Fiber-reinforced thermoplastic resin composition and resin-metal composite

Abstract

A fiber-reinforced thermoplastic resin composition comprising: a thermoplastic resin composition; and glass fibers having a flat-shaped cross-section, wherein the thermoplastic resin composition contains 11.0-30.0 parts by mass of a bromine-based flame retardant and 100 parts by mass of a styrene-based resin composition comprising 75.0-94.0 parts by mass of a styrene-based polymer having a syndiotactic structure with a weight average molecular weight of less than 230,000 and 6.0-25.0 parts by mass of a rubber-like elastic body, and the amount of the glass fibers with respect to the total amount of the thermoplastic resin composition and the glass fibers is 25.0-55.0 mass%.

Description

Fiber-reinforced thermoplastic resin composition and resin-metal composite

[0001] The present invention relates to a fiber-reinforced thermoplastic resin composition and a resin-metal composite, and more particularly to a fiber-reinforced thermoplastic resin composition and a resin-metal composite containing a styrene-based resin composition.

[0002] Technologies for integrating dissimilar materials, such as metal and resin, have been developed, primarily in the fields of electronics and electromechanics, automobiles, and home appliances. Products in these fields are often used in harsh environments, such as being alternately exposed to high and low temperatures, depending on the usage situation and environment. Therefore, materials used in these fields are required to have durability, i.e., heat shock resistance, that prevents cracking and other damage even when exposed to alternate high and low temperatures. Furthermore, these materials are required to have flame retardancy to prevent ignition due to tracking or other causes during use.

[0003] For example, Patent Document 1 discloses a polyarylene sulfide resin composition obtained by blending a polyarylene sulfide resin, an epoxy resin, an epoxy-containing polyolefin, glass fibers, and glass flakes. Patent Document 2 discloses a polyester resin composition characterized by containing a polyalkylene terephthalate, glass fibers, an elastomer, a bromine-based flame retardant, an antimony compound, and a plasticizer containing an epoxy group and having a glass transition temperature of −50° C. or lower.

[0004] International Publication No. 2019 / 208377 Japanese Patent Application Laid-Open No. 2020-84002

[0005] However, the flame retardancy of the polyarylene sulfide resin composition of Patent Document 1 was not sufficiently studied, and it could not be said that both heat shock resistance and flame retardancy were sufficiently achieved. Furthermore, Patent Document 2 discloses that the flame retardancy of a polyester resin composition is improved by using a bromine-based flame retardant, but on the other hand, the heat shock resistance may be reduced, and it could not be said that both heat shock resistance and flame retardancy were sufficiently achieved.

[0006] The present invention aims to provide a fiber-reinforced thermoplastic resin composition that has excellent flame retardancy and also has excellent heat shock resistance when used as a resin member of a metal-resin composite, and a metal-resin composite using the same.

[0007] As a result of extensive research, the present inventors have found that the above-mentioned problems can be solved by a fiber-reinforced thermoplastic resin composition containing a thermoplastic resin composition including a styrene-based polymer having a specific syndiotactic structure and a rubber-like elastomer, glass fibers having a flat cross section, and a brominated flame retardant. That is, the present invention relates to the following [1] to [7].

[0008] [1] A fiber-reinforced thermoplastic resin composition comprising a thermoplastic resin composition and glass fibers having a flat cross section, wherein the thermoplastic resin composition comprises 100 parts by mass of a styrene-based resin composition consisting of 75.0 to 94.0 parts by mass of a styrene-based polymer having a syndiotactic structure and a weight-average molecular weight of less than 230,000 and 6.0 to 25.0 parts by mass of a rubber-like elastomer, and 11.0 to 30.0 parts by mass of a brominated flame retardant, wherein the content of the glass fibers relative to the total of the thermoplastic resin composition and the glass fibers is 25.0 to 55.0 mass%. [2] The fiber-reinforced thermoplastic resin composition according to [1], further comprising 0.5 to 10.0 parts by mass of a flame retardant aid relative to 100 parts by mass of the styrene-based resin composition. [3] The fiber-reinforced thermoplastic resin composition according to [1] or [2], wherein the thermoplastic resin composition further comprises 0.3 to 3.0 parts by mass of hydrotalcite relative to 100 parts by mass of the styrene-based resin composition. [4] The fiber-reinforced thermoplastic resin composition according to any one of [1] to [3], wherein the thermoplastic resin composition further comprises 3.0 to 20.0 parts by mass of magnesium hydroxide relative to 100 parts by mass of the styrene-based resin composition. [5] The fiber-reinforced thermoplastic resin composition according to any one of [1] to [4], wherein the glass fiber having a flat cross section has an irregularity ratio of 2.0 to 6.0. [6] A resin-metal composite comprising a resin member made of the fiber-reinforced thermoplastic resin composition according to any one of [1] to [5], and a metal member. [7] The resin-metal composite according to [6], wherein the metal member is at least one selected from the group consisting of aluminum, stainless steel, copper, titanium, and alloys thereof.

[0009] According to the present invention, it is possible to provide a fiber-reinforced thermoplastic resin composition that has excellent flame retardancy and, when used as a resin member of a metal-resin composite, also has excellent heat shock resistance, and a metal-resin composite using the same.

[0010] It is a schematic diagram showing a cut-out portion of a test piece for measuring the MD linear expansion coefficient (MD-CTE) and TD linear expansion coefficient (TD-CTE) of a fiber reinforced resin composition. It is a schematic diagram of a test piece for evaluating the heat shock resistance of a resin metal composite of the present invention. It is a schematic cross-sectional view of a test piece for evaluating the heat shock resistance of a resin metal composite of the present invention. It is a schematic diagram of a mold for a test piece for evaluating the heat shock resistance of a resin metal composite of the present invention.

[0011] [Fiber-reinforced thermoplastic resin composition] The fiber-reinforced thermoplastic resin composition of the present invention is a fiber-reinforced thermoplastic resin composition comprising a thermoplastic resin composition and glass fibers having a flat cross section, wherein the thermoplastic resin composition comprises 75.0 to 94.0 parts by mass of a styrene-based polymer having a syndiotactic structure having a weight average molecular weight of less than 230,000 and 6.0 to 25.0 parts by mass of a rubber-like elastomer. 100 parts by mass of a styrene-based resin composition, and 11.0 to 30.0 parts by mass of a bromine-based flame retardant, and the content of the glass fiber relative to the total of the thermoplastic resin composition and the glass fiber is 25.0 to 55.0% by mass.

[0012] Typically, the linear expansion coefficient of resins is significantly different from that of metals. Therefore, common methods for improving the heat shock resistance of resins include adding a filler component such as glass fiber to the resin to reduce the linear expansion coefficient of the resin composition and bring it closer to that of metal, and adding a material capable of buffering strain due to temperature changes, such as an elastomer, to the resin to relieve the strain that occurs between the resin and metal in a resin-metal composite. On the other hand, the fiber-reinforced thermoplastic resin composition of the present invention uses glass fibers having a flat cross-section as a filler for the styrene-based resin composition, which reduces the TD linear expansion coefficient and brings it closer to that of metal compared to when glass fibers without a flat cross-section are used, thereby improving heat shock resistance. Furthermore, the fiber-reinforced thermoplastic resin composition of the present invention can be imparted with flame retardancy and further improve its heat shock resistance by using a brominated flame retardant. The reason why the brominated flame retardant improves heat shock resistance is unclear, but the following is considered. It is believed that the brominated flame retardant has a higher melting point and a smaller linear expansion coefficient than the styrene-based polymer having a syndiotactic structure used in the present invention. Furthermore, the brominated flame retardant is characterized by being smaller in size than glass fibers having a flat cross section. Therefore, when molded into a resin-metal composite, the brominated flame retardant can be present together with the styrene-based polymer, even in the fine details or outermost layer where glass fibers are unlikely to be present. Therefore, in a resin-metal composite using the fiber-reinforced thermoplastic resin composition of the present invention, in the region of the resin member where glass fibers are sufficiently present, in addition to the effect of reducing the linear expansion coefficient of the glass fibers, the effect of reducing the linear expansion coefficient due to the brominated flame retardant can be obtained. Furthermore, even in the region of the resin member where glass fibers are not sufficiently present, the presence of the brominated flame retardant makes it possible to reduce the linear expansion coefficient. From the above, it is believed that the fiber-reinforced thermoplastic resin composition of the present invention has excellent flame retardancy and also excellent heat shock resistance when used as a resin member of a metal-resin composite.

