US3002903A - Electrodeposition of nickel - Google Patents

Description

United States Patent 3,002,903 ELECTRODEPOSITION 0F NICKEL Donald Gardner Foulke, Watchung, Otto Kardos, Red Bank, and Herman Koretzky, Bellcville, N.J., assignors to Hanson-Van Winkle-Munning Company, a corporation of New Jersey No Drawing; Filed Sept. 26, 1958, Ser. No. 763,455

12 Claims. (Cl. 204-49) This invention relates to electroplating and, more particularly, to electrodepositing nickel from an aqueous acidic nickel plating bath. The invention is based on the discovery that water-soluble bisulfite addition products of acetylenic compounds, when incorporated in a nickel electroplating bath, particularly in conjunction with various sulfo-oxygen compounds, are capable of promoting the formation of excellent bright and ductile electrodeposits of nickel over a wide current density range.

The electrodeposition of nickel from a plating bath containing a sulfo-aoxygen carrier brightener additive generally produces a semi-bright deposit at the cathode, particularly at the lower current densities. Increasing the current density frequently increases the overall brightness of the deposit, but often induces the formation of cloudy or hazy areas, especially at the low and middle current density ranges. When, however, a small quantity of the bisulfite addition product of an acetylenic compound is incorporated in the plating bath together with a sulfo-oxygen compound, the brightness capacity of the bath is extended, and the electrodeposit is ductile and bright over a very wide current density range.

Theoretically, there are at least two possible bisulfite addition products which may be formed from a given acetylenic compound. Disregarding the numerous optical and geometrical enantiomorphs which chemical theory predicts may be formed, the addition of a bisulfite to an acetylenic bond proceeds in two successive stages, the first of which results in the formation of an initial bisulfite addition product which, in turn, reacts in the second stage to produce a second bisulfite adduct. The extent of the reaction is dependent upon and therefore controlled by the molar proportions of bisulfite present in the reaction mixture. Although the proof of structure of each of the two adducts is far from conclusive, the initial bisulfite addition product of an acetylenic compound appears to be an a,B-unsaturated sulfonic acid (or sulfonate) which is capable of undergoing further addi tion, in the presence of excess bisulfite, to form the second adduct. The apparent structure of this second bisulfite addition product is that of a saturated disulfonic acid (or disulfonate), in which the sulfonic acid (or sulfonate) groups are vicinal.

Because almost any acetylenic compound can be made to undergo bisulfite addition, that is can be made to react with a compound capable of forming a chain-carrying sulfite radical to form one or more bisulfite addition products, no single common structural feature can be advanced to unequivocally characterize all of these adducts. Instead, the adducts may conveniently be characterized by designating the proportionate amount of bisulfite (or.

of any compound capable of forming a chain-carrying sulfite radical) used in the reaction mixture.

Following an exhaustive investigation into the chemistry of bisulfite addition to acetylenic bonds, it has been found that the bisulfite addition products prepared by reacting a water-soluble acetylenic compound together with N times an equivalent weight of a compound capable of forming a chain-carrying sulfite radical, where N is equal to the number of acetylenic bonds per molecule of the acetylenic compound, are unusually effective for promoting the formation of bright and even brilliant electrodeposits of nickel over a very wide current density 3,002,903 Patented Oct. 3, 1951 "ice range when the bisulfite adduct is incorporated in an aqueous acidic nickel plating bath which also contains one or more sulfo-oxygen carrier brightener compounds. Moreover, the combined use of the sulfo-oxygen compound and the bisulfite addition product has been found to exert a synergistic effect on the brightening capacity of the bath as compared with the use of either additive a one.

Only very small quantities of the bisulfite adducts are required in the plating bath and, generally, concentrations as low as 0.1 millimole per liter are effective. In many cases, however, at least 1 millimole per liter of the bisulfite adducts should be employed to secure the full benefit of their presence in the bath. There appears to be no sharply delineated upper limit on the concentration of these, bisulfite addition products, but there is generally no advantage in employing more than 100 millimoles per liter, and in most plating baths substantially full benefit of its presence is achieved with 20 millimoles per liter, or even less.

Any bisulfite addition product prepared by reacting a Water-soluble acetylenic compound with N times an equivalent weight of a compound capable of forming a chaincarrying sulfite radical, where N is equal to the number of acetylenic bonds per molecule of the acetylenic compound, and which is capable of being dissolved in acid and does not undergo decomposition upon protonation may be selected for inclusion in the plating solution. Particularly satisfactory results have been obtained by using thebisulfite adducts prepared from a-substituted or a,a-disubstituted acetylenic compounds, both of Which contain a functional group on a carbon atom vicinal to the acetylenic bond. It is of course necessary that the a.- substituted or a,a'-disubstituted acetylenic compounds used to prepare the bisulfite adduct contains at least one acetylenic bond which is neither sterically nor electronically hindered from reacting with a chain-carrying sulfite radical.

