Elongated steel element comprising a ternary or quaternary brass alloy coating and corresponding method

Abstract

An elongated steel element adapted for the reinforcement of rubber products is covered with a ternary or quaternary alloy coating of copper-M-zinc. M is one or two metals selected from the group consisting of cobalt, nickel, tin, indium, manganese, iron, bismuth and molybdenum. The copper content inside the coating ranges from 58 weight percent to 75 weight percent, the content of said one or two metals inside the coating ranges from 0.5 weight percent to 10 weight percent, the remainder is zinc and unavoidable impurities. The one or two metals are present throughout the coating. The phosphorus is present on and / or in the coating in an amount ranging from 0.3 milligram per square meter to 1 milligram per square meter of the coating. The coating further lacks triazole residues. Good results for under cure adhesion have been obtained. Furthermore, a corresponding method for manufacturing such an elongated steel element is disclosed.

Description

TECHNICAL FIELD[0001]The present invention relates to an elongated steel element adapted for the reinforcement of rubber products. The present invention also relates to a process for manufacturing such an elongated steel element.BACKGROUND ART[0002]Elongated steel elements such as brass coated steel wires and steel cords are widely used to reinforce rubber products such as tires. In order to have a good adhesion formation and to reduce the rate of degradation of adhesion, particularly due to ageing in hot humid conditions, cobalt complexes are added to the rubber compound. However, cobalt is considered to be a poison for the rubber since, like most transition metals, it is an oxidation catalyst. As a result, oxidation of diene rubber molecules will be accelerated due to the presence of cobalt, which leads to earlier rubber ageing.[0003]Moreover, cobalt also speeds up crack growth rate of the rubber. In addition to the above disadvantage there is also the following problem: Cobalt is...

AI Technical Summary

Benefits of technology

The patent text explains that small amounts of phosphorus on a rubber coating, along with the absence of triazole residues, improve adhesion when the rubber is vulcanized for half of the regular curing time. It also states that amounts of phosphorus above 1 mg / m2 have lower adhesion performance in under cure. The technical effect of the patent text is that it explains how to improve rubber adhesion during vulcanization.

Problems solved by technology

As a result, oxidation of diene rubber molecules will be accelerated due to the presence of cobalt, which leads to earlier rubber ageing.

Moreover, cobalt also speeds up crack growth rate of the rubber.

In addition to the above disadvantage there is also the following problem: Cobalt is a strategic material and it is quite expensive.

By adding cobalt to the whole rubber compound, one adds too much cobalt since it has only a positive function at the brass surface.

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