JPS63182355A - Rubber composition for tire - Google Patents

Abstract

PURPOSE:To provide the title compsn. which has excellent stability against scorching and resistance to reversion during processing and vulcanization and exhibits excellent thermal aging resistance, high-temperature physical properties and high-speed durability after vulcanization, by blending a rubbery polymer with a specified bismaleimide compd., a triazine compd. and sulfure. CONSTITUTION:100pts.wt. rubbery polymer (A) composed of natural and/or synthetic diene rubber is blended with 0.2-5pts.wt. bismaleimide compd. (B) of formula I [wherein R is phenylene or a group of formula II (wherein n is 2-8)], 0.1-3.0pts.wt. triazine compd. (C) of formula III [wherein R1 is NR'2 (wherein R' is a 2-4C alkyl) or NHR''2 (wherein R'' is R' or phenyl): R2 is SH or a group of formula IV or V; R3 is H or a group of formula VI or VII] and 0.5-5.0pts.wt. sulfur (D).

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a rubber composition for tires with improved rubber physical properties, and in particular, a rubber composition that is stable in scorch and has good reversion resistance during processing and vulcanization steps. The present invention relates to a rubber composition for tires, which has excellent rubber physical properties after vulcanization, such as heat aging resistance, strength at high temperatures, and fracture energy.

(Conventional technology and its problems) In recent years, the usage conditions for rubber products such as tires have become increasingly strict depending on the application, and higher mechanical properties and heat resistance are required than ever before. ing. However, there is no one that fully satisfies these requirements.

Conventionally, as a rubber composition for tires that attempts to solve these demands, there is one proposed in, for example, Japanese Patent Application Laid-Open No. 166844/1984. This is an attempt to improve scorch stability, reversion resistance, heat deterioration resistance, and bending resistance by mixing and blending bismaleimides, sulfenamides, dithiophosphoric acids, and sulfur with rubber. Further, there is a method proposed in Japanese Patent Application Laid-Open No. 168642/1983.

This product contains bismaleimides and aromatic carboxylic acid anhydrides, and provides a rubber composition with excellent reversion resistance and excellent heat deterioration resistance and bending plate deterioration resistance after vulcanization. . These have effects on scorch stability and reversion resistance during the vulcanization process. However, these rubber physical properties after vulcanization do not have sufficient strength and heat aging resistance, especially when applied to parts such as tire parts that require high temperature resistance and high fracture energy when used at high temperatures. For example, the trend rubber and case rubber of high-performance tires and competition tires cannot withstand the rapid temperature rise during high-speed driving, and the rubber decomposes and generates gas, resulting in so-called separation and chunk-outs between the rubber. There is a problem that peeling failure occurs.

There is also a method proposed in Japanese Patent Application Laid-Open No. 58-198545. It has been proposed to use trimercaptotriazine and a compound containing an N-S group in the molecule, such as the following, in combination to improve the strength, elongation, and heat aging resistance of the vulcanizate. This is because when sulfur is used for vulcanization, the mechanical properties such as hardness and modulus of the vulcanized rubber are improved. L7However, this method not only does not have sufficient reversion resistance in the vulcanization process, but also has insufficient heat aging resistance of vulcanized rubber, and when applied to parts that require heat resistance of tires, For example, the tread and case rubber of high-performance tires and competition tires are unable to withstand rapid temperature rises during high-speed driving and continuous high-temperature tire use, resulting in so-called blow-out, which occurs when the rubber decomposes and generates gas. There is a problem in that this causes peeling failures between rubbers such as separation and chunk-outs.

Therefore, the present invention has been developed to prevent rubber peeling failures such as so-called blowouts even when the temperature of the rubber suddenly rises to high temperatures, such as high performance tires and competition tires that require high maneuverability and high-speed durability. It is an object of the present invention to provide a rubber composition for tires that can prevent the occurrence of such problems, has significantly improved heat aging resistance and high-temperature physical properties, and has excellent high-speed durability.

(Means for Solving the Problems) As a result of various studies conducted by the present inventors on rubber members having heat resistance at high temperatures, heat aging resistance, and high fracture energy at high temperatures, the present inventors found that a bismaleimide compound represented by By using a specific triazine compound or a derivative thereof in combination with (In) sulfur, it is possible to obtain excellent reversion resistance and scorch stability, and in particular, to greatly improve heat aging resistance at high temperatures. , high temperature physical properties (
We have discovered a rubber composition that also has improved breaking strength and breaking energy.

