DE2050796A1 - Brightening agent for obtaining glossy electrolytic cadmium coatings - Google Patents

Description

Brightening agents for achieving glossy electrolytic

Cadmium coatings ,

The invention relates to a brightening agent which enables glossy electrolytic cadmium coatings to be obtained starting from an aqueous solution of a cadmium salt, e.g. starting from a solution of cadmium sulfate and sulfuric acid or one Ammonium salt.

The Kadmiura electrolytic coatings are becoming common obtained from cyanide baths; However, this method has the disadvantage that the wastewater is a Problem. When using acidic baths, the deposits obtained are dull and that too Penetration of the baths is insufficient. If, after all, you don't get cyanide baths, but complex-

10 9 8 19/1737 Dr Ha / Mk

BATH ORIGINAL

If baths containing forming substances are used, the problem of wastewater also arises.

The invention aims to avoid these disadvantages by using an electrolyte without cyanide compounds or complexing compounds used and yet achieved a glossy Kadmiura coating, starting out of a wide current density range, which gives the bath an eye-catching level of penetration.

The brightener according to the invention comprises a basic compound consisting of a nitrogen derivative of aldehydes or ketones. In particular, they give by the action of thiosemicarbazide or dithiocarbamic acid derivatives obtained on phenol aldehydes or their derivatives; preferred becomes the compound obtained by reacting the thiosemicarbazide with dioxy-1,2-benzaldehyde-4 used.

To achieve maximum gloss and penetration, they are used together according to the invention derivatives complementary to the above basic compound, namely: the naphthalenesulfonic acids or their salts, in particular the naphthalene sulfonate-2 of sodium; the sulfonated derivatives of aikylbenzimidazoie the common Pormex:

R - er / ° 6 ^H 3 " ^S0 3 ^Ka

as well as alkyl, aryl derivatives or the quaternized ones

109819/1737 _{bi / mmäi}

bad original

Derivatives; the condensation products of naphthalenesulphonic acids and formaldehyde, e.g. sodium dinaphthalenemethylene disulphonate or its alkyl derivative; the imisazoline derivatives, especially those of amphoteric character.

In certain cases it is advisable to have a sufficient Dispersion of the brightener and those combined with it Substances the use of complementary anionic or non-ionic wetting agents, especially those that formed by reaction of ethylene oxide groups with alcohols or fatty acids or alkylphenols. Below examples of compositions are given:

example 1

Cadmium sulphate 60 g / l

Sulfuric acid 60 g / l

by reaction of thiosemicarbazide with methanedioxi-1,2-benzaldehyde-4 product obtained 0.5 g / l Iiatrium naphthalenesulfonate-266 g / l

nonionic wetting agents of the type i \ ^T onylphenol with 9 molecules of ethylene oxide, 4 g / l

3eis-Qiel 2

Cadmium sulfate 45 g / l

Sulfuric acid 50 g / l

by reaction of thiosemicarbazide with Hethandioxi-1,2-benzaldehyde-4 product obtained 0.5g / l

sulfonated derivative of the under 1 9 1 9/1 737

BATH ORIGINAL

Benzimidazoles known under the name Albatex PO. 4 g / l

non-ionic wetting agent of the fatty acid type with C ₁₈ with 30

Molecules of ethylene oxide 2 g / l

Example 3

Cadmium sulfate 50 g / l

Sulfuric acid 30 g / l

by reaction of thiosemicarbazide with methane-dioxi-1,2-benzaldehyde-4 product obtained 0.5g / l

Sodium dinaphthalene methylene disulfonate 4 g / l

non-ionic wetting agent of the dodecylphenol type with 12 molecules of ethylene oxide 3 g / l

Example 4

Cadmium sulphate 60 g / l

Sulfuric acid SO g / l

by reaction of thiosemicarbazide with methane-dioxi-1,2-benzaldehyde-4 product obtained 0.6g / l

1098 19/1737

BATH ORIGINAL

Matrium-naphthalenesulfona1i - 2 1.5 g / l Albatex PO 3 g / l

non-ionic wetting agent from
Q} yp Nonyiphenol with 9 molecules
Ethylene oxide 2.5 g / l

. Example 5

Cadmium fluorate 80 g / l

Ammonium fluorate 50 g / l

by reaction of Ihiosemicarbazid with methane-dioxi-1, 2-benzaldenyd-4 product obtained 0.2 g / l

amphoteric derivative of coconut cycloimidazoline 10 g / l

Sodium dinaphthalene methylene disulfonate 2 g / l

The baths consisting of the electrolytes of the preceding examples give a very good gloss inside a current density range of 0.5 to 5 A / dm

The favorable operating temperature is 20 + 5 ⁰ C.

109819/1737 8A0 ORIGINAL

Claims (2)

β - Claims Brightening agent for producing glossy electrolytic cadmium coatings based on an aqueous solution of a cadmium salt, e.g. a solution of cadmium sulfate and sulfuric acid or an ammonium salt consisting of a nitrogen-containing derivative of Aldehydes or ketones, e.g. that produced by the reaction of thiosemicarbazide with methane-dioxi-1,2-benzaldehyde-4 obtained product, with at least one complementary compound from the following group: a naphthalene sulf onic acid or one of its salts, a sulfonated benzimidazole derivative, an amphoteric imidazoline or Benzimidazoline derivative, a condensation product of naphthalenesulfonic acids and formaldehyde. 2. Gloss agent according to claim 1, characterized in that it is still an anionic or non-ionic Contains wetting agents. 109819/1737