A preferred process according to this invention for producing bright nickel deposits comprises electrodepositing nickel from an aqueous acidic solution of at least one nickel salt in which there is dissolved from M; to grams per liter of a sulfo-oxygen carrier brightener together with from about 1 to about 25 millimoles per liter of the bisulfite addition product of an inc-substituted acetylenic compound and N times an equivalent weight of a compound capable of forming a chain-carrying sulfite radical, N being equal to the number of acetylenic bonds per moleclue of the acetylenic compound. The u-substituted acetylenic compounds used in preparing this bisulfite adduct all contain the structural configuration GEC :3

Rn in which R, is a substituent of the group consisting of hydrogen, alkoxy, formoxy, alkanoxy, halogen, and polyoxy groups having the structure 30 -O[OH )H0]nH in which R is a substituent of the group consisting of hydrogen, methyl, chloromethyl, hydroxymethyl, ethenyl, and glycidyl, and n is an integer from 1 to 20. In addition, R, may also be an amino group having the structure in which each of R and R" are either hydrogen, alkyl, or hydroxyalkyl. The synergistic effect of the bisulfite addition products prepared by these acetylenic compounds on the brightening capacity of various sulfo-oxygen compounds is especially pronounced when the bisulfite adducts are used in the nickel plating solution together with one or more of the water-soluble sulfo-oxygen compounds natively, the bisulfite addition product may be recovered from the reaction mixture (either by crystallization or prepicitation), and then added to the plating bath, the same plating results being obtained in either case Alselected from the group consisting of unsaturated ali- 5 though the bisulfite addition products may be used in phatic sulfonic acids, mononuclear and binuclear aromatic nickel plating baths in concentrations as high as 100 sulfonic acids, heterocyclic sulfonic acids, mononuclear millimoles per liter, or even more, there is no particular aromatic sulfinic acids, the alkali metal, ammonium, magadvantage to be gained from the higher concentrations, nesium, and nickel salts of these acids, and mononuclear and the adducts are preferably used in the range of conaromatic sulfonamides and sulfonimides. centrations from about 1 to about 25, or even in the Preparation of the bisulfite addition products is genrelatively narrow range from 1 to 10 millimoles per liter. erally accomplished by refluxing an aqueous solution The bisulfite addition products prepared from a-subcontaining both the acetylenic compound and an alkali stituted acetylenic compounds have been found to be unmetal bisulfite (or sulfite) until most of the bisulfite (or usually effective brightening agents, especially when used sulfite) ion has been consumed. The rate at which biin a plating bath in conjunction with various sulfo-oxysulfite ion is consumed in the reaction has been found gen compounds. Particularly satisfactory results have to be susceptible to catalysis by passing gaseous oxygen been obtained from the bisulfite addition products prethrough the reaction mixture or by adding a trace amount pared from tat-substituted acetylenic compounds having a of a free radical initiator (i.e., benzoyl peroxide) to the structure represented by the formula reactants; the rate is sharply diminished by adding trace amounts of free radical inhibitors, such as hydroquinone l and similar antioxidants, to the reaction mixture. From R C:G R1 these observations, it may be concluded that bisulfite ada fim to an q y f bond p f y by a radical in which each of R and R are substituents of the group chain process, 1n which the chain-carrying steps may be 5 consisting f hydrogen, k l lk 1k 1 and postulated as Proceedmg Vla the followmg reactlon droxy-substituted, alkoxy-substituted, and amino-substiquencei tuted alkyl, alkenyl, and alkynyl groups, and R is a sube stituent of the group consisting of hydrogen, halogen, alkyl, alkenyl, alkynyl, hydroxy-substituted, alkoxy-substis0i- -lCEO- O=O tuted, and amino-substituted alkenyl and alkynyl groups. e e In addition, R may also be a substituted-alkyl group having the structural configuration -o=o-+Hs0a -o=o.u+sos- 2 The exact nature of the chain-carrying sulfite radical is not actually known, since a similar chain involving HSO can be written. Both species (80 -6 and HSO have been proposed for the autoxidation of bisulfite and sulin wllich each of 4 and 5 are substituents 0f the group fite ions by oxygen, and hence either might plausibly conslsti'ng f hydrogen. y a y y yl. and y; function as the transitory intermediate which adds to the droxy-substltuted, alkoxy-substliuted, and ammo-Subsuacetylenic bond. No matter what the transitory interme- 40 fi y alkenyl, and y y p Each of a diate radical, however, any compound which is capable and h in above formulas are substituents 0f the group of forming a chain-carrying sulfite radical may be used consisting of Y Y; y, Y, alkafloxy, halo to form the bisulfite adduct. The term compound capagen and P Y Y groups having the structure ble of forming a chain-carrying sulfite radical denotes R0 the alkali metal or metal bisulfites, sulfites, and metabisulfites, as well as sulfurous acid or gaseous sulfur'dioxide. B n All of these compounds react with acetylenic compounds In Whlch R0 15 a substltuent of the group conslstmg of to form bisulfite adducts which, in turn, may be used in hydrogelb methyl, h m hyl, hydroXymethyl, ethenyl, nickel plating baths in accordance with this invention. and glycldyl and n 15 a merger m 1 to 8 and Even though all of the available evidence indicates Rb may also be an ammo group havmg the structure that bisulfite addition to acetylenic compounds is radical i R in nature, and that consequently the predominant prodnot formed is the corresponding conjugated sulfonic acid (or sulfonate), the possibility that bisulfite or sulfite ions form charge-transfer complexes with acetylenic bonds, or in which each of R and R"- are substituents of the group that bisulfite or sulfite ions undegro simple ionic addition Consisting of hydrogen, y and y y y The to an acetylenic bond, cannot be completely dismissed. compounds listed in Table I are examples of various a-sub- After the bisulfite adduct has been prepared, the reacstituted acetylenic compounds which may be used to pretion mixture may be added directly (or decolorized and pare bisulfite addition products which, in turn, may be then added directly) to the nickel plating bath or, alteremployed successfully in embodiments of this invention.

