Polybutylene terephthalate resin composition and method for producing the same, and resin molded article

Abstract

To provide a polybutylene terephthalate resin composition which enables molding of a resin molded article that is excellent in both alkali resistance and hydrolysis resistance.SOLUTION: A polybutylene terephthalate resin composition contains, with respect to 100 pts.mass of a polybutylene terephthalate resin (A) having an intrinsic viscosity of 0.70 dL / g or more and 1.10 dL / g or less, and a carboxylic acid terminal content of 18 meq / kg or less, 10 to 30 pts.mass of an elastomer (B), 0.5 to 3.0 pts.mass of a silicone compound (C) having a kinematic viscosity at 25°C of 3,000 to 10,000 cSt, and 10 to 100 pts.mass of an inorganic filler (D) which is surface-treated with a sizing agent containing a polymer including a structural unit derived from a carboxylic acid and / or a carboxylic acid anhydride and an epoxy resin.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a polybutylene terephthalate resin composition, a method for producing the same, and a resin molded article. [Background technology]

[0002] Polybutylene terephthalate resin (hereinafter referred to as "PBT resin") is a crystalline thermoplastic resin that has excellent mechanical strength, electrical properties, and other various characteristics, and is therefore used as an engineering plastic in a wide range of applications, including automobiles, electrical and electronic devices, etc. However, PBT resin tends to have low long-term durability in alkaline solutions, and its usage environments and applications are limited. For example, some parts may be used in places where they come into contact with toilet cleaners, bathtub cleaners, bleaches, snow-melting agents, etc. These agents contain alkaline components such as sodium hydroxide, sodium hypochlorite, sodium percarbonate, calcium chloride, etc., and therefore PBT resin molded products are exposed to an alkaline atmosphere. If a PBT resin molded product is exposed to such an alkaline atmosphere for a long period of time while being subjected to excessive strain due to screwing, metal press-fitting, crimping, etc., the effects of both the strain and the alkaline components cause so-called environmental stress cracking, which causes cracks in the molded product, and this has been problematic. Furthermore, the strength and toughness of PBT resin can decrease not only in alkaline environments but also in high-temperature and high-humidity environments due to hydrolysis of the ester groups in the molecule, and there has always been a demand for improved resistance to moisture and heat.

[0003] Patent Document 1 describes a PBT resin composition capable of forming molded articles having excellent alkali resistance and heat shock resistance, the PBT resin composition comprising a PBT resin, 0.5 to 1.8 mass % of a silicone compound having a kinetic viscosity of 1000 to 10000 cSt at 25°C based on the total mass of the PBT resin composition, and 5 to 20 mass % of an olefin-based elastomer based on the total mass of the PBT resin composition.

[0004] Patent Document 2 describes a thermoplastic polyester resin composition obtained by blending (A) a thermoplastic polyester resin with (B) an impact resistance imparting agent, (C) a silicone compound and / or a fluorine-based compound, (D) an inorganic filler, and (E) a polyfunctional compound. It also discloses that a molded article having excellent alkali resistance can be obtained by using a thermoplastic polyester resin composition obtained by blending a predetermined amount of (A) a PBT resin as the thermoplastic polyester resin, (B) an ethylene-ethyl acrylate copolymer and a methyl methacrylate-butyl acrylate copolymer as an impact resistance imparting agent (EEA-g-BA / MMA), an acrylic core-shell polymer, an epoxidized styrene-butadiene-styrene copolymer (ESBS), or an ethylene-glycidyl methacrylate copolymer and a methyl methacrylate copolymer (EGMA-g-MMA) as an impact resistance imparting agent, (C) a silicone oil-containing silicone powder as the silicone compound and / or a fluorine-based compound, (D) glass fiber as the inorganic filler, and (E) an epoxy resin as the polyfunctional compound.

[0005] On the other hand, it is known that the hydrolysis resistance of glass fibers themselves can be improved by using an epoxy resin as a sizing agent (see Patent Documents 3 and 4). Patent Document 3 shows the use of glass fibers that have been surface-treated with a sizing agent containing, as essential components, a copolymer of an unsaturated carboxylic acid and / or an anhydride of an unsaturated carboxylic acid with an unsaturated monomer, and an epoxy resin. Patent Document 4 shows that surface-treated glass fibers containing a novolac-type epoxy resin have excellent long-term heat resistance. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] International Publication No. 2018 / 047662 [Patent Document 2] International Publication No. 2000 / 078867 [Patent Document 3] JP 2003-201671 A [Patent Document 4] JP 2015-129073 A Summary of the Invention [Problem to be solved by the invention]

[0007] As described above, there has been a demand for further improvement in the alkali resistance and hydrolysis resistance of polyester resins as product life spans become longer.

[0008] The present invention has been made in consideration of the above-mentioned problems in the conventional art, and an object of the present invention is to provide a polybutylene terephthalate resin composition capable of molding a resin molded article having excellent both alkali resistance and hydrolysis resistance, a production method thereof, and a resin molded article obtained by molding the resin composition. [Means for solving the problem]

[0009] As a result of intensive research into solving the above problems, the present inventors have found that by using a PBT resin composition containing predetermined amounts of a PBT resin having a carboxylic acid end group amount of 18 meq / kg or less, an elastomer, a silicone compound having a kinetic viscosity of 3000 to 10000 cSt, and glass fibers that have been surface-treated with a sizing agent containing a polymer containing a structural unit derived from carboxylic acid, etc., and an epoxy resin, both alkali resistance and hydrolysis resistance are significantly improved compared to conventional methods, and have completed the present invention.

[0010] One aspect of the present invention that solves the above problems is as follows. (1) for 100 parts by mass of a polybutylene terephthalate resin (A) having an intrinsic viscosity of 0.70 dL / g or more and 1.10 dL / g or less and a carboxylic acid terminal group amount of 18 meq / kg or less, 10 to 30 parts by mass of an elastomer (B), 0.5 to 30 parts by mass of a silicone compound (C) having a kinematic viscosity at 25°C of 3,000 to 10,000 cSt, and 10 to 100 parts by mass of an inorganic filler (D) that has been surface-treated with a sizing agent containing a polymer containing a structural unit derived from a carboxylic acid and / or a carboxylic acid anhydride and an epoxy resin, A polybutylene terephthalate resin composition comprising:

[0011] (2) The polybutylene terephthalate resin composition according to (1) above, which contains 0.5 to 3.0 parts by mass of an aromatic carbodiimide and / or an epoxy compound per 100 parts by mass of the polybutylene terephthalate resin (A).

[0012] (3) The polybutylene terephthalate resin composition according to (1) or (2), wherein the inorganic filler (D) is fibrous and has an average fiber diameter of 3 to 50 μm, and the content of the sizing agent per 100 parts by mass of the inorganic filler (D) is 0.1 to 3.0 parts by mass.

