Polyphenylene sulfide resin composition and molded article

Abstract

This invention provides a PPS resin composition and its molded articles that exhibit excellent tracking resistance and thermal shock resistance. [Solution] A polyphenylene sulfide resin composition comprising (A) a polyphenylene sulfide resin and (B) a non-fibrous inorganic filler having an aspect ratio of 5.0 or less, wherein when a metal insert test piece with a hole in the center to intentionally create a weld area is subjected to thermal shock treatment (treatment at 130°C for 1 hour followed by treatment at -40°C for 1 hour), the polyphenylene sulfide resin composition is subjected to 15 or more treatments before cracks appear in the weld area.

Description

Technical Field

[0001] The present invention relates to a polyphenylene sulfide resin composition excellent in tracking resistance and cold and heat shock resistance, and a molded product thereof.

Background Art

[0002] Polyphenylene sulfide (hereinafter sometimes abbreviated as PPS) resin is an engineering plastic excellent in heat resistance, flame retardancy, chemical resistance, electrical insulation, heat and moisture resistance, mechanical strength, dimensional stability, etc. Since PPS resin can be molded into various molded products, fibers, films, etc. by various molding methods such as injection molding and extrusion molding, it is used in a wide range of fields such as electric and electronic parts, mechanical parts, and automotive parts.

[0003] In recent years, with the increase in the output of electric vehicles, the amount of heat generated tends to increase, so the need for a resin composition having excellent heat resistance such as PPS resin has been increasing.

[0004] In addition, many resin molded products with metal inserts such as busbars, current sensors, and power modules are installed in electric vehicles. A resin composition excellent in cold and heat shock resistance is required, which does not cause cracks in the metal insert molded products even when the ambient temperature changes between high and low.

[0005] On the other hand, regarding tracking breakdown that occurs when a high voltage is applied to the surface of an insulator, PPS resin is inferior compared to other engineering plastics such as polyamide resin and polyester resin.

[0006] Therefore, despite its excellent heat resistance, flame retardancy, chemical resistance, electrical insulation, moisture and heat resistance, mechanical strength, and dimensional stability, the use of PPS resin is restricted in environments exposed to relatively high voltages. In recent years, the rated voltage has tended to rise due to the increased power output and rapid charging capabilities of electric vehicles. Furthermore, the need to ensure creepage distances of components exceed the required creepage distance specified in IEC60664, in order to miniaturize and lighten components, has led to a demand for PPS resin with superior tracking resistance.

[0007] Attempts have been made to improve the tracking resistance of PPS resin. For example, Patent Document 1 describes how adding magnesium hydroxide and an ethylene-vinyl alcohol copolymer to PPS resin improves tracking resistance. Patent Document 2 describes how adding magnesium oxide, a thermally conductive filler, improves tracking resistance. Patent Document 3 describes how adding magnesium hydroxide, which has a high apparent specific gravity, to PPS resin stabilizes the productivity of PPS resin with excellent tracking resistance. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2014-145006 [Patent Document 2] Japanese Patent Publication No. 2013-76039 [Patent Document 3] International Publication No. 2015 / 137228 [Overview of the project] [Problems that the invention aims to solve]

[0009] However, while the resin composition described in Patent Document 1 has improved tracking resistance due to the inclusion of a large amount of magnesium hydroxide and an ethylene-vinyl alcohol copolymer, it does not provide any specific description regarding thermal shock resistance. Furthermore, because it contains a large amount of magnesium hydroxide with a large aspect ratio, its thermal shock resistance is considered insufficient.

[0010] The resin composition described in Patent Document 2 has improved tracking resistance due to the inclusion of a large amount of magnesium oxide, but there is no specific description regarding thermal shock resistance. Furthermore, because it contains a large amount of thermally conductive filler with a large aspect ratio, its thermal shock resistance is considered insufficient.

[0011] Although the resin composition described in Patent Document 3 has improved tracking resistance due to the inclusion of a large amount of magnesium hydroxide, there is no specific description regarding thermal shock resistance. Furthermore, the resin composition specifically shown in the examples does not contain irregularly shaped cross-section glass or elastomers, and therefore its thermal shock resistance is considered insufficient.

[0012] Therefore, the object of the present invention is to provide a PPS resin composition and its molded articles that have excellent tracking resistance and thermal shock resistance. [Means for solving the problem]

[0013] To solve the above problems, the present invention has the following configuration. That is, (1) A polyphenylene sulfide resin composition comprising (A) a polyphenylene sulfide resin and (B) a non-fibrous inorganic filler having an aspect ratio of 5.0 or less, wherein when a metal insert test piece with a hole in the center to intentionally create a weld area is subjected to thermal shock treatment (treatment at 130°C for 1 hour followed by treatment at -40°C for 1 hour), the number of treatments required for cracks to occur in the weld area is 15 or more. (2)(B) The polyphenylene sulfide resin composition according to (1), wherein the average particle size of the non-fibrous inorganic filler is 0.1 μm or more and 50.0 μm or less. (3) A polyphenylene sulfide resin composition according to (1) or (2), comprising 20 to 170 parts by mass of (B) a non-fibrous inorganic filler per 100 parts by mass of (A) polyphenylene sulfide resin. (4) The polyphenylene sulfide resin composition according to any one of (1) to (3), wherein the (B) non-fibrous inorganic filler is a decomposition endothermic filler. (5) A polyphenylene sulfide resin composition according to any one of (1) to (4), comprising 100 parts by mass of (A) polyphenylene sulfide resin and 40 to 190 parts by mass of (C) fibrous inorganic filler. (6)(C) The polyphenylene sulfide resin composition according to (5), wherein the fibrous inorganic filler is a glass fiber with a deformed cross-section and a deformed ratio of 1.3 to 10. (7) A polyphenylene sulfide resin composition according to any one of (1) to (6), comprising 100 parts by mass of (A) polyphenylene sulfide resin and 1 to 40 parts by mass of (D) elastomer. (8) A polyphenylene sulfide resin composition according to any one of (1) to (7), wherein the comparative tracking index value measured in accordance with IEC60112(2003) is 300V or higher. (9) A molded article comprising a polyphenylene sulfide resin composition as described in any of (1) to (8). An automotive electrical component comprising the polyphenylene sulfide resin composition described in any of (10)(1) to (8). (11) A current sensor comprising the polyphenylene sulfide resin composition described in any of (1) to (8). A bus bar comprising the polyphenylene sulfide resin composition described in any of (12)(1) to (8). (13) A power semiconductor housing comprising a polyphenylene sulfide resin composition as described in any of (1) to (8). [Effects of the Invention]

[0014] According to the present invention, it is possible to provide a PPS resin composition excellent in tracking resistance and cold and heat shock resistance, and a molded product thereof. With this PPS resin composition, miniaturization and weight reduction of the molded product can be achieved, and metal insert molding of various complex shapes becomes possible, achieving an improvement in the design freedom and safety of the molded product.

Brief Description of the Drawings

[0015] [Figure 1] It is a schematic diagram of a test piece used for evaluating cold and heat shock resistance.

Modes for Carrying Out the Invention

[0016] Hereinafter, embodiments of the present invention will be described in detail.

[0017] (A) PPS resin The PPS resin used in the embodiments of the present invention is a polymer having a repeating unit represented by the following structural formula.

[0018]

Chemical formula

[0019] From the viewpoint of heat resistance, the PPS resin is preferably a polymer containing 70 mol% or more, more preferably 90 mol% or more of the repeating unit represented by the above structural formula. Further, the PPS resin may be composed of a repeating unit having a structure as follows, etc., with less than 30 mol% of its repeating unit.

[0020]

Chemical formula

[0021] Since the PPS copolymer having such a structure has a low melting point, such a resin composition is advantageous in terms of moldability.

[0022] The following describes a method for producing the PPS resin used in embodiments of the present invention, but the method is not limited to the following, as long as a PPS resin with the above structure can be obtained.

[0023] First, we will explain the polyhalogenated aromatic compounds, sulfidizing agents, polymerization solvents, molecular weight regulators, polymerization aids, and polymerization stabilizers used in the manufacturing process.

[0024] [Polyhalogenated aromatic compounds] Polyhalogenated aromatic compounds are compounds that have two or more halogen atoms in one molecule. Specific examples include 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, with p-dichlorobenzene being preferred. It is also possible to combine two or more different polyhalogenated aromatic compounds to form copolymers, but it is preferable to use a p-dihalogenated aromatic compound as the main component.

