An environmentally friendly waterborne corrosion-resistant metal baking paint and its preparation method

Abstract

The present invention discloses an environmentally friendly waterborne corrosion-resistant metal baking paint and a preparation method thereof, belonging to the technical field of metal baking paints. The method comprises the following steps: mixing dipropylene glycol methyl ether and dipropylene glycol butyl ether, stirring, adding them into a waterborne acrylic-amino resin emulsion, mixing, adding N,N-dimethylethanolamine, adding a curing agent, mixing, adding deionized water, mixing, adding a silver discharge aid, and mixing to obtain a varnish; taking aluminum powder and ethylene glycol butyl ether to prepare a pre-dispersed slurry, and mixing it with the varnish to obtain an aluminum paint; taking 2-(p-dodecyloxyphenyl)pyrazine-5-carboxylic acid, chromium hydroxide, and sulfuric acid solution, heating and stirring, adding potassium chromate and deionized water, ultrasonically dispersing, and spraying it on the surface of the aluminum paint to obtain the environmentally friendly waterborne metal baking paint with excellent corrosion resistance.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal baking varnish, and particularly relates to an environmentally friendly waterborne corrosion-resistant metal baking varnish and a preparation method thereof. Background Art

[0002] Traditional metal baking varnishes usually contain organic solvents, which not only cause environmental pollution but also pose hazards to human health. Therefore, the development of environmentally friendly waterborne metal baking varnishes has important practical significance and application value. Metallic flake paint, as a unique type of metal baking varnish, always occupies a place in the coating field due to its fascinating color-changing effect with viewing angle and distinct metallic texture. Especially in modern industrial design fields such as automobiles and 3C digital products, the application of metallic flake paint can better highlight the high-end and luxurious visual effects. However, behind the beauty of this coating, there are challenges in corrosion resistance.

[0003] In metallic flake paint, especially aluminum powder paint, the aluminum powder particles are exposed, which makes it extremely vulnerable to the external environment. When exposed to various climatic conditions, chemical substances, and harsh environments with high salinity, the aluminum powder particles may accelerate the oxidation reaction, thereby reducing the corrosion resistance of the material. This corrosion phenomenon not only affects the beauty of the metallic flake paint but may also shorten the service life of the product. Summary of the Invention

[0004] The present invention discloses an environmentally friendly waterborne corrosion-resistant metal baking varnish and a preparation method thereof, belonging to the technical field of metal baking varnish. The method includes the following steps: Mix dipropylene glycol methyl ether and dipropylene glycol butyl ether, stir, add them to a waterborne acrylic-amine resin emulsion, mix, add N,N-dimethylethanolamine, add a curing agent, mix, add deionized water, mix, add a silver discharge aid, and mix to obtain a clear varnish; Take aluminum powder and ethylene glycol monobutyl ether and mix them to prepare a pre-dispersed slurry, and mix it with the clear varnish to obtain an aluminum paint; Take 2-(p-dodecyloxyphenyl)pyrazine-5-carboxylic acid, chromium hydroxide, and sulfuric acid solution, heat and stir, add potassium chromate and deionized water, ultrasonically disperse, and spray it on the surface of the aluminum paint to obtain the environmentally friendly waterborne metal baking varnish with excellent corrosion resistance.

[0005] The technical problem to be solved by the present invention is to produce an environmentally friendly waterborne metal baking varnish with excellent corrosion resistance.

[0006] The object of the present invention can be achieved by the following technical solutions:

[0007] A preparation method of an environmentally friendly waterborne corrosion-resistant metal baking varnish includes the following steps:

[0008] S1. Mix dipropylene glycol methyl ether and dipropylene glycol butyl ether, stir for 20 - 30 min, add them to the aqueous acrylic - amino resin emulsion under stirring, mix at a rotation speed of 500 - 600 r / min for 5 - 8 min, then add N,N - dimethylethanolamine with a mass fraction of 10%, mix at a rotation speed of 500 - 600 r / min for 5 - 6 min, add deionized water, continue to mix at a rotation speed of 500 - 600 r / min for 5 - 6 min, add a silver - discharging aid, and mix at a rotation speed of 600 - 800 r / min for 5 - 6 min to obtain a varnish;

[0009] S2. Take aluminum powder and place it in a stirring kettle, add ethylene glycol butyl ether, stir for 20 - 30 min, let it stand for 1 - 2 h to obtain a pre - dispersed slurry, mix the pre - dispersed slurry and the varnish, and stir for 15 - 30 min to obtain an aluminum paint;

[0010] S3. Take 2 - (p - dodecyloxyphenyl)pyrazine - 5 - carboxylic acid, chromium hydroxide, and sulfuric acid solution, mix them, stir in a water bath at 80 - 90 °C for 2 - 3 h, add potassium chromate and deionized water, ultrasonically disperse for 1 - 2 h, and spray it onto the surface of the aluminum paint at a spraying speed of 120 mL / min; during the spraying process, the aluminum paint is continuously stirred at a stirring speed of 500 - 600 r / min to obtain the environmentally friendly water - borne corrosion - resistant metal baking paint.