[0013] (4) A resin molded product obtained by molding the polybutylene terephthalate resin composition according to (1) or (2) above, which is used for a part that comes into contact with an alkaline solution.

[0014] (5) A method for producing the polybutylene terephthalate resin composition according to (1) or (2), comprising the steps of: A step of obtaining a polybutylene terephthalate resin (A) having an intrinsic viscosity of 0.70 dL / g or more and 1.10 dL / g or less and a carboxylic acid terminal group amount of 18 meq / kg or less, using 1,4-butanediol and / or terephthalic acid obtained by chemical recycling; a step of mixing, relative to 100 parts by mass of the polybutylene terephthalate resin (A), 10 to 30 parts by mass of an elastomer (B), 0.5 to 3.0 parts by mass of a silicone compound (C) having a kinetic viscosity of 3,000 to 10,000 cSt at 25°C, and 10 to 100 parts by mass of an inorganic filler (D) that has been surface-treated with a sizing agent containing a polymer including a structural unit derived from a carboxylic acid and / or a carboxylic acid anhydride, and an epoxy resin.

[0015] (6) A method for producing the polybutylene terephthalate resin composition according to (1) or (2), comprising the steps of: A step of obtaining a polybutylene terephthalate resin (A) obtained by material recycling, the polybutylene terephthalate resin (A) having an intrinsic viscosity of 0.70 dL / g or more and 1.10 dL / g or less and a carboxylic acid terminal group amount of 18 meq / kg or less; a step of mixing, relative to 100 parts by mass of the polybutylene terephthalate resin (A), 10 to 30 parts by mass of an elastomer (B), 0.5 to 3.0 parts by mass of a silicone compound (C) having a kinetic viscosity of 3,000 to 10,000 cSt at 25°C, and 10 to 100 parts by mass of an inorganic filler (D) that has been surface-treated with a sizing agent containing a polymer including a structural unit derived from a carboxylic acid and / or a carboxylic acid anhydride, and an epoxy resin. Effect of the Invention

[0016] According to the present invention, it is possible to provide a polybutylene terephthalate resin composition having excellent alkali resistance and hydrolysis resistance, a method for producing the same, and a resin molded article obtained by molding the resin composition. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] <Polybutylene terephthalate resin composition> The PBT resin composition of the present embodiment contains 100 parts by mass of a PBT resin (A) having an intrinsic viscosity of 0.70 dL / g or more and 1.10 dL / g or less and a carboxylic acid terminal group amount of 18 meq / kg or less, 10 to 30 parts by mass of an elastomer (B), 0.5 to 3.0 parts by mass of a silicone compound (C) having a kinetic viscosity of 3000 to 10000 cSt at 25°C, and 10 to 100 parts by mass of an inorganic filler (D) that has been surface-treated with a sizing agent containing a polymer including a structural unit derived from a carboxylic acid and / or a carboxylic acid anhydride and an epoxy resin.

[0018] The PBT resin composition of the present embodiment has excellent alkali resistance by containing a predetermined amount of elastomer (B) and silicone compound (C).In addition, the composition has excellent hydrolysis resistance by using a PBT resin having an intrinsic viscosity of 0.70 dL / g or more and 1.10 dL / g or less and a carboxylic acid end group amount of 18 meq / kg or less, and by containing a polymer containing a structural unit derived from a carboxylic acid and / or a carboxylic acid anhydride in the sizing agent of the inorganic filler (D). Each component of the PBT resin composition of the present embodiment will be described below.

[0019] [Polybutylene terephthalate (PBT) resin (A)] The PBT resin (A) is a polybutylene terephthalate resin obtained by polycondensation of a dicarboxylic acid component containing at least terephthalic acid or its ester-forming derivative (C1-6 alkyl ester, acid halide, etc.) and a glycol component containing at least an alkylene glycol having 4 carbon atoms (1,4-butanediol) or its ester-forming derivative (acetylated product, etc.). The PBT resin (A) is not limited to a homopolybutylene terephthalate resin, and may be a copolymer containing 60 mol % or more (particularly 75 mol % or more and 95 mol % or less) of butylene terephthalate units. In this embodiment, 1,4-butanediol and terephthalic acid or terephthalic acid alkyl ester, which are raw materials for the PBT resin, may be derived from either fossil resources or biomass resources.

[0020] The amount of carboxylic acid end groups in the PBT resin (A) is 18 meq / kg or less, preferably 2 meq / kg or more and 15 meq / kg or less, and more preferably 5 meq / kg or more and 13 meq / kg or less. By using a PBT resin having a carboxylic acid end group amount in this range, the resulting PBT resin composition is less susceptible to strength reduction due to hydrolysis in a humid and hot environment. In order to ensure adhesion to an inorganic filler surface-treated with a sizing agent, the amount of carboxylic acid end groups is preferably 2 meq / kg or more. If the amount of carboxylic acid end groups is less than 2 meq / kg, adhesion to glass fibers is reduced, resulting in a reduction in strength.

[0021] The intrinsic viscosity (IV) of the PBT resin (A) is 0.70 dL / g or more and 1.10 dL / g or less, preferably 0.80 dL / g or more and 1.00 dL / g or less, more preferably 0.83 dL / g or more and 0.95 dL / g or less. When a PBT resin having an intrinsic viscosity in such a range is used, the obtained PBT resin composition has excellent hydrolysis resistance and moldability. In addition, the intrinsic viscosity can be adjusted by blending PBT resins having different intrinsic viscosities. For example, a PBT resin having an intrinsic viscosity of 0.85 dL / g can be prepared by blending a PBT resin having an intrinsic viscosity of 1.00 dL / g with a PBT resin having an intrinsic viscosity of 0.80 dL / g. The intrinsic viscosity (IV) of the PBT resin (A) can be measured, for example, in o-chlorophenol at a temperature of 35°C.

[0022] In the PBT resin (A), examples of dicarboxylic acid components (comonomer components) other than terephthalic acid and its ester-forming derivatives include C8-14 aromatic dicarboxylic acids such as isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, and 4,4'-dicarboxydiphenyl ether; C4-16 alkanedicarboxylic acids such as succinic acid, adipic acid, azelaic acid, and sebacic acid; C5-10 cycloalkanedicarboxylic acids such as cyclohexanedicarboxylic acid; and ester-forming derivatives of these dicarboxylic acid components (C1-6 alkyl ester derivatives, acid halides, etc.). These dicarboxylic acid components can be used alone or in combination of two or more.

[0023] Among these dicarboxylic acid components, C8-12 aromatic dicarboxylic acids such as isophthalic acid, and C6-12 alkanedicarboxylic acids such as adipic acid, azelaic acid, and sebacic acid are more preferred.

