Polybutylene terephthalate resin composition and molded article

Abstract

To provide a polybutylene terephthalate resin composition that can make a molding having excellent toughness and appearance.SOLUTION: Provided is a polybutylene terephthalate resin composition comprising (A) 100 pts.mass of a polybutylene terephthalate resin having an intrinsic viscosity of 0.65 to 0.90 dl / g, (B) 5 to 30 pts.mass of an ethylene-ethyl acrylate copolymer, and (C) 10 to 100 pts.mass of an inorganic filler, wherein the melt flow rate of the (B) ethylene-ethyl acrylate copolymer at 190°C under a load of 2.16 kg is 25 g / 10 min or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] SUMMARY OF THE INVENTION An embodiment of the present invention relates to a polybutylene terephthalate resin composition and a molded article. [Background technology]

[0002] Polybutylene terephthalate 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.

[0003] When a molded article is obtained using a polybutylene terephthalate resin, a resin composition obtained by mixing the polybutylene terephthalate resin with various additives is generally used. As such additives, for example, olefin-based elastomers are generally used for the purpose of improving the impact resistance and toughness of molded articles.

[0004] Patent Document 1 describes a resin composition containing a thermoplastic resin having an intrinsic viscosity of 0.82 dL / g or less, measured at 30°C in a 1:1 (mass ratio) mixed solvent of tetrachloroethane and phenol, and an impact modifier such as an ethylene-alkyl acrylate copolymer having a melt flow rate (MFR) of 50 g / 10 min or more, measured at 190°C using a test load of 2.16 kg. Patent Document 2 describes that adding a thickener such as a polyolefin resin or elastomer having a melt flow rate (MFR) of 20 g / 10 min or less to a polyester resin improves the drawdown phenomenon during injection molding and also improves the impact resistance of the molded product. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2021-66787 [Patent Document 2] Japanese Patent Application Laid-Open No. 2004-300450 Summary of the Invention [Problem to be solved by the invention]

[0006] Olefin elastomers tend to be insufficiently compatible with polybutylene terephthalate resins, and when olefin elastomers are used, the surface of the molded article may become rough, resulting in poor appearance. Even if a compatibilizer is used to improve compatibility, it tends to be difficult to obtain a sufficient improvement in appearance.

[0007] An object of an embodiment of the present invention is to provide a polybutylene terephthalate resin composition that can be used to mold molded articles that are excellent in toughness, rigidity, and appearance. [Means for solving the problem]

[0008] One embodiment of the present invention relates to a polybutylene terephthalate resin composition comprising: (A) 100 parts by mass of a polybutylene terephthalate resin having an intrinsic viscosity of 0.65 to 0.90 dL / g; (B) 5 to 30 parts by mass of an ethylene-ethyl acrylate copolymer; and (C) 10 to 100 parts by mass of an inorganic filler, wherein the melt flow rate of the (B) ethylene-ethyl acrylate copolymer at 190°C under a load of 2.16 kg is 25 g / 10 min or less. Another embodiment of the present invention relates to a molded article made using the polybutylene terephthalate resin composition. [Effects of the Invention]

[0009] According to an embodiment of the present invention, it is possible to provide a polybutylene terephthalate resin composition capable of forming a molded article having excellent toughness, rigidity, and appearance, and a molded article formed using the resin composition. [Brief explanation of the drawings]

[0010] [Figure 1]FIG. 1 is a schematic diagram showing the upper surface of a molded piece used in the evaluation of appearance, surface roughness, and alkali resistance in the examples. [Figure 2] FIG. 2 shows photographs of reference examples corresponding to the appearance evaluation grades A, B, and C in the examples. DETAILED DESCRIPTION OF THE INVENTION

[0011] Preferred embodiments of the present invention will be described below, but the present invention is not limited to the following embodiments.

[0012] <Polybutylene terephthalate resin composition> A polybutylene terephthalate resin composition (hereinafter sometimes simply referred to as a "resin composition") according to one embodiment of the present invention contains at least a polybutylene terephthalate resin, an ethylene-ethyl acrylate copolymer, and an inorganic filler.