[0013] <Thermoplastic resin composition> In the fiber-reinforced thermoplastic resin composition of the present invention, the thermoplastic resin composition contains 100 parts by mass of a styrene-based resin composition consisting of 75.0 to 94.0 parts by mass of a styrene-based polymer having a syndiotactic structure and a weight-average molecular weight of less than 230,000 and 6.0 to 25.0 parts by mass of a rubber-like elastomer, and 11.0 to 30.0 parts by mass of a bromine-based flame retardant.

[0014] (Styrene-Based Resin Composition) The styrene-based resin composition comprises 75.0 to 94.0 parts by mass of a styrene-based polymer having a syndiotactic structure and a weight-average molecular weight of less than 230,000, and 6.0 to 25.0 parts by mass of a rubber-like elastomer.

[0015] [Styrenic polymer having syndiotactic structure] A styrene polymer having a syndiotactic structure (hereinafter also referred to as SPS) is a styrene resin having a high degree of syndiotactic structure. In this specification, "syndiotactic" means that the phenyl rings of adjacent styrene units are arranged alternately with respect to the plane formed by the main chain of the polymer block (hereinafter referred to as syndiotacticity). Tacticity can be determined by nuclear magnetic resonance spectroscopy using carbon isotopes ( 13 Quantitative identification can be performed using 1C-NMR. 13 By C-NMR, the proportion of a plurality of consecutive structural units, for example, two consecutive monomer units as a diad, three consecutive monomer units as a triad, and five consecutive monomer units as a pentad, can be quantified.

[0016] In the present invention, "styrene-based resins having a highly syndiotactic structure" refers to styrene-based polymers such as polystyrene, poly(hydrocarbon-substituted styrene), poly(halogenated styrene), poly(halogenated alkylstyrene), poly(alkoxystyrene), and poly(vinyl benzoate ester), hydrogenated polymers or mixtures thereof, or copolymers containing these as the main component, having a syndiotacticity of typically 75 mol% or more, preferably 85 mol% or more, in racemic diad (r), or typically 30 mol% or more, preferably 50 mol% or more, in racemic pentad (rrrr). In this specification, the term "main component" refers to a component whose content exceeds 50 mol%. The content of the main component is preferably 60 to 100 mol%, more preferably 70 to 100 mol%, even more preferably 80 to 100 mol%, even more preferably 90 to 100 mol%, and even more preferably 95 to 100 mol%.

[0017] Examples of poly(hydrocarbon-substituted styrenes) include poly(methylstyrene), poly(ethylstyrene), poly(isopropylstyrene), poly(tert-butylstyrene), poly(phenylstyrene), poly(vinylnaphthalene), and poly(vinylstyrene). Examples of poly(halogenated styrenes) include poly(chlorostyrene), poly(bromostyrene), and poly(fluorostyrene), and examples of poly(halogenated alkylstyrenes) include poly(chloromethylstyrene). Examples of poly(alkoxystyrenes) include poly(methoxystyrene) and poly(ethoxystyrene).

[0018] Examples of comonomer components of copolymers containing the above-mentioned structural units include, in addition to the monomers of the styrene polymers, olefin monomers such as ethylene, propylene, butene, hexene, and octene; diene monomers such as butadiene and isoprene; and polar vinyl monomers such as cyclic olefin monomers, cyclic diene monomers, methyl methacrylate, maleic anhydride, and acrylonitrile. Copolymers that are preferably used as SPS include copolymers of styrene and p-methylstyrene, copolymers of styrene and p-tert-butylstyrene, and copolymers of styrene and divinylbenzene, with a copolymer of styrene and p-methylstyrene being preferred.

[0019] Among the SPSs, one or more selected from polystyrene, poly(p-methylstyrene), poly(m-methylstyrene), poly(p-tert-butylstyrene), poly(p-chlorostyrene), poly(m-chlorostyrene), poly(p-fluorostyrene), and a copolymer of styrene and p-methylstyrene are preferred, one or more selected from polystyrene, poly(p-methylstyrene), poly(m-methylstyrene), and a copolymer of styrene and p-methylstyrene are more preferred, polystyrene and a copolymer of styrene and p-methylstyrene are even more preferred, and polystyrene is most preferred.

[0020] The melt flow rate (MFR) of SPS is preferably 8 g / 10 min or more and 50 g / 10 min or less, more preferably 10 g / 10 min or more and 40 g / 10 min or less, and even more preferably 13 g / 10 min or more and 35 g / 10 min or less, when measured under conditions of a temperature of 300 ° C. and a load of 1.2 kg. If the MFR of SPS is 8 g / 10 min or more, there is no problem with the fluidity of the fiber-reinforced resin composition during molding, and if it is 50 g / 10 min or less, a resin-metal composite having sufficient strength can be obtained.

[0021] In the present invention, the weight average molecular weight of SPS is less than 230,000. By having a weight average molecular weight of SPS less than 230,000, the fluidity of the fiber-reinforced thermoplastic resin composition during molding can be ensured, and the strength of the resulting resin-metal composite can be sufficient. The weight average molecular weight of SPS is preferably 10,000 or more and less than 200,000, more preferably 50,000 or more and less than 190,000, and even more preferably 100,000 or more and less than 185,000. By having a weight average molecular weight of SPS of 10,000 or more, the strength of the resulting resin-metal composite can be ensured and the heat shock resistance can be increased. Furthermore, by having a weight average molecular weight of SPS less than 230,000, the fluidity of the fiber-reinforced thermoplastic resin composition during molding can be ensured. In this specification, unless otherwise specified, the weight-average molecular weight is a value measured by gel permeation chromatography at 145°C using a GPC apparatus (HLC-8321GPC / HT) manufactured by Tosoh Corporation and a GPC column (GMHHR-H(S)HTC / HT) manufactured by Tosoh Corporation, using 1,2,4-trichlorobenzene as an eluent, and converted using a calibration curve of standard polystyrene. Methods for adjusting the weight-average molecular weight of SPS include appropriately selecting the type, amount used, and polymerization temperature of each catalyst component, and introducing hydrogen.

[0022] The content of SPS per 100 parts by mass of the styrene-based resin composition is 75.0 to 94.0 parts by mass, preferably 77.0 to 93.0 parts by mass, more preferably 78.0 to 92.0 parts by mass, and even more preferably 79.0 to 91.0 parts by mass. By having the SPS content within the above range, it is possible to improve the heat shock resistance when used as a resin member of a metal-resin composite.

[0023] SPS can be produced, for example, by polymerizing a styrene-based monomer (a monomer corresponding to the above-mentioned styrene-based polymer) in an inert hydrocarbon solvent or in the absence of a solvent, using a titanium compound and a condensation product (aluminoxane) of water with trialkylaluminum as catalysts (for example, JP 2009-068022 A).

[0024] [Rubber-like elastomer] In the fiber-reinforced thermoplastic resin composition of the present invention, by containing a rubber-like elastomer, the thermoplastic resin composition can improve toughness while maintaining dimensional stability, and can increase heat shock resistance when used as a resin component of a metal-resin composite.

[0025] The rubber-like elastic material is not limited as long as it is an elastomer containing structural units derived from styrene, but is preferably at least one selected from the group consisting of styrene-diene block copolymers, hydrogenated styrene-diene block copolymers, styrene-diene random copolymers, hydrogenated styrene-diene random copolymers, and styrene-olefin random copolymers. Here, dienes copolymerized with styrene include butadiene and isoprene, and olefins copolymerized with styrene include ethylene, propylene, and butylene.

[0026] The rubber-like elastomer is more preferably at least one selected from the group consisting of styrene-butadiene block copolymer (SBR), hydrogenated styrene-butadiene block copolymer (SEB), styrene-butadiene-styrene block copolymer (SBS), hydrogenated styrene-butadiene-styrene block copolymer (SEBS), styrene-isoprene block copolymer (SIR), hydrogenated styrene-isoprene block copolymer (SEP), styrene-isoprene-styrene block copolymer (SIS), hydrogenated styrene-isoprene-styrene block copolymer (SEPS), styrene-butadiene random copolymer, hydrogenated styrene-butadiene random copolymer, styrene-ethylene-propylene random copolymer, and styrene-ethylene-butylene random copolymer, and is further preferably styrene-butadiene block copolymer (SBR), hydrogenated styrene-butadiene block copolymer (SEB), styrene-butadiene-styrene block copolymer (SBS), hydrogenated styrene-butadiene-styrene block copolymer (SEB S), styrene-isoprene block copolymer (SIR), hydrogenated styrene-isoprene block copolymer (SEP), styrene-isoprene-styrene block copolymer (SIS), and hydrogenated styrene-isoprene-styrene block copolymer (SEPS), and even more preferably at least one selected from the group consisting of styrene-butadiene-styrene block copolymer (SBS), hydrogenated styrene-butadiene-styrene block copolymer (SEBS), styrene-isoprene-styrene block copolymer (SIS), and hydrogenated styrene-isoprene-styrene block copolymer (SEPS), and even more preferably at least one selected from the group consisting of hydrogenated styrene-butadiene-styrene block copolymer (SEBS), and styrene-isoprene-styrene block copolymer (SIS), and hydrogenated styrene-isoprene-styrene block copolymer (SEPS), and even more preferably hydrogenated styrene-butadiene-styrene block copolymer (SEBS).

