WO2025164375A1 - Polyarylene sulfide copolymer particles and method for producing same - Google Patents

Abstract

Polyarylene sulfide copolymer particles each have a median diameter D50 of 1-1,000 μm inclusive, a glass transition point by differential scanning calorimetry of 95-190°C inclusive and a sphericity of 80-100 inclusive. The present invention addresses the problem of obtaining polyarylene sulfide copolymer particles having a high glass transition point and a high sphericity, and provides a simple and safe method for producing the same.

Description

Polyarylene sulfide copolymer particles and method for producing the same

The present invention relates to polyarylene sulfide copolymer particles and a method for producing the same.

Polyarylene sulfides, typified by polyphenylene sulfide (hereinafter sometimes abbreviated as PPS), have properties that make them ideal for engineering plastics, such as excellent heat resistance, barrier properties, moldability, chemical resistance, electrical insulation, and moist heat resistance, and are used in a variety of electrical and electronic parts, machine parts, automotive parts, films, fibers, and more, primarily for injection molding and extrusion molding. Due to their excellent properties, the range of applications for polyarylene sulfides has been expanding in recent years.

PPS, a typical polyarylene sulfide, is a crystalline polymer that generally has a glass transition point of 80-90°C and a melting point of 275-285°C, and is often used under high-temperature conditions due to its excellent heat resistance. It is also widely used in applications that take advantage of its excellent chemical resistance.

However, while the aforementioned PPS, a typical example of polyarylene sulfide, has a high melting point and can withstand high-temperature use, it suffers from the problem that its rigidity drops sharply at temperatures above the glass transition point, 80-90°C, compared to temperatures below that point. Various studies have been conducted to improve the glass transition point of polyarylene sulfide; for example, Patent Documents 1 to 3 disclose polyarylene sulfide copolymers obtained by reacting polyarylene sulfide having reactive functional groups with rigid molecules.

Polyarylene sulfide copolymers, which have excellent chemical resistance and higher heat resistance, are generally used in injection molding, injection compression molding, blow molding, extrusion molding, etc., but by granulating polyarylene sulfide copolymers, they can be used as heat-resistant additives in the adhesive materials, paints, and polymer compounds fields, and as raw materials for three-dimensional modeling using powder bed fusion, and are expected to be useful in a wider range of applications. Furthermore, when polyarylene sulfide copolymers are blended with components selected from fillers and other additives to produce resin compositions, the use of granular polyarylene sulfide copolymers is expected to enable the efficient production of more uniform resin compositions.

Various methods for producing thermoplastic resin particles have been investigated. For example, Patent Documents 4 and 5 disclose PPS or polyarylene sulfide particles obtained by dissolving PPS or polyarylene sulfide in a solvent and precipitating the resulting solution; Patent Document 6 discloses polyarylene sulfide resin powder obtained by dry-pulverizing polyarylene sulfide; and Patent Documents 7 and 8 disclose PPS particles obtained by adding another thermoplastic polymer to PPS, melt-kneading the mixture, and then removing the other thermoplastic polymer.

International Publication No. 2019/151288 International Publication No. 2022/045105 International Publication No. 2021/020334 Japanese Patent Application Laid-Open No. 2008-231250 WO 2009/119466 International Publication No. 2019/203256 JP 2014-43522 A Japanese Patent Application Publication No. 10-273594

The polyarylene sulfide copolymers disclosed in Patent Documents 1 to 3 have high glass transition points, but the polyarylene sulfide copolymers are produced simply by heating them in a molten state in the absence of a solvent, and no polyarylene sulfide copolymer particles are obtained. Furthermore, while there is a description of producing polyarylene sulfide copolymers in the presence of a solvent, there is no description of particles or specific production methods. Patent Document 3 describes a method of using powdered polyarylene sulfide copolymer as a method of producing a fiber-reinforced polyarylene sulfide copolymer composite substrate, but there is no description of a specific method of obtaining powdered polyarylene sulfide copolymer or a method of producing a composite substrate using powdered polyarylene sulfide copolymer.

The PPS or polyarylene sulfide particles disclosed in Patent Documents 4 and 5 are produced by dissolving PPS or polyarylene sulfide in a solvent and precipitating it. When this production method is applied to polyarylene sulfide copolymers with high glass transition points, differences in solubility have been found to result in problems with reduced particle yield and reduced molecular weight of the polyarylene sulfide copolymer.

Patent Document 6 discloses polyarylene sulfide resin powder for thermoplastic prepregs, but the only specific method of producing the powder is dry pulverization. Resin powder obtained by dry pulverization generally has an irregular shape, low sphericity, and is characterized by poor fluidity and dispersibility. Furthermore, as with the inventions described in Patent Documents 1 to 3, the resin is in the form of pellets or chunks that are produced by heating in a molten state, which presents the problem of difficulty in granulating it by dry pulverization.

Patent Documents 7 and 8 produce PPS particles, but add a thermoplastic polymer other than PPS, which requires a long reaction time for decomposition to remove the thermoplastic polymer, and there is also the problem of workers being exposed to the solvent.

The objective of the present invention is to provide polyarylene sulfide copolymer particles that can be used to produce three-dimensional objects with high molding density and excellent surface quality, reinforced fiber composite substrates with excellent mechanical properties, and molded articles made from them.

Another objective of the present invention is to provide a simple and safe production method for obtaining polyarylene sulfide copolymer particles that have a high glass transition temperature and high sphericity.

The present invention has been made to solve at least part of the above-mentioned problems, and can be realized by providing the following contents.
1. Polyarylene sulfide copolymer particles having a median diameter D50 of 1 μm or more and 1,000 μm or less, a glass transition point of 95° C. or more and 190° C. or less when measured using a differential scanning calorimeter, and a sphericity of 80 or more and 100 or less.
2. The polyarylene sulfide copolymer particles according to the above item 1, having a median diameter D50 of 1 μm or more and 150 μm or less.
3. The polyarylene sulfide copolymer particles according to 1 or 2 above, which have a weight average molecular weight Mw of 30,000 or more.
4. The polyarylene sulfide copolymer particles according to any one of 1 to 3 above, wherein the polyarylene sulfide copolymer constituting the polyarylene sulfide copolymer particles contains at least one bonding group selected from a sulfonyl group, a sulfinyl group, an ester group, an amide group, an imide group, an ether group, a urea group, a urethane group, and a siloxane group.
5. A method for producing polyarylene sulfide copolymer particles, comprising: step 1 of melt-kneading a polyarylene sulfide copolymer having a glass transition temperature of 95°C or higher and 190°C or lower as measured using a differential scanning calorimeter with a water-soluble thermoplastic resin; and step 2 of removing the water-soluble thermoplastic resin by washing with water or an alcohol.
6. The method for producing polyarylene sulfide copolymer particles according to the above item 5, wherein the viscosity ratio ηa/ηb of the melt viscosity (ηa) of the polyarylene sulfide copolymer to the melt viscosity (ηb) of the water-soluble thermoplastic resin is 0.1 or more and 1,000 or less.
7. A dispersion in which the polyarylene sulfide copolymer particles according to any one of 1 to 4 above are dispersed in a liquid.
8. A three-dimensional object molded from the polyarylene sulfide copolymer particles according to any one of 1 to 4 above.
9. A method for producing a reinforced fiber composite substrate, comprising the steps of dispersing the polyarylene sulfide copolymer particles according to any one of 1 to 4 above in reinforcing fibers, and melting the polyarylene sulfide copolymer particles to impregnate the reinforcing fibers.
10. A reinforcing fiber composite substrate produced by the method for producing a reinforcing fiber composite substrate according to 9 above.
11. A molded article obtained by molding the reinforcing fiber composite substrate of 10 above.
12. The molded article according to claim 11, which is an aircraft structural member.

The present invention provides polyarylene sulfide copolymer particles with a high glass transition temperature and high sphericity, as well as a simple and safe method for producing the same.

Furthermore, the polyarylene sulfide copolymer particles of the present invention can be used to obtain three-dimensional objects having high object density and excellent surface quality. Furthermore, the polyarylene sulfide copolymer particles of the present invention have excellent dispersibility when dispersed in reinforcing fibers, making it possible to obtain reinforced fiber composite substrates with excellent mechanical properties, and molded articles made thereof.

The following describes in detail an embodiment of the present invention.

[Polyarylene sulfide copolymer particles]
The lower limit of the glass transition point of the polyarylene sulfide copolymer particles is 95°C or higher, preferably 100°C or higher, and more preferably 110°C or higher. If the glass transition point is below 95°C, high rigidity cannot be obtained under high temperature conditions. The upper limit of the glass transition point is 190°C or lower, preferably 180°C or lower, and more preferably 160°C or lower. If the glass transition point exceeds 190°C, the chemical resistance of the molded product will be insufficient. The glass transition point is defined as the inflection point of the baseline shift detected when the polyarylene sulfide copolymer particles are heated from 0°C to 340°C at a rate of 20°C/min using a differential scanning calorimeter.

In order to obtain polyarylene sulfide copolymer particles having a glass transition temperature within the above range, for example, the molecular structure of the polyarylene sulfide copolymer that constitutes the polyarylene sulfide copolymer particles may contain rigid bonding groups such as sulfonyl groups, sulfinyl groups, ester groups, amide groups, imide groups, ether groups, urea groups, urethane groups, and siloxane groups.

The crystallization temperature of the polyarylene sulfide copolymer particles is preferably 150°C or higher, more preferably 160°C or higher, and even more preferably 170°C or higher. Having a lower limit for the crystallization temperature within the above range facilitates crystallization during molding and when blending components selected from fillers and other additives to produce a resin composition, which tends to result in excellent mechanical properties and chemical resistance and improved productivity. There is no particular upper limit for the crystallization temperature, but a range of 235°C or lower is typically used. The crystallization temperature is the peak crystallization temperature detected when the polyarylene sulfide copolymer particles are heated from 0°C to 340°C at a rate of 20°C/min using a differential scanning calorimeter, then held at 340°C for 1 minute, and then cooled to 100°C at a rate of 20°C/min.

The polyarylene sulfide copolymer particles preferably have a melting point of 300°C or less, more preferably 270°C or less, and even more preferably 260°C or less. Having an upper melting point within the above range facilitates melt molding processing. Furthermore, a melting point of 200°C or more is preferable, and a melting point of 220°C or more is even more preferable. Having a lower melting point within the above range is preferable because sufficient heat resistance is obtained when three-dimensional objects, reinforced fiber composite substrates, and molded articles made therefrom are obtained. The melting point is the melting peak temperature detected when the polyarylene sulfide copolymer particles are heated from 0°C to 340°C using a differential scanning calorimeter at a rate of 20°C/min, held at 340°C for 1 minute, cooled to 100°C at a rate of 20°C/min, held at 100°C for 1 minute, and then heated again to 340°C at a rate of 20°C/min.

The polyarylene sulfide copolymer that forms the polyarylene sulfide copolymer particles is a copolymer containing 70 mol% or more of arylene sulfide units, preferably 80 mol% or more. Here, the arylene sulfide unit is a repeating unit represented by the formula -(Ar-S)-. Ar can be a unit selected from the units represented by the following formulas (I) to (XI). Of these, the unit represented by formula (I) is particularly preferred.

R ¹ and R ² are substituents selected from hydrogen, alkyl groups having 1 to 12 carbon atoms, alkoxy groups having 1 to 12 carbon atoms, aryl groups having 6 to 24 carbon atoms, halogen groups, and reactive functional groups, and R ¹ and R ² may be the same or different.

As long as the repeating units described above are contained within the above ranges, small amounts of branching units or crosslinking units represented by the following formulas (XII) to (XIV) may also be contained. The copolymerization amount of these branching units or crosslinking units is preferably in the range of 0 to 1 mol % per mole of -(Ar-S)- units.

Here, Ar is a unit selected from the units represented by formulas (I) to (XI).

The arylene sulfide unit may be a random copolymer, a block copolymer, or a mixture thereof containing the above repeating units.

Representative examples of these include polyphenylene sulfide, polyphenylene sulfide sulfone, polyphenylene sulfide ketone, their random copolymers, block copolymers, and mixtures thereof. Particularly preferred polyarylene sulfides contain p-phenylene sulfide units represented by the following formula (XV) as the main structural unit of the polymer.

Examples include polyphenylene sulfides containing 80 mol % or more, particularly 90 mol % or more.

The lower limit of the number average molecular weight Mn of the arylene sulfide units in the polyarylene sulfide copolymer that forms the polyarylene sulfide copolymer particles is preferably 1,000 or more, more preferably 1,500 or more, and even more preferably 2,000 or more. Having the number average molecular weight of the arylene sulfide units in the above range tends to provide high chemical resistance. The upper limit of the number average molecular weight of the arylene sulfide units is preferably 10,000 or less, more preferably 6,000 or less, and even more preferably 4,000 or less. Having the number average molecular weight of the arylene sulfide units in the above range tends to provide high heat resistance.

