JPH0692521B2 - Elastomer composition having thermoplasticity - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION << Industrial Field of Application >> The present invention relates to a hydrogenated block copolymer or its modified product and α, β.
-A novel thermoplastic elastomer composition comprising an unsaturated nitrile-conjugated diene copolymer and / or a hydrogenated product thereof, which is excellent in mechanical properties and is excellent in rubber elasticity, weather resistance, heat resistance and oil resistance Is.

<< Prior Art and Problems >> Thermoplastic elastomers are used as rubbers that do not require vulcanization in the fields of automobile parts, household appliances, footwear, electric wire coatings, sundries, etc. in recent years.

Of these, styrene-based thermoplastic elastomers such as styrene-butadiene block copolymers, styrene-isoprene block copolymers and hydrogenated products of these block copolymers are highly flexible and have good rubber elasticity at room temperature. Therefore, it is widely used in compounds such as adhesives / sealants and thermoplastic resins.

However, this styrene-based thermoplastic elastomer has rubber properties due to physical cross-linking due to aggregation of the styrene phase, and flow occurs at a temperature exceeding the glass transition point of styrene (about 100 ° C). Generally, it was difficult to use in an environment exceeding that temperature.

Further, this styrene-based thermoplastic elastomer is generally inferior in resistance to hydrocarbon solvents such as oil and gasoline, as is clear from the fact that it is generally synthesized by solution polymerization in a hydrocarbon solvent. It was

As a method for improving these, a method of mixing a thermoplastic resin having excellent heat resistance and oil resistance with a styrene-based thermoplastic elastomer (JP-A-58-7443, JP-A-59-27942, JP-A-59-27942). No. 27943), a method of mixing and co-vulcanizing a vulcanizable rubber (such as Japanese Patent Laid-Open No. 61-60739) has been proposed. According to these, heat resistance and oil resistance are improved. However, there is still room for improvement, and there is a drawback that the good rubber elasticity and processability originally possessed by the styrene-based thermoplastic elastomer are impaired.

On the other hand, nitrile rubber is a rubber that has excellent heat resistance and oil resistance, but nitrile rubber can be used as a rubber for other rubbers (for example, EPM, EPDM, E
VA) and vulcanized to add the properties of nitrile rubber to other rubbers, such as heat resistance and oil resistance (JP-A-58-40332, JP-A-60-112839, JP-A-60-112839). 61-40342
JP-A-61-283639, etc.) are also proposed, but these are indispensable to be vulcanized, and since they are the first compositions to produce rubber elasticity by vulcanization, their thermoplasticity is completely lost. There are known drawbacks.

A composition comprising a styrene thermoplastic elastomer and an α, β-unsaturated nitrile-containing polymer (JP-A-53-124559,
JP-A-53-138453, etc.) has also been proposed, but the α, β-unsaturated nitrile-containing polymer contained in this composition is a resinous polymer, and this composition does not have rubber elasticity. It is a resin.

Further, a thermoplastic elastomer composition comprising a copolymer of a styrene-based thermoplastic elastomer and a conjugated diene and acrylonitrile (JP-A-48-80643) has also been proposed, but the thermoplastic elastomer contained in this composition is Due to the presence of unsaturated double bonds in the polybutadiene chain,
It has the drawback that sufficient weather resistance cannot be expected. Further, the conjugated diene-nitrile copolymer contained in this composition is a resinous copolymer having crystallinity, and in this composition, the flexibility of the styrene-based thermoplastic elastomer, good rubber elasticity, etc. are sacrificed to some extent. become.

<< Means for Solving the Problem >> The present inventors have earnestly studied to obtain a thermoplastic composition in which the heat resistance and oil resistance of the styrene-based thermoplastic elastomer are improved, and as a result, nitrile was added to the styrene-based thermoplastic elastomer. The present inventors have found that a uniform thermoplastic composition can be obtained by adding rubber or a hydrogenated product thereof, and arrived at the present invention.

