularly limited. For example, the solution is added dropwise to the cyclic PAS (a) or the cyclic PAS (a) solution containing the dispersion or solvent of the cyclic PAS (a). Or spraying. When added using a solvent, remove the solvent while mixing with a tumble or dryer equipped with a stirring blade, or use a normal mixer such as a Henschel mixer or ribbon blender at room temperature or under heating. And then the solvent is removed by evaporation or the like. In addition, a PAS prepolymer containing a solvent may be used in the PAS production process described later, and a method of removing the solvent in a temperature raising process during production may be used.

  As a method of melting and mixing the PAS prepolymer, after the cyclic PAS (a) and the linear PAS (b) are mixed, the PAS prepolymer is melted by heating, after the cyclic PAS (a) is previously melted An example is a method in which a predetermined amount of linear PAS (b) is added in a state of being dispersed in a solid or a solvent. When the linear PAS (b) is added after the cyclic PAS (a) is melted in advance, the linear PAS (b) may be added at once or may be added in a plurality of times. In addition, the melt mixing of the PAS prepolymer can be performed inside or outside a polymerization reaction apparatus, a mold for producing a molded article, an extruder, a melt kneader, or the like.

  The temperature at which the PAS prepolymer is melted and the cyclic PAS (a) and the linear PAS (b) are mixed is preferably a temperature range in which the cyclic PAS is difficult to convert to PAS, for example, 300 ° C. or less. Can be illustrated. Below 300 ° C, cyclic PAS tends to be difficult to convert.

  In addition, the cyclic PAS (a) and the linear PAS (b) are uniformly made in advance using the above-described mechanical mixing method, mixing method using a solvent, and melting and mixing cyclic polyarylene sulfide. There can also be a production process in which a mixed PAS prepolymer is obtained and added to the cyclic PAS (a).

<Method for producing polyarylene sulfide>
The above-described PAS of the present invention is produced by heating the PAS prepolymer to convert it to a high degree of polymerization. The heating temperature is preferably a temperature at which the PAS prepolymer melts, and there is no particular limitation as long as it is such a temperature condition. When the heating temperature is lower than the melt solution temperature of the PAS prepolymer, a long time tends to be required to obtain PAS. Although the temperature at which the PAS prepolymer melts varies depending on the composition and molecular weight of the PAS prepolymer and the environment during heating, it cannot be uniquely indicated. For example, the PAS prepolymer is a differential scanning calorimeter. It is possible to grasp the melting solution temperature by analyzing with. However, if the temperature is too high, undesirable side reactions such as cross-linking reactions and decomposition reactions between PAS prepolymers, between PASs generated by heating, and between PAS and PAS prepolymers tend to occur, It is desirable to avoid temperatures at which such undesirable side reactions are noticeable, since the properties of the resulting PAS may deteriorate. As heating temperature, 180-400 degreeC can be illustrated, Preferably it is 200-380 degreeC, More preferably, it is 250-360 degreeC.

  The heating time cannot be uniformly defined because it varies depending on various properties such as the cyclic PAS (a) content, the number of repeating units, and the molecular weight of the PAS prepolymer used, and the heating temperature. However, it is preferable to set so that the above-mentioned undesirable side reaction does not occur as much as possible. Examples of the heating time include 0.05 to 100 hours, preferably 0.1 to 20 hours, and more preferably 0.1 to 10 hours. If the time is less than 0.05 hours, the conversion of the PAS prepolymer to PAS tends to be insufficient, and if the time exceeds 100 hours, the possibility of adverse effects on the properties of the resulting PAS due to undesirable side reactions tends to become obvious. Not only that, but there may be economic disadvantages.

  The conversion of the PAS prepolymer to a high degree of polymerization by heating may be performed in a mold for producing a molded product, as well as by a method using a normal polymerization reaction apparatus, an extruder, Any apparatus equipped with a heating mechanism, such as a melt kneader, can be used without particular limitation, and known methods such as a batch method and a continuous method can be employed.

  It is also possible to heat the cyclic PAS under conditions that are substantially free of solvent. When carried out under such conditions, the temperature can be raised in a short time, the reaction rate is high, and PAS tends to be easily obtained in a short time. Here, the substantially solvent-free condition means that the solvent in the cyclic PAS is 10% by weight or less, and more preferably 3% by weight or less.

  The cyclic PAS can be heated under any of reduced pressure conditions, devolatilization conditions, atmospheric pressure conditions, and pressurized conditions. The atmosphere at this time is preferably a non-oxidizing atmosphere. The non-oxidizing atmosphere is an atmosphere in which the oxygen concentration in the gas phase in contact with the cyclic PAS is 5% by volume or less, preferably 2% by volume or less, more preferably an oxygen-free atmosphere, ie, nitrogen, helium, argon or the like. This indicates an active gas atmosphere, and among these, a nitrogen atmosphere is particularly preferred from the viewpoint of economy and ease of handling. Note that, under any pressure condition, it is preferable that the atmosphere in the reaction system is once changed to a non-oxidizing atmosphere and then heated under predetermined conditions. Thereby, it is in the tendency which can suppress generation | occurrence | production of undesirable side reactions, such as a crosslinking reaction and a decomposition reaction, and coloring between cyclic PAS, between PAS produced | generated by heating, and between PAS and cyclic PAS.

  The reduced pressure condition means that the reaction system is lower than atmospheric pressure, and the upper limit is preferably 50 kPa or less, more preferably 20 kPa or less, and even more preferably 10 kPa or less. An example of the lower limit is 0.1 kPa or more, and 0.2 kPa or more is more preferable. When the decompression condition is at least the preferred lower limit, the cyclic compound of the formula (B) having a low molecular weight contained in the cyclic PAS is less likely to be volatilized, whereas when it is less than the preferred upper limit, undesirable side reactions such as crosslinking reactions tend not to occur. A PAS having the above-described characteristics can be obtained.

