JP4173500B2 - Method for producing thermoplastic elastomer composition - Google Patents

Description

  The present invention relates to a thermoplastic elastomer composition, and in particular, relates to a thermoplastic elastomer composition that is excellent in flexibility, rubber elasticity, weather resistance, mechanical strength and molding processability, and has few softening agent bleeds. Food use, daily goods use, toy / exercise equipment use, stationery use such as desk mat, automotive interior / exterior use, civil engineering / architecture use such as civil engineering sheet, waterproof sheet, AV / home appliance use, OA / office equipment use, Apparel and footwear use, textile use, medical use such as gaskets and caps for catheters and medical equipment, sanitary goods such as paper diapers and sanitary products, chemical and mining industry materials, packaging and transport materials, agricultural, livestock and fishery materials, etc. It can be widely used in the field.

  In recent years, thermoplastic elastomer that is a soft material having rubber elasticity and does not require a vulcanization process, and can be molded and recycled in the same manner as a thermoplastic resin, automotive parts, home appliance parts, electric wire coatings, medical parts, Widely used in the fields of miscellaneous goods and footwear. Among such thermoplastic elastomers, a hydrogenated vinyl aromatic hydrocarbon-conjugated diene compound block copolymer (hereinafter referred to as a hydrogenated block copolymer) is referred to as a hydrogenated block copolymer. Some proposals have been made regarding elastomeric compositions using “abbreviated”). For example, Japanese Patent Application Nos. 50-14742, 52-65551, and 58-206644 disclose elastomers in which a hydrocarbon oil and an olefin polymer are blended with a hydrogenated block copolymer. Further, JP-A-59-131613 discloses an elastomeric composition in which a hydrogenated block copolymer is blended with a hydrocarbon oil, an olefin polymer, and an inorganic filler. Proposals have been made to improve the rubber elasticity (compression set) at high temperatures of the obtained elastomeric composition by partially crosslinking using an oxide and a crosslinking aid.

  The hydrogenated block copolymer elastomeric composition described in JP-A-59-131613 is excellent in rubber elasticity at 70 ° C. (compression set) but inferior in rubber elasticity at 100 ° C. or higher. Although it does not reach the level of compression set at high temperature achieved with vulcanized rubber and has the recyclability characteristic of thermoplastic elastomers, rubber elasticity at high temperature is It is still insufficient.

In order to improve the compression set, a polymer having a high molecular weight is generally used. However, even if a high molecular weight polymer is simply used, the melt viscosity becomes high, which causes problems such as delamination near the gate during injection molding and product deformation due to residual molding distortion.
That is, the object of the present invention is to reduce the elasticity of a thermoplastic elastomer at a high temperature (compression permanent) without impairing the physical properties such as excellent flexibility, rubber elasticity, weather resistance, mechanical strength, etc. An object of the present invention is to provide a thermoplastic elastomer composition containing a hydrogenated block copolymer, which can give a molded article having a good (strain), excellent molding processability and little molding distortion.

  The present inventor has made various compositions to solve the above problems, and as a result, uses a hydrogenated block copolymer composed of a specific monovinyl aromatic hydrocarbon block-conjugated diene block to form a composition. Therefore, the flexibility, weather resistance and mechanical strength are excellent, and the rubber elasticity at high temperature is dramatically improved. Furthermore, by dynamically applying heat treatment in the presence of a crosslinking agent, the molding processability is improved. As a result, the inventors have found that delamination and the like during injection molding do not occur and molding distortion is reduced, and the present invention has been completed.

That is, the gist of the present invention is as follows.
[1] It contains the following three components (A), (B), and (C), and the ratio of (A) / (B) is 20/80 to 80/20 (weight ratio): A thermoplastic elastomer composition obtained by dynamically heat-treating a mixture containing 1 to 300 parts by weight of (c) in the presence of a crosslinking agent when the total amount of (b) and (b) is 100 parts by weight.
(B) A hydrogenated block copolymer having a weight average molecular weight (hereinafter referred to as “Mw”) of 200,000 to 450,000, wherein the molecular weight in the hydrogenated product of the block copolymer is more than 400,000 A hydrogenated block copolymer represented by the following general formula (1) or (2), wherein the proportion of the polymer is 5% by weight or more and the proportion of the polymer having a molecular weight of 200,000 or less is 20% by weight or less; Exist.

