JP5085174B2 - Thermoplastic elastomer composition - Google Patents

Description

  The present invention relates to a thermoplastic elastomer composition.

  In recent years, thermoplastic elastomers, which are rubber-like soft materials that do not require a vulcanization process and have the same molding processability as thermoplastic resins, have become automotive parts, household appliance parts, electric wire coatings, medical parts, footwear, and miscellaneous goods. It is used in such fields. Among thermoplastic elastomers, block copolymers having an aromatic vinyl compound polymer block and a conjugated diene polymer block or styrene thermoplastic elastomers typified by hydrogenated products thereof are excellent in flexibility and moldability. In recent years, improvement in heat resistance has been demanded as fields of use such as home appliance parts, automobile parts, and building material parts expand.

  Regarding the provision of heat resistance to a polymer composition mainly composed of a styrenic thermoplastic elastomer, [1] a block copolymer having a polymer block composed of an aromatic vinyl compound and a polymer block composed of a conjugated diene compound. A hydrogenated product, a non-aromatic rubber softener, a peroxide-decomposable olefin resin, and a compound containing a specific amount of an inorganic filler as required are kneaded in advance, and then an organic peroxide and a crosslinking aid. And a method for producing an elastomeric composition which is partially crosslinked by adding an antioxidant as the case may be, and an elastomeric composition having excellent physical properties such as high-temperature compression set can be obtained (see Patent Document 1); ] A polymer block comprising an aromatic vinyl compound and a polymer block comprising a conjugated diene compound, and having a specific molecular weight distribution. The ratio of the hydrogenated copolymer and the rubber softener is 20/80 to 80/20 (mass ratio), and the specific amount of the olefin polymer is 100 parts by mass with respect to the total amount of the two components. A thermoplastic elastomer composition obtained by dynamically heat-treating a blended mixture in the presence of a crosslinking agent (see Patent Document 2) is known. However, in these compositions, since only the soft segment composed of the conjugated diene compound polymer block of the hydrogenated block copolymer is crosslinked, rubber elasticity (compression set) at 100 ° C. or higher is not good. It is sufficient and has not reached the level achieved with vulcanized rubber.

  [3] In a block copolymer having at least one aromatic vinyl compound polymer block and at least one conjugated diene compound polymer block for the purpose of improving compression set (rubber elasticity) at 100 ° C. or higher. , A thermoplastic compound containing a specific amount of a block copolymer having a specific cross-linked structure or a hydrogenated product thereof, a polyolefin, and, optionally, a rubber softener, which is cross-linked with an aromatic vinyl compound polymer block portion forming at least a hard segment An elastomer composition has been proposed, and it is disclosed that such a thermoplastic elastomer composition is excellent in strain recovery (heat resistance) at high temperatures (see Patent Document 3). However, this thermoplastic elastomer composition has a problem that when it is crosslinked to impart heat resistance, a crosslinked gel is formed, and the smoothness of the surface of the extruded product is poor.

  [4] (a) Hydrogenated block copolymer having a polymer block made of an aromatic vinyl compound and a polymer block made of a conjugated diene compound, and (b) a non-aromatic system Includes specific amounts of rubber softener, (c) peroxide-crosslinked olefin resin, and / or copolymer containing it, (d) peroxide-decomposable olefin resin, and / or copolymer containing it In the method for producing a thermoplastic elastomer resin composition, components (a) and (b), at least a part of component (c), and a part of component (d) are heat-treated in the presence of an organic peroxide for crosslinking. Then, the cross-linked product and the remainder of (d) or the remainder of (c) and (d) are blended, and a polyester-based thermoplastic elastomer and an inorganic filler are added at any stage as necessary. And a method for producing a thermoplastic elastomer resin composition characterized in that an electron donor component is blended before or during heat treatment in the presence of an organic peroxide, and the appearance of the molded body is suppressed by suppressing cross-linking gel Is disclosed (see Patent Document 4). However, in this production method, it is necessary to knead the mixture to which toluene or methanol is added at a temperature equal to or higher than its boiling point, which is problematic in terms of safety.

JP 59-131613 A JP 2000-109640 A International Publication No. 02/090433 Pamphlet JP-A-8-225713

  Therefore, the object of the present invention is to solve such conventional problems, and to provide a thermoplastic elastomer that gives a molded article having excellent strain recovery at high temperatures (heat resistance), extrusion processability, and excellent surface properties. It is to provide a composition.

