Rubber composition for tire and tire

Abstract

The present invention provides a tire rubber composition having low temperature dependence of rolling resistance and excellent wet performance, and a tire using the same. The composition of the present invention comprises a rubber component containing 35% by mass or greater of a specific conjugated diene rubber and 15% by mass or greater of a specific butadiene rubber, silica, and a silane coupling agent. The specific conjugated diene rubber comprises a block A containing isoprene units and a block B containing butadiene units, and has a modified structure formed at the terminal with a siloxane compound. At least one of A and B contains a unit of a vinyl compound containing a functional group capable of interacting with silica. The Mw of A is 1,000 to 30,000, the overall Mw is 50,000 to 5,000,000, the overall aromatic vinyl content is 30 to 45% by mass, the overall vinyl bond content is 15 to 35% by mass, and the specific butadiene rubber has a glass transition temperature of -85°C or less.

Description

Technical Field

[0001] The present invention relates to a rubber composition for a tire and a tire. Background Art

[0002] Conventionally, as a rubber composition used for tires, a composition containing a modified conjugated diene rubber and silica is known (for example, Patent Document 1).

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: International Publication No. 2019 / 073828 Summary of the Invention

[0006] Problems to be solved by the invention

[0007] Recently, as the required performance level increases, tires are required to have a lower temperature dependency on rolling resistance. In addition, as the required safety level increases, improvements in wet performance are also required.

[0008] Under such circumstances, the present inventors prepared a tire rubber composition with reference to Patent Document 1 and evaluated the temperature dependence of rolling resistance and wet performance of the resulting tire. As a result, it became clear that the composition did not necessarily meet the level currently required.

[0009] Therefore, in view of the above circumstances, an object of the present invention is to provide a rubber composition for a tire having low temperature dependence of rolling resistance and excellent wet performance when manufactured into a tire, and a tire manufactured using the rubber composition for a tire.

[0010] In addition, hereinafter, the temperature dependency of rolling resistance and the wet performance when the tire is produced are also simply referred to as the temperature dependency of rolling resistance and the wet performance.

[0011] Means for solving problems

[0012] The present inventors have conducted intensive studies on the above-mentioned problems and have found that the above-mentioned problems can be solved by using a specific modified conjugated diene rubber and a specific butadiene rubber in predetermined amounts, thereby completing the present invention.

[0013] That is, the present inventors have found that the above-mentioned problems can be solved by the following configuration.

[0014] (1) A rubber composition for a tire, comprising a rubber component, silica, and a silane coupling agent,

[0015] The rubber component contains a specific conjugated diene rubber and a specific butadiene rubber.

[0016] In the rubber component, the content of the specific conjugated diene rubber is 35% by mass or more, and the content of the specific butadiene rubber is 15% by mass or more.

[0017] The above-mentioned specific conjugated diene rubber is:

[0018] A conjugated diene rubber comprising a polymer block (A) containing an isoprene monomer unit and a polymer block (B) containing a 1,3-butadiene monomer unit, and having a modified structure formed with a siloxane compound at at least one terminal.

[0019] And the above-mentioned specific conjugated diene rubber is:

[0020] At least one of the polymer block (A) and the polymer block (B) contains a unit of a vinyl compound containing a functional group capable of interacting with silica,

[0021] The weight average molecular weight (Mw) of the polymer block (A) is in the range of 1,000 to 30,000, and the overall weight average molecular weight (Mw) is in the range of 50,000 to 5,000,000.

[0022] The total aromatic vinyl monomer unit content is 30 to 45% by mass.

[0023] A conjugated diene rubber having a total vinyl bond content of 15 to 35% by mass,

[0024] The specific butadiene rubber is a butadiene rubber having a glass transition temperature of -85°C or lower.

[0025] The content of the silica is 50 to 150 parts by mass relative to 100 parts by mass of the rubber component.

[0026] The content of the silane coupling agent is 3 to 30% by mass relative to the content of the silica.

[0027] (2) The rubber composition for a tire according to (1) above, wherein the aromatic vinyl monomer unit content of the specific conjugated diene rubber is 35 to 45% by mass.

[0028] (3) The rubber composition for a tire according to (1) or (2) above, wherein the specific butadiene rubber has a modified group containing a heteroatom at at least one terminal.

[0029] (4) The tire rubber composition according to any one of (1) to (3) above, wherein the silica contains a CTAB adsorption specific surface area of ​​190 m 2 / g or more of silica, that is, 20 parts by mass or more of specific silica.

[0030] (5) The tire rubber composition according to any one of (1) to (4) above, further comprising an alkyltriethoxysilane represented by the general formula (I) described below,

[0031] The content of the alkyltriethoxysilane is 2.0 to 15.0% by mass relative to the content of the silica.

[0032] (6) The rubber composition for a tire according to any one of (1) to (5) above, further comprising a liquid diene rubber having a weight average molecular weight of 3,000 or more,

[0033] The content of the liquid diene rubber is 1.0 to 15.0% by mass relative to the content of the silica.

[0034] (7) The rubber composition for a tire according to (6) above, wherein the liquid diene rubber has a functional group derived from a silane compound represented by the following general formula (II).

[0035] (8) The rubber composition for a tire according to any one of (1) to (7) above, further comprising a thermoplastic resin having a softening point of 50° C. or higher.

[0036] The content of the thermoplastic resin is 1 to 20 parts by mass relative to 100 parts by mass of the rubber component.

[0037] (9) A tire produced using the rubber composition for a tire according to any one of (1) to (8) above.

[0038] Effects of the Invention

[0039] As described below, the present invention can provide a rubber composition for a tire having low temperature dependence of rolling resistance and excellent wet performance when manufactured into a tire, and a tire manufactured using the rubber composition for a tire. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is a partial cross-sectional schematic diagram showing an example of an embodiment of the tire of the present invention. DETAILED DESCRIPTION

[0041] Hereinafter, the rubber composition for a tire of the present invention and a tire produced using the rubber composition for a tire will be described.

[0042] In addition, the numerical range expressed using "to" in this specification means a range including the numerical values ​​described before and after "to" as the lower limit and the upper limit.

[0043] In addition, each component contained in the tire rubber composition of the present invention may be used alone or in combination of two or more. Here, when two or more components are used in combination, the content of the component refers to the total content unless otherwise specified.

[0044] [A] Tire rubber composition

[0045] The rubber composition for a tire of the present invention (hereinafter also referred to as "the composition of the present invention") is the following rubber composition for a tire,

[0046] It contains rubber components, silica, and silane coupling agents.

[0047] The rubber component contains a specific conjugated diene rubber and a specific butadiene rubber.

[0048] In the rubber component, the content of the specific conjugated diene rubber is 35% by mass or more, and the content of the butadiene rubber is 15% by mass or more.

[0049] The above-mentioned specific conjugated diene rubber is:

[0050] A conjugated diene rubber comprising a polymer block (A) containing an isoprene monomer unit and a polymer block (B) containing a 1,3-butadiene monomer unit, and having a modified structure formed with a siloxane compound at at least one terminal.

[0051] And the above-mentioned specific conjugated diene rubber is:

[0052] At least one of the polymer block (A) and the polymer block (B) contains a unit of a vinyl compound containing a functional group capable of interacting with silica,

[0053] The weight average molecular weight (Mw) of the polymer block (A) is in the range of 1,000 to 30,000, and the weight average molecular weight (Mw) of the entire conjugated diene rubber is in the range of 50,000 to 5,000,000.

[0054] The aromatic vinyl monomer unit content is 30 to 45% by mass.

[0055] A conjugated diene rubber having a vinyl bond content of 15 to 35% by mass,

[0056] The specific butadiene rubber is a butadiene rubber having a glass transition temperature of -85°C or lower.

[0057] The content of the silica is 50 to 150 parts by mass relative to 100 parts by mass of the rubber component.

[0058] The content of the silane coupling agent is 3 to 30% by mass relative to the content of the silica.

[0059] Hereinafter, each component contained in the composition of the present invention will be described.

[0060] [I] Rubber component

[0061] The rubber component contained in the composition of the present invention includes a specific conjugated diene rubber and a specific butadiene rubber.

[0062] Here, in the rubber component, the content of the specific conjugated diene rubber is 35% by mass or more, and the content of the specific butadiene rubber is 15% by mass or more.

[0063] The rubber component may contain a rubber component (other rubber component) that does not correspond to any of the specific conjugated diene rubber and the specific butadiene rubber.

[0064] The rubber component is preferably in a solid state.

[0065] [1] Specific conjugated diene rubber

[0066] As described above, the rubber component contains the specific conjugated diene rubber.

[0067] The above-mentioned specific conjugated diene rubber is:

[0068] A conjugated diene rubber comprising a polymer block (A) containing an isoprene monomer unit and a polymer block (B) containing a 1,3-butadiene monomer unit, and having a modified structure formed with a siloxane compound at at least one terminal.

[0069] And the above-mentioned specific conjugated diene rubber is:

[0070] At least one of the polymer block (A) and the polymer block (B) contains a unit of a vinyl compound containing a functional group capable of interacting with silica,

[0071] The weight average molecular weight (Mw) of the polymer block (A) is in the range of 1,000 to 30,000, and the overall weight average molecular weight (Mw) is in the range of 50,000 to 5,000,000.

[0072] The total aromatic vinyl monomer unit content is 30 to 45% by mass.

[0073] A conjugated diene rubber having an overall vinyl bond content of 15 to 35% by mass.

[0074] Since the specific conjugated diene rubber has an aromatic vinyl monomer unit content of 30 to 45% by mass as a whole, at least one of the polymer block (A) and the polymer block (B) contains an aromatic vinyl monomer unit.

[0075] [Polymer block (A)]

[0076] The polymer block (A) is not particularly limited as long as it contains isoprene monomer units (preferably containing isoprene monomer units as the main component), and may be composed solely of isoprene monomer units or may be composed of isoprene monomer units and monomer units other than isoprene monomer units. In this case, suitable monomer units other than isoprene monomer units include aromatic vinyl monomer units. The polymer block (A) of the present invention preferably contains aromatic vinyl monomer units in addition to isoprene monomer units.

[0077] Isoprene monomer unit content

[0078] The content of isoprene monomer units in the polymer block (A) (isoprene monomer unit content) is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 90% by mass or more. Furthermore, the upper limit of the isoprene monomer unit content is not particularly limited, but is preferably 99% by mass or less. By setting the isoprene monomer unit content in the polymer block (A) to the above range, when a compounding agent such as silica is mixed with the conjugated diene rubber, the affinity of the conjugated diene rubber with the compounding agent such as silica can be further improved, thereby making the resulting cross-linked rubber have better low heat buildup properties.

[0079] [Vinyl bond content in isoprene monomer units]

[0080] The vinyl bond content of the isoprene monomer units in the polymer block (A) is preferably 3 to 90% by mass, more preferably 5 to 80% by mass. By adjusting the vinyl bond content of the isoprene monomer units within the above range, the low heat buildup properties of the resulting cross-linked rubber can be further improved. It should be noted that, in this specification, the vinyl bond content of the isoprene monomer units refers to the total amount of isoprene monomer units having a 1,2-structure and isoprene monomer units having a 3,4-structure in the isoprene monomer units.

[0081] [Aromatic vinyl compound for forming aromatic vinyl monomer units]

[0082] As aromatic vinyl compounds for forming aromatic vinyl monomer units, styrene, methylstyrene, ethylstyrene, tert-butylstyrene, α-methylstyrene, α-methyl-p-methylstyrene, chlorostyrene, bromostyrene, methoxystyrene, dimethylaminomethylstyrene, dimethylaminoethylstyrene, diethylaminomethylstyrene, diethylaminoethylstyrene, cyanoethylstyrene, vinylnaphthalene, etc. can be mentioned. Among them, styrene is preferred. The content of aromatic vinyl monomer units (e.g., styrene monomer units) in the polymer block (A) (aromatic vinyl monomer unit content) (e.g., styrene monomer unit content) is preferably 50% by mass or less, more preferably 30% by mass or less, and further preferably 10% by mass or less. In addition, the lower limit of the aromatic vinyl monomer unit content is not particularly limited, but is preferably 1% by mass or more.