Here, the number average molecular weight of the arylene sulfide units in the polyarylene sulfide copolymer refers to the number average molecular weight of the portion of the polyarylene sulfide copolymer derived from the polyarylene sulfide (A) described below. The number average molecular weight of the arylene sulfide units in the polyarylene sulfide copolymer can be determined by measuring the molecular weight of the residue (corresponding to the arylene sulfide units) obtained by decomposing the linking groups of the polyarylene sulfide copolymer using the method described below. As a method for decomposing the linking groups, known methods depending on the type of linking group can be used. For example, if the linking group is an imide group, a method of decomposing polyimide can be used. The bonding groups can be decomposed by treating the polyarylene sulfide copolymer in an aqueous sodium hydroxide solution as described in JP 2006-124530 A, or by reacting the polyarylene sulfide copolymer in the presence of water or alcohol at high temperatures and pressures of 110°C or higher and 1 MPa or higher as described in JP 2001-163973 A.

In order to set the number average molecular weight of the arylene sulfide units in the polyarylene sulfide copolymer within the above range, it is preferable to use a polyarylene sulfide (A) having a number average molecular weight Mn of 1,000 or more and 10,000 or less, as described below, in the production of the polyarylene sulfide copolymer. The weight average molecular weight and number average molecular weight can be determined, for example, using SEC (size exclusion chromatography) equipped with a differential refractive index detector.

The polyarylene sulfide copolymer that forms the polyarylene sulfide copolymer particles contains, in addition to arylene sulfide units, structures derived from the copolymerization components. Examples of structures derived from the copolymerization components contained in the polyarylene sulfide copolymer include structures containing aromatic rings. Structures selected from the structures represented by formulas (a) to (s) above are preferred, and structures selected from the structures represented by formulas (a) to (e), (i), and (j) above are more preferred, with the structure represented by formula (i) being particularly preferred. The inclusion of these structures tends to result in sufficient mechanical properties, chemical resistance, and rigidity at high temperatures.

Here, R ³ , R ⁴ , and R ⁵ are substituents selected from hydrogen, alkyl groups having 1 to 12 carbon atoms, arylene groups having 6 to 24 carbon atoms, and halogen groups, and R ³ , R ⁴ , and R ⁵ may be the same or different.

In the polyarylene sulfide copolymer that forms the polyarylene sulfide copolymer particles, the arylene sulfide units and copolymerization components may be linked via a structure other than each repeating unit, or the end groups derived from the repeating units may be directly linked to each other. The arylene sulfide units and copolymerization components are preferably linked via at least one bonding group selected from sulfonyl groups, sulfinyl groups, ester groups, amide groups, imide groups, ether groups, urea groups, urethane groups, and siloxane groups. Of these, linking via an imide group is more preferred. Linking via an imide group tends to exhibit higher rigidity at high temperatures.

The lower limit of the amount of linking groups connecting the arylene sulfide units and copolymerization components is preferably 1 mol% or more, more preferably 2 mol% or more, and even more preferably 4 mol% or more, relative to the sulfur atoms contained in the polyarylene sulfide copolymer. By keeping the amount of linking groups within the above range, it tends to be possible to sufficiently suppress a decrease in rigidity under high-temperature conditions. The upper limit of the amount of linking groups is preferably 60 mol% or less, more preferably 40 mol% or less, even more preferably 30 mol% or less, and even more preferably 20 mol% or less. While a large amount of linking groups tends to decrease chemical resistance, keeping it within the above range tends to exhibit sufficient mechanical properties and chemical resistance. The amount of linking groups can be calculated using the amount of functional groups contained in the polyarylene sulfide (A) and the amount of functional groups contained in the compound (B), which are described below and are used in the production of the polyarylene sulfide copolymer, or it can be determined by measuring the FT-IR spectrum or NMR spectrum of the polyarylene sulfide copolymer particles.

The lower limit of the weight-average molecular weight of the polyarylene sulfide copolymer contained in the polyarylene sulfide copolymer particles is preferably 30,000 or more, more preferably 40,000 or more, and even more preferably 50,000 or more. If the weight-average molecular weight is less than 30,000, the mechanical properties of the polyarylene sulfide copolymer particles tend to be poor. There is no particular upper limit to the weight-average molecular weight, but preferred examples include 200,000 or less, more preferably 150,000 or less, and even more preferably 100,000 or less. When the upper limit of the weight-average molecular weight is within the above range, the polyarylene sulfide copolymer particles tend to have excellent moldability. The weight-average molecular weight can be determined, for example, using SEC (size exclusion chromatography) using a differential refractive index detector.

The lower limit of the median diameter D50 of the polyarylene sulfide copolymer particles is 1 μm or more. If D50 is less than 1 μm, the bulk density will be small, reducing handleability, and the particles will be so fine that they tend to adhere to a recoater, for example, during three-dimensional modeling, reducing handleability. The upper limit of D50 is 1000 μm. D50 is preferably 150 μm or less, more preferably 100 μm or less, even more preferably 70 μm or less, and most preferably 50 μm or less. If D50 exceeds 1000 μm, the particle size will exceed the stack height during three-dimensional modeling, resulting in a rough surface. Furthermore, when a resin composition is manufactured by blending fillers and/or other additives, a homogeneous resin composition cannot be obtained. From the viewpoint of obtaining molded products with smooth surfaces during three-dimensional modeling and obtaining a homogeneous resin composition during resin composition manufacturing, D50 is preferably 150 μm or less. The median diameter D50 is the particle size at which the cumulative frequency from the small particle size side of the particle size distribution measured with a laser diffraction particle size distribution analyzer is 50%. Polyarylene sulfide copolymer particles having a median diameter D50 of 1000 μm or less can be produced by the production method described below. The median diameter D50 can be adjusted, for example, by the type of solvent used to dissolve the polyarylene sulfide copolymer, the ratio of the polyarylene sulfide copolymer to the solvent, the cooling rate during precipitation of the polyarylene sulfide copolymer, stirring, etc.

The particle size distribution of polyarylene sulfide copolymer particles is preferably 10 or less, more preferably 7 or less, even more preferably 5 or less, even more preferably 4 or less, and even more preferably 3 or less. The particle size distribution is expressed as D90/D10, the ratio of D90 to D10, measured using a laser diffraction particle size distribution analyzer. Theoretically, the lower limit of D90/D10 is 1.0. By keeping the upper limit of D90/D10 within the above range, differences in melting properties due to differences in particle size tend to be reduced in three-dimensional modeling and resin composition production, resulting in more homogeneous models and resin compositions. D90/D10 is the particle size (D90) at which the cumulative frequency from the small particle size side of the particle size distribution measured using the laser diffraction particle size distribution analyzer described above is 90%, divided by the particle size (D10) at which the cumulative frequency from the small particle size side is 10%. Polyarylene sulfide copolymer particles having a D90/D10 ratio within the above range can be produced by the production method described below. Furthermore, D90/D10 can be adjusted, for example, by the cooling rate and stirring when precipitating the polyarylene sulfide copolymer particles.

The sphericity, which indicates the sphericity of the polyarylene sulfide copolymer particles, is 80 or more, and more preferably 90 or more. If the sphericity is less than 80, sufficient fluidity cannot be obtained during three-dimensional modeling, and the surface tends to become rough. Furthermore, when a resin composition is manufactured by blending fillers and/or other additives, it tends to be difficult to obtain a homogeneous resin composition. Furthermore, when the polyarylene sulfide copolymer particles are used as a dispersion, the viscosity of the dispersion tends to increase, making it difficult to handle. Theoretically, the upper limit of sphericity is 100, and any value below 100 is acceptable. The upper limit of sphericity is preferably 99 or less. The sphericity is calculated by observing the minor axis and major axis of 30 randomly selected particles in an optical microscope photograph of the polyarylene sulfide copolymer particles, and using the following formula:

In the formula, S is the sphericity, n is the number of measurements, a _i is the major axis of the i-th particle, and b _i is the minor axis of the i-th particle. The number of measurements, n, is 30. Polyarylene sulfide copolymer particles having a sphericity within the above range can be produced by the production method described below.

The surface smoothness and internal solidity of polyarylene sulfide copolymer particles can be expressed by the BET specific surface area determined by gas adsorption. When the resin particle surface is smooth and the particle interior is solid, the particle surface area is reduced, fluidity is improved, and the surface of the resulting shaped object is smoother, which is preferable. Here, the smaller the BET specific surface area, the smoother the surface. Specifically, the BET specific surface area is preferably 10 m ² /g or less, more preferably 5 m ² /g or less, even more preferably 3 m ² /g or less, particularly preferably 1 m ² /g or less, and most preferably 0.5 m ² /g or less. Theoretically, the lower limit is 0.05 m ² /g when the particle diameter is 100 μm.

The BET specific surface area can be measured in accordance with Japanese Industrial Standards (JIS) JIS R 1626 (1996) "Method for measuring specific surface area by the gas adsorption BET method."

The solidity of polyarylene sulfide copolymer particles can be evaluated by the ratio of BET specific surface area to theoretical specific surface area. The closer the ratio of BET specific surface area to theoretical specific surface area is to 1, the smoother the surface and the more solid the particles. The above ratio is preferably 5 or less, more preferably 4 or less, even more preferably 3 or less, and most preferably 2 or less. Theoretically, the lower limit is 1. Having the ratio of BET specific surface area to theoretical specific surface area in the above range is preferable because it can suppress the generation of voids when polyarylene sulfide copolymer particles are used to mold composite materials and exhibit excellent mechanical properties. It is also preferable because when used as a raw material for three-dimensional modeling using powder bed fusion, it suppresses the generation of voids inside and outside the three-dimensional model and exhibits excellent appearance and mechanical properties. The theoretical specific surface area can be expressed as the ratio of the surface area to the weight of a single sphere calculated from the D50 particle size and density of the polyarylene sulfide copolymer particles, assuming that the polyarylene sulfide copolymer particles are perfectly spherical.

It is preferable that the polyarylene sulfide copolymer particles of the present invention generate a small amount of organic gas when heated and melted. The polyarylene sulfide copolymer particles of the present invention can be used to obtain three-dimensional objects by lamination and melting, or to obtain reinforced fiber composite substrates with excellent mechanical properties and molded articles made therefrom by dispersing and melting the particles in reinforcing fibers. Both processes involve heating and melting the polyarylene sulfide copolymer particles, and it is preferable that the amount of organic gas is small from the perspective of preventing the incorporation of voids into the three-dimensional objects, reinforcing fiber composite substrates, and molded articles made therefrom, and from the perspective of ensuring worker safety. From the above perspectives, it is preferable that the polyarylene sulfide copolymer particles of the present invention are finally washed with water and then dried.

[Method for producing polyarylene sulfide copolymer]
The polyarylene sulfide copolymer used in the present invention is preferably produced by a method of heating polyarylene sulfide (A) having a number average molecular weight Mn of 1,000 or more and 10,000 or less, and at least one compound (B) selected from the formulae (a') to (u') (hereinafter, may be abbreviated as compound (B)).

wherein X is at least one group selected from two carboxyl groups bonded to two adjacent carbon atoms, or an acid anhydride group derived from the two carboxyl groups, an amino group, a hydroxyl group, a carboxyl group, a silanol group, a sulfonic acid group, an acetamide group, a sulfonamide group, a cyano group, an isocyanate group, an aldehyde group, an acetyl group, an epoxy group, and an alkoxysilyl group. R ³ , R ⁴ , and R ⁵ are each a substituent selected from hydrogen, an alkyl group having 1 to 12 carbon atoms, an arylene group having 6 to 24 carbon atoms, and a halogen group, and R ³ , R ⁴ , and R ⁵ may be the same or different.

[Polyarylene sulfide (A)]
The polyarylene sulfide (A) is a homopolymer or copolymer having a repeating unit represented by the formula -(Ar-S)- as a main structural unit. Here, "main structural unit" means that the repeating unit accounts for 70 mol % or more. Ar may be any of the units represented by the above formulas (I) to (XI), with the unit represented by formula (I) being particularly preferred.

As long as the repeating units described above are contained within the above ranges, small amounts of branching units or crosslinking units represented by the following formulas (XII) to (XIV) may also be contained. The copolymerization amount of these branching units or crosslinking units is preferably in the range of 0 to 1 mol % per mole of -(Ar-S)- units.

Polyarylene sulfide (A) may be a random copolymer, a block copolymer, or a mixture thereof containing the above repeating units.

Typical examples of these include polyphenylene sulfide, polyphenylene sulfide sulfone, polyphenylene sulfide ketone, their random copolymers, block copolymers, and mixtures thereof. Particularly preferred polyarylene sulfides include polyphenylene sulfides containing p-phenylene sulfide units represented by formula (XV) above as the main structural unit of the polymer, preferably at 80 mol % or more, and particularly preferably at 90 mol % or more.

