Thermoplastic polyester elastomer resin composition

Abstract

The present invention provides a thermoplastic polyester elastomer resin composition that has high acid resistance, heat aging resistance, copper damage resistance, flexibility, and flame retardancy, and that is suitable for automotive components, particularly for an automotive cable coating material.　The thermoplastic polyester elastomer resin composition contains a thermoplastic polyester elastomer (A) and an olefinic elastomer (B). The thermoplastic polyester elastomer (A) is formed by bonding hard segments and soft segments. The hard segments are composed of a polyester having an aromatic dicarboxylic acid and an aliphatic or an alicyclic diol as constituent components. The soft segments contain an aliphatic polycarbonate. The olefinic elastomer (B) has an aromatic vinyl polymer block and a C3-20 alkene as a monomer component and does not contain a conjugated diene as a monomer component. Relative to the total amount of the thermoplastic polyester elastomer (A) and the olefinic elastomer (B), the content of the thermoplastic polyester elastomer (A) is 50-90 mass% and the content of the olefinic elastomer (B) is 10-50 mass%. The thermoplastic polyester elastomer resin composition contains 0-5 mass parts of an acid end capping agent (C) and 7-33 mass parts of a flame retardant (D) per 100 total mass parts of the thermoplastic polyester elastomer (A) and the olefinic elastomer (B).

Description

Thermoplastic polyester elastomer resin composition

[0001] The present invention relates to a thermoplastic polyester elastomer resin composition, and more particularly to a thermoplastic polyester elastomer resin composition useful as a coating material for automobile parts, particularly for cables such as on-board cables.

[0002] Thermoplastic polyester elastomers have been known as molding materials for automobile parts, which are obtained by bonding together a hard segment made of a crystalline polyester such as polybutylene terephthalate (PBT) or polybutylene naphthalate (PBN) and a soft segment made of a polyoxyalkylene glycol such as polytetramethylene glycol (PTMG) and / or a polyester such as polycaprolactone (PCL) or polybutylene adipate (PBA) (see Patent Documents 1 and 2).

[0003] However, polyester-polyether type elastomers using polyoxyalkylene glycols in the soft segment are known to have excellent water resistance and low-temperature properties but poor heat aging resistance, while polyester-polyester type elastomers using polyesters in the soft segment are known to have excellent heat aging resistance but poor water resistance and low-temperature properties.

[0004] To solve these problems, polyester-polycarbonate elastomers using polycarbonate in the soft segment have been proposed (see Patent Documents 3 to 8). These polyester-polycarbonate elastomers have excellent heat aging resistance and are therefore used in applications such as automobile engine peripheral components.

[0005] In the automotive industry, electric vehicles are expected to replace conventional gasoline-powered vehicles in the future. Due to their high heat aging resistance and flexibility, polyester-polycarbonate elastomers are expected to be used as next-generation in-vehicle cable coating materials for electric vehicles. To be used in this application, they must pass a battery fluid (sulfuric acid) drop test and also have excellent flame retardancy. However, conventional polyester-polycarbonate elastomers have not been able to pass the sulfuric acid drop test or flame retardancy test.

[0006] Therefore, it has been proposed to improve acid resistance by blending inorganic fillers or olefin-based elastomers with polyester-polycarbonate elastomers (see Patent Documents 9 and 10). While these methods can improve acid resistance to a certain extent, the heat aging resistance and copper damage resistance (heat aging resistance in contact with a copper plate) are insufficient, and there is still room for improvement before these materials can be used practically as coating materials for in-vehicle cables. Furthermore, these materials may also be required to be flame retardant.

[0007] JP 10-017657 JP 2003-192778 JP 07-039480 JP 05-295049 JP 06-306202 JP 10-182782, JP 2001-206939, JP 2001-240663, JP 2022-150988, WO 2022 / 202629

[0008] The present invention has been made in view of the above problems of the prior art, and its object is to provide a thermoplastic polyester elastomer resin composition that has excellent acid resistance, heat aging resistance, copper damage resistance, flexibility, and flame retardancy and is suitable for use as a coating material for automotive parts, particularly for in-vehicle cable. Another preferred object of the present invention is to provide a thermoplastic polyester elastomer resin composition that has excellent extrudability (extrusion moldability) in addition to the above properties.

[0009] As a result of extensive research to achieve the above object, the present inventors have found that by using an olefin-based elastomer having a specific structure that does not have a residual double bond in the molecule and a flame retardant in a thermoplastic polyester-polycarbonate type elastomer, acid resistance and flame retardancy can be improved and excellent heat aging resistance, copper damage resistance and flexibility can be achieved, thereby completing the present invention.

[0010] The present invention, which has solved the above-mentioned problems, has the following configuration: (1) A thermoplastic polyester elastomer resin composition containing a thermoplastic polyester elastomer (A) and an olefin-based elastomer (B), wherein the thermoplastic polyester elastomer (A) is formed by bonding hard segments and soft segments, the hard segments are made of a polyester having an aromatic dicarboxylic acid and an aliphatic or alicyclic diol as constituent components, the soft segments contain an aliphatic polycarbonate, and the olefin-based elastomer (B) is made of an aromatic vinyl polymer block and an alkene having 3 to 20 carbon atoms as monomer components, and a conjugated diene as monomer component. a content of the thermoplastic polyester elastomer (A) is 50 to 90 mass% and a content of the olefin-based elastomer (B) is 10 to 50 mass% relative to a total amount of the thermoplastic polyester elastomer (A) and the olefin-based elastomer (B); and the thermoplastic polyester elastomer resin composition contains 0 to 5 parts by mass of an acid end-capping agent (C) and 7 to 33 parts by mass of a flame retardant (D) relative to 100 parts by mass of the total of the thermoplastic polyester elastomer (A) and the olefin-based elastomer (B).

[0011] (2) The thermoplastic resin composition according to (1), wherein the flame retardant (D) is a brominated flame retardant. (3) The thermoplastic polyester elastomer resin composition according to (1) or (2), wherein the olefin elastomer (B) comprises a copolymer of an aromatic vinyl polymer block and isobutene. (4) The thermoplastic polyester elastomer resin composition according to any one of (1) to (3), wherein the flame retardant (D) is an amorphous brominated flame retardant or a brominated flame retardant having a melting point of 270°C or less.

[0012] (5) The thermoplastic polyester elastomer resin composition according to any one of (1) to (4), characterized in that the corrosion depth of the thermoplastic polyester elastomer resin composition measured in accordance with an acid resistance test method is 1.2 mm or less. (6) The thermoplastic polyester elastomer resin composition according to any one of (1) to (5), characterized in that the elongation at break of the thermoplastic polyester elastomer resin composition measured in accordance with a heat aging resistance test method is 100% or more. (7) The thermoplastic polyester elastomer resin composition according to any one of (1) to (6), characterized in that the elongation at break of the thermoplastic polyester elastomer resin composition measured in accordance with a copper damage resistance test method is 100% or more. (8) The thermoplastic polyester elastomer resin composition according to any one of (1) to (7), characterized in that the hardness of the thermoplastic polyester elastomer resin composition measured in accordance with the hardness test method for thermoplastics specified in ASTM D 2240 is D30 to D50.

[0013] (9) The thermoplastic polyester elastomer resin composition according to any one of (1) to (8), characterized in that the thermoplastic polyester elastomer (A) has a melting point of 150 to 225°C, and the melting point difference (Tm1 - Tm3) between the melting point (Tm1) of the thermoplastic polyester elastomer (A) measured at the first temperature decrease in a procedure in which a differential scanning calorimeter is used to increase the temperature from room temperature to 300°C at a temperature increase rate of 20°C / min, maintain the temperature at 300°C for 3 minutes, and then decrease the temperature to room temperature at a temperature decrease rate of 100°C / min, is repeated three times, and the melting point difference (Tm1 - Tm3) between the melting point (Tm1) of the thermoplastic polyester elastomer (A) measured at the third temperature decrease in the procedure is 0 to 50°C.

[0014] (10) The thermoplastic polyester elastomer resin composition according to any one of (1) to (9), wherein the content of terephthalic acid and / or naphthalenedicarboxylic acid in all dicarboxylic acids constituting the polyester of the hard segment is 70 mol% or more. (11) The thermoplastic polyester elastomer resin composition according to any one of (1) to (10), wherein the thermoplastic polyester elastomer (A) has a terminal acid value of 60 eq / ton or less. (12) The thermoplastic polyester elastomer resin composition according to any one of (1) to (11), wherein the thermoplastic polyester elastomer (A) has a reduced viscosity of 0.5 to 4.0 dl / g. (13) The thermoplastic polyester elastomer resin composition according to any one of (1) to (12), further comprising a flame retardant aid. (14) The thermoplastic polyester elastomer resin composition according to (13), wherein the flame retardant aid is an antimony oxide compound.

