Method for producing polyarylene sulfide copolymer

Abstract

To provide a production method of a polyarylene sulfide (PAS), with which the PAS having many amino groups introduced in its molecular chain is simply and efficiently provided, and further in the case of producing a PAS copolymer by using a PAS having amino groups, the PAS copolymer with higher molecular weight can be obtained.SOLUTION: In a production method of a PAS, in which at least a dihalogenated aromatic compound, an inorganic sulfidation agent, and a compound A are made to react with one another in an organic polar solvent and in the presence of an alkali metal hydroxide, the compound A of 0.04-0.5 mol is made to exist in a reaction vessel based on the inorganic sulfidation agent of 1 mol, the compound A is a compound having at least one aromatic ring and having at least one functional group selected from an amino group, a hydroxy group, a salt of the hydroxy group, a thiol group, and a salt of the thiol group on the one aromatic ring, and a cleaning step with a solution of pH 8 or less is included in an after treatment step.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] Polyarylene sulfides, typified by polyphenylene sulfide (hereinafter sometimes abbreviated as PPS), have properties suitable for engineering plastics, such as excellent heat resistance, barrier properties, moldability, chemical resistance, electrical insulation, and moist heat resistance, and are used primarily in injection molding and extrusion molding for a variety of electrical and electronic parts, machine parts, automotive parts, films, fibers, etc. Due to their excellent properties, the range of applications for polyarylene sulfides has been expanding in recent years.

[0003] On the other hand, polyarylene sulfide has few functional groups in its molecular chain, and therefore has poorer interaction and reactivity than other engineering plastics such as polyamides and polyesters, making it difficult to bond or composite with different materials. It is well known that the introduction of highly polar amino groups into the polymer improves adhesion to glass fiber, which is widely used as a polymer reinforcement material. This also promises to improve adhesion to carbon fiber, which has hydroxyl groups on the fiber surface, and compatibility with polymers with reactive functional groups other than amino groups, such as hydroxyl groups, isocyanate groups, and epoxy groups, as well as the heat resistance and strength of copolymers synthesized from them.

[0004] For this reason, many studies have been conducted on introducing reactive functional groups into polyarylene sulfides. For example, Patent Document 1 discloses a method for producing polyarylene sulfides having reactive functional groups using an aromatic thiol. Patent Document 2 discloses a method for producing modified polyarylene sulfides having excellent thermal stability using an aromatic thiol and a polyhaloaromatic compound as a polymerization aid. Patent Document 3 discloses a method for producing polyarylene sulfides having amino groups by mixing and heating an alkali metal sulfide and a functional group-containing halo-substituted aromatic compound before reacting the alkali metal sulfide with a dihaloaromatic compound. Patent Document 4 discloses a method for producing polyarylene sulfides having reactive functional groups by heating a cyclic arylene sulfide with a sulfur-containing compound having reactive functional groups.

[0005] Polyarylene sulfides having reactive functional groups are also useful as prepolymers for obtaining polyarylene sulfide copolymers, and Patent Document 5 discloses polyarylene sulfide copolymers obtained by reacting polyarylene sulfides having reactive functional groups with rigid molecules.

[0006] Furthermore, as a method for removing oligomer components in a polyarylene sulfide resin, Patent Document 6 discloses a method for producing polyarylene sulfide, which includes a step of washing a solid content containing polyarylene sulfide with water and a step of washing the polyarylene sulfide with an organic solvent. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2020-084027 [Patent Document 2] Patent Publication No. 2021-147513 [Patent Document 3] Japanese Patent Application Publication No. 7-102064 [Patent Document 4] International Publication No. 2012 / 057319 [Patent Document 5] International Publication No. 2019 / 151288 [Patent Document 6] International Publication No. 2021 / 200332 Summary of the Invention [Problem to be solved by the invention]

[0008] However, although the methods disclosed in Patent Documents 1 and 2 can introduce amino groups into the molecular chain of the polyarylene sulfide provided, the amount of amino groups introduced is small and cannot be said to be sufficient. In the method disclosed in Patent Document 3, amino groups are introduced into the main chain, which reduces the frequency of contact with the reaction target and prevents the reactivity from being utilized, resulting in an insufficient molecular design. In the method disclosed in Patent Document 4, amino groups can be introduced into polyarylene sulfide, but the method involves many steps and cannot be said to be simple.

[0009] In the method for producing a polyarylene sulfide copolymer disclosed in Patent Document 5, the polyarylene sulfide that becomes the prepolymer may contain impurities, and it has been desired to achieve both a reduction in the amount of gas generated during the heat processing required for producing the polyarylene sulfide copolymer and an increase in the molecular weight of the resulting polyarylene sulfide copolymer.

[0010] In the method for producing polyarylene sulfide disclosed in Patent Document 6, polyarylene sulfide is washed with water and an organic solvent, but the polyarylene sulfide in Patent Document 6 is not one in which an amino group has been introduced into the molecular chain, but is a polyarylene sulfide with a relatively high molecular weight, and the purpose of the method is to reduce relatively low-volatility oligomer components that become impurities that cause mold fouling during molding processing, and there is no description regarding the production of polyarylene sulfide copolymers or the molecular weight of polyarylene sulfide copolymers.

