Polyphenylene sulfide resin composition and molded article

Abstract

To provide a polyphenylene sulfide resin composition which can suppress oxidative crosslinking in an environment exceeding 200 °C and is excellent in long-term high-temperature durability of mechanical properties.SOLUTION: In an absorbance spectrum obtained by infrared spectroscopy (transmission method) using an amorphous film (x) of the polyphenylene sulfide composition and an amorphous film (y) obtained after heat treatment of the film at 220 °C for 500 hours in the atmosphere, when maximum peak intensities present in a wave number range of 1210 to 1245cm - 1 are (X) and (Y), respectively, the following formula (A) is satisfied: (Y) - (X) <0.5 Formula (A) SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a polyphenylene sulfide resin composition that can suppress oxidative crosslinking in an environment exceeding 200°C and has excellent long-term high-temperature durability of mechanical properties. [Background technology]

[0002] Polyphenylene sulfide (hereinafter sometimes abbreviated as PPS) resin has a good balance of properties such as heat resistance, chemical resistance, and flame retardancy, making it suitable for use in a variety of applications, including automobiles, housing equipment, and electrical and electronic equipment. However, PPS resin also suffers from the problem of undergoing oxidative crosslinking and becoming brittle and deteriorating in long-term high-temperature environments above 150°C. This means that, for example, in automotive and electrical and electronic applications, PPS resin cannot withstand the rising environmental temperatures associated with higher power output and space savings, limiting its range of applications.

[0003] Several attempts to improve the durability and stability of PPS resin at high temperatures have been reported. Patent Document 1 discloses a PPS resin composition that is able to maintain high tensile elongation at break in a long-term environment at 200°C by blending an organosilane compound and a phosphorus oxoacid metal salt into the PPS resin. Patent Document 2 also discloses a PPS resin composition that is able to maintain high thermal stability and mechanical properties when the PPS resin is heated to or above its melting point and melt-processed by blending a specific transition metal compound and an amine compound into the PPS resin. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2018 / 151191 [Patent Document 2] International Publication No. 2021 / 054251 Summary of the Invention [Problem to be solved by the invention]

[0005] The environmental temperatures in applications where PPS resin has been used are becoming increasingly higher. For example, in electric vehicles, where development is gaining momentum due to growing environmental awareness, the increased power output of motors is causing the heat generation temperature of electric wires to rise from below 200°C to above 200°C. Accordingly, the insulation materials for electric wires are required to have long-term durability in even higher temperature environments. In other words, there is a need for technology that can suppress the oxidative crosslinking of PPS resin in environments exceeding 200°C.

[0006] However, the present inventors have found that the PPS resin composition described in Patent Document 1 does not sufficiently suppress oxidative crosslinking in an environment above 200°C. Similarly, the present inventors have found that the PPS resin composition described in Patent Document 2 does not sufficiently suppress oxidative crosslinking at 220°C. It was inferred that Patent Document 2 is effective in improving thermal stability for a relatively short period (approximately 30 minutes or less) when the PPS resin is heated to or above its melting point and melt-processed, but is not effective when the PPS resin is left in an environment below its melting point but above 200°C for a relatively long period (approximately 1 hour or more).

[0007] Therefore, an object of the present invention is to obtain a polyphenylene sulfide resin composition that suppresses oxidative crosslinking in an environment exceeding 200°C and has excellent long-term high-temperature durability of mechanical properties. [Means for solving the problem]

[0008] As a result of investigations conducted by the present inventors to solve the above problems, they have found that, by preparing a polyphenylene sulfide resin composition that satisfies the following formula (A), (a) oxidative crosslinking of the polyphenylene sulfide resin in an environment exceeding 200°C can be suppressed, and the polyphenylene sulfide resin composition has excellent long-term high-temperature durability in mechanical properties.

[0009] That is, the present invention has been made to solve at least part of the above-mentioned problems, and can be implemented in the following forms. (1) (a) A polyphenylene sulfide resin composition containing a polyphenylene sulfide resin, wherein an amorphous film (x) of the resin composition and an amorphous film (y) obtained by heat-treating the film at 220°C in the atmosphere for 500 hours are subjected to infrared spectroscopy (transmission method) to obtain an amorphous film (y) having a wave number of 1210 to 1245 cm. -1 When the maximum peak intensities present in the range are (X) and (Y), respectively, a polyphenylene sulfide resin composition that satisfies the following formula (A): (Y)-(X)<0.5 Equation (A) (2) The polyphenylene sulfide resin composition according to (1), further comprising (b) a metal salt. (3) The polyphenylene sulfide resin composition according to (2), wherein the (b) metal salt is (b1) a nickel salt. (4) The polyphenylene sulfide resin composition according to (2), wherein the (b) metal salt is (b2) an alkali metal salt, the ionic radius ratio of the constituting anion to the conjugate acid of the anion is 2.7 or more, and the pKa of the conjugate acid of the anion is −9.5 or less. (5) The polyphenylene sulfide resin composition according to (2), wherein the (b) metal salt is (b3) an alkaline earth metal salt, the ionic radius ratio of the constituting anion to the constituting cation is 1.7 or more, and the pKa of the conjugate acid of the anion is −9.5 or less. (6) The polyphenylene sulfide resin composition according to any one of (2) to (5), wherein the metal salt (b) is a compound containing iodine. (7) (a) The polyphenylene sulfide resin composition according to any one of (1) to (6), wherein the polyphenylene sulfide resin has a temperature-lowering crystallization peak temperature of 200°C or less as determined by differential scanning calorimetry. (8) (a) The polyphenylene sulfide resin composition according to any one of (1) to (7), wherein the polyphenylene sulfide resin has a weight-average molecular weight of 75,000 or more. (9) The polyphenylene sulfide resin composition according to any one of (1) to (8), wherein the tensile strength retention is measured using an ASTM No. 4 dumbbell obtained by injection molding the polyphenylene sulfide resin composition under conditions of a tensile speed of 10 mm / min, a gripping distance of 64 mm, and an ambient temperature of 23°C, and calculated by the following formula (B) is 100% or more. (Tensile strength after heat treatment at 220°C for 250 hours in air) / (Tensile strength before heat treatment) × 100 Formula (B) (10) A molded article made of the polyphenylene sulfide resin composition according to any one of (1) to (9). (11) A covering member for an electric wire, comprising the polyphenylene sulfide resin composition according to any one of (1) to (9). (12) The covering member for an electric wire according to (11), which has a heat generation temperature exceeding 200°C. (13) A plastic fastener made of the polyphenylene sulfide resin composition according to any one of (1) to (9). [Effects of the Invention]

[0010] According to the present invention, a PPS resin composition can be obtained that can suppress oxidative crosslinking in environments exceeding 200°C and has excellent long-term high-temperature durability in mechanical properties. Furthermore, due to these properties, even when the PPS resin composition of the present invention is applied to a covering material for an electric wire that generates heat at temperatures exceeding 200°C, it is possible to prevent a decrease in insulation properties due to cracking. Furthermore, when the PPS resin composition of the present invention is applied to a plastic fastener, which is a component that is used over a long period of time and is subjected to external forces, it is possible to maintain its shape in a long-term high-temperature environment. DETAILED DESCRIPTION OF THE INVENTION

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

[0012] (1)(a) Polyphenylene sulfide resin The polyphenylene sulfide resin (a) used in the present invention is a polymer having a repeating unit represented by the following structural formula:

[0013] [ka]

[0014] From the viewpoint of heat resistance, a polymer containing 70 mol % or more, and even more preferably 90 mol % or more, of a polymer containing a repeating unit represented by the above structural formula is preferred. Furthermore, (a) PPS resin may be composed of a repeating unit having the following structure, etc., at about less than 30 mol % of its repeating units.

[0015] [ka]

[0016] A PPS copolymer partially having such a structure has a melting point lower than the general melting point of PPS, 280° C., and therefore such a resin composition is advantageous in terms of moldability.

[0017] The weight-average molecular weight of the (a) PPS resin used in the present invention is preferably 30,000 to 150,000, more preferably 40,000 to 130,000, 45,000 to 110,000, or 50,000 to 90,000, particularly preferably 70,000 to 90,000, and even more preferably 75,000 to 90,000. A low weight-average molecular weight leads to poor mechanical properties of the (a) PPS resin itself, poor mechanical properties of the PPS resin composition, and increased susceptibility to cracking when applied to electrical wire coatings or plastic fasteners. Therefore, a weight-average molecular weight of 30,000 or more is preferred. On the other hand, a weight-average molecular weight exceeding 150,000 tends to result in significantly increased melt viscosity, which is undesirable for molding. In the present invention, a mixture of (a) PPS resins with different weight-average molecular weights may be used.

[0018] The weight average molecular weight in the present invention is a value calculated in terms of polystyrene using a gel permeation chromatography (GPC) manufactured by Senshu Scientific Co., Ltd.

