Polyester elastomer resin composition for foam molding and foam molded body

Abstract

Provided is a polyester elastomer resin composition for foam molding, the polyester elastomer resin composition being capable of producing a foam molded body having improved foam cell uniformity, preferably improved foam cell uniformity and temporal stability of foam cell uniformity, even in a polyester elastomer having a high proportion of hard segment. A polyester elastomer resin composition for foam molding according to the present invention contains, as a main component, a thermoplastic polyester elastomer (A) which is composed of: a hard segment made of a polyester having an aromatic dicarboxylic acid and an aliphatic and / or alicyclic diol as constituent components; and at least one soft segment selected from an aliphatic polyether, an aliphatic polyester, and an aliphatic polycarbonate, wherein the content of the hard segment is 50-95 mass%. The difference between the melting point and the temperature-lowering crystallization temperature of the polyester elastomer resin composition and the melt viscosity of the polyester elastomer resin composition satisfy a specific relationship.

Description

Polyester elastomer resin composition for foam molding and foam molded article

[0001] The present invention relates to a polyester elastomer resin composition for foam molding that can be used to stably produce foams that are lightweight, have high impact absorption properties, and are excellent in heat resistance and mechanical properties.

[0002] In recent years, from the viewpoint of energy conservation, there has been a strong trend to use foam molded products instead of metal materials, which are inferior in terms of light weight, in the fields of automobiles, aircraft, railway vehicles, etc. In particular, elastomer foams are not only useful for weight reduction but also have excellent shock absorption properties, and are therefore widely used in components such as cushioning materials for electronic devices and furniture, automotive interior materials, and food packaging materials.

[0003] Conventionally, as elastomer foams, uncrosslinked or crosslinked polyolefin elastomer foams have been known (see Patent Document 1). However, polyolefin elastomer foams have a problem in that they have a large permanent set, which deteriorates the processability and product properties when punching thin-walled members such as electronic components.

[0004] Furthermore, polyurethane elastomers are preferably used for impact absorbing members, and Patent Document 2 proposes a method for producing impact absorbing members using polyurethane elastomer foam. However, urethane foam has problems with heat resistance and hot water resistance, and furthermore, it generates cyanide gas and the like when burned, which poses a problem of environmental pollution.

[0005] Foams using polyester elastomers are also known, and because of their excellent heat aging resistance, weather resistance, and abrasion resistance, they are being used in automobile parts, particularly parts used in high-temperature environments and automobile interiors. Patent Document 3 proposes a manufacturing method for such foams, and although high-quality foamed molded products have been produced, the expansion ratio is low and it has not yet been possible to produce foams with a low density that is sufficient for weight reduction.

[0006] JP 2004-250529 A JP 2007-99269 A JP 2012-140532 A

[0007] Furthermore, polyester elastomers with more hard segments than soft segments have a higher deflection temperature under load and retain excellent mechanical properties even in high-temperature environments compared to polyester elastomers with more soft segments. However, they are difficult to raise to a melt viscosity suitable for foaming, and the expansion ratio tends to vary over time or depending on the location where the foam is measured, making it difficult to consistently produce foamed molded articles of the same quality.

[0008] The present invention has been made in consideration of the current state of the art, and its object is to provide a polyester elastomer resin composition for foam molding that can produce foams with small intracellular variation in foam cell diameter (i.e., improved foam cell uniformity) even when a polyester elastomer with a high hard segment ratio is used, preferably a polyester elastomer resin composition for foam molding that can stably produce foams with improved foam cell uniformity over an extended period of time (i.e., improved stability of foam cell uniformity over time). Another preferred object of the present invention is to provide a polyester elastomer resin composition for foam molding that has stable foaming properties and can stably produce foams that are lightweight, have high impact absorption, and are excellent in heat resistance and mechanical properties, even when a polyester elastomer with a high hard segment ratio is used.

[0009] The present inventors conducted extensive research to determine the cause of unstable foaming (i.e., failure to obtain uniform foam cell diameters). As a result, they discovered that the factor that destabilizes foaming is related to the temperature dependence of melt viscosity. In polyester elastomers with a higher proportion of amorphous soft segments than crystalline hard segments, the cooling crystallization temperature (TC2) becomes broad, no clear crystallization peak is observed, and solidification proceeds slowly. In contrast, polyester elastomers with a higher proportion of hard segments exhibit a clear crystallization peak, and once solidification begins during the cooling process, solidification proceeds rapidly. They also have a high TC2. Therefore, polyester elastomers with a higher proportion of hard segments are significantly affected by the temperature of the polyester elastomer resin composition during foaming. Therefore, during foaming, the resin temperature of the polyester elastomer resin composition must be sufficiently higher than TC2, but the higher the resin temperature, the more easily the foaming property changes. It was believed that the behavior of these molten polyester elastomer resin compositions during the cooling process destabilizes foaming property.

[0010] As a result of intensive investigations aimed at solving the above-mentioned problems, the present inventors have found that, in a polyester elastomer having a high hard segment ratio, all of the above-mentioned problems can be solved by controlling the temperature dependence of the melt viscosity through resin (composition) design, and have thus completed the present invention.

[0011] That is, the present invention has the following configuration: [1] A polyester elastomer resin composition for foam molding, comprising as a main component a thermoplastic polyester elastomer (A) composed of hard segments made of a polyester containing as constituent components an aromatic dicarboxylic acid and an aliphatic and / or alicyclic diol, and at least one soft segment selected from aliphatic polyethers, aliphatic polyesters, and aliphatic polycarbonates, the hard segment content of which is 50 to 95 mass%, and characterized in that the composition satisfies the following (i) to (iii): (i) 10°C≦Tm−TC2≦65°C (where Tm is the melting point of the polyester elastomer resin composition, and TC2 is the temperature-lowering crystallization temperature of the polyester elastomer resin composition). (ii) η10≧1×103Pa s (iii) (η10 - η15) / η15 ≦ 1 (where η10 is the melt viscosity of the polyester elastomer resin composition measured at [melting point + 10°C], η15 is the melt viscosity of the polyester elastomer resin composition measured at [melting point + 15°C], and the melt viscosity measurement conditions are capillary diameter: 1.0 mm, capillary length: 40 mm, cylinder diameter: 9.55 mm, and shear rate: 10 / sec.) [2] The polyester elastomer resin composition for foam molding according to [1], which satisfies the following (iv): (iv) Mw / Mn≧2.5 (where Mn and Mw are the number average molecular weight and weight average molecular weight, respectively, of the polyester elastomer resin composition.) [3] The polyester elastomer resin composition for foam molding according to [1] or [2], characterized in that Mn≧35,000 and Mw / Mn≧3.5 (where Mn and Mw are the number average molecular weight and weight average molecular weight, respectively, of the polyester elastomer resin composition. [4] The polyester elastomer resin composition for foam molding according to any of [1] to [3], characterized in that the polyester elastomer resin composition contains a thickener (B), and the thickener (B) has at least one functional group (b) capable of reacting with an end group of the thermoplastic polyester elastomer (A). [5] The polyester elastomer resin composition for foam molding according to any one of [1] to [3], wherein the polyester elastomer resin composition does not contain a thickener (B) or contains it in an amount of 4.5 parts by mass or less per 100 parts by mass of the thermoplastic polyester elastomer (A), and the thickener (B) has at least one functional group (b) capable of reacting with an end group of the thermoplastic polyester elastomer (A). [6] The polyester elastomer resin composition for foam molding according to [4] or [5], wherein the functional group (b) is at least one selected from the group consisting of an epoxy group, an acid anhydride group, a carbodiimide group, and an isocyanate group.[7] The polyester elastomer resin composition for foam molding according to any one of [4] to [6], characterized in that the polyester elastomer resin composition contains, as the thickener (B), a thickener (B1) having three or more functional groups (b) in one molecule, and the content of the thickener (B1) is 1 part by mass or less per 100 parts by mass of the thermoplastic polyester elastomer (A). [8] The polyester elastomer resin composition for foam molding according to any one of [4] to [6], characterized in that the polyester elastomer resin composition contains, as the thickener (B), a thickener (B1) having three or more functional groups (b) in one molecule and a thickener (B2) having two functional groups (b) in one molecule, and the content of the thickener (B1) is 1 part by mass or less per 100 parts by mass of the thermoplastic polyester elastomer (A). [9] The polyester elastomer resin composition for foam molding according to any one of [1] to [3], wherein the polyester elastomer resin composition does not contain a thickener (B), and the thermoplastic polyester elastomer (A) has a number average molecular weight (Mn) of 35,000 or more.

[10] The polyester elastomer resin composition for foam molding according to any one of [1] to [9], wherein the thermoplastic polyester elastomer (A) has a branched structure.

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

[10] , wherein the thermoplastic polyester elastomer (A) has a hard segment content of 55% by mass or more, and wherein the amount of an isophthalic acid component is 10 mol% or less of all acid components constituting the polyester of the hard segment.

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

[11] , wherein the polyester elastomer resin composition does not contain a nucleating agent or contains a nucleating agent in an amount of less than 0.1 part by mass per 100 parts by mass of the thermoplastic polyester elastomer (A).

[13] The polyester elastomer resin composition according to any one of [1] to

[12] , which is for injection foam molding, extrusion foam molding, or batch foam molding.

[14] A foam-molded article made from the polyester elastomer resin composition for foam molding according to any one of [1] to

[13] .

[15] The foam-molded article according to

[14] , wherein the ratio (Dv / Dn) of the volume average cell diameter Dv to the number average cell diameter Dn of the foam cells of the foam-molded article is 4 or less.

[16] Use of the polyester elastomer resin composition according to any one of [1] to

[13] in foam molding.

[17] A method for producing a foam-molded article, comprising a step of foam-molding the polyester elastomer resin composition according to any one of [1] to

[13] .

[0012] The polyester elastomer resin composition for foam molding of the present invention can produce foams with improved foam cell uniformity, and preferably can produce foams with improved stability of foam cell uniformity over time. Furthermore, the polyester elastomer resin composition for foam molding of the present invention can more preferably stably produce foams that are lightweight, have high impact absorption, and are excellent in heat resistance and mechanical properties. Furthermore, the use of the thermoplastic polyester elastomer composition of the present invention is also preferred in that it enables the provision of high-quality foam molded articles by a simple molding method.

[0013] The polyester elastomer resin composition for foam molding of the present invention and the foam molded article using the same will be described in detail below.

[0014] [Thermoplastic polyester elastomer (A)] The thermoplastic polyester elastomer (A) used in the present invention is composed of a hard segment and a soft segment bonded together. The hard segment is composed of a polyester having an aromatic dicarboxylic acid and an aliphatic and / or alicyclic diol as constituent components.

[0015] As the aromatic dicarboxylic acid constituting the polyester of the hard segments, ordinary aromatic dicarboxylic acids are widely used and are not particularly limited, but examples thereof include terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, diphenyldicarboxylic acid, and 5-sodium sulfoisophthalic acid. Specific examples of naphthalenedicarboxylic acids include isomers such as 2,3-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, and 2,6-naphthalenedicarboxylic acid. Among these, the aromatic dicarboxylic acid is preferably terephthalic acid and / or naphthalenedicarboxylic acid, and more preferably terephthalic acid and / or 2,6-naphthalenedicarboxylic acid. The content of these aromatic dicarboxylic acid components is preferably 70 mol% or more, more preferably 80 mol% or more, and even more preferably 90 mol% or more, of all dicarboxylic acids constituting the polyester of the hard segments. In particular, it is preferable to adjust the content of the terephthalic acid component and the naphthalenedicarboxylic acid component within the above ranges.

