Polyphenylene sulfide resin composition and molded article

Abstract

To provide a polyphenylene sulfide resin composition which is excellent in cold thermal shock resistance and tracking resistance without greatly impairing excellent mechanical strength and flame retardancy inherent in a polyphenylene sulfide resin, and a molded article of the same.SOLUTION: A polyphenylene sulfide resin composition is obtained by blending 60 pts.wt. or more and 150 pts.wt. or less of (B) a modified cross-section glass fiber, 50 pts.wt. or more and 140 pts.wt. or less of (C) a non-fibrous inorganic filler, and 1 pts.wt. or more and less than 15 pts.wt. of (D) an elastomer, with respect to 100 pts.wt. of (A) a polyphenylene sulfide resin, wherein (D) the elastomer contains an olefinic copolymer having (D-1) an epoxy group.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a polyphenylene sulfide resin composition excellent in cold and heat shock resistance and tracking resistance without significantly impairing the excellent mechanical strength and flame retardancy inherent in polyphenylene sulfide resin, and a molded product thereof.

Background Art

[0002] Polyphenylene sulfide (hereinafter sometimes abbreviated as PPS) resin is excellent in heat resistance, flame retardancy, chemical resistance, electrical insulation, heat and humidity resistance, mechanical strength, and dimensional stability, and is therefore widely used in electrical and electronic parts, mechanical parts, and automotive parts.

[0003] In recent years, with the electrification of automobiles, the mounting of resin molded products with metal inserts, such as bus bars, in automobiles has increased significantly. Since the usage environment of automobiles is diverse, a resin composition excellent in cold and heat shock resistance, which does not cause cracking of the metal insert molded product even when the environmental temperature changes greatly, is required.

[0004] In addition, automotive parts are required to be thinner for weight reduction purposes. Generally, the thinner the resin molded product, the more likely its mechanical strength and flame retardancy are to decrease, and a resin composition with improved these properties is required.

[0005] Furthermore, as electric vehicles have higher output, the rated voltage tends to increase. Therefore, a resin molded product that can withstand tracking breakdown that occurs when a high voltage is applied to the surface of an insulator is required.

[0006] Because PPS resin has inferior thermal shock resistance compared to other engineering plastics, Patent Document 1 describes a resin composition comprising PPS resin, a reactive olefin copolymer containing an acrylic acid ester, an unmodified olefin copolymer containing butyl acrylate, and an inorganic filler. Patent Document 2 also describes a resin composition comprising PPS resin, a fibrous inorganic filler and a non-fibrous inorganic filler, and an olefin copolymer, all of which have a cross-sectional ratio of 3.0 or more, where the ratio of the major axis to the minor axis of the cross-section perpendicular to the longitudinal direction is 3.0 or more.

[0007] Furthermore, since PPS resin has inferior tracking resistance compared to other engineering plastics such as polyamide resin and polyester resin, Patent Document 3 describes a resin composition that achieves both tracking resistance and high / low temperature impact resistance by incorporating predetermined amounts of inorganic fillers and olefin copolymers into the PPS resin. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2017-155221 [Patent Document 2] Patent Application No. 2020-109135 [Patent Document 3] Japanese Patent Publication No. 2020-105502 [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] However, although the resin composition disclosed in Patent Document 1 has improved resistance to thermal shock, it has low tracking resistance, and although there is no specific description regarding flame retardancy, it is considered to have insufficient flame retardancy due to the large amount of olefin copolymer it contains.

[0010] Although the resin composition disclosed in Patent Document 2 has improved resistance to thermal shock, it does not provide specific information on tracking resistance and flame retardancy, and because it contains a large amount of olefin copolymer, its flame retardancy is considered insufficient.

[0011] Although the resin composition disclosed in Patent Document 3 achieves both tracking resistance and high / low temperature impact resistance, there is no specific description regarding flame retardancy, and because it contains a large amount of olefin copolymer, its flame retardancy is considered insufficient. [Means for solving the problem]

[0012] The inventors of this invention have conducted extensive research to solve the above problems and have arrived at the present invention. That is, the present invention has the following configuration. (1) A polyphenylene sulfide resin composition comprising (A) 100 parts by weight of polyphenylene sulfide resin, (B) 60 parts by weight or more and 150 parts by weight or less of irregularly shaped cross-section glass fibers, (C) 50 parts by weight or more and 140 parts by weight or less of non-fibrous inorganic filler, and (D) 1 part by weight or more and less than 15 parts by weight of elastomer, characterized in that the (D) elastomer contains an olefin copolymer having an epoxy group (D-1). (2) The polyphenylene sulfide resin composition according to (1), characterized in that it is compounded with (B) irregularly shaped cross-section glass fibers in an amount of more than 80 parts by weight and up to 150 parts by weight per 100 parts by weight of (A) polyphenylene sulfide resin. (3) A polyphenylene sulfide resin composition according to item (1) or (2), characterized in that it is compounded with 100 parts by weight of (A) polyphenylene sulfide resin and 100 parts by weight or more of (B) irregularly shaped cross-section glass fibers. (4) A polyphenylene sulfide resin composition according to any one of items (1) to (3), characterized in that it is compounded with (C) non-fibrous inorganic filler in an amount of more than 60 parts by weight and 140 parts by weight or less per 100 parts by weight of (A) polyphenylene sulfide resin. (5) The polyphenylene sulfide resin composition according to any one of items (1) to (4), characterized in that the (A) polyphenylene sulfide resin is melted in 20 times its weight of 1-chloronaphthalene at 250°C over 5 minutes, and the amount of residue when filtered under hot pressure using a PTFE membrane filter with a pore size of 1 μm is 4.0% by weight or less. (6) A polyphenylene sulfide resin composition according to any one of items (1) to (5), characterized in that it is compounded with 0.1 parts by weight or more and less than 9 parts by weight of the (D-1) olefin copolymer having epoxy groups per 100 parts by weight of the (A) polyphenylene sulfide resin. (7) The polyphenylene sulfide resin composition according to any one of items (1) to (6), characterized in that the olefin copolymer having the (D-1) epoxy group is an olefin copolymer containing a structure derived from the glycidyl ester of an α,β-unsaturated acid, and the content of constituent units derived from the glycidyl ester of an α,β-unsaturated acid is 0.01 parts by weight or more and less than 0.15 parts by weight when the total resin composition is 100 parts by weight. (8) A molded article comprising a polyphenylene sulfide resin composition as described in any of items (1) to (7). (9) The molded article according to item (8), characterized in that the flame retardancy measured in accordance with UL94 is V-0 at a test specimen thickness of 1.5 mmt or less. (10) The molded article according to item (8) or (9), characterized in that the molded article has a tracking resistance of 175V or more, as measured in accordance with IEC60112(2003). (11) A molded article according to any of items (8) to (10), wherein the molded article is a metal insert molded article. [Effects of the Invention]

[0013] The present invention uses glass fibers with a deformed cross-section, and by blending the PPS resin with the glass fibers with a deformed cross-section, non-fibrous inorganic fillers, and an elastomer in a predetermined ratio, it is possible to provide a PPS resin composition and its molded product that are excellent in cold and heat shock resistance and tracking resistance without significantly impairing the excellent mechanical strength and flame retardancy inherent in the PPS resin.

Brief Description of the Drawings

[0014] [Figure 1] It is a schematic diagram of the molded product used for the evaluation of cold and heat shock resistance - 1. [Figure 2] It is a schematic diagram of the molded product used for the evaluation of cold and heat shock resistance - 2.

