JP2003238604A - Conjugated diene rubber, oil-extended rubber and rubber composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a conjugated diene rubber which gives a sheet having a good surface feature when compounding it with silica as a reinforcement followed by molding the compound to a sheet shape using a roll and also has a good tesile property and a good low heat buildup, and to provide an oil- extended rubber and a rubber composition. <P>SOLUTION: The conjugated diene rubber has Moony viscosity (M1) of 20-150 and is specifically obtained by that, polymerization of a monomer mixture consisting of at least a partial amount of a conjugated diene monomer, at least a partial amount of an aromatic vinyl monomer and less than 30 wt.% of a polar group-having monomer based on each the total amount to be used, is started, addition of the residual amounts of the conjugated diene monomer and aromatic vinyl monomer is completed by the termination of the polymerization and the residual amount of the polar group-containing monomer and a molecular weight controller are added when Moony viscosity of the polymer in the reaction system (M2) is in the range of 70-200 (M1 is lower than M2 at least by 5) allowing the polymerization to continue. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conjugated diene rubber, an oil-extended rubber and a rubber composition, and more specifically to a sheet obtained by molding a composition containing silica as a reinforcing agent into a sheet with a roll. Excellent surface shape, and
The present invention relates to a conjugated diene rubber, an oil-extended rubber, and a rubber composition which have excellent tensile properties and low heat buildup.

[0002]

2. Description of the Related Art In recent years, resource saving and environmental measures have been emphasized, and the demand for low fuel consumption of automobiles has become more and more stringent. By reducing rolling resistance of automobile tires, it contributes to lower fuel consumption. Is required to do. In order to reduce the rolling resistance of the tire, it is known to use a rubber composition in which silica is blended in the conjugated diene rubber as a reinforcing agent, instead of carbon black. Since such a silica-containing rubber composition is superior in low heat build-up to a carbon black-containing rubber composition, it can reduce rolling resistance of the tire, but is inferior in abrasion resistance and tensile properties. In order to improve this problem, it has been proposed to use a diene rubber in which a monomer having an amino group is copolymerized.

For example, Japanese Patent Laid-Open No. 64-22940 discloses a solution containing a conjugated diene rubber in which an amino group-containing monomer is copolymerized by solution polymerization using an organic alkali metal as a polymerization catalyst. A silica-blended rubber composition having improved wear resistance is disclosed. The conjugated diene rubber includes natural rubber and styrene having a Mooney viscosity of about 50.
Specific formulation examples in which a butadiene copolymer rubber is blended are also disclosed. However, since such a conjugated diene rubber generally has a narrow molecular weight distribution, it is inferior in processability, and although the above-mentioned rubber blend is slightly improved in processability, it is inferior in balance between low heat build-up and tensile properties.
A rubber composition having poor workability has a deteriorated surface shape of the rubber composition formed into a sheet by a roll, making it difficult to form a green tire in the tire manufacturing process.

Further, JP-A-1-101344 discloses that it contains a conjugated diene rubber obtained by emulsion-copolymerizing a tertiary amino group-containing monomer in an amount of 1 to 20% by weight. An excellent silica-containing rubber composition is disclosed, and specific compounding examples in which natural rubber or a styrene-butadiene copolymer rubber having a Mooney viscosity of about 50 is blended with the conjugated diene rubber is also disclosed. However, a rubber composition containing such a conjugated diene rubber is inferior in processability, and the above rubber blend is inferior in processability and inferior in balance between low heat build-up and tensile properties.

Further, JP-A-8-134272 discloses that a conjugated diene rubber obtained by copolymerizing less than 1% by weight of a tertiary amino group-containing monomer and a silane coupling agent are contained under specific conditions. A kneaded silica compounded rubber composition is disclosed. Although such a rubber composition is excellent in extrudability, tensile properties, and low heat build-up, the surface shape of the rubber composition when formed into a sheet by a roll is not satisfactory. .

[0006]

In view of the above circumstances, an object of the present invention is to provide an excellent surface shape of a sheet when a composition containing silica as a reinforcing agent is formed into a sheet with a roll, and Another object of the present invention is to provide a conjugated diene rubber, an oil-extended rubber and a rubber composition which are excellent in tensile properties and low heat buildup.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies in order to achieve the above-mentioned object, and when copolymerizing 1,3-butadiene, styrene and an amino group-containing monomer, After initiating the polymerization of 1,3-butadiene and styrene, in the state where a polymer having a relatively high Mooney viscosity is present in the reaction system, the amino group-containing monomer and the molecular weight modifier are added to continue the polymerization. By using a conjugated diene-based rubber obtained as a result, a silica compound with an excellent surface shape of the sheet when a compound containing silica as a reinforcing agent is formed into a sheet with rolls, and with excellent tensile properties and low heat buildup It was found that a rubber composition can be obtained, and the present invention has been completed based on this finding.

Thus, according to the invention, conjugated diene monomer units 40 to 99.9% by weight, aromatic vinyl monomer units 0 to 59.9% by weight and polar group-containing monomer units 0.
Mooney viscosity (M1) of 1 to 20% by weight is 20
To 150 conjugated diene rubbers containing at least a part of the conjugated diene monomer used for the polymerization, at least a part of the aromatic vinyl monomer and less than 30% by weight of the polar group-containing monomer. Polymerization of the monomer mixture is started, 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, and the remainder of the polar group-containing monomer and the molecular weight The Mooney viscosity (M2) of the polymer in the reaction system with the regulator is in the range of 70 to 200 (however,
M1 is lower than M2 by 5 or more. ), And the polymerization is continuously obtained to provide a conjugated diene rubber. Further, according to the present invention, there is provided an oil-extended rubber comprising the conjugated diene rubber and the extension oil. Further, according to the present invention, there is provided a rubber composition containing the conjugated diene rubber.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is described in detail below.
The conjugated diene rubber of the present invention has a conjugated diene monomer unit 4
0-99.9% by weight, aromatic vinyl monomer unit 0-5
9.9% by weight and polar group-containing monomer unit 0.1 to 20
Mooney viscosity (M1) of 20 to 150% by weight
A conjugated diene rubber, comprising at least a part of the conjugated diene monomer used for polymerization, at least a part of the aromatic vinyl monomer and less than 30% by weight of the polar group-containing monomer. Polymerization of the mixture is started, 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, and the remainder of the polar group-containing monomer and the molecular weight modifier are added. And the Mooney viscosity (M2) of the polymer in the reaction system is in the range of 70 to 200 (where M1 is M
5 or more lower than 2. ) Is added during this time and polymerization is continuously obtained.