[0016] The polyester may contain one or more dicarboxylic acid components other than aromatic dicarboxylic acids (hereinafter referred to as "other dicarboxylic acid components") as the acid component. Examples of other dicarboxylic acid components include alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid and tetrahydrophthalic anhydride; and aliphatic dicarboxylic acids such as succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, dimer acid, and hydrogenated dimer acid. These can be used within a range that does not significantly lower the melting point of the resin. The amount is preferably 30 mol% or less, more preferably 20 mol% or less, and may be 10 mol% or less, or 5 mol% or less, of the total acid components constituting the polyester. It is also preferable to adjust the amount of aromatic dicarboxylic acid components other than terephthalic acid and naphthalenedicarboxylic acid and other dicarboxylic acid components within the total acid components constituting the polyester to within the above range. The amount of isophthalic acid within the total acid components constituting the polyester may also be adjusted to within the above range.

[0017] The acid (component) constituting the polyester may be a single acid or a combination of two or more acids. For example, a carboxylic acid component such as a dicarboxylic acid may be introduced by ester synthesis using a carboxylic acid, a carboxylic acid ester, a carboxylic acid salt, or a carboxylic acid anhydride as a raw material.

[0018] In the thermoplastic polyester elastomer (A) used in the present invention, the aliphatic or alicyclic diol constituting the polyester hard segment is generally a general aliphatic or alicyclic diol. Examples of the aliphatic diol include, but are not limited to, aliphatic glycols such as alkylene glycols (e.g., ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, and 1,6-hexanediol). Examples of the alicyclic diol include, but are not limited to, alicyclic glycols such as 1,4-cyclohexanedimethanol and 1,4-cyclohexanediol. These diols (components) may be used alone or in combination of two or more.

[0019] The aliphatic and / or alicyclic diol (component) is not particularly limited, but is preferably an aliphatic diol, and more preferably an alkylene glycol having 2 to 8 carbon atoms. Specifically, at least one selected from ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol, and 1,4-cyclohexanedimethanol is preferred, at least one selected from ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol, and 1,4-cyclohexanedimethanol is more preferred, and either ethylene glycol or 1,4-butanediol is even more preferred.

[0020] The total content of these aliphatic and alicyclic diols (components) is preferably 70 mol % or more, more preferably 80 mol % or more, and even more preferably 90 mol % or more, of all alcohols constituting the polyester of the hard segment.

[0021] As components constituting the polyester of the hard segment, those comprising butylene terephthalate units (e.g., units composed of terephthalic acid and 1,4-butanediol) and / or butylene naphthalate units (e.g., units composed of 2,6-naphthalenedicarboxylic acid and 1,4-butanediol) are preferred from the viewpoints of physical properties, moldability, and cost performance. The content of butylene terephthalate units and butylene naphthalate units in the polyester constituting the hard segment is preferably 50 to 100% by mass, more preferably 70% by mass or more, even more preferably 80% by mass or more, and particularly preferably 90% by mass or more.

[0022] Alternatively, the thermoplastic polyester elastomer (A) used in the present invention may be produced by first preparing an aromatic polyester suitable as a polyester constituting the hard segment, and then copolymerizing it with a soft segment component. In this case, the aromatic polyester can be easily obtained according to a conventional polyester production method. Furthermore, such a polyester preferably has a number average molecular weight of 4,000 to 100,000.

[0023] The soft segment of the thermoplastic polyester elastomer (A) used in the present invention is at least one selected from aliphatic polyethers, aliphatic polyesters, and aliphatic polycarbonates. In particular, from the viewpoints of fatigue resistance to repeated deformation and low-temperature flexibility, the soft segment of the thermoplastic polyester elastomer (A) is preferably an aliphatic polyether.

[0024] Examples of the aliphatic polyether constituting the soft segment include polyethers (hereinafter referred to as poly(C )) containing one or more alkanediols having 2 to 10 carbon atoms as constituent units, such as poly(ethylene oxide) glycol, poly(propylene oxide) glycol, poly(tetramethylene oxide) glycol (sometimes called polytetramethylene glycol), poly(hexamethylene oxide) glycol, poly(trimethylene oxide) glycol, a copolymer of ethylene oxide and propylene oxide, an ethylene oxide adduct of poly(propylene oxide) glycol, and a copolymer of ethylene oxide and tetrahydrofuran. 2-10 Among these, ethylene oxide adducts of poly(tetramethylene oxide) glycol and / or poly(propylene oxide) glycol are preferred in terms of elastic properties.

[0025] The number average molecular weight of the aliphatic polyether (preferably poly(tetramethylene oxide) glycol) is preferably 500 to 4000, more preferably 800 to 3000, and even more preferably 1000 to 2500. By adjusting the number average molecular weight to the above lower limit or more, elastomeric properties are easily exhibited, and by adjusting it to the above upper limit or less, compatibility with the hard segment component is improved, making it easier to copolymerize in a block form.

[0026] Examples of the aliphatic polyester constituting the soft segment include aliphatic polyesters in which an ester group and an alkylene group having 2 to 12 carbon atoms are repeated, such as poly(ε-caprolactone), polyenantholactone, polycaprylolactone, and polybutylene adipate. Among these, poly(ε-caprolactone) and / or polybutylene adipate are preferred from the viewpoint of elastic properties.

[0027] The number average molecular weight of the aliphatic polyester is preferably 300 to 5000, more preferably 500 to 4000, and even more preferably 700 to 2500. By adjusting the number average molecular weight to the above lower limit or more, elastomeric properties are easily exhibited, and by adjusting it to the above upper limit or less, compatibility with the hard segment component is improved.

[0028] The aliphatic polycarbonate (hereinafter sometimes referred to as an aliphatic polycarbonate diol) constituting the soft segment includes a polymer composed of a carbonate unit and an aliphatic diol unit, and the aliphatic diol unit preferably consists mainly of an aliphatic diol residue having 2 to 12 carbon atoms. Examples of these aliphatic diols include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 2,2-dimethyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, 1,9-nonanediol, and 2-methyl-1,8-octanediol. In particular, from the viewpoints of the flexibility and low-temperature properties of the resulting thermoplastic polyester elastomer (A), aliphatic diols having 5 to 12 carbon atoms are preferred. These components may be used alone or in combination of two or more types as required, as in the examples described below.

[0029] From the viewpoint of improving low-temperature properties, the aliphatic polycarbonate diol constituting the soft segment of the thermoplastic polyester elastomer (A) preferably has a low melting point (for example, 70°C or lower) and a low glass transition temperature (for example, -40°C or lower). In general, an aliphatic polycarbonate diol composed of a carbonate unit and a 1,6-hexanediol unit used to form the soft segment of a thermoplastic polyester elastomer has a low glass transition temperature of about -60°C and a melting point of about 50°C, and therefore has good low-temperature properties. In addition, an aliphatic polycarbonate diol obtained by copolymerizing, for example, an appropriate amount of 3-methyl-1,5-pentanediol with the above-mentioned aliphatic polycarbonate diol has a slightly higher glass transition point than the original aliphatic polycarbonate diol, but has a lower melting point or is amorphous, and therefore corresponds to an aliphatic polycarbonate diol with good low-temperature properties. Furthermore, for example, an aliphatic polycarbonate diol composed of a carbonic acid unit, a 1,9-nonanediol unit, and a 2-methyl-1,8-octanediol unit has a melting point of about 30°C and a glass transition temperature of about -70°C, which are sufficiently low, and therefore corresponds to an aliphatic polycarbonate diol with good low-temperature properties.

[0030] The number average molecular weight of the aliphatic polycarbonate is preferably 2000 to 40000, more preferably 3000 to 20000, and even more preferably 4000 to 15000. By adjusting the number average molecular weight to be equal to or greater than the above lower limit, elastomeric properties are easily exhibited, while by adjusting it to be equal to or less than the above upper limit, compatibility with the hard segment component is improved.

[0031] The thermoplastic polyester elastomer (A) used in the present invention is particularly a terephthalic acid component and / or a 2,6-naphthalenedicarboxylic acid component, an alkylene glycol component having 2 to 8 carbon atoms, and poly(C 2-10It is preferable that the copolymer be a copolymer mainly composed of a terephthalic acid component, a 1,4-butanediol component, and a poly(tetramethylene oxide) glycol component, and it is more preferable that the copolymer be a copolymer mainly composed of a terephthalic acid component, a 1,4-butanediol component, and a poly(tetramethylene oxide) glycol component. Of the dicarboxylic acid components constituting the thermoplastic polyester elastomer (A), the terephthalic acid component and the 2,6-naphthalenedicarboxylic acid component (preferably the terephthalic acid component) preferably account for 40 mol % or more, more preferably 70 mol % or more, even more preferably 80 mol % or more, and particularly preferably 90 mol % or more. Of the glycol components constituting the thermoplastic polyester elastomer (A), it is preferable that the terephthalic acid component and the 2,6-naphthalenedicarboxylic acid component (preferably the terephthalic acid component) account for 40 mol % or more, more preferably 70 mol % or more, even more preferably 80 mol % or more, and particularly preferably 90 mol % or more. 2-10 The total of the 1,4-butanediol component and the poly(tetramethylene oxide) glycol component (preferably the total of the 1,4-butanediol component and the poly(tetramethylene oxide) glycol component) is preferably 40 mol % or more, more preferably 70 mol % or more, even more preferably 80 mol % or more, and particularly preferably 90 mol % or more.

[0032] When the hard segment content of the thermoplastic polyester elastomer (A) is greater than the soft segment content, the heat resistance and tear strength are particularly excellent. To further develop these properties, the hard segment content is preferably 40 to 95% by mass, more preferably 45 to 95% by mass, even more preferably 50 to 95% by mass, and even more preferably 55 to 95% by mass. If the hard segment content is less than 40% by mass, the crystallinity is low, resulting in poor heat resistance and tear strength, such as a low deflection temperature under load. If the hard segment content exceeds 95% by mass, the crystallinity is too high, resulting in a tendency toward permanent deformation and the destruction of independent foam cells due to repeated compression, significantly reducing sag resistance. Furthermore, if the hard segment content is less than 50% by mass, the deflection temperature under load measured in accordance with ISO 75 (0.45 MPa) is extremely low, at less than 60°C, which is undesirable.

[0033] From the viewpoint of the object of the present invention, the content of the hard segment in the thermoplastic polyester elastomer (A) of the present invention is preferably 50 to 95% by mass, and more preferably 55 to 90% by mass.

[0034] The reduced viscosity of the thermoplastic polyester elastomer (A) is preferably 1.0 to 4.0 dl / g, more preferably 1.2 to 3.7 dl / g, and may be 2.0 to 3.7 dl / g or 3.0 to 3.7 dl / g. Adjusting the reduced viscosity to equal to or greater than the lower limit of the above range tends to further improve the uniformity of foam cells, and makes it easier to adjust the melt viscosity to a desired level with the use of a small amount of thickener (B). The temperature dependence of the melt viscosity also tends to be smaller. On the other hand, adjusting the reduced viscosity to equal to or less than the upper limit of the above range increases the flowability and improves moldability in injection molding.

