Polybutylene terephthalate resin composition and insert molded article

Abstract

To provide a glass fiber-reinforced PBT resin composition having superior hydrolysis resistance and heat shock resistance relative to traditional ones.SOLUTION: Disclosed is a polybutylene terephthalate resin composition comprising: a polybutylene terephthalate resin (A); glass fibers (B) which have been surface-treated with a sizing agent containing an epoxy resin and a polymer that includes a structural unit derived from a carboxylic acid and / or a carboxylic acid anhydride; an elastomer (C); and an epoxidized natural oil (D), wherein the content of the epoxidized natural oil is 2.0-8.0 pts.mass with respect to 100 pts.mass of the polybutylene terephthalate resin (A).SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a polybutylene terephthalate resin composition and an insert molded product.

Background Art

[0002] Polybutylene terephthalate resin (hereinafter also referred to as "PBT resin") is excellent in mechanical properties, electrical properties, heat resistance, and moldability. In particular, since mechanical properties and heat resistance are improved by adding glass fiber, it is widely used in various fields such as automotive parts, parts for electric and electronic equipment, and parts for precision equipment. Such parts are often produced by injection molding, and a glass fiber-reinforced PBT resin composition obtained by kneading molten PBT resin, chopped strand-like glass fiber, and various additives in an extruder and processing them into pellets is used.

[0003] On the other hand, since PBT resin has an ester group in its molecule, hydrolysis easily occurs in a high-temperature and high-humidity environment, and in automotive parts where environmental changes are large, improvement of hydrolysis resistance is always desired. For example, in automotive parts, PBT resin reinforced with glass fiber or the like is used for the housings of sensors and ECUs that control safety and autonomous driving, etc., and since it is combined with metal parts such as terminals and collars, cracking may occur due to heat shock. Particularly in a humid heat environment, hydrolysis of the PBT resin promotes cracking.

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

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

[0006] Patent Document 2 shows that the hydrolysis resistance is improved by blending an epoxy compound into 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] Also, it is known that the hydrolysis resistance of glass fiber itself can be improved by using an epoxy resin as a sizing agent (see Patent Documents 3 to 4). Patent Document 3 shows that glass fiber surface-treated with a sizing agent containing a copolymer of an unsaturated carboxylic acid and / or an anhydride of an unsaturated carboxylic acid and an unsaturated monomer and an epoxy resin as essential components is used. Further, Patent Document 4 shows that surface-treated glass fiber containing a novolac-type epoxy resin is excellent in long-term heat resistance.

[0008] Furthermore, Patent Document 5 shows that by blending an epoxidized natural oil, a non-crystalline resin, and a fibrous reinforcing material into a thermoplastic polyester resin, excellent hydrolysis resistance can be achieved and elution under a wet heat environment can be suppressed.

Prior Art Documents

Patent Documents

[0009]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Summary of the Invention

Problems to be Solved by the Invention

[0010] As described above, although proposals have been made to improve the hydrolysis resistance and heat shock resistance of PBT resins, they are still not sufficient and further improvement is expected.

[0011] The present invention has been made in view of the above-described conventional problems, and an object thereof is to provide a glass fiber-reinforced PBT resin composition and an insert molded article having improved hydrolysis resistance and heat shock resistance as compared with the prior art.

Means for Solving the Problems

[0012] As a result of intensive studies to solve the above problems, the present inventors have found that hydrolysis resistance and heat shock resistance are significantly improved as compared with the prior art by blending PBT resin, glass fibers surface-treated with a sizing agent containing a polymer containing a structural unit derived from a carboxylic acid or the like and an epoxy resin, an elastomer, and an epoxidized natural oil, and have completed the present invention.

[0013] One aspect of the present invention for solving the above problems is as follows. (1) A polybutylene terephthalate resin (A), Glass fibers (B) surface-treated with a sizing agent containing a polymer containing a structural unit derived from a carboxylic acid and / or carboxylic anhydride and an epoxy resin, An elastomer (C), An epoxidized natural oil (D), and A polybutylene terephthalate resin composition in which the content of the epoxidized natural oil is 2.0 to 8.0 parts by mass with respect to 100 parts by mass of the polybutylene terephthalate resin (A).