The conjugated diene rubber is a conjugated diene monomer unit 40 to 99.9% by weight, preferably 50 to 89.8% by weight, more preferably 55 to 79.7% by weight, aromatic vinyl monomer. Unit 0-59.9% by weight, preferably 10
49.8 wt%, more preferably 20 to 44.7 wt%, and polar group-containing monomer unit 0.1 to 20 wt%,
Preferably 0.2 to 10% by weight, more preferably 0.3.
% Of its Mooney viscosity (ML _{1 + 4} ,
100 ° C .: Hereinafter, it may be abbreviated as “M1”. ) Is 20
~ 150, preferably 50-140, more preferably 8
It is in the range of 0 to 130.

When the amount of the conjugated diene monomer unit is small, the low exothermic property is poor. If there are many aromatic vinyl monomer units, the low heat buildup is poor. From the viewpoint of being more excellent in tensile properties, it is preferable to contain an aromatic vinyl monomer unit. When there are few polar group-containing monomer units, low heat buildup and poor tensile properties are inferior, and when there are many,
The surface shape of the silica-containing rubber composition formed into a sheet by a roll becomes poor. If the Mooney viscosity is low, the heat build-up and tensile properties are inferior. If the Mooney viscosity is too high, the surface shape of the silica compounded rubber composition molded into a sheet with rolls deteriorates, or the compound viscosity becomes too high and processing becomes difficult. .

The conjugated diene rubber is a monomer other than the conjugated diene monomer unit, the aromatic vinyl monomer unit and the polar group-containing monomer unit, as long as the effect of the present invention is not essentially impaired. The body unit may be included. This amount is preferably 20% by weight or less, more preferably 10% by weight or less. If this amount is too large, the balance of the physical properties of the crosslinked rubber tends to deteriorate.

As the conjugated diene monomer, for example, 1,
3-butadiene, 2-methyl-1,3-butadiene,
2,3-dimethyl-1,3-butadiene, 2-chloro-
1,3-butadiene, 1,3-pentadiene and the like can be mentioned. Among these, 1,3-butadiene is preferable. These may 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, for example, styrene, α-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 2,4-diisopropylstyrene, 2,4-dimethylstyrene, 4-t-
Butyl styrene, 5-t-butyl-2-methyl styrene, monochlorostyrene, dichlorostyrene, monofluorostyrene and the like can be mentioned. Of these, styrene is preferable. These can be used alone or in 2
A combination of two or more species can be used.

The polar group in the polar group-containing monomer is not particularly limited as long as it can react with the silica surface,
For example, amino group, epoxy group, alkoxysilyl group,
Allyloxysilyl group, hydroxyl group, sulfide group,
Examples thereof include a disulfide group, a sulfonyl group, a sulfinyl group, a thiocarbonyl group, an imino group and an imide group. Among these, an amino group, an epoxy group, an alkoxysilyl group, an allyloxysilyl group, and a hydroxyl group are preferable, and an amino group, an epoxy group, an alkoxysilyl group,
An allyloxysilyl group is more preferable, and an epoxy group and an amino group are particularly preferable.

The amino group-containing monomer is the first in one molecule.
It is a polymerizable monomer having at least one amino group selected from primary, secondary and tertiary amino groups, and among them, a monomer having a tertiary amino group is preferable.

Examples of the primary amino group-containing monomer include p-aminostyrene, aminomethyl (meth) acrylate, aminoethyl (meth) acrylate, aminopropyl (meth) acrylate, aminobutyl (meth) acrylate, etc. Is mentioned.

As the secondary amino group-containing monomer, for example, anilinostyrenes disclosed in JP-A-61-130355; N-methyl (meth) acrylamide,
Examples include N-mono (meth) acrylamides, N-methylolacrylamides, N- (4-anilinophenyl) methacrylamides and other N-monosubstituted (meth) acrylamides;

Examples of the tertiary amino group-containing monomer include N, N-disubstituted aminoalkyl (meth) acrylate, N, N-disubstituted aminoalkyl (meth) acrylamide, N, N-disubstituted amino. Examples thereof include aromatic vinyl compounds and polymerizable monomers having a pyridyl group.

Examples of the N, N-disubstituted amino (meth) acrylate include N, N-dimethylaminomethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate and N, N-dimethylaminopropyl. (Meth) acrylate, N, N-dimethylaminobutyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N, N-diethylaminopropyl (meth) acrylate, N, N-diethylaminobutyl (meth) acrylate, N-methyl-N-ethylaminoethyl (meth) acrylate, N, N-dipropylaminoethyl (meth) acrylate, N, N-dibutylaminoethyl (meth) acrylate, N, N-dibutylaminopropyl (meth) acrylate , N, N-dibutylaminobutyl (me ) Acrylate, N, N- dihexylaminoethyl (meth) acrylate, N, etc. N- dioctyl aminoethyl (meth) acrylate. Among these, N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate and N, N-dipropylaminoethyl (meth) acrylate are preferable.

Examples of N, N-disubstituted aminoalkyl (meth) acrylamides are 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-
Diethylaminopropyl (meth) acrylamide, N,
N-diethylaminobutyl (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-dioctylaminopropyl (meth) acrylamide, etc. Is mentioned. Among these, N, N-dimethylaminopropyl (meth) acrylamide and N, N-diethylaminopropyl (meth) acrylamide are preferable.

