Polyester resin composition and resin molded article

Abstract

To provide a polyester resin composition with excellent releasability.SOLUTION: Disclosed is a polyester resin composition that contains a polybutylene terephthalate resin (A) and a polyethylene terephthalate resin (B). The amount of terminal hydroxyl groups in the polybutylene terephthalate resin (A) is 30-70 mmol / kg based on the total amount of the polybutylene terephthalate resin (A) and the polyethylene terephthalate resin (B).SELECTED DRAWING: None

Description

[Technical Field]

[0001] An embodiment of the present invention relates to a polyester resin composition and a resin molded article. [Background technology]

[0002] Polybutylene terephthalate resin (hereinafter referred to as "PBT resin") has excellent properties such as mechanical properties, electrical properties, heat resistance, chemical resistance, and solvent resistance, and is therefore widely used as an engineering plastic for a variety of applications such as automotive parts and electrical and electronic parts.

[0003] In recent years, there has been an increasing demand for various parts to be smaller, lighter, and have better appearances. Therefore, PBT resin is often alloyed with low-crystalline polyester resins such as polyethylene terephthalate resin (hereinafter also referred to as "PET resin") and polycarbonate resin to improve the appearance (surface gloss, low roughness, etc.) and low warpage of molded products. Patent Documents 1 and 2 describe resin compositions containing a PBT resin and a PET resin. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2020 / 246335 [Patent Document 2] Japanese Patent Application Publication No. 8-183114 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of an embodiment of the present invention is to provide a polyester resin composition having excellent mold releasability. [Means for solving the problem]

[0006] One embodiment of the present invention relates to a polyester resin composition comprising a polybutylene terephthalate resin (A) and a polyethylene terephthalate resin (B), wherein the amount of terminal hydroxyl groups in the polybutylene terephthalate resin (A) is 30 to 70 mmol / kg relative to the total amount of the polybutylene terephthalate resin (A) and the polyethylene terephthalate resin (B). Another embodiment of the present invention relates to a resin molded article obtained using the polyester resin composition described above. [Effects of the Invention]

[0007] According to an embodiment of the present invention, a polyester resin composition having excellent mold releasability can be provided. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 2 is a perspective view schematically showing a molded article used in evaluating demolding properties in the examples. [Figure 2] FIG. 2 is a plan view schematically showing a test piece used for evaluating post-shrinkage in the examples. DETAILED DESCRIPTION OF THE INVENTION

[0009] Preferred embodiments of the present invention will be described below, but the present invention is not limited to the following embodiments.

[0010] <Polyester resin composition> The polyester resin composition of the present embodiment is a polyester resin composition containing a PBT resin (A) and a PET resin (B), in which the amount of terminal hydroxyl groups in the PBT resin (A) is 30 to 70 mmol / kg relative to the total amount of the PBT resin (A) and the PET resin (B).

[0011] Resin compositions containing PBT resin and PET resin tend to undergo transesterification between the PBT resin and the PET resin under high-temperature conditions, such as during melting. If the transesterification reaction proceeds excessively, the melting point and crystallization temperature of the resin composition may change, resulting in a decrease in temperature characteristics such as deflection temperature under load, as well as a decrease in tensile strength and modulus of elasticity, making it impossible to achieve the desired physical properties. Furthermore, if the crystallization temperature changes and crystallization becomes difficult, the amount of shrinkage during injection molding may decrease, the solidification rate may decrease, resulting in reduced rigidity, deformation upon release from the mold, and a longer molding cycle time may result in reduced productivity. Furthermore, if crystallization during injection molding is difficult, crystallization may progress and post-shrinkage may increase if the material is used in a high-temperature environment after molding and assembly. Excessive post-shrinkage may result in deformation due to dimensional changes, widening of gaps between parts, or breakage due to interference between parts.