[0011] An object of the present invention is to simply and efficiently provide a polyarylene sulfide having many amino groups introduced into the molecular chain. Another object of the present invention is to provide a production method for obtaining an amino group-containing polyarylene sulfide with few impurities and using it as a prepolymer, thereby producing a polyarylene sulfide copolymer with a high molecular weight and with little gas generation. [Means for solving the problem]

[0012] 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. A method for producing polyarylene sulfide by reacting at least a dihalogenated aromatic compound, an inorganic sulfidizing agent, 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 0.04 mol to 0.5 mol per mol of the inorganic sulfidizing agent, and compound (A) has at least one aromatic ring and has an amino group and a hydroxyl group on the aromatic ring. ,blood Oar Motoo and a salt of a thiol group, wherein at least a portion of compound (A) is added to a reaction vessel at the same stage as the addition of a dihalogenated aromatic compound to the reaction vessel, and the post-treatment step includes a washing step with a solution of pH 8 or less. and a washing step using an organic solvent selected from N-methyl-2-pyrrolidone, dimethylformamide, and chloroform. A method for producing polyarylene sulfide, comprising: A method for producing a polyarylene sulfide copolymer, comprising obtaining a polyarylene sulfide by the above procedure, mixing it with at least one compound (B) selected from the following formulae (a) to (u), and then heating the resulting mixture:

[0013] [ka]

[0014] TIFF0007800209000002.tif81168

[0015] (wherein X is any one selected from the group consisting of a carboxyl group, a silanol group, a sulfonic acid group, an acid anhydride group, an isocyanate group, an aldehyde group, an epoxy group, and an alkoxysilane group. R, R 1 , and R 2 is a substituent selected from hydrogen, an alkyl group having 1 to 12 carbon atoms, an aryl group having 6 to 24 carbon atoms, and a halogen group; R, R 1 , and R 2 may be the same or different.) 2. A method for producing a polyarylene sulfide copolymer according to 1 above, characterized in that the method comprises a step of washing with an organic solvent after the step of washing with a solution having a pH of 8 or less. [Effects of the Invention]

[0016] According to the present invention, polyarylene sulfide having many amino groups introduced into the molecular chain can be efficiently provided by a simple method. Furthermore, the polyarylene sulfide having amino groups produced by the production method of the present invention is characterized by generating a small amount of gas when heated. When polyarylene sulfide is obtained by the production method of the present invention, mixed with a reactive compound, and then heated to produce a polyarylene sulfide copolymer, the amount of gas generated during heating is reduced, thereby improving workability. Furthermore, when the polyarylene sulfide copolymer is produced using the polyarylene sulfide having amino groups produced by the production method of the present invention, a polyarylene sulfide copolymer with a higher molecular weight can be obtained. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, embodiments of the present invention will be described in detail.

[0018] The polyarylene sulfide according to an embodiment of the present invention is a homopolymer or copolymer having a repeating unit of 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 includes units represented by the following formulas (I) to (XI), among which the unit represented by formula (I) is particularly preferred.

[0019] [ka]

[0020] (R 3 ,R 4 is a substituent selected from hydrogen, an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, an aryl group having 6 to 24 carbon atoms, a halogen group, and a reactive functional group; R 3 and R 4 may be the same or different) 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 (XII) to (XIV), 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.

[0021] [ka]

[0022] (Here, Ar is a unit represented by the above formula (I) to formula (XI).) Another preferred embodiment is a polyarylene sulfide having an amino group bonded to the above-mentioned Ar. The amino group is a structure derived from the compound (A), and details will be described later. The position of the amino group may be in the main chain of the polyarylene sulfide or at the terminal, but terminal introduction is preferred because it is easier to control the reaction with other polymers or compounds having reactive functional groups. In the case of terminal introduction, the position is preferably p-position relative to the S bonded to Ar.

[0023] Furthermore, the polyarylene sulfide in the embodiment of the present invention may be any of a random copolymer, a block copolymer, and a mixture thereof containing the above repeating unit.

[0024] Representative examples of these include polyphenylene sulfide, polyphenylene sulfide sulfone, polyphenylene sulfide ketone, random copolymers thereof, block copolymers thereof, and mixtures thereof. Particularly preferred polyarylene sulfides include those containing p-phenylene sulfide units as the main structural unit of the polymer.

[0025] [ka]

[0026] Examples of suitable polyphenylene sulfides include polyphenylene sulfides containing 80 mol % or more, particularly 90 mol % or more of the above.

[0027] The method for producing the polyarylene sulfide of the present invention will be specifically described below, but is not limited to the following method.

[0028] First, the raw materials used in the production of polyarylene sulfide will be described.

[0029] [Inorganic sulfidizing agent] The inorganic sulfidizing agent used in the method for producing polyarylene sulfide 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] [Compound (A)] The compound (A) used in the polyarylene sulfide production method of the present invention is a compound having at least one aromatic ring and, on the aromatic ring, an amino group and at least one functional group selected from a hydroxyl group, a hydroxyl salt, a thiol group, and a thiol salt. Compound (A) may be any aromatic compound having an amino group to be introduced into the polyarylene sulfide and a hydroxyl group, a hydroxyl salt, a thiol group, or a thiol salt that reacts with a dihalogenated aromatic compound in the polymerization reaction step described below. Specific examples of preferred compounds include 2-aminophenol, 4-aminophenol, 3-aminophenol, 2-aminothiophenol, 4-aminothiophenol, 3-aminothiophenol, and compounds in which the hydroxyl group or thiol group of these compounds is a salt of an alkali metal or alkaline earth metal. From the viewpoint of reactivity, 4-aminophenol and 4-aminothiophenol are particularly preferred. Two or more different compounds (A) 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 (A), it is a preferred embodiment to simultaneously use an equivalent amount of an alkali metal hydroxide. When a compound in which a hydroxyl group or a thiol group is in the form of a salt is used as compound (A), 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.

[0035] The lower limit of the amount of compound (A) used is 0.04 mol or more, preferably 0.05 mol or more, more preferably 0.06 mol or more, even more preferably 0.08 mol or more, and even more preferably 0.1 mol or more, per mol of the inorganic sulfidizing agent added. A use amount of this value or more is preferred because it allows sufficient introduction of amino groups into the polyarylene sulfide. The upper limit of the amount of compound (A) used is 0.5 mol or less, more preferably 0.45 mol or less, and even more preferably 0.4 mol or less, per mol of the inorganic sulfidizing agent added. A use amount of this value or less is preferred because it prevents a decrease in the molecular weight of the polyarylene sulfide and a decrease in its mechanical properties.

