JPH11193488A - Alkaline plating bath for zinc or zinc alloy and plating process - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain good external appearance, excellent uniform adhesion and covering power, good chromating property, etc., by incorporating >=1 kind of polymer selected from a group consisting of the polymers of specified structure into the plating bath. SOLUTION: The polymer selected from the polymers shown by formulas I, II, III TV, V, VI and VII and the polymers of the monomers expressed by formulas VIII and IX is incorporated into the plating bath for zinc or zinc alloy contg. zinc, conductive salt and silicon compd. and further contg. metals constituting an alloy in the case of alloy plating. In all the formulas, R1, R2, R3 and R4 are H, 1-5C alkyls, etc., R5 is (CH2 )2 -O-(CH1 )1 , etc., X is 0 to 5, Y is S or O, and (n) is an integer of >=1. X is inorg. ion in formulas VI and VII. The plating bath contains an appropriate amt. of aldehyde, the conductive salt is NaOH, and the bath appropriately contains 3-80 g/L zinc, 30-250 g/L NaOH, 0.01-200 g/L silicon compd. and 0.1-50 g/L bath-soluble polymer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for applying zinc or a zinc alloy and a plating thereof to a metal material, and more particularly to a technique for improving zinc and zinc-based alloy plating properties by using a silicon compound and a bath-soluble polymer. It is.

[0002]

2. Description of the Related Art Generally, zinc or zinc-based alloy plating (hereinafter referred to as "zinc plating") is used as a method for preventing rust on iron-based materials and parts.
Is the most widely used. Zinc plating baths are broadly divided into acid baths and alkaline baths. Overall (in a wide current density range) gloss, pit prevention, excellent covering properties, excellent leveling properties, high zinc concentration to increase efficiency Many studies have been conducted for a long time, such as the possibility of use in steels, good chromate treatment, and the uniform alloy ratio over a wide current density range in alloy plating. Alkaline zinc plating is composed of zinc and a conductive salt such as sodium hydroxide. However, if used without a brightener, an additive or a chelating agent, it becomes a coarse sponge-like precipitate and is not practical.

Alkali baths containing cyan have been used for a long time, but alkali plating baths that do not use cyan have been invented more than 20 years ago and are now in view of cyan toxicity and environmental considerations. In other words, plating baths that do not use cyanide (hereinafter referred to as zincate baths) are sponge-like deposition-suppressed by a specific additive such as a reaction product of amine and epihalohydrin and polyethylene polyamine, and have been improved in many ways so as to obtain excellent gloss. Has been. However, the performance required for the brightener (performance required for plating) is not limited to the fact that a strong gloss can be obtained. Not only is the beauty of appearance (glossiness) obtained not only in the specific current density area, but also in a wide current density range, but also corrosion resistance, cracking, leveling, excellent throwing power,
Many performances are required, such as a wide range of conditions such as pit prevention, chromate treatment, coating adhesion, and zinc concentration. In the case of alloy plating, a uniform alloy ratio in a wide current density range is further required.

In recent years, much research has been devoted to improving corrosion resistance in order to cope with a severely corrosive environment caused by snow-melting salt, and zinc-iron, zinc-nickel, zinc-iron-cobalt and the like having higher corrosion resistance are plated. The development of alloy plating is eager. These alloy platings consist of a chelating agent of an amine or an organic acid in a zincate bath, a metal as an alloying component, and a specific additive (brightening agent).
Although alloy plating has contributed to a significant improvement in the property of corrosion resistance, it involves new problems in terms of the environmental problem, which was the original purpose of zincate baths. That is, the alloy plating solution contains a chelating agent comprising sodium gluconate and various amines. As the name implies, chelating agents chelate metals, making it difficult to remove heavy metals from industrial wastewater containing them.Thus, great care must be taken to clear today's strict emission regulations. is there. In addition, even if these chelating agents do not chelate metals, they are subject to emission regulations (COD, BOD).

[0005] As described above, zinc plating has developed a zincate bath in order to respond to environmental problems and has been improving additives corresponding to the market. However, with the advent of alloy plating, characteristics other than corrosion resistance have been almost the same as those of more than 10 years ago. The performance remains the same, and alloy plating has a new environmental problem. U.S. Pat. Nos. 3,853,718, 3,869,358, 38, which describe improved galvanizing baths containing certain brighteners.
84774, 4111383, 4169771, 422
9267, 4730022, 4792038, 5182
A number of patents have been filed, including 006, 5194410.

[0006]

SUMMARY OF THE INVENTION The object of the present invention is to provide a good appearance (overall (in a wide current density range) gloss, pit prevention, leveling properties, etc.) of the characteristics required in electroplating, and excellent uniformity. Electrodeposition properties, cracking properties, use at high zinc concentration to improve efficiency or use at high bath temperature, good chromate treatment, uniform alloy ratio over a wide current density range in alloy plating, high corrosion resistance Another object of the present invention is to provide a plating bath having good wastewater treatment properties.

[0007]

As a result of diligent studies conducted by the present inventors, the problem in the prior art is that zinc, a conductive salt and a silicon compound are contained, and in the case of alloy plating, a metal which is an alloy component is contained. In a zinc or zinc alloy plating bath, the structural formula (1) is used as a bath-soluble polymer.

