Polyester elastomer resin composition

Abstract

Provided is a polyester elastomer resin composition which can produce a molded article having excellent sound squeaking resistance and abrasion resistance while maintaining mechanical properties, wherein a lubricant does not dissolve in water even when the molded article is washed with water and does not dissolve even when the molded article is washed with a non-polar solvent (heptane). The polyester elastomer resin composition contains 0.1-5 parts by mass of a polyoxytetramethylene polyoxyethylene glycol (B) per 100 parts by mass of a polyester elastomer (A) composed of: a hard segment made of a polyester containing an aromatic dicarboxylic acid and an aliphatic and / or alicyclic diol as constituent components; and at least one soft segment selected from an aliphatic polyether, an aliphatic polyester, and an aliphatic polycarbonate.

Description

Polyester elastomer resin composition

[0001] The present invention relates to a polyester elastomer resin composition. More specifically, the present invention relates to a polyester elastomer resin composition that retains mechanical properties, and in which a lubricant is insoluble in water when a molded article made of the polyester elastomer resin composition is washed with water or with a nonpolar solvent (heptane), and that has excellent noise reduction and abrasion resistance.

[0002] In order to impart abrasion resistance to thermoplastic polyester elastomers, the incorporation of solid lubricants such as fatty acid amide compounds has been investigated (see Patent Documents 1 and 2).Also, the incorporation of a small amount of a single polyether or a copolymer polyether composed of two or more different types of alkylene units as a liquid lubricant has been investigated (see Patent Documents 3 and 4).

[0003] In the method of adding a solid lubricant as described in Patent Documents 1 and 2, the solid lubricant quickly bleeds out onto the surface of the molded article, and although it can impart short-term wear resistance, the solid lubricant present on the surface is scraped off during a long-term sliding test, making it impossible to exhibit sustained wear resistance. Furthermore, if water is present in areas where the lubricant has been scraped off from the surface of the molded article, local variations in the friction state on the surface of the molded article occur, resulting in vibration noise and a phenomenon known as squealing.

[0004] In the method of adding a single polyether as in Patent Documents 3 and 4, although the lubricant remains on the surface of the molded article continuously for a long period of time, the blended polyether component is hydrophilic, so when the surface of the molded article is washed with water, the lubricant is dissolved or washed away in the water, and is easily scraped off from the surface of the molded article, resulting in problems such as squealing when sliding begins.

[0005] To address this issue, a polyester elastomer resin composition has been proposed that uses a solid lubricant such as a fatty acid amide compound in combination with a liquid lubricant of a copolymer polyether composed of ethylene oxide units and propylene oxide units (see Patent Document 5).

[0006] Japanese Patent Application Laid-Open No. 5-279557 Japanese Patent Application Laid-Open No. 2000-186765 Japanese Patent Application Laid-Open No. 2000-159991 Japanese Patent Application Laid-Open No. 2001-106885 Japanese Patent No. 6844687

[0007] The polyester elastomer resin composition of Patent Document 5 has some effect on noise reduction after water washing. However, for molded products that require higher levels of noise reduction, noise reduction after washing with a non-polar solvent (heptane) is also required in addition to noise reduction after water washing. It has been found that conventional technology cannot achieve noise reduction after washing with these two types of cleaning solvents.

[0008] The present invention was made in view of the current state of the prior art, and its object is to provide a polyester elastomer resin composition that can provide long-term, continuous wear resistance while maintaining mechanical properties, in which the lubricant does not dissolve in water when the molded product is washed with water, and in which the lubricant does not dissolve when the molded product is washed with heptane, and which has excellent noise and squeal resistance after washing.

[0009] As a result of extensive research into achieving the above object, the present inventors have discovered that by using polyoxytetramethylene polyoxyethylene glycol as a lubricant, it is possible to achieve noise reduction and long-term stable wear resistance after washing without easily separating from the surface of molded articles even during water washing and heptane washing, and have thus completed the present invention.

[0010] That is, the present invention is as follows: [1] A polyester elastomer resin composition comprising 100 parts by mass of 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 at least one soft segment selected from aliphatic polyethers, aliphatic polyesters, and aliphatic polycarbonates, and 0.1 to 5 parts by mass of a polyoxytetramethylene polyoxyethylene glycol (B). [2] The polyester elastomer resin composition according to [1], wherein the polyoxytetramethylene polyoxyethylene glycol (B) has a number-average molecular weight of 800 to 4,000. [3] The polyester elastomer resin composition according to [1] or [2], wherein the ratio of tetramethylene oxide units to ethylene oxide units in the polyoxytetramethylene polyoxyethylene glycol (B) is 10:90 to 90:10 (molar ratio). [4] The polyester elastomer resin composition according to [1] or [2], wherein the soft segment of the polyester elastomer (A) is an aliphatic polyether. [5] The polyester elastomer resin composition according to [1] or [2], further comprising 0.5 to 10 parts by mass of a polyamide resin (C) per 100 parts by mass of the polyester elastomer (A). [6] The polyester elastomer resin composition according to [1] or [2], further comprising 0.1 to 5 parts by mass of a thickener (D) per 100 parts by mass of the polyester elastomer (A), wherein the thickener (D) is at least one compound selected from epoxy compounds and carbodiimide compounds. [7] The polyester elastomer resin composition according to [1] or [2], wherein the melt flow rate (MFR) measured at 230°C under a load of 2.16 kg in accordance with the flow test method for thermoplastics specified in JIS K7210 is 3 g / 10 min or less.

[0011] In the polyester elastomer resin composition of the present invention, the specific liquid lubricant bleeds out stably onto the surface layer of a molded article made of the polyester elastomer resin composition, and does not easily come off from the surface of the molded article even when washed with water or heptane, thereby achieving noise reduction after washing and stable wear resistance over the long term.

