CA1119997A

CA1119997A - Electrodeposition of zinc

Info

Publication number: CA1119997A
Application number: CA000300888A
Authority: CA
Inventors: Bento Dafonte; Hans G. Creutz (Deceased); Roy W. Herr; Sylvia Martin
Original assignee: Oxy Metal Industries Corp
Current assignee: Oxy Metal Industries Corp
Priority date: 1977-05-04
Filing date: 1978-04-11
Publication date: 1982-03-16
Also published as: DE2819161A1; NL7804809A; DE2819161C2; JPS5628997B2; NL185359B; AU519624B2; NL185359C; FR2389688A1; JPS53137833A; FR2389688B1; GB1603446A; AU3572678A

Abstract

U 10,715/BFC:au ELECTRODEPOSITION OF ZINC

ABSTRACT OF THE DISCLOSURE

The instant invention is directed to an aqueous alkaline zinc-electroplating bath and to a process of utilizing the same, the bath comprising a source of zinc ions, and an effective zinc brightening amount of a bath soluble multiple quaternary compound which is the reaction product of a polyalkylene amine having a molecular weight of from about 60 to 1000, and an organic quater-nary ammonium halide which contains a halogen which will react with at least one-fourth of the available amino groups in the polyalkylene amine.

Description

U 10,71S

B~CK~ROUND OF TH~ INV~NTION
It is known in the art to which this invention pertains to provide an electroplating bath useful for the electrodeposition of zinc, comprising an alkaline electrolyte preferably containing aIkal;
rnetal zincate and also containing a reaction product of a poly-alkylene imine having a molecular ~eight from about 300 to 1,000,000 and an organic quaternary ammonium halide which contains a halogen which will quaternize a nitrogen of the polyalkylene imine in a ratio of one mole of organic ammonium halide to two mole-units of the poly-alkylene imine. A composition of this character is specifically disclosed in U.S. Patent No. 3,853,718 dated December 10, 1974, and which is assigned to the assignee of the instant application.
While the inventive concept described in the mentioned patent has fulfilled a need long existing in the art, the instant applicants have discovered that substantially improved results by way of plating solution stability as well as ductility and bright-ness of the zinc deposits are achieved by utilization in the bath of a small chain reaction product of a polyalkylene amine having a molecular ~eight in the range of 60 to 1000, and an organic ammonium halide containing a halide capable of quaternizing or alkylating a nitrogen of the polyalkylene amine so as to produce a plurality o~ nitrogcn qu~ternary sites.
In general, the reaction procceds as ~ollows:

C~l ~C1 1 2~n N1 31n wllercin;
Rl = H, alkyl of 1-4 carbon atoms;
R2 = -OH, H, -COOH, alkyl of 1-4 carbo~ Atoms;

2~

.
R3 = H, alkyl, hydroxyalkyl, carboxyalkyl, alkoxy of 1-4 carbon atoms;
m = 0-4; and n = 1-24 .~
X--R--N~3 (Rq) ~

wherein:
X = halogen R4 a H, alkyl of 1-4 carbon atoms, or more specifically, I
~~ ~7 ' ' R~N~9 (R4) 3 I x~ : .
~ ~ _ ~-N~ ~----.- .~ .. _ Ix~ . ~
, R

