Motor component using a cooling medium

Abstract

Provided is a motor component using a cooling medium that is excellent in cold-heat shock resistance even after treatment by immersion in a cooling medium and that can be used in a severe environment in contact with a cooling medium. A motor component using a cooling medium, characterized by being obtained by molding a polyphenylene sulfide resin composition in which (A) a polyphenylene sulfide resin, (B) an elastomer, (C) a fibrous filler, and (D) a non-fibrous filler are mixed, a molded product formed from the polyphenylene sulfide resin composition has a tensile elastic modulus of 10 GPa or more and 21 GPa or less, and when the tensile strength in the resin flow direction of the molded product is denoted as MD and the tensile strength in the direction perpendicular to the resin flow direction is denoted as TD, MD is 70 MPa or more, and the ratio of MD to TD, MD / TD, is 1.4 or less.

Description

Technical Field

[0001] This invention relates to motor components that utilize a cooling medium and exhibit excellent resistance to thermal shock after being impregnated in a cooling medium. Background Technology

[0002] In recent years, various efforts have been made regarding global warming and energy issues from the perspective of minimizing environmental impact. Among these efforts, to reduce carbon dioxide and nitrogen oxide emissions during driving, electric vehicles using electric motors in their drive mechanisms, fuel cell vehicles, and hybrid vehicles combining gasoline engines and electric motors are becoming increasingly popular as next-generation vehicles.

[0003] In electric vehicles, with the increasing capacity of batteries and the high output of motors, the heat generated by batteries and motors increases, consequently increasing the heat generated by electrical components such as inverters and DC-DC converters that carry high-voltage currents. Furthermore, to save space and improve efficiency, the integration of motors with gears and inverters, as well as their integration with DC-DC converters, power distribution units, PTC heaters, and on-board chargers, has been studied. Products incorporating these motors, known as electric axles (hereinafter sometimes simply e-axles), face the problem of rising overall system ambient temperature due to increased heat generation and space-saving considerations. Therefore, improving the durability of components to the cooling medium used for cooling becomes extremely important for improving the efficiency of thermal management systems and extending the lifespan of system components.

[0004] On the other hand, thermoplastic resins have traditionally been used for electrical components such as motors, especially those with embedded metal parts, considering factors such as lightweight, good processability, and low cost. Furthermore, as an example of motor components, in resin-molded parts composed of metal inserts such as busbars, even in environments with varying temperatures, such as low temperatures due to use in cold regions and high temperatures due to motor heat generation, resin compositions with excellent resistance to thermal shock and preventing cracking of the metal inserts are required.

[0005] In electric vehicles, polyphenylene sulfide (PPS) resin, which has high heat resistance or chemical resistance at high temperatures, is widely used. Compared with other engineering plastics, PPS resin has poor resistance to thermal shock and tracking. Therefore, Patent Document 1 describes a resin composition that combines tracking resistance and high and low temperature shock resistance by containing a specified amount of inorganic filler and olefin copolymer in PPS resin.

[0006] Furthermore, Patent Document 2 describes a resin composition that combines thermal shock resistance, flame retardancy, and tracking resistance by mixing a specified amount of irregularly shaped cross-section glass fiber and non-fibrous inorganic filler and epoxy-based olefin copolymer into PPS resin.

[0007] In addition, Patent Document 3 describes a heat dissipation component for motor cooling, which is formed by molding a resin composition containing a specified amount of magnesium hydroxide and glass fibers with a fiber diameter of 4 to 11 μm in PPS resin to achieve efficient heat dissipation relative to the increase in motor output. The heat conductivity is 0.8 W / m·K or higher.

[0008] Existing technical documents

[0009] Patent documents

[0010] Patent Document 1: Japanese Patent Application Publication No. 2020-105502

[0011] Patent Document 2: Japanese Patent Application Publication No. 2023-68631

[0012] Patent Document 3: Japanese Patent Application Publication No. 2012-36386 Summary of the Invention

[0013] The problem that the invention aims to solve

[0014] Regarding thermal management systems for electric vehicles, including batteries, inverters, and motor components, cooling systems utilize air cooling, water cooling, and oil cooling. Historically, motor components primarily used oil for lubrication and cooling, while batteries and inverters often used water (coolant) with high thermal conductivity. In recent years, due to increased heat generation in such systems, the components require durable cooling media. Furthermore, the use of oil and water (coolant) is increasingly separated within the system, requiring meticulous control of each cooling medium. Therefore, components must exhibit high durability with any cooling medium. As a key aspect of durability, resin components used in environments with high ambient temperatures due to heat sources and cooling media must maintain high strength and rigidity, preventing cracking and preserving their shape even when immersed in the cooling media. Therefore, for the use of thermoplastic resins in motor components employing cooling media, resistance to thermal shock after impregnation with the cooling media is crucial.

[0015] However, although the resin compositions disclosed in Patent Documents 1 and 2 have improved resistance to thermal shock, they do not disclose motor components that exhibit excellent resistance to thermal shock and are suitable for use with cooling media after being impregnated in a cooling medium.

[0016] Although the heat dissipation component for motor cooling disclosed in Patent Document 3 is a motor component, it is not disclosed to be applicable to motors using a cooling medium.

[0017] Problem-solving methods

[0018] To solve the aforementioned problems, the inventors conducted repeated and in-depth research, and discovered that molded articles formed from a PPS resin composition containing PPS resin, an elastomer, a fibrous filler, and a non-fibrous filler meet specified characteristics, improve the adhesion between the resin and the metal, and maintain rigidity. Therefore, even after heat treatment in a cooling medium, they exhibit previously unknown properties such as excellent resistance to thermal shock. Molded articles with these properties are suitable for motor components using cooling media. In other words, the present invention has the following structure.

[0019] [1]. A motor component using a cooling medium is obtained by molding a polyphenylene sulfide resin composition containing (A) polyphenylene sulfide resin, (B) elastomer, (C) fibrous filler and (D) non-fibrous filler. The molded article formed from the polyphenylene sulfide resin composition has a tensile modulus of 10 GPa or more and 21 GPa or less. When the tensile strength of the molded article in the resin flow direction is denoted as MD and the tensile strength in the direction perpendicular to the resin flow direction is denoted as TD, MD is 70 MPa or more and the ratio of MD to TD, i.e., MD / TD, is 1.4 or less.

[0020] [2]. The motor component using a cooling medium as described in [1], wherein the polyphenylene sulfide resin composition is mixed with an epoxy-based olefin copolymer (B-1) as the elastomer of (B), and the amount of (B-1) epoxy-based olefin copolymer mixed with 0.1 parts by mass and less than 9 parts by mass relative to 100 parts by mass of the polyphenylene sulfide resin of (A) is 0.1 parts by mass and less than 9 parts by mass.

[0021] [3]. Motor components using a cooling medium as described in [1] or [2], wherein the polyphenylene sulfide resin composition contains at least 60 parts by weight of (D) non-fibrous filler relative to 100 parts by weight of (A) polyphenylene sulfide resin.

[0022] [4]. A motor component using a cooling medium as described in any of [1] to [3], wherein the cooling medium comprises at least one selected from long-life coolant LLC, ethylene glycol, oil and water.

[0023] [5]. Motor components using a cooling medium as described in any of [1] to [4], wherein the molded articles formed from the polyphenylene sulfide resin composition are molded articles formed by metal insert injection molding.

[0024] [6]. A motor component using a cooling medium as described in any of [1] to [5], for use in a stator, rotor, slip ring, current sensor, busbar, rotation angle sensor, cooling medium flow line and cooling medium spray component.

[0025] [7]. Motor components using a cooling medium as described in any of [1] to [6], wherein the thinnest part of the molded article formed from the polyphenylene sulfide resin composition is 0.7 mm or less.

[0026] [8]. Motor components using a cooling medium as described in any of [1] to [7], wherein the MD and TD of the molded articles formed from the polyphenylene sulfide resin composition are both 80 MPa or higher.

[0027] [9]. A method for molding a motor component using a cooling medium is to obtain a molded article by molding a polyphenylene sulfide resin composition containing (A) polyphenylene sulfide resin, (B) elastomer, (C) fibrous filler and (D) non-fibrous filler. The molded article has a tensile modulus of elasticity of 10 GPa or more and 21 GPa or less. When the tensile strength of the molded article in the resin flow direction is denoted as MD and the tensile strength in the direction perpendicular to the resin flow direction is denoted as TD, MD is 70 MPa or more and the ratio of MD to TD, i.e., MD / TD, is 1.4 or less.

[0028]

[10] . As described in [9], the polyphenylene sulfide resin composition is mixed with an epoxy-based olefin copolymer (B-1) as the elastomer of (B), and the amount of (B-1) epoxy-based olefin copolymer mixed with 0.1 parts by mass and less than 9 parts by mass relative to 100 parts by mass of the polyphenylene sulfide resin of (A) is 0.1 parts by mass and less than 9 parts by mass.

[0029]

[11] . As in [9] or

[10] , the polyphenylene sulfide resin composition contains at least 60 parts by weight of (D) non-fibrous filler relative to 100 parts by weight of (A) polyphenylene sulfide resin.

[0030]

[12] . The method of any one of [9] to

[11] , wherein the cooling medium comprises at least one selected from long-life coolant LLC, ethylene glycol, oil and water.

