Polyester elastomer resin composition

Abstract

To provide a polyester elastomer resin composition which is excellent in a silencing characteristic by suppressing a surface hardness, has sufficient flexural modulus as a member, and a small mold shrinkage factor, and is excellent in strand stability.SOLUTION: A thermoplastic elastomer resin composition contains: a polyester block copolymer (A) having as the main constituents, a high-melting-point crystalline polymer segment (a) comprising a crystalline aromatic polyester unit, and a low-melting-point polymer segment (b) comprising an aliphatic polyether unit; a rubbery graft copolymer (B) obtained by copolymerizing a vinyl monomer containing an aromatic vinyl monomer and a vinyl cyanide monomer as the main constituents in the presence of a rubbery polymer; and a vinyl-based copolymer (C) obtained by copolymerizing a vinyl monomer containing an aromatic vinyl monomer and a vinyl cyanide monomer as the main constituents. The resin composition contains 50-79 mass% of the polyester block copolymer (A), 1-15 mass% of the rubbery graft copolymer (B), and 20-35 mass% of the vinyl-based copolymer (C) based on the total amount 100 mass% of the polyester block copolymer (A), the rubbery graft copolymer (B) and the vinyl-based copolymer (C).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a polyester elastomer resin composition. [Background technology]

[0002] Polyester block copolymers, which have crystalline aromatic polyester units as hard segments and aliphatic polyether units such as poly(alkylene oxide) glycol as soft segments, are widely used in fields such as automobiles, electrical and electronic parts, and consumer goods because they have excellent mechanical properties such as strength, impact resistance, elastic recovery, and flexibility, as well as low- and high-temperature properties, and are thermoplastic and easy to mold.

[0003] In general, the higher the proportion of low-melting-point polymer segments in the above-mentioned polyester block copolymers, the higher the flexibility and the better the sound-deadening properties. It is known that they have particularly excellent sound-deadening properties against impact noise, and surface hardness contributes to this. On the other hand, their mechanical properties tend to improve as the proportion of high-melting-point crystalline polymer segments increases. Due to this property, polyester block copolymers with high hardness are often used in applications requiring high component strength, resulting in insufficient sound-deadening properties. Therefore, flexible polyester block copolymers with high sound-deadening properties are currently limited to applications where component strength requirements are low.

[0004] However, in recent years, there has been an increasing demand for higher performance resin materials in various fields. For example, in the automotive field, there is a demand for automotive parts that combine sound-deadening properties with component strength in order to reduce interior noise and create a comfortable interior space.

[0005] As a conventional technique for improving the strength of a flexible polyester block copolymer with high sound-absorbing properties, a thermoplastic polyester resin composition containing a hard polyester resin (polybutylene terephthalate resin, polybutylene naphthalate resin) has been proposed (see, for example, Patent Document 1), and a thermoplastic polyester resin composition containing a low-hardness polyester block copolymer and a high-hardness polyester block copolymer has also been proposed (see, for example, Patent Document 2).

[0006] Furthermore, polyester block copolymers have a problem of high molding shrinkage. This is because, due to the presence of crystalline aromatic polyester units, when a molten polyester is filled into a mold and solidified, a crystalline structure is formed in which the molecules are regularly arranged, resulting in a large volume loss. In particular, in molded articles with complex shapes, the difference in shrinkage due to the volume loss between thick and thin parts becomes large, making it difficult to obtain molded articles with the desired shape.

[0007] As prior art for reducing the molding shrinkage rate of polyester block copolymers, a thermoplastic polyester resin composition in which acrylonitrile-butadiene-styrene resin (ABS resin) and acrylonitrile-styrene resin (AS resin) are blended in a specific ratio (see, for example, Patent Document 3) has been proposed, and a thermoplastic polyester resin composition in which ABS resin and polycarbonate resin (PC resin) are blended in a specific ratio (see, for example, Patent Document 4) has also been proposed. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-133810 [Patent Document 2] Japanese Patent Application Laid-Open No. 2011-116856 [Patent Document 3] Japanese Patent Publication No. 2024-022528 [Patent Document 4] Japanese Patent Application Laid-Open No. 2008-189715 Summary of the Invention [Problem to be solved by the invention]

[0009] However, while the above-mentioned conventional proposals are effective in improving the elastic modulus and reducing the molding shrinkage rate, they are unable to maintain a low surface hardness, which is an important characteristic of polyester block copolymers, and the sound-deadening properties are insufficient.

[0010] The present invention aims to solve the problems in the prior art described above as well as problems discovered by the inventors, and aims to provide a polyester elastomer resin composition that has excellent sound-deadening properties by suppressing surface hardness, has sufficient strength as a component, has a small molding shrinkage rate, and is excellent in strand stability. [Means for solving the problem]

[0011] As a result of extensive research into achieving the above object, the present inventors have discovered that the above object can be effectively achieved by blending specific amounts of a specific rubber graft copolymer and a specific vinyl copolymer with a polyester block copolymer, and have arrived at the present invention.

