TWI391529B - Metal surface treatment agent and its use - Google Patents

Description

Metal surface treatment agent and use thereof

The present invention relates to a metal surface treatment agent and its use, and in particular to a chromium-free metal surface treatment agent, a surface treatment method of a metal material using the metal surface treatment agent.

Plated steel plates (such as galvanized steel sheets) have good corrosion resistance, easy molding, welding and painting, and are widely used in home appliances, electronic products, machinery and construction industries. However, after a period of use, the galvanized layer of the galvanized steel sheet is corroded in the air (especially in a high-humidity heat environment) to form white rust, so the steel sheet needs to be passivated after galvanizing. It is customary to use chromate for passivation treatment, but as environmental issues have gradually gained great attention among various industries, and the European Union has banned the use of hexavalent chromium as a hazardous substance in 2002, the current treatment of steel sheet surface Most have been carried out towards chrome-free passivation.

TW 506996 discloses a metal surface treatment agent comprising (A) a vanadium compound and (B) a metal compound containing at least one metal selected from the group consisting of zirconium, titanium, molybdenum, tungsten, manganese or cerium. In the examples of this patent, in addition to the above (A) and (B), an etchant (HF, H ₂ ZrF ₆ , CH ₃ COOH, H ₂ SiF ₆ ) is added and the vanadium-containing compound is mainly used + The five-valent vanadium compound made some examples show that 10 to 30% of the area of white rust occurred after 48 hours of the corrosion resistance test, and it is apparent that the treatment agent of this patent is still unable to effectively improve the corrosion resistance. In addition, the treatment agent of this patent requires a relatively complicated procedure in preparation, and the solubility and stability in the treatment agent are still degraded.

According to the above, if the surface treatment agent of the metal material can be improved to improve the corrosion resistance, adhesion, high temperature resistance and the like of the surface of the metal material, it will be advantageous to solve the problems in the current industry, and at the same time, the metal material can be expanded. application.

Accordingly, it is an object of the present invention to provide a metal surface treatment agent which is chrome-free, has good corrosion resistance, adhesion and high temperature resistance to the surface of a metal material, and is easy to prepare.

Another object of the present invention is to provide a surface treatment method of a metal material using the above metal surface treatment agent.

It is still another object of the present invention to provide a surface treated metal material using the above surface treatment method.

Thus, the metal surface treatment agent of the present invention comprises an organic vanadium compound and a phosphorus-containing inorganic acid, wherein the vanadium ion of the organic vanadium compound has an oxidation number of +5.

The surface treatment method of the metal material of the present invention comprises the step of applying the above metal surface treatment agent to the surface of a metal material.

The surface-treated metal material of the present invention comprises a metal material body and a protective film formed on the metal material body, the protective film being made of the above metal surface treatment agent.

The corrosion process of metal materials (such as galvanized steel sheets) is caused by the infiltration of corrosion factors (oxygen, water, chloride ions, etc.) on the metal surface, which induces the electrochemical redox reaction, that is, in the cathode reaction, oxygen, Water or the like obtains electrons and generates OH ^- , which increases the concentration of OH ^- , and the anode reaction forms zinc ions due to the loss of electrons by the metal zinc. Therefore, in order to improve the corrosion resistance of the galvanized steel sheet, it is considered to focus on suppressing the redox reaction of the anode and the cathode. In the present invention, the method for suppressing the redox reaction of the anode and the cathode is to apply a metal surface treatment agent containing an organic vanadium compound and a phosphorus-containing inorganic acid to the surface of the metal, and then dried by heating, in the organic vanadium compound. The vanadium ion will be converted into vanadium oxide (the oxide formed by the vanadium ion is better than the +5 valence vanadium ion), and the ligand in the organic vanadium compound will be combined with the metal material. The metal ions generate a chelate reaction to form an insoluble and stable organometallic chelate on the surface of the metal material, thereby effectively preventing the intrusion of corrosion factors; the inorganic acid containing phosphorus can activate the surface of the metal material to enhance the surface and protection of the metal material. Adhesion between the membranes and formation of a stable vanadium-phosphorus composite oxide with vanadium ions of a portion of the organic vanadium compound. Therefore, the treatment of the metal surface treatment agent of the present 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 high temperature resistance, and the formed protective film and the surface of the metal material are also Will have good adhesion.

