KR102289643B1 - Rubber composition for tire tread - Google Patents

Abstract

The present invention relates to a rubber composition for a tire tread, and specifically, to a rubber composition for a tire tread including an amide silane compound represented by chemical formula 1, and a tire including the same. The present invention can improve workability and reinforcing performance.

Description

Rubber composition for tire tread

The present invention relates to a rubber composition for a tire tread, and more particularly, in a conventional rubber composition for a tire tread, comprising an amide silane compound having improved processability and reinforcing properties, which are disadvantages of mercaptosilane used as a reinforcing agent It relates to a rubber composition for a tire tread and a tire comprising the same.

The tire tread is a part that comes in direct contact with the ground while the vehicle is moving, and must have excellent characteristics such as abrasion resistance, rolling resistance, and tensile strength that affect fuel efficiency.

Among the various additives used in the tire tread rubber composition, carbon black was used as the main filler to improve abrasion resistance and tensile strength, but silica was mainly used instead of carbon black to improve low fuel efficiency and wet road braking performance. did it

When the silica is used as a reinforcing agent in a tire rubber composition, there are advantages of improving wet road friction and reducing rolling resistance, but miscibility with non-polar rubber is poor due to the strong polar group (-OH), and It is known that the disadvantage is that it is disadvantageous in terms of processing due to strong cohesive force.

In order to solve this problem, Korea Registered Patent No. 10 using an amide-modified fatty acid derivative as a processing aid together with Si69, which is bis(triethoxysilylpropyl)tetrasulfide (hereinafter TESPT), as a coupling agent. As in -1457864, a method using a silane coupling agent has been devised and TESPT is well used as a silane coupling agent, but recently, as disclosed in Japanese Patent No. 5563298, it reduces the emission of volatile organic compounds (VOC), and It is possible to improve dispersibility, and there is a trend to use mercaptosilane, which is excellent in rotation resistance, heat generation characteristics, and abrasion performance.

In the conventional tire manufacturing, the heat treatment time required to reach a temperature at which the unvulcanized rubber composition is cured prior to the vulcanization process such as press work by compounding the rubber composition and then aging is referred to as scorch time. , If the scorch time is long, the shape of the rubber may collapse before the composition is vulcanized, and if the scorch time is short, accurate processing operations, particularly accurate vulcanization time measurement, are difficult, and processing before the vulcanization process Vulcanization occurs during operation, which reduces plasticity and increases elasticity, making the product impossible to process. Therefore, an appropriate scorch time is required for physical properties and processability.

In the case of the mercapto group (-SH) of the mercaptosilane, the reactivity with the filler and the organic polymer is so high that it is known that the reactivity with the filler and the organic polymer is 100%. In this case, it is not easy to use the mercaptosilane, and the mercaptosilane is mixed with the polymer of the filler and other components due to the short scorch time with the uncured filled elastomer, and the uncured elastomer As the extrusion molding and premature crosslinking or formation of a compound having a high viscosity are formed, there is a problem in that the processability and reinforcing properties of the product are deteriorated.

Therefore, the present invention was created in view of the problems of the prior art, and it is possible to improve workability and reinforcing properties by improving the workability and reinforcing properties lowered due to the 100% reaction of mercaptosilane with the polymer. It is to provide a rubber composition for a tire tread that can be used.

In order to achieve the above object, the present invention provides a rubber composition for a tire tread that supplements processability and reinforcing properties, which are disadvantages of conventional mercaptosilane, for a tire tread. 1 to 15 parts by weight of the coupling agent, preferably 5 to 10 parts by weight, if the content is less than 1 part by weight, there may be problems in fairness and rotational resistance characteristics, conversely, if it exceeds 15 parts by weight, the physical properties As well as falling, it may cause a problem in the rolling resistance characteristics.

There is provided a rubber composition for a tire tread comprising an amide silane compound represented by the following Chemical Formula 1 in which a main chain is a single bond as a silane coupling agent in the rubber composition for a tire tread.

[Formula 1]

In Formula 1, R ₁ and R ₂ are an alkoxy group having 1 to 15 carbon atoms, R ₃ and R ₄ are an alkane group having 1 to 5 carbon atoms, x is an integer of 1 to 5, R ₅ is an alkane group having 1 to 20 carbon atoms.

When silane is combined with silica, _{by limiting the R 3} to R ₅ substituents of Formula 1 to an alkane group, the alkane group of the silane blocks the -OH group located on the surface of the silica to prevent the silica from re-aggregating , is effective in improving the dispersibility without the need for a separate addition such as a silica dispersant at the time of bonding.

