Thermoplastic polyester resin composition for foam molding, and foam molded article

Abstract

The present disclosure addresses the problem of providing a polyester resin composition suitable for mold expansion methods such as foam molding, particularly core-back foam injection molding. A thermoplastic polyester resin composition for foam molding according to the present disclosure contains a crystalline polyester (A1), a crystalline polyester (A2) other than the crystalline polyester (A1) and / or an amorphous polyester (B), and a glycidyl-group-containing styrene copolymer (C), and furthermore contains, as needed, an inorganic reinforcing material (D), wherein: in a total of 100 mass parts of (A1), (A2), (B), and (C), (A1) is 60 parts by mass or more, (A2) is 0-40 parts by mass, (B) is 0-30 parts by mass, (A2) and (B) are a total of 5 parts by mass or more, and (C) is 0.1-7 parts by mass; (D) is 0-100 parts by mass relative to a total of 100 mass parts of (A1), (A2), (B), and (C); and the thermoplastic polyester resin composition for foam molding satisfies formula (1).　Formula (1): Tm − Tc2 ≥ 30°C

Description

Thermoplastic polyester resin composition for foam molding, and foam molded product

[0001] The present invention relates to a thermoplastic polyester resin composition for foam molding, and an in-vehicle part obtained by foam molding the thermoplastic polyester resin composition.

[0002] Since the fuel efficiency of automobiles is improved by reducing the weight, weight reduction such as replacing metal parts with resin molded products has been promoted conventionally. For example, resin molded products are used for many in-vehicle parts such as exterior panels, engine-related parts, mechanism parts, door linings, dashboards, consoles, meter panels, monitors, and switches. Further weight reduction of these resin molded products is being studied. As a technique for realizing weight reduction of resin molded products, parts obtained by foam molding resin (foam molded products) are being studied. Since foam molding can create a bubble structure inside the resin and suppress the amount of resin used, the parts can be made lighter than non-foam molded products. Also, from the viewpoint of improving recyclability, foam molded products using a thermoplastic polyester resin composition (hereinafter referred to as a polyester resin composition) are being studied. For example, Patent Document 1 discloses a polyester resin composition suitable for foam molding and a foam molded product. In recent years, as a foam molded body with excellent appearance, a foam molded body having a sandwich structure with a non-foam skin layer on the surface and a foam layer inside has attracted attention.

[0003] Japanese Patent Application Laid-Open No. 2005-60622

[0004] The foam molded body having a sandwich structure is formed by a mold expansion method such as core-back injection foam molding, but a polyester resin composition suitable for core-back injection foam molding has not been provided yet. For example, problems occur in foam moldability such as the injected polyester resin composition not being injected to the end of the mold or foam defects occurring, and problems also occur in appearance such as swelling on the surface of the foam molded body or appearance defects such as silver, flash, and swarm marks on the surface.

[0005] The present invention has been made in view of the above problems, and its purpose is to provide a polyester resin composition suitable for foam molding, particularly mold expansion methods such as core-back injection foam molding. Another object of the present invention is to provide a foam molded product with excellent appearance.

[0006] The polyester resin composition of the present invention that can solve the above problems has the following composition: [1] A thermoplastic polyester resin composition comprising a crystalline polyester (A1), a crystalline polyester other than the crystalline polyester (A2), and / or an amorphous polyester (B), a glycidyl group-containing styrene copolymer (C), and further optionally an inorganic reinforcing material (D), wherein in a total of 100 parts by mass of the crystalline polyester (A1), the crystalline polyester (A2), the amorphous polyester (B), and the glycidyl group-containing styrene copolymer (C), the crystalline polyester (A1) is 60 parts by mass or more, the crystalline polyester (A2) is 0 to 40 parts by mass, the amorphous polyester (B) is 0 to 30 parts by mass, and the total amount of the crystalline polyester (A2) and the amorphous polyester (B) is 5 parts by mass or more, and the glycidyl group-containing styrene copolymer (C) is 0.1 to 7 parts by mass, A thermoplastic polyester resin composition for foam molding, comprising 0 to 100 parts by mass of the inorganic reinforcing material (D) per 100 parts by mass of the total of the crystalline polyester (A1), the crystalline polyester (A2), the amorphous polyester (B), and the glycidyl group-containing styrene copolymer (C), and satisfying the following formula (1): Tm - Tc2 ≥ 30°C (1) where Tm (°C): melting point of the thermoplastic polyester resin composition determined by differential scanning calorimeter (DSC) Tc2 (°C): cooling crystallization temperature of the thermoplastic polyester resin composition determined by differential scanning calorimeter (DSC) [2] The thermoplastic polyester resin composition for foam molding according to [1], wherein the crystalline polyester (A1) mainly comprises terephthalic acid or a derivative thereof as a polycarboxylic acid component, and the polyhydric alcohol component mainly comprises a linear aliphatic polyhydric alcohol having 4 or fewer carbon atoms, or a polyhydric alcohol having 6 or more carbon atoms with an alicyclic skeleton. [3] The thermoplastic polyester resin composition for foam molding according to [1] or [2], wherein the crystalline polyester (A2) is polyethylene terephthalate or polybutylene terephthalate, which may be copolymerized.[4] The amorphous polyester (B) is copolymerized polyethylene terephthalate, as described in any of [1] to [3]. [5] The crystalline polyester (A1) is a copolymerized polyester obtained by copolymerizing dimerol as a diol component, as described in any of [1] to [4]. [6] The crystalline polyester (A1) is polybutylene terephthalate, as described in any of [1] to [5]. [7] The crystalline polyester (A1) is a copolymer of polybutylene terephthalate or polycyclohexylene dimethylene terephthalate and dimerol, as described in any of [1] to [5]. [8] The crystalline polyester (A2) is a copolymerized polyester obtained by copolymerizing an aromatic dicarboxylic acid other than terephthalic acid as a dicarboxylic acid component, as described in any of [1] to [7]. [9] The thermoplastic polyester resin composition for foam molding according to any one of [1] to [8], wherein the crystalline polyester (A2) is a copolymer of polybutylene terephthalate and isophthalic acid.

[10] The thermoplastic polyester resin composition for foam molding according to any one of [1] to [9], wherein the amorphous polyester (B) is copolymerized polyethylene terephthalate obtained by copolymerizing an aliphatic diol having a branched chain structure as a diol component.

[11] The thermoplastic polyester resin composition for foam molding according to any one of [1] to

[10] , wherein the amorphous polyester (B) is a copolymer of polyethylene terephthalate and neopentyl glycol.

[12] The thermoplastic polyester resin composition for foam molding according to any one of [1] to

[11] , wherein the glycidyl group-containing styrene copolymer (C) is a copolymer containing a vinyl aromatic monomer and a glycidyl alkyl (meth)acrylate as constituent units.

[13] The thermoplastic polyester resin composition for foam molding according to

[12] , wherein the vinyl aromatic monomer is styrene and the glycidyl alkyl (meth)acrylate is glycidyl acrylate.

[14] A foamed molded article obtained by molding a thermoplastic polyester resin composition for foam molding according to any one of [1] to

[13] , wherein the foamed molded article has non-foamed skin layers on both sides of the foamed layer.

[15] An in-vehicle part obtained by molding a thermoplastic polyester resin composition for foam molding according to any one of [1] to

[13] .

[0007] The polyester resin composition of the present invention exhibits excellent foam moldability and is suitable for foam molding, particularly core-back injection foam molding. Furthermore, using the polyester resin composition of the present invention makes it possible to provide foam molded products with excellent appearance.

[0008] Figure 1 is a schematic diagram illustrating an example of a method for producing a foamed molded article obtained by foaming the thermoplastic polyester resin composition of the present invention. Figure 2 is a photograph showing the foamed state of a cross-section of the foamed molded article of the example.

[0009] The thermoplastic polyester resin composition of the present disclosure suitable for foam molding (hereinafter referred to as the polyester resin composition) contains predetermined amounts of a crystalline polyester (A1), a crystalline polyester (A2) different from the crystalline polyester (A1) and / or an amorphous polyester (B), and a glycidyl group-containing styrene copolymer (C), and may optionally contain a predetermined amount of an inorganic reinforcing material (D). Furthermore, the polyester resin composition has a melting point Tm (°C) and a cooling crystallization temperature Tc2 (°C) (sometimes referred to as the crystallization temperature) that satisfies the following formula (1): Tm - Tc2 ≥ 30°C (1) A foamed molded article having a sandwich structure with a non-foamed skin layer on the surface and a foamed layer inside (hereinafter referred to as the foamed molded article) is formed by a mold expansion method such as core-back injection foam molding, for example. In order to achieve good foam moldability and appearance, it is necessary to appropriately adjust not only the composition of the polyester resin composition but also the melting point Tm (°C) and crystallization temperature Tc2 (°C) of the polyester resin composition, as described below.

[0010] In this disclosure, foam moldability refers to the ability to fill a mold and the foamed state, and in preferred embodiments, it may also include the ability to conform to the shape of the foamed portion and the ability to release it from the mold. Appearance refers to the absence of blistering, silvering, flashing, and swirl marks on the surface of the foamed molded product. In particular, if the foamed molded product contains an inorganic reinforcing material, it is preferable that the surface of the foamed molded product is free from silvering, flashing, swirl marks, and lifting of the inorganic reinforcing material.

