TWI645072B - Aqueous composition for treating metallic surface, method of treating surface, protective film and surface-treated galvanized steel sheet - Google Patents

Abstract

An aqueous composition for metal surface treatment, a surface treatment method, a protective film, and a surface-treated galvanized steel sheet, the aqueous composition comprising a water-soluble zirconium compound (A), a decane coupling agent (B), and a fluorine-containing compound (C) A phosphoric acid compound (D), a metal compound (E), and a water-dispersible resin (F). The water-dispersible resin (F) has a specific property to form a protective film thus formed and has excellent process corrosion resistance.

Description

Aqueous composition for metal surface treatment, surface treatment method, protective film and surface treated galvanized steel sheet

The present invention relates to the field of surface treatment, and in particular to an aqueous composition for metal surface treatment, a surface treatment method, a protective film, and a surface treated galvanized steel sheet. By the above aqueous composition and surface treatment method, a protective film having excellent corrosion resistance, alkali-resistant washing property, lubricity, and post-process corrosion resistance, and a surface-treated galvanized steel sheet containing the above protective film can be obtained.

Galvanized steel sheets have the advantages of corrosion resistance, ease of molding, welding and painting, and are now widely used in various home appliances, electronic products, machinery and construction.

However, the corrosion resistance of the metal surface of the galvanized steel sheet is insufficient, so that the metal surface is still susceptible to infiltration of a corrosion factor (for example, oxygen, water, and/or chloride ions) to induce an electrochemical redox reaction. Causes the above metal surface to be corroded. Further, in the cathode reaction, the above oxygen or water obtains electrons and generates hydroxide ions (OH ^- ), and the anode reaction causes metal ions to be formed due to the loss of electrons on the surface of the metal, resulting in corrosion of the metal surface.

In the past, galvanized steel sheets were surface treated with a surface treatment agent containing chromium (hexavalent chromium or trivalent chromium). Although the corrosion of galvanized steel sheets can be effectively suppressed, the toxicity of chromium is extremely high and causes serious damage to the environment. Therefore, it is rarely used at present.

Instead, various chromium-free surface treatment agents, one of which is a surface treatment agent with vanadium compounds in combination with zirconium, titanium, molybdenum, tungsten, a metal compound of at least one of manganese or cerium, and an etchant (for example, hydrofluoric acid, acetic acid or fluoroantimonic acid) is added. However, the above method has poor corrosion resistance, and it has produced a white rust area of 10% to 30% after 48 hours of the corrosion resistance test, and the above-mentioned surface treatment agent has poor solubility and stability.

There is another method which proposes a surface treatment agent comprising an organic vanadium compound and a phosphorus-containing inorganic acid. However, this surface treatment agent produced a 100% white rust area after a 24 hour corrosion resistance test, so corrosion resistance was also poor.

Still another method is to provide an aqueous metal surface treatment agent comprising a zirconium compound, a cerium compound, a fluorine-containing compound, a phosphoric acid compound, and a water-dispersible resin, wherein the content of the water-dispersible resin is low.

Although the above aqueous metal surface treatment agent can form a protective film having good alkali wash resistance, corrosion resistance, etc., the above protective film still lacks good lubricity, and the protective film is damaged after being processed and deformed, resulting in processing. After the corrosion resistance is reduced.

Therefore, there is an urgent need to propose an aqueous composition for metal surface treatment, a surface treatment method, a protective film, and a surface-treated galvanized steel sheet to solve the above problems.

Therefore, an aspect of the present invention provides an aqueous composition for metal surface treatment, which can form a protective film on a metal surface, thereby improving alkali scratch resistance, corrosion resistance, lubricity, and after processing of the metal. Corrosion resistance.

Another aspect of the present invention provides a surface treatment method which is carried out using the above aqueous composition.

Still another aspect of the present invention provides a protective film formed by the above-described galvanized steel sheet surface treatment method.

In another aspect of the invention, a surface treated galvanized steel sheet comprising a galvanized steel sheet and a protective film formed on the surface of the galvanized steel sheet is provided.

To achieve the above object, the present invention provides an aqueous composition for metal surface treatment comprising: a water-soluble zirconium compound (A), a decane coupling agent (B), a fluorine-containing compound (C), a phosphoric acid compound (D), a metal compound (E), and a water-dispersible resin (F) having a weight average molecular weight of more than 60,000, the water-dispersible resin (F) An elongation at break is between 50% and 150%, and the water-dispersible resin (F) has a glass transition temperature of at least two temperature zones, the at least two temperature zones comprising between -20 and 25 ° C At least one low temperature zone and at least one high temperature zone between 50 and 90 °C. The amount of the decane coupling agent (B) used is 50 parts by weight to 200 parts by weight, and the fluorine-containing compound (C) is used in an amount of 20 parts by weight to 100 parts by weight based on 100 parts by weight of the water-soluble zirconium compound (A). The phosphoric acid compound (D) is used in an amount of from 20 parts by weight to 70 parts by weight, and the metal compound (E) is used in an amount of from 20 parts by weight to 60 parts by weight. Further, the water-dispersible resin (F) may be used in an amount of 70 parts by weight to 90 parts by weight based on 100 parts by weight of the total solid content of the aqueous composition.

