CN110546203B

CN110546203B - Polyester elastomer resin composition

Info

Publication number: CN110546203B
Application number: CN201880027528.4A
Authority: CN
Inventors: 赤石卓也; 前田祐欣; 森尾惠梨
Original assignee: Toyobo Co Ltd
Current assignee: Dongyang Textile Mc Co ltd
Priority date: 2017-04-27
Filing date: 2018-04-26
Publication date: 2021-07-30
Anticipated expiration: 2038-04-26
Also published as: JP6620893B2; CN110546203A; WO2018199239A1; JPWO2018199239A1

Abstract

A polyester elastomer resin composition which can improve the problems of mold fouling in long-term continuous use, and the reduction of the physical properties of a polyester elastomer caused by contact with grease in an environment at a temperature exceeding 140 ℃, wherein the thermoplastic polyester elastomer (A), the alicyclic polycarbodiimide compound and/or the aliphatic polycarbodiimide compound (B), the aromatic carbodiimide compound (C) and the polyamide resin (D) are contained in proportions of 0.1 to 2 parts by mass, (C)0.1 to 2 parts by mass and (D) 0.1 to 10 parts by mass, respectively, relative to 100 parts by mass of (A), the thermoplastic polyester elastomer (A) is a hard segment composed of a polyester containing an aromatic dicarboxylic acid and an aliphatic and/or alicyclic diol as constituent components, and at least 1 soft segment selected from the group consisting of aliphatic polyether, aliphatic polyester and aliphatic polycarbonate.

Description

Polyester elastomer resin composition

Technical Field

The present invention relates to a polyester elastomer resin composition which is excellent in heat resistance and grease resistance and is improved in mold fouling.

Background

Thermoplastic polyester elastomers are used for applications such as automobile parts, electric/electronic parts, fibers, and films as materials having excellent injection moldability and extrusion moldability, high mechanical strength, and excellent rubber properties such as elastic recovery, impact resistance, and flexibility, and excellent cold resistance.

Conventionally, thermoplastic polyester elastomers have been used as a method of thickening with polyepoxy compounds, polyisocyanate compounds, and the like, because of their low melt viscosity, and in recent years, they have been used in blow-molded products such as flexible boots (flexible boots) for the purpose of dust prevention of universal joints such as constant velocity joints of automobiles and the like, and retention of grease (grease), and the like, to exhibit the characteristics of thermoplastic polyester elastomers (see patent document 1).

As the properties required for functional members such as flexible boots, there are bending fatigue resistance, thermal aging resistance, oil resistance, grease resistance, etc., but there are increasing demands for further improvement thereof, and as a countermeasure, there are proposed an antioxidant combination (patent document 2), a combination of an antioxidant and an epoxy compound (patent document 3), a combination of an epoxy compound and a carbodiimide compound (patent document 4), and the like.

Although the methods of patent documents 2 and 3 certainly achieve the effect of improving heat aging resistance, oil resistance, grease resistance, and the like, particularly, grease resistance is not sufficient in terms of bending fatigue resistance and the like under a severe environment exceeding 140 ℃. In addition, in the method of patent document 4, a large amount of epoxy compound needs to be mixed, and the properties of the blow molded product such as oil resistance and grease resistance are not considered at all.

In order to solve the problems of the prior art, the applicant has proposed a polyester elastomer resin composition having excellent grease resistance even in a high-temperature environment (see patent document 5). However, although the method of patent document 5 is considered from the viewpoint of grease resistance, the problem of mold contamination during long-term continuous molding occurs, and there is still room for further improvement.

Documents of the prior art

Patent document

Patent document 1: japanese patent No. 3714747

Patent document 2: japanese laid-open patent publication No. 11-323109

Patent document 3: japanese laid-open patent publication No. 11-323110

Patent document 4: japanese patent laid-open No. 2012 and 107155

Patent document 5: PCT/JP2017/004502

Summary of the invention

Problems to be solved by the invention

The present invention has been made in view of the above-mentioned current state of the art, and an object of the present invention is to provide a polyester elastomer resin composition which is excellent in heat resistance and grease resistance under a high-temperature environment and is improved in mold fouling.

Means for solving the problems

In order to achieve the above object, the present inventors have conducted intensive studies on the improvement of grease resistance and the cause of mold contamination during long-term continuous molding. As a result, it has been found that when an alicyclic polycarbodiimide compound and/or an aliphatic polycarbodiimide compound are/is mixed as a thickener, improvement in grease resistance is observed when the amount of the polycarbodiimide compound is small, but heat resistance of the polyester elastomer resin composition cannot be satisfied. If the amount of the polycarbodiimide compound to be mixed is increased in order to overcome this deficiency, an isocyanate compound which is a decomposition product of the polycarbodiimide compound is generated during continuous molding over a long period of time, and the mold fouling property is remarkably deteriorated. Then, it was also found that: the present inventors have found that the content of the alicyclic polycarbodiimide compound and/or the aliphatic polycarbodiimide compound is limited to a specific range, and the alicyclic polycarbodiimide compound and/or the aliphatic polycarbodiimide compound are combined with the aromatic polycarbodiimide compound, whereby the generation of an isocyanate compound derived from the alicyclic polycarbodiimide compound and/or the aliphatic polycarbodiimide compound can be effectively suppressed, and the excellent lubricating grease resistance and heat resistance can be further exhibited, and finally completed the present invention.

That is, the present invention has the following configurations (1) to (7).

(1) A polyester elastomer resin composition characterized by comprising 100 parts by mass of (A) 0.1 to 2 parts by mass of (B), 0.1 to 2 parts by mass of (C), and 0.5 to 10 parts by mass of (D) a thermoplastic polyester elastomer (A) in which a hard segment composed of a polyester containing an aromatic dicarboxylic acid and an aliphatic and/or alicyclic diol as constituent components is bonded to at least 1 soft segment selected from the group consisting of an aliphatic polyether, an aliphatic polyester, and an aliphatic polycarbonate, an alicyclic polycarbodiimide compound and/or an aliphatic polycarbodiimide compound (B), an aromatic carbodiimide compound (C), and a polyamide resin (D).