[0012] The transesterification reaction is a reaction in which the main chain portion is exchanged by a reaction between an ester group and a hydroxyl group. The reaction is affected by the hydroxyl group concentration, but even if the total amount of hydroxyl groups in the resin in the resin composition is small, the mold releasability may not be improved. After extensive research, the inventors have found that the amount of terminal hydroxyl groups in the PBT resin in the resin composition can affect the mold releasability. In this embodiment, the mold releasability can be improved by adjusting the amount of terminal hydroxyl groups in the PBT resin to 30 to 70 mmol / kg relative to the total amount of the PBT resin (A) and the PET resin (B) in the resin composition. Furthermore, the polyester resin composition of the present embodiment may also enable reduction in post-shrinkage of molded articles.

[0013] [Polybutylene terephthalate resin (A)] The PBT resin (A) contains at least terephthalic acid or its ester-forming derivative (C 1-6It is a resin obtained by polycondensation of a dicarboxylic acid component containing an alkylene glycol (such as an alkyl ester or acid halide of 1,4-butanediol) and a glycol component containing an alkylene glycol having at least 4 carbon atoms (such as 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. The PBT resin (A) can be used alone or in combination of two or more.

[0014] From the viewpoint of hydrolysis resistance, the amount of terminal carboxyl groups in the PBT resin (A) is preferably 50 mmol / kg or less, more preferably 40 mmol / kg or less, and even more preferably 30 mmol / kg or less. From the viewpoint of tensile strength, the amount of terminal carboxyl groups in the PBT resin (A) is preferably 3 mmol / kg or more, more preferably 5 mmol / kg or more, and even more preferably 10 mmol / kg or more. The amount of terminal carboxyl groups in the PBT resin (A) is, for example, preferably 3 to 50 mmol / kg, more preferably 5 to 40 mmol / kg, and even more preferably 10 to 30 mmol / kg.

[0015] From the viewpoint of appearance, the amount of terminal hydroxyl groups in the PBT resin (A) is preferably 40 mmol / kg or more, more preferably 60 mmol / kg or more, and even more preferably 80 mmol / kg or more. On the other hand, from the viewpoint of mold releasability, the amount of terminal hydroxyl groups in the PBT resin (A) is preferably 160 mmol / kg or less, more preferably 140 mmol / kg or less, and even more preferably 120 mmol / kg or less. The amount of terminal hydroxyl groups in the PBT resin (A) is, for example, preferably 40 to 160 mmol / kg, more preferably 60 to 140 mmol / kg, and even more preferably 80 to 120 mmol / kg.

[0016] In this specification, the amount of terminal hydroxyl groups in the PBT resin (A) is a value measured by NMR. The amount of terminal hydroxyl groups in the PET resin (B) described later is also a value measured by NMR. The amount of terminal hydroxyl groups in the PBT resin (A) in the polyester resin composition described later and the amount of terminal hydroxyl groups in the PET resin (B) in the polyester resin composition are also values ​​measured by NMR. As the NMR device, for example, Bruker's NMR "AVANCE III 400" can be used.

[0017] The intrinsic viscosity (IV) of the PBT resin (A) is preferably 0.5 dL / g or more and 1.5 dL / g or less, more preferably 0.55 dL / g or more and 1.4 dL / g or less, and even more preferably 0.6 dL / g or more and 1.3 dL / g or less. The intrinsic viscosity can also be adjusted by blending PBT resins with different intrinsic viscosities. For example, a PBT resin with an intrinsic viscosity of 0.9 dL / g can be prepared by blending a PBT resin with an intrinsic viscosity of 0.7 dL / g with a PBT resin with an intrinsic viscosity of 1.1 dL / g. The intrinsic viscosity (IV) of the PBT resin (A) can be measured, for example, in o-chlorophenol at 35°C.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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).

[0022] 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).

[0023] PBT resin (A) can be made from recycled products (material recycling). It can also be made from PBT resin waste that is decomposed to the monomer level (chemical recycling), such as 1,4-butanediol or terephthalic acid, and then polycondensed to produce PBT resin.

