Note: Descriptions are shown in the official language in which they were submitted.
-`I 3L114~4~6
. KGW ( CASh 12 9 3 ) DC
: BRIGHT NICKEL ~LE;CTROPLATI~IG
Background of the Invention
.
To conserve nickel and reduce costs, a number of
prodecures have been adopted by the nickel plating industry.
Some of these procedures include reducing the thickness
of the nickel deposited, substituting cobalt for some or all
of the nic]~el when cobalt is less expensive or more readily
available, and more recently electrodepositing nickel-iron,
cobalt-iron, or nic~el-cobalt-iron alloys in which as much
as 6Q~ of the deposit may consist of relatively inexpensive
iron.
However, when deposit thickness is reduced, it
is necessary to use more effective or "powerful" nic]~el
brighteners or higher concentrations of nickel brighteners,
~ so that the degree of brightening and leveling to which the
; 15 nickel plating industry has grown accustomed may be obtained.
The more "powerful" nic~el brighteners or high concentrations
of brighteners, while capable of producing the desired
brightening and leveling, may nevertheless cause unacceptable
side effects. The deposits may peel or may be highly stressed,
severely embrittled, less receptive to subsequent chromium
deposits or exhibit hazes, reduced low current density covering
power or "throw'l or striations and skip plate i.e.; areas in
which a deposit is not obtained.
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In order to overcome the deleterious effects of
,~ "powerful" brighteners or high concentrations of briyhteners,
the addition of various sulfinic acids or their salts has been
recommended by Brown in U. S. Patent 2,654,703; the use of
organic hydroxy sulfonates has also been recommended by Passal
in U. S. Patent 3,697l391 for this purpose.
Unfortunately these compounds severely reduce the
deposit leveling and bright range.
Further attempts have been made to improve low current
density characteristics when "powerful" brighteners or high
concentrations of brighteners are used:
i) The use of aromatic monoamines, aromatic polyamines,
unsubstituted polyethylenepolyamine by Du Rose
in U. S. Patent 3,630,857.
ii) The use of N-(3-sulfopropyl) pyridinium inner salts
by Rosenberg in U. S. Patent 3,862,019.
iii) The use of N-disubstituted amino propyne or its
hydrochloride by Law in U. S. Patent ~,054,495.
While these compounds do improve low current density
characteristics, they still do not produce low current density
deposits which are free from darkness and skip plate.
It is an object of this nvention to provide processes
and compositions for depositing electrodeposits of nickel which
possess a greater tolerance for "powerful" brighteners and high
concentrations of brighteners. It is also an object of this
invention to accomplish this tolerance without affecting the
leveling of the deposits. It is further an object of this
invention to accomplish this tolerance while providing low
current areas free from darkness and skip plate without affecting
the bright range.
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Description of the Invention
In accordance with certain of its aspects this .invention rela~es
to a process and composition for the preparation of a nickel electrodeposit,
which comprises passing current from an anode to a cathode through an
aqueous acidic electroplating solution containing at least one member
- æ lected from nickel ccnlpounds; the improvement comprising the presence of
i) an acetylenic amine or substituted amine, aliphatic or
aromatic; and
ii) a sulfonated acetylenic and salts thereof where the acetylenic
bond and the sulfonate radical are connected by a carbon chain
where C = 1-6;
for a time period sufficient to fo~m a metal electroplate upon said cathode.
The concentrations of said ccmpounds may be:
` i) aoetylenic amine or substituted acetylenic amine, aliphatic or
aromatic - 0.005-0.1 g/l
ii) sulfonated aoetylenic acid and salts thereof - 0.005-0.25 g/l
with a preferred range of:
i) acetylenic amine or substituted acetylenic amine, aliphatic or
aromatic - 0.01-0.04 g/l
ii) sulfonated aoetylenic acid and salts thereof - 0.01-0.10 g/l.
