Polyester elastomer resin composition and cable covering material made therefrom

Abstract

The present invention is a polyester elastomer resin composition that has superior strong acid resistance and thermal aging resistance and is suitable for extrusion molding, said polyester elastomer resin composition including: 50-90 parts by mass of a polyester elastomer (A) that is obtained by bonding a hard segment, which comprises a polyester having an aromatic dicarboxylic acid and an aliphatic and / or alicyclic diol as structural components thereof, and at least one type of soft segment selected from an aliphatic polyester and an aliphatic polycarbonate; 10-50 parts by mass of an unmodified olefinic elastomer (B); and furthermore, 0-5 parts by mass of an acid end capping agent (C) per total 100 parts by mass of the polyester elastomer (A) and the unmodified olefinic elastomer (B), wherein the carboxyl group concentration in the polyester elastomer resin composition is 10 eq / ton or less.

Description

Technical Field

[0001] The present invention relates to a polyester elastomer composition suitable for extrusion molding, which is excellent in acid resistance and heat aging resistance.

Background Art

[0002] As thermoplastic polyester elastomers, crystalline polyesters such as polybutylene terephthalate (PBT) and polybutylene naphthalate (PBN) have long been used as hard segments, and polyoxyalkylene glycols such as polytetramethylene glycol (PTMG) and / or aliphatic polyesters such as polycaprolactone (PCL) and polybutylene adipate (PBA) are used as soft segments. Such materials are known and have been put into practical use.

[0003] However, although polyester polyether type elastomers using polyoxyalkylene glycols as soft segments are excellent in water resistance and low temperature characteristics, they are inferior in heat aging resistance. Also, polyester polyester type elastomers using aliphatic polyesters as soft segments are known to be excellent in heat aging resistance, although their water resistance and low temperature characteristics are slightly inferior.

[0004] For the purpose of solving the above-mentioned drawbacks, polyester polycarbonate type elastomers using polycarbonate as a soft segment have been proposed (see, for example, Patent Documents 1 to 5).

[0005] As a result, the above problems are solved, and the polyester polycarbonate type elastomers disclosed in these patent documents utilize their excellent characteristics and are used in applications that require high heat aging resistance, such as members around the engine of automobiles.

[0006] In the future of the automotive industry, electric vehicles are expected to become the mainstream, replacing conventional gasoline-powered vehicles. This will lead to an increase in the number of in-vehicle cables, and the aforementioned polyester polycarbonate elastomer is expected to be a promising material for next-generation in-vehicle cable sheathing due to its high heat aging resistance and flexibility. However, a crucial requirement for this application is passing a battery fluid (sulfuric acid) drop test, and conventional polyester elastomers have not been able to achieve this. There was a need to improve acid resistance while maintaining high heat aging resistance and flexibility. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Special Publication No. 7-39480 [Patent Document 2] Japanese Patent Application Publication No. 10-182782 [Patent Document 3] Japanese Patent Publication No. 2001-206939 [Patent Document 4] Japanese Patent Publication No. 2001-240663 [Patent Document 5] Patent No. 4244067 [Overview of the project] [Problems that the invention aims to solve]

[0008] This invention was conceived in view of the current state of the prior art, and its objective is to provide a polyester elastomer composition suitable for extrusion molding, which has excellent acid resistance and heat aging resistance. In particular, it aims to provide a polyester elastomer composition suitable for cable covering materials manufactured by extrusion molding. [Means for solving the problem]

[0009] In order to achieve the above objective, the inventors diligently studied polyester elastomer compositions with excellent acid resistance and heat aging resistance, and as a result, finally completed the present invention.

[0010] In other words, the present invention is as follows: [1] A polyester elastomer resin composition comprising 50 to 90 parts by mass of a polyester elastomer (A) comprising a hard segment made of a polyester composed of an aromatic dicarboxylic acid and an aliphatic and / or alicyclic diol, and at least one soft segment selected from aliphatic polyester and aliphatic polycarbonate, 10 to 50 parts by mass of an unmodified olefin-based elastomer (B), and further comprising 0.1 to 5 parts by mass of an acid end-capping agent (C) per 100 parts by mass of the total of the polyester elastomer (A) and the unmodified olefin-based elastomer (B), wherein the carboxyl group concentration in the resin composition is 10 eq / ton or less. The features include: the erosion depth in the acid resistance test is 1.2 mm or less; the heat resistance elongation half-life at 170°C is 500 hours or more; and the hard segment of the polyester elastomer (A) does not contain isophthalic acid as a constituent component. Polyester elastomer resin composition. [2] The polyester elastomer resin composition according to [1], further containing 1 to 10 parts by mass of epoxy group-containing polyolefin (D) per 100 parts by mass of polyester elastomer (A) and unmodified olefin-based elastomer (B). [3] The unmodified olefin elastomer (B) is an elastomer containing styrene as a copolymer component. 、 The polyester elastomer resin composition described in [1] or [2]. [4] The polyester elastomer (A) is a copolymer having a melting point of 150 to 230°C, with terephthalic acid, 1,4-butanediol, and aliphatic polycarbonate diol as the main components. 、 A polyester elastomer resin composition according to any one of [1] to [3]. [5] A polyester elastomer resin composition according to any one of [1] to [4], further containing 5 to 30 parts by mass of a brominated flame retardant (E) and a flame retardant aid (F) with respect to 100 parts by mass of a total of polyester elastomer (A) and unmodified olefin elastomer (B). [6] A polyester elastomer resin composition according to any one of [1] to [4], further containing 5 to 50 parts by mass of a phosphorus-based flame retardant (G) per 100 parts by mass of a total of polyester elastomer (A) and unmodified olefin-based elastomer (B). [7] The polyester elastomer resin composition according to [6], wherein the phosphorus-based flame retardant (G) has an average particle size D50 of 20 μm or less and a phosphorus concentration of 15% by mass or more. [8] For cable sheathing. 、 A polyester elastomer resin composition according to any one of [1] to [7]. [9] A cable covering material comprising the polyester elastomer resin composition described in any of [1] to [7]. [Effects of the Invention]

[0011] The polyester elastomer resin composition of the present invention exhibits excellent acid resistance and heat aging resistance, while also possessing good outer diameter stability and surface smoothness even in extrusion molding. [Modes for carrying out the invention]

[0012] [Polyester elastomer (A)] The polyester elastomer (A) used in the present invention consists of a hard segment and a soft segment. The hard segment is made of polyester. The aromatic dicarboxylic acid constituting the polyester of the hard segment is not particularly limited, and a wide range of ordinary aromatic dicarboxylic acids are used, but it is desirable that the main aromatic dicarboxylic acid be terephthalic acid or naphthalenedicarboxylic acid (among the isomers, 2,6-naphthalenedicarboxylic acid is preferred). Of the total dicarboxylic acids constituting the polyester of the hard segment, terephthalic acid or naphthalenedicarboxylic acid is preferably 70 mol% or more, and more preferably 80 mol% or more. Other dicarboxylic acid components include aromatic dicarboxylic acids such as diphenyl dicarboxylic acid, isophthalic acid, and 5-sodium sulfisoisophthalic acid; alicyclic dicarboxylic acids such as cyclohexane dicarboxylic acid and tetrahydrophthalic anhydride; and aliphatic dicarboxylic acids such as succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, dimer acid, and hydrogenated dimer acid. These are used within a range that does not significantly lower the melting point of the polyester elastomer (A), and their amount is preferably 30 mol% or less of the total acid component, and more preferably 20 mol% or less.