  The devolatilization condition is a condition for removing a gaseous component generated when the cyclic PAS is heated from the heating system. The components in the gaseous state may vary depending on the type and content of the solvent, the composition and molecular weight of the cyclic PAS, the details of the devolatilizing component, etc. Examples thereof include PAS oligomers contained in PAS. The above conditions are not particularly limited as long as the generated gaseous component can be removed from the heating system, but for example, devolatilization under continuous decompression conditions, continuously flowing gas into the system, A condition for causing the generated gas state component to flow out of the heating system together with the inflowing gas, a condition for cooling the generated gas state component and collecting it outside the system, and the like can be mentioned. By heating under devolatilization conditions, the solvent and the PAS oligomer in the cyclic PAS hardly remain in the heating system, and the weight ratio of the cyclic PAS in the heating system tends to increase. The weight average molecular weight of PAS obtained by the above production method tends to increase, which is preferable.

  In the devolatilization under the continuous decompression condition, the continuous decompression condition is not limited as long as the generated gaseous component can be removed from the heating system, for example, the entire system in which the polymerization reaction is performed continuously. It may be reduced in pressure, or when heated using a mold for producing a molded article, an extruder or a melt kneader, etc., in a mold under normal pressure or pressurized conditions, in an extruder, in a melt kneader, etc. May be connected to a decompression device and continuously decompressed. By performing devolatilization under reduced pressure continuously, the solvent and PAS oligomer contained in the cyclic PAS can be more efficiently removed from the heating system, so that a PAS with a higher degree of polymerization tends to be obtained. .

  Although the temperature of the gas flowing into the system depends on the flow rate of the flowing gas, the heating temperature in the system, and the structure of the reaction system, there is no particular limitation as long as the heating temperature in the system can be stably controlled. However, from the viewpoint of stable gas temperature control, it is preferably 0 ° C. or higher, more preferably 20 ° C. or higher, further preferably 50 ° C. or higher, from the viewpoint of stable heating temperature control in the system. Is more preferably 100 ° C. or higher, more preferably 150 ° C. or higher, further preferably 180 ° C. or higher, and an even more preferable range is the same temperature as the heating temperature in the system. it can.

  The flow rate of the gas flowing into the system depends on the temperature of the gas flowing in, the heating temperature in the system, and the structure of the reaction system, but the gaseous component generated when the cyclic PAS is heated is the heating system. There is no particular limitation as long as it can be removed from the inside and the heating temperature in the system can be stably controlled. In terms of the effect of removing the generated gaseous component from the heating system, the flow rate of the gas flowing into the system per minute is preferably 1% or more of the volume in the system, and is preferably 5% or more. It is more preferable that it is 10% or more, and it is more preferable that it is 20% or more.

  The pressurized condition means that the inside of the system in which the reaction is carried out is higher than atmospheric pressure, and there is no particular upper limit, but it is preferably 0.2 MPa or less from the viewpoint of easy handling of the reaction apparatus. Moreover, the above-mentioned conversion of the PAS prepolymer to PAS can be carried out in the presence of a filler. Examples of the filler include fibrous or non-fibrous glass, fibrous or non-fibrous carbon, and inorganic fillers such as calcium carbonate, titanium oxide, and alumina.

<Polyarylene sulfide>
The PAS in the present invention is composed of an arylene group (hereinafter sometimes abbreviated as Ar) and a sulfide, and a repeating unit of the formula-(Ar-S)-as a main constituent unit, preferably 80 mol of the repeating unit. % Homopolymer or copolymer. Ar includes units represented by the above formulas (B) to (L), among which the formula (B) is particularly preferable.

  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 above formulas (M) to (O). 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 PAS in the present invention may be any of a random copolymer containing the above repeating unit, a block copolymer, and a mixture thereof.

  Typical examples thereof include polyphenylene sulfide, polyphenylene sulfide sulfone, polyphenylene sulfide ketone, random copolymers thereof, block copolymers, and mixtures thereof. Particularly preferred PASs include polyphenylene sulfide (hereinafter sometimes abbreviated as PPS) containing 80 mol% or more, particularly 90 mol% or more of p-arylene sulfide units as the main structural unit of the polymer, polyphenylene sulfide sulfone, Examples include polyphenylene sulfide ketone.

  The molecular weight of PAS obtained by heating the PAS prepolymer of the present invention is 10,000 or more in terms of weight average molecular weight, preferably 15000 or more, more preferably 18000 or more. When the weight average molecular weight is less than 10,000, the moldability at the time of processing is low, and the properties such as mechanical strength and chemical resistance of the molded product are low. Although there is no restriction | limiting in particular in the upper limit of a weight average molecular weight, Less than 100,000 can be illustrated as a preferable range, More preferably, it is less than 90000, More preferably, it is less than 80000, Especially high moldability can be obtained in this range. In the present invention, the weight average molecular weight of PAS obtained by controlling the mixing ratio of cyclic PAS and linear PAS in the PAS prepolymer and the value represented by X in the PAS prepolymer in the above-described PAS production method. Can be controlled to an arbitrary value within the above range.

  The molecular weight spread of PAS obtained by heating the PAS prepolymer in the present invention, that is, the dispersity represented by the ratio of the weight average molecular weight to the number average molecular weight (weight average molecular weight / number average molecular weight) is 2.5 or less. Yes, 2.3 or less is more preferable, 2.1 or less is more preferable, and 2.0 or less is even more preferable. Here, the preferable lower limit of the dispersity is 1.0, which means that PAS has a single molecular weight. Therefore, although the theoretical lower limit is 1.0, it is usually 1.5 or more in the PAS of the present invention. When the degree of dispersion exceeds 2.5, there is a strong tendency for low molecular weight components contained in PAS to increase, which means that mechanical properties are reduced when PAS is used for molding processing, and the amount of gas generated when heated is increased. In addition, it tends to be a factor such as an increase in the amount of the eluted component when in contact with the solvent. In addition, the said weight average molecular weight and number average molecular weight can be calculated | required, for example using SEC (size exclusion chromatography) equipped with the differential refractive index detector.

