Alkali-resistant polyester resin composition and resin molded article

Abstract

The present invention provides a polyester resin composition with excellent alkali resistance and mold release properties. [Solution] An alkali-resistant polyester resin composition comprising a polybutylene terephthalate resin (A), a recycled polyethylene terephthalate resin (B), a transesterification inhibitor (C), a silicone compound (D), an elastomer (E), and an inorganic filler (F), wherein the amount of terminal hydroxyl groups of the polybutylene terephthalate resin (A) is 30 to 70 mmol / kg relative to the total amount of the polybutylene terephthalate resin (A) and the recycled polyethylene terephthalate resin (B), and the amount of the elastomer (E) is 8 to 17% by mass relative to the total amount of the alkali-resistant polyester resin composition.

Description

[Technical Field]

[0001] Embodiments of the present invention relate to alkali-resistant polyester resin compositions and resin molded articles. [Background technology]

[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 utilizing 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 has resulted in problems with moldability. For example, Patent Document 1 describes a resin composition containing PBT resin, PET resin, thermoplastic polyester elastomer, and an inorganic filler, wherein the inorganic filler consists of calcined kaolin and a non-fibrous inorganic filler, and exhibits excellent mold release properties.

[0005] Furthermore, when polybutylene terephthalate resin is used in applications such as automobiles, it tends to have low long-term durability against alkaline solutions. When used in parts that come into contact with alkaline cleaning agents or de-icing agents, exposure to these agents, which contain components such as sodium hypochlorite, sodium percarbonate, calcium chloride, and sodium hydroxide, while under strain, can cause environmental stress cracking, resulting in cracks in the molded product, which has been a problem. For example, Patent Document 2 describes that a composition containing PBT resin, PET resin as an amorphous alloy resin for improving dimensional accuracy, a filler for improving dimensional accuracy, and an aromatic polycarboxylic acid ester exhibits excellent alkali resistance. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2006-265331 [Patent Document 2] Japanese Patent Publication No. 2022-057306 [Overview of the project] [Problems that the invention aims to solve]

[0007] Embodiments of the present invention aim to provide an alkali-resistant polyester resin composition that exhibits excellent alkali resistance and mold release properties while being a blend of polybutylene terephthalate resin and recycled polyethylene terephthalate resin, and a resin molded article obtained using the same. [Means for solving the problem]

[0008] One embodiment of the present invention relates to an alkali-resistant polyester resin composition comprising a polybutylene terephthalate resin (A), a recycled polyethylene terephthalate resin (B), a transesterification inhibitor (C), a silicone compound (D), an elastomer (E), and an inorganic filler (F), wherein the amount of terminal hydroxyl groups of the polybutylene terephthalate resin (A) is 30 to 70 mmol / kg relative to the total amount of the polybutylene terephthalate resin (A) and the recycled polyethylene terephthalate resin (B), and the amount of the elastomer (E) is 8 to 17% by mass relative to the total amount of the alkali-resistant polyester resin composition. Another embodiment of the present invention relates to a resin molded article obtained using the alkali-resistant polyester resin composition described above. [Effects of the Invention]

[0009] According to embodiments of the present invention, it is possible to provide a polyester resin composition with excellent alkali resistance and mold release properties, and a resin molded article obtained using the same. [Brief explanation of the drawing]

[0010] [Figure 1] This is a schematic perspective view showing the molded product used to evaluate the release properties in the example. [Modes for carrying out the invention]

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

[0012] <Alkali-Resistant Polyester Resin Composition> The alkali-resistant polyester resin composition of the present embodiment contains a PBT resin (A), a recycled PET resin (B), a transesterification inhibitor (C), a silicone-based compound (D), an elastomer (E), and an inorganic filler (F). With respect to the total amount of the PBT resin (A) and the recycled PET resin (B), the amount of terminal hydroxyl groups of the PBT resin (A) is 30 to 70 mmol / kg, and the amount of the elastomer (E) is 8 to 17% by mass with respect to the total amount of the alkali-resistant polyester resin composition. It is an alkali-resistant polyester resin composition.

