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

Abstract

To provide a polybutylene terephthalate resin composition which contains a glass fiber that is excellent in hydrolysis resistance and contains reduced unfibrillated glass fiber bundles.SOLUTION: A polybutylene terephthalate resin composition contains: 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 5 meq / kg or more and 18 meq / kg or less; and a glass fiber (B) 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 also referred to as "PBT resin") has excellent mechanical properties, electrical properties, heat resistance, and moldability. In particular, the addition of glass fibers improves mechanical properties and heat resistance, and therefore it is widely used in various fields such as automobile parts, parts for electrical and electronic equipment, and parts for precision equipment. Such parts are often produced by injection molding, and a glass fiber-reinforced PBT resin composition is used, which is made by kneading PBT resin melted in an extruder, chopped strand glass fibers, and various additives, and processing them into pellets.

[0003] On the other hand, since PBT resin has ester groups in its molecules, it is prone to hydrolysis in high-temperature and high-humidity environments, and improved hydrolysis resistance is always desired for automotive parts that are subject to large environmental changes. For example, PBT resin reinforced with glass fiber is used in the housings of sensors and ECUs that control safety and automatic driving in automotive parts, and since it is compounded with metal parts such as terminals and collars, it may crack due to heat shock. In particular, in a humid and hot environment, PBT resin is hydrolyzed, accelerating cracking.

[0004] It is generally known that in order to improve the hydrolysis resistance of the PBT resin itself, an epoxy resin or a carbodiimide compound is added to reduce the amount of terminal carboxyl groups (see Patent Documents 1 and 2).

[0005] Patent Document 1 shows that for a resin composition consisting of a PBT resin having a terminal carboxyl group amount of 30 meq / kg or less, a carbodiimide compound, a fibrous filler, and an elastomer, when the terminal carboxyl group amount of the PBT resin is taken as 1, the heat shock resistance and hydrolysis resistance are improved by blending 0.3 to 1.5 equivalents of carbodiimide functional groups.

[0006] Patent Document 2 shows that hydrolysis resistance is improved by blending an epoxy compound with a PBT resin having a terminal carboxyl group concentration of 0.1 μeq / g or more and less than 6 μeq / g and an intrinsic viscosity of 0.75 to 1 dL / g.

[0007] It is also 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, an unsaturated carboxylic acid and / or a copolymer of an anhydride of an unsaturated carboxylic acid and 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.

[0008] Meanwhile, for resin pellets used in injection molding, those containing glass fibers are generally prepared in the form of chopped strands, in which multiple glass fibers are bundled together and cut to a length of several millimeters, for ease of feeding during extrusion. However, it is known that glass fiber bundles may not be defibrated during extrusion kneading (Patent Document 5). Patent Document 5 describes a method for preventing glass fiber bundles from not being defibrated during kneading, in which a screw and a die are inserted into the resin flow passage, each with an opening area of ​​38.47 mm. 2 It has been shown that by providing a plurality of flow paths that are less than 40% of the area of ​​the surface to which the openings of the plurality of flow paths belong, it is possible to prevent non-fibrillation. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] International Publication No. 2009 / 150831 [Patent Document 2] JP 2004-277718 A [Patent Document 3] JP 2003-201671 A [Patent Document 4] JP 2015-129073 A [Patent Document 5] International Publication No. 2022 / 202096 Summary of the Invention [Problem to be solved by the invention]

[0010] As mentioned above, although there have been proposals to improve the hydrolysis resistance of PBT resin, it is still insufficient and further improvement is expected. Another issue for glass fiber reinforced PBT resin is how to prevent nozzle clogging of injection molding machines and reduction in strength of molded products caused by unbroken glass fibers.

[0011] 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 containing glass fibers, which has excellent hydrolysis resistance and reduced unbroken glass fiber bundles, a production method thereof, and a resin molded article obtained by molding the resin composition. [Means for solving the problem]

[0012] As a result of intensive research to solve the above problems, the present inventors have found that by using a PBT resin composition containing 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 5 meq / kg or more and 18 meq / kg or less, and glass fibers that have been surface-treated with a sizing agent containing a polymer including structural units derived from carboxylic acid or the like and an epoxy resin, hydrolysis resistance is significantly improved and undisintegrated glass fiber bundles are reduced compared to conventional methods, which led to the completion of the present invention.

