JP7658127B2 - Polyester elastomer resin composition and cable covering material made thereof - Google Patents

Description

The present invention relates to a polyester elastomer composition for extrusion molding that has excellent acid resistance and hydrolysis resistance.

Thermoplastic polyester elastomers that have been known and put to practical use include those that use crystalline polyesters such as polybutylene terephthalate (PBT) and polybutylene naphthalate (PBN) as hard segments and polyoxyalkylene glycols such as polytetramethylene glycol (PTMG) and/or polyesters such as polycaprolactone (PCL) and polybutylene adipate (PBA) as soft segments (see, for example, Patent Documents 1 and 2).

Furthermore, in recent years, polyester polycarbonate type elastomers using polycarbonate in the soft segment have been proposed (see, for example, Patent Documents 3 to 7), and are known to have heat aging resistance and hydrolysis resistance superior to conventional polyester polyether type elastomers using polyoxyalkylene glycols in the soft segment and polyester polyester type elastomers using polyester in the soft segment.

In the future, electric vehicles are expected to take over from conventional gasoline-powered vehicles in the automotive industry, which is expected to lead to an increase in the number of in-vehicle cables. Polyester elastomers, which have a long track record in wire coating applications, are expected to be a material for next-generation in-vehicle cables due to their excellent properties. However, a prerequisite for this application is the need to pass a battery fluid (sulfuric acid) drip test, and in reality, existing conventional polyester elastomers have not been able to pass this test. In addition, high hydrolysis resistance is also required for this application.

Japanese Patent Application Publication No. 10-17657 JP 2003-192778 A Special Publication No. 7-39480 Japanese Patent Application Publication No. 10-182782 JP 2001-206939 A JP 2001-240663 A Patent No. 4244067

The present invention was devised in view of the current state of the prior art, and its purpose is to provide a polyester elastomer composition that has excellent acid resistance and hydrolysis resistance and is suitable for extrusion molding. In particular, it is an object of the present invention to provide a polyester elastomer composition that is suitable for use as a cable coating material by extrusion molding.

In order to achieve the above object, the inventors conducted extensive research into polyester elastomer compositions with excellent acid resistance and hydrolysis resistance, and finally completed the present invention.

That is, the present invention is as follows.
[1] A polyester elastomer resin composition comprising 50 to 90 parts by mass of a polyester elastomer (A) having a hard segment made of a polyester containing an aromatic dicarboxylic acid and an aliphatic and/or alicyclic diol as constituent components, and a soft segment made of an aliphatic polyether, 10 to 50 parts by mass of an unmodified olefin-based elastomer (B), and further comprising 0 to 5 parts by mass of an acid end-blocking agent (C) per 100 parts by mass in total of the polyester elastomer (A) and the unmodified olefin-based elastomer (B), wherein the polyester elastomer resin composition has a carboxyl group concentration of 10 eq/ton or less.
[2] The polyester elastomer resin composition according to [1], further comprising 1 to 10 parts by mass of an epoxy group-containing polyolefin (D) per 100 parts by mass of the total of the polyester elastomer (A) and the unmodified olefin elastomer (B).
[3] The polyester elastomer resin composition according to [1] or [2], wherein the unmodified olefin-based elastomer (B) is an elastomer containing styrene as a copolymerization component.
[4] The polyester elastomer resin composition according to any one of [1] to [3], wherein the soft segment in the polyester elastomer (A) is poly(tetramethylene oxide) glycol (PTMG) and/or an ethylene oxide addition polymer of poly(propylene oxide) glycol (PPG-EO addition polymer).
[5] The polyester elastomer resin composition according to any one of [1] to [4], further comprising a brominated flame retardant (E) and a flame retardant auxiliary (F) in a total amount of 5 to 30 parts by mass per 100 parts by mass of the polyester elastomer (A) and the unmodified olefin-based elastomer (B).
[6] The polyester elastomer resin composition according to any one of [1] to [4], further comprising 5 to 30 parts by mass of a phosphorus-based flame retardant (G) per 100 parts by mass in total of the polyester elastomer (A) and the 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 mass% or more.
[8] The polyester elastomer resin composition according to any one of [1] to [7], which is for use in cable coating.
[9] A cable covering material comprising the polyester elastomer resin composition according to any one of [1] to [7].

The polyester elastomer resin composition of the present invention has excellent acid resistance and hydrolysis resistance, and also has good outer diameter stability and surface smoothness even when extruded.

