DE1133957B - Wetting agent for galvanic baths - Google Patents

Description

It is known, electroplating baths for the production of nickel, copper or zinc coatings Add wetting agent. These additives cause the hydrogen to be released during the electroplating process forms on the cathode, is delivered quickly and as completely as possible. For longer Residence time on the cathode material, the hydrogen causes a disruptive pore formation in the galvanic Metal coatings.

The prevention of pore formation is important in electroplating with regard to the desired corrosion resistance the metal supports are of great importance. Another task of the wetting agent lies in the electrophoretic deposition of small contaminant particles on the metal surfaces prevent, as the corrosion resistance through the incorporation of foreign matter in the galvanic deposits also suffers.

More recently, wetting agents have also been used in chrome baths. This ensures that the in Oxygen and hydrogen released from the chrome baths as a result of poor electricity yields do not occur in the form of a mist, but rather form a layer of foam on the chrome bath liquid. This results in considerable losses of relatively expensive chrome bath liquid due to continuous suction the mist prevents, so that in many cases the bath suction can be dispensed with.

Despite the large number of known wetting agents, the selection of useful substances for the Electroplating relatively low. So get in nickel baths alkyl sulfonates, alkyl sulfates and Aralkyl sulfonates or sulfates are preferred for use, while in the field of acidic and cyanidic copper plating of the alkyl polyglycol ethers. As a permanent wetting agent in chrome baths perfluorinated alkyl sulfonates are known.

It has now been found that the acidic, halogen-free alkyl or alkaryl phosphoric acid esters as well Alkyl polyglycol ether phosphoric acid esters or their salts in a wide variety of electroplating baths Advantage to use. In addition to their good wetting agent properties, these compounds have properties compared to the corresponding sulfonates or sulfates the advantage that they are considerable in the baths are more stable. They also have the advantages over the alkyl polyglycol ethers that they have no cloud point and are not salted out even in cyanide hot copper baths. In cyanide baths, the phosphoric acid esters even have gloss-giving properties. In chrome baths The alkyl phosphates in particular have a wetting agent for electroplating baths

Applicant:

Dehydag, Deutsche Hydrierwerke G. m. B. H., Düsseldorf, Henkelstr. 67

Dr. Wennemar Strauss, Düsseldorf-Holthausen,
and Dr. Rudi Heyden, Düsseldorf,
have been named as inventors

excellent resistance, so that they replace the expensive and difficult to manufacture perfluorinated organic sulfonic acids can be used.

Compounds of the claimed type are, for. B. the acidic mono- or diphosphoric acid esters of Octyl, decyl, dodecyl, octadecyl, octadecenyl alcohol or of hexyl-, octyl- or dodecylphenol or their water-soluble salts as well as the Phosphoric acid esters of alkyl polyglycol ethers of the general formula

C _n H ₂ ^ ₁ O (CH ₂ CH ₂ O) _7n CH ₂ CH ₂ OPO ₃ X ₂

in which «= 8 to 20 and m is 0 to 50 and X is hydrogen or an inorganic or organic base.

The wetting agents can be used in acidic, cyanidic or alkaline baths for the production of electroplating Copper, nickel, chrome, zinc, cadmium, tin, brass, bronze, gold and silver coatings are used will. They are preferably added to the baths in amounts of 0.01 to 5 g / l.

example 1

Dissolving 0.01 to 0.2 g / l dodecyl phosphoric acid ester in a cyanidic copper bath containing 105 g / l copper cyanide, 128 g / l sodium cyanide and 30 g / l sodium hydroxide, one obtains in the electroplating of objects made of iron or Steel between 60 and 80 ° C in the current density range of about 1 to 6 Amp./dm ² pore-free copper deposits. These precipitates stand out compared to those without and under

209 627/286

otherwise the same conditions can be achieved by a significant grain refinement.

Example 2

In a bright chrome bath made up of 290 g / l CrO ₃ , 0.02 to 0.1 g / l octyl phosphoric acid ester are dissolved. When chrome-plating bright nickel-plated objects with current densities of 10 to 20 Amp./dm ² at 35 to 40 ° C, a foam layer about 1 to 2 cm thick is formed, which completely prevents the occurrence of chromic acids. The chrome plating is high-gloss.

Example 3

An acidic copper bath is added which, in addition to 200 g / l Cu SO ₄ -5 H ₂ O and 60 g / l H ₂ SO _4, 0.25 g / l NjN-diethyl-dithiocarbamic acid-n-propyl ester-Cu-sulfonic acid sodium and Contains 2 g / l of l-diethylamino-3-chloropropanol-2 as a gloss-imparting agent, with 0.01 to 0.3 g / l of the compound

C ₁₂ H ₂₅ O (CH ₂ CH ₂ O) ₇ CH ₂ CH ₂ OPO ₃ Na ₂ ,

In this bath, when iron or brass objects are electroplated in the current density range from 0.5 to 7.5 Amp./dm ^2, high-gloss copper deposits which are completely pore-free are obtained.

Claims (1)

Claim
Use of acidic, halogen-free alkyl or alkaryl phosphoric acid esters with at least 8 carbon atoms in the molecule, the alkyl radicals of which can optionally be interrupted by oxygen atoms, or their water-soluble salts as wetting agents in electroplating baths. Considered publications:
German interpretative document No. 1023 647.