Modes for Carrying Out the Invention

[0015] Hereinafter, embodiments of the present invention will be described in detail.

[0016] (A) PPS resin The (A) PPS resin used in the present invention is a polymer having a repeating unit represented by the following structural formula (I),

[0017]

Chemical formula

[0018] From the viewpoint of heat resistance, a polymer containing 70 mol% or more, and further 90 mol% or more, of the repeating unit represented by the above structural formula is preferable. Further, about less than 30 mol% of the repeating unit of the PPS resin may be composed of a repeating unit having the following structure or the like.

[0019]

Chemical formula

[0020] The method for producing the PPS resin used in the present invention is described below. First, the polyhalogenated aromatic compound, sulfidizing agent, polymerization solvent, molecular weight regulator, polymerization aid, and polymerization stabilizer used will be explained.

[0021] [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 that the p-dihalogenated aromatic compound accounts for 70 mol% or more, and more preferably 90 mol% or more, of the total polyhalogenated aromatic compound.

[0022] The amount of polyhalogenated aromatic compound used can be exemplified as being in the range of 0.9 to 2.0 moles, preferably 0.95 to 1.5 moles, and more preferably 1.005 to 1.2 moles per mole of sulfidizing agent, from the viewpoint of obtaining a PPS resin with a viscosity suitable for processing.

[0023] [Sulfide agents] Examples of sulfidating agents include alkali metal sulfides, alkali metal hydroxides, and hydrogen sulfide.

[0024] Specific examples of alkali metal sulfides include lithium sulfide, sodium sulfide, potassium sulfide, rubidium sulfide, cesium sulfide, and mixtures of two or more of these, with sodium sulfide being particularly preferred. These alkali metal sulfides can be used as hydrates, aqueous mixtures, or in anhydrous form.

[0025] 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.

[0026] Furthermore, sulfidating agents prepared in situ in the reaction system from alkali metal hydrosulfides and alkali metal hydroxides can also be used. Alternatively, sulfidating agents can be prepared from alkali metal hydrosulfides and alkali metal hydroxides and then transferred to a polymerization tank for use.

[0027] Alternatively, sulfidating agents 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, sulfidating agents 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.

[0028] The amount of sulfidizing agent used in the preparation shall refer to the remaining amount after deducting any loss of sulfidizing agent before the polymerization reaction begins due to dehydration or other processes from the actual amount prepared.

[0029] Furthermore, alkali metal hydroxides and / or alkaline earth metal hydroxides can be used in combination with sulfidating agents. 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, while specific examples of alkaline earth metal hydroxides include, for example, calcium hydroxide, strontium hydroxide, and barium hydroxide, with sodium hydroxide being particularly preferred.

[0030] When using alkali metal hydroxide as a sulfidating agent, it is particularly preferable to use alkali metal hydroxide simultaneously. Examples of the amount used include 0.95 to 1.20 moles, preferably 1.00 to 1.15 moles, and more preferably 1.005 to 1.100 moles per mole of alkali metal hydroxide.

[0031] [Polymerization solvent] It is preferable to use an organic polar solvent as the polymerization 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, tetramethylene sulfoxide, and mixtures thereof. These are all preferred due to their high reaction stability. Among these, N-methyl-2-pyrrolidone (hereinafter sometimes abbreviated as NMP) is particularly preferred.

[0032] The amount of organic polar solvent used is selected to be in the range of 2.0 to 10 moles, preferably 2.25 to 6.0 moles, and more preferably 2.5 to 5.5 moles per mole of sulfidating agent.

[0033] [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.

[0034] [Polymerization aid] In order 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 aids refer to substances that have the effect of increasing the viscosity of the obtained PPS resin. Specific examples of such polymerization aids include alkali metal 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, alkali metal carboxylates and / or water are preferably used.

[0035] The alkali metal carboxylates mentioned above are those with the general formula R(COOM) n The 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.

[0036] 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 alkali metal carboxylates, lithium salts have high solubility in the reaction system and a large additive 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 the most preferred choice.

[0037] When using these polymerization aids, the amount used is typically in the range of 0.01 to 0.7 moles per mole of alkali metal sulfide added to the base material. To obtain a higher degree of polymerization, a range of 0.1 to 0.6 moles is preferred, and a range of 0.2 to 0.5 moles is more preferred.

[0038] Furthermore, using water as a polymerization aid is an effective means of obtaining a resin composition with a high balance of fluidity and toughness. In this case, the amount added is usually in the range of 0.5 to 15 moles per mole of alkali metal sulfide used in the preparation, with a range of 0.6 to 10 moles being preferable, and a range of 1 to 5 moles being more preferable, in order to obtain a higher degree of polymerization.

[0039] 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. They may also be added in multiple stages. However, when using alkali metal carboxylates as polymerization aids, it is preferable to add them simultaneously 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.

[0040] [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, and 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 included as one of the polymerization stabilizers used in this invention. Furthermore, as previously mentioned, when using alkali metal hydroxides as sulfidating agents, it is particularly preferable to use alkali metal hydroxides simultaneously. In this case, excess alkali metal hydroxides relative to the sulfidating agent can also act as polymerization stabilizers.

[0041] These polymerization stabilizers can be used individually or in combination of two or more. The polymerization stabilizer is typically used in a ratio of 0.02 to 0.2 moles, preferably 0.03 to 0.1 moles, and more preferably 0.04 to 0.09 moles, per mole of alkali metal sulfide. If the ratio is too low, the stabilization effect is insufficient, while conversely, if it is too high, it is economically disadvantageous and tends to reduce the polymer yield.

[0042] There is no specific timing for adding the polymerization stabilizer; it may be added at any of the following points: during the pre-processing stage, at the start of polymerization, or during polymerization. It may also be added in multiple stages, but it is more preferable to add it simultaneously at the start of the pre-processing stage or at the start of polymerization.

[0043] Next, we will explain the pre-processing, polymerization reaction, and recovery processes in detail, step by step.

[0044] [Pre-process] Sulfidating agents are usually used in hydrate form, but it is preferable to heat the mixture containing the organic polar solvent and sulfidating agent before adding the polyhalogenated aromatic compound to remove excess water from the system. If too much water is removed in this operation, it is preferable to add water to replenish the deficit.

[0045] Furthermore, as mentioned above, alkali metal sulfides 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 as sulfidating agents. There are no particular limitations to this method, but preferably, under an inert gas atmosphere, at a temperature range of room temperature to 150°C, more preferably room temperature to 100°C, alkali metal hydroxides and alkali metal hydroxides are added to an organic polar solvent, and the temperature is raised to at least 150°C, preferably 180 to 245°C, under atmospheric pressure or reduced pressure to remove 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 and carry out the reaction.

[0046] In the polymerization reaction, the amount of water in the polymerization system is preferably 0.5 to 10.0 moles per mole of sulfidizing agent added. Here, the amount of water in the polymerization system is 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.

[0047] [Polymerization reaction process] It is preferable to produce PPS resin powder granules 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.

[0048] To initiate the polymerization reaction, a sulfidating agent and a polyhalogenated aromatic compound are added to an organic polar solvent, preferably under an inert gas atmosphere, at a temperature range of room temperature to 215°C, more preferably 100 to 215°C. A polymerization aid may also be added at this stage. The order in which these raw materials are added does not matter, and they can be added simultaneously.

[0049] The mixture is typically heated to a temperature in the range of 200°C to less than 290°C. There are no particular restrictions on the heating rate, but a rate of 0.01 to 5°C / min is usually selected, with a range of 0.1 to 3°C / min being more preferable.

