JP6425477B2 - Thermoplastic elastomer composition - Google Patents

Description

The present invention relates to a thermoplastic elastomer composition. More specifically, flexibility, heat-resistant oil (oil resistance at high temperature), heat distortion characteristics (compression set resistance at high temperature), mechanical properties, compatibility, bleed resistance, manufacturability of composition, and injection moldability The present invention relates to an excellent thermoplastic elastomer composition.

In recent years, it is a soft material having rubber elasticity, which does not require a vulcanization process, and a thermoplastic elastomer having the same molding processability and material recyclability as a thermoplastic resin substitutes for a vulcanized rubber as an automotive material. It is widely used in the fields of parts, home appliance parts, electric wire coating, medical parts, footwear, and sundries.

Polyester-based thermoplastic elastomers are used for automobile CVJ boots and the like because they are excellent in flex fatigue resistance, heat resistance and oil resistance. However, polyester-based thermoplastic elastomers are expensive compared to vulcanized rubber; require drying prior to molding; low flexibility, weatherability, compression set resistance, and hydrolysis resistance; And the specific gravity is large and heavier than the vulcanized rubber;

Thermoplastic polystyrene-based thermoplastic elastomers such as hydrogenated products of styrene-butadiene block copolymer and hydrogenated products of styrene-isoprene block copolymer have flexibility, rubber elasticity at normal temperature, heat aging resistance (heat stability), weather resistance It has excellent properties and moldability and is widely used. On the other hand, polystyrene-based thermoplastic elastomers have problems such as oil resistance, compression set resistance and low rubber elasticity at high temperatures as compared with vulcanized rubber. Therefore, materials obtained by dynamically crosslinking a composition containing a hydrogenated substance such as a styrene-butadiene block copolymer are proposed as techniques for solving these problems (for example, Patent Documents 1 to 5). ). However, the above materials have a problem that the balance between flexibility and high temperature, especially compression set resistance characteristics at 100 ° C. or higher and oil resistance are low; and mechanical strength is low, and they are satisfactory as a substitute for vulcanized rubber. It can not be

Many thermoplastic elastomer compositions obtained by dynamically crosslinking polyolefin resins and polyolefin copolymer rubbers are also known. For example, an elastomer composition in which an ethylene-based copolymer resin such as ethylene-vinyl acetate copolymer and a rubber such as a halogenated butyl rubber are dynamically crosslinked has been disclosed (Patent Document 6). This composition is excellent in heat shrinkage resistance and molding processability, but is inferior in balance between flexibility and compression set resistance at high temperature and oil resistance. There is also disclosed a dynamically vulcanized thermoplastic elastomer composition comprising a polyolefin such as ethylene-vinyl acetate copolymer, a monoolefin rubber such as EPDM, a conjugated diene polymer such as a nitrile rubber, and a process oil (patent document 7). This composition is very soft but is inferior in moldability, and is insufficient in compression set characteristics at high temperatures and oil resistance.

JP-A-59-6236 Japanese Patent Application Laid-Open No. 63-57662 Japanese Examined Patent Publication No. 3-49927 Japanese Examined Patent Publication 3-11291 Japanese Examined Patent Publication 6-13628 JP-A-61-26641 Japanese Patent Application Laid-Open No. 9-291176

The objects of the present invention are: flexibility, heat resistant oil (oil resistance at high temperature), heat distortion property (compression set resistance at high temperature), mechanical properties, compatibility, bleed resistance, manufacturability of composition, and injection An object of the present invention is to provide a thermoplastic elastomer composition excellent in moldability.

As a result of intensive studies, the present inventor has found that the above-mentioned problems can be achieved by a specific thermoplastic elastomer composition containing a copolymer rubber of an unsaturated nitrile and a conjugated diene.

That is, the present invention
(A) 100 parts by mass of copolymer rubber of unsaturated nitrile and conjugated diene;
(B) polypropylene resin 10 to 150 parts by mass;
(C) Softener 20 to 160 parts by mass;
(D) At least one selected from the group consisting of block copolymers of aromatic vinyl compounds and conjugated diene compounds, and hydrogenated products of block copolymers of aromatic vinyl compounds and conjugated diene compounds Parts by mass; and
(E) organic peroxide 0.5 to 2.5 parts by mass;
And (c) the softener comprises
(C-1) Softener for non-aromatic rubber 40 to 80% by mass; and (c-2) polar plasticizer 60 to 20% by mass;
The thermoplastic elastomer composition is characterized in that the sum of the component (c-1) and the component (c-2) is 100% by mass.

In the second invention, the (c-2) polar plasticizer is phthalic acid ester plasticizer, phosphoric acid ester plasticizer, adipic acid ester plasticizer, trimellitic acid ester plasticizer, polyester plasticizer Epoxy plasticizers, sebacate ester plasticizers, azelaic acid ester plasticizers, citric acid ester plasticizers, glycolic acid plasticizers, ricinoleic acid plasticizers, maleic acid ester plasticizers, fumaric acid ester plasticizers It is one or more selected from the group consisting of plasticizers, pyromellitic acid ester plasticizers, itaconic acid ester plasticizers, and cyclohexane dicarboxylate plasticizers, as described in the first invention. It is a thermoplastic elastomer composition.