[0019] The (a) PPS resin used in the present invention preferably has a cooling-down crystallization peak temperature of 200°C or less, as determined by differential scanning calorimetry (DSC). The cooling-down crystallization peak temperature is more preferably 195°C or less, and particularly preferably 190°C or less. There is no particular lower limit, but a substantial lower limit of 100°C or more can be exemplified. An (a) PPS resin having a cooling-down crystallization peak temperature of 200°C or less can be obtained, for example, by treating it with an alkali metal or alkaline earth metal in the post-treatment step described below. The (a) PPS resin obtained by treatment with an alkali metal or alkaline earth metal is preferred because it improves the stability of the (a) PPS resin terminals during the heat treatment process, thereby suppressing oxidative crosslinking of the (a) PPS resin in long-term high-temperature environments exceeding 200°C, resulting in a PPS resin composition with excellent long-term high-temperature durability of mechanical properties.

[0020] The cooling crystallization peak temperature of (a) PPS resin is obtained by measurement under the following conditions in a nitrogen atmosphere using a differential scanning calorimeter (DSC, Q200; manufactured by TA Instruments): (a) PPS resin is heated from 50°C to 340°C at a rate of 20°C / min. It is then held at 340°C for 1 minute and cooled to 100°C at a rate of 20°C / min. The cooling crystallization peak temperature (Tmc) is obtained from the value of the cooling crystallization peak top detected during the cooling process.

[0021] A method for producing the (a) PPS resin used in the present invention will be described below, but the method is not limited to the following method as long as the (a) PPS resin having the above-mentioned properties can be obtained.

[0022] First, the polyhalogenated aromatic compound, sulfidizing agent, polymerization solvent, molecular weight regulator, polymerization aid and polymerization stabilizer used in the production method will be described.

[0023] [Polyhalogenated aromatic compounds] The polyhalogenated aromatic compound refers to a compound having two or more halogen atoms in one molecule. Specific examples include polyhalogenated aromatic compounds such as p-dichlorobenzene, m-dichlorobenzene, o-dichlorobenzene, 1,3,5-trichlorobenzene, 1,2,4-trichlorobenzene, 1,2,4,5-tetrachlorobenzene, hexachlorobenzene, 2,5-dichlorotoluene, 2,5-dichloro-p-xylene, 1,4-dibromobenzene, 1,4-diiodobenzene, and 1-methoxy-2,5-dichlorobenzene, and preferably p-dichlorobenzene. In addition, for the purpose of introducing carboxyl groups, one preferred embodiment is to use a carboxyl group-containing dihalogenated aromatic compound such as 2,4-dichlorobenzoic acid, 2,5-dichlorobenzoic acid, 2,6-dichlorobenzoic acid, or 3,5-dichlorobenzoic acid, or a mixture thereof, as a copolymerization monomer. Although it is also possible to combine two or more different polyhalogenated aromatic compounds to form a copolymer, it is preferable to use a p-dihalogenated aromatic compound as the main component.

[0024] The amount of the polyhalogenated aromatic compound used is, for example, in the range of 0.9 to 2.0 mol, preferably 0.95 to 1.5 mol, and more preferably 1.005 to 1.2 mol per mol of the sulfidizing agent, in order to obtain (a) PPS resin with a viscosity suitable for processing.

[0025] [Sulfidizing agent] The sulfidizing agent includes alkali metal sulfides, alkali metal hydrosulfides, and hydrogen sulfide.

[0026] 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, with sodium sulfide being preferred. These alkali metal sulfides can be used as hydrates, aqueous mixtures, or anhydrous forms.

[0027] Specific examples of alkali metal hydrosulfides include sodium hydrosulfide, potassium hydrosulfide, lithium hydrosulfide, rubidium hydrosulfide, cesium hydrosulfide, and mixtures of two or more of these, with sodium hydrosulfide being preferred. These alkali metal hydrosulfides can be used as hydrates, aqueous mixtures, or anhydrous forms.

[0028] Alternatively, an alkali metal sulfide prepared in situ in the reaction system from an alkali metal hydrosulfide and an alkali metal hydroxide can be used.Also, an alkali metal sulfide can be prepared from an alkali metal hydrosulfide and an alkali metal hydroxide and then transferred to a polymerization vessel for use.

[0029] Alternatively, an alkali metal sulfide prepared in situ in the reaction system from an alkali metal hydroxide such as lithium hydroxide or sodium hydroxide and hydrogen sulfide can be used.Also, an alkali metal sulfide can be prepared from an alkali metal hydroxide such as lithium hydroxide or sodium hydroxide and hydrogen sulfide, and then transferred to a polymerization vessel for use.

[0030] When a part of the sulfidizing agent is lost before the start of the polymerization reaction due to a dehydration operation or the like, the amount of the charged sulfidizing agent means the remaining amount obtained by subtracting the lost amount from the actual charged amount.

[0031] It is also possible to use an alkali metal hydroxide and / or alkaline earth metal hydroxide together with the sulfidizing agent. Specific examples of alkali metal hydroxides include sodium hydroxide, potassium hydroxide, lithium hydroxide, rubidium hydroxide, cesium hydroxide, and mixtures of two or more of these. Specific examples of alkaline earth metal hydroxides include calcium hydroxide, strontium hydroxide, barium hydroxide, etc., and sodium hydroxide is preferably used among them.

[0032] When an alkali metal hydrosulfide is used as the sulfidizing agent, it is particularly preferable to use an alkali metal hydroxide simultaneously. The amount used is, for example, in the range of 0.95 to 1.20 mol, preferably 1.00 to 1.15 mol, and more preferably 1.005 to 1.100 mol per mol of the alkali metal hydrosulfide.

[0033] [Polymerization solvent] As the polymerization solvent, an organic polar solvent is preferably used. Specific examples include N-alkylpyrrolidones such as N-methyl-2-pyrrolidone and N-ethyl-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, hexamethylphosphoric triamide, dimethyl sulfone, and tetramethylene sulfoxide, and mixtures thereof. These solvents are preferably used because of their high reaction stability. Among these, N-methyl-2-pyrrolidone (hereinafter sometimes abbreviated as NMP) is particularly preferred.

[0034] The amount of the organic polar solvent used is selected from the range of 2.0 to 10 moles, preferably 2.25 to 6.0 moles, more preferably 2.5 to 5.5 moles per mole of the sulfidizing agent.

[0035] [Molecular weight regulator] A monohalogen compound (which does not necessarily have to be an aromatic compound) can be used in combination with the polyhalogenated aromatic compound in order to form terminals of the resulting (a) PPS resin or to adjust the polymerization reaction or molecular weight.

[0036] [Polymerization aid] In one preferred embodiment, a polymerization aid is used to obtain a (a) PPS resin 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 (a) PPS resin. 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 the organic carboxylates and lithium chloride being preferred as the alkali metal chlorides.

[0037] 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.

[0038] The alkali metal carboxylate may be formed 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, while potassium, rubidium, and cesium salts are thought to have insufficient solubility in the reaction system. Therefore, sodium acetate, which is inexpensive and has moderate solubility in the polymerization system, is most preferably used.

[0039] 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 alkali metal sulfide, and in terms of obtaining a higher degree of polymerization, the amount used is preferably in the range of 0.1 mol to 0.6 mol, and more preferably in the range of 0.2 mol to 0.5 mol.

[0040] 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 alkali metal sulfide, and in order to obtain a higher degree of polymerization, the amount is preferably in the range of 0.6 mol to 10 mol, and more preferably in the range of 1 mol to 5 mol.

[0041] 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 a smaller amount of each.

[0042] 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, as described below, or may be added in several divided portions, but when an alkali metal carboxylate is used as the polymerization aid, 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 of addition. Also, when water is used as the polymerization aid, it is effective to add it during the polymerization reaction after charging the polyhalogenated aromatic compound.

[0043] [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 production of thiophenol, and the addition of a polymerization stabilizer can suppress this production. 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. Furthermore, when using an alkali metal hydrosulfide as a sulfidizing agent, it is particularly preferable to use an alkali metal hydroxide simultaneously. However, an excess amount of alkali metal hydroxide relative to the sulfidizing agent can also function as a polymerization stabilizer.

[0044] 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 to 0.2 mol, preferably 0.03 to 0.1 mol, more preferably 0.04 to 0.09 mol per mol of the charged alkali metal sulfide. If this proportion is too small, the stabilizing effect is insufficient, while if it is too large, it tends to be economically disadvantageous and the polymer yield tends to decrease.

[0045] The timing of adding the polymerization stabilizer is not particularly specified, and it may be added at any time during the pre-step described below, at the start of polymerization, or during polymerization, 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.

[0046] Next, a preferred method for producing the (a) PPS resin used in the present invention will be specifically explained in order, including a pre-process, a polymerization reaction process, a recovery process, and a post-treatment process, but the method is not limited to this method.

[0047] [Pre-process] (a) In the production method of PPS resin, the sulfidizing agent is usually used in the form of a hydrate. However, it is preferable to heat the mixture containing the organic polar solvent and the sulfidizing agent and remove excess water from the system before adding the polyhalogenated aromatic compound.

[0048] As mentioned above, sulfidizing agents prepared in situ in the reaction system or in a separate vessel from the polymerization vessel can also be used. 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 to 260°C, under atmospheric or reduced pressure, to distill off water. A polymerization aid may also be added at this stage. To promote the distillation of water, the reaction may be carried out with the addition of toluene or the like.

