Rubber composition and pneumatic tire

Patent metadata

Field	Value
Publication number	US-9845385-B2
Application number	US-201214007575-A
Country	US
Kind code	B2
Filing date	Apr 27, 2012
Priority date	Apr 28, 2011
Publication date	Dec 19, 2017
Grant date	Dec 19, 2017

Abstract

The present invention provides a rubber composition that can enhance the fuel economy, wet-grip performance, abrasion resistance, and kneading processability in a balanced manner, and a pneumatic tire using this rubber composition. The present invention relates to a rubber composition that contains a rubber component and silica, wherein the rubber component contains, based on 100% by mass of the rubber component, 10 to 70% by mass of a high-cis polybutadiene having a cis content of 95% by mass or more and satisfying the following requirements (A) to (C): (A) a Mooney viscosity (ML) of 40 to 49; (B) a molecular weight distribution (weight-average molecular weight (Mw)/number-average molecular weight (Mn)) of 3.0 to 3.9; and (C) an index (n-value in Expression (1) below) of velocity dependence of Mooney viscosity of 2.3 to 3.0, and 30 to 90% by mass of a conjugated diene polymer containing a constituent unit based on a conjugated diene and a constituent unit represented by formula (I) below, and an amount of the silica is 5 to 150 parts by mass per 100 parts by mass of the rubber component,

log( ML )=log( K )+ n −1 ×log( RS )  (Expression 1)

wherein RS indicates the number of revolutions per minute of a rotor, K indicates an arbitrary number, and ML indicates a Mooney viscosity,

First claim

The invention claimed is:

1. A rubber composition, comprising a rubber component and silica,
wherein the rubber component contains, based on 100% by mass of the rubber component,
10 to 70% by mass of a high-cis polybutadiene having a cis content of 95% by mass or more and satisfying the following requirements (A) to (C): (A) a Mooney viscosity (ML) of 40 to 49; (B) a molecular weight distribution (weight-average molecular weight (Mw)/number-average molecular weight (Mn)) of 3.0 to 3.9; and (C) an index (n-value in Expression (1) below) of velocity dependence of Mooney viscosity of 2.3 to 3.0, and
30 to 90% by mass of a conjugated diene polymer containing a constituent unit based on a conjugated diene and a constituent unit represented by formula (I) below, at least one terminal of the polymer being modified with at least one compound selected from the group consisting of a compound represented by formula (II) below, a compound represented by formula (III) below, and a compound represented by formula (IVa) below, and
an amount of the silica is 5 to 150 parts by mass per 100 parts by mass of the rubber component,
log( ML )=log( K )+ n −1 ×log( RS )  (Expression 1)

wherein RS indicates the number of revolutions per minute of a rotor, K indicates an arbitrary number, and ML indicates a Mooney viscosity,

wherein X 1 , X 2 , and X 3 each independently represent a hydroxyl group or a C 1-4 alkyl group, and two of X 1 , X 2 , and X 3 are hydroxyl groups;

wherein n represents an integer of 1 to 10; R 11 , R 12 , and R 13 each independently represent a C 1-4 alkyl group or a C 1-4 alkoxy group, and at least one of R 11 , R 12 , and R 13 is an alkoxy group; and A 1 is a group represented by the formula (IIa):

wherein R 14 and R 15 each independently represent a C 1-6 alkyl group, a C 1-6 alkylene oxide group, a C 1-6 alkylene oxide alkyl group, or a C 1-6 trialkylsilyl group;

wherein m represents an integer of 1 to 10; R 21 represents a hydrogen atom, a C 1-6 alkyl group, or a C 1-6 alkoxyalkyl group; A 2 represents the following group: —NR 22 — where R 22 represents a hydrogen atom or a C 1-4 alkyl group; and A 3 is a group represented by the formula (IIIa):

wherein R 23 and R 24 each independently represent a C 1-6 alkyl group, a C 1-6 alkylene oxide group, a C 1-6 alkylene oxide alkyl group, or a C 1-6 trialkylsilyl group;

wherein q represents an integer of 0 to 10; R 31 represents a C 1-5 alkyl group; R 32 , R 33 , R 34 and R 35 each independently represent a hydrogen atom, a C 1-5 alkyl group, a C 1-5 alkoxyalkyl group, or a C 1-5 alkoxy group, and when a plurality of R 32 's and a plurality of R 33 's are present, the plurality of R 32 's and the plurality of R 33 's may be the same as or different from one another; and R 36 and R 37 each independently represent a C 1-6 alkyl group.

2. The rubber composition according to claim 1 ,
wherein one of R 34 and R 35 in formula (IVa) is a hydrogen atom.

3. The rubber composition according to claim 1 ,
wherein the conjugated diene polymer has a vinyl bond content of at least 10 mol % but not more than 80 mol % per 100 mol % of the constituent unit based on a conjugated diene.

4. The rubber composition according to claim 1 ,
wherein the high-cis polybutadiene has a ratio (Tcp/ML) of a 5% by mass toluene solution viscosity (Tcp) to the Mooney viscosity (ML) of 2.5 to 3.5.

5. The rubber composition according to claim 1 ,
wherein the high-cis polybutadiene has a Mw of 500,000 to 700,000 and a Mn of 120,000 to 250,000.

6. The rubber composition according to claim 1 ,
wherein the silica has a nitrogen adsorption specific surface area of 40 to 400 m 2 /g.

7. The rubber composition according to claim 1 , which is for use as a rubber composition for a tread.

8. A pneumatic tire, produced using the rubber composition according to claim 1 .

Assignees

• Mabuchi Takahiro
• Tanaka Tatsuhiro
• Nishioka Kazuyuki
• Uesaka Kenichi
• Sumitomo Rubber Ind

Inventors

• Mabuchi Takahiro
• Tanaka Tatsuhiro
• Nishioka Kazuyuki
• Uesaka Kenichi

Classifications

• C08L15/00

  Compositions of rubber derivatives (C08L11/00, C08L13/00 take precedence) · CPC title

• C08F230/08

  containing silicon · CPC title

• C08K3/36

  Silica · CPC title

• C08L9/00

  Compositions of homopolymers or copolymers of conjugated diene hydrocarbons · CPC title

• Y02T10/862

  Cross-Sectional Technologies · mapped topic