[0011] The polyester resin composition of this disclosure contains two or more polyesters. The two or more polyesters consist of a crystalline polyester (A1) as the main component (60 parts by mass or more), a crystalline polyester other than crystalline polyester (A2), and / or amorphous polyester (B) as minor components. This allows the crystallization rate of the fast-crystallizing crystalline polyester (A1) to be reduced by the crystalline polyester (A2) and / or amorphous polyester (B), thereby controlling the crystallization rate to satisfy formula (1) above, and improving foam moldability and appearance. Even when the crystallization rate of the slow-crystallizing crystalline polyester (A1) is increased by the crystalline polyester (A2) and / or amorphous polyester (B) to control the crystallization rate to satisfy formula (1) above, foam moldability and appearance can be improved. In this disclosure, "crystalline polyester other than crystalline polyester (A2)" means that the composition of crystalline polyester (A1) and crystalline polyester (A2) are different. The two types of crystalline polyester may be such that one with a higher content is designated as crystalline polyester (A1) (60 parts by mass or more), and the other with a lower content is designated as crystalline polyester (A2). In the preferred embodiment of this disclosure, crystalline polyester (A1) has a melting point of, for example, preferably 150°C or higher, more preferably 160°C or higher. Hereinafter, unless otherwise specified, crystalline polyester (A1) and crystalline polyester (A2) will be collectively referred to as "crystalline polyester (A)".

[0012] In this disclosure, crystalline polyester (A) means a material that exhibits a clear endothermic peak temperature in melting point measurements using a differential scanning calorimeter, as shown in the examples, and amorphous polyester (B) means a material that does not exhibit a clear endothermic peak temperature in the same melting point measurements.

[0013] The polyester resin compositions of this disclosure are described below. [Crystalline polyester (A1)] Crystalline polyester (A1) has a chemical structure obtained by polycondensation of a polycarboxylic acid component and a polyhydric alcohol component. The polycarboxylic acid component includes a dicarboxylic acid component, a tricarboxylic acid component which is a trivalent polycarboxylic acid, and a polycarboxylic acid component with tetravalent or higher valencies. The polyhydric alcohol component includes a diol component and a polyhydric alcohol component with trivalent or higher valencies. Furthermore, the various polycarboxylic acids exemplified below include not only the polycarboxylic acid itself, but also esters of the polycarboxylic acid and polycarboxylic acid anhydrides. Preferably, it has a chemical structure obtained by polycondensation of a dicarboxylic acid component and a diol component.

[0014] The dicarboxylic acid component and the diol component each consist of one or more selected components. The dicarboxylic acid component constituting the crystalline polyester (A1) is not particularly limited, but the dicarboxylic acids or their esters and dicarboxylic acid anhydrides listed below can be used. Specifically, examples of dicarboxylic acids include aliphatic dicarboxylic acids, alicyclic dicarboxylic acids, and aromatic dicarboxylic acids. Examples of aliphatic dicarboxylic acids include adipic acid, sebacic acid, dimer acid, fumaric acid, maleic acid, and succinic acid. Examples of alicyclic dicarboxylic acids include 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, tetrahydrophthalic acid, hexahydrophthalic acid, and methyltetrahydrophthalic acid. Examples of aromatic dicarboxylic acids include terephthalic acid, isophthalic acid, orthophthalic acid, naphthalenedicarboxylic acid, 2,5-frandicarboxylic acid, 5-sodium sulfodimethylisophthalic acid and their esters and acid anhydrides.

[0015] In preferred embodiments of this disclosure, the dicarboxylic acid component is preferably an aliphatic dicarboxylic acid or an aromatic dicarboxylic acid, more preferably at least an aromatic dicarboxylic acid, and even more preferably an aromatic dicarboxylic acid. Preferred aromatic dicarboxylic acids include terephthalic acid, isophthalic acid, orthophthalic acid, naphthalenedicarboxylic acid, and 2,5-franzicarboxylic acid, more preferably terephthalic acid, isophthalic acid, orthophthalic acid, and 2,5-franzicarboxylic acid, and even more preferably terephthalic acid and isophthalic acid. When an aromatic dicarboxylic acid is included, the aromatic dicarboxylic acid component is preferably 50 mol% or more, more preferably 70 mol% or more, even more preferably 80 mol% or more, particularly preferably 90 mol% or more, and may be 100 mol% in 100 mol% of the dicarboxylic acid component constituting polyester (A1). Terephthalic acid and isophthalic acid may be used alone or in combination as aromatic dicarboxylic acids. Alternatively, terephthalic acid and / or isophthalic acid may be used in combination with other dicarboxylic acids. For example, when terephthalic acid and isophthalic acid are used in combination, the content ratio (terephthalic acid:isophthalic acid) is preferably 5:95 to 95:5, more preferably 20:80 to 80:20, even more preferably 30:70 to 70:30, and particularly preferably 40:60 to 60:40, on a molar basis. When terephthalic acid and isophthalic acid are used in combination, the melting point of the polyester resin composition is lowered, and improved fluidity can be expected. When terephthalic acid (and its derivatives) is used in combination with other dicarboxylic acids, considering the improvement of crystallinity, the amount of terephthalic acid in 100 mol% of the dicarboxylic acid component constituting the crystalline polyester (A1) is preferably 50 mol% or more, more preferably 70 mol% or more, even more preferably 80 mol% or more, even more preferably 90 mol% or more, and particularly preferably 95 mol% or more.

[0016] Examples of diol components constituting the crystalline polyester (A1) include aliphatic diols, alicyclic diols, and bisphenol skeleton-containing monomers. The aliphatic diol may be either a linear or branched aliphatic diol, but a linear aliphatic diol is preferred when considering improved crystallinity. Examples of aliphatic diols include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2-methyl-1,3-propanediol, neopentyl glycol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 2-methyl-1,3-hexanediol, 2-methyl-2-ethyl-1,3-propanediol, and 2,2-diethyl-1,3-propanediol. Examples include 2-ethyl-2-n-propyl-1,3-propanediol, 2,2-di-n-propyl-1,3-propanediol, 2-n-butyl-2-ethyl-1,3-propanediol, 2,2-di-n-butyl-1,3-propanediol, 2,4-diethyl-1,5-pentanediol, 2-ethyl-1,3-hexanediol, dimer diol, diethylene glycol, triethylene glycol, dipropylene glycol, polyethylene glycol, polytetramethylene glycol, and polypropylene glycol. Among these, linear aliphatic diols having 2 to 9 carbon atoms, such as ethylene glycol, diethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, and 1,9-nonanediol, are preferred; more preferably linear aliphatic diols having 4 or fewer carbon atoms, such as ethylene glycol, diethylene glycol, 1,3-propanediol, and 1,4-butanediol, are preferred; and even more preferably ethylene glycol and 1,4-butanediol.

[0017] Alicyclic diols include polyhydric alcohols with 6 or more carbon atoms having an alicyclic skeleton, such as 1,4-cyclohexanedimethanol, tricyclodecanedimethanol, and dimergol. Of these, 1,4-cyclohexanedimethanol and dimergol are preferred. Examples of bisphenol skeleton-containing monomers include bisphenol A, bisphenol B, bisphenol E, bisphenol F, bisphenol AP, bisphenol BP, bisphenol P, bisphenol PH, bisphenol S, bisphenol Z, 4,4'-dihydroxybenzophenone, bisphenol fluorene and their hydrogenated products, and glycols such as ethylene oxide adducts and propylene oxide adducts obtained by adding 1 to several moles of ethylene oxide or propylene oxide to the hydroxyl group of bisphenols.

[0018] As the diol, aliphatic diols and alicyclic diols are preferred. When aliphatic diols and alicyclic diols are included, the diol component constituting the crystalline polyester (A1) is preferably 50 mol% or more, more preferably 70 mol% or more, even more preferably 80 mol% or more, and even more preferably 90 mol% or more, and may be 100 mol%.

[0019] Examples of crystalline polyester (A1) include polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT), polybutylene terephthalate (PBT), polycyclohexylenedimethylene terephthalate (PCT), polybutylene isophthalate (PBI), polycyclohexanedimethylene isophthalate (PCHT), polybutylene orthophthalate (PBO), polyethylene naphthalate (PEN), and polybutylene naphthalate (PBN), with polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polycyclohexylenedimethylene terephthalate (PCT) being preferred.

[0020] The crystalline polyester (A1) may be a homopolymer or a copolymer. The type and amount of copolymer components can be appropriately selected within a range that does not inhibit crystallinity. Examples of copolymer components include aromatic dicarboxylic acids such as isophthalic acid, orthophthalic acid, 2,6-naphthalenedicarboxylic acid, and 4,4'-diphenyldicarbon; aliphatic dicarboxylic acids such as succinic acid, adipic acid, azelaic acid, and sebacic acid; alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, and 4-methyl-1,2-cyclohexanedicarboxylic acid; trivalent aromatic carboxylic acids such as trimellitic acid, trimesic acid, and trimellitic anhydride (TMA); trivalent aliphatic carboxylic acids such as citric acid and citric anhydride; and polycarboxylic acids such as trivalent alicyclic tricarboxylic acids such as 1,2,4-cyclohexanetricarboxylic acid, 1,3,5-cyclohexanetricarboxylic acid, and cyclohexane-1,2,4-tricarboxylic acid-1,2-anhydride. These copolymerization components may be used individually or in combination of two or more. The copolymerization ratio of the copolymerization components (polycarboxylic acids) is preferably 5 mol% or less, more preferably 2 mol% or less, even more preferably 1 mol% or less, and may even be 0 mol%, when the total polycarboxylic acid components of the crystalline polyester (A1) are taken as 100 mol%.