[0027] The mass ratio of the styrene-derived structural units to the total of the diene-, hydrogenated diene-, and olefin-derived structural units constituting the rubbery elastomer [(styrene) / (diene, hydrogenated diene, olefin)] is preferably 20 / 80 to 70 / 30, more preferably 25 / 75 to 60 / 40, and even more preferably 25 / 75 to 45 / 55. The styrene content of the rubbery elastomer is preferably in the range of 25.0 to 60.0 mass%, and more preferably 25.0 to 45.0 mass%. By achieving such a mass ratio, compatibility with SPS can be improved, and toughness can be improved while maintaining heat resistance and dimensional stability at high temperatures.

[0028] The content of the rubber-like elastomer in 100 parts by mass of the styrene-based resin composition is 6.0 to 25.0 parts by mass, preferably 7.0 to 20.0 parts by mass, more preferably 8.0 to 15.0 parts by mass, and even more preferably 8.0 to 12.0 parts by mass. By having the content of the rubber-like elastomer within the above range, it is possible to improve the heat shock resistance when used as a resin member of a metal-resin composite.

[0029] (Brominated flame retardant) In the fiber-reinforced thermoplastic resin composition of the present invention, the thermoplastic resin composition contains a brominated flame retardant, which can impart flame retardancy and further enhance the heat shock resistance when used as a resin component of a metal-resin composite.

[0030] The brominated flame retardant can be arbitrarily selected from known compounds and is preferably at least one selected from brominated polystyrene, ethylene-1,2-bis(pentabromophenyl), ethylene bis(tetrabromophthalimide), pentabromobenzyl polyacrylate, and tetrabromobisphenol A, more preferably ethylene-1,2-bis(pentabromophenyl).

[0031] The content of the brominated flame retardant in the thermoplastic resin composition is 11.0 to 30.0 parts by mass, preferably 12.0 to 25.0 parts by mass, more preferably 13.0 to 20.0 parts by mass, and even more preferably 14.0 to 18.0 parts by mass, per 100 parts by mass of the styrene-based resin composition. By having the content of the brominated flame retardant within the above range, sufficient flame retardancy is exhibited without reducing productivity. Furthermore, heat shock resistance is further improved. Furthermore, by having the content of the brominated flame retardant in the thermoplastic resin composition be equal to or less than the above upper limit, tracking resistance can be improved, and by having the content be equal to or less than 20.0 parts by mass, tracking resistance can be further improved.

[0032] (Other Flame Retardants) In the fiber-reinforced thermoplastic resin composition of the present invention, the thermoplastic resin composition may contain other flame retardants in addition to the above-mentioned bromine-based flame retardants. The other flame retardants may be arbitrarily selected from known flame retardants such as condensed phosphate esters, ammonium polyphosphates, phosphinates, phosphites, melamine cyanurate, magnesium hydroxide, and boehmite.

[0033] [Magnesium Hydroxide] The fiber-reinforced thermoplastic resin composition of the present invention preferably contains magnesium hydroxide as an additional flame retardant. By including magnesium hydroxide as an additional flame retardant, flame retardancy can be further enhanced. Furthermore, magnesium hydroxide has a smaller linear expansion coefficient than the syndiotactic polystyrene used in the present invention and is smaller in size than glass fibers having a flat cross section. Therefore, when used as a resin component of a metal-resin composite, magnesium hydroxide particles penetrate into details where glass fibers cannot be present in sufficient detail, thereby further enhancing heat shock resistance. Furthermore, the inclusion of magnesium hydroxide can further enhance tracking resistance. The content of magnesium hydroxide in the thermoplastic resin composition is preferably 3.0 to 20.0 parts by mass, more preferably 5.0 to 18.0 parts by mass, and even more preferably 8.0 to 15.0 parts by mass, per 100 parts by mass of the styrene-based resin composition. By including magnesium hydroxide within the above range, flame retardancy, heat shock resistance, and tracking resistance can be further enhanced.

[0034] (Flame Retardant Auxiliary Agent) In the fiber-reinforced thermoplastic resin composition of the present invention, the thermoplastic resin composition preferably further contains a flame retardant auxiliary agent. The flame retardant auxiliary agent has a smaller linear expansion coefficient than the syndiotactic polystyrene used in the present invention and a smaller size than glass fibers having a flat cross section. Therefore, when molded into a resin-metal composite, the flame retardant auxiliary agent can be present together with the styrene-based polymer even in the fine details or outermost layer where glass fibers are unlikely to be present. As a result, by further containing a flame retardant auxiliary agent in the thermoplastic resin composition, flame retardancy and heat shock resistance can be further improved. The flame retardant auxiliary agent can be arbitrarily selected from known agents and used. Preferably, one or more selected from diantimony trioxide, sodium antimonate, diantimony pentoxide, and zinc borate are selected. More preferably, one or more selected from diantimony trioxide and zinc borate are selected. Diantimony trioxide is even more preferred.

[0035] In the fiber-reinforced thermoplastic resin composition of the present invention, the content of the flame retardant aid in the thermoplastic resin composition is preferably 0.5 to 15.0 parts by mass, more preferably 1.0 to 13.0 parts by mass, and even more preferably 3.0 to 10.0 parts by mass, relative to 100 parts by mass of the styrene-based resin composition. By having the content of the flame retardant aid within the above range, flame retardancy can be further improved. Furthermore, in the fiber-reinforced thermoplastic resin composition of the present invention, the mass ratio of the content of the flame retardant aid to the content of the brominated flame retardant (flame retardant aid / brominated flame retardant) is preferably 0.10 to 1.00, more preferably 0.15 to 0.50, and even more preferably 0.20 to 0.40. By having the mass ratio (flame retardant aid / brominated flame retardant) within the above range, flame retardancy can be further improved.

[0036] (Stabilizer) In the fiber-reinforced thermoplastic resin composition of the present invention, the thermoplastic resin composition preferably further contains a stabilizer. By adding a stabilizer to the thermoplastic resin composition, decomposition of the resin during kneading can be suppressed. In the fiber-reinforced thermoplastic resin composition of the present invention, the thermoplastic resin composition preferably further contains hydrotalcite as a stabilizer. By containing hydrotalcite as a stabilizer, it is possible to capture halogens generated by heat generation during resin kneading and suppress decomposition of the resin, thereby further improving productivity. In the fiber-reinforced thermoplastic resin composition of the present invention, the content of hydrotalcite in the thermoplastic resin composition is preferably 0.3 to 3.0 parts by mass, more preferably 0.5 to 2.0 parts by mass, and even more preferably 0.8 to 1.5 parts by mass, relative to 100 parts by mass of the styrene-based resin composition. By having the hydrotalcite content within the above range, productivity can be further improved.

[0037] (Nucleating Agent) In the fiber-reinforced thermoplastic resin composition of the present invention, the thermoplastic resin composition preferably further contains a nucleating agent. By containing a nucleating agent in the thermoplastic resin composition, the crystallization temperature can be increased, allowing a wide range of temperature conditions for crystallization to be set, and productivity can be improved.

[0038] The crystal nucleating agent is preferably at least one selected from the group consisting of inorganic crystal nucleating agents and organic crystal nucleating agents. Of these, organic crystal nucleating agents are preferred. Examples of organic crystal nucleating agents include alkali metal salts of organic carboxylic acids, alkaline earth metal salts of organic carboxylic acids, organic compounds of phosphoric acid or phosphorous acid and their metal salts, phthalocyanine derivatives, and sorbitol derivatives. More specific examples include metal salts of carboxylic acids such as aluminum di(p-tert-butylbenzoate), sodium salt of benzoic acid, hydroxyaluminum salt of p-tert-butylbenzoic acid, and aluminum hydroxy-di(p-tert-butylbenzoate), sodium methylenebis(2,4-di-tert-butylphenyl)phosphate, sodium-2,2'-methylenebis(4,6-di-tert-butylphenyl)phosphate, and [2,2'-methylenebis(4,6-di-tert-butylphenyl)]phosphate. Metal salts of phosphoric acid such as lithium, [2,2'-methylenebis(4,6-di-tert-butylphenyl)]]phosphate, potassium bis(4-tert-butylphenyl)phosphate, sodium methylene(2,4-tert-butylphenyl)phosphate, aluminum bis(4,6',6,6'-tetra-tert-butyl-2,2'-methylenediphenyl phosphate) hydroxide, and ammonium [2,2'-methylenebis(4,6-di-tert-butylphenyl)]]phosphate can be selected and used. Complexes containing these can also be used. Among these, from the viewpoint of increasing the crystallization temperature, it is preferable to use a lithium salt of an organic compound of phosphoric acid or phosphorous acid, and it is more preferable to use lithium [2,2'-methylenebis(4,6-di-tert-butylphenyl)]]phosphate.

