JP2015127398A - Polyarylene sulfide and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide polyarylene sulfide achieving both of high quality with generation gas or chlorine content reduced during molding processing and high flowability during melting processing.SOLUTION: There is provided a method for manufacturing polyarylene sulfide by reacting a reaction mixture containing at least a sulfide agent (a), a dihalogenated aromatic compound (b) and an organic polar solvent (c) with 1.25 liter to 50 liter of the organic polar solvent (c) based on 1 mol of a sulfur component in the reaction mixture and isolating polyarylene sulfide having a weight average molecular weight of 2,500 to 20,000 from a reaction product obtained from following process 1 and process 2. The process 1 is a process of heating the reaction mixture having an arylene unit of 0.80 mol or more and less than 1.05 mol per 1 mol of the sulfur component in the reaction mixture and reacting until 50% or more of the sulfide agent (a) in the reaction mixture is consumed. The process 2 is a process of adding the dihalogenated aromatic compound (b) so that the arylene unit per 1 mol of the sulfur component in the reaction mixture becomes 1.05 mol to 1.50 mol and then conducting a reaction by further heating to obtain the reaction product containing polyarylene sulfide.

Description

  The present invention relates to polyarylene sulfide and a method for producing the same. More specifically, the present invention relates to a polyarylene sulfide that is eagerly desired as a polyarylene sulfide resin and has both a high quality in which a gas generated during molding processing and contained chlorine are reduced, and a high fluidity during melt processing, and a method for producing the same.

  In recent years, international chemical substance regulations such as RoHS regulations and REACH regulations are increasing, and in the field of electrical and electronic parts, there is an active movement toward lower halogens as an environmental effort. For example, in general-purpose resins, halogen-based flame retardants are often used to impart flame retardancy, but from the trend of low halogenation, resins that can obtain sufficient flame resistance without halogen-based flame retardants are attracting attention. . Among them, a polyarylene sulfide (hereinafter sometimes abbreviated as PAS) resin represented by polyphenylene sulfide (hereinafter also abbreviated as PPS) has high flame retardancy without using a halogen-based flame retardant. At the same time, it has attracted attention as a halogen-based flame retardant-free resin because it has excellent properties such as chemical resistance, heat and humidity resistance, barrier properties, and electrical insulation.

  However, when a dihalogenated aromatic compound and a sulfidizing agent, which are general PAS production methods, are used as raw materials, the halogen derived from the dihalogenated aromatic compound is present in the molecular chain terminal at an arbitrary ratio. The resin itself exhibits a high halogen content. Further, the PAS recovery method after completion of the polymerization reaction also affects the halogen content. In general, the oligomer component produced simultaneously with the production of PAS exhibits a high halogen content.

  Here, in the flash method in which the polymerization reaction product is flushed from a high-temperature and high-pressure state into an atmosphere of normal pressure or reduced pressure, and the polymer is powdered and recovered at the same time as the solvent recovery, PAS containing oligomer components that are nonvolatile components is recovered. (For example, Patent Document 1). In this flash method, since it is possible to recover a PAS having a low molecular weight, there is a tendency to obtain a PAS excellent in fluidity at the time of melt processing. On the other hand, since it contains an oligomer component, it is as high as about 5000 ppm. Indicates the halogen content.

  On the other hand, in the quench method, the polymerization reaction product is gradually cooled from a high temperature and high pressure state to precipitate a PAS component in the reaction system, and the oligomer component is removed by wire mesh separation to obtain PAS. This quench method shows a lower halogen content compared to the flash method. However, since the oligomer method is removed in the quench method, the production tends to be limited to high molecular weight PAS, and the tendency to become PAS having poor fluidity is strong (for example, Patent Document 2).

  As an example in which the halogen (chlorine) content is reduced by the conventional method for producing polyarylene sulfide as described above, for example, Patent Document 3 discloses a polyarylene sulfide resin having a chlorine atom content of 1,500 to 2,000 ppm ( Although A) is disclosed, this polyarylene sulfide resin (A) has a molecular weight of 25,000 to 30,000, and a polyarylene sulfide excellent in fluidity with a molecular weight of 20,000 or less has not been obtained.

  Further, for example, Patent Document 4 discloses a polyarylene sulfide (a) having a chlorine content of 1200 to 1600 ppm, and this polyarylene sulfide (a) is an improved type equipped with a die having a diameter of 1 mm and a length of 2 mm. It is a linear polyphenylene sulfide having a melt viscosity of 200 to 2000 poise measured under the conditions of a measurement temperature of 315 ° C. and a load of 10 kg using a flow tester. Usually, the molecular weight of PPS having a melt viscosity of 200 poise or more is larger than 20,000. Therefore, a polyarylene sulfide having a molecular weight of 20,000 or less and excellent fluidity was not obtained.

  As described above, in the prior art in PAS production, there is a trade-off relationship between the reduction of chlorine content and good fluidity (low molecular weight) during molding processing, and PPS that achieves both reduction of chlorine content and low molecular weight. It was difficult to get.

  Further, as another problem other than the halogen content in PAS, there has been a problem that volatile components contained in PAS are volatilized when melt kneading and injection molding of PAS, that is, when PAS is melted. The volatile component at the time of melting and heating causes clogging of the degassing part (vent part) of the processing apparatus used for melting processing, resulting in a problem that the operability is deteriorated, or when volatilized substances are released into the atmosphere. Reduction of the volatile components at the time of melting is desired because it is an increase in environmental load, and also a factor that deteriorates mold contamination and the surface quality of a molded product when a molded product of PAS is manufactured.

  Here, as a method for reducing the volatile components in PAS, a sulfidizing agent (NaSH) and a dihalogenated aromatic in N-methyl-2-pyrrolidone (hereinafter sometimes abbreviated as NMP) which is an organic polar solvent. A method of removing the oligomer component by reacting the compound (p-dichlorobenzene), washing the polymer slurry obtained by the reaction with NMP, and further washing the obtained polymer with a solvent can be exemplified (for example, Patent Document 5). ). This method is expected to reduce the chlorine content as well as the volatile components derived from the oligomer component decomposition by reducing the oligomer components by solvent washing. However, there is a limit in reducing the chlorine content because chlorine is still present at the molecular chain end of the recovered PAS.

  Among these problems in the prior art, as a method for realizing a drastic reduction of the halogen content, a method of using a monohalogenated aromatic compound or a thiol compound together with a dihalogenated aromatic compound as a raw material has been proposed ( For example, see Patent Documents 6 to 8.) In these methods, a monohalogenated aromatic compound or a thiol compound used in combination is introduced into the terminal of the polyarylene sulfide to be produced, so that the halogen content of the polyarylene sulfide is expected to be reduced. However, in these methods, it is necessary to efficiently copolymerize a monohalogenated aromatic compound or a thiol compound having a different reactivity from the dihalogenated aromatic compound as the main raw material. Therefore, these methods require strict reaction control such that a monohalogenated aromatic compound or a thiol compound is further reacted after a certain amount of the dihalogenated aromatic compound has reacted, and at the same time, after the reaction, This method has a problem that a complicated production process for separating and recovering the dihalogenated aromatic compound, the monohalogenated aromatic compound, and the thiol compound remaining as reactants is essential.

  In addition, in high quality methods represented by these Patent Documents 1 to 8, such as a method for reducing the halogen content of polyarylene sulfide and a method for reducing the amount of volatile components at the time of melting, maintaining high fluidity at the time of melt processing, That is, achieving both the production and quality of low molecular weight PAS has not been realized.

  As a method for producing a low-molecular-weight and high-quality polyarylene sulfide, at least polyarylene sulfide, oligoarylene sulfide obtained by contacting a sulfidizing agent and a dihalogenated aromatic compound in an organic polar solvent and reacting them, A method of recovering polyarylene sulfide from a reaction mixture containing an alkali metal halide and an organic polar solvent, wherein (a) the reaction mixture is subjected to a first solid-liquid separation at a temperature sufficient to dissolve the polyarylene sulfide in the reaction mixture. To obtain a filtrate component containing polyarylene sulfide, oligoarylene sulfide and an organic polar solvent. (B) Next, the filtrate component is brought to a temperature at which polyarylene sulfide does not dissolve, and then the filtrate component is separated into a second solid-liquid separation. Polyary characterized by processing Method for producing Nsurufido is disclosed (for example, Patent Document 9). In this method, the quality of PAS is improved by removing metal impurities and oligomer components by two types of solid-liquid separation, and low molecular weight PAS has also been successfully provided by selecting the conditions for PAS production. Yes. However, unlike the present invention, in the production of PAS, since the raw material dihalogenated aromatic compound is charged at a time, only PAS having a high halogen content could be produced.

  Moreover, in the manufacturing method of cyclic polyarylene sulfide represented by patent document 10 and 11, as a manufacturing method of the linear polyarylene sulfide used as the raw material, a sulfidizing agent and a dihalogenated aromatic compound are used as a sulfidizing agent. From a polyarylene sulfide mixture containing a cyclic polyarylene sulfide and a linear polyarylene sulfide obtained by heating and using an organic polar solvent of 1.25 liters or more per 1 mol of the sulfur component, It is disclosed to obtain linear polyarylene sulfides by separating the formula polyarylene sulfides. In these methods, since the sulfidizing agent and the dihalogenated aromatic compound are used in an amount of 1.25 liters or more of an organic polar solvent with respect to 1 mol of the sulfur component of the sulfidizing agent, the reproducibility is high. It is also possible to produce a PAS having a low molecular weight by a simple method. However, in these methods, unlike the present invention, since the raw material dihalogenated aromatic compound is charged at a time, only PAS having a high halogen content could be produced. Further, in these inventions, the production of cyclic PAS is aimed, and the PAS component is not described except for its use as a raw material, and there is no mention or suggestion regarding quality improvement.

  Similarly, Patent Document 12 discloses a method of preparing a dihalogenated aromatic compound as a raw material in two stages as a method for producing a cyclic polyarylene sulfide. This method is also intended to produce a cyclic PAS. For this reason, the PAS component is not described except for its use as a raw material, and there is no mention or suggestion regarding quality improvement. In this patent document, the reaction product obtained by the method for producing cyclic polyarylene sulfide is subjected to solid-liquid separation, and the PAS component is separated as wet PAS and used as a raw material for producing cyclic PAS. It is shown. However, this wet PAS component contains the organic polar solvent used in the reaction as a majority, and there is no mention of its characteristics, and there is no description of PAS isolated therefrom. .

Japanese Patent Publication No. 45-3368 JP-A-55-156342 JP 2009-203472 A JP 2011-126973 A JP-A-7-003022 JP 2010-53335 A International Publication No. 2010-010760 JP 2010-126621 A JP 2009-167395 A JP 2009-227592 A JP 2011-068885 A International Publication No. 2013-061561

  The present invention is a polyarylene sulfide and a method for producing the same, more specifically, a polyarylene sulfide resin that has been craved for high quality with reduced gas and chlorine contained during molding, and high fluidity during melt processing. It is an object of the present invention to provide a compatible polyarylene sulfide and a method for producing the same.

In order to solve the above problems, the present invention has the following configuration.
(1) A reaction mixture containing at least a sulfidizing agent (a), a dihalogenated aromatic compound (b) and an organic polar solvent (c), wherein 1.25 liters per 1 mol of sulfur component in the reaction mixture A method for producing polyarylene sulfide by heating and reacting the reaction mixture containing the organic polar solvent (c) of 50 liters or less, wherein reaction products obtained in the following Step 1 and Step 2 are used. And a polyarylene sulfide having a weight average molecular weight of 2,500 to 20,000 is isolated.
Step 1: heating the reaction mixture having an arylene unit of 0.80 mol or more and less than 1.05 mol per 1 mol of the sulfur component in the reaction mixture, so that the sulfiding agent (a) in the reaction mixture is heated. The process of making it react until 50% or more is consumed.
Step 2: After the step 1, after adding the dihalogenated aromatic compound (b) so that the arylene unit per mole of sulfur component in the reaction mixture is 1.05 mol or more and 1.50 mol or less A step of further heating to react to obtain a reaction product containing polyarylene sulfide.
(2) The method for producing polyarylene sulfide according to (1), wherein the following step 3 is performed after the step 2 to isolate the polyarylene sulfide from the solid content separated by solid-liquid separation.
Step 3: A step of subjecting the reaction product obtained in Step 2 to solid-liquid separation in a temperature range below the boiling point of the organic polar solvent (c) at normal pressure.
(3) Production of polyarylene sulfide according to (1) or (2), wherein the number of arylene units per mole of sulfur component in the reaction mixture in step 1 is 0.80 mol or more and less than 1.00 mol. Method.
(4) In the step 1, the reaction is performed until 70% or more of the sulfidizing agent (a) in the reaction mixture is reacted and consumed, and then the step 2 is performed. (1) to (3) A process for producing the polyarylene sulfide as described.
(5) A polyarylene sulfide having a weight average molecular weight of 2,500 to 20,000 and having a weight loss of 1.0% or less when heated at 320 ° C. for 2 hours under reduced pressure.
(6) The polyarylene sulfide according to (5), wherein the chlorine content is 5,000 ppm or less.
(7) The polyarylene sulfide according to (5) or (6), wherein the oligomer component content is 0.01% or more and 1.0% or less.
(8) The polyarylene sulfide according to any one of (5) to (7), which has a melt viscosity of 0.01 to 10 Pa · s.

  According to the present invention, it is possible to provide a polyarylene sulfide having high quality and extremely high fluidity during melt processing and a method for efficiently producing the same.

  Embodiments of the present invention will be described below.