[0036] The timing of adding compound (A) is not particularly specified, and compound (A) 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 may be added in multiple batches. However, from the viewpoint of efficiently reacting compound (A) with the dihalogenated aromatic compound, it is more preferable to add compound (A) at the same stage as the addition of the dihalogenated aromatic compound to the reaction vessel.

[0037] [Dihalogenated aromatic compound] Examples of dihalogenated aromatic compounds used in the method for producing polyarylene sulfide 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 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 mainly composed of p-dihalogenated benzenes, such as p-dichlorobenzene, are preferred. Particularly preferably, it contains 80 to 100 mol % of p-dichlorobenzene, and more preferably 90 to 100 mol %. It is also possible to use a combination of two or more different dihalogenated aromatic compounds.

[0038] 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 (A) substance amount] indicate the amount of each compound used when producing polyarylene sulfide. [Monomer ratio] = [Amount of dihalogenated aromatic compound] / ([Amount of inorganic sulfidizing agent] + [Amount of compound (A)])

[0039] [Organic polar solvents] Preferred examples of organic polar solvents used in the polyarylene sulfide 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 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.

[0040] The amount of organic polar solvent used is preferably 2.0 mol or more, more preferably 2.2 mol or more, and even more preferably 2.3 mol or more, per mol of inorganic sulfidizing agent charged. A use amount of this value or more is preferred because polyarylene sulfide can be synthesized in good yield. Furthermore, the amount of organic polar solvent used is preferably 6.0 mol or less, more preferably 5.0 mol or less, and even more preferably 4.0 mol or less, per mol of inorganic sulfidizing agent charged. A use amount of this value or less is preferred because gas generation upon heating of the resulting polyarylene sulfide can be reduced.

[0041] [Polymerization aid] In one preferred embodiment, a polymerization aid is used to obtain a polyarylene sulfide with a relatively high degree of polymerization in a shorter time. 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, with alkali metal carboxylates being preferred as the organic carboxylates and lithium chloride being preferred as the alkali metal chlorides.

[0042] 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, and mixtures thereof.

[0043] 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.

[0044] When these alkali metal carboxylates are used as polymerization aids, the amount used is usually in the range of 0.01 mol to 2 mol per mol of the charged inorganic sulfidizing agent, and in terms of obtaining a higher degree of polymerization, the range of 0.1 mol to 0.6 mol is preferred, and the range of 0.2 mol to 0.5 mol is more preferred.

[0045] When water is used as a polymerization aid, the amount added is usually in the range of 0.3 mol to 15 mol per mol of the charged inorganic sulfidizing agent, and in terms of obtaining a higher degree of polymerization, the range of 0.6 mol to 10 mol is preferred, and the range of 1 mol to 5 mol is more preferred.

[0046] 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.

[0047] 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.

[0048] [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.

[0049] 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.

[0050] 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.

[0051] Next, a preferred method for producing the polyarylene sulfide 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 method is not limited to this method.

[0052] [Pre-process] In the method for producing polyarylene sulfide, 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.

[0053] As mentioned above, inorganic sulfidizing agents can also be used that are prepared in situ in the reaction system or in a separate vessel from the polymerization vessel from an alkali metal hydrosulfide and an alkali metal hydroxide. While there are no particular limitations on this method, a preferred method involves adding an alkali metal hydrosulfide and an 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 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 (A) may be added. Toluene or the like may be added to facilitate the distillation of water during the reaction.

[0054] At the end of the pre-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 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.

[0055] [Polymerization reaction process] Polyarylene sulfide is produced by reacting at least an inorganic sulfidizing agent, a dihalogenated aromatic compound, and compound (A) in an organic polar solvent within a temperature range of 200°C or higher and lower than 290°C.

[0056] To start the polymerization reaction, an organic polar solvent, a 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 be added at this stage. These raw materials may be added in any order, or simultaneously.

[0057] The mixture is usually heated to a temperature in the range of 200° C. to less than 290° C. There are no particular restrictions on the temperature increase rate, but a rate of 0.01° C. / min to 5° C. / min is usually selected, and a range of 0.1° C. / min to 3° C. / min is more preferred.

[0058] In general, the temperature is finally raised to 250° C. to less than 290° C., and the reaction is carried out at that temperature for usually 0.25 to 50 hours, preferably 0.5 to 20 hours.

[0059] A method of reacting at 200° C. to 260° C. for a certain period of time before reaching the final temperature, and then raising the temperature to 270° C. to less than 290° C., is effective in obtaining a higher degree of polymerization. In this case, the reaction time at 200° C. to 260° C. is usually selected from the range of 0.25 to 20 hours, and preferably from the range of 0.25 to 10 hours.

[0060] In order to adjust the molecular weight of the polymer, it is possible to add compound (A) during the polymerization. However, from the viewpoint of efficient reaction of compound (A), it is more preferable to add at least a part of compound (A) at the same stage as the dihalogenated aromatic compound.

[0061] [Recovery process] In the method for producing polyarylene sulfide, after the polymerization is completed, a solid is recovered from the polymerization reaction product containing the polymer, the solvent, etc. Any known recovery method may be used.

[0062] 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.

[0063] 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.

[0064] [Post-processing process] After polyarylene sulfide is produced through the above-mentioned polymerization reaction step and recovery step, it can be subjected to post-treatment steps such as acid treatment, hot water treatment, and washing with an organic solvent. In the post-treatment step of the present invention, a washing step with a solution of pH 8 or less is carried out.

[0065] An acid is used to wash polyarylene sulfide with a solution having a pH of 8 or less. The acid used is not particularly limited as long as it does not have the effect of decomposing polyarylene sulfide, and examples thereof include acetic acid, hydrochloric acid, sulfuric acid, phosphoric acid, silicic acid, carbonic acid, and propylic acid. Among these, acetic acid and hydrochloric acid are more preferably used. On the other hand, acids such as nitric acid that decompose and deteriorate polyarylene sulfide are not preferred.