[0013] One aspect of the present invention that solves the above problems is as follows. (1) 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 5 meq / kg or more and 18 meq / kg or less; A polybutylene terephthalate resin composition comprising: a polymer containing structural units derived from a carboxylic acid and / or a carboxylic acid anhydride; and glass fibers (B) that have been surface-treated with a bundling agent containing an epoxy resin.

[0014] (2) The polybutylene terephthalate resin composition according to (1), wherein the glass fibers (B) have an average fiber diameter of 3 to 50 μm, and the content of the sizing agent per 100 parts by mass of the glass fibers (B) is 0.1 to 3.0 parts by mass.

[0015] (3) The polybutylene terephthalate resin composition according to (1) or (2) above, further comprising an elastomer (C).

[0016] (4) A resin molded product comprising the polybutylene terephthalate resin composition according to (1) or (2).

[0017] (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 5 meq / kg or more and 18 meq / kg or less, using 1,4-butanediol and / or terephthalic acid obtained by chemical recycling; A method for producing a polybutylene terephthalate resin composition, comprising the step of mixing the polybutylene terephthalate resin (A) with glass fibers (B) that have been surface-treated with a sizing agent that contains a polymer including a structural unit derived from a carboxylic acid and / or a carboxylic acid anhydride and an epoxy resin.

[0018] (6) The method for producing the polybutylene terephthalate resin composition according to (1) or (2) above, comprising: 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 end group content of 5 meq / kg or more and 18 meq / kg or less, obtained by material recycling, and a step of mixing the polybutylene terephthalate resin (A) with glass fiber (B) 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. A method for producing a polybutylene terephthalate resin composition. [Advantages of the Invention]

[0019] According to the present invention, it is possible to provide a polybutylene terephthalate resin composition containing glass fiber, which is excellent in hydrolysis resistance and has a reduced amount of unfibrillated glass fiber bundles, a method for producing the same, and a resin molded article formed by molding the resin composition. [Embodiments for Carrying Out the Invention]

[0020] [PBT Resin Composition] The PBT resin composition of the present embodiment contains 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 end group content of 5 meq / kg or more and 18 meq / kg or less, and glass fiber (B) 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.

[0021] In the PBT resin composition of the present embodiment, by using a PBT resin (A) having a predetermined intrinsic viscosity and a predetermined carboxylic acid end group content and glass fiber (B) surface-treated with a predetermined sizing agent, it is excellent in hydrolysis resistance and has a reduced amount of unfibrillated glass fiber bundles. Hereinafter, each component of the PBT resin composition of the present embodiment will be described.

[0022] [Polybutylene Terephthalate Resin (A)] The PBT resin (A) is a PBT-based 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, but 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.

[0023] The amount of carboxylic acid end groups of the PBT resin (A) is 5 meq / kg or more and 18 meq / kg or less, and 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 addition, the amount of carboxylic acid end groups is set to 5 meq / kg or more in order to ensure the dispersibility of the glass fibers surface-treated with a sizing agent and to avoid the inclusion of undispersed matter. If the amount of carboxylic acid end groups is less than 5 meq / kg, the reactivity between the glass fibers and the PBT resin during melt processing decreases, which reduces the dispersibility of the glass fibers and makes it easier for undispersed matter to be mixed in.

[0024] 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, and more preferably 0.83 dL / g or more and 0.90 dL / g or less. When a PBT resin having an intrinsic viscosity in this range is used, the resulting PBT resin composition has excellent hydrolysis resistance and moldability. When a PBT resin having an intrinsic viscosity of less than 0.70 dL / g is used, the shear stress applied to the glass fiber surface-treated with a sizing agent during melt processing decreases. Therefore, the dispersibility of the glass fiber decreases, and undispersed matter is easily mixed in. When a PBT resin having an intrinsic viscosity of more than 1.10 dL / g is used, the glass fiber breaks during melt processing, causing a decrease in strength, and the melt viscosity increases, causing deterioration in moldability. The intrinsic viscosity (IV) of the PBT resin (A) can also 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 1.0 dL / g with a PBT resin having an intrinsic viscosity of 0.8 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.).

