JP2003113286A - Rubber composition improved in gripping property and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a rubber composition improved in wet gripping properties without spoiling the breaking strength of a tire. SOLUTION: This rubber composition comprises an isobutylene-based block copolymer (A) containing unsaturated bonds having crosslinking functional groups and consisting of a polymer block (a) mainly comprising isobutylene and a polymer block (b) mainly comprising an aromatic vinyl-based compound, a thermoplastic resin (B) and at least one species of rubber component (C) out of natural rubber, diene-based polymer rubber, olefin-based polymer rubber. The copolymer (A) is crosslinked during melting and kneading with the resin (B).

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a rubber composition for tires containing an isobutylene block copolymer having improved wet grip properties.

[0002]

2. Description of the Related Art In recent years, there has been an increasing demand for lower fuel consumption of automobiles, especially for reduction of rolling resistance of tires, and tires having excellent frictional resistance (wet grip) on wet road surfaces have been demanded from the demand of running stability. Is required. Wet grip is the hysteresis loss of the tread rubber (Tan δ)
It is effective to increase the loss tangent (Tan δ) in the vicinity of 0 ° C. under the frequency of 10 Hz, which is the condition of repeated deformation during running of the tire. By using a halogenated butyl rubber or a halide of a copolymer of polyisoprene and P-methylstyrene as a rubber composition for a tread used in a pneumatic tire in the field of automobiles as described above, a wet road surface is obtained without being hardened at a low temperature. A method of increasing the friction coefficient of is also known. As the prior art, for example, JP-A-7-304903, JP-A-8-225683, JP-A-9-324069 and the like have been reported. However, it is known in the prior art that ethanol is generated when silica and the coupling agent chemically react with each other, which adversely affects the tire manufacturing process. Particularly, in the case of butyl rubber, since the air permeability is excellent, the generated ethanol is likely to remain in the rubber system. Further, since the strength of butyl rubber is low, the silica is highly filled, and bubbles are generated by ethanol, spewing is likely to occur during tire vulcanization, and thus far, productivity was extremely poor.

[0003]

That is, the problem to be solved by the present invention is to provide a rubber composition for a tire which improves wet grip properties without impairing the breaking strength of the tire.

[0004]

That is, the present invention comprises a polymer block (a) mainly containing isobutylene and a polymer block (b) mainly containing an aromatic vinyl compound and having an unsaturated bond. At least one selected from the group consisting of an isobutylene block copolymer (A) containing a crosslinkable functional group, a thermoplastic resin (B), natural rubber, a diene polymer rubber and an olefin polymer rubber.
A rubber composition comprising a rubber component (C) as a seed, wherein the (A) is crosslinked during the melt-kneading with the (B), and the rubber composition has improved grip properties. It is preferable that (C) is crosslinked.

Next, (A) preferably has an allyl group at its terminal, and (A) is β-pinene, divinylbenzene, diisopropenylbenzene, α-pinene, limonene,
A copolymer of at least one selected from the group consisting of dicyclopentadiene, isoprene and 2,4-dimethyl-1,3-pentadiene is preferable.

When (A) and (B) are melt-kneaded, a hydrosilylation reaction can be used to dynamically crosslink, and a radical reaction using an organic peroxide or sulfur can be used. It can also be dynamically crosslinked.

Further, the thermoplastic resin (B) is an isobutylene block copolymer composed of a polymer block (A) mainly containing isobutylene and a polymer block (B) mainly containing an aromatic vinyl compound. It can also be an olefin resin. On the other hand, the production method of the present invention comprises a polymer block (a) mainly containing isobutylene and a polymer block (b) mainly containing an aromatic vinyl compound, and contains a crosslinkable functional group having an unsaturated bond. A step (1) in which the isobutylene-based block copolymer (A) and the thermoplastic resin (B) are cross-linked while being melt-kneaded, and the composition obtained in the step (1) are mixed with natural rubber,
The rubber composition obtained in the step (2) and the step (2) in which a rubber composition is obtained by melt-kneading with at least one rubber component (C) selected from a diene polymer rubber and an olefin polymer rubber. A method for producing a rubber composition having improved grip properties, which comprises the step (3) of cross-linking.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The rubber composition of the present invention comprises a polymer block (a) mainly containing isobutylene and a polymer block (b) mainly containing an aromatic vinyl compound and has an unsaturated bond. An isobutylene-based block copolymer (A) having a crosslinkable functional group, and a thermoplastic resin (B),
A rubber composition comprising at least one rubber component (C) selected from natural rubber, diene polymer rubber, and olefin polymer rubber, wherein the (A) is melted with the (B). It is characterized in that it is crosslinked during kneading.

The cross-linkable functional group-containing isobutylene block copolymer (A) having an unsaturated bond, which can be used in the present invention, comprises an isobutylene-based polymer block (a) and an aromatic vinyl compound. It comprises a polymer block (b) as a main component and has a crosslinkable unsaturated bond.

The isobutylene-based polymer block (a) of the cross-linkable functional group-containing isobutylene block copolymer (A) of the present invention means isobutylene of 50% by weight or more, preferably 70%. It refers to a block which accounts for at least wt%, more preferably at least 90 wt%. In a polymer block mainly composed of isobutylene,
The monomer other than isobutylene is not particularly limited as long as it is a monomer component capable of being cationically polymerized, but is described later, such as aromatic vinyls, aliphatic olefins, dienes, vinyl ethers, pinene and its analogs. Examples thereof include monomers. These may be used alone or in combination of two or more. The polymer block (b) mainly composed of the aromatic vinyl compound of the cross-linkable functional group-containing isobutylene block copolymer (A) having an unsaturated bond means that the aromatic vinyl compound is 50% by weight or more, preferably Is 70
It refers to a block which accounts for at least wt%, more preferably at least 90 wt%. The monomer other than the aromatic vinyl compound in the polymer block mainly composed of the aromatic vinyl compound is not particularly limited as long as it is a cation-polymerizable monomer. Examples thereof include monomers such as vinyl ethers, vinyl ethers, pinene and their analogs.