[0012] [Polyester Elastomer (A)] The polyester elastomer (A) used in the present invention is composed of a hard segment made of a polyester having an aromatic dicarboxylic acid and an aliphatic and / or alicyclic diol as constituent components, and at least one soft segment selected from aliphatic polyethers, aliphatic polyesters, and aliphatic polycarbonates.

[0013] The aromatic dicarboxylic acid constituting the polyester of the hard segments is not particularly limited and is generally a typical aromatic dicarboxylic acid. However, it is desirable that the main aromatic dicarboxylic acid be terephthalic acid or naphthalenedicarboxylic acid (2,6-naphthalenedicarboxylic acid is preferred among isomers). The content of these aromatic dicarboxylic acids is preferably 70 mol% or more, more preferably 80 mol% or more, and even more preferably 90 mol% or more, of the total dicarboxylic acids constituting the polyester of the hard segments. Examples of dicarboxylic acid components other than terephthalic acid and naphthalenedicarboxylic acid include aromatic dicarboxylic acids such as diphenyldicarboxylic acid, isophthalic acid, and 5-sodiumsulfoisophthalic 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. These 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, more preferably 20 mol % or less, and even more preferably 10 mol % or less, of the total acid components, and may be 0 mol %. When these dicarboxylic acids are used as raw materials for the polyester elastomer, they may be in the form of esters of the dicarboxylic acids. For example, terephthalic acid and dimethyl terephthalate can also be used as raw materials.

[0014] The aliphatic or alicyclic diol constituting the polyester of the hard segment is not particularly limited and is generally a widely used aliphatic or alicyclic diol, but 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, and 1,4-butanediol is more preferred.

[0015] As the component constituting the polyester of the hard segment, those comprising butylene terephthalate units (units consisting of terephthalic acid and 1,4-butanediol) or butylene naphthalate units (units consisting of 2,6-naphthalenedicarboxylic acid and 1,4-butanediol) are preferred from the viewpoints of physical properties, moldability, and cost performance.

[0016] The soft segment is at least one selected from aliphatic polyethers, aliphatic polyesters, and aliphatic polycarbonates. Examples of aliphatic polyethers include poly(ethylene oxide) glycol, poly(propylene oxide) glycol, poly(tetramethylene oxide) glycol, poly(hexamethylene oxide) glycol, poly(trimethylene oxide) glycol, copolymers of ethylene oxide and propylene oxide, ethylene oxide adducts of poly(propylene oxide) glycol, and copolymers of ethylene oxide and tetrahydrofuran.

[0017] Examples of aliphatic polyesters include poly(ε-caprolactone), polyenantholactone, polycaprylolactone, polybutylene adipate, etc. Among these aliphatic polyethers and / or aliphatic polyesters, poly(tetramethylene oxide) glycol, an ethylene oxide adduct of poly(propylene oxide) glycol, poly(ε-caprolactone), polybutylene adipate, etc. are preferred from the viewpoint of the elastic properties of the resulting polyester elastomer (A), and among these, poly(tetramethylene oxide) glycol is particularly preferred.

[0018] Furthermore, the aliphatic polycarbonate is preferably composed primarily of aliphatic diol residues having 2 to 12 carbon atoms. Examples of these aliphatic diols include ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 2,2-dimethyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, 1,9-nonanediol, and 2-methyl-1,8-octanediol. In particular, aliphatic diols having 5 to 12 carbon atoms are preferred in terms of the flexibility and low-temperature properties of the resulting polyester elastomer. These components may be used alone or in combination of two or more types as necessary, based on the examples described below.

[0019] The aliphatic polycarbonate diol preferably has a low melting point (for example, 70°C or less) and a low glass transition temperature. In general, an aliphatic polycarbonate diol made of 1,6-hexanediol used to form the soft segment of a polyester elastomer has a low glass transition temperature of around -60°C and a melting point of around 50°C, and therefore has good low-temperature properties. In addition, an aliphatic polycarbonate diol obtained by copolymerizing, for example, an appropriate amount of 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 therefore corresponds to an aliphatic polycarbonate diol with good low-temperature properties. Furthermore, for example, an aliphatic polycarbonate diol made of 1,9-nonanediol and 2-methyl-1,8-octanediol has a melting point of about 30°C and a glass transition temperature of about -70°C, which are sufficiently low, and therefore corresponds to an aliphatic polycarbonate diol with good low-temperature properties.

[0020] From the viewpoint of solving the problems of the present invention, the soft segment of the polyester elastomer (A) is preferably an aliphatic polyether.

[0021] The polyester elastomer (A) is preferably a copolymer primarily composed of terephthalic acid, 1,4-butanediol, and poly(tetramethylene oxide) glycol. Among the dicarboxylic acid components constituting the polyester elastomer (A), terephthalic acid preferably accounts for 40 mol% or more, more preferably 70 mol% or more, even more preferably 80 mol% or more, and particularly preferably 90 mol% or more. Among the glycol components constituting the polyester elastomer (A), the sum of 1,4-butanediol and poly(tetramethylene oxide) glycol is preferably 40 mol% or more, more preferably 70 mol% or more, even more preferably 80 mol% or more, and particularly preferably 90 mol% or more.

[0022] The number average molecular weight of the poly(tetramethylene oxide) glycol is preferably 500 to 4000. If the number average molecular weight is less than 500, it may be difficult to exhibit elastomeric properties. On the other hand, if the number average molecular weight exceeds 4000, the compatibility of the hard segment with the polyester portion may decrease, making it difficult to copolymerize in a block form. The number average molecular weight of the poly(tetramethylene oxide) glycol is more preferably 800 to 3000, and even more preferably 1000 to 2500.

[0023] The copolymerization amount of the poly(tetramethylene oxide) glycol is preferably 5 to 50 mol % based on the total glycol components constituting the polyester elastomer (A), more preferably 5 to 30 mol %, even more preferably 5 to 20 mol %, particularly preferably 7 to 18 mol %, and most preferably 8 to 15 mol %.

