JPH0692520B2 - Thermoplastic elastomer composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a hydrogenated block copolymer or a modified product thereof and α, β.
-Unsaturated nitrile-conjugated diene copolymer and / or its hydrogenated product, and a novel thermoplastic elastomer having excellent mechanical properties and excellent rubber elasticity, weather resistance, heat resistance, and oil resistance, which is made of fluororubber It relates to a composition.

[Conventional technology and problems]

BACKGROUND ART In recent years, thermoplastic elastomers have been used as rubbers that do not require vulcanization in fields such as automobile parts, home electric appliance parts, footwear, electric wire coatings, and sundries.

Of these, stainless steel thermoplastic elastomers such as styrene-butadiene block copolymers and 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 as a compound with 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 fluidization occurs at a temperature exceeding the glass transition point (about 100 ° C.) of styrene. It was difficult to use in an environment exceeding that temperature.

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

As a method for improving these, a method in which a thermoplastic resin having excellent heat resistance and oil resistance is mixed with a styrene-based thermoplastic elastomer (JP-A-58-7443, JP-A-59-27942, and 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, there are fluororubbers that are extremely excellent in heat resistance and oil resistance, but by mixing the fluororubber with other rubbers (eg NBR, acrylic rubber) and vulcanizing it, the characteristics of the fluororubber can be added to other rubbers. That is, a method of adding heat resistance and oil resistance (JP-A-60-141737, 62-225227, 62-51439, 62-1).
No. 56144, etc.) have also been proposed, but these are indispensable to be vulcanized, and since they are compositions that cause rubber elasticity only after vulcanization, they have a drawback that thermoplasticity is completely lost.

On the other hand, a method in which a fluororesin and a fluororubber are mixed and partially crosslinked to obtain a thermoplastic elastomer (Japanese Patent Laid-Open No. Sho 61-61).
However, the composition obtained by this method has many drawbacks in industrial use, such as not only the processing temperature is restricted at a flow temperature of 300 ° C. or higher but also the good thermoplasticity. have.

Further, generally, the styrene-based thermoplastic elastomer and the fluororubber are hardly compatible with each other simply by mixing them, and it is not yet known to uniformly mix them.

[Means for Solving the Problems]

In order to obtain a thermoplastic composition in which the styrene-based thermoplastic elastomer and the fluororubber are uniformly mixed and the characteristics of the fluororubber are added to the styrene-based thermoplastic elastomer, the heat resistance and the oil resistance are remarkably improved. As a result of diligent studies, it was surprisingly found that a uniform thermoplastic composition can be obtained by adding a nitrile rubber or its hydrogenated compound to a poorly miscible styrene-based thermoplastic elastomer and fluororubber, and the present invention Arrived

The present invention provides a styrene-based thermoplastic elastomer, particularly a hydrogenated block copolymer, by blending an α, β-unsaturated nitrile-conjugated diene copolymer and / or a hydrogenated product thereof, and a fluororubber, It is a solution to the problem.