[0050] Generally, the temperature is eventually raised to below 250-290°C, and the reaction is carried out at that temperature for typically 0.25-50 hours, preferably 0.5-20 hours.

[0051] A method of reacting the material at a temperature of, for example, 200°C to 245°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 245°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.

[0052] Furthermore, to obtain polymers with a higher degree of polymerization, it is effective to carry out polymerization in multiple steps. When carrying out polymerization in multiple steps, it is effective to raise the temperature to the next step when the conversion rate of the polyhalogenated aromatic compound in the system at 245°C reaches 40 mol% or more, preferably 60 mol%.

[0053] [Recovery Process] After polymerization is complete, solid material is recovered from the polymerization reaction product, which includes the polymer and solvent.

[0054] The most preferred method for recovering PPS resin is under rapid cooling conditions, and one preferred method for this recovery is the flash method. The flash method involves heating the polymerization reaction product at high temperature and high pressure (usually 250°C or higher, 8 kg / cm³). 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. Flashing here means ejecting the polymerization reaction product from a nozzle. The atmosphere used for flashing can be, for example, nitrogen or water vapor at normal pressure, and its temperature is usually selected to be in the range of 150°C to 250°C.

[0055] The flash method is an economically advantageous recovery method because it allows for the recovery of solid material simultaneously with solvent recovery, and the recovery time is relatively short. In this recovery method, ionic compounds such as sodium and low-polymerization organic oligomers tend to be incorporated into the polymer during the solidification process.

[0056] However, the method for recovering PPS resin used in the present invention is not limited to the flash method. Any method that satisfies the requirements of the present invention can be used, such as a method of slowly cooling and recovering particulate polymer (quench method). However, considering economy and performance, it is more preferable that the manufacturing method of the present invention uses PPS resin recovered by the flash method.

[0057] In the manufacturing process of PPS resin, after the polymerization reaction step and the recovery step described above, a thermal oxidation treatment may also be performed. Alternatively, a hot water treatment step and an acid treatment step may be performed before the thermal oxidation treatment step. Furthermore, a washing step with an organic solvent may be included before the acid treatment step and the hot water treatment step. The acid treatment step, the hot water treatment step, and the washing with an organic solvent can also be performed in appropriate combinations.

[0058] The acid used in the acid treatment is not particularly limited as long as it does not have the effect of decomposing the PPS resin. 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, but those that decompose and degrade the PPS resin, such as nitric acid, are undesirable.

[0059] When using an aqueous solution of acid, the water is preferably distilled water or deionized water. The aqueous solution of acid is preferably pH 1 to 7, and more preferably pH 2 to 4. A pH of 7 or less is preferable because it does not increase the metal content of the PPS resin, and a pH of 1 or more is preferable because it suppresses the amount of volatile components in the PPS resin.

[0060] The acid treatment method preferably involves immersing the PPS resin in an acid or an aqueous solution of acid, and stirring and heating may be performed as needed. The heating temperature is preferably 80 to 250°C, more preferably 120 to 200°C, and even more preferably 150 to 200°C. A temperature of 80°C or higher is preferable because it provides the acid treatment effect without increasing the metal content, and a temperature of 250°C or lower is preferable for safety because it suppresses pressure rise. Furthermore, the pH of the PPS resin after immersion treatment in an aqueous solution of acid is preferably less than 8, and more preferably between pH 2 and 8. A pH of less than 8 is preferable because it prevents an increase in the metal content of the resulting PPS resin.

[0061] The acid treatment time is preferably the time required for the reaction between the PPS resin and the acid to reach equilibrium. When treating at 80°C, 2 to 24 hours is preferred, and when treating at 200°C, 0.01 to 5 hours is preferred.

[0062] Acid treatment is preferably carried out while the PPS resin is thoroughly immersed in the acid or an aqueous solution of acid. The ratio of PPS resin to acid or aqueous solution of acid in the acid treatment is preferably 0.5 to 500 L of acid or aqueous solution of acid per 500 g of PPS resin, more preferably 1 to 100 L, and even more preferably 2.5 to 20 L. Using 0.5 L or more of acid or aqueous solution of acid per 500 g of PPS resin is preferable because it allows the PPS resin to be thoroughly immersed in the solution, suppressing poor cleaning and preventing an increase in the metal content of the PPS resin. Also, using 500 L or less of acid or aqueous solution of acid per 500 g of PPS resin is preferable because it prevents a large excess of solution relative to the PPS resin, thus preventing a significant decrease in production efficiency.

[0063] These acid treatments are carried out by methods such as adding a predetermined amount of PPS resin to a predetermined amount of water and acid, heating and stirring in a pressure vessel, or continuously performing the acid treatment. A simple method for separating the aqueous solution and the PPS resin from the treatment solution after acid treatment is filtration using a sieve or filter, and examples of methods include natural filtration, pressure filtration, vacuum filtration, and centrifugal filtration. To remove any acid or impurities remaining on the surface of the PPS resin separated from the treatment solution, it is preferable to wash it several times with water or warm water. Examples of washing methods include filtering while pouring water over the PPS resin on a filtration device, or separating the aqueous solution and the PPS resin by adding the separated PPS resin to pre-prepared water and then filtering it again. The water used for washing is preferably distilled water or deionized water.

[0064] In this invention, it is preferable to perform a hot water treatment before the acid treatment step, and the method is as follows. The water used for the hot water treatment in this invention is preferably distilled water or deionized water. The hot water treatment temperature is preferably 80 to 250°C, more preferably 120 to 200°C, and even more preferably 150 to 200°C. A temperature of 80°C or higher is preferable for safety reasons because it provides a hot water treatment effect and suppresses the amount of volatile gas generated, and a temperature of 250°C or lower suppresses the pressure rise.

[0065] The duration of the hot water treatment is preferably sufficient for the extraction of the PPS resin with hot water. When treating at 80°C, 2 to 24 hours is preferred, and when treating at 200°C, 0.01 to 5 hours is preferred.

[0066] In hot water treatment, the ratio of PPS resin to water is preferably such that the PPS resin is fully immersed in water. For every 500g of PPS resin, 0.5 to 500L of water is preferred, 1 to 100L is more preferred, and 2.5 to 20L is even more preferred. Using 0.5L or more of water per 500g of PPS resin is preferable because it ensures the PPS resin is fully immersed in water, suppressing poor cleaning and preventing an increase in the amount of volatile gas generated. Using 500L or less of water per 500g of PPS resin is also preferable because it prevents a significant excess of water relative to the PPS resin, thus preventing a substantial decrease in production efficiency.

[0067] There are no particular restrictions on these hot water treatment operations, and they can be carried out by adding a predetermined amount of PPS resin to a predetermined amount of water and heating and stirring in a pressure vessel, or by continuously applying hot water treatment. There are no particular restrictions on the method of separating the aqueous solution and PPS resin from the treatment solution after hot water treatment, but filtration using a sieve or filter is simple, and examples of methods include natural filtration, pressure filtration, vacuum filtration, and centrifugal filtration. To remove impurities remaining on the surface of the PPS resin separated from the treatment solution, it is preferable to wash it several times with water or warm water. There are no particular restrictions on the washing method, but examples of methods to separate the aqueous solution and PPS resin include filtering while pouring water over the PPS resin on a filtration device, or adding the separated PPS resin to pre-prepared water and then filtering again. The water used for washing is preferably distilled water or deionized water.

[0068] Furthermore, since the decomposition of PPS terminal groups during these acid and hot water treatments is undesirable, it is desirable to carry out the acid and hot water treatments under an inert atmosphere. Examples of inert atmospheres include nitrogen, helium, and argon, but from an economic standpoint, a nitrogen atmosphere is preferred.

