Rubber composition for tires and tires

Abstract

To provide a rubber composition for tires excellent in shrink resistance, heat sag resistance and wear resistance and a tire.SOLUTION: A rubber composition for tires comprises a rubber composition having a content of specific conjugated diene rubber of 35 mass% or larger and a content of specific copolymer rubber of 25 mass% or larger and silica and a silane coupling agent, in which the specific conjugated diene rubber is provided with a block A containing an isoprene unit and a block B containing a butadiene unit, is provided with a modification structure due to a siloxane compound at a terminal, at least one of the A and B contains a unit of a vinyl compound capable of mutually interactive with silica, the Mw of the A is 1,000 to 30,000, an entire Mw is 50,000 to 5,000,000, a total aromatic vinyl content is 30 to 45 mass%, and the specific copolymer rubber has an aromatic vinyl content of 23 to 50 mass%, a difference with the aromatic vinyl content of a total of the specific conjugated rubber is 10 mass% or smaller, and the Mw is 800,000 or larger.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] 2. Description of the Related Art Conventionally, compositions containing modified conjugated diene rubber and silica have been known as rubber compositions used for tires (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2019 / 073828 Summary of the Invention [Problem to be solved by the invention]

[0004] Recently, with the increasing demand for higher safety levels, tires are being required to have further improved heat sagging resistance (resistance to loss of grip during driving) and abrasion resistance. In addition, rubber compositions used in tires are being required to have improved shrink resistance (resistance to shrinking during extrusion molding). Under these circumstances, the present inventors prepared a rubber composition for tires with reference to Patent Document 1, and evaluated its shrink resistance, as well as heat sagging resistance and abrasion resistance when made into a tire. However, it became clear that the resulting composition did not necessarily satisfy the levels currently required.

[0005] In view of the above-mentioned circumstances, the present invention aims to provide a rubber composition for tires which has excellent shrink resistance and, when made into a tire, has excellent heat sagging resistance and abrasion resistance, and a tire manufactured using the rubber composition for tires. In the following, the heat sagging resistance and abrasion resistance when made into a tire will also be simply referred to as heat sagging resistance and abrasion resistance. [Means for solving the problem]

[0006] As a result of intensive research into the above-mentioned problems, the present inventors have found that the above-mentioned problems can be solved by using a specific modified conjugated diene rubber and a specific copolymer rubber in predetermined amounts and by making the aromatic monomer units of both rubbers have a predetermined relationship, thereby completing the present invention. That is, the present inventors have found that the above problems can be solved by the following configuration.

[0007] (1) A rubber composition comprising a rubber component, silica, and a silane coupling agent, The rubber component contains a specific conjugated diene rubber and a specific copolymer 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 copolymer rubber is 25% by mass or more, The specific conjugated diene rubber is 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 siloxane compound-modified structure at at least one end, At least one of the polymer block (A) and the polymer block (B) contains a vinyl compound unit containing a functional group capable of interacting with silica, The weight average molecular weight (Mw) of the polymer block (A) is in the range of 1,000 to 30,000, and the total weight average molecular weight (Mw) is in the range of 50,000 to 5,000,000; A conjugated diene rubber having a total aromatic vinyl monomer unit content of 30 to 45 mass %, The specific copolymer rubber is an aromatic vinyl-conjugated diene copolymer rubber other than the specific conjugated diene rubber, an aromatic vinyl monomer unit content of 23 to 50 mass%, and a difference from the aromatic vinyl monomer unit content of the entire specific conjugated diene rubber is 10 mass% or less; An aromatic vinyl-conjugated diene copolymer rubber having a weight average molecular weight (Mw) of 800,000 or more, The content of the silica is 50 to 150 parts by mass based on 100 parts by mass of the rubber component, The rubber composition for tires, wherein the content of the silane coupling agent is 3 to 30 mass % based on the content of the silica. (2) The specific conjugated diene rubber has an aromatic vinyl monomer unit content of 35 to 45 mass %, The rubber composition for tires according to the above (1), wherein the specific copolymer rubber has an aromatic vinyl monomer unit content of 30 to 50 mass %. (3) Furthermore, it contains a thermoplastic resin with a softening point of 50°C or higher, The rubber composition for tires according to the above (1) or (2), wherein the content of the thermoplastic resin is 1 to 20 parts by mass per 100 parts by mass of the rubber component. (4) The above silica has a CTAB adsorption specific surface area of ​​190 m 2 The rubber composition for tires according to any one of the above (1) to (3), comprising 20 parts by mass or more of specific silica, which is silica having a molecular weight of 100 / g or more. (5) Further, the composition contains an alkyltriethoxysilane represented by the general formula (I) described later, The rubber composition for a tire according to any one of the above (1) to (4), wherein the content of the alkyltriethoxysilane is 2.0 to 15.0 mass % based on the content of the silica. (6) Furthermore, the liquid diene rubber has a weight average molecular weight of 3,000 or more. The rubber composition for tires according to any one of the above (1) to (5), wherein the content of the liquid diene rubber is 1.0 to 15.0 mass % based on the content of the silica. (7) The rubber composition for tires according to the above (6), wherein the liquid diene rubber has a functional group derived from a silane compound represented by general formula (II) described below. (8) A tire produced using the rubber composition for tires according to any one of (1) to (7) above. Effect of the Invention

[0008] As described below, according to the present invention, it is possible to provide a rubber composition for tires which has excellent shrink resistance and, when made into a tire, has excellent heat sagging resistance and abrasion resistance, and a tire manufactured using the rubber composition for tires. [Brief description of the drawings]

[0009] [Figure 1] 1 is a partial cross-sectional schematic view showing an example of an embodiment of a tire of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The rubber composition for tires of the present invention and a tire produced using the rubber composition for tires will be described below. In this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits. In addition, each component contained in the rubber composition for tires of the present invention may be used alone or in combination of two or more. Here, when two or more types of each component are used in combination, the content of the component refers to the total content unless otherwise specified. In this specification, the "content of monomer units" is also referred to as the "monomer unit content."

[0011] [A] Rubber composition for tires The rubber composition for tires of the present invention (hereinafter also referred to as "the composition of the present invention") has The rubber composition contains a rubber component, silica, and a silane coupling agent, The rubber component contains a specific conjugated diene rubber and a specific copolymer rubber, In the rubber component, the content of the specific conjugated diene rubber is 35% by mass or more, and the content of the aromatic vinyl-conjugated diene copolymer rubber is 25% by mass or more, The specific conjugated diene rubber is 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 siloxane compound-modified structure at at least one end, At least one of the polymer block (A) and the polymer block (B) contains a vinyl compound unit containing a functional group capable of interacting with silica, The weight average molecular weight (Mw) of the polymer block (A) is in the range of 1,000 to 30,000, and the total weight average molecular weight (Mw) is in the range of 50,000 to 5,000,000; A conjugated diene rubber having a total aromatic vinyl monomer unit content of 30 to 45 mass %, The specific copolymer rubber is an aromatic vinyl-conjugated diene copolymer rubber other than the specific conjugated diene rubber, an aromatic vinyl monomer unit content of 23 to 50 mass%, and a difference from the aromatic vinyl monomer unit content of the entire specific conjugated diene rubber is 10 mass% or less; An aromatic vinyl-conjugated diene copolymer rubber having a weight average molecular weight (Mw) of 800,000 or more, The content of the silica is 50 to 150 parts by mass based on 100 parts by mass of the rubber component, In the rubber composition for tires, the content of the silane coupling agent is 3 to 30 mass % relative to the content of the silica.

[0012] The composition of the present invention has the above-mentioned structure, and therefore it is believed that the above-mentioned effects can be obtained. In particular, it is believed that the composition is characterized in that the specific conjugated diene rubber and the specific copolymer rubber are used in combination, and that the aromatic monomer units of both rubbers have a predetermined relationship. The specific conjugated diene rubber contained in the composition of the present invention contains a vinyl compound unit containing a functional group capable of interacting with silica in the polymer chain. The specific conjugated diene rubber also has a modified structure with a siloxane compound at the end. These sites in the specific conjugated diene rubber interact with the silica in the composition, so that the mobility of the specific conjugated diene rubber in the composition of the present invention is suppressed, and as a result, the composition of the present invention is considered to exhibit excellent shrink resistance. Furthermore, the composition of the present invention uses a specific copolymer rubber having a high molecular weight in addition to the specific conjugated diene rubber. The specific copolymer rubber is considered to contribute to the heat sagging resistance and wear resistance of the tire. Here, the aromatic vinyl monomer unit content of the specific conjugated diene rubber and the aromatic vinyl monomer unit content of the specific copolymer rubber are in a predetermined relationship, so that the two are easily compatible. Therefore, the composition of the present invention maintains the above-mentioned excellent shrink resistance, and is considered to be excellent in heat sagging resistance and wear resistance when made into a tire.

[0013] Each component contained in the composition of the present invention will be described below.

[0014] [I] Rubber component The rubber component contained in the composition of the present invention contains a specific conjugated diene rubber and a specific copolymer rubber which is an aromatic vinyl-conjugated diene copolymer rubber other than the specific conjugated diene 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 copolymer rubber is 25% by mass or more. The rubber component may contain a rubber component (other rubber component) that does not fall under either the specific conjugated diene rubber or the specific copolymer rubber. The rubber component is preferably in a solid state.

[0015] [1] Specific conjugated diene rubber As described above, the rubber component contains the specific conjugated diene rubber. The specific conjugated diene rubber is 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 siloxane compound-modified structure at at least one end, At least one of the polymer block (A) and the polymer block (B) contains a vinyl compound unit containing a functional group capable of interacting with silica, The weight average molecular weight (Mw) of the polymer block (A) is in the range of 1,000 to 30,000, and the total weight average molecular weight (Mw) is in the range of 50,000 to 5,000,000; The conjugated diene rubber has a total aromatic vinyl monomer unit content of 30 to 45 mass %. In addition, since the specific conjugated diene rubber has a total aromatic vinyl monomer unit content of 30 to 45 mass %, at least one of the polymer block (A) and the polymer block (B) contains an aromatic vinyl monomer unit.

[0016] [Polymer block (A)] The polymer block (A) is not particularly limited as long as it contains an isoprene monomer unit (preferably contains an isoprene monomer unit as a main component), and may be composed of only an isoprene monomer unit, or may be composed of an isoprene monomer unit and a monomer unit other than an isoprene monomer unit. In this case, a suitable example of the monomer unit other than an isoprene monomer unit is an aromatic vinyl monomer unit, and the polymer block (A) of the present invention preferably contains an aromatic vinyl monomer unit in addition to an isoprene monomer unit.

[0017] [Isoprene monomer unit content] 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. 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) within the above range, when a compounding agent such as silica is compounded with the conjugated diene rubber, the affinity between the conjugated diene rubber and the compounding agent such as silica can be further increased, and the obtained rubber cross-linked product can have excellent low heat generation properties.

[0018] [Vinyl bond content in isoprene monomer unit] The vinyl bond content in the isoprene monomer unit in the polymer block (A) is preferably 3 to 90 mass%, more preferably 5 to 80 mass%. By setting the vinyl bond content in the isoprene monomer unit within the above range, the low heat build-up property of the obtained cross-linked rubber product can be further improved. In this specification, the vinyl bond content in the isoprene monomer unit refers to the total amount of the isoprene monomer unit having a 1,2-structure and the isoprene monomer unit having a 3,4-structure in the isoprene monomer unit.

