WO2003070797A1 - Conjugated diene rubber, oil-extended rubber and rubber composition - Google Patents

Abstract

A conjugated diene rubber which comprises 40 to 99.9 wt% of units of a conjugated diene monomer, 0 to 59.9 wt% of units of an aromatic vinyl monomer, and 0.1 to 20 wt% of units of a polar monomer and having a Mooney viscosity (M1) of 20 to 150 and which is produced by initiating the polymerization of a monomer mixture comprising at least part of the conjugated diene monomer to be polymerized and at least part of the aromatic vinyl monomer to be polymerized and containing the polar monomer to be polymerized in an amount of 0 to less than 30 wt%, then adding the rests of the conjugated diene monomer and the aromatic vinyl monomer to the system, and continuing the polymerization while adding the rest of the polar monomer and a molecular weight modifier to the reaction system at a stage wherein the Mooney viscosity of the polymer in the system falls within the range of 70 to 200 and is higher than M1 by at least five. This rubber is excellent in processability and can give crosslinked rubber articles excellent in tensile properties and the prevention of heat build-up.

Description

 Description Conjugated gen-based rubber, oil-extended rubber and rubber composition

 The present invention relates to a conjugated rubber, an oil-extended rubber and a rubber composition. More specifically, a conjugated gen-based rubber which is excellent in the surface shape of a sheet when a compound containing silica as a reinforcing agent is formed into a sheet by a roll, and which is excellent in tensile properties and low heat generation, The present invention relates to an oil-extended rubber containing an extension oil, and a rubber composition containing the rubber. Background art

 In recent years, the importance of resource saving and environmental measures has been emphasized, and the demand for lower fuel consumption of automobiles has become more and more strict.Car tires are required to contribute to lower fuel consumption by reducing rolling resistance. Have been.

 In order to reduce the rolling resistance of a tire, it is known to use a rubber composition obtained by compounding a conjugated gen-based rubber with a sili force instead of carbon black as a reinforcing agent. Such a rubber composition containing silica is excellent in low heat build-up as compared with a rubber composition containing carbon black, so that the rolling resistance of the tire can be reduced, but the abrasion resistance and tensile properties are inferior. In order to solve this problem, it has been proposed to use a gen-based rubber obtained by copolymerizing a monomer having an amino group.

For example, JP-A-64-222940 discloses a conjugated gen-based rubber obtained by copolymerizing an amino group-containing monomer by solution polymerization using an organic alkali metal or the like as a polymerization catalyst. Silica-containing rubber compositions with improved breaking strength and abrasion resistance have been disclosed. This publication also discloses a specific compounding example in which a styrene-butadiene copolymer rubber having a natural rubber rubber viscosity of about 50 is blended with the conjugated gen-based rubber. However, such a conjugated rubber is generally inferior in processability due to a narrow molecular weight distribution, and the rubber blend described above has a slight improvement in processability but a poor balance between low heat build-up and tensile properties. Rubber set with poor processability As for the product, the surface shape of the rubber composition formed into a resilient shape by a roll deteriorates, and it becomes difficult to form a green tire in the tire manufacturing process.

 Japanese Patent Application Laid-Open No. 1-101344 discloses that a tertiary amino group-containing monomer containing a conjugated gen-based rubber obtained by emulsifying and copolymerizing 1 to 20% by weight of a tertiary amino group is obtained. A silica-containing rubber composition having excellent properties and the like is disclosed. This publication also discloses a specific example of blending a styrene-butadiene copolymer rubber having a natural rubber rubber viscosity of about 50 with this conjugated diene rubber. However, rubber compositions containing such conjugated rubbers are inferior in processability, and the rubber blends exemplified above are insufficient in processability, and have a balance between low heat build-up and tensile properties. However, it is hard to say that it is good.

 Further, Japanese Patent Application Laid-Open No. 8-134272 discloses a conjugated rubber containing a tertiary amino group-containing monomer of less than 1% by weight and a silane coupling agent. A silica compounded rubber composition kneaded under conditions is disclosed. Such a rubber composition has excellent extrudability and excellent tensile properties and low heat build-up, but the surface shape of the rubber composition when formed into a sheet by a roll is not satisfactory. Did not. Disclosure of the invention

 SUMMARY OF THE INVENTION In view of the above-mentioned circumstances, an object of the present invention is to provide an excellent sheet surface shape when a compound containing silica as a reinforcing agent is formed into a sheet by a roll, and to have tensile properties and low heat build-up. It is an object of the present invention to provide a conjugated gen-based rubber excellent in water resistance, an oil-extended rubber obtained by blending the rubber with an extension oil, and a rubber composition containing the rubber.

The present inventors have conducted intensive studies in order to achieve the above object, and have found that when copolymerizing 1,3-butylene, styrene and an amino group-containing monomer, 1,3-butadiene and After the polymerization of styrene is started, the polymerization can be obtained by adding an amino group-containing monomer and a molecular weight modifier in a state where a polymer having a relatively high Mooney viscosity is present in the reaction system. By using a conjugated gen-based rubber, the surface shape of the sheet when a compound containing silica as a reinforcing agent is formed into a sheet with a roll, and excellent in tensile properties and low heat build-up That the compounded rubber composition can be obtained. Based on the findings and the findings, the present invention has been completed.

 Thus, according to the present invention, 40 to 99.9% by weight of a conjugated diene monomer unit, 0 to 59.9% by weight of an aromatic vinyl monomer unit, and 0.1% by weight of a polar group-containing monomer unit. 1 to

A conjugated rubber comprising 20% by weight and having a viscosity (Ml) of 20 to 150, wherein at least a part of a conjugated monomer used for polymerization and an aromatic vinyl Contains at least a part of the monomer, does not contain a polar group-containing monomer, or

The polymerization of the monomer mixture containing less than 30% by weight is started, and the addition of the remaining conjugated diene monomer and the remaining aromatic vinyl monomer is completed by the time the polymerization is stopped. The remainder of the group-containing monomer and the molecular weight modifier are combined with the viscosity of the polymer in the reaction system.

(M 2) is in the range of 70 to 200, and is added while it is higher than M 1 by 5 or more. . Further, according to the present invention, there is provided an oil-extended rubber comprising the conjugated rubber and an extending oil.

 Further, according to the present invention, there is provided a rubber composition containing the conjugated rubber. BEST MODE FOR CARRYING OUT THE INVENTION

 Hereinafter, the present invention will be described in detail.

The conjugated diene rubber of the present invention has a conjugated diene monomer unit of 40 to 99.9% by weight, an aromatic vinyl monomer unit of 0 to 59.9% by weight, and a polar group-containing monomer unit of 0. It is a conjugated rubber composed of 1 to 20% by weight and having a Mooney viscosity (Ml) of 20 to 150, and is a rubber obtained by a specific polymerization method. That is, at the time of producing the syngeneic rubber of the present invention, at least a part of the conjugated gen monomer used for the polymerization is contained, and when an aromatic vinyl monomer is used, at least a part thereof is used. The polymerization is started by using a monomer mixture containing no polar group-containing monomer or containing less than 30% by weight of the monomer as the initially charged monomer mixture. Thereafter, the addition of the remaining conjugated diene monomer and the remaining aromatic vinyl monomer is completed by the time the polymerization is stopped. Further, the remaining monomer of the polar group-containing monomer and the molecular weight modifier are mixed with each other in such a manner that the Mooney viscosity (M 2) of the polymer in the reaction system is in the range of 70 to 200, and The polymerization is continued by adding while the viscosity is at least 5 times higher than the conjugated rubber's viscosity (Ml).