As the aromatic vinyl compound, styrene, o-, m- or p-methylstyrene, α-methylstyrene, β-methylstyrene, 2,6-dimethylstyrene, 2,4-dimethylstyrene, α- Methyl-o-methylstyrene, α-methyl-m-methylstyrene, α-methyl-p-methylstyrene, β-methyl-o-methylstyrene, β-methyl-m-methylstyrene, β-methyl-p-methyl Styrene, 2,4,6-trimethylstyrene, α-methyl-2,6-dimethylstyrene, α-methyl-2,4-dimethylstyrene, β-methyl-2,6-
Dimethylstyrene, β-methyl-2,4-dimethylstyrene, o-, m- or p-chlorostyrene, 2,6-dichlorostyrene, 2,4-dichlorostyrene, α-chloro-o-chlorostyrene, α- Chloro-m-chlorostyrene, α-chloro-p-chlorostyrene, β-chloro-
o-chlorostyrene, β-chloro-m-chlorostyrene, β-chloro-p-chlorostyrene, 2,4,6-trichlorostyrene, α-chloro-2,6-dichlorostyrene, α-chloro-2,4 -Dichlorostyrene, β-chloro-2,6-dichlorostyrene, β-chloro-2,4
-Dichlorostyrene, o-, m- or p-t-butylstyrene, o-, m- or p-methoxystyrene, o-,
m- or p-chloromethylstyrene, o-, m- or p
-Bromomethylstyrene, styrene derivatives substituted with a silyl group, indene, vinylnaphthalene and the like. These may be used alone or in combination of two or more.

Among the above compounds, it is preferable to use at least one monomer selected from the group consisting of styrene, α-methylstyrene, p-methylstyrene and indene. From the viewpoint of cost, styrene and α-methylstyrene are preferable. It is particularly preferable to use styrene or a mixture thereof.

As the aliphatic olefins, ethylene,
Propylene, 1-butene, 2-methyl-1-butene, 3
-Methyl-1-butene, pentene, hexene, cyclohexene, 4-methyl-1-pentene, vinylcyclohexane, octene, norbornene and the like can be mentioned. These may be used alone or in combination of two or more.

Examples of the dienes include butadiene, isoprene, 2,4-dimethyl-1,3-pentadiene, hexadiene, cyclopentadiene, cyclohexadiene, dicyclopentadiene, divinylbenzene, diisopropenylbenzene and ethylidene norbornene. . These may be used alone or in combination of two or more.

The vinyl ethers include methyl vinyl ether, ethyl vinyl ether, (n-, iso) propyl vinyl ether, (n-, sec-, tert-,
Iso) butyl vinyl ether, methyl propenyl ether, ethyl propenyl ether and the like can be mentioned. These may be used alone or in combination of two or more. Regarding the ratio of the polymer block (a) mainly composed of isobutylene and the polymer block (b) mainly composed of an aromatic vinyl compound in the isobutylene-based block copolymer (A) containing a crosslinkable functional group having an unsaturated bond Is not particularly limited, but from the standpoint of balance between physical properties and processability, the polymer block (a) mainly containing isobutylene is 98 to 40 parts by weight, and the polymer block (b) mainly containing an aromatic vinyl compound is 2 parts by weight. Is preferably 60 to 60 parts by weight, and the polymer block (a) mainly containing isobutylene is 95 to 60 parts by weight.
It is particularly preferable that the amount of the polymer block (b) mainly containing an aromatic vinyl compound is 5 to 40 parts by weight.

From the viewpoint of tire characteristics, when the proportion of the polymer block mainly containing isobutylene is increased, the wet grip property is improved, but the fracture properties, that is, the wear resistance and the rolling resistance tend to be lowered.

The preferred structure of the crosslinkable functional group-containing isobutylene block copolymer (A) having an unsaturated bond of the present invention is mainly isobutylene from the viewpoint of the physical properties and processability of the resulting composition. A structure composed of at least one polymer block (a) and at least two polymer blocks (b) mainly containing an aromatic vinyl compound is preferable. The structure is not particularly limited, but examples thereof include a triblock copolymer formed from (b)-(a)-(b), and a multiblock copolymer having repeating {(b)-(a)} units. Polymer, and (b)-(a)
It is possible to use at least one kind selected from star-shaped polymers having a diblock copolymer of as an arm. Further, an isobutylene block copolymer (A)
In addition to the above structure, the polymer contains at least one of a polymer mainly containing isobutylene, a polymer mainly containing an aromatic vinyl compound, and a diblock copolymer (a)-(b). May be. However, from the viewpoint of physical properties and processability, a polymer block (a) mainly containing isobutylene contained in the isobutylene block copolymer (A).
50% by weight or more of the structure having at least one of the above and at least two polymer blocks (b) mainly containing an aromatic vinyl compound.

The weight average molecular weight of the isobutylene block copolymer (A) containing a crosslinkable functional group having an unsaturated bond is not particularly limited, but is preferably 3,000 to 500,000, and 5,000 to 100, 000 is particularly preferred. When the weight average molecular weight is less than 3,000, mechanical properties and the like are not sufficiently exhibited, and when it exceeds 500,000, the moldability and the like are largely deteriorated.

The unsaturated bond in (A) is represented by pinene and its analogs (α-pinene, β-pinene, limonene), dicyclopentadiene, divinylbenzene, diisopropenylbenzene, isoprene and 2,4-dimethyl-1. , 3
It is preferably obtained by copolymerizing a compound such as pentadiene which may have an unsaturated bond after the polymerization. Among these, β-pinene, divinylbenzene, and 2,4-dimethyl-1,3-pentadiene are particularly preferable because they are easily copolymerized. It is also preferable to obtain it by introducing an unsaturated bond, that is, an alkenyl group, at the terminal.

The method for producing the isobutylene-based block copolymer is not particularly limited, and a known polymerization method can be used. In order to obtain a block copolymer having a controlled structure, the following general formula ( In the presence of the compound represented by I), it is preferable to polymerize a monomer having isobutylene as a main component and a monomer component having no isobutylene as a main component such as an aromatic vinyl monomer. (CR ¹ R ² X) _n R ³ (I) [In the formula, X represents a substituent selected from the group consisting of a halogen atom, an alkoxyl group having 1 to 6 carbon atoms and an acyloxyl group having 1 to 6 carbon atoms. Represent R ¹ and R ² are respectively
It represents a hydrogen atom or a monovalent hydrocarbon group having 1 to 6 carbon atoms.
R ¹ and R ² may be the same or different. Further, a plurality of R ¹ and R ² may be the same or different. R ³ represents a polyvalent aromatic hydrocarbon group or a polyvalent aliphatic hydrocarbon group which can have n substituents. n represents a natural number of 1 to 6. Examples of the halogen atom include chlorine, fluorine, bromine, iodine and the like. The alkoxyl group having 1 to 6 carbon atoms is not particularly limited, and examples thereof include a methoxy group, an ethoxy group, an n- or isopropoxy group, and the like. The acyloxyl group having 1 to 6 carbon atoms is not particularly limited, and examples thereof include an acetyloxy group and a propionyloxy group. The hydrocarbon group having 1 to 6 carbon atoms is not particularly limited, and examples thereof include a methyl group, an ethyl group and n-
Alternatively, an isopropyl group and the like can be mentioned.