[0012] That is, the aspects of the present invention are as follows. (1) A thermoplastic elastomer resin composition comprising: a polyester block copolymer (A) having as its main components a high-melting-point crystalline polymer segment (a) composed of crystalline aromatic polyester units; and a low-melting-point polymer segment (b) composed of aliphatic polyether units; a rubbery graft copolymer (B) obtained by copolymerizing a monomer component containing, as main components, an aromatic vinyl monomer and a vinyl cyanide monomer in the presence of a rubbery polymer; and a vinyl copolymer (C) composed of an aromatic vinyl monomer and a vinyl cyanide monomer, wherein the thermoplastic elastomer resin composition contains 50 to 79 mass% of the polyester block copolymer (A), 1 to 15 mass% of the rubbery graft copolymer (B), and 20 to 35 mass% of the vinyl copolymer (C) relative to 100 mass% of the total of the polyester block copolymer (A), the rubbery graft copolymer (B), and the vinyl copolymer (C). (2) The thermoplastic elastomer resin composition according to (1), wherein the flexural modulus (M) (unit: MPa) measured according to ASTM D790 and the surface hardness (H) (unit: D) ​​measured according to JIS K7215:1986 using a durometer D satisfy the relationship of formula (i). (M)>18×(H)-665 ···(i) (3) The thermoplastic elastomer resin composition according to (1) or (2), which has a flexural modulus (M) of 235 MPa or more when measured according to ASTM D790. (4) The thermoplastic elastomer resin composition according to any one of (1) to (3), characterized in that the mass ratio of the high-melting point crystalline polymer segment (a) to the low-melting point polymer segment (b) in the polyester block copolymer (A) is 55 / 45 to 20 / 80. (5) The thermoplastic elastomer resin composition according to any one of (1) to (4), characterized in that it contains 0.05 to 1.0 parts by mass of an inorganic material (D) per 100 parts by mass of the thermoplastic elastomer resin composition. (6) The thermoplastic elastomer resin composition according to any one of (1) to (5), characterized in that it contains 0.05 to 3.0 parts by mass of a sliding agent (E) per 100 parts by mass of the thermoplastic elastomer resin composition. (7) The thermoplastic elastomer resin composition according to any one of (1) to (6), characterized in that the rubbery graft copolymer (B) is obtained by graft polymerizing 40 to 85 parts by mass of a diene-based rubbery polymer and 15 to 60 parts by mass of a vinyl monomer containing an aromatic vinyl monomer and a vinyl cyanide monomer as main components, so that the total amount is 100 parts by mass, and the graft ratio of the vinyl monomer component is 25% or more. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide a polyester elastomer resin composition which has excellent sound-deadening properties by suppressing the surface hardness, has a sufficient flexural modulus for use as a component, has a small molding shrinkage rate, and has excellent strand stability. DETAILED DESCRIPTION OF THE INVENTION

[0014] The present invention will be described in detail below.

[0015] The thermoplastic elastomer resin composition of the present invention comprises a polyester block copolymer (A) (hereinafter sometimes referred to as polyester block copolymer (A)) whose main components are a high-melting point crystalline polymer segment (a) composed of crystalline aromatic polyester units and a low-melting point polymer segment (b) composed of aliphatic polyether units; a rubbery graft copolymer (B) (hereinafter sometimes referred to as rubbery graft copolymer (B)) obtained by copolymerizing a vinyl monomer containing, as main components, an aromatic vinyl monomer and a vinyl cyanide monomer in the presence of a rubbery polymer; and a vinyl-based copolymer (C) (hereinafter sometimes referred to as vinyl-based copolymer (C)) obtained by copolymerizing a vinyl monomer containing, as main components, an aromatic vinyl monomer and a vinyl cyanide monomer, wherein the thermoplastic elastomer resin composition contains 50 to 79 mass% of the polyester block copolymer (A), 1 to 15 mass% of the rubbery graft copolymer (B), and 20 to 35 mass% of the vinyl-based copolymer (C) relative to 100 mass% combined of the polyester block copolymer (A), the rubbery graft copolymer (B), and the vinyl-based copolymer (C).

[0016] The polyester block copolymer (A) used in the present invention is mainly composed of a high-melting crystalline polymer segment (a) mainly composed of crystalline aromatic polyester units and a low-melting polymer segment (b) mainly composed of aliphatic polyether units. The high-melting crystalline polymer segment (a) is a polyester formed mainly from an aromatic dicarboxylic acid or its ester-forming derivative and a diol or its ester-forming derivative. Specific examples of aromatic dicarboxylic acids include terephthalic acid, isophthalic acid, phthalic acid, naphthalene-2,6-dicarboxylic acid, naphthalene-2,7-dicarboxylic acid, anthracene dicarboxylic acid, diphenyl-4,4'-dicarboxylic acid, diphenoxyethane dicarboxylic acid, 4,4'-diphenyl ether dicarboxylic acid, 5-sulfoisophthalic acid, and sodium 3-sulfoisophthalate. Although aromatic dicarboxylic acids are primarily used, if necessary, a portion of the aromatic dicarboxylic acids may be substituted with alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid, cyclopentanedicarboxylic acid, 4,4'-dicyclohexyldicarboxylic acid, etc., or aliphatic dicarboxylic acids such as adipic acid, succinic acid, oxalic acid, sebacic acid, dodecanedioic acid, dimer acid, etc. Ester-forming derivatives of dicarboxylic acids, such as lower alkyl esters, aryl esters, carbonate esters, and acid halides, may also be used.