The PAS obtained by the production method of the present invention is characterized in that the amount of gas generated during melting is small. This gas generation amount can be evaluated from the weight reduction rate ΔWr when heated, which is obtained by a general thermogravimetric analysis and is represented by the following formula.
ΔWr = (W1-W2) / W1 × 100 (I)

  Here, ΔWr is a weight reduction rate (%), and when 100 ° C. is reached when thermogravimetric analysis is performed from 50 ° C. to 330 ° C. at a heating rate of 20 ° C./min in a normal pressure non-oxidizing atmosphere This is a value obtained from the sample weight (W2) when reaching 330 ° C. based on the sample weight (W1).

  The atmosphere in this analysis is a normal pressure non-oxidizing atmosphere. A non-oxidizing atmosphere is an atmosphere in which the oxygen concentration in the gas phase in contact with the sample is 5% by volume or less, preferably 2% by volume or less, more preferably an oxygen-free atmosphere, that is, an inert gas such as nitrogen, helium, or argon. A nitrogen atmosphere is particularly preferred from the standpoints of economy and ease of handling. The normal pressure is a pressure in the vicinity of the standard state of the atmosphere, and is an atmospheric pressure condition in which the temperature is about 25 ° C. and the absolute pressure is about 101.3 kPa. If the measurement atmosphere is other than the above, there is a possibility that oxidation of PAS may occur during measurement, and it may not be possible to measure in accordance with the actual use of PAS, such as greatly different from the atmosphere actually used in the molding process of PAS. Sex occurs.

  In the measurement of ΔWr, thermogravimetric analysis is performed by increasing the temperature from 50 ° C. to 330 ° C. at a temperature increase rate of 20 ° C./min. Preferably, after holding at 50 ° C. for 1 minute, the temperature is increased at a rate of temperature increase of 20 ° C./min to perform thermogravimetric analysis. This temperature range is a temperature range frequently used when actually using a PAS represented by polyphenylene sulfide, and is also a temperature range frequently used when a solid state PAS is melted and then molded into an arbitrary shape. is there. The weight reduction rate in the actual use temperature region is related to the amount of gas generated from the PAS during actual use, the amount of components adhering to the die, the mold, and the like during the molding process. Therefore, it can be said that a PAS having a lower weight loss rate in such a temperature range is an excellent PAS having a high quality. It is desirable to measure ΔWr with a sample amount of about 10 mg, and the shape of the sample is desirably a fine particle of about 2 mm or less.

  In the PAS of the present invention, ΔWr is 0.18% or less, preferably 0.12% or less, more preferably 0.10% or less, and even more preferably 0.085% or less. preferable. Here, there is no lower limit to ΔWr, and it is preferable that ΔWr is smaller. However, if a specific numerical value is exemplified, the lower limit value of ΔWr is 0.001%. When △ Wr exceeds the above range, for example, there is a tendency that a problem that the amount of gas generated is large when molding PAS, for example, and it is not preferable. In addition, a die or a die at the time of extrusion molding, or at the time of injection molding The amount of deposits on the mold increases and the productivity tends to deteriorate. As far as the present inventors know, ΔWr of known PAS obtained by reacting in the above organic solvent exceeds 0.18%, but PAS obtained by the preferred production method of the present invention has molecular weight distribution and impurity content. Unlike the known PAS, the amount is extremely high, so it is assumed that the value of ΔWr is remarkably lowered.

  The PAS having such characteristics is preferably produced by heating the PAS prepolymer and converting it to a high degree of polymerization as described above. Although the conversion to a high degree of polymerization will be described in detail later, the weight fraction of the cyclic PAS contained in the PAS obtained after the treatment for converting the cyclic PAS to a high degree of polymerization is 40% or less. Preferably, PAS of 25% or less, more preferably 15% or less, is preferable because the value of ΔWr is particularly small. When this value exceeds the above range, the value of ΔWr tends to increase, and although the cause is not clear at present, it is assumed that the cyclic PAS contained in the PAS is partially volatilized during heating.

  As described above, the PAS of the present invention has an excellent feature that the heating loss ΔWr when the temperature is raised is small, but has an excellent feature that the heating loss when holding the PAS at an arbitrary constant temperature is also small. Tend.

<Characteristics of PAS of the present invention>
The PAS of the present invention is excellent in heat resistance, chemical resistance, flame retardancy, electrical properties and mechanical properties, and in particular, has a narrow molecular weight distribution compared to conventional PAS, a small amount of gas during heating and a molecular weight. Because it is controlled, it has excellent molding processability, mechanical properties, and electrical properties. Extrusion of sheets, films, fibers, pipes, etc. not only by injection molding, injection compression molding, and blow molding, but also by extrusion molding. Can be molded and used for molded products.

  As a method for producing a PAS film using the PAS of the present invention, a known melt film-forming method can be employed. For example, after melting PAS in a single-screw or twin-screw extruder, it is extruded from a film die, Examples thereof include a method of producing a film by cooling on a cooling drum, or a biaxial stretching method in which a film thus produced is stretched in the longitudinal and transverse directions by a roller-type longitudinal stretching apparatus and a transverse stretching apparatus called a tenter. However, it is not particularly limited to this.

