KR101114857B1 - Rubber composition for tire tread - Google Patents

Abstract

The present invention relates to a rubber tread rubber composition, wherein the rubber tread rubber composition comprises (1) 10 to 30 parts by weight of natural rubber, (2) styrene to 20 to 30% by weight, vinyl to 60 to 70% by weight. 30 to 40 parts by weight of solution-polymerized styrene-butadiene rubber prepared by a phosphorous continuous method, and (3) raw material rubber including 30 to 40 parts by weight of neodyne butadiene rubber; And 5 to 15 parts by weight of styrene-butadiene rubber gel containing 30 to 40 mg of KOH / g hydroxyl group, based on 100 parts by weight of the raw material rubber.

The rubber composition for tire treads according to the present invention has an advantage of improving braking performance on a snowy road surface, having excellent braking performance on a dry road surface and a wet road surface, and having low rotational resistance, and thus being applicable to four seasons.

Tire tread, rubber composition, four seasons, hydroxyl group

Description

Rubber composition for tire treads {RUBBER COMPOSITION FOR TIRE TREAD}

The present invention relates to a rubber tread rubber composition, and more particularly to a rubber tread composition applicable to four seasons.

Recently, as global warming accelerates, annual snowfall decreases rapidly and snow falls to form icy roads, but snow melts to form wet conditions such as slush or rain.

Since the properties of the rubber composition required for braking performance on dry or wet roads and snow and snow roads are mutually opposite, if one performance is chosen, the other performance is inevitably disadvantageous. In winter, many people replace the winter tires with excellent braking performance on the snowy road surface, but the braking performance becomes very disadvantageous when it is not snowing or when the snow melts and the wet road surface, which increases the demand for consumers. This is a trend, and in particular, as it is directly related to the stability of automobiles, it is a major concern of tire manufacturers, and research and development are actively being carried out to solve this problem.

In order to solve this problem, conventionally, styrene-butadiene rubber having a high styrene content in the tread tire rubber composition was used to increase the glass transition temperature of the rubber composition to improve braking performance on dry or wet roads. As the content is increased, the hardness and modulus of the rubber at a low temperature are increased, thereby reducing the braking performance on the ice snow road surface.

In addition, many methods using silica as a reinforcing agent are used. Silica has excellent reinforcement property compared to carbon black, which has excellent braking property on dry or wet roads, and has a low temperature dependence at low temperature. Since the increase rate is lower than that of carbon black, there is an advantage in terms of braking performance on ice and snow.

However, simply replacing the reinforcing agent from carbon black to silica in the winter tire tread rubber composition does not improve the braking performance on wet roads very effectively. The improvement of braking performance on wet roads of silica with winter tires has been very limited, and the proper matching of two contradictory performances to meet consumer demand remains a difficult technical challenge.

Accordingly, an object of the present invention is to provide a rubber composition for tire treads that can be applied for four seasons by improving braking performance on a snowy road surface and having excellent braking performance on dry and wet roads and low rolling resistance.

However, technical problems to be achieved by the present invention are not limited to the above-mentioned problems, and other technical problems will be clearly understood by the average technician from the following description.

In order to achieve the above object, the present invention is a solution prepared by the continuous method of (1) 10 to 30 parts by weight of natural rubber, (2) 20 to 30% by weight styrene content, 60 to 70% by weight vinyl content Raw material rubber containing 30 to 40 parts by weight of polymerized styrene-butadiene rubber, and (3) 30 to 40 parts by weight of neodymium butadiene rubber; And 5 to 15 parts by weight of styrene-butadiene rubber gel containing hydroxyl groups as 30 to 40 mg KOH / g gel, based on 100 parts by weight of the raw material rubber.

The rubber composition for tire treads according to the present invention has an advantage of improving braking performance on a snowy road surface, having excellent braking performance on a dry road surface and a wet road surface, and having low rotational resistance, and thus being applicable to four seasons.