[0024] In the polyester elastomer (A), the mass ratio of the hard segment to the soft segment (hard segment:soft segment) is generally preferably in the range of 30:70 to 95:5, more preferably 40:60 to 90:10, even more preferably 45:55 to 87:13, and particularly preferably 50:50 to 85:15.

[0025] The reduced viscosity of the polyester elastomer (A), as measured by the method described below, is preferably 0.5 dl / g or more and 3.5 dl / g or less. If it is less than 0.5 dl / g, the durability as a resin may be reduced, and if it exceeds 3.5 dl / g, the processability in injection molding and the like may be insufficient. The reduced viscosity of the polyester elastomer (A) is more preferably 1.0 dl / g or more and 3.0 dl / g or less, and even more preferably 1.5 dl / g or more and 2.8 dl / g or less. The acid value of the polyester elastomer (A) is preferably 200 eq / t or less, more preferably 50 eq / t or less.

[0026] The melting point of the polyester elastomer (A) is preferably 150 to 230° C., more preferably 175 to 210° C. If the melting point of the polyester elastomer (A) is less than 150° C., the heat resistance may be reduced due to the large amount of soft segments, and if it is more than 230° C., the flexibility may be reduced due to the large amount of hard segments.

[0027] The polyester elastomer (A) can be produced by known methods (e.g., JP-A-10-182954, WO 2007 / 072748, etc.), such as a method of transesterifying a lower alcohol diester of a dicarboxylic acid, an excess amount of a low-molecular-weight glycol, and a soft segment component in the presence of a catalyst, followed by polycondensation of the resulting reaction product, a method of esterifying a dicarboxylic acid, an excess amount of a glycol, and a soft segment component in the presence of a catalyst, followed by polycondensation of the resulting reaction product, a method of pre-preparing a hard segment, adding a soft segment component to the hard segment, and randomizing the hard segment by transesterification, a method of linking the hard segment and the soft segment with a chain linking agent, or, when poly(ε-caprolactone) is used for the soft segment, subjecting the hard segment to an addition reaction of ε-caprolactone monomer.

[0028] [Polyoxytetramethylene polyoxyethylene glycol (B)] The polyoxytetramethylene polyoxyethylene glycol (B) used in the present invention is used as a lubricant to improve friction and wear properties. Polyoxytetramethylene polyoxyethylene glycol (B) is a polyoxyalkylene glycol compound, a compound in which alkylene oxide units consist of tetramethylene oxide units and ethylene oxide units. The number-average molecular weight of polyoxytetramethylene polyoxyethylene glycol (B) is preferably 800 to 4000, more preferably 1200 to 4000, and even more preferably 1500 to 3500. If the number-average molecular weight is below the lower limit, the lubricant may precipitate (bleed out) too quickly on the surface of a molded article, and the lubricant may be easily scraped off from the surface of the molded article during an abrasion test. In other words, if the number average molecular weight is equal to or greater than the lower limit, the rate at which the lubricant precipitates on the surface of the molded article is appropriately fast, and the lubricant is not easily scraped off from the surface of the molded article during an abrasion test. This effect can be more pronounced when the number average molecular weight is 1,200 or more. If the number average molecular weight exceeds the upper limit, the rate at which the lubricant precipitates on the surface of the molded article is too slow, and there is a risk that the abrasion resistance and noise reduction properties will not be fully exhibited. The number average molecular weight can be measured by the method described in the Examples section below.

[0029] The polyoxytetramethylene polyoxyethylene glycol (B) that can be preferably used is one represented by the following formula (1):

[0030]

[0031] In formula (1), a, b, and n represent integers of 1 or greater. (However, the values ​​of a and b may be different for each repeat in the square brackets.) In this case, the ratio of tetramethylene oxide units to ethylene oxide units (tetramethylene oxide units:ethylene oxide units) is preferably 10:90 to 90:10 (molar ratio), more preferably 30:70 to 60:40 (molar ratio). Furthermore, it is preferable that the tetramethylene oxide units and ethylene oxide units are copolymerized randomly.

[0032] The amount of polyoxytetramethylene polyoxyethylene glycol (B) may vary depending on its affinity with the polyester elastomer (A) used or the required properties of the final composition. Two or more types of polyoxytetramethylene polyoxyethylene glycol (B) may be used in combination, or may be used in combination with other lubricant components. The amount of each component described below refers to the content in the polyester elastomer resin composition.

[0033] The amount of polyoxytetramethylene polyoxyethylene glycol (B) is 0.1 to 5 parts by mass, preferably 0.3 to 5 parts by mass, and more preferably 0.8 to 4 parts by mass, per 100 parts by mass of the polyester elastomer (A). If the amount is less than 0.1 part by mass, the effects (reduction of friction noise and wear) obtained by adding polyoxytetramethylene polyoxyethylene glycol (B) may not be significantly exhibited. If the amount exceeds 5 parts by mass, the melt viscosity of the polyester elastomer may be significantly reduced, making molding impossible, or the surface hardness and mechanical properties of the molded product may be reduced. Furthermore, the polyoxytetramethylene polyoxyethylene glycol (B) may significantly ooze out of the surface of the molded product, resulting in adverse effects such as poor appearance and scattering to surrounding parts.

[0034] When viewed at a molecular level, polyoxytetramethylene polyoxyethylene glycol (B) is an aggregate of many types of molecules with different properties, and therefore tends to gradually bleed out from the polyester elastomer, allowing it to exhibit wear resistance and sound-deadening effects over a long period of time.

[0035] The reason why polyoxytetramethylene polyoxyethylene glycol (B) is not scraped off from the surface of the molded article during water washing is thought to be as follows: The tetramethylene oxide unit of polyoxytetramethylene polyoxyethylene glycol (B) has excellent compatibility with the polyester elastomer (A). On the other hand, the ethylene oxide unit of polyoxytetramethylene polyoxyethylene glycol (B) has poor compatibility with the polyester elastomer (A). Therefore, it is thought that the appropriate interaction between the polyester elastomer (A) and polyoxytetramethylene polyoxyethylene glycol (B) causes the lubricant to bleed out stably to the surface of the molded article, and that this appropriate interaction allows the lubricant to remain even during water washing.