[0019] [Aromatic vinyl compounds for forming aromatic vinyl monomer units] Examples of aromatic vinyl compounds for forming aromatic vinyl monomer units include styrene, methylstyrene, ethylstyrene, t-butylstyrene, α-methylstyrene, α-methyl-p-methylstyrene, chlorostyrene, bromostyrene, methoxystyrene, dimethylaminomethylstyrene, dimethylaminoethylstyrene, diethylaminomethylstyrene, diethylaminoethylstyrene, cyanoethylstyrene, and vinylnaphthalene. Among these, styrene is preferred. The content (aromatic vinyl monomer unit content) (for example, styrene monomer unit content) of aromatic vinyl monomer units (for example, styrene monomer unit content) in the polymer block (A) is preferably 50% by mass or less, more preferably 30% by mass or less, and even more preferably 10% by mass or less. The lower limit of the aromatic vinyl monomer unit content is not particularly limited, but is preferably 1% by mass or more.

[0020] [Vinyl compound units containing functional groups capable of interacting with silica] In addition, the specific conjugated diene rubber contains a vinyl compound unit containing a functional group capable of interacting with silica in at least one of the polymer block (A) and the polymer block (B) described later. In the following, a case where the polymer block (A) contains such a vinyl compound unit containing a functional group capable of interacting with silica will be described as an example, but since the vinyl compound unit containing a functional group capable of interacting with silica only needs to be contained in at least one of the polymer block (A) and the polymer block (B) described later, when the vinyl compound unit containing a functional group capable of interacting with silica is contained in the polymer block (B) described later, it is not necessarily required that the vinyl compound unit is contained in the polymer block (A).

[0021] <Vinyl compound containing a functional group capable of interacting with silica> The vinyl compound containing a functional group capable of interacting with silica for forming the unit of the vinyl compound containing a functional group capable of interacting with silica can be a compound containing a functional group capable of interacting with silica and a vinyl group, and is not particularly limited.Here, the functional group capable of interacting with silica is a functional group that can form a covalent bond between the functional group and the silica surface, or can form an intermolecular force weaker than a covalent bond (for example, ion-dipole interaction, dipole-dipole interaction, hydrogen bond, van der Waals force, etc.).Such a functional group capable of interacting with silica is not particularly limited, but can include a nitrogen atom-containing functional group, a silicon atom-containing functional group, an oxygen atom-containing functional group, etc., and among these, a silicon atom-containing functional group is preferred from the viewpoint of high interaction with silica.

[0022] (Preferred embodiment) As a preferred embodiment of the vinyl compound containing a functional group capable of interacting with silica, a vinyl compound containing a silicon atom-containing functional group can be suitably used, for example, a compound represented by the following general formula (1).

[0023] [ka] In the above general formula (1), X 1 represents a chemical single bond or a hydrocarbylene group, and 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.

[0024] In the above general formula (1), X 1 is a chemical single bond or a hydrocarbylene group, preferably a chemical single bond. Examples of the hydrocarbylene group include an alkylene group, an alkenediyl group, an arylene group, and a group in which an arylene group and an alkylene group are bonded together. Examples of the alkylene group include a methylene group, an ethylene group, and a trimethylene group. Examples of the alkene diyl group include a vinylene group and an ethylene-1,1-diyl group. Examples of the arylene group include a phenylene group, a naphthylene group, and a biphenylene group. Examples of the group in which an arylene group and an alkylene group are bonded include a group in which a phenylene group and a methylene group are bonded, and a group in which a phenylene group and an ethylene group are bonded. X 1 When X is a hydrocarbylene group, 1 is preferably an arylene group, more preferably a phenylene group.

[0025] In the above general formula (1), 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. X 2 , X 3 and X 4 At least one of X is preferably a substituted amino group. 2 , X 3 and X 4 It is more preferable that two of them are substituted amino groups.

[0026] X 2 , X 3 and X 4 As the substituted amino group which can constitute the above, a group represented by the following general formula (2) is preferable.

[0027] [ka]

[0028] In the above general formula (2), R 1 and R 2 may or may not be bonded to each other, R 1 and R 2 If they are not bonded to each other, R 1 and R 2each independently represents a hydrocarbyl group which may have a substituent or a trihydrocarbylsilyl group; R 1 and R 2 When and are bonded to each other, R 1 and R 2 represents a hydrocarbylene group which may contain nitrogen and / or oxygen atoms.

[0029] R 1 and R 2 Examples of the hydrocarbyl group that can constitute the above include chain alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, and -octyl groups; cyclic alkyl groups such as cyclopentyl and cyclohexyl groups; and aryl groups such as phenyl, benzyl, and naphthyl groups. Among these, chain alkyl groups are preferred, and methyl or ethyl groups are more preferred. R 1 and R 2 When the hydrocarbyl group that can constitute the above has a substituent, examples of the hydrocarbyl group include a hydrocarbyloxy group as a substituent. Examples of the hydrocarbyl group having a hydrocarbyloxy group as a substituent include alkoxyalkyl groups such as a methoxymethyl group, an ethoxymethyl group, and a methoxyethyl group; and aryloxyalkyl groups such as a phenoxymethyl group.

[0030] R 1 and R 2 Specific examples of the trihydrocarbylsilyl group that can constitute the above group include trialkylsilyl groups such as trimethylsilyl group, triethylsilyl group, and tert-butyldimethylsilyl group.

[0031] R 1 and R 2 When and are bonded to each other, R 1 and R 2Examples of the hydrocarbylene group that can constitute R include alkylene groups such as trimethylene, tetramethylene, pentamethylene, hexamethylene, heptamethylene, octamethylene, decamethylene, dodecamethylene, and 2,2,4-trimethylhexane-1,6-diyl groups; and alkene diyl groups such as pentan-2-ene-1,5-diyl groups. 1 and R 2 When the hydrocarbylene group that can constitute the above formula contains a nitrogen atom and / or an oxygen atom, examples of the hydrocarbylene 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. R 1 and R 2 is an alkyl group, or R 1 and R 2 and R are preferably bonded to each other to form an alkylene group. 1 and R 2 is more preferably an alkyl group, and R 1 and R 2 is more preferably a methyl group or an ethyl group.

[0032] In the above general formula (2), R 1 and R 2 When is a hydrocarbyl group, specific examples of the group represented by the above general formula (2) include dialkylamino groups such as dimethylamino group, diethylamino group, ethylmethylamino group, di-n-propylamino group, diisopropylamino group, di-n-butylamino group, diisobutylamino group, di-sec-butylamino group, and di-tert-butylamino group; diarylamino groups such as diphenylamino group; etc. Among these, dialkylamino groups are preferred, and dimethylamino group, diethylamino group, and di-n-butylamino group are more preferred.

[0033] In the above general formula (2), R 1 and R 2In the case where is a hydrocarbyl group having a hydrocarbyloxy group as a substituent, specific examples of the group represented by the above general formula (2) include di(alkoxyalkyl)amino groups such as di(methoxymethyl)amino and di(ethoxymethyl)amino.

[0034] In the above general formula (2), R 1 and R 2 When is a trihydrocarbylsilyl group, specific examples of the group represented by the above general formula (2) include trialkylsilyl group-containing amino groups such as a bis(trimethylsilyl)amino group, a bis(tert-butyldimethylsilyl)amino group, and an N-trimethylsilyl-N-methylamino group.

[0035] In the above general formula (2), R 1 and R 2 and 1-(2-methylphenyl)-1-propanediyl)-1,2-diphenyl ...

[0036] In the above general formula (2), R 1 and R 2 and are bonded to each other to form a hydrocarbylene group containing a nitrogen atom and / or an oxygen atom, specific examples of the group represented by the above general formula (2) include a 1-imidazolyl group, a 4,5-dihydro-1-imidazolyl group, and a morpholino group.

[0037] As the group represented by the above general formula (2), a dialkylamino group or a 1-alkyleneimino group is preferable, a dialkylamino group is more preferable, and a dimethylamino group, a diethylamino group or a di-n-butylamino group is even more preferable.

[0038] In the above general formula (1), X 2 , X3 and X 4 Examples of hydrocarbyloxy groups that can constitute the above formula include alkoxy groups such as methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, sec-butoxy, and tert-butoxy groups; aryloxy groups such as phenoxy and benzyloxy groups; and the like.

[0039] In the above general formula (1), X 2 , X 3 and X 4 Examples of hydrocarbyl groups that can constitute the above formula include alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, and tert-butyl groups; and aryl groups such as phenyl, 4-methyl-1-phenyl, and benzyl groups. X 2 , X 3 and X 4 When the hydrocarbyl group that can constitute the above has a substituent, examples of the substituent include hydrocarbyl groups having a hydrocarbyloxy group, such as alkoxyalkyl groups such as a methoxymethyl group, an ethoxymethyl group, and an ethoxyethyl group.

[0040] In the above general formula (1), X 1 is a chemical single bond, and X 2 , X 3 and X 4Specific examples of vinyl compounds containing a silicon atom-containing functional group represented by the above general formula (1) in the case where one of the above 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; [bis(trimethylsilyl)amino]dimethylvinylsilane, [bis(t-butyldimethylsilyl)amino]dimethylvinylsilane, [bis(trimethylsilyl)amino]diethylvinylsilane, and [bis(t-butyldimethylsilyl)amino]diethylvinylsilane; (dimethylamino)di(methoxymethyl)vinylsilane, (dimethylamino)di(methoxyethyl)vinylsilane, (dimethylamino)di(ethoxymethyl)vinylsilane, (dimethylamino)di(ethoxyethyl)vinylsilane, (diethylamino)di(methoxymethyl)vinylsilane, (diethylamino)di(methoxyethyl)vinylsilane, (diethylamino)di(ethoxymethyl)vinylsilane, (diethylamino)di(ethoxyethyl)vinylsilane and other (dialkylamino)di(alkoxyalkyl)vinylsilanes; pyrrolidinodimethylvinylsilane, piperidinodimethylvinylsilane, hexamethyleneiminodimethylvinylsilane, 4,5-dihydroimidazolyldimethylvinylsilane, morpholinodimethylvinylsilane and other cyclic aminodialkylvinylsilane compounds;

[0041] In the above general formula (1), X 1 is a hydrocarbylene group, and X 2 , X 3 and X 4Specific examples of vinyl compounds containing a silicon atom-containing functional group represented by the above general formula (1) in which one of the groups 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- and (dialkylamino)dialkylvinylphenylsilanes such as (dialkylamino)diethyl-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.

[0042] In the above general formula (1), X 1 is a chemical single bond, and X 2 , X 3 and X 4Specific examples of vinyl compounds containing a silicon atom-containing functional group represented by the above general formula (1) in the case where two of the above 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; bis[bis(trimethylsilyl)amino]methylvinylsilane, bis[bis(tert-butyldimethylsilyl)amino]methylvinylsilane, bis[bis(trimethylsilyl)amino]ethylvinylsilane, and bis[bis(tert-butyldimethylsilyl)amino]ethylvinylsilane. which bis[bis(trialkylsilyl)amino]alkylvinylsilanes; 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, and bis(dimethylamino)ethoxyethylvinylsilane; bis(cyclic amino)alkylvinylsilane compounds such as bis(pyrrolidino)methylvinylsilane, bis(piperidino)methylvinylsilane, bis(hexamethyleneimino)methylvinylsilane, bis(4,5-dihydroimidazolyl)methylvinylsilane, and bis(morpholino)methylvinylsilane; and the like.

[0043] In the above general formula (1), X 1 is a hydrocarbylene group, and X 2 , X 3 and X 4Specific examples of vinyl compounds containing a silicon atom-containing functional group represented by the above general formula (1) in the case where two of the above 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- and bis(dialkylamino)alkylvinylphenylsilanes such as bis(dimethylamino)ethyl-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.

[0044] In the above general formula (1), X 1 is a chemical single bond, and X 2 , X 3 and X 4 Specific examples of vinyl compounds containing a silicon atom-containing functional group represented by the above general formula (1) in the case where three of the above are substituted amino groups include tris(dialkylamino)vinylsilanes such as tris(dimethylamino)vinylsilane, tris(diethylamino)vinylsilane, tris(di-n-propylamino)vinylsilane, and tris(di-n-butylamino)vinylsilane.

