CS241664B1 - Lustre agent for electrolytic deposition of lustre nickel coatings with thickness not more then 25 micrometers - Google Patents

Abstract

Fluorescent additive for electrolytic deposition of nickel coatings of galvanic sulphate, chloride or bromide based baths of nickel and boric acid in different ratios based on a suitable combination 5 basic groups of organic compounds providing their catalytic, synergistic and retarding properties are essential reduce the cnetics of their decay, reduce their sorption abilities and at the same time favorably it also affects the sorption properties of decomposition products, allowing for continuous filtration and periodic refilling of the bath both the colorant and the continuous ingredient galvanic bath. This simultaneously increases the stability galvanic bath, high leveling ability, high gloss excreted coatings, low porosity and high ductility i good adhesion of other coatings. It is maintained in the nickel-plating baths by the brightening additive at 20 to 30 ml / 1000 ml bath under working conditions - a temperature of 55 to 70 ° C and a pH of 3.5 to 4.5.

Description

The present invention relates to brighteners for the electrolytic deposition of shiny nickel coatings from nickel sulphate, nickel sulphate, chloride or bromide and boric acid electroplating baths in various proportions. . -

To date, a wide variety of organic or inorganic additives have been designed and used for the galvanic deposition of shiny nickel coatings, which are usually divided into two classes.

Substances in Class 1 contain a sulfur atom in their molecule - these are most often different types of organic sulfo acids and their esters, sulfonamides, sulfoimides, sulfones, etc.

Class 2 includes salts of some metals (Zn, Cd, Pb, etc.) and a number of organic compounds such as aldehydes, ketones, acids, amines, pyrazole, imidazole, quinoline or their derivatives, azo compounds, etc. Most of these organic substances themselves during plating under the working conditions of the nickel-plating bath, ie pH 3.5 to 4.5 and temperatures of 55 to 70 ° C, it decomposes rapidly into decomposition products with a negative influence on the bath start and cannot be used by themselves. The gloss-forming effect of the substances themselves is little or no. It is markedly manifested in their certain combinations, in which stability is simultaneously positively influenced and the rate of decomposition considerably slowed down. Decomposition products formed in the galvanic bath accumulate in the decomposition, resulting in a decrease in the quality of the coatings and manifesting itself in a decrease in the bath's buffering capacity, loss of gloss, increased porosity of the coatings, brittleness; reduced adhesion of other coatings due to passivation of the surface layer. Decreasing the quality of coatings can reach the limit of unusability.

For these reasons, it is necessary to remove the reaction products from the galvanic bath. Strong oxidizing agents (hydrogen peroxide or potassium permanganate) are used most frequently for decomposition of the reaction products, followed by absorption of decomposition products on activated carbon. This results in considerable economic losses (loss of part of the electrolyte, the decomposition of virtually all of the brightening agents and the cost of the oxidant). The removal of the reaction products is incomplete and must be repeated periodically.

The above-mentioned drawbacks are overcome by the brightening agent according to the invention, which consists of 10 to 30% by weight. % of aromatic compounds with an unsaturated bond between the carbons adjacent to the sulfone group, 5 to 50 wt. % of unsaturated aliphatic sulfonates, 0.05 to 5 wt. % salts of aliphatic esters of sulfosuccinic acid, 0.05 to 5 wt. % of unsaturated alcohols and? - derivatives thereof optionally ethoxylated to one or more degrees, from 0.0005 to 1% w / w; % of substituted aminoacetylenes or their addition products with sulfuric or hydrochloric acid, 75 to 88 wt. water and is added to the nickel-plating bath in an amount of 0.5 to 5% by volume.

A suitable combination of the above mentioned substances and their mutual ratios by their catalytic, synergistic and retarding properties ensures a substantial reduction of their decay kinetics, decreases the sorption ability of the basic components of the brightening agent on activated carbon, while favorably affecting the sorption properties of decomposition products. Coal and periodic replenishment of the bath with a gloss-forming additive and thus also the continuous operation of the bath, which is positively manifested also by increasing the stability of galvanic baths, high leveling ability and gloss, low porosity and high ductility.

The following is an example of a brightening agent for the galvanic deposition of shiny nickel coatings.

He did

115 g of benzenesulfonimide, 95 g of sodium allylsulfonate, 2.5 g of sodium diamylsulfosuccinate, 2.2 g of diethoxylated 2-butyne-1,4-diol and 1.5 g of dimethylaminopentine are mixed with 810 g of water at room temperature in a stirrer to obtain with 1000 ml brighteners suitable for the deposition of shiny nickel coatings up to · 25 micrometers thick. This additive is dispensed into a galvanic bath containing, per 1000 ml, 300 g of nickel sulfate, 60 g of nickel chloride and 40 g of boric acid, in an amount of 25 ml / l.

Plating of the test samples was performed at a current density of 5 A / dm ² , a voltage of 4.5 V and a temperature of 60 ° C for 20 minutes, the nickel bath having a pH of 4.1. Excluded coatings had an average thickness of 19 μϊΆ and properties - leveling 66%, ductility 5%.

Claims (1)

SUBJECT Gloss-forming additive for electrolytic deposition of shiny nickel coatings up to 25 μΐη thick from galvanic baths based on nickel sulphate, nickel chloride or bromide and boric acid in various proportions at temperatures of 50 to 80 ° C, voltages of 3.8 to 5.3 V and current densities of 2 to 10 A / dm ² , characterized in that it consists of 10 to 30 wt. % of aromatic compounds with an unsaturated bond between the carbons adjacent to the sulfone group, 5 to 50 wt. % salts of unsaturated aliphatic sulphates, OF THE INVENTION 0.05 to 5 wt. % salts of aliphatic esters of sulphosuccinic acid, 0.05 to 5 wt. % of unsaturated alcohols and their derivatives, optionally etlioxylated to one or more degrees, 0.0005 to 1 wt. % of substituted aminoacetylenes or their addition products with sulfuric or hydrochloric acid, 75 to 88 wt. % of water and added to the electroplating nickel bath in an amount of 0.5 to 5 vol.