JP2012017392A - Thermoplastic elastomer composition and molding of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermoplastic elastomer composition which excels in oil retainability regardless of super-low hardness, in which tackiness nature and compression set are small, and which is further excellent in solvent resistance; and to provide a molding of the same.SOLUTION: The thermoplastic elastomer composition includes (D) 170-270 parts by mass of a non-aromatic rubber softener consisting of: (i) 30-80 mass% of a non-aromatic rubber softener in which the kinetic viscosity at 40°C is at most 90 mm/sec and whose molecular weight distribution (Mw/Mn) measured by a gel permeation chromatography method is at most 1.3; and (ii) 70-20 mass% of a non-aromatic rubber softener in which the kinetic viscosity at 40°C is 350-400 mm/sec and whose molecular weight distribution (Mw/Mn) measured by a gel permeation chromatography method is at most 1.3, based on 100 parts by mass of a resin component which includes (A) 100 parts by mass of a hydrogenated block copolymer which is a hydrogenated block copolymer obtained by carrying out hydrogenation to a block copolymer consisting of at least one of the polymer blocks which use a vinyl aromatic compound as a main component and at least one of the polymer blocks which use a conjugated diene compound as a main component, and whose weight-average molecular weight is 300,000-700,000; (B) 3-15 parts by mass of polypropylene; and (C) 10-200 parts by mass of a polyphenylene ether resin.

Description

  The present invention relates to a hydrogenated block copolymer obtained by hydrogenating a block copolymer comprising a polymer block mainly composed of a vinyl aromatic compound and a polymer block mainly composed of a conjugated diene compound, polypropylene, polyphenylene ether resin, The present invention relates to a thermoplastic elastomer composition containing an aromatic rubber softener and a molded article thereof.

Conventionally, an oil is added as a softening agent to a hydrogenated block copolymer obtained by hydrogenating a block copolymer composed of a polymer block mainly composed of a vinyl aromatic compound and a polymer block mainly composed of a conjugated diene compound. Many thermoplastic elastomer compositions having a predetermined hardness have been developed.
Specifically, 100 parts by mass of a hydrogenated block copolymer having a number average molecular weight of 100,000, 150 parts by mass of a non-aromatic rubber softener having a kinematic viscosity (40 ° C.) of 100 mm ² / sec or more, and polypropylene 12 A thermoplastic elastomer composition containing 5 parts by mass (see Patent Document 1), 100 parts by mass of a hydrogenated block copolymer having a weight average molecular weight of 250,000 or more, and a kinematic viscosity (40 ° C.) of 350 to 400 mm ² / sec. And the thermoplastic elastomer composition which mix | blended 60-170 mass parts of non-aromatic rubber softeners with molecular weight distribution (Mw / Mn) of 1.8 or less, and 12.5-20 mass parts of polypropylene (refer patent document 2). , the hydrogenated block copolymer 100 parts by mass, kinematic viscosity (40 ° C.) is a thermoplastic elastomer composition containing a softening agent 50 to 400 parts by weight of 100~600mm ² / sec ( Patent reference 3), and the like.

JP 2000-169666 A JP 2002-225303 A JP 2003-105311 A

  However, the thermoplastic elastomer compositions disclosed in Patent Documents 1 and 2 have a hardness (JIS A) of 22 degrees and a high tack property, and a thermoplastic elastomer having a very low hardness (12 degrees or less) and a low tack property is Not manufactured. On the other hand, the thermoplastic elastomer composition disclosed in Patent Document 3 has a hardness (JIS A) as low as 4-7. Therefore, the inventors of the present invention tried to produce a thermoplastic elastomer composition according to the example of Patent Document 3, and although it was certainly ultra-low hardness, the softener was slightly bleeded out, and It was found that the quality was not satisfactory and there was room for further improvement.