[0025] Regarding the amount of polyhalogenated aromatic compound used, from the viewpoint of obtaining a PPS resin with a viscosity suitable for processing, the lower limit can be 0.9 moles or more, preferably 0.95 moles or more, and more preferably 1.005 moles or more per mole of sulfidating agent, and the upper limit can be 2.0 moles or less, preferably 1.5 moles or less, and more preferably 1.2 moles or less per mole of sulfidating agent.

[0026] [Sulfide agents] Examples of sulfidating agents include alkali metal sulfides, alkali metal hydroxides, and hydrogen sulfide.

[0027] 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 particularly preferred. These alkali metal sulfides can be used as hydrates, aqueous mixtures, or in anhydrous form.

[0028] 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, with sodium hydroxide being particularly preferred. These alkali metal hydroxides can be used as hydrates, aqueous mixtures, or in anhydrous form.

[0029] Furthermore, alkali metal sulfides prepared in situ in the reaction system from alkali metal hydroxides and alkali metal hydroxides can also be used. Alternatively, alkali metal sulfides can be prepared from alkali metal hydroxides and alkali metal hydroxides and then transferred to a polymerization tank for use.

[0030] Alternatively, alkali metal sulfides prepared in situ in the reaction system from alkali metal hydroxides such as lithium hydroxide and sodium hydroxide and hydrogen sulfide can also be used. Furthermore, alkali metal sulfides can be prepared from alkali metal hydroxides such as lithium hydroxide and sodium hydroxide and hydrogen sulfide, and then transferred to a polymerization tank for use.

[0031] The amount of sulfidating agent used in the initial preparation shall refer to the remaining amount after deducting any loss of sulfidating agent due to dehydration or other processes before the polymerization reaction begins.

[0032] Furthermore, alkali metal hydroxides and / or alkaline earth metal hydroxides can be used in combination with the sulfidating agent. Specific examples of alkali metal hydroxides include, for example, sodium hydroxide, potassium hydroxide, lithium hydroxide, rubidium hydroxide, cesium hydroxide, and mixtures of two or more of these, which are preferred. Specific examples of alkaline earth metal hydroxides include, for example, calcium hydroxide, strontium hydroxide, and barium hydroxide, with sodium hydroxide being particularly preferred.

[0033] When using alkali metal hydroxide as a sulfidating agent, it is particularly preferable to use alkali metal hydroxide simultaneously. The amount of alkali metal hydroxide used is, for example, 0.95 moles or more, preferably 1.00 moles or more, and more preferably 1.005 moles or more per mole of alkali metal hydroxide, and 1.2 moles or less, preferably 1.15 moles or less, and more preferably 1.100 moles or less per mole of alkali metal hydroxide.

[0034] [Polymerization solvent] As the polymerization solvent, it is preferable to use an organic polar solvent. 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, hexamethylphosphate triamide, dimethyl sulfone, and tetramethylene sulfoxide, and mixtures thereof. All of these polymerization solvents are preferred because they offer high reaction stability. Among these, N-methyl-2-pyrrolidone (hereinafter sometimes abbreviated as "NMP") is particularly preferred.

[0035] The amount of organic polar solvent used is selected such that, per mole of sulfidating agent, the lower limit is 2.0 moles or more, preferably 2.25 moles or more, and the upper limit is 10 moles or less, preferably 6.0 moles or less, and the upper limit is 5.5 moles or less.

[0036] [Molecular weight regulator] Monohalogen compounds (not necessarily aromatic compounds) can be used in combination with the polyhalogenated aromatic compounds to form the ends of the PPS resin produced, or to adjust the polymerization reaction or molecular weight.

[0037] [Polymerization aid] To obtain a PPS resin with a relatively high degree of polymerization in a shorter time, it is also preferable to use polymerization aids. Here, "polymerization aid" refers to a substance that has the effect of increasing the viscosity of the obtained PPS resin. Specific examples of such polymerization aids include, for example, 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 individually or in combination of two or more. Among these, organic carboxylates, water, and alkali metal chlorides are preferred, with alkali metal carboxylates being preferred as organic carboxylates and lithium chloride being preferred as alkali metal chlorides.

[0038] The alkali metal carboxylates mentioned above are those with the general formula R(COOM) nThe compound is represented by the formula (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 from 1 to 3). Alkali metal carboxylates can also be used as hydrates, anhydrides, or aqueous solutions. Specific examples of alkali metal carboxylates include lithium acetate, sodium acetate, potassium acetate, sodium propionate, lithium valerate, sodium benzoate, sodium phenylacetate, potassium p-tolulate, and mixtures thereof.

[0039] Alkali metal carboxylates may be formed by 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 amounts. Among the above alkali metal carboxylates, lithium salts have high solubility in the reaction system and a large additive effect, but are expensive. On the other hand, potassium, rubidium, and cesium salts appear to have insufficient solubility in the reaction system. For this reason, sodium acetate, which is inexpensive and has moderate solubility in the polymerization system, is most preferably used.

[0040] When these alkali metal carboxylates are used as polymerization aids, the amount used is, at a lower limit, 0.01 moles or more, preferably 0.1 moles or more, and more preferably 0.2 moles or more, per mole of alkali metal sulfide added, and at an upper limit, 2 moles or less, preferably 0.6 moles or less, and more preferably 0.5 moles or less, in order to obtain a higher degree of polymerization.

[0041] Furthermore, when water is used as a polymerization aid, the amount added is, at a lower limit, 0.3 moles or more, preferably 0.6 moles or more, and more preferably 1 mole or more, per mole of alkali metal sulfide added. At an upper limit, 15 moles or less, preferably 10 moles or less, and more preferably 5 moles or less, to obtain a higher degree of polymerization.

[0042] It is certainly possible to use two or more of these polymerization aids in combination. For example, using an alkali metal carboxylate and water together allows for the production of high molecular weight PPS resin with smaller amounts of alkali metal carboxylate and water.

[0043] There are no specific timing requirements for adding these polymerization aids; they may be added during the pre-processing stage, at the start of polymerization, or during polymerization, as described later, and may also be added in multiple stages. When using alkali metal carboxylates as polymerization aids, it is preferable to add them simultaneously with other additives at the start of the pre-processing stage or at the start of polymerization, as this makes the addition easier. When using water as a polymerization aid, it is effective to add it during the polymerization reaction after charging the polyhalogenated aromatic compound.

[0044] [Polymerization stabilizer] Polymerization stabilizers can be used to stabilize the polymerization reaction system and prevent side reactions. Polymerization stabilizers contribute to the stabilization of the polymerization reaction system and suppress undesirable side reactions. One indicator of a side reaction is the formation of thiophenol. The formation of thiophenol can be suppressed by adding a polymerization stabilizer. 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 alkali metal carboxylates mentioned above also act as polymerization stabilizers and are therefore also included as polymerization stabilizers. Furthermore, as previously stated, when using alkali metal hydroxides as sulfidating agents, it is particularly preferable to use alkali metal hydroxides at the same time. In this case, excess alkali metal hydroxides relative to the sulfidating agent can also act as polymerization stabilizers.

[0045] These polymerization stabilizers can be used individually or in combination of two or more. The amount of polymerization stabilizer per mole of alkali metal sulfide used in the reaction mixture can be exemplified as follows: a lower limit of 0.02 moles or more, preferably 0.03 moles or more, and more preferably 0.04 moles or more; an upper limit of 0.2 moles or less, preferably 0.1 moles or less, and more preferably 0.09 moles or less. If the proportion is too low, the stabilization effect will be insufficient; conversely, if it is too high, it will be economically disadvantageous and tend to reduce the polymer yield.

[0046] There is no specific timing for adding the polymerization stabilizer; it can be added at any of the following stages: during the pre-processing stage, at the start of polymerization, or during polymerization. It can also be added in multiple stages. However, it is more preferable to add it simultaneously at the start of the pre-processing stage or at the start of polymerization, as this is easier.

[0047] Next, a preferred method for producing the PPS resin used in the embodiments of the present invention will be described in detail, step by step, including the pre-processing, polymerization reaction, recovery, and post-processing steps, but of course, the method is not limited to this method.

