CS242583B1 - Additive for galvanic zinc bath with low cyanide and zinc content - Google Patents

Abstract

The invention concerns the formulation of an additive to a galvanic bath for the deposition of semi-gloss zinc coatings on stationary hanging goods, namely a bath with a low content of cyanides and zinc, enabling the deposition of high-quality coatings. The additive is formed by a solution containing from 2 to 23 wt. % of alkali silicates, from 0.2 to 16 wt. % of polyetheralkylene alcohol, e.g. polyethylene glycol, gloss-forming additives, e.g. from 0.02 to 8 wt. % of disodium salt of ethylenediaminetetraacetic acid, from 0.5 to 15 wt. % of ethyl vanillin, from 0.1 to 6 wt. % of gelatin, from 0.001 to 0.2 wt. % of heterocyclic diazone, e.g. pyrimidine, from 0.002 to 0.7 wt. %, calculated as metallic manganese, simple or complex manganese compound and up to 100 wt.% solvents, for example ethanol and water.

Description

The invention relates to an additive for a galvanizing bath and a low cyanide content and zinc for the deposition of semi-gloss zinc coatings upon the movement of the plated goods * or the mixing box in the plating bath.

Galvanic zinc baths with a high content of cyanides and zinc are well-known and well-used. With the same content. cyanides, these baths are ecologically unsuitable # disposal of their wastewater is difficult both toohnically and economically. It will reduce the ecological nobozpočnoati of the zinc plating process under cyanide congestion as well as the savings of zinc plating operation by developing zinc baths with low zinc and cyanide content. Known additives for this type of bath are both economically and economically demanding and based on raw materials not produced in the domestic industry. This fact has hindered the use of more environmentally friendly galvanic baths with low cyanide and zinc abrasions. The newly developed home additives of this type of zinc baths, formulated on the basis of domestic raw materials *, allow zinc zinc baths alo ponzo to move nobo plated goods when mixing the bath. The conditions of the movement of goods in non-plating can be met by the vast majority of galvanovon * where the most suitable prerequisite for expanding the process. Highly developed household ingredients for zinc baths will then not ensure a satisfactory flow efficiency of the bath and achieve the desired plating parameters.

Insufficient deficiencies in the conditions of static zinc plating from the galvanizing bath and low cyanide and zinc content eliminate the additive according to the invention * which is based on the fact that the additive is formed by alkali metal silicas *

and

242 583, for example, sodium siliconitone, in amounts of 3 and 33 wt. ft, pelyetharalkylenealkehel, for example pelyethylene glycol, in amounts of ad 0.3 and 16 knots. % by weight of a curing agent, for example, 2-ol and other ethylenediaminetetra-cyanolines in an amount of 0.03 to 8 wt. % _t otylvanilinoa in anodat from 0.5 to 15 tactile · 1, with gelatin in amounts of ad 0.1 and 6 tactile. %, hotorecyclic diazenoma, for example pyriaidinam, in an amount of ad 0.001 da 0.3 tactile. % and a single leg with a complex manganese alautine, for example, a manganese manganese on its palyalkyland sanguine-manganese complex in an amount of 0.003 da 0.7 tactile% at the bulkhead of non-volatile manganese, drawn on the volatile weight of the additive. The rest da 100 touches. % are solvents such as atanal and defect.

Production of the additive is simple, from domestic raw materials, does not require and lies td synthesis. The bath and the additive of the invention allow for zinc suspension baking without moving the goods and / or mixing the bath. It works in the rexaozi of current densities up to 0.5 da d, 0 a / dm, the coatings are covered with avat brown film and semi-glossy. Temperature ad 80 da <0 ° C.

The invention will be explained in more detail by way of example of a specific embodiment thereof.

Example 1

In the zinc bath containing 10.3 g / l of zinc, 13 g / l of sodium cyanide and 60 g / l of sodium hydroxide, the additive of the invention was added in an amount such that the bath contained 3.3 g / l of pelyethylene glycol in the bath. 0.3 g / l, two-seated salts of ethylenediaminetetraeetic acid 0.03 g / l, otylvanillin 5.3 g / l, pyrimidine 0.0d g / l, gelatin 2.0 g / l and manganese ion 0.1 g / l . The bath formed in the labaratory conditions the semi-gloss coatings on the goods plated with gold when the goods were hung on the stationary cathode rod and showed good leaching efficiency and hiding power.

Example 3

In a galvanic bath containing 13 g / l zinc, 1 g / l sodium cyanide and 80 g / l sodium hydroxide, the additive of the present invention was given in a flowable amount to provide a silicate content of 8.8 g / ml. 1, pelyethylene glycol 4 g / l, disodium salt of ethylenediamiaotetraeetic acid 0.4 g / l, otylvaailin 3.5 g / l, pyrimidine 0.02 g / l, gelatin 0.05 g / l, manganese salt 0.005 g / l . In the laboratory tests under the conditions of static metallization of samples, semi-glossy zinc coatings were formed on the goods, covered with a weak yellowish coating, and the X disappeared after clarification with nitric acid. Good coating quality was obtained at current densities ranging from 0.5 to 4.0 A / dm ** and temperatures from 20 to 40 ° C.

Example 3

Into the galvanizing bath containing 11.1 g / l of zinc, g / l of sodium cyanide and 85 g / l of sodium hydroxide, the additive according to the invention was applied so that the bath had a silicate content of 4 g / l, polyathylene glycol 1.4 g / l. 1, disodium selylaadiaminetetraeetic acid 0.2 g / l, otylvanillin 0.8 g / l, phyrimidine 0.005 g / l, gelatin 0.8 g / l and manganese ion 0.02 g / l. In the laboratory tests the bath showed good excretion efficiency, hiding power and quality of the deposited coatings.

In-service tests have shown that the bath and additive of the present invention are suitable for the galvanizing of goods under static conditions, i.e. without moving the goods, and that they give semi-gloss coatings of unimaginable quality.

Claims (1)

SUBJECT OF THE INVENTION 242 583 Low-cyanide-zinc galvanizing bath additive characterized in that it consists of alkali metal silicates, for example sodium silicate in an amount of from 2 to 23% by weight. % polyetheralkylene alcohol, for example pelyethylene glycol, in an amount of from 0.2 to 16 wt. % of a brightening agent, for example, disodium ethyleneaminototraootic acid in an amount of 0.02 to 8 wt. from 0.5 to 15 wt. %, a gelatin in an amount of 0.1 to 6 wt.%, a hotoroeylic diazone, e.g. % and a simple manganese complexed manganese compound, for example, manganese sulphate or pelyalkylana manganese complex in an amount of from 0.002 to 0.7% by weight based on the total weight of the additive; the remainder to 100 wt. they are solvents such as ethanol and water.