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Examples of acetylenic amines and substituted acetylenic
amines of this invention, but not restricted to, are:
4-diethylamino-2-butyn-1-01
- 1,6-bis-(diethylamino)-2-hexyne
1-dimethylamino-2-propyne
N-methylpropargyl amine
propargyl amine
l-diethylamino-2-propyne
5-dimethylamino-2~methyl 3-pentyn-2-01
1-dimethylamino-2-pentyne
3-methylamino-1-butyne
l-dimethylamino-2-hexyne
l-dimethylamino-2-butyne
1-diethylamino-2-butyne
1-diethylamino-2-hexyne
: 4-diethylamino-1-butyne
4-diethylamino-2-pentyn-4-01
1,6-bis(morpholino)-2-hexyne
6-diethylamino-1-piperidino-2-hexyne
Examples of sulfonated acetylenics of this invention,
but not restricted to, are:
2-butyne-1,4-disulfonic acid
2-butyne sulfonic acid
propargyl sulfonic acid
l-butyne sulfonic acid
l-pentyne sulfonic acid
~1 ~134r)6
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mhe baths of this invention may also contain an
effective amount of at least one member selected from the group
consisting of:
(a) ~lass I brighteners
(b) Class II brighteners
.- (c) Anti-pitting or wetting agents
The term "Class I brighteners" as used herein, and
as described in ~lodern Electroplating, Third Edition,
F. Lowenheim, Editor, is meant to include aromatic sulfonates,
sulfonamides, sulfonir.ides, etc., as well as aliphatic or
aromatic-aliphatic olefinically unsaturated sulfonates,
sulfonamides, sulfonimides, etc. Specific examples of such
plating additives are:
. (1~ sodium o-sulfobenzimide
: 15 (2) disodium 1,5-naphthalene trisulfonate
. (3) trisodium 1,3,6-naphthalene trisulfonate
(~) sodium kenzene monosulfonate
. (5) dibenzene sulfonimide
. (6) sodium 3-chloro-2-butene-1-sulfonate
(7) sodium ~-styrene sulfonate
(8) monoallyl sulfamide
(9) diallyl sulfamide
. (10) allyl sulfonamide
Such plating additive compounds, which may be used
singly or in suitable combinations, are desirakly employed in
amounts ranging from about 0.5 to 10 grams per liter and provide
the advantages described in the above reference and which are
well known to those skilled in the art of nickel electroplating.
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The term "Class II brighteners" as used herein, and
as described in Modern ElectroplatincJ, mhird Edition,
F. Lowenheim, Editor, is meallt to include platin~ additive
compounds such as reaction products of epoxides with alphahydroxy
acetylenic alcohols such as diethoxylated 2-butyne-1,4~diol or
dipropoxylated 2-butyne-1,4-diol, other acetylenics,
N-heterocyclics, dye-stuffs, etc.
Specific examples of such plating additives are:
(1) 1,4-di-(3-hydroxyethoxy)-2-butyne
(2) l,4-di-(~-hydroxy- y-chloropropoxy)-2-butyne
(3) 1,4-di-(~-, y-epoxypropoxy)-2~butyne
(4) 1,4-di-(~-hydroxy- ~-butenoxy)-2-butyne
. (5) 1,4-di-(2'-hydroxy-4'-oxa-6'-heptenoxy)-2-buty e
(6) N-(2,3-dichloro-2-propenyl)-pyridinium chlorid
(7) 2,4,6-trimethyl N-propargyl pyridinium bromide
(8) N-allylquinaldinium bromide
(9) 2-butyne-1,4-diol
(10) propargyl alcohol
(ll) 2-methyl-3-butyn-2-ol
(12) quinaldyl-N-propanesulfonic acid betaine
(13) quinaldine dimethyl sulfate
: (14) N-allylpyridinium bromide
(15) isoquinaldyl-N-propanesulfonic acid betaine
: (16) isoquinaldine dimethyl sulfate
(17) N-allylisoquinaldine bromide
. (18) 1,4-di-(~-sulfoethoxy)-2-butyne
. (19) 3-(~-hydroxyethoxy) propyne
.. (20) 3-(~-hydroxypropoxy)-propyne
(21) 3-(~-solfoethoxy)-propyne
(22) phenosafranin
(23) fuchsin
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484~16
When used alone or in combination, desirably in amounts
ranging from about 5 to 1000 milligrams per liter, a Class II
brightener may produce no visual effect on the electrodeposit,
: or may produce semi-lustrous, fine-grained deposits. However,
best results are obtained when Class II brighteners are used
with one or more Class I brighteners in order to provide
optimum deposit luster, rate of brightening, leveling,
bright plate current density range, low current density
coverage, etc.
