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Paint adhesion on chrome plated plastic part

May 12, 2010

Dear Sir,

I'm the technician of a company that metallizes thermoplastic parts (ABS material) by electrolytic plating process, commonly known as Chrome Plating.

Once we have the plated part, we paint it. We use an airbrush painting process applied directly, without primer.

Unfortunately this painting process is not a very robust process because some parts pass the adhesion tests required while other parts not. All the parts have been produced under the same injection moulding machines, in the same plating lines and in the same paint facilities, in addition having used the same materials.

We have investigated about the parameters that interfere with the adhesion of paint on a surface of chromium, and we have located the patent US2007/0092741 which states:

"The coating film made of the coating material composition has high adhesion to the chromium plated surface immediately after coating, but has such a problem that adhesion to a chromium plated material, which has reduced adhesion caused by adherent residues in the chromium plating step or storage environment before coating, is reduced and thus peeling of the coating film occurs."

For our side, we have proceeded to clean and store the chrome parts equally, and some pieces pass the tests while other pieces not, although all the parts are from the same batch, having been painted at the same time.

Therefore, I proceed to ask if you know the factors affecting the adhesion between paint and the layer of chromium, and how they affect to this adhesion.

Thanks in advance

Francisco Lopez
Technician - Spain