KR20030020147A - Rubber Composition of Undertread with Incresed Heat Transfer for Tire - Google Patents

Abstract

PURPOSE: Provided is a rubber composition for under-tread, which has improved heat conductivity and can shorten the vulcanizing time, therefore can prevent the performance deterioration caused by the property deterioration of tread rubber and improve productivity. CONSTITUTION: The rubber composition for under-tread contains a natural rubber or a synthetic rubber of a natural rubber and a butadiene rubber, as a raw rubber, and additives such as a processing aid, zinc oxide, stearic acid, a processing oil, and 5-40pts.wt.(based on the raw rubber) of an acetylene black and 20-50pts.wt. of a carbon black which is N351 or N550.

Description

Rubber composition of Undertread with Incresed Heat Transfer for Tire with improved thermal conductivity

The present invention relates to a rubber composition for undertreads, and more particularly to a rubber composition for undertreads in which a predetermined amount of acetylene black is added to improve the thermal conductivity of the tread rubber.

In the tire manufacturing process, the vulcanization process vulcanizes rubber through an external temperature source that is transferred through a mold and an internal source through a heat source such as steam, hot water or nitrogen gas into the tire.

In the tire industry, it is very important to increase the productivity by shortening the vulcanization time of the tire and to secure the quality by securing the appropriate vulcanization time. By increasing the temperature supplied to the inside or outside of the tire, the vulcanization time can be shortened.However, when supplying the internal heat source or the external heat source above the proper temperature, the rubber and cords of the tire tread part and the belt part are deteriorated to improve the quality. Is degraded.

The last point of vulcanization at the time of vulcanization of the tire is the rubber of the belt layer inside the tire. This is because heat supplied from the outer side (mold) touches the rubber of the belt layer via the tread, and heat supplied from the inner side also reaches the belt layer through the inner-carcass.

When the temperature of the belt layer of the tire rises, the interfacial adhesion between the steel cord / rubber decreases, which can cause a deterioration in quality.

Therefore, there is a need for development of a tire under-trad rubber composition that can deliver the heat source supplied through the mold to the belt rubber in the inner side while preventing degradation of physical properties and quality of the tire.

The present inventors have completed the present invention by finding out that the solution of the problems associated with the conventional vulcanization process can be shortened by introducing acetylene black, which is excellent in thermal conductivity, into the under rubber of the tire. .

It is an object of the present invention to provide an undertread rubber composition which prevents a performance drop due to a drop in properties of the tread rubber and shortens the finished product vulcanization time to improve productivity.

The present invention provides a tire tread rubber composition comprising natural rubber alone or synthetic rubber of natural rubber and butadiene rubber as a raw material rubber, and including conventional additives such as process aids, zinc oxide, stearic acid and process oil. The rubber composition includes 5 to 40 parts by weight of acetylene black relative to the raw material rubber, and 20 to 50 parts by weight of carbon black.

Acetylene black is introduced to increase the thermal conductivity of rubber. Compared to the conventional tread rubber, which has only been applied to carbon black, acetylene black is used to reduce the time that the belt layer inside the tire reaches a certain temperature. give.

Acetylene black usable in the present invention is not particularly limited as long as it is excellent in thermal conductivity. Typically, acetylene black can be prepared by continuously pyrolyzing acetylene gas, and preferably, the acetylene black forms a three-dimensional chain structure with colloidal particles and uses less impurities. The acetylene black is very excellent in thermal conductivity when applied to rubber, compared to the furnace (furnace) black such as commonly used N220, N375 and the like.

In a preferred embodiment of the present invention in the form of granules of acetylene black satisfying the above conditions, in the total weight of moisture in the range of 0.10 to 0.30%, ASH 0.01 to 0.10%, GRIT 0.0001 to 0.05%, and physical and electrical properties The resistance is 0.200 ~ 0.300Ω / cm, the iodine adsorption value is 95 ~ 120mg / g, the acetone extraction is within 0.0005 ~ 0.005%, and the apparent density is selected within 0.10 ~ 0.35g / cc and introduced into the rubber composition. The shortening effect of was observed.

The amount of the acetylene black added in the rubber composition may vary slightly depending on the characteristics of the acetylene black to be specifically applied, but is usually in the range of 5 to 40 parts by weight. If acetylene black is added less than 5 parts by weight, the thermal conductivity is insignificant, and the difference does not appear clearly when compared with carbon black alone. When it exceeds 40 parts by weight, acetylene black is not dispersed well and the heat of rubber is not generated. It is not preferable because there is a possibility that it may increase and decrease physical properties.