In an embodiment of the present invention, the aqueous composition further comprises an emulsifying wax (G), wherein one of the emulsifying wax (G) is used in an amount of 5 parts by weight to 10 parts by weight based on 100 parts by weight of the total solid content. Share.

In one embodiment of the present invention, the water-soluble zirconium compound (A) comprises zirconium nitrate, zirconyl nitrate, zirconium sulfate, zirconium acetate, ammonium zirconium carbonate, sodium zirconium carbonate, potassium zirconium carbonate or any combination thereof.

In one embodiment of the present invention, the decane coupling agent (B) comprises an amino decane coupling agent (B1) and an epoxy decane coupling agent (B2), and the amino decane coupling agent (B1) and the epoxy One weight ratio of the quinone coupling agent (B2) is from 0.3 to 1.2.

In one embodiment of the invention, the amino decane coupling agent (B1) comprises γ-aminopropyltrimethoxydecane, γ-aminopropyltriethoxydecane, N-β (aminoethyl) )-γ-aminopropylmethyldiethoxydecane, N-β(aminoethyl)-γ-aminopropyltrimethoxydecane, N-β(aminoethyl)-γ-amine Propyltriethoxydecane or any combination of the above.

In one embodiment of the invention, the epoxy decane coupling agent (B2) comprises γ-propylene oxide propyl trimethoxy decane, γ-propylene oxide propyl triethoxy decane, γ-ring Oxypropanyl propyl methyl diethoxy decane or any combination of the above.

In one embodiment of the present invention, the fluorine-containing compound (C) comprises ammonium fluorozirconium, potassium fluorozirconium, fluorozirconic acid, ammonium fluorotitanate, fluorotitanic acid, fluoroantimonic acid, hydrofluoric acid, ammonium hydrofluoride or Any combination of the above.

In one embodiment of the present invention, the phosphoric acid compound (D) comprises a condensed phosphate of phosphoric acid, dihydrogen phosphate, monohydrogen phosphate, phosphate, tripolyphosphoric acid, tripolyphosphate or metaphosphoric acid; 1-hydroxyl Methane-1,1-diphosphonic acid, 1-hydroxyethane-1,1-diphosphonic acid, 1-hydroxypropane-1,1-diphosphonic acid, aminotrimethylenephosphonic acid, 2-phosphonic acid butane -1,2,4-tricarboxylic acid, a salt thereof or any combination thereof.

In one embodiment of the invention, the metal compound (E) is selected from at least one of the group consisting of compounds of aluminum, magnesium, manganese, and calcium.

In an embodiment of the invention, the water-dispersible resin (F) comprises a polyurethane resin, an acrylic resin or a combination thereof.

In an embodiment of the invention, the aqueous composition has a pH of from 6 to 11.

In order to achieve the above object, the present invention provides a method for surface treatment of a galvanized steel sheet, comprising: forming the aqueous surface treatment composition on a surface of a galvanized steel sheet; and heating and drying the galvanized steel sheet to A protective film is formed on the surface of the galvanized steel sheet, wherein the temperature of the drying and heating step may be from 70 ° C to 200 ° C.

In an embodiment of the present invention, before the step of forming the aqueous composition on the surface of the galvanized steel sheet, the surface of the galvanized steel sheet is further subjected to a cleaning step and a degreasing step.

In order to achieve the above object, the present invention provides a protective film formed on a surface of a galvanized steel sheet by a surface treatment method of a galvanized steel sheet as described above, wherein the protective film has a thickness of 0.6 μm to One thickness of 2 μm.

In order to achieve the above object, the present invention provides a surface-treated galvanized steel sheet comprising the protective film as described above and a galvanized steel sheet, wherein the protective film covers one surface of the galvanized steel sheet, and the protection The film has a thickness of one of 0.6 μm to 2 μm.

The aqueous composition for surface treatment, the surface treatment method, the protective film, and the surface-treated galvanized steel sheet of the present invention are applied, and the protective film thus formed and the protective layer are protected by the water-dispersible resin (F) having specific characteristics. The surface treated galvanized steel sheet of the film can achieve good corrosion resistance, alkali-resistant washing property, lubricity and excellent post-processing corrosion resistance.

Aqueous composition for metal surface treatment:

An object of the present invention is to provide an aqueous composition for metal surface treatment comprising a water-soluble zirconium compound (A), a decane coupling agent (B), a fluorine-containing compound (C), a phosphoric acid compound (D), and a metal. Compound (E) and water-dispersible resin (F). By the above-mentioned water-dispersible resin (F) having specific characteristics, the formed protective film and the surface-treated galvanized steel sheet containing the protective film can have corrosion resistance, alkali-resistant washing property, lubricity, and excellent post-processing corrosion resistance. Sex. The respective components of the aqueous composition for metal surface treatment of the present invention will be separately explained below.