The term "anti-pitting or wetting agents" as used
~: herein is meant to include a material which functions to prevent
or minimize gas pitting. An anti-pitting agent, when used alone
or in combination, desirably in amounts ranging from about
0.05 to 1 gram per liter, may also function to ~.ake the baths
more compatible with contaminants, such as oil, grease, etc.
by their emulsifying, dispersing, solubilizing, etc. action
on such contaminants and thereby promote attaining of sounder
deposits. Preferred anti-pitting agents may include sodium
lauryl sulfate, sodium lauryl ether-sulfate and sodium
dial~ylsulfosuccinates.
The nickel compounds employed for electrodepositing
nickel are typically added as the sulfate, chloride, sulfamate,
or fluoborate salts. The sulfate, chloride, sulfamate and
fluoborate salts of nickel are employed in concentrations
sufficient to provide nickel in the electroplating solutions
of this invention in concentrations ranging from about
10 to 150 grams per liter.
11 ~84~6
The nickel electroplating baths of this invention
additionally may contain from about 30 to 60 grams per liter,
preferably about 45 grams per liter of boric acid or o'her
buffering agents to control the pH (e.g.; from a~out 3.5-4.5,
preferably 4O0) and to prevent high current density burning.
In order to prevent "~urning" of high current density
areas, and provide for more even temperature control of the
solution, solution agitation may be employed. Air agitation,
mechanical stirring, pumping, cathode rod and other means of
solution agita~ion are all satisfactory. Additionally,
the solutions may be operated without agitation.
The operating temperature of the electroplating baths
of this invention may range from about 40C to about 70C,
preferably from about 50C to 62C.
The average cathode current density may range from
about 0.5 to 12 amperes per square decimeter, with 3 to 6 amperes
per square decimeter providing an optimum range.
Typical aqueous nickel-containing electroplating
solutions (which may be used in combination with effective
amounts of cooperating additives) include the following
wherein all concentrations are in grams per liter (g/l)
unless otherwise indicated.
TABLE I
Aqueous Nickel-Containing Electroplating Solutions
Minimum~aximumPreferred
Component:
` NiSO4-6H2O 75 500 300
2-6H2 20 135 60
H3BC3 30 60 45
~ pH (ele rometric) 3.5 4.5 4.0
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During bath operation, the pH may nor~ally tend to
rise and may be adjusted with acids such as hydrochloric acid,
sulfuric acid, etc.
Anodes used in the above baths may be electrolytic
or sulfur containing nickel bars, strips or small chunks in
titanium baskets. All anodes are usually suitably covered
with cloth or plastic bags of desired porosity to miniMize
introduction into the bath of metal particles, anode slime,
etc. which May migrate to the cathode either mechanically or
electrophoretically to give roughness in cathode deposits.
The substrates on which the nickel electrodeposits
of this invention may be applied may be metal or metal alloys
such as are commonly electrodeposited and used in the art of
electroplating such as nickel, cobalt, nickel-cobalt, copper,
tin, brass, etc. Other typical substrate basis metals from
which articles to be plated are manufactured may include
ferrous metals such as iron, steel, alloy steels, copper,
tin and alloys thereof such as with lead, alloys of copper
such as brass, bronze, etc., zinc, particularly in the form
of zinc-base die castings; all of which ~ay bear plates of
otne^ metals, such as copper, etc. Basis metal substrates
may have a variety of surface finishes depending on the final
appearance desired, ~Ihich in turn depends on such factors
as luster, brilliance, leveling, thickness, etc. of the
nickei electroplate applied on such substrates.
While nickel electrodeposits can be obtained employing
the various parameters described above, the bri~htness, leveling,
ductility and covering power may not be sufficient or satisfactory
for a pa~ticular application. In addition the deposits may be
hazy or dull, and also exhibit striations, step plate, peeling,
poor bright range or poor chromium receptivity. These conditions
: may especially result after the addition of excessive replenish-
ment amounts of Class II brighteners, or from the use of
especially powerful Class II brighteners.
