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 dimensional accuracy 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, 20 to 100 pts.mass of an amorphous resin (B) containing a polystyrene-based resin and / or a polycarbonate-based resin, and 20 to 100 pts.mass of an inorganic filler (C) 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 used in many applications due to its excellent properties such as heat resistance, chemical resistance, electrical properties, mechanical properties, and moldability. For example, in the automotive field, PBT resin is used for connectors, sensors, actuators, ECU housings, and wiper arm parts, and in the electrical and electronic field, PBT resin is used for relays, switches, coil parts, gears, carrier cases, etc. In these fields, dimensional accuracy is required for installing various circuit boards and heat-generating interior components such as motors inside the housing, or for fitting them with other components.In addition, in the automotive field, high durability is also required because the components are used outdoors for long periods of time.

[0003] However, because PBT resin has an ester group in the molecule, its physical properties tend to deteriorate due to hydrolysis in high-temperature, high-humidity environments. Therefore, improvements using epoxy-based resins and the like have been attempted. Patent Document 1 proposes a PBT resin composition containing a dimensional accuracy improver, an epoxy-based resin, and a quaternary ammonium salt to improve the hydrolysis resistance and dimensional accuracy of PBT resin.

[0004] 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 2 and 3). Patent Document 2 discloses 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 3 also discloses that surface-treated glass fibers containing a novolac-type epoxy resin have excellent long-term heat resistance. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2022-070452 [Patent Document 2] Japanese Patent Application Laid-Open No. 2003-201671 [Patent Document 3] Japanese Patent Application Laid-Open No. 2015-129073 Summary of the Invention [Problem to be solved by the invention]

[0006] As mentioned above, there has been a demand for further improvements in the dimensional accuracy and hydrolysis resistance of PBT resin as product lifespans become longer.

[0007] The present invention has been made in consideration of the above-mentioned conventional problems, and an object of the present invention is to provide a polybutylene terephthalate resin composition capable of molding a resin molded article having both excellent dimensional accuracy and hydrolysis resistance, a method for producing the same, and a resin molded article obtained by molding the resin composition. [Means for solving the problem]

[0008] As a result of intensive research conducted by the present inventors to solve the above-mentioned problems, they 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 18 meq / kg or less, a predetermined amorphous resin, 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, dimensional accuracy and hydrolysis resistance can be significantly improved compared to conventional methods, and they have completed the present invention.

[0009] 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, 20 to 100 parts by mass of an amorphous resin (B) containing a polystyrene-based resin and / or a polycarbonate-based resin, and A polybutylene terephthalate resin composition comprising 20 to 100 parts by mass of an inorganic filler (C) 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.

[0010] (2) The polybutylene terephthalate resin composition according to (1) above, further comprising 0.5 to 3.0 parts by mass of an aromatic carbodiimide and / or an epoxy compound as a hydrolysis resistance improver (D) relative to 100 parts by mass of the polybutylene terephthalate resin (A).

[0011] (3) The polybutylene terephthalate resin composition according to (1) or (2), wherein the inorganic filler (C) 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 (C).

[0012] (4) A resin molded article made of the polybutylene terephthalate resin composition according to (1) or (2).

[0013] (5) A method for producing the polybutylene terephthalate resin composition according to (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; A method for producing a polybutylene terephthalate resin composition, comprising: a step of mixing 100 parts by mass of the polybutylene terephthalate resin (A), 20 to 100 parts by mass of an amorphous resin (B), and 20 to 100 parts by mass of an inorganic filler (C) that has been surface-treated with a sizing agent containing a polymer including structural units derived from carboxylic acid and / or carboxylic anhydride and an epoxy resin.

