Method for producing polyarylene sulfide

Abstract

To provide a method for efficiently producing a polyarylene sulfide having a high molecular weight of an amino group, and a high molecular weight.SOLUTION: In a method for producing a polyarylene sulfide, in which an inorganic sulfidation agent, a dihalogenated aromatic compound, and a compound (A) having a specific structure are reacted in an organic polar solvent in the presence of an alkali metal hydroxide, there is provided a method, wherein 0.008 mol or more of the compound (A) is present per mole of the inorganic sulfidation agent in a reaction vessel to produce the polyarylene sulfide by way of following steps. Step 1 : a step of forming a prepolymer by reacting, the inorganic sulfidation agent, dihalogenated aromatic compound, and the compound A, in an organic polar solvent in the presence of the alkali metal hydroxide, with a temperature of 200°C or higher and 240°C or lower, and a polymerization time including temperature rise and fall time of 1 hour or more and 4 hours or less. Step 2 : a step of obtaining polyarylene sulfide from the prepolymer at a temperature of 265°C or higher and less than 280°C.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing a polyarylene sulfide having an amino group. [Background technology]

[0002] Polyarylene sulfides (hereinafter sometimes abbreviated as PAS), typified by polyphenylene sulfide (hereinafter abbreviated as PPS), have properties suitable for engineering plastics, such as excellent heat resistance, gas 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, etc., primarily for injection molding and extrusion molding. Due to its excellent properties, the applications of PAS have been expanding in recent years.

[0003] However, PAS has few reactive functional groups in its molecular chain, making it less interactive and reactive than other engineering plastics such as polyamides and polyesters, making it difficult to bond or composite with different materials. Furthermore, problems have been pointed out, such as the further deterioration of the strength and toughness of composite materials after long-term hot water treatment or long-term dry heat treatment. In particular, with the recent market demand for improved fuel economy, weight reduction, and cost reduction in automobiles, there is a demand for superior materials that can achieve high strength through improved adhesion with different materials and that do not experience a decrease in strength or toughness even after long-term hot water treatment or long-term dry heat treatment.

[0004] Therefore, studies have been reported on introducing reactive functional groups into PAS with the aim of improving adhesion to different materials. For example, Patent Document 1 discloses a method for producing PAS having carboxyl groups by copolymerizing 2,4-dichlorobenzoic acid. Patent Document 2 discloses a method for producing PAS having specific functional groups by heating cyclic arylene sulfide with a sulfur-containing compound having an amino group or a carboxyl group. Patent Document 3 discloses a method for introducing carboxyl groups to the terminals of PAS by reacting a monohalogenated compound containing a specific functional group with an alkali metal hydroxide during PAS production. Patent Document 4 discloses a method for producing PAS having amino groups using a thiol compound having an amino group. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 4-283247 [Patent Document 2] International Publication No. 2012 / 057319 [Patent Document 3] Japanese Patent Application Laid-Open No. 2017-066261 [Patent Document 4] Japanese Patent Publication No. 2020-084027 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the manufacturing method disclosed in Patent Document 1 has the problem that, although reactive functional groups can be introduced, the molecular weight is low and the strength and toughness of the molded product are low. The manufacturing method disclosed in Patent Document 2 has the problem that it is difficult to achieve both a high functional group content and a high molecular weight, and it requires many steps and is not simple. The manufacturing method disclosed in Patent Document 3 can be expected to achieve a relatively high reactive functional group content, but has the problem that the molecular weight is extremely low and the strength when processed into a product is low. Furthermore, the manufacturing method disclosed in Patent Document 4 can be expected to achieve a relatively high molecular weight, but has the problem that the reactive functional group content is low and the strength decreases when subjected to long-term hot water treatment.

[0007] As described above, it is difficult for the PASs described in Patent Documents 1 to 4 to achieve both a high reactive functional group content and a high molecular weight, and there is a problem in that the resin compositions obtained from such PASs cannot be used for electric / electronic parts, communication device parts, or automobile parts.

[0008] An object of the present invention is to efficiently obtain a PAS having a high amino group content and a high molecular weight. [Means for solving the problem]

[0009] The present invention has been made to solve the above-mentioned problems, and can be realized by providing the following contents. 1. A method for producing polyarylene sulfide by reacting an inorganic sulfidizing agent, a dihalogenated aromatic compound, and compound (A) in an organic polar solvent in the presence of an alkali metal hydroxide, wherein compound (A) is present in a reaction vessel in an amount of 0.008 moles or more per mole of inorganic sulfidizing agent, and compound (A) is a compound having at least one aromatic ring and having, on said aromatic ring, a reactive functional group consisting of an amino 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, the method comprising the following steps 1 and 2, and wherein the weight-average molecular weight of the polyarylene sulfide is 30,000 or more: Step 1: A step of producing a polyarylene sulfide prepolymer by subjecting an inorganic sulfidizing agent, a dihalogenated aromatic compound, and compound (A) to an organic polar solvent in the presence of an alkali metal hydroxide at a temperature of 200°C or higher and 240°C or lower for a polymerization time of 1 hour or higher and 4 hours or lower, including the time for temperature increase and decrease. Step 2: Following step 1, a step of obtaining polyarylene sulfide from the prepolymer within a temperature range of 265°C or higher and lower than 280°C. 2. The method for producing polyarylene sulfide according to 1, wherein in step 2, 1 mole or more and 1.8 moles or less of water are present in the reaction vessel per mole of the inorganic sulfidizing agent. 3. A method for producing polyarylene sulfide according to item 1 or 2, characterized in that 0.01 mole or more and 1 mole or less of an alkali metal carboxylate is present per mole of an inorganic sulfidizing agent. [Effects of the Invention]

[0010] According to the present invention, a PAS having a high amino group content and a high molecular weight can be efficiently obtained. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present invention will be described in detail.

[0012] The PAS of the present invention is a homopolymer or copolymer whose main constituent unit is a repeating unit of the formula -(Ar-S)-, preferably containing 80 mol % or more of this repeating unit. Ar includes units represented by the following formulas (A) to (K), with formula (A) being particularly preferred.

[0013] [ka]

[0014] (R1 and R2 are substituents selected from hydrogen, alkyl groups, alkoxy groups, and halogen groups, and R1 and R2 may be the same or different.)

[0015] As long as this repeating unit is the main structural unit, it may contain a small amount of branching units or crosslinking units represented by the following formulas (L) to (N), etc. The copolymerization amount of these branching units or crosslinking units is preferably in the range of 0 to 1 mol % per 1 mol of -(Ar-S)- units.