[0013] Furthermore, in the polyester elastomer (A) used in the present invention, the aliphatic or alicyclic diol constituting the polyester of the hard segment is not particularly limited, and a wide range of general aliphatic or alicyclic diols are widely used, but it is desirable that it be mainly alkylene glycols having 2 to 8 carbon atoms. Specifically, examples include ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol, and 1,4-cyclohexanedimethanol. Among these, ethylene glycol or 1,4-butanediol is preferred for imparting heat resistance.

[0014] As components constituting the polyester of the above hard segment, those composed of butylene terephthalate units (units composed of terephthalic acid and 1,4-butanediol) or butylene naphthalate units (units composed of 2,6-naphthalenedicarboxylic acid and 1,4-butanediol) are preferable from the viewpoints of physical properties, moldability, and cost performance.

[0015] Further, when a suitable aromatic polyester as the polyester constituting the hard segment in the polyester elastomer (A) used in the present invention is produced in advance and then copolymerized with the soft segment component, the aromatic polyester can be easily obtained according to the usual polyester production method. Further, it is desirable that such a polyester has a number average molecular weight of 10,000 to 40,000.

[0016] The soft segment of the polyester elastomer (A) used in the present invention is at least one selected from aliphatic polyesters and aliphatic polycarbonates.

[0017] Examples of the aliphatic polyester include poly(ε-caprolactone), polyenanthlactone, polycaprylolactone, polybutylene adipate, and the like. Among these, poly(ε-caprolactone) and polybutylene adipate are preferable from the viewpoint of elastic properties.

[0018] The aliphatic polycarbonate preferably mainly consists of aliphatic diol residues having 2 to 12 carbon atoms. Examples of these aliphatic diols include 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, 2 - methyl - 1,8 - octanediol, and the like. Particularly, aliphatic diols having 5 to 12 carbon atoms are preferred in terms of the flexibility and low - temperature properties of the resulting polyester elastomer. These components may be used alone or, if necessary, two or more of them may be used in combination based on the examples described below.

[0019] As the aliphatic polycarbonate diol having good low - temperature properties and constituting the soft segment of the polyester elastomer (A) in the present invention, those having a low melting point (for example, 70°C or lower) and a low glass transition temperature are preferred. Generally, the aliphatic polycarbonate diol composed of 1,6 - hexanediol used to form the soft segment of the polyester elastomer has a low glass transition temperature of around - 60°C and a melting point of around 50°C, so it has good low - temperature properties. In addition, for example, the aliphatic polycarbonate diol obtained by copolymerizing an appropriate amount of 3 - methyl - 1,5 - pentanediol with the above - mentioned aliphatic polycarbonate diol has a slightly higher glass transition point than the original aliphatic polycarbonate diol, but its melting point decreases or becomes amorphous, so it corresponds to an aliphatic polycarbonate diol having good low - temperature properties. Also, for example, the aliphatic polycarbonate diol composed of 1,9 - nonanediol and 2 - methyl - 1,8 - octanediol has a melting point of about 30°C and a glass transition temperature of around - 70°C, which is sufficiently low, so it corresponds to an aliphatic polycarbonate diol having good low - temperature properties.

[0020] As the soft segment of polyester elastomer (A), aliphatic polycarbonate diols are preferred from the viewpoint of heat aging resistance of the polyester elastomer resin composition. In particular, copolymers having a melting point of 150 to 230°C, mainly composed of terephthalic acid, 1,4-butanediol, and aliphatic polycarbonate diols, are preferred. At this time, it is preferable that terephthalic acid accounts for 70 mol% or more of the total dicarboxylic acid components constituting polyester elastomer (A), and that the total of 1,4-butanediol and aliphatic polycarbonate diol accounts for 70 mol% or more of the total diol components. The melting point of polyester elastomer (A) is more preferably 190 to 220°C, and even more preferably 200 to 218°C.

[0021] In the polyester elastomer (A) used in the present invention, the mass ratio of hard segments to soft segments is generally preferably 30:70 to 95:5, more preferably 40:60 to 90:10, even more preferably 45:55 to 90:10, particularly preferably 50:50 to 90:10, and most preferably in the range of 60:40 to 80:20.

[0022] Generally, in thermoplastic polyester elastomers, the higher the ratio of hard segments, the better the heat aging resistance and acid resistance. However, a high ratio of hard segments is synonymous with high material hardness, and if the material hardness is too high, the flexibility and low-temperature properties, which are important characteristics of elastomers, will be impaired. Therefore, the mass ratio of hard segments to soft segments in polyester elastomers is preferably within the range mentioned above.

[0023] The polyester elastomer (A) used in the present invention has hard segments and soft segments bonded together. Here, "bonded" means that the hard segments and soft segments are not bonded together by a chain extender such as an isocyanate compound, but rather the units constituting the hard segments and soft segments are directly bonded together by ester bonds or carbonate bonds. For example, it is preferable to obtain the polyester constituting the hard segments and the polycarbonate constituting the soft segments by repeatedly performing transesterification and depolymerization reactions in a molten state for a certain period of time.

[0024] The polyester elastomer (A) used in the present invention can be produced by known methods. For example, a method in which a lower alcohol diester of a dicarboxylic acid, an excess amount of low molecular weight glycol, and a soft segment component are transesterified in the presence of a catalyst, and the resulting reaction product is polycondensed; or a method in which a dicarboxylic acid, an excess amount of glycol, and a soft segment component are esterified in the presence of a catalyst, and the resulting reaction product is polycondensed; or a method in which a hard segment polyester is prepared in advance, and a soft segment component is added to it and randomized by a transesterification reaction; or a method in which hard segments and soft segments are linked with a chain linker; and if poly(ε-caprolactone) is used as the soft segment, an addition reaction of ε-caprolactone monomer to the hard segment may be carried out. Any of these methods may be used.