(2) The polyester elastomer resin composition according to (1), wherein the alicyclic polycarbodiimide compound and/or the aliphatic polycarbodiimide compound (B) are mixed in an amount such that the amount of the carbodiimide functional group is 0.3 to 1.5 equivalents, when the amount of the terminal carboxyl group of the thermoplastic polyester elastomer (A) is 1.

(3) The polyester elastomer resin composition according to (1) or (2), wherein the polyamide resin (D) comprises polyamide 6 and/or a 2-or 3-or more-membered copolymerized polyamide resin.

(4) The polyester elastomer resin composition according to any one of (1) to (3), further comprising at least 1 antioxidant selected from an aromatic amine antioxidant, a hindered phenol antioxidant, a sulfur antioxidant and a phosphorus antioxidant, wherein the antioxidant is contained in an amount of 0.01 to 3 parts by mass per 100 parts by mass of the thermoplastic polyester elastomer (A).

(5) The polyester elastomer resin composition according to any one of (1) to (4), wherein the polyester elastomer resin composition has a reduced viscosity of 2.0 to 3.5dl/g and an acid value of 0 to 5 eq/t.

(6) The polyester elastomer resin composition according to any one of (1) to (5), wherein the reduced viscosity of the polyester elastomer resin composition after treatment at 130 ℃ for 300 hours in a state where a grease containing a urea compound is applied thereto is 2.0dl/g or more.

(7) The polyester elastomer resin composition according to any one of (1) to (6), wherein the soft segment of the thermoplastic polyester elastomer resin (A) is an aliphatic polyether.

Effects of the invention

The polyester elastomer resin composition of the present invention is excellent not only in heat resistance and grease resistance in a high-temperature environment but also in mold contamination during long-term continuous use and excellent in productivity, and therefore, is suitably used in applications requiring high levels of bending fatigue resistance, heat aging resistance, oil resistance, grease resistance and the like, even in a harsh environment exceeding 140 ℃.

Detailed Description

The polyester elastomer resin composition of the present invention is characterized by containing a thermoplastic polyester elastomer (a) in which a hard segment composed of a polyester containing an aromatic dicarboxylic acid and an aliphatic and/or alicyclic diol as constituent components and a soft segment composed of at least 1 selected from the group consisting of an aliphatic polyether, an aliphatic polyester and an aliphatic polycarbonate, an alicyclic polycarbodiimide compound and/or an aliphatic polycarbodiimide compound (B), an aromatic carbodiimide compound (C) and a polyamide resin (D) in specific proportions. This will be described in detail below.

[ thermoplastic polyester elastomer (A) ]

The thermoplastic polyester elastomer (a) used in the present invention is composed of a hard segment and a soft segment. The hard segment is composed of polyester. The aromatic dicarboxylic acid constituting the hard segment polyester may be any of the common aromatic dicarboxylic acids, and is not particularly limited, but terephthalic acid or naphthalenedicarboxylic acid (2, 6-naphthalenedicarboxylic acid is preferable among isomers) is preferable as the main aromatic dicarboxylic acid. The content of these aromatic dicarboxylic acids in the total dicarboxylic acids constituting the hard segment polyester is preferably 70 mol% or more, and more preferably 80 mol% or more. Examples of the other dicarboxylic acid component include aromatic dicarboxylic acids such as diphenyldicarboxylic acid, isophthalic acid, and sodium 5-sulfoisophthalate; alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid and tetrahydrophthalic anhydride; aliphatic dicarboxylic acids such as succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, dimer acid, and hydrogenated dimer acid. These may be used within a range not to lower the melting point of the resin to a large extent, and the amount thereof is 30 mol% or less, preferably 20 mol% or less based on the total acid components.

In the thermoplastic polyester elastomer (a) used in the present invention, general aliphatic or alicyclic diols can be widely used as the aliphatic or alicyclic diol constituting the hard segment polyester, and alkylene diols having 2 to 8 carbon atoms are mainly preferred without any particular limitation. Specific examples thereof include ethylene glycol, 1, 3-propanediol, 1, 4-butanediol, 1, 6-hexanediol, 1, 4-cyclohexanedimethanol, and the like. Among these, ethylene glycol and 1, 4-butanediol are preferable from the viewpoint of imparting heat resistance.

The hard segment polyester is more preferably a component composed of a butylene terephthalate unit (a unit composed of terephthalic acid and 1, 4-butanediol) or a butylene naphthalate unit (a unit composed of 2, 6-naphthalenedicarboxylic acid and 1, 4-butanediol), from the viewpoint of physical properties, moldability, and cost performance.

In addition, as the thermoplastic polyester elastomer (A) in the hard segment of the polyester, previously prepared suitable aromatic polyester, and then with soft segment component copolymerization, the aromatic polyester can be according to the common polyester manufacturing method easily obtained. Further, the polyester preferably has a number average molecular weight of 10000 to 40000.

The soft segment of the thermoplastic polyester elastomer (a) used in the present invention is selected from at least 1 of aliphatic polyether, aliphatic polyester and aliphatic polycarbonate.

Examples of the aliphatic polyether include poly (ethylene oxide) glycol, poly (propylene oxide) glycol, poly (tetramethylene ether) glycol, poly (hexamethylene ether) glycol, poly (trimethylene ether) glycol, a copolymer of ethylene oxide and propylene oxide, an ethylene oxide adduct of poly (propylene oxide) glycol, and a copolymer of ethylene oxide and tetrahydrofuran. Among them, poly (tetramethylene ether) glycol and an ethylene oxide adduct of poly (propylene oxide) glycol are preferable from the viewpoint of elastic properties.