  As a method for producing a PAS fiber using the PAS of the present invention, a known melt spinning method can be applied. For example, a PAS chip as a raw material is kneaded while being supplied to a single-screw or twin-screw extruder, Next, a method of extruding from a spinneret through a polymer stream line changer installed at the tip of the extruder, a filtration layer, etc., cooling, stretching, heat setting, etc. can be adopted, but this is particularly limited is not.

  In addition, the PAS of the present invention may be used alone or, if desired, an inorganic filler such as glass fiber, carbon fiber, titanium oxide, calcium carbonate, antioxidant, heat stabilizer, ultraviolet absorber, Colorants can also be added, such as polyamide, polysulfone, polyphenylene ether, polycarbonate, polyether sulfone, polyester represented by polyethylene terephthalate and polybutylene terephthalate, polyethylene, polypropylene, polytetrafluoroethylene, epoxy group, carboxyl group, Olefin copolymers having functional groups such as carboxylic acid ester groups and acid anhydride groups, polyolefin elastomers, polyether ester elastomers, polyether amide elastomers, polyamide imides, polyacetals, polyimides Any resin may also be mixed.

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

<Molecular weight measurement>
The molecular weights of PAS and linear PAS were measured by gel permeation chromatography (GPC), and the number average molecular weight (Mn) and weight average molecular weight (Mw) were calculated in terms of polystyrene. The measurement conditions for GPC are shown below.
Equipment: Senshu Science SSC-7110
Column name: Senshu Science Shodex UT 806M × 2
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).

<Measurement of cyclic polyarylene sulfide content>
Calculation of cyclic PAS content of cyclic PAS (a), linear PAS (b), PAS prepolymer, and PAS was performed by the following method using high performance liquid chromatography (HPLC).

About 10 mg of cyclic PAS (a), linear PAS (b), PAS prepolymer, and PAS were dissolved in about 5 g of 1-chloronaphthalene at 250 ° C. A precipitate formed upon cooling to room temperature. The 1-chloronaphthalene insoluble component was filtered using a membrane filter having a pore size of 0.45 μm to obtain a 1-chloronaphthalene soluble component. The amount of unreacted cyclic PAS was quantified by HPLC measurement of the obtained soluble component, and the conversion rate of cyclic PAS to PAS was calculated. The measurement conditions for HPLC are shown below.
Apparatus: Shimadzu Corporation LC-10Avp series Column: Mightysil RP-18 GP150-4.6 (5 μm)
Detector: Photodiode array detector (UV = 270 nm).

<Solid-liquid separation of reaction mixture>
200 g of the resulting reaction mixture was collected and charged into a 300 mL flask. The reaction mixture was stirred using a magnetic stirrer and heated to 100 ° C. in an oil bath while nitrogen bubbling was performed on the slurry of the reaction mixture.

  ADVANTEC's universal tank filter holder KST-90-UH (effective filtration area approximately 45 square centimeters) with a polytetrafluoroethylene (PTFE) membrane filter with a diameter of 90 mm and an average pore diameter of 10 μm Was adjusted to 100 ° C. with a hand heater.

  The reaction mixture heated to 100 ° C. was charged into the tank, and after sealing the tank, the inside of the tank was pressurized to 0.1 MPa with nitrogen.

<Measurement of weight loss rate during heating of PAS>
The weight reduction rate during heating of the PAS was performed under the following conditions using a thermogravimetric analyzer. In addition, the sample used the fine granule of 2 mm or less.
Apparatus: Perkin Elmer TGA7
Measurement atmosphere: Sample preparation weight under nitrogen stream: Approximately 10 mg
Measurement condition:
(A) Hold for 1 minute at a program temperature of 50 ° C. (b) Increase the temperature from the program temperature of 50 ° C. to 400 ° C. Temperature increase rate at this time 20 ° C / min

The weight reduction rate ΔWr was calculated from the sample weight when the temperature reached 330 ° C. using the following formula, based on the sample weight at 100 ° C., at the temperature rise of (b).
ΔWr = (W1-W2) / W1 × 100
(Here, ΔWr is the weight loss rate (%), and when the thermogravimetric analysis was performed from 50 ° C. to 330 ° C. at a heating rate of 20 ° C./min in a normal pressure non-oxidizing atmosphere, when 100 ° C. was reached. This is a value obtained from the sample weight (W2) when reaching 330 ° C. based on the sample weight (W1).

[Example 1]
<Step 1: Synthesis of reaction mixture>
In a stainless steel autoclave equipped with a stirrer, 28.1 g of a 48 wt% aqueous sodium hydrosulfide solution (0.241 mol as sodium hydrosulfide) as a sulfiding agent, 21.1 g of a 48 wt% aqueous sodium hydroxide solution (as sodium hydroxide) 0.253 mol), 35.4 g (0.241 mol) of p-dichlorobenzene (p-DCB) as a dihalogenated aromatic compound, and 600 g of N-methyl-2-pyrrolidone (NMP) as an organic polar solvent (6. The reaction raw material was prepared by charging (05 mol). The amount of water contained in the raw material is 25.6 g (1.42 mol), and the amount of solvent per mole of sulfur component in the reaction mixture (per mole of sulfur atoms contained in sodium hydrosulfide charged as a sulfidizing agent) Was about 2.43 L. Further, the amount of arylene units (corresponding to the charged p-DCB) per 1 mol of the sulfur component in the reaction mixture (per 1 mol of sulfur atom contained in the charged sodium hydrosulfide) was 1.00 mol.

  The inside of the autoclave was sealed after being replaced with nitrogen gas, and the temperature was raised from room temperature to 200 ° C. over about 1 hour while stirring at 400 rpm. Next, the temperature was raised from 200 ° C. to 250 ° C. over about 0.5 hour. The pressure in the reactor at this stage was 1.05 MPa as a gauge pressure. Thereafter, the reaction mixture was heated at 250 ° C. for 2 hours to be reacted.