(1) Sulfiding agent The sulfiding agent used in the present invention may be any sulfidizing agent as long as it can introduce a sulfide bond into a dihalogenated aromatic compound. Examples thereof include alkali metal sulfides, alkali metal hydrosulfides, and hydrogen sulfide. It is done.

  Specific examples of the alkali metal sulfide include lithium sulfide, sodium sulfide, potassium sulfide, rubidium sulfide, cesium sulfide and a mixture of two or more thereof, among which lithium sulfide and / or sodium sulfide are preferable. Sodium sulfide is more preferably used. These alkali metal sulfides can be used as hydrates or aqueous mixtures or in the form of anhydrides. The aqueous mixture refers to an aqueous solution, a mixture of an aqueous solution and a solid component, or a mixture of water and a solid component. Since generally available inexpensive alkali metal sulfides are hydrates or aqueous mixtures, it is 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 less than 1.05 mol. When hydrogen sulfide is used as the sulfiding agent, it is particularly preferable to use an alkali metal hydroxide at the same time. The amount of the alkali metal hydroxide used in this case is 2.0 to 3.0 with respect to 1 mole of hydrogen sulfide. Mol, preferably 2.01 to 2.50 mol, more preferably 2.04 to 2.40 mol, still more preferably 2.01 to 1.200 mol, and even more preferably 2.01 to 2.10 mol, Most preferably, the range is from 2.01 to less than 2.10 mol. By setting the amount of alkali metal hydroxide used in such a range, the nitrogen content contained in the obtained PAS tends to be further reduced, that is, the amount of impurity structures containing nitrogen atoms contained in the PAS can be reduced. There is a tendency to obtain a higher quality PAS. The reason for this is not clear, but side reactions caused by alkali metal hydroxides in the reaction for producing PAS are suppressed, so that nitrogen-containing byproducts are reduced and impurities containing nitrogen are introduced into PAS. It is speculated that it is easier to obtain PAS with higher purity because the reaction to be carried out is suppressed.

(2) Dihalogenated aromatic compound The dihalogenated aromatic compound used in the embodiment of the present invention is an aromatic compound having an arylene group which is a divalent group of an aromatic ring and two halogeno groups. One mole of the dihalogenated aromatic compound has 1 mole of an arylene unit and 2 moles of a halogeno group. For example, compounds having a phenylene group that is a divalent group of a benzene ring as an arylene group and two halogeno groups include p-dichlorobenzene, o-dichlorobenzene, m-dichlorobenzene, p-dibromobenzene, o-dibromo. Mention may be made of dihalogenated benzenes such as benzene, m-dibromobenzene, 1-bromo-4-chlorobenzene, and 1-bromo-3-chlorobenzene. Further, examples of the dihalogenated aromatic compound include 1-methoxy-2,5-dichlorobenzene, 1-methyl-2,5-dichlorobenzene, 1,4-dimethyl-2,5-dichlorobenzene, and 1,3-dimethyl. Mention may also be made of compounds containing substituents other than halogen, such as -2,5-dichlorobenzene and 3,5-dichlorobenzoic acid. Especially, the dihalogenated aromatic compound which has p-dihalogenated benzene represented by p-dichlorobenzene as a main component is preferable. Particularly preferably, it contains 80 to 100 mol%, more preferably 90 to 100 mol% of p-dichlorobenzene. It is also possible to use a combination of two or more different dihalogenated aromatic compounds in order to obtain a cyclic PAS copolymer.

(3) 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. However, the organic polar solvent is preferably an organic amide solvent. Specific examples include N-alkylpyrrolidones such as N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, and N-cyclohexyl-2-pyrrolidone, N-methyl-ε-caprolactam, and ε-caprolactam. Caprolactams, aprotic organic solvents represented by 1,3-dimethyl-2-imidazolidinone, N, N-dimethylacetamide, N, N-dimethylformamide, and hexamethylphosphoric triamide, and mixtures thereof Are preferably used because of high stability of the reaction. 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. It is 25 liters or more and 50 liters or less. The preferable lower limit of the amount of the organic polar solvent used is 1.5 liters or more, more preferably 2 liters or more. On the other hand, the upper limit is preferably 20 liters or less, and more preferably 15 liters or less. Here, the amount of solvent used is based on the volume of the solvent under normal temperature and pressure.

  When the amount of the organic polar solvent used per mole of sulfur component is less than 1.25 liters, polyarylene sulfide having a high molecular weight tends to be generated, and the fluidity in the melt processing of the finally isolated PAS is low. It tends to decrease. Further, it is presumed that the generation probability of impurity oligomers and the generation probability of impurity-type ends due to side reactions is increased, and the amount of gas components generated during the melt processing of the finally obtained PAS tends to increase. Here, since the molecular weight of PAS tends to decrease as the amount of the organic polar solvent used increases, it is necessary to use a larger amount of inspiratory polar solvent from the viewpoint of obtaining a more fluid PAS. preferable. However, from the viewpoint of efficiently recovering PAS in the PAS isolation operation, the weight average molecular weight of PAS needs to be 2,500 or more, and in order to achieve this molecular weight lower limit, it is less than the upper limit of the amount of organic polar solvent used. It is necessary to If the amount of the organic polar solvent used is extremely increased, the amount of PAS produced per unit volume of the reaction vessel tends to decrease, and the time required for the reaction tends to increase. Therefore, it is preferable to set the amount of the organic polar solvent used in the above range from the viewpoint of achieving both the quality, recovery efficiency, and productivity of polyarylene sulfide.

  In general PAS production, the amount of the solvent used is often very small because the purpose is to proceed with the polymerization reaction, and the polymerization reaction is difficult to proceed within the preferred amount range of the embodiment of the present invention. It was thought that only a low PAS component could be obtained. In the embodiment of the present invention, PAS can be obtained efficiently even under conditions where the amount of solvent used is large compared to the case of general PAS production. The reason for this is not clear at this time, but it is presumed that the solvent use amount range of the present invention has a high reaction efficiency and a high consumption rate of the raw material, which preferably acts on the production of PAS.

  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.

(4) Polyarylene sulfide The polyarylene sulfide in the present invention is a homopolymer or copolymer having a repeating unit of formula, — (Ar—S) —, as the main constituent unit, preferably containing 80 mol% or more of the repeating unit. Thus, the structure is preferably linear. Ar includes units represented by the following formulas (A) to (L), among which the formula (A) is particularly preferable.

(In the formula, R1 and R2 are substituents selected from hydrogen, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, and a halogen group, and R1 and R2 are the same or different. May be.)

  As long as this repeating unit is a main structural unit, it can contain a small amount of branching units or crosslinking units represented by the following formulas (M) to (P). 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 PAS in the present invention may be any of a random copolymer, a block copolymer and a mixture thereof containing the above repeating unit. Typical examples of these include polyphenylene sulfide, polyphenylene sulfide sulfone, polyphenylene sulfide ketone, random copolymers thereof, block copolymers, and mixtures thereof. Particularly preferred PASs include p-phenylene sulfide units as the main structural unit of the polymer.

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

  The melt viscosity of PAS in the present invention is not particularly limited, but according to the method of the present invention, a PAS having a low melt viscosity and excellent fluidity tends to be obtained. Specifically, the melt viscosity at 300 ° C. can be exemplified as a range of 0.01 to 10 Pa · s, and a highly fluid PAS of 0.05 to 7 Pa · s, particularly preferably 0.1 to 5 Pa · s is preferable. It tends to be obtained. Here, the melt viscosity of PAS can be measured by a dynamic viscoelasticity measuring method, for example, a rotary type motion having a parallel disk type (diameter 25 mm) and a geometry having a cup (inner diameter about 28 mm) on a lower plate. This is the viscosity at 300 ° C. when the temperature is increased from 100 ° C. to 320 ° C. at 5 ° C./min under a nitrogen stream with an angular frequency of 3.1 / second using a mechanical viscoelasticity measuring device (rheometer). In addition, the melt viscosity of a general PAS obtained by the conventional production method is several hundred Pa · s, and the PAS of the present invention has a significantly lower viscosity and excellent fluidity than the PAS of the conventional production method. It is also known that PAS of several tens of Pa · s can be obtained by setting special manufacturing conditions in the conventional manufacturing method. In this case, however, there is a problem that the gas generated at the time of melting described later increases remarkably. It was not an industrially applicable PAS. On the other hand, in the conventional PAS manufacturing method, as a method for reducing the amount of gas generated at the time of melting, a method (curing) for heat treatment in an oxidizing atmosphere is known. Since a marked increase in melt viscosity proceeds, there is a problem that only a PAS having a melt viscosity higher than that of the PAS of the present invention can be obtained.

  In the present invention, a PAS having a low molecular weight tends to be easily obtained. The molecular weight is 2,500 to 20,000 in terms of weight average molecular weight, preferably 5,000 to 18,000, and preferably 5,000 to 16,000. Is more preferable. In general, a PAS having a weight average molecular weight in the above range can achieve both the expression of extremely high fluidity and the expression of properties such as mechanical strength and chemical resistance. Also, under the conditions for performing the separation operation of PAS and oligoarylene sulfide, which will be described later, such a PAS tends to exist as a solid in an organic polar solvent, so that the separation property from oligoarylene sulfide tends to be remarkably improved. Therefore, it can be said to be particularly suitable in the present invention.

  The PAS of the present invention is superior in quality as compared with the conventional PAS, and has the characteristics that the gas generated at the time of melting is small and the amount of chlorine contained is particularly important as the characteristics of the PAS.

  Here, the feature that the gas generated at the time of melting is small can be evaluated by comparing the weight reduction rate ΔW (%) before and after heating. Here, ΔW can be expressed as a weight reduction rate when heated at 320 ° C. for 2 hours under reduced pressure conditions.

As a specific method for measuring ΔW, 3 g of a polymer is measured in a glass ampoule having an abdomen of 100 mm × 25 mmφ, a neck of 255 mm × 12 mmφ, and a wall thickness of 1 mm, and vacuum sealed. The ampule is taken out after being inserted into an electric tubular furnace and heated at 320 ° C. for 2 hours, and the ampule neck which has not been heated by the tubular furnace and is attached with volatile gas is cut out with a file and weighed. After dissolution and removal, the sample is dried for 1 hour in a glass dryer at 60 ° C. and then weighed again, and the weight difference between the neck of the ampoule before and after removing the gas component can be measured as the amount of volatile components (% by weight relative to the polymer). .
Here, in the PAS of the present invention, ΔW is 1.0% or less, preferably 0.8% or less, more preferably 0.6% or less, and 0.5% or less. Even more preferable. When ΔW exceeds the above range, for example, there is a tendency that the amount of generated gas is large when PAS is molded, and it tends to occur, which is not preferable. Also, a die or 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.

  In general, the weight loss during heating of the polymer material including the polyarylene sulfide which is the subject of the present invention tends to increase as the molecular weight decreases. There are various reasons for this, but the lower the molecular weight of the polymer, the higher the terminal amount of the polymer. Generally, the terminal is inferior in thermal stability compared to the normal main chain structure. The amount of generated gas is thought to increase. For example, in the case of polyarylene sulfide, the usual main chain structure is an arylene sulfide unit. On the other hand, a halogeno group end or a thiol group end, which is a general terminal structure of polyarylene sulfide, is unstable compared to the main chain structure because its electronic state is different from the main chain structure. Therefore, it is presumed that an unstable terminal structure becomes a starting point for initiation of thermal decomposition when heated, and it is considered that the weight loss amount upon heating increases as the terminal amount increases, that is, as the molecular weight is low.

  As described above, the molecular weight of the PAS of the present invention is 2,500 to 20,000 in terms of weight average molecular weight, and the molecular weight of general PAS products on the market, that is, about 20,000 to 100,000. Lower molecular weight. It is known that a low molecular weight PAS having the same level as that of the PAS of the present invention, that is, a molecular weight of about 10,000 can be produced even in the prior art. However, the low molecular weight PAS of the prior art is, as far as the present inventors know, the weight loss ΔW when heated greatly exceeds 1.0%, so it is difficult to reduce the low molecular weight and the generated gas during heating. there were. Unlike these conventional techniques, PAS obtained by the preferred production method of the present invention is extremely high in purity, and therefore it is presumed that both a reduction in ΔW value and a low molecular weight can be achieved.

  The PAS of the present invention preferably contains substantially no halogen other than chlorine, that is, fluorine, bromine, iodine, or astatine. When the PAS of the present invention contains chlorine as a halogen, it is stable in the temperature range where PAS is usually used. Therefore, even if a small amount of chlorine is contained, there is little influence on the mechanical properties of the PAS. When contained, these unique properties tend to deteriorate the properties of PAS, such as electrical properties and residence stability.

  When the PAS of the present invention contains chlorine as a halogen, the preferred upper limit is 5,000 ppm or less, more preferably 3,500 ppm or less, still more preferably 2,500 ppm or less, and even more preferably 2,000 ppm or less. On the other hand, the preferred lower limit is 100 ppm or more, more preferably 300 ppm or more, and even more preferably 500 ppm or more. Within this range, the electrical properties and residence stability of PAS tend to be better.

  As described above, it is presumed that halogens contained in PAS, specifically chlorine, etc. exist as terminal structures of PAS. Here, the amount of chlorine in the conventional PAS, which is a PAS according to the prior art and has the same molecular weight as that of the PAS of the present invention, is significantly larger than the amount of chlorine of the PAS of the present invention described above. Unlike these conventional techniques, PAS obtained by the preferred production method of the present invention is extremely high in purity, and therefore, it is assumed that a low chlorine content and a low molecular weight are compatible.

