JP2000248115A - Rubber composition and pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a rubber composition which can give a pneumatic tire which can exhibit a marked antislip effect on a wet road surface and improved wet skid performances by compounding a rubber component with silica and phenylenebismaleimide. SOLUTION: This composition desirably comprises 100 pts.wt. rubber component comprising at least either one of natural rubber or synthetic rubber, 5-60 pts.wt. silica, and 0.5-4 pts.wt. phenylenebismaleimide. The rubber component is exemplified by a natural rubber, styrene/butadiene copolymer rubber, butadiene rubber or isoprene rubber and desirably comprises at least 50 wt.% styrene/ butadiene copolymer rubber, especially, emulsion-polymerized styrene/butadiene copolymer. The rubber composition is used as a tread rubber. It is desirable that the rubber composition has a dynamic storage modulus (E') of 7.0-16.0 MPa and a tensile stress at a 300% elongation (M300) of 7.0-15.0 MPa.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for improving wet skid performance among wet road surfaces.

[0002]

2. Description of the Related Art Among various road surface conditions, a wet road surface on a rainy day is slippery and driving of a car is dangerous. Also,
Recently, there has been a movement to regulate the braking distance, and wet skid property has become increasingly important. by the way,
As a conventional technique for improving wet skid properties, the Tg of a polymer is shifted to a high temperature side, and tanδ
(0 ° C.) or a method of improving wettability by blending silica. However, in the former method of increasing tan δ, it is difficult to achieve compatibility with other performances such as dry skid property and low rolling resistance. In the latter method in which silica is blended, the lock μ (when the tire is 100% locked completely
There is an inconvenience that the coefficient of friction when sliding is not improved.

[0003]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned disadvantages, and has an object to solve the problem on a wet road surface having an extremely low friction coefficient.
An object of the present invention is to provide a rubber composition exhibiting a remarkable anti-slip effect and improving wet skid performance, and a pneumatic tire using the same in a tread.

[0004]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that the above object can be achieved by blending phenylenebismaleimide, which is known as a rubber crosslinking agent, in combination with silica. Was completed. The configuration of the present invention is as follows. (1) The rubber composition of the present invention is characterized by comprising a rubber component composed of at least one of a natural rubber and a synthetic rubber, silica and phenylene bismaleimide. In the rubber composition, the rubber component 100
It is preferable that silica is 5 to 60 parts by weight and phenylene bismaleimide is 0.5 to 4 parts by weight with respect to parts by weight. The dynamic storage modulus (E ′) of the rubber composition is preferably 7.0 to 16.0 MPa, and the tensile stress (M ₃₀₀ ) at 300% elongation is preferably 7.0 to 15.0 MPa. Further, the rubber component preferably contains 50% by weight or more of a styrene / butadiene copolymer rubber, preferably an emulsion-polymerized styrene / butadiene copolymer. (2) The pneumatic tire of the present invention is characterized in that the rubber composition is used as a tread rubber.

[0005]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in detail. In the present invention, the rubber component is not particularly limited, and examples thereof include natural rubber, styrene / butadiene copolymer rubber, butadiene rubber, isoprene rubber, and the like. Emulsion-polymerized styrene-butadiene copolymer rubber (E-SBR) can be used. When it is used, it is preferable in terms of abrasion resistance, and when it contains 50% by weight or more of the styrene / butadiene copolymer rubber in the rubber component, it is preferable in terms of dry grip.

The amount of silica is from 5 to 60 parts by weight based on 100 parts by weight of the rubber component. If the amount is less than 5 parts by weight, the dry gripping property tends to decrease and exceeds 60 parts by weight. This is because workability tends to decrease. The amount of phenylene bismaleimide is 0.5 to 4 parts by weight with respect to 100 parts by weight of the rubber component. If it exceeds the part, it tends to be too hard,
It is also costly.