  As a result of diligent investigation focusing on the above problems, the present inventor has found that a resin component comprising 100 parts by mass of a hydrogenated block copolymer having a predetermined weight average molecular weight, 3 to 15 parts by mass of polypropylene, and 10 to 200 parts by mass of polyphenylene ether resin From a combination of two kinds of predetermined ratios of two types of softeners for non-aromatic rubber having a predetermined kinematic viscosity (40 ° C.) and a molecular weight distribution (Mw / Mn) of a predetermined value or less with respect to 100 parts by mass If the thermoplastic elastomer composition contains 170 to 270 parts by mass of the non-aromatic rubber softener, the non-aromatic is achieved while achieving ultra-low hardness (for example, Shore A hardness = 2 to 12 degrees). The present invention has been completed by finding that the bleed-out of the rubber softener does not occur, has low tackiness, has a small compression set, and is excellent in solvent resistance.

That is, the present invention relates to the following [1] to [5].
[1] (A) Water obtained by hydrogenating a block copolymer comprising at least one polymer block mainly composed of a vinyl aromatic compound and at least one polymer block mainly composed of a conjugated diene compound 100 parts by weight of a hydrogenated block copolymer having a weight average molecular weight of 300,000 to 700,000, 3 to 15 parts by weight of (B) polypropylene, and 10 to 200 parts by weight of (C) a polyphenylene ether resin. (D) (i) The kinematic viscosity at 40 ° C. is 90 mm ² / sec or less and the molecular weight distribution (Mw / Mn) measured by gel permeation chromatography method with respect to 100 parts by mass of the resin component consisting of parts. there is a non-aromatic rubber softener 30 to 80% by weight, and (ii) a kinematic viscosity at 40 ° C., which is a 1.3 350~400mm ² / non-aromatic rubber softening comprising 70 to 20% by mass of a non-aromatic rubber softener that is ec and has a molecular weight distribution (Mw / Mn) of 1.3 or less as measured by gel permeation chromatography A thermoplastic elastomer composition containing 170 to 270 parts by mass of an agent.
[2] In the component (D), the content of the non-aromatic rubber softener as the component (i) is 50 to 70% by mass, and the content of the softener for the non-aromatic rubber as the component (ii) The thermoplastic elastomer composition according to the above [1], wherein the rate is 50 to 30% by mass.
[3] The hydrogenated block copolymer as component (A) is a polystyrene-hydrogenated polybutadiene-polystyrene triblock copolymer, polystyrene-hydrogenated polyisoprene-polystyrene triblock copolymer, and polystyrene-hydrogenated. The thermoplastic elastomer composition according to the above [1] or [2], which is at least one selected from a butadiene / isoprene copolymer-polystyrene triblock copolymer.
[4] The thermoplastic elastomer composition according to any one of [1] to [3], wherein the content of the component (C) in the resin component is 20 to 50 parts by mass.
[5] A molded article obtained by molding the thermoplastic elastomer composition according to any one of [1] to [4].

  According to the present invention, there are provided a thermoplastic elastomer composition and a molded product thereof which are excellent in oil retention despite being ultra-low hardness, have low tackiness and compression set, and are excellent in solvent resistance. can do.

The thermoplastic elastomer composition of the present invention comprises (A) a block copolymer comprising at least one polymer block mainly composed of a vinyl aromatic compound and at least one polymer block mainly composed of a conjugated diene compound. Hydrogenated block copolymer obtained by hydrogenation, 100 parts by weight of hydrogenated block copolymer having a weight average molecular weight of 300,000 to 700,000, (B) 3 to 15 parts by weight of polypropylene, and (C) (D) (i) The molecular weight distribution (Mw) measured by a gel permeation chromatography method with a kinematic viscosity at 40 ° C. of 90 mm ² / sec or less with respect to a resin component consisting of 10 to 200 parts by mass of a polyphenylene ether resin. / Mn) is not more than 1.3, and the non-aromatic rubber softener is 30 to 80% by mass, and (ii) the kinematic viscosity at 40 ° C. is 350. 400mm was ² / sec, and gel permeation molecular weight distribution measured by chromatography molecular weight distribution (Mw / Mn) non-aromatic consisting of non-aromatic rubber softener 70 to 20% by weight is 1.3 or less It contains 170 to 270 parts by mass of a softening agent for rubber, that is, 170 to 270 phr (per hundred resin).