[0083] [Units of a vinyl compound containing a functional group capable of interacting with silica]

[0084] In addition, the specific conjugated diene rubber contains units of a vinyl compound containing a functional group capable of interacting with silica in at least one of the polymer block (A) and the polymer block (B) described below. Hereinafter, the case where the polymer block (A) contains such units of a vinyl compound containing a functional group capable of interacting with silica will be described. However, the units of the vinyl compound containing a functional group capable of interacting with silica only need to be contained in at least one of the polymer block (A) and the polymer block (B) described below. Therefore, when the units of the vinyl compound containing a functional group capable of interacting with silica are contained in the polymer block (B) described below, they do not necessarily need to be contained in the polymer block (A).

[0085] <Vinyl compounds containing functional groups capable of interacting with silica>

[0086] As for forming the unit of the vinyl compound containing the functional group that can interact with silica, containing the vinyl compound that can interact with silica, as long as containing the functional group that can interact with silica and the compound of vinyl, it is not particularly limited.Here, the so-called functional group that can interact with silica, is to form a covalent bond between the functional group and the silica surface, or can form a functional group of intermolecular force (for example, ion-dipole interaction, dipole-dipole interaction, hydrogen bond, van der Waals force etc.) weaker than covalent bond.As such functional group that can interact with silica, it is not particularly limited, the functional group containing nitrogen atoms, the functional group containing silicon atoms, the functional group containing oxygen atoms etc. can be enumerated, among them, from the viewpoint of the high such interaction with silica, it is preferably a functional group containing silicon atoms.

[0087] (Suitable solution)

[0088] As a vinyl compound containing a silicon atom-containing functional group, which is a preferred embodiment of the vinyl compound containing a functional group capable of interacting with silica, for example, a compound represented by the following general formula (1) can be preferably used.

[0089]

[0090] In the above general formula (1), X 1 Represents a chemical single bond or alkylene group, X 2 、X 3 and X 4 Each independently represents a substituted amino group, a hydrocarbyloxy group, or a hydrocarbyl group which may have a substituent.

[0091] In the above general formula (1), X 1 It is a chemical single bond or a hydrocarbylene group, preferably a chemical single bond. Examples of the hydrocarbylene group include an alkylene group, an alkene diyl group, an arylene group, and a group in which an arylene group and an alkylene group are bonded.

[0092] Examples of alkylene groups include methylene, ethylene, and trimethylene. Examples of olefin diyl groups include vinylene and ethylene-1,1-diyl. Examples of arylene groups include phenylene, naphthylene, and biphenylene. Examples of groups in which an arylene group is bonded to an alkylene group include groups in which a phenylene group is bonded to a methylene group, and groups in which a phenylene group is bonded to an ethylene group. 1 In the case of an alkylene group, X 1 It is preferably an arylene group, and more preferably a phenylene group.

[0093] In the above general formula (1), X 2 、X 3 and X 4Each independently represents a substituted amino group, a hydrocarbyloxy group, or a hydrocarbyl group which may have a substituent. 2 、X 3 and X 4 Among them, at least one is a substituted amino group, more preferably X 2 、X 3 and X 4 Two of them are substituted amino groups.

[0094] As a component of X 2 、X 3 and X 4 As the substituted amino group, the group represented by the following general formula (2) is suitable.

[0095]

[0096] In the above general formula (2), R 1 and R 2 They may be combined or not combined with each other, in R 1 and R 2 When they are not combined with each other, R 1 and R 2 Each independently represents a hydrocarbon group which may have a substituent, or a trihydrocarbylsilyl group, in which R 1 With R 2 When combined with each other, R 1 and R 2 represents a hydrocarbylene group which may contain a nitrogen atom and / or an oxygen atom.

[0097] As a component of R 1 and R 2 Examples of the hydrocarbon group include chain alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, and -octyl; cyclic alkyl groups such as cyclopentyl and cyclohexyl; and aryl groups such as phenyl, benzyl, and naphthyl. Among these, chain alkyl groups are preferred, and methyl or ethyl groups are more preferred.

[0098] In the ability to constitute R 1 and R 2 When the hydrocarbon group has a substituent, examples include hydrocarbon groups having a hydrocarbon oxy group as a substituent, and examples of the hydrocarbon group having a hydrocarbon oxy group as a substituent include alkoxyalkyl groups such as methoxymethyl, ethoxymethyl, and methoxyethyl; aryloxyalkyl groups such as phenoxymethyl; and the like.

[0099] As a component of R 1 and R 2 Specific examples of the trihydrocarbylsilyl group include trialkylsilyl groups such as trimethylsilyl, triethylsilyl, and tert-butyldimethylsilyl.

[0100] In R 1 With R 2 When combined with each other, they can form R 1 and R 2 Examples of the alkylene group include trimethylene, tetramethylene, pentamethylene, hexamethylene, heptamethylene, octamethylene, decamethylene, dodecamethylene, 2,2,4-trimethylhexane-1,6-diyl and other alkylene groups; pentane-2-ene-1,5-diyl and other alkene diyl groups; etc. 1 and R 2 When the alkylene group 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-, a group represented by -CH=N-CH2-CH2-, a group represented by -CH2-CH2-O-CH2-CH2-, and the like.

[0101] R 1 and R 2 Preferably, an alkyl group, or R 1 With R 2 Combined with each other to form an alkylene group, R 1 and R 2 More preferably, it is an alkyl group, R 1 and R 2 More preferably, it is a methyl group or an ethyl group.

[0102] In the above general formula (2), R 1 and R 2 Specific examples of the group represented by the general formula (2) in the case of a hydrocarbon group include dialkylamino groups such as dimethylamino, diethylamino, ethylmethylamino, di-n-propylamino, diisopropylamino, di-n-butylamino, diisobutylamino, di-sec-butylamino, and di-tert-butylamino; and diarylamino groups such as diphenylamino. Among these, dialkylamino groups are preferred, and dimethylamino, diethylamino, and di-n-butylamino groups are more preferred.

[0103] In the above general formula (2), R 1 and R 2 Specific examples of the group represented by the general formula (2) in the case of a hydrocarbon group having a hydrocarbonoxy group as a substituent include di(alkoxyalkyl)amino groups such as di(methoxymethyl)amino and di(ethoxymethyl)amino.

[0104] In the above general formula (2), R 1 and R 2Specific examples of the group represented by the general formula (2) in the case of a trihydrocarbylsilyl group include amino groups containing a trialkylsilyl group, such as bis(trimethylsilyl)amino, bis(tert-butyldimethylsilyl)amino, and N-trimethylsilyl-N-methylamino.

[0105] In the above general formula (2), R 1 With R 2 Specific examples of the group represented by the general formula (2) above, when combined with each other to form an alkylene group, include 1-trimethyleneimino, 1-pyrrolidinyl, 1-piperidino, 1-hexamethyleneimino, 1-heptamethyleneimino, 1-octamethyleneimino, 1-decamethyleneimino, 1-dodecamethyleneimino and other 1-alkyleneimino groups.

[0106] In the above general formula (2), R 1 With R 2 Specific examples of the group represented by the general formula (2) when they are bonded to form a hydrocarbylene group containing a nitrogen atom and / or an oxygen atom include 1-imidazolyl, 4,5-dihydro-1-imidazolyl, and morpholino.

[0107] The group represented by the general formula (2) is preferably a dialkylamino group or a 1-alkyleneimino group, more preferably a dialkylamino group, and still more preferably a dimethylamino group, a diethylamino group, or a di-n-butylamino group.

[0108] In the above general formula (1), as the compound that can constitute X 2 、X 3 and X 4 Examples of the hydrocarbyloxy group include alkoxy groups such as methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, sec-butoxy, and tert-butoxy; and aryloxy groups such as phenoxy and benzyloxy.

[0109] In the above general formula (1), as the compound that can constitute X 2 、X 3 and X 4 Examples of the hydrocarbon group include alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, and tert-butyl; aryl groups such as phenyl, 4-methyl-1-phenyl, and benzyl; and the like.

[0110] In the ability to constitute X 2 、X 3 and X 4 When the hydrocarbyl group has a substituent, examples thereof include a hydrocarbyl group having a hydrocarbyloxy group as a substituent, and examples thereof include alkoxyalkyl groups such as methoxymethyl, ethoxymethyl, and ethoxyethyl.

[0111] In the above general formula (1), X 1 is a chemical single bond, X2 、X 3 and X 4 Specific examples of the vinyl compound containing a silicon atom-containing functional group represented by the general formula (1) above, in which one of the vinyl compounds is a substituted amino group, 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; and [bis(trimethylsilyl)amino]dimethylvinylsilane, [bis(tert-butyldimethylsilyl)amino]dimethylvinylsilane, [bis(trimethylsilyl)amino]diethylvinylsilane, and [bis(tert-butyldimethylsilyl)amino]diethylvinylsilane. [Bis(trialkylsilyl)amino]dialkylvinylsilane; (dimethylamino)bis(methoxymethyl)vinylsilane, (dimethylamino)bis(methoxyethyl)vinylsilane, (dimethylamino)bis(ethoxymethyl)vinylsilane, (dimethylamino)bis(ethoxyethyl)vinylsilane, (diethylamino)bis(methoxymethyl)vinylsilane, (diethylamino)bis(ethoxymethyl)vinylsilane, (diethylamino)bis(ethoxyethyl)vinylsilane, and the like (dialkylamino)bis(alkoxyalkyl)vinylsilanes; cyclic aminodialkylvinylsilane compounds such as pyrrolidinyldimethylvinylsilane, piperidinodimethylvinylsilane, hexamethyleneiminodimethylvinylsilane, 4,5-dihydroimidazolyldimethylvinylsilane, and morpholinodimethylvinylsilane; etc.

[0112] In the above general formula (1), X 1 is an alkylene group, X 2 、X 3 and X 4Specific examples of the vinyl compound containing a silicon atom-containing functional group represented by the general formula (1) above, in which one of the vinyl compounds is a substituted amino group, 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-4-vinylphenylsilane, (di-n-butylamino)dimethyl-3-vinylphenylsilane, (di-n-propylamino)dimethyl-4-vinylphenylsilane, (di-n-butylamino)dimethyl-3 ... (Dialkylamino)dialkylvinylphenylsilanes such as (dimethylamino)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)diethyl-3-vinylphenylsilane, (di-n-butylamino)diethyl-4-vinylphenylsilane, and (di-n-butylamino)diethyl-3-vinylphenylsilane.

[0113] In the above general formula (1), X 1 is a chemical single bond, X 2 、X 3 and X 4Specific examples of the vinyl compound containing a silicon atom-containing functional group represented by the general formula (1) above, in which two of the vinyl compounds are substituted amino groups, 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; and bis[bis(trimethylsilyl)amino]methylvinylsilane, bis[bis(tert-butyldimethylsilyl)amino]methylvinylsilane, bis[bis(trimethylsilyl)amino]ethylvinylsilane, bis[bis(tert-butyldimethylsilyl)amino]ethylvinylsilane. Bis(dialkylamino)alkoxyalkylsilanes such as bis(dimethylamino)methoxymethylvinylsilane, bis(dimethylamino)methoxyethylvinylsilane, bis(dimethylamino)ethoxymethylvinylsilane, bis(dimethylamino)ethoxyethylvinylsilane, bis(diethylamino)methoxymethylvinylsilane, bis(diethylamino)methoxyethylvinylsilane, bis(diethylamino)ethoxymethylvinylsilane, 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; etc.

[0114] In the above general formula (1), X 1 is an alkylene group, X 2 、X 3 and X 4Specific examples of the vinyl compound containing a silicon atom-containing functional group represented by the general formula (1) above, in which two of the vinyl compounds are substituted amino groups, 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-4-vinylphenylsilane, Bis(dialkylamino)alkylvinylphenylsilanes such as bis(dimethylamino)methyl-3-vinylphenylsilane, 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.

[0115] In the above general formula (1), X 1 is a chemical single bond, X 2 、X 3 and X 4 Specific examples of the vinyl compound containing a silicon atom-containing functional group represented by the general formula (1) above, in which three of the functional groups are substituted amino groups, include tris(dimethylamino)vinylsilane, tris(diethylamino)vinylsilane, tris(di-n-propylamino)vinylsilane, tris(di-n-butylamino)vinylsilane, and other tris(dialkylamino)vinylsilanes.

