JP2002234985A - Thermoplastic elastomer composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermoplastic elastomer composition excellent in flexibility, (short-term and long-term) compression strain and oil resistance, and suppressed in bleeding out of a softening agent. SOLUTION: The thermoplastic elastomer composition is obtained by melt- kneading a composition comprising (a) 100 pts.wt. of a hydrogenated block copolymer obtained by hydrogenating a block copolymer comprising at least two polymer blocks A mainly composed of an aromatic vinyl compound and at least one polymer block B mainly composed of isoprene, (b) 50-250 pts.wt. of a softening agent for a non-aromatic rubber, (c) 2-80 pts.wt. of a peroxide- decomposable olefinic resin, (d) 0.1-125 pts.wt. of a liquid polybutadiene, and (e) 0.01-1.25 pts.wt. of an organic peroxide.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermoplastic elastomer composition and, more particularly, to a thermoplastic elastomer having excellent flexibility, (short-term and long-term) compression set, oil resistance, and suppressing bleed-out of a softener. Composition.

[0002]

2. Description of the Related Art In recent years, thermoplastic elastomers, which are soft materials having rubber elasticity, do not require a vulcanization step, and are moldable and recyclable similar to thermoplastic resins, have been used for automobile parts, home electric parts, It is widely used in the fields of wire coating, medical parts, footwear, sundries and the like.

[0003] Among thermoplastic elastomers, polystyrene-based thermoplastics such as styrene-butadiene block copolymer (SBS) and styrene-isoprene block copolymer (SIS), which are block copolymers of an aromatic vinyl compound and a conjugated diene compound, are used. A thermoplastic elastomer is rich in flexibility, has good rubber elasticity at room temperature, and the thermoplastic elastomer composition obtained therefrom has excellent processability and is widely used as a substitute for vulcanized rubber. .

Further, elastomer compositions obtained by hydrogenating an intramolecular double bond of a block copolymer of styrene and a conjugated diene in these elastomers are elastomers having improved heat aging resistance (thermal stability) and weather resistance. As is widely used.

[0005] However, thermoplastic elastomer compositions using these hydrogenated block copolymers still have rubber-like properties such as oil resistance, deformation under heating and compression (compression set) and rubber elasticity at high temperatures. There is a problem, and as a solution to this problem, a crosslinked product obtained by crosslinking a composition containing a hydrogenated derivative of the above block copolymer has been proposed (for example, JP-A-59-6236, JP-A-63-57662, JP-B-3-49927, JP-B3-111291 and JP-B6-136.
No. 28).

[0006] However, the crosslinked composition of the hydrogenated block copolymer disclosed in the above-mentioned publication is not suitable for high temperature,
There is a problem that the compression set at 00 ° C. is still insufficient, and the mechanical strength is liable to be lowered. At present, it has not yet reached the performance level required for vulcanized rubber applications. Extrusion molding also has many problems with molding surfaces, such as poor shape retention due to low melt tension at high temperatures and injection molding with a long molding cycle.

[0007] The compositions disclosed in the above publications all have a Shore A hardness of 40 or more and are softened by increasing the amount of a softening agent added. At present, there is a problem that stickiness occurs on the surface and bleed out of the softener under heating stress, which is not preferable in practical use.

[0008]

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide flexibility, short-term and long-term compression set,
An object of the present invention is to provide a thermoplastic elastomer composition having excellent oil resistance and suppressing bleed-out of a softener.

[0009]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the present inventors have found that a specific hydrogenated styrene-based elastomer is subjected to a crosslinking treatment in the presence of liquid polybutadiene to provide a flexible material. Properties, compression set,
The present inventors have found that a thermoplastic elastomer composition having excellent oil resistance and heat aging resistance and suppressing bleeding out of a softener can be obtained, and completed the present invention.

That is, the first invention of the present invention provides (a)
At least two polymer blocks A mainly composed of an aromatic vinyl compound and at least one polymer block A mainly composed of isoprene;
100 parts by weight of a hydrogenated block copolymer obtained by hydrogenating a block copolymer consisting of individual polymer blocks B, (b) 50 to 250 parts by weight of a softener for non-aromatic rubber, (c) Peroxide decomposition type olefin resin 2
80 parts by weight, (d) liquid polybutadiene 0.1 to 125
It is a thermoplastic elastomer composition obtained by melt-kneading a composition containing 0.01 to 1.25 parts by weight of (e) an organic peroxide.

