U.S. patent number 3,855,085 [Application Number 05/369,815] was granted by the patent office on 1974-12-17 for acid zinc electroplating electrolyte, process and additive.
This patent grant is currently assigned to E. I. du Pont de Nemours and Company. Invention is credited to John Derek Rushmere.
United States Patent |
3,855,085 |
Rushmere |
December 17, 1974 |
**Please see images for:
( Certificate of Correction ) ** |
ACID ZINC ELECTROPLATING ELECTROLYTE, PROCESS AND ADDITIVE
Abstract
Bright zinc electroplates can be deposited from electrolytes
containing zinc chloride, ammonium chloride, and an addition agent
comprising a mixture of certain nonionic polyoxyethylene compounds,
certain ketones and certain carboxylic acids.
Inventors: |
Rushmere; John Derek
(Wilmington, DE) |
Assignee: |
E. I. du Pont de Nemours and
Company (Wilmington, DE)
|
Family
ID: |
23457048 |
Appl.
No.: |
05/369,815 |
Filed: |
June 14, 1973 |
Current U.S.
Class: |
205/314;
205/311 |
Current CPC
Class: |
C25D
3/22 (20130101) |
Current International
Class: |
C25D
3/22 (20060101); C25D 3/02 (20060101); C23b
005/12 (); C23b 005/46 () |
Field of
Search: |
;204/55R,55Y,43Z,44,DIG.2 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Kaplan; G. L.
Claims
I claim:
1. A composition for providing bright zinc electrode deposits which
comprises an aqueous acidic electrolyte composition containing at
least one zinc compound providing zinc ions for electroplating
zinc, a source of chloride ion, 0.05 to 20 g./l. of at least one
nonionic polyoxyethylene compound, 0.05 to 2 g./l. of at least one
ketone, and 0.05 to 20 g./l. of at least one carboxylic acid,
said polyoxyethylene compound being selected from compounds of the
formula: ##SPC2##
wherein n + m .gtoreq. 10, x = 1 or 2, derived from a reaction of
oxyethylene with a polyol selected from the group consisting of
2,4,7,9-tetramethyl-5-decyne-4,7 diol,
polyoxypropylene glycol of molecular weight at least about 900,
and
N,n,n',n'-tetrakis(polyoxypropylene glycol) ethylene diamine of
molecular weight at least about 500,
and wherein R is defined by the selected polyol;
said ketone being selected from the group consisting of
4-phenyl-3-buten-2-one,
4-(4-methoxyphenyl)-3-buten-2-one,
4-(3,4-dimethoxyphenyl)-3-buten-2-one,
4-(3,4-methylenedioxyphenyl)-3-buten-2-one, and
4-(2-furyl)-3-buten-2-one; and
said carboxylic acid being selected from the group consisting
of
benzoic acid,
cinnamic acid,
2-furylacrylic acid, and
nicotinic acid.
2. A composition according to claim 1 having a zinc metal content
within the range of about 30 to 60 g./l. with the zinc added as
zinc chloride, a total chloride ion content of about 150 to 190
g./l. with the chloride other than zinc chloride being added in the
form of ammonium chloride, a pH in the range of about 3.5 to 6.1,
the polyoxyethylene compounds being present in the range of about
0.05 to 20 g./l., the ketone being present in the range of about
0.05 to 2 g./l., and the carboxylic acid being present in the range
of about 0.05 to 20 g./l.
3. A composition according to claim 2 having a pH in the range of
about 5 to 6, a content of polyoxyethylene compounds in the range
of about 2 to 10 g./l., a ketone content of about 0.1 to 0.5 g./l.,
and a carboxylic acid content of about 1 to 6 g./l. wherein said
polyoxyethylene compounds are polyoxyethylene
2,4,7,9-tetramethyl-5-decyne-4,7 diol and said ketone is
4-phenyl-3-buten-2-one.
4. A composition according to claim 1 wherein the polyol is
2,4,7,9-tetramethyl-5-decyne-4,7 diol.