A third invention is characterized in that the (c-1) non-aromatic softening agent for rubber is at least one selected from the group consisting of paraffin oil and naphthene oil. It is a thermoplastic elastomer composition as described in 2 invention.

A fourth invention is the thermoplastic elastomer composition according to any one of the first to third inventions, which is melt-kneaded at a temperature equal to or higher than the one-minute half-life temperature of the (e) organic peroxide. Manufacturing method.

A fifth invention is an article comprising the thermoplastic elastomer composition according to any one of the first to third inventions.

A sixth invention is an article comprising the thermoplastic elastomer composition produced by the method according to the fourth invention.

The thermoplastic elastomer composition of the present invention is flexible, heat resistant oil (oil resistance at high temperature), heat distortion characteristics (compression set resistance at high temperature), mechanical properties, compatibility, bleed resistance, and composition production. It is excellent in the properties and the injection moldability. Therefore, as a material which substitutes a vulcanized rubber, it can be used suitably for an automobile part, a household appliance part, electric wire coating, medical parts, footwear, miscellaneous goods, etc. In particular, they are useful as materials for automobile parts such as fuel tubes, diaphragms, boots for joints, packings, and O-rings.

(A) Copolymer rubber of unsaturated nitrile and conjugated diene:
The thermoplastic elastomer composition of the present invention comprises component (a) a copolymer rubber of unsaturated nitrile and conjugated diene. Component (a) plays an important role in heat-resistant oil (oil resistance at high temperature) and heat distortion characteristics (compression set resistance at high temperature).

The component (a) is not particularly limited, and those obtained by copolymerizing an arbitrary unsaturated nitrile and an arbitrary conjugated diene by a known method such as emulsion polymerization can be used. Also, if desired, monomers other than unsaturated nitrile and conjugated diene may be used.

The unsaturated nitrile is a polymerizable monomer having a polymerizable carbon-carbon double bond and a nitrile group (cyano group) in one molecule. Examples of unsaturated nitriles include (meth) acrylonitrile compounds such as acrylonitrile, methacrylonitrile, α-ethyl acrylonitrile, methyl α-isopropyl acrylonitrile, methyl α-n-butyl acrylonitrile and the like; 2-cyanoethyl (meth) acrylate, 2- (2-cyanoethoxy) ethyl (meth) acrylate, 3- (2-cyanoethoxy) propyl (meth) acrylate, 4- (2-cyanoethoxy) butyl (meth) acrylate, 2- [2- (2-cyanoethoxy) And the like) cyano group-containing (meth) acrylic acid ester compounds such as ethoxy) ethyl (meth) acrylate; fumaronitrile; and 2-methylene glutaronitrile. Among these, acrylonitrile is preferred. As unsaturated nitriles, one or more of these can be used in combination.

In the present specification, (meth) acrylate means acrylate or methacrylate. (Meth) acrylonitrile means acrylonitrile or methacrylonitrile.

The content of the structural unit derived from the unsaturated nitrile in the component (a) (hereinafter sometimes abbreviated as a nitrile content) is not particularly limited, but is preferably 25 from the viewpoint of heat resistance oil and heat distortion characteristics. It is at least 30% by mass, more preferably at least 30% by mass. Further, from the viewpoint of flexibility, it is preferably 70% by mass or less, more preferably 50% by mass or less. The nitrile content is more preferably 30 to 50% by mass. When the nitrile content is in the above-mentioned range, it is possible to obtain a thermoplastic elastomer composition in which the balance between the flexibility and the heat-resistant oil and heat-resistant strain characteristics is very excellent.

The conjugated diene is a polymerizable monomer having a structure in which two carbon-carbon double bonds are linked by one carbon-carbon single bond. As a conjugated diene, for example, 1,3-butadiene, isoprene (2-methyl-1,3-butadiene), 2,3-dimethyl-1,3-butadiene, chloroprene (2-chloro-1,3-butadiene) And so on. Among these, 1,3-butadiene and isoprene are preferred. As conjugated dienes, one or more of these may be used in combination.

The content of the structural unit derived from the conjugated diene in the component (a) (hereinafter sometimes referred to as a diene content) is not particularly limited, but from the viewpoint of flexibility, preferably 30% by mass or more, more preferably Preferably it is 50 mass% or more. Further, from the viewpoint of heat resistant oil and heat distortion characteristics, the content is preferably 75% by mass or less, more preferably 70% by mass or less.

The other monomer is not particularly limited as long as it is a monomer copolymerizable with the saturated nitrile and the conjugated diene, and any monomer can be used. Other monomers include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, tert- Alkyl (meth) acrylate compounds such as butyl (meth) acrylate, n-hexyl (meth) acrylate and 2-ethylhexyl (meth) acrylate; 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 2 -Alkoxyalkyl (meth) acrylated such as methoxypropyl (meth) acrylate, 2-ethoxypropyl (meth) acrylate, 3-methoxypropyl (meth) acrylate and 3-ethoxypropyl (meth) acrylate Polymerizable compounds having a carboxyl group and a carbon-carbon double bond, such as acrylic acid, methacrylic acid, itaconic acid, and β-carboxyethyl (meth) acrylate; and aromatic vinyl compounds such as styrene Can. As other monomers, these 1 type, or 2 or more types can be used in combination.

