DE1910466A1 - Acid zinc bright plating bath - Google Patents

Abstract

The plating bath contains zinc salts, brightening and wetting agents and derivatives of polymeric or oligomeric reaction products of equimolar amounts of alkylene polyamines and aliphatic alpha,omega-bifunctional alkylating agents which contain 3-8 carbon atoms in a straight chain and whose nitrogen atoms are substituted by 1-4C aliphatic radicals capable of carrying hydroxyl, carboxyl or sulphonic acid groups. Specifically, the derivatives are those of polymeric or oligomeric reaction products of equimolar amounts of alkylene polyamines and epichlorohydrin. A further addition is thiourea and cadmium salt. The wetting agent is a short-chain branched alkyl sulphate.

Description

Acid galvanic bright zinc bath Most of those used in practice Bright zinc baths still work today in the alkaline range. Among the alkaline In the baths, the cyanidic bright zinc baths play the greatest role. if Even the detoxification of the resulting wastewater is not a technical problem today represents more, it is a cost factor that repeatedly gives rise to criticism on this type of bathroom. There has therefore been no lack of attempts to find the Cyancal Replace bright zinc baths with other bath types.

In addition to cyanide-free alkaline zinc baths, acidic baths were used for this purpose Zinc baths developed in which the wastewater without difficulty and major costs can be eliminated. In addition to this advantage of the easy disposal of sewage However, the acidic zinc baths have a number of disadvantages that they for a make extended technical use unsuitable. So fall with some Bath the precipitates matt and if it succeeds, the precipitates shine to lend, leaves theirs Deep scattering is still very much to be desired remaining and the current density range in which glossy precipitates are obtained, remains very narrow. In addition, the precipitates obtained show many times a strong embrittlement.

Despite all efforts, it did not succeed, all of the disadvantages at the same time to counteract effectively, but there will always be only limited and one-sided improvements achieved, which often enough bring about a gain of another disadvantage. The desire for an acidic bright zinc bath therefore remains open, as before Well shining, non-brittle precipitates over a wide range of current densities delivers with good depth dispersion.

It has now been found that these requirements are largely met leave, if you have an acidic galvanic bright zinc bath with a content of soluble Zinc salts, optionally further conductive salts, in addition to customary brighteners and wetting agents used, the additional derivatives of polymer bwz. oligomeric reaction products equimolar amounts of alkylene polyamines and aliphatic α, w-bifunctional Contains alkylating agents with 3 to 8 carbon atoms in a straight chain, the substituted on the nitrogen atoms by aliphatic radicals with 1-4 carbon atoms which can carry hydroxyl, carboxyl or sulfonic acid groups.

As α, w-bifunctional alkylating agents with 3 to 8 carbon atoms in a straight chain are, for example, 1,3-dichloropropane, 1,4-dichlorobutane, 1,5-dichloropentane, 1,6-dichlorohexane, 1,8-dichloroctane, 1,4-dibromobutene, 1,3-dichlorohydrin, epichlorohydrin and diepoxybutane. The preferred alkylating agent is epichlorohydrin to address.

Derivatives of such reaction products of alkylene polyamines with aliphatic α, # - bifunctional alkylating agents which are suitable for the use according to the invention come into question are, for example, on the nitrogen atoms by ethyl, propyl, Allyl, propargyl, oxyethyl, γ-chloro-ß-oxy-propyl, acetic acid, propionic acid, Succinic acid, propanesulfonic acid, butanesulfonic acid, oxypropanesulfonic acid residues, optionally substituted in the form of corresponding salts.

To make the products one leaves in water and / or organic Solvent equimolar amounts of alkylene polyamine and alkylating agent with heating react with one another and then use the reaction mixture obtained for substitution on the nitrogen atoms with corresponding amounts of halogen compounds such as ethyl, Propyl, allyl, propargyl chloride, chloroacetic acid, chloropropionic acid, chlorosuccinic acid, Chloroxypropanesulfonic acid, glycol chlorohydrin or epoxy compounds such as epichlorohydrin or propane sultone or butane sultone, optionally in the presence of acid scavengers, around.

The alkylene polysmines used for the reaction with aliphatic α, # - bifunctional Alkylating agents primarily low molecular weight polyamines such as ethylenediamine, ProSylenediamine, diethylenetriamine, triethylenetetramine and Tetraethylene pentamine in question. Products obtained in this way containing primarily tertiary nitrogen atoms possibly contain in addition to unreacted secondary nitrogen atoms, require, if they are not in the form of salts, the addition of a corresponding one Amount of free acid to become sufficiently water-soluble.