[0035] The thermoplastic polyester elastomer (A) used in the present invention can be produced by known methods. For example, any of melt polymerization, solution polymerization, and solid-state polymerization can be used as appropriate. In the case of melt polymerization, either transesterification or direct polymerization can be used. For example, a method in which a dicarboxylic acid component and a diol component are reacted to form a prepolymer by transesterification or direct esterification, followed by polycondensation under reduced pressure can be used. In this case, a catalyst for transesterification or esterification, or a catalyst for polycondensation can be used as appropriate. Furthermore, chain extension can be performed after polymerization using an isocyanate compound, an epoxy compound, or the like. Furthermore, solid-state polymerization can improve the viscosity (molecular weight) of the thermoplastic polyester elastomer obtained by melt polymerization or solution polymerization.

[0036] The thermoplastic polyester elastomer (A) used in the present invention preferably has a branched structure. That is, the thermoplastic polyester elastomer (A) preferably contains, as a constituent component, a compound having three or more functional groups per molecule. Such a thermoplastic polyester elastomer (A) can be produced by copolymerizing a compound having three or more functional groups per molecule during the polymerization stage. Copolymerizing the compound imparts a branched structure to the thermoplastic polyester elastomer (A), thereby restricting the movement of the polyester elastomer molecular chain at high temperatures and further suppressing a decrease in melt viscosity. Furthermore, the melt viscosity at low shear rates tends to increase, making it easier to obtain foams with smaller variations in foam cell diameter within the foam. The functional group is preferably a carboxyl group and / or a hydroxyl group. Specific examples of compounds having three or more functional groups include compounds having three or more (preferably 3 to 4) hydroxy groups, such as glycerin and pentaerythritol; and compounds having three or more (preferably 3 to 4) carboxy groups, such as trimellitic acid and pyromellitic acid; among these, compounds having three or more (preferably 3 to 4) carboxy groups are preferred. Thermoplastic polyester elastomer (A) containing a compound having three or more carboxy groups, such as trimellitic acid or pyromellitic acid, as a constituent may be produced by copolymerizing the compound directly during the polymerization stage, or by subjecting an anhydride, such as trimellitic anhydride or pyromellitic anhydride, to a copolymerization reaction. The copolymerization amount of the compound having three or more functional groups is, for example, 0 to 1 mol %, preferably 0.1 to 1 mol %, based on 100 mol % of the dicarboxylic acid component constituting the thermoplastic polyester elastomer (A).

[0037] The polyester elastomer resin composition of the present invention may contain one or more thermoplastic polyester elastomers (A).

[0038] The polyester elastomer resin composition of the present invention contains a thermoplastic polyester elastomer (A) as a main component. The content of the thermoplastic polyester elastomer (A) in the polyester elastomer resin composition is preferably 50% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and particularly preferably 95% by mass or more. The upper limit of the content is not particularly limited, and may be 100% by mass or 99.5% by mass.

[0039] [Thickener (B)] The polyester elastomer resin composition of the present invention may further contain one or more thickeners (B). The thickener (B) is preferably a reactive compound (hereinafter sometimes simply referred to as a reactive compound) having a functional group (b) capable of reacting with a terminal group (specifically, a hydroxyl group or a carboxyl group) of the thermoplastic polyester elastomer (A).

[0040] The thickener (B) preferably contains two or more of the functional groups (b) per molecule.

[0041] The functional group (b) is preferably at least one selected from an epoxy group, an acid anhydride group, a carbodiimide group, and an isocyanate group, more preferably an epoxy group, and among epoxy groups, those constituting a glycidyl group are even more preferred.

[0042] When the thickener (B) is a compound having an epoxy group, it is preferably a polyfunctional epoxy compound having two or more epoxy groups. Specific examples of polyfunctional epoxy compounds include compounds having two epoxy groups such as 1,6-dihydroxynaphthalene diglycidyl ether, 1,3-bis(oxiranylmethoxy)benzene, and polyethylene glycol diglycidyl ether; compounds having three epoxy groups such as 1,3,5-tris(2,3-epoxypropyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione and diglycerol triglycidyl ether; and compounds having four epoxy groups such as 1-chloro-2,3-epoxypropane-formaldehyde-2,7-naphthalene diol polycondensates and pentaerythritol polyglycidyl ether.

[0043] Alternatively, it is also preferable to use, as the compound having an epoxy group, a copolymer (Bp) containing two or more (preferably three or more) glycidyl groups per molecule and having a weight-average molecular weight of 4,000 to 25,000. The copolymer (Bp) is preferably a copolymer (hereinafter sometimes referred to as a styrene-based copolymer) consisting of (X) 20 to 99% by mass of a vinyl aromatic monomer, (Y) 1 to 80% by mass of an epoxy group-containing (meth)acrylate, and (Z) 0 to 79% by mass of a vinyl group-containing monomer other than (X) that does not contain an epoxy group. A styrene-based copolymer containing two or more glycidyl groups per molecule, a weight-average molecular weight of 4,000 to 25,000, and consisting of 20 to 99% by weight of a vinyl aromatic monomer (X), 1 to 80% by weight of glycidyl (meth)acrylate (Y), and 0 to 79% by weight of a vinyl group-containing monomer other than (X) that does not contain an epoxy group, is preferred because of its good compatibility with the thermoplastic polyester elastomer (A) and a broader molecular weight distribution. The copolymer (Bp) is more preferably a copolymer consisting of 20 to 99% by weight of (X), 1 to 80% by weight of (Y), and 0 to 40% by weight of (Z), and even more preferably a copolymer consisting of 25 to 90% by weight of (X), 10 to 75% by weight of (Y), and 0 to 35% by weight of (Z). These compositions affect the concentration of functional groups that contribute to the reaction with the thermoplastic polyester elastomer (A), so it is preferable to appropriately control them within the above ranges.

[0044] The vinyl aromatic monomer (X) is preferably a compound having a structure in which a vinyl group is directly bonded to an aromatic hydrocarbon ring such as a benzene ring, and specific examples thereof include styrenes which may have a substituent (for example, an alkyl group), such as styrene, α-methylstyrene, and vinyltoluene.

[0045] Examples of the (Y) epoxy group-containing (meth)acrylate include glycidyl (meth)acrylate (also referred to as glycidyl (meth)acrylate), (meth)acrylic acid esters having a cyclohexene oxide structure, and (meth)acrylic glycidyl ethers. Among these, glycidyl (meth)acrylate is preferred because of its high reactivity.

[0046] Examples of the (Z) other vinyl group-containing monomers include (meth)acrylic acid alkyl esters 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, and stearyl (meth)acrylate; (meth)acrylic acid polyalkylene glycol esters (preferably poly(C)(meth)acrylate) such as polyethylene glycol (meth)acrylate; 2-4 alkylene glycol esters); (meth)acrylic acid alkoxyalkyl esters such as methoxyethyl (meth)acrylate (preferably (meth)acrylic acid C 1-4 Alkoxy C 1-22 (meth)acrylic acid hydroxyalkyl esters (preferably (meth)acrylic acid hydroxy C) such as 2-hydroxyethyl acrylate; 1-10 (meth)acrylic acid dialkylaminoalkyl esters (preferably (meth)acrylic acid di-C alkyl esters), such as (meth)acrylic acid dimethylaminoethyl ester; 1-4 Alkylamino C 1-10 (meth)acrylic acid aralkyl esters such as (meth)acrylic acid benzyl ester (preferably (meth)acrylic acid C 7-22 aralkyl esters); (meth)acrylic acid phenoxyalkyl esters such as (meth)acrylic acid phenoxyethyl (meth)acrylate (preferably (meth)acrylic acid phenoxy C 1-10 (meth)acrylic acid isobornyl ester; (meth)acrylic acid alkoxysilyl alkyl esters such as (meth)acrylic acid 3-(trimethoxysilyl)propyl (preferably (meth)acrylic acid mono-, di-, or tri-C 1-4 Alkoxysilyl C 1-10In addition, vinyl esters such as (meth)acrylamide, (meth)acryldialkylamide, and 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 the (Z) other vinyl group-containing monomer.

[0047] The weight-average molecular weight of the copolymer (Bp) is preferably 4,000 to 25,000. The weight-average molecular weight is more preferably 5,000 to 15,000. By adjusting the weight-average molecular weight to the above-mentioned lower limit or above, it is possible to prevent unreacted copolymer (Bp) from volatilizing during the molding process or bleeding out onto the surface of the molded article, thereby causing surface contamination. On the other hand, by adjusting the weight-average molecular weight to the above-mentioned upper limit or below, the reactivity with the thermoplastic polyester elastomer (A) is enhanced, thereby further exerting the molecular weight increasing effect, and the compatibility between the copolymer (Bp) and the thermoplastic polyester elastomer (A) is improved, which tends to further improve the inherent properties of the thermoplastic polyester elastomer (A), such as heat resistance.

[0048] The epoxy value of the copolymer (Bp) is 400 to 2500 equivalents / 1×10 6 g, and more preferably 500 to 1500 equivalents / 1×10 6 g, more preferably 600 to 1000 equivalents / 1×10 6 By adjusting the epoxy value to the above lower limit or more, the thickening effect is easily exhibited, while by adjusting the epoxy value to the above upper limit or less, it is possible to prevent the thickening effect from becoming excessive, which would adversely affect moldability.

[0049] When the thickener (B) is a compound having a carbodiimide group, a polycarbodiimide compound can be used. The polycarbodiimide compound is advantageous in that it can efficiently reduce the acid value.

[0050] The polycarbodiimide compound that can be used in the present invention may be any polycarbodiimide having two or more carbodiimide groups (—N═C═N— structure) in one molecule, and examples thereof include aliphatic polycarbodiimides derived from aliphatic diisocyanates, alicyclic polycarbodiimides derived from alicyclic diisocyanates, aromatic polycarbodiimides derived from aromatic diisocyanates, and copolymers thereof. Preferred are aliphatic polycarbodiimide compounds and / or alicyclic polycarbodiimide compounds.

[0051] The polycarbodiimide compound can be obtained, for example, by the carbon dioxide removal reaction of a diisocyanate compound. Examples of diisocyanate compounds that can be used herein include aromatic diisocyanates such as 4,4'-diphenylmethane diisocyanate, 4,4'-diphenyldimethylmethane diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,5-naphthylene diisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate, and 1,3,5-triisopropylphenylene-2,4-diisocyanate; aliphatic diisocyanates such as tetramethylene diisocyanate and hexamethylene diisocyanate; and alicyclic diisocyanates such as dicyclohexylmethane diisocyanate, cyclohexane-1,4-diisocyanate, isophorone diisocyanate, and methylcyclohexane diisocyanate. These may be used alone or in the form of copolymers of two or more. A branched structure may be introduced, or a functional group other than a carbodiimide group or an isocyanate group may be introduced by copolymerization. Terminal isocyanates may be used as they are, but the degree of polymerization may be controlled by reacting the terminal isocyanates, or a portion of the terminal isocyanates may be blocked.

[0052] As the polycarbodiimide compound, alicyclic polycarbodiimides derived from dicyclohexylmethane diisocyanate, cyclohexane-1,4-diisocyanate, isophorone diisocyanate, etc. are particularly preferred, and polycarbodiimides derived from dicyclohexylmethane diisocyanate and / or isophorone diisocyanate are particularly preferred.