5. A composition according to claim 1 wherein the polyol is
polyoxypropylene glycol of molecular weight of at least 900.
6. A composition according to claim 1 wherein the polyol is
N,N,N',N'-tetrakis(polyoxypropylene glycol) ethylene diamine of
molecular weight at least about 500.
7. A composition according to claim 1 wherein said ketone is
4-phenyl-3-buten-2-one.
8. A composition according to claim 1 wherein said ketone is
4-(4-methoxyphenyl)-3-buten-2-one.
9. A composition according to claim 1 wherein said ketone is
4-(3,4-dimethoxyphenyl)-3-buten-2-one.
10. A composition according to claim 1 wherein said ketone is
4-(3,4-methylenedioxyphenyl)-3-buten-2-one.
11. A composition according to claim 1 wherein said ketone is
4-(2-furyl)-3-buten-2-one.
12. A composition according to claim 1 wherein said carboxylic acid
is benzoic acid.
13. A composition according to claim 1 in which the pH is in the
range of about 3.5 to 6.1.
14. A composition according to claim 1 wherein the zinc
concentration measured as metal is in the range of about 30 to 60
g./l., and the zinc is provided as zinc chloride.
15. A composition according to claim 1 wherein the bath has a total
chloride ion concentration of about 150 to 190 g./l., with the
major portion of the chloride being provided as zinc chloride and
ammonium chloride.
16. A composition according to claim 1 wherein the polyoxyethylene
compounds are present in a concentration range of about 2 to 10
g./l.
17. A composition according to claim 1 wherein the ketone is
present in concentration range of about 0.1 to 0.5 g./l.
18. A composition according to claim 1 wherein the carboxylic acid
is present in a concentration range of about 1 to 6 g./l.
19. A method of producing bright zinc electrodeposits which
comprises passing current from an anode to a cathode at a
temperature about in the range of 15.degree. to 40.degree.C.
through an aqueous acidic electrolyte composition containing at
least one zinc compound providing zinc ions for electroplating
zinc, a source of chloride ion, 0.05 to 20 g./l. of at least one
nonionic polyoxyethylene compound, 0.05 to 2 g./l. of at least one
ketone, and 0.05 to 20 g./l. of at least one carboxylic acid,
said polyoxyethylene compound being selected from compounds of the
formula ##SPC3##
wherein n + m .gtoreq. 10, x = 1 or 2, derived from a reaction of
oxyethylene with a polyol selected from the group consisting of
2,4,7,9-tetramethyl-5-decyne-4,7 diol,
polyoxypropylene glycol of molecular weight at least about 900,
and
N,n,n',n'-tetrakis(polyoxypropylene glycol) ethylene diamine of
molecular weight at least about 500,
and wherein R is defined by the selected polyol;
said ketone being selected from the group consisting of
4-phenyl-3-buten-2-one,
4-(4-methoxyphenyl)-3-buten-2-one,
4-(3,4-dimethoxyphenyl)-3-buten-2-one,
4-(3,4-methylenedioxyphenyl)-3-buten-2-one, and
4-(2-furyl)-3-buten-2-one; and
said carboxylic acid being selected from the group consisting
of
benzoic acid,
cinnamic acid,
2-furylacrylic acid, and
nicotinic acid.
20. A method of claim 19 operated at temperatures in the range of
15.degree. to 40.degree.C. with a zinc metal content within the
range of about 30 to 60 g./l., the zinc being added as zinc
chloride, a total chloride ion content of about 150 to 190 g./l.
with the chloride other than zinc chloride being added in the form
of ammonium chloride, a pH in the range of about 3.5 to 6.1, the
polyoxyethylene compounds being present in the range of about 0.05
to 20 g./l., the ketone being present in the range of about 0.05 to
2 g./l., and the carboxylic acid being present in the range of
about 0.05 to 20 g./l.