The conjugated diene rubber is composed of 40 to 99.9% by weight, preferably 50 to 89.8% by weight, more preferably 55 to 9.7% by weight, conjugated diene monomer unit, and aromatic vinyl monomer unit. Monomer unit 0-5.99% by weight, preferably 10-49.8% by weight, more preferably 20-44.7% by weight, and a polar group-containing monomer unit 0.1-1. 20% by weight, preferably 0.2 to 10% by weight, more preferably 0.3 to 5% by weight, and its viscosity (ML _{1 + 4} , 100 ° C: J1 J is sometimes abbreviated as 20 to 250, preferably 50 to 140, more preferably 80 to 130.

 When the conjugated gen monomer unit in the conjugated gen-based rubber is small, the heat generation is poor.

 An aromatic vinyl monomer unit is preferably included because it contributes to improvement in tensile properties. However, if the amount is excessive, the tensile properties are inferior.

 If the amount of the polar group-containing monomer unit is small, low heat build-up and tensile properties are inferior. On the other hand, if the amount is large, the surface shape of the silica-containing rubber composition formed into a sheet by a roll becomes poor. If the Mooney viscosity is low, low heat build-up and tensile properties are inferior.On the contrary, if it is high, the surface shape of the silica-containing rubber composition molded into a sheet with a roll deteriorates, or the viscosity of the compound becomes too high to process. It will be difficult.

 The conjugated diene rubber contains other monomer units other than the conjugated diene monomer unit, the aromatic vinyl monomer unit and the polar group-containing monomer unit within a range that does not essentially impair the effects of the present invention. May be included. The amount is preferably at most 20% by weight, more preferably at most 10% by weight. If the amount is too large, the physical balance of the crosslinked rubber tends to deteriorate.

 Examples of the conjugated diene monomer include 1,3-butadiene, 2-methyl-3-butadiene, 2,3-dimethyl-1,3-butadiene, 2-chloro-1,3-butadiene, and 1,3-pentadiene. Is mentioned. Of these, 1,3-butadiene is preferred. These can be used alone or in combination of two or more.

As the aromatic vinyl monomer, an aromatic vinyl compound having no polar group is used. Examples include styrene, α-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 2,4-diisopropylstyrene, 2,4-dimethylstyrene, and 4-t-butylstyrene. , 5-t-butyl-2-methylstyrene, monochlorostyrene, dichlorostyrene, monoflurostyrene, and the like. Of these, styrene is preferred. These can be used alone or in combination of two or more.

 The polar group-containing monomer is a polymerizable monomer having at least one polar group in one molecule. The polar group is not particularly limited as long as it can react with the silica surface. Examples thereof include an amino group, an epoxy group, an alkoxysilyl group, an aryloxyxyl group, a hydroxyl group, a sulfido group, and a disulfide. Group, a sulfonyl group, a sulfinyl group, a thiol group, an imino group, and an imide group. Among these, an amino group, an epoxy group, an alkoxysilyl group, an aryloxyl silyl group, and a hydroxyl group are preferred, an amino group, an epoxy group, an alkoxysilyl group, and an aryloxyl silyl group are more preferred, and the epoxy group and the amino group are more preferred. Particularly preferred. The amino group-containing monomer is a polymerizable monomer having at least one amino group selected from primary, secondary and tertiary amino groups in one molecule, and among them, tertiary amino group Are preferred.

 Examples of the primary amino group-containing monomer include P-aminostyrene, aminomethyl acrylate, aminoethyl acrylate, aminopropyl acrylate, aminobutyl acrylate, aminomethyl methacrylate, aminoethyl methacrylate, and aminopropyl. Methacrylate, aminobutyl methacrylate, and the like.

 Examples of the secondary amino group-containing monomer include anilinostyrenes disclosed in JP-A-61-135355; N-methylacrylamide, N-ethylacrylamide, and N-methylmetha. N-monosubstituted acrylamides and N-monosubstituted methacrylamides such as acrylamide, N-ethylmethacrylamide, N-methylolacrylamide, N- (4-anilinophenyl) methacrylamide, and the like. .

Examples of the tertiary amino group-containing monomers include, for example, N, N-disubstituted aminoalkyl Crylate, N, N-disubstituted aminoalkyl acrylamide, N, N-disubstituted aminoalkyl methacrylate, N, N-disubstituted aminoalkyl methacrylamide, N, N-disubstituted aminoalkyl aromatic vinyl compound and pyridyl group And the like.

 Examples of the N, N-disubstituted aminoalkyl (meth) acrylate include N, N-dimethylaminomethyl (meth) acrylate, N, N—dimethylaminoethyl (meth) acrylate, N, N— Dimethylaminopropyl (meth) acrylate, N, N—Dimethylaminobutyl (meth) acrylate, N, N—Jethylaminoethyl (meth) acrylate, N, N—Jetylaminopropyl ) Acrylate, N, N—Jethylaminobutyl (meth) acrylate, N-methyl-N-ethylaminoethyl (meth) acrylate, N, N—Dipropylaminoethyl (meth) acrylate, N, N-dibutylamino Ethyl (meth) acrylate, N, N-dibutylaminopropyl (meth) acrylate, N, N-dibutylaminobutyl Meth) Akurire Bok, N, N - the di Kishiruamino Echiru (meth) Akurire Bok, N, N - di old Chi le aminoethyl (meth) § click relay Bok and the like. Of these, N, N-dimethylaminoethyl (meth) acrylate, N, N-getylaminoethyl (meth) acrylate and N, N-dipropylaminoethyl (meth) acrylate are preferred.

 Examples of N, N-disubstituted aminoalkyl (meth) acrylamide include N, N-dimethylaminomethyl (meth) acrylamide, N, N-dimethylaminoethyl (meth) acrylamide, N, N-dimethylamino Propyl (meth) acrylamide, N, N-dimethylaminobutyl (meth) acrylamide, N, N-Diethylaminoethyl (meth) acrylamide, N, N—Getylaminopropyl

(Meth) acrylamide, N, N—Gethylaminobutyl (meth) acrylamide, N-methyl-N-ethylaminoethyl (meth) acrylamide, N, N—Dipropylaminoethyl (meth) acrylamide, N, N —Dibutylaminoethyl

(Meth) acrylamide, N, N-dibutylaminopropyl (meth) acrylamide, N, N—dibutylaminobutyl (meth) acrylamide, N, N—dihexylaminoethyl (meth) acrylamide, N, N— Dihexylaminopropyl (Meth) acrylamide, N, N-dimethyloctylaminopropyl (meth) acrylamide and the like. Of these, N, N-dimethylaminopropyl (meth) acrylamide and N, N-getylaminopropyl (meth) acrylamide are preferred.

 Examples of the N, N-disubstituted aminoalkyl aromatic vinyl compound include N, N-dimethylaminoethylstyrene, N, N-dimethylethylethylstyrene, N, N-dipropylaminoethylstyrene, N, N— And diethyl octylaminoethylstyrene.

 Examples of the polymerizable monomer having a pyridyl group include 2-vinylpyridine, 4-vinylpyridine, 5-methyl-2-vinylpyridine, 5-ethyl-2-vinylpyridine and the like. Among these, 2-vinylpyridine and 4-vinylpyridine are preferred.

 These amino group-containing monomers can be used alone or in combination of two or more.

 The epoxy group-containing monomer is a polymerizable monomer having at least one epoxy group in one molecule.