The present inventors further conducted intensive research and completed the present invention.

That is, in the rubber assembly for tires according to the present invention, 0.2 to 5 parts by weight of a bismaleimide compound represented by OU is added to 100 parts by weight of a rubbery polymer made of natural rubber and/or diene-based synthetic rubber. , (It) is characterized by blending 0.1 to 3.0 parts by weight of a triazine compound represented by the general formula R1 and 0.5 to 5.0 parts by weight of (I[[) sulfur.

Here, the blending amount of the bismaleimide compound (1) is desirably 0.2 to 5 parts by weight, preferably 0.5 to 3 parts by weight, based on 100 parts by weight of the rubbery polymer. 0.5~5
The reason why it is specified as parts by weight is that if it is less than 0.5 parts by weight, the reversion resistance will not be sufficient, and if it exceeds 5 parts by weight, vulcanization will be delayed and the physical properties of the vulcanized rubber will be unfavorable.

The amount of the triazine compound (II) to be blended is preferably 0.1 to 3.0 parts by weight, preferably 0.1 to 2.0 parts by weight, based on 100 parts by weight of the rubbery polymer. It is 111 parts of O.

The reason why the amount is 0.1 to 3.0 parts by weight is that if it is less than 0.1 parts by weight, the heat resistance will not be sufficient, and if it exceeds 3.0 parts by weight, the scorch stability will be low and it will be easy to scorch.

Further, the amount of sulfur blended is preferably 0.5 to 5.0 parts by weight per 100 parts by weight of the rubbery polymer. 0.5-5.0
The reason for the weight part is that if it is less than 0.5 part by weight, vulcanization will be delayed.
This is because if it exceeds 5.0 parts by weight, heat resistance will decrease.

The rubber composition for tires according to the present invention has the above-mentioned structure, and when a bismaleimide compound, a specific triazine compound, and sulfur are combined in combination with a rubbery polymer, the reaction mechanism is not clear, but it has particularly good high-temperature heat resistance. The surprising finding was that the blowout properties were significantly improved due to a synergistic effect.

Specific examples of bismaleimide compounds used in the present invention include N-N'-m-phenylene bismaleimide and linear methylene bismaleimide, N, N'-
Ethylene bismaleimide and N,N'-hexamethylene bismaleimide with n=6. When using a bismaleimide compound for a case member in which a steel wire is embedded (eg, NIBLY coating rubber), adhesion is important, so it is absolutely necessary to incorporate a linear methylene bismaleimide compound.

Moreover, as specific examples of triazine compounds, there are those shown below.

2-dibutylamino-4,6-dimercapto-S represented by
-Triazine (Triazine DB manufactured by Iriuchi Shinko Kagaku ■), N-(C,H,)! 2,4-bis(benzothiazyl, dithio-6-sibutyl-amino-S-)riazine (triazine DT manufactured by Shinko Iriuchi) represented by triazine AD) manufactured by Kawaguchi Kagaku Jun Co., Ltd., and 2-ethylamino-4-diethylamino-6-triazyl (triazine DB manufactured by Kawaguchi Kagaku Jun Co., Ltd.).

(Examples 1 to 5. Comparative Examples 1 to 5) Hereinafter, the rubber composition for tires according to the present invention will be explained in more detail with reference to Examples and Comparative Examples.

In the following table, for Examples 1 to 5 and Comparative Examples 1 to 5, the contents of the compounding ingredients of tire rubber compositions are shown in the upper row, and the physical properties of each rubber sample were tested using the test method below, and the test results are shown in the lower row. show.

Examples 1 to 3 and Comparative Example 4 used only natural rubber, Example 4 and Comparative Example 5 used natural rubber and diene-based synthetic rubber, and Example 5 used natural rubber and isoprene rubber. Indicate the case. In addition, Comparative Examples 1 to 3 are examples in which only natural rubber is used, Comparative Example 1 is a case where only a bismaleimide compound is blended and no triazine compound is blended, and Comparative Example 2 is a case where only a triazine compound is blended and a bismaleimide compound is blended. This is a case where no compound is blended, and this is an example showing that it is necessary to blend a bismaleimide compound and a triazine compound in combination in order to exhibit the synergistic effect of the present invention. In addition, in Comparative Example 3, the amount of sulfur blended was 1
0.00 parts by weight is limited to 0.5 to 5 parts by weight.