In the formula, A is a polymer block composed of monovinyl aromatic hydrocarbon units, B is a polymer block composed of conjugated diene units, and n represents an integer of 1 to 5.
(B) Rubber softener (c) Olefin polymer.

  [2] The thermoplastic elastomer composition according to [1], wherein the block copolymer of component (a) is a styrene-butadiene block copolymer or a styrene-isoprene block copolymer. [3] The thermoplastic elastomer composition according to [1] or [2], wherein the rubber softener for component (b) is a mineral oil rubber softener, and the olefin polymer for component (4) (c) Is at least one olefin polymer selected from the group consisting of propylene polymers, especially propylene homopolymers, ethylene / propylene random copolymers, and ethylene-propylene block copolymers. The thermoplastic elastomer composition according to any one of [3] and [5] 0.1 to 3% by weight of the cross-linking agent are used with respect to the total amount of the three components (A) to (C). Other aspects of the in the thermoplastic elastomer of the serial sections has exist and the invention is in exist in [6] above thermoplastic elastomer composition formed by molding a medical device molded article.

The thermoplastic elastomer composition of the present invention is excellent in flexibility, rubber elasticity and molding processability, has no softening agent bleed, and remarkably excellent in rubber elasticity at high temperatures. Furthermore, by dynamically applying heat treatment in the presence of a cross-linking agent, molding processability is improved, defects such as delamination during injection molding are less likely to occur, and molding distortion is reduced, so deformation of the molded product at high temperatures. Also does not happen.
Since the thermoplastic elastomer composition of the present invention has the above-mentioned excellent characteristics, it is used for food, daily goods, toys and exercise equipment, stationery such as desk mats, automotive interior and exterior applications, Civil engineering / architecture applications such as civil engineering sheets and waterproof sheets, AV / home appliance applications, OA / office equipment applications, clothing / footwear applications, textile applications, catheters, medical devices such as gaskets and caps, paper diapers / physiology It can be widely used in fields such as sanitary goods such as goods, chemical / mining industrial materials, packaging transportation materials, agricultural / livestock / fishery materials.
In particular, a molded article based on the composition of the present invention is suitable for use in a medical device that is subjected to heat sterilization because the above-described effects are remarkably exhibited.

  In the composition of the present invention, the weight average molecular weight (Mw) of the hydrogenated product of the component (a) block copolymer is 200,000 to 450,000. A more preferable range of Mw is in the range of 250,000 to 400,000. When the weight average molecular weight is less than 200,000, the rubber elasticity and mechanical strength of the resulting thermoplastic elastomer are inferior. On the other hand, when it exceeds 450,000, the viscosity at the time of melting becomes high and the molding processability is inferior.

  In the present invention, the proportion of the polymer having a molecular weight of 400,000 or more in the hydrogenated product of the block copolymer is 5% by weight or more. The preferred content of the polymer having a molecular weight of 400,000 or more is 8% by weight or more, more preferably 10% by weight or more. The proportion of the polymer having a molecular weight of 200,000 or less is 20% by weight or less, preferably 15% by weight or less. When the polymer having a molecular weight of 400,000 or more is less than 5% by weight or the polymer having a molecular weight of 200,000 or less exceeds 20% by weight, only a composition having inferior rubber elasticity at a high temperature of 100 ° C. or more can be obtained.

  In addition, the weight average molecular weight (Mw) as used in the field of this invention means the weight average molecular weight of polystyrene conversion measured by the gel permeation chromatography (GPC) on the following conditions.