[0025] If the polyester elastomer (A) used in the present invention is a polyester elastomer mainly composed of terephthalic acid, 1,4-butanediol, and aliphatic polycarbonate diol, its production can be carried out using the method described in Japanese Patent No. 4244067 (Patent Document 5 above). The polyester elastomer (A) produced by this method has the characteristic that the difference in melting points (Tm1-Tm3) between the melting point (Tm1) obtained in the first measurement and the melting point (Tm3) obtained in the third measurement is 0 to 50°C when the cycle of heating from room temperature to 300°C at a heating rate of 20°C / min using a differential scanning calorimeter, holding at 300°C for 3 minutes, and then cooling down to room temperature at a cooling rate of 100°C / min is repeated three times.

[0026] [Unmodified olefin-based elastomer (B)] In the present invention, the unmodified olefin-based elastomer (B) refers to a block copolymer containing an olefin compound as a constituent component. Here, the olefin compounds are ethylene, propylene, 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, and 3-methyl-1-pentene. Examples include α-olefins such as tetraphosphate, 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, and 12-ethyl-1-tetradecene, as well as conjugated dienes such as butadiene and isoprene. In addition to olefin compounds, the olefin-based elastomer may also contain vinyl aromatic monomers such as styrene, methylstyrene, dimethylstyrene, and ethylstyrene, vinyl cyanide monomers such as acrylonitrile, and (meth)acrylic acid ester monomers such as methyl acrylate, ethyl acrylate, methyl methacrylate, and ethyl methacrylate as constituent components. Here, "unmodified" means that the olefin-based elastomer obtained from the above components has not been modified with compounds containing functional groups such as carboxyl groups, hydroxyl groups that react with the terminal functional groups of polyester elastomer (A), acid anhydride groups, epoxy groups, hydroxyl groups, carbodiimide groups, oxazoline groups, etc., that is, it has not been copolymerized with compounds containing the aforementioned functional groups. Hydrogenation of the double bonds remaining in the olefin-based elastomer is not included in the modification. Hereinafter, "unmodified olefin-based elastomer (B)" may also be referred to as "olefin-based elastomer (B)".

[0027] Furthermore, the unmodified olefin elastomer (B) used in the present invention is more preferably an elastomer containing styrene as a copolymer component, a so-called styrene elastomer. A styrene elastomer is a hydrogenated styrene-conjugated diene block copolymer (hydrogenated styrene-diene block copolymer). A styrene-conjugated diene block copolymer is a block copolymer consisting of a styrene block and a diene block, and includes diblock copolymers, triblock copolymers, radial block copolymers, etc. Examples of diene block components include butadiene block and isoprene block. Specific examples of hydrogenated styrene-diene block copolymers include styrene-ethylene-butylene-styrene block copolymer (SEBS), which is a hydrogenated form of styrene-butadiene-styrene block copolymer (SBS); styrene-ethylene-propylene-styrene block copolymer (SEPS), which is a hydrogenated form of styrene-isoprene-styrene block copolymer (SIS); and styrene-ethylene-ethylene-propylene-styrene block copolymer (SEEPS), which is a hydrogenated form of styrene-butadiene / isoprene-styrene block copolymer (SBIS). The number-average molecular weight of the styrene-based elastomer used in the present invention is preferably 30,000 to 80,000, and more preferably 40,000 to 60,000.

[0028] The reason the olefin elastomer (B) is unmodified is to prevent it from reacting with the acid end-canceling agent (C), which will be discussed later. If an acid-modified olefin elastomer is incorporated, a complex reaction will occur between the acid end-canceling agent (C) and the acid-modified portion of the olefin elastomer, and between the acid end-canceling agent (C) and the acid end of the polyester elastomer (A). This will cause an extreme increase in viscosity and gelation, resulting in a deterioration of the appearance of the extruded product, which is undesirable.

[0029] In the present invention, when the total amount of polyester elastomer (A) and unmodified olefin-based elastomer (B) is 100 parts by mass, the mass ratio of polyester elastomer (A) to unmodified olefin-based elastomer (B) ((A) / (B)) is preferably 90 / 10 to 50 / 50. In order to significantly achieve the effects of the present invention, this mass ratio is preferably 80 / 20 to 55 / 45, more preferably 75 / 25 to 55 / 45, even more preferably 70 / 30 to 55 / 45, and particularly preferably 70 / 30 to 60 / 40. If the content of olefin-based elastomer (B) is small, the acid resistance will be insufficient, and if it is large, the heat aging resistance and extrusion moldability of the polyester elastomer resin composition will be insufficient.

[0030] [Cell-end sealant (C)] The acid end-canceling agent (C) used in the present invention is a compound having a functional group that can react with the terminal functional group of the polyester elastomer (A). The terminal functional group of the polyester elastomer (A) is a carboxyl group and / or a hydroxyl group. Examples of functional groups that can react with the acid end functional group of the polyester elastomer (A) include carboxyl groups, acid anhydride groups, epoxy groups, hydroxyl groups, carbodiimide groups, oxazoline groups, etc. Of these, the functional group of the acid end-canceling agent (C) is preferably an epoxy group or a carbodiimide group, considering the change in melt viscosity during melt retention and the reactivity with the acid end functional group of the polyester elastomer (A). Therefore, the acid end-canceling agent (C) is preferably an epoxy compound and / or a carbodiimide compound.

[0031] The epoxy compound used as the acid end-capping agent (C) is preferably a compound different from the epoxy group-containing polyolefin (D) described later, is a compound that does not have a polyolefin skeleton, and has a molecular weight of 10,000 or less. Examples of epoxy compounds include aliphatic epoxy compounds such as ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, butanediol diglycidyl ether, neopentyl glycol diglycidyl ether, hexanediol diglycidyl ether, glycerin diglycidyl ether, trimethylolpropane triglycidyl ether, and diglycerin tetraglycidyl ether, as well as dicyclopentadiene dioxide and epoxycyclohexenecarboxylic acid ethylene glycol. Examples include alicyclic epoxy compounds such as diesters, 3,4-epoxycyclohexenylmethyl-3'-4'-epoxycyclohexenecarboxylate, and 1,2:8,9-diepoxylimonene; bisphenol F type diepoxy compounds; bisphenol A type diepoxy compounds; epoxy compounds obtained by the reaction of polyphenol compounds with epichlorohydrin and their hydrogenated compounds; aromatic or heterocyclic epoxy compounds such as diglycidyl phthalates and triglycidyl isocyanurates; compounds having epoxy groups at the ends of silicone oils; and compounds having epoxy groups with alkoxysilanes.