Polyarylene sulfide (A) contains, as a functional group, at least one functional group selected from two carboxyl groups bonded to two adjacent carbon atoms, or an acid anhydride group derived from the two carboxyl groups, an amino group, a hydroxyl group, a carboxyl group, a silanol group, a sulfonic acid group, an acetamide group, a sulfonamide group, a cyano group, an isocyanate group, an aldehyde group, an acetyl group, an epoxy group, and an alkoxysilyl group. From the viewpoint of reactivity when polyarylene sulfide (A) is heated with compound (B) described below to produce a polyarylene sulfide copolymer, it is preferable that polyarylene sulfide (A) contains, as a functional group, at least one functional group selected from an amino group, two carboxyl groups bonded to two adjacent carbon atoms, and an acid anhydride group derived from the two carboxyl groups. Furthermore, from the viewpoint of reactivity, the combination of the functional group of the polyarylene sulfide (A) and the functional group of the compound (B) is preferably a combination of an amino group and an acid anhydride group, and therefore, the polyarylene sulfide (A) preferably contains an amino group and/or an acid anhydride group. In particular, from the viewpoint of ease of polymerization reaction when producing the polyarylene sulfide (A) by the production method described below, the functional group of the polyarylene sulfide (A) is preferably an amino group, and accordingly, the functional group of the compound (B) is preferably an acid anhydride group. The position of the functional group of the polyarylene sulfide (A) may be in the main chain of the polyarylene sulfide or at the terminal, but introduction at the terminal is preferred because it is easier to control the reaction with other polymers or compounds having functional groups, and is also preferred from the viewpoint of copolymerization reaction with the compound (B) as described below. When the functional group is introduced at the terminal, it is preferably in the p-position relative to the S bonded to Ar. In addition, polyarylene sulfides having the functional group bonded to Ar can also be exemplified as preferred embodiments. The above functional group is a structure derived from compound (C) described below, and details will be provided later.

The lower limit of the amount of functional groups contained in the polyarylene sulfide (A) is preferably 400 μmol/g or more, more preferably 500 μmol/g or more, and even more preferably 700 μmol/g or more. When the amount of functional groups is equal to or greater than the above lower limit, the glass transition temperature of the resulting polyarylene sulfide copolymer tends to be sufficiently high. Furthermore, the upper limit of the amount of functional groups is preferably 5,000 μmol/g or less, more preferably 4,000 μmol/g or less, and even more preferably 3,000 μmol/g or less. When the amount of functional groups is equal to or less than the above upper limit, a decrease in the chemical resistance of the polyarylene sulfide copolymer tends to be prevented when producing the polyarylene sulfide copolymer described below. Note that when the functional groups are two carboxyl groups bonded to two adjacent carbon atoms, respectively, the functional groups refer to the amount of acid anhydride groups generated from the two carboxyl groups bonded to two adjacent carbon atoms, respectively. The functional groups in the polyarylene sulfide can be quantified by subjecting the polyarylene sulfide to FT-IR analysis, for example, by comparing the intensity of the absorption at 3,382 cm ⁻¹ attributable to the amino group with the absorption at 1,901 m ⁻¹ attributable to the benzene ring, or the intensity of the absorption at 1,860 cm ⁻¹ attributable to the acid anhydride group with the absorption at 1,901 m ⁻¹ attributable to the benzene ring.

The number average molecular weight of polyarylene sulfide (A) is preferably 1,000 or more, more preferably 2,000 or more. When the number average molecular weight of polyarylene sulfide (A) is 1,000 or more, the chemical resistance of the resulting polyarylene sulfide copolymer is enhanced. The upper limit of the number average molecular weight of polyarylene sulfide (A) is preferably 10,000 or less, more preferably 6,000 or less, and even more preferably 4,000 or less. When the number average molecular weight of polyarylene sulfide is 10,000 or less, the heat resistance of the resulting polyarylene sulfide copolymer is enhanced. The number average molecular weight is a value calculated in terms of polystyrene using gel permeation chromatography (GPC), a type of size exclusion chromatography (SEC).

The method for producing polyarylene sulfide (A) is described in detail below, but is not limited to the following method. In the present invention, a method for producing polyarylene sulfide involves reacting at least a dihalogenated aromatic compound, an inorganic sulfidizing agent, and compound (C) in an organic polar solvent in the presence of an alkali metal hydroxide. Preferably, compound (C) is present in the reaction vessel in an amount of 0.04 mol to 0.5 mol per mol of inorganic sulfidizing agent. Compound (C) will be described later. Furthermore, when two carboxyl groups bonded to two adjacent carbon atoms or acid anhydride groups derived from these two carboxyl groups are selected as functional groups contained in polyarylene sulfide (A), employing a known method for producing polyarylene sulfide in which at least a dihalogenated aromatic compound, an inorganic sulfidizing agent, and a monohalogenated compound are reacted in an organic polar solvent in the presence of an alkali metal hydroxide is also effective from the standpoint of the reactivity of the monohalogenated compound, i.e., the ease of introducing functional groups into polyarylene sulfide (A). Examples of monohalogenated compounds used here include 3-chlorophthalic acid and 4-chlorophthalic acid.

[Inorganic sulfidizing agent]
The inorganic sulfidizing agent used in the production method of polyarylene sulfide (A) may be any agent capable of introducing a sulfide bond into a dihalogenated aromatic compound, and examples thereof include alkali metal sulfides, alkali metal hydrosulfides, and hydrogen sulfide.

Specific examples of alkali metal sulfides include lithium sulfide, sodium sulfide, potassium sulfide, rubidium sulfide, cesium sulfide, and mixtures of two or more of these. Of these, lithium sulfide and/or sodium sulfide are preferred, with sodium sulfide being more preferred. These alkali metal sulfides can be used as hydrates or aqueous mixtures, or in the anhydrous form. An 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. Generally available, inexpensive alkali metal sulfides are hydrates or aqueous mixtures, so it is preferable to use alkali metal sulfides in these forms.

Specific examples of alkali metal hydrosulfides include lithium hydrosulfide, sodium hydrosulfide, potassium hydrosulfide, rubidium hydrosulfide, cesium hydrosulfide, and mixtures of two or more of these. Of these, lithium hydrosulfide and/or sodium hydrosulfide are preferred, with sodium hydrosulfide being more preferred.

Alkali metal sulfides prepared in a reaction system from alkali metal hydrosulfide and alkali metal hydroxide can also be used. Alkali metal sulfides prepared in advance by bringing alkali metal hydrosulfide and alkali metal hydroxide into contact can also be used. These alkali metal hydrosulfides and alkali metal hydroxides can be used as hydrates, aqueous mixtures, or in the anhydrous form. Hydrates or aqueous mixtures are preferred from the standpoint of availability and cost.

In addition, alkali metal sulfides prepared in the reaction system from an alkali metal hydroxide such as lithium hydroxide or sodium hydroxide and hydrogen sulfide can also be used. It is also possible to use alkali metal sulfides prepared in advance by bringing an alkali metal hydroxide such as lithium hydroxide or sodium hydroxide into contact with hydrogen sulfide. Hydrogen sulfide may be used in any form, whether gaseous, liquid, or aqueous solution.

[Compound (C)]
The compound (C) used in the method for producing the polyarylene sulfide (A) is a compound having at least one aromatic ring, and having, on the one aromatic ring, at least one functional group selected from two carboxyl groups bonded to two adjacent carbon atoms, respectively, or an acid anhydride group derived from the two carboxyl groups, an amino group, a hydroxyl group, a carboxyl group, a silanol group, a sulfonic acid group, an acetamide group, a sulfonamide group, a cyano group, an isocyanate group, an aldehyde group, an acetyl group, an epoxy group, and an alkoxysilyl group, and at least one functional group selected from a hydroxyl group, a salt of a hydroxyl group, a thiol group, and a salt of a thiol group. At least one functional group selected from two carboxyl groups bonded to two adjacent carbon atoms, or an acid anhydride group derived from the two carboxyl groups, an amino group, a hydroxyl group, a carboxyl group, a silanol group, a sulfonic acid group, an acetamide group, a sulfonamide group, a cyano group, an isocyanate group, an aldehyde group, an acetyl group, an epoxy group, and an alkoxysilyl group, is introduced into the polyarylene sulfide (A) as a functional group in the polymerization reaction step. At least one functional group selected from a hydroxyl group, a salt of a hydroxyl group, a thiol group, and a salt of a thiol group reacts with a dihalogenated aromatic compound in the polymerization reaction step.

From the viewpoint of reactivity when polyarylene sulfide (A) is heated with compound (B), which will be described later, the functional group introduced into polyarylene sulfide (A) in compound (C) is preferably at least one functional group selected from an amino group, two carboxyl groups bonded to two adjacent carbon atoms, and an acid anhydride group derived from the two carboxyl groups, and more preferably an amino group and/or an acid anhydride group. Specific examples of compound (C) having such a functional group include 2-aminophenol, 4-aminophenol, 3-aminophenol, 2-aminothiophenol, 4-aminothiophenol, 3-aminothiophenol, 3-hydroxyphthalic acid, 4-hydroxyphthalic acid, 3-mercaptophthalic acid, 4-mercaptophthalic acid, and compounds in which the hydroxyl group or thiol group of these compounds is an alkali metal or alkaline earth metal salt. Among these, 4-aminophenol and 4-aminothiophenol are preferred from the viewpoint of reactivity. It should be noted that two or more different compounds (C) may be used in combination as long as they have the above characteristics. When a compound having a hydroxyl group or a thiol group is used as compound (C), a preferred embodiment is to simultaneously use an equal amount of an alkali metal hydroxide. Furthermore, when a compound in which the hydroxyl group or the thiol group is in the form of a salt is used as compound (C), the salt can be formed in advance and then used to produce polyarylene sulfide, or the salt can be formed by reaction in a reaction vessel.

The lower limit of the amount of compound (C) used in the polymerization reaction is preferably 0.01 mol or more per 1 mol of inorganic sulfidizing agent added, more preferably 0.02 mol or more, even more preferably 0.04 mol or more, even more preferably 0.05 mol or more, still more preferably 0.06 mol or more, even more preferably 0.08 mol or more, and particularly preferably 0.1 mol or more. An amount of use of this value or more is preferred because functional groups can be sufficiently introduced into polyarylene sulfide (A). Furthermore, the upper limit of the amount of compound (C) used is preferably 0.5 mol or less per 1 mol of inorganic sulfidizing agent added, more preferably 0.45 mol or less, and even more preferably 0.4 mol or less. An amount of use of this value or less is preferred because a decrease in the molecular weight of polyarylene sulfide (A) can be prevented.

There is no particular restriction on the timing of adding compound (C), and it may be added at any time during the pre-processing step described below, at the start of polymerization, or during the polymerization reaction step, or it may be added in multiple batches. However, from the perspective of efficiently reacting with the dihalogenated aromatic compound, it is more preferable to add it at the same stage as the dihalogenated aromatic compound is added to the reaction vessel.

[Dihalogenated aromatic compound]
Examples of dihalogenated aromatic compounds used in the production method of polyarylene sulfide (A) include dihalogenated benzenes such as p-dichlorobenzene, o-dichlorobenzene, m-dichlorobenzene, p-dibromobenzene, o-dibromobenzene, m-dibromobenzene, 1-bromo-4-chlorobenzene, and 1-bromo-3-chlorobenzene, as well as dihalogenated aromatic compounds including compounds having substituents other than halogen, such as 1-methoxy-2,5-dichlorobenzene, 1-methyl-2,5-dichlorobenzene, 1,4-dimethyl-2,5-dichlorobenzene, 1,3-dimethyl-2,5-dichlorobenzene, 2,5-dichlorobenzoic acid, 3,5-dichlorobenzoic acid, 2,5-dichloroaniline, 3,5-dichloroaniline, and bis(4-chlorophenyl)sulfide. Among these, dihalogenated aromatic compounds containing p-dihalogenated benzenes, typified by p-dichlorobenzene, as the main component are preferred. Particularly preferably, the dihalogenated aromatic compound contains p-dichlorobenzene in an amount of 80 to 100 mol %, and even more preferably 90 to 100 mol %. It is also possible to use a combination of two or more different dihalogenated aromatic compounds.

Although there is no particular lower limit to the amount of dihalogenated aromatic compound used, the [monomer ratio] expressed by the following formula is preferably 0.8 or more, more preferably 0.9 or more, and even more preferably 0.95 or more. By setting the [monomer ratio] within the above range, the polymerization reaction system can be stabilized and side reactions can be prevented, which is preferable. Furthermore, there is no particular upper limit to the amount used, but the [monomer ratio] is preferably 1.2 or less, more preferably 1.1 or less, and even more preferably 1.05 or less. By setting the [monomer ratio] within the above range, the amount of halogen remaining in the polyarylene sulfide can be reduced, which is preferable. In the following formula, the [dihalogenated aromatic compound substance amount], [inorganic sulfidizing agent substance amount], and [compound (C) substance amount] indicate the amount (mol) of each compound used when producing polyarylene sulfide.
[Monomer ratio]=[amount of dihalogenated aromatic compound]/([amount of inorganic sulfidizing agent]+[amount of compound (C)]).

