JP4447100B2 - Alkaline zinc and zinc alloy plating bath - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a plating bath for electrodepositing shiny zinc or zinc alloy on various substrates, a brightener for use in the plating bath, and a plating method using the plating bath.
[Prior art]
While environmental measures in recent years have been screamed, the mainstay of zinc plating has shifted from plating baths using sodium blue soda to zincate baths using caustic soda that can be easily discharged, and technological development related to this has also progressed. is doing. In the zincate bath, the properties of the plating film depend greatly on the brightener, so the uniformity of the plating film has not been improved with the existing brightener. As a method for solving this problem, JP-A-8-209379 and JP-A-11-193486 propose a plating bath containing a reaction product of dialkylaminopropylamine, urea and dichloroalkyl ether as a main luster component. However, the plating bath using the reaction product has a problem that the uniformity of the film thickness at a high current density is good, but the plating speed does not increase even if the current density is increased.
[0002]
[Problems to be solved by the invention]
An object of the present invention is to provide an alkaline zinc and zinc alloy plating bath which is excellent in plating appearance and plating uniformity and has a high speed.
An object of the present invention is to provide a brightener for alkaline zinc and zinc alloy plating baths that is excellent in plating appearance and plating uniformity and has a high speed.
Another object of the present invention is to provide an efficient plating method using the above plating bath.
[Means for Solving the Problems]
The present invention provides a water-soluble reactive product of (a) urea or thiourea, (b) dialkylaminoethylamine and / or dialkylaminopropylamine and (c) dichloroalkyl ether for brightening for alkaline zinc and zinc alloy plating baths. It was made based on the knowledge that when used as an agent, the above problems could be solved efficiently.
That is, the present invention comprises a water-soluble reactive product of (a) urea or thiourea, (b) dialkylaminoethylamine and / or dialkylaminopropylamine and (c) dichloroalkyl ether. An alkaline zinc and zinc alloy plating bath is provided.
The present invention also provides a brightener for alkaline zinc and zinc alloy plating baths 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.
[0003]
DETAILED DESCRIPTION OF THE INVENTION
The reactive product obtained by reacting (a) urea or thiourea, (b) dialkylaminoethylamine and / or dialkylaminopropylamine and (c) dichloroalkyl ether used as a brightener in the present invention is, for example, It can be obtained by the following method.
(A) 1 mol of urea or thiourea, (b) 2 mol of dialkylaminoethylamine and / or dialkylaminopropylamine, and (c) 0.5 to 1 mol of dichloroalkyl ether, water-soluble reaction The reaction is preferably carried out at a temperature of 90 to 170 ° C. for 1 to 10 hours so that a product is obtained. The obtained reaction product preferably has a molecular weight of about 3,000 to 100,000, more preferably about 10,000 to 50,000.
(B) As dialkylaminoethylamine and / or dialkylaminopropylamine, it is preferable that carbon number of each alkyl group is 1-6, More preferably, it is 1-3. Specifically, dimethylaminoethylamine, diethylaminoethylamine, dipropylaminoethylamine, dibutylaminoethylamine, dimethylaminopropylamine, diethylaminopropylamine, dipropylaminopropylamine, or a mixture of two or more of dibutylaminopropylamine preferable. (B) is preferably a dialkylaminoethylamine alone or a mixture of dialkylaminoethylamine and dialkylaminopropylamine. In the case of mixed use, it is preferable to use 50 mol% or more of dialkylaminoethylamine.
[0004]
(C) As dichloroalkyl ether, it is preferable that carbon number of an alkyl group is 1-6, More preferably, it is 1-3. Specifically, one kind or a mixture of two or more kinds of dichloroethyl ether, dichloropropyl ether, dichlorobutyl ether are preferable.
As the water-soluble reactant, (a) and (b) are reacted and (c) is preferably reacted therewith, but (a), (b) and (c) are reacted in the same manner. May be.
In this invention, it is preferable to contain 0.1-50 g / L of the said water-soluble reaction product in a plating bath, More preferably, it is 0.5-20 g / L.
The alkaline zinc and zinc alloy plating bath of the present invention preferably contains 1 to 30 g / L in a dissolved zinc form, more preferably 5 to 20 g / L. It is preferable to contain 60-200 g / L of alkali metal hydroxide, for example, sodium hydroxide, more preferably 90-150 g / L.
[0005]
The alkaline zinc and zinc alloy plating bath of the present invention preferably has a pH of 13 or more, more preferably PH14 or more.
Various additives can be contained in the alkaline zinc and zinc alloy plating bath of the present invention.
For example, it is preferable to contain 1-100 g / L of alkali silicates such as colloidal silica and No. 3 silicon as silicate, and more preferably 5-50 g / L.
