JP5194846B2 - Rubber composition for base tread - Google Patents

Description

  The present invention relates to a rubber composition for a base tread that is used for constituting a base tread of a tire, and more specifically, for a base tread that is suitably used as a base tread of a fuel-efficient tire and that is particularly excellent in low heat generation. The present invention relates to a rubber composition.

  In recent years, with the emphasis on resource saving and environmental measures, the level of demand for automobile tires with excellent fuel efficiency has been increasing. As a method of manufacturing tires with excellent fuel efficiency, the tread is composed of two layers, a cap tread on the ground contact side and a base tread on the opposite side. It is known to use a rubber material that can form a crosslinked rubber that is excellent in resistance to heat generation during running.

  In recent years, in view of the increasing demand for low fuel consumption for tires, a technique for improving the low heat buildup of the rubber material constituting the base tread has been studied in order to obtain a tire with better fuel efficiency. Yes. For example, Patent Documents 1 to 3 disclose a technique for obtaining a rubber composition for a base tread (under tread) excellent in low heat buildup by blending specific carbon black or silica. In Patent Document 4, a rubber composition composed of a polybutadiene rubber containing a specific amount of a 1,2-syndiotactic structure and a tin-modified polybutadiene rubber is excellent in low heat build-up (rolling resistance), It is described that it is suitably used as a rubber composition for a base tread. However, even when these rubber compositions are used, the low exothermic property may still be insufficient, and further improvement has been desired.

JP 2003-12866 A JP 2005-248020 A JP 2005-68196 A JP 2006-124503 A

  An object of the present invention is to provide a rubber composition for a base tread that is particularly excellent in low heat build-up and a tire obtained by using the rubber composition.

  As a result of diligent research to achieve the above object, the present inventors have made a specific glass transition temperature by reacting a modifying agent having a specific structure with the active end of a conjugated diene polymer chain having an active end. It was found that a rubber composition obtained using this modified conjugated diene rubber and silica has excellent low heat build-up. The present invention has been completed based on this finding.

（一般式（Ｉ）において、Ｒ ^１ 〜Ｒ ^８ は、炭素数１〜６のアルキル基または炭素数６〜１２のアリール基であり、これらは互いに同一であっても相違してもよい。Ｘ ^１ およびＸ ^４ は、炭素数１〜５のアルコキシル基、炭素数６〜１４のアリールオキシ基、エポキシ基を含有する炭素数４〜１２の基、炭素数１〜６のアルキル基、または炭素数６〜１２のアリール基であり、Ｘ ^１ およびＸ ^４ は同一であっても相違してもよい。Ｘ ^２ は、炭素数１〜５のアルコキシル基、炭素数６〜１４のアリールオキシ基またはエポキシ基を含有する炭素数４〜１２の基である。Ｘ ^３ は、２〜２０のアルキレングリコールの繰返し単位を含有する基である。ｍは２〜２００の整数、ｎは０〜２００の整数、ｋは０〜２００の整数である。）
または、下記一般式（ＩＶ）：

（一般式（ＩＶ）において、Ｒ ^２０ は、炭素数１〜１２のアルキレン基である。Ｒ ^２１ 〜Ｒ ^２５ は、炭素数１〜６のアルキル基または炭素数６〜１２のアリール基であり、これらは互いに同一であっても相違してもよい。ｑは１または２、ｒは１〜１０の整数である。）
で表される化合物であり、
上記変性共役ジエンゴムが、共役ジエン単量体単位部分におけるビニル結合含有量が１〜４０モル％であり、芳香族ビニル単量体単位１５〜０重量％を含んでなる共役ジエン重合体鎖で構成され、ガラス転移温度−１１０〜−４０℃を有する変性共役ジエンゴムである
ことを特徴とするベーストレッド用ゴム組成物が提供される。
Thus, according to the present invention, the active end of the conjugated diene polymer chain having the active end, and a rubber component 100 parts by weight containing modified conjugated diene rubber ing by reacting a denaturation agent, silica 10-60 parts by weight A rubber composition for a base tread comprising :
The modifying agent is represented by the following general formula (I):

(In General Formula (I), R ^{1 to} R ⁸ are each an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, which may be the same or different from each other. X ¹ and X ⁴ are each an alkoxyl group having 1 to 5 carbon atoms, an aryloxy group having 6 to 14 carbon atoms, a group having 4 to 12 carbon atoms containing an epoxy group, an alkyl group having 1 to 6 carbon atoms, or a carbon number X ¹ and X ⁴ may be the same or different, and X ² is an alkoxyl group having 1 to 5 carbon atoms, an aryloxy group having 6 to 14 carbon atoms, or an epoxy. A group containing a group having 4 to 12 carbon atoms, X ³ is a group containing a repeating unit of 2 to 20 alkylene glycol, m is an integer of 2 to 200, n is an integer of 0 to 200, k is an integer of 0 to 200.)
Or the following general formula (IV):

(In General Formula (IV), R ²⁰ is an alkylene group having 1 to 12 carbon atoms. R ^{21 to} R ²⁵ are an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, These may be the same or different from each other, q is 1 or 2, and r is an integer of 1 to 10.)
A compound represented by
The modified conjugated diene rubber comprises a conjugated diene polymer chain having a vinyl bond content in the conjugated diene monomer unit portion of 1 to 40 mol% and containing 15 to 0 wt% of aromatic vinyl monomer units. And a modified conjugated diene rubber having a glass transition temperature of −110 to −40 ° C.
A rubber composition for base treads is provided.

  In the rubber composition for base tread, the modified conjugated diene rubber preferably accounts for 5 to 75% by weight in the rubber component.

  In the rubber composition for base tread, the modified conjugated diene rubber is preferably a modified butadiene rubber obtained by reacting the modifying agent with the active end of the 1,3-butadiene polymer chain having an active end.

  The base tread rubber composition preferably further contains natural rubber as a rubber component.

  The base tread rubber composition preferably further comprises 1.6 to 5.0 parts by weight of a crosslinking agent with respect to 100 parts by weight of the rubber component.

  Moreover, according to this invention, the tire by which a base tread is comprised with the crosslinked material of the rubber composition for base treads containing said crosslinking agent is provided.

  According to the present invention, it is possible to obtain a rubber composition for a base tread that is particularly excellent in low heat build-up, and by using this as a base tread material, a tire that is excellent in fuel efficiency can be obtained.

  The rubber composition for a base tread of the present invention contains a specific modified conjugated diene rubber as at least a part of the rubber component, and further contains silica.

  The modified conjugated diene rubber used in the present invention has an epoxy group and / or a hydrocarbyloxysilyl group in the molecule at the active end of the conjugated diene polymer chain having an active end, and the number of epoxy groups in the molecule and the hydrocarbyloxy group. It is obtained by reacting a modifier having a total number of silyl groups of 2 or more, and its glass transition temperature needs to be −110 to −40 ° C.

  The polymer chain constituting the modified conjugated diene rubber is not particularly limited as long as it is a polymer chain comprising a conjugated diene monomer unit, but the homopolymer chain of the conjugated diene monomer or the conjugated diene monomer and the aromatic chain. It is preferably a copolymer chain with an aromatic vinyl monomer, and is a polymer chain composed of 70 to 100% by weight of a conjugated diene monomer unit and 30 to 0% by weight of an aromatic vinyl monomer unit. More preferably, it is particularly preferably a polymer chain composed of 83 to 100% by weight of conjugated diene monomer units and 17 to 0% by weight of aromatic vinyl monomer units, and is a homopolymer chain of conjugated diene monomers. Most preferably it is.

  Examples of the conjugated diene monomer used for constituting the modified conjugated diene rubber include 1,3-butadiene, isoprene (2-methyl-1,3-butadiene), 2,3-dimethyl-1,3- Examples thereof include butadiene, 2-chloro-1,3-butadiene, 1,3-pentadiene, and 1,3-hexadiene. Among these, it is preferable to use 1,3-butadiene and / or isoprene, and it is particularly preferable to use 1,3-butadiene. These conjugated diene monomers can be used alone or in combination of two or more.

  Examples of the aromatic vinyl monomer that can be used to constitute the modified conjugated diene rubber include styrene, α-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 2-ethylstyrene, 3-ethylstyrene, 4-ethylstyrene, 2,4-diisopropylstyrene, 2,4-dimethylstyrene, 4-t-butylstyrene, 5-t-butyl-2-methylstyrene, vinylnaphthalene, dimethylaminomethylstyrene, Examples include dimethylaminoethylstyrene. Among these, it is preferable to use at least one selected from styrene, α-methylstyrene, and 4-methylstyrene, and it is particularly preferable to use styrene. These aromatic vinyl monomers can be used alone or in combination of two or more.