[0011] As a preferred technical solution of the present invention, in step S1, the mass ratio of the dipropylene glycol methyl ether, dipropylene glycol butyl ether, aqueous acrylic - amino resin emulsion, N,N - dimethylethanolamine, deionized water, and silver - discharging aid is 3 - 5:2 - 3:40 - 60:4 - 6:20 - 30:10 - 20.

[0012] As a preferred technical solution of the present invention, the silver - discharging aid is cellulose acetate butyrate.

[0013] As a preferred technical solution of the present invention, the concentration of the sulfuric acid solution is 1 - 2 mol / L.

[0014] As a preferred technical solution of the present invention, in step S2, the mass ratio of the aluminum powder, ethylene glycol butyl ether, and varnish is 6 - 8:7 - 9:80 - 100.

[0015] As a preferred technical solution of the present invention, in step S3, the dosage ratio of the 2 - (p - dodecyloxyphenyl)pyrazine - 5 - carboxylic acid, chromium hydroxide, sulfuric acid solution, potassium chromate, deionized water, and aluminum paint is 10 - 20 g:5 - 8 g:100 mL:6 - 8 g:500 mL:90 - 100 g.

[0016] As a preferred technical solution of the present invention, the preparation of the aqueous acrylic - amino resin emulsion includes the following steps:

[0017] S11. Add deionized water, a composite emulsifier, and glycidyl versatate into a reaction kettle under a nitrogen atmosphere, stir for 1 - 2 h, heat up to 80 °C, add methyl methacrylate, butyl acrylate, and potassium persulfate, stir for 2 - 3 h, continue to add deionized water, the composite emulsifier, methyl methacrylate, butyl acrylate, and potassium persulfate, stir for 1 - 2 h, add methacrylic acid and 2 - hydroxyethyl acrylate, stir for 1 - 2 h, heat up to 86 °C, keep warm for 1 - 2 h, adjust the pH to 5 - 6, filter, and discharge to obtain an acrylate emulsion;

[0018] S12. Take an amino resin, ethylene glycol monobutyl ether, and dodecyl mercaptan, mix them, stir for 1 - 2 h, add the acrylate emulsion, continue to stir for 2 - 4 h, add an antifoaming agent, a leveling agent, and deionized water, and adjust the pH to 8 - 9 to obtain the aqueous acrylic - amino resin emulsion.

[0019] As a preferred technical solution of the present invention, the antifoaming agent is Degussa 902W antifoaming agent, with the model of TEGO Airex 902W, purchased from Guangzhou Yinman New Materials Co., Ltd.

[0020] As a preferred technical solution of the present invention, the leveling agent is Disparlon AQ - 7180, purchased from Guangzhou Situlong Chemical Co., Ltd.

[0021] As a preferred technical solution of the present invention, in step S11, the mass ratio of the deionized water added for the first time, the composite emulsifier added for the first time, glycidyl versatate, the methyl methacrylate added for the first time, the butyl acrylate added for the first time, the potassium persulfate added for the first time, the deionized water added for the second time, the composite emulsifier added for the second time, the methyl methacrylate added for the second time, the butyl acrylate added for the second time, the potassium persulfate added for the second time, methacrylic acid, and 2 - hydroxyethyl acrylate is 100:2 - 4:20 - 25:20 - 25:20 - 25:0.2 - 0.3:100:1 - 2:20 - 25:40 - 50:0.15 - 0.25:7 - 8:7 - 8.

[0022] As a preferred technical solution of the present invention, in step S12, the mass ratio of the amino resin, ethylene glycol monobutyl ether, dodecyl mercaptan, acrylate emulsion, antifoaming agent, leveling agent, and deionized water is 10 - 20:8 - 10:0.1 - 0.15:50 - 65:0.1 - 0.2:0.2 - 0.3:30 - 40.

[0023] As a preferred technical solution of the present invention, the composite emulsifier is composed of an anionic reactive emulsifier and a non - ionic reactive emulsifier.

[0024] As a preferred technical solution of the present invention, the mass ratio of the anionic reactive emulsifier to the nonionic reactive emulsifier is 4:1 - 1.5.

[0025] As a preferred technical solution of the present invention, the anionic reactive emulsifier is allyloxy nonylphenol polyoxyethylene (10) ether ammonium sulfate, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0026] As a preferred technical solution of the present invention, the nonionic reactive emulsifier is nonionic reactive emulsifier SM-JR-2, purchased from Shaoxing Shangyu Smo Organic Chemistry Research Institute.

[0027] An environmentally friendly waterborne corrosion-resistant metal baking paint prepared by using the preparation method of the above-mentioned environmentally friendly waterborne corrosion-resistant metal baking paint.