The second invention of the present invention relates to (a) the hydrogenated block copolymer, wherein 70 to 100% by weight of isoprene in the polymer block B has a 1,4-micro structure; At least 90% of the isoprene-based double bonds are hydrogenated, the polymer block A is 5 to 70% by weight of the entire component (a), and the weight average molecular weight of the entire block copolymer is 50, 000 to 550,000. The thermoplastic elastomer composition according to the first aspect of the present invention.

A third invention of the present invention is the thermoplastic elastomer composition according to the first or second invention, wherein (b) the softener for non-aromatic rubber is polybutene. .

A fourth aspect of the present invention provides the thermoplastic elastomer composition according to any one of the first to third aspects, further comprising (f) 0.1 to 50 parts by weight of a silicone oil. Things.

The fifth invention of the present invention is characterized in that (g) 0.1 to 50 parts by weight of an ester-based crosslinking aid is further contained, and It is a plastic elastomer composition.

According to a sixth aspect of the present invention, there is provided an elastic member for bottle cap packing and an elasticity for an ink jet recording apparatus, comprising the thermoplastic elastomer composition according to any one of the first to fifth aspects. It is a member.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below in detail for each component, production method and the like.

1. Constituents (1) Component (a) hydrogenated block copolymer The component (a) hydrogenated block copolymer used in the present invention comprises at least two polymer blocks A mainly composed of an aromatic vinyl compound, and isoprene. Is a polymer obtained by hydrogenating a block copolymer consisting mainly of at least one polymer block B. For example, ABA,
It is obtained by hydrogenating an aromatic vinyl compound-isoprene block copolymer having a structure such as BABA, ABAABA or the like.

The polymer block A mainly composed of an aromatic vinyl compound may be a polymer consisting of only an aromatic vinyl compound or a copolymer of an aromatic vinyl compound and less than 50% by weight of a conjugated diene compound. Good. The polymer block B mainly composed of isoprene may be a polymer composed of only isoprene or a copolymer of isoprene and less than 50% by weight of an aromatic vinyl compound.

In each of the polymer block A mainly composed of the aromatic vinyl compound and the polymer block B mainly composed of isoprene, the distribution of the vinyl compound or isoprene in the molecular chain is random, tapered or partially blocked. Or any combination thereof. When there are two or more polymer blocks mainly composed of an aromatic vinyl compound or polymer blocks mainly composed of isoprene, they may have the same structure or different structures.

Examples of the aromatic vinyl compound include styrene, α-methylstyrene, vinyltoluene, p-tert-butylstyrene and the like, and they may be used alone or as a mixture of two or more. Of these, styrene is preferred. As the optional conjugated diene compound in the polymer block A, for example, butadiene, isoprene, 1,3-
Examples thereof include pentadiene and 2,3-dimethyl-1,3-butadiene, which may be used alone or in combination of two or more. Of these, butadiene, isoprene and combinations thereof are preferred.

In the hydrogenated block polymer (a), 70 to 100% by weight, particularly 90 to 100% by weight of isoprene in the polymer block B mainly composed of isoprene has a 1,4-micro structure. Preferred are those in which at least 90% of the double bonds based on isoprene are hydrogenated. Further, the polymer block A is composed of 5 (a)
Preferably it is present in a proportion of up to 70% by weight. further,
The weight average molecular weight of the entire component (a) is from 50,000 to 5
Those which are 50,000 are preferred.

Specific examples of the hydrogenated block polymer as the component (a) include styrene-ethylene-propylene-styrene copolymer (SEPS) and styrene-ethylene-ethylene-propylene-styrene copolymer (SEEPS). Can be mentioned.

Numerous methods have been proposed as methods for producing these block copolymers. Representative methods include, for example, the method described in Japanese Patent Publication No. 23798/1971 using a lithium catalyst or Ziegler catalyst. It can be obtained by performing block polymerization in an inert medium using a type catalyst. The hydrogenation treatment of such a block copolymer can be performed by a known method in an inert solvent in the presence of a hydrogenation catalyst.

