JP2001214293A - Alkaline zinc and zinc alloy plating bath - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an alkaline zinc and zinc alloy plating bath by which a plating film having good physical properties is obtained in uniform thickness even when the current density is changed. SOLUTION: The alkaline zinc and zinc alloy plating bath contains the water- soluble reactive product of (a) urea or thiourea and (b) a dialkylaminoalkylamine with (c) a dichloroalkyl ether and (d) an epihalohydrin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a plating bath for electrodepositing shiny zinc or zinc alloy on various substrates.
The present invention relates to a brightener for use in the plating bath and a plating method using the plating bath.

2. Description of the Related Art In recent years, while environmental measures have been called for, zinc plating has shifted from plating baths using bluish soda to zincate baths using caustic soda for easy wastewater treatment. Technical developments on the technology are also progressing. In the zincate bath, since the properties of the plating film largely depend on the brightener, the uniformity of the plating film was not improved with the existing brightener. As a method for solving the problem, JP-A-8-209379 and JP-A-11-193486
Japanese Patent Laid-Open Publication No. H11-163873 proposes a plating bath using a reaction product of dialkylaminopropylamine, urea, and dichloroalkyl ether as a main gloss component. Although the throwing power is improved compared to the case of using an agent, the accuracy of the plated product requiring more precision, such as a pressed product having a complicated shape or a cylindrical product, still has a large difference in film thickness due to the current density. It was difficult to obtain a uniform film thickness. Therefore, in practice, a film having a uniform film thickness is usually obtained by using an auxiliary anode.

[0002]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an alkaline zinc and zinc alloy plating bath which has good film properties even when the current density changes and provides a uniform plating film thickness. An object of the present invention is to provide a brightening agent for alkaline zinc and zinc alloy plating baths, which has good film properties even when the current density changes, and provides a uniform plating film thickness. Another object of the present invention is to provide an efficient plating method using the above plating bath.

[0003]

SUMMARY OF THE INVENTION The present invention provides a reactive product obtained by reacting (a) urea or thiourea, (b) dialkylaminoalkylamine and (c) dichloroalkyl ether with (d) epihalohydrin. The present invention has been made based on the finding that the use of a material as a brightener for alkaline zinc and zinc alloy plating baths can effectively solve the above-mentioned problems. That is, the present invention is characterized by containing a water-soluble reactive product of (a) urea or thiourea, (b) dialkylaminoalkylamine, and (c) dichloroalkyl ether with (d) epihalohydrin. An alkaline zinc and zinc alloy plating bath is provided. The present invention
Further, the present invention provides a brightening agent for an alkaline zinc and zinc alloy plating bath, characterized by containing the reactive product. The present invention also provides an alkaline zinc and zinc alloy plating method using the alkaline zinc and zinc alloy plating bath.

[0004]

DETAILED DESCRIPTION OF THE INVENTION Reactivity obtained by reacting (a) urea or thiourea, (b) dialkylaminoalkylamine and (c) dichloroalkyl ether with (d) epihalohydrin used as a brightener in the present invention. The product can be obtained, for example, by the following method. (A) 1 mol of urea or thiourea, (b) 2 mol of dialkylaminoalkylamine, (c) 0.1 to 1 mol of dichloroalkyl ether and (d) 0.1 to 1 mol of epihalohydrin, particularly ( The total amount of c) and (d) is preferably 0.5 to 1 mol, more preferably 1 mol, at a temperature of 90 to 170 ° C. for 1 to 10 hours so as to obtain a water-soluble reaction product. . The obtained reaction product preferably has a molecular weight of about 3000 to 100,000, and more preferably about 10,000 to 50,000. (B) As the dialkylaminoalkylamine, each alkyl group preferably has 1 to 6 carbon atoms, and more preferably 1 to 3 carbon atoms. Specifically, dimethylaminoethylamine, diethylaminoethylamine, dipropylaminoethylamine, dibutylaminoethylamine, dimethylaminopropylamine, diethylaminopropylamine, dipropylaminopropylamine, one or a mixture of two or more of dibutylaminopropylamine is used. preferable.

(C) As the dichloroalkyl ether, the alkyl group preferably has 1 to 6 carbon atoms.
More preferably, it is 1-3. Specifically, one or a mixture of two or more of dichloroethyl ether, dichloropropyl ether, and dichlorobutyl ether is preferable. (D) Epihalohydrin includes epichlorohydrin, epibromohydrin, and ethylenechlorohydrin.
Species or mixtures of two or more are preferred. The reaction product is preferably obtained by reacting (a) and (b) and then reacting (c) and (d), but (a) and (b) can be reacted simultaneously. In the present invention, the water-soluble reaction product is preferably contained in the plating bath in an amount of 0.1 to 50 g / L, more preferably 0.5 to 20 g / L. The alkaline zinc and zinc alloy plating bath of the present invention preferably contains 1 to 30 g / L, more preferably 5 to 20 g / L, in a form in which zinc is dissolved. It preferably contains an alkali metal hydroxide, for example, sodium hydroxide in an amount of 60 to 200 g / L, more preferably 90 to 150 g / L.
L.