[0028] Advantages of the present invention:

[0029] An environmentally friendly waterborne corrosion-resistant metal baking paint and its preparation method disclosed by the present invention obtain a waterborne acrylic-amine resin emulsion by preparing an acrylate emulsion with a core-shell structure to wrap an amino resin, which has good stability; further, adding a para-bicyclic carboxylic acid compound 2-(p-dodecyloxyphenyl)pyrazine-5-carboxylic acid containing a pyrazine ring forms a film on the surface of the aluminum paint to prevent the aluminum powder from being corroded and enhance the corrosion resistance of the paint film; further, introducing Cr 3+ as a film skeleton, so that the paint film has a certain thickness and corrosion resistance, introducing Cr 6+ , when the solvent evaporates, Cr 6+ precipitates and fills the pores of the aluminum paint, increasing the density of the paint film and improving its corrosion resistance. Specific embodiments

[0030] To further elaborate on the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the following combines examples to detail the specific embodiments, structures, features and their effects according to the present invention.

[0031] Example 1

[0032] A preparation method of an environmentally friendly waterborne corrosion-resistant metal baking paint, comprising the following steps:

[0033] S1. Mix dipropylene glycol methyl ether and dipropylene glycol butyl ether, stir for 20 min, add them to the aqueous acrylic - amino resin emulsion under stirring, mix at a rotation speed of 500 r / min for 8 min, then add N,N - dimethylethanolamine with a mass fraction of 10%, mix at a rotation speed of 500 r / min for 6 min, add deionized water, continue to mix at a rotation speed of 500 r / min for 6 min, add the silver - discharging aid cellulose acetate butyrate, and mix at a rotation speed of 600 r / min for 6 min to obtain the varnish;

[0034] The mass ratio of the dipropylene glycol methyl ether, dipropylene glycol butyl ether, aqueous acrylic - amino resin emulsion, N,N - dimethylethanolamine, deionized water, and silver - discharging aid is 3:2:40:4:20:10;

[0035] S2. Take aluminum powder and place it in a stirring kettle, add ethylene glycol monobutyl ether, stir for 20 min, and let it stand for 1 h to obtain a pre - dispersed slurry. Mix the pre - dispersed slurry and the varnish, and stir for 15 min to obtain the aluminum paint;

[0036] The mass ratio of the aluminum powder, ethylene glycol monobutyl ether, and varnish is 6:7:80;

[0037] S3. Take 2 - (p - dodecyloxyphenyl)pyrazine - 5 - carboxylic acid, chromium hydroxide, and a sulfuric acid solution with a concentration of 1 mol / L, mix them, stir in a water bath at 80 °C for 2 h, add potassium chromate and deionized water, ultrasonically disperse for 1 h, and spray them on the surface of the aluminum paint at a spraying speed of 120 mL / min. During the spraying process, the aluminum paint is continuously stirred at a stirring speed of 500 r / min to obtain the environmentally friendly water - borne corrosion - resistant metal baking paint;

[0038] The dosage ratio of the 2 - (p - dodecyloxyphenyl)pyrazine - 5 - carboxylic acid, chromium hydroxide, sulfuric acid solution, potassium chromate, deionized water, and aluminum paint is 10 g:5 g:100 mL:6 g:500 mL:90 g.

[0039] The preparation of the aqueous acrylic - amino resin emulsion includes the following steps:

[0040] S11. In a nitrogen atmosphere, add 100 parts by mass of deionized water, 2 parts by mass of a composite emulsifier, and 20 parts by mass of glycidyl versatate into a reaction kettle, stir for 1 h, heat up to 80 °C, add 20 parts by mass of methyl methacrylate, 20 parts by mass of butyl acrylate, and 0.2 parts by mass of potassium persulfate, stir for 2 h, continue to add 100 parts by mass of deionized water, 1 part by mass of the composite emulsifier, 20 parts by mass of methyl methacrylate, 40 parts by mass of butyl acrylate, and 0.15 parts by mass of potassium persulfate, stir for 1 h, add 7 parts by mass of methacrylic acid and 7 parts by mass of 2-hydroxyethyl acrylate, stir for 1 h, heat up to 86 °C, keep warm for 1 h, adjust the pH to 5, filter, and discharge to obtain an acrylate emulsion; the composite emulsifier consists of 4 parts by mass of allyloxy nonylphenol polyoxyethylene (10) ether ammonium sulfate and 1 part by mass of non-ionic reactive emulsifier SM-JR-2;

[0041] S12. Take 10 parts by mass of amino resin, 8 parts by mass of ethylene glycol monobutyl ether, and 0.1 part by mass of dodecyl mercaptan, mix and stir for 1 h, add the 50 parts by mass of acrylate emulsion, continue to stir for 2 h, add 0.1 part by mass of Degussa 902W defoamer, 0.2 part by mass of Disparlon AQ-7180, and 30 parts by mass of deionized water, adjust the pH to 8, and obtain the waterborne acrylic-amino resin emulsion.