[0036] The reason why polyoxytetramethylene polyoxyethylene glycol (B) is not scraped off from the surface of the molded article during heptane washing is thought to be as follows: The ethylene oxide units of polyoxytetramethylene polyoxyethylene glycol (B) have a high ratio of ether groups in the alkylene oxide units and are more polar than tetramethylene oxide units. This is thought to be why they have low solubility in heptane, allowing the lubricant to remain even during heptane washing.

[0037] [Polyamide Resin (C)] The polyamide resin (C), optionally used in the present invention, serves to improve the heat aging resistance of the polyester elastomer. Polyamide resin (C) is a polymeric compound having an amide bond in the molecular chain. Examples of suitable polyamide resins include polyamides 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 obtained from lactams; and polymers obtained from ω-aminocarboxylic acids. Examples of suitable polyamide resins include polymers of salts obtained by reacting adipic acid, sebacic acid, linoleic acid, or dodecanedioic acid with ethylenediamine, hexamethylenediamine, or metaxylylenediamine. These copolymers or combinations of two or more thereof may also be used. Specifically, polyamide 4, polyamide 6, polyamide 7, polyamide 8, polyamide 9, polyamide 11, polyamide 12 obtained from lactam or ω-aminocarboxylic acid, polyamide 66, polyamide 69, polyamide 610, polyamide 611, polyamide 612, polyamide 6T, polyamide 6I, polyamide MXD6 obtained from diamine and dicarboxylic acid, and copolymers thereof such as polyamide 6 / 66, polyamide 6 / 610, polyamide 6 / 6T, polyamide 6I / 6T, polyamide 6 / 66 / 12, etc. Among these polyamide resins, more excellent effects can be achieved when polyamide 6 and / or a di- or ternary or higher copolymer polyamide resin is used. As the polyamide resin (C), a di- or ternary or higher copolymer polyamide resin is more preferred.

[0038] The polyamide resin (C) preferably has an amine value of 50 to 2000 eq / t. Having an amine value within this range enhances the heat aging resistance of the polyester elastomer. The amine value is more preferably 70 to 1000 eq / t, even more preferably 100 to 700 eq / t, and particularly preferably 100 to 550 eq / t.

[0039] The blending amount of polyamide resin (C) is preferably 0.5 to 10 parts by mass per 100 parts by mass of thermoplastic polyester elastomer (A). If the blending amount of polyamide resin (C) is greater than the above range, the inherent properties of polyester elastomer (A) may be impaired, while if the blending amount is less than the above range, the effect of improving heat aging resistance is small. The blending amount of polyamide resin (C) is more preferably 1 to 7 parts by mass, and even more preferably 1 to 3 parts by mass per 100 parts by mass of polyester elastomer (A).

[0040] [Thickener (D)] The thickener (D) optionally used in the present invention is a reactive compound (hereinafter sometimes simply referred to as a reactive compound) having a functional group capable of reacting with the hydroxyl or carboxyl groups of the polyester elastomer (A). The functional group is preferably at least one selected from the group consisting of an epoxy group (glycidyl group), an acid anhydride group, a carbodiimide group, and an isocyanate group, and preferably contains two or more functional groups per molecule. The functional group is more preferably an epoxy group (glycidyl group) or a carbodiimide group. The thickener (D) is particularly preferably an epoxy compound and / or a carbodiimide compound.

[0041] The epoxy compound is a multifunctional epoxy compound having two or more epoxy groups. Specific examples include 1,6-dihydroxynaphthalene diglycidyl ether and 1,3-bis(oxiranylmethoxy)benzene, each having two epoxy groups; 1,3,5-tris(2,3-epoxypropyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione and diglycerol triglycidyl ether, each having three epoxy groups; and 1-chloro-2,3-epoxypropane-formaldehyde-2,7-naphthalenediol polycondensates and pentaerythritol polyglycidyl ether, each having four epoxy groups. Among these, multifunctional epoxy compounds having heat resistance in the skeleton are preferred. In particular, bifunctional or tetrafunctional epoxy compounds having a naphthalene structure as the skeleton, or trifunctional epoxy compounds having a triazine structure as the skeleton are preferred. Considering the degree of increase in the solution viscosity of the polyester elastomer (A), the effect of efficiently reducing the acid value of the polyester elastomer (A), and the degree of gelation due to aggregation and solidification of the epoxy itself, a difunctional or trifunctional epoxy compound is preferred.

[0042] The carbodiimide compound may be a polycarbodiimide compound having two or more carbodiimide groups (—N═C═N— structure) in one molecule, and examples thereof include an aliphatic polycarbodiimide compound, an alicyclic polycarbodiimide compound, an aromatic polycarbodiimide compound, and copolymers thereof. An aliphatic polycarbodiimide compound or an alicyclic polycarbodiimide compound is preferred.

[0043] The polycarbodiimide compound can be obtained, for example, by the decarbonation reaction of a diisocyanate compound. Examples of diisocyanate compounds that can be used here include 4,4'-diphenylmethane diisocyanate, 4,4'-diphenyldimethylmethane diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,5-naphthylene diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, cyclohexane-1,4-diisocyanate, xylylene diisocyanate, isophorone diisocyanate, methylcyclohexane diisocyanate, tetramethylxylylene diisocyanate, and 1,3,5-triisopropylphenylene-2,4-diisocyanate. These compounds may be used alone or in the form of a copolymer of two or more compounds. In addition, a branched structure may be introduced, or a functional group other than a carbodiimide group or an isocyanate group may be introduced by copolymerization. Furthermore, although the terminal isocyanate may be used as it is, the degree of polymerization may be controlled by reacting the terminal isocyanate, or a portion of the terminal isocyanate may be blocked.