The content of the structural unit derived from the other monomer in the component (a) is usually 30% by mass or less, preferably 20% by mass or less, from the viewpoint of the balance between flexibility and heat-resistant oil and heat distortion characteristics. Preferably it is 10 mass% or less.

Examples of the component (a) include acrylonitrile-butadiene copolymer rubber (NBR), acrylonitrile-butadiene-isoprene copolymer rubber (NBIR), acrylonitrile-isoprene copolymer rubber (NIR), acrylonitrile-butadiene-butoxy Acrylate copolymer rubber, acrylonitrile-butadiene-acrylic acid copolymer rubber, acrylonitrile-butadiene-methacrylic acid copolymer rubber and the like can be mentioned. Among these, acrylonitrile-butadiene copolymer rubber (NBR) is preferable from the viewpoint of heat and oil resistance. As the component (a), a mixture of one or more of these can be used.

The component (a) uses an L-shaped rotor according to JIS K 6300-1-2013 from the viewpoint of heat distortion resistance, flexibility, and formability, preheating time 1 minute, rotor rotation time 4 minutes, and testing The Mooney viscosity (ML (1 + 4) 100 ° C.) measured under the conditions of a temperature of 100 ° C. is preferably 20 to 120, more preferably 40 to 100.

(B) Polypropylene resin:
The thermoplastic elastomer composition of the present invention comprises component (b) a polypropylene resin. The component (b) has the effect of controlling the flowability of the composition at the time of melt-kneading to well disperse the rubber component such as the component (a).

As said component (b), for example, a propylene homopolymer; propylene and other small amounts of α-olefins (eg, ethylene, 1-butene, 1-hexene, 1-octene, 4-methyl-1-pentene, etc. And copolymers thereof (including block copolymers and random copolymers); and the like. As the component (b), a mixture of one or more of them can be used.

From the viewpoint of formability, the component (b) preferably has a melt mass flow rate of 0.1 to 100 g / 10 min measured under the conditions of 230 ° C. and 21.18 N according to JIS K 7210-1999. .

The component (b) is held at 230 ° C. for 5 minutes and cooled to −10 ° C. at 10 ° C./minute using a Diamond DSC type differential scanning calorimeter from Perkin Elmer Japan Co., Ltd. Peak that appears on the highest temperature side in a second melting curve (melting curve measured in the last heating step) measured by a program held at -10 ° C for 5 minutes and heated to 230 ° C at 10 ° C / min The peak top melting point of is preferably 150 ° C. or more, more preferably 160 ° C. or more. The upper limit of the peak top melting point is not particularly limited, but is at most 167 ° C. because it is a polypropylene resin.

The compounding amount of the component (b) is preferably 10 parts by mass or more, preferably 100 parts by mass of the component (a), in view of mechanical properties, compatibility, manufacturability of the composition, and injection moldability. 20 parts by mass or more. It is 150 parts by mass or less, preferably 125 parts by mass or less, from the viewpoint of flexibility, heat distortion resistance, and heat and oil resistance. More preferably, it is 20 to 125 parts by mass. When the content of the component (b) is in the above range, it is possible to obtain a thermoplastic elastomer composition in which the balance between the flexibility and the heat resistant oil property or the heat resistant strain property is very excellent.

(C) Softener:
The thermoplastic elastomer composition of the present invention comprises component (c) a softener. Component (c) plays an important role in improving the balance between the flexibility and the heat-resistant oil and heat-resistant strain characteristics.

The component (c) comprises (c-1) 40 to 80% by mass of a non-aromatic softener for rubber, and (c-2) 60 to 20% by mass of a polar plasticizer. Here, the sum of component (c-1) and component (c-2) is 100% by mass. Component (c-1) is at most 80% by mass, preferably at most 70% by mass (component (c-2) is at least 20% by mass, preferably at least 30% by mass); A plasticizing elastomeric composition can be obtained. When the component (c-1) is 40% by mass or more, preferably 50% by mass or more (the component (c-2) is 60% by mass or less, preferably 50% by mass or less), the thermoplastic elastomer having good heat and oil resistance A composition can be obtained. The component (c) more preferably comprises 50 to 70% by mass of the component (c-1) and 50 to 30% by mass of the component (c-2). When the ratio of the component (c-1) to the component (c-2) is in the above range, it is possible to obtain a thermoplastic elastomer composition having an extremely excellent balance of flexibility, heat-resistant oil and bleed resistance. .

The compounding amount of the component (c) is 20 parts by mass or more, preferably 40 parts by mass or more, from the viewpoint of flexibility and heat-resistant oil, with respect to 100 parts by mass of the component (a). It is 160 parts by mass or less, preferably 125 parts by mass or less, from the viewpoints of heat distortion resistance, mechanical properties, bleed resistance, and manufacturability of the composition.