TABLE I tat-Substituted acetylenic compounds Compound R1 R; Ra a 3-butyne l,2-di0l I i HzOH 4-H H OH 3-methyl-1-butyu-3-ol --CH3 -on, H. -o11 3-methyl-1-pentyn-3-ol C,H5 OH; H -0H 2-propyn-1- -H V -H H ''-OH 2,S-dimethyI-I-o ten B-yn-E-Ol -o u1 --oH,' pm 0H 1 The bisulfite addition products of each of the acetylenic compounds listed in Tables I and H are prepared by refluxing an aqueous solution of the particular acetylenic compound with N times an equimolar proportion of a compound capable of forming a chain-carrying sulfite radical, preferably an alkali metal bisulfite, N being equal to the number of acetylenic bonds per molecule of the acetylenic compound. These adducts readily dissolve,

without decomposition, in aqueous acidic plating baths,

and are unusually effective in such bathsboth in'promoting the formation of bright and ductile nickel electrodeposits over wide current density ranges and in extending the brightening range of sulfo-oxygen carrier" brightener additives.

The compounds listed in Table III are examples of sulfo-oxygen compounds which, when used in the plating bath in conjunction with the bisulfite addition product of an acetylenic compound, extend the current density range over which the formation of ductile and bright nickel electrodeposits may be obtained. These sulfooxygen compounds may be used over a very wide range of concentrations to 80 grams per liter), but preferably are used in an amount in the range from about 1 to about 20 grams per liter.

TABLE 111 Organic sulfa-oxygen compounds (1) Unsaturated aliphatic sulfonic acids, and alkali metal, ammonium, magnesium, and nickel salts thereof:

Sodium vinyl sulfonate, H C=CHSO Na Sodium allyl sulfonate, H @CHCH SO Na (2) Mononuclear aromatic sulfonic acids, and alkali metal, ammonium, magnesium, and nickel salts thereof:

Benzene monosulfonic acid, C H SO H Sodium benzene monosulfonate, C H SO Na Nickel benzene monosulfonate, (C I-I SO Ni Sodium p-toluene monosulfonate, CH C H SO Na p-Chlorobenzene sulfonic acid, ClC H SO H Sodium p-chlorobenzene sulfonate, ClC H SO Na Sodium p-bromobenzene sulfonate, BrC H SO Na 1,2-dichlorobenzene sulfonic acid, Cl C H SO H 1,2- or 2,5-dichlorobenzene sulfonate sodium salt,

Cl C H SO Na Sodium m-benzene disulfonate, C H (SO Na) m-Benzene disulfonic acid, C H (SO H) Nickel m-benzene disulfonate, C H (SO Ni o-Sulfobenzoic acid monoammonium salt,

HOOC-C H SO NH 1-Amino-2,5-benzene disulfonic acid,

o-Aminobenzene sulfonic acid, H NC H SO H (3) Mononuclear aromatic sulfinic acids, and alkali metal, ammonium, magnesium, and nickel salts thereof:

Sodium benzene sulfinate, C H SO Na Sodium p-toluene sulfinate, CH C H SO Na (4) Mononuclear aromatic sulfonamides and sulfonimides:

Benzene sulfonamide, C H SO NH p-Toluene sulfonamide, CH C H SO NH o-Sulfobenzoic imide, C H CONHSO Benzyl sulfonamide, C H CH SO NH Benzene sulfhydroxamic acid, C H SO NHOH -N,N-dimethyl-p-toluene sulfonamide,

CH C H SO N(CH N,N-dicarboxyethyl benzene sulfonamide,

C H SO N(C H COOH) (5) Binuclear aromatic sulfonic acids, and alkali metal,

ammonium, magnesium, and nickel salts thereof: 2-naphthalene monosulfonic acid, C H- SO H 1,5- or 2,7-naphthalene,disu1fonic acid,

8 Nickel 1,5- or 2,7-naphthalene disulfonate,

Sodium naphthalene trisulfonate, C I-I (SO Na) Naphthalene trisulfonic acid, C H (SO H) Diphenyl p,p-disulfonic acid,

2-naphthol-3,6-disulfonic acid, HOC H (SO H) Sodium 2-naphthol-3,6-disulfonate,

1-naphthylamine-3,6,8-trisulfonic acid, 2 1o 4( 3 )s (6) Heterocyclic sulfonic acids, and alkali metal, am-

monium, magnesium, and nickel salts thereof:

Thiophene sulfonic acid, C H S-SO H Sodium thiophene sulfonate, C H S-SOgNa 2-(4-pyridyl)ethyl sulfonic acid, C H N-C H SO H For the most part, only the free sulfonic acids are listed in Table III. However, the alkali metal, ammonium, magnesium, and nickel salts of these acids are in all cases the full equivalent of the corresponding sulfonic acid, and may be used in its place in carrying out the process of the invention.

The following examples are illustrative of the effectiveness with which the bisulfite addition product of acetyleniccompounds may be used in conjunction with various sulfooxygen compounds in accordance with this invention. In each example, Watts nickel plating bath having the following basic composition was used:

Grams per liter Nickel sulfate, NiSO -7H O 300 Nickel chloride, NiCl -6H O 45 Boric acid, H 30 41.25

.Unless otherwise indicated, plating operations in each example were carried out in a Hull test cell on brass .cathodes so that the effect of a wide range of current densities could be observed. The pH of the bath was adjusted to 3.2 with sulfuric acid, and the electrodeposits Were formed at a temperature of 60 C. using a total current of 2 amperes and a plating time of about 10 minutes. The average thickness of each electrodeposit was 0.025 mm. (0.001 inch). No agitation was provided.