[0024] The amount of PBT resin (A) is preferably 20% by mass or more, more preferably 25% by mass or more, and even more preferably 30% by mass or more, based on the total amount of the polyester resin composition. On the other hand, the amount of PBT resin (A) is preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 60% by mass or less, based on the total amount of the polyester resin composition. The amount of PBT resin (A) is, for example, preferably 20 to 80% by mass, more preferably 25 to 70% by mass, and even more preferably 30 to 60% by mass, based on the total amount of the polyester resin composition.

[0025] [Polyethylene terephthalate resin (B)] PET resin (B) is a terephthalic acid or its ester-forming derivative (C 1-6 PET resins are polyester resins obtained by polycondensation of ethylene glycol or its ester-forming derivatives (such as alkyl esters or acid halides) and ethylene glycol or its ester-forming derivatives (such as acetylated products) according to known methods. The main raw materials for PET resins, ethylene glycol and terephthalic acid or terephthalic acid alkyl esters, may be derived from either fossil resources or biomass resources.

[0026] The PET resin (B) may be modified by copolymerizing a small amount of a modifying component that provides repeating units other than terephthaloyl units and ethylenedioxy units, within the scope of the present invention. The amount of repeating units other than terephthaloyl units and ethylenedioxy units contained in the PET resin (B) is preferably less than 4 mol%, more preferably 3 mol% or less, and even more preferably 2 mol% or less, of all repeating units of the polyethylene terephthalate resin.

[0027] The PET resin (B) may contain repeating units derived from the above-mentioned modifying component in an amount of 4 mol % or more of the total repeating units. In this specification, such a polyethylene terephthalate resin may also be referred to as a "modified PET resin."

[0028] The modified PET resin may contain other dicarboxylic acids than terephthalic acid or their ester-forming derivatives (C 1-6 The amount of dicarbonyl units other than terephthaloyl units contained in the modified polyethylene terephthalate resin is preferably 5 mol % or more and 50 mol % or less, more preferably 7 mol % or more and 30 mol % or less, and particularly preferably 10 mol % or more and 25 mol % or less, of all dicarbonyl units.

[0029] Suitable compounds as the dicarboxylic acid or its ester-forming derivative contained in the modifying component include C carboxylic acids 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 acids may be used alone or in combination of two or more.

[0030] Among these dicarboxylic acids or their ester-forming derivatives, C 8-12 Aromatic dicarboxylic acids or their ester-forming derivatives, as well as C such as adipic acid, azelaic acid, and sebacic acid 6-12 In addition, since the resulting polybutylene terephthalate resin composition has excellent metal adhesion and mechanical properties, isophthalic acid or an ester-forming derivative of isophthalic acid (dimethyl isophthalate, diethyl isophthalate, isophthalic acid dichloride, etc.) is particularly preferred as the dicarboxylic acid or an ester-forming derivative thereof in the modifying component.

[0031] The modifying component used in producing the modified PET resin may contain, in addition to a predetermined amount of dicarboxylic acid or an ester-forming derivative thereof, other glycol components such as ethylene glycol and its ester-forming derivatives, a hydroxycarboxylic acid component, a lactone component, etc., within the range that does not impair the object of the present invention. In the modified polyethylene terephthalate resin composition, the amount of repeating units derived from modifying components such as these glycol components, hydroxycarboxylic acid components, and lactone components is preferably 30 mol % or less, more preferably 25 mol % or less, and particularly preferably 20 mol % or less, of all repeating units in the modified polyethylene terephthalate resin.

[0032] The glycol components contained in the modified component include C propylene glycol, trimethylene glycol, 1,4-butanediol, 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.

[0033] The hydroxycarboxylic acid component contained in the modified component may be an aromatic hydroxycarboxylic acid such as 4-hydroxybenzoic acid, 3-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, or 4-carboxy-4'-hydroxybiphenyl; an aliphatic hydroxycarboxylic acid such as glycolic acid or hydroxycaproic acid; or an ester-forming derivative of these hydroxycarboxylic acids (C 1-6 These hydroxycarboxylic acid components can be used alone or in combination of two or more kinds.