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

[0015] (3) The epoxidized natural oil (D) is epoxidized linseed oil or epoxidized soybean oil. The polybutylene terephthalate resin composition according to (1) or (2).

[0016] (4) The elastomer (C) is an olefin-based elastomer or a core-shell elastomer. The polybutylene terephthalate resin composition according to any one of (1) to (3).

[0017] (5) An insert molded article having the polybutylene terephthalate resin composition according to any one of (1) to (4) and an insert member.

Advantages of the Invention

[0018] According to the present invention, it is possible to provide a glass fiber-reinforced polybutylene terephthalate resin composition and an insert molded article having improved hydrolysis resistance and heat shock resistance compared to the conventional ones.

Embodiments for Carrying Out the Invention

[0019] <PBT Resin Composition> The PBT resin composition of this embodiment contains a PBT resin (A), glass fibers (B) surface-treated with a sizing agent containing a polymer containing structural units derived from a carboxylic acid and / or a carboxylic anhydride and an epoxy resin, an elastomer (C), and an epoxidized natural oil (D). And the content of the epoxidized natural oil is 2.0 to 8.0 parts by mass with respect to 100 parts by mass of the polybutylene terephthalate resin (A).

[0020] In the PBT resin composition of the present embodiment, it contains glass fiber (B) surface-treated with a sizing agent containing PBT resin (A), a polymer containing a structural unit derived from carboxylic acid or the like, an epoxy resin, an elastomer (C), and epoxidized natural oil (D). The combination of these components can significantly improve hydrolysis resistance and heat shock resistance. Hereinafter, each component of the PBT resin composition of the present embodiment will be described.

[0021] [Polybutylene terephthalate resin (A)] The PBT resin (A) is a PBT-based resin obtained by polycondensing 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. Also, in the present embodiment, 1,4-butanediol, which is a raw material of the PBT resin, and terephthalic acid or terephthalic acid alkyl ester may be derived from either fossil resources or biomass resources.

[0022] The amount of carboxylic acid end groups of the PBT resin (A) is preferably 5 meq / kg or more and 30 meq / kg or less, and more preferably 5 meq / kg or more and 20 meq / kg or less. By using a PBT resin having an end carboxyl group amount within such a range, the resulting PBT resin composition is less likely to suffer a strength reduction due to hydrolysis in a wet heat environment.

[0023] The intrinsic viscosity (IV) of the PBT resin (A) is preferably 0.70 dL / g or more and 1.10 dL / g or less, more preferably 0.80 dL / g or more and 1.00 dL / g or less, and still more preferably 0.83 dL / g or more and 0.90 dL / g or less. When using a PBT resin having an intrinsic viscosity within such a range, the resulting PBT resin composition will be excellent in hydrolysis resistance and moldability. Also, PBT resins having different intrinsic viscosities can be blended to adjust the intrinsic viscosity. 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 and 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.

[0024] In the PBT resin (A), examples of the dicarboxylic acid component (comonomer component) 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, 4,4'-dicarboxydiphenyl ether; C4-16 alkanedicarboxylic acids such as succinic acid, adipic acid, azelaic acid, 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.

[0025] 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 preferable.

[0026] 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, 1,3-octanediol; polyoxyalkylene glycols such as diethylene glycol, triethylene glycol, dipropylene glycol; alicyclic diols such as cyclohexanedimethanol, hydrogenated bisphenol A; aromatic diols such as bisphenol A, 4,4'-dihydroxybiphenyl; C2-4 alkylene oxide adducts of bisphenol A such as bisphenol A ethylene oxide 2 mol adduct, bisphenol A propylene oxide 3 mol adduct; or ester-forming derivatives (such as acetylated products) of these glycols. These glycol components can be used alone or in combination of two or more.