(2) Component (b) Softener for Non-Aromatic Rubber The softener for non-aromatic rubber which can be used as the component (b) in the present invention is a non-aromatic mineral oil or liquid. Alternatively, a low molecular weight synthetic softener can be used. The mineral oil softener used for rubber is a mixture of an aromatic ring, a naphthene ring, and a paraffin chain in which the number of carbon atoms in the paraffin chain accounts for 50% or more of the total number of carbon atoms. Those having a naphthene ring carbon number of 30 to 40% are called naphthenics, and those having an aromatic carbon number of 30% or more are called aromatics.

The mineral oil-based rubber softeners used as the component (b) of the present invention are classified into paraffinic and naphthenic types. The use of an aromatic softening agent is not preferred because its use makes the component (a) soluble and inhibits the cross-linking reaction, so that the physical properties of the obtained composition cannot be improved. As the component (b) of the present invention, a paraffin-based component is preferable, and among the paraffin-based components, those having less aromatic ring components are particularly suitable. In addition, as a liquid or low molecular weight synthetic softener, polybutene, hydrogenated polybutene,
And low molecular weight polyisobutylene. Of these, polybutene or hydrogenated polybutene is preferred.

The properties of these softeners for non-aromatic rubbers are such that the dynamic viscosity at 37.8 ° C. is 20 to 50,000 c.
St, dynamic viscosity at 100 ° C. is 5 to 1500 cs
t, pour point is -10 to -15 ° C, flash point (COC) is 1
It is preferably between 70 and 300 ° C. Further, those having a weight average molecular weight of 100 to 2,000 are preferred.

The amount of component (b) is 100 parts (a)
It is 50 to 250 parts by weight, preferably 80 to 200 parts by weight, based on parts by weight. When the amount is less than 50 parts by weight, the moldability of the obtained elastomer composition is deteriorated, and the hardness of the elastomer composition becomes too high, the flexibility is lost, and a rubber-like product cannot be obtained. If the amount exceeds 250 parts by weight, the softener tends to bleed out from the obtained elastomer composition, and peeling, deformation and flow marks tend to occur on the molded article.

(3) Component (c) Peroxide-decomposable olefin-based resin The peroxide-decomposable olefin-based resin used as the component (c) in the present invention can improve the rubber dispersion of the obtained composition and improve the quality of the molded product. It not only improves the appearance but also has the effect of adjusting the hardness and shrinkage. The component is an olefin-based polymer or copolymer that is thermally decomposed by heating in the presence of a peroxide to appropriately reduce the molecular weight and increase the fluidity at the time of melting, for example, isotactic. Polypropylene and propylene and other α-
Copolymers with olefins, for example, ethylene, 1-butene, 1-hexene, 4-methyl-1-pentene, 1-octene and the like can be mentioned.

The D of the homo moiety of the olefin copolymer
The melting point by SC measurement is preferably such that Tm is 150 to 1
67 ° C., ΔHm is in the range of 25 to 83 mJ / mg. The crystallinity can be estimated from Tm and ΔHm measured by DSC. When Tm and ΔHm are out of the above ranges, oil resistance and rubber elasticity at 100 ° C. or higher of the obtained elastomer composition are not improved.

The melt flow rate of the component (c) (MFR, ASTM D-1238, L condition, 230
C) is preferably 0.1 to 200 g / 10 min, more preferably 0.5 to 100 g / 10 min. When the MFR is less than 0.1 g / 10 minutes, the moldability of the obtained elastomer composition is reduced, and when it exceeds 200 g / 10 minutes, the rubber elasticity of the obtained elastomer composition is deteriorated.

The amount of the component (c) is 100%.
2 to 80 parts by weight, preferably 1 part by weight
0 to 60 parts by weight. If the compounding amount is less than 2 parts by weight, the moldability of the obtained elastomer composition is deteriorated, and peeling, deformation and flow marks are liable to occur on the molded product. If it exceeds 80 parts by weight, the moldability of the obtained elastomer composition will be poor, and the hardness of the elastomer composition will be too high, and the flexibility will be lost, so that a rubber-like product cannot be obtained.

