Polybutylene terephthalate resin composition and molded article

Abstract

To provide a polybutylene terephthalate resin composition which is excellent in alkali resistance and hydrolysis resistance, and a molded article.SOLUTION: A polybutylene terephthalate resin composition contains a polybutylene terephthalate resin (A), an epoxy-based resin (B), a quaternary ammonium salt (C), an elastomer (D) containing no epoxy group, silicone oil (E) having dynamic viscosity at 25°C of 3,000-10,000 cst, and an inorganic filler (F), wherein the content of the epoxy-based resin (B) and the content of the elastomer (D) containing no epoxy group are within predetermined ranges, 4 R of a quaternary ammonium cation NR4+ constituting the quaternary ammonium salt (C) are each independently an alkyl group having 1 to 6 carbon atoms, an anion is a bromide ion, and the elastomer (D) containing no epoxy group is an ethylene-ethyl acrylate copolymer and / or a core-shell elastomer.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a polybutylene terephthalate resin composition and a molded article. [Background technology]

[0002] Polybutylene terephthalate (hereinafter referred to as "PBT") resin is a crystalline thermoplastic resin that has excellent mechanical strength, electrical properties, and other characteristics, and is therefore used as an engineering plastic in a wide range of applications, including automobiles and electrical and electronic devices. However, because polybutylene terephthalate resin is a polyester resin, it potentially has issues with hydrolysis resistance. Furthermore, it tends to have low long-term durability in alkaline solutions, limiting its usage environments and applications. For example, some parts may be used in locations where they come into contact with toilet cleaners, bathtub cleaners, bleaches, snow-melting agents, etc. These chemicals contain ingredients such as sodium hydroxide, sodium hypochlorite, sodium percarbonate, or calcium chloride, which exposes resin molded articles to alkaline environments. When resin molded articles are subjected to excessive strain due to screwing, metal press-fitting, caulking, or the like and exposed to such alkaline environments for long periods of time, the effects of both the strain and the alkaline components can cause environmental stress cracking, resulting in cracks in the molded articles, which has been problematic. For example, Patent Document 1 discloses that molded articles with excellent alkali resistance and heat shock resistance can be provided by using a resin composition consisting of a polybutylene terephthalate resin, a silicone-based compound with a kinematic viscosity of 1,000 to 10,000 cst at 25°C, and an olefin-based elastomer.

[0003] The hydrolysis resistance of polybutylene terephthalate resins has been improved in the past, and common methods include adding an epoxy resin or using an additive such as a carbodiimide, etc. For example, Patent Document 2 discloses a polybutylene terephthalate resin composition containing a polybutylene terephthalate resin, an epoxy resin, and a quaternary ammonium salt. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2018 / 047662 [Patent Document 2] International Publication No. 2021 / 125203 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide a polybutylene terephthalate resin composition having excellent alkali resistance and hydrolysis resistance, and a molded article thereof. [Means for solving the problem]

[0006] The present inventors have found that the above-mentioned problems can be solved by a polybutylene terephthalate resin composition containing polybutylene terephthalate resin (A), a predetermined content of epoxy resin (B), a quaternary ammonium salt (C) having a predetermined structure, a predetermined content of elastomer (D) not containing epoxy groups, a silicone oil (E) having a predetermined kinematic viscosity, and an inorganic filler (F), and a molded article produced using the polybutylene terephthalate resin composition, and have completed the present invention.

[0007] That is, the present invention relates to the following (1) to (4). (1) A composition comprising a polybutylene terephthalate resin (A), an epoxy resin (B), a quaternary ammonium salt (C), an elastomer (D) not containing an epoxy group, a silicone oil (E) having a kinematic viscosity at 25°C of 3000 to 10000 cst, and an inorganic filler (F), the content of the epoxy resin (B) is 0.5 parts by mass or more and 5 parts by mass or less per 100 parts by mass of the polybutylene terephthalate resin (A); the content of the epoxy group-free elastomer (D) is 5 parts by mass or more per 100 parts by mass of the polybutylene terephthalate resin (A); Quaternary ammonium cation NR4, which constitutes the quaternary ammonium salt (C) + wherein each of the four R's is independently an alkyl group having 1 to 6 carbon atoms, and the anion is a bromide ion; A polybutylene terephthalate resin composition, wherein the epoxy group-free elastomer (D) is an ethylene ethyl acrylate copolymer and / or a core-shell elastomer. (2) The polybutylene terephthalate resin composition according to (1), wherein the quaternary ammonium salt (C) is tetraethylammonium bromide and / or tetrabutylammonium bromide. (3) The polybutylene terephthalate resin composition according to (1) or (2), wherein the epoxy group-free elastomer (D) is an ethylene-ethyl acrylate copolymer. (4) A molded article comprising the polybutylene terephthalate resin composition according to any one of (1) to (3). [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a polybutylene terephthalate resin composition and a molded article having excellent alkali resistance and hydrolysis resistance. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic plan view showing a test piece used in an alkali resistance test in Examples and Comparative Examples. DETAILED DESCRIPTION OF THE INVENTION

