Rubber composition for tires and pneumatic tire

Patent metadata

Field	Value
Publication number	US-9732165-B2
Application number	US-201415100474-A
Country	US
Kind code	B2
Filing date	Nov 27, 2014
Priority date	Dec 26, 2013
Publication date	Aug 15, 2017
Grant date	Aug 15, 2017

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 2-7; carbon black and/or a white filler; and a silane coupling agent represented by the following Formula (S1):

wherein R 1001 represents a monovalent group selected from —Cl, —Br, —OR 1006 , —O(O═)CR 1006 , —ON═CR 1006 R 1007 , —ON═CR 1006 R 1007 , —NR 1006 R 1007 , and —(OSiR 1006 R 1007 ) h (OSiR 1006 R 1007 R 1008 ), wherein R 1006 , R 1007 , and R 1008 are the same as or different from one another and each represent a hydrogen atom or a C1-C18 monovalent hydrocarbon group, and h represents a number whose average value is 1 to 4; R 1002 represents R 1001 , a hydrogen atom, or a C1-C18 monovalent hydrocarbon group; R 1003 represents R 1001 , R 1002 , a hydrogen atom, or the group: —[O(R 1009 O) j ] 0.5 — wherein R 1009 represents a C1-C18 alkylene group, and j represents an integer of 1 to 4; R 1004 represents a C1-C18 divalent hydrocarbon group; R 1005 represents a C1-C18 monovalent hydrocarbon group; and x, y, and Z are numbers satisfying the following relationships: x+y+2z=3, 0≦x≦3, 0≦y≦2, and 0≦z≦1.

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;
at least one of carbon black or a white filler; and
a silane coupling agent represented by the following Formula (S1):

wherein
R 1001 represents a monovalent group selected from —Cl, —Br, —OR 1006 , —O(O═)CR 1006 , —ON═CR 1006 R 1007 , —ON═CR 1006 R 1007 , —NR 1006 R 1007 , and —(OSiR 1006 R 1007 ) h (OSiR 1006 R 1007 R 1008 ), wherein R 1006 , R 1007 , and R 1008 are the same as or different from one another and each represent a hydrogen atom or a C1-C18 monovalent hydrocarbon group, and h represents a number whose average value is 1 to 4;
R 1002 represents R 1001 , a hydrogen atom, or a C1-C18 monovalent hydrocarbon group;
R 1003 represents R 1001 , R 1002 , a hydrogen atom, or the group: —[O(R 1009 O) j ] 0.5 — wherein R 1009 represents a C1-C18 alkylene group, and j represents an integer of 1 to 4;
R 1004 represents a C1-C18 divalent hydrocarbon group;
R 1005 represents a C1-C18 monovalent hydrocarbon group; and x, y, and z are numbers satisfying the following relationships:
x+y+ 2 z= 3,0≦ x≦ 3,0≦ y≦ 2, and 0≦ z≦ 1.

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 white filler is silica.

9. The rubber composition for tires according to claim 1 , comprising styrene-butadiene rubber or polybutadiene rubber.

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 for tires according to claim 1 .

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

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

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

Assignees

• Sumitomo Rubber Ind

Inventors

• Sakaki Toshiaki
• Minagoshi Akira
• YOKOYAMA Yuka

Classifications

• C08L9/06

  Copolymers with styrene · CPC title

• C08L7/00

  Compositions of natural rubber · CPC title

• B60C1/00

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

• C08C1/04 Primary

  Purifying; Deproteinising · CPC title

• B60C11/0008

  characterised by the tread rubber · CPC title