(Measurement condition)
GPC: HLC-8020 (manufactured by Tosoh)
Detector: differential refractometer RI-8010 (manufactured by Tosoh Corporation)
Data processor: TriSEC (GPC Module Ver. 3.0-ac) (manufactured by Viscotek)
Column: 3 TSKgel GMHHR (Tosoh products)
Solvent: Tetrahydrofuran (special grade reagent manufactured by Kanto Chemical)
Temperature: 40 ° C
Flow rate: 1 ml / min
Injection volume: 0.1ml
Concentration: 2 mg / ml

Sample preparation: Tetrahydrofuran added with 0.2% by weight of 2,6-di-t-butyl-p-phenol (BHT) was used as a solvent and dissolved by stirring for 5 hours at room temperature. Calibration curve: Standard polystyrene (A-2500, GPC measurement of A-5000, F-2, F-4, F-10, F-20, F-40, F-80, F-380, F-850 (manufactured by Tosoh)) is performed, and the cubic equation Create a calibration curve with. Also, the flow rate is corrected using the BHT elution time.

  As the monovinyl aromatic hydrocarbon unit of the monomer constituting the polymer block (A) of the block copolymer of the component (a) of the composition of the present invention, styrene, α-methylstyrene and the like are preferably used. Particularly preferred is styrene. The conjugated diene unit in the polymer block (B) is preferably butadiene or isoprene, or a mixture of both. When butadiene alone forms the polymer block (B), the 1,2-addition structure in the microstructure of the polymer block (B) (polybutadiene) is 20 to 50% of the whole. In order to maintain elastomeric properties after hydrogenation, a 1,2-addition structure of 35 to 45% is particularly preferable.

The molecular structure of the block copolymer may be linear, branched, radial, or a combination thereof.
The proportion of the polymer block (A) in the copolymer is 10 to 50% by weight, preferably 15 to 45% by weight, and more preferably 20 to 40% by weight. When the polymer block (A) is less than 10% by weight, the resulting thermoplastic elastomer tends to be inferior in mechanical strength and rubber elasticity. On the other hand, when the polymer block (A) exceeds 40% by weight, flexibility and rubber elasticity tend to be inferior and the softening agent tends to bleed, which is also not preferable.

The block copolymer used in the present invention may be produced by any production method as long as the above physical properties can be obtained. For example, it can be obtained by block copolymerization in an inert solvent using a lithium catalyst or the like by the method described in Japanese Patent Publication No. 40-23798.
Further, the hydrogenation treatment of such a block copolymer is described in, for example, JP-B-42-8704, JP-B-43-6636, JP-A-59-133203, and JP-A-60-79005. Can be carried out in an inert solvent in the presence of a hydrogenation catalyst. In this hydrogenation treatment, at least 50%, preferably 80% or more of the olefinic double bonds in the polymer block (B) are hydrogenated, and the aromatic unsaturated bonds in the polymer block (A). It is preferable that only 25% or less be hydrogenated.

Commercial products of such hydrogenated block copolymers include “KRATON-G” (Shell Chemical), “Septon” (Kuraray Co., Ltd.), “Tuftec” (Asahi Kasei Co., Ltd.), and the like.
The rubber softener used as the component (b) in the present invention is not particularly limited, but a mineral oil type or synthetic resin type is preferable.

  Mineral oil softeners are generally a mixture of aromatic hydrocarbons, naphthenic hydrocarbons and paraffinic hydrocarbons, where the number of carbon atoms in the paraffinic hydrocarbons accounts for 50% or more of the total carbon atoms. It is called paraffinic oil, while naphthenic hydrocarbons with 30-45% carbon atoms are called naphthenic oils, and aromatic hydrocarbons with 35% or more carbon atoms are called aromatic oils. It is divided. Of these, paraffinic oil is particularly preferable as the rubber softener used in the present invention.

The paraffinic oil has a kinematic viscosity at 40 ° C. of 20 to 800 cst (centistokes), preferably 50 to 600 cst, a fluidity of 0 to −40 ° C., preferably 0 to −30 ° C., and a flash point (COC method). ) Is 200 to 400 ° C, preferably 250 to 350 ° C.
As the synthetic resin softener, polybutene, low molecular weight polybutadiene, or the like can be used.

The rubber softener used in the composition of the present invention is preferably a mineral oil softener.
Examples of the olefin polymer used as the component (c) in the present invention include ethylene polymers, propylene polymers, polybutene-1, poly-4-methylpentene-1, and the like. Among these, ethylene-based polymers are preferred. A polymer and a propylene-based polymer. Of these, propylene-based copolymers are particularly preferred.