Examples of the aliphatic polyester include poly (. epsilon. -caprolactone), polyheptalactone, polycaprylolactone, and polybutylene adipate. Among them, poly (. epsilon. -caprolactone) and polybutylene adipate are preferable from the viewpoint of elastic properties.

The aliphatic polycarbonate is preferably a component mainly composed of an aliphatic diol residue having 2 to 12 carbon atoms. Examples of the aliphatic diol include ethylene glycol, 1, 3-propanediol, 1, 4-butanediol, 1, 5-pentanediol, 1, 6-hexanediol, 1, 8-octanediol, 2-dimethyl-1, 3-propanediol, 3-methyl-1, 5-pentanediol, 2, 4-diethyl-1, 5-pentanediol, 1, 9-nonanediol, and 2-methyl-1, 8-octanediol. In particular, the aliphatic diol having 5 to 12 carbon atoms is preferable from the viewpoint of flexibility and low-temperature characteristics of the obtained thermoplastic polyester elastomer. These components may be used alone in 1 kind or in combination of 2 or more kinds as necessary, based on the matters described below.

The aliphatic polycarbonate diol having a soft segment constituting the thermoplastic polyester elastomer (a) used in the present invention and good low-temperature characteristics is preferably one having a low melting point (for example, 70 ℃ or lower) and a low glass transition temperature. In general, an aliphatic polycarbonate diol comprising 1, 6-hexanediol used for forming a soft segment of a thermoplastic polyester elastomer has a low glass transition temperature of about-60 ℃ and a melting point of about 50 ℃, and thus has good low-temperature characteristics. In addition, the aliphatic polycarbonate diol obtained by copolymerizing an appropriate amount of, for example, 3-methyl-1, 5-pentanediol with the above aliphatic polycarbonate diol has a slightly higher glass transition point than the original aliphatic polycarbonate diol, but has a lower melting point or is amorphous, and thus corresponds to an aliphatic polycarbonate diol having good low-temperature characteristics. In addition, for example, the melting point of an aliphatic polycarbonate diol comprising 1, 9-nonanediol and 2-methyl-1, 8-octanediol is about 30 ℃ and the glass transition temperature is about-70 ℃, which is very low, and therefore, the aliphatic polycarbonate diol is equivalent to an aliphatic polycarbonate diol having good low-temperature characteristics.

As the soft segment of the thermoplastic polyester elastomer (a) used in the present invention, an aliphatic polyether is preferable from the viewpoint of solving the problem of the present invention.

The thermoplastic polyester elastomer (a) used in the present invention is preferably a copolymer containing terephthalic acid, 1, 4-butanediol and poly (tetramethylene ether) glycol as main components. Among the dicarboxylic acid components constituting the thermoplastic polyester elastomer (a), terephthalic acid is preferably at least 40 mol%, more preferably at least 70 mol%, still more preferably at least 80 mol%, and particularly preferably at least 90 mol%. In the diol component constituting the thermoplastic polyester elastomer (a), the total amount of 1, 4-butanediol and poly (tetramethylene ether) glycol is preferably 40 mol% or more, more preferably 70 mol% or more, still more preferably 80 mol% or more, and particularly preferably 90 mol% or more.

The number average molecular weight of the poly (tetramethylene ether) glycol is preferably 500 to 4000. When the number average molecular weight is less than 500, the elastomer properties are not easily exhibited. On the other hand, when the number average molecular weight exceeds 4000, the compatibility with the hard segment component may be lowered, and the block-like copolymerization may be difficult. The number average molecular weight of the poly (tetramethylene ether) glycol is more preferably 800 to 3000 inclusive, and still more preferably 1000 to 2500 inclusive.

In the thermoplastic polyester elastomer (a) used in the present invention, the mass ratio of the hard segment to the soft segment is generally preferably the hard segment: soft segment 30: 70-95: 5, more preferably 40: 60-90: 10, further preferably 45: 55-87: 13, most preferably 50: 50-85: 15, or more.

The thermoplastic polyester elastomer (a) used in the present invention can be produced by a known method. For example, any of the following methods may be used: a method in which a lower alcohol diester of a dicarboxylic acid, an excess amount of a low-molecular-weight diol, and a soft segment component are subjected to transesterification in the presence of a catalyst to thereby polycondense the obtained reaction product; a method in which a dicarboxylic acid, an excessive diol and a soft segment component are subjected to an esterification reaction in the presence of a catalyst to thereby obtain a reaction product, and the reaction product is subjected to polycondensation; a method of making a hard segment polyester in advance, adding a soft segment component thereto, and randomizing the same by transesterification; a method of linking the hard segment to the soft segment by a linker; further, when poly (. epsilon. -caprolactone) is used as the soft segment, a method of causing addition reaction of the hard segment with the. epsilon. -caprolactone monomer, and the like can be used.

[ alicyclic polycarbodiimide Compound and/or aliphatic polycarbodiimide Compound (B) ]

In the present invention, even if the compound has an aromatic ring, the compound directly bonded to the carbodiimide group is an aliphatic and/or alicyclic group, and is an alicyclic polycarbodiimide compound and/or an aliphatic polycarbodiimide compound (B). The alicyclic polycarbodiimide compound and/or the aliphatic polycarbodiimide compound (B) used in the present invention have a function as a thickener. The alicyclic polycarbodiimide compound and/or the aliphatic polycarbodiimide compound (B) used in the present invention may be a polycarbodiimide composed of an alicyclic and/or aliphatic compound and having 2 or more carbodiimide groups (-N ═ C ═ N-structure) in 1 molecule.

The alicyclic polycarbodiimide compound and/or the aliphatic polycarbodiimide compound (B) used in the present invention can be obtained, for example, by decarboxylation reaction (elimination of carbon dioxide) of a diisocyanate compound. Examples of the diisocyanate compound that can be used here include hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, cyclohexane-1, 4-diisocyanate, xylylene diisocyanate, isophorone diisocyanate, methylcyclohexane diisocyanate, and tetramethylxylylene diisocyanate. These may be used alone in 1 kind, or may be copolymerized in 2 or more kinds. In addition, a branched structure may be introduced, or a functional group other than a carbodiimide group and an isocyanate group may be introduced by copolymerization. Further, the terminal isocyanate may be used as it is, or the polymerization degree may be controlled by reacting the terminal isocyanate, or a part of the terminal isocyanate may be blocked.