Embedded image (Wherein R 1 and R 2 are hydrogen, methyl, ethyl, isopropyl, butyl, —CH ₂ CH ₂ (OCH ₂ CH ₂ ) _X O
H (X is 0-5) or -CH ₂ CH ₂ (OCCH ₂ CH
_{2) X} OH (X represents 0-5), polymer n is represented by representing one or more), the structural formula (2)

Embedded image (Wherein, R1, R2, each hydrogen R3 and R4, methyl, ethyl, isopropyl, 2-hydroxyethyl _{-CH 2 CH 2 (OCH 2 CH} 2) x OH (X 0~
6) or 2-hydroxylethyl-CH ₂ CH ₂ (OC
_{CH 2 CH 2) x OH (} X represents Less than six), R5 is _{(CH 2) 2 -O- (CH} 2) 2, (CH 2) 2 -O-
_{(CH 2) 2 -O- (CH} 2) 2 or CH ₂ -CHOH
It represents _{-CH 2 -O-CH 2 -CHOH-} CH 2, n
Is 1 or more, and Y is S or O), a polymer represented by the structural formula (3):

Embedded image (Wherein, R1, R2, each hydrogen R3 and R4, methyl, ethyl, isopropyl, 2-hydroxyethyl _{-CH 2 CH 2 (OCH 2 CH} 2) x OH (X 0~
6) or 2-hydroxylethyl-CH ₂ CH ₂ (OC
_{CH 2 CH 2) x OH (} X represents Less than six), R5 is _{(CH 2) 2 -O- (CH} 2) 2, (CH 2) 2 -O-
_{(CH 2) 2 -O- (CH} 2) 2 or CH ₂ -CHOH
It represents _{-CH 2 -O-CH 2 -CHOH-} CH 2, n
Represents one or more, and Y represents S or O), a polymer represented by the structural formula (4):

[0008]

Embedded image (Wherein each hydrogen R1 and R2, methyl, ethyl, isopropyl, butyl, -CH ₂ CH ₂ (OCH ₂
CH ₂ ) _X OH (X is 0 to 5) or —CH ₂ CH ₂ (O
(CCH ₂ CH ₂ ) _X OH (X represents 0 to 5), n represents 1 or more, and Y represents O or S) as a monomer, a structural formula (5)

Embedded image (Wherein R1 or R2 represents hydrogen, methyl, ethyl, butyl or isobutyl, and R3 is CH ₂ , C ₂ H ₄ or C
₃ H ₆ ), structural formula (6)

Embedded image (Wherein R1 and R2 each represent hydrogen or carbon atoms of 10
A polymer represented by the following alkyl), structural formula (7)

Embedded image (Wherein, R1, R2, R3 and R4 each represent hydrogen or an alkyl having C of 5 or less, X represents an inorganic anion, Y represents S or O), and a structural formula ( 8)

Embedded image Wherein R 1, R 2, R 3 and R 4 each represent hydrogen or alkyl having 5 or less carbon atoms, X represents an inorganic anion, and Y represents S or O. It has been found that the solution is achieved by a plating bath for zinc or zinc alloy containing one or more selected.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION As a preferable polymer of the structural formula (1) based on the results of the effects, "MIRAPOL (trademark) 100" commercially available from Rhone Poulin, and an example of the polymer of the structural formula (2) is MIRAPOL
(Trademark) WT ", examples of the polymer of the structural formula (3) include" MIrapol (trademark) AD-1 ", and examples of the polymer of the structural formula (4) include" MIrapol (trademark) 550 ". . The total amount of these bath-soluble polymers in the plating bath is preferably from 0.1 to 50 g / L. As described in JP-A-8-209393, as a silicon compound, colloidal silica, a powdery substance which becomes colloidal silica when dispersed in water, a silicate (general formula mMOx.nSiO2: M is a metal m, n is a natural number,
x can be almost any silicon compound such as 1 or 2),
For example, No. 3 sodium silicate can be used.

[0010] Zinc is 3-80 g / L, preferably 5-20
g / L, 30 to 250 g / L of sodium hydroxide, preferably 0.01 to 2 g of 90 to 150 g / L silicon compound.
00 g / L, preferably 1 to 150 g / L, structural formula (1) to
The polymer of (8) is 0.1 to 50 g / L, preferably 1 to 50 g / L.
Vanillin, benzaldehyde, ethyl vanillin, veratraldehyde, and anisaldehyde give relatively good gloss as aldehydes.
001 to 50 g / L, preferably 10 to 5000 mg / L
The existing plating bath provides a good plating film.
Each amount is different depending on whether zinc plating or alloy plating,
Also in the alloy plating, since an appropriate eutectoid ratio differs depending on the alloy components, the amounts of the components are different from each other and cannot be determined unconditionally. For example, in the case of zinc plating, zinc is 5 to 25 g /
L and sodium hydroxide 90 to 150 g / L are generally in the range where a good film can be obtained.

