KR100419658B1 - An additive for chloride zn-fe alloy electrodeposite and chloride zn-fe alloy electrodeposite solution containg the same - Google Patents

Abstract

An additive used in a chloride-based zinc-iron plating bath and a chloride-based zinc-iron plating solution composition containing the same,

A polyethylene glycol polymerization degree of _{10-20 (H (OCH 2 CH 2} ) n OH) and polyethylene glycol _{(H (OCH 2 CH 2)} n OH) a degree of polymerization of 20 to 30 is 1: 2-1: 5 mixture by weight Polyethylene mixture having a concentration of 5-15% by weight in the aqueous solution; Obaniline 0.02-0.2 g / l; Benzoic acid at the same concentration as obaniline; And additives for chloride-based zinc-iron plating solution with 0.5-30 g / l citric acid, 0.5-2.5 mol / l zinc ion molarity, 0.1-0.5 mol / l iron ion molarity of iron chloride, and mol of chloride ion. Chloride with the additive added in an amount of 0.2-8.0 mL / L in a chloride-based zinc-iron alloy electroplating solution having a concentration of 4.0-9.0 mol / L and an iron ion: (iron ion + zinc ion) ratio of 0.05-0.3: 1. A zinc-iron alloy electroplating solution composition is provided.

By plating using the acid chloride-based zinc-iron plating solution composition to which the additive of the composition of the present invention is added, plating grains are fine and uniform, improving roughness, and having excellent surface appearance and gloss precipitation rate such as gloss and whiteness. A plating layer can be manufactured.

Description

Additives for chloride-based zinc-iron alloy plating and composition for chloride-based zinc-iron alloy plating TECHNICAL FIELD

The present invention relates to an additive used in a chloride-based zinc-iron plating bath and a chloride-based zinc-iron plating solution composition containing the same, and more particularly, roughness, surface appearance, and iron precipitation of the plating layer during chloride-based zinc-iron plating. The present invention relates to an additive used in a chloride-based zinc-iron plating bath and a chloride-based zinc-iron plating solution composition containing the same to improve the rate.

In order to improve the corrosion resistance of the steel sheet is generally plated with zinc, and electroplated steel sheet manufactured by plating with electric force is widely used in the fields of home appliances, automobiles, construction, and the like. However, in order to secure corrosion resistance in a harsh atmosphere, the thickness of the galvanized layer should be increased, thereby increasing the cost and degrading the quality characteristics such as plating adhesion, processability, weldability, and paintability.

In order to improve this problem, zinc-based alloy electroplating has been developed, mainly for automotive steel plates. Among them, zinc-iron alloy electroplating material is known as a plating material excellent in corrosion resistance, workability, coating properties. The zinc-iron plating method has been proposed in various ways depending on the components of the plating bath, but the plating solution based on the acid bath is divided into sulfide bath and chloride bath.

Chloride baths have better electrical conductivity than sulfide baths, which enables high current density plating and the use of soluble anodes makes solution management easier and less expensive than sulfides using insoluble anodes.

However, zinc-iron alloy electroplating products of chloride baths using soluble anodes have poor conductivity due to partial preferential precipitation and good sludge, resulting in sludge in the plating solution, resulting in poor surface appearance such as whiteness and glossiness. The precipitation of iron tends to change rapidly.

In order to improve the surface appearance of conventional zinc-iron alloy plating, Japanese Patent No. 57-114686 discloses metal coprecipitation by adding polyamine or polyvinyl alcohol when alloy plating with iron group metal (Fe, Ni, Co, etc.) mainly composed of zinc. In order to improve workability, economics and glossiness, plating adhesion and surface roughness are not improved.

Japanese Patent No. 64-47893 improves the surface uniformity and appearance color tone by adding substituted polyethers as an additive, but there is a problem that the surface of the plating layer is rough and the iron precipitation rate is low.

In addition, Japanese Patent No. 64-47892 improves the water-tightness of the plating layer, the chemical conversion treatment, the upper iron content, etc. by adding polyethylene glycol, which is a nonionic surfactant, and has a problem of poor surface appearance.