The present invention, by blending a styrene-based thermoplastic elastomer, especially a hydrogenated block copolymer or modified product thereof, an α, β-unsaturated nitrile-conjugated diene-based copolymer rubber and / or a hydrogenated product thereof, This is a solution to the above problems.

That is, the present invention hydrogenates a block copolymer comprising at least one vinyl aromatic compound-based polymer block A and at least one conjugated diene compound-based polymer block B. The hydrogenated block copolymer and / or the modified hydrogenated block copolymer modified product (I) containing a carboxylic acid group or a derivative group thereof,
It contains an α, β-unsaturated nitrile-conjugated diene-based copolymer rubber and / or its hydrogenated product (II), and has (I) / (I
The weight ratio of (I) is 95/5 to 50/50, and at least (II) is cross-linked, which has excellent mechanical properties and rubber elasticity, weather resistance, and heat resistance. The present invention provides a novel thermoplastic elastomer composition having excellent oil resistance.

Hereinafter, the present invention will be described in detail.

The hydrogenated block copolymer that can be used as one of the components (I) includes a polymer block A mainly containing at least one vinyl aromatic compound and a polymer block mainly containing at least one conjugated diene compound. It is obtained by hydrogenating a block copolymer having a structure consisting of a united block B, and is, for example, AB, ABA, BAB-
A, (AB) _n X (n = 2 to 4, X is a coupling agent residue), (B-A-B) _n X (n = 2 to 4, X is a coupling agent residue) and these It is a hydrogenated block copolymer of a mixture that is hydrogenated. The hydrogenated block copolymer contains a vinyl aromatic compound in an amount of 5 to 95% by weight, preferably
Contains 10 to 60% by weight. More preferably, at 15 to 45% by weight, such a hydrogenated block copolymer exhibits excellent properties as a thermoplastic elastomer. Further referring to the block structure, the polymer block A mainly containing a vinyl aromatic compound is a vinyl aromatic compound polymer block or a vinyl aromatic compound containing more than 50% by weight, preferably 70% by weight or more. It has a structure of a copolymer block of an aromatic compound and a hydrogenated conjugated diene compound, and further, a polymer block B mainly composed of a hydrogenated conjugated diene compound is a hydrogenated conjugated block. Diene compound polymer block or hydrogenated conjugated diene compound is more than 50% by weight, preferably 70%
It has a structure of a copolymer block of a hydrogenated conjugated diene compound and a vinyl aromatic compound which are contained in an amount of at least wt%. Further, the polymer block A mainly composed of these vinyl aromatic compounds and the polymer block B mainly composed of the hydrogenated conjugated diene compound are the hydrogenated conjugated diene in the molecular chain of each polymer block. Distribution of compound or vinyl aromatic compound is random,
It may be tapered (in which the monomer distribution increases or decreases along the molecular chain), partially block-like or any combination thereof, and the polymer block A mainly composed of the vinyl aromatic compound is hydrogenated. When there are two or more polymer blocks B each containing the conjugated diene compound as a main component, the respective blocks may have the same structure or different structures.

Examples of the vinyl aromatic compound constituting the hydrogenated block copolymer include styrene, α-methylstyrene, 4-methylstyrene, vinyltoluene, 4-tert-butylstyrene, and 1,1′-diphenylethylene. 1 type or 2 types or more can be selected from the above, and styrene is preferable among them. Further, as the conjugated diene compound before hydrogenation constituting the hydrogenated conjugated diene compound, for example, butadiene, isoprene, 1,3-pentadiene, 2,3-dimethyl-
One or more kinds can be selected from 1,3-butadiene, 1,3-hexadiene and the like, and among them, butadiene, isoprene and a combination thereof are preferable. The polymer block B mainly composed of the conjugated diene compound before hydrogenation can have any microstructure in the block, but in order to have good rubber elasticity, for example, polybutadiene block is used. In, the 1,2-vinyl bond content is 10 to 80%, preferably 25 to 45%.