[0013] In a resin composition containing a PBT resin and a PET resin, an ester exchange reaction tends to occur easily between the PBT resin and the PET resin under high-temperature conditions such as during melting. If the transesterification reaction progresses too far, the melting point and crystallization temperature of the resin composition change, and temperature characteristics such as the heat deflection temperature, and physical properties such as tensile strength and elastic modulus decrease, and the expected physical properties may not be obtained. Also, if the crystallization temperature changes and crystallization becomes difficult, the shrinkage amount during injection molding may decrease, the rigidity may decrease due to a decrease in the solidification rate, deformation may occur during脱模 from the mold, or the productivity may decrease due to an increase in the molding cycle time. The same applies when the PET resin is changed to a recycled PET resin. The transesterification reaction is a reaction in which the main chain part is exchanged by the reaction of an ester group and a hydroxyl group, and it is affected by the hydroxyl group concentration. However, even if the total amount of hydroxyl groups of the resin in the resin composition is small, the脱模 property may not be improved.

[0014] The alkali-resistant polyester resin composition of the present embodiment contains a PBT resin (A), a recycled PET resin (B), a transesterification inhibitor (C), a silicone-based compound (D), an elastomer (E), and an inorganic filler (F). With respect to the total amount of the PBT resin (A) and the recycled PET resin (B), the amount of terminal hydroxyl groups of the PBT resin (A) is 30 to 70 mmol / kg, and the amount of the elastomer (E) is 8 to 17% by mass with respect to the total amount of the alkali-resistant polyester resin composition. The alkali-resistant polyester resin composition of the present embodiment is excellent in脱模 property and also excellent in alkali resistance.

[0015] [Polybutylene terephthalate resin (A)] PBT resin (A) contains at least terephthalic acid or its ester-forming derivative (C 1-6 The resin is obtained by polycondensation of a dicarboxylic acid component containing alkyl esters or acid halides (such as those of 1,4-butanediol) having at least 4 carbon atoms, or a glycol component containing an ester-forming derivative thereof (such as an acetylated compound). The PBT resin (A) 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), may be derived from either fossil resources or biomass resources. PBT resin (A) 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 (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 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. For example, the amount of terminal carboxyl groups in PBT resin (A) 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 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 release properties, the amount of terminal hydroxyl groups in 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. For example, the amount of terminal hydroxyl groups in PBT resin (A) 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 number of terminal hydroxyl groups in PBT resin (A) is a value measured by NMR. Similarly, the number of terminal hydroxyl groups in recycled PET resin (B), described later, is also a value measured by NMR. Furthermore, the number of terminal hydroxyl groups in PBT resin (A) and recycled PET resin (B) in alkali-resistant polyester resin compositions, described later, are also values ​​measured by NMR. For example, a Bruker AVANCE III 400 NMR spectrometer can be used.

[0019] The intrinsic viscosity (IV) of 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. 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 and a PBT resin with an intrinsic viscosity of 1.1 dL / g. The intrinsic viscosity (IV) of PBT resin (A) can be measured, for example, in o-chlorophenol at a temperature of 35°C.

[0020] In PBT resin (A), 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; C such as succinic acid, adipic acid, azelaic acid, and sebacic acid 4-16 alkanedicarboxylic acids of C; C such as cyclohexanedicarboxylic acid 5-10 cycloalkanedicarboxylic acids of C; ester-forming derivatives (C of these dicarboxylic acid components 1-6 alkyl ester derivatives, acid halides, etc.) can be mentioned. These dicarboxylic acid components can be used alone 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 alkanedicarboxylic acids are more preferred.

[0022] In the PBT resin (A), as glycol components (comonomer components) other than 1,4-butanediol and its ester-forming derivatives, for example, C such as ethylene glycol, propylene glycol, trimethylene glycol, 1,3-butylene glycol, hexamethylene glycol, neopentyl glycol, 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 of bisphenol A such as 2-molar adduct of ethylene oxide of bisphenol A and 3-molar adduct of propylene oxide of bisphenol A 2-4 alkylene oxide adducts; or ester-forming derivatives (acetylates, etc.) of these glycols can be mentioned. These glycol components can be used alone or in combination of two or more.

