JPH0657041A - Rubber composition having low heat build-up - Google Patents

Abstract

PURPOSE:To provide a rubber composition having a low heat build-up, improved in heat build-up and usable for a low fuel cost tire by blending a rubber such as natural rubber or diene based rubber with a reinforcing filler and a specific compound such as a benzoquinone compound and a specific compound such as a disulfide compound. CONSTITUTION:The rubber composition having a low heat build-up is obtained by blending (A) 100 pts.wt. rubber consisting of a natural rubber and/or a diene based rubber (e.g. styrene-butadiene rubber) with (B) a reinforcing filler (e.g. carbon black), (C) 0.5-5 pts.wt. one or more kinds of compounds expressed by formula I (R1 to R4 are each H, Cl, 1-4C alkyl, alkoxyl, cyano or phenol), formula II (R5 and R6 are same as R1) and formula III (R7 to R10 are sane as R1), e.g. benzoquinone, naphthoquinone and anthraquinone compounds and (D) 0.1-2 pts.wt. one or more kinds of compounds expressed by formula IV (R11 and R12 are each a 1-4C alkyl or a functional group having a hetero ring of formula V), formula VI (R13 is same as R11), e.g. a disulfide compound or a thiol compound.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low heat-generating rubber composition, and more particularly to a rubber composition mainly used for fuel-efficient tires.

[0002]

2. Description of the Related Art Conventionally, in order to meet social demands for resource saving and energy saving, fuel-efficient tires have been actively developed in the rubber industry, particularly in the tire industry, for the last several years. For the development of such a fuel-efficient tire, development of a low heat-generating rubber composition which is the base of the tire is indispensable. Particularly, regarding a technique for improving a low heat-generating rubber composition by compounding chemicals, JP-A-1-207337 Publication, JP-A-6
The result is provided by Japanese Patent Laid-Open No. 2-184036.

[0003]

This technique is to blend a thiadiazole compound or imidazole dithiocarboxylic acid into the raw material rubber used to obtain a low heat-generating rubber composition. However, in recent years, there has been a further demand for lower fuel consumption of automobiles in order to prevent global warming, and it has been found that the above-mentioned improvement technique using a single compound chemical alone cannot sufficiently meet such demand. Came.

Therefore, in order to further improve the low heat buildup of the rubber, it is possible to synergistically reduce the heat buildup of the rubber by combining two or more compounding agents. It is also a fact that a sufficient effect cannot be obtained by the combination of the property improving agents.

The object of the present invention is to synergistically exhibit a low heat-generating effect by blending natural rubber and / or diene-based synthetic rubber by selectively combining two or more specific compounds. To provide a rubber composition.

[0006]

Means for Solving the Problems As a result of intensive studies made by the present inventors in order to solve the above-mentioned problems, a combination of a specific quinone compound and a specific thiol, monosulfide or disulfide compound is expected to a rubber. The present invention has been completed by confirming that the effect of improving low heat buildup is exhibited.

That is, according to the present invention, 20 to 100 parts by weight of a reinforcing filler, 100 parts by weight of a rubber composed of natural rubber and / or diene rubber, and benzoquinone and naphthoquinone represented by the general formulas of formulas 1 to 3 are used. , 0.5 to 5 parts by weight of at least one compound selected from anthraquinone compounds, and 0.1 to 2 parts by weight of at least one compound selected from compounds represented by Formulas 4 to 5. The present invention relates to a low exothermic rubber composition characterized by the above.

[0008]

[Formula 1]

[0009]

[Formula 2]

[0010]

[Formula 3]

[0011]

[Formula 4]

[0012]

[Formula 5]

In the formula, R _{1 to} R ₁₀ are hydrogen atoms, chlorine atoms,
An alkyl group having 1 to 4 carbon atoms, an alkoxyl group, a cyano group, and a phenyl group. R _{11 to} R ₁₃ are each a hydrogen atom, a hydroxyl group, an ester bond, an ether bond, an alkyl group having 1 to 4 carbon atoms containing a thioether bond, or a heterocycle represented by Formula 6 to Formula 14. It is a functional group having. That is, a thiadiazole group represented by formula 6 to formula 8,
In the thiazole or benzthiazole group represented by the formula 9 or 10, the imidazole or benzimidazole group represented by the formula 11 or 12, the benzene ring represented by the formula 13, or the formula 14 Included are the pyridine rings shown.