[0024] In the PBT resin (A), examples of glycol components (comonomer components) other than 1,4-butanediol include C2-10 alkylene glycols such as ethylene glycol, propylene glycol, trimethylene glycol, 1,3-butylene glycol, hexamethylene glycol, neopentyl glycol, and 1,3-octanediol; polyoxyalkylene glycols such as diethylene glycol, triethylene glycol, and dipropylene glycol; alicyclic diols such as cyclohexanedimethanol and hydrogenated bisphenol A; aromatic diols such as bisphenol A and 4,4'-dihydroxybiphenyl; C2-4 alkylene oxide adducts of bisphenol A, such as 2-mol ethylene oxide adducts of bisphenol A and 3-mol propylene oxide adducts of bisphenol A; and ester-forming derivatives of these glycols (acetylated products, etc.). These glycol components can be used alone or in combination of two or more.

[0025] Among these glycol components, C2-6 alkylene glycols such as ethylene glycol and trimethylene glycol, polyoxyalkylene glycols such as diethylene glycol, and alicyclic diols such as cyclohexanedimethanol are more preferred. Examples of comonomer components that can be used in addition to the dicarboxylic acid component and the glycol component include aromatic hydroxycarboxylic acids such as 4-hydroxybenzoic acid, 3-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, and 4-carboxy-4'-hydroxybiphenyl; aliphatic hydroxycarboxylic acids such as glycolic acid and hydroxycaproic acid; C3-12 lactones such as propiolactone, butyrolactone, valerolactone, and caprolactone (ε-caprolactone, etc.); and ester-forming derivatives of these comonomer components (C1-6 alkyl ester derivatives, acid halides, acetylated products, etc.).

[0026] Any of the polybutylene terephthalate copolymers obtained by copolymerizing the comonomer components described above can be suitably used as the PBT resin (A). In addition, a homopolybutylene terephthalate polymer and a polybutylene terephthalate copolymer may be used in combination as the PBT resin (A).

[0027] If the intrinsic viscosity and amount of carboxylic acid end groups of PBT resin (A) are within the above-mentioned ranges, market recovered products can be used (material recycling). In addition, PBT resins produced by decomposing 1,4-butanediol, terephthalic acid, etc. from PBT resin waste to the monomer level (chemical recycling) and polycondensing the obtained raw materials can also be used. The form of the manufacturing method using such PBT resins will be described later.

[0028] [Elastomer (B)] The PBT resin composition of the present embodiment contains 100 parts by mass of the PBT resin (A) and 10 to 30 parts by mass of the elastomer (B).

[0029] As the elastomer (B), a resin that not only has a small shrinkage rate and / or linear expansion coefficient during molding or heat treatment, but also has a processing temperature close to that of the PBT resin (A) and is highly compatible can be preferably used. Examples of such elastomer (B) include olefin-based elastomers, diene-based elastomers, core-shell-based elastomers, styrene-based elastomers, silicone-based elastomers, and combinations thereof. Among them, when one or more types selected from olefin-based elastomers, core-shell-based elastomers, and styrene-based elastomers are used, the alkali resistance can be improved by alleviating distortion of the resin molded product.

[0030] (Olefin elastomer) Examples of olefin-based elastomers include ethylene-propylene copolymers (EP copolymers), ethylene-butene copolymers, ethylene-octene copolymers, ethylene-propylene-diene copolymers (EPD copolymers), ethylene-propylene-butene copolymers, ethylene-vinyl acetate copolymers, copolymers containing at least one unit selected from EP copolymers and EPD copolymers, copolymers of olefins and (meth)acrylic monomers, ethylene-ethyl acrylate copolymers, ethylene-glycidyl methacrylate copolymers, α-olefin·α,β-unsaturated carboxylic acid (ester)·α,β-unsaturated carboxylic acid glycidyl ester terpolymers, and ethylene-based copolymers obtained by copolymerizing ethylene (co)polymers with maleic anhydride or glycidyl methacrylate. Preferred olefin-based elastomers include EP copolymers, EPD copolymers, and copolymers of olefins and (meth)acrylic monomers, with ethylene ethyl acrylate being particularly preferred. These olefin-based elastomers can be used alone or in combination of two or more.

[0031] (Core-shell elastomer) The core-shell elastomer is a polymer in which the core layer is made of a rubber component (soft component) and the shell layer is made of a hard component. The rubber component of the core layer is preferably an acrylic rubber from the viewpoint of heat resistance. The acrylic rubber used in the core layer preferably has a glass transition temperature (Tg) of less than 0°C (e.g., -10°C or less), more preferably -20°C or less (e.g., -180°C or more and -25°C or less), and particularly preferably -30°C or less (e.g., -150°C or more and -40°C or less).

[0032] The acrylic rubber used as the rubber component is preferably a polymer obtained by polymerizing an acrylic monomer such as an alkyl acrylate as a main component. The alkyl acrylate used as a monomer for the acrylic rubber is preferably a C1-C12 alkyl ester of acrylic acid such as butyl acrylate, and more preferably a C2-C6 alkyl ester of acrylic acid.

[0033] The acrylic rubber may be a homopolymer or a copolymer of an acrylic monomer. When the acrylic rubber is a copolymer of an acrylic monomer, it may be a copolymer of acrylic monomers, or a copolymer of an acrylic monomer and another unsaturated bond-containing monomer. When the acrylic rubber is a copolymer, it may be a copolymer of a crosslinkable monomer.

[0034] A vinyl polymer is preferably used for the shell layer. The vinyl polymer is obtained by polymerizing or copolymerizing at least one monomer selected from, for example, an aromatic vinyl monomer, a vinyl cyanide monomer, a methacrylic acid ester monomer, and an acrylic acid ester monomer. The core layer and the shell layer of the core-shell elast using an acrylic rubber may be bonded by graft copolymerization. This graft copolymerization is obtained by adding a graft crossing agent that reacts with the shell layer during polymerization of the core layer, if necessary, to give a reactive group to the core layer, and then forming the shell layer. When a silicone rubber is used as the graft crossing agent, an organosiloxane having a vinyl bond or an organosiloxane having a thiol is used, and preferably acryloxysiloxane, methacryloxysiloxane, or vinylsiloxane is used.

[0035] (styrene elastomer) Examples of the styrene-based elastomer include acrylonitrile-styrene copolymer, acrylonitrile-butadiene-styrene copolymer, styrene-butadiene copolymer, styrene-butadiene-styrene copolymer, styrene-isoprene-styrene copolymer, styrene-ethylene-butadiene-styrene copolymer, acrylonitrile-styrene-epoxy group-containing vinyl copolymer, etc., and these can be used alone or in combination of two or more kinds.

[0036] The content of the elastomer (B) is 10 to 30 parts by mass relative to 100 parts by mass of the PBT resin (A). If the content of the elastomer (B) is less than 10 parts by mass, the resin molded product will crack due to increased stress, while if it exceeds 30 parts by mass, the resin molded product will become too flexible, decreasing its strength and rigidity.