[0049] In the polymerization reaction, the amount of water in the polymerization system is preferably 0.3 to 10.0 moles per mole of the charged sulfidizing agent. Here, the amount of water in the polymerization system is the amount of water charged to the polymerization system minus the amount of water removed from the polymerization system. The charged water may be in any form, such as water, an aqueous solution, or water of crystallization.

[0050] [Polymerization reaction process] (a) PPS resin is produced by reacting a sulfidizing agent with a polyhalogenated aromatic compound in an organic polar solvent at a temperature range of 200°C or higher but lower than 290°C.

[0051] When starting the polymerization reaction process, the organic polar solvent, sulfidizing agent, and polyhalogenated aromatic compound are mixed together, preferably in an inert gas atmosphere, at a temperature ranging from room temperature to 240°C, and preferably from 100°C to 230°C. A polymerization aid may be added at this stage. These raw materials may be added in any order, or simultaneously.

[0052] 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-raising rate, but a rate of 0.01 to 5° C. / min is usually selected, and a range of 0.1 to 3° C. / min is more preferred.

[0053] In general, the temperature is finally raised to a temperature of 250 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.

[0054] 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.

[0055] In order to obtain a polymer with a higher degree of polymerization, it may be effective to carry out the polymerization in multiple stages. When carrying out the polymerization in multiple stages, it is effective to carry out the polymerization when the conversion rate of the polyhalogenated aromatic compound in the system at 245°C reaches 40 mol% or more, preferably 60 mol%.

[0056] The conversion rate of polyhalogenated aromatic compounds (abbreviated as PHA herein) is a value calculated by the following formula: The amount of remaining 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 = [amount of PHA charged (mol) - amount of remaining PHA (mol)] / [amount of PHA charged (mol) - amount of excess PHA (mol)]. (B) Cases other than (A) above Conversion rate = [amount of PHA charged (mol) - amount of remaining PHA (mol)] / [amount of PHA charged (mol)].

[0057] [Recovery process] In the (a) PPS resin production method, after polymerization is complete, solid matter is recovered from the polymerization reaction product containing the polymer, solvent, etc. A preferred recovery method involves slowly cooling the product after the polymerization reaction is complete to recover the particulate polymer. 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 the product at the same rate throughout the entire cooling process; instead, it is possible to use a method in which the product is cooled at a rate of 0.1 to 1°C / min until the polymer particles crystallize and precipitate, and then slowly cooled at a rate of 1°C / min or faster.

[0058] [Post-processing process] (a) The PPS resin 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.

[0059] The acid treatment is carried out as follows: There are no particular restrictions on the acid used in the acid treatment of the (a) PPS resin, so long as it does not have the effect of decomposing the (a) PPS resin, and examples thereof include acetic acid, hydrochloric acid, sulfuric acid, phosphoric acid, silicic acid, carbonic acid, and propylic acid, and among these, acetic acid and hydrochloric acid are more preferably used, but acids such as nitric acid that decompose and deteriorate the (a) PPS resin are not preferred.

[0060] The acid treatment may be carried out by immersing the (a) PPS resin in an acid or an aqueous solution of an acid, with stirring or heating as necessary. For example, when using acetic acid, a sufficient effect can be obtained by immersing the PPS resin powder in an aqueous solution of pH 4 heated to 80 to 200°C and stirring for 30 minutes. The pH after treatment may be 4 or higher, for example, about pH 4 to 8. The acid-treated (a) PPS resin is preferably washed several times with water or warm water to remove any remaining acid or salt. The water used for washing is preferably distilled water or deionized water, so as not to impair the desired chemical modification effect of the (a) PPS resin by the acid treatment.

[0061] The hot water treatment is carried out as follows: When treating the (a) PPS resin 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. A temperature below 100° C. is not preferred because the desired chemical modification effect of the (a) PPS resin is small.

[0062] To achieve the desired chemical modification effect of the (a) PPS resin by hot water washing, it is preferable to use distilled water or deionized water. There are no particular restrictions on the hot water treatment procedure, and it can be carried out by adding a predetermined amount of (a) PPS resin to a predetermined amount of water, heating and stirring in a pressure vessel, or by continuous hot water treatment. The ratio of (a) PPS resin to water is preferably higher, but a bath ratio of 200 g or less of (a) PPS resin to 1 liter of water is usually selected.

[0063] Furthermore, since decomposition of the terminal groups is undesirable, it is desirable to carry out the treatment in an inert atmosphere to avoid this.Furthermore, after this hot water treatment, the (a) PPS resin is preferably washed several times with warm water to remove any remaining components.

[0064] When washing with an organic solvent, the procedure is as follows: (a) The organic solvent used for washing the PPS resin is not particularly limited as long as it does not have the effect of decomposing the PPS resin, and examples thereof include nitrogen-containing polar solvents such as N-methyl-2-pyrrolidone, dimethylformamide, dimethylacetamide, 1,3-dimethylimidazolidinone, hexamethylphosphoramide, and piperazinones; sulfoxide-sulfone solvents such as dimethyl sulfoxide, dimethyl sulfone, and sulfolane; ketone solvents such as acetone, methyl ethyl ketone, diethyl ketone, and acetophenone; dimethyl ether, dipropyl ether, dioxane, and tetrahydrofuran; Examples of suitable organic solvents include ether solvents such as hydrofuran, halogenated solvents such as chloroform, methylene chloride, trichloroethylene, ethylene dichloride, perchloroethylene, monochloroethane, dichloroethane, tetrachloroethane, perchloroethane, and chlorobenzene, alcoholic and phenolic 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, N-methyl-2-pyrrolidone, acetone, dimethylformamide, and chloroform are particularly preferred. These organic solvents can be used alone or in combination.

[0065] Washing with an organic solvent can be performed by immersing the (a) PPS resin in the organic solvent, with stirring or heating as necessary. There are no particular restrictions on the washing temperature when washing the (a) PPS resin with an organic solvent, and any temperature between room temperature and approximately 300°C can be selected. While higher washing temperatures tend to improve 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 restrictions on the washing time. While it depends on the washing conditions, in the case of batch washing, washing for 5 minutes or more usually produces a sufficient effect. Continuous washing is also possible.

[0066] Examples of methods for alkali metal or alkaline earth metal treatment include adding an alkali metal salt or alkaline earth metal salt before, during, or after the pre-processing step; adding an alkali metal salt or alkaline earth metal salt to the polymerization reactor before, during, or after the polymerization step; or adding an alkali metal salt or alkaline earth metal salt at the beginning, middle, or end of the washing step. Among these, the easiest method is adding an alkali metal salt or alkaline earth metal salt after removing residual oligomers and salts by washing with an organic solvent or warm or hot water. The alkali metal or alkaline earth metal is preferably introduced into the PPS in the form of an alkali metal ion or alkaline earth metal ion, such as an 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 the 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 PPS, 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 the weight of dry PPS) is preferably 0.5 or higher, more preferably 3 or higher, and even more preferably 5 or higher.

[0067] In the present invention, from the viewpoint of further suppressing oxidative crosslinking of the (a) PPS resin under long-term high-temperature environments exceeding 200°C and providing a PPS resin composition with excellent long-term high-temperature durability of mechanical properties, a method in which residual oligomers and residual salts are removed by repeatedly washing with an organic solvent and washing with warm water at about 80°C or the above-mentioned hot water several times, followed by treatment with an acid or an alkali metal salt or an alkaline earth metal salt is preferred, and a method in which treatment with an alkali metal salt or an alkaline earth metal salt is particularly preferred.

[0068] In addition, (a) PPS resin can be used after the polymerization reaction step has been completed by subjecting it to a thermal oxidation crosslinking treatment in which it is heated in an oxygen atmosphere or heated with a crosslinking agent such as peroxide added thereto to increase the molecular weight.

[0069] When dry heat treatment is performed for the purpose of increasing the molecular weight by thermal oxidative crosslinking, the temperature is preferably 160 to 260°C, more preferably 170 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 it is limited to about 50% by volume. The treatment time is preferably 0.5 to 100 hours, more preferably 1 to 50 hours, and even more preferably 2 to 25 hours. The heat treatment device may be a conventional hot air dryer, or a rotary or stirring blade-equipped heating device; however, for efficient and more uniform treatment, it is more preferable to use a rotary or stirring blade-equipped heating device.

[0070] Dry heat treatment can also be performed to suppress thermal oxidative crosslinking and remove volatiles. The temperature is preferably 130 to 250°C, more preferably 160 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; however, for efficient and more uniform treatment, it is more preferable to use a rotary or stirring blade-equipped heating device.

[0071] To improve reactivity with additives, the (a) PPS resin of the present invention may have functional groups such as carboxyl groups or amino groups introduced into the terminals or side chains of the PPS resin. A preferred embodiment has a functional group amount of 25 to 400 μmol / g, more preferably 25 to 250 μmol / g, even more preferably 30 to 150 μmol / g, and most preferably 30 to 80 μmol / g. A functional group amount of 25 μmol / g or more is preferred because it ensures reactivity with additives. On the other hand, a functional group amount of 400 μmol / g or less in the PPS resin is preferred because it can suppress deterioration in processability, flame retardancy, and chemical resistance that accompany an increase in the amount of volatile components.