[0053] From the viewpoint of stability and ease of handling, it is preferable for the polycarbodiimide compound to contain 2 to 50 carbodiimide groups per molecule. More preferably, it is preferable for the polycarbodiimide compound to contain 5 to 30 carbodiimide groups per molecule. The number of carbodiimide groups in a polycarbodiimide molecule (i.e., the number of carbodiimide groups) corresponds to the degree of polymerization for polycarbodiimides obtained from diisocyanate compounds. For example, a polycarbodiimide obtained by linking 21 diisocyanate compounds in a chain has a degree of polymerization of 20, and the number of carbodiimide groups in the molecular chain is 20. Polycarbodiimide compounds are typically mixtures of molecules of various lengths, and the number of carbodiimide groups is expressed as an average value. A polycarbodiimide compound having the number of carbodiimide groups within the above range and being solid at or near room temperature can be powdered, resulting in excellent workability and compatibility when mixed with the thermoplastic polyester elastomer (A), and is also preferable in terms of uniform reactivity and bleed-out resistance. The number of carbodiimide groups can be measured, for example, by a conventional method (a method in which a compound is dissolved in an amine and then back-titrated with hydrochloric acid).

[0054] From the viewpoint of stability and ease of handling, the polycarbodiimide compound preferably has an isocyanate group at its terminal, and the isocyanate group content is preferably 0.5 to 4% by mass. More preferably, the isocyanate group content is 1 to 3% by mass. In particular, polycarbodiimides derived from alicyclic diisocyanates such as dicyclohexylmethane diisocyanate and isophorone diisocyanate and having an isocyanate group content within the above range are preferred. The isocyanate group content can be measured using a standard method (for example, a method in which the compound is dissolved in an amine and then back-titrated with hydrochloric acid).

[0055] When the thickener (B) is a compound having an isocyanate group, examples thereof include the above-mentioned polycarbodiimide compounds containing an isocyanate group and the above-mentioned isocyanate compounds that are raw materials for polycarbodiimide compounds.

[0056] When the thickener (B) is a compound having an acid anhydride group, a compound containing 2 to 4 anhydrides per molecule is preferred in terms of stability and ease of handling. Examples of such compounds include phthalic anhydride, trimellitic anhydride, and pyromellitic anhydride.

[0057] In the present invention, when a thermoplastic polyester elastomer (A) that exhibits the effects of the present invention is used, the thickener (B) is not an essential component, i.e., the polyester elastomer resin composition of the present invention does not need to contain the thickener (B).

[0058] When a thickener (B) is contained, its content is, for example, 4.5 parts by mass or less, preferably 0.1 to 4.5 parts by mass, more preferably 0.1 to 4 parts by mass, even more preferably 0.1 to 3 parts by mass, particularly preferably 0.1 to 2 parts by mass, and most preferably 0.1 to 1 part by mass, per 100 parts by mass of the thermoplastic polyester elastomer (A). When a thickener (B) is required, adjusting the amount of thickener (B) to above the above-mentioned lower limit tends to achieve the desired molecular chain extension effect, while adjusting it to below the above-mentioned upper limit can prevent excessive thickening effect, which could adversely affect moldability or the mechanical properties of the molded product. In particular, when the thickener (B) is an epoxy compound having an epoxy group as the functional group (b), adjusting its content to below the above-mentioned upper limit can prevent the occurrence of surface irregularities in the molded product due to aggregation and curing of the epoxy compound. Furthermore, when the thickener (B) is a carbodiimide compound having a carbodiimide group as the functional group (b), adjusting the content thereof to the above-mentioned upper limit or less can suppress hydrolysis of the thermoplastic polyester elastomer (A) due to the basicity of the polycarbodiimide compound, which can adversely affect the mechanical properties.

[0059] In particular, the polyester elastomer resin composition of the present invention preferably contains, as the thickener (B), a thickener (B1) having three or more functional groups (b) per molecule. The use of the thickener (B1) reacts with the thermoplastic polyester elastomer (A) to introduce branches into the polymer, making it easier to satisfy the formula (iii) described below.

[0060] The thickener (B1) is preferably a thickener having three or more epoxy groups in one molecule, and more preferably the above-mentioned copolymer (Bp).

[0061] The content of the thickener (B1) can be adjusted appropriately depending on the thermoplastic polyester elastomer (A) used. The content of the thickener (B1) is preferably 1 part by mass or less, more preferably 0.9 parts by mass or less, even more preferably 0.8 parts by mass or less, and even more preferably 0.6 parts by mass or less, per 100 parts by mass of the thermoplastic polyester elastomer (A). The lower limit of the content of the thickener (B1) is preferably 0.1 parts by mass. By using the above content of the thickener (B1), an appropriate amount of branching is achieved, enabling stable production of foamed molded articles with high expansion ratios and uniform foam cells over a long period of time. In particular, adjusting the content of the thickener (B1) to the above upper limit or less suppresses multiple reactions between the same polyester elastomer molecule or nearby molecules, facilitating an increase in the molecular weight of the thermoplastic polyester elastomer resin composition. Furthermore, gelation can be suppressed.

[0062] The polyester elastomer resin composition of the present invention preferably contains, as the thickener (B), a thickener (B2) having two functional groups (b) per molecule. The thickener (B2) is less likely to undergo multiple reactions with the same polyester elastomer molecule or with neighboring molecules, making it easier to control the molecular weight of the polyester elastomer resin composition and adjust the melt viscosity to satisfy the formula (ii) described below.

[0063] The thickener (B2) is preferably a compound having two epoxy groups, more preferably a compound having two glycidyl groups, and even more preferably a compound having two glycidyl groups bonded to an aromatic hydrocarbon ring via an ether bond (e.g., 1,6-dihydroxynaphthalene diglycidyl ether, 1,3-bis(oxiranylmethoxy)benzene) and / or a compound having two glycidyl groups bonded to a polyalkylene glycol via an ether bond (e.g., polyethylene glycol diglycidyl ether).

[0064] The content of the thickener (B2) may be adjusted appropriately depending on the thermoplastic polyester elastomer (A) used, but is preferably 5 parts by mass or less, more preferably 3 parts by mass or less, even more preferably 1 part by mass or less, and even more preferably 0.6 parts by mass or less, relative to 100 parts by mass of the thermoplastic polyester elastomer (A). The lower limit of the content of the thickener (B2) is preferably 0.1 parts by mass.

[0065] It is also preferable to use the thickener (B1) and the thickener (B2) in combination as the thickener (B). In this case, the preferred contents of the thickener (B1) and the thickener (B2) are the same as those described above.

[0066] It is particularly preferable that the polyester elastomer resin composition of the present invention satisfies any one of the following aspects A to C. Aspect A: As the thickener (B), a thickener (B1) and a thickener (B2) are used in combination. Aspect B: The thickener (B) is not contained, and the number average molecular weight (Mn) of the thermoplastic polyester elastomer (A) is 35,000 or more. Aspect C: The thermoplastic polyester elastomer (A) having a branched structure is contained.

[0067] In Aspect B, the Mn of the thermoplastic polyester elastomer (A) is preferably 35,000 to 100,000, and more preferably 40,000 to 100,000. In Aspect B, the molecular weight distribution (Mw / Mn) of the thermoplastic polyester elastomer (A) is preferably 3.0 to 10.0, more preferably 3.5 to 9.0, and even more preferably 3.8 to 8.5.

[0068] In the above-mentioned aspect C, the branched structure of the thermoplastic polyester elastomer (A) can be produced by copolymerizing a compound having three or more functional groups in one molecule during the polymerization stage, as described above. In the above-mentioned aspect C, the polyester elastomer resin composition may or may not contain a thickener (B), but it is preferable that it contains a thickener (B). In particular, it is preferable that it contains a thickener (B2). The preferred content of the thickener (B2) is the same as above.

[0069] [Stabilizer] The polyester elastomer resin composition of the present invention preferably contains a stabilizer such as an antioxidant based on an aromatic amine, a hindered phenol, a sulfur-based or a phosphorus-based, or a light stabilizer based on a hindered amine, a benzotriazole, a benzophenone, a benzoate, a triazole, a nickel, a salicylic acid, etc. These may be used alone or in combination of two or more.

[0070] Specific examples of the aromatic amine antioxidant used in the polyester elastomer resin composition of the present invention include phenylnaphthylamine, 4,4'-dimethoxydiphenylamine, 4,4'-bis(α,α-dimethylbenzyl)diphenylamine, and 4-isopropoxydiphenylamine.

[0071] Examples of hindered phenol antioxidants include 3,5-di-t-butyl-4-hydroxy-toluene, n-octadecyl-β-(4'-hydroxy-3',5'-di-t-butylphenyl)propionate, tetrakis[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane, 1,3,5-trimethyl-2,4,6'-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene, calcium(3,5-di-t-butyl-4 -hydroxy-benzyl-monoethyl-phosphate), triethylene glycol-bis[3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate], pentelityl-tetrakis[3-(3,5-di-t-butylanilino)-1,3,5-triazine, 3,9-bis[1,1-dimethyl-2-{β-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy}ethyl]2,4,8,10-tetraoxaspiro[5,5]undecane, Bis[3,3-bis(4'-hydroxy-3'-t-butylphenyl)butyric acid] glycol ester, 2,2'-ethylidenebis(4,6-di-t-butylphenol), N,N'-bis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyl]hydrazine, 2,2'-oxamidobis[ethyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], 1,1,3-tris(3',5'-di-t-butyl-4'-hydroxybenzyl)-S- Examples include triazine-2,4,6(1H,3H,5H)-trione, 1,3,5-tris(4-t-butyl-3-hydroxy-2,6-dimethylbenzyl)isocyanurate, 3,5-di-t-butyl-4-hydroxyhydrocinnamic amide triester with-1,3,5-tris(2-hydroxyethyl)-S-triazine-2,4,6(1H,3H,5H), and N,N-hexamethylenebis(3,5-di-t-butyl-4-hydroxy-hydrocinnaamide).

[0072] Examples of phosphorus-based antioxidants include phosphorus-containing compounds such as phosphoric acid, phosphorous acid, hypophosphorous acid derivatives, phenylphosphonic acid, polyphosphonates, and diphosphite compounds. Specific examples include triphenyl phosphite, diphenyldecyl phosphite, phenyl diisodecyl phosphite, tri(nonylphenyl)phosphite, bis(2,4-di-t-butylphenyl)pentaerythritol diphosphite, and bis(2,6-di-t-butyl-4-methylphenyl)pentaerythritol diphosphite.

[0073] Examples of sulfur-based antioxidants include sulfur-containing compounds such as thioethers, dithioacid salts, mercaptobenzimidazoles, thiocarbanilides, and thiodipropionates. Specific examples include dilauryl thiodipropionate, distearyl thiodipropionate, didodecyl thiodipropionate, ditetradecyl thiodipropionate, dioctadecyl thiodipropionate, pentaerythritol tetrakis(3-dodecylthiopropionate), thiobis(N-phenyl-β-naphthylamine), 2-mercaptobenzothiazole, 2-mercaptobenzimidazole, tetramethylthiuram monosulfide, tetramethylthiuram disulfide, nickel dibutyldithiocarbamate, nickel isopropyl xanthate, and trilauryl trithiophosphite.