  Examples of the ethylene polymer include ethylene homopolymers such as high density polyethylene, medium density polyethylene and low density polyethylene, ethylene / butene-1 copolymer, ethylene / hexene copolymer, and ethylene / heptene copolymer. Copolymer, ethylene / octene copolymer, ethylene / 4-methylpentene-1 copolymer, ethylene / vinyl acetate copolymer, ethylene / acrylic acid copolymer, ethylene / acrylic acid ester copolymer, ethylene / methacrylic acid Examples thereof include copolymers and ethylene / methacrylic acid ester copolymers, among which high density polyethylene, medium density polyethylene and low density polyethylene are preferred.

  The propylene-based polymers include propylene homopolymers, ethylene / propylene / random copolymers, ethylene / propylene block copolymers, propylene / butene-1 copolymers, propylene / ethylene / butene-1 copolymers. , Propylene / 4-methylpentene-1 copolymer, and the like. Among these, propylene homopolymer, ethylene / propylene random copolymer, and ethylene-propylene block copolymer are preferable.

  The mixing ratio of the component (A) and the component (B) in the composition of the present invention is 20/80 to 80/20 (weight ratio) as the ratio (A) / (B). A more preferable ratio is (A) / (B) = 25/75 to 70/30, and more preferably (A) / (B) = 30/70 to 60/40. When the ratio of (a) / (b) is less than 20/80, the resulting elastomer has poor rubber elasticity, and the softening agent tends to bleed. When the ratio of (i) / (b) exceeds 80/20, flexibility and moldability are inferior.

  Component (C) is blended in an amount of 1 to 300 parts by weight, preferably 3 to 200 parts by weight, more preferably 5 to 100 parts by weight, when the total amount of component (a) and (b) is 100 parts by weight. It is. When the blending amount of the component (c) is less than 1 part by weight, the molding processability of the resulting thermoplastic elastomer is inferior. On the other hand, when it exceeds 300 parts by weight, the flexibility of the thermoplastic elastomer is lost and the softening agent tends to bleed. Become.

In the thermoplastic elastomer composition of the present invention, in addition to the above essential components, other compounding components can be blended depending on the purpose within a range that does not significantly impair the effects of the present invention.
What is used as such a component is, for example, an antioxidant, a heat stabilizer, a light stabilizer, an ultraviolet absorber, a neutralizer, a lubricant, an antifogging agent, an antiblocking agent, a slip agent, a dispersant, a coloring agent. Agents, flame retardants, antistatic agents, conductivity-imparting agents, cross-linking agents, cross-linking aids, metal deactivators, molecular weight regulators, antibacterial agents, fluorescent whitening agents, and other additives, other than the essential components Thermoplastic resins, elastomers other than the essential components, fillers, and the like can be given, and one or more of these can be used.

  Examples of thermoplastic resins that can be used include ethylene copolymer resins such as ethylene / vinyl acetate copolymers, ethylene / (meth) acrylic acid copolymers, and ethylene / (meth) acrylic acid ester copolymers, Polyphenylene ether resins, polyamide resins such as nylon 6 and nylon 66, polyester resins such as polyethylene terephthalate and polybutylene terephthalate, acrylic resins such as polymethyl acrylate and polymethyl methacrylate, polyoxymethylene homopolymer, poly Examples include polyoxymethylene resins such as oxymethylene copolymers.

  Examples of elastomers include ethylene / propylene copolymer rubber (EPM), ethylene / propylene / non-conjugated diene copolymer rubber (EPDM), ethylene / butene copolymer rubber (EBM), and ethylene / octene copolymer rubber (EOM). ), Ethylene elastomers such as ethylene / propylene / butene copolymer rubber, styrene elastomers such as styrene / butadiene copolymer rubber and styrene / isoprene copolymer rubber, and polybutadiene.