Specifically, the pH of the aqueous composition of the present invention is, for example, 6 to 11. If the pH is less than 6, the aqueous composition is not easily dispersed uniformly to form a precipitate. On the other hand, if the pH is more than 11, the corrosion resistance of the formed protective film is not good.

In one example, the aqueous composition can be adjusted to the above pH range with an acid or lye depending on the pH of the aqueous composition being formulated. The above acid solution may be, for example, a hydrochloric acid solution or a nitric acid solution. The above lye may be, for example, a sodium hydroxide solution or a potassium hydroxide solution.

Water-soluble zirconium compound (A):

The water-soluble zirconium compound (A) referred to herein may include zirconium nitrate, zirconyl nitrate, zirconium sulfate, zirconium acetate, ammonium zirconium carbonate, sodium zirconium carbonate, potassium zirconium carbonate or any combination thereof.

When a protective film containing a water-soluble zirconium compound (A) is formed on a metal surface of a galvanized steel sheet, zirconium ions therein can effectively suppress the anode and cathode causing corrosion. The redox reaction can effectively increase the corrosion resistance of the galvanized steel sheet.

Decane coupling agent (B):

In one embodiment, the decane coupling agent (B) may be used in an amount of 50 parts by weight to 200 parts by weight based on 100 parts by weight of the water-soluble zirconium compound (A).

The decane coupling agent (B) referred to herein as the present invention can form a two-dimensional or three-dimensional crosslinked structure of neodymium (Si-O) bonds, and also forms a bismuth-oxygen-metal with the metal surface of the galvanized steel sheet (Si-OM). The key, in addition to providing a dense protective film of galvanized steel, can also increase the adhesion between the protective film and the galvanized steel.

When the amount of the above-mentioned decane coupling agent (B) used is less than 50 parts by weight, the corrosion resistance and alkali-resistant property of the formed protective film and the adhesion of the protective film to the galvanized steel sheet and/or other coating layer are not good. On the other hand, if the above-mentioned decane coupling agent (B) is used in an amount of more than 200 parts by weight, it is not advantageous for improving the properties of the protective film, but causes an increase in manufacturing cost, and more preferably lowers the drying property of the protective film.

The decane coupling agent (B) may comprise an amino decane coupling agent (B1) and an epoxy decane coupling agent (B2). The weight ratio of the amino decane coupling agent (B1) to the epoxy decane coupling agent (B2) may be from 0.3 to 1.2. The amino decane coupling agent (B1) and the epoxy decane coupling agent (B2) are separately described below.

Amino decane coupling agent (B1):

In one embodiment, the amino decane coupling agent (B1) may comprise γ-aminopropyltrimethoxydecane, γ-aminopropyltriethoxydecane, N-β(aminoethyl)-γ -Aminopropylmethyldiethoxydecane, N-β(aminoethyl)-γ-aminopropyltrimethoxydecane, N-β(aminoethyl)-γ-aminopropyl Triethoxydecane or any combination of the above.

Epoxy decane coupling agent (B2):

In one embodiment, the epoxy decane coupling agent (B2) may comprise γ-propylene oxide propyl trimethoxy decane, γ- propylene oxide propyl triethoxy decane, γ- propylene oxide group. Propylmethyldiethoxydecane or any combination of the above.

The aforementioned amino decane coupling agent (B1) and epoxy decane coupling agent (B2) can respectively provide an organic amine group and an epoxy group, when the aqueous composition of the present invention is used for the metal of a galvanized steel sheet. When the surface forms a protective film, the above-mentioned amine group and epoxy group can increase the adhesion of the protective film to other coating layers.

In one example, the other coating described above may be, for example, a pigment coating, in which case the protective film formed using the aqueous composition of the present invention has good paintability. The above-mentioned pigment coating layer can be, for example, an acrylic resin of the grammar type manufactured by Kansai Paint or an alkyd resin of the Yamera 1000 type.

The use of the above specific ratio (weight ratio of 0.3 to 1.2) of the amino decane coupling agent (B1) and the epoxy decane coupling agent (B2) can increase the protective film formed by the aqueous composition and other coatings (especially It is the adhesion of a coating containing an organic functional group.

If the above decane coupling agent (B) does not contain an organic functional group such as an amino group of the amino decane coupling agent (B1) or an epoxy group of the epoxy decane coupling agent (B2), the reinforced group is further strengthened. Adhesion of the formed protective film to other coatings, particularly coatings containing organic functional groups. Further, if the weight ratio of the amino decane coupling agent (B1) and the epoxy decane coupling agent (B2) is less than 0.3 or more than 1.2, the adhesion of the formed protective film to the pigment coating layer cannot be enhanced (i.e., Lacquerability cannot be strengthened).