As the metal to be alloyed, iron, cobalt, nickel, trivalent chromium or copper is suitable. In addition, zinc
In the case of iron alloy plating, zinc 6 to 20 g / L, iron 0.00
1 to 1.0 g / L, sodium hydroxide 85 to 150 g /
L is a general range for obtaining a uniform film. In any case, it cannot be determined unconditionally because it is affected by conditions such as current density and bath temperature. There is no limitation on the method of supplying the alloy component, and the alloy component can be supplied with a salt such as iron sulfate, iron chloride, and cobalt sulfate.

The functions of the respective components in the plating solution are as follows. Zinc and the metal as the alloy component are preferably precipitated metals, and the essential conductive salt is preferably sodium hydroxide. By adding the polymers of the structural formulas (1) to (8), the basic properties required for galvanizing, such as uniform gloss, leveling, uniform electrodeposition, and peeling resistance, are improved. Although it is unlikely that the silicon compound chelates the alloy component, the added plating bath is stable even when a chelating agent that adversely affects wastewater treatment such as sodium gluconate is not added, and the added metal is stable in the bath and a uniform ratio is obtained. This makes it possible to perform precipitation. In addition, with conventional plating solutions containing a chelating agent, the color tone of the solution is estimated to deteriorate or degrade due to high temperature work or prolonged use, and the plating appearance is degraded (the appearance of matte black appearance is poor). However, it was necessary to use a great deal of know-how and pay close attention to use in a narrow range of plating conditions. In the invention, these defects are not confirmed.

Further, the present invention is characterized in that when alloy plating is performed, the amount of addition of a metal as an alloy component can be reduced. Many alloy plating patents claim the amount of metal to be added as an alloy component is infinitely claimed from a value close to 0, but the total amount of metal in alloy plating currently in practical use is approximately 100 to 100%. 2000 mg / L or more. On the other hand, according to the present invention, an addition amount that is one digit smaller (for example, about 10 mg / L of iron) is possible. Further, the conventional plating bath is weak against temperature, and plating under a condition exceeding 30 ° C. is not a material that can be industrially used. However, the plating bath of the present invention has excellent temperature resistance and a plating condition exceeding 30 ° C. But it is enough for practical use.

In general, it is known that, in zinc plating, if a chelating agent is not contained, metals other than zinc are impure metals and adversely affect the appearance and physical properties of the film. For example, META
As described in LFINITISHING, February 1995, a low metal content of 0.1 mg / L and iron and nickel content of 1 to 10 mg / L have an adverse effect. -10mg / L
Even if mixed, it becomes an alloy plating and the corrosion resistance may be improved, but no deterioration in appearance or the like is recognized. This is one of the ways in which the present invention can be easily managed when considered as a mere zinc plating instead of an alloy plating. In addition, most of the alloy plating patents use an organic acid such as amine or sodium gluconate as a chelating agent, and they all seem to be the same, but the chelating agents that have been put into practical use have high target metal selectivity. Even if the chelating agent used in zinc-iron alloy plating is added to the zinc-nickel bath, good plating cannot be obtained. Therefore, a good result may be obtained for a specific metal only by adding the conventional chelating agent to the galvanization, but the management shown in the present invention in an industrial line where various kinds of metals are considered to be mixed. Ease is not obtained.

In addition to these, the present invention also improves other characteristics of conventional galvanizing. For example, the peeling resistance is often overlooked because it is not directly visible compared to the gloss of the appearance, but it is an important performance that cannot be ignored when evaluating zinc plating. The cracking ability is an ability to obtain an effective plating even in a lower current density region. Industrial plating is for plating a member having a much more complicated shape than the beaker level, so that the current density on the surface of the member is a very wide current density. For example, 0.1
When processing a member with a current density range of 〜１０10 A / dm ²

[0016]

[Table 1]

When a film thickness distribution of
In the range of A / dm ^2, the uniformity of electrodeposition is relatively excellent and good, but when it is less than 0.5 A / dm ² , the film thickness is suddenly reduced and the cracking property is poor. The present invention solves the problems of conventional galvanization, such as pit prevention and chromate treatment, as well as these capabilities.

The plating bath of the present invention can contain a known substance that can be added to electrogalvanizing. As these additives, for example, amine-based gloss-imparting agents, leveling agents, P
VA, gelatin, glue, peptone and the like.
Specifically, polyethyleneimine, reactant of amine and epihalohydrin, reactant of alcohol and amine, allyl sulfonate, propyne sulfonate, pinyl sulfonate, aminopropine derivative, bisbenzenesulfonylimide, benzylpyridinium There are carboxylate, hexinediol, propargyl alcohol and the like, and the addition amount is a standard of 0.01 to 50 g / L.

[0019]

The present invention will be described below with reference to examples. The test used a Hull cell test plate, a 50 × 100 × 1 mm iron plate or bolt as a test piece. After performing appropriate pretreatments (such as degreasing and desmutting), the following treatments were performed. Example 1 Zinc 11 g / L, sodium hydroxide 125 g / L, No. 3 sodium silicate 85 g / L, "MIRAPOL 100"
The Hull cell test was performed in a plating bath containing 2.5 g / L and vanillin 50 mg / L. A test piece electrolyzed with 2A for 15 minutes was immersed in green chromate mainly composed of chromic acid and phosphoric acid, and subjected to chromate treatment as passivation treatment. Good uniform and glossy plating was obtained.