[0029] 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).

[0030] If the intrinsic viscosity and amount of carboxylic acid end groups of PBT resin (A) are within the above 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.

[0031] [Glass Fiber (B)] In the PBT resin composition of this embodiment, the glass fiber (B) is 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. By containing the glass fiber (B), the effect of improving the mechanical strength of the molded product is obtained, and further, the surface treatment with a specific sizing agent provides excellent hydrolysis resistance. Furthermore, the non-fibrillation of the glass fiber caused by the sizing agent can be significantly reduced.

[0032] The type of glass used as the raw material for the glass fiber (B) is not particularly limited, but from the viewpoint of quality, E glass and corrosion-resistant glass containing zirconium element in its composition are preferably used.

[0033] The average fiber diameter of the glass fiber (B) is preferably 3 to 50 μm, more preferably 6 to 15 μm, from the viewpoint of mechanical properties and prevention of gate clogging during injection molding. The average fiber length of the glass fiber (B) is not particularly limited and can be, for example, 0.1 to 20 mm. The average fiber diameter and average fiber length of the glass fiber (B) are values ​​calculated by analyzing an image taken by a CCD camera of the glass fiber after blending in the resin composition and calculating a 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. The blended glass fiber (B) can be obtained by treating it in a thermostatic bath at 600° C. for about 2 to 3 hours.

[0034] The glass fiber (B) may have either a circular or noncircular cross section. 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 are easily obtained, and the decrease in strength due to the tendency to crack due to excessive flatness is easily suppressed.

[0035] The glass fibers (B) may be used alone or in combination of two or more.

[0036] In addition, glass fiber (B) and a non-fibrous inorganic filler may be used in combination. By using glass fiber (B) 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 glass fiber (B) and non-fibrous inorganic filler is not particularly limited, but glass fiber (B) / 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 non-fibrous inorganic filler is 20 mass% or more of glass fiber, better low warpage is easily obtained, and when it is 55 mass% or less, better tensile strength is easily obtained. The combination of glass fiber (B) and non-fibrous inorganic filler is not particularly limited, but examples thereof include combinations of glass fiber (B) and non-fibrous inorganic filler such as glass flakes, mica, and talc.

[0037] Next, the polymer having a structural unit derived from a carboxylic acid and / or a carboxylic anhydride and the epoxy resin contained in the sizing agent used in the surface treatment of the glass fiber (B) will be described below.

[0038] (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, or 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.

[0039] In this 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 resistance is obtained and sufficient adhesion to the surface of the glass fiber is achieved.

[0040] (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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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 molded product.

[0046] 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 glass fibers (B). By containing the sizing agent in an amount of 0.1 to 3.0 parts by mass, hydrolysis resistance can be improved.

[0047] 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.

[0048] In the PBT resin composition of the present embodiment, the glass fiber (B) is contained in an amount of preferably 10 to 100 parts by mass, and more preferably 20 to 80 parts by mass, based on 100 parts by mass of the PBT resin (A).

[0049] [Elastomer (C)] The PBT resin composition of the present embodiment preferably further contains an elastomer (C). By containing the elastomer (C), it is possible to improve the heat shock resistance required when a molded article made of the PBT resin composition is used in an environment where heating and cooling are repeated.

[0050] The elastomer (C) can absorb distortions occurring in molded products by imparting toughness to the PBT resin composition, and is preferably used as a resin that has a small shrinkage rate and / or linear expansion coefficient during molding or heat treatment, as well as good compatibility with the PBT resin (A). Examples of such elastomer (C) include olefin-based elastomers, diene-based elastomers, core-shell-based elastomers, styrene-based elastomers, silicone-based elastomers, and combinations thereof. Among these, olefin-based elastomers and core-shell-based elastomers are preferred because they provide excellent heat shock resistance. In addition, a known compatibilizer may be used in combination to improve the affinity between these elastomers (C) and the PBT resin (A).