  As described above, the PAS of the present invention has a feature that the generated gas at the time of melting is less than that of the conventional PAS, but at the same time, it has a feature that the nitrogen content is also low. Here, the commercially available PAS generally shows a nitrogen content of several hundred to several thousand ppm, and in particular, a low molecular weight product having a molecular weight of 20,000 or less generally shows a nitrogen content of 1000 ppm or more. Conventional high purity and high molecular weight PAS generally exceeds 800 ppm. On the other hand, the PAS of the present invention adopts a nitrogen content of less than 1000 ppm, preferably 800 ppm or less, even though the molecular weight is 20,000 or less, preferably 500 ppm or less by adopting the preferred conditions of the present invention. By doing so, it becomes possible to realize 400 ppm or less. Here, there is no lower limit of the nitrogen content, and it is preferable that the nitrogen content is low. However, if specific numerical values are exemplified, the lower limit value of the nitrogen content is usually about 1 ppm. In PAS, since the nitrogen-containing structure is a defect structure different from the polymer structural unit, the smaller the nitrogen content, for example, the better the retention stability and the better the workability, and the change in mechanical properties after melt processing is Extremely small and easy to maintain high quality. Although the reason for this is not clear at present, it is presumed that the nitrogen-containing compound promotes oxidative crosslinking, but the oxidative crosslinking is suppressed by reducing the amount of the nitrogen-containing compound.

  Here, the nitrogen content in the present invention refers to the total nitrogen content contained in the sample. The nitrogen content can be evaluated by elemental nitrogen analysis. For example, the sample is pyrolyzed and oxidized at a final temperature of 900 ° C. using a horizontal reactor, and the generated nitrogen monoxide is supplied to a nitrogen detector and obtained. it can.

(5) Oligoarylene sulfide The oligoarylene sulfide in the present invention is a homopolymer or copolymer having a repeating unit of the formula:-(Ar-S)-as the main constituent unit, preferably containing 80 mol% or more of the repeating unit. . Ar includes units represented by the above formulas (A) to (L), among which the formula (A) is particularly preferable.

  In addition, the oligoarylene sulfide in the present invention may be any of a random copolymer, a block copolymer and a mixture thereof containing the repeating unit. Typical examples of these include oligophenylene sulfide, oligophenylene sulfide sulfone, oligophenylene sulfide ketone, random copolymers thereof, block copolymers, and mixtures thereof. Particularly preferred oligoarylene sulfides include oligopolyphenylene sulfide sulfones and oligophenylene sulfide ketones in addition to oligophenylene sulfides containing 80 mol% or more, particularly 90 mol% or more of p-phenylene sulfide units as main structural units.

  The average molecular weight of various oligoarylene sulfides in the present invention can be defined as lower than the above-mentioned PAS, and the weight average molecular weight of a general oligoarylene sulfide can be exemplified by 200 to 5,000, preferably 200 to 2,500. 300 to 2,000 is more preferable. As a result of detailed examination of the difference in properties between PAS and oligoarylene sulfide, the inventors of the present invention have a tendency for oligoarylene sulfide having a weight average molecular weight in the above-mentioned range to be more soluble in various solvents than the aforementioned PAS. I found out. In particular, it has been found that oligoarylene sulfide has high solubility in an organic polar solvent, and in this respect, the characteristics are greatly different from those of the aforementioned PAS. That is, PAS is likely to be present as a solid in an organic polar solvent under the conditions for separating PAS and oligoarylene sulfide, which will be described later. On the other hand, oligoarylene sulfide is easily dissolved in an organic polar solvent. The present inventors have found that PAS and oligoarylene sulfide can be separated with good separability by liquid separation operation, and the present invention has been completed. From this viewpoint, in the present invention, it can be said that the above range is particularly suitable for the weight molecular weight of the oligoarylene sulfide.

  Moreover, there is no restriction | limiting in particular in the structure of the oligoarylene sulfide of this invention, Various structures, such as a linear structure, a branched structure, a graft structure, and a cyclic structure, and mixtures thereof are accept | permitted. Among these, linear and / or cyclic oligoarylene sulfides are preferable, and there is an advantage that a strict reaction control and a third component for introducing a branched structure are not required to obtain these structures.

  Herein, the oligoarylene sulfide cyclic body in the present invention (hereinafter sometimes referred to as a cyclic oligoarylene sulfide) is a cyclic compound having a repeating unit of formula, — (Ar—S) — as a main structural unit. Preferably, it is a compound such as the following general formula (Q) containing 80 mol% or more of the repeating unit.

  Here, examples of Ar can include units represented by the formulas (A) to (L), among which the formulas (A) to (C) are preferable, and the formulas (A) and (B) are more preferable. Formula (A) is particularly preferable.

  In addition, in cyclic oligoarylene sulfide, repeating units, such as said Formula (A)-Formula (L), may be included at random, may be included in a block, and any of those mixtures may be sufficient. Typical examples of these include cyclic oligophenylene sulfide, cyclic oligophenylene sulfide sulfone, cyclic oligophenylene sulfide ketone, cyclic random copolymers containing these, cyclic block copolymers, and mixtures thereof. Is mentioned. Particularly preferred cyclic oligoarylene sulfides include cyclic oligophenylene sulfides (hereinafter sometimes abbreviated as cyclic PPS) containing 80 mol% or more, particularly 90 mol% or more of p-phenylene sulfide units as main structural units. Can be mentioned.

  Although there is no restriction | limiting in particular in the repeating number m in the said (Q) formula of cyclic oligoarylene sulfide, 2-50 are preferable, 2-25 are more preferable, and 3-20 can be illustrated as a still more preferable range. The use of cyclic oligoarylene sulfide can be exemplified by the use of a mixture containing cyclic oligoarylene sulfide that is converted to a high degree of polymerization by heating, and when used in such applications, cyclic oligoarylene sulfide is used. It is preferable to carry out the heating at a temperature higher than the temperature at which the sulfide melts, but when m increases, the melting temperature of the cyclic oligoarylene sulfide tends to increase. Therefore, when cyclic oligoarylene sulfide is used for such applications, it is advantageous to set m in the above range from the viewpoint that the melt solution of cyclic oligoarylene sulfide is possible at a lower temperature.

  The cyclic oligoarylene sulfide may be either a single compound having a single repeating number or a mixture of cyclic oligoarylene sulfides having different repeating numbers, but it may be a mixture of cyclic oligoarylene sulfides having different repeating numbers. The melt solution temperature tends to be lower than that of a single compound having a single number of repetitions, and the use of a mixture of cyclic oligoarylene sulfides having different numbers of repetitions is used in the conversion to the above-mentioned high degree of polymerization. This is preferable because the temperature can be lowered.

(6) Method for Producing Polyarylene Sulfide In an embodiment of the present invention, a reaction mixture containing at least a sulfidizing agent (a), a dihalogenated aromatic compound (b) and an organic polar solvent (c), wherein the reaction A method for producing polyarylene sulfide by heating and reacting the reaction mixture containing 1.25 liters to 50 liters of the organic polar solvent (c) with respect to 1 mol of a sulfur component in the mixture, It is characterized by isolating polyarylene sulfide from the reaction product obtained by including the following Step 1 and Step 2, thereby having excellent characteristics as shown in the above section (4). It is possible to produce polyarylene sulfides.
Step 1: heating the reaction mixture having an arylene unit of 0.80 mol or more and less than 1.05 mol per 1 mol of the sulfur component in the reaction mixture, so that the sulfiding agent (a) in the reaction mixture is heated. The process of making it react until 50% or more is consumed.
Step 2: After the step 1, after adding the dihalogenated aromatic compound (b) so that the arylene unit per mole of sulfur component in the reaction mixture is 1.05 mol or more and 1.50 mol or less A step of further heating to react to obtain a reaction product containing polyarylene sulfide.

  Hereinafter, step 1 and step 2 will be described in detail.

(7) Production of polyarylene sulfide; Step 1
In the embodiment of the present invention, the reaction mixture containing the raw material components is used in Step 1. In step 1, at least the sulfidizing agent and the dihalogenated aromatic compound contained in the reaction mixture react with each other, so that the production of polyarylene sulfide as the target product proceeds.

  Here, in the reaction mixture used in Step 1, the number of arylene units per mol of sulfur component in the reaction mixture is 0.80 mol or more and less than 1.05 mol. The lower limit of the arylene unit is preferably 0.82 mol, more preferably 0.87 mol, still more preferably 0.90 mol, even more preferably 0.92 mol, and even more preferably 0.94 mol. The upper limit of the arylene unit is preferably 1.02 mol, more preferably 1.005 mol, further preferably less than 1.00 mol, even more preferably 0.995 mol, and even more preferably 0.990 mol. .

  As the lower limit value of the arylene unit per mole of the sulfur component in the reaction mixture is selected, the lower the lower limit value, the easier it is to obtain polyarylene sulfide having a lower chlorine content. Moreover, it exists in the tendency which can reduce the production amount of the impurity in manufacture of a polyarylene sulfide, so that a higher lower limit is selected. In particular, when the lower limit value of less than 0.94 mol is selected, the chlorine content of polyarylene sulfide is particularly likely to be reduced, while when the lower limit value of 0.94 mol or more is selected, the formation of impurities There is a strong tendency to significantly suppress.

  Here, in step 1, an arylene sulfide unit is sequentially formed by reacting a sulfidizing agent and a dihalogenated aromatic compound in the reaction mixture to produce polyarylene sulfide. Here, when the dihalogenated aromatic compound is excessive with respect to the sulfidizing agent, that is, the higher the ratio of the arylene units per mole of the sulfur component in the reaction mixture, the easier the polyarylene sulfide having a halogeno group at the terminal is formed. . Conversely, when the dihalogenated aromatic compound is insufficient with respect to the sulfidizing agent, that is, when the ratio of arylene units per mole of sulfur component in the reaction mixture is low, a polyarylene sulfide having a sulfide at its end is formed. It becomes a trend.

  Here, the latter, that is, when the dihalogenated aromatic compound is insufficient relative to the sulfidizing agent, the polyarylene sulfide to be produced tends to have fewer terminal halogeno groups, but when the dihalogenated aromatic compound is insufficient. , The molecular weight of the produced PAS is extremely lowered, and the stability of the PAS during melt processing tends to be lowered. From the relationship of the molar ratio of the dihalogenated aromatic compound to the sulfidizing agent, it is possible to achieve both the reduction of the chlorine content of the polyarylene sulfide and the reduction of the oligomer amount by adopting the lower limit value described above.

  As mentioned above, in the embodiment of the present invention, the arylene sulfide compound is produced by reacting the sulfidizing agent (a) with the dihalogenated aromatic compound (b). Therefore, as the reaction proceeds, an arylene sulfide unit corresponding to the amount of the dihalogenated aromatic compound consumed is newly generated. That is, when the arylene-containing component is not removed or added to the reaction mixture during the reaction, it can be said that the amount of arylene units in the reaction mixture is the same as that in the preparation stage even at the stage where the reaction has progressed.

  The arylene unit contained in the reaction mixture means that the raw material containing the arylene unit is dihalogenated at the stage where the reaction between the sulfidizing agent (a) charged as a raw material and the dihalogenated aromatic compound (b) has not progressed at all. In the case of only the aromatic compound (b), it means an arylene unit derived from the dihalogenated aromatic compound (b) contained in the reaction mixture.

  The amount of the arylene unit in the reaction mixture can also be determined by quantifying the amount of the arylene unit derived from the dihalogenated aromatic and the amount of the arylene sulfide compound present in the reaction system. Here, the amount of the dihalogenated aromatic compound in the reaction mixture can be determined by a method using a gas chromatographic method described later. In addition, the amount of the arylene sulfide compound in the reaction mixture is determined by determining the amount of solid content obtained by dispersing a part of the reaction mixture in a large excess of water, recovering insoluble components in water, and drying the recovered components. It can be obtained by measuring.

  Moreover, the molar amount of the sulfur component contained in the reaction mixture is synonymous with the molar amount of sulfur atoms present in the reaction mixture. For example, when 1 mole of alkali metal sulfide is present in the reaction mixture and no other component containing sulfur is present, the sulfur component contained in the reaction mixture corresponds to 1 mole. Further, when 0.5 mole of alkali metal hydrosulfide and 0.5 mole of arylene sulfide unit are present in the reaction mixture, the sulfur component contained in the reaction mixture corresponds to 1 mole.

  Therefore, when the reaction of the sulfidizing agent (a) and the dihalogenated aromatic compound (b) charged as raw materials is not progressing at all, when the raw material having sulfur atoms is only the sulfidizing agent (a), The molar amount of the sulfur component contained in the reaction mixture refers to the molar amount of the sulfur component derived from the sulfidizing agent (a). In the case where polyarylene sulfide is contained in the stage where the reaction has progressed or in the raw material, that is, the reaction initiation stage, the molar amount of the sulfur component contained in the reaction mixture is the sulfur derived from the sulfidizing agent contained in the reaction mixture. The total molar amount of the component and the sulfur component derived from the arylene sulfide compound present in the reaction system.

  Here, as described above, in the embodiment of the present invention, the arylene sulfide compound is produced by the reaction between the sulfidizing agent (a) and the dihalogenated aromatic compound (b). Arylene sulfide units corresponding to the amount of the sulfidizing agent thus formed are newly generated. That is, if there is no removal, loss or addition of the sulfidizing agent in the reaction mixture during the reaction, it can be said that the amount of sulfur component contained in the reaction mixture is the same as in the preparation stage even at the stage where the reaction has progressed.