[0017] Specific examples of the diol include diols having a molecular weight of 400 or less, such as aliphatic diols such as 1,4-butanediol, ethylene glycol, trimethylene glycol, pentamethylene glycol, hexamethylene glycol, neopentyl glycol, and decamethylene glycol; alicyclic diols such as 1,1-cyclohexanedimethanol, 1,4-dicyclohexanedimethanol, and tricyclodecane dimethanol; and aromatic diols such as xylylene glycol, bis(p-hydroxy)diphenyl, bis(p-hydroxy)diphenylpropane, 2,2′-bis[4-(2-hydroxyethoxy)phenyl]propane, bis[4-(2-hydroxyethoxy)phenyl]sulfone, 1,1-bis[4-(2-hydroxyethoxy)phenyl]cyclohexane, 4,4′-dihydroxy-p-terphenyl, and 4,4′-dihydroxy-p-quarterphenyl. These diols may also be used in the form of ester-forming derivatives, such as acetylated forms and alkali metal salts.

[0018] Two or more of these dicarboxylic acids, derivatives thereof, diol components, and derivatives thereof may be used in combination. A preferred example of the high-melting-point crystalline polymer segment (a) is a polybutylene terephthalate unit derived from terephthalic acid and / or dimethyl terephthalate and 1,4-butanediol. Also preferred is a polymer segment consisting of a polybutylene terephthalate unit derived from terephthalic acid and / or dimethyl terephthalate and a polybutylene isophthalate unit derived from isophthalic acid and / or dimethyl isophthalate and 1,4-butanediol.

[0019] The low-melting-point polymer segment (b) of the polyester block copolymer (A) used in the present invention is an aliphatic polyether. Specific examples of this aliphatic polyether include poly(ethylene oxide) glycol, poly(propylene oxide) glycol, poly(trimethylene ether) glycol, poly(tetramethylene oxide) glycol, poly(hexamethylene oxide) glycol, copolymers of ethylene oxide and propylene oxide, ethylene oxide adducts of poly(propylene oxide) glycol, and copolymers of ethylene oxide and tetrahydrofuran. Among these, poly(tetramethylene oxide) glycol and / or ethylene oxide adducts of poly(propylene oxide) glycol and / or copolymers of ethylene oxide and tetrahydrofuran are preferred. Furthermore, the number-average molecular weight of these low-melting-point polymer segments (b) in the copolymerized state is preferably about 300 to 6,000.

[0020] The mass ratio of the high melting point crystalline polymer segment (a) to the low melting point polymer segment (b) in the polyether ester block copolymer (A) used in the present invention is preferably 55 / 45 to 20 / 80, more preferably 50 / 50 to 25 / 75 mass%.

[0021] The polyester block copolymer (A) used in the present invention can be produced by a known method, such as a method of transesterifying a lower alcohol diester of a dicarboxylic acid, an excess amount of a low-molecular-weight glycol, and a low-melting-point polymer segment component in the presence of a catalyst, followed by polycondensation of the resulting reaction product, or a method of esterifying a dicarboxylic acid, an excess amount of a glycol, and a low-melting-point polymer segment component in the presence of a catalyst, followed by polycondensation of the resulting reaction product.

[0022] The rubbery graft copolymer (B) used in the present invention is a graft polymer obtained by graft polymerizing a vinyl monomer containing an aromatic vinyl monomer and a vinyl cyanide monomer as main components in the presence of a rubbery polymer.

[0023] Examples of rubbery polymers include diene polymers such as polybutadiene, styrene-butadiene copolymer, and acrylonitrile-butadiene copolymer, ethylene-propylene copolymers such as ethylene-propylene copolymer and ethylene-propylene-non-conjugated diene copolymer, acrylic ester copolymer, and chlorinated polyethylene, and one or more of these can be used. Among these, diene polymers are preferably used because of their good moldability and dispersibility with polyester block copolymers.

[0024] Examples of aromatic vinyl monomers include styrene, α-methylstyrene, p-methylstyrene, pt-butylstyrene, etc. Among these, styrene and / or α-methylstyrene are preferably used.

[0025] Examples of vinyl cyanide monomers include acrylonitrile and methacrylonitrile, with acrylonitrile being preferred.

[0026] Other vinyl monomers may be copolymerized within the range that does not impair the effects of the present invention. Examples of copolymerizable other vinyl monomers include α,β-unsaturated carboxylic acids such as acrylic acid and methacrylic acid, α,β-unsaturated carboxylic acid esters such as methyl methacrylate, ethyl methacrylate, t-butyl methacrylate, and cyclohexyl methacrylate, α,β-unsaturated dicarboxylic acid anhydrides such as maleic anhydride and itaconic anhydride, and imide compounds of α,β-unsaturated dicarboxylic acids such as N-phenylmaleimide, N-methylmaleimide, and N-t-butylmaleimide.