The alicyclic polycarbodiimide compound and/or the aliphatic polycarbodiimide compound (B) used in the present invention are preferably alicyclic polycarbodiimides derived from dicyclohexylmethane diisocyanate, cyclohexane-1, 4-diisocyanate, isophorone diisocyanate, and the like, and particularly preferably polycarbodiimides derived from dicyclohexylmethane diisocyanate and isophorone diisocyanate.

From the viewpoint of stability and handling properties, it is preferable that the alicyclic polycarbodiimide compound and/or the aliphatic polycarbodiimide compound (B) used in the present invention contain 2 to 50 carbodiimide groups per molecule. More preferably, the carbodiimide group contains 5 to 30 carbodiimide groups per molecule. In the case of a polycarbodiimide obtained from a diisocyanate compound, the number of carbodiimides (i.e., the number of carbodiimide groups) in the polycarbodiimide molecule corresponds to the degree of polymerization. For example, the polycarbodiimide obtained by linking 21 diisocyanate compounds in a chain has a polymerization degree of 20 and the number of carbodiimide groups in the molecular chain is 20. Typically, the polycarbodiimide compound is a mixture of molecules of various lengths, the number of carbodiimide groups being expressed as an average value. The carbodiimide group number having the above range is preferably in view of uniform reactivity and bleed resistance because it can be powdered if it is solid at around room temperature, and therefore workability and compatibility when it is mixed with the thermoplastic polyester elastomer (a) are excellent. The number of carbodiimide groups can be measured, for example, by a usual method (a method of dissolving an amine and then performing back titration with hydrochloric acid).

From the viewpoint of stability and handling properties, it is preferable that the alicyclic polycarbodiimide compound and/or the aliphatic polycarbodiimide compound (B) used in the present invention have an isocyanate group at an end, and the content of the isocyanate group is 0.5 to 4% by mass. More preferably, the content of isocyanate groups is 1 to 3% by mass. Particularly, polycarbodiimide derived from dicyclohexylmethane diisocyanate or isophorone diisocyanate and having an isocyanate group content within the above range is preferable. The content of isocyanate groups can be measured by a usual method (a method of dissolving an amine and then carrying out back titration with hydrochloric acid).

The content of the alicyclic polycarbodiimide compound and/or the aliphatic polycarbodiimide compound (B) used in the present invention is 0.1 to 2 parts by mass, preferably 0.3 to 1.8 parts by mass, more preferably 0.5 to 1.5 parts by mass, per 100 parts by mass of the thermoplastic polyester elastomer (a). When the content of the alicyclic polycarbodiimide compound and/or the aliphatic polycarbodiimide compound (B) is less than the above range, the heat resistance tends to be insufficient, and when the content exceeds the above range, hydrolysis of the thermoplastic polyester elastomer (a) tends to occur due to the basicity of the polycarbodiimide compound, thereby affecting the mechanical properties, and further, when the continuous molding is continued for a long period of time, an isocyanate compound which is a decomposition product of the polycarbodiimide compound is generated, thereby deteriorating the mold fouling property.

When the amount of the terminal carboxyl group of the thermoplastic polyester elastomer (A) is 1, the mixing ratio of the alicyclic polycarbodiimide compound and/or the aliphatic polycarbodiimide compound (B) used in the present invention is preferably such that the amount of the carbodiimide functional group is 0.3 to 1.5 equivalents. The amount of the alicyclic/aliphatic carbodiimide functional group is 0.3 to 1.5 equivalents of the amount of the alicyclic polycarbodiimide compound and/or the aliphatic polycarbodiimide compound (B) contained in the polyester elastomer resin composition, when 1 equivalent of the amount of the terminal carboxyl group of the thermoplastic polyester elastomer (A) contained in the polyester elastomer resin composition is taken. The amount of the alicyclic/aliphatic carbodiimide functional group is more preferably 0.5 equivalent to 1.3 equivalents, and still more preferably 0.8 equivalent to 1.1 equivalents. When the carbodiimide functional group content is less than the above range, the heat resistance of the intended thermoplastic polyester elastomer (a) may be insufficient, and when it exceeds the above range, an excessive amount of the polycarbodiimide may be decomposed during molding to generate a large amount of an isocyanate compound which becomes a mold-staining component, thereby significantly deteriorating the mold-staining property.

[ aromatic carbodiimide Compound (C) ]

In the present invention, a compound in which an aromatic ring is directly bonded to a carbodiimide group is used as the aromatic carbodiimide compound (C). The aromatic carbodiimide compound (C) used in the present invention functions as a chain-blocking agent for the acid terminals of the molecular chain of the thermoplastic polyester elastomer (a). Further, the alicyclic polycarbodiimide compound and/or the aliphatic polycarbodiimide compound (B) are contained in predetermined amounts, respectively, and thereby the effects of suppressing mold contamination during long-term continuous molding and achieving excellent grease resistance and heat resistance are achieved. Consider that: the aromatic isocyanate compound which is a decomposition product of the aromatic carbodiimide compound (C) is easily deactivated, and therefore, even if it is generated, it is difficult to cause mold contamination. The aromatic carbodiimide compound (C) used in the present invention may be a carbodiimide composed of an aromatic compound and having 1 or more carbodiimide groups (-N ═ C ═ N-structure) in a molecule.

The aromatic carbodiimide compound (C) used in the present invention can be synthesized by subjecting various organic (di) isocyanates to decarboxylation condensation reaction using, for example, an organophosphorus compound or an organometallic compound as a catalyst.