[0042] Example 2

[0043] A preparation method of an environmentally friendly waterborne corrosion-resistant metal baking paint, comprising the following steps:

[0044] S1. Mix dipropylene glycol methyl ether and dipropylene glycol butyl ether, stir for 25 min, add them to the waterborne acrylic-amino resin emulsion under stirring, mix at a rotation speed of 550 r / min for 7 min, then add 10% by mass of N,N-dimethylethanolamine, mix at a rotation speed of 550 r / min for 5.5 min, add deionized water, continue to mix at a rotation speed of 550 r / min for 5.5 min, add the silver discharge aid cellulose acetate butyrate, and mix at a rotation speed of 700 r / min for 5.5 min to obtain a varnish;

[0045] The mass ratio of dipropylene glycol methyl ether, dipropylene glycol butyl ether, waterborne acrylic-amino resin emulsion, N,N-dimethylethanolamine, deionized water, and silver discharge aid is 4:2.5:50:5:25:15;

[0046] S2. Place aluminum powder in a stirring kettle, add ethylene glycol monobutyl ether, stir for 25 min, let stand for 1.5 h to obtain a pre-dispersed slurry, mix the pre-dispersed slurry and the varnish, and stir for 23 min to obtain an aluminum paint;

[0047] The mass ratio of the aluminum powder, ethylene glycol monobutyl ether, and varnish is 7:8:90;

[0048] S3. Take 2-(p-dodecyloxyphenyl)pyrazine-5-carboxylic acid, chromium hydroxide, and a sulfuric acid solution with a concentration of 1.5 mol / L, mix them, stir in a water bath at 85°C for 2.5 h, add potassium chromate and deionized water, ultrasonically disperse for 1.5 h, and spray them onto the surface of the aluminum paint at a spraying speed of 120 mL / min; during the spraying process, the aluminum paint is continuously stirred at a stirring speed of 550 r / min to obtain the environmentally friendly waterborne corrosion-resistant metal baking paint;

[0049] The dosage ratio of the 2-(p-dodecyloxyphenyl)pyrazine-5-carboxylic acid, chromium hydroxide, sulfuric acid solution, potassium chromate, deionized water, and aluminum paint is 15 g:6 g:100 mL:7 g:500 mL:95 g.

[0050] The preparation of the waterborne acrylic-amine resin emulsion includes the following steps:

[0051] S11. Add 100 parts by mass of deionized water, 3 parts by mass of a composite emulsifier, and 22 parts by mass of glycidyl versatate into a reaction kettle under a nitrogen atmosphere, stir for 1.5 h, heat up to 80°C, add 22 parts by mass of methyl methacrylate, 22 parts by mass of butyl acrylate, and 0.25 parts by mass of potassium persulfate, stir for 2.5 h, then continue to add 100 parts by mass of deionized water, 1.5 parts by mass of the composite emulsifier, 23 parts by mass of methyl methacrylate, 45 parts by mass of butyl acrylate, and 0.2 parts by mass of potassium persulfate, stir for 1.5 h, add 7.5 parts by mass of methacrylic acid and 7.5 parts by mass of 2-hydroxyethyl acrylate, stir for 1.5 h, heat up to 86°C, keep warm for 1.5 h, adjust the pH to 5.5, filter, and discharge to obtain an acrylate emulsion; the composite emulsifier consists of 4 parts by mass of allyloxy nonylphenol polyoxyethylene (10) ether ammonium sulfate and 1.2 parts by mass of a nonionic reactive emulsifier SM-JR-2;

[0052] S12. Take 15 parts by mass of amino resin, 9 parts by mass of ethylene glycol monobutyl ether, and 0.13 parts by mass of dodecyl mercaptan, mix and stir for 1.5 h, add the 60 parts by mass of acrylate emulsion, continue to stir for 3 h, add 0.15 parts by mass of Degussa 902W defoamer, 0.25 parts by mass of Disparlon AQ-7180, and 35 parts by mass of deionized water, and adjust the pH to 8.5 to obtain the waterborne acrylic-amine resin emulsion.

