阅读说明：本技术 热镀锌铝镁钢板表面处理液及热镀锌铝镁无铬钝化板的制备方法 (Surface treatment liquid for hot-dip galvanized aluminum magnesium steel plate and preparation method of hot-dip galvanized aluminum magnesium chromium-free passivated plate ) 是由 董学强 朱宁芳 徐接旺 周一林 于 2020-06-24 设计创作，主要内容包括：本发明公开了一种热镀锌铝镁钢板表面处理液及热镀锌铝镁无铬钝化板的制备方法,属于热镀锌铝镁钢板技术领域,所述热镀锌铝镁钢板表面处理液各成分含量以100重量份水为基准计,水性树脂乳液10～30重量份、弱酸性物质1～5重量份、硫脲3～10重量份、酸性硅烷偶联剂10～20重量份,多磷酸盐2～8重量份；所述热镀锌铝镁钢板的镀层化学成分按重量百分比计为1～5％Al、0.2～3％Mg,其余为Zn。本发明制备的热镀锌铝镁钢板表面处理液用于热镀锌铝镁板后,具有优异的环保性、涂装性、耐蚀性、耐黑变性、耐指纹性以及耐水性。(The invention discloses a hot-dip galvanized aluminum magnesium steel plate surface treatment liquid and a preparation method of a hot-dip galvanized aluminum magnesium chromate-free passivated plate, belonging to the technical field of hot-dip galvanized aluminum magnesium steel plates, wherein the hot-dip galvanized aluminum magnesium steel plate surface treatment liquid comprises, by weight, 100 parts of water, 10-30 parts of aqueous resin emulsion, 1-5 parts of weakly acidic substances, 3-10 parts of thiourea, 10-20 parts of acidic silane coupling agents and 2-8 parts of polyphosphates; the chemical components of a coating of the hot-dip galvanized aluminum-magnesium steel plate are 1-5% of Al, 0.2-3% of Mg and the balance of Zn in percentage by weight. The surface treatment liquid for the hot-dip galvanized aluminum-magnesium steel plate prepared by the invention has excellent environmental protection, coating property, corrosion resistance, black degeneration resistance, fingerprint resistance and water resistance after being used for hot-dip galvanized aluminum-magnesium plates.)

1. The surface treatment liquid for the hot-dip galvanized aluminum-magnesium steel plate is characterized by comprising 10-30 parts by weight of aqueous resin emulsion, 1-5 parts by weight of weakly acidic substances, 3-10 parts by weight of thiourea, 10-20 parts by weight of acidic silane coupling agent and 2-8 parts by weight of polyphosphate based on 100 parts by weight of water.

2. The surface treatment liquid for a galvanized aluminum-magnesium steel sheet according to claim 1, wherein the surface treatment liquid comprises 20 to 30 parts by weight of an aqueous resin emulsion, 2 to 3 parts by weight of a weakly acidic substance, 3 to 6 parts by weight of thiourea, 15 to 20 parts by weight of an acidic silane coupling agent, and 2 to 8 parts by weight of a polyphosphate, based on 100 parts by weight of water.

3. The surface treatment liquid for a hot-dip galvannealed magnesium-aluminum steel sheet according to claim 1 or 2, wherein the pH of the treatment liquid is 3.5 to 5.5.

4. The surface treatment liquid for the hot-dip galvanized aluminum-magnesium steel sheet according to any one of claims 1 to 3, wherein the solid content of the aqueous resin emulsion is 35 to 45%, and the aqueous resin emulsion is at least one selected from the group consisting of an aqueous acrylic emulsion, an aqueous styrene-acrylic emulsion, an aqueous fluorocarbon emulsion, an aqueous phenol-formaldehyde emulsion, an aqueous silicone-acrylic emulsion, an aqueous epoxy resin and an aqueous alkyd resin; preferably, the aqueous resin emulsion is an aqueous styrene-acrylic emulsion and/or an aqueous silicone-acrylic emulsion.