[0072] Examples of methods for introducing functional groups such as carboxyl groups and amino groups into the (a) PPS resin include copolymerizing a polyhalogenated aromatic compound containing carboxyl groups or amino groups with a sulfidizing agent, and adding a compound containing carboxyl groups or amino groups, such as maleic anhydride or sorbic acid, and reacting it with the (a) PPS resin while melt-kneading. The type of functional group is preferably a carboxyl group or an amino group.

[0073] (2) PPS resin composition The PPS resin composition of the present invention is prepared by blending (a) a PPS resin, and is characterized in that, in an absorption spectrum obtained by infrared spectroscopy (transmission method), an amorphous film (x) of the PPS resin composition and an amorphous film (y) obtained by heat-treating the film at 220°C in the atmosphere for 500 hours exhibit a wavelength of 1210 to 1245 cm. -1 When the maximum peak intensities present in the range are (X) and (Y), respectively, it is necessary to satisfy the following formula (A). (Y)-(X)<0.5 Equation (A)

[0074] One of the objectives of the present invention is to suppress oxidative crosslinking under long-term high-temperature environments, which is an essential problem of (a) PPS resin, and it is essential to incorporate (a) PPS resin. (a) It is believed that oxidative crosslinking of PPS resin proceeds at temperatures exceeding 150°C, resulting in the formation of a diphenyl ether structure, which is observed at 1240 cm in the absorption spectrum obtained by infrared spectroscopy. -1This can be determined from the peak near the C-O-C antisymmetric stretching vibration (see JP-A-2-209925). That is, in the present invention, satisfying formula (A) means that oxidative crosslinking of the (a) PPS resin in the PPS resin composition is suppressed in environments exceeding 200°C. Regarding formula (A), if (Y)-(X) ≥ 0.5, this means that oxidative crosslinking of the (a) PPS resin is not suppressed, and the PPS resin composition cannot maintain its mechanical properties after long-term, high-temperature durability testing. Regarding formula (A), from the viewpoint of suppressing oxidative crosslinking of the (a) PPS resin and ensuring excellent mechanical properties after long-term, high-temperature durability testing, (Y)-(X) ≤ 0.4 is preferred, (Y)-(X) < 0.4 is more preferred, and (Y)-(X) ≤ 0.3 is even more preferred. While there is no particular lower limit, a preferred example is (Y)-(X) ≥ 0. This indicates that oxidative crosslinking of the (a) PPS resin is almost completely suppressed.

[0075] In the present invention, whether the PPS resin composition satisfies formula (A) can be confirmed by the following method. Step 1) Pellets of the PPS resin composition are pressed in a press at 320°C for 2 minutes, and then quenched in a water bath to obtain an amorphous film (x) having a thickness of about 200 µm. Step 2) A portion of the amorphous film (x) is cut out and heat-treated in a hot air oven at 220°C in the atmosphere for 500 hours to obtain a film (y'). Step 3) Using the film (y'), obtain an amorphous film (y) in the same manner as in Step 1. Step 4) Using the amorphous film (x) and the amorphous film (y), respectively, as samples, Fourier transform infrared spectroscopy (FT-IR) is measured using an IR-810 infrared spectrophotometer manufactured by JASCO Corporation. Step 5) The obtained absorption spectrum is measured at 1900 cm -1 Normalized by the intensity of the peak, 1210-1245 cm -1 The maximum peak intensities (X) and (Y) present in the range are obtained, respectively. Step 6) Apply the values ​​of (X) and (Y) to equation (A) and check whether (Y)-(X)<0.5.

[0076] The amount of (a) PPS resin in the PPS resin composition of the present invention is preferably 50% by weight or more, more preferably 60% by weight or more, even more preferably 80% by weight or more, and particularly preferably 90% by weight or more, so that the PPS resin composition has excellent mechanical properties after long-term, high-temperature durability treatment and exhibits the inherent chemical resistance and flame retardancy of (a) PPS resin. The amount is most preferably 95% by weight or more. There is no particular upper limit, but an example is 99.999% by weight or less.

[0077] The PPS resin composition of the present invention preferably has a tensile strength retention of 100% or more, as measured using an ASTM No. 4 dumbbell obtained by injection molding the PPS resin composition under conditions of a pulling speed of 10 mm / min, a gripper distance of 64 mm, and an ambient temperature of 23°C, and calculated using the following formula (B). The tensile strength retention of the PPS resin composition is preferably 105% or more, and more preferably 110% or more. This means that the PPS resin composition has excellent long-term high-temperature durability of mechanical properties in environments exceeding 200°C. (Tensile strength after heat treatment at 220°C for 250 hours in air) / (Tensile strength before heat treatment) × 100 Formula (B)

[0078] The tensile strength of an ASTM No. 4 dumbbell obtained by injection molding the PPS resin composition of the present invention, measured without heat treatment (tensile strength before heat treatment), is preferably 40 MPa or more, more preferably 50 MPa or more, 60 MPa or more, 70 MPa or more, and particularly preferably 80 MPa or more, from the viewpoint of excellent mechanical properties. One example of a method for obtaining such a tensile strength is to (a) set the weight-average molecular weight of the PPS resin to 50,000 or more.

[0079] The method for making the PPS resin composition of the present invention satisfy formula (A) or formula (B) is not particularly limited as long as such a PPS resin composition can be obtained, but preferred examples include a PPS resin composition further containing a (b) metal salt, wherein the (b) metal salt is (b1) a nickel salt, a (b2) alkali metal salt or a (b3) alkaline earth metal salt in which the ionic radius ratio of the constituting anion and cation and the pKa of the conjugate acid of the anion satisfy specific conditions, and wherein the (b) metal salt is a compound containing iodine.

[0080] The PPS resin composition of the present invention preferably has a crystallization peak heat quantity (ΔHmc) of 1 J / g or more when measured by differential scanning calorimetry using a film (y') made of the PPS resin composition. The ΔHmc value of the PPS resin composition decreases with heat treatment, except when the PPS resin composition contains an additive that acts as a crystal nucleating agent for the PPS resin. This is because (a) oxidative crosslinking of the PPS resin progresses, restricting the movement of the polymer molecular chains and making crystallization more difficult. The ΔHmc value is more preferably 10 J / g or more, even more preferably 15 J / g or more, and particularly preferably 20 J / g or more. Such a PPS resin composition can be obtained, for example, by further blending a (b) metal salt into the PPS resin composition, and further blending the (b) metal salt with (b1) a nickel salt, blending with a (b2) alkali metal salt or (b3) alkaline earth metal salt in which the ionic radius ratio of the constituting anion and cation and the pKa of the conjugate acid of the anion satisfy specific conditions, and in addition, the (b) metal salt is a compound containing iodine, and using a (a) PPS resin having a cooling-down crystallization peak temperature of 200°C or less.

[0081] The PPS resin composition of the present invention preferably has a melt viscosity of 500 Pa·s or less at a shear rate of 1216 / s, as measured using a capillograph at 300°C under conditions of orifice length L (mm) / orifice diameter D (mm) = 10. A melt viscosity of 500 Pa·s or less provides excellent fluidity to the PPS resin composition, which is advantageous from the viewpoint of moldability. The melt viscosity is more preferably 450 Pa·s or less, and particularly preferably 400 Pa·s or less. From the viewpoint of preventing burrs during molding, a preferred lower limit is, for example, 100 Pa·s or more.

[0082] (3) Metal salts The PPS resin composition of the present invention preferably contains (b) a metal salt, and furthermore, it is preferable that (b) the metal salt satisfies any one of the following conditions 1 to 3. Condition 1: (b) The metal salt is (b1) a nickel salt. Condition 2: (b) The metal salt is (b2) an alkali metal salt, and the ionic radius ratio of the anion and cation constituting the salt is 2.7 or more, and the pKa of the conjugate acid of the anion is -9.5 or less. Condition 3: (b) The metal salt is (b3) an alkaline earth metal salt, the ionic radius ratio of the constituting anion to the constituting cation is 1.7 or more, and the pKa of the conjugate acid of the anion is −9.5 or less.

[0083] By blending the above-mentioned (b) metal salt into the PPS resin composition, the terminals of the PPS resin, particularly the carboxyl groups, are stabilized through interaction or reaction with the metal salt, making it possible to suppress oxidative crosslinking of the PPS resin in environments exceeding 200°C, and resulting in a PPS resin composition with excellent long-term high-temperature durability of mechanical properties.

[0084] A large ionic radius ratio between the anion and cation constituting the (b2) alkali metal salt or (b3) alkaline earth metal salt means high polarization. A small pKa value of the conjugate acid of the anion means that the anion is highly stable and easily detached. In other words, (b2) alkali metal salts or (b3) alkaline earth metal salts that satisfy both of these conditions are preferred because they readily interact with or react with the PPS resin terminals, thereby providing a sufficient stabilization effect for the PPS resin terminals.