According to the present invention, the above object is
(1) Polymer block A mainly composed of an aromatic vinyl compound unit and containing 1% by mass or more of a structural unit (a) derived from alkylstyrene having an alkyl group having 1 to 8 carbon atoms bonded to a benzene ring, and a conjugate With respect to 100 parts by mass of at least one addition polymerization block copolymer (I) selected from a block copolymer having a polymer block B mainly composed of diene units and a hydrogenated product thereof, an olefin resin (II ) 10-300 parts by weight, cross-linking agent (III) 0.01-20 parts by weight, cross-linking aid (IV) 0.5-50 parts by weight having two or more methacryloyl groups and hydroxyl groups, and rubber softener (V) 30 to 250 parts by mass parts a thermoplastic elastomer composition obtained by heat treating in a molten condition, the heat crosslinking agent (III) is an organic peroxide Plastic elastomeric composition;
( 2 ) The thermoplastic elastomer composition according to ( 1), wherein the crosslinking aid (IV) is glycerol dimethacrylate;
( 3 ) The thermoplastic elastomer composition according to (1) or (2), wherein the structural unit (a) derived from alkylstyrene is a structural unit derived from p-methylstyrene;
( 4 ) A molded article comprising the thermoplastic elastomer composition according to any one of (1) to ( 3 );
Is achieved by providing

  The thermoplastic elastomer composition of the present invention is excellent in flexibility, heat resistance such as strain recovery under high temperature conditions (for example, 120 ° C.), molding processability, and surface properties of the resulting molded body, and is effective for various applications. A molded product having a good surface appearance can be provided.

The present invention is described in detail below.
The addition polymerization block copolymer (I) constituting the thermoplastic elastomer composition of the present invention is mainly derived from an alkylstyrene having an aromatic vinyl compound unit and an alkyl group having 1 to 8 carbon atoms bonded to a benzene ring. At least one addition polymerization system selected from a block copolymer having a polymer block A containing 1% by mass or more of the structural unit (a), a polymer block B mainly composed of conjugated diene units, and a hydrogenated product thereof. It is a block copolymer.

  In the polymer block A, examples of the alkyl styrene that gives the structural unit (a) include o-alkyl styrene, m-alkyl styrene, p-alkyl styrene, 2, 4-dialkyl styrene, 3,5-dialkyl styrene, 2,4,6-trialkyl styrene, halogenated alkyl styrene in which one or more of the hydrogen atoms of the alkyl group in the aforementioned alkyl styrene is substituted with a halogen atom And so on. More specifically, examples of the alkylstyrene that gives the structural unit (a) include o-methylstyrene, m-methylstyrene, p-methylstyrene, 2,4-dimethylstyrene, 3,5-dimethylstyrene, 2, 4,6-trimethylstyrene, o-ethylstyrene, m-ethylstyrene, p-ethylstyrene, 2,4-diethylstyrene, 3,5-diethylstyrene, 2,4,6-triethylstyrene, o-propylstyrene, m-propylstyrene, p-propylstyrene, 2,4-dipropylstyrene, 3,5-dipropylstyrene, 2,4,6-tripropylstyrene, 2-methyl-4-ethylstyrene, 3-methyl-5 -Ethylstyrene, o-chloromethylstyrene, m-chloromethylstyrene, p-chloromethylstyrene, 2,4-bi (Chloromethyl) styrene, 3,5-bis (chloromethyl) styrene, 2,4,6-tri (chloromethyl) styrene, o-dichloromethylstyrene, m-dichloromethylstyrene, p-dichloromethylstyrene, etc. be able to.

  The polymer block A can have a unit derived from one or more of the alkyl styrene and the halogenated alkyl styrene described above as the structural unit (a). Among them, the structural unit (a) is a structural unit derived from p-methylstyrene, which is excellent in availability and reactivity with the crosslinking agent (III), and ensures a crosslinked structure in the polymer block A. It is preferable because it can be introduced. In addition, when carbon number of the alkyl group couple | bonded with the benzene ring of the structural unit (a) becomes 9 or more, it is inferior in the reactivity with the crosslinking agent (III), and it becomes difficult to form a crosslinked structure.

  The addition polymerization block copolymer (I) can have an aromatic vinyl compound unit other than the structural unit (a) as the aromatic vinyl compound unit constituting the polymer block A. Examples of other aromatic vinyl compound units other than the structural unit (a) include styrene, α-methylstyrene, β-methylstyrene, monofluorostyrene, difluorostyrene, monochlorostyrene, dichlorostyrene, methoxystyrene, vinylnaphthalene, and vinyl. Structural units derived from anthracene, indene, acetonaphthylene, and the like can be given, and one or more of these units can be included. Especially, as another aromatic vinyl compound unit, the structural unit derived from styrene is preferable.

  In the addition polymerization block copolymer (I), the polymer block A corresponds to the hard segment of the thermoplastic elastomer, and the alkyl group bonded to the benzene ring in the structural unit (a) reacts with the crosslinking agent to react with the heavy chain. It has a role of introducing a crosslink into the hard segment composed of the combined block A.

  The proportion of the structural unit (a) in the polymer block A is the mass of the polymer block A constituting the addition polymerization block copolymer (I) [the weight of the addition polymerization block copolymer (I) is 2 or more. When the combined block A is included, the total mass] is 1% by mass or more, more preferably 5% by mass or more, and further preferably 10% by mass or more. In some cases, all the units constituting the polymer block A may be composed of the structural unit (a). When the proportion of the structural unit (a) is less than 1% by mass, crosslinking is not sufficiently introduced into the polymer block A, and the resulting thermoplastic elastomer composition has heat resistance (for example, compression permanent at high temperature (120 ° C.)). The distortion is likely to be inferior. The bonding form of the structural unit (a) and the other aromatic vinyl compound unit in the polymer block A may be any form such as a random form, a block form, a tapered form, and a tapered block form.