[0021] Examples of copolymer components include polyhydric alcohols such as branched aliphatic glycols or alicyclic glycols, including 1,2-propanediol, 1,2-butanediol, 1,3-butanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, dipropylene glycol, 2,2,4-trimethyl-1,3-pentanediol, cyclohexanedimethanol, tricyclodecanedimethanol, neopentyl glycol hydroxypivalate, 2-methyloctanediol, 2-butyl-2-ethyl-1,3-propanediol, and dimergol. The number of carbon atoms in dimergol is not particularly limited, but those with 20 to 48 carbon atoms are preferred. The copolymerization ratio of the copolymerization component (polyhydric alcohol) is preferably 40 mol% or less, more preferably 30 mol% or less, even more preferably 20 mol% or less, even more preferably 10 mol% or less, particularly preferably 5 mol% or less, and may even be 0 mol%, when the total polyhydric alcohol component of the crystalline polyester (A1) is taken as 100 mol%. Of the above copolymerization components, dimer ol is preferred, and copolymerization with dimer ol lowers the glass transition temperature of the crystalline polyester (A1), which is expected to improve fluidity. Of the total polyhydric alcohol component at 100 mol%, dimer ol is preferably 5 to 35 mol%, more preferably 10 to 30 mol%. If the amount of dimer ol is too little, a sufficient fluidity improvement effect cannot be obtained, and if it is too much, the crystallinity of the crystalline polyester (A1) may decrease. For example, the crystalline polyester (A1) may be a copolymer of polybutylene terephthalate (PBT) and dimer ol, or a copolymer of polycyclohexylene dimethylene terephthalate (PCT) and dimer ol.

[0022] Crystalline polyester (A2) Crystalline polyester (A2) only needs to be different from crystalline polyester (A1), and may be either a homopolymer or a copolymer. The components of crystalline polyester (A2) are exemplified as those of crystalline polyester (A1), and can be selected from the above range. It is desirable that crystalline polyester (A2) can be adjusted so that the difference between the melting point Tm (°C) and the crystallization temperature Tc2 (°C) of the polyester resin composition satisfies formula (1) above. Specific examples of crystalline polyester (A2) are the same as those of crystalline (A1). In preferred embodiments of this disclosure, crystalline polyester (A2) may be polyethylene terephthalate or polybutylene terephthalate, which may be copolymers. It may also be a copolymer of aromatic dicarboxylic acid other than terephthalic acid, for example, a copolymer of isophthalic acid and polyethylene terephthalate (PET), or a copolymer of isophthalic acid and polybutylene terephthalate (PBT).

[0023] Amorphous polyester (B) Amorphous polyester (B) may be a homopolymer or a copolymer as long as it is amorphous, but it is preferably a copolymer. Amorphous copolymer polyester (B) is obtained by copolymerizing copolymer units with the same ester units as the main ester units in crystalline polyester (A1) as the main or secondary units. The copolymer units are selected from the copolymer units in an amount necessary to exhibit amorphousness.

[0024] In preferred embodiments of this disclosure, the amorphous polyester (B) is preferably a polyester mainly composed of terephthalic acid and ethylene glycol. The main components are defined as terephthalic acid and ethylene glycol, with total dicarboxylic acid and total diol components each accounting for 100 mol%, preferably 50 mol% or more, more preferably 60 mol% or more, and even more preferably 70 mol% or more. The amorphous polyester (B) mainly composed of terephthalic acid and ethylene glycol can have one or more of the above-mentioned polycarboxylic acids and polyhydric alcohols selected as copolymerization components. When a polycarboxylic acid is included as a copolymerization component, isophthalic acid is preferred, and the copolymer may contain 5 to 50 mol% of isophthalic acid, more preferably 10 to 50 mol%, of 100 mol% of the total polycarboxylic acid component. Other polycarboxylic acids may also be copolymerized. When a polyhydric alcohol is included as a copolymerization component, it is preferably an aliphatic diol or alicyclic diol, and the aliphatic diol may have a linear or branched structure. Specifically, one or more diols selected from neopentyl glycol, diethylene glycol, 1,4-cyclohexanedimethanol, 2-methyl-1,3-propanediol, and 1,3-propanediol are preferred (sometimes referred to as preferred diols), and the polyhydric alcohol component may contain, preferably 5 to 50 mol%, more preferably 10 to 50 mol%, of the above preferred diols in 100 mol of total polyhydric alcohol components. Polyhydric alcohols other than the above preferred diols may also be copolymerized. In preferred embodiments of this disclosure, the amorphous polyester (B) is a copolymer of neopentyl glycol and polyethylene terephthalate (PET); a copolymer of neopentyl glycol, isophthalic acid (copolymer component), and polyethylene terephthalate (PET); a copolymer of diethylene glycol and polyethylene terephthalate (PET); a copolymer of isophthalic acid, diethylene glycol (copolymer component), and polyethylene terephthalate (PET); and various copolymerized polyethylene terephthalates such as a copolymer of 1,4-cyclohexanedimethanol and polyethylene terephthalate (PET).

[0025] The acid value of the crystalline polyester (A) and / or amorphous polyester (B) is not particularly limited, but is preferably 1 to 400 eq / ton, more preferably 2 to 300 eq / ton, and even more preferably 3 to 200 eq / ton, taking productivity and other factors into consideration.

[0026] The number-average molecular weight (Mn) of the crystalline polyester (A) and / or amorphous polyester (B) is preferably 1,000 to 100,000, more preferably 2,000 to 90,000, and even more preferably 3,000 to 80,000.

[0027] The weight-average molecular weight (Mw) of the crystalline polyester (A) and / or amorphous polyester (B) is preferably 2,000 to 300,000, more preferably 3,000 to 200,000, even more preferably 4,000 to 150,000, and even more preferably 5,000 to 100,000.

[0028] The molecular weight distribution (Mw / Mn) of the crystalline polyester (A) and / or amorphous polyester (B) is preferably 1.0 to 7.0, more preferably 1.1 to 6.0, and even more preferably 1.2 to 5.0.

[0029] The glass transition temperature (Tg) of the crystalline polyester (A) and / or amorphous polyester (B) is preferably -100 to 150°C, more preferably -80 to 120°C, even more preferably -50 to 100°C, and particularly preferably 0 to 90°C.

[0030] The melting point of crystalline polyester (A) is preferably 130 to 320°C, more preferably 140 to 300°C, and even more preferably 150 to 290°C. If it is too low, the heat resistance may decrease. If it is too high, it may require high heat during filling, which may accelerate thermal aging.

[0031] The reduced viscosity (ηsp / c) of the crystalline polyester (A) and / or amorphous polyester (B) is preferably 0.50 to 4.0 dl / g, more preferably 0.55 to 3.5 dl / g, and even more preferably 0.60 to 3.0 dl / g.

[0032] The method for producing crystalline polyester (A) and amorphous polyester (B) can be any method capable of producing a polycondensate of a polycarboxylic acid component and a polyhydric alcohol component, and methods produced by commonly known methods can be used. For example, the polycarboxylic acid component and the polyhydric alcohol component can be produced by known polymerization methods such as transesterification or esterification. The polycarboxylic acid component and polyhydric alcohol component can be those mentioned above as appropriate. The production conditions such as catalyst, stabilizer, atmosphere, and temperature are not particularly limited, and various known conditions can be adopted. For example, the desired polyester resin can be obtained by esterifying the polycarboxylic acid component and the polyhydric alcohol component at 150 to 250°C, followed by polycondensation at 230 to 300°C under reduced pressure. Alternatively, the desired polyester resin can be obtained by transesterifying at 150 to 250°C, followed by polycondensation at 230 to 300°C under reduced pressure.

[0033] The content of crystalline polyester (A1), crystalline polyester (A2), and amorphous polyester (B) is as follows per 100 parts by mass of the total of crystalline polyester (A1), crystalline polyester (A2), amorphous polyester (B), and glycidyl group-containing styrene copolymer (C) (hereinafter referred to as the total polyester resin composition).

[0034] The content of crystalline polyester (A1) is 60 parts by mass or more out of 100 parts by mass of the total of crystalline polyester (A1), crystalline polyester (A2), amorphous polyester (B), and glycidyl group-containing styrene copolymer (C). In order to ensure foam moldability suitable for foam molding, particularly injection molding, of the polyester resin composition, it is necessary to have crystalline polyester (A1) as the main component, i.e., 60 parts by mass or more. The amount of crystalline polyester (A1) is preferably 65 to 98 parts by mass, more preferably 70 to 95 parts by mass, and even more preferably 70 to 90 parts by mass.

