Polyester resin composition and resin molded article

Abstract

This polyester resin composition contains a polybutylene terephthalate resin, a recycled polyethylene terephthalate resin, a transesterification inhibitor, a carbodiimide compound, and an elastomer. The amount of terminal hydroxyl groups in the polybutylene terephthalate resin is 30-70 mmol / kg relative to the total amount of the polybutylene terephthalate resin and the recycled polyethylene terephthalate resin. The amount of the carbodiimide compound is 0.2-1.5 mass% relative to the total amount of the polyester resin composition. The amount of the elastomer is 3-15 mass% relative to the total amount of the polyester resin composition.

Description

Polyester resin composition and resin molded product

[0001] Embodiments of the present invention relate to polyester resin compositions and resin molded articles.

[0002] In recent years, highly recyclable resins have been in demand for the realization of a sustainable society. Resins such as polyethylene, polystyrene, polypropylene, and polyethylene terephthalate, which are used in packaging and containers, have a high polymer ratio in packaging containers, so waste collected from the market is crushed, washed, and repelled to be used as recycled products. On the other hand, polybutylene terephthalate resin (hereinafter also called PBT resin) is often used with various additives such as inorganic fillers, impact modifiers, and flame retardants added according to market demands, so the polymer ratio of polybutylene terephthalate resin itself is low, making it difficult to obtain stable quality in the aforementioned processes. For this reason, methods such as recovering energy through thermal recycling or decomposing the polymer through chemical recycling and reusing the recovered monomers by polymerization or as raw materials for other substances have been considered, but these methods consume a lot of energy and have not been widely adopted.

[0003] Therefore, studies are underway to increase the proportion of recycled plastics used in polybutylene terephthalate resin compositions by blending readily available recycled resins, such as recycled polyethylene terephthalate resin (hereinafter also referred to as recycled PET resin) and recycled polystyrene resin, with polybutylene terephthalate resin.

[0004] Blending polyethylene terephthalate resin (hereinafter also referred to as PET resin) or polystyrene resin with polybutylene terephthalate resin is commonly used for purposes such as improving dimensional accuracy, reducing warping, and improving appearance. However, since polystyrene resin reduces heat resistance, polyethylene terephthalate resin, which has a high melting point, is used in automotive parts and electrical equipment such as induction cooktops where heat resistance is required. However, polyethylene terephthalate resin inhibits the crystallization of polybutylene terephthalate resin, which poses problems in moldability. In addition, since polyethylene terephthalate has inferior hydrolysis resistance compared to polybutylene terephthalate, when blending recycled PET resin and polybutylene terephthalate resin from an environmental perspective, there are durability problems due to the reduced hydrolysis resistance.

[0005] Patent Document 1 describes that a resin composition containing polybutylene terephthalate resin, polyethylene terephthalate resin, inorganic filler, non-carbon black pigment, organic dye, and polycarbodiimide compound has design properties and heat resistance, and that a mold release agent may be added to the resin composition to improve mold release properties.

[0006] Japanese Patent Publication No. 2017-008149

[0007] Patent Document 1 does not show improvement in mold release properties when a mold release agent is added. Furthermore, even when a mold release agent is added, sufficient mold release properties are sometimes not obtained. The object of the embodiments of the present invention is to provide a recycled polyester resin composition that has excellent hydrolysis resistance and mold release properties.

[0008] One embodiment of the present invention relates to a polyester resin composition comprising a polybutylene terephthalate resin, a recycled polyethylene terephthalate resin, a transesterification inhibitor, a carbodiimide compound, and an elastomer, wherein the amount of terminal hydroxyl groups of the polybutylene terephthalate resin is 30 to 70 mmol / kg relative to the total amount of the polybutylene terephthalate resin and the recycled polyethylene terephthalate resin, the amount of the carbodiimide compound is 0.2 to 1.5% by mass relative to the total amount of the polyester resin composition, and the amount of the elastomer is 3 to 15% by mass relative to the total amount of the polyester resin composition. Another embodiment of the present invention relates to a resin molded article obtained using the above-described polyester resin composition.

[0009] According to embodiments of the present invention, a polyester resin composition with excellent hydrolysis resistance and mold release properties can be provided.

[0010] This is a schematic perspective view showing the molded product used to evaluate the release properties in the example.

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

[0012] <Polyester Resin Composition> The polyester resin composition of this embodiment comprises PBT resin, recycled PET resin, transesterification inhibitor, carbodiimide compound, and elastomer, wherein the amount of terminal hydroxyl groups of the PBT resin is 30 to 70 mmol / kg relative to the total amount of PBT resin and recycled PET resin, the amount of the carbodiimide compound is 0.2 to 1.5% by mass relative to the total amount of the polyester resin composition, and the amount of elastomer is 3 to 15% by mass relative to the total amount of the polyester resin composition.