[0027] The rubbery graft polymer (B) used in the present invention is preferably obtained by graft polymerizing 40 to 85 parts by mass of a diene rubbery polymer with 15 to 60 parts by mass of a vinyl monomer containing an aromatic vinyl monomer and a vinyl cyanide monomer as main components, so that the total amount is 100 parts by mass. If the vinyl monomer component is less than 15 parts by mass, the graft ratio will be relatively low, making it difficult to obtain good mechanical properties. Furthermore, if the diene rubbery polymer is less than 40 parts by mass or more than 85 parts by mass, compatibility with the polyester block copolymer will tend to decrease.

[0028] The proportion of aromatic vinyl monomer to be graft-polymerized is preferably 50 to 99% by mass, more preferably 60 to 90% by mass, and even more preferably 70 to 80% by mass, based on the total vinyl monomer content. The proportion of vinyl cyanide monomer is preferably 1 to 50% by mass, more preferably 10 to 40% by mass, and even more preferably 20 to 30% by mass. If the proportion of aromatic vinyl monomer exceeds 99% by mass or is less than 50% by mass, or if the proportion of vinyl cyanide monomer exceeds 50% by mass or is less than 1% by mass, compatibility with the polyester block copolymer decreases, and good mechanical properties may not be obtained. Furthermore, it is preferable to use other vinyl monomers copolymerizable with these monomers in an amount of 50% by mass or less.

[0029] The graft ratio of vinyl monomer to diene rubbery polymer in the rubbery graft copolymer (B) used in the present invention is preferably 25% or more, more preferably 30% or more, and even more preferably 35% or more. If the graft ratio is less than 25%, the rubbery polymers will aggregate during melt-kneading, which will impair the mechanical properties of the resulting thermoplastic elastomer resin composition, which is not preferred.

[0030] The rubbery graft copolymer (B) of the present invention can be produced by any known method, such as emulsion graft polymerization. The emulsifier, polymerization initiator, and chain transfer agent used herein can be any of the reagents commonly used in emulsion polymerization. Typical emulsifiers include potassium rosinate, potassium stearate, and potassium oleate. Typical polymerization initiators include a combination of organic hydroperoxides and sugar-containing pyrophosphate-ferrous sulfate, and persulfates. Typical chain transfer agents include alkylthiol compounds, although the present invention is not limited to these.

[0031] The vinyl copolymer (C) used in the present invention is a copolymer obtained by copolymerizing an aromatic vinyl monomer and a vinyl monomer containing a vinyl cyanide monomer as the main component.

[0032] Examples of aromatic vinyl monomers include styrene, α-methylstyrene, p-methylstyrene, pt-butylstyrene, etc. Among these, styrene and / or α-methylstyrene are preferably used.

[0033] Examples of vinyl cyanide monomers include acrylonitrile and methacrylonitrile, with acrylonitrile being preferred.

[0034] Furthermore, other vinyl monomers may be copolymerized within the range that does not impair the effects of the present invention. Examples of other copolymerizable vinyl monomers are as described above.

[0035] The vinyl copolymer (C) used in the present invention is preferably an acrylonitrile-styrene copolymer.

[0036] The thermoplastic elastomer resin composition of the present invention is a thermoplastic elastomer resin composition obtained by blending 50 to 79 mass% of the polyester block copolymer (A), 1 to 15 mass% of the rubbery graft copolymer (B), and 20 to 35 mass% of the vinyl copolymer (C) relative to a total of 100 mass% of the above-mentioned polyester block copolymer (A), rubbery graft copolymer (B), and vinyl copolymer (C). The resin composition is preferably a resin composition obtained by blending 60 to 77 mass% of the polyester block copolymer (A), 3 to 10 mass% of the rubbery graft copolymer (B), and 20 to 30 mass% of the vinyl copolymer (C). The resin composition is more preferably a resin composition obtained by blending 60 to 70 mass% of the polyester block copolymer (A), 5 to 10 mass% of the rubbery graft copolymer (B), and 25 to 30 mass% of the vinyl copolymer (C).

[0037] If the content of the polyester block copolymer (A) is less than 50% by mass, the flexibility and moldability of the polyester elastomer are impaired, which is undesirable. If it exceeds 79% by mass, formula (i) is not satisfied, which is undesirable. 60% by mass or more is preferable. If the content of the rubbery graft copolymer (B) is less than 1% by mass, the strand stability of the resin composition during melt-kneading is poor, making it impossible to form uniformly shaped pellets. If it exceeds 15% by mass, the flexibility of the polyester elastomer is impaired, which is undesirable. If the content of the vinyl copolymer (C) is less than 20% by mass, formula (i) is not satisfied, and if it exceeds 35% by mass, the flexibility of the polyester elastomer is impaired and the strand stability of the resin composition during melt-kneading is poor, making it impossible to form uniformly shaped pellets. 30% by mass or less is preferable. By blending specific amounts of a rubbery graft copolymer (B) and a vinyl copolymer (C) in combination with a polyester block copolymer (A), it is possible to obtain a polyester elastomer resin composition that has low surface hardness, excellent sound-deadening properties, sufficient strength for components, low molding shrinkage, and excellent strand stability.

[0038] There are no limitations on the method for mixing the polyester block copolymer (A), rubbery graft copolymer (B), and vinyl copolymer (C) of the present invention, and examples thereof include a method of mixing (A), (B), and (C) all at once, or a method of melting any of them and then mixing the remaining components.Known methods such as a Banbury mixer or an extruder can be used as the kneading method.