[0031]

[13] . The method of any one of [9] to

[12] , wherein the molded article formed from the polyphenylene sulfide resin composition is a molded article formed by injection molding with metal inserts.

[0032]

[14] . The method of any of [9] to

[13] uses a motor component with a cooling medium selected from a stator, rotor, slip ring, current sensor, busbar, rotation angle sensor, cooling medium flow line and cooling medium spray component.

[0033]

[15] . The method of any one of [9] to

[14] , wherein the thinnest part of the molded article formed from the polyphenylene sulfide resin composition is less than 0.7 mm.

[0034]

[16] . The method described in any of [9] to

[15] shall have a MD and TD of 80 MPa or higher for the molded article formed from the polyphenylene sulfide resin composition.

[0035]

[17] . The use of a molded article for a motor component using a cooling medium, the molded article being a molded article obtained by molding a polyphenylene sulfide resin composition containing (A) polyphenylene sulfide resin, (B) elastomer, (C) fibrous filler and (D) non-fibrous filler, having a tensile modulus of elasticity of 10 GPa or more and 21 GPa or less, wherein the tensile strength of the molded article in the resin flow direction is denoted as MD and the tensile strength in the direction perpendicular to the resin flow direction is denoted as TD, the MD is 70 MPa or more, and the ratio of MD to TD, i.e., MD / TD, is 1.4 or less.

[0036]

[18] . As described in

[17] , the polyphenylene sulfide resin composition is mixed with an epoxy-based olefin copolymer (B-1) as the elastomer of (B), wherein the amount of (B-1) epoxy-based olefin copolymer is 0.1 parts by mass and less than 9 parts by mass relative to 100 parts by mass of the polyphenylene sulfide resin of (A).

[0037]

[19] . As described in

[17] or

[18] , the polyphenylene sulfide resin composition contains at least 60 parts by weight of (D) non-fibrous filler relative to 100 parts by weight of (A) polyphenylene sulfide resin.

[0038]

[20] . For any of the uses described in

[17] to

[19] , the cooling medium comprises at least one selected from long-life coolant LLC, ethylene glycol, oil and water.

[0039]

[21] . For any of the uses described in

[17] to

[20] , the molded article formed from the polyphenylene sulfide resin composition is a molded article formed by injection molding with metal inserts.

[0040]

[22] . The motor component using a cooling medium is used for any of the applications described in

[17] to

[21] , selected from stator, rotor, slip ring, current sensor, busbar, rotation angle sensor, cooling medium flow line and cooling medium spray component.

[0041]

[23] . For any of the uses described in

[17] to

[22] , the thinnest part of the molded article formed from the polyphenylene sulfide resin composition is less than 0.7 mm.

[0042]

[24] . For any of the uses described in

[17] to

[23] , the molded articles formed from the polyphenylene sulfide resin composition have a MD and TD of 80 MPa or more.

[0043] Invention Effects

[0044] According to the present invention, a motor component using a cooling medium can be provided that exhibits excellent resistance to thermal shock even after being immersed in a cooling medium and subjected to heat treatment. Attached Figure Description

[0045] Figure 1 This is a schematic diagram of a molded article used for evaluating resistance to thermal shock. Detailed Implementation

[0046] The molded article formed from a PPS resin composition containing PPS resin, elastomer, fibrous filler, and non-fibrous filler of the present invention has a tensile modulus of elasticity of 10 GPa or more and 21 GPa or less. When the tensile strength in the resin flow direction of the molded article is denoted as MD and the tensile strength in the vertical direction is denoted as TD, the MD is 70 MPa or more and the MD / TD is 1.4 or less. As a result, it exhibits excellent resistance to thermal shock even after heat treatment by immersion in a cooling medium. Such previously unknown properties have been discovered. Moreover, the molded article formed from this PPS resin composition can be used for a new application: motor parts that use a cooling medium.

[0047] The embodiments of the present invention will be described below.

[0048] (A) PPS resin

[0049] The polyphenylene sulfide resin (A) used in this invention is a polymer having repeating units as shown in the following structural formula.

[0050] From the viewpoint of heat resistance, the (A) polyphenylene sulfide resin used in this invention is preferably a polymer containing 70 mol% or more, and more preferably 90 mol% or more, of the repeating units shown in the above structural formula. Alternatively, the (A) polyphenylene sulfide resin used in this invention may also contain less than 30 mol% of repeating units composed of repeating units having the following structure.

[0051] Next, the method for obtaining the (A) polyphenylene sulfide resin used in this invention will be described. The manufacturing method of PPS resin preferably comprises a pre-processing step, a polymerization reaction step, a recycling step, and a post-processing step, and can be manufactured using known methods. Regarding the raw materials and pre-processing steps used in the manufacture of PPS resin, the method described in Japanese Patent Application Publication No. 2017-155221 is preferred. Hereinafter, the polymerization reaction step, the recycling step, and the post-processing step will be described.

[0052] [Polymerization reaction process]

[0053] PPS resin powder is preferably manufactured by reacting a vulcanizing agent and a polyhalogenated aromatic compound in an organic polar solvent at a temperature range of 200°C to 290°C.

[0054] At the start of the polymerization reaction, preferably under an inert gas atmosphere and at a temperature range of room temperature to 215°C, more preferably 100°C to 215°C, a vulcanizing agent and a polyhalogenated aromatic compound are added to an organic polar solvent. Polymerization aids may also be added at this stage. The order in which these raw materials are fed can vary or they can be fed simultaneously.

[0055] The mixture is typically heated to a temperature range of 200°C to 290°C. There are no particular restrictions on the heating rate, but a rate of 0.01 to 5°C / minute is preferred, and a range of 0.1 to 3°C / minute is more preferable.

[0056] Typically, the temperature is eventually raised to 250–290°C, and the reaction is carried out at this temperature for 0.25–50 hours, preferably 0.5–20 hours.

[0057] Reacting at 200°C to 245°C for a certain time before reaching the final temperature, and then raising the temperature to 270°C to 290°C, is effective for obtaining a higher degree of polymerization. In this case, the reaction time at 200°C to 245°C is typically preferred to be in the range of 0.25 hours to 20 hours, and more preferably in the range of 0.25 hours to 10 hours.

[0058] Furthermore, to obtain polymers with higher degrees of polymerization, it is effective to perform polymerization in multiple stages. When performing polymerization in multiple stages, it is effective to raise the temperature to the next stage when the conversion rate of polyhalogenated aromatic compounds in the system at 245°C reaches 40 mol% or more, preferably 60 mol%.

[0059] [Recycling Process]

[0060] After polymerization is complete, solids are recovered from the polymerization reactants containing polymers, solvents, etc.

[0061] The most preferred method for recycling PPS resin is under quenching conditions. One preferred method is the flash evaporation process. The flash evaporation process involves removing the polymer from a high-temperature, high-pressure environment (typically above 250°C and 8 kg / cm³). 2 The above-mentioned flash discharge is a method in which the polymer is converted into powder form and recovered while the solvent is being recycled in an atmosphere of normal or reduced pressure. Flash discharge here means that the polymer reactants are sprayed out from a nozzle. The atmosphere for flash discharge is, for example, nitrogen or water vapor at normal pressure, and the temperature is usually preferably in the range of 150°C to 250°C.

[0062] Flash evaporation can recover both solvent and solids simultaneously, and the recovery time is relatively short, making it an economically advantageous recovery method. In this recovery method, during the solidification process, ionic compounds, such as sodium, or low-polymerization organic compounds (oligomers) tend to be easily incorporated into the polymer.

[0063] However, the method for recovering PPS resin used in this invention is not limited to the flash evaporation method. Any method that meets the requirements of this invention may be used, such as a method for recovering granular polymers by slow cooling (quenching method). However, considering economy and performance, PPS resin recovered by the flash evaporation method is more preferred as a method for manufacturing this invention.

[0064] [Post-processing steps (acid treatment)]

[0065] In this invention, it is preferable to subject the PPS resin obtained through the above-described polymerization reaction process and recycling process to acid treatment.

[0066] There are no particular restrictions on the acids used in acid treatment as long as they do not decompose PPS resin. Examples include acetic acid, hydrochloric acid, sulfuric acid, phosphoric acid, silicic acid, carbonic acid, and propionic acid. Acetic acid and hydrochloric acid are preferred, but acids such as nitric acid, which can decompose and degrade PPS resin, are not preferred.

[0067] When using an aqueous solution of acid, distilled water or deionized water is preferred. The aqueous solution of acid is preferably at a pH of 1 to 7, more preferably at a pH of 2 to 4. Maintaining a pH below 7 prevents an increase in the metal content of the PPS resin, and therefore is preferred. Maintaining a pH above 1 suppresses the amount of volatile components in the PPS resin, and is therefore also preferred.

[0068] As a method of acid treatment, it is preferable to impregnate the PPS resin in an acid or an aqueous solution of acid, and stirring and heating may also be used as needed. The heating temperature is preferably 80–250°C, more preferably 120–200°C, and even more preferably 150–200°C. Setting the temperature above 80°C ensures the acid treatment effect without increasing the metal content, which is therefore preferable. Setting the temperature below 250°C suppresses pressure rise, which is preferable for safety. Furthermore, the pH of the PPS resin after impregnation with the aqueous acid solution is preferably less than 8, more preferably pH 2–8. By making the pH less than 8, the metal content of the resulting PPS resin will not increase, which is therefore preferable.