[0034] Lactone components contained in the modified components include C such as propiolactone, butyrolactone, valerolactone, and caprolactone (ε-caprolactone, etc.). 3-12 These lactone components can be used alone or in combination of two or more.

[0035] From the viewpoint of appearance, the amount of terminal hydroxyl groups in PET resin (B) is preferably 10 mmol / kg or more, more preferably 20 mmol / kg or more, and even more preferably 30 mmol / kg or more. On the other hand, from the viewpoint of mold releasability, the amount of terminal hydroxyl groups in PET resin (A) is preferably 80 mmol / kg or less, more preferably 70 mmol / kg or less, and even more preferably 60 mmol / kg or less. The amount of terminal hydroxyl groups in PET resin (B) is, for example, preferably 10 to 80 mmol / kg, more preferably 20 to 70 mmol / kg, and even more preferably 30 to 60 mmol / kg.

[0036] PET resin (B) can be a recycled product. If the amount of terminal hydroxyl groups in recycled PET resin (B) is outside the above range, the amount of terminal hydroxyl groups can be adjusted by solid-state polymerization in an inert gas atmosphere such as nitrogen. PET resins produced by decomposing PET resin waste to monomers such as ethylene glycol and terephthalic acid and polycondensing the resulting raw materials can also be used. The PET resin (B) may be used alone or in combination of two or more.

[0037] The amount of PET resin (B) is preferably 10% by mass or more, more preferably 15% by mass or more, and even more preferably 20% by mass or more, based on the total amount of the polyester resin composition. On the other hand, the amount of PET resin (B) is preferably 60% by mass or less, more preferably 50% by mass or less, and even more preferably 40% by mass or less, based on the total amount of the polyester resin composition. The amount of PET resin (B) is, for example, preferably 10 to 60% by mass, more preferably 15 to 50% by mass, and even more preferably 20 to 40% by mass, based on the total amount of the polyester resin composition.

[0038] From the viewpoint of appearance, the mass ratio of the PET resin (B) to the PBT resin (A) (PET resin (B)) / PBT resin (A)) is preferably 0.1 or more, more preferably 0.2 or more, and even more preferably 0.3 or more. From the viewpoint of mold releasability, the mass ratio of the PET resin to the PBT resin (PET resin (B)) / PBT resin (A)) is preferably 0.8 or less, more preferably 0.7 or less, and even more preferably 0.6 or less. The mass ratio of the PET resin to the PBT resin (PET resin (B)) / PBT resin (A)) is, for example, preferably from 0.1 to 0.8, more preferably from 0.2 to 0.7, and even more preferably from 0.3 to 0.6.

[0039] From the viewpoints of improving mold releasability and reducing post-shrinkage of molded articles, the amount of terminal hydroxyl groups in the PBT resin is preferably 30 to 70 mmol / kg relative to the total amount of the PBT resin (A) and the PET resin (B) (total mass of the PBT resin and the PET resin) in the polyester resin composition. In the polyester resin composition, the amount of terminal hydroxyl groups in the PBT resin (A) relative to the total amount of the PBT resin (A) and the PET resin (B) is more preferably 35 to 65 mmol / kg, and even more preferably 40 to 60 mmol / kg.

[0040] In the polyester resin composition, the amount of terminal hydroxyl groups in the PBT resin (A) relative to the total amount of the PBT resin (A) and the PET resin (B) is preferably 70 mmol / kg or less, more preferably 65 mmol / kg or less, and even more preferably 60 mmol / kg or less. On the other hand, in the polyester resin composition, the amount of terminal hydroxyl groups in the PBT resin (A) relative to the total amount of the PBT resin (A) and the PET resin (B) is preferably 30 mmol / kg or more, more preferably 35 mmol / kg or more, and even more preferably 40 mmol / kg or more.

