Waterborne coating based on polyurethane acrylic emulsion and preparation method thereof

Abstract

The invention relates to the technical field of anticorrosive paint, and discloses a water-based coating based on polyurethane acrylic emulsion and a preparation method of the water-based coating. The water-based coating comprises a component A and a component B. The component A comprises the following raw materials in parts by weight: 50-70 parts of modified acrylic resin, 0.3-0.6 part of a defoaming agent, 0.5-1.5 parts of a dispersing agent, 3.5-6.5 parts of a coalescing agent, 1-2 parts of a thickening agent, 0.2-0.5 part of triethylamine and 15-25 parts of water. The component B is prepared from the following raw materials in parts by weight: 70 to 80 parts of isocyanate and 35 to 45 parts of propylene glycol diacetate; the coating combines the double advantages of the acrylic emulsion and the polyurethane emulsion, has excellent adhesive force, flexibility, wear resistance and corrosion resistance, and can be widely applied to the fields of ships, pipelines, automobiles, bridges and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of anticorrosive coatings, and particularly relates to an aqueous coating based on polyurethane acrylate emulsion and a preparation method thereof. Background Art

[0002] In the fields of industrial anti-corrosion, ocean engineering, automobile manufacturing, etc., the corrosion protection of metal materials has always been a core technical challenge. Traditional solvent-based coatings (such as epoxy resins, alkyd resins, etc.) rely on organic solvents (benzene, esters, etc.) as dispersion media. Although they have good film-forming properties and chemical resistance, their high volatile organic compound (VOC) emissions cause serious harm to the environment and human health. With the increasingly strict global environmental protection regulations, the development of low-VOC and high-performance aqueous coatings has become an urgent need in the industry.

[0003] Early aqueous coatings (such as pure acrylic emulsion or pure aqueous polyurethane emulsion) are difficult to meet the requirements of high-corrosion-resistant scenarios due to the following defects: (1) Insufficient mechanical properties: low hardness and poor wear resistance, and it is difficult to withstand mechanical wear or impact; (2) Limited chemical resistance: weak long-term resistance to media such as acids, alkalis, and salt spray; (3) Insufficient adhesion and denseness: pores are easily formed in the coating, resulting in the penetration of corrosive media to the substrate surface. Therefore, in view of the problems existing in early aqueous coatings, it is necessary to develop an aqueous coating that has excellent corrosion resistance, adhesion, and mechanical properties after coating and drying. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides an aqueous coating based on polyurethane acrylate emulsion and a preparation method thereof.

[0005] The object of the present invention can be achieved by the following technical solutions:

[0006] An aqueous coating based on polyurethane acrylate emulsion, wherein the aqueous coating is prepared by blending component A and component B, and the mass ratio of component A to component B is 80 - 100:30 - 40;

[0007] Component A includes the following raw materials by weight: 50 - 70 parts of modified acrylic resin, 0.3 - 0.6 part of defoamer, 0.5 - 1.5 parts of dispersant, 3.5 - 6.5 parts of film-forming aid, 1 - 2 parts of thickener, 0.2 - 0.5 part of triethylamine, and 15 - 25 parts of water;

[0008] Further, the defoamer in component A is defoamer BYK - 011, the dispersant is dispersant BYK - 190, the film-forming aid is propylene glycol methyl ether, and the thickener is hydroxymethyl cellulose;

[0009] Component B includes the following raw materials by weight: 70 - 80 parts of isocyanate and 35 - 45 parts of propylene glycol diacetate;

[0010] Further, the isocyanate in component B is one of toluene diisocyanate, hexamethylene diisocyanate and isophorone diisocyanate;

[0011] The modified acrylic resin is prepared by the following steps:

[0012] Step A1: Heat water and emulsifier SE-10N to 120 °C in an oil bath, and then slowly add methyl methacrylate, butyl acrylate, hydroxypropyl methacrylate, hydroxyethyl methacrylate, acrylic acid and glycidyl methacrylate to form a pre-emulsion; slowly drip the pre-emulsion into 4 / 5 volume of tert-butyl peroxybenzoate aqueous solution, control the dripping speed at 1 drop / s, the total dripping time is 2 h, after the dripping is completed, add the remaining tert-butyl peroxybenzoate aqueous solution, and raise the temperature to 80-90 °C and react for 2-3 h, cool and filter to obtain acrylic resin;