[0015] (15) The thermoplastic polyester elastomer resin composition according to any one of (1) to (14), characterized in that the thermoplastic polyester elastomer resin composition is for extrusion molding. (16) The thermoplastic polyester elastomer resin composition according to any one of (1) to (14), characterized in that the thermoplastic polyester elastomer resin composition is for cable coating.

[0016] According to the present invention, a thermoplastic polyester elastomer resin composition having excellent acid resistance, heat aging resistance, copper damage resistance, flexibility, and flame retardancy can be provided. Because the thermoplastic polyester elastomer resin composition of the present invention has these properties, it can be suitably used as a material for coating automotive parts, particularly automotive cables. Furthermore, according to a preferred embodiment of the present invention, a thermoplastic polyester elastomer resin composition having not only the above properties but also excellent extrudability (extrusion moldability) can be provided, and therefore it can be suitably used as a material for extrusion molding of various parts.

[0017] The thermoplastic polyester elastomer resin composition of the present invention will be described in detail below. In this specification, the notation "A to B" means the upper and lower limits of a range (i.e., A or more and B or less). When no unit is specified for A and only a unit is specified for B, the units of A and B are the same.

[0018] The thermoplastic polyester elastomer resin composition of the present invention contains a polyester-polycarbonate type thermoplastic polyester elastomer (A) and an olefinic elastomer (B), and optionally further contains an acid end-capping agent (C) and a flame retardant (D). In the present invention, by using an olefinic elastomer with a specific structure that does not have residual double bonds in the molecule as the olefinic elastomer (B), the thermoplastic polyester elastomer resin composition exhibits excellent acid resistance, flame retardancy, heat aging resistance, and copper damage resistance. Each of the constituent components of the thermoplastic polyester elastomer resin composition of the present invention will be described below in order.

[0019] <Thermoplastic polyester elastomer (A)> The thermoplastic polyester elastomer (A) is a copolymer formed by bonding hard segments and soft segments. The soft segments contain aliphatic polycarbonate. In this specification, the term "bonded" between hard segments and soft segments refers to both a state in which the hard segments and soft segments are bonded via a chain extender such as an isocyanate compound, and a state in which the structural units of the hard segments and soft segments are directly bonded via an ester bond and / or a carbonate bond. Among these, it is preferable that the structural units of the hard segments and soft segments are directly bonded via an ester bond and / or a carbonate bond.

[0020] (Hard Segment) The hard segment is composed of a polyester composed of an aromatic dicarboxylic acid (sometimes referred to as an acid component) and an aliphatic or alicyclic diol (sometimes referred to as a diol component). The aromatic dicarboxylic acid is not particularly limited, and any conventionally known aromatic dicarboxylic acid can be used. For example, at least one selected from the group consisting of terephthalic acid and naphthalenedicarboxylic acid is preferred. Furthermore, 2,6-naphthalenedicarboxylic acid is preferred as the naphthalenedicarboxylic acid. Dicarboxylic acids other than the above aromatic dicarboxylic acids (other acid components) may be included. Examples of other acid components include aromatic dicarboxylic acids other than the above terephthalic acid and naphthalenedicarboxylic acid (other aromatic dicarboxylic acids), aliphatic dicarboxylic acids, and alicyclic dicarboxylic acids. Examples of other aromatic dicarboxylic acids include diphenyldicarboxylic acid, isophthalic acid, and 5-sodium sulfoisophthalic acid. Examples of aliphatic dicarboxylic acids include succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, dimer acid, and hydrogenated dimer acid. Examples of alicyclic dicarboxylic acids include cyclohexanedicarboxylic acid and tetrahydrophthalic anhydride.

[0021] The content of terephthalic acid and / or naphthalenedicarboxylic acid in all dicarboxylic acids constituting the polyester of the hard segment is preferably 70 mol% or more, more preferably 80 mol% or more, and even more preferably 100 mol%. The remainder of the content of terephthalic acid and / or naphthalenedicarboxylic acid in all dicarboxylic acids may contain the above-mentioned other acid components. The other acid components can be used in a range that does not significantly lower the melting point of the thermoplastic polyester elastomer (A). Specifically, the content of the other acid components in all dicarboxylic acids is preferably 30 mol% or less, more preferably 20 mol% or less.

[0022] The diol component constituting the polyester of the hard segment is an aliphatic diol or an alicyclic diol. The aliphatic diol and the alicyclic diol are not particularly limited, but alkylene glycols having 2 to 8 carbon atoms are preferred. Suitable examples of aliphatic diols include ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, and 1,6-hexanediol. Suitable examples of alicyclic diols include 1,4-cyclohexanedimethanol. Among these, ethylene glycol or 1,4-butanediol is preferred. The aliphatic diol and the alicyclic diol may be used alone or in combination, and the compounds exemplified above may be used alone or in combination.

[0023] The constituent components of the polyester are preferably butylene terephthalate-derived constituent units (constituent units derived from terephthalic acid and 1,4-butanediol) or butylene naphthalate-derived constituent units (constituent units derived from 2,6-naphthalenedicarboxylic acid and 1,4-butanediol). These constituent units are preferred from the viewpoints of the physical properties, moldability, and cost performance of the thermoplastic polyester elastomer resin composition.

[0024] The thermoplastic polyester elastomer (A) can be prepared by first preparing an aromatic polyester suitable as a polyester constituting the hard segment, and then copolymerizing it with the soft segment component described below. In this case, the aromatic polyester can be easily obtained according to a conventional polyester production method. The polyester constituting the hard segment preferably has a number average molecular weight of 10,000 to 40,000.

[0025] (Soft Segment) The soft segment contains an aliphatic polycarbonate. Therefore, the thermoplastic polyester elastomer (A) of the present invention is a polyester-polycarbonate type elastomer. The aliphatic polycarbonate is preferably one comprising an aliphatic diol residue having 2 to 12 carbon atoms, such as ethylene 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 viewpoint of imparting flexibility and low-temperature properties to the thermoplastic polyester elastomer (A), the aliphatic polycarbonate preferably contains a structural unit derived from an aliphatic diol having 5 to 12 carbon atoms. These components may be used alone or in combination of two or more types as required, based on the examples described below.

[0026] The aliphatic polycarbonate diol used as a raw material for the aliphatic polycarbonate preferably has a low melting point (for example, 70°C or lower) and a low glass transition temperature (for example, -50°C or lower). For example, an aliphatic polycarbonate diol composed of structural units derived from 1,6-hexanediol is preferred because it has a low glass transition temperature of around -60°C and a melting point of around 50°C, resulting in good low-temperature properties. Furthermore, an aliphatic polycarbonate diol obtained by copolymerizing, for example, an appropriate amount of 3-methyl-1,5-pentanediol with the aliphatic polycarbonate diol has a slightly higher glass transition temperature than the aliphatic polycarbonate diol before copolymerization, but is preferred because it has a lower melting point or becomes amorphous and has good low-temperature properties. Furthermore, for example, an aliphatic polycarbonate diol made of 1,9-nonanediol and 2-methyl-1,8-octanediol is preferable because it has a melting point of about 30° C. and a glass transition temperature of about −70° C., which are sufficiently low, and therefore has particularly good low-temperature properties.

[0027] The aliphatic polycarbonate may be composed solely of a polycarbonate component, or may contain small amounts of other glycols, dicarboxylic acids, ester compounds, or ether compounds. Examples of such copolymerization components include glycols such as dimer diol, hydrogenated dimer diol, and modified versions thereof; dicarboxylic acids such as dimer acid and hydrogenated dimer acid; polyesters or oligoesters composed of aliphatic, aromatic, or alicyclic dicarboxylic acids and glycols; polyesters or oligoesters composed of ε-caprolactone; and polyalkylene glycols or oligoalkylene glycols such as polytetramethylene glycol and polyoxyethylene glycol. The soft segment is also preferably composed of an aliphatic polycarbonate. The copolymerization components may be contained to an extent that does not substantially impair the effects of the aliphatic polycarbonate segment.

[0028] In the thermoplastic polyester elastomer (A), the mass ratio of the hard segment to the soft segment (hard segment:soft segment) is preferably 30:70 to 95:5, more preferably 40:60 to 90:10, even more preferably 45:55 to 90:10, and most preferably 50:50 to 90:10.

[0029] Generally, in thermoplastic polyester elastomers, the higher the hard segment ratio, the better the acid resistance. On the other hand, the higher the hard segment ratio, the higher the hardness, which tends to impair flexibility and low-temperature properties. Therefore, in the thermoplastic polyester elastomer (A), the mass ratio of the hard segment to the soft segment is preferably within the above-mentioned range.

[0030] The thermoplastic polyester elastomer (A) can be produced by a known method, for example, by appropriately selecting from the following methods: a method of obtaining a reaction product by transesterification of a lower alcohol diester of a dicarboxylic acid, an excess amount of a low-molecular-weight glycol, and a soft segment component in the presence of a catalyst, and then polycondensing the resulting reaction product; a method of obtaining a reaction product by esterification of a dicarboxylic acid, an excess amount of a glycol, and a soft segment component in the presence of a catalyst, and then polycondensing the resulting reaction product; a method of preparing a hard segment polyester in advance, adding a soft segment component to the polyester, and randomizing the polyester through a transesterification reaction; a method of linking hard segments and soft segments with a chain linking agent; and a method of adding an ε-caprolactone monomer to a hard segment when poly(ε-caprolactone) is used for the soft segment.