  Further, the modified conjugated diene rubber used in the present invention is constituted by using other monomers in addition to the conjugated diene monomer and the aromatic vinyl monomer within the range that does not substantially impair the effects of the present invention. May be. Examples of other monomers include ethylenically unsaturated carboxylic acid ester monomers such as isopropyl (meth) acrylate, n-butyl (meth) acrylate, and t-butyl (meth) acrylate; ethylene, propylene, isobutylene, Examples thereof include olefin monomers such as vinylcyclohexane; non-conjugated diene monomers such as 1,4-pentadiene and 1,4-hexadiene. The amount of monomer units composed of these monomers is preferably 10% by weight or less, more preferably 5% by weight or less based on the weight of all monomer units, and substantially 0% by weight. % Is most preferred.

  In order to obtain the modified conjugated diene rubber used in the present invention, it is necessary to obtain a conjugated diene polymer chain having an active end using at least one conjugated diene monomer. In order to obtain a conjugated diene polymer chain having an active end, a monomer may be polymerized using a polymerization initiator in an inert solvent. The inert solvent used is not particularly limited as long as it is usually used in solution polymerization and does not inhibit the polymerization reaction. Specific examples thereof include, for example, aliphatic hydrocarbons such as butane, pentane, hexane, and 2-butene; alicyclic hydrocarbons such as cyclopentane, cyclohexane, and cyclohexene; aromatic carbonization such as benzene, toluene, and xylene. Hydrogen; These inert solvents can be used alone or in admixture of two or more. The amount of the inert solvent used is such that the monomer concentration is usually 1 to 50% by weight, preferably 10 to 40% by weight.

  The polymerization initiator is not particularly limited as long as it can polymerize a monomer to give a polymer having an active end, for example, an organic alkali metal compound and an organic alkaline earth metal compound, A polymerization initiator having a lanthanum series metal compound as a main catalyst is preferably used. Specific examples of the organic alkali metal compound include, for example, organic monolithium compounds such as n-butyllithium, sec-butyllithium, t-butyllithium, hexyllithium, phenyllithium, stilbenelithium; dilithiomethane, 1,4-dilithiobutane, Examples thereof include organic polyvalent lithium compounds such as 1,4-dilithio-2-ethylcyclohexane and 1,3,5-trilithiobenzene; organic sodium compounds such as sodium naphthalene; and organic potassium compounds such as potassium naphthalene. Examples of the organic alkaline earth metal compound include n-butylmagnesium, n-hexylmagnesium, ethoxycalcium, calcium stearate, t-butoxystrontium, ethoxybarium, isopropoxybarium, ethylmercaptobarium, t-butoxybarium, and phenoxybarium. , Diethylamino barium, barium stearate, ketyl barium and the like. As a polymerization initiator using a lanthanum series metal compound as a main catalyst, a lanthanum series metal salt composed of a lanthanum series metal such as lanthanum, cerium, praseodymium, neodymium, samarium, gadolinium, carboxylic acid, phosphorus-containing organic acid, etc. is used as a main catalyst. And a polymerization initiator comprising this and a promoter such as an alkylaluminum compound, an organoaluminum hydride compound, and an organoaluminum halide compound. Among these polymerization initiators, it is preferable to use an organic lithium compound, particularly an organic monolithium compound. In addition, the organic alkali metal compound includes a secondary amine such as dibutylamine, dihexylamine, dibenzylamine, pyrrolidine, hexamethyleneimine, heptamethyleneimine (preferably pyrrolidine, hexamethyleneimine, heptamethyleneimine) and the like. You may make it react and use as an organic alkali metal amide compound. These polymerization initiators can be used alone or in combination of two or more.

  The amount of the polymerization initiator used is usually in the range of 1 to 50 mmol, preferably 2 to 20 mmol, more preferably 4 to 15 mmol per 1000 g of the monomer used.

  When polymerizing the monomer, the polymerization temperature is usually in the range of −78 to + 150 ° C., preferably 0 to 100 ° C., more preferably 30 to 90 ° C. As the polymerization mode, any mode such as batch mode or continuous mode can be adopted.

  In order to adjust the vinyl bond content in the conjugated diene monomer unit in the conjugated diene polymer chain having an active end, it is preferable to add a polar compound to an inert solvent during the polymerization. Examples of the polar compound include ether compounds of dibutyl ether, tetrahydrofuran and ditetrahydrofurylpropane; tertiary amines such as tetramethylethylenediamine; alkali metal alkoxides; phosphine compounds. Among these, ether compounds and tertiary amines are preferable, and tetramethylethylenediamine is particularly preferable. The amount of the polar compound used is preferably in the range of 0.01 to 100 mol, more preferably 0.3 to 30 mol, with respect to 1 mol of the polymerization initiator. When the amount of the polar compound used is within this range, it is easy to adjust the vinyl bond content in the conjugated diene monomer unit, and problems due to deactivation of the polymerization initiator hardly occur.

  The weight average molecular weight of the conjugated diene polymer chain having an active end used for obtaining the modified conjugated diene rubber is preferably 50,000 to 1,500,000, and preferably 100,000 to 600,000. Is more preferable, and 150,000 to 400,000 is particularly preferable.

  The molecular weight distribution represented by the ratio (Mw / Mn) of the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the conjugated diene polymer chain having an active end is preferably 1.01 to 4.0, more preferably Is 1.02-3.5, particularly preferably 1.03-3.0. A polymer having a molecular weight distribution value (Mw / Mn) that is too small is difficult to produce, and if the Mw / Mn is too large, the low exothermic property of the resulting composition may be inferior.

  The modified conjugated diene rubber used in the present invention has an epoxy group and / or a hydrocarbyloxysilyl group in the molecule at the active end of the conjugated diene polymer chain having the active end obtained as described above. It can be obtained by reacting a modifying agent in which the total number of epoxy groups and hydrocarbyloxysilyl groups is 2 or more. By using such a modifier, it is possible to obtain a rubber composition for a base tread that is excellent in low heat buildup. In addition, when the conjugated diene polymer chain having an active end reacts with a modifier having a hydrocarbyloxysilyl group, at least a part of the hydrocarbyl group in the modifier is eliminated, so that the silicon-polymer chain end is removed. When a bond is considered to be formed and the conjugated diene polymer chain having an active end reacts with a modifier having an epoxy group, at least a part of the epoxy group in the modifier is ring-opened, It is believed that carbon-polymer chain end bonds are formed.

  The modifier used in the present invention has an epoxy group and / or a hydrocarbyloxysilyl group in the molecule, and the total number of epoxy groups and hydrocarbyloxysilyl groups in the molecule is 2 or more. There is no particular limitation. That is, as the modifying agent used in the present invention, one having two or more epoxy groups in the molecule or one having two or more hydrocarbyloxysilyl groups in the molecule can be used. Those having one epoxy group and one hydrocarbyloxysilyl group can also be used. In the present invention, even a modifier having a structure in which two or more hydrocarbyloxy groups are bonded to one silicon atom is a modifier having two or more hydrocarbyloxysilyl groups. .

  Examples of the hydrocarbyloxysilyl group that can be contained in the modifier used in the present invention include, for example, alkoxysilyl groups such as methoxysilyl group, ethoxysilyl group, propoxysilyl group, butoxysilyl group, and aryloxysilyl groups such as phenoxysilyl group. Is mentioned.

  It is particularly preferably used as a modifier having an epoxy group and / or a hydrocarbyloxysilyl group in the molecule used in the present invention, and the total number of epoxy groups and hydrocarbyloxysilyl groups in the molecule is 2 or more. As a thing, the polyorganosiloxane represented by the following general formula (I), the polyorganosiloxane represented by the following general formula (II), the polyorganosiloxane represented by the following general formula (III), the following general formula ( IV) and hydrocarbyloxysilane represented by the following general formula (V).

Formula (I):

^(Wherein, R 1 to R ⁸ is an alkyl group or an aryl group having 6 to 12 carbon atoms having 1 to 6 carbon atoms, which may be different even identical to each other .X ¹ and ^{X 4} Is a group having 4 to 12 carbon atoms containing an alkoxyl group having 1 to 5 carbon atoms, an aryloxy group having 6 to 14 carbon atoms or an epoxy group, or an alkyl group having 1 to 6 carbon atoms or 6 to 12 carbon atoms. X ¹ and X ⁴ may be the same or different, and X ² contains an alkoxyl group having 1 to 5 carbon atoms, an aryloxy group having 6 to 14 carbon atoms, or an epoxy group X ³ is a group containing an alkylene glycol repeating unit of 2 to 20, m is an integer of 2 to 200, n is an integer of 0 to 200, and k is 0. It is an integer of ~ 200.)

General formula (II):

^(Wherein, R 9 ^{to R 16} is an alkyl group or an aryl group having 6 to 12 carbon atoms having 1 to 6 carbon atoms, which may be different even identical to each other ^.X 5 to X ⁸ Is a group having 4 to 12 carbon atoms containing an alkoxyl group having 1 to 5 carbon atoms, an aryloxy group having 6 to 14 carbon atoms or an epoxy group.

General formula (III):

^(Wherein, R 17 ^{to R 19} is an alkyl group or an aryl group having 6 to 12 carbon atoms having 1 to 6 carbon atoms, which may be different even identical to each other ^.X 9 ^{to X 11} Is a C 4-12 group containing a C 1-5 alkoxyl group, a C 6-14 aryloxy group or an epoxy group, and s is an integer of 1-18.