As the organic isocyanate which becomes a raw material for producing the aromatic carbodiimide, for example, 2, 6-diisopropylbenzene isocyanate can be used.

As the organic diisocyanate to be used as a raw material for producing the aromatic carbodiimide, 1 or 2 or more selected from 1, 5-naphthalene diisocyanate, 4 ' -diphenylmethane diisocyanate, 4 ' -diphenyldimethylmethane diisocyanate, 1, 3-phenylene diisocyanate, 1, 4-phenylene diisocyanate, 2, 4-toluene diisocyanate, 2, 6-toluene diisocyanate, 3 ', 5,5 ' -tetraisopropylbiphenyl-4, 4 ' -diisocyanate, and 1,3, 5-triisopropylbenzene-2, 4-diisocyanate can be used.

Among them, 1,3, 5-triisopropylbenzene-2, 4-diisocyanate is preferable from the viewpoint of high stability and imparting excellent hydrolysis resistance to the polyester elastomer resin composition.

The content of the aromatic carbodiimide compound (C) used in the present invention is 0.1 to 2 parts by mass, preferably 0.2 part by mass or more and 1.5 parts by mass or less, and more preferably 0.3 part by mass or more and 1 part by mass or less, with respect to 100 parts by mass of the thermoplastic polyester elastomer (a). When the content of the aromatic carbodiimide compound (C) is less than the above range, the above-mentioned effects cannot be obtained, and when it exceeds the above range, hydrolysis of the thermoplastic polyester elastomer (A) may occur due to the basicity of the polycarbodiimide compound, thereby affecting the mechanical properties; the working environment may be deteriorated due to the odor characteristic of the aromatic carbodiimide.

[ Polyamide resin (D) ]

The polyamide resin (D) used in the present invention has an effect of improving the heat aging resistance of the polyester elastomer. The polyamide resin (D) used in the present invention is a polymer compound having an amide bond in the molecular chain, and includes: a polyamide obtained from a diamine having an aliphatic hydrocarbon group having 2 to 20 carbon atoms or a substituted aliphatic hydrocarbon group thereof, or an aromatic hydrocarbon group having 6 to 16 carbon atoms or a substituted aromatic hydrocarbon group thereof, and a dicarboxylic acid having an aliphatic hydrocarbon group having 2 to 20 carbon atoms or a substituted aliphatic hydrocarbon group thereof, or an aromatic hydrocarbon group having 6 to 16 carbon atoms or a substituted aromatic hydrocarbon group thereof; polymers derived from lactams; polymers derived from omega-aminocarboxylic acids, and the like. Examples thereof include polymers of salts obtained by reacting adipic acid, sebacic acid, linoleic acid, dodecanedioic acid, etc. with ethylenediamine, hexamethylenediamine, m-xylylenediamine, etc., and copolymers thereof or combinations of 2 or more thereof may be used. Specifically, there may be mentioned: polyamide 4, polyamide 6, polyamide 7, polyamide 8, polyamide 9, polyamide 11, polyamide 12 obtained from a lactam or an ω -aminocarboxylic acid; polyamide 66, polyamide 69, polyamide 610, polyamide 611, polyamide 612, polyamide 6T, polyamide 6I, polyamide MXD6 obtained from a diamine and a dicarboxylic acid; examples of the copolymer include polyamide 6/66, polyamide 6/610, polyamide 6/6T, polyamide 6I/6T, and polyamide 6/66/12. Among these polyamide resins, polyamide 6 and/or a copolymerized polyamide resin of 2-or 3-or more-membered can exhibit excellent effects. The polyamide resin (D) is more preferably a 2-or 3-or more-membered copolymerized polyamide resin.

The amine value of the polyamide resin (D) used in the present invention is preferably 50 to 2000 eq/t. When the amine value is less than 50eq/t, the effect of trapping the isocyanate compound which is a decomposition product of polycarbodiimide as a mold-staining component is weak. When the amine value is more than 2000eq/t, the thermoplastic polyester elastomer (A) may be hydrolyzed to affect the mechanical properties. The amine value is preferably 70 to 1000eq/t, more preferably 100 to 700eq/t, and still more preferably 100 to 550 eq/t.

The polyamide resin (D) used in the present invention is contained in an amount of 0.5 to 10 parts by mass per 100 parts by mass of the thermoplastic polyester elastomer (A). When the amount of the polyamide resin (D) is more than the above range, the inherent properties of the thermoplastic polyester elastomer (A) may be impaired, and when the amount is less than the above range, the effect of improving heat resistance is small. The content of the polyamide resin (D) is preferably 1 to 7 parts by mass, more preferably 2 to 5 parts by mass, per 100 parts by mass of the thermoplastic polyester elastomer (a).

[ polyester elastomer resin composition ]

The reduced viscosity of the polyester elastomer resin composition of the present invention is preferably 2.0 to 3.5 dl/g. More preferably 2.1 to 3.0dl/g, still more preferably 2.2 to 2.9 dl/g. When the reduced viscosity is less than the above range, the heat aging resistance as a resin composition is insufficient, and the intended grease resistance tends not to be obtained. When the reduced viscosity is more than the above range, the molded article tends to have poor appearance, such as molding processability, particularly flow marks at the time of injection molding.

The acid value of the polyester elastomer resin composition of the present invention is preferably 0 to 5 eq/t. When the acid value is more than 5eq/t, hydrolysis tends to occur due to the action of the urea compound in the grease under a high-temperature environment of 130 ℃ or higher, thereby significantly deteriorating mechanical properties.

The method of using the thickener is simple and convenient for the purpose of making the acid value and reduced viscosity of the polyester elastomer resin composition fall within the above ranges, but is not limited to this method, and for example, a solid-phase polymerization method may be employed. The solid phase polymerization can be carried out by a known method, and for example, a method of increasing the viscosity by allowing the pellets to stand or flow while the polycondensation reaction is carried out at a temperature 20 to 40 ℃ lower than the melting point of the thermoplastic polyester elastomer under the flow of an inert gas or under reduced pressure.