[0051] Examples of olefin 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, etc.). Preferred olefin elastomers include EP copolymers, EPD copolymers, and copolymers of olefins and (meth)acrylic monomers, and ethylene ethyl acrylate is particularly preferred. These olefin elastomers can be used alone or in combination of two or more.

[0052] A core-shell elastomer is a polymer in which the core layer is composed of a rubber component (soft component) and the shell layer is composed of a hard component, and the rubber component of the core layer is an acrylic rubber, etc. The rubber component 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).

[0053] When an acrylic rubber is used as the rubber component, a polymer obtained by polymerizing an acrylic monomer such as an alkyl acrylate as a main component is preferred. 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.

[0054] 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.

[0055] 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 such a core-shell elastomer 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.

[0056] [Epoxy compounds] In the PBT resin composition of the present embodiment, an epoxy compound can be used as an additive to further improve hydrolysis resistance. Examples of the epoxy compound in the present 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 200 to 1500 g / equivalent (g / eq).

[0057] In the present embodiment, the epoxy compound is preferably added in an amount of 0.5 to 5 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, hydrolysis resistance can be improved, and when the content is 5 parts by mass or less, the generation of char during molding is suppressed, and unfilled or discoloration due to an increase in viscosity can be suppressed.

[0058] [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 glass fibers (B), 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.

[0059] The PBT resin composition of the present embodiment described above has a reduced amount of unfibrillated glass fiber bundles, and therefore the dispersibility of the glass fibers is improved. In addition, the flowability of the PBT resin composition is in accordance with ISO11443, with a furnace temperature of 260°C, a capillary diameter of 1 mm x 20 mmL, and a shear rate of 1000 sec -1 The melt viscosity measured at is preferably 0.15 kPa·s or more and 0.30 kPa·s or less, more preferably 0.16 kPa·s or more and 0.25 kPa·s or less, and even more preferably 0.17 kPa·s or more and 0.23 kPa·s or less. By setting the melt viscosity at 0.30 kPa·s or less, the flowability required for injection molding can be ensured, the dispersion of glass fibers can be excellent, and glass fiber breakage can be suppressed. Therefore, the PBT resin composition of this embodiment has high strength and excellent appearance. In addition, by setting the melt viscosity at 0.16 kPa·s or more, the non-dispersion of glass fibers can be reduced.

[0060] <Resin molded products> The resin molded product of the present embodiment is produced by molding the PBT resin composition of the present embodiment described above. Therefore, like the PBT resin composition of the present embodiment, it has the effects of significantly improving hydrolysis resistance compared to conventional products and containing no or little unbroken glass fibers.

[0061] 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.

[0062] The resin molded article of this embodiment can be suitably used as a resin composition for molded articles exposed to high temperature and high humidity environments for a long period of time, such as automobiles, trains, and aviation industry applications. In a molded article made of this resin composition, even if it is used for a long period of time under a sufficiently high temperature and high humidity environment, it can be prevented from deteriorating due to hydrolysis, and furthermore, it has excellent fluidity, so it can be used for narrow and thin relays and connectors. In particular, since the undispersed glass fibers are reduced, filling defects due to clogging of thin parts and protrusion of undispersed glass fiber bundles on the molded article surface are reduced. In addition, when an elastomer is blended, the heat shock resistance is improved, so it can be used for electrical components ECUs, housings, sensors, etc. installed around the engine, motor, and battery of an automobile.

[0063] <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 5 meq / kg or more and 18 meq / kg or less, using 1,4-butanediol and / or terephthalic acid obtained by chemical recycling, and a step of mixing the PBT resin (A) with glass fiber (B).

[0064] In addition, the second embodiment includes a step of obtaining a PBT resin (A) obtained by material recycling, the 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 5 meq / kg or more and 18 meq / kg or less, and a step of mixing the PBT resin (A) with glass fiber (B).

[0065] 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 5 meq / kg or more and 18 meq / kg or less can be obtained, there is no limitation on the method for obtaining the PBT resin (A).

[0066] 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.

[0067] 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.

[0068] 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.

[0069] 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 then 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 mechanical properties and improve the appearance of the molded product made of the PBT resin composition.