[Organic polar solvent]
Preferred examples of organic polar solvents include organic amide solvents. Specific examples include N-alkylpyrrolidones such as N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, and N-cyclohexyl-2-pyrrolidone; caprolactams such as N-methyl-ε-caprolactam; aprotic organic solvents such as 1,3-dimethyl-2-imidazolidinone, N,N-dimethylacetamide, N,N-dimethylformamide, and hexamethylphosphoric triamide; and mixtures thereof, which are preferably used due to their high reaction stability. Among these, N-methyl-2-pyrrolidone and 1,3-dimethyl-2-imidazolidinone are preferred, and N-methyl-2-pyrrolidone is more preferred.

The amount of organic polar solvent used is preferably 2.0 moles or more, more preferably 2.2 moles or more, and even more preferably 2.3 moles or more, per mole of inorganic sulfidizing agent charged. Amounts of this value or more are preferred because polyarylene sulfide can be synthesized in good yield. Furthermore, the amount of organic polar solvent used is preferably 6.0 moles or less, more preferably 5.0 moles or less, and even more preferably 4.0 moles or less, per mole of inorganic sulfidizing agent charged. Amounts of this value or less are preferred because they reduce the amount of gas generated when the resulting polyarylene sulfide is heated.

[Polymerization aid]
In order to obtain a polyarylene sulfide with a relatively high degree of polymerization in a shorter time, it is also a preferred embodiment to use a polymerization aid. Here, the polymerization aid refers to a substance that has the effect of increasing the viscosity of the resulting polyarylene sulfide. Specific examples of such polymerization aids include organic carboxylates, water, alkali metal chlorides, organic sulfonates, alkali metal sulfates, alkaline earth metal oxides, alkali metal phosphates, and alkaline earth metal phosphates. These may be used alone or in combination of two or more. Among these, organic carboxylates, water, and alkali metal chlorides are preferred, and alkali metal carboxylates are preferred as organic carboxylates, and lithium chloride is preferred as alkali metal chlorides.

The alkali metal carboxylate is a compound represented by the general formula R(COOM) _n (wherein R is an alkyl group, cycloalkyl group, aryl group, alkylaryl group, or arylalkyl group having 1 to 20 carbon atoms; M is an alkali metal selected from lithium, sodium, potassium, rubidium, and cesium; and n is an integer of 1 to 3). The alkali metal carboxylate can also be used as a hydrate, anhydrous form, or aqueous solution. Specific examples of the alkali metal carboxylate include lithium acetate, sodium acetate, potassium acetate, sodium propionate, lithium valerate, sodium benzoate, and mixtures thereof.

Alkali metal carboxylates may be synthesized by adding and reacting an organic acid with one or more compounds selected from the group consisting of alkali metal hydroxides, alkali metal carbonates, and alkali metal bicarbonates in approximately equal chemical equivalents. Of the alkali metal carboxylates listed above, lithium salts are highly soluble in the reaction system and have a significant auxiliary effect, but are expensive. On the other hand, potassium, rubidium, and cesium salts are thought to have insufficient solubility in the reaction system, so sodium acetate, which is inexpensive and has adequate solubility in the polymerization system, is most preferably used.

When these alkali metal carboxylates are used as polymerization aids, the amount used is usually preferably in the range of 0.01 to 2 moles per mole of inorganic sulfidizing agent charged, more preferably in the range of 0.1 to 0.6 moles in order to obtain a higher degree of polymerization, and even more preferably in the range of 0.2 to 0.5 moles.

When water is used as a polymerization aid, the amount added is usually preferably in the range of 0.3 to 15 moles per mole of inorganic sulfidizing agent charged, more preferably in the range of 0.6 to 10 moles in order to obtain a higher degree of polymerization, and even more preferably in the range of 1 to 5 moles.

It is of course possible to use two or more of these polymerization aids in combination; for example, using an alkali metal carboxylate in combination with water makes it possible to achieve a high molecular weight with smaller amounts of alkali metal carboxylate and water.

There is no particular requirement for the timing of addition of these polymerization aids; they may be added at any time during the pre-processing step described below, at the start of polymerization, or during the polymerization reaction step, or they may be added in multiple batches. When using an alkali metal carboxylate as the polymerization aid, it is preferable to add it at the start of the pre-processing step or at the start of polymerization simultaneously with other additives, as this makes addition easier. Furthermore, when using water as the polymerization aid, it is effective to add it midway through the polymerization reaction step after charging the dihalogenated aromatic compound.

[Polymerization stabilizer]
Polymerization stabilizers can be used to stabilize the polymerization reaction system and prevent side reactions. Polymerization stabilizers contribute to stabilizing the polymerization reaction system and suppress undesirable side reactions. One indicator of side reactions is the formation of thiophenol. The addition of a polymerization stabilizer can suppress the formation of thiophenol. Specific examples of polymerization stabilizers include compounds such as alkali metal hydroxides, alkali metal carbonates, alkaline earth metal hydroxides, and alkaline earth metal carbonates. Among these, alkali metal hydroxides such as sodium hydroxide, potassium hydroxide, and lithium hydroxide are preferred. The aforementioned alkali metal carboxylates also function as polymerization stabilizers and are therefore classified as polymerization stabilizers. Furthermore, when using alkali metal hydrosulfides as inorganic sulfidizing agents, it is particularly preferable to use alkali metal hydroxides simultaneously. However, alkali metal hydroxides in excess of the sulfidizing agent can also function as polymerization stabilizers.

These polymerization stabilizers can be used alone or in combination of two or more. The polymerization stabilizer is preferably used in an amount of 0.02 to 0.2 moles per mole of inorganic sulfidizing agent charged, more preferably 0.03 to 0.1 moles, and even more preferably 0.04 to 0.09 moles. If this ratio is too low, the stabilizing effect will be low, and conversely, if it is too high, it will be economically disadvantageous and the polymer yield will tend to decrease.

There is no particular requirement for the timing of adding the polymerization stabilizer; it may be added at any time during the pre-process, at the start of polymerization, or during the polymerization reaction process, as described below. It may also be added in multiple batches, but it is preferable to add it simultaneously at the start of the pre-process or at the start of polymerization, as this is easier.

Next, a preferred method for producing polyarylene sulfide will be specifically explained in order, including the pre-process, polymerization reaction process, recovery process, and post-treatment process, but the method is not limited to this.

[Pre-process]
In the method for producing polyarylene sulfide (A), the inorganic sulfidizing agent is usually used in the form of a hydrate. Before adding the dihalogenated aromatic compound, it is preferable to heat the mixture containing the organic polar solvent and the inorganic sulfidizing agent and remove excess water from the system.

As mentioned above, inorganic sulfidizing agents can also be used that are prepared in situ in the reaction system from alkali metal hydrosulfide and alkali metal hydroxide, or in a vessel separate from the polymerization vessel. There are no particular limitations on this method, but a preferred method involves adding alkali metal hydrosulfide and alkali metal hydroxide to an organic polar solvent in an inert gas atmosphere at a temperature ranging from room temperature to 150°C, preferably from room temperature to 100°C, and then heating the mixture to at least 150°C or higher, preferably 180°C to 260°C, under atmospheric or reduced pressure, to distill off water. At this stage, a polymerization aid or compound (C) may be added. Toluene or the like may also be added to facilitate the distillation of water during the reaction.

At the end of the previous step, i.e., before the polymerization reaction step, the amount of water in the system is preferably 0.3 to 10.0 moles per mole of charged sulfidizing agent. Here, the amount of water in the system is the amount of water charged to the polymerization system minus the amount of water removed from the polymerization system. The charged water may be in any form, such as water, an aqueous solution, or water of crystallization.

[Polymerization reaction step]
Polyarylene sulfide (A) is produced by reacting at least an inorganic sulfidizing agent, a dihalogenated aromatic compound, and compound (C) in an organic polar solvent within a temperature range of 200°C or higher but lower than 290°C.

When starting the polymerization reaction process, the organic polar solvent, sulfidizing agent, and dihalogenated aromatic compound are mixed, preferably in an inert gas atmosphere, at a temperature ranging from room temperature to 240°C, and preferably from 100°C to 230°C. Compound (C) and a polymerization aid may also be added at this stage. These raw materials may be added in any order, or simultaneously.

This mixture is typically heated to a temperature in the range of 200°C to less than 290°C. There are no particular restrictions on the heating rate, but a rate of 0.01°C/min to 5°C/min is usually selected, with a range of 0.1°C/min to 3°C/min being more preferred.

Generally, the temperature is finally raised to between 250°C and 290°C, and the reaction is carried out at that temperature for typically 0.25 hours to 50 hours, preferably 0.5 hours to 20 hours.

Before reaching the final temperature, a method of reacting for a certain period of time at, for example, 200°C to 260°C, and then raising the temperature to 270°C to less than 290°C is effective in achieving a higher degree of polymerization. In this case, the reaction time at 200°C to 260°C is usually selected to be in the range of 0.25 to 20 hours, preferably 0.25 to 10 hours.

In order to adjust the molecular weight of the polymer, compound (C) can be added during the polymerization. However, from the viewpoint of efficient reaction of compound (C), it is more preferable to add at least a portion of compound (C) at the same stage as the dihalogenated aromatic compound.

[Recovery process]
In the method for producing the polyarylene sulfide (A), after the polymerization is completed, a solid is recovered from the polymerization reaction product containing the polymer, the solvent, etc. Any known method may be used for the recovery method.

For example, after the polymerization reaction is complete, the mixture may be slowly cooled to recover the particulate polymer. There are no particular restrictions on the cooling rate, but it is usually around 0.1°C/min to 3°C/min. It is not necessary to cool at the same rate throughout the entire cooling process; instead, it is possible to use a method in which the mixture is slowly cooled at a rate of 0.1°C/min to 1°C/min until the polymer particles crystallize and precipitate, and then at a rate of 1°C/min or faster.

Another preferred method is to carry out the above recovery under rapid cooling conditions. Among these recovery methods, a preferred one is the flash method. The flash method is a method in which the polymerization reaction product is flashed from a high-temperature, high-pressure state (usually 250°C or higher, 8 kg/cm2 or ^higher ) into an atmosphere of normal pressure or reduced pressure, and the polymer is recovered in powder form while the solvent is recovered. The term "flash" as used herein means that the polymerization reaction product is ejected from a nozzle. Specific examples of the flashing atmosphere include nitrogen or water vapor at normal pressure, and the temperature is usually selected from the range of 150°C to 250°C.

[Post-processing process]
After the polyarylene sulfide is produced through the above-mentioned polymerization reaction step and recovery step, it can be subjected to a post-treatment step of acid treatment, hot water treatment, or washing with an organic solvent. From the viewpoint of removing impurities, the post-treatment step is preferably any one of acid treatment, hot water treatment, and washing with an organic solvent, and more preferably two or more of these treatments are used in combination.

When acid treatment is performed, the procedure is as follows. The acid used in the acid treatment is not particularly limited as long as it does not have the effect of decomposing polyarylene sulfide (A), and examples include acetic acid, hydrochloric acid, sulfuric acid, phosphoric acid, silicic acid, carbonic acid, and propylic acid. Among these, acids selected from acetic acid and hydrochloric acid are more preferably used. On the other hand, acids that decompose or deteriorate polyarylene sulfide (A), such as nitric acid, are not preferred. Examples of acid treatment methods include immersing polyarylene sulfide (A) in an acid or an aqueous solution of an acid, with stirring or heating possible if necessary. When an acid solution is used, the solution may be either an organic solvent solution or an aqueous solution, but an aqueous solution is preferred from the viewpoints of the miscibility of the acid and the tendency for the solubility of salts and basic components contained in polyarylene sulfide to be relatively high. The water used is preferably distilled water or deionized water so as not to impair the desired chemical modification effect of polyarylene sulfide. For example, when using acetic acid, a sufficient effect can be obtained by immersing the polyarylene sulfide (A) powder in an aqueous acetic acid solution of pH 4 heated to 80°C to 200°C and stirring for 30 minutes. The pH after treatment may be 4 or higher, for example, about pH 4 to 8. To remove any acid or salt remaining in the acid-treated polyarylene sulfide (A), it is preferable to further wash the polyarylene sulfide (A) several times with water or warm water. The water used for washing is preferably distilled water or deionized water so as not to impair the desired chemical modification effect of the polyarylene sulfide (A). Acid treatment is preferred because it tends to produce a polyarylene sulfide copolymer with a higher molecular weight when using the polyarylene sulfide (A) to obtain a polyarylene sulfide copolymer.