Examples of the filler include glass fiber, hollow glass sphere, carbon fiber, talc, calcium carbonate, mica, potassium titanate fiber, silica, titanium dioxide, and carbon black.
As a method for obtaining the thermoplastic elastomer composition of the present invention, there are various methods. Among them, the above components (A) to (C) are added as necessary within the above-mentioned blending ratio. Mixing with additives such as those described in the section of the blending component using a Henschel mixer, ribbon blender, V-type blender, etc., and then mixing the mixture with a Banbury mixer, kneader, roll mill, uniaxial or biaxial multi-screw kneading extruder, etc. After kneading and kneading using the above kneading machine, the kneading machine may be further heat-treated dynamically in the presence of a crosslinking agent such as peroxide, or at the same time as the kneading and kneading, You may heat-process. When dynamically heat-treating, a crosslinking aid or an antioxidant may be used in combination.

  It is important that the thermoplastic elastomer composition of the present invention is subjected to a step of dynamically heat-treating in the presence of a crosslinking agent. As a result, molding processability is good, delamination near the gate in injection molding, etc. Thus, it is possible to obtain a thermoplastic elastomer composition that does not cause the above-mentioned problems, has little molding distortion, and does not easily deform the product at a high temperature.

  As the crosslinking agent used in the present invention, an organic peroxide is preferable. As the organic peroxide, either an aromatic peroxide or an aliphatic peroxide can be used, and it may be a single peroxide or a mixture of two or more peroxides. Examples of peroxides that can be used include 2,5-dimethyl-2,5-di (tert-butylperoxy) hexane, 2,5-dimethyl-2,5-di (tert-butylperoxy). ) Hexin-3, tert-butyl peroxybenzoate, dicumyl peroxide, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, tert-butyl-cumyl peroxide, diisopropylbenzene hydroperoxide, benzoyl Those having a 10-hour half-life temperature of 30 to 200 ° C. such as peroxide are preferably used. A more preferable 10-hour half-life temperature is 50 to 180 ° C, more preferably 70 to 170 ° C.

  Moreover, you may use said peroxide together with a crosslinking adjuvant. Examples of such a crosslinking aid include acrylic polyfunctional monomers such as ethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, trimethylolpropane triacrylate, divinylbenzene, liquid polybutadiene, and the like. Further, in the present invention, it is preferable to use an antioxidant together in order to adjust the degree of crosslinking or prevent coloring of the molded product. Such antioxidants include, for example, [1] monophenol compounds, [2] bis, tri- or polyphenol compounds, [3] thiobisphenol compounds, [4] phenols composed of polyphenols or derivatives thereof. And amine compounds comprising [5] naphthylamine compounds, [6] diphenylamine compounds, and [7] p-phenylenediamine compounds.

Examples of the compound belonging to the monophenol compound of [1] above include 2,6-di-tert-butyl-p-cresol, 2,6-di-tert-butylphenol, 2,4-dimethyl-6-tert-butylphenol. 2,4,6-tri-tert-butylphenol and the like.
Examples of the bis, tri or polyphenol compound of [2] above include 4,4-dihydroxydiphenyl, 2,2'-methylenebis (4-ethyl-6-tert-butylphenol), tris (2-methyl-4-hydroxy-). Examples include 5-tert-butylphenyl) butane, tetrakis [methylene-3- (3 ′, 5′-di-tert-butyl-4′-hydroxyphenyl) propionate] methane, and the like.

The above thiobisphenol compounds [3] include 4,4'-thiobis (6-tert-butyl-3-methylphenol) and 2,2'-thiobis (6-tert-butyl-4-methylphenol). ) And the like.
Examples of the polyhydric phenol or derivative thereof [4] include di-tert-butylhydroxy.

Examples of the naphthylamine compound of [5] include phenyl-α-naphthylamine.
Examples of the diphenylamine compound of [6] include p-isoproxydiphenylamine.
Examples of the p-phenylenediamine compound of [7] include N, N′-diphenyl-p-phenylenediamine, N, N′-di-2-naphthyl-p-phenylenediamine, and the like.

Among the compounds [1] to [7], the phenolic antioxidants [1], [2] and [3] are preferably used.
The amount of the crosslinking agent, the crosslinking aid and the antioxidant used is 0.1 to 3 parts by weight, preferably 0.1 to 0.1 parts by weight with respect to 100 parts by weight of the mixture comprising the components (A) to (C). 1 part by weight, 0 to 5 parts by weight of a crosslinking aid, preferably 0.1 to 5 parts by weight, more preferably 0.1 to 3 parts by weight, and 0 to 3 parts by weight, preferably 0. It is good to set it as 05-1 weight part.