(Test Method) Tests were conducted on the blowout temperature, heat aging resistance, high temperature physical properties, reversion resistance, and scorch stability of each sample.

(1) Blowout temperature: Qo'd-Ric
The temperature at which blowing begins was measured using an h-type flexmeter in accordance with ASTM D623.

(2) Heat aging resistance: The ingredients shown in the table were mixed and vulcanized to prepare a sample of a rubber composition in the form of a sheet with a thickness of 21 mm. These rubber samples were heat aged by being left in an air bath at a temperature of 100°C for 24 hours. The stress and strain characteristics of these heat aged samples were measured based on JIS K6301. For the breaking strength and breaking energy (product of tensile strength T1 at break and elongation E), the measured value of the sample before heat aging was taken as 100, and the properties after heat aging were expressed as retention rates (%). The larger the value, the better.

(3) High-temperature physical properties: As in the case of (2) heat aging resistance described above, a sheet-like rubber composition sample with a thickness of 211 seconds was prepared, and after being left in an open state at a temperature of 120°C for 20 minutes, The stress strain characteristics of these high temperature physical property samples were determined according to JIS K6.
Measured based on 301.

The breaking strength and breaking energy were measured and displayed in the same manner as in the case of heat aging resistance (2) and (7) above.

(4) Heat-resistance reversion property: While heating a sample of the unvulcanized rubber composition of each compound at a temperature of 190°C for 70 minutes using an ordinary curelastometer, the torque F generated on the sample axis after 30 minutes, . The ratio (%) between this and the maximum torque F WAI was measured. The larger the value, the better.

(5) Scorch stability: In accordance with JIS K2SO3, the value t0. which is 50% of the maximum torque value. ．． Time to reach (
minutes) and this time (minutes) was expressed as Mooney's scorch stability. The larger the value, the better.

(This page, blank spaces below) The test results show that, as shown in the lower part of the table above, the rubber compositions of Examples 1 to 5 had better reversion resistance and scorch stability than those of Comparative Examples 1 to 5. is good, and especially,
Heat aging resistance is significantly improved, and a synergistic effect is seen. In addition, blowout properties and high-temperature physical properties are also significantly improved. Therefore, it can be used for tread rubber and case rubber of high-performance tires and competition tires that require heat resistance and high mechanical properties at high temperatures, and can also be used for rubbers that are subject to severe conditions such as bead fillers. Can be done.

In particular, as shown in the comparison between Examples 1 to 3 and Comparative Example 1.2, the rubber composition according to the present invention, which contains a bismaleimide compound and a triazine compound in combination, has the following properties: without impairing the scorch stability. In terms of heat aging resistance, high-temperature physical properties, and blowout properties, unprecedented and surprising synergistic effects are exhibited.

(Effects) As explained above, according to the present invention, even if the temperature of the rubber suddenly rises to a high temperature, such as in high-performance tires and competition tires, occurrence of rubber peeling failure can be prevented. In addition, heat aging resistance and high-temperature physical properties can be significantly improved, and high-speed durability can be significantly improved.

Claims (1)

[Claims] 100 parts by weight of a rubbery polymer made of natural rubber and/or diene-based synthetic rubber contains (I) General formula ▲ Numerical formula, chemical formula, table, etc. ▼ [However, R is a phenylene group or - (CH_2)_n-
(n-2 to 8)] 0.2 to 5 parts by weight of a bismaleimide compound represented by (II) General formula ▲ Numerical formula, chemical formula, table, etc. ' is an alkyl group with C=2 to 4) or -NHR''_2 (R'' is an alkyl group with C=2 to 4 or a phenyl group), R_2 is -SH, ▲There are numerical formulas, chemical formulas, tables, etc.▼ or - N(C_2H_5)_2, R_3 is H, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ or ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼] 0.1 to 3.0 parts by weight of a triazine compound represented by (III) A rubber composition for a tire, characterized in that it contains 0.5 to 5.0 parts by weight of sulfur.