The addition or inclusion of specified amounts of
(i) an acetylenic amine, or
substituted acetylenic amine, aliphatic
or aromatic and
(ii) a sulfonated acetylenic compound and
salts thereof, where the acetylenic bond
and the sulfonate radical are connected
` by a carbon chain where C = 1-6
to an aqueous acidic nickel electroplating bath will correct
r the aforementioned deficiencies.
Additionally when used together, compounds from these
classes will permit the use of higher than normal concentrations
of Class II brighteners, thus permitting higher rates of
brightening and leveling without the undesirable striations,
skip plate, poor bright range, etc. normally expected under
~5 these conditions.
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Compounds from the two classes of this invention are
unusual in that they act synergistically together to produce
sound low current density deposits fxee from darkness,
striations, skip plate, etc. without affecting leveling or
the bright range of the electrodeposit in the presence of
"powerful" or high concentrations of Class II brighteners.
These compounds when used independent of one another and in
the presence of "powerful" or high concentrations of Class II
brighteners still produce electrodeposits exhibiting one or
more of the following effects: low current density darkness,
striations, skip plate, poor bright range.
The concentrations of the compounds in the invention
are:
i) acetylenic ar.~ine or substituted acetylenic
amine, aliphatic or aromatic - 0.005-0.1 g/l
ii) sulfonated acetylenic compound and salts
thereof, where the acetylenic bond and
the sulfonate radical are connected by
a carbon chain where C = 1-6, - 0.005-0.25 g/l
with the preferred concentrations being:
i) acetylenic amine or substituted acetylenic
- amine, aliphatic or aromatic 0.01-0.04 g/l
ii) sulfonated acetylenic compound and salts
thereof, when the acetylenic kond and the
sulfonate radical are connected by a carbon
chain where C = 1-6 0.01-0.10 g/l.
Lhe following examples are presented as an illustration
w ~h
to provide those skilled in the art of electroplatingj a ketter
understanding of the various embodiments and aspects of this
invention. These examples should not be construed as limiting
the scope of the invention in any way.
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11 4~4,36
TABLE II
; Compositions in g/1
Panel Panel Panel Panel Panel
1 _ 2 3 4 5
4 6 2 300 300 300 300 300
NiC12-6H2 60 60 60 60 60
H3sO3 45 45 45 45 45
pH 4.04.0 4.0 4.0 4.0
temperature 60C 60C 60C 60C 63C
sodium o-sulfobenzimide 1.35 1.35 1.35 1.35 1.3c
propargyl alcohol 0.005 OOOO' 0.00' 0.01 0.005
monoethox~lated propargyl 0.01 0.01 0.01 0.01 0.01
alcohol
l-diethylamino-2-propyne Nil 0.02 0.02C Nil 0.02
sodium salt of propargyl
sulfonic acid Nil 0.1 0.05 0.15 0.02
2-butyne-1,4-diol Nil Nil 0.02 Nil Nil
4-diethylami -2-pentyn-4-ol Nil Nil Nil ~ O.01~ Nil
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The conditions for plating the panels from the above
aqueous nickel electroplating compositions were as follows:
A zinc coated steel panel was stripped in 50% hydrochloric acid,
rinsed, and then scribed with a horizontal single pass of
4/0 grit emery polishing paper and 2 grit emery polishing paper.
The cleaned panel was then plated in a 267 ml Hu]l Cell using
the aforementioned compositions for 10 minutes at 2 amperes
cell current, using cathode rocker agitation.
OBS~RVATIONS:
Panel ~1 - shows a ductile deposit with fair brightness and
leveling, low current density darkness, skip plate,
hazing at 2-4 asf and a thin plate area at 0-1~ asf.
Panel ~2 - shows a bright well leveled, ductile deposit free
from low current density defects and a uniform
bright range~
Panel #3 - shows a ductile deposit with good brightness and
leveling, excellent bright range, freedom fxom
low current density darkness and skip plate.
Panel ~4 - shows a ductile deposit with good brightness and
levelins, good bright range and freedom from
low current density darkness and s~ip plate~
Panel ~5 - shows a ductile deposit with good brightness and
leveling, uniform bright range, and freedom
~; from low current density defects.
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Although this invention has been illustrated by
reference to specific embodiments, modifications thereof which
are clearly within the scope of the invention will be apparent
i. to those skilled in the art.
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