Preferably, the vanadium ion-containing organovanadium compound is an organovanadium compound having at least one ligand selected from a hydroxyl group, a carbonyl group, a carboxyl group, an ethyl decyl acetate or a combination thereof. More preferably, the vanadium ion-containing organovanadium compound is selected from the group consisting of VO(C ₅ H ₇ O ₂ ) ₂ , V(C ₅ H ₇ O ₂ ) ₃ or a combination thereof.

Preferably, the vanadium ion-containing organic vanadium compound is used in an amount ranging from 5 to 20 g/L, based on the volume of the metal surface treatment agent being 1 liter. When the content of the organic vanadium compound is less than 5 g/L, although a protective film can be formed, the corrosion resistance of the protective film is not good; when the content is higher than 20 g/L, the solubility of the metal surface treating agent is caused. Poor condition and precipitation.

Preferably, the phosphorus-containing inorganic acid is selected from the group consisting of phosphoric acid, polyphosphoric acid, metaphosphoric acid or a combination thereof.

Preferably, the phosphorus-containing inorganic acid is used in an amount ranging from 10 to 30 g/L, based on the volume of the metal surface treatment agent being 1 liter. When the content of the inorganic acid containing phosphorus is less than 10 g/L, the solubility of the metal surface treatment agent is poor, and the adhesion between the formed protective film and the surface of the metal material is more affected; when the content is higher than 30 g/ When L is used, the surface of the metal material is excessively activated to affect the formed protective film and corrosion resistance.

Preferably, the metal surface treatment agent further comprises a decane coupling agent. After hydrolysis and condensation, the decane coupling agent will form a chemical bond with Si-OM (M represents metal) on the surface of the metal material, so that the protective film has good adhesion to the surface of the metal material, and the overall structure of the protective film is more dense. .

The decane coupling agent may be any decane coupling agent for treating the surface of the metal material. Preferably, the decane coupling agent is selected from the group consisting of γ-aminopropyltrimethoxydecane and γ-aminopropyltriethoxylate. Base decane, γ-propylene oxide propyl trimethoxy decane, γ-propylene oxide propyl triethoxy decane, N-β (aminoethyl)-γ-aminopropyl methyl diethoxy Baseline, N-β(aminoethyl)-γ-aminopropyltrimethoxydecane, N-β(aminoethyl)-γ-aminopropyltriethoxydecane, γ-epoxy Propyl propyl methyl diethoxy decane or a combination of these.

Preferably, the volume of the metal surface treatment agent is 1 liter, and the amount of the decane coupling agent ranges from 4 to 20 g/L. When the amount of the decane coupling agent is less than 4 g/L, although a protective film is still formed on the surface of the metal material, the corrosion resistance and adhesion of the protective film are not good; when the amount of the decane coupling agent exceeds 20 g/L At the same time, the corrosion resistance and high temperature resistance of the protective film also become poor.

Preferably, the metal surface treatment agent has a pH range of 1.5 to 5.0. When the pH is lower than 1.5, the corrosion resistance of the protective film on the surface of the metal material is deteriorated to affect the surface appearance; and when the pH is higher than 5.0, the metal surface treatment agent is unstable and easily forms a precipitate. The metal surface treatment agent can adjust the pH value by a conventional means, for example, increasing or decreasing the amount of the phosphorus-containing inorganic acid as needed, or additionally adjusting it with an alkali solution.

The surface treatment method of the metal material of the present invention is completed by coating the above metal surface treatment agent on the surface of a metal material, and the coating method can adopt various known coating methods, and before coating, the metal The material can be cleaned and degreased first.

The surface treatment method of the present invention can be applied to the treatment of various metal materials. Preferably, the metal material is selected from the group consisting of aluminum, zinc, galvanized steel or galvanized aluminum.

Preferably, the surface treatment method further comprises a heat drying step. More preferably, the heat drying step has a temperature in the range of 50 ° C to 250 ° C.