In short, if the decane coupling agent (B) of the present invention has both an organic functional group (epoxy group and amine group) and an inorganic functional group (decyloxy group), it can contribute to strengthening the formed protective film. Adhesion to metal surfaces and other coatings of galvanized steel sheets.

Fluorine-containing compound (C):

The fluorine-containing compound (C) may have at least one fluoride ion group. Specifically, the fluorine-containing compound (C) may include ammonium fluorozirconium, potassium fluorozirconate, fluorozirconic acid, ammonium fluorotitanate, fluorotitanic acid, fluoroantimonic acid, hydrofluoric acid, ammonium hydrofluoride or any combination thereof. .

In one embodiment, the fluorine-containing compound (C) may be used in an amount of 20 parts by weight to 100 parts by weight based on 100 parts by weight of the water-soluble zirconium compound (A).

When the amount of the above fluorine-containing compound (C) used is less than 20 parts by weight, the alkali-resistant washing property of the protective film formed of the aqueous composition is not good. On the other hand, when the amount of the fluorine-containing compound (C) used is more than 100 parts by weight, the blackening resistance of the protective film formed using the aqueous composition of the present invention is not good. Further, the fluorine-containing compound (C) of the present invention can also enhance the adhesion of the formed protective film to the metal surface of the galvanized steel sheet.

Phosphoric acid compound (D):

The phosphoric acid compound (D) may comprise a condensed phosphate of phosphoric acid, dihydrogen phosphate, monohydrogen phosphate, phosphate, tripolyphosphoric acid, tripolyphosphate or metaphosphoric acid; 1-hydroxymethane-1,1-diphosphonic acid , 1-hydroxyethane-1,1-diphosphonic acid, 1-hydroxypropane-1,1-diphosphonic acid, aminotrimethylenephosphonic acid, 2-phosphonic acid butane-1,2,4-tricarboxylate An acid, a salt thereof or any combination of the above. In one example, the dihydrogen phosphate salt can be, for example, dihydrogen phosphate.

In one embodiment, the phosphoric acid compound (D) may be used in an amount of 20 parts by weight to 70 parts by weight based on 100 parts by weight of the water-soluble zirconium compound (A).

When the amount of the phosphoric acid compound (D) used is less than 20 parts by weight, the protective film formed using the aqueous composition of the present invention has poor adhesion to the metal surface and the corrosion resistance provided by the protective film is insufficient. On the other hand, when the amount of the phosphoric acid compound (D) used is more than 70 parts by weight, the metal surface is excessively activated to lower the alkali-resistant property of the protective film. Further, the phosphoric acid compound (D) of the present invention can also enhance the adhesion of the formed protective film to the metal surface of the galvanized steel sheet.

Metal compound (E):

The metal compound (E) may be selected from at least one of a group consisting of compounds of aluminum, magnesium, manganese, and calcium. In a specific example, the metal compound (E) may be, for example, aluminum sulfate, aluminum nitrate, aluminum acetate, aluminum oxide, aluminum dihydrogen phosphate, magnesium sulfate, magnesium nitrate, magnesium acetate, magnesium oxalate, magnesium oxide, manganese sulfate, nitric acid. Manganese, manganese acetate, manganese oxide, calcium sulfate, calcium nitrate, calcium acetate, calcium oxide or any combination of the above.

In one embodiment, the metal compound (E) may be used in an amount of 20 parts by weight to 60 parts by weight based on 100 parts by weight of the water-soluble zirconium compound (A).

The metal compound (E) referred to in the present invention is present in an ionic form, and when it is in contact with the metal surface of the galvanized steel sheet, it may be substituted or precipitated on the metal surface to further improve the effect of the metal surface. It inhibits the blackening of the metal surface of galvanized steel sheets.

When the amount of the metal compound (E) used is less than 20 parts by weight, the blackening resistance of the formed protective film is not good. On the other hand, when the amount of the metal compound (E) used is more than 60 parts by weight, the corrosion resistance of the protective film is not good.

Water-dispersible resin (F):

The water-dispersible resin (F) referred to herein as a general property can improve the barrier effect of the formed protective film and further suppress the blackening phenomenon of the metal surface of the galvanized steel sheet. Further, the use of the water-dispersible resin (F) in a specific use amount range can increase the alkali resistance, chemical resistance, and solvent resistance of the formed protective film.

However, it is worth mentioning that, based on one of the objects to be achieved by the present invention, the water-dispersible resin (F) in the embodiment of the present invention has specific properties to improve the post-process corrosion resistance of the formed protective film, the specific property. The method comprises a weight average molecular weight of more than 60,000, and an elongation at break of the water-dispersible resin (F) is between 50% and 150%. If the weight average molecular weight is less than 60,000, the corrosion resistance after processing is insufficient. In addition, if the elongation at break is less than 50%, the ductility of the formed protective film is insufficient to make the corrosion resistance after processing poor; if the elongation at break is higher than 150%, the corrosion resistance and resistance of the formed protective film are improved. Insufficient alkali washability.