wherein: 0~
R = CH2 - CH - CH2 R3, R4 and X are defined as above.
The resulting reaction product contains structural units as previously described.
DESCRIPTION QF THE PRE~ERRED EMBODIMEN'I`
Appl.icants' invention is directed to the electrodeposition of zinc accomplished by utilization of an electroplating bath incorporating therein a source of zinc ions perferably provided by zinc metal in the amount of about 2 to 50 grams per liter, and more U 10,715 specifically approximately 6 to 30 grams per liter, and a bath soluble multiple quaternary compound which is the reaction product, firstly, of a polyalkylene amine having a molecular weight of from about 60 to 1000, and secondly, an organic quaternary ammonium halide which contains a halogen capable o reacting with at least one-fourth of the available amino groups in the polyalkylene amine.
In accordance with this invention, the reaction product as thus formed in the bath is present in an amount ranging from about 5 milligrams to 10 grams per liter, and more specifically, 10 milli-grams to 4 grams per liter.
The present invention is of application to a wide variety of zinc electroplating bat~,including those ~hich are known in the art as zincate or essentially cyanide-free baths, and those commonly referred to as high to low cyanide-containing baths~ In zincate plating baths there is generally present an admixture of zinc oxide and caustic. The amount of al~ali metal hydroxide may range from about 50 to 200 grams per liter a and the source of zinc ions is as earlier indicated.
The processing parameters are such that normally atmospheric temperature and pressure are employed, although temperatures of up to 55C. may be used, and even more preferably about 15 to 45C.
The cathode current density may vary Erc~ about 5 to 100 amps.
p~r sq.t., w}lile the anode current density rallges from approximate-ly 5 to 35 amps. per Sq.~t.
The zinc brightening a~ent that may be elllployed in the present invention is one that employs as a reactant polyalkylelle amine. It is to be appreciated that the reaction product that is to be used as a zinc brightener in the instant invention is one that should be soluble in the aqueous alkaline system. The poly-alkylene amine that is utilized is a lo~er alkyl substitute of .

U 10,715 polyethylene amine, that is a polyethylene amine in which one or more of the hydrogens are substituted by a lower alkyl, such as a one to three carbon alkyl radical, such as methyl, ethyl, and n-propyl or isopropyl and including the substitution derivatives in which one or more alkyl hydrogens are replaced by a bath compati-ble organic radical, such as for example, carboxyl, esterified carboxyl, aldehyde, acetyl, ether carbonyl, and other bath compatible radicals, such as the hydroxy or amino radicals. It is particularly preferred that the polyalkylene amine be unsubstituted polyethylene amineswhich are generally available to the public.
The polyethylene amine can be expressed as the polymeriza-tion product of the compound of Formula I;
Il l2 HN -~CH - CH -~CH23~m ~ ~~n H

wherein:
Rl = H, alkyl of 1-4 carbon atoms;
R2 = -OH, H, -COOH, alkyl of 1-4 carbon atoms;
R3 = H, alkyl, hydroxyalkyl, carboxyalkyl, alkoxy of 1-4 carbon atoms;
m = 0-4; and n = 1-24.
The polyalkylene aminc, preEerably ullsubstitlltcd polyethylene amine, may range from about 60 to 1000 in molecular ~eig}lt, and here;n lies an important patentable distinction over the disclosurc in commonly assigned U.S. Patent No. 3,853,718 to which rCel`ellCe was carlier made. As was mentioned previollsly, by proceeding in accordance ~ith the instant inve~ion, markedly improved results by ~ay of plating solution stability, as ~ell as ductility and brightness of th~ zinc deposits are achieved by utilization in the '~' ~ -5-10,715 bath of a small chain reaction product of a polyalkylene amine having a molecular weight in the range of 60 to 1000.
The zinc brightening agent that is to be employed in the present case preferably has a plurality of nitrogen quaternary ammonium sites. One of the quaternaries is in the repeating polyalkylene amine unit, while the side chain attached to the quaternary of the polyalkylene amine would be the second site or a quaternary nitrogen. The multiple nitrogen quaternary that may be employed herein is one that may be obtained by reacting the compound of Formula II;
X -R- N~ (R4)3 X~
with the aforementioned polyalkylene amine, wherein R may be OH
-CH2 - CH - CH2 ~ R4 may have up to 4 carbon atoms per R4 group, and X is a halogen.
A more specific formula representative of that defined immediately above is;
OH
Cl - CH2 - CH -CH2- N (~H3)3 Cl~
When one quaternizes the nitrogen of Formula I polymer-ization products with the compound of Formula II, there are obtained ploducts having some structrual units of Formula III;
- 0~3 C~l2 -Cll Cl-l2 N (C~l3)3 I Cl~
- N~
l3 Cl~

As can be appreciated, other agents may be l)rescnt in the bath in ordcr to impart other desirable characteristics such ~s improving the throwing powcr o~ the bath to low currcnt density i,. ~

.