[0053] Example 3

[0054] A preparation method of an environmentally friendly waterborne corrosion-resistant metal baking paint includes the following steps:

[0055] S1. Mix dipropylene glycol methyl ether and dipropylene glycol butyl ether, stir for 30 min, add them to the waterborne acrylic-amino resin emulsion under stirring, mix at a rotation speed of 600 r / min for 5 min, then add N,N-dimethylethanolamine with a mass fraction of 10%, mix at a rotation speed of 600 r / min for 5 min, add deionized water, continue to mix at a rotation speed of 600 r / min for 5 min, add the silver discharge aid cellulose acetate butyrate, and mix at a rotation speed of 800 r / min for 5 min to obtain the varnish;

[0056] The mass ratio of the dipropylene glycol methyl ether, dipropylene glycol butyl ether, waterborne acrylic-amino resin emulsion, N,N-dimethylethanolamine, deionized water, and silver discharge aid is 5:3:60:6:30:20;

[0057] S2. Take aluminum powder and place it in a stirring kettle, add ethylene glycol monobutyl ether, stir for 30 min, and let it stand for 2 h to obtain a pre-dispersed slurry. Mix the pre-dispersed slurry and the varnish, and stir for 30 min to obtain the aluminum paint;

[0058] The mass ratio of the aluminum powder, ethylene glycol monobutyl ether, and varnish is 8:9:100;

[0059] S3. Take 2-(p-dodecyloxyphenyl)pyrazine-5-carboxylic acid, chromium hydroxide, and a sulfuric acid solution with a concentration of 2 mol / L, mix them, stir in a water bath at 90 °C for 3 h, add potassium chromate and deionized water, ultrasonically disperse for 2 h, and spray them on the surface of the aluminum paint at a spraying speed of 120 mL / min; during the spraying process, the aluminum paint is continuously stirred at a stirring speed of 600 r / min to obtain the environmentally friendly waterborne corrosion-resistant metal baking paint;

[0060] The dosage ratio of the 2-(p-dodecyloxyphenyl)pyrazine-5-carboxylic acid, chromium hydroxide, sulfuric acid solution, potassium chromate, deionized water, and aluminum paint is 20 g:8 g:100 mL:8 g:500 mL:100 g.

[0061] The preparation of the waterborne acrylic-amino resin emulsion includes the following steps:

[0062] S11. In a nitrogen atmosphere, add 100 parts by mass of deionized water, 4 parts by mass of a composite emulsifier, and 25 parts by mass of glycidyl versatate to a reaction kettle, stir for 2 h, heat up to 80 °C, add 25 parts by mass of methyl methacrylate, 25 parts by mass of butyl acrylate, and 0.3 parts by mass of potassium persulfate, stir for 3 h, continue to add 100 parts by mass of deionized water, 2 parts by mass of the composite emulsifier, 25 parts by mass of methyl methacrylate, 50 parts by mass of butyl acrylate, and 0.25 parts by mass of potassium persulfate, stir for 2 h, add 8 parts by mass of methacrylic acid and 8 parts by mass of 2-hydroxyethyl acrylate, stir for 2 h, heat up to 86 °C, keep warm for 2 h, adjust the pH to 6, filter, and discharge to obtain an acrylate emulsion; the composite emulsifier consists of 4 parts by mass of allyloxy nonylphenol polyoxyethylene (10) ether ammonium sulfate and 1.5 parts by mass of a nonionic reactive emulsifier SM-JR-2;

[0063] S12. Take 20 parts by mass of an amino resin, 10 parts by mass of ethylene glycol monobutyl ether, and 0.15 parts by mass of dodecyl mercaptan, mix and stir for 2 h, add the 65 parts by mass of the acrylate emulsion, continue to stir for 4 h, add 0.2 parts by mass of Degussa 902W defoamer, 0.3 parts by mass of Disparlon AQ-7180, and 40 parts by mass of deionized water, adjust the pH to 9, and obtain the aqueous acrylic-amino resin emulsion.

[0064] Comparative Example 1

[0065] The difference from Example 1 is that the preparation of the aqueous acrylic-amino resin emulsion includes the following steps:

[0066] S11. In a nitrogen atmosphere, add 200 parts by mass of deionized water, 3 parts by mass of a composite emulsifier, and 20 parts by mass of glycidyl versatate to a reaction kettle, stir for 1 h, heat up to 80 °C, add 40 parts by mass of methyl methacrylate, 60 parts by mass of butyl acrylate, and 0.35 parts by mass of potassium persulfate, stir for 3 h, add 7 parts by mass of methacrylic acid and 7 parts by mass of 2-hydroxyethyl acrylate, stir for 1 h, heat up to 86 °C, keep warm for 1 h, adjust the pH to 5, filter, and discharge to obtain an acrylate emulsion; the composite emulsifier consists of 4 parts by mass of allyloxy nonylphenol polyoxyethylene (10) ether ammonium sulfate and 1 part by mass of a nonionic reactive emulsifier SM-JR-2;

[0067] S12. Take 10 parts by mass of an amino resin, 8 parts by mass of ethylene glycol monobutyl ether, and 0.1 parts by mass of dodecyl mercaptan, mix and stir for 1 h, add the 50 parts by mass of the acrylate emulsion, continue to stir for 2 h, add 0.1 parts by mass of Degussa 902W defoamer, 0.2 parts by mass of Disparlon AQ-7180, and 30 parts by mass of deionized water, adjust the pH to 8, and obtain the aqueous acrylic-amino resin emulsion.