(4) Component (d) Liquid polybutadiene The liquid polybutadiene used as the component (d) in the present invention is:
When the elastomer composition is melt-processed, the polymer is mainly graft-polymerized to the component (a) in the presence of a peroxide, and exerts an effect of suppressing bleed-out of the softener in the elastomer composition. The liquid polybutadiene component is a liquid polymer that is transparent at room temperature and has a main chain fine structure of vinyl 1,2-bond, trans 1,4-bond, and cis 1,4-bond. Here, the vinyl 1,2-bond is preferably 30% by weight or less,
A vinyl 1,2-bond content of more than 30% by weight is not preferred because the low-temperature properties of the resulting composition deteriorate.

The number average molecular weight of the liquid polybutadiene is preferably from 1,000 to 5,000, more preferably from 2,000 to 4,000. Number average molecular weight is 1,
If it is less than 000, the resulting composition will have reduced thermal deformation resistance, and if it exceeds 5,000, the compatibility of the obtained composition will be reduced.

Further, the liquid polybutadiene may be a copolymerizable compound having one or more groups selected from an epoxy group, a hydroxyl group, an isocyanate group and a carboxyl group. Among them, those having a hydroxyl group and a copolymerization-reactive unsaturated double bond are particularly preferred. Commercially available products include, for example, R-45HT manufactured by Idemitsu Petrochemical Co., Ltd.
(Trademark).

The amount of component (d) is 100 parts (a)
0.1 to 125 parts by weight, preferably 1 to 80 parts by weight, more preferably 1 to 80 parts by weight with respect to parts by weight.
40 parts by weight. If the amount is less than 0.1 part by weight, the hardness of the elastomer composition becomes too high, the flexibility is lost, and a rubber-like product cannot be obtained, and the abrasion resistance of the molded product decreases. If the amount exceeds 125 parts by weight, bleed-out of the softener tends to occur, and the molded product may become sticky and the elastomer composition may have an odor.

(5) Component (e) Organic Peroxide The component (e) organic peroxide of the present invention generates radicals and reacts the radicals in a chain to form the component (a).
And at the same time, decomposes component (d) to increase the fluidity of the composition during melt-kneading, thereby improving the dispersion of the rubber component, and further to convert component (d) into component (a).
It has the function of graft polymerization. As the 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)
Hexin-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-butylperoxybenzoate, tert-butylperoxyisopropyl carbonate, diacetyl peroxide, lauroyl peroxide, tert-butylcumyl peroxide and the like. it can. Among these, from the viewpoint of odor, coloring, and scorch safety, 2,5-dimethyl-
2,5-Di- (tert-butylperoxy) hexane and 2,5-dimethyl-2,5-di- (tert-butylperoxy) hexyne-3 are particularly preferred.

The amount of component (e) is 100 parts (a)
It is 0.01 to 1.25 parts by weight, preferably 0.05 to 1.0 part by weight, based on parts by weight. If the amount is less than 0.01 part by weight, crosslinking cannot be sufficiently achieved, and the heat resistance and mechanical strength of the obtained elastomer are low. On the other hand, if it exceeds 1.25 parts by weight, the moldability will deteriorate.

(6) Component (f) Silicone Oil In the elastomer composition of the present invention, component (f) silicone oil can be blended if necessary. Component (f) exhibits an effect of improving the surface tackiness of a molded article using the elastomer composition of the present invention. Examples of the component include dimethyl silicone oil, methylphenyl silicone oil, methyl hydrogen silicone oil, and a modified silicone oil containing another organic group. The weight average molecular weight of the silicone oil is preferably from 5,000 to 50,000, and more preferably from 10,000 to 20,000. If the weight-average molecular weight is less than 5,000, bleed-out becomes remarkable. The viscosity of the silicone oil is 100 to
1,000 cSt is appropriate.

The amount of component (f) is preferably 0.1 to 50 parts by weight, more preferably 0.5 to 30 parts by weight, based on 100 parts by weight of component (a), if necessary. It is. Even if the amount is more than 50 parts by weight, there is little further improvement, and bleed out becomes remarkable.

(7) Component (g) Ester Crosslinking Aid In the elastomer composition of the present invention, a component (g) ester crosslinking aid can be blended as required. The component (g) can be blended during the above-mentioned (e) crosslinking treatment with an organic peroxide in the production of the elastomer composition, whereby a uniform and efficient crosslinking reaction can be carried out.

