KR20020037591A - Rubber composition for tire - Google Patents

Abstract

PURPOSE: A rubber composition for a tire is provided, to improve the abrasion resistance and the braking efficiency without deterioration of the control stability and the gasoline mileage by employing three kinds of rubbers with the controlled molecular structure characteristics and molecular weight characteristic. CONSTITUTION: The rubber composition comprises 100 parts by weight of a blending rubber which comprises 70-90 wt% of two kinds of styrene-butadiene rubbers with different properties prepared by emulsion polymerization, and 10-30 wt% of butadiene rubber; 65-96 parts by weight of carbon black; and common additives. The butadiene rubber has a glass transition temperature of -110 to -100 deg.C; is prepared by solution polymerization; and contains 1,4-cis butadiene by 96% or more. Preferably the two kinds of styrene-butadiene rubbers comprises 20-60 parts by weight of styrene-butadiene rubber which has a glass transition temperature of -40 to -20 deg.C, a Mooney stress relaxation time slope at 100 deg.C of -0.35 to -0.40 and a Mooney viscosity at 100 deg.C of 55-65, and contains 38-42 parts by weight of styrene and 25-29 parts by weight of an aromatic oil; and 30-70 parts by weight of styrene-butadiene rubber which has a glass transition temperature of -60 to -40 deg.C, a Mooney stress relaxation time slope at 100 deg.C of -0.30 to -0.35 and a Mooney viscosity at 100 deg.C of 55-65, and contains 20-25 parts by weight of styrene and 25-29 parts by weight of an aromatic oil.

Description

Rubber composition for tires with improved wear and braking resistance

The present invention relates to a rubber composition for tires having improved abrasion resistance and braking resistance, and more particularly, by newly designing molecular structure and molecular weight characteristics of styrene-butadiene diene rubber produced by an emulsion polymerization method useful in the tire industry. A special carbon black is used for rubber substrates made of two new concepts of styrene-butadiene rubber and high-cis butadiene rubber with 1,4 cis-butadiene content in the microstructure composition to improve wear resistance and braking resistance. It relates to a rubber composition that can be made.

Most of the development of tires can be concentrated on the structural aspects and the technical aspects of the materials used in the tires. In particular, in the tire materials, most research is focused on the development of tires considering energy saving and the environment.

In recent years, tire development trends in terms of materials have been developed for low fuel cost tires, high wear resistance and high braking tires, and tires that combine such characteristics with chip cut performance. In particular, the recent tire rubber compounding technology is concentrated on the technology of combining these characteristics, and for this purpose, research and development is being attempted to apply various new materials recently developed.

For example, Japanese Patent Laid-Open Nos. 55-12133 and 56-127650 describe rubber compounding compositions to which high vinyl butadiene (hereinafter referred to as V-BR) is described, and Japanese Patent Laid-Open Nos. 57-55204 and Japanese Patent Application Laid-Open No. 57-73030 discloses a rubber compounding composition using high vinyl styrene butadiene (hereinafter referred to as V-SBR), but these cases exhibit high wet braking and low heat generation characteristics but are inferior in abrasion resistance properties. Indicates.

In addition, Japanese Patent Laid-Open No. 61-131741 and Japanese Patent Laid-Open No. 61-42552 also use V-SBR, but it is known that they do not solve inferior abrasion resistance performance.

Therefore, when it is difficult to expect the improvement of physical properties through the polymer was to solve the problem by applying a new carbon black. For example, in Japanese Patent Application Laid-Open No. 59-2451, the minimum unit in which carbon black exhibits a reinforcing effect in the formulation is agglomerated, including conventional methods such as using carbon black having a small particle size or reducing the amount of carbon black used. Applying the results of the research, the gate size (aggregate size), the invention mainly invented a compound composition that maintains a high level of resistance, such as high wear resistance and high braking resistance, low fuel efficiency and field mixing processability, but also abrasion resistance significantly increased I couldn't.

