KR100979047B1 - Electro-Galvanizing Additive for Excellent Adhesion, Flatness and Surface Appearance, Manufacturing Method Thereof and Plating Method Using it - Google Patents

Abstract

The present invention in weight percent, methoxy polyethylene glycol (CH ₃ (OCH ₂ CH ₂ ) _n OH) 5-15%, sodium sulfonate (CH ₂ = CHCH ₂ SO ₃ Na)-sodium bicarbonate mixture 2-8% and It provides an electro zinc plating additive, a method for preparing the additive, and a plating method using the same, comprising the balance water. In this case, the n value of methoxy polyethylene glycol is 10 to 30, the sodium sulfonate: sodium bicarbonate ratio in the sodium sulfonate-sodium bicarbonate mixture may be limited to 1: 0.2 to 0.6, and the additive of the present invention at the time of plating 0.1 to 4 mL may be added per liter of plating solution.

The additive of the present invention can be applied to electro zinc plating using an acid chloride bath irrespective of the type and shape of the metal to be plated, and is particularly useful for improving plating quality in continuous electro zinc plating of steel sheets requiring high current density plating. .

Electro zinc plating, plating solution, roughness, whiteness, adhesion, glossiness

Description

Electro-Galvanizing Additive for Excellent Adhesion, Flatness and Surface Appearance, Manufacturing Method Thereof and Plating Method Using it}

The present invention relates to an additive used in electro zinc plating, a method for preparing the same, and a plating method using the same, and more particularly, to methoxy polyethylene glycol (CH ₃ (OCH ₂ CH ₂ ) _n OH) and sodium sulfonate (CH ₂ =). An additive for preparing an electro-zinc plating composition comprising a CHCH ₂ SO ₃ Na) -sodium bicarbonate mixture and the balance water, and an additive capable of securing excellent surface quality of a coated steel sheet using the same, a manufacturing method thereof, and a plating using the same It is about a method.

Electro-zinc plating materials have many advantages in terms of ease of plating, cost, corrosion resistance, etc. are widely used as materials for home appliances, construction, and automobiles. In order to improve the productivity of the electro-zinc plating material, plating with high current density is essential, and when used for post-treatment, an excellent surface appearance having a beautiful and flat plating layer is required. Furthermore, the adhesion should be excellent so that peeling of the plating layer does not occur in the place where the processing for the final product is performed.

Chlorinated baths, sulfate baths, cyan baths and neutral salt baths are used as electrogalvanizing baths. Of these, the chloride bath is suitable for high current density plating because of its excellent electrical conductivity, but the surface appearance of the plating layer is relatively poor, and the surface may be rough, resulting in poor flatness. There is a disadvantage of losing. In addition, if the plating amount is increased to improve the corrosion resistance, the plating layer may be dropped during deep processing, which may damage the mold and reduce the corrosion resistance of the mold.

Therefore, in order to improve this disadvantage, the prior art used an additive when using a chloride bath. For example, US Pat. No. 4,075,066 improves the plating properties by adding at least one polyoxalalkylate naphthol and at least one aromatic carboxylic acid or salt for distribution of gloss, ductility and good plating current of the plating layer in ammonia free plating bath. U.S. Patent No. 4,146,441 discloses a technique for adding a mixture of formaldehyde to expand the range of plating current density in order to improve the glossiness of the plating layer and ease of plating. In addition, U.S. Patent 4,049,510 has been shown to improve glossiness by adding an amine polymer in a chloride bath, and U.S. Patent 3,855,085 discloses that a surface gloss improvement effect is obtained by adding a nonionic polyoxyethylene in a chloride bath. It was.

In addition, Japanese Patent No. 58-48639 discloses a method of selectively using ammonium chloride, potassium chloride, sodium chloride, aluminum chloride, barium chloride, calcium chloride, magnesium chloride, and the like to change plating conditions. In 204389, the addition of amino acids, additives such as glycine and hydroxyproline have been shown to improve the gloss.

However, the prior arts are mainly limited to improving the surface appearance of the galvanized layer, and in addition to the surface appearance of the galvanized layer, there is a problem in that it is insufficient to improve complex quality improvement such as adhesion and flatness.