[0027] Among these glycol components, C2-6 alkylene glycols such as ethylene glycol, trimethylene glycol, polyoxyalkylene glycols such as diethylene glycol, or alicyclic diols such as cyclohexanedimethanol are more preferable. 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, 4-carboxy-4'-hydroxybiphenyl; aliphatic hydroxycarboxylic acids such as glycolic acid, hydroxycaproic acid; C3-12 lactones such as propiolactone, butyrolactone, valerolactone, caprolactone (ε-caprolactone, etc.); and ester-forming derivatives of these comonomer components (C1-6 alkyl ester derivatives, acid halides, acetylated products, etc.).

[0028] All of the polybutylene terephthalate copolymers obtained by copolymerizing the comonomer components described above can be suitably used as the PBT resin (A). Further, as the PBT resin (A), a homopolybutylene terephthalate polymer and a polybutylene terephthalate copolymer may be used in combination.

[0029] Market recycled products can be used as the PBT resin (A) (material recycling). Also, PBT resin 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.

[0030] [Glass fiber (B)] In the PBT resin composition of the present 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 can be obtained, and further, it is excellent in hydrolysis resistance due to surface treatment with a predetermined sizing agent.

[0031] 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 or corrosion-resistant glass containing zirconium element in the composition is preferably used.

[0032] The average fiber diameter of the glass fiber (B) is preferably 3 to 50 μm, more preferably 6 to 15 μm, from the viewpoints 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 weighted average by analyzing an image taken with a CCD camera for the glass fiber after being blended in the resin composition. For example, they can be calculated using a dynamic image analysis method / particle (state) analyzer PITA-3 manufactured by Seishin Enterprise Co., Ltd. The glass fiber (B) after blending can be obtained, for example, by treating it in a constant temperature bath at 600 °C for about 2 to 3 hours.

[0033] As the glass fiber (B), either those having a circular cross-section or those having a non-circular cross-section can be used. Examples of the non-circular cross-section include an oval shape, an elliptical shape, a cocoon shape, etc. The shape ratio (major axis diameter: minor axis diameter) of the non-circular 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 shape ratio is in the range of 1.5:1 to 6:1, effects such as dimensional stability and warpage reduction due to flattening of the cross-section are easily obtained, and a decrease in strength due to excessive flattening and easy cracking can also be easily suppressed.

[0034] The glass fiber (B) may be used alone or in combination of two or more.

[0035] Further, the glass fiber (B) and a non-fibrous inorganic filler may be used in combination. By using the glass fiber (B) and the 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 glass fiber (B) to the non-fibrous inorganic filler is not particularly limited, but the 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 the non-fibrous inorganic filler is 20% by mass or more of the glass fiber, better low warpage can be easily obtained, and when it is 55% by mass or less, better tensile strength can be easily obtained. Examples of the combination of the glass fiber (B) and the non-fibrous inorganic filler are not particularly limited, but include combinations of the glass fiber (B) and non-fibrous inorganic fillers such as glass flakes, mica, and talc.

[0036] Next, in the glass fiber (B), the polymer having a structural unit derived from a carboxylic acid and / or carboxylic anhydride contained in the sizing agent used for surface treatment and the epoxy resin will be described below.

[0037] (Polymer having a structural unit derived from a carboxylic acid and / or carboxylic anhydride) In a polymer having a structural unit derived from a carboxylic acid and / or carboxylic anhydride (hereinafter also simply referred to as "polymer"), examples of the carboxylic acid include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, fumaric acid, maleic acid, succinic acid, cinnamic acid, itaconic acid, mesaconic acid, citraconic acid, etc. These may have substituents. Among them, acrylic acid, methacrylic acid, and maleic acid are preferred. Examples of the carboxylic anhydride include anhydrides of unsaturated carboxylic acids such as maleic anhydride, itaconic anhydride, succinic anhydride, phthalic anhydride, glutaric anhydride, dodecenyl succinic anhydride, and chlorendic anhydride. Each of the above polymers may be a homopolymer in which each carboxylic acid or carboxylic anhydride is polymerized alone, or a copolymer in which two or more carboxylic acids or carboxylic anhydrides are copolymerized.