[0013] Each component that can be used in the resin composition of this embodiment will be described below.

[0014] (A) Polybutylene terephthalate resin (A) Polybutylene terephthalate resin (hereinafter also referred to as "PBT resin") contains at least terephthalic acid or its ester-forming derivative (C 1-6 It is a polybutylene terephthalate resin obtained by polycondensation of a dicarboxylic acid component containing an alkylene glycol (1,4-butanediol) having at least 4 carbon atoms or an ester-forming derivative thereof (acetylated product, etc.) and a glycol component containing an alkylene glycol (1,4-butanediol) having at least 4 carbon atoms or an ester-forming derivative thereof (acetylated product, etc.). The (A) polybutylene terephthalate resin is not limited to a homopolybutylene terephthalate resin, but may be a copolymer containing 60 mol % or more (particularly 75 mol % or more and 95 mol % or less) of butylene terephthalate units.

[0015] The intrinsic viscosity (IV) of the (A) polybutylene terephthalate resin is preferably 0.65 dL / g or more and 0.90 dL / g or less, more preferably 0.70 dL / g or more and 0.90 dL / g or less, and even more preferably 0.75 dL / g or more and 0.90 dL / g or less, and may be, for example, 0.85 dL / g or more and 0.90 dL / g or less. When a polybutylene terephthalate resin having an intrinsic viscosity within this range is used, the resulting polybutylene terephthalate resin composition will have particularly excellent appearance and strength. The intrinsic viscosity can also be adjusted by blending polybutylene terephthalate resins with different intrinsic viscosities. For example, a polybutylene terephthalate resin with an intrinsic viscosity of 0.85 dL / g can be prepared by blending a polybutylene terephthalate resin with an intrinsic viscosity of 1.0 dL / g with a polybutylene terephthalate resin with an intrinsic viscosity of 0.7 dL / g. (A) The intrinsic viscosity (IV) of the polybutylene terephthalate resin can be measured, for example, in o-chlorophenol at a temperature of 35°C.

[0016] The amount of terminal carboxyl groups in the (A) polybutylene terephthalate resin is not particularly limited as long as it does not impair the object of the present invention. The amount of terminal carboxyl groups in the polybutylene terephthalate resin (A) is preferably 30 meq / kg or less, more preferably 25 meq / kg or less, while the amount of terminal carboxyl groups in the polybutylene terephthalate resin (A) is preferably 5 meq / kg or more, more preferably 10 meq / kg or more. The amount of terminal carboxyl groups in the (A) polybutylene terephthalate resin is preferably 5 meq / kg or more and 30 meq / kg or less, more preferably 10 meq / kg or more and 25 meq / kg or less. By using a polybutylene terephthalate resin having a terminal carboxyl group amount in this range, the resulting polybutylene terephthalate resin composition is less susceptible to strength reduction due to hydrolysis in a humid and hot environment.

[0017] In the (A) polybutylene terephthalate resin, examples of the dicarboxylic acid component (comonomer component) other than terephthalic acid and its ester-forming derivatives include C 2,4'-dicarboxydiphenyl ether, such as isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, and 4,4'-dicarboxydiphenyl ether. 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.

[0018] 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.

[0019] In the (A) polybutylene terephthalate resin, examples of glycol components (comonomer components) other than 1,4-butanediol include C glycols such as ethylene glycol, propylene glycol, trimethylene glycol, 1,3-butylene glycol, hexamethylene glycol, neopentyl glycol, and 1,3-octanediol. 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 2-4 or ester-forming derivatives of these glycols (acetylated products, etc.). These glycol components can be used alone or in combination of two or more.

[0020] 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 alicyclic diols such as cyclohexanedimethanol.

[0021] 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.

[0022] Any of the polybutylene terephthalate copolymers copolymerized with the comonomer components described above can be suitably used as the polybutylene terephthalate resin (A). Furthermore, a homopolybutylene terephthalate polymer and a polybutylene terephthalate copolymer may be used in combination as the polybutylene terephthalate resin (A).