Therefore, the inventors of the present invention while trying to solve such a conventional problem, as a result of mixing and using a mixture of three different types of rubber, the molecular structure characteristics and molecular weight characteristics appropriately adjusted in a certain ratio, and added a useful reinforcing agent, The present invention has been found to be able to solve workability problems while improving wear resistance and braking performance without loss of adjustment stability or low fuel consumption performance.

Accordingly, it is an object of the present invention to provide a rubber composition for a tire which is capable of improving workability and improving wear resistance and braking resistance without loss of adjustment stability and low fuel efficiency.

The rubber composition for tires of the present invention for achieving the above object is 70 to 90 parts by weight (pure rubber ratio) of two kinds of styrene-butadiene rubbers having different characteristics prepared by the emulsion polymerization method and the solution polymerization method 100 parts by weight of a blended rubber comprising a diene rubber having a glass transition temperature of −110 to 100 ° C. and a blend of 10 to 30 parts by weight of butadiene rubber having a 1,4-cis butadiene content of 96% or more in a microstructure composition; 65 to 95 parts by weight of carbon black; And it is characterized by consisting of the usual additives.

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

The rubber composition of the present invention is 70 to 90 parts by weight (pure rubber ratio) of two kinds of diene rubbers prepared by emulsion polymerization and 10 to 30 parts by weight (pure rubber ratio) of diene rubbers prepared by the solution polymerization method. As a useful reinforcing agent with respect to 100 parts by weight of the blended rubber made, 65 to 95 parts by weight of carbon black is used and is made of conventional additives.

Here, looking specifically at two styrene-butadiene rubbers having different characteristics prepared by the emulsion polymerization method,

One of them has a glass transition temperature of -40 to -20 ° C, styrene content of 38 to 42 parts by weight, aromatic oil content of 25 to 29 parts by weight, 100 ° C pattern viscosity of 55 to 65, and stress relaxation. Styrene butadiene rubber (hereinafter referred to as E-SBR-I) having a time stress (Mooney Stress Relaxation Time Slope, Log T / log at at 100 ° C.),

The other one has a glass transition temperature of -60 to -40 ° C, a styrene content of 20 to 25 parts by weight, an aromatic oil content of 25 to 29 parts by weight, a 100 ° C pattern viscosity of 55 to 65, and a stress relaxation The styrene butadiene rubber (hereinafter referred to as E-SBR-II) having a time stress (Mooney Stress Relaxation Time Slope, Log T / log at 100 ° C.) is -0.30 to-0.35.

The specific composition is 20 to 60 parts by weight of E-SBR-I and 30 to 70 parts by weight of E-SBR-II. The composition ratio here depends on the net rubber ratio.

When the pattern viscosity of the styrene-butadiene rubber is less than 50 or the pattern viscosity is 70 or more, the effect of increasing the wear resistance and the braking performance according to the addition of the styrene-butadiene rubber is not large. In particular, one of the two styrene butadiene rubbers does not use a rubber having a pattern viscosity of 70 or more, or a rubber having a suitable stress relaxation time slope (Log T / log at 100 ° C). In the case of poor compatibility with butadiene rubber and when the amount of carbon black is increased, there are many problems in the field processability.

In addition, when the aromatic oil content inherited in each styrene-butadiene rubber is less than 24 parts by weight, carbon black incorporation and processing are poor.

When the added amount of E-SBR-I is less than 20 parts by weight, the wet road surface braking property and the dry road surface braking property are not improved, and when the amount of E-SBR-I is more than 60 parts by weight, the increase in wear resistance is not obvious.

If the amount of E-SBR-II added is less than 30 parts by weight, the increase in abrasion resistance is not apparent. If the amount of E-SBR-II is more than 70 parts by weight, wet road surface braking property and dry road surface braking property are inferior.

Two kinds of styrene-butadiene rubbers having such different characteristics are used as 70 to 90 parts by weight of the total blending rubber, and the rest is added butadiene rubber, but the butadiene rubber has a glass transition temperature of -110 as described above. It is --100 degreeC, and it is preferable that 1, 4- cis butadiene content is 96% or more in a microstructure composition.