[0070] In any embodiment, there are no particular limitations 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 5 meq / kg or more and 18 meq / kg or less.

[0071] In the step of mixing components (A) and (B), the method for mixing each component is not particularly limited, and any known method can be used. For example, each component is put into an extruder, melt-kneaded, and pelletized. EXAMPLES

[0072] 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.

[0073] [Examples 1 to 8, Comparative Examples 1 to 6] In each of the Examples and Comparative Examples, the components (A) to (C) were melt-kneaded and extruded in the ratios (parts by mass) shown in Tables 2 to 3 using a 30 mmφ twin-screw extruder (TEX30C, manufactured by Japan Steel Works, Ltd.) with a cylinder temperature of 260°C at the raw material supply section and the 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. For the evaluation of undispersed matter shown below, the components were melt-kneaded and extruded at a screw rotation speed of 70 rpm to obtain pellets made of a PBT resin composition. Details of each component shown in Tables 2 to 3 are shown below.

[0074] (1) PBT resin: (A-1): PBT resin manufactured by Polyplastics Co., Ltd. Intrinsic viscosity: 0.86 dL / g Carboxylic acid end group amount: 12 meq / kg (A-2): 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, and the resulting ISO test piece was crushed in a small crusher. PBT resin. Intrinsic viscosity: 0.89 dL / g, carboxylic acid end group amount: 14 meq / kg. (A-3): Polyplastics Co., Ltd., PBT resin, intrinsic viscosity: 0.91 dL / g, carboxylic acid end group amount: 7 meq / kg (A-4): Polyplastics Co., Ltd., PBT resin, intrinsic viscosity: 0.86 dL / g, carboxylic acid end group amount: 3 meq / kg (A-5): Polyplastics Co., Ltd., PBT resin, intrinsic viscosity: 0.86 dL / g, carboxylic acid end group amount: 20 meq / kg (A-6): Polyplastics Co., Ltd., PBT resin, intrinsic viscosity: 0.66 dL / g, carboxylic acid end group amount: 13 meq / kg

[0075] (4) Glass fiber (B) (B-1) Glass fiber: 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%) (B-2) Glass fiber: E-glass glass fiber, average fiber diameter 13 μm (bundling agent: phenol novolac resin 0.5% by mass) (B-3) Glass fiber: E-glass glass fiber, average fiber diameter 13 μm (bundling agent: copolymer of maleic anhydride, methyl methacrylate and methyl acrylate (0.2 mass%)

[0076] Meanwhile, the components of the sizing agent used in the surface treatment of the glass fibers (B-1) to (B-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 (B-1), the sizing agent is contained in an amount of 0.7 part by mass relative to 100 parts by mass of the glass fiber (B-1).

[0077] [Table 1]

[0078] (5) Elastomer (C) (C-1) Elastomer: Ethylene ethyl acrylate copolymer NUC-6570 manufactured by ENEOS NUC Corporation (C-2) Elastomer: Dow Chemical core-shell elastomer Paraloid EXL-2311 (6) Epoxy compound: Epicoat 1004, manufactured by Mitsubishi Chemical Corporation

[0079] [evaluation] The pellets obtained in each of the Examples and Comparative Examples were used to carry out the following evaluation tests.