By further reaction with the halogen and epoxy compounds mentioned or propane sultone or butane sultone, products with quaternary nitrogen atoms, who carry two such substituents create one that is ready by itself have sufficient water solubility.

Those derivatives of alkylenepolyamine reaction products are of particular importance here, for their preparation 1-2 moles of the aforementioned halogen, vpoxy compounds per nitrogen atom or propane or butane sultone were used. Products have an effect the anode N-alkyl substituents carry carboxyl or sulfonic acid groups on the whole the properties of the zinc deposit are particularly favorable.

The application concentration of the derivatives to be used according to the invention of alkylenepolyamine reaction products is between 0.01 and 10 g per liter, preferably 0.05-2 g / l bath liquid. The applicable current densities are in Range of 0.5 - 8 A / dm2 at a bath operating temperature of 10 - 40 ° C, preferably 15-30 ° C. The baths are depending on the composition and the nature of the additive in the pH range from 2 - 5 operated.

The effect of the products used according to the invention is through the simultaneous addition of thiourea to the Baths essential reinforced. The use concentration of thiourea is generally between 0.5 - 3 g / l bath liquid.

A further improvement in the deposited zinc precipitates leaves can be achieved by adding cadmium to the bathroom. The one with some bathroom compositions The yellow tinge of the zinc precipitate that occurs due to the addition of cadmium in a bluish cast. and the precipitate thereby acquires brilliance. Furthermore In some cases, the depth scattering of the bath can be reduced by adding cadmium influence favorably. The amount of cadmium salts added is in the range from 0.02 - 0.5 g / l bath liquid.

Suitable wetting agents for the bright zinc bath according to the invention are primarily short-chain branched alkyl sulfates or sulfonates, such as isohexyl, Isononyl sulfate or isohexyl sulfonate, preference being given to sulfates. Are the polyethyleneimine or polypropyleneimine derivatives used according to the invention only available in very small quantities, longer-chain ones can also be used as wetting agents Alkyl sulfates, such as lauryl sulfate, are used with good success.

The amount of wetting agent used is generally 0.5-1 g / l Bath liquid.

The following examples are intended to provide the subject matter of the present invention explain in more detail without restricting it to it.

Example 1-To make that used in this example 75 g of 1 mol) diethylenetriamine were dissolved in 1 liter of ethanol and heated to 70.degree warmed up. 9'2 g (1 mol) of epichlorohydrin were added dropwise to this solution and the reaction mixture was refluxed for 2 hours. Thereafter was cooled to 700C and the resulting solution used for further processing.

348 g (3 mol) of sodium chloroacetate were added to the warm solution at 700C given and the solution was stirred at 80 ° C. for 1 hour. Then 120 g (3 mol) of sodium hydroxide in aqueous solution were added over the course of 30 minutes. The solution was then concentrated in vacuo and the residue, in addition to the Derivative of the diethylenetriamine-epichlorohydrin reaction product in considerable amounts Containing sodium chloride, dissolved in water to make a 20% solution. 1 cc of this Solution contained ~ 140 mg of the derivative of the diethylenetriamine-epichlorohydrin reaction product in the form of the hydrochloric acid salt and ~ 60mg sodium chloride. This solution was used as an additive used for the following zinc bath: 300 g / l zinc sulfate crystallizes 30 g / l Boric acid 2 g / l thiourea 0.5 g / l cadmium sulfate crystallizes 10 com / l above Solution 0.5 g / l isononyl sulfate. The pH of the bath was 4.5. The bathroom delivered at an operating temperature of 15-30 ° C in the current density range of 1 -6 A / dm² shiny, ductile zinc coatings with good depth scattering.

Example 2 The same procedure was initially used for the following experiment Example 1 a reaction product of equimolar amounts of diethylenetriamine and epichlorohydrin manufactured. 366 g (3 mol) of propane sultone were added dropwise to the 70 ° C. solution added in the course of an hour and then the mixture was stirred at 80 ° C. for 1 hour. The reaction solution was then concentrated in vacuo and the residue to a 20% strength dissolved aqueous solution. 1 ccm of this solution contained-t cm 200 mg of the invention derivatives to be used.

This solution was used as a bath additive: 300 g / l zinc sulfate crystallized 30 g / l boric acid 1 g / l thiourea 0.5 g / l cadmium sulfate crystallizes 5 ccm / i above solution 0.5 g / l isohexyl sulfate. The pH of the bath was 3.0. The bath delivered at an operating temperature of 15-30 0C in the current density range from 1 -8 A / dm2 shiny, ductile zinc precipitates with sufficient depth scattering.