[0023] Among these glycol components, C such as ethylene glycol and trimethylene glycol 2-6Polyoxyalkylene glycols such as alkylene glycols and diethylene glycols, or alicyclic diols such as cyclohexanedimethanol are more preferred. In addition to the dicarboxylic acid and glycol components, other comonomer components that can be used include, for example, 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; and C21603 3-12 Lactones; ester-forming derivatives of these comonomer components (C 1-6 Examples include alkyl ester derivatives, acid halides, acetylated compounds, etc.

[0024] The polybutylene terephthalate copolymers obtained by copolymerizing the comonomer components described above can all be suitably used as PBT resin (A). Furthermore, a combination of homopolybutylene terephthalate polymer and polybutylene terephthalate copolymer may be used as PBT resin (A).

[0025] PBT resin (A) can be recycled from the market (material recycling). Alternatively, PBT resin produced by decomposing 1,4-butanediol and terephthalic acid from PBT resin waste to the monomer level (chemical recycling) and then polycondensing the resulting raw materials can also be used.

[0026] 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 alkali-resistant polyester resin composition. On the other hand, the amount of PBT resin (A) 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 alkali-resistant polyester resin composition. For example, the amount of PBT resin (A) is preferably 20 to 60% by mass, more preferably 25 to 50% by mass, and even more preferably 30 to 40% by mass, based on the total amount of the alkali-resistant polyester resin composition.

[0027] [Recycled polyethylene terephthalate resin (B)] Recycled PET resin (B) is terephthalic acid or its ester-forming derivative (C 1-6 This polyester resin is obtained by polycondensation of alkyl esters and acid halides (such as ethylene glycol) or its ester-forming derivatives (such as acetylated compounds) according to known methods, and can utilize market-recovered products such as PET bottles, PET fibers, and films.

[0028] The recycled 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, to the extent that it does not hinder the objectives of the present invention. The amount of repeating units other than terephthaloyl units and ethylenedioxy units contained in the recycled PET resin (B) is preferably less than 4 mol%, more preferably 3 mol% or less, and even more preferably 2 mol% or less, of the total repeating units of the polyethylene terephthalate resin.

[0029] Furthermore, recycled PET resin (B) may contain 4 mol% or more of the repeating units derived from the modified component mentioned above, out of the total repeating units. Because the inclusion of the modified component improves transparency and film-forming properties, it is used in bottle and film applications, and can be utilized by recovering products used in such applications. Note that in this specification, such polyethylene terephthalate resin may also be referred to as "modified PET resin."

[0030] The modified PET resin may contain other dicarboxylic acids of terephthalic acid or their ester-forming derivatives (C) to the extent that it does not impede the purpose 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 Cycloalkane dicarboxylic 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. 6-12 Alkane 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 impede the objectives of the present invention. In the modified polyethylene terephthalate resin composition, 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, and other C 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 C, such as a 2-mol ethylene oxide adduct of bisphenol A and a 3-mol propylene oxide adduct of bisphenol A. 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 one example. 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 (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 release properties, the amount of terminal hydroxyl groups in recycled 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. For example, the amount of terminal hydroxyl groups in recycled PET resin (B) 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 the recycled PET resin (B) 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 that has been chemically recycled 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 (B) may be used alone or in combination of two or more types.

[0039] The amount of recycled PET resin (B) 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 alkali-resistant polyester resin composition. On the other hand, the amount of recycled PET resin (B) is preferably 50% by mass or less, more preferably 45% by mass or less, and even more preferably 40% by mass or less, relative to the total amount of alkali-resistant polyester resin composition. For example, the amount of PET resin (B) is preferably 10 to 50% by mass, more preferably 20 to 45% by mass, and even more preferably 25 to 40% by mass, relative to the total amount of alkali-resistant polyester resin composition.