[Polyester elastomer (A)]
The polyester elastomer (A) used in the present invention mainly comprises a hard segment made of a polyester having an aromatic dicarboxylic acid and an aliphatic and/or alicyclic diol as constituent components, and a soft segment made of an aliphatic polyether. As the hard segment, the polyester made of an aromatic dicarboxylic acid and an aliphatic and/or alicyclic diol is preferably 70% by mass or more, more preferably 80% by mass or more, and may be 100% by mass. As the soft segment, the aliphatic polyether is preferably 70% by mass or more, more preferably 80% by mass or more, and may be 100% by mass.

In the polyester elastomer (A) used in the present invention, the aromatic dicarboxylic acid constituting the polyester of the hard segment is generally a normal aromatic dicarboxylic acid, and is not particularly limited. However, it is desirable that the main aromatic dicarboxylic acid is terephthalic acid or 2,6-naphthalenedicarboxylic acid. Terephthalic acid or 2,6-naphthalenedicarboxylic acid is preferably 70 mol% or more of the total acid components, more preferably 80 mol% or more. Examples of other acid components include aromatic dicarboxylic acids such as diphenyldicarboxylic acid, isophthalic acid, and 5-sodium sulfoisophthalic acid, alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid and tetrahydrophthalic anhydride, and aliphatic dicarboxylic acids such as succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, dimer acid, and hydrogenated dimer acid. The other acid components are used in a range that does not significantly lower the melting point of the polyester elastomer (A), and the amount is preferably 30 mol% or less of the total acid components, more preferably 20 mol% or less.

In the polyester elastomer (A) used in the present invention, the aliphatic or alicyclic diol constituting the polyester of the hard segment is generally aliphatic or alicyclic diol, and although there is no particular limitation, it is preferably an alkylene glycol having 2 to 8 carbon atoms. Specific examples include ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol, and 1,4-cyclohexanedimethanol. Of these, 1,4-butanediol or 1,4-cyclohexanedimethanol is preferred.

As the components constituting the polyester of the hard segment, those composed of butylene terephthalate units consisting of terephthalic acid and 1,4-butanediol, or those composed of butylene naphthalate units consisting of 2,6-naphthalenedicarboxylic acid and 1,4-butanediol are preferred in terms of physical properties, moldability, and cost performance. Those composed of butylene terephthalate units are particularly preferred.

In addition, when an aromatic polyester suitable 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 a normal polyester production method. In addition, such a polyester preferably has a number average molecular weight of 10,000 to 40,000.

The aliphatic polyethers that are the soft segment components in the polyester elastomer (A) used in the present invention include poly(alkylene oxide) glycols such as poly(ethylene oxide) glycol, poly(propylene oxide) glycol, poly(tetramethylene oxide) glycol, poly(hexamethylene oxide) glycol, copolymers of ethylene oxide and propylene oxide, ethylene oxide addition polymers of poly(propylene oxide) glycol, and copolymers of ethylene oxide and tetrahydrofuran.

Among the above aliphatic polyethers, poly(tetramethylene oxide) glycol (PTMG), ethylene oxide addition polymer of poly(propylene oxide) glycol (PPG-EO addition polymer), and copolymer glycol of ethylene oxide and tetrahydrofuran (EO/THF copolymer glycol) are preferred, and poly(tetramethylene oxide) glycol (PTMG) and ethylene oxide addition polymer of poly(propylene oxide) glycol (PPG-EO addition polymer) are more preferred. Furthermore, the number average molecular weight of these soft segments in the copolymerized state is preferably about 300 to 6000.

The soft segment content (copolymerization amount) of the polyester elastomer (A) used in the present invention is preferably 3 to 60 mass% in the polyester elastomer (A). The soft segment content is more preferably 5 to 60 mass%, further preferably 10 to 50 mass%, and particularly preferably 20 to 40 mass%. If the soft segment content (copolymerization amount) is less than 5 mass%, the flexibility, rubber elasticity, and hydrolysis resistance of the elastomer are insufficient, and if it exceeds 60 mass%, acid resistance tends to decrease.

The reduced viscosity of the polyester elastomer (A) used in the present invention is preferably 1.3 to 2.5 dl/g, more preferably 1.5 to 2.3 dl/g. The melting point of the polyester elastomer (A) used in the present invention is preferably 170 to 225°C, more preferably 170 to 220°C, and even more preferably 180 to 210°C.

