US3709798A - Electrodeposition of nickel - Google Patents

Abstract

AN AQUEOUS ACIDIC BATH SOLUTION FOR ELECTROPLATING NICKEL INCLUDES AT LEAST ONE NICKEL SALT AS A SOURCE OF NICKEL AND, AS A BRIGHTENER, A COMBINATION OF AN OXYETHYLENATED SULFOLENE COMPOUND AND A WATER-SOLUBLE ALLYL SULFONATE IN AN AMOUNT SUFFICIENT TO PRODUCE A BRIGHT NICKEL ELECTRODEPOSIT.

Description

United States Patent 3,709,798 ELECTRODEPOSITION 0F NICKEL Joseph R. Duchene, Southfield, Mich., assiguor to The Richardson Chemical Company, Baltimore, Md.

N 0 Drawing. Continuation-impart of application Ser. No. 52,083, July 2, 1970. This application Oct. 13, 1971, Ser. No. 188,771

Int. Cl. C23b 5/08 US. Cl. 20449 3 Claims ABSTRACT OF THE DISCLOSURE An aqueous acidic bath solution for electroplating nickel includes at least one nickel salt as a source of nickel and, as a brightener, a combination of an oxyethylenated sulfolene compound and a water-soluble allyl sulfonate in an amount sufficient to produce a bright nickel electrodeposit.

This application is a continuation-in-part of my application S.N. 52,083, filed July 2, 1970.

This invention relates to the electrodeposition of nickel and more particularly to electroplating solutions adapted to produce full bright nickel deposits. The bright nickel deposit produced according to this invention exhibits improved ductility and throwing or covering characteristics and thus is capable of improved coverage of imperfections in the base metal.

It has now been found that improved full bright, ductile nickel deposits can be obtained using an aqueous acidic nickel plating bath having incorporated therein a brightening system comprising a combination of an oxyethylenated sulfolene compound and a water-soluble allyl sulfonate.

It has been known to modify nickel electroplating baths with brightening agents as well as with agents to improve leveling effects. The use of nickel plating baths containing a sulfolene compound, such as sulfolanyl ether as a brightening agent is disclosed for instance in US. Pat. 3,376,207. It was found, however, that in order to obtain a full bright nickel deposit to the degree desired, the said sulfolene compounds of this reference, for instance, hydroxy butyne sulfolanyl ether, had to be modified by the addition thereto of nitrogen or a nitrogen type brightener, such as an imidizol, and an aromatic carrier such as sodium saccharin or 1,3,6-naphthalene trisulfonic acid, sodium salt to obtain a full bright nickel deposit. However, the addition of these materials often produced deleterious effects with respect to the ductility and hardness of the subsequent nickel deposit. The breakdown products of nitrogen bearing compounds can be particularly deleterious, causing stresses in the subsequent nickel deposit. Accordingly, where ductility and hardness are desirable or the necessary characteristics, the use of such combinations of materials in the plating bath did not appear advisable.

It was then found that such disadvantages could be overcome by including in the aqueous acidic nickel plating bath a brightening agent consisting essentially of a sulfolene compound in combination with a watersoluble allyl sulfonate as disclosed in my copending application S.N. 52,083. It was also found that this combination of materials, i.e. the sulfolene compound and the water-soluble allyl sulfonate exhibited a synergistic effect and that this combination produced superior nickel electrodeposits when compared, for instance, to earlier known additives. Additionally, it was found that the novel plating baths disclosed in my aforementioned application also provided desirable results in the absence 3,709,798 Patented Jan. 9, 1973 of any conventional nitrogen containing compounds and any aromatic sulfur compounds.

As an improvement on the invention disclosed in S.N. 52,083 there is now provided a novel plating bath which includes as a brightening agent an oxyethylenated sulfolene compound in combination with a water-soluble allyl snlfonate. This combination of components provides an even higher luster to the resulting nickel deposit and the brightener itself exhibits markedly improved stability characteristics. The preferred brightening agent system employed in the present invention is the reaction product of 3-sulfolene with 1,4-di-(2-hydroxyethoxy) butyne-2, or 2-butyne 1,4 diol oxyethylenated with 2 mols of ethylene oxide in combination with sodium allyl sulfonate, although, as the oxyethylenated sulfolene compound the following materials can also be usefully employed: the reaction product of 3-sulfolene with a member selected from the group consisting of propargyl alcohol, Z-butyne- 1-ol, 4-methoxy-2-butyne-1-ol, 3-hexyne-2,5-diol, 3-pentyene-l-ol and 2,4-hexadiyne-1,6-diol, said member being oxethylenated with 2 moles of ethylene oxide.

