KR101910178B1 - Rubber composite for tread part of tyre - Google Patents

Abstract

The present invention discloses a tire tread rubber composition. The tire tread rubber composition according to the present invention comprises silica or carbon black as a reinforcing material to be mixed with raw rubber, and comprises organosilane represented by chemical formula 1 for coupling of the raw rubber with the reinforcing material. Accordingly, the crosslinking density with the reinforcing material filler is increased by the organosilane, the activity of the specific functional group of the reinforcing material is prevented to enhance the dispersibility, thereby enhancing the low fuel efficiency performance and securing the workability and reinforcement.

Description

Technical Field [0001] The present invention relates to a rubber composition for tread part,

The present invention relates to a tire tread rubber composition, and more particularly, to a tire tread rubber composition capable of increasing cross-linking density with an organosilane and reinforcing a low fuel consumption performance and ensuring workability and reinforcement property .

Recently, studies are underway to reduce rolling resistance by using silica and silane coupling agents to reduce the rolling resistance of tread rubber of passenger car tires.

Generally, the rubber composition used for a tire tread is improved in heat generation characteristics depending on the type and amount of carbon black and silica, but the value of tan delta (tan delta @ 70 DEG C), which is an index of rolling resistance, There is a tendency.

Also, when the value of tan delta (tan? @ 70 占 폚), which is an index of the rolling resistance, is increased, the tan delta (tan? @ 0 占 폚) value of the braking performance is lowered.

As the affinity of the styrene-butadiene rubber blend with the silica component is decreased, the rubber composition mainly used is not dispersed to the maximum and the physical properties of the rubber composition can not be exhibited at the maximum.

Various silane coupling agents have been developed to solve these problems, and silane coupling agents have been developed as reinforcing agents.

(Bis (triethoxysilyl-propyl) -tetrasulfide; hereinafter referred to as TESPT) is used as the most widely used silane coupling agent, but in recent years, a mercapto silane excellent in performance has been used as the soybean .

These mercaptosilanes are monosulfide silanes, which increase the crosslink-density between the stiffener filler and the polymer as compared to TESPT, which is a polysulfide silane, Hysteresis) to improve fuel efficiency performance.

However, the mercapto group (-SH) of mercapto silane is excellent in reactivity with the styrene-butadiene rubber, so that the scorch time is shortened when the tire rubber composition is blended, and the processability is lowered. In addition, Time is exceeded, and the reinforcing property also falls.

That is, since rubber for tire receives heat history continuously from mixing (maximum 160 ° C) to vulcanization (maximum 185 ° C), the rubber compound should have thermal stability. Especially, when the reaction between silane and polymer occurs, , The tensile properties and the abrasion performance of the tire are lowered because of the lack of the thermal stability of the conventional mercapto silane, so that the bonding of the silane and the polymer in the rubber compound occurs beforehand, And the reinforcing property is lowered.

Accordingly, a technical problem to be solved by the present invention is to provide a tire tread rubber composition which can increase cross-linking density with a reinforcing material filler by an organosilane and improve a low fuel consumption performance and at the same time ensure reinforcement workability, reinforcing property, .

In order to solve the above-mentioned technical problem, the present invention is characterized in that it comprises silica or carbon black as a reinforcing material to be mixed with a raw material rubber, and contains organosilane of the following formula (1) By weight based on the total weight of the tire tread rubber composition.

≪ Formula 1 >

(R1 is a hydro-alkoxy having 1 to 8 carbon atoms (C1 to C8), R2 is an alkyl alkylene group having 1 to 12 carbon atoms (C1 to C12) R3 is an alkyl (Alkyl) group having 1 to 12 carbon atoms, and R4 is a thioic group having 1 to 12 carbon atoms)

According to another embodiment of the present invention, the organosilane may be one obtained by dehydration condensation of a silane of Formula 2 and a carboxy group of 1 to 12 carbon atoms.

 (2)

According to another embodiment of the present invention, the organosilane may be a compound represented by the general formula (3).

(3)

According to the tire tread rubber composition of the present invention, the cross-linking density with the reinforcing material filler is increased by the organosilane and the activity of the specific functional group of the reinforcing material is prevented to improve the dispersibility, thereby improving the low fuel consumption performance and securing the workability and reinforcement There is an effect that can be done.

It is to be noted that the technical terms used in the present invention are used only to describe specific embodiments and are not intended to limit the present invention, and the technical terms used in the present invention are defined in the present invention in a different sense It is to be understood that the present invention should not be construed in an overly broad sense or in an excessively reduced sense by a person having ordinary skill in the art to which the present invention belongs.

In addition, when a technical term used in the present invention is an erroneous technical term that does not accurately express the concept of the present invention, it should be understood that technical terms that can be understood by a person skilled in the art are replaced with a technical term. Shall be construed in accordance with pre- or post-context, and shall not be construed in an excessively reduced sense.

Furthermore, the singular expressions used in the present invention include plural expressions unless the context clearly dictates otherwise. In the present invention, terms such as "comprising" or "comprising" and the like should not be construed as encompassing various elements or various steps of the invention, Or may further include additional components or steps.

The tire tread rubber composition according to the present invention comprises silica or carbon black as a reinforcing material to be blended with a raw material rubber and has an organosilane structure according to the following formula (1) for coupling between a raw rubber and a reinforcing material.