The polyester elastomer (A) used in the present invention can be produced by known methods. For example, there is a method in which a lower alcohol diester of a dicarboxylic acid, an excess amount of an aliphatic and/or alicyclic diol, and a soft segment component are subjected to an ester exchange reaction in the presence of a catalyst, and the resulting reaction product is polycondensed, and a method in which a dicarboxylic acid, an excess amount of an aliphatic and/or alicyclic diol, and a soft segment component are subjected to an esterification reaction in the presence of a catalyst, and the resulting reaction product is polycondensed.

[Unmodified olefin-based elastomer (B)]
The olefin elastomer (B) in the present invention refers to a block copolymer containing an olefin compound as a constituent component. Here, the olefin compound is 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, 3-methyl-1-pent ... Examples of the olefin-based elastomer (B) include α-olefins such as styrene, 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, and conjugated dienes such as butadiene and isoprene. The olefin-based elastomer (B) may contain, in addition to the olefin compound, 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 constituents.
Here, "unmodified" means that the olefin elastomer obtained from the above constituent components is not modified with a compound containing a functional group such as a carboxyl group, which is a terminal functional group of the polyester elastomer (A), a carboxyl group that reacts with a hydroxyl group, an acid anhydride group, an epoxy group, a hydroxyl group, a carbodiimide group, an oxazoline group, etc., that is, a compound containing such a functional group is not copolymerized. Hydrogenation of the double bonds remaining in the olefin elastomer is not included in the modification.

Moreover, the unmodified olefin-based elastomer (B) used in the present invention is more preferably an elastomer containing styrene as a copolymerization component, i.e., a so-called styrene-based elastomer. A styrene-based elastomer is a hydrogenated product of a 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 a diblock copolymer, a triblock copolymer, a radial block copolymer, etc. Furthermore, examples of the diene block component include a butadiene block and an isoprene block. Specific examples of hydrogenated styrene-diene block copolymers include styrene-ethylene-butylene-styrene block copolymer (SEBS), which is a hydrogenated product of styrene-butadiene-styrene block copolymer (SBS), styrene-ethylene-propylene-styrene block copolymer (SEPS), which is a hydrogenated product of styrene-isoprene-styrene block copolymer (SIS), and styrene-ethylene-ethylene-propylene-styrene block copolymer (SEEPS), which is a hydrogenated product 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.

The reason why the olefin-based elastomer (B) is unmodified is to prevent reaction with the acid end-capping agent (C) described below. If an acid-modified olefin-based elastomer is blended, the acid end-capping agent (C) will react with the acid-modified portion of the olefin-based elastomer, and the acid end-capping agent (C) will react with the acid end of the polyester elastomer (A), causing an extreme increase in viscosity and gelation, which will deteriorate the appearance of the extrusion molded product, and is therefore undesirable.

In the present invention, when the total of the polyester elastomer (A) and the unmodified olefin-based elastomer (B) is 100 parts by mass, the mass ratio ((A)/(B)) of the polyester elastomer (A) to the unmodified olefin-based elastomer (B) is preferably 90/10 to 50/50. In order to achieve the effects of the present invention significantly, 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 the olefin-based elastomer (B) is small, the acid resistance is insufficient, and if it is large, the extrusion moldability of the polyester elastomer resin composition is insufficient, which is not preferable.

[Acid end-capping agent (C)]
The acid end-capping agent (C) used in the present invention is a compound having a functional group capable of reacting 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 the functional group capable of reacting with the acid terminal functional group of the polyester elastomer (A) include a carboxyl group, an acid anhydride group, an epoxy group, a hydroxyl group, a carbodiimide group, and an oxazoline group. Among these, the functional group of the acid end-capping agent (C) is preferably an epoxy group or a carbodiimide group in view of the change in melt viscosity during melt retention and the reactivity with the acid terminal functional group of the polyester elastomer (A). Therefore, the acid end-capping agent (C) is preferably an epoxy compound and/or a carbodiimide compound.

The epoxy compound used as the acid end blocking agent (C) is a compound different from the epoxy group-containing polyolefin (D) described below, is a compound having no polyolefin skeleton, and preferably 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; dicyclopentadiene dioxide; and epoxycyclohexene carboxylic acid ethylene glycol. Examples of the epoxy compounds 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 reacting polyphenol compounds with epichlorohydrin and hydrogenated compounds thereof, aromatic or heterocyclic epoxy compounds such as phthalic acid diglycidyl ester and triglycidyl isocyanurate, compounds having an epoxy group at the terminal of a silicone oil, and compounds having an alkoxysilane and an epoxy group.