[0048] [Pre-process] In the method for producing PPS resin, sulfidating agents are usually used in hydrate form, but it is preferable to heat the mixture containing the organic polar solvent and the sulfidating agent before adding the polyhalogenated aromatic compound to remove excess water from the system.

[0049] Furthermore, as mentioned above, sulfidating agents prepared from alkali metal hydroxides and alkali metal hydroxides in situ within the reaction system or in a separate tank from the polymerization tank can also be used. There are no particular limitations to this method, but preferably, under an inert gas atmosphere, alkali metal hydroxides and alkali metal hydroxides are added to an organic polar solvent at a temperature range of room temperature to 150°C, preferably room temperature to 100°C, and the temperature is raised to at least 150°C, preferably 180 to 260°C, to remove the water by distillation. Polymerization aids may be added at this stage. In addition, toluene or the like may be added to accelerate the distillation of water.

[0050] In the polymerization reaction, the amount of water in the polymerization system is preferably 0.3 to 10.0 moles per mole of sulfidizing agent added. Here, "amount of water in the polymerization system" refers to the amount of water added to the polymerization system minus the amount of water removed from the polymerization system. The water added may be in any form, such as water, aqueous solution, or crystal water.

[0051] [Polymerization reaction process] PPS resin is produced by reacting a sulfidating agent and a polyhalogenated aromatic compound in an organic polar solvent at a temperature range of 200°C to less than 290°C.

[0052] To initiate the polymerization reaction, the organic polar solvent, sulfidating agent, and polyhalogenated aromatic compound are mixed, preferably under an inert gas atmosphere, at a lower limit of room temperature or higher, preferably 100°C or higher, and at an upper limit of 240°C or lower, preferably 230°C or lower. A polymerization aid may be added at this stage. The order in which these raw materials are added does not matter, and they can be added simultaneously.

[0053] This mixture is typically heated to a temperature in the range of 200°C to 290°C. There are no particular restrictions on the heating rate, but as a lower limit, a rate of 0.01°C / min or higher is selected, with a range of 0.1°C / min or higher being more preferable, and as an upper limit, a rate of 5°C / min or lower is selected, with a range of 3°C / min or lower being more preferable.

[0054] Generally, the temperature is eventually raised to 250-290°C, and the reaction is carried out at that temperature for a minimum of 0.25 hours, preferably 0.5 hours, and a maximum of 50 hours, preferably 20 hours.

[0055] A method that involves reacting the material at a temperature of, for example, 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 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 to be in the range of 0.25 to 20 hours, and preferably in the range of 0.25 to 10 hours.

[0056] Furthermore, in order to obtain polymers with a higher degree of polymerization, it may be effective to carry out polymerization in multiple steps. When carrying out polymerization in multiple steps, it is effective to proceed when the conversion rate of the polyhalogenated aromatic compound in the system at 245°C reaches 40 mol% or more, preferably 60 mol%.

[0057] The conversion rate of polyhalogenated aromatic compounds (abbreviated here as "PHA") is calculated using the following formula. The amount of remaining PHA can usually be determined by gas chromatography.

[0058] (a) When polyhalogenated aromatic compounds are added in excess in molar ratio relative to alkali metal sulfides Conversion rate = [Amount of PHA added (moles) - Amount of PHA remaining (moles)] / [Amount of PHA added (moles) - Excess PHA (moles)] (b) In cases other than (a) above Conversion rate = [Amount of PHA added (moles) - Amount of PHA remaining (moles)] / [Amount of PHA added (moles)].

[0059] [Recovery Process] In the method for producing PPS resin, after polymerization is complete, solid material is recovered from the polymerization reaction product, which includes the polymer and solvent. Any known method may be used for recovery.

[0060] For example, after the polymerization reaction is complete, a method of slowly cooling the polymer to recover the particulate polymer may be used. There are no particular restrictions on the slow cooling rate, but it is usually around 0.1°C / min to 3°C / min. It is not necessary to cool at the same rate throughout the entire slow cooling process; for example, a method of slow cooling at 0.1 to 1°C / min until the polymer particles crystallize and precipitate, and then at a rate of 1°C / min or higher may be adopted.

[0061] Furthermore, performing the above recovery under rapid cooling conditions is also a preferred method. Among these recovery methods, the flash method is a preferred method. The "flash method" involves applying high temperature and pressure (usually 250°C or higher, 8 kg / cm³) to the polymerization reaction product. 2 This method involves flashing the mixture from the above state into an atmosphere of normal or reduced pressure, recovering the solvent and simultaneously recovering the polymer in powder form. Here, "flash" means ejecting the polymerization reaction product from a nozzle. Specifically, the atmosphere used for flashing includes nitrogen or water vapor at normal pressure, and the temperature is usually selected in the range of 150°C to 250°C.

[0062] [Post-processing steps] The PPS resin may be produced through the polymerization and recovery process described above, and then subjected to acid treatment, hot water treatment, or cleaning with an organic solvent.

[0063] When performing acid treatment, the following procedures apply. The acid used for acid treatment of PPS resin is not particularly limited as long as it does not have the effect of decomposing the PPS resin, and examples include acetic acid, hydrochloric acid, sulfuric acid, phosphoric acid, silicic acid, carbonate, and propyl acid. Among these, acetic acid and hydrochloric acid are more preferably used.

[0064] Acid treatment methods include, for example, immersing the PPS resin in an acid or an aqueous solution of acid, and stirring or heating may be performed as needed. For example, when using acetic acid, sufficient effect can be obtained by immersing the PPS resin powder in an aqueous solution of acetic acid with a pH of 4 heated to 80-200°C and stirring for 30 minutes.

[0065] When performing hot water treatment, the following is required. When treating PPS resin with hot water, it is preferable to set the temperature of the hot water to 100°C or higher, more preferably 120°C or higher, even more preferably 150°C or higher, and particularly preferably 170°C or higher. Temperatures below 100°C are undesirable because the desired chemical modification effect on the PPS resin is small.

[0066] Furthermore, since the decomposition of end groups is undesirable, it is desirable to perform the treatment under an inert atmosphere to avoid this. In addition, to remove any remaining components, it is preferable to wash the PPS resin several times with warm water after this hot water treatment operation.

[0067] When cleaning with an organic solvent, the following applies. There are no particular restrictions on the organic solvent used to clean PPS resin, as long as it does not have the effect of decomposing the PPS resin. Examples of organic solvents used for cleaning PPS resins include nitrogen-containing polar solvents such as N-methyl-2-pyrrolidone, dimethylformamide, dimethylacetamide, 1,3-dimethylimidazolidinone, hexamethylphosphorusamide, and piperadinons; 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; halogen solvents such as chloroform, methylene chloride, trichloroethylene, dichloroethylene, perchloroethylene, monochloroethane, dichloroethane, tetrachloroethane, perchloroethane, and chlorobenzene; alcohol / phenol solvents such as methanol, ethanol, propanol, butanol, pentanol, ethylene glycol, propylene glycol, phenol, cresol, polyethylene glycol, and polypropylene glycol; and aromatic hydrocarbon solvents such as benzene, toluene, and xylene. Among these organic solvents, the use of N-methyl-2-pyrrolidone, acetone, dimethylformamide, and chloroform is particularly preferred. Furthermore, these organic solvents may be used individually or in combination of two or more.

[0068] One method of cleaning with organic solvents is to immerse the PPS resin in the organic solvent, and stirring or heating may be performed as needed. There are no particular restrictions on the cleaning temperature when cleaning PPS resin with organic solvents; any temperature from room temperature to approximately 300°C can be selected. Cleaning efficiency tends to increase with higher cleaning temperatures, but usually sufficient results can be obtained at cleaning temperatures from room temperature to 150°C. It is also possible to clean under pressure in a pressure vessel at a temperature above the boiling point of the organic solvent.

[0069] The post-treatment step preferably involves acid treatment, hot water treatment, or washing with an organic solvent, and using two or more of these treatments in combination is preferable from the viewpoint of removing impurities.

[0070] In embodiments of the present invention, PPS in which alkali metals or alkaline earth metals such as calcium have been introduced into PPS may be used. Methods for introducing alkali metals and alkaline earth metals include adding alkali metal salts and alkaline earth metal salts before, during, or after the above-mentioned preceding process; adding alkali metal salts and alkaline earth metal salts into the polymerization vessel before, during, or after the polymerization process; and adding alkali metal salts and alkaline earth metal salts at the first, intermediate, or final stage of the above-mentioned washing process.

