KR20020095212A - Modified rubber, process for producing the same, and composition - Google Patents

Abstract

A modified rubber which has been modified with a compound having two or more epoxy groups per molecule and has a specific structure; and a process for producing a modified rubber which comprises copolymerizing a vinylaromatic hydrocarbon and a conjugated diene using an organolithium as an initiator by the solution polymerization method and modifying the resultant copolymer with a compound having two or more epoxy groups per molecule. Also provided are: a modified-rubber composition comprising a raw rubber comprising the modified rubber and silica compounded therewith; and a vibration-damping rubber and a footwear both obtained from the modified-rubber composition.

Description

Modified rubber, preparation method thereof and composition thereof {MODIFIED RUBBER, PROCESS FOR PRODUCING THE SAME, AND COMPOSITION}

Japanese Patent Laid-Open No. 287617/1991 is a thermoplastic polymer having a structure represented by general formula (AB) _n- X ( _wherein A represents a vinylaromatic polymer block and B represents a diene compound polymer block) as a block polymer. A polymer is proposed. However, thermoplastic elastomers of this kind have two or more independent vinylaromatic polymer blocks in the molecule and require excessively high processing temperatures due to the cohesion of the vinylaromatic polymer blocks. It is therefore difficult to mix such elastomers with silica, carbon black and the like and vulcanize the composition with sulfur.

Recently, many techniques have been proposed for producing a rubber composition for a tire designed to incorporate silica into a rubber to achieve resource saving and energy saving.

That is, in the above technique, instead of the incorporation of carbon black when preparing the tire tread rubber currently in use, silica or a combination of silica and carbon black is incorporated into the rubber to obtain a high resilience elasticity, Reduces energy loss by increasing the viscoelastic low temperature (0 ° C) tanδ, which improves wet slip resistance, and at the same time lowers the high temperature (50-70 ° C) tanδ, which reduces tire rolling resistance.

For example, a typical technique is proposed in US Pat. No. 5,227,425. In the above technique, silica is used as a reinforcing filler for SBR having a specific structure, and the rubber composition is kneaded under specific conditions to obtain a tread rubber composition having an improved balance between fuel economy and wet slip resistance.

In order to improve the dispersibility of silica in such rubber compositions, silane coupling agents such as bis (triethoxypropyl) tetrasulfide are used.

Furthermore, the terminal modification of rubber using various alkoxysilyl groups and the silica-containing rubber composition prepared by the above technique are disclosed in Japanese Patent Laid-Open No. 227908/1987, 53535/1996, 53576/1996, 225324 / 1997 et al. The technique is intended to improve the dispersibility of silica in rubber and to reduce the amount of silane coupling agent to be used.

The alkoxysilyl modified polymer is obtained by reacting a specific alkoxysilane compound with the end-active polymer obtained by anionic polymerization.

Rubber compositions according to the various techniques described above are primarily intended to improve the balance between wet slip and rolling resistance of a tire. That is, the technique is intended to increase the low temperature (0 ° C.) tan δ that modifies viscoelasticity to improve wet sliding resistance, and lower the high temperature (50-70 ° C.) tan δ that reduces rolling resistance.

However, such rubber compositions have the problem that, for example, the performance varies considerably with the conditions, for example, the changing ambient temperature. For example, rubbers in the low temperature range (eg 0 ° C.) have increased hardness due to increased tan δ in the low temperature range, and rubber elasticity, for example, rebound elasticity, decreases. In contrast, rubber in the high temperature range (50-70 ° C.) has a reduced tan δ, which leads to a decrease in hardness.

The present invention relates to a modified rubber, a process for producing the modified rubber, and a modified rubber composition containing the modified rubber, which provide a vulcanized rubber composition having excellent resistance to compression set (c-set) and viscoelastic temperature dependency. More specifically, the present invention relates to: modified rubbers containing vinylaromatic hydrocarbon / conjugated diene block copolymers of specific structures having modified ends with specific compounds containing epoxy groups; A process for producing a modified rubber produced by anionic polymerization, wherein the vinylaromatic hydrocarbon / conjugated diene block copolymer of a specific structure containing active lithium is modified by reaction with a compound having two or more epoxy groups per molecule; And a modified rubber composition obtained by mixing the modified rubber mainly with silica. The invention furthermore relates to anti-vibration rubber and footwear articles, each of which is obtained from the modified rubber composition and which is excellent in temperature dependence of resistance to compression set (c-set) and viscoelasticity.

In order to overcome the problems described above, the inventors have made extensive investigations on the distribution of vinylaromatic hydrocarbons in the vinylaromatic hydrocarbon / conjugated diene copolymers and the modifying groups therein. As a result, the modified rubber is obtained from a copolymer having a specific structure with respect to the distribution of the vinyl aromatic hydrocarbon by modifying the end of the vinyl aromatic hydrocarbon polymer block of the copolymer with a compound having two or more epoxy groups in the molecule. Silica compositions have been found to be particularly good in the temperature and torsional dependence of c-set and viscoelasticity. The present invention has been accomplished based on this finding.

That is, the present invention relates to a modified rubber containing a modified copolymer represented by the general formula (RB) _n- X obtained by modifying a copolymer having a (RB) structure, wherein the modified rubber is a vinylaromatic hydrocarbon total bond Amount of 5 to 60% by weight, 3 to 40% by weight of vinylaromatic hydrocarbon polymer block bond and 80% by weight or less of vinyl bond in the conjugated diene moiety, measured by GPC and coupled with the denaturing agent. Main peak molecular weight is 100,000 to 1,500,000 (wherein R represents a vinylaromatic hydrocarbon / conjugated diene random copolymer having 50% by weight or less of conjugated diene polymer or vinylaromatic hydrocarbon bonds; B is a vinylaromatic hydrocarbon polymer block) A vinylaromatic hydrocarbon / conjugated diene copolymer having a vinylaromatic hydrocarbon polymer block or a R / B weight ratio of from 30/70 to 97/3 N is an integer of 1 or more; X represents a modified moiety of a compound having two or more epoxy groups per molecule).

The present invention further relates to a process for producing a modified rubber comprising the following steps: A block copolymer having a (RB) structure comprising a vinylaromatic hydrocarbon and a conjugated diene by a solution polymerization method using an organolithium compound as an initiator. Manufacturing step; And modifying the copolymer by reacting the reactive end of the copolymer with a compound having two or more epoxy groups per molecule.

The present invention further provides modified rubber of the invention (or 1 to 80% by weight of at least one rubber selected from 99 to 20% by weight of modified rubber and natural rubber, polybutadiene rubber, styrene / butadiene rubber and polyisoprene rubber). It relates to a modified rubber composition containing 100 parts by weight of the original rubber containing) and 5 to 150 parts by weight of silica.