[0013] Further, in the pre-emulsion of step A1, the mass ratio of water, emulsifier SE-10N, methyl methacrylate, butyl acrylate, hydroxypropyl methacrylate, hydroxyethyl methacrylate, acrylic acid and glycidyl methacrylate is 60:2-3:15-25:8-12:5-10:3-6:1-2:1.5-3.5;

[0014] Further, in step A1, the tert-butyl peroxybenzoate aqueous solution is prepared by mixing tert-butyl peroxybenzoate and water at a mass ratio of 0.1-0.3:50 and stirring;

[0015] Step A2: Heat the acrylic resin to 70 °C and stir for 10 min, then add modified lignin and tetrabutylammonium bromide DMF (N,N-dimethylformamide) solution, and raise the temperature to 90 °C and stir and react for 3-5 h, rotary evaporate to obtain lignin / acrylic resin;

[0016] Further, in step A2, the dosage ratio of acrylic resin, modified lignin and tetrabutylammonium bromide DMF solution is 8-12 g:1.5-3.5 g:20 mL;

[0017] Further, in step A2, the tetrabutylammonium bromide DMF solution is prepared by mixing tetrabutylammonium bromide and DMF at a dosage ratio of 0.3-0.6 g:20 mL and stirring;

[0018] Step A3: Ultrasonically disperse KH580-modified manganese dioxide nanosheets in water, adjust the pH to 10, add lignin / acrylic resin and triethylamine aqueous solution, raise the temperature to 75-85 °C, stir and react for 8 h, filter and dry to obtain the modified acrylic resin;

[0019] Further, in step A3, the dosage ratio of the KH580-modified manganese dioxide nanosheets, water, lignin / acrylic resin, and triethylamine aqueous solution is 0.2 - 0.6 g:50 mL:10 - 15 g:5 mL;

[0020] Further, in step A3, the triethylamine aqueous solution is composed of triethylamine and water at a ratio of 0.005 - 0.02 g:5 mL.

[0021] The modified lignin is prepared by the following steps:

[0022] Step B1: Disperse 3-chloropropylamine hydrochloride and sodium hydroxide evenly in DMF, add 2-methylimidazoline and stir for reaction for 24 h, perform rotary evaporation and purification to obtain aminoimidazoline;

[0023] Further, in step B1, the molar ratio of 3-chloropropylamine hydrochloride to 2-methylimidazoline is 1.05 - 1.2:1;

[0024] Further, in step B1, the dosage of sodium hydroxide is 40% - 60% of the mass of 3-chloropropylamine hydrochloride;

[0025] Step B2: Mix aminoimidazoline and DMF evenly, add 1,4-dibromobutane and heat to 45 - 55 °C, stir for reaction for 5 - 7 h, then add N-vinylimidazole, maintain the temperature and continue the reaction for 6 - 8 h, perform rotary evaporation and drying to obtain imidazoline-imidazole derivative;

[0026] Further, in step B2, the molar ratio of aminoimidazoline, 1,4-dibromobutane, and N-vinylimidazole is 1:1 - 1.03:1;

[0027] Step B3: Disperse lignin in a sodium hydroxide solution with a pH of 10.5, heat to 60 °C, then slowly add the mixed solution and stir for reaction for 3 h, filter, wash, and dry to obtain carboxylated lignin;

[0028] Further, in step B3, the dosage ratio of lignin, sodium hydroxide solution, and the mixed solution is 8 - 12 g:100 mL:62 mL;

[0029] Further, in step B3, the mixed solution is prepared by mixing 50 mL of 10 wt% sodium chloroacetate solution in 12 mL of 6 mol / L sodium hydroxide solution;

[0030] Step B4: Disperse carboxylated lignin in DMF, heat to 40 - 60 °C, add EDC (1-ethyl-(3-dimethylaminopropyl)carbodiimide) and NHS (N-hydroxysuccinimide) in sequence and stir for 2 - 3 h, then add imidazoline-imidazole derivative, stir vigorously for reaction for 3 - 4 h, filter, wash, and dry to obtain modified lignin;

[0031] Further, in step B4, the mass ratio of carboxylated lignin, DMF, EDC, NHS, and imidazoline-imidazole derivative is 5-10 g: 100 mL: 1.55-3.1 g: 0.95-1.9 g: 1.2-3.6 g.