In another aspect, the specific property further comprises a multiple glass transition temperature (Tg) of a particular temperature region having at least one low temperature region and at least one high temperature region, the temperature region of the low temperature region being between -20 and 25 ° C, The temperature range of the high temperature zone is between 50 and 90 °C. If the water-dispersible resin (F) has the characteristics of the low temperature region, the ductility of the formed protective film can be enhanced, so that the corrosion resistance after processing can be improved, and if the water-dispersible resin (F) has the high temperature region The characteristics can increase the corrosion resistance and alkali washing resistance of the formed protective film.

In one embodiment, the water-dispersible resin (F) has an average particle diameter of between 0.05 and 0.3 μm. In another embodiment, the water-dispersible resin (F) is, for example, a package A resin containing a functional group soluble in water or dispersed in water. In one example, the water-dispersible resin (F) comprises a polyurethane resin, an acrylic resin, or a combination thereof. The following are separately analyzed.

In one embodiment, the polyurethane resin may be a resin obtained by reacting a polyol such as a polyester polyol or a polyether polyol with a diisocyanate, which is water-dispersible or water-soluble.

In another embodiment, the acryl resin described above may be synthesized from acrylic acid, methacrylic acid, acrylate, methacrylate or a combination of any of the foregoing. Further, the above acrylic resin may comprise an acrylic graft epoxy copolymer, an acrylic graft polyurea resin interpolymer, an acrylic graft polyolefin resin interpolymer or any combination thereof.

In one embodiment, the water-dispersible resin (F) is used in an amount of 70 parts by weight to 90 parts by weight based on 100 parts by weight of the total solid content of the aqueous composition. The term "total solid content" as used herein means water-soluble zirconium compound (A), decane coupling agent (B), fluorine-containing compound (C), phosphoric acid compound (D), metal compound (E), water-dispersible resin ( F) and the sum of the amounts of emulsifying wax (G) to be described later.

When the amount of the aqueous dispersion resin (F) used is less than 70 parts by weight, the formed protective film is inferior in alkali resistance, chemical resistance, and solvent resistance. On the other hand, when the amount of the aqueous dispersion resin (F) used is more than 90 parts by weight, the corrosion resistance of the formed protective film is not good.

Emulsifying wax (G):

The aqueous composition of the present invention may further comprise an emulsifying wax (G) which may be used to increase the lubricity of the galvanized steel sheet. In one embodiment, the emulsifying wax (G) comprises a low molecular weight ethylene wax, a polyolefin wax, a polyethylene modified aqueous emulsifying wax, an aqueous polytetrafluoroethene (PTEE) emulsifying wax, or a combination thereof. And the emulsifying wax (G) may have a melting point of more than 100 °C.

In one example, the polyolefin wax described above can be, for example, a homopolymer and a copolymer synthesized from ethylene, propylene, and other alpha-olefins.

In one example, the above polyethylene modified aqueous emulsifying wax can be, for example It is an oxidized polyethylene wax/paraffin mixture, an oxidized polyethylene wax, a high density oxidized polyethylene wax, a high density polyethylene emulsion wax or any combination thereof.

In one embodiment, the emulsifying wax may be used in an amount of 5 parts by weight to 10 parts by weight based on 100 parts by weight of the total solid content of the aqueous composition.

When the amount of the above-mentioned emulsifying wax (G) is less than 5 parts by weight, the lubricity of the formed protective film is insufficient. On the other hand, if the emulsifying wax (G) is used in an amount of more than 10 parts by weight, the corrosion resistance of the formed protective film is insufficient.

Preparation of aqueous compositions for metal surface treatment:

The water-soluble zirconium compound (A), the decane coupling agent (B), the fluorine-containing compound (C), the phosphoric acid compound (D), the metal compound (E), and the water-dispersible resin (F) are mixed in the water in accordance with the aforementioned amounts. An aqueous composition can be obtained by selectively adding an emulsifying wax (G).

Form a protective film:

Another aspect of the present invention is to provide a surface treatment method. In one embodiment, the aqueous composition is formed on the surface of the galvanized steel sheet, and in an example, the content of the aqueous composition on the surface of the galvanized steel sheet is from 1 g/m ² to 1.5 g/m ² . Next, the galvanized steel sheet described above is subjected to a heat drying step to form a protective film on the galvanized steel sheet. In an example, the temperature of the aforementioned heat drying step may be from 70 ° C to 200 ° C.

In another embodiment, the galvanized steel sheet may be subjected to a washing step and a degreasing step before the step of forming the aqueous composition on the surface of the galvanized steel sheet.