U 10,715 areas, and improving the bath solubility of the components. Suit-able agents are anisaldehyde, glue, polyvinyl alcohol and the gly-cerol esters of polyvinyl alcohols having a molecular weight of 5,000 to 20,000. Other polymers that may be employed are gelatin, peptone and the like. In addition, chelating atents, or agents that can form a complex ~Yith the zinc in the bath may also be utilized, such as nitrilo triacetic acid and the various alkali metal salts, such as the sodium salt, ethylene diamine tetra acetic acid, and its water soluble salts, such as sodium and the like.
As has been indicated above, the novel concepts of this invention are applicable to cyanide-free or zincate baths as well as to cyanide-contsining zinc baths, and in the examples now to follow there will be set forth test data on both types of baths.
Generally stated, there is provided in an aqueous alXaline zinc electroplating bath a source of zinc ions and an effective zinc brightening amount of a bath soluble multiple quaternary compound which is the reaction product of a polyalkylene amine having a molecular weight of from about 60 to 1000, and an organic quaternary ammonium halide which contains a halogen which will react with at least one-fourth of the available amino groups in the poly-alkylene amine. More specifically, the source of zinc ions is preferably provided by zinc metal in the amount of about 2 to 50 grams per liter, and to be more precise, approximately 6 to 30 ~rams per liter, and a reaction product as herein defined wllich is present in the bath in an amount ranging from about 5 milligrams to 1~ grams per liter, and more particularly, 10 millig`rams to 4 grams per liter.
The invention will be more fully understood when reference is made to the following examples, the first two and the test data flowillg therefrom being directed to a zincate or cyanide-frec bath.

U 10,715 EXAMPL~ I
A solution of 5.7 mole o te~raethylene pentamine was reacted with 14.7 mole N-(3-chloro-2-hydroxypropyl) trimethyl ammonium chloride in the presence of 300 grams of sodium hydroxide.
The solution was refluxed for 1 hour. The product obtained was then mixed in the amount of 2 g/l with lOg/l of zinc oxide and 100 g/l of sodium hydroxide. Using a conventional Hull cell with the above described plating solu~ion maintained at a temperature of about 70F., steel panels measuring approximately 3 by 5 inches were plated in the bath just described for about ten minutes at 2 amperes. I'he zinc deposit obtained was uniform and semi-bright.

~.
EXAMPLE II
A solution of 1 mole triethylene tetramine containing 250 grams sodium hydroxide was reacted with 3 moles of N-~3 bromo-2 hydroxy propyl) trimethyl ammonium bromide by refluxing for one hour. The resulting product was mixed in the quantity of 4 g/l with 10.5 g/l of zinc metal and 90 g/l of sodium h~droxide. Plating was accomplished in a Hull cell at about 80F. for approximately 10 minutes at one ampere. An even, semi-bright zinc deposit was obtained.

F.XAMPLE III
The resulting product obtained from the two s~arting in~redients mentioned in Example I was mixed in the amount oE
0.5 g/l with 7.5 g/l o zinc metal, 120 g/l o~ sodium hydroxide and 10 mg/l of betaine o~ benzyl chloride and nicotinic acid, Again in a Hull cell maintained this time at about 90F. and a ~lating time of approximately ten minutes at 2 amperes, the zinc deposit obtained was observed to be lustrous over a wide current density range.

EXAMPLE IV
The resulting product obtained from the reaction o~
the two starting ingredients set forth in Example II was mixed in the amount of 1 g/l with 6 g/l of zinc metal, 80 g/l of sodium hydroxide and 100 mg/l of anisaldehyde bisulfite. Under conditions in a Hull cell of about 75F. and a plating time of approximately 10 minutes at 2 amperes, the bath of this example provided a zinc deposit lustrous up to 50 ASF and uniformly semi-bright above that range.
To illustrate the invention further, there will now be described work performed with a cyanide zinc bath embodying the novel concepts of this invention.
EXAMPLE V
To a solution containing 5.7 moles of tetraethylene pentamine there was added 14.7 moles of sodium hydroxide and 14.7 moles of N-~3-chloro-2-hydroxy propyl~ trimethyl ammonium ~: :
chloride. The solution was heated to 90. ~or one hour and allowed to cool overnight.
The resultant products were further formulated with a source of zinc ions and cyanide. The results thereof are set forth below.
~X~MPLE VI
The compound of Example V in the amount of 1.0 g/l was mixed with 34O0 g/1 of zinc metal, 75.0 g/l of sodium hydroxide, and 90.0 g/l oE sod:Lum cyanide~ In a Hull cell, at room temperature and with 2 amperes on test plates of the dimen-sions earlier indicated, there was obtained a zinc plate deposit which was bright below a~out 20 ASF and semi-bright above this value.
EXAMPLE VII

In a further formulation, the compound of Example V

~,~ .