[0069] The present invention may include a step of washing with an organic solvent before the acid treatment step or the hot water treatment step, and the method is as follows. The organic solvent used for washing the PPS resin in the present invention is not particularly limited as long as it does not have the effect of decomposing the PPS resin, for example, nitrogen-containing polar solvents such as N-methyl-2-pyrrolidone, dimethylformamide, dimethylacetamide, 1,3-dimethylimidazolidinone, hexamethylphosphorusamide, piperadinons, sulfoxide / sulfone solvents such as dimethyl sulfoxide, dimethyl sulfone, sulfolane, ketone solvents such as acetone, methyl ethyl ketone, diethyl ketone, acetophenone, dimethyl ether, dipropyl ether, dioxane, tetrahydrogenase Examples of suitable solvents include ether-based solvents such as chlorofuran, halogen-based solvents such as chloroform, methylene chloride, trichloroethylene, ethylene dichloride, perchloroethylene, monochloroethane, dichloroethane, tetrachloroethane, perchloroethane, and chlorobenzene, alcohol-phenol-based solvents such as methanol, ethanol, propanol, butanol, pentanol, ethylene glycol, propylene glycol, phenol, cresol, polyethylene glycol, and polypropylene glycol, and aromatic hydrocarbon-based 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. These organic solvents may be used individually or in mixtures of two or more.

[0070] Methods for cleaning with organic solvents include immersing the PPS resin in the organic solvent, and stirring or heating can 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. There are also no particular restrictions on the cleaning time. Depending on the cleaning conditions, sufficient results can usually be obtained by cleaning for 5 minutes or more in the case of batch cleaning. Continuous cleaning is also possible.

[0071] The PPS resin used in the present invention is preferably obtained by performing the above-mentioned acid treatment, hot water treatment, or washing with an organic solvent, followed by a thermal oxidation treatment. Thermal oxidation treatment involves heating the PPS resin in an oxygen atmosphere or by adding a peroxide such as H2O2 or a vulcanizing agent such as S and heating it. Heating in an oxygen atmosphere is particularly preferred due to the simplicity of the treatment.

[0072] The heating device for the thermal oxidation treatment of PPS resin may be a conventional hot air dryer or a rotary or agitator-equipped heating device. However, for efficient and more uniform processing, it is preferable to use a rotary or agitator-equipped heating device. The oxygen concentration in the atmosphere during the thermal oxidation treatment should preferably be 1 volume% or more, and more preferably 2 volume% or more. To achieve the effects of the present invention, the upper limit of the oxygen concentration is preferably 5 volume% or less. By performing the thermal oxidation treatment at an oxygen concentration of 5 volume% or less, the thermal oxidation treatment does not proceed excessively, and the toughness of the molded product containing the thermally oxidized PPS resin is not impaired. On the other hand, performing the thermal oxidation treatment at an oxygen concentration of 1 volume% or more is preferable because it allows for sufficient thermal oxidation treatment, resulting in a PPS resin with low volatile components.

[0073] The thermal oxidation treatment temperature for PPS resin is preferably 160 to 270°C, and more preferably 160 to 230°C. Performing the thermal oxidation treatment at 270°C or lower is preferable because it prevents the treatment from progressing too rapidly, thus preserving the toughness of the molded product containing the thermally oxidized PPS resin. On the other hand, performing the thermal oxidation treatment at a temperature of 160°C or higher is preferable because it allows the treatment to proceed at an appropriate rate, resulting in a PPS resin with a low amount of volatile components generated.

[0074] The treatment time for the thermal oxidation treatment is preferably 0.5 to 30 hours, more preferably 0.5 to 25 hours, and even more preferably 2 to 20 hours. A treatment time of 0.5 hours or more is preferable because it allows for sufficient thermal oxidation treatment and yields a PPS resin with low volatile components. A treatment time of 30 hours or less is preferable because it allows for control of the crosslinking reaction due to the thermal oxidation treatment and does not impair the toughness of the molded product containing the thermally oxidized PPS resin.

[0075] The melt flow rate of the PPS resin preferably used in this invention (measured according to ASTM D-1238-70 at a temperature of 315.5°C and a load of 5000g) is preferably 100g / 10min or more, and more preferably 300g / 10min. The upper limit is preferably 5000g / 10min or less, and more preferably 3000g / 10min or less. A melt flow rate of 100g / 10min or more is preferable because it allows for the acquisition of a PPS resin with excellent moldability, and a melt flow rate of 5000g / 10min or less is preferable because it allows for the acquisition of a PPS resin with excellent mechanical strength.

[0076] In this invention, the PPS resin used is preferably dissolved in 20 times its weight of 1-chloronaphthalene at 250°C for 5 minutes, and the residue amount when filtered under hot pressure using a PTFE membrane filter with a pore size of 1 μm is preferably 4.0% by weight or less. If the residue amount exceeds 4.0% by weight, it means that the thermal oxidative crosslinking of the PPS resin has progressed excessively, and the amount of gelled material in the resin has increased. Excessive thermal oxidative crosslinking of the PPS resin reduces the toughness of the PPS resin and makes it more susceptible to a decrease in thermal shock resistance, which is undesirable. There is no particular lower limit to the amount of residue, but it is preferably 1.5% or more, and more preferably 1.7% or more. If the amount of residue is less than 1.5%, the degree of thermal oxidative crosslinking is too slight, so the volatile components at melting are not reduced to a significant extent, and the volatile content reduction effect may be small.

[0077] The above-mentioned residue amount is measured using a SUS test tube equipped with a high-temperature filtration device, a pneumatic cap, and a collection funnel, with the sample being a pressed film of PPS resin approximately 80 μm thick. Specifically, a membrane filter with a pore size of 1 μm is first set in the SUS test tube, and then the pressed film of PPS resin approximately 80 μm thick and 20 times its weight of 1-chloronaphthalene are weighed and sealed. This is then placed in a high-temperature filtration device at 250°C and heated and shaken for 5 minutes. Next, a syringe containing air is connected to the pneumatic cap, and the syringe piston is pushed out to perform thermal filtration by pneumatic pressure. The specific quantitative method for the residue amount is to determine it from the weight difference between the membrane filter before filtration and the membrane filter after filtration and vacuum drying at 150°C for 1 hour.

[0078] (B) Deformed cross-section glass fiber The polyphenylene sulfide resin composition of the present invention is characterized by the essential addition of (A) 100 parts by weight of polyphenylene sulfide resin and (B) 60 to 150 parts by weight of irregularly shaped cross-section glass fibers.

[0079] The (B) irregularly shaped cross-section glass fiber of the present invention is a glass fiber having a flattened cross-section (hereinafter sometimes abbreviated as flattened glass fiber), 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 flatness ratio) is preferably 1.3 to 10. Preferably it is 1.5 to 7, and more preferably 1.5 to 5. If this flatness ratio is 1.3 or higher, the resin composition has good resistance to thermal shock, and if it is 10 or lower, the resin composition has good mechanical strength.

[0080] The flattened glass fibers preferably have a major axis of 10 to 80 μm in their cross-section, which facilitates the spinning of the glass fibers and allows for the maintenance of high strength. More preferably, the major axis is between 15 μm and 50 μm. Furthermore, the minor axis of the cross-section preferably is between 2 and 20 μm, and more preferably between 4 μm and 15 μm.

