Method for electrochemically covering an insulating substrate

Abstract

The present invention relates to a process for obtaining a metal, ceramic or composite coating on the surface of a non-conductive material such as plastic, ceramic or wood which comprises: A) preparing a polypyrrole dispersion in aqueous base paint or in an acid type water-soluble pure resin; B) diluting the dispersion resulting from the previous stage with an alcohol in a factor of 1.5; C) applying the dispersion of the conductive polymer resulting from stage B) on the surface to be coated and drying same; and D) obtaining the metal, ceramic or composite coating by means of an electrolytic process or an electrophoretic deposition.

1 . Process for obtaining a metal, ceramic or composite coating on the surface of a non-conductive material which comprises the following stages:
 A) preparing a polypyrrole dispersion in aqueous base paint or in an acid type water-soluble pure resin;   B) diluting the dispersion resulting from the previous stage with an alcohol in a factor of 1.5;   C) applying the dispersion resulting from stage B) on the surface to be coated and drying same; and   D) obtaining the metal, ceramic or composite coating by means of an electrolytic process or an electrophoretic deposition.   
     
     
         2 . Process according to  claim 1 , wherein stage A) comprises:
 A-1) obtaining polypyrrole in aqueous medium from pyrrole;   A-2) taking the resulting dispersion to dryness; and   A-3) redispersing the resulting dry material in aqueous base paint or in an acid type water-soluble pure resin until reaching a concentration comprised between 0.05 and 2.5 g of polypyrrole/g of paint or resin.   
     
     
         3 . Process according to  claim 2 , wherein stage A-1) is performed starting from pyrrole in aqueous medium at a concentration comprised between 1×10 −4  and 1×10 −1  g/ml; and an anionic dispersant with a molecular weight comprised between 10,000 and 1,000,000 g/mol; the mixture is submerged in a bath at a temperature below 0° C. and stirred by ultrasound; an oxidizer dissolved in water is added; the polymerization takes place at room temperature with mechanical stirring, for a time comprised between half an hour and 7 hours. 
     
     
         4 . Process according to  claim 2 , wherein stage A-2) comprises lyophilizing or treating in a rotary evaporator the polypyrrole dispersion obtained in stage A-1). 
     
     
         5 . Process according to  claim 2 , wherein stage A-3) comprises dispersing the dry material obtained in A-2) in a aqueous base paint or in an acid type water-soluble pure resin, reaching a concentration comprised between 0.05 and 2.5 g of polypyrrole/g of paint or resin. 
     
     
         6 . Process according to the  claim 1 , wherein in stage B) the polypyrrole dispersion obtained in stage A) is then diluted with an alcohol in a factor of 1.5. 
     
     
         7 . Process according to  claim 1 , wherein stage C) of applying the dispersion of polypyrrole to a part is performed by the immersion of said part, painting or spraying and subsequent drying. 
     
     
         8 . Process according to  claim 1 , wherein stage D) comprises obtaining a metal coating on the surface to which the polypyrrole has been applied, by means of an electrolytic process in a simple cell containing an electrolyte with direct current or by means of current pulses. 
     
     
         9 . Process according to  claim 1 , wherein stage D) comprises obtaining a composite coating on the surface to which the polypyrrole has been applied, by means of an electrolytic process in a simple cell containing an electrolyte which comprises at least one metal salt and at least one ceramic particle. 
     
     
         10 . Process according to  claim 1 , wherein stage D) comprises obtaining a ceramic coating on the surface to which the polypyrrole has been applied, by means of an electrophoretic deposition in a simple cell containing a suspension of ceramic particles in an aqueous medium. 
     
     
         11 . Process according to  claim 10 , wherein the concentration of ceramic particles in the suspension is comprised between 1-60% by weight with respect to the total weight of the suspension and between 0.1-2% by weight with respect to total weight of the suspension of additives. 
     
     
         12 . Process according to  claim 10 , wherein a potential comprised between 20 and 400 V is applied for a time comprising between 1 and 40 minutes. 
     
     
         13 . Process according to  claim 10 , wherein after the electrophoretic deposition the part obtained is sintered at a temperature comprised between 400° C. and 1500° C.