US1818179A - Electroplating - Google Patents

Description

a bath.

Patented Aug. 11, 1931 UNITED STATES PATENT OFFICE LEON It. WESTBROOK, 0F CLEVELAND HEIGHTS, OHIO, ASSIGNOR, BY MESNE ASSIGN- MENTS, TO THE GRASSELLI CHEMICAL COMPANY, OF CLEVELAND, OHIO, A COR- POBATION or DELAWARE ELECTROPLATING No Drawing.

baths, of a brightening agent and an organic addition agent.

Practically all addition agents which so far have been found to be beneficial in their action are of a more or less colloidal organic nature and of ill defined and possible varying composition so that it is sometimes difficult to determine from a chemical analysis if a given material will produce constant and reproducible results in an electroplating I have now found that certain so-called dyestuff intermediates which are commercially available in constant and analytically determinable purity are particularly suited as addition agents to electroplating baths.

They are naphthalene compounds which couple with dia-zo compounds and are of an acidic nature, and my preferred addition agents are chemically distinguished by being compounds in which the naphthalene nucleus is substituted by an acidic radical such as the sulfo or carboxylic group and by an amino or hydroxy group or both the latter. It is, of course, necessary that such compounds be water soluble, or soluble in the cadmium-cyanide bath.

My novel cadmium plating baths are produced by dissolving in water a cadmium compound, a cyanide, other electrolytes required to promote the electrodeposition of cadmium, and a small amount of a naphthalene compound containing an acidic group and being capable of coupling with adiazocom- 4 pound. Amongst the other electrolytes re- Application filed February 23, 1928. I Serial No. 256,493.

quired to promote the deposition of. commercially valuable chromium plates, I refer particularly to the so-called brightening agents by which I mean the nickel or copper salts as disclosed in my Patent No. 1,681,509, granted August 21, 1928.

Such a plating bath 'is then used in the conventional manner at the usual temperatures and current densities. The plates obtained are, however, superior in brightness and adhesiveness to those obtained from a similar bath in which theaddition agent has been omitted.

A typical representative of such a novel bath is obtained by dissolving in water, to 1 liter, the following:

-Grams NaCN 120 0& 011), 4s Na SO n soim o 1 10 to 15 grams of one of my novel addition agents or a mixture of such agents is then. dissolved in this bath and, using a cadmium anode and the article to be plated as the cathode, the current is passed through the bath at the usual temperatures and current densities.

. Typical representatives of the class of naphthalene compounds which I found to ,be most useful as addition agents are reprefonic acid).

Naphthionic acid (l--naphthylaminesulfonic acid).

G salt (sodium-beta-naphthol-G-8-disulfonate). It is well known that these compounds will easily couple in aqueous solution with aromatic diazo compounds.

Amon st these I found the naphthylamine monosul onic acids, such as the F, Cleves,

and Laurents acids, to have the most bene- 'ficial efi'ect. I

It is immaterial whether the free acids or their water soluble salts are dissolved in the cadmium cyanide bath, and both can, for purposes of this invention, be considered entirely equivalent.

I claim:

1. An electroplating bath comprising an aqueous solution containing a cadmium comu" pound, a cyanide, a brightening agent, and

an acidic naphthalene compound capable of coupling with a diazo compound.

2. An electroplating bath comprising an aqueous solution containing a cadmium com- ;5 pound, a cyanide, a brightening agent, and

a naphthalene sulfonic acid compound capable of coupling with a diazo compound.

3. An electroplating bath comprising an aqueous solution containing a cadmium compound, sodium cyanide, a brightening agent,

and anaphthylamine monosulfonic acid compound.

4. An addition agent for cadmium cyanide electroplating baths comprising an acidic '85 naphthalene compound capable of coupling with a diazo compound.

5. An addition agent for cadmium cyanide electroplating baths comprising a naphthalene sulfonic acid compound capable of coupling with a diazo compound.

6. An addition agent for cadmium cyanide electroplating baths comprising a na hthylamine sulfonic acid compound.

An electroplating bath comprising an aqueous solution containing a cadmium 'compound, a cyanide, and an acidic naphthalene compound capable of coupling with a diazo compound.

8. The process of producing bright adherent cadmium plates which comprises electrodepositing cadmium from an aqueous solution containing a cadmium compound, a

cyanide, and an acidic naphthalene compound capable of coupling with a diazo compound.

9. The process of producing bright adherent'cadmium plates which comprises electrodepositing cadmium from an aqueous solution containing a cadmium compound, a cyanide, a brightening agent, and an acidic naphthalene compound capable of coupling with a diazo compound.

.10. The process of producing'bright ads herent cadmium plates which comprises electrodepositing cadmium from an aqueous ture.

LEON R. WESTBROOK.