Examples of the N, N-disubstituted aminoaromatic vinyl compound include N, N-dimethylaminoethylstyrene, N, N-diethylaminoethylstyrene and N, N.
-Dipropylaminoethylstyrene, N, N-dioctylaminoethylstyrene and the like can be mentioned.

Examples of the polymerizable monomer having a pyridyl group include 2-vinylpyridine, 4-vinylpyridine, 5-methyl-2-vinylpyridine and 5-ethyl-2.
-Vinyl pyridine and the like. Among these,
2-vinyl pyridine and 4-vinyl pyridine 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.
Examples of the epoxy group-containing monomer include glycidyl (meth) acrylate, 3,4-epoxybutyl (meth) acrylate, 3,4-oxycyclohexyl (meth) acrylate, N-glycidyl (meth) acrylamide, vinylglycidyl ether. , Allyl glycidyl ether, 2-methyl allyl glycidyl ether, 3,4
-Epoxy-1-butene, 3,4-epoxy-1-methyl-1-butene, 3,4-epoxy-1-pentene,
3,4-epoxy-3-methyl-1-pentene, 5,6
-Epoxy-1-hexene, vinylcyclohexene monoxide, styrene-p-glycidyl ether and the like. Of these, glycidyl (meth) acrylate is preferable. 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, β- (meth) acryloxyethyltrimethoxysilane, and β- (meth) acryl. Roxyethyltriethoxysilane, γ- (meth) acryloxypropyltrimethoxysilane, γ- (meth) acryloxypropyltriethoxysilane, γ- (meth) acryloxypropyltripropoxysilane, γ- (meth) acryloxypropyl Tributoxysilane, γ- (meth) acryloxypropylmethyldimethoxysilane, γ- (meth) acryloxypropylethyldimethoxysilane, γ- (meth) acryloxypropylhexyldimethoxysilane, β-acryloxyethyloxymethyltrimethoxysilane , Γ Examples thereof include-(β-acryloxyethyloxy) propyltrimethoxysilane and γ- (γ-methacryloxypropyloxy) propyltrimethoxysilane. Among these, γ- (meth) acryloxypropyltriethoxysilane, γ- (meth) acryloxypropyltripropoxysilane, γ- (meth) acryloxypropyltributoxysilane, γ- (β-acryloxyethyloxy) Propyltributoxysilane and γ- (γ-methacryloxypropyloxy) propyltributoxysilane are preferable, and γ- (meth) acryloxypropyltripropoxysilane and γ- (meth) acryloxypropyltributoxysilane are more preferable. These alkoxysilyl group-containing monomers can be used alone or in combination of two or more.

The allyloxysilyl group-containing monomer is a polymerizable monomer having at least one allyloxysilyl group in one molecule. Examples of the aryloxysilyl group-containing monomer include (meth) acryloxymethyltriphenoxy, β- (meth) acryloxyethyltriphenoxysilane, γ- (meth) acryloxypropyltriphenoxysilane, γ- (meth ) Acryloxypropylmethyldiphenoxysilane, γ- (meth) acryloxypropylethyldiphenoxysilane, γ- (meth) acryloxypropylhexyldiphenoxysilane, β-acryloxyethyloxymethyltriphenoxysilane, γ- (β
Examples include -acryloxyethyloxy) propyltriphenoxysilane and γ- (γ-methacryloxypropyloxy) propyltriphenoxysilane. Among these, γ- (meth) acryloxypropyltriphenoxysilane and γ- (meth) acryloxypropylmethyldiphenoxysilane are preferable. These allyloxysilyl 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. Specific examples of the hydroxyl group-containing monomer include, for example, hydroxymethyl (meth) acrylate and 2-hydroxyethyl (meth).
Acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 3-chloro-2-hydroxypropyl (meth) acrylate, 3-phenoxy-2-hydroxypropyl (meth) acrylate, glycerol mono (meth ) Acrylate, hydroxybutyl (meth) acrylate, 2
-Chloro-3-hydroxypropyl (meth) acrylate, hydroxyhexyl (meth) acrylate, hydroxyoctyl (meth) acrylate, hydroxymethyl (meth) acrylamide, 2-hydroxypropyl (meth) acrylamide, 3-hydroxypropyl (meth)
Acrylamide, di- (ethylene glycol) itaconate, di- (propylene glycol) itaconate, bis (2-hydroxypropyl) itaconate, bis (2
-Hydroxyethyl) itaconate, bis (2-hydroxyethyl) fumarate, bis (2-hydroxyethyl) malate, 2-hydroxyethyl vinyl ether,
Examples thereof include hydroxymethyl vinyl ketone and allyl alcohol. Among these, hydroxymethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 3
-Phenoxy-2-hydroxypropyl (meth) acrylate, glycerol mono (meth) acrylate, hydroxybutyl (meth) acrylate, hydroxyhexyl (meth) acrylate, hydroxyoctyl (meth)
Acrylate, 2-hydroxypropyl (meth) acrylamide, 3-hydroxypropyl (meth) acrylamide and the like are preferable.

Other monomers other than the conjugated diene, the aromatic vinyl monomer and the polar group-containing monomer are not particularly limited as long as they can be copolymerized with the conjugated diene, and specific examples thereof include Methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, dibutyl maleate, diethyl fumarate, dibutyl itaconate, etc. Ethylenically unsaturated carboxylic acid alkyl ester monomer; (meth) acrylic acid, maleic acid, fumaric acid, monoethyl maleate, monobutyl fumarate and other ethylenically unsaturated carboxylic acid monomers; (meth)
Ethylenically unsaturated nitrile monomers such as acrylonitrile; α-olefins such as ethylene and propylene; vinyl chloride, vinyl acetate and the like.

The conjugated diene rubber of the present invention comprises at least part of the conjugated diene monomer used for polymerization, at least part of the aromatic vinyl monomer and 30 parts of the polar group-containing monomer.
Polymerization of a monomer mixture containing less than wt% is started, 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, and the polar group-containing monomer is added. The rest of the monomer and the molecular weight modifier are added while the Mooney viscosity (M2) of the polymer in the reaction system is in the range of 70 to 200 (where M1 is 5 or more lower than M2) and the polymerization is continued. It is characterized by being obtained.