[0074] Examples of hindered amine light stabilizers include polycondensates of dimethyl succinate and 1-(2-hydroxyethyl)-4-hydroxy-2,2,6,6-tetramethylpiperidine, poly[[6-(1,1,3,3-tetrabutyl)imino-1,3,5-triazine-2,4-diyl]hexamethylene[(2,2,6,6-tetramethyl-4-piperidyl)imyl]], and bis(1,2,2,6,6-pentamethyl-4-piperidyl) of 2-n-butylmalonic acid. Ester, tetrakis(2,2,6,6-tetramethyl-4-piperidyl)-1,2,3,4-butanetetracarboxylate, bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate, polycondensation product of N,N'-bis(2,2,6,6-tetramethyl-4-piperidyl)hexamethylenediamine and 1,2-dibromoethane, poly[(N,N'-bis(2,2,6,6-tetramethyl-4-piperidyl) hexamethylenediamine)-(4-monofolino-1,3,5-triazine-2,6-diyl)-bis(3,3,5,5-tetramethylpiperazinone)], tris(2,2,6,6-tetramethyl-4-piperidyl)-dodecyl-1,2,3,4-butanetetracarboxylate, tris(1,2,2,6,6-pentamethyl-4-piperidyl)-dodecyl-1,2,3,4-butanetetracarboxylate, bis(1 ,2,2,6,6-pentamethyl-4-piperidyl)sebacate, 1,6,11-tris[{4,6-bis(N-butyl-N-(1,2,2,6,6-pentamethylpiperidin-4-yl)amino-1,3,5-triazin-2-yl)amino}undecane, 1-[2-(3,5-di-t-butyl-4-hydroxyphenyl)propionyloxy]-2,2,6,6-tetramethylpiperidine, 8-benzyl-7,7 ,9,9-tetramethyl-3-octyl-1,3,8-triazaspiro[4,5]undecane-2,4-dione, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, N,N'-bis(3-aminopropyl)ethylenediamine-2,4-bis[N-butyl-N-(1,2,2,6,6-pentamethyl-4-piperidyl)amino]-6-chloro-1,3,5-triazine condensate, and the like can be mentioned.

[0075] Benzophenone, benzotriazole, benzoate, triazole, nickel, and salicylic light stabilizers include 2,2'-dihydroxy-4-methoxybenzophenone, 2-hydroxy-4-n-octoxybenzophenone, p-t-butylphenyl salicylate, 2,4-di-t-butylphenyl-3,5-di-t-butyl-4-hydroxybenzoate, 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-3',5'-di-t-butylphenyl)benzotriazole, and 2-(2'-hydroxy-5'-methylphenyl)benzotriazole. 2-[2'-hydroxy-3',5'-bis(α,α-dimethylbenzylphenyl)benzotriazole, 2-(2'-hydroxy-3'-t-butyl-5'-methylphenyl)-5-chlorobenazotriazole, 2-(2'-hydroxy-3',5'-di-t-butylphenyl)-5-chlorobenzothiazole, 2,5-bis-[5'-t-butylbenzoxazolyl-(2)]-thiophene, bis(3,5-di-t-butyl-4-hydroxybenzylphosphoric acid), acid monoethyl ester) nickel salt, a mixture of 85-90% 2-ethoxy-5-t-butyl-2'-ethyloxalic acid bis-anilide and 10-15% 2-ethoxy-5-t-butyl-2'-ethyl-4'-t-butyloxalic acid bis-anilide, 2-[2-hydroxy-3,5-bis(α,α-dimethylbenzyl)phenyl]-2H-benzotriazole, 2-ethoxy-2'-ethyloxalic acid bis-anilide, 2-[2'-hydroxy-5'-methyl-3 Examples of light stabilizers include 2-(2'-hydroxy-5'-t-octylphenyl)benzotriazole, bis(5-benzoyl-4-hydroxy-2-methoxyphenyl)methane, 2-(2'-hydroxy-5'-t-octylphenyl)benzotriazole, 2-hydroxy-4-i-octoxybenzophenone, 2-hydroxy-4-dodecyloxybenzophenone, 2-hydroxy-4-octadecyloxybenzophenone, and phenyl salicylate.

[0076] The blending (content) amount of each of the antioxidants and / or light stabilizers is preferably 0.01 to 3 parts by mass, more preferably 0.05 to 2 parts by mass, and even more preferably 0.1 to 1 part by mass, per 100 parts by mass of the thermoplastic polyester elastomer (A). When two or more types of antioxidants and / or light stabilizers are blended, the upper limit of the total content is preferably 5 parts by mass.

[0077] In the present invention, a composition containing the thermoplastic polyester elastomer (A) and other components (specifically, a thickener (B), an antioxidant, a light stabilizer and / or an additive described below) is referred to as a thermoplastic polyester elastomer resin composition. However, when the thermoplastic polyester elastomer (A) alone can exhibit the effects of the present invention, it may also be referred to as a polyester elastomer resin composition for convenience.

[0078] [Other Additives] In addition to the antioxidants and light stabilizers, various additives may be blended into the thermoplastic polyester elastomer (A) used in the present invention depending on the intended purpose. The types of such additives are not particularly limited, and various additives commonly used in foam molding can be used. Specific examples of additives include lubricants, fillers, flame retardants, flame retardant auxiliaries, release agents, antistatic agents, molecular regulators such as peroxides, metal deactivators, organic and / or inorganic nucleating agents, neutralizing agents, antacids, antibacterial agents, fluorescent brighteners, organic and / or inorganic pigments, and organic and / or inorganic phosphorus compounds used to impart flame retardancy or thermal stability. The additives may be used alone or in combination of two or more. When additives are added, their content (total content when multiple additives are used) is preferably 30% by mass or less, more preferably 20% by mass or less, even more preferably 10% by mass or less, and particularly preferably 5% by mass or less, of the polyester elastomer resin composition.

[0079] When the polyester elastomer resin composition contains an organic and / or inorganic nucleating agent (specifically, a crystal nucleating agent), the value of Tm-TC2, which will be described later, tends to be small.

[0080] Examples of the organic nucleating agent include metal salts of organic carboxylic acids having 3 to 40 carbon atoms, and specific examples include alkali metal salts (e.g., sodium salts, potassium salts, and lithium salts) of aliphatic carboxylic acids such as propionic acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, lauric acid, myristic acid, palmitic acid, margaric acid, stearic acid, oleic acid, linoleic acid, and montanic acid.

[0081] Examples of the inorganic nucleating agent include inorganic particles, such as talc, silica, zeolite, alkaline earth metal carbonates (e.g., calcium carbonate, magnesium carbonate), barium sulfate, metal oxides (e.g., zinc oxide, titanium oxide, alumina), metal hydroxides (e.g., aluminum hydroxide, potassium hydroxide, calcium hydroxide, magnesium hydroxide), metals (e.g., iron, copper, aluminum, nickel, zinc, titanium), mica, clays such as montmorillonite (particularly hard clays), carbon particles, glass fibers, carbon tubes, and layered silicates. The inorganic nucleating agent may be surface-treated or may be silane-coupling-treated with aminosilane, mercaptosilane, vinylsilane, or the like. The shape of the inorganic nucleating agent is not limited, and it may be in powder form.

[0082] The content of the nucleating agent may be adjusted appropriately depending on the type of thermoplastic polyester elastomer (A) used, and may be, for example, 0 to 5.0 parts by mass. However, it is preferably 0 to 1.0 part by mass (particularly less than 0.1 part by mass), more preferably 0 to 0.5 part by mass, and even more preferably does not contain a nucleating agent.

[0083] The composition and composition ratio of the polyester elastomer resin composition used in the present invention can be determined by dissolving a sample in a solvent such as deuterated chloroform and measuring the composition. 1 It can also be calculated from the proton integral ratio of H-NMR.

[0084] [Characteristics of Polyester Elastomer Resin Composition] The melting point (Tm) and cooling crystallization temperature (TC2) of the polyester elastomer resin composition of the present invention, as measured by a differential scanning calorimeter (DSC), satisfy the following formula (i): (i) 10°C≦Tm−TC2≦65°C. The melting point (Tm) and cooling crystallization temperature (TC2) referred to in the present invention are values ​​obtained in accordance with ASTM D-3418. Specifically, the cooling crystallization temperature (TC2) is measured using a differential scanning calorimeter (DSC) by heating the composition to 250°C at a heating rate of 20°C / min under a nitrogen stream, holding the composition at that temperature for 2 minutes, and then cooling the composition to 50°C at a rate of 20°C / min. If the formula (i) is less than 10°C, crystallization proceeds rapidly, resulting in a significant temperature dependency of the melt viscosity and making it impossible to obtain a stable foamed molded article. For example, the foam cell size tends to vary over time and depending on the location in the foamed molded article. Furthermore, the appearance of the molded product is also deteriorated. On the other hand, if the value of the formula (i) is greater than 65°C, the solidification rate becomes too slow, and the molding cycle becomes significantly longer. The Tm-TC2 value is preferably 15 to 65°C, and more preferably 20 to 60°C.

[0085] Tm-TC2 can be reduced, for example, by increasing the ratio of hard segments in the thermoplastic polyester elastomer (A), using a nucleating agent as an additive, etc. Furthermore, a method of reducing the crystallinity of the thermoplastic polyester elastomer (A), such as copolymerizing isophthalic acid, can be used as a means of increasing Tm-TC2.

[0086] The polyester elastomer resin composition of the present invention has a melt viscosity measured at temperatures of melting point of resin composition + 10°C and melting point + 15°C, a capillary diameter of 1.0 mm, a capillary length of 40 mm, a cylinder diameter of 9.55 mm, and a shear rate of 10 / sec, which satisfy the following formulas (ii) and (iii): (ii) η10≧1×10 3Pa s (iii)(η10-η15) / η15≦1 (where η10 is the melt viscosity of the polyester elastomer resin composition measured at [melting point + 10°C], η15 is the melt viscosity of the polyester elastomer resin composition measured at [melting point + 15°C], and the melt viscosity measurement conditions are capillary diameter: 1.0 mm, capillary length: 40 mm, cylinder diameter: 9.55 mm, and shear rate: 10 / sec.) By controlling the melt viscosity within this range, the effect of the resin composition temperature during foam molding is reduced, and foam molded articles with high expansion ratio and uniform foam cells can be stably produced over an extended period of time.

[0087] In the formula (i), the value of η is 1×10 3 Pa s ~ 30 x 10 3 Pa s, and preferably 1.2 × 10 3 Pa s ~ 20 x 10 3 Pa s is more preferable, and 1.8×10 3 Pa s to 10 x 10 3 It is more preferable that the value of η is 1.2×10 Pa·s. 3 By adjusting the viscosity to Pa s or more, the foam cell uniformity and the stability of foam cell uniformity over time (particularly the stability over time) can be further improved. Furthermore, by adjusting the value of η to the above upper limit or less, the temperature dependency can be easily suppressed.

[0088] In the formula (iii), the value of (η10-η15) / η15 is preferably 0.8 or less, more preferably 0.6 or less, and even more preferably 0.5 or less. The lower limit of the value of (η10-η15) / η15 is not particularly limited, and may be, for example, about 0.1.

