A rust-proof coating or Automotive Rustproof Paint is the one that does not contain a hazardous metal such as chromium and is able to form a thin coating in which crack generation is inhibited even after a baking treatment at a high temperature, considering all the whole composition, usually 10 to 40% by weight of an organic silicon compound, 0.05 to 5.0% by weight of an organic Ti, 20 to 60% by weight of one or more powder selected from the group of zinc powder, zinc alloy powder, and aluminum powder, and 10 to 60% by weight of an organic solvent.
A coating having excellent anti-corrosive properties can be formed by coating the above-mentioned paint composition preceding by heating at a temperature of from 200 to 400 degrees C.
The present invention relates to a rust-proof paint mixture which does not contain a hazardous metal such as chromium, and a method of fabrication a member having a rust-proof coating using the rust-proof paint composition. More broadly, the present invention relates to a rust-proof paint mixture which can form an covering having fabulous anti corrosive attributes and the coating is thin enough to be applied to a steel plate for press casting used for.
An Automotive Rustproof Paint mainly containing a zinc powder and chromatic acid had been much used as a paint to control corrosion of a member having metallic properties like that of steel.
This paint has ace retention stability because the paint can keep the zinc powder stable for a long period and because of a passivization effect that hexavalent chromium provides.
Besides, a layer formed from a paint having a zinc powder forbids corrosion of a metal substrate such as steel because of the known effect of zinc of providing sacrificial covering. Therefore, the coating exhibits superior rust-proof properties.
Notwithstanding, there has lately been concern of environmental pollution and health damage to the human body caused by the toxicity of hexavalent chromium, and a movement to impose legal limitation on hazardous metals has came into effect.In accordance with this movement, many industries consider not using hazardous metals such as hexavalent chromium at all. Hence, in the field of rust-proof paints, there is a strong desire to set up a paint totally free from dangerous metals such as chromium.
Such rust-proof paints which do not include chromium are made up of zinc powder and a binder component dispersed or dissolved in a solvent. The binder component of zinc-rich paints can be classified into an organic type or an inorganic type. Because an inorganic component is much superior from the viewpoint of durability, a zinc-rich Automotive Rustproof Paint having an inorganic binder element is used for an undercoating agent in heavy-duty coatings.
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