Formula (IV):

(In the formula, R ²⁰ is an alkylene group having 1 to 12 carbon atoms. R ^{21 to} R ²⁵ are an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, and these are the same as each other. And q may be 1 or 2, and r is an integer of 1 to 10.)

Formula (V):

(In the formula, R ²⁶ is an alkylene group having 1 to 12 carbon atoms. R ^{27 to} R ³⁰ are an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, and these are the same as each other. Or it may be different.)

In the polyorganosiloxane represented by the general formula (I), the alkyl group having 1 to 6 carbon atoms constituting R ^{1 to} R ⁸ , X ¹ and X ⁴ of the general formula (I) is, for example, a methyl group, Examples include an ethyl group, an n-propyl group, an isopropyl group, a butyl group, a pentyl group, a hexyl group, and a cyclohexyl group. Examples of the aryl group having 6 to 12 carbon atoms include a phenyl group and a methylphenyl group. Among these alkyl groups and aryl groups, a methyl group is particularly preferable.

In the polyorganosiloxane represented by the general formula (I), examples of the alkoxyl group having 1 to 5 carbon atoms that can constitute X ¹ , X ² and X ⁴ include a methoxy group, an ethoxy group, a propoxy group, and an isopropoxy group. Group, butoxy group and the like. Of these, a methoxy group or an ethoxy group is preferable.

In the polyorganosiloxane represented by the general formula (I), examples of the aryloxy group having 6 to 14 carbon atoms that can constitute X ¹ , X ² and X ⁴ include a phenoxy group and a tolyloxy group.

Further, in the polyorganosiloxane represented by the general formula (I), the group having 4 to 12 carbon atoms having an epoxy group that can constitute X ¹ , X ² and X ⁴ is represented by the following general formula (VI). Group to be used.
Formula (VI): ZYE

  In the formula, Z is an alkylene group having 1 to 10 carbon atoms or an alkylarylene group, Y is a methylene group, a sulfur atom or an oxygen atom, and E is a hydrocarbyl group having 2 to 10 carbon atoms having an epoxy group. Among these, Y is preferably an oxygen atom, Y is preferably an oxygen atom, and E is more preferably a glycidyl group, Z is an alkylene group having 3 carbon atoms, Y is an oxygen atom, and E is Those that are glycidyl groups are particularly preferred.

In the polyorganosiloxane represented by the general formula (I), as X ¹ and X ⁴ , among these, a group having 4 to 12 carbon atoms or an alkyl group having 1 to 6 carbon atoms containing an epoxy group is preferable, X ² is preferably a group having 4 to 12 carbon atoms containing an epoxy group. In the polyorganosiloxane represented by the general formula (I), X ³ , that is, a group containing 2 to 20 alkylene glycol repeating units is preferably a group represented by the following general formula (VII).
Formula (VII):

  In the formula, t is an integer of 2 to 20, P is an alkylene group or alkylarylene group having 2 to 10 carbon atoms, R is a hydrogen atom or a methyl group, and Q is an alkoxyl group having 1 to 10 carbon atoms. Or it is an aryloxy group. Among these, those in which t is an integer of 2 to 8, P is an alkylene group having 3 carbon atoms, R is a hydrogen atom, and Q is a methoxy group are preferable.

  In the polyorganosiloxane represented by the general formula (I), m is an integer of 2 to 200, preferably 3 to 200, more preferably 20 to 150, and particularly preferably 30 to 120. If this number is small, the processability and low heat build-up of the resulting composition may be inferior. Moreover, when this number is large, the production of the polyorganosiloxane itself becomes difficult, and the viscosity becomes too high, which may make the handling difficult.

  Moreover, in the polyorganosiloxane represented with general formula (I), n is an integer of 0-200, Preferably it is an integer of 0-150, More preferably, it is an integer of 0-120. k is an integer of 0 to 200, preferably an integer of 0 to 150, more preferably an integer of 0 to 120. The total number of m, n, and k is preferably 400 or less, more preferably 300 or less, and particularly preferably 250 or less. When this number is large, the production of the polyorganosiloxane itself becomes difficult, and the viscosity becomes too high, which may make the handling difficult.

  In the polyorganosiloxane represented by the general formula (II) and the general formula (III), an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, an alkoxyl group having 1 to 5 carbon atoms, carbon The group of 4 to 12 carbon atoms containing an aryloxy group of 6 to 14 and an epoxy group is the same as that described for the polyorganosiloxane of the general formula (I).

  In the alkoxysilane represented by the general formula (IV) and the general formula (V), the alkyl group having 1 to 6 carbon atoms and the aryl group having 6 to 12 carbon atoms are explained for the polyorganosiloxane of the general formula (I). It is the same as what I did. When the alkoxysilane represented by the general formula (IV) or the general formula (V) is used as a modifier, the alkoxysilyl group reacts with the active end of the conjugated diene polymer chain, so that the modifier is heavy. After the reaction, the nitrogen-silicon bond is cleaved by hydrolysis to form a primary amino group or a secondary amino group. That is, a structure in which the polymer chain and the primary amino group or the secondary amino group are bonded via an alkylene group containing a silicon atom is formed.

  Specific examples of the alkoxysilane represented by the general formula (IV) or the general formula (V) include N, N-bis (trimethylsilyl) aminopropylmethyldimethoxysilane, 1-trimethylsilyl-2,2-dimethoxy-1-aza. -2-silacyclopentane, N, N-bis (trimethylsilyl) aminopropyltrimethoxysilane, N, N-bis (trimethylsilyl) aminopropyltriethoxysilane, N, N-bis (trimethylsilyl) aminopropylmethyldiethoxysilane, N, N-bis (trimethylsilyl) aminoethyltrimethoxysilane, N, N-bis (trimethylsilyl) aminoethyltriethoxysilane, N, N-bis (trimethylsilyl) aminoethylmethyldimethoxysilane and N, N-bis (trimethylsilyl) Amino Eth It can be exemplified methyl diethoxy silane. Among these, it is particularly preferable to use N, N-bis (trimethylsilyl) -3-aminopropyltrimethoxysilane.