The number average molecular weight of the hydrogenated block copolymer is 5,000 to 1,0.
00,000, preferably 10,000 to 800,000, from the viewpoint of maintaining the balance between physical properties and processability of the composition of the present invention, 30,000 to 300,000 is a more preferable range, and molecular weight distribution (weight average molecular weight (Mw) and number) The ratio (Mw / Mn) to the average molecular weight (Mn)] is 10 or less. Furthermore, the molecular structure of the hydrogenated block copolymer is
It may be linear, branched, radial or any combination thereof.

The hydrogenated block copolymer may be produced by any method as long as it has the above-mentioned structure. For example, Japanese Patent Publication No. 40-2379
According to the method described in JP-B-8, a vinyl aromatic compound-conjugated diene compound block copolymer is synthesized in an inert solvent using a lithium catalyst or the like, and then, for example, JP-B-42-8704 or JP-B-K-72704. According to the method described in JP-A-43-6636, particularly preferably JP-B-63-4841 and the method described in JP-B-63-5401, hydrogen in the presence of a hydrogenation catalyst in an inert solvent is used. The hydrogenated block copolymer used in the present invention can be synthesized by adding it. At that time, at least 80% of the aliphatic double bond based on the conjugated diene compound of the vinyl aromatic compound-conjugated diene compound block copolymer is hydrogenated, and a polymer block mainly composed of the conjugated diene compound is morphologically olefined. The polymer compound B is converted into a polymerizable compound. Further, a hydrogen of an aromatic double bond based on a vinyl aromatic compound copolymerized with a polymer block A mainly containing a vinyl aromatic compound and, if necessary, a polymer block B mainly containing a conjugated diene compound. There is no particular limitation on the addition rate, but the hydrogen addition rate
It is preferably 20% or less.

The amount of unhydrogenated aliphatic double bonds contained in the hydrogenated block copolymer can be easily known by an infrared spectrophotometer, a nuclear magnetic resonance apparatus or the like.

On the other hand, a modified hydrogenated block copolymer that can be used as another component (I) is a product obtained by binding the above-mentioned hydrogenated block copolymer with a molecular unit containing a carboxylic acid group or a derivative group thereof. Is. Such a hydrogenated block copolymer modified product is obtained by adding an unsaturated carboxylic acid or a derivative thereof to the above hydrogenated block copolymer in a solution state or a molten state, preferably using a radical initiator. Can be obtained. As the hydrogenated block copolymer that can be used for such addition modification, any of those defined above can be used, and as an example of the unsaturated carboxylic acid or its derivative to be added to the hydrogenated block copolymer. Is maleic acid, halogenated maleic acid, itaconic acid,
Fumaric acid, citraconic acid, cis-4-cyclohexene-
1,2-dicarboxylic acid, endo-cis-dicyclo- [2,2,
1] -5-heptene-2,3-dicarboxylic acid and the like and anhydrides of these dicarboxylic acids, esters, amides, imides and the like, and
Acrylic acid, methacrylic acid, crotonic acid, isocrotonic acid, mesaconic acid, anseric acid, etc. and esters of these monocarboxylic acids, for example, methyl methacrylate, glycidyl methacrylate and amides, ethers, nitriles, and derivatives of thiol, etc. Of these, maleic anhydride or glycidyl methacrylate is particularly preferable.

The method for producing these hydrogenated block copolymer modified products is not particularly limited in the present invention, but the obtained hydrogenated block copolymer modified product contains an unfavorable component such as gel, and its melt viscosity. Is significantly increased and workability deteriorates, which is not preferable. A preferred method is, for example, in an extruder in the presence of a radical initiator,
There is a method of reacting a hydrogenated block copolymer with an unsaturated carboxylic acid or its derivative.