[0039] In the fiber-reinforced thermoplastic resin composition of the present invention, the content of the crystal nucleating agent in the thermoplastic resin composition is preferably 0.6 to 2.0 parts by mass, more preferably 0.7 to 1.8 parts by mass, and even more preferably 0.8 to 1.5 parts by mass, relative to 100 parts by mass of the styrene-based resin composition. By having the content of the crystal nucleating agent be 0.6 parts by mass or more, it is possible to set a wide range of temperature conditions for crystallization, thereby improving productivity. Furthermore, by having the content be 2.0 parts by mass or less, the amount of gas components generated when used as a resin component of a metal-resin composite can be reduced, resulting in a good appearance.

[0040] (Modified polyphenylene ether) In the fiber-reinforced thermoplastic resin composition of the present invention, the thermoplastic resin composition preferably further contains a modified polyphenylene ether. By containing the modified polyphenylene ether in the thermoplastic resin composition, the interfacial strength between the thermoplastic resin composition and the glass fiber described below can be increased, so that when used as a resin member of a metal-resin composite, the strength of the resin member as a structure is increased. As a result, the heat shock resistance can be improved.

[0041] Further, in the fiber-reinforced thermoplastic resin composition of the present invention, the content of the modified polyphenylene ether in the thermoplastic resin composition is preferably 0.1 to 15.0 parts by mass, more preferably 0.5 to 10.0 parts by mass, even more preferably 1.0 to 6.0 parts by mass, and even more preferably 1.5 to 4.0 parts by mass, relative to 100 parts by mass of the styrene-based resin composition. By having a content of modified polyphenylene ether of 0.1 parts by mass or more, the interfacial strength between the thermoplastic resin composition and the glass fiber described below can be increased, so that when used as a resin member of a metal-resin composite, the strength of the resin member as a structure is increased and heat shock resistance can be improved. Furthermore, by having a content of 15.0 parts by mass or less, sufficient crystallinity can be ensured, making it easier to ensure heat resistance and rigidity.

[0042] The modified polyphenylene ether is compatible with SPS and improves compatibility with other components, and preferably has a polar group reactive with glass fiber, as described below. The modified polyphenylene ether is blended to improve compatibility between SPS and other components and glass fiber, thereby improving the interfacial strength between the components. More specifically, the modified polyphenylene ether is preferably an acid-modified polyphenylene ether. The polar group reactive with glass fiber refers to a functional group capable of reacting with the polar group contained in the glass fiber. Specific examples include an acid anhydride group, a carboxylic acid group, a carboxylic acid ester group, a carboxylic acid halide group, a carboxylic acid amide group, a carboxylic acid salt group, a sulfonic acid group, a sulfonic acid ester group, a sulfonic acid chloride group, a sulfonic acid amide group, a sulfonic acid salt group, an epoxy group, an amino group, an imide group, and an oxazoline group, with a carboxylic acid group being preferred.

[0043] As the modified polyphenylene ether, fumaric acid-modified polyphenylene ether and maleic anhydride-modified polyphenylene ether are preferred, and fumaric acid-modified polyphenylene ether is more preferred.

[0044] The modification amount (modifier content) of the modified polyphenylene ether is preferably 0.1 to 20.0 mass%, more preferably 0.2 to 15.0 mass%, even more preferably 0.3 to 10.0 mass%, and even more preferably 0.5 to 5.0 mass%. When the modification amount is within this range, a styrene-based resin composition and a molded article having good strength and heat resistance can be obtained. The modification amount (modifier content) of the modified polyphenylene ether can be determined by the neutralization titer measured in accordance with JIS K 0070-1992.

[0045] Examples of polyphenylene ethers include poly(2,6-dimethyl-1,4-phenylene ether), poly(2,3-dimethyl-6-ethyl-1,4-phenylene ether), poly(2-methyl-6-chloromethyl-1,4-phenylene ether), poly(2-methyl-6-hydroxyethyl-1,4-phenylene ether), poly(2-methyl-6-n-butyl-1,4-phenylene ether), poly(2-ethyl-6-isopropyl-1,4-phenylene ether), poly(2-ethyl-6-n-propyl-1,4-phenylene ether), poly(2,3,6-trimethyl-1,4-phenylene ether), poly[2-(4'-methylphenyl)-1,4-phenylene ether], poly(2-bromo-6-phenyl-1,4-phenylene ether), poly(2-methyl-6-phenyl-1,4-phenylene ether), poly( 2-phenyl-1,4-phenylene ether), poly(2-chloro-1,4-phenylene ether), poly(2-methyl-1,4-phenylene ether), poly(2-chloro-6-ethyl-1,4-phenylene ether), poly(2-chloro-6-bromo-1,4-phenylene ether), poly(2,6-di-n-propyl-1,4-phenylene ether), poly(2-methyl-6-isopropyl-1,4-phenylene ether), poly(2-chloro-6-methyl-1,4-phenylene ether), poly(2-methyl-6-ethyl-1,4-phenylene ether), poly(2,6-dibromo-1,4-phenylene ether), poly(2,6-dichloro-1,4-phenylene ether), poly(2,6-diethyl-1,4-phenylene ether), and the like are mentioned, and poly(2,6-dimethyl-1,4-phenylene ether) is preferred.

[0046] Modifiers used to modify polyphenylene ether include compounds having an ethylenic double bond and a polar group in the same molecule, specifically, for example, maleic anhydride, maleic acid, fumaric acid, maleic acid esters, fumaric acid esters, maleimide and its N-substituted derivatives, maleates, fumarates, acrylic acid, acrylic acid esters, acrylic acid amides, acrylic acid salts, methacrylic acid, methacrylic acid esters, methacrylic acid amides, methacrylic acid salts, and glycidyl methacrylate. Among these, maleic anhydride, fumaric acid, and glycidyl methacrylate are particularly preferred, and fumaric acid is more preferred. The above-mentioned various modifiers may be used alone or in combination of two or more.

[0047] The modified polyphenylene ether is obtained by reacting the polyphenylene ether with a modifier. There are no particular limitations on the modification method, and known methods can be used. Preferred modification methods include melt modification and solution modification, and among these, melt modification is more preferred because a higher degree of modification can be obtained and productivity is high. That is, the modified polyphenylene ether is preferably a modified polyphenylene ether produced by melt modification or a modified polyphenylene ether produced by solution modification, and more preferably a modified polyphenylene ether produced by melt modification.

[0048] Melt modification is a method of obtaining a modified polyphenylene ether by melt-kneading polyphenylene ether and a modifier in the presence or absence of a radical generator. Specifically, this is a method of melt-kneading and reacting at a temperature in the range of 150 to 350°C using a roll mill, Banbury mixer, extruder, or the like. Specifically, a method is preferred in which polyphenylene ether, a modifier, and an optional radical generator are uniformly dry-blended at room temperature, and then the melt reaction is carried out at a temperature in the range of 300 to 350°C, which is essentially the kneading temperature of polyphenylene ether. If the temperature is 300°C or higher, the melt viscosity can be appropriately maintained, and if the temperature is 350°C or lower, decomposition of the polyphenylene ether can be suppressed.

[0049] The amount of the modifier used in the melt modification is preferably 0.1 to 22.0 parts by mass, more preferably 0.2 to 17.0 parts by mass, even more preferably 0.3 to 12.0 parts by mass, and still more preferably 0.5 to 7.0 parts by mass, relative to 100 parts by mass of polyphenylene ether. When the amount of the modifier used is within this range, a styrene-based resin composition and a molded article having good strength and heat resistance can be obtained.