From the viewpoints of reaction control and extrusion moldability, it is preferable that the epoxy compound is a diepoxy compound. Monoepoxy compounds do not have the effect of chain extension and are poor at imparting extrusion moldability. In addition, many of them have a low volatilization temperature, and gas during molding can be a problem. Furthermore, epoxy compounds with three or more functionalities can be effective in imparting melt viscosity, but it can be difficult to control the reaction and maintain fluidity.

As the epoxy compound, a bisphenol F diepoxy compound is preferred. Compared with other epoxy compounds, bisphenol F epoxy compounds have an excellent balance between epoxy equivalent and low volatility, so that they are less likely to cause problems such as decomposition gas and associated poor appearance while maintaining reactivity with the terminal functional groups of the polyester elastomer (A). Furthermore, for those that are liquid under normal temperature and pressure environments, they have the advantage of easily exhibiting bending fatigue while maintaining fluidity because they simultaneously exhibit a plasticizing effect while producing a chain extension effect, and it is preferable to use these compounds. As such epoxy compounds, Epicron 830 manufactured by DIC Corporation, jER4004P, jER4005P, jER4010P manufactured by Mitsubishi Chemical Corporation, etc. can be used.

The carbodiimide compound used in the present invention is a compound that has at least one carbodiimide group represented by (-N=C=N-) in the molecule and is capable of reacting with the terminal group of the polyester elastomer (A).

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, di-3,4-dichlorophenylcarbodiimide, di-2,5-dichlorophenylcarbodiimide, p-phenylene-bis-o-tolylcarbodiimide, p-phenylene-bis-dicyclohexylcarbodiimide, p-phenylene-bis-di-p-chlorophenylcarbodiimide, 2,6,2',6'-tetraisopropyldiphenylcarbodiimide, hexamethylene-bis-cyclohexylcarbodiimide Imide, ethylene-bis-diphenylcarbodiimide, ethylene-bis-di-cyclohexylcarbodiimide, N,N'-di-o-toluylcarbodiimide, N,N'-diphenylcarbodiimide, 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-phenyl-N'-toluylcarbodiimide, 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,N'-di-o-isopropylphenylcarbodiimide, N,N'-di-p-isopropylphenyl 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-triisopropyl mono- or di-carbodiimide compounds such as N,N'-di-2,4,6-triisobutylphenylcarbodiimide, poly(1,6-hexamethylenecarbodiimide), poly(4,4'-methylenebiscyclohexylcarbodiimide), poly(1,3-cyclohexylenecarbodiimide), poly(1,4-cyclohexylenecarbodiimide), poly(4,4'-diphenylmethanecarbodiimide), poly(3,3'-dimethyl-4, and polycarbodiimides such as poly(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 preferred are poly(1,6-hexamethylenecarbodiimide), poly(4,4'-methylenebiscyclohexylcarbodiimide), poly(1,3-cyclohexylenecarbodiimide), poly(1,4-cyclohexylenecarbodiimide), poly(4,4'-diphenylmethanecarbodiimide), and poly Examples of polycarbodiimides include 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, polycarbodiimides are preferred from the viewpoints of improving heat aging resistance and hydrolysis resistance, and reactivity with acid terminals, and particularly preferred are poly(1,4-cyclohexylenecarbodiimide) and poly(triisopropylphenylenecarbodiimide).

When the acid end blocking agent (C) is added, the content 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 the polyester elastomer (A) and the unmodified olefin-based elastomer (B). This component is added for the purpose of improving hydrolysis resistance and improving flex fatigue resistance by chain extension. If the content is less than 0.1 parts by mass, the improving effects are insufficient, while if the content exceeds 5 parts by mass, the flame retardancy may decrease and mechanical properties may decrease due to the foreign matter effect. Note that, when a high molecular weight polyester elastomer (A) that does not require chain extension is used as the polyester elastomer (A) or when a polyester elastomer (A) with a sufficiently small terminal acid value is used, the acid end blocking agent (C) may be 0 parts by mass.

[Epoxy group-containing polyolefin (D)]
The epoxy group-containing polyolefin (D) used in the present invention is a polyolefin resin modified with epoxy, and preferably has an epoxy value of 0.01 to 0.5 meq/g. The epoxy group-containing polyolefin (D), like the epoxy compound of the acid end-capping agent (C), reacts with the end group of the polyester elastomer (A) and acts as a compatibilizer that makes the polyester elastomer (A) and the unmodified olefin elastomer (D) compatible. In addition, the epoxy group-containing polyolefin (D) also contributes to stabilizing the melt viscosity during the melt retention of the resin composition due to its moderate epoxy value. 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 0.01 meq/g or less, the compatibility with the polyester elastomer (A) decreases, and the role of the compatibilizer is insufficient, which may cause pulsation during extrusion molding. If the epoxy value exceeds 0.5 meq/g, the melt viscosity increases during heat retention, and these gradually become coarse crosslinking points themselves, which may cause gelation.

