WO2016091059A1 - Surface treating agent for hot-dip aluminum-zinc steel plate, and hot-dip aluminum-zinc steel plate and manufacturing method therefor - Google Patents

Abstract

A surface treating agent for a hot-dip aluminum-zinc steel plate. The surface treating agent has the following components in parts by mass: 45 to 85 parts of aqueous aliphatic polyurethane resin, 5 to 20 parts of an organic silicon compound, 3 to 15 parts of a carbodiimide compound emulsion; 1 to 5 parts, based on metallic elements, of a water soluble metal slat compound; 1 to 10 parts, based on zirconia, of a water soluble zirconium compound; 1 to 10 parts of water dispersive nanometer clay; and 1 to 15 parts of a fluorine-containing polymer lubrication additive. A steel pate coated with the surface treating agent has good corrosion resistance, tarnish resistance, and machinability.

Description

Surface treatment agent for hot-dip aluminum-zinc steel plate, hot-dip aluminum-zinc steel plate and manufacturing method thereof Technical field

The present invention relates to a surface treatment agent for steel sheets, and more particularly to a surface treatment agent for coated steel sheets. The invention also relates to a coated steel sheet and a method of manufacturing the same.

Background technique

Because of its good corrosion resistance, high heat reflectivity, heat resistance and decorative appearance, hot-dip aluminum-zinc steel sheets are widely used in various fields such as construction and home appliances, for example, light steel in the construction industry. Structural roof and wall, purlins, floor panels, guardrails, sound barriers and drainage devices, etc., for example, large electrical appliances backboards, electrical cabinet shells and home appliance chassis lights in the home appliance industry. Especially when the hot-dip aluminum-zinc plate is used as the outdoor parts of household appliances, the harsh outdoor service environment puts more stringent requirements on the hot-dip aluminum-zinc steel plate: for example, the steel plate surface needs to have excellent corrosion resistance to ensure the steel plate is in service. The process is not corroded; for example, the surface of the steel sheet is required to have good anti-staining properties to prevent the contaminants in the outdoor environment from easily adhering to the surface of the steel sheet. At the same time, hot-dip galvanized steel sheets for household electrical appliances also require continuous stamping, which in turn places higher demands on the processing properties of steel. In addition, the surface of the hot-dip aluminum-zinc plate must also have good lubricity and wear resistance, that is, the surface of the steel plate can be protected from rubbing or pruning after the stamping, so that it can provide good resistance for a long period of time. Corrosion performance.

The Chinese Patent Publication No. CN1247777A, published on March 22, 2000, entitled "Resin-Coated Aluminum-Zinc Alloy Coated Steel Material" discloses a resin-coated aluminum-zinc alloy coated steel material having Good formability, resistance to chromium solubility, corrosion resistance, alkali resistance and coatability, silane coupling agent having an amino group; chromium ion; at least selected from triols having 2 to 3 carbons and binary The alcohol of one of the alcohols is incorporated into an acrylic polymer resin emulsion containing a carboxyl group and a glycidyl group and having an acid value of from 10 to 60, and the resulting mixture has a pH of from 7 to 9 to obtain a chromium-containing resin composition. The chromium-containing resin composition is applied to a substrate to form an application film, and dried to obtain a resin film. The silane coupling agent is used in an amount of from 0.5 to 3.0% by weight based on the resin solid content of the acrylic resin emulsion. The amount of the alcohol used is 25 to 150 wt.% of the chromium ion (B). The amount of the resin film is from 0.5 to 3.0 g/m ² . The content of chromium ions (B) in the resin film is 5 to 50 mg/m ² . The resin composition disclosed in this patent document is a chromium-containing product which does not have good environmental performance and is not suitable for use in the home appliance industry.