In the resin composition of the present invention, a general-purpose antioxidant such as an aromatic amine-based, hindered phenol-based, phosphorus-based, or sulfur-based antioxidant is preferably blended. They may be used in combination of 2 or more. Specific examples of the aromatic amine antioxidant used in the resin composition of the present invention include phenylnaphthylamine, 4 '-dimethoxydiphenylamine, 4' -bis (. alpha.,. alpha. -dimethylbenzyl) diphenylamine and 4-isopropoxydiphenylamine.

As the hindered phenol antioxidant, a general-purpose compound can be used, but a compound having a molecular weight of 500 or more, such as N, N' -hexamethylene-bis (3, 5-di-t-butyl-4-hydroxyhydrocinnamamide) and tetrakis [ methylene-3- (3, 5-di-t-butyl-4-hydroxyphenyl) propionate ] methane, is preferable from the viewpoint of being difficult to volatilize in a high-temperature atmosphere.

Examples of the phosphorus-containing antioxidant include phosphorus-containing compounds such as phosphoric acid, phosphorous acid, hypophosphorous acid derivatives, phenylphosphonic acid, polyphosphonate esters, and diphosphite ester compounds. Specific examples thereof include triphenyl phosphite, diphenyldecyl phosphite, phenyldiisodecyl phosphite, tris (nonylphenyl) phosphite, bis (2, 4-di-t-butylphenyl) pentaerythritol diphosphite, bis (2, 6-di-t-butyl-4-methylphenyl) pentaerythritol diphosphite and the like.

Examples of the sulfur-based antioxidant include sulfur-containing compounds such as thioether-based, dithionate-based, mercaptobenzimidazole-based, thiodiphenylthiourea-based, and thiodipropionate-based compounds. Specific examples thereof include dilauryl thiodipropionate, distearyl thiodipropionate, didodecyl thiodipropionate, ditetradecyl thiodipropionate, dioctadecyl thiodipropionate, pentaerythritol tetrakis (3-dodecylthiopropionate), thiobis (N-phenyl-. beta. -naphthylamine), 2-mercaptobenzothiazole, 2-mercaptobenzimidazole, tetramethylthiuram monosulfide, tetramethylthiuram disulfide, nickel dibutyldithiocarbamate, nickel isopropylxanthate, and trilauryl trithiophosphite. In particular, a thioether-based antioxidant having a thioether structure can be suitably used because it receives oxygen from an oxidized substance and reduces it.

The amount of each antioxidant is preferably 0.01 to 3 parts by mass, more preferably 0.05 to 2 parts by mass, and still more preferably 0.1 to 1 part by mass, per 100 parts by mass of the thermoplastic polyester elastomer (A).

As a method for determining the composition and composition ratio of the polyester elastomer resin composition used in the present invention, the composition may be determined by dissolving a sample in a solvent such as deuterated chloroform and measuring¹The proton integral ratio of H-NMR was thus calculated.

Further, when weather resistance is required for the 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. The amount of addition is preferably 0.1% to 5% by mass of the resin composition.

Other various additives may be mixed in the polyester elastomer resin composition of the present invention. As the additive, a resin other than the above, an inorganic filler, a stabilizer and an antioxidant may be added within a range not impairing the characteristics of the present invention. As other additives, a coloring pigment, an inorganic filler, an organic filler, a coupling agent, a viscosity improver, a quencher, a stabilizer such as a metal deactivator, a flame retardant, and the like may be added. The total amount of these various additives is preferably 20 parts by mass or less, and more preferably 10 parts by mass or less, based on 100 parts by mass of the thermoplastic polyester elastomer (a).

In the polyester elastomer resin composition of the present invention, the total of the thermoplastic polyester elastomer (a), the alicyclic polycarbodiimide compound and/or the aliphatic polycarbodiimide compound (B), the aromatic carbodiimide compound (C), and the polyamide resin (D) is preferably 70% by mass or more of the entire composition, more preferably 80% by mass or more of the entire composition, and still more preferably 90% by mass or more of the entire composition.

The polyester elastomer resin composition of the present invention is constituted as described above, and therefore has the following features: the reduced viscosity after treatment for 300 hours at 130 ℃ in the evaluation of grease resistance described in the examples described later was 2.0dl/g or more.

Further, the polyester elastomer resin composition of the present invention is constituted as described above, and therefore has the following features: in a heat aging test for evaluating grease resistance described in examples described later, the tensile elongation after heat treatment at 140 ℃ for 300 hours is 200% or more. As described in examples, the tensile elongation is in accordance with JIS K6251: elongation at break measured at 2010.

Further, the polyester elastomer resin composition of the present invention is constituted as described above, and therefore has the following features: in the bending fatigue test for evaluating grease resistance described in the examples described later, the number of demattia fractures (the number of times until fracture) in an atmosphere at 130 ℃ is 400 ten thousand or more.

The polyester elastomer resin composition of the present invention is constituted as described above, and therefore has the following features: in a heat aging test for evaluating grease resistance described in examples described later, the tensile elongation after heat treatment at 150 ℃ for 500 hours is 500% or more. As described in examples, the tensile elongation is in accordance with JIS K6251: elongation at break measured at 2010.

Examples

The following examples are given to demonstrate the effects of the present invention, but the present invention is not limited to these examples. The measurement values described in the examples were measured by the following methods.

Melting point:

a differential scanning calorimeter "DSC 220 type" manufactured by japanese fine electronics was used. Specifically, 5mg of a measurement sample was placed in an aluminum pan, the aluminum pan was covered with a lid, the aluminum pan was sealed, and the measurement sample was melted in nitrogen at 250 ℃ for 2 minutes, and then cooled to 50 ℃ at a cooling rate of 20 ℃/minute, and further heated from 50 ℃ to 250 ℃ at 20 ℃/minute, and a thermogram curve was measured. From the obtained thermogram, the endothermic peak of melting was obtained as a melting point.

