阅读说明：本技术 共轭二烯系橡胶 (Conjugated diene rubber ) 是由 樱井拓郎 饭冢崇 藤井真 滨久胜 于 2018-09-28 设计创作，主要内容包括：本发明提供一种共轭二烯系橡胶,其具有以异戊二烯单体单元为主成分的聚合物嵌段(A)和以1,3-丁二烯单体单元为主成分的聚合物嵌段(B),上述聚合物嵌段(A)和上述聚合物嵌段(B)中至少一者包含含有能与二氧化硅相互作用的官能团的乙烯基化合物的单元,上述聚合物嵌段(A)的重均分子量(Mw)为1000～30000的范围,上述共轭二烯系橡胶总体的重均分子量(Mw)为50000～5000000的范围。(The present invention provides a conjugated diene rubber comprising a polymer block (A) containing isoprene monomer units as a main component and a polymer block (B) containing 1, 3-butadiene monomer units as a main component, wherein at least one of the polymer block (A) and the polymer block (B) contains a unit of a vinyl compound having a functional group capable of interacting with silica, the weight average molecular weight (Mw) of the polymer block (A) is in the range of 1000 to 30000, and the weight average molecular weight (Mw) of the entire conjugated diene rubber is in the range of 50000 to 5000000.)

1. A conjugated diene rubber comprising a polymer block A mainly composed of isoprene monomer units and a polymer block B mainly composed of 1, 3-butadiene monomer units,

at least one of the polymer block A and the polymer block B contains a vinyl compound unit containing a functional group capable of interacting with silica,

the weight average molecular weight Mw of the polymer block A is in the range of 1000 to 30000, and the weight average molecular weight Mw of the entire conjugated diene rubber is in the range of 50000 to 5000000.

2. The conjugated diene rubber according to claim 1, wherein the content ratio of the vinyl compound unit having a functional group capable of interacting with silica is 0.01 to 20% by weight based on the total monomer units constituting the conjugated diene rubber.

3. The conjugated diene rubber according to claim 1 or 2, wherein at least one of the polymer block a and the polymer block B contains an aromatic vinyl monomer unit.

4. The conjugated diene rubber according to any one of claims 1 to 3, wherein the polymer block B has a functional group containing a hetero atom at a terminal thereof.

5. A method for producing the conjugated diene rubber according to any one of claims 1 to 4, comprising:

a step of polymerizing a monomer a containing isoprene in an inert solvent using a polymerization initiator to form a polymer block A having an active end; and

mixing the polymer block A having an active end with a monomer B containing 1, 3-butadiene, and continuing the polymerization reaction to obtain a conjugated diene polymer chain having an active end and having a polymer block A and a polymer block B;

at least one of the monomer a or the monomer b contains a vinyl compound containing a functional group capable of interacting with silica.

6. The method for producing a conjugated diene rubber according to claim 5, further comprising a step of reacting a heteroatom-containing compound with the active end of the conjugated diene polymer chain having an active end.

7. A rubber composition comprising a rubber component and silica, wherein the rubber component comprises the conjugated diene rubber according to any one of claims 1 to 4.

8. The rubber composition according to claim 7, further comprising a crosslinking agent.

9. A crosslinked rubber product obtained by crosslinking the rubber composition according to claim 7 or 8.

10. A tire comprising the rubber conjugate of claim 9.

Technical Field

The present invention relates to a conjugated diene rubber, and more particularly, to a conjugated diene rubber which can effectively suppress adhesion to a roller when a rubber composition is prepared, and can form a rubber crosslinked product having excellent low heat generation properties and handling stability.

Background

In recent years, in view of environmental problems and resource problems, low fuel consumption has been strongly demanded for tires for automobiles. A crosslinked product of a rubber composition containing silica as a filler in a rubber is excellent in low heat build-up property as compared with a crosslinked product of a rubber composition containing carbon black, and therefore, rolling resistance is reduced when a tire is formed. Therefore, a tire having excellent fuel economy can be obtained by using a rubber crosslinked material formed from a rubber composition containing silica.

In the rubber constituting such a rubber composition, various attempts have been made to improve the affinity between the rubber and silica. For example, patent document 1 discloses the following technique: in obtaining a rubber polymer by a solution polymerization method, a specific polymerization initiator is used to polymerize monomer components including a conjugated diene compound and a silicon-containing vinyl compound, thereby imparting affinity with silica to the rubber itself.

Disclosure of Invention

Problems to be solved by the invention

On the other hand, in view of recent increasing demands for performance of automobile tires, in tires newly developed in the future, there is a need for a rubber crosslinked material that can be formed with lower heat generation properties more excellent than those in the case of using known rubbers such as the rubber described in patent document 1.

The present invention has been made in view of the above problems, and an object thereof is to provide a conjugated diene rubber which can effectively suppress adhesion to a roller when a rubber composition is produced, and which can form a crosslinked rubber product having excellent low heat generation properties and handling stability.

Means for solving the problems

The present inventors have conducted intensive studies in order to achieve the above object, and as a result, have found that the above object can be achieved by providing a conjugated diene rubber having a polymer block mainly composed of isoprene monomer units and having a weight average molecular weight (Mw) within a specific range and a polymer block mainly composed of 1, 3-butadiene monomer units, and including a vinyl compound unit containing a functional group capable of interacting with silica in at least one of the polymer blocks, and have completed the present invention.

That is, according to the present invention, there is provided a conjugated diene rubber comprising a polymer block (a) containing isoprene monomer units as a main component and a polymer block (B) containing 1, 3-butadiene monomer units as a main component, wherein at least one of the polymer block (a) and the polymer block (B) contains a vinyl compound unit containing a functional group capable of interacting with silica, the weight average molecular weight (Mw) of the polymer block (a) is in the range of 1000 to 30000, and the weight average molecular weight (Mw) of the entire conjugated diene rubber is in the range of 50000 to 5000000.

In the conjugated diene rubber of the present invention, the content ratio of the vinyl compound unit having a functional group capable of interacting with silica is preferably 0.01 to 20% by weight based on the total monomer units constituting the conjugated diene rubber.

In the conjugated diene rubber of the present invention, at least one of the polymer block (a) and the polymer block (B) preferably contains an aromatic vinyl monomer unit.

The conjugated diene rubber of the present invention preferably has a functional group containing a hetero atom at the terminal of the polymer block (B).

According to the present invention, there is provided a method for producing a conjugated diene rubber, which is any one of the above-described methods for producing a conjugated diene rubber, comprising the steps of: a step of polymerizing a monomer (a) containing isoprene in an inert solvent using a polymerization initiator to form a polymer block (A) having an active end; and a step of mixing the polymer block (a) having an active end with a monomer (B) containing 1, 3-butadiene, and continuing the polymerization reaction to obtain a conjugated diene polymer chain having an active end and having the polymer block (a) and the polymer block (B); at least one of the monomer (a) and the monomer (b) contains a vinyl compound having a functional group capable of interacting with silica.

The method for producing a conjugated diene rubber of the present invention preferably further comprises a step of reacting a heteroatom-containing compound with the active end of the conjugated diene polymer chain having an active end.

Further, according to the present invention, there can be provided a rubber composition containing a rubber component containing any one of the above-described conjugated diene rubbers and silica.

The rubber composition of the present invention preferably further contains a crosslinking agent.

Further, the present invention can provide a crosslinked rubber product obtained by crosslinking the rubber composition, and a tire comprising the crosslinked rubber product.

Effects of the invention

According to the present invention, there can be provided a conjugated diene rubber which can effectively suppress adhesion to a roller when a rubber composition is produced, and which can form a crosslinked rubber product having excellent low heat generation properties and excellent handling stability. Further, according to the present invention, a method for producing such a conjugated diene rubber, and a rubber composition, a rubber crosslinked product, and a tire using such a conjugated diene rubber can also be provided.

Detailed Description

< conjugated diene rubber >

The conjugated diene rubber of the present invention comprises a polymer block (A) containing isoprene monomer units as the main component and a polymer block (B) containing 1, 3-butadiene monomer units as the main component,

at least one of the polymer block (A) and the polymer block (B) contains a vinyl compound unit containing a functional group capable of interacting with silica,

the weight average molecular weight (Mw) of the polymer block (A) is in the range of 1000 to 30000, and the weight average molecular weight (Mw) of the entire conjugated diene rubber is in the range of 50000 to 5000000.

According to the conjugated diene rubber of the present invention, adhesion to a roller can be effectively suppressed when the conjugated diene rubber is used as a rubber composition, and a crosslinked rubber having excellent low heat generation properties and excellent handling stability can be formed.

In particular, the present inventors have conducted intensive studies to further improve the low heat build-up property in view of recent increasing demands for the performance of automobile tires, and as a result, have found that the affinity for fillers such as silica can be further improved by providing a conjugated diene rubber with a polymer block (a) containing isoprene monomer units as a main component and having a weight average molecular weight (Mw) within a specific range and a polymer block (B) containing 1, 3-butadiene monomer units as a main component, and including a vinyl compound unit containing a functional group capable of interacting with silica in at least one of the polymer blocks, whereby the low heat build-up property can be further improved, and further, not only the low heat build-up property is excellent, but also the operational stability is excellent. In particular, it is considered that the handling stability can be improved by sufficiently exhibiting the reinforcing property of the filler such as silica, and it is considered that the reinforcing property by the filler such as silica can be sufficiently exhibited by adopting the above-described structure.

Further, the present inventors have made intensive studies in addition to the above, and as a result, have found an unexpected effect completely different from the improvement of the low heat generation property, the effect being: when the conjugated diene rubber of the present invention having the above-described structure is compounded with a filler such as silica to prepare a rubber composition, adhesion to a roller can be effectively suppressed when the rubber composition is processed into a sheet shape or the like by using a roller. In particular, when the rubber composition is processed into a sheet or the like using a roller, adhesion to the roller can be effectively suppressed, and further excellent processability can be achieved.

The polymer block (a) may be a polymer block having an isoprene monomer unit as a main component, and is not particularly limited, and may contain only an isoprene monomer unit, or may contain an isoprene monomer unit and a monomer unit other than an isoprene monomer unit. In this case, the monomer unit other than the isoprene monomer unit is preferably an aromatic vinyl monomer unit, and the polymer block (a) of the present invention preferably contains an aromatic vinyl monomer unit in addition to the isoprene monomer unit.