  An NMP solution of p-DCB (3.54 g of p-DCB was dissolved in 10 g of NMP) was charged into a 100 mL small tank installed at the top of the autoclave via a high pressure valve. After pressurizing the inside of the small tank to about 1.5 MPa, the valve at the bottom of the tank was opened, and an NMP solution of p-DCB was charged into the autoclave. After washing the wall surface of the small tank with 5 g of NMP, this NMP was also charged into the autoclave. With this operation, the number of arylene units per mole of sulfur component in the reaction mixture (corresponding to the total amount of charged p-DCB) was 1.10 moles. After the completion of this additional charging, the reaction was continued by continuing heating at 250 ° C. for an additional hour. Then, after cooling to 230 ° C. over about 15 minutes, by gradually opening the high-pressure valve installed at the top of the autoclave, the vapor mainly composed of NMP is discharged, and this vapor component is aggregated in the water-cooled cooling pipe, After recovering about 391 g of liquid components, the high pressure valve was closed and sealed. Next, the reaction mixture was recovered by quenching to near room temperature.

  A part of the obtained reaction mixture was dispersed in a large excess of water to recover water-insoluble components, and the recovered water-insoluble components were dried to obtain a solid content. As a result of structural analysis by infrared spectroscopic analysis, it was confirmed that the solid content was a compound comprising an arylene sulfide unit.

  As a result of analyzing the obtained reaction mixture and the liquid components recovered by the liquid removal operation after the reaction by gas chromatography, high performance liquid chromatography and ion chromatography, the reaction consumption rate of sodium hydrosulfide used as a sulfidizing agent was 97. %Met.

<Step 2: Recovery of linear PAS (b)>
The reaction mixture was subjected to solid-liquid separation by the above solid separation operation to obtain solid-state linear PAS (b). About 10 times the amount of ion-exchanged water was added to the obtained solid content in a wet state to disperse it into a slurry, and the resulting slurry was stirred at 80 ° C. for 15 minutes. The operation of suction filtration with a glass filter was repeated a total of 4 times. The obtained solid was treated at 70 ° C. for 3 hours in a vacuum dryer to obtain a dry solid as linear PAS (b).

  As a result of analysis of this isolated dry solid, it was found that it was PAS, the weight average molecular weight was 9000, the number average molecular weight was 3600, and the cyclic PAS content was 3% from the absorption spectrum in infrared spectroscopy. It was.

<Step 3: Recovery of cyclic PAS (a)>
100 g of the filtrate obtained by the solid-liquid separation operation in the above step 2 (2 wt% in the concentration of cyclic PAS) was charged into a 300 mL flask, and the inside of the flask was replaced with nitrogen. Next, the mixture was heated to 100 ° C. with stirring and then cooled to 80 ° C. Subsequently, 33 g of water was slowly added dropwise over about 15 minutes using a pump while stirring at an internal temperature of 80 ° C. Here, the weight ratio of NMP to water in the filtrate mixture after completion of the dropwise addition of water was 75:25. In the addition of water to the filtrate, the temperature of the mixture decreases to about 75 ° C. along with the dropwise addition of water, and solids are gradually formed in the mixture. A slurry was obtained. The slurry was cooled to about 30 ° C. over about 1 hour with stirring, and then stirred for about 30 minutes at about room temperature. The resulting slurry was filtered with suction through a glass filter having an opening of 10 to 16 μm. The obtained solid content (including the mother liquor) was dispersed in about 100 g of water, stirred for 15 minutes at 80 ° C., and then subjected to suction filtration with a glass filter in the same manner as described above four times. The obtained solid was treated at 70 ° C. for 3 hours in a vacuum dryer to obtain a dry solid as cyclic PAS (a).

  As a result of analyzing the dried solid by HPLC, cyclic PAS having 4 to 15 units was detected. Moreover, the content rate of cyclic PAS in a dry solid was 89 weight%, and it turned out that the obtained dry solid is cyclic PAS with high purity.

  900 mg of the obtained cyclic PAS (a) and 100 mg of linear PAS (b) were mixed in a mortar to obtain a PAS prepolymer. Here, the weight fraction of linear PAS (b) in the PAS prepolymer is 0.10, and the weight ratio of cyclic PAS to linear PAS (cyclic PAS / linear PAS) is 3.8, represented by X. The value to be done is 60. As a result of HPLC measurement, the content of cyclic PAS in the PAS prepolymer was 79%.

  300 mg of the obtained PAS prepolymer was charged into a glass ampule, and the inside of the ampule was replaced with nitrogen. The ampule was allowed to stand in an electric furnace adjusted to 340 ° C. and heated for 4 hours, and then the ampule was taken out and cooled to room temperature to obtain a brown solid. The product was completely dissolved in 1-chloronaphthalene at 250 ° C. As a result of HPLC measurement, the content of cyclic PAS in the product was 12%, and as a result of GPC measurement, a peak derived from cyclic PAS and a peak derived from generated PAS could be confirmed, and the weight of the obtained PAS The average molecular weight was found to be 58,000 and the dispersity was 2.5. Moreover, as a result of measuring the weight loss rate by heating of the obtained product, ΔWr was 0.067%.

[Example 2]
850 mg of cyclic PAS (a) obtained by the same operation as in Example 1 and 150 mg of linear PAS (b) were mixed in a mortar to obtain a PAS prepolymer. Here, the weight fraction of linear PAS (b) in the PAS prepolymer is 0.15, the weight ratio of cyclic PAS to linear PAS is 2.8, and the value represented by X is 90. As a result of HPLC measurement of the PAS prepolymer, the content of cyclic PAS in the PAS prepolymer was 74%.
Using this PAS prepolymer, the same polymerization operation as in Example 1 was performed to obtain a brown solid. The product was completely dissolved in 1-chloronaphthalene at 250 ° C. As a result of HPLC measurement, the content of cyclic PAS in the product was 11%. As a result of GPC measurement, a peak derived from cyclic PAS and a peak derived from generated PAS could be confirmed, and the weight of the obtained PAS The average molecular weight was found to be 51000 and the dispersity was 2.5. Moreover, as a result of measuring the weight loss rate by heating of the obtained product, ΔWr was 0.048%.