[0085] (b2) In the case of alkali metal salts, the ionic radius ratio is more preferably 2.8 or more, particularly preferably 3.0 or more. There is no particular upper limit, but a preferable example is substantially 5.0 or less. The pKa of the conjugate acid of the anion is more preferably -10 or less. There is no particular lower limit, but a preferable example is approximately -12 or more.

[0086] (b3) In the case of alkaline earth metal salts, the ionic radius ratio is preferably 1.8 or more, more preferably 2.2 or more, and particularly preferably 3.0 or more. There is no particular upper limit, but a preferable example is substantially 7.5 or less. The pKa of the conjugate acid of the anion is more preferably -10 or less. There is no particular lower limit, but a preferable example is approximately -12 or more.

[0087] (b) The ionic radii of the anions and cations constituting metal salts can be found in, for example, Shannon et al., Acta Cryst., 1976, A32, 751; Jenkins et al., J. Chem. Educ., 1979, 56, 576; and Romanova et al., Russ. Chem. Rev., 1975, 44, 1036. The ionic radius ratio can be calculated by dividing the ionic radius of the anion by the ionic radius of the cation. Furthermore, the pKa data for the conjugate acid of the anion in water can be found, for example, at the following URL address: http: / / www.chem.wisc.edu / areas / organic / index-chem.htm Furthermore, the (b) metal salt blended in the PPS resin composition of the present invention is preferably a compound containing iodine. Iodine-containing compounds can remain stable in the PPS resin composition even in environments exceeding 200°C, and are thought to exhibit a high antioxidant effect over a long period of time. In the present invention, the term "iodine-containing compound" refers to a compound containing at least one iodine atom in one molecule.

[0088] From the viewpoint of exhibiting an excellent antioxidant effect, (a) suppressing oxidative crosslinking of the PPS resin, and maintaining the mechanical properties of the PPS resin composition after long-term, high-temperature durability treatment, the proportion of iodine in one molecule of the iodine-containing compound is preferably 50% by weight or more, more preferably 60% by weight or more, even more preferably 75% by weight or more, and particularly preferably 80% by weight or more.

[0089] In the present invention, the amount of (b) metal salt to be blended is, from the viewpoints of suppressing oxidative crosslinking of the (a) PPS resin and maintaining the mechanical properties of the PPS resin composition after long-term, high-temperature durability treatment, preferably 0.01 part by weight or more, more preferably 0.03 part by weight or more, 0.1 part by weight or more, 0.2 part by weight or more, 0.5 part by weight or more, and even more preferably 0.7 part by weight or more, per 100 parts by weight of the (a) PPS resin in the PPS resin composition. There is no particular upper limit, but from the viewpoint of maintaining toughness without impairing the inherent properties of the (a) PPS resin, it is preferably 10 parts by weight or less, more preferably 8 parts by weight or less, more preferably 5 parts by weight or less, 3 parts by weight or less, and particularly preferably 1 part by weight or less.

[0090] When the (b) metal salt is present in the form of a filler in the PPS resin composition of the present invention, the average primary particle size of the (b) metal salt in the PPS resin composition is preferably 1 μm or less, more preferably 500 nm or less, more preferably 100 nm or less, and particularly preferably 50 nm or less, from the viewpoint of the PPS resin composition exhibiting excellent mechanical properties and toughness. The average primary particle size of the (b) metal salt in the PPS resin composition can be determined by observation with a transmission electron microscope.

[0091] Specific examples of preferred metal salts include nickel iodide in the case of (b1) transition metal salts, lithium iodide in the case of (b2) alkali metal salts, and magnesium iodide and calcium iodide in the case of (b3) alkaline earth metal salts, with nickel iodide and lithium iodide being particularly preferred. The (b) metal salts may be either anhydrous or hydrated. In the present invention, multiple (b) metal salts may be used in combination.

[0092] Copper compounds and iron compounds are known to decompose hydroperoxides through a redox reaction, generating radicals. In the PPS resin composition of the present invention, copper compounds and iron compounds also promote radical generation under long-term, high-temperature conditions, which tends to accelerate oxidative crosslinking of the PPS resin composition and reduce its long-term high-temperature durability. Therefore, the amount of copper compound is preferably 0.3 parts by weight or less, more preferably 0.1 parts by weight or less, and particularly preferably 0.05 parts by weight or less. The lower limit is preferably 0 parts by weight, meaning that substantially no copper compounds or iron compounds are used.

[0093] (4)(c) Other additives To the PPS resin composition according to an embodiment of the present invention, (a) a resin other than the PPS resin may be added within a range that does not impair the effects of the present invention. Specific examples of such resins include, but are not limited to, olefin elastomers, polyamides, polybutylene terephthalate, polyethylene terephthalate, polyetherimides, polyetherimide-siloxane copolymers, polyketones, liquid crystal polymers, polyether ketones, polyether ether ketones, fluororesins (polytetrafluoroethylene (PTFE), ethylene-tetrafluoroethylene copolymers (ETFE), tetrafluoroethylene-perfluoro(alkyl vinyl ether) copolymers (PFA), tetrafluoroethylene-hexafluoropropylene copolymers (FEP), ethylene-tetrafluoroethylene-hexafluoropropylene copolymers, polyvinylidene fluoride (PVDF), polychlorotrifluoroethylene (PCTFE), and silicone elastomers. The amount of such resins added is preferably less than 10 parts by weight, more preferably less than 5 parts by weight, and even more preferably less than 3 parts by weight, relative to 100 parts by weight of the (a) PPS resin. The lower limit is preferably 0 parts by weight, i.e., no such resins are included.

[0094] The PPS resin composition of the present invention can contain the following compounds for the purpose of modifying its properties: Plasticizers such as polyalkylene oxide oligomer compounds, thioether compounds, ester compounds, and organophosphorus compounds; nucleating agents such as organophosphorus compounds and polyether ether ketone; metal soaps such as Montan acid waxes, lithium stearate, and aluminum stearate; release agents such as ethylenediamine-stearic acid-sebacic acid polycondensates; water; lubricants; UV inhibitors; color inhibitors; colorants; foaming agents; phosphorus-based flame retardants; halogen-based flame retardants; and inorganic flame retardants. More than 10 parts by weight of any of the above compounds per 100 parts by weight of (a) PPS resin is undesirable because it can impair the inherent properties of the PPS resin composition of the present invention and promote oxidative crosslinking under long-term high-temperature conditions. Amounts of 5 parts by weight or less, 1 part by weight or less, and even less than 0.3 parts by weight are preferred.

[0095] In the present invention, an organic silane compound or an epoxy resin can be added to the PPS resin composition in order to increase its toughness.

[0096] Specific examples of the organic silane compound are preferably organic silane compounds having at least one functional group selected from an isocyanate group, an epoxy group, an amino group, a hydroxyl group, a mercapto group, a ureido group, and an alkoxy group. Specific examples include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldiethoxysilane, N-phenylaminomethyltrimethoxysilane, and N-phenylaminopropyl. Preferred examples of the silane include 3-isocyanatopropyltrimethoxysilane, dimethoxymethyl-3-piperazinopropylsilane, 3-piperazinopropyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane, 3-isocyanatopropylmethyldimethoxysilane, 3-isocyanatopropylmethyldiethoxysilane, 3-isocyanatopropylethyldimethoxysilane, 3-hydroxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptomethyldimethoxysilane, and γ-ureidopropyltrimethoxysilane.

[0097] Among the above-mentioned organic silane compounds, 3-isocyanatopropyltriethoxysilane, 3-aminopropyltriethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane are preferred from the viewpoints of reactivity and ease of handling.

[0098] These alkoxy organic silane compounds can be used alone or in the form of a mixture of two or more kinds.

[0099] The amount of the organosilane compound used in the present invention is preferably 0.01 to 10 parts by weight, more preferably 0.1 to 5 parts by weight, and even more preferably 0.3 to 3 parts by weight, per 100 parts by weight of the (a) PPS resin. Setting the amount of the organosilane compound to 10 parts by weight or less is preferred because it allows the flame retardancy of the resulting PPS resin composition to be maintained. A blending amount of the organosilane compound of 0.01 parts by weight or more is preferred because it allows sufficient reaction between PPS and the organosilane compound, resulting in excellent toughness.

[0100] Specific examples of epoxy resins include bisphenol A epoxy resins, bisphenol F epoxy resins, brominated epoxy resins, special skeleton bifunctional epoxy resins having a biphenyl skeleton or a naphthalene skeleton, glycidyl ether epoxy resins such as cresol novolac, trisphenolmethane, and dicyclopentadiene polyfunctional epoxy resins, glycidyl amine epoxy resins such as aromatic amine and aminophenol types, and glycidyl ester epoxy resins such as hydrophthalic acid and dimer acid types. The amount of such epoxy resin added is preferably 0.1 to 5 parts by weight, and more preferably 0.2 to 3 parts by weight, per 100 parts by weight of the (a) PPS resin.