 Epoxy group-containing monomers include, for example, glycidyl acrylate, 3,4-epoxybutyl acrylate, 3,4 xycyclohexyl acrylate, N-glycidyl acrylamide, glycidyl methacrylate, 3,4-epoxy heptyl Methacrylate, 3,4-year-old xycyclohexyl methacrylate, N-glycidyl methacrylamide, vinyldaricidyl ether, arylglycidyl ether, 2-methylarylglycidyl ether, 3,4-epoxy-1-butene 1,3-epoxy-1-methyl-1—butene, 3,4-epoxy—Ί—pentene, 3,4-epoxy—3—methyl-1-pentene, 5,6—epoxy—1-hexene And vinylcyclohexene monooxide, styrene-p-glycidyl ether and the like. Of these, glycidyl acrylate and glycidyl methacrylate are preferred.

These epoxy group-containing monomers can be used alone or in combination of two or more. The alkoxysilyl group-containing monomer is a polymerizable monomer having at least one alkoxysilyl group in one molecule.

 Examples of the alkoxysilyl group-containing monomer include (meth) acryloxymethyltrimethoxysilane, (meth) acryloxymethyltriethoxysilane, / 3- (meth) acryloxyshethyltrimethoxysilane, 8) (Meth) acryloxysilyl triethoxysilane, α (meth) acryloxypropyl trimethoxysilane, α (meth) acryloxypropyl triethoxysilane, α (meth) acryl Roxypropyltripropoxysilane, α- (meth) acryloxypropyltributoxysilane, T- (meth) acryloxypropylmethyldimethoxysilane, r- (meth) acryloxypropylethyldimethoxysilane, r ― (Meth) acryloxypropylhexyldimethoxysilane, / 3-acryloxyshethyl Trimethylene Bok Kishishiran, r- (J8- § chestnut Loki Chez chill old alkoxy) propyl trimethinecyanine Bok Kishishiran, etc. § chromatography (§ over methacryloxypropyl O carboxymethyl) propyl Bok Increment Bok Kishishiran the like. Among these, τ- (meth) acryloxypropyltriethoxysilane, a (meth) acryloxypropyltripropoxysilane, a-1 (meth) acryloxypropyltriethoxysilane, τ— (β- Propyloxytripropyl silane, τ- (α-methacryloxypropyl oxy) propyltrioxysilane is preferred, and τ- (meth) acryloxypropyltripropoxysilane, α- (meth) acryloxy Propyl tributoxysilane is particularly preferred.

 These alkoxysilyl group-containing monomers can be used alone or in combination of two or more.

 The aryl-containing xylyl group-containing monomer is a polymerizable monomer having at least one aryl-containing xylyl group in one molecule.

Examples of the aryl-containing xylsilyl group-containing monomer include, for example, (meth) acryloxymethyl triphenyl,) 8- (meth) acryloxyshethyl triphenyl, Ύ- (meth) acryloxypropyl triphenyl Enoxysilane, acryl (meth) acryloxypropylmethyldiphenoxysilane, acryl (meth) acryloxypropylethyldiphenoxysilane, acryl (meth) acryloxypropylhexyldiphen Noxylsilane, jS-acryloxyshethyl xymethyltriphenoxysilane, τ- () 8-acryloxyshethyloxy) propyl Trifrhenoxysilane, τ— (T-methacryloxypropyl propyl) propyl Triphenyloxysilane and the like can be mentioned. Of these, preferred are (meth) acryloxypropyltriphenoxysilane and (meth) acryloxypropylmethyldiphenoxysilane.

 These aryl-containing xylsilyl group-containing monomers can be used alone or in combination of two or more.

 The hydroxyl group-containing monomer is a polymerizable monomer having at least one primary, secondary or tertiary hydroxyl group in one molecule.

Examples of the hydroxyl group-containing monomer include hydroxymethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and 3-hydroxypropyl (meth) acrylate. 2-hydroxypropyl (meth) acrylate, 3-phenoxy-12-hydroxypropyl (meth) acrylate, glycerol mono (meth) acrylate, hydroxybutyl (meth) acrylate, 2- Chloro-3-hydroxyl mouth pill (meth) acrylate, hydroxyhexyl (meth) acrylate, hidden mouth octyl (meth) acrylate, hydroxymethyl (meth) acrylamide, 2-hydroxypropyl (meth) acrylic Amide, 3-hydroxypropyl (meth) Acrylamide, di (ethylene glycol) itacone, g (propylene glycol) itacone, bis (2-hydroxypropyl) itacone, bis (2-hydroxyethyl) itacone, bis (2 —Hydroxyethyl) fumarate, bis (2-hydroxyethyl) maleate, 2-hydroxyethyl vinyl ether, hydroxymethyl vinyl ketone, and aryl alcohol. Among these, hydroxymethyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 3-hydroxypropyl acrylate, 3-phenoxy-12-hydroxypropyl acrylate, glycerol monoacrylate, hydroxybutyl Acrylate, hydroxyhexyl acrylate, hydroxy octyl acrylate, 2-hydroxy Cypropylacrylamide, 3-hydroxypropylacrylamide, hydroxymethyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 3-hydroxypropyl methacrylate, 3-phenoxy-12-hydroxypropyl methacrylate, glycerol Monomethacrylate, hydroxybutyl methacrylate, hydroxyhexyl methacrylate, hydroxyoctyl methacrylate, 2-hydroxypropyl methacrylamide, 3-hydroxypropyl methacrylamide and the like are preferred. The other monomer other than the conjugated gen, the aromatic vinyl monomer and the polar group-containing monomer is not particularly limited as long as it can be copolymerized with the conjugated gen or the like. Methyl, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, methyl propyl methacrylate, propyl methacrylate, 2-ethylhexyl methacrylate, Ethylenically unsaturated carboxylic acid alkyl ester monomers such as dibutyl maleate, getyl fumarate and dibutyl itaconate; ethylenically unsaturated such as acrylic acid, methacrylic acid, maleic acid, fumaric acid, monoethyl maleate and monobutyl fumarate Carboxylic acid monomer; acrylonitrile, methacrylonitrile Ethylenically unsaturated double Bok Lil monomers such; ethylene, a- old Refuin such as propylene, vinyl chloride, and vinyl acetate.

 In the production of the conjugated rubber of the present invention, at least a part of the conjugated monomer used for the polymerization is contained, and when an aromatic vinyl monomer is used, at least a part thereof is contained. The polymerization is started by using a monomer mixture containing no polar group-containing monomer or containing less than 30% by weight thereof as the initially charged monomer mixture. Thereafter, the addition of the remainder of the conjugated diene monomer and the remainder of the aromatic vinyl monomer is completed by the time the polymerization is stopped. In addition, the remainder of the polar group-containing monomer and the molecular weight modifier are mixed with each other when the Mooney viscosity (M 2) of the polymer in the reaction system is in the range of 70 to 200, and Continue the polymerization by adding while the viscosity is higher than 5 times the rubber viscosity (Ml) of the rubber.

The monomer composition used for the polymerization may be appropriately determined so that the composition of the conjugated rubber is within a predetermined range. However, when starting the polymerization, the monomer mixture contains at least a part of the conjugated gen monomer used in the polymerization, and further contains at least a part of the aromatic vinyl monomer when the aromatic vinyl monomer is used. It is essential that no polar group-containing monomer be contained or less than 30% by weight thereof.

 The amount of the conjugated diene monomer used at the start of the polymerization is preferably 80% by weight or more, more preferably 90% by weight or more, and particularly preferably the total amount of the conjugated dimer used in the polymerization. is there.

 When an aromatic vinyl monomer is used, the amount used at the start of the polymerization is preferably at least 80% by weight, more preferably at least 90% by weight, based on the amount of the aromatic vinyl monomer used in the polymerization. Particularly preferred is the total amount.

 The amount of the polar group-containing monomer used at the start of the polymerization is preferably less than 25% by weight, more preferably less than 23% by weight, particularly preferably 0% by weight of the polar group-containing monomer used for the polymerization. Or less than 20% by weight.

