US3634210A - Alkaline nickel plating solutions - Google Patents

Abstract

Addition agents for use in alkaline nickel plating baths which produce a brighter more ductile nickel electroplate. The addition agents are selected from the group consisting of substituted alkyl sulfonates wherein the alkyl radical contains from one-five carbon atoms and the substituents are selected from the group consisting of halogen, cyano and nitro.

Description

nited States Patent lnventors Arthur H. Du Rose Richmond Heights; Robert L. Stern, Cleveland Heights, both of Ohio Appl. No. 752,170 Filed Aug. 13, 1968 Patented Jan. 11, 1972 Assignee Kewanee Oil Company Bryn Mawr, Pa.

ALKALINE NICKEL PLATING SOLUTIONS 2 Claims, No Drawings [56] References Cited UNITED STATES PATENTS 2,937,978 5/l960 Strauss et al 204/49 3,417,005 l2/l968 Baig 204/49 X 3,428,536 2/1969 Towle et al. 204/49 Primary Examiner-G. L. Kaplan Attorney-John P. Hazzard ABSTRACT: Addition agents for use in alkaline nickel plating baths which produce a brighter more ductile nickel electroplate. The addition agents are selected from the group consisting of substituted alkyl sulfonates wherein the alkyl radical contains from one-five carbon atoms and the substituents are selected from the group consisting of halogen, cyano and nitro.

This invention relates to the electrodeposition of nickel and nickel-cobalt alloys from alkaline plating solutions containing a variety of addition agents which includes certain substituted alkyl sulfonates. More specifically, this invention is concerned with improving the brightness of nickel deposits produced from alkaline baths and increasing the limiting current density of said baths.

Alkaline nickel plating solutions have inherent advantages. The throwing power of such solutions is almost invariably better than that observed in acid nickel solutions of the Watts or all-chloride variety. For example, the throwing power for alkaline nickel solutions using the BS] formula ranges from to 70 percent while that for the Watts solution is 5 to +5 percent. Moreover, when proper preplating steps are followed, a number of alkaline nickel formulations can be used to plate nickel directly on zinc base die castings. This provides a distinct economic advantage as it avoids the need for the use of cyanide copper which not only eliminates the costly problem of waste disposal but affords a better corrosion resistance.

Many complex alkaline nickel plating solutions of various formulations have been proposed and devised heretofore. Their use, however, has not been extensive for several reasons, primarily because of a limited current density, lack of ductility, high stress and lack of luster in the deposit.

A variety of complexing agents has been used, see Saubestre's review in Plating, May 1958. Complexing agents which have been used singly or in combination with others are: NH OH (Brit. Pat. No. 512,484), triethanolamine as described in .I Met. Fin. Soc. Japan 11 (2) 55 (1960), citrate (Brit. Pat. No. 880,786), hydroxyethylethylenediaminetriacetic acid (Brit. Pat. No. 1,022,073), and polyamines (U.S. Pat. No. 2,335,070). Also ammonia, citrate and pyrophosphate are used in combination as described in U.S. Pat. No. 2,069,566 and Brit. Pat. No. 902,499. Similarly citrate, alkanolamines and EDTA-type compounds are described in U.S. Pat. No. 2,773,818.

Other complexing agents such as glycolic acid, tartarate, acetylacetone, and ethylenediamine may be used. Even glycerol and oxalate can be used although they are used in combination with other agents having more complexing ability and solubility.

Little work has been done on producing bright or semibright nickel deposits from alkaline solutions. Brit. Pat. No. 902,499 proposes the use of saccharin in combination with selenium, tellurium, arsenic or coumarin, while Brit. Pat. No. 880,786 uses saccharin and a rather high concentration of formaldehyde.

At first thought one might assume that any addition agent or brightener that is useful in acid nickel plating solutions would be also useful and effective in alkaline nickel solutions. This assumption has been shown many times not to be true. In fact many brighteners and addition agents which are effective in acid baths of zinc, tin, antimony copper and lead are ineffective and useless in the corresponding alkaline baths. Nickel is no exception. Table l is a list of compounds which exhibit little or no effect in alkaline nickel solutions.

TABLE I Phenylpropiolic acid (propiolic good) J-Methoxy-Il-phenyl butyne-l N-Propnrgyldlbcnzenesultonamidc Z-Propynyl) thiohenzothiazole Allylsulfonute Diallyl allyl phosphonatc Allylarsonic acid B-Neopentylallyl alcohol 4-Mcthyl-4-pentene-2-ol Undecyl-lO ene-l-ol Methylbuteneol Trinllylarnine Tetraallylethylenediamine N Allyl saccharin Cinnamyl alcohol Crotonic acid 17. Butanediol l8. Glycerine l9. Cyclohexunol 20. Fuchsin 21. Phenol 22. Nitroindazolc 23. Tetrnmethylene-bis-pyridinium chloride 24. Benzene sulfinic acid 25. Thiourea 26. Polyglycols and Pluronics It should be noted that compounds 1-7, 12-14, -26 of above table are useful in acid nickel baths.