'7 in the amount of 0.5 g/l was combined with 18~0 g/l of zinc metal, 75 g/l of sodium hydroxide and 45.0 g/l of sodium cyanide. Under room temperature conditions and 2 amperes in the cathode panel in a conventional Hull cell, the zinc deposit obtained was bright below 25 ASF and semi-bright thereabove.
ExAMæLE VIII
An additional formulation was prepared using the composition of Example V in the amount of 50 mg/l and zinc metal 7.5 g/l, sodium hydroxide 67 g/l, and sodiurn cyanide 11.0 g/1~
On test plates of the approximate dimensions earlier indicated, the zinc deposit obtained in a Hull cell under room temperature conditions with 2 amperes in the cathode, the deposit was bright below about 18 ASF and semi-bright above this curren-t density.
EXAMPLE IX

. _ The composition as prepared in accordance with Exarnple V was mi~ed in the amount of about 2.0 g/l with 11.5 g/l of zinc metal, 90.0 g/l of sodiurn hydroxide and 3.75 g/l of sodium cyanide. In a Hull cell the zinc deposit was bright below 35 ASF
and generally semi-bright above 35 ASF~ The deposi-t was plated at roorn temperature with 2 amperes on -the cathode.
As was stated hereinabove, one of the inventive contributions made by the instant applicants is the discovery that by utilizing a small chain reaction product of a poly-alkylene amine having a molecular weight in the range oE 60 to 1000 with an organic ammoniurn halicle containing a halide capable of q~aternizing or all~ylating a ni-trogen oE the polyal~ylene amine so as to produce a plurality oE nitrogen quaternary sites, there ~ achieved substantially improved results by way of plating solution stability as well as ductility and brightness of the zinc deposits. In order to more fully illustrate this advance over the inventive concept set forth in commonly assigned - 10 ~

~'4 ~:

3~7 Patent ~o. 3,853,718, the following comparative data was developed in an essentially cyanide-free zinc electroplating bath.
An alkaline zinc electroplating solution was prepared containing zinc metal in the amount of abou-t 6.8 g/l and approximately 80 g/l of sodium hydroxideO This solution was divided into two essentially equal portions and to Part (A) there was added 2 g/1 of a multi-nitrogen compound derived from a polyal~ylene imine having a molecular weight of about 100 9 000 and N-(3-chloro-2-hydroxy propyl) trimethyl arnmonium chloride.
To Part (B) there was added 2 g/l of a multi-nitrogen compound derived from a polyalkylene amine whose molecular weight was about 190~
In a conventional ~Iull cell, operated at approximately 70F., with 2 amperes on the cathode, the following results were obtained after 30 minutes on the normally used steel plates.
Both Part (A) and (B) under the conditions stated produced bright zinc deposits, however, the deposit o-f Part (A) was less ductile -than that obtained ~rom Part (B). On the other hand, after a lengthy period of plating and the addition of ]~nown brighteners to the solutions containing Parts (A) and (B), there was observed a tendency w:Lth solution (A) toward dullness in the high current density areas apparently due to interference of brea~-down products. In low c:urrent density areas, the Part (B) solution was more clear and of greater brigh-tness than that of solution (A).
Various changes and modiEications in the Eormulations herein disclosed and in the method of compounding the same may of course be practiced without departing from the spirit of the invention or the scope of the subjoined claims.

.

Claims

J 10,715 The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1) An aqueous alkaline zinc electroplating bath, comprising a source of zinc ions 9 and an effective zinc brightening amount of a bath soluble multiple quaternary compound which is the reaction product of a polyalkylene amine having a molecular weight of from about 60 to 1000, and an organic quaternary ammonium halide which contains a halogen which will react with at least one-fourth of the available amino groups in the polyalkylene amine.