The compound represented by the above general formula (I) serves as an initiator and is considered to generate a carbon cation in the presence of a Lewis acid or the like and serve as a starting point of cationic polymerization. Examples of the compound represented by formula (I) used in the present invention include the following compounds.

(1-chloro-1-methylethyl) benze
The C₆H_FiveC (CH₃)₂Cl 1,4-bis (1-chloro-1-methylethyl) benze
The 1,4-Cl (CH₃)₂CC₆H_FourC (CH₃)₂Cl 1,3-bis (1-chloro-1-methylethyl) benze
The 1,3-Cl (CH₃)₂CC₆H_FourC (CH₃)₂Cl 1,3,5-tris (1-chloro-1-methylethyl)
benzene 1,3,5- (ClC (CH₃)₂)₃C₆H₃ 1,3-bis (1-chloro-1-methylethyl) -5-
(Tert-butyl) benzene 1,3- (C (CH
₃)₂Cl)₂-5- (C (CH₃)₃) C₆H₃ Among these, particularly preferred is 1-chloro-1-methyl.
Luethylbenzene [C ₆H_FiveC (CH₃)₂Cl], bis
(1-Chloro-1-methylethyl) benzene [C ₆H
_Four(C (CH₃)₂Cl)₂], Tris (1-chloro-1-
Methylethyl) benzene [(ClC (CH₃)₂)₃C₆H
₃]. [Note that 1-chloro-1-methylethylben
Zen is α-chloroisopropylbenzene, 2-chloro
-2-Propylbenzene or cumyl chloride
Called bis (1-chloro-1-methylethyl) benze
Is bis (α-chloroisopropyl) benzene, bis
(2-chloro-2-propyl) benzene or dicum
Also called luchloride, tris (1-chloro-1-me
Tylethyl) benzene is tris (α-chloroisopropene).
Pill) benzene, tris (2-chloro-2-propyl)
Also called benzene or tricumyl chloride
]].

In the above polymerization reaction, a Lewis acid catalyst can coexist. Any Lewis acid can be used as long as it can be used for cationic polymerization, such as TiCl ₄ , TiBr.
₄ , BCl ₃ , BF ₃ , BF ₃ · OEt ₂ , SnCl ₄ , SbCl ₅ ,
SbF ₅ , WCl ₆ , TaCl ₅ , VCl ₅ , FeCl ₃ , ZnB
Metal halides such as r ₂ , AlCl ₃ , AlBr ₃ ; Et ₂
Organic metal halides such as AlCl and EtAlCl ₂ can be preferably used. Above all, considering the catalytic ability and industrial availability, TiCl ₄ , B
Cl ₃ and SnCl ₄ are preferred. The amount of the Lewis acid catalyst used is not particularly limited and can be set in consideration of the polymerization characteristics or the polymerization concentration of the monomers used.

In the above polymerization reaction, if necessary, an electron donor component may coexist. This electron donor component is believed to have the effect of stabilizing the growing carbocation during cationic polymerization.
The addition of an electron donor produces a polymer with a controlled structure with a narrow molecular weight distribution. The electron donor component that can be used is not particularly limited, and examples thereof include pyridines, amines, amides, sulfoxides, esters, and metal compounds having an oxygen atom bonded to a metal atom.

The above-mentioned polymerization reaction can be carried out in an organic solvent, if necessary, and the organic solvent can be used without particular limitation as long as it does not substantially inhibit the cationic polymerization. Specifically, halogenated hydrocarbons such as methyl chloride, dichloromethane, chloroform, ethyl chloride, dichloroethane, n-propyl chloride, n-butyl chloride and chlorobenzene; benzene, toluene, xylene,
Alkylbenzenes such as ethylbenzene, propylbenzene and butylbenzene; linear aliphatic hydrocarbons such as ethane, propane, butane, pentane, hexane, heptane, octane, nonane and decane; 2-methylpropane,
2-methylbutane, 2,3,3-trimethylpentane,
Branched aliphatic hydrocarbons such as 2,2,5-trimethylhexane; cycloaliphatic hydrocarbons such as cyclohexane, methylcyclohexane, ethylcyclohexane; paraffin oil obtained by hydrogenating and refining petroleum fractions. it can.

These solvents are used alone or in combination of two or more in consideration of the balance between the polymerization characteristics of the monomers constituting the block copolymer and the solubility of the resulting polymer. The amount of the solvent used is such that the concentration of the polymer is 1 to 5 in consideration of the viscosity of the obtained polymer solution and the ease of heat removal.
It is determined to be 0 wt%, preferably 3 to 35 wt%. In the actual polymerization, the respective components are mixed under cooling, for example, at a temperature of -100 ° C or higher and lower than 0 ° C. To balance energy cost and polymerization stability,
A particularly preferred temperature range is -30 ° C to -80 ° C.