[0071] PPS resin can also be used after its polymerization is complete by thermal oxidative crosslinking treatment, which involves heating in an oxygen atmosphere or heating with the addition of crosslinking agents such as peroxides, thereby increasing its molecular weight.

[0072] When dry heat treatment is performed for the purpose of increasing molecular weight by thermal oxidation crosslinking, the temperature is preferably 160°C or higher as a lower limit, more preferably 170°C or higher, and preferably 260°C or lower as an upper limit, more preferably 250°C or lower. Furthermore, it is desirable that the oxygen concentration be 5% by volume or higher, and more preferably 8% by volume or higher. 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 hours or higher as a lower limit, more preferably 1 hour or higher, even more preferably 2 hours or higher, and preferably 100 hours or lower as an upper limit, more preferably 50 hours or lower, and even more preferably 25 hours or lower. The heat treatment apparatus may be a normal hot air dryer or a rotary or agitator-equipped heating apparatus. For efficient and more uniform processing, it is preferable to use a rotary or agitator-equipped heating apparatus.

[0073] Furthermore, dry heat treatment is possible to suppress thermal oxidation crosslinking and remove volatile components. The temperature is preferably 130 to 250°C, and more preferably in the range of 160 to 250°C. In this case, the oxygen concentration is preferably less than 5% by volume, and more preferably less than 3% by volume. The treatment time is preferably 0.5 hours or more at the lower limit, more preferably 1 hour or more, and preferably 50 hours or less at the upper limit, more preferably 20 hours or less, and even more preferably 10 hours or less. The heat treatment apparatus may be a conventional hot air dryer or a rotary or agitator-equipped heating apparatus. For efficient and more uniform processing, it is more preferable to use a rotary or agitator-equipped heating apparatus.

[0074] From the viewpoint of improving fluidity during molding and toughness, it is preferable that the melt flow rate (MFR) of the PPS resin, measured at a temperature of 315.5°C and a load of 5000g, according to the method conforming to ASTM-D1238-70, is in the range of 80g / 10min to 6100g / 10min. Furthermore, a combination of multiple types of PPS resins with different MFRs may be used.

[0075] (B) Non-fibrous inorganic filler The PPS resin composition of the present invention requires the incorporation of (B) a non-fibrous inorganic filler having an aspect ratio of 5.0 or less. The aspect ratio of (B) the non-fibrous inorganic filler is preferably 1.0 or more and 4.0 or less, and more preferably 1.0 or more and 3.0 or less. The aspect ratio of the non-fibrous inorganic filler referred to here is the value calculated from the measured average diameter and average thickness as the aspect ratio (average diameter ÷ average thickness), as described below. When the aspect ratio of the non-fibrous inorganic filler is 5 or less, even when a certain amount or more of the non-fibrous inorganic filler is incorporated into the PPS resin, the thermal shock resistance of the PPS resin composition using a metal insert molded product can be made to 15 or more times (this refers to the number of times cracks occur in the weld area when a metal insert test piece with a hole in the center is subjected to thermal shock treatment (treatment at 130°C for 1 hour followed by treatment at -40°C for 1 hour). The same applies hereafter. The lower limit of the aspect ratio of the non-fibrous inorganic filler is substantially 1.0 or higher. Tracking resistance (referring to the value of the comparative tracking index measured in accordance with IEC60112 (2003); the same applies hereafter) and thermal shock resistance will be described later. The reason why the thermal shock resistance of metal insert molded products of PPS resin compositions can be set to 15 times or more by having the aspect ratio of the non-fibrous inorganic filler within the above range is presumed to be because when a non-fibrous inorganic filler with a small aspect ratio of 5.0 or less is used, the distance between the non-fibrous inorganic fillers in the resin composition increases, which greatly enhances the effect of utilizing the toughness of the resin itself.

[0076] (B) The average particle size of the non-fibrous inorganic filler is preferably 0.1 μm or more and 50.0 μm or less, more preferably 0.2 μm or more and 45.0 μm or less, and even more preferably 0.3 μm or more and 40.0 μm or less. When the average particle size of the non-fibrous inorganic filler is 0.1 μm or more, the thermal shock resistance of the PPS resin composition using metal insert molded products can be improved. The reason why high thermal shock resistance is exhibited in the above range is not clear, but it is presumed that in this range, the distance between the non-fibrous inorganic fillers in the resin composition is greater, so the effect of utilizing the toughness of the resin itself is greater. When the average particle size of the non-fibrous inorganic filler is 50.0 μm or less, the specific surface area of ​​the non-fibrous inorganic filler is large, so the tracking resistance of the PPS resin composition can be improved.

[0077] (B) One type of non-fibrous inorganic filler may be used, or two or more types may be used in combination.

[0078] The PPS resin composition of the present invention preferably contains (A) 100 parts by mass of PPS resin, with (B) a non-fibrous inorganic filler in an amount of 20 parts by mass to 170 parts by mass, more preferably 60 parts by mass to 170 parts by mass, and even more preferably 70 parts by mass to 160 parts by mass. When the amount of non-fibrous inorganic filler is 20 parts by mass or more, the tracking resistance of the PPS resin composition can be improved. When the amount of non-fibrous inorganic filler is 170 parts by mass or less, the thermal shock resistance of the PPS resin composition when used in a metal insert molded product can be improved.

[0079] (B) Specific examples of non-fibrous inorganic fillers include fullerene, talc, wollastonite, zeolite, sericite, mica, kaolin, clay, pyrophyllite, bentonite, asbestos, silicates such as alumina silicate, metal compounds such as silicon oxide, magnesium oxide, alumina, zirconium oxide, titanium oxide, and iron oxide, metal hydroxides such as magnesium hydroxide, aluminum hydroxide, and calcium hydroxide, carbonates such as calcium carbonate, magnesium carbonate, and dolomite, sulfates such as calcium sulfate and barium sulfate, glass beads, glass flakes, glass powder, ceramic beads, boron nitride, silicon carbide, carbon black, silica, and graphite. However, from the viewpoint of tracking resistance of the PPS resin composition, decomposition endothermic fillers that cause endothermic reactions during decomposition, such as magnesium hydroxide, magnesium carbonate, aluminum hydroxide, and calcium borate, and high thermal conductivity fillers are particularly preferred because they suppress the heat generation of the PPS resin composition and make it less likely for tracking to occur.

[0080] Furthermore, it is preferable to use non-fibrous inorganic fillers after surface treatment. Compounds used for surface treatment include vinylsilane compounds such as vinyltriethoxysilane and vinyltrichlorosilane, epoxysilane compounds such as γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, aminosilane compounds such as γ-(2-aminoethyl)aminopropylmethyldimethoxysilane, γ-(2-aminoethyl)aminopropyltrimethoxysilane, and γ-aminopropyltrimethoxysilane, γ-isocyanatopropyltriethoxysilane, and γ-isocyanatopropylmethyldi Examples include isocyanato group-containing alkoxysilane compounds such as methoxysilane, γ-isocyanatopropylmethyldiethoxysilane, γ-isocyanatopropylethyldimethoxysilane, γ-isocyanatopropylethyldiethoxysilane, and γ-isocyanatopropyltrichlorosilane; methacryloxysilane compounds such as 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, and 3-methacryloxypropyltriethoxysilane; and long-chain fatty acids or long-chain aliphatic alcohols such as stearic acid, oleic acid, montanic acid, and stearyl alcohol. In particular, the application of non-fibrous inorganic fillers surface-treated with vinylsilane compounds, epoxysilane compounds, aminosilane compounds, isocyanatosilane compounds, and methacryloxysilane compounds is preferred in terms of suppressing aggregation in compositions or molded articles, as well as in terms of tracking resistance and mechanical strength.

[0081] (C) Fibrous inorganic filler The PPS resin composition of the present invention preferably contains (C) a fibrous inorganic filler.

[0082] The PPS resin composition of the present invention preferably contains (A) 100 parts by mass of PPS resin and (C) 40 parts by mass or more and 190 parts by mass or less of fibrous inorganic filler. More preferably, it contains 70 parts by mass or more and 190 parts by mass or less, and even more preferably, 70 parts by mass or more and 160 parts by mass or less. When the amount of fibrous inorganic filler is 40 parts by mass or more, the thermal shock resistance of the PPS resin composition when used in a metal insert molded product can be improved. When the amount of fibrous inorganic filler is 190 parts by mass or less, the fluidity of the PPS resin composition during melting can be maintained.