[0032] A preparation method of an aqueous coating based on a polyurethane acrylate emulsion includes the following steps:

[0033] Step S1: Weigh raw materials by weight parts, mix and stir evenly the modified acrylic resin, defoamer, dispersant, film-forming aid, thickener, triethylamine, and water to obtain component A;

[0034] Step S2: Weigh raw materials by weight parts, mix and stir evenly the isocyanate and propylene glycol diacetate to obtain component B;

[0035] Step S3: Mix component A and component B in a mass ratio of 80-100: 30-40, stir evenly, coat the film, and dry it to obtain the aqueous coating based on the polyurethane acrylate emulsion.

[0036] Advantages of the present invention:

[0037] The aqueous coating based on the polyurethane acrylate emulsion in the present invention is prepared by mixing and stirring the modified acrylic resin, isocyanate, and various functional additives, coating the film, and drying it; this coating combines the dual advantages of acrylic emulsion and polyurethane emulsion, not only having excellent adhesion, flexibility, abrasion resistance, but also having excellent corrosion resistance. Therefore, it can be widely applied to fields such as ships, pipelines, automobiles, and bridges.

[0038] The acrylic component in the present invention is different from the way of grafting acrylate monomers at the end of polyurethane prepolymer in traditional polyurethane acrylate emulsion. Instead, it is prepared by reacting a modified acrylic resin containing multiple hydroxyl groups with isocyanate. The emulsion prepared by this method has a relatively high crosslinking structure, which improves the flexibility of the coating while also having a certain hardness. An imidazoline structure, an imidazole structure, and manganese dioxide nanosheets are also introduced into the modified acrylic resin. The synergistic effect of the three improves the corrosion resistance and adhesion of the coating. This is because the N atoms and heterocyclic structures in the imidazoline and imidazole structures have strong polarity and can adsorb on the metal surface to form a dense monomolecular protective film, isolating water, oxygen, and corrosive ions, thereby improving the corrosion resistance of the coating. At the same time, quaternization reactions are carried out on imidazoline and imidazole by substitution reactions, and a quaternary ammonium salt structure is also introduced. The quaternary ammonium salt can form a protective layer on the metal surface to prevent the corrosive medium from directly contacting the metal, thereby extending the service life of the material. The manganese dioxide nanosheets can form a tortuous penetration path in the coating to extend the diffusion time of the corrosive medium and react with the metal surface as an oxidant to induce the formation of a dense passivation film, improving the corrosion resistance of the coating through physical barrier action and chemical synergistic action. In addition, the abundant polar groups in lignin have good adsorption properties and can further improve the adhesion of the coating. Detailed implementation mode

[0039] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0040] The KH580-modified manganese dioxide nanosheets described in the following examples were all prepared by the following steps:

[0041] Disperse 5 g of manganese dioxide nanosheets in 10 mL of deionized water and 40 mL of water by ultrasonic for 50 min, add 0.5 mL of silane coupling agent KH580, and raise the temperature to 45 °C for reaction for 12 h. Filter, wash, and dry to obtain KH580-modified manganese dioxide nanosheets.

[0042] Example 1: The modified lignin was prepared by the following steps:

[0043] Step B1: Disperse 1.05 mol of 3-chloropropylamine hydrochloride and sodium hydroxide evenly in 200 mL of DMF, add 1 mol of 2-methylimidazoline and stir for reaction for 24 h. Rotate and evaporate, and purify to obtain aminoimidazoline. The dosage of sodium hydroxide is 40% of the mass of 3-chloropropylamine hydrochloride.