Example 2 13 g / L of zinc, 130 g / L of sodium hydroxide, 90 g / L of sodium silicate No. 3, 2 g of "MIRAPOLWT"
/ L and a plating bath containing anisaldehyde 55 mg / L were subjected to a Hull cell test. A test piece electrolyzed with 2A for 15 minutes was immersed in green chromate containing chromic acid and phosphoric acid as main components, and subjected to chromate treatment. Good uniform and glossy plating was obtained. “MIRAPOL WT” to “MIR
"APOL550" or "MIRPOL AD-1"
Similarly, a good result was obtained even if it was changed to. Example 3 10.5 g / L zinc, 110 g / L sodium hydroxide,
The Hull cell test was performed in a plating bath containing 95 g / L of No. 3 sodium silicate, 2 g / L of the polymer represented by the structural formula (5), and 65 mg / L of veratraldehyde. A test piece electrolyzed with 2A for 15 minutes was immersed in green chromate containing chromic acid and phosphoric acid as main components, and subjected to chromate treatment. Good uniform and glossy plating was obtained.

Example 4 8.5 g / L of zinc, 100 g / L of sodium hydroxide, 75 g / L of sodium silicate No. 3, polymer 3 of structural formula (8)
A Hull cell test was performed in a plating bath containing g / L and 65 mg / L of vanillin. The test piece electrolyzed with 2A for 15 minutes was immersed in green chromate containing chromic acid and phosphoric acid as main components to perform chromate treatment. Good uniform and glossy plating was obtained. Similarly good results were obtained when the polymer of structural formula (8) was replaced with the polymer of structural formula (6) or the polymer of structural formula (7). Example 5 8 g / L of zinc, 110 g / L of sodium hydroxide, 80 g / L of sodium silicate No. 3, "MIRAPOL 550" 2
The Hull cell test was performed in a plating bath containing g / L, 2.5 g / L of the polymer of the structural formula (6), and 45 mg / L of vanillin. A test piece electrolyzed with 2A for 15 minutes was immersed in green chromate containing chromic acid and phosphoric acid as main components, and subjected to chromate treatment. Good uniform and glossy plating was obtained.

Example 6 8 g / L of zinc oxide, 110 g / L of sodium hydroxide and 3 g / L of "MIRAPOLAD-1", 3 g / L of the polymer of the structural formula (7), 90 g of sodium silicate 3
L, benzylpyridinium carboxylate 4 g / L,
A Hull cell test was performed in a plating bath containing 0.05 g / L of ethyl vanillin. Table 1 shows the results obtained by measuring the film thickness of a portion corresponding to 0.1, 0.5, 1, ² , 3, 5, 10 A / dm ² of the test piece subjected to 2A-20 minutes electrolysis using a film thickness meter. General additives (imidazole-epihalohydrin.
(Copolymer + polyamide), it was confirmed that the uniform electrodeposition property and the peeling property were excellent.

[0023]

[Table 2]

EXAMPLE 7 10 g / L of zinc oxide, 120 g / L of sodium hydroxide and 3 g / L of "MIRAPOLWT", structural formula (6)
2 g / L of polymer, 100 g / L of No. 3 sodium silicate,
A Hull cell test was performed in a plating bath containing 0.05 g / L of vanillin. 2A-0.1 of test piece electrolyzed for 20 minutes,
When the film thicknesses of the portions corresponding to 0.5, 1, ^{2, 3, 5, and 10 A} / dm ² were measured with a film thickness meter, the results shown in Table 2 were obtained. It was confirmed that the uniform electrodeposition property and the exfoliation property were superior to those of a general additive (imidazole-epihalohydrin copolymer + polyamide + formalin).

[0025]

[Table 3]

Example 8 10 g / L of zinc oxide, 110 g / L of sodium hydroxide and 1 g / L of "MIRAPOL550", 2 g / L of a polymer represented by the structural formula (5), Cataloid SI-30 (manufactured by Catalyst Chemicals, Inc.) 150 g / L, urea derivative 0.5 g /
The Hull cell test was performed in a plating bath containing L and vanillin 40 mg / L. A test piece electrolyzed with 2A for 20 minutes was immersed in a green chromate mainly composed of chromic acid and phosphoric acid at room temperature to perform a chromate treatment. Specimens using a common additive (imidazole-epihalohydrin copolymer + polyamide) had a non-uniform color appearance, but the present invention had a uniform appearance. Example 9 9 g / L of zinc oxide, 120 g / L of sodium hydroxide and 10 g / L of "MIRAPOLWT", structural formula (5)
A Hull cell test was performed in a plating bath containing 2 g / L of polymer, 140 g / L of Cataloid SI-30 (manufactured by Catalysis Kasei Co., Ltd.), 3 g / L of benzylpyridinium carboxylate, and 20 mg / L of vanillin. A test piece electrolyzed with 2A for 20 minutes was immersed in a green chromate mainly composed of chromic acid and phosphoric acid at room temperature to perform a chromate treatment. General additives (imidazole-epihalohydrin copolymer +
Although the test piece using the polyamide) had a non-uniform color appearance, the present invention exhibited a uniform appearance.

