DE1922689A1 - Acid galvanic bright zinc bath - Google Patents

Description

Hang! & Cie GmbH Düsseldorf, April 51, 1969

Patent department at Henkelstrasse 67

Z / Gr.

New patent application D 38IO

Acid galvanic bright zinc bath

Most of the bright zinc baths used in practice still work in the alkaline range today. Among the ' In alkaline baths, in turn, the cyanidic bright zinc baths play the greatest role. Albeit detoxifying the The resulting wastewater is no longer a technical problem, it is nevertheless a cost factor there is always cause for criticism of this type of bathroom. There has therefore been no lack of attempts to use the cyanidic bright zinc baths to be replaced by other types of baths.

In addition to cyanide-free alkaline zinc baths, acidic zinc baths were developed for this purpose, in which the wastewater without Difficulty and greater expense can be eliminated. Besides this advantage of the easy disposal of the sewage However, the acidic zinc baths have a number of disadvantages that make them unsuitable for extensive industrial use appear. In some baths, for example, the precipitation is dull, and if it is successful, the precipitation To add shine, their depth scattering still leaves a lot to be desired and the current density range in which shiny precipitates are obtained remains very narrowly limited. In addition, show the precipitates obtained

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often a strong embrittlement. Despite all efforts, it is it was not possible to effectively counter all disadvantages at the same time, rather, only limited and one-sided improvements are always achieved, which often enough reinforce a other disadvantage. There is therefore still the desire for an acidic bright zinc bath that over a wide range of current densities that shine well and are free of embrittlement Provides precipitation with good depth dispersion.

It has now been found that these requirements can largely be met if an acidic galvanic bright zinc bath with a content of soluble zinc salts, optionally other conductive salts, is used in addition to customary brightening and wetting agents which also contain reaction products of amidoamines, which are formed by condensation of aliphatic, saturated or unsaturated mono- and / or dicarboxylic acids are obtained with 4-18 carbon atoms with AlkylenpoIyaminen, having carboxyl or sulfonic acid groups containing Alkylierungsmifceln, wherein per basic nitrogen atom from 0.5 to 2.5 moles, preferably 1 to 2.4 moles, alkylating agents for Use contains.

Aliphatic monocarboxylic acids which are suitable for the preparation of the amidoamines to be alkylated are, for example, butter, valerian, caproone, caprylic, pelargon, capric, lauric, myristic, palmitic, stearic, crotonic, undecylene -, oleic, linoleic and linolenic acids. The aliphatic dicarboxylic acids which are suitable for the preparation of the amidoamines to be alkylated are succinic, glutaric, adipic, pimelic, cork, azelaic, sebacic, nonanedicarboxylic, and maleic and itaconic acids.

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For the production of the amidoamines to be alkylated come as alkylene polyamines primarily low molecular weight polyamines, such as ethylene diamine, propylene diamine, diethylene triramine, Triethylenetetramine and tetraethylenepentamine in question.

The desired amidoamines are produced by condensation of the corresponding mono- or dicarboxylic acid with the alkylene polyamine in a manner known per se. Here, the molar ratio is to be chosen so that in addition to the amide groups at least one capable of reacting with the alkylating agent; Amino group is retained. The amidoamines obtained in this way can be both monomeric and polymeric Be nature. In many cases it will be expedient to use an excess of alkylenepolyamine after completion or is distilled off during the reaction. The amidoamines obtained are then mixed with the alkylating agent implemented for substitution on the nitrogen atoms, with 0.5 to 2.5 mol per basic nitrogen atom, preferably 1-2.4 mol, are used and the reaction is optionally carried out in the presence of proton acceptors will.

Suitable alkylating agents are e.g. chloroacetic acid, chloropropionic acid, chlorosuccinic acid, bromoethanesulphonic acid, Chlorohydroxypropane sulfonic acid, propane sultone and butane sultone to call.