[Comparative Example 1]
300 mg of the cyclic PAS (a) obtained in Example 1 was charged into a glass ampule, and the inside of the ampule was replaced with nitrogen. The ampule was allowed to stand in an electric furnace adjusted to 340 ° C. and heated for 4 hours, and then the ampule was taken out and cooled to room temperature to obtain a brown solid. The product was completely dissolved in 1-chloronaphthalene at 250 ° C. As a result of HPLC measurement, the content of cyclic PAS in the product was 12%, and as a result of GPC measurement, a peak derived from cyclic PAS and a peak derived from generated PAS could be confirmed, and the weight of the obtained PAS The average molecular weight was found to be 83000 and the dispersity was 2.5. Moreover, as a result of measuring the weight loss rate by heating of the obtained product, ΔWr was 0.046%.

  From the comparison of the weight average molecular weight exemplified in Examples 1 and 2 and the weight average molecular weight shown in Reference Example 1, the effect of reducing the molecular weight could be confirmed by mixing linear PAS (b) with the PAS prepolymer. Moreover, it was confirmed from the comparison between Examples 1 and 2 that the molecular weight obtained by controlling the mixing ratio of linear PAS (b) in the PAS prepolymer and the value represented by X can be arbitrarily controlled.

[Example 3]
A cyclic PAS (a) and a linear PAS (b) were obtained by performing the same operation as in Example 1 except that the same operation as in Example 1 was performed at a scale of 10.

As a result of analyzing the dry solid of cyclic PAS (a) by HPLC, cyclic PAS having 4 to 15 units was detected. Moreover, the content rate of cyclic PAS in dry solid was 82 weight%, and it turned out that the obtained dry solid is cyclic PAS with high purity.
As a result of analysis of the dried solid of linear PAS (b), it was found that it was PAS from the absorption spectrum in infrared spectroscopic analysis, the weight average molecular weight was 9100, the number average molecular weight was 3800, and the cyclic PAS content was 2 %Met.

  900 mg of the obtained cyclic PAS (a) and 100 mg of linear PAS (b) were mixed in a mortar to obtain a PAS prepolymer. Here, the weight fraction of linear PAS (b) in the PAS prepolymer is 0.10, the weight ratio of cyclic PAS to linear PAS is 2.6, and the value represented by X is 57. As a result of HPLC measurement of the PAS prepolymer, the content of cyclic PAS in the PAS prepolymer was 72%.

  Using the obtained PAS prepolymer, the same polymerization operation as in Example 1 was performed to obtain a brown solid. The product was completely dissolved in 1-chloronaphthalene at 250 ° C. As a result of HPLC measurement, the content of cyclic PAS in the product was 11%. As a result of GPC measurement, a peak derived from cyclic PAS and a peak derived from generated PAS could be confirmed, and the weight of the obtained PAS The average molecular weight was found to be 34000 and the degree of dispersion was 2.1.

[Comparative Example 2]
A brown solid was obtained in the same manner as in Comparative Example 1 except that the cyclic PAS (a) obtained in Example 3 was used. The product was completely dissolved in 1-chloronaphthalene at 250 ° C. As a result of HPLC measurement, the content of cyclic PAS in the product was 6%, and as a result of GPC measurement, a peak derived from cyclic PAS and a peak derived from generated PAS were confirmed, and the weight of the obtained PPS It was found that the average molecular weight was 43,000 and the degree of dispersion was 2.3.

  From the comparison of the weight average molecular weight exemplified in Example 3 and the weight average molecular weight shown in Comparative Example 2, the effect of reducing the molecular weight could be confirmed by mixing linear PAS (b) with the PAS prepolymer.

[Reference Example 1 Synthesis of polyphenylene sulfide resin]
In an autoclave, 118% (1 mol) of 47% sodium hydrosulfide, 42.9 g (1.03 mol) of 96% sodium hydroxide, 162 g (1.64 mol) of N-methyl-2-pyrrolidone (NMP), sodium acetate 28 0.8 g (0.35 mol) and 150 g of ion-exchanged water were added and gradually heated to 235 ° C. over about 3 hours while passing nitrogen at normal pressure, and 213 g of water and 4.0 g (40.4 mmol) of NMP were distilled. After dispensing, the reaction vessel was cooled to 160 ° C. The amount of hydrogen sulfide scattered was 25 mmol.

  Next, 148 g (1.01 mol) of p-dichlorobenzene (p-DCB) and 131 g (1.33 mol) of NMP were added, and the reaction vessel was sealed under nitrogen gas. While stirring at 400 rpm, the temperature was increased from 200 ° C. to 270 ° C. at a rate of 0.6 ° C./min, and the reaction was continued at 270 ° C. for 140 minutes. Thereafter, while cooling to 240 ° C. over 20 minutes, 33.3 g (1.85 mol) of water was injected into the system, and then cooled from 240 ° C. to 210 ° C. at a rate of 0.4 ° C./min. Thereafter, it was rapidly cooled to near room temperature.

  The contents were taken out and diluted with 400 milliliters of NMP, and then the solvent and solid matter were filtered off with a sieve (80 mesh). The obtained particles were washed again at 480 ml of NMP at 85 ° C. Thereafter, it was washed 5 times with 840 ml of warm water and filtered to obtain PPS polymer particles. This was heated under a nitrogen stream at 150 ° C. for 5 hours and then dried under reduced pressure at 150 ° C. overnight.