[0031] In a preferred embodiment of the present invention, the melting point of the thermoplastic polyester elastomer (A) is preferably 150 to 225°C, more preferably 190 to 220°C. If the melting point is below the lower limit, the thermoplastic polyester elastomer (A) melts at high temperatures, which may limit its use in high-temperature environments. If the melting point is above the upper limit, the molding temperature becomes excessively high, which may lead to easy decomposition of the soft segment during molding, making it difficult to obtain the desired heat aging resistance.

[0032] The melting point (Tm) of the thermoplastic polyester elastomer (A) can be determined by the following method. That is, the thermoplastic polyester elastomer (A) is dried under reduced pressure at 50°C for 15 hours, and then measured using a differential scanning calorimeter at a temperature increase rate of 20°C / min from room temperature. The melting point (Tm) of the thermoplastic polyester elastomer (A) can be determined from the temperature at which the endothermic peak due to melting occurs. Note that the sample for measuring the melting point of the thermoplastic polyester elastomer (A) is prepared by weighing 10 mg into an aluminum pan and sealing it with an aluminum lid. The melting point measurement is performed under an argon atmosphere.

[0033] Furthermore, in a differential scanning calorimeter, the thermoplastic polyester elastomer (A) is heated from room temperature to 300°C at a heating rate of 20°C / min, held at 300°C for 3 minutes, and then cooled to room temperature at a heating rate of 100°C / min, and this cycle is repeated three times. The melting point difference (Tm1-Tm3) between the melting point (Tm1) of the thermoplastic polyester elastomer (A) measured at the first temperature drop and the melting point (Tm3) of the thermoplastic polyester elastomer (A) measured at the third temperature drop in this procedure is preferably 0 to 50°C. The melting point difference (Tm1-Tm3) is more preferably 0 to 40°C, and even more preferably 0 to 30°C.

[0034] The melting point difference is a measure of the thermoplastic polyester elastomer (A)'s ability to retain block properties. The smaller the melting point difference, the better the thermoplastic polyester elastomer (A) can be evaluated as having a superior ability to retain block properties. When the melting point difference of the thermoplastic polyester elastomer (A) is within the above range, molded articles with excellent quality uniformity can be obtained due to the excellent ability to retain block properties. When the melting point difference exceeds the above range, the ability to retain block properties deteriorates, and quality fluctuations during molding processing increase, which may result in a deterioration in the quality uniformity and recyclability of molded articles.

[0035] Specifically, the melting point difference (Tm1 - Tm3) of the thermoplastic polyester elastomer (A) can be determined by the following method. First, 10 mg of the thermoplastic polyester elastomer (A) dried under reduced pressure at 50°C for 15 hours is weighed into an aluminum pan and sealed with an aluminum lid to prepare a measurement sample. Next, the aluminum pan containing the sealed measurement sample is heated from room temperature to 300°C at a heating rate of 20°C / min in a nitrogen atmosphere using a differential scanning calorimeter, and held at 300°C for 3 minutes. Thereafter, the aluminum pan is immersed in liquid nitrogen for rapid cooling, and cooled to room temperature at a heating rate of 100°C / min. After leaving the sample at room temperature for 30 minutes, the differential scanning calorimeter is again used to heat the pan from room temperature to 300°C at a heating rate of 20°C / min. This cycle is repeated three times, and the melting point (Tm1) of the measurement sample (thermoplastic polyester elastomer (A)) measured at the time when the temperature is lowered to room temperature for the first time and the melting point (Tm3) of the measurement sample (thermoplastic polyester elastomer (A)) measured at the time when the temperature is lowered to room temperature for the third time are measured, whereby the melting point difference (Tm1-Tm3) can be determined.

[0036] Terminal Acid Value It is also a preferred embodiment to control the terminal acid value of the thermoplastic polyester elastomer (A) within an appropriate range. The terminal acid value of the thermoplastic polyester elastomer (A) is preferably 60 eq / ton or less, more preferably 50 eq / ton or less, even more preferably 45 eq / ton or less, even more preferably 40 eq / ton or less, and most preferably 10 eq / ton. While increasing the terminal acid value contributes to improving flexibility and moldability, if the terminal acid value is too high, it may lead to a decrease in the oxidation resistance, heat aging resistance, and even flame retardancy of the resin composition. For this reason, the terminal acid value is measured under the conditions described in the examples.

[0037] Reduced Viscosity It is also a preferred embodiment to control the reduced viscosity of the thermoplastic polyester elastomer (A) within an appropriate range. The reduced viscosity of the thermoplastic polyester elastomer (A) is preferably 0.5 to 4.0 dl / g, more preferably 0.7 to 3.5 dl / g, and even more preferably 1.0 to 2.5 dl / g. Increasing the reduced viscosity is preferable because it increases mechanical strength such as tensile strength, improves the durability of automotive parts and cable coating materials, and improves heat resistance and aging resistance. On the other hand, if the reduced viscosity is too high, moldability and processability may be reduced. The reduced viscosity is measured under the conditions described in the examples.

[0038] <Olefin-based elastomer (B)> The thermoplastic polyester elastomer resin composition of the present invention further contains an olefin-based elastomer (B) in addition to the thermoplastic polyester elastomer (A) described above. By containing the olefin-based elastomer (B), acid resistance can be imparted to the non-polar resin, and therefore the acid resistance of the thermoplastic polyester elastomer resin composition can be improved.

[0039] The olefin elastomer (B) has an aromatic vinyl polymer block (hard segment) and a rubber block (soft segment). The aromatic vinyl polymer block serves to form physical crosslinks and serve as crosslinking points, while the rubber block serves to impart elasticity.

[0040] The aromatic vinyl compound forming the aromatic vinyl polymer block (hard segment) is not particularly limited, and examples thereof include styrene, o-, m-, or p-methylstyrene, α-methylstyrene, β-methylstyrene, 2,6-dimethylstyrene, 2,4-dimethylstyrene, α-methyl-o-methylstyrene, α-methyl-m-methylstyrene, α-methyl-p-methylstyrene, β-methyl-o-methylstyrene, β-methyl-m-methylstyrene, β-methyl-p-methylstyrene, 2,4,6-trimethylstyrene, α-methyl-2,6-dimethylstyrene, α-methyl-2,4-dimethylstyrene, β-methyl-2,6-dimethylstyrene, β-methyl-2,4-dimethylstyrene, o-, m-, or p-chlorostyrene, 2 Examples of suitable chlorostyrenes include 2,4-dichlorostyrene, α-chloro-o-chlorostyrene, α-chloro-m-chlorostyrene, α-chloro-p-chlorostyrene, β-chloro-o-chlorostyrene, β-chloro-m-chlorostyrene, β-chloro-p-chlorostyrene, 2,4,6-trichlorostyrene, α-chloro-2,6-dichlorostyrene, α-chloro-2,4-dichlorostyrene, β-chloro-2,6-dichlorostyrene, β-chloro-2,4-dichlorostyrene, o-, m-, or p-t-butylstyrene, o-, m-, or p-methoxystyrene, o-, m-, or p-chloromethylstyrene, o-, m-, or p-bromomethylstyrene, styrene derivatives substituted with silyl groups, indene, and vinylnaphthalene. These may be used alone or in combination of two or more. Among these, from the viewpoint of compatibility with the thermoplastic elastomer, styrene, α-methylstyrene, or a mixture thereof is preferred.

[0041] The rubber block (soft segment) must be an α-olefin that does not contain a conjugated diene as a monomer component, and the α-olefin must be an alkene having 3 to 20 carbon atoms. Specific examples of alkenes having 3 to 20 carbon atoms include propylene, isobutene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-nonadecene, 1-eicosene, 3-methyl-1-butene, Examples of the olefin copolymer include 3-methyl-1-pentene, 3-ethyl-1-pentene, 4-methyl-1-pentene, 4-methyl-1-hexene, 4,4-dimethyl-1-hexene, 4,4-dimethyl-1-pentene, 4-ethyl-1-hexene, 3-ethyl-1-hexene, 9-methyl-1-decene, 11-methyl-1-dodecene, 12-ethyl-1-tetradecene, and combinations thereof. These may be used alone or in combination of two or more. Among these, isobutene is preferred from the viewpoints of acid resistance, heat aging resistance, and copper damage resistance.