The content ratio of the isoprene monomer units in the polymer block (a) is preferably 50% by weight or more, more preferably 70% by weight or more, and further preferably 90% by weight or more. The upper limit of the content ratio of the isoprene monomer unit is not particularly limited, and is preferably 99% by weight or less. When the content ratio of the isoprene monomer units in the polymer block (a) is in the above range, the affinity between the conjugated diene rubber and the compounding agent such as silica can be further improved when the compounding agent such as silica is compounded to the conjugated diene rubber, and thus the low heat generation property of the obtained rubber crosslinked product can be further improved.

Examples of the aromatic vinyl compound used for forming the aromatic vinyl monomer unit include styrene, methylstyrene, ethylstyrene, t-butylstyrene, α -methylstyrene, α -methyl-p-methylstyrene, chlorostyrene, bromostyrene, methoxystyrene, dimethylaminomethylstyrene, dimethylaminoethylstyrene, diethylaminomethylstyrene, diethylaminoethylstyrene, cyanoethylstyrene, and vinylnaphthalene. Among them, styrene is preferred. The content ratio of the aromatic vinyl monomer unit in the polymer block (a) is preferably 50% by weight or less, more preferably 30% by weight or less, and still more preferably 10% by weight or less. The lower limit of the content of the aromatic vinyl monomer unit is not particularly limited, and is preferably 1% by weight or more.

In the conjugated diene rubber of the present invention, at least one of the polymer block (a) and the polymer block (B) described later contains a vinyl compound unit containing a functional group capable of interacting with silica. Although the case where the polymer block (a) contains such a vinyl compound unit having a functional group capable of interacting with silica is described below as an example, at least one of the polymer block (a) and the polymer block (B) described later may contain such a vinyl compound unit having a functional group capable of interacting with silica, and therefore, when the polymer block (B) described later contains a vinyl compound unit having a functional group capable of interacting with silica, it is not necessary to include the unit in the polymer block (a).

The vinyl compound having a functional group capable of interacting with silica, which is used to form a vinyl compound unit having a functional group capable of interacting with silica, is not particularly limited as long as it is a compound having a functional group capable of interacting with silica and a vinyl group. Here, the functional group capable of interacting with silica means a functional group capable of forming a covalent bond between the functional group and the silica surface, or a functional group capable of forming an intermolecular interaction force weaker than the covalent bond (for example, ion-dipole interaction, dipole-dipole interaction, hydrogen bond, van der waals force, or the like). Such a functional group capable of interacting with silica is not particularly limited, and a functional group containing a nitrogen atom, a functional group containing a silicon atom, a functional group containing an oxygen atom, and the like are exemplified, and among them, a functional group containing a silicon atom is preferable from the viewpoint of strong interaction with silica.

As the vinyl compound having a functional group containing a silicon atom, which is a preferred embodiment among the vinyl compounds having a functional group capable of interacting with silica, for example, a compound represented by the following general formula (1) can be preferably used.

[ chemical formula 1]

In the above general formula (1), X¹Represents a single chemical bond or an alkylene group, X²、X³And X⁴Each independently represents a substituted amino group, a hydrocarbyloxy group, or a hydrocarbon group which may have a substituent.

In the above general formula (1), X¹Is a single chemical bond or alkylene group, preferably a single chemical bond. Examples of the alkylene group include an alkylene group, an alkenyldiyl group, an arylene group, and a group in which an arylene group is bonded to an alkylene group.

Examples of the alkylene group include a methylene group, an ethylene group, and a trimethylene group. Examples of the alkenyldiyl group include a vinylene group and an ethylene-1, 1-diyl group. Examples of the arylene group include a phenylene group, a naphthylene group, and a biphenylene group. Examples of the group in which an arylene group is bonded to an alkylene group include a group in which a phenylene group is bonded to a methylene group, and a group in which a phenylene group is bonded to an ethylene group. At X¹In the case of alkylene, X¹Preferably an arylene group, more preferably a phenylene group.

In the above general formula (1), X²、X³And X⁴Each independently representA substituted amino group, a hydrocarbyloxy group, or a hydrocarbon group which may have a substituent. Preferably X²、X³And X⁴At least 1 of which is a substituted amino group, more preferably X²、X³And X⁴2 of which are substituted amino groups.

As can constitute X²、X³And X⁴The substituted amino group of (3) is preferably a group represented by the following general formula (2).

[ chemical formula 2]

In the above general formula (2), R¹And R²May or may not be bonded to each other at R¹And R²In the case of not being bonded to each other, R¹And R²Each independently represents a hydrocarbon group which may have a substituent, or a trihydrocarbylsilyl group at R¹And R²In the case of bonding to each other, R¹And R²Represents an alkylene group which may contain a nitrogen atom and/or an oxygen atom.

As can constitute R¹And R²Examples of the hydrocarbyl group of (b) include chain alkyl groups such as a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a n-pentyl group, a n-hexyl group, and a n-octyl group; cyclic alkyl groups such as cyclopentyl and cyclohexyl; and aryl groups such as phenyl, benzyl, and naphthyl. Among them, a chain alkyl group is preferable, and a methyl group or an ethyl group is more preferable.

Can form R¹And R²When the hydrocarbon group of (a) has a substituent, examples thereof include a hydrocarbon group having a hydrocarbyloxy group as a substituent, and examples thereof include an alkoxyalkyl group such as a methoxymethyl group, an ethoxymethyl group, or a methoxyethyl group; aryloxyalkyl groups such as phenoxymethyl.

As can constitute R¹And R²Specific examples of the trihydrocarbylsilyl group (b) include trialkylsilyl groups such as a trimethylsilyl group, a triethylsilyl group, and a t-butyldimethylsilyl group.

At R¹And R²When bonded to each other, R is a constitutional unit¹And R²Examples of the alkylene group of (a) include alkylene groups such as trimethylene group, tetramethylene group, pentamethylene group, hexamethylene group, heptamethylene group, octamethylene group, decamethylene group, dodecamethylene group, and 2,2, 4-trimethylhexane-1, 6-diyl group; an enediyl group such as pentane-2-ene-1, 5-diyl, and the like. In addition, R may be constituted¹And R²When the alkylene group of (a) contains a nitrogen atom and/or an oxygen atom, examples of the alkylene group containing a nitrogen atom and/or an oxygen atom include a group represented by-CH ═ N-CH ═ CH-, and a group represented by-CH ═ N-CH ═₂-CH₂A group represented by-CH₂-CH₂-O-CH₂-CH₂A group represented by the formula (II) or the like.

Preferably R¹And R²Is alkyl, or R¹And R²Alkylene groups bonded to each other, more preferably R¹And R²Is alkyl, more preferably R¹And R²Is methyl or ethyl.

In the above general formula (2), in R¹And R²In the case of a hydrocarbon group, specific examples of the group represented by the above general formula (2) include dialkylamino groups such as dimethylamino, diethylamino, ethylmethylamino, di-n-propylamino, diisopropylamino, di-n-butylamino, diisobutylamino, di-sec-butylamino, and di-tert-butylamino; diarylamino groups such as diphenylamino groups, and the like. Among them, a dialkylamino group is preferable, and a dimethylamino group, a diethylamino group, or a di-n-butylamino group is more preferable.

In the above general formula (2), in R¹And R²In the case of a hydrocarbon group having a hydrocarbyloxy group as a substituent, specific examples of the group represented by the above general formula (2) include a di (alkoxyalkyl) amino group such as a di (methoxymethyl) amino group or a di (ethoxymethyl) amino group.

In the above general formula (2), in R¹And R²In the case of a trihydrocarbylsilyl group, specific examples of the group represented by the above general formula (2) include a bis (trimethylsilyl) amino group and a bis (tert-butyldimethylsilyl) amino groupSilyl group-containing amino groups such as silyl) amino groups and N-trimethylsilyl-N-methylamino groups.

In the above general formula (2), in R¹And R²When they are bonded to each other to form an alkylene group, specific examples of the group represented by the above general formula (2) include 1-alkylideneimino groups such as 1-trimethyleneimino group, 1-Pyrrolidino (Pyrrolidino) group, 1-Piperidino (Piperidino) group, 1-hexamethyleneimino group, 1-heptamethyleneimino group, 1-octamethyleneimino group, 1-decamethyleneimino group, and 1-dodecamethyleneimino group.

In the above general formula (2), in R¹And R²When alkylene groups containing a nitrogen atom and/or an oxygen atom are bonded to each other, specific examples of the group represented by the above general formula (2) include a 1-imidazolyl group, a 4, 5-dihydro-1-imidazolyl group, a morpholinyl group, and the like.

The group represented by the above general formula (2) is preferably a dialkylamino group or a 1-alkyleneimino group, more preferably a dialkylamino group, and yet more preferably a dimethylamino group, a diethylamino group, or a di-n-butylamino group.

In the above general formula (1), X is a constitutional X²、X³And X⁴Examples of the hydrocarbyloxy group of (a) include alkoxy groups such as a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, a sec-butoxy group, and a tert-butoxy group; aryloxy groups such as phenoxy and benzyloxy.

In the above general formula (1), X is a constitutional X²、X³And X⁴Examples of the hydrocarbyl group of (b) include an alkyl group such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, or a tert-butyl group; and aryl groups such as phenyl, 4-methyl-1-phenyl, and benzyl.

Can form X²、X³And X⁴When the hydrocarbon group of (3) has a substituent, examples of the hydrocarbon group having a hydrocarbyloxy group as a substituent include an alkoxyalkyl group such as a methoxymethyl group, an ethoxymethyl group, or an ethoxyethyl group.

In the above general formula (1), in X¹Is a chemical single bond, X²、X³And X⁴1 in is takenIn the case of an amino group, specific examples of the vinyl compound containing a functional group containing a silicon atom represented by the above general formula (1) include (dialkylamino) dialkylvinylsilanes such as (dimethylamino) dimethylvinylsilane, (ethylmethylamino) dimethylvinylsilane, (di-n-propylamino) dimethylvinylsilane, (diisopropylamino) dimethylvinylsilane, (dimethylamino) diethylvinylsilane, (ethylmethylamino) diethylvinylsilane, (di-n-propylamino) diethylvinylsilane, and (diisopropylamino) diethylvinylsilane; [ bis (trimethylsilyl) amino group]Dimethylvinylsilane, [ bis (tert-butyldimethylsilyl) amino]Dimethylvinylsilane, [ bis (trimethylsilyl) amino]Diethylvinylsilane, [ bis (tert-butyldimethylsilyl) amino]Bis (trialkylsilyl) amino groups such as diethylvinylsilane]A dialkylvinylsilane; (dialkylamino) di (alkoxyalkyl) vinylsilanes such as (dimethylamino) di (methoxymethyl) vinylsilane, (dimethylamino) di (methoxyethyl) vinylsilane, (dimethylamino) di (ethoxymethyl) vinylsilane, (diethylamino) di (methoxymethyl) vinylsilane, (diethylamino) di (methoxyethyl) vinylsilane, (diethylamino) di (ethoxymethyl) vinylsilane, and (diethylamino) di (ethoxyethyl) vinylsilane; and cyclic aminodialkylvinylsilane compounds such as pyrrolidinyldimethylvinylsilane, piperidinyldimethylvinylsilane, hexamethyleneiminodimethylvinylsilane, 4, 5-dihydroimidazolyldimethylvinylsilane, and morpholinodimethylvinylsilane.