In addition, Japanese Patent Laid-Open No. Hei 8-165593 discloses a method of depositing a thin Ni plating layer before galvanizing in order to obtain a uniform and flat plating layer, but this treatment has a problem of causing an increase in cost. In addition, Japanese Patent Laid-Open Nos. 2001-115295 and 9-195082 improve the surface appearance by adding a metallic element as an impurity in a sulfate plating bath, but when the patented technology is used in a chloride bath, the surface whiteness is reduced by plating the impurities. It can be used only in sulfate baths.

The present invention solves the problems of the prior art described above, and also the plating bath additive and zinc electroplating using the same to improve the surface appearance and surface flatness (roughness) of the plating layer in the chloride-based galvanizing bath, such as whiteness or glossiness. It is intended to provide a plating method.

To this end, the present invention in the weight percent, methoxy polyethylene glycol (CH ₃ (OCH ₂ CH ₂ ) _n OH) 5-15%, sodium sulfonate (CH ₂ = CHCH ₂ SO ₃ Na)-sodium bicarbonate mixture 2 ~ It provides an additive for electro-galvanizing comprising 8% and the balance water. In this case, the n value of the methoxy polyethylene glycol may be limited to 10 to 30, and the ratio of sodium sulfonate to sodium bicarbonate in the sodium sulfonate-sodium bicarbonate mixture may be limited to 1: 0.2 to 0.6.

Furthermore, the present invention provides, by weight%, methoxy polyethylene glycol (CH ₃ (OCH ₂ CH ₂ ) _n OH) 5 to 15%, sodium sulfonate (CH ₂ = CHCH ₂ SO ₃ Na) -sodium bicarbonate mixture 2 to 8 It provides a method for producing an electro-zinc plating additive, characterized in that the addition of% and the balance water, and stirring for a time of about 300 seconds or more in the temperature range of room temperature ~ 60 ℃. In this case, the n value of the methoxy polyethylene glycol may be limited to 10 to 30, and the ratio of sodium sulfonate to sodium bicarbonate in the sodium sulfonate-sodium bicarbonate mixture may be limited to 1: 0.2 to 0.6.

Further, the present invention, in the method of plating a steel sheet using a chloride-based electrogalvanizing bath, by weight%, 5 to 15% methoxy polyethylene glycol (CH ₃ (OCH ₂ CH ₂ ) _n OH), sodium sulfonate ( Electroplating additives containing 2 to 8% of CH ₂ = CHCH ₂ SO ₃ Na) -sodium bicarbonate and the balance of the additives are added to the chloride-based electro zinc plating bath at 0.1 to 4 mL / L and plated. It provides a plating method characterized by. In this case, the n value of the methoxy polyethylene glycol may be limited to 10 to 30, and the ratio of sodium sulfonate to sodium bicarbonate in the sodium sulfonate-sodium bicarbonate mixture may be limited to 1: 0.2 to 0.6.

The additive of the present invention can be applied to electro zinc plating using an acid chloride bath irrespective of the type and shape of the metal to be plated, and is particularly useful for improving plating quality in continuous electro zinc plating of steel sheets requiring high current density plating. .

The present invention improves the adhesion of the plating layer during the zinc electroplating in the chloride bath, and controls the shape and size of the microstructure to change the deposition direction of the plated surface by crystal grains, electroplating material and after-treatment products (phosphate Treatment, chromium treatment and coating)) and the plating method using the same.

The additive of the present invention is prepared by mixing methoxy polyethylene glycol (CH ₃ (OCH ₂ CH ₂ ) _n OH) with a sodium sulfonate-sodium bicarbonate mixture and water, more preferably in the temperature range of room temperature to 60 ℃ Prepared by stirring for at least 300 seconds. In the present invention, the methoxy polyethylene glycol is added in an amount of 5 to 15% by weight, in particular, the n value is limited to 10 to 30. Here, the sum of the components of sodium salt condensed naphthalene sulfonic acid (CH ₂ = CHCH ₂ SO ₃ Na) and sodium bicarbonate in a ratio of 0.2 to 0.6 is comprised of 2 to 8% by weight and the balance of water. . In another aspect, the present invention provides a method for plating the additive by adding 0.1 ~ 4mL / L to the acid chloride-based galvanizing bath.