[0037] [Silicone compounds (C)] The PBT resin composition of the present embodiment contains 100 parts by mass of PBT resin (A) and 0.5 to 3.0 parts by mass of a silicone compound (C) having a kinetic viscosity of 3,000 to 10,000 cSt at 25° C. By containing the silicone compound (C), the composition has high alkali resistance.

[0038] Preferred examples of the silicone compound (C) include pure silicone resins such as dimethylpolysiloxane, methylphenylpolysiloxane, and diphenylpolysiloxane, which are generally known as silicone oils, and modified silicones obtained by reacting pure silicone resins with modifying resins such as alkyd resins, polyester resins, acrylic resins, and epoxy resins, but are not limited thereto.

[0039] Also, a cured silicone powder that has absorbed silicone oil (hereinafter, sometimes referred to as "silicone oil-absorbed cured silicone powder") may be used. For example, the silicone oil-absorbed cured silicone powder may be obtained by blending 0.5 to 80% by weight of silicone oil in advance with fine powder cured silicone, absorbing the silicone oil, and powdering the silicone oil by any method. For example, a conventionally known silicone rubber or silicone gel may be used as the silicone that absorbs silicone oil to form the cured silicone powder.

[0040] Examples of silicone oils include those represented by the following general formula (1): In the following general formula (1), R is a substituted or unsubstituted monovalent hydrocarbon group or a hydroxyl group, and n is an integer. R3SiO[R2SiO] n SiR3...General formula (1) In the above general formula (1), R is a substituted or unsubstituted monovalent hydrocarbon group or a hydroxyl group. Examples of the substituted or unsubstituted monovalent hydrocarbon group include alkyl groups such as methyl, ethyl, and propyl; alkenyl groups such as vinyl and allyl; aralkyl groups such as cycloalkyl and β-phenylethyl; 3,3,3-trifluoropropyl, 3-mercaptopropyl, 3-aminopropyl, and 3-glycidoxypropyl groups.

[0041] In this embodiment, the kinetic viscosity of the silicone compound (C) at 25° C. is 3000 to 10000 cSt (10 to 100 cm 2 / s). If the kinetic viscosity is less than 3000 cSt, the resin composition will have insufficient water repellency, and if it exceeds 10000 cSt, the dispersibility of the resin composition will decrease. The kinetic viscosity is preferably 3000 to 8000 cSt, more preferably 3000 to 6000 cSt. When using the silicone oil-absorbed cured silicone powder described above, the silicone oil to be absorbed may have a kinetic viscosity in the above range.

[0042] The silicone compound (C) may be used alone or in combination of two or more kinds.

[0043] The content of the silicone compound (C) is 0.5 to 3.0 parts by mass, preferably 0.6 to 2.5 parts by mass, and more preferably 0.8 to 2.0 parts by mass, relative to 100 parts by mass of the PBT resin (A). If the content of the silicone compound (C) is less than 0.5% by weight, the effect of improving alkali resistance is poor, and if it exceeds 3.0% by mass, problems occur due to exudation from the resin molded product.

[0044] [Inorganic filler (D)] The PBT resin composition of the present embodiment contains 10 to 100 parts by mass of an inorganic filler (D) that has been surface-treated with a sizing agent containing a polymer containing a structural unit derived from a carboxylic acid and / or a carboxylic anhydride and an epoxy resin, relative to 100 parts by mass of a PBT resin (A). By containing the inorganic filler (D), the effect of improving the mechanical strength of the molded product is obtained, and further, the surface treatment with a predetermined sizing agent provides excellent hydrolysis resistance.

[0045] The inorganic filler (D) may be in the form of either a fibrous inorganic filler or a non-fibrous inorganic filler, with a fibrous inorganic filler being preferred.

[0046] (fibrous inorganic filler) Examples of fibrous inorganic fillers include glass fibers, carbon fibers, silica fibers, silica-alumina fibers, zirconia fibers, boron nitride fibers, silicon nitride fibers, boron fibers, potassium titanate fibers, and metal fibers (e.g., stainless steel, aluminum, titanium, copper, brass, etc.). Representative examples of fibrous inorganic fillers include glass fibers and carbon fibers, and glass fibers are preferably used in terms of availability and cost. The type of glass used as the raw material for glass fibers is not particularly limited, but E glass and corrosion-resistant glass containing zirconium elements in the composition are preferably used in terms of quality.

[0047] The average fiber diameter of the fibrous inorganic filler is preferably 3 to 50 μm, more preferably 6 to 15 μm, from the viewpoint of mechanical properties and gate clogging during injection molding. The average fiber length of the fibrous inorganic filler is not particularly limited, and can be, for example, 0.1 to 20 mm. The average fiber diameter and average fiber length of the fibrous filler are values ​​calculated by analyzing an image taken by a CCD camera of the fibrous filler before it is mixed into the resin composition, and calculating the weighted average. For example, they can be calculated using a dynamic image analysis method / particle (state) analyzer PITA-3 manufactured by Seishin Enterprise Co., Ltd.

[0048] As the fibrous inorganic filler, either one having a circular cross section or one having a noncircular cross section can be used. Examples of noncircular cross sections include oval, elliptical, and cocoon shapes. The irregularity ratio (major axis diameter:minor axis diameter) of the noncircular cross section is not particularly limited, but is preferably 1.5:1 to 6:1, more preferably 2:1 to 5:1, and even more preferably 2.5:1 to 4:1. When the irregularity ratio is in the range of 1.5:1 to 6:1, the effects of dimensional stability and warpage reduction due to the flattening of the cross section can be easily obtained, and the decrease in strength due to the excessive flatness that makes the material more susceptible to cracking can also be easily suppressed.

[0049] (Non-fibrous inorganic filler) The shape of the non-fibrous inorganic filler is not particularly limited, and examples thereof include granular, ellipsoidal, spindle-shaped, plate-shaped, scaly, irregular, etc. Specific examples of the non-fibrous inorganic filler include silicates such as mica, talc, quartz, calcium silicate, aluminum silicate, kaolin, clay, diatomaceous earth, and bentonite; carbon-based materials such as carbon black and graphite; metal carbonates such as calcium carbonate and magnesium carbonate; metal sulfates such as zinc sulfate, calcium sulfate, and barium sulfate; metal oxides such as zinc oxide, iron oxide, titanium oxide, antimony trioxide, and alumina; glass flakes, glass beads, milled glass fibers, glass balloons, glass powder, and the like; and other materials such as magnesium hydroxide, boehmite, spherical silica, ferrite, silicon carbide, silicon nitride, boron nitride, and various metal powders, but are not limited thereto. From the viewpoint of improving low warpage properties, it is preferable to contain a plate-like or scaly inorganic filler such as mica, glass flakes, or talc, and it is more preferable to contain at least a plate-like inorganic filler such as mica or talc.

[0050] The inorganic filler (D) may be used alone or in combination of two or more kinds.