[0069] The preferred acid treatment time is the time when the reaction between PPS resin and acid reaches full equilibrium. When treated at 80°C, the preferred time is 2 to 24 hours, and when treated at 200°C, the preferred time is 0.01 to 5 hours.

[0070] Acid treatment is preferably performed while the PPS resin is fully immersed in acid or an aqueous solution of acid. Regarding the ratio of PPS resin to acid or aqueous solution of acid in acid treatment, it is preferably 0.5 to 500 L of acid or aqueous solution of acid relative to 500 g of PPS resin, more preferably 1 to 100 L, and even more preferably 2.5 to 20 L. By using 0.5 L or more of acid or aqueous solution relative to 500 g of PPS resin, the PPS resin can be fully immersed in the aqueous solution, thus suppressing poor cleaning and preventing an increase in the metal content of the PPS resin, which is therefore preferable. Furthermore, by using less than 500 L of acid or aqueous solution relative to 500 g of PPS resin, the solution volume relative to the PPS resin is not excessive, and production efficiency is not significantly reduced, which is also preferable.

[0071] These acid treatments are performed by adding a specified amount of PPS resin to a specified amount of water and acid, heating and stirring in a pressure vessel, or by continuously performing the acid treatment. The method for separating the aqueous solution and PPS resin from the treated solution after acid treatment is relatively simple: filtration using a sieve or filter, such as natural filtration, pressure filtration, vacuum filtration, or centrifugal filtration. To remove residual acid or impurities from the surface of the PPS resin separated from the treated solution, it is preferable to wash it several times with water or warm water. Examples of washing methods include filtering while simultaneously pouring water onto the PPS resin in the filter, or filtering again after adding the separated PPS resin to pre-prepared water to separate the aqueous solution and PPS resin. Distilled water or deionized water is preferred for washing.

[0072] [Post-processing steps (hot water treatment)]

[0073] In this invention, hot water treatment is preferably performed before the acid treatment step, and the method is as follows. The water used in the hot water treatment of this invention is preferably distilled water or deionized water. The temperature of the hot water treatment is preferably 80–250°C, more preferably 120–200°C, and even more preferably 150–200°C. By setting the temperature to 80°C or higher, the hot water treatment effect can be obtained, and the amount of volatile gas generated can be suppressed. By setting the temperature to 250°C or lower, pressure rise can be suppressed, thus it is preferred from a safety perspective.

[0074] The preferred hot water treatment time is the time required for sufficient extraction of PPS resin and hot water. When treating at 80°C, the preferred time is 2 to 24 hours, and when treating at 200°C, the preferred time is 0.01 to 5 hours.

[0075] Regarding the ratio of PPS resin to water in hot water treatment, it is preferable to perform the treatment while the PPS resin is fully immersed in the water. The preferred water volume is 0.5 to 500 L relative to 500 g of PPS resin, more preferably 1 to 100 L, and even more preferably 2.5 to 20 L. By using 0.5 L or more water relative to 500 g of PPS resin, the PPS resin is fully immersed in the water, thus suppressing poor cleaning and preventing an increase in the generation of volatile gases, which is therefore preferable. Furthermore, by using less than 500 L of water relative to 500 g of PPS resin, the water will not become excessively abundant relative to the PPS resin, and production efficiency will not decrease significantly, which is also preferable.

[0076] There are no particular restrictions on the operation of these hot water treatments. They can be carried out by adding a specified amount of PPS resin to a specified amount of water, heating and stirring in a pressure vessel, or by continuously performing hot water treatment. There are no particular restrictions on the method for separating the aqueous solution and PPS resin from the treated solution after hot water treatment, but filtration using a sieve or filter is relatively simple; examples include natural filtration, pressure filtration, vacuum filtration, and centrifugal filtration. To remove residual impurities on the surface of the PPS resin separated from the treated solution, it is preferable to wash it several times with water or warm water. There are no particular restrictions on the washing method; examples include filtering while pouring water onto the PPS resin in the filter device, or filtering again after adding the separated PPS resin to pre-prepared water. Distilled water or deionized water is preferred for washing.

[0077] Furthermore, since the decomposition of the PPS terminal groups is not expected during these acid or hot water treatments, it is preferable to perform the acid or hot water treatments under an inactive atmosphere. Examples of inactive atmospheres include nitrogen, helium, and argon, but from an economic point of view, a nitrogen atmosphere is preferred.

[0078] [Post-processing steps (cleaning using organic solvents)]

[0079] In this invention, a cleaning step using an organic solvent may be included before the acid treatment or hot water treatment step, and the method is as follows. The organic solvent used for cleaning PPS resin in this invention is not particularly limited as long as it does not decompose PPS resin. Examples include nitrogen-containing polar solvents such as N-methyl-2-pyrrolidone, dimethylformamide, dimethylacetamide, 1,3-dimethylimidazolium ketone, hexamethylphosphoric triamine, and piperazine ketones; sulfoxide and sulfone solvents such as dimethyl sulfoxide, dimethyl sulfone, and sulfolane; and ketones such as acetone, methyl ethyl ketone, diethyl methyl ketone, and acetophenone. This includes solvents such as dimethyl ether, dipropyl ether, dioxane, tetrahydrofuran, and other ether-based solvents; chloroform, dichloromethane, trichloroethylene, dichloroethylene, perchloroethylene, monochloroethane, dichloroethane, tetrachloroethane, perchloroethane, chlorobenzene, and other halogen-based solvents; methanol, ethanol, propanol, butanol, pentanol, ethylene glycol, propylene glycol, phenol, cresol, polyethylene glycol, polypropylene glycol, and other alcohol / phenol-based solvents; and aromatic hydrocarbon solvents such as benzene, toluene, and xylene. Among these organic solvents, N-methyl-2-pyrrolidone, acetone, dimethylformamide, and chloroform are particularly preferred. Furthermore, one or more of these organic solvents may be used, or a mixture of two or more may be used.

[0080] Cleaning methods utilizing organic solvents include impregnating PPS resin in the solvent, with stirring or heating as needed. There are no particular restrictions on the cleaning temperature when cleaning PPS resin with organic solvents; a temperature range of approximately 300°C to room temperature is preferred. Higher cleaning temperatures tend to result in higher cleaning efficiency, but generally, a cleaning temperature of room temperature to 150°C is sufficient to achieve adequate results. Cleaning can also be performed in a pressure vessel under pressure at a temperature above the boiling point of the organic solvent. Furthermore, there are no particular restrictions on the cleaning time. It varies depending on the cleaning conditions; in batch cleaning, a cleaning time of 5 minutes or more is usually sufficient to achieve adequate results. Continuous cleaning is also possible.

[0081] These acid treatments, hot water treatments, and cleanings using organic solvents can also be combined appropriately.

[0082] [Post-processing steps (thermal oxidation treatment)]

[0083] The PPS resin used in this invention is preferably a PPS resin obtained by thermal oxidation treatment after the above-mentioned acid treatment, hot water treatment, or cleaning with an organic solvent. Thermal oxidation treatment refers to heating the PPS resin in an oxygen atmosphere or heating it with the addition of a peroxide such as H2O2 or a vulcanizing agent such as S. However, for the sake of simplicity, heating in an oxygen atmosphere is particularly preferred.

[0084] The heating device used for the thermal oxidation treatment of PPS resin can be a conventional hot air dryer, or a rotary or stirring device. However, for efficient and more uniform processing, a rotary or stirring device is preferred. The oxygen concentration in the atmosphere during thermal oxidation treatment is preferably 1% by volume or more, more preferably 2% by volume or more. To achieve the effects of the present invention, the upper limit of the oxygen concentration is preferably 5% by volume or less. By performing thermal oxidation treatment with an oxygen concentration of 5% by volume or less, the thermal oxidation treatment is not overdone, and the toughness of the molded article containing the thermally oxidized PPS resin is not impaired. On the other hand, by performing thermal oxidation treatment with an oxygen concentration of 1% by volume or more, sufficient thermal oxidation treatment can be performed, resulting in PPS resin with low volatile components, which is therefore preferred.

[0085] The preferred thermal oxidation temperature for PPS resin is 160–270°C, more preferably 160–230°C. Performing thermal oxidation at temperatures below 270°C prevents the process from proceeding rapidly and avoids compromising the toughness of molded articles containing the thermally oxidized PPS resin, thus this is preferable. On the other hand, performing thermal oxidation at temperatures above 160°C allows for a suitable rate of oxidation, resulting in PPS resin with low volatile component generation, which is also preferable.

[0086] The processing time for thermal oxidation is preferably 0.5 to 30 hours, more preferably 0.5 to 25 hours, and even more preferably 2 to 20 hours. A processing time of 0.5 hours or more allows for sufficient thermal oxidation, resulting in PPS resin with low volatile content, and is therefore preferred. A processing time of 30 hours or less allows for control of the cross-linking reaction caused by thermal oxidation, preventing damage to the toughness of molded articles containing thermally oxidized PPS resin, and is therefore preferred.

