KR100548149B1 - Rubber composition for tire tread - Google Patents

Abstract

The present invention provides a tire tread rubber composition comprising a dithio phosphate sulfide-based accelerator represented by the following formula (1) as an accelerator in a tire tread rubber composition comprising silica as a reinforcing agent and a silane coupling agent. In the case of a rubber composition in which dithio phosphate sulfide is used as a reinforcing agent and a dithio phosphate sulfide is used as a reinforcing agent, the curing time is induced when the crosslinking of the rubber induces mono and disulfide bonds, which are stronger than conventional TMTD (Teramethyl thiuram monosulfide). It is useful as a tire tread rubber because it can shorten and improve wear resistance and low fuel consumption.

Wherein R ₁ and R ₂ are the same as or different from each other and are an alkyl group having 1 to 12 carbon atoms, and x is an integer of 1 to 2;

Description

Tire composition for tire tread

The present invention relates to a tire tread rubber composition, and more particularly, to a tire tread rubber composition using a dithio phosphate sulfide-based accelerator as an accelerator in a composition containing silica as a reinforcing agent.

The use of silica as a reinforcing agent in place of carbon black has been suggested as a solution in order to simultaneously improve properties such as low fuel efficiency and braking performance of tires, and compositions using the same have been actively researched and developed.

By the way, since silica contains many hydroxyl groups which are typical hydrophilic groups, since compatibility with hydrophobic rubber is inferior, silica aggregates in rubber. Due to this interaction, the bond between the reinforcing agent and rubber during dispersion and mixing of the silica is much lower than the theoretical value, which causes the limiting of the reinforcement of the silica.

In order to solve this problem, rubber compositions using silica as a reinforcing agent are used to couple the hydrophobic silica and induce chemical bonding with rubber.

Rubber compositions using silica have the disadvantage of being difficult to process and have long vulcanization time. This is solved by using a super accelerator such as TMTD (Teramethyl thiuram monosulfide).

However, TMTD reacts with the silane coupling agent to not only reduce the actual amount of accelerator, but also to reduce the effectiveness of the coupling agent, which reduces the number of chemical bonds between silica and rubber, which impairs tire performance such as low fuel consumption and wear characteristics. There is a problem that causes, TMTD has a methyl group as a substituent, there is also an environmental problem that can generate nitrosoamine.

Accordingly, the present invention is to solve the problem in using TMTD as a super-promoter, by using a dithio phosphate sulfide-based accelerator having an alkyl substituent to minimize the reaction with the silane coupling agent to shorten the cure time and rubber It is an object of the present invention to provide a tire tread rubber composition capable of improving low fuel efficiency and wear characteristics by inducing mono and disulfide bonds, which are strong bonds upon crosslinking.

The tire tread rubber composition of the present invention for achieving the above object comprises a silica as a reinforcing agent and a silane coupling agent in the raw material rubber, wherein the promoter is a dithio phosphate sulfide-based accelerator represented by the following formula (1) It is characterized in that it comprises 0.1 to 3 parts by weight based on 100 parts by weight of rubber.                         

Formula 1

Wherein R ₁ and R ₂ are the same as or different from each other and are an alkyl group having 1 to 12 carbon atoms, and x is an integer of 1 to 2;

The present invention will be described in more detail as follows.

The present invention relates to a tire tread rubber composition, wherein the raw material rubber is a diene polymer used in a conventional tire tread rubber composition, and is not particularly limited.

The tire tread rubber composition of the present invention uses silica as a reinforcing agent, and its content is usually about 20 to 90 parts by weight based on 100 parts by weight of the raw material rubber.

In addition, since the silane coupling agent is included, the content thereof is generally preferably 5 to 20 parts by weight based on 100 parts by weight of the reinforcing agent.

As a method for solving the problem of workability by using silica as a reinforcing agent and minimizing the reaction with the silane coupling agent, in the present invention, a dithio phosphate sulfide-based accelerator represented by Chemical Formula 1 is used. When used, it is possible to minimize the reaction with the silane coupling agent to shorten the vulcanization time and induce mono- and disulfide bonds, which are strong bonds during vulcanization, and ultimately improve low fuel efficiency and aging characteristics.

It contains 0.1 to 3 parts by weight of the dithio phosphate sulfide-based accelerator which plays such a role with respect to 100 parts by weight of the raw material rubber. If the content is less than 0.1 part by weight based on 100 parts by weight of the raw material rubber, the effect of the addition is insignificant. If more than 3 parts by weight there may be a problem that increases the risk of scorch.

