Chrome-free adhesion pre-treatment for plastics

A method of pretreating a 0%-30% glass fibers filled polyetherimide substrate for metallization, the method comprising:

• contacting a surface of the substrate for 2 minutes to 30 minutes with a first composition comprising nitric acid at a concentration of 10.4 Moles/L (M/L) to 13.0 M/L to form a first treated surface;
• and
• contacting the first treated surface for 4 minutes to 30 minutes with a second composition comprising sulfuric acid at a concentration of 16.0 M/L to 17.2 M/L, and periodate ions at a concentration of 0.03 M/L to 0.2 M/L, to produce an adherent surface on the substrate for metallization;
• wherein
• the method is free of chromium ions;
• the method is free of a mechanical abrasion step;
• and
• the adherent surface upon metallization exhibits an adhesion of metal of 1.5 N/mm or greater when measured according to ASTM International Test Method B533-85 (2013).

A method of metallizing a surface of a plastic or polymer article, the method comprising:

• (a) pretreating the surface of the plastic or polymer article to yield an adherent surface;
• (b) activating the adherent surface by applying an electroconductive layer;
• and
• (c) applying a metal coating to yield a metallized surface exhibiting an adhesion of metal of 1.5 N/mm or greater when measured according to ASTM International Test Method B533-85 (2013);
• wherein, the method is free of chromium ions, the surface of the plastic or polymer article is 0%-30% glass fibers filled polyetherimide, and the pretreating comprises:
• contacting the surface of the plastic or polymer article for 2 minutes to 30 minutes with a first composition comprising nitric acid at a concentration of 10.4 Moles/L (M/L) to 13.0 M/L to form a first treated surface;
• and
• contacting the first treated surface for 4 minutes to 30 minutes with a second composition comprising sulfuric acid at a concentration of 16.0 M/L to 17.2 M/L, and periodate ions at a concentration of 0.03 M/L to 0.2 M/L, to produce the adherent surface.