[0042] Specifically, as the olefin-based elastomer (B) composed of these aromatic vinyl polymer blocks and rubber blocks, styrene-isobutylene-styrene block copolymers (SIBS) are preferred from the viewpoints of heat aging resistance, copper damage resistance, and acid resistance. The styrene block content in these styrene-based elastomers is preferably 10% by mass or more from the viewpoint of extrusion moldability. The styrene block has a skeleton similar to the component consisting of an aromatic dicarboxylic acid and an aliphatic or alicyclic diol, which constitutes the hard segment of the thermoplastic polyester elastomer (A). Therefore, the greater the amount of styrene block, the better the compatibility with the thermoplastic polyester elastomer (A) and the better the extrusion moldability. Furthermore, from the viewpoint of flexibility, the upper limit of the styrene block content is preferably 60% by mass or less, and more preferably 40% by mass or less. Styrene-isobutylene-styrene block copolymers (SIBS) can be easily synthesized, for example, by referring to JP-A 2003-12887. Styrene-isobutylene-styrene block copolymers (SIBS) are also available as commercial products, such as "SIBSTAR 062T," "SIBSTAR 073T," "SIBSTAR 102T," and "SIBSTAR 103T," manufactured by Kaneka Corporation.

[0043] The olefinic elastomer (B) used in the present invention does not contain a conjugated diene as a monomer component and therefore does not have residual double bonds in the molecule. Generally, double bonds are a point of attack for oxygen, which accelerates heat aging, and are a factor in causing molecular weight reduction. Therefore, olefinic elastomers containing a conjugated diene as a monomer component, such as butylene-based olefinic elastomers, are hydrogenated to remove remaining double bonds in the segments and improve heat aging resistance. However, hydrogenation alone cannot completely remove double bonds, and some double bonds remain in the segments. Therefore, butylene-based olefinic elastomers such as those disclosed in Patent Documents 9 and 10 have a significant number of residual double bonds in the molecule. In contrast, the olefinic elastomer (B) used in the present invention does not contain a conjugated diene as a monomer component and inherently does not have residual double bonds in the molecule, as described above. Therefore, it is believed that the olefinic elastomer (B) not only has excellent acid resistance, but also excellent heat aging resistance and copper damage resistance (heat aging resistance when in contact with a copper plate). Examples of conjugated dienes include butadiene, isoprene, 1,3-pentadiene, and 2,3-dimethyl-1,3-butadiene.

[0044] In terms of flame retardancy, a low amount of the olefinic elastomer (B) is preferable. When a resin composition containing an olefinic elastomer is heated, the resin decomposes and generates a flammable gas. When the flammable gas diffuses into the air, it reacts with oxygen in the air due to a heat source, causing combustion. When the generated radiant heat is transmitted to the resin, the resin is decomposed again, and the combustion spreads. When a high amount of the olefinic elastomer (B) is added, the combustion mechanism occurs repeatedly, resulting in a longer combustion time.

[0045] The olefinic elastomer (B) may be either an unmodified olefinic elastomer or an acid-modified olefinic elastomer, but the unmodified olefinic elastomer is preferred because it can suppress reaction with the acid end-capping agent. When an acid-modified olefinic elastomer (B) is blended, a reaction between the acid end-capping agent and the acid-modified portion of the olefinic elastomer (B) or between the acid end-capping agent and the acid terminal of the thermoplastic polyester elastomer (A) may occur in a complex manner, which may cause an extreme increase in viscosity and gelation, and may result in a deterioration in the appearance of the extrusion-molded product.

[0046] From the viewpoint of improving acid resistance, it is more preferable that the olefinic elastomer (B) has a high melt flow rate (MFR) (low viscosity). Specifically, the MFR of the olefinic elastomer (B) is preferably 0.1 g / 10 min or more. If the MFR is below the lower limit, the dispersibility of the olefinic elastomer (B) domains deteriorates, and the olefinic elastomer (B) particles are present in a coarse state in the matrix. As a result, the bypass effect obtained from the effective surface area and morphology of the olefinic elastomer (B), which exerts acid resistance, decreases, which may lead to a deterioration in acid resistance. Furthermore, poor dispersibility and spherical domains may cause surface roughness during extrusion. The MFR of the olefinic elastomer (B) is more preferably 0.5 g / 10 min or more, and even more preferably 5 g / 10 min or more. The MFR of the olefinic elastomer (B) is preferably 15 g / 10 min or less. The MFR of the olefin-based elastomer (B) is a value measured at a temperature of 230° C. and a load of 2.16 kg. The blending ratio of the thermoplastic polyester elastomer (A) and the olefin-based elastomer (B) in the thermoplastic polyester elastomer resin composition of the present invention is 50 to 90 mass % of the thermoplastic polyester elastomer (A) and 10 to 50 mass % of the olefin-based elastomer (B) relative to the total amount of the thermoplastic polyester elastomer (A) and the olefin-based elastomer (B). That is, when the total amount of the thermoplastic polyester elastomer (A) and the olefin-based elastomer (B) is 100 parts by mass, the mass ratio (A / B) of the thermoplastic polyester elastomer (A) to the olefin-based elastomer (B) is preferably 90 / 10 to 50 / 50, more preferably 80 / 20 to 50 / 50, even more preferably 75 / 25 to 50 / 50, still more preferably 60 / 40 to 50 / 50, and particularly preferably 58 / 42 to 52 / 48. If the amount of the olefin-based elastomer (B) added is less than the above lower limit, acid resistance may be insufficient, while if the amount of the olefin-based elastomer (B) added exceeds the above upper limit, flame retardancy may be deteriorated due to an increase in combustible components, and heat aging resistance, copper damage resistance, and extrusion moldability may be insufficient due to poor dispersion.

[0047] <Acid End-Capping Agent (C)> The thermoplastic polyester elastomer resin composition of the present invention may further contain an acid end-capping agent (C) to improve hydrolysis resistance and flex fatigue resistance through chain extension, if desired. Any compound having a functional group (e.g., a carboxyl group, an acid anhydride group, an epoxy group, a hydroxyl group, a carbodiimide group, or an oxazoline group) capable of reacting with the terminal functional groups (carboxyl groups and / or hydroxyl groups) of the thermoplastic polyester elastomer (A) can be used as the acid end-capping agent (C). In a preferred embodiment, an epoxy compound or a carbodiimide compound is used in the present invention, taking into account changes in melt viscosity during melt retention and reactivity with the acid end-functional groups of the thermoplastic polyester elastomer (A). The acid end-capping agents may be used alone or in combination of two or more.

[0048] When the thermoplastic polyester elastomer resin composition of the present invention contains an acid terminal blocking agent (C), the content thereof is up to 5 parts by mass, preferably up to 4 parts by mass, per 100 parts by mass of the total of the thermoplastic polyester elastomer (A) and the olefin-based elastomer (B). If the content of the acid terminal blocking agent (C) exceeds the above upper limit, deterioration of flame retardancy and deterioration of mechanical properties due to foreign matter effects may occur. Note that, when a high-molecular-weight thermoplastic polyester elastomer (A) that does not require chain extension or a thermoplastic polyester elastomer (A) with a sufficiently low terminal acid value is used as the thermoplastic polyester elastomer (A), the acid terminal blocking agent (C) may not be added. Therefore, in the present invention, the acid terminal blocking agent (C) may be added as needed, and therefore the content of the acid terminal blocking agent (C) is preferably 0 parts by mass. However, in another preferred embodiment, the acid terminal blocking agent (C) may be essential, for example, it may be more than 0 parts by mass.

[0049] <Flame Retardant (D)> Examples of the flame retardant (D) used in the present invention include halogen-based flame retardants and non-halogen-based flame retardants. Halogen-based flame retardants are preferred because they have a significant flame retardant effect due to their radical trapping effect in the gas phase. The halogen-based flame retardant is not particularly limited as long as it contains a halogen in its molecular structure. For example, chlorine-based flame retardants and bromine-based flame retardants are preferred, with bromine-based flame retardants being more preferred. The bromine-based flame retardant is not particularly limited for the purpose of exhibiting flame retardancy, but from the viewpoint of extrusion moldability, amorphous bromine-based flame retardants or those having a melting point of 270°C or less are particularly preferred. If the melting point of the bromine-based flame retardant is higher than the above upper limit, poor dispersion of the flame retardant may occur during extrusion molding, resulting in poor extrusion moldability. The term "amorphous" as used herein means that no clear melting peak appears when 10 mg of the flame retardant (D) is heated at 20°C / min using a nitrogen flow of 30 ml / min and measured using a differential scanning calorimeter (DSC). The melting point is the temperature at which a melting peak appears when the flame retardant (D) is measured using DSC by the above-mentioned method.

[0050] Examples of the brominated flame retardant used in the present invention include bis(dibromopropyl)tetrabromobisphenol A, bis(dibromopropyl)tetrabromobisphenol S, tris(dibromopropyl)isocyanurate, tris(tribromoneopentyl)phosphate, brominated polyphenylene ether (including poly(di)bromophenylene ether, etc.), brominated polystyrene (including polydibromostyrene, polytribromostyrene, crosslinked brominated polystyrene, etc.), brominated crosslinked aromatic polymers, brominated epoxy resins, brominated phenoxy resins, brominated styrene-maleic anhydride polymers, tris(tribromophenoxy)triazine, ethylenebistetrabromophthalimide, bis(pentabromophenyl)ethane, polybromophenylindane, TBBA polycarbonate, and polypentabromobenzyl acrylate. Among these brominated flame retardants, brominated polystyrene (including polydibromostyrene, polytribromostyrene, cross-linked brominated polystyrene, etc.) is preferred because it is amorphous or has a melting point of 270° C. or less. One type of flame retardant may be used, or two or more types may be used.