[0023] (B) 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 it may be any of random, block, or graft copolymers, and may partially have two or more structures selected from the random structure, block structure, and graft structure.

[0024] 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.

[0025] From the viewpoint of improving the appearance of articles molded from the EEA copolymer, the EEA copolymer (B) preferably has a melt flow rate of 25 g / 10 min or less at 190° C. under a load of 2.16 kg.

[0026] The inclusion of EEA copolymer can improve the toughness of molded articles. On the other hand, olefin-based elastomers 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 resulting in poor 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.

[0027] From the viewpoint of improving the appearance of molded articles, the melt flow rate of the (B) EEA copolymer at 190°C under a load of 2.16 kg is preferably 25 g / 10 min or less, more preferably 20 g / 10 min or less, even more preferably 2 g / 10 min or less, and particularly preferably 1 g / 10 min or less. The melt flow rate of the (B) EEA copolymer at 190°C under a load of 2.16 kg may be, for example, 0.01 g / 10 min or more and 25 g / 10 min or less. The melt flow rate can also be adjusted by blending EEA copolymers having different melt flow rates. For example, an EEA copolymer having a melt flow rate of 15 g / 10 min at 190°C and a load of 2.16 kg can be prepared by blending an EEA copolymer having a melt flow rate of 30 g / 10 min at 190°C and a load of 2.16 kg with an EEA copolymer having a melt flow rate of 10 g / 10 min at 190°C and a load of 2.16 kg. The melt flow rate at 190°C and a load of 2.16 kg is a value measured under conditions of 190°C and a load of 2.16 kg by a method conforming to ISO1133.

[0028] 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.

[0029] 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.

[0030] When the (B) EEA copolymer contains a comonomer component other than ethylene and ethyl acrylate, examples of the other comonomer include maleic anhydride, (meth)acrylic acid esters such as butyl acrylate, and methyl methacrylate. For example, a comonomer containing a highly reactive functional group such as a glycidyl group may also be used. Examples of EEA copolymers containing a comonomer component other than ethylene and ethyl acrylate include graft copolymers of ethylene ethyl acrylate and butyl acrylate-methyl methacrylate (EEA-g-BAMMA copolymers).

[0031] When the (B) 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.

[0032] (B) EEA copolymer can be produced by any method. For example, an 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.

[0033] The (B) EEA copolymer may be used alone or in combination of two or more.

[0034] The content of (B) EEA copolymer is preferably 5 parts by mass or more and 30 parts by mass or less, more preferably 10 parts by mass or more and 25 parts by mass or less, and even more preferably 15 parts by mass or more and 20 parts by mass or less, relative to 100 parts by mass of (A) polybutylene terephthalate resin. From the viewpoint of impact resistance, the content of the (B) EEA copolymer is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and even more preferably 15 parts by mass or more, per 100 parts by mass of the (A) polybutylene terephthalate resin. On the other hand, from the viewpoint of rigidity, the content of the (B) EEA copolymer is preferably 30 parts by mass or less, more preferably 25 parts by mass or less, and even more preferably 20 parts by mass or less, per 100 parts by mass of the (A) polybutylene terephthalate resin.

[0035] (C) Inorganic filler The polybutylene terephthalate resin composition may contain (D) an inorganic filler. By containing (D) an inorganic filler, mechanical properties and heat resistance can be improved. From the viewpoint of improving the rigidity of a molded article, the polybutylene terephthalate resin composition preferably contains (D) an inorganic filler. Furthermore, the molding shrinkage rate and linear expansion coefficient of the polybutylene terephthalate resin composition can be reduced.

