Rubber composition for tires and pneumatic tire

Patent metadata

Field	Value
Publication number	US-9856362-B2
Application number	US-201415100553-A
Country	US
Kind code	B2
Filing date	Nov 27, 2014
Priority date	Dec 27, 2013
Publication date	Jan 2, 2018
Grant date	Jan 2, 2018

Abstract

Provided are a rubber composition for tires that shows a balanced improvement in properties such as fuel economy, processability, heat aging resistance, abrasion resistance, wet-grip performance, performance on snow and ice, and handling stability, and a pneumatic tire formed from the rubber composition. The present invention relates to a rubber composition for tires, containing: a highly purified, modified natural rubber having a pH adjusted to 2 to 7, and a silica having a CTAB specific surface area of 180 m 2 /g or more and a BET specific surface area of 185 m 2 /g or more, and also relates to a pneumatic tire formed from the rubber composition.

First claim

The invention claimed is:

1. A rubber composition for tires, comprising:
a modified natural rubber having a phosphorus content of 200 ppm or less and further having a pH adjusted to 2 to 7, and
a silica having a CTAB specific surface area of 180 m 2 /g or more and a BET specific surface area of 185 m 2 /g or more.

2. The rubber composition for tires according to claim 1 , wherein the modified natural rubber is obtained by removing non-rubber components in natural rubber, followed by treatment with an acidic compound, and the modified natural rubber has a pH of 2 to 7.

3. The rubber composition for tires according to claim 1 , wherein the modified natural rubber is obtained by washing a saponified natural rubber latex and treating the washed saponified natural rubber latex with an acidic compound, and the modified natural rubber has a pH of 2 to 7.

4. The rubber composition for tires according to claim 1 , wherein the modified natural rubber is obtained by washing a deproteinized natural rubber latex and treating the washed deproteinized natural rubber latex with an acidic compound, and the modified natural rubber has a pH of 2 to 7.

5. The rubber composition for tires according to claim 1 , wherein the modified natural rubber has a nitrogen content of 0.15% by mass or less.

6. The rubber composition for tires according to claim 1 , wherein the pH is determined by cutting the modified natural rubber into pieces at most 2 mm square on each side, immersing the pieces in distilled water, irradiating the immersed pieces with microwaves for extraction at 90° C. for 15 minutes, and measuring the resulting immersion water with a pH meter.

7. The rubber composition for tires according to claim 1 , wherein the modified natural rubber has a heat aging resistance index of 75 to 120%, the heat aging resistance index being defined by the equation below based on Mooney viscosities ML (1 +4) at 130° C. measured in accordance with JIS K 6300:2001-1,
Heat aging resistance index (%) =(Mooney viscosity of the modified natural rubber measured after heat treatment at 80° C. for 18 hours)/(Mooney viscosity of the modified natural rubber before the heat treatment)×100.

8. The rubber composition for tires according to claim 1 , wherein the rubber composition contains a silane coupling agent.

9. The rubber composition for tires according to claim 1 , wherein the silica has an average primary particle size of 16 nm or less.

10. The rubber composition for tires according to claim 1 , wherein the modified natural rubber is prepared without mastication.

11. A pneumatic tire formed from the rubber composition according to claim 1 .

12. A pneumatic tire formed from the rubber composition according to claim 2 .

13. A pneumatic tire formed from the rubber composition according to claim 3 .

14. A pneumatic tire formed from the rubber composition according to claim 4 .

15. A pneumatic tire formed from the rubber composition according to claim 5 .

16. A pneumatic tire formed from the rubber composition according to claim 6 .

17. A pneumatic tire formed from the rubber composition according to claim 7 .

Assignees

• Sumitomo Rubber Ind

Inventors

• Sakaki Toshiaki
• YOKOYAMA Yuka
• Hatano Seiji

Classifications

• B60C2011/0016

  Physical properties or dimensions · CPC title

• C08K3/36 Primary

  Silica · CPC title

• B60C1/00

  Tyres characterised by the chemical composition or the physical arrangement or mixture of the composition · CPC title

• C08C1/04

  Purifying; Deproteinising · CPC title

• C08L7/00

  Compositions of natural rubber · CPC title