[0050] The radical generator used for melt modification is preferably one having a temperature showing a half-life of 1 minute of 300°C or higher. Specific examples include 2,3-dimethyl-2,3-diphenylbutane, 2,3-diethyl-2,3-diphenylbutane, 2,3-diethyl-2,3-diphenylhexane, and 2,3-dimethyl-2,3-di(p-methylphenyl)butane. Of these, 2,3-dimethyl-2,3-diphenylbutane, which has a temperature showing a half-life of 1 minute of 330°C, is preferably used. The proportion of the radical generator used is preferably selected from the range of 0.1 to 3.0 parts by mass, more preferably 0.5 to 2.0 parts by mass, per 100 parts by mass of polyphenylene ether. If the amount is 0.1 part by mass or more, a high modification effect can be obtained, and if the amount is 3.0 parts by mass or less, the polyphenylene ether can be efficiently modified and insoluble components are less likely to be produced.

[0051] (Antioxidant) In the fiber-reinforced thermoplastic resin composition of the present invention, the thermoplastic resin composition preferably further contains an antioxidant from the viewpoint of heat resistance. The antioxidant is preferably one or more selected from phenolic compounds, phosphorus compounds, and sulfur compounds, and from the viewpoint of heat resistance, a phenolic compound is more preferred.

[0052] Specific examples of phenolic antioxidants include 2,6-di-tert-butyl-4-methylphenol, 2,6-diphenyl-4-methoxyphenol, 2,2'-methylenebis(6-tert-butyl-4-methylphenol), 2,2'-methylenebis[4-methyl-6-(α-methylcyclohexyl)phenol], 1,1-bis(5-tert-butyl-4-hydroxy-2-methylphenyl)butane, 2,2'-methylenebis(4-methyl-6-cyclohexylphenol), 2,2'-methylenebis(4-methyl-6-nonylphenol), 1,1,3-tris(5-tert-butyl-4-hydroxy-2-methylphenyl)butane, and 2,2-bis(5-tert-butyl-4-hydroxy-2-methylphenyl)-4-n-dodecylmercaptobutane. ethylene glycol bis[3,3-bis(3-tert-butyl-4-hydroxyphenyl)butyrate], 1,1-bis(3,5-dimethyl-2-hydroxyphenyl)-3-(n-dodecylthio)-butane, 4,4'-thiobis(6-tert-butyl-3-methylphenol), 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)-2,4,6-trimethylbenzene, 2,2-bis(3,5-di-tert-butyl-4-hydroxybenzyl)malonic acid dioctadecyl ester, n-octadecyl-3-(4-hydroxy-3,5-di-tert-butylphenyl)propionate, pentaerythritol tetrakis{3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate}, and the like. In particular, pentaerythritol tetrakis{3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate} is preferred.

[0053] Examples of the phosphorus-based antioxidant include monophosphites and diphosphites such as 3,9-bis(2,6-di-tert-butyl-4-methylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane, tris(2,4-di-tert-butylphenyl)phosphite, and tris(mono- and di-nonylphenyl)phosphite.

[0054] Examples of sulfur-based antioxidants include 2,2-bis{[3-(dodecylthio)-1-oxopropoxy]methyl}propane-1,3-diylbis[3-(dodecylthio)propionate], di(tridecyl) 3,3'-thiodipropionate, and 3,3'-thiodipropionate.

[0055] In the fiber-reinforced thermoplastic resin composition of the present invention, the content of the antioxidant per 100 parts by mass of the styrene-based resin composition in the thermoplastic resin composition is preferably 0.05 to 2.0 parts by mass, more preferably 0.1 to 1.8 parts by mass, even more preferably 0.3 to 1.5 parts by mass, and even more preferably 0.5 to 1.2 parts by mass. If the amount of the antioxidant is within the above range, the heat discoloration resistance during processing is good, long-term heat resistance can be obtained, and bleeding of the antioxidant can be suppressed, without adversely affecting the appearance.

[0056] (Release Agent) In the fiber-reinforced thermoplastic resin composition of the present invention, the thermoplastic resin composition preferably further contains a release agent. The release agent can be arbitrarily selected from known ones and is preferably one or more selected from polyethylene wax, silicone oil, and long-chain carboxylic acid, and silicone oil is more preferred. In the fiber-reinforced thermoplastic resin composition of the present invention, the content of the release agent relative to 100 parts by mass of the styrene-based resin composition in the thermoplastic resin composition is preferably 0.05 to 3.0 parts by mass, more preferably 0.1 to 2.0 parts by mass, even more preferably 0.2 to 1.5 parts by mass, even more preferably 0.3 to 1.2 parts by mass, and even more preferably 0.3 to 1.0 parts by mass.

[0057] <Glass fiber having a flat cross section> The fiber-reinforced thermoplastic resin composition of the present invention contains a glass fiber having a flat cross section. By containing a glass fiber having a flat cross section, the TD linear expansion coefficient can be reduced compared to when a glass fiber having a non-flat cross section is contained, and therefore the heat shock resistance when used as a resin member of a metal-resin composite can be improved.

[0058] In the present invention, glass fibers having a flat cross section have a flat cross section perpendicular to the fiber axis. The flat shape refers to a shape in which the irregularity ratio of a glass fiber having a flat cross section is greater than 1. In the present invention, the irregularity ratio is the ratio of the major axis to the minor axis, where the length of the long side of the rectangle having the smallest area circumscribing the cross section perpendicular to the longitudinal direction of the glass fiber is the major axis and the length of the short side of the rectangle is the minor axis. From the viewpoint of reducing the linear expansion coefficient and improving heat shock resistance when used as a resin member of a metal-resin composite, the irregularity ratio of a glass fiber having a flat cross section is preferably 2.0 to 6.0, more preferably 3.0 to 5.0, and even more preferably 3.5 to 4.5. The minor axis is preferably 3 to 10 μm, more preferably 5 to 8 μm. The major axis and minor axis of a glass fiber are both number averages, and are calculated as the number average by measuring 50 or more arbitrarily selected glass fibers through image analysis using a digital microscope.

[0059] The fiber diameter of the glass fiber having a flat cross section is preferably 10 to 20 μm, more preferably 11 to 19 μm, and even more preferably 12 to 18 μm. A fiber diameter of 10 μm or more reduces the linear expansion coefficient and improves heat shock resistance when used as a resin member of a metal-resin composite. Furthermore, a fiber diameter of 20 μm or less ensures the fluidity of the fiber-reinforced thermoplastic resin composition during molding. In the present invention, the fiber diameter of a glass fiber having a flat cross section refers to the diameter of a circle obtained by converting a cross section perpendicular to the fiber axis into a circle having the same area as the cross section. The fiber diameter of the glass fiber is a number average and is measured and calculated by performing image analysis using a digital microscope on 50 or more arbitrarily selected glass fibers.

[0060] The fiber length of the glass fiber having a flat cross section is preferably 1 to 50 mm, more preferably 1.5 to 15 mm, and even more preferably 2 to 8 mm, from the viewpoint of ensuring the fluidity of the fiber-reinforced thermoplastic resin composition during molding and handling. Furthermore, the fiber length of the glass fiber having a flat cross section is preferably 300 to 600 μm in the resin composition pellets due to breakage during extrusion kneading, etc. The fiber length of the glass fiber is a number average, and is measured and calculated by performing image analysis using a digital microscope on 50 or more arbitrarily selected glass fibers.

[0061] In order to enhance adhesion to SPS, glass fibers having a flat cross section are preferably surface-treated with a coupling agent, more preferably with a silane-based coupling agent or a titanium-based coupling agent, and even more preferably with a silane-based coupling agent from the viewpoint of compatibility with the resin component.

[0062] Specific examples of silane coupling agents include triethoxysilane, vinyltris(β-methoxyethoxy)silane, γ-methacryloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, β-(1,1-epoxycyclohexyl)ethyltrimethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, and γ-mercaptopropyltrimethoxysilane. Examples of suitable silanes include hydroxysilane, γ-chloropropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltris(2-methoxyethoxy)silane, N-methyl-γ-aminopropyltrimethoxysilane, N-vinylbenzyl-γ-aminopropyltriethoxysilane, 3-ureidopropyltrimethoxysilane, 3-4,5-dihydroimidazolepropyltriethoxysilane, hexamethyldisilazane, N,N-bis(trimethylsilyl)urea, and 3-triethoxysilyl-N-(1,3-dimethylbutylidene)propylamine. Among these, aminosilanes and epoxysilanes such as γ-aminopropyltrimethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane are preferred.