[0089] While there are no particular limitations on the method for controlling the formulas (ii) and (iii) within the predetermined range, it is preferable to increase the molecular weight of the polyester elastomer resin composition. Specifically, the number average molecular weight (Mn) is, for example, 16,000 or more, preferably 25,000 or more, more preferably 30,000 or more, even more preferably 35,000 or more, and even more preferably 40,000 or more. Furthermore, it is preferable that the polyester elastomer in the polyester elastomer resin composition is crosslinked or branched. The crosslinked moieties or branches restrict the movement of the polyester elastomer molecular chain at high temperatures and suppress a decrease in melt viscosity. The crosslinked moieties or branches can be introduced by using a thickener (B) or copolymerizing a compound having three or more functional groups per molecule during the polymerization stage of the thermoplastic polyester elastomer (A). The upper limit of Mn of the polyester elastomer resin composition is not particularly limited, but is, for example, 150,000 or less.

[0090] The polyester elastomer resin composition of the present invention preferably satisfies the following formula (iv): (iv) Mw / Mn≧2.5, where Mn and Mw are the number-average molecular weight and weight-average molecular weight, respectively, of the polyester elastomer resin composition obtained by gel permeation chromatography (GPC). Detailed measurement conditions for GPC are as described in the Examples section. By controlling the molecular weight distribution so that Mw / Mn satisfies formula (iv), the temperature dependence of the melt viscosity becomes smaller, making it easier to obtain stable foam-molded products. The Mw / Mn is preferably 2.5 to 10, more preferably 3.0 to 9.5, even more preferably 3.5 to 9.0, and particularly preferably 3.8 to 8.5.

[0091] The polyester elastomer resin composition of the present invention can achieve formulas (ii) and (iii) without crosslinking or branching using a thickener (B) or the like. To satisfy formulas (ii) and (iii), the polyester elastomer resin composition preferably has Mn≧35,000 and Mw / Mn≧3.5, more preferably Mn≧40,000 and Mw / Mn≧4.0, and even more preferably Mn≧50,000 and Mw / Mn≧5.0. The upper limit of Mn is not particularly limited, but is, for example, 150,000 or less, and the upper limit of Mw / Mn is also not particularly limited, but is, for example, 10 or less. For example, by producing the thermoplastic polyester elastomer (A) by solid-state polymerization, a polyester elastomer resin composition within the above ranges can be prepared without using a thickener (B). However, the thermoplastic polyester elastomer (A) obtained by solid-phase polymerization has few terminal acid groups that react with the functional group (b) of the thickener (B), making it difficult to control the resin properties after polymerization.

[0092] [Pellets of Polyester Elastomer Resin Composition] Pellets formed from the polyester elastomer resin composition of the present invention are also encompassed by the present invention. Known methods can be used to produce pellets. For example, the polyester elastomer resin composition can be melt-kneaded using a single- or twin-screw melt kneader or a conventional thermoplastic elastomer mixer, such as a kneader-type heater, followed by pelletization using a known granulation process. The pellets of the present invention preferably satisfy the above requirements (i) to (iii) (preferably (i) to (iv)). The preferred values ​​of Tm-TC2, η10, η10-η15, and Mw / Mn of the pellets of the present invention are the same as those described for the polyester elastomer resin composition.

[0093] [Foam Molded Article] A foam molded article can be produced from the polyester elastomer resin composition of the present invention by a production method including a step of foam molding the polyester elastomer resin composition (hereinafter referred to as the foam molding step).

[0094] The foam molding step (a foaming method for a polyester elastomer resin composition) is not particularly limited, and examples thereof include a method of adding a chemical foaming agent and / or a physical foaming agent to a polyester elastomer resin composition and then foaming it, and a method of preforming a polyester elastomer resin composition, impregnating a preformed body obtained by preforming the polyester elastomer resin composition with a physical foaming agent, and then foaming it. Among these, it is preferable to include a foaming step (a method) of impregnating a polyester elastomer resin composition or a preformed body of the polyester elastomer resin composition with a high-pressure gas (preferably an inert gas in a supercritical state), and then reducing the pressure (releasing the pressure).

[0095] The chemical foaming agent that can be used to obtain the foamed molded article of the present invention is preferably one that is added to a molten resin (specifically, a polyester elastomer resin composition molten in the resin melting zone of a molding machine) as a gas component that serves as a foam nucleus or as a source of that gas. Specifically, the chemical foaming agent can be an inorganic compound such as ammonium carbonate or sodium bicarbonate, or an organic compound such as an azo compound, a sulfohydrazide compound, a nitroso compound, or an azide compound. Examples of the azo compound include diazocarbonamide (ADCA), 2,2-azoisobutyronitrile, azohexahydrobenzonitrile, and diazoaminobenzene, with ADCA being the most preferred. Examples of the sulfohydrazide compound include benzenesulfohydrazide, benzene 1,3-disulfohydrazide, diphenylsulfone-3,3-disulfonhydrazide, and diphenyloxide-4,4-disulfonhydrazide. Examples of the nitroso compound include N,N-dinitrosopentaethylenetetramine (DNPT) and N,N-dimethyl terephthalate. Examples of the azide compound include terephthalazide and p-tert-butylbenzazide.

[0096] When a chemical blowing agent is used as the blowing agent, the chemical blowing agent can be uniformly dispersed in the polyester elastomer resin composition of the present invention by using a blowing agent masterbatch based on a thermoplastic resin having a melting point lower than the decomposition temperature of the chemical blowing agent. 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). In this case, the blending ratio of the chemical blowing agent to the thermoplastic resin is preferably 10 to 100 parts by mass of the chemical blowing agent per 100 parts by mass of the thermoplastic resin. By using 10 parts by mass or more of the chemical blowing agent, it is possible to prevent a deterioration in physical properties due to an excessive amount of masterbatch relative to the polyester elastomer resin composition of the present invention. Furthermore, by adjusting the amount to 100 parts by mass or less, the dispersibility of the chemical blowing agent is improved, facilitating the preparation of the masterbatch.

[0097] The physical foaming agent may be an inert gas, and particularly a supercritical inert gas is preferred. When an inert gas (preferably a supercritical inert gas) is used as the foaming agent, it is preferred to use carbon dioxide and / or nitrogen as the inert gas.

[0098] Here, the term "supercritical state" refers to a state in which, when the temperature and pressure of a substance that exists in a gas phase and a liquid phase are increased, the distinction between the gas phase and the liquid phase can be eliminated within a certain temperature and pressure range, and the temperature and pressure at this point are called the critical temperature and critical pressure. That is, in a supercritical state, a substance has the properties of both a gas and a liquid, and the fluid that occurs in this state is called a critical fluid. Such a critical fluid has a higher density than a gas and a lower viscosity than a liquid, and therefore has the property of being extremely easy to diffuse within a substance.

[0099] When a physical blowing agent (preferably carbon dioxide and / or nitrogen in a supercritical state) is used as the blowing agent, the amount thereof is preferably 0.05 to 30 parts by mass, and more preferably 0.1 to 20 parts by mass, per 100 parts by mass of the polyester elastomer resin composition of the present invention. By adjusting the amount of the physical blowing agent (preferably carbon dioxide and / or nitrogen in a supercritical state) to be equal to or greater than the above lower limit, uniform and fine foam cells are more likely to be obtained, while by adjusting it to be equal to or less than the above upper limit, a molded article with a good surface appearance tends to be obtained.

[0100] The physical foaming agent (preferably carbon dioxide or nitrogen in a supercritical state) used as the foaming agent can be used alone, or a mixture of two or more inert gases (for example, carbon dioxide and nitrogen) can be used. Nitrogen tends to be suitable for forming finer cells in a polyester elastomer resin composition, while carbon dioxide is suitable for obtaining a higher expansion ratio because it allows a relatively larger amount of gas to be injected. Therefore, these may be mixed as desired depending on the state of the foamed structure prepared, and when mixed, the mixing ratio (carbon dioxide:nitrogen) is preferably in the range of 1:9 to 9:1 in molar ratio.

[0101] As the foaming agent used in the present invention, from the viewpoint of uniform fine foaming, a physical foaming agent is preferred, an inert gas in a supercritical state is more preferred, and nitrogen in a supercritical state is even more preferred.

[0102] When the foaming agent is added, the polyester elastomer resin composition is preferably plasticized, i.e., the polyester elastomer resin composition and the foaming agent are preferably melt-kneaded and then foam-molded.

[0103] Known methods can be used for foam molding. Among these, injection foam molding, extrusion foam molding, or batch foam molding is preferred, with injection foam molding or extrusion foam molding being more preferred, and injection foam molding being even more preferred. Among injection foam molding methods, a preferred method, which offers advantages in molding cycle time, cost, and homogeneous foaming, is to melt-mix a blowing agent and the polyester elastomer resin composition of the present invention and then injection-molde the resulting mixture to expand the cavity volume, thereby obtaining a foam-molded article. Specifically, this method involves injecting a molten polyester elastomer resin composition into a cavity formed by clamping multiple molds together with a chemical blowing agent and / or a supercritical inert gas (hereinafter sometimes collectively referred to as "blowing agent"), filling the cavity, and then moving at least one mold in the mold-opening direction to expand the cavity volume, thereby obtaining a foam-molded article (mold expansion method). Specifically, after filling the cavity with the polyester elastomer resin composition and the blowing agent, the cavity is cooled to a predetermined temperature, and the mold is moved in the mold-opening direction to expand the cavity volume. The polyester elastomer resin composition for foam molding and the blowing agent can be mixed in the plasticizing zone of the injection molding machine before filling the cavity. The preferred embodiments of the blowing agent are as described above. The foam molded article of the present invention preferably has a sandwich structure in which non-foamed skin layers are provided on both sides of a foam layer (in other words, a structure in which a foam layer is sandwiched between non-foamed skin layers on both sides). There are no particular limitations on the size of the foam molded article, but the thickness of the sandwich structure is expected to be about 1 to 30 mm.

[0104] The non-foamed skin layer is laminated on the foamed layer and has a thickness of preferably 100 to 800 μm, more preferably 200 to 600 μm, and even more preferably 300 to 400 μm. By adjusting the thickness of the non-foamed skin layer to the above lower limit or more, a good appearance tends to be obtained. On the other hand, by adjusting the thickness to the above upper limit or less, the specific gravity of the foamed layer increases, resulting in a density of 0.01 to 0.45 g / cm3 as described below for the entire foamed molded article. 3 This tends to result in a foam structure with uniform cells.

[0105] To inject a molten polyester elastomer resin composition into a cavity together with a blowing agent, the molten polyester elastomer resin composition and the blowing agent may be mixed in the plasticizing zone of an injection molding machine. In particular, when supercritical carbon dioxide and / or nitrogen are used as the blowing agent, a method of injecting gaseous carbon dioxide and / or nitrogen directly from a gas cylinder or pressurized with a booster pump into the injection molding machine can be employed. From the viewpoint of solubility, permeability, and diffusibility in the molten polyester elastomer resin composition, it is preferable that the carbon dioxide and / or nitrogen be in a supercritical state inside the molding machine.

[0106] The foam layer is composed of a resin continuous phase and independent foam cells. Here, the resin continuous phase refers to the non-void portion formed by the cured polyester elastomer resin composition. It is preferable that the diameter (cell diameter) of the foam cells in the foam molded article be uniform and consistent. The average cell diameter (preferably the number average cell diameter) is preferably 10 to 400 μm, more preferably 50 to 400 μm, even more preferably 100 to 400 μm, and particularly preferably 150 to 300 μm. By adjusting the average cell diameter to above the lower limit, the internal pressure of the molded article is high, the pressure during the formation of the non-foamed skin layer is sufficient, and deterioration of the appearance, such as sink marks, tends to be suppressed. On the other hand, by adjusting the average cell diameter to below the upper limit, the load-bearing capacity tends to be improved.