[(A) Hydrogenated block copolymer]
The component (A) is obtained by hydrogenating a block copolymer comprising at least one polymer block mainly composed of a vinyl aromatic compound and at least one polymer block mainly composed of a conjugated diene compound. The weight average molecular weight of the hydrogenated block copolymer needs to be 300,000 to 700,000, preferably 300,000 to 450,000, more preferably 330,000 to 420,000, and even more preferably 350,000 to 400,000. . When the weight average molecular weight of the component (A) is less than 300,000, it cannot withstand the content of the component (D) described later, and the component (D) tends to bleed out from the thermoplastic elastomer composition. The compression set of the resulting thermoplastic elastomer composition is increased. In a hydrogenated block copolymer having a weight average molecular weight of the component (A) exceeding 700,000, processability is remarkably lowered due to deterioration of kneadability.
In addition, in this specification, a weight average molecular weight is the value calculated | required by polystyrene conversion on the basis of the monodispersed polystyrene by the gel permeation chromatography (GPC).

  As a hydrogenated block copolymer obtained by hydrogenating a block copolymer comprising at least one polymer block mainly composed of a vinyl aromatic compound and at least one polymer block mainly composed of a conjugated diene compound Is, for example, a polystyrene-hydrogenated polybutadiene-polystyrene triblock copolymer (hereinafter abbreviated as SEBS), a polystyrene-hydrogenated polyisoprene-polystyrene triblock copolymer (hereinafter abbreviated as SEPS), or polystyrene-. And hydrogenated butadiene / isoprene copolymer-polystyrene triblock copolymer (hereinafter abbreviated as SEEPS). These may be used individually by 1 type and may use 2 or more types together.

In SEBS, the content of the polystyrene block is not particularly limited, but is preferably 10 to 70% by mass, more preferably 20 to 65% by mass. Moreover, there is no restriction | limiting in particular in the hydrogenation rate of a polybutadiene block, However, Preferably it is 50 mol% or more, More preferably, it is 70-100 mol%.
There is no restriction | limiting in particular about the manufacturing method of SEBS, A conventionally well-known method can be used. Moreover, SEBS is marketed and you may use the commercial item whose weight average molecular weight is the said range.

In SEPS, there is no restriction | limiting in particular in the content rate of a polystyrene block, However, Preferably it is 10-70 mass%, More preferably, it is 10-40 mass%. Moreover, there is no restriction | limiting in particular in the hydrogenation rate of a polyisoprene block, However, Preferably it is 50 mol% or more, More preferably, it is 70-100 mol%.
There is no restriction | limiting in particular about the manufacturing method of SEPS, A conventionally well-known method can be used. Moreover, SEPS is marketed and the commercial item whose weight average molecular weight is the said range may be used.

In SEEPS, the content of the polystyrene block is not particularly limited, but is preferably 10 to 70% by mass, more preferably 20 to 40% by mass. Moreover, there is no restriction | limiting in particular in the hydrogenation rate of a butadiene / isoprene copolymer block, However, Preferably it is 50 mol% or more, More preferably, it is 70-100 mol%.
There is no restriction | limiting in particular about the manufacturing method of SEEPS, A conventionally well-known method can be used. Moreover, SEEPS is marketed and you may use the commercial item whose weight average molecular weight is the said range.

[(B) Polypropylene]
Although there is no restriction | limiting in particular in the polypropylene of (B) component, From a viewpoint of a moldability, the melt flow rate (henceforth MFR) measured according to JISK7210 [190 degreeC, 21.18N (2.16kgf)]]. However, it is preferable to use the polyolefin which is 0.1-100 g / 10min, and it is more preferable to use the polyolefin which is 0.5-50g / 10min. Such polypropylene is commercially available. Examples of commercially available products include “NOVATEC (registered trademark) BC05B” (trade name, manufactured by Nippon Polypro Co., Ltd.) and M1600 (trade name, manufactured by Sun Allomer Co., Ltd.). May be used.
(B) Content of a component needs to be 3-15 mass parts with respect to 100 mass parts of (A) component, Preferably it is 3-10 mass parts, More preferably, it is 3-8 mass parts, More preferably 4 to 7 parts by mass. (A) When it is less than 3 parts by mass with respect to 100 parts by mass of the component, when the component (D) that is completely blended in the thermoplastic elastomer composition is kneaded and then cuts the thermoplastic elastomer composition However, the moldability cannot be improved at the same time. Moreover, when it exceeds 15 mass parts with respect to 100 mass parts of (A) component, Shore A hardness will exceed 12 degree | times and a thermoplastic elastomer composition of super-low hardness cannot be obtained.