It is therefore an object of the present invention to provide an additive for a chloride-based zinc-iron plating solution that provides improved plating roughness, surface appearance and iron deposition rate.

Another object of the present invention is to provide a chloride-based zinc-iron plating solution composition containing the additive of the present invention.

According to one aspect of the invention,

A polyethylene glycol polymerization degree of _{10-20 (H (OCH 2 CH 2} ) n OH) and polyethylene glycol _{(H (OCH 2 CH 2)} n OH) a degree of polymerization of 20 to 30 is 1: 2-1: 5 mixture by weight Polyethylene mixture having a concentration of 5-15% by weight in the aqueous solution;

Obaniline 0.02-0.2 g / l;

Benzoic acid at the same concentration as obaniline; and

0.5-30 g / l citric acid,

An additive for a chloride-based zinc-iron plating solution is provided.

According to another aspect of the present invention,

The zinc ion molar concentration of zinc chloride is 0.5-2.5 mol / l, the iron ion molar concentration of iron chloride 0.1-0.5 mol / l, the molar concentration of chloride chloride 4.0-9.0 mol / l and the iron ion: (iron + zinc ion) A chloride-based zinc-iron alloy electroplating solution composition in which the additive of the present invention is added in an amount of 0.2-8.0 ml / L to a chloride-based zinc-iron alloy electroplating solution having a ratio of 0.05-0.3: 1 is provided.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

The additive for zinc-iron alloy electroplating solution composed of the polyethylene glycol mixture, benzoic acid, obaniline, and citric acid of the present invention is used by adding it to the plating solution, thereby improving surface appearance and iron deposition rate such as roughness, glossiness and whiteness of the plating layer. Is improved.

The reason for limiting the action and the content of each component constituting the additive for zinc-iron alloy electroplating solution of the present invention is as follows.

Polyethylene is a polyethylene glycol polymerization degree of 10 to 20 as a glycol _{(H (OCH 2 CH 2)} n OH) and having a degree of polymerization of 20 to 30 polyethylene glycol _{(H (OCH 2 CH 2)} n OH) is 1: 2-1: Polyethylene glycol mixtures mixed in a 5 weight ratio are used.

When polyethylene glycol having a degree of polymerization (n value) of polyethylene glycol is 10 or less, the plating becomes rough and the iron precipitation rate is insignificant, and when polyethylene glycol having a number of n or more is used, the effect of improving the surface appearance of the plating layer is reduced. The reason why the polyethylene glycol having a degree of polymerization of 10-20 and the polyethylene glycol having a degree of polymerization of 20-30 is mixed and used is the same as the reason for limiting the n value. The larger the n number, the better the surface roughness, but the lower the surface appearance improvement effect such as glossiness and whiteness. The polyethylene glycol mixture constituting the additive is used in a concentration of 5-15% by weight in an aqueous solution. When the concentration is 5% by weight or less, the microcrystallization effect of the plating crystals is small, and the adhesion is inferior. When the concentration is 15% by weight or more, the surface appearance improvement effect of the plating layer is reduced.

Ovanillin is mixed in an amount of 0.02-0.2 g / l, respectively. When the amount of ovaniline is 0.02 g / l or less, the plating current efficiency and glossiness cannot be improved. At 0.2 g / l or more, the adhesion of the plating layer is reduced and the surface becomes black.

Furthermore, when the benzoic acid and the obaniline deviate from the 1: 1 concentration ratio, the surface appearance is not good, and when added in a 1: 1 concentration ratio, it shows excellent roughness. Therefore, benzoic acid is added in the same concentration ratio as the obaniline.

For the additives citric acid is added in an amount of 0.5-30 g / l. If the amount of citric acid is less than 0.5g / ℓ does not improve the surface appearance and should be more than 0.5g / ℓ to improve the surface appearance due to the reduction of sludge in the plating solution. However, when the content of citric acid is more than 30g / ℓ plating current efficiency is deteriorated and the surface yellowing is not preferable.

