KR20040050039A - Rubber composition for tire tread - Google Patents

Abstract

PURPOSE: Provided is a tire tread rubber composition using a new reactive resin, which can improve a wet grip performance without lowering a rotation resistance of a tire. CONSTITUTION: The tire tread rubber composition comprising a general diene-based silica blended rubber contains 1-15pts.wt.(based on the raw rubber of 100pts.wt.) of the reactive resin containing alpha-methyl styrene, styrene, and indene, wherein the indene part is substituted by maleic acid as a reactive group. The reactive resin has a molecular weight of 1,000-10,000 and the substitution ratio of the maleic acid is 5-20%.

Description

Rubber composition for tire tread

The present invention relates to a tire tread rubber composition, and more particularly, to a tire tread rubber composition having improved wet grip performance without deterioration in rolling resistance by using a reactive resin in which maleic acid is added to α-methyl styrene, styrene and indene. will be.

In order to improve the wet grip performance of the tire, it is necessary to increase the hysteresis loss (tanδ) of the tread portion, which can be expressed at a frequency corresponding to the cyclic deformation of the rubber of the tire tread portion when the tire moves on the uneven surface of the road. .

On the other hand, reducing the rolling resistance of the tire, that is, improving fuel economy, requires lowering the hysteresis loss of the tread portion at a frequency corresponding to the rotational speed of the tire.

In general, the wet grip corresponds to 0 ° C. tanδ at a frequency of 10 Hz, and the rolling resistance of the tire corresponds to tan δ around 60 ° C. at 10 Hz.

In order to improve the wet grip of a conventional tire, styrene-butadiene rubber containing styrene as a polymer is used, and carbon black having a small particle size is highly filled or a petroleum softener is used. However, the change of polymer and the high filling of carbon black with small particle diameter are closely related to abrasion resistance and adjustment stability of a tire, and thus its use is very limited to increase wet grip without any other performance change.

In addition, petroleum-based softeners and low molecular weight asphalt resins may be used to increase wet grip. However, such formulations increased 0 ° C tanδ at a frequency of 10 Hz, while tanδ at 60 ° C also increased, resulting in tire rolling resistance. Performance deteriorates dramatically.

Recently, high-softening point (50-220 ℃) resins (DCPD (dicyclopentadiene) and limonene resin) are used instead of petroleum softeners or low molecular weight asphalt resins, which are poor in rolling resistance, to improve wet grip performance. Have been reported, but these techniques have also slightly reduced losses in rolling resistance, but have not seen a fundamentally significant effect (US Pat. No. 6,245,873 B1).

Accordingly, an object of the present invention is to provide a tread rubber composition that can improve wet grip without deterioration of the rolling resistance performance of a tire by using a new kind of reactive resin.

The tire tread rubber composition of the present invention for achieving the above object is a diene-based silica compounding rubber composition, which includes α-methyl styrene, styrene and indene as a reactive resin, and a maleic acid resin with maleic acid whose indene site is a reactive group. It is characterized by including the.

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

The rubber composition for tire tread of the present invention comprises α-methyl styrene, styrene and indene as a reactive resin in a tire tread rubber composition made of a conventional diene silica compounded rubber, and includes a resin maleinic acid with maleic acid whose indene site is a reactive group. do. Specifically, the reactive resin preferably has a molecular weight of 1,000 to 10.000 and a maleic acid substitution rate of about 5 to 20%.

Reactive resin having such a structure is wet grip without deterioration of rotational resistance by reducing the fluidity of the resin in which the carboxyl groups and silanol groups on the surface of silica induce chemical or hydrogen bonding with each other to improve rotational resistance. It can improve performance.

The content of such reactive resin is 1 to 15 parts by weight, preferably 3 to 10 parts by weight, based on 100 parts by weight of the raw material rubber. If the content is less than 1 part by weight based on 100 parts by weight of rubber, the physical properties are improved, but the effect is insignificant, if more than 15 parts by weight there is a problem that the rotational resistance performance is reduced.