[0014] (6) A method for producing the polybutylene terephthalate resin composition according to (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; A method for producing a polybutylene terephthalate resin composition, comprising: a step of mixing 100 parts by mass of the polybutylene terephthalate resin (A), 20 to 100 parts by mass of an amorphous resin (B), and 20 to 100 parts by mass of an inorganic filler (C) that has been surface-treated with a sizing agent containing a polymer including structural units derived from carboxylic acid and / or carboxylic anhydride and an epoxy resin. [Effects of the Invention]

[0015] According to the present invention, it is possible to provide a polybutylene terephthalate resin composition capable of molding a resin molded article having both excellent dimensional accuracy and hydrolysis resistance, a method for producing the same, and a resin molded article obtained by molding the resin composition. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 2 is a plan view showing a test piece used in measuring flatness in the examples. DETAILED DESCRIPTION OF THE INVENTION

[0017] <Polybutylene terephthalate resin composition> The PBT resin composition of the present embodiment contains 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, 20 to 100 parts by mass of an amorphous resin (B) containing a polystyrene-based resin and / or a polycarbonate-based resin, and 20 to 100 parts by mass of an inorganic filler (C) that has been surface-treated with a sizing agent containing an epoxy resin and a polymer including structural units derived from a carboxylic acid and / or a carboxylic acid anhydride.

[0018] The PBT resin composition of this embodiment has excellent dimensional accuracy due to the inclusion of a predetermined amount of amorphous resin (B). Furthermore, 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 content of 18 meq / kg or less, and by including a polymer containing structural units derived from carboxylic acid and / or carboxylic acid anhydride as a sizing agent for inorganic filler (C), the composition has excellent hydrolysis resistance. Each component of the PBT resin composition of this embodiment will be described below.

[0019] [Polybutylene terephthalate resin (A)] The PBT resin (A) is a resin obtained by polycondensation of a dicarboxylic acid component containing at least terephthalic acid or its ester-forming derivative (such as a C1-6 alkyl ester or acid halide) and a glycol component containing at least an alkylene glycol having 4 carbon atoms (1,4-butanediol) or its ester-forming derivative (such as an acetylated product). The PBT resin (A) is not limited to a homopolybutylene terephthalate resin, but may also be a copolymer containing 60 mol % or more (particularly 75 mol % to 95 mol %) 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 18 meq / kg or less, and more preferably 5 meq / kg or more and 13 meq / kg or less. By using a PBT resin with a terminal carboxyl group amount within this range, the resulting PBT resin composition is less susceptible to strength reduction due to hydrolysis in a humid and hot environment. To ensure adhesion to inorganic fillers 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 will be reduced, resulting in a decrease 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 0.95 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 within this range is used, the resulting PBT resin composition exhibits excellent hydrolysis resistance and moldability. The intrinsic viscosity 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 1.00 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 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 an ethylene oxide 2-mol adduct of bisphenol A and a propylene oxide 3-mol adduct 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 (e.g., ε-caprolactone); and ester-forming derivatives of these comonomer components (e.g., C1-6 alkyl ester derivatives, acid halides, and acetylated products).

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

[0027] As long as the intrinsic viscosity and carboxylic acid end group content of PBT resin (A) are within the specified ranges, recycled PBT resins can be used (material recycling). PBT resins produced by decomposing waste PBT resins (chemical recycling) into monomers such as 1,4-butanediol and terephthalic acid, and then polycondensing the resulting raw materials, can also be used. The manufacturing method for such PBT resins will be described later.

[0028] [Amorphous resin (B)] In the PBT resin composition of this embodiment, by containing an amorphous resin (B) including a polystyrene-based resin and / or a polycarbonate-based resin, it is possible to suppress warping and deformation of a resin molded article obtained from the PBT resin composition, contributing to improving dimensional accuracy. The amorphous resin (B) can be used alone or in combination of two or more.

[0029] (Polystyrene resin) Polystyrene-based resins include polymers and copolymers containing repeating units derived from aromatic vinyl compounds. Examples of aromatic vinyl compounds include styrene, α-alkyl-substituted styrene, and nuclear-alkyl-substituted styrene. Examples of monomers other than aromatic vinyl compounds include acrylonitrile and methyl methacrylate. The polystyrene-based resin may be modified with rubber, and examples of rubber include polybutadiene, styrene-butadiene copolymer, polyisoprene, and ethylene-propylene copolymer. The polystyrene-based resin may also be modified with epoxy. Specific examples of such polystyrene-based resins include polystyrene, rubber-modified polystyrene, ABS resin, MBS resin, AS resin, and ESBS resin, with ABS resin, AS resin, ESBS resin, and mixtures thereof being preferred. The polystyrene resins can be used singly or in combination of two or more.