[0036] Examples of (C) inorganic fillers include fibrous inorganic fillers (e.g., glass fibers, asbestos fibers, silica fibers, alumina fibers, silica-alumina fibers, zirconia fibers, boron nitride fibers, silicon nitride fibers, boron fibers, potassium titanate fibers, silicon carbide fibers, and whiskers (such as alumina and silicon nitride whiskers)), plate-like inorganic fillers (e.g., talc, mica, glass flakes, and graphite), and powder-like inorganic fillers (e.g., glass beads, glass powder, milled fibers (milled fibers such as glass), and wollastonite). Among these inorganic fillers, glass-based fillers (e.g., glass fibers, glass flakes, and glass beads), talc, mica, and wollastonite are preferred, with glass fibers being particularly preferred in terms of availability, strength, and rigidity. Plate-like and powder-like fillers are also preferred in terms of suppressing the anisotropy of the molding shrinkage and linear expansion coefficient of the polybutylene terephthalate resin composition. When using these fillers, known surface treatment agents can be used as needed.

[0037] When a fibrous filler is used as the (C) inorganic filler, its shape is not particularly limited, but for example, the length is about 100 μm to 5 mm, more preferably about 500 μm to 3 mm, and the diameter is about 1 to 50 μm, more preferably about 3 to 30 μm. When a plate-like filler or powdery filler is used, its average particle size is also not particularly limited, but for example, it is about 0.1 to 100 μm, more preferably about 0.1 to 50 μm. These (C) fillers can be used alone or in combination of two or more.

[0038] The content of (C) inorganic filler is preferably 10 parts by mass or more and 100 parts by mass or less, more preferably 20 parts by mass or more and 90 parts by mass or less, even more preferably 30 parts by mass or more and 75 parts by mass or less, and even more preferably 40 parts by mass or more and 60 parts by mass or less, relative to 100 parts by mass of the polybutylene terephthalate resin composition.

[0039] From the viewpoint of rigidity, the content of (C) inorganic filler is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, even more preferably 30 parts by mass or more, and even more preferably 40 parts by mass or more, relative to 100 parts by mass of the polybutylene terephthalate resin composition. On the other hand, from the viewpoint of flowability, the content of (C) inorganic filler is preferably 100 parts by mass or less, more preferably 90 parts by mass or less, even more preferably 75 parts by mass or less, and even more preferably 60 parts by mass or less, relative to 100 parts by mass of the polybutylene terephthalate resin composition.

[0040] (D) Silicone compounds The polybutylene terephthalate resin composition of the present embodiment preferably contains (D) a silicone-based compound.

[0041] Preferred examples of silicone compounds include pure silicone resins such as dimethylpolysiloxane, methylphenylpolysiloxane, and diphenylpolysiloxane, which are generally known as silicone oils, and modified silicones obtained by reacting pure silicone resins with modifying resins such as alkyd resins, polyester resins, acrylic resins, and epoxy resins, but are not limited to these.

[0042] Alternatively, a cured silicone powder that has absorbed silicone oil (hereinafter, sometimes referred to as "silicone oil-absorbed cured silicone powder") may be used. For example, the silicone oil-absorbed cured silicone powder may be obtained by blending 0.5 to 80% by weight of silicone oil into a fine powder cured silicone, allowing the silicone oil to absorb, and then powdering the mixture by 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.

[0043] Examples of silicone oils include those represented by the following general formula (1): In the following general formula (1), R is a substituted or unsubstituted monovalent hydrocarbon group or a hydroxyl group, and n is an integer. R3SiO[R2SiO] n SiR3(1) In the above general formula (1), R represents 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.

[0044] Polybutylene terephthalate resins tend to have low long-term durability against alkaline solutions. For example, when a resin molded article is used in a location where it comes into contact with chemicals containing sodium hydroxide, sodium hypochlorite, sodium percarbonate, calcium chloride, etc., such as toilet cleaners, bathtub cleaners, bleaches, and snow-melting agents, the resin molded article is exposed to an alkaline atmosphere. If a resin molded article made of polybutylene terephthalate resin is exposed to such an alkaline atmosphere for a long period of time while being subjected to excessive strain due to screwing, metal press-fitting, caulking, etc., the effects of both the strain and the alkaline components can cause so-called environmental stress cracking, resulting in cracks in the molded article. Furthermore, polybutylene terephthalate resin is often used as an insert-molded product in which a metal or inorganic solid (hereinafter also referred to as metal, etc.) is inserted. In such insert-molded products, there is an interface where the resin flows around the metal, etc. and meets during injection molding, known as a weld, and the above-mentioned environmental stress cracking generally occurs in the weld of the molded product.