, In several of the examples, the electrodeposits were formed in an open vessel on polished steel cathodes, using vigorous air agitation and an average current density of 60 amperes per square foot and the same bath temperature and pH as previously indicated. The leveling effect exerted by the bath, which is a measure of the decrease in roughness 'of the nickel electrodeposit compared to that of the underlying metal surface, was calculated in each of these examples. To determine the leveling effect exerted by the bath the roughness value (root mean square value in microinches) of the steel panel was measured with a Brush Surface Analyzer prior to the plating operation. The roughness value of the plated panel was similarly measured immediately following the plating operation, and the leveling effect then calculated according to the following equation:

where L=leveling effect (percent); R =initial roughness value (R.M.S. value in microinches) of the steel panel; and R =final roughness value (R.M.S. value in microinches) of the nickel electrodeposit on the panel.

EXAMPLE I The bisulfite addition product of Z-butyne-lA-diolwa prepared by refluxing equimolar proportions of Z-butyne- 1,4-diol (in the form of a 36 percent aqueous solution) and sodium bisulfite. After refluxing the reaction mixture for about 7 /2 hours, it was diluted with water, treated with activated carbon and filtered, yielding a very light yellow solution. Titration of an aliquot of the filtrate with standard iodine-potassium iodide reagent, using starch as an indicator, showed that only 2.6 mole percent of the original sodium bisulfite had remained unreacted. From both the infrared spectrum and the chemical properties of the bisulfite addition product, it may be adduced that the predominant product formed during the reaction was sodium l,4-dihydroxy-Z-buteneZ-sulfonate. The bisulfite addition product could be used in nickel plating baths without further purification, or it could be precipitated or crystallized from solution and then redissolved in the plating bath, the plating results being the same in either case.

Table IV summarizes the results of a series of tests which demonstrate the brightening effect on the basic Watts plating bath of various concentrations of representative sulfo-oxygen compounds, alone and in combination with the bisulfite addition product of equimolar quantifies of 2-butyne-l,4-diol and sodium bis'ulfite described immediately above. The plating operations were carried out both in a Hull test cell on brass cathodes and in an open vessel on a steel panel which had been polished to give an initial surface roughness value of about microinches.

TABLE IV sulfite addition product exerted a pronounced leveling effect on the bath during the plating operation.

EXAMPLE III Equimolar proportions of 1,4-diacetoxy-2butyne and sodium bisulfite were dissolved in water and the solution refluxed for about 5 hours. The reaction mixture was diluted with water, decolorized with activated carbon, filtered under suction, and the filtrate used in the plating bath without turther purification.

When 4.4 millimoles per liter of bisulfite addition product were added to a Watts plating bath which had substantially the same composition (in nickel sulfate, nickel chloride, and boric acid) of Example I and which contained 3 grams per liter of sodium naphthalene-1,3,6- trisulfonate, the nickel deposit formed on the test panel of a Hull cell was very bright and ductile over the current density range of from 10 to 60 amperes per square foot. Increasing the concentration of the bisulfite adduct to 8.8 millimoles per liter did not substantially increase the brightness.

EXAMPLE IV To a dilute aqueous solution of l,4-di(;3-hydroxyethoxy) -2-butyne was added an equimolar quantity of sodium bisulfite and the reaction mixture refluxed for about 7 hours. After cooling, the solution was further diluted with water, treated with activated carbon, and filtered under suction, yielding an almost colorless filtrate. The

Cumulative efiect of the bisulfite addition product of 2- butyne-1,4-di0l on bright nickel plating Character of eleetrodeposit Electrolytic cell Open vessel Bisulfite Sulfa-oxygen compound Cone. Adduct (gm./1.) (mmoles/l Current density Appearance range of Appearance Leveling maximum (percent) brightness (a.s.f.)

Sodium napthalene-l,3,6-trisulfonate. 8. 0 0.0 Semi-bright, hazy 22. 5 4. 4 Bright 1. 5 4. 4 Sodium benzenesulfonate 16.0 0.0 Semi-bright, slight haze... 1. 5 4. 4 Bright 22. 5 4. 4 Brilliant. 54

EXAMPLE II An aqueous solution containing equivalent quantities of 4-methoxy-2-butyn-1-ol and potassium bisulfite was heated to reflux for several hours. After cooling, the solution was decolorized with activated carbon, filtered under suction, and methanol slowly added to the filtrate until no further precipitation occurred. The precipitate was filtered, dried in vacuo, and used in the plating bath without further purification.

A Watts nickel plating bath was prepared containing 300 grams per liter of nickel sulfate, grams per liter of nickel chloride, 41.25 grams per liter of boric acid, and 1.5 grams per liter of sodium naphthalene-1,3,6-trisulfonate. After adjusting the pH of the bath to 3.2 with sulfuric acid, an electrodeposit of nickel was formed on a steel panel in an open vessel, using a bath temperature of 60 (3., mild air agitation, and an average current density of 60 amperes per square foot. The electro deposit was only semi-bright and marred by hazy areas at the edges. Upon adding 8.8 millimoles per liter of the bisulfite addition product of equimolar quantities of 4- methoxy-Z-butyn-l-ol and potassium bisulfite (the preparation of which is described above) to this bath, a fully brilliant nickel electroplate free from clouds was formed over the entire surface of the panel. The difierence in roughness values ofthis electroplate and the unplated polished steel panel was 52 percent, indicating that the bipredominant product formed during the reaction was sodium 1,4-di-(B-hydroxyethoxy)-2-butene-2-sulfonate.