[0116] In the above general formula (1), X 1 is an alkylene group, X 2 、X 3 and X 4 Specific examples of the vinyl compound containing a silicon atom-containing functional group represented by the general formula (1) above, in which three of the vinyl compounds are substituted amino groups, include 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, tris(di-n-butylamino)-3-vinylphenylsilane and other tris(dialkylamino)vinylphenylsilanes.

[0117] In the above general formula (1), X 1 is a chemical single bond, X 2 、X 3 and X 4 Specific examples of the vinyl compound containing a silicon atom-containing functional group represented by the general formula (1) above, in which none of the compounds is a substituted amino group, include trialkoxyvinylsilanes such as trimethoxyvinylsilane, triethoxyvinylsilane, and tripropoxyvinylsilane; dialkoxyalkylvinylsilanes such as methyldimethoxyvinylsilane and methyldiethoxyvinylsilane; dialkoxyarylvinylsilanes such as di(tert-amyloxy)phenylvinylsilane and di(tert-butoxy)phenylvinylsilane; monoalkoxydialkylvinylsilanes such as dimethylmethoxyvinylsilane; monoalkoxydiarylvinylsilanes such as tert-butoxydiphenylvinylsilane and tert-amyloxydiphenylvinylsilane; monoalkoxyalkylarylvinylsilanes such as tert-butoxymethylphenylvinylsilane and tert-butoxyethylphenylvinylsilane; substituted alkoxyvinylsilane compounds such as tris(β-methoxyethoxy)vinylsilane; and the like.

[0118] Among the compounds represented by the above general formula (1), X 1 A compound having a chemical single bond, more preferably X 1 is a chemical single bond, and X 2 、X 3 and X 4 A compound wherein two of them are substituted amino groups, and X 1 is a chemical single bond, and X 2 、X 3 and X 4 A compound in which two of them are dialkylamino groups.

[0119] Among the compounds represented by the general formula (1), bis(dimethylamino)methylvinylsilane, bis(diethylamino)methylvinylsilane, and bis(di-n-butylamino)methylvinylsilane are preferred, and bis(diethylamino)methylvinylsilane is particularly preferred.

[0120] In addition, examples of vinyl compounds containing functional groups capable of interacting with silica other than the compound represented by the 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; and pyrrolidinylethylstyrene. Among them, pyrrolidinylethylstyrene is preferred. It should be noted that pyrrolidinylethylstyrene may be any of the ortho, meta, and para forms, but is preferably the meta or para form, and more preferably a mixture of the meta and para forms.

[0121] It should be noted that when the compound represented by the above-mentioned general formula (1) is used as the vinyl compound containing a functional group capable of interacting with silica, a unit represented by the following general formula (3) is introduced into the specific conjugated diene rubber as a unit of the vinyl compound containing a functional group capable of interacting with silica.

[0122]

[0123] In the above general formula (3), X 5 Represents a chemical single bond or alkylene group, X 6 、X 7 and X 8 Each independently represents a hydroxyl group, a substituted amino group, a hydrocarbyloxy group, or a hydrocarbyl group which may have a substituent.

[0124] It should be noted that in the unit represented by the general formula (3), X 5 X in the compound represented by the above general formula (1) 1 Correspondingly, in the unit represented by the above general formula (3), X 6 、X 7 and X 8 X in the compound represented by the above general formula (1) 2 、X 3 and X 4 Therefore, in the unit represented by the general formula (3), X 5 、X 6 、X 7 and X 8 Can be combined with X in the compound represented by the above general formula (1) 1 、X 2 、X 3 and X 4In addition, as the compound represented by the above general formula (1), when X 2 、X 3 and X 4 In the case of a compound in which at least one of the substituted amino groups or the alkyloxy group is a substituted amino group or the alkyloxy group, the substituted amino group or the alkyloxy group is hydrolyzed in an arbitrary step and at an arbitrary timing, thereby making X 2 、X 3 and X 4 At least one of them is a hydroxyl group.

[0125] <Content>

[0126] The content of units of the vinyl compound containing a functional group capable of interacting with silica in polymer block (A) is not particularly limited, but is preferably adjusted to preferably be in the range of 0.01 to 20% by mass, more preferably 0.02 to 2% by mass, and particularly 0.05 to 1% by mass, relative to the total monomer units constituting polymer block (A). By adjusting the content of units of the vinyl compound containing a functional group capable of interacting with silica within this range, the effects of suppressing adhesion to rollers, reducing heat buildup, and improving handling stability can be more pronounced.

[0127] <Other monomer units>

[0128] Furthermore, polymer block (A) may contain monomer units other than isoprene monomer units, aromatic vinyl monomer units, and units of vinyl compounds containing functional groups capable of interacting with silica. Examples of other compounds constituting such 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; and non-conjugated diene compounds such as 1,5-hexadiene, 1,6-heptadiene, 1,7-octadiene, dicyclopentadiene, and 5-ethylidene-2-norbornene. The content of these other monomer units in polymer block (A) is preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably 6% by mass or less.

[0129] [Weight average molecular weight (Mw)]

[0130] The weight-average molecular weight (Mw) of the polymer block (A) is in the range of 1,000 to 30,000, preferably in the range of 1,500 to 20,000, and more preferably in the range of 2,000 to 10,000. If the weight-average molecular weight (Mw) of the polymer block (A) is too low, the effect of suppressing adhesion to rollers, and the effects of improving low heat buildup and handling stability are not achieved. On the other hand, if the weight-average molecular weight (Mw) of the polymer block (A) is too high, the low heat buildup properties of the resulting rubber cross-linked product are reduced.

[0131] 〔Mw / Mn〕

[0132] Furthermore, 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 polymer block (A) is preferably 1.0 to 1.5, more preferably 1.0 to 1.3. When the molecular weight distribution (Mw / Mn) of the polymer block (A) is within this range, the production of the conjugated diene rubber becomes easier.

[0133] In addition, in this specification, the weight average molecular weight (Mw) and the number average molecular weight (Mn) can be determined as polystyrene-equivalent values ​​by gel permeation chromatography (GPC) measurement.

[0134] [Polymer block (B)]

[0135] The polymer block (B) is not particularly limited as long as it contains 1,3-butadiene monomer units (preferably containing 1,3-butadiene monomer units as the main component). It may be composed solely of 1,3-butadiene monomer units or may be composed of 1,3-butadiene monomer units and monomer units other than 1,3-butadiene monomer units. In this case, the monomer units other than 1,3-butadiene monomer units are preferably aromatic vinyl monomer units. The polymer block (B) of the present invention preferably contains aromatic vinyl monomer units in addition to 1,3-butadiene monomer units.

[0136] 〔1,3-Butadiene monomer unit content〕

[0137] The content of 1,3-butadiene monomer units in polymer block (B) (1,3-butadiene monomer unit content) is preferably 55 to 65% by mass, more preferably 55 to 63% by mass, and even more preferably 55 to 60% by mass. By adjusting the 1,3-butadiene monomer unit content in polymer block (B) to be within this range, the production of the conjugated diene rubber is facilitated.

[0138] [Vinyl bond content in 1,3-butadiene monomer units]

[0139] The vinyl bond content of the 1,3-butadiene monomer units in the polymer block (B) is preferably 10 to 50% by mass, more preferably 15 to 40% by mass, and particularly preferably 20 to 35% by mass. By adjusting the vinyl bond content of the 1,3-butadiene monomer units in the polymer block (B) within this range, the resulting cross-linked rubber can exhibit even better low heat buildup properties.

[0140] [Aromatic vinyl compound for forming aromatic vinyl monomer units]

[0141] As the aromatic vinyl compound used to form the aromatic vinyl monomer units, the compounds exemplified in the description of the polymer block (A) can be used. Among the aromatic vinyl compounds described above, styrene is preferred. The aromatic vinyl monomer unit content of the polymer block (B) is preferably 35 to 45% by mass, more preferably 40 to 45% by mass.

[0142] [Units of a vinyl compound containing a functional group capable of interacting with silica]

[0143] In addition, the specific conjugated diene rubber contains units of a vinyl compound containing a functional group capable of interacting with silica in at least one of the polymer block (A) and the polymer block (B). However, in the specific conjugated diene rubber, such units of a vinyl compound containing a functional group capable of interacting with silica may be contained only in the polymer block (A), only in the polymer block (B), or in both the polymer block (A) and the polymer block (B). For reasons of achieving superior effects of the present invention, it is preferred that at least the polymer block (B) of the specific conjugated diene rubber contain units of a vinyl compound containing a functional group capable of interacting with silica.

[0144] <Vinyl compounds containing functional groups capable of interacting with silica>

[0145] As the vinyl compound containing a functional group capable of interacting with silica, which is used to form the unit of the vinyl compound containing 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 compounds exemplified as preferred compounds in the description of the above polymer block (A) can be suitably used.

[0146] <Content>

[0147] The content of the vinyl compound unit containing a functional group capable of interacting with silica in the polymer block (B) is not particularly limited, but is preferably adjusted to preferably be in the range of 0.01 to 20% by mass, more preferably in the range of 0.02 to 2% by mass, and particularly in the range of 0.05 to 1% by mass, relative to the total monomer units constituting the polymer block (B).

[0148] <Other monomer units>

[0149] In addition, polymer block (B) may also contain other monomer units other than 1,3-butadiene monomer units, aromatic vinyl monomer units, and units of vinyl compounds containing functional groups capable of interacting with silica. As other compounds constituting such other monomer units, in addition to the same compounds as those exemplified in the above-mentioned polymer block (A) (excluding 1,3-butadiene), isoprene may also be used. The content of other monomer units in polymer block (B) is preferably 40% by mass or less, more preferably 35% by mass or less, and even more preferably 25% by mass or less.

[0150] [Mass ratio of polymer block (A) to polymer block (B)]

[0151] The mass ratio of the polymer block (A) to the polymer block (B) in the specific conjugated diene rubber (when a plurality of polymer blocks (A) and (B) are present, the mass ratio based on the total mass of each) is preferably 0.001 to 0.2, more preferably 0.005 to 0.1, and particularly preferably 0.01 to 0.05, calculated as (mass of polymer block (A)) / (mass of polymer block (B)). By keeping the mass ratio of the polymer block (A) to the polymer block (B) within this range, the resulting cross-linked rubber can be well balanced in wet grip properties and low heat buildup properties.

[0152] [Content of each unit]

[0153] 〔1,3-Butadiene monomer unit content〕

[0154] The content of 1,3-butadiene monomer units in the entire specific conjugated diene rubber (1,3-butadiene monomer unit content) is not particularly limited, but is preferably 55 to 65% by mass, more preferably 55 to 63% by mass, and even more preferably 55 to 60% by mass, for reasons of achieving superior effects of the present invention. The 1,3-butadiene monomer unit content in the entire specific conjugated diene rubber herein refers to the content of 1,3-butadiene monomer units relative to all monomer units constituting the specific conjugated diene rubber.

[0155] [Aromatic vinyl monomer unit content]

[0156] As described above, the content of aromatic vinyl monomer units in the specific conjugated diene rubber as a whole (aromatic vinyl monomer unit content) is 30 to 45% by mass. Here, the aromatic vinyl monomer unit content in the specific conjugated diene rubber as a whole refers to the content of aromatic vinyl monomer units relative to all monomer units constituting the specific conjugated diene rubber.

[0157] Since the effects of the present invention are more excellent, the aromatic vinyl monomer unit content of the entire specific conjugated diene rubber is preferably 35 to 45% by mass, more preferably 40 to 45% by mass.

[0158] [Content of units of vinyl compounds containing functional groups capable of interacting with silica]

[0159] The content of the units of the vinyl compound containing a functional group capable of interacting with silica (for example, the content of bis(diethylamino)methylvinylsilane monomer units) in the specific conjugated diene rubber as a whole is not particularly limited, but is preferably 0.01 to 20% by mass, more preferably 0.02 to 2% by mass, and even more preferably 0.05 to 1% by mass, for the reason that the effects of the present invention are more excellent.