[0032] As for epoxy compounds, diepoxy compounds are preferred from the viewpoint of reaction control and imparting extrudeability. Monoepoxy compounds do not have a chain extension effect and have little effect in imparting extrudeability. In addition, many have low volatilization temperatures, which can cause problems with gases during molding. Furthermore, while epoxy compounds with three or more functions have a great effect in imparting melt viscosity, reaction control and fluidity maintenance can be difficult.

[0033] As the epoxy compound, bisphenol F type diepoxy compounds are preferred. Compared to other epoxy compounds, bisphenol F type epoxy compounds have an excellent balance of epoxy equivalent and low volatility, so they maintain reactivity with the terminal functional groups of polyester elastomer (A) while being less prone to problems such as decomposition gases and associated appearance defects. Furthermore, for those that are liquid at room temperature and pressure, they exhibit both chain extension and plasticity effects simultaneously, so they have the advantage of easily exhibiting bending fatigue while maintaining fluidity, and it is preferable to use these compounds. Examples of such epoxy compounds that can be used include Epiclon 830 from DIC Corporation, and jER4004P, jER4005P, and jER4010P from Mitsubishi Chemical Corporation.

[0034] The carbodiimide compound used in this invention is a compound having at least one (-N=C=N-) carbodiimide group in its molecule, and which can react with the terminal groups of polyester elastomer (A).

[0035] Examples of carbodiimide compounds include diphenylcarbodiimide, dicyclohexylcarbodiimide, di-2,6-dimethylphenylcarbodiimide, diisopropylcarbodiimide, dioctyldecylcarbodiimide, di-o-toluylcarbodiimide, di-p-toluylcarbodiimide, di-p-nitrophenylcarbodiimide, di-p-aminophenylcarbodiimide, di-p-hydroxyphenylcarbodiimide, di-p-chlorophenylcarbodiimide, di-o-chlorophenylcarbodiimide, and di-3,4-dichlorophenylcarbodiimide. Lubodiimide, di-2,5-dichlorophenylcarbodiimide, p-phenylene-bis-o-toluylcarbodiimide, p-phenylene-bis-dicyclohexylcarbodiimide, p-phenylene-bis-di-p-chlorophenylcarbodiimide, 2,6,2',6'-tetraisopropyldiphenylcarbodiimide, hexamethylene-bis-cyclohexylcarbodiimide, ethylene-bis-diphenylcarbodiimide, ethylene-bis-dicyclohexylcarbodiimide, N,N'-di-o-toluylcarbodiimide, N,N'-diphenyl N,N'-Dioctyldecylcarbodiimide, N,N'-Di-2,6-Dimethylphenylcarbodiimide, N-Toluyl-N'-Cyclohexylcarbodiimide, N,N'-Di-2,6-Diisopropylphenylcarbodiimide, N,N'-Di-2,6-Di-tert-Butylphenylcarbodiimide, N-Toluyl-N'-Phenylcarbodiimide, N,N'-Di-p-Nitrophenylcarbodiimide, N,N'-Di-p-Aminophenylcarbodiimide, N,N'-Di-p-Hydroxyphenylcarbodiimide, N,N' -di-cyclohexylcarbodiimide, N,N'-di-p-toluylcarbodiimide, N,N'-benzylcarbodiimide, N-octadecyl-N'-phenylcarbodiimide, N-benzyl-N'-phenylcarbodiimide, N-octadecyl-N'-toluylcarbodiimide, N-cyclohexyl-N'-toluylcarbodiimide, N-phenyl-N'-toluylcarbodiimide, N-benzyl-N'-toluylcarbodiimide, N,N'-di-o-ethylphenylcarbodiimide, N,N'-di-p-ethylphenylcarbodiimide, N,Mono or dicarbodimide compounds such as N'-di-o-isopropylphenylcarbodiimide, N,N'-di-p-isopropylphenylcarbodiimide, N,N'-di-o-isobutylphenylcarbodiimide, N,N'-di-p-isobutylphenylcarbodiimide, N,N'-di-2,6-diethylphenylcarbodiimide, N,N'-di-2-ethyl-6-isopropylphenylcarbodiimide, N,N'-di-2-isobutyl-6-isopropylphenylcarbodiimide, N,N'-di-2,4,6-trimethylphenylcarbodiimide, N,N'-di-2,4,6-triisopropylphenylcarbodiimide, N,N'-di-2,4,6-triisobutylphenylcarbodiimide, poly(1,6-hexamethylenecarb) Examples of polycarbodiimides include poly(4,4'-methylenebiscyclohexylcarbodiimide), poly(1,3-cyclohexylenecarbodiimide), poly(1,4-cyclohexylenecarbodiimide), poly(4,4'-diphenylmethanecarbodiimide), poly(3,3'-dimethyl-4,4'-diphenylmethanecarbodiimide), poly(naphthylenecarbodiimide), poly(p-phenylenecarbodiimide), poly(m-phenylenecarbodiimide), poly(toluylcarbodiimide), poly(diisopropylcarbodiimide), poly(methyl-diisopropylphenylenecarbodiimide), poly(triethylphenylenecarbodiimide), and poly(triisopropylphenylenecarbodiimide). Among these, N,N'-di-2,6-diisopropylphenylcarbodiimide, 2,6,2',6'-tetraisopropyldiphenylcarbodiimide, and polycarbodiimide are preferred, and more preferably poly(1,6-hexamethylenecarbodiimide), poly(4,4'-methylenebiscyclohexylcarbodiimide), poly(1,3-cyclohexylenecarbodiimide), poly(1,4-cyclohexylenecarbodiimide), poly(4,4'-diphenylmethanecarbodiimide), and poly(3,3'-dimethyl-4,Examples of polycarbodiimides include 4'-diphenylmethanecarbodiimide, poly(naphthylenecarbodiimide), poly(p-phenylenecarbodiimide), poly(m-phenylenecarbodiimide), poly(toluylcarbodiimide), poly(diisopropylcarbodiimide), poly(methyl-diisopropylphenylenecarbodiimide), poly(triethylphenylenecarbodiimide), and poly(triisopropylphenylenecarbodiimide). Of these, polycarbodiimides are preferred from the viewpoint of improving heat aging resistance and hydrolysis resistance, and reactivity with acid ends, with poly(1,4-cyclohexylenecarbodiimide) and poly(triisopropylphenylenecarbodiimide) being particularly preferred.