In addition, the tire tread rubber composition of the present invention includes sulfur as a vulcanizing agent, zinc oxide as a vulcanizing agent, stearic acid, aromatic oil as a softening agent, N-cyclohexyl-2-benzothiazyl sulfenamide as a vulcanizing accelerator, diphenyl guanidine and an antioxidant. Of course it can include.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited by the Examples.

Examples 1 to 3 and Comparative Example 1

Next, a rubber composition was prepared by mixing the compounding agent in a half-barrier mixer at a temperature of 150 ° C. to prepare a rubber composition. The unvulcanized physical properties and the obtained rubber specimens were vulcanized at 160 ° C. for physical property tests. In Table 1, a unit is PHR.

In the property test method, abrasion degree is a rambon abrasion degree, which means the loss of rubber worn by rotating at a sliding ratio of 25% and a load of 1.5 kg at room temperature. The smaller the value, the better the wear performance. 60 ° C tan δ is a measure of rotational resistance at 60 ° C, and the lower the value, the better the low fuel efficiency. Physical property test results are shown in Table 2 below.

Comparative Example 1 Example 1 Example 2 Example 3 S-SBR 75.00 75.00 75.00 75.00 BR 25.00 25.00 25.00 25.00 Silica 80.00 80.00 80.00 80.00 Silane Coupling Agent (TESPT) 7.00 7.00 7.00 7.00 Softener 35.00 35.00 35.00 35.00 Zinc oxide 3.00 3.00 3.00 3.00 Stearic acid 1.00 1.00 1.00 1.00 Antioxidant (6C) 2.50 2.50 2.50 2.50 DPG 1.50 1.50 1.50 1.50 brimstone 1.10 1.10 1.10 1.10 CBS 2.00 2.00 2.00 2.00 TMTD 0.20 - - - Dithiophosphate sulfide - 0.12 0.16 0.20 Co., Ltd. S-SBR: Solution polymerization styrene-butadiene rubber with glass transition temperature of -20 ℃ BR: Butadiene rubber with glass transition temperature of -106 ℃ Silica: Ultra 7000Gr (product of Degussa AG), TESPT: Si69 (product of Degussa) Antioxidant (6C): N-1,3-dimethylbutyl-N-phenyl-p-phenylenediamine DPG: diphenyleneguanidine CBS: N-cyclohexyl-2-benzothiazyl sulfenamide TMTD: Teramethyl thiuram monosulfide dty Pentaphosphate sulfide: In formula (1), R ₁ and R ₂ are alkyl groups having 1 to 12 carbon atoms, and x is an integer of 1 to 2 dithiophosphoric acid sulfide-based promoter

Comparative Example 1 Example 1 Example 2 Example 3 Rush time (t90) 14.2 14.0 12.5 11.2 300% modulus 97 99 106 113 Wear (g) 0.41 0.39 0.37 0.32 60 ℃ tanδ 0.148 0.142 0.137 0.129

From the results in Table 2, it can be seen that the vulcanization time is significantly shortened in the case of the example compared to the comparative example, 300% modulus, wear degree and 60 ℃ tan δ is superior to the comparative example. In addition, when the dithio phosphate sulfide of the present invention is used, it is possible to use a smaller amount of accelerator than the comparative example, and it is possible to shorten the vulcanization time according to the increase in the amount of use and to improve the wear resistance and low fuel consumption.

As described in detail above, in the case of a rubber composition in which dithio phosphate sulfide is introduced as a super accelerator while using silica as a reinforcing agent according to the present invention, it is possible to induce mono and disulfide bonds, which are strong bonds when crosslinking rubber, It is useful as a tire tread rubber because it can shorten vulcanization time and improve abrasion resistance and low fuel consumption when using TMTD.

Claims (2)

A tire tread rubber composition comprising silica as a reinforcing agent and a silane coupling agent in a raw material rubber, A tire tread rubber composition comprising a dithio phosphate sulfide-based accelerator represented by the following formula (1) as an accelerator in an amount of 0.1 to 3 parts by weight based on 100 parts by weight of the raw material rubber. Formula 1

Wherein R ₁ and R ₂ are the same as or different from each other and are an alkyl group having 1 to 12 carbon atoms, and x is an integer of 1 to 2; The tire tread rubber composition according to claim 1, comprising at least one additive selected from a vulcanizing agent, a vulcanizing agent, a softening agent, a vulcanizing accelerator and an anti-aging agent.