The amidoamines obtained in the condensation of mono- or dicarboxylic acids with the alkylene polyamines have, depending on Type of acid used and the molar ratio of the condensation partners in addition to the unreacted, predominantly secondary amino groups, there are also primary amino groups. Through more Reaction with the alkylating agents, depending on the amount of these used, in addition to the

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formation of tertiary nitrogen atoms sometimes also lead to the formation of quaternary nitrogen atoms. Good solubility in water is guaranteed, even for products with exclusively tertiary nitrogen atoms, that the Products are generally used as sodium salts.

Those derivatives of the above-mentioned amidoamines for their preparation are of particular importance Nitrogen atom 1-2.4 mol of chloroacetic acid or propane sultone were used. With such products you can have a particularly favorable effect on the totality of the properties of the zinc precipitate.

The application concentration of the to be used according to the invention Amidoamine derivatives are between 0.01 and 10 g per liter, preferably 0.05 to 2 g / l bath liquid, ·

2 The applicable current densities are in the range of 1-8 A / dm at a bath operating temperature of 10-40 ° C., preferably 15-3O ⁰ C. The baths are generally operated in the pH range of 4-5.

The effect of the products used according to the invention is significantly increased by the simultaneous addition of thiourea to the baths. The application concentration Thiourea is generally between 0.5-3 g / l bath liquid.

A further improvement in the deposited zinc precipitates can be achieved by adding cadmium to the bath. The yellow tinge of the zinc precipitate that occurs in some bath compositions is due to the addition of cadmium into a blue cast and the precipitate is preserved thereby brilliance. In addition, the addition of cadmium can in some cases reduce the depth scattering of the

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Influence the bath positively. The amount of cadmium salts added moves in the range of 0.02 - 0 ^ 5 g / l bath liquid.

Suitable as wetting agents for the bright zinc bath according to the invention primarily short-chain branched alkyl sulfates or sulfonates, such as isohexyl, isononyl sulfate or isohexyl sulfonate, priority should be given to sulphates. Are the reaction products of the amidoamines used according to the invention with alkylating agents containing carboxyl or sulfonic acid groups only present in very small amounts, longer-chain alkyl sulfates such as e.g. lauryl sulfate, have been 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 explain the subject matter of the present invention in more detail without restricting it to them.

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example 1

To prepare the product used in the present example, 146.0 g (1 mol) of adipic acid and 756 g (4 mol) of tetraethylene pentamine were combined and heated with stirring and introduction of nitrogen. At 190 ⁰ C. bottom temperature, the condensation reaction ensued. After 2V2 hours, 40 g water which contains about $ 8 amine had formed and the bottom temperature was raised to 220 ⁰ C. The excess amine was then distilled back, and 598 g went over at bp ^, 140 ° C, which resulted in 2.1 mol.

o, χ

speaks. The molar ratio of adipic acid to tetraethylene pentamine was accordingly about 1: 1.9 in the amidoamine obtained. 464 g of a yellow, viscous substance were obtained.

46.4 g of the amidoamine obtained were dissolved in 250.0 g of water and heated to 50.degree. 206 g (1 ^ 69 mol) of propane sulfon were added dropwise to this solution with stirring over the course of 3.5 hours, ie approximately 2.25 mol of alkylating agent per basic nitrogen atom. With this amount of propane sultone it is possible to quaternize most of the basic nitrogen atoms of the amidoamine. The mixture was then subsequently stirred at 50 ^° C. for a further 1 hour. The solution was then adjusted to pH 7 with 5% sodium hydroxide solution. In this way, a 50% solution of the sodium salt of the amidoamine substituted by to-propanesulfonic acid residues on the basic nitrogen atoms and largely quaternized was obtained. This solution was used as an additive for the zinc bath below.

300 g / l zinc sulfate crystallizes 30 g / l boric acid

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2 g / l thiourea.

5 g / l cadimium sulphate crystallizes 2 ccm / l of the above solution
0 * 5 g / l isononyl sulfate

The pH of the bath was 4.5 x The bath delivered at one Operating temperature of 15-3O ° C in the current density range of 1-8 A / dm shiny, ductile zinc coatings with sufficient leveling for many cases.