21. A method of claim 20 having a pH in the range of about 5 to 6,
a content of polyoxyethylene compounds in the range of about 2 to
10 g./l., a ketone content of about 0.1 to 0.5 g./l., and a
carboxylic acid content of about 1 to 6 g./l. wherein said
polyoxyethylene compounds are polyoxyethylene
2,4,7,9-tetramethyl-5-decyne-4,7 diol and said ketone is
4-phenyl-3-buten-2-one.
22. A method of claim 19 wherein the pH is in the range of about
3.5 to 6.1.
23. A method of claim 19 wherein the zinc concentration measured as
metal is in the range of about 30 to 60 g./l., and the zinc is
provided as zinc chloride.
24. A method of claim 19 wherein the bath has a total chloride ion
concentration of about 150 to 190 g./l., with the major portion of
the chloride being provided as zinc chloride and ammonium
chloride.
25. A method of claim 19 wherein the polyoxyethylene compounds are
present in a concentration range of about 2 to 10 g./l.
26. A method of claim 19 wherein the ketone is present in a
concentration range of about 0.1 to 0.5 g./l.
27. A method of claim 19 wherein the carboxylic acid is present in
a concentration range of about 1 to 6 g./l.
28. An organoaqueous addition agent for use in preparing an acid
zinc electroplating bath composition, said addition agent
comprising:
10 to 400 g./l. of at least one nonionic polyoxyethylene compound
selected from the group consisting of ##SPC4##
wherein n + m .gtoreq. 10, x = 1 or 2, derived from a reaction of
oxyethylene with a polyol selected from the group consisting of
2,4,7,9-tetramethyl-5-decyne-4,7 diol,
polyoxypropylene glycol of molecular weight at least about 900,
and
N,n,n',n'-tetrakis(polyoxypropylene glycol) ethylene diamine of
molecular weight at least about 500,
and wherein R is defined by the selected polyol;
10to 200 g./l. of a ketone selected from the group consisting
of
4-phenyl-3-buten-2-one,
4-(4-methoxyphenyl)-3-buten-2-one,
4-(3,4-dimethoxyphenyl)-3-buten-2-one,
4-(3,4-methylenedioxyphenyl)-3-buten-2-one, and
4-(2-furyl)-3-buten-2-one; and
10 to 200 g./l. of a carboxylic acid selected from the group
consisting of
benzoic acid,
cinnamic acid,
2-furylacrylic acid, and
nicotinic acid.
29. An addition agent according to claim 28 wherein the
polyoxyethylene compounds are polyoxyethylene
2,4,7,9-tetramethyl-5-decyne-4,7 diols, the ketone is
4-phenyl-3-buten-2-one, and the carboxylic acid is benzoic
acid.
30. An addition agent according to claim 29 containing 20 to 50
g./l. of the polyoxyethylene compounds, 20 to 50 g./l. of the
ketone, and 20 to 50 g./l. of the carboxylic acid.
Description
BACKGROUND OF THE INVENTION
This invention relates to the deposition of bright zinc
electroplate, and more particularly to the electrodeposition of
such plate from acid electrolytes.
It is presently recognized that there are certain advantages to
being able to plate bright zinc electrodeposits from acid rather
than conventional basic cyanide baths. These advantages include the
ability to plate cast iron and carbonitrided steel as well as the
avoidance of problems associated with the disposal of toxic cyanide
wastes. Thus, a number of processes have been proposed recently for
electroplating bright zinc from acid baths which do not contain
cyanides.
In operating such acid zinc processes, certain additives are
required to obtain bright plate over a commercially operable range
of current densities and improved processes, and additives are
always desirable to extend this range of operating current
densities thus permitting more flexibility in plating, especially
in the plating of objects with complex surface configurations.
Certain polyoxyethylene compounds and certain ketone compounds have
been proposed for use in bright acid zinc electroplating, usually
in combination with other additives. For example, U.S. Pat. No.
3,594,291 -- Todt et al. describes the use of certain ketones with
N-polyvinyl pyrrolidone as brighteners in such baths, although the
plate produced is not truly bright at high current densities. U.S.