In general, the amount of the crosslinking aid is preferably about 1 to 3 times as much as the molar ratio with respect to the crosslinking agent.
When the addition amount of the crosslinking agent is less than 0.1 parts by weight, the effect of improving the molding processability of the obtained elastomeric composition is small, and the occurrence of delamination near the gate at the time of injection molding and deformation at high temperature due to molding distortion. It tends to happen. On the other hand, if the amount added exceeds 3 parts by weight, the cross-linking occurs too quickly, the molding processability deteriorates, and the mechanical strength and elongation decrease.
The temperature of the dynamic heat treatment such as melt kneading is generally in the range of 100 ° C to 400 ° C, preferably in the range of 150 ° C to 300 ° C, particularly preferably in the range of 180 ° C to 280 ° C. The treatment time is 10 seconds to 30 minutes, preferably 20 seconds to 20 minutes.

  The thermoplastic elastomer composition obtained as described above includes, for example, an injection molding method (insert molding method, two-color molding method, sandwich molding method, gas injection molding method, etc.), extrusion molding method, inflation molding method, T It can be molded and processed by molding methods such as die film molding, laminate molding, blow molding, hollow molding, compression molding, and calendar molding.

The molded product molded and processed in this way can be used for industrial parts such as automobile parts and home appliance parts, food packaging materials, medical equipment parts, furniture parts, daily goods, and the like.
Among them, it is preferable to use a molded product formed from the composition of the present invention for medical devices such as a syringe gasket, a dialyzer part, an infusion cap, and the like.
This is because the composition of the present invention has a small compression set at a high temperature, so that the fitting strength and the sealing performance are not impaired even when the composition is heated and sterilized after assembly.

The present invention will be described more specifically with reference to the following examples. However, the present invention is not limited to the following examples unless it exceeds the gist.
<Evaluation method>
All measurement samples were in-line screw type injection molding machine (Toshiba Machine Co., Ltd. small injection molding machine: IS90B) under conditions of injection pressure 500 kg / cm ² , injection temperature 220 ° C., mold temperature 30 ° C. It shape | molded and produced by the horizontal direction punching of a 120mmx80mmx2mm thickness sheet.

(1) Flexibility Based on JIS-K6301, JIS-A hardness was measured.
(2) Rubber elasticity According to JIS-K6301, compression set (22 hours) [%] at 70 ° C, 100 ° C, and 130 ° C was measured.
(3) Bleeding of softening agent After the injection molded sheet was allowed to stand at room temperature for 30 days, the presence or absence of surface stickiness was visually evaluated.

(4) Molding processability In the injection-molded sheet obtained under the molding conditions described above, if there is no short shot and there are no significant appearance defects such as delamination and flow marks in the vicinity of the gate, the moldability is improved. .
(5) Deformation at high temperature (molding strain)
After the injection molded sheet was left in a gear oven at 110 ° C. for 60 minutes, the presence or absence of deformation of the sheet was confirmed.

<Composition ingredients>
Each compounding component used in Examples and Comparative Examples is as follows.
(I) Component (I-1 to I-3)
Block structure of hydrogenated product of monovinyl aromatic hydrocarbon-conjugated diene block copolymer, monomer constituting polymer blocks (A) and (B), content of polymer block (A), weight average molecular weight The polymer content with a molecular weight of 400,000 or more and the polymer content with a molecular weight of 200,000 or less are as shown in Table 1.