[0016] [ka]

[0017] Furthermore, the PAS in the present invention may be any of a random copolymer, a block copolymer, and a mixture thereof containing the above repeating unit.

[0018] Representative examples of these include polyphenylene sulfide, polyphenylene sulfide sulfone, polyphenylene sulfide ketone, their random copolymers, block copolymers, and mixtures thereof. Particularly preferred PASs contain the following p-phenylene sulfide unit as the main structural unit of the polymer:

[0019] [ka]

[0020] and polyphenylene sulfide resins containing 80 mol % or more, particularly 90 mol % or more of the above.

[0021] The method for producing a PAS of the present invention will be specifically described below.

[0022] First, we will explain the raw materials used in the production of PAS.

[0023] [Inorganic sulfidizing agent] The inorganic sulfidizing agent used in the PAS production method of the present invention 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.

[0024] 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, aqueous mixtures, or anhydrous forms. 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.

[0025] 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, and sodium hydrosulfide is more preferably used.

[0026] Alternatively, an alkali metal sulfide prepared in a reaction system from an alkali metal hydrosulfide and an alkali metal hydroxide can be used. Alternatively, an alkali metal sulfide prepared in advance by contacting an alkali metal hydrosulfide with an alkali metal hydroxide can be used. These alkali metal hydrosulfides and alkali metal hydroxides can be used as hydrates, aqueous mixtures, or anhydrous forms, with hydrates or aqueous mixtures being preferred from the standpoints of availability and cost.

[0027] Furthermore, 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.Alkali metal sulfides prepared in advance by contacting an alkali metal hydroxide such as lithium hydroxide or sodium hydroxide with hydrogen sulfide can also be used.Hydrogen sulfide may be used in any form, whether gaseous, liquid, or aqueous solution.

[0028] [Dihalogenated aromatic compound] Dihalogenated aromatic compounds used in the PAS manufacturing method of the present invention 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 containing non-halogen substituents 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, and 3,5-dichloroaniline. Among these, dihalogenated aromatic compounds primarily composed of p-dihalogenated benzenes, such as p-dichlorobenzene, are preferred. Particularly preferred are those containing 80 to 100 mol % of p-dichlorobenzene, and even more preferably 90 to 100 mol %. It is also possible to use a combination of two or more different dihalogenated aromatic compounds.

[0029] [Compound (A)] The compound (A) used in the PAS production method of the present invention has at least one aromatic ring and, on the aromatic ring, a reactive functional group consisting of an amino 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. Specific examples of preferred compounds include o-aminophenol, p-aminophenol, m-aminophenol, o-aminothiophenol, p-aminothiophenol, m-aminothiophenol, and compounds in which the hydroxyl or thiol group is a salt of an alkali metal or alkaline earth metal. From the viewpoint of reactivity, p-aminophenol and p-aminothiophenol are particularly preferred. Two or more different compounds (A) may be used in combination as long as they have the above characteristics. When using a compound having a hydroxyl or thiol group as compound (A), it is preferable to simultaneously use an equal amount of an alkali metal hydroxide. When using a compound in which the hydroxyl or thiol group is in the form of a salt as compound (A), the salt can be formed in advance before use in the production of PAS, or the salt can be formed during the reaction in a reaction vessel.

[0030] In the present invention, it is essential that compound (A) be present in the reaction vessel in an amount of 0.008 moles or more per mole of inorganic sulfidizing agent, with 0.009 moles or more being preferred, and 0.010 moles or more being more preferred. By using 0.008 moles or more of compound (A) per mole of inorganic sulfidizing agent, amino groups can be sufficiently introduced into the PAS, and when the resulting resin composition is prepared, a decrease in tensile strength after long-term hot water treatment can be suppressed, which is preferable. Furthermore, from the viewpoint of increasing the molecular weight of the PAS and improving its mechanical properties, compound (A) is preferably present in an amount of 0.05 moles or less per mole of inorganic sulfidizing agent, more preferably 0.04 moles or less, and even more preferably 0.03 moles or less.

[0031] [Organic polar solvents] Preferred examples of organic polar solvents used in the PAS production method of the present invention 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 preferred due to their high reaction stability. Among these, N-methyl-2-pyrrolidone and 1,3-dimethyl-2-imidazolidinone are preferred, with N-methyl-2-pyrrolidone being more preferred.

[0032] [Polymerization aid] One preferred embodiment involves the use of a polymerization aid to obtain a PAS with a relatively high degree of polymerization in a shorter time. Here, polymerization aid refers to a substance that increases the viscosity of the resulting PAS. 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 can be used alone or in combination of two or more. Among these, organic carboxylates, water, and alkali metal chlorides are preferred, with alkali metal carboxylates being preferred as organic carboxylates and lithium chloride being preferred as alkali metal chlorides.

[0033] The alkali metal carboxylate is 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, sodium phenylacetate, potassium p-toluate, and mixtures thereof.

[0034] 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. Among the alkali metal carboxylates, 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.

[0035] The water used in the polymerization aid is preferably distilled water or ion-exchanged water so as not to impair the desired effect of chemical modification of PAS.

[0036] In the present invention, it is preferable to use an alkali metal carboxylate as the polymerization aid, and it is more preferable to use sodium acetate. In this case, it is preferable to have 0.01 moles or more of the polymerization aid present per mole of the inorganic sulfidizing agent. From the viewpoint of achieving a higher molecular weight, it is more preferable to have 0.1 moles or more, and even more preferable to have 0.2 moles or more. Furthermore, from the viewpoint of solubility, it is preferable to have 1 mole or less of the polymerization aid present per mole of the inorganic sulfidizing agent, more preferably 0.8 moles or less, and even more preferably 0.6 moles or less.

[0037] In the present invention, it is preferable to use water as a polymerization aid, and in this case, it is preferable to have 1 mole or more of water present in the reaction vessel per mole of inorganic sulfidizing agent. In terms of obtaining a higher degree of polymerization, 1.3 moles or more is more preferable, and 1.5 moles or more is even more preferable. When water is used as a polymerization aid, the upper limit is preferably 1.8 moles or less of water per mole of inorganic sulfidizing agent in the reaction vessel, from the viewpoint of safety regarding the pressure in the reaction vessel.

[0038] Of course, two or more of these polymerization aids can be used in combination. For example, when an alkali metal carboxylate and water are used in combination, a higher molecular weight can be achieved with smaller amounts of the alkali metal carboxylate and water.