As described above, since the pattern viscosity of the styrene-butadiene rubber is 55 to 65 and the molecular weight is very high, it is not preferable to use the butadiene pure rubber weight ratio in excess of 30 parts by weight.

Meanwhile, the carbon black added as a reinforcing agent in the present invention is not particularly limited, but CTAB is 132 m 2 / g, ISA is 140 mg / g, DBP is 130ml / 100g, C-DBP is 110ml / 100g or more, TINT Is preferably 125 or more and N 2 SA is 145 m 2 / g.

The carbon black is added to 65 to 95 parts by weight based on 100 parts by weight of the blended rubber. If the amount is too small, that is, 60 parts by weight or less, a low heat generation composition can be obtained, but the reinforcing effect is poor. It causes a problem in performance, if more than 100 parts by weight due to poor dispersion of carbon black, the workability is poor and the wear resistance is adversely affected.

In addition, in the present invention, zinc additives, stearic acid, sulfur, accelerators and the like can be used as usual additives.

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

To the styrene-butadiene rubber and butadiene rubber having the characteristics as shown in Table 2, carbon black and the usual additives were formulated in the component ratio shown in Table 1 to prepare a rubber composition. This was vulcanized to prepare a rubber specimen. This formulation method used the method used in ASTM 3185-99 for convenience. The unit of the component ratio of a composition in Table 1 is a weight part.

Comparative Examples 1 to 8

To the styrene-butadiene rubber and butadiene rubber having the characteristics as shown in Table 2, carbon black and the usual additives were blended in the component ratio shown in Table 1 to prepare a rubber composition. This was vulcanized to prepare a rubber specimen.

Example Comparative Example One 2 3 One 2 3 4 5 6 7 8 Butadiene rubber 20 30 10 20 20 20 10 40 30 30 5 SBR-A 35 30 SBR-B 55 SBR-C 30 45 70 55 40 40 SBR-D 35 45 SBR-E 45 SBR-F 35 SBR-G 50 25 20 45 25 30 30 55 SBR-H 25 Carbon black 68 77 93 80 75 83 83 80 70 105 55 Extension oil in rubber 30 26.3 33.8 30 30 30 33.8 22.5 26.3 26.3 35.6 Extension oil during blending 7.5 11.2 3.7 7.5 7.5 7.5 3.7 15.0 11.2 11.2 1.9 ZnO 3 3 3 3 3 3 3 . 3 3 3 Stearic acid One One One One One One One One One One One brimstone 2.2 2.2 2.2 2.2 2.2 2.2 2.2 2.2 2.2 2.2 2.2 accelerant 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 SBR Co., Ltd .: Styrene-butadiene rubber carbon black: CTAB is 132㎡ / g, ISA is 140mg / g, DBP is 130ml / 100g, C-DBP is 110ml / 100g or more, TINT is 125 or more, N2SA is 145㎡ / g carbon black

Synthetic rubber type Viscosity Viscosity ML _{1 + 4} @ 100 Glass transition temperature (-℃) Oil content (%) Styrene Content (%) Stress Relaxation Slope (-logT / logt) SBR-A 49 52 27.3 23.5 0.36 SBR-B 68 45 27.3 27.3 0.28 SBR-C 61 49 27.3 23.5 0.33 SBR-D 62 62 27.3 21.5 0.28 SBR-E 50 37 27.3 39.0 0.43 SBR-F 69 17 27.3 45.0 0.33 SBR-G 63 29 27.3 10.0 0.37 SBR-H 60 22 27.3 43.0 0.34 Butadiene rubber 45 45 1,4-cis butadiene content of more than 96%

Experimental Example

The physical properties of the rubber compositions prepared in Examples 1 to 3 and Comparative Examples 1 to 8 were measured, and the results are shown in Table 3 below.

Physical property measurement method is as follows.