Reduced viscosity (dl/g):

0.02g of the fully dried polyester elastomer resin composition was dissolved in 10ml of a mixed solvent of phenol/tetrachloroethane (mass ratio 6/4), and the reduced viscosity was measured at 30 ℃ with an Ubbelohde viscometer.

Acid value (eq/t):

0.2g of the sample was weighed out accurately, dissolved in 20ml of chloroform, and titrated with 0.01N potassium hydroxide (ethanol solution) to obtain an acid value. Phenolphthalein was used as an indicator.

Amine number (eq/t):

a3 g sample was weighed and dissolved in 80ml of m-cresol to prepare a solution. The solution was titrated by potentiometric titration using "AT-500N" manufactured by Kyoto electronics industries, Ltd and 0.05mol/l of a perchloromethane solution as a titration solution to obtain an amine value.

Relative viscosity:

in general, the relative viscosity of the polyamide resin is measured by a method based on three solvents of m-cresol, 96% sulfuric acid and 90% formic acid depending on the kind of solvent used for dissolution, but in the present invention, the relative viscosity of the polyamide resin (C) is measured using a 98% sulfuric acid solution (polyamide resin concentration 1g/dl, temperature 25 ℃).

The raw materials used in the examples are as follows.

Thermoplastic polyester elastomer (a):

(polyester elastomer A1)

According to the method described in Japanese patent application laid-open No. 9-59491, a thermoplastic polyester elastomer having 100/88/12 (molar ratio) of terephthalic acid/1, 4-butanediol/polyoxytetramethylene glycol (PTMG: number average molecular weight 1500) was produced as polyester elastomer A1.

The polyester elastomer A1 had a melting point of 197 ℃, a reduced viscosity of 1.86dl/g and an acid value of 38 eq/t.

(polyester elastomer A2)

According to the method described in Japanese patent application laid-open No. 9-59491, a thermoplastic polyester elastomer having 100/90/10 (molar ratio) of terephthalic acid/1, 4-butanediol/polyoxytetramethylene glycol (PTMG: number average molecular weight 2000) was produced as polyester elastomer A2.

The polyester elastomer A2 had a melting point of 205 ℃, a reduced viscosity of 2.15dl/g and an acid value of 35 eq/t.

(polyester elastomer A3)

The polyester elastomer A1 was treated at 190 ℃ for 20 hours in a vacuum state to obtain a polyester elastomer A3.

The polyester elastomer A3 had a melting point of 201 ℃, a reduced viscosity of 2.86dl/g and an acid value of 21 eq/t.

Alicyclic polycarbodiimide compound and/or aliphatic polycarbodiimide compound (B):

alicyclic polycarbodiimide compound (B1): CARBODILITE LA-1 (manufactured by Nisshin Kagaku K.K., carbodiimide value: 4050eq/t)

Alicyclic polycarbodiimide compound (B2): CARBODILITE HMV-15CA (available from Nisshin Kabushiki Co., Ltd., carbodiimide value: 3820eq/t)

Aromatic carbodiimide compound (C):

aromatic carbodiimide compound (C1): stabaxol 1LF (number average molecular weight 360, manufactured by Langsheng Co.)

Aromatic carbodiimide compound (C2): stabaxol P (number average molecular weight 3500, manufactured by Langsheng Co.)

Aromatic carbodiimide compound (C3): stabaxol P100 (number average molecular weight 10000, manufactured by Langsheng Co.)

Polyamide resin (D):

polyamide 6/66/12 (relative viscosity 1.3, amine number 490eq/t)

[ other additives ]

Releasing agent:

licowax E (manufactured by Kelaien corporation)

Aromatic amine antioxidant:

nonflex DCD (produced by Dai-Innovation chemical Co., Ltd.) (4, 4' -bis (. alpha.,. alpha. -dimethylbenzyl) diphenylamine)

Hindered phenol-based antioxidant:

irganox1010 (manufactured by BASF corporation)

Hindered phenol-based antioxidant:

irganox1098 (manufactured by BASF corporation)

Sulfur-based antioxidant:

lasumit LG (first Industrial pharmaceutical Co., Ltd.) (dilauryl thiodipropionate)

Examples 1 to 7 and comparative examples 1 to 5

According to the formulation composition shown in table 1, various additives were added to 100 parts by mass of the thermoplastic polyester elastomer, and the resulting mixture was melt-kneaded at 240 ℃ using a twin-screw extruder, and then pelletized to obtain pellets of examples 1 to 7 and comparative examples 1 to 5. Using these pellets, the following evaluations were carried out. The results are shown in Table 1.

< method for testing grease resistance >

Grease containing a urea compound (Raremax SLF) was used as a thickener, and the evaluation was performed by the following flexural fatigue test, tensile test after heat aging, and reduced viscosity measurement.

[ bending fatigue test ]

The flexural fatigue resistance was evaluated by repeating bending at a speed of 300 cycles/minute and a collet pitch of 75mm and 19mm in an atmosphere of 130 ℃ until the occurrence of fracture with respect to a test piece specified below using a Demantia (De Mattia) flexural fracture Tester BE-102 (manufactured by Tester industries, Ltd.). As the test piece, an injection-molded article (20 mm in width, 100mm in length, 3.6mm in thickness, 20mm in width at the center in the longitudinal direction and having R2.4 grooves as a whole) prepared at a cylinder temperature of 240 ℃ and a mold temperature of 50 ℃ was used. In order to confirm grease resistance, the test piece was tested in a state in which the rear surface of the groove portion of R2.4 was uniformly coated with grease 3 g.

[ tensile test after Heat aging ]

A test piece was prepared by punching a dumbbell shape according to JIS3 in a direction perpendicular to the flow direction of the resin of an injection-molded article (width 100mm, length 100mm, thickness 2.0mm) prepared at a cylinder temperature of 240 ℃ and a mold temperature of 50 ℃. The test piece was annealed (annealed) by a hot air dryer at 140 ℃ for 300 hours in a state where 3g of grease was uniformly applied to one surface thereof, and thereafter, the surface was treated in accordance with JIS K6251: 2010 tensile elongation (elongation at break) was measured.