  As another example of the modifier having an epoxy group and / or a hydrocarbyloxysilyl group in the molecule used in the present invention, and the total number of epoxy groups and hydrocarbyloxysilyl groups in the molecule is 2 or more, , Tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, tetraphenoxysilane, tetratoluoxysilane, and other tetraalkoxysilane compounds; hexamethoxydisilane, hexaethoxydisilane, bis (trimethoxysilyl) methane, bis ( Triethoxysilyl) methane, bis (trimethoxysilyl) ethane, bis (triethoxysilyl) ethane, bis (trimethoxysilyl) propane, bis (triethoxysilyl) propane, bis (trimethoxysilyl) butane, bis (triethoxy) Silyl) butane, bis (trimethoxysilyl) heptane, bis (triethoxysilyl) heptane, bis (trimethoxysilyl) hexane, bis (triethoxysilyl) hexane, bis (trimethoxysilyl) benzene, bis (triethoxysilyl) Benzene, bis (trimethoxysilyl) benzene, bis (trimethoxysilyl) cyclohexane, bis (triethoxysilyl) cyclohexane, bis (trimethoxysilyl) octane, bis (triethoxysilyl) octane, bis (trimethoxysilyl) nonane, Hexalcohols such as bis (triethoxysilyl) nonane, bis (trimethoxysilyl) ethylene, bis (triethoxysilyl) ethylene, bis (trimethoxysilylethyl) benzene, bis (triethoxysilylethyl) benzene Sisilane compounds; methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, methyltributoxysilane, methyltriphenoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, ethyltripropoxysilane, ethyltributoxysilane, ethyltri Phenoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, dimethyldipropoxysilane, dimethyldibutoxysilane, dimethyldiphenoxysilane, diethyldimethoxysilane, diethyldiethoxysilane, diethyldipropoxysilane, diethyldibutoxysilane, diethyldiphenoxysilane Alkyl alkoxysilane compounds such as vinyltrimethoxysilane, vinyltriethoxysilane, vinyltripropoxysila Alkenylalkoxysilane compounds such as vinyltributoxysilane, vinyltriphenoxysilane, allyltrimethoxysilane, octenyltrimethoxysilane, divinyldimethoxysilane, styryltrimethoxysilane; phenyltrimethoxysilane, phenyltriethoxysilane, Arylalkoxysilane compounds such as phenyltripropoxysilane, phenyltributoxysilane, phenyltriphenoxysilane; trimethoxychlorosilane, triethoxychlorosilane, tripropoxychlorosilane, tributoxychlorosilane, triphenoxychlorosilane, dimethoxydichlorosilane, dipropoxydichlorosilane, Diphenoxydichlorosilane, trimethoxybromosilane, triethoxybromosilane, tripropo Sibromosilane, triphenoxybromosilane, dimethoxydibromosilane, diethoxydibromosilane, diphenoxydibromosilane, trimethoxyiodosilane, triethoxyiodosilane, tripropoxyiodosilane, triphenoxyiodosilane, dimethoxydiiodosilane, diethoxydiiodo Halogenoalkoxysilane compounds such as silane and dipropoxyiodosilane; halogenoalkylalkoxysilane compounds such as β-chloroethylmethyldimethoxysilane and γ-chloropropylmethyldimethoxysilane; β-nitroethylmethyldimethoxysilane and γ-nitropropylmethyldimethoxy Nitroalkylalkoxysilane compounds such as silane, 3-glycidoxyethyltrimethoxysilane, 3-glycidoxybutylpropyl Trimethoxysilane, 3-glycidoxybutyltrimethoxysilane, 3-glycidoxypropyltripropoxysilane, 3-glycidoxypropyltributoxysilane, 3-glycidoxypropyltriphenoxysilane, 3-glycidoxypropyl Triphenoxysilane, 3-glycidoxypropylethyldimethoxysilane, 3-glycidoxypropylethyldiethoxysilane, 3-glycidoxypropylethyldiethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidyl Sidoxypropylmethyldipropoxysilane, 3-glycidoxypropylmethyldiphenoxysilane, 3-glycidoxypropyldimethylmethoxysilane, 3-glycidoxypropyldiethylethoxysilane, 3-glycidoxypropyldimethyle Xysilane, 3-glycidoxypropyldimethylphenoxysilane, 3-glycidoxypropyldiethylmethoxysilane, 3-glycidoxypropylmethyldiisopropeneoxysilane, bis (3-glycidoxypropyl) dimethoxysilane, bis (3 -Glycidoxypropyl) diethoxysilane, bis (3-glycidoxypropyl) dipropoxysilane, bis (3-glycidoxypropyl) dibutoxysilane, bis (3-glycidoxypropyl) diphenoxysilane, bis (3-glycidoxypropyl) methylmethoxysilane, bis (3-glycidoxypropyl) methylethoxysilane, bis (3-glycidoxypropyl) methylpropoxysilane, bis (3-glycidoxypropyl) methylbutoxysilane Bis (3-glycidoxip Pyr) methylphenoxysilane, tris (3-glycidoxypropyl) methoxysilane, β- (3,4-epoxycyclohexyl) ethyl-trimethoxysilane, β- (3,4-epoxycyclohexyl) ethyl-triethoxysilane, β- (3,4-epoxycyclohexyl) ethyl-tripropoxysilane, β- (3,4-epoxycyclohexyl) ethyl-tributoxysilane, β- (3,4-epoxycyclohexyl) ethyl-triphenoxysilane, β- (3,4-epoxycyclohexyl) propyl-trimethoxysilane, β- (3,4-epoxycyclohexyl) ethyl-methyldimethoxysilane, β- (3,4-epoxycyclohexyl) ethyl-ethyldimethoxysilane, β- (3 , 4-Epoxycyclohexyl) ethyl-eth Rudiethoxysilane, β- (3,4-epoxycyclohexyl) ethyl-methyldiethoxysilane, β- (3,4-epoxycyclohexyl) ethyl-methyldipropoxysilane, β- (3,4-epoxycyclohexyl) ethyl- Methyldibutoxysilane, β- (3,4-epoxycyclohexyl) ethyl-methyldiphenoxysilane, β- (3,4-epoxycyclohexyl) ethyl-dimethylmethoxysilane, β- (3,4-epoxycyclohexyl) ethyl- Diethylethoxysilane, β- (3,4-epoxycyclohexyl) ethyl-dimethylethoxysilane, β- (3,4-epoxycyclohexyl) ethyl-dimethylpropoxysilane, β- (3,4-epoxycyclohexyl) ethyl-dimethylbutoxy Silane, β- (3,4-D Xylcyclohexyl) ethyl-dimethylphenoxysilane, β- (3,4-epoxycyclohexyl) ethyl-diethylmethoxysilane, β- (3,4-epoxycyclohexyl) ethyl-methyldiisopropeneoxysilane, 2,3-epoxypropyl Epoxy group-containing alkoxysilanes such as methyldimethoxysilane, 3,4-epoxybutylmethyldimethoxysilane, 4,5-epoxyheptylmethyldimethoxysilane, 4,5-epoxyheptylethyldimethoxysilane, 5,6-epoxyhexylmethyldimethoxysilane Compound: 3-octathio-1-propyl-triethoxysilane, bis (3- (triethoxysilyl) propyl) disulfide, bis (3- (triethoxysilyl) propyl) tetrasulfide, γ-trimethoxysilane Sulfur-containing alkoxysilane compounds such as rylpropyldimethylthiocarbamyltetrasulfide and γ-trimethoxysilylpropylbenzothiazyltetrasulfide; bis (3-trimethoxysilylpropyl) methylamine, bis (3-triethoxysilylpropyl) methyl Amine, bis (3-trimethoxysilylpropyl) ethylamine, bis (3-trimethoxysilylpropyl) propylamine, bis (3-trimethoxysilylpropyl) butylamine, bis (3-triethoxysilylpropyl) ethylamine, bis (3 -Triethoxysilylpropyl) propylamine, bis (3-triethoxysilylpropyl) butylamine, bis (3-trimethoxysilylpropyl) phenylamine, bis (3-trimethoxysilylpropyl) ben Ruamine, bis (3-triethoxysilylpropyl) phenylamine, bis (3-triethoxysilylpropyl) benzylamine, tris (3-trimethoxysilylpropyl) amine, tris (3-triethoxysilylpropyl) amine, bis ( Trimethoxysilylmethyl) methylamine, bis (2-trimethoxysilylethyl) methylamine, bis (triethoxysilylmethyl) methylamine, bis (2-triethoxysilylethyl) methylamine, bis (triethoxysilylmethyl) propyl Amine, bis (2-triethoxysilylethyl) propylamine, tris (trimethoxysilylmethyl) amine, tris (2-triethoxysilylethyl) amine, N- (β-aminoethyl) -γ-aminopropyltrimethoxysilane Ami Group-containing alkoxysilane compound; bis [3- (trimethoxysilyl) propyl] urea, bis [3- (triethoxysilyl) propyl] urea, tris (3-trimethoxysilylpropyl) isocyanurate, tris (3-triethoxy Isocyanate group-containing alkoxysilane compounds such as silylpropyl) isocyanurate; tetraglycidyl-1,3-bisaminomethylcyclohexane, tetraglycidyl-1,3-bisaminomethylbenzene, epoxidized polybutadiene, epoxidized soybean oil, epoxidized flaxseed And epoxy group-containing compounds such as oil.

  The amount of the modifying agent used in the present invention is not particularly limited, but the amount is such that the ratio of the number of moles of conjugated diene polymer chain having an active end to the number of moles of the modifying agent is 0.9 to 1,000. It is preferable that the ratio is 1.1 to 400, and more preferable.

The timing when the modifier is reacted with the conjugated diene polymer chain having an active end is preferably when the polymerization reaction is almost completed, and after the polymerization reaction is almost completed, the conjugated diene polymer chain having an active end is a side reaction. It is preferably before the polymerization or the chain transfer reaction due to impurities in the polymerization system.

  The conditions for reacting the modifier with the conjugated diene polymer chain having an active end are usually in the range of 0 to 100 ° C., preferably 30 to 90 ° C., and the reaction time is usually 1 to 120 minutes. The range is preferably 2 to 60 minutes.

  After the modifier is reacted with the conjugated diene polymer chain having an active end, it is preferable to deactivate the active end by adding an alcohol such as methanol or isopropanol or water. In addition, if the conjugated diene polymer chain having an active end remains even after the modifier is reacted with the conjugated diene polymer chain having an active end, it is desired to deactivate the active end before deactivating the active end. Thus, other than the specific modifier used in the present invention, a polymerization terminal modifier, a coupling agent, and the like may be added and reacted in the polymerization system.

  After deactivating the active end of the polymer chain, anti-aging agents such as phenol-based stabilizers, phosphorus-based stabilizers, sulfur-based stabilizers, crumbizing agents, scale inhibitors, etc. were added to the polymerization solution as desired. Thereafter, the polymerization solvent is separated from the polymerization solution by direct drying or steam stripping, and the modified conjugated diene rubber is recovered. Before separating the polymerization solvent from the polymerization solution, an extending oil may be mixed into the polymerization solution, and the modified conjugated diene rubber may be recovered as an oil-extended rubber.

  As the extender oil used when recovering the modified conjugated diene rubber as an oil-extended rubber, those usually used in the rubber industry can be used, paraffinic, aromatic, naphthenic petroleum softeners, plant softeners, Examples include fatty acids. When using a petroleum softener, the polycyclic aromatic content is preferably less than 3%. This content is measured by the method of IP346 (the testing method of THE INSTITUTE PETROLEUM, UK). When using extending oil, the usage-amount is 5-100 weight part normally with respect to 100 weight part of modified conjugated diene rubbers, Preferably it is 10-60 weight part, More preferably, it is 20-50 weight part.

  The glass transition temperature of the modified conjugated diene rubber used in the present invention needs to be −110 to −40 ° C., preferably −110 to −45 ° C., more preferably −100 to −55 ° C., It is particularly preferably −95 to −70 ° C. By using the modified conjugated diene rubber having such a glass transition temperature, the low exothermic property of the resulting composition becomes good.