[0035] In a total of 100 parts by mass of crystalline polyester (A1), crystalline polyester (A2), amorphous polyester (B), and glycidyl group-containing styrene copolymer (C), the content of crystalline polyester (A2) is 0 to 40 parts by mass, the content of amorphous polyester (B) is 0 to 30 parts by mass, and the total amount of crystalline polyester (A2) and amorphous polyester (B) is 5 parts by mass or more. 0 parts by mass means not included, and the lower limit for inclusion is greater than 0 parts by mass (i.e., not including 0 parts by mass). The crystallization rate can be controlled by reducing the crystallization rate of the rapidly crystallizing crystalline polyester (A1) using crystalline polyester (A2) and / or amorphous polyester (B). That is, blending crystalline polyester (A2) and / or amorphous polyester (B) adjusts the melting point Tm (°C) and crystallization temperature Tc2 (°C) of the polyester resin composition, and as a result, foaming defects and appearance defects can be improved. On the other hand, when using a crystalline polyester (A1) with a slow crystallization rate, it is also possible to control the crystallization rate with a crystalline polyester (A2) with a fast crystallization rate, thereby adjusting the melting point Tm (°C) and crystallization temperature Tc2 (°C) of the polyester resin composition, and as a result, foaming defects and appearance defects can be improved. Either the crystalline polyester (A2) or the amorphous polyester (B) may be used, or they may be used in combination. It is preferable to select the crystalline polyester (A2) and the amorphous polyester (B) so as to appropriately lower or raise the crystallization temperature Tc2 (°C) of the crystalline polyester (A1) within the range of formula (1).

[0036] The content of crystalline polyester (A2) is 0 to 40 parts by mass, preferably 5 to 35 parts by mass, more preferably 10 to 30 parts by mass, and even more preferably 15 to 25 parts by mass. The content of amorphous polyester (B) is 0 to 30 parts by mass, preferably 3 to 28 parts by mass, more preferably 5 to 25 parts by mass, and even more preferably 10 to 20 parts by mass. The total amount of crystalline polyester (A2) and amorphous polyester (B) is 5 parts by mass or more, preferably 8 parts by mass or more, more preferably 10 parts by mass or more, and even more preferably 15 parts by mass or more, out of 100 parts by mass of the total of crystalline polyester (A1), crystalline polyester (A2), amorphous polyester (B), and glycidyl group-containing styrene copolymer (C).

[0037] Equation (1): Tm - Tc2 ≥ 30°C The melting point Tm (°C) and crystallization temperature Tc2 (°C) are determined by measuring the thermal properties of the polyester resin composition with a differential scanning calorimeter (DSC) and based on a graph (DSC curve) showing the relationship between temperature and heat flow. Specifically, the peak that appears when the polyester resin composition melts during the heating process is defined as the melting point Tm (°C), and the peak that appears when crystallization begins during the cooling process of the molten polyester resin composition is defined as the crystallization temperature Tc2 (°C). If multiple peaks are observed in the DSC curve, the peak with the largest area is adopted. The specific measurement conditions are as shown in the examples. If the difference between the melting point Tm (°C) and crystallization temperature Tc2 (°C) of the polyester resin composition is small, the molten polyester resin composition will solidify quickly after being filled into the mold, causing foaming defects and appearance defects. In addition, if an inorganic reinforcing material (D) is included, solidification defects such as glass fibers floating on the surface or cracking may occur. If the difference between the melting point Tm (°C) and the crystallization temperature Tc2 (°C) (Tm - Tc2) is 30°C or more, a foamed molded article with good foam moldability and appearance can be obtained. In one embodiment, if the difference between the melting point Tm (°C) and the crystallization temperature Tc2 (°C) becomes too wide, the surface may swell due to poor solidification during foaming, which is undesirable. In addition, deformation may occur when demolding from the mold, or the cooling time in the mold may become significantly longer, resulting in reduced productivity. The difference between the melting point Tm (°C) and the crystallization temperature Tc2 (°C) is 30°C or more, preferably 31°C to 70°C, more preferably 33°C to 60°C, and even more preferably 35°C to 50°C. In particular, when the content of amorphous polyester (B) is high, or when crystalline polyester (A2) that promotes crystallization is not included, it is desirable to adjust the difference (Tm - Tc2) to be relatively low even within this preferred range from the viewpoint of preventing surface swelling due to delayed solidification. The composition and content of crystalline polyester (A1), crystalline polyester (A2), and amorphous polyester (B) should be adjusted so that the relationship between the melting point Tm (°C) and the crystallization temperature Tc2 (°C), as determined by a differential scanning calorimeter (DSC), satisfies the above formula (1).

[0038] Glycidyl group-containing styrene copolymer (C) Glycidyl group-containing styrene copolymer (C) is an additive that increases the molecular weight and thus the melt extension viscosity. In mold expansion methods such as core-back injection foam molding, high fluidity, i.e., low shear viscosity is desired during filling, but if the fluidity is low and there is not a certain degree of viscosity during foaming, foaming failure will occur, or the foam cells will become coarse and the mechanical properties will be impaired. By including glycidyl group-containing styrene copolymer (C), the polyester resin composition can obtain a melt viscosity suitable for foaming. In the reaction between crystalline polyester (A1), crystalline polyester (A2) and / or amorphous polyester (B), and glycidyl group-containing styrene copolymer (C), relatively loose crosslinking and branching structures are generated that do not lead to gel formation. These reaction products contribute to increased molecular entanglement in the molten state, and exhibit an effect of increasing the melt viscosity, especially at low shear. As a result, it becomes possible to obtain a foamed molded product that has good mold filling properties, foaming state, and shape conformability of the foamed portion, as well as excellent lightness and load-bearing capacity.

[0039] As the glycidyl group-containing styrene copolymer (C), for example, one can be obtained by polymerizing a monomer mixture containing (X) a vinyl aromatic monomer, (Y) a glycidyl alkyl (meth)acrylate, and optionally (Z) a vinyl group-containing monomer other than (X) that does not contain an epoxy group (hereinafter referred to as "other vinyl group-containing monomer").

[0040] (X) Examples of vinyl aromatic monomers include styrene and α-methylstyrene. (Y) Examples of glycidyl alkyl (meth)acrylates include glycidyl (meth)acrylate, (meth)acrylate esters having a cyclohexene oxide structure, and (meth)acrylate glycidyl ethers, among which glycidyl (meth)acrylate is preferred due to its high reactivity. (Z) Other vinyl group-containing monomers include alkyl esters of (meth)acrylates having an alkyl group having 1 to 22 carbon atoms (the alkyl group may be linear or branched), such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, cyclohexyl (meth)acrylate, stearyl (meth)acrylate, and methoxyethyl (meth)acrylate; polyalkylene glycol esters of (meth)acrylates; alkoxyalkyl esters of (meth)acrylates; hydroxyalkyl esters of (meth)acrylates; dialkylaminoalkyl esters of (meth)acrylates; benzyl esters of (meth)acrylates; phenoxyalkyl esters of (meth)acrylates; isobornyl esters of (meth)acrylates; and alkoxysilylalkyl esters of (meth)acrylates. Furthermore, (meth)acrylamide, (meth)acryldialkylamide, vinyl esters such as vinyl acetate, aromatic vinyl monomers such as vinyl ethers and (meth)allyl ethers, and α-olefin monomers such as ethylene and propylene can also be used as (Z) other vinyl group-containing monomers.

[0041] The glycidyl group-containing styrene copolymer (C) is preferably a copolymer composed of (X) 20 to 99% by mass of vinyl aromatic monomers, (Y) 1 to 80% by mass of glycidyl alkyl (meth)acrylate, and (Z) 0 to 79% by mass of other vinyl group-containing monomers. More preferably, it is a copolymer composed of (X) 20 to 99% by mass, (Y) 1 to 80% by mass, and (Z) 0 to 40% by mass, and even more preferably, it is a copolymer composed of (X) 25 to 90% by mass, (Y) 10 to 75% by mass, and (Z) 0 to 35% by mass. These compositions affect the functional group concentration contributing to the reaction between the crystalline polyester (A1) and the crystalline polyester (A2) and / or the amorphous polyester (B), so it is preferable to appropriately control them within the above ranges.

[0042] Specific examples of the glycidyl group-containing styrene copolymer (C) include, for example, styrene / methyl methacrylate / acrylate copolymer, epoxy compounds of bisphenol A type, cresol novolak type, and phenol novolak type. The glycidyl group-containing styrene copolymer (C) may be only one kind or, of course, two or more kinds may be mixed and used.

[0043] The glycidyl group-containing styrene copolymer (C) preferably contains two or more glycidyl groups per molecule as a functional group capable of reacting with the carboxyl groups of the crystalline polyester (A) and the amorphous polyester (B). Thereby, partial crosslinking can be quickly introduced into the whole resin, and a part of the product by the reaction between the carboxyl groups of the crystalline polyester (A) and the amorphous polyester (B) and the glycidyl group-containing styrene copolymer (C) during melt extrusion becomes a crosslinked product, and the effect of improving the melt draw viscosity can be obtained. The glycidyl groups in the glycidyl group-containing styrene copolymer (C) may be present in, for example, any of the main chain, side chain, and terminal of the polymer.

[0044] The glycidyl group-containing styrene copolymer (C) preferably has a weight average molecular weight of 3,000 to 25,000, more preferably 4,000 to 15,000, and even more preferably 5,000 to 10,000 in order to be controlled so that the melt extensional viscosity can be adjusted. When the weight average molecular weight of the glycidyl group-containing styrene copolymer (C) is less than 3,000, unreacted glycidyl group-containing styrene copolymer (C) volatilizes in the molding process or bleeds out on the surface of the molded product, tending to cause a decrease in the adhesiveness of the product and surface contamination. Furthermore, there is also a risk that cinder is generated due to an excessive reaction between the glycidyl group-containing styrene copolymers (C), leading to a decrease in productivity during kneading and a decrease in the quality of the final product. On the other hand, when the weight average molecular weight of the glycidyl group-containing styrene copolymer (C) exceeds 25,000, the reaction during kneading extrusion becomes slow and the effect of maintaining the molecular weight decreases, or the compatibility between the glycidyl group-containing styrene copolymer (C), the crystalline polyester (A), and the amorphous polyester (B) deteriorates, so the durability of the foam molded body may decrease.