The unsaturated bond of the present invention is not particularly limited as long as it is a group which is active in the crosslinking reaction of the component (A) to achieve the object of the present invention, that is, an alkenyl group. . Specific examples thereof include vinyl groups, allyl groups, methyl vinyl groups, propenyl groups, butenyl groups, pentenyl groups, aliphatic unsaturated hydrocarbon groups such as hexenyl groups, cyclopropenyl groups, cyclobutenyl groups, cyclopentenyl groups, cyclohexenyl groups. Cyclic unsaturated hydrocarbon groups such as As a method of introducing an alkenyl group into the terminal of the isobutylene block copolymer of the present invention, a functional group such as a hydroxyl group as disclosed in JP-A-3-152164 and JP-A-7-304909 is used. A method of reacting a compound having an unsaturated group with the polymer to introduce an unsaturated group into the polymer can be mentioned. Further, in order to introduce an unsaturated group into a polymer having a halogen atom, a method of performing a Friedel-Crafts reaction with an alkenylphenyl ether, a method of performing a substitution reaction with allyltrimethylsilane in the presence of a Lewis acid, various phenols Examples of the method include a Friedel-Crafts reaction with and introducing a hydroxyl group, and then further performing the above-mentioned alkenyl group introducing reaction. Further, U.S. Pat. No. 4,316,973, JP-A-63-
It is also possible to introduce an unsaturated group at the time of polymerizing a monomer as disclosed in JP-A-105005 and JP-A-4-288309. Particularly, those having an allyl group introduced at the terminal by a substitution reaction with allyltrimethylsilane are preferable. Moreover, it is preferable that at least one alkenyl group is substituted at the end of the molecule per molecule. If the amount is less than this, it is difficult to obtain a composition having excellent physical properties.

The thermoplastic resin (B) is not particularly limited, but a component compatible with the component (A) is preferable.
From these things, isobutylene polymer, styrene resin, styrene elastomer, olefin resin,
It is preferably an olefin rubber. The isobutylene-based polymer is an isobutylene-based block copolymer that does not contain a crosslinkable functional group (same as component (A) except that it does not contain a crosslinkable functional group, but its primary structure is component (A)). Same as or different from each other), an isobutylene homopolymer, an isobutylene random copolymer (for example, an isobutylene-styrene random copolymer), and an isobutylene graft copolymer.
Examples of the styrene resin include polystyrene, high-impact polystyrene, methyl methacrylate-styrene resin, and ABS resin. Styrene-based elastomers include styrene-butadiene-styrene block copolymer (SBS), styrene-isoprene-styrene block copolymer (SIS), and styrene-ethylenebutylene-styrene block copolymer (SEBS) obtained by hydrogenating them. ) And styrene-ethylene propylene-styrene block copolymer (SEPS). Examples of the olefin resin include polyethylene having various densities, polypropylene homopolymer, polypropylene random copolymer, impact polypropylene, and polymethylpentene. As olefin rubber, butyl rubber,
Examples include chlorinated butyl rubber, brominated butyl rubber, ethylene-propylene rubber, and ethylene-propylene-diene rubber. As will be described later, the component (B) is the component (A).
The component (B) is selected according to the crosslinking system of the component (A), since it is preferable that the component (B) is not crosslinked during the crosslinking.

Examples of the rubber component (C) include natural rubber, diene polymer rubber and olefin polymer rubber. Examples of the diene polymer rubber include isoprene rubber, butadiene rubber, 1,2-polybutadiene, styrene-butadiene rubber, chloroprene rubber, and nitrile rubber. Examples of the olefin rubber include butyl rubber, chlorinated butyl rubber, brominated butyl rubber, ethylene-propylene rubber, and ethylene-propylene-diene rubber. Among these, a homopolymer of a diene compound or a copolymer of a diene compound and an aromatic vinyl compound is particularly preferable. The wet grip performance is considered to depend on the deformation near the surface of the tire. It has been known that this deformation near the surface is vibration of a very high frequency, and using temperature-frequency conversion, the wet grip property is represented by tan δ of about 0 ° C. at 10 Hz.
The tire rubber composition used in the present invention comprises a crosslinkable functional group-containing isobutylene-based block copolymer composed of a polymer block containing isobutylene as a main monomer component and a polymer block containing an aromatic vinyl compound as a main component. The composition is composed of the thermoplastic resin (B) and the rubber component (C) with the coalescence as the component (A), and the loss tangent (tan δ) obtained by dynamic viscoelasticity measurement of the composition in the 10 Hz tensile mode is 0 ° C
In addition to these components, any component may be blended as long as the composition is 0.5 or more.

When the cross-linkable group-containing isobutylene block copolymer as the component (A) is melt-kneaded with the component (C), for example, styrene-butadiene rubber, the system becomes uniform.
The tan δ at 10 Hz and 0 ° C. tends to be small. Therefore, before the component (A) is melt-kneaded with the component (C),
To make it a cross-linked product so that the system becomes non-uniform, that is, ta
It is necessary to make nδ large. For dispersibility in the component (C), the component (A) is preferably in a crosslinked particle state, and in order to obtain an appropriate crosslinked particle state,
It is preferable to dynamically crosslink the component (A) in the thermoplastic resin as the component (B). Alternatively, a composition in which the component (A) is preliminarily crosslinked and the component (B) is melt-kneaded is preferable, and a composition in which the component is dynamically crosslinked is particularly preferable.

As a means for crosslinking the isobutylene block copolymer (A) having an alkenyl group introduced at its terminal, known methods can be used without any particular limitation.
For example, thermal crosslinking by heating, hydrosilyl crosslinking, radical crosslinking with a radical initiator or sulfur can be performed.

A hydrosilyl group-containing compound is preferably used as a cross-linking agent for obtaining a cross-linked product of the isobutylene block copolymer (A) having an alkenyl group introduced at the terminal of the present invention. The hydrosilyl group-containing compound is not particularly limited and various compounds can be used. That is, the following general formula (II) or linear polysiloxane represented by _{^{(III); R 1 3 SiO-}} [Si (R 1) 2 O] a - [Si (H)
_{^{(R 2) O] A -}} [Si (R 2) (R 3) O] B -SiR 1 3
_{^{(II) HR 1 2 SiO- [}} Si (R 1) 2 O] a - [Si (H)
_{^{(R 2) O] A -}} [Si (R 2) (R 3) O] B -SiR 1 2
H (III) (In the formula, R ¹ and R ² represent an alkyl group having 1 to 6 carbon atoms or a phenyl group, and R ³ represents an alkyl group having 1 to 10 carbon atoms or an aralkyl group. A represents 0 ≦ a ≦ 100, A is 2 ≦ A ≦ 100, and B is an integer satisfying 0 ≦ B ≦ 100.) Cyclic siloxane represented by the general formula (IV);

[0033]

[Chemical 1]

[In the formula, R ⁴ and R ⁵ are alkyl groups having 1 to 6 carbon atoms or phenyl groups, and R ⁶ is 1 to 10 carbon atoms.
Represents an alkyl group or an aralkyl group. C is 0 ≦ C ≦
8, e is an integer of 2 ≦ e ≦ 10, f is an integer of 0 ≦ f ≦ 8,
In addition, 3 ≦ C + e + f ≦ 10 is satisfied. ] And other compounds can be used. Further, the above hydrosilyl group (Si
Among the compounds having a —H group), the compounds represented by the following general formula (V) are particularly preferable from the viewpoint of good compatibility with the component (A).