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

When epoxy group-containing polyolefin (D) is added, the blending (content) amount 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, per 100 parts by mass of the total of polyester elastomer (A) and unmodified olefin-based elastomer (B). If the blending amount is less than 1 part by mass, it will not be effective as a compatibilizer, and if it exceeds 10 parts by mass, the acid terminals of polyester elastomer (A) will react with the epoxy groups during retention, which may cause gelation.

[Flame retardant]
In the polyester elastomer resin composition of the present invention, either a halogen-based flame retardant or a non-halogen-based flame retardant may be used as necessary.

[Brominated flame retardants (E)]
Examples of the halogen-based flame retardant used in the present invention include bromine-based flame retardants (E). Examples of the bromine-based flame retardant (E) include hexabromocyclododecane, decabromodiphenyl oxide, octabromodiphenyl oxide, tetrabromobisphenol A, bis(tribromophenoxy)ethane, bis(pentabromophenoxy)ethane, tetrabromobisphenol A epoxy resin, tetrabromobisphenol A carbonate, ethylene(bistetrabromophthalic)imide, ethylenebispentabromodiphenyl, tris(tribromophenoxy)triazine, bis(dibromopropyl)tetrabromobisphenol A, bis(dibromo Examples of suitable brominated polystyrenes include poly(dibromostyrene), poly(tribromostyrene), crosslinked brominated polystyrene, brominated crosslinked aromatic polymers, brominated epoxy resins, brominated phenoxy resins, brominated styrene-maleic anhydride polymers, tetrabromobisphenol S, tris(tribromoneopentyl)phosphate, polybromotrimethylphenylindane, and tris(dibromopropyl)isocyanurate. Among these, brominated polystyrene is preferred in terms of compatibility with the polyester elastomer (A).

[Flame retardant synergist (F)]
In the present invention, as the flame retardant synergist (F), an antimony oxide compound is preferably used. Examples of the antimony oxide compound include antimony trioxide, antimony pentoxide, and sodium antimonate.
The total content of the brominated flame retardant (E) and the flame retardant auxiliary (F) is preferably 5 to 30 parts by mass per 100 parts by mass of the polyester elastomer (A) and the unmodified olefin elastomer (B). By using the brominated flame retardant (E) and the flame retardant auxiliary (F) in such ranges, a polyester elastomer resin composition having particularly excellent flame retardancy can be prepared.

[Phosphorus-based flame retardants (G)]
Examples of non-halogen flame retardants that can be used in the present invention include phosphorus-based flame retardants.
Generally, phosphorus-based flame retardants include organic phosphorus compounds and inorganic phosphorus compounds. The phosphorus-based flame retardants (G) used in the present invention are roughly classified into organic phosphorus compounds and inorganic phosphorus compounds. Examples of organic phosphorus compounds include phosphates, phosphonates, phosphinates, and phosphites, and specifically, trimethyl phosphate, triethyl phosphate, tributyl phosphate, trioctyl phosphate, tributoxyethyl phosphate, octyl diphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, triphenyl phosphate, trixylenyl phosphate, tris-isopropylphenyl phosphate, diethyl-N,N-bis(2-hydroxyethyl)aminomethylphosphonate, and bis(1,3-phenylenediphenyl)phosphate. Among them, from the viewpoint of flame retardancy, metal phosphinates are preferred, and aluminum phosphinates are particularly preferred. Examples of inorganic phosphorus compounds include red phosphorus compounds and inorganic phosphate compounds such as ammonium (poly)phosphate, melamine (poly)phosphate, and piperazine (poly)phosphate.

As the phosphorus-based flame retardant (G), a phosphorus-based flame retardant having an average particle diameter D50 of 20 μm or less and a phosphorus concentration of 15 mass% or more can be used. Regarding the average particle diameter D50, if a large particle diameter is used, the surface smoothness of the extrusion molded product tends to deteriorate. Regarding the phosphorus concentration, a flame retardant with a low phosphorus concentration tends to have a poor flame retardant effect, so a large amount must be added, making it difficult to achieve both flame retardancy and other properties. The average particle diameter D50 is also called the median diameter, and can be measured and analyzed using a laser diffraction particle size distribution meter, and the phosphorus concentration can be measured (calculated) by ICP emission spectrometry. The average particle diameter D50 is preferably 16 μm or less, more preferably 12 μm or less. There is no particular restriction on the lower limit of the average particle diameter D50, but it is preferably 0.1 μm or more. The phosphorus concentration is preferably 18 mass% or more, more preferably 20 mass% or more. There is no particular restriction on the upper limit of the phosphorus concentration, but it is preferably 30 mass% or less.