[0083] (C)Specific examples of fibrous inorganic fillers include glass fibers, carbon fibers, carbon nanotubes, carbon nanohorns, potassium titanate whiskers, zinc oxide whiskers, calcium carbonate whiskers, wollastonite whiskers, aluminum borate whiskers, aramid fibers, alumina fibers, silicon carbide fibers, ceramic fibers, asbestos fibers, gypsum fibers, and metal fibers. The surface of the fibrous inorganic filler may also be pre-treated with coupling agents such as isocyanate compounds, organosilane compounds, organotitanate compounds, organoborane compounds, and epoxy compounds before use.

[0084] In particular, to obtain the effect of improving the rigidity of the material, it is preferable to select either glass fiber or carbon fiber, and from the viewpoint of material cost, glass fiber is more preferable. Furthermore, from the viewpoint of thermal shock resistance when using metal insert molded products of PPS resin composition, irregularly shaped cross-section glass fiber is preferred. Irregularly shaped cross-section glass fiber is a glass fiber having a flattened cross-section, and when the glass fiber is cut perpendicular to the length direction, the ratio of the major axis (longest straight distance of the cross-section) to the minor axis (longest straight distance perpendicular to the major axis) (hereinafter sometimes abbreviated as the irregularity ratio) is preferably 1.3 to 10.

[0085] (D) Elastomer The PPS resin composition of the present invention preferably contains (D) an elastomer. An elastomer refers to a material that has rubber elasticity, and examples include thermoplastic elastomers such as olefin-based (co)polymers and styrene-based (co)polymers, and thermosetting elastomers such as silicone elastomers and fluoroelastomers.

[0086] The PPS resin composition of the present invention preferably contains (A) elastomer in an amount of 1 to 40 parts by mass, more preferably 2 to 35 parts by mass, and even more preferably 5 to 30 parts by mass, per 100 parts by mass of PPS resin. When the amount of elastomer is 1 part by mass or more, the thermal shock resistance of the PPS resin composition when used in a metal insert molded product can be improved. When the amount of elastomer is 40 parts by mass or less, the flame retardancy of the PPS resin composition can be maintained.

[0087] (D) Preferably, an olefin copolymer having epoxy groups (D-1) is used as the elastomer. (A) Preferably, 1 to 40 parts by mass of the olefin copolymer having epoxy groups (D-1) is used per 100 parts by mass of PPS resin, and more preferably 2 to 35 parts by mass.

[0088] (D-1) Olefin copolymers having epoxy groups include (co)polymers obtained by polymerizing α-olefins alone or two or more, such as ethylene, propylene, 1-butene, 1-pentene, 1-octene, 4-methyl-1-pentene, and isobutylene; copolymers of α-olefins with α,β-unsaturated acids and their alkyl esters, such as acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, and butyl methacrylate; for example, ethylene / propylene copolymer (" / " represents copolymerization, the same applies hereinafter), ethylene / 1-butene copolymer, ethylene / 1-hexene, ethylene / 1-octene, ethylene / methyl acrylate copolymer, ethylene / ethyl acrylate copolymer, ethylene / butyl acrylate copolymer, ethylene / methyl methacrylate copolymer, ethylene / ethyl methacrylate copolymer, and ethylene / butyl methacrylate copolymer, etc., by introducing monomer components (functional group-containing components) having epoxy groups. Examples of functional group-containing components include monomers containing epoxy groups such as glycidyl acrylate, glycidyl methacrylate, glycidyl ethacrylate, glycidyl itaconic acid, and glycidyl citraconic acid. There are no particular restrictions on the method of introducing these functional group-containing components; methods such as copolymerization during the copolymerization of olefin-based (co)polymers or graft introduction into olefin-based (co)polymers using radical initiators can be used. Particularly useful examples of epoxy-group-containing olefin copolymers obtained by introducing functional group-containing components into olefin-based (co)polymers include ethylene / propylene-g-glycidyl methacrylate copolymer ("g" represents a graft, the same applies hereafter), ethylene / 1-butene-g-glycidyl methacrylate copolymer, ethylene / glycidyl acrylate copolymer, ethylene / glycidyl methacrylate copolymer, ethylene / methyl acrylate / glycidyl methacrylate copolymer, and ethylene / methyl methacrylate / glycidyl methacrylate copolymer. Alternatively, epoxy group-containing olefin copolymers, which include α-olefins such as ethylene and propylene, glycidyl esters of α,β-unsaturated acids, and other monomers as essential components, are also suitably used.

[0089] In particular, from the viewpoint of thermal shock resistance, olefin copolymers containing structures derived from glycidyl esters of α,β-unsaturated acids are preferred, and ethylene / methyl acrylate / glycidyl methacrylate copolymers are even more preferred. From the viewpoint of thermal shock resistance, the lower limit of the content of constituent units derived from glycidyl esters of α,β-unsaturated acids is preferably 0.01 parts by mass or more, and more preferably 0.03 parts by mass or more, when the total resin composition is 100 parts by mass. From the viewpoint of fluidity during melting, the upper limit of the content of constituent units derived from glycidyl esters of α,β-unsaturated acids is preferably less than 0.15 parts by mass, and more preferably 0.10 parts by mass or less, when the total resin composition is 100 parts by mass.

[0090] Furthermore, in the present invention, it is also preferable to blend (D-2) an elastomer without epoxy groups as (D) elastomer. It is preferable to blend 1 to 40 parts by mass of (D-2) an elastomer without epoxy groups with 100 parts by mass of (A) PPS resin, and more preferably 2 to 35 parts by mass.

[0091] (D) As the elastomer, it is preferable to use a combination of (D-1) an olefin copolymer having epoxy groups and (D-2) an elastomer without epoxy groups. From the viewpoint of resistance to thermal shock, specific examples of elastomers without epoxy groups include elastomers having at least one functional group selected from the group consisting of carboxyl groups, acid anhydride groups, hydroxyl groups, amino groups, epoxy groups, and isocyanate groups, or elastomers that do not have polar functional groups in particular. Furthermore, any elastomer without epoxy groups may be a thermoplastic elastomer such as an olefin (co)polymer or a styrene (co)polymer. Alternatively, it may be a thermosetting elastomer such as a silicone elastomer or a fluoroelastomer.

[0092] (D-2) For elastomers that do not have epoxy groups, from the viewpoint of thermal shock resistance when used in metal insert molded products, the glass transition temperature is preferably -20°C or lower, and more preferably -30°C or lower.

[0093] (E) Silicone compounds In the PPS resin composition used in the present invention, it is preferable to add (E) silicone compounds from the viewpoint of tracking resistance and thermal shock resistance when using metal insert molded articles. Silicone compounds are organosilicon compounds that have a siloxane bond as a backbone and in which organic groups are directly bonded to the silicon. Known organic groups directly bonded to silicon include methyl groups, ethyl groups, phenyl groups, vinyl groups, trifluoropropyl groups, and combinations thereof, but these known silicone compounds can be used without particular limitation. In addition, silicone compounds in which some of the organic groups are substituted with substituents having epoxy groups, amino groups, polyether groups, carboxyl groups, mercapto groups, ester groups, chloroalkyl groups, alkyl groups having 3 or more carbon atoms, hydroxyl groups, etc. can also be used. Silicone compounds are classified into silicone oils, silicone elastomers, and silicone resins depending on the degree of crosslinking. Although silicone elastomers also fall under (D) elastomers, they are treated as (E) silicone compounds in the present invention. While any of the silicone compounds can be used, silica powder supported with silicone oil and silicone elastomers with a high degree of crosslinking that are less prone to decomposition are particularly preferred from the viewpoint of workability, tracking resistance, thermal shock resistance, and strength. Furthermore, finely powdered silicone compounds with an average particle size of 0.1 to 80 μm are effective because they have good dispersibility and excellent workability.

[0094] The amount of the (E) silicone compound blended is preferably 0.1 to 20 parts by mass, and more preferably 0.1 to 15 parts by mass, per 100 parts by mass of PPS resin. An amount of 0.1 parts by mass or more is preferable from the viewpoint of improving tracking resistance and thermal shock resistance when using metal insert molded products. An amount of 20 parts by mass or less is preferable from the viewpoint of maintaining the mechanical strength of the resin composition and reducing gas generation.