  Further, the amount of the sulfur component in the reaction mixture can be determined by quantifying the amount of the sulfur component derived from the sulfidizing agent and the amount of the arylene sulfide compound present in the reaction system. Here, the amount of the sulfidizing agent in the reaction mixture can be determined by an ion chromatography method described later. The method for quantifying the arylene sulfide compound in the reaction mixture is as described above.

  Here, in the embodiment of the present invention, the condition that the arylene unit relative to the sulfur component is preferably set such that the number of arylene units per mol of the sulfur component in the reaction mixture in Step 1 is 0.80 mol or more and less than 1.00 mol is preferably set. It is possible. Conventionally, in such a range, there has been a problem that it is difficult to obtain the target product, and as described later in detail, the separability when performing solid-liquid separation when recovering polyarylene sulfide is reduced. However, the embodiment of the present invention is characterized in that the step 2 is performed subsequent to the step 1, so that the target product can be obtained without any problem even if the reaction is performed in such a range, and the quality of the polyarylene sulfide is also improved. As a result, the present invention has been completed.

  In step 1, the reaction mixture having the above composition is heated to perform the reaction. The temperature in this reaction is preferably a temperature exceeding the reflux temperature of the reaction mixture under normal pressure. This desirable temperature cannot be uniquely determined because it varies depending on the kind and amount of the sulfidizing agent, dihalogenated aromatic compound and organic polar solvent used in the reaction, but is usually 120 ° C or higher, preferably 180 ° C or higher. Preferably it is 220 degreeC or more, More preferably, it can be 225 degreeC or more. Moreover, it can be 350 degrees C or less, Preferably it is 320 degrees C or less, More preferably, it is 310 degrees C or less, More preferably, it can be 300 degrees C or less.

  Within this preferred temperature range, the substantial reaction consumption of the sulfidizing agent (a) and the dihalogenated aromatic compound (b) proceeds rapidly to produce polyarylene sulfide, and the reaction tends to proceed in a short time. Here, the normal pressure is a pressure in the vicinity of the standard state of the atmosphere, and the standard state of the atmosphere is an atmospheric pressure condition in which the temperature is about 25 ° C. and the absolute pressure is about 101 kPa. The reflux temperature is the temperature at which the liquid component of the reaction mixture repeats boiling and condensation. In the embodiments of the present invention, it has been described above that it is desirable to heat the reaction mixture beyond the reflux temperature under normal pressure. However, as a method for bringing the reaction mixture into such a heated state, for example, the reaction mixture is heated to normal pressure. Examples thereof include a method of reacting under a pressure exceeding the pressure and a method of heating the reaction mixture in a closed container. The reaction may be either a one-step reaction performed at a constant temperature, a multi-stage reaction in which the temperature is raised stepwise, or a reaction in which the temperature is continuously changed.

  The reaction time in Step 1 depends on the type and amount of the raw material used or the reaction temperature, and thus cannot be defined unconditionally, but is preferably 0.1 hours or longer, more preferably 0.5 hours or longer. Here, as described later, when performing step 2 after step 1, it is preferable to perform step 2 after sufficiently consuming the sulfidizing agent and dihalogenated aromatic compound in the reaction mixture in step 1. By setting the above-mentioned preferable reaction time, these raw material components tend to be sufficiently consumed by reaction. On the other hand, the reaction time is not particularly limited, but the reaction proceeds sufficiently even within 40 hours, preferably within 10 hours, more preferably within 6 hours.

  The pressure in step 1 is not particularly limited, and the pressure varies depending on the raw materials constituting the reaction mixture, the composition thereof, the reaction temperature, etc., and thus cannot be uniquely defined. An example is 0.05 MPa or more, more preferably 0.3 MPa or more. In addition, since the pressure rise by the self-pressure of the reactant occurs at the preferable reaction temperature of the embodiment of the present invention, the lower limit of the preferable pressure at such a reaction temperature is 0.25 MPa or more, more preferably 0. 3 MPa or more can be illustrated. Moreover, as a preferable upper limit of pressure, 10 MPa or less, More preferably, 5 MPa or less can be illustrated.

  In such a preferable pressure range, the time required for bringing the sulfidizing agent and the dihalogenated aromatic compound into contact with each other tends to be shortened. Further, in order to set the pressure at the time of heating the reaction mixture to the above preferable pressure range, the reaction mixture is reacted with an inert gas described later at an optional stage such as before starting the reaction or during the reaction, preferably before starting the reaction. It is also a preferable method to pressurize the system. Here, the gauge pressure is a relative pressure based on the atmospheric pressure, and is equivalent to a pressure difference obtained by subtracting the atmospheric pressure from the absolute pressure.

  In addition to the essential components, a third component that does not significantly inhibit the reaction and a third component that has an effect of accelerating the reaction can be added to the reaction mixture. Although there is no restriction | limiting in particular in the method of performing reaction, It is preferable to carry out on stirring conditions. In addition, there is no restriction | limiting in particular in the temperature at the time of charging a raw material here, For example, you may react after charging a raw material near room temperature, or charge a raw material to the reaction container temperature-controlled beforehand to the temperature preferable for reaction mentioned above. It is also possible to carry out the reaction. It is also possible to continuously carry out the reaction by sequentially charging the raw material into the reaction system in which the reaction is performed.

  Further, as the sulfidizing agent (a), the dihalogenated aromatic compound (b), and the organic polar solvent (c), those containing water can be used. However, the amount of water at the start of the reaction, that is, at the stage where the substantial reaction consumption of the sulfidizing agent (a) and the dihalogenated aromatic compound (b) charged as a reaction mixture has not progressed is the sulfur component in the reaction mixture. The amount is preferably 0.2 mol or more, more preferably 0.5 mol or more, and further preferably 0.6 mol or more per mol. The water content is preferably 20.0 mol or less, more preferably 10.0 mol or less, and more preferably 8.0 mol or less per mol of sulfur component in the reaction mixture. preferable. When the sulfidizing agent, organic polar solvent, dihalogenated aromatic compound, and other components that form the reaction mixture contain water, and the amount of water in the reaction mixture exceeds the above range, In the middle of the reaction, an operation of reducing the amount of water in the reaction system can be performed to make the amount of water within the above range, whereby the reaction tends to proceed efficiently in a short time. In addition, when the water content of the reaction mixture is less than the above preferable range, it is also a preferable method to add water so that the water content becomes the above water content.

  When the amount of water in the reaction system is within the above preferred range (0.2 to 20.0 moles per mole of sulfur component in the reaction mixture), the reaction efficiency of the sulfiding agent and dihalogenated aromatic compound as raw materials is high. The polyarylene sulfide tends to be obtained efficiently in a short time. Further, the high reaction efficiency of the raw material brings about the effect of relatively suppressing the side reaction that progresses competitively with the polyarylene sulfide formation reaction, that is, the object of the embodiment of the present invention, that is, the impurity formation reaction. It can be estimated that the polyarylene sulfide having a low impurity ratio and excellent quality is obtained by carrying out the reaction with a preferable water content.

Here, the reaction consumption rate of the dihalogenated aromatic compound is a value calculated by the following equation. The residual amount of the dihalogenated aromatic compound can be usually determined by gas chromatography.
When the dihalogenated aromatic compound is added excessively in a molar ratio with respect to the sulfidizing agent, the reaction consumption rate (%) = [[the charged amount of dihalogenated aromatic compound (mol) −the remaining amount of dihalogenated aromatic compound ( Mol)) / [charge amount of dihalogenated aromatic compound (mol) -excess amount of dihalogenated aromatic compound (mol)]] × 100
When the dihalogenated aromatic compound is added in a molar ratio relative to the sulfidizing agent, the reaction consumption rate (%) = [[the charged amount of dihalogenated aromatic compound (mol) −the remaining amount of dihalogenated aromatic compound ( Mol)] / [amount of dihalogenated aromatic compound (mol)]] × 100
(8) Production of polyarylene sulfide; Step 2
In Step 2, after Step 1, the dihalogenated aromatic compound (b) is added and heated further so that the number of arylene units per mole of sulfur component in the reaction mixture is 1.05 mol or more and 1.50 mol or less. To obtain a reaction product containing polyarylene sulfide.

  The additional amount of the dihalogenated aromatic compound in the step 2 is such that the total amount of the arylene units in the reaction mixture in the step 1 and the arylene units derived from the newly added dihalogenated aromatic compound is 1 mol of the sulfur component in the reaction mixture. The amount of the arylene unit per unit is in the range of 1.05 mol or more and 1.50 mol or less. Here, the lower limit of the total amount of the arylene units after addition of the dihalogenated aromatic compound is 1.05 mol per mol of the sulfur component in the reaction mixture, and preferably 1.06 mol. The upper limit is 1.50 mol, preferably 1.30 mol, more preferably 1.20 mol, even more preferably 1.15 mol, and still more preferably 1.12 mol. By performing the reaction in step 2 with the total amount of the arylene units in such a range, not only the separation property in the solid-liquid separation operation is significantly improved, but also the recovery is performed when the polyarylene sulfide is isolated and recovered as described later. The resulting polyarylene sulfide has an extremely high quality. On the other hand, when the additional amount of the dihalogenated aromatic compound is less than the above range, the separability when performing solid-liquid separation to recover the polyarylene sulfide is lowered. On the other hand, when the above range is exceeded, high separability tends to be obtained at the time of solid-liquid separation, but the residual amount of unreacted dihalogenated aromatic compound increases, and such a residue A separate facility is required to recover the wastewater, and the operation becomes complicated. In addition, there is a disadvantage that the cost required for collection increases.

  Although there is no restriction | limiting in particular in the method of adding said dihalogenated aromatic compound, For example, the method of performing intermittently several times, the method of performing continuously at a fixed speed etc. can be illustrated. Here, as described in detail in the description of Step 1, the amount of arylene units per mole of sulfur component in the reaction mixture used in Step 1 is set to a condition where the number of arylene units is insufficient with respect to the sulfur component. It is effective from the viewpoint of improving quality, such as reducing the chlorine content of polyarylene sulfide. When such a condition is adopted, when adding the dihalogenated aromatic compound in step 2, the addition is performed intermittently over a plurality of times and / or continuously at a constant rate. It is desirable. In particular, when the arylene unit per mole of sulfur component in the reaction mixture is closer to the lower limit within the above-mentioned preferred range, the method of intermittently adding the dihalogenated aromatic compound in step 2 and / or The method of continuously performing at a constant rate is effective for reducing the impurity component contained in the obtained polyarylene sulfide and obtaining a higher-quality polyarylene sulfide.

  Here, in the case where the dihalogenated aromatic compound is intermittently added several times after the step 1 is performed under the condition that the amount of the arylene unit relative to the sulfur component is insufficient, first, the sulfur in the reaction mixture is first temporarily removed. After adding the dihalogenated aromatic compound so that the amount of the arylene unit per 1 mol of the component is about 1.00 mol, the amount of the arylene unit per mol of the sulfur component in the reaction mixture is the predetermined value of step 2. A method of further adding is preferable. When intermittent addition is performed by such a method, it is possible to reduce the amount of impurities generated.

  As a specific method for adding the dihalogenated aromatic compound into the reaction system, a predetermined amount of the dihalogenated aromatic compound is introduced into the reaction system through a pressure-resistant addition pot, or a molten dihalogenated aromatic compound is used. Examples thereof include a method in which a dihalogenated aromatic compound in solution using an aromatic compound or an organic polar solvent is pressed into the reaction system by a pressure pump.

  Here, it is desirable to add the dihalogenated aromatic compound after the sulfidizing agent (a) in the reaction mixture has been sufficiently consumed. Specifically, the addition of the dihalogenated aromatic compound is performed after the reaction until 50% or more of the sulfidizing agent is consumed as a lower limit, and after the reaction until 60% or more is consumed. More preferably, it is carried out after reacting until 70% or more of the reaction is consumed, more preferably after reacting until 80% or more of the reaction is consumed, and reaction is carried out until 90% or more of the reaction is consumed. It is particularly preferred to do this later. It is extremely important to add the dihalogenated aromatic compound after the reaction consumption of the sulfidizing agent is advanced to the above range in order to suppress the formation of impurity components and improve the quality of the resulting polyarylene sulfide. It is. When the degree of reaction consumption of the sulfiding agent is less than 50%, the amount of impurity components in the reaction product obtained after the reaction increases. Such an increase in the amount of impurity components must be avoided even in the case where polyarylene sulfide is recovered and isolated because it directly leads to an increase in the content of impurities contained in the isolated polyarylene sulfide.

  Here, in the method according to the embodiment of the present invention, the reaction consumption rate of the sulfidizing agent is, for example, the sulfide remaining in the reaction mixture using an ion chromatography technique equipped with an electrical conductivity detector or an electrochemical detector. It can be calculated by quantifying the amount of the agent. In this case, as a ratio of the reaction consumption of the sulfidizing agent (a value obtained by subtracting the residual amount of the sulfidizing agent in the reaction mixture from the amount of the sulfidizing agent charged) to the amount of the sulfidizing agent charged, sulfidation The reaction consumption rate of the agent can be calculated. As a specific evaluation method using ion chromatography, hydrogen peroxide solution is added to the sample to oxidize sulfide ions contained in the sample, and then analysis using an electrical conductivity detector Thus, a method of calculating the amount of sulfate ions generated by oxidation of sulfide ions can be exemplified. It is possible to quantify the remaining amount of the sulfidizing agent from the amount of sulfate ions and calculate the reaction consumption rate of the sulfidizing agent.

  In Step 2, the reaction is further carried out after adding the dihalogenated aromatic compound, and it is possible to adopt the preferable conditions in Step 1 described in the preceding paragraph (7) for various conditions such as temperature, pressure and water content in this reaction. It is.

