Rubber composition for adhering steel cord
A rubber composition for adhering a steel cord that improves wet heat-resistant adhesioness, particularly heat-resistant adhesioness, by preventing adhesion deterioration due to heat, as well as initial adhesioness between a steel cord and a rubber, is disclosed. The rubber composition comprising 100 parts by weight of a diene rubber component and from 0.1 to 30 parts by weight of composite graphite particles containing boron, obtained by heating and graphitizing carbon black together with boron or a compound containing boron.
1. A method for producing a rubber-steel cord composite comprising:
heating and graphitizing carbon black together with boron or a compound containing boron thereby to obtain composite graphite particles comprising a graphite structure and a carbide of boron formed on the surface of the graphite structure,
mixing 100 parts by weight of a diene rubber component and from 0.1 to 30 parts by weight of the composite graphite particles thereby to prepare a rubber composition, and
covering a steel cord with the rubber composition thereby to obtain the rubber-steel cord composite.
2. The method as claimed in claim 1 , wherein the steel cord has brass plated thereon, and the rubber composition is applied to the steel cord.
3. The method as claimed in claim 1 , wherein the heating is conducted at a temperature of 1500° C. or higher.
4. The method as claimed in claim 1 , wherein the heating is conducted by induction heating the carbon black and the boron or the compound containing boron in an induction furnace.
5. The method as claimed in claim 1 , wherein the carbon black has an average particle diameter of 500 nm or less.
6. The method as claimed in claim 1 , wherein a molar ratio of the carbide of boron (B 4 C) constituting the composite graphite particles to the total carbon atoms in the composite graphite particles excluding carbon atoms contained in the carbide is from 1:5 to 1:500.
7. The method as claimed in claim 1 , wherein an organic acid cobalt salt is further compounded in a proportion of from 0.1 to 0.3 parts by weight, in terms of a cobalt metal content, per 100 parts by weight of the diene rubber component.
8. The method as claimed in claim 1 , wherein a resorcin or a resorcin derivative is further compounded in a proportion of from 0.5 to 5 parts by weight per 100 parts by weight of the diene rubber component, and hexamethylene tetramine or a melamine derivative is further compounded in an amount of 0.5 to 2 times the weight part of the resorcin or resorcin derivative.