[0039] The timing of addition of these polymerization aids is not particularly specified, and they may be added at any time during the pre-step, at the start of polymerization, or during the polymerization reaction step, as described below, or may be added in multiple batches. When an alkali metal carboxylate is used as the polymerization aid, it is more preferable to add it simultaneously with other additives at the start of the pre-step or at the start of polymerization, from the viewpoint of ease of addition. Furthermore, when water is used as the polymerization aid, it is effective to add it during the polymerization reaction step after charging the dihalogenated aromatic compound.

[0040] [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.

[0041] These polymerization stabilizers can be used alone or in combination of two or more. The polymerization stabilizer is preferably used in a proportion of usually 0.02 mol to 0.2 mol, preferably 0.03 mol to 0.1 mol, more preferably 0.04 mol to 0.09 mol, per mol of the charged inorganic sulfidizing agent. If this proportion is too small, the stabilizing effect is insufficient, and conversely, if it is too large, it is economically disadvantageous and the polymer yield tends to decrease.

[0042] The timing of adding the polymerization stabilizer is not particularly specified, and it may be added at any time during the pre-step, at the start of polymerization, or during the polymerization reaction step described below, or may be added in multiple divided portions, but it is more preferable to add it simultaneously at the start of the pre-step or at the start of polymerization from the viewpoint of ease.

[0043] Next, a preferred method for producing the PAS of the present invention will be specifically explained in order, including the pre-process, polymerization reaction process, recovery process, and post-treatment process, but the present invention is not limited to this method.

[0044] [Pre-process] In the method for producing PAS, the inorganic sulfidizing agent is usually used in the form of a hydrate, and it is preferable to heat the mixture containing the organic polar solvent and the inorganic sulfidizing agent and remove excess water from the system before adding the dihalogenated aromatic compound.

[0045] 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 separate vessel from the polymerization vessel. While there are no particular limitations on this method, a preferred method involves adding alkali metal hydrosulfide and alkali metal hydroxide to an organic polar solvent under an inert gas atmosphere at room temperature to 150°C, preferably room temperature to 100°C, and then heating the mixture to at least 150°C, preferably 180°C to 260°C, under atmospheric or reduced pressure, to distill off water. Compound (A) and a polymerization aid may also be added at this stage. These raw materials may be added in any order, even simultaneously. To promote the distillation of water, toluene or the like may be added during the reaction.

[0046] At the end of the pre-step, i.e., before the polymerization reaction step, the amount of water in the system is preferably 0.01 to 10.0 moles per mole of the charged sulfidizing agent. Here, the amount of water in the system is the amount of water charged into 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.

[0047] [Polymerization reaction process] The present invention essentially includes a step (hereinafter sometimes referred to as step 1) of producing a PAS prepolymer from an inorganic sulfidizing agent, a dihalogenated aromatic compound, and compound (A) in an organic polar solvent in the presence of an alkali metal hydroxide at a temperature ranging from 200°C to 240°C for a polymerization time of from 1 hour to 4 hours, including the time for heating and cooling, and a step (hereinafter sometimes referred to as step 2) of obtaining a PAS from the prepolymer at a temperature ranging from 265°C to less than 280°C, following step 1.

[0048] [Process 1] Step 1 will be explained in more detail. When starting Step 1, an organic polar solvent, an inorganic sulfidizing agent, and a 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 (A) and a polymerization aid may also be added at this stage. These raw materials may be charged in any order, or simultaneously.

[0049] The mixture is heated and step 1 begins.

[0050] In step 1, the temperature program within the temperature range of 200° C. to 240° C. may be any of a temperature increase process, a process of maintaining a constant temperature, and a temperature decrease process, or a combination of two or more of these processes. From the viewpoint of production efficiency and simplicity, a temperature increase process alone or a combination of a temperature increase process and a process of maintaining a constant temperature is preferred.

[0051] For example, when a temperature rising process is employed, the temperature rising rate is preferably selected to be 0.01°C / min to 5°C / min, and more preferably in the range of 0.1°C / min to 3°C / min.

[0052] The polymerization time, including the time for increasing and decreasing the temperature within the temperature range of 200° C. to 240° C., is preferably 1 hour or more, more preferably 2 hours or more, and even more preferably 3 hours or more, from the viewpoint of increasing the conversion rate of the polyhalogenated aromatic compound (abbreviated as PHA herein). Note that a polymerization time, including the time for increasing and decreasing the temperature within the temperature range of 200° C. to 240° C., of more than 4 hours is not preferable from the viewpoint of productivity.

[0053] In order to obtain a polymer with a higher degree of polymerization, it is effective for the conversion rate of PHA in the system at the end of step 1 to reach 40 mol% or more, preferably 60 mol% or more, and more preferably 80 mol% or more. Here, the conversion rate of PHA is a value calculated using the following formula. The amount of residual PHA can usually be determined by gas chromatography. (A) When polyhalogenated aromatic compounds are added in excess of alkali metal sulfides in terms of molar ratio Conversion rate = [PHA charge amount (mol) - PHA remaining amount (mol)] / [PHA charge amount (mol) - PHA excess amount (mol)] (B) Cases other than (A) above Conversion rate = [PHA charge amount (mol) - PHA remaining amount (mol)] / [PHA charge amount (mol)]

[0054] [Process 2] Step 2 will be described in more detail. After step 1, the temperature is finally raised to a temperature range of 265°C or higher and lower than 280°C, and the reaction is carried out at that temperature for a certain period of time. After step 1, there are no particular restrictions on the rate at which the temperature may be raised to a temperature range of 265°C or higher and lower than 280°C, 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.

[0055] The polymerization time within the temperature range of 265°C or higher and lower than 280°C is usually preferably 0.25 hours or longer, and more preferably 0.5 hours or longer, from the viewpoint of reacting and increasing the molecular weight of the prepolymer produced in step 1. There is no particular upper limit to the polymerization time, but from the viewpoint of productivity, it is preferably 20 hours or shorter, more preferably 10 hours or shorter, and even more preferably 5 hours or shorter.

[0056] In step 2, it is preferable to have 1 mole or more of water present in the reaction vessel per mole of inorganic sulfidizing agent. In terms of obtaining a higher degree of polymerization, 1.3 moles or more is more preferable, and 1.5 moles or more is even more preferable. When water is used as a polymerization aid, the upper limit is preferably 1.8 moles or less of water per mole of inorganic sulfidizing agent in the reaction vessel, from the viewpoint of safety regarding the pressure in the reaction vessel. The amount of water in step 2 refers to the amount of water when the polymerization reaction is proceeding in step 2 within a temperature range of 265°C or higher and lower than 280°C.

