# US 2017/0283518 A1 · Rubber Composition for Tires and Pneumatic Tire

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- Number: US 2017/0283518 A1
- Document ID: US20170283518A1
- Status: Published application
- Kind: A1
- Application number: 15/507,212
- Filed: 2015-08-24
- Published: 2017-10-05
- Earliest claimed: 2014-08-27
- Assignees: The Yokohama Rubber Co., Ltd.
- Applicants: The Yokohama Rubber Co., LTD.
- Inventors: Keisuke Maejima; Masaki Sato; Makoto Ashiura
- Web page: https://patentgrep.com/patent/US20170283518A1

## CPC

- C08C 19/30: Addition of a reagent which reacts with a hetero atom or a group containing hetero atoms of the macromolecule
- B60C 1/00: Tyres characterised by the chemical composition or the physical arrangement or mixture of the composition
- C08C 19/36: with carboxy radicals
- C08C 19/38: with hydroxy radicals
- C08F 8/42: Introducing metal atoms or metal-containing groups
- C08F 297/044: {using a coupling agent}
- C08F 297/046: {polymerising vinyl aromatic monomers and isoprene, optionally with other conjugated dienes}
- C08K 3/36: Silica
- C08K 5/5419: containing at least one Si—C bond
- C08L 9/00: Compositions of homopolymers or copolymers of conjugated diene hydrocarbons
- C08L 15/00: Compositions of rubber derivatives (C08L11/00, C08L13/00 take precedence)
- C08L 53/025: {modified}
- B60C 1/0016: {Compositions of the tread}
- C08C: TREATMENT OR CHEMICAL MODIFICATION OF RUBBERS
- B60C: VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- C08F: MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08K: Use of inorganic or non-macromolecular organic substances as compounding ingredients (paints, inks, varnishes, dyes, polishes, adhesives C09)
- C08L: COMPOSITIONS OF MACROMOLECULAR COMPOUNDS (compositions based on polymerisable monomers C08F, C08G; artificial filaments or fibres D01F; textile treating compositions D06)

## Abstract

A rubber composition for tires of the present technology contains a diene rubber, silica, and a predetermined alkyltrialkoxysilane; the diene rubber containing a butadiene rubber and a particular conjugated diene rubber, a content of the butadiene rubber in the diene rubber being 20 mass % or greater and a content of the particular conjugated diene rubber in the diene rubber being from 30 to 80 mass %; an average glass transition temperature of the diene rubber being from −65 to −45° C.; the particular conjugated diene rubber being a conjugated diene rubber produced by a particular production method and having predetermined ranges of aromatic vinyl unit content, vinyl bond content, and weight average molecular weight.

## Claims

### Claim 1

A rubber composition for tires comprising a diene rubber, silica, and an alkyltrialkoxysilane represented by Formula (I);
the diene rubber containing a butadiene rubber and a particular conjugated diene rubber, a content of the butadiene rubber in the diene rubber being 20 mass % or greater and a content of the particular conjugated diene rubber in the diene rubber being from 30 to 80 mass %;
an average glass transition temperature of the diene rubber being from −65 to −45° C.;
a content of the silica being from 90 to 150 parts by mass per 100 parts by mass of the diene rubber;
a content of the alkyltrialkoxysilane being from 0.1 to 8 mass % relative to the content of the silica;
wherein, R11 represents an alkyl group having from 1 to 20 carbons, and R12 each independently represents a methyl group or an ethyl group;
the particular conjugated diene rubber being a conjugated diene rubber produced by a method of producing a conjugated diene rubber, the method comprising steps A, B, and C below in this order;
the particular conjugated diene rubber having an aromatic vinyl unit content of 38 to 48 mass %, a vinyl bond content of 20 to 35 mass %, and a weight average molecular weight of 500000 to 800000;
Step A: a step of forming a polymer block A having an active terminal, the polymer block A having an isoprene unit content of 80 to 95 mass %, an aromatic vinyl unit content of 5 to 20 mass %, and a weight average molecular weight of 500 to 15000, by polymerizing a monomer mixture containing isoprene and an aromatic vinyl;
Step B: a step of obtaining a conjugated diene-based polymer chain having an active terminal, the conjugated diene-based polymer chain having the polymer block A and a polymer block B, by forming the polymer block B having an active terminal by mixing the polymer block A with a monomer mixture containing 1,3-butadiene and an aromatic vinyl to continue polymerization reaction to form the polymer block B in series with the polymer block A; and
Step C: a step of reacting a polyorganosiloxane represented by Formula (1) with the active terminal of the conjugated diene-based polymer chain;
wherein, R1 to R8 are the same or different and are each an alkyl group having from 1 to 6 carbons or an aryl group having from 6 to 12 carbons; X1 and X4 are the same or different and are groups selected from the group consisting of alkyl groups having from 1 to 6 carbons, aryl groups having from 6 to 12 carbons, alkoxy groups having from 1 to 5 carbons, and groups having an epoxy group and from 4 to 12 carbons; X2 is an alkoxy group having from 1 to 5 carbons or a group having an epoxy group and from 4 to 12 carbons, and a plurality of the X2 moieties are the same or different; X3 is a group having from 2 to 20 alkylene glycol repeating units, and when a plurality of the X3 moieties exists, the X3 moieties are the same or different; and m is an integer from 3 to 200, n is an integer from 0 to 200, and k is an integer from 0 to 200.