The monomer composition used for the polymerization may be appropriately determined so that the composition of the conjugated diene rubber falls within a predetermined range. However, the monomer mixture at the time of initiating the polymerization is less than 30% by weight of at least a part of the conjugated diene monomer used for the polymerization, at least a part of the aromatic vinyl monomer and the polar group-containing monomer. Is required to be included.

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 diene monomer used in the polymerization. The amount of the aromatic vinyl 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 aromatic vinyl monomer used in the polymerization. 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, and particularly preferably less than 20% by weight of the polar group-containing monomer used in the polymerization. is there.

If the ratio of the conjugated diene monomer and the aromatic vinyl monomer at the start of the polymerization is too low, the surface shape of the silica-containing rubber composition molded into a sheet with a roll is deteriorated and the compound viscosity is increased. Tends to be too high. Also,
If the ratio of the polar group-containing monomer at the start of the polymerization is large, the surface shape of the silica-containing rubber composition molded into a sheet by a roll will be deteriorated, and the viscosity of the composition will be too high, which makes processing difficult.

When the amount of the conjugated diene monomer and the aromatic vinyl monomer at the start of the polymerization is not the total amount of the conjugated diene monomer and the aromatic vinyl monomer used for the polymerization, the remaining conjugated diene monomer is used. The monomer and the aromatic vinyl monomer may be added to the polymerization reaction system before the polymerization is stopped. This addition method is not particularly limited, batch addition, divided addition,
Alternatively, a method of continuous addition can be adopted. The addition timing is not particularly limited as long as it is before the termination of the polymerization, but it is preferable to add it at a polymerization conversion rate in the polymerization reaction system of less than 65% by weight, more preferably less than 60% by weight.

After the polymerization is initiated, the remainder of the polar group-containing monomer and the molecular weight modifier have a Mooney viscosity (M2) of 70 to 200, preferably 80 to 15, in the reaction system.
It is essential to add and continue the polymerization while it is in the range of 0, more preferably 90 to 140. When the Mooney viscosity of the polymer present in the polymerization reaction system is low, it is inferior in low heat build-up and tensile properties, and conversely, when it is high, the surface shape of the silica compounded rubber composition molded into a sheet with a roll is deteriorated or compounded. The product viscosity becomes too high, making it difficult to process. If the molecular weight modifier is not added here, the Mooney viscosity of the finally obtained conjugated diene rubber will be high, and the surface shape of the silica compounded rubber composition molded into a sheet with a roll will be deteriorated, and the compound viscosity will be increased. Becomes too high, making it difficult to process. The addition amount of the molecular weight adjusting agent varies depending on the kind of the molecular weight adjusting agent, but may be appropriately adjusted so that M1 and the difference between M1 and M2 are within the range specified in the present invention.

The balance of the polar group-containing monomer used for the polymerization and the addition timing of the molecular weight adjusting agent are preferably almost the same, but the addition timings are staggered within a range that does not substantially impair the effects of the present invention. May be added. The addition method is preferably a batch addition method, but may be a divided addition method or a continuous addition method.

Further, it is essential that M1 is 5 or more lower than M2, M1 is more preferably 8 to 50 lower than M2, and M1 is particularly preferably 10 to 45 lower than M2. If this difference is small, the surface shape of the silica-containing rubber composition molded into a sheet with a roll will be deteriorated, and the viscosity of the composition will be too high, and processing will be difficult.

The amount of the polymer formed in the reaction system when the balance of the polar group-containing monomer is added is preferably 20 to 80% by weight based on the total amount of the conjugated diene rubber obtained by the polymerization.
More preferably 30 to 75% by weight, particularly preferably 40
˜70% by weight. If the ratio is in this range,
Excellent balance of processability, tensile properties and low heat buildup of silica-containing rubber composition.

The polymerization method that can be used in the present invention is not particularly limited, but an emulsion polymerization method, a solution polymerization method, a bulk polymerization method and the like can be mentioned. Among them, the emulsion polymerization method can be preferably adopted because the reaction heat during the polymerization reaction is easily removed and the productivity is excellent.

As the emulsion polymerization method, a usual emulsion polymerization method may be used, for example, a method of emulsifying and dispersing a predetermined amount of the above-mentioned monomer in an aqueous medium in the presence of an emulsifier, and emulsion polymerizing with a polymerization initiator. Is mentioned. The amount of each monomer used is appropriately selected so 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 / or a rosin acid salt is used. Specific examples include potassium or sodium salts of fatty acids such as capric acid, lauric acid, myristic acid, palmitic acid, oleic acid and stearic acid. The amount of the emulsifier 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; combinations of ammonium persulfate and ferric sulfate, combinations of organic peroxide and ferric sulfate, and peroxides. Redox initiators such as a combination of hydrogen oxide and ferric sulfate; and the like. The amount of the polymerization initiator 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.

To adjust the Mooney viscosity of the polymer,
Use a molecular weight regulator. Examples of the molecular weight modifier include mercaptans such as t-dodecyl mercaptan and n-dodecyl mercaptan, carbon tetrachloride, thioglycolic acid, diterpenes, terpinolene, γ-terpinenes. Among them, mercaptans are preferable, and t-dodecyl mercaptan is more preferable and can be used. The amount of the molecular weight modifier used is not particularly limited,
The amount is usually 0.01 to 5 parts by weight, preferably 0.02 to 1 part by weight, and more preferably 0.05 to 0.5 part by weight, based on 100 parts by weight of all the monomers.

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

The polymerization conversion rate when the polymerization reaction is stopped is preferably 85% by weight or less, more preferably 50 to 80% by weight, from the viewpoint of preventing gelation of the polymer. The termination of the polymerization reaction is usually carried out by adding a polymerization terminator to the polymerization system at the time when a predetermined polymerization conversion rate is reached. Examples of the polymerization terminator include amine compounds such as diethylhydroxylamine and hydroxylamine; quinone compounds such as hydroquinone and benzoquinone; sodium nitrite and sodium dithiocarbamate.