[0045] In the above general formula (1), X 1 is a hydrocarbylene group, and X 2 , X 3 and X 4Specific examples of vinyl compounds containing a silicon atom-containing functional group represented by the above general formula (1) in the case where three of them are substituted amino groups include tris(dialkylamino)vinylphenylsilanes such as tris(dimethylamino)-4-vinylphenylsilane, tris(dimethylamino)-3-vinylphenylsilane, tris(diethylamino)-4-vinylphenylsilane, tris(diethylamino)-3-vinylphenylsilane, tris(di-n-propylamino)-4-vinylphenylsilane, tris(di-n-propylamino)-3-vinylphenylsilane, tris(di-n-butylamino)-4-vinylphenylsilane, and tris(di-n-butylamino)-3-vinylphenylsilane.

[0046] In the above general formula (1), X 1 is a chemical single bond, and X 2 , X 3 and X 4 Specific examples of vinyl compounds containing a silicon atom-containing functional group represented by the above general formula (1), in which none of the above groups is a substituted amino group, include trialkoxyvinylsilanes such as trimethoxyvinylsilane, triethoxyvinylsilane, and tripropoxyvinylsilane; dialkoxyalkylvinylsilanes such as methyldimethoxyvinylsilane and methyldiethoxyvinylsilane; dialkoxyarylvinylsilanes such as di(tert-pentoxy)phenylvinylsilane and di(tert-butoxy)phenylvinylsilane; monoalkoxydialkylvinylsilanes such as dimethylmethoxyvinylsilane; monoalkoxydiarylvinylsilanes such as tert-butoxydiphenylvinylsilane and tert-pentoxydiphenylvinylsilane; monoalkoxyalkylarylvinylsilanes such as tert-butoxymethylphenylvinylsilane and tert-butoxyethylphenylvinylsilane; and substituted alkoxyvinylsilane compounds such as tris(β-methoxyethoxy)vinylsilane.

[0047] Among the compounds represented by the above general formula (1), X 1 is preferably a chemical single bond, and X1 is a chemical single bond and X 2 , X 3 and X 4 Among these, a compound in which two are substituted amino groups is more preferred, and X 1 is a chemical single bond and X 2 , X 3 and X 4 Among these, a compound in which two of the groups are dialkylamino groups is particularly preferred.

[0048] Among the compounds represented by the above general formula (1), bis(dimethylamino)methylvinylsilane, bis(diethylamino)methylvinylsilane, and bis(di-n-butylamino)methylvinylsilane are preferred, with bis(diethylamino)methylvinylsilane being particularly preferred.

[0049] 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; pyrrolidinoethylstyrene, among which pyrrolidinoethylstyrene is preferred.Note that pyrrolidinoethylstyrene may be any of ortho, meta, and para, but meta and para are preferred, and a mixture of meta and para is more preferred.

[0050] In addition, when the compound represented by the above 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.

[0051] [ka]

[0052] In the above general formula (3), X 5 represents a chemical single bond or a hydrocarbylene group, and 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.

[0053] In the unit represented by the general formula (3), X 5 is X in the compound represented by the above general formula (1). 1 In the unit represented by the general formula (3), X 6 , X 7 and X 8 is X in the compound represented by the above general formula (1). 2 , X 3 and X 4 Therefore, in the unit represented by the above general formula (3), X 5 , X 6 , X 7 and X 8 is X in the compound represented by the above general formula (1). 1 , X 2 , X 3 and X 4 In addition, the compound represented by the above general formula (1) may be represented by the formula 2 , X 3 and X 4 In the case where at least one of X is a substituted amino group or a hydrocarbyloxy group, the substituted amino group or the hydrocarbyloxy group can be hydrolyzed at any step and timing to obtain X 2 , X 3 and X 4 At least one of the groups may be a hydroxyl group.

[0054] <Content> The content of the vinyl compound unit containing a functional group capable of interacting with silica in the polymer block (A) is not particularly limited, and the content relative to the total monomer units constituting the polymer block (A) is preferably adjusted to be in the range of 0.01 to 20 mass%, more preferably in the range of 0.02 to 2 mass%, and particularly preferably in the range of 0.05 to 1 mass%. By setting the content of the vinyl compound unit containing a functional group capable of interacting with silica in the above range, the effect of suppressing adhesion to the roll, and the effect of improving low heat generation and handling stability can be made more remarkable.

[0055] <Other monomer units> The polymer block (A) may also contain other monomer units other than the isoprene monomer unit, the aromatic vinyl monomer unit, and the vinyl compound unit containing a functional group capable of interacting with silica. Examples of other compounds constituting such other monomer units include linear olefin compounds such as ethylene, propylene, and 1-butene; cyclic olefin compounds such as cyclopentene and 2-norbornene; conjugated diene compounds other than isoprene such as 1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 2-chloro-1,3-butadiene, 1,3-pentadiene, and 1,3-hexadiene; non-conjugated diene compounds such as 1,5-hexadiene, 1,6-heptadiene, 1,7-octadiene, dicyclopentadiene, and 5-ethylidene-2-norbornene. The content of other monomer units in the 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.

[0056] [Weight average molecular weight (Mw)] 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 small, the effect of suppressing adhesion to the roll, and the effect of improving the low heat build-up and steering stability cannot be obtained. On the other hand, if the weight average molecular weight (Mw) of the polymer block (A) is too large, the low heat build-up of the obtained cross-linked rubber product decreases.

[0057] [Mw / Mn] The molecular weight distribution of the polymer block (A), which is expressed by the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn), is preferably 1.0 to 1.5, and more preferably 1.0 to 1.3. When the molecular weight distribution value (Mw / Mn) of the polymer block (A) is within the above range, the production of the conjugated diene rubber becomes easier. In this specification, the weight average molecular weight (Mw) and number average molecular weight (Mn) can be determined as polystyrene-equivalent values ​​by gel permeation chromatography (GPC) measurement.

[0058] [Polymer block (B)] The polymer block (B) is not particularly limited as long as it contains 1,3-butadiene monomer units (preferably contains 1,3-butadiene monomer units as the main component), and may be composed of 1,3-butadiene monomer units only, or may be composed of 1,3-butadiene monomer units and monomer units other than 1,3-butadiene monomer units. In this case, a suitable example of the monomer units other than 1,3-butadiene monomer units is an aromatic vinyl monomer unit, and the polymer block (B) of the present invention preferably contains aromatic vinyl monomer units in addition to 1,3-butadiene monomer units.

[0059] [1,3-butadiene monomer unit content] The content of the 1,3-butadiene monomer unit in the polymer block (B) (1,3-butadiene monomer unit content) is preferably 55 to 65 mass%, more preferably 55 to 63 mass%, and further preferably 55 to 60 mass%. By setting the 1,3-butadiene monomer unit content in the polymer block (B) within the above range, the production of the conjugated diene rubber becomes easier.

[0060] [Vinyl bond content in 1,3-butadiene monomer unit] The vinyl bond content in the 1,3-butadiene monomer unit in the polymer block (B) is preferably 10 to 50 mass%, more preferably 15 to 40 mass%, and particularly preferably 20 to 35 mass%. By setting the vinyl bond content in the 1,3-butadiene monomer unit in the polymer block (B) within the above range, the obtained cross-linked rubber product can be made to have excellent low heat build-up properties.

[0061] [Aromatic vinyl compounds for forming aromatic vinyl monomer units] As the aromatic vinyl compound for forming the aromatic vinyl monomer unit, those exemplified in the description of the polymer block (A) can be used, and among the aromatic vinyl compounds, styrene is preferred. The aromatic vinyl monomer unit content of the polymer block (B) is preferably 35 to 45 mass%, more preferably 40 to 45 mass%.

[0062] [Vinyl compound units containing functional groups capable of interacting with silica] The specific conjugated diene rubber contains a vinyl compound unit containing a functional group capable of interacting with silica in at least one of the above-mentioned polymer block (A) and polymer block (B), but the specific conjugated diene rubber may have such a vinyl compound unit containing a functional group capable of interacting with silica in only the polymer block (A), only the polymer block (B), or both the polymer block (A) and the polymer block (B). For the reason that the effect of the present invention is more excellent, it is preferable that at least the polymer block (B) contains a vinyl compound unit containing a functional group capable of interacting with silica.

[0063] <Vinyl compound containing a functional group capable of interacting with silica> As the vinyl compound having a functional group capable of interacting with silica for forming the vinyl compound unit having a functional group capable of interacting with silica, those exemplified in the above description of the polymer block (A) can be used, and those exemplified as preferred compounds in the above description of the polymer block (A) can be suitably used.

[0064] <Content> The content of the vinyl compound units containing a functional group capable of interacting with silica in the polymer block (B) is not particularly limited, and it is preferable to adjust the content relative to the total monomer units constituting the polymer block (B) to be preferably in the range of 0.01 to 20 mass%, more preferably in the range of 0.02 to 2 mass%, and particularly preferably in the range of 0.05 to 1 mass%.

[0065] <Other monomer units> The polymer block (B) may contain other monomer units other than the 1,3-butadiene monomer unit, the aromatic vinyl monomer unit, and the vinyl compound unit containing a functional group capable of interacting with silica. As the other compounds constituting such other monomer units, isoprene can be used in addition to the compounds exemplified in the above-mentioned polymer block (A) (excluding 1,3-butadiene). The content of the other monomer units in the 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.

[0066] [Mass ratio of polymer block (A) to polymer block (B)] 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 polymer blocks (B) are present, the mass ratio is based on the total mass of each of them) (mass of polymer block (A)) / (mass of polymer block (B)) is preferably 0.001 to 0.2, more preferably 0.005 to 0.1, and particularly preferably 0.01 to 0.05. By setting the mass ratio of the polymer block (A) to the polymer block (B) within the above range, the obtained cross-linked rubber product can have a good balance between wet grip properties and low heat build-up.

[0067] [Content of each unit]

[0068] [1,3-butadiene monomer unit content] 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, and is preferably 55 to 65 mass%, more preferably 55 to 63 mass%, and further preferably 55 to 60 mass%, because the effects of the present invention are more excellent. Here, the 1,3-butadiene monomer unit content in the entire specific conjugated diene rubber refers to the content of 1,3-butadiene monomer units relative to the total monomer units constituting the specific conjugated diene rubber.

[0069] [Aromatic vinyl monomer unit content] As described above, the content of aromatic vinyl monomer units in the entire specific conjugated diene rubber (aromatic vinyl monomer unit content) is 30 to 45 mass %. Here, the aromatic vinyl monomer unit content in the entire specific conjugated diene rubber refers to the content of aromatic vinyl monomer units relative to the total monomer units constituting the specific conjugated diene rubber. The aromatic vinyl monomer unit content in the entire specific conjugated diene rubber is preferably 35 to 45 mass %, and more preferably 40 to 45 mass %, because the effects of the present invention are more excellent.

[0070] [Content of vinyl compound units containing functional groups capable of interacting with silica] The content of the units of the vinyl compound containing a functional group capable of interacting with silica in the entire specific conjugated diene rubber (for example, the content of bis(diethylamino)methylvinylsilane monomer units) is not particularly limited, but is preferably 0.01 to 20 mass%, more preferably 0.02 to 2 mass%, and even more preferably 0.05 to 1 mass%, because the effects of the present invention are more excellent.

[0071] [Vinyl bond content] The vinyl bond content of the conjugated diene monomer units (e.g., isoprene monomer units and 1,3-butadiene monomer units) in the entire specific conjugated diene rubber (hereinafter also simply referred to as "vinyl bond content of the entire specific conjugated diene rubber") is preferably 1 to 90 mass%, more preferably 3 to 85 mass%, and particularly preferably 5 to 80 mass%. Among them, for reasons of better effects of the present invention, it is preferably 10 to 50 mass%, more preferably 20 to 40 mass%, and even more preferably 20 to 35 mass%. By setting the vinyl bond content of the entire specific conjugated diene rubber within the above range, the obtained rubber cross-linked product can be made to have better low heat build-up properties.