[0035]

[Chemical 2]

[Wherein g and h are integers and 2≤g + h≤
50, 2 ≦ g and 0 ≦ h. R ⁷ represents a hydrogen atom or a methyl group, and R ⁸ is a hydrocarbon group having 2 to 20 carbon atoms and is 1
It may have one or more aromatic rings. i is an integer of 0 ≦ i ≦ 5. The isobutylene block copolymer (A) having an alkenyl group introduced at the terminal and the cross-linking agent can be mixed at any ratio, but from the viewpoint of curability, the molar ratio of the alkenyl group to the hydrosilyl group is 0. It is preferably in the range of 2 to 5, and more preferably 0.4 to 2.5. When the molar ratio is 5 or more, sufficient crosslinking cannot be obtained due to insufficient crosslinking, and when it is less than 0.2, a large amount of active hydrosilyl groups remain in the composition even after crosslinking, so that the composition is uniform. Therefore, a strong composition cannot be obtained.

The cross-linking reaction between the component (A) and the cross-linking agent proceeds by mixing and heating the two components, but a hydrosilylation catalyst can be added to accelerate the reaction. Such a hydrosilylation catalyst is not particularly limited, and examples thereof include radical initiators such as organic peroxides and azo compounds, and transition metal catalysts.

The radical initiator is not particularly limited,
For example, di-t-butyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane,
Such as 2,5-dimethyl-2,5-di (t-butylperoxy) -3-hexyne, dicumyl peroxide, t-butylcumyl peroxide, α, α′-bis (t-butylperoxy) isopropylbenzene Dialkyl peroxides such as dialkyl peroxides, benzoyl peroxides, p-chlorobenzoyl peroxides, m-chlorobenzoyl peroxides, 2,4-dichlorobenzoyl peroxides, lauroyl peroxides, peracid esters such as perbenzoic acid-t-butyl, perdialkyl peroxides. Peroxydicarbonates such as diisopropyl carbonate, di-2-ethylhexyl perdicarbonate, 1,1-di (t-butylperoxy) cyclohexane, 1,1-di (t-butylperoxy) -3,3,5-trimethyl Peroxyke like cyclohexane It can be mentioned Lumpur and the like.

The transition metal catalyst is also not particularly limited, and examples thereof include platinum solids, alumina, silica, carbon black and the like in which platinum solids are dispersed, chloroplatinic acid, chloroplatinic acid and alcohols, aldehydes, Examples thereof include complexes with ketones, platinum-olefin complexes, and platinum (0) -diallyltetramethyldisiloxane complexes. Examples of catalysts other than platinum compounds include RhCl (PPh ₃ ) ₃ , R
hCl ₃ , RuCl ₃ , IrCl ₃ , FeCl ₃ , AlCl
₃ , PdCl ₂ · H ₂ O, NiCl ₂ , TiCl _{4 and the} like. These catalysts may be used alone or in combination of two or more kinds. The amount of the catalyst is not particularly limited, but it is 1 per 1 mol of the alkenyl group of the component (A).
It is preferably used in the range of 0 ^-1 to 10 ^-8 mol, and more preferably in the range of 10 ^-3 to 10 ^-6 mol. 10
^If it is less than ^-8 mol, crosslinking will not proceed sufficiently. Since the hydrosilylation catalyst is expensive, it is preferable not to use more than 10 ^-1 mol. Of these, platinum allyl siloxane is most preferable in terms of compatibility, crosslinking efficiency, and scorch stability.

For radical crosslinking, it is preferable to share a catalyst. A radical initiator such as an organic peroxide is used as the catalyst. The radical initiator is not particularly limited and includes, for example, di-t-butyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, 2,5-dimethyl-2,5-di ( t-butylperoxy) -3-hexyne, dicumyl peroxide, t-butylcumyl peroxide, α, α ′
Dialkyl peroxides such as bis (t-butylperoxy) isopropylbenzene, benzoyl peroxide, p-chlorobenzoyl peroxide, m-chlorobenzoyl peroxide, 2,4-dichlorobenzoyl peroxide, diacyl peroxides such as lauroyl peroxide, perbenzoic acid Peresters such as -t-butyl, diisopropyl percarbonate, di-2-percarbonate
Peroxydicarbonate, such as ethylhexyl,
1,1-di (t-butylperoxy) cyclohexane,
Mention may be made of peroxyketals such as 1,1-di (t-butylperoxy) -3,3,5-trimethylcyclohexane. Of these, 2,5-dimethyl-2,5-dimethyl ether is preferable in terms of odor, coloring and scorch stability.
Di- (tert-butylperoxy) hexane, 2,5
-Dimethyl 2,5-di- (tert-butylperoxy) hexyne-3 is preferred. The content of the organic peroxide is preferably 0.5 to 5 parts by weight with respect to 100 parts by weight of the component (A) when the organic peroxide is added.

The composition of the present invention may contain a crosslinking aid having an ethylenically unsaturated group in the crosslinking treatment with an organic peroxide. The ethylenically unsaturated group is, for example, a polyfunctional vinyl monomer such as divinylbenzene or triallyl cyanurate, or ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, trimethylolpropane trichloride. Examples thereof include polyfunctional methacrylate monomers such as methacrylate and allyl methacrylate. These may be used alone or in combination of at least two kinds. With such a compound, a uniform and efficient crosslinking reaction can be expected.