After the termination of the polymerization reaction, an antioxidant may be added if necessary. After the termination of the polymerization reaction, unreacted monomer is removed from the obtained polymer latex as needed,
Then, a salt such as sodium chloride, calcium chloride, potassium chloride is used as a coagulant, and if necessary, an acid such as hydrochloric acid or sulfuric acid is added to adjust the pH of the coagulation system to a predetermined value.
The polymer can be solidified and collected as crumb. The crumbs are washed and dehydrated, and then dried with a band dryer or the like to obtain the target conjugated diene rubber. At the time of coagulation, if desired, the polymer latex and the extender oil made into an emulsified dispersion may be mixed in advance and recovered as an oil-extended rubber.

The conjugated diene 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 crosslinked physical properties. As the extender oil used for collecting the oil-extended rubber, those normally used in the rubber industry can be used, and examples thereof include paraffin-based extender oil, aromatic extender oil, and naphthene-based extender oil.

The pour point of the extender oil is preferably -50 to +.
The temperature is 50 ° C, more preferably -10 to + 30 ° C. Within this range, it is easy to stretch and is excellent in the balance between wear resistance and low heat buildup. The aromatic carbon content (CA%) of the extended oil by the Kurtz analysis is preferably 2% or more, more preferably 20% or more, and the paraffin carbon content (CP%) is preferably 70% or less, more preferably Is 55%. If the CA% is too small or the CP% is too large, the tensile properties and wear resistance will be insufficient. The content of polycyclic aromatics in the extender oil is preferably less than 3%. This content is based on the method of IP346 (T
HE INSTITUTE PETROLEUM inspection method).

The amount of the extender oil blended is the conjugated diene rubber 10
With respect to 0 parts by weight, preferably 5 to 100 parts by weight, more preferably 10 to 80 parts by weight, particularly preferably 20 to 6 parts by weight.
0 parts by weight. If the amount of extender oil is in this range,
The viscosity of the compounded mixture of silica is moderate, and the balance between tensile properties and low heat build-up is excellent.

The rubber composition of the present invention contains the above conjugated diene rubber or the oil extended rubber comprising the above conjugated diene rubber and the extender oil.

The rubber composition of the present invention preferably contains silica and / or carbon black as a reinforcing agent, and more preferably contains silica as an essential component. Further, as the reinforcing agent, carbon-silica dual phase filler in which silica is supported on the surface of carbon black may be used.

Examples of silica include dry method white carbon, wet method white carbon, colloidal silica, and precipitated silica disclosed in JP-A-62-62838. Among these, wet-process white carbon containing hydrous silicic acid as a main component is particularly preferable. These silicas can be used alone or in combination of two or more.

The specific surface area of silica is not particularly limited, but is a nitrogen adsorption specific surface area (BET method), preferably 50.
~400m ² / g, more preferably 100~220m ² /
g, particularly preferably 120 to 190 m ² / g. When the specific surface area of 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 ASTM D3037-81.

As the carbon black, for example, furnace black, acetylene black, thermal black, channel black, graphite and the like can be used. Of these, furnace black is particularly preferable, and specific examples thereof include SAF, ISAF,
ISAF-HS, ISAF-LS, IISAF-HS,
Examples include grades such as HAF, HAF-HS, HAF-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 particularly limited.
However, the nitrogen adsorption specific surface area (N ₂SA), good
5 to 200 m²/ G, more preferably 50 m to 15
0m²/ G, particularly preferably 80 to 130 m²/ G
It If the nitrogen adsorption specific surface area is within this range, the tensile characteristics will be higher.
Excellent in performance. Also, the DBP adsorption amount of carbon black
Also, although not particularly limited, preferably 5 to 300 ml /
100 g, more preferably 50-200 ml / 100
g, particularly preferably 80 to 160 ml / 100 g
It If the DBP adsorption amount is in this range, the tensile properties will be improved.
Excel. Further, as carbon black, JP-A-5-
Cetyl trimethyl disclosed in Japanese Patent No. 230290
Adsorption (CTAB) specific surface area of ammonium bromide
110-170m²/ G and 24,000 psi
DBP (24M4 after compressing repeatedly four times with pressure)
DBP) oil absorption is 110-130 ml / 100 g
By using high structure carbon black
Wear resistance can be improved.

The amount of the reinforcing agent blended is preferably 10 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 silica and carbon black are used together as a reinforcing agent, the mixing ratio is a weight ratio of silica: carbon black of preferably 10:90 to 99: 1, more preferably 30:70 to 95: 5, and particularly preferably. 5
It is 0:50 to 90:10.

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 buildup. Examples of the silane coupling agent include vinyltriethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, N-
(Β-aminoethyl) -γ-aminopropyltrimethoxysilane, bis (3- (triethoxysilyl) propyl) tetrasulfide, bis (3- (triethoxysilyl) propyl) disulfide, and the like, JP-A-6-248.
.Gamma.-trimethoxysilylpropyldimethylthiocarbamyl tetrasulfide, .gamma.
Examples thereof include tetrasulfides such as trimethoxysilylpropylbenzothiazyltetrasulfide. Since scorch at the time of kneading can be avoided, the silane coupling agent preferably has 4 or less sulfur contained in one molecule. These silane coupling agents are
Each can be used alone or in combination of two or more.

The compounding 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 with respect to 100 parts by weight of silica.
10 to 10 parts by weight.

The rubber composition of the present invention may contain a rubber other than the conjugated diene rubber of the present invention within a range not substantially impairing the effects of the present invention. Examples of other rubbers include natural rubber, high cis-polyisoprene rubber, high cis-polybutadiene rubber, acrylonitrile-butadiene copolymer rubber, butyl rubber, ethylene-propylene-diene copolymer rubber and the like.

In the rubber composition of the present invention, in addition to the above-mentioned components, a crosslinking agent, a crosslinking accelerator, a crosslinking activator, an antiaging agent, an activator, a plasticizer, a lubricant, a filler and the like are compounded according to a conventional method. Each agent can be contained in the required amount.