[0107] The foamed molded article of the present invention has a small variation in foam cell diameter. The ratio of the volume average cell diameter Dv to the number average cell diameter Dn (Dv / Dn) of the foamed cells of the foamed molded article of the present invention is, for example, 4 or less, preferably 1.0 to 4.0, more preferably 1.0 to 3.0, even more preferably 1.0 to 2.0, and particularly preferably 1.1 to 1.7. The methods for measuring Dv and Dn are as described in the Examples below.

[0108] The density of the foamed molded body is 0.01 to 0.45 g / cm 3 is preferably 0.1 to 0.4 g / cm 3The density of a typical polyester elastomer is about 1.0 to 1.4 g / cm 3 Since the density is around 0.01 to 0.35 g / cm3, it can be said that the weight is sufficiently reduced if it is within the above range. If the density is equal to or higher than the above lower limit, sufficient strength is obtained and the mechanical properties tend to be improved, and if it is equal to or lower than the above upper limit, it can be said that sufficient flexibility is obtained and the weight is also sufficiently reduced. In order to achieve both light weight, excellent strength, and impact absorption, the density of the foamed molded product is 0.01 to 0.35 g / cm3. 3 It is particularly preferred that:

[0109] The foamed molded article of the present invention is formed from the polyester elastomer resin composition described above, and therefore can achieve excellent impact absorption properties and light weight.

[0110] This application claims the benefit of priority based on Japanese Patent Application No. 2024-052382, filed on March 27, 2024. The entire contents of the specification of Japanese Patent Application No. 2024-052382, filed on March 27, 2024, are incorporated herein by reference.

[0111] In the following examples and comparative examples, the following raw materials were used.

[0112] <Thermoplastic Polyester Elastomer (A)> (Polyester Elastomer A-1) 845 parts by mass of dimethyl terephthalate, 528 parts by mass of 1,4-butanediol, 672 parts by mass of polytetramethylene glycol (number average molecular weight 1000), 1.4 parts by mass of Irganox 1330 (manufactured by Ciba Specialty Chemicals), and 0.6 parts by mass of tetrabutyl titanate were charged, and the temperature was raised from room temperature to 210°C over 2 hours, and then heated at 210°C for 1 hour to carry out a transesterification reaction. The pressure inside the vessel was then gradually reduced and the temperature was raised, and the pressure was lowered to 245°C and 130 Pa or less over 50 minutes to carry out an initial polymerization reaction. The polymerization reaction was further carried out for 2.5 hours at 245°C and 130 Pa or less, and the resulting molten polyester resin was withdrawn in the form of strands from a discharge port at the bottom of the polymerization vessel, cooled in a water bath, and then cut into chips to obtain Polyester Elastomer A-1. The hard segment content was 52% by mass, and the reduced viscosity was 1.8 dl / g.

[0113] (Polyester Elastomer A-2) 970 parts by mass of dimethyl terephthalate, 657 parts by mass of 1,4-butanediol, 423 parts by mass of polytetramethylene glycol (number average molecular weight 1000), 1.4 parts by mass of Irganox 1330 (manufactured by Ciba Specialty Chemicals), and 0.6 parts by mass of tetrabutyl titanate were charged, and the temperature was raised from room temperature to 210°C over 2 hours, and then heated at 210°C for 1 hour to carry out a transesterification reaction. The pressure inside the vessel was then gradually reduced and the temperature was raised, and the pressure was lowered to 245°C and 130 Pa or less over 50 minutes to carry out an initial polymerization reaction. Further polymerization was carried out for 2.5 hours at 245°C and 130 Pa or less, and the resulting molten polyester resin was withdrawn in the form of strands from the outlet at the bottom of the polymerization vessel, cooled in a water bath, and then cut into chips to obtain Polyester Elastomer A-2. The hard segment content was 68% by mass, and the reduced viscosity was 1.6 dl / g.

[0114] (Polyester Elastomer A-3) 1,080 parts by mass of dimethyl terephthalate, 769 parts by mass of 1,4-butanediol, 211 parts by mass of polytetramethylene glycol (number average molecular weight 1,000), 1.4 parts by mass of Irganox 1330 (manufactured by Ciba Specialty Chemicals), and 0.6 parts by mass of tetrabutyl titanate were charged, and the temperature was raised from room temperature to 210°C over 2 hours, and then heated at 210°C for 1 hour to carry out a transesterification reaction. The pressure inside the vessel was then gradually reduced and the temperature was raised, and the pressure was lowered to 245°C and 130 Pa or less over 50 minutes to carry out an initial polymerization reaction. Further polymerization was carried out for 2.5 hours at 245°C and 130 Pa or less, and the resulting molten polyester resin was withdrawn in the form of strands from the outlet at the bottom of the polymerization vessel, cooled in a water bath, and then cut into chips to obtain Polyester Elastomer A-3. The hard segment content was 83% by mass, and the reduced viscosity was 1.3 dl / g.

[0115] (Polyester Elastomer A-4) 810 parts by mass of dimethyl terephthalate, 485 parts by mass of 1,4-butanediol, 790 parts by mass of polytetramethylene glycol (number average molecular weight 1000), 1.4 parts by mass of Irganox 1330 (manufactured by Ciba Specialty Chemicals), and 0.6 parts by mass of tetrabutyl titanate were charged, and the temperature was raised from room temperature to 210°C over 2 hours, and then heated at 210°C for 1 hour to carry out a transesterification reaction. The pressure inside the vessel was then gradually reduced and the temperature was raised, and the pressure was lowered to 245°C and 130 Pa or less over 50 minutes to carry out an initial polymerization reaction. The polymerization reaction was further carried out for 2.5 hours at 245°C and 130 Pa or less, and the resulting molten polyester resin was withdrawn in the form of strands from the outlet at the bottom of the polymerization vessel, cooled in a water bath, and then cut into chips to obtain Polyester Elastomer A-4. The hard segment content was 45% by mass, and the reduced viscosity was 2.0 dl / g.

[0116] (Polyester Elastomer A-5) Polyester Elastomer A-2 was treated (solid-state polymerization) in a vacuum at 190°C for 20 hours. The resulting polyester elastomer A-5 had a hard segment content of 68% by mass, a reduced viscosity of 3.3 dl / g, and a number average molecular weight Mn of 45,000.

[0117] (Polyester Elastomer A-6) 845 parts by mass of dimethyl terephthalate, 4.8 parts by mass of trimellitic anhydride, 660 parts by mass of 1,4-butanediol, 425 parts by mass of polytetramethylene glycol (number average molecular weight 1000), 1.4 parts by mass of Irganox 1330 (manufactured by Ciba Specialty Chemicals), and 0.6 parts by mass of tetrabutyl titanate were charged, and the temperature was raised from room temperature to 210°C over 2 hours, and then heated at 210°C for 1 hour to carry out a transesterification reaction. The pressure inside the vessel was then gradually reduced and the temperature was raised, and the pressure was lowered to 245°C and 130 Pa or less over 50 minutes to carry out an initial polymerization reaction. The polymerization reaction was further carried out for 2.5 hours at 245°C and 130 Pa or less, and the resulting molten polyester resin was withdrawn in the form of strands from the outlet at the bottom of the polymerization vessel, cooled in a water bath, and then cut into chips to obtain Polyester Elastomer A-6. The hard segment content was 68% by mass, and the reduced viscosity was 2.2 dl / g.

[0118] The reduced viscosity (dl / g) of the polyester elastomer was measured at 30° C. using an Ubbelohde viscometer after dissolving 0.05 g of the polyester elastomer in 25 mL of a mixed solvent (phenol / tetrachloroethane=60 / 40).

[0119] <Thickener B> (Thickener B-1) Styrene / glycidyl acrylate copolymer (ARUFON UG-4050, manufactured by Toagosei Co., Ltd., Mw: 8500, epoxy value: 670 equivalents / 1×10 6 g, average number of epoxy groups per molecule: 3 or more) (Thickener B-2) Polyethylene glycol diglycidyl ether ("Denacol EX-850", manufactured by Nagase ChemteX Corporation, epoxy valence (average number of epoxy groups per molecule): 2) (Thickener B-3) Polycarbodiimide ("Carbodilite HMV-8CA", manufactured by Nisshinbo Chemical Inc., carbodiimide valence (average number of carbodiimide groups per molecule): 11)

[0120] <Other additives> (Stabilizer) Hindered phenol-based antioxidant ("Irganox 1010", manufactured by BASF) (Mold release agent) Mold release agent ("Licorb WE40", manufactured by Clariant Japan Co., Ltd.) (Nucleating agent) Sodium stearate (manufactured by NOF Corporation)

[0121] Examples 1 to 6 and Comparative Examples 1 to 6 According to the formulations shown in Table 1, various components were melt-kneaded with 100 parts by mass of thermoplastic polyester elastomer (A) using a twin-screw extruder, and then pelletized to obtain pellets of the polyester elastomer resin compositions of Examples 1 to 6 and Comparative Examples 1 to 6.

[0122] Next, a foam-molded article was produced using the polyester elastomer resin composition obtained above by the mold expansion method described above. A flat plate-making mold was used, consisting of a fixed mold and a moving mold. When clamped, a cavity measuring 100 mm in width, 100 mm in length, and 3 mm in thickness was formed. When core-backed in the mold opening direction, a cavity of the same width and length but with a thickness of 3 mm plus the core-back amount (mm) was formed. Specifically, in the plasticization zone of an electric injection molding machine with a clamping force of 1800 kN, a screw diameter of 40 mm, and a screw stroke of 180 mm, 0.5 parts by mass of supercritical nitrogen was injected per 100 parts by mass of the polyester elastomer resin composition. The mixture was injected into a mold whose surface temperature was controlled to 50°C. The moving mold was then moved in the mold opening direction (core-back amount: 13.0 mm) to expand the cavity volume and obtain a foam-molded article.

[0123] The polyester elastomer resin compositions for foam molding obtained in Examples 1 to 6 and Comparative Examples 1 to 6 and the foam molded articles obtained from the resin compositions were evaluated as follows. The results are shown in Table 1.

[0124] [Temperature-decreasing crystallization temperature (TC2), melting point (Tm)] Measured in accordance with ASTM D-3418. Specifically, using a differential scanning calorimeter "DSC220" manufactured by Seiko Instruments Inc., 5 mg of a measurement sample was placed in an aluminum pan, the lid was pressed down and sealed, and the temperature was increased to 250°C at a heating rate of 20°C / min under a nitrogen gas flow. The endothermic peak temperature due to melting from the obtained thermogram curve was taken as the melting point (Tm). Furthermore, after melting at 250°C for 2 minutes, the temperature was decreased to 50°C at a cooling rate of 20°C / min. The exothermic peak temperature due to crystallization from the obtained thermogram curve was taken as the temperature-decreasing crystallization temperature (TC2).