  The modified conjugated diene rubber used in the present invention has an epoxy group and / or a hydrocarbyloxysilyl group in the molecule at the active end of the 1,3-butadiene polymer chain having an active end, and the number of epoxy groups in the molecule Particularly preferred is a modified butadiene rubber obtained by reacting a modifier having a total number of hydrocarbyloxysilyl groups of 2 or more. By using a modified butadiene rubber as the modified conjugated diene rubber, the low exothermic property of the resulting composition becomes particularly good.

  The vinyl bond content in the conjugated diene monomer unit portion of the modified conjugated diene rubber used in the present invention is not particularly limited, but is usually 1 to 95 mol%, preferably 5 to 50 mol%, preferably 8 to More preferably, it is 40 mol%. By setting the vinyl bond content within this range, the low exothermic property of the resulting composition becomes better.

  The cis 1,4 bond content in the conjugated diene monomer unit portion of the modified conjugated diene rubber used in the present invention is not particularly limited, and is usually 8 to 99 mol%, preferably 20 to 98 mol%. More preferably, it is 25-40 mol%. By setting the cis 1,4 bond content within this range, the low exothermic property of the resulting composition becomes particularly good.

  The modified conjugated diene rubber used in the present invention preferably contains one in which two or more conjugated diene polymer chains are bonded via a modifier. In particular, those having a structure in which two or more conjugated diene polymer chains are bonded via a modifier preferably occupy 2 to 90% by weight, and 5 to 80% by weight based on the whole modified conjugated diene rubber. It is particularly preferred to occupy. Such a modified conjugated diene rubber has good coagulation and drying properties at the time of production, and further, when silica is blended, gives a composition that is more excellent in processability and low heat build-up. The ratio of those having a structure in which two or more conjugated diene polymer chains are bonded via a modifier (in the following description, sometimes referred to as a coupling rate) is the ratio of the finally obtained modified conjugated diene rubber. It is assumed that the weight fraction of polymer molecules having a molecular weight of 1.9 times or more of the weight average molecular weight of the conjugated diene polymer chain having an active end before reacting with the modifier with respect to the total amount. It shall be performed by permeation chromatography (polystyrene conversion).

  The weight average molecular weight of the modified conjugated diene rubber used in the present invention is not particularly limited, but is usually 100,000 to 3,000,000, preferably 150,000 as a value measured by gel permeation chromatography in terms of polystyrene. To 1,000,000, more preferably 200,000 to 600,000. If the molecular weight is too high, it is difficult to add silica to the modified conjugated diene rubber, and the processability of the composition may be inferior. Moreover, when molecular weight is too low, there exists a possibility that the low exothermic property of the composition obtained may be inferior.

  The molecular weight distribution represented by the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the modified conjugated diene rubber used in the present invention is preferably 1.1 to 3.0, more preferably 1 .2 to 2.5, particularly preferably 1.3 to 2.2. When the molecular weight distribution value (Mw / Mn) is too large, the low exothermic property of the resulting composition may be inferior.

The Mooney viscosity (ML _{1 + 4} , 100 ° C.) of the modified conjugated diene rubber used in the present invention is also not particularly limited, but is usually appropriately selected in the range of 20 to 100, preferably 30 to 85, more preferably 40 to 70. The When the modified conjugated diene rubber is an oil-extended rubber, the Mooney viscosity of the oil-extended rubber is preferably in the above range.

  The rubber composition for a base tread of the present invention comprises 100 parts by weight of a rubber component containing the specific modified conjugated diene rubber obtained as described above and 10 to 60 parts by weight of silica.

  The rubber component of the rubber composition for a base tread preferably contains other rubber than the modified conjugated diene rubber specified in the present invention. Other rubbers include, for example, natural rubber, polyisoprene rubber, emulsion-polymerized styrene-butadiene copolymer rubber, solution-polymerized styrene-butadiene copolymer rubber, polybutadiene rubber (polybutadiene containing crystal fibers made of 1,2-polybutadiene polymer) Styrene-isoprene copolymer rubber, butadiene-isoprene copolymer rubber, styrene-isoprene-butadiene copolymer rubber, acrylonitrile-butadiene copolymer rubber, acrylonitrile-styrene-butadiene copolymer rubber, and the like. . Of these, natural rubber, polyisoprene rubber, polybutadiene rubber, and styrene-butadiene copolymer rubber are preferably used. These rubbers can be used alone or in combination of two or more.

  In the rubber composition for a base tread of the present invention, the modified conjugated diene rubber of the present invention preferably occupies 5 to 75% by weight, more preferably 10 to 65% by weight in the rubber component, and more preferably 20 to 45%. It is particularly preferred to account for% by weight. By using the modified conjugated diene rubber at such a ratio, it is possible to obtain a composition that has good moldability when molded into a base tread and is particularly excellent in low heat buildup.

  Moreover, it is preferable that the rubber composition for base treads of this invention contains natural rubber as a rubber component. By using a combination of the modified conjugated diene rubber specific to the present invention and natural rubber, it is possible to obtain a composition that has good moldability when molded into a base tread and is particularly excellent in low heat buildup. In the rubber composition for a base tread, the natural rubber preferably occupies 10 to 95% by weight of the rubber component, more preferably 20 to 90% by weight, and particularly preferably 30 to 80% by weight. .

  In the rubber composition for a base tread of the present invention, it is necessary to contain 10 to 60 parts by weight of silica with respect to 100 parts by weight of the rubber component, preferably 15 to 50 parts by weight, and preferably 20 to 40 parts by weight. It is more preferable to contain part. By using silica in such an amount, the low exothermic property of the rubber composition becomes particularly good. Examples of the silica used include dry method white carbon, wet method white carbon, colloidal silica, and precipitated silica. Among these, wet method white carbon mainly containing hydrous silicic acid is preferable. Alternatively, a carbon-silica dual phase filler in which silica is supported on the carbon black surface may be used. These silicas can be used alone or in combination of two or more.

Is (measured by the BET method according to ASTM D3037-81) nitrogen adsorption specific surface area of silica used is preferably 50 to 300 m ² / g, more preferably 80~220m ² / g, particularly preferably 100~170m ² / g. If it is within this range, a rubber composition for base tread having a lower exothermic property can be obtained. Moreover, it is preferable that the pH of a silica is less than pH 7, and it is more preferable that it is pH 5-6.9.

  From the viewpoint of further improving the low heat build-up, it is preferable to further add a silane coupling agent to the base tread rubber composition of the present invention. Examples of the silane coupling agent include vinyltriethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, N- (β-aminoethyl) -γ-aminopropyltrimethoxysilane, 3-octathio- 1-propyl-triethoxysilane, bis (3- (triethoxysilyl) propyl) disulfide, bis (3- (triethoxysilyl) propyl) tetrasulfide, γ-trimethoxysilylpropyldimethylthiocarbamyl tetrasulfide, γ- Examples include trimethoxysilylpropylbenzothiazyl tetrasulfide. Among these, from the viewpoint of avoiding scorch during kneading, one having 4 or less sulfur contained in one molecule is preferable. These silane coupling agents can be used alone or in combination of two or more. The blending amount of the silane coupling agent is preferably 0.1 to 30 parts by weight, more preferably 1 to 15 parts by weight with respect to 100 parts by weight of silica.

  The rubber composition for base tread of the present invention may contain carbon black such as furnace black, acetylene black, thermal black, channel black and graphite. When carbon black is used, it is preferable to use furnace black. Specific examples thereof include SAF, ISAF, ISAF-HS, ISAF-LS, IISAF-HS, HAF, HAF-HS, HAF-LS, T-HS, T-NS, MAF, FEF, etc. are mentioned. These carbon blacks can be used alone or in combination of two or more. The amount of carbon black is usually 120 parts by weight or less with respect to 100 parts by weight of the rubber component, and the total amount of silica and carbon black is 25 to 120 parts by weight with respect to 100 parts by weight of the rubber component. Preferably, the amount is 30 to 60 parts by weight, more preferably 35 to 50 parts by weight.

The nitrogen adsorption specific surface area (N ₂ SA) of carbon black is preferably 5 to 200 m ² / g, more preferably 20 to 130 m ² / g, particularly preferably 40 to 80 m ² / g, and dibutyl phthalate (DBP). The amount of adsorption is preferably 5 to 200 ml / 100 g, more preferably 50 to 160 ml / 100 g, and particularly preferably 70 to 130 ml / 100 g. Within this range, it is possible to obtain a composition that has good moldability when molded into a base tread and is particularly excellent in low heat buildup.

  The method of adding a filler such as silica or carbon black to the rubber composition for base tread is not particularly limited, and it is added to a solid rubber and kneaded (dry kneading method) or added to a rubber solution and solidified. A drying method (wet kneading method) or the like can be applied.

  In addition to the above components, the rubber composition for a base tread according to the present invention includes a crosslinking agent, a crosslinking accelerator, a crosslinking activator, an anti-aging agent, an activator, a process oil, a plasticizer, a lubricant, and a filler according to a conventional method. , Tackifiers, aluminum hydroxide and other compounding agents can be blended in the required amounts.