[0051] In addition, a fibrous inorganic filler and a non-fibrous inorganic filler may be used in combination. By using a fibrous inorganic filler and a non-fibrous inorganic filler in combination, it is possible to achieve both low warpage and mechanical properties such as tensile strength. The ratio of the fibrous inorganic filler and the non-fibrous inorganic filler is not particularly limited, but the fibrous inorganic filler / non-fibrous inorganic filler (mass ratio) is preferably 80 / 20 to 45 / 55, more preferably 75 / 25 to 55 / 45, and even more preferably 70 / 30 to 60 / 40. When the content of the non-fibrous inorganic filler is 20% by mass or more of the inorganic filler, better low warpage is easily obtained, and when it is 55% by mass or less, better tensile strength is easily obtained. The combination of the fibrous inorganic filler and the non-fibrous inorganic filler is not particularly limited, but examples thereof include combinations of a fibrous inorganic filler such as glass fiber or carbon fiber with a non-fibrous inorganic filler such as glass flake, mica or talc, and from the viewpoint of hydrolysis resistance, it is particularly preferable to combine glass fiber with glass flake.

[0052] Next, in the inorganic filler (D), the polymer having a structural unit derived from a carboxylic acid and / or a carboxylic acid anhydride, which is contained in the sizing agent used in the surface treatment, and the epoxy resin will be described below.

[0053] (Polymers Having Structural Units Derived from Carboxylic Acids and / or Carboxylic Acid Anhydrides) In the polymer having a structural unit derived from a carboxylic acid and / or a carboxylic acid anhydride (hereinafter, simply referred to as a "polymer"), the carboxylic acid may be an unsaturated carboxylic acid such as acrylic acid, methacrylic acid, fumaric acid, maleic acid, succinic acid, cinnamic acid, itaconic acid, mesaconic acid, citraconic acid, etc. These may have a substituent. Among them, acrylic acid, methacrylic acid, and maleic acid are preferable. In addition, the carboxylic acid anhydride may be an anhydride of an unsaturated carboxylic acid such as maleic anhydride, itaconic anhydride, succinic anhydride, phthalic anhydride, glutaric anhydride, dodecenylsuccinic anhydride, and chlorendic anhydride. The above polymers may be homopolymers in which each carboxylic acid or carboxylic anhydride is polymerized alone, or may be copolymers in which two or more carboxylic acids or carboxylic anhydrides are copolymerized.

[0054] In the present embodiment, the weight average molecular weight of the above polymer is not particularly limited, but is particularly preferably 10,000 to 1,000,000. When the weight average molecular weight is within the range of 10,000 to 1,000,000, sufficient hydrolysis property is obtained and sufficient adhesion to the surface of the inorganic filler is obtained.

[0055] (Epoxy resin) Examples of epoxy resins include glycidyl ether type epoxy resins, glycidyl ester type epoxy resins (diglycidyl phthalate, diglycidyl tetrahydrophthalate, diglycidyl hexahydrophthalate, dimethylglycidyl phthalate, dimethylglycidyl hexahydrophthalate, dimer acid glycidyl ester, aromatic diglycidyl ester, cycloaliphatic diglycidyl ester, etc.), glycidyl amine type epoxy resins (tetraglycidyldiaminodiphenylmethane, triglycidyl-paraaminophenol, triglycidyl-methamine, etc.), and the like. nonphenol, diglycidyl toluidine, tetraglycidyl metaxylylenediamine, diglycidyl tribromoaniline, tetraglycidyl bisaminomethylcyclohexane, etc.), heterocyclic epoxy resins (triglycidyl isocyanurate (TGIC), hydantoin type epoxy resins, etc.), cyclic aliphatic epoxy resins (vinylcyclohexene dioxide, dicyclopentadiene oxide, alicyclic diepoxy acetal, alicyclic diepoxy adipate, alicyclic diepoxy carboxylate, etc.), epoxidized polybutadiene, etc.

[0056] Glycidyl ether type epoxy resins include glycidyl ethers of polyhydroxy compounds [glycidyl ethers of aromatic polyhydroxy compounds such as bisphenol type epoxy resins (e.g., bisphenol A type, bisphenol AD ​​type, or bisphenol F type epoxy resins), and resorcin type epoxy resins; aliphatic epoxy resins (glycidyl ethers of alkylene glycols, polyoxyalkylene glycols, and the like)], novolac type epoxy resins (phenol novolac type, cresol novolac type epoxy resins, and the like), and the like.

[0057] Among epoxy resins, aromatic epoxy resins (such as bisphenol-type epoxy resins, resorcin-type epoxy resins, and phenol novolac-type epoxy resins) and cyclic aliphatic epoxy resins are preferred. Among them, glycidyl ether-type aromatic epoxy resins, such as bisphenol-type epoxy resins and phenol novolac-type epoxy resins, are preferred.

[0058] The epoxy equivalent of the epoxy resin may be, for example, about 100 to 1600 g / eq, preferably about 100 to 800 g / eq, and more preferably about 150 to 500 g / eq.

[0059] The number average molecular weight of the epoxy resin may be, for example, about 200 to 50,000, preferably about 300 to 10,000, and more preferably about 400 to 6,000.

[0060] In this embodiment, the mass ratio (X / Y) of the polymer (X) to the epoxy resin (Y) in the sizing agent is preferably 0.001 to 1.500 from the viewpoint of improving the mechanical strength of the resin molded product.

[0061] The sizing agent is preferably contained in an amount of 0.1 to 3.0 parts by mass, and more preferably 0.3 to 2.5 parts by mass, per 100 parts by mass of the inorganic filler (D). By containing the sizing agent in an amount of 0.1 to 3.0 parts by mass, hydrolysis resistance can be improved.

[0062] In addition to the above components, the bundling agent may contain components such as urethane resin, silane coupling agent, lubricant, nonionic surfactant, antistatic agent, etc., and the mixing ratio of each component may be determined as necessary. The urethane resin contributes to the bundling and dispersibility of the glass fiber, and is obtained from polyisocyanate and polyol, etc. As the silane coupling agent, aminosilane, epoxysilane, chlorosilane, mercaptosilane, vinylsilane, acrylicsilane, etc. can be used. As the lubricant, fatty acid amide, quaternary ammonium salt, etc. can be used. As the nonionic surfactant, synthetic alcohol, natural alcohol, fatty acid ester, etc. can be used.

[0063] The inorganic filler (D) is contained in an amount of 10 to 100 parts by mass, and preferably 20 to 80 parts by mass, per 100 parts by mass of the PBT resin (A). If the content of the inorganic filler (D) is less than 10 parts by mass, the effect of improving mechanical strength cannot be obtained, whereas if it exceeds 100 parts by mass, toughness decreases and cracks caused by an alkaline solution tend to occur.

[0064] In the PBT resin composition of the present embodiment, in order to further improve hydrolysis resistance, it is preferable to contain 0.5 to 3.0 parts by mass of an aromatic carbodiimide and / or an epoxy compound per 100 parts by mass of the PBT resin (A). Each of these will be explained below.