The present invention further relates to anti-vibration rubber and footwear articles, each obtained from a modified rubber composition.

Best Mode for Carrying Out the Invention

The invention will be explained in detail below.

The modified rubber of the present invention represented by general formula (RB) _n- X is formed from at least one vinylaromatic hydrocarbon and at least one conjugated diene. Examples of vinylaromatic hydrocarbons include styrene, α-methylstyrene, p-methylstyrene, and the like. Examples of conjugated dienes include 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene and the like.

In the modified rubber of the present invention, the total bond amount of the vinylaromatic hydrocarbon is 5 to 60% by weight, preferably 10 to 50% by weight. The total combined amount of vinylaromatic hydrocarbons of less than 5% by weight is undesirable in that the composition has too low mechanical strength. The total combined amount of vinylaromatic hydrocarbons in excess of 60% by weight is undesirable in that it results in a damaged c-set, a too high value of viscoelastic low temperature tan δ, and thus a damaged rubber elasticity.

Moreover, the bonding amount of the vinylaromatic hydrocarbon polymer block is 3 to 40% by weight, preferably 5 to 30% by weight. A vinyl aromatic hydrocarbon polymer block bond amount of less than 3% by weight is undesirable in that the temperature dependence and torsional dependence of viscoelasticity are enhanced. If the amount of the vinylaromatic hydrocarbon block exceeds 40% by weight, the modified rubber has an increased hardness and too high value of tanδ, resulting in reduced rubber elasticity and damaged c-set.

In the modified rubber of the present invention, the vinyl bond amount in the conjugated diene portion is 80 mol% or less, preferably 10 to 70 mol%, more preferably 10 to 65 mol%. The amount of vinyl bonds exceeding 80 mol% is not preferable in that vulcanized rubber is damaged in low temperature performance, abrasion resistance and the like.

The molecular weight of the modified rubber of the invention, represented by the general formula (RB) _n- X, determined by GPC and calculated for standard polystyrene, is 100,000 to 1,500,000 in terms of the main peak molecular weight of the portion coupled by the modifier. , Preferably from 150,000 to 1,200,000, more preferably from 200,000 to 1,000,000. The modified part is basically a branched structure because it is modified with a compound having two or more epoxy groups. Since the modified rubber is impaired in mechanical strength, dynamic properties, c-set, etc., a main peak molecular weight of less than 100,000 is undesirable for molecules coupled by denaturing agents. Its main peak molecular weight in excess of 1,500,000 is undesirable because the modified rubber has a markedly reduced modification rate and shows impaired processability when used as a composition.

In the modified rubber of the present invention, the molecular weight of the vinylaromatic polymer block before modification is preferably 5,000 to 50,000, preferably 7,000 to 40,000, more preferably 10,000 to 30,000. The molecular weight of the vinylaromatic hydrocarbon polymer block refers to the main peak molecular weight determined through gel permeation chromatography (GPC) measurements and calculations on standard polystyrene. If the vinylaromatic hydrocarbon polymer block has a too low molecular weight, the modified rubber tends to be undesirable, having increased temperature and torsional dependence of viscoelasticity. In the case where the vinylaromatic hydrocarbon polymer block has a too high molecular weight, the modified rubber has high hardness and reduced rubber elasticity, too high Mooney viscosity, and the like, which tends to be undesirable, resulting in impaired handling and the like. .

In the related art, vulcanized rubber compositions of block copolymers formed from conjugated diene compounds and vinylaromatic hydrocarbon compounds have reduced performance such as c-sets and dynamic properties by vinylaromatic hydrocarbon polymer blocks in rubber. In contrast, the modified rubber of the present invention has a high affinity for silica because of its structural properties, ie, the vinylaromatic hydrocarbon polymer block fragment in the rubber has been modified with a compound having two or more epoxy groups in the molecule. The modified rubber thus provides a composition with good dynamic properties.

The polymer partial structure R of the modified rubber of the present invention is a conjugated diene polymer or a random copolymer of vinylaromatic hydrocarbons and conjugated dienes. In the case of a random copolymer, the amount of its vinylaromatic hydrocarbon bond is at most 50% by weight, more preferably at most 40% by weight. Coupling amounts of vinylaromatic hydrocarbons in excess of 50% by weight are undesirable in that the modified rubber has too high values of tanδ at increased hardness and low temperature, resulting in damaged rubber elasticity and damaged c-set.

The polymer partial structure B of the modified rubber of the present invention is a vinylaromatic hydrocarbon polymer conjugate or vinylaromatic hydrocarbon / conjugated diene block copolymer having a vinylaromatic hydrocarbon polymer block at its end.

In the present invention, the polymer partial structure R and the polymer partial structure B of the modified rubber may be arranged in a so-called tapered-block distribution in which the complete block distribution or vinyl aromatic hydrocarbon bond amount continuously increases from R to B. .

Although the modified rubber of the present invention is represented by the general formula (RB) _n -X, the low molecular weight conjugated diene polymer or the low molecular weight conjugated to the terminal of the vinylaromatic hydrocarbon polymer block of the partial structure B in which the partial structure B is bonded to the modifying group X Modified rubbers having molecular weight conjugated diene / vinylaromatic hydrocarbon random copolymers also have satisfactory performance. However, the molecular weight of the low molecular weight polymer fragments bonded to partial structure B is less than 5,000, preferably less than 3,000, more preferably less than 2,500. If the low molecular weight polymer fragment has a molecular weight of 5,000 or more, the denaturing effect of coupling with the modifier to the vinylaromatic hydrocarbon polymer block is reduced, resulting in impaired viscoelasticity. In the modified rubber of the present invention, the copolymer of the (RB) structure before modification has a molecular weight of 30,000 to 500,000, preferably 80,000 to 350,000, more preferably 100,000 to 350,000. The molecular weight of the copolymer before denaturation refers to the main peak molecular weight determined through calculations for GPC and standard polystyrene. If the molecular weight of the copolymer before modification is less than 30,000, the modified rubber composition has poor mechanical strength. When its molecular weight exceeds 500,000, the composition tends to be undesirably reduced in processability and the like.

The rubber composition of the present invention comprises copolymer chains modified at the ends with compounds each having two or more epoxy groups per molecule. When the number of epoxy groups in the modifier is m, the modified rubber has a structure including a modifier in which 1 to m copolymer molecules of the (R-B) structure are bonded thereto. Substantially, the modified rubber of the present invention is a mixture of molecules each consisting of a modifier in which 1 to m copolymer molecules of the (R-B) structure are bonded thereto. The number n of copolymer molecules bonded to the modifier is on average 2 to 10, preferably 2 to 8, more preferably 2 to 6 is preferred.