The present invention 1) 10 to 30 parts by weight of natural rubber, 2) 20 to 30% by weight of styrene, 60 to 70% by weight of vinyl in butadiene solution polymerized styrene-butadiene rubber prepared by the continuous method 40 parts by weight, 3) 5 to 15 parts by weight of a styrene-butadiene rubber gel containing a large amount of hydroxyl group (-OH) in a raw material rubber containing 30 to 40 parts by weight of neodymium butadiene rubber. The addition provides a rubber composition for tire treads that can improve the braking performance on dry or wet road surfaces without deteriorating braking performance on winter snow treads.

Hereinafter, the present invention will be described in more detail.

The present invention raw material rubber; A rubber composition for tire treads comprising a styrene-butadiene rubber gel comprising hydroxyl groups in a 30 to 40 mg KOH / g gel.

The raw material rubber is (1) natural rubber, (2) a solution-polymerized styrene-butadiene rubber prepared by a continuous process having a styrene content of 20 to 30% by weight, the vinyl content of 60 to 70% by weight of butadiene, (3) Neodyne butadiene rubber.

The natural rubber is a rubber obtained from nature, the chemical name is polyisoprene, and can be further improved by using a solution-polymerized styrene-butadiene rubber produced by the continuous method to further improve braking performance on wet road surfaces.

The natural rubber is included in 10 to 30 parts by weight based on 100 parts by weight of the raw rubber. If the content of the natural rubber is less than 10 parts by weight, there is a problem that the durability of the tread rubber is lowered, and if it exceeds 30 parts by weight, there is a problem that the braking performance on the wet road surface is lowered.

The styrene-butadiene rubbers according to the invention are produced in a continuous process.

In general, solution-polymerized styrene-butadiene rubbers are prepared by continuous and batchwise processes. Styrene-butadiene rubber produced by the continuous method is disadvantageous in terms of rotational resistance in comparison with styrene-butadiene rubber produced by the batch method due to a large amount of low molecular materials, but has excellent processability, and has high hysteresis loss, so that dry or wet roads Excellent braking performance at.

The styrene-butadiene rubber has a styrene content of 20 to 30% by weight, and a vinyl content in butadiene of 60 to 70% by weight. When the styrene content and the butadiene content are in the above range, there is an advantage that the braking performance on the wet road surface is optimally exhibited.

The styrene-butadiene rubber is included in 30 to 40 parts by weight based on 100 parts by weight of the raw rubber. When the content of the styrene-butadiene rubber is less than 30 parts by weight, there is a problem that the braking performance on the wet road surface is lowered, and when it exceeds 40 parts by weight, on the contrary, the braking performance on the ice snow road surface is deteriorated.

The neodymium butadiene rubber has a narrower molecular weight distribution than cobalt butadiene rubber (Co-BR) or nickel butadiene rubber (Ni-BR), and has a low molecular hysteresis because of low linear hysteresis. There is an excellent advantage in performance.

The neodymium butadiene rubber is included in an amount of 30 to 40 parts by weight based on 100 parts by weight of the raw material rubber. When the content of neodymium butadiene rubber is less than 30 parts by weight, there is a problem in that braking performance and abrasion resistance on a snowy snow road are reduced, and when it exceeds 40 parts by weight, braking performance on a wet road surface is deteriorated.

The styrene-butadiene rubber gel contains 30-40 mg KOH / g gel of hydroxyl groups. When the content of the hydroxyl group is less than 30 mg KOH / g gel, there is a problem that the braking performance on the wet road surface is lowered, and when the hydroxyl content exceeds 40 mg KOH / g gel, there is a problem that the braking performance on the ice snow road surface is reduced .

In addition, the styrene-butadiene rubber gel has a glass transition temperature of -20 to -10 ° C and a gel diameter of 30 to 60mm.

When the glass transition temperature of the styrene-butadiene rubber gel is within the above range, the braking performance of the styrene-butadiene rubber gel can be obtained without sacrificing the braking performance on the ice road surface, and the gel diameter is within the above range. The above effect can be obtained.