[0044] As the polycarbodiimide compound, alicyclic polycarbodiimides derived from dicyclohexylmethane diisocyanate, cyclohexane-1,4-diisocyanate, isophorone diisocyanate, etc. are particularly preferred, and polycarbodiimides derived from dicyclohexylmethane diisocyanate or isophorone diisocyanate are particularly preferred.

[0045] From the viewpoints of stability and ease of handling, it is preferable for the polycarbodiimide compound to contain 2 to 50 carbodiimide groups per molecule. More preferably, it is preferable for the polycarbodiimide compound to contain 5 to 30 carbodiimide groups per molecule. The number of carbodiimide groups in a polycarbodiimide molecule (i.e., the number of carbodiimide groups) corresponds to the degree of polymerization for polycarbodiimides obtained from diisocyanate compounds. For example, a polycarbodiimide obtained by linking 21 diisocyanate compounds in a chain has a degree of polymerization of 20, and the number of carbodiimide groups in the molecular chain is 20. Polycarbodiimide compounds are typically mixtures of molecules of various lengths, and the number of carbodiimide groups is expressed as an average value. A polycarbodiimide compound having the number of carbodiimide groups within the above range and being solid at or near room temperature can be powdered, resulting in excellent workability and compatibility when mixed with the polyester elastomer (A), and is also preferable in terms of uniform reactivity and bleed-out resistance. The number of carbodiimide groups can be measured, for example, by a conventional method (a method in which a compound is dissolved in an amine and then back-titrated with hydrochloric acid).

[0046] From the viewpoint of stability and ease of handling, it is preferable that the polycarbodiimide compound has an isocyanate group at its terminal, and that the isocyanate group content is 0.5 to 4 mass%. More preferably, the isocyanate group content is 1 to 3 mass%. In particular, polycarbodiimides derived from dicyclohexylmethane diisocyanate or isophorone diisocyanate and having an isocyanate group content within the above range are preferred. The isocyanate group content can be measured using a standard method (a method in which a compound is dissolved in an amine and then back-titrated with hydrochloric acid).

[0047] The blending amount of thickener (D) is preferably 0.1 to 5 parts by mass per 100 parts by mass of polyester elastomer (A). Less than 0.1 part by mass results in an insufficient molecular chain elongation effect, whereas more than 5 parts by mass results in an excessive thickening effect, which tends to adversely affect moldability and the mechanical properties of the molded article. When thickener (D) is an epoxy compound, more than 5 parts by mass may result in unevenness on the surface of the molded article due to the aggregation and hardening of the epoxy compound. When thickener (D) is a carbodiimide compound, more than 5 parts by mass may result in hydrolysis of polyester elastomer (A) due to the basicity of the polycarbodiimide compound, which tends to affect the mechanical properties.

[0048] The thickener (D) may be either an epoxy compound or a carbodiimide compound. The thickener (D) may also be a combination of an epoxy compound and a carbodiimide compound. In this case, the upper limits of the respective contents are proportionally determined according to the content ratio of the epoxy compound and the carbodiimide compound. For example, when the epoxy compound and the carbodiimide compound are used in a mass ratio of 50:50, the upper limit of the epoxy compound may be 2.5 parts by mass, and the upper limit of the carbodiimide compound may be 2.5 parts by mass.

[0049] [Other Additives] In addition to the above components (A) to (D), the resin composition of the present invention can contain general-purpose antioxidants such as aromatic amine-based, hindered phenol-based, phosphorus-based, and sulfur-based antioxidants. Two or more of these may be used in combination. Specific examples of aromatic amine-based antioxidants include phenylnaphthylamine, 4,4'-dimethoxydiphenylamine, 4,4'-bis(α,α-dimethylbenzyl)diphenylamine, and 4-isopropoxydiphenylamine.

[0050] As the hindered phenol-based antioxidant, any general-purpose compound can be used, but those having a molecular weight of 500 or more, such as N,N'-hexamethylene-bis(3,5-di-t-butyl-4-hydroxyhydrocinnamic acid amide) and tetrakis[methylene-3(3,5-di-t-butyl-4-hydroxyphenyl)propionate]methane, are preferred because they are less likely to volatilize in a high-temperature atmosphere.

[0051] Examples of phosphorus-based antioxidants include phosphorus-containing compounds such as phosphoric acid, phosphorous acid, hypophosphorous acid derivatives, phenylphosphonic acid, polyphosphonates, and diphosphite compounds. Specific examples include triphenyl phosphite, diphenyldecyl phosphite, phenyl diisodecyl phosphite, tri(nonylphenyl)phosphite, bis(2,4-di-t-butylphenyl)pentaerythritol diphosphite, and bis(2,6-di-t-butyl-4-methylphenyl)pentaerythritol diphosphite.

[0052] Examples of sulfur-based antioxidants include sulfur-containing compounds such as thioethers, dithioacid salts, mercaptobenzimidazoles, thiocarbanilides, and thiodipropionate esters. Specific examples include dilauryl thiodipropionate, distearyl thiodipropionate, didodecyl thiodipropionate, ditetradecyl thiodipropionate, dioctadecyl thiodipropionate, pentaerythritol tetrakis(3-dodecylthiopropionate), thiobis(N-phenyl-β-naphthylamine), 2-mercaptobenzothiazole, 2-mercaptobenzimidazole, tetramethylthiuram monosulfide, tetramethylthiuram disulfide, nickel dibutyldithiocarbamate, nickel isopropyl xanthate, and trilauryl trithiophosphite. Thioether-based antioxidants having a thioether structure are particularly suitable because they accept oxygen from oxidized substances and reduce them.

[0053] The amount of each of the antioxidants is preferably 0.01 to 3 parts by mass, more preferably 0.05 to 2 parts by mass, and even more preferably 0.1 to 1 part by mass, per 100 parts by mass of the polyester elastomer (A).