[0010] An embodiment of the present invention will be described in detail below. The present invention is not limited to the following embodiment, and can be implemented by making appropriate modifications within the scope that does not impair the effects of the present invention. Furthermore, in this specification, the expression "X to Y" means "X or more and Y or less."

[0011] [Polybutylene terephthalate resin composition] (Polybutylene terephthalate resin) Polybutylene terephthalate resin (PBT resin) contains at least terephthalic acid or its ester-forming derivative (C 1-6 The polybutylene terephthalate resin is obtained by polycondensation of a dicarboxylic acid component containing an alkylene glycol (such as an alkyl ester or acid halide of alkylene glycol or 1,4-butanediol) having at least 4 carbon atoms or an ester-forming derivative thereof (such as an acetylated product). In one embodiment, the polybutylene terephthalate resin is not limited to a homopolybutylene terephthalate resin, but may also be a copolymer containing 60 mol % or more of butylene terephthalate units.

[0012] The amount of terminal carboxyl groups in the polybutylene terephthalate resin is preferably 30 meq / kg or less, but is not particularly limited as long as it does not impede the object of the present invention, and is more preferably 20 meq / kg or less, and even more preferably 15 meq / kg or less.

[0013] The intrinsic viscosity (IV) of the polybutylene terephthalate resin is not particularly limited as long as it does not impair the objectives of the present invention, but is preferably 0.60 dL / g to 1.2 dL / g, and more preferably 0.65 dL / g to 0.9 dL / g. When a polybutylene terephthalate resin having an intrinsic viscosity within this range is used, the resulting polybutylene terephthalate resin composition exhibits particularly excellent moldability. The intrinsic viscosity can also be adjusted by blending polybutylene terephthalate resins having different intrinsic viscosities. For example, a polybutylene terephthalate resin having an intrinsic viscosity of 0.9 dL / g can be prepared by blending a polybutylene terephthalate resin having an intrinsic viscosity of 1.0 dL / g with a polybutylene terephthalate resin having an intrinsic viscosity of 0.7 dL / g. The intrinsic viscosity of the polybutylene terephthalate resin can be measured, for example, in o-chlorophenol at 35°C.

[0014] In preparing polybutylene terephthalate resin, when an aromatic dicarboxylic acid other than terephthalic acid or an ester-forming derivative thereof is used as a comonomer component, for example, C 3 esters such as isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, and 4,4'-dicarboxydiphenyl ether are used. 8-14 Aromatic dicarboxylic acids; succinic acid, adipic acid, azelaic acid, sebacic acid, etc. 4-16 Alkanedicarboxylic acids such as cyclohexanedicarboxylic acid 5-10 cycloalkanedicarboxylic acids; ester-forming derivatives of these dicarboxylic acid components (C 1-6 These dicarboxylic acid components can be used alone or in combination of two or more kinds.

[0015] Among these dicarboxylic acid components, C 8-12 Aromatic dicarboxylic acids such as adipic acid, azelaic acid, and sebacic acid 6-12 The alkanedicarboxylic acids are more preferred.

[0016] In preparing polybutylene terephthalate resin, when a glycol component other than 1,4-butanediol is used as a comonomer component, for example, C 1,4-butanediol such as ethylene glycol, propylene glycol, trimethylene glycol, 1,3-butylene glycol, hexamethylene glycol, neopentyl glycol, 1,3-octanediol, etc. 2-10 alkylene glycols; 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; C-type bisphenol A compounds such as ethylene oxide 2-mol adduct of bisphenol A and propylene oxide 3-mol adduct of bisphenol A 2-4or ester-forming derivatives of these glycols (acetylated products, etc.). These glycol components can be used alone or in combination of two or more.