Among them, ethylene glycol dimethacrylate and triethylene glycol dimethacrylate are particularly easy to handle and have a solubilizing effect on organic peroxides.
Since it acts as a dispersion aid for the organic peroxide, the crosslinking effect by heat treatment is uniform and effective, and a balance between hardness and rubber elasticity can be obtained, which is preferable. The amount of the above-mentioned crosslinking aid added is preferably 20 parts by weight or less based on 100 parts by weight of the component (A). If it exceeds 20 parts by weight, gelation of the crosslinking aid by itself may lead to deterioration of the physical properties, and the cost becomes high. Examples of vulcanization accelerators that may be used together for sulfur crosslinking include 2,2-dithiobisbenzothiazole, 1,3-diphenylguanidine, tetramethylthiuram disulfide, zinc dimethylthiocarbamate, and mercaptobenzothiazyl disulfide. To be done. These are usually about 0.2 per 100 parts by weight of the rubber component.
~ 5 parts used. Examples of other crosslinking agents include phenolic resins and metal oxides. These are usually
About 0.5 to 10 parts are used for 100 parts by weight of the rubber component. Similarly, a crosslinking aid may be used.

In the rubber composition of the present invention, in addition to the above, compounding agents usually used in the rubber industry, such as fillers, plasticizers, tackifiers, etc., are appropriately compounded according to the purpose and application. be able to. Examples of the filler include carbon black, silica, filler, calcium carbonate, mica, flake graphite and the like. Examples of plasticizers include petroleum-based process oils such as paraffinic process oils, naphthene-based process oils, aromatic process oils, dialkyl dibasic acids such as diethyl phthalate, dioctyl phthalate, and dibutyl adipate, liquid polybutene, liquid poly A low molecular weight liquid polymer such as isoprene is exemplified, and among them, liquid polybutene, liquid polyisoprene, and aromatic process oil are preferable from the viewpoint of compatibility with the rubber component.

Examples of tackifying resins include rosin and rosin derivatives, polyterpene resins, aromatic modified terpene resins and their hydrides, terpene phenol resins, coumarone indene resins, aliphatic petroleum resins, alicyclic petroleum resins and Its hydride, aromatic petroleum resin and its hydride, aliphatic aromatic copolymer petroleum resin and its hydride,
Examples thereof include dicyclopentadiene-based petroleum resins and hydrogenated products thereof, and low molecular weight polymers of styrene or substituted styrene. In addition, the rubber composition of the present invention, according to the required properties according to each application, is usually used in the plastics industry, within a range that does not impair the physical properties, hindered phenol-based or hindered amine-based antioxidants and ultraviolet rays. Absorbent, light stabilizer, anti-aging agent, reaction retarder, surfactant,
A pigment, a reinforcing agent, a flame retardant and the like can be appropriately mixed.

The compounding amount of the crosslinkable functional group-containing isobutylene block copolymer (A) having an unsaturated bond and the thermoplastic resin (B) used in the present invention is not particularly limited and may be selected depending on the purpose. It can be appropriately selected, but when used in a rubber composition for a tire, for example, the rubber component (C) 10
It is preferable to add 1 to 50 parts by weight of (A) and (B) to 0 parts by weight. If the amount is less than 1 part by weight, it is difficult to obtain the effect of improving the wet grip property, and if it exceeds 50 parts by weight, rolling resistance tends to increase, which is not preferable. Regarding the compounding ratio of (A) and (B), the larger the amount of (A) is, the larger the effect of improving tan δ is, which is preferable. However, when the amount of (B) is too small, a suitable amount of (A) is obtained during dynamic crosslinking. It is difficult to obtain the crosslinked particles of A). Therefore, (A) / (B) = 99/1 to 20/80% by weight is preferable, and 95/5 to 40/60% by weight is more preferable.

In the present invention, preferably, a crosslinkable functional group having an unsaturated bond is composed of a polymer block (a) mainly containing isobutylene and a polymer block (b) mainly containing an aromatic vinyl compound. A step (1) in which the contained isobutylene-based block copolymer (A) and the thermoplastic resin (B) are cross-linked while being melt-kneaded, and the composition obtained in the step (1) is mixed with a natural rubber or a diene-based polymer. Step (2) of obtaining a rubber composition by melt-kneading with at least one rubber component (C) of a united rubber and an olefin polymer rubber, and crosslinking the rubber composition obtained in the step (2) From the step (3), a rubber composition having improved grip properties is produced.

When the step (1) is carried out using a closed kneading device or a batch kneading device such as Labo Plastomill, Brabender, Banbury mixer, kneader, roll, etc., a crosslinking agent and a crosslinking auxiliary agent are used. Adopting a method in which all components other than the crosslinking catalyst are mixed in advance and melt-kneaded until uniform, and then a crosslinking agent, a crosslinking auxiliary, and a crosslinking catalyst are added to the mixture to sufficiently stop the melt-kneading in the crosslinking reaction. You can

When a continuous melt-kneading device such as a single-screw extruder or a twin-screw extruder is used, all components other than the crosslinking agent, the crosslinking aid and the crosslinking catalyst are preliminarily used in the extruder or the like. Melt-kneading until uniform with the melt-kneading device, and pelletizing, dry blending the pellets with a cross-linking agent, a cross-linking auxiliary, and a cross-linking catalyst, and then melt-kneading with a melt-kneading device such as an extruder, A method of dynamically crosslinking the components, or a crosslinking agent and a crosslinking aid, all components other than the crosslinking catalyst are melt-kneaded by a melt-kneading device such as an extruder, and the crosslinking agent and the cross-linking agent from the middle of the extruder cylinder there. A cross-linking aid and a cross-linking catalyst are added, and the mixture is further melt-kneaded, and (A)
A method of dynamically crosslinking the components can be adopted.

In carrying out the above method of carrying out dynamic cross-linking simultaneously with melt-kneading, a temperature of 150 to 210 ° C. is preferable. Further, in this case, the component (B) does not cause a crosslinking reaction,
Only the component (A) can be crosslinked. The crosslinked product of the component (A) may be produced in advance, and the crosslinked product may be mixed with the component (B). In that case, the method exemplified below is preferably adopted.

For example, a cross-linking agent, a cross-linking aid, and a cross-linking catalyst are added to the above-mentioned component (A) and sufficiently kneaded at an appropriate temperature using a kneading machine or the like usually used for producing a rubber cross-linked product. The obtained kneaded product is subjected to a cross-linking reaction by using an appropriate cross-linking temperature and cross-linking time by using a pressing machine or the like, then cooled and pulverized to obtain a cross-linked product of the component (A). Can also be melt mixed with the component (B). At that time, as the melt mixing method of the crosslinked product of the component (A) and the component (B), any of the known methods conventionally used for producing a thermoplastic resin or a thermoplastic elastomer composition can be adopted, For example, Labo Plastomill, Banbury mixer,
It can be carried out using a single-screw extruder, a twin-screw extruder, or other melt-kneading equipment, and the melt-kneading temperature is 150 to 210
C is preferred.