[0038] In the present embodiment, the weight average molecular weight of the above polymer is not particularly limited, but a range of 10,000 to 1,000,000 is particularly preferred. When the weight average molecular weight is within the range of 10,000 to 1,000,000, sufficient hydrolysis resistance can be obtained and sufficient adhesion to the surface of the glass fiber can be achieved.

[0039] (Epoxy resin) Examples of the epoxy resin include glycidyl ether type epoxy resins, glycidyl ester type epoxy resins (such as diglycidyl phthalate, diglycidyl tetrahydrophthalate, diglycidyl hexahydrophthalate, dimethyl glycidyl phthalate, dimethyl glycidyl hexahydrophthalate, dimer acid glycidyl ester, aromatic diglycidyl ester, cycloaliphatic diglycidyl ester, etc.), glycidyl amine type epoxy resins (such as tetraglycidyl diaminodiphenylmethane, triglycidyl - para - aminophenol, triglycidyl - meta - aminophenol, diglycidyl toluidine, tetraglycidyl metaxylylenediamine, diglycidyl tribromoaniline, tetraglycidyl bisaminomethylcyclohexane, etc.), heterocyclic epoxy resins (such as triglycidyl isocyanurate (TGIC), hydantoin type epoxy resins, etc.), cycloaliphatic epoxy resins (such as vinylcyclohexene dioxide, dicyclopentadiene oxide, alicyclic diepoxy acetal, alicyclic diepoxy adipate, alicyclic diepoxy carboxylate, etc.), epoxidized polybutadiene, and the like.

[0040] The glycidyl ether type epoxy resins include glycidyl ethers of polyhydroxy compounds [glycidyl ethers of aromatic polyhydroxy compounds such as bisphenol type epoxy resins (for example, bisphenol A type, bisphenol AD type, or bisphenol F type epoxy resins, etc.), resorcin type epoxy resins, etc.; aliphatic epoxy resins (such as glycidyl ethers of alkylene glycols and polyoxyalkylene glycols, etc.)], novolak type epoxy resins (such as phenol novolak type, cresol novolak type epoxy resins, etc.).

[0041] Among the epoxy resins, aromatic epoxy resins (such as bisphenol type epoxy resins, resorcin type epoxy resins, phenol novolak type epoxy resins, etc.) and cycloaliphatic epoxy resins are preferred. Among them, glycidyl ether type aromatic epoxy resins, for example, bisphenol type epoxy resins, phenol novolak type epoxy resins, etc. are preferred.

[0042] 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.

[0043] 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.

[0044] In this embodiment, from the viewpoint of improving the mechanical strength of the molded article, 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.

[0045] The sizing agent preferably contains 0.1 to 3.0 parts by mass, more preferably 0.3 to 2.5 parts by mass, based on 100 parts by mass of the glass fiber (B). By having the content of the sizing agent be 0.1 to 3.0 parts by mass, improvement in hydrolysis resistance and heat shock resistance can be achieved.

[0046] In addition, the sizing agent may contain, in addition to the above components, components such as urethane resin, silane coupling agent, lubricant, nonionic surfactant, antistatic agent, etc., and the blending ratio of each component may be determined as needed. The urethane resin contributes to the binding property and dispersibility of the glass fiber and is obtained from polyisocyanate and polyol, etc. As the silane coupling agent, aminosilane, epoxysilane, chlorosilane, mercaptosilane, vinylsilane, acrylsilane, etc. can be used. As the lubricant, fatty acid amide, quaternary ammonium salt, etc. can be used. Also, as the nonionic surfactant, synthetic alcohol type, natural alcohol type, fatty acid ester type, etc. can be used.

[0047] In the PBT resin composition of this embodiment, the glass fiber (B) preferably contains 10 to 100 parts by mass, more preferably 20 to 80 parts by mass, based on 100 parts by mass of the PBT resin (A).

[0048] [Elastomer (C)] The elastomer (C) used in this embodiment is added to improve the heat shock resistance required when a molded article made of a PBT resin composition is used in an environment where heating and cooling are repeated.

