JPS619593A - Acidic electrolytic zinc plating bath - Google Patents

Abstract

PURPOSE:To obtain the titled plating bath in which a lustrous plated surface and soft plating are formed with excellent electrodeposition porperties in the range of broad current density by containing polyethyleneimine-modified substance of specified structure in the bath containing zinc ion and chlorine ion. CONSTITUTION:Polytheyleneimine-modified substance having the structure shown by a formula is contained in 0.1-20g/l proportion into an acidic electrolytic zinc plating bath containing zinc chloride and ammonium chloride or the like. In the formula, R is a reaction produce obtained by allowing aldehyde to react, hydrogen, hyrdoxyethyl, hydroxypropyl or the like and (n) shows 10-15 integer. The lustrous plated zinc is obtained with excellent covering power with this plating bath. Furthermore, since the pH range is broad and the permissible range of a lustering agent can be made large, the bath control becomes easy.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention provides zinc chloride with ammonium chloride or zinc chloride, potassium chloride and boric acid as main ingredients with a pH of 3.0 to 7.
This invention relates to an acidic zinc electroplating bath characterized in that zinc plating is carried out by reacting polyethyleneimine with aldehyde or further reacting with alkylene halohydrin to contain a modified brightener in the zinc plating bath. be.

<Problems to be Solved by the Invention> The present invention provides a glossy plated surface over a wide current density range;
A method of obtaining bright zinc plating with easy bath management by soft plating, good uniform electrodeposition and good covering power, wide pn range, and wide tolerance range for brighteners. It provides:

Basically, even if only one type of reaction product of polyethyleneimine and aldehyde is used, zinc chloride and ammonium chloride or zinc chloride,
A glossy electrodeposited surface can be obtained by adding potassium chloride and boric acid to a plating bath as main ingredients, but additional additives can be added to improve the physical properties.

Additives for acidic zinc baths include surfactants, amine compounds, aldehydes, ketones, and others, and various examples of their addition have been reported.

Most surfactants are nonionic, and useful types include β-naphthol polyethylene oxide, nonylphenol polyethylene oxide, polypropylene oxide, polyethylene oxide, and blockpo! Tsuma
, octylphenol polyethylene oxide, alkyl polyethylene oxide, etc. It is also possible to use anionic surfactants prepared by sulfonating these terminal hydride and rhoquine groups and neutralizing them with alkali hydroxide to achieve the desired effect.

Regarding amine compounds, polyethyleneimine-based polymers can provide a glossy surface over a wide current density range.

Aldehydes and ketones are brighteners in acidic zinc baths ranging from 0.01 g/Il to 2 g/j! used within the range. Effective aldehydes include benzaldehyde, vanillin, anisaldehyde, 〇-chloraldehyde, P-chloraldehyde, 〇-nitroaldehyde,
Furfural, biperonal salicylaldehyde, P-
) Aromatic aldehydes such as rualdehyde, veratrum aldehyde, and cinnamaldehyde. Furthermore, as a ketone, benzalacetone showed remarkable efficacy.

As other additives, hydrotropes such as sodium naphthalene sulfonate formalin condensate, sodium naphthalene sulfonate, sodium benzenesulfonate, benzoic acid, and sodium alkylbenzenesulfonate, and sulfur-containing compounds are also effective for increasing gloss. be.

The reaction between polyethyleneimine and aldehyde is the same, and there are cases where they are added or cross-linked.

When polyethyleneimine and aldehyde were added separately to an acidic zinc plating bath, a plated surface with brown, low-gloss areas was produced, but when polyethyleneimine and aldehyde were boiled and denatured by keeping it at reflux temperature and then denatured. produced a uniform, glossy plated surface. When aldehyde is added as a single ingredient, it is effective against aromatic aldehydes, but when reacted with polyethyleneimine, other aldehydes other than aromatic aldehydes such as formaldehyde, acetaldehyde, propionaldehyde, acrolein, crotonaldehyde, and furfural are also effective. Ta.

