Surface sulfurization of a metal body by flame spray pyrolysis

Abstract

Process for surface sulfurization of a body, especially a metal reinforcement, at least the surface of which comprises a layer of a metal, called the surface metal, able to form sulphides, this metal for example being chosen from copper, zinc and their alloys; this process comprises at least one step of flame spray pyrolysis (FSP) of a sulphur-donating precursor, for example thiophene, generating hydrogen sulphide in the flame. The bodies or metal reinforcements thus treated may be directly bonded, without a bonding primer or addition of a metal salt such as a cobalt salt, to matrices of unsaturated rubbers such as natural rubber.

Description

technical field [0001] The present invention relates to a method for the surface treatment of metals, in particular metal bodies, which can be used as reinforcements in metal / rubber composites intended in particular for the manufacture of Articles made of rubber, such as tires. [0002] More specifically, the invention relates to a method for the surface vulcanization of these metals, the purpose of which is to make possible the subsequent adhesion of these metals to ethylenically unsaturated polymers, such as natural rubber. Background technique [0003] Metal / rubber type composites are known, in particular metal / rubber type composites for tires. The composite usually consists of a matrix made of unsaturated rubber, usually diene rubber, which includes metallic reinforcing elements (or "reinforcements"), such as wires or cords made of carbon steel, the Diene rubbers can be crosslinked with sulfur. [0004] Due to the fact that composite materials are subjected to very hi...

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Problems solved by technology

[0008] However, it is also known that the presence of these cobalt compounds in rubber compositions makes rubber compositions more sensitive to oxidation and aging, so that due to the various stresses encountered (in particular mechanical and / or thermal stresses) , the formation of sulfides changes gradually so that the bond between the carbon steel and the rubber matrix also tends to weaken over time, which may be accelerated by the presence of moisture in addition to the aforementioned degradation process

[0009] The incorporation of cobalt also adds significantly to the cost of the rubber composition, not to mention that due to recent developments in European regulations, cobalt and cobalt salts are considered relatively toxic to the environment, so the removal of cobalt from these compositions is in the long run desired

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