[0066] Washing with a solution having a pH of 8 or less can be performed, for example, by immersing the polyarylene sulfide in an acid or an acid solution, with stirring or heating possible if necessary. When an acid solution is used, the solution may be an organic solvent solution or an aqueous solution, but an aqueous solution is preferred from the viewpoint of the miscibility of the acid and the tendency for the solubility of salts and basic components contained in the 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 the polyarylene sulfide. For example, when acetic acid is used, a sufficient effect can be obtained by immersing the polyarylene sulfide powder in an aqueous acetic acid solution whose pH has been adjusted and heated to 80°C to 200°C, and stirring for 30 minutes.

[0067] The upper limit of the pH of the solution to be washed is 8 or less, preferably 7 or less, more preferably 6 or less, even more preferably 5 or less, and particularly preferably 4 or less. From the viewpoint of the washing effect, a lower pH is desirable, but from the viewpoint of the ease of handling of the acid used and the prevention of degradation of the polyarylene sulfide, the lower limit of the pH is preferably 1 or more, more preferably 2 or more, and even more preferably 3 or more. Here, the pH of the solution to be washed refers to the pH of the solution in which the polyarylene sulfide is immersed. To measure the pH of the solution to be washed, for example, a solution in which the polyarylene sulfide is immersed can be used. If filtration is performed after washing, the pH of the filtrate can also be considered to be the same as the pH of the solution in which the polyarylene sulfide is immersed, so the filtrate may also be used. As a method for measuring the pH of the solution to be washed, a general method can be used, for example, a pH meter with a glass electrode, a hydrogen electrode, an indicator, or litmus paper can be used.

[0068] When a polyarylene sulfide copolymer is obtained using the amino group-containing polyarylene sulfide obtained by the production method of the present invention, washing with a solution of pH 8 or less makes it possible to obtain a polyarylene sulfide copolymer with a higher molecular weight than when washing with a solution of pH 8 or less is not performed. The reason why a polyarylene sulfide copolymer with a higher molecular weight is obtained is not clear, but it is thought that this is because the removal of basic components contained in the polyarylene sulfide allows the compound (B), which will be described later, to react efficiently with the amino groups of the polyarylene sulfide.

[0069] In order to remove any acid or salt remaining in the polyarylene sulfide that has been washed with a solution having a pH of 8 or less, it is preferable to further wash the polyarylene sulfide 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 effect of chemical modification of the polyarylene sulfide.

[0070] In the post-treatment step, washing with an organic solvent is also preferred. Washing with an organic solvent is as follows. There are no particular limitations on the organic solvent used to wash polyarylene sulfide, 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 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, etc. are preferred. Furthermore, from the viewpoint of removing impurities having an arylene sulfide structure, 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, or may be mixed with water.

[0071] An example of a method for washing with an organic solvent is to immerse the polyarylene sulfide in the organic solvent, and stirring or heating can be performed as necessary. There are no particular limitations on the washing temperature when washing the polyarylene sulfide with an organic solvent, and any temperature from room temperature to about 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. There are also no particular limitations on the washing time. Although it depends on the washing conditions, in the case of batch washing, washing for 5 minutes or more usually achieves sufficient results. Continuous washing is also possible. It is effective to combine washing with an organic solvent and washing with a solution of pH 8 or less. Using these in combination reduces the amount of gas generated when the polyarylene sulfide is heated, and is also preferred because a high molecular weight product can be easily obtained when the polyarylene sulfide is used to produce the polyarylene sulfide copolymer described below. Although the reasons for these are unclear, it is thought that the removal of impurities reduces the amount of compounds that cause gas and increases the proportion of amino groups present at the terminals of the polyarylene sulfide, making the copolymerization reaction more likely to occur. The order of washing with a solution of pH 8 or less and washing with an organic solvent may be any, but it is thought that impurities can be removed more efficiently by performing washing with an organic solvent after the removal of basic components contained in the polyarylene sulfide, so it is preferable to include a washing step with an organic solvent after the washing step with a solution of pH 8 or less.

[0072] In the post-treatment step, a hot water treatment can be further carried out, and it is also preferable to use this in combination with washing with the above-mentioned solution having a pH of 8 or less. When carrying out the hot water treatment, the following is the procedure. When treating the polyarylene sulfide with hot water, 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. A temperature below 100°C is not preferable because the desired chemical modification effect of the polyarylene sulfide is small.

[0073] In order to achieve the desired chemical modification effect of the polyarylene sulfide by the hot water treatment, it is preferable that the water used be distilled water or deionized water. There are no particular limitations on the procedure for the hot water treatment. It can be carried out by adding a predetermined amount of polyarylene sulfide to a predetermined amount of water, heating and stirring in a pressure vessel, or by continuous hot water treatment. The ratio of PPS resin to water is preferably higher, but a bath ratio (weight of cleaning solution relative to weight of dry polyarylene sulfide) of 200 g or less of polyarylene sulfide per liter of water is usually selected.

[0074] In addition, in order to avoid undesirable decomposition of the reactive functional groups at the terminals, it is desirable to carry out the treatment in an inert atmosphere. Furthermore, in order to remove remaining components, it is preferable to wash the polyarylene sulfide after this hot water treatment operation with warm water several times.

[0075] [Thermal oxidation crosslinking treatment] In addition, the polyarylene sulfide of the present invention can be used after being increased in molecular weight by a thermal oxidation crosslinking treatment, such as heating in an oxygen atmosphere after polymerization or heating with a crosslinking agent such as a peroxide added thereto. However, as will be described in detail later, the number average molecular weight is preferably 50,000 or less.

[0076] [Polyarylene sulfide of the present invention] The polyarylene sulfide obtained by the production method of the present invention can be used as a raw material for resin compositions, polymer modification, copolymerization, etc.; the preferred molecular weight varies depending on the application and cannot be generally defined; however, the number-average molecular weight is preferably 1,000 or more, more preferably 2,000 or more. A number-average molecular weight of 1,000 or more is preferable because sufficient chemical resistance can be obtained. Furthermore, the upper limit of the number-average molecular weight of the polyarylene sulfide is preferably 50,000 or less, more preferably 30,000 or less, and even more preferably 20,000 or less. A number-average molecular weight of 50,000 or less of the polyarylene sulfide is preferable because the melt viscosity is not too high and molding processability tends to be easy. The number-average molecular weight Mn is a value calculated in terms of polystyrene using gel permeation chromatography (GPC), a type of size exclusion chromatography (SEC).