[0081] The ratio of the major axis to the minor axis (flatness) of the glass fiber cross-section was obtained by observing with a scanning electron microscope, measuring the major axis to the minor axis of the cross-section of 50 randomly selected glass fibers, calculating the ratio, and then calculating the numerical average.

[0082] By isotropizing the orientation of flattened glass fibers in a molded product, the anisotropy of the molded product is reduced, resulting in a molded product with excellent resistance to thermal shock.

[0083] The lower limit of the amount of (B) irregular cross-section glass fibers used in the present invention must be 60 parts by weight or more, preferably more than 80 parts by weight, and more preferably 100 parts by weight or more, per 100 parts by weight of (A) polyphenylene sulfide resin. The upper limit must be 150 parts by weight or less, and preferably 130 parts by weight or less. If the amount of (B) irregular cross-section glass fibers is less than 60 parts by weight per 100 parts by weight of (A) polyphenylene sulfide resin, the mechanical strength and thermal shock resistance will decrease, and if it exceeds 150 parts by weight, the flame retardancy and tracking resistance will decrease.

[0084] The (B) irregularly shaped cross-section glass fibers used in the present invention are preferably treated with a consolidating agent or a surface treatment agent. Examples of consolidating agents or surface treatment agents include functional compounds such as epoxy compounds, isocyanate compounds, silane compounds, and titanate compounds, with epoxy compounds having a high epoxy content being particularly preferred from the viewpoint of improving the reactivity of the reinforcing fibers.

[0085] Flattened glass fibers are commercially available, for example, under the product name CSG3PA-830 from Nitto Boseki Co., Ltd., and under the product name T-760FGF from Nippon Electric Glass Co., Ltd.

[0086] (C) Non-fibrous inorganic filler The polyphenylene sulfide resin composition of the present invention must contain (A) 100 parts by weight of polyphenylene sulfide resin, and (C) 50 parts by weight to 140 parts by weight of a non-fibrous inorganic filler.

[0087] Specific examples of such (C) non-fibrous inorganic fillers include fullerenes, talc, warlastenite, 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, 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. These may be hollow, and it is also possible to use two or more of these non-fibrous inorganic fillers in combination. Furthermore, these non-fibrous inorganic fillers may be pre-treated with coupling agents such as isocyanate compounds, organosilane compounds, organotitanate compounds, organoborane compounds, and epoxy compounds before use.

[0088] In particular, calcium carbonate is preferred from the viewpoint of mechanical strength and resistance to thermal shock.

[0089] The lower limit of the amount of (C) non-fibrous inorganic filler used in the present invention must be 50 parts by weight or more, preferably more than 60 parts by weight, per 100 parts by weight of (A) polyphenylene sulfide resin. The upper limit must be 140 parts by weight or less, preferably 110 parts by weight or less. If the amount of (C) non-fibrous inorganic filler is less than 50 parts by weight per 100 parts by weight of (A) polyphenylene sulfide resin, flame retardancy and tracking resistance will decrease, and if it exceeds 140 parts by weight, mechanical strength and thermal shock resistance will decrease.

[0090] (D) Elastomer The polyphenylene sulfide resin composition of the present invention comprises (A) polyphenylene sulfide resin, and (D) elastomer in an amount of 1 part by weight or more and less than 15 parts by weight. The (D) elastomer must contain (D-1) an olefin copolymer having epoxy groups.

[0091] In the present invention, the lower limit of the amount of (D) elastomer is 1 part by weight or more, preferably 3 parts by weight or more, and more preferably 6 parts by weight or more. The upper limit is less than 15 parts by weight, preferably 12 parts by weight or less, and more preferably 10 parts by weight or less. If the amount of (D) elastomer is less than 1 part by weight per 100 parts by weight of (A) polyphenylene sulfide resin, the toughness and thermal shock resistance will decrease, and if it is 15 parts by weight or more, the flame retardancy will decrease.

[0092] As a lower limit of the amount of (D-1) epoxy group-containing olefin copolymer used in the present invention, from the viewpoint of obtaining resistance to cold and thermal shock, it is preferably 0.1 parts by weight or more, more preferably 1 part by weight or more, and even more preferably 2 parts by weight or more, per 100 parts by weight of (A) polyphenylene sulfide resin. As a upper limit of the amount of (D-1) epoxy group-containing olefin copolymer, from the viewpoint of obtaining flame retardancy, it is preferably less than 9 parts by weight, preferably 7 parts by weight or less, and even more preferably 5 parts by weight or less, per 100 parts by weight of (A) polyphenylene sulfide resin.

[0093] Epoxy group-containing olefin copolymers can be obtained by introducing an epoxy group-containing monomer component (functional group-containing component) into α-olefins such as ethylene, propylene, 1-butene, 1-pentene, 1-octene, 4-methyl-1-pentene, isobutylene, or (co)polymers obtained by polymerizing two or more α-olefins, or copolymers of α-olefins with α,β-unsaturated acids such as acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, and butyl methacrylate, and their alkyl esters, such as 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. 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.

[0094] In particular, from the viewpoint of resistance to thermal shock, olefin copolymers containing structures derived from glycidyl esters of α,β-unsaturated acids are preferred, and ethylene / methyl acrylate / glycidyl methacrylate copolymers are more preferred. The lower limit of the content of constituent units derived from glycidyl esters of α,β-unsaturated acids is preferably 0.01 parts by weight or more, and more preferably 0.03 parts by weight or more, when the total resin composition is 100 parts by weight. 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 weight, and more preferably 0.10 parts by weight or less, when the total resin composition is 100 parts by weight. When the total resin composition is 100 parts by weight, the content of constituent units derived from glycidyl esters of α,β-unsaturated acids is 0.01 parts by weight or more, which maintains resistance to thermal shock, and when it is less than 0.15 parts by weight, which maintains flame retardancy.

[0095] Furthermore, as the (D) elastomer, it is preferable to use in combination (D-1) an olefin copolymer having epoxy groups and (D-2) an elastomer without polar functional groups to obtain excellent moldability and thermal shock resistance. There are no particular restrictions on the ratio of these, but a weight ratio of (D-1) / (D-2) = 5 / 95 to 95 / 5 is preferred, and a range of (D-1) / (D-2) = 10 / 90 to 90 / 10 is more preferable because it provides an excellent balance of moldability and thermal shock resistance.

[0096] On the other hand, as an elastomer that does not have (D-2) polar functional groups, copolymers similar to the olefin copolymers that constitute the olefin copolymer having (D-1) epoxy groups are preferred. Among these, ethylene / butyl acrylate copolymers are preferred from the viewpoint of resistance to thermal shock.

[0097] Furthermore, silane compounds may be optionally added to the PPS resin composition used in the present invention, to the extent that they do not impair the effects of the present invention, in order to improve mechanical strength, toughness, and other properties. Examples of silane compounds include isocyanate group-containing alkoxysilane compounds such as γ-isocyanatetopropyltriethoxysilane, γ-isocyanatetopropyltrimethoxysilane, γ-isocyanatetopropylmethyldimethoxysilane, γ-isocyanatetopropylmethyldiethoxysilane, γ-isocyanatetopropylethyldimethoxysilane, γ-isocyanatetopropylethyldiethoxysilane, and γ-isocyanatetopropyltrichlorosilane; epoxy group-containing alkoxysilane compounds such as γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; amino group-containing alkoxysilane compounds such as γ-(2-aminoethyl)aminopropylmethyldimethoxysilane, γ-(2-aminoethyl)aminopropyltrimethoxysilane, and γ-aminopropyltrimethoxysilane; and silane compounds such as modified silicone oils having epoxy groups, amino groups, isocyanate groups, and hydroxyl groups. Among these, alkoxysilanes having epoxy groups, amino groups, isocyanate groups, and hydroxyl groups are particularly suitable for obtaining excellent mechanical strength and thermal shock resistance. The preferred amount of such silane compound to be added is selected to be in the range of 0.05 to 3 parts by weight per 100 parts by weight of (A) PPS resin.