[0017] Among these glycol components, C such as ethylene glycol and trimethylene glycol 2-6 More preferred are alkylene glycols such as those listed above, polyoxyalkylene glycols such as diethylene glycol, and / or alicyclic diols such as cyclohexanedimethanol.

[0018] 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; C hydroxycarboxylic acids such as propiolactone, butyrolactone, valerolactone, and caprolactone (ε-caprolactone, etc.); 3-12 Lactones; ester-forming derivatives of these comonomer components (C 1-6 alkyl ester derivatives, acid halides, acetylated derivatives, etc.

[0019] The content of the polybutylene terephthalate resin is preferably 30 to 80 mass % of the total mass of the polybutylene terephthalate resin composition, more preferably 40 to 70 mass %, and even more preferably 50 to 70 mass %.

[0020] (epoxy resin) Examples of epoxy resins include aromatic epoxy resins such as biphenyl epoxy resins, bisphenol A epoxy resins, phenol novolac epoxy resins, and cresol novolac epoxy resins. Two or more types of epoxy resins may be used in any combination. The epoxy equivalent is preferably 150 to 1500 g / equivalent (g / eq).

[0021] The content of the epoxy resin in the polybutylene terephthalate resin composition is 0.5 to 10 parts by mass, preferably 0.5 to 8 parts by mass, more preferably 0.5 to 6 parts by mass, even more preferably 0.5 to 5 parts by mass, and particularly preferably 0.5 to 4 parts by mass, relative to 100 parts by mass of the polybutylene terephthalate resin. The content of the epoxy resin in the polybutylene terephthalate resin composition can be measured by a solvent extraction method (Soxhlet extraction method).

[0022] (Quaternary ammonium salts) The quaternary ammonium cation constituting the quaternary ammonium salt contained in the polybutylene terephthalate resin composition has the molecular formula NR4 + It is a positively charged polyatomic ion with the molecular formula NR4 + The four R's are each independently an alkyl group having 1 to 6 carbon atoms.

[0023] Molecular formula NR4 + The number of carbon atoms in each of the four Rs in the formula NR4 is preferably 2 to 5, more preferably 2 to 4, and particularly preferably 4 (butyl group). + The number of carbon atoms in the four Rs in the formula may be the same or different. + The total number of carbon atoms in the four R's is preferably 24 or less, more preferably 24 or less, even more preferably 20 or less, and particularly preferably 16 or less.

[0024] The anion constituting the quaternary ammonium salt contained in the polybutylene terephthalate resin composition has a single negative charge and is a bromide ion.

[0025] Preferred quaternary ammonium salts contained in the polybutylene terephthalate resin composition include tetraethylammonium bromide, tetrapropylammonium bromide, tetrabutylammonium bromide, tetrapentylammonium bromide, and tetrahexylammonium bromide, and it is preferable to contain at least one selected from these. Particularly preferred quaternary ammonium salts include tetraethylammonium bromide and / or tetrabutylammonium bromide.

[0026] The content of the quaternary ammonium salt contained in the polybutylene terephthalate resin composition is preferably 0.1 to 3.0 parts by mass, more preferably 0.15 to 2.0 parts by mass, and even more preferably 0.2 to 1.0 parts by mass, per 100 parts by mass of the polybutylene terephthalate resin (A). The content of the quaternary ammonium salt in the polybutylene terephthalate resin composition can be measured by dissolving the composition in hexafluoro-2-propanol or the like, followed by reprecipitation and separation using a poor solvent such as acetone.

[0027] (Elastomer) The polybutylene terephthalate resin composition contains an elastomer that does not contain epoxy groups, and the elastomer that does not contain epoxy groups is an ethylene-ethyl acrylate copolymer and / or a core-shell elastomer. By including an elastomer that does not contain epoxy groups and is an ethylene-ethyl acrylate copolymer and / or a core-shell elastomer as the elastomer, alkali resistance and hydrolysis resistance can be improved. The term "epoxy group-free" can be determined by extracting the elastomer component from the elastomer alone or the resin composition using an organic solvent (Soxhlet extraction), and then using an infrared spectrophotometer to confirm the presence or absence of epoxy groups in the separated elastomer.

[0028] (ethylene ethyl acrylate copolymer) Ethylene ethyl acrylate copolymer (hereinafter also referred to as "EEA copolymer") is a copolymer containing ethylene and ethyl acrylate as copolymerization components. The copolymerization type is not particularly limited, and the copolymer may be any of random, block, or graft copolymers. For example, the copolymer may partially have two or more structures selected from the random structure, block structure, and graft structure.