As the component (g), for example, triallyl cyanurate, ethylene glycol dimethacrylate,
Diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, polyethylene glycol dimethacrylate having 9 to 14 ethylene glycol repeating units, trimethylolpropane trimethacrylate, allyl methacrylate, 2-methyl-1,8-octane Polyfunctional methacrylate compounds such as diol dimethacrylate, 1,9-nonanediol dimethacrylate,
Examples include polyfunctional acrylate compounds such as polyethylene glycol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, propylene glycol diacrylate, and polyfunctional vinyl compounds such as vinyl butyrate or vinyl stearate. be able to. These may be used alone or in combination of two or more. Among the above crosslinking aids, a polyfunctional acrylate compound or a polyfunctional methacrylate compound is preferable, and triethylene glycol dimethacrylate and tetraethylene glycol dimethacrylate are particularly preferable. These compounds are easy to handle, have a solubilizing effect on organic peroxides, and work as a dispersing aid for organic peroxides, so that crosslinking by heat treatment is uniform and effective, and hardness and rubber elasticity are improved. Is obtained.

The amount of the component (g) is as follows:
The amount is preferably 0.1 to 50 parts by weight, more preferably 0.1 to 30 parts by weight, based on 100 parts by weight of the component (a). If the compounding amount exceeds 50 parts by weight, the degree of cross-linking is reduced due to self-polymerization, and the effect cannot be obtained.

(8) Component (h) Block Copolymer In the elastomer composition of the present invention, a component (h) block copolymer can be blended if necessary. The block copolymer as the component (h) is a block copolymer composed of at least two polymer blocks A mainly composed of an aromatic vinyl compound and at least one polymer block B ′ mainly composed of a conjugated diene compound. It is united. For example, AB'-A, B'-AB'-
A, an aromatic vinyl compound-conjugated diene compound block copolymer having a structure such as AB′-AB′-A.

The block copolymer as a whole preferably contains 5 to 60% by weight, particularly preferably 20 to 50% by weight, of an aromatic vinyl compound. The polymer block A mainly composed of an aromatic vinyl compound is preferably 50% by weight or more, particularly preferably 70% by weight or more of an aromatic vinyl compound, and a homopolymer or an optional component such as a conjugated diene compound. It is a copolymer block. The polymer block B ′ mainly composed of a conjugated diene compound is preferably 50% by weight or more, particularly preferably 70% by weight or more of a conjugated diene compound, and a homopolymer or an optional component such as an aromatic vinyl compound. It is a copolymer block. Further, in the polymer block A mainly composed of the aromatic vinyl compound and the polymer block B ′ mainly composed of the conjugated diene compound, the distribution of units derived from the conjugated diene compound or the aromatic vinyl compound in the molecular chain is random. , Tapered (the monomer component increases or decreases along the molecular chain), partially block-shaped, or any combination thereof. When there are two or more polymer blocks A mainly containing an aromatic vinyl compound or two or more polymer blocks B ′ mainly containing a conjugated diene compound, each polymer block has a different structure even if they have the same structure. It may be.

As the aromatic vinyl compound constituting the block copolymer, for example, one or more of styrene, α-methylstyrene, vinyltoluene, p-tert-butylstyrene and the like can be selected. However, styrene is preferred. Examples of the conjugated diene compound include butadiene, isoprene, 1,3-pentadiene, 2,3
One or more kinds are selected from -dimethyl-1,3-butadiene and the like, and among them, butadiene, isoprene and a combination thereof are preferable.

Specific examples of the above block copolymer include:
Styrene-butadiene-styrene copolymer (SBS),
Styrene / isoprene / styrene copolymer (SIS) and the like.

The amount of the component (h) is as follows:
The amount is preferably from 1 to 100 parts by weight, more preferably from 1 to 60 parts by weight, per 100 parts by weight of the component (a). 10
If the amount exceeds 0 parts by weight, mechanical properties, compression set and injection moldability deteriorate.