The addition amount of the unsaturated carboxylic acid or its derivative to the hydrogenated block copolymer is preferably 20 parts by weight or less, more preferably 10 parts by weight or less per 100 parts by weight of the hydrogenated block copolymer. Even if the addition amount exceeds 20 parts by weight, the modification effect is not increased as compared with the addition amount less than 20 parts by weight. The unsaturated carboxylic acid or derivative thereof used in the present invention can be used not only in one kind but also in a mixture of two or more kinds.

Α which can be used as the component (II) in the composition of the present invention,
β-unsaturated nitrile-conjugated diene copolymer rubber and /
Alternatively, the hydrogenated product thereof has an α, β-unsaturated nitrile / conjugated diene weight ratio of 10/90 to 80/20, preferably 15/8.
Those having a molecular weight of 5 to 50/50 and a molecular weight of 5,000 to 200,000 and / or hydrogenated products thereof are preferred.

Specific examples of the α, β-unsaturated nitrile constituting the α, β-unsaturated nitrile-conjugated diene-based copolymer rubber include acrylonitrile, methacrylonitrile, α-chloroacrylonitrile, α-fluoroacrylonitrile,
Examples thereof include ethacrylonitrile, and of these, acrylonitrile is particularly preferable.

Further, as the conjugated diene compound which is the other constituent component of the α, β-unsaturated nitrile-conjugated diene copolymer rubber, for example, butadiene, isoprene, 1,3-pentadiene, 2,3-dimethyl-1 One or more of 1,3-butadiene and 1,3-hexadiene can be selected, and butadiene is preferred.

Further, the portion based on the conjugated diene compound in the α, β-unsaturated nitrile-conjugated diene copolymer rubber may be completely or partially hydrogenated. In the present invention, the α, β-unsaturated nitrile-conjugated diene copolymer rubber or its hydrogenated product may be used alone,
Although it may be used as a mixture, a hydrogenated product is particularly preferably used from the viewpoint that the weather resistance of the hydrogenated block copolymer is not impaired.

The α, β-unsaturated nitrile-conjugated diene-based copolymer rubber can be produced, for example, by emulsion polymerization using an ordinary radical polymerization catalyst. Further, hydrogenated products of the copolymer are disclosed in, for example, JP-A-45-39275 and JP-A-50.
It can be obtained by hydrogenating the conjugated diene compound unit portion in the copolymer according to the method described in JP-A-71681.

In the composition of the present invention, such component (I) and (II)
The ratio of the components is such that the weight ratio of (I) / (II) is 95/5 to 50/50.
Is. When the proportion of (II) in (I) + (II) is less than 5% by weight, the composition does not exhibit sufficient heat resistance and oil resistance,
Further, if it exceeds 50% by weight, when the composition is cross-linked, the processability is deteriorated and good thermoplasticity is not exhibited, which is not preferable.

In the composition of the present invention, α, β-unsaturated nitrile-
Crosslinking agent for conjugated diene copolymer rubber, for example, a crosslinking agent such as an organic peroxide, a crosslinking agent such as an allyl compound, sulfur and oximes, a crosslinking accelerator such as zinc oxide and magnesium oxide, and the like are blended. You can also do it. The amount of such a cross-linking agent, etc. is not particularly limited, but is a degree that does not impair the thermoplasticity of the present composition, that is, the optimum amount for crosslinking the α, β-unsaturated nitrile-conjugated diene copolymer rubber 70-100% of the amount
Is preferred.

The composition of the present invention may be blended with a thermoplastic resin such as polyethylene or polypropylene, a filler such as calcium carbonate, carbon black, silica or the like, an oil or the like, if necessary.

Means used for mixing the compositions of the present invention include chemical mixing methods such as solution blending and mechanical mixing methods, such as rolls, extruders, Brabender, etc., but are not of course limited to these. Absent. For uniform mixing, it is preferable to select conditions of 160 ° C. or higher.