[0036] When an acid end-canceling agent (C) is added, the content ratio is preferably 0.1 to 5 parts by mass, more preferably 0.1 to 4 parts by mass, and even more preferably 0.5 to 3.5 parts by mass, per 100 parts by mass of the total of polyester elastomer (A) and unmodified olefin-based elastomer (B). This component is added for the purpose of improving hydrolysis resistance and bending fatigue resistance by chain extension. However, if the amount is less than 0.1 parts by mass, these improvements are insufficient, while if it exceeds 5 parts by mass, a decrease in flame retardancy and a decrease in mechanical properties due to foreign matter effects may occur. Note that if a high molecular weight polyester elastomer (A) that does not require chain extension is used as the polyester elastomer (A), or if a polyester elastomer (A) with a sufficiently low terminal acid value is used, the amount of acid end-canceling agent (C) may be 0 parts by mass.

[0037] [Epoxy group-containing polyolefin (D)] The epoxy group-containing polyolefin (D) used in the present invention is a polyolefin resin that has been epoxy-modified, and preferably has an epoxy value of 0.01 to 0.5 meq / g. Similar to the epoxy compound of the acid end-canceling agent (C), the epoxy group-containing polyolefin (D) reacts with the end groups of the polyester elastomer (A) and acts as a compatibilizer, making the polyester elastomer (A) and the unmodified olefin elastomer (B) compatible. Furthermore, due to its appropriate epoxy value, the epoxy group-containing polyolefin (D) also contributes to stabilizing the melt viscosity during melt retention of the resin composition. The epoxy value of the epoxy group-containing polyolefin (D) is more preferably 0.05 to 0.5 meq / g, and even more preferably 0.1 to 0.5 meq / g. If the epoxy value is less than 0.01 meq / g, the compatibility with the polyester elastomer (A) decreases, the role as a compatibilizer is insufficient, and pulsation during extrusion molding may occur. When the epoxy value exceeds 0.5 meq / g, the melt viscosity increases during thermal retention, and these epoxy molecules gradually become coarse crosslinking points, which can lead to gelation.

[0038] As the epoxy group-containing polyolefin (D), a terpolymer consisting of α-olefin, an unsaturated compound other than α-olefin, and a glycidyl ester of an α,β-unsaturated acid is preferred. Examples of α-olefins include ethylene, propylene, and butene-1, with ethylene being particularly preferred. Examples of unsaturated compounds other than α-olefins include vinyl ethers, vinyl acetate, vinyl propionate and other vinyl esters, methyl, ethyl, propyl, and butyl esters of acrylic acid and methacrylic acid, acrylonitrile, and styrene, with butyl acrylate, methyl acrylate, and methyl methacrylate being particularly preferred. Furthermore, examples of glycidyl esters of α,β-unsaturated acids include glycidyl acrylate, glycidyl methacrylate, and glycidyl ethanolate, with glycidyl methacrylate being particularly preferred.

[0039] When epoxy group-containing polyolefin (D) is added, the amount added is preferably 1 to 10 parts by mass, more preferably 1 to 9 parts by mass, even more preferably 2 to 8 parts by mass, and particularly preferably 3 to 7 parts by mass, based on 100 parts by mass of the total of polyester elastomer (A) and unmodified olefin-based elastomer (B). If the amount added is less than 1 part by mass, it does not show the effect of a compatibilizer, and if it exceeds 10 parts by mass, the acid end of the polyester elastomer (A) and the epoxy group may react during retention, causing gelation. Furthermore, when epoxy group-containing polyolefin (D) is not added, depending on the type and amount of olefin-based elastomer (B), extrusion molding is not impossible, but depending on the extrusion molding conditions, some pulsation may be observed. However, by using 1 to 10 parts by mass of epoxy group-containing polyolefin (D) in combination, extrusion moldability can be improved, and the influence of the type and amount of olefin-based elastomer (B) can be significantly reduced.

[0040] [Flame retardant] The polyester elastomer resin composition of the present invention may optionally contain either a halogen-based flame retardant or a non-halogen-based flame retardant.

[0041] [Bromine-based flame retardant (E)] Examples of halogen-based flame retardants used in the present invention include brominated flame retardants (E). Brominated flame retardants (E) include hexabromocyclododecane, decabromodiphenyl oxide, octabromodiphenyl oxide, tetrabromobisphenol A, bis(tribromophenoxy)ethane, bis(pentabromophenoxy)ethane, tetrabromobisphenol A epoxy resin, tetrabromobisphenol A carbonate, ethylene(bistetrabromophthal)imide, ethylenebispentabromodiphenyl, tris(tribromophenoxy)triazine, bis(dibromopropyl)tetrabromobisphenol A, bis(dibromo Examples include propyl)tetrabromobisphenol S, brominated polyphenylene ethers (including poly(di)bromophenylene ethers, 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, tetrabromobisphenol S, tris(tribromoneopentyl)phosphate, polybromotrimethylphenylindan, and tris(dibromopropyl)-isocyanurate. Among these, brominated polystyrene is preferred in terms of compatibility with polyester elastomer (A).

[0042] [Flame retardant additive (F)] In the present invention, an antimony oxide compound is preferably used as the flame retardant additive (F). Examples of antimony oxide compounds include antimony trioxide, antimony pentoxide, or sodium antimonate. The content of the brominated flame retardant (E) and the flame retardant aid (F) is preferably 5 to 30 parts by mass in total, based on 100 parts by mass of the polyester elastomer (A) and the unmodified olefin elastomer (B). By using amounts of the brominated flame retardant (E) and the flame retardant aid (F) within this range, a polyester elastomer resin composition with particularly excellent flame retardancy can be prepared.

[0043] [Phosphorus-based flame retardant (G)] Examples of non-halogenated flame retardants used in the present invention include phosphorus-based flame retardants. Generally, phosphorus-based flame retardants include organophosphorus compounds and inorganic phosphorus compounds. The phosphorus-based flame retardant (G) used in the present invention is broadly classified into organophosphorus compounds and inorganic phosphorus compounds. Examples of organophosphorus compounds include phosphates, phosphonates, phosphinates, and phosphites, specifically trimethyl phosphate, triethyl phosphate, tributyl phosphate, trioctyl phosphate, tributoxyethyl phosphate, octyldiphenyl phosphate, tricresyl phosphate, cresyldiphenyl phosphate, triphenyl phosphate, trixylenyl phosphate, tris-isopropylphenyl phosphate, diethyl-N,N-bis(2-hydroxyethyl)aminomethylphosphonate, and bis(1,3-phenylenediphenyl) phosphate. Among these, metal phosphinate salts are preferred from the viewpoint of flame retardancy, and aluminum phosphinate salts are particularly preferred. Examples of inorganic phosphorus compounds include red phosphorus compounds and inorganic phosphate compounds such as (poly)ammonium phosphate, (poly)melamine phosphate, and (poly)piperazine phosphate.

