Electrolysis: processes – compositions used therein – and methods – Electrolytic coating – Depositing predominantly single metal coating
Patent
1994-07-25
1995-08-29
Niebling, John
Electrolysis: processes, compositions used therein, and methods
Electrolytic coating
Depositing predominantly single metal coating
205279, C25D 316, C25D 318
Patent
active
054457270
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to an improved process for producing nickelized shaped articles by electrodeposition of nickel from aqueous acidic baths containing as essential constituents one or more nickel salts, one or more inorganic acids and at least two brighteners, and to a brightener mixture usable for this purpose.
It is known that acidic nickel electrolytes must contain small amounts of organic substances if the electronickelization is to produce a bright, ductile and surface-planar deposition of the metal. Such brighteners, which in general are divided into primary and secondary brighteners, are customarily used in the form of combinations comprising a plurality of these agents in order to enhance the effect.
Praktische Galvanotechnik, Eugen G. Lenze Verlag, Saulgau, 4th edition 1984, pages 268 to 271 (1) describes customary brighteners for nickel electrolytes. Although the compounds are classified as primary or secondary brighteners or planarizers, it is admitted at the same time that clear-cut classification is not always possible. The brightening compounds mentioned are: further hetero atoms such as
DE-B-1 191 652 (2) describes single- or multiring heterocyclic nitrogen bases of the aromatic type in quaternized form such as pyridinium salts, eg. 2-pyridinium-1-sulfatoethane, as planarizers, ie. brightners, for acidic nickel-plating baths. These agents are used together with customary basic brighteners such as benzene-m-disulfonic acid, diaryldisulfimides or sulfonamides.
U.S. Pat. No. 2,647,866 (3) describes mixtures of N-substituted pyridinium compounds, eg. N-allylpyridinium or N-methallylpyridinium halides, with certain sulfur-containing compounds, eg. allylsulfonic acid, as highly effective brighteners in the electrodeposition of nickel. A use concentration of from 4 to 12 g/l is recommended for allylsulfonic acid.
However, the prior art agents generally need to be used in relatively high concentrations in the nickel electrolyte baths used; what is more, the brightness and planarization achievable with these agents are still in need of improvement.
It is an object of the present invention to remedy the aforementioned defects of the prior art.
We have found that this object is achieved by a process for producing nickelized shaped articles by electrodeposition of nickel from aqueous acidic baths containing as essential constituents one or more nickel salts, one or more inorganic acids and at least two brighteners, which comprises using as brighteners a mixture of
A) from 2 to 98% by weight of one or more cyclic N-allylammonium or N-vinylammonium compounds of the general formula I ##STR2## where the nitrogen atom is part of a pyridine, quinoline or isoquinoline ring system which may additionally carry one or two C.sub.1 - to C.sub.4 -alkyl substituents or halogen atoms, -alkyl, solubility in water, and
B) from 98 to 2% by weight of one or more acetylenically unsaturated compounds of the general formula II to C.sub.4 -alkyl substituted by hydroxyl, sulfo, amino, C.sub.1 - to C.sub.4 -alkylamino or di(C.sub.1 - to C.sub.4 -alkyl)-amino, although hydroxyl groups may have been reacted with from 1 to 10 mol of a C.sub.2 - to C.sub.4 -alkylene oxide or a mixture of such alkylene oxides and one of the radicals R.sup.4 and R.sup.5 may also be hydrogen or C.sub.1 -to C.sub.4 -alkyl.
Suitable C.sub.1 - to C.sub.4 -alkyl radicals are in general n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tertbutyl and in particular methyl and ethyl.
Examples of alkyl- or halogen-substituted heterocycli ring systems for I are:
The term halogen atom herein encompasses fluorine, iodine and in particular bromine and chlorine.
Preference is given to unsubstituted pyridinium.
R.sup.1, R.sup.3 and R.sup.4 are preferably each hydrogen.
The variable m is preferably 1.
Suitable n-valent anions X are the customary, normally water-solubilizing inorganic or organic anions, in particular chloride, bromide, fluoride, sulfate, hydrogensulfate, methanesulfonate, trifluoromethanesulfonate, 2-hydroxyethanesulfonate, p-toluenesulfon
REFERENCES:
patent: 3758389 (1973-09-01), Maekawa
patent: 3862019 (1975-01-01), Rosenberg et al.
"Praktische Galvanotechnik", Eugen G. Lenze Verlag, Saulgau, 4th ed. (1984), pp. 268-271 No Month.
Burkhart Bernd
Dung Bernhard
Glaser Klaus
Oftring Alfred
Schwendemann Volker
BASF - Aktiengesellschaft
Niebling John
Wong Edna
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