JPH07102121A - Rubber composition - Google Patents

Abstract

PURPOSE:To obtain a rubber composition, good in adhesion to steel and useful as tires, etc., by blending a raw material rubber with butadiene rubber having 1,2-vinyl bond and terminals modified with maleic anhydride, a specific melamine derivativc a cresol resin and sulfur. CONSTITUTION:This rubber composition is obtained by blending (A) 100 pts.wt.. raw material rubber (e.g. natural rubber) with (B) 1-10 pts.wt. butadiene rubber having >=60% 1,2-vinyl bond content and terminals modified with maleic anhydride, (C) 1-5 pts.wt. partial condensate of hexamethylolmelamine pentamethyl ether expressed by the formula (n is 1-3), etc., (D) 0.5-5 pts.wt. m-cresol resin and (E) 4-7 pts.wt. sulfur and further, as necessary, suitably blending a blending agent such as carbon black or a vulcanization accelerator therewith. The rubber composition has good adhesion not only to steel cords plated with brass but also steel cords unplated with the brass and is useful as steel belt tires, etc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber composition having excellent adhesion to steel cord.

[0002]

2. Description of the Related Art Conventionally, steel cords have been applied to various uses. For example, as the demands for automobile tires have become higher, steel belt tires (tires made of steel cord whose belt layer is coated with coat rubber). Has been used more and more. Steel belt tires are advantageous for handling and stability of automobiles, wear resistance of tires, etc., but steel cords are used as a reinforcing material, and the adhesiveness between the steel cords and the coated rubber is important for product quality. Affect. Therefore, in order to obtain good adhesion between the steel cord and the coated rubber, the surface of the steel cord is usually plated with brass.

However, since the cut end surface of the steel cord is not plated with brass and the steel material forming the steel cord is exposed, in the steel belt tire, the steel cord is formed at the widthwise end portion of the belt layer. There was a problem of separation in which the cut end and the coated rubber were separated.

[0004]

SUMMARY OF THE INVENTION The present invention provides adhesiveness to steel cords having good adhesiveness not only to brass-plated steel cords but also to brass-plated steel cords. An object is to provide an excellent rubber composition.

[0005]

The rubber composition of the present invention comprises:
60% of 1,2-vinyl bond amount to 100 parts by weight of raw rubber
1 to 10 parts by weight of butadiene rubber end-modified with maleic anhydride and 1 to 5 parts by weight of a partial condensate of hexamethylol melamine pentamethyl ether,
0.5 to 5 parts by weight of meta-cresol resin and 4 to 7 of sulfur
It is characterized by being mixed in parts by weight.

As described above, according to the present invention, the raw material rubber is blended with the specific polybutadiene rubber, the partial condensate of hexamethylol melamine pentamethyl ether, the meta-cresol resin, and the sulfur. It becomes possible to improve the adhesiveness. Hereinafter, the configuration of the present invention will be described in detail.

Raw rubber. Although not particularly limited, for example, natural rubber (N
R) alone or natural rubber (NR) and synthetic isoprene rubber
(IR), butadiene rubber (BR), styrene-butadiene rubber (SBR), ethylene-propylene rubber (EP
M, EPR) and butyl rubber (IIR) are blended.

A butadiene rubber having a 1,2-vinyl bond content of 60% or more, preferably 70% or more and end-modified with maleic anhydride. Examples of this butadiene rubber include Advance of the US
RICOBOND 1756 from d Resins, Inc. may be mentioned. In addition,
This butadiene rubber has a weight average molecular weight of 5000 to 1
It is preferably 0,000.

If the 1,2-vinyl bond content is less than 60%, the effect of improving the adhesiveness to steel cords not plated with brass will be lost. Further, when the terminal is not modified with maleic anhydride, the processability during kneading remarkably deteriorates. The amount of butadiene rubber used is 1 to 10 parts by weight based on 100 parts by weight of the raw material rubber. If it is less than 1 part by weight, the effect of improving the adhesion with the steel cord is lost. Further, if it exceeds 10 parts by weight, the 100% modulus is largely decreased, the separation property between the belt layers is apt to be deteriorated, and the effect of improving the adhesiveness with the steel cord is almost eliminated.