Examples of the crosslinking agent include sulfur such as powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, and highly dispersible sulfur; sulfur halide such as sulfur monochloride and sulfur dichloride;
Organic peroxides such as dicumyl peroxide and ditertiary butyl peroxide; p-quinone dioxime, p,
Quinonedioximes such as p′-dibenzoylquinonedioxime; organic polyvalent amine compounds such as triethylenetetramine, hexamethylenediamine carbamate and 4,4′-methylenebis-o-chloroaniline; alkylphenol resins having methylol groups; And so on.
Among these, sulfur is preferable, and powdered sulfur is particularly preferable. These crosslinking agents may be used alone or in combination with
Used in combination of two or more species. The blending amount of the cross-linking agent is
It is preferably 0.3 to 1 with respect to 100 parts by weight of the rubber component.
It is 0 part by weight, more preferably 0.5 to 5 parts by weight.

As the crosslinking accelerator, N-cyclohexyl-2-benzothiazolesulfenamide, Nt-butyl-2-benzothiazolesulfenamide, N-oxyethylene-2-benzothiazolesulfenamide, N- Sulfenamide-based crosslinking accelerators such as oxyethylene-2-benzothiazole sulfenamide and N, N'-diisopropyl-2-benzothiazole sulfenamide; guanidines such as diphenylguanidine, diortotolylguanidine, orthotolylbiguanidine -Based cross-linking accelerators; thiourea-based cross-linking accelerators such as diethylthiourea; thiazole-based cross-linking accelerators such as 2-mercaptobenzothiazole, dibenzothiazyl disulfide, and 2-mercaptobenzothiazole zinc salt; tetramethylthiuram monosulfi And tetramethylthiuram disulfide and other thiuram crosslinking accelerators; sodium dimethyldithiocarbamate, zinc diethyldithiocarbamate and other dithiocarbamic acid crosslinking accelerators; sodium isopropylxanthate, zinc isopropylxanthate, zinc butylxanthogenate and other xanthates. Crosslinking accelerators such as a system crosslinking accelerator; These cross-linking accelerators may be used alone or in combination of two or more, but those containing a sulfenamide-based cross-linking accelerator are preferable. The amount of the crosslinking accelerator compounded is preferably 0.3 with respect to 100 parts by weight of the rubber component.
10 to 10 parts by weight, more preferably 0.5 to 5 parts by weight.

As the crosslinking activator, for example, higher fatty acids such as stearic acid and zinc oxide can be used. As the zinc oxide, it is preferable to use one having a high surface activity and a particle size of 5 μm or less, and a particle size of 0.05 to 0.
Examples include 2 μm active zinc white and 0.3 to 1 μm zinc white. Zinc oxide may be surface-treated with an amine-based dispersant or a wetting agent. These cross-linking activators can be used alone or in combination of two or more. The mixing ratio of the cross-linking activator is
It is appropriately selected depending on the type of crosslinking activator. The amount of the higher fatty acid compounded 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. The content of zinc oxide is preferably 0.1 to 5 parts by weight, more preferably 0.5 to 2 parts by weight, based on 100 parts by weight of the rubber component.

Examples of the compounding agents include activators such as diethylene glycol, polyethylene glycol and silicone oil; fillers such as calcium carbonate, talc, clay and aluminum hydroxide; waxes and the like.

The rubber composition containing the reinforcing agent can be obtained by kneading the respective components in a conventional manner. For example, a rubber composition can be obtained by kneading a compounding agent excluding a crosslinking agent and a crosslinking accelerator, a reinforcing agent, and a rubber component, and then kneading the kneaded product with the crosslinking agent and the crosslinking accelerator. The kneading temperature of the compounding agent excluding the cross-linking agent and the cross-linking accelerator, the reinforcing agent, and the rubber component is preferably 80 to 200 ° C, more preferably 100 to 19 ° C.
The temperature is 0 ° C., particularly preferably 140 to 180 ° C.
Then, the obtained kneaded product is preferably 100 ° C. or lower,
More preferably, after cooling to 80 ° C. or less, it is kneaded with a crosslinking agent and a crosslinking accelerator. Further, the rubber composition containing a reinforcing agent can be obtained as a wet masterbatch rubber by previously mixing the polymer latex before being obtained as a solid rubber with a reinforcing agent in a predetermined ratio.

The rubber composition of the present invention is usually used after being crosslinked. The cross-linking method is not particularly limited, and may be selected according to the shape and size of the cross-linked product. The mold may be filled with the crosslinkable rubber composition and heated to be crosslinked at the same time as the molding, or the premolded crosslinkable rubber composition may be heated and crosslinked. 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 120-200.
C., more preferably 140 to 180.degree.

The rubber composition of the present invention is used for various applications making good use of its properties, for example, tire members such as treads, undertreads, carcasses, sidewalls and beads.
Rubber members such as hoses, window frames, belts, shoe soles, anti-vibration rubber, seismic isolation rubber, and automobile parts; impact-resistant polystyrene, AB
It can be used as a resin-reinforced rubber member such as S resin. Among them, it is suitable as a tire member, and particularly suitable as a tire tread for a fuel-efficient tire.

[0068]

EXAMPLES The present invention will be described in detail below with reference to examples. The parts and% in the examples and comparative examples are based on weight unless otherwise specified.

(1) Amount of styrene unit in copolymer: JI
It was measured according to SK6383 (refractive index method). (2) Amino group-containing monomer unit amount in the copolymer: The copolymer is dissolved in tetrahydrofuran, reprecipitation purification is performed twice with a mixed solvent of methanol / acetone (1/1 volume ratio), and vacuum drying is performed. Then, it was measured by 500 MHz ¹ H-NMR.