  Examples of the crosslinking agent include sulfur, sulfur halides, organic peroxides, quinonedioximes, organic polyvalent amine compounds, and alkylphenol resins having a methylol group. Of these, sulfur is preferably used. The amount of the crosslinking agent is preferably 1.6 to 5.0 parts by weight, more preferably 1.7 to 4.0 parts by weight, particularly preferably 100 parts by weight of the rubber component of the base tread rubber composition. Is 1.9 to 3.0.

  Examples of the crosslinking accelerator include N-cyclohexyl-2-benzothiazylsulfenamide, Nt-butyl-2-benzothiazolesulfenamide, N-oxyethylene-2-benzothiazolesulfenamide, N- Sulfenamide-based crosslinking accelerators such as oxyethylene-2-benzothiazole sulfenamide and N, N′-diisopropyl-2-benzothiazole sulfenamide; guanidines such as diphenylguanidine, diortolylguanidine, orthotolylbiguanidine Thiourea-based crosslinking accelerators; thiazole-based crosslinking accelerators; thiuram-based crosslinking accelerators; dithiocarbamic acid-based crosslinking accelerators; xanthogenic acid-based crosslinking accelerators; Of these, those containing a sulfenamide-based crosslinking accelerator are particularly preferred. These crosslinking accelerators are used alone or in combination of two 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, particularly preferably 1. relative to 100 parts by weight of the rubber component of the base tread rubber composition. 0 to 4.0 parts by weight.

  As the crosslinking activator, for example, higher fatty acids such as stearic acid, zinc oxide and the like can be used. The amount of the crosslinking activator is appropriately selected. The amount of the higher fatty acid is preferably 0.05 to 15 parts by weight, more preferably 100 parts by weight of the rubber component of the rubber composition for base tread. The blending amount of zinc oxide is preferably 0.05 to 10 parts by weight, more preferably 0.5 to 3 parts by weight with respect to 100 parts by weight of the total rubber.

  As the process oil, the same oil as the above-described extended oil of the modified conjugated diene rubber can be used. Examples of other compounding agents include activators such as diethylene glycol, polyethylene glycol, and silicone oil; fillers such as calcium carbonate, talc, and clay; tackifiers such as petroleum resins and coumarone resins; and waxes.

  In order to obtain the rubber composition for a base tread of the present invention, each component may be kneaded according to a conventional method. For example, after kneading a compounding agent excluding a crosslinking agent and a crosslinking accelerator and a rubber component, the kneaded product is crosslinked. The desired composition can be obtained by mixing an agent and a crosslinking accelerator. The kneading temperature of the compounding agent excluding the crosslinking agent and crosslinking accelerator and the rubber component is preferably 80 to 200 ° C, more preferably 120 to 180 ° C, and the kneading time is preferably 30 seconds to 30 minutes. Mixing of the kneaded material, the crosslinking agent and the crosslinking accelerator is usually performed after cooling to 100 ° C. or lower, preferably 80 ° C. or lower.

  The rubber composition for a base tread of the present invention is crosslinked and used as a tire base tread. That is, the tire of the present invention is a tire in which the base tread is constituted by a cross-linked product of the rubber composition for base tread. In particular, by using the rubber composition for a base tread of the present invention that is excellent in low heat build-up as a base tread, a tire that is excellent in fuel efficiency can be obtained.

  The method for molding the rubber composition for a base tread of the present invention into a tire tread is not particularly limited, and may be a conventional method. Specific examples thereof include a method for forming a rubber composition for a base tread of the present invention containing a cross-linking agent into a sheet shape, and bonding it to a separately formed sheet for a cap tread, or for a base tread of the present invention. There is a method in which a rubber composition and a composition for constituting a cap tread separately manufactured are integrally formed by multilayer extrusion molding. Further, the method for crosslinking these is not particularly limited, and a composition containing a crosslinking agent in a mold may be filled and heated to be crosslinked simultaneously with molding. After molding, it may be heated to crosslink. The crosslinking temperature is preferably 120 to 200 ° C, more preferably 140 to 180 ° C, and the crosslinking time is usually about 1 to 120 minutes.

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. In addition, unless otherwise indicated, the part and% in each example are a basis of weight.

Various physical properties were evaluated according to the following methods.
[Weight average molecular weight, molecular weight distribution and coupling rate]
A chart based on the molecular weight in terms of polystyrene was obtained by gel permeation chromatography, and the chart was obtained based on the chart. The specific measurement conditions for gel permeation chromatography are as follows.
Measuring instrument: HLC-8020 (manufactured by Tosoh Corporation)
Column: GMH-HR-H (manufactured by Tosoh Corporation) connected in series Detector: Differential refractometer RI-8020 (manufactured by Tosoh Corporation)
Eluent: Tetrahydrofuran Column temperature: 40 ° C
[Styrene unit content and vinyl bond content]
^It was measured by ¹ H-NMR.
[Mooney viscosity (ML _{1 + 4} , 100 ° C)]
According to JIS K6300, it measured using the Mooney viscometer (made by Shimadzu Corp.).
〔Glass-transition temperature〕
Using a differential scanning calorimeter (Perkin Elmer), the temperature was raised from 23 ° C. to 120 ° C., held at 120 ° C. for 10 minutes, cooled to −120 ° C. (cooling rate 100 ° C./min), and −120 ° C. was changed to 10 The temperature of the measurement sample was changed in the order of holding for minutes and raising the temperature to 23 ° C. (heating rate 10 ° C./min), and the average value of the onset value twice was used as the measured value of the glass transition temperature.
[Low heat generation]
Using a viscoelasticity measuring device EPLEXOR manufactured by GABO, tan δ at 60 ° C. was measured under conditions of initial strain of 0.5%, dynamic strain of 1% and 10 Hz. About this characteristic, it showed with the index | exponent which sets the measured value of the sample of the comparative example 1 to 100. The smaller this index, the better the low heat buildup.

[Production Example 1]
An autoclave equipped with a stirrer was charged with 4000 g of cyclohexane, 600 g of 1,3-butadiene, and 0.10 mmol of tetramethylethylenediamine, and then n-butyllithium was an impurity that inhibits polymerization contained in cyclohexane and 1,3-butadiene. An amount necessary for neutralization was added, and 8.8 mmol was added as n-butyllithium for the polymerization reaction, and polymerization was started at 50 ° C. After 20 minutes from the start of polymerization, 400 g of 1,3-butadiene was continuously added over 30 minutes. The maximum temperature during the polymerization reaction was 80 ° C. After completion of the continuous addition, the polymerization reaction was continued for another 15 minutes, and after confirming that the polymerization conversion was in the range of 95% to 100%, a small amount of the polymerization solution was sampled. A small amount of the sampled polymerization solution was added with excess methanol to stop the reaction, and then air-dried to obtain a polymer, which was used as a sample for gel permeation chromatography analysis. For this sample (a conjugated diene polymer chain having an active end), the weight average molecular weight and molecular weight distribution were measured. These measurement results are shown in Table 1. Immediately after sampling a small amount of the polymerization solution, 0.29 mmol of polyorganosiloxane A represented by the following formula (VIII) was added in the form of a 20 weight percent concentration xylene solution, reacted for 30 minutes, and then the polymerization was stopped. As an agent, an amount of methanol corresponding to twice the mole of n-butyllithium used was added to obtain a solution containing a modified butadiene rubber. To this solution, Irganox 1520L (manufactured by Ciba Specialty Chemicals) as an anti-aging agent was added in an amount of 0.15 part to 100 parts of the modified butadiene rubber, and then the solvent was removed by steam stripping. For 24 hours to obtain a solid modified butadiene rubber I. The rubber was measured for weight average molecular weight, molecular weight distribution, coupling rate, vinyl bond content of butadiene unit, Mooney viscosity, and glass transition temperature. These measurement results are shown in Table 1.

[Production Example 2]
In an autoclave equipped with a stirrer, 4000 g of cyclohexane, 600 g of 1,3-butadiene, and 1.3 mmol of tetramethylethylenediamine were charged, and then n-butyllithium contained impurities that hindered polymerization contained in cyclohexane and 1,3-butadiene. The amount necessary for neutralization was added, and 7.4 mmol was added as the amount of n-butyllithium used for the polymerization reaction, and polymerization was started at 50 ° C. After 20 minutes from the start of polymerization, 400 g of 1,3-butadiene was continuously added over 30 minutes. The maximum temperature during the polymerization reaction was 80 ° C. After completion of the continuous addition, the polymerization reaction was continued for another 15 minutes, and after confirming that the polymerization conversion was in the range of 95% to 100%, a small amount of the polymerization solution was sampled. A small amount of the sampled polymerization solution was added with excess methanol to stop the reaction, and then air-dried to obtain a polymer, which was used as a sample for gel permeation chromatography analysis. For this sample (a conjugated diene polymer chain having an active end), the weight average molecular weight and molecular weight distribution were measured. These measurement results are shown in Table 1. Immediately after sampling a small amount of the polymerization solution, 1.1 mmol of N, N-bis (trimethylsilyl) -3-aminopropyltrimethoxysilane in the form of a 20 weight percent cyclohexane solution was allowed to react for 15 minutes. Furthermore, after adding 5.2 mmol of N, N-bis (trimethylsilyl) -3-aminopropyltrimethoxysilane and reacting for 30 minutes, it was used as a polymerization terminator in 2 times mole of n-butyllithium used. A corresponding amount of methanol was added to obtain a polymerization solution containing the modified butadiene rubber. To this solution, Irganox 1520L (manufactured by Ciba Specialty Chemicals) as an anti-aging agent was added in an amount of 0.15 part to 100 parts of the modified butadiene rubber, and then the solvent was removed by steam stripping. For 24 hours to obtain a solid modified butadiene rubber II. The rubber was measured for weight average molecular weight, molecular weight distribution, coupling rate, vinyl bond content of butadiene unit, Mooney viscosity, and glass transition temperature. These measurement results are shown in Table 1.