[0054] The composition and composition ratio of the polyester elastomer resin composition used in the present invention can be determined by dissolving a sample in a solvent such as deuterated chloroform and measuring the composition. １ It can also be calculated from the proton integral ratio of H-NMR.

[0055] Furthermore, if 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, or salicylic acid-based light stabilizers can be used. The amount added is preferably 0.1% or more and 5% or less by mass of the resin composition.

[0056] The polyester elastomer resin composition of the present invention can contain various other additives. Other additives include resins other than those mentioned above, inorganic fillers, stabilizers, and antioxidants, as long as they do not impair the characteristics of the present invention. Other additives that can be added include color pigments, inorganic and organic fillers, coupling agents, tackiness improvers, stabilizers such as quenchers and metal deactivators, and flame retardants. The total amount of these various additives is preferably 20 parts by mass or less, and more preferably 10 parts by mass or less, per 100 parts by mass of the polyester elastomer (A).

[0057] The MFR of the polyester elastomer resin composition of the present invention is not particularly limited, but is preferably 0.1 to 30 g / 10 min for the purpose of obtaining a general injection-molded product. However, from the viewpoint of further improving heat aging resistance and blow moldability, it is preferably 3 g / 10 min or less, and more preferably 0.1 to 3 g / 10 min. The MFR can be measured by the method described in the Examples section below.

[0058] The resin composition of the present invention can be produced by melt-kneading the components using a conventional thermoplastic resin mixer, such as a single-screw or twin-screw melt-kneader or a kneader-type heater, followed by pelletizing the components in a granulation step.

[0059] The following examples are provided to further illustrate 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.

[0060] Melting point: Using a differential scanning calorimeter "DSC220" manufactured by Seiko Instruments Inc., 5 mg of a measurement sample was placed in an aluminum pan, the lid was pressed down to seal the pan, and the pan was held at 250°C for 5 minutes to completely melt the sample, followed by rapid cooling with liquid nitrogen. Thereafter, the sample was measured from -150°C to 250°C at a heating rate of 20°C / min. The endothermic peak temperature of the obtained thermogram curve was taken as the melting point.

[0061] Reduced viscosity: 0.10 g of a thoroughly dried resin was dissolved in 25 ml of a mixed solvent of phenol / tetrachloroethane (mass ratio 6 / 4), and the reduced viscosity was measured at 30° C. using an Ubbelohse viscometer.

[0062] Acid value: 0.2 g of a sample was accurately weighed, dissolved in 20 ml of chloroform, and titrated with 0.01 N potassium hydroxide (ethanol solution). Phenolphthalein was used as an indicator.

[0063] Amine value (eq / ton): 3 g of a sample was weighed and dissolved in 80 ml of m-cresol, and the solution was titrated by potentiometric titration using "AT-500N" manufactured by Kyoto Electronics Manufacturing Co., Ltd. and a 0.05 mol / L perchloric acid methanol solution as a titrant to determine the amine value.

[0064] Relative Viscosity: The relative viscosity of polyamide resins is generally measured using three types of solvents, namely, meta-cresol, 96% sulfuric acid, and 90% formic acid, depending on the type of solvent used for dissolution. The relative viscosity of polyamide resin (C) in the present invention was measured in a 98% sulfuric acid solution (polyamide resin concentration 1 g / dl, temperature 25°C).

[0065] Number average molecular weight of polyoxytetramethylene polyoxyethylene glycol (B): A sample was dissolved in deuterated chloroform (CDCl ３ ) / trifluoroacetic acid (TFA) = 85 / 15 (volume ratio), １ The number average molecular weight was calculated from the spectral ratio of tetramethylene oxide to ethylene oxide obtained by H-NMR and the amount of terminals. This method was also used for (B'-1) used in the comparative example.

[0066] The following materials were used as raw materials. [Polyester elastomer (A)] (A-1) Polyester elastomer A1 Polyester elastomer A1 having a molar ratio of terephthalic acid / 1,4-butanediol / poly(tetramethylene oxide) glycol (PTMG; number average molecular weight 1,500) of 100 / 88 / 12 was produced in accordance with the method described in Reference Example 1 of JP-A No. 9-59491. This polyester elastomer A1 had a melting point of 197°C, a reduced viscosity of 1.86 dl / g, and an acid value of 38 eq / t. (A-2) Polyester elastomer A2 Polyester elastomer A2 having a molar ratio of terephthalic acid / 1,4-butanediol / poly(tetramethylene oxide) glycol (PTMG; number average molecular weight 2000) of 100 / 90 / 10 was produced in accordance with the method described in Reference Example 1 of JP-A No. 9-59491. The melting point of this polyester elastomer A2 was 205°C, the reduced viscosity was 2.15 dl / g, and the acid value was 35 eq / t.

[0067] [Polyoxytetramethylene polyoxyethylene glycols (B)] (B-1) Polyserine DC-1800E (manufactured by NOF Corporation, number average molecular weight 1800, tetramethylene oxide unit / ethylene oxide unit=46 / 54 [molar ratio]) (B-2) Polyserine DC-3000E (manufactured by NOF Corporation, number average molecular weight 3000, tetramethylene oxide unit / ethylene oxide unit=53 / 47 [molar ratio]) (B-3) Polyserine DC-1100 (manufactured by NOF Corporation, number average molecular weight 1000, tetramethylene oxide unit / ethylene oxide unit=35 / 65 [molar ratio])

[0068] [Other Polyether Glycol Compounds] (B'-1) Polyserine DCB-2000 (polyoxytetramethylene polyoxypropylene glycol) (manufactured by NOF Corporation, number average molecular weight 2000, tetramethylene oxide unit / propylene oxide unit = 61:39 [molar ratio]) (B'-2) PEG-1540 (polyethylene glycol) (manufactured by Sanyo Chemical Industries, Ltd., number average molecular weight 1450) (B'-3) PTMG3000 (poly(tetramethylene oxide) glycol) (manufactured by Mitsubishi Chemical Corporation, number average molecular weight 3000)

[0069] [Polyamide Resin (C)] (C-1) Polyamide Resin C1 (Polyamide 6 / 66 / 12) (Relative Viscosity 1.3, Amine Value 490 eq / t)

[0070] [Thickener (D)] (D-1) TEPIC-S (triazine skeleton-containing trifunctional epoxy compound) (manufactured by Nissan Chemical Industries, Ltd.) (D-2) Carbodilite HMV-15CA (alicyclic polycarbodiimide compound) (manufactured by Nisshinbo Industries, Inc.)

