Bead filler rubber composition and pneumatic tire

Patent metadata

Field	Value
Publication number	US-9637618-B2
Application number	US-201415311404-A
Country	US
Kind code	B2
Filing date	Dec 19, 2014
Priority date	May 16, 2014
Publication date	May 2, 2017
Grant date	May 2, 2017

Abstract

A rubber composition for a bead filler contains a diene rubber, a carbon black and a nitrone compound having a carboxy group; the diene rubber contains a natural rubber and a styrene-butadiene rubber, wherein the content of the natural rubber in a total of the diene rubber and the nitrone compound is not less than 60 mass %, and the content of the styrene-butadiene rubber in a total of the diene rubber and the nitrone compound is not greater than 40 mass %; the content of the carbon black is 40 to 80 parts by mass per 100 parts by mass of a total of the diene rubber and the nitrone compound; and the content of the nitrone compound is 0.1 to 10 parts by mass per 100 parts by mass of a total of the diene rubber and the nitrone compound. Such rubber composition exhibits low heat build-up after vulcanization.

First claim

The invention claimed is:

1. A rubber composition for a bead filler, the rubber composition comprising:
a diene rubber;
a carbon black; and
a nitrone compound having a carboxy group;
the diene rubber comprising a natural rubber and a styrene-butadiene rubber, wherein a content of the natural rubber in a total of the diene rubber and the nitrone compound is not less than 60 mass %, and a content of the styrene-butadiene rubber in a total of the diene rubber and the nitrone compound is not greater than 40 mass %;
a content of the carbon black being from 40 to 80 parts by mass per 100 parts by mass of a total of the diene rubber and the nitrone compound; and
a content of the nitrone compound being from 0.1 to 10 parts by mass per 100 parts by mass of a total of the diene rubber and the nitrone compound.

2. A rubber composition for a bead filler, the rubber composition comprising:
a diene rubber; and
a carbon black;
the diene rubber comprising a natural rubber and a modified styrene-butadiene rubber, wherein the modified styrene-butadiene rubber is obtained by a reaction of a nitrone compound having a carboxy group with a double bond of a styrene-butadiene rubber;
a content of the natural rubber in the diene rubber being not less than 60 mass %;
an amount of the styrene-butadiene rubber used for synthesis of the modified styrene-butadiene rubber being not greater than 40 mass % with respect to the diene rubber;
an amount of the nitrone compound used for synthesis of the modified styrene-butadiene rubber being 0.1 to 10 parts by mass per 100 parts by mass of the diene rubber; and
a content of the carbon black being 40 to 80 parts by mass per 100 parts by mass of the diene rubber.

3. A rubber composition for a bead filler, the rubber composition comprising:
a diene rubber; and
a carbon black;
the diene rubber comprising a natural rubber, a modified styrene-butadiene rubber, and a styrene-butadiene rubber, wherein the modified styrene-butadiene rubber is obtained by a reaction of a nitrone compound having a carboxy group with a double bond of a styrene-butadiene rubber;
a content of the natural rubber in the diene rubber being not less than 60 mass %;
a total amount of the styrene-butadiene rubber used for synthesis of the modified styrene-butadiene rubber and the styrene-butadiene rubber in the diene rubber being not greater than 40 mass % with respect to the diene rubber;
an amount of the nitrone compound used for synthesis of the modified styrene-butadiene rubber being 0.1 to 10 parts by mass per 100 parts by mass of the diene rubber; and
a content of the carbon black being 40 to 80 parts by mass per 100 parts by mass of the diene rubber.

4. The rubber composition for a bead filler according to claim 2 , wherein a degree of modification of the modified styrene-butadiene rubber is from 0.02 to 4.0 mol %, wherein “degree of modification” refers to a proportion (mol %) of double bonds modified with the nitrone compound relative to all the double bonds attributed to butadiene in styrene-butadiene rubber.

5. The rubber composition for a bead filler according to claim 1 , wherein a styrene unit content of the styrene-butadiene rubber is not less than 10 mass %.

6. The rubber composition for a bead filler according to claim 1 , wherein the nitrone compound is a compound selected from the group consisting of N-phenyl-α-(4-carboxyphenyl)nitrone, N-phenyl-α-(3-carboxyphenyl)nitrone, N-phenyl-α-(2-carboxyphenyl)nitrone, N-(4-carboxyphenyl)-α-phenylnitrone, N-(3-carboxyphenyl)-α-phenylnitrone, and N-(2-carboxyphenyl)-α-phenylnitrone.

7. The rubber composition for a bead filler according to claim 1 , wherein a nitrogen adsorption specific surface area of the carbon black is from 40 to 150 m 2 /g.