[0095] (F) Organosilane compounds The PPS resin composition used in the present invention may contain an (F) organosilane compound having at least one functional group selected from epoxy groups, amino groups, isocyanate groups, hydroxyl groups, mercapto groups, and ureido groups, to improve mechanical strength, toughness, etc., to the extent that it does not impair the effects of the present invention. Specific examples of such compounds include epoxy group-containing alkoxysilane compounds such as γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; mercapto group-containing alkoxysilane compounds such as γ-mercaptopropyltrimethoxysilane and γ-mercaptopropyltriethoxysilane; ureido group-containing alkoxysilane compounds such as γ-ureidopropyltriethoxysilane, γ-ureidopropyltrimethoxysilane, and γ-(2-ureidoethyl)aminopropyltrimethoxysilane; γ-isocyanatetopropyltriethoxysilane, γ-isocyanatetopropyltrimethoxysilane, and γ-isocyanatetopropyl Examples include isocyanate group-containing alkoxysilane compounds such as pyrmethyldimethoxysilane, γ-isocyanatetopropylmethyldiethoxysilane, γ-isocyanatetopropylethyldimethoxysilane, γ-isocyanatetopropylethyldiethoxysilane, and γ-isocyanatetopropyltrichlorosilane; amino group-containing alkoxysilane compounds such as γ-(2-aminoethyl)aminopropylmethyldimethoxysilane, γ-(2-aminoethyl)aminopropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, and γ-aminopropyltriethoxysilane; and hydroxyl group-containing alkoxysilane compounds such as γ-hydroxypropyltrimethoxysilane and γ-hydroxypropyltriethoxysilane. In particular, alkoxysilane compounds having at least one functional group selected from epoxy groups, amino groups, isocyanate groups, and hydroxyl groups are especially suitable for obtaining excellent tracking resistance, thermal shock resistance, and weld strength because they can improve the dispersibility of (B) non-fibrous inorganic fillers and (D) elastomers in the PPS resin composition, and increase the interfacial strength between (B) non-fibrous inorganic fillers and (C) fibrous inorganic fillers and the PPS resin.The preferred amount of such (F) organosilane compound to be added is preferably in the range of 0.05 to 5 parts by mass per 100 parts by mass of PPS resin.

[0096] (G) Other resins The PPS resin composition used in the present invention may be blended with (G) other resins, to the extent that the effects of the present invention are not impaired. There are no particular restrictions on the blendable resins, but specific examples include polyester resins such as polyamide, polyethylene terephthalate, polybutylene terephthalate, polycyclohexyldimethylene terephthalate, and polynaphthalene terephthalate, polyethylene, polypropylene, polytetrafluoroethylene, polyamide-imide, polyacetal, polyimide, polyetherimide, polyethersulfone, polysulfone resin, polyallylsulfone resin, polyketone resin, polyarylate resin, liquid crystal polymer, polyetherketone resin, polythioetherketone resin, polyetheretherketone resin, and polyamide-imide resin.

[0097] The PPS resin composition of the present invention may contain other components, to the extent that it does not impair the effects of the present invention, such as antioxidants and heat stabilizers (hindered phenol, hydroquinone, phosphorus, phosphite, amine, sulfur, and their substituted derivatives, etc.), weathering agents (resorcinol, salicylate, benzotriazole, benzophenone, hindered amine, etc.), mold release agents and lubricants (montanic acid and its metal salts, its esters, its half-esters, stearyl alcohol, stearamide, stearat, bisurea, and polyethylene wax, etc.), pigments (cadmium sulfide, phthalocyanine, carbon black for coloring, etc.), dyes (nigrosine, etc.), plasticizers (octyl p-oxybenzoate, N-butylbenzenesulfonamide, etc.), antistatic agents (alkyl sulfate type anionic antistatic agents, quaternary ammonium salt type cationic antistatic agents, polyoxyethylene sorbitan mono Conventional additives such as nonionic antistatic agents like stearate, betaine-based amphoteric antistatic agents, etc., flame retardants (e.g., red phosphorus, phosphate esters, melamine cyanurate, ammonium polyphosphate, brominated polystyrene, brominated polyphenylene ether, brominated polycarbonate, brominated epoxy resin, or combinations of these brominated flame retardants with antimony trioxide, etc.), heat stabilizers, lubricants such as calcium stearate, aluminum stearate, lithium stearate, strength improvers such as bisphenol epoxy resins such as bisphenol A type, novolac phenol type epoxy resin, cresol novolac type epoxy resin, UV inhibitors, colorants, flame retardants, and foaming agents can be added, and it is preferable to use antioxidants and heat stabilizers (hindered phenol type, hydroquinone type, phosphorus type, phosphite type, amine type, sulfur type, and their substituted products, etc.). More preferably, phosphorus-based antioxidants and hindered phenol-based antioxidants are used. Since any of the above compounds may impair the inherent properties of the PPS resin if added in amounts exceeding 20% ​​by mass of the total composition, it is even more preferable to add them at an amount of 10% by mass or less.

[0098] There are no particular limitations on the method for preparing the PPS resin composition of the present invention, but typical examples include supplying each raw material to a commonly known melt mixer such as a single-screw or twin-screw extruder, a Banbury mixer, a kneader, and a mixing roll, and kneading them at a temperature of 280 to 380°C. There are no particular limitations on the mixing order of the raw materials, 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 method; a method in which some raw materials are blended and then melt-kneaded by the above method, and then the remaining raw materials are blended and melt-kneaded again; or a method in which some raw materials are blended and then the remaining raw materials are mixed using a side feeder while melt-kneading is performed with a single-screw or twin-screw extruder. Furthermore, for small amounts of additive components, it is also possible to knead other components by the above method or other methods to form pellets, and then add them before molding.

[0099] The PPS resin composition obtained in this manner can be used in various molding processes such as injection molding, extrusion molding, blow molding, and transfer molding, but is particularly suitable for injection molding.

[0100] The PPS resin composition of the present invention preferably has a tensile elongation of 1.0% or more. This makes it suitable for use in parts where deformation is expected during use, such as snap-fit ​​shapes. Furthermore, a tensile elongation of 1.0% or more improves the thermal shock resistance when using metal insert molded products. The tensile elongation in this invention is a value measured in accordance with ISO 527-1,-2 (2012).

[0101] The tracking resistance of the PPS resin composition of the present invention is evaluated by the value of the comparative tracking index measured in accordance with IEC 60112 (2003). A higher comparative tracking index indicates higher tracking resistance.

[0102] The PPS resin composition of the present invention preferably has a tracking resistance of 300V or higher, more preferably 350V or higher, and even more preferably 400V or higher, as measured in accordance with IEC60112 (2003). This makes tracking failure less likely to occur when the PPS resin composition of the present invention is used in components to which high voltage (400V or higher) is applied, thereby improving the safety of the molded product. Furthermore, it becomes possible to ensure a creepage distance of the molded product that is greater than or equal to the required creepage distance specified in IEC60664. Therefore, molded products made from the PPS resin composition of the present invention have improved design flexibility and make it easier to achieve miniaturization and weight reduction of the molded product. If the tracking resistance of the PPS resin composition is less than 300V, tracking failure may easily occur on the surface of the molded product made from the PPS resin composition, making it unsafe to use in components to which high voltage is applied.

[0103] The PPS resin composition of the present invention must have a thermal shock resistance of 15 or more cycles when used in metal insert molded articles, preferably 20 or more cycles. This ensures that when the PPS resin composition of the present invention is used in metal insert molded articles, cracking of the molded article is less likely to occur, allowing for suitable use. If the thermal shock resistance of the PPS resin composition is less than 15 cycles, when a metal insert molded article made of the PPS resin composition is used in a location where the ambient temperature fluctuates (approximately -40°C to 130°C), resin cracking may occur. In this invention, thermal shock resistance is evaluated by the number of treatments required to cause cracks in the weld area when a metal insert test piece with a weld area intentionally created by providing a hole in the center, as shown in Figure 1, is subjected to thermal shock treatment. The number of treatments required to cause cracks represents the crack resistance of the weld area, and a higher number of treatments indicates higher thermal shock resistance. The weld area is prone to cracking due to its weak mechanical strength caused by the orientation of the fibrous inorganic filler, but if the thermal shock resistance of the weld area of ​​the PPS resin composition is high, it can be applied to metal insert molded articles of various shapes. For example, it can be suitably used in automotive electrical components such as current sensors and busbars, and in electrical and electronic components such as power semiconductor housings. These components can be suitably mounted in eAxles and xEVs. An eAxle is an integrated motor, inverter, and reduction gear used in the drive system of electric vehicles. xEV is a general term for electric vehicles, including battery electric vehicles (BEVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and fuel cell electric vehicles (FCEVs).

