KR20030015932A - Tread rubber composition improved wet traction - Google Patents

Abstract

PURPOSE: Provided is a tire tread rubber composition excellent in wet traction, which keeps the existing fuel consumption and abrasion performance and can improve running-stability such as the wet traction. CONSTITUTION: The tread rubber composition uses a raw rubber containing: 30-45pts.wt. of an emulsion styrene butadiene rubber containing 20-60% of styrene and having a glass transition temperature of -20 to -30deg.C; 30-45pts.wt. of a solution-polymerized styrene butadiene rubber containing 30-40% of styrene and 30-40% of vinyl and having a glass transition temperature of -30 to -40deg.C, wherein the ratio of the styrene and the vinyl is 1:1; 10-40pts.wt. of a neodymium butadiene rubber containing more than 98% of cis and having a glass transition temperature of -100 to -110deg.C.

Description

Tread rubber composition improved wet traction

The present invention relates to a tread rubber composition having excellent wet traction performance and a tire containing the copper rubber composition.

As vehicle performance is improved and advanced, the demands of consumers for tires, which directly play a role in supporting and moving the vehicle, are diversified, which makes it difficult for tire manufacturers to develop products.

Recently, as the economic situation becomes difficult all over the world, the most important factor among consumers' requirements for tires is economical efficiency, and the demand for environmental friendliness is gradually increasing according to the times. In order to meet consumers' demands for economy and eco-friendliness of tires, we supply low-fuel, high wear-resistant tires by applying silica as a reinforcement or reducing hysteresis loss to tire products on the market. have.

In the rubber composition applied to tires with excellent fuel efficiency and abrasion resistance, raw material rubber has a low glass transition temperature, a high rebound elasticity, a low polymer glass transition temperature (Tg) and a solution polymerization having a high vinyl content of 50% or more. It is common to apply styrene butadiene rubber and improve fuel efficiency by adding silica as a reinforcing agent.

That is, the rubber compositions having low glass transition temperature can relatively reduce the hysteresis loss, lower Tan δ at 70 ° C, and have a smaller friction coefficient, thereby obtaining a tire with improved fuel efficiency and wear performance.

However, low fuel consumption and abrasion resistance tires manufactured with materials that reduce hysteresis loss or have high resilience are inferior in terms of driving stability, such as braking force, requiring sudden braking, driving on rainy roads, and heavy loads. There is a problem that there is always a risk of accident during high-speed driving in the state.

The present invention, while trying to solve the problem of low driving stability in the tire rubber composition having a low fuel consumption and wear resistance characteristics horn with silica, which is an additive of natural rubber or rubber composition with high rebound elasticity to improve the low fuel efficiency performance Rubber having a high styrene content and rubber having a low glass transition temperature (Tg) are added to a rubber composition of a material having a high vinyl content to increase the chemical resistance and always wear performance thereof. Properly adjusting the composition ratio has resulted in the development of a tire tung rubber composition that can improve driving stability such as braking performance while maintaining fuel economy and abrasion performance at an equivalent level.

Therefore, the present invention adds a rubber having a high styrene content and a rubber having a low glass transition temperature to a known tread rubber composition, and adjusts its composition ratio appropriately to maintain a conventional fuel economy and abrasion performance at equal or higher levels, such as braking force performance. An object of the present invention is to provide a tire tread rubber composition capable of improving stability.

In order to achieve the above object, the tire tread rubber composition having excellent wet traction is an emulsion styrene butadiene rubber (Emulsion-SBR) containing 20 to 60% of styrene in a known tire tread rubber composition. 45 parts by weight, styrene and vinyl 1: 1 mixed solution styrene butadiene rubber 30 to 45 parts by weight and neodymium butadiene rubber (Nd-BR) rubber containing 10 to 40 parts by weight as a raw material rubber It features.

In the present invention, the solution-polymerized styrene butadiene rubber in which the styrene butadiene rubber and the styrene and vinyl are mixed 1: 1 is used to obtain a tire tread rubber composition which improves the braking force, which is an object of the present invention when used in an amount of 30 to 45 parts by weight based on the weight of the raw rubber. Can be.

If the styrene content of emulsion styrene butadiene rubber is less than 20%, low fuel efficiency is improved, but the braking performance is lowered.If the styrene content is more than 60%, the braking performance is improved, but low fuel efficiency is lowered. In order to improve performance, the styrene content of the emulsion styrene butadiene rubber is preferably maintained at 20% to 60%.

In addition, the solution-polymerized styrene butadiene rubber was tested for styrene content and vinyl content under various conditions, and the best solution when using solution-polymerized styrene butadiene rubber containing 30% to 40% of styrene and 30% to 40% of vinyl as a raw material rubber Rubber specimens of physical properties were obtained.

Neodymium butadiene rubber (Nd-BR) is a butadiene rubber using neodymium (Nd) catalyst when synthesizing butadiene rubber. It has high cis- content and low glass transition temperature. Done. According to the present invention, when the neodymium butadiene rubber is used in an amount of 10 to 40 parts by weight based on the weight of the raw material rubber, a tire tread rubber composition for improving braking force, which is the object of the present invention, can be obtained.

The glass transition temperature of the emulsion styrene butadiene rubber was experimentally used in the emulsion styrene butadiene rubber, solution-polymerized styrene butadiene rubber and neodymium butadiene rubber as the raw material rubber of the present invention at various glass transition temperatures (Tg). Glass transition temperature of -30 ℃ to -40 ℃ and neodymium butadiene rubber of -100 ℃ to -110 ℃, solution-polymerized styrene butadiene rubber is the best characteristic when using as raw material rubber Rubber specimens were obtained.

On the other hand, neodymium butadiene rubber can obtain the best tread rubber specimen when using a cis content of 98% or more in addition to the glass transition temperature.