In the above general formula (1), in X¹Is alkylene, X²、X³And X⁴When 1 of the two (C) groups is a substituted amino group, specific examples of the vinyl compound having a functional group containing a silicon atom represented by the above general formula (1) include (dimethylamino) dimethyl-4-vinylphenylsilane, (dimethylamino) dimethyl-3-vinylphenylsilane, (diethylamino) dimethyl-4-Vinylphenylsilane, (diethylamino) dimethyl-3-vinylphenylsilane, (di-n-propylamino) dimethyl-4-vinylphenylsilane, (di-n-propylamino) dimethyl-3-vinylphenylsilane, (di-n-butylamino) dimethyl-4-vinylphenylsilane, (di-n-butylamino) dimethyl-3-vinylphenylsilane, (dimethylamino) diethyl-4-vinylphenylsilane, (dimethylamino) diethyl-3-vinylphenylsilane, (diethylamino) diethyl-4-vinylphenylsilane, (diethylamino) diethyl-3-vinylphenylsilane, (di-n-propylamino) diethyl-4-vinylphenylsilane, di-n-propylamino) dimethyl-4-vinylphenylsilane, di-n-propylamino-3-vinylphenylsilane, di-n-propylamino-4-vinylphenylsilane, (dialkylamino) dialkylvinylphenylsilanes such as (di-n-propylamino) diethyl-3-vinylphenylsilane, (di-n-butylamino) diethyl-4-vinylphenylsilane, and (di-n-butylamino) diethyl-3-vinylphenylsilane.

In the above general formula (1), in X¹Is a chemical single bond, X²、X³And X⁴When 2 of them are substituted amino groups, specific examples of the vinyl compound having a functional group containing a silicon atom represented by the above general formula (1) include bis (dialkylamino) alkylvinylsilanes such as bis (dimethylamino) methylvinylsilane, bis (diethylamino) methylvinylsilane, bis (di-n-propylamino) methylvinylsilane, bis (di-n-butylamino) methylvinylsilane, bis (dimethylamino) ethylvinylsilane, bis (diethylamino) ethylvinylsilane, bis (di-n-propylamino) ethylvinylsilane, and bis (di-n-butylamino) ethylvinylsilane; bis [ bis (trimethylsilyl) amino]Methylvinylsilane, bis [ bis (tert-butyldimethylsilyl) amino]Methylvinylsilane, bis [ bis (trimethylsilyl) amino]Ethylvinylsilane, bis [ bis (tert-butyldimethylsilyl) amino]Bis [ bis (trialkylsilyl) amino group such as ethylvinylsilane]An alkylvinylsilane; bis (dimethylamino) methoxymethylvinylsilane, bis (dimethylamino) methoxyethylvinylsilane, bis (dimethylamino) ethoxymethylvinylsilane, bis (dimethylamino) ethoxyethylvinylsilane, bis (diethylamino) methoxyethylvinylsilaneBis (dialkylamino) alkoxyalkyl silanes such as hydroxymethylvinylsilane, bis (diethylamino) methoxyethylvinylsilane, bis (diethylamino) ethoxymethylvinylsilane, and bis (dimethylamino) ethoxyethylvinylsilane; bis (cyclic amino) alkylvinylsilane compounds such as bis (pyrrolidinyl) methylvinylsilane, bis (piperidino) methylvinylsilane, bis (hexamethyleneimino) methylvinylsilane, bis (4, 5-dihydroimidazolyl) methylvinylsilane, and bis (morpholino) methylvinylsilane.

In the above general formula (1), in X¹Is alkylene, X²、X³And X⁴When 2 of the amino groups are substituted, specific examples of the vinyl compound having a functional group containing a silicon atom represented by the above general formula (1) include bis (dimethylamino) methyl-4-vinylphenylsilane, bis (dimethylamino) methyl-3-vinylphenylsilane, bis (diethylamino) methyl-4-vinylphenylsilane, bis (diethylamino) methyl-3-vinylphenylsilane, bis (di-n-propylamino) methyl-4-vinylphenylsilane, bis (di-n-propylamino) methyl-3-vinylphenylsilane, bis (di-n-butylamino) methyl-4-vinylphenylsilane, bis (di-n-butylamino) methyl-3-vinylphenylsilane, bis (di-n-butylamino) methyl-, Bis (dialkylamino) alkylvinylphenylsilanes such as bis (dimethylamino) ethyl-4-vinylphenylsilane, bis (dimethylamino) ethyl-3-vinylphenylsilane, bis (diethylamino) ethyl-4-vinylphenylsilane, bis (diethylamino) ethyl-3-vinylphenylsilane, bis (di-n-propylamino) ethyl-4-vinylphenylsilane, bis (di-n-propylamino) ethyl-3-vinylphenylsilane, bis (di-n-butylamino) ethyl-4-vinylphenylsilane, and bis (di-n-butylamino) ethyl-3-vinylphenylsilane.

In the above general formula (1), in X¹Is a chemical single bond, X²、X³And X⁴When 3 of the above groups are substituted amino groups, specific examples of the vinyl compound having a functional group containing a silicon atom represented by the above general formula (1) include tris (dimethylamino) vinylsilane and tris (bis)And tris (dialkylamino) vinylsilanes such as ethylamino) vinylsilane, tris (di-n-propylamino) vinylsilane, and tris (di-n-butylamino) vinylsilane.

In the above general formula (1), in X¹Is alkylene, X²、X³And X⁴When 3 of the above groups are substituted amino groups, as a specific example of the vinyl compound having a functional group containing a silicon atom represented by the above general formula (1), examples thereof include tris (dialkylamino) vinylphenylsilanes such as tris (dimethylamino) -4-vinylphenylsilane, tris (dimethylamino) -3-vinylphenylsilane, tris (diethylamino) -4-vinylphenylsilane, tris (diethylamino) -3-vinylphenylsilane, tris (di-n-propylamino) -4-vinylphenylsilane, tris (di-n-propylamino) -3-vinylphenylsilane, tris (di-n-butylamino) -4-vinylphenylsilane, and tris (di-n-butylamino) -3-vinylphenylsilane.

In the above general formula (1), in X¹Is a chemical single bond, X²、X³And X⁴When none of them is a substituted amino group, specific examples of the vinyl compound having a functional group containing a silicon atom represented by the above general formula (1) include trialkoxyvinylsilanes such as trimethoxyvinylsilane, triethoxyvinylsilane and tripropoxyvinylsilane, dialkoxyalkylvinylsilanes such as methyldimethoxyvinylsilane and methyldiethoxyvinylsilane, dialkoxyarylvinylsilanes such as di (t-pentyloxy) phenylvinylsilane and di (t-butoxy) phenylvinylsilane, monoalkoxydialkylvinylsilanes such as dimethylmethoxyvinylsilane, monoalkoxydiarylvinylsilanes such as t-butoxydiphenylvinylsilane and t-pentyloxydiphenylvinylsilane, monoalkoxyalkylarylvinylsilanes such as t-butoxymethylphenylvinylsilane and t-butoxyethylphenylsilane, and substituted alkoxyvinylsilane compounds such as tris (β -methoxyethoxy) vinylsilane.

Among the compounds represented by the above general formula (1), X is preferred¹A compound being a single chemical bond, furtherPreferably X¹Is a chemical single bond and X²、X³And X⁴The compound in which 2 of (A) and (B) are substituted amino groups is particularly preferred X¹Is a chemical single bond and X²、X³And X⁴And 2 of them are dialkylamino groups.

Among the compounds represented by the above general formula (1), bis (dimethylamino) methylvinylsilane, bis (diethylamino) methylvinylsilane, and bis (di-n-butylamino) methylvinylsilane are preferable, and bis (diethylamino) methylvinylsilane is particularly preferable.

Examples of the vinyl compound having a functional group capable of interacting with silica other than the compound represented by the above general formula (1) include bis (trialkylsilyl) aminostyrenes such as 4-N, N-bis (trimethylsilyl) aminostyrene and 3-N, N-bis (trimethylsilyl) aminostyrene; bis (trialkylsilyl) aminoalkylstyrenes such as 4-bis (trimethylsilyl) aminomethylstyrene, 3-bis (trimethylsilyl) aminomethylstyrene, 4-bis (trimethylsilyl) aminoethylstyrene, and 3-bis (trimethylsilyl) aminoethylstyrene; pyrrolidinylethylstyrene and the like, and pyrrolidinylethylstyrene is particularly preferable. The pyrrolidinylethylstyrene may be any one of ortho-, meta-and para-positions, preferably meta-and para-positions, and more preferably a mixture of meta-and para-positions.

When the compound represented by the above general formula (1) is used as the vinyl compound having a functional group capable of interacting with silica, the conjugated diene rubber of the present invention is obtained by introducing a unit represented by the following general formula (3) as a unit of the vinyl compound having a functional group capable of interacting with silica.

[ chemical formula 3]

In the above general formula (3), X⁵Represents a single chemical bond or an alkylene group, X⁶、X⁷And X⁸Each independently represents a hydroxyl group, a substituted amino group, a hydrocarbyloxy group, or a hydrocarbon group which may have a substituent.

In the unit represented by the above general formula (3), X⁵Corresponding to X in the compound represented by the above general formula (1)¹In the unit represented by the above general formula (3), X⁶、X⁷And X⁸Respectively corresponding to X in the compound represented by the above general formula (1)²、X³And X⁴. Therefore, in the unit represented by the above general formula (3), X⁵、X⁶、X⁷And X⁸Each of which is capable of reacting with X in the compound represented by the above general formula (1)¹、X²、X³And X⁴The same is true. Further, X is used as the compound represented by the above general formula (1)²、X³And X⁴In the case where at least one of them is a substituted amino group or a hydrocarbyloxy group, X can be hydrolyzed by the substituted amino group or the hydrocarbyloxy group in an arbitrary step and timing to thereby cause X to be present²、X³And X⁴At least one of them becomes a hydroxyl group.