[0030] (Polycarbonate resin) Polycarbonate resins can be produced by a solvent method, i.e., by reacting a dihydric phenol with a carbonate precursor such as phosgene, or by transesterification of a dihydric phenol with a carbonate precursor such as diphenyl carbonate, in a solvent such as methylene chloride in the presence of a known acid acceptor and molecular weight modifier. Suitable dihydric phenols include bisphenols, with 2,2-bis(4-hydroxyphenyl)propane, i.e., bisphenol A, being particularly preferred. Bisphenol A may also be partially or completely substituted with another dihydric phenol.

[0031] Examples of dihydric phenols other than bisphenol A include compounds such as hydroquinone, 4,4-dihydroxydiphenyl, bis(4-hydroxyphenyl)alkane, bis(4-hydroxyphenyl)cycloalkane, bis(4-hydroxyphenyl)sulfide, bis(4-hydroxyphenyl)sulfone, bis(4-hydroxyphenyl)sulfoxide, and bis(4-hydroxyphenyl)ether, as well as halogenated bisphenols such as bis(3,5-dibromo-4-hydroxyphenyl)propane and bis(3,5-dichloro-4-hydroxyphenyl)propane. These dihydric phenols may be homopolymers or copolymers of two or more dihydric phenols. Furthermore, the polycarbonate resin may be a thermoplastic randomly branched polycarbonate obtained by reacting a polyfunctional aromatic with a dihydric phenol and / or a carbonate precursor. From the viewpoint of hydrolysis resistance, polycarbonates having a high viscosity are preferred, with a melt viscosity at 300°C and 1000 sec-1 of 0.20 kPa·s or more, more preferably 0.25 kPa·s or more, and most preferably 0.30 kPa·s or more. Polycarbonate resins can be used singly or in combination of two or more.

[0032] The amount of amorphous resin (B) blended into the PBT resin composition of this embodiment is 20 to 100 parts by mass, preferably 30 to 80 parts by mass, and more preferably 40 to 70 parts by mass, per 100 parts by mass of PBT resin, from the viewpoint of sufficient dimensional stability and low warpage of the resulting resin molded article. If the blending amount of amorphous resin is less than 20 parts by mass, the resulting resin molded article will not have sufficient dimensional stability and low warpage, and if it exceeds 100 parts by mass, the heat resistance, mold releasability, hydrolysis resistance, and melt heat stability will be poor.

[0033] [Inorganic filler (C)] In the PBT resin composition of this embodiment, the inorganic filler (C) is surface-treated with a sizing agent containing an epoxy resin and a polymer containing structural units derived from a carboxylic acid and / or a carboxylic acid anhydride. By including the inorganic filler (C), the mechanical strength of the resin molded product can be improved, and furthermore, the surface treatment with a predetermined sizing agent provides excellent hydrolysis resistance.

[0034] 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.

[0035] (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 fibrous inorganic fillers include glass fibers and carbon fibers, with glass fibers being preferred due to their 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 in its composition are preferred due to their quality.

[0036] The average fiber diameter of the fibrous inorganic filler 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 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 images of the fibrous filler taken with a CCD camera before being blended into the resin composition and calculating the weighted average. For example, these can be calculated using a dynamic image analysis / particle (state) analyzer PITA-3 manufactured by Seishin Enterprise Co., Ltd.

[0037] The fibrous inorganic filler can be either one having a circular cross section or one having a non-circular cross section. Examples of non-circular cross sections include oval, elliptical, and cocoon shapes. The irregularity 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 irregularity ratio is in the range of 1.5:1 to 6:1, the effects of flattening the cross section, such as dimensional stability and reduced warpage, can be easily achieved, and a decrease in strength due to excessive flatness and susceptibility to cracking can also be easily suppressed.

[0038] (Non-fibrous inorganic filler) The shape of the non-fibrous inorganic filler is not particularly limited, and examples thereof include granular, ellipsoidal, spindle-like, plate-like, scaly, irregular, etc. Specific examples of non-fibrous inorganic fillers 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 fiber, glass balloons, and glass powder; and others, such as magnesium hydroxide, boehmite, spherical silica, ferrite, silicon carbide, silicon nitride, boron nitride, and various metal powders, but are not limited to these. 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.

