# US 9,006,326 B2 · Rubber composition and pneumatic tire > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,006,326 B2 - Document ID: US9006326B2 - Status: Granted - Kind: B2 - Application number: 14/347,290 - Filed: 2012-06-26 - Published: 2014-08-14 - Granted: 2015-04-14 - Earliest claimed: 2011-11-24 - Assignees: Sumitomo Rubber Industries, Ltd. - Applicants: Shuichiro Ono; Ryuichi Tokimune - Inventors: Shuichiro Ono; Ryuichi Tokimune - Web page: https://patentgrep.com/patent/US9006326B2 ## CPC - C08K 3/36: Silica - B60C 1/0016: {Compositions of the tread} - C08C 19/44: of polymers containing metal atoms exclusively at one or both ends of the skeleton - C08K 5/548: containing sulfur {(C08K5/5477 takes precedence)} - C08F 230/085: {the monomer being a polymerisable silane, e.g. (meth)acryloyloxy trialkoxy silanes or vinyl trialkoxysilanes} - C08K: Use of inorganic or non-macromolecular organic substances as compounding ingredients (paints, inks, varnishes, dyes, polishes, adhesives C09) - B60C: VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES - C08C: TREATMENT OR CHEMICAL MODIFICATION OF RUBBERS - C08F: MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS ## Abstract Provided are a rubber composition capable of achieving a balanced improvement in fuel economy, tensile strength at break, and processability, and a pneumatic tire including the rubber composition. The invention relates to a rubber composition including a conjugated diene polymer and silica, the conjugated diene polymer being obtained by polymerizing a monomer component including a conjugated diene compound and a silicon-containing vinyl compound in the presence of a polymerization initiator represented by the following formula (I): to produce a copolymer, and reacting a compound containing a nitrogen atom and/or a silicon atom with an active terminal of the copolymer, wherein the rubber composition includes the conjugated diene polymer in an amount of not less than 10% by mass per 100% by mass of a rubber component of the rubber composition, and the silica in an amount of 10-70 parts by mass per 100 parts by mass of the rubber component. ## Claims ### Claim 1 A rubber composition, comprising a conjugated diene polymer and silica, the conjugated diene polymer being obtained by polymerizing a monomer component including a conjugated diene compound and a silicon-containing vinyl compound in the presence of a polymerization initiator represented by the following formula (I): wherein i represents 0 or 1; R11 represents a C1-100 hydrocarbylene group; R12 and R13 each represent an optionally substituted hydrocarbyl group or a trihydrocarbylsilyl group, or R12 and R13 are bonded to each other to form a hydrocarbylene group optionally containing at least one, as a hetero atom, selected from the group consisting of a silicon atom, a nitrogen atom, and an oxygen atom; and M represents an alkali metal atom, to produce a copolymer, and then reacting a compound containing at least one of a nitrogen atom and a silicon atom with an active terminal of the copolymer, wherein the rubber composition comprises the conjugated diene polymer in an amount of not less than 10% by mass based on 100% by mass of a rubber component of the rubber composition, and the silica in an amount of 10 to 70 parts by mass for each 100 parts by mass of the rubber component. ### Claim 2 (depends on 1) The rubber composition according to claim 1, wherein R11 in the formula (I) is a group represented by the following formula (Ia): CH2n—R14— (Ia) wherein R14 represents a hydrocarbylene group comprising at least one of a structural unit derived from a conjugated diene compound and a structural unit derived from an aromatic vinyl compound; and n represents an integer of 1 to 10. ### Claim 3 (depends on 2) The rubber composition according to claim 2, wherein R14 in the formula (Ia) is a hydrocarbylene group comprising from one to ten isoprene-derived structural unit(s). ### Claim 4 (depends on 1) The rubber composition according to claim 1, wherein the silicon-containing vinyl compound is a compound represented by the following formula (II): wherein m represents 0 or 1; R21 represents a hydrocarbylene group; and X1, X2, and X3 each represent a substituted amino group, a hydrocarbyloxy group, or an optionally substituted hydrocarbyl group. ### Claim 5 (depends on 1) The rubber composition according to claim 1, wherein the conjugated diene polymer contains a structural unit derived from an aromatic vinyl compound. ### Claim 6 (depends on 1) The rubber composition according to claim 1, wherein the silica has a nitrogen adsorption specific surface area of 40 to 400 m2/g. ### Claim 7 (depends on 1) The rubber composition according to claim 1, wherein the silica includes silica (1) having a nitrogen adsorption specific surface area of at least 40 m2/g but less than 120 m2/g, and silica (2) having a nitrogen adsorption specific surface area of not less than 120 m2/g. ### Claim 8 (depends on 1) The rubber composition according to claim 1, comprising a liquid resin having a softening point of −20 to 20° C. in an amount of 1 to 10 parts by mass for each 100 parts by mass of the rubber component. ### Claim 9 (depends on 1) The rubber composition according to claim 1, wherein the silica includes silica (1) having a nitrogen adsorption specific surface area of at least 40 m2/g but less than 120 m2/g, and silica (2) having a nitrogen