[0065] [Aromatic carbodiimide compounds] The aromatic carbodiimide compound is a compound having a carbodiimide group (-N=C=N-) in the molecule and an aromatic main chain. Among the carbodiimide compounds, the aromatic carbodiimide compound is preferable in terms of excellent heat resistance and moist heat resistance.

[0066] Examples of the aromatic carbodiimide compound include diphenylcarbodiimide, di-2,6-dimethylphenylcarbodiimide, N-triyl-N'-phenylcarbodiimide, di-p-nitrophenylcarbodiimide, di-p-aminophenylcarbodiimide, di-p-hydroxyphenylcarbodiimide, di-p-chlorophenylcarbodiimide, di-p-methoxyphenylcarbodiimide, di-3,4-dichlorophenylcarbodiimide, di-2,5-dichlorophenylcarbodiimide, di-o-chlorophenylcarbodiimide, p-fluorophenylcarbodiimide, mono- or dicarbodiimide compounds such as p-phenylene-bis-di-o-triylcarbodiimide, p-phenylene-bis-dicyclohexylcarbodiimide, p-phenylene-bis-di-p-chlorophenylcarbodiimide, and ethylene-bis-diphenylcarbodiimide; and poly(4,4'-diphenylmethanecarbodiimide), poly(3,5'-dimethyl-4,4'-biphenylmethanecarbodiimide), poly(p-phenylenecarbodiimide), poly(m-phenylenecarbodiimide), poly(3,5'-dimethyl-4,4'-diphenyl Examples of the polycarbodiimide compounds include poly(1,3-diisopropylphenylenecarbodiimide), poly(naphthylenecarbodiimide), poly(1,3-diisopropylphenylenecarbodiimide), poly(1-methyl-3,5-diisopropylphenylenecarbodiimide), poly(1,3,5-triethylphenylenecarbodiimide) and poly(triisopropylphenylenecarbodiimide). Two or more of these may be used in combination.

[0067] The number average molecular weight of the aromatic carbodiimide compound is preferably at least 3000. By setting the number average molecular weight within the above range, it is possible to prevent the generation of gas or odor when the residence time is long during melt-kneading or molding of the thermoplastic resin.

[0068] The content of the aromatic carbodiimide compound is preferably 0.5 to 3.0 parts by mass relative to 100 parts by mass of the PBT resin (A). When the content is 0.5 parts by mass or more, the hydrolysis resistance can be improved, and when the content is 3.0 parts by mass or less, the decrease in fluidity is suppressed and the generation of gel components or charred materials during compounding (when producing the resin composition) or molding is suppressed.

[0069] [Epoxy compounds] Examples of the epoxy compound in this embodiment include aromatic epoxy compounds such as biphenyl type epoxy compounds, bisphenol A type epoxy compounds, phenol novolac type epoxy compounds, and cresol novolac type epoxy compounds. The epoxy compound may be used in any combination of two or more compounds. The epoxy equivalent is preferably 600 to 1500 g / equivalent (g / eq).

[0070] In the present embodiment, the amount of the epoxy compound added is preferably 0.5 to 3.0 parts by mass per 100 parts by mass of the PBT resin (A). When the content is 0.5 parts by mass or more, the hydrolysis resistance can be improved, and when the content is 5 parts by mass or less, the generation of char during molding processing can be suppressed, and unfilled and discoloration due to an increase in viscosity can be suppressed.

[0071] [Other ingredients] The PBT resin composition of the present embodiment may contain other components as necessary. Examples of other components include, but are not limited to, inorganic fillers other than the inorganic filler (D), antioxidants, weather stabilizers, molecular weight regulators, ultraviolet absorbers, antistatic agents, dyes, pigments, lubricants, crystallization accelerators, crystal nucleating agents, near-infrared absorbers, flame retardants, flame retardant assistants, organic fillers, and colorants.

[0072] <Resin molded products> The resin molded product of this embodiment is formed by molding the PBT resin composition of this embodiment described above, and is used for parts that come into contact with an alkaline solution. That is, like the PBT resin composition of this embodiment, the resin molded product of this embodiment has the effect of significantly improving alkali resistance and hydrolysis resistance compared to conventional products. Therefore, even when used for parts that come into contact with an alkaline solution, it is possible to exhibit alkali resistance performance and suppress the occurrence of cracks. Examples of parts that come into contact with an alkaline solution include the housing of a millimeter wave radar, the housing of an ECU case, the housing of a sensor case such as a sonar sensor, and the housing of a motor part such as an electric parking brake.

[0073] The method for producing a resin molded article using the PBT resin composition of the present embodiment is not particularly limited, and a known method can be adopted. For example, the PBT resin composition of the present embodiment can be put into an extruder, melt-kneaded and pelletized, and the pellets can be put into an injection molding machine equipped with a predetermined mold and injection molded to produce the resin molded article.

[0074] The resin molded article of the present embodiment can be suitably used as a resin composition for molded articles that are exposed to high temperature and high humidity environments for long periods of time, such as for automobiles, trains, and the aviation industry. Molded articles made of this resin composition can be used for connectors and the like because they can be prevented from deteriorating due to hydrolysis even when used for a long period of time in a sufficiently high temperature and high humidity environment.

[0075] <Method of producing polybutylene terephthalate resin composition> There are two methods for producing the PBT resin composition of the present embodiment, a first method and a second method, and either method is one method for producing the PBT resin composition of the present embodiment described above. In the first embodiment, the method includes a step of obtaining a PBT resin (A) having an intrinsic viscosity of 0.70 dL / g or more and 1.10 dL / g or less and a carboxylic acid terminal group amount of 18 meq / kg or less, using 1,4-butanediol and / or terephthalic acid obtained by chemical recycling, and a step of mixing, with respect to 100 parts by mass of the PBT resin (A), 10 to 30 parts by mass of an elastomer (B), 0.5 to 3.0 parts by mass of a silicone compound (C) having a kinetic viscosity of 3000 to 10000 cSt at 25°C, and 10 to 100 parts by mass of an inorganic filler (D) that has been surface-treated with a sizing agent containing a polymer containing a structural unit derived from a carboxylic acid and / or a carboxylic acid anhydride, and an epoxy resin.

[0076] In addition, in the second embodiment, the method includes a step of obtaining a PBT resin (A) obtained by material recycling, the PBT resin having an intrinsic viscosity of 0.70 dL / g or more and 1.10 dL / g or less and a carboxylic acid terminal group amount of 18 meq / kg or less, and a step of mixing 100 parts by mass of the PBT resin (A) with 10 to 30 parts by mass of an elastomer (B), 0.5 to 3.0 parts by mass of a silicone compound (C) having a kinetic viscosity of 3000 to 10000 cSt at 25°C, and 10 to 100 parts by mass of an inorganic filler (D) that has been surface-treated with a sizing agent containing a polymer containing a structural unit derived from a carboxylic acid and / or a carboxylic acid anhydride and an epoxy resin.