(3) Amount of epoxy group-containing monomer unit in the copolymer: The copolymer is dissolved in tetrahydrofuran, and reprecipitation purification is performed twice with a methanol / acetone (1/1 volume ratio) mixed solvent. The sample dried in vacuum was used as a sample. Dissolve the sample in tetrahydrofuran, and add an excess of 0.01N hydrochloric acid-acetone solution (in a 0.1N hydrochloric acid aqueous solution,
A mixture of acetone to give a 0.01N hydrochloric acid-acetone solution) is added and reacted with the epoxy groups in the copolymer, and the amount of hydrochloric acid remaining unreacted is 0.01N alcohol. The amount of epoxy group in the copolymer was calculated by titrating with an aqueous potassium hydroxide solution to obtain the amount of epoxy group-containing monomer unit. (4) Mooney viscosity (ML _{1 + 4} , 100 ° C): JIS
It was measured according to K6300. (5) Tensile property: 300% according to JIS K6301
The stress at extension (MPa) was measured. This property is indicated by an index (tensile property index) with the reference sample being 100. The larger this value is, the more preferable. (6) Low heat build-up: RDA-II manufactured by Rheometrics
Was used to measure tan δ at 60 ° C. under the condition of 0.5% twist and 20 Hz. This characteristic is indicated by an index (low exothermic index) with 100 as a reference sample. The larger this value is, the more preferable.

(7) Workability: After roll kneading, a sheet-shaped sample taken out so that the thickness of the sheet was 3 mm was observed, and the smoothness of the surface skin and the continuity of the edge portion of the sheet were evaluated according to the following criteria. Was scored and judged by the total score. The larger the total score is, the better the workability is. If the total score is 5 or more, no problem occurs in a post-process such as a green tire molding process. Surface smoothness 4 points: The surface is smooth and glossy. 3 points: The surface is almost smooth, but there is no gloss. 2 points: There are irregularities. 1 point: There are many irregularities and the depth of the irregularities is deep. Edge continuity 4 points: smooth. 3 points: There are some irregularities. 2 points: There are many irregularities. 1 point: There are many deep cuts.

(Preliminary experiment) 200 parts of deionized water, 2 parts of rosin acid soap, 2.1 parts of fatty acid soap were placed in a pressure resistant reactor equipped with a stirrer.
Part, 1,3-butadiene 56.8 parts, styrene 42.5
Parts and 0.16 parts of t-dodecyl mercaptan. The reactor temperature was set to 8 ° C., 0.1 part of diisopropylbenzene hydroperoxide as a polymerization initiator, and 0.2 of sodium formaldehyde sulfoxylate.
5 parts by weight of a deionized aqueous solution, 0.004 parts of sodium ethylenediaminetetraacetate and 0.2 parts of ferric sulfate.
Polymerization was started by adding 2 parts of a deionized aqueous solution containing 04 parts and 04 parts to a reactor. When the polymerization conversion rate in the polymerization system reached 45%, 0.05 part of diethylhydroxylamine was added to 100 parts of the polymer to stop the reaction.
After removing unreacted monomers from the obtained polymer latex by steam distillation, octadecyl-3- (3,5-di-t) was added to 100 parts of the polymer as an antioxidant.
0.8 part of -butyl-4-hydroxyphenyl) propionate and 0.2 part of 2,4-bis (n-octylthiomethyl) -6-methylphenol were added. While adjusting the pH to 3 to 5 with sulfuric acid, the polymer latex was coagulated with sodium chloride to obtain a crumb-shaped polymer. This 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 confirmed to be in the range of 70 to 200.

(Example 1) In a pressure resistant reactor equipped with a stirrer, 200 parts of deionized water, 2 parts of rosin acid soap, and 2.1 parts of fatty acid soap.
Part, the monomer having the initial charging composition shown in Table 1 and t-dodecyl mercaptan were charged. The reactor temperature was set to 8 ° C., 5 parts of a deionized aqueous solution in which 0.1 part of diisopropylbenzene hydroperoxide and 0.2 part of sodium formaldehyde sulfoxylate were dissolved as a polymerization initiator,
And sodium ethylenediaminetetraacetate 0.004
And 2 parts of a deionized aqueous solution in which 0.04 part of ferric sulfate was dissolved were added to the reactor to initiate polymerization. When the polymerization conversion rate in the polymerization system reached 45%, a part of the polymer latex in the polymerization system was extracted and the polymer 100 contained therein was extracted.
The reaction was stopped by adding 0.05 parts of diethylhydroxylamine to the parts. Immediately after the polymer latex was extracted during the reaction, the polar group-containing monomer and t-dodecyl mercaptan were added to the polymerization reaction system in the amount ratio shown in the post-addition composition in Table 1 to continue the polymerization reaction. Let At the time when the polymerization conversion rate in the polymerization system reached 70%, diethylhydroxylamine was added in an amount of 0.0 to 100 parts of the polymer.
The reaction was stopped by adding 5 parts.

After the unreacted monomer was removed from the latex extracted during the reaction by steam distillation, the polymer 1
To 00 parts, as an anti-aging agent, octadecyl-3
0.8 parts of-(3,5-di-t-butyl-4-hydroxyphenyl) propionate and 2,4-bis (n-
0.2 part of octylthiomethyl) -6-methylphenol was added. This was coagulated with sodium chloride while adjusting the pH to 3 to 5 with sulfuric acid to obtain a crumb-shaped polymer. This crumb was dried with a hot air dryer at 80 ° C. to obtain a solid rubber. Table 1 shows the Mooney viscosity of the polymer in the extracted latex.

From the polymer latex finally obtained,
After removing the unreacted monomers by steam distillation, octadecyl-
0.8 parts of 3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate and 2,4-bis (n-
Octylthiomethyl) -6-methylphenol (0.2 part) was added to obtain a polymer latex of the conjugated diene rubber A. 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-shaped polymer. This crumb was dried with a hot air dryer at 80 ° C. to obtain a conjugated diene rubber A. Table 1 shows the composition and Mooney viscosity of the obtained rubber.