  Specifically, the reaction temperature in step 2 is preferably a temperature exceeding the reflux temperature of the reaction mixture under normal pressure. In Step 2, a temperature higher than the temperature used in Step 1 can also be adopted, specifically 180 ° C. or higher, more preferably 220 ° C. or higher, and further preferably 225. It can be set to 260 ° C. or higher, more preferably 250 ° C. or higher. Moreover, the temperature of the process 2 can be 320 degrees C or less, More preferably, it is 310 degrees C or less, More preferably, it can be 300 degrees C or less. In this preferable temperature range, not only the reaction tends to proceed in a short time, but also when the temperature higher than that in Step 1 is adopted, the amount of impurity components also tends to be reduced.

  Since the reaction time in Step 2 depends on the type and amount of raw materials used or the reaction temperature, it cannot be specified unconditionally. However, since most of the sulfidizing agent charged in Step 1 has already been consumed, the reaction time in Step 1 It is possible to allow a sufficient reaction to proceed even in a shorter time. 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 a preferable upper limit of the reaction time, the reaction proceeds sufficiently even within 20 hours, preferably within 5 hours, more preferably within 3 hours.

  Here, by setting the reaction time in step 2 to the above-described conditions, it is possible to sufficiently consume the sulfidizing agent as a reaction raw material, in other words, to complete the reaction. Here, the completion of the reaction means that most of the sulfidizing agent charged as a reaction raw material, that is, preferably 90% or more, more preferably 95% or more is consumed, and the reaction is further performed to 99% or more sulfide. It means to consume the agent. By bringing the reaction closer to completion, the nitrogen content of the resulting PAS tends to be reduced. The reason for this is not clear, but when the reaction is closer to completion, impurity components containing nitrogen are incorporated into the product PAS. I guess it will be difficult.

  In the reaction of step 1 and step 2, various known polymerization methods and reaction methods such as a batch method and a continuous method can be employed. Further, the atmosphere in the production is preferably a non-oxidizing atmosphere, preferably in an inert gas atmosphere such as nitrogen, helium, and argon. From the viewpoint of economy and ease of handling, a nitrogen atmosphere is preferable.

(9) Solid-liquid separation of reaction product; Step 3
In the embodiment of the present invention, a reaction product containing the target polyarylene sulfide is obtained by performing the above-described Step 1 and Step 2. Here, usually, the organic polar solvent and oligopolyarylene sulfide used in Step 1 and Step 2 are also included in the reaction product.

  In the embodiment of the present invention, as the step 3 subsequent to the steps 1 and 2, the reaction product obtained in the steps 1 and 2 is subjected to solid-liquid separation in a temperature range below the boiling point of the organic polar solvent at normal pressure. Thus, it is preferable to carry out a step of obtaining a solid mainly containing polyarylene sulfide and a filtrate mainly containing oligoarylene sulfide and an organic polar solvent. By performing Step 3 using the reaction product, it is possible to easily separate the polyarylene sulfide and the oligoarylene sulfide in the reaction product.

  The temperature at which the reaction product is subjected to solid-liquid separation is preferably below the boiling point of the organic polar solvent at normal pressure. Although it depends on the type of the organic soluble polar medium, the specific temperature may be 200 ° C. or lower, more preferably 150 ° C. or lower, and still more preferably 120 ° C. or lower. In addition, the lower limit of the separation temperature can be exemplified by 10 ° C. or higher, more preferably 15 ° C. or higher, and further preferably 20 ° C. or higher, but 50 ° C. or higher is also used for producing higher quality polyarylene sulfide. It is possible to obtain a polyarylene sulfide having a particularly high quality by setting the temperature to 80 ° C. or higher. In the above range, oligoarylene sulfide is highly soluble in organic polar solvents, while polyarylene sulfide contained in the reaction product tends to be difficult to dissolve in organic polar solvents. Separation is effective for obtaining high-quality polyarylene sulfide as a solid component with high accuracy.

  In addition, the method for performing solid-liquid separation is not particularly limited, and pressure filtration or vacuum filtration that is filtration using a filter, centrifugation or sedimentation separation that is separation based on a specific gravity difference between a solid content and a solution, and a combination of these methods Etc. can be adopted. As a simpler method, pressure filtration using a filter or vacuum filtration can be preferably employed. The filter used for the filtration operation is not particularly limited as long as it is stable under the conditions for solid-liquid separation. For example, commonly used filter media such as a wire mesh filter, a sintered plate, a filter cloth, and filter paper can be suitably used.

  In addition, the pore size of the filter can be adjusted over a wide range depending on the viscosity, pressure, temperature, particle size of the solid component in the reaction product, and the like of the slurry subjected to the solid-liquid separation operation. In particular, the particle diameter of the polyarylene sulfide recovered as a solid content from the reaction product in this solid-liquid separation operation, that is, the mesh diameter according to the particle diameter of the solid content present in the reaction product subject to solid-liquid separation. Alternatively, it is effective to select a filter pore size such as a pore size. The average particle size (median diameter) of the solid content in the reaction product to be subjected to solid-liquid separation can vary widely depending on the composition, temperature, concentration, etc. of the reaction product. As far as is known, the average particle size tends to be 1 to 200 μm. Therefore, a preferable average pore diameter of the filter can be exemplified by 0.1 μm or more, preferably 0.25 μm or more, and more preferably 0.5 μm or more. Moreover, 100 micrometers or less can be illustrated, 20 micrometers or less are preferable and 15 micrometers or less are more preferable. By using a filter medium having an average pore diameter in the above range, the polyarylene sulfide that permeates the filter medium tends to decrease, and the polyarylene sulfide tends to be easily separated and recovered.

  In addition, there is no particular limitation on the atmosphere when performing the solid-liquid separation, but if the polyarylene sulfide, the organic polar solvent, and the oligo PAS are oxidatively deteriorated depending on conditions such as the time and temperature at the time of contact, they are non-oxidative. It is preferable to carry out in an atmosphere. Note that the non-oxidizing atmosphere is an atmosphere having a gas phase oxygen concentration of 5% by volume or less, preferably 2% by volume or less, and more preferably substantially free of oxygen, that is, an inert gas such as nitrogen, helium, or argon. Refers to the atmosphere. Among these, it is particularly preferable to carry out in a nitrogen atmosphere from the viewpoint of economy and ease of handling.

  Examples of the filter used for solid-liquid separation include, but are not limited to, a sieve, a vibrating screen, a centrifuge, a sedimentation separator, a pressure filter, a suction filter, and the like. In addition, from the viewpoint of performing in a non-oxidizing atmosphere which is a preferable atmosphere for solid-liquid separation as described above, it is possible to select a filter having a mechanism that can easily maintain a non-oxidizing atmosphere during solid-liquid separation operation. preferable. For example, a filter capable of performing a filtration operation after sealing the inside of the filter after being replaced with an inert gas, or a filter having a mechanism capable of performing a filtration operation while flowing an inert gas can be used. . Among the filters exemplified above, the centrifugal separator, the sedimentation separator, and the pressure filter can be said to be preferable because such functions can be easily added, and the mechanism is particularly simple. A pressure filter is more preferable from the viewpoint of excellent economic efficiency.

  There is no restriction on the pressure when performing solid-liquid separation, but in order to perform solid-liquid separation in a shorter time, it is also possible to perform solid-liquid separation under pressure using the pressure filter exemplified above Specifically, it can be exemplified as a preferable pressure range of 2.0 MPa or less in gauge pressure, more preferably 1.0 MPa or less, still more preferably 0.8 MPa or less, and even more preferably 0.5 MPa or less. . In general, as the pressure increases, it is necessary to increase the pressure resistance of the equipment that performs solid-liquid separation, and such equipment must have a high degree of sealing performance at each part constituting it, and inevitably equipment. Expenses will increase. Generally available solid-liquid separators can be used in the above preferred pressure range.

  By performing Step 1 and Step 2 which are features in the method for producing polyarylene sulfide of the embodiment of the present invention, extremely efficient solid-liquid separation is possible when the obtained reaction product is subjected to solid-liquid separation. It is also a great feature of the embodiment of the present invention that an effect excellent in solid-liquid separation is obtained. Here, the solid-liquid separation property can be evaluated by the time required for solid-liquid separation when a certain amount of reaction product is solid-liquid separated. As a specific evaluation method, for example, a filter medium (filter) having a predetermined standard (pore diameter, material) and a predetermined area is installed in a pressure filtration device that can be sealed, and a predetermined amount of reaction product is charged therein. By measuring the time required to obtain a predetermined amount of filtrate under certain conditions (temperature, pressure, etc.), it is possible to make a comparative evaluation at a filtration rate in units of weight / (area / time). . More specifically, when a reaction product is filtered under conditions of 100 ° C. and 0.1 MPa using a PTFE membrane filter having an average pore diameter of 10 μm, the time required to obtain a predetermined amount of filtrate is measured. Evaluation is possible. On the other hand, the reaction product obtained by the conventional method for producing polyarylene sulfide, which does not perform Step 1 and Step 2, which is a feature of this method, is extremely filterable and filtration speed in such solid-liquid separation evaluation. There is a problem of being inferior. Here, in the embodiment of the present invention, an extremely high value of 50 kg / (m 2 · hr) or more tends to be obtained as the filtration rate, which is preferable in the various conditions described above in the steps 1 and 2 of the production of the cyclic polyarylene sulfide. By selecting a numerical range, it is possible to achieve extremely high values of 100 kg / (m 2 · hr) or higher and very high filtration rates reaching 150 kg / (m 2 · hr).

  In addition, prior to solid-liquid separation of the reaction product, an additional operation of distilling off part of the organic polar solvent contained in the reaction product to reduce the amount of the organic polar solvent in the reaction product is performed. Is also possible. As a result, the amount of the reaction product to be subjected to the solid-liquid separation operation is reduced, 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 is not particularly limited as long as the organic polar solvent is separated from the reaction product and the amount of the organic polar solvent contained in the reaction product can be reduced. Preferable methods include a method of distilling the organic polar solvent under reduced pressure or increased pressure, a method of removing the solvent by flash transfer, etc., and a method of distilling the organic polar solvent under reduced pressure or increased 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 cannot be uniquely determined, but is preferably 180 ° C. or higher, preferably 200 ° C. or higher. More preferred. Moreover, 300 degrees C or less is preferable, 280 degrees C or less is more preferable, and 250 degrees C or less is further more preferable.

  According to the solid-liquid separation here, most of the oligoarylene sulfide contained in the reaction product can be separated as a filtrate component, preferably 80% or more, more preferably 90% or more, and still more preferably 95% or more. Can be separated as a filtrate component. Therefore, the residual oligoarylene sulfide in the polyarylene sulfide recovered as a solid content can be reduced, whereby high-quality polyarylene sulfide can be recovered. In addition, when a part of the oligopolyarylene sulfide remains in the polyarylene sulfide separated as a solid content by solid-liquid separation, the oligoarylene sulfide can be washed by using a fresh organic polar solvent for the solid content. It is also possible to reduce the amount of arylene sulfide remaining in the solid content. The solvent used here may be any solvent that can dissolve the oligoarylene sulfide, and it is preferable to use the same solvent as the organic polar solvent used in Step 1 and Step 2 described above.

(10) Other post-treatment In the present invention, as a specific example of the solid-liquid separation in the above step 3, PAS can be obtained as a solid content, and the solid component thus obtained is an extremely high quality PAS. Yes, compared with PAS obtained by a known method, the heat loss (ΔW) and the chlorine content during melting are significantly reduced, and the weight molecular weight is 2,500 to 20,000, and the flow is high during melt processing. It has also achieved sexual expression.

  Here, when the solid component contains an organic polar solvent, it is possible to remove the organic polar solvent by adopting a known method as desired. Examples of the method for removing the organic polar solvent include a method of removing by distillation and a method of solvent substitution with various solvents miscible with the organic polar solvent.

  As a specific method of removing by distillation, a method of heating the solid component to preferably 100 to 300 ° C, more preferably 120 to 250 ° C, and still more preferably 150 to 200 ° C can be exemplified. The organic polar solvent can be efficiently removed by performing this heating under reduced pressure or under an air stream. In addition, the atmosphere at the time of heating can also be performed in a non-oxidizing atmosphere, and this tends to suppress the decomposition, coloring, crosslinking, etc. of PAS. On the other hand, if it is desired to introduce a crosslinked structure into PAS, increase the melt viscosity, and further reduce volatile components, it is possible to select an oxidizing atmosphere. Here, the non-oxidizing atmosphere is an atmosphere having a gas phase oxygen concentration of 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. It indicates a gas atmosphere, and among these, a nitrogen atmosphere is particularly preferred from the viewpoint of economy and ease of handling. On the other hand, the oxidizing atmosphere refers to an atmosphere having a gas phase oxygen concentration of 5% by volume or more, preferably 10% by volume or more, and air can also be used.

  It is also possible to further wash the PAS from which the organic polar solvent has been removed in this manner using various solvents described later, thereby further reducing the ionic compound, oligoarylene sulfide, and organic polar solvent remaining in the PAS. It tends to be possible.

