Title: Leveling agent for acid zinc electroplating baths and method

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Claims: The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. An aqueous acidic plating bath for the electrodeposition of a zinc coating on a substrate which comprises zinc ions, and an amount, sufficient to provide a level zinc electrodeposit, of one or more bath-soluble leveling phosphorus cations having the formula:

R.sub.4 P.sup. .sym.

wherein each R is independently a hydroxy alkyl group.

2. The plating bath of claim 1 wherein each R is the hydroxy methyl group.

3. The plating bath of claim 1 wherein the bath also contains at least one nitrogen-containing compound obtained by reacting (a) ammonia, an aliphatic amine containing at least one primary amine group, or mixtures of two or more of any of these with (b) one or more epihalohydrins, glycerol halohydrins, or mixtures thereof.

4. The plating bath of claim 3 wherein the nitrogen-containing compound is obtained by reacting ammonia with epichlorohydrin.

5. The plating bath of claim 4 wherein the molar ratio of ammonia and epichlorohydrin is at least about 2:1.

6. The plating bath of claim 5 wherein the ammonia and epichlorohydrin are reacted in the presence of water at a temperature below about 60.degree. C.

7. The plating bath of claim 3 wherein the nitrogen-containing compound is obtained by reacting ethylene diamine with epichlorohydrin.

8. The plating bath of claim 7 wherein the molar ratio of ethylene diamine and epichlorohydrin is at least about 1:1.

9. The plating bath of claim 7 wherein the ethylene diamine and epichlorohydrin are reacted in the presence of water at a temperature below about 60.degree. C.

10. The plating bath of claim 3 also containing at least one thiourea having the general formula:

[R'.sub.2 N].sub.2 CH

wherein each R' is independently hydrogen or an alkyl or alkenyl group.

11. The plating bath of claim 10 wherein R' is hydrogen.

12. The plating bath of claim 3 wherein (a) and (b) are reacted in the presence of water at a temperature below about 60.degree. C.

13. An aqueous acidic plating bath for the electrodeposition of a zinc coating on a substrate which comprises zinc ions and an amount, sufficient to provide a level zinc electrodeposit, of one or more bath-soluble phosphorus cations having the general formula:

[R"CH(OH).sub.4 ]P.sup. .sym.

wherein each R" is independently hydrogen or a lower alkyl group.

14. The plating bath of claim 13 wherein R" is hydrogen.

15. The plating bath of claim 13 wherein the bath also contains at least one nitrogen-containing compound obtained by reacting (a) ammonia, an aliphatic amine containing at least one primary amine group or mixtures of two or more of any of these, with (b) one or more epihalohydrins, glycerol halohydrins, or mixtures thereof.

16. The plating bath of claim 15 wherein the nitrogen-containing compound is obtained by reacting ammonia with epichlorohydrin.

17. The plating bath of claim 16 wherein the molar ratio of ammonia and epichlorohydrin is about at least 2:1.

18. The plating bath of claim 17 wherein the ammonia and epichlorohydrin are reacted in the presence of water at a temperature, below about 60.degree. C.

19. The pating bath of claim 15 wherein the nitrogen-containing compound is obtained by reacting ethylene diamine with epichlorohydrin.

20. The plating bath of claim 19 wherein the molar ratio of ethylene diamine and epichlorohydrin is at least about 1:1.

21. The plating bath of claim 20 wherein the ethylene diamine and epichlorohydrin are reacted in the presence of water at a temperature below about 60.degree. C.

22. The plating bath of claim 15 also containing at least one thiourea having the general formula:

[R'.sub.2 N].sub.2 CS

wherein each R' is independently hydrogen, an alkyl, or an alkenyl group.

23. The plating bath of claim 22 wherein R' is hydrogen.

24. The plating bath of claim 15 wherein (a) and (b) are reacted in the presence of water at a temperature below about 60.degree. C.

25. The method of electrodepositing a zinc coating on a substrate which comprises electroplating said substrate in an aqueous acidic bath which comprises zinc ions, and an amount, sufficient to provide a level zinc electrodeposit, of one or more bath-soluble leveling phosphorus cations having the formula:

R.sub.4 P.sup. .sym.

wherein each R is independently a hydroxy alkyl group.

26. The method of claim 25 wherein each R is the hydroxy methyl group.

27. The method of claim 25 wherein the bath also contains at least one nitrogen-containing compound obtained by reacting (a) ammonia, an aliphatic amine containing at least one primary amine group, or mixtures of two or more of any of these with (b) one or more epihalohydrins, glycerol halohydrins, or mixtures thereof.

28. The method of claim 27 wherein the nitrogen-containing compound is obtained by reacting ammonia with epichlorohydrin.

29. The method of claim 28 wherein the molar ratio of ammonia and epichlorohydrin is at least about 2:1.

30. The method of claim 29 wherein the ammonia and epichlorohydrin are reacted in the presence of water at a temperature below about 60.degree. C.

31. The method of claim 27 wherein the nitrogen-containing compound is obtained by reacting ethylene diamine with epichlorohydrin.

32. The method of claim 31 wherein the molar ratio of ethylene diamine and epichlorohydrin is at least about 1:1.

33. The method of claim 32 wherein the ethylene diamine and epichlorohydrin are reacted in the presence of water at a temperature below about 60.degree. C.

34. The method of claim 27 also containing at least one thiourea having the general formula:

[R'.sub.2 N].sub.2 CS

wherein each R' is independently hydrogen or an alkyl or alkenyl group.