[Production Example 3]
An autoclave equipped with a stirrer was charged with 4000 g of cyclohexane, 60 g of styrene, 440 g of 1,3-butadiene, and 2.1 mmol of tetramethylethylenediamine, and then inhibited polymerization of n-butyllithium contained in cyclohexane and 1,3-butadiene. The amount necessary for neutralizing the impurities to be added was added, and 7.3 mmol was added as the amount of n-butyllithium used for the polymerization reaction, and the polymerization was started at 50 ° C. Ten minutes after the initiation of polymerization, 400 g of 1,3-butadiene was continuously added over 50 minutes. The maximum temperature during the polymerization reaction was 70 ° C. After completion of the continuous addition, the polymerization reaction was continued for another 15 minutes, and after confirming that the polymerization conversion was in the range of 95% to 100%, a small amount of the polymerization solution was sampled. A small amount of the sampled polymerization solution was added with excess methanol to stop the reaction, and then air-dried to obtain a polymer, which was used as a sample for gel permeation chromatography analysis. For this sample (a conjugated diene polymer chain having an active end), the weight average molecular weight and molecular weight distribution were measured. These measurement results are shown in Table 1. Immediately after sampling a small amount of the polymerization solution, 0.025 mmol of polyorganosiloxane B represented by the following formula (IX) was added in the form of a 20 weight percent concentration xylene solution, reacted for 30 minutes, and then the polymerization was stopped. As an agent, an amount of methanol corresponding to twice the mole of n-butyllithium used was added to obtain a solution containing a modified styrene butadiene copolymer rubber. Irganox 1520L (manufactured by Ciba Specialty Chemicals) as an anti-aging agent was added to this solution in an amount of 0.15 parts per 100 parts of the modified styrene butadiene copolymer rubber, and then the solvent was removed by steam stripping. And vacuum drying at 60 ° C. for 24 hours to obtain a solid modified styrene butadiene copolymer rubber III. The rubber was measured for weight average molecular weight, molecular weight distribution, coupling rate, styrene unit content, vinyl bond content in the butadiene unit portion, Mooney viscosity, and glass transition temperature. These measurement results are shown in Table 1.

[Production Example 4]
An autoclave equipped with a stirrer was charged with 4000 g of cyclohexane, 120 g of styrene, 480 g of 1,3-butadiene, and 2.1 mmol of tetramethylethylenediamine, and then inhibited polymerization of n-butyllithium contained in cyclohexane and 1,3-butadiene. The amount necessary for neutralizing the impurities to be added was added, and 7.1 mmol was added as the amount of n-butyllithium used for the polymerization reaction, and the polymerization was started at 50 ° C. After 10 minutes from the start of polymerization, 30 g of styrene and 370 g of 1,3-butadiene were continuously added over 50 minutes. The maximum temperature during the polymerization reaction was 70 ° C. After completion of the continuous addition, the polymerization reaction was continued for another 15 minutes, and after confirming that the polymerization conversion was in the range of 95% to 100%, a small amount of the polymerization solution was sampled. A small amount of the sampled polymerization solution was added with excess methanol to stop the reaction, and then air-dried to obtain a polymer, which was used as a sample for gel permeation chromatography analysis. For this sample (a conjugated diene polymer chain having an active end), the weight average molecular weight and molecular weight distribution were measured. These measurement results are shown in Table 1. Immediately after sampling a small amount of the polymerization solution, 0.12 mmol of polyorganosiloxane A represented by the above formula (VIII) was added in the form of a 20 weight percent concentration xylene solution, reacted for 15 minutes, and then After adding 4.5 mmol of N, N-bis (trimethylsilyl) -3-aminopropyltrimethoxysilane in the form of a 20 weight percent cyclohexane solution, the mixture was reacted for 30 minutes, and then used as a polymerization terminator. An amount of methanol corresponding to 2 moles of butyl lithium was added to obtain a solution containing a modified styrene butadiene copolymer rubber. Irganox 1520L (manufactured by Ciba Specialty Chemicals) as an anti-aging agent was added to this solution in an amount of 0.15 parts per 100 parts of the modified styrene butadiene copolymer rubber, and then the solvent was removed by steam stripping. And vacuum drying at 60 ° C. for 24 hours to obtain a solid modified styrene butadiene copolymer rubber IV. The rubber was measured for weight average molecular weight, molecular weight distribution, coupling rate, styrene unit content, vinyl bond content in the butadiene unit portion, Mooney viscosity, and glass transition temperature. These measurement results are shown in Table 1.

[Comparative Production Example 1]
An autoclave equipped with a stirrer was charged with 4000 g of cyclohexane, 160 g of styrene, 440 g of 1,3-butadiene, and 5.1 mmol of tetramethylethylenediamine, and then inhibited polymerization of n-butyllithium contained in cyclohexane and 1,3-butadiene. The amount necessary for neutralizing the impurities to be added was added, and 6.1 mmol was added as the amount of n-butyllithium used for the polymerization reaction, and the polymerization was started at 40 ° C. After 10 minutes from the start of polymerization, 40 g of styrene and 360 g of 1,3-butadiene were continuously added over 50 minutes. The maximum temperature during the polymerization reaction was 65 ° C. After completion of the continuous addition, the polymerization reaction was continued for another 15 minutes, and after confirming that the polymerization conversion was in the range of 95% to 100%, a small amount of the polymerization solution was sampled. A small amount of the sampled polymerization solution was added with excess methanol to stop the reaction, and then air-dried to obtain a polymer, which was used as a sample for gel permeation chromatography analysis. For this sample (a conjugated diene polymer chain having an active end), the weight average molecular weight and molecular weight distribution were measured. These measurement results are shown in Table 1. Immediately after sampling a small amount of the polymerization solution, 0.021 mmol of polyorganosiloxane B represented by the above formula (IX) was added in the form of a 20 weight percent concentration xylene solution, reacted for 30 minutes, and then the polymerization was stopped. As an agent, an amount of methanol corresponding to twice the mole of n-butyllithium used was added to obtain a solution containing a modified styrene butadiene copolymer rubber. Irganox 1520L (manufactured by Ciba Specialty Chemicals) as an anti-aging agent was added to this solution in an amount of 0.15 parts per 100 parts of the modified styrene butadiene copolymer rubber, and then the solvent was removed by steam stripping. And vacuum drying at 60 ° C. for 24 hours to obtain a solid modified styrene butadiene copolymer rubber V. The rubber was measured for weight average molecular weight, molecular weight distribution, coupling rate, styrene unit content, vinyl bond content in the butadiene unit portion, Mooney viscosity, and glass transition temperature. These measurement results are shown in Table 1.

[Comparative Production Example 2]
In an autoclave equipped with a stirrer, 4000 g of cyclohexane, 600 g of 1,3-butadiene, and 0.07 mmol of tetramethylethylenediamine were charged, and then n-butyllithium contained impurities that hindered polymerization contained in cyclohexane and 1,3-butadiene. The amount necessary for neutralization was added, and 7.4 mmol was added as the amount of n-butyllithium used for the polymerization reaction, and polymerization was started at 50 ° C. After 20 minutes from the start of polymerization, 400 g of 1,3-butadiene was continuously added over 30 minutes. The maximum temperature during the polymerization reaction was 80 ° C. After completion of the continuous addition, the polymerization reaction was continued for another 15 minutes, and after confirming that the polymerization conversion was in the range of 95% to 100%, a small amount of the polymerization solution was sampled. A small amount of the sampled polymerization solution was added with excess methanol to stop the reaction, and then air-dried to obtain a polymer, which was used as a sample for gel permeation chromatography analysis. For this sample (a conjugated diene polymer chain having an active end), the weight average molecular weight and molecular weight distribution were measured. These measurement results are shown in Table 1. Immediately after sampling a small amount of the polymerization solution, 0.74 mmol of tin tetrachloride was added in the form of a 20 weight percent cyclohexane solution and allowed to react for 15 minutes, after which 4.8 mmol of N-methyl-2-pyrrolidone was added. After adding and reacting for 30 minutes, as a polymerization terminator, an amount of methanol corresponding to twice the mole of n-butyllithium used was added to obtain a solution containing polybutadiene rubber. Irganox 1520L (manufactured by Ciba Specialty Chemicals) as an anti-aging agent was added to this solution in an amount of 0.15 parts per 100 parts of polybutadiene rubber, and then the solvent was removed by steam stripping at 60 ° C. The solid polybutadiene rubber VI was obtained by vacuum drying for 24 hours. The rubber was measured for weight average molecular weight, molecular weight distribution, coupling rate, styrene unit content, vinyl bond content in the butadiene unit portion, Mooney viscosity, and glass transition temperature. These measurement results are shown in Table 1.