The content ratio of the vinyl compound unit having a functional group capable of interacting with silica in the polymer block (a) is not particularly limited, but is preferably adjusted to a range of preferably 0.01 to 20% by weight, more preferably 0.02 to 2% by weight, and particularly preferably 0.05 to 1% by weight, relative to the total monomer units constituting the conjugated diene rubber. When the content ratio of the vinyl compound unit having a functional group capable of interacting with silica is in the above range, the effect of suppressing adhesion to a roll, and the effects of improving low heat generation and handling stability can be more remarkable.

Further, in the polymer block (a), other monomer units may be contained in addition to the isoprene monomer units, the aromatic vinyl monomer units, and the vinyl compound units containing a functional group capable of interacting with silica. Examples of the other compounds constituting such other monomer units include chain olefin compounds such as ethylene, propylene, and 1-butene; cyclic olefin compounds such as cyclopentene and 2-norbornene; conjugated diene compounds other than isoprene, such as 1, 3-butadiene, 2, 3-dimethyl-1, 3-butadiene, 2-chloro-1, 3-butadiene, 1, 3-pentadiene and 1, 3-hexadiene; non-conjugated diene compounds such as 1, 5-hexadiene, 1, 6-heptadiene, 1, 7-octadiene, dicyclopentadiene and 5-ethylidene-2-norbornene. The content ratio of the other monomer unit in the polymer block (a) is preferably 20% by weight or less, more preferably 10% by weight or less, and further preferably 6% by weight or less.

The weight average molecular weight (Mw) of the polymer block (A) is in the range of 1000 to 30000, preferably in the range of 1500 to 20000, and more preferably in the range of 2000 to 10000. When the weight average molecular weight (Mw) of the polymer block (a) is too small, the effect of suppressing the adhesion to the roller, and the effects of improving the low heat generating property and the handling stability cannot be obtained. On the other hand, when the weight average molecular weight (Mw) of the polymer block (A) is too large, the low heat generating property of the resulting rubber vulcanizate is lowered.

The polymer block (A) preferably has a molecular weight distribution represented by the ratio (Mw/Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of 1.0 to 1.5, more preferably 1.0 to 1.3. When the value (Mw/Mn) of the molecular weight distribution of the polymer block (A) is within the above range, the conjugated diene rubber can be produced more easily. The weight average molecular weight (Mw) and the number average molecular weight (Mn) of the polymer block (a) can be determined as polystyrene equivalent values by gel permeation chromatography.

The polymer block (B) is not particularly limited as long as it contains 1, 3-butadiene monomer units as a main component, and may contain only 1, 3-butadiene monomer units, or may contain 1, 3-butadiene monomer units and monomer units other than 1, 3-butadiene monomer units. In this case, the monomer unit other than the 1, 3-butadiene monomer unit preferably includes an aromatic vinyl monomer unit, and the polymer block (B) of the present invention preferably contains an aromatic vinyl monomer unit in addition to the 1, 3-butadiene monomer unit.

The content ratio of the 1, 3-butadiene monomer unit in the polymer block (B) is preferably 50% by weight or more, more preferably 55 to 95% by weight, and still more preferably 60 to 90% by weight. When the content ratio of the 1, 3-butadiene monomer unit in the polymer block (B) is in the above range, the conjugated diene rubber can be produced more easily.

As the aromatic vinyl compound used for forming the aromatic vinyl monomer unit, the compounds exemplified in the description of the polymer block (a) can be used, and among the above aromatic vinyl compounds, styrene is preferable. The content ratio of the aromatic vinyl monomer unit is preferably 50% by weight or less, more preferably 5 to 45% by weight, and still more preferably 10 to 40% by weight.

In the conjugated diene rubber of the present invention, at least one of the polymer block (a) and the polymer block (B) contains a vinyl compound unit having a functional group capable of interacting with silica, and in the conjugated diene rubber of the present invention, such a vinyl compound unit having a functional group capable of interacting with silica may be contained only in the polymer block (a), only in the polymer block (B), or both in the polymer block (a) and the polymer block (B).

As the vinyl compound having a functional group capable of interacting with silica, which is used for forming the vinyl compound unit having a functional group capable of interacting with silica, the compounds exemplified in the description of the above polymer block (a) can be used, and the preferred compounds exemplified in the description of the above polymer block (a) can be preferably used.

The content ratio of the vinyl compound unit having a functional group capable of interacting with silica in the polymer block (B) is not particularly limited, but is preferably adjusted to a range of preferably 0.01 to 20% by weight, more preferably 0.02 to 2% by weight, and particularly preferably 0.05 to 1% by weight, relative to the total monomer units constituting the conjugated diene rubber.

Further, in the polymer block (B), other monomer units than the 1, 3-butadiene monomer unit, the aromatic vinyl monomer unit and the vinyl compound unit having a functional group capable of interacting with silica may be contained. As the other compound constituting such other monomer unit, isoprene can be used in addition to the same compound as the compound exemplified in the above-mentioned polymer block (a) (except for 1, 3-butadiene). The content ratio of the other monomer unit in the polymer block (B) is preferably 40% by weight or less, more preferably 35% by weight or less, and still more preferably 25% by weight or less.

In addition, as long as the content ratio of the vinyl compound unit having a functional group capable of interacting with silica is within the above range, the content ratio of the 1, 3-butadiene monomer unit in the entire conjugated diene rubber of the present invention is not particularly limited, but is preferably 50 to 99.99% by weight, more preferably 55 to 94.98% by weight, and still more preferably 60 to 89.95% by weight, based on the total monomer units constituting the conjugated diene rubber. In addition, the content ratio of the aromatic vinyl monomer unit in the conjugated diene rubber of the present invention is not particularly limited as long as the content ratio of the vinyl compound unit having a functional group capable of interacting with silica is within the above range, but is preferably 49.99% by weight or less, more preferably 5 to 44.98% by weight, and still more preferably 10 to 39.95% by weight, based on the total monomer units constituting the conjugated diene rubber.

The weight average molecular weight (Mw) of the conjugated diene rubber of the present invention is preferably 50000 to 5000000, more preferably 75000 to 3000000, and still more preferably 100000 to 1000000. By setting the weight average molecular weight of the entire conjugated diene rubber within the above range, silica can be easily blended into a rubber composition containing such a conjugated diene rubber, the processability of the rubber composition can be further improved, and the low heat generation property of the obtained rubber crosslinked product can be further improved.

The total molecular weight distribution of the conjugated diene rubber of the present invention, which is expressed by the ratio (Mw/Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn), is preferably 1.1 to 3.0, more preferably 1.2 to 2.5, and particularly preferably 1.2 to 2.2. When the molecular weight distribution (Mw/Mn) of the entire conjugated diene rubber is in the above range, the low heat build-up property of the resulting rubber crosslinked material can be further improved. The weight average molecular weight (Mw) of the conjugated diene rubber as a whole and the number average molecular weight (Mn) of the rubber as a whole can be determined as values converted to polystyrene by gel permeation chromatography.

The vinyl bond content in the conjugated diene monomer units (for example, isoprene monomer units and 1, 3-butadiene monomer units) in the conjugated diene rubber of the present invention is preferably 1 to 90% by weight, more preferably 3 to 85% by weight, and particularly preferably 5 to 80% by weight. When the vinyl bond content in the conjugated diene monomer units in the entire conjugated diene rubber is in the above range, the resultant rubber crosslinked product can be further excellent in low heat generation properties.

Further, the Mooney viscosity (ML) of the conjugated diene rubber of the present invention₁₊₄Preferably 20 to 100 ℃ at 100 ℃, more preferably 30 to 90 ℃, and particularly preferably 35 to 80 ℃. When the conjugated diene rubber is an oil-extended rubber, the mooney viscosity of the oil-extended rubber is preferably within the above range.

The glass transition temperature (Tg) of the conjugated diene rubber of the present invention is not particularly limited, but is preferably 20 to-110 ℃ and more preferably 10 to-70 ℃. The glass transition temperature of the conjugated diene rubber used in the present invention can be appropriately adjusted by adjusting, for example, the content of the aromatic vinyl monomer unit in the conjugated diene rubber and the content of the vinyl bond in the conjugated diene monomer unit portion.

The conjugated diene rubber of the present invention can be produced, for example, by the following steps: a step of polymerizing a monomer (a) containing isoprene in an inert solvent using a polymerization initiator to form a polymer block (A) having an active end; and

and a step of mixing the obtained polymer block (a) having an active end with a monomer (B) containing 1, 3-butadiene, and continuing the polymerization reaction to obtain a conjugated diene polymer chain having an active end and having the polymer block (a) and the polymer block (B).

As the monomer (a) for forming the polymer block (a), any monomer may be used as long as it contains isoprene, and a monomer corresponding to the monomer composition (the monomer composition) of the formed polymer block (a) may be used. For example, in the case where the polymer block (a) is made to contain an isoprene monomer unit and an aromatic vinyl monomer unit, the monomer (a) may be a monomer containing isoprene and an aromatic vinyl compound. In addition, in the case where the polymer block (a) contains a vinyl compound unit containing a functional group capable of interacting with silica in addition to an isoprene monomer unit and an aromatic vinyl monomer unit, the monomer (a) may contain a vinyl compound containing a functional group capable of interacting with silica in addition to isoprene and an aromatic vinyl compound.

The inert solvent used for the polymerization of the isoprene-containing monomer (a) for forming the polymer block (a) may be an inert solvent generally used in solution polymerization, and is not particularly limited as long as it does not inhibit the polymerization reaction. Specific examples of the inert solvent include linear or branched aliphatic hydrocarbons such as propane, n-butane, isobutane, n-pentane, isopentane, n-hexane, propylene, 1-butene, isobutene, trans-2-butene, cis-2-butene, 1-pentene, 2-pentene, 1-hexene, 2-hexene, and n-heptane; alicyclic hydrocarbons such as cyclopentane and cyclohexane; aromatic hydrocarbons such as benzene, ethylbenzene, toluene, and xylene; ether compounds such as tetrahydrofuran and diethyl ether. These inactive solvents may be used alone in 1 kind, or may be used in combination of 2 or more kinds. The amount of the non-reactive solvent used is not particularly limited, and the monomer concentration is, for example, 1 to 80 wt%, preferably 5 to 50 wt%.