5. The liquid for surface treatment of a hot-dip galvanized aluminum-magnesium steel sheet according to any one of claims 1 to 3, wherein the weakly acidic substance is at least one of formic acid, acetic acid, propionic acid, butyric acid, oxalic acid, malonic acid, adipic acid, suberic acid, lactic acid, fruit acid, citric acid, maleic acid, benzoic acid, or lactic acid; preferably, the weakly acidic substance is oxalic acid and/or lactic acid.

6. The liquid for treating the surface of a hot-dip galvanized aluminum-magnesium steel sheet according to any one of claims 1 to 3, wherein the acidic silane coupling agent is 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-acetoxypropyltrimethoxysilane, 3-methacryloxypropyltriisopropoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, aluminum-magnesium-aluminum-magnesium-steel sheet, or a mixture thereof, At least one of 3-ureidopropyltrimethoxysilane, vinyltris (2-methoxyethoxy) silane, or 3-methacryloxypropyltrimethoxysilane; preferably, the acidic silane coupling agent is 3-mercaptopropyltriethoxysilane and/or 3-glycidyloxypropylmethyldimethoxysilane.

7. The liquid for surface treatment of a zinc-aluminum-magnesium plated steel sheet according to any one of claims 1 to 3, wherein the polyphosphate is at least one of sodium hexametaphosphate, sodium tripolyphosphate, potassium hexametaphosphate, potassium tripolyphosphate, ammonium hexametaphosphate, or ammonium tripolyphosphate; preferably, the polyphosphate is sodium tripolyphosphate and/or potassium hexametaphosphate.

8. The preparation method of the hot dip zinc aluminum magnesium steel plate surface treatment liquid according to any one of claims 1 to 7, characterized by comprising the steps of: dissolving thiourea in water, adding polyphosphate, adding a weakly acidic substance after complete dissolution, adding an acidic silane coupling agent after complete dissolution, adding an aqueous resin emulsion after complete hydrolysis, and stirring uniformly.

9. The preparation method of the hot galvanizing aluminum magnesium chromium-free passivation plate is characterized by comprising the following steps: a hot dip galvanized aluminum-magnesium alloy coated steel sheet coated with the surface treatment liquid for a hot dip galvanized aluminum-magnesium alloy steel sheet according to any one of claims 1 to 7, which is cured at 80 to 120 ℃ for 10 to 60 seconds, wherein the coating chemical composition of the hot dip galvanized aluminum-magnesium alloy coated steel sheet is, by weight, 1 to 5% of Al, 0.2 to 3% of Mg, and the balance Zn.

10. The hot-dip galvanized aluminum magnesium chromium-free passivation plate prepared by the preparation method of the hot-dip galvanized aluminum magnesium chromium-free passivation plate as claimed in claim 9, wherein the thickness of the chromium-free passivation coating of the passivation plate is 0.4-2.0 μm.

Technical Field

The invention belongs to the technical field of hot-dip galvanized aluminum-magnesium steel plates, and particularly relates to a surface treatment liquid for a hot-dip galvanized aluminum-magnesium steel plate and a preparation method of a hot-dip galvanized aluminum-magnesium chromium-free passivated plate.

Background

With the increasing requirement of the user market on the corrosion resistance of materials, hot-dip Galvanized (GI) and hot-dip 55% Al-Zn alloy coated (GL) steel plates and the like widely applied to the industries of buildings, automobiles, household appliance manufacturing and the like in various countries in the world at present belong to traditional coated steel plates, and hot-dip galvanized Zn-Al-Mg alloy coated steel plates are new coated steel plates produced by transportation.