[0045] From the viewpoint of improving the alkali resistance of the molded product, the kinematic viscosity of the silicone compound (D) at 25°C is 1000 to 10000 cSt (10 to 100 cm 2 / s), more preferably 2000 to 8000 cSt, even more preferably 3000 to 8000 cSt, even more preferably 3000 to 6000 cSt, and even more preferably 4000 to 6000 cSt. When using the silicone oil-absorbed cured silicone powder described above, the silicone oil to be absorbed should have a kinematic viscosity within the above range. The kinematic viscosity at 25°C can be determined by the method described in JIS Z8803.

[0046] The (D) silicone-based compound may be used alone or in combination of two or more.

[0047] The content of the (D) silicone-based compound is preferably 0.5 parts by mass or more and 2 parts by mass or less, more preferably 0.6 parts by mass or more and 1.5 parts by mass or less, and even more preferably 0.7 parts by mass or more and 1.1 parts by mass or less, relative to 100 parts by mass of the (A) polybutylene terephthalate resin.

[0048] From the viewpoint of the effect of improving the alkali resistance of the molded article, the content of the (D) silicone-based compound 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 (A) polybutylene terephthalate resin. On the other hand, from the viewpoint of suppressing problems caused by exudation from the molded article (such as contact contamination), the content of the (D) silicone-based compound 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 (A) polybutylene terephthalate resin.

[0049] (E) Other ingredients The polybutylene terephthalate resin composition of this embodiment may optionally contain components other than the above-mentioned (A) polybutylene terephthalate resin, (B) ethylene-ethyl acrylate copolymer, (C) inorganic filler, and (D) silicone-based compound, depending on the purpose. (E) Other components include, but are not limited to, antioxidants, stabilizers, molecular weight modifiers, ultraviolet absorbers, antistatic agents, colorants, lubricants, mold release agents, crystallization accelerators, crystal nucleating agents, infrared absorbers, flame retardants, flame retardant aids, hydrolysis resistance improvers, flow improvers, and compatibilizers.

[0050] In the polybutylene terephthalate resin composition of the present embodiment, the total content of the above components (A) to (D) is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and even more preferably 95% by mass or more, and may be 99% by mass or more, based on the total composition. The upper limit of the total content of the above components (A) to (D) is not particularly limited and may be 100% by mass. By keeping the total content of the above components (A) to (D) within the above range, it is possible to obtain a resin composition that can be used to mold molded articles with excellent toughness, rigidity, and appearance.

[0051] From the viewpoint of fluidity, the fluidity of polybutylene terephthalate resin composition is measured in accordance with ISO11443, with a furnace temperature of 260°C, a capillary diameter of 1 mm x 20 mm, and a shear rate of 1000 sec -1 The melt viscosity measured by is preferably 0.3 kPa·s or less, more preferably 0.28 kPa·s or less, and even more preferably 0.25 kPa·s or less.

[0052] The polybutylene terephthalate resin composition can be produced by various methods known as methods for producing thermoplastic resin compositions. A suitable method is, for example, a method in which each component is melt-kneaded using a melt-kneading device such as a single-screw or twin-screw extruder, and then extruded into pellets.

[0053] <Molded products> A molded article made using the above-mentioned polybutylene terephthalate resin composition will now be described.

[0054] One embodiment of the present invention relates to a molded article molded using the polybutylene terephthalate resin composition described above. This molded article may, for example, include only a resin part made of the polybutylene terephthalate resin composition, or, for example, as described below, may include a resin part made of the polybutylene terephthalate resin composition and an insert member made of a metal and / or an inorganic solid.