That is, the present invention hydrogenates a block copolymer consisting of at least one polymer block A containing a vinyl aromatic compound as a main component and at least one polymer block B containing a conjugated diene compound as a main component. The hydrogenated block copolymer and / or the modified product of the hydrogenated block copolymer containing a carboxylic acid group or a derivative group thereof, and
α, β-unsaturated nitrile-conjugated diene copolymer and /
Alternatively, the hydrogenated product (II) and a fluororubber (III) are contained, and the weight ratio of (I) / [(II) + (III)] is 95/5 to 5
0/50, and at least (II) and / or (II
The present invention provides a novel thermoplastic elastomer composition which is characterized by being formed by crosslinking I) and which has excellent mechanical properties and excellent rubber elasticity, weather resistance, heat resistance, and 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 containing at least one vinyl aromatic compound as a main component and a polymer block containing at least one conjugated diene compound as a main component. It is obtained by hydrogenating a block copolymer having a structure composed of a united block B, and is, for example, AB, ABA, BAABA, (A-
BnX (n = 2 to 4, X is a coupling agent residue, (BA
-BnX (n = 2 to 4, X is a coupling agent residue) and hydrogenated hydrogenated block copolymers of these mixtures. The hydrogenated block copolymer contains a vinyl aromatic compound in an amount of 5 to 95% by weight, preferably 10 to 60% by weight.
More preferably, at 15 to 45% by weight, the hydrogenated block copolymer exhibits excellent properties as a thermoplastic elastomer. Further referring to the block structure, the polymer block A mainly comprising a vinyl aromatic compound is a vinyl aromatic compound polymer block or a vinyl aromatic compound-containing vinyl block containing more than 50% by weight, preferably 70% by weight or more. Has a structure of a copolymer block of an aromatic compound and a hydrogenated conjugated diene compound, and further,
The polymer block B mainly composed of a hydrogenated conjugated diene compound contains more than 50% by weight, preferably 70% by weight or more of a hydrogenated conjugated diene compound polymer block or a hydrogenated conjugated diene compound. It has a structure of a copolymer block of a hydrogenated conjugated diene compound and a vinyl aromatic compound. Further, the polymer block A mainly composed of these vinyl aromatic compounds and the polymer block B mainly composed of hydrogenated conjugated diene compound are the hydrogenated conjugated diene in the molecular chain of each polymer block. The distribution of the compound or the vinyl aromatic compound may be random, tapered (in which the monomer distribution increases or decreases along the molecular chain), partially block-shaped, or any combination thereof. When there are two or more heavy block A mainly composed of and polymer block B mainly composed of hydrogenated conjugated diene compound, each block may have the same structure or different structures. Good.

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 or 2
One or more kinds can be selected, and styrene is preferable. Also,
Examples of the conjugated diene compound before hydrogenation constituting the hydrogenated conjugated diene compound include, for example, butadiene, isoprene, 1,3-pentadiene, and 2,3-dimethyl-1,3-
One kind or two or more kinds can be selected from butadiene 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 hydrogenated block copolymer has a number average molecular weight of 5,000 to 1,0.
00,000, preferably 10,000 to 800,000, from the viewpoint of maintaining the balance between the physical properties and processability of the composition of the present invention.
A more preferable range is 30,000 to 300,000, and the molecular weight distribution [ratio of weight average molecular weight (Mw) to number average molecular weight (Mn) (Mw / Mn)] is 10 or less. Further, the molecular structure of the hydrogenated block copolymer 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, JP-B-Koku In the presence of a hydrogenation catalyst in an inert solvent, the method described in JP-A-43-6636, particularly preferably the method described in JP-B-59-133203 and JP-A-60-79005. The hydrogenated block copolymer used in the present invention can be synthesized by hydrogenation.
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 the polymer block mainly composed of the conjugated diene compound is morphologically modified with olefin. The polymer compound block B is converted. Further, 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 a polymer block B mainly containing a conjugated diene compound, if necessary. The addition rate is not particularly limited, but the hydrogen addition rate 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, the 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 hydrogenated block copolymer to which a molecular unit containing a carboxylic acid group or its derivative group is bonded. Is. Such hydrogenated block copolymer modified product is obtained by adding an unsaturated carboxylic acid or a derivative thereof to the hydrogenated block copolymer in a solution state or a molten state, preferably using a radical initiator. To be 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,
Cis-4-cyclohexene-1,2-dicarboxylic acid, endo-cis-bicyclo- [2,2,1] -5-heptene-2,3-
Dicarboxylic acids and the like, anhydrides of these dicarboxylic acids, esters, amides, imides and the like, and acrylic acid, methacrylic acid, crotonic acid and the like and esters of these monocarboxylic acids,
Examples thereof include derivatives such as methyl methacrylate, glycidyl methacrylate and amide, and among these, maleic anhydride and glycidyl methacrylate are 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 its derivative 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,
The β-unsaturated nitrile-conjugated diene copolymer and / or its hydrogenated product are the components (I) and (II) according to the present invention.
In addition to acting as a compatibilizer for component I), it is an essential component in terms of balancing the physical properties such as oil resistance and heat resistance of the resulting composition and processability. As the component (II), a weight ratio of α, β-unsaturated nitrile / conjugated diene is 10/90 to 80/20, preferably 15/85 to 50/50 and a molecular weight of 5,
Those of 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 copolymer include:
Examples thereof include acrylonitrile, methacrylonitrile, α-chloroacrylonitrile, α-fluoroacrylonitrile and ethacrylonitrile, and among 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-based copolymer, for example, butadiene, isoprene, 1,3-pentadiene, 2,3-dimethyl-1, One or two or more kinds can be selected from 3-butadiene and the like, and among them, butadiene is preferable.