[0077] In the above-mentioned first and second embodiments, the PBT resin (A) is obtained by utilizing chemical recycling and material recycling, respectively, but the production of the PBT resin composition of the above-mentioned embodiment is not limited to the production methods according to the first and second embodiments. That is, as long as a PBT resin having an intrinsic viscosity of 0.70 dL / g or more and 1.10 dL / g or less and a carboxylic acid terminal group amount of 18 meq / kg or less can be obtained, there is no limitation on the method for obtaining the PBT resin (A).

[0078] The first and second forms are different in the process of obtaining the PBT resin (A). That is, in the first form, the PBT resin (A) is obtained using 1,4-butanediol and / or terephthalic acid obtained by chemical recycling, whereas in the second form, the PBT resin (A) is obtained by material recycling.

[0079] In both the first and second forms, PBT resin, which is waste plastic, can be reused, which contributes to saving natural resources and reducing the environmental burden.

[0080] In the first form, PBT resin (A) is produced by decomposing 1,4-butanediol, terephthalic acid, etc. from PBT resin waste etc. to the monomer level (chemical recycling) and polycondensing the obtained raw material. In chemical recycling, PBT resin and alcohols are filled into a reaction vessel and heated to depolymerize the alcohols under supercritical conditions, and 1,4-butanediol and terephthalic acid can be recovered.

[0081] In the second embodiment, the PBT resin (A) is obtained by material recycling. That is, as long as the intrinsic viscosity and the amount of carboxylic acid end groups are within the above-mentioned ranges, market-recovered products can be used. Market-recovered products can be pulverized using a pulverizer such as a single-screw pulverizer, a twin-screw pulverizer, a triple-screw pulverizer, or a cutter mill, and used. The pulverized products can also be melt-kneaded using a single-screw extruder or a twin-screw extruder, and granulated to be used as pellets. In addition, a stainless steel filter can be set on the breaker plate during melt-kneading to remove foreign matter. Since foreign matter is the starting point of destruction, removing the foreign matter can maintain the alkali resistance and mechanical properties of the molded product made of the PBT resin composition and improve the appearance.

[0082] In any embodiment, there is no particular limitation on the manufacturing method as long as the step of obtaining PBT resin (A) can obtain a PBT resin having an intrinsic viscosity of 0.70 dL / g or more and 1.10 dL / g or less and a carboxylic acid terminal group amount of 18 meq / kg or less.

[0083] In the step of mixing the components (A) to (D), the method for mixing the components is not particularly limited, and any known method can be used. For example, the components are fed into an extruder, melt-kneaded, and pelletized. EXAMPLES

[0084] The present embodiment will be described in more detail below with reference to examples, but the present embodiment is not limited to the following examples.

[0085] [Examples 1 to 10, Comparative Examples 1 to 7] In each of the Examples and Comparative Examples, components (A) to (D) were melt-mixed and extruded in the ratios (parts by mass) shown in Tables 2 to 3 using a 30 mmφ twin-screw extruder (TEX30C, manufactured by The Japan Steel Works, Ltd.) with a cylinder temperature of 260°C at the raw material supply section and die tip, and 220 to 260°C between them, at a discharge rate of 15 kg / h and a screw rotation speed of 130 rpm, to obtain pellets made of a PBT resin composition. Details of each component shown in Tables 2 to 3 are shown below.

[0086] (1) Polybutylene terephthalate resin (A) (A-1): Polyplastics Co., Ltd., PBT resin (intrinsic viscosity: 0.86 dL / g, carboxylic acid end group amount: 12 meq / kg) (A-2): PBT resin polycondensed with biomass-derived 1,4-butanediol and terephthalic acid, and titanium tetrabutoxide as a catalyst (intrinsic viscosity: 0.86 dL / g, carboxylic acid end group amount: 12 meq / kg) (A-3): Polyplastics Co., Ltd.'s DURANEX 500FP was dried at 140°C for 3 hours, and then a 1A type ISO test piece (width 10 mm, thickness 4 mmt) conforming to ISO3167 was produced using a FANUC injection molding machine "ROBOSHOT S-2000i 100B" at a cylinder temperature of 260°C and a mold temperature of 80°C. The resulting ISO test piece was then crushed in a small crusher to produce PBT resin (intrinsic viscosity: 0.89 dL / g, carboxylic acid end group amount: 15 meq / kg). (A-4): Polyplastics Co., Ltd., PBT resin (intrinsic viscosity: 0.86 dL / g, carboxylic acid end group amount: 20 meq / kg) (A-5): Polyplastics Co., Ltd., PBT resin (intrinsic viscosity: 0.69 dL / g, carboxylic acid end group amount: 24 meq / kg)

[0087] (2) Elastomer (B) (B-1) Ethylene-ethyl acrylate copolymer (ethylene content 75% by mass, melting point 91°C) (B-2) Acrylic core-shell polymer (Dow Chemical Japan, Paraloid EXL2311) (B-3) Styrene-based elastomer (Kuraray Co., Ltd., Septon 4055)

[0088] (3) Silicone compounds (C) (C-1) Dimethylpolysiloxane, kinematic viscosity at 25°C: 100 cSt (C-2) Dimethylpolysiloxane, kinematic viscosity at 25°C: 5000cSt (C-3) Dimethylpolysiloxane, kinematic viscosity at 25°C 10,000 cSt (C-4) Dimethylpolysiloxane, kinematic viscosity at 25°C 100,000 cSt

[0089] (4) Inorganic filler (D) Glass fiber (D-1): E-glass glass fiber, average fiber diameter 13 μm (bundling agent: phenol novolac resin 0.5 mass%, copolymer of maleic anhydride, methyl methacrylate and methyl acrylate 0.2 mass%) Glass fiber (D-2): E-glass glass fiber, average fiber diameter 13 μm (bundling agent: phenol novolac resin 0.5% by mass) Glass fiber (D-3): E-glass glass fiber, average fiber diameter 13 μm (bundling agent: 0.2% by mass of copolymer of maleic anhydride, methyl methacrylate and methyl acrylate)

[0090] Meanwhile, the components of the sizing agent used in the surface treatment of the glass fibers (D-1) to (D-3) are shown in Table 1. The values ​​in Table 1 indicate the content (mass%) of each component relative to the entire glass fiber. In the glass fiber (D-1), the sizing agent was contained in an amount of 0.7 parts by mass relative to 100 parts by mass of the glass fiber (D-1).