[0063] Specific examples of titanium-based coupling agents include isopropyl triisostearoyl titanate, isopropyl tridodecylbenzenesulfonyl titanate, isopropyl tris(dioctyl pyrophosphate) titanate, tetraisopropyl bis(dioctyl phosphite) titanate, tetraoctyl bis(ditridecyl phosphite) titanate, tetra(1,1-diallyloxymethyl-1-butyl)bis(ditridecyl)phosphite titanate, and bis(dioctyl pyrophosphate)oxyacetate. titanate, bis(dioctyl pyrophosphate)ethylene titanate, isopropyl trioctanoyl titanate, isopropyl dimethacryl isostearoyl titanate, isopropyl isostearoyl diacryl titanate, isopropyl tri(dioctyl phosphate)titanate, isopropyl tricumyl phenyl titanate, isopropyl tri(N-amidoethyl, aminoethyl)titanate, dicumyl phenyloxyacetate titanate, diisostearoyl ethylene titanate, etc. Among these, isopropyl tri(N-amidoethyl, aminoethyl)titanate is preferred.

[0064] In the present invention, the content of glass fibers having a flat cross section in the fiber-reinforced thermoplastic resin composition is 25.0 to 55.0 mass%, preferably 26.0 to 53.0 mass%, and more preferably 28.0 to 52.0 mass%, based on a total of 100 mass% of the thermoplastic resin composition and the glass fibers having a flat cross section. By having a content of glass fibers having a flat cross section of 25.0 mass% or more, the linear expansion coefficient can be reduced and the heat shock resistance when used as a resin member of a metal-resin composite can be improved. Furthermore, by having a content of glass fibers having a flat cross section of 55.0 mass% or less, the flowability of the fiber-reinforced thermoplastic resin composition during molding can be ensured while maintaining heat shock resistance and flame retardancy.

[0065] <Other Components> Any other components can be added to the fiber-reinforced thermoplastic resin composition of the present invention as long as the object of the present invention is not impaired. Examples of other components include colorants, crosslinking agents, crosslinking aids, dispersants, plasticizers, antifouling agents, UV absorbers, light stabilizers, and antistatic agents.

[0066] <Coloring Agent> Any coloring agent can be selected from known coloring agents such as carbon black, inorganic coloring agents, and organic coloring agents. Examples of inorganic coloring agents include inorganic pigments, and examples of organic coloring agents include organic pigments and organic dyes. Examples of inorganic pigments include titanium dioxide, iron oxide, nickel titanium yellow, zinc sulfide, barium sulfate, and ultramarine. Examples of organic pigments include at least one selected from the group consisting of monoazo pigments, perylene pigments, quinacridone pigments, and phthalocyanine pigments. Specific preferred examples of the organic pigment include monoazo pigments such as Pigment Yellow 183 and Pigment Yellow 150, perylene pigments such as Pigment Red 178 and Pigment Red 149, quinacridone pigments such as Pigment Violet 19, Pigment Red 122, Pigment Red 209, Pigment Red 202, Pigment Orange 48 and Pigment Orange 49, and phthalocyanine pigments such as Pigment Blue 15, Pigment Blue 16, Pigment Green 7 and Pigment Green 36.

[0067] <<Dispersant>> The dispersant can be arbitrarily selected from known dispersants such as methylene bisstearic acid amide, polyacrylic acid, sodium polyacrylate, sodium carboxylate, ammonium polyacrylate, polyacrylic acid copolymers, sodium polycarboxylate, carboxylic acid copolymers, and sulfonic acid copolymers.

[0068] <<Ultraviolet Absorbers>> Examples of ultraviolet absorbers include 2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol; 2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol; 2,2'-methylenebis[6-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol]; 2-(2H-benzotriazol-2-yl)-p-cresol; 2-(5-chloro-2H-benzotriazol-2-yl)-6-tert-butyl-4-methylphenol; 2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-[2-(2-ethylhexanoyloxy)ethoxy]phenol; Any known compound can be selected and used, such as 2,4,6-tris(2-hydroxy-4-hexyloxy-3-methylphenyl)-1,3,5-triazine; [2-hydroxy-4-(octyloxy)phenyl](phenyl)methanone; and the like.

[0069] <Light stabilizer> Examples of light stabilizers include tetrakis(1,2,2,6,6-pentamethyl-4-piperidyl)butane-1,2,3,4-tetracarboxylate; tetrakis(2,2,6,6-tetramethyl-4-piperidyl)butane-1,2,3,4-tetracarboxylate; reaction products of 1,2,3,4-butanetetracarboxylic acid tetramethyl ester with 1,2,2,6,6-pentamethyl-4-piperidinol and β,β,β',β'-tetramethyl-2,4,8,10-tetraoxaspiro[5.5]undecane-3,9-diethanol (ADK STAB LA-63P); Reaction products of 1,2,3,4-butanetetracarboxylic acid tetramethyl ester with 2,2,6,6-tetramethyl-4-piperidinol and β,β,β',β'-tetramethyl-2,4,8,10-tetraoxaspiro[5.5]undecane-3,9-diethanol (ADK STAB LA-68); Bis(1,2,2,6,6-pentamethyl-4-piperidyl)sebacate; Bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate; Bis(1-undecanoxy-2,2,6,6-tetramethylpiperidin-4-yl)carbonate; 1,2,2,6,6-pentamethyl-4-piperidyl methacrylate; 2,2,6,6-tetramethyl-4-piperidyl methacrylate; 2,2,6,6-tetramethylpiperidin-4-yl Any known compound can be selected and used, such as hexadecanoate; 2,2,6,6-tetramethylpiperidin-4-yl octadecanoate;

[0070] <Linear expansion coefficient of fiber-reinforced thermoplastic resin composition> The MD linear expansion coefficient (MD-CTE) of the fiber-reinforced thermoplastic resin composition depends on the combination with the metal member when used as a resin member of a metal-resin composite. However, from the viewpoint of reducing the difference between the linear expansion coefficient of the resin member made of the fiber-reinforced thermoplastic resin composition and the linear expansion coefficient of the metal member and improving heat shock resistance, the MD linear expansion coefficient (MD-CTE) of the fiber-reinforced thermoplastic resin composition is preferably 2.5 × 10 －５ / °C or less, and more preferably 2.0 × 10 －５The lower limit of the MD-CTE is not particularly limited, but is preferably 0.5×10 or less from the viewpoint of reducing the strain between the resin member and the metal member and suppressing the fracture of the resin-metal composite when used as a resin member of a metal-resin composite. －５ / °C or more. The MD linear expansion coefficient (MD-CTE) of the fiber-reinforced thermoplastic resin composition can be adjusted by the type and content of glass fibers having a flat cross section. In the present invention, the MD-CTE can be reduced by using glass fibers having a flat cross section. Furthermore, the MD-CTE tends to be reduced by increasing the content of glass fibers having a flat cross section.

[0071] The TD linear expansion coefficient (TD-CTE) of the fiber-reinforced thermoplastic resin composition depends on the combination with the metal member when used as a resin member of a metal-resin composite, but from the viewpoint of reducing the difference between the linear expansion coefficient of the resin member made of the fiber-reinforced thermoplastic resin composition and the linear expansion coefficient of the metal member and improving heat shock resistance, it is preferably 8.5 × 10 －５ / °C or less, and more preferably 8.0 × 10 －５ The lower limit of the TD-CTE is not particularly limited, but is preferably 2.0 × 10 or less from the viewpoint of reducing the strain between the resin member and the metal member and suppressing the fracture of the resin-metal composite when used as a resin member of a metal-resin composite. －５ / °C or more. The TD linear expansion coefficient (TD-CTE) of the fiber-reinforced thermoplastic resin composition can be adjusted by the type and content of glass fibers having a flat cross section. In the present invention, the TD-CTE can be reduced by using glass fibers having a flat cross section. Furthermore, the TD-CTE tends to be reduced by increasing the content of glass fibers having a flat cross section.

[0072] In the present invention, "MD" refers to the flow direction of the fiber-reinforced thermoplastic resin composition poured when molding a metal-resin composite, and "TD" refers to the direction perpendicular to the flow direction of the fiber-reinforced thermoplastic resin composition poured when molding a metal-resin composite. In the present invention, the linear expansion coefficient of the fiber-reinforced thermoplastic resin composition can be measured by the method described in the examples.