[0014]

[Formula 6]

[0015]

[Formula 7]

[0016]

[Formula 8]

[0017]

[Formula 9]

[0018]

[Formula 10]

[0019]

[Formula 11]

[0020]

[Formula 12]

[0021]

[Formula 13]

[0022]

[Formula 14]

[0023]

The raw rubber used in the rubber composition of the present invention is
Natural rubber, styrene-butadiene rubber, butadiene rubber, isoprene rubber and the like are used alone or as a blend thereof.

Specific examples of the compound represented by the formula 1, which is added to the rubber as a compounding agent, include p-benzoquinone, 2,
5-dimethyl-p-benzoquinone, 2,5-di-t-butyl-p-benzoquinone, 2,5-dichloro-p-benzoquinone, 2,6-dimethoxy-p-benzoquinone, 2
-Methyl-p-benzoquinone, t-butylbenzoquinone, tetrachloro-p-benzoquinone, 2,3-dichloro-4,5-dicyano-p-benzoquinone, tetracyanobenzoquinone, chloranilic acid, phenyl-p-benzoquinone and the like. .

Specific examples of the compound represented by the formula 2 are:
4-naphthoquinone, 1,2-naphthoquinone, 2,3-dichloro-1,4-naphthoquinone, 2-methyl-1,4-
Examples thereof include naphthoquinone, hydroxy-1,4-naphthoquinone, dihydroxy-1,4-naphthoquinone and the like.

Specific examples of the compound represented by the formula 3 are anthraquinone, hydroxyanthraquinone, dihydroxyanthraquinone, aminoanthraquinone, diaminoanthraquinone and the like.

Specific examples of the compound represented by the formula 4 include dibenzothiazyl sulfide, 5,5'-dithiobis (1,
3,4-thiadiazole-2-thiol), tetraethylthiuram disulfide, tetrabutylthiuram disulfide, tetramethylthiuram disulfide, tetraisooctylthiuram disulfide and the like.

Specific examples of the compound represented by the formula 5 are 2,
5-dimercapto-1,3,4-thiadiazole, mercaptobenzimidazole, mercaptobenzothiazole, mercaptooxazole, 2-mercaptoethanol, 3-mercapto-2-propanol, 3-mercaptopropanoic acid, 2-mercaptoethyl ether, 2- Examples thereof include mercaptoethyl sulfide, 2-mercapto-5-nitroimidazole, 3-mercapto-1,2-propanediol, 2-mercaptopyridine, mercaptosuccinic acid and mercaptothiazoline.

In the present invention, a compound selected from the formulas 1 to 3 and a compound selected from the formulas 4 and 5 are used together in a predetermined amount with respect to the rubber. In particular, when the compounding amounts of the compounds represented by the formulas 1 to 3 are less than 0.1 parts by weight, respectively, the heat generation improvement of the rubber composition is small, and 5 parts by weight or more and the formula 4, When the amount of the compound represented by the formula 5 exceeds 3 parts by weight, not only the effect of improving the exothermic property of the rubber composition is not further observed, but also the bloom phenomenon is caused and the workability is deteriorated, which is not preferable.

The reinforcing filler compounded in the rubber in the present invention is, for example, various carbon blacks, inorganic fillers represented by silica or calcium carbonate, high styrene resin or cyclized rubber. 20 parts by weight per 100 parts by weight of rubber.
100 parts by weight is used, and among them, 30 parts by weight to 60 parts by weight is preferable, and if it is less than 20 parts by weight, the strength as a rubber is not sufficient, and if it exceeds 100 parts by weight, workability is remarkably impaired. With respect to carbon, the type of carbon is not limited, and low heat generation can be ensured even if the particles are small.