  The obtained PPS was found to have a weight average molecular weight of 55000 and a dispersity of 3.80. As a result of measuring the weight loss rate during heating of the obtained product, ΔWr was 0.251%.

[Reference Example 2]
A PPS was obtained in the same manner as in Reference Example 1, except that sodium acetate was not used. The obtained PPS was found to have a weight average molecular weight of 45,000 and a dispersity of 3.20. As a result of measuring the weight loss rate during heating of the obtained product, ΔWr was 0.253%.

  From the comparison of the weight loss rate during heating exemplified in Examples 1 and 2 and the weight loss rate during heating shown in Reference Examples 1 and 2, the present invention has a PPS having a lower weight loss rate during heating than the PPS obtained by the conventional method. I found out that

[Example 4]
500 mg of cyclic PAS (a) and 500 mg of linear PAS (b) obtained in the same manner as in Example 1 were mixed in a mortar to obtain a PAS prepolymer. Here, the weight fraction of linear PAS (b) in the PAS prepolymer is 0.50, the weight ratio of cyclic PAS to linear PAS is 0.8, and the value represented by X is 300. As a result of HPLC measurement of the PAS prepolymer, the content of cyclic PAS in the PAS prepolymer was 45%.

  Using this PAS prepolymer, the same polymerization operation as in Example 1 was performed to obtain a brown solid. The product was completely dissolved in 1-chloronaphthalene at 250 ° C. As a result of HPLC measurement, the content of cyclic PAS in the product was 4%, and as a result of GPC measurement, a peak derived from cyclic PAS and a peak derived from generated PAS were confirmed, and the weight of the obtained PAS It was found that the average molecular weight was 33600 and the degree of dispersion was 2.2. Moreover, as a result of measuring the weight loss rate by heating of the obtained product, ΔWr was 0.042%.

[Example 5]
A PAS prepolymer was obtained by mixing 100 mg of cyclic PAS (a) and 900 mg of linear PAS (b) obtained in the same manner as in Example 1 with a mortar. Here, the weight fraction of linear PAS (b) in the PAS prepolymer is 0.90, the weight ratio of cyclic PAS to linear PAS is 0.1, and the value represented by X is 540. As a result of HPLC measurement of the PAS prepolymer, the content of cyclic PAS in the PAS prepolymer was 8%.

  Using this PAS prepolymer, the same polymerization operation as in Example 1 was performed to obtain a brown solid. The product was completely dissolved in 1-chloronaphthalene at 250 ° C. As a result of HPLC measurement, the content of cyclic PAS in the product is 1%, and as a result of GPC measurement, a peak derived from the generated PAS can be confirmed. The weight average molecular weight of the obtained PAS is 26800, and the degree of dispersion is It was found to be 2.8. Moreover, as a result of measuring the weight loss rate by heating of the obtained product, ΔWr was 0.039%.

  From the comparison of the dispersibility exemplified in Examples 1 and 2 and 4 with the dispersity shown in Example 5, the amount of the linear PAS (b) mixed with the PAS prepolymer is within the preferred range of the present invention. It was found that PAS with a low degree of dispersion can be obtained while controlling the molecular weight.

[Example 6]
995 mg of cyclic PAS (a) obtained by the same operation as in Example 1 and 5 mg of linear PAS (b) were mixed in a mortar to obtain a PAS prepolymer. Here, the weight fraction of linear PAS (b) in the PAS prepolymer is 0.005, the weight ratio of cyclic PAS to linear PAS is 8.1, and the value represented by X is 3. As a result of HPLC measurement of the PAS prepolymer, the content of cyclic PAS in the PAS prepolymer was 89%.

  Using this PAS prepolymer, the same polymerization operation as in Example 1 was performed to obtain a brown solid. The product was completely dissolved in 1-chloronaphthalene at 250 ° C. As a result of HPLC measurement, the content of cyclic PAS in the product was 12%, and as a result of GPC measurement, a peak derived from cyclic PAS and a peak derived from generated PAS could be confirmed, and the weight of the obtained PAS The average molecular weight was found to be 83000 and the dispersity was 2.5.

  From the comparison of the weight average molecular weights exemplified in Examples 1, 2 and 4 and the weight average molecular weight shown in Example 6, the amount of the linear PAS (b) mixed with the PAS prepolymer should be within the preferred range of the present invention. It was found that the molecular weight can be controlled.

[Comparative Example 3]
300 mg of cyclic PAS (a) obtained by the same operation as in Example 1 and 700 mg of linear PAS obtained by the same operation as in Reference Example 2 were mixed in a mortar to obtain a PAS prepolymer. Here, the weight fraction of linear PAS in the PAS prepolymer is 0.7, the weight ratio of cyclic PAS to linear PAS is 0.3, and the value represented by X is 108. As a result of HPLC measurement of the PAS prepolymer, the content of cyclic PAS in the PAS prepolymer was 24%.

  Using this PAS prepolymer, the same polymerization operation as in Example 1 was performed to obtain a brown solid. The product was completely dissolved in 1-chloronaphthalene at 250 ° C. As a result of HPLC measurement, the content of cyclic PAS in the product was 4%, and as a result of GPC measurement, a peak derived from cyclic PAS and a peak derived from generated PAS were confirmed, and the weight of the obtained PAS It was found that the average molecular weight was 66700 and the degree of dispersion was 2.4.

[Comparative Example 4]
100 mg of cyclic PAS (a) obtained by the same operation as in Example 1 and 900 mg of linear PAS obtained by the same operation as in Reference Example 2 were mixed in a mortar to obtain a PAS prepolymer. Here, the weight fraction of linear PAS in the PAS prepolymer is 0.9, the weight ratio of cyclic PAS to linear PAS is 0.1, and the value represented by X is 139. As a result of HPLC measurement of the PAS prepolymer, the content of cyclic PAS in the PAS prepolymer was 8%.