[0071] [Other additives] Aromatic amine antioxidant: Nonflex DCD (manufactured by Ouchi Shinko Chemical Co., Ltd.) (4,4'-bis(α,α-dimethylbenzyl)diphenylamine) Hindered phenol antioxidant: Irganox 1010 (manufactured by BASF) Hindered phenol antioxidant: Irganox 1098 (manufactured by BASF) Sulfur-based antioxidant: Lasmit LG (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) (dilauryl thiodipropionate)

[0072] Examples 1 to 8 and Comparative Examples 1 to 6: The above components were dry-blended in the ratios shown in Table 1, kneaded, and pelletized in a twin-screw extruder. The pellets of this polyester elastomer resin composition were used for the following evaluations. Furthermore, the test specimens used for surface hardness, bleed amount, lubricant residual rate after water washing, lubricant residual rate after heptane washing, abrasion test, and squeal test were injection-molded articles (100mm square test specimens: width 100mm, length 100mm, thickness 2.0mm) prepared in an injection molding machine at a cylinder temperature of 240°C and a mold temperature of 50°C. The results are shown in Table 1.

[0073] Surface hardness: The surface hardness was measured in an environment of 23°C according to the test method described in ISO 48-4. Three 100mm square test pieces were stacked on top of each other, and a needle tip was dropped onto them. The value 15 seconds after the test piece and the needle tip came into contact was read to measure the surface hardness.

[0074] Melt viscosity (MFR): The melt flow rate (MFR: g / 10 min) was measured at a temperature of 230° C. and a load of 2,160 g in accordance with the test method (Method A) described in JIS K7210. A composition with a moisture content of 0.1% by mass or less was used for the measurement.

[0075] Bleeding amount (23°C): A 100mm square test piece was left to stand for 2 weeks in an environment of 23°C / 50% RH. Thereafter, the mass of the molded article was measured, the surface of the molded article was carefully wiped with a Kimwipe, and the mass of the molded article was measured again. The amount of bleeding of the lubricant was measured from the difference in mass before and after wiping.

[0076] Abrasion test (presence or absence of abrasion powder): A 100mm square test piece was left to stand in an environment of 23°C / 50% RH for 2 weeks. Thereafter, a thrust abrasion test according to JIS K7213 was carried out to check for the presence or absence of abrasion powder on the surface of the molded product, and the results were evaluated according to the following criteria. The cylindrical test piece used in the thrust abrasion test was made of SUS-65C, and the sliding test was carried out under a load of 1.0 MPa, a sliding speed of 100 rpm, and a test time of 60 minutes. No abrasion powder was observed on the surface of the molded product: A Slight abrasion powder was observed on the surface of the molded product: B Abrasion powder was observed on the surface of the molded product: C

[0077] Lubricant Residual Rate after Water Washing: A 100mm square test piece was left standing for two weeks in a 23°C / 50% RH environment. Thereafter, water was sprayed onto the molded product, and wiping was performed using a thrust abrasion tester. A rag was sandwiched between the cylindrical test piece (SUS-65C) and the molded product, and wiping was performed under a load of 0.5 MPa, a sliding speed of 50 rpm, and a wiping time of 5 minutes. The surface of the molded product before and after wiping was compared by infrared absorption spectroscopy (IR), and the presence or absence of a peak derived from the lubricant after wiping was confirmed as the lubricant residual rate. Specifically, the lubricant residual rate was determined as 1360 to 1370 cm ―１ In the region of [(absorbance before washing) - (absorbance after washing)] / [(absorbance before washing) - (absorbance derived from polyester elastomer)] x 100.

[0078] Lubricant Remaining Rate after Heptane Washing: A 100mm square test piece was left standing for two weeks in a 23°C / 50% RH environment. Heptane was then sprayed onto the molded product, and wiping was performed using a thrust abrasion tester. A cloth was placed between the cylindrical test piece (SUS-65C) and the molded product, and wiping was performed under a load of 0.5 MPa, a sliding speed of 50 rpm, and a wiping time of 5 minutes. The surface of the molded product before and after wiping was compared using infrared absorption spectroscopy (IR), and the presence or absence of a peak derived from the lubricant after wiping was confirmed as the lubricant remaining rate. Specifically, the lubricant remaining rate was determined as 1360 to 1370 cm ―１ In the region of [(absorbance before washing) - (absorbance after washing)] / [(absorbance before washing) - (absorbance derived from polyester elastomer)] x 100.

[0079] Squeak Test (presence or absence of squealing): 100mm square test pieces were left stationary in a 23°C / 50% RH environment for two weeks. The molded product was then sprayed with water or heptane and wiped using a thrust abrasion tester. A rag was sandwiched between the cylindrical test piece (SUS-65C) and the molded product, and the test was performed under a load of 0.5 MPa, a sliding speed of 50 rpm, and a wiping time of 5 minutes. Furthermore, water was dropped onto the surface of the molded product after wiping, and a thrust abrasion test was performed to confirm the presence or absence of squealing. The cylindrical test pieces used for the thrust abrasion test were injection-molded from the same resin as the 100mm square test pieces at a cylinder temperature of 240°C. The sliding test was performed under a load of 0.5 MPa, a sliding speed of 50 rpm, and a test time of 5 minutes. The noise generated during the test was measured using a Rion NL-20 sound level meter.