Example 10 25 g / L of zinc oxide, 180 g / L of sodium hydroxide and 3 g / L of "MIRAPOLAD-1", 110 g / L of cataloid SI-30 (manufactured by Catalysis Kasei Co., Ltd.), structural formula (5) 3 g / L of urea derivative 1 g / L,
A Hull cell test was performed in a plating bath containing vanillin 60 mg / L. The appearance of the test piece electrolyzed for 2A-10 minutes was smooth and good. When a general additive (imidazole-epihalohydrin copolymer + polyamide) was used, a bad appearance called burn or kogation was exhibited in a high current density region. Example 11 8 g / L of zinc oxide, 110 g / L of sodium hydroxide and 3 g / L of "MIRAPOL100", Cataloid S
Hull cell test in a 40 ° C. plating bath containing 160 g / L of I-30 (manufactured by Catalyst Chemicals, Inc.), 3 g / L of polymer of structural formula (6), 0.2 g / L of urea, and 60 mg / L of anisaldehyde Was done. The appearance of the test piece electrolyzed for 2A-10 minutes was smooth and good. When a general additive (imidazole-epihalohydrin copolymer + polyamide) was used, a defect called burn or kogation and a pitted appearance were exhibited in a high current density region.

Example 12 10 g / L of zinc oxide, 120 g / L of sodium hydroxide and 3 g of "MIRAPOLWT", cataloid SI-
30 (manufactured by Catalyst Chemicals, Inc.) 100 g / L, structural formula (5)
2g / L of polymer, 1g of reaction product of alcohol and amine
/ L, a urea derivative 1 g / L, and a vanillin 50 mg / L were subjected to a Hull cell test in a plating bath. 2A-0.05, 0.1, 0.5, 1, 2,
The results shown in Table 3 were obtained by measuring the film thickness of the portions corresponding to 3, 5, and 10 A / dm ² with a film thickness meter. It was confirmed that the uniform electrodeposition property and the peeling resistance were superior to those of a general additive (imidazole-epihalohydrin copolymer + polyamide).

[0029]

[Table 4]

Example 13 40 g / L of zinc oxide, 160 g / L of sodium hydroxide and 4 g of "MIRAPOL550", 90 g / L of sodium silicate No. 3, 3 g / L of polymer of the structural formula (7), and 0.1 g of hexynediol. 5 g / L, urea derivative 0.5 g / L,
A Hull cell test was performed in a plating bath containing 60 mg / L of veratraldehyde. The appearance of the test piece electrolyzed for 2A-20 minutes was smooth and good. When a general additive (imidazole-epihalohydrin copolymer + polyamide) was used, a bad appearance called burn or kogation and a streak-like bad appearance with little gloss were exhibited in a high current density region. Example 14 25 g / L of zinc oxide, 180 g / L of sodium hydroxide and 3 g / L of “MIRAPOL 100”, “MIRA
POL WT "5g / L, No.3 sodium silicate 140g
/ L, benzylpyridinium carboxylate 1 g /
A Hull cell test was performed in a plating bath containing L and vanillin 60 mg / L. The appearance of the test piece electrolyzed for 2A-10 minutes was smooth and good. When a general additive (imidazole-epihalohydrin copolymer + polyamide) was used instead of the present invention, a bad appearance called burn or kogation was exhibited in a high current density region.

Example 15 10 g / L of zinc oxide, 150 g / L of sodium hydroxide and 2 g / L of "MIRAPOL550"
POL WT ”4 g / L, polymer 3 of structural formula (5)
The Hull cell test was performed in a plating bath containing g / L, No. 3 sodium silicate 120 g / L, polyethyleneimine 2 g / L, thiourea derivative 0.2 g / L, and veratraldehyde 40 mg / L. A test piece electrolyzed with 2A for 20 minutes was immersed in a green chromate mainly composed of chromic acid and phosphoric acid at room temperature to perform a chromate treatment. Specimens using a common additive (imidazole-epihalohydrin copolymer + polyamide) had a non-uniform color appearance and streak-like poor plating appearance, but the present invention exhibited a uniform appearance. Example 16 Zinc oxide 15 g / L, sodium hydroxide 140 g / L and No. 3 sodium silicate 90 g / L, "MIRAPOL
550 "is 4 g / L, and the polymer of the structural formula (8) is 2 g / L.
The Hull cell test was performed in a plating bath containing L, vanillin 50 mg / L, iron 10 mg / L, and nickel 10 mg / L. Chromic acid, phosphoric acid,
It was immersed in black chromate containing sulfuric acid and inorganic salts at room temperature to perform chromate treatment. A test piece using a general additive (imidazole-epihalohydrin copolymer + polyamide) exhibited an interference color and did not have a uniform black appearance.
In addition, in the test piece to which No. 3 sodium silicate was not added, the darkening of the low current density portion and the decrease in the adhesion of the plating film were confirmed, but the present invention exhibited a uniform appearance and the decrease in the adhesion was also recognized. Did not.