The silane coupling agent of the present invention may be a silane compound represented by the following formula (2) among the amide silane compounds of the formula (1).

[Formula 2]

(EtO in Formula 2 means an ethoxy group.)

Through the rubber composition for tire tread according to the present invention, the scorch time is shortened due to 100% reaction of the existing mercaptosilane with the polymer while maintaining the physical properties of the conventional tire, thereby improving the workability and reinforcing properties. .

The present invention provides a rubber composition for a tire tread with improved processability and reinforcing properties in order to improve the above problems. The present invention has been carried out as follows, but is not limited thereto.

The rubber composition for a tire tread of the present invention includes an amide silane compound represented by the following Chemical Formula 1 as a silane coupling agent.

[Formula 1]

In Formula 1, R ₁ and R ₂ are an alkoxy group having 1 to 15 carbon atoms, R ₃ and R ₄ are an alkane group having 1 to 5 carbon atoms, x is an integer of 1 to 5, and R ₅ is an alkoxy group having 1 to 5 carbon atoms. It is an alkane group of 20.

The silane coupling agent used as the reinforcing agent of the present invention may be a silane compound represented by the following formula (2) among the amide silane compounds of the formula (1).

[Formula 2]

(EtO in Formula 2 means an ethoxy group.)

In addition, the rubber composition for a tire tread according to the present invention includes, as raw rubber, natural rubber, synthetic rubber, or a mixture thereof.

In the rubber composition for a tire of the present invention, the type of the synthetic rubber is not particularly limited, and for example, styrene-butadiene rubber (SBR), butadiene rubber (BR), butyl rubber, emulsion polymerization styrene-butadiene rubber (E-SBR), solution polymerization styrene butadiene rubber (S-SBR), epichlorohydrin rubber, nitrile rubber, hydrogenated nitrile rubber, brominated polyisobutyl isoprene-co-paramethylstyrene styrene; BIMS) rubber, urethane rubber, fluororubber, silicone rubber, styrene ethylene butadiene styrene copolymer rubber, ethylene propylene rubber, ethylene propylene diene monomer rubber, hypalon rubber, chloroprene rubber, ethylene vinyl acetate rubber and acrylic rubber, etc. can

The rubber composition for a tire of the present invention may contain 1 to 15 parts by weight, preferably 5 to 10 parts by weight, of the silane coupling agent, based on 100 parts by weight of the raw rubber, but if less than 1 part by weight, fairness and rotation There may be a problem with the resistance characteristic, and on the contrary, if it exceeds 15 parts by weight, not only the physical properties decrease, but also a problem with the rotation resistance characteristic may occur.

The rubber composition for a tire tread of the present invention may further include carbon black and silica.

In the rubber composition for a tire tread of the present invention, it is preferable to use particles having a specific surface area of 140 m 2 /g or less for the carbon black in terms of dispersion and wear.

In the rubber composition for a tire tread of the present invention, the silica may have a BET surface area of 90 to 250 m 2 /g.

[Examples and Comparative Examples]

Compositions of Examples and Comparative Examples carried out in the present invention include Table 1 below.

1) SBR: styrene content 25%, butadiene content 63%

2) BR: KKPC High-cis Polybutadiene Rubber, product name KBR01

3) Silica: Silica with a nitrogen adsorption specific surface area of 200 m ² /g

4) Silane coupling agent 1: Bis-(triethoxysilyl-propyl)-tetrasulfide (TESPT, product name: Si-69)

5) Silane coupling agent 2: Mercaptosilane, 3-(triethoxysilyl)propanethiol, reaction products with ethoxylated C13-alcohol

6) Silane Coupling Agent 3: A compound represented by Formula 2 below (Manufacturer: Jianghan Fine Chemical Co., LTD, Product Name: JH-S-1987C Silane Coupling Agent)

The silane coupling agent (JH-S-1987C Silane Coupling Agent) used in the present invention has an amide structure due to the reaction of a material containing a _{carbonyl group (R-COOH) with a material containing an amine (R-NH 2 ) in the synthesis process} is produced, the synthetic yield is about 5% better than that of mercaptosilane, and it is easy to make, and the thermal stability is superior to that of the existing mercaptosilane.