≪ Formula 1 >

Wherein R 1 is a hydroalkoxy of 1 to 8 carbon atoms (C 1 to C 8), R 2 is an alkylideneediamine of 1 to 12 carbon atoms (C 1 to C 12), alkyl R3 is an alkyl group having 1 to 12 carbon atoms, and R4 is a thio group having 1 to 12 carbon atoms. The term " alkyl group "

Particularly, R4 is a constituent element to be substituted for preventing degradation of reinforcing property by a mercapto group, and the organosilane includes a silane of Formula 2 and a carboxy group of 1 to 12 carbon atoms Can be prepared by dehydration condensation of the compound.

Further, the raw material rubber is not particularly limited to natural rubber or synthetic rubber used for the tire tread, but may be mixed according to the characteristics of the tire.

In addition, the reinforcing material may be silica or carbon black, and may exhibit various sizes of particles and characteristics in the form of powders. The organosilane used for coupling the raw rubber to the reinforcing material may be represented by the general formula , Which may be obtained by dehydration condensation of silane of Formula 2 and 1 to 12 carbon-carbon compounds (Carboxyl Group).

 (2)

For example, as shown in Scheme 1, a dehydration condensation reaction is performed in a strong acid environment such as sulfuric acid or nitric acid to form a structural formula of Formula 2. Thus, as shown in Reaction Formula 2, By the dehydration condensation reaction with a compound (carboxyl group), an organosilane example of the formula (3) according to the present invention can be prepared. Thus, the activity of a specific functional group of the reinforcing material, for example, the active silanol group of silica, , And the dispersibility can be improved.

In the following reaction scheme 1, two molecules of -Si (EtO) ₃ and two nonylethylenediamine alcohols cause direct condensation upon heating in a high concentration of nitric acid solvent to produce two molecules of EtOH and nonyl ethlenediamine silane, When the reaction temperature is higher than the above temperature, the reaction with the peroxide impurities of the solvent may form a disulfide to lower the dispersibility of the silane, and the LRR effect may decrease. When the reaction temperature is less than 50 ° C, the reaction rate may be drastically decreased.

<Reaction Scheme 1>

<Reaction Scheme 2>

The following reaction scheme 2 is a dehydration condensation reaction with octyl-carboxylic acid.

Reaction formula 1 and Reaction formula 2 are preferably performed continuously, and reverse reaction and disulfide formation may occur during long-term storage after reaction 1, so that reaction formula 1 and reaction formula 2 can be performed within at least one hour.

Example  And Comparative Example

The rubber compound was mixed and extruded in the same composition as shown in Table 1 to prepare a tire tread rubber.

Item Comparative Example 1 Comparative Example 2 Comparative Example 3 Example SBR (styrene-butadiene rubber) 96 96 96 96 BR (butadiene rubber) 30 30 30 30 Silica 80 80 80 80 Silane coupling agent
8 8 8 8 Carbon black 5 5 5 5 Zinc oxide 3 3 3 3 Stearic acid 2 2 2 2 Antioxidant 1.5 1.5 1.5 1.5 Sulfur 1.5 2.1 2.1 2.1

Silica having a surface area of 200 ± 5 m ² / g was used as the BET measurement value. As the silane coupling agent, Comparative Examples 1 and 2 used Bis [3- (triethoxysilyl) propyl] Tetrasulfide (TESPT),

Comparative Example 3 used mercaptopropyltriethoxysilane, Example used alkoxyethylenediamine silane represented by Formula 3, and carbon black had a surface area of 80 ± 5 m 2 / g as measured by N 2 SA.

Experimental Example

The properties of Mooney viscosity, tensile strength, dynamic viscoelasticity (DMA) and wear resistance (Din Abrasion) of each tire tread rubber specimen prepared in Table 1 were measured according to ASTM regulations, Table 2 summarizes the results.

Item Comparative Example 1 Comparative Example 2 Comparative Example 3 Example Mooney viscosity MV @ 100 ℃ 93 118 115 81 T05 19 18 12 18
Tensile properties Hardness 69 66 69 69 300% -M 102 113 92 103 T.S 179 117 111 180 E.B. 485 306 302 488
DMA Tg -25 -25 -25 -25 tan? @ 0 C (index) 100 96 94 106 tan? @ 70 占 (index) 100 92 120 132 Religion loss (index) 100 86 81 101

As can be seen from the test results in Table 2, the tire tread rubber according to the present invention has similar Modulus, TS and EB characteristics as those of the conventional silane coupling agent, but the tanδ @ 0 ° C , And the workability index MV100 deg. Is lowered, and the workability is excellent, and it can be seen that tan? @ 70 deg., Which is an index of rolling resistance, is greatly improved. Here, index is a relative value, Is defined as 100, and comparative examples 2, 3, and corresponding values of the embodiment are described relatively).

Here, T05 is defined by the Mooney viscosity measurement at 125 DEG C as follows.

Initial viscosity: Initial torque value before sample is completely inserted

Mv @ 125 ° C: 125 ° C Viscosity at Mooney viscosity measurement Minimum torque value

ML: Viscosity at 5 ° C Mooney viscosity measurement Time (min) when having minimum torque value

x unit: Time (min) when the torque increases x% at 125 ° C.

T05 (Mooney scorch time): time in ML + 5unit (min)

For stable vulcanization in tire production, T05 is generally more than 15, and when it is less than 15, the thermal stability is lowered and the tensile properties and abrasion performance tend to decrease significantly.

As a result, it can be seen that the rubber composition according to the present invention improves the low workability and poor wear performance which are caused by the conventional silane coupling agent and improves the rolling resistance (LRR) characteristic compared to the conventional silane TESPT.

Claims (3)

delete delete A tire tread rubber composition comprising silica or carbon black as a reinforcing material to be blended with a raw material rubber, and comprising organosilane represented by the following formula (3) for coupling between a raw rubber and a reinforcing material.
(3)