US3655534A - Alkaline bright zinc electroplating - Google Patents

Abstract

Bright zinc is electrodeposited from alkaline zinc electrodepositing baths comprising an alkaline solution containing a source of zinc ions and an effective amount, as a brightening agent, of a bath-soluble reaction product obtained by the reaction of a nitrogen-containing heterocyclic compound with an acyclic amine having at least two functional groups separated by at least one different group, formaldehyde, and an epihalohydrin or a glycerol chlorohydrin.

Description

States Patent Kampe [151 3,655,534 [451 Apr. 11, 1972 [54] ALKALINE BRIGHT ZINC ELECTROPLATING [72] Inventor: Marcis M. Kampe, Cleveland Heights,

Ohio

Enthone, Incorporated, West Haven,

Conn.

[22] Filed: Feb. 24, 1970 [21] Appl.No.: 13,791

[73] Assignee:

[52] US. Cl. ..204/55, 204/DlG. 2 [51] Int. Cl. ..C23b 5/12, C23b 5/46 [58] Field of Search ..204/55 R, 55 Y, 43, 44, 114;

2,680,712 6/1954 Diggin et a1 ..204/55 Y 3,227,638 1/1966 Burnson et a1. ..204/55 Y X Primary Examiner-G. L. Kaplan Attorney-Elwood J. Schaffer and Roger J. Drew [5 7] ABSTRACT Bright zinc is electrodeposited from alkaline zinc electrodepositing baths comprising an alkaline solution containing a source of zinc ions and an effective amount, as a brightening agent, of a bath-soluble reaction product obtained by the reaction of a nitrogen-containing heterocyclic compound with an acyclic amine having at least two functional groups separated by at least one different group, formaldehyde, and an epihalohydrin or a glycerol chlorohydrin.

26 Claims, No Drawings BACKGROUND or THE INVENTION 1. Field of the Invention This invention relates to alkaline zinc electrodepositing and more particular to new alkaline bright zinc electrodepositing baths and to the electrodeposition of bright zinc therefrom. Additionally this invention isdirected to novel compositions and particularly compositions especially well suited .as' brightener additives for alkaline zinc electrodepositing baths.

'2. Description of the Prior Art Electrodeposition of zinc from alkaline cyanide zinc electroplatingbaths containing as a brightener additive a reaction product of hexamethylenetetramine with epichlorohydrin or alpha-chlorglycerol is disclosed in the prior art. Bright zinc has also been disclosedin the prior art as electrodeposited from cyanide zinc electroplating baths containing as brightener additive polyvinyl alcohol and a soluble reaction product of epichlorohydrin with ammonia or a primary amine.

The electrodeposition of bright zinc froma cyanide-free a1 kaline bath containing an alkanolamine, hexamethylenetetramine, or a mixture thereof is also known to the prior art.

SUMMARY OF THE INVENTION In accordance with the present invention, 1 have found that bright zinc can be electrodeposited from alkaline non-cyanide and cyanide zinc electrodepositing baths comprising an alkaline solution containing a source of zinc ions and an effective amount,'as a'brightening agent, of a bath-soluble'reaction product obtained by the reaction of a nitrogen-containing heterocyclic compound with an acyclic aliphatic primary amine containing two or more functional groups separated by one or more different groups or atoms, formaldehyde, and an epihalohydrin wherein the halogen atom is chloro or bromo or a glycerol chlorohydrin. The cyanide zinc electrodepositing bath can be a low cyanide content or a full or high cyanide content bath. The reaction product brighteners of this invention attained in the zinc electrodeposits a considerably or a quinoline, wherein R is hydrogemmethyl, chloro, bromo, amino, cyano, vinyl, propanol or COOM wherein M is hydrogen or a hydrophilic cation, for example an alkali metal, e.g. Na or K", cation, R, is hydrogen 'or amino with the proviso that when R is amino R is methyl, and R is hydrogen, methyl or -COOM wherein M is hydrogen or a hydrophilic cation, for example an'alkali metal, e.g. Na or K, cation.

The acyclic amine'reactant for forming the soluble reaction product brightener can be any acyclic aliphatic amine having two or more functional groups. Thus primary, secondary and tertiary amines are utilizable as the amine reactant so long as the amine has two or more functional groups. The two or more functional groups, for example ---OH and -Nl-l, groups, are separated by one or more different groups or atoms in the amine molecule. Exemplary ,of the amine reactant are monoethanolamine, diethanolamine, triethylenetriamine,

.tetraethylenepentamine, triethanolamine, ethylenediamine and diethylenetriamine. The functional groups in theamines enumerated immediately supra include the -NH OH, and NH groups. By functional group as used herein in referring to the amine reactant having at least two functional under the reaction conditions of the invention. It is essential groups is meant a group or radical capable of reacting with another reactant, group or radical in the reaction mixture, such as by an addition reaction'or a condensation reaction,

7 product brightener herein will usually be of the formula and the epihalohydrin or glycerol chlorohydrin, and a liquid diluent therefor. Usually the brightener additive of this invention comprises a solution of such reaction product in a liquid aqueous solvent. I

- It is unnecessary to recover the reaction product of this invention from the aqueous reaction product mixture, and the reaction product of this invention is utilizable as or in the brightener additive composition of this invention when in solution in the liquid diluent or solvent of the reaction mixture or mass. Other constituents can be added to the brightener additive composition, if desired, such as the brighteners and other additives of the prior art hereinafter disclosed.

The reaction product brighter herein is added to the alkaline cyanide or.non-cyanide zinc electrodepositing baths herein in a minor amount, sufficient to impart brightness to the electrodeposited zinc. Thereaction product brightener is I cyclic or bicyclic heterocyclic compound and is usually of the 75 formulae Cr CHCH2X wherein X is chloro M15656. Such compounds include epichlorohydrin and epibromohydrin.

The glycerol chlorohydrin reactant will usually be of the formula:

I wherein at least one but not mTiETlTEn two Xs are hydroxy over wide limits. With lesser concentrations of the reaction product in the solutions, more of the solution can be added to the zinc electrodepositing bath if required than when greater concentrations of the reaction product. As previously disclosed herein, such brightener additive composition is ordinarily the reaction product mixture or mass taken as such from the reactor, and without recovery of the reaction product from the mixture.

Brighteners and other additive agents well known in the prior art for cyanide zinc electroplating baths are utilizable in the non-cyanide and cyanide alkaline zinc electrodepositing baths herein together with the reaction product brightener of this invention. These prior art brighteners and addition agents including agents for inhibiting void formation and surface active agents can be added separately to the zinc eleetrodepositing bath or may be added as a constituent of the compositions of the present invention. When present in such additive compositions of this invention, the prior art brightener or additive can be present therein in any suitable amount. Such prior art brightencrs and addition agents include, for example, armatic aldehydcs, e.g. piperonal, anisic aldehyde, vanillin, salicylaldehydc, polyvinyl alcohol, modified polyvinyl alcohol, e.g. oxidized polyvinyl alcohol, gelatin, polyether alcohols, polyesters, glue and peptone.