Further, the dynamic storage elastic modulus (E ') of the rubber composition is preferably from 7.0 to 16.0 MPa. If the dynamic storage modulus (E') is less than 7.0 MPa, the feeling of rigidity is insufficient.
This is because if it exceeds 16.0 MPa, the riding comfort tends to decrease. Similarly, it is preferable that the tensile stress (M ₃₀₀ ) at 300% elongation is 7.0 to 15.0 MPa. However, if the tensile stress is less than 7.0 MPa, a feeling of rigidity is insufficient,
This is because if it exceeds 15.0 MPa, the riding comfort tends to decrease.

When the rubber composition having excellent physical properties as described above of the present invention is applied to a tread, the contact pressure distribution of the tire can be made uniform, which greatly contributes to improvement of wet skid property. In the present invention, carbon black can be further added to the rubber composition, and the grade thereof can be a commonly used grade.
SAF, SAF and the like can be exemplified. In the present invention, in addition to the above components, various additives commonly used, for example, a vulcanizing agent, a vulcanization accelerator, a vulcanization accelerator, an antioxidant, an ozone deterioration inhibitor, an antioxidant, a process oil, Zinc oxide, stearic acid, a silane coupling agent and the like can be appropriately compounded.

In the pneumatic tire of the present invention, the above rubber composition is used for a tread rubber, but the structure of the tread is not particularly limited, and the tread has a single-layer rubber structure, a cap rubber layer / base. The present invention can be applied to a two-layer structure of a rubber layer and a multilayer structure, and in any case, it is effective to arrange the rubber composition of the present invention on the tread side.

[0010]

EXAMPLE A rubber composition having the composition shown in Table 1 was prepared in accordance with a conventional method, and the hardness, dynamic storage modulus (E ') and dynamic storage modulus (E') were determined by the following test method using a vulcanized test piece. 30
The tensile stress ( _M300 ) at 0% elongation was measured, and the results are also shown in Table 1. On the other hand, each of the rubber compositions was applied to a tread having a single layer structure, and a test tire (175
/ 65R14), and the wet skid property was measured by the following method. The results are shown in Table 1.

(1) Hardness A hardness test (A type) was carried out in accordance with JIS K6301. (2) Dynamic storage elastic modulus (E ′) Using a viscoelastic spectrometer, an ambient temperature of 25 ° C.
The measurement was performed under the conditions of a frequency of 52 Hz, an initial strain of 5%, and a dynamic strain of 1.0%. (3) Tensile stress (M ₃₀₀₎ in conformity with JIS K6301 (3 type No. specimen) was measured at room temperature, a tensile speed of 500 mm / min conditions. (4) Wet skid property Each test tire was used to run on an actual vehicle on a test course on a wet road by spraying water, and the tires of the comparative examples were evaluated at the following levels. +1: The degree that the difference is seen by the professional driver +2: The degree that the difference is seen by the general driver

[0012]

[Table 1]

[0013] From the test results, in the embodiment, E 'and M ₃₀₀
(Large deformation modulus) can be optimized, and the contact pressure distribution of the tire on a wet road surface with a low friction coefficient is made uniform, and the wet skid property is improved.

[0014]

According to the present invention, it is possible to improve wet skid performance on a slippery wet road while maintaining other performances.

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Claims (6)

[Claims] 1. A rubber composition comprising a rubber component comprising at least one of a natural rubber and a synthetic rubber, silica and phenylene bismaleimide. 2. The rubber composition according to claim 1, wherein silica is 5 to 60 parts by weight and phenylene bismaleimide is 0.5 to 4 parts by weight based on 100 parts by weight of the rubber component. . 3. A dynamic storage modulus (E ′) of 7.0 to 1
6.0 MPa, and the tensile stress (M
The rubber composition according to claim 1 or 2, wherein ( ₃₀₀ ) is from 7.0 to 15.0 MPa. 4. The rubber composition according to claim 1, wherein the rubber component contains at least 50% by weight of a styrene / butadiene copolymer rubber. 5. The rubber composition according to claim 1, wherein the styrene / butadiene copolymer rubber is obtained by emulsion polymerization. 6. A pneumatic tire using the rubber composition according to any one of claims 1 to 5 as a tread rubber.