[0039] The inorganic filler (C) may be used alone or in combination of two or more kinds.

[0040] Furthermore, 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 to 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 likely to be obtained, and when it is 55% by mass or less, better tensile strength is likely to be obtained. The combination of a fibrous inorganic filler and a non-fibrous inorganic filler is not particularly limited, but examples include a combination 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 it is preferable that the combination contains at least glass fiber and mica.

[0041] Next, the polymer and epoxy resin having structural units derived from carboxylic acid and / or carboxylic anhydride contained in the sizing agent used for surface treatment in the inorganic filler (C) will be described below.

[0042] (Polymers Having Structural Units Derived from Carboxylic Acids and / or Carboxylic Acid Anhydrides) In the polymer (hereinafter also referred to simply as "polymer") having structural units derived from a carboxylic acid and / or a carboxylic acid anhydride, 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, and citraconic acid. These may have a substituent. Among these, acrylic acid, methacrylic acid, and maleic acid are preferred. Examples of the carboxylic acid anhydride include anhydrides of unsaturated carboxylic acids 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 acid anhydride is polymerized alone, or may be copolymers in which two or more carboxylic acids or carboxylic acid anhydrides are copolymerized.

[0043] In the present embodiment, the weight-average molecular weight of the 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 inorganic filler is achieved.

[0044] (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), and the like. Examples of epoxy resins include cycloaliphatic epoxy resins (e.g., cycloaliphatic epoxy resins such as cycloaliphatic epoxy resins (e.g., ...

[0045] 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 resorcinol type epoxy resins; aliphatic epoxy resins (glycidyl ethers of alkylene glycols and polyoxyalkylene glycols), and the like], novolac type epoxy resins (phenol novolac type, cresol novolac type epoxy resins, and the like), and the like.

[0046] Among epoxy resins, aromatic epoxy resins (such as bisphenol-type epoxy resins, resorcinol-type epoxy resins, and phenol novolac-type epoxy resins) and cyclic aliphatic epoxy resins are preferred. Of these, glycidyl ether-type aromatic epoxy resins, such as bisphenol-type epoxy resins and phenol novolac-type epoxy resins, are preferred.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] The content of the sizing agent is preferably 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 (C). By containing the sizing agent in an amount of 0.1 to 3.0 parts by mass, hydrolysis resistance can be improved.

[0051] In addition to the above components, the sizing agent may contain other components such as urethane resin, silane coupling agent, lubricant, nonionic surfactant, and antistatic agent, and the blending ratio of each component may be determined as needed. Urethane resin contributes to the bundling and dispersibility of glass fibers and is obtained from polyisocyanate and polyol, etc. Examples of silane coupling agents that can be used include aminosilane, epoxysilane, chlorosilane, mercaptosilane, vinylsilane, and acrylicsilane. Examples of lubricants that can be used include fatty acid amides and quaternary ammonium salts. Examples of nonionic surfactants that can be used include synthetic alcohols, natural alcohols, and fatty acid esters.

[0052] In the PBT resin composition of this embodiment, the inorganic filler (C) is contained in an amount of 20 to 100 parts by mass, preferably 30 to 90 parts by mass, and more preferably 40 to 80 parts by mass, per 100 parts by mass of the PBT resin (A). If the content of the inorganic filler (C) is less than 20 parts by mass, the effect of improving mechanical strength cannot be obtained, whereas if it exceeds 100 parts by mass, toughness decreases, and fracture from welds and a decrease in strength after wet heat treatment become significant.

[0053] [Hydrolysis resistance improver (D)] In the PBT resin composition of this embodiment, in order to further improve the hydrolysis resistance, it is preferable to contain 0.5 to 3.0 parts by mass of an aromatic carbodiimide and / or an epoxy compound as a hydrolysis resistance improver (D).

[0054] (aromatic carbodiimide compounds) An aromatic carbodiimide compound is a compound having an aromatic main chain and a carbodiimide group (-N=C=N-) in the molecule. Among carbodiimide compounds, aromatic carbodiimide compounds are preferred because of their excellent heat resistance and moist heat resistance.