[0044] Step B2: Mix 1 mol of aminoimidazoline and 200 mL of DMF evenly, add 1 mol of 1,4-dibromobutane and heat up to 45 °C, stir and react for 5 h, then add 1 mol of N-vinylimidazole, maintain the temperature and continue to react for 6 h, rotary evaporate and dry to obtain imidazoline-imidazole derivative;

[0045] Step B3: Disperse 8 g of lignin in 100 mL of sodium hydroxide solution with pH 10.5, heat up to 60 °C, then slowly add 62 mL of the mixed solution and stir and react for 3 h, filter, wash and dry to obtain carboxylated lignin; the mixed solution is prepared by mixing 50 mL of 10 wt% sodium chloroacetate solution and 12 mL of 6 mol / L sodium hydroxide solution;

[0046] Step B4: Disperse 5 g of carboxylated lignin in 100 mL of DMF, heat up to 40 °C, add 1.55 g of EDC and 0.95 g of NHS in sequence and stir for 2 h, then add 1.2 g of imidazoline-imidazole derivative, stir and react vigorously for 3 h, filter, wash and dry to obtain modified lignin.

[0047] The modified acrylic resin is prepared by the following steps:

[0048] Step A1: Heat 60 g of water and 2 g of emulsifier SE-10N to 120 °C in an oil bath, then slowly add 15 g of methyl methacrylate, 8 g of butyl acrylate, 5 g of hydroxypropyl methacrylate, 3 g of hydroxyethyl methacrylate, 1 g of acrylic acid and 1.5 g of glycidyl methacrylate to form a pre-emulsion; slowly drop the pre-emulsion into 4 / 5 volume of tert-butyl peroxybenzoate aqueous solution, control the dropping speed at 1 drop / s, the total dropping time is 2 h, after the dropping is completed, add the remaining tert-butyl peroxybenzoate aqueous solution and heat up to 80 °C to react for 2 h, cool and filter to obtain acrylic resin; the tert-butyl peroxybenzoate aqueous solution is prepared by mixing tert-butyl peroxybenzoate and water in a ratio of 0.1 g:50 g and stirring;

[0049] Step A2: Heat 8 g of acrylic resin to 70 °C and stir for 10 min, then add 1.5 g of modified lignin and 20 mL of tetrabutylammonium bromide DMF solution, and heat up to 90 °C to stir and react for 3 h, rotary evaporate to obtain lignin / acrylic resin, the tetrabutylammonium bromide DMF solution is prepared by mixing tetrabutylammonium bromide and DMF in a dosage ratio of 0.3 g:20 mL and stirring;

[0050] Step A3: Ultrasonically disperse 0.2 g of KH580-modified manganese dioxide nanosheets in 50 mL of water, adjust the pH to 10, add 10 g of lignin / acrylic resin and 5 mL of triethylamine aqueous solution, heat to 75 °C, stir and react for 8 h, filter and dry to obtain the modified acrylic resin. The triethylamine aqueous solution is prepared from triethylamine and water at a ratio of 0.005 g:5 mL.

[0051] Example 2: The modified lignin is prepared by the following steps:

[0052] Step B1: Disperse 1.1 mol of 3-chloropropylamine hydrochloride and sodium hydroxide evenly in 200 mL of DMF, add 1 mol of 2-methylimidazoline and stir and react for 24 h, rotary evaporate and purify to obtain aminoimidazoline. The dosage of sodium hydroxide is 50% of the mass of 3-chloropropylamine hydrochloride;

[0053] Step B2: Mix 1 mol of aminoimidazoline and 200 mL of DMF evenly, add 1.02 mol of 1,4-dibromobutane and heat to 50 °C, stir and react for 6 h, then add 1 mol of N-vinylimidazole, maintain the temperature and continue to react for 7 h, rotary evaporate and dry to obtain imidazoline-imidazole derivative;

[0054] Step B3: Disperse 10 g of lignin in 100 mL of sodium hydroxide solution with a pH of 10.5, heat to 60 °C, and slowly add 62 mL of the mixed solution and stir and react for 3 h, filter, wash and dry to obtain carboxylated lignin; the mixed solution is prepared by mixing 50 mL of 10 wt% sodium chloroacetate solution in 12 mL of 6 mol / L sodium hydroxide solution;

[0055] Step B4: Disperse 7.5 g of carboxylated lignin in 100 mL of DMF, heat to 50 °C, add 2.3 g of EDC and 1.4 g of NHS in sequence and stir for 2.5 h, then add 2.4 g of imidazoline-imidazole derivative, stir vigorously and react for 3.5 h, filter, wash and dry to obtain the modified lignin.