Example 17 18 g / L of zinc oxide, 140 g / L of sodium hydroxide and 150 g / L of sodium silicate No. 3, "MIRAPOL"
"550" 2g / L, "MIRAPOL WT" 4g
/ L, 3 g / L of the polymer of the structural formula (6), 1 g / L of benzylpyridinium carboxylate, and 40 mg / L of veratraldehyde were subjected to rotary plating. A test piece electrolyzed at a bath temperature of 38 ° C. at 12 A / kg for 20 minutes was immersed in a black chromate containing chromic acid, phosphoric acid, sulfuric acid, and an inorganic salt at room temperature to perform a chromate treatment. A test piece using a general additive (imidazole-epihalohydrin copolymer + polyamide) had a less glossy appearance and a plating film thickness in a low current portion was insufficient, so that a uniform black appearance was not obtained. A glossy uniform appeared. Example 18 10 g / L of zinc oxide, 110 g / L of sodium hydroxide and 120 g / L of sodium silicate No. 3, "MIRAPOL
100 "is 2g / L," MIRAPOL WT "is 4g
/ L, 3 g / L of polymer of structural formula (7), urea derivative 1
Rotational plating was performed in a plating bath containing g / L and 40 mg / L of veratraldehyde. A test piece electrolyzed at 12 A / kg for 25 minutes was immersed in a black chromate containing chromic acid, phosphoric acid, sulfuric acid, and an inorganic salt at room temperature to perform a chromate treatment. In the test piece using a general additive (imidazole-epihalohydrin copolymer + polyamide) instead of the present invention, the plating thickness in the low current portion was insufficient and a uniform black appearance was not obtained. Appeared.

Example 19 12 g / L of zinc oxide, 90 g / L of sodium hydroxide and 130 g / L of sodium silicate No. 3, "MIRAPOL"
WT ", 3 g of polymer of structural formula (8) 2 g / L, hexynediol 0.5 / L, vanillin 50 mg / L, iron 1
A Hull cell test was performed in a plating bath containing 5 mg / L and 35 mg / L of cobalt. A test piece electrolyzed with 3A for 15 minutes was immersed in a black chromate containing chromic acid, phosphoric acid, sulfuric acid, and an inorganic salt at room temperature to perform a chromate treatment. A test piece using a general additive (imidazole-epihalohydrin copolymer + polyamide) exhibited an interference color and did not have a uniform black appearance. In addition, in the test piece to which No. 3 sodium silicate was not added, darkening was observed in the low current density part and the adhesion of the plating film was reduced, but the present invention uniformly exhibited the appearance and the adhesion was also reduced. Did not.

Example 20 5 g / L of zinc oxide, 100 g / L of sodium hydroxide and 120 g of Cataloid SI-30 (manufactured by Catalysis Kasei Co., Ltd.)
/ L, 4 g / L of “MIRAPOL WT”, 1 g / L of urea derivative, 40 mg / L of ethyl vanillin, 80 mg of iron
/ L and 100 mg / L of cobalt were subjected to spin plating in a plating bath. A test piece electrolyzed at 8 A / kg for 35 minutes was immersed in a black chromate containing chromic acid, phosphoric acid, sulfuric acid, and an inorganic salt at room temperature to perform a chromate treatment. The test piece using a general additive (imidazole-epihalohydrin copolymer + polyamide) did not have a uniform black appearance due to insufficient plating film thickness in the low current density part. The plating without the addition of Cataroid SI-30 showed a non-uniform appearance presumably due to non-uniform eutectoid, but the present invention exhibited a uniform appearance. Example 21 17 g / L of zinc oxide, 140 g / L of sodium hydroxide and 150 g / L of sodium silicate No. 3, "MIRAPOL
"550" 2g / L, "MIRAPOL WT" 4g
/ L, 3 g / L of the polymer of the structural formula (7), 1 g / L of benzylpyridinium carboxylate, 40 mg / L of veratraldehyde, and 1200 mg / L of nickel were subjected to rotary plating. A test piece electrolyzed at 12 A / kg for 20 minutes was immersed in a black chromate containing chromic acid, phosphoric acid, sulfuric acid, and inorganic salt at room temperature to perform a chromate treatment. A test piece using a general additive (imidazole-epihalohydrin copolymer + polyamide) instead of MIRAPOL had a low gloss appearance and a low plating thickness in a low current portion, and a uniform black appearance was not obtained. The plating without the addition of No. 3 sodium silicate showed a non-uniform appearance presumably caused by non-uniform eutectoid, but the present invention exhibited a uniform appearance.

Example 22 9 g / L of zinc oxide, 110 g / L of sodium hydroxide and 130 g / L of sodium silicate No. 3, "MIRAPOL"
100 "is 15 g / L, and the polymer of the structural formula (8) is 1 g / L.
L, urea derivative 2 g / L, ethyl vanillin 40 mg /
A Hull cell test was performed in a plating bath containing L and nickel at 1 g / L. 2A-0.05 of test piece electrolyzed for 20 minutes,
Table 4 (film thickness) and Table 5 (eutectoid ratio) where the eutectoid ratio and the film thickness of nickel corresponding to 0.1, 0.5, 1, ² , 3, 5, 10 A / dm ² were measured. Was obtained. With a general additive (imidazole-epihalohydrin copolymer + polyamide) and Mirapol 100 alone, a plating bath that does not contain No. 3 sodium silicate does not provide even a good plating appearance, and some nickel becomes nickel hydroxide and becomes a solution. Floated without dissolving. For comparison, amine or sodium gluconate was added as a chelating agent to a general additive (imidazole-epihalohydrin copolymer + polyamide) and 15 g / L of “MIRAPOL100” plating solution.