In the modified rubber of the present invention, at least 20% by weight of the copolymer molecules of the (R-B) structure have been modified with compounds of two or more epoxy groups per molecule. The modification rate is preferably 40% by weight or more, more preferably 50% by weight or more.

When the modification rate is less than 20% by weight, the silica-containing composition of the present invention tends to be undesired with impaired c-set, increased temperature dependence of viscoelastic tanδ and torsional dependence.

The manufacturing method of the modified rubber of the present invention will be described.

The modified rubber of the present invention copolymerizes vinylaromatic hydrocarbons and conjugated dienes in an inert organic solvent using an organolithium compound as an initiator to prepare a copolymer having a (RB) structure, and its active lithium ends and at least two epoxy groups per molecule It can be prepared by reacting a compound having a denaturation thereof.

Preferred examples of polymerization solvents include inert organic solvents such as aliphatic hydrocarbons such as butane, pentane, hexane, and heptane, alicyclic hydrocarbons such as cyclopentane, cyclohexane, and methylcyclopentane, Aromatic hydrocarbons such as benzene, toluene, and xylene, mixtures thereof, and the like.

The amount of the polymerization solvent used is not particularly limited. However, the amount thereof is determined in consideration of the viscosity, handleability, economical efficiency and the like of the obtained polymer. The amount of solvent used is preferably about 1 to 25 times the total monomer amount. The solvent is sometimes used entirely before the start of the polymerization or additionally added during the polymerization.

Polar compounds may be added in small amounts as vinylating or randomizing agents. Examples thereof include ethers such as diethyl ether, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, tetrahydrofuran, and 2,2-bis (2-oxolaranyl) propane, amines such as tri Ethylamine and N, N, N ', N'-tetramethylethylenediamine, alkali metal alkoxides such as potassium amyl alcoholate and the like.

Such vinylating agents can be used as microstructure control agents for the diene moiety in the polymer in an appropriate amount depending on the desired value of the amount of binding of the vinyl.

Many vinylating agents further have an effective random effect in the copolymerization of vinylaromatic hydrocarbons and conjugated dienes. These can be used as substances which control the distribution of aromatic vinyl compounds or substances which control the amount of aromatic vinyl compound polymer blocks. For randomization, a method in which a portion of the conjugated diene described in Japanese Patent Laid-Open No. 140211/1984 is added intermittently during copolymerization can be used.

The polar compounds can be added collectively or in portions at the same time prior to the start of the polymerization, at the start, after the start and during the polymerization and the like. By addition during the polymerization or in part by addition, the vinyl distribution in the polymer with the vinyl block structure can be controlled.

Examples of organolithium compounds used as initiators during the polymerization of vinylaromatic hydrocarbons and conjugated dienes in the process for producing modified rubbers of the present invention include monolithium compounds such as ethyllithium, propyllithium, n-butyllithium, sec-butyl Lithium, tert-butyllithium, and phenyllithium, dilithium compounds such as 1,4-dirithio-n-butane and 1,3- (2-dithiothiohexyl) benzene, polyvinyl compounds, For example, polylithium compounds obtained by modifying a monolithium compound with divinylbenzene, diisopropenylbenzene and the like are included.

The amount of organolithium compound to be used depends on the degree of polymerization of the copolymer obtained. However, it is about 2 to 50 mg in terms of lithium amount per 100 g of monomer.

The organolithium compound may be used by a method which is added in batch as a polymerization initiator or by a method which is added in part to prepare polymers having different molecular chain lengths. Moreover, the organolithium compound may be used in a small amount of the required treatment for the polymerization solvent, the monomer and the like before the polymerization.

Examples of the compound having two or more epoxy groups per molecule used as the modifier in the present invention include diepoxy compounds represented by the following general formula (1-a).

[Wherein, R represents the following general formula (1-b), (1-c), or (1-d):

(Wherein R ₁ and R ₂ are hydrogen, an alkyl group having 1 to 20 carbon atoms, or a phenyl group; R ₃ is an alkylene group having 2 to 20 carbon atoms; n represents an integer of 0 to 10).

Specific examples thereof include bisphenol A diglycidyl ether represented by formula (2-a), bisphenol F diglycidyl ether represented by formula (2-b), and the like:

(Wherein n represents an integer of 0 to 10).

Examples thereof further include alkylene oxide-containing epoxy compounds, alicyclic epoxy compounds, carbocyclic compound-containing epoxy compounds and the like. Mixtures of two or more of the above compounds represented by general formula (1-a) can also be used.

Moreover, polyfunctional compounds represented by the following general formula (3-a) having diglycidylamino groups can also be used as preferred modifiers:

[Wherein, R ¹ and R ² are hydrocarbon groups having 1 to 20 carbon atoms or hydrocarbon groups having 1 to 10 carbon atoms having ether or tertiary amine; R ³ and R ⁴ are hydrogen, a hydrocarbon group having 1 to 20 carbon atoms, or a hydrocarbon group having 1 to 20 carbon atoms having an ether or tertiary amine; R ⁵ is a hydrocarbon group of 1 to 20 carbon atoms, or a hydrocarbon group of 1 to 20 carbon atoms having at least one functional group selected from ether, thioether, tertiary amine, epoxy, carbonyl, halogen and silicon; n is 1 to 6;

Specific examples of the diglycidylamino compound represented by the general formula (3-a) include diglycidyl aniline, diglycidyl-o-toluidine, tetraglycidyl-m-xylenediamine, tetraglycidyl- p-phenylenediamine, tetraglycidyl-1,3-bisaminomethylcyclohexane, tetraglycidyldiaminodiphenylmethane and the like.

Also useful above are epoxidized soybean oil, epoxidized linseed oil, epoxidized polybutadiene and the like.

The method of adding such a compound having two or more epoxy groups in the molecule as a modifier is not particularly limited, and after the completion of the polymerization to prepare a copolymer of the (RB) structure having active lithium at the end, the amounts of the modifiers added are collectively added. Thereby modifying the copolymer, a method in which a portion of the modifier is added separately during the polymerization to perform the modification, and the like. However, the timing at which the modifier is added after the end of the polymerization is preferably within 30 minutes after the end. By adding the denaturant as early as possible, a high denaturation rate is obtained.

The amount of modifier compound added is from 0.05 to 2.0 moles, preferably from 0.10 to 2.0 moles, more preferably from 0.20 to 2.0 moles per mole of initiator lithium. When the addition amount exceeds the lithium equivalent, the coupling denaturation is slightly reduced, but the amount of the uncoupled modified polymer is increased. As a result, the modified rubber has improved affinity for silica, and more preferred silica-containing compositions are obtained.