The polymerization initiator for forming the polymer block (a) is not particularly limited as long as it is a polymerization initiator capable of polymerizing the isoprene-containing monomer (a) to form a polymer chain having an active end. Specific examples thereof include a polymerization initiator using an organic alkali metal compound, an organic alkaline earth metal compound, a lanthanide metal compound, or the like as a main catalyst. Examples of the organic alkali metal compound include organic monolithium compounds such as n-butyllithium, sec-butyllithium, tert-butyllithium, hexyllithium, phenyllithium, ethyllithium, n-propyllithium, isopropyllithium, tert-octyllithium, n-decyllithium, 2-naphthyllithium, 2-butylphenyl lithium, 4-phenylbutyllithium, hexyllithium, cyclopentyllithium, a reaction product of diisopropenylbenzene and butyllithium, and distyryllithium; organopolylithium compounds such as dilithiomethane, 1, 4-dilithiobutane, 1, 4-dilithio-2-ethylcyclohexane, 1,3, 5-trilithiobenzene, 1,3, 5-tris (lithiomethyl) benzene, a reaction product of sec-butyllithium and diisopropenylbenzene, a reaction product of n-butyllithium, 1, 3-butadiene and divinylbenzene, and a reaction product of n-butyllithium and a polyacetylene compound; organic sodium compounds such as sodium naphthalene; organic potassium compounds such as potassium naphthalene; an organo rubidium compound; organic cesium compounds, and the like. In addition, alkoxides, sulfonates, carbonates, amides, and the like of lithium, sodium, potassium, and the like can be cited. In addition, other organometallic compounds may also be used in combination. Further, known organic alkali metal compounds disclosed in U.S. Pat. No. 5708092, british patent No. 2241239, U.S. Pat. No. 5527753, and the like can also be used.

Examples of the organic alkaline earth metal compound include di-n-butylmagnesium, di-n-hexylmagnesium, diethoxycarbonitium, calcium distearate, di-t-butoxystrontium, diethoxybutyrate, diisopropoxybutyrate, diethylmercaptobarium, di-t-butoxybarium, diphenoxybarium, diethylaminobarium, barium distearate, and diketobarium. Examples of the polymerization initiator using the lanthanide metal compound as the main catalyst include the following polymerization initiators: the polymerization initiator comprises a salt of a lanthanoid metal as a main catalyst and a cocatalyst such as an alkylaluminum compound, an organoaluminum hydride compound, an organoaluminum halide compound, etc., wherein the salt of the lanthanoid metal is formed from a lanthanoid metal such as lanthanum, cerium, praseodymium, neodymium, samarium, gadolinium, etc., a carboxylic acid, a phosphorus-containing organic acid, etc. Among these polymerization initiators, organic monolithium compounds and organic polylithium compounds are preferably used, organic monolithium compounds are more preferably used, and n-butyllithium is particularly preferably used from the viewpoint of easy industrial availability and easy control of the polymerization reaction. The organic alkali metal compound may be used as an organic alkali metal amide compound by reacting with a secondary amine such as dibutylamine, dihexylamine, dibenzylamine, pyrrolidine, piperidine, hexamethyleneimine or heptamethyleneimine. These polymerization initiators may be used alone in 1 kind, or may be used in combination with 2 or more kinds. The organic alkali metal amide compound is not particularly limited, and examples thereof include lithium hexamethyleneimide, lithium pyrrolidide, lithium piperidide, lithium heptamethyleneimide, lithium dodecamethyleneimide, lithium dimethylamide, lithium diethylamide, lithium dibutylamide, lithium dipropylamide, lithium diheptylamide, lithium dihexylamide, lithium dioctylamide, lithium di-2-ethylhexylamide, lithium didecylamide, lithium N-methylpyrazinade, lithium ethylpropylamide, lithium ethylbutylamide, lithium ethylbenzylamide, and lithium methylphenylethylamide.

The amount of the polymerization initiator to be used may be determined depending on the target molecular weight, and is preferably 4 to 250 mmol, more preferably 6 to 200 mmol, and particularly preferably 10 to 70 mmol, based on 100g of the isoprene-containing monomer (a).

The polymerization temperature in the polymerization of the isoprene-containing monomer (a) is preferably in the range of-80 to +150 ℃, more preferably in the range of 0 to 100 ℃, and still more preferably in the range of 20 to 90 ℃. The polymerization method may be any of a batch method, a continuous method, and the like. In addition, as the bonding mode in the case of forming the polymer block (a) into a copolymer chain, various bonding modes such as a block type, a cone type, and a random type can be used.

In addition, in polymerizing the monomer (a), in order to adjust the vinyl bond content in the isoprene monomer units in the polymer block (a), it is preferable to add a polar compound to an inert solvent during polymerization. Examples of the polar compound include ether compounds such as dibutyl ether, tetrahydrofuran, and 2, 2-bis (tetrahydrofuryl) propane; tertiary amines such as tetramethylethylenediamine; an alkali metal alkoxide; phosphine compounds, and the like. Among them, preferred are ether compounds and tertiary amines, more preferred are tertiary amines, and particularly preferred is tetramethylethylenediamine. These polar compounds may be used alone in 1 kind, or may be used in combination with 2 or more kinds. The amount of the polar compound to be used may be determined in accordance with the intended vinyl bond content, and is preferably 0.01 to 30 moles, and more preferably 0.05 to 10 moles, based on 1 mole of the polymerization initiator. When the amount of the polar compound used is within the above range, the vinyl bond content in the isoprene monomer unit is easily adjusted, and troubles due to deactivation of the polymerization initiator are less likely to occur. Further, by increasing the amount of the polar compound used within the above range, the vinyl bond content in the isoprene monomer unit can be increased.

The vinyl bond content in the isoprene monomer units in the polymer block (A) is preferably 3 to 90 wt%, more preferably 5 to 80 wt%. When the vinyl bond content in the isoprene monomer unit is in the above range, the low heat generation property of the resulting rubber crosslinked product can be further improved. In addition, in the present specification, the vinyl bond content in an isoprene monomer unit means a ratio of a total amount of an isoprene monomer unit having a1, 2-structure and an isoprene monomer unit having a 3, 4-structure in the isoprene monomer unit.

Next, a polymer block (a) having an active end obtained by polymerizing a monomer (a) containing isoprene and a monomer (B) containing 1, 3-butadiene are mixed and the polymerization reaction is continued, whereby a polymer block (B) and a polymer block (a) can be connected to each other, whereby a conjugated diene polymer chain having an active end and containing the polymer block (a) and the polymer block (B) can be obtained. The polymer block (B) formed has a living end, and the living end disappears from the polymer block (A).

As the monomer (B) for forming the polymer block (B), any monomer may be used as long as it contains 1, 3-butadiene, and a monomer corresponding to the monomer composition (the above monomer composition) of the formed polymer block (B) may be used. For example, in the case where the polymer block (B) contains 1, 3-butadiene monomer units and aromatic vinyl monomer units, as the monomer (B), a monomer containing 1, 3-butadiene and an aromatic vinyl compound can be used. In addition, in the case where the polymer block (B) contains a vinyl compound unit containing a functional group capable of interacting with silica in addition to the 1, 3-butadiene monomer unit and the aromatic vinyl monomer unit, the monomer (B) may contain a vinyl compound containing a functional group capable of interacting with silica in addition to 1, 3-butadiene and the aromatic vinyl compound.

In the conjugated diene rubber of the present invention, at least one of the polymer block (a) and the polymer block (B) contains a vinyl compound unit having a functional group capable of interacting with silica. Therefore, in the above-described production method, at least one of the isoprene-containing monomer (a) for forming the polymer block (a) and the 1, 3-butadiene-containing monomer (B) for forming the polymer block (B) may contain a vinyl compound having a functional group capable of interacting with silica.

The inert solvent used for the polymerization of the 1, 3-butadiene-containing monomer (B) for forming the polymer block (B) is not particularly limited, and the same inert solvent as the above-mentioned inert solvent can be used.

The amount of the polymer block (a) having a living end to be used in the formation of the polymer block (B) may be determined depending on the target molecular weight, and is preferably 0.1 to 5mmol, more preferably 0.15 to 2 mmol, and still more preferably 0.2 to 1.5 mmol, based on 100g of the monomer (B) containing 1, 3-butadiene.

The method of mixing the polymer block (a) and the monomer (b) containing 1, 3-butadiene is not particularly limited, and the polymer block (a) having a living end may be added to a solution of the monomer (b) containing 1, 3-butadiene, or the monomer (b) containing 1, 3-butadiene may be added to a solution of the polymer block (a) having a living end. From the viewpoint of controlled polymerization, a method of adding the polymer block (a) having a living end to a solution of the monomer (b) containing 1, 3-butadiene is preferable.

The polymerization temperature in the polymerization of the 1, 3-butadiene-containing monomer (b) is preferably in the range of-80 to +150 ℃, more preferably 0 to 100 ℃, and still more preferably 20 to 90 ℃. The polymerization method may be any of a batch method, a continuous method, and the like. When the polymer block (B) is formed into a copolymer chain, a batch system is preferred in view of easy control of the randomness of the bonding.

The bonding mode in forming the polymer block (B) into a copolymer chain can be various bonding modes such as a block type, a cone type, and a random type. Among them, the random shape is preferable. The random shape further improves the low heat build-up property of the resulting rubber crosslinked material.

In order to adjust the vinyl bond content in the 1, 3-butadiene monomer units in the polymer block (B), it is preferable to add a polar compound to the inert solvent during polymerization in the same manner as when the vinyl bond content in the isoprene monomer units in the polymer block (a) is adjusted. However, when a polar compound is added to the inert solvent in an amount sufficient to adjust the vinyl bond content in the 1, 3-butadiene monomer units of the polymer block (B) in the preparation of the polymer block (A), the polar compound may not be newly added. As the polar compound for adjusting the vinyl bond content, the same compounds as those described above can be used. The amount of the polar compound to be used may be determined in accordance with the target vinyl bond content, and may be adjusted preferably in the range of 0.01 to 100 mol, more preferably 0.1 to 30 mol, based on 1 mol of the polymerization initiator used in the initial polymerization reaction (the polymerization reaction for forming the 1 st polymer block (a)). When the amount of the polar compound used is within this range, the vinyl bond content in the 1, 3-butadiene monomer unit can be easily adjusted, and troubles due to deactivation of the polymerization initiator are less likely to occur.