[0013] In resin compositions containing PBT resin and PET resin, transesterification reactions tend to occur easily between the PBT resin and PET resin under high-temperature conditions such as during melting. If the transesterification reaction proceeds too far, the melting point and crystallization temperature of the resin composition change, and temperature characteristics such as the temperature of deflection under load, as well as tensile strength and elastic modulus, may decrease, making it impossible to obtain the expected physical properties. Furthermore, if the crystallization temperature changes and crystallization becomes difficult, the amount of shrinkage during injection molding decreases, the solidification rate decreases, rigidity decreases, deformation occurs when releasing from the mold, and productivity decreases due to longer molding cycle times. The same applies when PET resin is replaced with recycled PET resin. Transesterification is a reaction in which the main chain is replaced by the reaction of ester groups and hydroxyl groups, and is affected by the hydroxyl group concentration, but even if the total amount of hydroxyl groups in the resin composition is small, the release properties may not improve.

[0014] The polyester resin composition of this embodiment comprises PBT resin, recycled PET resin, transesterification inhibitor, carbodiimide compound, and elastomer, wherein the amount of terminal hydroxyl groups of the PBT resin is 30 to 70 mmol / kg relative to the total amount of PBT resin and recycled PET resin, the amount of the carbodiimide compound is 0.2 to 1.5% by mass relative to the total amount of the polyester resin composition, and the amount of elastomer is 3 to 15% by mass relative to the total amount of the polyester resin composition. This polyester resin composition exhibits excellent mold release properties and excellent hydrolysis resistance.

[0015] [Polybutylene terephthalate resin] PBT resin contains at least terephthalic acid or its ester-forming derivative (C １－６The resin is obtained by polycondensation of a dicarboxylic acid component containing alkyl esters or acid halides (such as 1,4-butanediol) and a glycol component containing alkylene glycol (1,4-butanediol) having at least four carbon atoms or its ester-forming derivative (such as an acetylated compound). The PBT resin is not limited to homopolybutylene terephthalate resin, but may also be a copolymer containing 60 mol% or more (particularly 75 mol% to 95 mol%) of butylene terephthalate units. Furthermore, in this embodiment, the raw materials for the PBT resin, 1,4-butanediol or its ester-forming derivative and terephthalic acid or its ester-forming derivative (e.g., alkyl terephthalate ester), may be derived from either fossil resources or biomass resources. The PBT resin can be used alone or in combination of two or more types.

[0016] From the viewpoint of hydrolysis resistance, the amount of terminal carboxyl groups in PBT resin 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 PBT resin is preferably 3 mmol / kg or more, more preferably 5 mmol / kg or more, and even more preferably 10 mmol / kg or more. For example, the amount of terminal carboxyl groups in PBT resin is preferably 3 to 50 mmol / kg, more preferably 5 to 40 mmol / kg, and even more preferably 10 to 30 mmol / kg.

[0017] From the viewpoint of appearance, the amount of terminal hydroxyl groups in the PBT resin 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 release properties, the amount of terminal hydroxyl groups in the PBT resin is preferably 160 mmol / kg or less, more preferably 140 mmol / kg or less, and even more preferably 120 mmol / kg or less. For example, the amount of terminal hydroxyl groups in the PBT resin is preferably 40 to 160 mmol / kg, more preferably 60 to 140 mmol / kg, and even more preferably 80 to 120 mmol / kg.

[0018] In this specification, the amount of terminal hydroxyl groups in PBT resin is a value measured by NMR. Similarly, the amount of terminal hydroxyl groups in recycled PET resin, as described later, is also a value measured by NMR. Furthermore, the amount of terminal hydroxyl groups in PBT resin and recycled PET resin in polyester resin compositions, as described later, are also values ​​measured by NMR. As an NMR apparatus, for example, a Bruker NMR "AVANCE III 400" can be used.

[0019] The intrinsic viscosity (IV) of PBT resin 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. Furthermore, the intrinsic viscosity can be adjusted by blending PBT resins having different intrinsic viscosities. For example, a PBT resin with an intrinsic viscosity of 0.9 dL / g can be prepared by blending a PBT fat 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 PBT resin can be measured, for example, in o-chlorophenol at a temperature of 35°C.

[0020] In PBT resin, dicarboxylic acid components (comonomer components) other than terephthalic acid and its ester-forming derivatives include, for example, isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-dicarboxydiphenyl ether, etc. ８－１４ Aromatic dicarboxylic acids; such as succinic acid, adipic acid, azelaic acid, sebacic acid, etc. ４－１６ C alkanedicarboxylic acids; cyclohexanedicarboxylic acids, etc. ５－１０ Cycloalkanedicarboxylic acids; ester-forming derivatives of these dicarboxylic acid components (C １－６ Examples include alkyl ester derivatives and acid halides. These dicarboxylic acid components can be used individually or in combination of two or more.

[0021] Among these dicarboxylic acid components, C such as isophthalic acid ８－１２ Aromatic dicarboxylic acids, and C such as adipic acid, azelaic acid, and sebacic acid. ６－１２ Alkane dicarboxylic acids are more preferred.