Since water solubility decreases when polyethyleneimine and aldehyde are reacted, for example, in the case of polyethyleneimine and benzaldehyde, the limit was 6:1 (weight ratio). If benzaldehyde is increased beyond this point, it will separate into two layers, making it necessary to add alcohol and causing oil droplets to form in the bath.

In order to increase the water solubility or to reinforce the effect, ethylene chlorohydrin, propylene chlorohydrin, propylene oxide, etc. may be additionally reacted.

[Production Example 1] Polyethyleneimine (Nippon Shokubai type spo
12) Seal 150 g of distilled water, 325 g of distilled water, and 25 g of benzaldehyde, stir, and raise the temperature.

When the reflux temperature is reached, the mixture is refluxed for 60 minutes and then cooled to obtain 500 g of a yellow homogeneous liquid. This is called polymer A.

[Production Example 2] 100 g of polyethyleneimine was placed in the 40 flask of Example 1.
, 300 g of distilled water was sealed and stirred to raise the temperature to 55°C. A solution of 50 g of reagent paper formalin and 100 g of distilled water is added dropwise. After dropping, keep at reflux temperature for 60 minutes, cool to 60°C, and add 50% ethylene chlorohydrin.
Drop g. Thereafter, the temperature was raised to reflux, and the mixture was refluxed and cooled for 60 minutes to obtain 500 g of a pale brown viscous liquid. This is referred to as polymer B.

[Comparative Example 1] Ingredients Concentration Zinc chloride 30g/j! Ammonium chloride 150g/j2 polyethyleneimine 2
g/l Benzaldehyde 0.8 g/1 Ejected under the above conditions at 25°C using an iron plate for Hull Cell made by Hon Plating Test Instruments.
2 A/d rrf After 5 minutes of plating, the plated surface became cloudy with many streaks.

<Example 1> Ingredients Concentration Zinc chloride 30 g/l Ammonium chloride 150 g/1 Polymer A
6g/j! Electrodeposition was performed at 25° C. and 2 A/dds using a Hull cell iron plate under the above conditions, and a mildly glossy plated surface was obtained.

<Example 2> Ingredients Concentration Zinc chloride 100 g/Il Ammonium chloride 200 g/1 polymer 87 g/j! Nonylphenol polyethylene oxide 5g/l Benzalacetone 0.1g/#alkylphenol polyethylene oxide sulfate sodium
0.5g/l under the above conditions using an iron plate for Hull cell.
After plating at 5° C. 2 A/dd for 5 minutes, a shiny plated surface was obtained.

<Example 3> Ingredients Concentration Zinc chloride 30g/l Ammonium chloride 150g//Polymer A
Log/Il polyethylene glycol 2000 10g/it sodium naphthalene trisulfonate Ig/potassium β-benzoate 2g/Il When plated at 25°C for 2A/dds using a Hull cell iron plate under the above conditions, a shiny plated surface was obtained. .

<Example 4> Ingredients Concentration Zinc chloride 100g/#Potassium chloride 200g/i! Boric acid 20g/It Polymer 8 5g/N octylphenol polyethylene oxide 5g/l Potassium benzoate 2g/p.

Salicylaldehyde Ig/z When plated at 25°C at 2A/drrrs using a Hull cell iron plate under the above conditions, a shiny plated surface was obtained.

<Effects of the Invention> As described above, the present invention provides a shiny plated surface over a wide range of current densities, soft plating, good uniformity of electrodeposition, good covering power, and a wide pH range that allows for brighteners to be used easily. By increasing the size, bath management becomes easier and glossy zinc plating can be obtained, which is of great industrial value.

Claims (1)

[Claims] Contains zinc ions and chloride ions, and has the general formula...
・・・▲There are mathematical formulas, chemical formulas, tables, etc.▼・・・・・・
(In the formula, R means an aldehyde produced as a result of a reaction or hydrogen or hydroxyethyl, hydroxypropyl, etc., and n means an integer from 10 to 50).
An acidic zinc electroplating bath capable of producing bright zinc plating, characterized in that it contains 1 to 20 g/l of a modified polyethyleneimine.