[0057] To ensure that 1 mole or more and 1.8 moles or less of water is present in the reaction vessel per mole of the inorganic sulfidizing agent, water may be added to the reaction vessel, or the reaction vessel may be partially opened to remove water. A combination of these methods is also possible. From the viewpoints of safety and simplicity, adding water is preferred.

[0058] Adding compound (A) to the reaction vessel at this stage is not preferable because it reduces the molecular weight of the prepolymer produced in step 1. The reason for this is unclear, but it is presumed to be because the reaction rate at which compound (A) cleaves the PAS main chain is higher than the reaction rate at which the PAS increases in molecular weight.

[0059] [Recovery process] In the method for producing PAS, after the polymerization is completed, solid matter is recovered from the polymerization reaction product containing the polymer, solvent, etc. Any known recovery method may be used.

[0060] For example, after the polymerization reaction is completed, the polymer may be slowly cooled and recovered in particulate form. The cooling rate is not particularly limited, but is typically about 0.1°C / min to 3°C / min. It is not necessary to cool at the same rate throughout the entire cooling process; instead, the polymer may be 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.

[0061] Another preferred method is to carry out the above recovery under rapid cooling conditions. Among these recovery methods, a flash method is preferred. In the flash method, the polymerization reaction product is subjected to high temperature and high pressure (usually 250°C or higher, 8 kg / cm 2 This method involves flashing the polymer from the above-mentioned state into an atmosphere under normal pressure or reduced pressure, recovering the solvent and simultaneously recovering the polymer in powder form. The term "flashing" used here means ejecting the polymerization product from a nozzle. The flashing atmosphere can be specifically nitrogen or water vapor under normal pressure, and the temperature is usually selected within the range of 150°C to 250°C.

[0062] [Post-processing process] The PAS may be produced through the above-mentioned polymerization and recovery steps, and then subjected to acid treatment, hot water treatment, washing with an organic solvent, or alkali metal or alkaline earth metal treatment.

[0063] Acid treatment is carried out as follows. There are no particular restrictions on the acid used in the acid treatment of PAS, as long as it does not have the effect of decomposing PAS, and examples include acetic acid, hydrochloric acid, sulfuric acid, phosphoric acid, silicic acid, carbonic acid, and propylic acid. Of these, acetic acid and hydrochloric acid are more preferably used. On the other hand, acids such as nitric acid that decompose and deteriorate PAS are not preferred.

[0064] The acid treatment can be carried out, for example, by immersing the PAS in an acid or an aqueous solution of an acid, with stirring or heating if necessary. For example, when using acetic acid, a sufficient effect can be obtained by immersing the PAS powder in an aqueous solution of acetic acid at 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. In order to remove residual acid or salts from the acid-treated PAS, it is preferable to wash the PAS several times with water or warm water. The water used for washing is preferably distilled water or ion-exchanged water, so as not to impair the desired chemical modification effect of the PAS by the acid treatment.

[0065] Hot water treatment is carried out as follows: When treating PAS with hot water, the temperature of the hot water is preferably 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 preferred because the desired chemical modification of the PAS is less effective.

[0066] To achieve the desired chemical modification of PAS by hot water washing, it is preferable to use distilled water or ion-exchanged water. There are no particular restrictions on the hot water treatment procedure. It can be carried out by adding a specified amount of PAS to a specified amount of water, heating and stirring in a pressure vessel, or by continuous hot water treatment. The higher the water ratio of PPS resin to water, the better, but a bath ratio (weight of cleaning solution relative to dry PAS weight) of 200 g or less of PAS per liter of water is usually selected.

[0067] In addition, to avoid undesirable decomposition of the reactive functional groups at the terminals, it is desirable to carry out the treatment under an inert atmosphere.Furthermore, to remove any remaining components, it is preferable to wash the PAS after this hot water treatment several times with warm water.

[0068] When washing with an organic solvent, the procedure is as follows: There are no particular restrictions on the organic solvent used to wash the PAS, as long as it does not have the effect of decomposing the PAS. Examples of organic solvents that can be used to clean PAS include nitrogen-containing polar solvents such as N-methyl-2-pyrrolidone, dimethylformamide, dimethylacetamide, 1,3-dimethylimidazolidinone, hexamethylphosphoramide, and piperazinones; sulfoxide and 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, perchloroethylene, monochloroethane, dichloroethane, tetrachloroethane, perchloroethane, and chlorobenzene; alcohol and phenol solvents such as methanol, ethanol, propanol, butanol, pentanol, ethylene glycol, propylene glycol, phenol, cresol, polyethylene glycol, and polypropylene glycol; and aromatic hydrocarbon solvents such as benzene, toluene, and xylene. Among these organic solvents, it is particularly preferable to use N-methyl-2-pyrrolidone, acetone, dimethylformamide, chloroform, etc. These organic solvents may be used alone or in combination of two or more.

[0069] One method for washing with an organic solvent is to immerse the PAS in the organic solvent, with stirring or heating as necessary. There are no particular limitations on the washing temperature when washing the PAS with an organic solvent; any temperature between room temperature and approximately 300°C can be selected. While higher washing temperatures tend to increase the washing efficiency, a washing temperature between room temperature and 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. There are also no particular limitations on the washing time. While it depends on the washing conditions, a batch-type washing period of 5 minutes or more usually achieves sufficient results. Continuous washing is also possible. The post-treatment step preferably involves acid treatment, hot water treatment, or washing with an organic solvent, and a combination of two or more treatments is preferred from the perspective of impurity removal.

[0070] Examples of alkali metal or alkaline earth metal treatment methods include adding alkali metal salts or alkaline earth metal salts before, during, or after the pre-processing step; adding alkali metal salts or alkaline earth metal salts to the polymerization reactor before, during, or after the polymerization step; or adding alkali metal salts or alkaline earth metal salts at the beginning, middle, or end of the washing step. Among these, the easiest method is adding alkali metal salts or alkaline earth metal salts after removing residual oligomers and salts by organic solvent washing or warm or hot water washing. The alkali metal or alkaline earth metal is preferably introduced into the PAS in the form of an alkali metal ion or alkaline earth metal ion, such as acetate, hydroxide, or carbonate. Excess alkali metal salt or alkaline earth metal salt is preferably removed by washing with warm water or the like. The concentration of alkali metal ion or alkaline earth metal ion when introducing the alkali metal or alkaline earth metal is preferably 0.001 mmol or more per gram of PAS, and more preferably 0.01 mmol or more. The temperature is preferably 50°C or higher, more preferably 75°C or higher, and particularly preferably 90°C or higher. There is no particular upper limit to the temperature, but from the viewpoint of operability, a temperature of 280°C or lower is usually preferred. The bath ratio (weight of cleaning solution relative to weight of dry PAS) is preferably 0.5 or higher, more preferably 3 or higher, and even more preferably 5 or higher.