[0068] Comparative Example 2

[0069] The difference from Example 1 is that the preparation of the aqueous acrylic - amino resin emulsion includes the following steps:

[0070] S11. Add 100 parts by mass of deionized water, 2 parts by mass of emulsifier, and 20 parts by mass of glycidyl versatate into a reaction kettle under a nitrogen atmosphere, stir for 1 h, heat up to 80 °C, add 20 parts by mass of methyl methacrylate, 20 parts by mass of butyl acrylate, and 0.2 part by mass of potassium persulfate, stir for 2 h, then continue to add 100 parts by mass of deionized water, 1 part by mass of emulsifier, 20 parts by mass of methyl methacrylate, 40 parts by mass of butyl acrylate, and 0.15 part by mass of potassium persulfate, stir for 1 h, add 7 parts by mass of methacrylic acid and 7 parts by mass of 2 - hydroxyethyl acrylate, stir for 1 h, heat up to 86 °C, keep warm for 1 h, adjust the pH to 5, filter, and discharge to obtain an acrylate emulsion; the emulsifier is allyloxy nonylphenol polyoxyethylene (10) ether ammonium sulfate salt;

[0071] S12. Take 10 parts by mass of amino resin, 8 parts by mass of ethylene glycol monobutyl ether, and 0.1 part by mass of dodecyl mercaptan, mix and stir for 1 h, add the 50 parts by mass of acrylate emulsion, continue to stir for 2 h, add 0.1 part by mass of Degussa 902W defoamer, 0.2 part by mass of Disparlon AQ - 7180, and 30 parts by mass of deionized water, and adjust the pH to 8 to obtain the aqueous acrylic - amino resin emulsion.

[0072] Comparative Example 3

[0073] The difference from Example 1 is that the preparation of the aqueous acrylic - amino resin emulsion includes the following steps:

[0074] S11. Add 100 parts by mass of deionized water, 2 parts by mass of emulsifier, and 20 parts by mass of glycidyl versatate into a reaction kettle under a nitrogen atmosphere, stir for 1 h, heat up to 80 °C, add 20 parts by mass of methyl methacrylate, 20 parts by mass of butyl acrylate, and 0.2 part by mass of potassium persulfate, stir for 2 h, then continue to add 100 parts by mass of deionized water, 1 part by mass of emulsifier, 20 parts by mass of methyl methacrylate, 40 parts by mass of butyl acrylate, and 0.15 part by mass of potassium persulfate, stir for 1 h, add 7 parts by mass of methacrylic acid and 7 parts by mass of 2 - hydroxyethyl acrylate, stir for 1 h, heat up to 86 °C, keep warm for 1 h, adjust the pH to 5, filter, and discharge to obtain an acrylate emulsion; the emulsifier is non - ionic reactive emulsifier SM - JR - 2;

[0075] S12. Take 10 parts by mass of amino resin, 8 parts by mass of ethylene glycol butyl ether, and 0.1 part by mass of dodecyl mercaptan, mix them, stir for 1 h, add the 50 parts by mass of acrylate emulsion, continue to stir for 2 h, add 0.1 part by mass of Degussa 902W defoamer, 0.2 part by mass of Disparlon AQ-7180, and 30 parts by mass of deionized water, and adjust the pH to 8 to obtain the aqueous acrylic-amino resin emulsion.

[0076] Comparative Example 4

[0077] The difference from Example 1 is that the preparation of the aqueous acrylic-amino resin emulsion includes the following steps:

[0078] S11. Add 100 parts by mass of deionized water and 2 parts by mass of a composite emulsifier to a reaction kettle under a nitrogen atmosphere, stir for 1 h, heat up to 80 °C, add 20 parts by mass of methyl methacrylate, 20 parts by mass of butyl acrylate, and 0.2 part by mass of potassium persulfate, stir for 2 h, continue to add 100 parts by mass of deionized water, 1 part by mass of the composite emulsifier, 20 parts by mass of methyl methacrylate, 40 parts by mass of butyl acrylate, and 0.15 part by mass of potassium persulfate, stir for 1 h, add 7 parts by mass of methacrylic acid and 7 parts by mass of 2-hydroxyethyl acrylate, stir for 1 h, heat up to 86 °C, keep warm for 1 h, adjust the pH to 5, filter, and discharge to obtain the acrylate emulsion; the composite emulsifier consists of 4 parts by mass of allyloxy nonylphenol polyoxyethylene (10) ether ammonium sulfate and 1 part by mass of nonionic reactive emulsifier SM-JR-2;

[0079] S12. Take 10 parts by mass of amino resin, 8 parts by mass of ethylene glycol butyl ether, and 0.1 part by mass of dodecyl mercaptan, mix them, stir for 1 h, add the 50 parts by mass of acrylate emulsion, continue to stir for 2 h, add 0.1 part by mass of Degussa 902W defoamer, 0.2 part by mass of Disparlon AQ-7180, and 30 parts by mass of deionized water, and adjust the pH to 8 to obtain the aqueous acrylic-amino resin emulsion.