 If the amounts of the conjugated diene monomer and the aromatic vinyl monomer in the monomer mixture at the start of the polymerization are too small, the surface shape of the silica-containing rubber composition molded into a sheet with a roll may deteriorate. The viscosity of the compound tends to be too high.

 Also, when the amount of the polar group-containing monomer in the monomer mixture at the start of polymerization is large, the surface shape of the silica-containing rubber composition formed into a sheet by a roll is deteriorated, and the viscosity of the compound is reduced. It becomes too high and difficult to process.

 If the amount of the conjugated diene monomer and the aromatic vinyl monomer in the monomer mixture at the start of the polymerization is not the total amount of the conjugated diene monomer and the aromatic vinyl monomer used in the polymerization, the remaining The conjugated diene monomer and the aromatic vinyl monomer may be added to the polymerization reaction system before the termination of the polymerization. The method of addition is not particularly limited, and a method of batch addition, divided addition, or continuous addition can be employed. The timing of the addition is not particularly limited as long as it is before the termination of the polymerization, but it is preferable to add the polymer at a polymerization conversion of less than 65% by weight in the polymerization reaction system, and it is more preferable to add it at less than 60% by weight. It is good.

After the initiation of the polymerization, the remainder of the polar group-containing monomer and the molecular weight modifier were added while the polymer viscosity (M 2) of the polymer in the reaction system was in the range of 70 to 200. Then polymerization It is essential to continue. M2 at the time of addition preferably ranges from 80 to 150, more preferably from 90 to 140.

 If the Mooney viscosity of the polymer present in the polymerization reaction system is low, the low heat build-up and tensile properties are inferior, and if it is high, the surface shape of the silica-containing rubber composition molded into a sheet with rolls deteriorates. (4) The viscosity of the compound becomes too high, making processing difficult.

 If the molecular weight modifier is not added here, the final viscosity of the conjugated gen-based rubber increases, and the surface shape of the silica-containing rubber composition molded into a sheet with a roll deteriorates. Or the viscosity of the compound becomes too high, making processing difficult. The amount of the molecular weight modifier added depends on the type of the molecular weight modifier, but M1 is in the range of 20 to 150 and the difference between M2 and M1 (M2-M1) is 5 or more. It is advisable to adjust as appropriate.

 It is preferable that the timing of addition of the remainder of the polar group-containing monomer used in the polymerization and the molecular weight modifier is substantially the same, but the addition timing is shifted so long as the effects of the present invention are not essentially impaired. It may be added. As the addition method, a method of adding all at once is preferable, but a method of adding in portions or adding continuously may be adopted.

 Furthermore, it is essential that M 1 is at least 5 lower than M 2, [^ 1 1 is more preferably 8-50 lower than 1 ^ 2, and M 1 is 10-45 lower than M 2 Is particularly preferred. If this difference is small, the surface shape of the rubber compounded rubber composition formed into a sheet by a roll is deteriorated, and the viscosity of the compounded compound becomes too high, making processing difficult.

 When the remainder of the polar group-containing monomer is added, the amount of the polymer formed in the reaction system is preferably 20 to 80% by weight, more preferably 20 to 80% by weight of the total amount of the conjugated rubber obtained by polymerization. It is in the range from 30 to 75% by weight, particularly preferably from 40 to 70% by weight. When the amount of the produced polymer is in this range, the balance between the processability of the silica-containing rubber composition and the tensile properties and low heat build-up is excellent.

 The polymerization method that can be employed in the present invention is not particularly limited, and examples thereof include an emulsion polymerization method, a solution polymerization method, and a bulk polymerization method. Among them, the emulsion polymerization method can be preferably employed because the heat of reaction during the polymerization reaction is easily removed and the productivity is excellent.

As the emulsion polymerization method, an ordinary emulsion polymerization method may be used.For example, a predetermined amount of the above-mentioned monomer is emulsified and dispersed in an aqueous medium in the presence of an emulsifier, and the emulsification polymerization is carried out with a polymerization initiator. There is a method of combining. The amount of each monomer used is appropriately selected such that the amount of each monomer unit in the polymer becomes a desired content.

 As the emulsifier, for example, a long-chain fatty acid salt having 10 or more carbon atoms and a phosphate or rosinate are used. Specific examples thereof include potassium sulfate and lauric acid, myristic acid, palmitic acid, oleic acid, stearic acid, and other fatty acid salts or sodium salts.

 The amount of the emulsifier to be used is preferably 0.5 to 10 parts by weight, more preferably 1 to 8 parts by weight, based on 100 parts by weight of all the monomers.

 Examples of the polymerization initiator include persulfates such as ammonium persulfate and potassium persulfate; a combination of ammonium persulfate and ferric sulfate; a combination of an organic peroxide and ferric sulfate; And a redox initiator such as a combination of hydrogen peroxide and ferric sulfate;

 The amount of the polymerization initiator to be used is preferably 0.01 to 5 parts by weight, more preferably 0.05 to 3 parts by weight, based on 100 parts by weight of all the monomers.

 A molecular weight modifier is used to control the polymer viscosity. Examples of the molecular weight regulator include mercaptans such as t-dodecylmercaptan and n-dodecylmercaptan, carbon tetrachloride, thiocyanic glycolic acid, diterpenes, tapino-lenes, and alterpinenes. . Among them, mercaptans are preferred, and t-dodecyl mercaptan is more preferred, and can be used.

 The amount of the molecular weight modifier to be used is not particularly limited, but is usually 0.01 to 5 parts by weight, preferably 0.02 to 1 part by weight, more preferably 100 parts by weight based on 100 parts by weight of all monomers. Is from 0.05 to 0.5 parts by weight.

 The temperature of the emulsion polymerization can be appropriately selected depending on the type of the polymerization initiator to be used, but is usually 0 to 100, preferably 0 to 60 ° C. The polymerization mode may be any of continuous polymerization, batch polymerization and the like.

The polymerization conversion at the time of stopping the polymerization reaction is preferably 85% by weight or less, more preferably 50 to 80% by weight, from the viewpoint of preventing gelation of the polymer. . Usually, the polymerization reaction is stopped by adding a polymerization terminator to the polymerization system when a predetermined polymerization conversion rate is reached. As the polymerization terminator, for example, Amine compounds such as tylhydroxylamine and hydroxylamine; quinone compounds such as hydroquinone and benzoquinone; sodium nitrite, sodium hydroxide, and the like.

 After termination of the polymerization reaction, an antioxidant may be added, if necessary.

 After the termination of the polymerization reaction, unreacted monomers are removed from the obtained polymer latex, if necessary, and then the polymer can be solidified and recovered as a column. Salts such as sodium chloride, calcium chloride, and potassium chloride are used as the coagulant.Additionally, acids such as hydrochloric acid and sulfuric acid are added as necessary to adjust the pH of the coagulation system to a predetermined value. Can be coagulated. The collected crumb is washed, dehydrated, and dried with a band drier to obtain a desired conjugated gen-based rubber. If desired, at the time of coagulation, a polymer latex and an extending oil that has been made into an emulsified dispersion can be mixed and recovered as an oil-extended rubber.

 The conjugated gen-based rubber having M1 of 80 or more is preferably recovered as an oil-extended rubber because it has excellent dispersibility of the reinforcing agent and excellent balance of cross-linking properties. As the extender oil used for recovery as an oil extension rubber, those commonly used in the rubber industry can be used, for example, paraffin extender oil, aromatic extender oil, naphthenic extender oil, etc. .