  The polymer block A may have a small amount of structural units derived from other polymerizable monomers as necessary, together with the above-described aromatic vinyl compound unit containing the structural unit (a). In this case, the proportion of structural units derived from other polymerizable monomers is preferably 30% by mass or less, more preferably 10% by mass or less based on the total mass of the polymer block A. Examples of other polymerizable monomers in that case include 1-butene, pentene, hexene, butadiene, isoprene, and methyl vinyl ether. The bonding form of these other polymerizable monomers may be any form such as a random form, a block form, a tapered form, and a tapered block form.

  Next, in the addition polymerization block copolymer (I), the conjugated dienes constituting the polymer block B are isoprene, butadiene, hexadiene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene. And so on. The polymer block B may be composed of only one kind of these conjugated dienes or may be composed of two or more kinds. Among them, the polymer block B is composed of a structural unit derived from butadiene, isoprene, or a mixture of butadiene and isoprene. It is preferable. The type and content of the microstructure of the polymer block B are not particularly limited. In addition, when the polymer block B has a structural unit derived from two or more kinds of conjugated dienes, the bonding form thereof is random, block, tapered, or a combination of two or more thereof. be able to.

  The polymer block B may have a small amount of structural units derived from other polymerizable monomers as necessary, together with the structural units derived from the conjugated diene. The proportion of the other polymerizable monomer in that case is preferably 30% by mass or less based on the total mass of the polymer block B constituting the addition polymerization block copolymer (I), and is preferably 10% by mass. The following is more preferable. Examples of the other polymerizable monomer in that case include styrene, α-methylstyrene, the above-described alkylstyrene (preferably p-methylstyrene) that gives the structural unit (a), and the like.

  The polymer block B includes a polyisoprene block composed of isoprene units or a hydrogenated polyisoprene block in which part or all of carbon-carbon double bonds based on the isoprene units are hydrogenated; a polybutadiene block composed of butadiene units or the butadiene Hydrogenated polybutadiene block in which some or all of the carbon-carbon double bonds based on the unit are hydrogenated; or a copolymer block comprising a mixture of isoprene and butadiene comprising isoprene units and butadiene units, or the isoprene units and butadiene units It is a copolymer block composed of a mixture of isoprene and butadiene in which some or all of the carbon-carbon double bonds based on the above are hydrogenated, such as weather resistance and heat resistance of the thermoplastic elastomer composition of the present invention. It is preferable from the point.

In the above-described polyisoprene block that can be a constituent block of the polymer block B, before the hydrogenation, the unit derived from isoprene is a 2-methyl-2-butene-1,4-diyl group [—CH ₂ —C (CH ₃ ) ═CH—CH ₂ —; 1,4-bonded isoprene unit], isopropenyl ethylene group [—CH (C (CH ₃ ) ═CH ₂ ) —CH ₂ —; 3,4-bonded isoprene Unit] and 1-methyl-1-vinylethylene group [—C (CH ₃ ) (CH═CH ₂ ) —CH ₂ —; 1,2-bonded isoprene unit]. The ratio of each unit is not particularly limited.

In the above-mentioned polybutadiene block which can be a building block of the polymer block B, before hydrogenation, 70 to 20 mol%, particularly 65 to 40 mol% of the butadiene unit is a 2-butene-1,4-diyl group ( _{-CH 2 -CH = CH-CH 2} -; 1,4-bonded butadiene unit), 30 to 80 mol%, in particular 35 to 60 mol% ethylene vinyl group _{[-CH (CH = CH 2)} - CH _2- ; 1,2-bonded butadiene unit]. When the 1,4-bond amount in the polybutadiene block is within the range of 70 to 20 mol%, the rubber elasticity is improved.

  In the above-described copolymer block composed of a mixture of isoprene and butadiene which can be a building block of the polymer block B, the unit derived from isoprene is 2-methyl-2-butene-1,4-diyl before hydrogenation. Group, isopropenylethylene group and 1-methyl-1-vinylethylene group, and units derived from butadiene are composed of 2-butene-1,4-diyl group and vinylethylene group. The ratio is not particularly limited. In a copolymer block composed of a mixture of isoprene and butadiene, the arrangement of isoprene units and butadiene units may be random, block, or tapered. And in the copolymer block which consists of a mixture of isoprene and butadiene, it is preferable that the molar ratio of isoprene unit: butadiene unit is 10: 90-90: 10 from the point of the improvement effect of rubber elasticity, 30: 70- More preferably, it is 70:30.

  Carbon in the polymer block B of the addition polymerization block copolymer (I) from the viewpoint that the heat resistance and weather resistance of the thermoplastic elastomer composition containing the addition polymerization block copolymer (I) will be good. -Part or all of the carbon double bonds are preferably hydrogenated. In this case, the hydrogenation rate of the polymer block B composed of conjugated diene units is preferably 60 mol% or more, more preferably 80 mol% or more, and further preferably 95 mol% or more. Note that the hydrogenation rate of the carbon-carbon double bond based on the conjugated diene compound unit of the polymer block B is determined by the measurement means such as iodination titration, infrared spectrophotometer, nuclear magnetic resonance and the like before and after the hydrogenation reaction. The amount of the carbon-carbon double bond in the combined block B can be measured and calculated from the measured value. In particular, when the hydrogenation rate is close to 100 mol%, the reaction rate of the polymer block B and the crosslinking agent (III) is reduced when the thermoplastic elastomer composition of the present invention is produced, while the polymer block is reduced. The reaction between the structural unit (a) of A and the crosslinking agent (III) is promoted, so that the ratio of crosslinking introduced into the polymer block A forming the hard segment is increased.