Example 3 First of all, according to Example 1, a reaction product was produced Equimolar amounts of diethylenetriamine and epichlorohydrin are produced. To the 70 ° C warm solution were 218 g (2 mol) Given ethyl bromide, and that The reaction mixture was stirred at 80 ° C. for 1 hour. Subsequently, the same Temperature 436 g (4 mol) of ethyl bromide and 160 g (4 mol) of sodium hydroxide in aqueous Solution was added and the mixture was stirred at 80 ° C. for a further hour. After this Time the solution was concentrated in vacuo and the residue in addition to the quaternary N-ethyl-substituted diethylenetriamine-epichlorohydrin reaction product considerable Containing amounts of sodium bromide, dissolved in water to form a 20% solution. 1 cc of this Solution contained ~ 110 mg of the quaternary derivative and ~ 90 mg of sodium bromide. These Solution was used as an additive in the following zinc bath: 300 g / l zinc sulfate crystallizes 20 g / l boric acid 2 g / l thiourea 10 ccm / l of the above Solution The pH of the bath was 4.5. With the bath were at operating temperature from 15-300C in the current density range of 1 - 6 A / dmt shiny, dulctile zinc deposits obtained with sufficient depth scattering.

Example 4 As a starting material for the in this example according to the invention The product used was again the reaction product prepared according to Example 1 Equimolar amounts of diethylenetriamine, in and EPichlorohydrin used. To the 70 ° C warm Solution were initially 148 g (2 mol) Propargyl chloride and after stirring for one hour at 80 ° C, a further 74 g (1 mol) of propargyl chloride and 40 g (1 mol) Given sodium hydroxide in aqueous solution and the reaction mixture for 1 hour at 80 ° C stirred. The solution was then concentrated in vacuo and the residue in Water added to a 20% solution. 1 cc of this solution contained ~ 170 mg of the N-propargyl derivative, it as hydrochloric acid salt and ~ 30 mg of sodium chloride. The solution was used as an additive in the following zinc bath; 300 g / l zinc sulfate crystallizes 30 g / l boric acid 1 g / l thiourea 0.5 g / l cadmium sulfate crystallizes 6 ccm / l the aforementioned solution The pH of the bath was 4.0. The bathroom delivered at one Operating temperature of 15-30 ° C in the current density range of 1 - 8 A / dm² shiny, ductile zinc precipitation with good depth dispersion.

Example 5 For the preparation of that intended for the following experiment Product were, 104 g (1 mol) of triethylenetetramine dissolved in 1 l of ethanol and on 70 ° C heated. To this solution, 92 g (1 mol) of epichlorohydrin was added dropwise and the reaction mixture was refluxed for 2 hours. Thereafter was cooled to 70 ° C and the solution used for further processing.

The 70 ° C. solution was added dropwise over the course of one hour 488 g (4 mol) of propane sultone were added and the mixture was stirred for 30 minutes. According to this, 160 g (4 mol) of sodium hydroxide dissolved in water were added with stirring. After that were 660 g (4 mol) of sodium chloroxypropanesulfonic acid dissolved in 1.4 l of water of the mixture admitted. The reaction mixture was then refluxed for 2 hours. Thereafter, the solution was concentrated in vacuo and the residue in water to a 20% solution added.

This solution was used as an additive in the following Zinkba, d: 250 g / l zinc sulfate crystallizes 10 g / l sodium chloride 20 g / l boric acid 4 g / l thiourea 5 ccm / l of the aforementioned solution. The pH of the bath was 4.5. With the bathroom were good at an operating temperature of 15-30 ° C in the current density range of 2 - 8 A / dm² receive shiny zinc deposits of sufficient ductility and depth scattering.

Example 6 First of all, according to Example 5, a reaction product was produced Equimolar amounts of triethylenetetramine and epichlorohydrin prepared. To the 70 ° C warm solution, 368 g (4 moles) of epichlorohydrin were added dropwise over the course of one hour given and the reaction mixture was then refluxed for 1 hour. The solution was then concentrated in vacuo and the residue with water to a 20% solution added. This solution was used as an additive for the following Zinc bath used: 300 g / l zinc sulfate crystallizes 20 g / l boric acid 2 g / l thiourea 0.8 g / l cadmium sulfate crystallizes 3 ccm / l of the aforementioned solution The pH was 2.5. The bath delivered at an operating temperature of 15-300C in the current density range of 1 - 8 A / dm2, good glossy, ductile zinc precipitates with very good depth of shine.