 The pour point of the extender oil is preferably from 150 to 150 ° C, more preferably from -10 to 130 ° C. Within this range, it is easy to stretch and is excellent in balance between wear resistance and low heat generation. The aroma carbon content (CA%) of the extended oil by Kurz analysis is preferably 2% or more, more preferably 20% or more, and the paraffin carbon content (CP%) is preferably 70% or less, More preferably, it is 55%. If the ％% is too small or the CP% is too large, the tensile properties and wear resistance will be insufficient. The polycyclic aromatic content of the extender oil is preferably less than 3%. This content is measured by the method of IP346 (the inspection method of THIINSTITUTTEPETOLEM in the UK).

The compounding amount of the extender oil is preferably 5 to 100 parts by weight, more preferably 10 to 80 parts by weight, and particularly preferably 20 to 60 parts by weight with respect to 100 parts by weight of the conjugated rubber. Parts. When the blending amount of the extender oil is within this range, the viscosity of the blended compound containing silica is appropriate, and the balance between the tensile properties and the low heat generation is excellent.

 The rubber composition of the present invention contains the conjugated rubber or the oil-extended rubber comprising the conjugated rubber and an extension oil.

 The rubber composition of the present invention preferably contains at least one selected from silica and carbon black as a reinforcing agent, and particularly preferably contains silica as an essential component. As a reinforcing agent, a carbon-silica dual phase filler in which silica is supported on the surface of carbon black may be used.

 Examples of the silica include dry-type white carbon, wet-type white carbon, colloidal silica, and precipitated silica disclosed in JP-A-62-262838. Among these, a wet-process white carbon containing hydrous carboxylic acid as a main component is particularly preferable. These silicas can be used alone or in combination of two or more.

Although the specific surface area of silica is not particularly limited, it is preferably 50 to 400 mV g, more preferably 100 to 220 m ² / g, and particularly preferably 120 to 400 in terms of nitrogen adsorption specific surface area (BET method). 1 90 m ² / g. When the specific surface area of the silica is within this range, the balance between tensile properties and low heat build-up is excellent. The nitrogen adsorption specific surface area is a value measured by the BET method according to ASTMD303 7-81.

 As the carbon black, for example, furnace black, acetylene black, thermal black, channel black, graphite, and the like can be used. Among these, furnace black is particularly preferable, and specific examples thereof include SAF, ISAF, ISAF-HS, ISAF-LS, IISAF-HS, HAF, HAF-HS, HA F— Grades such as LS and FEF. These carbon blacks can be used alone or in combination of two or more.

The specific surface area of carbon black is not particularly limited, a nitrogen absorption specific surface area (N ₂ SA), preferably more preferably 5~20 Om ^ g 50 m~1 50 m 2 / g, particularly preferably 80 to 130 m ² / g. When the nitrogen adsorption specific surface area is in this range, the tensile properties are more excellent.

 The DBP adsorption amount of bonbon black is also not particularly limited, but is preferably 5 to 300 mI / 100 g, more preferably 50 to 200 ml "100 g, and particularly preferably. Is 80 to 16 0171 110 g When the DBP adsorption amount is within this range, the tensile properties are more excellent.

Furthermore, as carbon black, the specific surface area of adsorption (CTAB) of cetyl trimethylammonium bromide disclosed in Japanese Patent Application Laid-Open No. Hei 5-23090 is 110 to 17 Om ^2. g and DBP (24 M4 DBP) after repeated compression at 24,000 psi pressure four times.High structure with oil absorption of 110 g to 130 g. By using one carbon black, the wear resistance can be improved.

 The compounding amount of the reinforcing agent is preferably 100 to 200 parts by weight, more preferably 20 to 150 parts by weight, and particularly preferably 30 to 120 parts by weight, based on 100 parts by weight of the rubber component. Parts by weight. When both silica and carbon black are used in combination as a reinforcing agent, the mixing ratio is preferably silica: carbon black by weight, preferably 10:90 to 99: 9.

1, more preferably 30:70 to 95: 5, particularly preferably 50:50 to 90: 5.

It is 10

 When silica is contained as a reinforcing agent in the rubber composition of the present invention, it is preferable to add a silane coupling agent for the purpose of further improving tensile properties and low heat build-up.

Examples of the silane coupling agent include vinyltriethoxysilane, 8- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, and N— (i8-aminoethyl) -1-aminopropyltrimethoxysilane. , Bis (3- (triethoxysilyl) propyl) tetrasulfide, bis (3- (triethoxysilyl) propyl) disulfide, etc., and those described in JP-A-6-248116. Tetrasulfides, such as trimethoxysilylpropyl dimethylthiocapillamyl trisulfide and τ-trimethoxysilylpropyl benzothiazyl ditrasulfide. Since silane can be avoided during kneading, silane The coupling agent is preferably one having four or less sulfur contained in one molecule. These silane coupling agents can be used alone or in combination of two or more.

 The amount of the silane coupling agent is preferably 0.1 to 30 parts by weight, more preferably 1 to 20 parts by weight, and particularly preferably 2 to 10 parts by weight, based on 100 parts by weight of silica. is there.

 The rubber composition of the present invention may contain other rubbers other than the conjugated gen-based rubber of the present invention as long as the effects of the present invention are not substantially impaired. Other rubbers include, for example, natural rubber, octacis-polyisoprene rubber, high-cis-polybutadiene rubber, acrylonitrile-butadiene copolymer rubber, butyl rubber, ethylene-propylene-copolymer rubber, and the like.

 The rubber composition of the present invention contains, in addition to the above components, compounding agents such as a crosslinking agent, a crosslinking accelerator, a crosslinking activator, an antioxidant, an activator, a plasticizer, a lubricant, and a filler according to a conventional method. A necessary amount can be contained.

 Examples of the crosslinking agent include sulfur such as powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, and highly dispersible sulfur; sulfur halides such as sulfur monochloride and sulfur dichloride; dicumyl peroxy oxide; Organic peroxides such as one-year-old oxide; p-quinone-diamine, ρ, ρ'-dibenzoylquinone-dioxime and other quinone-diamine; triethylenetetramine; hexamethylenediamine; Organic polyamine compounds such as 4,4'-methylenebis-1-o-chloroaniline; alkylphenol resins having a methyl alcohol group; and the like. Of these, sulfur is preferred, and powdered sulfur is particularly preferred. These crosslinking agents are used alone or in combination of two or more. The amount of the crosslinking agent to be added is preferably 0.3 to 10 parts by weight, more preferably 0.5 to 5 parts by weight, based on 100 parts by weight of the rubber component.

Crosslinking accelerators include Ν-cyclohexyl-2-benzothiazolesulfenamide, Ν-t-butyl-2-benzothiazolesulfenamide, N-sulfuroxyethylene-12-benzothiazolsulfenamide, N —Alkoxyethylene-1-2-benzothiazolesulfenamide, Ν, Ν'-diisopropyl-12-benzonitchi Sulfenamide-based cross-linking accelerators such as azolesulfenamide; guanidine-based cross-linking accelerators such as diphenyldananidine, diorthotriguanidine, and o-tolylbiguanidine; Thiazole crosslinking accelerators such as 2-mercaptobenzothiazole, dibenzothiazyldisulfide, and 2-mercaptobenzothiazole zinc salt; thiurams such as tetramethylthiurammonosulfide and tetramethylthiuram disulfide; Crosslinking accelerators such as dimethyldithiocyanate, sodium rubamate dimethyldithiate, zinc dirubetinate, etc .; diluents such as sodium rubamate; sodium isopropylxanthrate, zinc isopropylxanthate, and butylxanthogen Xanthogens such as zinc acid System crosslinking accelerator; include crosslinking accelerators such as. These crosslinking accelerators may be used alone or in combination of two or more, but those containing a sulfenamide-based crosslinking accelerator are preferred. The compounding amount of the crosslinking accelerator is preferably from 0.3 to 10 parts by weight, more preferably from 0.5 to 5 parts by weight, based on 100 parts by weight of the rubber component.