(9) Component (i) Olefin Copolymer Rubber In the elastomer composition of the present invention, component (i) olefin copolymer rubber can be blended if necessary. The component (i) mainly causes a cross-linking reaction by heating in the presence of an organic peroxide, and reduces the fluidity thereof, thereby controlling the hardness and shrinkage of the thermoplastic elastomer composition of the present invention. It is effective. In the present invention, as the olefin-based copolymer rubber that can be used, ethylene-propylene copolymer rubber,
Examples include an ethylene / butene copolymer rubber and an ethylene / propylene / non-conjugated diene copolymer rubber.

The amount of the component (i) is
The amount is preferably from 1 to 100 parts by weight, more preferably from 1 to 60 parts by weight, per 100 parts by weight of the component (a). If the compounding amount exceeds 100 parts by weight, mechanical properties, compression set and injection moldability deteriorate.

(10) Component (j) Inorganic Filler In the elastomer composition of the present invention, component (j) inorganic filler can be blended if necessary. Component (j) has the effect of improving some physical properties such as compression set of a molded article obtained from the elastomer composition,
It has the economic benefits of weight gain. Component (j) includes calcium carbonate, talc, silica, diatomaceous earth, barium sulfate, magnesium carbonate, magnesium hydroxide, mica, clay, titanium oxide, carbon black, glass fiber, hollow glass balloon, carbon fiber, calcium titanate fiber , Natural silica, synthetic silica (white carbon)
And the like. Of these, calcium carbonate and talc are particularly preferred.

The amount of component (j) is
The amount is preferably 1 to 100 parts by weight, more preferably 1 to 50 parts by weight, based on 100 parts by weight of the component (a). If the amount is more than 100 parts by weight, the mechanical strength of the obtained elastomer composition will be remarkably reduced, and the hardness will be high, the flexibility will be lost, and a rubbery product cannot be obtained.

(11) Other components (k) In addition to the above components, the elastomer composition of the present invention may further contain, if necessary, various antiblocking agents.
It may also contain a sealability improver, a heat stabilizer, an antioxidant, a light stabilizer, an ultraviolet absorber, a lubricant, a crystal nucleating agent, a colorant, and the like. Here, as the antioxidant, for example,
2,6-di-tert-p-butyl-p-cresol,
Phenols such as 2,6-di-tert-butylphenol, 2,4-dimethyl-6-tert-butylphenol, 4,4-dihydroxydiphenyl, tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane Antioxidants, phosphite antioxidants, thioether antioxidants, and the like. Of these, phenolic antioxidants and phosphite antioxidants are particularly preferred. The antioxidant is preferably used in an amount of 0 to 3.0 parts by weight, particularly preferably 0.1 to 1.0 part by weight, based on 100 parts by weight of the components (a) to (i) in total.

2. Production of Thermoplastic Elastomer Composition The thermoplastic elastomer composition of the present invention comprises the above components (a) to (e) or, if necessary, components (f) to (k)
And then melt-kneading the components simultaneously or in an arbitrary order.

The method of melt kneading is not particularly limited, and a generally known method can be used. For example, a single-screw extruder, a twin-screw extruder, a roll, a Banbury mixer, various kneaders, or the like can be used. For example, a moderate L / D twin screw extruder,
The above operation can be performed continuously by using a Banbury mixer, a pressure kneader, or the like. Here, the temperature of the melt-kneading is preferably 160 to 220 ° C.

3. Uses of the thermoplastic elastomer composition The thermoplastic elastomer composition of the present invention has moderate flexibility, excellent permanent compression strain, particularly excellent compression strain of 70 ° C or less, and furthermore, has an excessive stress deformation and Even when used under a load, there is little bleed-out of the softening agent, so that there is a feature that the environment is not polluted.

Therefore, the thermoplastic elastomer composition of the present invention can be used as a material for electric parts, a bottle cap packing,
It can be used as a seal member for automobiles, a multicolor molded seal member with a polyolefin or a hard thermoplastic elastomer, and particularly useful as an ink leak seal member in an ink jet recording apparatus or the like.

