Aqueous,alkaline,cyanide-free bath for the galvanic deposition of zinc and zinc alloy coatings

a technology of zinc alloy coating and alkali bath, applied in the field of alkali galvanic bath, can solve the problems excessive thickness of zinc layers in areas of high current density, and uneven layer thickness distribution of zinc layers obtained according to these documents

Inactive Publication Date: 2010-09-23
ATOTECH DEUT GMBH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, they have the disadvantage that their current efficiency is always 100% across a wide range of current densities.
However, in the case of substrates having a complex geometry, this results in excessively thick zinc layers in areas of high current density and to thin zinc layers in areas of low current density.
DE 25 25 264 and U.S. Pat. No. 3,884,774 describe such electrolytes; however, the zinc layers obtained according to these documents do not show a uniform layer thickness distribution.
A disadvantage of this method is the high concentration of reducing sugars which results in increased COD and TOC contents in the effluent water.

Method used

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  • Aqueous,alkaline,cyanide-free bath for the galvanic deposition of zinc and zinc alloy coatings
  • Aqueous,alkaline,cyanide-free bath for the galvanic deposition of zinc and zinc alloy coatings
  • Aqueous,alkaline,cyanide-free bath for the galvanic deposition of zinc and zinc alloy coatings

Examples

Experimental program
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Effect test

preparation example 1

Synthesis of 1-(4′-methoxy-benzyl)-3-carbamoyl-pyridinium-chloride

[0066]In a 100 ml round-bottom flask with reflux condenser, 60 ml of water, 9.2 g of nicotinic acid amide (98%) (0.0738 mol), 11.68 g of 4-methoxybenzylchloride (99%) (0.07378 mol) are heated under reflux for 24 hours. After completion of the reaction, the water is removed in vacuo and the residue is taken up in 200 ml of ethanol and heated under reflux for another hour. The reaction mixture is then cooled to 4° C. and the white solid obtained is removed by filtration and dried in vacuo. This yielded 16.92 g of a white solid (82.26% of the theoretical yield).

preparation example 2

Synthesis of 1-(4′-chloro-benzyl)-3-carbamoyl-pyridinium-chloride

[0067]In a 100 ml round-bottom flask with reflux condenser, 60 ml of ethanol, 10 g of nicotinic acid amide (98%) (0.0802 mol), 13.05 g of 4-chloro-benzylchloride (99%) (0.0802 mol) are heated under reflux for 24 hours. After completion of the reaction, the solid residue is heated in an ethanol / methanol mixture for another 15 minutes and then cooled to 4° C. The solid obtained is removed by filtration and dried in vacuo. This yielded 18.82 g of a white solid (82.87% of the theoretical yield).

preparation example 3

Synthesis of 1,1′-(xylenyl)-3,3′-bis-carbamoyl-bis-pyridinium-dichloride

[0068]In a 100 ml round-bottom flask with reflux condenser, 60 ml of ethanol, 10 g of nicotinic acid amide (98%) (0.0802 mol), 7.16 g of α,α′-dichloro-p-xylene (98%) (0.0401 mol) are heated under reflux for 24 hours. After completion of the reaction, the solid residue is heated in 200 ml of an ethanol / methanol mixture for another 15 minutes and then cooled to 4° C. The resulting solid is removed by filtration and dried in vacuo. This yielded 12.29 g of a white solid (73.13% of the theoretical yield).

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Abstract

The invention relates to an aqueous, alkaline cyanide-free electrolyte bath for de-positing zinc and zinc alloy coatings on substrate surfaces comprising (a) a source for zinc ions and optionally a source for further metal ions, (b) hydroxide ions, (c) a polymer of general formula I which is soluble in the bath and (d) at least one pyridinium compound of general formula II or III. The electrolyte bath is suitable for the galvanic deposition of bright and even zinc and zinc alloy coatings.

Description

FIELD OF THE INVENTION[0001]The present invention relates to an aqueous, alkaline galvanic bath without addition of cyanide ions as complexing agents for the deposition of zinc and zinc alloy coatings, which bath contains as additives bis-(N,N-diaminoalkyl)urea-α,ω-dihaloalkyl copolymers or oligomers and 3-carbamoyl pyridinium compounds quaternized in the 1-position. Furthermore, the invention relates to a process for the deposition of bright and even zinc and zinc alloy coatings in which the bath is used.BACKGROUND OF THE INVENTION[0002]The zinc deposition from cyanide-containing alkaline solution has had a significant market share for many years. However, increasingly stringent statutory requirements regarding the disposal of used zinc and zinc alloy electrolyte baths and the consequent strict control regarding waste water have resulted in increased interest in cyanide-free zinc and zinc alloy electrolytes.[0003]Such metal coatings are used for improving corrosion properties and f...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): C25D3/56C25D3/22
CPCC07D213/82C25D3/565C25D3/22
Inventor BRUNNER, HEIKOKOHLMANN, LARSHABIG, ELLENTHOM, KONSTANTINVOGEL, ROLAND
Owner ATOTECH DEUT GMBH
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