[0091] [Table 1]

[0092] (5) Epoxy compound: Epicoat 1004, manufactured by Mitsubishi Chemical Corporation (6) Carbodiimide compound: Aromatic polycarbodiimide, Stabaxol P-100, manufactured by LANXESS AG (7) Carbon black: Mitsubishi Chemical Corporation, Carbon Black #960B

[0093] [evaluation] The pellets obtained in each of the Examples and Comparative Examples were used to carry out the following evaluation tests. (1) Alkali resistance Pellets made with the compositions shown in Tables 2 and 3 were dried at 140°C for 3 hours, and then injection molded at a cylinder temperature of 260°C and a mold temperature of 80°C to produce a molded piece in the shape of a plate with a thickness of 1 mm and a side of 80 mm, and with a weld part. Next, this molded piece was cut into a strip of 10 mm width and 80 mm length so that the weld part was located approximately in the center in the longitudinal direction, to prepare a test piece. The prepared test pieces were fixed to a jig in a bent state, so that a bending strain of 1.0% was constantly applied to the welded portion. In this state, the jig was immersed in a 10% by mass aqueous solution of sodium hydroxide, and left to stand at an ambient temperature of 23°C, and the test pieces were observed at specific time intervals to see if cracks occurred. The evaluation was performed using three test pieces for each of the pellets of the examples and comparative examples, and the time it took for cracks to occur in at least one of the three test pieces was confirmed. Tables 2 to 3 show the evaluation results 25 hours, 50 hours, and 100 hours after the start of immersion. A means that no cracks occurred in any of the three test pieces, and B means that cracks occurred in at least one of the three test pieces.

[0094] (2) Hydrolysis resistance Pellets prepared with the compositions shown in Tables 2 and 3 were dried at 140°C for 3 hours, and then injection molded at a cylinder temperature of 260°C and a mold temperature of 80°C to prepare 1A type tensile test specimens in accordance with ISO3167. The tensile strength of the obtained test specimens was measured in accordance with ISO527-1,2. The measurement results are shown in Tables 2 and 3. Next, using a PCT processing device (highly accelerated life test device), the test specimens were exposed to 121°C and 100% RH, and the tensile strength was measured after the moist heat test (after 25 hours, 50 hours, and 100 hours), and the strength retention rate before and after the moist heat treatment was calculated. The calculation results are shown in Table 2.

[0095] [Table 2]

[0096] [Table 3]

[0097] It can be seen from Tables 2 and 3 that in Examples 1 to 10, good evaluation results were obtained for both alkali resistance and hydrolysis resistance. On the other hand, Comparative Example 2, which differs from Example 1 only in that no silicone compound (C) was used, and Comparative Examples 4 and 6, in which the kinetic viscosity of the silicone compound used was outside the numerical range specified in this embodiment, had poor alkali resistance. Moreover, Comparative Example 1, which differed from Example 1 only in that glass fibers (D-2) that had been surface-treated with a sizing agent containing only an epoxy resin were used, was inferior in hydrolysis resistance. Furthermore, Comparative Example 3, which differs from Example 1 only in that it used glass fibers (D-3) that had been surface-treated with a sizing agent containing only a copolymer of maleic anhydride, methyl methacrylate, and methyl acrylate, had poor hydrolysis resistance. Furthermore, Comparative Examples 5 and 7, which used a PBT resin having a low intrinsic viscosity (A-5) and a PBT resin having a high amount of carboxylic acid terminal groups (A-4), were poor in hydrolysis resistance.

Claims

1. per 100 parts by mass of a polybutylene terephthalate resin (A) having an intrinsic viscosity of 0.70 dL / g or more and 1.10 dL / g or less and a carboxylic acid terminal group amount of 18 meq / kg or less, 10 to 30 parts by mass of elastomer (B), 0.5 to 3.0 parts by mass of a silicone compound (C) having a kinematic viscosity at 25°C of 3,000 to 10,000 cSt, and 10 to 100 parts by mass of an inorganic filler (D) that has been surface-treated with a sizing agent containing a polymer containing structural units derived from a carboxylic acid and / or a carboxylic acid anhydride and an epoxy resin, Including, The polymer containing structural units derived from a carboxylic acid and / or a carboxylic acid anhydride includes a copolymer of maleic anhydride, methyl methacrylate, and methyl acrylate.

2. The polybutylene terephthalate resin composition according to claim 1, comprising 0.5 to 3.0 parts by mass of an aromatic carbodiimide and / or an epoxy compound per 100 parts by mass of the polybutylene terephthalate resin (A).

3. 3. The polybutylene terephthalate resin composition according to claim 1, wherein the inorganic filler (D) is fibrous and has an average fiber diameter of 3 to 50 μm, and the content of the sizing agent is 0.1 to 3.0 parts by mass per 100 parts by mass of the inorganic filler (D).

4. A resin molded article obtained by molding the polybutylene terephthalate resin composition according to claim 1 or 2, which is used as a part that comes into contact with an alkaline solution.

5. A method for producing the polybutylene terephthalate resin composition according to claim 1 or 2, A step of obtaining a polybutylene terephthalate resin (A) having an intrinsic viscosity of 0.70 dL / g or more and 1.10 dL / g or less and a carboxylic acid terminal group amount of 18 meq / kg or less, using 1,4-butanediol and / or terephthalic acid obtained by chemical recycling; the method includes a step of mixing 100 parts by mass of the polybutylene terephthalate resin (A) with 10 to 30 parts by mass of an elastomer (B), 0.5 to 3.0 parts by mass of a silicone compound (C) having a kinematic viscosity of 3,000 to 10,000 cSt at 25°C, and 10 to 100 parts by mass of an inorganic filler (D) that has been surface-treated with a sizing agent containing a polymer including a structural unit derived from a carboxylic acid and / or a carboxylic acid anhydride and an epoxy resin, A method for producing a polybutylene terephthalate resin composition, wherein the polymer containing structural units derived from the carboxylic acid and / or carboxylic acid anhydride contains a copolymer of maleic anhydride, methyl methacrylate, and methyl acrylate.

6. A method for producing the polybutylene terephthalate resin composition according to claim 1 or 2, A step of obtaining a polybutylene terephthalate resin (A) obtained by material recycling, which has an intrinsic viscosity of 0.70 dL / g or more and 1.10 dL / g or less and a carboxylic acid terminal group amount of 18 meq / kg or less; the method includes a step of mixing 100 parts by mass of the polybutylene terephthalate resin (A) with 10 to 30 parts by mass of an elastomer (B), 0.5 to 3.0 parts by mass of a silicone compound (C) having a kinematic viscosity of 3,000 to 10,000 cSt at 25°C, and 10 to 100 parts by mass of an inorganic filler (D) that has been surface-treated with a sizing agent containing a polymer including a structural unit derived from a carboxylic acid and / or a carboxylic acid anhydride and an epoxy resin, A method for producing a polybutylene terephthalate resin composition, wherein the polymer containing structural units derived from the carboxylic acid and / or carboxylic acid anhydride contains a copolymer of maleic anhydride, methyl methacrylate, and methyl acrylate.