The vinyl bond content in the 1, 3-butadiene monomer unit in the polymer block (B) is preferably 1 to 90% by weight, more preferably 3 to 85% by weight, and particularly preferably 5 to 80% by weight. When the vinyl bond content in the 1, 3-butadiene monomer unit in the polymer block (B) is in the above range, the resulting rubber vulcanizate can have more excellent low heat build up.

In this manner, a conjugated diene polymer chain having an active end and having a polymer block (a) and a polymer block (B) can be obtained. In the present invention, from the viewpoint of productivity, the conjugated diene polymer chain having an active end is preferably configured so that the polymer block (a) is the polymer block (B) and the end of the polymer block (B) is the active end, but a plurality of polymer blocks (a) may be provided and another polymer block may be provided. Examples thereof include a conjugated diene polymer chain having an active end such as the polymer block (A) -the polymer block (B) -the polymer block (A). In this case, an active end is formed at the end of the polymer block (a) formed by connecting the polymer blocks (B). When the polymer block (a) is formed on the active terminal side of the conjugated diene polymer chain, the amount of isoprene used is preferably 10 to 100 moles, more preferably 15 to 70 moles, and particularly preferably 20 to 35 moles, based on 1 mole of the polymerization initiator used in the initial polymerization reaction (the polymerization reaction for forming the 1 st polymer block (a)).

Then, the conjugated diene polymer chain having an active end and having the polymer block (a) and the polymer block (B) obtained in this manner can be inactivated at the active end by adding a conventionally used coupling agent, or a polymerization terminator such as an alcohol such as methanol, ethanol, or isopropanol, or water, or the like to the polymerization system, thereby obtaining a solution of the conjugated diene rubber.

In the solution of the conjugated diene rubber obtained as described above, if desired, an antioxidant such as a phenol stabilizer, a phosphorus stabilizer, a sulfur stabilizer, or the like, a aggregating agent, a scale inhibitor, or the like is added to the reaction solution, and then the polymerization solvent is separated from the reaction solution by direct drying, a steam stripping method, or the like, to recover the solid conjugated diene rubber. Further, the conjugated diene rubber may be compounded with an operating Oil (Extender Oil) as desired to prepare an Oil-extended rubber (Oil-filledrubber). Examples of the process oil include petroleum softeners, vegetable softeners, and fatty acids of paraffin, aromatic, and naphthene series. In the case of using a PETROLEUM-based softener, the content of polycyclic aromatic compounds extracted by the method of IP346 (detection method of theinstitate PETROLEUM in the uk) is preferably less than 3%. When the process oil is used, the amount of the process oil used is usually 5 to 100 parts by weight per 100 parts by weight of the conjugated diene rubber.

The weight ratio of the polymer block (a) to the polymer block (B) (in the case where a plurality of polymer blocks (a) and (B) are present, the weight ratio based on the total weight of each of the polymer blocks) in the conjugated diene rubber of the present invention is preferably 0.001 to 0.2, more preferably 0.005 to 0.1, and particularly preferably 0.01 to 0.05 in terms of (the weight of the polymer block (a)/(the weight of the polymer block (B)). When the weight ratio of the polymer block (A) to the polymer block (B) is in the above range, the resulting rubber crosslinked material can have a good balance between wet grip properties and low heat build-up properties.

In addition, from the viewpoint of further improving the affinity for silica, the polymer chain end of the conjugated diene rubber of the present invention may be modified with a functional group containing a hetero atom. The heteroatom-containing functional group is not particularly limited as long as it is a heteroatom-containing group, and the heteroatom preferably contains at least 1 group selected from a nitrogen atom, an oxygen atom and a silicon atom, more preferably contains a nitrogen atom or a silicon atom, and particularly preferably contains a silicon atom from the viewpoint of affinity for silica.

The functional group containing a hetero atom can be introduced into the polymer chain end of the conjugated diene rubber by, for example, reacting a compound containing a hetero atom with the active end of the conjugated diene polymer chain having active ends of the polymer block (a) and the polymer block (B) obtained by the above-described production method.

As the silicon atom-containing compound used in the case where the silicon atom-containing functional group is a heteroatom-containing functional group, for example, a siloxane compound can be preferably used. The siloxane compound is not particularly limited as long as it has a siloxane structure (-Si — O-) as a main chain, but is preferably an organosiloxane having an organic group in a side chain, and more preferably a polyorganosiloxane represented by the following general formula (4).

[ chemical formula 4]

In the above general formula (4), R³～R¹⁰The alkyl group having 1 to 6 carbon atoms or the aryl group having 6 to 12 carbon atoms may be the same or different from each other. X⁹And X¹²The epoxy resin composition is any one selected from the group consisting of an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, and a group having 4 to 12 carbon atoms and containing an epoxy group, and these may be the same or different from each other. X¹⁰Is an alkoxy group having 1 to 5 carbon atoms or a group having 4 to 12 carbon atoms containing an epoxy group, when X is¹⁰When a plurality of them are used, they may be the same as or different from each other. X¹¹A group containing 2 to 20 repeating units of alkylene glycol when X¹¹When a plurality of them are used, they may be the same as or different from each other. m is an integer of 1 to 200, n is an integer of 0 to 200, k is an integer of 0 to 200, and m + n + k is 1 or more.

In the polyorganosiloxane represented by the general formula (4), R as R constituting the general formula (4)³～R¹⁰、X⁹And X¹²Examples of the alkyl group having 1 to 6 carbon atoms include methyl, ethyl, n-propyl, isopropyl, butyl, pentyl, hexyl, and cyclohexyl groups. Examples of the aryl group having 6 to 12 carbon atoms include a phenyl group, a methylphenyl group and the like. Among them, methyl and ethyl groups are preferable from the viewpoint of easy production of the polyorganosiloxane itself.

In addition, in the polyorganosiloxane represented by the above general formula (4), X is a constitutional X⁹、X¹⁰And X¹²Examples of the alkoxy group having 1 to 5 carbon atoms include methoxy, ethoxy, propoxy, isopropoxy and butoxy. Among them, leisurelyMethoxy and ethoxy groups are preferred from the viewpoint of ease of production of the polyorganosiloxane itself.

Further, in the polyorganosiloxane represented by the above general formula (4), X is a constitutional X⁹、X¹⁰And X¹²Examples of the group having 4 to 12 carbon atoms and containing an epoxy group in (2) include a group represented by the following general formula (5).

-Z¹-Z²-E(5)

In the above general formula (5), Z¹Is alkylene or alkylarylene having 1 to 10 carbon atoms, Z²Is methylene, sulfur or oxygen, E is a hydrocarbon group having 2 to 10 carbon atoms and an epoxy group.

As the group represented by the above general formula (5), Z is preferred²Is an oxygen atom, more preferably Z²Is an oxygen atom and E is a glycidyl group, with Z being particularly preferred¹Is alkylene having 1 to 3 carbon atoms, Z²Is an oxygen atom and E is a glycidyl group.

In addition, in the polyorganosiloxane represented by the above general formula (4), in the above formula, X is⁹And X¹²Preferably, the epoxy group-containing group has 4 to 12 carbon atoms or an alkyl group having 1 to 6 carbon atoms. In the above formula, X is¹⁰Preferably, the epoxy group-containing group has 4 to 12 carbon atoms. Further, X is more preferable⁹And X¹²Is alkyl with 1-6 carbon atoms, X¹⁰The epoxy group-containing group has 4 to 12 carbon atoms.

In addition, in the polyorganosiloxane represented by the above general formula (4), X is¹¹That is, the group containing 2 to 20 repeating units of an alkylene glycol is preferably a group represented by the following general formula (6).

[ chemical formula 5]

In the general formula (6), t is an integer of 2 to 20, X¹³Is alkylene or alkylarylene with 2-10 carbon atoms, R¹¹Is a hydrogen atom or a methyl group, X¹⁴Is an alkoxy group or aryloxy group having 1 to 10 carbon atoms. Among them, preferred are: t is an integer of 2 to 8, X¹³Is alkylene with 3 carbon atoms, R¹¹Is a hydrogen atom and X¹⁴Is methoxy.

In the polyorganosiloxane represented by the above general formula (4), m is an integer of 1 to 200, preferably an integer of 20 to 150, and more preferably an integer of 30 to 120. When m is 1 to 200, the polyorganosiloxane itself represented by the general formula (4) can be produced more easily, and the handling is easier without excessively increasing the viscosity.

In the polyorganosiloxane represented by the above general formula (4), n is an integer of 0 to 200, preferably an integer of 0 to 150, and more preferably an integer of 0 to 120. k is an integer of 0 to 200, preferably an integer of 0 to 150, and more preferably an integer of 0 to 130. The total number of m, n and k is 1 or more, preferably 3 to 400, more preferably 20 to 300, and particularly preferably 30 to 250. When the total number of m, n and k is 1 or more, the reaction between the polyorganosiloxane represented by the above general formula (4) and the conjugated diene polymer chain having an active terminal is easily progressed, and further, when the total number of m, n and k is 400 or less, the polyorganosiloxane itself represented by the above general formula (4) is easily produced, and the viscosity thereof is not excessively high, and the handling is easy.

Further, as the compound containing a silicon atom, a compound represented by the following general formula (7) or a vinyl compound containing a silicon-containing functional group represented by the above general formula (1) can also be preferably used.

[ chemical formula 6]

In the above general formula (7), X¹⁵～X¹⁷Each independently is-R¹³A group represented by-OR¹⁴A group of (R)¹³、R¹⁴Is an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, preferably an alkyl group having 1 to 6 carbon atoms, more preferably a methyl group or an ethyl group, and particularly preferably a methyl group。)，X¹⁵～X¹⁷At least one of which is-OR¹⁴A group represented by, preferably X¹⁵～X¹⁷Wherein all are-OR¹⁴The group shown. Furthermore, R¹²Is an alkylene group having 1 to 6 carbon atoms, preferably an alkylene group having 2 to 5 carbon atoms, and particularly preferably a trimethylene group. X¹⁸、X¹⁹Each independently is-R¹⁵A group represented by-SiR¹⁶R¹⁷R¹⁸A group of (R)¹⁵、R¹⁶、R¹⁷、R¹⁸The alkyl group having 1 to 6 carbon atoms or the aryl group having 6 to 12 carbon atoms may contain a silicon atom, a nitrogen atom or an oxygen atom, preferably an alkyl group having 1 to 6 carbon atoms, more preferably a methyl group or an ethyl group, and particularly preferably an ethyl group. ) X is¹⁸、X¹⁹Preferably both are represented by-R¹⁵The group shown. In addition, X may be replaced by¹⁷And X¹⁹The silicon atom and the nitrogen atom in the general formula (7) are directly covalently bonded.

