Rubber Composition for Tire Tread, and Pneumatic Tire

Patent metadata

Field	Value
Publication number	US-2016009846-A1
Application number	US-201414770457-A
Country	US
Kind code	A1
Filing date	Feb 25, 2014
Priority date	Feb 25, 2013
Publication date	Jan 14, 2016
Grant date	—

Abstract

The present technology provides a rubber composition containing a diene rubber component containing at least 20 mass % of a modified conjugated diene rubber, a silica, and a silane coupling agent; the modified conjugated diene rubber having at least one modified part and at least one conjugated diene rubber part; the conjugated diene rubber part having a conjugated diene copolymer block and an isoprene block containing from 70 mass % to 100 mass % of isoprene units in each conjugated diene rubber part; the modified part bonding to an end of the conjugated diene rubber part and having a functional group which interacts with the silica; a content of the silica being from 60 to 200 parts by mass per 100 parts by mass of the diene rubber component; the silane coupling agent being a polysiloxane and having a content from 1.0 to 20 mass % of the content of the silica.

First claim

1 . A rubber composition for a tire tread containing a diene rubber component containing at least 20 mass % of a modified conjugated diene rubber, a silica, and a silane coupling agent;
the modified conjugated diene rubber having at least one modified part and at least one conjugated diene rubber part; the conjugated diene rubber part having a conjugated diene copolymer block and an isoprene block containing from 70 mass % to 100 mass % of isoprene units in each conjugated diene rubber part; the modified part bonding to an end of the conjugated diene rubber part; the modified part having a functional group which interacts with the silica; the silane coupling agent being a polysiloxane represented by the following formula (1); a content of the silica being from 60 to 200 parts by mass per 100 parts by mass of the diene rubber component; and a content of the silcane coupling agent being from 1.0 to 20 mass % of the content of the silica.
(A) a (B) b (C) c (D) d (R) e SiO (4-2a-b-c-d-c)/2   (1)

[Formula (1) is an average composition formula, and in formula (1), A is a divalent organic group containing a sulfide group; B is a monovalent hydrocarbon group having from 5 to 10 carbon atoms; C is a hydrolyzable group; D is an organic group containing a mercapto group; R 1 is a monovalent hydrocarbon group having from 1 to 4 carbon atoms; and a to e satisfy the relational expressions 0≦a<1, 0≦b<1, 0<c<3, 0<d<1, 0<e<2, and 0<2a+b+c+d+e<4; however, one of either a or b is not 0.]

2 . The rubber composition for a tire tread according to claim 1 , wherein a is greater than 0 in formula (1).

3 . The rubber composition for a tire tread according to claim 1 , wherein b is greater than 0 in formula (1).

4 . The rubber composition for a tire tread according to claim 1 , wherein the skeleton of the modified part is a polyorganosiloxane.

5 . The rubber composition for a tire tread according to claim 1 , wherein a weight average molecular weight of the polysiloxane represented by formula (1) is from 500 to 2,300.

6 . The rubber composition for a tire tread according to claim 1 , further comprising a terpene resin, wherein an amount of the terpene resin is from 1 to 30 parts by mass per 100 parts by mass of the diene rubber component, and the terpene resin is an aromatic modified terpene resin having a softening point of from 60 to 150° C.

7 . The rubber composition for a tire tread according to claim 1 , wherein a vinyl bond content derived from the isoprene units in the isoprene block is from 5 to 85 mass %.

8 . The rubber composition for a tire tread according to claim 1 , wherein the conjugated diene copolymer block is obtained using a conjugated diene monomer (d1) and an aromatic vinyl monomer;
an aromatic vinyl unit content derived from the aromatic vinyl monomer is from 38 to 48 mass % of the conjugated diene rubber; and a vinyl bond content of the conjugated diene rubber part is from 20 to 35 mol % of the conjugated diene units constituting the conjugated diene rubber part.

9 . The rubber composition for a tire tread according to claim 1 , wherein a weight average molecular weight of the modified conjugated diene rubber is from 1,000 to 3,000,000.

10 . The rubber composition for a tire tread according to claim 1 , wherein the conjugated diene rubber part has a conjugated diene copolymer block on an end other than the end; and
the modified conjugated diene rubber has the isoprene block between the conjugated diene copolymer block and the modified part.

11 . The rubber composition for a tire tread according to claim 10 , wherein a weight average molecular weight of the modified conjugated diene rubber is from 600,000 to 1,000,000.

12 . The rubber composition for a tire tread according to claim 1 , wherein the conjugated diene rubber part has the isoprene block on an end other than the end; and
the modified conjugated diene rubber has the isoprene block between the conjugated diene copolymer block and the modified part.

13 . The rubber composition for a tire tread according to claim 1 , wherein the functional group is at least one selected from the group consisting of an epoxy group and a hydrocarbyloxysilyl group.

14 . A pneumatic tire having tire treads formed using the rubber composition for a tire tread described in claim 1 .

Assignees

• Yokohama Rubber Co Ltd

Inventors

• Sato Masaki
• Mihara Satoshi

Classifications

• B60C1/00

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

• B60C1/0016

  Compositions of the tread · CPC title

• C08L9/06

  Copolymers with styrene · CPC title

• C08C19/25

  Incorporating silicon atoms into the molecule · CPC title

• C08G77/14

  containing silicon bound to oxygen-containing groups · CPC title