[0071] [Thermal oxidation crosslinking treatment] In addition, the PAS of the present invention can be used after being polymerized by a thermal oxidation crosslinking treatment, such as heating in an oxygen atmosphere after polymerization or heating with the addition of a crosslinking agent such as peroxide.

[0072] When dry heat treatment is performed for the purpose of increasing the molecular weight by thermal oxidative crosslinking, the temperature is preferably 160°C to 260°C, more preferably 170°C to 250°C. The oxygen concentration is desirably 5% by volume or more, and even more desirably 8% by volume or more. There is no particular upper limit to the oxygen concentration, but the limit is approximately 50% by volume. The treatment time is preferably 0.5 hours to 100 hours, more preferably 1 hour to 50 hours, and even more preferably 2 hours to 25 hours. The heat treatment device may be a conventional hot air dryer or a rotary or stirring blade-equipped heating device. For efficient and more uniform treatment, a rotary or stirring blade-equipped heating device is preferably used.

[0073] Dry heat treatment can also be performed to suppress thermal oxidative crosslinking and remove volatiles. The temperature is preferably 130°C to 250°C, more preferably 160°C to 250°C. In this case, the oxygen concentration is preferably less than 5% by volume, and even more preferably less than 2% by volume. The treatment time is preferably 0.5 to 50 hours, more preferably 1 to 20 hours, and even more preferably 1 to 10 hours. The heat treatment device may be a conventional hot air dryer or a rotary or stirring blade-equipped heating device. For efficient and more uniform treatment, it is more preferable to use a rotary or stirring blade-equipped heating device.

[0074] [Features of PAS] The amino group content of the PAS obtained in the present invention is preferably 80 μmol / g or more, more preferably 90 μmol / g or more, and even more preferably 100 μmol / g or more. Having an amino group content equal to or greater than the above lower limit is preferable because it results in a resin composition that is less susceptible to a decrease in tensile strength even after long-term hot water treatment. If the amino group content of the obtained PAS is less than 80 μmol / g, sufficient adhesion to different materials cannot be obtained, which is undesirable. There are no particular restrictions on the amino group content of the obtained PAS, but it is generally 500 μmol / g or less.

[0075] The amino group content in PAS can be determined by FT-IR analysis of PAS, for example, by measuring the 1900m -1It can be quantified by comparing the intensity of the absorption due to the amino group with the absorption around 3360 cm -1 The absorption of

[0076] The PAS obtained in the present invention preferably has a weight-average molecular weight of 30,000 or more, more preferably 34,000 or more, and even more preferably 38,000 or more. A weight-average molecular weight of less than 30,000 is undesirable because it may significantly impair strength and toughness during molding. There is no particular upper limit to the weight-average molecular weight of PAS, but a weight-average molecular weight exceeding 100,000 is undesirable because it reduces fluidity and is disadvantageous in terms of molding. The weight-average molecular weight referred to here is a value measured using gel permeation chromatography (GPC) with 1-chloronaphthalene as the eluent at a column temperature of 210°C and converted to a polystyrene standard.

[0077] [PAS usage] The PAS obtained by the present invention is preferably used in applications requiring adhesion to different materials such as resins other than PAS, fillers, and metals, more preferably in applications requiring adhesion to fillers, and even more preferably in applications requiring adhesion to glass fibers. The filler referred to here refers to fibrous fillers such as glass fibers, carbon fibers, carbon nanotubes, carbon nanohorns, potassium titanate whiskers, zinc oxide whiskers, calcium carbonate whiskers, wollastonite whiskers, aluminum borate whiskers, aramid fibers, alumina fibers, silicon carbide fibers, ceramic fibers, asbestos fibers, gypsum fibers, and metal fibers, or fullerenes, talc, wollastonite, zeolite, sericite, mica, kaolin, clay, pyrophyllite, silica, bentonite, asbestos, silicates such as alumina silicates, silicon oxides, Examples of fillers that can be used include metal compounds such as magnesium oxide, alumina, zirconium oxide, titanium oxide, and iron oxide; carbonates such as calcium carbonate, magnesium carbonate, and dolomite; sulfates such as calcium sulfate and barium sulfate; hydroxides such as calcium hydroxide, magnesium hydroxide, and aluminum hydroxide; and non-fibrous fillers such as glass beads, glass flakes, glass powder, ceramic beads, boron nitride, silicon carbide, carbon black, silica, and graphite. Among these, fibrous fillers such as glass fiber, carbon fiber, ceramic fiber, and aramid fiber are preferred, with glass fiber being more preferred. Furthermore, in order to introduce many functional groups onto the filler surface, it is preferable to pretreat the filler with a coupling agent such as an isocyanate compound, an organosilane compound, an organotitanate compound, an organoborane compound, or an epoxy compound.

[0078] In the present invention, adhesion to the filler can be improved by forming a covalent bond between the PAS and the filler. Examples of the covalent bond formed between the PAS and the filler include an ether bond, a urethane bond, an ester bond, an amide bond, an esteramide bond, an imide bond, and a urea bond, with the ether bond, amide bond, imide bond, and urea bond being preferred examples.

[0079] The PAS obtained in the present invention can be mixed with a filler by, for example, production in a molten state or production in a solution state, but from the viewpoint of simplicity, production in a molten state is preferred. For production in a molten state, melt kneading using an extruder or melt kneading using a kneader can be used, but from the viewpoint of productivity, melt kneading using an extruder that can produce continuously is preferred. For melt kneading using an extruder, one or more extruders can be used, such as a single-screw extruder, a twin-screw extruder, a multi-screw extruder such as a four-screw extruder, or a twin-screw single-screw composite extruder, but from the viewpoint of improving kneading ability, reactivity, and productivity, multi-screw extruders such as a twin-screw extruder and a four-screw extruder are preferably used, and melt kneading using a twin-screw extruder is most preferred.

[0080] The PAS obtained by the present invention has excellent heat resistance, chemical resistance, flame retardancy, electrical properties, and mechanical properties, and can be used not only for injection molding, injection compression molding, and blow molding, but also for extrusion molding into extrusion molded products such as sheets, films, fibers, and pipes.