[0045] The epoxy value of the glycidyl group-containing styrene copolymer (C) is preferably 400 to 2,500 equivalents / 1 × 10 ６ g, more preferably 500 to 1,500 equivalents / 1 × 10 ６ g, and even more preferably 600 to 1,000 equivalents / 1 × 10 ６ g. When the epoxy value is less than 400 equivalents / 1 × 10 ６ g, the effect of the targeted rheology control may not be fully exhibited, and when it exceeds 2,500 equivalents / 1 × 10 ６ g, the thickening effect may become excessive and may have an adverse effect on the moldability.

[0046] The content of the glycidyl group-containing styrene copolymer (C) is 0.1 to 7 parts by mass, preferably 0.2 to 6 parts by mass, more preferably 0.3 to 5 parts by mass, and even more preferably 0.4 to 4 parts by mass, out of 100 parts by mass of the total of the crystalline polyester (A1), crystalline polyester (A2), amorphous polyester (B), and glycidyl group-containing styrene copolymer (C). If it exceeds 7 parts by mass, the thickening effect becomes excessive, which tends to adversely affect moldability and the mechanical properties of the molded product. For example, if the polyester resin composition is composed of crystalline polyester (A1), crystalline polyester (A2), and glycidyl group-containing styrene copolymer (C), and the crystalline polyester (A1) is 60 parts by mass and the glycidyl group-containing styrene copolymer (C) is 0.1 parts by mass, then the crystalline polyester (A2) is 39.9 parts by mass. In such a configuration, (A2) is determined according to the value of the glycidyl group-containing styrene copolymer (C) so that the total of (A1), (A2), and (C) is 100 parts by mass. In one embodiment, it is preferable to adjust the contents of (A1), (A2), (B), and (C) to satisfy the following formula: (A1) + (A2) + (B) = 100 - (C) where A1 ≥ 60, 0 ≤ A2 ≤ 40, 0 ≤ B ≤ 30, A2 + B ≥ 5, 0.1 ≤ C ≤ 7

[0047] Inorganic Reinforcement (D) Inorganic reinforcement (D) is an optional additive that can be added as needed. It is preferable to include inorganic reinforcement (D) because it can improve the physical properties of the foamed molded article, such as strength, rigidity, and heat resistance. Inorganic reinforcement (D) may be either a long inorganic material or an inorganic material other than a long inorganic material (hereinafter referred to as inorganic filler), and either one or both may be used in combination. Examples of long inorganic materials include fibrous materials such as glass fibers, carbon fibers, aramid fibers, alumina fibers, silicon carbide fibers, and zirconia fibers; whiskers such as aluminum borate and potassium titanate; needle-shaped wollastonite; milled fibers; and other long inorganic materials. The shape of the inorganic filler is not particularly limited and may be other shapes such as short granules, powder, flakes, or spheres. Examples of inorganic materials for inorganic fillers include glass beads, glass flakes, glass balloons, silica, talc, kaolin, wollastonite, mica, alumina, hydrotalcite, montmorillonite, graphite, carbon nanotubes, fullerenes, zinc oxide, indium oxide, tin oxide, iron oxide, titanium oxide, magnesium oxide, aluminum hydroxide, magnesium hydroxide, red phosphorus, calcium carbonate, potassium titanate, lead zirconate titanate, barium titanate, aluminum nitride, boron nitride, zinc borate, aluminum borate, barium sulfate, magnesium sulfate, and layered silicates that have been organically treated for delamination purposes. Long-length inorganic reinforcing materials and inorganic fillers can be applied according to the required properties. The inorganic reinforcing material (D) may be one type only or two or more types in combination.

[0048] The length of the fibrous material is not particularly limited, but for example, glass fibers and carbon fibers are preferably in the form of chopped strands cut to a fiber length of about 5 to 30 mm. The cross-sectional shape of the fibrous material is not particularly limited. For example, the cross-sectional shape of glass fibers may be circular or non-circular. Glass fibers with a non-circular cross-section may be approximately elliptical, approximately oblong, or approximately cocoon-shaped in a cross-section perpendicular to the length direction of the fiber, and preferably have a flattening degree of 1.5 to 8. The flattening degree is the ratio of the major axis to the minor axis, assuming a rectangle with the smallest area circumscribing the cross-section perpendicular to the longitudinal direction of the glass fiber, where the length of the long side of this rectangle is the major axis and the length of the short side is the minor axis. The thickness of the fibrous material is not particularly limited. For example, the thickness of glass fibers is approximately 1 to 20 μm for the minor axis and 2 to 100 μm for the major axis.

[0049] The inorganic reinforcing material (D) is preferably pre-treated with a coupling agent such as an organosilane compound, organotitanium compound, organoborane compound, or epoxy compound to improve its affinity with the crystalline polyester (A) and / or amorphous polyester (B), and is particularly preferably one that readily reacts with carboxylic acid groups and / or hydroxyl groups. Any of the coupling agents such as silane coupling agents, titanate coupling agents, or aluminum coupling agents may be used, but silane coupling agents such as epoxysilane coupling agents are particularly preferred. For example, a polyester resin composition containing glass fibers treated with a coupling agent is preferred because it yields a foamed molded product with excellent mechanical properties and appearance. It is preferable to pre-treat with a coupling agent, but the coupling agent may also be added later.

[0050] The amount of inorganic reinforcing material (D) is 0 to 100 parts by mass per 100 parts by mass of the total of crystalline polyester (A1), crystalline polyester (A2), amorphous polyester (B), and glycidyl group-containing styrene copolymer (C). Here, 0 parts by mass means that the inorganic reinforcing material (D) is not included, and if the inorganic reinforcing material (D) is included, it is greater than 0 parts by mass (i.e., not including 0 parts by mass). The amount of inorganic reinforcing material (D) is preferably 0 to 60 parts by mass, more preferably greater than 0 parts by mass to 55 parts by mass, and even more preferably 5 to 50 parts by mass. If the amount of inorganic reinforcing material (D) is too high, the elongation of the molten polyester resin decreases, making it difficult to form a foamed layer. In one embodiment, the amount of inorganic reinforcing material (D) is preferably 60 parts by mass or less.

[0051] Other Additives: The polyester resin composition of this disclosure may contain various known additives (hereinafter referred to as "other additives"), provided that they do not impair the effects of this disclosure. Examples of other additives include stabilizers, flame retardants, release agents, impact modifiers, colorants, and metal corrosion inhibitors. There may be only one or more other additives.

[0052] Examples of stabilizers include organic antioxidants such as hindered phenol antioxidants, sulfur antioxidants, phosphorus antioxidants, phosphite compounds, and thioether compounds; heat stabilizers; light stabilizers such as hindered amine, benzophenone, and imidazole compounds; ultraviolet absorbers; and metal deactivators.

[0053] While there are no particular restrictions on the flame retardant, it is preferable to use non-halogenated flame retardants such as phosphate esters, melamine polyphosphate, metal salts of phosphinic acid, and melamine cyanurate.

[0054] Examples of release agents include long-chain fatty acids or their esters or metal salts, amide compounds, polyethylene wax, silicone, and polyethylene oxide. The release agent may be used alone or in combination of two or more types.

[0055] Examples of sliding properties improving materials include high molecular weight polyethylene, acid-modified high molecular weight polyethylene, fluororesin powder, molybdenum disulfide, silicone resin, silicone oil, zinc, graphite, and mineral oil.

[0056] Examples of colorants include those for black, gray, brown, blue, and green. Using a colored thermoplastic polyester resin composition will yield a colored foam. Examples of colorants include organic and inorganic pigments and dyes. Conventionally known pigments and dyes can be used.

[0057] Metal corrosion inhibitors are additives that are effective in preventing metal corrosion, such as in molds, and examples include hydrotalcite compounds.

[0058] Furthermore, the polyester resin composition may also contain thermoplastic resins other than polyester, to the extent that they do not impair the effects of the present disclosure. Examples include polyphenylene sulfide (PPS), liquid crystal polymer (LCP), aramid resin, polyether ether ketone (PEEK), polyether ketone (PEK), polyetherimide (PEI), thermoplastic polyimide, polyamideimide (PAI), polyether ketone ketone (PEKK), polyphenylene ether (PPE), polyethersulfone (PES), polysulfone (PSU), polyarylate (PAR), polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polycarbonate (PC), polyoxymethylene (POM), polypropylene (PP), polyethylene (PE), polymethylpentene (TPX), polystyrene (PS), polymethyl methacrylate, acrylonitrile-styrene copolymer (AS), acrylonitrile-butadiene-styrene copolymer (ABS), and polyamide (PA). The blending method for these thermoplastic resins is not particularly limited; for example, they may be blended in a molten state by melt kneading with crystalline polyester (A) or amorphous polyester (B). Compatibilizers such as reactive compounds or block polymers may be added as needed, and the polymers may be acid-modified. The amount of thermoplastic resin added should be selected to be optimal; for example, it may be 0 to 50 parts by mass per 100 parts by mass of the total of crystalline polyester (A) and amorphous polyester (B).