[0072] [Modified structure with siloxane compound] As described above, the specific conjugated diene rubber has a modified structure by a siloxane compound at at least one end. The modified structure by the siloxane compound may be introduced via a modified structure by another modifier.

[0073] [Preferred embodiment] The siloxane compound is not particularly limited as long as it has a siloxane structure (-Si-O-) as the main chain, but is preferably an organosiloxane having an organic group on the side chain, and more preferably a polyorganosiloxane represented by the following general formula (4).

[0074] [ka]

[0075] 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. X 9 and X 12 is any group selected from the group consisting of an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, and an epoxy group-containing group having 4 to 12 carbon atoms, which may be the same or different. 10 is an alkoxy group having 1 to 5 carbon atoms or a group containing an epoxy group and having 4 to 12 carbon atoms; 10 When there are multiple X's, they may be the same or different. 11 is a group containing 2 to 20 repeating alkylene glycol units, X 11 When there are a plurality of m, they may be the same or different. 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.

[0076] In the polyorganosiloxane represented by the above general formula (4), R3 ~R 10 , X 9 and X 12 Examples of the alkyl group having 1 to 6 carbon atoms that can constitute the above include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, a butyl group, a pentyl group, a hexyl group, and a cyclohexyl group. Examples of the aryl group having 6 to 12 carbon atoms include a phenyl group and a methylphenyl group. Among these, from the viewpoint of ease of production of the polyorganosiloxane itself, a methyl group and an ethyl group are preferred.

[0077] In the polyorganosiloxane represented by the general formula (4), X 9 , X 10 and X 12 Examples of the alkoxy group having 1 to 5 carbon atoms that can constitute the above include a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, and a butoxy group. Among these, from the viewpoint of ease of production of the polyorganosiloxane itself, a methoxy group and an ethoxy group are preferred.

[0078] Furthermore, in the polyorganosiloxane represented by the above general formula (4), X 9 , X 10 and X 12 Examples of the epoxy group-containing group having 4 to 12 carbon atoms that can constitute the above formula include groups represented by the following general formula (5).

[0079] -Z 1 -Z 2 -E (5)

[0080] 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 an epoxy group.

[0081] The group represented by the above general formula (5) is Z 2 is preferably an oxygen atom, and Z 2is an oxygen atom and E is a glycidyl group, 1 is an alkylene group having 1 to 3 carbon atoms, and Z 2 It is particularly preferred that R is an oxygen atom and E is a glycidyl group.

[0082] In the polyorganosiloxane represented by the general formula (4), X 9 and X 12 Among the above, X is preferably a group containing an epoxy group and having 4 to 12 carbon atoms, or an alkyl group having 1 to 6 carbon atoms. 10 Among the above, an epoxy group-containing group having 4 to 12 carbon atoms is preferable. 9 and X 12 is an alkyl group having 1 to 6 carbon atoms, and X 10 It is more preferable that the group is an epoxy group-containing group having 4 to 12 carbon atoms.

[0083] In the polyorganosiloxane represented by the general formula (4), X 11 That is, as a group containing 2 to 20 repeating units of alkylene glycol, a group represented by the following general formula (6) is preferred.

[0084] [ka]

[0085] In the above general formula (6), t is an integer of 2 to 20, and X 13 is an alkylene group or alkylarylene group having 2 to 10 carbon atoms, R 11 is a hydrogen atom or a methyl group, and X 14 is an alkoxy group or an aryloxy group having 1 to 10 carbon atoms. Among these, t is an integer of 2 to 8, and X 13 is an alkylene group having 3 carbon atoms, and R 11 is a hydrogen atom and X 14 is preferably a methoxy group.

[0086] 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 becomes easier to produce, and the viscosity does not become too high, making it easier to handle.

[0087] In the polyorganosiloxane represented by the general formula (4), n is an integer of 0 to 200, preferably an integer of 0 to 150, more preferably an integer of 0 to 120. k is an integer of 0 to 200, preferably an integer of 0 to 150, more preferably an integer of 0 to 130. The total number of m, n, and k is 1 or more, preferably 3 to 400, more preferably 20 to 300, and particularly preferably 30 to 250. When the total number of m, n, and k is 1 or more, the reaction between the polyorganosiloxane represented by the general formula (4) and the conjugated diene polymer chain having an active terminal easily proceeds, and when the total number of m, n, and k is 400 or less, the polyorganosiloxane represented by the general formula (4) itself is easily produced, and the viscosity does not become too high, making it easy to handle.

[0088] [Weight average molecular weight (Mw)] The weight average molecular weight (Mw) of the entire specific conjugated diene rubber 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 making the weight average molecular weight of the entire specific conjugated diene rubber within the above range, it becomes easy to compound silica into a rubber composition containing such a conjugated diene rubber, and the processability of the rubber composition can be further improved, and further, the low heat build-up property of the obtained rubber cross-linked product can be further improved.

[0089] [Mw / Mn] The overall 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 entire specific conjugated diene rubber, is preferably 1.1 to 3.0, more preferably 1.2 to 2.5, and particularly preferably 1.2 to 2.2. By setting the molecular weight distribution (Mw / Mn) within the above range, the low heat build-up property of the obtained cross-linked rubber can be further improved.

[0090] [Mooney Viscosity] In addition, the Mooney viscosity (ML 1+4 , 100° C.) is preferably 20 to 100, more preferably 30 to 90, and particularly preferably 35 to 80. When the conjugated diene rubber is used as the oil-extended rubber, it is preferable that the Mooney viscosity of the oil-extended rubber is within the above range.

[0091] [Glass transition temperature (Tg)] The glass transition temperature (Tg) of the specific conjugated diene rubber is not particularly limited, but is preferably 20 to −110° C., and 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 aromatic vinyl monomer unit content in the conjugated diene rubber and the vinyl bond content in the conjugated diene monomer unit portion.

[0092] [Manufacturing method] The specific conjugated diene rubber can be produced, for example, by a process (step A) of polymerizing an isoprene-containing monomer (a) in an inert solvent with a polymerization initiator to form a polymer block (A) having an active terminal; a step (step B) of mixing the obtained polymer block (A) having an active end with a monomer (b) containing 1,3-butadiene to continue the polymerization reaction, thereby obtaining a conjugated diene-based polymer chain having an active end, which comprises the polymer block (A) and the polymer block (B); The polysiloxane can be produced through a step (step C) of reacting the active end of the obtained conjugated diene polymer chain having an active end with a siloxane compound.

[0093] [Step of forming polymer block (A) having active terminal (Step A)] <Monomer (a)> The monomer (a) for forming the polymer block (A) may contain isoprene, and a monomer corresponding to the monomer composition of the polymer block (A) to be formed (the monomer composition described above) 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. When the polymer block (A) has, in addition to the isoprene monomer units and aromatic vinyl monomer units, a vinyl compound unit containing a functional group capable of interacting with silica, the monomer (a) may contain, in addition to isoprene and an aromatic vinyl compound, a vinyl compound containing a functional group capable of interacting with silica.

[0094] <Inert Solvent> The inert solvent used in the polymerization of the monomer (a) containing isoprene to form the polymer block (A) is not particularly limited as long as it is one that is usually used in solution polymerization and does not inhibit the polymerization reaction. Specific examples of the inert solvent include linear or branched aliphatic hydrocarbons such as propane, n-butane, isobutane, n-pentane, isopentane, n-hexane, propene, 1-butene, isobutene, trans-2-butene, cis-2-butene, 1-pentene, 2-pentene, 1-hexene, 2-hexene, and n-heptane; alicyclic hydrocarbons such as cyclopentane and cyclohexane; aromatic hydrocarbons such as benzene, ethylbenzene, toluene, and xylene; and ether compounds such as tetrahydrofuran and diethyl ether. 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, for example, an amount that provides a monomer concentration of 1 to 80% by mass, and preferably an amount that provides a monomer concentration of 5 to 50% by mass.

[0095] <Polymerization initiator> 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 give a polymer chain having an active terminal. Specific examples of the polymerization initiator include polymerization initiators using an organic alkali metal compound, an organic alkaline earth metal compound, and a lanthanum series metal compound as a main catalyst. Examples of the organic alkali metal compound include organic monolithium compounds such as n-butyl lithium, sec-butyl lithium, t-butyl lithium, hexyl lithium, phenyl lithium ethyl lithium, n-propyl lithium, isopropyl lithium, tert-octyl lithium, n-decyl lithium, 2-naphthyl lithium, 2-butylphenyl lithium, 4-phenylbutyl lithium, hexyl lithium, cyclopentyl lithium, a reaction product of diisopropenylbenzene with butyl lithium, and stilbene lithium; dilithium compounds such as diisopropenylbenzene, 1,4-dimethylphenyl lithium, and 1,4-dimethylphenyl lithium; ... -dilithiobutane, 1,4-dilithio-2-ethylcyclohexane, 1,3,5-trilithiobenzene, 1,3,5-tris(lithiomethyl)benzene, organic polyvalent lithium compounds such as a reaction product of sec-butyllithium and diisopropenylbenzene, a reaction product of n-butyllithium and 1,3-butadiene and divinylbenzene, and a reaction product of n-butyllithium and a polyacetylene compound; organic sodium compounds such as sodium naphthalene; organic potassium compounds such as potassium naphthalene; organic rubidium compounds; organic cesium compounds, etc. Other examples include alkoxides, sulfonates, carbonates, amides, etc. of lithium, sodium, potassium, etc. Also, other organometallic compounds may be used in combination. Furthermore, known organoalkali metal compounds disclosed in U.S. Pat. No. 5,708,092, British Patent No. 2,241,239, U.S. Pat. No. 5,527,753, etc. may also be used.

[0096] Examples of organic alkaline earth metal compounds include di-n-butyl magnesium, di-n-hexyl magnesium, diethoxy calcium, calcium distearate, di-t-butoxy strontium, diethoxy barium, diisopropoxy barium, diethylmercapto barium, di-t-butoxy barium, diphenoxy barium, diethylamino barium, barium distearate, diketyl barium, etc. Examples of polymerization initiators using a lanthanum series metal compound as a main catalyst include polymerization initiators using a lanthanum series metal salt consisting of a lanthanum series metal such as lanthanum, cerium, praseodymium, neodymium, samarium, gadolinium, etc., a carboxylic acid, and a phosphorus-containing organic acid, etc., as a main catalyst, and a co-catalyst such as an alkyl aluminum compound, an organoaluminum hydride compound, an organoaluminum halide compound, etc. Among these polymerization initiators, organic monolithium compounds and organic polyvalent lithium compounds are preferably used, organic monolithium compounds are more preferably used, and n-butyllithium is particularly preferably used from the viewpoint of industrial availability and ease of control of polymerization reaction.The organic alkali metal compound may be reacted in advance with a secondary amine such as dibutylamine, dihexylamine, dibenzylamine, pyrrolidine, piperidine, hexamethyleneimine, and heptamethyleneimine to be used as an organic alkali metal amide compound.These polymerization initiators may be used alone or in combination of two or more. The organic alkali metal amide compound is not particularly limited, but examples thereof include lithium hexamethylene imide, lithium pyrrolidide, lithium piperidide, lithium heptamethylene imide, lithium dodecamethylene imide, lithium dimethylamide, lithium diethylamide, lithium dibutylamide, lithium dipropylamide, lithium diheptylamide, lithium dihexylamide, lithium dioctylamide, lithium di-2-ethylhexylamide, lithium didecylamide, lithium-N-methylpiperazide, lithium ethylpropylamide, lithium ethylbutylamide, lithium ethylbenzylamide, and lithium methylphenethylamide.

[0097] (Amount used) The amount of the polymerization initiator used may be determined depending on the target molecular weight, but is preferably in the range of 4 to 250 mmol, more preferably 6 to 200 mmol, and particularly preferably 10 to 70 mmol, per 100 g of the isoprene-containing monomer (a).