The reaction temperature for forming the soluble reaction product brightener herein can be room temperature. Broadly the reaction temperature can be from room temperature to reflux temperature of the reaction mixture inclusive. Higher temperature up to and including reflux temperature speed up the reaction whereas lower temperatures and room temperature require longer reaction times for formation of the reaction product.

The proportions of the reactants are not especially critical and can be varied over broad ranges.

The reaction time to yield the soluble reaction product brightener is, as is hereinbefore disclosed, dependent on the particular reaction temperature employed with room temperature reacting requiring considerably longer times, as long as 12 hours, then elevated temperatures of 60 C. and up to reflux temperature which require typically about 1-2 hours to yield the reaction product brightener.

The reaction product brightener herein is light brown to dark brown in color, and soluble in water and in the alkaline zinc electroplating baths herein. Under certain conditions, the reaction product herein may have a reddish coloration or tint in its brown color. When the reaction product is concentrated by expelling the water from the reaction product mass or mixture, the reaction product herein is a viscous semi-solid or solid.

That the reactants have reacted to form the reaction product brightener of this invention is evidenced by the evolution of heat by the exothermic reactions, a color change in the reaction mixture with the color thereof changing from a water white to a light brown to dark brown color, and the fact the the epichlorohydrin, which is initially insoluble in and suspended in the aqueous diluent, passes into solution in the aqueous diluent after reacting.

The reactants can all be mixed together and reacted together in the mixture, or they can be reacted together following a preferred sequence of adding reactants to the reactor as is hereinafter disclosed.

The reactants herein are reacted together to form the reaction product brightener in the presence of an aqueous liquid diluent, for example water, an aqueous solution of a l-3 C alkanol, e.g. methanol, ethanol or propanol. When water is the diluent, which is usually the case, the water includes that contributed by theformalin as well as that contributed by any aqueous solution of another reactant or reactants, for instance an aqueous solution of the primary amine, and also the water formed by condensation reactions occurring. The amount of aqueous diluent can be varied over a wide range and the amount of water in or as the diluent is not especially critical except that when epichlorohydrin and monoethanolamine are reactants, an amount of water is utilized which is sufficient to prevent the explosive reaction of the epichlorohydrin in the presence of the monoethanolamine. The water does not appear to be an inert diluent when an epihalohydrin, for instance epichlorohydrin is a reactant, inasmuch as it is believed that the water reacts with the epichlorohydrin to open up the epoxy ring to result in two hydroxyl groups in addition to the chlorine atom.

The source of zinc ions in the aqueous alkaline electrodepositing baths herein can be zinc cyanide, Zn(CN) and/or an alkali metal zincate such as sodium zincate, Na in0 or potassium zincate, K Zn O in the cyanide baths, and

an alkali metal zincate such as sodium zincate or potassium zincate in the non-cyanide baths herein. The cyanide and noncyanide alkaline baths also contain an alkaline material, usually an alkali metal hydroxide, eg sodium or potassium hydroxide, with the zinc-containing compound dissolved in the aqueous alkaline solution. An alkali metal carbonate, e.g. sodium or potassium carbonate may also be a constituent of the cyanide and non-cyanide alkaline baths herein.

The electrodepositing of the bright or semi-bright zinc in accordance with the invention is carried out by passing a DC electrical current, from an'anode or anodes through the alkaline non-cyanide or cyanide zinc electroplating bath solution containing the reaction product brightener of this invention to a cathode or cathodes which is the article or articles or objects on which the zinc is to be electrodeposited. The electrodepositing can be carried out at room temperature and at temperatures above room temperature up to about 50 C. Current densities of l-200 amps/sq. ft. are typically utilized. The anode or anodes may be conventional anodes well known in the art.

An aromatic amine of the formula IIIH:

wherein R is H, --NI-l or OH can also be a reactant herein for forming the reaction product brightener when added together with gamma picoline as the nitrogen-containing heterocyclie compound reactant. Such aromatic amine of the formula immediately supra includes aniline and p-phenylenediamine. The other reactants, viz. the acyclic amine having at least two functional groups, formaldehyde, and the 'epihalohydrin or glycerol halohydrin, are also reactants when such aromatic amine is utilized as a reactant together with the gamma picoline as reactant. The ratio of the aromatic amine of the formula supra to the gamma picoline as reactants is not especially critical and can be varied over a broad range.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The preferred amine having two or more functional groups as reactant herein is monoethanolamine.

When an epihalohydrin, for instance epichlorohydrin is a reactant, the amount of water utilized in or as the aqueous diluent is preferably at least equimolar with the epichlorohydrin, more preferably a moderate or large excess of water over such equimolar amount, for instance about 600 percent excess of water over such equimolar amount.

Preferably the bath-soluble reaction product brightener herein is obtained or prepared by slowly adding an aqueous formaldehyde solution of 37 percent formaldehyde concentration known as formalin to a mixture of the amine having two or more functional groups, preferably monoethanolamine, the nitrogen-containing heterocyclic compound, and the aqueous diluent while agitating the liquid mixture. Such slow or gradual addition of the aqueous formaldehyde solution is usually over a period of about 15 to about 30 minutes. Exothennic heat is liberated during the formaldehyde addition and it may or may not be necessary to cool the reaction mixture to about room temperature or slightly above room temperature prior to the addition of the epihalohydrin. If cooling is required prior to the epihalohydrin addition, the cooling may be effected by indirect heat exchange of the reaction mixture with a fluid coolant, for instance by cooling water circulating through the jacket of a jacketted reactor, or, if desired, the cooling can be effected by simply allowing the reaction mixture to cool to about room temperature or slightly thereabove. The epihalohydrin, preferably epichlorohydrin is slowly added to the resulting liquid mixture, usually over a The reactants are preferably reacted to form the reaction product brightener in proportions within the molar ranges of about 0.5 1.5 mole of the amine having two of more functional groups, about 0.1 0.3 mole nitrogen-containing heterocyclic compound, about 1.0 3.0 moles formaldehyde, and about 0.5 1.5 mole epihalohydrin or glycerol chlorohydrin.

The reaction product. brightener of this invention is preferably added to the alkaline cyanide or non-cyanide zinc electrodepositing baths herein in amount within the range of Zinc plating tests were separately carried out in alkaline non-cyanide, low cyanide and full or high cyanide content zinc electroplating baths to zinc-plate Hull test panels. The plating was carried out in the Hull cell with the Hull cell panel in each test run connected as cathode in the bath. The operating conditions for the Hull cell were an operating current of 1-5 amps, usually 2 amps, room temperatureof the bath, and a plating time of 5 minutes. A reaction product brightener of this invention prepared as hereafter disclosed and utilizing as the nitrogen-containing heterocyclic compound reactant for each test run that nitrogen-containing heterocyclic compound specified in the Table l hereinafter set forth was added in amount of about 1 c.c. to an alkaline zinc'electroplating bath of one of the following compositions:

Non- Low High Cyanide Cyanide Cyanide Bath Bath Bath Zinc(oz./gal.) 0.98 4.7

Sodium hydroxide (oz./gal.) Water As indicated, certain of the baths were non-cyanide, i.e. were free of cyanide; certain of the baths were low cyanide baths containing 1 oz/gal. of sodium cyanide; and certain of the baths were full cyanide baths, i.e. high cyanide content baths, containing 12.7 oz/gal. of sodium cyanide.