1) Rheometer t ₅ Measuring temperature: 125 ℃

2) Rheometer t ₉₀ Temperature: 150 ℃

3) Tensile test condition: Equipment used (Instron), Cross Head Speed: 500mm / min.

Vulcanization Condition: 150 ℃ × 30 min.

4) Surface roughness: 1 to 5 (the larger the number, the smoother surface)

5) Heat generation characteristics: Use BF Goodrich Flexometer (the bigger the index, the better the heat generation performance)

Example Comparative Example One 2 3 One 2 3 4 5 6 7 8 Scorch Safety t ₅ (min) 18.1 18.5 19.2 17.5 19.1 17.4 18.5 18.1 15.8 18.2 15.6 Rheometer t ₉₀ (min) 12.5 12.1 12.3 12.3 13.1 11.5 13.3 13.1 10.8 13.1 11.4 Intrinsic viscosity @ 125 65 72 78 68 61 94 89 81 92 98 54 Hardness (Shore A) 66 67 66 70 58 74 68 66 78 83 62 M300 (㎏ / ㎠) 125 135 143 111 104 116 118 124 110 84 98 Cutting strength (㎏ / ㎠) 158 165 167 124 121 131 129 141 125 84 98 % Elongation 510 480 460 470 500 440 430 440 460 360 550 Toughness 135 131 133 100 91 98 138 126 121 74 101 Rambon Wear (Indexed) 128 131 132 100 91 98 94 91 92 84 85 Surface roughness 5 4 4 3 2 2 One 2 4 One 5 Wet Surface Braking (Index) 111 109 114 100 94 100 104 97 95 91 96 Dry Surface Braking (Index) 108 103 104 100 91 101 100 102 91 94 98 0 ℃ tanδ (exponentialization) 108 116 112 100 96 98 100 96 91 109 91 60 ° C tanδ (indexed) 101 104 100 100 91 103 104 99 94 115 93

From the results of Table 3, it can be seen that the results of using the rubber composition according to the present invention, the adjustment stability and low fuel consumption performance is equivalent to or more, but also wear resistance and braking performance.

As described above in detail, according to the present invention, two types of styrene-butadiene rubbers and butadiene rubbers having a patterned viscosity, a stress relaxation time slope and a microstructural component in which a molecular structure characteristic and a molecular weight characteristic are optimized, and an aromatic oil are inherited When the mixture is used as a rubber base, a rubber composition having improved abrasion resistance and braking performance can be obtained without loss of existing physical properties, that is, adjusting stability or low fuel consumption performance.

Claims (2)

70 to 90 parts by weight of two kinds of styrene-butadiene rubbers (pure rubber ratio) having different properties prepared by the emulsion polymerization method and the solution polymerization method, the glass transition temperature is -110 ~ -100 ℃, microstructure composition A rubber composition for a tire, comprising 100 parts by weight of a blending rubber consisting of 10 to 30 parts by weight of butadiene rubber having a 1,4-cis butadiene content of 96% or more, and 65 to 95 parts by weight of carbon black and a conventional additive. According to claim 1, The two styrene-butadiene rubbers having different characteristics prepared by the emulsion polymerization method has a glass transition temperature of -40 ~ -20 ℃, styrene content of 38 to 42 parts by weight, Styrene butadiene having an aromatic oil content of 25 to 29 parts by weight and a pattern viscosity of 55 to 65 at 100 ° C and a stress relaxation time slope of (0.3 ° to 0.40). 20 to 60 parts by weight of rubber; The glass transition temperature is -60 to -40 ℃, the styrene content of the microstructure composition 20 to 25 parts by weight, aromatic oil content 25 to 29 parts by weight, 100 ℃ pattern viscosity is 55 to 65, the stress relaxation time slope ( Mooney Stress Relaxation Time Slope, Log T / log at 100 ℃) rubber composition for a tire, characterized in that consisting of 30 to 70 parts by weight of styrene butadiene rubber of -0.30-0.35.