The Zn-Al-Mg alloy coating has attracted wide attention abroad in the 80 s of the 20 th century, and becomes a research focus in the professional field of hot dip galvanizing and zinc alloy coating. From the research results of the same lines at home and abroad, the hot-dip galvanized Zn-Al-Mg alloy coated steel plate added with Mg has better corrosion resistance under the condition that the contents of Zn and Al of the coatings are at the same level, and the processing application performance (formability, weldability and paintability) of the material is excellent, so that the hot-dip galvanized Zn-Al-Mg alloy coated steel plate can replace the existing corresponding hot-dip galvanized or zinc alloy coated steel plate, and has very wide market demand prospect.

The existing hot dip Zn-Al-Mg alloy coated steel plate can be divided into three types of low aluminum (WAl is less than 5 percent), medium aluminum (WAl is more than or equal to 5 percent and less than 13 percent) and high aluminum (WAl is more than or equal to 47 percent and less than or equal to 57 percent). In the field of household appliance and automobile application, in order to ensure that a Zn-Al-Mg alloy coating steel plate meets the punch forming requirement of a user, a low-aluminum component system is required to have good formability.

Because a large amount of Al and Mg elements exist on the surface of the zinc-aluminum-magnesium alloy coating, the zinc-aluminum-magnesium alloy coating is very easy to oxidize, blacken and rusted in severe cases in the process of placement, storage and transportation. In order to improve the corrosion resistance and prevent blackening of the zinc-aluminum-magnesium alloy coated steel sheet, a surface treatment is required, and therefore, the surface coating must have a coating property. However, the current domestic environment-friendly surface treatment technology of the zinc-aluminum-magnesium coated steel plate is not mature, and the problems of blackening resistance and poor corrosion resistance of a common chromium-free passivation coating are found in the surface treatment test process of the zinc-aluminum-magnesium coated steel plate, so that the requirements that the NSST/72h corrosion area is less than or equal to 5 and the color difference is less than or equal to 4 cannot be met, the coating performance is not provided, and the product application is not facilitated.

In order to realize the application of the zinc-aluminum-magnesium alloy coating steel plate product variety in different parts of household appliances and automobiles, the development of the hot-dip zinc-aluminum-magnesium alloy coating chromium-free passivated plate with the performances of coating property and the like has very important significance.

Disclosure of Invention

The invention aims to provide a hot-dip galvanized aluminum-magnesium chromate-free passivated sheet with excellent environmental protection, coating property, corrosion resistance, blackening resistance, fingerprint resistance and water resistance.

In order to achieve the above object, the present invention provides a hot dip zinc aluminum magnesium plated steel sheet surface treatment liquid, wherein the treatment liquid comprises 10 to 30 parts by weight of an aqueous resin emulsion, 1 to 5 parts by weight of a weakly acidic substance, 3 to 10 parts by weight of thiourea, 10 to 20 parts by weight of an acidic silane coupling agent, and 2 to 8 parts by weight of a polyphosphate, based on 100 parts by weight of water.

Further, the hot dip zinc aluminum magnesium plated steel sheet surface treatment liquid comprises 20 to 30 parts by weight of an aqueous resin emulsion, 2 to 3 parts by weight of a weakly acidic substance, 3 to 6 parts by weight of thiourea, 15 to 20 parts by weight of an acidic silane coupling agent, and 2 to 8 parts by weight of a polyphosphate, based on 100 parts by weight of water.

Further, the pH value of the hot dip galvanizing aluminum magnesium steel plate surface treatment liquid is 3.5-5.5.

Further, in the hot dip galvanized aluminum magnesium steel plate surface treatment liquid, the solid content of the aqueous resin emulsion is 35-45%, and the aqueous resin emulsion is selected from at least one of aqueous acrylic emulsion, aqueous styrene-acrylic emulsion, aqueous fluorocarbon emulsion, aqueous phenolic emulsion, aqueous silicone-acrylic emulsion, aqueous epoxy resin or aqueous alkyd resin; preferably, the aqueous resin emulsion is an aqueous styrene-acrylic emulsion and/or an aqueous silicone-acrylic emulsion.