[0098] <Polymerization temperature when polymerizing monomer (a)> The polymerization temperature during polymerization of the isoprene-containing monomer (a) is preferably in the range of -80 to +150°C, more preferably 0 to 100°C, and further preferably 20 to 90°C. Any polymerization mode, such as a batch mode or a continuous mode, can be adopted. In addition, when the polymer block (A) is made into a copolymer chain, various bonding modes, such as a block type, a tapered type, and a random type, can be adopted.

[0099] <Polar compounds> In addition, when polymerizing the monomer (a), it is preferable to add a polar compound to the inert solvent in order to adjust the vinyl bond content in the isoprene monomer unit in the polymer block (A). Examples of the polar compound include ether compounds such as dibutyl ether, tetrahydrofuran, and 2,2-di(tetrahydrofuryl)propane; tertiary amines such as tetramethylethylenediamine; alkali metal alkoxides; and phosphine compounds. Among 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 may be determined according to the desired vinyl bond content, and is preferably 0.01 to 30 mol, and more preferably 0.05 to 10 mol, relative to 1 mol of the polymerization initiator. When the amount of the polar compound used is within the above range, it is easy to adjust the vinyl bond content in the isoprene monomer unit, and furthermore, problems due to deactivation of the polymerization initiator are unlikely 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.

[0100] [Step B: Obtaining a Conjugated Diene Polymer Chain Having an Active End] Next, polymer block (A) having an active end obtained by polymerizing monomer (a) containing isoprene is mixed with monomer (b) containing 1,3-butadiene to continue the polymerization reaction, thereby forming polymer block (B) in a continuous state with polymer block (A), thereby obtaining a conjugated diene polymer chain having an active end, which comprises polymer block (A) and polymer block (B). Note that the formed polymer block (B) has an active end, while the active end disappears from polymer block (A).

[0101] <Monomer (b)> The monomer (b) for forming the polymer block (B) may contain 1,3-butadiene, and a monomer corresponding to the monomer composition (above-mentioned monomer composition) of the polymer block (B) to be formed may 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) may contain 1,3-butadiene and an aromatic vinyl compound. When the polymer block (B) has, in addition to the 1,3-butadiene monomer units and aromatic vinyl monomer units, a vinyl compound unit containing a functional group capable of interacting with silica, the monomer (b) may contain, in addition to the 1,3-butadiene monomer units and aromatic vinyl monomer units, a vinyl compound containing a functional group capable of interacting with silica.

[0102] (Vinyl compounds containing functional groups capable of interacting with silica) The specific conjugated diene rubber contains a vinyl compound unit containing a functional group capable of interacting with silica in at least one of the above-mentioned polymer block (A) and polymer block (B). Therefore, in the above-mentioned production method, 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) may contain a vinyl compound containing a functional group capable of interacting with silica.

[0103] <Inert Solvent> The inert solvent used in the polymerization of the 1,3-butadiene-containing monomer (b) to form the polymer block (B) is not particularly limited, and the same inert solvents as those described above can be used.

[0104] <Amount of polymer block (A) having active terminal> The amount of the polymer block (A) having an active end used in forming the polymer block (B) may be determined depending on 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.

[0105] <Method of mixing polymer block (A) and monomer (b) containing 1,3-butadiene> The method of mixing the polymer block (A) and the monomer (b) containing 1,3-butadiene is not particularly limited, and the polymer block (A) having an active end may be added to a solution of the monomer (b) containing 1,3-butadiene, or the monomer (b) containing 1,3-butadiene may be added to a solution of the polymer block (A) having an active end. From the viewpoint of controlling the polymerization, the method of adding the polymer block (A) having an active end to a solution of the monomer (b) containing 1,3-butadiene is preferred.

[0106] <Polymerization temperature, polymerization mode> The polymerization temperature when polymerizing the monomer (b) containing 1,3-butadiene is preferably in the range of -80 to +150°C, more preferably 0 to 100°C, and further preferably 20 to 90°C. As the polymerization mode, any mode such as a batch mode or a continuous mode can be adopted. When the polymer block (B) is a copolymer chain, the batch mode is preferred in that it is easy to control the randomness of the bonds.

[0107] <Bonding Mode> When the polymer block (B) is a copolymer chain, the bonding pattern of each monomer may be various bonding patterns such as block, tapered, and random. Among these, the random bonding pattern is preferable. By making the bonding pattern random, the low heat build-up property of the obtained cross-linked rubber can be further improved.

[0108] <Polar compounds> In addition, in order to adjust the vinyl bond content in the 1,3-butadiene monomer unit in the polymer block (B), it is preferable to add a polar compound to the inert solvent during polymerization, as in the case of adjusting the vinyl bond content in the isoprene monomer unit in the polymer block (A). However, if a polar compound is added to the inert solvent in an amount sufficient to adjust the vinyl bond content in the 1,3-butadiene monomer unit in the polymer block (B) during preparation of the polymer block (A), it is not necessary to add a new polar compound. As the polar compound used to adjust the vinyl bond content, the same polar compounds as those described above can be used. The amount of the polar compound used may be determined according to the desired vinyl bond content, and may be adjusted within a range of preferably 0.01 to 100 mol, more preferably 0.1 to 30 mol, relative to 1 mol of the polymerization initiator used in the first 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 unlikely to occur.

[0109] <Conjugated diene polymer chain having active terminal> In this way, a conjugated diene polymer chain having an active end, which has a polymer block (A) and a polymer block (B), can be obtained. In the present invention, the conjugated diene polymer chain having an active end is preferably composed of a polymer block (A)-polymer block (B) from the viewpoint of productivity, and the end of the polymer block (B) is preferably an active end, but it may have a plurality of polymer blocks (A) or may have other polymer blocks. For example, a conjugated diene polymer chain having an active end, such as a polymer block (A)-polymer block (B)-polymer block (A), may be mentioned. In this case, an active end is formed at the end of the polymer block (A) formed following the polymer block (B). When forming the polymer block (A) on the active end 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)).

[0110] [Step C: Reacting a Siloxane Compound with an Active End of a Conjugated Diene Polymer Chain Having an Active End] Next, a siloxane compound is reacted with the active end of the resulting conjugated diene polymer chain having an active end, thereby introducing a modified structure by the siloxane compound into the end of the conjugated diene polymer chain.

[0111] <Amount of siloxane compound used> The amount of the siloxane compound used when reacting a conjugated diene polymer chain having an active terminal with a siloxane compound is preferably 0.01 to 10 moles, more preferably 0.1 to 5 moles, per 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 siloxane compound used is within the above range, the low heat build-up property of the obtained cross-linked rubber can be further improved. It is preferable to set the number of moles per siloxane structure (-Si-O-) within the above range.

[0112] <Method of reacting a siloxane compound with a conjugated diene polymer chain having an active end> The method of reacting the siloxane compound with the conjugated diene polymer chain having an active terminal is not particularly limited, but includes a method of mixing them in a solvent in which each of them can be dissolved. The solvent used in this case can be any of those exemplified as the inert solvent used in the polymerization reaction described above. In addition, in this case, a method of adding the siloxane compound to the polymerization solution used in the polymerization to obtain the conjugated diene polymer chain having an active terminal is simple and preferable. Furthermore, in this case, it is preferable to dissolve the siloxane compound in an inert solvent and add it to the polymerization system, and the solution concentration is preferably in the range of 1 to 50 mass%. The reaction temperature is not particularly limited, but is usually 0 to 120°C, and the reaction time is not particularly limited, but is usually 1 minute to 1 hour.

[0113] <When to add siloxane compounds> The timing of adding the siloxane compound to the solution containing the conjugated diene polymer chain having an active terminal is not particularly limited, but it is desirable to add the siloxane compound to the solution when the polymerization reaction is not completed and the solution containing the conjugated diene polymer chain having an active terminal also contains a monomer, more specifically, when the solution containing the conjugated diene polymer chain having an active terminal contains 100 ppm or more, more preferably 300 to 50,000 ppm of a monomer. By adding the siloxane compound in this manner, it is possible to suppress side reactions between the conjugated diene polymer chain having an active terminal and impurities contained in the polymerization system, and to control the reaction well. In addition, in order to further improve the processability of the obtained rubber composition, a siloxane compound may be added to the solution containing the conjugated diene polymer chain having an active terminal, reacted, and then further mixed with an organometallic compound, which can improve the processability of the obtained rubber composition (compound Mooney can be kept low). In addition, in this case, after mixing the organometallic compound, the siloxane compound may be further added and reacted.As the organometallic compound, n-butyl lithium, sec-butyl lithium, t-butyl lithium, hexyl lithium, phenyl lithium, ethyl lithium, n-propyl lithium, isopropyl lithium, tert-octyl lithium, n-decyl lithium, 2-naphthyl lithium, 2-butylphenyl lithium, 4-phenylbutyl lithium, hexyl lithium, cyclopentyl lithium, the reaction product of diisopropenylbenzene and butyl lithium, stilbene lithium and other organic monolithium compounds may be mentioned.

[0114] In this way, by reacting a siloxane compound with the active end of a conjugated diene polymer chain having an active end, a modified structure 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 by the siloxane compound introduced into the polymer chain end, but may also include an unmodified conjugated diene polymer chain that has not been modified by the siloxane compound.

[0115] As the conjugated diene polymer chain having an active end, a polymer block (A) having an active end (for example, a polymer chain represented by polymer block (A)-polymer block (B)-polymer block (A)) may be used, and a siloxane compound may be reacted with the end of the polymer block (A) to introduce a modified structure with the siloxane compound at the end of the polymer block (A). Alternatively, a polymer block (B) having an active end (for example, a polymer chain represented by polymer block (A)-polymer block (B)) may be used, and a siloxane compound may be reacted with the end of the polymer block (B) to introduce a modified structure with the siloxane compound at the end of the polymer block (B). From the viewpoint of further enhancing the low heat generation property of the obtained cross-linked rubber product, it is preferable to introduce a modified structure with the siloxane compound at the end of the polymer block (B) by reacting a siloxane compound with the end of the polymer block (B).

[0116] [Coupling] Furthermore, before the conjugated diene polymer chain having an active end is reacted with a siloxane compound, or after the reaction with a siloxane compound, when the conjugated diene polymer chain having an active end remains, a part of the active end of the conjugated diene polymer chain having an active end may be coupled by adding a coupling agent or the like that has been conventionally used to the polymerization system within a range that does not impair the effects of the present invention.

[0117] [Deactivation] After reacting the siloxane compound with the conjugated diene polymer chain having an active terminal, it is preferable to add a polymerization terminator such as an alcohol such as methanol, ethanol, or isopropanol, or water to deactivate the unreacted active terminal.

[0118] [Additives] After deactivating the active end of the conjugated diene polymer chain, if desired, an antiaging agent such as a phenol-based stabilizer, a phosphorus-based stabilizer, or a sulfur-based stabilizer, a crumbing agent, and a scale inhibitor are added to the reaction solution of the conjugated diene rubber having a modified structure at the end by a siloxane compound, and then the polymerization solvent is separated from the reaction solution by direct drying or steam stripping, and the solid conjugated diene rubber having a modified structure at the end by a siloxane compound is recovered. If desired, an extender oil may be blended to make the conjugated diene rubber into an oil-extended rubber. Examples of the extender oil include paraffin-based, aromatic-based, and naphthene-based petroleum-based softeners, vegetable-based softeners, and fatty acids. When a petroleum-based softener is used, it is preferable that the content of polycyclic aromatics extracted by the IP346 method (the test method of THE INSTITUTE 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.

[0119] [Content] As described above, the content of the specific conjugated diene rubber in the rubber component is 35% by mass or more. In particular, for reasons of superior effects of the present invention, the content is preferably 40 to 75% by mass, and more preferably 45 to 60% by mass.