[0022] In PBT resin, examples of glycol components (comonomer components) other than 1,4-butanediol and its ester-forming derivatives include alkylene glycols such as ethylene glycol, propylene glycol, trimethylene glycol, 1,3-butylene glycol, hexamethylene glycol, neopentyl glycol, 1,3-octanediol, etc. with C ２－１０ alkylene glycols; polyoxyalkylene glycols such as diethylene glycol, triethylene glycol, dipropylene glycol, etc.; alicyclic diols such as cyclohexanedimethanol, hydrogenated bisphenol A, etc.; aromatic diols such as bisphenol A, 4,4'-dihydroxybiphenyl, etc.; C ２－４ alkylene oxide adducts of bisphenol A such as 2-mole adduct of ethylene oxide to bisphenol A, 3-mole adduct of propylene oxide to bisphenol A, etc.; or ester-forming derivatives (such as acetylated products) of these glycols. These glycol components can be used alone or in combination of two or more.

[0023] Among these glycol components, C ２－６ alkylene glycols such as ethylene glycol, trimethylene glycol, etc., polyoxyalkylene glycols such as diethylene glycol, etc., or alicyclic diols such as cyclohexanedimethanol, etc. are more preferable. Examples of comonomer components that can be used in addition to the dicarboxylic acid component and the glycol component include aromatic hydroxycarboxylic acids such as 4-hydroxybenzoic acid, 3-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, 4-carboxy-4'-hydroxybiphenyl, etc.; aliphatic hydroxycarboxylic acids such as glycolic acid, hydroxycaproic acid, etc.; C ３－１２ lactones such as propiolactone, butyrolactone, valerolactone, caprolactone (ε-caprolactone, etc.); ester-forming derivatives (C １－６ alkyl ester derivatives, acid halides, acetylated products, etc.) of these comonomer components.

[0024] Any of the polybutylene terephthalate copolymers obtained by copolymerizing the comonomer components described above can be suitably used as a PBT resin. Further, as the PBT resin, a combination of a homopolybutylene terephthalate polymer and a polybutylene terephthalate copolymer may be used.

[0025] Market recycled products can be used for the PBT resin (material recycling). Further, PBT resin obtained by decomposing 1,4-butanediol, terephthalic acid, etc. from PBT resin waste to the monomer level (chemical recycling) and polycondensing the obtained raw materials can also be used.

[0026] The amount of the PBT resin is preferably 20% by mass or more, more preferably 25% by mass or more, and still more preferably 30% by mass or more, based on the total amount of the polyester resin composition. On the other hand, the amount of the PBT resin is preferably 60% by mass or less, more preferably 50% by mass or less, and still more preferably 40% by mass or less, based on the total amount of the polyester resin composition. The amount of the PBT resin is preferably, for example, 20 to 60% by mass, more preferably 25 to 50% by mass, and still more preferably 30 to 40% by mass, based on the total amount of the polyester resin composition.

[0027] [Recycled polyethylene terephthalate resin] The recycled PET resin is a polyester resin obtained by polycondensing terephthalic acid or its ester-forming derivative (C １－６ alkyl ester, acid halide, etc.) and ethylene glycol or its ester-forming derivative (acetyl化物等) according to a known method, and market recycled products such as PET bottles, PET fibers, and films can be used.

[0028] The recycled PET resin may be modified by copolymerizing a small amount of a modifying component that gives repeating units other than terephthaloyl units and ethylene dioxy units within a range that does not inhibit the object of the present invention. The amount of repeating units other than terephthaloyl units and ethylene dioxy units contained in the recycled PET resin is preferably less than 4 mol%, more preferably 3 mol% or less, and still more preferably 2 mol% or less, based on all the repeating units of the polyethylene terephthalate resin.

[0029] Furthermore, recycled PET resin may contain 4 mol% or more of repeating units derived from the above-mentioned modified components out of the total repeating units. In this specification, such polyethylene terephthalate resin may also be referred to as "modified PET resin".

[0030] The modified PET resin contains other dicarboxylic acids of terephthalic acid or their ester-forming derivatives (C) to the extent that it does not hinder the objectives of the present invention. １－６ The modified polyethylene terephthalate resin may contain dicarbonyl units derived from alkyl esters, acid halides, etc. The amount of other dicarbonyl units in the modified polyethylene terephthalate resin is preferably 5 mol% to 50 mol%, more preferably 7 mol% to 30 mol%, and particularly preferably 10 mol% to 25 mol% of the total dicarbonyl units.

[0031] Suitable compounds as dicarboxylic acids or their ester-forming derivatives included in the modified component include isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-dicarboxydiphenyl ether, etc. ８－１４ Aromatic dicarboxylic acids; such as succinic acid, adipic acid, azelaic acid, sebacic acid, etc. ４－１６ C alkanedicarboxylic acids; cyclohexanedicarboxylic acids, etc. ５－１０ Cycloalkanedicarboxylic acids; ester-forming derivatives of these dicarboxylic acid components (C １－６ Examples include alkyl ester derivatives and acid halides. These dicarboxylic acids can be used individually or in combination of two or more.