The novel brightening agent of this invention is generally used in the amounts between 1.5 to 5 grams of sodium allyl sulfonate per liter of bath solution and 0.01 to 1.0 gram of the oxyethylenated sulfolene compound per liter of bath solution.

In general, the process of this invention involves operating a bath at conventional nickel plating temperatures ranging from about room to boiling, though usually most convenient temperatures of operation are from about F. to 170 F. The best pH values for the bath range from about 3.5 to 4.5 though a pH as low as 2 and as high as 6 can also be employed. Preferably, the pH will range between 3.0 and 5.0 in the majority of the cases. The cathodic current densities to be used average generally from about 1 to 200 amp/sq. ft. depending, for instance, on the temperature, degree of solution agitation and the composition of the bath. Higher temperatures and more rapid agitation permit higher current densities to be used effectively.

Baths for electroplating in accordance with this invention contain at least one nickel salt as a source of nickel and include well-known Watts-type bath and high chloride type bath. The Watts bath solution typically comprises around 200'400 grams/liter of nickel sulfate, 30- 75 grams/liter of nickel chloride and 3050 grams/liter of boric acid. A high chloride type bath can contain about -300 grams/liter of nickel chloride, 40-150 grams/liter of nickel sulfate and 3050 grams/liter of boric acid. Considerable latitude is also permissible in respect to the types and concentrations of the nickel salts employed. For instance, as the source of nickel, nickel sulfamate as well as a combination of nickel fluoborate with nickel sulfate and nickel chloride or a combination of nickel fiuoborate with nickel chloride can be employed.

Additionally, the bath can include other brighteners. However, such other brighteners are not necessary to obtain the full bright, ductile nickel deposits of this invention. Examples of other brighteners which can be used in addition to the novel brighteners of this invention include aliphatic sulfur compounds such as methallyl sulfonate, 2-butene, l-chloro, 4-sulfonate and Z-butene, 1,4- disulfonic acid. Generally, when used, such aliphatic sulfur compounds can be present in amounts ranging from 0.1 to 10 grams/liter of solution.

Additionally, water-soluble acetylenic compounds can also be effectively included in the bath solution of this invention. The acetylenic compounds include 2-butyne-1, 4-diol, 4-methoxy-2-butyn-1-ol, 3-hexyne-2, S-diol, 3- pentyn-l-ol, 2,4-hexadiyne-1, 6-diol. Conveniently, the

water-soluble acetylenic compound can be employed in amounts ranging from about 0.01 to 0.03 gram/liter of solution.

For the purpose of giving those skilled in the art a better understanding of the invention, the following illustrative examples are given in which the aqueous acidic nickelcontaining bath was made up with specified components. Electrodeposition was carried out by passing electric current through an electric circuit comprising an anode and a sheet metal or rod cathode, both immersed in the bath. The bath was agitated, usually by moving the cathode although, in certain instances, air agitation or other mechanical or electrical agitation means can be employed.

In the examples, the below described standard Watts-type bath was used as a base solution and a standard 267 ml. hull cell was used as the plating cell:

Nickel sulfate, 02/ gal. 40 Nickel chloride, oz./ gal 8 Boric acid, oz./ gal 6 pH 4.0-4.2 Temperature, F 140 Current, amperes 2 Time, min l Agitation, strokes/min. 4050 To illustrate the synergistic efiect of the combination of the oxyethylenated sulfolene compound and water-soluble allyl sulfonate, Examples 13 below are provided.

EXAMPLE 1 G./l. Reaction product of 3-su1folene and 2-butyne 1,4-diol oxyethylenated with 2 moles ethylene oxide 0.05

EXAMPLE 2 G./l. Sodium allyl sulfonate 3 EXAMPLE 3 G./l. Reaction product otf 3-sulfolene and Z-butyne 1,4-diol oxyethylenated with 2 moles ethylene oxide 0.05 Sodium allyl sulfonate 3 Steel panels, nickel plated with the respective baths defined above, exhibited, only in the case where both an oxyethylenated sulfolene compound and a water-soluble allyl sulfonate were used, i.e. Example 3, a full bright, level and ductile electrodeposit over the whole current density range. The electrodeposits resulting from both Examples 1 and 2 were significantly inferior with respect, for instance, to the brightening characteristics achieved with the brightening agent employed in Example 3.

Examples 4-6 and 89 illustrate that the advantages of the present invention also are not achieved when the ingredients making up the combination of materials of this invention are used, singly or in combination, with conventionally employed nitrogen bearing or aromatic sultfur containing brightening agents or when these conventional brightening agents are employed alone. Examples 4-6 and 810 when compared to Example 7 or Example 3 which employ the brightening agent of this invention, fail to provide the advantages attained by the present invention.