Example 7.

To the 70 C warm solution of the corresponding Example 5 prepared Reaction product of equimolar amounts of triethylenetetramine and epichlorohydrin were given 544 g (4 mol) of butane sultone in the course of one hour. Then another hour stirred at 800C. The solution was then concentrated in vacuo and the The residue was taken up in water to form a 20% solution. This solution was called Additive used for the following zinc bath: 200 g / l zinc sulfate crystallizes 20 g / l boric acid 2. g / l thiourea 3 ccm / l of the aforementioned solution The pH of the Bath was 35 With the bath was at an operating temperature of 15-300C in the current density range from 2 - 8 A / dm² a shiny, ductile zinc deposit with sufficient Maintain depth scatter.

Example 8, to the 70 ° C warm solution of the corresponding example 5 produced reaction product of equimolar amounts of triethylenetetramine and epichlorohydrin 267 g (3 mol) of glycol chlorohydrin were added to 1 l of water. The reaction mixture was then refluxed for 2 hours. Then 160 g (4 mol) of sodium hydroxide in aqueous solution were added with stirring. After addition Another 267 g (3 mol) of glycol chlorohydrin, the solution was refluxed for 2 hours cooked. The solution was then concentrated in vacuo and the residue in water added to a 20% solution. This solution was used as an additive according to the invention Used in a standing zinc bath: 300 g / l zinc sulfate crystallizes 30 g / l boric acid 2 g / l thiourea 0.5 g / l cadmium sulfate crystallizes 10 ccm / l of the aforementioned solution The pH of the bath was 4.5. The bath delivered at operating temperature from 15-300C in the current density range of 1 - 8 A / dm2, good glossy, ductile zinc deposits with sufficient depth scattering.

Example 9 To make that used in the present example 75 g (1 mol) of diethylenetriamine were dissolved in 1 l of water and heated to 70.degree warmed up. 128 g (1 mol) of 1,3-dichlorohydrin were slowly added to this solution The reaction mixture was heated to boiling under reflux for 2 hours. Thereafter was cooled to 700C and the solution was processed further.

366 g (3 mol) of propane sultone were added dropwise to the 70 ° C. solution added im Laure for one hour and then the mixture was stirred at 80 ° C. for 1 hour. The reaction solution was then concentrated in vacuo and the residue to a 20% aqueous solution dissolved.-This solution was used as an additive in the following Zinc bath used: 300 g / l zinc sulfate crystallizes 30 g / l boric acid 1 g / l thiourea 0.5 g / l cadmium sulfate crystallizes 5 ccm / l of the above mentioned solution 0.5 g / l Isononyl sulfate The pH of the bath was 2.7. The bath delivered at operating temperature from 15-50 ° C in the current density range of 1 - 8 A / dm2 shiny, ductile zinc deposits with sufficient depth scattering.

Example 10 To a solution of 60 g (1 mol) heated to about 700C Xthylenediamine in 1 1 of ethanol were added dropwise 92 g (1 mol) Epichlorohydrin given and the reaction mixture was then refluxed for 2 hours heated to boiling.

To the solution cooled to 70 ° C., 244 g (2 mol) of propane sultone were added added dropwise and the mixture was stirred at 80 ° C. for 1 hour. Thereafter the reaction solution was concentrated in vacuo and the residue in water to a 2O, igen solution added. This solution was used as an additive in the following zinc bath used: 250 g / l zinc sulfate crystallizes 10 g / l sodium chloride 20 g / l boric acid 0.5 g / l cadmium sulfate crystallizes 2 g / l thiourea 5 ccm / l of the above Solution 0.5 g / l isohexyl sulfate The pH of the bath was 3. With the bath were at an operating temperature of 15-300C in the current density range of 1 - 6 A / dm2 good receive shiny, ductile zinc precipitates with sufficient depth scattering.