Preferably, the protective film of the surface-treated metal material has a film thickness of 0.05 to 2 μm; more preferably, the film thickness of the protective film ranges from 0.1 to 1 μm. When the film thickness of the protective film is less than 0.05 μm, the corrosion resistance and adhesion of the protective film are not good. When the film thickness exceeds 2 μm, although the corrosion resistance can be effectively improved, the appearance is poor and the production cost is increased.

The protective film of the surface-treated metal material of the invention is mainly composed of inorganic materials, so that the metal material has good high temperature resistance, so it will be beneficial to the high temperature welding engineering.

The present invention will be further illustrated by the following examples, but it should be understood that this embodiment is intended to be illustrative only and not to be construed as limiting.

<Example> The common method of Embodiments 1 to 8 (hereinafter referred to as E1 to E8): 1. Metal surface treatment agent:

According to the amount and composition of the following Table 1, the organic vanadium compound, the phosphorus-containing inorganic acid and the selectively added decane coupling agent are respectively mixed, and then water is added until the total volume is 1 liter, which can be separately prepared. Metal surface treatment agents of Examples 1-8.

2. Surface treated metal materials:

A metal material (hot dip galvanized steel sheet, GI) was taken separately, and the surface was subjected to alkali degreasing treatment, water washing and drying, and then the surface of the metal obtained by the above was treated with a #3 bar coater (RDS No. 3). The agent is coated on the surface of the metal material, and the coated metal material is placed in a hot ring type oven, and dried at a plate temperature of 80 ° C or 100 ° C, respectively, and dried for a period of time, that is, respectively, Examples 1 to 8 are prepared. Surface treated metal material.

The common method of Comparative Examples 1 to 4 (hereinafter referred to as C1 to C4): 1. Metal surface treatment agent:

The preparation process was the same as that of Examples 1 to 8 except that the composition and amount of the components were changed according to the following Table 1. Finally, the metal surface treatment agents of Comparative Examples 1 to 4 were separately prepared.

2. Surface treated metal materials:

Except for the metal surface treatment agents of Comparative Examples 1 to 4, respectively, the other preparation processes were the same as those of Examples 1 to 8, and finally the surface-treated metal materials of Comparative Examples 1 to 4 were respectively obtained.

[test]

The surface-treated steel sheets obtained in the above Examples 1 to 8 and Comparative Examples 1 to 4 were subjected to the following tests, and the results are shown in Table 1:

1. Corrosion resistance: The salt spray test using the standard method of JIS Z-2371 was carried out, and the area of white rust on the surface of the steel sheet was visually evaluated after 72 hours of the test, and the smaller the area where white rust occurred, the better the corrosion resistance. If the area of white rust is ≧50%, it is judged that the corrosion resistance is not good, and it is marked as “×”; if 30% ≦ white rust occurs in area ≦50%, it is judged that the corrosion resistance is poor, and it is marked as “△”; if 10% ≦ white rust When the occurrence area is ≦30%, it is judged that the corrosion resistance is acceptable, and it is marked as "○": If the white rust occurrence area is <10%, the corrosion resistance is judged to be good, and it is indicated as "◎".

2. Adhesion: On the surface of the surface-treated steel sheets prepared in Examples 1 to 8 and Comparative Examples 1 to 4, respectively, an acrylic paint and an alkyd resin coating were applied, followed by baking and drying. A test layer is additionally formed on the surface of the steel sheet. Then, the center of the test layer was respectively cut with a cutter to a width of 1 mm, and the adhesion peeling test was performed, that is, the adhesion of the protective film was evaluated by the number of the unpeeled chessboard. When the number of residues is 95 or more, it has good adhesion.

3. High temperature resistance: The surface-treated steel sheets obtained in Examples 1 to 8 and Comparative Examples 1 to 4 were allowed to stand in a high temperature environment (400 ° C) for 5 minutes, and then the appearance of the steel sheet surface was visually evaluated and evaluated. The criteria are as follows:

◎: The surface appearance of the steel sheet after the high temperature test is the same as that of the steel sheet surface which has not been subjected to the high temperature test.