Further, the part based on the conjugated diene compound in the α, β-unsaturated nitrile-conjugated diene-based copolymer may be completely or partially hydrogenated. In the present invention,
The α, β-unsaturated nitrile-conjugated diene-based copolymer or its hydrogenated product may be used alone or as a mixture, but the (I) component and the (III) component are well mixed. From the viewpoint of solubilization and not impairing the weather resistance of the hydrogenated block copolymer, it is particularly preferable to use a hydrogenated substance.

The α, β-unsaturated nitrile-conjugated diene-based copolymer is
For example, it can be produced by emulsion polymerization using an ordinary radical polymerization catalyst. Further, hydrogenated products of the copolymer are, for example, disclosed in JP-A-45-39275 and JP-A-50-716.
It can be obtained by hydrogenating the conjugated diene compound unit portion in the copolymer by the method described in Japanese Patent Publication No. 81 etc.

On the other hand, examples of the fluororubber that can be used as the component (III) of the composition according to the present invention include, for example, tetrafluoroethylene-
One kind or two or more kinds can be selected from propylene hexafluoride-vinylidene fluoride copolymer, tetrafluoroethylene-propylene copolymer, hexafluoropropylene-vinylidene fluoride copolymer, and the like. Ethylene fluoride-hexafluoropropylene-vinylidene fluoride copolymer is preferred.

The fluororubber can be produced, for example, by emulsion polymerization using a redox catalyst.

In the composition of the present invention, such component (I) and (II)
The ratio of the component and the component (III) is (I) / [(II) + (II
The weight ratio of I)] is 95/5 to 50/50. (I) + (II) +
When the ratio of (II) + (III) in (III) is less than 5% by weight, the composition does not exhibit sufficient heat resistance and oil resistance, and
When the content is more than 10% by weight, when the composition is crosslinked, the processability is deteriorated and good thermoplasticity is not exhibited, which is not preferable. Also (II)
The ratio of the component to the component (III) is such that the component (I) and the component (III) are satisfactorily compatibilized with each other, and the composition is provided with the excellent heat resistance and oil resistance of the fluororubber. + (II
The proportion of (II) in I) is preferably 10% by weight to 50% by weight.

In the composition of the present invention, α, β-unsaturated nitrile-
Cross-linking agents such as conjugated diene-based copolymers, for example, cross-linking agents such as organic peroxides, allyl compounds, sulfur, cross-linking aids such as oximes, zinc oxide, cross-linking accelerators such as magnesium oxide,
And / or fluororubber cross-linking agents such as amine carbamates, aminocinnamylidene amine cross-linking agents, bisphenol, hydroquinone, organic phosphonium salts, magnesium oxide, calcium hydroxide and other polyol cross-linking agents. Agent, organic peroxide, allyl compound,
A peroxide-based cross-linking agent composed of a metal oxide or the like can be added. The blending amount of such a cross-linking agent is not particularly limited, but to the extent that the thermoplasticity of the present composition is not impaired, that is, the α, β-unsaturated nitrile-conjugated diene copolymer and / or
Alternatively, 70 to 100% of the optimum compounding amount for crosslinking fluororubber is preferable.

If necessary, the composition of the present invention may be mixed with a thermoplastic resin such as polyethylene or polypropylene, a filler such as carbon black or silica, an oil or the like.

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. The order of mixing is not particularly limited, but α, β-
After mixing an unsaturated nitrile-conjugated diene copolymer and / or a hydrogenated product thereof with a fluororubber, the hydrogenated block copolymer and / or the hydrogenated block copolymer containing a carboxylic acid group or a derivative group thereof The method of mixing with the combined modified product is
It is preferable for obtaining good mixability.

When the component (II) and / or the component (III) is crosslinked, the method is not particularly limited, but a hydrogenated block copolymer, an α, β-unsaturated nitrile-conjugated diene-based copolymer and A method of adding a cross-linking agent or the like of the component at the same time as or after mixing the fluororubber to cross-link is preferable in order to obtain a cross-linked composition with good mixing.