[0057]

The present invention will be described in detail with reference to the following examples and comparative examples. In addition, the measurement of the physical property was performed using the following methods. (1) Hardness: According to JIS K 7215, the test piece was a 6.3 mm-thick pressed sheet, and had a durometer hardness
It was measured by type A. (2) Tensile strength: According to JIS K 6301, a test piece was prepared by punching a 1 mm thick press sheet into a No. 3 dumbbell type. The tensile speed was 500 mm / min. (3) 100% elongation stress: According to JIS K 6301, a test piece was prepared by punching a 1 mm thick press sheet into a No. 3 dumbbell mold. The tensile speed was 500 mm / min. (4) Elongation at break: Based on JIS K 6301, a test piece was prepared by punching a 1 mm thick press sheet into a No. 3 dumbbell type. The tensile speed was 500 mm / min. (5) Compression set: Based on JIS K6262,
The test piece used was a 6.3 mm-thick press sheet. 25
Under conditions of% deformation, 70 ° C x 22 hours and 70 ° C x 50
It was measured at 0 hours. (6) Volume change rate: According to JIS K 6301, a test piece was prepared by punching a 1 mm thick pressed sheet into a No. 3 dumbbell type. Using IRM # 902 oil, 70 ° C x
The change in weight for 22 hours was measured. (7) Bleed resistance: The molded product obtained by compressing the molded product by 25% in an environment of 70 ° C. for 168 hours is visually observed for bleeding and blooming of a low molecular weight material, and evaluated according to the following criteria. did. Good: Good Δ: Somewhat bad ×: Bad (8) Tack resistance: The test piece was obtained by stacking two 1 mm-thick press sheets and leaving them to stand at a load of 500 g / cm ² for 24 hours. Was visually observed and evaluated according to the following criteria. ：: good Δ: somewhat bad ×: bad (9) Injection moldability: A 130 mm × 130 mm × 2 mm sheet was injection molded, its appearance was visually observed, and the presence or absence of flow marks and sink marks was evaluated according to the following criteria. did. ○: good Δ: somewhat bad ×: bad

The components used in the examples and comparative examples are as follows. (1) Hydrogenated block copolymer component (a): Septon 4
077 (trademark; manufactured by Kuraray Co., Ltd.), styrene content 3
0% by weight, isoprene content 70% by weight, number average molecular weight 260,000, weight average molecular weight 320,000, molecular weight distribution 1.23, hydrogenation rate 90% or more. (2) Polybutene component (b): HV-100 ( (Trademark; manufactured by Nippon Petrochemical Co., Ltd.), number average molecular weight 980 (3) Propylene block copolymer component (c): PP-
BC8 (trademark; manufactured by Nippon Polychem Co., Ltd.), crystallinity;
Tm166 ° C, ΔHm82mJ / mg, MFR1.8g
/ 10 min (4) Liquid polybutadiene component (d): R-45HT
(Trademark; manufactured by Idemitsu Petrochemical Co., Ltd.), having a hydroxyl group (acrylic primary) and a copolymerizable unsaturated double bond (1,4 bond 80%) as a functional group, number average molecular weight 2800 (5) Organic Peroxide component (e): Perhexa 25B (trademark; manufactured by NOF CORPORATION) (6) Silicone oil component (f): SH200 (trademark; manufactured by Toray Dow Corning Silicone Co., Ltd.), viscosity 100
0cSt (7) Crosslinking aid component (g): NK ester 3G (trademark)
(8) SBS block copolymer component (h): VECTO
R2518 (trademark; manufactured by DEXCO) (9) Ethylene-butene copolymer rubber component (i): Esprene N0441 (manufactured by Sumitomo Chemical Co., Ltd.) (10) Calcium carbonate component (j): NS400 (trademark; Sankyo Seimitsu Co., Ltd.) (11) Hindered phenol / phosphite / lactone complex antioxidant component (k): HP2215 (trademark; manufactured by Ciba Specialty Chemicals)

Examples 1 to 6 and Comparative Examples 1 to 8 The components shown in Tables 1 and 2 were used and charged into a twin-screw extruder having an L / D of 47. Melt kneading was performed at several 350 rpm to form pellets. Next, the obtained pellets were injection molded to prepare test pieces, which were subjected to the respective tests. The evaluation results are shown in Tables 1 and 2.

[0060]

[Table 1]

[0061]

[Table 2]

As is clear from Tables 1 and 2, Examples 1 to 6 are the thermoplastic elastomer compositions of the present invention. Regardless of the presence or absence of optional components (f) to (k), any of the thermoplastic elastomer compositions showed good properties.