[0059] The foamed molded article of this disclosure is obtained by foam molding the above-mentioned polyester resin composition. The foamed molded article of this disclosure has a sandwich structure in which non-foamed skin layers are provided on both sides of the foamed layer, in other words, a structure in which the foamed layer is sandwiched between non-foamed skin layers on both sides. The size of the foamed molded article is not particularly limited, but for example, the thickness is about 1 to 30 mm.

[0060] A foamed molded article with a sandwich structure obtained using the polyester resin composition of this disclosure has a foamed layer with a uniform cellular foamed structure and a non-foamed skin layer with excellent appearance, as well as excellent lightness and load-bearing capacity.

[0061] The foam layer is preferably composed of a continuous resin phase and independent foam cells. The continuous resin phase refers to a portion of the cured polyester resin composition that does not have voids, that is, a region in the cured polyester resin composition where the resin does not have voids and is formed by continuous resin. The average cell diameter of the independent foam cells is preferably 10 to 800 μm, more preferably 10 to 700 μm. The foamed molded body exhibits different properties depending on the cell diameter of the independent foam cells. Even if the weight of the foamed molded body is the same, a smaller cell diameter results in higher rigidity. Also, a larger cell diameter results in better cushioning and energy absorption properties in fracture. It is desirable that the cell diameter of each independent foam cell has little variation, and is preferably uniform and without variation. It is preferable that the average cell diameter is within the above range, as this allows appropriate pressure to be applied to the non-foamed skin layer from inside the foamed molded body, and that it can be molded with external pressure that does not inhibit cell growth, thereby forming a foamed molded body with the desired effect. If the average cell diameter is less than 10 μm, the internal pressure of the foamed molded body is low, resulting in insufficient pressure during the formation of the non-foamed skin layer, which can lead to poor appearance such as sink marks. Alternatively, if the cells cannot grow due to external pressure, cell growth may be suppressed too much, preventing the desired low-density structure from being obtained. If the average cell diameter exceeds 800 μm, the load-bearing capacity is low, and even adding inorganic reinforcing material (D) may not sufficiently enhance the reinforcing effect.

[0062] The thickness of the non-foamed skin layer is preferably 50 to 800 μm, more preferably 80 to 700 μm, and even more preferably 100 to 500 μm. If the thickness of the non-foamed skin layer is too thin, a good appearance may not be obtained. If the thickness of the non-foamed skin layer is too thick, the specific gravity of the foamed layer becomes too low, and the foamed structure may not be obtained in a uniform cellular state. In a preferred embodiment of this disclosure, it is preferable that the average cell diameter of the foamed layer is less than the thickness of the non-foamed skin layer. If the average cell diameter of the foamed layer is greater than or equal to the thickness of the non-foamed skin layer, the load-bearing capacity of the foamed molded article may be significantly reduced.

[0063] Method for Manufacturing Polyester Resin Compositions The polyester resin composition in this disclosure is a mixture of a crystalline polyester resin (A1), a crystalline polyester (A2), an amorphous polyester (B), a glycidyl group-containing styrene copolymer (C), and an inorganic reinforcing material (D) or additives as needed, and the mixing method is not particularly limited. For example, the glycidyl group-containing styrene copolymer (C) can be added to the crystalline polyester resin (A1), crystalline polyester (A2), and / or amorphous polyester (B) (hereinafter referred to as polyester components). Specifically, the glycidyl group-containing styrene copolymer (C) can be added in one of the following ways: 1) added to the polymerizer of the polyester components after polymerization is complete; 2) directly added to the molten polyester components immediately after they leave the polymerizer and kneaded; or 3) added to the solidified (e.g., powder, pelletized, etc.) polyester components and then melt-kneaded. In method 1) or 2) above, the polyester component is in a molten state, so it can be directly increased in melt viscosity by adding a glycidyl group-containing styrene copolymer (C), etc. However, in method 3) above, it is desirable to heat and remelt the polyester component in order to increase its melt viscosity by uniformly dispersing and mixing the glycidyl group-containing styrene copolymer (C), etc.

[0064] There are no particular restrictions on the method of heating and remelting; any method well known to those skilled in the art may be used. For example, a single-screw extruder, a twin-screw extruder, a pressure kneader, a Banbury mixer, etc., can be used. Among these, a twin-screw extruder is particularly preferred. The operating conditions of the twin-screw extruder can be adjusted as appropriate; for example, the operating temperature should be set to around the melting point of polyester + 25°C. The operating time should be adjusted to achieve the desired melt viscosity, for example, within 10 minutes, preferably from 1 minute to several minutes. The screw configuration of the extruder preferably incorporates several kneading discs that provide excellent kneading.

[0065] The foamed molded article of the present disclosure having the sandwich structure described above is preferably obtained by foaming the polyester resin composition using a specific foaming method (hereinafter referred to as the mold expansion method) that expands the mold during injection molding. The mold expansion method is a method of obtaining a foamed molded article by injecting and filling a cavity 3 formed by a plurality of clamped molds 1 and 2 from an injection molding machine 4 together with a chemical foaming agent and / or a supercritical inert gas (hereinafter these may be collectively referred to as the "foaming agent"), and then moving at least one mold (hereinafter sometimes referred to as the "operating mold") 2 in the mold opening direction to expand the volume of the cavity 3 when a non-foamed skin layer with a thickness of 100 μm to 800 μm is formed on the surface, thereby expanding the volume of the cavity 3. Specifically, after filling the cavity 3 with the polyester resin composition M and the foaming agent, a non-foamed skin layer is formed on the surface of the polyester resin composition M filled in the cavity 3. When this non-foamed skin layer reaches a predetermined thickness (100 μm to 800 μm), the operating mold 2 is moved in the mold opening direction (core back) to expand the volume of the cavity 3. To move the operating mold 2 when the non-foamed skin layer reaches a predetermined thickness, for example, after filling with the polyester resin composition M, the operating mold 2 can be moved (core back) within an optimal delay time. This makes it possible to form a foamed structure with a more uniform cellular state.

[0066] The movement speed (core back speed) of the operating mold 2 is preferably in the range of 0.1 to 5 mm / second. If the core back speed is within this range, a more uniform cellular foam structure can be formed. Note that the core back speed does not necessarily have to be constant as long as it is within the above range, and may be changed as appropriate.

[0067] The above-mentioned foaming agent is added to the resin molten in the resin melting zone of the molding machine as a gas component that acts as a foaming nucleus or as a source of foam. Examples of chemical foaming agents include inorganic compounds such as ammonium carbonate and sodium bicarbonate, as well as organic compounds such as azo compounds, sulfohydrazide compounds, nitroso compounds, and azide compounds. Examples of azo compounds include diazocarbonamide (ADCA), 2,2-azoisobutyronitrile, azohexahydrobenzonitrile, and diazoaminobenzene, with ADCA being preferred among these. Examples of sulfohydrazide compounds include benzenesulfohydrazide, benzene 1,3-disulfohydrazide, diphenylsulfone-3,3-disulfonehydrazide, and diphenyloxide-4,4-disulfonehydrazide. Examples of nitroso compounds include N,N-dinitrosopentaethylenetetramine (DNPT) and N,N-dimethylterephthalate. Examples of azide compounds include terephthal azide and p-ter-butylbenz azide.

[0068] When using a chemical blowing agent, a blowing agent masterbatch can be used with a thermoplastic resin base material that has a melting point lower than the decomposition temperature of the chemical blowing agent, in order to uniformly disperse the chemical blowing agent in the polyester resin composition. The thermoplastic resin used as the base material (hereinafter referred to as the base thermoplastic resin) is not particularly limited as long as it has a melting point lower than the decomposition temperature of the chemical blowing agent, and examples include polystyrene (PS), polyethylene (PE), and polypropylene (PP). The mixing ratio of the chemical blowing agent to the base thermoplastic resin in the blowing agent masterbatch is preferably 10 to 100 parts by mass of the chemical blowing agent per 100 parts by mass of the base thermoplastic resin. If the amount of chemical blowing agent is less than 10 parts by mass, the amount of masterbatch (base thermoplastic resin) mixed into the thermoplastic polyester resin composition will be too large, which may reduce the physical properties of the foamed molded product. If the amount of chemical blowing agent exceeds 100 parts by mass, problems may arise with the dispersibility of the chemical blowing agent, making masterbatch formation difficult.

[0069] From the viewpoint of improving the recyclability of foamed molded products, physical foaming without the use of chemical foaming agents is preferred. When using a supercritical inert gas as a foaming agent, carbon dioxide and / or nitrogen are used as the inert gas. Specifically, supercritical carbon dioxide and / or supercritical nitrogen (hereinafter sometimes referred to as supercritical carbon dioxide / nitrogen) are used. Supercritical carbon dioxide / nitrogen may be used alone or mixed together. Supercritical carbon dioxide is preferable because it allows for a higher foaming ratio by increasing the injection amount. Supercritical nitrogen is also preferable because it allows for the formation of finer cells. Considering the above characteristics of supercritical carbon dioxide / nitrogen, supercritical carbon dioxide and supercritical nitrogen may be used in combination depending on the state of the foamed molded product. When using supercritical carbon dioxide / nitrogen in combination, the mixing ratio is preferably in the range of 1:9 to 9:1 in molar ratio.