For the purpose of improving the processability and heat resistance of the thermoplastic elastomer composition, a styrene-based resin can be used in combination with the component (B) polypropylene.
As the styrene resin, those obtained by a known production method can be used, and the styrenic resin may be produced by any of a radical polymerization method and an ionic polymerization method. The weight average molecular weight of the styrene resin is preferably 5,000 to 500,000, more preferably 10,000 to 200,000, and a molecular weight distribution of 5 or less is preferable.
Examples of the styrene resin include polystyrene, styrene-butadiene block copolymer having a styrene unit content of 60% by mass or more, rubber-reinforced polystyrene, poly α-methylstyrene, polypt-butylstyrene, and the like. These may be used individually by 1 type and may use 2 or more types together.
When using together (B) component and a styrene resin, it is preferable that content of the styrene resin with respect to the sum total of (B) component and a styrene resin is 5-15 mass%.

[(C) Polyphenylene ether resin]
By including a polyphenylene ether resin as the component (C) in the thermoplastic elastomer composition of the present invention, the mechanical strength and heat resistance are improved, and the solvent resistance is also improved. In the present specification, the solvent resistance indicates the difficulty of changing the thermoplastic elastomer composition when the thermoplastic elastomer composition is brought into contact with the solvent, and is evaluated by the method described in the examples. be able to. Examples of the solvent include cellosolves such as cellosolve, ethyl cellosolve, and butyl cellosolve; ethers such as dimethyl ether, diethyl ether, dibutyl ether, dibenzyl ether, and polyalkylene glycol monoalkyl ethers such as triethylene glycol monobutyl ether. Cycloalkane such as cyclohexane and cyclooctane; aromatic hydrocarbons such as benzene, ethylbenzene, dichlorobenzene, toluene, xylene and aniline; alcohols such as methanol, ethanol, propanol, isobutyl alcohol and cyclohexanol; pentane, hexane, Aliphatic hydrocarbons such as octane; acetone, methyl ethyl ketone, methyl isobutyl ketone, diisopropyl ketone, acetopheno Ketones such as; ethyl acetate, although esters such as butyl acetate, but is not particularly limited thereto.
The polyphenylene ether resin has the following general formula:

(In the formula, R ¹ , R ² , R ³ and R ⁴ each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms or a phenyl group.)
In the present invention, an alloy with polystyrene, polypropylene or polyamide is also included.
In the general formula, examples of the halogen atom represented by R ^{1 to} R ⁴ include a chlorine atom, a bromine atom, and an iodine atom. Examples of the alkyl group having 1 to 5 carbon atoms represented by R ^{1 to} R ⁴ include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an s-butyl group, a t-butyl group, An n-pentyl group, an isopentyl group, etc. are mentioned.

As the polyphenylene ether resin, known ones can be used. Examples of the homopolymer include poly (2,6-dimethyl-1,4-phenylene ether) and poly (2-methyl-6-ethyl-). 1,4-phenylene ether), poly (2,6-diphenyl-1,4-phenylene ether), poly (2-methyl-6-phenyl-1,4-phenylene ether), poly (2,6-dichloro-) 1,4-phenylene ether). Examples of the copolymer include polyphenylene ether such as a copolymer of 2,6-dimethylphenol and a monovalent phenol (for example, 2,3,6-trimethylphenol or 2-methyl-6-butylphenol). A copolymer etc. are mentioned.
Polyphenylene ether resins are commercially available. Examples of commercially available products include "Zylon (registered trademark)" series manufactured by Asahi Kasei Chemicals Corporation, and "Noryl (registered trademark)" series manufactured by Japan GE Plastics Co., Ltd. These may be used.
(C) Content of a component needs to be 10-200 mass parts with respect to 100 mass parts of (A) component. If it is less than 10 parts by mass, the resulting thermoplastic elastomer composition will have insufficient solvent resistance. On the other hand, if it is 200 parts by mass or more, the hardness will increase so much that it will be difficult to achieve a blend balance, and the desired ultra-low hardness thermoplastic elastomer composition will not be obtained.