In the steps (2) and (3), a method conventionally used in the rubber industry may be adopted. For example, first,
The mixture of the crosslinked product of the component (A) and the component (B), the rubber component (C), the crosslinking agent, and various compounding agents other than the crosslinking aid are mixed with a tumbler, a Henschel mixer, a ribo blender, and then an extruder, Knead with bumpers, rolls, etc.
At this time, it is desirable that the kneading temperature be appropriately changed from room temperature to 200 ° C. depending on the mixing ratio of the crosslinked product of the component (A), the component (B) and the component (C). This is because the glass transition temperature of the polymer block of the crosslinkable functional group-containing isobutylene block copolymer having an aromatic vinyl compound as a monomer is usually 100 ° C. or higher. This is because when the ratio of the united product (a) is high, the respective components are not sufficiently mixed. Therefore, it is preferable to knead at a higher temperature as the blending amount of (a) is higher. In order to crosslink the component (C), after kneading, a crosslinking agent and a crosslinking aid are added, and the mixture is further kneaded using the above apparatus.
At this time, the kneading temperature is preferably 80 ° C to 120 ° C for the purpose of suppressing the reaction of the crosslinking agent. Furthermore, if necessary, the rubber composition can be molded and crosslinked using a press machine, an injection molding machine or the like.

The structure and size of the tire using the rubber composition of the present invention are not particularly limited and can be selected as required. The wet grip, which is the object of the present invention, is most required for tires for passenger cars, and it is desirable to use it for this. When the tire tread has a multi-layer structure, it is preferable to use the rubber composition of the present invention as at least the outermost layer.

[0053]

The present invention will be described in more detail with reference to the following examples. It should be noted that the present invention is not limited to these embodiments, and various modifications can be made without departing from the scope of the invention. Prior to the examples, viscoelasticity measurement conditions will be described. (Measurement of Viscoelasticity) The dynamic viscoelastic properties of the mixture and the rubber composition containing the isobutylene block copolymer are the same as those of the above-mentioned mixture or composition (in the examples, the formulations shown in Table 1) Labo Plastomill ( Manufactured by Toyo Seiki Co., Ltd.
What was melt-kneaded at 170 ° C. and 50 rpm for 10 minutes was formed into a sheet by hot press molding, and the obtained sheet was
According to JIS K-6394 (Dynamic property test method for vulcanized rubber and thermoplastic rubber), 40 mm x 5 mm x 2 mm
One test piece was cut out and used, and the measurement was performed at a frequency of 10 Hz and a strain of 0.1%. The device used was a dynamic viscoelasticity measuring device DVA-200 (manufactured by IT Measurement and Control Co., Ltd.). At this time, the frequency needs to be 10 Hz, but this is because the wet grip characteristics are tan δ at 10 Hz and 0 ° C. when the time-temperature conversion rule of viscoelasticity is used.
This is because it correlates with the value.
It is known that the wet grip property is good. (Production Example 1) [Production of styrene-isobutylene-styrene block copolymer (SIBS)] The inside of the polymerization vessel of a 2 L separable flask was replaced with nitrogen, and then n-hexane (dried with molecular sieves was used with a syringe. 456.4 mL and butyl chloride (dried with molecular sieves) 656.3 m
L was added, the polymerization container was placed in a dry ice / methanol bath at -70 ° C. and cooled, and then a pressure-resistant glass liquefaction sampling tube with a three-way cock containing 232 mL (2871 mmol) of isobutylene monomer was made of Teflon (registered trademark). A liquid-feeding tube was connected, and the isobutylene monomer was fed into the polymerization container by nitrogen pressure. 0.647 g (2.8 mmol) of p-dicumyl chloride and 1.22 g (14 mmol) of N, N-dimethylacetamide were added. Next, a further 8.67 mL of titanium tetrachloride (79.1 m
(mol) was added to initiate polymerization. 2.5 from the start of polymerization
After stirring at the same temperature for an hour, about 1 mL of the polymerization solution was withdrawn from the polymerization solution for sampling. continue,
77.9 g (748 mmol) of styrene monomer that had been cooled to -70 ° C in advance, n-hexane 14.1
A mixed solution of mL and 20.4 mL of butyl chloride was added into the polymerization vessel. Two hours after the addition of the mixed solution, a large amount of water was added to terminate the reaction.

The reaction solution was washed twice with water, the solvent was evaporated,
The target block copolymer was obtained by vacuum-drying the obtained polymer at 60 ° C. for 24 hours. The molecular weight of the polymer obtained by the gel permeation chromatography (GPC) method was measured. Mw of block copolymer is 1
A block copolymer of 01,000 was obtained.

(Production Example 2) [Production of Modified Polystyrene-Polyisobutylene-Polystyrene Triblock Copolymer (ASIBS) Introduced with Alkenyl Group at Terminal] After purging the inside of a polymerization vessel of a 2 L separable flask with nitrogen, Using a syringe, add 480 mL of n-hexane (dried with molecular sieves) and 690 mL of butyl chloride (dried with molecular sieves),
After the polymerization container was placed in a -70 ° C dry ice / methanol bath and cooled, 201 mL of isobutylene monomer was added.
A Teflon (registered trademark) feed tube was connected to a pressure-resistant glass liquefaction collection tube with a three-way cock containing (2132 mmol), and isobutylene monomer was fed into the polymerization vessel by nitrogen pressure. p- Diquamilolide 2.6
g (11.2 mmol) and N, N-dimethylacetamide 1.22 g (14 mmol) were added. Next, 9.9 mL (90.0 mmol) of titanium tetrachloride was further added to initiate polymerization. After stirring at the same temperature for 1.5 hours from the start of the polymerization, about 1 mL of the polymerization solution was sampled from the polymerization solution for sampling. Subsequently, 52 g (499 mmol) of styrene monomer was added into the polymerization container. 45 minutes after the addition of the mixed solution, 12 ml (10.0 mmol) of allyltrimethylsilane was added. After stirring at the same temperature for 60 minutes, a large amount of water was added to terminate the reaction.