Pat. No. 3,694,330 -- Korpiun et al. and generally corresponding
British Pat. No. 1,149,106 disclose the use, along with an aromatic
carbonyl compound and ammonium chloride, of a nonionogenic, surface
active polyoxyethylene compound. Suitable aromatic carbonyl
compounds are said to include carboxylic acids, carboxylic acid
esters, aldehydes and ketones. However, the disclosures do not
teach the combined use of both carboxylic acids and ketones but
rather the use of them individually as equivalents. The bright
plating range is also limited to 10 to 50 a./ft..sup.2, although
the range below 10 a./ft..sup.2 is particularly desirable for
commercial barrel plating operations.
U.S. Pat. No. 3,669,854 -- Harbulak teaches bright acid zinc
electroplating using as additives polyethers and at least one
nonaromatic .alpha.,.beta.-unsaturated carbonyl compound. Harbulak
also discloses the use of citric acid as a bath component in
addition to the polyoxyethylene compound and a ketone. However, the
function of the citric acid is that of a complexing agent rather
than that of a brightener. The citric acid maintains the zinc in
solution at pH's above 5.5, preventing the precipitation of
insoluble zinc salts.
SUMMARY OF THE INVENTION
The present invention, in certain of its embodiments, provides
compositions for acid zinc electrolytic plating baths and additives
for such baths, as well as methods for using such baths.
The plating bath compositions of the invention comprise an aqueous
bath composition containing at least one zinc compound providing
zinc ions for electroplating zinc, a source of chloride ion, at
least one nonionic polyoxyethylene compound, at least one ketone,
and at least one carboxylic acid, wherein
said polyoxyethylene compound is selected from compounds of the
formula ##SPC1##
wherein n + m .gtoreq. 10, x = 1 or 2, derived from a reaction of
oxyethylene with a polyol selected from the group consisting of
2,4,7,9-tetramethyl-5-decyne-4,7 diol,
polyoxypropylene glycol of molecular weight at least about 900,
and
N,n,n',n'-tetrakis(polyoxypropylene glycol) ethylene diamine of
molecular weight at least about 500,
and wherein R is defined by the selected polyol;
said ketone is selected from the group consisting of
4-phenyl-3-buten-2-one (benzalacetone),
4-(4-methoxyphenyl)-3-buten-2-one (anisalacetone),
4 ,(3,4-dimethoxyphenyl)-3-buten-2-one (veratralacetone),
4-(3,4-methylenedioxyphenyl)-3-buten-2-one (piperonalacetone),
and
4-(2-furyl)-3-buten-2-one (furfuralacetone); and
said carboxylic acid is selected from the group consisting of
benzoic acid,
cinnamic acid,
2-furylacrylic acid, and
nicotinic acid.
The polyoxyethylene - 2,4,7,9-tetramethyl-5-decyne-4,7 diol is sold
under the name "Surfynol" by Air Products and Chemicals, Inc., of
Wayne, Pa. The polyoxyethylene - polyoxypropylene glycol is sold
under the name "Pluronic" by BASF Wyandotte Corp. of Wyandotte,
Michigan. The polyoxyethylene-N,N,N',N'-tetrakis(polyoxypropylene
glycol) ethylene diamine is sold under the name "Tetronic" by BASF
Wyandotte Corp.
The bath is preferably operated at a pH between 3.5 and 6.1. The
preferred pH range for optimum brightness and operability is 5 to
6. Zinc deposits of acceptable commercial quality can be obtained
over the temperature range of 15.degree. to 40.degree.C., and the
preferred operating temperature range is 20.degree. to 35.degree.C.
The preferred range of zinc metal content in the bath is 30 to 60
g./l., preferably added as zinc chloride. For best results, the
bath should have a total chloride ion content of 150 to 190 g./l.,
with the major portion (over 50% by weight) of the chloride, other
than that derived from zinc chloride, added in the form of ammonium
chloride.