[0051] The content of the flame retardant is 7 to 33 parts by mass, preferably 12 to 33 parts by mass, and more preferably 13.5 to 25 parts by mass, per 100 parts by mass of the total of the thermoplastic polyester elastomer (A) and the olefin-based elastomer (B). Increasing the content of the flame retardant shortens the maximum burning time of the composition and improves flammability. In particular, when the content is 13.5 parts or more, the decrease in maximum burning time relative to the increase in the flame retardant content is small, and flame retardancy is stable. On the other hand, when the content of the flame retardant is more than 33 parts by mass, the effect of adding the flame retardant results in a loss of flexibility, and heat aging resistance and copper damage resistance are reduced (elongation at break is reduced).

[0052] <Flame Retardant Auxiliary (E)> In the present invention, from the viewpoint of further improving flame retardancy, it is also a preferred embodiment to use a flame retardant auxiliary (E) as needed. Antimony oxide compounds are preferably used as the flame retardant auxiliary (E). Examples of antimony oxide compounds include antimony trioxide, antimony pentoxide, and sodium antimonate. The content of the flame retardant auxiliary (E) is preferably 1 to 10 parts by mass per 100 parts by mass of the total of the thermoplastic polyester elastomer resin composition (A) and the olefin-based elastomer (B). By using the flame retardant auxiliary (E) in such an amount within this range in combination with a brominated flame retardant, a polyester elastomer resin composition with particularly excellent flame retardancy can be prepared.

[0053] <Other Components> The thermoplastic polyester elastomer resin composition of the present invention may contain various additives as needed, provided that the effects of the present invention are not impaired. Examples of such additives include resins other than thermoplastic polyester elastomers, thickeners, antioxidants, light stabilizers, coloring pigments, inorganic and organic fillers, coupling agents, tackiness improvers, quenchers, metal deactivators, and other stabilizers. The amounts of the various additives added can be appropriately selected within a range that does not impair the effects of the present invention, and amounts typically used in molding thermoplastic resins can be used. Meanwhile, the total amount of the thermoplastic polyester elastomer (A), olefinic elastomer (B), and flame retardant (D) in 100% by mass of the thermoplastic polyester elastomer resin composition of the present invention is preferably 75% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more.

[0054] The composition and composition ratio of the thermoplastic polyester elastomer resin composition of the present invention can be determined, for example, by calculating from the proton integral ratio of 1H-NMR measured by dissolving a sample in a solvent such as deuterated chloroform.

[0055] <Method for producing thermoplastic polyester elastomer resin composition> The thermoplastic polyester elastomer resin composition of the present invention can be obtained by applying a conventionally known method for producing this type of thermoplastic polyester elastomer resin composition, as long as the specific thermoplastic polyester elastomer (A) and the specific olefin-based elastomer (B) are blended in the above-mentioned ratio. For example, the thermoplastic polyester elastomer resin composition of the present invention can be obtained by charging the thermoplastic polyester elastomer (A), the olefin-based elastomer (B), the flame retardant (D), and, if necessary, other additives and other components into a co-rotating twin-screw extruder or the like, kneading them, and then pelletizing them.

[0056] <Characteristics of Thermoplastic Polyester Elastomer Resin Composition> The thermoplastic polyester elastomer resin composition of the present invention has excellent acid resistance. Specifically, the corrosion depth of the thermoplastic polyester elastomer resin composition measured in accordance with the acid resistance test method is 1.2 mm or less. The method for measuring the corrosion depth of the thermoplastic polyester elastomer resin composition using the acid resistance test method will be described below.

[0057] First, a 2 mm thick plate-shaped molded article is obtained from the thermoplastic polyester elastomer resin composition. Next, 8 μL of a 37% by mass aqueous sulfuric acid solution is dropped onto the surface of the molded article, followed by heat treatment at 90°C for 8 hours. Another 8 μL of a 37% by mass aqueous sulfuric acid solution is dropped onto the same location on the surface of the molded article, followed by heat treatment at 90°C for 16 hours. This cycle is repeated for a total of two cycles, and then the molded article is cut so as to include the area of ​​erosion caused by dropping the sulfuric acid aqueous solution, to obtain a cross section of the molded article. Finally, the depth of the erosion formed on the cross section of the molded article can be measured to determine the erosion depth of the thermoplastic polyester elastomer resin composition.

[0058] The thermoplastic polyester elastomer resin composition of the present invention can achieve a corrosion depth of 1.2 mm or less, further 0.9 mm or less, further 0.8 mm or less, and further 0.7 mm or less. Since the corrosion depth of the thermoplastic polyester elastomer resin composition of the present invention is equal to or less than the above upper limit, it has excellent acid resistance in the above-mentioned battery fluid (sulfuric acid) dropping test.

[0059] The thermoplastic polyester elastomer resin composition of the present invention has excellent flame retardancy. Specifically, the maximum combustion time of the thermoplastic polyester elastomer resin composition measured in accordance with the UL94 standard is preferably 30 seconds or less, more preferably 20 seconds or less, and even more preferably 10 seconds or less.

[0060] The thermoplastic polyester elastomer resin composition of the present invention has excellent heat aging resistance. Specifically, the thermoplastic polyester elastomer resin composition may have an elongation at break of 100% or more as measured in accordance with a heat aging resistance test method.

[0061] The thermoplastic polyester elastomer resin composition of the present invention can achieve an elongation at break of 100% or more, and even 200% or more. Since the thermoplastic polyester elastomer resin composition of the present invention has an elongation at break that is equal to or greater than the above-mentioned lower limit, it has excellent heat aging resistance in the above-mentioned heat aging resistance test.

[0062] The thermoplastic polyester elastomer resin composition of the present invention has excellent copper damage resistance, specifically, an elongation at break of 100% or more as measured in accordance with the copper damage resistance test method.

[0063] The thermoplastic polyester elastomer resin composition of the present invention can achieve an elongation at break of 100% or more, and even 200% or more. Since the thermoplastic polyester elastomer resin composition of the present invention has an elongation at break that is equal to or greater than the above-mentioned lower limit, it has excellent copper damage resistance in the copper damage resistance test described above.

[0064] The thermoplastic polyester elastomer resin composition of the present invention has a hardness of D30 to D50 measured in accordance with the hardness test method for thermoplastics specified in ISO 48-4, and is excellent in flexibility. In the present invention, the hardness of the thermoplastic polyester elastomer resin composition can be determined as follows in accordance with the hardness test method for thermoplastics specified in ISO 48-4.

[0065] First, a thermoplastic polyester elastomer resin composition is injected from an injection molding machine with a cylinder temperature set to 20°C above the melting point of the resin composition and a mold temperature set to 50°C to obtain an injection-molded product measuring 100 mm in length, 100 mm in width, and 2.0 mm in thickness. Next, a specified needle tip is dropped onto the injection-molded product, three of which are stacked in the thickness direction, in a 23°C environment, and the instantaneous value of the durometer hardness type D at this time is read. The hardness of the thermoplastic polyester elastomer resin composition can be determined from this instantaneous value of type D. The above hardness refers to the so-called surface hardness.

[0066] The hardness of the thermoplastic polyester elastomer resin composition of the present invention is preferably D30 to D50, more preferably D30 to D45, and even more preferably D30 to D40. When the hardness is within the above range, the thermoplastic polyester elastomer resin composition of the present invention is particularly suitable for applications such as cable coating. When the hardness exceeds the above upper limit, the thermoplastic polyester elastomer resin composition may lack flexibility. On the other hand, when the hardness is below the above lower limit, the thermoplastic polyester elastomer resin composition may become excessively soft, making it impossible to ensure the strength of the molded product.

[0067] <Effects> As described above, the thermoplastic polyester elastomer resin composition of the present invention has excellent acid resistance, flame retardancy, heat aging resistance, and copper damage resistance. Furthermore, it retains the inherent flexibility, moldability, chemical resistance, flex fatigue resistance, abrasion resistance, electrical properties, and other properties of thermoplastic polyester elastomers. Therefore, the thermoplastic polyester elastomer resin composition of the present invention can be used in a wide range of applications, including automotive parts, various electrical product components, hoses, tubes, and cable coating materials. Taking advantage of its excellent acid resistance, it is particularly suitable for use as a coating material for automotive cables. The thermoplastic polyester elastomer resin composition of the present invention is also suitable for extrusion molding of various automotive and electrical appliance components, and can be molded into various shapes by injection molding, transfer molding, blow molding, and other methods in addition to extrusion molding.

