JP2001081239A - Tread rubber composition for high-performance tire and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a treat rubber composition for high-performance tires high in gripping capability and wear resistance, and to provide a method for manufacturing the same. SOLUTION: This tread rubber composition for high-performance tires comprises 100 pts.wt. of rubber ingredients consisting of 10-40 wt.% of emulsion- polymerizer SBR(styrene-butadiene rubber) and 90-60 wt.% of solution- polymerizer SBR, 20-180 pts.wt. of a softener, and 30-150 pts.wt., of carbon black with its nitrogen adsorbing specific area (N2SA) being 100-300 m2/g. In this rubber composition, not less than 30 wt.% of the total proportion of the softener is mixed with every rubber incredient prior to the mixing of the carbon black and, furthermore, not less than 40 wt.% of the total proportion of the carbon black is mixed with the emulsion polymerizer SBR beforehand. A method of its manufacture is also provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tread rubber composition for a high-performance tire having improved abrasion resistance and grip properties at the same time, and a method for producing the same.

[0002]

2. Description of the Related Art In recent years, as the performance of automobiles has become higher, the characteristics required for tires have become higher.
For example, high grip performance and high abrasion resistance under high-speed running conditions can be achieved. In order to obtain a high gripping property, there is a method of using a styrene-butadiene rubber having a high styrene content in a tread rubber composition and highly filling a carbon black having a high reinforcing property and a softener. In this method, grip performance is improved, but there is a problem that wear resistance is reduced.

In order to simultaneously improve the wear resistance and grip of the tire, a method of blending a low molecular weight polymer with a rubber composition for a tread (Japanese Patent Laid-Open No. 1-197541).
JP-A-6-93136), a method of blending a specific carbon black into a rubber composition for a tread, and a method of blending a low-molecular-weight polymer and a specific carbon black into a rubber composition for a tread. (JP-A-9-143388) has been proposed.
However, the low molecular weight polymer has a problem in workability due to the viscous and sticky liquid.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a tread rubber composition for a high-performance tire which has both high grip performance and high abrasion resistance and has no problem in workability, and a method for producing the same. .

[0005]

According to the present invention, 100 parts by weight of a rubber component comprising 10 to 40% by weight of an emulsion-polymerized styrene-butadiene rubber, 90 to 60% by weight of a solution-polymerized styrene-butadiene rubber, and a softener are used. 20 to 180 parts by weight and a nitrogen adsorption specific surface area (N ₂ SA) of 100 to 300
In a rubber composition containing 30 to 150 parts by weight of m ² / g of carbon black, (1) 30% by weight or more of the total amount of the softener is mixed with each of the rubber components before mixing the carbon black. And (2) a tread rubber composition for a high-performance tire, wherein 40% by weight or more of the total amount of the carbon black is preliminarily mixed and dispersed in the emulsion-polymerized styrene-butadiene rubber. .

Next, a second invention relates to 10 to 40% by weight of an emulsion-polymerized styrene-butadiene rubber and a solution-polymerized styrene-butadiene rubber.
Rubber component 1 consisting of 90 to 60% by weight of butadiene rubber
In a method for producing a rubber composition comprising 00 parts by weight, 20 to 180 parts by weight of a softening agent, and 30 to 150 parts by weight of carbon black having a nitrogen adsorption specific surface area (N ₂ SA) of 100 to 300 m ² / g, (1) 3 of the total amount of the softener
Mixing 0% by weight or more of the rubber component of the emulsion-polymerized styrene-butadiene rubber and the rubber component of the solution-polymerized styrene-butadiene rubber, and (2) adding 40% by weight or more of the total amount of the carbon black to the softening agent. Mixing and dispersing in the mixed emulsion-polymerized styrene-butadiene rubber, (3) mixing a compounding agent other than sulfur and a vulcanization accelerator with the rubber component, and (4) mixing sulfur and the vulcanization accelerator with the ( Mixing the rubber composition obtained in the step 3) with the rubber composition,
This is a method for producing a tread rubber composition for high-performance tires.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The rubber components used in the present invention are emulsion-polymerized styrene-butadiene rubber and solution-polymerized styrene-butadiene rubber. Where the emulsion polymerized styrene
Butadiene rubber having a styrene content in the range of 15 to 50% by weight is used. On the other hand, various grades of solution-polymerized styrene-butadiene rubber having different styrene content and vinyl content are used. Preferably, the styrene content is 20 to 50% by weight and the vinyl content is 15 to 60% by weight. The glass transition temperature increases as the styrene content and vinyl content increase. As a result, the peak temperature of the main dispersion of the loss tangent also shifts to a higher temperature, the loss tangent value at 0 ° C. increases, and the grip performance increases. However, it is necessary to adjust the glass transition temperature so as not to lower the rolling resistance of the tire.