[0098] Furthermore, the PPS resin composition used in the present invention may be blended with other resins, as long as the effects of the present invention are not impaired. There are no particular limitations on the resins that can be blended, but specific examples include polyamides, polyethylene terephthalate, polyether ether ketone resins, and vinyl aromatic compound block copolymers.

[0099] Furthermore, the PPS resin composition used in the present invention may also be used with fibrous fillers that do not fall under (B) irregularly shaped cross-section glass fibers, as long as the effects of the present invention are not impaired. Specific examples of such fillers include glass fibers, carbon fibers, carbon nanotubes, carbon nanohorns, cellulose nanofibers, aramid fibers, alumina fibers, silicon carbide fibers, ceramic fibers, asbestos fibers, gypsum fibers, and metal fibers. These fillers may also be pre-treated with coupling agents such as isocyanate compounds, organosilane compounds, organotitanate compounds, organoborane compounds, and epoxy compounds before use.

[0100] Furthermore, in order to maintain high heat resistance and thermal stability without impairing the effects of the present invention, the PPS resin composition of the present invention preferably contains one or more antioxidants selected from phenolic and phosphorus-based compounds. From the viewpoint of improving heat resistance, the amount of such antioxidant is preferably 0.01 parts by weight or more, particularly 0.02 parts by weight or more, per 100 parts by weight of (A) PPS resin, and from the viewpoint of gas components generated during molding, it is preferably 5 parts by weight or less, particularly 1 part by weight or less. In addition, using phenolic and phosphorus-based antioxidants in combination is particularly preferable as it greatly enhances the effect of maintaining heat resistance and thermal stability.

[0101] 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.

[0102] 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.

[0103] The molded article made from the PPS resin composition of the present invention preferably exhibits a flame retardancy of V-0 at a test specimen thickness of 1.5 mmt or less, as measured in accordance with UL94. This makes the molded article made from the PPS resin composition applicable to products that require flame retardancy and include thin-walled sections for weight reduction. Achieving V-0 flame retardancy at a test specimen thickness of 1.5 mmt or less can be achieved by increasing the amount of polyphenylene sulfide resin, which inherently has high flame retardancy, or by increasing the amount of non-fibrous inorganic filler, which is a non-combustible component, or by decreasing the amount of elastomer, which is a combustible component. However, increasing the amount of polyphenylene sulfide resin has the disadvantage of reducing tracking resistance. Furthermore, increasing the amount of non-fibrous inorganic filler has the disadvantage of reducing mechanical strength and thermal shock resistance, and decreasing the amount of elastomer has the disadvantage of reducing thermal shock resistance. In the present invention, by (A) a polyphenylene sulfide resin of 100 parts by weight, (B) a mixture of irregularly shaped cross-section glass fibers of 60 parts by weight or more and 150 parts by weight or less, (C) a mixture of non-fibrous inorganic filler of 50 parts by weight or more and 140 parts by weight or less, and (D) an elastomer of 1 part by weight or more and less than 15 parts by weight, it is possible to achieve a balance of flame retardancy, tracking resistance, mechanical strength, and thermal shock resistance, which is preferable. Furthermore, by (D) the elastomer containing (D-1) an olefin copolymer having epoxy groups, a PPS resin composition with excellent thermal shock resistance can be obtained.

[0104] It is preferable that molded articles made from the PPS resin composition of the present invention have a tracking resistance of 175V or higher, as measured in accordance with IEC60112 (2003). IEC60664 states that for products such as automotive parts, it is undesirable (and should be considered not to use) materials with a tracking resistance of less than 175V in areas of product usage environment with a contamination degree of 3 where the product's rated voltage exceeds 630V. Therefore, molded articles made from a resin composition with a tracking resistance of 175V or higher can be applied to products to which high voltages are applied. Achieving a tracking resistance of 175V or higher is possible by reducing the amount of polyphenylene sulfide resin, which inherently has low tracking resistance, and incorporating a large amount of glass fibers or non-fibrous inorganic fillers. However, this has the drawback of reduced mechanical strength and thermal shock resistance, and the addition of a large amount of glass fibers reduces flame retardancy. In the present invention, by using glass fibers with a special cross-section, a PPS resin composition with a tracking resistance of 175V or higher, as well as excellent mechanical strength and thermal shock resistance, can be obtained.

[0105] Molded articles made from the PPS resin composition of the present invention preferably exhibit excellent thermal shock resistance in weld areas, thin-walled areas, and corner areas. Weld areas have poor thermal shock resistance because their mechanical strength is weak due to the orientation of glass fibers, and thin-walled areas and corner areas also exhibit poor thermal shock resistance because stress tends to concentrate in thermal shock resistance tests due to the difference in linear expansion coefficients between the resin and metal. Molded articles made from a PPS resin composition that exhibits excellent thermal shock resistance in weld areas, thin-walled areas, and corner areas can be applied to products used in a wide temperature range from low to high temperatures, as well as products that include thin-walled areas for the purpose of weight reduction. While it is possible to achieve excellent thermal shock resistance in weld areas, thin-walled areas, and corner areas by incorporating large amounts of elastomer or irregularly shaped cross-section glass fibers, this has the drawback of reduced flame retardancy. In the present invention, (A) a polyphenylene sulfide resin is blended in an amount of (B) irregularly shaped cross-section glass fibers of 60 to 150 parts by weight, (C) a non-fibrous inorganic filler of 50 to 140 parts by weight, and (D) an elastomer of 1 to less than 15 parts by weight, wherein the (D) elastomer contains (D-1) an olefin copolymer having epoxy groups, thereby achieving both flame retardancy and thermal shock resistance, which is preferable.

[0106] The PPS resin composition of the present invention has excellent mechanical strength, flame retardancy, thermal shock resistance, and tracking resistance, making it applicable to molded products including thin-walled sections and metal insert molded products, particularly electrical and electronic components and automotive and vehicle-related parts.

[0107] Other applicable uses of the PPS resin composition of the present invention include electrical and electronic components such as sensors, LED lamps, consumer connectors, sockets, resistors, relay cases, switches, coil bobbins, capacitors, variable capacitor cases, oscillators, various terminal boards, transformers, plugs, printed circuit boards, tuners, speakers, microphones, headphones, small motors, magnetic head bases, semiconductors, liquid crystals, FDD carriages, FDD chassis, motor brush holders, parabolic antennas, and computer-related parts; as well as household and office electrical product parts such as VTR parts, television parts, irons, hair dryers, rice cooker parts, microwave oven parts, audio parts, audio equipment parts such as audio, laser discs (registered trademark), and compact discs; lighting parts, refrigerator parts, air conditioner parts, typewriter parts, and word processor parts.Other parts include: office computer parts, telephone parts, facsimile parts, photocopier parts, cleaning jigs, motor parts, lighters, typewriters, and other mechanical parts; optical instruments such as microscopes, binoculars, cameras, and watches; precision machinery parts; water supply parts such as faucet valves, mixing faucets, pump parts, pipe joints, water volume control valves, relief valves, water temperature sensors, water volume sensors, and water meter housings; valves such as alternator terminals, alternator connectors, IC regulators, light dew potentiometer bases, exhaust gas valves, and various other valves; various pipes for fuel, exhaust, and intake systems; air intake nozzle snorkels, intake manifolds, fuel pumps, engine coolant joints, carburetor main bodies, carburetor spacers, exhaust gas sensors, coolant sensors, oil temperature sensors, and throttle position sensors. Examples of applications include various automotive and vehicle-related parts such as crankshaft position sensors, airflow meters, brake pad wear sensors, thermostat bases for air conditioners, heating hot air flow control valves, brush holders for radiator motors, water pump impellers, water pump housings, engine cooling modules, turbine vanes, wiper motor related parts, distributors, starter switches, starter relays, transmission wire harnesses, windshield washer nozzles, air conditioning panel switch boards, fuel-related solenoid valve coils, fuse connectors, horn terminals, electrical component insulating plates, stepper motor rotors, lamp sockets, lamp reflectors, lamp housings, brake pistons, solenoid bobbins, engine oil filters, ignition system cases, vehicle speed sensors, cable liners, and more. [Examples]

[0108] 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.