[0055] Examples of aromatic carbodiimide compounds 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-chlorophenylcarbodiimide, 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'-diphenylmethanecarbodiimide), Examples of suitable carbodiimide compounds include poly(1,3-diisopropylphenylenecarbodiimide), poly(1-methyl-3,5-diisopropylphenylenecarbodiimide), poly(1,3,5-triethylphenylenecarbodiimide), and poly(triisopropylphenylenecarbodiimide). Two or more of these compounds may be used in combination.

[0056] 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 gases and odors when the residence time is long during melt-kneading or molding of the thermoplastic resin.

[0057] 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 part by mass or more, hydrolysis resistance can be improved, and when the content is 3.0 parts by mass or less, a decrease in fluidity is suppressed and the generation of gel components or chars during compounding (when producing the resin composition) or molding processing is suppressed.

[0058] [Epoxy compounds] Examples of the epoxy compound in this embodiment include aromatic epoxy compounds such as biphenyl epoxy compounds, bisphenol A epoxy compounds, phenol novolac epoxy compounds, and cresol novolac epoxy compounds. Two or more epoxy compounds may be used in any combination. The epoxy equivalent is preferably 200 to 1500 g / equivalent (g / eq).

[0059] In this embodiment, the epoxy compound is preferably added in an amount of 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, 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 portions and discoloration due to increased viscosity can be suppressed.

[0060] [Other ingredients] The PBT resin composition of the present embodiment may contain other components as needed, including, but not limited to, inorganic fillers other than the inorganic filler (C), antioxidants, weather stabilizers, molecular weight modifiers, ultraviolet absorbers, antistatic agents, dyes, pigments, lubricants, crystallization accelerators, crystal nucleating agents, near-infrared absorbers, flame retardants, flame retardant assistants, organic fillers, and colorants.

[0061] <Resin molded products> The resin molded article of this embodiment is produced by molding the PBT resin composition of this embodiment described above, and therefore, like the PBT resin composition of this embodiment, has the effect of significantly improving hydrolysis resistance and dimensional accuracy compared to conventional products.

[0062] The method for producing a resin molded article using the PBT resin composition of the present embodiment is not particularly limited, and any known method can be used. For example, the PBT resin composition of the present embodiment can be fed into an extruder, melt-kneaded, and pelletized, and the pellets can be fed into an injection molding machine equipped with a predetermined mold and injection-molded to produce a resin molded article.

[0063] The resin molded article of this embodiment can be suitably used as a resin composition for molded articles that are exposed to high-temperature, high-humidity environments for long periods of time, such as in automobiles, trains, and the aviation industry. Molded articles made from this resin composition have excellent dimensional accuracy and can be prevented from deteriorating due to hydrolysis even when used for long periods of time in a sufficiently high-temperature, high-humidity environment, and therefore can be used for actuator cases, sensors, ECUs, housings such as junction boxes, connectors, etc.

[0064] <Method of producing polybutylene terephthalate resin composition> The method for producing the PBT resin composition of this embodiment has two forms, a first form and a second form, and either form is one form for producing the PBT resin composition of this 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 20 to 100 parts by mass of an amorphous resin (B) and 20 to 100 parts by mass of an inorganic filler (C) that has been surface-treated with a sizing agent containing an epoxy resin and a polymer containing structural units derived from a carboxylic acid and / or a carboxylic acid anhydride, relative to 100 parts by mass of the PBT resin (A).

[0065] In addition, the second embodiment includes a step of obtaining a PBT 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, and a step of mixing 20 to 100 parts by mass of an amorphous resin (B) and 20 to 100 parts by mass of an inorganic filler (C) that has been surface-treated with a sizing agent containing an epoxy resin and a polymer containing structural units derived from a carboxylic acid and / or a carboxylic acid anhydride, relative to 100 parts by mass of the PBT resin (A).

[0066] In the first and second embodiments described above, the PBT resin (A) is obtained by chemical recycling and material recycling, respectively, but the production of the PBT resin composition of the present embodiment described above is not limited to the production methods according to the first and second embodiments. That is, there are no limitations on the method for obtaining the PBT resin (A) 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.