[0077] The polyarylene sulfide obtained by the production method of the present invention preferably has 400 μmol / g or more of amino groups, more preferably 500 μmol / g or more, and even more preferably 700 μmol / g or more. Having the reactive functional groups at or above the above lower limit is preferable because the glass transition temperature of the polyarylene sulfide copolymer tends to be sufficiently high when producing the polyarylene sulfide copolymer described below. Furthermore, the upper limit of the amino group amount 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. Having the amino group amount at or below the above upper limit is preferable because it prevents a decrease in the chemical resistance of the polyarylene sulfide copolymer when producing the polyarylene sulfide copolymer described below.

[0078] The amino group in polyarylene sulfide can be determined by FT-IR analysis of the polyarylene sulfide, for example, by the 1900m -1 Amino group-derived absorption near 3360cm -1 The amount can be quantified by comparing the intensity of the absorption of

[0079] The halogen content of the polyarylene sulfide obtained by the production method of the present invention is preferably 8,000 ppm or less, more preferably 5,000 ppm or less, and even more preferably 3,000 ppm or less. When a polyarylene sulfide copolymer described below is produced using a polyarylene sulfide having a halogen content within the above range, a high molecular weight product can be easily obtained, which is preferable. Although the reason is unclear, it is thought that a low halogen content at the polymer terminals increases the proportion of amino groups at the terminals, making the copolymerization reaction more likely to occur. There is no lower limit to the halogen content of polyarylene sulfide, but examples include 500 ppm or more. The halogen content in polyarylene sulfide can be measured, for example, using a device combining a combustion device and ion chromatography. The halogen content of polyarylene sulfide originates from the dihalogenated aromatic compound used as the raw material and can be adjusted by increasing or decreasing the value of the [monomer ratio] described in the section on dihalogenated aromatic compounds above.

[0080] The polyarylene sulfide obtained by the production method of the present invention preferably has a weight loss rate of 5 wt% or less, more preferably 4 wt% or less, and even more preferably 3 wt% or less when heated from 30°C to 320°C at a temperature increase rate of 10°C / min. The smaller the weight loss rate, the better, and an example of this is 0.01 wt% or more. In the production method of the present invention, even if a large amount of amino groups are introduced into the polyarylene sulfide, unreacted monomers that easily become gas components when heated tend not to remain. Therefore, the weight loss rate can be reduced to 5 wt% or less.

[0081] The weight loss rate can be determined by general thermogravimetric analysis. A non-oxidizing atmosphere at normal pressure is typically used for this analysis. A non-oxidizing atmosphere is one in which the oxygen concentration in the gas phase in contact with the sample is 5% by volume or less, preferably 2% by volume or less, and more preferably substantially oxygen-free. It is preferable to use 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, normal pressure refers to atmospheric pressure, i.e., a pressure condition of approximately 101.3 kPa absolute pressure.

[0082] In addition, to measure the weight loss rate, thermogravimetric analysis is performed by raising the temperature from room temperature to any temperature above 320°C at a rate of 10°C / min. This temperature range is the temperature range frequently used for practical use of polyarylene sulfides, such as polyphenylene sulfide, or for melt molding and reaction. The weight loss rate in this practical use temperature range is an indicator of the amount of gas generated from polyarylene sulfide during practical use and the degree of contamination of equipment during molding, processing, and reactions. Therefore, polyarylene sulfides with low weight loss rates in this temperature range can be said to be high-quality, excellent polyarylene sulfides.

[0083] [Method for producing polyarylene sulfide copolymer] A polyarylene sulfide copolymer can also be produced by obtaining a polyarylene sulfide containing an amino group by the production method of the present invention, mixing it with at least one compound (B) (hereinafter sometimes abbreviated as compound (B)) selected from the following formulae (a) to (u), and heating the mixture:

[0084] [ka]

[0085] TIFF0007800209000007.tif76164

[0086] Here, X is any one selected from a carboxyl group, a silanol group, a sulfonic acid group, an acid anhydride group, an isocyanate group, an aldehyde group, an epoxy group, and an alkoxysilane group, and from the viewpoint of reactivity with polyarylene sulfide, an acid anhydride group is preferred. The aromatic ring of each compound represented by formulas (a) to (u) may be di- or tri-substituted, and the multiple substituents X substituted on one aromatic ring may be the same or different. R, R 1 , and R 2 is a substituent selected from hydrogen, an alkyl group having 1 to 12 carbon atoms, an aryl group having 6 to 24 carbon atoms, and a halogen group; R, R 1 , and R 2 may be the same or different, and are preferably hydrogen, a methyl group, an ethyl group, or a propyl group because of their availability.

[0087] Specific examples of the 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, 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)phthalic anhydride Examples of suitable benzophenones include benzophenone dianhydride, naphthalene-1,4,5,8-tetracarboxylic dianhydride, 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, and 4,4'-dicarboxylbiphenyl. Among these, 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'-dicarboxylbiphenylpyromellitic acid, and pyromellitic anhydride are preferably used.