[ measurement of reduced viscosity after Heat aging ]

A test piece of an injection-molded article (width 100mm, length 100mm, thickness 2.0mm) prepared at a cylinder temperature of 240 ℃ and a mold temperature of 50 ℃ was used. After annealing treatment was performed for 300 hours using a hot air dryer at 130 ℃ in a state where 10g of grease was uniformly applied to one surface of the test piece, the reduced viscosity was measured according to the method for measuring the reduced viscosity of the polyester elastomer resin composition described above.

< test method for evaluating Heat resistance >

A test piece was prepared by punching a dumbbell shape according to JIS3 in a direction perpendicular to the flow direction of the resin of an injection-molded article (width 100mm, length 100mm, thickness 2.0mm) prepared at a cylinder temperature of 240 ℃ and a mold temperature of 50 ℃. After annealing treatment for 500 hours using a hot air dryer at 150 ℃, the resultant was annealed according to JIS K6251: 2010 tensile elongation (elongation at break) was measured.

< test method for evaluating mold contamination >

The molded article was molded by an electric injection molding machine EC-100N (manufactured by Toshiba molding machine) at a cylinder temperature of 300 ℃ and a mold temperature of 50 ℃ for 8 seconds, cooled for 10 seconds, and molded by a mold (material STVAX) of 100X 1mmt, and evaluated according to the following criteria.

X: attachment to the mold occurs in less than 500 shots (shots).

O: there was no sticking to the mold even above 500 injections.

Here, attaching to the mold means: after injection molding, the molded article is stuck to the fixed side, and the molded article cannot be automatically taken out. The number of injections shown in table 1 is (500) when 500 injections were not given, and when less than 500 injections were given, the number of injections was indicated.

As is clear from table 1: any of examples 1 to 7 within the scope of the present invention was excellent in grease resistance, heat resistance and mold fouling resistance. In contrast, comparative example 1, which contained no aromatic carbodiimide, had poor grease resistance (reduced specific viscosity) and heat resistance. The mold staining property of comparative example 2, which contains too much alicyclic polycarbodiimide compound, was remarkably poor. Comparative example 3, which did not contain an alicyclic/aliphatic polycarbodiimide compound, was inferior in grease resistance and heat resistance. Comparative example 4, in which the content of the polyamide compound was too small, was inferior in grease resistance and heat resistance. Comparative example 5, in which the content of the aromatic carbodiimide compound was too large, was inferior in grease resistance and heat resistance, and further, the odor properties, which were not problematic in each example and the other comparative examples, were also problematic.

Industrial applicability of the invention

The polyester elastomer resin composition of the present invention is excellent not only in grease resistance under high temperature environment, but also in mold contamination resistance even when used continuously for a long period of time, and is excellent in productivity, and therefore, a molded article can be obtained which can be used under severe environment of over 140 ℃ even in applications where bending fatigue resistance, thermal aging resistance, oil resistance, grease resistance, and the like are required at high levels.

Claims

1. A polyester elastomer resin composition characterized by containing an alicyclic polycarbodiimide compound and/or an aliphatic polycarbodiimide compound (B) in an amount of 0.1 to 2 parts by mass, an aromatic carbodiimide compound (C) in an amount of 0.1 to 2 parts by mass, and a polyamide resin (D) in an amount of 0.5 to 10 parts by mass, based on 100 parts by mass of a thermoplastic polyester elastomer (A),

the thermoplastic polyester elastomer (A) is formed by combining a hard segment composed of a polyester containing an aromatic dicarboxylic acid and an aliphatic and/or alicyclic diol as constituent components with at least 1 kind of soft segment selected from the group consisting of an aliphatic polyether, an aliphatic polyester and an aliphatic polycarbonate.

2. The polyester elastomer resin composition according to claim 1, wherein the alicyclic polycarbodiimide compound and/or the aliphatic polycarbodiimide compound (B) are mixed in an amount such that the amount of the carbodiimide functional group is 0.3 to 1.5 equivalents, when the amount of the terminal carboxyl group of the thermoplastic polyester elastomer (A) is 1.

3. The polyester elastomer resin composition according to claim 1 or 2, wherein the polyamide resin (D) comprises polyamide 6 and/or a 2-or 3-or more-membered copolymerized polyamide resin.

4. The polyester elastomer resin composition according to claim 1 or 2, further comprising at least 1 antioxidant selected from the group consisting of aromatic amine antioxidants, hindered phenol antioxidants, sulfur antioxidants and phosphorus antioxidants, wherein the antioxidant is contained in an amount of 0.01 to 3 parts by mass per 100 parts by mass of the thermoplastic polyester elastomer (A).

5. The polyester elastomer resin composition according to claim 1 or 2, wherein the reduced viscosity of the polyester elastomer resin composition is 2.0 to 3.5dl/g, the acid value is 0 to 5eq/t,

the reduced viscosity was obtained by dissolving 0.02g of the polyester elastomer resin composition sufficiently dried in 10ml of a mixed solvent of phenol/tetrachloroethane having a mass ratio of 6/4, and measuring the solution at 30 ℃ with an Ubbelohde viscometer,

the acid value was obtained by dissolving an accurately weighed 0.2g sample in 20ml of chloroform, and titrating with 0.01N ethanol solution of potassium hydroxide using phenolphthalein as an indicator.

6. The polyester elastomer resin composition according to claim 1 or 2, wherein the reduced viscosity of the polyester elastomer resin composition after treatment at 130 ℃ for 300 hours in a state of being coated with a grease containing a urea compound is 2.0dl/g or more.

7. The polyester elastomer resin composition according to claim 1 or 2, wherein the soft segment of the thermoplastic polyester elastomer resin (a) is an aliphatic polyether.