[0160] [Vinyl bond content]

[0161] The vinyl bond content of the conjugated diene monomer units (e.g., isoprene monomer units and 1,3-butadiene monomer units) in the specific conjugated diene rubber as a whole (hereinafter referred to as the "vinyl bond content of the specific conjugated diene rubber as a whole") is 15 to 35% by mass. For reasons of achieving even greater effects of the present invention, the vinyl bond content is preferably 20 to 25% by mass, and more preferably 25 to 35% by mass. By setting the vinyl bond content of the specific conjugated diene rubber as a whole within this range, the resulting cross-linked rubber can be further improved in low heat buildup properties.

[0162] [Modified structure formed by siloxane compound]

[0163] As described above, the specific conjugated diene rubber has a modified structure formed by a siloxane compound at at least one terminal. Note that the modified structure formed by a siloxane compound may also be introduced via a modified structure formed by another modifier.

[0164] Suitable solution

[0165] 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).

[0166]

[0167] In the above general formula (4), R 3 ~R 10 is an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, which may be the same as or different from each other. 9 and X 12 It is any group selected from 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 an epoxy group-containing group having 4 to 12 carbon atoms, and these groups may be the same or different. 10 is an alkoxy group having 1 to 5 carbon atoms, or a group having 4 to 12 carbon atoms containing an epoxy group, wherein X 10 When there are multiple, they can be the same or different. 11 A group containing 2 to 20 repeating units of alkylene glycol, wherein X 11 When there are multiple groups, 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.

[0168] In the polyorganosiloxane represented by the general formula (4), as a constituent of R 3 ~R 10 、X 9 and X 12 Examples of the alkyl group having 1 to 6 carbon atoms include methyl, ethyl, n-propyl, isopropyl, butyl, pentyl, hexyl, and cyclohexyl. Examples of the aryl group having 6 to 12 carbon atoms include phenyl and methylphenyl. Among these, methyl and ethyl are preferred from the perspective of ease of production of the polyorganosiloxane itself.

[0169] In the polyorganosiloxane represented by the general formula (4), as a compound capable of constituting X 9 、X 10 and X 12 Examples of the alkoxy group having 1 to 5 carbon atoms include methoxy, ethoxy, propoxy, isopropoxy, and butoxy. Among these, methoxy and ethoxy are preferred from the viewpoint of ease of production of the polyorganosiloxane itself.

[0170] Furthermore, in the polyorganosiloxane represented by the general formula (4), as a compound capable of constituting X 9 、X 10 and X 12 The group having 4 to 12 carbon atoms containing an epoxy group includes, for example, a group represented by the following general formula (5).

[0171] -Z 1 -Z 2 -E(5)

[0172] In the above general formula (5), Z 1 is an alkylene group or an alkylarylene group having 1 to 10 carbon atoms, Z 2 is a methylene group, a sulfur atom, or an oxygen atom, and E is a hydrocarbon group having 2 to 10 carbon atoms and having an epoxy group.

[0173] As the group represented by the general formula (5), Z is preferably 2 is an oxygen atom, more preferably Z 2 is an oxygen atom, and E is a glycidyl group, and Z is particularly preferred 1 is an alkylene group having 1 to 3 carbon atoms, Z 2 is an oxygen atom, and E is a glycidyl group.

[0174] In the polyorganosiloxane represented by the general formula (4), X 9 and X 12 Among the above, a group having 4 to 12 carbon atoms or an alkyl group having 1 to 6 carbon atoms containing an epoxy group is preferred. 10 Among the above, a group having 4 to 12 carbon atoms and containing an epoxy group is preferred. Furthermore, X is more preferably 9 and X 12 is an alkyl group with 1 to 6 carbon atoms, X 10 It is a group having 4 to 12 carbon atoms and containing an epoxy group.

[0175] In the polyorganosiloxane represented by the general formula (4), X 11 , that is, a group containing 2 to 20 repeating units of an alkylene glycol, preferably a group represented by the following general formula (6).

[0176]

[0177] In the above general formula (6), t is an integer from 2 to 20, and X 13 is an alkylene group or an alkylarylene group having 2 to 10 carbon atoms, R 11 is a hydrogen atom or a methyl group, X 14 is an alkoxy group or an aryloxy group having 1 to 10 carbon atoms. Among them, t is preferably an integer of 2 to 8, and X 13 is an alkylene group with 3 carbon atoms, R 11 is a hydrogen atom, and X 14 A methoxy group.

[0178] In the polyorganosiloxane represented by the 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 represented by the general formula (4) itself can be produced more easily, and its viscosity does not become too high, making it easier to handle.

[0179] In the polyorganosiloxane represented by the 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 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 of m, n, and k is 1 or more, the reaction between the polyorganosiloxane represented by the general formula (4) and the conjugated diene polymer chain having an active terminal proceeds easily. Furthermore, when the total of m, n, and k is 400 or less, the polyorganosiloxane represented by the general formula (4) itself can be easily produced, and its viscosity does not become too high, making it easy to handle.

[0180] [Weight average molecular weight (Mw)]

[0181] The weight-average molecular weight (Mw) of the specific conjugated diene rubber as a whole is in the range of 50,000 to 5,000,000, preferably in the range of 75,000 to 3,000,000, and more preferably in the range of 100,000 to 1,000,000. By setting the weight-average molecular weight of the specific conjugated diene rubber as a whole within this range, the incorporation of silica into a rubber composition containing such a conjugated diene rubber is facilitated, the processability of the rubber composition can be further improved, and the low heat build-up properties of the resulting cross-linked rubber can be further enhanced.

[0182] [Mw / Mn]

[0183] Furthermore, the overall molecular weight distribution of the specific conjugated diene rubber, represented 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. By keeping the molecular weight distribution (Mw / Mn) within this range, the low heat buildup properties of the resulting cross-linked rubber can be further improved.

[0184] [Mooney viscosity]

[0185] In addition, the Mooney viscosity (ML) of the specific conjugated diene rubber 1+4, 100°C) is preferably 20 to 100, more preferably 30 to 90, 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.

[0186] [Glass transition temperature (Tg)]

[0187] The glass transition temperature (Tg) of the specific conjugated diene rubber is not particularly limited, but is preferably 20 to -110° C., more preferably 10 to -70° C. The glass transition temperature of the specific conjugated diene rubber can be appropriately adjusted, for example, by adjusting the content of aromatic vinyl monomer units in the conjugated diene rubber and the content of vinyl bonds in the conjugated diene monomer units.

[0188] [Manufacturing method]

[0189] The specific conjugated diene rubber 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 terminal (step A);

[0190] a step of mixing the obtained polymer block (A) having an active terminal with a monomer (b) containing 1,3-butadiene and continuing the polymerization reaction to obtain a conjugated diene polymer chain having an active terminal and comprising the polymer block (A) and the polymer block (B) (step B); and

[0191] A step of reacting the siloxane compound with the active terminal of the obtained conjugated diene polymer chain having an active terminal (step C).

[0192] [Step of forming a polymer block (A) having an active terminal (Step A)]

[0193] <Single substance (a)>

[0194] The monomer (a) used to form the polymer block (A) may contain isoprene, and any monomer corresponding to the monomer composition (the above-mentioned monomer composition) of the polymer block (A) to be formed may be used. For example, when the polymer block (A) is composed of isoprene monomer units and aromatic vinyl monomer units, the monomer (a) may contain isoprene and an aromatic vinyl compound. Furthermore, when the polymer block (A) contains units of a vinyl compound containing a functional group capable of interacting with silica in addition to the isoprene monomer units and the aromatic vinyl monomer units, the monomer (a) may contain a vinyl compound containing a functional group capable of interacting with silica in addition to the isoprene monomer units and the aromatic vinyl compound.

[0195] <Inactive solvent>

[0196] In order to form the polymer block (A), the inert solvent used for the polymerization of the monomer (a) containing isoprene is a substance commonly 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 chain or branched aliphatic hydrocarbons such as propane, n-butane, isobutane, n-pentane, isopentane, n-hexane, propylene, 1-butene, isobutylene, 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; and the like. These inert solvents may be used alone or in combination of two or more. The amount of the inert solvent used is not particularly limited, but is an amount such that the monomer concentration is, for example, 1 to 80% by mass, preferably 5 to 50% by mass.

[0197] <Polymerization initiator>

[0198] The polymerization initiator used to form the polymer block (A) is not particularly limited as long as it can polymerize the monomer (a) containing isoprene to obtain a polymer chain having an active terminal. Specific examples thereof include polymerization initiators using organic alkali metal compounds, organic alkaline earth metal compounds, and lanthanum-based metal compounds as main catalysts. Examples of the organic alkali metal compound include n-butyllithium, sec-butyllithium, tert-butyllithium, hexyllithium, phenyllithium, ethyllithium, n-propyllithium, isopropyllithium, tert-octyllithium, n-decyllithium, 2-naphthyllithium, 2-butylphenyllithium, 4-phenylbutyllithium, hexyllithium, cyclopentyllithium, a reaction product of diisopropenylbenzene and butyllithium, and stilbene lithium; organic polyvalent lithium compounds such as dilithium methane, 1,4-dilithium butane, 1,4-dilithium-2-ethylcyclohexane, 1,3,5-trilithium benzene, 1,3,5-tris(lithiummethyl)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 naphthyl; organic potassium compounds such as potassium naphthalene; organic rubidium compounds; and organic cesium compounds. In addition, examples include alkoxides, sulfonates, carbonates, and amides of lithium, sodium, and potassium. Furthermore, other organometallic compounds may be used in combination. Furthermore, known organic alkali metal compounds disclosed in U.S. Patent No. 5,708,092, British Patent No. 2,241,239, and U.S. Patent No. 5,527,753 may also be used.

[0199] Examples of organic alkaline earth metal compounds include di-n-butyl magnesium, di-n-hexyl magnesium, calcium diethoxide, calcium distearate, di-tert-butoxystrontium, barium diethoxide, barium diisopropoxide, barium diethylmercaptobarium, di-tert-butoxybarium, barium diphenoxide, barium diethylamino, barium distearate, and barium dicarbonyl. Examples of polymerization initiators using a lanthanum-based metal compound as a main catalyst include a lanthanum-based metal salt composed of lanthanum, cerium, praseodymium, neodymium, samarium, or gadolinium, carboxylic acid, or a phosphorus-containing organic acid, and a co-catalyst such as an alkylaluminum compound, an organoaluminum hydride compound, or an organoaluminum halide compound. Among these polymerization initiators, organic monolithium compounds and organic multivalent lithium compounds are preferred, and organic monolithium compounds are more preferred. n-butyllithium is particularly preferred from the perspectives of industrial availability and ease of control of the polymerization reaction. It should be noted that, can make in advance organic alkali metal compound and secondary amine reaction such as dibutylamine, dihexylamine, dibenzylamine, pyrrolidines, piperidines, hexamethyleneimine and heptamethyleneimine and use as organic alkali metal amide compound.These polymerization initiators can use 1 kind alone, also can use 2 or more kinds in combination.As this organic alkali metal amide compound, it is not particularly limited, for example can enumerate, lithium hexamethyleneimine, lithium pyrrolidide, lithium piperidinide, lithium heptamethyleneimine, lithium dodecamethyleneimine, lithium dimethylamide, lithium diethylamide, lithium dibutylamide, lithium dipropylamide, lithium diheptylamide, lithium dihexylamide, lithium dioctylamide, lithium di-2-ethylhexylamide, lithium didecylamide, N-methylpiperazine lithium, lithium ethylpropylamide, lithium ethylbutylamide, lithium ethylbenzylamide and lithium methyl phenethylamide etc.

[0200] (Amount used)

[0201] The amount of the polymerization initiator used may be determined according to the target molecular weight, but is preferably 4 to 250 mmol, more preferably 6 to 200 mmol, and particularly preferably 10 to 70 mmol per 100 g of the monomer (a) containing isoprene.

[0202] <Polymerization Temperature when Polymerizing Monomer (a)>

[0203] The polymerization temperature when polymerizing the monomer (a) containing isoprene is preferably -80 to +150°C, more preferably 0 to 100°C, and even more preferably 20 to 90°C. The polymerization method may be either a batch method or a continuous method. Furthermore, when the polymer block (A) is a copolymer chain, various bonding methods may be used, such as block, tapered, and random bonding methods.