As mentioned above, the modification using the modifier compound added in an amount exceeding the lithium equivalent provides a modified rubber having a higher amount of residual epoxy groups. For example, it is possible to add a lithium compound after modification to open the epoxy groups and convert them to -OH or the like through subsequent treatment.

In the process of the invention, a copolymer of the (RB) structure is prepared, for example, by one-step or multi-stage batch polymerization or continuous polymerization, wherein the copolymer has two or more epoxy groups in the molecule as its active end and as a modifier. It is the method which modified | denatured by reacting the compound which has.

For example, the manufacturing method of the modified rubber | gum of this invention represented by general formula (RB) _n- X through 1 step polymerization is as follows. Nitrogen substitution is carried out, and a polymerization solvent and a conjugated diene and a vinyl aromatic hydrocarbon are all filled in the polymerization reactor equipped with a stirrer. A small amount of vinylating agent is further introduced as necessary. The organolithium compound is added to initiate the polymerization. In the case of one-step polymerization, the amount of terminal vinylaromatic hydrocarbon polymer block is determined by the total amount of the vinylaromatic hydrocarbon polymer block, the amount of vinylating agent, polymerization temperature and the like. Thus, the copolymer partial structure R consisting of randomly bonded vinylaromatic hydrocarbons is obtained in the first half of the polymerization. Thereafter, in the subsequent second half of the polymerization, copolymer B having a vinylaromatic hydrocarbon polymer block at the end is obtained. Thus, a copolymer of tape block (RB) structure is obtained. After that, a denaturant is added.

In the case of two-step polymerization, for example, the method is as follows. In step 1, a conjugated diene polymer or a random copolymer of conjugated diene and vinylaromatic hydrocarbons is obtained as polymer partial structure R. In the next two steps, a vinylaromatic hydrocarbon or conjugated diene and a vinylaromatic hydrocarbon monomer are added to obtain a polymer aromatic structure B, a vinylaromatic hydrocarbon polymer or a copolymer having a vinylaromatic hydrocarbon polymer block at the end. Thus, a copolymer of the structure (R-B) is produced. After that, a denaturant is added.

Furthermore, in the case of continuous polymerization, the method comprises the following steps: continuously introducing one or more one-stage monomers and organolithium initiators into the first polymerizer to obtain a polymer partial structure R; Continuously introducing the polymer solution and one or more two-stage monomers into the second polymerizer to obtain polymer partial structure B to obtain a copolymer of (R-B) structure; And then adding the denaturing agent.

The denaturation reaction usually ends instantaneously. However, a denaturation reaction period of about 1 to 120 minutes is generally required, depending on the diffusivity of the denaturant and the viscosity of the polymerization product.

Regarding the rate of denaturation, a higher amount of active lithium before denaturation results in a satisfactory high rate of denaturation. In terms of preventing the amount of active lithium from decreasing, it is preferable to use a polymerization temperature that is not too high. In addition, it is necessary to minimize the inertness by reducing impurities such as alkenes, acetylene compounds, water, dissolved oxygen, etc. in the starting materials.

The polymerization is carried out at a temperature of about 0 to 130 ° C. However, the polymerization temperature is preferably 20 to 120 ° C. The polymerization may be elevated temperature polymerization or isothermal polymerization.

The activated lithium in the modified rubber polymer solution thus obtained is decomposed using alcohol, water and the like as necessary. Known stabilizers of rubber, for example 2,6-di-tert-butyl-4-methylphenol (BHT), n-octadecyl 3- (4'-hydroxy-3 ', 5'-di-tert- Butylphenol) propinate, or 2-methyl-4,6-bis [(octylthio) methyl] phenol, is added to the solution, which is known in the art, for example hot press or drum dryer, steam Solvent removal and drying are carried out by using stipping or the like to complete the modified rubber.

The modified rubber composition containing silica and the original rubber containing the modified rubber thus obtained will be described.

The original rubber contains the modified rubber of the present invention in an amount of at least 20% by weight, preferably at least 40% by weight. As other rubber (s), one or more natural rubbers, polybutadiene rubbers, styrene / butadiene rubbers, polyisoprene rubbers and the like can be incorporated.

The proportion of modified rubber of the present invention of less than 20% by weight is undesirable in that the composition has increased temperature and torsional dependence of viscoelastic tanδ.

The amount of silica incorporated into the modified rubber composition of the present invention is 5 to 150 parts by weight, preferably 10 to 100 parts by weight, more preferably 20 to 80 parts by weight per 100 parts by weight of the original rubber.

If the amount of silica incorporated is less than 5 parts by weight, sufficient reinforcing effect is not obtained. If the amount of silica incorporated exceeds 150 parts by weight, an improvement in the temperature dependence and torsional dependence of viscoelasticity as well as a reduction in rubber elasticity, whose effect is an advantage of the present invention, cannot be obtained.

The silica used in the modified rubber composition of the present invention may be any wet silica, dry silica and synthetic silicate type silica. Small particle size silica has a high reinforcing effect. It is preferable to use one of the high aggregation type of small particle diameter.

In the modified rubber composition of the present invention, as long as the performance of silica is not impaired, carbon black and extender oil for rubber may be preferably used as other compounding components.

Various carbons may be used as the carbon black, for example, FT, SRF, FEF, HAF, ISAF, SAF, and the like. However, carbon blacks having a nitrogen-adsorption specific surface area of at least 50 m ² / g and a DBP absorption of 80 mL / 100 g are preferred.

The amount of carbon black to be incorporated is 0 to 50 parts by weight per 100 parts by weight of the original rubber, and the sum of carbon black and silica is 150 parts by weight or less.

A silane coupling agent can be added to the modified rubber composition of the present invention as a coupling agent between the original rubber and the silica. The amount of silane coupling agent added is 0 to 25 parts by weight, preferably 0 to 15 parts by weight, more preferably 0 to 10 parts by weight, per 100 parts by weight of the original rubber.

The amount of the silane coupling agent added in excess of 25 parts by weight per 100 parts by weight of the raw rubber is not preferable because of impaired reinforcement properties and increased cost.

Examples of the silane coupling agent used in the modified rubber composition of the present invention include bis [3- (triethoxysilyl) propyl] tetrasulfide, bis [3- (triethoxysilyl) propyl] disulfide, bis [2- (Triethoxysilyl) ethyl] tetrasulfide, 3-mercaptopropyltrimethoxysilane, 3-triethoxysilylpropyl-N, N-dimethylthiocarbamoyl tetrasulfide, 3-triethoxysilylpropyl Benzothiazole tetrasulfide and the like.