[0101] Although not an essential component, inorganic fillers can be blended and used in the PPS resin composition of the present invention within the scope that does not impair the effects of the present invention. Specific examples of such inorganic fillers include fibrous fillers such as glass fiber, carbon fiber, carbon nanotube, carbon nanohorn, potassium titanate whisker, zinc oxide whisker, calcium carbonate whisker, wollastonite whisker, aluminum borate whisker, aramid fiber, alumina fiber, silicon carbide fiber, ceramic fiber, asbestos fiber, gypsum fiber, and metal fiber; fullerene, talc, wollastonite, zeolite, sericite, mica, kaolin, clay, pyrophyllite, bentonite, asbestos, and alumina silica. Examples of inorganic fillers include silicates such as silicate carbonate, silicon oxide, 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; and non-fibrous fillers such as glass beads, glass flakes, glass powder, ceramic beads, boron nitride, silicon carbide, carbon black, and graphite. Among these, glass fiber, calcium carbonate, and carbon black are preferred, with calcium carbonate and carbon black being particularly preferred for their corrosion prevention and lubricating properties. These inorganic fillers may be hollow, and two or more types may be used in combination. These inorganic fillers may also be pretreated with a coupling agent such as an isocyanate compound, an organosilane compound, an organotitanate compound, an organoborane compound, or an epoxy compound.

[0102] When the PPS resin composition is used in applications requiring toughness and flexibility, as typified by tensile elongation, the amount of inorganic filler added is selected to be less than 10 parts by weight, preferably less than 5 parts by weight, more preferably less than 3 parts by weight, and even more preferably 1 part by weight or less, per 100 parts by weight of (a) PPS resin. There is no particular lower limit, but 0.0001 parts by weight or more is preferred. On the other hand, when the PPS resin composition is used in applications requiring high strength and high rigidity, the amount is preferably 20 parts by weight or more, more preferably 40 parts by weight or more, more preferably 60 parts by weight or more, and particularly preferably 100 parts by weight or more, per 100 parts by weight of (a) PPS resin. There is no particular upper limit, but 200 parts by weight or less is preferred to avoid excessive impairment of toughness and melt processability.

[0103] Among the above-mentioned compounds, low-molecular-weight organic compounds tend to decompose easily under long-term, high-temperature conditions and generate radicals, which accelerates oxidative crosslinking of the PPS resin composition and reduces its long-term, high-temperature durability. Therefore, in the PPS resin composition of the present invention, the amount of low-molecular-weight organic compound is preferably 0.6 parts by weight or less, more preferably 0.3 parts by weight or less, and particularly preferably 0.1 parts by weight or less, per 100 parts by weight of (a) PPS resin. The lower limit is preferably 0 parts by weight, meaning that substantially no low-molecular-weight organic compound is incorporated. Note that the term "low-molecular-weight organic compound" refers to a compound having a molecular weight of 800 or less, containing at least one carbon atom in its chemical structure, and having a weight ratio of carbon atoms to hydrogen atoms of 70% or more.

[0104] (5) Method for producing PPS resin composition Methods for producing the PPS resin composition of an embodiment of the present invention include production in a molten state and 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 allows continuous production is preferred. For melt kneading using an extruder, at least one extruder 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. From the viewpoints of kneading ability, reactivity, and improved productivity, multi-screw extruders such as a twin-screw extruder and a four-screw extruder are preferred, and melt kneading using a twin-screw extruder is most preferred.

[0105] A more specific method of melt-kneading is, but is not necessarily limited to, a twin-screw extruder having an L / D (L: screw length, D: screw diameter) ratio of 10 or more, preferably 20 or more, and two or more, preferably three or more kneading sections. There is no particular upper limit to the L / D ratio, but from an economical standpoint, it is preferably 60 or less. There is also no particular upper limit to the number of kneading sections, but from a productivity standpoint, it is preferably 10 or less. From the standpoint of dispersibility of additives in the PPS resin, the ratio of kneading sections to the total screw length is preferably 5% or more, more preferably 10% or more, and even more preferably 15% or more. Meanwhile, the upper limit of the ratio of kneading sections to the total screw length is preferably 40% or less, from the standpoint of preventing deterioration of the resin due to excessive shear heat generation during kneading.

[0106] The screw rotation speed is preferably 150 to 1,000 rpm, more preferably 300 to 1,000 rpm, and even more preferably 350 to 800 rpm. When the screw rotation speed exceeds 150 rpm, the kneading force is sufficient, suppressing aggregation of the (b) iodine-containing compound and other additives, leading to the development of desired toughness. When the screw rotation speed exceeds 1,000 rpm, excessive shear heat generation during kneading can cause deterioration of the resin and additives, leading to reduced toughness, reduced mold fouling, and flashing due to reduced melt viscosity, which is undesirable.

[0107] Specifically, the preferred range of the cylinder temperature (°C) is 280 to 400°C, more preferably 280 to 360°C, and even more preferably 280 to 330°C.

[0108] The order of mixing the raw materials when melt-kneading is not particularly limited, and any of the following methods may be used: a method in which all raw materials are blended and then melt-kneaded by the above-mentioned method; a method in which some raw materials are blended and then melt-kneaded by the above-mentioned method, and then the remaining raw materials are blended and melt-kneaded; or a method in which some raw materials are blended and then the remaining raw materials are mixed using a side feeder while being melt-kneaded by a twin-screw extruder.

[0109] (6) Uses of PPS resin compositions The PPS resin composition of the present invention can be molded by various molding techniques, such as injection molding, extrusion molding, compression molding, blow molding, and injection-compression molding. The PPS resin composition of the present invention has excellent flowability and excellent mechanical properties after long-term, high-temperature durability treatment, making it suitable for injection molding, which requires good flowability. Because of its excellent mechanical properties after long-term, high-temperature durability treatment, the PPS resin composition of the present invention is also useful for extrusion molding, which requires a relatively high molding temperature and a long melt residence time.

[0110] Applications of molded products obtained by injection molding include electrical equipment parts such as generators, electric motors, transformers, current transformers, voltage regulators, rectifiers, inverters, relays, power contacts, switches, circuit breakers, knife switches, polarity rods, and electrical component cabinets; sensors, LED lamps, connectors, sockets, resistors, relay cases, small 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, etc. Electronic components such as folders, parabolic antennas, and computer-related components; VTR components, television components, irons, hair dryers, rice cooker components, microwave oven components, acoustic components, audio equipment components such as laser discs and compact discs; home and office electrical appliance components such as lighting components, refrigerator components, air conditioner components, typewriter components, and word processor components; machinery components such as office computer components, telephone components, facsimile components, copier components, cleaning tools, motor components, lighters, and typewriters; optical and precision machinery components such as microscopes, binoculars, cameras, and watches;Alternator terminals, alternator connectors, IC regulators, potentiometer bases for light dimmers, various valves such as exhaust gas valves, various pipes and ducts for fuel, exhaust and intake systems, turbo ducts, air intake nozzle snorkels, intake manifolds, fuel pumps, engine coolant joints, carburetor main bodies, carburetor spacers, exhaust gas sensors, coolant sensors, oil temperature sensors, brake pad wear sensors, throttle position sensors, crankshaft position sensors, air flow meters, brake pad wear sensors, air conditioner thermostat bases, heating hot air flow control valves, brush holders for radiator motors, water pump impellers Examples include automotive and vehicle-related parts such as turbine vanes, wiper motor 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, crash pads, insulation ties, cable ties, and ignition device cases; and gaskets for primary or secondary batteries in mobile phones, smartphones, laptops, tablet computers, video cameras, hybrid cars, electric cars, etc.;

[0111] Examples of molded products obtained by extrusion include round bars, square bars, sheets, films, tubes, and pipes. Specific applications include electrical insulating materials for water heater motors, air conditioner motors, and drive motors, film capacitors, speaker diaphragms, recording magnetic tape, printed circuit board materials, printed circuit board peripheral components, seamless belts, semiconductor packages, semiconductor carrier trays, process and release films, protective films, automotive film sensors, insulating tape for wire cables, insulating washers in lithium-ion batteries, tubing for hot water, coolant, and chemicals, automotive fuel tubing, hot water piping, chemical piping in chemical plants, piping for ultrapure water and ultrapure solvents, automotive piping, piping for chlorofluorocarbons and supercritical carbon dioxide refrigerants, and workpiece retaining rings for polishing equipment. Other examples include coated molded articles for motor coil windings in hybrid vehicles, electric vehicles, railways, and power generation equipment; heat-resistant electrical wires and cables for home appliances; wire harnesses and control wires, such as flat cables used in automotive wiring; and coated molded articles for windings of signal transformers or on-board transformers for communication, transmission, high-frequency, audio, and measurement applications.

[0112] Examples of uses for molded articles obtained by blow molding include automobile fuel tanks, oil tanks, resonators, intercoolers, intake manifolds, turbo ducts, intake and exhaust ducts, radiator pipes, radiator headers, expansion tanks, and oil circulation pipes.

[0113] Among the above-mentioned molded products, they are particularly useful as automotive components exposed to high-temperature environments, such as various pipes and ducts for fuel, exhaust, and intake systems, motor peripheral components and power transmission components for hybrid and electric vehicles, railways, and power generation facilities, particularly steering gears, covering materials for electric wires, and automotive binding bands.