[0204] Polar compounds

[0205] Furthermore, when polymerizing monomer (a), in order to adjust the vinyl bond content in the isoprene monomer units in the polymer block (A), it is preferred to add a polar compound to an inert solvent during polymerization. Examples of polar compounds include ether compounds such as dibutyl ether, tetrahydrofuran, and 2,2-di(tetrahydrofuryl)propane; tertiary amines such as tetramethylethylenediamine; alkali metal alkoxides; phosphine compounds; and the like. Of these, ether compounds and tertiary amines are preferred, tertiary amines are more preferred, and tetramethylethylenediamine is particularly preferred. These polar compounds may be used alone or in combination of two or more. The amount of the polar compound used can be determined based on the target vinyl bond content and is preferably 0.01 to 30 moles, more preferably 0.05 to 10 moles, relative to 1 mole of the polymerization initiator. If the amount of the polar compound used is within the above range, the vinyl bond content in the isoprene monomer units can be easily adjusted, and problems caused by deactivation of the polymerization initiator are less likely to occur. Furthermore, 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.

[0206] [Step of Obtaining a Conjugated Diene Polymer Chain Having an Active Terminal (Step B)]

[0207] Next, a polymer block (A) having an active terminal obtained by polymerizing a monomer (a) containing isoprene and a monomer (b) containing 1,3-butadiene are mixed and the polymerization reaction is continued. This allows polymer block (B) to be formed continuously with polymer block (A), thereby obtaining a conjugated diene polymer chain having an active terminal, including polymer block (A) and polymer block (B). It should be noted that the formed polymer block (B) has an active terminal, while the active terminal disappears from polymer block (A).

[0208] <Single substance (b)>

[0209] The monomer (b) used to form the polymer block (B) only needs to contain 1,3-butadiene, and any monomer that corresponds to the monomer composition (the above-mentioned monomer composition) of the polymer block (B) to be formed can be used. For example, when the polymer block (B) is composed of 1,3-butadiene monomer units and aromatic vinyl monomer units, the monomer (b) only needs to contain 1,3-butadiene and an aromatic vinyl compound. In addition, when the polymer block (B) further contains units of a vinyl compound containing a functional group capable of interacting with silica in addition to the 1,3-butadiene monomer units and the aromatic vinyl monomer units, the monomer (b) only needs to contain a vinyl compound containing a functional group capable of interacting with silica in addition to the 1,3-butadiene monomer units and the aromatic vinyl compound.

[0210] (Vinyl compound containing a functional group capable of interacting with silica)

[0211] It should be noted that the specific conjugated diene rubber contains units of a vinyl compound containing a functional group capable of interacting with silica in at least one of the polymer block (A) and the polymer block (B). Therefore, in the above-mentioned production method, it is sufficient that at least one of the monomer (a) containing isoprene used to form the polymer block (A) and the monomer (b) containing 1,3-butadiene used to form the polymer block (B) contains a vinyl compound containing a functional group capable of interacting with silica.

[0212] <Inactive solvent>

[0213] The inert solvent used for polymerization of the monomer (b) containing 1,3-butadiene to form the polymer block (B) is not particularly limited, and the same inert solvents as those described above can be used.

[0214] <Used amount of polymer block (A) having an active terminal>

[0215] The amount of the polymer block (A) having an active terminal used to form the polymer block (B) can be determined according to the target molecular weight, but is preferably in the range of 0.1 to 5 mmol, more preferably 0.15 to 2 mmol, and even more preferably 0.2 to 1.5 mmol per 100 g of the monomer (b) containing 1,3-butadiene.

[0216] <Method of Mixing the Polymer Block (A) and the Monomer (b) Containing 1,3-Butadiene>

[0217] The method for mixing the polymer block (A) and the monomer (b) containing 1,3-butadiene is not particularly limited. The polymer block (A) having an active terminal 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 an active terminal. From the viewpoint of controlling polymerization, the method of adding the polymer block (A) having an active terminal to a solution of the monomer (b) containing 1,3-butadiene is preferred.

[0218] <Polymerization temperature, polymerization method>

[0219] The polymerization temperature when polymerizing the monomer (b) containing 1,3-butadiene is preferably -80 to +150°C, more preferably 0 to 100°C, and even more preferably 20 to 90°C. The polymerization method can be either batch or continuous. When the polymer block (B) is a copolymer chain, a batch method is preferred because it is easier to control the randomness of the bonding.

[0220] <Combination method>

[0221] When the polymer block (B) is a copolymer chain, the monomers may be bonded in various ways, such as block, tapered, and random. Among these, random bonding is preferred. A random bonding further improves the low heat buildup properties of the resulting cross-linked rubber.

[0222] Polar compounds

[0223] In addition, in order to adjust the vinyl bond content in the 1,3-butadiene monomer unit in the polymer block (B), it is preferred to add a polar compound to an inert solvent during polymerization, similarly to the adjustment of the vinyl bond content in the isoprene monomer unit in the polymer block (A). However, when a sufficient amount of polar compound is added to the inert solvent to adjust the vinyl bond content in the 1,3-butadiene monomer unit in the polymer block (B) during the preparation of the polymer block (A), it is not necessary to newly add a polar compound. As the polar compound used to adjust the vinyl bond content, the same substances as the above-mentioned polar compounds can be used. The amount of the polar compound used can be determined according to the target vinyl bond content, and it can be adjusted in the range of preferably 0.01 to 100 moles, more preferably 0.1 to 30 moles, relative to 1 mole of the polymerization initiator used in the initial polymerization reaction (polymerization reaction for forming the first 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 problems due to deactivation of the polymerization initiator are less likely to occur.

[0224] <Conjugated diene polymer chain with active terminal>

[0225] Such operation can obtain a conjugated diene polymer chain with polymer block (A) and polymer block (B), with active end. In the present invention, from the viewpoint of productivity, the conjugated diene polymer chain preferably with active end is composed of polymer block (A)-polymer block (B), and the end of polymer block (B) is an active end, but it is also possible to have multiple polymer blocks (A), it is also possible to have other polymer blocks. For example, polymer block (A)-polymer block (B)-polymer block (A) etc. can be cited as having a conjugated diene polymer chain with active end. In this case, the end of the polymer block (A) formed after polymer block (B) forms an active end. When the polymer block (A) forms the active terminal side of the conjugated diene polymer chain, the amount of isoprene used is preferably 10 to 100 mol, more preferably 15 to 70 mol, and particularly preferably 20 to 35 mol, relative to 1 mol of the polymerization initiator used in the initial polymerization reaction (polymerization reaction for forming the first polymer block (A)).

[0226] [Step of reacting a siloxane compound with an active terminal of a conjugated diene polymer chain having an active terminal (Step C)]

[0227] Next, a siloxane compound is reacted with the active terminal of the obtained conjugated diene polymer chain having an active terminal, thereby introducing a modified structure formed by the siloxane compound into the terminal of the conjugated diene polymer chain.

[0228] <Usage amount of silicone compound>

[0229] When reacting a conjugated diene polymer chain having an active terminal with a siloxane compound, the amount of the siloxane compound used is preferably 0.01 to 10 mol, and more preferably 0.1 to 5 mol, per 1 mol of the polymerization initiator used in the initial polymerization reaction (the polymerization reaction for forming the first polymer block (A)). When the amount of the siloxane compound used is within this range, the low heat buildup properties of the resulting cross-linked rubber can be further improved. The molar number per siloxane structure (-Si-O-) is preferably within the above range.

[0230] <Method for reacting a siloxane compound with a conjugated diene polymer chain having an active terminal>

[0231] There is no particular limitation on the method for reacting the siloxane compound with the conjugated diene polymer chain having an active end, and examples include a method of mixing them in a solvent in which each can be dissolved. As the solvent used at this time, the substances exemplified as the inert solvent used in the above-mentioned polymerization reaction can be used. In addition, at this time, the method of adding the siloxane compound to the polymerization solution used for the polymerization to obtain the conjugated diene polymer chain having an active end is simple and preferred. Furthermore, at this time, the siloxane compound is preferably dissolved in an inert solvent and added to the polymerization system, and the solution concentration is preferably in the range of 1 to 50% by mass. The reaction temperature is not particularly limited, but is usually 0 to 120°C. The reaction time is also not particularly limited, but is usually 1 minute to 1 hour.

[0232] <When to add silicone compounds>

[0233] The time for adding the siloxane compound to the solution containing the conjugated diene polymer chains with active ends is not particularly limited, but it is desirable that the siloxane compound be added to the solution before the polymerization reaction is completed and the solution containing the conjugated diene polymer chains with active ends also contains monomers. More specifically, the siloxane compound is added to the solution when the solution containing the conjugated diene polymer chains with active ends contains 100 ppm or more, more preferably 300 to 50,000 ppm of monomers. By adding the siloxane compound in this way, side reactions between the conjugated diene polymer chains with active ends and impurities contained in the polymerization system can be suppressed, and the reaction can be well controlled. It should be noted that in order to further improve the processability of the resulting rubber composition, the siloxane compound can be added to the solution containing the conjugated diene polymer chains with active ends, and after the reaction, an organometallic compound can be further mixed. This can improve the processability of the resulting rubber composition (the Mooney value of the rubber compound can be suppressed to a low level). In addition, in this case, the siloxane compound can be further added after the organometallic compound is mixed to further react. 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-butylphenyllithium, 4-phenylbutyllithium, hexyllithium, cyclopentyllithium, the reaction product of diisopropenylbenzene and butyllithium, and organic monolithium compounds such as stilbene lithium.

[0234] By reacting the siloxane compound with the active end of the conjugated diene polymer chain having an active end in this manner, a modified structure formed by the siloxane compound can be introduced into at least one end of the conjugated diene polymer chain. The conjugated diene polymer chain after the reaction has a modified structure formed by the siloxane compound introduced into the polymer chain end, but may also contain an unmodified conjugated diene polymer chain that has not been modified by the siloxane compound.

[0235] It should be noted that, as a conjugated diene polymer chain having an active terminal, by using a substance having an active terminal at the end of polymer block (A) (e.g., a polymer chain represented by polymer block (A)-polymer block (B)-polymer block (A)), and reacting a siloxane compound with the terminal of polymer block (A), a modified structure formed by the siloxane compound can be introduced at the terminal of polymer block (A). Alternatively, by using a substance having an active terminal at the end of polymer block (B) (e.g., a polymer chain represented by polymer block (A)-polymer block (B)), and reacting a siloxane compound with the terminal of polymer block (B), a modified structure formed by the siloxane compound can be introduced at the terminal of polymer block (B). From the viewpoint of further improving the low heat buildup properties of the resulting rubber cross-linked product, it is preferred to introduce a modified structure formed by the siloxane compound at the terminal of polymer block (B) by reacting a siloxane compound with the terminal of polymer block (B).

[0236] 〔Coupling〕

[0237] Furthermore, before reacting the siloxane compound with the conjugated diene polymer chain having an active terminal, or after reacting the siloxane compound with the conjugated diene polymer chain having an active terminal, when the conjugated diene polymer chain having an active terminal remains, a conventionally used coupling agent or the like may be added to the polymerization system to couple a portion of the active terminals of the conjugated diene polymer chain having an active terminal, within a range that does not impair the effects of the present invention.

[0238] 〔Inactivation〕

[0239] Furthermore, after the siloxane compound is reacted with the conjugated diene polymer chain having active terminals, a polymerization inhibitor such as an alcohol such as methanol, ethanol, or isopropyl alcohol, or water is preferably added to deactivate the unreacted active terminals.

[0240] 〔additive〕

[0241] After deactivating the active end of the conjugated diene polymer chain, in a solution of a conjugated diene rubber having a modified structure formed by a siloxane compound at the end, as needed, antioxidants such as phenolic stabilizers, phosphorus stabilizers, and sulfur stabilizers, crumb reagents, and anti-fouling agents are added to the reaction solution. Then, the polymerization solvent is separated from the reaction solution by direct drying or stripping, and the solid conjugated diene rubber having a modified structure formed by a siloxane compound at the end is recovered. Further, as needed, an extender oil can also be mixed to make the conjugated diene rubber an oil-extended rubber. As extender oils, for example, paraffin-based, aromatic-based, and cycloparaffin-based petroleum softeners, plant-based softeners, and fatty acids can be cited. When using a petroleum softener, the content of polycyclic aromatics extracted preferably by the IP346 method (the inspection method of THEINSTITUTE PETROLEUM in the UK) is less than 3%. When an extender oil is used, the amount used is usually 5 to 100 parts by mass based on 100 parts by mass of the conjugated diene rubber.

