Coating technology

Abstract

The present invention provides an aqueous platinum electroplating bath including: a) a source of platinum ions; and b) a source of polyphosphate anions, and wherein the bath has a pH in the range from about 2 to about 9 when it is in use or ready for use. The aqueous platinum electroplating bath may optionally include one or more levellers. The invention also provides the use of the platinum electroplating bath and platinum salts suitable for use in the bath.

1 - 30 . (canceled) 
     
     
         31 . An aqueous platinum electroplating bath for depositing a coating of platinum on a substrate, the bath comprising:
 a) at least one platinum plating salt or complex; and   b) a source of polyphosphate anions,   and wherein the bath has a pH in the range from about 2 to about 9 when it is in use or ready for use.   
     
     
         32 . A bath according to  claim 31 , wherein the platinum plating salt or complex is selected from the group consisting of diammine dinitroplatinum(II), tetraammineplatinum(II) hydrogen orthophosphate, tetraamineplatinum(II) nitrate, tetraammineplatinum(II) hydrogen carbonate, tetraammineplatinum(II) hydroxide and tetraammineplatinum(II) sulphate. 
     
     
         33 . A bath according to  claim 31 , wherein the platinum plating salt or complex is selected from the group consisting of alkali metal hexahydroxyplatinates(IV), alkali metal tetranitroplatinates(II), alkali metal salts of hydrogen hexachloroplatinate(IV), alkali metal salts of hydrogen dinitrosulphatoplatinate(II), alkali metal tetrahaloplatinates(II) and tetraamineplatinum(II) halides. 
     
     
         34 . A bath according to  claim 31 , wherein the source of polyphosphate anions
 (a) is an alkali metal salt, alkaline earth metal salt or ammonium salt of a polyphosphoric acid, or a mixture thereof;   (b) is selected from the group consisting of disodium pyrophosphate dibasic, dipotassium pyrophosphate dibasic, tetrasodium pyrophosphate, tetrasodium pyrophosphate decahydrate, tetrapotassium pyrophosphate, potassium tripolyphosphate, sodium hexametaphosphate, lithium hexametaphosphate, lithium hexametaphosphate.6H 2 O, potassium hexametaphosphate, potassium pyrophosphate, sodium phosphate or a mixture thereof; or   (c) is a polyphosphoric acid.   
     
     
         35 . A bath according to  claim 31 , wherein the source of platinum ions and the source of polyphosphate anions is a platinum polyphosphate salt or complex, optionally selected from the group consisting of tetraammineplatinum(II) dihydrogen pyrophosphate, di[tetraammineplatinum(II)]pyrophosphate, Na 2 [Pt(NH 3 ) 4 ][H 2 P 2 O 7 ] and mixtures thereof. 
     
     
         36 . A bath according to  claim 31 , wherein the platinum ion concentration is about 1 to about 30 g/litre, and/or wherein the polyphosphate ion concentration is about 0.1 to about 90 g/litre. 
     
     
         37 . A bath according to  claim 31  further comprising at least one leveller, wherein the leveller optionally comprises at least one unsaturated carbon-carbon or unsaturated carbon-heteroatom bond. 
     
     
         38 . A bath according to  claim 37 , wherein the leveller is selected from the group consisting of at least one:
 a) substituted or unsubstituted saccharine or salt thereof;   b) substituted or unsubstituted benzopyranone;   c) substituted or unsubstituted benzaldehyde or derivative thereof;   d) substituted or unsubstituted alkene provided the alkene is not ethylene;   e) substituted or unsubstituted alkyne provided the alkyne is not acetylene;   f) substituted or unsubstituted alkylnitrile;   g) substituted or unsubstituted pyridine or addition salt thereof;   h) substituted or unsubstituted triazole; and   i) substituted or unsubstituted pyridinium salt.   
     
     
         39 . A bath according to  claim 37 , wherein the leveller is:
 (a) a compound of formula (1) or salts thereof:   
       
         
           
           
               
               
           
         
         wherein m is 0, 1, 2, 3 or 4; 
         each R 1  is independently an unsubstituted C 1 -C 10  alkyl group; 
         R 2  is selected from the group consisting of H, unsubstituted C 1 -C 10  alkyl, an alkali metal ion and an alkaline earth metal ion; or 
         (b) a compound of formula (2a), (2b) or (2c): 
       
       
         
           
           
               
               
           
         
         wherein n is 0, 1, 2, 3 or 4; 
         p is 0, 1 or 2; 
         each R 10  and R 11  is independently selected from an unsubstituted C 1 -C 10  alkyl group; or 
         (c) a compound of formula (3a) or (3b): 
       
       
         
           
           
               
               