Hereinafter will be described in more detail with respect to the component system constituting the additive of the present invention.

The methoxy added to the present invention The n value of polyethylene glycol is limited to 10-30. If N is less than 10, the particle formation site of the plating crystals due to their adsorption cannot be clearly provided, resulting in deterioration of particle micronization effect and poor flatness, whereas in excess of 30, current blocking by additives This is because the excessive increase may interrupt the uniform current flow and reduce whiteness and glossiness.

In addition, the methoxy polyethylene glycol is added 5 to 15% by weight in an aqueous solution. If the content of methoxy polyethylene glycol is less than 5% by weight, the microcrystallization effect of the plating crystal is insignificant and the surface may be rough or poor adhesion. On the other hand, if the content is more than 15% by weight, the precipitation of the plated particles may be disturbed to cause a ballistic plating phenomenon in which hydrogen is generated, and the surface white may be darkened.

Sodium sulfonate and sodium bicarbonate included in the present invention to prepare an additive is controlled in a ratio of 1: 0.2 to 0.6. If the content of sodium bicarbonate is too small, there is no effect of improving the flatness of the plating layer, while if too much, the adhesion may be reduced, so the ratio is limited.

The amount added in the aqueous solution of sodium sulfonate and sodium bicarbonate is controlled to 2 to 8% by weight. If the sum of these components is less than 2% by weight, the above-described effects cannot be obtained, whereas if it exceeds 8% by weight, edge ballistic plating may occur during high current (120 ASD or more) plating.

The additive of the present invention is used to improve the surface quality of the plating layer by adding an appropriate amount during plating. To this end, 0.1 to 4 mL / L is added based on the capacity of the plating bath. If the amount of the additive is less than 0.1mL / L, it is difficult to enjoy the effect of adding the additive of the present invention, whereas if it exceeds 4ml / L, the adhesion may be inferior due to excessive surface adsorption, and black burnt on the surface during plating. Patterns may occur.

When an appropriate amount of the additive of the present invention is added, the particle fineness that influences the surface appearance of the plating layer, the orientation and plating properties (overvoltage rise) can be appropriately improved when the plating layer is formed, and thus the plating layer adhesion, whiteness, glossiness, etc. It can be ensured, and furthermore, good roughness by formation of a uniform plating layer can be obtained, and an improved surface appearance can be obtained.

(Example)

Hereinafter, the present invention will be described in more detail with reference to the following examples.

Electroplating was performed using the cold rolled steel sheet as the base metal under the plating solution concentrations and plating conditions shown in Table 1, and then the results of measuring the adhesion of the plating layer, the glossiness of the surface, the whiteness, and the flatness (surface roughness) were compared. In the present embodiment, the concentration and plating conditions of the plating solution were Zn: 90 g / L, Cl: 250 g / L, plating amount: 20 g / m ² , temperature 60 ^° C., pH: 4.5, and current density of 100 A / dm ² .

Plating material Methoxy polyethylene glycol Sulfonate Titanium:
Sodium Bicarbonate
(weight%)
vanillin
(g / L) additive
(mL / L) Adhesion surface
Exterior surface
Roughness n density
(weight%) Mutual expenses density
(weight%) Glossiness Whiteness Comparative Example 1 9 10 1: 0.5 5 0.5 Good Bad Bad Bad Experimental Example 1 10 10 1: 0.5 5 0.5 Good Good Good Good Experimental Example 2 15 10 1: 0.5 5 0.5 Good Good Good Good Experimental Example 3 20 10 1: 0.5 5 0.5 Good Good Good Good Experimental Example 4 25 10 1: 0.5 5 0.5 Good Good Good Good Experimental Example 5 30 10 1: 0.5 5 0.5 Good Good Good Good Comparative Example 2 31 10 1: 0.5 5 0.5 Bad Bad Bad Bad Comparative Example 3 20 4 1: 0.5 5 0.5 Good Bad Bad Bad Experimental Example 6 20 5 1: 0.5 5 0.5 Good Good Good Good Experimental Example 7 20 15 1: 0.5 5 0.5 Good Good Good Good Comparative Example 4 20 16 1: 0.5 5 0.5 Bad Bad Bad Bad Comparative Example 5 20 10 1: 0.1 5 0.5 Bad Bad Bad Bad Experimental Example 8 20 10 1: 0.2 5 0.5 Good Good Good Good Experimental Example 9 20 10 1: 0.6 5 0.5 Good Good Good Good Comparative Example 6 20 10 1: 0.7 5 0.5 Bad Bad Bad Bad Comparative Example 7 20 10 1: 0.5 One 0.5 Bad Bad Bad Bad Experimental Example 10 20 10 1: 0.5 2 0.5 Good Good Good Good Experimental Example 11 20 10 1: 0.5 8 0.5 Good Good Good Good Comparative Example 8 20 10 1: 0.5 9 0.5 Bad Bad Bad Bad Comparative Example 9 20 10 1: 0.5 5 0.05 Bad Bad Bad Bad Experimental Example 12 20 10 1: 0.5 5 0.1 Good Good Good Good Experimental Example 13 20 10 1: 0.5 5 4.0 Good Good Good Good Comparative Example 10 20 10 1: 0.5 5 4.1 Bad Bad Bad Bad