The reaction product brightener was prepared by the following procedure:

Fifty (50) ml. water was added to a reaction vessel equipped with a reflux condenser. 31.5 g. (approximately 0.5 mole) monoethanolarnine, and 6.0 g. (0.1 mole) isopropanol were added to the water in the reaction vessel. The mixture was stirred'and the particular nitrogen-containing heterocyclic compound in the amount specified in Table l hereinafter was added thereto. Sixty (60.0) .g. (approximately 0.75 mole) aqueous 37 percent formaldehyde was then added to the mixture in the reaction vessel while stirring the mixture, and the reaction mixture cooled to near room temperature. Forty-six (46.0.) g. (0.5 mole) epichlorohydrin was then slowly added to the mixture in the reaction vessel with stirring of the mixture ,during such addition. The epichlorohydrin was added to-the mixture over an approximately 60 minute period. The resulting reaction mixture was then refluxed for k hour, cooled and stored in a container.

In the Table l of test results which follows, H cd" means a high current density of 40-100 amplft M ed" means a middle current density of 20 amp/ft up to amp/ft; and L ed" means a low current density of slightly above 0 and up to 20 1 amp/ft? Also in the following Table l, L-l-l cd means in the low, middle and high current density ranges as set forth immediately above, H-M ed means in the high and middle c ur TAB LE I Amount of nitrogen containing heterocyclic compound Test Run Particular nitrogen containing hetcrocyreactant utilized, mole/0.5 Non-cyanide zinc Low-cyanide zinc High cyanide zinc Number clic compound reactant ml. of epichlorohydrin plating bath plating bath plating bath 1 Alpha-plcoline 0.1 mole Br, H cd F, Br, L-H cd F, Br, 1,11 ed.

. F, Br, H-M ed F; Br, L-H ed F, Br, L-H ed. Br, H-M cd Br, M cd F, Br, M-L ed. Br, H-M cd 13, Br, L-H cd F, (1131, L and H 5 Beta-picoline 0.1 mole F, Br, L ed F, Br, H-L ed F, Br, M-L cd I CH;

6 Gamma-picollne 0.1 mole V, Br, H-M cd Br, H-M cd Br, M ed \NJ ,7 v

7 Gamma-picolino and aniline. 0.1 mole and 0.1 mole F, Br, M-L ed F, Br, L-H cd F, Br, M ed.

Table 1 Cominued Amount of nitrogen containing heterocyclic compound Test Run Particular nitrogen containing heterocyreactant utilized, mole/0.6 Non-cyanlde zinc Low-cyanide zinc High cyanide zinc Numbor clic compound reactant m1. of eplchlorohydnn plating bath plating bath plutlngbnth 8 lsoqu o ne ole V, Br, M ed Br, 11-1, cd Br, n.

Same as above -05 mole Br, H-L ed Br, H-L ed F, Br, M-L cd.

Plcolinlc acid -1 mole Dull, H-L ed F, Br, H-L cd F, Br, M-L cd.

C 0 O H J* 11 Isonicotlnlc acid -1 mole Dull, H-L cd F, Br, H-L cd F, Br, H-L ed C 0 O H Q 12 Nlcotinic acli 0.1 mole Br, H-L ed Br, H-L cd V, Br, H-L cd (To 0 OH N r V .V

13 Condensation reaction product of mono- Does not apply F, Br, L ed Dull, 3. ed n, ed

ethanol-amino, Iormaldchydo and cplchlorohydrin.

14 Pyridine 111016 Dull, H-L cd F, Br, HL cd F, Br, H-L ed 15 py d e v, Br, H-M cd Br, M-L cd Br, M-L ed HC=CII2 16 4-cyanopyridine -1 mole Dull, H-L cd F, Br, H-L cd F, Br, H-L cd CN J 17 Hhloropyridlne -1 mole F, Br, M-L cd F, Br, H-L ed F, Br, M-L cd 18 4-propanolpyridinc -1 mole Br, H-L cd Br, H-L ed Br, H-L cd CH2-CH2-CII2-CH N 7 7M, 7 r W W V V n ,r

19 Ggrlnmii-picoline and para-phenylene- 0.1 mole and 0.05 mole V, Br, M ed V, Br, H-M cd Br, M ed am no CH3 and N H2 Table l Continued Amount of nitrogen containing heterocyclic compound Test Run Partlcular mtrogen containing heterocyreactant utilized, mole/0.5 Non-cyanide zinc Low-cyanide zinc High cyanide zinc Number clio compound reactant ml. of epichlorohydrin plating bath plating bath plating bath 2o -L- Same above 0.08 mole and 0.0255016 v, Br, M ed Br, H-L cd Br, M-L ed 21 Ganma-picoline and Z-methylpyraz- 0.08 mole and 0.07 mole V, Br, M ed F, Br, H cd I Br, H-M ed (His and N l N CH: N

22 4-plcolylamina 0.1 mole Br, M ed Br, M-L cd Br, H-M cd 7 NH: @CHa N 23 2,4,6collidino 0.1 mole Dull; H-L cd Dull, H-L ed Dull, H-L ed CH3 I HaC J-OH: N

24 2-methylpy'razine 0.1 mole 5. Br, 11-1. cd Br, H-L ed F, Br, H-L ed N k CH3 25 2-pyrazinecarboxylic acid 0.1 mole Dull, H-L ed F, Br, H-L cd F, Br, H-L cd N C O O H The good results in brightness of the electrodeposited zinc obtained utilizing thereactionproductbrighteners of this invention in the zinc electrodepositingbaths is-shown by the. test results of Table l. I

' Additional zinc platingtests were carried. out'to evaluatevarious reaction products asxbrightener additivesto non-cya-. nide, low cyanide, and, full or high cyanide zinc electroplating baths. Test Runs No.-s 26-38 whichfollow are concerned with electroplating of zinc from non-cyanide, i.e. cyanide-free, alkaline zinc electrodepositing baths, Test Runs No.s 39-55 which follow relate to electroplating of zinc from low cyanide content alkaline zinc electrodepositing baths, and Test Runs No.s 56-67 also which follow are concerned with electroplating of zinc from .full. cyanide, i.e. high cyanidecontenu'alkaline zinc electrodepositing baths.