[0068] This application claims the benefit of priority from Japanese Application No. 2024-23529, filed on February 20, 2024. The entire contents of the specification of Japanese Application No. 2024-23529 are incorporated herein by reference.

[0069] The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. The measured values ​​described in the examples were measured by the following measurement methods.

[0070] <Hardness (Surface Hardness, Durometer Hardness Type D)> The surface hardness of the thermoplastic polyester elastomer resin compositions of each Example and Comparative Example was measured in a 23°C environment in accordance with the test method (Durometer Hardness Type D) described in ISO 48-4 as follows.

[0071] First, a thermoplastic polyester elastomer resin composition was injected from an injection molding machine with a cylinder temperature of 20°C above the melting point of the resin composition and a mold temperature of 50°C to obtain an injection-molded product measuring 100 mm in length, 100 mm in width, and 2.0 mm in thickness. Next, a specified needle tip was dropped onto the injection-molded product, three of which were stacked in the thickness direction, in an environment of 23°C, and the instantaneous value of Type D was read 15 seconds later. The 15-second value of Type D was taken as the hardness (surface hardness) of the resin composition. Note that surface hardness is an index of flexibility; the lower the surface hardness value, the better the flexibility.

[0072] <Acid Resistance (90° C. Dropping), That is, Measurement of Erosion Depth> In order to measure the erosion depth of the thermoplastic polyester elastomer resin compositions of each Example and Comparative Example, an acid resistance test was carried out as follows.

[0073] First, a 2 mm thick plate-shaped molded article was obtained from the thermoplastic polyester elastomer resin composition. Next, 8 μL of a 37% by mass aqueous sulfuric acid solution was dropped onto the surface of the molded article, followed by heat treatment at 90°C for 8 hours. Another 8 μL of a 37% by mass aqueous sulfuric acid solution was dropped onto the same location on the surface of the molded article, followed by heat treatment at 90°C for 16 hours. This cycle was repeated twice, and the molded article was then cut to include the erosion site caused by the dropping of the sulfuric acid solution, to obtain a cross section of the molded article. Finally, the depth of the erosion formed on the cross section of the molded article (unit: mm) was measured. A erosion depth of 1.2 mm or less was considered excellent.

[0074] <Flame Retardancy Test> In order to measure the flame retardancy of the thermoplastic polyester elastomer resin compositions of each of the Examples and Comparative Examples, a flammability test was carried out as follows.

[0075] First, an injection-molded article measuring 125 mm in length, 13 mm in width, and 1.6 mm in thickness was obtained from the thermoplastic polyester elastomer resin composition. Next, the maximum burning time was measured using a test method based on the UL94V test. A burning time of 30 seconds or less was evaluated as having excellent flame retardancy.

[0076] <Heat Aging Resistance Test 1 (Measurement of Elongation at Break after Heat Treatment)> In order to evaluate the heat aging resistance of the thermoplastic polyester elastomer resin compositions of each Example and Comparative Example, the following elongation at break measurement test was carried out.

[0077] (Preparation of Test Pieces) First, an injection-molded article having a length of 100 mm, a width of 100 mm, and a thickness of 2.0 mm was obtained by injecting a thermoplastic polyester elastomer resin composition from an injection molding machine with a cylinder temperature set to 20° C. higher than the melting point of the resin composition and a mold temperature set to 30° C. Next, a JIS No. 3 dumbbell shape was punched out of the injection-molded article along the flow direction to prepare a test piece.

[0078] (Dry heat treatment and measurement of elongation at break) The test piece was treated in a gear-type hot air dryer at 175°C for 240 hours. Thereafter, the absolute tensile elongation (elongation at break) of the test piece was measured in accordance with JIS K6251:2010.

[0079] <Heat Aging Resistance Test 2 (Checking for Cracks by Winding Test After Heat Treatment)> In order to evaluate the heat aging resistance of the thermoplastic polyester elastomer resin compositions of each Example and Comparative Example, a winding test was carried out after the following heat treatment to check for cracks.

[0080] (Preparation of Test Pieces) Test pieces (JIS No. 3 dumbbell shape) of the thermoplastic polyester elastomer resin composition were prepared in the same manner as in the heat aging resistance test 1 above.

[0081] (Dry heat treatment, winding test) The test piece was treated at 175°C for 240 hours in a gear-type hot air dryer. After the test piece was sufficiently cooled, it was further cooled at -25°C for 5 hours or more, and then wound around a mandrel while still cooled, and the cross section of the test piece was observed for cracks. The observation results were evaluated according to the following criteria: A: No cracks were observed. B: Cracks were observed after the dry heat treatment or winding test.

[0082] <Copper Damage Resistance Test 1 (Measurement of Elongation at Break after Heat Treatment)> In order to evaluate the copper damage resistance of the thermoplastic polyester elastomer resin compositions of each Example and Comparative Example, the following elongation at break test was carried out.

[0083] (Preparation of Test Pieces) First, an injection-molded article having a length of 100 mm, a width of 100 mm, and a thickness of 2.0 mm was obtained by injecting a thermoplastic polyester elastomer resin composition from an injection molding machine with a cylinder temperature set to 20° C. higher than the melting point of the resin composition and a mold temperature set to 30° C. Next, a JIS No. 3 dumbbell shape was punched out of the injection-molded article along the flow direction to prepare a test piece.

[0084] (Dry heat treatment and measurement of elongation at break) The above test specimen was placed on one side of a copper plate and treated in a gear-type hot air dryer at 175°C for 240 hours. Thereafter, the absolute tensile elongation (elongation at break) of the test specimen was measured in accordance with JIS K6251:2010.

[0085] <Copper Damage Resistance Test 2 (Checking for Cracks by Winding Test After Heat Treatment)> In order to evaluate the copper damage resistance of the thermoplastic polyester elastomer resin compositions of each Example and Comparative Example, a winding test was carried out after the following heat treatment to check for cracks.

[0086] (Preparation of Test Pieces) Test pieces (JIS No. 3 dumbbell shape) of the thermoplastic polyester elastomer compositions were prepared in the same manner as in the copper damage resistance test 1 above.

[0087] (Dry heat treatment, winding test) The above test piece was placed on one side of a copper plate and treated in a gear-type hot air dryer at 175°C for 240 hours. The test piece was then sufficiently cooled, and then further cooled at -25°C for 5 hours or more. In the cooled state, the test piece was wound around a mandrel and observed for the occurrence of cracks on the cross section of the test piece. The observation results were evaluated according to the following criteria: A: No cracks occurred. B: Cracks occurred after the dry heat treatment or winding test.

[0088] <Extrusion moldability> The pellets melt-kneaded in the twin-screw extruder were extruded again through a T-die in a single-screw extruder to produce a 0.2 mm thick sheet. The smoothness of the extrusion molded product was evaluated based on the appearance of the sheet using the following criteria: A: No roughness or foaming occurs, and the sheet appearance and surface smoothness are good. B: No sheet irregularities (melt fracture) or foaming occurs, but a uniform roughness similar to that of a grained finish is present. C: Some sheet irregularities (melt fracture), foaming, and poor dispersion of the flame retardant occur.

[0089] <Melting Point (Tm) and Melting Point Difference (Tm1-Tm3)> The melting point (Tm) of the thermoplastic polyester elastomer (A) in each example and comparative example was determined by the following method. That is, the thermoplastic polyester elastomer (A) was dried under reduced pressure at 50°C for 15 hours and measured using a differential scanning calorimeter DSC-50 (Shimadzu Corporation) at a temperature increase rate of 20°C / min from room temperature, and the temperature at the peak of the endothermic heat due to melting was determined as the melting point (Tm) of the thermoplastic polyester elastomer (A). Here, a sample for measuring the melting point of the thermoplastic polyester elastomer (A) was prepared by weighing 10 mg into an aluminum pan (TA Instruments, product number 900793.901) and sealing it with an aluminum lid (TA Instruments, product number 900794.901). The melting point measurement was also performed under an argon atmosphere.

[0090] Furthermore, the melting point difference (Tm1-Tm3) of the thermoplastic polyester elastomer (A) was determined by the following method. First, 10 mg of the thermoplastic polyester elastomer (A) was dried under reduced pressure at 50°C for 15 hours and weighed into an aluminum pan (manufactured by TA Instruments, product number 900793.901). The pan was then sealed with an aluminum lid (manufactured by TA Instruments, product number 900794.901) to prepare a measurement sample. Next, the aluminum pan containing the sealed measurement sample was heated from room temperature to 300°C at a heating rate of 20°C / min under a nitrogen atmosphere using a differential scanning calorimeter DSC-50 (manufactured by Shimadzu Corporation), and held at 300°C for 3 minutes. Thereafter, the aluminum pan was immersed in liquid nitrogen for rapid cooling, and the temperature was lowered to room temperature at a cooling rate of 100°C / min. After leaving it at room temperature for 30 minutes, the temperature was again raised from room temperature to 300°C at a heating rate of 20°C / min using a differential scanning calorimeter DSC-50 (Shimadzu Corporation). This cycle was repeated three times, and the melting point difference (Tm1-Tm3) was calculated from the melting point (Tm1) measured when the temperature was lowered to room temperature the first time and the melting point (Tm3) measured when the temperature was lowered to room temperature the third time.