           
         
         wherein R 20  is selected from the group consisting of H and —OR 23 ; and 
         R 21  and R 22  are independently selected from the group consisting of H, —C(O)R 24  and unsubstituted C 1 -C 10 -alkyl; and 
         R 23  and R 24  are independently selected from the group consisting of H and unsubstituted C 1 -C 10 -alkyl; or 
         (d) a compound of formula (4): 
       
       
         
           
           
               
               
           
         
         wherein each R 30 , R 31 , R 32  and R 33  is independently selected from the group consisting of H, unsubstituted C 1 -C 10 -alkyl, substituted C 1 -C 10 -alkyl, —CO 2 R 34 , —NR 34 R 35 , —CONR 34 R 35  and —CN, provided that R 30 , R 31 , R 32  and R 33  are not all H, wherein the substituents are selected from the group consisting of at least one —OH, —CO 2 R 36 , —OC(O)R 36 , —NR 36 R 37 , —CONR 36 R 37 , —CN, —SO 3   − Na +  and —SO 3   − K + ; 
         R 34  and R 35  are independently selected from the group consisting of H and unsubstituted C 1 -C 10 -alkyl; and 
         R 36  and R 37  are independently selected from the group consisting of H and unsubstituted C 1 -C 10 -alkyl; or 
         (e) a compound of formula (5): 
       
       
         
           
           
               
               
           
         
         wherein R 40  and R 41  are independently selected from the group consisting of H, unsubstituted C 1 -C 10 -alkyl and substituted C 1 -C 10 -alkyl, provided that R 40  and R 41  are not both H, 
         wherein the substituents are selected from the group consisting of at least one of —OH, —CO 2 R 42 , —OC(O)R 42 , —NR 42 R 43 , —CONR 42 R 43 , —CN, —SO 3   − Na +  and —SO 3   − K + ; 
         R 42  and R 43  are independently selected from the group consisting of H and unsubstituted C 1 -C 10 -alkyl; or 
         (f) a compound of formula (6):
   R 50 —CN  (6)
 
 
         wherein R 50  is a substituted or unsubstituted and the substituents are selected from the group consisting of at least one of —OR 51 , —CO 2 R 51 , —OC(O)R 51 , —NR 51 R 52  and —CN; and 
         wherein R 51  and R 52  are independently selected from the group consisting of H and unsubstituted C 1 -C 10 -alkyl; or 
         (g) a compound of formula (7a), (7b) or (7c): 
       
       
         
           
           
               
               
           
         
         wherein R 60  and R 61  are independently selected from the group consisting of —OH, —CN, —CONR 62 R 63 , —CO 2 R 62 , —COR 63 , N-(unsubstituted C 1 -C 10 -alkyl)-pyrrolidinyl, unsubstituted C 1 -C 10 -alkyl, substituted C 1 -C 10 -alkyl, unsubstituted C 2 -C 10 -alkenyl, substituted C 2 -C 10 -alkenyl, —SO 2 —R 63 , —N═N-(unsubstituted C 6 -C 10 -aryl), —N═N-(substituted C 6 -C 20 -aryl), unsubstituted pyridyl, substituted pyridyl, 
         wherein the substituents are independently selected from the group consisting of at least one of —CN, —CONR 64 R 65 , —COR 65 , —CO 2 R 64 , —OH, —NR 64 R 65  and ═NR 64 ; 
         R 62  is selected from the group consisting of H, —OH and unsubstituted C 1 -C 10 -alkyl; 
         R 63  is selected from the group consisting of H, —OH, unsubstituted C 1 -C 10 -alkyl, unsubstituted C 1 -C 10 -alkyl-CO 2 H, —NH 2 , —NH(unsubstituted C 1 -C 10 -alkyl), —N(unsubstituted C 1 -C 10 -alkyl) 2 ; 
         R 64  is selected from the groups defined for R 62 ; 
         R 65  is selected from the groups defined for R 63 ; 
         each x is 0, 1, 2 or 3; and 
         each y is 0, 1, 2, 3 or 4; or 
         (h) a compound of formula (8): 
       
       
         
           
           
               
               
           
         
         wherein R 70  is selected from a group consisting of H, —CO 2 R 72  and —NR 72 R 73 ; 
         R 71  is selected from a group consisting of H and unsubstituted C 1 -C 10 -alkyl; 
         R 72  and R 73  are independently selected from the group consisting of H and unsubstituted C 1 -C 10 -alkyl; 
         one of X 1  and X 2  is C—R 74  and the other of X 1  and X 2  is N; and 
         R 74  is selected from a group as defined for R 70 ; or 
         (i) a compound of formula (9a), (9b) or (9c): 
       
       
         
           
           
               
               