[0242] [content]

[0243] As described above, the content of the specific conjugated diene rubber in the rubber component is 35% by mass or more, preferably 40 to 85% by mass, and more preferably 45 to 80% by mass, for the purpose of achieving more excellent effects of the present invention.

[0244] [2]Specific butadiene rubber

[0245] As described above, the rubber component contains the specific butadiene rubber.

[0246] The specific butadiene rubber is a butadiene rubber having a glass transition temperature of -85°C or lower.

[0247] [Glass transition temperature (Tg)]

[0248] As described above, the glass transition temperature (Tg) of the specific butadiene rubber is -85°C or lower.

[0249] The Tg is preferably -90°C or lower for the purpose of achieving more excellent effects of the present invention. The lower limit of the Tg is not particularly limited, but is preferably -150°C or higher, more preferably -120°C or higher for the purpose of achieving more excellent effects of the present invention.

[0250] In this specification, the glass transition temperature (Tg) is measured using a differential scanning calorimeter (DSC) at a temperature increase rate of 10° C. / min and calculated by a midpoint method.

[0251] [Molecular weight]

[0252] The weight average molecular weight (Mw) of the specific butadiene rubber is not particularly limited, but is preferably 50,000 to 5,000,000, more preferably 75,000 to 3,000,000, and even more preferably 100,000 to 1,000,000 because the effects of the present invention are more excellent.

[0253] [Suitable solution]

[0254] Because the effects of the present invention are more excellent, the specific butadiene rubber is preferably a modified butadiene rubber, more preferably a modified butadiene rubber having a modifying group containing a heteroatom at at least one terminal. The modifying group is not particularly limited, and examples thereof include a hydroxyl group, an epoxy group, a carboxyl group, and a hydrocarbyloxysilyl group. The modifying group may be located in the main chain (side chain) or at a terminal.

[0255] In addition, the microstructure (cis-1,4-bond, trans-1,4-bond, vinyl bond) of the specific butadiene rubber is not particularly limited.

[0256] 〔Specific modified butadiene rubber〕

[0257] As a preferred embodiment of the specific butadiene rubber, a modified butadiene rubber having a modifying group containing a heteroatom at at least one terminal is preferred for the reasons of achieving superior effects of the present invention. Examples include modified butadiene polymers (specific modified butadiene rubbers) in which the active terminals of a butadiene polymer having a cis-1,4-bond content of 75 mol% or greater are modified with a hydrocarbyloxysilane compound. Examples of such specific modified butadiene rubbers include those described in paragraphs

[0017] to

[0023] of International Publication No. 2018 / 135530, the contents of which are incorporated herein by reference.

[0258] [content]

[0259] As described above, the content of the specific butadiene rubber in the rubber component is 15% by mass or greater. However, for the reason that the effects of the present invention are more excellent, it is preferably 20% by mass or greater. For the reason that the effects of the present invention are more excellent, the upper limit of the content of the specific butadiene rubber in the rubber component is preferably 65% ​​by mass or less, more preferably 50% by mass or less, and even more preferably 30% by mass or less.

[0260] [3] Amount ratio of specific conjugated diene rubber to specific butadiene rubber

[0261] Because the effects of the present invention are more excellent, the ratio of the content of the above-mentioned specific butadiene rubber to the content of the above-mentioned specific conjugated diene rubber in the rubber component (specific butadiene rubber / specific conjugated diene rubber) is preferably 10 to 60% by mass, more preferably 20 to 50% by mass, and even more preferably 30 to 40% by mass.

[0262] [4] Other rubber components

[0263] The rubber component may contain a rubber component (other rubber component) that does not correspond to any of the specific conjugated diene rubber and the specific butadiene rubber.

[0264] Examples of such other rubber components include natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR) other than the above-mentioned specific butadiene rubber, styrene-butadiene rubber (SBR) other than the above-mentioned specific conjugated diene rubber, acrylonitrile-butadiene copolymer rubber (NBR), butyl rubber (IIR), halogenated butyl rubber (Br-IIR, Cl-IIR), and chloroprene rubber (CR). Among these, styrene-butadiene rubber (SBR) other than the above-mentioned specific conjugated diene rubber is preferred because the effects of the present invention are more excellent.

[0265] [Molecular weight]

[0266] The weight average molecular weight (Mw) of the other rubber components is not particularly limited, but is preferably 50,000 to 5,000,000, more preferably 75,000 to 3,000,000, and even more preferably 100,000 to 1,000,000 because the effects of the present invention are more excellent.

[0267] [content]

[0268] The content of other rubber components in the rubber component is not particularly limited, but is preferably 0 to 50% by mass, more preferably 10 to 40% by mass, and even more preferably 20 to 30% by mass because the effects of the present invention are more excellent.

[0269] [II] Silica

[0270] The silica contained in the composition of the present invention is not particularly limited, and any conventionally known silica that is compounded in rubber compositions for applications such as tires can be used.

[0271] Specific examples of silica include wet silica, dry silica, fumed silica, and diatomaceous earth. Wet silica is preferred because it provides a more effective method for the present invention. The silica may be prepared using one type alone or in combination of two or more types.

[0272] [1] Content

[0273] In the composition of the present invention, the content of silica is 50 to 150 parts by mass per 100 parts by mass of the rubber component, and preferably 60 to 100 parts by mass because the effects of the present invention are more excellent.

[0274] [2] Suitable solutions

[0275] For the reason that the effect of the present invention is more excellent, the silica preferably contains CTAB (cetyltrimethylammonium bromide) with an adsorption specific surface area of ​​190 m 2 Of these, 50 to 150 parts by mass of the specific silica is preferably contained, and 60 to 100 parts by mass of the specific silica is more preferably contained, because the effects of the present invention are more excellent.

[0276] The upper limit of the CTAB adsorption specific surface area of ​​the specific silica is not particularly limited, but is preferably 300 m 2 / g or less.

[0277] Here, the CTAB adsorption specific surface area is a value obtained by measuring the amount of CTAB adsorbed on the silica surface in accordance with JIS K6217-3:2001 “Part 3: Method for determining specific surface area—CTAB adsorption method”.

[0278] [III] Silane coupling agent

[0279] The silane coupling agent contained in the composition of the present invention is not particularly limited as long as it is a silane compound having a hydrolyzable group and an organic functional group.

[0280] The hydrolyzable group is not particularly limited, and examples thereof include alkoxy groups, phenoxy groups, carboxyl groups, and alkenyloxy groups. Among these, alkoxy groups are preferred because they provide a more excellent effect of the present invention. When the hydrolyzable group is an alkoxy group, the alkoxy group preferably has 1 to 16 carbon atoms, more preferably 1 to 4 carbon atoms, because they provide a more excellent effect of the present invention. Examples of alkoxy groups having 1 to 4 carbon atoms include methoxy groups, ethoxy groups, and propoxy groups.

[0281] The organic functional group is not particularly limited, but is preferably a group capable of forming a chemical bond with an organic compound. Examples thereof include epoxy groups, vinyl groups, acryloyl groups, methacryloyl groups, amino groups, sulfide groups, mercapto groups, blocked mercapto groups (protected mercapto groups) (e.g., octanoylthio groups), etc. Among them, sulfide groups (particularly disulfide groups and tetrasulfide groups), mercapto groups, and blocked mercapto groups are preferred because they provide a more excellent effect of the present invention.

[0282] Specific examples of the silane coupling agent include bis(3-triethoxysilylpropyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(3-triethoxysilylpropyl)disulfide, mercaptopropyltrimethoxysilane, mercaptopropyltriethoxysilane, 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyl-tetrasulfide, trimethoxysilylpropyl-mercaptobenzothiazole tetrasulfide, triethoxysilylpropyl-methacrylate-monosulfide, dimethoxymethylsilylpropyl-N,N-dimethylthiocarbamoyl-tetrasulfide, and 3-octanoylthio-1-propyltriethoxysilane. These may be used alone or in combination of two or more.

[0283] [1] Suitable solutions

[0284] Since the effects of the present invention are more excellent, the silane coupling agent is preferably a compound represented by the following general formula (S).

[0285] (C n H 2n+1 O)3-Si-C m H 2m -S-CO-C k H 2k+1 General formula (S)

[0286] In the general formula (S), n represents an integer of 1 to 3, m represents an integer of 1 to 5 (preferably an integer of 2 to 4), and k represents an integer of 1 to 15 (preferably an integer of 5 to 10).

[0287] [2] Content

[0288] In the composition of the present invention, the content of the silane coupling agent is 3 to 30% by mass relative to the content of the silica (the total content of all silica including specific silica), and preferably 5 to 20% by mass for the purpose of achieving more excellent effects of the present invention.

[0289] In the composition of the present invention, the content of the silane coupling agent is preferably 1 to 30 parts by mass, more preferably 2 to 20 parts by mass, and even more preferably 3 to 10 parts by mass relative to 100 parts by mass of the rubber component, because the effects of the present invention are more excellent.

[0290] [IV] Optional Ingredients

[0291] The composition of the present invention may contain components (optional components) other than the above components as needed.

[0292] Examples of such components include fillers other than silica (e.g., carbon black), terpene resins (preferably aromatic modified terpene resins), thermally expandable microcapsules, zinc oxide (zinc white), stearic acid, antioxidants, waxes, processing aids, processing oils, liquid polymers, thermosetting resins, vulcanizing agents (e.g., sulfur), vulcanization accelerators, and other additives generally used in rubber compositions.

[0293] [1] Carbon black

[0294] The composition of the present invention preferably contains carbon black because the effects of the present invention are more excellent.

[0295] The carbon black is not particularly limited, and various grades such as SAF-HS, SAF, ISAF-HS, ISAF, ISAF-LS, IISAF-HS, HAF-HS, HAF, HAF-LS, FEF, GPF, and SRF may be used.

[0296] The nitrogen adsorption specific surface area (N2SA) of the carbon black is not particularly limited, but is preferably 50 to 200 m2 for the purpose of achieving the best effect of the present invention. 2 / g, more preferably 70 to 150 m 2 / g.

[0297] Here, the nitrogen adsorption specific surface area (N2SA) is a value obtained by measuring the amount of nitrogen adsorbed on the carbon black surface in accordance with JIS K6217-2:2001 "Part 2: Method for determining specific surface area - Nitrogen adsorption method - Single-point method".

[0298] [content]

[0299] In the composition of the present invention, the content of carbon black is not particularly limited, but is preferably 1 to 100 parts by mass, more preferably 2 to 10 parts by mass, relative to 100 parts by mass of the rubber component, because the effects of the present invention are more excellent.

[0300] [2] Specific alkyltriethoxysilane

[0301] Because the effects of the present invention are more excellent, the composition of the present invention preferably contains an alkyltriethoxysilane represented by the following general formula (I) (hereinafter also referred to as "specific alkyltriethoxysilane").

[0302]

[0303] In the above general formula (I), R 1 represents an alkyl group having 7 to 20 carbon atoms. Et represents an ethyl group.

[0304] Specific examples of the alkyl group having 7 to 20 carbon atoms include heptyl, octyl, nonyl, decyl, undecyl, and dodecyl. Among them, octyl and nonyl are preferred because they provide more excellent effects of the present invention.

[0305] [content]

[0306] In the composition of the present invention, the content of the specific alkyltriethoxysilane is not particularly limited, but is preferably 2.0 to 15.0% by mass relative to the content of the silica (the total content of all silica including the specific silica) for the purpose of achieving more excellent effects of the present invention.

[0307] [3] Thermoplastic resin

[0308] The composition of the present invention preferably contains a thermoplastic resin because the effects of the present invention are more excellent.

[0309] Examples of thermoplastic resins include natural resins such as terpene resins and rosin resins, and synthetic resins such as petroleum resins, coal resins, phenolic resins, and xylene resins. Among these, terpene resins are preferred because they provide superior effects of the present invention. Examples of terpene resins include α-pinene resins, β-pinene resins, limonene resins, hydrogenated limonene resins, dipentene resins, terpene phenol resins, terpene styrene resins, aromatic modified terpene resins, and hydrogenated terpene resins. Among these, aromatic modified terpene resins are preferred because they provide superior effects of the present invention.

