JP2001026669A - Tire rubber composition and pneumatic tire using the composition in breaker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inhibit the variation with time against heat by inhibiting the reversion of a breaker formulation to retain heat generation durability and to reduce the damage of breakers, especially the destruction between breakers by increasing hardness and reinforcement and suppressing mechanical fatigue. SOLUTION: A rubber composition which comprises 100 pts.wt. rubber component mainly having a natural rubber and/or an isoprene rubber, 50-80 pts.wt. carbon black, and 0.3-1.5 pts.wt. N,N'-m-xylene-biscitraconimide is used for the breaker formulation, and a tire rubber composition having a hardness of 65-85 and a complex elastic modulus of at least 7.0 MPa is used for breakers.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber composition for a tire, and more particularly to a rubber composition for a tire in which the heat generation durability of rubber which causes breaker damage is improved, and a pneumatic tire using the composition.

[0002]

2. Description of the Related Art A breaker rubber of a tire has a high temperature due to repeated deformation during the running of the tire and becomes high temperature, and the rubber and the breaker cord are peeled off due to repeated stress distortion. In particular, a steel cord or aramid having high rigidity is frequently used for a breaker cord, but the step of the rigidity at the interface between the rubber and the cord is remarkable, and stress strain is concentrated at both ends of the cord, and the rubber and the cord are remarkably separated.

[0003] Conventionally, there is a method of increasing the hardness of the breaker rubber to suppress the deformation of the tire during running and reduce the mechanical fatigue. However, in order to increase the hardness, it is necessary to use a compound that generates high heat. Therefore, damage due to heat generated by the breaker rubber cannot be prevented. On the other hand, when the composition suppresses heat generation, the hardness becomes low, and the reinforcing property of the breaker is not sufficient, resulting in mechanical fatigue.

[0004] In order to prevent re-vulcanization due to heat generation of the rubber composition and to improve heat durability, Japanese Patent Application Laid-Open Publication No. Hei.
02150, Tokio Hei 6-502208, Tokio Hei 7-50
6606 and JP-A-9-328574.

[0005]

SUMMARY OF THE INVENTION The present invention provides a rubber for tires which enhances reinforcement and reduces mechanical fatigue while maintaining the heat durability of the breaker rubber, thereby preventing breaker damage and reducing road noise. Provided are a composition and a pneumatic tire using the composition in a breaker.

[0006]

According to the present invention, there is provided a rubber component comprising at least 80 parts by weight of natural rubber and / or isoprene rubber.
50 to 80 parts by weight of carbon black and 0.3 to 1.5 parts by weight of N, N'-m-xylene-bis-citraconimide are added to the mixture of the JIS A hardness of 6 parts by weight.
It is a rubber composition for tires having a complex elastic modulus E * of at least 7.0 Mpa under the conditions of 5 to 85, a temperature of 70 ° C., an initial strain of 10%, a dynamic strain of ± 2%, and a frequency of 10 Hz. Preferably, the carbon black has a specific surface area N ₂ SA of 80 m ² / g or more by a nitrogen adsorption method. A pneumatic tire using the rubber composition for a breaker.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.

First, the rubber component used in the rubber composition of the present invention must contain at least 80 parts by weight of natural rubber and / or isoprene rubber from the viewpoint of low heat build-up. However, other rubber components such as polybutadiene rubber, styrene-butadiene rubber, butyl rubber, EPDM
And the like. In the present invention, a rubber composition preferably containing 100 parts by weight of natural rubber and / or isoprene rubber as a rubber component.

Next, 50 to 80 parts by weight of carbon black is mixed with 100 parts by weight of the rubber component. If the amount is less than 50 parts by weight, sufficient reinforcing properties cannot be obtained after vulcanization of the rubber composition. If the amount exceeds 80 parts by weight, heat generation will increase. Preferably it is 60 to 75 parts by weight.

When the carbon black has a specific surface area N ₂ SA of 80 m ² / g or more by the nitrogen adsorption method, the effect of reinforcing the vulcanized rubber is further improved.