In an example, the protective film may have a film thickness of 0.6 μm to 2 μm, and preferably, the film thickness may be 0.7 μm to 1.5 μm. If the film thickness of the above protective film is less than 0.6 μm, the corrosion resistance is not good. On the other hand, if the film thickness of the protective film is more than 2 μm, the appearance thereof is liable to be uneven and the manufacturing cost is increased.

The protective film of the present invention belongs to an organic-inorganic composite protective film which utilizes the aqueous composition to suppress the redox reaction of the anode and the cathode, wherein the water-soluble zirconium compound (A) is infiltrated with the decane coupling agent (B). Between the linked structures, after the heating and drying step, the decane coupling agent (B) is adsorbed and/or crosslinked with the water-soluble zirconium compound (A). Join to form a skeleton of the protective film. Further, since the aqueous composition contains the water-dispersible resin (F), when the aqueous composition is dried, an organic-inorganic composite protective film which is hardly soluble in water can be formed with the inorganic skeleton described above to increase corrosion resistance.

On the other hand, when the fluorine-containing compound (C) and the phosphoric acid compound (D) in the aqueous composition are in contact with the metal surface, the reactivity of the treatment agent with the metal surface can be enhanced, and the adhesion between the protective film/metal interface can be enhanced, which is remarkable. Improve the shortcomings of the subsequent processing process to damage the main body of the protective film and affect the performance of the product.

Further, the water-dispersible resin (F) in the aqueous composition has a specific property and contains a specific range of weight. a molecular weight and elongation at break (ε _B ), and optionally a multiple glass transition temperature (Tg) having a specific temperature region having at least one low temperature region and at least one high temperature region having a temperature range of -20 Between 25 ° C, the temperature range of the high temperature zone is between 50 and 90 ° C. The specific properties described above can enhance the various effects of the formed protective film, which have been described in detail in the above paragraphs and will not be described again.

Therefore, the aqueous composition, the surface treatment method, the protective film and the surface-treated galvanized steel sheet for metal surface treatment of the invention can effectively block the invasion of the corrosion factor, and at the same time, the surface of the metal material has good corrosion resistance and alkali-resistant washing. Sex, and the formed protective film has good post-processing corrosion resistance.

The following description of several embodiments and comparative examples demonstrates that the present invention can achieve the above-described effects.

Example 1:

100 parts by weight of ammonium zirconium carbonate, 18.5 parts by weight of γ-aminopropyltrimethoxydecane, 61.5 parts by weight of γ-epoxypropanepropyltrimethoxydecane, 50 parts by weight of fluorozirconic acid, 30 parts by weight of dihydrogen phosphate, 20 parts by weight of aluminum nitrate, and 80 parts by weight of the polyurethane resin (F-1) and 8 parts by weight based on 100 parts by weight of the total solid content of the obtained aqueous composition The high density polyethylene emulsifying wax was uniformly mixed in deionized water to form the aqueous composition of Example 1, which had a solid content of about 15 to 16% by weight. The polyurethane resin (F-1) used in Example 1 has a specific property, and its average molecular weight is about 160,000, and the glass transition temperature is low. The temperature zone is 0 to 6 ° C and the high temperature zone is 58 to 62 ° C, and the elongation at break is about 80%.

Next, the hot dip galvanized steel sheet is subjected to alkali degreasing treatment, water washing, and drying to clean the metal surface of the hot dip galvanized steel sheet. Then, the above aqueous composition was applied to the metal surface of the hot dip galvanized steel sheet by a bar coater (RDS No. 3), and the hot dip galvanized steel sheet coated with the aqueous composition was placed in a heat cycle type oven. The film was dried at a plate temperature of 100 ° C and dried for a while to form a protective film. The protective film formed has a weight of about 0.9 to 1.0 g/m ² .

Examples 2 to 8 and Comparative Examples 1 to 6

Examples 2 to 8 and Comparative Examples 1 to 6 were carried out using the same process method as in Example 1. The difference between Examples 2 to 8 and Comparative Examples 1 to 6 was to change the amount and/or type of each component of the aqueous composition used. The specific process conditions and evaluation results of Examples 2 to 8 and Comparative Examples 1 to 6 are shown in Table 1 below and Table 2 below, and therefore will not be further described herein.