An electrodeposit of nickel was formed on a panel of polished steel in an open vessel, using a basic Watts bath having substantially the same composition (in nickel sulfate, nickel chloride, and boric acid) described previously. The deposite formed at a bath temperature of 60 C. and at a pH of 3.1 to 3.5 was matte. Upon adding 1.5 grams per liter of sodium naphthalene-1,3,6-trisulfonate and 4.4 millimoles per liter of the bisulfite adduct of l,4-di-(,B-hydroxyethoxy)-2-butyne to this bath, a bright to brilliant nickel electrodeposit was formed under the same plating conditions. Measurement of the roughness values (root mean square value in microinches) of both the unplated and brilliantly plated panel, using a Brush Surface Analyzer, showed that the roughness of the plated panel had decreased by over 70 percent from that of the unplated panel, indicating that the use of the bisulfite addition product in the bath is accompanied by leveling during the plating operation.

EXAMPLE V The bisulfite addition product of 1,4-di-(B-hydroxy- 'y-chloropropoxy)-2-butyne, which is the reaction product of 2-butyne-1,4-d'iol and epichlorohydrin, was prepared by adding an equimolar proportion of 1,4-di-(B-hydroxy- 7-ch1oropropoxy)-2-butyne to an aqueous solution of sodium bisulfite and refluxing the mixture for several hours. After cooling, the solution was diluted, decolorized with activated carbon, and filtered. Methanol was added to the filtrate, with vigorous stirring, to precipitate the bisulfite addition product. After filtration, the precipitate was dried in vacuo and used without further purification.

A very bright and ductile electrodeposit of nickel was formed on a polished steel panel in an open vessel using a plating bath and plating conditions similar to those described in Example IV with the sole exception that 2.2 millimoles per liter of the bisulfite addition product of 1,4-di-(fl-hydroxy-y-chloropropoxy)-2-butyne (the prepa ration of which is described immediately above) was used in the bath in place of the bisulfite adduct of 1,4-di-(fihydroxyethoxy) -2-butyne. The leveling etfect was 56 percent, indicating that the use of the bisulfite addition product in the bath is accompanied by leveling.

EXAMPLE VI Equimolar proportions of sodium bisulfite and 4-N,N- diethylamino-Z-but-yn-l-ol were dissolved in water and the mixture heated to reflux for about 4 hours. The mixture was diluted to approximately twice its volume with water, decolorized with activated carbon, filtered under suction, and the filtrate evaporated under vacuum, yielding a yellow powder which decolorizes on standing in air. The bisulfite adduct was recrystallized from water prior to use in a plating bath.

When nickel was electrodeposited in at Hull test cell at 50 C. to 60 C. from a high chloride nickel plating bath (pH=3.2 to 3.5) containing 150 grams per liter of" nickel sulfate, 248 grams per liter of nickel chloride, f

41.2 grams per liter of boric acid, and 7.5 grams per liter of sodium naphthalene-1,3,6-trisulfonate, the resultant electroplate was only semi-bright in the medium current density range of the test panel. Upon the addition of 4.4 millimoles per liter of the recrystallized bisulfite addition product described above to this bath, a very bright nickel deposit was formed over the current density range of from 1 to 80 amperes per square foot.

Using the same bath and identical plating conditions in an open vessel, except that 1 gram per liter of sodium 7 benzene-1,5-disulfonate was used in place of the sodium naphthalenea'l,3,6-trisulfonate and mild air agitation was provided, a nickel electrodeposit of 0.001 inch was formed on a roughened steel panel. ing operation, the surface roughness of the panel has been reduced by over 40 percent, demonstrating the leveling efiect exerted by the bisulfite adduct.

EXAMPLE VII Excellent results are also obtained when the. electroplate is formed from a plating bath containing the bisulfite addition product of an acetylenic compound containing one or more primary amino groups. To illustrate this principle, the bisulfite addition product of 1,4- diamino-Z-butyne was prepared in the standard manner by refluxing equivalent weights of 1,4-diamino-2-butyne and sodium bisulfite in an aqueous medium. The bisul: fite adduct was precipitated from the aqueous solution and dried in vacuo prior to use.

A semi-bright nickel deposit, marred by haziness, was formed on a polished brass panel in a Hull cell from a standard Watts sulfate-chloride-boric acid bath containing 3 grams per liter of sodium naphthalene-1,3,6-trisulfonate. The plating operation was conducted by a temperature of 50 C. and at a total current of two amperes. No agitation was provided. By adding only 4.4 millimoles per liter of the bisulfite addition product of equimolar quantities of 1,4-diamino-2-butyne and a bisulfite (as described above) to this bath, a very bright deposite free from haze was formed over the current density range of from 1 to 50 amperes per square foot. Increasing the concentration of the bisulfite adduct further increased the brightness of the electrodeposit.

Following the plat: H

EXAMPLE VIII Halogen-substituted acetylenic compounds also form bisulfite addition products which are exceptionally effective synergists when used in conjunction with a sulfooxygen brightening agent in nickel plating baths. In a Watts plating bath of the basic inorganic salt composition of Example II, containing 1.5 grams per liter of sodium naphthalene-l,3,6-trisulfonate, semi-bright deposits were obtained at current densities of from 20 to 40 amperes per square foot at a pH of 3.2 and a bath temperature of 55 to 60 C., with no agitation. However, when 4.4 millimoles per liter of the bisulfite addition product of equivalent weights of 1,4-dichloro-2-butyne and sodium bisulfite was added to this bath, the nickel deposit formed under these same conditions was exceptionally bright over the current density range from 10 to amperes per square foot.