[0032] Among these dicarboxylic acids or their esterifying derivatives, C such as isophthalic acid ８－１２ Aromatic dicarboxylic acids or their ester-forming derivatives, as well as C such as adipic acid, azelaic acid, and sebacic acid. ６－１２Alkane dicarboxylic acids or their ester-forming derivatives are more preferred. Furthermore, since the resulting polybutylene terephthalate resin composition exhibits excellent metal adhesion and mechanical properties, isophthalic acid or ester-forming derivatives of isophthalic acid (such as dimethyl isophthalate, diethyl isophthalate, and dichloride isophthalate) are particularly preferred as the dicarboxylic acid or its ester-forming derivative in the modified component.

[0033] The modifying components used in the production of the modified PET resin may contain, in addition to a predetermined amount of dicarboxylic acid or its ester-forming derivative, other glycol components, hydroxycarboxylic acid components, lactone components, etc., of ethylene glycol and its ester-forming derivatives, to the extent that they do not hinder the objectives of the present invention. In the modified polyethylene terephthalate resin, the amount of repeating units derived from these modifying components, such as 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 the total repeating units in the modified polyethylene terephthalate resin.

[0034] Glycol components included in the modified components include 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; bisphenol A C2 adducts such as bisphenol A ethylene oxide 2-mol adduct and bisphenol A propylene oxide 3-mol adduct. ２－４ Examples include alkylene oxide adducts of these glycols; or ester-forming derivatives of these glycols (such as acetylated compounds). These glycol components can be used individually or in combination of two or more.

[0035] The hydroxycarboxylic acid components included in the modified components are 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; or ester-forming derivatives of these hydroxycarboxylic acids (C １－６ Examples include alkyl ester derivatives, acid halides, acetylated compounds, etc. These hydroxycarboxylic acid components can be used individually or in combination of two or more.

[0036] The lactone components included in the modified components are propiolactone, butyrolactone, valerolactone, caprolactone (ε-caprolactone, etc.), etc. ３－１２ Lactones are examples. These lactone components can be used individually or in combination of two or more.

[0037] From the viewpoint of appearance, the amount of terminal hydroxyl groups in recycled PET resin 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 release properties, the amount of terminal hydroxyl groups in recycled PET resin is preferably 80 mmol / kg or less, more preferably 70 mmol / kg or less, and even more preferably 60 mmol / kg or less. For example, the amount of terminal hydroxyl groups in recycled PET resin is preferably 10 to 80 mmol / kg, more preferably 20 to 70 mmol / kg, and even more preferably 30 to 60 mmol / kg.

[0038] If the amount of terminal hydroxyl groups in recycled PET resin recovered from the market falls outside the aforementioned range, the amount of terminal hydroxyl groups may be adjusted by solid-phase polymerization in an inert gas atmosphere such as nitrogen. Furthermore, PET resin produced by decomposing PET resin waste down to monomer levels such as ethylene glycol and terephthalic acid, and then polycondensing the resulting raw materials, can also be used. Recycled PET resin may be used individually or in combination of two or more types.

[0039] From an environmental standpoint, the amount of recycled PET resin is preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 25% by mass or more, relative to the total amount of the polyester resin composition. On the other hand, from the viewpoint of hydrolysis resistance, the amount of recycled PET resin is preferably 45% by mass or less, more preferably 40% by mass or less, and even more preferably 35% by mass or less, relative to the total amount of the polyester resin composition. For example, the amount of recycled PET resin is preferably 10 to 45% by mass, more preferably 20 to 40% by mass, and even more preferably 25 to 35% by mass, relative to the total amount of the polyester resin composition.

[0040] From the viewpoint of improving mold release properties, in a polyester resin composition, the amount of terminal hydroxyl groups of PBT resin relative to the total amount of PBT resin and recycled PET resin (sum of the mass of PBT resin and recycled PET resin) is preferably 30 to 70 mmol / kg. In a polyester resin composition, the amount of terminal hydroxyl groups of PBT resin relative to the total amount of PBT resin and recycled PET resin is more preferably 35 to 65 mmol / kg, and even more preferably 40 to 60 mmol / kg.

[0041] In a polyester resin composition, the amount of terminal hydroxyl groups of PBT resin relative to the total amount of PBT resin and recycled PET resin 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 a polyester resin composition, the amount of terminal hydroxyl groups of PBT resin relative to the total amount of PBT resin and recycled PET resin is preferably 30 mmol / kg or more, more preferably 35 mmol / kg or more, and even more preferably 40 mmol / kg or more.

[0042] From the viewpoint of further improving mold release properties, in the polyester resin composition, the total amount of terminal hydroxyl groups of the PBT resin and the recycled PET resin relative to the total amount of PBT resin and recycled PET resin 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.

[0043] In a polyester resin composition, the total amount of terminal hydroxyl groups in the PBT resin and the recycled PET resin, relative to the total amount of PBT resin and recycled PET resin, 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 a polyester resin composition, the total amount of terminal hydroxyl groups in the PBT resin and the recycled PET resin, relative to the total amount of PBT resin and recycled 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.