  As long as the polymer block A and the polymer block B are bonded to the addition polymerization block copolymer (I), the bonding type is not limited and is linear, branched, radial, or those Any of two or more combined forms may be used. Among them, it is preferable that the bond form of the polymer block A and the polymer block B is a linear form, for example, when the polymer block A is represented by A and the polymer block B is represented by B. Further, a triblock copolymer represented by A-B-A, a tetrablock copolymer represented by A-B-A-B, a pentablock copolymer represented by A-B-A-B-A, etc. Can be mentioned. Among them, the triblock copolymer (ABA) is preferably used from the viewpoints of ease of production of the addition polymerization block copolymer (I) and flexibility.

  In the addition polymerization block copolymer (I), the number average molecular weight of the polymer block A is 2500 to 75000, preferably 5000 to 50000, and the number average molecular weight of the polymer block B is 10000 to 400000, preferably Is in the range of 30000-350,000, and the thermoplastic elastomer composition to be obtained has a number average molecular weight of the whole addition polymerization block copolymer (I) in the range of 12500-2000000, preferably 50000-1000000. From the viewpoints of the mechanical characteristics and molding processability, it is preferable. In addition, the number average molecular weight (Mn) as used in this specification says the value calculated | required from the standard polystyrene calibration curve by the gel permeation chromatography (GPC) method.

  Examples of the olefin resin (II) constituting the thermoplastic elastomer composition of the present invention include ethylene polymers, propylene polymers, poly (1-butene), poly (4-methyl-1-pentene) and the like. 1 type or 2 types or more can be used. Examples of the ethylene-based polymer include ethylene homopolymers such as high-density polyethylene, medium-density polyethylene, and low-density polyethylene, ethylene-butene-1 copolymer, ethylene-1-hexene copolymer, and ethylene-1-heptene. Copolymer, ethylene-1-octene copolymer, ethylene-4-methyl-1-pentene copolymer, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-acrylic acid ester copolymer , Ethylene-methacrylic acid copolymer, ethylene-methacrylic acid ester copolymer, and the like. Examples of the propylene polymer include propylene homopolymer, ethylene-propylene random copolymer, ethylene-propylene block copolymer, propylene-1-butene copolymer, propylene-ethylene-1-butene copolymer, propylene. Examples include -4-methylpentene-1 copolymer. Among these, from the viewpoint of molding processability, ethylene polymers such as high density polyethylene, medium density polyethylene, and low density polyethylene; propylene homopolymer, ethylene-propylene random copolymer, ethylene-propylene block copolymer, etc. The propylene-based polymer is preferable, and the propylene-based polymer is more preferable.

  Content of olefin resin (II) in the thermoplastic elastomer composition of this invention exists in the range of 10-300 mass parts with respect to 100 mass parts of addition polymerization type block copolymers (I), and is 15-200. The inside of the range of a mass part is preferable, and the inside of the range of 20-100 mass parts is more preferable. If the ratio of the olefin resin (II) to 100 parts by mass of the addition polymerization block copolymer (I) is less than 10 parts by mass, the molding processability of the resulting thermoplastic elastomer composition becomes poor, while it exceeds 300 parts by mass. And the softness | flexibility and rubber elasticity of the thermoplastic elastomer composition which are obtained will fall.

  The crosslinking agent (III) in the present invention is present in the polymer block A of the addition polymerization block copolymer (I) during the heat treatment under melting conditions when obtaining the thermoplastic elastomer composition of the present invention. A crosslinking agent that acts on the structural unit (a) to form a crosslink in the polymer block A at that portion is used. Depending on the conditions during the heat treatment (for example, treatment temperature, treatment time, etc.), an appropriate crosslinking agent can be selected in consideration of reactivity and the like. Among them, one or more organic peroxides are crosslinked. It is preferably used as the agent (III).

  Examples of the crosslinking agent (III) include dicumyl peroxide, di-t-butyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, 2,5-dimethyl-2,5-di ( t-butylperoxy) hexyne-3, 1,3-bis (t-butylperoxyisopropyl) benzene, 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane, n-butyl-4, 4-bis (t-butylperoxy) valerate, benzoyl peroxide, p-chlorobenzoyl peroxide, 2,4-dichlorobenzoyl peroxide, t-butylperoxybenzoate, t-butylperoxyisopropyl carbonate, diacetyl peroxide, lauroyl peroxide, t-butyl Such as cumyl peroxide . These may be used individually by 1 type, or may use 2 or more types. Among these, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane and dicumyl peroxide are preferably used from the viewpoint of reactivity.