[0029] The ratio of ethylene to ethyl acrylate in the copolymer is not particularly limited, but from the viewpoints of ensuring compatibility with the PBT resin and suppressing blocking during production, the melting point of the EEA copolymer is preferably 85°C or higher, more preferably 88°C or higher, and particularly preferably 90°C or higher.

[0030] From the viewpoint of improving the appearance of articles molded from the EEA copolymer, the EEA copolymer preferably has a melt flow rate of 25 g / 10 min or less at 190° C. under a load of 2.16 kg.

[0031] The inclusion of EEA copolymer can improve the toughness of molded articles. On the other hand, olefin-based elastomers (e.g., elastomers containing only olefins as structural units, such as ethylene-propylene copolymers) tend to be insufficiently compatible with polybutylene terephthalate resins, and the use of olefin-based elastomers can result in the surface of molded articles becoming rough and poor in appearance. The use of a highly viscous EEA copolymer with a melt flow rate of 25 g / 10 min or less at 190°C and a load of 2.16 kg can improve the appearance of molded articles.

[0032] In this embodiment, an EEA copolymer that is substantially free of comonomer components other than ethylene and ethyl acrylate may be used, or an EEA copolymer that contains other comonomer components may be used.

[0033] In the EEA copolymer that is substantially free of comonomer components other than ethylene and ethyl acrylate, the amount of comonomers other than ethylene and ethyl acrylate in the copolymerized monomers is 3% by mass or less, preferably 1% by mass or less, and may be 0% by mass.

[0034] When the EEA copolymer contains a comonomer component other than ethylene and ethyl acrylate, examples of the other comonomer include (meth)acrylic acid esters such as maleic anhydride, butyl acrylate, and methyl methacrylate. Examples of the EEA copolymer containing a comonomer component other than ethylene and ethyl acrylate include a graft copolymer of ethylene ethyl acrylate and butyl acrylate-methyl methacrylate (EEA-g-BAMMA copolymer).

[0035] When the EEA copolymer contains a comonomer component other than ethylene and ethyl acrylate, the mass ratio of the total amount of ethylene and ethyl acrylate to the total amount of the comonomer other than ethylene and ethyl acrylate is, for example, preferably 95:5 to 50:50, more preferably 85:15 to 55:45, and even more preferably 80:20 to 60:40.

[0036] The EEA copolymer can be produced by any method. For example, the EEA copolymer can be obtained by mixing predetermined amounts of ethylene and ethyl acrylate (and other comonomer components) and carrying out radical polymerization using a radical initiator in a conventional manner. Alternatively, for example, a grafted precursor obtained by copolymerizing a monomer of a butyl acrylate-methyl methacrylate copolymer component with a radical (co)polymerizable organic peroxide in EEA copolymer particles composed of ethylene and ethyl acrylate can be melt-kneaded to produce a graft copolymer of ethylene ethyl acrylate and butyl acrylate-methyl methacrylate (EEA-g-BAMMA copolymer) through a grafting reaction between the polymers. The EEA copolymer may be used alone or in combination of two or more.

[0037] (core-shell elastomer) A core-shell elastomer is a polymer in which the core layer is made of a rubber component (soft component) and the shell layer is made of a hard component. The rubber component of the core layer is preferably an acrylic rubber from the viewpoint of heat resistance. The acrylic rubber used in the core layer preferably has a glass transition temperature (Tg) of less than 0°C (e.g., -10°C or less), more preferably -20°C or less (e.g., -180°C or more to -25°C or less), and particularly preferably -30°C or less (e.g., -150°C or more to -40°C or less).

[0038] The acrylic rubber used as the rubber component is preferably a polymer obtained by polymerizing an acrylic monomer such as alkyl acrylate as the main component. The alkyl acrylate used as the monomer for the acrylic rubber is a C1-C alkyl acrylate of acrylic acid such as butyl acrylate. 12 Alkyl esters of acrylic acid having a carbon number of 2 to 6 are preferred, and C2 to C6 alkyl esters of acrylic acid are more preferred.

[0039] 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 copolymerized with a crosslinkable monomer.