Hereinafter, the present invention will be described by the following comparative examples, examples and test examples. However, these do not limit the technical scope of the present invention.

Comparative Example

20 phr of natural rubber having the characteristics shown in Table 1, 20 phr of solution-polymerized styrene butadiene rubber (Solution SBR A) and 60 phr of solution-polymerized styrene butadiene rubber (Solution SBR B) as a known tire additive as a plasticizer ( Strucktol-40MS) 3 phr, Silica (Zeosil-175) 40 phr, Coupling agent (X-50S) 6.4 phr, Carbon black 30 phr, Active agent (ZnO # S) 3 phr, Antioxidant 2 phr, Wax 2 phr, active agent (Stearic acid) 2 phr, softener (oil) 3 phr, sulfur 2.0 phr, accelerator (N-cyclohexyl-2-benzothiazolsulfen amide (CZ) 1.9 phr, accelerator (Diphenyl guanidine, DPG) 0.3 phr After the addition, the mixture was vulcanized at 160 ° C. for 30 minutes to prepare a rubber specimen.

On the other hand, the rubber composition of the comparative example is shown in Table 2 below.

<Example 1>

40 phr of emulsion styrene butadiene rubber having the properties shown in Table 1, 40 phr of solution-polymerized styrene butadiene rubber (Solution SBR C), and 20 phr of neodymium butadiene rubber, using an oil that is a softener. Except not, rubber specimens were prepared using the same known tire additives and methods as in Comparative Examples.

<Example 2>

Except for use as raw material rubber consisting of 35 phr of emulsion styrene butadiene rubber (Emilsion SBR A), 35 phr of solution-polymerized styrene butadiene rubber (Solution SBR C) and 30 phr of neodymium butadiene rubber having the characteristics shown in Table 1 below. In the same manner as in Example 1, a rubber specimen was prepared.

Table 1. Microstructure of Raw Rubber in Rubber Compositions of Comparative Examples and Examples

division Styrene (%) vinyl(%) Cis (%) Tg (℃) Natural rubber - - - -62 Solution SBR A 25 73 - -14 Solution SBR B 15 57 - -43 Emulsion SBR A 40.5 - - -25 Solution SBR C 35 33 - -33 Nd-BR * - - 98 -109

Nd-BR: Trans-1,4 (%)> 1, Vinyl-1,2 (%) <1

Table 2. Rubber Compositions of Comparative Examples and Examples Specimen (Unit: phr)

Item Comparative example Example 1 Example 2 Natural rubber 20 - - Solution SBR A 20 - - Solution SBR B 60 - - Emulsion SBR A - 40 35 Solution SBR C - 40 35 tin coupled BR - 20 30 Plasticizer 3 3 3 Silica 40 40 40 Coupling agent 6.4 6.4 6.4 Carbon black 30 30 30 ZnO # S 3 3 3 Anti-aging 2 2 2 Wax 2 2 2 Stearic acid 2 2 2 Oil 3 - - Sulfur 2.0 2.0 2.0 Accelerator (CZ) 1.9 1.9 1.9 Accelerator (DPG) 0.3 0.3 0.3

<Test Example>

Rheometers, tensile properties, dynamic properties, Mooney viscosity, wear, rebound and exothermic properties of the rubber specimens of Comparative Examples and Examples were measured by known methods, and the results are summarized in Table 3 below. .

Table 3. Results of Measurement of Physical Properties of Comparative Examples and Examples

Item Comparative example Example 1 Example 2 Rheometer (160 ℃) T40 (minutes) 6.0 6.5 6.3 End of household (minutes) 11.4 12.3 12.0 Torque 43.7 35.6 37.2 Tensile Properties Hardness 94 82 85 300% modulus 67 66 67 Tensile strength (kgf / cm ² ) 135 115 120 % Elongation 203 216 220 Dynamic property Glass transition temperature (℃) 425 510 503 Tan δ (0 ℃) -23 -13 -16 Tan δ (70 ° C) 0.293 0.387 0.374 Mooney viscosity (100 ℃) 0.083 0.107 0.095 Wear (pico, mg) 24.7 27.5 26.1 Rebound (%) 32 24 29 Fever (℃) 24.7 30.0 32.2

As shown in Table 3, the rheometer and the tensile properties of the rubber specimens of the rubber composition of the present invention maintain the same level as the rubber specimens of the conventional rubber composition, while the hysteresis loss is determined by the high styrene content contained in the raw material rubber. By increasing the Tan δ and the friction coefficient at 0 ° C., a rubber composition having improved braking force can be obtained.

Claims (5)

In a known tire tread rubber composition, 30 to 45 parts by weight of emulsion styrene butadiene rubber (Emulsion-SBR), 30 to 45 parts by weight of solution-polymerized styrene butadiene rubber in which styrene and vinyl are mixed 1: 1, and neodymium butadiene rubber (Nd-BR) Excellent tread rubber composition with improved braking force, characterized by using 10-40 parts by weight of rubber as raw material rubber The excellent tread rubber composition according to claim 1, wherein the styrene butadiene rubber of the emulsion has a styrene content of 20 to 60% and a glass transition temperature (Tg) of -20 ° C to -30 ° C. The method of claim 1, wherein the styrene content of the solution-polymerized styrene butadiene rubber is 30% to 40%, the vinyl content is 30% to 40%, the glass transition temperature is -30 ℃ ~ -40 ℃ excellent braking force is improved Tread Rubber Composition The tread rubber composition of claim 1, wherein the neodymium butadiene rubber has a cis content of 98% or more and a glass transition temperature of -100 ° C to -110 ° C. A tire in which the rubber composition of any one of claims 1 to 4 is applied to a tread.