[0087] The lower limit of the melt flow rate (measured according to ASTM D-1238-70, at a temperature of 315.5°C and a load of 5000g) of the PPS resin preferred for use in this invention is preferably 100g / 10min or more, more preferably 300g / 10min or more. The upper limit is preferably 5000g / 10min or less, more preferably 3000g / 10min or less. A melt flow rate of 100g / 10min or more results in a PPS resin with excellent moldability, while a melt flow rate of 5000g / 10min or less results in a PPS resin with excellent mechanical strength, and is therefore preferred.

[0088] The PPS resin used in this invention is preferably dissolved in 20 times its mass of 1-chloronaphthalene at 250°C for 5 minutes, and the residue amount after hot-pressurized filtration using a PTFE membrane filter with a pore size of 1 μm is 4.0% by mass or less. A residue amount greater than 4.0% by mass indicates excessive thermal oxidative crosslinking of the PPS resin, resulting in increased gelling agents in the resin. A residue amount of 4.0% by mass or less inhibits the thermal oxidative crosslinking of the PPS resin, maintains its toughness, and preserves its resistance to thermal shock, making it preferable. There is no particular limitation on the lower limit of the residue amount, but 1.5% by mass or more is preferred, and 1.7% by mass or more is more preferable. A residue amount of 1.5% by mass or more represents a state of moderate thermal oxidative crosslinking, where the volatile components during melting are not significantly reduced, and the effect of reducing volatile components may be small.

[0089] Furthermore, the aforementioned residue amount was determined using a high-temperature filtration apparatus and an SUS test tube equipped with a pressure-sealed cap and a collection funnel, with a PPS resin membrane of approximately 80 μm thickness pressed into a membrane as the sample. Specifically, a membrane filter with a pore size of 1 μm was first placed on an SUS test tube, and then approximately 80 μm thick PPS resin membrane and 20 times the mass of 1-chloronaphthalene were weighed and sealed. The tube was placed in a high-temperature filtration apparatus at 250°C and heated and shaken for 5 minutes. Then, an air-containing syringe was connected to the pressure-sealed cap, and the syringe plunger was pushed out to perform air-pressure-based hot filtration. As a specific quantitative method for the residue amount, the difference between the mass of the membrane filter before filtration and the mass of the membrane filter after filtration and vacuum drying at 150°C for 1 hour was calculated relative to the input mass of the pressed PPS resin.

[0090] (B) Elastomer

[0091] The polyphenylene sulfide resin composition used in this invention contains (B) elastomer. As a lower limit for the amount of (B) elastomer, from the viewpoint of improving toughness and resistance to thermal shock after impregnation with a cooling medium, it is preferably 1 part by weight or more, more preferably 3 parts by weight or more, and most preferably 6 parts by weight or more, relative to 100 parts by weight of (A) polyphenylene sulfide resin. As an upper limit, from the viewpoint of flame retardancy, it is preferably less than 20 parts by weight, more preferably 14 parts by weight or less, and most preferably 10 parts by weight or less, relative to 100 parts by weight of (A) polyphenylene sulfide resin.

[0092] As the elastomer (B) in this invention, from the viewpoint of resistance to thermal shock after impregnation in a cooling medium, it is preferable to blend (B-1) with an epoxy group-containing olefin copolymer.

[0093] As (B-1) epoxy-based olefin copolymers, they can be obtained by introducing epoxy-based monomer components (including functional group components) into "polymers obtained by polymerizing α-olefins such as ethylene, propylene, 1-butene, 1-pentene, 1-octene, 4-methyl-1-pentene, isobutene, etc., individually or by polymerizing two or more of them", or "polymers 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, butyl methacrylate, etc., such as ethylene / propylene copolymers (" / " indicates copolymerization, the same applies below), ethylene / 1-butene copolymers, ethylene / 1-hexene, ethylene / 1-octene, ethylene / methyl acrylate copolymers, ethylene / ethyl acrylate copolymers, ethylene / butyl acrylate copolymers, ethylene / methyl methacrylate copolymers, ethylene / ethyl methacrylate copolymers, ethylene / butyl methacrylate copolymers, etc." Examples of functionalized components include epoxy-containing monomers such as glycidyl acrylate, glycidyl methacrylate, ethyl glycidyl acrylate, itaconic acid glycidyl acrylate, and citraconic acid glycidyl acrylate. There are no particular limitations on the methods for introducing these functionalized components; they can be copolymerized during the copolymerization of olefin-based copolymers or grafted into olefin-based copolymers using free radical initiators. Particularly useful examples of epoxy-containing olefin copolymers obtained by introducing functionalized components into olefin-based copolymers include ethylene / propylene-g-glycidyl methacrylate copolymers ("g" indicates graft polymerization, the same applies hereinafter), ethylene / 1-butene-glycidyl methacrylate copolymers, ethylene / glycidyl acrylate copolymers, ethylene / glycidyl methacrylate copolymers, ethylene / methyl acrylate / glycidyl methacrylate copolymers, and ethylene / methyl methacrylate / glycidyl methacrylate copolymers. Alternatively, epoxy-containing olefin copolymers, in addition to glycidyl esters of α-olefins such as ethylene and propylene and α,β-unsaturated acids, are preferred.

[0094] In (B-1) olefin copolymers with epoxy groups, from the viewpoint of improving toughness and resistance to thermal shock after being treated in a cooling medium, olefin copolymers containing glycidyl esters derived from α,β-unsaturated acids are preferred, and ethylene / methyl acrylate / glycidyl methacrylate copolymers are even more preferred.

[0095] As a lower limit for the amount of the epoxy-based olefin copolymer (B-1) to be blended, from the viewpoint of obtaining resistance to thermal shock after impregnation treatment in a cooling medium, it is preferably 0.1 parts by mass or more, more preferably 1 part by mass or more, and even more preferably 2 parts by mass or more, relative to 100 parts by mass of polyphenylene sulfide resin (A). As an upper limit for the amount of the epoxy-based olefin copolymer (B-1) to be blended, from the viewpoint of obtaining flame retardancy, it is preferably less than 9 parts by mass, more preferably 7 parts by mass or less, and even more preferably 5 parts by mass or less, relative to 100 parts by mass of polyphenylene sulfide resin (A).

[0096] Furthermore, using (B) an elastomer in combination with (B-1) an olefin copolymer having epoxy groups and (B-2) an elastomer without polar functional groups is preferred in terms of obtaining excellent moldability and superior resistance to thermal shock. There are no particular limitations on their ratio, but in terms of the mass ratio of their respective mixing amounts relative to 100 parts by mass of (A) polyphenylene sulfide resin, (B-1) / (B-2) = 5 / 95 to 95 / 5 is preferred, and in the range of (B-1) / (B-2) = 10 / 90 to 90 / 10, it is even more preferred because of the excellent balance between moldability and resistance to thermal shock after immersion in a cooling medium.

[0097] On the other hand, as an elastomer (B-2) that does not have polar functional groups, a copolymer of the same type as the olefin copolymer constituting (B-1) which has epoxy groups is preferred. Among these, from the viewpoint of resistance to thermal shock after being treated with a cooling medium, an ethylene / butyl acrylate copolymer is preferred.

[0098] (C) Fibrous filler

[0099] The polyphenylene sulfide resin composition used in this invention contains (C) a fibrous filler. Examples of fibrous fillers include glass fibers, ground glass fibers, carbon fibers, irregularly shaped glass fibers, glass-cut fibers, stainless steel fibers, aluminum fibers, or brass fibers, as well as organic fibers such as aromatic polyamide fibers or aramid Kevlar (registered trademark) fibers, gypsum fibers, ceramic fibers, asbestos fibers, zirconium oxide fibers, alumina fibers, silica fibers, titanium dioxide fibers, silicon carbide fibers, carbon nanotubes, carbon nanofibers, and cellulose nanofibers.

[0100] In (C) the fibrous filler, from the viewpoint of mechanical strength and resistance to thermal shock after impregnation in a cooling medium, at least one selected from glass fiber and shaped cross-section glass fiber is preferred. Specifically, shaped cross-section glass fiber is most preferred from the viewpoint of suppressing the anisotropy of strength during thermal shock by reducing the ratio of tensile strength (MD) in the resin flow direction and tensile strength (TD) perpendicular to the resin flow direction in the molded article, i.e., MD / TD. Shaped cross-section glass fiber is glass fiber with a flat cross-section. In the cross-section where the glass fiber is cut perpendicular to its length direction, the ratio of the major axis (the longest straight distance in the cross-section) to the minor axis (the longest straight distance in the direction perpendicular to the major axis) (major axis / minor axis, hereinafter sometimes simply referred to as the flatness ratio) is preferably 1.3 or more and 10 or less. Preferably 1.5 or more and 7 or less, and more preferably 1.5 or more and 5 or less. If the flatness ratio is 1.3 or higher, the resin composition exhibits good resistance to thermal shock; if it is 10 or lower, the resin composition exhibits good mechanical strength. Furthermore, the flatness ratio is determined by observing the cross-sections of 50 randomly selected glass fibers using a scanning electron microscope, measuring their major and minor axes, calculating their ratios, and then averaging these ratios.

[0101] The fibrous filler (C) used in this invention is preferably treated with a slugging agent or a surface treatment agent. Examples of slugging agents or surface treatment agents include functional compounds such as epoxy compounds, isocyanate compounds, silane compounds, and titanate compounds. From the viewpoint of improving the reactivity of the fibrous filler and suppressing the strength reduction caused by the impregnation treatment with the cooling medium, epoxy compounds with a high epoxy group content are particularly preferred.

