JPS581734A - Rubber composition for tire cap tread - Google Patents

Abstract

PURPOSE:To provide the titled compsn. which has excellent skid characteristics and wear resistance and does not deteriorate blowout resistance, by adding specified coarbon black to a raw rubber such as styrene/butadiene copolymer rubber. CONSTITUTION:90-300pts.wt. carbon black having an iodine adsorption of 160- 200mg/g, a DBP oil absorption of 110-140ml/100g and tinting strength of tint value of 120-150 (Tint: No.ASTM-D-3265) is blended with 100pts.wt. raw rubber selected from a styrene/butadiene copolymer rubber having a styrene content of 30wt% or higher, butyl rubber, a halogenated butyl rubber or a mixture thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rubber composition for tire cap tread,
Specifically, by adding a specific amount or more of a specific carbon gracza, a tire cap, f, which has superior skid/grid properties and abrasion resistance and does not impair blowout resistance compared to conventional rubber compositions for cap treads. The present invention relates to a rubber composition for a tread.

Conventionally, butyl rubber (I
IR), or a styrene-butanoene copolymer comb (SBR) with a high styrene content, and a rubber composition containing SAF' curd, which has a relatively high iodine adsorption amount and DBP oil absorption amount, as carbon black. Alternatively, various types of resins are further added to the rubber composition, or an increased amount of aromatic oil is added, but in any of these rubber compositions, the wear resistance after vulcanization is is decreasing.

For this reason, when these rubber compositions are used for the cap tread of competition tires, the cap tread must be made thicker to prevent wear, and if the rubber composition is made too thick, it has the disadvantage of blowing out due to heat generated during driving. there were. In addition, if the darts are made to have a normal thickness instead of being made thicker, the abrasion resistance will be lower than that of conventional rubber, and the volume of the cano-no-trend part will decrease significantly in the latter half of the competition, so the hysteresis loss of the whole cano-no-tresode part will decrease. However, if the wear is significant, the tire may wear out completely during the competition, forcing the tire to be replaced.

As described above, a rubber composition that has both skid properties and abrasion resistance as a canozo tire for competition tires that require severe running conditions such as races and rallies has not yet been obtained.

The present invention has been made from this viewpoint, and aims to provide a rubber composition for tire carab treads that has excellent skid properties and abrasion resistance after vulcanization and does not impair blowout resistance. It is suitably used for cap treads of tires for competitions such as races and rallies that require demanding driving conditions.

The present inventors achieved the above object by incorporating a specific amount or more of a specific carbine black into a comb composition.

That is, the present invention provides raw material rubber 10 consisting of a styrene-butanoene copolymer rubber having a styrene content of 30% by weight or more, butyl rubber, and a mixture of two or more of halodanated butyl rubber.
The amount of iodine adsorbed is 160 to 200.0 parts by weight. n9/
g, DBP e, oilspot 110-140ml/100. !
This is a rubber composition for tire cars and tire tires, characterized in that it contains 90 parts by weight or more of a carbon resin having a tint value of 120 to 150 and a tinting strength of 120 to 150.

The raw material rubber used in the rubber composition of the present invention includes SBR, IIR, and chlorinated or brominated rubber having a styrene content of 30% by weight or more, which is used as the cap tread of ordinary competition tires. Octanobutyl rubber (H
at-IIR) alone or in a mixture of two or more thereof.

Also, the car used? The properties of Numbura are iodine adsorption of 160 to 200 da/g and DBP oil absorption of 110 to 140.
ml/100J? And the tinting power is Tint value (Tin
t AASTM D 3265) from 120 to 15
It must be in the range of 0. Carbine black in this range has a high reinforcing property, and moreover, it has a higher reinforcing property than SAF carden black, which is used in rubber compositions for tire cap treads of conventional competition tires.
Since carbine black in this range is used for the cap tread of a tire, the tire adapts well to the unevenness of the road surface, resulting in good skid and slip characteristics. If the properties of the carpin bra are outside this range, the vulcanization properties of the comb composition, particularly skid properties, abrasion resistance, blowout resistance, etc., will not reach the desired level, which is undesirable.