### Claim 2 (depends on 1)

The rubber composition for tires according to claim 1, further comprising a silane coupling agent, the silane coupling agent and the silica satisfying Equation (A);
[content of silane coupling agent(g)×100/{content of silica(g)×CTAB adsorption specific surface area(m2/g)}]×100=3.5 to 7.5. Equation (A):

### Claim 3 (depends on 1)

The rubber composition for tires according to claim 1, wherein the silica contains 50 mass % or greater of silica (X) having a CTAB adsorption specific surface area of 80 to 130 m2/g.

### Claim 4 (depends on 1)

The rubber composition for tires according to claim 1, further comprising an aromatic modified terpene resin having a softening point of 100 to 150° C.,
a content of the aromatic modified terpene resin being from 3 to 20 parts by mass per 100 parts by mass of the diene rubber.

### Claim 5 (depends on 1)

A pneumatic tire having the rubber composition for tires described in claim 1 in a cap tread.

### Claim 6 (depends on 5)

The pneumatic tire according to claim 5, the pneumatic tire being used for a winter tire.

### Claim 7 (depends on 2)

The rubber composition for tires according to claim 2, wherein the silica contains 50 mass % or greater of silica (X) having a CTAB adsorption specific surface area of 80 to 130 m2/g.

### Claim 8 (depends on 2)

The rubber composition for tires according to claim 2, further comprising an aromatic modified terpene resin having a softening point of 100 to 150° C.,
a content of the aromatic modified terpene resin being from 3 to 20 parts by mass per 100 parts by mass of the diene rubber.

### Claim 9 (depends on 3)

The rubber composition for tires according to claim 3, further comprising an aromatic modified terpene resin having a softening point of 100 to 150° C.,
a content of the aromatic modified terpene resin being from 3 to 20 parts by mass per 100 parts by mass of the diene rubber.

### Claim 10 (depends on 7)

The rubber composition for tires according to claim 7, further comprising an aromatic modified terpene resin having a softening point of 100 to 150° C.,
a content of the aromatic modified terpene resin being from 3 to 20 parts by mass per 100 parts by mass of the diene rubber.

### Claim 11 (depends on 2)

A pneumatic tire having the rubber composition for tires described in claim 2 in a cap tread.

### Claim 12 (depends on 3)

A pneumatic tire having the rubber composition for tires described in claim 3 in a cap tread.

### Claim 13 (depends on 4)

A pneumatic tire having the rubber composition for tires described in claim 4 in a cap tread.

### Claim 14 (depends on 7)

A pneumatic tire having the rubber composition for tires described in claim 7 in a cap tread.

### Claim 15 (depends on 8)

A pneumatic tire having the rubber composition for tires described in claim 8 in a cap tread.

### Claim 16 (depends on 9)

A pneumatic tire having the rubber composition for tires described in claim 9 in a cap tread.

### Claim 17 (depends on 10)

A pneumatic tire having the rubber composition for tires described in claim 10 in a cap tread.