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

[0041] In alkali-resistant polyester resin compositions, the amount of terminal hydroxyl groups of PBT resin (A) relative to the total amount of PBT resin (A) and recycled 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 alkali-resistant polyester resin compositions, the amount of terminal hydroxyl groups of PBT resin (A) relative to the total amount of PBT resin (A) and recycled 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.

[0042] From the viewpoint of further improving mold release properties, in alkali-resistant polyester resin compositions, 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) 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 alkali-resistant polyester resin compositions, 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) 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 alkali-resistant polyester resin compositions, the sum of the terminal hydroxyl groups of PBT resin and recycled PET resin (B) 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] Since PET resin is easily hydrolyzed by alkaline compounds, resin compositions containing PET resin are presumed to have poor alkali resistance. However, molded products using an alkali-resistant polyester resin composition containing PBT resin (A) and recycled PET resin (B) are less prone to cracking when subjected to strain in an alkali-resistant environment. It is presumed that the recycled PET resin (B) selectively hydrolyzes before cracks occur on the molded surface, releasing the strain and thus making cracking less likely.

[0045] [Transesterification inhibitor (C)] From the viewpoint of suppressing transesterification reactions, alkali-resistant polyester resin compositions preferably contain a transesterification inhibitor (C). Examples of transesterification inhibitors (C) 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 form or a hydrated form. From the viewpoint of further improving mold release properties, the alkali-resistant polyester resin composition preferably contains a phosphorus-based 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.

[0046] In the alkali-resistant polyester resin composition, the transesterification inhibitor (C) 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 alkali-resistant polyester resin composition. For example, in an alkali-resistant polyester resin composition, the amount of phosphorus-based compounds 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, relative to the total amount of the alkali-resistant polyester resin composition.

[0047] [Silicone-based compounds (D)] The alkali-resistant polyester resin composition of this embodiment preferably contains a silicone compound (D) from the viewpoint of improving alkali resistance and mold release properties.

[0048] Preferred silicone compounds (D) include, but are not limited to, 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.

[0049] Alternatively, a cured silicone powder that has absorbed silicone oil (hereinafter sometimes referred to as "silicone oil-absorbing cured silicone powder") may be used. As the silicone oil-absorbing cured silicone powder, for example, one can be obtained by pre-mixing 0.5 to 80% by weight of silicone oil into finely powdered cured silicone, allowing it to absorb, and then powdering it by any method. As the silicone that absorbs silicone oil and forms a cured silicone powder, for example, conventionally known silicone rubber or silicone gel can be used.

[0050] 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 hydroxyl group, and n is an integer. R3SiO[R2SiO]nSiR3(1) In the above general formula (1), R is a substituted or unsubstituted monovalent hydrocarbon group or hydroxyl group. Examples of substituted or unsubstituted monovalent hydrocarbon groups include alkyl groups such as methyl, ethyl, and propyl groups; alkenyl groups such as vinyl and allyl groups; aralkyl groups such as cycloalkyl groups and β-phenylethyl groups; and 3,3,3-trifluoropropyl, 3-mercaptopropyl, 3-aminopropyl, and 3-glycidoxypropyl groups.

[0051] In this embodiment, the kinematic viscosity of the silicone compound (D) at 25°C is 1000 to 10000 cSt (10 to 100 cm² / s), preferably 2000 to 8000 cSt, and more preferably 3000 to 6000 cSt. When using the silicone oil absorption curing silicone powder mentioned above, the silicone oil to be absorbed should have a kinematic viscosity within the above range.

[0052] Silicone compounds may be used individually or in combination of two or more.

[0053] The content of silicone compound (D) is preferably 0.3 parts by mass or more and 2.0 parts by mass or less, more preferably 0.4 parts by mass or more and 1.5 parts by mass or less, and even more preferably 0.5 parts by mass or more and 1.0 part by mass or less, based on the total amount of the alkali-resistant polyester resin composition. When the content of silicone compound (D) is 0.3% by weight or more, the effects of improved alkali resistance and improved mold release properties are obtained, and when it is 2.0% by mass or less, problems such as measurement errors due to seepage from the molded product are less likely to occur.