The reactionproduct brightener for thezinc electrodepositing baths of Test Runs No.s 26-67 hereafter set forth was prepared by combining withwater 0.5 mole of the particular amine having two or more functional groups and .0.1 mole isopropanol. When a nitrogen-containing heterocyclic compound was a reactant, 0.1 mole of nicotinic acid or 0. 1 mole of gamma picoline was mixed together with the aqueous mixture 5 of the amine and isopropariol. 0.75 mole formaldehyde in aqueous solution of 37 percent. formaldehyde concentration was then stirred into the thus-obtained-mixture, and the resulting mixture allowed to cool to room temperature.

Epichlorohydrin in the amount of 0.5 mole, or-0.5 mole of Reaction product of die'thanolamine; formal- Esters?9 eia i ygbey t ebeat829%.

TEST RUN NO. 27

Reaction product of diethanolamine, aqueous forrnaldehyde of 37 percent formaldehyde concentration, epichlorohydrin andnicotinic acid, in amount of l V: ml., was addedto an alkaline non-cyanide zinc electroplating bath of the same composition as in Test Run No. 26 in a 267 ml. Hull test cell.

The zinc electrodeposit on the Hull test panel was semibright in the range of about 4-37 amps/ft and bright in the range of slightly above 0 up to about 4 amps/ft? TEST RUN NO. 28

Reaction product of diethanolamine, aqueous formaldehyde of 37 percent formaldehyde concentration, epichlorohydrin and 'y-picoline, in amount of 1 ml., was added to an alkaline non-cyanide zinc electroplating bath of the same composition as in Test Run No. 26 in a 267 ml. Hull test cell.

The zinc electrodeposit on the Hull test panel .was semibright in the range of about 55-85 amps/ft.

11 TEST RUN NO. 29

Reaction product of triethanolamine, aqueous formaldehyde of 37 percent formaldehyde concentration and epichlorohydrin, in amount of l /2 ml., was added to an alkaline non-cyanide zinc electroplating bath of the same composition as in Test Run No. 26 in a 267 ml. Hull test cell.

The zinc electrodeposit on the Hull test panel was semibright in the range of slightly above up to about 4 amps/ft? TEST RUN NO. 30

Reaction product of triethanolamine, aqueous formaldehyde of 37 percent formaldehyde concentration, epichlorohydrin and y-picoline, in amount of 1 A ml., was added to an alkaline non-cyanide zinc electroplating bath of the same composition as in Test Run No. 26 in a 267 ml. Hull test cell.

The zinc electrodeposit on the Hull test panel was bright in the range of about 14l00 amps/ft? TEST RUN NO. 31

Reaction product of hexamethylenetetramine, aqueous formaldehyde of 37 percent formaldehyde concentration, epichlorohydrin and nicotinic acid, in amount of 1 V. ml., was added to an alkaline, aqueous non-cyanide zinc electroplating bath containing 0.99 oz./gal. Zn and 9.4 oz./gal. NaOH in a 267 ml. Hull test cell.

The zinc electrodeposit on the Hull test panel was bright in the range of slightly above 0 to 100 amps/ft.

TEST RUN NO. 32

Reaction product of hexamethylenetetramine, aqueous formaldehyde of 37 percent formaldehyde concentration, epichlorohydrin and 'y-picoline, in amount of 1 /2 ml., was added to an alkaline, aqueous non-cyanide zinc electroplating bath containing 0.99 oz./gal. Zn and 9.4 oz./gal. NaOH in a 267 ml. Hull test cell.

The zinc electrodeposit on the Hull test panel was bright in the range of slightly above 0 to 98 amps/ft? TEST RUN NO. 33

Reaction product of ethylenediamine, aqueous formaldehyde of 37 percent formaldehyde concentration, epichlorohydrin and nicotinic acid, in amount of 541 ml., was added to an alkaline, aqueous non-cyanide zinc electroplating bath containing 0.99 oz./gal. Zn and 9.4 oz./gal. NaOH in a 267 ml. Hull test cell. 7

The zinc electrodeposit on the Hull test panel was semibright in the range of slightly above 0 to about 62 amps/ft? TEST RUN NO. 34

Reaction product of ethylenediamine, aqueous formaldehyde of 37 percent formaldehyde concentration, epichlorohydrin and y-picoline, in amount of V1 ml., was added to an alkaline, aqueous non-cyanide zinc electroplating bath containing 0.99 oz./gal. Zn and 9.4 oz./gal. NaOH in a 267 ml. Hull test cell.

The zinc electrodeposit on the Hull test panel was bright in the range of slightly above 0 to about 60 amps/ft.

TEST RUN NO. 35

Reaction product of monoethanolamine, aqueous formaldehyde of 37 percent formaldehyde concentration, and glycerol dichlorohydrin, in amount of 1% ml., was added to an alkaline, aqueous non-cyanide zinc electroplating bath containing 0.99 oz./gal. Zn and 9.4 oz./gal. NaOH in a 267 ml. Hull test cell.

The zinc electrodeposit on the Hull test panel was dull in the range of from 0 to about ampslft and was a burnt, dark deposit in the range of about 20 to 100 amps/ft.

1 TEST RUN NO. 36

Reaction product of monoethanolamine, aqueous formaldehyde of 37 percent formaldehyde concentration, glycerol dichlorohydrin and 'y-picoline, in amount of 1% ml., was added to an alkaline, aqueous non-cyanide zinc electroplating bath containing 0.99 oz./gal. Zn and 9.4 oz./gal. NaOH in a 267 ml. Hull test cell. i

The zinc electrodeposit on the Hull test panel was semibright in the range of about 12 to about 40 amps/ft? TEST RUN NO. 37

Reaction product of ethylenediamine, aqueous formaldehyde of 37 percent formaldehyde concentration, and glycerol monochlorohydrin, in amount of 1 /2 ml., was added to an alkaline, aqueous non-cyanide zinc electroplating bath containing 0.99 oz./gal. Zn and 9.4 oz./gal. NaOH in a 267 ml. Hull test cell.

The zinc electrodeposit on the Hull test panel was dull in the range of 0 to about 35 ampslft and a burnt, dark deposit in the range of about 35 to amps/ft TEST RUN NO. 38

Reaction product of ethylenediamine, aqueous formaldehyde of 37 percent formaldehyde concentration, glycerol monochlorohydrin, and nicotinic acid in amount of 1% ml., was added to an alkaline, aqueous non-cyanide zinc electroplating bath containing 0.99 oz./gal. Zn and 9.4 oz./gal. NaOH in a 267 ml. Hull test cell.

The zinc electrodeposit on the Hull test panel was bright in the range of about 10 to about 48 amps/ft That the reaction product brightener of the present invention considerably enhanced the brightening effect, the range of brightness, or both of the zinc electrodeposited from the cyanide-free zinc plating bath is shown by Test Runs N0. 27, 28, 3034, 36 and 38 wherein the plating baths contained the reaction product brightener of the invention as compared with Test Runs 26, 29, 35 and 37 wherein the baths contained as additive a reaction product not of the present invention.