[0036]

[Table 5]

[0037]

[Table 6]

Example 23 18 g / L of zinc oxide, 120 g / L of sodium hydroxide and 150 g / L of cataloid SI-30, "MIRA
POL WT ", 10 g / L, 2 g / L of polymer of structural formula (7), 1 g of benzylpyridinium carboxylate
/ L, 40 mg / L of vanillin, 35 mg / L of iron, and 20 mg / L of cobalt were subjected to a Hull cell test. 2A-20.
When the film thicknesses of the portions corresponding to 1, 0.5, 1, ^{2, 3, 5,} 10 A / dm ² were measured, the results shown in Table 6 (film thickness) were obtained. A general additive (imidazole-epihalohydrin copolymer + polyamide) and Mirapol WT alone cannot provide a good plating appearance even in a plating bath containing no No. 3 sodium silicate, and a general additive (imidazole-epihalohydrin copolymer + polyamide) Polyamide) and “MIR
An amine or sodium gluconate was added as a chelating agent to a 10 g / L plating solution of “APOL WT”.

[0039]

[Table 7]

Example 24 12 g / L of zinc oxide, 120 g / L of sodium hydroxide and 100 g / L of sodium silicate No. 3, "MIRAPOL"
100 "is 20 g / L, 1 g of the polymer of the structural formula (5)
/ L, urea derivative 3 g / L, ethyl vanillin 40 mg /
The bolt was spin-plated in a plating bath containing L and nickel at 1 g / L. Plating is 11A / kg, 35 minutes, 38 ° C
Was performed under the following conditions. Although a general additive (imidazole-epihalohydrin copolymer + polyamide) and Mirapol 100 alone could not provide a good plating appearance even in a plating bath containing no sodium silicate No. 3, the present invention provides not only plating appearance but also chromate treatment. And a uniform and good film was obtained. Example 25 15 g / L of zinc oxide, 120 g / L of sodium hydroxide and 130 g / L of sodium silicate No. 3, "MIRAPOL
WT "20g / L, iron 35mg / L, cobalt 15
The bolt was spin-plated in a plating bath containing mg / L. The plating was performed under the conditions of 10 A / kg, 35 minutes, and 38 ° C. General additives (imidazole-epihalohydrin copolymer + polyamide) and MIRAPOL W
Although a good plating appearance was not obtained even in a plating bath containing no No. 3 sodium silicate by T alone, in the present invention, a uniform and good coating was obtained not only in plating appearance but also in chromate treatment. Similar results were obtained after treating a 100 kg / L bolt.

Example 26 10 g / L of zinc oxide, 110 g / L of sodium hydroxide,
No.3 sodium silicate 120g / L, "MIRAPOL W
T "in a plating bath having a bath composition of 15 g / L,
L or nickel 20mg / L or copper 5mg / L
, And a good coating was obtained when plating was performed. Additive without adding No. 3 sodium silicate (PIRAP
A plating solution containing only OL WT or a general additive) resulted in poor plating such as a decrease in gloss at a low current density portion.

Claims (7)