When hot water treatment is performed, the procedure is as follows: When hot water treatment of polyarylene sulfide (A), it is preferable that the temperature of the hot water is 100°C or higher, more preferably 120°C or higher, even more preferably 150°C or higher, and particularly preferably 170°C or higher. Temperatures below 100°C are not preferable because the desired chemical modification effect of polyarylene sulfide is small. In order to achieve the desired chemical modification effect of polyarylene sulfide (A) by hot water treatment, it is preferable that the water used is distilled water or deionized water. There are no particular restrictions on the hot water treatment procedure. It can be performed by adding a predetermined amount of polyarylene sulfide (A) to a predetermined amount of water and heating and stirring in a pressure vessel, or by performing hot water treatment continuously. The ratio of polyarylene sulfide (A) to water is preferably higher, but a bath ratio (weight of washing solution relative to weight of dry polyarylene sulfide (A)) of 200 g or less per liter of water is usually selected. Furthermore, to avoid undesirable decomposition of reactive terminal functional groups, it is desirable to perform the treatment in an inert atmosphere. Furthermore, to remove any remaining components, it is preferable to wash the polyarylene sulfide (A) several times with warm water after this hot water treatment.

When washing with an organic solvent, the procedure is as follows: There are no particular restrictions on the organic solvent used to wash polyarylene sulfide (A), as long as it does not have the effect of decomposing polyarylene sulfide. Examples of organic solvents that can be used to wash polyarylene sulfide (A) include nitrogen-containing polar solvents such as N-methyl-2-pyrrolidone, dimethylformamide, and dimethylacetamide; sulfoxide/sulfone solvents such as dimethyl sulfoxide, dimethyl sulfone, and sulfolane; ketone solvents such as acetone, methyl ethyl ketone, diethyl ketone, and acetophenone; ether solvents such as dimethyl ether, dipropyl ether, dioxane, and tetrahydrofuran; halogenated solvents such as chloroform, methylene chloride, trichloroethylene, ethylene dichloride, and perchloroethylene; alcohol solvents such as methanol, ethanol, propanol, butanol, pentanol, ethylene glycol, and propylene glycol; and aromatic hydrocarbon solvents such as benzene, toluene, and xylene. Among these organic solvents, N-methyl-2-pyrrolidone, acetone, dimethylformamide, chloroform, and the like are preferred. Furthermore, from the viewpoint of removing impurities having an arylene sulfide structure, solvents selected from N-methyl-2-pyrrolidone, dimethylformamide, and chloroform, which are nitrogen-containing polar solvents that tend to provide relatively high solubility, are particularly preferred. These organic solvents may be used alone or in combination with two or more, or may be mixed with water. Examples of methods for washing with an organic solvent include immersing the polyarylene sulfide (A) in the organic solvent, with appropriate stirring or heating as necessary. The washing temperature when washing the polyarylene sulfide (A) with an organic solvent is not particularly limited, and any temperature from room temperature to approximately 300°C can be selected. While higher washing temperatures tend to increase the washing efficiency, a washing temperature of room temperature to 150°C is usually sufficient. Washing can also be performed under pressure in a pressure vessel at a temperature above the boiling point of the organic solvent. The washing time is also not particularly limited. Although it depends on the washing conditions, in the case of batch washing, washing for 5 minutes or more usually produces sufficient results. Continuous washing is also possible. An organic solvent is preferred because it reduces the amount of gas generated when polyarylene sulfide (A) is heated, and also tends to make it easier to obtain a high-molecular-weight product when using polyarylene sulfide (A) to produce a polyarylene sulfide copolymer, as described below.

[Thermal oxidation crosslinking treatment]
The polyarylene sulfide (A) can be used after being polymerized by a thermal oxidation crosslinking treatment such as heating in an oxygen atmosphere or heating with a crosslinking agent such as a peroxide added thereto, but the number average molecular weight of the polyarylene sulfide (A) is preferably 10,000 or less.

[Compound (B)]
The compound (B) is a compound for producing a polyarylene sulfide copolymer by reacting it with the polyarylene sulfide (A).
Compound (B) is at least one compound selected from the formulae (a') to (u'). X is at least one selected from two carboxyl groups bonded to two adjacent carbon atoms, or an acid anhydride group derived from the two carboxyl groups, an amino group, a hydroxyl group, a carboxyl group, a silanol group, a sulfonic acid group, an acetamide group, a sulfonamide group, a cyano group, an isocyanate group, an aldehyde group, an acetyl group, an epoxy group, and an alkoxysilyl group. R ³ , R ⁴ , and R ⁵ are each a substituent selected from hydrogen, an alkyl group having 1 to 12 carbon atoms, an arylene group having 6 to 24 carbon atoms, and a halogen group, and R ³ , R ⁴ , and R ⁵ may be the same or different. From the perspective of ease of availability, hydrogen, a methyl group, an ethyl group, or a propyl group is preferred. Furthermore, the aromatic ring of each compound may be di- or tri-substituted, and the multiple substituents X substituted on one aromatic ring may be the same or different. From the viewpoint of reactivity when the above-mentioned polyarylene sulfide (A) and compound (B) are heated, it is preferable that compound (B) contains at least one functional group selected from an amino group, two carboxyl groups bonded to two adjacent carbon atoms, and an acid anhydride group derived from the two carboxyl groups. Furthermore, from the viewpoint of reactivity, the combination of the functional group of polyarylene sulfide (A) and the functional group of compound (B) is more preferably an amino group and an acid anhydride group, and therefore compound (B) more preferably contains an amino group and/or an acid anhydride group. In particular, from the viewpoint of ease of polymerization reaction when producing polyarylene sulfide (A) by the above-mentioned production method, it is preferable that the functional group of polyarylene sulfide (A) is an amino group, and accordingly, it is preferable that the functional group of compound (B) is an acid anhydride group.

Specific examples of compound (B) include pyromellitic acid, 3,3',4,4'-thiodiphthalic acid, 3,3',4,4'-sulfonyldiphthalic acid, 3,3',4,4'-benzophenonetetracarboxylic acid, 3,3',4,4'-sulfinyldiphthalic acid, 3,3',4,4'-biphenyltetracarboxylic acid, 3,3',4,4'-tetracarboxyldiphenylmethane, 9,9-bis(3,4-dicarboxyphenyl)fluorene, naphthalene-1,4,5,8-tetracarboxylic acid, and bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic acid. , 3,4,9,10-perylenetetracarboxylic acid, pyromellitic anhydride, 3,3',4,4'-thiodiphthalic anhydride, 3,3',4,4'-sulfonyldiphthalic anhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 3,3',4,4'-sulfinyldiphthalic anhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-tetracarboxylicdiphenylmethane dianhydride, 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride, naphthalene-1,4,5,8-tetracarboxylic dianhydride Water, glycerin bisanhydrotrimellitate monoacetate, ethylene glycol bisanhydrotrimellitate, bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, 4,4'-thiodibenzoic acid, 4,4'-dicarboxylbenzophenone, 4,4'-sulfinyldibenzoic acid, 4,4'-dicarboxylbiphenyl, p-phenylenediamine, 4,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfone, 4,4'-diaminobenzyl Examples of such benzophenone include 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ether, 2,7-diaminofluorene, o-toluidine, 1,5-diaminonaphthalene, p-benzenediol, 4,4'-dihydroxydiphenyl sulfide, 4,4'-dihydroxydiphenyl sulfone, 4,4'-dihydroxybenzophenone, 4,4'-dihydroxydiphenylmethane, 4,4'-dihydroxydiphenyl ether, 2,7-dihydroxyfluorene, 4,4'-dihydroxybiphenyl, and 1,5-dihydroxynaphthalene. From the standpoint of reactivity, compounds selected from 3,3',4,4'-thiodiphthalic anhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 3,3',4,4'-sulfinyldiphthalic anhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride, 4,4'-thiodibenzoic acid, 4,4'-dicarboxylbenzophenone, 4,4'-sulfinyldibenzoic acid, 4,4'-dicarboxylbiphenyl, pyromellitic acid, pyromellitic anhydride, 4,4'-diaminodiphenyl sulfone, 4,4'-diaminobenzophenone, and 2,7-diaminofluorene are preferably used.

[Production of polyarylene sulfide copolymer]
The polyarylene sulfide copolymer can be produced by heating the polyarylene sulfide (A) and the compound (B).

The ratio of the amount of functional groups derived from compound (B) [μmol/g] to the amount of functional groups derived from polyarylene sulfide (A) [μmol/g] is preferably 0.75 or more and 1.25 or less. By keeping it in this range, the resulting polyarylene sulfide copolymer tends to have a high molecular weight and exhibit sufficient mechanical properties and chemical resistance.

The polyarylene sulfide (A) and compound (B) may be heated by mixing the entire amount from the beginning, or by mixing and heating at least a portion of the polyarylene sulfide (A) and at least a portion of the compound (B) and then mixing and heating the remaining polyarylene sulfide (A) and/or compound (B). In the latter case, at least a portion of the polyarylene sulfide (A) and at least a portion of the compound (B) may be mixed and heated, and then the remaining polyarylene sulfide (A) and/or compound (B) may be mixed and heated. Alternatively, at least a portion of the polyarylene sulfide (A) and at least a portion of the compound (B) may be mixed and heated, and the product may be removed, and then the remaining polyarylene sulfide (A) and/or compound (B) may be mixed and heated. From the viewpoint of efficiently obtaining a polyarylene sulfide copolymer, it is preferable to mix and heat the entire amount of the polyarylene sulfide (A) and compound (B) from the beginning. On the other hand, from the viewpoint of easily controlling and adjusting the thermal properties of the polyarylene sulfide copolymer, such as the glass transition temperature, crystallization temperature, and melting point, as well as the molecular weight, the terminal type and amount depending on the application, it is preferable to mix and heat at least a portion of the polyarylene sulfide (A) and at least a portion of the compound (B), and then mix and heat the remaining polyarylene sulfide (A) and/or compound (B).

The lower limit of the heating temperature can be, for example, 200°C or higher, preferably 230°C or higher, and more preferably 250°C or higher. By setting the lower limit of the heating temperature in this range, the reaction between the polyarylene sulfide (A) and the compound (B) can be easily promoted. Setting the heating temperature to a temperature higher than the melting point of the polyarylene sulfide (A) tends to complete the reaction in a shorter time. The melting point of the polyarylene sulfide (A) cannot be uniquely determined because it varies depending on the composition and molecular weight of the polyarylene sulfide (A) and the heating environment. However, it can be determined, for example, by analyzing the polyarylene sulfide (A) with a differential scanning calorimeter. The upper limit of the heating temperature can be, for example, 400°C or lower, preferably 380°C or lower, and more preferably 360°C or lower. Setting the upper limit of the heating temperature within this range tends to suppress undesirable side reactions, such as crosslinking reactions and decomposition reactions between polyarylene sulfides (A), and to suppress deterioration in the properties of the resulting polyarylene sulfide copolymer.

The heating time cannot be specified uniquely because it varies depending on the composition and molecular weight of the polyarylene sulfide (A) and the heating environment, but it is preferable to set it so as to minimize the occurrence of the undesirable side reactions described above. The lower limit of the heating time can be, for example, 0.1 minutes or more, with 1 minute or more being preferred, 2 minutes or more being more preferred, and 3 minutes or more being even more preferred. By setting the lower limit of the heating time in this range, the reaction between the polyarylene sulfide (A) and the compound (B) can be more fully promoted. The upper limit of the heating time can be, for example, 100 hours or less, with 20 hours or less being preferred, 10 hours or less being more preferred, and 1 hour or less being even more preferred. Setting the upper limit of the heating time in this range is economical and tends to avoid the undesirable side reactions described above.

Heating can be carried out in the absence or presence of a solvent. When heating is carried out in the presence of a solvent, there are no particular restrictions on the solvent, so long as it does not substantially cause undesirable side reactions such as decomposition or crosslinking of the resulting polyarylene sulfide copolymer. One type of solvent or a mixture of two or more types can be used. On the other hand, from the perspective of efficiently obtaining the polyarylene sulfide copolymer, heating under substantially solvent-free conditions is preferable. Furthermore, from the perspective of preventing contamination of molded products by evolved gases when molding the resulting polyarylene sulfide copolymer, heating under substantially solvent-free conditions is also preferable. Here, substantially solvent-free conditions refer to a system in which the polyarylene sulfide (A) and compound (B) are heated, with the solvent content being 10% by weight or less, preferably 3% by weight or less.

In the method for producing the polyarylene sulfide copolymer of the present invention, heating can be carried out using a conventional polymerization reaction apparatus, or it can be carried out in a mold for producing a molded product, or it can be carried out using an extruder or melt kneader. There are no particular restrictions on the method as long as it uses equipment equipped with a heating mechanism, and known methods such as batch and continuous methods can be used.

The heating atmosphere is preferably a non-oxidizing atmosphere, and it is also preferable to carry out the heating under reduced pressure conditions. Furthermore, when carrying out the heating under reduced pressure conditions, it is preferable to first change the atmosphere in the reaction system to a non-oxidizing atmosphere and then to a reduced pressure condition. This tends to suppress undesirable side reactions such as crosslinking reactions and decomposition reactions between polyarylene sulfides (A) or between the resulting polyarylene sulfide copolymers. A non-oxidizing atmosphere refers to an atmosphere in which the oxygen concentration in the gas phase is 5% by volume or less, preferably 2% by volume or less, and more preferably an atmosphere that is substantially free of oxygen, i.e., an inert gas atmosphere such as nitrogen, helium, or argon. Among these, a nitrogen atmosphere is particularly preferable from the standpoint of economy and ease of handling. Furthermore, reduced pressure conditions refer to a system in which the reaction is carried out at a pressure lower than atmospheric pressure, with the upper limit of the pressure being preferably 50 kPa or less, more preferably 20 kPa or less, and even more preferably 10 kPa or less. Setting the upper limit of the pressure within this range tends to suppress undesirable side reactions such as crosslinking reactions. An example of a lower limit of the pressure is 0.1 kPa or more. By setting the lower pressure limit to 0.1 kPa or higher, it is possible to avoid putting strain on the reactor due to reducing the pressure more than necessary.