EXAMPLE IX In each of the previous examples, the bisulfite addition product was prepared from an oz,ot'-dlSl.lbStltUtd acetylenic compound in which the same or different functional groups were present on carbon atoms adjacent to the acetylenic bond. The bisulfite addition products of tat-substituted acetylenic compounds, containing a single functional group on a carbon vicinal to the acetlyenic bond, have also proved exceptionally effective in nickel plating baths containing a sulfo-oxygen brightening agent.

7 Table V sets forth in detail the concentrations of the bisulfite addition product of a number of a-substituted acetylenic compounds (containing a single functional group) added to a standard Watts bath which also contained 4 grams per liter of sodium naphthalene-1,3,6- trisulfonate, and the character of the deposits produced from the bath. Each of the bisulfite adducts was prepared by refluxing equimolar quantities of the acetylenic compound and sodium bisulfite in aqueous medium for several hours, diluting the reaction mixture with water, decolorizing the mixture with activated carbon, filtering it under suction, and precipitating the bisulfite addition product from the filtrate by the addition of methanol. Plating operations were carried out in -a Hull test cell on polished brass cathodes for a period of 10 minutes using a bath temperature of '55" C., a pH of 3.2, and a total current of two amperes. No agitation was provided.

EXAMPLE X a,fl-Disubstituted acetylenic compounds containing the same or different functional groups on carbon atoms alpha and beta to the acetylenic bond, may also be used to prepare a bisulfite addition product for use in nickel plating baths in accordance with the invention. For example, the bisulfite addition product of 3-butyne-1,2- diol was prepared by refluxing the alkyndiol with an equimolar quantity of sodium bisulfite in an aqueous medium for 7 to 8 hours. After decolorizing the reaction mixture with activated carbon, it was filtered and the filtrate concentrated under vacuum until the bisulfite addition product began to crystallize. The concentrated filtrate was cooled in an ice chest, yielding a aooaoos powdery bisulfite addition product which could be used without further purification.

To a standard Watts sulfate-chloride-boric acid plating bath was added 4 grams per liter of sodium naphthalene 1,3,6-trisulfonate. A test panel which received a nickel electroplate firom this bath was semi-bright over a wide current density range, but exhibited slight haziness in the low and middle current density range. By adding 4.4 millimoles per liter of the bisulfite addition product of 3-butyne-l,2-diol to the electroplating solution, the

. nickel deposit became brilliant over the entire current density range of the panel. Increasing the concentration of the bisulfite addition product to 8 or 10 millimoles per liter did not increase the brightness nor extend the range further.

EXAMPLE XI Bisulfite addition products prepared from polyacetylenic compounds, in which the molecular structure contains two or more acetylenic bonds, have also proved exceptionally effective in nickel plating baths containing sulfo-oxygen brightening additives. Inpreparing these bisulfite addition products, the amount of bisulfite used may vary from an equimolar quantity (based on the molar proportion of polyacetylenic compound) to N times an equimolar quantity, where N is the number of acetylenic bonds per molecule of the polyacetylenic compound. Where only an equimolar quantity of bisulfite is reacted with the polyacetylenic compound, then the amount of unsaturation in the resultant adduct will be greater than when a stoichiometric quantity (N times an equimolar amount) of the bisulfite is employed. Both adducts may be used in nickel plating baths with equal facility.

Two diiferent bisulfite addition products were prepared from 2,4-hexadiyne-l,6-diol, using two equivalents of sodium bisulfite in the first case and an equimolar quantity in the second. The first bisulfite addition prodnot was prepared by dissolving in water one equivalent of 2,4-hexadiyne-1,6-diol for each two equivalents of sodium bisulfite and refluxing the mixture for about 6 hours. The solution was decolorized with activated carbon, filtered under suction, and the filtrate evaporated under vacuum, leaving the bisulfite addition product as a light tan powder. A similar procedure was used to prepare the second bisulfite addition product except that equimolar proportions of sodium bisulfite were employed in the reaction mixture. The work-up, however, was the same in both cases. To distinguish between the two adducts, the former (first) bisulfite addition product was designated as the bimolar adduct while the latter (second) was termed the equimolar bisulfite addition product.

Table VI sets forth the results observed when nickel was electrodeposited in a Hull cell on brass cathodes from a standard Watts plating bath containing varying concentrations of a representative sulfo-oxygen compound (sodium naphthalene-1,3,6-trisulfonate) together with one of the two bisulfite adducts.

In the foregoing examples of the invention, the bisulfite addition products of acetylenic compounds were used successfully in the standard Watts nickel electroplating bath, which is prepared by dissolving nickel sulfate, nickel chloride, and boric acid in water. Similar i i advantages are also attained when the bisulfite addition product is dissolved in other types of aqueous acidic nickel electroplating baths. For example, the bisulfite adducts are beneficial when used in straight nickel sulfate baths, in straight nickel chloride baths, and in various other nickel plating baths based on using nickel formate, nickel sulfamate, or nickel fluoborate as the nickel salt which is dissolved in the aqueous acidic solvent, and consequently the invention is applicable to electrodeposit-ion from any aqueous acidic solution of one or more nickel salts.

