Electrodeposition of silver with fluoropolymer nanoparticles

Abstract

Electrolytic plating compositions and electrolytic plating processes for the co-deposition of silver or silver alloy with fluoropolymer nanoparticles are provided. The silver or silver alloy composite coating containing fluoropolymer nanoparticles has enhanced functional properties such as a reduced coefficient of friction. The electrolytic plating composition comprises: (a) a silver ion source comprising silver methane sulfonate (Ag-MSA); (b) a complexing agent comprising a compound comprising a nitrogen-containing heterocyclic ring; (c) a pre-mix dispersion comprising fluoropolymer nanoparticles particles having a mean particle size of from about 10 nm and about 500 nm and a surfactant; and (d) an auxiliary surfactant comprising a cationic fluorosurfactant, wherein the composition has a pH of from about 8 to about 14.

1 . An electrolytic plating composition for depositing a composite silver or silver alloy coating on a substrate comprising:
 (a) a silver ion source comprising silver methane sulfonate (Ag-MSA);   (b) a complexing agent comprising a compound comprising a nitrogen-containing heterocyclic ring;   (c) a pre-mix dispersion comprising fluoropolymer nanoparticles particles having a mean particle size of from about 10 nm and about 500 nm and a surfactant; and   (d) an auxiliary surfactant comprising a cationic fluorosurfactant, wherein the composition has a pH of from about 8 to about 14.   
     
     
         2 . The electrolytic plating composition of  claim 1  wherein the auxiliary surfactant further comprises an anionic fluorosurfactant. 
     
     
         3 . The electrolytic plating composition of  claim 1  wherein the electrolytic plating composition is essentially free of any nonionic fluorosurfactants. 
     
     
         4 . (canceled) 
     
     
         5 . The electrolytic plating composition of  claim 2  wherein the cationic fluorosurfactant comprises a fluoroalkyl ammonium halide surfactant. 
     
     
         6 . The electrolytic plating composition of  claim 1  wherein the fluoropolymer nanoparticles have a specific surface area between about 15 m 2 /g and about 50 m 2 /g. 
     
     
         7 . (canceled) 
     
     
         8 . The electrolytic plating composition of  claim 1  wherein the electrolytic plating composition comprises about one gram of cationic fluorosurfactant for every about 20 m 2  to about 80 m 2  of surface area of fluoropolymer particle. 
     
     
         9 .- 19 . (canceled) 
     
     
         20 . The electrolytic plating composition of  claim 1  wherein the compound comprising the nitrogen-containing heterocyclic ring is selected from the group consisting of substituted and unsubstituted hydantoin and substituted and unsubstituted succinimide. 
     
     
         21 . The electrolytic plating composition of  claim 1  wherein the complexing agent comprises succinimide. 
     
     
         22 . The electrolytic plating composition of  claim 1  wherein the complexing agent comprises a hydantoin compound of formula I 
       
         
           
           
               
               
           
         
       
       wherein R 1 , R 2 , R 3 , and R 4  are independently hydrogen, an alkyl group having 1 to 5 carbon atoms, a hydroxyalkyl group having 1 to 5 carbon atoms, or a substituted or unsubstituted aryl group. 
     
     
         23 .- 36 . (canceled) 
     
     
         37 . The electrolytic plating composition of  claim 1  wherein:
 the auxiliary surfactant further comprises an anionic fluorosurfactant; 
 the electrolytic plating composition is essentially free of any nonionic fluorosurfactants; 
 the cationic fluorosurfactant comprises a fluoroalkyl ammonium halide surfactant in a concentration from about 0.5 g/L to about 10 g/L and about one gram of cationic fluorosurfactant for every about 10 m 2  to about 80 m 2  surface area of fluoropolymer particle; 
 the fluoropolymer nanoparticles have a specific surface area between about 15 m 2 /g and about 50 m 2 /g, a mean particle size of from about 10 nm to about 200 and a concentration of between about 2 g/L and 200 g/L; 
 the silver ion concentration is from about 10 g/L to about 100 g/L; 
 the compound comprising the nitrogen-containing heterocyclic ring is selected from the group consisting of substituted and unsubstituted hydantoin and substituted and unsubstituted succinimide; 
 the electrolytic plating composition further comprises a wetting agent comprising sulfopropylated polyalkoxylated beta-naphthol, condensation products of naphthalenesulfonic acid, or salts thereof; 
 the electrolytic plating composition further comprises a sulfonic acid and/or a derivative of a sulfonic acid at a concentration between 50 g/L and 500 g/L; 
 the electrolytic plating composition further comprises about 30 mg/L to about 500 mg/L of potassium bromide; 
 the electrolytic plating composition has a pH from about 9.5 to about 11.5, or from about 9 to about 11. 
 
     
     
         38 . A process for applying a silver or silver alloy composite coating onto a substrate surface, the process comprising:
 contacting the substrate surface with an electrolytic plating composition of  claim 1  and   applying an external source of electrons to the electrolytic plating composition to thereby electrolytically deposit the composite coating onto the substrate surface, wherein the composite coating comprises silver or silver alloy and the fluoropolymer nanoparticles.   
     
     
         39 . The process of  claim 38  wherein the composite coating has a coefficient of friction, from about 0.05 to about 0.3. 
     
     
         40 . The process of  claim 38  or  39  wherein the composite coating contains at least 4.0 wt. % of fluorine (atomic). 
     
     
         41 . (canceled) 
     
     
         42 . The process of  claim 40  wherein the composite coating has a contact resistance less than about 5 milliohms. 
     
     
         43 .- 47 . (canceled) 
     
     
         48 . The process of  claim 42  wherein the composite coating has a thickness from about 1 μm to about 10 μm. 
     
     
         49 . (canceled) 
     
     
         50 . A process for preparing an electrolytic plating composition, the process comprising:
 (1) mixing a complexing agent comprising a hydantoin compound, any wetting agent and conductive salt, and water to form a solution;   (2) mixing a silver ion source comprising Ag-MSA in the solution;   (3) mixing an auxiliary surfactant and any alkali bromide in the solution;   (4) following steps (1)-(3), mixing a pre-mix dispersion comprising fluoropolymer nanoparticles particles having a mean particle size of from about 10 nm and about 500 nm and a surfactant along with any antifoam additive in the solution to form the electrolytic plating composition; and   (5) optionally maintaining the pH of the mixture at about 9 to about 10 by addition of base.   
     
     
         51 .- 52 . (canceled)