[0055] The method for obtaining a molded article using a polybutylene terephthalate resin composition is not particularly limited, and known methods can be used. For example, a molded article can be obtained by injection molding the polybutylene terephthalate resin composition. For example, the components of the polybutylene terephthalate resin composition can be melt-kneaded and extruded to produce pellets of the polybutylene terephthalate resin composition, which can be then injected into an injection molding machine equipped with a predetermined mold and subjected to injection molding. The molded article of this embodiment can also be an insert-molded article obtained by injection molding the polybutylene terephthalate resin composition together with an insert member made of a metal and / or an inorganic solid.

[0056] The molded article of this embodiment has excellent toughness and rigidity, and also has an excellent appearance. From the viewpoint of obtaining a molded article with a good appearance in which surface roughness is suppressed, the surface roughness of the molded article is preferably 2 μm or less, more preferably 1 μm or less, and even more preferably 0.7 μm or less, as the arithmetic mean roughness Ra according to JIS B 0601-2013.

[0057] The molded article of this embodiment may be applied, for example, to a molded article (more preferably, an insert-molded article) used as a part that comes into contact with an alkaline solution. When applied to a molded article (more preferably, an insert-molded article) used as a part that comes into contact with an alkaline solution, it is particularly preferable to use, as the polybutylene terephthalate resin composition, a polybutylene terephthalate resin composition containing 0.5 to 2 parts by mass of a silicone compound having a kinematic viscosity at 25°C of 1000 to 10000 cSt (more preferably 2000 to 8000 cSt, even more preferably 3000 to 8000 cSt, and even more preferably 4000 to 6000 cSt) per 100 parts by mass of the polybutylene terephthalate resin.

[0058] Embodiments of the present invention include the following, but the present invention is not limited to the following embodiments. <1> (A) 100 parts by mass of a polybutylene terephthalate resin having an intrinsic viscosity of 0.65 to 0.90 dL / g; (B) 5 to 30 parts by mass of ethylene ethyl acrylate copolymer; (C) 10 to 100 parts by mass of an inorganic filler, The polybutylene terephthalate resin composition (B), wherein the ethylene ethyl acrylate copolymer has a melt flow rate of 25 g / 10 min or less at 190° C. under a load of 2.16 kg. <2> The melt flow rate of the (B) ethylene ethyl acrylate copolymer is 5 g / 10 min or less. <1> The polybutylene terephthalate resin composition according to claim 1. <3> Further, (D) a silicone compound having a kinematic viscosity of 3000 to 8000 cSt at 25°C is contained in an amount of 0.5 to 2 parts by mass per 100 parts by mass of the (A) polybutylene terephthalate resin. <1> or <2> The polybutylene terephthalate resin composition according to claim 1. <4> <1> ~ <3> A molded article obtained by using the polybutylene terephthalate resin composition according to any one of claims 1 to 4. <5> Used for parts that come into contact with alkaline solutions. <3> A molded article obtained by using the polybutylene terephthalate resin composition described in 1. <6> The surface roughness is 2 μm or less as the arithmetic mean roughness Ra in accordance with JIS B 0601-2013. <4> or <5> The molded article according to claim 1. [Example]

[0059] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples.

[0060] The components shown in Tables 1 to 3 were mixed in the proportions (parts by mass) shown in the tables, and then melt-kneaded and extruded using a twin-screw extruder (TEX30 manufactured by The Japan Steel Works, Ltd.) at a cylinder temperature of 260°C and a screw rotation of 130 rpm to obtain pellets of a polybutylene terephthalate resin composition. Details of each component used are shown below.