[0049] By imparting toughness to the PBT resin composition, the elastomer (C) can absorb the strain generated in the molded article, and not only the shrinkage rate and / or the linear expansion coefficient during molding or heat treatment are small, but also a resin having good compatibility with the PBT resin (A) can be preferably used. Examples of such an elastomer (C) include olefin-based elastomers, diene-based elastomers, core-shell elastomers, styrene-based elastomers, silicone-based elastomers, and combinations thereof. Among them, olefin-based elastomers and core-shell elastomers are preferable because excellent heat shock resistance can be obtained. In addition, in order to improve the affinity between these elastomers (C) and the PBT resin (A), a known compatibilizer may be used in combination.

[0050] Examples of olefin-based elastomers include copolymers containing at least one unit selected from 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, EP copolymers, and EPD copolymers, and copolymers of olefins and (meth)acrylic monomers (ethylene-ethyl acrylate copolymers, ethylene-glycidyl methacrylate copolymers, etc.). Preferred olefin-based elastomers include EP copolymers, EPD copolymers, and copolymers of olefins and (meth)acrylic monomers, and ethylene ethyl acrylate is particularly preferred. These olefin-based elastomers can be used alone or in combination of two or more.

[0051] The core-shell type 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. As the rubber component of the core layer, an acrylic rubber or the like is used. The rubber component used for the core layer preferably has a glass transition temperature (Tg) of less than 0°C (for example, -10°C or lower), more preferably -20°C or lower (for example, -180°C or higher and -25°C or lower), and particularly preferably -30°C or lower (for example, -150°C or higher and -40°C or lower).

[0052] When using an acrylic rubber as the rubber component, a polymer obtained by polymerizing an acrylic monomer such as an alkyl acrylate as a main component is preferable. As the alkyl acrylate used as the monomer of the acrylic rubber, a C1-C12 alkyl ester of acrylic acid such as butyl acrylate is preferable, and a C2-C6 alkyl ester of acrylic acid is more preferable.

[0053] The acrylic rubber may be a homopolymer or a copolymer of an acrylic monomer. When the acrylic rubber is a copolymer of acrylic monomers, 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, the acrylic rubber may be a copolymer obtained by copolymerizing a crosslinkable monomer.

[0054] In the shell layer, a vinyl-based polymer is preferably used. The vinyl-based polymer is obtained, for example, by polymerizing or copolymerizing at least one monomer selected from aromatic vinyl monomers, vinyl cyanide monomers, methacrylic acid ester monomers, and acrylic acid ester monomers. The core layer and the shell layer of such a core-shell elastomer may be bonded by graft copolymerization. This graft copolymerization can be obtained, if necessary, by adding a graft crosslinking agent that reacts with the shell layer during the polymerization of the core layer to give a reactive group to the core layer and then forming the shell layer. When using a silicone rubber as the graft crosslinking agent, an organosiloxane having a vinyl bond or an organosiloxane having a thiol is used, and preferably, an acryloxy siloxane, a methacryloxy siloxane, or a vinyl siloxane is used.

[0055] [Epoxidized natural oil (D)] In this embodiment, the molecular weight of the natural oil (unsaturated fatty acid ester), which is the raw material of the epoxidized natural oil (D), is preferably about 500 to 1500, more preferably about 600 to 1100. For example, linseed oil or soybean oil is a mixture of fatty acid triglycerides, and in that case, a large amount of C18-carboxylic acid component is present.

[0056] Examples of the natural oil include esters of saturated or unsaturated aliphatic carboxylic acids having 10 to 40 carbon atoms, preferably 16 to 22 carbon atoms, and aliphatic saturated alcohols having 2 to 40 carbon atoms, preferably 2 to 6 carbon atoms.

[0057] An epoxidized natural oil can be produced by reacting these natural oils with an epoxidizing agent, such as a peracid like peracetic acid, to introduce an epoxy group.