(B) Component (b-1) Softener for mineral oil rubber: Paraffin oil
"PW380" made by Idemitsu Kosan Co., Ltd.
40 ° C kinematic viscosity: 381.6 cst
Fluidity: -15 ° C
Flash point: 300 ° C
(C) Component (c-1) Olefin resin: Polypropylene
Mitsubishi Polypro “MA2P” (Mitsubishi Chemical Corporation)
MFR: 22 g / 10 min (230 ° C., 2.16 kg)
(C-2) Olefin resin: Propylene / ethylene copolymer
Mitsubishi Polypro "BC1" (Mitsubishi Chemical Corporation)
MFR: 33 g / 10 min (230 ° C., 2.16 kg)

<Examples 1-4 and Comparative Examples 1-5>
2,5-dimethyl-2,5-di (t-butylperoxy) hexane (10) as a crosslinking agent with respect to 100 parts by weight of the total amount of the composition blended in the blending amount (parts by weight) shown in Table 2. 0.3 part by weight of time half-life temperature: 118 ° C., 0.45 part by weight of divinylbenzene as a crosslinking aid, and 0.05 part by weight of a phenolic antioxidant (trade name “Irganox 1010”), Using a twin screw extruder with L / D = 33 and a cylinder diameter of 45 mm, melt kneading was performed at a temperature of 200 ° C., and at the same time, heat treatment was performed dynamically to obtain a thermoplastic elastomer composition.
Using this composition, injection molding was performed as described above to obtain a sheet, and the obtained sheet was subjected to the above evaluation. These evaluation results are shown in Table 2.
<Comparative Examples 6 and 7>
A composition was prepared according to the formulation shown in Table 2 and evaluated in the same manner as in the above example except that the crosslinking agent and the crosslinking aid were not added. The results are also shown in Table 2.

<Evaluation of results>
From the results of Examples 1 to 4 shown in Table 2, the thermoplastic elastomer composition of the present invention has an excellent balance of flexibility, rubber elasticity and molding processability as compared with Comparative Examples 1 to 4, and is a softener bleed. Furthermore, although the compression set at 70 ° C. is the same, the compression set at 100 ° C. or higher is 41 to 49% (100 ° C.) compared with 51 to 61% of the comparative example, or of the comparative example. It turns out that it is remarkably excellent with 52-58% (130 degreeC) with respect to 63-75%.
Further, as compared with Comparative Examples 6 and 7, molding defects such as delamination do not occur, and molding distortion is reduced.

Claims (6)

It contains the following three components (a), (b), and (c), and the ratio of (b) / (b) is 45/55 to 50/50 (weight ratio), and (b) and (b) B) A thermoplastic elastomer composition obtained by dynamically heat-treating a mixture containing 10 to 18 parts by weight of (C) in the presence of a crosslinking agent at 100 to 400 ° C. (However, a peroxide cross-linked modified olefin resin modified with a group capable of reacting with a hydroxyl group, a carboxyl group or an amino group, and / or a copolymer rubber containing the same, a polyester polymer and a copolymer, A thermoplastic elastomer composition comprising a polyamide polymer and a copolymer, and at least one polymer selected from the group consisting of a polyurethane polymer and a copolymer).
(B) A hydrogenated block copolymer having a weight average molecular weight (hereinafter referred to as “Mw”) of 200,000 to 450,000, wherein the molecular weight in the hydrogenated product of the block copolymer is more than 400,000 A hydrogenated block copolymer represented by the following general formula (1) or (2), wherein the proportion of the polymer is 5% by weight or more and the proportion of the polymer having a molecular weight of 200,000 or less is 20% by weight or less.

In the formula, A is a polymer block composed of monovinyl aromatic hydrocarbon units, B is a polymer block composed of conjugated diene units, and n represents an integer of 1 to 5.
(B) Rubber softener (c) Olefin polymer   2. The block copolymer of component (a) is at least one block copolymer selected from styrene-butadiene block copolymers, styrene-isoprene block copolymers, and styrene-butadiene / isoprene block copolymers. The thermoplastic elastomer composition described in 1.   The thermoplastic elastomer composition according to claim 1 or 2, wherein the rubber softener for component (b) is a mineral oil rubber softener.   The method for producing a thermoplastic elastomer composition according to any one of claims 1 to 3, wherein the olefin polymer of component (c) is a propylene polymer.   The component (c) olefin polymer is at least one olefin polymer selected from the group consisting of a propylene homopolymer, an ethylene / propylene random copolymer, and an ethylene-propylene block copolymer. The thermoplastic elastomer composition described in 1.   The thermoplastic elastomer composition according to any one of claims 1 to 5, wherein the crosslinking agent is used in an amount of 0.1 to 3% by weight based on the total amount of the three components (a), (b) and (c).