[0109] [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.

[0110] (2)Residue amount A 1 μm pore-size PTFE membrane filter, pre-weighed and fitted with a pneumatic cap and collection funnel, was placed in a SUS test tube manufactured by Senshu Scientific. 100 mg of PPS resin, pressed into a film approximately 80 μm thick, and 2 g of 1-chloronaphthalene were weighed into the filter and then sealed. This was inserted into a Senshu Scientific high-temperature filtration device SSC-9300 and heated and shaken at 250°C for 5 minutes to dissolve the PPS resin in 1-chloronaphthalene. A 20 mL syringe containing air was connected to the pneumatic cap, and the piston was pushed out to filter the solution through the membrane filter. The membrane filter was removed, vacuum-dried at 150°C for 1 hour, and then weighed. The difference in weight of the membrane filter before and after filtration was defined as the residue amount (weight %).

[0111] [Example] Preparation of PPS 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), 1.89 kg (23.10 mol) of sodium acetate, 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.

[0112] The mixture was then cooled to 200°C, and 10.45 kg (71.07 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.

[0113] 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.

[0114] 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.

[0115] 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.

[0116] The obtained PPS had an MFR of 600 g / 10 min and a residue content of 0.7% by weight.

[0117] The raw materials used in the examples and comparative examples are shown below. (A)PPS resin PPS-1: PPS resin polymerized by the method described in the reference example was subjected to thermal oxidation treatment at an oxygen concentration of 2%, 220°C, and for 12 hours. The resulting PPS had an MFR of 400 g / 10 min and a residue amount of 1.9% by weight. PPS-2: PPS resin polymerized by the method described in the reference example was subjected to thermal oxidation treatment at an oxygen concentration of 11% at 220°C for 12 hours. The resulting PPS had an MFR of 100 g / 10 min and a residue amount of 13% by weight. (B) Deformed cross-section glass fiber B-1: Chopped strand (T-760FGF manufactured by Nippon Electric Glass Co., Ltd., 3mm length, minor diameter 7μm, major diameter 28μm, flatness 4) (B') Circular cross-section glass fiber B'-1: Chopped strand (T-760H manufactured by Nippon Electric Glass Co., Ltd., 3mm length, average fiber diameter 10.5μm, flatness 1) (C) Non-fibrous inorganic filler C-1: Heavy calcium carbonate (Escalon #800, manufactured by Sankyo Flour Milling Co., Ltd., 50% average particle size 3.5 μm) (D) Elastomer D-1(a): Ethylene-glycidyl methacrylate-methyl acrylate copolymer (Bondfast 7M manufactured by Sumitomo Chemical Co., Ltd., 67% by mass of ethylene, 6% by mass of glycidyl methacrylate, 27% by mass of methyl acrylate) D-1(b): Ethylene-glycidyl methacrylate-methyl acrylate copolymer (Bondfast 7L manufactured by Sumitomo Chemical Co., Ltd., 70% by mass of ethylene, 3% by mass of glycidyl methacrylate, 27% by mass of methyl acrylate) D-2(a): Ethylene n-butyl acrylate copolymer (Rotril 35BA40, manufactured by Arkema Corporation).

[0118] [Method for measuring and evaluating molded articles made from resin compositions] The measurement and evaluation methods in this embodiment and comparative example are as follows.

[0119] (1) Flame retardant Resin composition pellets were supplied to a Sumitomo Heavy Industries, Ltd. injection molding machine (SE-50D) set to a cylinder temperature of 320°C and a mold temperature of 145°C. Using a mold with the UL test specimen shape specified in UL94, injection molding was performed under the following conditions: injection speed of 120 mm / s, injection pressure equal to the injection pressure when the test specimen was filled to the tip plus 5 MPa, injection time of 8 s, and cooling time of 10 s to obtain evaluation test specimens. The flame retardancy of these test specimens was evaluated in accordance with the UL94 vertical test. Flame retardancy was ranked in the order of V-0 > V-1 > V-2, with those that did not meet V-2 being indicated as V-out. Test specimen thicknesses of 1.5 mm and 0.7 mm were used. For the same flame retardancy rank, thinner test specimens exhibited better flame retardancy, and it was preferable to show V-0 with a thickness of 1.5 mm or less.

[0120] (2) Tracking resistance Resin composition pellets were supplied to a Sumitomo Heavy Industries, Ltd. injection molding machine (SE50DUZ-C160) set to a cylinder temperature of 320°C and a mold temperature of 130°C. Using a mold for a rectangular plate (80mm x 80mm x 3.0mmt), injection molding was performed under conditions of a filling time of 0.5s and a holding pressure of 50% of the filling pressure to obtain a rectangular plate (80mm x 80mm x 3.0mmt). Using this test piece, the maximum voltage at which tracking failure did not occur was measured in accordance with IEC60112 (2003). A 0.1% aqueous ammonium chloride solution was used as the electrolyte. The higher this maximum voltage, the better the tracking resistance, and 175V or higher is preferable.

[0121] (3) Thermal shock resistance -1 Resin composition pellets were supplied to a Sumitomo Heavy Industries, Ltd. injection molding machine (SE-30D) set to a cylinder temperature of 320°C and a mold temperature of 130°C. A cassette-shaped metal with two holes in the center was set in the mold, and injection molding was performed under conditions of a filling time of 0.5 s and a holding pressure of 60% of the filling pressure to obtain the evaluation metal insert test piece shown in Figure 1. This test piece was subjected to thermal shock treatment, with one 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 checked every 10 cycles. This test piece was intentionally designed to have a weld area by providing a hole in the center, and its thermal shock resistance was simulated. Thermal shock resistance was evaluated based on the number of cycles at which cracks were observed. If no cracks occurred for 50 cycles or more, it can be said that the product is at a level that is not problematic for practical use. However, the more treatments required for cracks to occur, the better the thermal shock resistance, which is preferable.

[0122] (4) Thermal shock resistance -2 Resin composition pellets were supplied to a Sumitomo Heavy Industries, Ltd. injection molding machine (SE-50DUZ) with the cylinder temperature set to 320°C and the mold temperature to 130°C. A metal block was set in the mold, and injection molding was performed at an injection speed of 100 mm / s, an injection pressure equal to the injection pressure when the test piece was filled to the tip plus 5 MPa, and an injection time of 12 s to obtain the evaluation metal insert test piece shown in Figure 2. This test piece was subjected to thermal shock treatment, with one 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 checked every 10 cycles. This test piece has a thin wall thickness of 0.6 mm at its thinnest point, and stress tends to concentrate at the corners, thus simulating the thermal shock resistance of the thin-walled and corner sections. Thermal shock resistance was evaluated based on the number of cycles at which crack formation was observed. While a product can be considered practically acceptable if no cracks occur after 300 cycles or more, a higher number of treatment cycles before cracks appear is preferable, as it results in superior resistance to thermal shock.