[0039] The thermoplastic elastomer resin composition of the present invention preferably contains an inorganic material (D). The inorganic material (D) used in the present invention is a plate-like filler. Specific examples of the plate-like filler include talc, mica, and glass flakes.

[0040] The content of the inorganic material (D) is preferably 0.05 to 1.0 part by mass, more preferably 0.05 to 0.8 part by mass, and even more preferably 0.1 to 0.5 part by mass, relative to 100 parts by mass of the thermoplastic elastomer resin composition. When the content of the inorganic material (D) is 0.05 part by mass or more, moldability is improved, and when it is 1.0 part by mass or less, flexibility is excellent.

[0041] The thermoplastic elastomer resin composition of the present invention preferably contains a sliding agent (E). Specific examples of the sliding agent (E) used in the present invention include polyolefin wax, organopolysiloxane, polyalkylene glycol, higher alcohol, fatty acid, fatty acid amide, fatty acid metal salt, polytetrafluoroethylene, etc., with polyolefin wax and organopolysiloxane being particularly preferred.

[0042] The polyolefin wax is preferably an acid-modified ethylene / α-olefin copolymer, and the organopolysiloxane is preferably a silicone oil such as dimethyl silicone, methylphenyl silicone, or methylhydrogen silicone.

[0043] The content of the sliding agent (E) is preferably 0.05 to 3.0 parts by mass, more preferably 0.1 to 2.5 parts by mass, and even more preferably 0.5 to 2.0 parts by mass, relative to 100 parts by mass of the thermoplastic elastomer resin composition. By setting the content of the sliding agent (E) to 0.05 parts by mass or more, the surface layer of the molded article can be improved, and by setting it to 3.0 parts by mass or less, bleeding out can be suppressed.

[0044] To the thermoplastic elastomer resin composition of the present invention, additives and reinforcing agents such as antioxidants, ultraviolet absorbers, light stabilizers, antistatic agents, lubricants, dyes, pigments, plasticizers, flame retardants, mold release agents, glass fibers, metal fibers, carbon fibers, and metal flakes may be added as needed, provided that the object of the composition is not impaired.

[0045] The thermoplastic elastomer resin composition of the present invention preferably has a surface hardness (H) of 60D to 40D, more preferably 55D to 43D, and particularly preferably 50D to 45D, when measured in accordance with JIS K7215: 1986. If the surface hardness (H) exceeds 60D, the sound deadening properties will be insufficient, and if it is less than 40D, it will deform during product assembly, which is undesirable.

[0046] The thermoplastic elastomer resin composition of the present invention has a flexural modulus (M) of 200 MPa or more, preferably 235 MPa or more, as measured in accordance with ASTM D 790. If the flexural modulus (M) is less than 200 MPa, the strength as a component may be insufficient or the component may be deformed during assembly into a product, which is not preferred.

[0047] In the thermoplastic elastomer resin composition of the present invention, the flexural modulus (M) (unit: MPa) measured in accordance with ASTM D790 and the surface hardness (H) (unit: D) ​​measured by durometer D in accordance with JIS K7215: 1986 preferably satisfy the relationship shown in formula (i). If formula (i) is not satisfied, the surface hardness may be small and the flexural modulus may be small, resulting in excellent sound-deadening properties, but the strength as a member may be insufficient, or the flexural modulus may be large and the strength as a member may be excellent, but the surface hardness may be large and the sound-deadening properties may be insufficient, which is not preferable. (M)>18×(H)-665 ···(i) The difference between the melting point and the crystallization temperature of the thermoplastic elastomer resin composition of the present invention is preferably 35° C. or less, and more preferably 30° C. or less. If the difference between the melting point and the crystallization temperature exceeds 35° C., solidification will be slow, the molding cycle will be long, and the molded product will be deformed by the ejector pin, which is not preferable.

[0048] The melt viscosity index (MFR) of the thermoplastic elastomer resin composition of the present invention is a value measured in accordance with ASTM D1238. Because the melting point varies depending on the type of thermoplastic elastomer resin composition, the measurement temperature must be appropriately set; as a guideline, it is set at the melting point of the thermoplastic elastomer resin composition + 30°C. The MFR of the thermoplastic elastomer resin composition of the present invention is preferably 1 to 60 g / 10 min, more preferably 5 to 55 g / 10 min, and even more preferably 10 to 50 g / 10 min. An MFR of less than 1 g / 10 min is undesirable because the composition will have low fluidity and insufficient moldability, while an MFR of more than 60 g / 10 min is undesirable because the composition will tend to have poor mechanical properties.

[0049] The mold shrinkage of the thermoplastic elastomer resin composition of the present invention is calculated by measuring the dimensions of a JIS No. 2 dumbbell test piece obtained by injection molding with a vernier caliper, and dividing the difference (shrinkage amount) between the measured dimensions and the mold dimensions corresponding to that position by the mold dimensions. The mold shrinkage of the thermoplastic elastomer resin composition of the present invention is 0.30 to 1.20%, preferably 0.40 to 1.10%, and more preferably 0.50 to 1.00%. A mold shrinkage of more than 1.20% results in insufficient dimensional precision of the molded product, while a mold shrinkage of less than 0.30% is undesirable because it deteriorates releasability from the mold.