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, further preferably 10 to 35 parts by mass, and particularly preferably 15 to 30 parts by mass, relative to 100 parts by mass of the total of the polyester elastomer (A) and the unmodified olefin elastomer (B). If the content of the phosphorus-based flame retardant (B) is less than 5 parts by mass, the flame retardancy is insufficient, whereas if the content exceeds 50 parts by mass, problems such as a decrease in mechanical properties arise.
The polyester elastomer resin composition of the present invention may contain a non-halogen flame retardant other than the phosphorus-based flame retardant as necessary. Examples of the non-halogen flame retardant other than the phosphorus-based flame retardant include nitrogen-based flame retardants, silicon-based flame retardants, metal hydroxides, and metal borates.

[Polyester elastomer resin composition]
The carboxyl group concentration in the polyester elastomer resin composition of the present invention is 10 eq/ton or less. The carboxyl group concentration is preferably 7 eq/ton or less, more preferably 5 eq/ton or less. It is also a preferred embodiment that the carboxyl group concentration in the polyester elastomer resin composition is 0 eq/ton. If the carboxyl group concentration exceeds 10 eq/ton, it is not preferred because the hydrolysis resistance is impaired.

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

Furthermore, when 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 salicylic acid-based light stabilizers can be used. Specifically, 2,2'-dihydroxy-4-methoxybenzophenone, 2-hydroxy-4-n-octoxybenzophenone, p-t-butylphenyl salicylate, 2,4-di-t-butylphenyl-3,5-di-t-butyl-4-hydroxybenzoate, 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-3',5'-di-t-amyl-phenyl)benzotriazole, 2-[2'-hydroxy-3',5'-bis(2 ... (α,α-dimethylbenzylphenyl)benzotriazole, 2-(2'-hydroxy-3'-t-butyl-5'-methylphenyl)-5-chlorobenazotriazole, 2-(2'-hydroxy-3',5'-di-t-butylphenyl)-5-chlorobenzothiazole, 2,5-bis-[5'-t-butylbenzoxazolyl-(2)]-thiophene, bis(3,5-di-t-butyl-4-hydroxybenzyl phosphate monoethyl ester)nickel salt, 2-ethoxy-5- 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'-hydroxy-5'-methyl-3'-(3'',4'',5' Examples of light stabilizers include 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.

The polyester elastomer resin composition of the present invention may contain various other additives. As additives, resins other than the polyester elastomer (A), inorganic fillers, stabilizers, and anti-aging agents may be added within a range that does not impair the characteristics of the present invention. In addition, other additives may be added, such as color pigments, inorganic and organic fillers, coupling agents, tackiness improvers, stabilizers such as quenchers and metal deactivators, 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 polyester elastomer (A), unmodified olefin elastomer (B), acid end-capping agent (C), and epoxy group-containing polyolefin resin (D) in total (acid end-capping agent (C) and epoxy group-containing polyolefin resin (D) are optional components).

The polyester elastomer resin composition obtained by the present invention has excellent acid resistance and hydrolysis resistance, and furthermore, is capable of retaining the inherent flexibility, moldability, chemical resistance, flex fatigue resistance, abrasion resistance, electrical properties, and other properties of polyester elastomers, and can therefore be used in a wide range of applications, such as various parts of electrical products, hoses, tubes, and cable coating materials. It is particularly useful for use in cable coatings. Furthermore, the polyester elastomer resin composition obtained by the present invention can be molded into various shapes by injection molding, transfer molding, blow molding, and other methods in addition to extrusion molding.

The following examples are provided to further explain the present invention, but the present invention is not limited to these examples. The measurements described in the examples were measured by the following methods.

[Melting point]
Using a differential scanning calorimeter "DSC220" manufactured by Seiko Denshi Kogyo Co., Ltd., 5 mg of the measurement sample was placed in an aluminum pan, the lid was pressed down to seal, and the sample was held at 250°C for 5 minutes to completely melt the sample, then quenched with liquid nitrogen, and then measured at a heating rate of 20°C/min from -150°C to 250°C. From the obtained thermogram curve, the endothermic peak temperature was taken as the melting point.