The publication number is CN1530462A, and the publication date is September 22, 2004. The Chinese patent document entitled "Metallic material surface treatment agent, aluminum alloy and lead-based alloy steel sheet treated with the treatment agent" relates to a metal material. a surface treatment agent and an aluminum-plated/lead-based alloy steel sheet treated by the treatment agent, wherein the surface treatment agent comprises: (A) an aqueous resin having a carboxyl group and an acid amine combination; and (B) an aluminum Al, magnesium Mg One or more metal compounds are selected from the metal compounds of calcium Ca, zinc Zn, nickel Ni, cobalt Co, iron Fe, zirconium Zr, titanium Ti, vanadium V, tungsten W, manganese Mn and cerium Ce; C) a surface treatment agent for a metal material containing a silicon compound but not containing chromium; and a steel sheet coated with an aluminum-containing lead-based alloy surface-treated with the above treatment agent, containing the above-mentioned (A) component and (B) component and The coating layer of the component C) is a plated aluminum-lead-based alloy steel sheet having a surface-treated amount of at least 0.2 to 5.0 g/m ² and containing no chromium. The technical solution of the above patent document does not relate to the anti-staining property and the processability of the galvanized steel sheet.

Japanese Patent No. JP2007-321224A, published on December 13, 2007, entitled "Excellent Corrosion Resistance of Al-Zn Alloy Coated Steel Sheet Using Chromate-Free Surface Treatment and Its Manufacturing Method" The literature discloses a hot-dip aluminum-zinc plate with excellent corrosion resistance and water-tightness. The surface of the steel plate is covered with a chromium-free organic/inorganic composite protective film containing a silane-modified aqueous anionic resin and tetravalent. A vanadium compound and a composition of phosphoric acid or a compound thereof.

Summary of the invention

One of the objects of the present invention is to provide a surface treatment agent for hot-dip aluminum-zinc steel sheets, which has excellent corrosion resistance, excellent stain resistance and good processability after being coated with the surface treatment agent. In addition, the surface treatment agent of the present invention does not contain chromium and has good stability, and has good environmental protection benefits and economic benefits.

In order to achieve the above object, the present invention provides a surface treatment agent for hot-dip aluminum-zinc steel sheets, the mass parts of which are:

Aqueous aliphatic polyurethane resin: 45-85 parts;

Silicone compound: 5-20 parts;

Carbodiimide compound emulsion: 3-15 parts;

a water-soluble metal salt compound, the mass fraction of which is based on the metal element: 1-5 parts;

a water-soluble zirconium compound, the mass fraction of which is zirconia: 1-10 parts;

Water-dispersible nanoclay: 1-10 parts;

Fluoropolymer lubricant builder: 1-15 parts.

In the above technical solution, the aqueous aliphatic urethane resin is an aliphatic anionic water-based urethane resin based on a polyester polyol, which may be an aqueous solution or a water-dispersible type, and has a solid content of 30 to 40%. When the mass fraction of the aqueous aliphatic urethane resin is less than 45 parts, the weather resistance and corrosion resistance of the coating are both lowered; when the mass fraction of the component exceeds 85 parts, the alkali resistance of the coating changes. difference. Preferably, the mass fraction of the aqueous aliphatic urethane resin can be controlled to 55 to 70 parts.

In the technical solution, the mass fraction of the silicone-based compound is set to 5 to 20 parts because the adhesion and corrosion resistance of the coating layer are lowered if the mass fraction of the silicone-based compound is less than 5 parts; When the mass fraction of the silicon compound is more than 20 parts, the corrosion resistance of the coating layer is lowered, and the stability of the surface treatment agent is also deteriorated. Further, the mass fraction of the silicone-based compound may be set to 7 to 15 parts.

In the embodiment of the present invention, the carbodiimide compound emulsion is capable of reacting with a carboxyl group in the aqueous aliphatic urethane resin to increase the degree of crosslinking of the composite coating layer. If the mass fraction of the carbodiimide compound emulsion is less than 3 parts, the crosslinking effect of the carbodiimide compound emulsion on the aqueous aliphatic polyurethane resin is not significant, and the degree of crosslinking of the coating layer may result in corrosion resistance. If the mass fraction of the carbodiimide compound emulsion is more than 15 parts, the reaction between the carbodiimide compound emulsion and the aqueous aliphatic urethane resin is too strong, and gelation is likely to occur, thereby causing surface treatment agent The stability of the decline. In order to obtain a better technical effect, the mass fraction of the carbodiimide compound emulsion may be further controlled to 4 to 10 parts.