Next, the emulsion polymerized styrene-butadiene rubber is used in an amount of 10 to 40% by weight of the rubber component. The amount is 10
If the amount is less than 40% by weight, the abrasion resistance is poor.

Next, in the present invention, a softening agent is added to the rubber composition in an amount of 20 to 180 parts by weight based on 100 parts by weight of the rubber component.

The softening agent used herein is a petroleum softening agent such as a paraffinic softening agent, an aromatic softening agent or a naphthenic softening agent, as well as a coal tar softening agent such as coal tar and coumarone-indene resin and a fatty oil-based softening agent. It contains a softener, and further includes a synthetic resin softener such as dibutyl phthalate (DBT), dioctyl phthalate (DOP), and tricresyl phosphate (TCP), a liquid rubber, and an oligomer synthetic plasticizer.

If the softening agent is less than 20 parts by weight, sufficient grip properties cannot be obtained, while if it exceeds 180 parts by weight, the strength and abrasion resistance of the rubber composition are reduced. Preferably, 30 to 160 parts by weight of the softener is blended.

Next, the above-mentioned softener is used in 3 of the total amount of the rubber composition.
Before mixing with carbon black, 0% by weight or more is mixed with rubber components, that is, emulsion-polymerized styrene-butadiene rubber and solution-polymerized styrene-butadiene rubber. By pre-mixing the softener with the rubber component, the amount of the softener mixed at the same time when the rubber component is mixed with the carbon black can be reduced, and as a result, the dispersion of the carbon black in the rubber composition can be reduced. It is improved and wear resistance is improved.

Next, in the present invention, the rubber component 1 is added to the rubber composition.
30 to 150 parts by weight, preferably 40 to 140 parts by weight, of carbon black is added to 00 parts by weight.

If the amount of carbon black is less than 30 parts by weight, the reinforcing effect of the rubber composition is not sufficient.
If it exceeds 50 parts by weight, the dispersion in the rubber composition will be poor, the reinforcing effect will be reduced, the hardness will be further increased, and the grip properties will be poor. The nitrogen adsorption specific surface area of the carbon black (N ₂ SA) is in the range of 100m ² / g~300m ² / g. If it is less than 100 m ² / g, the reinforcing effect of the rubber composition is not sufficient, while if it exceeds 300 m ² / g, dispersion in the rubber becomes poor. Nitrogen adsorption specific surface area (N ₂ SA) is more preferably from 110m ² / g~150m ² / g. Examples of the type of carbon black used in the present invention include HAF, ISAF, and SAF.

In the present invention, 40% by weight or more of the total amount of carbon black in the rubber composition is previously mixed and dispersed in the emulsion-polymerized styrene-butadiene rubber. Then, when mixed with solution-polymerized styrene-butadiene rubber,
A rubber composition is obtained in which carbon black is unevenly dispersed in the emulsion-polymerized styrene-butadiene rubber.

By preliminarily mixing and dispersing carbon black in an emulsion-polymerized styrene-butadiene rubber having excellent abrasion resistance, the abrasion resistance is further improved in a state of being mixed with the rubber composition.

The rubber composition of the present invention may further contain an inorganic filler such as silica, clay, calcium carbonate, aluminum hydroxide, mica, etc., a silane coupling agent, sulfur, etc. which are commonly used in tire treads. Sulfurizing agents, various vulcanization accelerators, various tackifiers, various anti-aging agents, zinc oxide,
Fatty acids such as stearic acid can be added as long as the effects of the present invention are not impaired.

Next, the rubber composition of the present invention is produced, for example, by the following steps. (1) A predetermined amount of a softening agent is mixed and dispersed in each of the emulsion-polymerized styrene-butadiene rubber and the solution-polymerized styrene-butadiene rubber. In this case, the ratio of the softening agent to be mixed with the emulsion-polymerized styrene-butadiene rubber and the solution-polymerized-butadiene rubber may be the same or different. The softening agent mixed here is 30% by weight or more of the total amount of the softening agent mixed in the rubber composition.

(2) Carbon black is mixed and dispersed in the emulsion-polymerized styrene-butadiene rubber mixed with the softener. The carbon black mixed here is 40% of the total amount of carbon black mixed in the rubber composition.
% By weight or more.

(3) Solution-polymerized styrene-butadiene rubber adjusted in (1) above, emulsion-polymerized styrene-butadiene rubber adjusted in (2) above, remaining carbon black, softener, and other than sulfur and vulcanization accelerator Is mixed.

(4) Further, sulfur and a vulcanization accelerator are mixed in the rubber composition. The obtained rubber composition is molded into a tire, and is heated at a predetermined temperature for a predetermined time,
Vulcanize for 0 to 30 minutes.

[0022]

EXAMPLES Using the basic formulations shown in Table 1, the following compositions were used to prepare the rubber compositions of the examples.

A predetermined amount of a softening agent was mixed into each of the emulsion-polymerized styrene-butadiene rubber and the solution-polymerized styrene-butadiene rubber by a roll.