           
         
         wherein R 60  and R 61  are independently selected from the group consisting of —OH, —CN, —CONR 62 R 63 , —CO 2 R 62 , —COR 63 , N-(unsubstituted C 1 -C 10 -alkyl)-pyrrolidinyl, unsubstituted C 1 -C 10 -alkyl, substituted C 1 -C 10 -alkyl, unsubstituted C 2 -C 10 -alkenyl, substituted C 2 -C 10 -alkenyl, —SO 2 —R 63 , —N═N-(unsubstituted C 6 -C 10 -aryl), —N═N-(substituted C 6 -C 20 -aryl), unsubstituted pyridyl, substituted pyridyl, 
         wherein the substituents are independently selected from the group consisting of at least one —CN, —CONR 64 R 65 , —COR 65 , —CO 2 R 64 , —OH, —NR 64 R 65  and ═NR 64 ; 
         R 62  is selected from the group consisting of H, —OH and unsubstituted C 1 -C 10 -alkyl; 
         R 63  is selected from the group consisting of H, —OH, unsubstituted C 1 -C 10 -alkyl, unsubstituted C 1 -C 10 -alkyl-CO 2 H, —NH 2 , —NH(unsubstituted C 1 -C 10 -alkyl), —N(unsubstituted C 1 -C 10 -alkyl) 2 ; 
         R 64  is selected from the groups defined for R 62 ; 
         R 65  is selected from the groups defined for R 63 ; 
         R 82  is selected from the group consisting of —O −  and unsubstituted C 1 -C 10 -alkyl; 
         Z is a counterion when R 82  is an unsubstituted C 1 -C 10 -alkyl; 
         each x is 0, 1, 2 or 3; and 
         each y is 0, 1, 2, 3 or 4; or 
         (j) at least one substituted or unsubstituted polyalkyleneimines. 
       
     
     
         40 . A bath according to any  claim 31 , further comprising one or more other platinum group metal or base metal plating salts or complexes. 
     
     
         41 . A bath according to  claim 31 , wherein the rate of plating is about ≧0.5 microns thickness of platinum or platinum alloy per hour. 
     
     
         42 . A bath according to  claim 31 , wherein the bath is used at temperatures from about room temperature to about 100° C. 
     
     
         43 . A bath according to  claim 31  further comprising one or more brighteners, surfactants or wetting agents. 
     
     
         44 . A platinum salt which is tetraammineplatinum(II) dihydrogen pyrophosphate, di[tetraammineplatinum(II)]pyrophosphate or Na 2 [Pt(NH 3 ) 4 ][H 2 P 2 O 7 ]. 
     
     
         45 . A method for plating platinum or a platinum alloy onto a substrate, comprising:
 providing an aqueous platinum electroplating bath according to  claim 31 ; and   plating the platinum or platinum alloy onto the substrate using the bath.   
     
     
         46 . A bath according to  claim 32 , wherein the source of polyphosphate anions
 (a) is an alkali metal salt, alkaline earth metal salt or ammonium salt of a polyphosphoric acid, or a mixture thereof;   (b) is selected from the group consisting of disodium pyrophosphate dibasic, dipotassium pyrophosphate dibasic, tetrasodium pyrophosphate, tetrasodium pyrophosphate decahydrate, tetrapotassium pyrophosphate, potassium tripolyphosphate, sodium hexametaphosphate, lithium hexametaphosphate, lithium hexametaphosphate.6H 2 O, potassium hexametaphosphate, potassium pyrophosphate, sodium phosphate or a mixture thereof; or   (c) is a polyphosphoric acid.   
     
     
         47 . A bath according to  claim 33 , wherein the source of polyphosphate anions
 (a) is an alkali metal salt, alkaline earth metal salt or ammonium salt of a polyphosphoric acid, or a mixture thereof;   (b) is selected from the group consisting of disodium pyrophosphate dibasic, dipotassium pyrophosphate dibasic, tetrasodium pyrophosphate, tetrasodium pyrophosphate decahydrate, tetrapotassium pyrophosphate, potassium tripolyphosphate, sodium hexametaphosphate, lithium hexametaphosphate, lithium hexametaphosphate.6H 2 O, potassium hexametaphosphate, potassium pyrophosphate, sodium phosphate or a mixture thereof; or   (c) is a polyphosphoric acid.   
     
     
         48 . A bath according to any  claim 32 , wherein the platinum ion concentration is about 1 to about 30 g/litre, and/or wherein the polyphosphate ion concentration is about 0.1 to about 90 g/litre. 
     
     
         49 . A bath according to any  claim 33 , wherein the platinum ion concentration is about 1 to about 30 g/litre, and/or wherein the polyphosphate ion concentration is about 0.1 to about 90 g/litre. 
     
     
         50 . A bath according to any  claim 34 , wherein the platinum ion concentration is about 1 to about 30 g/litre, and/or wherein the polyphosphate ion concentration is about 0.1 to about 90 g/litre.