 As the cross-linking activator, for example, higher fatty acids such as stearic acid and zinc oxide can be used. As zinc oxide, those having a high surface activity and a particle size of 5 tm or less are preferable. Specific examples of particularly preferred zinc oxide have a particle size of 0.05 to 0.5.

 Activated zinc white and 0.3-1 x m zinc white. Zinc oxide may be surface-treated with an amine-based dispersant or wetting agent. These crosslinking activators can be used alone or in combination of two or more. The mixing ratio of the crosslinking activator is appropriately selected depending on the type of the crosslinking activator. The blending amount of the higher fatty acid is preferably from 0.3 to 10 parts by weight, more preferably from 0.5 to 5 parts by weight, based on 100 parts by weight of the rubber component. The amount of zinc oxide is preferably from 0.1 to 5 parts by weight, more preferably from 0.5 to 2 parts by weight, based on 100 parts by weight of the rubber component.

Further, examples of the compounding agent include an activator such as diethylene glycol, polyethylene glycol and silicone oil; a filler such as calcium carbonate, talc, clay and aluminum hydroxide; and a wax. The rubber composition containing a reinforcing agent can be obtained by kneading the components according to a conventional method. For example, after kneading a compounding agent excluding a crosslinking agent and a crosslinking accelerator, a reinforcing agent, and a rubber component, a crosslinking agent and a crosslinking accelerator are added to the kneaded product, followed by kneading to obtain a rubber composition. The kneading temperature of the compounding agent excluding the crosslinking agent and the crosslinking accelerator, the reinforcing agent, and the rubber component is preferably 80 to 200 ° C, more preferably 100 to 190 ° C, and particularly preferably. It should be in the range of 140 to Ί80 ° C. Next, the obtained kneaded product is cooled to preferably 100 ° C. or lower, more preferably 80 ° C. or lower, and then kneaded with a crosslinking agent and a crosslinking accelerator.

 Further, the rubber composition containing a reinforcing agent can be obtained as a wet master batch rubber by mixing a reinforcing agent in a predetermined ratio in advance into the polymer latex before obtaining the solid rubber.

 The rubber composition of the present invention is usually used after crosslinking. The crosslinking method is not particularly limited, and may be selected according to the shape and size of the crosslinked product. The crosslinkable rubber composition may be filled in a mold and heated to perform crosslinking at the same time as molding. Alternatively, the crosslinkable rubber composition molded in advance may be heated to perform crosslinking. The crosslinking temperature and the crosslinking time are not particularly limited, and may be selected according to the shape and size of the crosslinked product. The crosslinking temperature is preferably from 120 to 200 ° C, more preferably from 140 to 180 ° C.

 (Example)

 Hereinafter, the present invention will be described specifically with reference to Examples. Parts and percentages in Examples and Comparative Examples are based on weight unless otherwise specified.

 The properties of the copolymer rubber, oil point rubber, rubber composition and crosslinked rubber were evaluated by the following methods.

 (1) Styrene unit content in the copolymer: Measured according to JIS K 6383 (refractive index method).

(2) Amino group-containing monomer unit amount in copolymer: The copolymer is dissolved in tetrahydrofuran, and reprecipitation purification is performed twice with a mixed solvent of methanol and acetone (11 by volume), and vacuum is applied. After drying, it was measured at 500 MHz ¹ H—NMR.

(3) Epoxy group-containing monomer unit in the copolymer: Dissolve the copolymer in tetrahydrofuran and reprecipitate twice with a mixed solvent of methanol / acetone (1/1 volume ratio). The sample was purified and dried under vacuum to obtain a sample. Dissolve the sample in tetrahydrofuran and add an excess of 0.1 N hydrochloric acid-acetone solution (0.1 N hydrochloric acid aqueous solution.

0.01 N hydrochloric acid-acetone solution), and react with the epoxy groups in the copolymer.

Titration was performed with a 1N alcoholic hydroxylating solution, the amount of epoxy in the copolymer was calculated, and the amount of epoxy group-containing monomer units was determined.

(4) Viscosity (ML _{1 + 4} , Ί 00 ° C): Measured according to JISK630.

 (5) Tensile properties: The stress at 300% elongation (MPa) was measured in accordance with JIS K6301. This property was expressed as an index (tensile property index) using the reference sample as 100. The larger the value, the better.

 (6) Low heat build-up: Using RDA-II manufactured by Rheometrics, tan (5 was measured at 60 ° C under the condition of 0.5% twist and 20 Hz. The index is shown as an index (low exothermic index) with the sample being 100. The larger the value, the better.

 (7) Processability: After kneading the rolls, observe the sheet-like sample taken out so that the thickness of the sheet becomes 3 mm, and determine the smoothness of the surface skin and the continuity of the edge portion of the sheet as follows. It was scored based on the standard and judged by the total score. The larger the total score, the better the workability. If the score is 5 or more, no problems occur in the post-process such as the green tire molding process.

 Surface skin smoothness

 4 points: The surface is smooth and shiny.

 3 points: The surface is almost smooth but not glossy.

 2 points: There are four protrusions.

 1 point: There are many irregularities and the depth of the irregularities is deep.

 Edge continuity

 4 points: smooth.

 3 points: There are a few irregularities.

2 points: Many irregularities. 1 point: There are many deep cuts.

 (Preliminary experiment)

 In a pressure-resistant reactor equipped with a stirrer, 200 parts of deionized water, 2 parts of rosin acid stone, 2.1 parts of fatty acid stone, 56.8 parts of 1,3-butadiene, 42.5 parts of styrene, and t- Dodecyl mercaptan was charged with 0.16 parts. At a reactor temperature of 8 ° C, 0.1 part of diisopropylbenzene hydride peroxide as a polymerization initiator, 5 parts of a deionized aqueous solution in which 0.2 parts of sodium, formaldehyde and sulfoxylate were dissolved, and sodium ethylenediaminetetraacetate Two parts of a deionized aqueous solution in which 0.004 parts of ferric sulfate and 0.04 parts of ferric sulfate were dissolved was added to the reactor to initiate polymerization. When the polymerization conversion in the polymerization system reached 45%, the reaction was stopped by adding 0.05 parts of getyl hydroxylamine to 100 parts of the polymer.

 After removing the unreacted monomer from the obtained polymer latex by steam distillation, 100 parts of the polymer was treated with octadecyl 3- (3,5-zy t-butyl 4-) as an anti-aging agent. 0.8 parts of hydroxyphenyl) probionet and 0.2 parts of 2,4-bis (n-octylthiomethyl) -16-methylphenol were added. This polymer latex was coagulated with sodium chloride while adjusting the pH to 3 to 5 with sulfuric acid to obtain a crumb-like polymer. The crumb was dried with a hot air dryer at 80 ° C to obtain a solid rubber. The Mooney viscosity of the rubber was measured and found to be in the range of 70 to 200.