The chloride-based zinc-iron plating solution additive prepared as described above has the desired physical properties when added in the chloride-based zinc-iron plating solution.

In other words, the additive is a zinc chloride molar concentration of 0.5-2.5 mol / l, iron chloride molar concentration of 0.1-0.5 mol / l, chloride chloride molar concentration of 4.0-9.0 mol / l and iron ion: (iron ion: + Zinc ion) is added to the chloride-based zinc-iron plating solution having a ratio of 0.05-0.3: 1.

If the molar concentration of zinc ions in the plating solution is 0.5 mol / l or less, burning may be blackened due to the lack of concentration of the ions to be coated, and in the case of 2.5 mol / l or more, the plating layer is powder-plated. Adhesion is inferior, iron content of a plating layer falls, and corrosion resistance is inferior.

If the molar concentration of iron ions is less than 0.1 mol / l, the iron content of the plating layer is decreased, and weldability and paintability are deteriorated. Degrades.

When the chlorine ion has a molar concentration of 4.0 mol / l or less, a large amount of burning occurs due to a decrease in electrical conductivity, and at 9.0 mol / l or more, chlorine ions are precipitated, resulting in poor plating workability and difficulty in managing the concentration of the plating solution.

Zinc-iron alloy electroplating is excellent in corrosion resistance and workability in the iron content of the plated layer in the 4-30% range, and more preferable in the 10-20% range.

Therefore, when the iron ion: (iron ion + zinc ion) ratio is 0.05 or less, the iron content is lowered to 4% or less in the plating layer, and at 0.3 or more, the iron content is lowered to 30% or more and the corrosion resistance and workability are lowered.

The additive of the present invention is added in an amount of 0.2-8.0 ml / l, preferably 1.0-4.0 ml / l, relative to the total zinc-iron plating solution formulated as described above.

When the content of the added additive is 0.2ml / l or less, it is not expected to improve the roughness and surface appearance by the refinement of the plating grains, and when it is more than 8.0ml / l, the current efficiency is lowered, the surface becomes darker, and the plating adhesion is deteriorated. The additive is preferably added to the plating bath in an amount of 0.2 to 8.0 ml / l, and particularly when added in an amount of 1.0 to 4.0 ml / l.

The chloride-based zinc-iron plating solution to which the additive of the present invention is added is, for example, pH 1.0-5.0 on a steel sheet, the temperature of the plating liquid is 40-70 ° C, the current density is 20-200 A / dm ^2, and 0.1-2.5m / sec can be applied to the steel sheet.

The chloride-based zinc-iron plating solution containing the additive of the present invention can be applied regardless of the type, shape, etc. of the metal to be plated, and particularly, excellent plating quality can be easily obtained when continuous electric zinc plating is required for high current density plating. Can be.

Hereinafter, the present invention will be described in detail with reference to Examples.

Using a cold-rolled steel sheet as a base metal, the plating solution having the composition shown in Table 1 was plated so that the plating amount was 40 g / cm 2 dl. At this time, the roughness difference between the plating layer and the base layer, the whiteness, glossiness, and precipitation rate of iron ions of the plating layer were measured. Indicated.

The plating conditions used in this example were pH = 2, temperature = 60 ° C., relative flow rate = 1.5 m / sec and current density = 60 A / cm 2.