[0088] The lower limit of the amount of compound (B) added is preferably 0.5 mol% or more, more preferably 1 mol% or more, and even more preferably 2 mol% or more, based on the sulfur atoms in the polyarylene sulfide. The upper limit is preferably 30 mol% or less, more preferably 20 mol% or less, and even more preferably 15 mol% or less, based on the sulfur atoms in the polyarylene sulfide. By adding an amount equal to or greater than the above lower limit, the decrease in rigidity of the resulting polyarylene sulfide copolymer at high temperatures can be sufficiently suppressed. Furthermore, as the amount of compound (B) added increases, the chemical resistance of the resulting polyarylene sulfide copolymer tends to decrease. However, by setting the amount of compound (B) added within the above range, a polyarylene sulfide copolymer exhibiting sufficient mechanical properties and chemical resistance can be easily produced. Here, the heating temperature is selected to be 200°C or higher, preferably 230°C or higher, and more preferably 250°C or higher. 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. A heating temperature of 200°C or higher can easily promote the reaction between the polyarylene sulfide and compound (B), and a temperature higher than the temperature at which the polyarylene sulfide melts can complete the reaction in a shorter time, which is preferable. The temperature at which the polyarylene sulfide melts varies depending on the composition and molecular weight of the polyarylene sulfide and the heating environment, and therefore cannot be uniquely determined. However, the melting temperature can be determined, for example, by analyzing the polyarylene sulfide with a differential scanning calorimeter. However, if the temperature is too high, undesirable side reactions, such as crosslinking reactions and decomposition reactions between polyarylene sulfides, tend to occur, which may result in deterioration of the properties of the resulting polyarylene sulfide copolymer. Therefore, it is desirable to avoid temperatures at which such undesirable side reactions occur significantly. The heating time varies depending on the composition and molecular weight of the polyarylene sulfide and the heating environment, and therefore cannot be uniquely determined. However, it is preferable to set the heating time so as to minimize the occurrence of the undesirable side reactions described above. The heating time can be, for example, 0.01 to 100 hours, preferably 0.1 to 20 hours, and more preferably 0.1 to 10 hours.If the reaction time is less than 0.01 hours, the reaction between the polyarylene sulfide and the compound (B) is likely to be insufficient, whereas if the reaction time exceeds 100 hours, not only will there be a tendency for undesirable side reactions to have a significant adverse effect on the properties of the resulting polyarylene sulfide copolymer, but there may also be economic disadvantages.

[0089] In the method for producing the polyarylene sulfide copolymer of the present invention, it is preferable to form an imide group by reacting an amino group of the polyarylene sulfide with X of the compound (B). The combination that forms the imide group is not particularly limited as long as it forms an imide group, but X of the compound (B) is preferably an acid anhydride group or a carboxyl group, and particularly preferably an acid anhydride group.

[0090] In the method for producing the polyarylene sulfide copolymer of the present invention, the heating can be carried out either in the absence of a solvent or in the presence of a solvent. However, from the viewpoint of preventing contamination of the molded product by gas generated during molding, it is preferable to carry out the heating in the absence of a solvent. When the heating is carried out in the presence of a solvent, the solvent is not particularly limited as long as it does not substantially cause undesirable side reactions such as decomposition or crosslinking of the produced polyarylene sulfide copolymer. The solvent can be used alone or as a mixture of two or more kinds.

[0091] Heating in the method for producing the polyarylene sulfide copolymer of the present invention can be carried out not only by a method using a conventional polymerization reaction apparatus, but also in a mold for producing a molded product, or by using an extruder or a melt kneader, and can be carried out without any particular limitation as long as it is an apparatus equipped with a heating mechanism, and known methods such as a batch method and a continuous method can be adopted.

[0092] In the method for producing a polyarylene sulfide copolymer of the present invention, heating is preferably performed in a non-oxidizing atmosphere, and also preferably under reduced pressure. When performing heating under reduced pressure, it is preferable to first convert the atmosphere in the reaction system to a non-oxidizing atmosphere and then to a reduced pressure. This tends to suppress the occurrence of undesirable side reactions, such as crosslinking reactions and decomposition reactions between polyarylene sulfides. 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 substantially oxygen-free, i.e., an inert gas atmosphere such as nitrogen, helium, or argon. Among these, a nitrogen atmosphere is particularly preferred from the standpoints of economy and ease of handling. A reduced pressure condition refers to a pressure lower than atmospheric pressure in the reaction system, with an upper limit of 50 kPa or less, more preferably 20 kPa or less, and even more preferably 10 kPa or less. An example of a lower limit is 0.1 kPa or more. When the pressure is below the preferred upper limit, undesirable side reactions such as crosslinking reactions tend to be suppressed, while when the pressure is above the preferred lower limit, unnecessary pressure load on the reaction apparatus is not applied, which is preferred.

[0093] The glass transition point of the polyarylene sulfide copolymer obtained by the production method of the present invention is preferably 95°C or higher, more preferably 100°C or higher, and even more preferably 110°C or higher. A glass transition point of 95°C or higher is preferable because high rigidity can be obtained under high-temperature conditions. Furthermore, the glass transition point of the polyarylene sulfide copolymer is preferably 190°C or lower, more preferably 180°C or lower, and even more preferably 160°C or lower. A glass transition point of 190°C or lower is preferable because the chemical resistance of the molded article is maintained. Here, the glass transition point 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. Furthermore, the polyarylene sulfide copolymer obtained by the production method of the present invention preferably has a melting point of 300°C or lower, or does not have a melting point at all. A melting point of 300°C or lower or no melting point facilitates melt molding. Here, the melting point is the melting peak temperature detected when a differential scanning calorimeter is used to raise the temperature from 0°C to 340°C at a rate of 20°C / min, hold at 340°C for 1 minute, lower the temperature to 100°C at a rate of 20°C / min, hold at 100°C for 1 minute, and then raise the temperature again to 340°C at a rate of 20°C / min. "Having no melting point" is defined as no clear melting peak being observed when measurement is performed using a differential scanning calorimeter under the above conditions. The melting point can be adjusted by selecting the molecular weight of the arylene sulfide unit in the polyarylene sulfide copolymer.

[0094] The polyarylene sulfide copolymer obtained by the production method of the present invention preferably has a weight-average molecular weight of 40,000 or more, preferably 45,000 or more, more preferably 50,000 or more, even more preferably 70,000 or more, and even more preferably 100,000 or more. A weight-average molecular weight of 10,000 or more is preferred because the toughness and mechanical strength of the polyarylene sulfide copolymer tend to be sufficiently high. There is no particular upper limit to the weight-average molecular weight, but a preferred range is less than 1,000,000, more preferably less than 500,000, and even more preferably less than 200,000. This range is preferred because it provides excellent moldability.