[(D) Non-aromatic rubber softener]
In the present invention, as the component (D), (i) the kinematic viscosity (40 ° C.) is 90 mm ² / sec or less, and the molecular weight distribution (Mw / Mn) measured by gel permeation chromatography is 1.3 or less. A non-aromatic rubber softener [hereinafter sometimes referred to as a non-aromatic rubber softener (i) or component (i). And (ii) a non-aromatic system having a kinematic viscosity (40 ° C.) of 350 to 400 mm ² / sec and a molecular weight distribution (Mw / Mn) measured by a gel permeation chromatography method of 1.3 or less. Rubber softener [Hereinafter referred to as non-aromatic rubber softener (ii) or component (ii). ] In combination with a specific ratio. The kinematic viscosity is a value measured according to JIS K2283.
The kinematic viscosity (40 ° C.) of the non-aromatic rubber softener (i) is preferably 5 to 80 mm ² / sec from the viewpoint of tackiness and non-aromatic rubber softener retention (oil retention). , more preferably 10 to 70 mm ² / sec, more preferably 15~60mm ² / sec, more preferably 20 to 50 mm ² / sec. The kinematic viscosity (40 ° C.) of the non-aromatic rubber softener (ii) is preferably 360 to 400 mm ² / sec, more preferably 370 to 400 mm ² / sec, from the viewpoint of tackiness and oil retention. 370 to 390 mm ² / sec is more preferable.
The molecular weight distribution of the non-aromatic rubber softeners (i) and (ii) is preferably 1 to 1.25, more preferably 1 to 1.2.

The ratio of the combination of the non-aromatic rubber softener (i) and the non-aromatic rubber softener (ii) is as follows. Component (ii) 70-20 with respect to 30-80% by mass of component (i) From the viewpoint of tackiness and compression set, the component (ii) is preferably 30 to 30% by mass, more preferably the component (i) 40 to 80, relative to the component (i) 30 to 70% by mass. Component (ii) 60-20% by mass with respect to mass%, more preferably component (ii) 50-20% by mass with respect to component (i) 50-80% by mass, and more preferably component (i) 50-70. It is 50-30 mass% of component (ii) with respect to mass%.
The thermoplastic elastomer composition obtained when the non-aromatic rubber softener (i) and the non-aromatic rubber softener (ii) having the specific kinematic viscosity and molecular weight distribution are not used in the specific ratio. The component (D) may bleed out from the product, the tackiness is increased, the handling property at the time of molding or product transportation is deteriorated, and the compression set is also increased. Occurs.

As the above component (D), for example, paraffinic oil, naphthenic oil, silicone oil, vegetable oil, and the like can be used. Among these, paraffinic oil and silicone oil are preferable from the viewpoint of compatibility, and paraffinic oil is more preferable. These may be used alone or in combination of two or more as long as the compatibility is good.
Examples of the paraffinic oil include “Diana Process Oil PW32” (trade name, manufactured by Idemitsu Kosan Co., Ltd., Mw = 400, Mw / Mn = 1.15, kinematic viscosity (40 ° C.) = 31 mm ² / S, paraffinic oil. For example, “Diana Process Oil PW380” (trade name, manufactured by Idemitsu Kosan Co., Ltd., Mw = 750, Mw / Mn = 1.15, dynamics). Viscosity (40 ° C.) = 380 mm ² / S, paraffin oil) can be used as the non-aromatic rubber softener (ii).
As the silicone oil, commercially available silicone oil and modified silicone oil can be used.
Examples of plant oils include castor oil, cottonseed oil, linseed oil, rapeseed oil, soybean oil, palm oil, coconut oil, peanut oil, wax, pine oil, olive oil and the like.
The content of the component (D) is based on 100 parts by mass of the total of the components (A) to (C), which are resin components, from the viewpoint of suppressing bleed-out while making the thermoplastic elastomer composition extremely low in hardness. It is necessary to be 170 to 270 parts by mass, preferably 175 to 270 parts by mass, and more preferably 180 to 260 parts by mass.