[0058] In this embodiment, as the epoxidized natural oil (D), compounds are those obtained by epoxidizing unsaturated bonds of unsaturated fatty acid esters such as olive oil, almond oil, peanut oil, coconut oil, camellia oil, corn oil, cottonseed oil, sesame oil, mustard oil, rapeseed oil, linseed oil, soybean oil, tung oil, mustard oil, perilla oil, walnut oil, sesame oil, safflower oil, sunflower oil, cod liver oil, sardine oil, herring oil, beef tallow, mutton fat, and butter. Specific examples of the epoxidized natural oil (D) include epoxidized sesame oil, epoxidized mustard oil, epoxidized rapeseed oil, epoxidized linseed oil, epoxidized soybean oil, epoxidized tung oil, epoxidized mustard oil, epoxidized perilla oil, epoxidized walnut oil, epoxidized sesame oil, epoxidized cod liver oil, epoxidized sardine oil, and epoxidized herring oil.

[0059] The epoxidized natural oil in this embodiment is preferably an epoxidized natural oil having an epoxy equivalent of 100 to 400 g / eq, preferably 125 to 375 g / eq, more preferably 150 to 250 g / eq, in accordance with DIN EN ISO 3001 (1999-11). Also, a compound epoxidized such that its epoxy group is not bonded at the terminal (i.e., an epoxy group present “inside” the hydrocarbon chain) is preferred.

[0060] The content of the epoxy group is preferably 1 to 20% by mass, more preferably 4 to 15% by mass, still more preferably 6 to 12% by mass, based on the natural oil. The higher the content of the epoxy group (1% by mass or more), the higher the effect on hydrolysis resistance. When the content of the epoxy group is low (20% by mass or less), the thickening of the PBT resin composition is low and the fluidity during injection molding is good.

[0061] Among these epoxidized natural oils (D), epoxidized linseed oil and epoxidized soybean oil are preferred because they can achieve a high level of both availability and high hydrolysis resistance and heat shock resistance.

[0062] The epoxidized natural oil (D) can be used alone or in combination of two or more. Particularly preferred epoxidized natural oils (D) are Adekaizer (registered trademark) O-130P, Adekaizer (registered trademark) O-180A from ADEKA CORPORATION, New Saizer (registered trademark) 510R from NOF CORPORATION, Sansoizer E-9000H, Sansoizer E-2000H from Shin Nippon Rika Co., Ltd., which are available under the following product names.

[0063] The compounding amount of the epoxidized natural oil (D) is 2.0 to 8.0 parts by mass with respect to 100 parts by mass of the PBT resin (A). When the compounding amount of the epoxidized natural oil (D) is less than 2.0 parts by mass, the hydrolysis resistance decreases. The compounding amount is preferably 3.0 parts by mass or more, more preferably 3.5 parts by mass or more. On the other hand, when the compounding amount of the epoxidized natural oil (D) exceeds 8.0 parts by mass, unreacted epoxidized natural oil oozes out and the molded product is contaminated. The compounding amount is preferably 7.0 parts by mass or less, more preferably 6.0 parts by mass or less.

[0064] [Other components] 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 fiber (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 aids, organic fillers, colorants, etc.

[0065] <Method for producing polybutylene terephthalate resin composition> The method for producing the PBT resin composition of the present embodiment is not particularly limited, and generally, equipment and methods known as preparation methods for resin compositions can be used. For example, the necessary components can be mixed and kneaded using a single-screw or twin-screw extruder or other melt-kneading apparatus to prepare molding pellets.

[0066] <Insert molded product> The insert molded article of the present embodiment has the PBT resin composition and the insert member of the present embodiment described above. Therefore, similar to the PBT resin composition of the present embodiment, it has the effect that the hydrolysis resistance and heat shock resistance are significantly improved compared with the prior art.