(C-1) Softener for non-aromatic rubber:
The component (c-1) is a non-aromatic mineral oil (hydrocarbon compound derived from petroleum or the like) or a synthetic oil (synthetic hydrocarbon compound), usually in the form of liquid, gel or gum at normal temperature is there. The term "non-aromatic" as used herein means that mineral oil is not classified as aromatic in the following categories (the number of aromatic carbons is less than 30%). For synthetic oils, it means that aromatic monomers are not used.

A mineral oil used as a softener for rubber is a combined mixture of any one or more of a paraffin chain, a naphthene ring, and an aromatic ring, and having 30 to 45% of naphthene ring carbon number is a naphthenic oil, Those with 30% or more aromatic carbons are called aromatics, and those that do not belong to naphthenes or aromatics and those with paraffinic chain carbons occupying 50% or more of the total number of carbons are paraffinic It is called and distinguished.

Examples of the component (c-1) include paraffinic mineral oils such as linear saturated hydrocarbons, branched saturated hydrocarbons, and derivatives thereof; naphthenic mineral oils; hydrogenated polyisobutylene, polyisobutylene, and the like Synthetic oils such as polybutene; and the like can be mentioned. Commercially available examples of component (c-1) include isoparaffin hydrocarbon oil "NA Solvent (trade name)" manufactured by NOF Corporation and n-paraffin process oil "PW-90 (trade name)" manufactured by Idemitsu Kosan Co., Ltd. And “PW-380 (trade name)”, synthetic isoparaffin hydrocarbon “IP-Solvent 2835 (trade name)” of Idemitsu Petrochemical Co., Ltd., and n-paraffin process oil “Neothiozole” (product of Sanko Chemical Industry Co., Ltd.) Name) and the like. Among these, paraffinic mineral oils are preferable, and paraffinic mineral oils having a small number of aromatic carbons are more preferable, from the viewpoint of compatibility. From the viewpoint of handleability, those which are liquid at room temperature are preferred. As component (c-1), a mixture of one or more of these can be used.

From the viewpoint of heat resistance and handleability, the component (c-1) preferably has a dynamic viscosity at 37.8 ° C. of 20 to 1000 cSt. Moreover, from a viewpoint of handleability, a pour point is preferably -10--15 ° C. Furthermore, from the viewpoint of safety, the flash point (COC) is preferably 170 ° C. or more.

(C-2) Polar plasticizer:
The component (c-2) is a synthetic compound having a polar group in the molecule and being liquid at normal temperature. Component (c-1) is distinguished from the component (c-1) in that it has a polar group and is not a hydrocarbon compound.

Examples of the component (c-2) include di-2-ethylhexyl phthalate, dibutyl phthalate, butyl hexyl phthalate, diheptyl phthalate, dioctyl phthalate, diisononyl phthalate, diisodecyl phthalate, dilauryl phthalate, and dicyclohexyl. Phthalates and phthalate plasticizers such as dioctyl terephthalate; dioctyl adipate, diisononyl adipate, diisodecyl adipate, and adipate plasticizers such as di (butyl diglycol) adipate; triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, Tri (isopropyl phenyl) phosphate, triethyl phosphate, tributyl phosphate, trioctyl phosphate, tri (butoxyethyl) phosphate Phosphate plasticizer systems such as octyl diphenyl phosphate; as polyhydric alcohols ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,3-butanediol, 1,4 -As a dibasic acid using butanediol, 1,5-hexanediol, 1,6-hexanediol, neopentyl glycol etc., oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid , Polyester based plasticizers using, as necessary, monohydric alcohol or monocarboxylic acid as a stopper, using suberic acid, azelaic acid, sebacic acid, phthalic acid, terephthalic acid, etc .; diisononyl cyclohexane dicarboxylate, dimethyl Cyclohexane dicarboxylate plasticizers such as chlorohexane dicarboxylate, diethyl cyclohexane dicarboxylate, and di-2-ethylhexyl cyclohexane dicarboxylate; Other, tetrahydrophthalic acid plasticizer, azelaic acid plasticizer, sebacic acid system Examples thereof include plasticizers, stearic acid plasticizers, citric acid plasticizers, trimellitic acid plasticizers, pyromellitic acid plasticizers, biphenyltetracarboxylic acid ester plasticizers, and chlorine plasticizers. Among these, di-2-ethylhexyl phthalate and diisononyl phthalate are preferable from the viewpoint of heat and oil resistance. As a component (c-2), 1 type (s) or 2 or more types of mixtures of these can be used.

(D) Block copolymer of aromatic vinyl compound and conjugated diene compound, etc .:
The component (d) is one selected from the group consisting of a block copolymer of an aromatic vinyl compound and a conjugated diene compound, and a hydrogenated product of a block copolymer of an aromatic vinyl compound and a conjugated diene compound It is above. Component (d) is distinguished from component (a) above in that unsaturated nitriles are not used as monomers. Component (d) works to improve heat and oil resistance and mechanical properties.