Example 2

46.4 g of the amidoamine prepared in Example 1 were dissolved together with 78 g (0.93 mol) of sodium bicarbonate in 200 ml water and heated to 7O ⁰ C. In the course of 2 hours, a solution obtained by neutralizing 88 g (0.93 mol) of chloroacetic acid with 37/2 g (0.93 mol) of sodium hydroxide in 200 ml of water was added. This amount corresponds to the use of about 1.24 moles of alkylating agent per basic nitrogen atom. The batch was then subsequently stirred at 80 ^° C. for 2 hours. An approximately 30% solution of the sodium salt of the amidoamine substituted by acetic acid residues on the basic nitrogen atoms was obtained. The solution was used as an additive for the zinc bath below.

300 g / l zinc sulfate crystallizes 20 g / l boric acid

2 g / l thiourea '
2 ccm / l of the above solution
0> 5 g / l isononyl sulfate

The pH of the bath was 4.5 · The bathroom provided at an operating temperature of 15-30 ⁰ C in the current density range of 1-8 A / dm gl
Leveling.

8 A / dm shiny, ductile zinc precipitates with massive

Example 3

The product required for the subsequent experiment was obtained in the following way. 146.0 g (1 mole) of adipic acid and 756 g (4 moles) Teträäthylenpentamin were combined and heated with stirring and introduction of nitrogen to 190 ⁰ C. After 39.5% of water had been formed in the course of the condensation reaction and still contained small amounts of amine, redistillation of the amine was started. At Kp _T

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14o C 476 g of tetraethylene pentamine were distilled back, which corresponds to about 2.5 moles. The molar ratio of adipic acid to tetraethylene pentamine was in the amidoamine obtained therefore about 1: 1.5 · 385 g of a fawn, viscous mass obtained. ,

38.5 g <äes amidoamine obtained were overall in 183 ml of water, dissolved and heated to 50 ⁰ C. In this solution were slow

g (I * 19 mol) propane sultone added dropwise, i.e. per basic Nitrogen atom approximately 2.15 moles of alkylating agent. The mixture was then stirred at 50 ° C. for a further 1 hour. After that, the Solution adjusted to pH 7 with 50% sodium hydroxide solution. It was a 50 $ solution of the sodium salt of the substituted amidoamine obtained which was used as an additive for the zinc bath below.

200 g / l zinc sulfate crystallizes 20 g / l boric acid

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20 g / l magnesium sulfate crystallized

2 'g / l thiourea
2 ccm / l of the above solution
0.5 g / l isononyl sulfate

The pH of the bath was 4.8. The bathroom delivered at one

Operating temperature of 15-3O ° C in the current density range of Ιο

8 A / dm glossy, ductile zinc coatings with good leveling.

Example 4

J58,5 g of according to Example> amidoamine prepared were mixed together with 50 * 5 g (0 * 6 mol) of sodium bicarbonate in 155 ml of v / ater and heated to 70 ⁰ C. A solution obtained by neutralizing 57 g (0 * 6 mol) of chloroacetic acid with 24 g (0.6 mol) of sodium hydroxide in 185 ml of water was then slowly added dropwise. This amount corresponds to the use of about 1.1 mol of alkylating agent per basic nitrogen atom. The batch was then stirred at 80 ° C. for 2 hours. A 25% solution of the sodium salt of the amidoamine substituted by acetic acid residues was obtained, which was used as an additive for the subsequent zinc bath.

200 g / l zinc sulfate crystallizes 20 g / l boric acid

20 g / l magnesium sulfate crystallized

2 g / l thiourea "■
4 ccm / l of the above solution
0.5 g / l isononyl sulfate

The pH of the bath was 5. The bath delivered at an operating temperature of 15-JO ⁰ C in the current density range of

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2-8 A / dm shiny, ductile zinc coatings with sufficient leveling for most cases.