[0061] (1) Polybutylene terephthalate resin (PBT resin) PBT resin A-1: ​​PBT resin manufactured by Polyplastics Co., Ltd. (intrinsic viscosity (IV) = 0.88 dL / g) PBT resin A-2: PBT resin manufactured by Polyplastics Co., Ltd. (intrinsic viscosity (IV) = 0.69 dL / g)

[0062] (2) Ethylene ethyl acrylate copolymer (EEA copolymer) EEA copolymer B-1: Ethylene ethyl acrylate copolymer "NUC-6510" manufactured by ENEOS NUC Corporation (ethyl acrylate content 23% by mass, melt flow rate 0.5 g / 10 min at 190 °C and a load of 2.16 kg) EEA copolymer B-2: Ethylene ethyl acrylate copolymer "NUC-6520" manufactured by ENEOS NUC Corporation (ethyl acrylate content 24% by mass, melt flow rate 1.6 g / 10 min at 190°C and a load of 2.16 kg) EEA copolymer B-3: Ethylene ethyl acrylate copolymer "DPDJ-9169" manufactured by ENEOS NUC Corporation (ethyl acrylate content 20% by mass, melt flow rate 20.0 g / 10 min at 190°C and a load of 2.16 kg) EEA copolymer B-4: Ethylene ethyl acrylate copolymer "NUC-6570" manufactured by ENEOS NUC Corporation (ethyl acrylate content 25% by mass, melt flow rate 20.0 g / 10 min at 190°C and a load of 2.16 kg) EEA copolymer B-5: Ethylene ethyl acrylate copolymer "NUC-6940" manufactured by ENEOS NUC Corporation (ethyl acrylate content 35% by mass, melt flow rate 20.0 g / 10 min at 190°C and a load of 2.16 kg) EEA copolymer B-6: Ethylene ethyl acrylate copolymer "NUC-6070" manufactured by ENEOS NUC Corporation (ethyl acrylate content 25% by mass, melt flow rate 250.0 g / 10 min at 190°C and a load of 2.16 kg) EEA Copolymer B-7: NOF Corporation's ethylene ethyl acrylate and butyl acrylate-methyl methacrylate graft copolymer "Modiper A5300" (melt flow rate 0.1 g / 10 min at 190°C and 2.16 kg load)

[0063] (3) Inorganic fillers Glass fiber (GF): Nippon Electric Glass Co., Ltd. "ECS03T-127" (average fiber diameter 13 μm, average fiber length 3 mm)

[0064] (4) Silicone compounds Silicone compound: Dimethylpolysiloxane with a kinematic viscosity of 5000 cSt at 25°C

[0065] (5) Other Hydrolysis resistance improver (epoxy resin): Mitsubishi Chemical Corporation bisphenol A epoxy resin "jER1004K" Antioxidant: "Irganox 1010" manufactured by BASF Japan Ltd. Colorant (carbon black): "Raven UV-Ultra" manufactured by Columbian Carbon Japan Co., Ltd. Compatibilizer: Ethylene glycidyl methacrylate "Bondfast E" manufactured by Sumitomo Chemical

[0066] <Evaluation> (1) Appearance 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 produce a flat molded piece having a film gate, a hole, and a weld portion, a thickness of 1 mm, and a side length of 80 mm.

[0067] Figure 1 is a schematic diagram of the obtained molded piece. In Figure 1, 10 is the molded piece, 1 is the film gate, 2 is the hole, and 3 is the weld. 4 is the end of the molded piece on the film gate side, and 5 is the end on the opposite side of the hole 2 from end 4. In Figure 1, the line connecting X and X' indicates the measurement range for surface roughness, which will be described later.

[0068] The vicinity of the edge 5 on the upper surface of this molded piece was visually observed and evaluated according to the following criteria. The results are shown in the table. Photographs of reference examples corresponding to the following evaluation criteria A, B, and C are shown in Figure 2. In Figure 2, A shows a photograph of the surface of a molded piece of a reference example corresponding to evaluation criteria A, B shows a photograph of a reference example corresponding to evaluation criteria B, and C shows a photograph of a reference example corresponding to evaluation criteria C. In Figure 2, B and C, the areas surrounded by white frames are areas where whitening was observed. A: No bleaching is observed B: Some bleaching is observed C: Overall bleaching is observed

[0069] (2) Surface roughness A surface roughness measuring device (Mitutoyo Corporation, contour measuring device "Surftest Extreme SV-3000CNC") was used to measure the 4 mm area connecting X and X' of the molded pieces prepared for appearance evaluation, and the arithmetic mean roughness Ra was calculated in accordance with JIS B 0601-2013. The results are shown in the table.