The aromatic vinyl compound is a polymerizable monomer having a polymerizable carbon-carbon double bond and an aromatic ring. Examples of the aromatic vinyl compound include styrene, t-butylstyrene, α-methylstyrene, p-methylstyrene, divinylbenzene, 1,1-diphenylstyrene, N, N-diethyl-p-aminoethylstyrene, vinyl toluene And p-tert-butyl styrene and the like. Of these, styrene is preferred. As an aromatic vinyl compound, these 1 type (s) or 2 or more types can be combined and used.

The conjugated diene is a compound described above in the description of the component (a), and can be mentioned the above. Among these, 1,3-butadiene and isoprene are preferred. As conjugated dienes, one or more of these may be used in combination.

The block copolymer of the aromatic vinyl compound and the conjugated diene compound is preferably, from the viewpoint of heat resistance and mechanical properties, two or more polymer blocks A mainly composed of the aromatic vinyl compound, and the conjugated diene compound Block copolymer consisting mainly of one or more polymer blocks B. For example, block copolymers having structures such as A-B-A, B-A-B-A, and A-B-A-B-A can be mentioned.

The content of the structural unit derived from the aromatic vinyl compound of the block copolymer of the above aromatic vinyl compound and the conjugated diene compound is preferably 5 to 60% by mass, more preferably from the viewpoint of heat resistance and mechanical properties. It is 20 to 50% by mass.

The polymer block A is a polymer block consisting only of an aromatic vinyl compound or a copolymer block of an aromatic vinyl compound and a conjugated diene compound. When the polymer block A is a copolymer block, the content of the structural unit derived from the aromatic vinyl compound in the polymer block A is usually 50% by mass or more, preferably from the viewpoint of heat resistance oil and mechanical properties. Is 70% by mass or more, more preferably 90% by mass or more. The distribution of structural units derived from the conjugated diene compound in the polymer block A is not particularly limited and is arbitrary. When two or more polymer blocks A are present, they may have the same structure or different structures.

The polymer block B is a polymer block consisting only of a conjugated diene compound or a copolymer block of an aromatic vinyl compound and a conjugated diene compound. When the polymer block B is a copolymer block, the content of structural units derived from the conjugated diene compound in the polymer block B is usually 50% by mass or more, preferably from the viewpoint of flexibility and mechanical properties. It is 70% by mass or more, more preferably 90% by mass or more. The distribution of structural units derived from the aromatic vinyl compound in the polymer block B is not particularly limited and is arbitrary. The manner of bonding of the conjugated diene compound and the conjugated diene compound (hereinafter sometimes abbreviated as microstructure) is not particularly limited and is arbitrary. When there are two or more polymer blocks B, they may have the same structure or different structures.

The number average molecular weight of the block copolymer of the aromatic vinyl compound and the conjugated diene compound is preferably 5,000 to 1,500,000, more preferably 10,000 to 1,500, from the viewpoint of heat resistance and mechanical properties. It is 550,000, more preferably 100,000 to 400,000. The molecular weight distribution (mass average molecular weight / number average molecular weight) is preferably 10 or less from the viewpoint of mechanical properties.

The molecular chain structure of the block copolymer of the aromatic vinyl compound and the conjugated diene compound may be linear, branched, radial or any combination thereof.

Examples of the block copolymer of the aromatic vinyl compound and the conjugated diene compound include styrene-butadiene-styrene block copolymer (SBS), and styrene-isoprene-styrene block copolymer (SIS). Can.

The block copolymer of the aromatic vinyl compound and the conjugated diene compound is not particularly limited, and any aromatic vinyl compound and any conjugated diene can be prepared by the method described in Japanese Patent Publication No. 40-023798, etc. What was obtained by copolymerizing by the well-known method of can be used.

The hydrogenated product of the block copolymer of the aromatic vinyl compound and the conjugated diene compound is obtained by hydrogenating the carbon-carbon double bond in the block copolymer of the aromatic vinyl compound and the conjugated diene compound. -It is obtained by making it a single carbon bond. The hydrogenation can be carried out by a known method, for example, hydrogen treatment using a hydrogenation catalyst in an inert solvent.

Hydrogenation rate of the above-mentioned hydrogen additive (carbon-carbon single bond by hydrogenation relative to the number of carbon-carbon double bonds in the block copolymer of the aromatic vinyl compound and the conjugated diene compound before the hydrogenation) Is not particularly limited, but may be usually 50% or more, preferably 70% or more, more preferably 90% or more from the viewpoint of bleed resistance.

When the conjugated diene polymer block of the above-mentioned hydrogenated substance is a butadiene polymer block, its microstructure is preferably 20 to 50% by mass, more preferably 25 from the viewpoint of flexibility of 1,2-bond. It may be ̃45 mass%. Further, from the viewpoint of heat aging resistance and weather resistance, the 1,2-bond may be selectively hydrogenated.

When the conjugated diene polymer block of the above-mentioned hydrogen additive is a copolymer block of isoprene and butadiene, its microstructure is preferably 50 mass% from the viewpoint of heat aging resistance and weather resistance of 1,2-bond. It may be less than%, more preferably less than 25%, even more preferably less than 15%.