[0044] [Transesterification Inhibitors] From the viewpoint of suppressing transesterification reactions, it is preferable that the polyester resin composition contains a transesterification inhibitor. Examples of transesterification inhibitors include organic phosphite compounds, phosphate compounds, and phosphorus compounds such as metal phosphate salts. 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 phosphate, 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 phosphate salts 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 salt may be, for example, an anhydrous or a hydrated form. From the viewpoint of further improving mold release properties, the polyester resin composition preferably contains a phosphorus compound containing a sodium atom or a calcium atom, and more preferably contains a metal phosphate salt containing a sodium atom or a calcium atom.

[0045] In a polyester resin composition, the amount of transesterification inhibitor is preferably 0.03 to 0.5% by mass, and more preferably 0.1 to 0.5% by mass, based on the total amount of the polyester resin composition. For example, in a polyester resin composition, the amount of phosphorus-based compound containing sodium atoms or calcium atoms is preferably 0.1 to 0.5% by mass, and more preferably 0.15 to 0.3% by mass, based on the total amount of the polyester resin composition.

[0046] [Carbodiimide Compounds] Carbodiimide compounds are compounds having a carbodiimide group (-N=C=N-) in their molecule. Examples of carbodiimide compounds include aliphatic carbodiimide compounds with an aliphatic main chain, alicyclic carbodiimide compounds with an alicyclic main chain, and aromatic carbodiimide compounds with an aromatic main chain. It is preferable to use one or more selected from these. From the viewpoint of hydrolysis resistance, aromatic carbodiimide compounds are superior, and alicyclic carbodiimides are superior in that they do not generate isocyanate gas, which is harmful to the human body. By combining both, it is possible to create a polyester resin composition with excellent hydrolysis resistance and low isocyanate gas generation.

[0047] Examples of aliphatic carbodiimide compounds include diisopropylcarbodiimide and dioctyldecylcarbodiimide. Examples of alicyclic carbodiimide compounds include dicyclohexylcarbodiimide. Two or more of these can also be used in combination.

[0048] Aromatic carbodiimide compounds include diphenylcarbodiimide, di-2,6-dimethylphenylcarbodiimide, di-2,6-diisopropylphenylcarbodiimide, N-toluyl-N'-phenylcarbodiimide, di-p-nitrophenylcarbodiimide, di-p-aminophenylcarbodiimide, di-p-hydroxyphenylcarbodiimide, di-p-chlorophenylcarbodiimide, di-p-methoxyphenylcarbodiimide, di-3,4-dichlorophenylcarbodiimide, di-2,5-dichlorophenylcarbodiimide, di-o-chlorophenylcarbodiimide, p-phenylene-bis-di-o-toluylcarbodiimide, p-phenylene-bis-dicyclohexylcarbodiimide, and p-phenylene-bis-di-p-chlorophenylcarbodiimide. Examples include mono- or dicarbodiimide compounds such as rubodiimide and ethylene-bis-diphenylcarbodiimide; and polycarbodiimide compounds such as poly(4,4'-diphenylmethanecarbodiimide), poly(3,5'-dimethyl-4,4'-biphenylmethanecarbodiimide), poly(p-phenylenecarbodiimide), poly(m-phenylenecarbodiimide), poly(3,5'-dimethyl-4,4'-diphenylmethanecarbodiimide), poly(naphthylenecarbodiimide), poly(1,3-diisopropylphenylenecarbodiimide), poly(1-methyl-3,5-diisopropylphenylenecarbodiimide), poly(1,3,5-triethylphenylenecarbodiimide), and poly(triisopropylphenylenecarbodiimide). Two or more of these can also be used in combination. Among these, one or more selected from di-2,6-dimethylphenylcarbodiimide, poly(4,4'-diphenylmethanecarbodiimide), poly(phenylenecarbodiimide), and poly(triisopropylphenylenecarbodiimide) can be preferably used.

[0049] In the polyester resin composition, the amount of carbodiimide compound is 0.2 to 1.5% by mass, preferably 0.3 to 1.2% by mass, relative to the total amount of the polyester resin composition. From the viewpoint of improving hydrolysis resistance, the amount of carbodiimide compound added is preferably 0.2% by mass or more, and more preferably 0.3% by mass or more, relative to the total amount of the polyester resin composition. From the viewpoint of fluidity, the amount of carbodiimide compound added is preferably 1.5% by mass or less, and more preferably 1.2% by mass or less, relative to the total amount of the polyester resin composition.

[0050] [Elastomer] In this embodiment, olefin-based elastomers and core-shell elastomers are preferred as the elastomer.

[0051] The amount of elastomer added is 3 to 15% by mass of the total polyester resin composition, preferably about 5 to 12% by mass. From the viewpoint of improving hydrolysis resistance, the amount of elastomer added is preferably 3% by mass or more, and more preferably 5% by mass or more, of the total polyester resin composition. From the viewpoint of improving mold release properties, the amount of elastomer added is preferably 15% by mass or less, and more preferably 12% by mass or less, of the total polyester resin composition.