[0040] Vinyl polymers are preferably used for the shell layer. The vinyl polymers are obtained by polymerizing or copolymerizing at least one monomer selected from, for example, aromatic vinyl monomers, vinyl cyanide monomers, methacrylic acid ester monomers, and acrylic acid ester monomers. The core and shell layers of the core-shell elastomers using acrylic rubber may be bonded by graft copolymerization. This graft copolymerization can be achieved by adding a grafting agent that reacts with the shell layer during polymerization of the core layer, if necessary, to provide reactive groups to the core layer, followed by the formation of the shell layer. When a silicone rubber is used as the grafting agent, an organosiloxane having a vinyl bond or an organosiloxane having a thiol group is used, preferably acryloxysiloxane, methacryloxysiloxane, or vinylsiloxane.

[0041] In one embodiment, the elastomer (D) may be an ethylene ethyl acrylate copolymer. In another embodiment, the elastomer (D) may be a core-shell elastomer.

[0042] The content of the elastomer (D) is 5 parts by mass or more, preferably 5 to 30 parts by mass, more preferably 10 to 30 parts by mass, and even more preferably 15 to 25 parts by mass, per 100 parts by mass of the polybutylene terephthalate resin (A).

[0043] The content of the elastomer is preferably 10% by mass or more, more preferably 15% by mass or more, and even more preferably 17% by mass or more, of the total mass of the polybutylene terephthalate resin composition. The content of the elastomer in the polybutylene terephthalate resin composition can be measured by a solvent extraction method (Soxhlet extraction method).

[0044] (silicone oil) The polybutylene terephthalate resin composition of the present embodiment has high alkali resistance due to the inclusion of the silicone oil (E) having a predetermined kinematic viscosity.

[0045] Preferred examples of silicone oils include pure silicone resins such as dimethylpolysiloxane, methylphenylpolysiloxane, and diphenylpolysiloxane, and modified silicones obtained by reacting pure silicone resins with modifying resins such as alkyd resins, polyester resins, acrylic resins, and epoxy resins, but are not limited to these.

[0046] Also, a cured silicone powder having silicone oil absorbed therein can be used. The silicone oil-absorbed cured silicone powder used here is obtained by blending 0.5 to 80% by weight of silicone oil into finely powdered cured silicone, allowing it to absorb the oil, and then powdering it using any method. As the silicone that absorbs silicone oil to form a hardened silicone powder, for example, conventionally known silicone rubber or silicone gel can be used.

[0047] Examples of silicone oils include those represented by the following general formula (1): R3SiO[R2SiO] n SiR3(1) (wherein each R is independently a substituted or unsubstituted monovalent hydrocarbon group or a hydroxyl group, and n is an integer). In the above formula, each R is independently a substituted or unsubstituted monovalent hydrocarbon group or a hydroxyl group. Examples of the substituted or unsubstituted monovalent hydrocarbon group include alkyl groups such as methyl, ethyl, and propyl; alkenyl groups such as vinyl and allyl; aralkyl groups such as cycloalkyl and β-phenylethyl; 3,3,3-trifluoropropyl, 3-mercaptopropyl, 3-aminopropyl, and 3-glycidoxypropyl.

[0048] The silicone oil (E) according to the present embodiment has a kinematic viscosity at 25°C of 3,000 to 10,000 cSt (10 to 100 cm 2 / s), preferably in the range of 3500 to 6000 cSt, and particularly preferably 4000 to 5500 cSt. If the kinematic viscosity is low, bleeding will occur, reducing the durability of the alkali resistance. On the other hand, if the kinematic viscosity is high, bleeding will be difficult, reducing the alkali resistance effect. The kinematic viscosity can be measured using a rotational viscometer (ISO 3219). One type of silicone oil may be used alone, or two or more types may be used in combination.

[0049] From the viewpoint of the effect of improving the alkali resistance of the molded article, the content of the silicone oil (E) is preferably 0.5 parts by mass or more, more preferably 0.6 parts by mass or more, and even more preferably 0.7 parts by mass or more, per 100 parts by mass of the polybutylene terephthalate resin (A). On the other hand, from the viewpoint of suppressing problems caused by seepage from the molded article (such as contact contamination), the content of the silicone oil (E) is preferably 2 parts by mass or less, more preferably 1.5 parts by mass or less, and even more preferably 1.1 parts by mass or less, per 100 parts by mass of the polybutylene terephthalate resin (A). The content of silicone oil in the polybutylene terephthalate resin composition can be measured by measuring with an infrared spectrophotometer using a calibration curve, or by extracting it by a solvent extraction method (Soxhlet extraction method) using an organic solvent such as chloroform, evaporating the solvent to dryness, and then performing NMR analysis.

