Method for treating plastic surface

Abstract

Treatment equipment has a treatment tank provided with a thermostatic heater on its outer periphery and a supply tank connected through a pipe and a pump. The treatment tank and the supply tank are filled with persulfate solutions S and S1 having predetermined sulfuric acid concentrations and persulfuric acid concentrations respectively. In the treatment tank, a plastic plate is vertically hung as plastic to be treated. The sulfuric acid concentrations of the persulfate solutions S and S1 are each 50 to 92 wt %. The persulfuric acid concentrations of the solutions S and S1 are each 3 to 20 g/L after the persulfate is dissolved. According to a Cr-free method for treating a plastic surface using such treatment equipment, it becomes possible to form a plating film that sufficiently adheres to the plastic surface.

1 . A method for treating a plastic surface comprising treating plastic with a solution containing a persulfate dissolved therein, the solution having a sulfuric acid concentration of 50 to 92 wt % and a persulfuric acid concentration of 3 to 20 g/L. 
     
     
         2 . The method for treating a plastic surface according to  claim 1 , wherein a mixed solution containing an inorganic salt dissolved therein is used as the solution containing a persulfate dissolved therein. 
     
     
         3 . The method for treating a plastic surface according to  claim 1 , wherein the treatment temperature is 50 to 140° C. 
     
     
         4 . The method for treating a plastic surface according to  claim 1  comprising, by using a treatment equipment comprising a treatment tank for storing the solution containing a persulfate dissolved therein and a persulfate solution storage tank for supplying the solution containing a persulfate dissolved therein to the treatment tank, immersing plastic in the treatment tank to thereby treat a surface of the plastic.