JPH023437A - Rubber composition of low heat build-up - Google Patents

Abstract

PURPOSE:To obtain the above rubber compsn. having a remarkably improved heat build-up effect by compounding a reinforcing filler and a specified heat build-up modifier to a natural rubber or a diene synthetic rubber. CONSTITUTION:The title rubber compsn. is obtd. by compounding 100 pts.wt. rubber consisting of a natural rubber and/or a diene synthetic rubber with 20-150 pts.wt. reinforcing filler and 0.1-10 pts.wt. one or more members selected from among 2-substd. imidazole compd., phenylenediamine compd. and formaldehyde condensates. The heat build-up modifier to be sued can be easily used by mixing a 2-substd. imidazole compd. and a phenylenediamine compd. in methanol and adding therein formaldehyde at 50-55 deg.C. This modifier can be used alone or two or more thereof can be used. If the loading of the reinforcing filler (e.g., carbon black) is less than 20 pts.wt., the reinforcability of the rubber compsn. is inferior and, if it exceeds 150 pts.wt., it is not pref. because the heat build-up improving effect becomes small and physical characteristics such as wear resistance becomes remarkably inferior.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a low heat generation rubber composition.

[Background Art] In order to meet social demands for resource and energy conservation, the rubber industry, particularly the tire industry, has been actively developing fuel-efficient tires over the past few years. A low heat build-up rubber composition is essential for the development of such fuel-efficient tires.
Publication No.

As described in JP-A-58-36705, there is a method of using styrene-butadiene rubber in which the content of bound styrene and vinyl bonds is controlled; It cannot be applied to rubber, especially natural rubber, which is most widely used in heavy-duty tires.

On the other hand, Japanese Patent Publication No. 50-38131, British Patent Section 1,
No. 185,896, U.S. Patent No. 2°315.85
No. 5 and US Pat. No. 2,315°856, US Pat. No. 2,880,240, and US Pat. No. 3,151,161.

U.S. Pat. Diphenylamine.

N,4-dinitroso-N-methylaniline, N-(2-
It is described that the heat generation properties of rubber compositions are improved by adding methyl-2-'nitropropyl)-4-nitrosoaniline and the like.

However, although such nitroso compounds certainly improve heat generation properties, they have the disadvantage that, especially when applied to polyisoprene rubber, they have a large softening and decomposition effect on the polymer, significantly reducing the abrasion resistance of the rubber composition. have. Furthermore, when the above-mentioned nitroso compound is applied to polyisoprene rubber, it significantly improves the heat generation properties, but when applied to synthetic rubbers, such as styrene-butadiene copolymer rubber and polybutadiene rubber, the effect of improving heat generation properties is not so great. I can't wait. Furthermore, in recent years, the sanitary properties of nitrosamines have become a social issue, making it difficult to use any of these compounds.

[Problems to be Solved by the Invention] As mentioned above, the present invention solves the problems that conventional heat generation improvers cannot be applied to natural rubber, and that when applied to polyisoprene rubber, the softening and decomposition effects are large. Furthermore, the present invention aims to solve the problem that when applied to styrene-butadiene copolymer rubber or polybutadiene rubber, a heat generation improvement effect cannot be expected much, and to provide a low heat generation rubber composition that does not have such drawbacks. It is something.

[Means for Solving the Problems] In order to improve the above-mentioned drawbacks, the inventors have:
The present invention was arrived at as a result of intensive studies on heat generation improvers other than nitroso compounds.

That is, the present invention is comprised of 100 parts by weight of rubber made of natural rubber and/or diene synthetic rubber, 20 to 150 parts by weight of a reinforcing filler, a 2-substituted imidazole compound, a phenylenediamine compound, and a reinforcing filler. 0.1 to 1 of one or more formaldehyde condensates
The present invention relates to a low heat build-up rubber composition characterized in that it contains 0 parts by weight.

Rubbers to which the heat generation improver of the present invention can be applied include natural rubber, polyisoprene rubber, and styrene-butadiene copolymer rubber. Rubbers such as polybutadiene rubber, acrylonitrile-butadiene copolymer rubber, ethylene-propylene-diene copolymer rubber, and isobutylene-isoprene copolymer rubber may be used alone or in a mixture of two or more of these rubbers.

The heat generation improver according to the present invention can be easily obtained by mixing a 2-substituted imidazole compound and a phenylenediamine compound in methanol, and adding formaldehyde to the mixture at 50 to 55°C. For example, when benzimidacylinthione is used as the 2-substituted imidazole compound and p-phenylenediamine is used as the phenylenediamine compound, these reactions are estimated as follows.

However, in the above reaction, a chain may be formed without cyclization. This product and reaction mechanism have not been confirmed.

The 2-substituted imidazole compounds according to the present invention include:
2-Benzimidacilinthione, 5-lupoethoxy-
2-Benzimidacilinthione.

4-Ethyl-2-benzimidacylinthion, 4-methyl-2-benzimidacylinthion, 5-lycol-2-
Benzimidacilinthione, 6-nitro-2-benzimidacylinthion, 4-amino-2-benzimidacylinthion, 4,6-dimethyl-2-benzimidacylinthion, 7-medoxy-2-benzimidacylinthion lynchion, 4,6-dimethyl-7-chloro-2-benzimidacylonthion, 2-benzimidacylon, 5-carboethoxy-2-benzimidacylon, 4-methyl-2-benzimidacylon, 5 -Chlor-2-benzimidacylone, 6-nitro-2-benzimidacylone, 4-amino-
2-Benzimidacilone.

4.6-dimethyl-2-benzimidacylone, 7-medoxy-2-benzimidacylone, 4.6-dimethyl-7
- Chlorou 2-benzimidacylon.

Examples include 4,6-dimethyl-7-chloro-2-benzimidacylon.