[0125] [Density (Apparent Density)] The dimensions of the foamed molded article were measured with a vernier caliper to calculate the volume, and the mass was measured with an electronic balance, and the density was calculated according to the following formula: Density (g / cm 3 ) = mass of foamed molded article / volume of foamed molded article

[0126] [Melt Viscosity η10, η15] The melt viscosity of the prepared polyester elastomer resin composition was measured using a "Capillograph 1D" manufactured by Toyo Seiki Seisakusho, Ltd. Specifically, the value measured under the conditions of capillary diameter: 1.0 mm, capillary length: 40 mm, cylinder diameter: 9.55 mm, shear rate: 10 / sec, and temperature: Tm (melting point of polyester elastomer resin composition) + 10°C was defined as η10. As above, the value measured under the condition of temperature: Tm + 15°C was defined as η15.

[0127] [Temperature Dependence of Melt Viscosity] The value calculated by the following formula was used as an index of the temperature dependency of melt viscosity: (Temperature Dependence)=(η10-η15) / η15

[0128] [Foam Cell Uniformity] Foam molding was performed continuously, and the sample from the fifth shot was evaluated using the following method. A photograph of the foam cross section of the sample for cross-section observation, taken with a scanning electron microscope SU1510 manufactured by Hitachi High-Technologies Corporation, was image-processed, and the circle-equivalent diameter of each of 100 adjacent cells was taken as the cell diameter, which was measured with a vernier caliper. The average value (p) of these 100 cells was calculated, and this was performed at three arbitrary locations. The average of the three average values ​​(p) obtained at the three locations was taken as the average cell diameter P. The average value (q) of the top 20 cell diameters of the 100 cells was also calculated, and the average of the three average values ​​(q) obtained at the three locations was taken as the average cell diameter Q of the top 20 cells. (Foam Cell Uniformity) = (Average Cell Diameter Q of Top 20 Cells) / (Average Cell Diameter P) Foam cell uniformity was evaluated using the following index. The above calculation was rounded to one decimal place. 1.4 or less: 0 1.5 to 1.7: △ 1.8 or more: X

[0129] [Dv / Dn of Foam Cells] Foam molding was continuously performed, and the sample obtained after the fifth shot was evaluated by the following method. Images of the foam cross section of a sample for cross-section observation, taken with a scanning electron microscope SU1510 manufactured by Hitachi High-Technologies Corporation, were processed within an area of ​​6000 μm × 5000 μm. The equivalent circle diameters of 100 adjacent foam cells (when foam cells were observed to be elliptical, the average of the major and minor diameters was used as the equivalent circle diameter) were measured with calipers as the foam cell diameter. This was performed at the following three locations. From the diameters of a total of 300 foam cells obtained at the three locations, the volume average cell diameter Dv and the number average cell diameter Dn were calculated based on the formula described below, and Dv / Dn was calculated. Table 1 shows the measurement results of the number average cell diameter Dn and Dv / Dn. First location: Starting from the largest foam cell within the image-processed area, 100 adjacent foam cells were extracted in descending order. Second location: Starting from the smallest foam cell in the area where image processing was performed, 100 adjacent foam cells were extracted in order from the smallest. Third location: Starting from any foam cell in the area where image processing was performed, 100 adjacent foam cells were extracted in order from the largest. Number average cell diameter Dn = Σd i / n Volume average cell diameter Dv = Σ (V i ・d i ) / Σ(V i ) (where d i is the diameter of each foam cell, n is the total number of foam cells measured (300 cells), and V i is d i (This is the volume of each foam cell calculated by assuming that each foam cell is a perfect sphere.)

[0130] [Stability of foam cell uniformity over time] Foam molding was carried out continuously, and the sample from the 60th shot was evaluated in the same manner as in [Foam cell uniformity]. If the evaluation of the sample from the 5th shot was good and the evaluation of the sample from the 60th shot was similar, it could be determined that the stability over time was good.

[0131] [Δ(Dv / Dn)] Foam molding was carried out continuously, and the sample obtained after the 60th shot was evaluated in the same manner as in [Dv / Dn of foam cells] above. The Dv / Dn of the foam molded product obtained after the 5th shot was (Dv / Dn)5, and the Dv / Dn of the foam molded product obtained after the 60th shot was (Dv / Dn) 60 Then, Δ(Dv / Dn) was calculated based on the following formula: Δ(Dv / Dn)=(Dv / Dn) 60 -(Dv / Dn)5

[0132] [Mn, Mw] 2 mg of the resin component was weighed and dissolved in 4 ml of 10 mM HFIP / sodium trifluoroacetate. The solution was filtered through a 2 μm membrane filter, and the resulting sample solution was subjected to GPC analysis under the following conditions. The number average molecular weight (Mn) and weight average molecular weight (Mw) were calculated in terms of polymethyl methacrylate (PMMA). Apparatus: TOSOH HLC-8320GPC Column: TOSOH TSKgel Super HM-H x 2 + TSKgel Super H2000 Solvent: 10 mM HFIP / sodium trifluoroacetate Flow rate: 0.2 ml / min Injection volume: 10 μl Temperature: 40°C Detector: RI Concentration: 0.05%

[0133] [Appearance of molded article] The appearance of the foamed molded article obtained above was evaluated according to the following criteria. ◯: No gel-like matter or irregularities, and good surface smoothness. Δ: Corresponding to any of the following: gel-like matter was slightly observed, slight ejector pin marks, or slight surface roughness, and none of the requirements listed below as × were met. ×: Corresponding to any of the following: gel-like matter was significantly observed, clear irregularities were present, or the surface was very rough.

[0134] [Deflection Temperature Under Load] Measurement was carried out in accordance with ISO 75 (0.45 MPa) using a test piece having a length of 80 mm, a width of 10 mm and a thickness of 4 mm obtained by short-shot injection molding so that the expansion ratio was 1.5 times.

[0135]

[0136] As is clear from Table 1, Examples 1 to 6, which fall within the scope of the present invention, produced foamed molded articles with uniform foam cells, especially even after long molding times. On the other hand, Comparative Examples 1, 2, and 5, which had low melt viscosities, showed many broken cells and poor foamability. Furthermore, gel-like materials were observed in the molded article of Comparative Example 5. Comparative Example 3, which did not satisfy formula (iii), showed changes in foam cell size with increasing molding time, failing to produce foamed molded articles of consistent quality. Comparative Example 4, which did not satisfy formula (i), failed to produce a high-expansion foam due to the resin composition solidifying too quickly, and the foam cell diameter was not uniform, resulting in roughness on the molded article surface. Furthermore, Comparative Example 6, which used a polyester elastomer with a low hard segment ratio, exhibited a low deflection temperature under load, poor heat resistance, and clear ejector pin marks remained on the surface.

[0137] The polyester elastomer resin composition of the present invention and a foam molded article made thereof have stable foaming properties and are extremely useful because they can be used to stably produce foams that are lightweight, have high impact absorption properties, and are excellent in heat resistance and mechanical properties.

Claims

1. A polyester elastomer resin composition for foam molding, comprising as a main component a thermoplastic polyester elastomer (A) having a hard segment made of a polyester containing an aromatic dicarboxylic acid and an aliphatic and / or alicyclic diol as constituent components, and at least one soft segment selected from aliphatic polyethers, aliphatic polyesters, and aliphatic polycarbonates, the hard segment content of which is 50 to 95 mass%, and characterized in that the composition satisfies the following (i) to (iii): (i) 10°C≦Tm−TC2≦65°C (where Tm is the melting point of the polyester elastomer resin composition, and TC2 is the crystallization temperature on cooling of the polyester elastomer resin composition); (ii) η10≧1×10 3 Pa s (iii) (η10 - η15) / η15 ≦ 1 (where η10 is the melt viscosity of the polyester elastomer resin composition measured at [melting point + 10°C], η15 is the melt viscosity of the polyester elastomer resin composition measured at [melting point + 15°C], and the melt viscosity measurement conditions are capillary diameter: 1.0 mm, capillary length: 40 mm, cylinder diameter: 9.55 mm, and shear rate: 10 / sec.) 2. The polyester elastomer resin composition for foam molding according to claim 1, which satisfies the following (iv): (iv) Mw / Mn≧2.5 (where Mn and Mw are the number average molecular weight and weight average molecular weight of the polyester elastomer resin composition, respectively).

3. The polyester elastomer resin composition for foam molding according to claim 1, characterized in that Mn≧35,000 and Mw / Mn≧3.5 (Mn and Mw are the number average molecular weight and weight average molecular weight of the polyester elastomer resin composition, respectively).

4. A polyester elastomer resin composition for foam molding according to claim 1, characterized in that the polyester elastomer resin composition contains a thickener (B), and the thickener (B) has at least one functional group (b) capable of reacting with the terminal group of the thermoplastic polyester elastomer (A).

5. The polyester elastomer resin composition for foam molding according to claim 1, characterized in that the polyester elastomer resin composition does not contain a thickener (B) or contains it in an amount of 4.5 parts by mass or less per 100 parts by mass of the thermoplastic polyester elastomer (A), and the thickener (B) has at least one functional group (b) capable of reacting with an end group of the thermoplastic polyester elastomer (A).

6. The polyester elastomer resin composition for foam molding according to claim 4, characterized in that the functional group (b) is at least one selected from the group consisting of an epoxy group, an acid anhydride group, a carbodiimide group and an isocyanate group.

7. A polyester elastomer resin composition for foam molding as described in claim 4, characterized in that the polyester elastomer resin composition contains, as the thickener (B), a thickener (B1) having three or more functional groups (b) in one molecule, and the content of the thickener (B1) is 1 part by mass or less per 100 parts by mass of the thermoplastic polyester elastomer (A).

8. A polyester elastomer resin composition for foam molding as described in claim 4, characterized in that the polyester elastomer resin composition contains, as the thickener (B), a thickener (B1) having three or more functional groups (b) in one molecule and a thickener (B2) having two functional groups (b) in one molecule, and the content of thickener (B1) is 1 part by mass or less per 100 parts by mass of thermoplastic polyester elastomer (A).

9. The polyester elastomer resin composition for foam molding according to claim 1, wherein the polyester elastomer resin composition does not contain a thickener (B), and the number average molecular weight (Mn) of the thermoplastic polyester elastomer (A) is 35,000 or more.

10. The polyester elastomer resin composition for foam molding according to claim 1, wherein the thermoplastic polyester elastomer (A) has a branched structure.

11. The polyester elastomer resin composition for foam molding according to claim 1, wherein the content of hard segments in the thermoplastic polyester elastomer (A) is 55% by mass or more, and the amount of isophthalic acid components in all acid components constituting the polyester of the hard segments is 10 mol% or less.

12. The polyester elastomer resin composition for foam molding according to claim 1, wherein the polyester elastomer resin composition does not contain a nucleating agent or contains a nucleating agent in an amount of less than 0.1 parts by mass per 100 parts by mass of the thermoplastic polyester elastomer (A).

13. The polyester elastomer resin composition according to claim 1, which is suitable for injection foam molding, extrusion foam molding, or batch foam molding.

14. A foam-molded article made from the polyester elastomer resin composition for foam molding according to any one of claims 1 to 13.

15. The foamed molded article according to claim 14, wherein the ratio (Dv / Dn) of the volume average cell diameter Dv to the number average cell diameter Dn of the foamed cells of the foamed molded article is 4 or less.

16. Use of the polyester elastomer resin composition according to any one of claims 1 to 13 in foam molding.

17. A method for producing a foamed molded article, comprising the step of foam-molding the polyester elastomer resin composition according to any one of claims 1 to 13.

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