[0050] The dynamic friction coefficient of the thermoplastic elastomer resin composition of the present invention is preferably 0.40 or less, more preferably 0.35 or less, and even more preferably 0.30 or less. A dynamic friction coefficient exceeding 0.40 is undesirable because it deteriorates the abrasion resistance.

[0051] The sound deadening properties of the thermoplastic elastomer resin composition of the present invention were evaluated by a falling ball noise test. The falling ball noise of the thermoplastic elastomer resin composition of the present invention is 95 dB or less, preferably 90 dB or less, and more preferably 85 dB or less. [Example]

[0052] The effects of the present invention will be explained below with reference to examples. In the examples, % and parts are all by mass unless otherwise specified. The properties shown in the examples were measured as follows.

[0053] [Surface hardness (Durometer D)] The surface hardness was measured using a durometer D in accordance with JIS K7215:1986.

[0054] [Melting point measurement] Using a TA Instruments DSC Q100, the melting point was measured by heating from room temperature to 240°C at a heating rate of 10°C / min. After holding at 240°C for 3 minutes, the sample was cooled to 40°C at a heating rate of 10°C / min to measure the crystallization temperature.

[0055] [Flexural modulus (unit: MPa)] Flexural modulus was measured according to ASTM D790.

[0056] [Melt viscosity index (MFR)] According to ASTM D1238, the thermoplastic elastomer resin compositions of the following Examples and Comparative Examples were measured at a melting point of +30°C and a load of 2160 g.

[0057] [Mold shrinkage rate] JIS No. 2 dumbbell test pieces were molded under the conditions of a cylinder temperature (melting point + 30)°C, a mold temperature of 50°C, and a cooling time of 10 seconds. The dimensions of the JIS No. 2 dumbbell test pieces released from the mold by the ejector were measured with a vernier caliper, and the difference between the mold dimensions corresponding to that position (amount of shrinkage) was divided by the mold dimensions to calculate the value.

[0058] [Dynamic friction coefficient] The dynamic friction coefficient was measured under the following conditions. <Measurement conditions> Load: 100g Speed: 30mm / sec Analysis range: 5mm-25mm Testing machine: Friction testing machine (manufactured by Trinity Lab) Test environment: 23°C x 50% RH Test piece: Square injection molded plate (125mm x 75mm x 2mm thick) Test method: Fix the test piece to the testing machine, place the metal terminal in the center of the test piece, place the specified weight on it, and start measuring at the specified speed.

[0059] [Falling ball noise] A square injection molded plate measuring 125mm x 75mm x 2mm thick was placed on an aluminum plate measuring 150mm x 100mm x 10mm thick, and a φ9.5mm stainless steel ball was dropped onto the centre of the square injection molded plate from a height of 200mm. The noise level was measured with a sound level meter at a position 140mm away from the impact point (point of drop).

[0060] [Strand Stability] The thermoplastic elastomer resin composition was melt-kneaded using a twin-screw extruder with a 45 mm diameter screw, and the resulting composition was extruded into water in the form of a strand, which was then cut into pellets. The state of the strand was observed 5 minutes after extrusion began and the strand was placed in the guide groove. The stability of the strand at this time was evaluated as follows: ○: The strand does not come out of the guide groove at all. ×: The strands may break and become impossible to pull.

[0061] [Reference example] [Production of Polyester Block Copolymer (A-1)] 419 parts of terephthalic acid, 397 parts of 1,4-butanediol, and 476 parts of poly(tetramethylene oxide) glycol with a number-average molecular weight of approximately 1400 were charged into a reaction vessel equipped with a helical ribbon impeller, along with 0.3 parts of titanium tetrabutoxide and 0.1 parts of mono-n-butyl-monohydroxytin oxide. The mixture was heated at 190-225°C for 3 hours, allowing the esterification reaction to proceed while the reaction water was removed from the system. After adding 2.0 parts of titanium tetrabutoxide and 0.5 parts of "Irganox" 1098 (a hindered phenol-based antioxidant manufactured by BASF), the mixture was heated to 245°C. The pressure in the system was then reduced to 27 Pa over 50 minutes, and polymerization was carried out under these conditions for 1 hour and 50 minutes. The resulting polymer was extruded into water in strand form and pelletized by cutting. The surface hardness of this polyester block copolymer was 47D.

[0062] [Production of Polyester Block Copolymer (A-2)] 359 parts of terephthalic acid, 321 parts of 1,4-butanediol, and 610 parts of poly(tetramethylene oxide) glycol with a number-average molecular weight of approximately 1400 were charged into a reactor equipped with a helical ribbon impeller, along with 0.3 parts of titanium tetrabutoxide and 0.1 parts of mono-n-butyl-monohydroxytin oxide. The mixture was heated at 190-225°C for 3 hours to carry out an esterification reaction while distilling off the reaction water. After adding 2.0 parts of titanium tetrabutoxide and 0.5 parts of "Irganox" 1098 (a hindered phenol-based antioxidant manufactured by BASF), the mixture was heated to 245°C, and the pressure in the system was reduced to 0.2 mmHg over 50 minutes. Melt polycondensation was carried out under these conditions for 2 hours and 45 minutes. The resulting polyester elastomer was extruded into water in the form of strands and cut into pellets. The surface hardness of this polyester block copolymer was 40D.