[0102] As a lower limit for the amount of the fibrous filler (C) in this invention, from the viewpoint of mechanical strength and resistance to thermal shock after impregnation with a cooling medium, it is preferably 60 parts by mass or more, more preferably more than 80 parts by mass, and most preferably 100 parts by mass or more, relative to 100 parts by mass of polyphenylene sulfide resin (A). As an upper limit, from the viewpoint of flame retardancy, it is preferably 150 parts by mass or less, and more preferably 130 parts by mass or less, relative to 100 parts by mass of polyphenylene sulfide resin (A).

[0103] (D) Non-fibrous filler

[0104] The polyphenylene sulfide resin composition used in this invention incorporates a (D) non-fibrous filler. As the (D) non-fibrous filler, silicates such as fullerene, talc, wollastonite, zeolite, sericite, mica, kaolin, clay, pyrophyllite, bentonite, asbestos, and aluminosilicates can be used; metal compounds such as silicon oxide, magnesium oxide, aluminum oxide, zirconium oxide, titanium oxide, and iron oxide can be used; carbonates such as calcium carbonate, magnesium carbonate, and dolomite can be used; sulfates such as calcium sulfate and barium sulfate can be used; and glass microspheres, glass flakes, glass powder, ceramic microspheres, boron nitride, silicon carbide, carbon black, silica, and graphite can be used. These can be hollow, and two or more of these non-fibrous fillers can be used in combination. Furthermore, these non-fibrous fillers can also be used after pretreatment with coupling agents such as isocyanate compounds, organosilane compounds, organotitanate compounds, organoborane compounds, and epoxy compounds.

[0105] From the perspective of mechanical strength and resistance to thermal shock after being treated with a cooling medium, calcium carbonate is preferred.

[0106] From the viewpoint of flame retardancy and resistance to tracking, the lower limit of the mixing amount of the (D) non-fibrous filler used in this invention is preferably 40 parts by weight or more, more preferably 60 parts by weight or more, relative to 100 parts by weight of the (A) polyphenylene sulfide resin. As an upper limit, from the viewpoint of mechanical strength and resistance to thermal shock after impregnation with a cooling medium, it is preferably 140 parts by weight or less, more preferably 110 parts by weight or less, relative to 100 parts by weight of the (A) polyphenylene sulfide resin.

[0107] [Other Additives]

[0108] Furthermore, without impairing the effects of the present invention, silane compounds may be added to the PPS resin composition used in the present invention to improve mechanical strength, toughness, etc. Examples of silane compounds include isocyanate-containing alkoxysilane compounds such as γ-isocyanate-propyltriethoxysilane, γ-isocyanate-propyltrimethoxysilane, γ-isocyanate-propylmethyldimethoxysilane, γ-isocyanate-propylmethyldiethoxysilane, γ-isocyanate-propylethyldimethoxysilane, γ-isocyanate-propylethyldiethoxysilane, and γ-isocyanate-propyltrichlorosilane, as well as γ-epoxypropoxypropyl... Silane compounds including trimethoxysilane, γ-epoxypropoxypropyltriethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and other epoxy-containing alkoxysilane compounds; γ-(2-aminoethyl)aminopropylmethyldimethoxysilane, γ-(2-aminoethyl)aminopropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, and other amino-containing alkoxysilane compounds; and modified silicone oils having epoxy, amino, isocyanate, or hydroxyl groups. Among these, alkoxysilanes having epoxy, amino, isocyanate, or hydroxyl groups are particularly preferred for achieving excellent mechanical strength and resistance to thermal shock. The suitable addition amount of the above-mentioned silane compounds relative to 100 parts by weight of (A) PPS resin is preferably in the range of 0.05 to 3 parts by weight.

[0109] Furthermore, the PPS resin composition used in this invention can also be further mixed with other resins without impairing the effects of this invention. There are no particular limitations on the miscible resins; specific examples include polyamides, polyethylene terephthalate, polyetheretherketone resins, and vinyl aromatic compound block copolymers.

[0110] Furthermore, in order to maintain high heat resistance and thermal stability, the PPS resin composition of the present invention preferably incorporates one or more antioxidants selected from phenolic and phosphorus-based compounds, without impairing the effects of the present invention. From the viewpoint of improving heat resistance, the amount of this antioxidant is preferably 0.01 parts by mass or more, particularly preferably 0.02 parts by mass or more, relative to 100 parts by mass of (A) PPS resin. From the viewpoint of reducing the gas composition generated during molding, it is preferably 5 parts by mass or less, particularly preferably 1 part by mass or less. In addition, the use of both phenolic and phosphorus-based antioxidants greatly enhances the retention of heat resistance and thermal stability, and is therefore particularly preferred.

[0111] [Method for preparing PPS resin composition]

[0112] There are no particular limitations on the method for preparing the PPS resin composition in this invention. Representative examples include feeding the raw materials into a commonly known melt mixer such as a single-screw or twin-screw extruder, a Banbury mixer, a kneader, and a mixing roller, and mixing them at a temperature of 280–380°C. There are also no particular limitations on the mixing order of the raw materials. Any method can be used, such as mixing all the raw materials and then melt-mixing them as described above; mixing a portion of the raw materials and then melt-mixing them as described above, followed by melting-mixing the remaining raw materials; or mixing a portion of the raw materials and then using a side feeder to mix the remaining raw materials during melt-mixing in a single-screw or twin-screw extruder. Furthermore, for small amounts of additive components, other components can be mixed and granulated using the methods described above, and then added before molding.

[0113] The PPS resin composition obtained in this way can be used for various molding processes such as injection molding, extrusion molding, blow molding, and transfer molding, but it is particularly suitable for injection molding.

[0114] [Molded articles formed from PPS resin compositions]

[0115] The tensile modulus of elasticity of the molded articles formed from the PPS resin composition of the present invention, as determined according to ISO 527-1,-2 (2012), must be between 10 GPa and 21 GPa. In this way, even molded articles of the PPS resin composition that have been impregnated in a cooling medium exhibit excellent resistance to thermal shock and can be used for products with complex shapes that are prone to breakage, such as motor parts.

[0116] The lower limit of the tensile modulus of elasticity must be 10 GPa or higher, preferably 12 GPa or higher, and more preferably 16 GPa or higher. Below 10 GPa, rigidity tends to decrease during impregnation in a cooling medium, and the difference in linear expansion coefficients with the metal tends to increase, leading to a decrease in resistance to thermal shock after impregnation in the cooling medium. The upper limit of the tensile modulus of elasticity must be 21 GPa or lower, preferably 20 GPa or lower. If it exceeds 21 GPa, the toughness after impregnation in the cooling medium is insufficient, and the resistance to thermal shock deteriorates.

[0117] To achieve a tensile modulus of elasticity of 10 GPa or higher for the molded article formed from the PPS resin composition of the present invention, this can be achieved by blending (C) a fibrous filler or (D) a non-fibrous filler that has a high rigidity-enhancing effect into (A) the PPS resin, or by reducing the amount of highly flexible thermoplastic resin other than (A) the PPS resin. To achieve a tensile modulus of elasticity of 21 GPa or lower for the molded article formed from the PPS resin composition of the present invention, this can be achieved by blending (B) an elastomer with a low tensile modulus of elasticity into (A) the PPS resin, or by not excessively blending (C) a fibrous filler or (D) a non-fibrous filler that has high rigidity.

[0118] The molded article formed from the PPS resin composition of the present invention, wherein the tensile strength in the resin flow direction is denoted as MD and the tensile strength in the direction perpendicular to the resin flow direction is denoted as TD, has an MD of at least 70 MPa and a MD / TD ratio of at least 1.4. In this way, a high tensile strength can be maintained even after impregnation with a cooling medium, the anisotropy of strength during thermal shock is suppressed by reducing the MD / TD ratio, and the cooling medium is difficult to penetrate between the metal and resin even after impregnation, resulting in excellent resistance to thermal shock.

[0119] Regarding the lower limit of MD, MD must be above 70 MPa, preferably above 80 MPa. Below 70 MPa, the tensile strength decreases after impregnation in the cooling medium, resulting in reduced resistance to thermal shock. There is no particular upper limit to MD; the higher the MD after impregnation in the cooling medium, the better the resistance to thermal shock.

[0120] Regarding the lower limit of TD, TD is preferably 60 MPa or more, and more preferably 80 MPa or more. By setting it to 60 MPa or more, the decrease in tensile strength after impregnation in the cooling medium can be suppressed, and the resistance to thermal shock after impregnation in the cooling medium can be maintained, so it is preferred.

[0121] There is no particular limitation on the lower limit of MD / TD (the ratio of MD to TD). Generally, molded articles tend to have MD greater than TD, but in cases where the molded article has thickness, or where the orientation of the glass fiber can easily become random, TD may sometimes be greater than MD. In practice, the lower limit of MD / TD is preferably 0.7 or higher. The upper limit of MD / TD must be 1.4 or lower, preferably 1.2 or lower. When MD / TD is greater than 1.4, the anisotropy of strength during thermal shock increases, and after impregnation in a cooling medium, the cooling medium can easily penetrate between the metal and resin, reducing thermal shock resistance. Furthermore, the closer MD / TD is to 1, the better, with 1 being the most preferred. When MD / TD is 1, it can be considered a state without anisotropy.