[0054] [Elastomer (E)] In this embodiment, olefin-based elastomers and core-shell elastomers are preferred as the elastomer (E).

[0055] The amount of elastomer (E) added is 8 to 17% by mass of the total alkali-resistant polyester resin composition, preferably about 10 to 15% by mass. If the amount of elastomer (E) added is less than 5% by mass of the total alkali-resistant polyester resin composition, the alkali resistance improvement effect may not be obtained. From the viewpoint of improving alkali resistance, the amount of elastomer (E) added is preferably 8% by mass or more, and more preferably 10% by mass or more, of the total alkali-resistant polyester resin composition. From the viewpoint of improving mold release properties, the amount of elastomer (E) added is preferably 17% by mass or less, and more preferably 15% by mass or less, of the total alkali-resistant polyester resin composition.

[0056] 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. These olefin-based elastomers can be used individually or in combination of two or more.

[0057] Core-shell elastomers are polymers composed of a core layer made of a rubber component (soft component) and a shell layer made 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 less), more preferably -20°C or less (e.g., -180°C to -25°C), and particularly preferably -30°C or less (e.g., -150°C to -40°C).

[0058] 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-C12 alkyl ester of acrylic acid, such as butyl acrylate, and more preferably a C2-C6 alkyl ester of acrylic acid.

[0059] 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.

[0060] 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, methacrylate monomers, and acrylic acid 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, if necessary, by adding a graft cross-agent that reacts with the shell layer during polymerization of the core layer, thereby providing reactive groups to the core layer, and then forming the shell layer. When silicone rubber is used as the graft cross-agent, organosiloxanes having vinyl bonds or organosiloxanes having thiols are used, and acronoxysiloxane, methacryloxysiloxane, and vinylsiloxane are preferably used.

[0061] [Inorganic filler (F)] The alkali-resistant polyester resin composition preferably contains an inorganic filler (F). A fibrous inorganic filler is preferred as the inorganic filler (F).

[0062] 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. Metal fibers are effective in products requiring electromagnetic shielding, but when exposed to alkaline solutions such as calcium chloride or sodium chloride, residual solution and attached salts can absorb moisture from the air and act as electrolytes, causing oxidation through reaction between the metal and oxygen in the air, potentially generating rust or alkaline substances. Therefore, stainless steel fibers are preferred.

[0063] In the alkali-resistant polyester resin composition, the amount of inorganic filler (F) is preferably 5 to 50% by mass, more preferably 5 to 40% by mass, and even more preferably 10 to 30% by mass, based on the total amount of the alkali-resistant polyester resin composition.

[0064] [Crystal Nucleating Agent (G)] From the viewpoint of promoting resin crystallization, the alkali-resistant polyester resin composition preferably contains a crystal nucleating agent (G). The nucleating agent (G) may be an organic substance, an inorganic substance, or a combination thereof. As inorganic substances, for example, individual elements 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 can be used individually or in combination of two or more. As organic substances, for example, 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 crosslinked polymers can be used individually or in combination of two or more.

[0065] In the alkali-resistant polyester resin composition, the amount of the nucleating agent (G) 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 alkali-resistant polyester resin composition.

[0066] [Other ingredients] The alkali-resistant 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, antistatic agents, dyes, pigments, lubricants, crystallization accelerators such as plasticizers, flame retardants, flame retardant aids, and colorants.

[0067] [Method for producing alkali-resistant polyester resin composition] The method for producing alkali-resistant polyester resin compositions is not particularly limited. Alkali-resistant polyester resin compositions can be produced by various methods known as methods for producing thermoplastic resin compositions.

[0068] A suitable method for producing an alkali-resistant 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.

[0069] <Resin molded products> The resin molded product of this embodiment can be obtained using the alkali-resistant polyester resin composition described above.