[0041] From the viewpoint of further improving the mold releasability and further reducing the post-shrinkage rate of the molded article, in the polyester resin composition, the sum of the number of terminal hydroxyl groups of the PBT resin (A) and the PET resin (B) relative to the total amount of the PBT resin (A) and the PET resin (B) is preferably 60 to 90 mmol / kg, more preferably 62 to 85 mmol / kg, even more preferably 65 to 75 mmol / kg, and still more preferably 70 to 75 mmol / kg.

[0042] In the polyester resin composition, the sum of the number of terminal hydroxyl groups in the PBT resin (A) and the number of terminal hydroxyl groups in the PET resin (B) relative to the total amount of the PBT resin (A) and the PET resin (B) is preferably 90 mmol / kg or less, more preferably 85 mmol / kg or less, and even more preferably 75 mmol / kg or less. On the other hand, in the polyester resin composition, the sum of the number of terminal hydroxyl groups in the PBT resin and the number of terminal hydroxyl groups in the PET resin (B) relative to the total amount of the PBT resin and the PET resin is preferably 60 mmol / kg or more, more preferably 62 mmol / kg or more, even more preferably 65 mmol / kg or more, and even more preferably 70 mmol / kg or more.

[0043] [Transesterification inhibitor (C)] The polyester resin composition preferably contains a transesterification inhibitor (C) from the viewpoint of inhibiting the transesterification reaction. Examples of the transesterification inhibitor (C) include phosphorus-based compounds such as organic phosphite compounds, phosphonite compounds, and metal phosphates. Specific examples include bis(2,4-di-t-4-methylphenyl)pentaerythritol diphosphite, bis(2,4-di-t-butylphenyl)pentaerythritol diphosphite, tetrakis(2,4-di-t-butylphenyl)-4,4'-biphenylene phosphonite, and 3,9-bis(2,6-di-t-butyl-4-methylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro-[5.5]undecane. Examples of metal phosphates include alkaline earth metal phosphates such as monocalcium phosphate (calcium dihydrogen phosphate) and alkali metal phosphates such as monosodium phosphate (sodium dihydrogen phosphate). The metal phosphate may be, for example, an anhydrous or hydrated form. From the viewpoint of further improving the mold releasability, the polyester resin composition preferably contains a phosphorus-based compound containing a sodium atom or a calcium atom, and more preferably contains a metal phosphate containing a sodium atom or a calcium atom.

[0044] In the polyester resin composition, the content of the transesterification inhibitor (C) is preferably 0.03 to 0.5 mass %, more preferably 0.1 to 0.5 mass %, based on the total amount of the polyester resin composition. For example, in a polyester resin composition, the amount of the phosphorus-based compound containing a sodium atom or a calcium atom is preferably 0.1 to 0.5 mass %, more preferably 0.15 to 0.3 mass %, based on the total amount of the polyester resin composition.

[0045] [Nucleating Agent (D)] The polyester resin composition preferably contains a crystal nucleating agent (D) from the viewpoint of promoting crystallization of the resin. The crystal nucleating agent (D) may be an organic substance, an inorganic substance, or a combination thereof. Examples of inorganic substances include simple substances such as Zn powder, Al powder, graphite, and carbon black; metal oxides such as ZnO, MgO, Al2O3, TiO2, MnO2, SiO2, and Fe3O4; nitrides such as aluminum nitride, silicon nitride, titanium nitride, and boron nitride; inorganic salts such as Na2CO3, CaCO3, MgCO3, CaSiO3, BaSO4, and Ca3(PO4)3; and clays such as talc, kaolin, clay, and white clay. These may be used alone or in combination. Examples of organic substances include organic salts such as calcium oxalate, sodium oxalate, calcium benzoate, calcium phthalate, calcium tartrate, magnesium stearate, and polyacrylates; polymers such as polyester, polyethylene, and polypropylene; and cross-linked polymers, which may be used alone or in combination. Among these, talc, carbon black, and combinations thereof are preferred.