  The amount of the crosslinking agent (III) used is in the range of 0.01 to 20 parts by mass and in the range of 0.01 to 5 parts by mass with respect to 100 parts by mass of the addition polymerization block copolymer (I). preferable. When the amount of the crosslinking agent (III) used is less than 0.01 parts by mass, sufficient crosslinking cannot be formed. On the other hand, when the amount is more than 20 parts by mass, the rubber softener (V) Bleed out, deterioration of mechanical properties, etc. occur.

  In the present invention, 0.5 to 50 mass of the crosslinking aid (IV) having two or more methacryloyl groups and other functional groups with respect to 100 mass parts of the addition polymerization block copolymer (I). Use parts. By using the crosslinking aid (IV) at such a ratio, an appropriate degree of crosslinking can be obtained, and a molded article having excellent surface recovery and excellent strain recovery at high temperatures, rubbery properties, and extrusion properties. A thermoplastic elastomer composition can be obtained. When the amount of the crosslinking aid (IV) used is less than 0.5 parts by mass with respect to 100 parts by mass of the addition polymerization block copolymer (I), the degree of crosslinking of the resulting thermoplastic elastomer composition is insufficient. Thus, the strain recovery property at high temperature is inferior, and if it exceeds 50 parts by mass, the resulting elastomeric elastomer composition lacks the flexible rubber-like properties. The amount of the crosslinking aid (IV) used is within the range of 0.5 to 20 parts by mass with respect to 100 parts by mass of the addition polymerization block copolymer (I) from the viewpoint of molding processability and flexibility. Preferably, the range of 1-15 mass parts is more preferable.

  Examples of functional groups other than the methacryloyl group possessed by the crosslinking aid (IV) include hydroxyl group, amino group, epoxy group, fluoro group, and silyl group. From the viewpoint of availability, hydroxyl group, amino group, epoxy Group is preferred, and a hydroxyl group is more preferred. As the crosslinking aid (IV), a partial methacrylic acid ester of a trivalent or higher alcohol is preferably used from the viewpoint of strain recovery at a high temperature and the surface property of the molded article. As the trivalent or higher alcohol, glycerin ( Glycerol), trimethylolpropane, pentaerythritol, diglycerin, ditrimethylolpropane, dipentaerythritol and the like, and trivalent or higher alcohols having 3 to 12 carbon atoms.

  Examples of the crosslinking aid (IV) include glycerol dimethacrylate, trimethylolpropane dimethacrylate, pentaerythritol dimethacrylate, pentaerythritol trimethacrylate, ditrimethylolpropane dimethacrylate, ditrimethylolpropane trimethacrylate, dipentaerythritol dimethacrylate, Pentaerythritol trimethacrylate, pentaerythritol tetramethacrylate, dipentaerythritol pentamethacrylate, serinol dimethacrylate, 2-amino-2-methyl-1,3-propanediol dimethacrylate, 3-amino-1,2-propanediol dimethacrylate 1-oxiranyl-1,2-ethanediol dimethacrylate, 2,2,2-trifluoroe 1,1-diol dimethacrylate, 2,2,3,3,3-pentafluoro-1,1-propanediol dimethacrylate, 2,2,3,3-tetrafluoro-1,4-butanediol Methacrylate, methyl (3,3,3-trifluoropropyl) silanediol dimethacrylate, and the like. Among these, glycerol dimethacrylate is preferable from the viewpoint of strain recovery at high temperatures and surface properties of molded products.

The thermoplastic elastomer composition of the present invention may contain a rubber softener (V) as necessary. Rubber softeners (V) include petroleum-based softeners such as paraffinic and naphthenic process oils; liquid paraffin; vegetable oil-based softeners such as peanut oil and rosin; ethylene-α-olefin oligomers, liquid polybutenes, low Examples include synthetic softeners such as molecular weight polybutadiene. As the rubber softener (V), a softener having a kinematic viscosity of 20 to 800 mm ² / s at 40 ° C., particularly paraffinic oil is preferable. These rubber softeners (V) can be used alone or in combination of two or more. Examples of the rubber softener (V) that can be suitably used in the present invention include paraffinic process oils in the product name “Diana Process Oil” series marketed by Idemitsu Kosan Co., Ltd.

  The content of the rubber softener (V) in the thermoplastic elastomer composition of the present invention is in the range of 0 to 300 parts by mass with respect to 100 parts by mass of the addition polymerization block copolymer (I). The inside of the range of 250 mass parts is preferable, and the inside of the range of 50-200 mass parts is more preferable. When the content of the rubber softening agent (V) exceeds 300 parts by mass with respect to 100 parts by mass of the addition polymerization block copolymer (I), the mechanical properties of the resulting thermoplastic elastomer composition deteriorate, Bleed-out of the rubber softener (V) from the molded product obtained from such a thermoplastic elastomer composition becomes remarkable.