[0081] The PAS of the present invention can be used in a wide range of applications, including electrical and electronic components such as sensors, LED lamps, connectors, sockets, resistors, relay cases, switches, coil bobbins, capacitors, variable capacitor cases, optical pickups, oscillators, various terminal boards, transformers, plugs, printed circuit boards, tuners, speakers, microphones, headphones, small motors, magnetic head bases, power modules, semiconductors, liquid crystal displays, FDD carriages, FDD chassis, motor brush holders, parabolic antennas, and computer-related components; VTR components, television components, irons, hair dryers, rice cooker components, microwave oven components, audio components, and audio equipment. Home and office electrical appliance parts such as audio equipment parts for audio equipment such as audio discs, laser discs (registered trademark), and compact discs, lighting parts, refrigerator parts, air conditioner parts, typewriter parts, and word processor parts; machine-related parts such as office computer parts, telephone parts, facsimile parts, copier parts, cleaning tools, motor parts, lighters, and typewriters; optical equipment and precision machinery parts such as microscopes, binoculars, cameras, and clocks; plumbing parts such as water faucet tops, mixer taps, pump parts, pipe joints, water volume control valves, relief valves, water temperature sensors, water volume sensors, and water meter housings;Valve alternator terminals, alternator connectors, IC regulators, potentiometer bases for light dimmers, various valves such as exhaust gas valves, various pipes for fuel, exhaust systems and intake systems, air intake nozzle snorkels, intake manifolds, fuel pumps, engine coolant joints, carburetor main bodies, carburetor spacers, exhaust gas sensors, coolant sensors, oil temperature sensors, throttle position sensors, crankshaft position sensors, air flow meters, brake pad wear sensors, thermostat bases for air conditioners, heating hot air flow control valves, brush holders for radiator motors, water pump impellers, turbine vanes, Examples of applications include wiper motor-related parts, distributors, starter switches, starter relays, transmission wire harnesses, windshield washer nozzles, air conditioner panel switch boards, fuel-related electromagnetic valve coils, fuse connectors, horn terminals, electrical component insulating plates, step motor rotors, lamp sockets, lamp reflectors, lamp housings, brake pistons, solenoid bobbins, engine oil filters, ignition device cases, vehicle speed sensors, cable liners, engine control unit cases, engine driver unit cases, capacitor cases, motor insulating materials, and hybrid car control system component cases, as well as various other automotive and vehicle-related parts. Among these, the material is particularly suitable for applications that may come into contact with hot water or coolant for extended periods, such as automotive cooling modules, automotive piping, residential piping, and water heater parts.

[0082] As a method for producing a PAS film using the PAS obtained by the present invention, a known melt film-forming method can be used, for example, a method in which the PAS is melted in a single-screw or twin-screw extruder, extruded through a film die, and cooled on a cooling drum to produce a film, or a biaxial stretching method in which the film thus produced is stretched lengthwise and widthwise using a roller-type longitudinal stretching device and a transverse stretching device called a tenter, but the method is not limited to these.

[0083] The PAS film obtained in this manner has excellent mechanical properties, electrical properties, and heat resistance, and can be suitably used in a variety of applications, such as as a dielectric film for film capacitors and chip capacitors, or as a release film.

[0084] The method for producing PAS fibers using the PAS obtained by the present invention can be a known melt spinning method. For example, the raw material PAS chips are fed into a single-screw or twin-screw extruder while being kneaded, and then the material is extruded from a spinneret through a polymer streamline exchanger and a filtration layer installed at the tip of the extruder, followed by cooling, stretching, and heat setting. However, the method is not limited to these methods.

[0085] The PAS monofilaments or short fibers thus obtained can be suitably used in various applications such as papermaking dryer canvases, net conveyors, and bag filters. [Example]

[0086] The method of the present invention will be explained in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples alone.

[0087] [Analysis of amino group content] The content of amino groups introduced into PAS was measured by FT-IR (IR-810 infrared spectrophotometer manufactured by JASCO Corporation) of an amorphous film of PAS prepared by quenching from a molten state, and the 1900 cm -1 The quantification was carried out by comparing the intensity of the absorption due to the amino group with the absorption around 3360 cm. -1 The absorption of

[0088] [Molecular weight measurement] The weight-average molecular weight (Mw) of PAS was calculated in terms of polystyrene using gel permeation chromatography (GPC), a type of size exclusion chromatography (SEC). The GPC measurement conditions are shown below. Equipment: Senshu Science SSC-7110 Column name: Shodex UT806M x 2 Eluent: 1-chloronaphthalene Detector: Differential refractive index detector Column temperature: 210℃ Pre-thermostat temperature: 250℃ Pump thermostatic bath temperature: 50℃ Detector temperature: 210℃ Flow rate: 1.0mL / min Sample injection volume: 300 μL.

[0089] [Analysis of remaining amount of amino group-containing monomers] The amount of compound (A) remaining in the polymerization reaction product obtained after the polymerization step was determined using a gas chromatograph GC-2010PLUS manufactured by Shimadzu Corporation, and the remaining rate was calculated from the charged amount.

[0090] [Example 1] A 70-liter autoclave equipped with a stirrer and a bottom stop valve was charged with 8.26 kg (70.00 mol) of 47.5% sodium hydrosulfide, 3.08 kg (73.89 mol) of 96% sodium hydroxide, 14.57 kg (147.00 mol) of N-methyl-2-pyrrolidone (NMP), 1.89 kg (23.10 mol) of sodium acetate, and 5.65 kg of ion-exchanged water, and gradually heated to 225°C over approximately 3 hours at atmospheric pressure while passing nitrogen through. Heating was stopped and cooling was initiated when 9.99 kg of water and 0.28 kg of NMP had distilled off. At this point, the amount of hydrogen sulfide released was 1.40 mol, and the amount of inorganic sulfidizing agent in the system after this step was 68.60 mol.

[0091] The mixture was then cooled to 200°C, and 10.24 kg (69.64 mol) of p-dichlorobenzene (p-DCB), 0.089 kg (0.71 mol) of 4-aminothiophenol, and 5.55 kg (56.00 mol) of NMP were added. The reaction vessel was then sealed under nitrogen gas and heated from 200°C to 218°C at a rate of 1.0°C / min while stirring at 240 rpm. The mixture was then heated from 218°C to 234°C at a rate of 0.6°C / min, from 234°C to 240°C at a rate of 0.25°C / min, and from 240°C to 276°C at a rate of 0.8°C / min.