Partial condensate of hexamethylol melamine pentamethyl ether. The partial condensation product of hexamethylol melamine pentamethyl ether is a compound having the following formula.

[0011]

As the partial condensate of hexamethylolmelamine pentamethyl ether, general commercial products can be used. For example, Sumikanol 507 manufactured by Sumitomo Chemical Co., Ltd.
(Contains 50% of hexamethylol melamine pentamethyl ether partial condensate). The object of the present invention cannot be achieved even if other polymethoxymethylmelamine, for example, hexamethoxymethylmelamine is used.

The amount of the partial condensate of hexamethylolmelamine pentamethyl ether used is 1 to 5 parts by weight based on 100 parts by weight of the raw rubber. If it is less than 1 part by weight, the effect of improving the hardness of the obtained rubber composition becomes insufficient, while if it exceeds 5 parts by weight, the breaking property is deteriorated. Metacresol resin.

A general commercial product may be used. The amount used is 0.5 to 5 parts by weight with respect to 100 parts by weight of the raw rubber. 0.
If it is less than 5 parts by weight, the effect of improving the hardness of the obtained rubber composition is small. If it exceeds 5 parts by weight, the breaking property is deteriorated and the exothermic property after vulcanization is increased, which is not preferable. Sulfur.

The amount of sulfur used is 4 to 7 parts by weight based on 100 parts by weight of the raw material rubber. This is because if it is less than 4 parts by weight, the effect of addition is small, and if it exceeds 7 parts by weight, sulfur blooms on the surface of the unvulcanized rubber composition obtained, which becomes an obstacle in processing. The rubber composition of the present invention is obtained by blending these raw rubbers with these butadiene rubber, a partial condensate of hexamethylol melamine pentamethyl ether, a meta-cresol resin, and sulfur, but if necessary. Other compounding agents such as carbon black and vulcanization accelerator may be appropriately compounded.

[0016]

[Examples] Rubber compositions having the compounding contents (parts by weight) shown in Table 1
(Comparative Examples 1 to 4 and Examples 1 to 6) were produced. For these samples, 100% modulus, tensile strength and elongation at break are JIS
Dumbbell No. 3 was punched out and measured according to JIS-K-6301, and hardness was measured according to JIS A. The results are shown in Table 1.

For these samples, A
STM adhesion evaluation was performed. The results are shown in Table 1. ASTM Adhesion Evaluation : (1) Adhesion of brass-plated steel cords Brass-plated steel cords arranged in parallel at 12.5 mm intervals (1
(* 5 structure) is coated with rubber composition from both sides and embedded, and a fabric with a width of 25 mm is vulcanized at 170 ° C for 20 minutes to make a test sample, and the wire is pulled out in accordance with ASTM D 2229. The coating rate (%) was evaluated. The larger the number, the better the adhesion. (2) Adhesion of steel cord without brass plating The method is the same as in (1) above, but the steel cord is not brass-plated.

[0018] As is clear from Table 1, the rubber compositions of the present invention (Examples 1 to 6) have excellent adhesion to steel cords regardless of the presence or absence of brass plating.

[0019]

As described above, according to the present invention, hexamethylolmelamine, a butadiene rubber having a 1,2-vinyl bond content of 60% or more and a terminal modified with maleic anhydride, based on the raw rubber Partial condensate of pentamethyl ether, meta-cresol resin, and sulfur are added in specific amounts to improve adhesion not only to brass-plated steel cords but also to brass-plated steel cords. Can be made. Therefore, when the steel cord is coated with the rubber composition of the present invention to form the belt layer of the tire, it becomes possible to prevent the separation of the end portion of the belt layer. The rubber composition of the present invention can be applied not only to the belt layer of a tire but also to other uses such as a conveyor belt.

Continuation of front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display area C08L 61:18)

Claims (1)

[Claims] 1. 1 to 10 parts by weight of a butadiene rubber having a 1,2-vinyl bond content of 60% or more and end-modified with maleic anhydride, and hexamethylol melamine pentamethyl based on 100 parts by weight of a raw rubber. 1 to 5 parts by weight of partial condensate of ether, 0.5 to 5 parts by weight of meta-cresol resin,
A rubber composition containing 4 to 7 parts by weight of sulfur.