[0052] Examples of olefin-based elastomers include ethylene-propylene copolymers (EP copolymers), ethylene-butene copolymers, ethylene-octene copolymers, ethylene-propylene-diene copolymers (EPD copolymers), ethylene-propylene-butene copolymers, ethylene-vinyl acetate copolymers, copolymers containing at least one unit selected from EP copolymers and EPD copolymers, and copolymers of olefins and (meth)acrylic monomers (ethylene-ethyl acrylate copolymers, ethylene-glycidyl methacrylate copolymers, etc.). Preferred olefin-based elastomers include EP copolymers, EPD copolymers, and copolymers of olefins and (meth)acrylic monomers, with ethylene ethyl acrylate being particularly preferred from the viewpoint of mold release properties. These olefin-based elastomers can be used alone or in combination of two or more types.

[0053] Core-shell elastomers are polymers composed of a core layer made up of a rubber component (soft component) and a shell layer made up of a hard component, with acrylic rubber being used as the rubber component of the core layer. The rubber component used in the core layer preferably has a glass transition temperature (Tg) of less than 0°C (e.g., -10°C or lower), more preferably -20°C or lower (e.g., -180°C or higher and -25°C or lower), and particularly preferably -30°C or lower (e.g., -150°C or higher and -40°C or lower).

[0054] When using acrylic rubber as the rubber component, polymers obtained by polymerizing acrylic monomers such as alkyl acrylates as the main component are preferred. The alkyl acrylate used as the monomer for the acrylic rubber is preferably a C1 to C12 alkyl ester of acrylic acid, such as butyl acrylate, and more preferably a C2 to C6 alkyl ester of acrylic acid.

[0055] Acrylic rubber may be a homopolymer or copolymer of acrylic monomers. If the acrylic rubber is a copolymer of acrylic monomers, it may be a copolymer of acrylic monomers with other acrylic monomers, or a copolymer of acrylic monomers with other unsaturated bond-containing monomers. If the acrylic rubber is a copolymer, it may also be a copolymer of crosslinkable monomers.

[0056] Vinyl polymers are preferably used for the shell layer. 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 layer and shell layer of such a core-shell elastomer may be bonded together by graft copolymerization. This graft copolymerization is obtained by adding a graft cross-agent that reacts with the shell layer during polymerization of the core layer, if necessary, to provide reactive groups to the core layer, and then forming the shell layer. When silicone rubber is used as the graft cross-agent, an organosiloxane having vinyl bonds or an organosiloxane having thiols is used, preferably acryloxysiloxane, methacryloxysiloxane, or vinylsiloxane.

[0057] [Crystal Nucleating Agent] From the viewpoint of promoting the crystallization of the resin, the polyester resin composition preferably contains a crystal nucleating agent. The crystal nucleating agent may be an organic substance, an inorganic substance, or a combination thereof. Examples of inorganic substances include individual elements such as Zn powder, Al powder, graphite, and carbon black, or ZnO, MgO, and Al ２ O ３ , TiO ２ MnO ２ SiO ２ Fe ３ O ４ Metal oxides such as aluminum nitride, silicon nitride, titanium nitride, boron nitride, and other nitrides, Na ２ CO ３ CaCO ３ , MgCO ３ CaSiO ３ , BaSO ４ Ca ３ (PO ４ ) ３ Inorganic salts such as talc, kaolin, clay, and white clay can be used individually or in combination of two or more. Organic materials such as calcium oxalate, sodium oxalate, calcium benzoate, calcium phthalate, calcium tartrate, magnesium stearate, and polyacrylates can be used individually or in combination of two or more.

[0058] In the polyester resin composition, the amount of the nucleating agent is preferably 0.05 to 2% by mass, more preferably 0.1 to 1.5% by mass, and even more preferably 0.3 to 1% by mass, based on the total amount of the polyester resin composition.

[0059] [Inorganic Filler] The polyester resin composition preferably contains an inorganic filler. A fibrous inorganic filler is preferred as the inorganic filler.

[0060] 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.). Typical fibrous inorganic fillers include glass fibers and carbon fibers, with glass fibers being preferred due to their availability and cost-effectiveness. The type of glass used as the raw material for glass fibers is not particularly limited, but for quality reasons, E-glass and corrosion-resistant glass containing zirconium in its composition are preferred.

[0061] The sizing agent for glass fibers may include urethane resin, acrylic resin, epoxy resin, unsaturated carboxylic acid compounds, coupling agents, lubricants, antistatic agents, etc. In particular, using glass fibers surface-treated with a sizing agent that includes unsaturated carboxylic acids and / or copolymers of anhydrous unsaturated carboxylic acids and unsaturated monomers, and epoxy resin as essential components, can improve hydrolysis resistance.

[0062] In the polyester resin composition, the inorganic filler is preferably 5 to 50% by mass, and more preferably 10 to 40% by mass, based on the total amount of the polyester resin composition.

[0063] [Other Components] The polyester resin composition may contain other components as needed. Examples of other components include, but are not limited to, antioxidants, weather stabilizers, molecular weight modifiers, ultraviolet absorbers, flame retardants, antistatic agents, lubricants, crystallization accelerators such as plasticizers, and colorants.

[0064] [Method for Manufacturing Polyester Resin Compositions] The method for manufacturing polyester resin compositions is not particularly limited. Polyester resin compositions can be manufactured by various methods known as methods for manufacturing thermoplastic resin compositions.