[0067] The first and second embodiments differ in the process for obtaining the PBT resin (A). That is, in the first embodiment, the PBT resin (A) is obtained using 1,4-butanediol and / or terephthalic acid obtained by chemical recycling, whereas in the second embodiment, the PBT resin (A) is obtained by material recycling.

[0068] 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.

[0069] In the first form, PBT resin (A) is produced by decomposing 1,4-butanediol, terephthalic acid, etc. from PBT resin waste etc. down to the monomer level (chemical recycling), and then polycondensing the obtained raw materials. 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.

[0070] In the second embodiment, the PBT resin (A) is obtained by material recycling. In other words, recycled PBT resins can be used as long as their intrinsic viscosity and carboxylic acid end group content are within the specified ranges. Recycled PBT resins can be crushed using a crusher such as a single-screw crusher, twin-screw crusher, triple-screw crusher, or cutter mill. The crushed product can also be melt-mixed using a single-screw or twin-screw extruder and granulated to form pellets. A stainless steel filter can be installed on the breaker plate during melt-mixing to remove foreign matter. Because foreign matter can be the starting point for fracture, removing the foreign matter can maintain the mechanical properties and improve the appearance of molded articles made from the PBT resin composition.

[0071] In either 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 18 meq / kg or less.

[0072] In the step of mixing components (A) to (C), the method for mixing the components is not particularly limited, and any known method can be used, such as feeding the components into an extruder, melt-kneading them, and pelletizing them. [Example]

[0073] 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.

[0074] [Examples 1 to 9, Comparative Examples 1 to 8] In each example and comparative example, components (A) to (D) were melt-mixed and extruded in the ratios (parts by mass) shown in Tables 2 and 3 using a 30 mm diameter twin-screw extruder (TEX30C, manufactured by The Japan Steel Works, Ltd.) at a cylinder temperature of 260°C at the raw material feed 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 of a PBT resin composition. Details of each component shown in Tables 2 and 3 are provided below.

[0075] (1) Polybutylene terephthalate resin (A); (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): PBT resin polycondensed from biomass-derived 1,4-butanediol and terephthalic acid with titanium tetrabutoxide as a catalyst. Intrinsic viscosity: 0.86 dL / g. Carboxylic acid end group content: 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 (10 mm wide, 4 mm thick) conforming to ISO 3167 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 obtain PBT resin (intrinsic viscosity: 0.89 dL / g, carboxylic acid end group content: 15 meq / kg). (A-4): PBT resin manufactured by Polyplastics Co., Ltd., intrinsic viscosity: 0.86 dL / g, carboxylic acid end group amount: 20 meq / kg (A-5): PBT resin manufactured by Polyplastics Co., Ltd. Intrinsic viscosity: 0.69 dL / g Carboxylic acid end group amount: 24 meq / kg

[0076] (2) Amorphous resin (B); (B-1): Acrylonitrile styrene resin (manufactured by Techno UMG Co., Ltd., "AP-20") (B-2): Polycarbonate resin (Teijin Ltd., Panlite "L-1225L" melt viscosity: 0.27 Pa·s)

[0077] (4) Inorganic filler (C); (C-1): Glass fiber: E-glass glass fiber, average fiber diameter: 13 μm (sizing agent: phenol novolac resin 0.5% by mass, copolymer of maleic anhydride, methyl methacrylate and methyl acrylate 0.2% by mass) (C-2): Glass fiber: E-glass glass fiber, average fiber diameter: 13 μm (sizing agent: phenol novolac resin 0.5% by mass) (C-3): Glass fiber: 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)

[0078] Meanwhile, the components of the sizing agent used in the surface treatment of the glass fibers (C-1) to (C-3) are shown in Table 1 below. The values ​​in Table 1 indicate the content (mass%) of each component relative to the total amount of each glass fiber. In the glass fiber (C-1), the sizing agent was contained in an amount of 0.7 parts by mass per 100 parts by mass of the glass fiber (C-1).