TEST RUN NO. 39

TEST RUN NO. 40 7 Reaction product of diethanolamine, aqueous formaldehyde of 37 percent formaldehyde concentration, epichlorohydrin and nicotinic acid, in amount of 1 A2 ml., was added to the alkaline low cyanide zinc electroplating bath of the same composition as in Test Run No. 39 in a 267 ml. Hull test cell.

The zinc electrodeposit on the Hull test panel was bright over the entire range of slightly above 0 to 100 amps/ft? TEST RUN NO. 41

Reaction product of diethanolamine, aqueous formaldehyde of 37 percent formaldehyde concentration,

epichlorohydrin and 'y-picoline, in amount of V4 ml., was added to an alkaline, low cyanide zinc electroplating bath of the same composition as in Test Run No. 39 in a 267 ml. l-lull test cell.

The zinc electrodeposit on the Hull test panel was bright over the entire range of slightly above 0 to 100 amps/ft? TEST RUN NO. 43

Reaction product of triethanolamine, aqueous formaldehyde of 37 percent formaldehyde concentration, epichlorohydrin and nicotinic acid, in amount of l 7% ml., was added to an alkaline, aqueous non-cyanide zinc electroplating bath of the same composition as in Test Run No. 39 in a 267 ml. l-lull test cell.

The zinc electrodeposit on the Hull test panel was bright in the range of about 10-90 amps/ft? TEST RUN NO. 44

Reaction product of hexamethylenetetramine, aqueous formaldehyde of 37 percent formaldehyde concentration, epichlorohydrin and nicotinic acid, in amount of A ml., was added to the alkaline low cyanide zinc electroplating bath of the same composition as in Test Run No. 39 in a 267 ml. l-lull Test cell.

The zinc electrodeposit on the Hull test panel'was bright over the range of slightly above 0 to 100 ampslft TEST RUN NO. 45

Reaction product of hexamethylenetetramine, aqueous formaldehyde of 37 percent formaldehyde concentration,

epichlorohydrin and 'y-picoline, in amount of A ml., was

added to the alkaline low cyanide zinc electroplating bath of the same composition as in Test Run No. 39 in a 267 ml. Hull Test cell. i

The zinc electrodeposit on the Hull test panel was bright over the entire range of slightly above 0 to .100 amps/ft.

TEST RUN NO. 46

Reaction product of ethylenediamine, aqueous formaldehyde of 37 percent formaldehyde concentration and epichlorohydrin, in amount of ml., was added to the alkaline low cyanide zinc electroplating bath of the same composition as in Test Run No. 39 in a 267 ml. Hull Test cell.

The zinc electrodeposit on the Hull test panel was semibright over the range of slightly above 0 to 100 amps/ft TEST RUN NO. 47

Reaction product of ethylenediamine, aqueous formaldehyde of 37 percent formaldehyde concentration, epichlorohydrin and nicotinic acid, in amount of A ml., was added to the alkaline low cyanide zinc electroplating bath of the same composition asin Test Run No. 39 in a 267 ml. Hull Test cell.

The zinc electrodeposit on the Hull test panel was bright in the range of about 20-100 amps/ft? TEST RUN NO. 48

Reaction product of triallylamine, aqueous formaldehyde of 37 percent formaldehyde concentration and epichlorohydrin, in amount of A ml., was added to the alkaline low cyanide zinc electroplating bath ofthe same composition as in Test Run No. 39in a 267 ml. Hull Test cell.

The zinc electrodeposit on the Hull test panel was cloudy over the entire range of slightly above 0 to 100 amps/ft? TEST RUN NO. 49

Reaction product of triallylamine, aqueous formaldehyde of 37 percent formaldehyde concentration, epichlorohydrin and 'y-picoline, in amount of a added 'm' the alkaline low cyanide zinc electroplating bath of the same composition as in Test Run No. 39 in a 267 ml. Hull Test cell.

r The zinc electrodeposit on the Hull test panel was bright in the range of about 2-40 amps/ft.

TEST RUN NO. 50

Reaction product of diethylenetriamine, aqueous femaldehyde of 37 percent formaldehyde concentration and epichlorohydrin, in amount of 14 ml., was added to'the alkaline low cyanide zinc electroplating bath of the same composition as in Test Run No. 39 in a 267 ml. Hull Test cell.

The zinc electrodeposit on the Hull test panel was dull in the range of about 5-94 amps/ft, and semi-bright in the range of about 94-100 amps/ft".

TEST RUN NO. 51

Reaction product of diethylenetriamine, aqueous forrnaldehyde of 37 percent formaldehyde concentration, epichlorohydrin and nicotinic acid, in amount of A ml., was added to the alkaline low cyanide zinc electroplating bath of the same composition as in Test Run 39 in a 267 ml. Hull Test cell.

The zinc electrodeposit on the Hull test panel was semibright in the range of about 36-87 amps/ft, and bright in the range of about 87-100 amps/ft? TEST RUN NO. 52

Reaction product of monoethanolamine, aqueous formaldehyde of 37 percent formaldehyde concentration, glycerol dichlorohydrin and nicotinic acid, in amount of 1 V2 ml., was added to the alkaline low cyanide zinc electroplating bath of the same composition as in Test Run No. 39 in a 267 ml. l-lull Test cell.

The zinc electrodeposit on the Hull test panel was bright over the entire range of slightly above 0 to amps/ftf".

TEST RUN NO. 53

TEST RUN NO. 54

Reaction product of monoethanolamine, aqueous formaldehyde of 37 percent formaldehyde concentration, glycerol monochlorohydrin, and 'y-picoline, in amount of 1 ml., was added to the alkaline low cyanide zinc electroplating bath of the same composition as in Test Run No. 39 in a 267 ml. Hull test cell.

The zinc electrodeposit on the Hull test panel was bright in the range of about 8 to 100 amps/ft TEST RUN NO. 55

Reaction product of ethylene diamine, aqueous formaldehyde of 37 percent formaldehyde concentration, glycerol monochlorohydrin, and nicotinic acid, in amount of l 9% ml., was added to the alkaline low cyanide zinc electroplating bath of the same composition as in Test Run No. 39 in a 267 ml. Hull test cell.

The zinc electrodeposit on the Hull test panel was bright in the range of about 6 to about 93 amps/ft A comparison of the zinc deposits from the low cyanide plating baths of Test Run No.s 40, 41, 43-45, 47, 49 and 51-55 containing a reaction product brightener of the invention with the zinc deposits from the low cyanide baths of Test Run No.s 39, 42, 46, 48 and 50 containing asadditive a reaction product not of the present invention, evidences the considerable increase in brightening effect, range of brightness, or both provided by the reaction product brighteners of the present invention.