The modified rubber in the modified rubber composition of the present invention has an excessively high affinity for silica. Therefore, it is possible to reduce the amount of silane coupling agent to less than 20% by weight of its conventional amount in silica-containing compositions of unmodified rubber.

In preparing the modified rubber composition of the present invention, the kneading temperature of the rubber, silica and other compounding components is in the range of 130 to 180 ° C, preferably 135 to 170 ° C. It is preferable to perform the kneading so that the silica forms a sufficient bond with the rubber.

As the extender oil for rubber, aromatic, naphthenic, and paraffinic extender oils used so far may be used. Also useful above are rubber-extending oils, such as MES, T-DAE, T-RAE, which have a reduced content of multinuclear aromatic components and are less environmentally harmful. The amount of extender oil for rubber used is increased or decreased depending on the amount of silica incorporated or silica and carbon black incorporated. Extending oils are used to control the modulus and other properties of the vulcanized composition. Such rubber extender oil can be added to the rubber solution resulting from the production of the modified rubber to complete the rubber as an oil-extension modified rubber.

The amount of the extender oil for rubber to be incorporated is 0 to 100 parts by weight, preferably 5 to 60 parts by weight, per 100 parts by weight of the rubber. When the amount thereof exceeds 100 parts by weight, too low hardness and deterioration of c-set, wear resistance and the like are caused.

In addition to the above, vulcanizing agents and vulcanizing accelerators are used as fillers in amounts of 1 to 20 parts by weight per 100 parts by weight of the original rubber. Sulfur is used as a typical vulcanizing agent. Other useful vulcanizing agents are sulfur-containing compounds, peroxides and the like.

As the vulcanization accelerator, sulfenamide compounds, guanidine compounds, thiuram compounds and the like are used in the required amounts.

In addition to the above, rubber chemicals such as zinc white, stearic acid, vulcanization aids, antioxidants, processing aids and the like are suitable for the purpose, for example, per 100 parts by weight of rubber. 0.1 to 20 parts by weight is added.

The modified rubber composition of the present invention kneads the raw rubber with an silica and other ingredients such as carbon black, silane coupling agent, rubber extender oil and rubber chemicals through an internal mixer, and further vulcanizing agents, e.g. For example, it can manufacture by mixing sulfur, a vulcanization accelerator, etc. using an internal mixer or a mixing roll. The composition is molded and then vulcanized using a vulcanizer under pressure at a temperature of 140-170 ° C. to give good performance.

The modified rubber of the present invention described above is blended with silica and silane coupling agent, further carbon black, rubber extender oil and another filler, and provided in the form of a vulcanized rubber composition. The modified rubber composition is suitable for use in a variety of tire applications, anti-vibration rubber, shoe products, belts and other industrial products. Due to the nature of the bound functional groups thereof, the modified rubber of the present invention is an olefin resin, styrene resin, acrylate resin, vinyl chloride resin, polyamide resin, polyester resin, polycarbonate resin, poly (phenylene ether) Resin, poly (phenylene sulfide) resin, polyacetal resin, polyurethane resin and the like can be used as a modifier. When used in combination with asphalt in appropriately selected proportions, modified rubbers can also be used for road pavement, waterproofing, rust protection, automotive primer coating, roofing, pipe coating, connection applications and the like.

The present invention will be described in detail below with reference to Examples, but the scope of the present invention should not be construed as being limited by the Examples.

The analysis of the example samples and the comparative example samples of the modified rubber of the present invention and the measurement of the physical properties of the composition were carried out by the following method.

(1) styrene bond amount

The rubber sample was dissolved in chloroform and the solution was measured for absorption at UV 250 nm due to the phenyl group of styrene. The absorption was measured by weight percent styrene bond compared to that of standard polystyrene.

(2) microstructure of butadiene moiety

Rubber samples were dissolved in carbon disulfide and the solution was analyzed by FT-IR in the range of 600 to 1,000 cm ⁻¹ using a solution cell. The amount of vinyl bonds, cis bonds, and trans bonds in the butadiene moiety was determined from the absorption at the indicated wavelengths using Hampton's formula.

(3) styrene block amount

Rubber samples were dissolved in chloroform and decomposed with osmium oxide. A precipitate formed from there with methanol and the amount of styrene blocks in terms of weight percent was determined from the weight of the precipitate.

(4) GPC peak molecular weight of modified rubber and unmodified copolymer rubber in terms of standard polystyrene

Modified or unmodified rubber samples were dissolved in tetrahydrofuran (THF). The solution was analyzed by gel permeation chromatography (GPC) using a styrene-based nonpolar column and RI measurements. Molecular weights were determined by comparison with standard polystyrene.

(5) GPC peak molecular weight of styrene block

The styrene block sample obtained in (3) through decomposition with osmium oxide was measured under the GPC conditions used in (4) to determine the GPC peak molecular weight of the styrene block.

(6) Modification rate of modified rubber

The modified rubber sample was dissolved in THF and an internal standard was added. The resulting solution was analyzed by GPC using the non-polar column and silica-based polar column used in (4), and the rate of modification of the rubber was eluted between the samples. Measured from the difference of the amount.

(7) conversion of monomer

The polymerization solution obtained by sampling from the autoclave during the polymerization was vacuum dried to determine the solids content of the polymerization solution. The solids content measured at the end of the polymerization was 100% by weight.

(8) conversion of styrene

The amount of unreacted styrene monomer in the polymerization solution obtained by sampling from the autoclave during the polymerization was measured by gas chromatography.

[Production of Modified Rubber of Example and Rubber of Comparative Example]

Modified rubber 1

The atmosphere in a 10L autoclave fitted with a hot water jacket and a stirrer was sufficiently exchanged with nitrogen. It was charged with 4.5 kg of cyclohexane, 0.25 kg of styrene and 0.75 kg of 1,3-butadiene, each of which was dehydrated with activated alumina. The contents were heated to 52 ° C. with stirring and 0.76 g of n-butyllithium (20 wt% cyclohexane solution; then applied equally) to initiate polymerization. The polymerization temperature reached 91 ° C. Two minutes after the maximum polymerization temperature, 4.4 g of tetraglycidyl-1,3-bisaminomethylcyclohexane (90 wt% cyclohexane solution; applied equally thereafter) was added and the denaturation reaction was carried out for 10 minutes. Was performed. 10 ml of water / methanol (1/5 by volume) as active-lithium decomposer were added and mixed with the modified rubber polymerization solution thus obtained. Thereafter, 2 g of BHT was added thereto as a stabilizer and mixed. The mixture was solvent removed and dried using a drum dryer to give a solid modified rubber.