The concentration ranges of the brightening additives in the bath
are as follows: polyoxyethylene compounds 0.05 to 20 g./l.,
preferably 2 to 10 g./l., ketone: 0.05 to 2 g./l., preferably 0.1
to 0.5 g./l.; carboxylic acid: 0.05 to 20 g./l., preferably 1 to 6
g./l. In the addition agent of the invention used to prepare and
maintain the baths, the concentration ranges of the brightening
additives are: polyoxyethylene compounds: 10 to 400 g./l.,
preferably 20 to 50 g./l.; ketone: 10 to 200 g./l., preferably 20
to 50 g./l.; carboxylic acid: 10 to 200 g./l., preferably 20 to 50
g./l .
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
It has been found that by using both the polyoxyethylene compounds
of the invention and the ketones of the invention in the presence
of certain carboxylic acids, the bright plating current density
range is considerably extended over that obtained when either the
carboxylic acid or ketone compounds are omitted, in accordance with
certain of the teachings of the prior art. Preferably two or more
different molecular weights of the polyethylene compounds of the
invention are used at the same time to obtain the most beneficial
results and widest bright plating range.
The operating pH of the bath is established at about 3.5 to 6.1
because at a pH much below 3.5 undesirable dissolution of zinc
anodes occurs even without electrolysis, and at a pH much above 6.1
precipitation of insoluble zinc salts commences. In operation, the
bath tends to seek its own pH level of about 5.8 to 6.1, and lower
pH levels can be maintained only by periodic additions of acid. The
higher pH is also desirable in that it minimizes corrosion effects
on plated parts due to poor rinsing.
While baths can be operated with the zinc metal content outside the
preferred range of 30 to 60 g./l., such conditions are less
preferred due to decreasing cathode efficiencies at lower zinc
concentrations and increasing low current density dullness at
higher concentrations.
The preferred range for total chloride ion content of 150 to 190
g./l. is arrived at from a recognition of the fact that baths
containing lower concentrations of chloride, while operable, have
the disadvantages of poorer low current density operation, poorer
anode corrosion, and a tendency to precipitate insoluble zinc salts
at pH's much above 5.5.
It should be recognized that bath formulations may also contain
other metal salts such as, for example, potassium sulfate or sodium
sulfamate. However, there appears to be little practical advantage
to using such materials. Bath formulations may also contain
mixtures of zinc salts such as zinc sulfate along with the zinc
chloride. Again, there appears to be little or no practical
advantage to this, and the preferred range of chloride content of
the bath should still be met. If no zinc chloride is used, this
chloride should come primarily from ammonium chloride. Alternative
sources of zinc include zinc oxide dissolved in common industrial
acids such as hydrochloric, sulfuric, acetic, fluoboric, and
sulfamic acids. Alternatively, aqueous solutions of commercial zinc
salts themselves may be employed, and, as mentioned above, zinc
chloride is preferred.
The pH of the bath is adjusted to the desired level by means of
addition of ammonium hydroxide, sodium hydroxide or equivalent
materials.
The zinc electrode deposits obtained from such acid baths are
typically coarse and dull in appearance and have little commercial
value until other additives are used. The additive of the invention
including certain nonionic polyoxyethylene compounds, certain
ketones, and certain carboxylic acids, each component added to the
bath in suitable amounts, permits the production of a bright, shiny
zinc electrodeposit of a high decorative quality over a wide range
of operating current densities and in a higher pH range than taught
by the prior art. As discussed above, the higher pH range is
desirable.
Brightener chemicals are preferably added to the bath as two types
of additives in order to obtain the correct balance of components
for initial start up and subsequent continued maintenance of the
bath under optimum conditions of performance.
A starter additive is usually used only once at the start as a new
bath is made up. It comprises an aqueous solution containing:
polyoxyethylene compounds: 100 to 500 g./l., preferably 200 to 350
g./l.; and carboxylic acid (added as sodium, potassium, ammonium or
similar salts) 50 to 250 g./l., preferably 100 to 200 g./l.