Here, it is to be noted that the carbodiimide in the carbodiimide compound emulsion has a solid content of 35 to 50%, and the carbodiimide has an equivalent weight of 380 to 590.

Further, the water-soluble metal salt compound is used in an amount of from 1 to 5 parts by mass based on the metal element contained therein. When the mass fraction of the total amount of the metal element contained in the water-soluble metal salt compound is less than 1 part, the coating has a poor anti-film expansion ability; when the water-soluble metal salt compound has a metal element When the mass fraction of the total amount is more than 5 parts, the metal ions have an influence on the stability of the surface treatment agent, resulting in a decrease in the stability of the surface treatment agent. Preferably, the mass fraction of the water-soluble metal salt compound is designed to be 2 to 4 parts.

According to the technical solution of the present invention, the water-soluble zirconium compound is added in parts by mass based on the zirconia. If the mass fraction of zirconia is less than 1 part, the UV aging resistance and adhesion of the coating will be poor; if the mass fraction of zirconia is more than 10 parts, the surface treatment agent will be stabilized. Sexual decline. Preferably, the mass fraction of the water-soluble zirconium compound can be designed to be 3 to 6 parts.

The present invention designs the mass fraction of the water-dispersible nanoclay in the surface treatment agent to be 1 to 10 parts because if the water-dispersed nanoclay has less than 1 part by mass, the corrosion resistance of the coating may be caused. And the reduction in stain resistance; if the mass fraction of the water-dispersible nanoclay exceeds 10 parts, the viscosity of the surface treatment agent is greatly increased, resulting in a decrease in workability and stability of the surface treatment agent. Preferably, the mass fraction of the water-dispersible nanoclay can be designed to be 2 to 6 parts.

The technical solution of the present invention controls the mass fraction of the fluoropolymer-based lubricating auxiliary agent to be 1 to 15 parts, because the coating amount is when the mass fraction of the fluoropolymer-based lubricating auxiliary agent is less than 1 part. Lubricity is not sufficient; when the mass fraction of the fluoropolymer-based lubricating agent is more than 15 parts, the corrosion resistance and weather resistance of the coating may be lowered. As a more preferable setting range, the mass fraction of the fluoropolymer-based lubricating auxiliary agent is controlled to be 3 to 10 parts.

Further, in the surface treatment agent for hot-dip galvannealed steel sheets according to the present invention, the silicone-based compound is at least one of silicic acid, silicate, colloidal silica, and an organosilane coupling agent.

Further, in the surface treatment agent for hot-dip galvannealed steel sheets according to the present invention, the organosilicon compound is an organosilane coupling agent, and the organosilane coupling agent is a vinyl silane coupling agent or a ring. At least one of an oxy-based silane coupling agent and a fluorenyl-based silane coupling agent.

Further, in the surface treatment agent for hot-dip galvannealed steel sheets according to the present invention, the water-soluble zirconium compound is zirconium carbonate.

Further, in the surface treatment agent for hot-dip galvannealed steel sheets according to the present invention, the water-dispersible nanoclay is at least one of nano montmorillonite, nano bentonite and polyphosphate-modified nanobentonite.

Taking polyphosphate-modified nanobentonite as an example, it can be evenly spread in the coating with nanosheets to significantly improve the corrosion resistance and stain resistance of the coating.

Further, in the surface treatment agent for hot-dip galvannealed steel sheets according to the present invention, the fluoropolymer-based lubricating auxiliary agent is a polytetrafluoroethylene wax and/or a polytetrafluoro wax.

Further, in the surface treatment agent for hot-dip galvannealed steel sheets according to the present invention, the fluoropolymer-based lubricating auxiliary agent has an average particle diameter of 0.1 to 2.0 μm.

The inventors have found that when the average particle diameter of the fluoropolymer-based lubricating agent is less than 0.1 μm or more than 2.0 μm, the processability of the composite coating layer is lowered. Therefore, in order to improve the processing properties of the steel sheet coated with the composite coating, it is preferred to use an average particle of the fluoropolymer-based lubricating agent. The diameter is limited to be in the range of 0.1 to 2.0 μm; more preferably, the average particle diameter of the fluoropolymer-based lubricating agent may be controlled to be between 0.3 and 1.0 μm.