[0046] In the polyester resin composition, the content of the crystal nucleating agent (D) is preferably from 0.05 to 2 mass %, more preferably from 0.1 to 1.5 mass %, and even more preferably from 0.3 to 1 mass %, based on the total amount of the polyester resin composition.

[0047] [Inorganic filler (E)] The polyester resin composition preferably contains an inorganic filler (E), which is preferably a fibrous inorganic filler.

[0048] 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.

[0049] In the polyester resin composition, the inorganic filler (E) is preferably contained in an amount of 5 to 50 mass %, more preferably 10 to 40 mass %, based on the total amount of the polyester resin composition.

[0050] [Other ingredients] The polyester resin composition may contain other components as needed, including, but not limited to, antioxidants, weather stabilizers, molecular weight modifiers, ultraviolet absorbers, antistatic agents, dyes, pigments, lubricants, crystallization accelerators such as plasticizers, near-infrared absorbers, flame retardants, flame retardant assistants, and colorants.

[0051] [Method of producing polyester resin composition] The method for producing the polyester resin composition is not particularly limited, and the polyester resin composition can be produced by various methods known as methods for producing thermoplastic resin compositions.

[0052] A suitable method for producing the polyester resin composition is, for example, a method in which the components are melt-kneaded using a melt-kneading device such as a single-screw or twin-screw extruder, and extruded into pellets.

[0053] <Resin molded products> The resin molded article of this embodiment can be obtained using the polyester resin composition described above.

[0054] The method for producing a resin molded article using the polyester resin composition is not particularly limited, and any known method can be used. For example, the polyester resin composition 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.

[0055] The resin composition of the present embodiment has excellent mold releasability and excellent productivity for resin molded articles. Furthermore, resin molded articles obtained using this resin composition exhibit reduced post-shrinkage under high-temperature conditions and are suitable for use as molded articles exposed to high-temperature, high-humidity environments for long periods of time, such as in automobiles, trains, and the aviation industry. The resin molded articles of the present embodiment can be used for connectors, sensors, actuators, ECU housings, levers, switches, relays, and the like.

[0056] The embodiments of the present invention include the following, but the present invention is not limited to the following embodiments. <1> A polyester resin composition comprising a polybutylene terephthalate resin (A) and a polyethylene terephthalate resin (B), wherein the amount of terminal hydroxyl groups in the polybutylene terephthalate resin (A) is 30 to 70 mmol / kg relative to the total amount of the polybutylene terephthalate resin (A) and the polyethylene terephthalate resin (B). <2> the sum of the amount of terminal hydroxyl groups in the polybutylene terephthalate resin (A) and the amount of terminal hydroxyl groups in the polyethylene terephthalate resin (B) is 60 to 90 mmol / kg relative to the total amount of the polybutylene terephthalate resin (A) and the polyethylene terephthalate resin (B); <1> The polyester resin composition according to claim 1. <3> The polyester resin composition further contains 0.1 to 0.5% by mass of a phosphorus compound containing a sodium atom or a calcium atom, based on the total amount of the polyester resin composition. <1> or <2> The polyester resin composition according to claim 1. <4> Further containing a crystal nucleating agent (D), <1> ~ <3> The polyester resin composition according to any one of claims 1 to 10. <5> The polyester resin composition further contains 5 to 50 mass% of an inorganic filler (E) based on the total mass of the polyester resin composition. <1> ~ <4> The polyester resin composition according to any one of claims 1 to 10. <6> <1> ~ <5> 2. A resin molded article obtained by using the polyester resin composition according to claim 1. [Example]

[0057] 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.

[0058] [Examples 1 to 9, Comparative Examples 1 to 3] The materials listed in Tables 1 to 3 were melt-kneaded and extruded in the ratios (mass%) shown in Tables 1 to 3 using a 30 mmφ twin-screw extruder ("TEX30" manufactured by The Japan Steel Works, Ltd.) at a cylinder temperature of 260°C and a screw rotation speed of 130 rpm to obtain pellets made of the polyester resin compositions of Examples 1 to 9 and Comparative Examples 1 to 3. Details of each component shown in Tables 1 to 3 are provided below.