〔The invention's effect〕

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 and fluororubber is provided. It can be obtained and can be very suitably used for various hoses that come into contact with fuel oil, hydraulic oil, lubricating oil, and various rolls that require oil resistance and heat resistance.

〔Example〕

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 was obtained by the method described in JP-A-59-133203, and bound styrene content was 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) 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 molecular weight was 150,000, molecular weight distribution was 1.04, and hydrogenation rate of the polybutadiene portion was 98%.

(1-3) In the same manner as (1-1), having a structure of polystyrene-hydrogenated polyisoprene-polystyrene, the amount of bound styrene is 30%, and the polyisoprene part before hydrogenation is 3,4-vinyl. A hydrogenated block copolymer having a binding amount 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.

(1-4) 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 molecular weight was 50,000, molecular weight distribution was 1.04, and hydrogenation rate of the polybutadiene portion was 99%.

(1-5) In the same manner as (1-1), (polystyrene-
It has the structure of hydrogenated polybutadiene ₄ Si, the amount of bound styrene is 30%,
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 thus obtained had 0.75 parts by weight of maleic anhydride added.

(2-2) Hydrogenated block copolymer obtained in (1-4)
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 (1-4)
2.5 parts by weight of glycidyl methacrylate per 100 parts by weight,
Mix 0.5 parts by weight of di-tert-butyl peroxide,
With a twin-screw extruder with a vent of 45mmφ diameter set to ℃, while performing forced venting using a vacuum pump (Decompression degree: 750mm
HgG) denaturation reaction was performed. The modified hydrogenated block copolymer obtained was one in which 1.5 parts by weight of glycidyl methacrylate was added.

Examples 1 to 55 and Comparative Examples 1 to 32 Thermoplastic elastomer compositions having the compounding ratios shown in Tables 1 to 9 were prepared by using a roll at 180 ° C., and formed into a sheet having a thickness of about 2 mm.
After compression molding at 180 ° C., it was subjected to the following test. The results are shown in Tables 1-9.

Heat resistance: According to JIS K 6301 "Physical test method for vulcanized rubber", the above compression-molded sheet (hereinafter referred to as "press sheet") is punched out into a dumbbell-shaped No. 3 type test piece, and is used.
Tensile strength at 100 ℃ was measured by measuring the tensile strength at ℃, 70 ℃ and 100 ℃.
Those that hold 0% or more are ○, those below that value are ×
Evaluated as.

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, immersed in JIS No. 3 oil at 70 ° C for 1 hour, and then taken out. When the surface did not change before and after the immersion and the weight change before and after the immersion was 20% or less, it was evaluated as ◯, and when the surface was changed or the weight change exceeded this value, it was evaluated as x.

Weather resistance: In accordance with JIS K 1415 "Method for accelerated exposure test for plastic building materials", the above press sheet is punched out into dumbbell-shaped type 3 test piece, black panel temperature 63 ° C, spray cycle 12 minutes / 60 minutes After exposure in a sunshine weatherometer for 500 hours, it was taken out, and the retention of tensile strength before and after exposure was 95% or more and the surface condition did not change before and after exposure. ○, the retention rate was below this value or The change in surface condition was evaluated as x.

Thermoplastic: Melt flow rate (MFR) of each thermoplastic elastomer composition according to JIS K 7210 "Method for flow test of thermoplastics" is set under condition 14 (test temperature 230 ° C, test load).
2.16 kgf), and those with MFR of 0.1 or more were evaluated as ○, and those below this value were evaluated as ×.

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. Hydrogenated block copolymer and / or the modified hydrogenated block copolymer (I) containing a carboxylic acid group or a derivative group thereof, and α, β
-Unsaturated nitrile-conjugated diene copolymer and / or its hydrogenated product (II) and fluororubber (III) as essential components, and the weight ratio of (I) / [(II) + (III)] Is 95/5
A thermoplastic elastomer composition of about 50/50. 2. The thermoplastic elastomer composition according to claim 1, which is obtained by crosslinking at least (II) and / or (III).