CS241665B1 - Lesculous additive for electrolytic deposition of nickel coatings up to 50 μΐη - Google Patents

Abstract

A gloss-forming additive for the electrolytic deposition of nickel coatings from electroplating baths based on sulphate, chloride or bromide of nickel and boric acid in various proportions, based on a suitable combination of 4 basic groups of organic compounds, ensuring with its catalytic, synergistic and retarding properties a significant reduction in the kinetics of their decomposition, a reduction in their sorption capabilities and at the same time a positive effect on the sorption properties of decomposition products, which enables continuous operation of the electroplating bath with continuous filtration and periodic replenishment of the bath with the gloss-forming additive. This simultaneously increases the stability of electroplating baths, high levelling ability, high gloss of deposited coatings, low porosity and high ductility as well as good adhesion of other coatings. In nickel plating baths, the gloss-forming additive is maintained at a concentration of 20 to 30 ml/ /1000 ml of bath under working conditions - temperature 55 to 70 °C and pH 3.5 to 4.5.

Description

with thicknesses up to 50 μΐη

WITH

Gloss-forming additive for the electrolytic deposition of nickel coatings from galvanic baths based on nickel sulphate, chloride or bromide in various proportions, based on a suitable combination of 4 basic groups of organic compounds ensuring their catalytic, synergistic and retarding properties sorption properties and at the same time it also positively influences the sorption properties of decomposition products, which enables continuous operation of the galvanic bath during continuous filtration and periodic replenishment of the bath with a brightening additive.

This simultaneously results in an increase in the stability of the galvanic baths, high leveling ability, high gloss of the deposited coatings, low porosity and high ductility and good adhesion of other coatings.

In the nickel plating bath, the brightening agent is maintained at a concentration of 20 to 30 ml / 1000 ml bath under operating conditions of 55-70 ° C and a pH of 3.5 to 4.5.

241865

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 certain metals (Zn, Cd, Pb, etc.) and a number of organic compounds such as aldehydes, ketones, acids, amines, pyrazole, imidol, quinoline or their derivatives, azo compounds, etc. plating under working conditions of the nickel-plating bath, ie pH 3.5 to 4.5 and temperatures of 55 to 70 ° C, disintegrates rapidly into decomposition products having a negative effect on the operation of the bath and therefore cannot be used alone. The gloss-forming effect of the substances themselves is little or no. It is noticeable only in their certain combinations, in which the stability and the decomposition rate are considerably slowed down. The decomposition products formed in the galvanic bath accumulate, leading to a decrease in the quality of the coatings and manifesting itself in a reduction in the bath's buffering ability, loss of gloss, increased porosity of the coatings, brittleness, reduced adhesion of other coatings due to surface passivation. By reducing the quality of coatings we 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 most commonly used for decomposition of the reaction products, followed by absorption of the decomposition products on activated carbon, resulting in considerable economic losses (loss of part of the electrolyte, decomposition of virtually all of the brighteners and expense of oxidants). The reaction products are not perfect 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, 0.5 to 5 wt. % salts of aliphatic esters of sulfosuccinic acid, 0.05 to 5 wt. % unsaturated alcohols and derivatives thereof optionally ethoxylated to one or more stages, 75 to 88 wt. water and dosed into the nickel-plating bath 0.5 to 5 percent by volume.

A suitable combination of the above mentioned substances and their mutual proportions 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 brightener and at the same time positively influences the sorption properties of decomposition products. replenishment of the bath with a gloss-forming additive and thus 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 are examples of brighteners for the galvanic deposition of shiny nickel coatings.

Example 1

115 g of benzenesulfoimide, 95 g of sodium allylsulfonamide, 2.5 g of double isodecylsulfosuccinate and 6.5 g of diethoxylated 2-butyne-1,4-diol are mixed with 880 g of water at room temperature in a stirrer to obtain 1000 ml of a brightening agent suitable for the deposition of shiny nickel coatings up to 50 μπι.

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 23 ml / l.

Plating of the test samples was performed at a current density of 5 A / dm ² , voltage

4.5 V and 60 ° C for 35 minutes. The nickel bath had a pH of 4.1. The deposited coatings had an average thickness of 32 μΐη and these properties - equalization 56 ° / o, elongation 5%.

Example 1 a d 2

170 g of benzene disulfonic acid, 45 g of sodium vinyl sulfonate, 2 g of sodium dioalkylsulfosuccinate and 2.5 g of monoethoxylated propargyl alcohol are mixed with 930 g of water at room temperature in a mixer to obtain 1000 ml of a brightener suitable for shining nickel coatings up to 50 / tm. This additive is metered into the electroplating bath as in Example 1 in an amount of 20 ml / l.

Plating of the test specimens was performed under the conditions as in Example 1. The deposited coatings had an average thickness of 33 μΐη and these properties - leveling 59%, ductility 5%.

Claims (1)

SUBJECT Gloss-forming additive for electrolytic deposition of shiny nickel coatings up to 50 µm thick from galvanic baths based on nickel sulphate, nickel chloride or bromide and boric acid in various proportions of pH 3,5 to 5 at temperatures of 50 to 80 ° C, voltage 3, 8 to 5.3 V and current densities of 2 to 10 A / dm ² , characterized in that the brightener comprises 10 to 30 wt. % of the aromatic compounds with an unsaturated bond between the carbons adjacent to the sulfone group, will be invented 5 to 50 wt. % salts of unsaturated aliphatic sulfonates, 0.5 to 5 wt. % salts of aliphatic sulfofantaric acid esters, 0.05 to 5 wt. % of unsaturated alcohols and their derivatives, optionally ethoxylated to one or more stages, 75 to 88 wt. % water and dosed into the nickel plating bath in an amount of 0.5 to 5 volume%.