A-1 ammonium zirconium carbonate

A-2 zirconyl nitrate

B-1-1 γ-aminopropyltrimethoxydecane

B-1-2 N-β(aminoethyl)-γ-aminopropyltriethoxydecane

B-2-1 γ-propylene oxide propyl trimethoxy decane

C-1 fluorozirconic acid

C-2 fluorotitanate

D-1 dihydrogen phosphate

D-2 1-hydroxymethane-1,1-diphosphonic acid

E-1 aluminum nitrate

E-2 aluminum dihydrogen phosphate

F-1 polyurethane resin (weight average molecular weight 160,000, elongation at break 80%, glass conversion) Temperature low temperature zone 0~6°C, high temperature zone 58~62°C)

F-2 polyurethane resin (weight average molecular weight 25000, elongation at break 24%, glass conversion) Temperature low temperature zone -6~3°C, high temperature zone 68~78°C)

F-3 acrylic resin (weight average molecular weight 280,000, elongation at break 105%, glass conversion) Temperature low temperature zone 8~13°C, high temperature zone 70~72°C)

F-4 acrylic resin (weight average molecular weight 220,000, elongation at break 35%, glass conversion) Temperature high temperature zone 57~61 °C, no low temperature zone)

G-1 high density polyethylene emulsifying wax

G-2 water-based Teflon emulsifying wax

G-3 75wt% G-1+25wt% G-2

Evaluation method:

Corrosion resistance

The corrosion resistance referred to herein is carried out by a salt spray test in accordance with JIS Z-2371 standard method, wherein the test is carried out for 72 hours. The rust area generated by the hot dip galvanized steel sheets of Examples 1 to 8 and Comparative Examples 1 to 6 was visually evaluated, and the smaller the rusted area, the better the corrosion resistance. In the example of the invention, the rusted area may have a white, off-white or other similar color. The relevant evaluation criteria are as follows:

◎: rust area <5%

○: 5% rusted area ≦ 10%

△: 10% < rust area ≦ 40%

×: The rust area is >40%.

2. Alkali resistance

The alkali-resistant washing property referred to herein is the immersion of the hot-dip galvanized steel sheets of Examples 1 to 8 and Comparative Examples 1 to 6 in a 65 ° C alkali-eluting grease (Parclean 364S (20 g/L); Baka, Japan) Lai company made) 2 minutes. Thereafter, the hot dip galvanized steel sheet was subjected to water cooling and cold air blowing. Next, the hot dip galvanized steel sheet was subjected to the above-described evaluation method of corrosion resistance (JIS Z-2271 standard method), and the white rust area generated by the hot dip galvanized steel sheet was visually evaluated. The smaller the rusted area, the better the alkali-resistant washing property. In the example of the invention, the rusted area may have a white, off-white or other similar color. The relevant evaluation criteria are as follows:

◎: rust area <5%

○: 5% rusted area ≦ 10%

△: 10% < rust area ≦ 40%

×: The rust area is >40%.

3. Lubricity

The lubricity referred to herein as "Bowden Test" was carried out under the following conditions: a load of 200 g, a speed of 5 cm/sec, and a test temperature of 25 °C. The evaluation results are expressed by the coefficient of friction, and the lower the coefficient of friction, the better the lubricity. The relevant evaluation criteria are as follows:

◎: friction coefficient <0.2

○: 0.2≦ friction coefficient <0.3

×: friction coefficient 0.3.

4. Processing corrosion resistance

The corrosion resistance (or post-process corrosion resistance) referred to herein as the hot-dip galvanized steel sheets of Examples 1 to 8 and Comparative Examples 1 to 6 was topped by a surface testing machine (Erichsen model 202; manufactured by Erichsen, Germany). 8 mm in height, and the evaluation method of the corrosion resistance as described above (JIS Z-2371 standard method) was carried out, and the rust generated in the top portion of the hot dip galvanized steel sheets of Examples 1 to 8 and Comparative Examples 1 to 6 was visually evaluated. The smaller the rusted area, the better the corrosion resistance. In the example of the present invention, The rusted area described above may have a white, off-white or other similar color. The relevant evaluation criteria are as follows:

◎: rust area <1%

○: 1% rusted area ≦ 10%

△: 10% < rust area ≦ 50%

×: The rust area is >50%.

According to the evaluation results of Tables 1 and 2, Examples 1 to 8 of the present invention achieve the above effects by a plurality of compositions having a specific content, that is, do not substantially affect the corrosion resistance and alkali resistance of the formed protective film. Under the premise of the washing effect (in some cases, it is also possible to improve the corrosion resistance and the alkali-washing resistance), the corrosion resistance of the protective film after processing can be improved. More specifically, the effect of improving the corrosion resistance after the processing is at least achieved by the water-dispersible resin (F) having a specific property, which has been described in detail in the above paragraph, and therefore will not be described again. On the other hand, a specific amount of emulsifying wax (100 parts by weight based on the total solid content and 5 parts by weight or more of the emulsifying wax) may be added to impart a good lubricity to the formed protective film.

While the invention has been described above in terms of several embodiments, it is not intended to limit the scope of the invention, and the invention may be practiced in various embodiments without departing from the spirit and scope of the invention. The scope of protection of the present invention is defined by the scope of the appended claims.