[0056] The modified acrylic resin is prepared by the following steps:

[0057] Step A1: Heat 60 g of water and 2.5 g of emulsifier SE-10N to 120 °C in an oil bath, and then slowly add 20 g of methyl methacrylate, 10 g of butyl acrylate, 7.5 g of hydroxypropyl methacrylate, 4.5 g of hydroxyethyl methacrylate, 1.5 g of acrylic acid, and 2.5 g of glycidyl methacrylate to form a pre-emulsion; slowly drop the pre-emulsion into 4 / 5 volume of tert-butyl perbenzoate aqueous solution, control the dropping rate at 1 drop / s, and the total dropping time is 2 h. After the dropping is completed, add the remaining tert-butyl perbenzoate aqueous solution, and raise the temperature to 85 °C and react for 2.5 h. Cool and filter to obtain the acrylic resin; the tert-butyl perbenzoate aqueous solution is prepared by mixing and stirring tert-butyl perbenzoate and water at a ratio of 0.2 g:50 g;

[0058] Step A2: Heat 10 g of acrylic resin to 70 °C and stir for 10 min, then add 2.5 g of modified lignin and 20 mL of tetrabutylammonium bromide DMF solution, and raise the temperature to 90 °C and stir and react for 4 h. Rotate and evaporate to obtain the lignin / acrylic resin. The tetrabutylammonium bromide DMF solution is prepared by mixing and stirring tetrabutylammonium bromide and DMF at a dosage ratio of 0.45 g:20 mL;

[0059] Step A3: Ultrasonically disperse 0.4 g of KH580-modified manganese dioxide nanosheets in 50 mL of water, adjust the pH to 10, add 12.5 g of lignin / acrylic resin and 5 mL of triethylamine aqueous solution, raise the temperature to 80 °C, stir and react for 8 h, filter and dry to obtain the modified acrylic resin. The triethylamine aqueous solution is prepared by mixing triethylamine and water at a ratio of 0.01 g:5 mL.

[0060] Example 3: The modified lignin is prepared by the following steps:

[0061] Step B1: Disperse 1.2 mol of 3-chloropropylamine hydrochloride and sodium hydroxide evenly in 200 mL of DMF, add 1 mol of 2-methylimidazoline and stir and react for 24 h. Rotate and evaporate and purify to obtain the aminoimidazoline. The dosage of sodium hydroxide is 60% of the mass of 3-chloropropylamine hydrochloride;

[0062] Step B2: Mix 1 mol of aminoimidazoline and 200 mL of DMF evenly, add 1.03 mol of 1,4-dibromobutane and raise the temperature to 55 °C, stir and react for 7 h, then add 1 mol of N-vinylimidazole, and maintain the temperature and continue to react for 8 h. Rotate and evaporate and dry to obtain the imidazoline-imidazole derivative;

[0063] Step B3: Disperse 12 g of lignin in 100 mL of sodium hydroxide solution with a pH of 10.5, heat up to 60 °C, then slowly add 62 mL of the mixed solution and stir for 3 h, filter, wash, and dry to obtain carboxylated lignin; the mixed solution is prepared by mixing 50 mL of 10 wt% sodium chloroacetate solution in 12 mL of 6 mol / L sodium hydroxide solution;

[0064] Step B4: Disperse 10 g of carboxylated lignin in 100 mL of DMF, heat up to 60 °C, add 3.1 g of EDC and 1.9 g of NHS in sequence and stir for 3 h, then add 3.6 g of imidazoline-imidazole derivative, stir vigorously for 4 h, filter, wash, and dry to obtain modified lignin.