[0080] Comparative Example 5

[0081] The difference from Example 1 is that:

[0082] S3. Take 2-(p-dodecyloxyphenyl)pyrazine-5-carboxylic acid, chromium hydroxide, and a sulfuric acid solution with a concentration of 1 mol / L, mix them, stir in a water bath at 80 °C for 2 h, add deionized water, ultrasonically disperse for 1 h, and spray onto the surface of the aluminum paint at a spraying speed of 120 mL / min; during the spraying process, the aluminum paint is continuously stirred at a stirring speed of 500 r / min to obtain the environmentally friendly waterborne corrosion-resistant metal baking paint;

[0083] The dosage ratio of 2-(p-dodecyloxyphenyl)pyrazine-5-carboxylic acid, chromium hydroxide, sulfuric acid solution, deionized water, and aluminum paint is 10 g: 5 g: 100 mL: 500 mL: 90 g.

[0084] Comparative Example 6

[0085] The difference from Example 1 is that:

[0086] S3. Take 2-(p-dodecyloxyphenyl)pyrazine-5-carboxylic acid and mix it with a sulfuric acid solution with a concentration of 1 mol / L, stir in a water bath at 80 °C for 2 h, add potassium chromate and deionized water, ultrasonically disperse for 1 h, and spray it on the surface of the aluminum paint at a spraying speed of 120 mL / min; during the spraying process, the aluminum paint is continuously stirred at a stirring speed of 500 r / min to obtain the environmentally friendly waterborne corrosion-resistant metal baking paint.

[0087] The dosage ratio of 2-(p-dodecyloxyphenyl)pyrazine-5-carboxylic acid, sulfuric acid solution, potassium chromate, deionized water, and aluminum paint is 10 g: 100 mL: 6 g: 500 mL: 90 g.

[0088] Performance Test

[0089] Take the metal baking paints prepared in Examples 1-3 and Comparative Examples 1-6 for painting, including the following steps: Take untreated aluminum plates (length × width × height = 20 cm × 10 cm × 3 cm), wipe the surface of the aluminum plates with isopropyl alcohol, spray the above metal baking paint onto the surface of the treated aluminum plates with a spray gun, the pelvic air pressure is 500 kPa, the spraying gun distance is 400 mm, the film thickness is 5 mm, the spraying environment temperature is (25 ± 2) °C, the relative humidity is 50%, after spraying, place it in the room for flash drying for 15 min, then put it in an oven at 160 °C for baking for 10 min, and take it out and cool to obtain the paint film.

[0090] The paint films prepared in Examples 1-3 and Comparative Examples 1-6 above were tested according to the standard GB / T 10125-1997 "Artificial Atmosphere Corrosion Test - Salt Spray Test", and the test results are shown in Table 1 below.

[0091] Table 1

[0092]

[0093]

[0094] As can be seen from Table 1, the metal baking varnishes prepared in Examples 1-3 have good corrosion resistance; for the metal baking varnishes of Comparative Examples 1-6 prepared on the basis of Example 1, among them, in Comparative Example 1, monomers were emulsified in one step during the preparation process, resulting in poor stability of the prepared waterborne acrylic-aminoresin emulsion and poor corrosion resistance after film formation; in the preparation processes of Comparative Examples 2-3, only a single emulsifier was added, resulting in easy migration of the emulsifier in the prepared waterborne acrylic-aminoresin emulsion and poor corrosion resistance after film formation; in Comparative Example 4, glycidyl versatate was not added during the preparation process, resulting in a reduction in the steric hindrance of the prepared waterborne acrylic-aminoresin emulsion, easy hydrolysis of the emulsion, and poor corrosion resistance after film formation; in the preparation processes of Comparative Examples 5-6, trivalent chromium ions and hexavalent chromium ions were not introduced to support and fill the pores between the paint films, resulting in poor corrosion resistance after film formation.