[0044] As the phosphorus-based flame retardant (G), a phosphorus-based flame retardant having an average particle size D50 of 20 μm or less and a phosphorus concentration of 15% by mass or more can be used. Regarding the average particle size D50, using a larger particle size tends to worsen the surface smoothness of the extruded product. Regarding the phosphorus concentration, flame retardants with low phosphorus concentrations tend to have little flame-retardant effect, requiring the addition of large amounts, making it difficult to achieve both flame retardancy and other properties. The average particle size D50, also called the median diameter, can be measured and analyzed using a laser diffraction particle size distribution analyzer, and the phosphorus concentration can be measured (calculated) by ICP emission spectrometry. The average particle size D50 is preferably 16 μm or less, and more preferably 12 μm or less. There is no particular limit to the lower limit of the average particle size D50, but it is preferably 0.1 μm or more. The phosphorus concentration is preferably 18% by mass or more, and more preferably 20% by mass or more. There is no particular limit to the upper limit of the phosphorus concentration, but it is preferably 30% by mass or less.

[0045] The content of the phosphorus-based flame retardant (B) is preferably 5 to 50 parts by mass, more preferably 8 to 40 parts by mass, even more preferably 10 to 35 parts by mass, and particularly preferably 15 to 30 parts by mass, based on 100 parts by mass of the total of the polyester elastomer (A) and the unmodified olefin-based elastomer (B). If the content of the phosphorus-based flame retardant (B) is less than 5 parts by mass, the flame retardancy is insufficient, and if the content exceeds 50 parts by mass, problems such as a decrease in mechanical properties may occur. Furthermore, the polyester elastomer resin composition of the present invention may optionally contain non-halogenated flame retardants other than phosphorus-based flame retardants. Examples of non-halogenated flame retardants other than phosphorus-based flame retardants include nitrogen-based flame retardants, silicon-based flame retardants, metal hydroxides, metal booxides, and the like.

[0046] [Polyester elastomer resin composition] The carboxyl group concentration in the polyester elastomer resin composition of the present invention is 10 eq / ton or less. A carboxyl group concentration of 7 eq / ton or less is preferred, and 5 eq / ton or less is more preferred. A carboxyl group concentration of 0 eq / ton in the polyester elastomer resin composition is also a preferred embodiment. A carboxyl group concentration exceeding 10 eq / ton is undesirable because it impairs hydrolysis resistance.

[0047] The polyester elastomer resin composition of the present invention may optionally contain general-purpose antioxidants such as aromatic amine-based, hindered phenol-based, phosphorus-based, and sulfur-based antioxidants.

[0048] Furthermore, if weather resistance is required for the polyester elastomer resin composition of the present invention, it is preferable to add an ultraviolet absorber and / or a hindered amine compound. For example, benzophenone-based, benzotriazole-based, triazole-based, nickel-based, and salicyl-based light stabilizers can be used. Specifically, 2,2'-dihydroxy-4-methoxybenzophenone, 2-hydroxy-4-n-octoxybenzophenone, pt-butylphenyl salicylate, 2,4-di-t-butylphenyl-3,5-di-t-butyl-4-hydroxybenzoate, 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-3',5'-di-t-amylphenyl)benzotriazole, 2-[2'-hydroxy-3',5'-bis( α,α-dimethylbenzylphenyl)benzotriazole, 2-(2'-hydroxy-3'-t-butyl-5'-methylphenyl)-5-chlorobenazotriazole, 2-(2'-hydroxy-3',5'-di-t-butylphenyl)-5-chlorobenzothiriazole, 2,5-bis-[5'-t-butylbenzoxazolyl-(2)]-thiophene, bis(3,5-di-t-butyl-4-hydroxybenzylphosphate monoethyl ester) nickel salt, 2-ethoxy-5- A mixture of 85-90% t-butyl-2'-ethyl oxalic acid bis-anilide and 10-15% 2-ethoxy-5-t-butyl-2'-ethyl-4'-t-butyl oxalic acid bis-anilide, 2-[2-hydroxy-3,5-bis(α,α-dimethylbenzyl)phenyl]-2H-benzotriazole, 2-ethoxy-2'-ethyl oxalic acid bis-anilide, 2-[2'-hydrooxy-5'-methyl-3'-(3'',4'',5' Examples of light stabilizers include ',6''-tetrahydrophthalimidomethyl)phenyl]benzotriazole, bis(5-benzoyl-4-hydroxy-2-methoxyphenyl)methane, 2-(2'-hydroxy-5'-t-octylphenyl)benzotriazole, 2-hydroxy-4-i-octoxybenzophenone, 2-hydroxy-4-dodecyloxybenzophenone, 2-hydroxy-4-octadecyloxybenzophenone, and phenyl salicylate.The content is preferably 0.1% by mass or more and 5% by mass or less, based on the mass of the polyester elastomer resin composition.

[0049] The polyester elastomer resin composition of the present invention may contain various other additives. Additives may include resins other than polyester elastomer (A), inorganic fillers, stabilizers, and antioxidants, provided they do not impair the characteristics of the present invention. Other additives that may be added include coloring pigments, inorganic and organic fillers, coupling agents, tack enhancers, quenchers, metal deactivators and other stabilizers, and flame retardants. The polyester elastomer resin composition of the present invention preferably contains 75% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more, of the total of polyester elastomer (A), unmodified olefin elastomer (B), acid end-capping agent (C), and epoxy group-containing polyolefin resin (D) (acid end-capping agent (C) and epoxy group-containing polyolefin resin (D) are optional components).

[0050] The polyester elastomer resin composition obtained by the present invention has excellent acid resistance and heat aging resistance, and furthermore, it can retain the inherent flexibility, moldability, chemical resistance, bending fatigue resistance, abrasion resistance, electrical properties, and other properties of polyester elastomer, so it can be applied to a wide range of electrical product components, hoses, tubes, cable coverings, etc. In particular, its application to cable coverings is useful. In addition, the polyester elastomer resin composition obtained by the present invention can be molded into various shapes by injection molding, transfer molding, blow molding, etc., in addition to extrusion molding. [Examples]

[0051] Examples are given below to further illustrate the present invention, but the present invention is not limited in any way by these examples. The measurements described in the examples were taken by the following method.

[0052] [Melting point] Using a differential scanning calorimetry analyzer "DSC220" manufactured by Seiko Electronics Industries, Ltd., 5 mg of the sample was placed in an aluminum pan, sealed by pressing down on the lid, and held at 250°C for 5 minutes to completely melt the sample. After rapid cooling with liquid nitrogen, measurements were taken from -150°C to 250°C at a heating rate of 20°C / min. The endothermic peak temperature obtained from the resulting thermogram curve was defined as the melting point.

[0053] [Reduced viscosity] 0.05 g of the sample was dissolved in 25 mL of a mixed solvent (phenol / tetrachloroethane = 60 / 40 (mass ratio)) and measured at 30°C using an Ostwald viscometer.