[0067] The insert molded article of the present embodiment is a composite molded article obtained by previously mounting an insert member such as metal in a molding die and filling the outside thereof with the above PBT resin composition. As a molding method for filling the resin into the die, an injection molding method is generally used. In addition, since the insert member inserted into the PBT resin composition is used for the purpose of taking advantage of its characteristics and compensating for the disadvantages of the resin, when it comes into contact with the PBT resin composition during molding, those that do not change shape or melt are used. For this reason, those mainly formed into rods, pins, screws, etc. in advance with metals such as aluminum, magnesium, copper, iron, brass and their alloys, and inorganic solids such as glass and ceramics can be used.

[0068] The method for producing an insert 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 is put into an extruder, melt-kneaded and pelletized, and this pellet and the insert member are put into an injection molding machine equipped with a predetermined die and injection molded to produce the article.

[0069] The insert molded article of the present embodiment can be suitably used as a molded article that is exposed to a high-temperature and high-humidity environment for a long time, such as for automobiles, trains, and the aviation industry. In this insert molded article, even when it is used for a long time in a sufficient high-temperature and high-humidity environment, it is possible to prevent deterioration due to hydrolysis, and since the heat shock resistance is improved, it can be used for in-vehicle engines, motors, and electrical components such as ECUs, housings, and sensors installed around batteries.

Examples

[0070] Hereinafter, the present embodiment will be described in more detail by way of examples, but the present embodiment is not limited to the following examples.

[0071] [Examples 1 to 3, Comparative Examples 1 to 5] In each of the examples and comparative examples, components (A) to (D) and an antioxidant were used in the ratios (parts by mass) shown in Table 2, and a 30 mmφ twin-screw extruder (TEX30C, manufactured by Nippon Steel Works, Ltd.) was used. The temperature of the raw material supply section and the die tip was set at 260°C, and the temperature between them was set at 220 to 260°C. The discharge rate was 15 kg / h, and the screw rotation speed was 130 rpm. The mixture was melt-kneaded and extruded to obtain pellets made of a PBT resin composition. The details of each component shown in Table 2 are as follows.

[0072] (1) Polybutylene terephthalate resin; PBT resin (A): Manufactured by Polyplastics Co., Ltd., polybutylene terephthalate resin, intrinsic viscosity: 0.86 dL / g, carboxylic acid end group content: 12 meq / kg

[0073] (2) Glass fiber (B); · Glass fiber (B-1): E-glass fiber, average fiber diameter 13 μm (sizing agent: 0.5 mass% of phenol novolak resin, copolymer of maleic anhydride, methyl methacrylate, and methyl acrylate (0.2 mass%)) · Glass fiber (B-2): E-glass fiber, average fiber diameter 13 μm (sizing agent: 0.5 mass% of phenol novolak resin) · Glass fiber (B-3): E-glass fiber, average fiber diameter 13 μm (sizing agent: copolymer of maleic anhydride, methyl methacrylate, and methyl acrylate (0.2 mass%))

[0074] On the other hand, the components of the sizing agents used for the surface treatment of glass fibers (B-1) to (B-3) are shown in Table 1. The numerical values in Table 1 are the contents (mass%) of the respective components with respect to the entire glass fiber. The content of the sizing agent with respect to 100 parts by mass of the glass fiber is 0.7 parts by mass in glass fiber (B-1), 0.5 parts by mass in glass fiber (B-2), and 0.2 parts by mass in glass fiber (B-3).

[0075]

Table 1

[0076] (3) Elastomer (C) · Elastomer (C-1): Manufactured by ENEOS NUC Corporation, ethylene ethyl acrylate copolymer NUC-6570 · Elastomer (C-2): Manufactured by Dow Chemical, core-shell elastomer, Paraloid EXL-2314

[0077] (4) Epoxy compound · Epoxidized natural oil (D-1): Manufactured by ADEKA Corporation, Adekaizer O-180A, epoxy equivalent 188 g / eq · Epoxy resin (D-2): Manufactured by Mitsubishi Chemical Corporation, Epicoat 1004, epoxy equivalent 875 - 975 g / eq

[0078] (5) Antioxidant · Manufactured by BASF Japan Ltd., "Irganox1010"

[0079] [Evaluation] Using the pellets obtained in each example and comparative example, the following evaluation tests were carried out.