Further, in the hot dip galvanizing aluminum magnesium steel plate surface treatment solution, the weakly acidic substance is at least one of formic acid, acetic acid, propionic acid, butyric acid, oxalic acid, malonic acid, adipic acid, suberic acid, lactic acid, fruit acid, citric acid, maleic acid, benzoic acid or lactic acid; preferably, the weakly acidic substance is oxalic acid and/or lactic acid.

Further, in the above hot dip zinc aluminum magnesium plated steel sheet surface treatment liquid, the acidic silane coupling agent is 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-acetoxypropyltrimethoxysilane, 3-methacryloxypropyltriisopropoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, 3-ureidopropyltrimethoxysilane, aluminum magnesium plated steel sheet surface treatment liquid, At least one of vinyltris (2-methoxyethoxy) silane or 3-methacryloxypropyltrimethoxysilane; preferably, the acidic silane coupling agent is 3-mercaptopropyltriethoxysilane and/or 3-glycidyloxypropylmethyldimethoxysilane.

Further, in the hot dip zinc aluminum magnesium plated steel sheet surface treatment liquid, the polyphosphate is at least one of sodium hexametaphosphate, sodium tripolyphosphate, potassium hexametaphosphate, potassium tripolyphosphate, ammonium hexametaphosphate, or ammonium tripolyphosphate; preferably, the polyphosphate is sodium tripolyphosphate and/or potassium hexametaphosphate.

The invention also provides a preparation method of the hot dip galvanizing aluminum magnesium steel plate surface treatment liquid, which comprises the following steps: dissolving thiourea in water, adding polyphosphate, adding a weakly acidic substance after complete dissolution, adding an acidic silane coupling agent after complete dissolution, adding an aqueous resin emulsion after complete hydrolysis, and stirring uniformly.

The invention also provides a preparation method of the hot-dip galvanized aluminum-magnesium chromium-free passivation plate, which comprises the following steps: a hot dip galvanized aluminum-magnesium alloy coated steel sheet coated with the surface treatment liquid for a hot dip galvanized aluminum-magnesium alloy steel sheet according to any one of claims 1 to 7, which is cured at 80 to 120 ℃ for 10 to 60 seconds, wherein the coating chemical composition of the hot dip galvanized aluminum-magnesium alloy coated steel sheet is, by weight, 1 to 5% of Al, 0.2 to 3% of Mg, and the balance Zn.

The invention also provides a hot-dip galvanized aluminum magnesium chromium-free passivation plate prepared by the preparation method of the hot-dip galvanized aluminum magnesium chromium-free passivation plate, wherein the thickness of a chromium-free passivation coating of the passivation plate is 0.4-2.0 mu m.

Compared with the prior art, the invention has the beneficial effects that:

the hot dip zinc aluminum magnesium steel plate surface treatment liquid provided by the invention does not contain chromium, does not cause harm to human bodies and environment, and is good in environmental protection; the hot-dip galvanized aluminum magnesium steel plate surface treatment liquid provided by the invention has good stability and synergistic effect of various components, and the hot-dip galvanized aluminum magnesium chromium-free passivated plate formed after coating and curing has excellent performances such as coating property, corrosion resistance, black degeneration resistance, fingerprint resistance, water resistance and the like.

Detailed Description

Aiming at the performance requirements that a hot-dip galvanized aluminum-magnesium alloy coating is easy to blacken and needs to be coated after stamping, the invention improves the corrosion resistance, the blackening resistance, the coating property, the water resistance and the fingerprint resistance of the passivation film layer by enhancing the sealing effect of the film layer and the binding force of the passivation film layer and the coating layer and the vitrification and spraying coating layer, and meets the stamping and spraying requirements of household appliances and automobile users. Specifically, the invention firstly provides a hot-dip galvanized aluminum magnesium steel plate surface treatment liquid, which comprises 10-30 parts by weight of aqueous resin emulsion, 1-5 parts by weight of weakly acidic substances, 3-10 parts by weight of thiourea, 10-20 parts by weight of acidic silane coupling agent and 2-8 parts by weight of polyphosphate based on 100 parts by weight of water.

