US 3,971,708 AGranted

Electrocoating process

AssigneeSCM Corporation

InventorsGerald G. Davis, Joan M. Keough

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Abstract

Advantageously controlled paint film flow during curing of the film at elevated temperature for avoidance of inadequately coated areas is obtained in an electrocoating operation of an electrode workpiece employing as paint vehicle a mixture of electrodepositable resin and water-dispersible aminoplast or phenoplast resin crosslinkable therewith by incorporating into said vehicle, or into the bath containing same, a small proportion of curing accelerator acid such as a sulfonic acid which is codepositable with said paint film in concentration sufficient for yielding a substantially continuous cured film on the resulting coated substrate. The degree of cure of the deposited coating is monitored by monitoring a property of cured coating which is a function of the degree of cure, and the concentration of the curing accelerator in the bath is adjusted in response thereto to maintain the monitored property at a predetermined value.

Claims12

Dependent claims

In a continuous process for coating continuous electrode stock by electrodeposition of a paint film thereon from an aqueous bath containing a dispersion of cationic or anionic resinous vehicle, a dispersant for said resinous vehicle and a water-dispersible resin which is crosslinkable with said resinous vehicle upon curing, said water-dispersible resin being an aminoplast or phenoplast resin, wherein wet coated electrode stock is withdrawn continuously from said bath and force cured to make finished coated stock, the improvement for regulating flow of the freshly electrodeposited film before and during said force curing and thereby continuously producing finished coated stock virtually free from defects related to said flow which comprises:

establishing in said bath a dispersion of curing accelerator acid codepositable with said resinous vehicle, the pKa of said acid being not substantially above about 1 and the proportion of said acid being about that for yielding a substantially continuous cured film;
monitoring completeness of the resulting coating on the finished coated stock;
and,
in response to said monitoring, adjusting concentration of said acid in said bath adequately for maintaining substantially completely coated finished coated stock output.

1 more element

Dependencies are inferred from the claim text.