[0073] <Applications of Fiber-Reinforced Thermoplastic Resin Composition> The fiber-reinforced thermoplastic resin composition of the present invention has excellent flame retardancy and, when used as a resin component of a metal-resin composite, also has excellent heat shock resistance. Furthermore, the fiber-reinforced thermoplastic resin composition of one embodiment of the present invention also has excellent tracking resistance. Therefore, it can be used in harsh environments, such as in the electronics and electrical machinery fields, the automotive field, and the household appliances field, as a component integrating dissimilar materials such as metal and resin, where the component is alternately exposed to high and low temperatures. The operating temperature range can be, for example, a high temperature range of 110°C to 150°C, and a low temperature range of -50°C to -30°C. It can also be used in environments where the temperature difference is 140°C or more, or even 160°C or more. Specifically, the fiber-reinforced thermoplastic resin composition of the present invention can be used as terminal blocks and busbar members used in control circuit wiring for automotive lithium-ion batteries and electric vehicles, terminal blocks and busbar members used in panels such as distribution boards, switchboards, and control panels, terminal blocks and busbar members used in relay boxes for electric cables used in large machines, solenoid valves, etc. Therefore, according to the present invention, the following (1) to (4) are provided. (1) A method of using the fiber-reinforced thermoplastic resin composition of the present invention in an environment where the composition is alternately exposed to a high temperature environment of 110°C or higher and 150°C or lower and a low temperature environment of -50°C or higher and -30°C or lower. (2) Use of the fiber-reinforced thermoplastic resin composition of the present invention in an environment where the composition is alternately exposed to a high temperature environment of 110°C or higher and 150°C or lower and a low temperature environment of -50°C or higher and -30°C or lower. (3) A method of using the fiber-reinforced thermoplastic resin composition of the present invention in a terminal block, busbar member, or solenoid valve. (4) Use of the fiber-reinforced thermoplastic resin composition of the present invention as a terminal block, a bus bar member, or a solenoid valve.

[0074] <Production of fiber-reinforced thermoplastic resin composition> The fiber-reinforced thermoplastic resin composition of the present invention can be obtained by blending and kneading the above-mentioned styrene-based resin having a syndiotactic structure, rubber-like elastomer, bromine-based flame retardant, and glass fiber having a flat cross section, and, if necessary, the above-mentioned other flame retardants, flame retardant assistants, stabilizers, crystal nucleating agents, modified polyphenylene ethers, antioxidants, mold release agents, and other components. Blending and kneading can be performed by premixing using commonly used equipment such as a ribbon blender, drum tumbler, Henschel mixer, etc., followed by using a Banbury mixer, single-screw extruder, twin-screw extruder, multi-screw extruder, co-kneader, etc.

[0075] [Resin-metal composite] The resin-metal composite of the present invention includes a resin member made of the fiber-reinforced thermoplastic resin composition of the present invention described above, and a metal member. That is, the resin-metal composite of the present invention is a fiber-reinforced thermoplastic resin composition containing at least a thermoplastic resin composition and glass fibers having a flat cross section, wherein the thermoplastic resin composition contains 75.0 to 94.0 parts by mass of a styrene-based polymer having a syndiotactic structure and a weight average molecular weight of less than 230,000, and 6.0 to 25.0 parts by mass of a rubber-like elastomer. 100 parts by mass of a styrene-based resin composition, and 11.0 to 30.0 parts by mass of a bromine-based flame retardant, and the content of the glass fiber relative to the total of the thermoplastic resin composition and the glass fiber is 25.0 to 55.0% by mass. The fiber-reinforced thermoplastic resin composition is included as a resin member.

[0076] <Metal member> The metal member of the resin-metal composite of the present invention is preferably at least one selected from the group consisting of aluminum, stainless steel, copper, titanium, and alloys thereof, and more preferably at least one selected from aluminum, stainless steel, and copper. These metals can be selected according to the intended use and physical properties, and it is more preferable to use copper or a copper alloy. The shape of the metal member is not particularly limited and can be, for example, a flat plate, a curved plate, a rod, a cylinder, a block, etc. A structure consisting of a combination of these may also be used.

[0077] The coefficient of linear expansion (M-CTE) of the metal member is not particularly limited, but is preferably 0.5×10 －５ ~3.0 x 10 －５ / °C, and more preferably 1.0 × 10 －５ ~2.8 x 10 －５ / °C, and more preferably 1.5 × 10 －５ ~2.5 x 10 －５ / °C. M-CTE can be adjusted by the type of metal used in the metal member. The linear expansion coefficient of the metal member is measured in accordance with JIS Z2285:2003.

[0078] <Uses of Resin-Metal Composite> The resin-metal composite of the present invention contains the fiber-reinforced thermoplastic resin composition described above. Therefore, the resin-metal composite of the present invention has excellent flame retardancy and, further, due to the small difference between the linear expansion coefficient of the resin member and the linear expansion coefficient of the metal member, has excellent heat shock resistance. It also has excellent tracking resistance. Therefore, it can be used in harsh environments such as those where it is alternately exposed to high and low temperature environments, for example, as a part that integrates dissimilar materials, such as metal and resin, mainly in the electronics and electromechanical fields, automotive fields, and household appliances fields. The operating temperature range can be, for example, a high temperature range of 110°C to 150°C and a low temperature range of -50°C to -30°C, and it can also be used in environments where the temperature difference is 140°C or more, or even 160°C or more. Specifically, the resin-metal composite of the present invention can be used as terminal blocks and busbar members used in control circuit wiring for automotive lithium-ion batteries and electric vehicles, terminal blocks and busbar members used in panels such as distribution boards, switchboards, and control panels, terminal blocks and busbar members used in relay boxes for electric cables used in large machines, solenoid valves, etc. Therefore, according to the present invention, the following (5) to (8) are provided. (5) A method of using the resin-metal composite of the present invention in an environment where it is alternately exposed to a high-temperature environment of 110°C or higher and 150°C or lower and a low-temperature environment of -50°C or higher and -30°C or lower. (6) Use of the resin-metal composite of the present invention in an environment where it is alternately exposed to a high-temperature environment of 110°C or higher and 150°C or lower and a low-temperature environment of -50°C or higher and -30°C or lower. (7) A method of using the resin-metal composite of the present invention as a terminal block, busbar member, or solenoid valve. (8) Use of the resin-metal composite of the present invention as a terminal block, busbar member, or solenoid valve.

[0079] The present invention will be explained in more detail with reference to examples, but the present invention is not limited to these examples.

[0080] The raw materials used in the examples and comparative examples are as follows. <SPS (syndiotactic polystyrene)> - Syndiotactic polystyrene resin, weight average molecular weight: 150,000, MFR: 30 g / 10 min, manufactured by Idemitsu Kosan Co., Ltd. <Rubber-like elastomer> - "SEPTON 8006", hydrogenated styrene-butadiene-styrene block copolymer, styrene content 33%, manufactured by Kuraray Co., Ltd. <Flame retardant> - Brominated flame retardant: "SAYTEX 8010", ethylene-1,2-bis(pentabromophenyl), manufactured by Albemarle <Other flame retardants> - Magnesium hydroxide: "KISUMA 5P", magnesium hydroxide, manufactured by Kyowa Chemical Industry Co., Ltd. - Phosphorus-based flame retardant: "PX-200", aromatic condensed phosphate ester, manufactured by Daihachi Chemical Industry Co., Ltd. <Flame retardant synergist> - Diantimony trioxide: "PATOX-M", diantimony trioxide, manufactured by Nippon Seiko Co., Ltd. Zinc borate: "Firebrake ZB", zinc borate, manufactured by Borax Corporation <Stabilizer> Hydrotalcite: "DHT-4A", hydrotalcite, manufactured by Kyowa Chemical Industry Co., Ltd. <Nucleating agent> "ADK STAB NA-70", lithium [2,2'-methylenebis(4,6-di-tert-butylphenyl)]] phosphate, manufactured by ADEKA Corporation <Modified polyphenylene ether> "CX-1", fumaric acid modified polyphenylene ether, manufactured by Idemitsu Kosan Co., Ltd., modification amount 1.5 mass% <Antioxidant> "Irganox 1010", pentaerythritol tetrakis [3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], manufactured by BASF Corporation <Mold release agent> "KF-53", methylphenyl silicone oil, manufactured by Shin-Etsu Silicones Co., Ltd. <Glass fiber> Glass fiber having a flat cross section: "ECS 03 T-249-FGF", cross section: flat (minor axis: 7 μm, irregularity ratio: 4), fiber length: 3 mm, manufactured by Nippon Electric Glass Co., Ltd. Glass fiber not having a flat cross section: "ECS 03 T-249H", cross section: perfect circle, fiber diameter: 10.5 μm, fiber length: 3 mm, manufactured by Nippon Electric Glass Co., Ltd.

[0081] [Preparation of fiber-reinforced resin composition] Examples 1 to 8, Comparative Examples 1 to 9 Each component other than glass fiber was blended in the proportions shown in Tables 1 and 2 and dry-blended using a Henschel mixer. Subsequently, using a twin-screw extruder TEM37SS (manufactured by Shibaura Machine Co., Ltd.), the resin composition was kneaded at a screw rotation speed of 250 rpm and a barrel temperature of 290 ° C. while side-feeding the glass fiber in the proportions shown in Tables 1 and 2 to produce pellets. The obtained pellets were dried at 120 ° C. for 5 hours using a hot air dryer to obtain pellets of a fiber-reinforced thermoplastic resin composition. Evaluations were performed using the obtained pellets of the fiber-reinforced thermoplastic resin composition.