[0122] To achieve a mechanical strength of MD of 70 MPa or higher, one can mix (C) fibrous fillers that have a high mechanical strength-enhancing effect with (A) PPS resin, or not mix too many thermoplastic resins with weak mechanical strength other than (A) PPS resin, or use non-fibrous fillers such as calcium carbonate, which does not easily impair mechanical strength, as (D) non-fibrous fillers.

[0123] The reason for the increased MD / TD is that by blending (C) fibrous filler into (A) PPS resin, the fibrous filler tends to orient itself in the resin flow direction. However, if (C) fibrous filler is not blended, the mechanical strength decreases. To achieve an MD / TD of 1.4 or less, in addition to using (C) fibrous filler, (D) non-fibrous filler with a small anisotropy ratio, such as calcium carbonate, can be used in (A) PPS resin. Alternatively, (C) fibrous filler that does not cause excessive anisotropy can be used. Or, fibrous filler with a high anisotropy-suppressing effect, such as irregularly shaped glass fiber, can be used as (C) fibrous filler.

[0124] Through this invention, even after the molded articles formed from the polyphenylene sulfide resin composition are immersed in a cooling medium and subjected to heat treatment, they exhibit excellent resistance to thermal shock, revealing a previously unknown property. Furthermore, it has been discovered that the molded articles formed from the PPS resin composition can be used in a new application for motor components that utilize a cooling medium.

[0125] Furthermore, the present invention relates to a method for molding a PPS resin composition, which is a mixture of PPS resin, elastomer, fibrous filler and non-fibrous filler, into a molded article. The molded article has a tensile modulus of elasticity of 10 GPa or more and 21 GPa or less. When the tensile strength of the molded article in the resin flow direction is denoted as MD and the tensile strength in the direction perpendicular to the resin flow direction is denoted as TD, MD is 70 MPa or more and the ratio of MD to TD, i.e., MD / TD, is 1.4 or less. This method is for forming a motor component that uses a cooling medium.

[0126] [Cooling medium]

[0127] The cooling medium used in motor components is crucial for improving motor drive efficiency by cooling the motor and preventing a reduction in motor lifespan. The cooling medium used in the motor components of this invention preferably comprises at least one selected from long-life coolant (LLC), ethylene glycol, oil, and water, more preferably oil. The use of oil as a cooling medium also includes cases where water has been unintentionally mixed in. Oil has a higher volume resistivity than long-life coolant (LLC) and water, and exhibits excellent insulation properties. In particular, cooling oil for EVs, compared to conventional ATF oils, has superior insulation properties and excellent corrosion inhibition of metals. Therefore, it can be used not only for drive motors but also for cooling batteries and inverters, thus reducing the variety of cooling media, simplifying thermal management, reducing the number of components, and achieving weight reduction. Oils with a resistivity of 30 MΩ·m or higher, measured at 90°C according to IEC 60247, exhibit excellent insulation properties and are preferred for suppressing the deterioration of motor components. Furthermore, oils with a thermal conductivity of 0.1 W / m·K or higher, measured at 80°C according to ASTM D2717, are preferred as they effectively cool components. Among these, e-Axle-specific oils developed specifically for e-Axle are preferred. Commercially available oils for EVs, such as those from CASTROL under the trade name BOT805CEV, have lower viscosity and better flowability compared to general ATF oils, thus improving motor cooling performance more effectively, and exhibiting excellent corrosion resistance and insulation properties for copper components.

[0128] As a heat treatment method after immersion in a cooling medium, it is preferable to subject the motor components to a durability test for 2000 hours in an environment with an upper limit of 150°C.

[0129] The molded articles formed from the PPS resin composition of the present invention preferably exhibit excellent resistance to thermal shock after being impregnated with a cooling medium in the thin-walled and corner portions. In thermal shock tests, stress tends to concentrate in the thin-walled and corner portions due to the difference in the coefficients of linear expansion between the resin and the metal. Furthermore, the cooling medium easily penetrates between the resin and the metal, resulting in poor thermal shock resistance after impregnation in the cooling medium. Molded articles formed from the PPS resin composition exhibiting excellent thermal shock resistance after impregnation in a cooling medium in the thin-walled and corner portions are also suitable for motor components used in a wide temperature range from low to high temperatures, or for motor components containing thin-walled portions for weight reduction. To achieve excellent thermal shock resistance in the thin-walled and corner portions after impregnation in a cooling medium, it is necessary to mold the articles formed from the polyphenylene sulfide resin composition of the present invention. In this way, the strength reduction caused by the impregnation treatment of the cooling medium can be suppressed. In addition, by suppressing the anisotropy of strength during thermal shock, even after impregnation treatment in the cooling medium, the cooling medium is difficult to penetrate between the metal and the resin, resulting in excellent resistance to thermal shock.

[0130] The molded articles formed from the PPS resin composition of the present invention preferably exhibit V-0 flame retardancy after impregnation in a cooling medium, i.e., flame retardancy as determined by UL94 when the sample thickness is 0.7 mm or less. In this way, the molded articles formed from the PPS resin composition can also be applied to motor components that require flame retardancy and include thin-walled sections for weight reduction, and which come into contact with a cooling medium. To achieve V-0 flame retardancy after impregnation in a cooling medium when the sample thickness is 0.7 mm or less, the amount of the (D) non-fibrous filler (a non-combustible component) can be increased, or the amount of the (B) elastomer (a combustible component) can be decreased; however, it is preferable to maintain the degree to which the resistance to thermal shock after impregnation in a cooling medium does not decrease.

[0131] The molded articles formed from the PPS resin composition of this invention preferably exhibit tracking resistance of 175V or higher after impregnation in a cooling medium, i.e., tracking resistance as measured according to IEC 60112 (2003). IEC 60664 states that for products such as automotive parts, it is undesirable to use materials with tracking resistance less than 175V in areas where the product's rated voltage is greater than 630V and the pollution level is 3 (these should be considered). Therefore, molded articles formed from resin compositions with tracking resistance of 175V or higher after impregnation in a cooling medium can also be applied to motor components that are subjected to high voltage and are in contact with a cooling medium. In order to exhibit tracking resistance of 175V or higher after impregnation in a cooling medium, the amount of polyphenylene sulfide resin, which has low tracking resistance, can be reduced. A large amount of (C) fibrous filler and (D) non-fibrous inorganic filler can be mixed in, but preferably to the extent that the thermal shock resistance after impregnation in a cooling medium is not reduced.

[0132] Furthermore, the present invention is intended for use in motor components that utilize a cooling medium, and is described as follows: "a molded article formed from a PPS resin composition of PPS resin, elastomer, fibrous filler and non-fibrous filler" and "a molded article having a tensile modulus of 10 GPa or more and 21 GPa or less, wherein the tensile strength in the resin flow direction of the molded article is denoted as MD and the tensile strength in the direction perpendicular to the resin flow direction is denoted as TD, and the MD is 70 MPa or more, and the ratio of MD to TD, i.e., MD / TD, is 1.4 or less".

[0133] The molded articles formed from the PPS resin composition of this invention exhibit excellent resistance to thermal shock after being impregnated in a cooling medium, making them suitable for motor components using cooling media that can be used even in harsh environments involving contact with the cooling medium. As motor components, suitable options include stators, rotors, slip rings, current sensors, busbars, rotation angle sensors, cooling medium flow lines, and cooling medium spray components. In particular, due to their excellent resistance to thermal shock after impregnation in a cooling medium, they are excellent for use as injection-molded motor components with metal inserts. Furthermore, as components designed for weight reduction, motor components with a minimum thickness of 0.7 mm or less in the molded articles formed from the PPS resin composition are preferred.

[0134] As applicable uses of the molded articles formed from the PPS resin composition in this invention, they can be used in electrical and electronic components such as sensors, LED lights, civilian connectors, sockets, resistors, relay boxes, switches, coil frames, capacitors, variable capacitor boxes, oscillators, various terminal boards, transformers, plugs, printed circuit boards, tuners, speakers, microphones, headphones, small motors, magnetic head bases, semiconductor devices, liquid crystal devices, floppy disk drive carriages, floppy disk drive racks, motor brush holders, parabolic antennas, and computer-related components; they can also be applied to household and office appliance components such as VTR (video recorder) components, television components, electric irons, hair dryers, rice cooker components, microwave oven components, audio components, audio equipment, and sound equipment components such as laser discs (registered trademarks) and optical discs, lighting components, refrigerator components, air conditioning components, typewriter components, and word processor components. In addition, preferred examples include mechanical components such as office computer components, telephone components, fax machine components, copier components, cleaning tools, lighters, and typewriters; optical equipment and precision mechanical components such as microscopes, binoculars, cameras, and clocks; water system accessories such as faucet valve cores, mixer taps, water pump accessories, pipe fittings, water flow regulating valves, pressure relief valves, hot water sensors, water flow sensors, and water meter housings; valve-type alternator terminals, alternator connectors, integrated circuit voltage regulators, potentiometer bases for vehicle headlight dimming, exhaust valves, and various other valves; fuel system, exhaust system, intake system pipes, intake manifolds, fuel pumps, engine coolant connectors, and carburetors. Main body, carburetor gasket, exhaust gas sensor, coolant sensor, oil temperature sensor, throttle position sensor, crankshaft position sensor, air flow meter, brake pad wear sensor, air conditioning thermostat base, heater air flow control valve, radiator motor brush holder, water pump impeller, water pump housing, engine cooling module, turbine blades, wiper motor related components, distributor, starter switch, starter relay, transmission wiring harness, windshield washer nozzle, air conditioning panel switch board, fuel solenoid valve coil, fuse connector, horn terminal block, electrical component insulation board, lamp holder, lamp reflector, lamp housing, brake piston, solenoid coil frame, oil filter, ignition device housing, vehicle speed sensor, cable sheath, and other automotive and vehicle-related components for various applications.