[0080] Tensile test (elongation at break) after heat aging: An injection-molded product (width 100 mm, length 100 mm, thickness 2.0 mm) produced at a cylinder temperature of 240°C and a mold temperature of 50°C was punched out in the direction perpendicular to the resin flow direction into a JIS No. 3 dumbbell shape to prepare a test piece. The test piece was annealed in a hot air dryer at 150°C for 500 hours, and then the elongation at break was measured in accordance with JIS K6251:2010.

[0081] Flexural fatigue test: Using a Dematcia flexural crack tester BE-102 (manufactured by Tester Sangyo Co., Ltd.), the following specified test pieces were subjected to repeated bending at a rate of 300 times / min with the chuck distance set to 75 mm and 19 mm in an atmosphere of 130 ° C., and the flexural fatigue resistance was evaluated based on the number of times until fracture. As the test piece, an injection-molded product (width 20 mm, length 100 mm, thickness 3.6 mm, with a groove of R2.4 across the entire 20 mm width in the center of the longitudinal direction) prepared at a cylinder temperature of 240 ° C. and a mold temperature of 50 ° C. was used.

[0082]

[0083] In Examples 1 to 8, a specific liquid lubricant, polyoxytetramethylene polyoxyethylene glycol (B), was blended with a polyester elastomer to provide resin compositions that maintained mechanical properties while also exhibiting bleed-out properties, long-term stable abrasion resistance, high lubricant retention after water washing and heptane washing, and noise and squeal resistance. In particular, Examples 1 to 3 and 5 to 8 had a higher molecular weight of polyoxytetramethylene polyoxyethylene glycol (B) than Example 4, resulting in superior results in abrasion tests. In Examples 6 to 8, a polyamide resin (C) was further blended to provide resin compositions that maintained noise and squeal resistance while improving heat aging resistance. In Examples 7 and 8, a thickener (D) was further blended to provide resin compositions with a low MFR and improved flex fatigue resistance.

[0084] In Comparative Example 1, since no lubricant component was added, the lubricant did not bleed out onto the surface of the molded product, resulting in poor abrasion resistance and squealing after both water washing and heptane washing. Because no lubricant component was included, the lubricant remaining after water washing and heptane washing were not evaluated.

[0085] In Comparative Example 2, polyoxytetramethylene polyoxypropylene glycol (DCB-1000), which has a different copolymerization component, was added as the lubricant component. Because it does not contain ethylene oxide units, it has high compatibility with polyester elastomers and insufficient bleeding. Furthermore, because it is easily soluble in heptane, the lubricant remains low after heptane washing, causing squealing.

[0086] Comparative Example 3 is a case where polyethylene glycol (PEG-1540) was added as a lubricant component, but it had low compatibility with polyester elastomer and bleeds out a lot. This lubricant is a highly polar polyether, so the lubricant remains low after water washing, causing squealing. Furthermore, although the lubricant remains high after heptane washing, water is dropped into the thrust wear test after heptane washing, so squealing still occurs.

[0087] In Comparative Example 4, poly(tetramethylene oxide) glycol (PTMG3000) was added as a lubricant component, but its compatibility with the polyester elastomer was too high, resulting in a small amount of bleeding. Furthermore, the lubricant remained poorly after heptane washing, resulting in squealing.

[0088] In Comparative Example 5, polyethylene glycol (PEG-1540) and poly(tetramethylene oxide) glycol (PTMG3000) were added as lubricant components, and the tetramethylene oxide unit and the ethylene oxide unit were not contained in a single molecule, but were added as separate compounds. As in Comparative Examples 3 and 4, the lubricant remained poorly after heptane washing, resulting in squealing.

[0089] Comparative Example 6 is a case in which a large amount of polyoxytetramethylene polyoxyethylene glycol (DC-1800E) was added as a lubricant component, and although noise reduction properties were exhibited, the surface hardness of the molded article itself decreased and the MFR increased significantly, resulting in a significant decrease in mechanical properties.

[0090] The present invention provides a polyester elastomer resin composition that can provide long-term, continuous wear resistance, and in which the lubricant is not removed even when the molded product is washed with water or heptane, resulting in excellent noise and squeal resistance after washing. This makes the composition useful for applications requiring the above-mentioned excellent properties, such as automobile and home appliance parts. It is particularly useful for automobile interior applications and automobile suspension components, which require high sliding properties.

Claims

1. A polyester elastomer resin composition comprising 100 parts by mass of a polyester elastomer (A) which is constituted by a hard segment made of a polyester having an aromatic dicarboxylic acid and an aliphatic and / or alicyclic diol as its constituent components, and at least one soft segment selected from an aliphatic polyether, an aliphatic polyester, and an aliphatic polycarbonate, and which contains 0.1 to 5 parts by mass of polyoxytetramethylene polyoxyethylene glycol (B).

2. The polyester elastomer resin composition according to claim 1, wherein the polyoxytetramethylene polyoxyethylene glycol (B) has a number average molecular weight of 800 to 4,000.

3. A polyester elastomer resin composition according to claim 1 or 2, wherein the ratio of tetramethylene oxide units to ethylene oxide units in the polyoxytetramethylene polyoxyethylene glycol (B) is 10:90 to 90:10 (molar ratio).

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

5. The polyester elastomer resin composition according to claim 1 or 2, further comprising 0.5 to 10 parts by mass of a polyamide resin (C) per 100 parts by mass of the polyester elastomer (A).

6. The polyester elastomer resin composition according to claim 1 or 2, further comprising 0.1 to 5 parts by mass of a thickener (D) per 100 parts by mass of the polyester elastomer (A), said thickener (D) being at least one compound selected from the group consisting of epoxy compounds and carbodiimide compounds.

7. A polyester elastomer resin composition according to claim 1 or 2, which has a melt flow rate (MFR) value of 3 g / 10 min or less at 230°C and a load of 2.16 kg, measured in accordance with the flow test method for thermoplastics specified in JIS K7210.

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