[0114] The PPS resin composition of the present invention is particularly suitable for use in electric wire coatings and plastic fasteners because of its excellent mechanical properties after long-term, high-temperature durability treatment. When used in electric wire coatings, especially those with heat-generating temperatures exceeding 200°C, it is possible to prevent deterioration of insulation due to cracking. Furthermore, when used in plastic fasteners, which are components that are subjected to long-term external forces, it is possible to maintain its shape in long-term, high-temperature environments.

[0115] These various molded products can also be subjected to secondary processing such as hot plate welding, laser welding, induction heating welding, high frequency welding, spin welding, vibration welding, ultrasonic welding, and injection welding. [Example]

[0116] The present invention will be explained in more detail below by way of examples, but the present invention is not limited to these examples.

[0117] In the examples and comparative examples, the following were used as (a) PPS resin, (b) metal salt, and (c) other additives.

[0118] [(a)PPS resin (a-1)] [Reference example 1 PPS resin (a-1)] An autoclave equipped with a stirrer was charged with 8267.37 g (70.00 mol) of 47.5% sodium hydrosulfide, 2923.88 g (70.17 mol) of 96% sodium hydroxide, 11434.50 g (115.50 mol) of N-methyl-2-pyrrolidone (NMP), 1894.20 g (23.10 mol) of sodium acetate, and 10500 g of ion-exchanged water. The mixture was gradually heated to 230 °C over approximately 3 hours under atmospheric pressure while passing nitrogen through. After distilling off 14780.1 g of water and 280 g of NMP, the reaction vessel was cooled to 160 °C. The amount of water remaining in the system per mole of charged alkali metal sulfide was 1.06 mol, including the water consumed in the hydrolysis of NMP. The amount of hydrogen sulfide released was 0.017 mol per mole of charged alkali metal sulfide.

[0119] Next, 10,420 g (70.89 mol) of p-dichlorobenzene and 9078.30 g (91.70 mol) of NMP were added, and the reaction vessel was sealed under nitrogen gas. While stirring at 240 rpm, the temperature was increased to 240 ° C at a rate of 0.6 ° C / min. After 40 minutes of reaction at 240 ° C, the temperature was increased to 275 ° C at a rate of 0.8 ° C / min. 2,394 g (133 mol) of ion-exchanged water was then pressure-charged into the autoclave while cooling to 250 ° C at a rate of 1.3 ° C / min. The mixture was then cooled to 200 ° C at a rate of 1.0 ° C / min and then rapidly cooled to near room temperature.

[0120] The contents were removed and diluted with 26,300 g of NMP. The solvent and solids were filtered through a sieve (80 mesh). The resulting particles were washed with 31,900 g of NMP and filtered. These were washed several times with 56,000 g of ion-exchanged water and filtered, and then washed with 70,000 g of 0.05 wt% acetic acid aqueous solution and filtered. After washing with 70,000 g of ion-exchanged water and filtering, the resulting hydrous PPS particles were dried with hot air at 80°C and then dried under reduced pressure at 120°C. The resulting PPS resin (a-1) had a weight-average molecular weight of 73,000, a melting point of 280°C, and a cooling crystallization peak temperature of 229°C.

[0121] [Reference example 2 PPS resin (a-2)] An autoclave equipped with a stirrer was charged with 826 kg (70.0 mol) of 47.5% sodium hydrosulfide, 2.94 kg (70.6 mol) of 96% sodium hydroxide, 11.45 kg (115.5 mol) of NMP, 2.58 kg (31.5 mol) of sodium acetate, and 5.50 kg of ion-exchanged water. The mixture was gradually heated to 240 °C under atmospheric pressure while passing nitrogen through it. Heating was stopped and cooling commenced when 9.82 kg of water and 0.28 kg of NMP had distilled off. At this point, the amount of water remaining in the system per mole of alkali metal hydrosulfide charged was 1.01 mol, including the water consumed in the hydrolysis of NMP. Furthermore, the amount of hydrogen sulfide released was 1.4 mol, so the amount of sulfiding agent in the system after this dehydration step was 68.6 mol. Note that, with the release of hydrogen sulfide, an additional 1.4 mol of sodium hydroxide was generated in the system.

[0122] Next, 10.24 kg (69.6 mol) of p-dichlorobenzene and 9.37 kg (94.5 mol) of NMP were added, and the reaction vessel was sealed under nitrogen gas. The temperature was raised from 200°C to 235°C while stirring. Polymerization was carried out at 235°C for 120 minutes, followed by heating to 255°C. 1.00 kg (56.0 mol) of ion-exchanged water was then injected, and polymerization reaction was carried out at 255°C for 300 minutes. After completion of the reaction, the mixture was cooled to 200°C at a rate of 1.0°C / min and then rapidly cooled to near room temperature. The mixture was diluted with NMP to form a slurry, which was stirred at 85°C for 30 minutes and then filtered through an 80-mesh wire mesh to obtain a solid. The resulting solid was similarly washed with NMP and filtered. The resulting solid was diluted with ion-exchanged water, stirred at 70°C for 30 minutes, and then filtered through an 80-mesh wire mesh to collect the solid. This procedure was repeated four times. The PPS resin was then washed in an aqueous solution containing 0.5% by weight of calcium acetate per 1 g of PPS resin, and the solid was collected by filtration through an 80-mesh wire screen. The solid thus obtained was dried at 120°C under a nitrogen stream. The resulting PPS resin (a-2) had a weight-average molecular weight of 80,000, a melting point of 275°C, and a peak crystallization temperature upon cooling of 174°C.

[0123] [(b) Metal salt] [(b1) Transition metal salt (b1-1)] b1-1: Nickel iodide (Sigma-Aldrich), iodine content per molecule: 81%, average primary particle size: 24 nm b1'-1: Nickel(II) chloride hexahydrate (Fujifilm Wako Pure Chemical Industries, Ltd.) b1'-2: Copper(II) chloride anhydrous (Tokyo Chemical Industry Co., Ltd.) b1'-3: Iron(II) chloride tetrahydrate (Fujifilm Wako Pure Chemical Industries, Ltd.) b1'-4: Copper(I) iodide (Fujifilm Wako Pure Chemical Industries, Ltd.)

[0124] [(b2) Alkali metal salt (b2-1)] b2-1: Lithium iodide (Fujifilm Wako Pure Chemical Industries, Ltd.), iodine content per molecule: 95% b2'-1: Lithium bromide (Sigma-Aldrich) b2'-2: Lithium chloride (Fujifilm Wako Pure Chemical Industries, Ltd.) b2'-3: Sodium iodide (Fujifilm Wako Pure Chemical Industries, Ltd.) b2'-4: Lithium sulfate (Tokyo Chemical Industry Co., Ltd.) b2'-5: Sodium hypophosphinate monohydrate (Fujifilm Wako Pure Chemical Industries, Ltd.)

[0125] [(b3) Alkaline earth metal salts (b3-1 to 2)] b3-1: Magnesium iodide (Sigma-Aldrich), iodine content per molecule: 91% b3-2: Calcium iodide (Sigma-Aldrich), iodine content per molecule: 86% b3'-1: Barium iodide (Tokyo Chemical Industry Co., Ltd.) b3'-2: Magnesium sulfate (Kanto Chemical Co., Ltd.)

[0126] [(c) Other additives (c-1 to c-4)] c-1: Nickel (Sigma-Aldrich), average primary particle size: <100 nm c-2: AO-80, 3,9-bis{2-[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy]-1,1-dimethylethyl}-2,4,8,10-tetraoxaspiro[5.5]undecane (ADEKA Corporation), molecular weight: 741, weight ratio of carbon atoms to hydrogen atoms: 78% c-3: 3-Isocyanatepropyltriethoxysilane (Shin-Etsu Silicones "KBE9007N"), molecular weight: 247, weight ratio of carbon atoms to hydrogen atoms: 57% c-4: Sodium hydroxide (Fujifilm Wako Pure Chemical Industries, Ltd.)

[0127] In the following examples, material properties were evaluated by the following methods.

[0128] [GPC measurement] The number average molecular weight (Mn) and weight average molecular weight (Mw) of the PPS resin were measured using a gel permeation chromatography (GPC) manufactured by Senshu Scientific Co., Ltd. under the conditions shown below, and calculated in terms of polystyrene. Equipment: Senshu Science SSC-7110 Column name: "Shodex" (registered trademark) 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

[0129] [FT-IR measurement] Pellets of the PPS resin composition were dried at 130°C for 3 hours using a hot air dryer, and then the maximum peak strength was evaluated by the following method, and (Y) - (X) was calculated. Step 1) Pellets of the PPS resin composition were pressed in a press at 320° C. for 2 minutes, and then quenched in a water bath to obtain an amorphous film (x) having a thickness of about 200 μm. Step 2) A part of (x) was cut out and heat-treated in a hot air oven at 220°C in the atmosphere for 500 hours to obtain a film (y'). Procedure 3) Using the film (y'), an amorphous film (y) was obtained in the same manner as in Procedure 1. Step 4) Using the amorphous film (x) and the amorphous film (y), respectively, as samples, Fourier transform infrared spectroscopy (FT-IR) was measured using an IR-810 infrared spectrophotometer manufactured by JASCO Corporation. Step 5) The obtained absorption spectrum is measured at 1900 cm -1 Normalized by the intensity of the peak, 1210-1245 cm -1 The maximum peak intensities (X) and (Y) present in the range were obtained. Step 6) The values ​​of (X) and (Y) were applied to equation (A) to confirm whether (Y)-(X)<0.5.