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

[Terminal acid value]
The terminal acid value (eq/t) of the polyester elastomer (A) was determined by a dissolution titration method 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 thereto, followed by titration with a 1/25 N ethanol solution of KOH.

The raw materials used in the examples are as follows.
[Polyester elastomer (A)]
(Polyester elastomers A-1, A-2, A-3, A-4)
Using dimethyl terephthalate, dimethyl naphthalate, 1,4-butanediol, and poly(tetramethylene oxide) glycol having a number average molecular weight of 1000 as raw materials, thermoplastic polyester elastomers A-1, A-2, A-3, and A-4 having the compositions shown in Table 1 were polymerized. The physical properties of each of the obtained polyester elastomers are shown in Table 1.

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

[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

[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

[Brominated flame retardants (E)]
(E-1) Brominated polystyrene: PDBS-80, manufactured by LANXESS KK [flame retardant synergist (F)]
(F-1) Antimony trioxide: Twinkling Star, manufactured by Chugoku Kogyo Co., Ltd.

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

Examples 1 to 10, Comparative Examples 1 to 5
The above raw materials were kneaded and pelletized in a twin-screw extruder in the ratios shown in Table 2. The pellets of the polyester elastomer resin composition were used to carry out the following evaluations. The results are shown in Table 2.

[Extrusion moldability (pulsation)]
The pellets melt-kneaded in the twin-screw extruder were extruded again from a round die in a single-screw extruder to extrude strands having a diameter of 3 mm. From this state, extrusion moldability was evaluated according to the following criteria.
◯: No fluctuation in discharge amount occurs, and extrusion properties are stable.
△: Stable when pulled at a constant speed using a take-up machine, but slight fluctuations in discharge rate are observed when allowed to hang down under its own weight.
×: The discharge amount fluctuated greatly and the product could not be taken over.
[Extrusion moldability (smoothness)]
The pellets melt-kneaded in the twin-screw extruder were extruded again from a T-die in a single-screw extruder to prepare a sheet product having a thickness of 0.2 mm. From the appearance of the sheet, the smoothness of the extrusion molded product was evaluated according to the following criteria.
◯: No roughness or bubbles were observed, and the sheet appearance and surface smoothness were good.
Δ: No sheet irregularities (melt fracture) or bubbles are observed, but uniform roughness like embossing is observed.
×: Sheet irregularities (melt fracture) and bubbles occurred, and the sheet appearance was poor.

[100°C Water Resistance Elongation Half-Life]
A JIS dumbbell-shaped No. 3 test piece was immersed in boiling water at 100° C. for a predetermined time, then removed and the tensile elongation at break was measured in accordance with JIS K6251: 2010. The test piece was prepared by injection molding a resin dried under reduced pressure at 100° C. for 8 hours into a 100 mm×100 mm×2 mm flat plate at a cylinder temperature (Tm+20° C.) and a mold temperature of 30° C. using an injection molding machine (manufactured by Yamashiro Seiki Co., Ltd., model-SAV), and then punching out a dumbbell-shaped No. 3 test piece from the flat plate.
The tensile elongation retention at break was calculated by the following formula, and the time at which this value reached 50% (tensile elongation half-life) was used as an index of hydrolysis resistance. The initial tensile elongation at break is the tensile elongation at break before the water resistance treatment.
Tensile elongation at break retention rate (%) = tensile elongation at break after water resistance treatment / initial tensile elongation at break × 100

[Acid resistance]
A 37% aqueous sulfuric acid solution was dropped onto a 3 mm thick flat molded product, which was then heat-treated at 90°C for 8 hours. Sulfuric acid was then dropped onto the same spot again, and heat-treated at 90°C for 16 hours. This cycle was counted as one cycle, and two cycles of treatment were performed in total. At the drop location, the molded product was carbonized by the sulfuric acid concentrated by the heat treatment, and the depth of the resulting erosion was measured from the cross section.

[Carboxyl group concentration]
The carboxyl group concentration (eq/t) of the polyester elastomer resin composition was determined by a dissolution titration method in which 200 mg of a thoroughly dried sample 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 thereto, followed by titration with a 1/25 N ethanol solution of KOH, in the same manner as in the case of the terminal acid value of the polyester elastomer (A).