Another object of the present invention is to provide a hot-dip aluminum-zinc steel sheet which has excellent corrosion resistance, excellent surface anti-staining property, and good processability. In addition, the hot-dip galvanized steel sheet coated with the surface treatment agent does not contain harmful chromium elements on its surface, and is an environmentally friendly product, and can be applied to related industries such as construction and home appliances.

In order to achieve the above object, the present invention provides a hot-dip aluminum-zinc steel sheet having a surface having a surface treatment agent-coated composite coating as mentioned above.

Further, the composite coating of the hot-dip galvanized steel sheet according to the present invention has a dry film thickness of from 1 to 3 μm.

If the dry film thickness of the composite coating is less than 1 micrometer, the composite coating applied to the surface of the steel sheet may be relatively thin, which may result in a decrease in the overall properties such as press formability, corrosion resistance, and stain resistance of the steel sheet.

Correspondingly, the present invention also discloses a method for manufacturing the above-mentioned hot-dip galvanized steel sheet, which comprises: directly coating a surface treatment agent on at least one surface of the hot-dip galvanized steel sheet, drying at 80 to 180 ° C, and obtaining a composite surface Coated hot-dip galvanized steel sheet.

The hot-dip galvanized steel sheet obtained by the above manufacturing method adopts a method of coating to the surface of the steel sheet once, and immediately after drying, is dried at 80 to 180 ° C to obtain hot-plating having a composite coating on the surface. Aluminum zinc plate. If the temperature is lower than 80 ° C, the cross-linking of the composite coating is insufficient to cause a decrease in its properties; if the temperature is higher than 180 ° C, the properties of some components in the surface treatment agent may change, thereby affecting the coating. The final effect of the composite coating on the steel sheet.

In the above technical solution, the composite coating layer may be directly coated on the surface of the hot-dip galvanized steel sheet by roll coating or spray coating.

For the above technical solution, the composite coating layer may be applied only on one side of the hot-dip aluminum-zinc steel sheet, or the composite coating layer may be coated on both sides of the hot-dip aluminum-zinc steel sheet.

The method for heating and drying the composite coating layer in the method for producing a hot-dip aluminized zinc-plated steel sheet according to the present invention is not particularly limited, and heating methods such as hot air heating, induction heating, and infrared heating may be employed.

After the surface of the hot-dip aluminum-zinc steel sheet according to the present invention is applied to the surface of the steel sheet, the steel sheet has excellent corrosion resistance, excellent stain resistance, good processability and good weather resistance.

In addition, the surface treatment agent of the present invention does not contain chromium and has good system state stability, and has better environmental and economic benefits.

The hot-dip aluminum-zinc plate according to the invention has good comprehensive properties such as corrosion resistance, stain resistance, weather resistance and processing property after being coated with a surface treatment agent.

The method for producing a hot-dip galvanized steel sheet according to the present invention can obtain a hot-dip galvanized steel sheet having excellent corrosion resistance, excellent surface anti-staining performance, good weather resistance and good processability.

detailed description

The surface treatment agent for hot-dip aluminum-zinc steel sheet and the hot-dip aluminum-zinc steel sheet and the manufacturing method thereof according to the present invention will be further explained and explained below with reference to specific embodiments. However, the explanation and description are not directed to the technology of the present invention. The program constitutes an improper limit.

Examples 1-7 and Comparative Examples 1-3

Each of Examples 1-7 and Comparative Examples 1-3 employs a hot-dip galvanized steel sheet having a thickness of 1.0 mm, and a surface treatment agent (each component in the surface treatment agent) is coated on at least one surface of the hot-dip galvanized steel sheet. The mass fractions are shown in Table 1), dried at 80-180 ° C to obtain a hot-dip galvanized steel sheet with a composite coating on the surface. The dry film thickness of the composite coating is 1-3 μm. For details of the drying process parameters, see Table 2.

Table 1 lists the parts by mass of the components of the composite coatings of Examples 1-7 and Comparative Examples 1-3.