A maintenance additive is added initially to the bath and then on
demand to maintain performance. It comprises an organoaqueous
solution containing: polyoxyethylene compounds 10-400 g./l.
preferably 20 to 50 g./l.; carboxylic acid (as sodium, potassium,
ammonium or similar salt) 10-200 g./l. preferably 20 to 50 g./l.;
and ketone 10 to 200 g./l., preferably 20 to 50 g./l. In the
maintenance additive, methanol is used to solubilize the sparingly
soluble ketones of the invention. The amount of methanol required
varies depending on the concentration of ketone used in the
formulation, but typically may comprise 30 to 50 percent by weight
of the formulation. In place of methanol other inexpensive organic
solvents such as ethanol, acetone and the like may be employed.
In practicing the invention in the start up of a new bath, the
desired amount of starter additive, typically 10 to 40 cc. per
liter of bath, is added to the bath and well mixed. Next the
desired amount of maintenance additive typically 10 to 40 cc. per
liter of bath is added to the bath and well mixed. The bath is now
ready for operation.
To illustrate the operation of the invention and its superiority
over the prior art, the experiments were performed which are set
forth in the following examples. In the examples, an aqueous bath
containing 75 g./l. ZnCl.sub.2, and 185 g./l. NH.sub.4 Cl was used.
The temperature of operation was about 20.degree.C. The pH and
other parameters, and the additives used and their concentrations
are stated in the examples, and the resulting characteristics of
plates at various current densities are set forth. For the
polyoxyethylene compounds, the approximate molar content of the
polyoxyethylene is given.
EXAMPLE 1
Demonstrating Advantages of Three-Component Addition. Carboxylic
Acid Omitted in First Test
Test 1: To 1 liter of zinc chloride/ammonium chloride bath, at pH
5.0, were added: (polyoxyethylene).sub.10 mol tetramethyl decyn
diol ("Surfynol 465") 2.0 g. (polyoxyethylene).sub.30 mol
tetramethyl decyn diol ("Surfynol 485") 2.0 g. benzalacetone 0.2
g.
267 ml. of this solution were transferred to a Hull cell and a
steel cathode panel plated at 2 amps for 10 minutes. The panel
showed the following plate characteristics:
0-10 a./ft..sup.2 dull, gray black 10-14 a./ft..sup.2 bright 14-20
a./ft..sup.2 dull, gray 20-55 a./ft..sup.2 bright above 55
a./ft..sup.2 bright but very rough plate.
Test 2: To the same solution were next added 2 g. benzoic acid (as
sodium salt). A repeat 2 a./10 min. Hull cell panel test now
showed:
0-80 a./ft..sup.2 very bright Above 80 a./ft..sup.2 very bright but
some roughness.
EXAMPLE 2
Demonstrating Advantages of Three-Component System Carbonyl
Compound Omitted in First Test
Test 1: To 1 liter of zinc chloride/ammonium chloride bath, at pH
5.5, were added:
(polyoxyethylene).sub.10 mol tetramethyl decyn diol 2.0 g.
(polyoxyethylene).sub.30 mol tetramethyl decyn diol 2.0 g. benzoic
acid (as sodium salt) 2.0 g.
A steel cathode panel plated at 2 amps for 10 minutes in a 267 ml.
Hull cell showed the following plate characteristics:
0-1 a./ft..sup.2 dull, gray 1-35 a./ft..sup.2 semibright above 35
a./ft..sup.2 dull, black.
Test 2: To the same solution were added 0.2 g. benzalacetone. A
repeat, 2 a./10 min., Hull cell panel now showed:
0-80 a./ft..sup.2 very bright above 80 a./ft..sup.2 semibright,
rough.
EXAMPLE 3
Operation at pH 6
To 1 liter zinc chloride/ammonium chloride bath at pH 6.0 were
added:
(polyoxyethylene).sub.10 mol tetramethyl decyn diol 2.0 g.