[0050] (inorganic filler) Examples of the inorganic filler (F) include fibrous fillers, plate-like fillers, and powder-like fillers. The inclusion of an inorganic filler can improve mechanical properties and heat resistance, such as deflection temperature under load. Examples of fibrous fillers include inorganic fibers such as glass fibers, asbestos fibers, carbon fibers, silica fibers, alumina fibers, silica-alumina fibers, aluminum silicate fibers, zirconia fibers, potassium titanate fibers, silicon carbide fibers, and whiskers (such as whiskers of silicon carbide, alumina, and silicon nitride). Examples of plate-like fillers include talc, mica, glass flakes, and graphite. Examples of powder-like fillers include glass beads, glass powder, milled fibers (such as milled glass fibers), and wollastonite.

[0051] The average diameter of the fibrous filler may be, for example, about 1 μm to 30 μm (preferably 5 μm to 20 μm, more preferably 10 to 15 μm), and the average length may be, for example, about 100 μm to 5 mm (preferably 300 μm to 4 mm, more preferably 500 μm to 3.5 mm). The average primary particle diameter of the plate-like or granular filler may be, for example, about 0.1 μm to 500 μm, preferably about 1 μm to 100 μm. These inorganic fillers may be used alone or in combination of two or more. The average diameter and average length of the fibrous filler, as well as the average primary particle diameter of the plate-like or granular filler, are values ​​calculated by analyzing images taken with a CCD camera of the fibrous filler, plate-like or granular filler before being blended into the polybutylene terephthalate resin composition, and then calculating the weighted average. These values ​​can be calculated using, for example, a dynamic image analysis / particle (state) analyzer PITA-3 manufactured by Seishin Enterprise Co., Ltd. The aspect ratio of the plate-like or powdery filler is not particularly limited, and can be, for example, 1 or more and 10 or less.

[0052] (Other ingredients) To impart desired properties according to the purpose to the polybutylene terephthalate resin composition, known substances generally added to thermoplastic resins and thermosetting resins, for example, stabilizers such as antioxidants and ultraviolet absorbers, antistatic agents, colorants such as dyes and pigments, mold release agents, lubricants, crystallization accelerators, crystal nucleating agents, etc., can be blended within a range that does not impair the effects of the present invention.

[0053] The method for producing the polybutylene terephthalate resin composition is not limited, and examples thereof include a method in which each component is melt-kneaded and extruded into pellets using a melt-kneading device such as a single-screw or twin-screw extruder, and a method in which pellets (master batches) with different compositions are prepared and then a predetermined amount of the pellets are mixed.

[0054] (molded product) The molded article of this embodiment is obtained by molding the polybutylene terephthalate resin composition described above. That is, the molded article contains the polybutylene terephthalate resin composition described above. The molding method is not particularly limited, and known molding methods can be used. For example, (1) the components are mixed, kneaded and extruded using a single- or twin-screw extruder to prepare pellets, and then molded; (2) pellets (master batches) with different compositions are first prepared, and a predetermined amount of the pellets is mixed (diluted) and molded to obtain a molded article of the desired composition; or (3) one or more of the components are directly charged into a molding machine. The pellets may be prepared, for example, by melt-mixing components other than a brittle component (such as a glass-based reinforcing material) and then mixing the brittle component. The molding method for other molded articles made of thermoplastic resins is also not particularly limited, and known molding methods can be used.

[0055] The molded article may be produced by melt-kneading the polybutylene terephthalate resin composition and molding it by a conventional method such as extrusion molding, injection molding, compression molding, blow molding, vacuum molding, rotational molding, gas injection molding, etc. The mold temperature during injection molding is usually about 40 to 90°C, preferably about 50 to 80°C, and more preferably about 60 to 80°C.

[0056] The molded article may contain a colorant. Examples of the colorant include inorganic pigments (black pigments such as carbon black (e.g., acetylene black, lamp black, thermal black, furnace black, channel black, ketjen black, etc.), red pigments such as iron oxide red, orange pigments such as molybdate orange, and white pigments such as titanium oxide), and organic pigments (yellow pigments, orange pigments, red pigments, blue pigments, green pigments, etc.). The average particle size of the carbon black may be typically 10 to 1,000 nm, preferably about 10 to 100 nm. The proportion of the colorant is 0.1 to 10 wt % of the total molded article, preferably about 0.3 to 5 wt % (e.g., 0.3 to 3 wt %).

[0057] [Example] The present invention will be specifically explained below with reference to examples, but the present invention is not limited to the following examples as long as it does not depart from the gist of the invention.