Further, when the component (II) is cross-linked, the method is not particularly limited, but the hydrogenated block copolymer and the α, β-unsaturated nitrile-conjugated diene-based copolymer rubber may be mixed with or at the same time. After that, a method of adding a crosslinking agent or the like as the component (II) to crosslink is preferable from the viewpoint of obtaining a crosslinked composition with good mixing.

<Effects of the Invention> According to the present invention, a novel thermoplastic elastomer composition having both excellent mechanical properties, rubber elasticity, and weather resistance of a hydrogenated block copolymer and excellent heat resistance and oil resistance of nitrile rubber. The product can be obtained and can be very suitably used for various hoses requiring oil resistance and heat resistance, various roll molded products, and the like, for example, automobile parts, electric parts, various industrial parts and the like.

<< Examples >> Hereinafter, the present invention will be described more specifically with reference to Examples.
The present invention is not limited to these examples as long as the gist thereof is not exceeded.

Reference Example 1 Synthesis of Hydrogenated Block Copolymer (1-1) Polystyrene-hydrogenated polybutadiene-polystyrene structure by the method described in JP-B-63-4841 and bound styrene content of 30%, A hydrogenated block copolymer having a 1,2-vinyl bond content of 35% in the polybutadiene portion before hydrogenation, a number average molecular weight of 150,000, a molecular weight distribution of 1.04 and a hydrogenation rate of 100% in the polybutadiene portion was synthesized. (1
-2) having a structure of polystyrene-hydrogenated polyisoprene-polystyrene in the same manner as (1-1),
30% of bound styrene, polyisoprene part before hydrogenation
A hydrogenated block copolymer having a 3,4-vinyl bond content of 33%, a number average molecular weight of 120,000, a molecular weight distribution of 1.04, and a hydrogenation rate of 99% in the polyisoprene part was synthesized.

(1-3) In the same manner as (1-1), it has a structure of hydrogenated polybutadiene-polystyrene-hydrogenated polybutadiene-polystyrene and has a bound styrene content of 30.
%, 1,2-vinyl bond content of the polybutadiene portion before hydrogenation was 35%, number average distribution amount was 50,000, molecular weight distribution was 1.04, and hydrogenation rate of the polybutadiene portion was 99%.

(1-4) In the same manner as (1-1), (polystyrene-
Has a hydrogenated polybutadiene) ₄ Si structure, bound styrene content 30%, 1 polybutadiene portion before hydrogenation,
A hydrogenated block copolymer having a 2-vinyl bond content of 35%, a number average molecular weight of 70,000, a molecular weight distribution of 1.04 and a hydrogenation rate of 96% in the polybutadiene part was synthesized.

Reference Example 2 Synthesis of modified hydrogenated block copolymer (2-1) Hydrogenated block copolymer obtained in (1-1)
1 part by weight of maleic anhydride and 0.1 part by weight of 2,5-dimethyl-2,5-di (tertiary butylperoxy) hexane were mixed per 100 parts by weight, and a twin screw extruder with a diameter of 50 mm was set at 250 ° C. The addition modification reaction was carried out. The modified hydrogenated block copolymer obtained was one in which 0.75 parts by weight of maleic anhydride was added.

(2-2) Hydrogenated block copolymer obtained in (1-3)
1 part by weight of maleic anhydride and 0.1 part by weight of 2,5-dimethyl-2,5-di (tertiary butylperoxy) hexane were mixed per 100 parts by weight, and a twin screw extruder with a diameter of 50 mm was set at 250 ° C. The addition modification reaction was carried out. The modified hydrogenated block copolymer obtained was one in which 0.55 parts by weight of maleic anhydride was added.