In addition, as the compound containing a hetero atom other than the compound containing a silicon atom, a compound containing a nitrogen atom can be cited, and as such a compound, a compound represented by the following general formula (8) can be preferably used.

[ chemical formula 7]

In the above general formula (8), R¹⁹～R²²Each independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, preferably a hydrogen atom. R²³Is an alkylene group having 1 to 6 carbon atoms, preferably an alkylene group having 2 to 5 carbon atoms, and particularly preferably a trimethylene group. R²⁴、R²⁵Each independently a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, preferably an alkyl group having 1 to 6 carbon atoms, more preferably a methyl group or an ethyl group, and particularly preferably a methyl group.

Examples of the compound containing a nitrogen atom other than the compound represented by the above general formula (8) include urea compounds such as N, N ' -dimethylurea, N ' -diethylurea, N ' -tetramethylurea, and N, N-dimethyl-N ', N ' -diphenylurea; imide compounds such as succinimide, N-methylsuccinimide, maleimide, N-methylmaleimide, phthalimide and N-methylphthalimide; 1, 3-diethyl-2-imidazolidinone, 1, 3-dimethyl-2-imidazolidinone, 1-dipropyl-2-imidazolidinone, 1-methyl-3-ethyl-2-imidazolidinone, 1-methyl-3-propyl-2-imidazolidinone, alkyl-substituted imidazolidinone compounds such as 1-methyl-3-butyl-2-imidazolidinone, 1-methyl-3- (2-methoxyethyl) -2-imidazolidinone, 1-methyl-3- (2-ethoxyethyl) -2-imidazolidinone, and 1, 3-bis- (2-ethoxyethyl) -2-imidazolidinone; pyridyl-substituted ketone compounds and/or pyridyl-substituted vinyl compounds such as methyl-2-pyridone, methyl-4-pyridone, propyl-2-pyridone, di-4-pyridone, propyl-3-pyridone, 2-benzoylpyridine, 2-vinylpyridine, and 4-vinylpyridine; lactam compounds such as 2-pyrrolidone, N-methylpyrrolidone, N-phenylpyrrolidone, 2-piperidone, 2-quinolone, N-methylquinolone and ketocaprolactam. Among them, lactam compounds are preferred, and N-phenylpyrrolidone is more preferred from the viewpoint of further improving the low heat build-up property of the resulting rubber crosslinked product.

The method of reacting the heteroatom-containing compound with the conjugated diene polymer chain having an active terminal obtained by the above-mentioned production method and having the polymer block (a) and the polymer block (B) (hereinafter, appropriately referred to as "conjugated diene polymer chain having an active terminal") is not particularly limited, and a method of mixing them in a solvent in which each of them can be dissolved may be mentioned. As the solvent used in this case, solvents exemplified as the inactive solvent used in the polymerization of the conjugated diene polymer chain having an active terminal having the polymer block (a) and the polymer block (B) can be used. In this case, a method of adding a heteroatom-containing compound to a polymerization solution used for polymerization to obtain a conjugated diene polymer chain having an active end and having a polymer block (a) and a polymer block (B) is preferred because of its simplicity. In this case, the compound containing a hetero atom may be dissolved in an inert solvent and added to the polymerization system. The reaction temperature is not particularly limited, but is usually 0 to 120 ℃ and the reaction time is not particularly limited, but is usually 1 minute to 1 hour.

When the conjugated diene polymer chain having an active end is reacted with the heteroatom-containing compound, the amount of the heteroatom-containing compound to be used is preferably 0.01 to 10 moles, and more preferably 0.1 to 5 moles, based on 1 mole of the polymerization initiator used in the initial polymerization reaction (the polymerization reaction for forming the 1 st polymer block (a)). When the amount of the hetero atom-containing compound used is within the above range, the low heat generating property of the resulting rubber vulcanizate can be further improved. When a siloxane compound such as polyorganosiloxane represented by the above general formula (4) is used as the heteroatom-containing compound, the number of moles per siloxane structure (-Si-O-) is preferably in the above range.

The timing of adding the heteroatom-containing compound to the solution containing the conjugated diene polymer chain having an active terminal is not particularly limited, but it is desirable to add the heteroatom-containing compound to the solution in a state where the polymerization reaction is not completed and the solution containing the conjugated diene polymer chain having an active terminal further contains a monomer, more specifically, in a state where the solution containing the conjugated diene polymer chain having an active terminal contains 100ppm or more, more preferably 300 to 50000ppm of a monomer. By adding the heteroatom-containing compound in this manner, side reactions of the conjugated diene polymer chain having an active end and impurities and the like contained in the polymerization system can be suppressed, and the reaction can be controlled well. In the case of using 2 or more compounds as the heteroatom-containing compound, the timing of adding these compounds and reacting them is not particularly limited, and these compounds may be added simultaneously and reacted simultaneously, or in the case of using 2 compounds as the heteroatom-containing compound, only 1 species may be added in advance and reacted, and then the remaining 1 species may be added and reacted. In addition, in the case of using 3 or more compounds as the heteroatom-containing compound, the timing of addition can be 2 stages or 3 stages or more. In order to further improve the processability of the obtained rubber composition, a compound containing a hetero atom may be added to a solution containing a conjugated diene polymer chain having an active terminal, and after reaction, an organic metal compound may be further mixed, whereby the processability of the obtained rubber composition can be improved (the complex mooney viscosity can be suppressed to be low). In this case, after the organometallic compound is mixed, a heteroatom-containing compound may be further added to the mixture to further react the mixture. Examples of the organometallic compound include n-butyllithium, sec-butyllithium, tert-butyllithium, hexyllithium, phenyllithium, ethyllithium, n-propyllithium, isopropyllithium, tert-octyllithium, n-decyllithium, 2-naphthyllithium, 2-butylphenyl lithium, 4-phenylbutyllithium, hexyllithium, cyclopentyllithium, a reaction product of diisopropenylbenzene and butyllithium, and an organic monolithium compound such as diphenylethyllithium.

In this manner, the heteroatom-containing compound is reacted with the active end of the conjugated diene polymer chain having an active end, whereby the heteroatom-containing functional group can be bonded to at least a part of the ends of the conjugated diene polymer chain. In the conjugated diene polymer chain after the reaction, a functional group containing a hetero atom is introduced into a terminal of the polymer chain, but in addition to this, an unmodified conjugated diene polymer chain which is not modified with a functional group containing a hetero atom may be contained in the conjugated diene polymer chain.

Further, as the conjugated diene polymer chain having an active end, a polymer chain in which the end of the polymer block (a) is an active end (for example, a polymer chain represented by the polymer block (a) -the polymer block (B) -the polymer block (a)) may be used, and a heteroatom-containing functional group may be introduced into the end of the polymer block (a) by reacting a heteroatom-containing compound with the end of the polymer block (a), or a polymer chain in which the end of the polymer block (B) is an active end (for example, a polymer chain represented by the polymer block (a) -the polymer block (B)) may be used, and a heteroatom-containing functional group may be introduced into the end of the polymer block (B) by reacting a heteroatom-containing compound with the end of the polymer block (B). From the viewpoint of further improving the low heat generating property of the resulting rubber crosslinked product, it is preferable to introduce a functional group containing a hetero atom into the terminal of the polymer block (B) by reacting a compound containing a hetero atom with the terminal of the polymer block (B).

In addition, in the case where the compound containing a hetero atom is in a state before the compound containing a hetero atom is reacted with the conjugated diene polymer chain having an active terminal, or in the case where the conjugated diene polymer chain having an active terminal remains after the compound containing a hetero atom is reacted with the conjugated diene polymer chain having an active terminal, a coupling agent or the like which has been conventionally and generally used may be added to the polymerization system to couple a part of the active terminal of the conjugated diene polymer chain having an active terminal, within a range in which the effect of the present invention is not impaired.

Further, it is preferable that after the compound containing a hetero atom is reacted with the conjugated diene polymer chain having an active end, a polymerization terminator such as alcohol such as methanol, ethanol, or isopropanol, or water is added to inactivate the unreacted active end.

After the active terminal of the conjugated diene polymer chain is deactivated, an antioxidant such as a phenol stabilizer, a phosphorus stabilizer or a sulfur stabilizer, a aggregating agent, a scale inhibitor or the like is added to the reaction solution as desired in a solution of the conjugated diene rubber having a functional group containing a hetero atom at the terminal, and then the polymerization solvent is separated from the reaction solution by direct drying or a steam stripping method or the like, thereby recovering the solid conjugated diene rubber having a functional group containing a hetero atom at the terminal. Before the separation of the polymerization solvent from the reaction solution, the process oil may be mixed with the polymerization solution to recover the conjugated diene rubber as an oil-extended rubber. The process oil used in the above amount can be used.

< rubber composition >

The rubber composition of the present invention is a composition obtained by adding silica to a rubber component containing the conjugated diene rubber of the present invention.

The rubber composition of the present invention may contain other rubbers in addition to the conjugated diene rubber of the present invention. The other rubber means, for example, a natural rubber (may be a modified natural rubber such as an Epoxidized Natural Rubber (ENR), a Hydrogenated Natural Rubber (HNR), a deproteinized natural rubber (DPNR), a high-purity natural rubber (uprr), a grafted natural rubber, etc.), a polyisoprene rubber, an emulsion-polymerized styrene-butadiene copolymer rubber, a solution-polymerized styrene-butadiene copolymer rubber, a polybutadiene rubber (may be a high cis-BR or a low cis BR., or a polybutadiene rubber containing a crystalline fiber containing a1, 2-polybutadiene polymer), a styrene-isoprene copolymer rubber, a butadiene-isoprene copolymer rubber, a styrene-isoprene-butadiene copolymer rubber, an acrylonitrile-styrene-butadiene copolymer rubber, a styrene-isoprene-butadiene copolymer rubber, a styrene-butadiene copolymer rubber, Rubbers other than the above-mentioned conjugated diene rubbers, such as butyl rubber (IIR), ethylene-propylene copolymer, chloroprene rubber, nitrile chloroprene rubber, and nitrile isoprene rubber. Among them, natural rubber, polyisoprene rubber, polybutadiene rubber and solution-polymerized styrene-butadiene copolymer rubber are preferable. These rubbers can be used singly or in combination of 2 or more kinds, respectively, such as natural rubber and polybutadiene rubber, natural rubber and styrene-butadiene copolymer rubber, and the like.