In the rubber composition of the present invention, in addition to the above-mentioned reinforcing filler and heat generation improver, if necessary, a softening agent,
It goes without saying that compounding agents usually used in the rubber industry, such as an antioxidant, a vulcanization accelerator, a vulcanization acceleration aid and a vulcanizing agent, can be appropriately blended.

With respect to the present invention, the inventors of the present invention presume the reduction of heat generation of rubber as follows. That is, the function of the chemical agent for reducing the heat generation of rubber is to connect the polymer and the carbon to improve the carbon dispersion, and the thiol,
Disulfides react with polymers during kneading of rubber to form polymer radicals, while quinones have an action of trapping and stabilizing the polymer radicals, and oxygen radicals or hydroxyl groups at this time act as carbon surface. As a result of having an affinity with, it is considered that the carbon dispersion is improved and the heat of the rubber is reduced.

[0033]

EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples. With the formulation shown in Table 1, various rubber compositions were kneaded and vulcanized using a Banbury mixer to prepare vulcanized rubber samples.

The loss coefficient tan δ was measured using a viscoelasticity measuring device manufactured by Rheometrics Co., Ltd., dynamic strain 1%, frequency 15H.
It was measured under the conditions of z and 60 ° C. The measurement results are shown in Table 1.

Comparative Example 1 is an example in which the compound disclosed in the present invention is not used, and Comparative Examples 2 and 3 are SB.
This is an example of the case where 2,6-di-t-butyl-p-benzoquinone and mercaptobenzothiazole are added alone to R1500. However, it can be seen that in these examples, the effect of improving heat generation is hardly obtained. On the other hand, when 2,6-di-t-butyl-p-benzoquinone and mercaptobenzothiazole were combined in the rubber as in Example 1, 15% or more which could not be obtained by themselves alone was obtained. The effect of improving the exothermic property of was obtained.

The synergistic effect of improving the exothermicity was proved by the butadiene rubber (Comparative Example 4, Example 2) and the natural rubber (Comparative Example 5, Example 3).

Further, as shown in Examples 4, 5, and 6,
If 2,5-dimethyl-p-benzoquinone, 2,3-dichloro-5,6-dicyanobenzoquinone, dihydroxynaphthoquinone, dihydroxyanthraquinone is used instead of 2,6-di-t-butyl-p-benzoquinone, Similarly, a synergistic effect was obtained for the improvement of heat generation.

Further, as shown in Examples 7 and 8, the same synergistic effect was obtained by using dibenzothiazyl sulfide or 2,5-dimercaptobenzothiazole instead of mercaptobenzothiazole.

[0039]

As is clear from the examples and comparative examples,
Rubber made of natural rubber and / or diene-based synthetic rubber,
The rubber composition obtained by using the compound disclosed in the present invention in combination has an effect of improving heat generation, which cannot be obtained by a conventional rubber composition called a so-called low heat-generating rubber. It is extremely useful as a low heat-generating rubber composition in a wide range of fields.

[Table 1]

Claims (1)

[Claims] 1. Reinforcing filler 20 to 100 relative to 100 parts by weight of a rubber composed of natural rubber and / or diene rubber.
Parts by weight, 0.5 to 5 parts by weight of at least one compound selected from benzoquinone, naphthoquinone, and anthraquinone compounds represented by the general formulas of formulas 1 to 3, and compounds represented by formulas 4 to 5 A low exothermic rubber composition, characterized in that 0.1 to 2 parts by weight of at least one compound is blended. [Formula 1] [Formula 2] [Formula 3] [Formula 4] [Formula 5] In the formula, R _{1 to} R ₁₀ are a hydrogen atom, a chlorine atom, and a carbon number of 1 to 4.
Is an alkyl group, an alkoxyl group, a cyano group, or a phenyl group, and R _{11 to} R ₁₃ are each a hydrogen atom, a hydroxyl group, an ester bond, an ether bond, or a thioether bond-containing alkyl group having 1 to 4 carbon atoms, Alternatively, it is a functional group having a heterocycle represented by Formula 6 to Formula 14. [Formula 6] [Formula 7] [Formula 8] [Formula 9] [Formula 10] [Formula 11] [Formula 12] [Formula 13] [Formula 14]