[0080] (1) Hydrolysis resistance After drying the PBT resin composition pellets of each example and comparative example obtained with the composition in Table 2 at 140 °C for 3 hours, injection molding was carried out at a cylinder temperature of 260 °C and a mold temperature of 80 °C to produce 1A type tensile test pieces conforming to ISO3167. For the obtained test pieces, tensile strength was measured in accordance with ISO527-1,2. The measurement results are shown in Table 2. Next, using a PCT treatment apparatus (high-accelerated life test apparatus), the test pieces were exposed to 121 °C and 100% RH, and the tensile strength after the damp heat test (after 50 hours, 100 hours, 150 hours) was measured, and the strength retention rate before and after the damp heat treatment was calculated. The calculation results are shown in Table 2.

[0081] (2) Heat shock resistance After drying the PBT resin composition pellets of each example and comparative example obtained with the composition of Table 2 at 140 °C for 3 hours, at a resin temperature of 260 °C, a mold temperature of 65 °C, an injection time of 25 seconds, and a cooling time of 10 seconds, using a mold for test piece molding (a mold in which an iron core with a length of 18 mm, a width of 18 mm, and a height of 30 mm is inserted inside a prism with a length of 22 mm, a width of 22 mm, and a height of 51 mm), insert injection molding was performed so that the minimum wall thickness of a part of the resin part was 1 mm, and an insert molded product was manufactured. Regarding the obtained insert molded product, using a thermal shock tester, after heating at 140 °C for 1 hour and 30 minutes, cooling down to -40 °C and cooling for 1 hour and 30 minutes, and then heating up to 140 °C, a heat shock resistance test was carried out with one cycle being the process of heating up to 140 °C, and the number of cycles until cracks appeared in the molded product was measured to evaluate the heat shock resistance. The measurement results of the number of cycles are shown in Table 2.

[0082]

Table 2

[0083] From Table 2, it can be seen that in Examples 1 to 3, good evaluation results were obtained for both hydrolysis resistance and heat shock resistance. On the other hand, Comparative Examples 1 and 2, which differed from Example 2 only in that glass fiber (B-2) surface-treated with a phenolic novolak resin sizing agent and glass fiber (B-3) surface-treated with a sizing agent containing only a copolymer of maleic anhydride, methyl methacrylate, and methyl acrylate were used, were inferior in hydrolysis resistance. Also, Comparative Example 5, in which the addition amount of epoxidized natural oil was less than that in Examples 1 and 2, was inferior in hydrolysis resistance and heat shock resistance. Also, Comparative Example 4, which differed from Example 2 only in that an epoxy resin was used instead of the epoxidized natural oil, was also inferior in hydrolysis resistance and heat shock resistance. Furthermore, Comparative Example 3, which differed from Example 2 in that it did not contain elastomer (C-1), was inferior in heat shock resistance.

Claims

1. Polybutylene terephthalate resin (A), Glass fiber (B) surface-treated with a sizing agent containing a polymer containing a structural unit derived from a carboxylic acid and / or carboxylic anhydride and an epoxy resin, Elastomer (C), Epoxidized natural oil (D), and comprising A polybutylene terephthalate resin composition, wherein the content of the epoxidized natural oil is 2.0 to 8.0 parts by mass with respect to 100 parts by mass of the polybutylene terephthalate resin (A).

2. The polybutylene terephthalate resin composition according to Claim 1, wherein the average fiber diameter of the glass fiber (B) is 3 to 50 μm, and the content of the sizing agent with respect to 100 parts by mass of the glass fiber (B) is 0.1 to 3.0 parts by mass.

3. The polybutylene terephthalate resin composition according to Claim 1 or 2, wherein the epoxidized natural oil (D) is epoxidized linseed oil or epoxidized soybean oil.

4. The polybutylene terephthalate resin composition according to Claim 1 or 2, wherein the elastomer (C) is an olefin-based elastomer or a core-shell-based elastomer.

5. An insert molded article having an insert member made of the polybutylene terephthalate resin composition according to Claim 1 or 2.

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