TEST RUN NO. 56

Reaction product of diethanolamine, aqueous formaldehyde of 37 percent formaldehyde concentration, epichlorohydrin and nicotinic acid, in amount of /2 ml., was added to an alkaline aqueous full or high cyanide zinc electroplating bath containing 4.5 oz./gal. Zn, 10.3 oz./gal. NaOH and 13.4 oz./gal. NaCN in a 267 ml. Hull test cell.

The zinc electrodeposit on the Hull test panel was bright over the entire range of slightly above 0 to 100 amps/ft? TEST RUN NO. 57

TEST RUN NO. 58

Reaction product of triethanolamine, aqueous formaldehyde of 37 percent formaldehyde concentration, and

epichlorohydrin, in amount of 1 ml., was added to an alkaline aqueous full or high cyanide zinc electroplating bath containing 4.5 oz./gal. Zn, 10.3 oz./gal. NaOH and 13.4 oz./gal. NaOH and 13.4 oz./gal. NaCN in a 267 ml. Hull test cell.

The zinc electrodeposit on the Hull test panel was cloudy in the range of slightly above 0 to about 7 amps/ft and bright in the range of about 7-100 amps/ft.

TEST RUN NO. 59

Reaction product of hexamethylenetetramine, aqueous formaldehyde of 37 percent formaldehyde concentration, epichlorohydrin and nicotinic acid, in amount of /2 ml., was added to an alkaline aqueous full or high cyanide zinc electroplating bath containing 4.5 oz./gal. Zn, 10.3 o2./gal. NaOH and 13.4 oz./gal. NaCN in a 267 ml. Hull test cell.

The zinc electrodeposit on the Hull test panel was bright over the entire range of slightly above 0 to 100 amps/ft TEST RUN NO. 60

Reaction product of hexamethylenetetramine, aqueous formaldehyde of 37 percent formaldehyde concentration, epichlorohydrin and y-picoline, in amount of 5 4 ml., was added to an alkaline aqueous full or high cyanide zinc electroplating bath containing 4.5 oz./gal. Zn, 10.3 oz./gal. NaOH and 13.4 oz./gal. NaCN in a 267 ml. Hull test cell.

The zinc electrodeposit on the Hull test panel was bright over the entire range of slightly above 0 to 100 amps. ft although a cloud was present in the deposit.

TEST RUN NO. 61

Reaction product of ethylene diamine, aqueous formaldehyde of 37 percent formaldehyde concentration, epichlorohydrin and nicotinic acid, in amount of V1 ml., was added to an alkaline aqueous full or high cyanide zinc electroplating bath containing 4.5 oz./gal Zn, 10.3 oZ./gal. NaOH and 13.4 oz./gal. NaCN in a 267 ml. Hull test cell.

The zinc electrodeposit on the Hull test panel was bright over the entire range from slightly above 0 to 100 amps/ft".

TEST RUN NO. 62

Reaction product of ethylenediamine, aqueous formaldehyde of 37 percent formaldehyde concentration, epichlorohydrin and 'y-picoline, in amount of A ml., was added to an alkaline aqueous full or high cyanide zinc electroplating bath containing 4.5 oz./gal. Zn, 10.3 oz./gal. NaOH and 13.4 oz./gal. NaCN in a 267 ml. Hull test cell.

The zinc electrodeposit on the Hull test panel was bright over the entire range of slightly above 0 to amps/ft.

TEST RUN NO. 63

Reaction product of monoethanolamine, aqueous formaldehyde of 37 percent formaldehyde concentration, glycerol dichlorohydrin and nicotinic acid, in amount of l k ml., was added to an alkaline aqueous full or high cyanide zinc electroplating bath containing 4.5 oz./gal Zn, 10.3 oz./gal. NaOH and 13.4 oz./gal. NaCN in a 267 ml. l-lull test cell.

The zinc electrodeposit on the Hull test panel was bright over the entire range of slightly above 0 to 100 amps/ft.

TEST RUN NO. 64

Reaction product of monoethanolamine, aqueous formaldehyde of 37 percent formaldehyde concentration, glycerol dichlorohydrin and y-picoline, in amount of 1 9% ml., was added to an alkaline aqueous full or high cyanide zinc electroplating bath containing 4.5 oz./gal. Zn, 10.3 oz./gal. NaOH and 13.4 oz./gal. NaCN in a 267 ml. Hull test cell.

The zinc electrodeposit on the Hull test panel was bright over the entire range ofslightly above 0 to 100 amps/ft.

TEST RUN NO. 65

Reaction product of monoethanolamine, aqueous formaldehyde of 37 percent formaldehyde concentration, glycerol monochlorohydrin, and nicotinic acid, in amount of A ml., was added to an alkaline aqueous full or high cyanide zinc electroplating bath containing 4.5 oz./gal. Zn. 10.3 oz./gal. NaOH and 13.4 oz./gal. NaCN in a 267 ml. Hull test cell.

The zinc electrodeposit on the Hull test panel was bright over the entire range of slightly above 0 to 100 amps/ft.

TEST RUN NO. 66

Reaction product of monoethanolamine, aqueous formaldehyde of 37 percent formaldehyde concentration, glycerol monochlorohydrin, and 'y-picoline, in amount of A ml., 'was added to an alkaline aqueous full or high cyanide zinc electroplating bath containing 4.5 oz./gal. Zn, 10.3 oz./gal. NaOH and 13.4 oz./gal. NaCN in a 267 ml. Hull test cell.

The zinc electrodeposit on the Hull test panel was bright over the entire range of slightly above 0 to 100 amps/ft? TEST RUN NO. 67

Reaction product of diethanolamine, aqueous formaldehyde of 37 percent formaldehyde concentration, and epichlorohydrin, in amount of k ml., was added to an alkaline aqueous full or high cyanide zinc electroplating bath containing 4.5 oz./gal Zn, 10.3 oz./gal. NaOH and 13.4 oz./gal. NaCN in a 267 ml. Hull test cell.

The zinc electrodeposit on the Hull test panel was cloudy in the range of from slightly above 0 to about 4 amps/ft and bright in the range of about 4 to 100 amps/ft.

The Test Runs No. s 56, 57, 59-66 show the good brightness and wide range of brightness provided by full cyanide, i.e. high cyanide content, alkaline zinc electrodepositing baths containing reaction product brighteners of the invention. The zinc deposits provided by the full cyanide zinc electrodepositing baths of Test Runs No. 58 and 67 containing as additive a reaction product not of this invention were bright over a narrower range than were zinc deposits from full cyanide electrodepositing baths containing reaction product brighteners of the present invention.

The term low cyanide" content used herein with reference to the alkaline zinc cyanide electrodepositing bath means such, a bath with a total cyanide content of up to 2.0 oz./gal. The terms full cyanide content or high cyanide content used herein in referring to the alkaline zinc electrodepositing bath means such a bath with a total cyanide content of 10.0 oz./gal. or higher.