[0104] Applicable applications of the PPS resin composition of the present invention include, for example, electrical and electronic components such as power semiconductor housings like power modules, sensors, consumer connectors, relay cases, coil bobbins, capacitors, various terminal boards, insulating boards, and small motors; and various automotive and vehicle-related parts such as distributors, starter switches, starter relays, transmission wire harnesses, fuel-related solenoid valve coils, fuse connectors, electrical component insulating boards, terminal blocks, stepper motor rotors, solenoid bobbins, engine oil filters, ignition device cases, vehicle speed sensors, current sensors, busbars, capacitor cases, and cable liners, as well as various automotive electrical components. [Examples]

[0105] The present invention will be further described with reference to the following examples, but the present invention is not limited to the descriptions in these examples.

[0106] [Evaluation method for PPS resin manufactured using the example] (1) Melt Flow Rate (MFR) The measurement was performed at a temperature of 315.5°C and under a load of 5000g, following the method compliant with ASTM-D1238-70.

[0107] However, for low-viscosity polyphenylene sulfide resins, the MFR was calculated using the following method. The polyphenylene sulfide resin was measured at a temperature of 315.5°C and under a 345g load, and the ER was measured according to the method conforming to ASTM-D1238-70. The MFR value was then calculated using the following formula. MFR = 15.8 × 4.4 × ER.

[0108] [Reference example 1] In a 70-liter autoclave equipped with a stirrer and bottom valve, 8.27 kg (70.00 mol) of 47.5% sodium hydrosulfide, 2.91 kg (69.80 mol) of 96% sodium hydroxide, 11.45 kg (115.50 mol) of N-methyl-2-pyrrolidone (NMP), and 10.5 kg of deionized water were charged. The mixture was gradually heated to 245°C over approximately 3 hours under atmospheric pressure while passing nitrogen through it. After distilling off 14.78 kg of water and 0.28 kg of NMP, the reaction vessel was cooled to 200°C. The amount of residual water in the system per mole of alkali metal sulfide was 1.06 moles, including the water consumed in the hydrolysis of NMP. The amount of hydrogen sulfide released was 0.02 moles per mole of alkali metal sulfide.

[0109] The mixture was then cooled to 200°C, and 10.48 kg (71.27 mol) of p-dichlorobenzene and 9.37 kg (94.50 mol) of NMP were added. The reaction vessel was sealed under nitrogen gas, and the temperature was raised from 200°C to 270°C at a rate of 0.6°C / min while stirring at 240 rpm. After reacting at 270°C for 100 minutes, the bottom valve of the autoclave was opened, and the contents were flushed into a stirrer-equipped container over 15 minutes under pressurized nitrogen. The mixture was then stirred at 250°C for a while to remove most of the NMP.

[0110] The obtained solid material and 76 liters of deionized water were placed in an autoclave with a stirrer, washed at 70°C for 30 minutes, and then filtered by suction using a glass filter. Next, 76 liters of deionized water heated to 70°C were poured into the glass filter and filtered by suction to obtain the cake.

[0111] The resulting cake and 90 liters of deionized water were placed in an autoclave equipped with a stirrer, and acetic acid was added to bring the pH to 7. After purging the inside of the autoclave with nitrogen, the temperature was raised to 192°C and held for 30 minutes. The autoclave was then cooled and the contents were removed.

[0112] The contents were filtered by suction using a glass filter, and then 76 liters of ion-exchanged water at 70°C were poured in and filtered by suction to obtain a cake. The obtained cake was dried under a nitrogen stream at 120°C to obtain dried PPS.

[0113] The obtained PPS resin was subjected to thermal oxidation treatment at an oxygen concentration of 2%, 220°C, and for 12 hours. The resulting PPS had an ER of 67 g / 10 min, which, when converted to MFR, was 4658 g / 10 min.

[0114] [Reference example 2] In a 70-liter autoclave equipped with a stirrer and bottom valve, 8.27 kg (70.00 mol) of 47.5% sodium hydrosulfide, 2.94 kg (70.63 mol) of 96% sodium hydroxide, 11.45 kg (115.50 mol) of N-methyl-2-pyrrolidone (NMP), 0.513 kg (6.25 mol) of sodium acetate, and 3.82 kg of deionized water were charged. The mixture was gradually heated to 245°C over approximately 3 hours under atmospheric pressure while passing nitrogen through it. After distilling off 8.09 kg of water and 0.28 kg of NMP, the reaction vessel was cooled to 200°C. The amount of residual water in the system per mole of alkali metal sulfide charged was 1.06 mol, including the water consumed in the hydrolysis of NMP. The amount of hydrogen sulfide released was 0.02 mol per mole of alkali metal sulfide charged.

[0115] The mixture was then cooled to 200°C, and 10.34 kg (70.32 mol) of p-dichlorobenzene and 9.37 kg (94.50 mol) of NMP were added. The reaction vessel was sealed under nitrogen gas, and the temperature was raised from 200°C to 270°C at a rate of 0.6°C / min while stirring at 240 rpm. The reaction was then carried out at 270°C for 140 minutes. Subsequently, 2.67 kg (148.4 mol) of water was injected under pressure while the mixture cooled from 270°C to 250°C over 15 minutes. After that, the mixture was gradually cooled from 250°C to 220°C over 75 minutes, then rapidly cooled to near room temperature, and the contents were removed.

[0116] The contents were diluted with approximately 35 liters of NMP to form a slurry, which was stirred at 85°C for 30 minutes. The slurry was then filtered through an 80-mesh wire mesh (mesh opening 0.175 mm) to obtain solid material. The obtained solid material was similarly washed and filtered with approximately 35 liters of NMP. The obtained solid material was diluted with 70 liters of deionized water, stirred at 70°C for 30 minutes, and filtered through an 80-mesh wire mesh to recover the solid material. This process was repeated a total of three times. The obtained solid material and 32 g of acetic acid were diluted with 70 liters of deionized water, stirred at 70°C for 30 minutes, and filtered through an 80-mesh wire mesh. The obtained solid material was then diluted with 70 liters of deionized water, stirred at 70°C for 30 minutes, and filtered through an 80-mesh wire mesh to recover the solid material. The solid material thus obtained was dried under a nitrogen atmosphere at 120°C to obtain dried PPS. The obtained PPS had an MFR of 600 g / 10 min.

[0117] The raw materials used in the examples and comparative examples are shown below.

[0118] (A)PPS resin PPS-1: PPS resin polymerized by the method described in Reference Example 1 PPS-2: PPS resin polymerized by the method described in Reference Example 2.

[0119] (B) Non-fibrous inorganic filler B-1: Surface-treated magnesium hydroxide (manufactured by Kamishima Chemical Industry Co., Ltd., "Magsees" (registered trademark) V-4, vinyl sisilane treated) B-2: Surface-treated magnesium hydroxide (Kamishima Chemical Industry Co., Ltd. "Magsees" (registered trademark) EP1, vinylsilane treated product) B-3: Surface-treated magnesium hydroxide (Kamishima Chemical Industry Co., Ltd. "Magsees" (registered trademark) V-6, vinylsilane treatment) B-4: Surface-treated magnesium hydroxide (Kyowa Chemical Industry Co., Ltd. "KISUMA" (registered trademark) 5P, methacryloxysilane treatment) B-5: Surface-treated magnesium hydroxide (Kyowa Chemical Industry Co., Ltd. "KISUMA" (registered trademark) 8SN, treated with a special silane coupling agent).