We claim:

1. The process for producing bright nickel deposits which comprises electrodepositing nickel from an aqueous acidic solution in which there is dissolved from about A to about grams per liter of a water-soluble sulfooxygen compound of the group consisting of unsaturated aliphatic sulfonic acids, mononuclear and binuclear aromatic sulfonic acids, heterocyclic sulfonic acids, mononuclear aromatic sulfinic acids, the alkali metal, ammonium, magnesium, and nickel salts of said acids, and mononuclear aromatic sulfonarnides and sulfonimides, and from about 1 to about 25 millimoles per liter of a water-soluble bisulfite addition product of an oz-Substituted acetylenic compound and N times an equivalent weight of a compound capable of forming a chain-carrying sulfite radical, where N is equal to the number of acetylenic bonds per molecule of the acetylenic compound, said u-substituted acetylenic compound containing the structural configuration CEC-( I]- B in which R is a substituent of the group consisting of hydroxy, alkoxy, formoxy, alkanoxy, halogen, polyoxy groups having the structure R0 O[CH;,CIEHO]DH in which R is a substituent of the group consisting of hydrogen, methyl, chloromethyl, hydroxymethyl, ethenyl, and glycidyl, and n is an integer from 1 to 20, and amino groups having the structure in which each of R and R" are substituents of the group consisting of hydrogen, alkyl, and hydroxyalkyl, said compound capable of forming a chain-carrying sulfite radical being selected from the group consisting of sulfurous acid, sulfur dioxide, and the alkali metal and metal bisulfites, sulfites, and metabisulfites, said bisulfite addition product containing the structural configuration CH=C- SIOSM in which M is a cation substituent selected from the group consisting of hydrogen, alkali metals, ammonium, magnesium, and nickel, and the olefinic carbon atom to which the $0 M radical is attached was originally one of the acetylenic carbon atoms.

2. The process for producing bright nickel deposits which comprises electrodepositiing nickel from an aqueous acidic solution of at least one nickel salt in which there is dissolved from about A to about 80 grams per liter of a water-soluble sulfo-oxygen compound of the group consisting of unsaturated aliphatic sulfonic acids, mono-nuclear and binuclear aromatic sulfonic acids, heterocyclic sulfonic acids, mononuclear aromatic sulfinic acids, the alkali metal, ammonium, magnesium, and nickel salts of said acids, and mononuclear aromatic sulfonamides and sulfonimides, and from about 1 to about 25 millimoles per liter of a water-soluble bisulfite addition product of an u,a'-disubstituted acetylenic compound and N times an equivalent weight of a compound capable of forming a chain-carrying sulfite radical, where N is equal to the number of acetylenic bonds per mole cule of the acetylenic compound, said OL,Ot'-dlSllbStltlltd acetylenic compound containing the structural configuration in which each of R and R are substituents of the group consisting of hydroxy, alkoxy, formoxy, alkanoxy, halogen, polyoxy groups having the structure 0[0H2( 3H-0]n ]1 in which R is a substituent of the group consisting of hydrogen, methyl, chloromethyl, hydroxymethyl, ethenyl, and glycidyl, and n is an integer froml to 20, and amino groups having the structure in which each of R and R" are substituents of the group consisting of hydrogen, alkyl, and hydroxyalkyl, said compound capable of forming a chain-carrying sulfite radical being selected from the group consisting of sulfurous acid, sulfur dioxide, and the alkali metal and metal bisulfites, sulfites, and metabisulfites, said bisulfite addition product containing the structural configuration in which M is a cation substituent selected from the group consisting of hydrogen, alkali metals, ammonium, magnesium, and nickel, and the olefinic carbon atom to which the $0 M radical is attached was originally one of the acetylenic carbon atoms.

3. The process for producing bright nickel deposits which comprises electrodepositing nickel from an aqueous acidic solution in which there is dissolved from about A to about 80 grams per liter of a water-soluble sulfooxygen compound of the group consisting of unsaturated aliphatic sulfonic acids, mononuclear and binuclear aromatic sulfonic acids, heterocyclic sulfonic acids, mononuclear aromatic sulfinic acids, the alkali metal, ammonium, magnesium, and nickel salts of said acids, and mononuclear aromatic sulfonamides and sulfonimides, and from about 1 to about 25 millimoles per liter of a water-soluble bisulfite addition product of an u-Sllbstituted acetylenic compound and N times an equivalent weight of a compound capable of forming a chain-carrying sulfite radical, where N is equal to the number of acetylenic bonds per molecule of the acetylenic compound, said u-substituted acetylenic compound having a structure represented by the formula R2 RzCECC IR1 in which each of R and R are substituents of the group consisting of hydrogen, alkyl, alkenyl, alkynyl, andhydroxy-substituted, alkoxy-substituted, and amino-substituted alkyl, alkenyl, and alkenyl groups, R is a substituent of the group consisting of hydrogen, halogen, alkyl, alkenyl, alkynyl, hydroxy-substituted, alkoXysubstituted, and amino-substituted alkenyl and alkynyl groups, and isubstituted-alkyl groups having thetstructural configuration R4 Rain 16 in which each of the R and R are substituents of the group consisting of hydrogen, alkyl, alkenyl, alkynyl, and hydroxy-substitut'ed, alkoXy-substituted, and amino-substituted alkyl, alkenyl, and alkynyl groups, and each of R and R are substituents of the group consisting of hydroxy, alkoxy, formoxy, alkanoxy, halogen, polyoxy groups having the structure in which R is a substituent of the group consisting of hydrogen, methyl, chloromethyl, hydroxymethyl, ethenyl, and glycidyl, and n is an integer from 1 to 20 and amino groups having the structure in which each of R and R" are substituents of the group consisting of hydrogen, alkyl, and hydroxyalkyl, said compound capable of forming a chain-carrying sulfite radical being selected from the group consisting of sulfurous acid, sulfur dioxide, and the alkali metal and metal bisulfites, sulfites, and metabisulfites, said bisulfite addition product containing the structural configuration EiO M in which M is a cation substituent selected from the group consisting of hydrogen, alkali metals, ammonium, magnesium, and nickel, and the olefinic carbon atom to which the $0 M radical is attached was originally one of the acetylenic carbon atoms.