 Example 1

A pressure-resistant reactor equipped with a stirrer was charged with 200 parts of deionized water, 2 parts of rosin stone, 2.1 parts of fatty acid stone, a monomer having an initial charge composition shown in Table 1, and t-dodecyl mercaptan. The reactor temperature was set to 8 ° C, 0.1 parts of diisopropylbenzene hydroperoxide as a polymerization initiator, 5 parts of a deionized aqueous solution in which 0.2 parts of sodium diformaldehyde's sulfoxylate was dissolved, and 5 parts of ethylenediaminetetraacetate. To the reactor was added 2 parts of a deionized aqueous solution in which 0.004 parts of trium and 0.04 parts of ferric sulfate were dissolved, and polymerization was started. When the polymerization conversion in the polymerization system reached 45%, a part of the polymer latex in the polymerization system was withdrawn, and 100 parts of the polymer contained therein was replaced with 0 parts of getylhydroxylamine. 0 Stop the reaction by adding 5 parts I let you. Immediately after the removal of the polymer latex during the above reaction, the polar group-containing monomer and t-dodecylmercaptan were added to the polymerization reaction system at the ratio shown in the immediately following post-addition composition to carry out the polymerization reaction. Continued. When the polymerization conversion in the polymerization system reached 70%, the reaction was stopped by adding getylhydroxylamine to 0.05 part with respect to 100 parts of the polymer. I let it.

 After unreacted monomers are removed from the latex withdrawn during the reaction by steam distillation, 100 parts of the polymer is treated as an anti-aging agent with octadecyl 3- (3-, 3-di-t-t). 0.8 parts of butyl 4-hydroxyphenyl) propionate and 0.2 parts of 2,4-bis (n-methyloctylthiomethyl) -16-methylphenol were added as emulsified dispersions. This was coagulated with sodium chloride while adjusting the pH to 3 to 5 with sulfuric acid to obtain a crumb-like polymer. The crumb was dried with a hot air drier at 80 ° C to obtain a solid rubber. Table 1 shows the viscosity of the polymer in the extracted latex.

 After unreacted monomers are removed from the finally obtained polymer latex by steam distillation, N- (1,3-dimethylbutyl) is used as an antioxidant for 100 parts of the polymer. 0.2 parts of 1 N'-phenyl-p-phenylenediamine and 0.13 parts of 2,2,4-trimethyl-1,2-dihydroquinoline were added as an emulsified dispersion, and conjugated rubber A A polymer latex was obtained.

 A part thereof was taken out, and the polymer latex was coagulated with sodium chloride while adjusting the pH to 3 to 5 with sulfuric acid to obtain a crumb-like polymer. This crumb was dried with a hot air drier at 80 ° C. to obtain a conjugated rubber A. Table 1 shows the composition and the Mooney viscosity of the obtained rubber.

In a polymer latex of conjugated gen-based rubber A, 37.5 parts of Enernene 184 A (manufactured by Pretty Petroleum Co.) was used as an extension oil for 100 parts of all polymers by emulsification and dispersion. Added as a liquid. Thereafter, the polymer latex containing the extended oil was coagulated with sodium chloride while adjusting the pH to 3 to 5 with sulfuric acid to obtain a crumb-like solid. The crumb was dried with a hot air dryer at 80 ° C to obtain an oil-extended rubber. Table 1 shows the Mooney viscosity of the obtained oil-extended rubber. Using a Brabender type mixer, 137.5 parts of the above oil-extended rubber (equivalent to 100 parts of rubber) was masticated for 30 seconds at a starting temperature of 110 ° C, and then silica ( Zeosil 1 16 5 MP: Rhodia 5 3 parts and silane coupling agent (Si 69: Degussa) 6. Add 4 parts, knead for 2 minutes, and then add silica (Zeosil 1 16) 5 MP: made by Rhodia Co., Ltd. 27 parts, zinc oxide (grain size 4 m, zinc flower # 1: made by Honjo Chemical Co., Ltd.) 3 parts, stearic acid 2 parts, and antioxidant (Nocrack 6C: made by Ouchi Shinko Co., Ltd.) 2) was added and kneaded for 2 minutes. The temperature at the end of the mixing was 150 ° C.

 The kneaded product obtained was mixed with 1.4 parts of sulfur and a crosslinking accelerator (a mixture of 1.8 parts of N-cyclohexyl-2-benzothiazylsulfenamide and 1.7 parts of diphenyldananidin) in 5 parts. After kneading with an open roll at 0 ° C, the mixture was taken out into a sheet. The workability was evaluated by observing the surface skin and edge portion of the above sheet. Table 1 shows the results.

 The sheet containing the vulcanizing agent was press-crosslinked at 160 ° C for 30 minutes to prepare a test piece, and the physical properties of the crosslinked rubber were evaluated. The results are shown to the meeting. However, in the occlusion, the stress at 300% elongation and t an <5 are expressed using Comparative Example 2 as a reference (index 100).

 Examples 2 and 3

 Except for changing the initial charge composition and post-addition composition shown in Table 1, a conjugated gen-based rubber, an oil-extended rubber, a rubber composition and a crosslinked rubber were produced in the same manner as in Example 1, and their properties were evaluated. The results are shown directly above.

 Examples 4 and 5

 同 様 Same as Example 1 except that the initial charge composition and post-addition composition shown above were changed, and the conditions for coagulating the polymer latex were adjusted to pH 7, and calcium chloride was used. A conjugated gen-based rubber, an oil-extended rubber, a rubber composition, and a cross-linked rubber were produced, and their properties were evaluated. Table 1 shows the results.

 Comparative Examples 1 to 4

Except that the initial charge composition and the post-addition composition shown immediately above were changed, conjugated rubbers, oil-extended rubbers, rubber compositions, and crosslinked rubbers were produced in the same manner as in Example I, and their properties were evaluated. Table 1 shows the results. Example Comparison-

1 2 3 4 5 1 2 3 4 Conjugated rubber A Β C D ε F H J Initial charge composition (parts)

 1 3—Pigs 56.8 56.1 56,7 57.2 57.2 57.5 56,9 56.8 56.3 Styrene 42.5 42.5 42.S 42.5 42.5.42 . 5 42. .5 42. 5 42. 5 — Thousand J Rare s Noprod) Reak ^ / Rare ― ― 0.1 1 _ 0. 6 0.35 Geri Siji J Remeichi K _ '― _ . 0, 05 one ....

* ■ ― K ^^ J then J: F 0.16 0. 1 5 0. 1. 0. 1 6 0. 1 0. 1 Z 0. 1 3 0. 1 6 5 0. 1 3

Addition of S-functional group-containing simple substance ^ in the initial preparation (%) 0 0 1 2.50 0 16.7-1 00 0 50 ΐ £ ½∑Λί 9 — JXK ^ i ^^ Pi—child tt and ^C Λ village q-time -

 1 1 5 1 35 1 40 1 1 7 1 37 1 32 1 07 1 35 Knee viscosity

 .¾Additive composition (parts)

 ―Dodecyl mercaptan 0.05 0.1 5 0.1 5 0.1 5 0.1 5 0.05 0.O 5 0.0 1 0.05

N.N-Dimethylaminopropyl acrylamide 0.7 0.a 0.7 1---O. 7 0.35 glycidyl methacrylate 1--0.3 0.25 1-1-1 Conjugate Composition of Gen-based Rubber (½)

 Styrene unit 35.5 36.0 34.9 35.2 35.7 35.4 35.3 35.4 4.35.0

N, N-Dimethylaminopropyl acrylamide unit 0.4 O. 5 0.5--1 0.4 O. 0.40, 4. Glycidyl methacrylate unit---0.4. 4--- ― Muffin viscosity of conjugated rubber 1 0 α 1 1 2 1 1 3 95 1 8 1 1 5 1 1 1 1 1 0 1 1 5 Mummie viscosity of oil-extended rubber 4 ζ 52 53 38 55 53 50 50 52 Physical properties of rubber composition

 Sheet skin (dots) 3 3 2 3 2 3 1 1 1 Sheet edge (dots) 4 3 3 3 3 4 1 1 1 Workability (dots) 7 6 5 6 5 7 2 2 2

300½ stress at extension (pointing) 1 03 t 0 & 1 1 8 1 05 1 20 90 1 00 96 99 tand (index) 1 0 Ζ 1 04 1 06 1 02 1 0 a 9 1 1 00 98 1 01

Table 1 shows the following.