[0130] [DSC measurement] (a) Using the PPS resin and the films (x) and (y') made of the PPS resin composition, measurements were performed under the following conditions using a differential scanning calorimeter (DSC, Q200; manufactured by TA Instruments) in a nitrogen atmosphere. Film (x) was crystallized by heat treatment at 150°C for 30 minutes in a hot air oven before measurement. The temperature was raised from 50°C to 340°C at a rate of 20°C / min. The sample was then held at 340°C for 1 minute and cooled to 100°C at a rate of 20°C / min. The melting point (Tm) was determined from the melting peak top detected during the heating process, and the cooling crystallization peak temperature (Tmc) was determined from the cooling crystallization peak top detected during the cooling process. The cooling crystallization peak heat quantity (ΔHmc) was also determined from the cooling crystallization peak area. When no peak was observed, it was deemed "no peak."

[0131] [Tensile test] PPS resin composition pellets were dried at 130°C for 3 hours using a hot air dryer and then fed into a Sumitomo Heavy Industries injection molding machine (SE-75DUZ) set at a cylinder temperature of 300°C and a mold temperature of 150°C. ASTM No. 4 dumbbells were molded at an injection speed of 50 mm / s, a molding pressure of 7 MPa (lower limit pressure), an injection time of 15 s, and a cooling time of 10 s. The molded articles were either heat-treated or heat-treated in a hot air oven at 220°C for 250 hours in air, followed by conditioning for 16 hours at an ambient temperature of 23°C and 50% relative humidity. The tensile strength of the conditioned dumbbells was measured using a Tensilon UTA2.5T tensile tester at a pulling speed of 10 mm / min, a grip distance of 64 mm, a gauge length of 50 mm, an ambient temperature of 23°C, and 50% relative humidity. The average of five measurements was calculated using this value to calculate the tensile strength retention using the following formula (B). The "tensile strength before heat treatment" refers to the tensile strength measured using a dumbbell that has been conditioned without heat treatment. (Tensile strength after heat treatment at 220°C for 250 hours in air) / (Tensile strength before heat treatment) × 100 Formula (B)

[0132] [Melt viscosity measurement] PPS resin or PPS resin composition pellets were dried in a hot air dryer at 130°C for 3 hours, and then measured using a capillograph under conditions of 300°C, orifice length L (mm) / orifice diameter D (mm) = 10. The value at a shear rate of 1216 / s was used.

[0133] [Examples 1 to 11, Comparative Examples 1 to 17] PPS resin, metal salts, and other additives were dry-blended according to the formulations shown in Tables 1 to 3, and then the mixture was melt-kneaded in a TEX30α twin-screw extruder (L / D = 30, two kneading sections) manufactured by The Japan Steel Works, Ltd. Note that sodium hydroxide was dissolved in ion-exchanged water to prepare an aqueous solution, which was then mixed with the PPS resin and melt-kneaded so that the sodium hydroxide content achieved the formulation shown in the table. Kneading was performed at a temperature of 300°C and a rotation speed of 200 rpm. After pelletizing using a strand cutter, the pellets were dried at 130°C for 3 hours and then subjected to evaluation. The evaluation results are shown in Tables 1 to 3.

[0134] [Table 1]

[0135] [Table 2]

[0136] [Table 3]

[0137] The results of the above-mentioned Examples and Comparative Examples will be compared and explained.

[0138] A comparison of Examples 1 to 5 and Comparative Examples 1 and 2 shows that the PPS resin composition of the present invention is able to suppress the increase in IR peak intensity before and after heat treatment at 220°C for 500 hours, thereby satisfying formula (A). However, (a) PPS resin alone cannot satisfy formula (A). In other words, it is clear that the PPS resin composition of the present invention is able to suppress oxidative crosslinking under long-term high-temperature environments exceeding 200°C, a problem that conventional PPS resins have. Suppression of oxidative crosslinking is achieved by incorporating nickel iodide as the (b1) transition metal salt and by using an (a) PPS resin with a cooling crystallization peak temperature of 200°C or less.

[0139] In Comparative Examples 3 to 9, 16, and 17, the increase in IR peak intensity before and after heat treatment at 220°C for 500 hours was large, and formula (A) was not satisfied. In other words, it is clear that transition metal salts other than nickel salts, nickel alone, and other known techniques are unable to suppress oxidative crosslinking in a long-term high-temperature environment exceeding 200°C.

[0140] Examples 6 to 11, which contain (b2) alkali metal salt or (b3) alkaline earth metal salt, also satisfy formula (A) and are able to suppress oxidative crosslinking in a long-term high-temperature environment exceeding 200°C. On the other hand, Comparative Examples 10 to 15 do not satisfy formula (A) and are unable to suppress oxidative crosslinking in a long-term high-temperature environment exceeding 200°C. This demonstrates that suppression of oxidative crosslinking can be achieved when the ionic radius ratio of the constituent anion and cation and the pKa of the conjugate acid of the anion satisfy specific conditions.

[0141] As shown in Table 3, the PPS resin composition of the present invention satisfies formula (A) as described above and suppresses oxidative crosslinking. Therefore, it exhibits excellent tensile strength retention before and after heat treatment at 220°C for 250 hours, and excellent long-term high-temperature durability of mechanical properties. On the other hand, if the PPS resin composition does not satisfy formula (A), it can be said that the tensile strength retention is low and the long-term high-temperature durability of mechanical properties is poor. In Comparative Example 9, the dumbbell after heat treatment was so brittle that it broke when clamped between grippers during a tensile test, making it impossible to measure tensile strength. In Comparative Example 17, the molded product obtained under the same molding conditions as the others was in an amorphous state, making it impossible to evaluate the tensile properties before heat treatment. Furthermore, unlike the PPS resin composition of the present invention, the incorporation of additives significantly reduced fluidity.

Claims

1. (a) A polyphenylene sulfide resin composition containing a polyphenylene sulfide resin, wherein an amorphous film (x) of the resin composition and an amorphous film (y) obtained by heat-treating the film at 220°C in the atmosphere for 500 hours are subjected to infrared spectroscopy (transmission method) to obtain an amorphous film (y) having a wave number of 1210 to 1245 cm. －１ When the maximum peak intensities present in the range are (X) and (Y), respectively, the polyphenylene sulfide resin composition satisfies the following formula (A): (Y)-(X)<0.5...Formula (A)

2. The polyphenylene sulfide resin composition according to claim 1, further comprising (b) a metal salt.

3. 3. The polyphenylene sulfide resin composition according to claim 2, wherein the (b) metal salt is (b1) a nickel salt.

4. The polyphenylene sulfide resin composition according to claim 2, wherein the (b) metal salt is (b2) an alkali metal salt, the ionic radius ratio of the constituting anion to the constituting cation is 2.7 or more, and the pKa of the conjugate acid of the anion is −9.5 or less.

5. The polyphenylene sulfide resin composition according to claim 2, wherein the (b) metal salt is (b3) an alkaline earth metal salt, the ionic radius ratio of the constituting anion to the constituting cation is 1.7 or more, and the pKa of the conjugate acid of the anion is −9.5 or less.

6. The polyphenylene sulfide resin composition according to any one of claims 2 to 5, wherein the metal salt (b) is a compound containing iodine.

7. 2. The polyphenylene sulfide resin composition according to claim 1, wherein the polyphenylene sulfide resin (a) has a temperature-lowering crystallization peak temperature of 200° C. or less as determined by differential scanning calorimetry.

8. 2. The polyphenylene sulfide resin composition according to claim 1, wherein the weight average molecular weight of the polyphenylene sulfide resin (a) is 75,000 or more.

9. 2. The polyphenylene sulfide resin composition according to claim 1, wherein the tensile strength retention is measured using an ASTM No. 4 dumbbell obtained by injection molding the polyphenylene sulfide resin composition under conditions of a pulling speed of 10 mm / min, a gripping distance of 64 mm, and an ambient temperature of 23°C, and calculated by the following formula (B) of 100% or more: (Tensile strength after heat treatment at 220°C for 250 hours in air) / (Tensile strength before heat treatment)×100 Formula (B)

10. A molded article comprising the polyphenylene sulfide resin composition according to any one of claims 1 to 5 or 7 to 9.

11. A coating member for an electric wire, comprising the polyphenylene sulfide resin composition according to any one of claims 1 to 5 or 7 to 9.

12. The covering member for an electric wire according to claim 11 , wherein the heat generation temperature exceeds 200° C.

13. A plastic fastener comprising the polyphenylene sulfide resin composition according to any one of claims 1 to 5 or 7 to 9.

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