Example 5

146.0 g (1 mole) of adipic acid and 756 g (4 moles) Tetraathylenpentamin were added together for the production of the product used for this example, and heated with stirring and introduction of nitrogen to 190 ⁰ C. In the course of about 2/2 hours 39 ml of water containing approx. 5 g of amine were deposited. At Kp ■, 1 * K) ^O C, 560 g of tetraethylene pentamine were redestilo> J- -

lated, which corresponds to 2.96 moles. The molar ratio of adipic acid to tetraethylene pentamine was about 1: 1 in the amidoamine obtained. 505 g of a light brown, solid body were obtained.

30.5 S of the amidoamine obtained were heated with lo4 ml of water at 50 ⁰ C and then 86.5 g (0.71 mol) of propane sultone was added dropwise over the course of 2 hours with stirring, ie per basic nitrogen atom about 2.35 moles of alkylating agent . The mixture was then subsequently stirred at 50 ^° C. for a further 1 hour. Thereafter, the solution with 50 $ ig ^e r was set sodium hydroxide solution to 7 and the PTT thus obtained 50 $ strength by weight solution of the sodium salt of the amido amine derivative used as additives for the below-mentioned zinc bath.

300 g / l zinc sulfate crystallizes 20 g / l boric acid

1 g / l thiourea
1 ccm / 1 of the above solution
0.8 g / l lauryl sulfate

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The pH of the bath was 4.8. The bath delivered at an operating temperature of 15-30 C in the current density range of 1-8 A / dm well-shining, very ductile zinc precipitates with sufficient leveling.

Example 6

98 g (1 mol) of maleic anhydride and 756 g of tetraethylenepentamine were heated with stirring and introduction of nitrogen to 190 ⁰ C. In the condensation reaction 19.5% of water were formed. Then 380 g, about 2 moles of tetraethylene pentamine were redistilled under reduced pressure. The molar ratio of maleic acid to tetraethylene pentamine was accordingly 1: 2 in the amidoamine obtained. 455 g of a brown, viscous mass were obtained.

45 * 5 g of the amidoamine obtained were heated at I80 g of water at 50 ⁰ C. Ij54 g (1.1 mol) of propane sultone were added to the solution with stirring over the course of 2/2 hours. From this a ratio of approx. 1.4 mol of propane sultone per basic nitrogen atom can be calculated. After stirring at 50 ° C. for a further hour, the solution was adjusted to pH 7 with 50% sodium hydroxide solution. The 50% solution of the corresponding sodium salt obtained in this way was used as an additive for the following zinc bath.

500 g / l zinc sulfate crystallizes 20 g / l boric acid

1 g / l thiourea
0.5 g / l cadmium sulfate crystallizes 0.5 ccm / l of the above solution
0.7 g / l octyl sulfate

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The pH of the bath was 4.8. The bath delivered at an operating temperature of 15-30 ⁰ C in the current density range of 1-

8 A / dm bare, see
digender leveling.

8 A / dm bright, very ductile zinc precipitates with frie

Example 7

45 > 5 g of the amidoamine prepared according to Example 6 were dissolved together with 92 g (1 * 1 mol) of sodium hydrogen carbonate in 200 g of water and heated to 70.degree. In the course of 2 hours, a solution obtained by neutralizing Io4 g (1.1 mol) of chloroacetic acid with 44 g (1.1 mol) of sodium hydroxide in 35 ° ml of water was added, ie the calculated ratio of alkylating agent per basic nitrogen atom was 1.4: 1. The batch was then stirred at 80 ° C. for 2 hours. A 25% solution of the corresponding sodium salt was obtained, which was used as an additive for the zinc bath below.