[0054] [End acid value] The terminal acid value (eq / t) of polyester elastomer (A) was determined by dissolution titration, in which 200 mg of a thoroughly dried sample (polyester elastomer) was dissolved in 10 mL of hot benzyl alcohol, the resulting solution was cooled, and then 10 mL of chloroform and phenol red were added, followed by titration with a 1 / 25 N KOH ethanol solution.

[0055] The raw materials used in the examples are as follows: [Polyester elastomer (A)] (Polyester elastomer A-1) 100 parts by mass of aliphatic polycarbonate diol (UH-CARB200, Ube Industries, Ltd., molecular weight 2000, 1,6-hexanediol type) and 8.9 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 aliphatic polycarbonate diol (number average molecular weight 12000). 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 30000 were stirred at 230°C to 245°C and 130 Pa for 1 hour. After confirming that the resin had become transparent, the contents were removed and cooled to produce a polyester elastomer. The melting point of this polyester elastomer A-1 was 207°C, the reduced viscosity was 1.21 dl / g, and the terminal acid value was 44 eq / ton.

[0056] (Polyester elastomer A-2) 100 parts by mass of aliphatic polycarbonate diol (UH-CARB200, Ube Industries, Ltd., molecular weight 2000, 1,6-hexanediol type) and 8.9 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 aliphatic polycarbonate diol (number average molecular weight 12000). 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 30000 were stirred at 230°C to 245°C and 130 Pa for 1 hour. After confirming that the resin had become transparent, the contents were removed. The removed pellets were heated at 170 to 180°C and solid-phase polycondensation was performed to produce a polyester elastomer. The melting point of this polyester elastomer A-2 was 208°C, its reducing viscosity was 1.21 dl / g, and its terminal acid value was 7 eq / ton.

[0057] (Polyester elastomer A-3) 100 parts by mass of aliphatic polycarbonate diol (UH-CARB200, 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 aliphatic polycarbonate diol (number average molecular weight 10000). 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 30000 were stirred at 230°C to 245°C and 130 Pa for 1 hour. After confirming that the resin had become transparent, the contents were removed and cooled to produce a polyester elastomer. The melting point of this polyester elastomer A-3 was 212°C, the reduced viscosity was 1.20 dl / g, and the terminal acid value was 41 eq / ton.

[0058] (Polyester Elastomer A-4): Comparative Polyester Elastomer A polyester elastomer was prepared 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%). This polyester elastomer A-4 had a melting point of 203°C, a reduced viscosity of 1.75 dl / g, and a terminal acid value of 50 eq / ton.

[0059] (Polyester elastomer A-5) A polyester-polyester block copolymer (polyester elastomer A-5) was produced by heating and mixing 100 parts by mass of polybutylene terephthalate and 46 parts by mass of ε-caprolactone at 250°C, and then carrying out a transesterification reaction in a reaction vessel for 60 minutes while ring-opening polymerization of the lactone. The melting point was 214°C, the reduced viscosity was 1.30 dl / g, and the terminal acid value was 60 eq / ton. Table 1 shows the physical properties of each polyester elastomer.

[0060] [Table 1]

[0061] [Olefin-based elastomer (B)] (B-1) Styrene-ethylene-butylene-styrene block copolymer: ToughTec H1221, manufactured by Asahi Kasei Corporation, styrene / ethylene-butylene ratio = 12 / 88 (mass ratio), MFR (190℃, 2.16kg) = 4.5g / 10min (B-2) Maleic anhydride-modified styrene-ethylene-butylene-styrene block copolymer: ToughTec M1943, manufactured by Asahi Kasei Corporation, styrene / ethylene-butylene ratio = 20 / 80 (mass ratio), MFR (190℃, 2.16kg) = 8.0g / 10min, acid value = 10eq / t, olefin-based elastomer for comparison. (B-3) Ethylene-methyl methacrylate copolymer: Rotrill 29MA03T, manufactured by Arkema, ethylene / methyl methacrylate ratio = 71 / 29 (mass ratio), MFR (190℃, 2.16kg) = 3.0g / 10min

[0062] [Cell-end sealant (C)] (C-1) Alicyclic polycarbodiimide: Carbodilite HMV-15CA, manufactured by Nisshinbo Chemical Co., Ltd. (C-2) Bisphenol F type diepoxy compound: Epiclon 830, manufactured by DIC Corporation

[0063] [Epoxy group-containing polyolefin (D)] (D-1) Epoxy group-containing olefin copolymer: Bondfast BF-7M, manufactured by Sumitomo Chemical Co., Ltd., epoxy value: 0.4 meq / g

[0064] [Bromine-based flame retardant (E)] (E-1) Brominated polystyrene: PDBS-80, manufactured by Lanxess Corporation [Flame retardant additive (F)] (F-1) Antimony Trioxide: Twinkling Star, manufactured by China Industrial Co., Ltd.

[0065] [Phosphorus-based flame retardant (G)] (G-1) Aluminum diethylphosphinate: EXOLIT OP930, D50 is 4 μm, phosphorus concentration is 23% by mass, manufactured by Clariant Co., Ltd. (G-2) Aluminum diethylphosphinate: EXOLIT OP1230, D50 is 30 μm, phosphorus concentration is 23% by mass, manufactured by Clariant Co., Ltd. The average particle size D50 was measured using a laser diffraction particle size analyzer, and the phosphorus concentration was measured (calculated) using ICP emission spectrometry.

[0066] Examples 1-13, Comparative Examples 1-5 The above raw materials were kneaded and pelletized in the proportions shown in Table 2 using a twin-screw extruder. The following evaluations were performed using these polyester elastomer resin pellets. The results are shown in Table 2.

[0067] [Extruderability (pulsation)] The pellets, which had been melt-kneaded in a twin-screw extruder, were then extruded again from a circular die using a single-screw extruder to produce strands with a diameter of 3 mm. The extrusion moldability of these strands was then evaluated according to the following criteria. ○: No fluctuations in discharge volume, and extrusion properties are stable. △: While stable when being pulled at a constant speed using a pull-up machine, slight fluctuations in discharge volume are observed when it is hanging down under its own weight. ×: Discharge volume fluctuates significantly, making collection impossible. [Extruderability (smoothness)] Pellets, melt-kneaded in a twin-screw extruder, were then extruded again from a T-die using a single-screw extruder to produce 0.2 mm thick sheet molded products. The smoothness of the extruded products was evaluated from the appearance of the sheets according to the following criteria. ○: No roughness or foaming occurs, and the sheet appearance and surface smoothness are excellent. △: No sheet irregularities (melt fracture) or foaming occur, but there is a uniform roughness similar to a textured finish. ×: Sheet irregularities (melt fracture) and foaming occur, resulting in an unsatisfactory appearance.