[0070] There are no particular limitations on the method for producing resin molded products using alkali-resistant polyester resin compositions, and known methods can be employed. For example, the alkali-resistant 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.

[0071] 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 reduced post-shrinkage under high-temperature conditions and can be suitably used as molded products exposed to high-temperature and high-humidity environments for long periods, 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.

[0072] Embodiments of the present invention include, but are not limited to, the following embodiments. <1> An alkali-resistant polyester resin composition comprising polybutylene terephthalate resin (A), recycled polyethylene terephthalate resin (B), transesterification inhibitor (C), silicone compound (D), elastomer (E), and inorganic filler (F), With respect to the total amount of the polybutylene terephthalate resin (A) and the recycled polyethylene terephthalate resin (B), the amount of terminal hydroxyl groups in the polybutylene terephthalate resin (A) is 30 to 70 mmol / kg. An alkali-resistant polyester resin composition in which the amount of the elastomer (E) is 8 to 17% by mass relative to the total amount of the alkali-resistant polyester resin composition. <2> With respect to the total amount of the polybutylene terephthalate resin (A) and the recycled polyethylene terephthalate resin (B), the sum of the terminal hydroxyl groups of the polybutylene terephthalate resin (A) and the recycled polyethylene terephthalate resin (B) is 60 to 90 mmol / kg. <1> The alkali-resistant polyester resin composition described above. <3> The transesterification inhibitor (C) comprises a phosphorus compound containing a sodium atom or a calcium atom. <1> or <2> The alkali-resistant polyester resin composition described above. <4> Further containing a nucleating agent (G), <1> ~ <3> The alkali-resistant polyester resin composition according to any one of the above. <5> The amount of the inorganic filler (F) is 5 to 50% by mass relative to the total amount of the alkali-resistant polyester resin composition. <1> ~ <4> The alkali-resistant polyester resin composition according to any one of the above. <6> <1> ~ <5> A resin molded article obtained using the alkali-resistant polyester resin composition described in any one of the above. [Examples]

[0073] The embodiment will be described in more detail below with reference to examples, but this embodiment is not limited to the following examples.

[0074] [Examples 1-6, Comparative Examples 1-4] The materials listed in Tables 1-3 were melt-kneaded and extruded in the ratios (mass%) shown in Tables 1-3 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 alkali-resistant polyester resin compositions of Examples 1-9 and Comparative Examples 1-3. Details of each component shown in Table 1 are given below.

[0075] (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

[0076] (2) Recycled PET resin (B) (B-1): PET resin, Indorama N1-100, terminal hydroxyl group content 40 mmol / kg

[0077] (3) Transesterification inhibitor (C) (C-1): Sodium dihydrogen phosphate, manufactured by Yoneyama Chemical Industries, Ltd.

[0078] (4) Silicone compounds (D) (D-1): Silicone compound 1: Dimethylpolysiloxane with a kinematic viscosity of 5000 cSt at 25°C

[0079] (5) Elastomer (E) (E-1): Core-shell type elastomer, Dow Chemical's "Paraloid EXL-2311" (E-2): Ethylene-ethyl acrylate copolymer, manufactured by Nippon Unicar, "NUC-6570"

[0080] (3) Inorganic filler (F) (F-1): Glass fiber, manufactured by Nippon Electric Glass Co., Ltd., "ECS 03 T-127"

[0081] (5) Nucleating agent (G) (G-1): Boron nitride, manufactured by Mizushima Iron Alloy Co., Ltd.

[0082] In Table 1, "PBT terminal hydroxyl group amount (mmol / kg)" is the amount of terminal hydroxyl groups (mmol / kg) of PBT resin (A) relative to the total amount of PBT resin (A) and recycled PET resin (B) in the alkali-resistant polyester resin composition. "PET terminal hydroxyl group amount (mmol / kg)" is the amount of terminal hydroxyl groups (mmol / kg) of recycled PET resin (B) relative to the total amount of PBT resin (A) and recycled PET resin (B) in the alkali-resistant polyester resin composition. "Total terminal hydroxyl group amount (mmol / kg)" is the sum of the terminal hydroxyl groups of PBT resin (A) and PET resin (B) relative to the total amount of PBT resin (A) and recycled PET resin (B) in the alkali-resistant polyester resin composition. The number of terminal hydroxyl groups in the PBT resin (A) and the recycled PET resin (B) in the alkali-resistant polyester resin composition was measured by NMR using a Bruker AVANCE III 400 NMR spectrometer.