[0120] [2] Specific copolymer rubber As described above, the rubber component contains the specific copolymer rubber. The specific copolymer rubber is an aromatic vinyl-conjugated diene copolymer rubber other than the specific conjugated diene rubber described above, the aromatic vinyl monomer unit content is 23 to 50 mass%, and the difference from the aromatic vinyl monomer unit content of the entire specific conjugated diene rubber is 10 mass% or less; It is an aromatic vinyl-conjugated diene copolymer rubber having a weight average molecular weight (Mw) of 800,000 or more.

[0121] Examples of aromatic vinyl-conjugated diene copolymer rubber include styrene-butadiene rubber (SBR), styrene-isoprene copolymer rubber, etc. Among these, SBR is preferred because it provides better effects of the present invention.

[0122] [Aromatic vinyl monomer unit content] The content of the aromatic vinyl monomer unit in the specific copolymer rubber (aromatic vinyl monomer unit content) is 23 to 50 mass %, and in particular, for reasons of superior effect of the present invention, it is preferably 30 to 50 mass %, and more preferably 35 mass % or more and less than 40 mass %.

[0123] Moreover, the difference between the aromatic vinyl monomer unit content in the specific copolymer and the aromatic vinyl monomer unit content in the entire specific conjugated diene rubber described above is 10% by mass or less. Here, the above "difference is 10 mass% or less" means that, when the aromatic vinyl monomer unit content of the entire specific conjugated diene rubber is X [mass%] and the aromatic vinyl monomer unit content of the specific copolymer rubber is Y [mass%], |XY|≦10 is satisfied.

[0124] [Conjugated diene monomer unit content] The content of the conjugated diene monomer unit in the specific copolymer rubber is not particularly limited, but is preferably 50 to 77% by mass, and more preferably 60 to 70% by mass, for reasons of superior effect of the present invention.

[0125] [Vinyl bond content] The vinyl bond content in the conjugated diene monomer units (for example, isoprene monomer units and 1,3-butadiene monomer units) in the specific copolymer rubber is not particularly limited, but in order to obtain better effects of the present invention, it is preferably 10 to 90 mass%, more preferably 20 to 80 mass%, even more preferably 30 to 70 mass%, and particularly preferably more than 35 mass% and 50 mass% or less.

[0126] [Weight average molecular weight (Mw)] The weight average molecular weight (Mw) of the specific polymer rubber is 800,000 or more. In particular, it is preferably more than 1,000,000 because the effects of the present invention are more excellent. The upper limit of Mw is not particularly limited, but it is preferably 10,000,000 or less, more preferably 5,000,000 or less, and even more preferably 2,000,000 or less because the effects of the present invention are more excellent.

[0127] [Glass transition temperature (Tg)] The glass transition temperature (Tg) of the specific copolymer rubber is not particularly limited, but is preferably 20 to −110° C., and more preferably 10 to −70° C. The glass transition temperature can be appropriately adjusted, for example, by adjusting the aromatic vinyl monomer unit content and the vinyl bond content in the conjugated diene monomer unit portion.

[0128] [Content] As described above, the content of the specific copolymer rubber in the rubber component is 25% by mass or more. In particular, for reasons of superior effects of the present invention, the content is preferably 25 to 65% by mass, more preferably 25 to 50% by mass, and even more preferably 25 to 40% by mass.

[0129] [3] Ratio of specific conjugated diene rubber to specific copolymer rubber The ratio of the content of the specific copolymer rubber to the content of the specific conjugated diene rubber in the rubber component (specific copolymer rubber / specific conjugated diene rubber) is preferably 30 to 90 mass%, more preferably 40 to 80 mass%, and even more preferably 50 to 70 mass%, for reasons of superior effects of the present invention.

[0130] [4] Other rubber components The rubber component may contain a rubber component (other rubber component) that does not fall under either the specific conjugated diene rubber or the specific copolymer rubber described above. Examples of such other rubber components include natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), styrene butadiene rubber (SBR) which does not fall under any of the above-mentioned specific conjugated diene rubbers and the above-mentioned specific copolymer rubbers, acrylonitrile-butadiene copolymer rubber (NBR), butyl rubber (IIR), halogenated butyl rubber (Br-IIR, Cl-IIR), chloroprene rubber (CR), etc. Among them, styrene butadiene rubber (SBR) which does not fall under any of the above-mentioned specific conjugated diene rubbers and the above-mentioned specific copolymer rubbers is preferable because the effects of the present invention are more excellent.

[0131] [Molecular weight] The weight average molecular weight (Mw) of the other rubber components is not particularly limited, but for the reason that the effects of the present invention are superior, it is preferably 50,000 to 5,000,000, more preferably 75,000 to 3,000,000, and further preferably 100,000 to 1,000,000.

[0132] [Content] The content of other rubber components in the rubber component is not particularly limited, but in order to obtain better effects of the present invention, the content is preferably 0 to 40 mass%, more preferably 10 to 40 mass%, and even more preferably 20 to 30 mass%.

[0133] [II] Silica 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 use in tires and the like can be used. Specific examples of silica include wet silica, dry silica, fumed silica, diatomaceous earth, etc. Among them, wet silica is preferred because it has better effects of the present invention. The silica may be used alone or in combination of two or more kinds.

[0134] [1] Content In the composition of the present invention, the content of silica is 50 to 150 parts by mass based on 100 parts by mass of the above-mentioned rubber component, and is preferably 60 to 100 parts by mass because the effect of the present invention is more excellent.

[0135] [2] Preferred embodiment The above silica has a CTAB (cetyltrimethylammonium bromide) adsorption specific surface area of ​​190 m because the effect of the present invention is more excellent. 2 It is preferable that the composition contains 20 parts by mass or more of silica (specific silica) having a silica content of 1000 mg / g or more. In particular, it is preferable that the composition contains 50 to 150 parts by mass of the specific silica, and more preferably 60 to 100 parts by mass of the specific silica, because the effect of the present invention is more excellent. The upper limit of the CTAB adsorption specific surface area of ​​the specific silica is not particularly limited, but in order to improve the effect of the present invention, it is preferable to use a specific silica having a CTAB adsorption specific surface area of ​​300 m 2 It is preferable that the molecular weight is not more than 1 / g. 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: Determination of specific surface area - CTAB adsorption method."

[0136] [III] Silane coupling agents 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. The hydrolyzable group is not particularly limited, and examples thereof include an alkoxy group, a phenoxy group, a carboxyl group, and an alkenyloxy group. Among them, an alkoxy group is preferable because the effects of the present invention are more excellent. When the hydrolyzable group is an alkoxy group, the number of carbon atoms of the alkoxy group is preferably 1 to 16, and more preferably 1 to 4, because the effects of the present invention are more excellent. Examples of the alkoxy group having 1 to 4 carbon atoms include a methoxy group, an ethoxy group, and a propoxy group.

[0137] The organic functional group is not particularly limited, but is preferably a group capable of forming a chemical bond with an organic compound, and examples thereof include an epoxy group, a vinyl group, an acryloyl group, a methacryloyl group, an amino group, a sulfide group, a mercapto group, a blocked mercapto group (protected mercapto group) (e.g., an octanoylthio group), and the like. Among these, a sulfide group (particularly a disulfide group or a tetrasulfide group), a mercapto group, and a blocked mercapto group are preferred because they provide better effects of the present invention.

[0138] 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, 3-octanoylthio-1-propyltriethoxysilane, and the like. One of these may be used alone, or two or more may be used in combination.

[0139] [1] Preferred embodiment The silane coupling agent is preferably a compound represented by the following general formula (S) because the effects of the present invention are more excellent. (C n H 2n+1 O)3-Si-C m H 2m -S-CO-C k H 2k+1 General formula (S) In 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).

[0140] [2] Content In the composition of the present invention, the content of the silane coupling agent is 3 to 30 mass% based on the content of the above-mentioned silica (the total content of all silicas including the specific silica). Among them, it is preferably 5 to 20 mass% because the effect of the present invention is more excellent.

[0141] In addition, 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, per 100 parts by mass of the rubber component, because the effects of the present invention are more excellent.

[0142] [IV] Optional component The composition of the present invention may contain components (optional components) other than the above-mentioned components, if necessary. Examples of such components include various additives commonly used in rubber compositions, such as 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, process oils, liquid polymers, thermosetting resins, vulcanizing agents (e.g., sulfur), and vulcanization accelerators.

[0143] [1] Carbon black The composition of the present invention preferably contains carbon black because the effects of the present invention are more excellent. 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 can be used. The nitrogen adsorption specific surface area (N2SA) of the carbon black is not particularly limited, but is preferably 50 to 200 m because the effect of the present invention is more excellent. 2 / g, and 70 to 150m 2 It is more preferable that the molecular weight is / g. Here, the nitrogen adsorption specific surface area (N2SA) is the amount of nitrogen adsorbed on the surface of carbon black measured according to JIS K6217-2:2001 "Part 2: Determination of specific surface area - Nitrogen adsorption method - Single point method."

[0144] [Content] In the composition of the present invention, the content of carbon black is not particularly limited, but in order to obtain better effects of the present invention, the content is preferably 1 to 100 parts by mass, and more preferably 2 to 10 parts by mass, per 100 parts by mass of the above-mentioned rubber component.

[0145] [2] Specific alkyltriethoxysilane The composition of the present invention preferably contains an alkyltriethoxysilane represented by the following general formula (I) (hereinafter, also referred to as a "specific alkyltriethoxysilane"), because this provides better effects of the present invention.

[0146] [ka]

[0147] In the above general formula (I), R 1 represents an alkyl group having 7 to 20 carbon atoms. Et represents an ethyl group. Specific examples of the alkyl group having 7 to 20 carbon atoms include a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, etc. Among these, an octyl group and a nonyl group are preferred because they provide better effects of the present invention.

[0148] [Content] In the composition of the present invention, the content of the specific alkyltriethoxysilane is not particularly limited, but because the effects of the present invention are more excellent, it is preferably 2.0 to 15.0 mass% relative to the above-mentioned silica content (the total content of all silicas including the specific silica).

[0149] [3] Thermoplastic resin The composition of the present invention preferably contains a thermoplastic resin because the effects of the present invention are more excellent. Examples of thermoplastic resins include natural resins such as terpene resins and rosin resins, and synthetic resins such as petroleum-based resins, coal-based resins, phenol-based resins, and xylene-based resins. Among these, terpene resins are preferred because they provide better 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 better effects of the present invention.

[0150] [Softening point] 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, because the effects of the present invention are more excellent. The upper limit of the softening point is preferably 170° C. or lower, more preferably 150° C. or lower, because the effects of the present invention are more excellent. The softening point here is a softening point measured in accordance with JIS K2207:1996.

[0151] [Content] 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, per 100 parts by mass of the above-mentioned rubber component, because this provides better effects of the present invention.

[0152] [4] Liquid diene rubber 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.

[0153] [Preferred embodiment] The liquid diene rubber preferably has a functional group derived from a silane compound represented by the following general formula (II) because this provides a better effect of the present invention.

[0154] [ka]

[0155] In 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, provided that R 2 , R 3 and R 4 At least one of the groups is a methoxy group, an ethoxy group, or a phenoxy group.

[0156] [Molecular weight] 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, because the effects of the present invention are more excellent.

[0157] [Content] In the composition of the present invention, the content of the liquid diene-based rubber is preferably 1.0 to 15.0 mass %, and more preferably 5.0 to 10.0 mass %, relative to the above-mentioned silica content (the total content of all silicas including the specific silica), because the effects of the present invention are more excellent.

[0158] [B] Tire The tire of the present invention is a tire manufactured using the above-mentioned composition of the present invention. The tire of the present invention is preferably a pneumatic tire, and can be filled with air, an inert gas such as nitrogen, and other gases. In particular, the tire is preferably a pneumatic tire using (disposing) the composition of the present invention in the tire tread (cap tread). FIG. 1 shows a partial cross-sectional schematic view of a tire representing one example of an embodiment of a tire of the present invention, but the tire of the present invention is not limited to the embodiment shown in FIG.