○: The surface appearance of the steel sheet after the high temperature test is slightly different from the surface appearance of the steel sheet which has not been subjected to the high temperature test.

△: The surface appearance of the steel sheet after the high temperature test is significantly yellower or darker than the surface appearance of the steel sheet without the high temperature test.

×: The surface appearance of the steel plate after the high temperature test is significantly yellower or darker than the surface appearance of the steel plate without the high temperature test, and the surface of the steel plate has a clear crack path.

[result]

From the results of Table 1, it is understood that Examples 1 to 8 both have good corrosion resistance, adhesion, and high temperature resistance; and in Comparative Examples 1 to 4, the above advantages are not simultaneously provided.

When Example 3 was compared with Comparative Example 1, it was found that Example 3 had considerably excellent corrosion resistance, adhesion, and high temperature resistance, and the adhesion of Comparative Example 1 was remarkably inferior because Comparative Example 1 used VOSO ₄ does not have an organic ligand, so that it cannot form an organic metal chelate with a metal ion, so that the formed protective film does not have good adhesion to the surface of the metal material. When Example 4 was compared with Comparative Example 2, it was found that Comparative Example 2 was not added with an organic vanadium compound, so that corrosion resistance and adhesion were remarkably poor. When Comparative Example 3 was compared with Comparative Example 3, although Comparative Example 3 additionally added citric acid and a decane coupling agent, corrosion resistance, adhesion, and high temperature resistance were not good because no phosphoric acid was added. When Example 3 was compared with Comparative Example 4, it was found that Comparative Example 4 used a large amount of a decane coupling agent, but corrosion resistance, adhesion, and high temperature resistance were not good because the amount of the decane coupling agent was too high. Caused.

In summary, the metal surface treatment agent of the present invention can form a protective film on the surface of the metal material through the combination of the organic vanadium compound (the vanadium ion is not +5 valence) and the phosphoric acid. The metal material has good corrosion resistance, adhesion and high temperature resistance.

The above is only the preferred embodiment of the present invention, and the scope of the invention is not limited thereto, that is, the simple equivalent changes and modifications made by the scope of the invention and the description of the invention are All remain within the scope of the invention patent.

Claims (11)

A metal surface treatment agent is composed of the following compounds: an organic vanadium compound, wherein the vanadium ion of the organic vanadium compound has an oxidation number of not +5; a phosphorus-containing inorganic acid; and water. The metal surface treatment agent according to claim 1, wherein the organic vanadium compound is an organovanadium compound having at least one ligand selected from the group consisting of a hydroxyl group, a carbonyl group, a carboxyl group and an ethyl group. Acetate or a combination of these. The metal surface treatment agent according to claim 2, wherein the organic vanadium compound is selected from the group consisting of VO(C ₅ H ₇ O ₂ ) ₂ , V(C ₅ H ₇ O ₂ ) ₃ or the like. A combination. The metal surface treatment agent according to the first aspect of the invention, wherein the volume of the metal surface treatment agent is 1 liter, and the amount of the organic vanadium compound ranges from 5 to 20 g/L. The metal surface treatment agent according to claim 1, wherein the phosphorus-containing inorganic acid is selected from the group consisting of phosphoric acid, polyphosphoric acid, metaphosphoric acid or a combination thereof. The metal surface treatment agent according to claim 1, wherein the volume of the metal surface treatment agent is 1 liter, and the amount of the inorganic acid is 10 to 30 g/L. The metal surface treatment agent according to claim 1 of the patent application has a pH range of 1.5 to 5.0. A surface treatment method for a metal material, comprising the step of applying a metal surface treatment agent as described in claim 1 to a surface of a metal material. A surface treatment method for a metal material according to claim 8, wherein the metal material is selected from the group consisting of aluminum, zinc, galvanized steel, or galvanized aluminum alloy. The surface treatment method of the metal material according to claim 8 further comprises a heating and drying step, wherein the heating and drying step has a temperature ranging from 50 ° C to 250 ° C. A surface-treated metal material comprising a metal material body and a protective film formed on the metal material body, the protective film being made of a metal surface treatment agent as described in claim 1 .