  The thermoplastic elastomer composition of the present invention can contain other polymers as long as the effects of the present invention are not impaired. Examples of other polymers that can be contained include polyphenylene ether resins; polyamide 6, polyamide 6 · 6, polyamide 6 · 10, polyamide 11, polyamide 12, polyamide 6 · 12, polyhexamethylenediamine terephthalamide, polyhexamethylene Polyamide resins such as diamine isophthalamide and xylene group-containing polyamide; Polyester resins such as polyethylene terephthalate and polybutylene terephthalate; Acrylic resins such as polymethyl acrylate and polymethyl methacrylate; Polyoxymethylene homopolymer, Polyoxymethylene Polyoxymethylene resins such as copolymers; Styrene homopolymers, styrene resins such as acrylonitrile / styrene resins and acrylonitrile / butadiene / styrene resins; polycarbonates Fat; ethylene / propylene copolymer rubber (EPM), ethylene / propylene / non-conjugated diene copolymer rubber (EPDM); styrene / butadiene copolymer rubber, styrene / isoprene copolymer rubber or hydrogenated product thereof or modified product thereof Natural rubber; synthetic isoprene rubber, liquid polyisoprene rubber and its hydrogenated product or modified product; chloroprene rubber; acrylic rubber; butyl rubber; acrylonitrile-butadiene rubber; epichlorohydrin rubber; silicone rubber; fluorine rubber; Examples include urethane rubber; polyurethane elastomer; polyamide elastomer; polyester elastomer; soft vinyl chloride resin. The content of these other polymers is preferably within a range in which the mechanical properties of the resulting thermoplastic elastomer composition are not impaired, and 200 parts by mass or less with respect to 100 parts by mass of the addition polymerization block copolymer (I). Is preferred.

  Moreover, the thermoplastic elastomer composition of this invention can contain an inorganic filler as needed. Examples of the inorganic filler include calcium carbonate, talc, clay, synthetic silicon, titanium oxide, carbon black, barium sulfate, mica, glass fiber, whisker, carbon fiber, magnesium carbonate, glass powder, metal powder, kaolin, graphite, two Examples thereof include molybdenum sulfide and zinc oxide, and one or more of these can be contained. The content of the inorganic filler is preferably within a range where the effects of the present invention are not impaired, generally 50 parts by mass or less with respect to 100 parts by mass of the thermoplastic elastomer composition.

  Further, the thermoplastic elastomer composition of the present invention is optionally provided with a reinforcing resin such as α-methylstyrene resin, a flame retardant, a lubricant, a light stabilizer, a pigment, a heat stabilizer, an antifogging agent, an antistatic agent, and silicone. It can contain 1 type (s) or 2 or more types, such as oil, an antiblocking agent, a ultraviolet absorber, a heat stabilizer, antioxidant, and a coloring agent. Among these, examples of the antioxidant include hindered phenol-based, hindered amine-based, phosphorus-based, and sulfur-based antioxidants.

The thermoplastic elastomer composition of the present invention comprises an addition polymerization block copolymer (I), an olefin resin (II), a crosslinking agent (III), a crosslinking aid (IV) and optionally a rubber softener ( V) and, if necessary, a method of heat treating other components all at once under a melting condition in a single step; addition polymerization block copolymer (I), olefin resin (II), crosslinking aid (IV ), Optionally a rubber softener (V), and if necessary, all other components are kneaded under melting conditions and then added by a crosslinking agent (III) and heat-treated under the melting conditions. be able to.
The method for heat treatment under the melting conditions in the present invention is not particularly limited as long as it is a method for heating the above components at least under the condition that the olefin resin (II) is melted. A method of heating while applying shear stress by kneading is preferred.

  As a device for heat treatment under melting conditions for producing the thermoplastic elastomer composition of the present invention, any melt kneading device capable of uniformly mixing each component can be used, for example, a single screw extruder, twin screw Examples thereof include melt kneaders such as an extruder, a Banbury mixer, a heating roll, and various kneaders. Among them, it is preferable to use a twin-screw extruder from the viewpoint that the shearing force during kneading is large so that it can be dispersed finely and uniformly, and continuous operation is possible.

  Although not limited at all, when the thermoplastic elastomer composition of the present invention is produced using a single-screw extruder or a twin-screw extruder, each component can be added even if one extruder is used. In order to disperse, heat treatment (preferably melt-kneading) may be performed step by step using two or more extruders. The heat treatment temperature can be appropriately selected within a temperature range in which at least the olefin resin (II) melts and the addition polymerization block copolymer (I) reacts with the crosslinking agent (III), and usually ranges from 140 to 270 ° C. The inside is preferable, and the inside of the range of 160 to 240 ° C. is more preferable. The heat treatment time is preferably 30 seconds to 5 minutes, and more preferably 45 seconds to 3 minutes.

  The thermoplastic elastomer composition thus obtained has thermoplasticity and can be molded by known methods such as extrusion molding, injection molding, press molding, calendar molding, and the like. It can also be compounded with other members (for example, polymer materials such as polyethylene, polypropylene, olefin elastomer, ABS resin, polyamide, metal, wood, cloth, etc.) by a two-color molding method.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited at all by these Examples. The thermoplastic elastomer compositions obtained in the following examples and comparative examples were evaluated as follows.

[1] Hardness (JIS-A)
The thermoplastic elastomer compositions obtained in Examples or Comparative Examples were injection molded at 230 ° C. to obtain a sheet having a length of 110 mm × width of 110 mm × thickness of 2 mm. Six sheets were stacked to a thickness of 12 mm, and the A hardness was measured according to JIS K 6253.