In addition, examples of phenylenediamine compounds include 0-phenylenediamine, 1m-phenylenediamine, p-phenylenediamine, 4-aminosifdenylamine, N-cyclohexyl-p-phenylenediamine, N,N'- diphenyl-p-fuynylenediamine, N,N'-diβ-
naphthyl-p-phenylenediamine, 2,3-diaminotoluene, 2,4-diaminotoluene, 2,6-dimethyl-p-phenyldiamine, N,N'-di-5ec-butyl-p-phenylenediamine, N,N″bis(1-methylheptyl)-p-phenylenediamine, N,No-
Bis(1-methyl-3-methylpentyl)-p-phenylenediamine, N,N″-bis(1,4-dimethylpentyl)-p-phenylenediamine, N-isopropyl-
No-phenyl-p-phenylenediamine, N-octyl-No-phenyl-p-phenylenediamine, N.

No-diheptyl-p-phenylenediamine, N-(1
, 3-dimethylbutyl)-No-phenyl-p-phenylenediamine, and the like.

The heat generation improver according to the present invention may be used alone or in combination of two or more kinds, and the blending amount of such heat generation improver is from 0.1 to
It is 10 parts by weight. If it is less than 0.1 part by weight, little effect of improving heat generation in the rubber composition can be expected, and if it is added in an amount of 10 parts by weight or more, the functional properties of the rubber composition will deteriorate, which is not preferable.

In the present invention, the blending amount of the reinforcing filler (carbon black, etc.) is 20 to 150 parts by weight; if it is less than 20 parts by weight, the reinforcing properties of the rubber composition will be poor, and if it exceeds 150 parts by weight, the heat generation property improvement effect will be poor. It is undesirable because it is small and its physical properties such as wear resistance are significantly inferior.

In addition to the above-mentioned reinforcing fillers and heat-generating improvers, the present invention may also contain metal oxides such as zinc white, paraffinic, naphthenic or aromatic processing oils, etc., in the target rubber component. Softeners, various higher fatty acids such as stearic acid, colorants and pigments, anti-aging agents, ultraviolet absorbers, vulcanization accelerators, vulcanization accelerators.

Various compounding agents such as a vulcanizing agent can be added as necessary. The mixture can also be mixed using a conventionally used open roll for kneading rubber, a Banbury mixer, a pressure kneader, or the like.

The rubber composition of the present invention can be applied to all kinds of rubber products such as tires, conveyor belts, hoses, and anti-vibration rubber.

[Example] Hereinafter, the present invention will be explained in detail with reference to Synthesis Examples, Examples, and Comparative Examples, but the present invention is not limited thereto.

Synthesis example 1 Synthesis of condensate I.

2-benzimidacylinthione 30. Og (0.2 mol), 21.6 g (0.2 mol) of p-phenylenediamine and 400 ml of methanol were placed in a 500 ml 400ml colben and placed on a hot water bath equipped with a stirrer, reflux condenser, thermometer and dropping funnel. 32.4 g (0.4 mol) of a 37% formaldehyde solution was added over 30 minutes while stirring and heating the mixture to 50 to 55°C. After stirring at the same temperature for 4 hours,
The product was filtered, washed, and dried. The product was 53.0 g and the yield was 94.0%. Melting point is 253.6-256
．． It was 0°C.

Synthesis example 2 Synthesis of condensate ■.

2-benzimidacylone 20.1 g (0.15 mol),
p-phenylenediamine 16.2g (0.15 mol)
Synthesis was carried out in the same manner as in Synthesis Example 1 using 300 ml of methanol and 24.3 g (0.30 mol) of 37% formaldehyde solution. The product is 35.8g and the yield is 89.7
%Met. The melting point was 259.0-262.0°C.

Synthesis example 3 Synthesis of condensate ■.

2-benzimidacylinthione 15. Og (01 mol)
12.2 g (0.1 mol) of 1m-tolylenediamine,
Synthesis was carried out in the same manner as in Synthesis Example 1 using 200 ml of methanol and 16.2 g (0.2 mol) of 37% formaldehyde solution. The product weighed 26.3 g and the yield was 88.8%.

The melting point was 205.2-208.6°C.

Synthesis Example 4 Synthesis of condensate ① 2-benzimidacylone 13.4g (0.1 mol),
m-) 12.2 g (0° 1 mol) of lylene diamine,
Synthesis was carried out in the same manner as in Synthesis Example 1 using 200 ml of methanol and 16.2 g (0.2 mol) of 37% formaldehyde solution. The product was 233g and the yield was 83.2%.
Met. The melting point was 223.0-226.8°C.

Examples A rubber composition was obtained by mixing in a conventional manner according to the formulation shown in Table 1. JIS K 630 for the vulcanized sample obtained after press vulcanizing the compounded rubber at 145°C for 30 minutes.
1 (vulcanized rubber physical test method), and a heat resistance test was conducted in accordance with ASTM-D-623-58 using a Gudrich-type heat generation tester at a load of 16 kg and a stroke of 6. .35mm, frequency 180Or
, p.

ml, the temperature inside the tank is 40℃, and the exothermic temperature after 40 minutes (
Table 1 shows the results of measuring the rubber temperature (expressed as the difference between the rubber temperature after 40 minutes and the initial rubber temperature).

[Effects of the Invention] As is clear from the above, the rubber composition according to the present invention has a remarkable effect of improving heat generation.

Claims (1)

[Claims] Rubber 1 made of natural rubber and/or diene-based synthetic rubber
00 parts by weight, 20 to 150 parts by weight of reinforcing filler and 2-
1. A low heat generation rubber composition comprising 0.1 to 10 parts by weight of one or more condensates of a substituted imidazole compound, a phenylenediamine compound, and formaldehyde.