[0058] <Material> (A) Polybutylene terephthalate resin (PBT) PBT: Polybutylene terephthalate resin manufactured by Polyplastics Co., Ltd., with a terminal carboxyl group content of 12 meq / kg and an intrinsic viscosity of 0.87 dL / g (B) Epoxy resin Epoxy resin: Mitsubishi Chemical Corporation, Epicoat JER1004K (epoxy equivalent: 925g / eq) (C) Quaternary ammonium salts or their substitutes (C-1) Tetraethylammonium bromide (C-2) Tetrapropylammonium bromide (C-3) Tetrabutylammonium bromide (C-4) Tetrapentylammonium bromide (C-5) Tetrahexylammonium bromide (C-6) Tetraheptylammonium bromide (C-7) Tetrabutylammonium iodide (C-8) Benzyltrimethylammonium bromide (C-9) Cetyldimethylethylammonium bromide (C-10) Dodecyltrimethylammonium bromide (C-11) Phenylboronic Acid (C-12) Calcium Stearate (D) Elastomer (D-1) Ethylene ethyl acrylate resin ZE749, manufactured by Ube Maruzen Polyethylene Co., Ltd. (D-2) Acrylic core-shell polymer Paraloid EXL2311, manufactured by Dow Chemical Company (D-3) Ethylene-glycidyl methacrylate copolymer Bondfast 7L, manufactured by Sumitomo Chemical Co., Ltd. (D-4) Epoxy-containing acrylic core-shell polymer Paraloid EXL2314, manufactured by Dow Chemical Company (D-5) Polyester elastomer Pelprene P90BD, manufactured by Toyobo Co., Ltd. (E) Silicone oil (E-1) Silicone oil: Dimethylpolysiloxane with a kinematic viscosity of 5000 cSt at 25°C (E-2) Silicone oil: Dimethylpolysiloxane with a kinematic viscosity of 300 cSt at 25°C (E-3) Silicone oil: Dimethylpolysiloxane with a kinematic viscosity of 1000 cSt at 25°C (E-4) Silicone oil: Dimethylpolysiloxane with a kinematic viscosity of 50,000 cSt at 25°C (F) Nippon Electric Glass, circular cross-section glass fiber ECS03T-127 (average fiber diameter 13 μm, average fiber length 3 mm)

[0059] <Evaluation method> (Examples 1 to 6, Comparative Examples 1 to 19) The components were mixed in the proportions shown in Tables 1 and 2, and then melt-kneaded and extruded using a TEX-30 extruder manufactured by Japan Steel Works, Ltd., at a cylinder temperature of 260°C, a discharge rate of 15 kg / h, and a screw rotation speed of 130 rpm to obtain pellets of a polybutylene terephthalate resin composition. The obtained pellets were evaluated for the following properties.

[0060] (Hydrolysis resistance) The obtained pellets of polybutylene terephthalate resin composition were dried at 140°C for 3 hours, and then injection molded at a cylinder temperature of 260°C and a mold temperature of 80°C to prepare 1A type tensile test specimens in accordance with ISO3167.The tensile strength of the obtained test specimens was measured in accordance with ISO527-1,2.

[0061] Next, another tensile test piece prepared in the same manner was subjected to a pressure cooker test under the conditions described below, and then the tensile strength was measured in accordance with ISO 527-1, 2. The strength retention (%) was calculated from the ratio to the tensile strength of the untreated piece. The pressure cooker test was performed under conditions of 121°C, 100% Rh, and 203 kPa for 75 hours (75 hr) or 100 hours (100 hr). Test pieces with a strength retention of 80% or more after 100 hours of pressure cooker test were judged to have excellent hydrolysis resistance.

[0062] (3) Alkali resistance The resulting pellets of polybutylene terephthalate resin composition were dried at 140°C for 3 hours and then injection molded at a cylinder temperature of 250°C and a mold temperature of 70°C to produce a molded piece 10 in the shape of a 1 mm thick, 80 mm x 80 mm flat plate with a weld, as shown in Figure 1. The circle in Figure 1 indicates a through hole 2. The resin flow that flows into the mold from film gate 1 splits into upper and lower parts as shown in Figure 1 along the cylindrical wall surface inside the mold to form through hole 2, before rejoining and filling the cavity. The joined part is weld 3. Next, the molded specimen was cut into a 10 mm wide, 80 mm long strip with a weld located approximately in the center of the longitudinal direction to prepare a test specimen. The test specimen was fixed in a bent state to a jig so that a constant 1.0% bending strain was applied to the weld. In this state, the jig and the test specimen were immersed in a 10% by mass aqueous solution of sodium hydroxide and allowed to stand at an ambient temperature of 23°C. The test specimens were observed for cracks at specific intervals. Evaluations were performed using three test specimens for each pellet of each Example and Comparative Example, and the time until cracks occurred in at least one of the three test specimens was determined. Tables 1 and 2 show the evaluation results 50 and 100 hours after the start of immersion. A indicates that no cracks occurred in any of the three test specimens, and B indicates that cracks occurred in at least one of the three test specimens. The results are shown in Tables 1 and 2.