Claims (14)

An aqueous composition for metal surface treatment comprising: a water-soluble zirconium compound (A); a decane coupling agent (B); a fluorine-containing compound (C); a phosphoric acid compound (D); a metal compound (E); The water-dispersible resin (F) comprising a polyurethane resin, an acrylic resin or a combination thereof, wherein the water-dispersible resin (F) has a weight average molecular weight of more than 60,000, and the elongation at break of the water-dispersible resin (F) is Between 50% and 150%, and the water-dispersible resin (F) has a glass transition temperature of at least two temperature zones, the at least two temperature zones comprising at least one low temperature zone between -20 and 25 ° C and At least one high temperature zone between 50 and 90 ° C, wherein the decane coupling agent (B) is used in an amount of 50 parts by weight to 200 parts by weight based on 100 parts by weight of the water-soluble zirconium compound (A). The fluorine-containing compound (C) is used in an amount of 20 parts by weight to 100 parts by weight, the phosphoric acid compound (D) is used in an amount of 20 parts by weight to 70 parts by weight, and the metal compound (E) is used in an amount of 20 parts by weight. To 60 parts by weight, based on 100% by weight of the total solid content of the aqueous composition, the water is dispersed The amount of resin (F) of 90 to 70 parts by weight to parts by weight. The aqueous composition for metal surface treatment according to claim 1, further comprising an emulsifying wax (G), wherein one of the emulsifying wax (G) is used based on the total solid content of 100 parts by weight. It is 5 parts by weight to 10 parts by weight. The aqueous composition for metal surface treatment according to claim 1, wherein the water-soluble zirconium compound (A) comprises zirconium nitrate, zirconyl nitrate, zirconium sulfate, zirconium acetate, ammonium chromium carbonate, sodium zirconium carbonate , potassium zirconium carbonate or any combination of the above. The aqueous composition for metal surface treatment according to claim 1, wherein the decane coupling agent (B) comprises an amino decane coupling agent (B1) and an epoxy decane coupling agent (B2), and the amine The weight ratio of one of the decane coupling agent (B1) to the epoxy decane coupling agent (B2) is from 0.3 to 1.2. An aqueous composition for metal surface treatment according to claim 4, wherein the amino decane coupling agent (B1) comprises γ-aminopropyltrimethoxydecane, γ-aminopropyltriethyl Oxydecane, N-β(aminoethyl)-γ-aminopropylmethyldiethoxydecane, N-β(aminoethyl)-γ-aminopropyltrimethoxydecane, N -β(aminoethyl)-γ-aminopropyltriethoxydecane or any combination of the above. An aqueous composition for metal surface treatment according to claim 4, wherein the epoxy decane coupling agent (B2) comprises γ-propylene oxide propyl trimethoxy decane, γ-propylene oxide Propyltriethoxydecane, gamma-propylene oxide propylmethyldiethoxydecane or any combination of the above. The aqueous composition for metal surface treatment according to claim 1, wherein the fluorine-containing compound (C) comprises ammonium fluorozirconium, potassium fluorozirconium, fluorozirconic acid, ammonium fluorotitanate, fluorotitanate, and fluorine. Niobic acid, hydrofluoric acid, ammonium hydrofluoride or any combination of the above. An aqueous composition for metal surface treatment according to claim 1, wherein the phosphate compound (D) comprises phosphoric acid, dihydrogen phosphate, phosphoric acid a condensed phosphate of monohydrogen salt, phosphate, tripolyphosphoric acid, tripolyphosphate or metaphosphoric acid; 1-hydroxymethane-1,1-diphosphonic acid, 1-hydroxyethane-1,1-diphosphonic acid, 1-Hydroxypropane-1,1-diphosphonic acid, aminotrimethylenephosphonic acid, 2-phosphonic acid butane-1,2,4-tricarboxylic acid, a salt thereof or any combination thereof. The aqueous composition for metal surface treatment according to claim 1, wherein the metal compound (E) is selected from at least one of a group consisting of a compound of aluminum, magnesium, manganese, and calcium. . An aqueous composition for metal surface treatment as described in claim 1, which has a pH of from 6 to 11. A galvanized steel sheet surface treatment method comprising: forming an aqueous composition for metal surface treatment according to any one of claims 1 to 10 on a surface of a galvanized steel sheet; and galvanizing the galvanized steel sheet The steel sheet is subjected to a heat drying step to form a protective film on the surface, wherein the heat drying step is carried out at a temperature of from 70 ° C to 200 ° C. The method for treating a surface of a galvanized steel sheet according to claim 11, wherein the step of forming the aqueous composition on the surface of the galvanized steel sheet further comprises: performing a cleaning step on the surface of the galvanized steel sheet; A degreasing step. A protective film formed on a surface of a galvanized steel sheet by a surface treatment method of a galvanized steel sheet according to any one of claims 11 to 12, wherein the protective film has a thickness of 0.6 μm to One thickness of 2 μm. A surface-treated galvanized steel sheet comprising the thirteenth item of the patent application scope The protective film and a galvanized steel sheet, wherein the protective film covers one surface of the galvanized steel sheet, and the protective film has a thickness of one of 0.6 μm to 2 μm.