The reaction mixture in the autoclave was taken during polymerization to obtain several samples for monomer conversion measurements, and the samples were analyzed to determine the amount of styrene bonds and styrene blocks at each monomer conversion. It was found that the polymer obtained at the conversion up to about 80% by weight was a random copolymer R with an styrene bond amount of 9.5% by weight and a styrene block of 0.0% by weight.

The modified rubber was then analyzed. The rubber was 24.9% by weight of styrene bond, 15.4% by weight of styrene block, and 14 mol% of vinyl bond.

It was confirmed that the latter portion, other than the polymer partial structure R, and occupying 20% by weight, was tape type block copolymer B in which the amount of styrene bonds gradually increased to form terminal styrene blocks.

The molecular weight was 191,000 when the unmodified copolymer was measured by GPC. The molecular weight of the styrene block was 22,100 when the styrene block of the unmodified copolymer was analyzed by GPC.

The coupling rate and the modification rate of the modified rubber using the modifier were 61% by weight and 74% by weight, respectively.

Furthermore, the modified rubber had a Mooney viscosity (ML1 + 4, 100 ° C) of 72.

Modified rubber 2

The same one-step polymerization operation as in modified rubber 1 was carried out except that 16 g of tetrahydrofuran was added before the start of polymerization. From the monomer conversion measurements and the binding styrene analysis and the styrene block analysis during the polymerization shown in Table 2, the first half of the polymer, which occupies 70% by weight, constitutes a random copolymer R with 30.9% by weight of bound styrene and 0.0% by weight of styrene block. Confirmed.

From the analysis of the amount of styrene bonds and the styrene blocks after the end of the polymerization reaction, it was confirmed that the second half of the polymer, which occupies 30% by weight, was a tape-type end-styrene-block copolymer.

The details of the polymerization and the results of the analysis are shown in Table 1a and Table 3a, respectively.

Modified rubber 3

The atmosphere in a 10L autoclave fitted with a hot water jacket and a stirrer was sufficiently exchanged with nitrogen. Thereto was charged 4.5 kg of cyclohexane and 0.90 kg of 1,3-butadiene, each dehydrated with activated alumina, as a one-stage monomer. The contents were heated to 56 ° C. with stirring and 0.95 g of n-butyllithium (20% cyclohexane solution) was added to initiate the polymerization. The polymerization temperature reached 82 ° C. Thus, the polymerization of 1,3-butadiene to obtain the polymer R was terminated. Subsequently, polymerization was conducted to obtain polymer B by adding 0.10 kg of styrene as a two-stage monomer. The maximum polymerization temperature reached 89 ° C. After 2 minutes, 1.6 g of tetraglycidyl-1,3-bisaminomethylcyclohexane was added and the denaturation reaction was carried out for 8 minutes. Upon addition of the modifier, the conversion of styrene was 100.0 wt%. 10 ml of water / methanol were added as active-lithium disintegrant and mixed with the modified rubber polymerization solution thus obtained. Thereafter, 2 g of BHT was added thereto as a stabilizer and mixed. The mixture was solvent removed and dried using a drum dryer to give a solid modified rubber.

The analytical value of the modified rubber was 10.1 wt% of styrene bond, 9.5 wt% of styrene block, 13.5 mol% of vinyl bond, 79 wt% of coupling rate, and 86 wt% of copolymer modification rate.

The unmodified copolymer had a molecular weight of 122,000 and a molecular weight of styrene blocks of 9,500.

Furthermore, the modified rubber had a Mooney viscosity (ML1 + 4, 100 ° C) of 43.

Comparative rubber 1

A rubber was produced in the same manner as the modified rubber 1 except that no modifying agent was added at the end.

Comparison rubber 2

N-butyllithium was added in an amount of 2.1 g as a polymerization initiator, and the modification reaction was performed for 10 minutes by adding 6.0 g of tetraglycidyl-1,3-bisaminomethylcyclohexane after the completion of the polymerization. Then, rubber was manufactured in the same manner as in Modified Rubber 2. The resulting rubber was then completed in the same manner. However, the viscosity was so low that it was particularly difficult to finish. The modified rubber had a Mooney viscosity (ML1 + 4, 100 ° C) of 13.

Modified rubber 4

The polymerization operation was carried out in the same manner as in modified rubber 3 except that 1.2 g of N, N, N ', N'-tetramethylethylenediamine was added before the start of the polymerization.

The resulting rubber was then completed in the same manner.

Modified rubber 5

The atmosphere in a 10L autoclave fitted with a hot water jacket and a stirrer was sufficiently exchanged with nitrogen. It was filled with 4.5 kg of cyclohexane, 0.18 kg of styrene and 0.27 kg of 1,3-butadiene, each of which was treated with activated alumina as a one-stage monomer. The contents were heated to 57 ° C. with stirring, and 0.87 g of n-butyllithium (20 wt% cyclohexane solution) was added to initiate the polymerization. When the polymerization temperature reached 67 ° C., 1,3-butadiene began to be added to the polymerization system in a total amount of 0.15 kg at a rate of 0.03 kg per minute for 5 minutes. After completion of the addition, the polymerization temperature reached 81 ° C. Thus, the polymerization was terminated to obtain a random copolymer as polymer partial structure R. Subsequently, polymerization was performed to obtain polymer B by adding 0.22 kg of styrene and 0.18 kg of 1,3-butadiene as two-stage monomers. The maximum polymerization temperature reached 86 ° C. After 3 minutes, 4.0 g of tetraglycidyl-1,3-bisaminomethylcyclohexane was added and the denaturation reaction was carried out for 10 minutes. 10 ml of water / methanol were added as active-lithium decomposer and mixed with the modified rubber polymerization solution thus obtained. Thereafter, 2 g of BHT was added thereto as a stabilizer and mixed. The mixture was solvent removed and dried using a drum dryer to give a solid modified rubber.

The modified rubber was a tape-type end-styrene-block copolymer in which the amount of styrene bonds was 39.3% by weight, the amount of styrene blocks was 10.5% by weight, and the bound styrene gradually increased. Its Mooney viscosity (ML1 + 4, 100 ° C) was 62.

Modified rubber 6

The atmosphere in a 10L autoclave fitted with a hot water jacket and a stirrer was sufficiently exchanged with nitrogen. Thereto was charged 4.5 kg of cyclohexane and 0.88 kg of 1,3-butadiene, each treated with activated alumina, as a one-stage monomer. The contents were heated to 59 ° C. with stirring and 0.97 g of n-butyllithium (20 wt% cyclohexane solution) was added to initiate the polymerization. The polymerization temperature reached 82 ° C. Thus, the polymerization of 1,3-butadiene to obtain the polymer R was terminated.