The amount of carbon black used in the present invention must be 90 parts by weight or more based on 100 parts by weight of the raw material comb. The higher the amount of carbine black, the better the case. Therefore, there is no particular upper limit set, but if the amount is too large, it becomes impossible to knead with the raw rubber, so the upper limit is the limit that can be mixed with the rubber. According to the inventors' confirmation, this upper limit is 3 parts per 100 parts by weight of rubber.
It is possible to knead up to 0.00 parts by weight. If the blending amount of carbon black is less than 90 parts by weight, the reinforcing properties will be low and the slip and slip properties will be poor, making it undesirable for use as a tire cap tread for competition tires. Also, this car pin pla,
It is also possible to combine it with an extender oil and use it as a so-called veneer, tocarbin plastic, or a master.

In addition, in the present invention, compounding agents that are blended in ordinary canozotolenod rubber, such as acetic acid, stearin, various anti-aging agents, wax, extender oil, vulcanization accelerator, and sulfur are appropriately blended. Ru.

In particular, the rubber composition of the present invention is required to be compounded into tires for competition use.

The present invention will be specifically described below based on Examples and Comparative Examples. Note that all compounding values in Table 2 are parts by weight.

Example 1 and Comparative Examples 1 to 4 The raw rubber shown in Table 2, the vulcanization accelerator, and the compounding ingredients excluding sulfur were kneaded for 6 minutes in a 1,81-Mann Guri mixer, and then the vulcanization accelerator and sulfur were mixed. The mixture was blended and kneaded for 4 minutes using an 8-inch roll to obtain a rubber composition. The properties of the carbon black in this rubber composition are shown in Table 1.

This rubber vulcanization was vulcanized at 160'C for 20 minutes, and the properties of the vulcanized product were evaluated. The results are shown in Table 1.

Note that the characteristics of the vulcanizate were evaluated by the following method.

Tensile strength, elongation, and 300% tensile stress are JIS K2CO
2, and the skid and do characteristics were measured in an atmosphere of 70'C using a Pretty Portable Ski and Tochistor, and a 3M Safety Walk as the road surface. Abrasion resistance was measured using a Pico abrasion tester in an atmosphere of 70C with a load of 15 kg, and blowout resistance was measured using a Gutdrich flexmeter with a load of 15 kg.
The time required for blowout to occur in an atmosphere of 100°C was measured at a stroke of 5.71 mm and a vibration frequency of 1.80 Orpm. For these skid characteristics, abrasion resistance, and blowout resistance, the value of Comparative Example 1 was expressed as 100 and expressed as an index.

Comparative Example 1 in Table 1 is an example of a rubber composition for carab tread for competition tires, and the comb composition of Comparative Example 2 is
This is a comb composition in which the amount of aromatic extender oil is further increased. Furthermore, the rubber composition of Comparative Example 3 is the same as the rubber composition of Comparative Example 1, with an increased amount of vulcanization accelerator (CM) and a reduced amount of sulfur. This is a composition containing a chill-phenol copolymer resin.

Furthermore, the rubber composition of Comparative Example 5 was made from SBR (styrene content: 35% by weight), which is the raw material rubber for the comb composition of Comparative Example 1.
A part of the material was replaced with SBR having a higher styrene content (styrene content: 60% by weight).

The rubber compositions of Comparative Examples 2 to 5 were obtained by changing the formulation of the rubber composition of Comparative Example 1 to improve skid properties as described above, and although the skid properties were improved somewhat, the abrasion resistance and blow resistance were A marked decrease in out-of-field performance and low wear resistance are particularly undesirable in competition tires because they lead to a decrease in skid performance in the latter half of competition.

The rubber composition of Example 1 contained I 2 'We, instead of carbon black (SAF) in the comb composition of Comparative Example 1.
N'1itzDBPCars with high oil absorption are those that use rubber, but they have excellent skid and wear properties and wear resistance, and do not impair strength or blowout resistance.

As explained above, tires containing the comb composition of the present invention have advantages such as excellent skid/grip properties and wear resistance, and also do not impair blowout resistance. Suitable for use as notore and de.

Patent applicant: Yokohama Com Co., Ltd. Agent Patent Attorney Tetsuya Ito

Claims (1)

[Claims] The amount of iodine adsorbed is 160 to 200 parts per 100 parts by weight of a raw material comb consisting of styrene-butadiene copolymer rubber, butyl rubber, and a mixture of two or more of styrene-butadiene copolymer rubber with a styrene content of 30 parts by weight or more.
11. A rubber composition for a tire cap tread, characterized in that it contains 90 parts by weight or more of carbon graccharide having a DBP oil absorption of 110 to 140 ml/100 g and a tint value of 120 to 150.