[0135] Example

[0136] The following examples illustrate the invention in more detail, but the invention is not limited to these examples.

[0137] [Evaluation method for PPS resin manufactured in the reference example]

[0138] (1) Melt Flow Rate (MFR)

[0139] The test was conducted at a temperature of 315.5℃ and a load of 5000g, in accordance with the method of ASTM-D1238-70.

[0140] (2) Residue amount

[0141] A pre-weighed PTFE membrane filter with a pore size of 1 μm was placed on a Censhu Scientific SUS test tube equipped with a pressure-sealed cap and a collection funnel. Approximately 100 mg of 80 μm thick, press-coated PPS resin and 2 g of 1-chloronaphthalene were added, and the tube was sealed. The tube was then inserted into a Censhu Scientific SSC-9300 high-temperature filtration apparatus and heated and shaken at 250°C for 5 minutes to dissolve the PPS resin in the 1-chloronaphthalene. A 20 mL syringe containing air was connected to the pressure-sealed cap, the stopcock was pushed out, and the solution was filtered through the membrane filter. The membrane filter was removed, vacuum-dried at 150°C for 1 hour, and then weighed. The difference in the mass of the membrane filter before and after filtration, relative to the mass of the press-coated PPS resin added, was taken as the residue amount (mass %).

[0142] [Reference Example] Preparation of PPS

[0143] 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 added to a 70°C high-pressure reactor equipped with a stirrer and a bottom stop valve. The reactor was slowly heated to 245°C over approximately 3 hours under normal pressure while nitrogen was introduced. After evaporating 14.78 kg of water and 0.28 kg of NMP, the reactor was cooled to 200°C. Including the water consumed in the hydrolysis of NMP, the residual water content of the system corresponding to 1 mole of alkali metal sulfide added was 1.06 moles. Additionally, the amount of hydrogen sulfide released corresponding to 1 mole of alkali metal sulfide added was 0.02 moles.

[0144] The system 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 a nitrogen atmosphere, and the mixture was stirred at 240 rpm while the temperature was increased from 200°C to 270°C at a rate of 0.6°C / min. After reacting at 270°C for 100 minutes, the bottom valve of the high-pressure reactor was opened, and the material in the reactor was flash-evaporated into a container equipped with a stirrer over a period of 15 minutes under nitrogen pressure. The mixture was then stirred at 250°C for a period of time to remove most of the NMP.

[0145] The obtained solids were added to a high-pressure reactor equipped with a stirrer along with 76 liters of deionized water and washed at 70°C for 30 minutes. The mixture was then filtered using a glass filter. Next, 76 liters of deionized water heated to 70°C were poured into the glass filter, and the mixture was filtered again to obtain a filter cake.

[0146] The resulting filter cake and 90 liters of deionized water were added to a high-pressure reactor equipped with a stirrer. Acetic acid was added to adjust the pH to 7. After purging the atmosphere inside the high-pressure reactor with nitrogen, the temperature was raised to 192°C and held for 30 minutes. The high-pressure reactor was then cooled, and the contents were removed.

[0147] The extracted material was filtered through a glass filter, and then 76 liters of deionized water at 70°C was injected and filtered again to obtain a filter cake. The obtained filter cake was placed in a nitrogen gas flow environment and dried at 120°C to obtain dried PPS.

[0148] The obtained PPS had a melt flow rate (MFR) of 600 g / 10 min and a residue of 0.7 g / min.

[0149] The following shows the raw materials used in the examples and comparative examples.

[0150] (A) PPS resin

[0151] PPS-1: The PPS resin obtained by polymerization according to the method described in the reference example was subjected to thermal oxidation treatment for 12 hours at an oxygen concentration of 2% and a temperature of 220°C. The resulting PPS had a melt flow rate of 400 g / 10 min and a residue of 1.9% by mass.

[0152] (B) Elastomer

[0153] B-1: Ethylene-glycidyl methacrylate-methyl acrylate copolymer (Sumitomo Chemical Co., Ltd. Bondfast 7M; ethylene 67% by mass, glycidyl methacrylate 6% by mass, methyl acrylate 27% by mass).

[0154] B-2: Ethylene-n-butyl acrylate copolymer (Lotryl 35BA40 manufactured by Arkema Corporation).

[0155] (C) Fibrous filler

[0156] C-1: Irregular cross-section glass fiber (T-760FGF manufactured by Nippon Electric Glass Co., Ltd., with a flatness ratio of 4).

[0157] C-2: Circular cross-section glass fiber (T-760H manufactured by Nippon Electric Glass Co., Ltd., with a flatness ratio of 1).

[0158] (D) Non-fibrous filler

[0159] D-1: Heavy calcium carbonate (Sankyo Flour Co., Ltd., Escalon #800).

[0160] D-2: Magnesium hydroxide (Kisuma5EU manufactured by Kyowa Chemical Industry Co., Ltd.)

[0161] [Test and evaluation methods for molded articles formed from resin compositions]

[0162] The testing and evaluation methods in this embodiment and comparative example are shown below.

[0163] (1) Tensile modulus of elasticity

[0164] Resin composition granules were fed into an injection molding machine (SE-50D) manufactured by Sumitomo Heavy Industries, Ltd., with the barrel temperature set at 310°C and the mold temperature set at 145°C. Evaluation test pieces were prepared by injection molding using an A1 type test piece mold conforming to ISO 20753 (2008), under a holding pressure of 75% of the filling pressure and a filling time of 0.8 seconds. The test pieces were conditioned for 16 hours at 23°C and 50% relative humidity. Then, the tensile modulus of elasticity was determined according to ISO 527-1,-2 (2012) under an atmosphere of 23°C and 50% relative humidity, with a fixture spacing of 115 mm and a test speed of 5 mm / min.

[0165] (2) Tensile strength in the flow direction (MD) and tensile strength perpendicular to the flow direction (TD)

[0166] A Sumitomo Heavy Industries, Ltd. injection molding machine (SE50DUZ-C160) with a barrel temperature set at 320°C and a mold temperature set at 130°C was used to feed resin composition granules into the machine. An 80mm × 80mm × 3.0mm thick square plate was produced by injection molding using a mold for a square plate with a filling time of 0.5 seconds and a holding pressure of 50% of the filling pressure. The square plate was then machined into Type 3 shapes conforming to ISO 8256, with the flow direction (injection molding direction) and the direction perpendicular to the resin flow direction as the long sides, respectively. Test specimens for tensile strength (MD) in the flow direction and tensile strength (TD) in the direction perpendicular to the flow direction were obtained. The specimens were conditioned for 16 hours at 23°C and 50% relative humidity, and then the tensile strength was measured at 23°C and 50% relative humidity under the following conditions: gauge length 10mm and test speed 1mm / min.

[0167] (3) Resistance to thermal shock after LLC impregnation treatment

[0168] A resin composition granule was fed into an injection molding machine (SE-50DUZ) manufactured by Sumitomo Heavy Industries, Ltd., with the barrel temperature set at 320°C and the mold temperature set at 130°C. A carbon steel S45C metal block was placed inside the mold, and injection molding was performed under the following conditions: injection speed of 100 mm / s, injection pressure reaching 5 MPa when filling to the front of the specimen, and injection time of 12 seconds, to obtain... Figure 1 The evaluation specimens shown are injection-molded metal inserts. These specimens were immersed in a 50% by mass aqueous solution of Toyota's original long-life coolant (S-LLC) diluted with distilled water in a pressure-resistant container and subjected to a heat treatment at 150°C for 2000 hours. The LLC-impregnated specimens were then treated at 130°C for 1 hour, followed by -40°C for 1 hour, constituting one cycle of thermal shock treatment. Every 10 cycles, visual inspection was performed to check for cracks. The thinnest part of the specimen has a wall thickness of 0.6 mm, and stress concentration is prone to occur at the corners; this specimen is used to simulate the thermal shock resistance of thin-walled and corner areas. The thermal shock resistance was evaluated by the number of cycles at which cracks appeared. A product level with no practical problems was considered to have more than 100 cycles without cracks; the more cycles the specimen underwent before cracks appeared, the better its thermal shock resistance, and the higher the priority.