Subsequently, polymerization was carried out continuously by adding 0.12 kg of styrene as a two-stage monomer. The polymerization temperature reached 89 ° C. Thus, polystyrene fragments were obtained as polymer B. One minute after the end of the polymerization, a 3.0 g mixture solution consisting of 50 wt% bisphenol A diglycidyl ether and 50 wt% bisphenol F diglycidyl ether was added and the denaturation reaction was carried out for 8 minutes. . 10 ml of water / methanol were added as active-lithium decomposer and mixed with the modified rubber polymerization solution thus obtained. Thereafter, 2 g of BHT was added thereto as a stabilizer and mixed. The mixture was solvent removed and dried using a drum dryer to give a solid modified rubber.

The analysis value of the modified rubber was 12.0 wt% of styrene bond, 11.6 wt% of styrene block, and 13.0 mol% of vinyl bond. Analysis by GPC showed that the unmodified copolymer had a molecular weight of 122,000 and the styrene block had a molecular weight of 10,100.

The modified rubber had a coupling ratio of 82% by weight and a modification rate of 88% by weight.

Furthermore, the modified rubber had a Mooney viscosity (ML1 + 4, 100 ° C) of 43.

Modified rubber 7

The same preparation method as for modified rubber 2 was carried out except for the following: A modification reaction was performed for 10 minutes by adding 4.7 g of tetraglycidyl-1,3-bisaminomethylcyclohexane, followed by 0.22 g of n-butyllithium was further added as an unreacted modifier epoxy treatment and reacted for 5 minutes, after which the reaction mixture was withdrawn from the autoclave and simultaneously mixed with 10 mL of water / methanol. Subsequently, the resultant rubber was completed in the same manner as the modified rubber 1.

From the measurements of monomer conversion, bound styrene and the like during the polymerization shown in Table 2, the following was confirmed. In the modified rubber, the first half of the polymer, which occupies about 70% by weight, had a random polymer partial structure R with a styrene bond of 30.8% by weight and a styrene block of 0.0% by weight, as in the case of modified rubber 2.

Comparison rubber 3

The same manufacturing method as in modified rubber 5 was carried out except that no modifying agent was added at the end.

Comparison rubber 4

24 g of tetrahydrofuran was added to the modified rubber 1 and polymerized. After completion of the polymerization, 4.5 g of tetraglycidyl-1,3-bisaminomethylcyclohexane was added to modify the rubber. Subsequently, the resultant rubber was completed in the same manner as the modified rubber 1.

The amount of styrene blocks in the obtained modified rubber was as small as 1.4 wt%. Moreover, as is apparent from the monomer conversion and styrene bond amounts shown in Table 2, the modified rubber was a copolymer in which most of the monomer units were randomly arranged.

Other analyzes are shown in Table 3b.

Comparison rubber 5

The atmosphere in a 10L autoclave fitted with a hot water jacket and a stirrer was sufficiently exchanged with nitrogen. It was filled with 4.5 kg of cyclohexane and 0.20 kg of styrene, each of which was treated with activated alumina, as a first stage monomer. The contents were heated to 57 ° C. with stirring and 0.92 g of n-butyllithium (20 wt% cyclohexane solution) was added to initiate the polymerization. The polymerization temperature reached 68 ° C. Thus, the one-step polymerization was completed.

The polymerization was then carried out continuously by adding 0.80 kg of 1,3-butadiene as a two stage monomer. The polymerization temperature reached 86 ° C. before the polymerization was completed. One minute after the end of the polymerization, a 2.6 g mixture solution consisting of 50% bisphenol A diglycidyl ether and 50% bisphenol F diglycidyl ether was added and the denaturation reaction was carried out for 8 minutes. 10 ml of water / methanol were added as active-lithium decomposer and mixed with the modified rubber polymerization solution thus obtained. Thereafter, 2 g of BHT was added thereto as a stabilizer and mixed. The mixture was solvent removed and dried using a drum dryer to give a solid modified rubber.

The analytical value of the modified rubber was 20.0% by weight of styrene bond, 19.5% by weight of styrene block, and 14.0 mol% of vinyl bond. Analysis by GPC showed that the modified rubber had a molecular weight of 224,000 and the molecular weight of the styrene block before modification was 17,100.

The modified rubber had a coupling ratio of 81 wt% and a modification rate of 88 wt%.

Moreover, the Mooney viscosity of the modified rubber could not be measured.

Various modified rubbers of the present invention and various comparative rubbers thus prepared were kneaded together with silica, silane coupling agents and other compounding components in the following manner to obtain modified rubber compositions of the present invention.

(Kneading method)

A 0.3L pressure kneader equipped with a temperature controller was used to mix silica, carbon black, silane coupling agent, naphthenic oil, zinc white, stearic acid, and the like together with the original rubber.

A two stage kneading method was used in which the one stage kneading period was 5 minutes and the maximum kneading temperature was adjusted to 161 ° C.

The compound obtained by one-step kneading was cooled to room temperature, kneaded again for three minutes, during which the maximum temperature was adjusted to 158 ° C. The compound obtained by two stage kneading was cooled to room temperature and then mixed with antioxidant, sulfur, and vulcanization accelerator through a 70 ° C. open roll mill.

Examples 1-7 and Comparative Examples 1-4

The modified rubbers 1 to 7 and comparative rubbers 1 to 4 of the present invention were kneaded and blended according to the following Formulation Example 1 to obtain the compositions of Examples 1 to 7 and Comparative Examples 1 to 4, respectively. In the following formulation, "parts" means "parts by weight".

<Formulation Example 1>

100.0 parts of rubber

Silica (Ultrasil VN3) 40 parts

2 parts of silane coupling agent (Si69)

Naphthene oil (Shellflex 371J) part 5

Zinc White Part 5

Stearic acid part 2

Antioxidant (SP) Part 1

Sulfur 1.7 parts

Vulcanization accelerator DM 1.5 parts

Vulcanization accelerator D 1.5 parts

--------------------------------------------------

Total 159.7 copies

The composition was molded, vulcanized at 160 ° C. for 20 minutes using a vulcanizer and measured for the following performance.

Comparative Example 5

Comparative Rubber 5 was used, which is a thermoplastic elastomer with two or more styrene blocks in the molecule. The rubber was blended according to the same formulation as in Example 1 to obtain a composition of Comparative Example 5. However, the composition has remarkably poor processability, is difficult to knead with a kneader, and cannot be processed into a roll. Therefore, this evaluation was omitted.