[0310] [Softening point]

[0311] For reasons of greater effectiveness of the present invention, the softening point of the thermoplastic resin (particularly the aromatic modified terpene resin) is preferably 50°C or higher, more preferably 80°C or higher. For reasons of greater effectiveness of the present invention, the upper limit of the softening point is preferably 170°C or lower, more preferably 150°C or lower.

[0312] Here, the softening point is a softening point measured in accordance with JIS K2207:1996.

[0313] [content]

[0314] In the composition of the present invention, the content of the thermoplastic resin (particularly the aromatic modified terpene resin) is preferably 1 to 20 parts by mass, more preferably 1 to 15 parts by mass, and even more preferably 2 to 15 parts by mass relative to 100 parts by mass of the rubber component, because the effects of the present invention are more excellent.

[0315] [4] Liquid diene rubber

[0316] The composition of the present invention preferably contains a liquid diene rubber because the effects of the present invention are more excellent. The liquid diene rubber is preferably liquid SBR or liquid BR, and more preferably liquid BR because the effects of the present invention are more excellent.

[0317] [Suitable solution]

[0318] For the reason that the effects of the present invention are more excellent, the liquid diene rubber preferably has a functional group derived from a silane compound represented by the following general formula (II).

[0319]

[0320] In the general formula (II), R 1 is a divalent alkylene group having 1 to 6 carbon atoms, R 2 、R 3 and R 4 Each independently represents a methoxy group, an ethoxy group, a phenoxy group, a methyl group, an ethyl group or a phenyl group. 2 、R 3 and R 4 At least one of them is a methoxy group, an ethoxy group or a phenoxy group.

[0321] [Molecular weight]

[0322] For the reason that the effects of the present invention are more excellent, the weight average molecular weight (Mw) of the liquid diene rubber is preferably 3,000 or more and less than 100,000, and more preferably 5,000 or more and less than 80,000.

[0323] [content]

[0324] In the composition of the present invention, the content of the liquid diene rubber relative to the content of the silica (the total content of all silica including specific silica) is preferably 1.0 to 15.0% by mass, and more preferably 5.0 to 10.0% by mass, for the reason that the effects of the present invention are more excellent.

[0325] [B] Tires

[0326] The tire of the present invention is manufactured using the composition of the present invention. The tire of the present invention is preferably a pneumatic tire, which can be filled with air, an inert gas such as nitrogen, or other gases. Among them, a pneumatic tire in which the composition of the present invention is used (disposed on) the tire tread (tread cap) is preferred.

[0327] Figure 1 A partial cross-sectional schematic diagram of a tire showing an example of an embodiment of the tire of the present invention is shown, but the tire of the present invention is not limited to Figure 1 The scheme shown.

[0328] exist Figure 1 In the figure, reference numeral 1 denotes a bead portion, reference numeral 2 denotes a sidewall portion, and reference numeral 3 denotes a tire tread portion.

[0329] A carcass layer 4 in which fiber cords are embedded is mounted between the pair of left and right bead portions 1 , and the end portions of the carcass layer 4 are folded back and rolled up from the inside to the outside of the tire around the bead core 5 and the bead filler 6 .

[0330] Furthermore, in the tire tread portion 3 , a belt layer 7 is arranged outside the carcass layer 4 and extends around the tire.

[0331] Furthermore, a rim cushion 8 is arranged at a portion of the bead portion 1 that contacts the rim.

[0332] Note that the tire tread portion 3 is formed from the composition of the present invention.

[0333] The tire of the present invention can be manufactured according to a conventionally known method. In addition, as the gas filled in the tire, in addition to normal air or air with an adjusted oxygen partial pressure, inert gases such as nitrogen, argon, and helium can also be used.

[0334] Example

[0335] Hereinafter, the present invention will be described in further detail with reference to Examples, but the present invention is not limited thereto.

[0336] [Production of Specific Conjugated Diene Rubber 1]

[0337] The specific conjugated diene rubber 1 was produced as follows.

[0338] [Process A]

[0339] In an 800 ml container purged with nitrogen, 140.89 g of cyclohexane and 3.0 mmol of tetramethylethylenediamine were added, followed by 30.0 mmol of n-butyllithium. Subsequently, 113.6 g of isoprene and 9.2 g of styrene were slowly added, and the mixture was reacted in a container at 50°C for 120 minutes to obtain a polymer block (A) having active terminals. This polymer block (A) had a weight-average molecular weight (Mw) of 6,500, a molecular weight distribution (Mw / Mn) of 1.10, a styrene monomer unit content of 7.5% by mass, an isoprene monomer unit content of 92.5% by mass, and a vinyl bond content of 7.0% by mass in the isoprene monomer units.

[0340] [Process B]

[0341] In an autoclave equipped with a stirrer, 6400 g of cyclohexane, 2.95 mmol of tetramethylethylenediamine, 585 g of 1,3-butadiene, 615 g of styrene, and bis(diethylamino)methylvinylsilane (in the above general formula (1), X 1 = chemical single bond, X 2 and X 3 =diethylamino, X 4 =methyl compound) was added, followed by 7.01 mmol of n-butyllithium. 0.51 mmol of the polymer block (A) having active terminals was added, calculated as lithium atom content, and polymerization was initiated at 40°C. Ten minutes after the start of polymerization, 300 g of 1,3-butadiene was continuously added over 60 minutes. After the continuous additions were completed, the polymerization reaction was continued for a further 20 minutes, and the polymerization conversion rate was confirmed to be in the range of 95% to 100%. This procedure yielded a conjugated diene polymer chain having active terminals, comprising polymer block (A) and polymer block (B).

[0342] Bis(diethylamino)methylvinylsilane

[0343]

[0344] [Process C]

[0345] Next, the polyorganosiloxane represented by the following formula (9) was added in such a manner that the content of -Si-O- repeating units became 7.15 mmol, and the reaction was allowed to proceed for 30 minutes. Then, methanol in an amount equivalent to 2 times the molar amount of n-butyl lithium used was added as a polymerization inhibitor to obtain a solution containing a conjugated diene rubber. To this solution, 0.20 parts by mass of Ilganox 1520L (manufactured by BASF) as an antioxidant was added relative to 100 parts by mass of the conjugated diene rubber, and 15.0 parts by mass of an extender oil (trade name "Aromax T-DAE", manufactured by JX Mining and Chemical Industries, Ltd.) relative to 100 parts by mass of the conjugated diene rubber was added. After that, the solvent was removed by steam stripping and vacuum dried at 60°C for 24 hours to obtain a solid conjugated diene rubber.

[0346] The resulting conjugated diene rubber had a weight-average molecular weight (Mw) of 590,000, a styrene monomer unit content of 41% by mass, a vinyl bond content of 25% by mass, and a bis(diethylamino)methylvinylsilane monomer unit content of 0.06% by mass.

[0347] The obtained conjugated diene rubber had a glass transition temperature of -26°C.

[0348]

[0349] X 9 , X 12 ,R 3 ~R 5 ,R 7 ~R IO :-CH3

[0350] The resulting conjugated diene rubber comprises a polymer block (A) containing isoprene monomer units and styrene monomer units, and a polymer block (B) containing 1,3-butadiene monomer units, styrene monomer units, and bis(diethylamino)methylvinylsilane monomer units (units of a vinyl compound containing a functional group capable of interacting with silica), and a terminally modified structure formed by a polyorganosiloxane (siloxane compound) represented by the above formula (9). The weight-average molecular weight (Mw) of the polymer block (A) is in the range of 1,000 to 30,000, and the overall weight-average molecular weight (Mw) is in the range of 50,000 to 5,000,000. The overall styrene monomer unit content (aromatic vinyl monomer unit content) is 30 to 45% by mass, and the overall vinyl bond content is 15 to 35% by mass.

[0351] Therefore, the obtained conjugated diene rubber corresponds to the above-mentioned specific conjugated diene rubber.

[0352] The obtained conjugated diene rubber is also referred to as specific conjugated diene rubber 1.

[0353] [Comparison of conjugated diene rubbers]

[0354] In step B, a conjugated diene rubber was produced by the same procedure as that for producing the specific conjugated diene rubber 1, except that the amounts of tetramethylethylenediamine, 1,3-butadiene, and styrene were changed to 0.71 mmol, 763 g, and 28.7 g, respectively.

[0355] The resulting conjugated diene rubber had a weight-average molecular weight (Mw) of 750,000, a styrene monomer unit content of 28% by mass, and a vinyl bond content of 59% by mass. Furthermore, the bis(diethylamino)methylvinylsilane monomer unit content in the resulting conjugated diene rubber was 0.15% by mass. Furthermore, the resulting conjugated diene rubber had a glass transition temperature of -21°C.

[0356] The resulting conjugated diene rubber comprises a polymer block (A) containing isoprene monomer units and styrene monomer units, and a polymer block (B) containing 1,3-butadiene monomer units, styrene monomer units, and bis(diethylamino)methylvinylsilane monomer units (units of a vinyl compound containing a functional group capable of interacting with silica), and has a modified structure at the terminal formed by a polyorganosiloxane (siloxane compound) represented by the above formula (9). Furthermore, the weight-average molecular weight (Mw) of the polymer block (A) is in the range of 1,000 to 30,000, and the overall weight-average molecular weight (Mw) is in the range of 50,000 to 5,000,000. On the other hand, the overall styrene monomer unit content (aromatic vinyl monomer unit content) of the resulting conjugated diene rubber is outside the range of 30 to 45% by mass, and the overall vinyl bond content is outside the range of 15 to 35% by mass, and therefore does not correspond to the above-mentioned specific conjugated diene rubber.

[0357] The obtained conjugated diene rubber is also referred to as a comparative conjugated diene rubber.

[0358] [Preparation of Tire Rubber Composition]

[0359] The components shown in Table 1 below were blended in the ratios (parts by mass) shown in the table.

[0360] Specifically, the components listed in Table 1 below, excluding sulfur and a vulcanization accelerator, were first heated to approximately 140°C using a 1.7-liter closed Banbury mixer, mixed for 5 minutes, then discharged and cooled to room temperature to obtain a masterbatch. Furthermore, sulfur and a vulcanization accelerator were mixed with the obtained masterbatch using the Banbury mixer to obtain a tire rubber composition.

[0361] In addition, when the rubber component is an oil-extended product, parts by mass represent the net weight of the rubber (amount excluding oil).

[0362] [evaluate]

[0363] The obtained tire rubber composition was evaluated as follows.

[0364] 〔Temperature dependence of rolling resistance〕

[0365] The obtained rubber composition for a tire (unvulcanized) was press-vulcanized in a mold (15 cm×15 cm×0.2 cm) at 160° C. for 40 minutes to produce a vulcanized rubber sheet.

[0366] The obtained vulcanized rubber sheet was measured for tan δ (tan δ (10°C)) using a viscoelasticity spectrometer (manufactured by Toyo Seiki Seisaku-sho, Ltd.) in accordance with JIS K6394:2007 under the conditions of a tensile strain rate of 10% ± 2%, a frequency of 20 Hz, and a temperature of 10°C. Similarly, tan δ (tan δ (40°C)) was measured at a temperature of 40°C. The following parameters were then determined. It should be noted that when tan δ (10°C) and tan δ (40°C) were the same value, the following parameters were set to 1.

[0367] Parameter = (the smaller of tanδ(10°C) and tanδ(40°C)) / (the larger of tanδ(10°C) and tanδ(40°C))

[0368] The results are shown in Table 1. The results are expressed as an index with Comparative Example 1 being 100. A larger index indicates a smaller difference between tan δ (10°C) and tan δ (40°C), and a smaller temperature dependence of rolling resistance. An index exceeding 100 is preferred.

[0369] Wet road performance

[0370] Similar to the above-mentioned temperature dependency of rolling resistance, tan δ (tan δ (0° C.)) was measured at a temperature of 0° C.

[0371] The results are shown in Table 1. The results are expressed as an index with Comparative Example 1 being 100. A larger index indicates better wet performance. A value of 103 or greater is preferred.