[0006] The pH of the alkaline zinc and zinc alloy plating bath of the present invention is preferably 13 or more, more preferably 14 or more. Various additives can be contained in the alkaline zinc and zinc alloy plating baths of the present invention. For example, as silicate, colloidal silica,
It is preferable to contain 1 to 100 g / L of an alkali silicate such as No. 3 silicon, and more preferably 5 to 50 g / L. In the present invention, examples of the zinc alloy include an alloy of zinc and one or more metals such as iron, nickel, cobalt, and manganese. The amount of these metals is preferably about 0.1 to 60% by mass. When obtaining these alloy platings, it is preferable to change the metal ion concentration in the plating bath depending on the type of the alloy to be obtained and the alloy ratio. For example, for 5 to 20 g / L of zinc, 30 ~
1000 mg / L, nickel 0.02-5 g / L, cobalt 0.02-5 g / L, manganese 0.02-40 g / L
One or more of L and the like may be added. The metal ions are preferably supplied in the form of chloride or sulfate.

[0007] Preferably, a chelating agent is used to dissolve the metal salt. As chelating agents, citric acid,
Tartaric acid, gluconic acid, hydroxycarboxylic acids such as glycolic acid and salts thereof, monoethanolamine, diethanolamine, amino alcohols such as triethanolamine, ethylenediamine, diethylenetriamine,
Polyamines such as triethylenetetramine and tetraethylenepentamine, polyimines, polyamines and epihalohydrins (ethylene chlorohydrin, epichlorohydrin,
It is preferable to use a reaction product with epibromohydrin) or a halogen ether (dichloroethyl ether, dichloropropyl ether, dichlorobutyl ether). These can be used alone or in combination. These are preferably contained in the bath in an amount of 0.1 to 100 g / L, more preferably 1 to 50 g / L.

In the present invention, only the above-mentioned water-soluble reactant can be used as a brightener, but an auxiliary gloss component can also be added. For example, reaction products of aldehydes such as vanillin, benzaldehyde, hydroxybenzaldehyde, ethyl vanillin, veratraldehyde, anisaldehyde and nicotinic acid with halogenated hydrocarbons, alkylene oxides, epihalohydrins, halogen ethers and the like can be mentioned. In the present invention, the substrate to be plated (iron,
Copper, brass, etc.) as a cathode and a zinc plate or nickel as an anode, using the above-mentioned plating bath, for example, at a current density of 0.01 to 20 A / dm ² , at a temperature of 15 to 50 ° C. to a predetermined plating thickness. Until usually, for 5 to 80 minutes (eg,
A plating method including a plating step (plating thickness: 3 to 20 μm) is also provided.

According to the present invention, uniformity and uniformity can be improved as compared with the brightener used in the conventional alkaline zinc and zinc alloy plating baths.
Zinc and zinc alloy plating films with excellent film properties are obtained. Next, the present invention will be described with reference to examples.

[0009]

Example 1 1 mol of urea, 2 mol of dimethylaminopropylamine, 0.5 mol of dichloroethyl ether and 0.5 mol of epichlorohydrin were reacted at a temperature of 140 ° C. for 5 hours, and the molecular weight was 30,30. About 000 water-soluble reaction products were obtained (brightener A). 0.5 g / L of this brightener A, 10 g / L of Zn
A hull cell test was carried out at a total current of 2 A and a temperature of 25 ° C. for 20 minutes in a plating bath (pH 14 or more) containing water and 120 g / L of NaOH and the balance being water, using an iron plate as a cathode and a zinc plate as an anode. As a result, a galvanized film having good uniformity from the high current density part to the low current density part was obtained, which had better uniformity than the conventional brightener. Example 2 1 mol of urea, 2 mol of dimethylaminopropylamine, 0.5 mol of dichloroethyl ether and 0.5 mol of epibromohydrin were reacted at a temperature of 140 ° C. for 5 hours to obtain an aqueous solution having a molecular weight of about 35,000. An acidic reaction product was obtained (brightener B). 0.5 g / L of this brightener B and 10 g /
L, 120 g / L of NaOH, 0.005 g / L of 1-fluorohydroxy 3-carboxylate, the balance being water, in a plating bath (PH 14 or more), an iron plate as a cathode, a zinc plate as an anode, and A Hull cell test was performed at a current of 2 A and a temperature of 25 ° C. for 20 minutes. As a result, a galvanized film having good uniformity from the high current density part to the low current density part was obtained, which had better uniformity than the conventional brightener.