[0095] The weight average molecular weight can be determined, for example, by using SEC (size exclusion chromatography) equipped with a differential refractive index detector.

[0096] The polyarylene sulfide and polyarylene sulfide copolymer obtained by the production method of the present invention can be blended with a filler and other additives to be used as a polyarylene sulfide resin composition. The blending method in producing the resin composition is not particularly limited, but a representative example includes a method in which the mixture is fed into a known melt kneader such as a single-screw or twin-screw extruder, a Banbury mixer, a kneader, or a mixing roll, and kneaded at a processing temperature that is 5 to 100°C above the melting peak temperature of the polyarylene sulfide copolymer.

[0097] For example, the filler may be an inorganic filler or an organic filler.

[0098] The type of filler is not limited, 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, when the filler is carbon fiber, the effect of improving the mechanical properties and chemical resistance of the resin composition is more pronounced, making it more preferred.

[0099] The polyarylene sulfide and polyarylene sulfide copolymer obtained by the present invention are excellent in heat resistance, chemical resistance, flame retardancy, electrical properties and mechanical properties, and can be molded not only into injection molding, injection compression molding and blow molding applications, but also into extrusion molding products such as sheets, films, fibers and pipes.

[0100] Furthermore, examples of applications of resin compositions using polyarylene sulfide and polyarylene sulfide copolymers obtained by the present invention include electric 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, aerospace-related parts, and various other applications. [Example]

[0101] 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.

[0102] [Analysis of functional group content] The amount of amino acid introduced into polyarylene sulfide was measured by FT-IR (IR-810 infrared spectrophotometer manufactured by JASCO Corporation) of an amorphous film of polyarylene sulfide prepared by quenching from a molten state, and the amount of amino acid introduced into polyarylene sulfide was measured by FT-IR (IR-810 infrared spectrophotometer manufactured by JASCO Corporation) of the 1900 cm -1 The absorption at around 3360 cm originates from the amino group. -1 was estimated by comparing the absorption of

[0103] [Molecular weight measurement] The number average molecular weight Mn of polyarylene sulfide and the weight average molecular weight Mw of polyarylene sulfide copolymer were calculated in terms of polystyrene by 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.

[0104] [Measurement of weight loss rate upon heating] The weight loss rate of the polyarylene sulfide upon heating was measured using a thermogravimetric analyzer under the following conditions. Apparatus: PerkinElmer TGA7 Measurement atmosphere: Nitrogen flow Sample weight: approx. 5 mg Measurement conditions (a) Program temperature 30℃, hold for 1 minute (b) The program temperature was increased from 30°C to 340°C at a rate of 10°C / min. The weight loss rate was calculated from the weight measured under the above conditions at 320°C and the weight measured at 30°C using the following formula. Weight loss rate (%) = ((weight (mg) at 30°C - weight (mg) at 320°C) / weight (mg) at 30°C) × 100.

[0105] [Analysis of halogen content in polymers] Using a Dia Instruments AQF-100 automatic sample combustion apparatus, 1-20 mg of polymer was combusted at a final temperature of 1000°C, and the generated gas components were absorbed in 10 mL of water containing a dilute oxidant. The absorbed solution was then subjected to a DIONEX ICS1500 ion chromatography system using a sodium carbonate / sodium bicarbonate mixed aqueous solution as the mobile phase to measure the amount of halogen in the polymer. Note that the halogen atoms detected and quantified here refer to fluorine, chlorine, bromine, and iodine in the polymer.

[0106] [Reference example 1] A 70-liter autoclave equipped with a stirrer and a bottom stop valve was charged with 7.14 kg (61.6 mol) of 48.4% sodium hydrosulfide, 2.87 kg (69.3 mol) of 97% sodium hydroxide, 14.57 kg (147 mol) of N-methyl-2-pyrrolidone (NMP), and 4.19 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 7.88 kg of water and 0.039 kg of NMP had distilled out. At this point, the amount of hydrogen sulfide released was 1.4 mol, so the amount of inorganic sulfidizing agent in the system after this step was 60.2 mol.

[0107] The mixture was then cooled to 200°C, and 9.45 kg (64.3 mol) of p-dichlorobenzene (p-DCB), 1.02 kg (8.23 mol) of 4-aminothiophenol (4-ATP), and 2.78 kg (28.0 mol) of NMP were added. The reaction vessel was then sealed under nitrogen gas, and the temperature was raised to 260°C at a rate of 0.6°C / min while stirring at 240 rpm, and the reaction was carried out at 260°C for 120 minutes.

[0108] Immediately after the reaction was completed, the bottom plug valve of the autoclave was opened, and the contents were flushed into an apparatus equipped with a stirrer, which was then dried and solidified for 1.5 hours at 230°C in the apparatus equipped with a stirrer, and a solid containing PPS and salts was recovered.

[0109] The recovered material and ion-exchanged water were placed in an autoclave equipped with a stirrer, washed at 75°C for 15 minutes, and then filtered three times to obtain a cake.

[0110] [Example 1] The cake obtained in Reference Example 1, acetic acid, and 30 L of ion-exchanged water were placed in an autoclave equipped with a stirrer, and the pH of the solution was adjusted to 4. The atmosphere inside the autoclave was replaced with nitrogen and then heated to 195°C. The autoclave was then cooled, and the contents were filtered through a filter to obtain a cake. The resulting cake was washed with 30 L of ion-exchanged water for 15 minutes and filtered three times, and then dried at 120°C under a nitrogen stream. 3 kg of the resulting PPS and 30 kg of N-methyl-2-pyrrolidone (NMP) were placed in a container equipped with a stirrer, stirred at 50 rpm for 30 minutes, and then filtered to obtain a cake. The resulting cake was washed with 30 L of ion-exchanged water for 15 minutes and filtered three times, and then dried at 120°C under a nitrogen stream for 4 hours to obtain a dried PPS. The dried PPS had an amino group content of 730 μmol / g, a chlorine content of 1000 ppm, a number average molecular weight of 1800, and a weight loss rate of 1 wt% upon heating. No halogens other than chlorine were detected.