[Method for producing polyarylene sulfide copolymer particles]
The polyarylene sulfide copolymer particles can be produced by a process including step 1 of melt-kneading the polyarylene sulfide copolymer and the water-soluble thermoplastic resin, and step 2 of removing the water-soluble thermoplastic resin by washing with water or an alcohol.

[Step 1]
[Water-soluble thermoplastic resin]
The method for producing polyarylene sulfide copolymer particles of the present invention uses a water-soluble thermoplastic resin. While there are no limitations on the water-soluble thermoplastic resin, specific examples include polyalkylene glycol, polyvinyl alcohol, polyvinylpyrrolidone, polyamide, and polyamideimide, with polyalkylene glycol being preferred. In the present invention, the use of a water-soluble thermoplastic resin allows the use of water or alcohols in the cleaning process described below, thereby preventing worker exposure to organic solvents. It is also preferred because it reduces the release of chemical substances into the environment. The water-soluble thermoplastic resin preferably has a 10% weight loss temperature of 300°C or higher. A 10% weight loss temperature of 300°C or higher is preferred because it reduces the amount of decomposition gas during the melt-kneading process with the polyarylene sulfide copolymer. The 10% weight loss temperature can be analyzed, for example, by thermogravimetry under a nitrogen gas flow. Examples of polymers with a 10% weight loss temperature of 300°C or higher include polyalkylene glycol and polyvinylpyrrolidone. Furthermore, the water-soluble thermoplastic resin is preferably incompatible with the polyarylene sulfide copolymer during melt-kneading. Incompatibility refers to a state in which the two resins are not completely mixed at the molecular level, even if they appear to be kneaded at the macro level. Incompatibility between the water-soluble thermoplastic resin and the polyarylene sulfide copolymer is preferable because, for example, when the resin composition is washed with water or alcohols, the water-soluble thermoplastic resin is easily separated and removed, thereby obtaining polyarylene sulfide copolymer microparticles. When the water-soluble thermoplastic resin is compatible with the polyarylene sulfide copolymer, the two are integrated within the resin composition, and polyarylene sulfide copolymer microparticles cannot be obtained even when washed with water or alcohols. Whether or not they become incompatible depends on the kneading conditions and the composition of the polyarylene sulfide copolymer, so it is difficult to generalize. However, polyalkylene glycols are an example of a water-soluble thermoplastic resin that is likely to be incompatible with the polyarylene sulfide copolymer.

There are no particular restrictions on the form of the polyarylene sulfide copolymer used as the raw material for the polyarylene sulfide copolymer particles of the present invention, and examples include powder, pellets, fibers, films, molded products, and granules. Generally, dry grinding, wet grinding, and freeze grinding using jet mills, bead mills, hammer mills, ball mills, cutter mills, stone-type grinders, etc. are known as methods for micronizing resins. However, when pellets or molded products are used as the raw material, these methods can result in insufficient micronization, making it impossible to obtain particles of the desired particle size, or require long grinding times, resulting in reduced economic efficiency and productivity. However, the present method makes it possible to easily produce particles even when pellets or molded products are used as the raw material.

The lower limit of the glass transition point of the polyarylene sulfide copolymer used to produce the polyarylene sulfide copolymer particles of the present invention is 95°C or higher, preferably 100°C or higher, and more preferably 110°C or higher. If the glass transition point is below 95°C, high rigidity cannot be obtained under high-temperature conditions. The upper limit of the glass transition point is 190°C or lower, preferably 180°C or lower, and more preferably 160°C or lower. If the glass transition point exceeds 190°C, chemical resistance will be insufficient.

The glass transition points of the raw material polyarylene sulfide copolymer and polyarylene sulfide copolymer particles may vary depending on the conditions for producing polyarylene sulfide copolymer microparticles. The glass transition point of the polyarylene sulfide copolymer or polyarylene sulfide copolymer particles is defined as the inflection point of the baseline shift detected when the temperature is raised from 0°C to 340°C at a rate of 20°C/min using a differential scanning calorimeter using the method described below.

The lower limit of the weight-average molecular weight of the polyarylene sulfide copolymer used to produce the polyarylene sulfide copolymer particles of the present invention is preferably 30,000 or more, more preferably 40,000 or more, and even more preferably 50,000 or more. A weight-average molecular weight of 30,000 or more tends to improve the mechanical properties of the polyarylene sulfide copolymer microparticles. There is no particular upper limit to the molecular weight of the polyarylene sulfide copolymer particles, but examples include a weight-average molecular weight of 200,000 or less, with 150,000 or less being preferred and 100,000 or less being more preferred. Having an upper limit for the weight-average molecular weight within the above range tends to improve the moldability of the polyarylene sulfide copolymer particles.

The weight-average molecular weight of the raw material polyarylene sulfide copolymer and the weight-average molecular weight of the polyarylene sulfide copolymer particles may change depending on the conditions for producing the polyarylene sulfide copolymer particles. The degree of change can be evaluated by the Mw retention, which is the percentage of the weight-average molecular weight of the polyarylene sulfide copolymer particles divided by the molecular weight of the polyarylene sulfide copolymer used to produce the particles. An Mw retention of 50% or more is preferred, more preferably 60% or more, and even more preferably 80% or more. Keeping the Mw retention within the above range is preferable because it allows the mechanical properties of the polyarylene sulfide copolymer particles to be maintained at a high level. The upper limit of the Mw retention is preferably 150% or less, more preferably 130% or less. If the Mw retention exceeds 150%, the viscosity increases and handling becomes difficult. As described below, the Mw retention rate varies depending on the stability of the polyarylene sulfide copolymer when it is dissolved in a solvent in the dissolution step, and can therefore be adjusted by the type of solvent used and the amount of water.

[Polyalkylene glycol]
A particularly preferred water-soluble thermoplastic resin used in the method for producing polyarylene sulfide copolymer particles of the present invention is polyalkylene glycol. There are no particular limitations on the polyalkylene glycol used in the present invention, but specific examples include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polypentamethylene glycol, polyhexamethylene glycol, polyethylene glycol-polytetramethylene glycol copolymers, and alkylphenyl ethers in which the hydroxyl groups at one or both ends of these are blocked with methyl, ethyl, propyl, isopropyl, butyl, hexyl, octyl, decyl, dodecyl, hexadecyl, octadecyl, or the like. Among these, polyethylene glycol or polypropylene glycol is preferred because of its ease of removal by washing, and polyethylene glycol is more preferred.

The lower limit of the weight-average molecular weight of the polyalkylene glycol is preferably 1,000 or more, more preferably 2,000 or more, and even more preferably 10,000 or more. This range is preferable because it allows for a uniform dispersion when the polyalkylene glycol is melt-kneaded with the polyphenylene sulfide copolymer. The upper limit of the weight-average molecular weight of the polyalkylene glycol is preferably 1,000,000 or less, more preferably 800,000 or less, and even more preferably 500,000 or less. The above range is preferable because it allows for ease of removal by washing.

The lower limit of the viscosity ratio ηa/ηb, where ηa is the melt viscosity of the polyarylene sulfide copolymer and ηb is the melt viscosity of the water-soluble thermoplastic resin, is preferably 0.1 or more, and more preferably 1 or more. The upper limit is preferably 1,000 or less, more preferably 500 or less, and even more preferably 300 or less. The closer the melt viscosity ratio ηa/ηb is to 1, the smaller the particle size of the resulting particles tends to be; however, a ratio approaching 1 is not a problem when producing particles with a D50 particle size of 1 μm or more. Furthermore, having the melt viscosity ratio ηa/ηb be equal to or greater than the above lower limit and equal to or less than the above upper limit is preferred, as this allows the production of polyarylene sulfide copolymer particles with a D50 particle size of 1,000 μm or less.

The melt viscosity of the polyarylene sulfide copolymer and water-soluble thermoplastic resin referred to here is the complex viscosity at 300°C obtained by dynamic viscoelasticity measurement in the molten state.

There are no restrictions on the ratio of polyarylene sulfide copolymer to water-soluble thermoplastic resin as long as the polyarylene sulfide copolymer is well dispersed in the water-soluble thermoplastic resin, but the lower limit of the ratio is preferably 1 part by weight or more of polyarylene sulfide copolymer per 100 parts by weight of water-soluble thermoplastic resin, more preferably 10 parts by weight or more, and even more preferably 30 parts by weight or more. The above range is preferable from the standpoint of economy and productivity. Furthermore, from the standpoint of ensuring good dispersion of the polyarylene sulfide copolymer in the polyalkylene glycol during melt-kneading, the polyarylene sulfide copolymer is preferably 100 parts by weight or less of polyarylene sulfide copolymer per 100 parts by weight of polyalkylene glycol, more preferably 80 parts by weight or less, and even more preferably 50 parts by weight or less.

It is also possible to blend components other than the polyarylene sulfide copolymer and water-soluble thermoplastic resin during melt-kneading, and other thermoplastic resins, antioxidants, compatibilizers, etc. may be included. Specific examples of other thermoplastic resins include vinyl chloride resin, vinylidene chloride resin, vinyl acetate resin, polyvinyl alcohol, polyvinyl acetal, polystyrene, AS resin, ABS resin, methacrylic resin, polyethylene, polypropylene, polyamide, polyacetal, polycarbonate, polyethylene terephthalate, polybutylene terephthalate, liquid crystal polyester resin, polyphenylene ether, polyphenylene sulfide, polyarylate, polysulfone, polyethersulfone, polyetherimide, polyetheretherketone, fluororesin, and thermoplastic elastomer. The amount of other components is preferably 10 parts by weight or less, and more preferably 5 parts by weight or less, per 100 parts by weight of the water-soluble thermoplastic resin.

In the method for producing polyarylene sulfide copolymer particles of the present invention, it is necessary to disperse the polyarylene sulfide copolymer in the water-soluble thermoplastic resin. To this end, it is preferable to heat a mixture of the polyarylene sulfide copolymer and the water-soluble thermoplastic resin. The required heating temperature varies depending on the molecular weight, structure, concentration, and type of solvent of the polyarylene sulfide copolymer, but is generally preferably 250°C or higher, more preferably 270°C or higher, and even more preferably 300°C or higher. From the viewpoint of suppressing decomposition of the polyarylene sulfide copolymer and the water-soluble thermoplastic resin, the upper limit is preferably 400°C or lower, and more preferably 320°C or lower.

In this production method, heating can of course be carried out using a conventional polymerization reaction apparatus, but it can also be carried out in a mold for producing a molded product, or using an extruder or melt-kneader. There are no particular restrictions on the method as long as it uses equipment equipped with a heating mechanism, and known methods such as batch and continuous methods can be used. From the standpoint of productivity and the dispersibility of the polyarylene sulfide copolymer in the water-soluble thermoplastic resin, a preferred example is a method of melt-kneading using an extruder. It is preferable to carry out melt-kneading under substantially solvent-free conditions. "Substantially solvent-free" means that the solvent in the mixture is 10% by weight or less, and 3% by weight or less is more preferred.

The heating atmosphere is preferably a non-oxidizing atmosphere, and it is also preferable to carry out the heating under reduced pressure conditions. Furthermore, when carrying out the heating under reduced pressure conditions, it is preferable to first change the atmosphere in the reaction system to a non-oxidizing atmosphere and then to a reduced pressure condition. A non-oxidizing atmosphere refers to an atmosphere in which the oxygen concentration in the gas phase is 5% by volume or less, preferably 2% by volume or less, and more preferably an atmosphere containing substantially no oxygen, i.e., an inert gas atmosphere such as nitrogen, helium, or argon. Among these, a nitrogen atmosphere is particularly preferable from the standpoints of economy and ease of handling. Furthermore, reduced pressure conditions refer to a system in which the reaction is carried out at a pressure lower than atmospheric pressure, with the upper limit of the pressure being preferably 50 kPa or less, more preferably 20 kPa or less, and even more preferably 10 kPa or less. Setting the upper limit of the pressure in this range tends to suppress undesirable side reactions such as crosslinking reactions. An example of a lower limit of the pressure is 0.1 kPa or more. Setting the lower limit of the pressure to 0.1 kPa or more can avoid the burden on the reaction apparatus caused by reducing the pressure more than necessary.