[0092] Next, 1.01 g (56.00 mol) of ion-exchanged water was injected into the reaction vessel and reacted at 276°C for 60 minutes. After that, the bottom plug valve of the autoclave was opened, and the contents were flushed into a vessel equipped with a stirrer over 15 minutes while pressurizing with nitrogen, and the contents were stirred for a while at 250°C to remove most of the NMP.

[0093] The recovered material and 76 L of ion-exchanged water were placed in an autoclave equipped with a stirrer and washed at 75°C for 15 minutes. The cake was then filtered to obtain a cake. The resulting cake was washed with 75°C ion-exchanged water for 15 minutes and filtered three times. The cake and 76 L of ion-exchanged water were then placed in an autoclave equipped with a stirrer. The autoclave was then purged with nitrogen and heated to 195°C. The autoclave was then cooled, and the contents were removed. The contents were filtered to obtain a cake. The resulting cake was dried at 120°C for 4 hours under a nitrogen stream to obtain dried PAS. The weight-average molecular weight of this PAS was 34,000. FT-IR spectroscopy confirmed that this PAS contained phenylene sulfide units as structural units and 95 μmol / g of amino groups. The 4-aminothiophenol added reacted completely, with none remaining in the polymerization product.

[0094] [Example 2] Polymerization and washing were carried out in the same manner as in Example 1, except that the heating rate from 234°C to 240°C was changed to 0.04°C / min. The weight-average molecular weight of the resulting PAS was 39,000. FT-IR spectrum confirmed that this PAS had phenylene sulfide units as structural units and contained 95 μmol / g of amino groups. The entire amount of 4-aminothiophenol charged reacted, and none remained in the polymerization reaction product.

[0095] [Example 3] Polymerization and washing were carried out in the same manner as in Example 2, except that the amount of 96% sodium hydroxide was changed to 3.07 kg (73.60 mol), the amount of 4-aminothiophenol was changed to 0.071 kg (0.56 mol), and the amount of p-dichlorobenzene (p-DCB) was changed to 10.23 kg (69.57 mol). The weight-average molecular weight of the resulting PAS was 42,000. FT-IR spectrum confirmed that this PAS contained phenylene sulfide units as structural units and 76 μmol / g of amino groups. The entire amount of 4-aminothiophenol charged reacted, and none remained in the polymerization reaction mixture.

[0096] [Example 4] Polymerization and washing were carried out in the same manner as in Example 2, except that the amount of 96% sodium hydroxide was changed to 3.14 kg (75.36 mol), the amount of 4-aminothiophenol was changed to 0.18 kg (1.43 mol), and the amount of p-dichlorobenzene (p-DCB) was changed to 10.29 kg (70.00 mol). The weight-average molecular weight of the resulting PAS was 31,000. FT-IR spectrum confirmed that this PAS contained phenylene sulfide units as structural units and 180 μmol / g of amino groups. The entire amount of 4-aminothiophenol charged reacted, and none remained in the polymerization reaction mixture.

[0097] [Example 5] Polymerization and washing were carried out in the same manner as in Example 2, except that the amount of sodium acetate added was changed to 3.45 kg (42.00 mol). The weight-average molecular weight of the resulting PAS was 39,000. FT-IR spectroscopy confirmed that this PAS had phenylene sulfide units as structural units and contained 95 μmol / g of amino groups. The entire amount of 4-aminothiophenol charged reacted, and none remained in the polymerization reaction mixture.

[0098] [Example 6] After heating to 276°C, polymerization and washing were carried out in the same manner as in Example 1, except that ion-exchanged water was not pressure-charged into the reaction vessel. The weight-average molecular weight of the resulting PAS was 31,000. FT-IR spectrum confirmed that this PAS had phenylene sulfide units as structural units and contained 95 μmol / g of amino groups. The entire amount of 4-aminothiophenol charged reacted, and none remained in the polymerization reaction mixture.

[0099] [Example 7] After heating to 276°C, polymerization and washing were carried out in the same manner as in Example 2, except that ion-exchanged water was not pressure-charged into the reaction vessel. The weight-average molecular weight of the resulting PAS was 35,000. FT-IR spectrum confirmed that this PAS had phenylene sulfide units as structural units and contained 95 μmol / g of amino groups. The entire amount of 4-aminothiophenol charged reacted, and none remained in the polymerization reaction product.

[0100] [Comparative Example 1] Polymerization and washing were carried out in the same manner as in Example 6, except that the amount of 96% sodium hydroxide was changed to 3.02 kg (72.45 mol), the amount of 4-aminothiophenol was changed to 0.044 kg (0.35 mol), and the amount of p-dichlorobenzene (p-DCB) was changed to 10.19 kg (69.29 mol). The weight-average molecular weight of the resulting PAS was 38,000. FT-IR spectrum confirmed that this PAS contained phenylene sulfide units as structural units and 46 μmol / g of amino groups. The entire amount of 4-aminothiophenol charged reacted, and none remained in the polymerization reaction mixture.

[0101] Comparative Example 2 Polymerization and washing were carried out in the same manner as in Example 6, except that sodium acetate was not added. The weight-average molecular weight of the resulting PAS was 23,000. FT-IR spectrum confirmed that this PAS had phenylene sulfide units as structural units and contained 95 μmol / g of amino groups. The entire amount of 4-aminothiophenol charged reacted, and none remained in the polymerization reaction mixture.

[0102] Comparative Example 3 A 70-liter autoclave equipped with a stirrer and a bottom stop valve was charged with 8.26 kg (70.00 mol) of 47.5% sodium hydrosulfide, 3.08 kg (73.89 mol) of 96% sodium hydroxide, 14.57 kg (147.00 mol) of N-methyl-2-pyrrolidone (NMP), 1.89 kg (23.10 mol) of sodium acetate, and 5.65 kg of ion-exchanged water, and gradually heated to 225°C over approximately 3 hours at atmospheric pressure while passing nitrogen through. Heating was stopped and cooling was initiated when 9.99 kg of water and 0.28 kg of NMP had distilled off. At this point, the amount of hydrogen sulfide released was 1.40 mol, and the amount of inorganic sulfidizing agent in the system after this step was 68.60 mol.