[0091] <Reduced Viscosity> 0.05 g of the resin was dissolved in 25 mL of a mixed solvent (phenol / tetrachloroethane=60 / 40 (mass ratio)), and the reduced viscosity was measured at 30° C. using an Ostwald viscometer.

[0092] The terminal carboxyl group concentration (equivalents / 1×10 g) of the thermoplastic polyester elastomer (A) was measured by dissolving 200 mg of a thoroughly dried sample (polyester elastomer) in 10 mL of hot benzyl alcohol, cooling the resulting solution, adding 10 mL of chloroform and phenol red, and titrating with a 1 / 25 N potassium hydroxide solution (a solution of KOH in methanol) to determine the acid value (equivalents / 1×10 g), which was used as the terminal carboxyl group concentration (equivalents / 1×10 g). 0.05 g of the resin was dissolved in 25 mL of a mixed solvent (phenol / tetrachloroethane = 60 / 40 (mass ratio)) and measured at 30°C using an Ostwald viscometer.

[0093] <Raw materials used in the examples and comparative examples> The following raw materials were used in the examples and comparative examples.

[0094] <Thermoplastic Polyester Elastomer (A) and Comparative Resins> (Thermoplastic Polyester Elastomer (A-1)) 100 parts by mass of an aliphatic polycarbonate diol (carbonate diol UH-CARB 200, molecular weight 2000, 1,6-hexanediol type, manufactured by Ube Industries, Ltd.) and 8.6 parts by mass of diphenyl carbonate were charged and reacted at a temperature of 205°C and 130 Pa. After 2 hours, the contents were cooled to obtain an aliphatic polycarbonate diol (number average molecular weight 10,000). 43 parts by mass of this aliphatic polycarbonate diol (PCD) and 57 parts by mass of polybutylene terephthalate (PBT) having a number average molecular weight of 30,000 were stirred at 230°C to 245°C under 130 Pa for 1 hour. After confirming that the resin had become transparent, the contents were removed and cooled to obtain thermoplastic polyester elastomer (A-1). The melting point of this thermoplastic polyester elastomer (A-1) was 207°C, the melting point difference (Tm1-Tm3) was 25°C, the reduced viscosity was 1.21 dl / g, and the terminal acid value was 44 eq / ton. The composition and physical properties of the thermoplastic polyester elastomer (A-1) are shown in Table 1.

[0095] (Thermoplastic Polyester Elastomer (A-2)) 100 parts by mass of an aliphatic polycarbonate diol (carbonate diol UH-CARB 200 manufactured by Ube Industries, Ltd., molecular weight 2000, 1,6-hexanediol type) and 8.6 parts by mass of diphenyl carbonate were charged and reacted at a temperature of 205°C and 130 Pa. After 1 hour, the contents were cooled to obtain an aliphatic polycarbonate diol (number average molecular weight 5000). 43 parts by mass of this aliphatic polycarbonate diol (PCD) and 57 parts by mass of polybutylene terephthalate (PBT) having a number average molecular weight of 30,000 were stirred at 230°C to 245°C under 130 Pa for 1 hour, and after confirming that the resin had become transparent, the contents were removed. The removed pellets were heated at 170 to 180°C to carry out solid-state polycondensation, yielding a thermoplastic polyester elastomer (A-2). The melting point of this thermoplastic polyester elastomer (A-2) was 208°C, the melting point difference (Tm1 - Tm3) was 15°C, the reduced viscosity was 1.21 dl / g, and the terminal acid value was 7 eq / ton. The composition and physical properties of the thermoplastic polyester elastomer (A-2) are shown in Table 1.

[0096] (Thermoplastic Polyester Elastomer (A-3)) 100 parts by mass of an aliphatic polycarbonate diol (carbonate diol UH-CARB 200 manufactured by Ube Industries, Ltd., molecular weight 2000, 1,6-hexanediol type) and 8.6 parts by mass of diphenyl carbonate were charged and reacted at a temperature of 205°C and 130 Pa. After 2 hours, the contents were cooled to obtain an aliphatic polycarbonate diol (number average molecular weight 10,000). 30 parts by mass of this aliphatic polycarbonate diol (PCD) and 70 parts by mass of polybutylene terephthalate (PBT) having a number average molecular weight of 30,000 were stirred at 230°C to 245°C under 130 Pa for 1 hour, and after confirming that the resin had become transparent, the contents were removed and cooled to obtain thermoplastic polyester elastomer (A-3). The melting point of this thermoplastic polyester elastomer (A-3) was 212°C, the melting point difference (Tm1 - Tm3) was 18°C, the reduced viscosity was 1.20 dl / g, and the terminal acid value was 41 eq / ton. The composition and physical properties of the thermoplastic polyester elastomer (A-3) are shown in Table 1.

[0097] (Thermoplastic polyester elastomer (A-4)) Using the same method as above, a thermoplastic polyester elastomer (A-4) was obtained using terephthalic acid, 1,4-butanediol, and polyoxytetramethylene glycol (PTMG; number average molecular weight 1000) as constituent components, with a hard segment (polybutylene terephthalate) / soft segment (PTMG) ratio of 64 / 36 (mass %). The melting point of this thermoplastic polyester elastomer (A-4) was 203°C, the reduced viscosity was 1.75 dl / g, and the terminal acid value was 50 eq / ton. The composition and physical properties of the thermoplastic polyester elastomer (A-4) are shown in Table 1. Note that the thermoplastic polyester elastomer (A-4) is a polyether-type polyester elastomer for comparative examples, and does not contain an aliphatic polycarbonate as a soft segment.

[0098] (Polyester (A-5)) The following commercially available compound was prepared as polyester (A-5). Polybutylene terephthalate (PBT): 1100-211XG, manufactured by Changchun Group Co., Ltd. The MFR (235°C, 2.16 kg) of this PBT was 4 to 9 g / 10 min, melting point 223°C, reduced viscosity 1.23 to 1.30 dl / g, and terminal acid value 33 to 40 eq / ton. The composition and physical properties of polyester (A-5) are shown in Table 1.

[0099]

[0100] <Olefin-Based Elastomer (B)> The following commercially available compounds were prepared as the olefin-based elastomer (B). (B-1) Styrene-isobutylene-styrene block copolymer: SIBSTAR 062T, manufactured by Kaneka Corporation, styrene / isobutylene ratio = 23 / 77 (mass ratio), MFR (230 ° C, 2.16 kg) = 10 g / 10 min (B-2) Styrene-isobutylene-styrene block copolymer: SIBSTAR 073T, manufactured by Kaneka Corporation, styrene / isobutylene ratio = 30 / 70 (mass ratio), MFR (230 ° C, 2.16 kg) = 6 g / 10 min (B-3) Styrene-isobutylene-styrene block copolymer: SIBSTAR 102T, manufactured by Kaneka Corporation, styrene / isobutylene ratio = 15 / 85 (mass ratio), MFR (230 ° C, 2.16 kg) = 0.6 g / 10 min (B-4) Styrene-isobutylene-styrene block copolymer: SIBSTAR 103T, manufactured by Kaneka Corporation, styrene / isobutylene ratio = 30 / 70 (mass ratio), MFR (230°C, 2.16 kg) = 0.1 g / 10 min. (B-5) Styrene-ethylene-butylene-styrene block copolymer: Tuftec H1052, manufactured by Asahi Kasei Corporation, styrene / ethylene-butylene ratio = 20 / 80 (mass ratio), MFR (230°C, 2.16 kg) = 13 g / 10 min. Note that (B-5) is an olefin-based elastomer for comparison containing a conjugated diene as a monomer component. In other words, it is an olefin-based elastomer containing butadiene as a monomer component and hydrogenated after polymerization.

[0101] <Acid End-Capping Agent (C)> The following commercially available compounds were prepared as the acid end-capping agent (C): (C-1) Alicyclic polycarbodiimide: Carbodilite HMV-15CA, manufactured by Nisshinbo Chemical Inc. (C-2) Bisphenol F-type diepoxy compound: Epicron 830, manufactured by DIC Corporation

[0102] <Flame Retardant (D)> The following commercially available compounds were prepared as flame retardant (D): (D-1) Polybrominated styrene (polydibromostyrene): PDBS-80, Chemtura Japan, bromine content = 59%, melting point = none (amorphous) (D-2) Bis(pentabromophenyl)ethane: SAYTEX 8010, Albemarle, bromine content = 82%, melting point = 350°C (D-3) Ethylene bistetrabromophthalimide: SYTEX BT-93, Albemarle, bromine content = 67%, melting point = 456°C

[0103] <Flame Retardant Synergist (E)> Antimony trioxide (manufactured by Twinkling Star) was used as the flame retardant synergist (E).