(polyoxyethylene).sub.30 mol tetramethyl decyn diol 2.0 g. benzoic
acid (as sodium salt) 2.0 g. benzalacetone 0.2 g.
A steel panel plated at 2 amps for 10 minutes in a 267 ml. Hull
cell gave:
0-75 a./ft..sup.2 bright above 75 a./ft..sup.2 semibright,
rough.
The brightness here was not quite that obtained in Examples 1 and
2. However, increasing the benzalacetone concentration to 0.3 g./l.
fully restored the brightness level.
EXAMPLE 4
To 1 liter zinc chloride/ammonium chloride bath at pH 5.3 were
added:
(polyoxyethylene).sub.30 mol tetramethyl decyn diol 8.0 g.
2-furanacrylic acid 5.0 g. furfuralacetone 0.4 g.
A steel cathode plated at 2 amps for 10 minutes in a 267 ml. Hull
cell gave:
0-60 a./ft..sup.2 very bright 60-100 a./ft..sup.2 semibright, rough
above 100 a./ft..sup.2 dull, black.
EXAMPLE 5
To 1 liter zinc chloride/ammonium chloride bath at pH 5.4 were
added:
(polyoxyethylene).sub.205 mol (polyoxypropylene glycol).sub.39 mol
("Pluronic F 88") 2.0 g. benzalacetone 0.3 g. nicotonic acid 4.0
g.
A 267 ml. steel Hull cell cathode plated at 2 amps for 10 minutes
showed:
0-50 a./ft..sup.2 bright 50-60 a./ft..sup.2 dull 60-100
a./ft..sup.2 bright above 100 a./ft..sup.2 dull.
EXAMPLE 6
To 1 liter zinc chloride/ammonium chloride bath at pH 5.1 were
added:
(polyoxyethylene).sub.22 mol (polyoxypropylene glycol).sub.16 mol
("Pluronic L 35") 8.0 g. (polyoxyethylene).sub.10 mol tetramethyl
decyn diol 0.75 g. (polyoxyethylene).sub.30 mol tetramethyl decyn
diol 0.75 g. furfural acetone 1.5 g. nicotinic acid 1.0 g.
A steel Hull cell panel plated at 2 amps for 10 minutes gave a
deposit which was brilliant over the current density range 0-120
a./ft..sup.2 except for some roughness and a few dull vertical
streaks in the range 70-90 a./ft..sup.2
EXAMPLE 7
To 1 liter zinc chloride/ammonium chloride bath at pH 5.1 were
added:
(polyoxyethylene).sub.210 mol N,N,N',N'-tetrakis(poly- propylene
glycol).sub.46 mol ethylene diamine ("Tetronic 707") 4 g. benzoic
acid 4 g. benzalacetone 0.2 g.
A steel Hull cell panel plated at 2 amps for 10 minutes gave a
bright zinc deposit over the range 0-60 a./ft..sup.2
EXAMPLE 8
A 105 liter zinc chloride/ammonium chloride bath at pH 5.9 was
prepared. To it as brightener were added:
(polyoxyethylene).sub.10 mol tetramethyl decyn diol 2.0 g./l.
(polyoxyethylene).sub.30 mol tetramethyl decyn diol 2.0 g./l.
benzoic acid (as sodium salt) 2.0 g./l. benzalacetone 0.2 g./l.
A variety of parts including nuts, bolts, washers, safety harness
clamps were barrel plated in a horizontal barrel for 20-30 minutes.
Loading varied from 900-1,800 grams and plating current from 20-45
amps. Bright, shiny, well-adherent zinc with good coverage in
recesses was obtained on all parts.
Various other parts -- radio speakers, radio chassis, chain, wheel
rims were rack plated in the same bath using average current
densities of 20-60 a./ft..sup.2 and air agitation. Again, bright,
shiny, well-adherent zinc with good coverage in recesses was
obtained on all parts.
* * * * *