[0159] In FIG. 1, reference numeral 1 denotes a bead portion, reference numeral 2 denotes a sidewall portion, and reference numeral 3 denotes a tire tread portion. Between the pair of left and right bead portions 1, a carcass layer 4 having fiber cords embedded therein is installed, and the ends of this carcass layer 4 are folded back and wrapped around the bead cores 5 and bead fillers 6 from the inside to the outside of the tire. In the tire tread portion 3, a belt layer 7 is disposed on the outer side of the carcass layer 4 over one circumference of the tire. In addition, a rim cushion 8 is disposed in the bead portion 1 at a portion that comes into contact with the rim. The tire tread portion 3 is formed from the above-mentioned composition of the present invention.

[0160] The tire of the present invention can be manufactured, for example, according to a conventionally known method. The gas to be filled in the tire can be normal air or air with an adjusted oxygen partial pressure, or an inert gas such as nitrogen, argon, or helium. EXAMPLES

[0161] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0162] [Production of specific conjugated diene rubber 1] Specific conjugated diene rubber 1 was produced as follows.

[0163] [Process A] Into a nitrogen-purged 800-ml vessel, 140.89 cyclohexane and 3.0 mmol of tetramethylethylenediamine were added, and further 30.0 mmol of n-butyllithium was added. Next, 113.6 g of isoprene and 9.2 g of styrene were slowly added, and the mixture was reacted for 120 minutes in the vessel at 50° C. to obtain a polymer block (A) having an active terminal. 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 mass%, an isoprene monomer unit content of 92.5 mass%, and a vinyl bond content in the isoprene monomer unit of 7.0 mass%.

[0164] [Process B] In a nitrogen atmosphere, 6,400 g of cyclohexane, 2.95 mmol of tetramethylethylenediamine, 585 g of 1,3-butadiene, 615 g of styrene, and bis(diethylamino)methylvinylsilane (X in the above general formula (1)) were placed in an autoclave equipped with a stirrer. 1 = chemical single bond, X 2 and X 3 = diethylamino group, X 4 After charging 0.95 g of a compound (compound in which n is a methyl group), 7.01 mmol of n-butyllithium was added, and 0.51 mmol of the polymer block (A) having the active terminal was added in terms of lithium atom content, and polymerization was started at 40°C. 10 minutes after the start of polymerization, 300 g of 1,3-butadiene was continuously added over 60 minutes. After the continuous addition was completed, the polymerization reaction was continued for another 20 minutes, and it was confirmed that the polymerization conversion rate was in the range of 95% to 100%. In this way, a conjugated diene polymer chain having an active terminal and including polymer block (A) and polymer block (B) was obtained.

[0165] Bis(diethylamino)methylvinylsilane [ka]

[0166] [Process C] Next, polyorganosiloxane represented by the following formula (9) was added so that the content of -Si-O- repeating units was 7.15 mmol, and reacted for 30 minutes. Then, as a polymerization terminator, methanol was added in an amount equivalent to twice the moles of n-butyllithium used to obtain a solution containing a conjugated diene rubber. To this solution, 0.20 parts by mass of Irganox 1520L (manufactured by BASF) as an antiaging agent relative to 100 parts by mass of the conjugated diene rubber, and 15.0 parts by mass of extender oil (trade name "Aromax T-DAE", manufactured by JX Nippon Oil & Energy Corporation) relative to 100 parts by mass of the conjugated diene rubber were added, and the solvent was removed by steam stripping, and the mixture was vacuum dried at 60 ° C for 24 hours to obtain a solid conjugated diene rubber.

[0167] The weight average molecular weight (Mw) of the obtained conjugated diene rubber was 590,000, the styrene monomer unit content was 41% by weight, and the vinyl bond content was 25% by weight. The bis(diethylamino)methylvinylsilane monomer unit content in the obtained conjugated diene rubber was 0.06% by mass. The glass transition temperature of the obtained conjugated diene rubber was -26°C.

[0168] [ka]

[0169] The obtained conjugated diene rubber is a conjugated diene rubber having 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 having a modified structure with polyorganosiloxane (siloxane compound) represented by the above formula (9) at the end. The weight average molecular weight (Mw) of the polymer block (A) is in the range of 1,000 to 30,000, and the total weight average molecular weight (Mw) is in the range of 50,000 to 5,000,000. The total styrene monomer unit content (aromatic vinyl monomer unit content) is 30 to 45 mass%. Therefore, the obtained conjugated diene rubber corresponds to the above-mentioned specific conjugated diene rubber. The obtained conjugated diene rubber is also referred to as specific conjugated diene rubber 1.

[0170] [Comparative conjugated diene rubber] In step B, a conjugated diene rubber was produced according to the same procedure as in the production of specific conjugated diene rubber 1 described above, except that the amount of tetramethylethylenediamine was changed to 0.71 mmol, the amount of 1,3-butadiene was changed to 763 g, and the amount of styrene was changed to 28.7 g.

[0171] The weight average molecular weight (Mw) of the obtained conjugated diene rubber was 750,000, the styrene monomer unit content was 28 mass%, and the vinyl bond content was 59 mass%. The bis(diethylamino)methylvinylsilane monomer unit content in the obtained conjugated diene rubber was 0.15 mass%. The glass transition temperature of the obtained conjugated diene rubber was -21°C.

[0172] The obtained conjugated diene rubber is a conjugated diene rubber having 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 having a modified structure with polyorganosiloxane (siloxane compound) represented by the above formula (9) at the end. The weight average molecular weight (Mw) of the polymer block (A) is in the range of 1,000 to 30,000, and the total weight average molecular weight (Mw) is in the range of 50,000 to 5,000,000. On the other hand, the obtained conjugated diene rubber does not fall under the above-mentioned specific conjugated diene rubber because the total styrene monomer unit content (aromatic vinyl monomer unit content) is outside the range of 30 to 45 mass%. Moreover, the resulting conjugated diene rubber has a weight average molecular weight of less than 800,000, and therefore does not fall under the category of the above-mentioned specific copolymer rubber. The resulting conjugated diene rubber is also called comparative conjugated diene rubber.

[0173] [Preparation of rubber composition for tires] The components shown in Table 1 below were mixed in the ratios (parts by mass) shown in the same table. Specifically, the components shown in Table 1 below, excluding sulfur and a vulcanization accelerator, were first heated to about 140°C using a 1.7-liter internal Banbury mixer, mixed for 5 minutes, then discharged and cooled to room temperature to obtain a master batch. Furthermore, sulfur and a vulcanization accelerator were mixed into the obtained master batch using the Banbury mixer to obtain a rubber composition for tires. When the rubber component is an oil-extended product, the parts by mass indicate the net amount of rubber (amount excluding oil).

[0174] [evaluation] The obtained rubber compositions for tires were evaluated as follows.

[0175] [Shrink] The resulting rubber composition for tires was extrusion molded, and the shrinkage at that time was measured. The results are shown in Table 1. The smaller the index, the smaller the shrinkage and the more excellent the shrink resistance. A value of 95 or less is preferable.

[0176] [Heat resistance] A pneumatic tire was manufactured using the obtained rubber composition for tires. The obtained pneumatic tire was then mounted on a test vehicle, and a test driver performed a sensory evaluation (on a 5-point scale) on heat sagging resistance. The results are shown in Table 1. A higher value indicates better heat sagging resistance. A value of 4 or higher is preferable.

[0177] [Wear resistance] The obtained rubber composition for tires was press-vulcanized in a mold (15 cm×15 cm×0.2 cm) at 160° C. for 15 minutes to prepare a vulcanized rubber sheet. The amount of wear of the obtained vulcanized rubber sheet was measured at a temperature of 20° C. and a slip rate of 50% using a Lambourn abrasion tester (manufactured by Iwamoto Seisakusho) in accordance with JIS K6264-1, 2:2005. The abrasion resistance index was calculated from the following formula. The results are shown in Table 1. A larger index indicates a smaller amount of wear and better wear resistance. The wear resistance index is preferably 105 or more. Abrasion resistance index = (abrasion amount of Comparative Example 1 / abrasion amount of each vulcanized rubber sheet) x 100

[0178] [Table 1]