[2] Compression set A sheet having a length of 110 mm, a width of 110 mm and a thickness of 2 mm was obtained by injection molding of the thermoplastic elastomer composition obtained in the examples or comparative examples at 230 ° C. Six sheets of this sheet are stacked and placed in a frame of φ29 mm × 12.5 mm, pressed at 200 ° C. for 5 minutes, and then in accordance with JIS K 6262 at a temperature of 120 ° C. and 70 ° C. with a compression deformation of 25% The compression set after standing for 22 hours was measured. The smaller this value, the better the strain recovery at high temperatures.

[3] Appearance of molded product (surface properties)
The thermoplastic elastomer compositions obtained in the following Examples and Comparative Examples were subjected to a temperature condition of 180 ° C. using a 40φ single screw extruder having a slit die having a width of 30 mm × a thickness of 2.2 mm attached to the outlet portion. Was extruded to obtain a ribbon-shaped molded body, and the surface properties of the molded body at that time were visually evaluated according to the following criteria.
○: The surface is smooth ×: The surface is rough

[4] Stickiness of molded article Using thermoplastic elastomer compositions obtained in the following examples and comparative examples, using a 40φ single screw extruder in which a slit die having a width of 30 mm × a thickness of 2.2 mm was attached to the outlet portion. The ribbon-shaped molded body was obtained by extrusion molding at a temperature of 180 ° C., and the stickiness of the molded body surface at that time was evaluated according to the following criteria.
○: Bleed or bloom of low molecular weight material is not seen and sticky even when touched by hand ×: Bleed or bloom of low molecular weight material is seen or sticky when touched by hand

  The contents of the addition polymerization block copolymers, olefin resins, crosslinking agents and crosslinking aids, and rubber softeners used in the following Examples or Comparative Examples are as follows.

Production Example 1: Addition-polymerized block copolymer (I)
In a pressure vessel equipped with a stirrer, 30 kg of cyclohexane, 14 ml of sec-butyllithium (1.3 M cyclohexane solution) and 778 g of a mixture of p-methylstyrene / styrene = 30/70 (mass ratio) are added and polymerized at 50 ° C. for 120 minutes. Then, 3630 g of a mixture of isoprene / butadiene = 60/40 (mass ratio) was added and polymerized for 120 minutes. Thereafter, 778 g of a mixture of p-methylstyrene / styrene = 30/70 (mass ratio) was further added, polymerization was performed for 120 minutes, methanol was added to stop the polymerization, and poly (p-methylstyrene / styrene) -poly A reaction mixture containing (isoprene / butadiene) -poly (p-methylstyrene / styrene) triblock copolymer was obtained. A hydrogenation catalyst prepared from nickel octylate and triisopropylaluminum was added to the resulting reaction mixture, and a hydrogenation reaction was performed in a hydrogen atmosphere at 80 ° C. and 1 MPa for 5 hours to obtain poly (p-methylstyrene / styrene). ) -Poly (isoprene / butadiene) -poly (p-methylstyrene / styrene) triblock copolymer hydrogenated product [hereinafter referred to as addition polymerization block copolymer (I)] was obtained. The resulting addition polymerization block copolymer (I) has a Mn of 360,000, the ratio of each polymer block is 15/70/15 (mass ratio), and the hydrogenation rate of the poly (isoprene / butadiene) block is 99 mol%. Met.

Production Example 2: Addition-polymerized block copolymer (1)
In a pressure vessel equipped with a stirrer, 30 kg of cyclohexane and 20 ml of a 1.3M cyclohexane solution of sec-butyllithium were added, and 778 g of styrene was added over 30 minutes to polymerize at 50 ° C. for 120 minutes, and isoprene / butadiene = 60 / 30 (mass ratio) mixture 3630 g was added over 60 minutes and polymerized at the same temperature for 120 minutes, and styrene 778 g was further added over 30 minutes and polymerized at the same temperature for 120 minutes to obtain polystyrene-poly (isoprene / A reaction mixture containing a butadiene) -polystyrene triblock copolymer was obtained. A hydrogenation catalyst prepared from nickel octylate and triisopropylaluminum was added, a hydrogenation reaction was carried out in a hydrogen atmosphere at 80 ° C. and 1 MPa for 5 hours, and a hydrogenated product of the polystyrene-polybutadiene-polystyrene triblock copolymer described above. [Hereinafter referred to as addition polymerization block copolymer (1)]. The resulting addition polymerization block copolymer (1) has a Mn of 360,000, the ratio of each polymer block is 15/70/15 (mass ratio), and the hydrogenation rate of the poly (isoprene / butadiene) block is 99 mol%. Met.

