Method for treating surface of plastic

Abstract

Provided is a Cr-free plastic surface treatment method which can provide a plating film sufficiently adhered to a plastic surface. The plastic surface treatment method includes treating plastic with a solution obtained by electrolyzing sulfuric acid. It is preferable that the sulfuric acid concentration of the sulfuric acid solution is 50 to 92 wt %, the persulfuric acid concentration is not less than 3 g/L, and the treatment temperature is not lower than 80° C., for example, 80 to 140° C., particularly 100 to 130° C. By immersing plastic in this sulfuric acid solution for 1 minute to 10 minutes, hydrophilic functional groups are exposed on the surface of the plastic.

1 . A method for treating a surface of a plastic comprising treating a plastic with a solution obtained by electrolyzing sulfuric acid. 
     
     
         2 . The method for treating a surface of a plastic according to  claim 1 , wherein the solution has a concentration of the sulfuric acid of 50 to 92 wt %. 
     
     
         3 . The method for treating a surface of a plastic according to  claim 1 , wherein a treatment temperature is 80 to 140° C. 
     
     
         4 . The method for treating a surface of a plastic according to  claim 1 , wherein the solution contains persulfuric acid at a concentration of 3 to 20 g/L. 
     
     
         5 . The method for treating a surface of a plastic according to  claim 1 , the plastic being treated in a treatment equipment comprising a treatment tank for storing a sulfuric acid-containing treatment solution and an electrolytic cell for forming persulfuric acid, the sulfuric acid-containing treatment solution being circulated between the treatment tank and the electrolytic cell, wherein the plastic is immersed in the treatment tank to treat the surface of the plastic.