[0065] A suitable method for producing a polyester resin composition 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.

[0066] <Resin molded product> The resin molded product of this embodiment can be obtained using the polyester resin composition described above.

[0067] There are no particular limitations on the method for producing resin molded products using a polyester resin composition, and known methods can be employed. For example, the polyester resin composition can be put into an extruder, melt-kneaded to form pellets, and then these pellets can be put into an injection molding machine equipped with a predetermined mold and injected to produce the product.

[0068] The resin composition of this embodiment exhibits excellent mold release properties and superior productivity of molded resin products. Furthermore, molded resin products obtained using this resin composition exhibit excellent hydrolysis resistance and can be suitably used as molded products that are exposed to high temperature and high humidity environments for long periods of time, such as in automobiles, trains, and the aerospace industry. The molded resin products of this embodiment can be used in connectors, sensors, actuators, ECU housings, levers, switches, relays, and the like.

[0069] Embodiments of the present invention include, but are not limited to, the following embodiments. <1> A polyester resin composition comprising a polybutylene terephthalate resin, a recycled polyethylene terephthalate resin, a transesterification inhibitor, a carbodiimide compound, and an elastomer, wherein the amount of terminal hydroxyl groups of the polybutylene terephthalate resin is 30 to 70 mmol / kg with respect to the total amount of the polybutylene terephthalate resin and the recycled polyethylene terephthalate resin, the amount of the carbodiimide compound is 0.2 to 1.5% by mass with respect to the total amount of the polyester resin composition, and the amount of the elastomer is 3 to 15% by mass with respect to the total amount of the polyester resin composition. <2> The polyester resin composition according to <1>, wherein the sum of the amount of terminal hydroxyl groups of the polybutylene terephthalate resin and the recycled polyethylene terephthalate resin is 60 to 90 mmol / kg with respect to the total amount of the polybutylene terephthalate resin and the recycled polyethylene terephthalate resin. <3> The polyester resin composition according to <1> or <2>, wherein the transesterification inhibitor comprises a phosphorus compound containing a sodium atom or a calcium atom. <4> The polyester resin composition according to any one of <1> to <3>, further comprising a crystal nucleating agent. <5> The polyester resin composition according to any one of <1> to <4>, further comprising 5 to 50% by mass of an inorganic filler based on the total amount of the polyester resin composition. <6> A resin molded article obtained using the polyester resin composition according to any one of <1> to <5>.

[0070] The embodiment will be described in more detail below with reference to examples, but this embodiment is not limited to the following examples.

[0071] [Examples 1-11, Comparative Examples 1-7] The materials listed in Tables 1-2 were melt-kneaded and extruded in the ratios (mass%) shown in Tables 1-2 using a 30 mmφ twin-screw extruder (TEX30, manufactured by Japan Steel Works Ltd.) at a cylinder temperature of 260°C and a screw rotation speed of 130 rpm to obtain pellets consisting of the polyester resin compositions of Examples 1-11 and Comparative Examples 1-7. Details of each component shown in Tables 1-2 are shown below.

[0072] (1) PBT resin (A) (A-1): PBT resin: Manufactured by Polyplastics Co., Ltd., terminal hydroxyl group content 80 mmol / kg (A-2): PBT resin, manufactured by Polyplastics Co., Ltd., terminal hydroxyl group content 100 mmol / kg (A-3): PBT resin, manufactured by Polyplastics Co., Ltd., terminal hydroxyl group content 120 mmol / kg

[0073] (2) Recycled PET resin (B) (B-1): Recycled PET resin, Indorama Corporation "N1-100", terminal hydroxyl group content 40 mmol / kg

[0074] (4) Transesterification inhibitor (C) (C-1): Sodium dihydrogen phosphate, manufactured by Yoneyama Chemical Industry Co., Ltd.

[0075] (5) Carbodiimide (D) (D-1): Aromatic carbodiimide compound ("STABAXOL P100" manufactured by LANXESS K.K.) (D-2): Cyclic carbodiimide compound ("Carbodista TCC-NP" manufactured by Teijin Limited)

[0076] (6) Elastomers (E) (E-1): Ethylene-ethyl acrylate copolymer, manufactured by Nippon Unicar, "NUC-6570" (E-2): Ethylene-ethyl acrylate copolymer, manufactured by Nippon Unicar, "NUC-6220" (E-3): Core-shell elastomer, manufactured by Dow Chemical, "Paraloid EXL-2314"

[0077] (10) Nucleating agent (F) (F-1): Talc, "Talcan Powder PK-NN" manufactured by Hayashi Chemical Co., Ltd.

[0078] (8) Inorganic filler (G) (G-1): Glass fiber "ECS 03 T-127" manufactured by Nippon Electric Glass Co., Ltd.