[0095] The above are only the preferred embodiments of the present invention and do not impose any formal limitations on the present invention. Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or equivalent changes and modifications within the scope of the technical solution of the present invention. However, as long as it does not depart from the technical solution content of the present invention, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A preparation method of an environmentally friendly waterborne corrosion-resistant metal baking paint, characterized in that, It includes the following steps: S1. Mix dipropylene glycol methyl ether and dipropylene glycol butyl ether, stir for 20 - 30 min, add them to the aqueous acrylic - amino resin emulsion under stirring, mix at a rotation speed of 500 - 600 r / min for 5 - 8 min, then add N,N - dimethylethanolamine with a mass fraction of 10%, mix at a rotation speed of 500 - 600 r / min for 5 - 6 min, add deionized water, continue to mix at a rotation speed of 500 - 600 r / min for 5 - 6 min, add a silver - discharging aid, mix at a rotation speed of 600 - 800 r / min for 5 - 6 min to obtain a varnish; S2. Take aluminum powder and place it in a stirring kettle, add ethylene glycol monobutyl ether, stir for 20 - 30 min, let it stand for 1 - 2 h to obtain a pre - dispersed slurry, mix the pre - dispersed slurry and the varnish, stir for 15 - 30 min to obtain an aluminum paint; S3. Mix 2 - (p - dodecyloxyphenyl)pyrazine - 5 - carboxylic acid, chromium hydroxide, and sulfuric acid solution, stir in a water bath at 80 - 90 °C for 2 - 3 h, add potassium chromate and deionized water, ultrasonically disperse for 1 - 2 h, and spray it on the surface of the aluminum paint at a spraying speed of 120 mL / min; during the spraying process, the aluminum paint is continuously stirred at a stirring speed of 500 - 600 r / min to obtain the environmentally friendly water - borne corrosion - resistant metal baking paint; In step S3, the dosage ratio of 2 - (p - dodecyloxyphenyl)pyrazine - 5 - carboxylic acid, chromium hydroxide, sulfuric acid solution, potassium chromate, deionized water, and aluminum paint is 10 - 20 g: 5 - 8 g: 100 mL: 6 - 8 g: 500 mL: 90 - 100 g; The preparation of the aqueous acrylic - amino resin emulsion includes the following steps: S11. Add deionized water, a composite emulsifier, and glycidyl versatate to a reaction kettle under a nitrogen atmosphere, stir for 1 - 2 h, heat up to 80 °C, add methyl methacrylate, butyl acrylate, and potassium persulfate, stir for 2 - 3 h, continue to add deionized water, a composite emulsifier, methyl methacrylate, butyl acrylate, and potassium persulfate, stir for 1 - 2 h, add methacrylic acid and 2 - hydroxyethyl acrylate, stir for 1 - 2 h, heat up to 86 °C, keep warm for 1 - 2 h, adjust the pH to 5 - 6, filter, and discharge to obtain an acrylate emulsion; S12. Take an amino resin, ethylene glycol monobutyl ether, and dodecyl mercaptan, stir for 1 - 2 h, add the acrylate emulsion, continue to stir for 2 - 4 h, add an antifoaming agent, a leveling agent, and deionized water, adjust the pH to 8 - 9 to obtain the aqueous acrylic - amino resin emulsion; The composite emulsifier is composed of an anionic reactive emulsifier and a non - ionic reactive emulsifier; The mass ratio of the anionic reactive emulsifier to the non - ionic reactive emulsifier is 4: 1 - 1.5; The anionic reactive emulsifier is ammonium allyloxynonylphenol polyoxyethylene (10) ether sulfate; the non - ionic reactive emulsifier is non - ionic reactive emulsifier SM - JR - 2.

2. The preparation method of an environmentally friendly waterborne corrosion-resistant metal baking paint according to claim 1, characterized in that, In step S1, the mass ratio of dipropylene glycol methyl ether, dipropylene glycol butyl ether, waterborne acrylic-amino resin emulsion, N,N-dimethylethanolamine, deionized water, and silver plating aid is 3-5: 2-3: 40-60: 4-6: 20-30: 10-20.

3. The preparation method of an environmentally friendly water-based corrosion-resistant metal baking paint according to claim 1, characterized in that, In step S2, the mass ratio of aluminum powder, ethylene glycol butyl ether, and varnish is 6-8: 7-9: 80-100.

4. The preparation method of an environmentally friendly waterborne corrosion-resistant metal baking paint according to claim 1, characterized in that, In step S11, the mass ratio of deionized water added for the first time, composite emulsifier added for the first time, glycidyl versatate, methyl methacrylate added for the first time, butyl acrylate added for the first time, potassium persulfate added for the first time, deionized water added for the second time, composite emulsifier added for the second time, methyl methacrylate added for the second time, butyl acrylate added for the second time, potassium persulfate added for the second time, methacrylic acid, and 2-hydroxyethyl acrylate is 100: 2-4: 20-25: 20-25: 20-25: 0.2-0.3: 100: 1-2: 20-25: 40-50: 0.15-0.25: 7-8: 7-8.

5. The preparation method of an environmentally friendly waterborne corrosion-resistant metal baking paint according to claim 1, characterized in that, In step S12, the mass ratio of amino resin, ethylene glycol butyl ether, dodecyl mercaptan, acrylate emulsion, defoamer, leveling agent, and deionized water is 10-20: 8-10: 0.1-0.15: 50-65: 0.1-0.2: 0.2-0.3: 30-40.

6. An environmentally friendly waterborne corrosion-resistant metal baking paint prepared by the preparation method of the environmentally friendly waterborne corrosion-resistant metal baking paint according to any one of claims 1-5.

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