[0070] A supercritical state is a state in which, as the temperature and pressure of a substance are increased, the distinction between the gas phase and the liquid phase disappears beyond a certain point (critical point). The temperature and pressure at which this supercritical state is reached are called the critical temperature and critical pressure. Supercritical carbon dioxide / nitrogen are critical fluids, and because they have a higher density than the gas and lower viscosity than the liquid, they easily diffuse into a molten polyester resin composition. The critical temperature of carbon dioxide is 31.2°C and the critical pressure is 7.38 MPa, while the critical temperature of nitrogen is -147.1°C and the critical pressure is 3.4 MPa. Above these critical temperatures and pressures, the substance enters a supercritical state and exhibits the above-mentioned characteristics as a critical fluid.

[0071] The supercritical carbon dioxide / nitrogen used as a blowing agent is preferably 0.02 to 30 parts by mass, more preferably 0.03 to 20 parts by mass, per 100 parts by mass of the resin component of the polyester resin composition. If the amount of supercritical carbon dioxide / nitrogen is less than 0.02 parts by mass, uniform and fine foam cells may not be obtained, and if it exceeds 30 parts by mass, the appearance of the surface of the foamed molded article may be impaired.

[0072] For example, to inject a molten polyester resin composition M into a cavity 3 together with a blowing agent, as shown in Figure 1, the molten thermoplastic polyester resin composition M and the blowing agent should be mixed in the plasticizing region 4a inside the injection molding machine 4. When using supercritical carbon dioxide / nitrogen as the blowing agent, methods such as injecting gaseous carbon dioxide and / or nitrogen directly or pressurized with a booster pump 6 into the injection molding machine 4 from a gas cylinder 5, as shown in Figure 1, or injecting liquid carbon dioxide and / or nitrogen into the injection molding machine 4 with a plunger pump can be employed. From the viewpoint of solubility, penetration, and diffusion into the molten polyester resin composition, the injected carbon dioxide and / or nitrogen must be in a supercritical state inside the injection molding machine 4.

[0073] The polyester resin compositions of this disclosure are suitable for automotive resin molded products (in-vehicle parts). The polyester resin compositions of this disclosure can be foam-molded into in-vehicle parts of various shapes. Examples of in-vehicle parts include automotive exterior parts such as fenders, grilles, bumpers, door panels, floor rails, and light housings; and automotive interior parts such as instrumentation components, interior surfaces, dashboard front plates, door handles, glove compartments, console panels, console trays, trays installed on the backs of seats, and vents.

[0074] This application claims the benefit of priority under Japanese Application No. 2024-191497, filed on 31 October 2024. The entire specification of Japanese Application No. 2024-191497 is incorporated herein by reference.

[0075] The present invention will be described in more detail below with reference to examples, but the present invention is not limited by the following examples, and it is certainly possible to implement it with appropriate modifications within the scope that is consistent with the spirit of the preceding and following descriptions, and all such modifications are included within the technical scope of the present invention. In the following, unless otherwise specified, "parts" means "parts by mass" and "%" means "percent mass".

[0076] Crystalline polyester (A1) The following PBT (terephthalic acid / 1,4-butanediol), PBT-DOH (terephthalic acid / 1,4-butanediol / dimerdiol), and PCT-DOH (terephthalic acid / 1,4-cyclohexanedimethanol / dimerdiol) were used as crystalline polyester (A1).

[0077] PBT: Manufactured by Toyobo MC Corporation. Reduced viscosity: 0.95 dl / g

[0078] PBT-DOH: In a reaction vessel equipped with a stirrer, condenser, and thermometer, 694.5 parts of dimethyl terephthalate, 763.1 parts of 1,4-butanediol, 259.2 parts of Pripol 2033 (dimer diol manufactured by Cargill), 0.8 parts of tetra-n-butyl titanate as a catalyst, and 2.0 parts of AO-330 (manufactured by ADEKA) as an additive were charged, and the transesterification reaction was carried out while raising the temperature from 150°C to 230°C over 3 hours. Then, the pressure in the system was gradually reduced to 5 mmHg over 20 minutes, and the polycondensation reaction was carried out at 250°C for 60 minutes under a vacuum of 0.3 mmHg or less. The obtained polyester resin was dissolved in a mixed solvent of deuterated chloroform / trifluoroacetic acid (weight ratio 85 / 15), and ¹H-NMR measurements were performed using a nuclear magnetic resonance (NMR) spectrometer (Bruker AVANCE NEO 500). The resin composition was calculated in molar ratio from the integral ratio. Composition analysis by ¹H-NMR revealed that the polyhydric alcohol component was 1,4-butanediol / dimergol = 87 / 13 in molar ratio. The reduced viscosity was 1.07 (dl / g), and the melting point determined by DSC was 200°C.

[0079] PCT-DOH: In a reaction vessel equipped with a stirrer, condenser, and thermometer, 473.5 parts of dimethyl terephthalate, 744.0 parts of 1,4-cyclohexanedimethanol, 296.2 parts of Pripol 2033 (dimergol manufactured by Cargill), 0.8 parts of tetra-n-butyl titanate as a catalyst, and 2.0 parts of AO-330 (manufactured by ADEKA) as an additive were charged, and the esterification reaction was carried out while raising the temperature from 180°C to 260°C over 4 hours. Then, the pressure in the system was gradually reduced to 5 mmHg over 20 minutes, and the polycondensation reaction was carried out at 285°C for 220 minutes under a vacuum of 0.3 mmHg or less. The obtained polyester resin was dissolved in a mixed solvent of deuterated chloroform / trifluoroacetic acid (weight ratio 85 / 15), and ¹H-NMR measurements were performed using a nuclear magnetic resonance (NMR) spectrometer (Bruker AVANCE NEO 500). The resin composition was calculated in molar ratio from the integral ratio. Composition analysis by ¹H-NMR revealed that the polyhydric alcohol component was 1,4-cyclohexanedimethanol / dimergol in molar ratio of 82 / 18. The reduced viscosity was 0.65 (dl / g), and the melting point determined by DSC was 257°C.

[0080] Crystalline Polyester (A2) The following crystalline polyesters (A2) were used: PET (polyethylene terephthalate) and I-PBT (terephthalic acid / isophthalic acid / 1,4-butanediol). PET: Manufactured by Toyobo Co., Ltd. Reduced viscosity 0.63 dl / g I-PBT: Manufactured by Toyobo MC Co., Ltd. Copolymer with a composition ratio of TPA / IPA / 1,4-BD = 70 / 30 / 100 (mol%), reduced viscosity 0.73 dl / g

[0081] Amorphous polyester (B) As amorphous polyester (B), NPG-PET (terephthalate / ethylene glycol / neopentyl glycol) NPG-PET: Manufactured by Toyobo MC Corporation Copolymer with a composition ratio of TPA / EG / NPG = 100 / 70 / 30 (mol%), reduced viscosity 0.83 dl / g

[0082] Glycidyl group-containing styrene copolymer (C) St-GMA: Alphon "UG4050" manufactured by Toagosei Co., Ltd., styrene / glycidyl acrylate copolymer

[0083] Inorganic Reinforcement Material (D) Inorganic Filler: "Talcan Powder PK-P" manufactured by Hayashi Chemical Co., Ltd. Glass Fiber: "T-120H" manufactured by Nippon Electric Glass Co., Ltd.

[0084] Other additives: Stabilizer: ADEKA Corporation "ADEKA Stab AO-20" Release agent: Clariant Japan Co., Ltd. "Montanate ester wax WE40" Black pigment: Resino Color Industries Co., Ltd. "ABF-T9534"

[0085] Each resin composition was prepared using the raw materials and proportions (parts by mass) shown in Table 1. Specifically, the mixture obtained by pre-mixing polyester resins (A1), (A2), (B), glycidyl group-containing styrene copolymer (C), and other additives (0.4 parts by mass of stabilizer, 0.5 parts by mass of mold release agent, and 1.0 part by mass of black pigment) was simultaneously fed from the hopper into the screw and melt-kneaded in an extruder (35φ twin-screw extruder: manufactured by Coperion Co., Ltd.). Then, an inorganic reinforcing material (D) was fed into the extruder via side feed. At this time, the cylinder temperature was set to 100°C in the zone closest to the hopper, and 20 to 30°C higher than the melting point of the respective crystalline polyesters in the other zones. Melt-kneading was performed at a discharge rate of 25 kg / hr and a screw rotation speed of 150 rpm. After cooling the strands discharged from the extruder in a water bath, they were pelletized with a strand cutter and dried at 130°C for 5 hours to obtain pelletized polyester resin compositions.

[0086] Next, a foamed molded body was produced using the above-mentioned pelletized polyester resin composition by a mold expansion method. The mold used was a flat plate mold consisting of a fixed mold and a movable mold that, when clamped, could form a cavity with a width of 100 mm, a length of 100 mm, and a thickness of 1.5 mm. The gate was a trapezoidal shape with a lower base width of 5.5 mm, an upper base width of 4.0 mm, and a thickness of 1.4 mm in the central part of the 100 mm wide cavity, and was designed to flow in the length direction. Specifically, the cylinder temperature of an electric injection molding machine with a mold clamping force of 1800 kN, a bore diameter of 42 mm, and a screw with an L / D ratio of 30 was set to 20 to 50°C higher than the melting point of the polyester resin composition. Carbon dioxide was injected in a supercritical state in the plasticizing region at a ratio of 0.3 parts by mass per 100 parts by mass of the resin component in the polyester resin composition. After injection filling into a mold whose surface temperature was controlled to 40 to 90°C, the operating mold was moved 1.5 mm in the mold opening direction to expand the cavity volume and obtain a foamed molded body. At this time, the delay time from the completion of injection to the start of core back was set to 0.1 to 1.0 seconds, and the movement speed of the operating mold (core back speed) was set to 0.1 to 1.0 mm / second. The optimal conditions for mold surface temperature, delay time, and movement speed were selected for each example.