[Claims] In a plating bath for zinc or a zinc alloy containing zinc, a conductive salt and a silicon compound, and further containing a metal to be an alloy component in the case of alloy plating, a structural formula (1) is used as a bath-soluble polymer. Formula 1 (Wherein R 1 and R 2 are hydrogen, methyl, ethyl, isopropyl, butyl, —CH ₂ CH ₂ (OCH ₂ CH ₂ ) _X O
H (X is 0-5) or -CH ₂ CH ₂ (OCCH ₂ CH
_{2) X} OH (X represents 0-5), polymer n is represented by representing one or more), the structural formula (2) ## STR2 ## (Wherein, R1, R2, each hydrogen R3 and R4, methyl, ethyl, isopropyl, 2-hydroxyethyl _{-CH 2 CH 2 (OCH 2 CH} 2) x OH (X 0~
6) or 2-hydroxylethyl-CH ₂ CH ₂ (OC
_{CH 2 CH 2) x OH (} X represents Less than six), R5 is _{(CH 2) 2 -O- (CH} 2) 2, (CH 2) 2 -O-
_{(CH 2) 2 -O- (CH} 2) 2 or CH ₂ -CHOH
It represents _{-CH 2 -O-CH 2 -CHOH-} CH 2, n
Is 1 or more, and Y is S or O), a structural formula (3): (Wherein, R1, R2, each hydrogen R3 and R4, methyl, ethyl, isopropyl, 2-hydroxyethyl _{-CH 2 CH 2 (OCH 2 CH} 2) x OH (X 0~
6) or 2-hydroxylethyl-CH ₂ CH ₂ (OC
_{CH 2 CH 2) x OH (} X represents Less than six), R5 is _{(CH 2) 2 -O- (CH} 2) 2, (CH 2) 2 -O-
_{(CH 2) 2 -O- (CH} 2) 2 or CH ₂ -CHOH
It represents _{-CH 2 -O-CH 2 -CHOH-} CH 2, n
Represents one or more, and Y represents S or O), a polymer represented by the structural formula (4): (Wherein each hydrogen R1 and R2, methyl, ethyl, isopropyl, butyl, -CH ₂ CH ₂ (OCH ₂
CH ₂ ) _X OH (X is 0 to 5) or —CH ₂ CH ₂ (O
CCH ₂ CH ₂ ) _X OH (X represents 0 to 5), n represents 1 or more, and Y represents O or S) as a monomer, a structural formula (5): (Wherein R1 or R2 represents hydrogen, methyl, ethyl, butyl or isobutyl, and R3 is CH ₂ , C ₂ H ₄ or C
₃ H ₆ ), represented by the structural formula (6): (Wherein R1 and R2 each represent hydrogen or carbon atoms of 10
A polymer represented by the following alkyl), structural formula (7): (Wherein, R1, R2, R3 and R4 each represent hydrogen or an alkyl having C of 5 or less, X represents an inorganic anion, Y represents S or O), and a structural formula ( 8) Wherein R 1, R 2, R 3 and R 4 each represent hydrogen or alkyl having 5 or less carbon atoms, X represents an inorganic anion, and Y represents S or O. A plating bath for zinc or a zinc alloy containing one or more selected types. 2. The plating bath for zinc or zinc alloy according to claim 1, further comprising an appropriate amount of aldehyde. 3. The conductive salt is sodium hydroxide,
3 to 80 g / L of zinc and 30 to 25 of sodium hydroxide
The zinc or zinc alloy plating bath according to claim 1 or 2, comprising 0 g / L, 0.01 to 200 g / L of a silicon compound, and 0.1 to 50 g / L of a bath-soluble polymer. 4. The metal as the alloy component is iron, cobalt, nickel, trivalent chromium or copper.
A plating bath for zinc or a zinc alloy according to claim 1. 5. A conductive base material is immersed in the plating bath for zinc or zinc alloy according to any one of claims 1 to 4, and a surface of the base material is plated to a desired thickness. Plating process. 6. The plating process according to claim 5, wherein a passivation treatment is further performed after the plating. 7. The soluble polymer represented by the structural formula (1): (Wherein R 1 and R 2 are hydrogen, methyl, ethyl, isopropyl, butyl, —CH ₂ CH ₂ (OCH ₂ CH ₂ ) _X O
H (X is 0-5) or -CH ₂ CH ₂ (OCCH ₂ CH
_{2) X} OH (X represents 0-5), polymer n is represented by representing one or more), the structural formula (2) embedded image (Wherein, R1, R2, each hydrogen R3 and R4, methyl, ethyl, isopropyl, 2-hydroxyethyl _{-CH 2 CH 2 (OCH 2 CH} 2) x OH (X 0~
6) or 2-hydroxylethyl-CH ₂ CH ₂ (OC
_{CH 2 CH 2) x OH (} X represents Less than six), R5 is _{(CH 2) 2 -O- (CH} 2) 2, (CH 2) 2 -O-
_{(CH 2) 2 -O- (CH} 2) 2 or CH ₂ -CHOH
It represents _{-CH 2 -O-CH 2 -CHOH-} CH 2, n
Is 1 or more, and Y is S or O), a structural formula (3): (Wherein, R1, R2, each hydrogen R3 and R4, methyl, ethyl, isopropyl, 2-hydroxyethyl _{-CH 2 CH 2 (OCH 2 CH} 2) x OH (X 0~
6) or 2-hydroxylethyl-CH ₂ CH ₂ (OC
_{CH 2 CH 2) x OH (} X represents Less than six), R5 is _{(CH 2) 2 -O- (CH} 2) 2, (CH 2) 2 -O-
_{(CH 2) 2 -O- (CH} 2) 2 or CH ₂ -CHOH
It represents _{-CH 2 -O-CH 2 -CHOH-} CH 2, n
Represents one or more, and Y represents S or O), a polymer represented by the structural formula (4): (Wherein each hydrogen R1 and R2, methyl, ethyl, isopropyl, butyl, -CH ₂ CH ₂ (OCH ₂
CH ₂ ) _X OH (X is 0 to 5) or —CH ₂ CH ₂ (O
CCH ₂ CH ₂ ) _X OH (X represents 0 to 5), n represents 1 or more, and Y represents O or S) as a monomer, a structural formula (5): (Wherein R ₁ or R ₂ represents hydrogen, methyl, ethyl, butyl or isobutyl, and R ₃ is CH ₂ , C ₂ H ₄ or C _2
3 H ₆ ), represented by the structural formula (6): (Wherein R1 and R2 each represent hydrogen or carbon atoms of 10
A polymer represented by the following alkyl), structural formula (7): (Wherein, R1, R2, R3 and R4 each represent hydrogen or an alkyl having C of 5 or less, X represents an inorganic anion, Y represents S or O), and a structural formula ( 8) Wherein R 1, R 2, R 3 and R 4 each represent hydrogen or alkyl having 5 or less carbon atoms, X represents an inorganic anion, and Y represents S or O. An additive for a zinc or zinc alloy plating bath containing one or more selected zinc salts, optionally further containing a silicon compound, wherein the total amount of the bath-soluble polymer is 10 to 950 g / kg. Or an additive for a zinc alloy plating bath.