8. A pneumatic tire wherein the rubber composition for a bead filler described in claim 1 is used.

9. The rubber composition for a bead filler according to claim 3 , wherein a degree of modification of the modified styrene-butadiene rubber is from 0.02 to 4.0 mol %, wherein “degree of modification” refers to a proportion (mol %) of double bonds modified with the nitrone compound relative to all the double bonds attributed to butadiene in styrene-butadiene rubber.

10. The rubber composition for a bead filler according to claim 2 , wherein a styrene unit content of the styrene-butadiene rubber is not less than 10 mass %.

11. The rubber composition for a bead filler according to claim 3 , wherein a styrene unit content of the styrene-butadiene rubber is not less than 10 mass %.

12. The rubber composition for a bead filler according to claim 4 , wherein a styrene unit content of the styrene-butadiene rubber is not less than 10 mass %.

13. The rubber composition for a bead filler according to claim 9 , wherein a styrene unit content of the styrene-butadiene rubber is not less than 10 mass %.

14. The rubber composition for a bead filler according to claim 2 , wherein the nitrone compound is a compound selected from the group consisting of N-phenyl-α-(4-carboxyphenyl)nitrone, N-phenyl-α-(3-carboxyphenyl)nitrone, N-phenyl-α-(2-carboxyphenyl)nitrone, N-(4-carboxyphenyl)-α-phenylnitrone, N-(3-carboxyphenyl)-α-phenylnitrone, and N-(2-carboxyphenyl)-α-phenylnitrone.

15. The rubber composition for a bead filler according to claim 3 , wherein the nitrone compound is a compound selected from the group consisting of N-phenyl-α-(4-carboxyphenyl)nitrone, N-phenyl-α-(3-carboxyphenyl)nitrone, N-phenyl-α-(2-carboxyphenyl)nitrone, N-(4-carboxyphenyl)-α-phenylnitrone, N-(3-carboxyphenyl)-α-phenylnitrone, and N-(2-carboxyphenyl)-α-phenylnitrone.

16. The rubber composition for a bead filler according to claim 4 , wherein the nitrone compound is a compound selected from the group consisting of N-phenyl-α-(4-carboxyphenyl)nitrone, N-phenyl-α-(3-carboxyphenyl)nitrone, N-phenyl-α-(2-carboxyphenyl)nitrone, N-(4-carboxyphenyl)-α-phenylnitrone, N-(3-carboxyphenyl)-α-phenylnitrone, and N-(2-carboxyphenyl)-α-phenylnitrone.

17. The rubber composition for a bead filler according to claim 5 , wherein the nitrone compound is a compound selected from the group consisting of N-phenyl-α-(4-carboxyphenyl)nitrone, N-phenyl-α-(3-carboxyphenyl)nitrone, N-phenyl-α-(2-carboxyphenyl)nitrone, N-(4-carboxyphenyl)-α-phenylnitrone, N-(3-carboxyphenyl)-α-phenylnitrone, and N-(2-carboxyphenyl)-α-phenylnitrone.

18. The rubber composition for a bead filler according to claim 9 , wherein the nitrone compound is a compound selected from the group consisting of N-phenyl-α-(4-carboxyphenyl)nitrone, N-phenyl-α-(3-carboxyphenyl)nitrone, N-phenyl-α-(2-carboxyphenyl)nitrone, N-(4-carboxyphenyl)-α-phenylnitrone, N-(3-carboxyphenyl)-α-phenylnitrone, and N-(2-carboxyphenyl)-α-phenylnitrone.

19. The rubber composition for a bead filler according to claim 10 , wherein the nitrone compound is a compound selected from the group consisting of N-phenyl-α-(4-carboxyphenyl)nitrone, N-phenyl-α-(3-carboxyphenyl)nitrone, N-phenyl-α-(2-carboxyphenyl)nitrone, N-(4-carboxyphenyl)-α-phenylnitrone, N-(3-carboxyphenyl)-α-phenylnitrone, and N-(2-carboxyphenyl)-α-phenylnitrone.

20. The rubber composition for a bead filler according to claim 11 , wherein the nitrone compound is a compound selected from the group consisting of N-phenyl-α-(4-carboxyphenyl)nitrone, N-phenyl-α-(3-carboxyphenyl)nitrone, N-phenyl-α-(2-carboxyphenyl)nitrone, N-(4-carboxyphenyl)-α-phenylnitrone, N-(3-carboxyphenyl)-α-phenylnitrone, and N-(2-carboxyphenyl)-α-phenylnitrone.

Assignees

• Yokohama Rubber Co Ltd

Inventors

• Kato Manabu
• Takahashi Ryota
• Okamatsu Takahiro
• Kirino Yoshiaki

Classifications

• B60C2001/005

  Compositions of the bead portions, e.g. clinch or chafer rubber or cushion rubber · CPC title

• C08L7/00 Primary

  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

• C08L2205/03

  containing three or more polymers in a blend · CPC title

• C08L15/00

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