What is claimed is:

1. An aqueous alkaline zinc electrodepositing bath comprising an aqueous alkaline solution containing a source of zinc ions and an effective amount, sufficient to yield a bright zinc electrodeposit, of a bath-soluble reaction product obtained by the reaction of a nitrogen heterocyclic compound with an acyclic amine having at least two-functional groups, formaldehyde, and an epihalohydrin wherein the halogen is chloro or bromo or a glycerol chlorohydrin at a reaction temperatureof from room temperature to reflux temperature inclusive.

ZQThe bath of claim 1 wherein'the bath is a low cyanide content bath having a total cyanide content of up to 2.0' oz./gal and wherein the nitrogen heterocyclic compound is of the formula I tion product, said additional reactant being an aromatic amine of the formula wherein R is -H, NH or[OH.

6. The'bath of claimS wherein the R is Nl-l 7. The bath of claim 2 wherein the nitrogen heterocyclic 13. The bath of claim 12 wherein the epihalohydrin is epichlorohydrin and the bath-soluble reaction product is obtained by slowly adding an aqueous formaldehyde solution to a mixture of the amine having at least two functional groups, the nitrogen heterocyclic compound and an-aqueous diluent while agitating the mixture, slowly adding the epichlorohydrin to the thus-obtained mixture while agitating the mixture whereby exothermic heat is liberated during the epichlorohydrin addition with an attendant rise in temperature of the mixture to about its reflux temperature, and refluxing the resulting mixture for a period of at least about 20 16. The bath of claim 1 wherein the bath is free of cyanide,

the quinoline is isoquinthe nitrogen heterocyclic compound reactant is selected from the groups consisting of 01-, [3- and -y-picolines, nicotinic acid, vmylpyrrdmes, halopyridines wherein the halogen is chloro or bromo, picolylamines, methylpyrazines and quinolines; and

the amine reactant having at least two functional groups is selected from the groups consisting of mono-, diand triethanolamine, hexamethylenediamine, hexamethylenetetramine, ethylenediamine, diethylenetriamine and tetraethylenepentamine.

17. The non-cyanide bath of claim 16 wherein the nitrogen heterocyclic compound is selected from the group consisting of 'y-picoline, nicotinic acid, 4-vinylpyridine, 2- chloropyridine, 4-picolylamine, 2-methylpyrazine and isoquinoline.

18. The bath of claim 1 wherein the nitrogen heterocyclic compound is Z-methyl pyrazine.

19. The bath of claim 1 wherein the nitrogen heterocyclic compound is'y-picoline and 2-methylpyri'zine.

20. An aqueous alkaline zinc electrodepositing bath comprising an aqueous alkaline solution containing a source of zinc ions and an efiective amount, sufficient to yield a bright .zinc electrodeposit, of a bath-soluble reaction product obtained by the reaction of a nitrogen heterocyclic compound selected from the group consisting of those of the formulae:

and a quinoline, wherein R is hydrogen, methyl, chloro, bromo, amino, cyano, vinyl, hydroxypropyl or COOM wherein M is hydrogen or a hydrophilic cation, R, is hydrogen or amino with the proviso that when R, is amino R is methyl, and R is hydrogen, methyl or COOM wherein M is hydrogen or a hydrophilic cation with an acyclic amine having at least two functional groups, formaldehyde, and an epihalohydrin of the formula wherein X is chloro or bromo or a glycerol chlorohydrin of the formula CH2(l3H-(|1H-z wherein at least one but not more than two Xs is hydroxy and the remaining non hydroxy Xs are chloro at a reaction temperature of from room temperature to reflux temperature inclusive, the reactants being reacted in proportions within the molar ranges of about 0.1-0.3 mole of the nitrogen heterocyclic compourid, about 0.5-1.5 mole of the amine having at least two functional groups, about 1.0-3.0 moles of the formaldehyde, and about 0.5-1.5 mole of the epihalohydrin or glycerol chlorohydrin.

21. The bath of claim 20 wherein the amine having at least two functional groups is monoethanolamine.

22. The bath of claim 21 wherein the epihalohydrin is epichlorohydrin.

23. The bath of claim 22 wherein the bath is a low cyanide content bath having a total cyanide content of up to 2.0

oz./gal. and the nitrogen heterocyclic compound is of the fornitrogen heterocyclic compound selected from the group conmula sisting of those of the formulae wherein R is hydrogen, methyl, chloro, bromo, amino, cyano, /N vinyl, hydroxypropyl or COOM wherein M is hydrogen or a hydrophilic cation and R is hydrogen or amino with the N proviso that when R is amino R is methyl. y

24. A method for the electrodeposition of bright zinc which comprises electrodepositing the zinc from an aqueous alkaline and a quinoline wherein R is hydrogen, methyl, chloro, zinc eiectrodepositing bath comprising an aqueous alkaline bromo, amino, cyano, vinyl, hydroxypropyl or -COOM solution containing a source of zinc ions and an effective WhereinMis hydrogen orahydrophilic cation, R is hydrogen amount, sufficient to yield a bright zinc electrodeposit, of a or amino with the proviso that when R, is amino R is methyl, bath-soluble reaction product obtained by the reaction of a and R2 i hydrogen, methyl or -COOM wherein M is nitrogen heterocyclic compound with an acyclic amine having hydrogen or a hydrophilic cation with an acyclic amin h i at least two functional groups, formaldehyde, and an at least two un ti nal groups, formaldehyde, and an epihalohydrin wherein the'halogen atom is chloro or bromo or pihalohydrin 0f the formula a glycerol chlorohydrin at a reaction temperature of from room temperature to reflux temperature inclusive.

25. The method of claim 24 wherein the epihalohydrin is 25 ClIP-CIICIIqX epichlorohydrin, and the bath-soluble reaction product is obtained by slowly adding an aqueous formaldehyde solution to a mixture of the amine having at least two functional groups, z gzag}: X is chloro or bromo or a glycerol chlorohydnn of the the nitrogen heterocyclic compound and an aqueous diluent while agitating the mixture, slowly adding the epichlorohydrin F E to the thus-obtained mixture while agitating the mixture X X X whereby exothermic heat is liberated during the i.

epichlorohydrin addition with an attendant rise in temperawherein at least one but not more than two X's is hydroxy and ture of the mixture to about its reflux temperature, and refluxthe remaining non hydroxy Xs are chloro at a reaction teming the resulting mixture for a period of at least about 20 3 5 perature of from room temperature to reflux temperature inminutes clusive, the reactants being reacted in proportions within the 26. A method for the electrodeposition of bright zinc which molar ranges of about 0.1-0.3 mole of the nitrogen heterocomprises electrodepositing the zinc from an aqueous alkaline Cyclic compound, about 0.5-1.5 mole of the amine having at zinc electrodepositing bath comprising an aqueous alkaline least two functional groups, about 1.0-3.0 moles of the forsolution containing a source of zinc ions and an effective 40 maldehyde, and about 0.5-l.5 mole of the epihalohydrin or amount, sufficient to yield a bright zinc electrodeposit, of a glycerol chlorohydrin. bath-soluble reaction product obtained by the reaction of a Patent No. 3 655 534 Dated 1- 11 I 1'q 72 Inventor(s) Marcis M. Kamne It is certified that error appears in the above-identified patent. and that said Letters Patent are hereby corrected as shown below:

Column 3', line 46, "the" (second occurrence) should read --that--. In TABLE 1, wherever recited, "F, Br" should read ..--F Br--; wherever recited, "V, Br" should read --V Br--; Test Run Number 18, "CH -CH -CH -CH" should read --CH -CH -CH -QH- Column 10, line 47, "ml." (second ocurrenoe) should be deleted.