[0079] (9) Lubricant (H) (H-1): Pentaerythritol stearate ester, manufactured by NOF Corporation, "Unistar H476"

[0080] (10) Antioxidant (I) (I-1): Hindered phenol antioxidant BASF "IRGANOX 1010"

[0081] In Tables 1 and 2, "PBT terminal hydroxyl group amount (moles / kg)" refers to the amount of terminal hydroxyl groups of PBT resin (A) relative to the total amount of PBT resin (A) and recycled PET resin (B) in the polyester resin composition (moles / kg). "PET terminal hydroxyl group amount (moles / kg)" refers to the amount of terminal hydroxyl groups of recycled PET resin (B) relative to the total amount of PBT resin (A) and recycled PET resin (B) in the polyester resin composition (moles / kg). "Total terminal hydroxyl group amount (moles / kg)" refers to the sum of the terminal hydroxyl groups of PBT resin (A) and recycled PET resin (B) relative to the total amount of PBT resin (A) and recycled PET resin (B) in the polyester resin composition (moles / kg). The number of terminal hydroxyl groups in the PBT resin (A) and the recycled PET resin (B) in the polyester resin composition were measured by NMR using a Bruker NMR spectrometer "AVANCE III 400".

[0082] <Evaluation Method>

[0083] (1) Cooling time (release properties) For the resin compositions in Tables 1 and 2, molded products of the shape shown in Figure 1 were formed using Toshiba Corporation's "EC40," and the minimum time required for release at a holding pressure of 70 MPa (cooling time (seconds)) was measured. Shorter cooling times indicate better release properties. The results (cooling time (seconds)) are shown in Tables 1 and 2. The molding conditions were as follows.

[0084] (Molding conditions) Cylinder temperature: 250°C Mold temperature: 60°C Injection speed: 20 mm / sec Injection and holding pressure: 5 seconds

[0085] Figure 1 is a schematic perspective view of a molded product used to evaluate the cooling time (release properties). In Figure 1, 1 is the molded product, 2 is the short side, 3 is the cylinder, 4 is the long side, and 5 is the ejector pin protrusion area. The molded product 1 has a thin T-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), and 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 central ejector pin protrusion area 5 on the other side of the long side 4.

[0086] (2) Hydrolysis Resistance Pellets prepared with the compositions shown in Tables 1 and 2 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 1A type tensile test specimens in accordance with ISO 3167. The tensile strength of the obtained test specimens was measured in accordance with ISO 527-1 and 527-2. Next, using a PCT treatment apparatus (high-accelerated life testing apparatus), the test specimens were exposed to 121°C and 100% RH, and the tensile strength was measured after 50 hours. The strength retention rate before and after moist heat treatment was calculated, and specimens that met the strength retention rate of 50% or more were classified as A, and those that did not were classified as B. The results are shown in Tables 1 and 2.

[0087]

[0088]

[0089] As shown in Table 1, Examples 1 to 11 showed excellent results in both cooling time (release properties) and hydrolysis resistance evaluation. On the other hand, as shown in Table 2, Comparative Example 1, which did not contain the transesterification inhibitor (C), Comparative Example 5, which had a large amount of elastomer (E), Comparative Example 6, which had a small amount of terminal hydroxyl groups in PBT resin (A) relative to the total amount of PBT resin (A) and PET resin (B), and Comparative Example 7, which had a large amount of terminal hydroxyl groups in PBT resin (A) relative to the total amount of PBT resin (A) and PET resin (B), tended to have longer cooling times. Comparative Examples 2 and 3, which did not contain carbodiimide (D) or contained a small amount of carbodiimide (D), Comparative Example 4, which did not contain elastomer (E), and Comparative Example 6, which contained a large amount of recycled PET resin (B), tended to have low hydrolysis resistance.

[0090] Although the present invention has been described with reference to several embodiments described above, the present invention is not limited to these embodiments. Various modifications can be made to the configuration and details of the present invention within the scope of the invention.

[0091] The disclosures of this application relate to the subject matter described in Japanese Patent Application No. 2024-190939, filed on 30 October 2024, all of which are incorporated herein by reference.

[0092] 1. Molded product 2. Short side 3. Cylinder 4. Long side 5. Eject pin protrusion area

Claims

1. A polyester resin composition comprising a polybutylene terephthalate resin, a recycled polyethylene terephthalate resin, a transesterification inhibitor, a carbodiimide compound, and an elastomer, wherein the amount of terminal hydroxyl groups of the polybutylene terephthalate resin is 30 to 70 mmol / kg relative to the total amount of the polybutylene terephthalate resin and the recycled polyethylene terephthalate resin, the amount of the carbodiimide compound is 0.2 to 1.5% by mass relative to the total amount of the polyester resin composition, and the amount of the elastomer is 3 to 15% by mass relative to the total amount of the polyester resin composition.

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

3. The polyester resin composition according to claim 1 or 2, wherein the transesterification inhibitor comprises a phosphorus-based compound containing a sodium atom or a calcium atom.

4. The polyester resin composition according to any one of claims 1 to 3, further comprising a crystal nucleating agent.

5. The polyester resin composition according to any one of claims 1 to 4, further comprising 5 to 50% by mass of an inorganic filler based on the total amount of the polyester resin composition.

6. A resin molded article obtained using the polyester resin composition described in any one of claims 1 to 5.

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