When the conjugated diene polymer block of the above-mentioned hydrogenated substance is an isoprene polymer block, its microstructure may be preferably 70 to 100% by mass from the viewpoint of flexibility of the 1,4-bond. The hydrogenation rate is preferably 90% or more from the viewpoint of bleed resistance.

The content of the structural unit derived from the aromatic vinyl compound in the above-mentioned hydrogenated substance is preferably 5 to 70% by mass, more preferably 20 to 50% by mass from the viewpoint of heat resistant oil and mechanical properties. The number average molecular weight of the above-mentioned hydrogen additive is preferably 150,000 or more, more preferably 200,000 or more from the viewpoint of bleed resistance. From the viewpoint of compatibility, it is preferably 500,000 or less, more preferably 400,000 or less.

As the above-mentioned hydrogen additive, styrene-ethylene-butene copolymer (SEB), styrene-ethylene-propylene copolymer (SEP), styrene-ethylene-butene-styrene copolymer (SEBS), styrene-ethylene-propylene copolymer -Styrene copolymer (SEPS), and styrene-ethylene-ethylene-propylene-styrene copolymer (SEEPS) etc. can be mentioned. Among these, styrene-ethylene-butene-styrene copolymer (SEBS), styrene-ethylene-propylene-styrene copolymer (SEPS), and from the viewpoint of flexibility, heat-resistant oil-resistance and heat-resistant compression set characteristics. Styrene-ethylene-ethylene-propylene-styrene copolymers (SEEPS) are preferred.

As said component (d), these 1 type, or 2 or more types of mixtures can be used.

The compounding amount of the component (d) is preferably at least 5 parts by mass, preferably 100 parts by mass of the component (a), from the viewpoint of flexibility, heat-resistant compression set characteristics, mechanical properties, and manufacturability of the composition. Is 15 parts by mass or more. From the viewpoint of heat resistant oil and compatibility, it is 80 parts by mass or less, preferably 70 parts by mass or less. The blending amount of the component (d) is more preferably 15 to 70 parts by mass. When the content of the component (d) is in the above range, a thermoplastic elastomer composition can be obtained in which the balance between the flexibility and the heat-resistant oil and heat-resistant compression set characteristics is extremely excellent.

(E) Organic peroxides:
The component (e) is a compound in which one or two hydrogen atoms of hydrogen peroxide are substituted with an organic radical. The component (e) has a peroxide bond in its molecule, so it generates radicals during melt-kneading, and causes the radicals to react in a chain to crosslink the component (a) and the component (d). do. At the same time, the component (b) is decomposed to control the flowability of the composition at the time of melt-kneading to make the dispersion of the rubber component better.

As the above component (e), for example, dicumyl peroxide, di-tert-butyl peroxide, 2,5-dimethyl-2,5-di- (tert-butylperoxy) hexane, 2,5-dimethyl- 2,5-di- (tert-butylperoxy) hexyne-3, 1,3-bis (tert-butylperoxyisopropyl) benzene, 1,1-bis (tert-butylperoxy) -3,3,5 -Trimethylcyclohexane, n-butyl-4,4-bis (tert-butylperoxy) valerate, benzoyl peroxide, p-chlorobenzoyl peroxide, 2,4-dichlorobenzoyl peroxide, tert-butyl peroxybenzoate, tert -Butylperoxyisopropyl carbonate, diacetyl peroxide, lauroyl Peroxides, and the like tert- butyl cumyl peroxide and the like. Among them, 2,5-dimethyl-2,5-di- (tert-butylperoxy) hexane, and 2,5-dimethyl-2,5 in view of odor, color and scorch safety. -Di- (tert-butylperoxy) hexyne-3 is preferred. As the component (e), a mixture of one or more of them can be used.

The compounding amount of the component (e) is 0.5 parts by mass or more, preferably 0. 8 parts by mass or more. It is 2.5 parts by mass or less from the viewpoint of mechanical properties, compatibility, and injection moldability. The compounding amount of the component (e) is more preferably 0.8 to 2.5 parts by mass. When the content of the component (e) is in the above range, a thermoplastic elastomer composition can be obtained in which the balance between the flexibility and the heat-resistant oil and heat-resistant compression set characteristics is extremely excellent.

In the thermoplastic elastomer composition of the present invention, if necessary, a heat stabilizer, an antioxidant, a light stabilizer, an ultraviolet light absorber, a crystal nucleating agent, an antiblocking agent, a sealability, as long as the object of the present invention is not violated. Modifiers, mold release agents (for example, stearic acid and silicone oil etc.), lubricants such as polyethylene wax, colorants, pigments, inorganic fillers (for example, alumina, talc, calcium carbonate, mica, wollastonite, and clay Etc.), blowing agents (organic, inorganic), and flame retardants (eg, hydrated metal compounds, red phosphorus, ammonium polyphosphate, antimony compounds, silicon etc.) and the like can be included.

Examples of the above antioxidant include 2,6-di-tert-p-butyl-p-cresol, 2,6-di-tert-butylphenol, 2,4-dimethyl-6-tert-butylphenol, and 4,4. -Phenolic antioxidants such as dihydroxydiphenyl and tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, phosphite antioxidants, thioether antioxidants and the like can be mentioned. Among these, phenolic antioxidants and phosphite antioxidants are preferred. As the antioxidant, a mixture of one or more of these can be used.