On the other hand, in Comparative Examples 1 and 2, the compounding amount of the component (b) was out of the range of the present invention. When the amount of the component (b) is small, the hardness of the composition becomes too high, the flexibility is lost, and a product having a rubbery feeling cannot be obtained, and the injection moldability is impaired. became. In Comparative Examples 3 and 4, the amount of the component (c) was out of the range of the present invention. When the amount of the component (c) is small, the injection moldability deteriorates. When the amount of the component (c) is large, the flexibility is lost and the rubber elasticity is deteriorated. In Comparative Examples 5 and 6, the compounding amount of the component (d) was out of the range of the present invention. When the amount of the component (d) is small, the holding power of the softener is reduced, and tackiness and bleeding become remarkable.
As a result, the injection moldability deteriorated. Comparative Examples 7 and 8
Is such that the amount of component (e) is outside the scope of the present invention. When the component (e) is small, bleeding becomes remarkable,
If the amount of the component (e) is too large, the injection moldability is deteriorated.

[0064]

Industrial Applicability The thermoplastic elastomer composition of the present invention suppresses bleed-out of a softener, is excellent in flexibility and compression set, and causes a molded article from the composition of the present invention to cause environmental pollution. In particular, when used for an elastic member or the like of an ink jet recording apparatus, the ink does not deteriorate, and when used for a bottle cap packing elastic member or the like, the contents of the bottle do not deteriorate, and a polyolefin or hard thermoplastic elastomer is used. When used for a multicolor molded seal member or the like, it is possible to obtain an excellent part free from bleeding.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08L 9/00 C08L 9/00 23/20 23/20 (72) Inventor Maari Yamamoto Nihonbashi, Chuo-ku, Tokyo 3-11-5 Honcho RIKEN Vinyl Industrial Co., Ltd. F-term (reference) 3E084 HC03 HC10 4F070 AA06 AA12 AA17 AB01 AB08 AB09 AB11 AB12 AC56 AC75 AC92 AE02 AE08 FA03 FA17 FB06 4J002 AC05Y AE05W BB124 BB144 BB154 BP17W0CP01 EK036 EK046 EK056 EK066 EK086 EU187 FD010 FD02W FD070 FD146 FD155 FD157 GG01 GJ02 GM00 GN00 GP00 4J026 HA06 HA14 HA15 HA16 HA20 HA26 HA27 HA32 HA39 HB16 HB26 HB27 HB32 HB39 HCB HC HC HC HC HC HC HC HC HC HC HC HC HC HC

Claims (6)

[Claims] 1. A hydrogenated block copolymer comprising (a) at least two polymer blocks A mainly composed of an aromatic vinyl compound and at least one polymer block B mainly composed of isoprene. (B) 50-250 parts by weight of a softening agent for non-aromatic rubber, (c) 2-80 parts by weight of a peroxide decomposable olefin resin, (d) liquid 0.1 to 125 parts by weight of polybutadiene and (e) organic peroxide
A thermoplastic elastomer composition obtained by melt-kneading a composition containing from 0.01 to 1.25 parts by weight. 2. The hydrogenated block copolymer (a) is such that 70 to 100% by weight of isoprene in the polymer block B is 1,1.
Having a 4-microstructure, wherein at least 90% of the isoprene-based double bonds are hydrogenated, the polymer block A is 5 to 70% by weight of the entire component (a), and The weight average molecular weight of the whole united is 50,0
2. The weight ratio is from 00 to 550,000.
The thermoplastic elastomer composition as described in the above. 3. The thermoplastic elastomer composition according to claim 1, wherein (b) the softener for non-aromatic rubber is polybutene. 4. The thermoplastic elastomer composition according to claim 1, further comprising (f) 0.1 to 50 parts by weight of a silicone oil. 5. (g) Ester cross-linking assistant 0.1 to 50
The thermoplastic elastomer composition according to any one of claims 1 to 4, further comprising parts by weight. 6. An elastic member for a bottle cap packing and an elastic member for an ink jet recording apparatus, comprising the thermoplastic elastomer composition according to any one of claims 1 to 5.