An important difference between the alkaline and acid nickel solutions is that there appears to be very little, or consistent synergistic effect due to the combination of so-called acid nickel control agents and brighteners when they are used in combination in the alkaline nickel solution. in acid nickel solutions the use of the brightener alone (Such as fuchsin, ethoxylated propargyl alcohol, ethylenecyanohydrin, etc.) usually gives only a slight increase in or uneven deposit brightness and the deposit tends to be brittle. When a control agent such as naphthalene sulfonate or saccharin is added the brightness and uniformity of brightness are enhanced and the ductility is improved. Very seldom is the above combination of any benefit in the alkaline nickel solution. For example ethoxylated butynediol at 0.2 g./l. gives a bright deposit up to about 70 a.s.f. At higher current densities the deposit becomes duller. By acid nickel standards the ductility is poor. When 1 g./l. of saccharin is added the deposit becomes duller especially in the low-current density area and slightly less ductile. A similar effect, i.e., no improvement, is noted when 3 g./ 1. of N,N-bis-(phenylsulfonyl)-4,4-biphenyldisulfonimide is added to an alkaline nickel solution containing butynediol. Tetramethylene-bis-pyridinium chloride effects a streaked, semibright, very brittle deposit. The addition of N,N-bis- (phenylsulfonyl-4,4-biphenylenyldisulfonimide seemed to relieve the brittleness somewhat but darkened the deposit. N- Propargyl saccharin effects a bright deposit at 0.1 g./l. with air agitation and the addition of N,N'-bis(phenylsulfonyl)-4,4- biphenyldisulfonimide causes no improvement in ductility or brightness. For some reason N -allyl saccharin which is similar to N-propargyl saccharin when used in the acid bath, has no efiect when used in the alkaline solution.

In many cases as indicated above the addition of the sulfonate or sulfonamide control agent was harmful or of no help. In one case using 3 cc./1. of allyl alcohol the deposit was semibright but the addition of a sulfonamide increased the brightness. This was not so for B-chloroallyl alcohol where only 0.5 cc./l. of the alcohol had to be used. The use of N ,N'- bis(phenylsulfonyl)-4,4'-biphenyldisulfonimide will eliminate misplating caused by high concentrations of ethoxylated propargyl alcohol but just as good deposits are obtained when lower concentrations of the acetylenic compound are used with no sulfonimide. Another case where a control agent was beneficial was for Z-butyne-l,4,-dithioethanol. These cases are rare however.

The use of certain sulfonate and sulfonamide control agents alone, in alkaline nickel solutions-has little effect compared to when these are used in acid solutions. The deposit from alkaline solutions with no addition agents present usually has more sheen than those from acid solutions. This may be why the addition of such agents as benzene sulfonate, saccharin or allyl sulfonate very seldom exhibit any improvement in brightness. Sometimes, as for dibenzenesulfonamide the uniformity of lustre is improved but the increase in luster is almost negligible. Also the ductility is not improved.

The addition agents of the present invention comprise substituted alkyl sulfonates wherein the alkyl radical contains from one to five carbon atoms and the substituents are selected from the group consisting of halogen, cyano and nitro. The effective concentration range for these addition agents of the instant invention is from 0.1 to 5.0 g./l. while the optimum concentration appears to be about 2 'g./l. for these compounds. One way in which these materials may be supplied to the electroplating bath of the instant invention is to supply them in the form of the sodium salt, although the sulfonate of the instant invention can be supplied in any other manner familiar to those skilled in the art and the need not necessarily be the sodium salt thereof.

These addition agents of the instant invention are utilized to advantage in alkaline nickel plating processes. Such a nickel plating process can utilize any conventional source of nickel as used in the plating industry such as NiC1 NiSo nickel sulfamate or NiBF wherein the pH is adjusted to between about 7.0 and l 1.0. Such plating baths can be operated generally in the range from room temperature to 180 F. depending on the particular-type bath employed. Likewise, plating can be accomplished in such baths at current densities of from about 5 to about 100 amps per sq. ft.

Typical compounds falling within the scope of the instant invention and their effective concentration ranges as well as optimum concentrations are given hereinafter.

6. 2,3-diiodopropylsull'onntc 0.l5.0 2.0

1 (I)CH cH, so,, Na

7. Z-chlorocthylsulfonate 0.1-5.0 10

ci-cH,-cH, -s0, Na

8. Z-Cynnoethancsulfonalc 0.1-5.0 2.0

As stated earlier in the specification, any conventional source of nickel may be used in supplying the nickel for the plating bath for the instant invention. For example, nickel chlorate, nickel sulfate, nickel tetraborate, nickel carbonate. nickel hydroxide, nickel sulfamate and the like. Commonly complexing agents are used in such plating baths to produce complex ions and such is suitable in the practice of the instant invention.

We claim:

1. A nickel electroplating bath comprising an aqueous alkaline solution having a pH of between about 7.0 and about 1 1.0 including at least one electrolyte containing nickel ions and having dissolved therein a sufficient amount of a single brightening agent consisting of between about 0.1 and 5.0 g./l. of a substituted alkyl sulfonate wherein the alkyl radical contains from one to five carbon atoms and the substituents are selected from the group consisting of halogen, cyano and mtro.

2. The bath of claim 1 wherein 3-cyano-propanesulfonate is the brightening agent, and is used in an amount of between the about 0.1 and about 5.0 g./l.

Claims (1)

1. 2. The bath of claim 1 wherein 3-cyano-propanesulfonate is the brightening agent, and is used in an amount of between the about 0.1 and about 5.0 g./1.