Method of producing a thermoplastic elastomer composition:
The thermoplastic elastomer composition of the present invention is melted using an optional melt kneader, adding the above components (a) to (e) and optional components used as desired simultaneously or in any order. It can be obtained by kneading.

From the viewpoint of ensuring that the component (e) works, the melt-kneading is preferably performed for 1 minute or more at a temperature of 1 minute half-life temperature of the component (e) or more. It is more preferable to carry out for 2 minutes or more at the temperature more than 1 minute half life temperature of a component (e). The melt-kneading temperature may be usually 240 ° C. or less, preferably 220 ° C. or less, from the viewpoint of mechanical properties, the productivity of the composition, and the injection moldability.

Examples of the melt kneader include batch kneaders such as a pressure kneader and a mixer; extrusion kneaders such as a single screw extruder, a corotating twin screw extruder, and a corotating twin screw extruder; a calender roll kneader; You can raise You may use combining these arbitrarily. The resulting composition can be formed into any article by any method after being pelletized by any method. The pelletization can be carried out by methods such as hot cut, strand cut, and underwater cut.

Hereinafter, the present invention will be described by way of examples, but the present invention is not limited thereto.

Measurement method (1) Hardness:
According to JIS K 6253-3: 2012, a 15-second value of durometer hardness (type A) was measured using a 6.3 mm thick press sheet as a test piece. The hardness may be preferably 45 or more, more preferably 55 or more from the viewpoint of mechanical strength. From the viewpoint of the performance as an elastic body, it may be preferably 90 or less, more preferably 80 or less.

(2) Volume swelling ratio (oil resistance at high temperature):
According to JIS K 6258: 2003, a specimen punched out of a 2 mm-thick press sheet was used to measure the volume swelling after immersion in IRM # 903 oil at a temperature of 120 ° C. for 72 hours. The volume swelling ratio is preferably 0 to 40%, more preferably 0 to 35%.

(3) Compression set (compression set at high temperature):
According to JIS K 6262: 2013, using a small test piece punched from a 6.3 mm-thick press sheet, measurement was made under conditions of 25% compression deformation, temperature 120 ° C., 22 hours, and method A. The compression set is preferably 70% or less, more preferably 60% or less.

(4) Mechanical properties (tensile strength and tensile elongation):
In accordance with JIS K 6251: 2010, using a No. 3 dumbbell punched out of a 1 mm thick press sheet as a test piece, measurement was performed under a condition of a tensile speed of 500 mm / min. The tensile strength may be preferably 3.0 MPa or more, more preferably 5.0 MPa or more. The tensile elongation may be preferably 150% or more, more preferably 200% or more.

(5) Injection moldability and compatibility:
A 130 mm × 130 mm × 2 mm sheet (gate shape: film gate, gate dimension: 130 × 0.5 mm) is injected using a 120 ton clamping pressure injection molding machine, molding temperature 220 ° C., mold temperature 30 ° C. speed 55 mm / sec, injection pressure 1400 kg / cm ^2, holding pressure 400 Kg / cm ^2, an injection time of 5 seconds, and the condition of the cooling time 20 seconds, injection molded. The obtained sheet was visually observed and evaluated according to the following criteria.
(5-1) Injection molding property:
○: No occurrence of flow marks and sink marks.
X: At least one of flow mark and sink has occurred.
(5-2) Compatibility:
○: The sheet surface is smooth.
X: Bodicz powder like powder is observed on the sheet surface.

(6) Bleeding resistance:
The surface of the test piece after the test of the above test (3) was visually observed and evaluated according to the following criteria.
○: No occurrence of bleeding on the surface of the test piece.
X: Bleeding has occurred on the surface of the test piece.

(7) Manufacturability of the composition:
Using an apparatus equipped with a twin-screw extruder and a strand-cut type granulator, the productivity when melt-kneaded under the conditions of an extruder outlet temperature of 180 ° C. was evaluated based on the following criteria.
○: The strand was stably closed.
X: The strand is not stable.

Ingredients used Ingredient (a):
(A-1) Acrylonitrile-butadiene copolymer rubber “(PNC-48 (trade name)” of JSR Corporation, nitrile content 30 mass%, Mooney viscosity (ML (1 + 4) 100 ° C.) 60.
(A-2) Acrylonitrile-butadiene copolymer rubber “PN-30A (trade name)” manufactured by JSR Corporation, nitrile content 35 mass%, Mooney viscosity (ML (1 + 4) 100 ° C.) 56.

Comparison component (a '):
(A′-1) Chlorinated butyl rubber “CHLOROBUTYL 1066 (trade name)” manufactured by JSR Corporation, specific gravity 0.92, Mooney viscosity (ML (1 + 8) 125 ° C.) 38, chlorine content 1.2 mass%.

Component (b):
(B-1) Propylene-ethylene block copolymer “Novatec PP BC08AHA (trade name)” of Japan Polypropylene Corporation, melt mass flow rate (230 ° C., 21.18 N) 80 g / 10 min, peak top melting point 165 ° C.