[0087] Evaluation Criteria: Melting point Tm (°C), Cooling crystallization temperature Tc2 (°C) A sample (resin composition) dried at 130°C for 5 hours was weighed out at 10 mg in an aluminum pan (TA Instruments, "Catalog No. 900793.901"), sealed with an aluminum lid (TA Instruments, "Catalog No. 900794.901"), and heated from room temperature at 20°C / min using a differential scanning calorimeter (TA Instruments, "DSCQ100"). The endothermic peak temperature due to melting was taken as the melting point (Tm). After holding at 300°C for 3 minutes, it was cooled to 23°C at 10°C / min. The exothermic peak temperature at this time was taken as the cooling crystallization temperature Tc2 (°C).

[0088] The maximum pressure was measured and evaluated when injecting (filling) the fillable molten resin into the cavity. ○ (Good): Maximum filling pressure is less than 180 MPa. × (Poor): Maximum filling pressure is 180 MPa or higher.

[0089] For the molded body obtained in a foamed state, a section was cut approximately 15 mm toward the gate from the end opposite the gate, and a 5 mm wide cross-section near the center in the width direction was observed and evaluated using a stereomicroscope. ○ (Good): Two or fewer coarse voids exceeding 800 μm × (Poor): More than two voids exceeding 800 μm, or the presence of voids exceeding 1500 μm

[0090] Appearance: The surface condition of the foamed molded product was visually observed to confirm its condition. For compositions without glass fibers, the presence or absence of silver, flash, swirling marks, etc., due to the effects of the foaming agent gas was evaluated. For compositions containing inorganic reinforcing material (D) (glass fiber, inorganic filler), in addition to the above, the presence or absence of surface lifting of glass fibers was checked and evaluated. ○ (Good): No silver, flash, swirling marks, or lifting of inorganic reinforcing material were observed. × (Poor): Silver, flash, swirling marks, and lifting of inorganic reinforcing material were observed.

[0091] The surface condition of the obtained foamed molded body was visually observed to check for the presence or absence of surface blistering caused by the non-foaming phase in the inner layer due to gas. ○ (Good): No blistering on the surface. × (Poor): Blistering is present on the surface.

[0092]

[0093] Comparative Examples 1 and 2: Polybutylene terephthalate did not satisfy formula (1) (Tm - Tc2 = 26°C), and the total amount of crystalline polyester (A2) and / or amorphous polyester (B) did not meet the requirement (5 parts by mass or more). Core-back injection foam molding solidifies quickly, so even without reinforcing materials, defects such as flash and silver streaks occur in the appearance due to the effect of the foaming agent gas, and if the foaming timing is after the solidification of the molten polybutylene terephthalate, cracks occur in the foam layer. Even when amorphous polyester (B) is added, as in Comparative Example 2, if the amount is too low, formula (1) (Tm - Tc2 ≥ 30°C) cannot be satisfied, and no significant improvement was observed. The comparative example with poor foaming state had large voids as shown in Figure 2(b). The inventive example with good foaming state had a good foaming state as shown in Figure 2(a).

[0094] Comparative Example 3 Comparative Example 3 is polybutylene terephthalate with a large amount of amorphous polyester (B) added, and satisfies formula (1) (Tm - Tc2 = 57°C). However, the amount of crystalline polyester (A1) is less than 60 parts by mass, and the amount of amorphous polyester (B) is more than 30 parts by mass. As a result, solidification takes too long, causing the cells to burst and become coarse during foaming, and the non-foamed layer on the surface is also soft, causing the surface of the molded product to bulge and severely impairing its appearance.

[0095] Comparative Examples 4 and 5: Comparative Example 4 did not contain the glycidyl group-containing styrene copolymer (C), so the solidification temperature was appropriate, but a good foamed layer could not be obtained due to insufficient melt viscosity during foaming. In Comparative Example 5, the amount of glycidyl group-containing styrene copolymer (C) was too high, resulting in excessively high melt viscosity during injection, which hindered filling into a thin cavity of 1.5 mm thickness, and the melt viscosity became too high. As a result, the dispersion of the foaming agent gas was poor, and flashing and silver streaks occurred.

[0096] Comparative Examples 6 and 7: Furthermore, when an inorganic reinforcing material was added to polyester with a low formula (1) (Tm-Tc2), the glass fibers solidified in a floating state, resulting in poor foaming, or the foamed molded product had glass fibers floating on the surface, resulting in poor appearance.

[0097] 1. Fixed mold 2. Moving mold 3. Cavity 4. Injection molding machine 5. Gas cylinder 6. Booster pump 7. Pressure control valve M. Polyester resin composition

Claims

1. A thermoplastic polyester resin composition comprising a crystalline polyester (A1), a crystalline polyester other than the crystalline polyester (A2), and / or an amorphous polyester (B), a glycidyl group-containing styrene copolymer (C), and further optionally an inorganic reinforcing material (D), wherein, in a total of 100 parts by mass of the crystalline polyester (A1), the crystalline polyester (A2), the amorphous polyester (B), and the glycidyl group-containing styrene copolymer (C), the composition is: 60 parts by mass or more of the crystalline polyester (A1), 0 to 40 parts by mass of the crystalline polyester (A2), 0 to 30 parts by mass of the amorphous polyester (B), and the total amount of the crystalline polyester (A2) and the amorphous polyester (B) is 5 parts by mass or more, and the glycidyl group-containing styrene copolymer (C) is 0.1 to 7 parts by mass, A thermoplastic polyester resin composition for foam molding, comprising 0 to 100 parts by mass of the inorganic reinforcing material (D) per 100 parts by mass of the total of the crystalline polyester (A1), the crystalline polyester (A2), the amorphous polyester (B), and the glycidyl group-containing styrene copolymer (C), and satisfying the following formula (1): Tm - Tc2 ≥ 30°C (1) where, Tm (°C): Melting point of the thermoplastic polyester resin composition determined by differential scanning calorimeter (DSC) Tc2 (°C): Cooling crystallization temperature of the thermoplastic polyester resin composition determined by differential scanning calorimeter (DSC) 2. The thermoplastic polyester resin composition for foam molding according to claim 1, wherein the crystalline polyester (A1) mainly comprises terephthalic acid or a derivative thereof as a polycarboxylic acid component, and mainly comprises a linear aliphatic polyhydric alcohol having 4 or fewer carbon atoms, or a polyhydric alcohol having 6 or more carbon atoms with an alicyclic skeleton as a polyhydric alcohol component.

3. The thermoplastic polyester resin composition for foam molding according to claim 1, wherein the crystalline polyester (A2) is polyethylene terephthalate or polybutylene terephthalate, which may be copolymerized.

4. The thermoplastic polyester resin composition for foam molding according to claim 1, wherein the amorphous polyester (B) is copolymerized polyethylene terephthalate.

5. The thermoplastic polyester resin composition for foam molding according to claim 2, wherein the crystalline polyester (A1) is a copolymerized polyester obtained by copolymerizing dimerol as a diol component.

6. The thermoplastic polyester resin composition for foam molding according to claim 2, wherein the crystalline polyester (A1) is polybutylene terephthalate.

7. The thermoplastic polyester resin composition for foam molding according to claim 2, wherein the crystalline polyester (A1) is a copolymer of polybutylene terephthalate or polycyclohexylene dimethylene terephthalate and dimergol.

8. The thermoplastic polyester resin composition for foam molding according to claim 3, wherein the crystalline polyester (A2) is a copolymerized polyester obtained by copolymerizing an aromatic dicarboxylic acid other than terephthalic acid as the dicarboxylic acid component.

9. The thermoplastic polyester resin composition for foam molding according to claim 3, wherein the crystalline polyester (A2) is a copolymer of polybutylene terephthalate and isophthalic acid.

10. The thermoplastic polyester resin composition for foam molding according to claim 4, wherein the amorphous polyester (B) is copolymerized polyethylene terephthalate obtained by copolymerizing an aliphatic diol having a branched chain structure as a diol component.

11. The thermoplastic polyester resin composition for foam molding according to claim 4, wherein the amorphous polyester (B) is a copolymer of polyethylene terephthalate and neopentyl glycol.

12. The thermoplastic polyester resin composition for foam molding according to claim 1, wherein the glycidyl group-containing styrene copolymer (C) is a copolymer comprising a vinyl aromatic monomer and a glycidyl alkyl (meth)acrylate as constituent units.

13. The thermoplastic polyester resin composition for foam molding according to claim 12, wherein the vinyl aromatic monomer is styrene and the glycidyl alkyl (meth)acrylate is glycidyl acrylate.

14. A foamed molded article obtained by molding a thermoplastic polyester resin composition for foam molding according to any one of claims 1 to 13, wherein the foamed molded article has non-foamed skin layers on both sides of the foamed layer.

15. An in-vehicle component obtained by molding a thermoplastic polyester resin composition for foam molding according to any one of claims 1 to 13.

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