Signed and sealed this 28th day of November 1972.

(SEAL) Attest:

. EDWARD M.FLET 1HER ,JR. I ROBERT GOT'I'S CHALK Attestlng Of-flcer Commissioner of Patents

Claims (25)

1. 2. The bath of claim 1 wherein the bath is a low cyanide content bath having a total cyanide content of up to 2.0 oz./gal. and wherein the nitrogen heterocyclic compound is of the formula wherein R is hydrogen, methyl, chloro, bromo, amino, cyano, vinyl, hydroxypropyl or -COOM wherein M is hydrogen or a hydrophilic cation and R1 is hydrogen or amino with the proviso that when R1 is amino R is methyl.
2. 3. The bath of claim 2 wherein the nitrogen heterocyclic compound is a picoline.
3. 4. The bath of claim 3 wherein the picoline is gamma -picoline.
4. 5. The bath of claim 4 wherein an additional reactant is reacted with the other reactants to form the bath-soluble reaction product, said additional reactant being an aromatic amine of the formula wherein R is -H, -NH2 or -OH.
5. 6. The bath of claim 5 wherein the R is -NH2.
6. 7. The bath of claim 2 wherein the nitrogen heterocyclic compound is a pyridine monocarboxylic acid.
7. 8. The bath of claim 7 wherein the pyridine carboxylic acid is nicotinic acid.
8. 9. The bath of claim 2 wherein the nitrogen heterocyclic compound is 4-picolylamine.
9. 10. The bath of claim 2 wherein the nitrogen heterocyclic compound is 2-chloropyridine.
10. 11. The bath of claim 2 wherein the nitrogen heterocyclic compound is 4-vinylpyridine.
11. 12. The bath of claim 1 wherein the bath-soluble reaction product is obtained by the reaction of the nitrogen heterocyclic compound with the amine having at least two functional groups, formaldehyde, and the epihalohydrin.
12. 13. The bath of claim 12 wherein the epihalohydrin is epichlorohydrin and the bath-soluble reaction product is obtained by slowly adding an aqueous formaldehyde solution to a mixture of the amine having at least two functional groups, the nitrogen heterocyclic compound and an aqueous diluent while agitating the mixture, slowly adding the epichlorohydrin to the thus-obtained mixture while agitating the mixture whereby exothermic heat is liberated during the epichlorohydrin addition with an attendant rise in temperature of the mixture to about its reflux temperature, and refluxing the resulting mixture for a period of at least about 20 minutes.
13. 14. The bath of claim 1 wherein the nitrogen heterocyclic compound is a quinoline.
14. 15. The bath of claim 14 wherein the quinoline is isoquinoline.
15. 16. The bath of claim 1 wherein the bath is free of cyanide, the nitrogen heterocyclic compound reactant is selected from the groups consisting of Alpha -, Beta - and gamma -picolines, nicotinic acid, vinylpyridines, halopyridines wherein the halogen is chloro or bromo, picolylamines, methylpyrazines and quinolines; and the amine reactant having at least two functional groups is selected from the groups consisting of mono-, di- and triethanolamine, hexamethylenediamine, hexamethylenetetramine, ethylenediamine, diethylenetriamine and tetraethylenepentamine.
16. 17. The non-cyanide bath of claim 16 wherein the nitrogen heterocyclic compound is selected from the group consisting of gamma -picoline, nicotinic acid, 4-vinylpyridine, 2-chloropyridine, 4-picolylamine, 2-methylpyrazine and isoquinoline.
17. 18. The bath of claim 1 wherein the nitrogen heterocyclic compound is 2-methyl pyrazine.
18. 19. The bath of claim 1 wherein the nitrogen heterocyclic compound is gamma -picoline and 2-methylpyrazine.
19. 20. An aqueous alkaline zinc electrodepositing bath comprising an aqueous alkaline solution containing a source of zinc ions and an effective amount, sufficient to yield a bright zinc electrodeposit, of a bath-soluble reaction product obtained by the reaction of a nitrogen heterocyclic compound selected from the group consisting of those of the formulae:
20. 21. The bath of claim 20 wherein the amine having at least two functional groups is monoethanolamine.
21. 22. The bath of claim 21 wherein the epihalohydrin is epichlorohydrin.
22. 23. The bath of claim 22 wherein the bath is a low cyanide content bath having a total cyanide content of up to 2.0 oz./gal. and the nitrogen heterocyclic compound is of the formula wherein R is hydrogen, methyl, chloro, bromo, amino, cyano, vinyl, hydroxypropyl or -COOM wherein M is hydrogen or a hydrophilic cation and R1 is hydrogen or amino with the proviso that when R1 is amino R is methyl.
23. 24. A method for the electrodeposition of bright zinc which comprises electrodepositing the zinc from an aqueous alkaline zinc electrodepositing bath comprising an aqueous alkaline solution containing a source of zinc ions and an effective amount, sufficient to yield a bright zinc electrodeposit, of a bath-soluble reaction product obtained by the reaction of a nitrogen heterocyclic compound with an acyclic amine having at least two functional groups, formaldehyde, and an epihalohydrin wherein the halogen atom is chloro or bromo or a glycerol chlorohydrin at a reaction temperature of from room temperature to reflux temperature inclusive.
24. 25. The method of claim 24 wherein the epihalohydrin is epichlorohydrin, and the bath-soluble reaction product is obtained by slowly adding an aqueous formaldehyde solution to a mixture of the amine having at least two functional groups, the nitrogen heterocyclic compound and an aqueous diluent while agitating the mixture, slowly adding the epichlorohydrin to the thus-obtained mixture while agitating the mixture whereby exothermic heat is liberated during the epichlorohydrin addition with an attendant rise in temperature of the mixture to about its reflux temperature, and refluxing the resulting mixture for a period of at least about 20 minutes.
25. 26. A method for the electrodeposition of bright zinc which comprises electrodepositing the zinc from an aqueous alkaline zinc electrodepositing bath comprising an aqueous alkaline solution containing a source of zinc ions and an effective amount, sufficient to yield a bright zinc electrodeposit, of a bath-soluble reaction product obtained by the reaction of a nitrogen heterocyclic compound selected from the group consisting of those of the formulae