[Other ingredients]
In producing the thermoplastic elastomer composition of the present invention, other additives may be further contained in addition to the components (A) to (D) as long as the object of the present invention is not impaired.
Examples of such additives include ceramic, carbon black, amber, senna, kaolin, nickel titanium yellow, cobalt blue, plamaster gray, quinophthalone, diketopyrrolopyrrole, quinacridone, dioxazine, phthalocyanine blue, and phthalocyanine green. Flame retardant: Anti-aging agent: Antistatic agent: Antibacterial agent: Antioxidant: Inorganic hollow fillers such as talc, silica, calcium carbonate, magnesium carbonate, aluminum hydroxide, barium sulfate, glass fiber, glass powder, glass balloon, ceramic powder Inorganic fillers such as mica, organic fillers such as cork powder, wood powder and graphite: Release agents such as stearic acid: Light stabilizers: Tackifiers such as rosin derivatives (tackfire): “Rheostomer® ) B (Trade name, Riken Technos Co., Ltd.) adhesive elastomers, such as: coumarone resins, coumarone - indene resins, and phenolic terpene resins.
When the additive is contained, the content thereof is preferably 20 parts by mass or less and more preferably 5 parts by mass or less with respect to 100 parts by mass of the component (A).

Furthermore, the thermoplastic elastomer composition of the present invention can be partially crosslinked by adding a crosslinking agent or a crosslinking aid.
As a crosslinking agent, an organic peroxide is preferable. Specific examples of the organic peroxide include 2,5-dimethyl-2,5-di (t-butylperoxy) -hexane; 2,5-dimethyl-2,5-di (benzoylperoxy) -hexane; t -Butylperoxybenzoate; Dicumyl peroxide; t-Butylcumyl peroxide; Diisopropylbenzohydroperoxide; 1,3-bis- (t-butylperoxyisopropyl) -benzene; Benzoyl peroxide; 1,1-di And (t-butylperoxy) -3,3,5-trimethylcyclohexane.
Examples of the crosslinking aid include divinylbenzene, trimethylolpropane triacrylate, ethylene dimethacrylate, diallyl phthalate, quinone dioxime, phenylene bismaleimide, polyethylene glycol dimethacrylate, and unsaturated silane compounds.
A crosslinking agent and a crosslinking aid may be used individually by 1 type, and may use 2 or more types together, respectively.
When using a crosslinking agent and a crosslinking aid, the degree of crosslinking can be adjusted by arbitrarily using 0.1 to 5 parts by mass with respect to 100 parts by weight of the thermoplastic elastomer composition.
In addition, when an unsaturated silane compound is used as a crosslinking aid, the crosslinking can be further advanced by contacting with moisture in the presence of a silanol condensation catalyst.

(Method for preparing thermoplastic elastomer composition)
The components (A) to (D) and the above-mentioned additives and the like are mixed, and for example, preferably using a single-screw kneader, a twin-screw kneader, a Banbury mixer, a brabender, a kneader, a high shear mixer, etc. A thermoplastic elastomer composition can be obtained by melt-kneading at 100 to 300 ° C, more preferably 150 to 230 ° C.
In particular, in order to sufficiently mix the non-aromatic rubber softening agent (D) with each component, there is no particular limitation, but for example, the following method may be used.
A twin-screw kneader having a “screw total length / cylinder diameter” of 30 or more, preferably 50 to 70, and a ratio of the length of the kneading zone to the screw full length of 30% or more, preferably 40 to 70% is prepared. In advance, a part or all of the component (D) is added to and mixed with the component (A), the component (B) and the component (C) and, if necessary, the additive. Feeding from the polymer inlet, and if there is a remaining component (D), feed from the polymer inlet or side feed port and melt-knead to sufficiently mix the component (D) into the composition. Get difficult pellets.
In addition, in advance, a part or all of the component (D) is not added to the component (A), the component (B) and the component (C) and the additive as necessary, At the same time, it may be fed from the polymer inlet.