[0079] [Table 1]

[0080] (4) Hydrolysis resistance improver (D); (D-1): Epoxy compound: Epikote 1004 manufactured by Mitsubishi Chemical Corporation (D-2): Aromatic carbodiimide compound: Stabaxol P-100, an aromatic polycarbodiimide manufactured by LANXESS.

[0081] [evaluation] The pellets obtained in each of the Examples and Comparative Examples were subjected to the following evaluation tests. (1)Flatness PBT resin composition pellets obtained using the compositions shown in Tables 2 and 3 for each of the Examples and Comparative Examples were dried at 140°C for 3 hours and then injection-molded into 120mm x 120mm x 2mm flat plates (see Figure 1) using a side gate at a cylinder temperature of 260°C, a mold temperature of 60°C, and a dwell pressure of 80MPa. After conditioning for at least 24 hours in an air-conditioned room at 23°C and 50% RH, the heights of the nine points shown in Figure 1 were measured using a Mitutoyo image measuring device, and the flatness was calculated from the difference in height between the highest and lowest points. Tables 2 and 3 show the flatness (unit: mm). A flatness of 10mm or less was considered excellent.

[0082] (2) Hydrolysis resistance PBT resin composition pellets obtained in each example and comparative example using 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 ISO 3167. The tensile strength of the obtained test specimens was measured in accordance with ISO 527-1 and 2. The measurement results are shown in Tables 2 and 3. Next, using a PCT treatment device (highly accelerated life test device), the test specimens were exposed to 121°C and 100% RH, and the tensile strength was measured after a moist heat test (50 hours and 100 hours), and the strength retention before and after the moist heat treatment was calculated. The calculation results are shown in Tables 2 and 3.

[0083] [Table 2]

[0084] [Table 3]

[0085] It can be seen from Tables 2 and 3 that good evaluation results for flatness and hydrolysis resistance were obtained in Examples 1 to 9. That is, Examples 1 to 9 demonstrated that resin molded articles excellent in both dimensional accuracy and hydrolysis resistance could be molded. On the other hand, Comparative Examples 1 to 3 and 8, which contained no or a small amount of amorphous resin (B), showed large warpage and poor flatness. Comparative Example 4, which differs from Example 3 only in that it used glass fibers (C-2) surface-treated with a sizing agent containing only an epoxy resin, also had poor hydrolysis resistance. Similarly, Comparative Example 5, which differs from Example 3 only in that it used glass fibers (C-3) surface-treated with a sizing agent containing only a copolymer of maleic anhydride, methyl methacrylate, and methyl acrylate, also had poor hydrolysis resistance. Furthermore, Comparative Example 6, which used a PBT resin (A-4) with a high amount of carboxylic acid terminal groups, and Comparative Example 7, which used a PBT resin (A-5) with a low intrinsic viscosity, 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, 20 to 100 parts by mass of an amorphous resin (B) containing a polystyrene-based resin and / or a polycarbonate-based resin, and The composition comprises 20 to 100 parts by mass of an inorganic filler (C) that has been surface-treated with a sizing agent containing an epoxy resin and a polymer containing a structural unit derived from a carboxylic acid and / or a carboxylic acid anhydride, 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, further comprising 0.5 to 3.0 parts by mass of an aromatic carbodiimide and / or an epoxy compound as a hydrolysis resistance improver (D) relative to 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 (C) 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 (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 18 meq / kg or less, using 1,4-butanediol and / or terephthalic acid obtained by chemical recycling; the method includes a step of mixing 20 to 100 parts by mass of an amorphous resin (B) and 20 to 100 parts by mass of an inorganic filler (C) that has been surface-treated with a sizing agent containing an epoxy resin and a polymer containing a structural unit derived from a carboxylic acid and / or a carboxylic acid anhydride, with 100 parts by mass of the polybutylene terephthalate resin (A), 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 20 to 100 parts by mass of an amorphous resin (B) and 20 to 100 parts by mass of an inorganic filler (C) that has been surface-treated with a sizing agent containing an epoxy resin and a polymer containing a structural unit derived from a carboxylic acid and / or a carboxylic acid anhydride, with 100 parts by mass of the polybutylene terephthalate resin (A), 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.

Images