Process for metallizing plastic surfaces

Abstract

The invention relates to a process for coating plastic surfaces with metals, especially plastic surfaces composed of acrylonitrile/butadiene/styrene copolymers (ABS) and composed of mixtures of these copolymers with other plastics (ABS blends), using an etch solution (composition C) comprising at least one ionic liquid IL, wherein the process comprises the treating of the plastic surface after the etching with an aqueous rinse solution RS while applying ultrasound.

1 . A process for coating a plastic surface with at least one metal, the process comprising:
 a) pretreating the plastic surface with a composition, comprising more than 50% by weight of an ionic liquid, wherein the ionic liquid is a salt which is liquid at 100° C., 1 bar;   b) primary treating the plastic surface from a) with an aqueous rinse solution while applying ultrasound;   c) secondary treating the plastic surface from b) with an activator composition, comprising an ionogenic activator, a colloidal activator or both of the ionogenic and the colloidal activator;   d) tertiary treating the plastic surface from c) with an accelerator composition, comprising an acid, a reducing agent, or both of the acid and the reducing agent;   e) chemically depositing a metal layer, by treating the plastic: surface from d) with a first coating composition, comprising a metal salt and a reducing agent;   f) electrochemically coating the plastic surface from e) with at least one additional metal layer, by electrochemically treating the plastic surface from step e) with at least one second coating composition, comprising a metal compound.   wherein the plastic surface is a plastic comprising a polyimide, a polystyrene, a copolymer of styrene selected from a styrene/acrylonitrile copolymer, an acrylic ester/styrene/acrylonitrile copolymer and an acrylonitrile/butadiene/styrene copolymer, or a mixture thereof and/or a multicomponent plastic comprising the plastic.   
     
     
         2 . (canceled) 
     
     
         3 . The process according to  claim 1 , wherein the ionic liquid is at least one salt having a cation selected from the group consisting of an imidazolium cation, a pyridinium cation, a pyrazolium cation and an alkylammonium cation. 
     
     
         4 . The process according to  claim 1 , wherein the ionic liquid is a salt having an alkylammonium cation of formula (I): 
       
         
           
           
               
               
           
         
         wherein 
         R is an unbranched and unsubstituted C 1 -C 18 -alkyl, CH 3 O—(CH 2 CH 2 O) p —CH 2 CH 2 — or CH 3 CH 2 O—(CH 2 CH 2 O) p —CH 2 CH 2 — with p=0 to 3; 
         R 1 , R 2  and R 3  are each independently:
 a hydrogen atom, unsubstituted C 1 -C 18 -alkyl, 2-hydroxyethyl, 2-cyanoethyl, 2-(methoxycarbonyl)ethyl, 2-(ethoxycarbonyl)ethyl, 2-(n-butoxycarbonyl)ethyl, chlorine, CH 3 O—(CH 2 CH 2 O) p —CH 2 CH 2 — or CH 3 CH 2 O—(CH 2 CH 2 O)—CH 2 CH 2 — with p=0 to 3, 
 or two adjacent R 1 , R 2  and R 3  radicals together with a nitrogen atom in formula (I) form a saturated unsubstituted five- to seven-membered ring; 
 
         X is an anion; and 
         n is 1, 2 or 3. 
       
     
     
         5 . The process according to  claim 1 , wherein the ionic liquid is methyltri(1-butyl)ammonium methylsulfate. 
     
     
         6 . The process according to  claim 1 , wherein the ionic liquid comprises a first ionic liquid and a second ionic liquid,
 the first ionic liquid comprises, as a cation, at least one an alkylammonium cation, and   the second ionic liquid comprises, as a cation, an aromatic heterocycle having a delocalized cationic charge and a nitrogen atom.   
     
     
         7 . The process according to  claim 1 , wherein the ionic liquid is at least one selected from the group consisting of methyltri(1-butyl)ammonium methylsulfate. 1-ethyl-3-methylimidazolium methylsulfate, 1-ethyl-3-methylimidazolium ethylsulfate, 1-ethyl-3-methylimidazolium hydrogensulfate, -ethyl-3-methylimidazolium thiocyanate, 1-ethyl-3-methylimidazolium acetate, 1-ethyl-3-methylimidazolium methanesulfonate and 1-ethyl-3-methylimidazolium diethylphosphate. 
     
     
         8 . The process according to  claim 1 , wherein the composition comprises 1% to 30% by weight, based on an overall composition, of at least one solvent selected from the group consisting of water, propylene carbonate, polyethylene glycols, diacetin, triacetin, ethylene glycol, diethylene glycol, triethylene glycol and tetraethylene glycol. 
     
     
         9 . The process according to  claim 1 , wherein the composition comprises, based on an overall composition:
 49% to 94% by weight of a first ionic liquid, which comprises an alkylammonium cation;   5% to 50% by weight of a second ionic liquid comprising, as a cation, an aromatic heterocycle having a delocalized cationic charge and a nitrogen atom; and   1% to 30% by weight of at least one solvent selected from the group consisting of water, propylene carbonate, polyethylene glycols, diacetin, triacetin, ethylene glycol, diethylene triethylene glycol and tetraethylene glycol.   
     
     
         10 . (canceled) 
     
     
         11 . The process according to  claim 1 , wherein the metal is at least one selected from nickel, aluminium, copper, chromium, tin, zinc and an alloy thereof. 
     
     
         12 . The process according to  claim 1 , wherein the plastic surface is a plastic comprising an acrylonitrile/butadiene/styrene copolymer, and
 the pretreating is carried out at a temperature in the range from 50 to 60° C. and over a period of 5 to 15 min.   
     
     
         13 . The process according to  claim 1 , wherein the prim, treating in b) is carried out by dipping the plastic surface from a) into an ultrasound bath comprising the aqueous rinse solution at a power in the range from 40 to 60 watts/L, over a period of 1 to 30 min and at a temperature of 40 to 60° C., and
 wherein the aqueous rinse solution comprises at least 85% by weigh of water. 
 
     
     
         14 . The process according to  claim 1 , wherein b) comprises:
 b1) treating the plastic surface from a) with a first aqueous rinse solution, by spraying the plastic surface with the first aqueous rinse solution or dipping the plastic surface into the first aqueous rinse solution; and   b2) treating the plastic surface from b1) with a second aqueous rinse solution while applying ultrasound.   
     
     
         15 . The process according to  claim 1 , wherein the electrochemical coating in step f) comprises:
 f1) electrochemically coating the plastic surface from e) with a layer consisting essentially of copper, nickel, or both of the copper and the nickel, by treating the plastic surface from e) with a third coating, composition, comprising a copper compound, a nickel compound, or both of the copper compound and the nickel compound; and   f2) electrochemically coating the plastic surface from f1) with a layer consisting essentially of chromium, by (eating the surface from f1) with a fourth coating composition, comprising a chromium compound.   
     
     
         16 . The process according to  claim 1 , wherein the plastic surface is a plastic consisting of a polyamide, a polystyrene, a copolymer of styrene selected from a styrene/acrylonitrile copolymer, an acrylic ester/styrene/acrylonitrile copolymer and an acrylonitrile/butadiene/styrene copolymer, or a mixture thereof and/or a multicomponent plastic comprising the plastic. 
     
     
         17 . The process according to  claim 12 , wherein the plastic surface is a plastic consisting of an acrylonitrile/butadiene/styrene copolymer.