[Step 2]
The production method of the present invention includes a step of melt-kneading a polyarylene sulfide copolymer and a water-soluble thermoplastic resin in step 1, washing the resulting mixture with a solvent in which the water-soluble thermoplastic resin is soluble, and removing the water-soluble thermoplastic resin. Then, the remaining polyarylene sulfide copolymer particles are recovered.

The polyarylene sulfide copolymer can be washed using known methods. Re-slurry washing can be used as a washing method to remove deposits and inclusions from the polyarylene sulfide copolymer particles, and heating may be used as appropriate.

There are no restrictions on the solvent used for washing, as long as it does not dissolve the polyarylene sulfide copolymer particles but dissolves the water-soluble thermoplastic resin. However, alcohols such as methanol, ethanol, and isopropanol, and water are preferred, with water being the most preferred. Washing with water is particularly preferred because it minimizes worker exposure to organic solvents during the granulation process and prevents environmental pollution due to the release of organic solvents into the environment. Washing with water is also preferred because it prevents organic solvents that act as plasticizers from remaining in the polyarylene sulfide copolymer particles, preventing a decrease in mechanical properties when the particles are used as a raw material for three-dimensional objects or reinforced fiber composite substrates.

After the washing step, the polyarylene sulfide copolymer particles are isolated and dried. Isolation methods include, for example, filtration, centrifugation, centrifugal filtration, heat drying, spray drying, and decantation. Drying is preferably carried out below the melting point of the polyarylene sulfide copolymer particles, and may be carried out under reduced pressure. Drying methods that can be selected include air drying, hot air drying, heat drying, reduced-pressure drying, and freeze drying.

[Resin composition containing polyarylene sulfide copolymer particles]
The polyarylene sulfide copolymer particles can also be blended with other optional components, such as a crystal nucleating agent, various fillers, and additives, and used as a resin composition.When blending the polyarylene sulfide copolymer particles of the present invention with components selected from fillers and other additives, a more homogeneous resin composition can be obtained more efficiently than when using conventional polyarylene sulfide copolymer particles.In particular, when blended with a fibrous inorganic filler, the polyarylene sulfide copolymer particles can be blended more homogeneously.By molding a resin composition containing such polyarylene sulfide copolymer particles of the present invention, a molded product with excellent mechanical properties can be obtained.

Examples of nucleating agents include talc, kaolin, organic phosphorus compounds, and polyether ether ketone. Examples of fillers include inorganic fillers and organic fillers. There are no limitations on the type of filler, but considering the reinforcing effect of the filler in the resin composition, fibrous inorganic fillers such as glass fiber and carbon fiber are preferred. Carbon fiber not only improves mechanical properties but also reduces the weight of molded products. Furthermore, carbon fiber is preferred as the filler, as it has a greater effect in improving the mechanical properties and chemical resistance of the resin composition. Additives that can be used include antioxidants, mold release agents, lubricants, UV absorbers, colorants, and foaming agents.

[Uses of polyarylene sulfide copolymer particles]
The polyarylene sulfide copolymer particles of the present invention, which have high heat resistance, high sphericity, and a specific median diameter D50, can be used in injection molding, injection compression molding, blow molding, extrusion molding, and the like, just like polyarylene sulfide copolymers. In addition, they can be used as heat-resistant additives in the fields of adhesive materials, coatings, and polymer compounds, and as raw materials for three-dimensionally molded objects produced by powder bed fusion. The three-dimensionally molded objects have excellent chemical resistance, high heat resistance, and excellent mechanical properties, which are derived from the properties of the polyarylene sulfide copolymer. Furthermore, due to the high fluidity of the polyarylene sulfide copolymer particles of the present invention, which have high sphericity, three-dimensionally molded objects molded from the polyarylene sulfide copolymer particles have uniform and sufficient molded object density and excellent surface quality.

A reinforced fiber composite substrate can also be obtained by dispersing polyarylene sulfide copolymer particles in reinforcing fibers and melting the polyarylene sulfide copolymer particles to impregnate the reinforcing fibers. This method involves dispersing the polyarylene sulfide copolymer particles in the interstices of the reinforcing fibers, melting the polyarylene sulfide copolymer particles, and applying pressure to impregnate the reinforcing fibers with the polyarylene sulfide copolymer. The reinforcing fibers may be continuous or discontinuous. The use of polyarylene sulfide copolymer particles enables the polyarylene sulfide copolymer to be dispersed more efficiently and uniformly in the interstices of the reinforcing fibers. During dispersion, the polyarylene sulfide copolymer particles can be dispersed directly in the reinforcing fibers, or they can be dispersed using a dispersion liquid, as described below. The highly heat-resistant, highly spherical polyarylene sulfide copolymer particles of the present invention exhibit uniform mechanical properties due to their excellent particle dispersibility. Such a reinforced fiber composite substrate is suitable for producing molded articles with high heat resistance.

The polyarylene sulfide copolymer particles of the present invention can also be used as a dispersion in which the polyarylene sulfide copolymer particles are dispersed in a liquid medium. Such a dispersion can be suitably used when producing a reinforced fiber composite substrate using the polyarylene sulfide copolymer particles. After the dispersion is dispersed in reinforcing fibers and the medium is removed by evaporation, the polyarylene sulfide copolymer particles can be melted and impregnated into the reinforcing fibers.

The liquid used as the medium for the dispersion is preferably water or an organic solvent. Specific examples of organic solvents include alcohol compounds such as methanol, ethanol, 1-propanol, and 2-propanol; N-alkylpyrrolidones such as N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, and N-cyclohexyl-2-pyrrolidone; caprolactams such as N-methyl-ε-caprolactam; aprotic organic solvents such as 1,3-dimethyl-2-imidazolidinone, N,N-dimethylacetamide, N,N-dimethylformamide, and hexamethylphosphoric triamide; and organic solvents such as benzene, toluene, o-xylene, m-xylene, and p-xylene. Examples of suitable dispersion media include aromatic hydrocarbons; ketones such as 2-butanone, 3-pentanone, and 4-methyl-2-pentanone; saturated aliphatic hydrocarbons such as cyclopentane, pentane, isopentane, neopentane, methylcyclopentane, cyclohexane, n-hexane, 2-methylpentane, 3-methylpentane, 2,2-dimethylbutane, 2,3-dimethylbutane, methylcyclohexane, heptane, 2-methylhexane, 3-methylhexane, 2,3-dimethylpentane, 2,4-dimethylpentane, and ethylcyclohexane; and mixtures thereof. Water is the most preferred liquid medium. Dispersions can be stabilized using dispersants, typically through entropic, ionic, or steric repulsion.

Three-dimensional objects molded from the polyarylene sulfide copolymer particles of the present invention, molded articles molded from resin compositions containing the polyarylene sulfide copolymer particles of the present invention, and molded articles molded from the reinforced fiber composite substrate of the present invention have excellent heat resistance, chemical resistance, flame retardancy, electrical properties, and mechanical properties, and examples of their applications include electrical and electronic parts, audio equipment parts, household and office electrical appliance parts, machine-related parts, optical equipment, precision machinery-related parts, plumbing parts, automobile and vehicle-related parts, aircraft structural members, aircraft interior materials, and other aerospace-related parts, as well as a variety of other applications.

The method of the present invention will be explained in more detail below using examples and comparative examples, but the present invention is not limited to these examples.

[Analysis of Functional Group Content]
The amount of amino groups in the polyarylene sulfide (A) was calculated based on the absorption intensity at 3382 cm −1 derived from the amino groups relative to the absorption intensity at 1901 cm ⁻¹ derived from the benzene rings of the arylene sulfide units, by measuring an amorphous film prepared by rapidly cooling the polyarylene sulfide from a molten state obtained by heating at 320° ^C using FT-IR (IR-810 infrared spectrophotometer manufactured by JASCO Corporation).

[Molecular weight measurement]
The weight average molecular weight Mw and the number average molecular weight Mn were measured using gel permeation chromatography (GPC), a type of size exclusion chromatography (SEC), and calculated in terms of polystyrene. The GPC measurement conditions are shown below.
Equipment: Senshu Scientific SSC-7110
Column name: Shodex UT806M x 2
Eluent: 1-chloronaphthalene Detector: differential refractive index detector Column temperature: 210°C
Pre-thermostat temperature: 250°C
Pump thermostatic bath temperature: 50°C
Detector temperature: 210°C
Flow rate: 1.0mL/min
Sample injection volume: 300 μL.

[Measurement of Melt Complex Viscosity]
The melt complex viscosity of the polyarylene sulfide copolymer before and after heat treatment was measured, and the loss modulus and storage modulus for calculating the loss tangent were measured using a rheometer under the following conditions.
Device: Anton Paar Physica MCR501
Plate: Parallel (φ25mm)
Gap: 1.0 mm
Angular frequency (ω): 6.28 rad/sec. Sample weight: approximately 0.7 g
Atmosphere: nitrogen gas flow at normal pressure Measurement temperature: 300°C

[Measurement of glass transition temperature, melting point and crystallization temperature]
The glass transition point (Tg), melting point (Tm), and crystallization temperature (Tmc) were measured by differential scanning calorimetry (DSC) using approximately 10 mg of an amorphous film prepared by quenching polyarylene sulfide copolymer particles or polyarylene sulfide copolymer pellets from a molten state. The inflection point of the baseline shift detected when the temperature was increased from 0°C to 340°C at a rate of 20°C/min was taken as the glass transition point. The crystallization temperature was determined as the crystallization peak temperature detected when the temperature was increased from 0°C to 340°C at a rate of 20°C/min, held at 340°C for 1 minute, and then cooled to 100°C at a rate of 20°C/min. The melting point was determined as the melting peak temperature detected when the sample was heated from 0°C to 340°C at a rate of 20°C/min, held at 340°C for 1 minute, cooled to 100°C at a rate of 20°C/min, held at 100°C for 1 minute, and then heated again to 340°C at a rate of 20°C/min.
Device: TA Instruments TA-Q200
Carrier gas: nitrogen Sample purge flow rate: 50 mL/min.

[Particle size and particle size distribution in aqueous dispersion]
A dispersion was prepared by adding approximately 100 mg of polyarylene sulfide copolymer particles or polyarylene sulfide particles to approximately 5 mL of deionized water, and then adding Triton X-100 dropwise until the particles were dispersible. The dispersion was added to a laser diffraction particle size distribution analyzer (Microtrac MT3300EX II) manufactured by Nikkiso Co., Ltd. until it reached a measurable concentration, and ultrasonic dispersion was performed in the analyzer at 30 W for 60 seconds, after which the particle size distribution was measured over a measurement time of 10 seconds.

[Sphericity]
The sphericity of the polyarylene sulfide copolymer particles or polyarylene sulfide particles was calculated from the major and minor axes of 30 randomly selected particles observed in a photograph taken with a Keyence digital microscope (VHX-7000) according to the following formula: The major axis is the diameter at which the distance between two parallel lines is greatest when an image of the particle is sandwiched between two parallel lines, and the minor axis is the diameter at which the distance between two parallel lines is smallest when an image of the particle is sandwiched between two parallel lines in a direction perpendicular to the major axis.

In the formula, S is the sphericity, n is the number of measurements, a _i is the major axis of the i-th particle, and b _i is the minor axis of the i-th particle. The number of measurements, n, is set to 30.

[Reference example 1]
An autoclave equipped with a stirrer and a bottom plug valve was charged with 9.5 kg (81.9 mol) of 48.4% sodium hydrosulfide, 3.84 kg (93.1 mol) of 97% sodium hydroxide, 13.4 kg (135 mol) of N-methyl-2-pyrrolidone (NMP), and 9.82 kg of ion-exchanged water, and gradually heated to 225°C over approximately 3 hours at atmospheric pressure while passing nitrogen through. When the temperature reached 225°C, heating was stopped and cooling was initiated.

The reaction vessel was then cooled to 200°C, and 12.6 kg (85.9 mol) of p-dichlorobenzene (p-DCB), 1.07 kg (8.23 mol) of 4-aminothiophenol (4-ATP), and 19.8 kg (200 mol) of NMP were added. The reaction vessel was then sealed under nitrogen gas and heated to 260°C at a rate of 0.6°C/min with stirring, and the reaction was carried out at 260°C for 120 minutes.

After the reaction was completed, the autoclave's bottom plug valve was immediately opened, and the contents were flushed into a stirrer-equipped device. The contents were then dried and solidified for 1.5 hours at 230°C in the stirrer-equipped device, and a solid material containing PPS and salts was recovered.

The resulting solid and ion-exchanged water were placed in an autoclave equipped with a stirrer, and a washing process was carried out at 75°C for 15 minutes, after which the solid was filtered through a filter. This process was repeated three times to obtain a cake. The resulting cake and 30 liters of ion-exchanged water were placed in an autoclave equipped with a stirrer, and the atmosphere inside the autoclave was replaced with nitrogen, after which the temperature was raised to 195°C. The autoclave was then cooled, and the contents were filtered through a filter to obtain a cake. The resulting cake was dried at 120°C under a nitrogen stream.