[0372] [Table 1]

[0373]

[0374] The details of each component in Table 1 are as follows.

[0375] Specific conjugated diene rubber 1: the specific conjugated diene rubber 1 produced as described above (as described above, the specific conjugated diene rubber 1 corresponds to the specific conjugated diene rubber)

[0376] Comparative conjugated diene rubber: the comparative conjugated diene rubber produced as described above (as described above, the comparative conjugated diene rubber does not correspond to the specific conjugated diene rubber)

[0377] Rubber component 1: Solution-polymerized styrene-butadiene rubber having terminal polyorganosiloxane groups and isoprene blocks. (Oil-extended product (containing 25 parts by mass of extender oil per 100 parts by mass of SBR), styrene monomer unit content: 43% by mass, vinyl bond content: 30% by mass, weight-average molecular weight: 650,000, Tg: -26°C, manufactured by Zeon Japan Co., Ltd.) (Rubber component 1 does not contain units of a vinyl compound containing a functional group capable of interacting with silica and therefore does not correspond to the aforementioned specific conjugated diene rubber.)

[0378] BR1220: Nipol BR1220 (butadiene rubber, weight-average molecular weight: 460,000, glass transition temperature: -106°C, manufactured by Zeon Japan Co., Ltd.) (BR1220 is a butadiene rubber with a glass transition temperature of -85°C or less, and therefore corresponds to the above-mentioned specific butadiene rubber)

[0379] BR1261: Modified butadiene rubber having a terminal modifying group containing a heteroatom (weight-average molecular weight: 490,000, glass transition temperature: -93°C) (BR1261 is a modified butadiene rubber with a glass transition temperature of -85°C or less and therefore corresponds to the above-mentioned specific butadiene rubber)

[0380] Specific modified butadiene rubber 1: BR54 manufactured by JSR Corporation (Specific modified butadiene rubber 1 corresponds to the above-mentioned specific butadiene rubber and the above-mentioned specific modified butadiene rubber)

[0381] NS612: NS612 manufactured by Zeon Japan Co., Ltd. (solution-polymerized SBR, styrene monomer unit content: 15% by mass, vinyl bond content: 31% by mass, weight-average molecular weight: 440,000, Tg-61°C) (NS612 does not correspond to the above-mentioned specific conjugated diene rubber)

[0382] 7000GR: ULTRASIL 7000GR (silicon dioxide, CTAB adsorption specific surface area: 160m 2 / g, manufactured by Evonik)

[0383] 9100GR: ULTRASIL 9100GR (silicon dioxide, CTAB adsorption specific surface area: 200m 2 / g, manufactured by Evonik)

[0384] ·N339: Sewage Fluid N339 (carbon black, manufactured by Kempinski Co., Ltd.)

[0385] NXT: A silane coupling agent represented by the above general formula (S) (wherein, in the above general formula (S), n=2, m=3, and k=7.)

[0386] Zinc oxide: 3 types of zinc oxide (manufactured by Seido Chemical Industry Co., Ltd.)

[0387] Stearic acid: stearic acid (manufactured by NOF Corporation)

[0388] Antioxidant: Ozonone 6C (manufactured by Seiko Chemical Co., Ltd.)

[0389] ·Processing oil: Ekostor No. 4S (manufactured by Showa Seiko Oil Co., Ltd.)

[0390] Alkylsilane: Octyltriethoxysilane (KBE-3083, manufactured by Shin-Etsu Chemical Co., Ltd.) (the alkylsilane corresponds to the above-mentioned specific alkyltriethoxysilane)

[0391] Thermoplastic resin: YS resin TO125 manufactured by Yashara Chemical Co., Ltd. (aromatic modified terpene resin, softening point: 125°C)

[0392] Modified LBR: A ​​modified liquid diene rubber produced as follows

[0393] The fully dried 5L autoclave was purged with nitrogen, 1200g of hexane and 22g of n-butyllithium (17% by mass hexane solution) were added, and after heating to 50°C, 1460g of butadiene was added successively under stirring while controlling the polymerization temperature to 50°C, and polymerized for 1 hour. Methanol was then added to stop the polymerization reaction, and a polymer solution was obtained. Water was added to the obtained polymer solution and stirred, and the polymer solution was washed with water. After stirring was terminated and the polymer solution phase was confirmed to be separated from the aqueous phase, the water was separated. The polymer solution after washing was vacuum dried at 70°C for 24 hours to obtain an unmodified liquid diene rubber.

[0394] Next, 700 g of the unmodified liquid diene rubber was placed in a 1 L autoclave and stirred at 60°C for 3 hours while degassing with nitrogen. 1.0 g of 1,1-bis(tert-hexylperoxy)cyclohexane and 25 g of (3-mercaptopropyl)trimethoxysilane were added, and the mixture was reacted at 105°C for 8 hours to obtain a modified liquid diene rubber. The weight-average molecular weight of the resulting modified liquid diene rubber was 55,000. The resulting modified liquid diene rubber was a liquid BR having functional groups derived from the silane compound represented by the general formula (II).

[0395] Sulfur: Jinhua ink-infused micronized sulfur (sulfur content 95.24% by mass, manufactured by Tsurumi Chemical Industry Co., Ltd.)

[0396] Vulcanization accelerator (CZ): Nokucela CZ-G manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0397] Vulcanization accelerator (DPG): 1,3-diphenylguanidine (Soxinol DG, manufactured by Sumitomo Chemical Co., Ltd.)

[0398] In Table 1, St represents the styrene monomer unit content (mass %), Vn represents the vinyl bond content (mass %), and Mw represents the weight average molecular weight (×10 4 ), Tg represents the glass transition temperature (°C).

[0399] As apparent from Table 1, Examples 1 to 8, in which the specific conjugated diene rubber and the specific butadiene rubber were used in combination in predetermined amounts, had low temperature dependence of rolling resistance and exhibited excellent wet performance.

[0400] A comparison between Example 1 and Example 2 (a comparison of examples using 7000GR as silica and BR1220 as the specific butadiene rubber) shows that Example 1, in which the content of the specific conjugated diene rubber in the rubber component is 50% by mass or greater, exhibits superior wet performance.

[0401] A comparison of Examples 1, 3, and 4 (comparison of examples using 7000GR as silica and containing 75% by mass of the specific conjugated diene rubber in the rubber component) shows that Examples 3 and 4, in which the specific butadiene rubber is a butadiene rubber having a modified group containing a heteroatom at at least one terminal, exhibited a lower temperature dependence of rolling resistance and superior wet performance. In particular, Example 4, in which the specific butadiene rubber is the aforementioned specific modified butadiene rubber, exhibited an even lower temperature dependence of rolling resistance.

[0402] Comparison between Example 4 and Example 5 (comparison between examples differing only in the type of silica) shows that Example 5, in which the silica contains 20 parts by mass or more of the specific silica, exhibits more excellent wet performance.

[0403] Furthermore, a comparison between Example 5 and Example 6 (a comparison between versions differing only in the presence or absence of alkylsilane) shows that Example 6 containing the specific alkyltriethoxysilane exhibits more excellent wet performance.

[0404] Furthermore, a comparison between Example 5 and Example 7 (a comparison between examples differing only in the presence or absence of modified LBR) shows that Example 7 containing a liquid diene rubber has a smaller temperature dependency of rolling resistance and exhibits superior wet performance.

[0405] Furthermore, a comparison between Example 5 and Example 8 (a comparison between examples differing only in the presence or absence of thermoplastic resin) shows that Example 8 containing a thermoplastic resin has a smaller temperature dependency of rolling resistance and exhibits superior wet performance.

[0406] On the other hand, in Comparative Examples 1, 3, and 6, which do not contain the specific conjugated diene rubber, Comparative Example 2, which contains the specific conjugated diene rubber but the content in the rubber component is less than 35% by mass, and Comparative Examples 4 to 5, which do not contain the specific butadiene rubber, at least one of the temperature dependence of rolling resistance and wet performance is insufficient.

[0407] Explanation of symbols

[0408] 1 Bead

[0409] 2 Sidewall

[0410] 3 Tire tread

[0411] 4 carcass layers

[0412] 5 Bead core

[0413] 6 Bead filler

[0414] 7 Belt

[0415] 8 Rim cushions.

Claims

1. A rubber composition for a tire, comprising a rubber component, silica, and a silane coupling agent. The rubber component contains a specific conjugated diene rubber and a specific butadiene rubber, In the rubber component, the content of the specific conjugated diene rubber is 35% by mass or more, and the content of the specific butadiene rubber is 15% by mass or more. The specific conjugated diene rubber is: A conjugated diene rubber comprising a polymer block (A) containing 50% by mass or more of isoprene monomer units and a polymer block (B) containing 55 to 65% by mass of 1,3-butadiene monomer units, and having a modified structure formed with a siloxane compound at at least one terminal. And the specific conjugated diene rubber is: At least one of the polymer block (A) and the polymer block (B) contains a unit of a vinyl compound 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 1,000 to 30,000, and the overall weight average molecular weight Mw is in the range of 50,000 to 5,000,000. The total aromatic vinyl monomer unit content is 30 to 45% by mass. A conjugated diene rubber having a total vinyl bond content of 15 to 35% by mass, The specific butadiene rubber is a butadiene rubber having a glass transition temperature of -85°C or lower. The content of the silica is 50 to 150 parts by mass relative to 100 parts by mass of the rubber component. The content of the silane coupling agent is 3 to 30% by mass relative to the content of the silicon dioxide. The silane coupling agent is a silane compound having a hydrolyzable group and an organic functional group, wherein the organic functional group is an epoxy group, a vinyl group, an acryloyl group, a methacryloyl group, an amino group, a thioether group, a mercapto group or a blocked mercapto group. The siloxane compound is a polyorganosiloxane represented by the following general formula (4): In the above general formula (4), R 3 ~R 10 is 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; 9 and X 12 X is any group selected from 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 containing an epoxy group, and they are the same or different; 10 is an alkoxy group having 1 to 5 carbon atoms, or a group having 4 to 12 carbon atoms containing an epoxy group, wherein X 10 When there are multiple, they are the same or different from each other; X 11 A group containing 2 to 20 repeating units of alkylene glycol, wherein X 11 When there are multiple moieties, they are 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. 2 . The tire rubber composition according to claim 1 , wherein the specific conjugated diene rubber has an aromatic vinyl monomer unit content of 35 to 45% by mass.

3. The tire rubber composition according to claim 1 or 2, wherein the specific butadiene rubber is a modified butadiene rubber having a modifying group containing a heteroatom at at least one terminal, and the modifying group containing a heteroatom is a hydroxyl group, an epoxy group, a carboxyl group, or a hydrocarbyloxysilyl group.

4. The tire rubber composition according to claim 1 or 2, wherein the silica comprises a CTAB adsorption specific surface area of ​​190 m 2 / g or more of silica, that is, 20 parts by mass or more of specific silica.

5. The tire rubber composition according to claim 1 or 2, further comprising an alkyltriethoxysilane represented by the following general formula (I): The content of the alkyltriethoxysilane is 2.0 to 15.0% by mass relative to the content of the silicon dioxide. In the general formula (I), R 1 represents an alkyl group having 7 to 20 carbon atoms, and Et represents an ethyl group.

6. The tire rubber composition according to claim 1 or 2, further comprising a liquid diene rubber having a weight average molecular weight of 3,000 or more, The content of the liquid diene rubber is 1.0 to 15.0% by mass relative to the content of the silica.

7. The tire rubber composition according to claim 6, wherein the liquid diene rubber has a functional group derived from a silane compound represented by the following general formula (II): In the general formula (II), R 1 is a divalent alkylene group having 1 to 6 carbon atoms, R 2 、R 3 and R 4 Each independently represents a methoxy group, an ethoxy group, a phenoxy group, a methyl group, an ethyl group or a phenyl group, wherein R 2 、R 3 and R 4 At least one of them is a methoxy group, an ethoxy group or a phenoxy group.

8. The tire rubber composition according to claim 1 or 2, further comprising a thermoplastic resin having a softening point of 50°C or higher. The content of the thermoplastic resin is 1 to 20 parts by mass based on 100 parts by mass of the rubber component. 9 . A tire produced using the rubber composition for a tire according to claim 1 .

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