number Additive (ml / l) Polyethylene glycol Obaniline (g / ℓ) Citric Acid (g / ℓ) Obaniline: The ratio of benzoic acid Plating layer roughness Plating layer Glossiness Whiteness number of n the ratio of n to other Concentration (wt%) A B A: B One 2.0 15 25 1: 2 12.0 0.05 10 1: 1 Good Good Good Good 2 10 25 1: 3 Good Good Good Good 3 15 25 1: 3 Good Good Good Good 4 15 30 1: 3 Good Good Good Good 5 15 25 1: 5 Good Good Good Good 6 15 25 1: 3 Good Good Good Good 7 15 25 1: 3 10.0 Good Good Good Good 8 15 25 1: 3 15.0 Good Good Good Good 9 15 25 1: 3 12.0 Good Good Good Good 10 15 25 1: 3 Good Good Good Good 11 15 25 1: 3 Good Good Good Good 12 15 25 1: 3 Good Good Good Good 13 8 25 1: 3 Bad Bad Good Good 14 15 35 1: 3 Bad Good Bad Bad 15 15 25 1: 1 Bad Bad Bad Bad 16 15 25 1: 6 Bad Good Bad Bad 17 15 25 1: 3 1.0 Bad Bad Good Bad 18 15 25 1: 3 5.0 Good Good Good Good 19 15 25 1: 3 15.0 Good Good Good Good 20 15 25 1: 3 16.0 Bad Good Bad Bad 21 15 25 1: 3 12.0 0.01 Bad Bad Bad Bad 22 15 25 1: 3 0.02 Good Good Good Good 23 10 52 1: 3 0.1 Good Good Good Good 24 15 25 1: 3 0.15 Good Good Good Good 25 15 25 1: 3 0.20 Good Good Bad Bad 26 15 25 1: 3 0.21 0.3 Bad Bad Bad Bad 27 15 25 1: 3 0.05 0.5 Good Good Good Good 28 15 25 1: 3 25 Good Good Good Good 29 15 25 1: 3 30 Good Good Good Good 30 15 25 1: 3 31 Bad Bad Bad Bad 31 15 25 1: 3 5.0 10 1: 2 Good Bad Bad Bad 32 15 25 1: 3 15.0 1: 0.5 Good Bad Bad Bad 33 0.1 15 25 1: 3 12.0 1: 1 Bad Bad Bad Bad 34 0.2 15 25 1: 3 Good Good Good Good 35 8.0 15 25 1: 3 Good Good Good Good 36 9.0 15 25 1: 3 Bad Bad Bad Bad

* Plating layer roughness: Plating layer roughness> Disc roughness: Poor, Plating layer roughness≤ disc roughness: Good

** Iron deposition rate: Fe content = 98% or more good in the plating layer Fe content / plating solution, or less

*** Whiteness: L value of Color Difference Meter

(Good: 69 or more, poor: 68 or less)

**** Glossiness: Polisher (good: more than 66, poor: less than 65)

As shown in Table 1, the plating adhesion, the iron deposition rate of the plating layer, the surface appearance (glossiness and whiteness) is good under the conditions in accordance with the present invention, but the plating layer carried out in the plating solution conditions outside the scope of the invention The condition was bad.

As described above, by plating using an acid chloride-based zinc-iron plating solution composition to which the additive of the composition of the present invention is added, the plating grains are fine and uniform to improve roughness, and the surface appearance of glossiness and whiteness, etc. A plating layer excellent in iron deposition rate can be obtained.

Claims (2)

Polymerization degree (wherein n value) is 10 to 20 polyethylene glycol (H (OCH ₂ CH _{2) n} OH) and having a degree of polymerization of 20 to 30 polyethylene glycol (H (OCH ₂ CH _{2) n} OH) is 1: 2-1 Polyethylene mixture having a concentration of 5-15% by weight in an aqueous solution mixed at a ratio of 5% by weight; Obaniline 0.02-0.2 g / l; Benzoic acid in the same concentration ratio as obaniline; And Citric acid at 0.5-30 g / l; Additive for chloride-based zinc-iron alloy electroplating solution. The zinc ion molar concentration of zinc chloride is 0.5-2.5 mol / l, the iron ion molar concentration of iron chloride 0.1-0.5 mol / l, the molar concentration of chloride chloride 4.0-9.0 mol / l and the iron ion: (iron + zinc ion) A chloride-based zinc-iron alloy plating solution composition in which the additive of claim 1 is added in an amount of 0.2-8.0 ml / l to a zinc-iron alloy electroplating solution having a ratio of 0.05-0.3: 1.