[0059] (1)PBT resin (A) (A-1): PBT resin: manufactured by Polyplastics Co., Ltd., terminal hydroxyl group content 100 mmol / kg (A-2): PBT resin, manufactured by Polyplastics Co., Ltd., terminal hydroxyl group content 80 mmol / kg (A-3): PBT resin, manufactured by Polyplastics Co., Ltd., terminal hydroxyl group content 120 mmol / kg

[0060] (2)PET resin (B) (B-1): PET resin, Indorama's "N1-100", terminal hydroxyl group content 40 mmol / kg (B-2): PET resin, Indorama "N1", terminal hydroxyl group content 40 mmol / kg

[0061] (3) Inorganic filler (E): Glass fiber, "ECS 03 T-187" manufactured by Nippon Electric Glass Co., Ltd.

[0062] (4) Transesterification inhibitor (C) (C-1): Sodium dihydrogen phosphate, manufactured by Yoneyama Chemical Industry Co., Ltd. (C-2): Phosphite compound, ADEKA Corporation's "ADEKA STAB PEP36" (3,9-bis(2,6-di-t-butyl-4-methylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro-[5.5]undecane)

[0063] (5) Nucleating Agent (D) (D-1): Talc, "Talc Powder PK-NN" manufactured by Hayashi Kasei Co., Ltd. (D-2): Carbon black, Mitsubishi Chemical Corporation "#750B"

[0064] (6) Antioxidant: BASF "IRGANOX 1010" (7) Lubricant: NOF Corporation "Unistar H476"

[0065] In Tables 1 to 3, "PBT terminal hydroxyl group amount (mmol / kg)" refers to the amount (mmol / kg) of terminal hydroxyl groups in PBT resin (A) relative to the total amount of PBT resin (A) and PET resin (B) in the polyester resin composition. "PET terminal hydroxyl group amount (mmol / kg)" refers to the amount (mmol / kg) of terminal hydroxyl groups in PET resin (B) relative to the total amount of PBT resin (A) and PET resin (B) in the polyester resin composition. "Total amount of terminal hydroxyl groups (mmol / kg)" refers to the sum (mmol / kg) of the amount of terminal hydroxyl groups in PBT resin (A) and the amount of terminal hydroxyl groups in PET resin (B) relative to the total amount of PBT resin (A) and PET resin (B) in the polyester resin composition. The amount of terminal hydroxyl groups in PBT resin (A) and the amount of terminal hydroxyl groups in PET resin (B) in the polyester resin composition were measured by NMR using a Bruker NMR apparatus "AVANCE III 400."

[0066] [Table 1]

[0067] [Table 2]

[0068] [Table 3]

[0069] <Evaluation method>

[0070] (1) Cooling time (mold releasability) For the resin compositions in Tables 1 to 3, molded articles having the shape shown in FIG. 1 were molded using Toshiba Corporation's "EC40," and the minimum time required for release at a dwell pressure of 70 MPa (cooling time (seconds)) was measured. A shorter cooling time indicates better release properties. The results (cooling time (seconds)) are shown in the tables. The molding conditions are as follows:

[0071] (Molding conditions) Cylinder temperature: 250℃ Mold temperature: 60℃ Injection speed: 20mm / sec Injection and pressure holding: 5 seconds

[0072] Figure 1 is a perspective view showing a molded product used in the evaluation of cooling time (mold releasability). In Figure 1, 1 denotes the molded product, 2 denotes the short side, 3 denotes the cylinder, 4 denotes the long side, and 5 denotes the ejector pin protrusion area. The molded product 1 has a thin, T-shaped shape (long side 4: length 30 mm, width 15 mm, thickness 1 mm; short side 2: height 10 mm, width 15 mm, central thickness 2 mm, maximum thickness 3 mm). A cylinder 3 (diameter 3 mm, height 7 mm) is installed on one side of the long side 4. Furthermore, an ejector pin (not shown) is set to protrude from the ejector pin protrusion area 5 in the center of the other side of the long side 4.

