KR100667868B1 - Tire tread rubber composition with abrasion resistance and improved snow performance - Google Patents

Abstract

Provided is a tire tread rubber composition, which has improved quality on snow and wear resistance while maintaining overall physical properties including tensile property. The tire tread rubber composition comprises base rubber and additives. The base rubber comprises solution polymerized styrene-butadiene rubber having a styrene content of 15-25 wt% and a vinyl content of 55-70 wt%. The above solution polymerized styrene-butadiene rubber is obtained by modifying the terminal groups of a solution polymerized styrene-butadiene rubber with a benzophenone-based modifier into hydroxyl groups, and by coupling the modified rubber with a halogen-substituted multi-valent reactive polysiloxane compound.

Description

TIRE TREAD RUBBER COMPOSITION WITH ABRASION RESISTANCE AND IMPROVED SNOW PERFORMANCE

The present invention relates to a tire tread rubber composition having improved abrasion resistance and snow performance, and more particularly, to a solution-polymerized styrenebutadiene rubber end group using a benzophenone-based modifier as a raw material rubber to a hydroxyl group, and substituted with halogen. The present invention relates to a tire tread rubber composition having improved wear resistance and snow performance by containing a solution-polymerized styrene-butadiene rubber coupled using a reactive polysiloxane compound.

Among the components of the tire, the tread is an important part that expresses the required characteristics of the tire. Influencing the performance of the tread, in addition to the pattern effect, structural factors, the effect of the tread rubber composition is also an important factor.

In general, tire wear is a phenomenon in which the surface of the tread rubber which is grounded to the ground due to frictional force between the tire and the road surface is worn out. This wear phenomenon includes the lateral force when turning a curve while driving and the final force when driving and braking. It is caused by various factors, and wear of tires also has a great influence on the life and braking performance of the tires, and therefore, wear resistance should be excellent in terms of safe running and tire cost reduction.

In order to improve such wear resistance, carbon black is generally applied. However, the reinforcing performance of rubber by carbon black as a reinforcing agent is considered to be the dominant factor in terms of specific surface area (particle diameter) and structure of carbon black. There are many varieties of carbon black. When mixing with rubber components, various kinds of carbon blacks are selected and used according to the application characteristics.For example, in the case of harsh driving conditions such as tire treads, hard carbon blacks requiring high wear resistance are applied. Doing.

However, when hard carbon black having a large specific surface area and a large structure is applied, wear resistance is increased, but heat generation is increased.

As a method to solve this problem, a compound that satisfies the conditions of use and required properties using two or three kinds of polymer blends and a single or different types of carbon black in the tread rubber composition was used. However, there is a limit to controlling the trade-off characteristics of durability, ride comfort, noise and vibration, steering stability, and wear resistance.

On the other hand, as a conventional technique for improving the braking distance and snow performance, mainly applied to the tread rubber composition for snow tires, such as active carbon, calcium carbonate, hardened rubber powder, calcined shells, leather grinding and fiber grinding, Application of fiber such as short cords such as cellulose and aramid, application of special rubber such as silicone and butyl polymer, application of special chemicals such as silylating agent, foaming agent, foaming agent, and tread structure change to double-layer (two types) Compound application). However, these conventional techniques improve the braking distance and snow performance, but there is a problem that can negatively affect the mechanical properties of the tread rubber composition.

Generally, the raw rubber of the tread rubber composition is composed of a mixture of natural rubber / emulsion polymerization styrenebutadiene rubber / butadiene rubber. Emulsion-polymerized styrene-butadiene rubber has a favorable wettability but has a disadvantage in snow performance. Natural rubber and butadiene rubber has a low glass transition temperature, which has a favorable snow performance but has a disadvantage in wettraction. Thus, it is not possible to improve snow performance in a typical polymer blend system without sacrificing wet traction characteristics.

In order to solve these problems, various molecular designs are possible for solution-polymerized styrene-butadiene rubber using alkyl lithium initiators to control microstructures such as styrene content, vinyl content, and molecular weight distribution. Methods of introducing various functional groups have been continuously developed to improve reactivity, but have not yet obtained a clear result.

SUMMARY OF THE INVENTION An object of the present invention is to provide a tire tread rubber composition having improved snow performance and wear resistance while maintaining various physical properties such as tensile properties in order to satisfy tire use conditions and various required characteristics.

The tire tread rubber composition according to the present invention is a styrene in which a solution-polymerized styrenebutadiene rubber end group is modified with a hydroxy group using a benzophenone-based modifier as a raw material rubber, and is coupled using a polyvalent reactive polysiloxane compound substituted with halogen. The content of 15 to 25% by weight, the vinyl content of 55 to 70% by weight characterized in that it comprises a solution-polymerized styrene butadiene rubber.