[0080] (1) Hydrolysis resistance The PBT resin composition pellets of each of the Examples and Comparative Examples obtained with the compositions shown in Tables 2-3 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 pieces in accordance with ISO3167. The tensile strength of the obtained test pieces was measured in accordance with ISO527-1,2. The measurement results are shown in Tables 2-3. Next, using a PCT processing device (highly accelerated life test device), the test pieces were exposed to 121°C and 100% RH, and the tensile strength was measured after the moist heat test (after 50 hours, 100 hours, and 150 hours), and the strength retention rate before and after the moist heat treatment was calculated. The calculation results are shown in Tables 2-3. (2) Number of unresolved pellets 1 kg of the PBT resin composition pellets of each of the Examples and Comparative Examples obtained with the compositions in Tables 2 to 3 was spread out in a single layer and visually observed, and the number of pellets in which glass fiber lumps were confirmed on the pellet surface or cross section was counted. The measurement results for each composition are shown in Tables 2 to 3. (3) Melt Viscosity The PBT resin composition pellets of each Example and Comparative Example obtained with the composition in Tables 2 to 3 were dried at 140°C for 3 hours, and then subjected to a shear rate of 1000 sec using Capillograph 1B (manufactured by Toyo Seiki Seisakusho Co., Ltd.) in accordance with ISO11443, with a furnace temperature of 260°C, a capillary diameter of 1 mm x 20 mmL, and a shear rate of 1000 sec. -1 A melt viscosity of 0.30 kPa s or less is considered to be low and has good fluidity. (4) Heat shock resistance The PBT resin composition pellets of each Example and Comparative Example obtained with the composition of Tables 2-3 were dried at 140 ° C for 3 hours, and then the resin temperature was 260 ° C, the mold temperature was 65 ° C, the injection time was 25 seconds, and the cooling time was 10 seconds. The insert molded product was manufactured by insert injection molding into a mold for molding a test piece (a mold for inserting an iron core of 18 mm in length, 18 mm in width, and 30 mm in height into a rectangular column of 22 mm in length, 22 mm in width, and 51 mm in height) so that the minimum thickness of a part of the resin part was 1 mm. The insert molded product obtained was subjected to a heat shock resistance test using a thermal shock tester, in which the process of heating at 140 ° C for 1 hour and 30 minutes, cooling to -40 ° C for 1 hour and 30 minutes, and then heating to 140 ° C was performed as one cycle, and the number of cycles until the insert molded product cracked was measured, and the heat shock resistance was evaluated.

[0081] [Table 2]

[0082] [Table 3]

[0083] It can be seen from Tables 2 and 3 that in Examples 1 to 8, good evaluation results were obtained for hydrolysis resistance and defibration of glass fiber bundles. On the other hand, Comparative Example 1, which differs from Example 1 only in that glass fiber (B-2) surface-treated with a sizing agent of phenol novolac resin was used, and Comparative Example 2, which differs from Example 1 only in that glass fiber (B-3) surface-treated with a sizing agent containing only a copolymer of a copolymer of maleic anhydride, methyl methacrylate, and methyl acrylate were used, had poor hydrolysis resistance. Comparative Example 4 using a PBT resin (A-5) with a high amount of carboxylic acid terminal groups, and Comparative Example 6 using a PBT resin (A-4) with a low amount of carboxylic acid terminal groups, were poor in hydrolysis resistance. Furthermore, Comparative Example 3, in which a PBT resin (A-4) having a low amount of carboxylic acid terminal groups was used, and Comparative Example 5, in which a PBT resin (A-6) having a low intrinsic viscosity was used, were inferior in the defibration properties of glass fiber bundles. Incidentally, Examples 5 to 8 in which the elastomer (C) was added were excellent in heat shock resistance as well as in hydrolysis resistance and defibration property of glass fiber bundles.

Claims

1. 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 5 meq / kg or more and 18 meq / kg or less; glass fibers (B) that have been surface-treated with a sizing agent containing a polymer including structural units derived from a carboxylic acid and / or a carboxylic acid anhydride and an epoxy resin; 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. 2. The polybutylene terephthalate resin composition according to claim 1, wherein the glass fibers (B) have an average fiber diameter of 3 to 50 μm, and the content of the sizing agent relative to 100 parts by mass of the glass fibers (B) is 0.1 to 3.0 parts by mass.

3. The polybutylene terephthalate resin composition according to claim 1 or 2, further comprising an elastomer (C).

4. A resin molded article made from the polybutylene terephthalate resin composition according to claim 1 or 2.

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 5 meq / kg or more and 18 meq / kg or less, using 1,4-butanediol and / or terephthalic acid obtained by chemical recycling; The method includes a step of mixing the polybutylene terephthalate resin (A) with glass fibers (B) that have been surface-treated with a sizing agent containing a polymer including structural units 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 5 meq / kg or more and 18 meq / kg or less; The method includes a step of mixing the polybutylene terephthalate resin (A) with glass fibers (B) that have been surface-treated with a sizing agent containing a polymer including structural units 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.