The reaction solution was washed twice with water, the solvent was evaporated,
The target block copolymer was obtained by vacuum-drying the obtained polymer at 60 ° C. for 24 hours. The molecular weight of the polymer obtained by the gel permeation chromatography (GPC) method was measured. Mw of block copolymer is 2
A block copolymer of 2500 was obtained.

(Example 1) SIBS produced in Production Example 1
(100 parts by weight), ASIBS produced in Production Example 2,
(150 parts by weight) was melt-kneaded for 5 minutes using a Labo Plastomill (manufactured by Toyo Seiki Co., Ltd.) set at 150 ° C., and then a crosslinking agent (average 5 hydrosilyl groups in the molecule and average 5).
A chain siloxane containing α-methylstyrene groups,
14 parts by weight), and kneading was continued for 5 minutes. Crosslinking catalyst (0-valent platinum 1,1,3,3-tetramethyl-1,
3-diallyldisiloxane complex, 1% xylene solution, 5
4 μL) was added, and the mixture was melt-kneaded to perform dynamic crosslinking.

Styrene-butadiene copolymer rubber (JS
RSL552, manufactured by JSR, abbreviated as SBR hereinafter. ),
Butadiene rubber (JSRBR01, manufactured by JSR, hereinafter B
Abbreviated as R. ), And the dynamically crosslinked product of SIBS and ASIBS produced above was kneaded for 15 minutes with a Labo Plastomill (manufactured by Toyo Seiki Co., Ltd.) at a mixing ratio shown in Table 1 to obtain a composition. . The rubber composition was compression molded at 150 ° C. to prepare a sheet. The moldability was extremely good.
A test piece measuring 6 mm in length × 5 mm in width × 2 mm in thickness was cut out from the sheet, and a loss tangent tan at 0 ° C. was measured using a dynamic viscoelasticity measuring device DVA-200 (manufactured by IT measurement control company).
δ was measured. The measurement frequency was 10 Hz.

Comparative Example 1 For comparison, a styrene-butadiene copolymer rubber and SIBS were compression molded at 150 ° C. to prepare a sheet. In the same manner as in Example 1, the loss tangent tan δ at 0 ° C was measured. Measurement frequency is 10Hz
And

Comparative Example 2 For comparison, only a styrene-butadiene copolymer rubber was compression molded at 150 ° C. to prepare a sheet. In the same manner as in Example 1, the loss tangent tan δ at 0 ° C was measured. The measurement frequency was 10 Hz.

(Comparative Example 3) Styrene-butadiene copolymer rubber (JSRSL552, manufactured by JSR Co., hereinafter SBR
Abbreviated. ), Butadiene rubber (JSRBR01, JSR
Made by the company, hereinafter abbreviated as BR ), ASI manufactured in Manufacturing Example 2
BS, crosslinking agent (chain siloxane containing an average of 5 hydrosilyl groups and an average of 5 α-methylstyrene groups in the molecule, 14 parts by weight), crosslinking catalyst (0-valent platinum 1,1,3,3)
Similarly to Example 1, 3-tetramethyl-1,3-diallyldisiloxane complex, 1% xylene solution, 54 μL) was kneaded for 15 minutes with a Labo Plastomill (manufactured by Toyo Seiki Co., Ltd.) set at 150 ° C. A composition was obtained. The rubber composition was compression molded at 150 ° C. to prepare a sheet. The loss tangent tan δ at 0 ° C was measured. The measurement frequency was 10 Hz.

[0062]

[Table 1]

In Examples, tan δ at 0 ° C. is higher than in Comparative Examples 1 and 2, that is, the wet grip property is improved. Further, the breaking properties are almost the same as or slightly lower than those of the rubber component alone, that is, the breaking properties are the same as those of the rubber component alone.

[0064]

The rubber composition of the present invention contains a dynamically crosslinked isobutylene-based triblock copolymer, so that the pneumatic composition has an excellent balance of contradictory properties such as wet grip and tire breaking strength. Can be used as a tire.

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Claims (11)

[Claims] 1. An isobutylene-based polymer comprising a polymer block (a) mainly composed of isobutylene and a polymer block (b) mainly composed of an aromatic vinyl compound and containing a crosslinkable functional group having an unsaturated bond. Block copolymer (A)
And a thermoplastic resin (B), and at least one rubber component (C) selected from the group consisting of natural rubber, diene polymer rubber and olefin polymer rubber, A rubber composition, wherein the (A) is crosslinked during the melt-kneading with the (B). 2. The rubber composition according to claim 1, wherein (C) is crosslinked. 3. The rubber composition according to claim 1, wherein (A) has an allyl group at the terminal. 4. (A) is β-pinene, divinylbenzene,
Diisopropenylbenzene, α-pinene, limonene, dicyclopentadiene, isoprene and 2,4-dimethyl-
The rubber composition according to claim 1 or 2, which is obtained by copolymerizing at least one selected from the group consisting of 1,3-pentadiene. 5. The rubber composition according to claim 1, wherein the rubber composition is dynamically crosslinked by utilizing a hydrosilylation reaction when melt-kneading (A) and (B). object. 6. A method of dynamically crosslinking by utilizing a radical reaction using an organic peroxide or sulfur when melt-kneading (A) and (B). The rubber composition according to any one of 1. 7. (B) is an isobutylene block copolymer comprising a polymer block (a) mainly containing isobutylene and a polymer block (b) mainly containing an aromatic vinyl compound. The rubber composition according to any one of 1 to 6. 8. The rubber composition according to claim 1, wherein (B) is an olefin resin. 9. A cross-linkable functional group-containing isobutylene block having an unsaturated bond, which comprises a polymer block (a) mainly containing isobutylene and a polymer block (b) mainly containing an aromatic vinyl compound. A step (1) in which the polymer (A) and the thermoplastic resin (B) are cross-linked while being melt-kneaded, and the composition obtained in the step (1) is a natural rubber,
The rubber composition obtained in the step (2) and the step (2) in which a rubber composition is obtained by melt-kneading with at least one rubber component (C) selected from a diene polymer rubber and an olefin polymer rubber. A method for producing a rubber composition having improved grip properties, which comprises the step (3) of cross-linking. 10. A tire tread made of the rubber composition according to claim 1. 11. A shoe sole made of the rubber composition according to claim 1.