In addition, the rubber composition of the present invention contains a solution-polymerized styrene-butadiene rubber, butadiene rubber as a raw material rubber, as in the conventional tire tread rubber composition, silica as a reinforcing agent, aromatic oil as a softener, coupling agent, zinc oxide, stearic acid, aging Of course, it includes an inhibitor, a vulcanizing agent and a vulcanization accelerator.

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

Examples 1-4 and Comparative Examples 1-3

Next, a rubber composition for tire treads was prepared according to the composition and blending ratio as shown in Table 1 below. The rubber composition was prepared as a test specimen, and 0 ° C. tanδ (wet grip performance), 60 ° C. tanδ (low fuel efficiency) and tensile properties were measured. The results are shown in Table 1 below.

Here, modulus, tensile strength and elongation were measured using a tensile tester (ASTM D-638), tanδ is measured according to the method using DMTS (10Hz, 0.5% strain).

Comparative example Example One 2 3 One 2 3 4 Furtherance s-SBR 75 75 75 75 75 75 75 BR 25 25 25 25 25 25 25 Silica 80 80 80 80 80 80 80 Aromatic oils 35 35 35 35 35 35 35 TESPT 6.4 6.4 6.4 6.4 6.4 6.4 6.4 Zinc oxide 2.5 2.5 2.5 2.5 2.5 2.5 2.5 Stearic acid 2 2 2 2 2 2 2 6C 1.5 1.5 1.5 1.5 1.5 1.5 1.5 Resin 1 - 3 - - - - - Resin 2 - - 20 One 3 5 10 Diphenylguanidine 1.5 1.5 1.5 1.5 1.5 1.5 1.5 sulfur 1.1 1.1 1.1 1.1 1.1 1.1 1.1 CB 2 2 2 2 2 2 2 Properties 100% Modulus (Index) 100 94 78 96 94 91 91 300% modulus (index) 100 88 96 97 98 109 104 Tensile Strength (Index) 100 94 138 108 113 118 125 Elongation (index) 100 103 134 104 109 115 121 0 ℃ tanδ 0.724 0.788 0.930 0.762 0.792 0.835 0.891 60 ℃ tanδ 0.123 0.138 0.133 0.125 0.124 0.125 0.127 Resin 1: Coumarone Indene Resin 60, Kolon products

From the results of Table 1, when a low molecular weight resin is added to the diene-based silica rubber compound, the overall modulus is reduced and the wet grip performance is improved as in Comparative Example 2, but the rolling resistance performance is sharply worsened.

On the other hand, when using the reactive resin added maleic acid to other α-methylstyrene, styrene and indene in the present invention, 100% modulus is slightly lower but 300% modulus is not significantly different compared to Comparative Example 1, which is a non-reactive resin It is clearly distinguished from the addition of 1 (coumarone indene resin).

However, when using the reactive resin at 20 parts by weight as in Comparative Example 3, 0 ℃ tan δ is increased, which is advantageous for wet grip performance, but 60 ° C. tan δ is also increased, so that the rotational resistance performance (low fuel consumption performance) is lowered. Is preferably contained in 1 to 15 parts by weight.

As described in detail above, when 3-octanoylthio-1-propyltriethoxysilane is introduced as a novel coupling agent while including precipitated silica as a reinforcing agent according to the present invention, TESPT or TESPD having a conventional mercaptoalkoxysilane group It is useful as a tire tread rubber because it can solve the scoping problem caused by the use of a coupling agent such as this to secure the scoping stability and also improve the low fuel consumption performance by inducing a highly reactive monosulfide bond with the rubber. Do.

Claims (2)

In the rubber composition for tire tread consisting of a diene silica compound rubber, A rubber composition for a tire tread, comprising 1 to 15 parts by weight of a resin containing a -methyl styrene, styrene and indene as a reactive resin, and maleized with maleic acid having an indene group as a reactive group based on 100 parts by weight of the raw rubber. The rubber composition for tire treads according to claim 1, wherein the reactive resin is included in an amount of 3 to 10 parts by weight based on 100 parts by weight of the raw material rubber.