  Specific examples of the solvent replacement with various solvents include a method of solid-liquid separation after mixing the solid component with various solvents miscible with the organic polar solvent. It is also possible to repeat this operation as desired. It is important that the various solvents used here are miscible with the organic polar solvent, and are selected according to the characteristics of the organic polar solvent, but those that do not substantially cause undesirable side reactions such as decomposition and crosslinking of PAS are preferable. Alcohol, phenol solvents such as methanol, ethanol, propanol, butanol, pentanol, ethylene glycol, propylene glycol, phenol, cresol, polyethylene glycol, chloroform, bromoform, methylene chloride, 1,2-dichloroethane, 1,1, Halogen solvents such as 1-trichloroethane, chlorobenzene, 2,6-dichlorotoluene, hydrocarbon solvents such as pentane, hexane, heptane, octane, cyclohexane, cyclopentane, benzene, toluene, xylene, acetone, methyl Ketone solvents such as ethyl ketone, diethyl ketone, methyl isobutyl ketone, methyl butyl ketone, acetophenone, etc., carboxyl such as methyl acetate, ethyl acetate, pentyl acetate, octyl acetate, methyl butyrate, ethyl butyrate, pentyl butyrate, methyl salicylate, ethyl formate Examples of the acid ester solvent and water include methanol, ethanol, propanol, butanol, pentanol, ethylene glycol, propylene glycol, chloroform, methylene chloride, 1,2-dichloroethane, pentane, hexane, heptane, octane, cyclohexane, Cyclopentane, acetone, methyl acetate, ethyl acetate, water are preferred, methanol, ethanol, propanol, ethylene glycol, chloroform, methylene chloride, 1,2-dichloroether. Emissions, acetone, ethyl acetate, particularly preferably water, methanol, acetone, water is more preferable. These solvents can be used as one kind or a mixture of two or more kinds.

  There are no particular restrictions on the atmosphere in which the solid component and various solvents are brought into contact, but if the PAS component or solvent is subject to oxidative degradation due to conditions such as temperature or time in contact, it is performed in a non-oxidizing atmosphere. It is desirable. There is no particular limitation on the temperature at which the solid component is brought into contact with the solvent, but since it is preferable to carry out under atmospheric pressure, it is desirable that the upper limit temperature be lower than the reflux temperature under atmospheric pressure of the solvent used. In the case of using a preferred solvent, for example, 20 to 150 ° C., preferably 30 to 100 ° C. can be exemplified as a specific temperature range. The time for which the solid component is brought into contact with the solvent varies depending on the type of solvent used, the temperature, and the like, and thus cannot be uniquely limited, but examples include 1 minute to 50 hours.

  The method of bringing the solid component into contact with the solvent is not particularly limited as long as a known general method may be used. For example, the solid component and the solvent are mixed and stirred as necessary, and then the above-described solid-liquid separation operation is performed. Thus, any method such as a method for recovering the solid component, a method for showering the solvent on the solid component on various filters, or a method based on the principle of the Soxhlet extraction method can be used. Although there is no restriction | limiting in particular in the usage-amount of the solvent at the time of making a solid component and a solvent contact, For example, the range of 0.5-100 can be illustrated by the bath ratio with respect to a solid component weight. When the bath ratio is within such a range, it is easy to uniformly mix the solid component and the solvent, and the organic polar solvent can be efficiently separated from the solid component. When the contact between the solid component and the solvent is repeated, a sufficient effect can often be obtained even with a small bath ratio.

  The solid component from which the organic polar solvent thus obtained has been removed contains the solvent used for solvent substitution, and can be dried under normal pressure and / or reduced pressure as desired. The drying temperature is preferably in the range of 50 to 280 ° C, and more preferably in the range of 70 to 250 ° C. The drying atmosphere may be any of an inert atmosphere such as nitrogen, helium and reduced pressure, an oxidizing atmosphere such as oxygen and air, and a mixed atmosphere of air and nitrogen, preferably under reduced pressure, particularly under normal pressure. It is preferable to dry again under reduced pressure after drying to remove most of the solvent. The drying time is preferably 0.5 to 50 hours, preferably 1 to 30 hours, and more preferably 1 to 20 hours.

  The PAS obtained in the present invention is of a sufficiently high quality, but it can also be treated at a temperature of 130 to 260 ° C. in order to remove volatile components or to increase the cross-linking molecular weight. is there. When carrying out dry heat treatment for the purpose of suppressing cross-linking high molecular weight and removing volatile matter, the temperature is preferably from 130 to 250 ° C, more preferably from 160 to 250 ° C. Further, it is desirable that the oxygen concentration is less than 2% by volume, more preferably less than 1% by volume. Drying under reduced pressure is also a preferred method. The treatment time is preferably 0.5 to 50 hours, more preferably 1 to 20 hours, and still more preferably 1 to 10 hours. When the dry heat treatment is performed for the purpose of increasing the cross-linking molecular weight, the temperature is preferably 160 to 260 ° C, more preferably 170 to 250 ° C. Further, it is desirable that the oxygen concentration is 2% by volume or more, more preferably 8% by volume or more. The treatment time is preferably 1 to 100 hours, more preferably 2 to 50 hours, and even more preferably 3 to 25 hours. The heat treatment apparatus may be a normal hot air dryer or a heating apparatus with a rotary type or a stirring blade. However, for efficient and more uniform processing, a heating apparatus with a rotary type or a stirring blade is used. More preferably it is used.

(11) Generated PAS
The PAS obtained by the present invention is excellent in heat resistance, chemical resistance, flame retardancy, electrical properties and mechanical properties, and is used not only for injection molding, injection compression molding and blow molding, but also by extrusion molding to form sheets and films. , And can be formed into extruded products such as fibers and pipes. Further, as a remarkable effect manifested by the present invention, the amount of weight loss at the time of melting and heating is remarkably small as compared with PAS obtained by a known method, and the oligomer component content is also compared with PAS obtained by a known method. Since it is remarkably small, it can be preferably used for applications in which chemical resistance, oligomer elution amount and gas generation amount are regarded as important. Furthermore, since the chlorine content contained in PAS is remarkably reduced as compared with PAS obtained by a known method, it can be particularly preferably used for applications in which electrical characteristics, particularly insulation characteristics, are important.

  Here, although the oligoarylene sulfide described in the above item (5) is also an oligomer component, the PAS of the present invention has a feature that the oligoarylene sulfide content is low, and the preferable upper limit of the oligoarylene sulfide content is 1% or less. More preferably, it is 0.5% or less, still more preferably 0.4% or less, while a preferable lower limit is 0.01% or more, more preferably 0.05% or more. As a method for removing an oligomer component such as oligoarylene sulfide in a conventional PAS production method, a method by a quench method is known as exemplified in Patent Documents 2 and 5 in the prior art. Although this method can certainly reduce the oligomer component, it is difficult to obtain a low molecular weight PAS that is a feature of the present invention, and a PAS having a low molecular weight PAS and a low oligomer component content can be obtained. This is an excellent feature of the present invention.

  Here, the oligomer component content of PAS can be estimated as the weight fraction of the soluble portion of hot chloroform by extracting PAS with hot chloroform.

  In addition, the PAS obtained in the present invention may be used alone, or, as desired, inorganic fillers such as glass fiber, carbon fiber, titanium oxide, calcium carbonate, antioxidant, heat stabilizer, ultraviolet absorption. Agents, coloring agents, etc. can also be added. Polyamide, polysulfone, polyphenylene ether, polycarbonate, polyethersulfone, polyethylene terephthalate, polybutylene terephthalate, polyethylene, polypropylene, polytetrafluoroethylene, epoxy group, carboxyl group, carboxylic acid ester Contains resins such as olefin copolymers, polyolefin elastomers, polyether ester elastomers, polyether amide elastomers, polyamide imides, polyacetals, and polyimides having functional groups such as groups and acid anhydride groups. Rukoto can also.

  The present invention will be specifically described below with reference to examples. These examples are illustrative and not limiting. First, a method for evaluating samples obtained by the methods for producing polyarylene sulfides of Examples and Comparative Examples will be described.

<Analysis of dihalogenated aromatic compounds>
Quantification of the dihalogenated aromatic compound in the reaction mixture, reaction product and intermediate product during the reaction (quantification of p-dichlorobenzene) was carried out using gas chromatography under the following conditions.
Device: GC-2010 manufactured by Shimadzu Corporation
Column: DB-5 manufactured by J & W, Inc. 0.32 mm × 30 m (0.25 μm)
Carrier gas: Helium detector: Flame ionization detector (FID)

<Analysis of sulfiding agent>
Quantification of the sulfidizing agent in the reaction mixture, reaction product, and intermediate product during the reaction (quantification of sodium hydrosulfide) was carried out using ion chromatography under the following conditions.
Apparatus: HIC-20 Asper made by Shimadzu Corporation
Column: Shimadzu Shim-pack IC-SA2 (250 mm × 4.6 mm ID)
Detector: Electrical conductivity detector (suppressor)
Eluent: 4.0 mM sodium bicarbonate / 1.0 mM aqueous sodium carbonate flow rate: 1.0 mL / min Injection volume: 50 microliters Column temperature: 30 ° C.

  Hydrogen peroxide water was added to the sample to oxidize sulfide ions contained in the sample to sulfate ions, and then sulfate ions were quantified by the above analysis. The amount of sulfide ions in the sample was calculated by the method of subtracting the sulfate ion quantitative value when analyzing the untreated sample to which no hydrogen peroxide solution was added from the obtained sulfate ion quantitative value. The amount of sulfide ions calculated here is considered to correspond to the amount of unreacted sulfidizing agent contained in the data. Therefore, the amount of unreacted sulfidizing agent is calculated from the amount of sulfide ions calculated above, and the ratio of the amount of unreacted sulfidizing agent obtained and the amount of charged sulfidizing agent is used to determine the amount of sulfidizing agent in the sample. The reaction consumption rate was calculated.

<Evaluation of solid-liquid separation of reaction product>
Evaluation of the solid-liquid separability of the reaction product was performed under the following conditions.

  200 g of the obtained reaction product was collected and charged into a 300 mL flask. The reaction product was stirred with a magnetic stirrer and heated to 100 ° C. in an oil bath while nitrogen bubbling was performed on the reaction product slurry.

  A polytetrafluoroethylene (PTFE) membrane filter having a diameter of 90 mm and an average pore diameter of 10 μm is set on a filter holder KST-90-UH (effective filtration area of about 45 parallel centimeters) manufactured by ADVANTEC, The tank part was adjusted to 100 ° C. with a band heater.

  The reaction product 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. Starting from the time when the filtrate begins to be discharged from the lower part of the filter holder after pressurization, the time taken to discharge 50 g of the filtrate is measured, and the filtration rate based on the unit filtration area (kg / (m 2 · hr) ) Was calculated.

<Method for measuring molecular weight of polyphenylene sulfide>
As for the molecular weight of polyphenylene sulfide, number average molecular weight (Mn) and weight average molecular weight (Mw) were calculated in terms of polystyrene by gel permeation chromatography (GPC) which is a kind of size exclusion chromatography (SEC). The measurement conditions for GPC are shown below.
Apparatus: SSC-7110 manufactured by Senshu Scientific
Column: Shodex UT806M × 2
Column temperature: 210 ° C
Mobile phase: 1-chloronaphthalene detector: differential refractive index detector Detector temperature: 210 ° C.
Flow rate: 1.0 mL / min
Sample injection amount: 300 μL (slurry: about 0.2% by weight)

<Measuring method of melt viscosity of polyarylene sulfide>
Here, the melt viscosity of PAS can be measured by a dynamic viscoelasticity measuring method, and can be measured using a rotary dynamic viscosity measuring device (rheometer). The measurement conditions are shown below.
Apparatus: ARES-G2 (manufactured by TA Instrument)
Geometry: Parallel disk type (diameter 25 mm), cup (inner diameter about 28 mm) on the lower plate Operating temperature conditions: Temperature raised from 100 ° C. to 320 ° C. at 5 ° C./min. Measure viscosity at 300 ° C.
Angular frequency: 3.1 / second Measurement atmosphere: In nitrogen stream

<Chlorine content of PAS>
Using an automatic sample combustor AQF-100 manufactured by Dia Instruments, 1 to 2 mg of polymer is burned at a final temperature of 1000 ° C., and the generated gas component is absorbed in 10 mL of water containing a dilute oxidant, and the absorbing solution is carbonated. The total chlorine content in PAS was measured by using an ion chromatography system ICS1500 manufactured by DIONEX with a sodium / sodium bicarbonate mixed aqueous solution as a mobile phase.

<Measurement of total nitrogen content>
The nitrogen content of PAS 10 mg was measured using a trace nitrogen analyzer (manufactured by Mitsubishi Chemical Corporation, model “ND-100 type”) (reference material is pyridine).

<Measurement of oligomer content of polyarylene sulfide>
The content of the low molecular weight compound of polyarylene sulfide was estimated as the weight fraction of the soluble portion of hot chloroform by extracting PAS with hot chloroform. Extraction operation was performed by the following method.
(A) Soxhlet extraction was performed on 5 g of PAS using 100 g of chloroform at a bath temperature of 85 ° C. for 5 hours.
(B) Chloroform was distilled off from the extract obtained using a rotary evaporator.
(C) Next, vacuum drying was performed at 70 ° C. for 3 hours, the weight of the obtained solid content was determined, and the weight fraction with respect to the weight of PAS was calculated.

<Measurement method of weight loss rate (ΔW) at melting>
3 g of polymer was weighed into a glass ampoule having an abdomen of 100 mm × 25 mmφ, a neck of 255 mm × 12 mmφ, and a wall thickness of 1 mm, and then vacuum-sealed. Only the barrel of this glass ampoule was heated in an electric tubular furnace at 320 ° C. for 2 hours. After the ampoule was taken out, the ampoule neck which was not heated by the tubular furnace and was attached with volatile gas was cut out with a file and weighed. Next, the adhering gas was dissolved and removed with 5 g of chloroform, dried for 1 hour in a glass dryer at 60 ° C., and then weighed again. The difference in weight of the ampoule neck before and after removing the gas was defined as a weight reduction rate ΔW (%) at melting (% by weight relative to the polymer).