Although the thermoplastic elastomer composition of the present invention thus obtained has an extremely low hardness (Shore A hardness of about 2 to 12 degrees), there is no or very little bleeding out of the component (D). In the present invention, the Shore A hardness can be 2 to 11 degrees, and preferably 2 to 10 degrees, more preferably 2 to 9 degrees, if necessary.
The thermoplastic elastomer composition of the present invention has a compression set of 35% or less (30 to 35%), low tackiness, and excellent oil retention and solvent resistance. All were measured and evaluated by the methods described in the examples.

  Using the thermoplastic elastomer composition obtained as described above, a molded article can be produced by a molding method and a molding apparatus generally employed for the thermoplastic elastomer composition. Specifically, a molded body can be produced by extrusion molding, injection molding, press molding, blow molding or the like.

  EXAMPLES Next, although an Example demonstrates this invention still in detail, this invention is not limited at all by these examples.

<Examples 1-8, Comparative Examples 1-12>
Each component was mixed in advance in the blending amounts (unit: parts by mass) shown in Tables 1 to 3, and then a twin-screw kneader (manufactured by Toshiba Machine Co., Ltd., TEM58BS type, screw overall length / cylinder diameter = 62.5, screw overall length) Kneaded at 180 ° C. at a kneading zone length ratio to 62%) and cut with a cutter while extruding into strands to obtain pellets of a thermoplastic elastomer composition. The resulting pellets were measured and evaluated for Shore A hardness, compression set, tackiness, solvent resistance and oil retention as follows. The results are shown in Tables 1-3.

(1) Shore A hardness Measured according to JIS K6253 (type A).
(2) Compression set In accordance with JIS K6262, a test piece having a diameter of 13 mm and a thickness of 6 mm was used. The compression set is preferably small.
(3) Tackiness A cylindrical probe made of SUS304 is pressed on the surface of a 2 mm thick sheet formed from a thermoplastic elastomer composition under the following conditions, and the force when pulling up the probe is measured to measure tackiness. It was.
-Probe pressing conditions-
Probe diameter: 3mm
Measurement temperature: 23 ° C
Indentation speed: 2.5 mm / min Indentation load-time: 14 gf-1 second (0.137N-1 second)
Lifting speed: 120mm / min

(4) Solvent resistance Three sheets (60 mm, 10 mm, thickness 2 mm) formed from a thermoplastic elastomer composition were bent at a bending radius R = 10 mm, and then an aqueous solution of 5% by mass of triethylene glycol monobutyl ether at 70 ° C. And the presence of cracks was investigated and evaluated according to the following evaluation criteria.
○: After one week, no cracks occurred on all three sheets.
X: Some cracks occurred within one week.
(5) Oil retention The sheet | seat (25 mm in diameter, thickness 2mm) which shape | molded the thermoplastic elastomer composition was pinched | interposed into the iron plate, and it compressed at 70 degreeC for 48 hours by 50% compression. The sheet mass reduction ratio before and after compression was measured and used as an index of the retention (oil retention) of the non-aromatic rubber softener possessed by the thermoplastic elastomer composition. Evaluation was performed as follows.
○: Change rate of 3% or less.
Δ: Change rate exceeds 3% and less than 5%.
X: Change rate of 5% or more.