[0063] [Production of Polyester Block Copolymer (A-3)] 234 parts of terephthalic acid, 228 parts of 1,4-butanediol, and 754 parts of poly(tetramethylene oxide) glycol with a number-average molecular weight of approximately 2000 were charged into a reaction vessel equipped with a helical ribbon impeller, along with 0.2 parts of titanium tetrabutoxide. The mixture was heated at 190-225°C for 3 hours to carry out an esterification reaction while distilling off the reaction water. After adding 0.5 parts of "Irganox" 1330 (a hindered phenol-based antioxidant manufactured by BASF Corporation), the reaction mixture was heated to 245°C. The pressure in the system was then reduced to 0.2 mmHg over 50 minutes, and melt polycondensation was carried out under these conditions for 3 hours and 30 minutes. The resulting polyester elastomer was extruded into water in the form of strands and cut into pellets. The surface hardness of this polyester block copolymer was 30D.

[0064] [Production of Polyester Block Copolymer (A-4)] 505 parts of terephthalic acid, 251 parts of 1,4-butanediol, and 354 parts of poly(tetramethylene oxide) glycol with a number-average molecular weight of approximately 1400 were charged into a reaction vessel equipped with a helical ribbon impeller, along with 0.4 parts of titanium tetrabutoxide and 0.2 parts of mono-n-butyl-monohydroxytin oxide. The mixture was heated at 190-225°C for 3 hours to carry out an esterification reaction while distilling off the reaction water. After adding 2.0 parts of titanium tetrabutoxide and 0.5 parts of "Irganox" 1098 (a hindered phenol-based antioxidant manufactured by BASF), the mixture was heated to 245°C, and the pressure in the system was reduced to 0.2 mmHg over 50 minutes. Melt polycondensation was carried out under these conditions for 2 hours and 45 minutes. The resulting polyester elastomer was extruded into water in the form of strands and cut into pellets. The surface hardness of this polyester block copolymer was 55D.

[0065] [Production of Polyester Block Copolymer (A-5)] 340 parts of terephthalic acid, 100 parts of isophthalic acid, 394 parts of 1,4-butanediol, and 495 parts of poly(oxytetramethylene) glycol with a number-average molecular weight of approximately 1400 were charged into a reaction vessel equipped with a helical ribbon stirrer along with 0.3 parts of titanium tetrabutoxide and 0.1 parts of mono-n-butyl-monohydroxytin oxide. The mixture was heated at 190-225°C for 3 hours, allowing the esterification reaction to proceed while the reaction water was drained out of the system. To the reaction mixture, 2.0 parts of tetra-n-butyl titanate and 0.5 parts of "Irganox" 1098 (a hindered phenol-based antioxidant manufactured by BASF) were added, and the temperature was raised to 245°C. The pressure in the system was then reduced to 27 Pa over 50 minutes, and polymerization was carried out under these conditions for 1 hour and 50 minutes. The resulting polymer was extruded into water in the form of strands and cut into pellets. The surface hardness of this polyester block copolymer (A-5) was 40D.

[0066] [Production of Rubber Graft Copolymer (B)] In the presence of 60 parts (solids content) of polybutadiene latex, 40 parts of a monomer mixture consisting of 70% styrene and 30% acrylonitrile was continuously added dropwise over 4 hours to carry out emulsion polymerization. The resulting polymer was coagulated with sulfuric acid, neutralized with caustic soda, washed, filtered, and dried to obtain a powdery rubbery polymer. The graft ratio of this rubbery polymer was 39%.

[0067] [Vinyl copolymer (C)] Toray Industries, Inc.'s AS resin "Toyolac" A25C-300 was used.

[0068] [Inorganic materials (D)] The plate-shaped filler used was "Talc Hitron," a magnesium silicate manufactured by Takehara Chemical Industry Co., Ltd.

[0069] [Sliding agent (E-1)] The low molecular weight polyethylene "Hiwax" 1105A manufactured by Mitsui Chemicals, Inc. was used.

[0070] [Sliding agent (E-2)] The silicone content of the polyether ester block copolymer "BY27-010" manufactured by Dow Corning Toray Co., Ltd. was 50%.

[0071] [Examples 1 to 12] and [Comparative Examples 1 to 8] The polyester block copolymers (A-1), (A-2), (A-3), (A-4), and (A-5) obtained in the Reference Examples, the rubbery graft copolymer (B), the vinyl copolymer (C), the inorganic material (D), and the sliding agents (E-1) and (E-2) were dry-blended in the blending ratios (mass%) shown in Table 1, and the mixture was melt-kneaded at 200°C to 240°C using a twin-screw extruder with a 45 mm diameter, triple-start screw, and pelletized.