EXAMPLE 4 Saccharin 1 EXAMPLE 5 Reaction product of 3-sulfolene with 2-butyne 1,4-

diol oxyethylenate with 2 moles ethylene oxide 0.05

Saccharin 1 EXAMPLE 6 Sodium allyl sulfonate 3 Saccharin 1 4 EXAMPLE 7 G./l. Reaction product of 3-sulfolene with Z-butyne 1,4-

diol oxyethylenated with 2 moles ethylene oxide 0.05

Sodium allyl sulfonate 3 Saccharin 1 EXAMPLE 8 1,3,6-napl1thalene trisulfonic acid, sodium salt 4 EXAMPLE 9 1,3,6-naphthalene trisultfonic acid, sodium salt 4 Reaction product of 3-sulfolene with Z-butyne 1,4-

diol oxyethylenated with 2 moles ethylene oxide 0.05

EXAMPLE l0 G./l. 1,3,6-naphthalene trisulfonic acid, sodium salt 4 Reaction product of 3-sulfolene with 2-butyne 1,4-

diol oxyethylenated with 2 moles ethylene oxide 0.05 Sodium allyl sulfonate 3 Examples 11-18 are provided to illustrate the use of oxyethylenated sulfolene compounds other than that obtained by the reaction of 3-sulfolene with 2-butyne 1,4-diol oxyethylenated with 2 moles ethylene oxide in combination with sodium allyl sulfonate and to illustrate varying proportions of each while still achieving the desired results of the present invention.

EXAMPLE 11 G./l. Reaction product of 3-sulfolene with 2 butene-1,4-

diol oxyethylenated with 2 moles ethylene oxide 0.05 Sodium allyl sulfonate 1.5

EXAMPLE 12 G./1. Reaction product of 3-sulfolene with propargyl alcohol oxyethylenated with 2 moles ethylene oxide 0.03

EXAMPLE l3 G./l. Reaction product of 3-sulfolene with 2-butyne-l-ol oxyethylenated with 2 moles ethylene oxide 0.05 Sodium allyl sulfonate 3 EXAMPLE 14 G./l. Reaction product of 3-sulfolene with 4-methoxy 2-butyne-1-ol oxyethylenated with 2 moles ethylene oxide 0.1 Sodium allyl sulfonate 3 EXAMPLE 1S Reaction product of 3-sulfolene with 3-hexyne-2,5-

diol oxyethylenated with 2 moles ethylene oxide 0.01

Sodium allyl sulfonate 1.5

EXAMPLE l6 G./l. Reaction product of 3-sulfolene with 3-pentyne-1-Ol oxyethylenated with 2 moles ethylene oxide 0.01 Sodium allyl sulfonate 5 EXAMPLE 17 G./l. Reaction product of 3-sulfolene with 2,4-hexadiyne- 1,6-diol oxyethylenated with 2 moles ethylene oxide 1 Sodium allyl sulfonate 1.5

Unless otherwise specified, all parts and percentages in the specification and claims are by weight. The foregoing examples illustrate specific baths and processes, several being preferred. It is to be understood that the compositions and conditions can be varied. For instance,

other aqueous acidic bath solutions can be used in place of the Watts-type bath mentioned above. For example, substantially equally favorable results can be attained using a virging sulfamate nickel bath instead of the Watts bath specified above.

What is claimed is:

1. An aqueous acidic electroplating bath solution for producing a bright nickel deposit consisting essentially of at least one nickel salt as a source of nickel and, as a brightener, a combination of an oxyethylenated sulfolene compound which is the reaction product of 3- sulfolene with a member selected from the group consisting of Z-butyne 1,4-diol, 2-butyne-1-ol, 4-methoxy-2 butyne-l-ol, 3-hexyne-2,5-diol, 3-pentyne-1-ol and 2,4- hexadiyne-1,6-diol, said member being oxyethyleuated with 2 moles of ethylene oxide and a water-soluble allyl sulfonate wherein the oxyethylenated sulfolene compound is present in amounts from 0.01 to 1.0 g./l. and the water-soluble allyl sulfonate is present in amounts from 1.5 to 5 g./l.

2. The electroplating bath of claim 1 wherein the oxyethylenated sulfolene compound is the reaction product References Cited UNITED STATES PATENTS 2,550,449 4/ 1951 Brown 20449 3,334,032 8/1967 Kardos 20449 3,376,207 4/1968 Ericson 20449 3,399,123 8/1968 Passel 20449 3,413,295 11/1968 Passel et a1. 20449 3,639,220 2/1972 Fuchs et al. 20449 F. C. EDMUNDSON, Primary Examiner U.S. Cl. X.R. 204Dig. 2