adsorption specific surface area of not less than 120 m2/g, and the rubber composition comprises a liquid resin having a softening point of −20 to 20° C. in an amount of 1 to 10 parts by mass for each 100 parts by mass of the rubber component. ### Claim 10 (depends on 1) The rubber composition according to claim 1, comprising a mercapto group-containing silane coupling agent in an amount of 1 to 20 parts by mass for each 100 parts by mass of the silica. ### Claim 11 (depends on 1) The rubber composition according to claim 1, wherein the rubber composition comprises a mercapto group-containing silane coupling agent in an amount of 1 to 20 parts by mass for each 100 parts by mass of the silica, and the silica includes silica (1) having a nitrogen adsorption specific surface area of at least 40 m2/g but less than 120 m2/g, and silica (2) having a nitrogen adsorption specific surface area of not less than 120 m2/g. ### Claim 12 (depends on 11) The rubber composition according to claim 11, comprising a mercapto group-containing silane coupling agent in an amount of 1 to 20 parts by mass for each 100 parts by mass of the silica, and a liquid resin having a softening point of −20 to 20° C. in an amount of 1 to 10 parts by mass for each 100 parts by mass of the rubber component. ### Claim 13 (depends on 1) The rubber composition according to claim 1, wherein the rubber composition comprises a mercapto group-containing silane coupling agent in an amount of 1 to 20 parts by mass for each 100 parts by mass of the silica, the silica includes silica (1) having a nitrogen adsorption specific surface area of at least 40 m2/g but less than 120 m2/g, and silica (2) having a nitrogen adsorption specific surface area of not less than 120 m2/g, and the rubber composition comprises a liquid resin having a softening point of −20 to 20° C. in an amount of 1 to 10 parts by mass for each 100 parts by mass of the rubber component. ### Claim 14 (depends on 1) The rubber composition according to claim 1, wherein the rubber composition comprises a mercapto group-containing silane coupling agent in an amount of 1 to 20 parts by mass for each 100 parts by mass of the silica, and the silane coupling agent is at least one of a compound represented by the formula (1) below, and a compound containing a linking unit A represented by the formula (2) below and a linking unit B represented by the formula (3) below, wherein R101 to R103 each represent a branched or unbranched C1-12 alkyl group, a branched or unbranched C1-12 alkoxy group, or a group represented by —O—(R111—O)z—R112 where z R111 s each represent a branched or unbranched C1-30 divalent hydrocarbon group, and z R111 s may be the same as or different from one another; R112 represents a branched or unbranched C1-30 alkyl group, a branched or unbranched C2-30 alkenyl group, a C6-30 aryl group, or a C7-30 aralkyl group; and z represents an integer of 1 to 30, and be to R101 to R103 may be the same as or different from one another; and R104 represents a branched or unbranched C1-6 alkylene group; wherein R201 represents a hydrogen atom, a halogen atom, a branched or unbranched C1-30 alkyl group, a branched or unbranched C2-30 alkenyl group, a branched or unbranched C2-30 alkynyl group, or the alkyl group in which a terminal hydrogen atom is replaced with a hydroxy group or a carboxyl group; R202 represents a branched or unbranched C1-30 alkylene group, a branched or unbranched C2-30 alkenylene group, or a branched or unbranched C2-30 alkynylene group; and R201 and R202 may be joined together to form a cyclic structure. ### Claim 15 (depends on 1) The rubber composition according to claim 1, wherein the silica includes silica (1) having a nitrogen adsorption specific surface area of at least 40 m2/g but less than 120 m2/g, and silica (2) having a nitrogen adsorption specific surface area of not less than 120 m2/g, and the nitrogen adsorption specific surface areas and amounts of the silica (1) and the silica (2) satisfy the following inequalities: (Nitrogen adsorption specific surface area of silica (2))/(Nitrogen adsorption specific surface area of silica (1))≧1.4, and (Amount of silica (1))×0.06≦(Amount of silica (2))≦(Amount of silica (1))×15. ### Claim 16 (depends on 1) A pneumatic tire, formed from the rubber composition according to claim 1. ### Claim 17 (depends on 2) The rubber composition according to claim 2, wherein the silicon-containing vinyl compound is a compound represented by the following formula (II): wherein m represents 0 or 1; R21 represents a hydrocarbylene group; and X1, X2, and X3 each represent a substituted amino group, a hydrocarbyloxy group, or an optionally substituted hydrocarbyl group. ### Claim 18 (depends on 3) The rubber composition according to claim 3, wherein the silicon-containing vinyl compound is a compound represented by the following formula (II): wherein m represents 0 or 1; R21 represents a hydrocarbylene group; and X1, X2, and X3 each represent a substituted amino group, a hydrocarbyloxy group, or an optionally substituted hydrocarbyl group. ### Claim 19 (depends on 2) The rubber composition according to claim 2, wherein the conjugated diene polymer contains a structural unit derived from an aromatic vinyl compound. ### Claim 20 (depends on 3) The rubber composition according to claim 3, wherein the conjugated diene polymer contains a structural unit derived from an aromatic vinyl compound.