The carbon black added to the rubber composition together with the acetylene black does not require any particular limitation, but experimentally, various types of carbon black are used. N351 or N550 is excellent in terms of the effect of the present invention. It is more preferable. The carbon black is 20 to 50 parts by weight compared to the raw material rubber, if less than 20 parts by weight of the thermal conductivity of the under-tread rubber is reduced, if the excess exceeds 50 parts by weight of the rubber heat increase unsuitably as an under-tread rubber It is not desirable.

Other components added to the undertread rubber composition of the present invention include, for example, raw rubber, zinc oxide, stearic acid, process oil, and the like, as known additives, which are sufficient to be appropriately selected and carried out according to a range of known amounts. Description is omitted.

Hereinafter, the contents of the present invention will be described in detail through examples. However, the following examples are intended to illustrate the present invention in more detail, and the scope of the present invention is not intended to be limited thereto.

Comparative Example

100 parts by weight of natural rubber as a raw material rubber as shown in Table 1, excluding acetylene black, 45 parts by weight of N351, 5 parts by weight of zinc oxide, 2 parts by weight of stearic acid, 5 parts by weight of A # 2, 2.5 parts by weight of vulcanizing agent 0.7 parts by weight of accelerator was added to the Banbury mixer and discharged at a temperature of 160 ° C.

<Example 1>

100 parts by weight of natural rubber as a raw material rubber as shown in Table 1, 38 parts by weight of N351, 5 parts by weight of acetylene black, 5 parts by weight of zinc oxide, 2 parts by weight of stearic acid, 5 parts by weight of A # 2, 2.5 parts of vulcanizing agent 0.7 parts by weight of accelerator was added to the Banbury mixer and discharged at a temperature of 160 ° C.

Based on the comparative example, the thermal conductivity increase rate and the effect of shortening the vulcanization time through proper vulcanization of the belt rubber when applying a specific specification of a tire are shown in Table 2.

<Example 2>

It was prepared in the same manner as in Example 1 except adding 25 parts by weight of N351 and 17 parts by weight of acetylene black.

<Example 3>

It was prepared in the same manner as in Example 1 except adding 15 parts by weight of N351 and 25 parts by weight of acetylene black.

<Example 4>

Except for adding N 351 35 parts by weight of N550, 20 parts by weight of acetylene black was prepared in the same manner as in Example 1.

Example 5

A mixed rubber of 60 parts by weight of natural rubber and 40 parts by weight of butadiene rubber was prepared as in Example 1, except that 25 parts by weight of N351 and 30 parts by weight of acetylene black were added.

<Table 1> Mixing ratio of tread rubber

Composition Comparative example Example 1 Example 2 Example 3 Example 4 Example 5 Natural rubber 100 100 100 100 100 60 butadiene 0 0 0 0 0 40 N351 45 38 25 15 0 25 N550 0 0 0 0 35 0 Acetylene black 0 5 17 25 20 30 Zinc oxide 5 5 5 5 5 5 Stearic acid 2 2 2 2 2 2 A # 2 5 5 5 5 5 5 Vulcanizing agent 2.5 2.5 2.5 2.5 2.5 2.5 accelerant 0.7 0.7 0.7 0.7 0.7 0.7

<Table 2> Thermal conductivity increase and shortening time

Item Comparative example Example 1 Example 2 Example 3 Example 4 Example 5 Thermal conductivity increase rate (%) 100 106 127 151 158 169 Belt rubber 145 ℃ reach time standard -0.4 minutes -0.9 minutes -1.3 minutes -1.8 minutes -2.3 minutes

According to the present invention, it is possible to shorten the time for the belt layer to reach a specific temperature, thereby preventing the vulcanization of the tread rubber while reducing the vulcanization time, preventing the performance deterioration due to the deterioration of the properties of the tread rubber, and the finished product vulcanization time. It is effective to shorten the productivity.

Claims (2)

In the rubber composition for tire treads comprising natural rubber alone or synthetic rubber of natural rubber and butadiene rubber as a raw material rubber, and including conventional additives such as process aids, zinc oxide, stearic acid, process oil, etc. A rubber composition for under treads, comprising 5 to 40 parts by weight of acetylene black and 20 to 50 parts by weight of carbon black relative to the raw material rubber. According to claim 1, wherein the carbon black is rubber composition for under-tread, characterized in that N351 or N550.