[Example 1]
<Preparation 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 (a) and 21.1 g of a 48 wt% aqueous sodium hydroxide solution (hydroxylated) 0.253 mol) as sodium, 35.4 g (0.241 mol) of p-dichlorobenzene (p-DCB) as dihalogenated aromatic compound (b), and N-methyl-2 as organic polar solvent (c) -A reaction mixture was prepared by charging 600 g (6.05 mol) of pyrrolidone (NMP). 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. In addition, an arylene unit (corresponding to p-DCB charged as a dihalogenated aromatic compound) per mole of sulfur component in the reaction mixture (per mole of sulfur atom contained in sodium hydrosulfide charged as a sulfidizing agent). The amount was 1.00 mol.

<Step 1>
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 1.0 MPa as a gauge pressure. Thereafter, the reaction mixture was heated at 250 ° C. for 2 hours to be reacted.

<Step 2>
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. By this operation, the arylene unit per mole of the sulfur component in the reaction mixture (corresponding to the total amount of p-DCB charged as the dihalogenated aromatic compound in Step 1 and Step 2) was 1.10 mole. 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 394 g of liquid components, the high pressure valve was closed and sealed. Next, the reaction product was recovered by quenching to near room temperature.

<Analysis and evaluation of reaction products>
A part of the obtained reaction product was dispersed in a large excess of water to recover a component insoluble in water, and a component insoluble in the recovered water was 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 composed of phenylene sulfide units.

  As a result of analyzing the obtained reaction product 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 It was 96%. Moreover, as a result of evaluating the solid-liquid separability of the obtained reaction product, the filtration rate was 355 kg / (m 2 · hr).

<Step 3: Solid-liquid separation of reaction product and isolation of PAS>
Except that the solid-liquid separation temperature was 50 ° C., the reaction product was subjected to solid-liquid separation in the same manner as in the above-described solid-liquid separation evaluation to obtain a solid content. 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 mixture was stirred at 70 ° C. for 15 minutes. The operation of suction filtration with a glass filter was repeated 4 times in total. The obtained solid was treated at 70 ° C. for 3 hours in a vacuum dryer to obtain a dry solid as polyarylene sulfide.

  As a result of analysis of this isolated dry solid, it was found from the absorption spectrum in infrared spectroscopic analysis that it was polyphenylene sulfide and the weight average molecular weight was 10,300 in terms of polystyrene. Moreover, the weight reduction rate (ΔW) at the time of melting is 0.52%, the chlorine content is 2,900 ppm, the nitrogen content is 800 ppm, the melt viscosity is 0.6 Pa · s, and the oligomer component content is 0.30%. Met.

  From the results of Example 1, according to the method for producing a polyarylene sulfide of the present invention, a high-quality polyarylene sulfide having a low impurity content can be obtained in a high yield, and a viewpoint with a low molecular weight PAS is obtained. But it turns out that both are compatible.

[Example 2]
A polyarylene sulfide was obtained by performing the same isolation operation as in Example 1 except that the solid-liquid separation temperature in Step 3 was 100 ° C. The resulting polyarylene sulfide was found to have a weight average molecular weight of 13,000 in terms of polystyrene. Moreover, the weight reduction rate (ΔW) upon melting is 0.38%, the chlorine content is 2,400 ppm, the nitrogen content is 430 ppm, the melt viscosity is 1.5 Pa · s, and the oligomer component content is 0.27%. Met.

[Example 3]
The amount of p-DCB used as the dihalogenated aromatic compound (b) in the preparation of the reaction mixture was changed to 33.7 g (0.229 mol), and the amount of arylene units per mol of sulfur component in the reaction mixture was changed. The process up to Step 1 was performed in the same manner as in Example 1 except that the amount was 0.95 mol.

  Next, except that the p-DCB charged in Step 2 was changed to 5.31 g, Step 2 and the subsequent steps were performed until isolation of polyarylene sulfide in the same manner as in Example 1 (sulfur component 1 in the reaction mixture in Step 2). The amount of arylene units per mole is 1.10 moles).

  The isolated PAS has a weight average molecular weight of 9,600 in terms of polystyrene, a weight loss rate (ΔW) of 0.32% upon melting, a chlorine content of 1,800 ppm, a nitrogen content of 990 ppm, and a melt viscosity of 0.4 Pa · s and the oligomer component content were 0.30%.

  From the results of Example 3, it was found that a higher quality and lower molecular weight PAS can be obtained by setting the molar ratio of the arylene component to the sulfur component in step 1 and step 2 to be a more preferable condition of the present invention. .

[Example 4]
Subsequently, polyarylene sulfide was isolated in the same manner as in Example 3 except that p-DCB charged in Step 2 was changed to 2.66 g (per mole of sulfur component in the reaction mixture in Step 2). The amount of the arylene unit is 1.08 mol).

  The isolated PAS has a weight average molecular weight of 12,100 in terms of polystyrene, a weight reduction rate (ΔW) of 0.35% when melted, a chlorine content of 1,450 ppm, a nitrogen content of 460 ppm, and a melt viscosity of The content of the oligomer component was 1.1 Pa · s and 0.29%.

  From the results of Example 4, it was found that a higher quality and lower molecular weight PAS can be obtained by setting the molar ratio of the arylene component to the sulfur component in step 1 and step 2 to be a more preferable condition of the present invention. .

[Example 5]
Here, an example of producing a polyarylene sulfide with a more preferable ratio of the raw material composition in the preparation of the reaction mixture is shown.

<Preparation of reaction mixture>
A reaction mixture was prepared in the same manner as in Example 1 except that the 48 wt% aqueous sodium hydroxide solution charged in a stainless steel autoclave equipped with a stirrer was reduced to 20.4 g (0.245 mol as sodium hydroxide).

<Steps 1-3>
Subsequently, after performing Steps 1 and 2 in the same manner as in Example 1, in Step 3, the solid-liquid separation temperature was set to 100 ° C. in the same manner as in Example 2 to obtain polyarylene sulfide. The resulting polyarylene sulfide had a weight average molecular weight of 12,000 in terms of polystyrene, a weight reduction rate (ΔW) of 0.30% when melted, a chlorine content of 2,300 ppm, a nitrogen content of 280 ppm, and a melt viscosity. Was 1.1 Pa · s, and the oligomer component content was 0.28%.

  It was found that a higher quality polyarylene sulfide can be obtained by setting the raw material composition of the reaction mixture used for the production of the polyarylene sulfide to a preferred composition of the present invention.

[Example 6]
Here, in the preparation of the reaction mixture, an example in which the raw material composition is set to a more preferable ratio and the reaction time is optimized to produce polyarylene sulfide.

  After preparing the reaction mixture and carrying out step 1 in the same manner as in Example 5, the heat holding time at 250 ° C. (1 hour in Example 5) after adding DCB in step 2 was extended to 2 hours. A polyarylene sulfide was obtained in the same manner as in Example 5 except that. The resulting polyarylene sulfide had a weight average molecular weight of 9,400 in terms of polystyrene, a weight reduction rate (ΔW) of 0.29% when melted, a chlorine content of 2,300 ppm, a nitrogen content of 250 ppm, and a melt viscosity. Was 0.38 Pa · s, and the oligomer component content was 0.28%.

  It has been found that the polyarylene sulfide can be produced in a high quality polyarylene sulfide by further reducing the amount of impurities by setting the raw material composition of the reaction mixture as a preferable condition of the present invention.

[Comparative Example 1]
Here, an example of a method for producing a polyarylene sulfide having a low molecular weight by a conventional method for producing a polyarylene sulfide will be described.

  In a stainless steel autoclave equipped with a stirrer and bottom plug valve, 8.26 kg (70.0 mol) of 47.5% sodium hydrosulfide aqueous solution and 2.94 kg (70.6 mol) of 96% sodium hydroxide were added to 3 kg of ion-exchanged water. And 14.6 kg (147 mol) of N-methyl-2-pyrrolidone (NMP) were charged.

  In order to remove moisture in the charged raw materials, the mixture was gradually heated to 235 ° C. over about 3 hours while passing nitrogen at normal pressure. When about 7.8 kg of distillate was distilled, heating was stopped. As a result of analyzing the distillate by gas chromatography, it was found that 0.3 kg of NMP was contained in the liquid, and NMP in the system was 14.3 kg. In addition, as a result of analyzing the aqueous solution obtained by passing the gas scattered outside the system in this operation to the aqueous sodium hydroxide solution, it was found that 1.4 mol of sulfur was scattered by this operation. Was found to be 68.6 mol.

  Thereafter, the mixture was cooled to 180 ° C., 10.8 kg (73.7 mol) of p-dichlorobenzene (p-DCB) and 5.6 kg (56.0 mol) of NMP were added, and the reaction vessel was sealed under nitrogen gas. At this time, the organic polar solvent NMP is 19.9 kg (corresponding to about 20.4 L at 25 ° C.) with respect to 68.6 mol of the sulfur component which is a sulfidizing agent contained in the reaction mixture in the reactor. The amount of organic polar solvent per mole of sulfur component in the reaction mixture was about 0.3 L. The molar ratio of the arylene component to 1 mol of the sulfur component was 1.075.

  Next, the temperature was raised from 200 ° C. to 275 ° C. at a rate of 0.6 ° C./min and held at 275 ° C. for 1 hour while stirring at 240 rpm and the internal temperature increased to 200 ° C. over about 1 hour. Then, it cooled to 100 degrees C or less over about 2 hours, and collect | recovered the reaction product.

  About 0.5 kg of the obtained reaction product was mixed with 2.5 liters of ion exchange water, stirred at 75 ° C. for 15 minutes, and then filtered through a filter to obtain a solid content. This solid content was again dispersed in 2.5 liters of ion exchange water, stirred for 15 minutes at 75 ° C., and then filtered through a filter to obtain a solid content twice. The obtained cake was similarly dispersed in 2.5 liters of ion-exchanged water, charged in an autoclave equipped with a stirrer, the inside of the autoclave was replaced with nitrogen, and the temperature was raised to 195 ° C. Thereafter, the autoclave was cooled and the contents were taken out. The contents were filtered through a filter to obtain a cake. The obtained cake was dried at 120 ° C. under a nitrogen stream to obtain a dry solid.

  As a result of analysis of this isolated dry solid, it was found from the absorption spectrum in infrared spectroscopic analysis that it was polyphenylene sulfide and the weight average molecular weight was 14,700 in terms of polystyrene. Further, the weight reduction rate (ΔW) upon melting is 1.40%, the chlorine content is 9,100 ppm, the nitrogen content is 1200 ppm, the melt viscosity is 6.8 Pa · s, and the oligomer component content is 5.2%. Met.

  From the results of Comparative Example 1, according to the conventional method for producing polyarylene sulfide, low molecular weight polyarylene sulfide can be produced, but the weight reduction rate during melting is large, and the chlorine and nitrogen contents are also large. It turned out that it was difficult to achieve both low molecular weight and quality.

[Comparative Example 2]
Here, the example which examined the control of the molar ratio of a sulfidation agent and a dihalogenated aromatic compound currently disclosed as a technique of reducing chlorine content in the manufacturing method of a polyarylene sulfide is shown.

  The amount of polyarylene sulfide was the same as in Comparative Example 1 except that the amount of p-dichlorobenzene charged was 10.4 kg (70.6 mol) and the molar ratio of the arylene component to 1 mol of the sulfur component was reduced to 1.03. Manufactured.

  It was found that the weight average molecular weight of the isolated polyphenylene sulfide was 19,500 in terms of polystyrene. Moreover, the weight reduction rate (ΔW) upon melting was 1.20%, the chlorine content was 4,000 ppm, the nitrogen content was 1400 ppm, the melt viscosity was 26 Pa · s, and the oligomer component content was 4.8%. It was.

  From the results of Comparative Example 2, it was found that by adjusting the molar ratio of the sulfidizing agent and dihalogenated aromatic compound used as a raw material, a certain low chlorination is possible, but the effect is insufficient. . In addition, this method has almost no effect on reducing the weight loss rate at melting and reducing the nitrogen content, and it has been found that the molecular weight of the resulting polyarylene sulfide tends to be large, and both low molecular weight and quality are compatible. Found it difficult.

[Comparative Example 3]
Here, an example in which a method using a monohalogenated aromatic compound, which is disclosed as another method for reducing the molecular weight and reducing the chlorine content in the conventional method for producing polyarylene sulfide, is shown.

  Comparison except that the amount of p-dichlorobenzene charged was changed to 10.1 kg (68.6 mol), and 0.77 kg (6.86 mol) of monochlorobenzene was also added at the same time when p-dichlorobenzene was charged. In the same manner as in Example 1, polyarylene sulfide was produced. By this change, the molar ratio of the arylene component to 1 mol of the sulfur component in the production of polyarylene sulfide was 1.10.

  The isolated polyphenylene sulfide was found to have a weight average molecular weight of 10,000 in terms of polystyrene. Moreover, the weight reduction rate (ΔW) at the time of melting is 1.52%, the chlorine content is 6,000 ppm, the nitrogen content is 1500 ppm, the melt viscosity is 0.7 Pa · s, and the oligomer component content is 5.9%. Met.

  From the result of Comparative Example 3, it is possible to reduce the molecular weight of polyarylene sulfide by using a monohalogenated aromatic compound, but the effect of low chlorination is insufficient, and the weight reduction rate during melting is further reduced. It has been found that there is almost no effect in reducing or reducing the nitrogen content.

[Comparative Example 4]
Here, in the conventional method for producing polyarylene sulfide, a method for separating the PAS component by filtering the reaction product through a mesh wire mesh and a method for washing and purifying the PAS component with an organic polar solvent, which are disclosed as methods for improving the quality, are disclosed. The example which examined the method of combining is shown.