[0103] The autoclave was then cooled to 200°C, and 10.24 kg (69.64 mol) of p-dichlorobenzene (p-DCB), 0.089 kg (0.71 mol) of 4-aminothiophenol, and 5.55 kg (56.00 mol) of NMP were added. The reaction vessel was then sealed under nitrogen gas and heated from 200°C to 218°C at a rate of 1.0°C / min with stirring at 240 rpm. The temperature was then increased from 218°C to 234°C at a rate of 0.6°C / min, from 234°C to 240°C at a rate of 0.25°C / min, and from 240°C to 270°C at a rate of 0.8°C / min. Upon reaching 270°C, the bottom stop valve of the autoclave was opened, and the contents were flushed into a vessel equipped with a stirrer over 15 minutes while pressurizing with nitrogen. The contents were then stirred at 250°C for a period of time to remove most of the NMP.

[0104] Subsequent washing was carried out in the same manner as in Example 1. The weight-average molecular weight of the resulting PAS was 15,000. FT-IR spectrum confirmed that this PAS had phenylene sulfide units as structural units and contained 95 μmol / g of amino groups. The entire amount of 4-aminothiophenol charged reacted, and none remained in the polymerization reaction product.

[0105] Comparative Example 4 A 70-liter autoclave equipped with a stirrer and a bottom stop valve was charged with 8.26 kg (70.00 mol) of 47.5% sodium hydrosulfide, 3.08 kg (73.89 mol) of 96% sodium hydroxide, 14.57 kg (147.00 mol) of N-methyl-2-pyrrolidone (NMP), 1.89 kg (23.10 mol) of sodium acetate, and 5.65 kg of ion-exchanged water, and gradually heated to 225°C over approximately 3 hours at atmospheric pressure while passing nitrogen through. Heating was stopped and cooling was initiated when 9.99 kg of water and 0.28 kg of NMP had distilled off. At this point, the amount of hydrogen sulfide released was 1.40 mol, and the amount of inorganic sulfidizing agent in the system after this step was 68.60 mol.

[0106] The mixture was then cooled to 200°C, and 10.24 kg (69.64 mol) of p-dichlorobenzene (p-DCB) and 5.55 kg (56.00 mol) of NMP were added. The reaction vessel was then sealed under nitrogen gas and heated from 200°C to 218°C at a rate of 1.0°C / min while stirring at 240 rpm. The mixture was then heated from 218°C to 234°C at a rate of 0.6°C / min, from 234°C to 240°C at a rate of 0.25°C / min, and from 240°C to 276°C at a rate of 0.8°C / min, and then reacted at 276°C for 50 minutes. The bottom stopper valve was slightly opened to sample a small amount of the contents, and the weight-average molecular weight was confirmed to be 42,000.

[0107] Next, 0.089 kg (0.71 mol) of 4-aminothiophenol and 0.69 kg (7.00 mol) of NMP were pressure-charged into the reaction vessel, and the reaction was further carried out at 276°C for 60 minutes. After that, the bottom plug valve of the autoclave was opened, and the contents were flushed into a vessel equipped with a stirrer over 15 minutes while pressurizing with nitrogen, and the contents were stirred for a while at 250°C to remove most of the NMP.

[0108] Subsequent washing was carried out in the same manner as in Example 1. The weight-average molecular weight of the resulting PAS was 10,000. FT-IR spectroscopy confirmed that this PAS had phenylene sulfide units as structural units and contained 95 μmol / g of amino groups. The entire amount of 4-aminothiophenol charged reacted, and none remained in the polymerization reaction product.

[0109] The results of the above-mentioned Examples and Comparative Examples will be compared and explained.

[0110] As shown in Examples 1 to 7, according to the production method of the present invention, a PAS having a high amino group content and a high molecular weight was obtained simply and efficiently without leaving any amino group-containing monomer remaining in the polymerization reaction product.

[0111] In particular, in Examples 2 to 5 and 7, the polymerization time, including the temperature rise and fall time, was 3 hours or more and 4 hours or less within the temperature range of 200°C or more and 240°C or less, and therefore PAS having both a high amino group content and a high molecular weight was obtained.

[0112] Furthermore, in Examples 2, 3, and 5, by having 1.5 moles or more and 1.8 moles or less of water present in the reaction vessel per mole of inorganic sulfidizing agent within the temperature range of 265°C or more and less than 280°C (Step 2), a PAS with excellent initial strength was obtained when molded into a molded product.

[0113] In Comparative Example 1, the amount of 4-aminothiophenol in the reaction vessel was less than 0.008 moles per mole of inorganic sulfidizing agent, and therefore the weight-average molecular weight of the resulting PAS was high, but the amino group content of the resulting PAS was low.

[0114] In Comparative Example 2, the amount of sodium acetate was less than 0.01 mole per mole of the inorganic sulfidizing agent, and therefore the weight-average molecular weight of the obtained PAS was low.

[0115] In Comparative Example 3, after step 1, step 2 was not included, and therefore the weight-average molecular weight of the PAS obtained was extremely low.

[0116] In Comparative Example 4, step 1 was carried out without 4-aminothiophenol, and then 4-aminothiophenol was added to the reaction vessel during step 2, resulting in a PAS with an extremely low weight-average molecular weight.

[0117] [Table 1]

Claims

1. A method for producing polyarylene sulfide by reacting an inorganic sulfidizing agent, a dihalogenated aromatic compound, and compound (A) in an organic polar solvent in the presence of an alkali metal hydroxide, the method comprising the steps of: making compound (A) present in a reaction vessel in an amount of 0.008 moles or more per mole of the inorganic sulfidizing agent; compound (A) having at least one aromatic ring and having, on said aromatic ring, a reactive functional group consisting of an amino 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; and comprising the steps 1 and 2 below, wherein in step 2, 1 mole or more and 1.8 moles or less of water are present in the reaction vessel per mole of the inorganic sulfidizing agent; and wherein the weight-average molecular weight of the polyarylene sulfide is 30,000 or more. Step 1: A step of producing a polyarylene sulfide prepolymer by subjecting an inorganic sulfidizing agent, a dihalogenated aromatic compound, and compound (A) to polymerization in the presence of an alkali metal hydroxide in an organic polar solvent at a temperature of 200°C or higher and 240°C or lower for a polymerization time of 1 hour or higher and 4 hours or lower, including the time for temperature increase and decrease. Step 2: Following step 1, a step of obtaining polyarylene sulfide from the prepolymer within a temperature range of 265°C or higher and lower than 280°C.

2. 2. The method for producing polyarylene sulfide according to claim 1, wherein the alkali metal carboxylate is present in an amount of 0.01 mole or more and 1 mole or less per mole of the inorganic sulfidizing agent.

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