[0179] Details of each component in Table 1 above are as follows. Specific conjugated diene rubber 1: Specific conjugated diene rubber 1 produced as described above (as described above, specific conjugated diene rubber 1 corresponds to the specific conjugated diene rubber described above) Comparative conjugated diene rubber: Comparative conjugated diene rubber produced as described above (as described above, the comparative conjugated diene rubber does not fall under the above-mentioned specific conjugated diene rubber or the above-mentioned specific copolymer rubber) Rubber component 1: Solution-polymerized styrene butadiene rubber having polyorganosiloxane groups at the terminals and having isoprene blocks. (Oil-extended product (containing 25 parts by mass of oil-extended oil for 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) (Rubber component 1 does not contain units of a vinyl compound containing a functional group capable of interacting with silica, and therefore does not fall under the above-mentioned specific conjugated diene rubber. In addition, rubber component 1 has a weight-average molecular weight of less than 800,000, and therefore does not fall under the above-mentioned specific copolymer rubber.) E581: TUFDENE E581 manufactured by Asahi Kasei Corporation (terminal-modified solution-polymerized SBR having a hydroxyl group at the end, styrene monomer unit content: 36% by mass, vinyl bond content: 41% by mass, weight average molecular weight: 1,270,000, Tg: -30°C) (E581 is an SBR other than the specific conjugated diene rubber described above. E581 has a styrene monomer unit (aromatic vinyl monomer unit) content of 23 to 50% by mass and a weight average molecular weight of 800,000 or more. In addition, since the difference between the styrene monomer unit (aromatic vinyl monomer unit) content of the specific conjugated diene rubber 1 and the styrene monomer unit (aromatic vinyl monomer unit) content of E581 is 10% by mass or less, E581 corresponds to the specific copolymer rubber described above in relation to the specific conjugated diene rubber 1.) Rubber component 2: SBR produced as follows: In a nitrogen-purged 10L autoclave reactor, 4533g of cyclohexane, 338.9g (3.254mol) of styrene, 468.0g (8.652mol) of butadiene, 20.0g (0.294mol) of isoprene, and 0.189mL (1.271mmol) of N,N,N′,N′-tetramethylethylenediamine were charged and stirring was started. After the temperature of the contents in the reaction vessel was raised to 50°C, 5.061mL (7.945mmol) of n-butyllithium was added. After the polymerization conversion rate reached almost 100%, 12.0g of isoprene was added and reacted for 5 minutes, and then 0.281g (0.318mmol) of a 40wt% toluene solution of 1,6-bis(trichlorosilyl)hexane was added and reacted for 30 minutes. Further, the polyorganosiloxane represented by the above formula (9) was added in the form of a xylene solution with a concentration of 20% by mass so that the content of epoxy groups was 1.00 mmol (equivalent to 0.13 times the molar amount of n-butyl lithium used), and reacted for 30 minutes. 0.5 mL of methanol was added and stirred for 30 minutes to obtain a solution containing a conjugated diene rubber. A small amount of an anti-aging agent (Irganox 1520, manufactured by BASF) was added to the obtained solution, and 25 parts by mass of Fukkol Elamic 30 (manufactured by Nippon Oil Corporation) was added as an extender oil relative to 100 parts by mass of the conjugated diene rubber, and then a solid rubber was recovered by a steam stripping method. The obtained solid rubber was dehydrated by a roll and dried in a dryer to obtain a solid conjugated diene rubber (SBR). The rubber component 2 is an SBR other than the above-mentioned specific conjugated diene rubber. The rubber component 2 has a weight average molecular weight of less than 800,000, and therefore does not fall under the above-mentioned specific copolymer rubber. HP776: SBR (styrene monomer unit content: 32% by mass, vinyl bond content: 59% by mass, weight average molecular weight: 1,210,000, Tg: -24°C) (HP776 is an SBR other than the specific conjugated diene rubber described above. HP776 has a styrene monomer unit (aromatic vinyl monomer unit) content of 23 to 50% by mass and a weight average molecular weight of 800,000 or more. On the other hand, since the difference between the styrene monomer unit (aromatic vinyl monomer unit) content of specific conjugated diene rubber 1 and the styrene monomer unit (aromatic vinyl monomer unit) content of HP776 exceeds 10% by mass, HP776 does not fall under the specific copolymer rubber described above in relation to specific conjugated diene rubber 1.) NS612: NS612 manufactured by Zeon Corporation (solution polymerization SBR, styrene monomer unit content: 15% by mass, vinyl bond content: 31% by mass, weight average molecular weight: 440,000, Tg-61°C) (NS612 is an SBR other than the specific conjugated diene rubber mentioned above. Since NS612 has a weight average molecular weight of less than 800,000, it does not fall under the specific copolymer rubber mentioned above.) ·7000GR: ULTRASIL 7000GR (Silica, CTAB adsorption specific surface area: 160m 2 / g, manufactured by Evonik) ·9100GR: ULTRASIL 9100GR (Silica, CTAB adsorption specific surface area: 200m 2 / g, manufactured by Evonik) N339: Show Black N339 (carbon black, manufactured by Cabot Japan) NXT: A silane coupling agent represented by the above-mentioned general formula (S) (wherein, in the above-mentioned general formula (S), n=2, m=3, and k=7). Zinc oxide: Three types of zinc oxide (manufactured by Seido Chemical Industry Co., Ltd.) Stearic acid: Beads stearic acid (NOF Corporation) Anti-aging agent: Ozonone 6C (Seiko Chemical Co., Ltd.) Process oil: Extract No. 4S (Showa Shell Sekiyu) Alkylsilane: Octyltriethoxysilane (KBE-3083, Shin-Etsu Chemical Co., Ltd.) (Alkylsilane corresponds to the specific alkyltriethoxysilane mentioned above) Thermoplastic resin: Yasuhara Chemical's YS Resin TO125 (aromatic modified terpene resin, softening point: 125°C) Modified LBR: Modified liquid diene rubber produced as follows: A 5L autoclave that was thoroughly dried was purged with nitrogen, and 1200g of hexane and 22g of n-butyllithium (17% by mass hexane solution) were charged. The temperature was raised to 50°C, and then 1460g of butadiene was added successively while controlling the polymerization temperature to 50°C under stirring conditions, and polymerization was carried out for 1 hour. Methanol was then added to terminate the polymerization reaction, and a polymer solution was obtained. Water was added to the obtained polymer solution, and the mixture was stirred, and the polymer solution was washed with water. After stopping the stirring, it was confirmed that the polymer solution phase and the water phase were separated, and then 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. Next, 700 g of the unmodified liquid diene rubber obtained was charged into a 1 L autoclave and degassed with nitrogen while stirring at 60°C for 3 hours. 1.0 g of 1,1-bis(t-hexylperoxy)cyclohexane and 25 g of (3-mercaptopropyl)trimethoxysilane were added and reacted at 105°C for 8 hours to obtain a modified liquid diene rubber. The weight average molecular weight of the modified liquid diene rubber obtained was 55,000. The modified liquid diene rubber obtained is a liquid BR having a functional group derived from the silane compound represented by the above-mentioned general formula (II). Sulfur: Kinkaji oil-filled fine sulfur (sulfur content 95.24% by mass, manufactured by Tsurumi Chemical Industry Co., Ltd.) Vulcanization accelerator (CZ): Noccela CZ-G manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Vulcanization accelerator (DPG): 1,3-diphenylguanidine (Soxinol DG, manufactured by Sumitomo Chemical Co., Ltd.)

[0180] In Table 1, St represents the styrene monomer unit content (% by mass), Vn represents the vinyl bond content (% by mass), and Mw represents the weight average molecular weight (×10 4) and Tg represents the glass transition temperature (°C).

[0181] As can be seen from Table 1, Examples 1 to 6, in which a specific conjugated diene rubber and a specific copolymer rubber were used in combination in a specified amount and the aromatic monomer units of the two were in a specified relationship, showed excellent shrink resistance, heat sagging resistance, and abrasion resistance. Comparing Example 1 and Example 2 (comparison between the embodiments in which 7000GR was used as silica), Example 2, in which the content of the specific conjugated diene rubber in the rubber component was 60 mass% or more, showed superior shrink resistance and heat sagging resistance. In addition, comparing Example 1 and Example 2 (comparison between the embodiments in which 7000GR was used as silica), Example 1, in which the content of the specific conjugated diene rubber in the rubber component was 60 mass% or less, exhibited superior abrasion resistance. In addition, comparing Example 1 and Example 3 (comparison between embodiments differing only in the type of silica), Example 3, in which the silica contains 20 parts by mass or more of the above-mentioned specific silica, exhibited superior heat sagging resistance and abrasion resistance. Furthermore, a comparison between Example 3 and Example 4 (a comparison between the two embodiments that differ only in the presence or absence of alkylsilane) revealed that Example 4, which contained the specific alkyltriethoxysilane, exhibited superior abrasion resistance. Moreover, a comparison between Example 3 and Example 5 (a comparison between the two embodiments that differ only in the presence or absence of modified LBR) revealed that Example 5, which contained the liquid diene rubber, exhibited superior abrasion resistance. Furthermore, a comparison between Example 3 and Example 6 (a comparison between the two embodiments that differ only in the presence or absence of a thermoplastic resin) showed that Example 6, which contains a thermoplastic resin, exhibited superior shrink resistance and abrasion resistance.

[0182] On the other hand, Comparative Example 1, Comparative Example 4, and Comparative Example 7 do not contain the specific conjugated diene rubber, Comparative Example 2 contains the specific conjugated diene rubber but the content of the specific copolymer rubber in the rubber component is less than 35% by mass, and Comparative Example 3 uses the specific conjugated diene rubber and the specific copolymer rubber in combination but the content of the specific copolymer rubber in the rubber component is less than 25% by mass. , averageIn addition, Comparative Example 6, which contained the specific conjugated diene rubber but did not contain the specific copolymer rubber, was insufficient in at least one of shrink resistance, heat sagging resistance, and abrasion resistance. [Explanation of symbols]

[0183] 1 Bead section 2 Sidewall 3 Tire tread 4 Carcass layer 5 Bead Core 6 Bead Filler 7 Belt layer 8 Rim cushion

Claims

1. The rubber composition contains a rubber component, silica, and a silane coupling agent, The rubber component contains a specific conjugated diene rubber and a specific copolymer 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 copolymer rubber is 25% by mass or more, The specific conjugated diene rubber is 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 siloxane compound-modified structure at at least one end, 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, and the unit of the vinyl compound containing a functional group capable of interacting with silica is a unit represented by the following general formula (3): The weight average molecular weight (Mw) of the polymer block (A) is in the range of 1,000 to 30,000, and the total weight average molecular weight (Mw) is in the range of 50,000 to 5,000,000, a conjugated diene rubber having a total aromatic vinyl monomer unit content of 30 to 45 mass% (excluding conjugated diene rubbers further having a modified structure with a compound represented by the following general formula (X) via a structure derived from the siloxane compound); The specific copolymer rubber is an aromatic vinyl-conjugated diene copolymer rubber other than the specific conjugated diene rubber, an aromatic vinyl monomer unit content of 35 to 50 mass%, and a difference from the aromatic vinyl monomer unit content of the entire specific conjugated diene rubber is 10 mass% or less; An aromatic vinyl-conjugated diene copolymer rubber having a weight average molecular weight (Mw) of 800,000 or more, The content of the silica is 50 to 150 parts by mass based on 100 parts by mass of the rubber component, The rubber composition for tires, wherein the content of the silane coupling agent is 3 to 30 mass % based on the content of the silica. [Formula 1] In general formula (3), X ５ represents a chemical single bond or a hydrocarbylene 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. [chemical 2] In general formula (X), R ９ is a hydrocarbyl group. In general formula (X), A １ is a group capable of reacting with a reaction residue formed by the reaction of a conjugated diene polymer chain having an active terminal with a polyorganosiloxane. In general formula (X), A ２ is a group containing a nitrogen atom. In formula (X), p is an integer of 0 to 2, q is an integer of 1 to 3, r is an integer of 1 to 3, and p+q+r=4.

2. The rubber composition contains a rubber component, silica, and a silane coupling agent, The rubber component contains a specific conjugated diene rubber and a specific copolymer 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 copolymer rubber is 25% by mass or more, The specific conjugated diene rubber is 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 siloxane compound-modified structure at at least one end, 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, and the unit of the vinyl compound containing a functional group capable of interacting with silica is a unit represented by the following general formula (3): The weight average molecular weight (Mw) of the polymer block (A) is in the range of 1,000 to 30,000, and the total weight average molecular weight (Mw) is in the range of 50,000 to 5,000,000, A conjugated diene rubber having a total aromatic vinyl monomer unit content of 35 to 45 mass% (excluding conjugated diene rubbers further having a modified structure with a compound represented by the following general formula (X) via a structure derived from the siloxane compound), The specific copolymer rubber is an aromatic vinyl-conjugated diene copolymer rubber other than the specific conjugated diene rubber, an aromatic vinyl monomer unit content of 30 to 50 mass%, and a difference between the aromatic vinyl monomer unit content of the specific conjugated diene rubber and the aromatic vinyl monomer unit content of the entire specific conjugated diene rubber is 10 mass% or less; The vinyl bond content in the conjugated diene monomer unit is 50 mass% or less, An aromatic vinyl-conjugated diene copolymer rubber having a weight average molecular weight (Mw) of 800,000 or more, The content of the silica is 50 to 150 parts by mass based on 100 parts by mass of the rubber component, The rubber composition for tires, wherein the content of the silane coupling agent is 3 to 30 mass % based on the content of the silica. [C3] In general formula (3), X ５ represents a chemical single bond or a hydrocarbylene 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. [C4] In general formula (X), R ９is a hydrocarbyl group. In general formula (X), A １ is a group capable of reacting with a reaction residue formed by the reaction of a conjugated diene polymer chain having an active terminal with a polyorganosiloxane. In general formula (X), A ２ is a group containing a nitrogen atom. In formula (X), p is an integer of 0 to 2, q is an integer of 1 to 3, r is an integer of 1 to 3, and p+q+r=4.

3. Further, the thermoplastic resin has a softening point of 50° C. or higher.

3. The rubber composition for tires according to claim 1, wherein the content of the thermoplastic resin is 1 to 20 parts by mass based on 100 parts by mass of the rubber component.

4. The silica has a CTAB adsorption specific surface area of ​​190 m ２ The rubber composition for tires according to any one of claims 1 to 3, comprising 20 parts by mass or more of specific silica, which is silica having a molecular weight of 1 / g or more.

5. Furthermore, it contains an alkyltriethoxysilane represented by the following general formula (I): The rubber composition for tires according to any one of claims 1 to 4, wherein the content of the alkyltriethoxysilane is 2.0 to 15.0 mass % based on the content of the silica. [C5] In general formula (I), R １ represents an alkyl group having 7 to 20 carbon atoms, and Et represents an ethyl group.

6. Further, the liquid diene rubber has a weight average molecular weight of 3,000 or more. The rubber composition for tires according to any one of claims 1 to 5, wherein the content of the liquid diene rubber is 1.0 to 15.0 mass % based on the content of the silica.

7. The rubber composition for tires 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): [C6] In 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 the groups is a methoxy group, an ethoxy group, or a phenoxy group.

8. A tire produced using the rubber composition for tires according to any one of claims 1 to 7.

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