In the rubber composition of the present invention, the conjugated diene rubber of the present invention is preferably 10 to 100% by weight, particularly preferably 50 to 100% by weight, of the rubber component in the rubber composition. By including the conjugated diene rubber of the present invention in the rubber component in such a ratio, a rubber crosslinked product excellent in low heat generation property and handling stability can be obtained.

Examples of the silica used in the present invention include dry process silica, wet process silica, colloidal silica, precipitated silica, calcium silicate, and aluminum silicate. Among them, wet process white carbon containing hydrous silicic acid as a main component is preferable. In addition, a carbon-silica dual-phase filler in which silica is supported on the surface of carbon black may also be used. These silicas can be used individually, or 2The above components can be used in combination. The nitrogen adsorption specific surface area (measured by BET method based on ASTM D3037-81) of the silicon dioxide used is preferably 20-400 m²(iv)/g, more preferably 50 to 220m²A specific preferred range is 80 to 170m²(ii) in terms of/g. The pH of the silica is preferably 5 to 10.

The silica used in the present invention preferably has a dibutyl phthalate (DBP) absorption value in the range of about 100 to about 400, and particularly preferably in the range of about 150 to about 300.

The silica used in the present invention preferably has an average limit particle diameter in the range of 0.01 to 0.05 μm as measured by an electron microscope, but the average limit particle diameter of the silica is not limited to this range, and may be smaller or larger.

As the silica used in the present invention, various commercially available silicas can be used, for example. Examples thereof include: Hi-Sil, 210, Hi-Sil233, Hi-Sil243LD manufactured by PPG Industries, Inc.; zeosil1115MP, Zeosil1165MP, and Zeosil165GR manufactured by Rhodia; ULTRASIL VN2 and ULTRASIL VN3 manufactured by EVONIK Inc.

The amount of silica incorporated in the rubber composition of the present invention is preferably 10 to 250 parts by weight, more preferably 15 to 150 parts by weight, and still more preferably 20 to 130 parts by weight, based on 100 parts by weight of the rubber component in the rubber composition. When the amount of silica is within the above range, the low heat build-up property and the handling stability of the resulting rubber crosslinked product can be further improved.

From the viewpoint of further improving the low heat generation property, a silane coupling agent may be further blended in the rubber composition of the present invention. The silane coupling agent is not particularly limited, and various silane coupling agents can be used, and in the present invention, sulfide-based, mercapto-based, protected mercapto-based (for example, coupling agent having carbonylthio), thiocyanate-based, vinyl-based, amino-based, methacrylate-based, glycidoxy-based, nitro-based, epoxy-based, or chlorine-based silane coupling agents can be preferably used. Specific examples of the silane coupling agent include: bis (3- (triethoxysilyl) propyl) disulfide, bis (3-triethoxysilylpropyl) trisulfide, bis (3- (triethoxysilyl) propyl) tetrasulfide, γ -mercaptopropyltriethoxysilane, 3- [ ethoxybis (3,6,9,12, 15-pentaoxaoctacosan-1-yloxy) silyl ] -1-propanethiol, 3-octanoylthio-1-propyl-triethoxysilane, 3-trimethoxysilylpropyl-N, N-dimethylthiocarbamoyl tetrasulfide, γ -trimethoxysilylpropyl benzothiazolyl tetrasulfide, 3-trimethoxysilylpropyl benzothiazole tetrasulfide, 3-thiocyanate propyltriethoxysilane, a mixture of these, and a pharmaceutically acceptable salt thereof, Vinyltriethoxysilane, N- (beta-aminoethyl) -gamma-aminopropyltrimethoxysilane, 3-trimethoxysilylpropyl methacrylate monosulfide, gamma-glycidoxypropyltriethoxysilane, 3-nitropropyltrimethoxysilane, beta- (3, 4-epoxycyclohexyl) ethyltrimethoxysilane, and 3-chloropropyltrimethoxysilane. Further, NXT-Z100, NXT-Z30, NXT-Z45, NXT-Z60, NXT-Z45, NXT, Si69, Si75, VP Si363, etc. manufactured by Evonik Degussa can also be used. These silane coupling agents can be used individually or in combination of 2 or more. Further, 1 or 2 or more of them may be previously oligomerized and used in an oligomerized state. The amount of the silane coupling agent is preferably 0.1 to 30 parts by weight, more preferably 1 to 15 parts by weight, based on 100 parts by weight of silica.

Further, carbon black such as furnace black, acetylene black, thermal black, channel black and graphite may be further blended in the rubber composition of the present invention. Among them, furnace carbon black is preferred. These carbon blacks may be used individually or in combination of 2 or more. The amount of carbon black is usually not more than 120 parts by weight per 100 parts by weight of the rubber component in the rubber composition.

The method of adding silica to the rubber component containing the conjugated diene rubber of the present invention is not particularly limited, and a method of adding and kneading a solid rubber component (dry kneading method); a method (wet kneading method) of adding a solution containing a conjugated diene rubber to the solution, coagulating the solution, and drying the coagulated solution.

The rubber composition of the present invention preferably further contains a crosslinking agent. Examples of the crosslinking agent include sulfur-containing compounds such as sulfur and halogenated sulfur, organic peroxides, quinone dioxides, organic polyamine compounds, and alkylphenol resins having a methylol group. Among them, sulfur is preferably used. The amount of the crosslinking agent is preferably 0.1 to 15 parts by weight, more preferably 0.5 to 5 parts by weight, and particularly preferably 1 to 4 parts by weight, based on 100 parts by weight of the rubber component in the rubber composition.

In addition to the above components, the rubber composition of the present invention may further contain compounding agents such as a crosslinking accelerator, a crosslinking activator, an antioxidant, a filler (other than the above silica and carbon black), an activator, a processing oil, a plasticizer, a lubricant, and a tackifier in required amounts by a conventional method.

In the case where sulfur or a sulfur-containing compound is used as the crosslinking agent, it is preferable to use a crosslinking accelerator and a crosslinking activator in combination. Examples of the crosslinking accelerator include sulfenamide crosslinking accelerators; a guanidine-based crosslinking accelerator; a thiourea-based crosslinking accelerator; a thiazole-based crosslinking accelerator; a thiuram-based crosslinking accelerator; a dithiocarbamate-based crosslinking accelerator; and xanthic acid crosslinking accelerators. Among them, a sulfenamide-based crosslinking accelerator is preferably contained. These crosslinking accelerators may be used individually or in combination of 2 or more. The amount of the crosslinking accelerator is preferably 0.1 to 15 parts by weight, more preferably 0.5 to 5 parts by weight, and particularly preferably 1 to 4 parts by weight, based on 100 parts by weight of the rubber component in the rubber composition.

Examples of the crosslinking activator include higher fatty acids such as stearic acid; zinc oxide, and the like. These crosslinking activators may be used individually or in combination of 2 or more. The amount of the crosslinking activator is preferably 0.05 to 20 parts by weight, and particularly preferably 0.5 to 15 parts by weight, based on 100 parts by weight of the rubber component in the rubber composition.

In order to obtain the rubber composition of the present invention, the respective components may be kneaded according to a conventional method, and for example, components other than thermally unstable components such as a crosslinking agent and a crosslinking accelerator may be kneaded with the conjugated diene rubber, and then the thermally unstable components such as a crosslinking agent and a crosslinking accelerator may be mixed with the kneaded product to obtain a target composition. The temperature for kneading the components other than the thermally unstable component and the conjugated diene rubber is preferably 80 to 200 ℃, more preferably 120 to 180 ℃, and the kneading time is preferably 30 seconds to 30 minutes. The mixing of the kneaded product with the thermally unstable component is usually carried out after cooling to 100 ℃ or lower, and preferably after cooling to 80 ℃ or lower.

< crosslinked rubber >

The rubber crosslinked material of the present invention is obtained by crosslinking the rubber composition of the present invention.

The crosslinked rubber product of the present invention can be produced by the following method: the rubber composition of the present invention is molded into a desired shape by a molding machine such as an extruder, an injection molding machine, a compressor, a roll, etc., and the shape is fixed by a crosslinking reaction by heating to obtain a crosslinked rubber product. In this case, crosslinking may be performed after molding in advance, or may be performed simultaneously with molding. The molding temperature is usually 10 to 200 ℃, preferably 25 to 120 ℃. The crosslinking temperature is usually 100 to 200 ℃, preferably 130 to 190 ℃, and the crosslinking time is usually 1 minute to 24 hours, preferably 2 minutes to 12 hours, and particularly preferably 3 minutes to 6 hours.

Further, depending on the shape and size of the rubber crosslinked material, the interior may not be sufficiently crosslinked even when the surface is crosslinked, and therefore, the rubber may be further heated to perform secondary crosslinking.

As the heating method, a general method for crosslinking the rubber, such as press heating, steam heating, oven heating, and hot air heating, can be appropriately selected.

The rubber crosslinked material of the present invention obtained in this manner is obtained by using the conjugated diene rubber of the present invention described above, and therefore is excellent in low heat build-up property and handling stability. In particular, the conjugated diene rubber of the present invention has a polymer block (a) containing isoprene monomer units as a main component and having a weight average molecular weight (Mw) within a specific range and a polymer block (B) containing 1, 3-butadiene monomer units as a main component, and at least one of the polymer blocks contains a vinyl compound unit containing a functional group capable of interacting with silica, and therefore, due to the action of the polymer block (a) and the vinyl compound unit containing a functional group capable of interacting with silica, the affinity for a filler such as silica is high, and thus the filler such as silica can be well dispersed, and the reinforcing property of the filler such as silica can be sufficiently exhibited. Therefore, the rubber crosslinked material of the present invention obtained using the conjugated diene rubber of the present invention has excellent low heat build-up property and handling stability.

The rubber vulcanizate of the present invention effectively utilizes its excellent low heat build-up and handling stability, and can be used for materials for various parts of tires such as treads, tread bases, carcasses, sidewalls, bead portions, etc. in tires; materials for hoses, belts, mats, vibration-proof rubbers, other various industrial products; impact resistance improvers for resins; a resin film buffer; a sole; rubber shoes; a golf ball; toys, and the like. In particular, the rubber crosslinked material of the present invention is excellent in low heat build-up property and handling stability, and therefore can be preferably used as a material for a low fuel consumption tire, and is most suitable for use in a tread.