[Example 1]
In a Banbury mixer with a volume of 250 ml, 40 parts of the modified butadiene rubber I obtained in Production Example 1 and 60 parts of natural rubber were masticated for 30 seconds, and then silica I (trade name “Zeosil 1165MP”, manufactured by Rhodia, nitrogen adsorption specific surface area ( (BET method): 163 m ² / g) 35 parts, silane coupling agent (bis (3- (triethoxysilyl) propyl) disulfide, trade name “Si75”, manufactured by Degussa) 2.8 parts are added, After kneading for 1.5 minutes starting at ℃, carbon black (trade name “SEAST SO”, manufactured by Tokai Carbon Co., Ltd., nitrogen adsorption specific surface area (BET method): 42 m ² / g), 10 parts of process oil (trade name “ FUCKOL ERAMIC 30 ”, Shin Nippon Oil Co., Ltd. 5 parts, zinc oxide (Zinc Hua 1) 3 parts, stearic acid (trade name“ SA-300 ”) Asahi Denka Kogyo Co., Ltd.) 2 parts, anti-aging agent (N-phenyl-N ′-(1,3-dimethylbutyl) -p-phenylenediamine, trade name “NOCRACK 6C”, manufactured by Ouchi Shinsei Chemical Co., Ltd.) 2 And 2 parts of wax (trade name “Sannok”, manufactured by Ouchi Shinsei Chemical Co., Ltd.) were added, kneaded for 2.5 minutes, and the rubber composition was discharged from the Banbury mixer. The temperature of the rubber composition at the end of kneading was 150 ° C. The rubber composition was cooled to room temperature, kneaded again in a Banbury mixer for 3 minutes, and then the rubber composition was discharged from the Banbury mixer. Next, with an open roll at 50 ° C., the obtained rubber composition, 2 parts of sulfur and 1.5 parts of a crosslinking accelerator (Nt-butyl-2-benzothiazolylsulfenamide (trade name “Noxeller NS”) , Ouchi Shinsei Chemical Co., Ltd.) and diphenylguanidine (trade name “Noxeller D”, a mixture of Ouchi Shinsei Chemical Co., Ltd.) 0.5 parts), and a sheet-like rubber composition is taken out. It was. The rubber composition was press-crosslinked at 150 ° C. for 20 minutes to prepare a test piece, and the test piece was evaluated for low heat buildup. Table 2 shows the results. This evaluation is expressed as an index using the rubber composition of Comparative Example 1 as a reference sample (index 100).

(Footnote in Table 2)
* 1: Product name “Zeosil 1165MP”, manufactured by Rhodia, nitrogen adsorption specific surface area (BET method): 163 m ² / g
* 2: Product name “Zeosil 1115MP”, manufactured by Rhodia, nitrogen adsorption specific surface area (BET method): 112 m ² / g
* 3: Product name “Nipsil AQ”, manufactured by Tosoh Silica Corporation, nitrogen adsorption specific surface area (BET method): 198 m ² / g
* 4: Bis (3- (triethoxysilyl) propyl) disulfide, trade name “Si75”, manufactured by Degussa

[Example 2]
Instead of silica I, silica II (trade name “Zeosil 1115MP”, manufactured by Rhodia, nitrogen adsorption specific surface area (BET method): 112 m ² / g) was used, and the amount of the silane coupling agent was 1.8 parts. Except for this, a rubber composition was obtained in the same manner as in Example 1, and the test piece was evaluated. Table 2 shows the results.

Example 3
A rubber composition was obtained in the same manner as in Example 1 except that 40 parts of the modified butadiene rubber II obtained in Production Example 2 was used in place of the modified butadiene rubber I obtained in Production Example 1, and a test piece was obtained. Evaluation was performed. Table 2 shows the results.

Example 4
A rubber composition was obtained in the same manner as in Example 1 except that 40 parts of the modified styrene butadiene copolymer rubber III obtained in Production Example 3 was used instead of that obtained in Production Example 1, and the test piece was evaluated. Went. Table 2 shows the results.

Example 5
A rubber composition was obtained in the same manner as in Example 2 except that 40 parts of the modified styrene butadiene copolymer rubber IV obtained in Production Example 4 was used instead of the modified butadiene rubber I obtained in Production Example 1. The test piece was evaluated. Table 2 shows the results.

[Comparative Example 1]
A rubber composition was obtained in the same manner as in Example 1 except that 40 parts of the polybutadiene rubber VI obtained in Comparative Production Example 2 was used instead of the modified butadiene rubber I obtained in Production Example 1, and a test piece was obtained. Evaluation was performed. Table 2 shows the results.

[Comparative Example 2]
A rubber composition was obtained in the same manner as in Example 1, except that V40 parts of the modified styrene butadiene copolymer rubber obtained in Comparative Production Example 1 was used in place of the modified butadiene rubber I obtained in Production Example 1. The test piece was evaluated. Table 2 shows the results.

[Comparative Example 3]
Instead of silica I, silica III (trade name “Nipsil AQ”, manufactured by Tosoh Silica Co., Ltd., nitrogen adsorption specific surface area (BET method): 198 m ² / g) was used, and the amount of the silane coupling agent was 3.5 parts. Except for this, a rubber composition was obtained in the same manner as in Comparative Example 1, and the test piece was evaluated. Table 2 shows the results.

  Table 2 shows the following. That is, the rubber composition for base treads of the present invention is excellent in low heat buildup (Examples 1 to 5). In contrast, when the modified conjugated diene rubber to be blended (modified butadiene rubber) is not modified with the specific modifier of the present invention (Comparative Examples 1 and 3), the glass transition temperature of the blended modified conjugated diene rubber is When it is too high (Comparative Example 2), the rubber composition is inferior in low heat build-up compared to the rubber composition for base tread of the present invention. Therefore, it can be said that the rubber composition for a base tread of the present invention is excellent in low heat buildup, and a tire in which the base tread is composed of this composition is excellent in fuel efficiency.

Claims (6)

The active end of the conjugated diene polymer chain having an active terminal, a base tread comprising a rubber component 100 parts by weight containing modified conjugated diene rubber ing by reacting a denaturation agent, and a silica 10-60 parts by weight a use rubber composition,
The modifying agent is represented by the following general formula (I):

(In General Formula (I), R ^{1 to} R ⁸ are each an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, which may be the same or different from each other. X ¹ and X ⁴ are each an alkoxyl group having 1 to 5 carbon atoms, an aryloxy group having 6 to 14 carbon atoms, a group having 4 to 12 carbon atoms containing an epoxy group, an alkyl group having 1 to 6 carbon atoms, or a carbon number X ¹ and X ⁴ may be the same or different, and X ² is an alkoxyl group having 1 to 5 carbon atoms, an aryloxy group having 6 to 14 carbon atoms, or an epoxy. A group containing a group having 4 to 12 carbon atoms, X ³ is a group containing a repeating unit of 2 to 20 alkylene glycol, m is an integer of 2 to 200, n is an integer of 0 to 200, k is an integer of 0 to 200.)
Or the following general formula (IV):

(In General Formula (IV), R ²⁰ is an alkylene group having 1 to 12 carbon atoms. R ^{21 to} R ²⁵ are an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, These may be the same or different from each other, q is 1 or 2, and r is an integer of 1 to 10.)
A compound represented by
The modified conjugated diene rubber comprises a conjugated diene polymer chain having a vinyl bond content in the conjugated diene monomer unit portion of 1 to 40 mol% and containing 15 to 0 wt% of aromatic vinyl monomer units. And a modified conjugated diene rubber having a glass transition temperature of −110 to −40 ° C.
A rubber composition for a base tread characterized by the above . The rubber composition for a base tread according to claim 1, wherein the modified conjugated diene rubber is a modified butadiene rubber obtained by reacting the modifier with an active end of a 1,3-butadiene polymer chain having an active end. The rubber composition for a base tread according to claim 1 or 2 , wherein the modified conjugated diene rubber accounts for 5 to 75% by weight in the rubber component. The rubber composition for base treads according to any one of claims 1 to 3, further comprising natural rubber as a rubber component in an amount of 10 to 95% by weight based on the weight of the rubber component .   Furthermore, the rubber composition for base treads in any one of Claims 1-4 formed by containing 1.6-5.0 weight part of crosslinking agents with respect to 100 weight part of rubber components.   A tire comprising a base tread composed of a crosslinked product of the rubber composition for a base tread according to claim 5.