A predetermined amount of carbon black is added to the emulsion-polymerized styrene-butadiene rubber mixed with the above softener.
Mix with a 7 liter Banbury mixer.

A rubber component and a compounding agent other than the vulcanizing agent were mixed with a 1.7-liter Banbury mixer.

The rubber composition obtained above was mixed with sulfur and a vulcanization accelerator using a roll.

The above rubber composition was formed into a sheet and a tire, and vulcanized at 170 ° C. for 15 minutes.

The evaluation of the vulcanized rubber composition and the prototype tire was performed by the following method. (1) Lambourn abrasion test (wear resistance) The volume loss of each compound was calculated, and the loss amount of the reference comparative example in each evaluation was set to 100, and the loss was indicated by an index using the following formula. The larger the index, the better the wear resistance.

Wear index = value of reference standard for each evaluation / value of each formulation × 100 (2) Skid test (gripability) Skid resistance was measured using a Stanley portable skid tester. The measurement was performed at room temperature and the road surface was subjected to a safety walk. The numerical values were indicated by exponents using the following formula. The higher the index, the better the skid performance.

Skid index = numerical value of each formulation / standard value of each evaluation numerical value of comparative example × 100 (3) Evaluation with tires A 215 / 45R17 passenger car tire was prototyped, and a handling road (asphalt road surface) of about 1 km per lap. , And a feeling test of grip feeling and traction feeling was conducted. The evaluation was made according to a 10-point method. Comparative Example 1 serving as a criterion for each evaluation formulation was given 5 points. The higher the score, the better. In addition, the tire appearance after running a certain number of laps was scored and compared. The evaluation was performed according to the 10-point method, and the reference comparative example of each evaluation was set to 5 points. The higher the value, the better.

[0031]

[Table 1]

[0032]

[Table 2]

[0033]

[Table 3]

[0034]

[Table 4]

(1) Effect of the ratio of solution-polymerized styrene-butadiene rubber and emulsion-polymerized styrene-butadiene rubber According to Table 2, 90 to 6% of the solution-polymerized styrene-butadiene rubber were used.
It can be seen that the wear resistance and grip properties are excellent in the range of 0% by weight.

(2) Influence of uneven distribution of carbon black on emulsion-polymerized styrene-butadiene rubber From Table 3, Comparative Example 3 in which the uneven distribution of carbon black was 30 parts
Abrasion resistance and grip properties are improved in the case of Example 5 of 40 parts and in the case of Example 6 of 60 parts.

(3) Influence by the amount of aroma oil added afterwards From Table 4, the blend ratio is fixed, the amount of uneven distribution of carbon is also fixed to half, and the abrasion resistance is increased by increasing the amount of oil added first (decreasing the amount of oil added later). Improved grip (skid index, grip, and traction).

The embodiments disclosed this time are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

[0039]

As described above, according to the present invention, the rubber components are emulsion-polymerized styrene-butadiene rubber and solution-polymerized styrene-butadiene rubber, and a softening agent is preliminarily mixed with the rubber. Due to the mixing and dispersion, abrasion resistance and grip properties are simultaneously improved.

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Claims (2)

[Claims] 1. An emulsion-polymerized styrene-butadiene rubber 1
0 to 40% by weight, 100 parts by weight of a rubber component comprising 90 to 60% by weight of the solution-polymerized styrene-butadiene rubber, 20 to 180 parts by weight of a softener, and a nitrogen adsorption specific surface area (N
₂ SA) is a rubber composition containing 30 to 150 parts by weight of carbon black of 100 to 300 m ² / g; (1) 30% by weight or more of the total amount of the softener before mixing the carbon black (2) 40% by weight of the total compounding amount of the carbon black.
The above is a tread rubber composition for a high-performance tire, which is previously mixed and dispersed in the emulsion-polymerized styrene-butadiene rubber. 2. An emulsion-polymerized styrene-butadiene rubber 1
0 to 40% by weight, 100 parts by weight of a rubber component comprising 90 to 60% by weight of the solution-polymerized styrene-butadiene rubber,
20 to 180 parts by weight of a softener and a nitrogen adsorption specific surface area (N
₂ SA) is a method for producing a rubber composition containing 30 to 150 parts by weight of carbon black of 100 to 300 m ² / g, wherein (1) 30% by weight or more of the total blending amount of the softener is the emulsion polymerized styrene- Mixing a butadiene rubber and a rubber component of the solution-polymerized styrene-butadiene rubber, respectively; (2) 40% by weight of the total amount of the carbon black
Mixing and dispersing the above in an emulsion-polymerized styrene-butadiene rubber mixed with the softener, (3) mixing a compounding agent other than sulfur and a vulcanization accelerator with the rubber component, (4) adding sulfur and A method for producing a tread rubber composition for a high-performance tire, comprising a step of mixing a sulfur accelerator into the rubber composition obtained in the step (3).