The hot dip zinc aluminum magnesium steel plate surface treatment liquid takes the water-based resin as a main film forming substance, and the hydrolyzed silane coupling agent reacts with the coating on one hand and reacts with the water-based resin in a crosslinking way on the other hand, so that the binding force between the coating and the surface passivation film layer is enhanced, and the binding force with a vitrified and sprayed coating is facilitated, thereby enhancing the sealing effect of the passivation film layer and improving the coating performance; thiourea and polyphosphate can react with the coating to form a film, and can be filled in gaps of the film, so that the sealing effect of the passivation film is enhanced, and the corrosion resistance and the blackening resistance of the passivation film are improved.

The weight proportion of the treatment fluid is determined by combining the conditions of membrane formation and the synergistic effect of the components, and if the proportion is not in the range of the invention, the effect of the treatment fluid is poor.

In order to ensure sufficient hydrolysis of the silane coupling agent, the pH of the surface treatment liquid of the present invention must be controlled to 3.5 to 5.5, and this range of pH is also the basis for stable storage of the surface treatment liquid.

The following examples are provided to further illustrate the embodiments of the present invention and are not intended to limit the scope of the present invention.

Surface treatment liquid for hot-dip galvanized aluminum magnesium steel plate and preparation of hot-dip galvanized aluminum magnesium chromium-free passivated plate

1. The surface treatment liquid of the hot-dip galvanized aluminum magnesium steel plate comprises the following steps:

firstly, weighing each component according to the content of each component of the hot-dip galvanized aluminum-magnesium steel plate surface treatment liquid in the table 1, firstly, dissolving thiourea in water, then adding polyphosphate, adding a weakly acidic substance after complete dissolution, adding an acidic silane coupling agent after complete dissolution, completely hydrolyzing after 1h, adding a water-based resin emulsion, uniformly stirring, and standing for 30min to obtain the hot-dip galvanized aluminum-magnesium steel plate surface treatment liquid prepared by the invention.

2. Preparing a hot-dip galvanized aluminum-magnesium chromium-free passivation plate:

preparing a hot dip galvanized aluminum magnesium alloy coating steel plate by a conventional method, respectively roll-coating the surface treatment liquid of the hot dip galvanized aluminum magnesium alloy coating steel plate prepared in the step 1 on a hot dip galvanized aluminum magnesium alloy coating steel plate with 2% of Al and 2% of Mg and Zn, curing for 20s at the curing temperature of 100 ℃ to form a chromium-free passivation coating with the thickness of 0.4-2.0 mu m, and cooling to room temperature to obtain the hot dip galvanized aluminum magnesium alloy coating chromium-free passivation plate.

TABLE 1 composition (parts by weight) and pH of surface treatment liquid for hot-dip galvanized aluminum-magnesium steel sheets

	Water (W)	Aqueous resin emulsion	Weakly acidic substance	Thiourea	Silane coupling agent	Polyphosphates	pH
								Example 1	100	20	3	6	15	5	4.5
Example 2	100	10	5	10	12	6	3.5
								Example 3	100	15	4	8	10	4	4.0
Example 4	100	25	2	3	20	2	5.0
								Example 5	100	30	3	5	18	8	4.5
Comparative example 1	100	0	3	6	15	5	4.5
								Comparative example 2	100	20	0	6	15	5	8.5
Comparative example 3	100	20	3	0	15	5	4.0
								Comparative example 4	100	20	3	6	0	5	4.0
Comparative example 5	100	20	3	6	15	0	4.0
								Example 6	100	20	3	6	15	5	4.5
Example 7	100	20	3	6	15	5	4.5
								Example 8	100	20	3	6	15	5	4.5
Example 9	100	20	3	6	15	5	4.5