[0063] [Table 1]

[0064] [Table 2]

[0065] As shown in Tables 1 and 2, each Example exhibited high tensile strength retention even after PCT treatment. In particular, each Example demonstrated significant superiority 100 hours after PCT treatment. Furthermore, no cracks were observed after immersion in sodium hydroxide solution for 100 hours, demonstrating good alkali resistance. In other words, the polybutylene terephthalate resin compositions of the Examples exhibited excellent alkali resistance and hydrolysis resistance. In particular, they were able to maintain excellent alkali resistance and hydrolysis resistance even after treatment for a long period of time exceeding 100 hours.

[0066] On the other hand, Comparative Examples 2, 4 to 8 in Tables 1 and 2 show that the effect is not obtained unless the four Rs constituting the cation of the quaternary ammonium salt are alkyl groups having 1 to 6 carbon atoms, and that if they are functional groups having 7 or more carbon atoms, sufficient effect on hydrolysis resistance is not obtained. Comparative Example 3 shows that the effect cannot be obtained unless the anion of the quaternary ammonium salt is a bromide ion, and that a sufficient effect on hydrolysis resistance cannot be obtained with other halide ions (iodide ions). Comparative Example 9 shows that when no epoxy resin is included, a sufficient effect on hydrolysis resistance cannot be obtained. Comparative Examples 10 and 13 show that when a quaternary ammonium bromide salt and a silicone oil having a predetermined kinematic viscosity are not included, the effects of both alkali resistance and hydrolysis resistance are not sufficiently obtained. Comparative Example 11 shows that when a silicone oil having a predetermined kinematic viscosity is not included, a sufficient effect is not obtained even in an alkali resistance test of about 50 hours. Comparative Examples 12 and 14 show that if the kinematic viscosity of the silicone oil is too high or too low, sufficient alkali resistance cannot be obtained.

[0067] Comparative Examples 15 to 19 in Table 2 show that alkali resistance is not achieved when the amount of elastomer added is small, and furthermore, sufficient alkali resistance is not achieved with elastomers other than ethylene-ethyl acrylate copolymers or core-shell elastomers that do not contain epoxy groups.

[0068] The above results indicate that in a polybutylene terephthalate resin composition containing a polybutylene terephthalate resin and an epoxy resin, in order to improve both the alkali resistance and hydrolysis resistance and to maintain these effects for a long period of time, it is essential to combine an elastomer with a specific structure, a silicone oil with a specific kinematic viscosity, and a quaternary ammonium salt with a specific structure.

Claims

1. Polybutylene terephthalate resin (A), an epoxy resin (B); a quaternary ammonium salt (C); an elastomer (D) containing no epoxy groups; A silicone oil (E) having a kinematic viscosity at 25°C of 3500 to 6000 cst; an inorganic filler (F); Contains the content of the epoxy resin (B) is 0.5 parts by mass or more and 5 parts by mass or less per 100 parts by mass of the polybutylene terephthalate resin (A); the content of the epoxy group-free elastomer (D) is 5 parts by mass or more per 100 parts by mass of the polybutylene terephthalate resin (A); the quaternary ammonium salt (C) is tetraethylammonium bromide and / or tetrabutylammonium bromide, the epoxy group-free elastomer (D) is an ethylene ethyl acrylate copolymer and / or a core-shell elastomer; A polybutylene terephthalate resin composition, wherein the content of the silicone oil (E) is 0.5 to 0.9 parts by mass per 100 parts by mass of the polybutylene terephthalate resin (A).

2. 2. The polybutylene terephthalate resin composition according to claim 1, wherein the epoxy group-free elastomer (D) is an ethylene ethyl acrylate copolymer.

3. A molded article comprising the polybutylene terephthalate resin composition according to claim 1 or 2.

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