[0082] [Measurement and Evaluation Methods] (1) Measurement of Linear Expansion Coefficient (1-1) Linear Expansion Coefficient of Fiber-Reinforced Resin Composition (Resin Member) Using an injection molding machine SE100-EVA (manufactured by Sumitomo Heavy Industries, Ltd.), a cylinder temperature of 290 °C and a mold temperature of 150 °C, a 4 mm thick dumbbell-shaped test piece was prepared from pellets of the obtained reinforced thermoplastic resin composition. Here, the dumbbell-shaped test piece was a multipurpose test piece (Type A1) prepared in accordance with JIS K7139:2009. Test pieces were cut out from the obtained dumbbell-shaped test piece at the positions of the test piece cutout portion 11 for measuring the linear expansion coefficient in the MD (MD-CTE) and the test piece cutout portion 12 for measuring the linear expansion coefficient in the TD (TD-CTE) in Figure 1, respectively. The size of the test piece was 4 mm wide x 10 mm long x 4 mm thick. Also, at this time, the test pieces were cut out so that the length direction of the test piece for measuring the linear expansion coefficient in the MD (MD-CTE) or the width direction of the test piece for measuring the linear expansion coefficient in the TD (TD-CTE) coincided with the resin flow direction (MD) of the dumbbell-shaped test piece 1. Using the obtained test pieces, the linear expansion coefficient in each direction of the fiber reinforced resin composition (resin member) was measured using a thermomechanical analyzer (manufactured by Hitachi High-Tech Corporation, TMA7100) under the following measurement conditions. <Measurement conditions> Test equipment: Thermomechanical analyzer (manufactured by Hitachi High-Tech Corporation, TMA7100) Measurement mode: Compression Measurement temperature: -60 to 270 ° C. Heating temperature: 5 ° C. / min Evaluation range: -40 to 120 ° C.

[0083] (1-2) Linear expansion coefficient (M-CTE) of metal member The linear expansion coefficient (M-CTE) of the metal member of the resin-metal composite used to evaluate the heat shock resistance was measured in accordance with JIS Z2285: 2003. The linear expansion coefficient (M-CTE) of the metal member (made of stainless steel (SUS304)) used in the examples was 1.73 × 10 －５ / ℃.

[0084] (2) Heat Shock Resistance Using an injection molding machine SE50-EVA (manufactured by Sumitomo Heavy Industries, Ltd.), as shown in FIG. 4, a metal member 22 (made of stainless steel (SUS304), size: 6 mm x 6 mm x 103 mm) was set in the cavity 31 of the mold 3 for the heat shock resistance evaluation test piece, and the cylinder temperature was 290 ° C. and the mold temperature was 150 ° C. A heat shock resistance evaluation test piece 2 was produced. In FIG. 4, reference numeral 32 denotes a resin inlet. In the heat shock resistance evaluation test piece 2, the resin member 21 was coated on the metal member 22 in a shape with a radius of 10 mm and a length of 85 mm, as shown in FIGS. 2 and 3. In addition, in the cross section of the heat shock resistance evaluation test piece 2 shown in FIG. 3, the minimum thickness of the resin member 21 was 0.76 mm. A weld line 24 was present in the resin member 21 of the heat shock resistance evaluation test piece 2 in the longitudinal direction on the side opposite to the gate portion 23. Using the obtained heat shock resistance evaluation test piece 2, a heat shock test was performed using a small thermal shock device TES-12-A (manufactured by Espec Corporation) under the following measurement conditions. For three heat shock resistance evaluation test pieces 2, the minimum number of cycles at which cracks occurred at the weld line 24 was measured, and the heat shock resistance was evaluated based on the following evaluation criteria. <Measurement conditions> - Conditions for one cycle: 15 minutes at 120°C → 15 minutes at -40°C <Evaluation criteria> A: The minimum number of cycles at which cracks occurred was greater than 500 cycles. B: The minimum number of cycles at which cracks occurred was greater than 300 cycles and not more than 500 cycles. C: The minimum number of cycles at which cracks occurred was greater than 150 cycles and not more than 300 cycles. D: The minimum number of cycles at which cracks occurred was 150 cycles or less.

[0085] (3) Flame Retardancy A combustion test was conducted on a molded product with a wall thickness of 1.6 mm in accordance with the UL94 vertical flame test established by Underwriter Laboratories, Inc., USA. Based on the results of the combustion test, the flame retardancy was evaluated by classifying it into V-0, V-1, V-2, and Vout. The flame retardancy rating of V-0 indicates the best, followed by V-1 and V-2. The worst flame retardancy, not corresponding to any of V-0, V-1, or V-2, was rated as Vout.

[0086] (4) Tracking Resistance In accordance with JIS C2134:2021, the comparative tracking index (CTI) was measured using measurement solution A. Based on the measured CTI value, the tracking resistance was evaluated by classifying it into the following UL Performance Level Categories (PLC) defined by Underwriters Laboratories, Inc., USA. Note that a UL Performance Level Category of 0 indicates the best tracking resistance, and a UL Performance Level Category of 5 indicates the worst tracking resistance. 0: CTI is 600V or more 1: CTI is 400 to 599V 2: CTI is 250 to 399V 3: CTI is 175 to 249V 4: CTI is 100 to 174V 5: CTI is less than 100V

[0087] The evaluation results of the examples and comparative examples are shown in Tables 1 and 2.

[0088]

[0089]

[0090] From the results in Tables 1 and 2, it can be seen that the fiber-reinforced thermoplastic resin composition of the present invention has excellent flame retardancy and, further, excellent heat shock resistance when used as a resin member of a metal-resin composite. Therefore, the fiber-reinforced thermoplastic resin composition of the present invention can be suitably used in the fields of electronics and electrical machinery, automobiles, and household electrical appliances, and in particular, terminal blocks and bus bar members used in control circuit wiring for automotive lithium-ion batteries and electric vehicles, terminal blocks and bus bar members used in panels such as distribution boards, distribution boards, and control panels, terminal blocks and bus bar members used in relay boxes for electric wires used in large machines, junction boxes, solenoid valves, etc.

[0091] 1: Dumbbell-shaped test piece 11: Cutout portion of test piece for measuring MD linear expansion coefficient (MD-CTE) 12: Cutout portion of test piece for measuring TD linear expansion coefficient (TD-CTE) 2: Test piece for evaluating heat shock resistance 21: Resin member (fiber-reinforced resin composition) 22: Metal member 23: Gate portion 24: Position of weld line 3: Mold for test piece for evaluating heat shock resistance 31: Cavity 32: Resin inlet

Claims

1. A fiber-reinforced thermoplastic resin composition comprising a thermoplastic resin composition and glass fibers having a flat cross section, the thermoplastic resin composition comprising 100 parts by mass of a styrene-based resin composition consisting of 75.0 to 94.0 parts by mass of a styrene-based polymer having a syndiotactic structure and a weight-average molecular weight of less than 230,000 and 6.0 to 25.0 parts by mass of a rubber-like elastomer, and 11.0 to 30.0 parts by mass of a bromine-based flame retardant, the content of the glass fibers being 25.0 to 55.0% by mass relative to the total of the thermoplastic resin composition and the glass fibers.

2. The fiber-reinforced thermoplastic resin composition according to claim 1, further comprising 0.5 to 15.0 parts by mass of a flame retardant auxiliary per 100 parts by mass of the styrene-based resin composition.

3. The fiber-reinforced thermoplastic resin composition according to claim 1 or 2, wherein the thermoplastic resin composition further contains 0.3 to 3.0 parts by mass of hydrotalcite per 100 parts by mass of the styrene-based resin composition.

4. The fiber-reinforced thermoplastic resin composition according to any one of claims 1 to 3, further comprising 3.0 to 20.0 parts by mass of magnesium hydroxide per 100 parts by mass of the styrene-based resin composition.

5. A fiber-reinforced thermoplastic resin composition according to any one of claims 1 to 4, wherein the irregular shape ratio of the glass fiber having a flat cross section is 2.0 to 6.

0.

6. A resin-metal composite comprising a resin member made of the fiber-reinforced thermoplastic resin composition according to any one of claims 1 to 5 and a metal member.

7. The resin-metal composite according to claim 6, wherein the metal member is at least one selected from the group consisting of aluminum, stainless steel, copper, titanium, and alloys thereof.

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