[0104] Preparation of Thermoplastic Polyester Elastomer Resin Compositions of Examples 1 to 15 and Comparative Examples 1 to 8 The thermoplastic polyester elastomer (A), olefin-based elastomer (B), acid end-capping agent (C), and flame retardant (D) were charged into a twin-screw extruder set at a cylinder temperature of 180 to 230°C in the combinations and ratios (parts by mass) shown in Tables 2 and 3, and kneaded in the twin-screw extruder to obtain pellets of the thermoplastic polyester elastomer resin compositions of Examples 1 to 15 and Comparative Examples 1 to 8, respectively. The resulting pellets were used to perform the various evaluations described above. The results are shown in Tables 2 and 3.

[0105]

[0106]

[0107] <Discussion> Table 2 shows that all of the thermoplastic polyester elastomer resin compositions of Examples 1 to 15 possess excellent acid resistance, flame retardancy, flexibility (surface hardness), heat aging resistance, and copper damage resistance. Furthermore, a comparison of Examples 1 and 2 reveals that as the amount of olefinic elastomer (B) added increases, acid resistance and flexibility improve, but the maximum burning time increases and flame retardancy decreases. A comparison of Examples 2 to 5 reveals that there is no difference in flame retardancy despite the type of olefinic elastomer (B). A comparison of Example 2 and Example 5 reveals that in Example 5, the low MFR (high viscosity) of the olefinic elastomer (B-4) makes it less susceptible to shear during extrusion, resulting in spherical domains, which reduces the effective surface area and bypass effect, resulting in lower acid resistance compared to Example 2. A comparison between Examples 4 and 5 reveals that, although the olefinic elastomer (B-4) has a lower MFR (high viscosity) than the olefinic elastomer (B-3), its high styrene content increases its compatibility with the thermoplastic polyester elastomer (A) and improves extrusion moldability. A comparison between Examples 2 and 5 reveals that, in Example 2, which uses an olefinic polymer (B-1) with a high MFR (low viscosity), heat aging resistance and copper damage resistance are reduced, but the olefinic polymer is stretched rather than spherical, resulting in improved acid resistance due to the bypass effect and improved extrusion moldability due to surface smoothing. A comparison between Examples 6 to 9 reveals that, in the case of a composition containing a flame retardant (D) and a flame retardant coagent (E), increasing the amount of flame retardant (D) shortens the maximum burning time and improves flame retardancy. Furthermore, increasing the amount of flame retardant relatively reduces the content of thermoplastic polyester elastomer (A), thereby improving acid resistance. From a comparison of Examples 4, 10, and 11, it can be seen that Example 11, which used the thermoplastic polyester elastomer (A-2) having a low terminal acid value, can exhibit high heat aging resistance at the same level as Examples 4 and 10, which added the acid terminal blocking agent (C), even without adding the acid terminal blocking agent (C).Furthermore, a comparison between Examples 10 and 13 indicates that no problems are observed in heat aging resistance, regardless of whether the acid end-capping agent (C) is an epoxy compound (Example 13) or a carbodiimide compound (Example 10). A comparison between Examples 10 and 12 indicates that an increase in the hard segment content of the thermoplastic polyester elastomer (A) reduces flexibility and heat aging resistance, but further improves acid resistance.

[0108] On the other hand, according to Table 3, the thermoplastic polyester elastomer resin compositions of Comparative Examples 1 to 8 were inferior to those of the Examples in at least one of acid resistance, flame retardancy, flexibility, heat aging resistance, copper damage resistance, and extrusion moldability. Specifically, Comparative Example 1, which did not contain the olefin polymer (B), was significantly inferior in acid resistance and flexibility. Comparative Example 2 had poor flame retardancy due to the increased amount of olefin elastomer (B) added, resulting in a longer maximum burning time. Comparative Examples 3 and 4 did not contain the flame retardant (D) or the flame retardant aid (E) or contained an insufficient amount of flame retardant (D), resulting in a longer maximum burning time and significantly poorer flame retardancy. Comparative Example 5 had an excessive amount of flame retardant (D), resulting in a significant decrease in elongation and poor heat aging resistance and copper damage resistance. Comparative Example 6 had poor acid resistance and heat aging resistance due to the soft segment of the thermoplastic polyester elastomer (A-4) being polyether. Comparative Example 7 was inferior in heat aging resistance and copper damage resistance because the olefin polymer (B-5) contained residual double bonds (unsaturated bonds).Comparative Example 8 was significantly inferior in flexibility, heat aging resistance, and copper damage resistance because the polyester resin (A-5) was used instead of the thermoplastic polyester elastomer (A).

[0109] The thermoplastic polyester elastomer resin composition of the present invention has excellent acid resistance, flame retardancy, heat aging resistance, copper damage resistance, and flexibility, and is therefore extremely useful as an automotive part, particularly as a coating material for in-vehicle cables, and as various other parts.

Claims

1. A thermoplastic polyester elastomer resin composition containing a thermoplastic polyester elastomer (A) and an olefin-based elastomer (B), wherein the thermoplastic polyester elastomer (A) is formed by bonding hard segments and soft segments, the hard segments are composed of a polyester having an aromatic dicarboxylic acid and an aliphatic or alicyclic diol as constituent components, the soft segments contain an aliphatic polycarbonate, the olefin-based elastomer (B) contains an aromatic vinyl polymer block and an alkene having 3 to 20 carbon atoms as monomer components, and does not contain a conjugated diene as a monomer component, and the content of the thermoplastic polyester elastomer (A) is 50 to 90 mass% and the content of the olefin-based elastomer (B) is 10 to 50 mass% based on the total amount of the thermoplastic polyester elastomer (A) and the olefin-based elastomer (B). The thermoplastic polyester elastomer resin composition contains 0 to 5 parts by mass of an acid end-capping agent (C) and 7 to 33 parts by mass of a flame retardant (D) relative to 100 parts by mass in total of the thermoplastic polyester elastomer (A) and the olefin-based elastomer (B).

2. The thermoplastic resin composition according to claim 1, wherein the flame retardant (D) is a brominated flame retardant.

3. The thermoplastic polyester elastomer resin composition according to claim 1, wherein the olefin elastomer (B) comprises a copolymer of an aromatic vinyl polymer block and isobutene.

4. The thermoplastic polyester elastomer resin composition according to claim 1, wherein the flame retardant (D) is an amorphous brominated flame retardant or a brominated flame retardant having a melting point of 270°C or less.

5. The thermoplastic polyester elastomer resin composition according to claim 1, wherein the corrosion depth of the thermoplastic polyester elastomer resin composition measured in accordance with an acid resistance test method is 1.2 mm or less.

6. The thermoplastic polyester elastomer resin composition according to claim 1, wherein the elongation at break of said thermoplastic polyester elastomer resin composition measured in accordance with the heat aging resistance test method is 100% or more.

7. A thermoplastic polyester elastomer resin composition according to claim 1, wherein the elongation at break of said thermoplastic polyester elastomer resin composition measured in accordance with the copper damage resistance test method is 100% or more.

8. The thermoplastic polyester elastomer resin composition according to claim 1, wherein the hardness of the thermoplastic polyester elastomer resin composition measured in accordance with the hardness testing method for thermoplastics specified in ASTM D 2240 is D30 to D50.

9. The thermoplastic polyester elastomer resin composition according to claim 1, wherein the thermoplastic polyester elastomer (A) has a melting point of 150 to 225°C, and wherein the difference in melting points (Tm1 - Tm3) between the melting point of the thermoplastic polyester elastomer (A) measured at the first temperature decrease in a procedure in which the thermoplastic polyester elastomer (A) is heated from room temperature to 300°C at a heating rate of 20°C / min using a differential scanning calorimeter, maintained at 300°C for 3 minutes, and then cooled to room temperature at a heating rate of 100°C / min, is repeated three times, and the melting point (Tm1) of the thermoplastic polyester elastomer (A) measured at the third temperature decrease in the procedure is 0 to 50°C.

10. A thermoplastic polyester elastomer resin composition according to claim 1, wherein the content of terephthalic acid and / or naphthalenedicarboxylic acid in all dicarboxylic acids constituting the polyester of the hard segment is 70 mol % or more.

11. The thermoplastic polyester elastomer resin composition according to claim 1, wherein the terminal acid value of the thermoplastic polyester elastomer (A) is 60 eq / ton or less.

12. The thermoplastic polyester elastomer resin composition according to claim 1, wherein the reduced viscosity of the thermoplastic polyester elastomer (A) is 0.5 to 4.0 dl / g.

13. The thermoplastic polyester elastomer resin composition according to claim 1, further comprising a flame retardant aid.

14. The thermoplastic polyester elastomer resin composition according to claim 13, wherein the flame retardant aid is an antimony oxide compound.

15. The thermoplastic polyester elastomer resin composition according to any one of claims 1 to 14, which is for extrusion molding.

16. The thermoplastic polyester elastomer resin composition according to any one of claims 1 to 14, which is used for cable coating.

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