[0068] [Heat resistance to elongation at 170℃ (half-life)] Test specimens conforming to JIS dumbbell-shaped type 3 were left in a 170°C environment for a predetermined time, then removed, and the tensile elongation at break was measured in accordance with JIS K6251:2010. The test specimens were made by injection molding a 100mm × 100mm × 2mm flat plate using an injection molding machine (Yamashiro Seiki Co., Ltd., model-SAV) with a cylinder temperature (Tm + 20°C) and a mold temperature of 30°C, from which dumbbell-shaped type 3 test specimens were punched out. The tensile elongation retention rate was calculated using the following formula, and the time it took for this value to drop to 50% (tensile elongation half-life) was used as an indicator of heat aging resistance. The initial tensile elongation is the tensile elongation before heat treatment. Tensile elongation retention rate (%) = Tensile elongation after heat treatment / Initial tensile elongation × 100

[0069] [Acid resistance] A 37% sulfuric acid aqueous solution was dropped onto a 3mm thick flat molded product, and heat-treated at 90°C for 8 hours. Then, sulfuric acid was dropped onto the same spot again, and heat-treated at 90°C for 16 hours. This cycle constituted one cycle, and a total of two cycles were performed. At the dropping site, carbonization of the molded product progressed due to the sulfuric acid concentrated by the heat treatment, and the depth of the resulting erosion was measured from the cross-section. The flat molded product was obtained by injection molding a 100mm x 100mm x 3mm flat plate using an injection molding machine (Yamashiro Seiki Co., Ltd., model-SAV) with a cylinder temperature (Tm + 20°C) and a mold temperature of 30°C, from pellets of a resin composition dried under reduced pressure at 100°C for 8 hours.

[0070] [Carboxyl group concentration] The carboxyl group concentration (eq / t) of the polyester elastomer resin composition was determined by dissolution titration, similar to the terminal acid value of polyester elastomer (A). This method involved dissolving 200 mg of a thoroughly dried sample 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 KOH ethanol solution.

[0071] [Table 2]

[0072] As is clear from the results in Table 2, the polyester elastomer resin compositions of the present invention shown in Examples 1 to 13 possess excellent acid resistance and heat aging resistance, while also exhibiting good extrusion moldability. In particular, a comparison between Example 2 and Example 6 shows that increasing the hard segment ratio in the polyester elastomer further improves acid resistance. In Example 8, although some types of olefin-based elastomer (B) do not make extrusion molding impossible, some slight pulsation is observed. However, as shown in Example 9, the use of epoxy group-containing polyolefin (D) in combination improves extrusion moldability. In Example 12, a slight decrease in smoothness is observed, but this is not due to the combination of compounds, but rather indicates that the large particle size of the phosphorus-based flame retardant (G) results in a slightly uniform roughness similar to that of a textured finish. On the other hand, the compositions of Comparative Examples 1 to 5, which do not meet the conditions of the present invention, are inferior to the compositions of the present invention in either extrusion moldability, acid resistance, or heat aging resistance.

[0073] Comparative Example 1, which does not contain olefin-based elastomer (B), exhibits poor acid resistance. On the other hand, Comparative Example 2, which contains an excess amount of olefin-based elastomer (B), shows good acid resistance, but exhibits pulsation during extrusion molding, as well as a significant decrease in heat aging resistance. Comparative Example 3, which uses a polyester elastomer with aliphatic polyether soft segments, exhibits poor heat aging resistance. Comparative Examples 4 and 5, which use acid-modified olefin-based elastomers, show that the smoothness of the extruded product is impaired regardless of whether the acid end-sealing agent (C) is epoxy-based or carbodiimide-based, and that acid resistance is slightly lower compared to Examples 2 and 3. [Industrial applicability]

[0074] Thus, the polyester elastomer resin composition of the present invention exhibits excellent acid resistance and heat aging resistance, while also possessing good outer diameter stability and surface smoothness even in extrusion molding. For this reason, it can be applied to a wide range of applications, such as various components of electrical products, hoses, tubes, and cable coverings. In addition, the resin composition obtained by the present invention can be molded into various shapes by injection molding, transfer molding, blow molding, etc.

Claims

1. A polyester elastomer resin composition comprising 50 to 90 parts by mass of a polyester elastomer (A) comprising a hard segment made of a polyester composed of an aromatic dicarboxylic acid and an aliphatic and / or alicyclic diol, and a soft segment selected from aliphatic polyester and aliphatic polycarbonate, 10 to 50 parts by mass of an unmodified olefin-based elastomer (B), and further comprising 0.1 to 5 parts by mass of an acid end-canceling agent (C) per 100 parts by mass of the total of the polyester elastomer (A) and the unmodified olefin-based elastomer (B), characterized in that the carboxyl group concentration in the resin composition is 10 eq / ton or less, the erosion depth in an acid resistance test is 1.2 mm or less, the heat resistance elongation half-life at 170°C is 500 hours or more, and the hard segment of the polyester elastomer (A) does not contain isophthalic acid as a component.

2. The polyester elastomer resin composition according to claim 1, further containing 1 to 10 parts by mass of epoxy group-containing polyolefin (D) per 100 parts by mass of polyester elastomer (A) and unmodified olefin-based elastomer (B).

3. The polyester elastomer resin composition according to claim 1 or 2, wherein the unmodified olefin-based elastomer (B) is an elastomer containing styrene as a copolymer component.

4. The polyester elastomer resin composition according to any one of claims 1 to 3, wherein the polyester elastomer (A) is a copolymer having a melting point of 150 to 230°C, with terephthalic acid, 1,4-butanediol, and aliphatic polycarbonate diol as the main components.

5. A polyester elastomer resin composition according to any one of claims 1 to 4, further containing 5 to 30 parts by mass of a brominated flame retardant (E) and a flame retardant aid (F) in addition to 100 parts by mass of a total of polyester elastomer (A) and unmodified olefin-based elastomer (B).

6. A polyester elastomer resin composition according to any one of claims 1 to 4, further containing 5 to 50 parts by mass of a phosphorus-based flame retardant (G) per 100 parts by mass of a total of polyester elastomer (A) and unmodified olefin-based elastomer (B).

7. The polyester elastomer resin composition according to claim 6, wherein the phosphorus-based flame retardant (G) has an average particle size D50 of 20 μm or less and a phosphorus concentration of 15% by mass or more.

8. A polyester elastomer resin composition according to any one of claims 1 to 7, for use as a cable sheath.

9. A cable covering material comprising the polyester elastomer resin composition according to any one of claims 1 to 7.

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