[Formula 2]

1) Carbon black: Carbon black with DBP surface area of 100m2/g

2) Zinc Oxide: Zinc Oxide

3) Stearic acid: ELOFAD TH100 from LG Household & Health Care

4) Anti-aging agent: N-(1,3-dimethylbutyl)-N'-phenyl-P-phenylenediamine (product name: KUMANOX 13)

5) Sulfur: Miwon Chemical (MIDAS-101)

6) DPG: N,N'-diphenylguanidine (N,N'-diphenylguanidine)

For the rubber compositions prepared in Examples and Comparative Examples, the physical properties of Mooney viscosity, tensile properties, dynamic viscoelasticity (DMA) and abrasion (Din Abrasion) were measured according to ASTM related regulations, and the results are shown in Table 2 below. shown in

Among the above Mooney viscosity, MV@100℃ is when mixing rubber is put between the upper and lower rotors with several grooves in the circumferential direction and rotated at 100℃, shear behavior is formed between the rotors and the resulting torque resistance), and the lower the viscosity value, the better the processability and processability.

Among the Mooney viscosity, MV@125° C. means a viscosity minimum torque value measured at 125° C. Mooney viscosity.

T05 (Mooney scorch time) of the Mooney viscosity refers to the time (min) when ML + 5 units, and the ML refers to the time (min) when the viscosity has the minimum torque value at 5 ° C. Mooney viscosity measurement .

Hardness is a real value of a rubber specimen and was measured according to ASTM standards, and the higher the value, the better the hardness.

300%-M (Modulus) is the tensile strength at 300% elongation of a rubber specimen, measured according to ASTM standards, and the higher the value, the better the tensile strength.

T.S (tensil strength) is a value obtained by dividing the maximum tensile load until fracture of the test piece by the cross-sectional area of the test piece before the test in a tensile test of a material.

E.B is the elongation ratio at which the material is stretched during the tensile test of the material. The larger the number, the better the elongation.

Tg means the temperature at which the polymer branches of the polymer material are activated and start to move due to the temperature.

tanδ@ 0℃ is tandelta (tanδ℃, measured at 11Hz by a DMA (Dynamic Mechanical Analysis) tester), which is an index of braking performance, and is used as an index of wet road braking performance. It means excellent performance.

tanδ@ 70℃ is the result of tan delta (tanδ℃, measured at 11Hz by DMA (Dynamic Mechanical Analysis) tester), which is an index of rolling resistance, and is used as an index of the rolling resistance performance. means excellence.

DIN abrasion test is an evaluation item for predicting tire wear, and the lower the number, the better the wear characteristics.

Referring to Table 2, the example using a rubber composition including amide silane according to the composition of Table 1 is a silane coupling agent that exhibits physicochemical properties according to the combination of silica and polymer, and is a conventional mercaptosilane (silane coupling agent). Compared with 2), it can be seen that the scorch time is longer and the workability is greatly improved, and the tensile properties such as modulus and TS characteristics are similar.

In particular, in processability, the lower the viscosity value of MV@100°C, which is the 100°C Mooney viscosity, which is used as the measurement standard, is advantageous in processability due to better flowability. It is necessary to maintain an appropriate viscosity value in consideration of

Accordingly, the rubber composition of Example, which is the compound formulation for tread of the present invention, exhibited a general standard specification of 160±15 at 300%-M, and EB also satisfies the minimum standard value of 300, as shown in Table 2 above. It was confirmed that it had similar physical properties to those of Comparative Examples, including hardness and reinforcing properties predicted from the 300%-M value.

At the same time, it was confirmed that the existing mercaptosilane, which had a Mooney viscosity of 80, could be lowered to a Mooney viscosity of 71, and the RR performance (rolling resistance) could be improved by 15% compared to the rubber specimen containing TESPT.

Therefore, by adding the silane coupling agent of the present invention to the rubber composition, it is possible to prepare a rubber composition for tire tread with improved processability and RR performance, which are major disadvantages of existing mercaptosilanes while maintaining physical properties.

Claims (6)

A rubber composition for a tire tread, comprising a raw rubber and a silane coupling agent, wherein the silane coupling agent is an amide silane represented by the following formula (1).
[Formula 1]

In Formula 1, R ₁ and R ₂ are an alkoxy group having 1 to 15 carbon atoms, R ₃ and R ₄ are an alkane group having 1 to 5 carbon atoms, x is an integer of 1 to 5, and R ₅ is an alkoxy group having 1 to 5 carbon atoms. It is an alkane group of 20. The rubber composition for a tire tread according to claim 1, wherein the amide silane is a compound represented by Chemical Formula 2 below.

In Formula 2, EtO means an ethoxy group. The rubber composition for a tire tread according to claim 1, wherein the raw rubber is natural rubber, synthetic rubber, or a mixture thereof. The rubber composition for a tire tread according to claim 1, wherein the silane coupling agent is included in an amount of 1 to 15 parts by weight based on 100 parts by weight of the raw rubber. A tire comprising the rubber composition of any one of claims 1 to 4. The tire according to claim 5, wherein the rubber composition is included in the tread portion of the tire.