Table 1.

*Note: A is an aqueous aliphatic polyurethane resin, B1 is vinyltrimethoxysilane, B2 is glycidoxypropyltrimethoxysilane, B3 is aminopropyltriethoxysilane; C is carbonized secondary Amine compound emulsion; D1 is vanadium oxide, D2 is ammonium fluorotitanate; E is zirconium carbonate; F1 is polyphosphate modified nano montmorillonite, F2 is nano bentonite, F3 is nano montmorillonite; G1 is poly Tetrafluoroethylene wax, G2 is polytetrafluoroethylene wax.

Table 2 lists the drying process parameters in the method of producing the hot-dip galvanized steel sheets of Examples 1-7 and Comparative Examples 1-3.

Table 2.

Serial number	Drying temperature (°C)
Example 1	100
Example 2	90
Example 3	120
Example 4	130
Example 5	110
Example 6	140
Example 7	150
Comparative example 1	80
Comparative example 2	120
Comparative example 3	120

The hot-dip galvanized steel sheets coated with the surface treatment agents in the above Examples 1-7 and Comparative Examples 1-3 were sampled and tested according to the following test methods, thereby obtaining the evaluations obtained. The test data for each performance is listed in Table 3. Among them, the test to evaluate its performance parameters is as follows:

1) Corrosion resistance

The test sample (plate) was subjected to a salt spray test with ASTM B117 and a test time of 240 hours. The evaluation criteria are as follows:

◎: the area ratio of white rust is less than or equal to 5%;

○: the area ratio of white rust is more than 5% and less than or equal to 10%;

Δ: the white rust area ratio is greater than 10% and less than or equal to 50%;

×: The area ratio of white rust is more than 50%.

2) Anti-staining performance

A 5% carbon black suspension was added dropwise on the surface of the test sample to form a nearly circular water stain with a diameter of about 50 mm. After baking in an oven at 60 ° C for 1 h, it was taken out, the surface residual carbon black was washed away, and dried, and the water was measured. The change of the color difference (ΔE*) in the stained area is as follows:

◎: the color difference value ΔE* is 3.0 or less, and the surface anti-staining performance is excellent;

○: the color difference value ΔE* is greater than 3.0 and less than or equal to 6.0;

Δ: color difference value ΔE* is greater than 6.0 and less than or equal to 9.0;

×: The color difference value ΔE* is more than 9.0, and the surface contamination is serious.

3) Processing performance

3a. After the T-bend test of the test sample, the peeling degree of the film after processing was evaluated by the tape peeling method, and the evaluation criteria were as follows:

◎: 2T film does not peel off;

○: 3T film is not peeled off;

Δ: 4T film without peeling off;

×: The 5T film was not peeled off.

3b. Test using the drawbead method, the experimental conditions: the pressure under the fixed bead is 3KN, the diameter of the indenter is 9.6 mm, and the drawing speed is 200 mm/min. Observe the appearance after drawing, and the evaluation criteria are as follows:

◎: No change in appearance;

○: A small amount of black spots appear;

Δ: the appearance is more obvious black stripes;

×: The appearance is completely black.

4) Weather resistance

The sample was placed in an ultraviolet aging test chamber (UVB-313 lamp), 8h for one cycle, 4h for ultraviolet light, blackboard temperature 60±3°C; 4h condensation, blackboard temperature 50±3°C, 600h after the appearance of the sample Observe and test its gloss retention rate as follows:

◎: There is no obvious change in the appearance of the sample, and the gloss retention rate is 70% or more;

○: The appearance of the sample plate changes little, and the gloss retention rate is 50% or more and less than 70%;

Δ: The appearance of the sample changes significantly, and the gloss retention rate is greater than or equal to 30% and less than 50%;

×: The appearance of the sample plate is seriously changed, and the gloss retention rate is less than 30%.

5) Storage stability

The surface treatment agent was placed at room temperature, and the solution was observed after 90 days. The evaluation criteria were as follows:

◎: no change;

○: slightly thickened (can be used normally);

Δ: severely thickened;

×: Gel.