 The silica-containing rubber composition of Comparative Example 1 using the conjugated diene rubber F without using the polar group-containing monomer has excellent workability, but is inferior in tensile properties and low heat build-up. The silica-containing rubber composition of Comparative Example 2 using the conjugated diene rubber G obtained by charging the entire amount of the polar group-containing monomer before the start of polymerization is superior to Comparative Example 1 in tensile properties and low heat build-up. However, processability is poor.

 Although the polar group-containing monomer is added during the polymerization, the difference in the Mooney viscosity between the polymer present in the reaction system at the time of the addition and the finally obtained conjugated diene rubber is the present invention. The silica-containing rubber composition of Comparative Example 3 using the conjugated diene rubber H out of the specified range is inferior in processability, and inferior in tensile properties and low heat build-up.

 Although the polar group-containing monomer was added during the polymerization, the addition at the initial preparation was larger than the range specified in the present invention. However, the tensile properties and low heat build-up are comparable to those of Comparative Example 2 (initial charge of polar group-containing monomer: 100%), and the processability is also inferior.

 Compared with these comparative examples, the silica-containing rubber compositions of Examples 1 to 5 using the conjugated gen-based rubbers A to E within the range specified in the present invention are excellent in processability, and have excellent tensile properties and Excellent low heat generation. Industrial applicability

 The conjugated rubber of the present invention is excellent in the surface shape of a sheet when a compound containing silica as a reinforcing agent is formed into a sheet by a roll, and is excellent in tensile properties and low heat generation.

 Accordingly, the rubber composition containing the conjugated rubber of the present invention can be used in various applications that make use of its properties, for example, tire members such as treads, under treads, carcass, sidewalls, and bead portions; hoses, It can be used for window frames, belts, shoe soles, anti-vibration rubber, anti-vibration rubber, rubber parts for automobile parts, etc .; resin-reinforced rubber parts such as high-impact polystyrene and ABS resin. Above all, it is suitable as a tire member and particularly suitable as a tire tread for a fuel-efficient tire.

Claims

The scope of the claims 1. From 40 to 9.9% by weight of conjugated diene monomer unit, from 0 to 5.9% by weight of aromatic vinyl monomer unit and from 0.1 to 20% by weight of polar group-containing monomer unit A conjugated diene rubber having a Mooney viscosity (M l) of 20 to 50, wherein at least a part of the conjugated diene monomer and at least a part of the aromatic vinyl monomer used for the polymerization are used. Polymerization of a monomer mixture containing no polar group-containing monomer or containing less than 30% by weight of the monomer mixture is started, and the remainder of the conjugated diene monomer and the remainder of the aromatic vinyl monomer are polymerized. By the time the reaction is stopped, the addition is completed, and the remainder of the polar group-containing monomer and the molecular weight modifier are mixed with each other so that the viscosity of the polymer in the reaction system (Μ2) is 70 to 200. A conjugated gen-based rubber which is obtained by adding it during a period of 5 or more higher than the above 1 and continuing the polymerization.  2. Conjugated diene monomer unit 50-8.9% by weight, aromatic vinyl monomer unit 10-4-9. 9% by weight and polar group-containing monomer unit 0.2-10% by weight The conjugated gen-based rubber according to claim 1, comprising:  3. The conjugated gen-based rubber according to claim 1 or 2, wherein the rubber has a monomer viscosity (M l) of 50 to 140.  4. The conjugated rubber according to any one of claims 1 to 3, wherein the conjugated diene monomer is 1,3-butadiene and the aromatic vinyl monomer is styrene.  5. When the polar group-containing monomer is an amino group, an epoxy group, an alkoxysilyl group, an aryloxysilyl group, a hydroxyl group, a sulfido group, a disulfide group, a sulfonyl group, a sulfinyl group, a carbonyl group, or an imino. The conjugated rubber according to any one of claims 1 to 4, which is a monomer having a polar group selected from a group and an imide group.  6. The method according to any one of claims 1 to 4, wherein the polar group-containing monomer is a monomer having a polar group selected from an amino group, an epoxy group, an alkoxysilyl group, an aryloxysilyl group and a hydroxyl group. The conjugated rubber according to any one of the above. 7. The conjugated rubber according to any one of claims 1 to 4, wherein the polar group-containing monomer is a monomer having a polar group selected from an amino group and an epoxy group. 8. Contains at least 80% by weight of the conjugated diene monomer and at least 80% by weight of the aromatic vinyl monomer used in the polymerization, and contains no polar group-containing monomer or 25% by weight thereof. The conjugated rubber according to any one of claims 1 to 7, which is obtained by initiating initial polymerization using a monomer mixture containing less than.  9. Contains at least 90% by weight of the conjugated diene monomer and at least 90% by weight of the aromatic vinyl monomer used in the polymerization, and does not contain the polar group-containing monomer or 23% by weight thereof. The conjugated rubber according to any one of claims 1 to 7, which is obtained by initiating initial polymerization using a monomer mixture containing less than.  10. If the total amount of the conjugated monomer and the total amount of the aromatic vinyl monomer used in the polymerization were not included in the monomer mixture at the beginning of the initial polymerization, the polymerization reaction system The conjugated rubber according to any one of claims 1 to 9, which is obtained by adding the remaining amount of said monomer when the polymerization addition ratio is less than 65%.  11. After the start of the polymerization, the remainder of the polar group-containing monomer and the molecular weight modifier were mixed with each other so that the polymer in the reaction system had a Mooney viscosity (M 2) in the range of 80 to 150. The conjugated diene rubber according to any one of claims 1 to 10, wherein the conjugated rubber is obtained by being added while being added 8 to 50 times higher than M 1 to continue the polymerization.  1 2. After the start of the polymerization, the remainder of the polar group-containing monomer and the molecular weight modifier were mixed with each other so that the polymer in the reaction system had a Mooney viscosity (M 2) in the range of 90 to 140. The conjugated rubber according to any one of claims 1 to 10, wherein the conjugated rubber is obtained by being added while being 10 to 45 higher than M 1 and continuing polymerization.  1 3. After the start of polymerization, when the amount of polymer formed in the reaction system is in the range of 20 to 80% by weight of the total amount of conjugated The conjugated rubber according to any one of claims 1 to 12, which is obtained by adding the remaining monomer and continuing the polymerization.  14. The conjugated rubber according to any one of claims 1 to 13, which is obtained by polymerization by an emulsion polymerization method. 15. An oil-extended rubber comprising 100 parts by weight of the conjugated diene rubber according to any one of claims 1 to 13 and 5 to 100 parts by weight of an extension oil. 1 6. A rubber composition containing the conjugated rubber according to any one of claims 1 to 13.  1 7. A rubber composition containing the oil-extended rubber according to claim 15.  Claims 16 or 17 wherein at least one reinforcing agent selected from silica and carbon black is contained in an amount of 10 to 200 parts by weight with respect to 100 parts by weight of the rubber component. The rubber composition according to the above.  10.9 100 parts by weight of rubber component, 100 to 200 parts by weight of silica, and 100 to 100 parts by weight of silica, 0.1 to 30 parts by weight of silane coupling agent The rubber composition according to claim 16, comprising parts by weight.  20. A crosslinkable rubber crosslinked product obtained by blending a vulcanizing agent with the rubber composition according to any one of claims 16 to 19.  2 1. A cross-linked rubber obtained by cross-linking the cross-linkable rubber cross-linked product according to claim 20.