1) tensile strength

Tensile strength was measured by the tensile test method according to JIS-K6251.

2) torsional and temperature dependence of tanδ

The tan δ was measured at 0 ° C., 50 ° C., and 70 ° C. in a torsion manner at a frequency of 10 Hz using an ARES viscoelastic tester manufactured by Rheometric Ltd. Dependency was calculated using the following formula.

Torsional dependence is the value calculated from the measurement at 50 ° C using the following formula.

(10% tanδ- 0.1% tanδ) × 100 (%) / 0.1% tanδ

The temperature dependence is the value calculated using the following formula.

(3% tanδ (0 ℃) -3% tanδ (50 ℃) × 100 (%) / 3% tanδ (50 ℃)

3) compression set (c-set)

It measured by the compression set test method in accordance with JIS-K6301 under the conditions of 70 degreeC and 22 hours.

The properties of the vulcanizing composition are shown in Tables 4a and 4b.

Examples 8-10 and Comparative Examples 6 and 7

Moreover, the vulcanizability of the composition according to Formulation Example 2 below is shown in Table 5.

Note 1) Emulsion SBR 1502, Nippon Zeon Co., Ltd. Produce

Note 2) D-35, Asahi Chemical Industry Co., Ltd. Produce

Note 3) trade name, ULTRASIL VN3; Manufacture of Degusa AG

Note 4) Trade name, Seast KH; Tokai Carbon Co., Ltd. Produce

Note 5) silane coupling agent Si69, Degusa AG

Real name: Bis [3- (triethoxysilyl) propyl] tetrasulfide

The denaturant represented by the symbol ^* is a mixture of 50% by weight bisphenol A glycidyl ether represented by formula (2-a) and 50% by weight bisphenol F glycidyl ether represented by formula (2-b).

Note 6) (10% tanδ-0.1% tanδ) x 100 (%) / 0.1% tanδ at 50 ° C

Note 7) (3% tanδ (0 ℃)-3% tanδ (50 ℃) × 100 (%) / 3% tanδ (50 ℃)

Note 6) (10% tanδ-0.1% tanδ) x 100 (%) / 0.1% tanδ at 50 ° C

Note 7) (3% tanδ (0 ℃)-3% tanδ (50 ℃) × 100 (%) / 3% tanδ (50 ℃)

Note 6) (10% tanδ-0.1% tanδ) x 100 (%) / 0.1% tanδ at 50 ° C

Note 7) (3% tanδ (0 ℃)-3% tanδ (50 ℃) × 100 (%) / 3% tanδ (50 ℃)

The modified rubber of the present invention has particularly good affinity for silica and is suitable for use in various silica-containing compositions.

Moreover, the modified rubber composition containing the modified rubber of the present invention in a certain amount has good resistance to compression set (c-set) and good viscoelasticity, and as shown in Tables 4a, 4b and 5, the torsion of tanδ The dependence and temperature dependence are reduced.

When used for anti-vibration, the modified rubber composition of the present invention, which has such excellent properties, has little torsional and temperature dependence of tan δ, so that there is little change in performance depending on changing ambient conditions. Thus the composition is very useful.

Moreover, the modified rubber composition of the present invention has moderate hardness, excellent c-set and the like. Thus, it can be seen that the composition also has excellent properties in shoe products.

The modified rubber composition of the present invention having such excellent properties can advantageously also be used in other industrial products and the like.

Although the present invention has been described in detail with respect to specific embodiments thereof, it will be apparent to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope thereof.

The application is based on Japanese Patent Application (Japanese Patent Application No. 2001-038386), the contents of which are incorporated herein by reference and filed on February 15, 2001.

Claims (11)

The following general formula obtained by modifying the copolymer of (R-B) structure: (R-B) n-X [Wherein R represents a conjugated diene polymer or a vinylaromatic hydrocarbon / conjugated diene random copolymer having a vinyl aromatic hydrocarbon bond amount of 50% by weight or less; B represents a vinylaromatic hydrocarbon / conjugated diene copolymer or vinylaromatic hydrocarbon polymer block having a vinylaromatic hydrocarbon polymer block, R / B weight ratio ranges from 30/70 to 97/3; n is an integer of 1 or more; X represents a modified moiety of a compound having two or more epoxy groups per molecule] As a modified rubber containing a modified copolymer represented by Consisting of 5 to 60% by weight of the total amount of vinylaromatic hydrocarbons, 3 to 40% by weight of the vinylaromatic hydrocarbon polymer blocks and 80% or less by weight of the vinyl bonds in the conjugated diene moiety, measured by GPC, and modified with a modifier. A modified rubber having a main peak molecular weight of 100,000 to 1,500,000 of the molecules coupled by it. The modified rubber according to claim 1, wherein X is a modified moiety of a compound having at least two epoxy groups and one nitrogen atom per molecule. The modified rubber according to claim 1, wherein X is a modified residue of a glycidylamino compound. The molecular weight of the copolymer of the (RB) structure before modification is 30,000 to 500,000, the molecular weight of the vinylaromatic hydrocarbon polymer block is 5,000 to 50,000, the modification rate using a compound having two or more epoxy groups per molecule is 20 weight Modified rubber that is more than%. A process for producing the modified rubber of claim 1 comprising the following steps: Preparing a block copolymer of (R-B) structure comprising a vinylaromatic hydrocarbon and a conjugated diene by a solution polymerization method using an organolithium compound as an initiator; And modifying the copolymer by reacting the reactive end of the copolymer with a compound having two or more epoxy groups per molecule. The method of claim 5, wherein the compound having at least two epoxy groups per molecule is added at the end of the unmodified copolymer in an amount of 0.05 to 2 moles per mole of active lithium. The modified rubber composition containing 100 parts by weight of the original rubber containing the modified rubber of claim 1 and 5 to 150 parts by weight of silica. 8. The modification rate according to claim 7, wherein the copolymer of the (RB) structure before modification is 30,000 to 500,000, the vinylaromatic hydrocarbon polymer block has a molecular weight of 5,000 to 50,000, and the modification ratio is 20% by using a compound having two or more epoxy groups per molecule. Modified rubber composition that is at least%. 8. The modified rubber according to claim 7, wherein the original rubber contains 99 to 20% by weight of modified rubber and 1 to 80% by weight of at least one rubber selected from natural rubber, polybutadiene rubber, styrene / butadiene rubber and polyisoprene rubber. Composition. An anti-vibration rubber containing the modified rubber composition according to any one of claims 7 to 9. A shoe product containing the modified rubber composition according to any one of claims 7 to 9.