As is clear from the results in Table 2, the polyester elastomer compositions of the present invention shown in Examples 1 to 10 have excellent acid resistance and hydrolysis resistance, while also being extrusion moldable. A comparison between Example 1 and Example 5 shows that the increase in the hard segment ratio in the polyester elastomer leads to a further improvement in acid resistance. A comparison between Example 1 and Example 2 shows that the increase in the amount of the acid end-capping agent (C) leads to a further improvement in hydrolysis resistance due to the reduction in the carboxyl group concentration. In Example 4, it can be seen that by using a polyester elastomer component with a low terminal acid value, high hydrolysis resistance can be achieved without adding the acid end-capping agent (C). A comparison between Example 1 and Example 6 shows that by using PBN as the hard segment in the polyester elastomer, acid resistance is reduced, but higher hydrolysis resistance can be achieved. In addition, in Example 10, a slight decrease in smoothness is observed, but this is not due to the combination of the formulation, and indicates that the particle size of the (G) component is large, resulting in some uniform roughness like embossing. On the other hand, the compositions of Comparative Examples 1 to 5, which do not satisfy the conditions of the present invention, are inferior to the compositions of the present invention in terms of extrusion moldability, acid resistance, and hydrolysis resistance.

In Comparative Example 1, where no acid end-capping agent (C) was added and the carboxyl group concentration was high, the hydrolysis resistance was poor. In Comparative Example 2, where no olefin-based elastomer (B) was added, the acid resistance was poor. On the other hand, in Comparative Example 3, where an excessive amount of olefin-based elastomer (B) was added, the acid resistance was good, but pulsation occurred during extrusion molding, and a decrease in extrusion moldability was observed. In Comparative Example 4, where the olefin-based elastomer (B) component was acid-modified, the surface smoothness of the extrusion molded product was impaired, and a decrease in extrusion moldability was also observed. This means that the acid-modified portion reacted with the acid end-capping agent, causing the generation of extremely high molecular weight components and gels, which caused a poor appearance of the extrusion molded product. Like Comparative Example 4, Comparative Example 5 contains an acid-modified olefin-based elastomer (B), but has good extrusion moldability because no acid end-capping agent (C) was used in combination. However, the addition of the acid-modified olefin-based elastomer (B) increases the carboxyl group concentration in the entire system, resulting in poor hydrolysis resistance.

As described above, the polyester elastomer resin composition of the present invention has excellent acid resistance and hydrolysis resistance, and also has good outer diameter stability and surface smoothness even when extruded. Therefore, it can be used in a wide range of applications, such as various parts of electrical products, hoses, tubes, and cable coating materials. 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 (9)

A polyester elastomer resin composition comprising a polyester elastomer (A) constituted by a hard segment made of a polyester having an aromatic dicarboxylic acid and an aliphatic and/or alicyclic diol as constituent components, and a soft segment made of an aliphatic polyether , and an unmodified olefin-based elastomer (B), in total 100 parts by mass, and comprising 60 to 70 parts by mass of the polyester elastomer (A) , 30 to 40 parts by mass of the unmodified olefin-based elastomer (B), and further comprising 0.1 to 5 parts by mass of an acid end-blocking agent (C) per 100 parts by mass of the total of the polyester elastomer (A) and the unmodified olefin-based elastomer (B),
the acid end-capping agent (C) is an epoxy compound and/or a carbodiimide compound;
the epoxy compound is a diepoxy compound,
The polyester elastomer resin composition has a carboxyl group concentration of 10 eq/ton or less. The polyester elastomer resin composition according to claim 1, further comprising 1 to 10 parts by mass of an epoxy group-containing polyolefin (D) per 100 parts by mass of the polyester elastomer (A) and the unmodified olefin-based elastomer (B) combined. 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 copolymerization component. The polyester elastomer resin composition according to any one of claims 1 to 3, wherein the soft segment in the polyester elastomer (A) is poly(tetramethylene oxide) glycol (PTMG) and/or ethylene oxide addition polymer of poly(propylene oxide) glycol (PPG-EO addition polymer). The polyester elastomer resin composition according to any one of claims 1 to 4, further comprising 5 to 30 parts by mass of a bromine-based flame retardant (E) and a flame retardant auxiliary (F) per 100 parts by mass of the polyester elastomer (A) and the unmodified olefin-based elastomer (B). The polyester elastomer resin composition according to any one of claims 1 to 4, further comprising 5 to 30 parts by mass of a phosphorus-based flame retardant (G) per 100 parts by mass of the polyester elastomer (A) and the unmodified olefin-based elastomer (B) combined. 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 mass% or more. The polyester elastomer resin composition according to any one of claims 1 to 7, which is used for cable coating. A cable coating material comprising the polyester elastomer resin composition according to any one of claims 1 to 7.