The styrene-butadiene rubber gel is included in 5 to 15 parts by weight based on 100 parts by weight of the raw rubber. When the content of the styrene-butadiene rubber gel is less than 5 parts by weight, the braking performance improvement effect on the wet road surface is insignificant, and when it exceeds 15 parts by weight, the workability is deteriorated, the braking performance on the ice snow road is greatly reduced, and the steering stability is disadvantageous. Termination results in adverse effects.

The styrene-butadiene rubber gel according to the present invention has a large amount of hydroxyl groups on its surface, thereby chemically bonding with rubber through a coupling agent, and having a low temperature region (0 ° C. to 20 ° C.) by a highly crosslinked core portion. The hysteresis increases at) and the braking property is excellent on dry or wet road surface.

In the case of a conventional raw material rubber, the hardness and modulus increase as the temperature decreases, and the styrene-butadiene rubber gel has a very small change, and thus has a relatively low hardness and modulus value even at a low temperature below 0 ° C. It also has a beneficial effect on braking performance.

In addition, the chemical bonding with the rubber through the coupling agent has a low hysteresis in the high temperature range (50 ℃ ~ 80 ℃), the effect of lowering the rolling resistance also occurs.

The present invention further includes silica as a reinforcing filler, and may be used alone, or a silane coupling agent may be used to improve dispersibility of the silica.

The silica has a nitrogen adsorption amount of 160 to 180 m 2 / g, CTAB value 140 to 160 m 2 / g. Only when the nitrogen adsorption amount and CTAB value are within the above range, the effect according to the present invention can be obtained.

The silica is included in 60 to 90 parts by weight based on 100 parts by weight of the raw rubber. If the silica content is less than 60 parts by weight, the reinforcement is deteriorated, and the braking performance and the handling performance of the wet road surface are deteriorated. If the content is more than 90 parts by weight, the braking performance and the abrasion resistance on the ice surface are deteriorated. there is a problem.

Meanwhile, the rubber composition according to the present invention may further include a silane coupling agent, a softener, a vulcanizing agent, a vulcanization accelerator, and an anti-aging agent.

The silane coupling agent is used to improve the dispersibility of silica, and bis- (trialkoxy silyl propyl) polysulfide (TESPD) and bis-3-triethoxy silylpropyl tetrasulfide (TESPT) among alkoxy polysulfide silane compounds. TESPT is sold under the trade name Si75 at Degussa, and TESPD is a commercially available blend of 50% carbon black and 50% X50S under the trade name Si69 at Degussa.

The silane coupling agent is included in 10 to 20 parts by weight based on 100 parts by weight of the raw material rubber. When the content of the silane coupling agent is in the above range, there is an advantage that the coupling efficiency is maximized.

In addition, the processing oil used as the softener of the present invention has a total content of PolyHyclic Aromatic Hydocarbo (PAH) component of 3% by weight or less, a kinematic viscosity of 95 ° C (210 ° F SUS), an aromatic component of 15-25% by weight of the softener, The naphthenic component is 27 to 37% by weight and the paraffinic component is 38 to 58% by weight. If the processing oil satisfies all of the above conditions, there is an advantage that the braking performance of the wet road surface and the snow surface can be balanced.

The processing oil is preferably used in 20 to 30 parts by weight based on 100 parts by weight of the raw material rubber. When the content of the processing oil is within the above range, the braking performance on the ice and wet road surface is excellent and the processability is also advantageous.

It is preferable to use a sulfur vulcanizing agent. Examples of the sulfur vulcanizing agent include vulcanizing agents for producing elemental sulfur or sulfur, such as amine disulfide and high molecular sulfur, and preferably elemental sulfur.

The vulcanizing agent is included in 1.5 to 2.5 parts by weight based on 100 parts by weight of the raw material rubber. When the content of the vulcanizing agent is within the above range, by forming an appropriate crosslinking density, there is an advantage that an optimum balance of braking performance, abrasion resistance, and rolling resistance can be achieved.