[0123] (5) Tensile strength Resin composition pellets were supplied to a Sumitomo Heavy Industries, Ltd. injection molding machine (SE-50D) set to a cylinder temperature of 310°C and a mold temperature of 145°C. Injection molding was performed using a mold of type A1 test specimen shape as specified in ISO 20753 (2008) with a filling time of 0.8 s and a holding pressure of 75% of the filling pressure to obtain evaluation test specimens. These test specimens were conditioned for 16 hours at 23°C and 50% relative humidity. Then, under the same conditions of 23°C and 50% relative humidity, with a grip distance of 115 mm and a test speed of 5 mm / min, the tensile strength was measured in accordance with ISO 527-1, -2 (2012). A tensile strength of 140 MPa or higher is considered a product level acceptable for practical use; however, a higher value indicates superior mechanical strength and is preferable.

[0124] [Examples 1-7, Comparative Examples 1-8] Using a twin-screw extruder (TEM-26SS, manufactured by Toshiba Machine Co., Ltd.) with a 26 mm diameter intermediate additive port, set to a cylinder temperature of 320°C and a screw rotation speed of 400 rpm, (C) non-fibrous inorganic filler and (D) elastomer were added to 100 parts by weight of (A) PPS resin obtained in Reference Examples 1 and 2 from the raw material supply port in the weight ratios shown in Tables 1 and 2 to bring it to a melted state. (B) irregular cross-section glass fibers and (B') circular cross-section glass fibers were supplied from the intermediate additive port in the weight ratios shown in Tables 1 and 2, and the mixture was melt-kneaded at a discharge rate of 30 kg / hour to obtain PPS resin composition pellets. The above-mentioned properties were evaluated using these PPS resin composition pellets. The results are shown in Tables 1 and 2.

[0125] In the table of examples, "Glycidyl ester content of α,β-unsaturated acid in the resin composition" refers to the content of constituent units derived from glycidyl ester of α,β-unsaturated acid when the total resin composition is 100 parts by weight.

[0126] [Table 1]

[0127] [Table 2]

[0128] Examples 1 to 7 showed that by using (B) irregularly shaped cross-section glass fibers and mixing each of the components (A) to (D) in predetermined amounts, a well-balanced and excellent performance was achieved in flame retardancy (V-0 for specimen thickness of 1.5 mmt or less), tracking resistance (175V or higher), thermal shock resistance -1 (50 cycles or more), thermal shock resistance -2 (300 cycles or more), and tensile strength.

[0129] Comparative Example 1 showed that (B) had inferior thermal shock resistance because it did not use irregularly shaped cross-section glass fibers.

[0130] Comparative Example 2 showed that (B) the irregularly shaped cross-section glass fibers were in amounts of less than 60 parts by weight per 100 parts by weight of (A) PPS resin, and (C) the non-fibrous inorganic filler was in amounts of more than 140 parts by weight per 100 parts by weight of (A) PPS resin, resulting in inferior thermal shock resistance and tensile strength.

[0131] Comparative Example 3 showed that (B) the amount of irregularly shaped cross-section glass fibers exceeded 150 parts by weight per 100 parts by weight of (A) PPS resin, and (C) the amount of non-fibrous inorganic filler was less than 50 parts by weight per 100 parts by weight of (A) PPS resin, resulting in poor flame retardancy. Comparative Example 4 showed that (B) the irregularly shaped cross-section glass fibers were in amounts of less than 60 parts by weight per 100 parts by weight of (A) PPS resin, and (C) the non-fibrous inorganic filler was in amounts of less than 50 parts by weight per 100 parts by weight of (A) PPS resin, resulting in poor tracking resistance.

[0132] Comparative Example 5 showed that (D) the absence of elastomer resulted in inferior resistance to thermal shock.

[0133] Comparative Examples 6 and 7 showed that the amount of (D) elastomer was 15 parts by weight or more per 100 parts by weight of (A) PPS resin, and that it was inferior in flame retardancy.

[0134] Comparative Example 8 showed that the (D) elastomer does not contain an elastomer containing an olefin copolymer having an epoxy group (D-1), and therefore has poor resistance to thermal shock. [Industrial applicability]

[0135] The resin composition of the present invention is suitable for molded products such as automotive parts and electrical and electronic components that include thin-walled sections and have metal inserts, because it has excellent resistance to thermal shock and tracking without significantly impairing the excellent mechanical strength and flame retardancy inherent in PPS resin. [Explanation of symbols]

[0136] 1. Insert metal 2. Gate 3. Metal insert molded product 4. Insert metal 5. Gate 6. Metal insert molded product

Claims

1. A polyphenylene sulfide resin composition comprising 100 parts by weight of (A) polyphenylene sulfide resin, 60 to 150 parts by weight of (B) modified cross-section glass fiber, 50 to 140 parts by weight of (C) non-fibrous inorganic filler, and 1 to less than 15 parts by weight of (D) elastomer, wherein the (D) elastomer contains (D-1) an olefin copolymer having an epoxy group, the (D-1) olefin copolymer having an epoxy group is an olefin copolymer containing a structure derived from a glycidyl ester of an α,β-unsaturated acid, and the content of the structural unit derived from the glycidyl ester of an α,β-unsaturated acid is 0.01 to less than 0.15 parts by weight, based on 100 parts by weight of the entire resin composition.

2. 2. The polyphenylene sulfide resin composition according to claim 1, characterized in that the modified cross section glass fiber (B) is blended in an amount of more than 80 parts by weight and not more than 150 parts by weight per 100 parts by weight of the polyphenylene sulfide resin (A).

3. 2. The polyphenylene sulfide resin composition according to claim 1, characterized in that the modified cross section glass fiber (B) is blended in an amount of 100 parts by weight or more and 150 parts by weight or less with respect to 100 parts by weight of the polyphenylene sulfide resin (A).

4. 2. The polyphenylene sulfide resin composition according to claim 1, characterized in that the non-fibrous inorganic filler (C) is blended in an amount of more than 60 parts by weight and not more than 140 parts by weight per 100 parts by weight of the polyphenylene sulfide resin (A).

5. 2. The polyphenylene sulfide resin composition according to claim 1, wherein the polyphenylene sulfide resin (A) is a polyphenylene sulfide resin which, when melted in 20 times its weight of 1-chloronaphthalene at 250°C for 5 minutes and filtered under pressure with a PTFE membrane filter having a pore size of 1 μm under hot pressure, leaves a residue of 4.0% by weight or less.

6. The polyphenylene sulfide resin composition according to claim 1, characterized in that the polyphenylene sulfide resin (A) is obtained by blending 0.1 parts by weight or more and less than 9 parts by weight of the olefin copolymer having an epoxy group (D-1) with 100 parts by weight of the polyphenylene sulfide resin (A).

7. A molded article made from the polyphenylene sulfide resin composition according to any one of claims 1 to 6.

8. 8. The molded article according to claim 7, wherein the flame retardancy of the molded article measured in accordance with UL94 is V-0 for a test piece having a thickness of 1.5 mmt or less.

9. 8. The molded article according to claim 7, wherein the molded article has a tracking resistance of 175 V or more as measured in accordance with IEC 60112 (2003).

10. The molded article according to claim 7, wherein the molded article is a metal insert molded article.

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