2) A zinc electroplating bath as defined in Claim 1, in which the source of zinc ions is zinc metal present in the amount of about 2 to 50 grams per liter, and in which the reaction product is present in the bath in an amount ranging from about 5 milligrams to 10 grams per liter.

3) A zinc electroplating bath as defined in Claim 1, in which the source of zinc ions is zinc metal present in the amount of approxiamtely 6 to 30 grams per liter, and in which the reaction product is present in the bath in an amount of from about 10 milligrams to 4 grams per liter.

4) A zinc electroplating bath as defined in Claim 1, in which the polyalkylene amine has the formula:

wherein:
R1 = H, alkyl of 1-4 carbon atoms;
R2 = -OH, H, -COOH, alkyl of 1-4 carbon atoms;
R3 = H, alkyl, hydroxyalkyl, carboxyalkyl, alkoxy of 1-4 carbon atoms;
m = 0-4; and n = 1-24. 12

5) A zinc electroplating bath as defined in Claim 1, in which the organic quaternary ammonium halide has the formula:

wherein R may be is hydrogen or alkyl of 1 to 4 carbon atoms, and X is a halogen.

6) A zinc electroplating bath as defined in Claim 1, in which the polyalkylene amine has the formula:

wherein:
R1 = H, alkyl of 1-4 carbon atoms;
R2 = -OH, H, -COOH, alkyl of 1-4 carbon atoms;
R3 = H, alkyl, hydroxyalkyl, carboxyalkyl, alkoxy of 1-4 carbon atoms;
m = 0-4; and n = 1-24 and the organic quaternary ammonium halide has the formula:

wherein R may be is hydrogen or alkyl of 1 to 4 carbon atoms and X is a halogen.

7) A zinc electroplating bath as defined in Claim 6, in which the source of zinc ions is zinc metal present in the amount U-10,715 of about 2 to 50 grams per liter, and in which the reaction product is present in the bath in an amount ranging from about 5 milligrams to 10 grams per liter.

8) A zinc electroplating bath as defined in Claim 6, in which the source of zinc ions is zinc metal present in the amount of approximately 6 to 30 grams per liter, and in which the reaction product is present in the bath in an amount of from about 10 milligrams to 4 grams per liter.

9) A zinc electroplating bath as defined in Claim 1, in which the polyalkylene amine has the formula:

wherein:
R1 = H, alkyl of 1-4 carbon atoms;
R2 = -OH, H, -COOH, alkyl of 1-4 carbon atoms;
R3 = H, alkyl, hydroxyalkyl, carboxyalkyl, alkoxy of 1-4 carbon atoms;
m = 0-4; and n = 1-24 and the organic quaternary ammonium halide has the formula:

U 10,715

10) A zinc electroplating bath as defined in Claim 9, in which the reaction product has the formula:

wherein R3 is as defined above.

11) A zinc electroplating bath as defined in Claim 9, in which the source of zinc ions is zinc metal present in the amount of about 2 to 50 grams per liter, and in which the reaction product is present in the bath in an amount ranging from about 5 milligrams to 10 grams per liter.

12) A zinc electroplating bath as defined in Claim 9, in which the source of zinc ions is zinc metal present in the amount of approximately 6 to 30 grams per liter, and in which the reaction product is present in the bath in an amount of from about 10 milligrams to 4 grams per liter.

13) A method of depositing zinc from an aqueous alkaline zinc electroplating bath, which comprises passing an electric current from an anode through the bath of Claim 1 to a catholic workpiece for a period of time sufficient to form a zinc deposit.

14) A method of depositing zinc from an aqueous alkaline zinc electroplating bath, which comprises passing an electric current from an anode through the bath of Claim 9 to a cathodic workpiece for a period of time sufficient to form a zinc deposit, the temperature of said bath being between about 15°C. to 45°C., U 10,715 the cathode current density varying from about 5 to 100 amps. per sq.ft., and the anode current density being from about 5 to 35 amps. per sq. ft.