Example 3 1 mol of urea, 2 mol of dimethylaminoethylamine, 0.5 mol of dichloropropyl ether and 0.5 mol of ethylene chlorohydrin were reacted at a temperature of 140 ° C. for 5 hours.
A water-soluble reaction product having a molecular weight of about 30,000 was obtained (brightener C). 2 g / L of this brightener C and 10 g of Zn
Hull cell test was performed for 20 minutes at a total current of 2 A and a temperature of 25 ° C. in a plating bath (pH 14 or more) containing 120 g / L and 120 g / L of NaOH with the balance being water, using an iron plate as a cathode and a zinc plate as an anode. Was. As a result, a galvanized film having a uniform thickness from the high current density part to the low current density part was obtained, which was more uniform than the conventional brightener. Example 4 1 mol of urea, 2 mol of diethylaminopropylamine, 0.5 mol of dichloroethyl ether and 0.5 mol of propylene chlorohydrin were reacted at a temperature of 140 ° C. for 5 hours to obtain a water-soluble compound having a molecular weight of about 30,000. A reaction product was obtained (brightener D). 4 g / L of this brightener D, Zn 10
g / L, 150 g / L of NaOH, 0.5 g / L of 1-ethanol-hydroxy-3-carboxylate, the balance being water in a plating bath (PH 14 or more), an iron plate as a cathode, and a zinc plate as an anode. A Hull cell test was performed at a total current of 2 A and a temperature of 25 ° C. for 20 minutes. As a result, a zinc plating film having a more uniform thickness and a higher gloss than the conventional brightener was obtained from the high current density portion to the low current density portion. Example 5 1 mol of urea, 2 mol of diethylaminopropylamine, 0.7 mol of dichloroethyl ether and 0.3 mol of epibromohydrin were reacted at a temperature of 140 ° C. for 5 hours to obtain a water-soluble compound having a molecular weight of about 35,000. A reaction product was obtained (brightener E). 4 g / L of this brightener E, 10 g / L of Zn, N
aOH 150 g / L, Ni 1.5 g / L, reaction product of alkylamine and epihalohydrin 20 g / L, 1-ethanol-
0.5 g / L of peridinium 3-carboxylate, 30 g of No. 3 silicon /
A plating bath containing L and the balance being water (PH14 or higher)
In addition, iron plate as cathode, zinc plate as anode, total current 2A,
A Hull cell test was performed at a temperature of 25 ° C. for 20 minutes. As a result, a zinc plating film having a more uniform thickness and a higher gloss than the conventional brightener was obtained from the high current density portion to the low current density portion. Comparative Example 1 Zn 10 g as a plating bath using a conventional brightener
/ L, NaOH 150 g / L, 0.5 g / L of a reaction product of imidazole and epichlorohydrin, 1 g of a reaction product of dimethylamine and epichlorohydrin. Anode, total current 2
A, Hull cell test was performed at a temperature of 25 ° C. for 20 minutes.
As a result, a zinc plating film having a very thin film thickness was obtained in the low current density portion while the plating film thickness was large in the high current density portion. Comparative Example 2 As a plating bath using a conventional brightener, Zn 10 g was used.
/ L, NaOH 150 g / L, Ni 1.5 g / L,
Reaction product of diethylenetriamine and epichlorohydrin 2
0 g / L, 0.5 g / L of a reaction product of imidazole and epichlorohydrin and 1 g of a reaction product of dimethylamine and epichlorohydrin, an iron plate as a cathode, a zinc plate as an anode, A Hull cell test was performed at a total current of 2 A and a temperature of 25 ° C. for 20 minutes. As a result, the thickness of the high current density portion was larger than that of Example 5, and the zinc plating film of the low current density portion was extremely thin as compared with Example 5. The results are summarized in Table 1.

Table 1 Table 1 Relationship between distance (cm) from high current portion of Hull cell test panel and film thickness (μm) Distance (cm) 13 5 7 9 Example 1 7.4 6.9 6.4 6. 1 5.6 μm Example 2 6.3 6.1 5.8 5.4 4.8 Example 3 5.4 5.1 4.7 4.2 3.7 3.7 Example 4 5.6 5.4 5 5.2 4.9 4.5 Example 5 8.3 7.6 6.3 5.5 5.5 Comparative Example 1 15.7 10.4 7.9 3.9 1.4 Comparative Example 2 14.2 9.6 6.3 3.5 1.7

Claims (7)

[Claims] 1. An alkaline solution comprising (a) urea or thiourea, (b) a dialkylaminoalkylamine, and (c) a water-soluble reactive product of dichloroalkyl ether and (d) epihalohydrin. Zinc and zinc alloy plating bath. 2. The plating bath according to claim 1, which contains 0.1 to 50 g / L of a water-soluble reactant. 3. The plating bath according to claim 1, comprising 1 to 30 g / L of zinc and 60 to 200 g / L of alkali hydroxide. 4. The plating bath according to claim 1, which contains 1 to 100 g / L of colloidal silica or alkali silicate. 5. The metal ion is 30 to 1000 m of iron.
g / L, nickel 0.02-5 g / L, cobalt 0.0
The plating bath according to any one of claims 1 to 4, wherein the plating bath contains one or more of 2 to 5 g / L and 0.02 to 40 g / L of manganese. 6. A plating method for zinc or a zinc alloy, wherein the plating bath according to claim 1 is used. 7. Alkaline zinc containing (a) urea or thiourea, (b) a dialkylaminoalkylamine, and (c) a water-soluble reaction product of dichloroalkyl ether and (d) epihalohydrin. And brightener for zinc alloy plating bath.