[0083] <Evaluation Method>

[0084] (1) Cooling time (release properties) For the resin compositions listed in Table 1, molded products with the shape shown in Figure 1 were produced using Toshiba Corporation's "EC40" resin, and the minimum time required for demolding (cooling time (seconds)) at a holding pressure of 70 MPa was measured. A shorter cooling time indicates superior demolding performance. The results (cooling time (seconds)) are shown in Table 1. The molding conditions are as follows:

[0085] (Molding conditions) Cylinder temperature: 250℃ Mold temperature: 60℃ Injection speed: 20mm / sec Injection and holding pressure: 5 seconds

[0086] 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.

[0087] (2) Alkali resistance The pellets obtained in each example and comparative example were used to conduct the following evaluation tests. Pellets prepared with the composition shown in Table 1 were dried at 140°C for 3 hours, then injection molded at a cylinder temperature of 260°C and a mold temperature of 80°C to create a flat plate-like molded piece with a thickness of 1 mm and a side length of 80 mm, with a weld area. Next, this molded piece was cut into strips 10 mm wide and 80 mm long, so that the weld area was approximately in the center of the longitudinal direction, to prepare test specimens. These test specimens were fixed in a jig in a bent state so that a bending strain of 1.0% was constantly applied to the weld area. In this state, the jig and specimens were immersed in a 10 mass% sodium hydroxide aqueous solution and left to stand at an ambient temperature of 23°C. Every 25 hours, the presence or absence of cracks in the test specimens was observed. Evaluation was performed using three test specimens for each example and comparative example pellet, and the time until cracks occurred in at least one of the three test specimens was confirmed. Table 1 shows the evaluation results 100 hours after the start of immersion. ○ means that no cracks were found in any of the three test specimens, and × means that cracks were found in at least one of the three test specimens. The results are shown in Table 1.

[0088] [Table 1]

[0089] As shown in the table, in Examples 1 to 6, which contain PBT resin (A), recycled PET resin (B), transesterification inhibitor (C), silicone compound (D), elastomer (E), and inorganic filler (F), and in which the amount of terminal hydroxyl groups of PBT resin (A) is 30 to 70 mmol / kg relative to the total amount of PBT resin (A) and recycled PET resin (B), and the amount of elastomer (E) is 8 to 17% by mass relative to the total amount of alkali-resistant polyester resin composition, excellent results were shown in both the cooling release time and the evaluation of alkali resistance. [Explanation of symbols]

[0090] 1 Molded product 2 Short side 3 cylinders 4 Long side 5. Eject pin protrusion area

Claims

1. An alkali-resistant polyester resin composition comprising polybutylene terephthalate resin (A), recycled polyethylene terephthalate resin (B), transesterification inhibitor (C), silicone compound (D), elastomer (E), and inorganic filler (F), With respect to the total amount of the polybutylene terephthalate resin (A) and the recycled polyethylene terephthalate resin (B), the amount of terminal hydroxyl groups of the polybutylene terephthalate resin (A) is 30 to 70 mmol / kg. An alkali-resistant polyester resin composition in which the amount of the elastomer (E) is 8 to 17% by mass relative to the total amount of the alkali-resistant polyester resin composition.

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

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

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

5. The alkali-resistant polyester resin composition according to claim 1 or 2, wherein the amount of the inorganic filler (F) is 5 to 50% by mass relative to the total amount of the alkali-resistant polyester resin composition.

6. A resin molded article obtained using the alkali-resistant polyester resin composition described in claim 1 or 2.

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