In the evaluation of the properties of the plated layer shown in Table 1, the plated adhesion was carried out through a peel test after tape 0 T bending, and when the plated layer did not adhere to the tape, it was determined to be "good", and when it was found to be "poor". In addition, the glossiness measured by the glossmeter was shown as good, less than 23, the bad, and the whiteness measured by the color difference meter was 85 or more, and less than that as a bad. The plating layer roughness evaluated the case where the roughness of the plated layer was low compared with the base steel plate roughness before plating as being favorable or less.

According to this embodiment, when the plating treatment by adding the appropriate amount of the additive of the present invention it was possible to obtain an electrogalvanized steel sheet excellent in adhesion, surface appearance and surface roughness as shown in Table 1 above. On the other hand, when the composition of the additive is out of the scope of the present invention or the amount of addition is not appropriate, the results did not satisfy these properties.

As a result, it was found that when using the additive of the present invention, an electrogalvanized steel sheet exhibiting excellent surface quality could be produced.

Claims (9)

By weight, methoxy polyethylene glycol (CH ₃ (OCH ₂ CH ₂ ) _n OH) 5-15% (where n = natural water), sodium sulfonate (CH ₂ = CHCH ₂ SO ₃ Na) -sodium bicarbonate mixture 2 An additive for electro galvanizing, comprising ~ 8% and the balance water. The additive according to claim 1, wherein the n-value of the methoxy polyethylene glycol is 10 to 30. The additive according to claim 1, wherein the ratio of sodium sulfonate to sodium bicarbonate in the sodium sulfonate-sodium bicarbonate mixture is 1: 0.2 to 0.6. By weight, methoxy polyethylene glycol (CH ₃ (OCH ₂ CH ₂ ) _n OH) 5-15% (where n = natural water), sodium sulfonate (CH ₂ = CHCH ₂ SO ₃ Na) -sodium bicarbonate mixture 2 Add ~ 8% and the balance water, Method of producing an additive for electro-galvanizing, characterized in that the stirring for 300 seconds or more in the temperature range of 20 ~ 60 ℃. 5. The method of claim 4, wherein the n-value of the methoxy polyethylene glycol is 10 to 30. The method of claim 4, wherein the sodium sulfonate: sodium bicarbonate ratio in the sodium sulfonate-sodium bicarbonate mixture is 1: 0.2 to 0.6. In the method of plating a steel sheet using a chloride-based galvanizing bath, By weight, methoxy polyethylene glycol (CH ₃ (OCH ₂ CH ₂ ) _n OH) 5-15% (where n = natural water), sodium sulfonate (CH ₂ = CHCH ₂ SO ₃ Na) -sodium bicarbonate mixture 2 Plating method characterized in that the electroplating additives containing ˜8% and the balance water to be added to the chloride-based electro zinc plating bath at 0.1 to 4mL / L to plate. The plating method according to claim 7, wherein the n value of the methoxy polyethylene glycol is 10 to 30. 8. A plating method according to claim 7, wherein the ratio of sodium sulfonate to sodium bicarbonate in the sodium sulfonate-sodium bicarbonate mixture is 1: 0.2 to 0.6.