1): “Septon (registered trademark) 4077”, SEEPS, Mw = 350,000, polystyrene block content 30%, manufactured by Kuraray Co., Ltd. 2): “Septon (registered trademark) 4099”, SEEPS, Mw = 400,000, polystyrene Block content 30%, Kuraray Co., Ltd. 3): “Diana Process Oil PW32”, paraffinic oil, Mw = 400, Mw / Mn = 1.15, kinematic viscosity (40 ° C.) = 31 mm ² / sec, Idemitsu Kosan 4): “Diana Process Oil PW380”, paraffinic oil, Mw = 750, Mw / Mn = 1.15, kinematic viscosity (40 ° C.) = 380 mm ² / sec, Idemitsu Kosan Co., Ltd. 5): “ Diana Process Oil PW90 ”, paraffinic oil, Mw = 530, Mw / Mn = 1.15, kinematic viscosity (40 ° C.) = 96 m ² / sec, manufactured by Idemitsu Kosan Co., Ltd. 6): "Lucant (registered trademark) HC-100", a paraffin-based oil, Mw = 1450, Mw / Mn = 1.4, a kinematic viscosity ^{(40 ℃) = 1700mm 2 /} sec 7) manufactured by Mitsui Chemicals, Inc .: “Novatech (registered trademark) BC05B”, MFR = 50 (g / 10 minutes), manufactured by Nippon Polypro Co., Ltd. 8): “Zylon (registered trademark) X0108”, softening point 160 ° C. Asahi Kasei Chemicals Corporation

As shown in Table 1, the thermoplastic elastomer composition of the present invention has low compression set and tackiness and is excellent in solvent resistance. In addition, in all cases, the Shore A hardness is in the range of 2 to 12, and the oil retention is excellent despite the ultra low hardness.
On the other hand, as Comparative Examples 1-8 showed, when there was little content of the polyphenylene ether resin of (C) component, solvent resistance deteriorated. Further, as shown in Comparative Examples 9 to 12, when only one of the non-aromatic rubber softener (i) or (ii) is used, or the non-aromatic rubber softener (i) or When a non-aromatic rubber softener not corresponding to (ii) was used, an increase in tackiness, an increase in compression set, deterioration in solvent resistance, deterioration in oil retention, etc. were observed.

  The thermoplastic elastomer composition of the present invention has characteristics such as high oil retention, low tackiness and compression set, and excellent solvent resistance despite being designed for ultra-low hardness. For example, it can be used for applications such as a sealing material, a gasket material, an anti-vibration material, an impact absorbing material, a cover material (for example, a cover material for ink for an ink jet printer), and a buffer material.

Claims (5)

(A) A hydrogenated block copolymer obtained by hydrogenating a block copolymer comprising at least one polymer block mainly composed of a vinyl aromatic compound and at least one polymer block mainly composed of a conjugated diene compound. A polymer comprising 100 parts by mass of a hydrogenated block copolymer having a weight average molecular weight of 300,000 to 700,000, (B) 3 to 15 parts by mass of polypropylene, and (C) 10 to 200 parts by mass of a polyphenylene ether resin. (D) (i) The kinematic viscosity at 40 ° C. is 90 mm ² / sec or less and the molecular weight distribution (Mw / Mn) measured by the gel permeation chromatography method is 1. 3 30 to 80 wt% non-aromatic rubber softener is less and (ii) a kinematic viscosity at 40 ° C. is 350~400mm ² / sec And a non-aromatic rubber softener 170 comprising 70 to 20% by weight of a non-aromatic rubber softener having a molecular weight distribution (Mw / Mn) of 1.3 or less as measured by gel permeation chromatography. A thermoplastic elastomer composition containing 270 parts by mass.   In the component (D), the content of the non-aromatic rubber softener as the component (i) is 50 to 70% by mass, and the content of the non-aromatic rubber softener as the component (ii) is 50. The thermoplastic-elastomer composition of Claim 1 which is -30 mass%.   The hydrogenated block copolymer as component (A) is a polystyrene-hydrogenated polybutadiene-polystyrene triblock copolymer, a polystyrene-hydrogenated polyisoprene-polystyrene triblock copolymer, and a polystyrene-hydrogenated butadiene / isoprene. The thermoplastic elastomer composition according to claim 1 or 2, which is at least one selected from a copolymer-polystyrene triblock copolymer.   The thermoplastic elastomer composition according to any one of claims 1 to 3, wherein the content of the component (C) in the resin component is 20 to 50 parts by mass.   The molded object obtained by shape | molding the thermoplastic elastomer composition in any one of Claims 1-4.