In the present invention, examples of the zinc alloy include alloys 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 alloy to be obtained and the alloy ratio thereof. For example, for zinc 5 to 20 g / L, iron It is good to add 1 type, or 2 or more types, such as 30-1000 mg / L, nickel 0.02-5 g / L, cobalt 0.02-5 g / L, manganese 0.02-40 g / L. Metal ions are preferably supplied in the form of chlorides or sulfates.
A chelating agent is preferably used to dissolve the metal salt. Examples of chelating agents include hydroxycarboxylic acids such as citric acid, tartaric acid, gluconic acid and glycolic acid and salts thereof, amino alcohols such as monoethanolamine, diethanolamine and triethanolamine, ethylenediamine, diethylenetriamine, triethylenetetramine and tetraethylene. Reactions of polyamines such as pentamine, polyimines, polyamines and epihalohydrins (ethylene chlorohydrin, epichlorohydrin, epibromohydrin) or halogen ethers (dichloroethyl ether, dichloropropyl ether, dichlorobutyl ether) It is preferable to use it. 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.
[0006]
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. Examples thereof include aldehydes such as vanillin, benzaldehyde, hydroxybenzaldehyde, ethyl vanillin, veratraldehyde, anisaldehyde, and a reaction product of nicotinic acid with halogenated hydrocarbon, alkylene oxide, epihalohydrin, halogen ether, and the like.
In the present invention, a substrate to be plated (iron, copper, brass or the like) is used as a cathode, a zinc plate or nickel or the like is used as an anode, and the plating bath is used, for example, a current density of 0.01 to 20 A / dm ² , a temperature. A plating method including a step of plating usually for 5 to 80 minutes (for example, a plating film thickness of 3 to 20 μm) until a predetermined plating thickness is obtained at 15 to 50 ° C. is also provided.
【The invention's effect】
According to the present invention, a zinc and zinc alloy plating film excellent in uniformity and film physical properties can be obtained at a higher plating rate than a brightener used in a conventional alkaline zinc and zinc alloy plating bath. In addition, when the chromate treatment is performed, the color tone of the processed product becomes brighter. This tendency is particularly noticeable in the UNIQLO system.
Next, the present invention will be described using examples.
[0007]
【Example】
Example 1
1 mol of urea, 2 mol of dimethylaminoethylamine and 1 mol of dichloroethyl ether were reacted at a temperature of 140 ° C. for 5 hours to obtain a water-soluble reaction product having a molecular weight of about 30,000 (brightener A).
This brightener A contains 0.5 g / L, Zn 10 g / L, and NaOH 120 g / L, and the balance is water. The plating bath (PH14 or more), the iron plate as the cathode, the zinc plate as the anode, A Hull Cell test was performed at 2A and a temperature of 25 ° C. for 20 minutes. As a result, a galvanized film having a high current density portion equivalent to that of the conventional brightener and a low current density portion having a thickness greater than that of the conventional brightener was obtained.
After the plating, a colorless chromate treatment was performed under the following conditions. As a result, a bright chromate film was obtained.
Chromate treatment process:
Plating → Washing → Activation treatment (67% nitric acid 8 ml / l, room temperature, 15 seconds) → Water washing → chromate treatment (trade name: Dipsol Z-400: 10 ml / l + 67% nitric acid: 15 ml / l, 25 ° C., 10 seconds )
[0008]
Example 2
In a plating bath (PH14 or more) containing 0.5 g / L of brightener A, 10 g / L of Zn, 120 g / L of NaOH, 0.005 g / L of 1-propyl-pyridinium 3-carboxylate, and the balance being water, The hull cell test was performed for 20 minutes at a total current of 2 A and a temperature of 25 ° C. with the iron plate as the cathode and the zinc plate as the anode. As a result, a galvanized film having a high current density portion equivalent to that of the conventional brightener and a low current density portion having a thickness greater than that of the conventional brightener was obtained.
Example 3
1 mol of urea and 2 mol of dimethylaminoethylamine were reacted at a temperature of 120 ° C. for 4 hours to obtain a reaction product having a molecular weight of about 200 (reaction product 1).
1 mol of urea and 2 mol of dimethylaminopropylamine were reacted at a temperature of 140 ° C. for 5 hours to obtain a reaction product having a molecular weight of about 250 (reaction product 2).
A mixture of 1 mol of reactant 1 and 2 mol of reactant 2 was reacted with 2 mol of dichloropropyl ether at a temperature of 140 ° C. for 5 hours to obtain a water-soluble reaction product having a molecular weight of about 30,000 (glossy). Agent B).
This brightener B contains 2 g / L, Zn 10 g / L, and NaOH 120 g / L, the balance being water is a plating bath (PH14 or more), the iron plate is used as a cathode, the zinc plate is used as an anode, and the total current is 2A. The hull cell test was performed at a temperature of 25 ° C. for 20 minutes. As a result, a galvanized film having a high current density portion equivalent to that of the conventional brightener and a low current density portion having a thickness greater than that of the conventional brightener was obtained.