A polymer latex of a conjugated diene rubber A was used as an extender oil with 100 parts of the entire polymer.
37.5 parts of thene 1849A (manufactured by British Petroleum) was added. After that, pH 3-5 with sulfuric acid
The polymer latex containing the extender oil was coagulated with sodium chloride while preparing so as to obtain a crumb-shaped solid. Dry this crumb with a hot air dryer at 80 ° C,
An oil-extended rubber was obtained. The Mooney viscosity of the obtained oil-extended rubber is shown in Table 1.

Using a Brabender type mixer, 137.5 parts of the above oil-extended rubber (corresponding to 100 parts of rubber).
Was masticated at a starting temperature of 110 ° C. for 30 seconds, and then silica (Zeosil 1165MP: manufactured by Rhodia) 53
And 6.4 parts of a silane coupling agent (Si69: manufactured by Degussa) were added and kneaded for 2 minutes, and then silica (Z
eosil 1165MP: manufactured by Rhodia) 27 parts,
3 parts of zinc oxide (particle size 0.4 μm, zinc flower # 1: manufactured by Honjo Chemical Co., Ltd.), 2 parts of stearic acid, and 2 parts of antioxidant (Nocrac 6C: manufactured by Ouchi Shinko Co., Ltd.) were added and kneaded for 2 minutes. . The temperature at the end of kneading was 150 ° C.

The resulting kneaded product, 1.4 parts of sulfur, 1.8 parts of a crosslinking accelerator (N-cyclohexyl-2-benzothiazylsulfenamide and 1.8 parts of diphenylguanidine) were used.
Part of the mixture) was kneaded with an open roll at 50 ° C., and then taken out as a sheet. The workability was scored by observing the surface skin and the edge portion of the above-mentioned sheet. The results are shown in Table 1. Regarding the physical properties of the crosslinked rubber, press-crosslinking was performed at 160 ° C. for 30 minutes to prepare a test piece, and each physical property was measured. The results are shown in Table 1. However, in Table 1, the stress at 300% elongation and tan δ are based on Comparative Example 2 (index 100).
Notated as

(Examples 2 and 3) The same procedure as in Example 1 was carried out except that the initial charge composition and the post-addition composition shown in Table 1 were changed. The results are shown in Table 1.

(Examples 4 and 5) The initial charging composition and the post-addition composition shown in Table 1 were changed, and the conditions for coagulating the polymer latex were adjusted to pH 7 except that calcium chloride was used. The same procedure as in Example 1 was performed. The results are shown in Table 1.

(Comparative Examples 1 to 4) The same procedure as in Example 1 was carried out except that the initial charge composition and the post-addition composition shown in Table 1 were changed. The results are shown in Table 1.

[0082]

[Table 1]

The following can be seen from Table 1. The silica-containing rubber composition of Comparative Example 1 using the conjugated diene rubber F that does not use the polar group-containing monomer is excellent in processability, but inferior in tensile properties and low heat buildup. 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 initiation of polymerization is superior to Comparative Example 1 in tensile properties and low heat buildup. However, it is inferior in workability.

Although the polar group-containing monomer was added during the polymerization, the difference in Mooney viscosity between the polymer present in the reaction system at the time of addition and the finally obtained conjugated diene rubber was The silica-blended rubber composition of Comparative Example 3 using the conjugated diene rubber H outside the range specified in the invention is inferior in processability, and inferior in tensile properties and low heat buildup. Although the polar group-containing monomer was added during the polymerization, the silica-containing rubber composition of Comparative Example 4 using the conjugated diene rubber J whose addition rate in the initial charging is larger than the range specified in the present invention is , Tensile properties and low heat buildup are comparable,
Inferior in workability.

Compared to these comparative examples, Example 1 using the conjugated diene rubbers A to E within the range specified in the present invention was used.
The silica-containing rubber compositions Nos. 5 to 5 have excellent processability, tensile properties and low heat buildup.

[0086]

EFFECTS OF THE INVENTION According to the present invention, a conjugated diene-based compound which is excellent in the surface shape of a sheet when a mixture containing silica as a reinforcing agent is formed into a sheet by a roll, and is excellent in tensile properties and low heat buildup. Rubbers, oil extended rubbers and rubber compositions are provided.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C08L 9/00 C08L 9/00 F term (reference) 4J002 AC02W AC03W AC08W AC09W AE05X BC05W BC08W BC09W BC11W DJ016 FD010 FD016 GN01 4J011 AA05 AA07 BA04 BB01 BB06 BB09 BB12 BB17 KB09 KB13 KB14 KB29 4J100 AB02Q AL10R AM19R AS02P CA05 CA25 DA09 DA49 FA03 FA20 JA29

Claims (8)

[Claims] 1. Conjugated diene monomer unit 40 to 99.9% by weight, aromatic vinyl monomer unit 0 to 59.9% by weight and polar group-containing monomer unit 0.1 to 20% by weight. ,
A conjugated diene rubber having a Mooney viscosity (M1) of 20 to 150, which comprises at least a part of a conjugated diene monomer used for polymerization, at least a part of an aromatic vinyl monomer and a polar group-containing monomer. Polymerization of a monomer mixture containing less than 30% by weight is started, 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, and a polar group is contained. The Mooney viscosity (M2) of the polymer in the reaction system of the remainder of the monomer and the molecular weight modifier is 70 to
A conjugated diene rubber, which is obtained by continuously adding and adding while being in the range of 200 (however, M1 is lower than M2 by 5 or more). 2. The conjugated diene rubber according to claim 1, wherein the polymerization is emulsion polymerization. 3. The amount of the polymer produced in the reaction system when the balance of the polar group-containing monomer is added is 20 to 80% by weight based on the total amount of the conjugated diene rubber obtained by the polymerization. 1. The conjugated diene rubber according to 1. 4. The conjugated diene rubber according to claim 1, wherein the polar group-containing monomer is an amino group-containing monomer or an epoxy group-containing monomer. 5. An oil-extended rubber comprising the conjugated diene rubber according to claim 1 and an extender oil. 6. A rubber composition containing the conjugated diene rubber according to claim 1. 7. A rubber composition containing the oil-extended rubber according to claim 5. 8. The rubber composition according to claim 6, which contains silica as an essential component.