Component (c-1):
(C-1-1) Paraffin oil “Diana Process Oil PW-90 (trade name)” manufactured by Idemitsu Kosan Co., Ltd., 71% by mass of paraffin component, and 29% by mass of naphthene component.
(C-1-2) Naphthenic oil "Diana Process Oil NS-100 (trade name)" manufactured by Idemitsu Kosan Co., Ltd., 34 mass% of a naphthenic component.

Component (c-2):
(C-2-1) Phthalate ester plasticizer (di (2-ethylhexyl) phthalate) "JOP LASER""DOP (trade name)".
(C-2-2) Trimellitic acid ester plasticizer of Kao Corporation (2-ethylhexyl trimellitic acid) "TOTM (trade name)".
(C-2-3) Adipate-based plasticizer (di (2-ethylhexyl) adipate) “DOA (trade name)” of J-PLUS Co., Ltd.
(C-2-4) A cyclohexanedicarboxylate plasticizer (Diisononylcyclohexane-1,2-dicarboxylate) manufactured by BASF Japan Ltd. "Hexamoll DINCH (trade name)".

Component (d):
(D-1) Styrene-ethylene-ethylene-propylene-styrene copolymer "SEPTON 4077 (trade name)" manufactured by Kuraray Co., Ltd., styrene content 30% by mass, number average molecular weight 260,000, mass average molecular weight 320,000, molecular weight Distribution 1.23, hydrogenation rate 90% or more.
(D-2): Styrene-ethylene-butene-styrene copolymer "Clayton G 1651H (trade name)" manufactured by Kraton Polymers, styrene content 30 mass%, number average molecular weight 290,000, mass average molecular weight 260,000, molecular weight Distribution 1.12, 90% or more of hydrogenation rate.

Ingredient (e):
(E-1) 2,5-Dimethyl-2,5-di (t-butylperoxy) hexane "Perhexa 25B (trade name)" manufactured by NOF Corp., one-minute half-life temperature 179 ° C.

Examples 1-22, Comparative Examples 1-11
The components of the amount (parts by mass) shown in any one of Tables 1 to 5 are melted at an extruder outlet temperature of 180 ° C. using an apparatus equipped with a twin-screw extruder and a strand-cut granulator. It knead | mixed and obtained the pellet of the composition. The above tests (1) to (7) were performed. The results are shown in any one of Tables 1 to 5.

The thermoplastic elastomer composition of the present invention is very flexible and is very excellent in oil resistance and compression set properties at high temperatures. It is also excellent in tensile strength, tensile elongation, compatibility, bleed resistance, manufacturability of the composition, and injection moldability.

On the other hand, the comparative example is at least one of flexibility, oil resistance at high temperature, compression set at high temperature, tensile strength, tensile elongation, compatibility, bleed resistance, manufacturability of the composition, and injection moldability. 1 is insufficient.

Claims (6)

(A) 100 parts by mass of copolymer rubber of unsaturated nitrile and conjugated diene;
(B) polypropylene resin 10 to 150 parts by mass;
(C) Softener 20 to 160 parts by mass;
(D) At least one selected from the group consisting of block copolymers of aromatic vinyl compounds and conjugated diene compounds, and hydrogenated products of block copolymers of aromatic vinyl compounds and conjugated diene compounds Parts by mass; and
(E) organic peroxide 0.5 to 2.5 parts by mass;
And (c) the softener comprises
(C-1) Softener for non-aromatic rubber (non-aromatic mineral oil or synthetic hydrocarbon compound) 40 to 80% by mass; and (c-2) polar plasticizer (excluding hydrocarbon compound) .) 60 to 20 wt%;
A thermoplastic elastomer composition comprising: the above component (c-1) and the above component (c-2), wherein the sum is 100% by mass.
The (c-2) polar plasticizer is a phthalate ester plasticizer, a phosphate ester plasticizer, an adipate plasticizer, a trimellitic ester plasticizer, a polyester plasticizer, an epoxy plasticizer, Sebacic acid ester plasticizer, azelaic acid ester plasticizer, citric acid ester plasticizer, glycolic acid plasticizer, ricinoleic acid plasticizer, maleic acid ester plasticizer, fumaric acid ester plasticizer, pyromellitic acid The thermoplastic elastomer composition according to claim 1, which is at least one selected from the group consisting of an ester plasticizer, an itaconic acid plasticizer, and a cyclohexane dicarboxylate plasticizer.
The thermoplastic elastomer composition according to claim 1 or 2, wherein the (c-1) non-aromatic softening agent for rubber is at least one selected from the group consisting of paraffin oil and naphthenic oil. object.
The method for producing a thermoplastic elastomer composition according to any one of claims 1 to 3, wherein the melt-kneading is carried out at a temperature equal to or higher than the one-minute half-life temperature of the (e) organic peroxide.
An article comprising the thermoplastic elastomer composition according to any one of claims 1 to 3.
A method of manufacturing an article,
Producing a thermoplastic elastomer composition by the method according to claim 4;
Producing an article using the thermoplastic elastomer composition obtained in the above step;
Method including.