Initial solids mixture for a later organic coating application

Abstract

An initial solids mixture for a later organic coating, such as pigmented coatings, films, priming coats, etc., e.g., for a coil coating method in which an initial solids mixture is applied to a substrate, e.g., broad strip, and this is thereby pre-coated, wherein the initial solids mixture includes, as additive particles, boron carbide and / or silicon carbide and / or compounds of transition elements or lanthanides, the electrical conductivity of which is selected to be in the metallic range (σ>102 1 / Ωcm and σ<107 1 / Ωcm), during the later coating, the additive particles have a continuous physical connection in at least one spatial direction.

Description

FIELD OF THE INVENTION [0001] The present invention relates to an initial solids mixture for a later organic coating application. BACKGROUND INFORMATION [0002] German Published Patent Application No. 197 48 764 describes an initial quantity for producing weldable organic coil coatings. Beside the normal organic components, which later form the matrix of the coating by curing and / or mutual cross-linking, the initial solids mixture has, as additive pigments in quantities between 40 and 70% zinc and / or aluminum and / or graphite and / or molybdenum disulfide and / or soot and / or iron phosphide. The additive pigments are used at least partially for the improvement or implementation, as the case may be, of an electrical conductivity of the initial solid mixture, with which a coil coating method first becomes possible. [0003] In this method, used particularly in the metal working industry, the initial solid mixture is deposited onto a substrate, e.g., broad strip, and cured, whereby the latter ...

AI Technical Summary

Benefits of technology

The present invention provides an initial solids mixture that includes an additive pigment and additive particles. The additive particles are toxicologically less risky and have better electrical conductivity properties compared to the conventional phosphides. The non-noble metallic conductors may have a negative influence on the conductivity of the coating, but this can be avoided by using highly conductive compounds. The adhesive agent used in the coating can also have an intrinsic electrical conductivity, which further improves the corrosion protection and weldability of the coating. The particle size of the additive particles should be as high as possible to ensure better percolation and higher electrical conductivity. The weight ratio of the adhesive agent to the conductivity additive particles should also shift in favor of the adhesive agent to improve the overall performance of the coating.

Problems solved by technology

However, in the case of an initial solids mixture, the addition of iron phosphide carries with it the danger of phosphane (PH3) development, in the case of hydrolysis and combustion, which does not have an inconsiderable toxicity, and also that iron phosphide has a not inconsiderable cost price.

Furthermore, in the case of environmentally friendly water being used as solvent, the risk of hydrolysis always exists.

Depending on the degree of oxide formation, this leads to a decrease in conductivity and to undefined variations in conductivity, and thus to diminished process safety during welding.

A negative influence comparable to the oxide formation in the case of the less noble metallic conductors, which leads to high contact resistances and hard to control conductance fluctuations, may not be observed in the case of the electrically conducting compounds.

Percolation then occurs earlier, while settling of additive particles at equal particle size may set in with delay.

The conventional coating solutions for coil coating applications probably work only in adhesive agent systems which can hardly be developed aqueously.