Rubber composition and pneumatic tire

Abstract

The rubber composition of the present invention comprises 100 parts by mass of a rubber component (A) comprising 45-75 mass% natural rubber and 25-55 mass% one or more conjugated-diene-based polymersin which the conjugated-diene compound moieties have a combined styrene content of 25% or less, 1-40 parts by mass of an unmodified conjugated-diene-based polymer (B) which has a weight-average molecular weight of 5,000 or higher but less than 40,000 in terms of polystyrene as determined by GPC and in which the conjugated-diene compound moieties have a combined styrene content less than 10% and acombined vinyl content of 20% or higher, and a filler (C), wherein at least one of the conjugated-diene-based polymers contained in the rubber component (A) is a modified conjugated-diene-based polymer. The rubber composition gives tires having further improved on-ice performance and combining excellent on-ice performance with excellent wear resistance.

Description

technical field

[0001] The present invention relates to a rubber composition and a pneumatic tire. Background technique

[0002] Conventionally, studless tires with softened tread rubber have been used as tires capable of running safely even on ice other than normal road surfaces, and it is known that softening the tread rubber improves the ice performance of tires. However, tires with soft tread rubber generally have the problem of poor wear resistance of the tire on ordinary roads, so that there is a trade-off relationship between the performance on ice and the wear resistance of the tire.

[0003] In this regard, in order to provide a rubber composition having an improved coefficient of friction on ice and excellent flexibility at low temperature, wet grip and grip on ice, a rubber composition having a compound selected from natural rubber, isoprene rubber , styrene-butadiene rubber, butadiene rubber and isobutylene-isoprene copolymer in the group consisting of at least ...

Examples

Embodiment 1、3、6～10 and 13 and comparative example 2、4 and 6～8

[0217] Using the mixing formulations shown in Tables 2 to 6, the rubber compositions of Examples and Comparative Examples were prepared by mixing in order of a first mixing step and a final mixing step using an ordinary Banbury mixer. In addition, after the first mixing step is completed, the mixture is first extruded from the Banbury mixer, thereafter the mixture is re-introduced into the Banbury mixer, and the final mixing step is performed. In addition, the maximum temperature of the mixture in the first mixing step was set at 170°C, and the maximum temperature of the rubber composition in the final mixing step was set at 110°C.

Embodiment 2、4、5、11 and 12 and comparative example 1、3 and 5

[0219] Using the mixing formulations shown in Tables 2 to 6, the rubber compositions of Examples and Comparative Examples were prepared by mixing in order of a first mixing step and a final mixing step using an ordinary Banbury mixer. In addition, after the first mixing step is completed, the mixture is first extruded from the Banbury mixer, thereafter the mixture is re-introduced into the Banbury mixer, and the final mixing step is performed. In addition, the maximum temperature of the mixture in the first mixing step was set at 170°C, and the maximum temperature of the rubber composition in the final mixing step was set at 110°C.

[0220]

[0221] The details of each component in Tables 2 to 6 are as follows.

[0222] [rubber component]

[0223] Polybutadiene rubber: high-cis polybutadiene rubber, trade name "UBEPOL 150L", manufactured by Ube Industries, Ltd., bound styrene amount of conjugated diene compound part: 0%)

[0224] Modified polybutadiene rubber 1: Modified p...

Embodiment 1、3、8 and 9 and comparative example 2

[0304] A test tire (tire size 195 / 65R15) was produced in a conventional method by using the rubber composition of each Example and each Comparative Example in a tread. The foaming ratio of the tread of the manufactured tire was calculated according to the above formula (1). Next, for the same tire, the on-ice performance and abrasion resistance were evaluated according to the following methods, and a comprehensive evaluation was additionally obtained from the results of both of them. The results are shown in Tables 2 to 6.

technical field

[0001] The present invention relates to a rubber composition and a pneumatic tire. Background technique

[0002] Conventionally, studless tires with softened tread rubber have been used as tires capable of running safely even on ice other than normal road surfaces, and it is known that softening the tread rubber improves the ice performance of tires. However, tires with soft tread rubber generally have the problem of poor wear resistance of the tire on ordinary roads, so that there is a trade-off relationship between the performance on ice and the wear resistance of the tire.

[0003] In this regard, in order to provide a rubber composition having an improved coefficient of friction on ice and excellent flexibility at low temperature, wet grip and grip on ice, a rubber composition having a compound selected from natural rubber, isoprene rubber , styrene-butadiene rubber, butadiene rubber and isobutylene-isoprene copolymer in the group consisting of at least ...

Examples

Embodiment 1、3、6～10 and 13 and comparative example 2、4 and 6～8

[0217] Using the mixing formulations shown in Tables 2 to 6, the rubber compositions of Examples and Comparative Examples were prepared by mixing in order of a first mixing step and a final mixing step using an ordinary Banbury mixer. In addition, after the first mixing step is completed, the mixture is first extruded from the Banbury mixer, thereafter the mixture is re-introduced into the Banbury mixer, and the final mixing step is performed. In addition, the maximum temperature of the mixture in the first mixing step was set at 170°C, and the maximum temperature of the rubber composition in the final mixing step was set at 110°C.

Embodiment 2、4、5、11 and 12 and comparative example 1、3 and 5

[0219] Using the mixing formulations shown in Tables 2 to 6, the rubber compositions of Examples and Comparative Examples were prepared by mixing in order of a first mixing step and a final mixing step using an ordinary Banbury mixer. In addition, after the first mixing step is completed, the mixture is first extruded from the Banbury mixer, thereafter the mixture is re-introduced into the Banbury mixer, and the final mixing step is performed. In addition, the maximum temperature of the mixture in the first mixing step was set at 170°C, and the maximum temperature of the rubber composition in the final mixing step was set at 110°C.

[0220]

[0221] The details of each component in Tables 2 to 6 are as follows.

[0222] [rubber component]

[0223] Polybutadiene rubber: high-cis polybutadiene rubber, trade name "UBEPOL 150L", manufactured by Ube Industries, Ltd., bound styrene amount of conjugated diene compound part: 0%)

[0224] Modified polybutadiene rubber 1: Modified p...

Embodiment 1、3、8 and 9 and comparative example 2

[0304] A test tire (tire size 195 / 65R15) was produced in a conventional method by using the rubber composition of each Example and each Comparative Example in a tread. The foaming ratio of the tread of the manufactured tire was calculated according to the above formula (1). Next, for the same tire, the on-ice performance and abrasion resistance were evaluated according to the following methods, and a comprehensive evaluation was additionally obtained from the results of both of them. The results are shown in Tables 2 to 6.

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