300 g / l zinc sulfate crystallizes 30 g / l boric acid

2 g / l thiourea

0.5 g / l cadmium sulfate crystallizes 4 ccm / l of the above solution 0.5 g / l isohexyl sulfate

The pH of the bath was 4.5. At an operating temperature of 15-3O ° C in the current density range of 1-

8 A / dm glossy, ductile zinc coatings with one for many Cases of sufficient leveling.

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■ Example 8

98 g (1 mol) of maleic anhydride and 756 g (4 moles) of tetraethylenepentamine were added together and heated with stirring and introduction of nitrogen to "190 ⁰ C. In the course of condensation reaction, 20 g of water were then deposited were distilled back 455 S tetraethylenepentamine under reduced pressure. The molar ratio of maleic acid to tetraethylene pentamine in the amidoamine obtained was 1ί1 * 5 · 379 g of a dark brown, viscous mass were obtained.

37 x 9 g of the amidoamine obtained along with 125 g Water was heated to 50 C and the solution was slow 86.5 g (0.71 mol) of propane sultone were added dropwise, ie. there were Approximately 1.3 moles of alkylating agent are used per calculated basic nitrogen atom. After an hour The solution was subsequently stirred at 50 ° C. with 50% sodium hydroxide solution adjusted to pH 7. The 50 $ solution of the corresponding Sodium salt was used as an additive to the zinc bath.

300 g / l zinc sulfate crystallizes 20 g / l boric acid

1 g / l thiourea

0.5 g / l cadmium sulfate crystallizes. 2 cc / l of the above solution 0.5 g / l isononyl sulfate

The pH of the bath was 4.8. The bathroom delivered at "one

Operating temperature of 15-3O ° C in the current density range of Ιο
8 A / dm shiny, ductile zinc coatings with sufficient

Leveling

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Example 9

98 g (1 mol) of maleic anhydride and 756 g (4 mol) of tetraethylene pentamine were, as in the previous examples, condensed with separation of 19 g of water. Afterward 567 g of tetraethylene pentamine (3 mol) were distilled back. The molar ratio of maleic acid to tetraethylene pentamine in the amidoamine obtained was 1: 1. There were 268 g of a black j, solid mass obtained.

26.8 g of this mass were heated to 50 ° C. with 100 g of water and 73 g (0 * 59 mol) of propane sultone were slowly added dropwise to this solution, an amount corresponding to 2 mol of alkylating agent per calculated basic nitrogen atom. After stirring for one hour at 50 ⁰ C the solution of 50 $ aqueous sodium hydroxide solution to pH 7 has been set. The 50% solution of the corresponding sodium salt was used as an additive in the following zinc bath.

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
3 ccm / l of the above solution
0.5 g / l isohexyl sulfate

The pH of the bath was 4.5, the bath delivered at an operating temperature of 15-3O ⁰ C in the current density range of 1-

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8 A / dm good glossy, ductile low-grade zinc layer with a satisfactory Leveling.

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Example 10

144 g (1 mol) of caprylic acid were mixed with 146 g (1 mol) of triethylenetetramine Heated to 180-190 ° C for two and a half hours, woloei 17> 5 g of water were deposited. After cooling to 50 ° C the amidoamine obtained was diluted with 950 nil water

J> 66 g (3 mol) of propane sultone were added dropwise to this solution at room temperature in the course of 3 hours, which corresponds to the use of 1 mol of alkylating agent per basic nitrogen atom. The solution was naehgerührt further 1 hour at 50 ⁰ C and used in that about 40 $ by weight concentration as an additive to the zinc bath.

5OO g / l zinc sulfate crystallizes 30 g / l boric acid

1 g / l thiourea

0.5 g / l cadmium sulfate crystallizes 3 ccm / l of the above solution
0.5 g / l isohexyl sulfate

The pH of the bath was 3 x The bath delivered at one Operating temperature of 15-3O ° C in the current density range of 1-8 A / dm shiny, very ductile zinc precipitates with sufficient leveling.