Olefin resin:
(II): homopolymerized polypropylene (homopolymer) [manufactured by Prime Polymer Co., Ltd., trade name “Prime Polypro E111G”, MFR: 0.5 g / 10 min (230 ° C., 21 N)]
Cross-linking agent:
(III): 2,5-Dimethyl-2,5-di (t-butylperoxy) hexane [Nippon Yushi Co., Ltd., trade name “Perhexa 25B-40”]
Crosslinking aid:
(IV): Glycerol dimethacrylate [manufactured by Shin-Nakamura Chemical Co., Ltd., trade name “NK ester 701”]
(1): Trimethylolpropane trimethacrylate [made by Shin-Nakamura Chemical Co., Ltd., trade name “NK ester TMPT”]
(2): triallyl isocyanurate [manufactured by Nippon Kasei Co., Ltd., trade name “TAIC WH-60”]
(3): Hexanediol dimethacrylate [manufactured by Shin-Nakamura Chemical Co., Ltd., trade name “NK Ester HD-N”]
(4): Polyethylene glycol dimethacrylate (n = 1) [manufactured by Shin-Nakamura Chemical Co., Ltd., trade name “NK Ester 1G”]
(5): Polyethylene glycol dimethacrylate (n = 2) [manufactured by Shin-Nakamura Chemical Co., Ltd., trade name “NK ester 2G”]
(6): Polyethylene glycol dimethacrylate (n = 3) [manufactured by Shin-Nakamura Chemical Co., Ltd., trade name “NK Ester 3G”]
Rubber softener:
(V) -1: Paraffinic process oil [manufactured by Idemitsu Kosan Co., Ltd., trade name “PW-380”, kinematic viscosity: 381.6 mm ² / s (40 ° C.)]
(V) -2: Paraffin-based process oil [manufactured by Idemitsu Kosan Co., Ltd., trade name “PW-90”, kinematic viscosity: 95.54 mm ² / s (40 ° C.)]
Lubricant:
Unsaturated fatty acid amide [Nippon Kasei Co., Ltd., trade name "Diamid O-200"]

Examples 1-4, Comparative Examples 1-7
(1) The ratio (all parts by mass) of the addition polymerization block copolymer, olefin resin, crosslinking agent, crosslinking aid and rubber softener produced in Production Example 1 or 2 shown in Table 1 or 2 below. ), Respectively, and then fed to a twin-screw extruder [manufactured by Nippon Steel Works, Ltd.], melt-kneaded for 1 minute at a temperature of 160 to 200 ° C. and a rotation speed of 300 rpm, and hot cut. A pellet-shaped thermoplastic elastomer composition was produced.
(2) Using the pellets of the thermoplastic elastomer composition obtained in (1) above, using an injection molding machine (“IS-55EPN” manufactured by Toshiba Machine Co., Ltd., mold clamping pressure 55 × 10 ³ kg), Injection molding was performed under the conditions of a melting temperature of 230 ° C. and a mold temperature of 40 ° C. to produce a sheet-like molded product of length × width × thickness = 110 mm × 110 mm × 2 mm. The physical properties of the molded product were measured by the methods described above, and the results were as shown in Table 1 and Table 2 below.

As is clear from Tables 1 and 2, the thermoplastic elastomer compositions of Examples 1 to 4 that satisfy the requirements of the present invention are excellent in compression set at 70 ° C. and 120 ° C. and surface properties at any hardness. Has given a very good molded product.
On the other hand, from the results of Table 2, in the case of Comparative Examples 1 to 6 using the crosslinking aids (1) to (6) that do not satisfy the requirements of the present invention, the surface properties of the obtained molded products are obtained. It turns out that it is inferior. Moreover, in the case of the comparative example 7 using the block copolymer (1) which does not have the structural unit (a) derived from alkyl styrene as an addition polymerization type block copolymer, compared with the case of Example 4. In particular, it can be seen that the compression set at 120 ° C. is large and the strain recovery at a high temperature is extremely poor.

  The thermoplastic elastomer composition of the present invention provides a molded article having excellent strain recovery at high temperatures (heat resistance), extrusion processability, and excellent surface properties. Therefore, a sheet, film, plate, tube, Applications such as hoses and belts; footwear applications such as sports shoes and fashion sandals; household appliances applications such as televisions, stereos, vacuum cleaners and refrigerators; building materials applications such as sealing packings used on doors and window frames of buildings; bumpers It can be effectively used in a wide range of applications such as parts, body panels, weatherstrips, grommets and other automotive exterior parts; various grips in scissors, drivers, toothbrushes, ski stocks, etc.

Claims (4)

From a polymer block A mainly containing an aromatic vinyl compound unit and containing 1% by mass or more of a structural unit (a) derived from alkylstyrene having an alkyl group having 1 to 8 carbon atoms bonded to a benzene ring, and a conjugated diene unit The olefin resin (II) 10 to 100 parts by mass of at least one addition polymerization block copolymer (I) selected from a block copolymer having a main polymer block B and a hydrogenated product thereof. 300 parts by weight, crosslinking agent (III) 0.01-20 parts by weight, crosslinking aid (IV) 0.5-50 parts by weight having two or more methacryloyl groups and hydroxyl groups, and rubber softener (V) A thermoplastic elastomer composition obtained by heat-treating 30 to 250 parts by mass under melting conditions , wherein the crosslinking agent (III) is an organic peroxide. Lastomer composition . The thermoplastic elastomer composition according to claim 1, wherein the crosslinking aid (IV) is glycerol dimethacrylate. The thermoplastic elastomer composition according to claim 1 or 2, wherein the structural unit (a) derived from alkylstyrene is a structural unit derived from p-methylstyrene. A molded article comprising the thermoplastic elastomer composition according to any one of claims 1 to 3 .