3 kg of the dried cake and 30 kg of N-methyl-2-pyrrolidone (NMP) were placed in a container equipped with a stirrer and stirred for 30 minutes, then filtered to obtain a cake. The resulting cake was washed with 30 liters of ion-exchanged water for 15 minutes and filtered three times, and then dried at 120°C for 4 hours under a nitrogen stream to obtain dried PPS. The amino group content of the resulting PPS was 510 μmol/g and the number average molecular weight was 3,200.

[Reference example 2]
The PPS obtained in Reference Example 1 and pyromellitic anhydride were dry-blended so that the molar ratio of the amount of acid anhydride groups in pyromellitic anhydride to the amount of amino groups in PPS was 1.200, and the mixture was melt-kneaded using a TEX30α type twin-screw extruder (L/D: 45, kneading zones: 3) manufactured by The Japan Steel Works, Ltd., equipped with a vacuum vent, at a cylinder temperature of 300°C and a screw rotation speed of 200 rpm to cause reaction, thereby obtaining a PPS copolymer.

The FT-IR spectrum confirmed that the resulting PPS copolymer contained phenylene sulfide units as structural units and that imide groups had been introduced. DSC measurements revealed that the PPS copolymer had a glass transition temperature of 114°C, a crystallization temperature of 171°C, and a melting point of 263°C. GPC measurements revealed that the Mw was 46,700. The melt complex viscosity was 240 Pa·s. The PPS copolymer was in pellet form. The results are summarized in Table 1.

[Reference example 3]
A PPS copolymer was obtained in the same manner as in Reference Example 2, except that the pyromellitic anhydride and PPS were dry-blended so that the molar ratio of the amount of acid anhydride contained in the pyromellitic anhydride to the amount of amino groups contained in the PPS was 1.213.

The FT-IR spectrum confirmed that the resulting PPS copolymer contained phenylene sulfide units as structural units and that imide groups had been introduced. DSC measurements revealed that the PPS copolymer had a glass transition temperature of 114°C, a crystallization temperature of 205°C, and a melting point of 262°C. GPC measurements revealed that the Mw was 48,600. The melt complex viscosity was 176 Pa·s. The PPS copolymer was in pellet form. The results are summarized in Table 1.

[Example 1]
4.0 g of the PPS copolymer obtained in Reference Example 2 and 6.0 g of PEG20000 (manufactured by Tokyo Chemical Industry Co., Ltd.) (melt complex viscosity: 0.80 Pa s) were added to a small melt kneader equipped with a circulation mechanism, Haake MiniLab II, and melt-kneaded for 3 minutes at a cylinder temperature of 300 ° C and a screw rotation speed of 200 rpm, and then discharged into a tray filled with ion-exchanged water. At this time, the melt complex viscosity ratio (ηa/ηb) of the melt viscosity of the PPS copolymer (ηa) to the melt viscosity of the PEG20000 (ηb) was 301. Suction filtration was performed using filter paper as a filter medium, and the resulting cake was reslurried with ion-exchanged water and suction-filtered using filter paper. This washing process was repeated three times to obtain polyarylene sulfide copolymer particles. The glass transition temperature of the polyarylene sulfide copolymer particles was 110 ° C, and the melting point was 259 ° C. The Mw was 53,000, and the Mw retention of the PPS copolymer particles relative to the Mw of the PPS copolymer of Reference Example 2 was 113%. The polyarylene sulfide copolymer particles had a D50 of 80.6 μm and a D90/D10 of 1.7. The sphericity was 93. The results are summarized in Table 1.

[Example 2]
PPS copolymer particles were obtained in the same manner as in Example 1, except that PEG500000 (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) (melt complex viscosity: 7.9 Pa s) was used instead of PEG20000. The melt complex viscosity ratio (ηa/ηb) of the melt viscosity (ηa) of the PPS copolymer to the melt viscosity (ηb) of PEG500000 was 30. The polyarylene sulfide copolymer particles had a glass transition temperature of 110°C and a melting point of 261°C. The Mw was 51,800, and the Mw retention of the PPS copolymer particles relative to the Mw of the PPS copolymer of Reference Example 2 was 111%. The polyarylene sulfide copolymer particles had a D50 of 5.9 μm and a D90/D10 of 2.1. The sphericity was 93. The results are summarized in Table 1.

[Example 3]
PPS copolymer particles were obtained in the same manner as in Example 2, except that the PPS copolymer of Reference Example 3 was used instead of the PPS copolymer of Reference Example 2. At this time, the melt complex viscosity ratio (ηa/ηb) of the melt viscosity (ηa) of the PPS copolymer to the melt viscosity (ηb) of PEG 500000 was 22. The polyarylene sulfide copolymer particles had a glass transition point of 110°C and a melting point of 261°C. The Mw was 46,200, and the Mw retention of the PPS copolymer particles relative to the Mw of the PPS copolymer of Reference Example 3 was 95%. The polyarylene sulfide copolymer particles had a D50 of 4.4 μm and a D90/D10 of 2.0. The sphericity was 89. The results are summarized in Table 1.

[Comparative Example 1]
1.5 g of the PPS copolymer obtained in Reference Example 2 was freeze-pulverized in liquid nitrogen for 23 minutes. The polyarylene sulfide copolymer particles had a D50 of 198 μm and a D90/D10 ratio of 12.7. The sphericity was 64%. The results are summarized in Table 2.

[Comparative Example 2]
A 20 mL pressure vessel was charged with 0.3 g of the PPS copolymer obtained in Reference Example 2 and 4.5 g of NMP containing 1000 ppm water. The vessel was then purged with nitrogen and sealed. After heating at 250°C for 20 minutes while stirring at 240 rpm, the vessel was allowed to cool. After cooling to approximately room temperature over approximately 30 minutes while maintaining stirring, the mixture was removed from the pressure vessel, 20 mL of water was added, and the mixture was stirred and filtered. After repeated stirring and filtration in water to remove the solvent, the mixture was vacuum dried at 100°C to obtain polyarylene sulfide copolymer particles. The polyarylene sulfide copolymer particles had a glass transition temperature of 110°C, a crystallization temperature of 214°C, and a melting point of 261°C. The Mw was 25,300, and the Mw retention of the PPS copolymer particles relative to the Mw of the PPS copolymer of Reference Example 2 was 37%. The polyarylene sulfide copolymer particles in the methanol dispersion had a D50 of 15.9 μm, a D90/D10 ratio of 5.5, and a sphericity of 76%. The results are summarized in Table 2.

[Reference example 4]
A 70-liter autoclave equipped with a stirrer was charged with 8.27 kg (70.00 mol) of 47.5% sodium hydrosulfide, 2.96 kg (70.97 mol) of 96% sodium hydroxide, 11.43 kg (115.50 mol) of N-methyl-2-pyrrolidone (NMP), 2.58 kg (31.50 mol) of sodium acetate, and 10.5 kg of ion-exchanged water, and gradually heated to 245°C over approximately 3 hours at atmospheric pressure while passing nitrogen through. After distilling off 14.78 kg of water and 0.28 kg of NMP, the reaction vessel was cooled to 160°C.

Next, 10.24 kg (69.63 mol) of p-dichlorobenzene and 9.01 kg (91.00 mol) of NMP were added, and the reaction vessel was sealed under nitrogen gas. The temperature was raised to 238°C at a rate of 0.6°C/min while stirring. After 95 minutes of reaction at 238°C, the temperature was raised to 270°C at a rate of 0.8°C/min. After 100 minutes of reaction at 270°C, the mixture was cooled to 250°C at a rate of 1.3°C/min while 1.26 kg (70 mol) of water was injected over 15 minutes. The mixture was then cooled to 200°C at a rate of 1.0°C/min, and then rapidly cooled to near room temperature.

The contents were removed from the reaction vessel and diluted with 26.30 kg of NMP. The solvent and solids were filtered through an 80-mesh sieve, and the resulting particles were washed with 31.90 kg of NMP and then filtered. These were washed several times with 56.00 kg of ion-exchanged water and filtered, and then washed with 70.00 kg of a 0.05 wt. % aqueous acetic acid solution and filtered. After further washing with 70.00 kg of ion-exchanged water and filtering, the resulting hydrated PPS particles were dried with hot air at 80°C and then dried under reduced pressure at 120°C. The PPS particles had a glass transition temperature of 94°C, a crystallization temperature of 219°C, and a melting point of 278°C. The Mw was 75,100. The results are summarized in Table 2.

[Comparative Example 3]
PPS particles were obtained under the same conditions as in Comparative Example 2, except that the PPS obtained in Reference Example 4 was used instead of the PPS copolymer obtained in Reference Example 2. The PPS particles had a glass transition temperature of 94°C, a crystallization temperature of 220°C, and a melting point of 278°C. The Mw was 73,300, and the Mw retention of the PPS particles relative to the Mw of the PPS in Reference Example 3 was 98%. The PPS particles had a D50 of 57.4 μm and a D90/D10 of 2.6. The sphericity was 73%. The results are summarized in Table 2.

[Reference example 5]
Melt kneading was carried out in the same manner as in Example 1, except that polyvinylpyrrolidone (K-30) (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was used instead of PEG20000. However, the resulting mixture did not dissolve in ion-exchanged water, and no particles were obtained. At this time, the melt complex viscosity ratio (ηa/ηb) was 0.06. The results are summarized in Table 2.

[Reference example 6]
Melt kneading was carried out in the same manner as in Example 1, except that polyvinyl alcohol Mowiflex C-17 (manufactured by Kuraray Co., Ltd.) was used instead of PEG20000. However, the process was interrupted due to the generation of a large amount of decomposition gas, and no particles were obtained. At this time, the melt complex viscosity ratio (ηa/ηb) was 0.006. The results are summarized in Table 2.

[Comparative Example 4]
PPS particles were obtained under the same conditions as in Example 1, except that the PPS obtained in Reference Example 4 was used instead of the PPS copolymer obtained in Reference Example 2. The melt complex viscosity ratio (ηa/ηb) of the melt viscosity of PPS (ηa) to the melt viscosity of PEG 20000 (ηb) was 297. The PPS particles had a glass transition temperature of 94°C, a crystallization temperature of 220°C, and a melting point of 278°C. The Mw was 66,000, and the Mw retention of the PPS particles relative to the Mw of the PPS of Reference Example 4 was 88%. The PPS particles had a D50 of 303 μm and a D90/D10 of 6.4. The sphericity was 86%. The results are summarized in Table 2.

Examples 1 to 3 demonstrate that the method of the present invention can produce polyarylene sulfide copolymer particles with high heat resistance and high sphericity.

As shown in Comparative Example 1, when pellet-shaped PPS copolymer was freeze-pulverized, the sphericity was lower than that of the PPS copolymer particles obtained in Examples 1 to 3. Furthermore, both the D50 particle size and D90/D10 were larger.

Comparative Examples 2 and 3 showed that the particles obtained by dissolving and precipitating PPS copolymer or PPS in a solvent had low sphericity, and in the case of PPS, the Tg was low and the heat resistance was poor.

Claims (12)

Polyarylene sulfide copolymer particles having a median diameter D50 of 1 μm or more and 1,000 μm or less, a glass transition point of 95°C or more and 190°C or less when measured using a differential scanning calorimeter, and a sphericity of 80 or more and 100 or less. Polyarylene sulfide copolymer particles according to claim 1, having a median diameter D50 of 1 μm or more and 150 μm or less. Polyarylene sulfide copolymer particles according to claim 1, having a weight average molecular weight Mw of 30,000 or more. The polyarylene sulfide copolymer particles according to claim 1, wherein the polyarylene sulfide copolymer constituting the polyarylene sulfide copolymer particles contains at least one bonding group selected from a sulfonyl group, a sulfinyl group, an ester group, an amide group, an imide group, an ether group, a urea group, a urethane group, and a siloxane group. A method for producing polyarylene sulfide copolymer particles, comprising step 1 of melt-kneading a polyarylene sulfide copolymer having a glass transition temperature of 95°C or higher and 190°C or lower as measured using a differential scanning calorimeter with a water-soluble thermoplastic resin, and step 2 of removing the water-soluble thermoplastic resin by washing with water or an alcohol. The method for producing polyarylene sulfide copolymer particles according to claim 5, wherein the viscosity ratio ηa/ηb between the melt viscosity (ηa) of the polyarylene sulfide copolymer and the melt viscosity (ηb) of the water-soluble thermoplastic resin is 0.1 or more and 1000 or less. A dispersion in which the polyarylene sulfide copolymer particles described in claim 1 are dispersed in a liquid. A three-dimensional object molded from the polyarylene sulfide copolymer particles described in claim 1. A method for producing a reinforced fiber composite substrate, comprising the steps of dispersing the polyarylene sulfide copolymer particles according to claim 1 in reinforcing fibers, and melting the polyarylene sulfide copolymer particles to impregnate the reinforcing fibers. A reinforcing fiber composite substrate produced by the method for producing a reinforcing fiber composite substrate described in claim 9. A molded article formed from the reinforcing fiber composite substrate described in claim 10. The molded article according to claim 11, which is an aircraft structural component.