  In a stainless steel autoclave equipped with a stirrer and bottom plug valve, 8.26 kg (70.0 mol) of 47.5% sodium hydrosulfide aqueous solution and 2.94 kg (70.6 mol) of 96% sodium hydroxide were added to 3 kg of ion-exchanged water. Aqueous solution, 1.72 kg (21.0 mol) of sodium acetate and 14.6 kg (147 mol) of N-methyl-2-pyrrolidone (NMP) were charged.

  In order to remove moisture in the charged raw materials, the mixture was gradually heated to 235 ° C. over about 3 hours while passing nitrogen at normal pressure. When about 7.8 kg of distillate was distilled, heating was stopped. As a result of analyzing the distillate by gas chromatography, it was found that 0.3 kg of NMP was contained in the liquid, and NMP in the system was 14.3 kg. In addition, as a result of analyzing the aqueous solution obtained by passing the gas scattered outside the system in this operation to the aqueous sodium hydroxide solution, it was found that 1.4 mol of sulfur was scattered by this operation. Was found to be 68.6 mol.

  After cooling to 180 ° C., 10.3 kg (70.3 mol) of p-dichlorobenzene (p-DCB) and 5.6 kg (56.0 mol) of NMP were added, and the reaction vessel was sealed under nitrogen gas. At this time, the organic polar solvent NMP is 19.9 kg (corresponding to about 20.4 L at 25 ° C.) with respect to 68.6 mol of the sulfur component which is a sulfidizing agent contained in the reaction mixture in the reactor. The amount of organic polar solvent per mole of sulfur component in the reaction mixture was about 0.3 L. The molar ratio of the arylene component to 1 mol of the sulfur component was 1.025.

  Next, the temperature was raised from 200 ° C. to 270 ° C. at a rate of 0.6 ° C./min, and held at 270 ° C. for 2 hours while stirring at 240 rpm to increase the internal temperature to 200 ° C. over about 1 hour. Thereafter, 2.40 kg (133 mol) of water was injected while cooling from 270 ° C. to 250 ° C. over 15 minutes. Next, the mixture was gradually cooled from 250 ° C. to 220 ° C. over 75 minutes, and then rapidly cooled to near room temperature, and the contents were taken out. The reaction product was recovered by cooling to 100 ° C. or lower over about 2 hours.

  About 0.5 kg of the obtained reaction product was diluted with about 1.5 liters of NMP, stirred as a slurry at 85 ° C. for 30 minutes, and filtered through an 80 mesh wire mesh (aperture 0.175 mm) to obtain a solid. Obtained. The resulting solid was similarly stirred with about 1.5 liters of NMP and filtered off. The obtained solid was diluted with 2.5 liters of ion-exchanged water, stirred at 70 ° C. for 30 minutes, and then filtered through an 80-mesh wire net to collect the solids a total of 5 times to collect the solids. . The solid thus obtained was dried at 120 ° C. under a nitrogen stream to obtain a dry solid.

  As a result of analysis of this isolated dry solid, it was found from the absorption spectrum in infrared spectroscopic analysis that it was polyphenylene sulfide and the weight average molecular weight was 48,000 in terms of polystyrene. The weight reduction rate (ΔW) upon melting was 0.26%, the chlorine content was 1,700 ppm, the nitrogen content was 820 ppm, the melt viscosity was 95 Pa · s, and the oligomer component content was 0.31%. It was.

  From the result of Comparative Example 4, according to the conventional method for improving the quality of polyarylene sulfide, it is possible to reduce the chlorination and the weight reduction rate at the time of melting, and also to reduce the nitrogen content to a certain extent. It was found that the molecular weight of the resulting PAS was very large, and it was difficult to achieve both low molecular weight and quality.

[Comparative Example 5]
Here, an example of production of an ultra-low molecular weight polyarylene sulfide according to the prior art, that is, an organic polar solvent of 1.25 liters or more with respect to 1 mol of a sulfurizing agent, a dihalogenated aromatic compound, and a sulfur component of the sulfiding agent. However, unlike the present invention, a polyarylene sulfide was produced by solid-liquid separation of the reaction mixture obtained by obtaining a reaction mixture containing polyarylene sulfide without partitioning step 1 and step 2. An example is shown.

<Preparation of reaction mixture containing polyarylene sulfide>
In a stainless steel autoclave (reaction vessel) equipped with a stirrer, 46.75 g of a 48 wt% sodium hydrosulfide aqueous solution (0.40 mol as sodium hydrosulfide) and 35.00 g of a 48 wt% sodium hydroxide aqueous solution (0.42) Mol), 1000 g (10.1 mol) of NMP, and 61.7 g (0.42 mol) of p-dichlorobenzene (p-DCB). After sufficiently purging the inside of the reaction vessel with nitrogen, it was sealed by pressurizing with pressurized nitrogen to 0.3 MPa with a gauge pressure.

  While stirring at 400 rpm, the temperature in the reaction vessel was increased from room temperature to 200 ° C. over about 1 hour. At this stage, the pressure in the reaction vessel was 0.9 MPa as a gauge pressure. Next, the temperature in the reaction vessel was raised from 200 ° C. to 250 ° C. over about 30 minutes. The pressure in the reaction vessel at this stage was 1.5 MPa as a gauge pressure. After maintaining at 250 ° C. for 2 hours, the reaction product obtained from the reaction vessel was recovered by quenching to near room temperature.

  As a result of analyzing the obtained reaction product by gas chromatography and high performance liquid chromatography, the consumption rate of monomeric p-DCB was 92%.

<Solid-liquid separation of reaction product>
The contents obtained above, that is, a reaction product containing at least polyarylene sulfide, NMP, and NaCl as a by-product salt, are charged into an eggplant flask, and the inside of the flask is sufficiently purged with nitrogen, and then adjusted to about 100 ° C. with stirring. The reaction product was separated into solid and liquid by hot pressure filtration using pressurized nitrogen. By this operation, a wet solid was obtained.

  The obtained wet solid was sufficiently washed with warm water and then dried to obtain a dry solid. As a result of the analysis of the dried solid, it was found from the absorption spectrum in infrared spectroscopic analysis that it was a linear polyphenylene sulfide and the weight average molecular weight was 10,000 in terms of polystyrene. The weight reduction rate (ΔW) upon melting is 1.60%, the chlorine content is 5,400 ppm, the nitrogen content is 1100 ppm, the melt viscosity is 0.6 Pa · s, and the oligomer component content is 0.38%. Met.

[Comparative Example 6]
Polyarylene sulfide was produced in the same manner as in Comparative Example 5 except that the amount of p-dichlorobenzene charged was changed to 63.2 g (0.43 mol).

  The isolated polyarylene sulfide was found to have a weight average molecular weight of 9,200 in terms of polystyrene. The weight reduction rate (ΔW) upon melting is 1.75%, the chlorine content is 6,800 ppm, the nitrogen content is 1000 ppm, the melt viscosity is 0.35 Pa · s, and the oligomer component content is 0.38%. Met.

[Comparative Example 7]
Here, as a production example of a low molecular weight polyarylene sulfide according to the prior art, polyarylene sulfide is produced with a smaller amount of solvent used than in Comparative Examples 5 and 6, and as a purification method, disclosed in JP-A-2009-167395. A filtrate component comprising polyarylene sulfide, oligoarylene sulfide and an organic polar solvent by subjecting the reaction mixture to a first solid-liquid separation at a temperature sufficient to dissolve the polyarylene sulfide, An example is shown in which polyarylene sulfide is produced by subjecting the filtrate component to a second solid-liquid separation after setting the filtrate component to a temperature at which polyarylene sulfide does not dissolve.

<Preparation of reaction mixture containing polyarylene sulfide>
In a stainless steel autoclave equipped with a stirrer, 58.4 g (0.50 mol) of a 48 wt% aqueous solution of sodium hydrosulfide and 23.0 g (0.53 mol) of 96% sodium hydroxide were dissolved in 50 g of ion-exchanged water. An aqueous solution, 198 g (2.00 mol) of N-methyl-2-pyrrolidone (NMP) was charged. After the rectification tower was attached to the autoclave, it was gradually heated to an internal temperature of 210 ° C. over about 3 hours while stirring through nitrogen at normal pressure. During this period, 80 g was distilled out of the system from the rectification column. The amount of hydrogen sulfide scattered was 0.012 mol. As a result of analyzing the distillate by gas chromatography, it was found that the distillate was a mixture of 76.5 g of water and 3.5 g of NMP, and the amounts of water and NMP in the reaction system were 3.8 g and 195 g, respectively. .

  After completion of the distillation, the reaction vessel was cooled to about 160 ° C., 73.1 g (0.50 mol) of p-dichlorobenzene (p-DCB) and 300 g (3.0 mol) of NMP were added, and the reaction vessel was charged with nitrogen. Sealed under gas. While stirring, the mixture was heated and heated from 200 ° C. to 250 ° C. over about 50 minutes, held at 250 ° C. for 2 hours, and then rapidly cooled to near room temperature to obtain a reaction product.

<First solid-liquid separation>
100 g of the reaction product obtained above was charged into a stainless steel pressure vessel equipped with a bottom plug valve and a glass filter (average opening 10 μm) at the bottom. After heating to 180 ° C. with stirring under normal pressure, the vessel was sealed under nitrogen. Subsequently, it heated to 250 degreeC and hold | maintained for 1 hour.

  A cooling pipe was attached to the bottom plug valve outlet of the container, and the bottom plug valve was opened for filtration. The filtrate was collected while introducing nitrogen at 0.3 MPa into the container at the stage when the filtration rate was lowered. By this operation, about 84 g of filtrate and 14 g of solid content were recovered.

<Second solid-liquid separation>
The filtrate obtained by the first solid-liquid separation was heated to 100 ° C. At this stage, the filtrate obtained by the first solid-liquid separation was in the form of a slurry containing an insoluble part. The slurry was suction filtered with a PTEF filter (average opening 10 μm). By this operation, about 11 g of solid content and about 71 g of filtrate were recovered.

  The obtained solid content was dispersed in 300 g of a 1% aqueous acetic acid solution, then heated to 70 ° C. and stirred for 30 minutes. The slurry was filtered through a glass filter (average pore diameter of 10 to 16 μm) to obtain a solid content. The operation of dispersing the obtained solid content in 100 g of ion-exchanged water, stirring at 70 ° C. for 30 minutes and filtering to obtain the solid content was repeated three times. The obtained solid content was subjected to vacuum drying at 70 ° C. overnight to obtain about 7.1 g of a dry solid (yield 84% based on the charged sulfidizing agent).

  As a result of analyzing the solid thus obtained, it was found from the absorption spectrum in infrared spectroscopic analysis that it was a polymer (PPS) composed of phenylene sulfide units, and was a polymer having a weight average molecular weight of 18000 from GPC measurement. . The alkali metal content was 550 ppm, and reduction of metal impurities was confirmed. On the other hand, the weight reduction rate (ΔW) upon melting is 1.1%, the chlorine content is 3,600 ppm, the nitrogen content is 1100 ppm, the melt viscosity is 7.8 Pa · s, and the oligomer component content is 0.32%. In terms of the amount of gas during heating and the content of chlorine and nitrogen, the quality was insufficient compared to the method of the present invention.

Claims (8)

A reaction mixture comprising at least a sulfidizing agent (a), a dihalogenated aromatic compound (b) and an organic polar solvent (c), wherein 1.25 liters or more and 50 liters per mole of sulfur component in the reaction mixture A method for producing a polyarylene sulfide by heating and reacting the reaction mixture containing the following organic polar solvent (c), wherein the reaction product obtained in the following Step 1 and Step 2 has a weight A method for producing a polyarylene sulfide, wherein a polyarylene sulfide having an average molecular weight of 2,500 to 20,000 is isolated.
Step 1: heating the reaction mixture having an arylene unit of 0.80 mol or more and less than 1.05 mol per 1 mol of the sulfur component in the reaction mixture, so that the sulfiding agent (a) in the reaction mixture is heated. The process of making it react until 50% or more is consumed.
Step 2: After the step 1, after adding the dihalogenated aromatic compound (b) so that the arylene unit per mole of sulfur component in the reaction mixture is 1.05 mol or more and 1.50 mol or less A step of further heating to react to obtain a reaction product containing polyarylene sulfide. 2. The method for producing polyarylene sulfide according to claim 1, wherein the following step 3 is performed after the step 2 to isolate the polyarylene sulfide from the solid content separated by solid-liquid separation.
Step 3: A step of subjecting the reaction product obtained in Step 2 to solid-liquid separation in a temperature range below the boiling point of the organic polar solvent (c) at normal pressure. The method for producing polyarylene sulfide according to claim 1 or 2, wherein the arylene unit per mole of sulfur component in the reaction mixture in Step 1 is 0.80 mole or more and less than 1.00 mole. The polyarylene sulfide according to any one of claims 1 to 3, wherein in the step 1, the reaction is performed until 70% or more of the sulfidizing agent (a) in the reaction mixture is reacted and consumed. Manufacturing method. A polyarylene sulfide having a weight average molecular weight of 2,500 to 20,000, and having a weight loss of 1.0% or less when heated at 320 ° C. for 2 hours under reduced pressure. The polyarylene sulfide according to claim 5, wherein the chlorine content is 5,000 ppm or less. The polyarylene sulfide according to claim 5 or 6, wherein the oligomer component content is 0.01% or more and 1.0% or less. The polyarylene sulfide according to any one of claims 5 to 7, having a melt viscosity of 0.01 to 10 Pa · s.