[0120] (C) Fibrous inorganic filler C-1: Chopped strand (Nitto Boshoku Co., Ltd. CSG 3PA 830 S, 3 mm length, short axis 7 μm, long axis 28 μm, irregularity ratio 4.0) C-2: Chopped strand (manufactured by Nippon Electric Glass Co., Ltd., T-760H, 3mm length, average fiber diameter 10.5μm, shape ratio 1.0) C-3: Chopped strand (manufactured by Nippon Electric Glass Co., Ltd., T-760FGF, 3mm length, short diameter 7μm, long diameter 28μm, shape ratio 4.0).

[0121] (D) Elastomer D-1: Ethylene-glycidyl methacrylate-methyl acrylate copolymer (Sumitomo Chemical Co., Ltd. "Bondfast" (registered trademark) 7M, ethylene 67% by mass, glycidyl methacrylate 6% by mass, methyl acrylate 27% by mass) D-2: Ethylene-1-octene copolymer (Engage® 8842, manufactured by The Dow Chemical Company, glass transition temperature -61°C).

[0122] (E) Silicone compounds E-1: Dimethyl silicone oil-supported silica powder (Dow-Toray Industries, Ltd. "Dowsil" (registered trademark) Trefil F-202) E-2: Silicone elastomer powder (Dowsil EP-2601, epoxy modified, manufactured by Dow-Toray Corporation).

[0123] (F) Organosilane compounds F-1: β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane (KBM-303, manufactured by Shin-Etsu Chemical Co., Ltd.).

[0124] (G) Other resins G-1: Nylon 610 (Toray Industries, Inc., CM2021).

[0125] The evaluation and measurement methods used in the examples and comparative examples are shown below.

[0126] [Aspect ratio of non-fibrous inorganic fillers] Double-sided tape was attached to the sample stage, and a non-fibrous inorganic filler was applied over it using a spatula. After platinum deposition, a 5000x magnification image was taken using a Hitachi High-Tech scanning electron microscope (SU8220). Using image analysis software (ImageJ), 50 particles were randomly selected from the captured image, and the average value of the longest particle diameter (average diameter) and average thickness were determined. From the obtained average diameter and average thickness, the aspect ratio was calculated using the following formula. Aspect ratio = average diameter ÷ average thickness.

[0127] [Average particle size of non-fibrous inorganic fillers] 20 mg of non-fibrous inorganic filler was placed in 5 mL of 0.2 w / v% sodium hexametaphosphate aqueous solution and dispersed in an ultrasonic cleaner for 3 minutes. The particle size distribution of the resulting dispersion was measured using a particle size distribution analyzer (SALD-2100) manufactured by Shimadzu Corporation, and the volume-average particle diameter was calculated.

[0128] [Tracking resistance] Using a Sumitomo Heavy Industries, Ltd. injection molding machine (SE50DUZ-C160), a rectangular plate (80mm x 80mm x 3.0mm thick) was molded under the conditions of a cylinder temperature of 320°C and a mold temperature of 130°C. The maximum voltage at which tracking failure does not occur was determined in accordance with IEC 60112, 4th edition. A 0.1% aqueous ammonium chloride solution was used as the electrolyte.

[0129] [Resistance to thermal shock] A metal insert test specimen, as shown in Figure 1, was molded using a Sumitomo Heavy Industries, Ltd. injection molding machine (SE30D). A cassette-shaped metal (SUS430) measuring 50mm x 35mm x 5mm with two holes in the center was placed in the mold. The specimen was molded under the following conditions: injection speed of 70mm / s, injection pressure for a filling time of 0.5s, holding pressure of 0.6 times the injection pressure for 5s, cylinder temperature of 320°C, and mold temperature of 130°C. The metal insert molded product was subjected to thermal shock treatment, with each cycle consisting of treatment at 130°C for 1 hour followed by treatment at -40°C for 1 hour. The presence or absence of cracks was visually inspected every 10 cycles, and the average value for N=3 was calculated. This test specimen intentionally created a weld area by providing holes in the center, and its thermal shock resistance was simulated.

[0130] [Tensile strength, tensile elongation] Using a Sumitomo Heavy Industries injection molding machine (SE75DUZ-C250), a Type A1 test specimen as defined in ISO 20753 (2008) was molded under conditions of a resin temperature of 310°C and a mold temperature of 140°C. Tensile strength and tensile elongation (breaking point) were measured in accordance with ISO 527-1,2 under conditions of a support distance of 114 mm and a tensile speed of 5 mm / min.

[0131] [Examples 1-3, Comparative Examples 1-4] Using a TEX30α twin-screw extruder manufactured by Japan Steel Works Ltd., with the cylinder temperature set to 300°C and the screw rotation speed to 200 rpm, 100 parts by mass of (A) PPS resin obtained in Reference Examples 1 and 2 were mixed with (B) non-fibrous inorganic filler, (D) elastomer, (E) silicone compound, (F) organic silane compound, and (G) other resin in the mass ratios shown in Table 1, and (C) fibrous inorganic filler was added from the side feeder of the twin-screw extruder in the mass ratios shown in Table 1. The resin discharged from the extruder was pelletized in a pulverizer, then hot-air dried overnight at 120°C, and subjected to injection molding, and various molding and evaluation processes were performed.

[0132] Examples 1-3 showed that by setting the aspect ratio of the particle size distribution of (B) non-fibrous inorganic filler within a predetermined range, both tracking resistance and thermal shock resistance when using metal insert molded products were achieved. The PPS resin composition of these examples can be safely used in molded products subjected to high voltage, such as automotive parts and electrical / electronic components, as well as in metal insert molded products.

[0133] Comparative Example 1 was found to have poor resistance to thermal shock due to the large aspect ratio of (B) non-fibrous inorganic filler.

[0134] Comparative Example 2 was found to have poor thermal shock resistance because (B) the non-fibrous inorganic filler had a large aspect ratio.

[0135] Comparative Example 3 was found to have poor thermal shock resistance because (B) the aspect ratio of the non-fibrous inorganic filler was large and (C) the fibrous inorganic filler was not a glass with an irregular cross-section.

[0136] Comparative Example 4 was found to have poor thermal shock resistance because (B) the aspect ratio of the non-fibrous inorganic filler was large and (D) it did not contain an elastomer.

[0137] [Table 1] [Explanation of symbols]

[0138] 1. Insert metal 2. Gate 3. Metal insert molded product

Claims

1. A polyphenylene sulfide resin composition comprising (A) a polyphenylene sulfide resin and (B) a non-fibrous inorganic filler having an aspect ratio of 5.0 or less, wherein when a metal insert test piece with a hole in the center to intentionally create a weld area is subjected to thermal shock treatment (treatment at 130°C for 1 hour followed by treatment at -40°C for 1 hour), the number of treatments required for cracks to occur in the weld area is 15 or more.

2. (B) The polyphenylene sulfide resin composition according to claim 1, wherein the average particle size of the non-fibrous inorganic filler is 0.1 μm or more and 50.0 μm or less.

3. A polyphenylene sulfide resin composition according to claim 1 or 2, comprising (A) 100 parts by mass of polyphenylene sulfide resin and (B) 20 parts by mass or more and 170 parts by mass or less of a non-fibrous inorganic filler.

4. The polyphenylene sulfide resin composition according to claim 3, wherein the (B) non-fibrous inorganic filler is a decomposition endothermic filler.

5. A polyphenylene sulfide resin composition according to claim 1 or 2, comprising (A) 100 parts by mass of polyphenylene sulfide resin and (C) 40 parts by mass or more and 190 parts by mass or less of fibrous inorganic filler.

6. (C) The polyphenylene sulfide resin composition according to claim 5, wherein the fibrous inorganic filler is a glass fiber with a shape ratio of 1.3 or more and 10 or less.

7. The polyphenylene sulfide resin composition according to claim 1 or 2, comprising (A) 100 parts by mass of polyphenylene sulfide resin and (D) 1 to 40 parts by mass of elastomer.

8. The polyphenylene sulfide resin composition according to claim 1 or 2, wherein the comparative tracking index value measured in accordance with IEC 60112 (2003) is 300V or higher.

9. A molded article comprising the polyphenylene sulfide resin composition according to claim 1 or 2.

10. An automotive electrical component comprising the polyphenylene sulfide resin composition according to claim 1 or 2.

11. A current sensor comprising the polyphenylene sulfide resin composition according to claim 1 or 2.

12. A bus bar comprising the polyphenylene sulfide resin composition according to claim 1 or 2.

13. A power semiconductor housing comprising the polyphenylene sulfide resin composition according to claim 1 or 2.

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