The solution-polymerized styrene-butadiene rubber used in the rubber composition of the present invention has a benzophenone-based modification of 0.1-1.5 mole per 1 molecule of the solution-polymerized styrene-butadiene rubber having a styrene content of 15 to 25% by weight and a vinyl content of 55 to 70% by weight. A solution-polymerized styrene-butadiene rubber in which the end group of the rubber is transformed into a hydroxyl group by coupling with a halogen and a polyvalent reactive polysiloxane compound substituted with halogen, which has a hydroxyl group at the end of the rubber and thus has a polarity in the raw material rubber. The polarity of these rubbers increases the reactivity with reinforcing fillers, especially silicas, which are constantly increasing in use, with 70-80% hydroxyl group strain being best in affinity with reinforcing fillers silica. Finally, it has the effect of improving braking force and snow performance.

If the amount of the benzophenone-based modifier is less than 0.1 mole per molecule of solution-polymerized styrene-butadiene rubber, it is not preferable because no sufficient hydroxy group is deformed, and if it exceeds 1.5 mole, the deformation rate of hydroxy group of the styrene-butadiene rubber end group It is not desirable that there is no difference for.

As the benzophenone-based modifier, for example, 4,4'-bis- (diethylamino) benzophenone or 3,3 ', 4,4'-benzophenone tetracarboxylic dihydride can be used.

The halogen-substituted polyvalent reactive polysiloxane coupling agent has a molecular weight of 400 to 100,000, and is a polyvalent reactive polysiloxane compound substituted with halogen, and the structural formula is represented by the following general formula (1).

Y- {C (R3) (R4)} _c -Si (R1) (R2)-{0-Si (R1) (R2)} _d- {C (R3) (R4)} _c -Y ---- -------(One)

In formula (1), Y is (X) _a (R) _b Si or (X) _a (R) _b Si or (X) _a (R) B _c or (X) _e (R1) _f Bz-X X is a halogen atom such as one or more fluorine, chlorine, bromine or iodine, R is a lower alkyl group having 25 or less carbon atoms, including methyl, ethyl, propyl, etc., Bz-X is benzylhalogen, R1 , R3, R4 is the same as R, or a hydrogen atom, an alkyl group substituted by halogen or a silane group substituted by halogen, R2 is equal to X or R1, or (X) _g (R3) _h C- {C (R3 ) (R4)} _c-1 , a is 1 to 3, b is 0 to 2, a + b = 3, c is 1 to 1000, d is 1 to 50000, e and f are each 0 ˜4, e + f = 4, g and h are each 0 to 3, and g + h = 3.

The polyvalent reactive polysiloxane coupling agent has a high solubility in organic solvents, and has a polyvalent reactor, which has high reactivity with living polymer ions, excellent thermal stability, and includes an active leaving group, thereby maintaining a living state during anionic polymer reaction. When added to a polymer solution, by participating in a smooth substitution reaction under mild reaction conditions, not only the third functional group can be introduced at the end of the polymer composed of repeating units of a certain monomer, but also organic and inorganic compounds are combined in one polymer. There is an advantage to produce a hybrid polymer. In addition, it is a polyvalent reactive polysiloxane compound that can enhance the compatibility with the inorganic filler and reinforcing agent used together in the rubber compounding, and can provide an elastomer modified with organic silicone.

The polyvalent reactive polysiloxane compound used in the present invention may be prepared by reacting an organic polysiloxane having a hydrogen-silicon bond or an organic polysiloxane having a vinyl-silicon bond with an unsaturated compound substituted with a halogen group or a hydrosilane compound substituted with a halogen group. .

The tread rubber composition of the present invention preferably uses the solution-polymerized styrene-butadiene rubber alone as the raw material rubber, but 50-90 parts by weight of the solution-polymerized styrene-butadiene rubber in 100 parts by weight of the raw material rubber, natural rubber, emulsion-polymerized styrene It may comprise 10 to 50 parts by weight of one or more of butadiene rubber, butadiene rubber and butadiene rubber / syndiotactic polybutadiene composite (composite).

In the rubber composition of the present invention, when the mixed rubber of the solution-polymerized styrene-butadiene and the other synthetic rubber is used as the raw material rubber, natural rubber and butadiene rubber have a low glass transition temperature, but snow performance is advantageous, but wet traction is disadvantageous. In addition, the emulsion-polymerized styrene-butadiene rubber has a favorable wet traction but has a disadvantage in snow performance, but the butadiene rubber / syndiotactic polybutadiene composite has a dispersibility but a disadvantage in wear resistance, so that the at least one rubber component is By employing the combination in one content range, each disadvantage can be compensated.

In addition, the butadiene rubber / syndiotactic polybutadiene composite has a pattern viscosity of 30 to 70, the sheath content of 98% by weight or more, the content of syndiotactic polybutadiene (SPB) is preferably in the range of 1 to 40% by weight. In addition, the types and properties of butadiene rubber / syndiotactic polybutadiene composite which can be preferably used in the present invention are shown in Table 1 below.