Table 3 lists various performance parameters of the hot-dip galvanized steel sheets coated with the surface treatment agents in Examples 1-7 and Comparative Examples 1-3.

table 3.

As can be seen from Tables 1 and 3, since Comparative Example 1 does not contain the carbodiimide compound emulsion (C), the composite coating is insufficiently crosslinked, resulting in stain resistance, corrosion resistance and weather resistance. Poor (the evaluation result is "Δ" or "×"); since the water-dispersed nanoclay (F) is not added to Comparative Example 2, the composite coating has poor stain resistance (the evaluation result is "X" ”; Because the fluoropolymer-based lubricating aid (G) was not added to Comparative Example 3, the processing property of the steel sheet was poor (the evaluation result was “×”).

As can be seen from Table 3, compared with Comparative Examples 1-3, the hot-dip galvanized steel sheets of Examples 1-7 were subjected to the above tests, and the evaluation results were "◎" and "Ο", which indicates The hot-dip galvanized steel sheets coated by the surface treatment agent of the present invention all exhibit excellent corrosion resistance, excellent stain resistance, good weather resistance, and good processability. In addition, it can be seen that the stability of the storage state of the hot-dip galvanized steel sheets in Examples 1-7 is not easily changed after a long period of time, so that the surface treatment agent can be avoided as much as possible for the hot-dip aluminum-zinc steel sheet. The impact of the overall performance.

It is to be noted that the above is only specific embodiments of the present invention, and it is obvious that the present invention is not limited to the above embodiments, and there are many similar variations. All modifications that are directly derived or associated by those of ordinary skill in the art are intended to be within the scope of the invention.

Claims (10)

1. A surface treatment agent for hot-dip aluminum-zinc steel sheet, characterized in that the parts by mass of each component are:

   Aqueous aliphatic polyurethane resin: 45-85 parts;

   Silicone compound: 5-20 parts;

   Carbodiimide compound emulsion: 3-15 parts;

   a water-soluble metal salt compound, the mass fraction of which is based on the metal element: 1-5 parts;

   a water-soluble zirconium compound, the mass fraction of which is zirconia: 1-10 parts;

   Water-dispersible nanoclay: 1-10 parts;

   Fluoropolymer lubricant builder: 1-15 parts.
2. The surface treatment agent for hot-dip aluminum-zinc steel sheets according to claim 1, wherein the silicone-based compound is at least one of silicic acid, silicate, colloidal silica, and an organosilane coupling agent. .
3. The surface treatment agent for hot-dip aluminum-zinc steel sheets according to claim 2, wherein the silicone-based compound is an organosilane coupling agent, and the organosilane coupling agent is a vinyl-based silane coupling agent. At least one of an epoxy group-based silane coupling agent and a mercapto-based silane coupling agent.
4. The surface treatment agent for hot-dip aluminum-zinc steel sheets according to claim 1, wherein the water-soluble zirconium compound is zirconium carbonate.
5. The surface treatment agent for hot-dip galvanized steel sheets according to claim 1, wherein the water-dispersible nanoclay is at least one of nano montmorillonite, nano bentonite, and polyphosphate-modified nanobentonite. .
6. The surface treatment agent for hot-dip galvannealed steel sheets according to claim 1, wherein the fluoropolymer-based lubricating agent is a polytetrafluoroethylene wax and/or a polytetrafluoroethylene wax.
7. The surface treatment agent for hot-dip galvannealed steel sheets according to claim 1, wherein the fluoropolymer-based lubricating agent has an average particle diameter of 0.1 to 2.0 μm.
8. A hot-dip galvanized steel sheet having a surface having a composite coating coated with a surface treatment agent according to any one of claims 1-7.
9. The hot-dip galvanized steel sheet according to claim 8, wherein the composite coating has a dry film thickness of from 1 to 3 μm.
10. A method of manufacturing a hot-dip galvanized steel sheet according to claim 8, wherein: hot-plating A surface treatment agent is directly coated on at least one surface of the aluminum-zinc steel sheet, and dried at 80 to 180 ° C to obtain a hot-dip galvanized steel sheet having a composite coating on the surface.