  Using this PAS prepolymer, the same polymerization operation as in Example 1 was performed to obtain a brown solid. The product was completely dissolved in 1-chloronaphthalene at 250 ° C. As a result of HPLC measurement, the content of cyclic PAS in the product is 1%, and as a result of GPC measurement, a peak derived from the generated PAS can be confirmed. The weight average molecular weight of the obtained PAS is 64900, and the degree of dispersion is It was found to be 2.6.

  From the comparison of the weight average molecular weights exemplified in Examples 1 and 2 and 4 and the weight average molecular weights shown in Comparative Examples 3 and 4, the weight average molecular weight of the linear PAS to be blended with the PAS prepolymer is within the preferred range of the present invention. Thus, it was found that the molecular weight can be controlled according to the blending amount of the linear PAS.

  The PAS prepolymer of the present invention is useful for controlling the molecular weight of the resulting PAS in a method for obtaining PAS by heating cyclic PAS. In addition, the useful PAS prepolymer can be easily obtained by the method for producing a PAS prepolymer of the present invention. Furthermore, PAS having a controlled molecular weight can be obtained by the PAS production method of the present invention.

Claims (11)

The cyclic polyarylene sulfide (a) containing at least 50% by weight of the cyclic polyarylene sulfide and having a weight average molecular weight of less than 10,000, and the content of the cyclic polyarylene sulfide is 5% by weight or less, and the weight A polyarylene sulfide prepolymer comprising a linear polyarylene sulfide (b) having an average molecular weight of from 5,000 to 20,000. The polyarylene sulfide prepolymer according to claim 1, wherein the polyarylene sulfide prepolymer comprises at least 30% by weight or more of a cyclic polyarylene sulfide prepolymer, and the polyarylene sulfide prepolymer has a weight average molecular weight of less than 10,000. 3. The weight ratio of cyclic polyarylene sulfide to linear polyarylene sulfide (cyclic polyarylene sulfide / linear polyarylene sulfide) contained in the polyarylene sulfide prepolymer is 0.5 or more and less than 1,000. The polyarylene sulfide prepolymer described in 1. The polyarylene sulfide prepolymer according to any one of claims 1 to 3, wherein X represented by the following formula is in the range of 1 to 400.
X = 2a / (Mn / M) × 10000
(Here, the weight fraction of linear polyarylene sulfide (b) in the polyarylene sulfide prepolymer: number average molecular weight of a and linear PAS (b): Mn, and the repeating unit molecular weight of polyarylene sulfide: M Value.) The method for producing a polyarylene sulfide prepolymer according to any one of claims 1 to 4, wherein the cyclic polyarylene sulfide (a) is produced by the following steps 1, 2 and 3, and the following steps 1 and 2 are produced. A method for producing a polyarylene sulfide prepolymer, in which a linear polyarylene sulfide (b) is produced by the method, and then a cyclic polyarylene sulfide (a) and a linear polyarylene sulfide (b) are mixed.
Step 1: Contacting at least a sulfidizing agent and a dihalogenated aromatic compound in an organic polar solvent to obtain a reaction mixture containing at least a cyclic polyarylene sulfide (a) and a linear polyarylene sulfide (b) .
Process 2: The process of solid-liquid separating the reaction mixture obtained through the said process 1, and obtaining linear polyarylene sulfide (b) as solid content.
Step 3: A step of obtaining cyclic polyarylene sulfide (a) as a solid content from an organic polar solvent containing at least cyclic polyarylene sulfide obtained by solid-liquid separation of the reaction mixture obtained through Step 1 above. When the weight ratio of the cyclic polyarylene sulfide (a) is 100, the cyclic polyarylene sulfide (a) and the linear polyarylene are in a range where the weight ratio of the linear polyarylene sulfide (b) is 0.1 to 200. The method for producing a polyarylene sulfide prepolymer according to claim 5, wherein the sulfide (b) is mixed. The method for producing a polyarylene sulfide prepolymer according to claim 5 or 6, wherein the step 1 is carried out in an organic polar solvent of 1.25 to 50 liters per 1 mol of the sulfur component. The method for producing a polyarylene sulfide prepolymer according to any one of claims 5 to 7, wherein the linear polyarylene sulfide (b) is produced by a step of washing the obtained linear polyarylene sulfide after the step 2 with a solvent. . A method for producing polyarylene sulfide, wherein the polyarylene sulfide prepolymer according to any one of claims 1 to 4 is heated to be converted into a high degree of polymerization having a weight average molecular weight of 10,000 or more. A polyarylene sulfide prepolymer is obtained by the method for producing a polyarylene sulfide prepolymer according to any one of claims 5 to 8, and then the polyarylene sulfide prepolymer is heated to obtain a high degree of polymerization having a weight average molecular weight of 10,000 or more. A process for producing polyarylene sulfide to be converted into The method for producing polyarylene sulfide according to claim 9 or 10, wherein the obtained polyarylene sulfide satisfies the following (1) to (3).
(1) The weight average molecular weight is 10,000 or more.
(2) The degree of dispersion represented by weight average molecular weight / number average molecular weight is 2.5 or less.
(3) The weight reduction rate ΔWr when heated satisfies the following formula.
ΔWr = (W1-W2) /W1×100≦0.18 (%)
(Here, ΔWr is the weight loss rate (%), and when the thermogravimetric analysis was performed from 50 ° C. to 330 ° C. at a heating rate of 20 ° C./min in a normal pressure non-oxidizing atmosphere, when 100 ° C. was reached. (It is a value obtained from the sample weight (W2) when reaching 330 ° C. based on the sample weight (W1))