Next, N, N'-m-xylene-bis-citraconimide is used in an amount of 0.3 to 0.3 parts by weight based on 100 parts by weight of the rubber component.
1.5 parts by weight are blended. If it is less than 0.3, heat deterioration due to heat generation cannot be prevented, and the rubber reinforcing effect is not sufficient, while if it exceeds 1.5 parts by weight, it is hard and the tear strength decreases,
Separation from the breaker cord due to deformation is likely to occur.

Next, the JIS A hardness of the rubber composition of the present invention is set in the range of 65 to 85. If it is less than 65, the rigidity is not sufficient, while if it exceeds 85, the rigidity becomes too high and when used in a tire breaker, the steering stability is impaired. Preferably, the JIS A hardness is 70 to
The range is 80.

The rubber composition of the present invention must have a complex elastic modulus E * of 7.0 Mpa or more measured at a temperature of 70 ° C., an initial strain of 10%, a dynamic strain of ± 2%, and a frequency of 10 Hz. When a composite is formed by covering a breaker cord with a rubber composition of 7.0 Mpa or more, the entire composite is reinforced and peeling between breaker plies is reduced even under repeated deformation during tire running.

The breaker cord used in the pneumatic tire of the present invention uses not only steel cord but also organic fibers such as aromatic polyamide fiber and polyester fiber.

[0015]

EXAMPLES Examples and comparative examples of the present invention will be specifically described below.

Various rubber compositions shown in Table 2 were prepared using the basic formulations shown in Table 1. Using these rubber compositions, a 195 / 70R15.5 light truck tire was prepared by using the rubber composition for a breaker. The breaker was composed of two layers of steel cord plies.

[0017]

[Table 1]

The performance of the manufactured tire was evaluated by the following method. The measurement results are also described in Table 2.

(1) Complex elastic modulus (E *) The vulcanized rubber was taken out from the tire and measured with a viscoelastic spectrometer manufactured by Iwamoto Seisakusho at a measurement temperature of 70 ° C., an initial strain of 10%, a dynamic strain of ± 2%, and a frequency of 10 Hz. .

(2) Indoor bench durability test The test conditions are as follows.

Internal pressure JATMA MAX load JATMA standard (maximum load) Speed 30 Km / h Slip angle ± 3 degrees Positive time 10 minutes Running time 144 hrs (6 days) After running the tire under the above conditions, the tire is disassembled and separated between breakers. The condition was observed.

(3) Market durability test After running for about one year in the Middle East (completely worn), the tires were collected and dismantled, and the state of separation between breakers was observed.

(4) Noise Measurement Using Comparative Example 1 as a control (0), the difference was measured in overalls. The smaller the value, the lower the noise.

(5) JIS A hardness Measured according to JIS K6253.

[0025]

[Table 2]

When the rubber composition of the present invention is used for a breaker rubber, the breakers in Examples 1 to 3 do not cause breaker damage and the noise can be kept at a low level as compared with Comparative Examples 1 to 3.

The embodiments disclosed this time are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

[0028]

When the rubber composition of the present invention is used in a breaker of a pneumatic tire, delamination of the breaker can be reduced and the noise level of the tire can be reduced.

Claims (3)

[Claims] 1. A rubber component containing 80 parts by weight or more of natural rubber and / or isoprene rubber, 50 to 80 parts by weight of carbon black and 0,0 parts by weight of N, N'-m-xylene-bis-citraconimide. 0.3 to 1.5 parts by weight, JIS A hardness is 65 to 85, temperature 7
0 ° C, initial strain 10%, dynamic strain ± 2%, frequency 10Hz
Complex elastic modulus (E *) measured under the condition of 7.0 Mpa
The above rubber composition for a tire. 2. The rubber composition according to claim 1, wherein the carbon black has a specific surface area N ₂ SA of 80 m ² / g or more by a nitrogen adsorption method. 3. A pneumatic tire using the rubber composition according to claim 1 for a breaker.