Example 11-To make that used in the example below 75 g (1 mol) of diethylenetriamine were dissolved in 1 l of ethanol and heated to 70.degree warmed up. 116 g (1. mol) of 1,6-dichlorohexane were slowly added to this solution and the reaction mixture was heated to boiling under reflux for 2 hours. To Cooling to 70.degree. C., 348 g (3 mol) of sodium chloroacetate were added and the mixture became Stirred at 80 ° C. for 1 hour. Afterward was the solution with 120 g (3 mol) of sodium hydroxide in aqueous solution in the course offset by 30 minutes. It was then concentrated in vacuo and the residue in water added to a 20% solution, which was used as an additive for the zinc bath below Served: 300 g / l zinc sulfate crystallized 30 g / l boric acid 2 g / l thiourea-f-0.5 g / l cadmium sulphate crystallizes 10 ccm / l of the aforementioned solution 0.5 g / l isohexyl sulphate r-The pH of the bath was 4.5. The bath delivered at operating temperature from 15-) 0 ° C in the current density range of 1 - 6 A / dm² shiny, ductile zinc deposits with sufficient depth scattering.

Example 12 To a solution of 75 g (1 mol) heated to about 70 ° C Diethylenetriamine in 1 l of ethanol was slowly added to 214 g (1 mol) of 1,4-dibromobutene and the mixture was refluxed for 2 hours. After cooling down at 70 ° C., 366 g (3 mol) of propane sultone were added dropwise to the solution and Stirred at 80 ° C. for 1 hour. It was then concentrated in vacuo and the residue taken up in water to a 20% solution, which can be used as an additive for the following Zinc bath served: 300 g / l zinc sulfate crystallizes 30 g / l boric acid 2 g / l thiourea 0.5 g / l cadmium sulfate crystallizes 5 ccm / l of the aforementioned solution 0.5 g / l isohexyl sulfate. The pH of the bath was 3. With the bath, were at one Operating temperature of 15-30 0C in the current density range of 1 - 8 A / dm2 good glossy, Receive ductile zinc precipitates of sufficient depth.

Example 17 To a solution of 5 g (~ 1/20 mol) of triethylenetetramine 4 g (1/20 mol) of diepoxybutane were added to 200 cc of ethanol and the solution was Heated to boiling under reflux for 1/2 hour. After cooling to 70 0C, the 25 g (1/20, mol) of propane sultone are added dropwise to the solution, and for 1 hour 800C stirred. It was then concentrated in vacuo and 'the residue in Water added to a 20% solution, which is used as an additive in the following Zinc bath was used: 300 g / l zinc sulfate crystallized 20 g / l boric acid 2 g / l Thiourea 0.5 g / l cadmium sulfate crystallizes 5 com / l of the aforementioned solution 0.5 g / l isohexyl sulfate The pH of the bath was 3-.0. The bath delivered to one Operating temperature of 15-30 ° C in the current density range of 1 - 8 A / dm2 good glossy, ductile zinc coatings with good depth dispersion.

Claims (7)

Claims Acid galvanic bright zinc bath with a content of soluble zinc salts, optionally further conductive salts in addition to customary brighteners and wetting agents, thereby characterized in that there are also derivatives of polymer or oligomeric reaction products equimolar amounts of alkylene polyamines and aliphatic α, # - bifunctional Contains alkylating agents with 3 to 8 carbon atoms in a straight chain, the substituted on the nitrogen atoms by aliphatic radicals having 1 to 4 carbon atoms which can carry hydroxyl, carboxyl or sulfonic acid groups. 2. Acid galvanic zinc bath according to claim 1, characterized in that that there are derivatives of polymer or oligomeric reaction products of equimolar amounts of alkylene polyamines and contains epichlorohydrin. 3. Acid galvanic zinc bath according to claim 1 and 2, characterized in that that it contains derivatives of alkylenepolyamine reaction products based on total nitrogen calculated to have 1-2 substituents per nitrogen atom. 4. Acid galvanic zinc bath according to claim 1 ") 3, characterized in that that it contains derivatives of alkylene polyamine reaction products in which the Carboxyl or sulfonic acid groups on the nitrogen atoms carry. 5. Acid galvanic bright zinc bath according to claim 1 - 4 4 thereby characterized in that it contains the derivatives of the alkylenepolyamine reaction products in one Contains a concentration of 0.01-10 g / l, preferably 0> 1-2 g / l bath liquid. 6. Acid galvanic bright zinc bath according to claim 1 - 5, characterized in that that there is a further addition of thiourea in a concentration of 0.5 - 3 g / l Contains bath liquid. 7. Acid galvanic bright zinc bath according to claim 1 - 5, characterized in that that there is a further addition of cadmium salts in a concentration of 0.02-0.5 g / l Contains bath liquid. 8o acidic galvanic bright zinc bath according to claims 1 - 6, characterized in that that it is used as a wetting agent with short-chain branched alkyl sulfates in an amount of 0.5 - contains 1 g / l bath liquid,