Example 11

280.4 g (1 mole) were LinoIsäure wherein Ib, 5 g of water were obtained with 146 g (1 mole) of tri-äthylentetramin 2 ^X / 2 hours at 190 ° C heated. After cooling to 50 ⁰ C, the Ar.idoamin obtained with 1200 ml of water was diluted and this solution was added dropwise at room temperature over the course of 3 hours 366 g (3 moles) of propane sultone,

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according to a use of 1 mole of alkylating agent per basic nitrogen atom, the solution for 1 hour at 50 ⁰ C was stirred and used in that about 40 $ by weight concentration as an additive to the zinc bath.

JOG g / l zinc sulfate crystallizes 20 g / l boric acid

2 g / l thiourea

2 g / l di-o-toluene sulfonamide
2 ccm / l of the above solution
0 * 5 g / l isononyl sulphate

The pH was 4. The bath provided at an operating temperature of 15-30 ⁰ C in the current density range of 1-8 A / dm good glossy, very ductile zinc deposit having a satisfactory leveling.

Example 12

To make the product used for this example were 202 g (1 mol) of sebacic acid with 584 g (4 mol) of triethylenetetramine combined and heated to 190 ° C. for 3 hours while stirring and passing in nitrogen. While 40 g of water with a small amount of amine were separated off during the condensation reaction. Now there were 564 g of triethylenetetramine distilled back, which corresponds to 2.5 mol. The molar ratio of sebacic acid to triethylenetetramine was accordingly in the amidoamine obtained about 1.5. There were 580 g obtained a light brown, viscous mass.

38.0 g of the amidoamine obtained were heated with 90 ml of water at 50 ⁰ C and were then with stirring in

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49 g (0.4 mol) of propane sultone were added dropwise over the course of 1 hour, ie 1 mol of alkylating agent per basic nitrogen atom. The mixture was then further 1 hour at 5O ⁰ C nachgerührt.- Thereafter, the solution of 50 $ aqueous sodium hydroxide solution to pH 7 was stopped and the solution of the sodium salt of the Amidoaminderivates used as additives for the following zinc bath.

200 g / l zinc sulfate crystallizes
10 g / l aluminum sulfate crystallizes

5 g / l sodium chloride
10 g / l boric acid

2 g / l thiourea
1 ccm / l of the above solution
1 g / l isononyl sulfate

The pH of the bath was 4.8. The bathroom delivered at one Operating temperature of 15- \ 30 ° C in the current density range of 1-

6 A / dm good glossy, ductile zinc coatings with massive
Leveling. ^-i

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Claims (6)

Claims 1.) Acid galvanic bright zinc bath with a content of soluble zinc salts, optionally other conductive salts in addition to customary brighteners and wetting agents, characterized in that there are additional reaction products of amidoamines, which by condensation of aliphatic, saturated or unsaturated mono- and / or) dicarboxylic acids with 4-18 carbon atoms are obtained with alkylene polyamines, with alkylating agents containing carboxyl or sulfonic acid groups, 0.5 to 2.5 mol, preferably 1 to 2.4 mol, of alkylating agent being used per basic nitrogen atom. 2. Acid galvanic bright zinc bath according to claim 1, characterized characterized in that it contains reaction products of amidoamines per basic nitrogen atom Have calculated 1-2.4 acetic acid or propanesulfonic acid residues. * J). Acid galvanic bright zinc bath according to claims 1 and 2, characterized in that it contains the reaction products of the amidoamines in a concentration of 0.01-10 g / l, preferably 0.05-2 g / l, bath liquid. 4. Acid galvanic bright zinc bath according to claims 1-3, characterized in that it is used as a further additive Thiourea in a concentration of 0.5-3 g / l Contains bath liquid. - 19 - 009846/1501 5. Acid galvanic bright zinc bath according to claims 1-4, characterized marked that it is cadmium salts as a further additive a concentration of 0.02 - 0.5 s / l bath liquid s thait. 6. Acid electrolytic bright zinc bath according to claims 1-5 > ; 'characterized in that it contains short-chain branched alkyl sulfates as a wetting agent in an amount of 0.5-1 g / l bath liquid. Henkel & Cie. GmbH. iV (Dr Haas) 0098A6 / t501