[0009]
Example 4
A mixture of 1.5 mol of the reactant 1 obtained in Example 3 and 0.5 mol of the reactant 2 was reacted with 2 mol of dichloropropyl ether at a temperature of 140 ° C. for 5 hours to obtain a molecular weight of about 30,000. A water-soluble reaction product was obtained (brightener C).
In a plating bath (PH14 or higher) containing 4 g / L of this brightener C, 10 g / L of Zn, 150 g / L of NaOH, 0.5 g / L of 1-ethanol-pyridinium 3-carboxylate, and the balance being water, The hull cell test was performed for 20 minutes at a total current of 2 A and a temperature of 25 ° C. with the iron plate as the cathode and the zinc plate as the anode. As a result, a galvanized film having a high current density portion equivalent to that of the conventional brightener and a low current density portion having a thickness greater than that of the conventional brightener was obtained. Example 5
1 mol of urea, 2 mol of diethylaminoethylamine and 1 mol of dichloroethyl ether were reacted at a temperature of 140 ° C. for 5 hours to obtain a water-soluble reaction product having a molecular weight of about 35,000 (brightener D).
4 g / L of this brightener D, 10 g / L of Zn, 150 g / L of NaOH, 1.5 g / L of Ni, 20 g / L of a reaction product of diethylenetriamine and epichlorohydrin, 1-ethanol-pyridinium 3-carboxylate A hull cell test was performed at a total current of 2 A and a temperature of 25 ° C. for 20 minutes in a plating bath (PH14 or more) containing 5 g / L, the balance being water, an iron plate as a cathode and a zinc plate as an anode. As a result, a galvanized film having a high current density portion equivalent to that of the conventional brightener and a low current density portion having a thickness greater than that of the conventional brightener was obtained.
[0010]
Comparative Example 1
As a plating bath using a conventional brightener, Zn 10 g / L, NaOH 150 g / L, a reaction product of imidazole and epichlorohydrin 0.5 g / L, a reaction product of dimethylamine and epichlorohydrin 1 g The plating solution contained was an iron plate as a cathode and a zinc plate as an anode, and a hull cell test was performed at a total current amount of 2 A and a temperature of 25 ° C. for 20 minutes. As a result, the high current density part had a thick plating film thickness, but the low current density part had an extremely thin zinc plating film.
Further, after the plating, a colorless chromate treatment was performed under the same conditions as in Example 1. As a result, a chromate film having a slightly dark color tone was obtained.
Comparative Example 2
As a plating bath using a conventional brightener, Zn 10 g / L, NaOH 150 g / L, Ni 1.5 g / L, a reaction product of diethylenetriamine and epichlorohydrin 20 g / L, a reaction product of imidazole and epihalohydrin 0. A plating solution containing 5 g / L and 1 g of a reaction product of dimethylamine and epichlorohydrin, an iron plate as a cathode, a zinc plate as an anode, and a hull cell test at a total current of 2 A and a temperature of 25 ° C. for 20 minutes. . As a result, the high current density part had a film thickness almost equivalent to that of Example 5, and the low current density part had a galvanized film having an extremely thin film thickness as compared with Example 5.
[0011]
The results are summarized in Table 1.
[Table 1]
Table 1 Relationship between distance (cm) and film thickness (μm) from high current portion of Hull cell test panel 1 3 5 7 9
Example 1 13.5 10.0 8.0 5.7 5.0 μm
Example 2 13.6 10.9 9.0 7.0 5.1
Example 3 11.8 9.3 7.6 6.5 4.7
Example 4 10.8 8.5 7.1 5.9 4.4
Example 5 13.7 9.4 6.8 4.2 3.4
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)

Alkaline zinc characterized by containing (a) urea or thiourea, (b) dialkylaminoethylamine , or dialkylaminoethylamine and dialkylaminopropylamine , and (c) a water-soluble reactive product of dichloroalkyl ether And zinc alloy plating bath.   The plating bath according to claim 1, comprising 0.1 to 50 g / L of a water-soluble reactant.   The plating bath of Claim 1 or 2 containing 1-30 g / L of zinc and 60-200 g / L of alkali hydroxide.   The plating bath according to any one of claims 1 to 3, comprising 1 to 100 g / L of colloidal silica or alkali silicate.   The metal ion contains at least one of iron 30 to 1,000 mg / L, nickel 0.02 to 5 g / L, cobalt 0.02 to 5 g / L, and manganese 0.02 to 40 g / L. The plating bath according to any one of the above.   A method for plating zinc or a zinc alloy, wherein the plating bath according to any one of claims 1 to 5 is used. alkaline zinc, characterized in that it contains (a) urea or thiourea, (b) dialkylaminoethylamine , or dialkylaminoethylamine and dialkylaminopropylamine , and (c) a water-soluble reaction product of dichloroalkyl ether, and Brightener for zinc alloy plating bath.