35. The method of claim 26 wherein R' is hydrogen.

36. The method of claim 27 wherein (a) and (b) are reacted in the presence of water at a temperature below about 60.degree. C.

37. The method of electrodepositing a zinc coating on a substrate which comprises electroplating the substrate in an aqueous acidic bath which comprises zine ions and an amount, sufficient to provide a level zinc electrodeposit, of one or more bath-soluble phosphorus cations having the general formula:

[R"(CH(OH)].sub.4 P.sup..sym.

wherein each R" is independently hydrogen or a lower alkyl group.

38. The method of claim 37 wherein R" is hydrogen.

39. The method of claim 38 wherein the bath contains from about 0.1 to about four grams of the phosphorus cation per liter of bath.

40. The method of claim 37 wherein the bath also contains at least one nitrogen-containing compound obtained by reacting (a) ammonia, an aliphatic amine containing at least one primary amine group or mixtures of two or more of any of these, with (b) one or more epihalohydrins, glycerol halohydrins, or mixtures thereof.

41. The method of claim 40 wherein the nitrogen-containing compound is obtained by reacting ammonia with epichlorohydrin.

42. The method of claim 41 wherein the molar ratio of ammonia and epichlorohydrin is about at least 2:1.

43. The method of claim 42 wherein the ammonia and epichlorohydrin are reacted in the presence of water at a temperature below about 60.degree. C.

44. The method of claim 40 wherein the nitrogen-containing compound is obtained by reacting ethylene diamine with epichlorohydrin.

45. The method of claim 44 wherein the molar ratio of ethylene diamine and epichlorohydrin is at least about 1:1.

46. The method of claim 45 wherein the ethylene diamine and epichlorohydrin are reacted in the presence of water at a temperature below about 60.degree. C.

47. The method of claim 40 also containing at least one thiourea having the general formula:

[R'.sub.2 N].sub.2 CS

wherein each R' is independently hydrogen, an alkyl, or an alkenyl group.

48. The method of claim 47 wherein R' is hydrogen.

49. The method of claim 40 wherein (a) and (b) are reacted in the presence of water at a temperature below about 60.degree. C.

50. An additive composition for an aqueous acidic zinc electroplating bath comprising a mixture of

a. one or more bath-soluble phosphorus cations having the formula

R.sub.4 P.sup. .sym.

wherein each R is independently a hydroxy alkyl group, and

b. at least one thiourea having the formula

[R'.sub.2 N].sub.2 CS

wherein each R' is independently hydrogen or an alkyl or alkenyl group.

51. The additive composition of claim 50 wherein R is [R"CHOH] wherein R" is hydrogen or a lower alkyl group.

52. The additive composition of claim 51 wherein R" is hydrogen.

53. The additive composition of claim 50 wherein R' is hydrogen.

54. The additive composition of claim 50 wherein the mixture also contains (c) at least one nitrogen-containing compound obtained by reacting ammonia with one or more epihalohydrins, glycerol halohydrins, or mixtures thereof.

55. The additive composition of claim 54 wherein the nitrogen-containing compound is obtained by reacting ammonia with epichlorohydrin in a molar ratio of at least 2:1.

56. The additive composition of claim 55 wherein the nitrogen-containing compound is obtained by reacting ammonia with epichlorohydrin in the presence of water at a temperature below about 60.degree. C.

57. The additive composition of claim 54 wherein the nitrogen-containing compound is obtained by reacting ammonia with one or more epichlorohydrins, glycerol halohydrins, or mixtures thereof in the presence of water at a temperature below about 60.degree. C.

58. An additive composition for an aqueous acidic zinc electroplating bath comprising a mixture of

a. one or more bath-soluble phosphorus cations having the formula

R.sub.4 P.sup. .sym.

wherein each R is independently a hydroxy alkyl group, and

b. at least one nitrogen-containing compound obtained by reacting

i. ammonia, an aliphatic amine containing at least one primary amine group, or mixtures of two or more of any of these with

ii. one or more epihalohydrins, glycerol halohydrins or mixtures thereof.

59. The additive composition of claim 58 wherein R is [R"CHOH] wherein R" is hydrogen or a lower alkyl group.

60. The additive composition of claim 59 wherein R" is hydrogen.

61. The additive composition of claim 58 wherein the nitrogen-containing compound is obtained by reacting ammonia with epichlorohydrin in a molar ratio of at least about 2:1.

62. The additive composition of claim 61 wherein the nigrogen-containing compound is obtained by reacting ammonia with epichlorohydrin in the presence of water at a temperature below about 60.degree. C.

63. The additive composition of claim 58 wherein the nitrogen-containing compound is obtained by reacting ethylene diamine with epichlorohydrin.

64. The additive composition of claim 63 wherein the molar ratio of ethylene diamine and epichlorohydrin is at least about 1:1.

65. The additive composition of claim 64 wherein the ethylene diamine and epichlorohydrin are reacted in the presence of water at a temperature below about 60.degree. C.

66. The additive composition of claim 58 wherein the nitrogen-containing compound (b) is obtained by reacting (i) and (ii) in the presence of water at a temperature below about 60.degree. C.
Other info:

Inventors: Huebner, Karen (Parma, OH, US)

Application Number: 752079
Filing Date: 1976-12-20
Publication_date: 1978-02-28
Assignee: R. O. Hull & Company, Inc. (Cleveland, OH)
Primary Class(es): 205/313 205/311, 987/110
Other Classes:
US Patent Ref:

3884774

May, 1975

Kessler

204/55.

Other Refs:
Primary Examiner: Kaplan, G. L.
Assistant Examiner:
Attorney: Boisselle; Armand P.