[0072] These pellets were dried at 80°C for 5 hours and then injection-molded using an electric injection molding machine (NEX-1000) manufactured by Nissei Plastic Industrial Co., Ltd., at a cylinder temperature of (melting point + 30)°C and a mold temperature (mold cavity surface) of 50°C to form JIS No. 2 dumbbell test pieces measuring 125mm long x 75mm wide x 2mm thick and bending test pieces measuring 129mm long x 12.8mm wide x 6.3mm thick. The properties of each test were examined and the results are shown in Table 1.

[0073] [Table 1]

[0074] From the above results, it can be seen that the thermoplastic elastomer resin compositions of the present invention, which are blends of the polyester block copolymer (A), the specific rubbery graft copolymer (B), and the vinyl copolymer (C) shown in Examples 1 to 12, have low surface hardness and excellent sound-deadening properties, and also have a high flexural modulus and sufficient strength for use as components. Furthermore, they have low molding shrinkage, and molded articles can be obtained with high dimensional accuracy even when they have complex shapes. Furthermore, the resin composition has excellent strand stability during melt-kneading, allowing the formation of pellets with uniform shapes.

[0075] On the other hand, the thermoplastic elastomer resin compositions of Comparative Examples 1 to 8, which do not satisfy the conditions of the present invention, were inferior in any of the sound deadening properties, flexural modulus, molding shrinkage, and strand stability during melt kneading.

[0076] The use of polyester block copolymer (A-1) alone, as in Comparative Example 1, is undesirable because it has a low flexural modulus and a large mold shrinkage. It also does not satisfy formula (i). Comparative Example 2, in which polyester block copolymer (A-1) and a specific rubbery graft copolymer (B) are blended, is also undesirable for the same reasons as Comparative Example 1. Comparative Example 3, in which polyester block copolymer (A-1) and vinyl copolymer (C) are blended, has a high flexural modulus and a reduced mold shrinkage, but is undesirable because strand stability during melt-kneading deteriorates. Comparative Example 4, in which the blending amount of vinyl copolymer (C) is small, is undesirable because it has a large mold shrinkage. Comparative Example 5, in which polyester block copolymer (A-2) is used and the blending amount of vinyl copolymer (C) is small, is undesirable because it has a large mold shrinkage. Comparative Example 6, in which polyester block copolymer (A-3) is used and the blending amount of vinyl copolymer (C) is small, is undesirable because it has a small flexural modulus. Comparative Example 7, which uses polyester block copolymer (A-4) and contains a small amount of vinyl copolymer (C), is undesirable because it has poor sound-absorbing properties and a large molding shrinkage rate, while Comparative Example 8, which contains a large amount of vinyl copolymer (C), is undesirable because it has poor sound-absorbing properties and deteriorates strand stability during melt-kneading.

Claims

1. 1. A thermoplastic elastomer resin composition comprising: a polyester block copolymer (A) having as its main components a high-melting-point crystalline polymer segment (a) composed of crystalline aromatic polyester units; and a low-melting-point polymer segment (b) composed of aliphatic polyether units; a rubbery graft copolymer (B) obtained by copolymerizing a vinyl monomer containing an aromatic vinyl monomer and a vinyl cyanide monomer as main components in the presence of a rubbery polymer; and a vinyl copolymer (C) composed of an aromatic vinyl monomer and a vinyl cyanide monomer, wherein the thermoplastic elastomer resin composition contains 50 to 79% by mass of the polyester block copolymer (A), 1 to 15% by mass of the rubbery graft copolymer (B), and 20 to 35% by mass of the vinyl copolymer (C) relative to 100% by mass of the total of the polyester block copolymer (A), the rubbery graft copolymer (B), and the vinyl copolymer (C).

2. 2. The thermoplastic elastomer resin composition according to claim 1, wherein the flexural modulus (M) (unit: MPa) measured in accordance with ASTM D790 and the surface hardness (H) (unit: D) ​​measured by durometer D in accordance with JIS K7215:1986 satisfy the relationship of formula (i). (M)>18×(H)-665...(i)

3. 3. The thermoplastic elastomer resin composition according to claim 1, which has a flexural modulus (M) of 235 MPa or more when measured in accordance with ASTM D790.

4. 3. The thermoplastic elastomer resin composition according to claim 1, wherein the mass ratio of the high-melting point crystalline polymer segment (a) to the low-melting point polymer segment (b) in the polyester block copolymer (A) is 55 / 45 to 20 / 80.

5. 3. The thermoplastic elastomer resin composition according to claim 1, further comprising 0.05 to 1.0 parts by mass of an inorganic material (D) relative to 100 parts by mass of the thermoplastic elastomer resin composition.

6. 3. The thermoplastic elastomer resin composition according to claim 1, further comprising 0.05 to 3.0 parts by mass of a sliding agent (E) relative to 100 parts by mass of the thermoplastic elastomer resin composition.

7. 3. The thermoplastic elastomer resin composition according to claim 1, wherein the rubbery graft copolymer (B) is obtained by graft polymerizing 40 to 85 parts by mass of a diene rubbery polymer and 15 to 60 parts by mass of a vinyl monomer containing an aromatic vinyl monomer and a vinyl cyanide monomer as main components so that the total amount is 100 parts by mass, and the graft ratio of the vinyl monomer is 25% or more.

Images