Table 1

In the present invention, carbon black and / or silica commonly used as a reinforcing agent may be added to the rubber composition in a conventional amount. Carbon black) and Table 3 (silica).

TABLE 2

TABLE 3

In addition, the rubber composition of the present invention may include other additives and compounding agents used in conventional tire tread rubber compositions.

The present invention can be understood in more detail by the following examples and comparative examples, the following examples are only for illustrating the present invention, and are not intended to limit the protection scope of the present invention.

Example

1) preparation of test rubber

  The properties of the raw material rubber of the test rubber compound are shown in Table 4 below, and the compounding specifications are shown in Table 5 below.

Table 4

Table 5

(Unit: parts by weight)

⑤ Emulsion polymerization styrene butadiene rubber: SBR-1500 of Kumho Petrochemical.

2) Physical property result

  Vulcanization conditions and tests of the blended rubber was tested according to ASTM standards, the results are shown in Table 6 below.

Table 6

As can be seen from the results of the physical property test of Table 6, the solution-polymerized styrene butadiene rubber of the hydroxy group modification ratio of the solution-polymerized styrene butadiene rubber and the coupling of the polyvalent reactive polysiloxane compound substituted with halogen is within the scope of the present invention. When the rubber specimen of the used example is compared with the rubber specimen of the comparative example which uses the conventional emulsion-polymerized styrene-butadiene rubber as the raw material rubber, the tensile properties are maintained at the same level or higher, and the dispersibility and the wet skid resistance are improved. Performance has been improved.

The tire tread rubber composition of the present invention shows that the wear resistance and the snow performance are improved while the tensile properties and the wear characteristics are maintained at the same level.

Claims (7)

In a tire tread rubber composition comprising a raw material rubber and an additive, a polyvalent reactive polysiloxane compound substituted with a halogen-substituted solution-polymerized styrene-butadiene rubber terminal group using a benzophenone-based modifier as a raw material rubber and a halogen group A tire tread rubber composition comprising a solution-polymerized styrene-butadiene rubber having a styrene content of 15 to 25% by weight and a vinyl content of 55 to 70% by weight. The tire tread rubber composition according to claim 1, wherein the hydroxyl group strain of the solution-polymerized styrene-butadiene rubber is 70 to 80%. 50 to 90 parts by weight of the solution-polymerized styrene-butadiene rubber, natural rubber, emulsion-polymerized styrene-butadiene rubber, butadiene rubber and butadiene rubber / syndiotactic polybutadiene compound in 100 parts by weight of the raw material rubber. A tire tread rubber composition comprising 10 to 50 parts by weight of one or more of the jits. The benzophenone-based modifying agent according to claim 1 or 2, wherein the benzophenone-based modifier is 4,4'-bis- (diethylamino) benzophenone or 3,3 ', 4,4'-benzophenone tetracarboxylic dihydride. A tire tread rubber composition, characterized in that it is used as a lide, and 0.1 to 1.5 mol per molecule of solution-polymerized styrene-butadiene rubber. The method of claim 1 or 2, wherein the polyvalent reactive polysiloxane compound reacts an organic polysiloxane having a hydrogen-silicon bond or an organic polysiloxane having a vinyl-silicon bond with an unsaturated compound substituted with a halogen group or a hydrosilane compound substituted with a halogen group. It is manufactured by making it and the molecular weight is 400-100,000, The tire tread rubber composition characterized by the above-mentioned. The tire tread rubber composition according to claim 5, wherein the polyvalent reactive polysiloxane compound is represented by the following formula: Y- {C (R3) (R4)} _c -Si (R1) (R2)-{0-Si (R1) (R2)} _d- {C (R3) (R4)} _c -Y ---- -------(One) In formula (1), Y is (X) _a (R) _b Si or (X) _a (R) _b Si or (X) _a (R) B _c or (X) _e (R1) _f Bz-X Wherein X is a halogen atom, R is a lower alkyl group with 25 or less carbon atoms, Bz-X is benzylhalogen, and R1, R3, R4 are the same as R, or a hydrogen atom, an alkyl group substituted with halogen or halogen Is a substituted silane group, R2 is equal to X or R1, or (X) _g (R3) _h C- {C (R3) (R4)} _c-1 , a is 1 to 3, b is 0 to 2, a + b = 3, c is 1 to 1000, d is 1 to 50000, e and f are each 0 to 4, e + f is 4, g and h are each 0 to 3, g + h = 3. According to claim 1 or 2, wherein the butadiene rubber / syndiotactic polybutadiene composite has a viscosity of 30 to 70, the sheath content of 98% by weight or more, the content of syndiotactic polybutadiene 1 to 40% Tire tread rubber composition, characterized in that the range.