[0070] (3) Alkali resistance Test specimens were prepared by cutting the molded specimens prepared for appearance evaluation into strips 10 mm wide and 80 mm long, with the weld located approximately in the longitudinal center. The test specimens were fixed in a bent state to a jig so that a constant bending strain of 1.0% was applied to the weld. In this state, the jig and the specimens were immersed in a 10% by mass aqueous solution of sodium hydroxide and left at an ambient temperature of 23°C. After 24 hours, the test specimens were observed for cracks. Evaluations were performed using three test specimens for each example and comparative example pellet. The evaluation results are shown in the table. A indicates that no cracks were observed in any of the three test specimens, and B indicates that cracks were observed in at least one of the three test specimens.

[0071] (4) Charpy impact strength (toughness) The resulting polybutylene terephthalate resin composition pellets were dried at 140°C for 3 hours, and then injection molded at a molding temperature of 260°C and a mold temperature of 80°C to prepare Charpy impact test specimens, which were evaluated at 23°C in accordance with the test standards defined in ISO179 / 1eA. The results are shown in the table.

[0072] (5) Melt viscosity The obtained pellets of the polybutylene terephthalate resin composition were subjected to a shear rate of 1000 sec using a Capillograph 1B (manufactured by Toyo Seiki Seisakusho Co., Ltd.) in accordance with ISO 11443, with a furnace temperature of 260°C, a capillary diameter of 1 mm, and a shear rate of 1000 sec. -1 The melt viscosity was measured under the following conditions: The results are shown in the table.

[0073] (6) Flexural modulus (rigidity) The resulting pellets of polybutylene terephthalate resin composition were dried at 140°C for 3 hours and then injection molded at a resin temperature of 260°C and a mold temperature of 80°C to prepare bending test specimens (80mm x 10mm x 4mm) in accordance with ISO 3167. The bending modulus of the prepared test specimens was measured in accordance with ISO 178. The results are shown in the table.

[0074] [Table 1]

[0075] [Table 2]

[0076] [Table 3]

[0077] As shown in Tables 1 to 3, the polybutylene terephthalate resin compositions of Examples 1 to 10 showed excellent results in terms of appearance, surface roughness, Charpy impact strength, and flexural modulus, and it is clear that molded articles excellent in appearance, toughness, and rigidity can be obtained. On the other hand, the compositions of Comparative Examples 1 and 2, which did not contain the EEA copolymer, gave molded articles with low Charpy impact strength.The compositions of Comparative Examples 3 to 5, which used an EEA copolymer with a high melt flow rate at 190°C under a load of 2.16 kg, gave molded articles with poor appearance and high surface roughness.

Claims

1. (A) 100 parts by mass of a polybutylene terephthalate resin having an intrinsic viscosity of 0.65 to 0.90 dL / g; (B) 5 to 30 parts by mass of ethylene ethyl acrylate copolymer; (C) 10 to 100 parts by mass of an inorganic filler; The polybutylene terephthalate resin composition (B) is an ethylene ethyl acrylate copolymer having a melt flow rate of 2 g / 10 min or less at 190° C. under a load of 2.16 kg.

2. 2. The polybutylene terephthalate resin composition according to claim 1, further comprising: (D) a silicone compound having a kinematic viscosity at 25°C of 3000 to 8000 cSt in an amount of 0.5 to 2 parts by mass per 100 parts by mass of the polybutylene terephthalate resin (A).

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

4. A molded article made using the polybutylene terephthalate resin composition according to claim 2, which is used for a part that comes into contact with an alkaline solution.

5. The molded product according to claim 3 or 4, wherein the surface roughness is 2 μm or less as an arithmetic mean roughness Ra in accordance with JIS B 0601-2013.

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