[0169] (4) Resistance to thermal shock after oil immersion treatment

[0170] A resin composition granule was fed into an injection molding machine (SE-50DUZ) manufactured by Sumitomo Heavy Industries, Ltd., with the barrel temperature set at 320°C and the mold temperature set at 130°C. A carbon steel S45C metal block was placed inside the mold, and injection molding was performed under the following conditions: injection speed of 100 mm / s, injection pressure reaching 5 MPa when filling to the front of the specimen, and injection time of 12 seconds, to obtain... Figure 1 The evaluation specimen shown is an injection-molded metal insert. This specimen was immersed in electric vehicle (EV)-specific cooling oil (CASTROL BOT805CEV) in a pressure vessel and subjected to a 2000-hour heat treatment at 150°C. After oil immersion, the specimen was treated at 130°C for 1 hour, followed by -40°C for 1 hour, constituting one cycle for thermal shock testing. Every 10 cycles, the specimen was visually inspected for cracks. The thinnest part of the specimen has a wall thickness of 0.6 mm, and stress concentration is prone to occur at the corners; this specimen is used to simulate the thermal shock resistance of thin-walled sections and corners. The thermal shock resistance was evaluated by the number of cycles at which cracks appeared. A product level with no practical problems was considered to have more than 100 cycles without cracks; the more cycles the specimen underwent before cracks appeared, the better its thermal shock resistance, and the higher the priority.

[0171] (5) Flame retardancy after oil impregnation treatment

[0172] Resin composition granules were fed into an injection molding machine (SE-50D) manufactured by Sumitomo Heavy Industries, Ltd., with the barrel temperature set at 320°C and the mold temperature set at 145°C. Using a mold conforming to the UL94 specification for the UL test piece shape, injection molding was performed at an injection speed of 120 mm / s, an injection pressure reaching 5 MPa when filling to the front of the test piece, an injection time of 8 seconds, and a cooling time of 10 seconds to obtain an evaluation test piece. This test piece was then immersed in electric vehicle (EV)-specific cooling oil (CASTROL BOT805CEV) in a pressure vessel and subjected to a heat treatment at 150°C for 2000 hours. After oil immersion treatment, the test piece was evaluated for flame retardancy according to the UL94 vertical test. Flame retardancy was graded in the order of V-0 > V-1 > V-2, decreasing in intensity. If the V-2 rating could not be achieved, it was classified as "beyond V". The test used a specimen with a thickness of 0.7 mm. It is preferred that the specimen thickness is less than 0.7 mm to still achieve the V-0 rating.

[0173] (6) Resistance to tracking after oil immersion treatment

[0174] Resin composition granules were fed into an injection molding machine (SE50DUZ-C160) manufactured by Sumitomo Heavy Industries, Ltd., with the barrel temperature set at 320°C and the mold temperature set at 130°C. Using a mold for a square plate with a thickness of 80mm × 80mm × 3.0mm, injection molding was performed under conditions of a filling time of 0.5 seconds and a holding pressure of 50% of the filling pressure to obtain a square plate with a thickness of 80mm × 80mm × 3.0mm. This test piece was immersed in electric vehicle (EV)-specific cooling oil (CASTROL BOT805CEV) in a pressure-resistant container and subjected to a heat treatment at 150°C for 2000 hours. The maximum voltage at which the oil-immersed test piece did not exhibit tracking failure was measured according to IEC 60112 (2003), using a 0.1% ammonium chloride aqueous solution as the electrolyte. A higher maximum voltage indicates better tracking resistance; preferably 175V or higher.

[0175] [Examples 1-6, Comparative Examples 1-7]

[0176] A twin-screw extruder (TEM-26SS, Toshiba Machine Co., Ltd.) with a barrel temperature set at 320°C, a screw speed set at 400 rpm, and a 26 mm diameter intermediate feed port was used. To 100 parts by weight of (A) PPS resin, (B) elastomer and (D) non-fibrous filler were added from the feed port according to the mass ratios shown in Tables 1 and 2, bringing the mixture to a molten state. Then, (C) fibrous filler was added from the intermediate feed port according to the mass ratios shown in Tables 1 and 2. The mixture was melt-blended at a discharge rate of 30 kg / hour to obtain PPS resin composition granules. The aforementioned properties were evaluated using these PPS resin composition granules. The results are shown in Tables 1 and 2.

[0177]

[0178]

[0179] As can be seen from Examples 1 to 6, by mixing the components (A) to (D), the tensile modulus of the molded article is between 10 GPa and 21 GPa. When the tensile strength of the molded article in the resin flow direction is denoted as MD and the tensile strength in the direction perpendicular to the flow direction is denoted as TD, the MD is 70 MPa or more and the MD / TD ratio is 1.4 or less. After being impregnated in a cooling medium and heat-treated, the thermal shock resistance (more than 100 cycles) is excellent, making it suitable for use in motor components that use a cooling medium.

[0180] As can be seen from Comparative Examples 1 and 3, when MD / TD is greater than 1.4, the resistance to thermal shock after impregnation and heat treatment in the cooling medium is poor.

[0181] Comparative Example 2 shows that when the tensile modulus of elasticity is greater than 21 GPa and MD / TD is greater than 1.4, the resistance to thermal shock after impregnation and heat treatment in the cooling medium is poor.

[0182] Comparative Example 4 shows that when the tensile modulus of elasticity is less than 10 GPa and MD is less than 70 MPa, the resistance to thermal shock after impregnation and heat treatment in the cooling medium is poor.

[0183] Comparative Example 5 shows that when MD is less than 70 MPa and MD / TD is greater than 1.4, the resistance to thermal shock after impregnation and heat treatment in the cooling medium is poor.

[0184] Comparative Examples 6 and 7 show that when MD is less than 70 MPa, the resistance to thermal shock after impregnation and heat treatment in the cooling medium is poor.

[0185] Industry availability

[0186] Because it exhibits excellent resistance to thermal shock after being impregnated in the cooling medium without significantly compromising the inherent excellent flame retardant properties of polyphenylene sulfide resin, it is suitable for use in motor components that use cooling media, such as busbars with built-in metal inserts and current sensors, which are in contact with the cooling medium.

[0187] Explanation of symbols in attached drawings

[0188] 1. Metal inserts

[0189] 2. Gate

[0190] 3. Metal insert injection molded products

Claims

1. A motor component using a cooling medium, which is obtained by molding a polyphenylene sulfide resin composition containing (A) polyphenylene sulfide resin, (B) elastomer, (C) fibrous filler and (D) non-fibrous filler, wherein the molded article formed from the polyphenylene sulfide resin composition has a tensile modulus of 10 GPa or more and 21 GPa or less, and when the tensile strength of the molded article in the resin flow direction is denoted as MD and the tensile strength in the direction perpendicular to the resin flow direction is denoted as TD, MD is 70 MPa or more, and the ratio of MD to TD, i.e., MD / TD, is 1.4 or less.

2. The motor component using a cooling medium as claimed in claim 1, wherein the polyphenylene sulfide resin composition is mixed with an epoxy-based olefin copolymer (B-1) as the elastomer of (B), and the epoxy-based olefin copolymer (B-1) is mixed in at least 0.1 parts by weight and less than 9 parts by weight relative to 100 parts by weight of the polyphenylene sulfide resin (A).

3. The motor component using a cooling medium as described in claim 1 or 2, wherein the polyphenylene sulfide resin composition contains at least 60 parts by weight of (D) non-fibrous filler relative to 100 parts by weight of (A) polyphenylene sulfide resin.

4. The motor component using a cooling medium as described in claim 1 or 2, wherein the cooling medium comprises at least one selected from long-life coolant LLC, ethylene glycol, oil, and water.

5. The motor component using a cooling medium as described in claim 1 or 2, wherein the molded article formed from the polyphenylene sulfide resin composition is a molded article formed by injection molding with metal inserts.

6. The motor component using a cooling medium as described in claim 1 or 2, wherein the component is selected from a stator, rotor, slip ring, current sensor, busbar, rotation angle sensor, cooling medium flow line, and cooling medium spray component.

7. The motor component using a cooling medium as described in claim 1 or 2, wherein the thinnest part of the molded article formed from the polyphenylene sulfide resin composition is less than 0.7 mm.

8. The motor component using a cooling medium as described in claim 1 or 2, wherein the molded article formed from the polyphenylene sulfide resin composition has a MD and TD of 80 MPa or higher.

9. A method for molding a motor component using a cooling medium, comprising molding a polyphenylene sulfide resin composition containing (A) polyphenylene sulfide resin, (B) an elastomer, (C) a fibrous filler and (D) a non-fibrous filler to obtain a molded article, wherein the tensile modulus of elasticity of the molded article is 10 GPa or more and 21 GPa or less, and when the tensile strength of the molded article in the resin flow direction is denoted as MD and the tensile strength in the direction perpendicular to the resin flow direction is denoted as TD, MD is 70 MPa or more, and the ratio of MD to TD, i.e., MD / TD, is 1.4 or less.

10. A molded article for use in motor components using a cooling medium, said molded article being obtained by molding a polyphenylene sulfide resin composition containing (A) polyphenylene sulfide resin, (B) an elastomer, (C) a fibrous filler and (D) a non-fibrous filler, having a tensile modulus of elasticity of 10 GPa or more and 21 GPa or less, wherein when the tensile strength of the molded article in the resin flow direction is denoted as MD and the tensile strength in the direction perpendicular to the resin flow direction is denoted as TD, MD is 70 MPa or more, and the ratio of MD to TD, i.e., MD / TD, is 1.4 or less.

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