[0073] (2) Post-shrinkage rate For the resin compositions in Tables 1 to 3, test specimens measuring 120 mm × 120 mm × 2 mm (thickness) were molded at a cylinder temperature of 260°C and a mold temperature of 60°C. The change in the test specimen dimensions in the direction perpendicular to the flow (post-shrinkage) was determined before and after annealing at 140°C for 3 hours. FIG. 2 is a plan view schematically showing the shape of the test specimen. In FIG. 2, 10 indicates the test specimen, X indicates the direction perpendicular to the flow, and Y indicates the flow direction. Also in FIG. 2, L indicates the location where the dimension in the direction perpendicular to the flow was measured. Specifically, the dimension (mm) in the direction perpendicular to the flow was measured at the location indicated by L in FIG. 2 after molding of the test specimen and before annealing, and after annealing. These were defined as the dimension (mm) in the direction perpendicular to the flow before annealing and the dimension (mm) in the direction perpendicular to the flow after annealing, respectively. The post-shrinkage (%) in the direction perpendicular to the flow was calculated using the following formula:

[0074] Post-shrinkage rate in the direction perpendicular to the flow (%) = [(dimension in the direction perpendicular to the flow before annealing (mm)) - (dimension in the direction perpendicular to the flow after annealing (mm))] ÷ 120 (mm) × 100

[0075] For each resin composition, the dimension (mm) in the direction perpendicular to the flow before annealing, the dimension (mm) in the direction perpendicular to the flow after annealing, and the post-shrinkage rate (%) in the direction perpendicular to the flow are shown in the table.

[0076] As shown in the table, in Examples 1 to 9 in which the amount of terminal hydroxyl groups in the PBT resin (A) relative to the total amount of the PBT resin (A) and the PET resin (B) is 30 to 70 mmol / kg, excellent results were shown in both the evaluation of the cooling demolding time and the post-shrinkage rate, and it is clear that the molded article has excellent demolding properties and can be reduced in post-shrinkage after being exposed to high-temperature conditions, etc. [Explanation of symbols]

[0077] 1 Molded product 2 Short side 3 Cylinder 4 Long side 5 Eject pin protruding part 10 test specimens X Flow direction Y flow direction

Claims

1. The composite material contains a polybutylene terephthalate resin (A), a polyethylene terephthalate resin (B), and a fibrous inorganic filler, the amount of terminal hydroxyl groups in the polybutylene terephthalate resin (A) is 30 to 70 mmol / kg relative to the total amount of the polybutylene terephthalate resin (A) and the polyethylene terephthalate resin (B); The amount of the fibrous inorganic filler is 10 to 50% by mass based on the total amount of the polyester resin composition. Polyester resin composition.

2. 2. The polyester resin composition according to claim 1, wherein the sum of the amount of terminal hydroxyl groups of the polybutylene terephthalate resin (A) and the amount of terminal hydroxyl groups of the polyethylene terephthalate resin (B) is 60 to 90 mmol / kg relative to the total amount of the polybutylene terephthalate resin (A) and the polyethylene terephthalate resin (B).

3. 3. The polyester resin composition according to claim 1, further comprising 0.1 to 0.5 mass% of a phosphorus-based compound containing a sodium atom or a calcium atom, based on the total amount of the polyester resin composition.

4. The polyester resin composition according to claim 1 or 2, further comprising a crystal nucleating agent (D).

5. 3. The polyester resin composition according to claim 1, wherein the mass ratio of the polyethylene terephthalate resin (B) to the polybutylene terephthalate resin (A) (polyethylene terephthalate resin (B) / polybutylene terephthalate resin (A)) is 0.47 or more.

6. The polyester resin composition according to claim 1 or 2, wherein the fibrous inorganic filler comprises glass fiber, carbon fiber, or a combination thereof.

7. A resin molded product obtained using the polyester resin composition according to claim 1 or 2.

Images