Further, vulcanization accelerators include amine, disulfide, guanidine, thio urea, thiazole, thiuram, sulfene amide, and the like.

The vulcanization accelerator is included in 0.8 to 2.0 parts by weight based on 100 parts by weight of the raw material rubber. When the content of the vulcanization accelerator is in the above range there is an advantage that can form an appropriate crosslink density.

The anti-aging agent is N- (1,3-Dimethybytyl) -N-phenyl-p-phenlenediamine (6PPD), N-phenyl-n-isopropyl-p-phenylenediamine (3PPD), Poly (2.2.4-trimethyl-1.2 -dihydroquinoline (RD) etc. are mentioned.

The anti-aging agent is included in 1 to 5 parts by weight based on 100 parts by weight of the raw material rubber. When the content of the anti-aging agent is in the above range there is an advantage that the roadbed effect is maximized.

On the other hand, the present invention, of course, in addition to the above-mentioned composition, various additives such as activators, processing oils, vulcanizing agents and vulcanization accelerators used in conventional tire tread compositions can be selected and used as necessary.

Hereinafter, preferred examples and comparative examples of the present invention are described. However, the following examples are only preferred embodiments of the present invention and the present invention is not limited to the following examples.

[Examples 1-3 and Comparative Examples 1-5]

To prepare a tire rubber composition according to Examples 1 to 3 and Comparative Examples 1 to 5 using the composition shown in Table 1. The tire rubber composition was produced by a conventional tire manufacturing method.

Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Example 1 Example 2 Example 3 Natural rubber 20 20 20 20 20 20 20 20 S-SBR (1) 55 0 0 0 0 0 0 0 S-SBR (2) 0 55 55 55 55 55 55 55 BR (1) 55 55 0 0 0 0 0 0 BR (2) 0 0 55 55 55 55 55 55 Styrene Butadiene
Gel rubber 0 0 0 2 20 5 10 15 Silica 86 86 86 86 86 86 86 86 Coupling agent
Processing oil 14
25.6 14
25.6 14
25.6 14
25.6 14
25.6 14
25.6 14
25.6 14
25.6 Zinc oxide 3 3 3 3 3 3 3 3 Stearic acid One One One One One One One One Anti-aging 2.4 2.4 2.4 2.4 2.4 2.4 2.4 2.4 Vulcanizer 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 accelerant
Accelerator (DPG) 1.5
2 1.5
2 1.5
2 1.5
2 1.5
2 1.5
2 1.5
2 1.5
2

(Unit: parts by weight)

(week)

1) Natural rubber: Rubber obtained from nature, chemical name is polyisoprene

2) S-SBR (1): solution-polymerized styrene-butadiene rubber (SBR) prepared by a batch method of styrene content of 24% by weight and vinyl content of butadiene in 66% by weight, 37.5 parts by weight of TDAE Oil.

3) S-SBR (2): solution-polymerized styrene-butadiene rubber (SBR) prepared by the continuous method of styrene content of 24% by weight and vinyl content of 66% by weight of butadiene, 37.5 parts by weight of TDAE Oil

3) BR (1): Nickel butadiene rubber made by Kumho Petrochemical Co., Ltd.

4) BR (2): Neodye butadiene rubber made by Lanxess, trade name CB29MES, MES Oil 37.5 parts by weight extended

5) Styrene butadiene gel rubber: Styrene-butadiene gel rubber containing hydroxyl group of Lanxess, trade name Nanoprene BM15OH

6) Silica: precipitated silica with nitrogen adsorption value of 175㎡ / g and CTAB value of 154㎡ / g

7) Processed oil: PAH (PolyCyclic Aromatic Hydocarbo) content is below 3 wt%, kinematic viscosity is 95 ℃ (210 ℉ SUS), 25 wt% aromatic component, 32.5 wt% naphthenic component and paraffinic An oil of 47.5% by weight, brand name Vivatec500

8) Anti-aging agent: UNIBOND (trade name), 6PPD (brand name)

9) Vulcanizer: Miwon Corporation (trade name), MIDAS101 (brand name)

10) Promoter: Flexsys (trade name), CZ (brand name)

11) Promoter (DPG): Flexsys (trade name), DPG (brand name)

The physical properties were tested for the prepared specimens, and the results are shown in Table 2 below.

Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Example 1 Example 2 Example 3 Mooney viscosity 70 66 69 70 82 72 75 78 Hardness (ShoreA) 66 66 66 66 63 66 65 64 300% Modulus (Mpa) 8.0 7.9 8.0 7.9 9.4 8.4 8.6 9.0 -40 ℃ G '
(dyne / ㎠) 8.9E + 08 9.3E + 08 9.0E + 08 1.24E + 09 9.1E + 08 9.5E + 08 9.7E + 08 1.04E + 09 0 ℃ tanδ 0.222 0.230 0.229 0.230 0.352 0.244 0.254 0.292 60 ℃ tanδ 0.152 0.155 0.147 0.135 0.109 0.128 0.124 0.113

Corporation

Pattern viscosity (ML1 + 4 (125 ° C.)) was measured according to ASTM standard D1646.

Hardness was measured according to DIN 53505

300% modulus, measured according to ISO 37 standard.

-Viscoelasticity was measured by GDS, G ", tan δ from -60 ℃ to 60 ℃ under 10Hz frequency at 0.5% strain using an RDS meter.

In Table 2, ML1 + 4 is a value representing the viscosity of the unvulcanized rubber, and the lower the value, the better the workability of the unvulcanized rubber. Hardness indicates steering stability. The higher the value, the better the steering stability. -40 ℃ G 'shows the braking characteristics on the ice road surface. The lower the value, the better the braking performance. The 0 ℃ tanδ shows the braking performance on the dry or wet road surface. The higher the value, the better the braking performance. . In addition, 60 ° C tan δ indicates rotational resistance characteristics, and a lower value indicates better performance.

Relative to the braking distance and rolling resistance on dry road, wet road, and snow road surface by manufacturing tires of the 205 / 55R16 standard made of rubber of the comparative examples and examples and including the tread rubber as semi-finished products. The ratios are shown in Table 3 below.

Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Example 1 Example 2 Example 3 Dry road braking distance 100 100 101 100 93 98 96 95 Wet road
Braking distance 100 98 98 98 88 95 92 90 Snow surface
Braking distance 100 102 100 100 108 101 102 103 Rolling resistance 100 102 98 97 90 95 93 91

As described above, the solution-polymerized styrene-butadiene prepared by the continuous type compared to the case of using the solution-polymerized styrene-butadiene rubber prepared by batch (Comparative Example 1) or the case of using nickel butadiene rubber (Comparative Example 2). When rubber and neodyne butadiene rubber are used (Comparative Example 3), braking performance on wet road surface is improved without deterioration of braking performance on ice and snow road, and 5 to 15 styrene-butadiene rubber gel containing a large amount of OH group is added. It can be seen that when added by weight, the braking performance of the dry road and the wet road surface is greatly reduced without significantly deteriorating the braking performance of the snow road.

All simple modifications or changes of the present invention can be easily carried out by those skilled in the art, and all such modifications or changes can be seen to be included in the scope of the present invention.

Claims (2)

(1) 10 to 30 parts by weight of natural rubber, (2) 20 to 30% by weight of styrene and 60 to 70% by weight of vinyl in butadiene, a solution-polymerized styrene-butadiene rubber prepared by a continuous process. Parts by weight, (3) raw rubber including 30 to 40 parts by weight of neodymium butadiene rubber; And A rubber composition for a tire tread, comprising 5 to 15 parts by weight of styrene-butadiene rubber gel containing 30 to 40 mg KOH / g gel of hydroxyl groups based on 100 parts by weight of the raw material rubber. delete