(2-3) Hydrogenated block copolymer obtained in (1-3)
2.5 parts by weight of glycidyl methacrylate per 100 parts by weight,
Mix 0.5 parts by weight of di-tert-butyl peroxide,
The denaturation reaction was carried out with a 45 mmφ vented twin-screw extruder set to ℃ while performing forced venting (pressure reduction degree: 750 mmHgG) using a vacuum pump. The modified hydrogenated block copolymer obtained was one in which 1.5 parts by weight of glycidyl methacrylate was added.

Examples 1 to 39 and Comparative Examples 1 to 27 Thermoplastic elastomer compositions having the compounding ratios shown in Tables 1 to 8 were prepared by rolls at 180 ° C., and formed into sheets having a thickness of about 2 mm.
After compression molding at 180 ° C., it was subjected to the following test.

Heat resistance: According to JIS K6301 "Physical test method for vulcanized rubber", the above compression-molded sheet (hereinafter referred to as press sheet) is punched out into a dumbbell-shaped type 3 test piece at 25 ° C, 70
Tensile strength at 25 ℃ was measured at 70 ℃, 70% or more, and 50% at 100 ℃.
Those retained above were evaluated as ◯, and those less than that value were evaluated as x.

Oil resistance: In accordance with JIS K6301 "Physical test method for vulcanized rubber", the above press sheet was punched out into dumbbell-shaped No. 3 type test piece, and immersed in JIS No. 3 oil at 70 ° C for 1 hour, then taken out and immersed. The case where the surface did not change before and after and the weight change before and after the immersion was 20% or less was evaluated as ◯, and the case where the surface changed or the weight change exceeded this value was evaluated as x.

Weather resistance: In accordance with JIS K1415 "Method of accelerated exposure test for plastic building materials", the above press sheet is punched into a dynebell type No. 3 test piece with a black panel temperature of 63 ° C and a spray cycle of 12 minutes / 60 minutes After 500 hours of exposure in a shear weather meter, it was taken out and the tensile strength retention before and after exposure was 95% or more, and the surface condition did not change before and after exposure. ○, retention rate below this value Alternatively, the change in surface condition was evaluated as x.

Thermoplastic: Melt flow rate (MFR) of each thermoplastic elastomer composition according to JIS K7210 "Method of flow test for thermoplastic plastics" is set to condition 14 (test temperature 230 ° C, test load 2.16kg).
It was measured in f), and those with MFR of 0.1 or more were evaluated as ◯, and those below this value were evaluated as x.

1) to 12) in Tables 1 to 8 are as follows.

1): Elastomer synthesized in Reference Example, and K manufactured by Shell
raton G1652 2): Hydrogenated nitrile rubber (A) = Bayer Therban 1707 Hydrogenated nitrile rubber (B) = Nippon Zeon Zetpol 2010 Nitrile rubber = Nippon Zeon Nipol 1042 3): Asahi Kasei Polypro E-1100 4): PW380 manufactured by Idemitsu Kosan 5): Triallyl isocyanurate 6): Peroximon F40 manufactured by NOF Corporation 7): Dioctyl sebacate (DOS) 8): Trimethylol tris- (β-thiopropionate) ) 9): Tetramethylthiuram disulfide (TMTD) 10): Tetraethylthiuram disulfide (TETD) 11): 2-mercaptobenzothiazole (MBT) 12): Hexamethylenetetramine (H)

Claims (2)

[Claims] 1. A block copolymer obtained by hydrogenating a polymer block A containing at least one vinyl aromatic compound as a main component and a polymer block B containing at least one conjugated diene compound as a main component. The hydrogenated block copolymer and / or the hydrogenated block copolymer modified product (I) containing a carboxylic acid group or a derivative group thereof, and an α, β-unsaturated nitrile-conjugated diene-based copolymer rubber and Or or its hydrogenated product (II) as an essential component, and (I) / (II)
The thermoplastic elastomer composition having a weight ratio of 95/5 to 50/50. 2. The thermoplastic elastomer composition according to claim 1, which is obtained by crosslinking at least (II).