4. The process for producing bright nickel deposits which comprises electrodepositing nickel from an aqueous acidic solution of at least one nickel salt in which there is dissolved from about A to about 80 grams per liter of a water-soluble sulfo-oxygen compound of the group consisting of unsaturated aliphatic sulfonic acids, mononuclear and binuclear aromatic sulfonic acids, heterocyclic s'ulfonic acids, mononuclear aromatic sulfonic acids, the alkali metals, ammonium, magnesium, and nickel salts of said acids, and mononuclear aromatic sulfonamides and sulfonimides, and from about 1 to about 25 millimoles per liter of a water-soluble bisulfite addition product of an oc,oc'-diSubStitl1ted acetylenic compound and N times an equivalent weight of a compound capable of forming a chain-carrying sulfite radical, where N is equal to the number of acetylenic bonds per molecule of the acetylenic compound, said a,a' -disubstituted acetylenic compound having a structure represented by the formula in which each of R R R and R are substituents'of the group consisting of hydrogen, alkyl, alkenyl, alkynyl, and hydroxy-substituted, alkoxy-substituted, and aminosubstituted alkyl, alkenyl, and alkynyl groups, and each of R and R are substituents of the group consisting of hydroxy, alkoxy, formoxy, alkanoxy, halogen, polyoxy groups having the structure. a

R0 -o-[cH2( H0],,H in which Ris a substituent of the group consisting of hydrogen, methyl, chloromethyl, hydroxymethyl, ethenyl,

and glycidyl, and n is an integer from 1 to 20, and amino groups having the structure RI! 7 V p in which each of R and R" are substituents of the group 17 consisting of hydrogen, alkyl, and hydroxyalkyl, said compound capable of forming a chain-carrying sulfite radical being selected from the group consisting of sulfurous acid, sulfur dioxide, and the alkali metal and metal bisulfites, sulfites, and metabisulfites, said bisulfite addition product containing the structural configuration in which M is a cation substituent selected from the group consisting of hydrogen, alkali metals, ammonium, magnesium, and nickel, and the olefinic carbon atom to which the 80 M radical is attached was originally one of the acetylenic carbon atoms.

5. The process for producing bright nickel deposits according to claim 3, wherein the bisulfite addition prodnot is formed from an u-hydroxy acetylenic compound having a structure represented by the formula $2 Ra-CEC-(E-Rr 6. The process for producing bright nickel deposits according to claim 3, wherein the bisulfite addition prodnet is formed from an a-haloacetylenic compound having a structure represented by the formula 7. The process for producing bright nickel deposits according to claim 3, wherein the bisulfite addition product is formed from an a-polyoxy acetylenic compound having a structure represented by the formula 8. The process for producing bright nickel deposits according to claim 3, wherein the bisulfite addition product is formed from an u-polyoxy acetylenic compound having a structure represented by the formula 18 9. The process for producing bright nickel deposits according to claim 4, wherein the bisulfite addition product is formed from an a,a-disubstituted acetylenic compound having a structure represented by the formula 10. The process for producing bright nickel deposits according to claim 4, wherein the bisulfite addition product is formed from an a,a'-disubstituted acetylenic compound having a structure represented by the formula 11. The process for producing bright nickel deposits according to claim 4, wherein the bisulfite addition product is formed from an u,oz'-diSLIbStitl1ted acetylenic compound having a structure represented by the formula 12. The process for producing bright nickel deposits according to claim 4, wherein the bisulfiate addition 634,394 Great Britain Mar. 22, 1950

Claims (1)

1. THE PROCESS FOR PRODUCING BRIGHT NICKEL DEPOSITS WHICH COMPRISES ELECTRODEPOSITING NICKEL FROM AN AQUEOUS ACIDIC SOLUTION IN WHICH THERE IS DISSOLVED FROM ABOUT 1/4 TO ABOUT 80 GRAMS PER LITER OF A WATER-SOLUBLE SULFOOXYGEN COMPOUND OF THE GROUP CONSISTING OF UNSATURATED ALIPHATIC SULFONIC ACIDS, MONNUCLEAR AND BINUCLEAR AROMATIC SULFONIC ACIDS, HETEROCYCLIC SULFONIC ACIDS, MONONUCLEAR AROMATIC SULFINIC ACIDS, THE ALKALI METAL, AMMONIUM, MAGNESIUM, AND NICKEL SALTS OF SAID ACIDS, AND MONONUCLEAR AROMATIC SULFONAMIDES AND SULFONIMIDES, AND FROM ABOUT 1 TO ABOUT 25 MILLIMOLES PER LITER OF A WATER-SOLUBLE NISULFITE ADDITON PRODUCT OF AN A-SUBSTITUTED ACETYLENIC COMPOUND AND N TIMES AN EQUIVALENT WEIGHT OF A COMPOUND CAPABLE OF FORMING A CHAIN-CARRYING SULFITE RADICAL, WHERE N IS EQUAL TO THE NUMBER OF ACETYLENIC BONDS PER MOLECULE OF THE ACETYLENIC COMPOUND, SAID A-SUBSTITUTED ACETYLENIC COMPOUND CONTAINING THE STRUCTURAL CONFIGURATION