[0111] [Example 2] The cake obtained in Reference Example 1, acetic acid, and 30 L of ion-exchanged water were placed in an autoclave equipped with a stirrer, and the pH of the solution was adjusted to 7. The atmosphere inside the autoclave was replaced with nitrogen and then heated to 195°C. The autoclave was then cooled, and the contents were filtered through a filter to obtain a cake. The resulting cake was washed with 30 L of ion-exchanged water for 15 minutes and filtered three times, and then dried at 120°C under a nitrogen stream. 3 kg of the resulting PPS and 30 kg of N-methyl-2-pyrrolidone (NMP) were placed in a container equipped with a stirrer, stirred at 50 rpm for 30 minutes, and then filtered to obtain a cake. The resulting cake was washed with 30 L of ion-exchanged water for 15 minutes and filtered three times, and then dried at 120°C under a nitrogen stream for 4 hours to obtain a dried PPS. The dried PPS had an amino group content of 730 μmol / g, a chlorine content of 1000 ppm, a number average molecular weight of 1800, and a weight loss rate of 1 wt% upon heating. No halogens other than chlorine were detected.

[0112] [Comparative Example 1] The cake obtained in Reference Example 1 and 30 L of ion-exchanged water were 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 filtered to obtain a cake. The resulting cake was dried at 120°C under a nitrogen stream. 3 kg of the resulting PPS and 30 kg of N-methyl-2-pyrrolidone (NMP) were placed in a container equipped with a stirrer and stirred at 50 rpm for 30 minutes. The mixture was then filtered to obtain a cake. The resulting cake was washed with 30 L of ion-exchanged water for 15 minutes and filtered three times. The resulting cake was then dried at 120°C for 4 hours under a nitrogen stream to obtain a dried PPS. The dried PPS had an amino group content of 730 μmol / g, a chlorine content of 1000 ppm, a number-average molecular weight of 1800, and a weight loss upon heating of 1 wt%. No halogens other than chlorine were detected.

[0113] As shown in Examples 1 and 2, the production method of the present invention can easily and efficiently provide a polyarylene sulfide that contains amino groups and generates a small amount of gas when heated.

[0114] [Examples 3 to 6, Comparative Examples 2 to 3] The PPS obtained in Examples 1 and 2 and Comparative Example 1 and Compound (B), a copolymerization component weighed so that the functional group content was equivalent to that of PPS, were placed in a reactor equipped with a stirring blade and capable of vacuuming and nitrogen replacement. The reactor was then vacuumed and purged with nitrogen three times. The reactor was filled with a nitrogen atmosphere and heated to 320°C for 20 or 60 minutes with stirring, then cooled to room temperature to obtain a polyarylene sulfide copolymer. FT-IR spectroscopy confirmed that the resulting polyarylene sulfide copolymer contained phenylene sulfide units as structural units and had imide groups derived from the copolymerization components. After the polyarylene sulfide copolymer was removed from the reactor, the degree of contamination of the reactor due to gas components evolved during heating was evaluated according to the following criteria. A: No need to clean before preparing the next batch B: Can be used for the next batch after cleaning with room temperature NMP C: For the next batch, NMP reflux at a temperature above the boiling point is required for cleaning. The weight average molecular weight Mw, glass transition temperature Tg, melting point Tm of the polyarylene sulfide copolymer, and the evaluation results of the contamination level of the reaction vessel are shown in Table 1.

[0115] [Table 1]

[0116] The abbreviations for each compound in the table refer to the following compounds. PDA: Pyromellitic anhydride A comparison of Example 3, Example 4, and Comparative Example 2 shows that a polyarylene sulfide copolymer with a higher molecular weight can be obtained by using a polyarylene sulfide obtained by the production method of the present invention, which includes a washing step with a solution of pH 8 or less in the post-treatment step. Furthermore, a comparison of Example 5, Example 6, and Comparative Example 3 shows that the effect of the production method of the present invention is more evident when the copolymerization time is extended, and a polyarylene sulfide copolymer with a higher molecular weight can be obtained. Furthermore, the production method of the present invention can suppress contamination of the reaction vessel when producing a polyarylene sulfide copolymer, making it possible to omit or simplify the step of washing the reaction vessel, thereby improving workability.

Claims

1. In a method for producing polyarylene sulfide, at least a dihalogenated aromatic compound, an inorganic sulfidizing agent, and compound (A) are reacted in an organic polar solvent in the presence of an alkali metal hydroxide, and the compound (A) is present in a reaction vessel in an amount of 0.04 mol or more and 0.5 mol or less per mol of the inorganic sulfidizing agent, and the compound (A) has at least one aromatic ring and, on the one aromatic ring, has an amino group and at least one functional group selected from a thiol group and a salt of a thiol group, and to a reaction vessel at the same stage as adding a dihalogenated aromatic compound to the reaction vessel, and a post-treatment step includes a washing step with a solution of pH 8 or less and a washing step with an organic solvent selected from N-methyl-2-pyrrolidone, dimethylformamide, and chloroform to obtain polyarylene sulfide, and then mixing with at least one compound (B) selected from the following formulae (a) to (u), followed by heating: 【Chemistry 1】 (wherein X is any one selected from a carboxyl group, a silanol group, a sulfonic acid group, an acid anhydride group, an isocyanate group, an aldehyde group, an epoxy group, and an alkoxysilane group; R, R 1 , and R 2 are substituents selected from hydrogen, an alkyl group having 1 to 12 carbon atoms, an aryl group having 6 to 24 carbon atoms, and a halogen group; and R, R 1 , and R 2 may be the same or different.)

2. 2. The method for producing the polyarylene sulfide copolymer according to claim 1, further comprising a step of washing with an organic solvent after the step of washing with the solution having a pH of 8 or less.

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