[0065] The modified acrylic resin is prepared by the following steps:

[0066] Step A1: Heat 60 g of water and 3 g of emulsifier SE-10N to 120 °C in an oil bath, then slowly add 25 g of methyl methacrylate, 12 g of butyl acrylate, 10 g of hydroxypropyl methacrylate, 6 g of hydroxyethyl methacrylate, 2 g of acrylic acid, and 3.5 g of glycidyl methacrylate to form a pre-emulsion; slowly drop the pre-emulsion into 4 / 5 volume of tert-butyl peroxybenzoate aqueous solution, control the dropping rate at 1 drop / s, with a total dropping time of 2 h, after the dropping is completed, add the remaining tert-butyl peroxybenzoate aqueous solution and heat up to 90 °C for reaction for 3 h, cool and filter to obtain acrylic resin; the tert-butyl peroxybenzoate aqueous solution is prepared by mixing tert-butyl peroxybenzoate and water in a ratio of 0.3 g:50 g and stirring;

[0067] Step A2: Heat 12 g of acrylic resin to 70 °C and stir for 10 min, then add 3.5 g of modified lignin and 20 mL of tetrabutylammonium bromide DMF solution, and heat up to 90 °C and stir for 5 h, rotary evaporate to obtain lignin / acrylic resin, the tetrabutylammonium bromide DMF solution is prepared by mixing tetrabutylammonium bromide and DMF in a dosage ratio of 0.6 g:20 mL and stirring;

[0068] Step A3: Ultrasonically disperse 0.6 g of KH580-modified manganese dioxide nanosheets in 50 mL of water, adjust the pH to 10, add 15 g of lignin / acrylic resin and 5 mL of triethylamine aqueous solution, heat up to 85 °C, stir for 8 h, filter and dry to obtain the modified acrylic resin, the triethylamine aqueous solution is prepared by mixing triethylamine and water in a ratio of 0.02 g:5 mL.

[0069] Example 4: A preparation method of an aqueous coating based on polyurethane acrylate emulsion includes the following steps:

[0070] Step S1: Weigh the raw materials by parts by weight. Mix 50 parts of the modified acrylic resin prepared in Example 1, 0.3 part of defoamer BYK-011, 0.5 part of dispersant BYK-190, 3.5 parts of propylene glycol methyl ether, 1 part of hydroxymethyl cellulose, 0.2 part of triethylamine, and 15 parts of water and stir evenly to obtain Component A;

[0071] Step S2: Weigh the raw materials by parts by weight. Mix 70 parts of toluene diisocyanate and 35 parts of propylene glycol diacetate and stir evenly to obtain Component B;

[0072] Step S3: Mix Component A and Component B in a mass ratio of 80:30, stir evenly, coat the film, and dry it to obtain the water-based coating based on polyurethane acrylate emulsion.

[0073] Example 5: A method for preparing a water-based coating based on polyurethane acrylate emulsion includes the following steps:

[0074] Step S1: Weigh the raw materials by parts by weight. Mix 60 parts of the modified acrylic resin prepared in Example 2, 0.45 part of defoamer BYK-011, 1 part of dispersant BYK-190, 4 parts of propylene glycol methyl ether, 1.5 parts of hydroxymethyl cellulose, 0.3 part of triethylamine, and 20 parts of water and stir evenly to obtain Component A;

[0075] Step S2: Weigh the raw materials by parts by weight. Mix 75 parts of hexamethylene diisocyanate and 40 parts of propylene glycol diacetate and stir evenly to obtain Component B;

[0076] Step S3: Mix Component A and Component B in a mass ratio of 90:35, stir evenly, coat the film, and dry it to obtain the water-based coating based on polyurethane acrylate emulsion.

[0077] Example 6: A method for preparing a water-based coating based on polyurethane acrylate emulsion includes the following steps:

[0078] Step S1: Weigh the raw materials by parts by weight. Mix 70 parts of the modified acrylic resin prepared in Example 3, 0.6 part of defoamer BYK-011, 1.5 part of dispersant BYK-190, 6.5 parts of propylene glycol methyl ether, 2 parts of hydroxymethyl cellulose, 0.5 part of triethylamine, and 25 parts of water and stir evenly to obtain Component A;

[0079] Step S2: Weigh the raw materials by parts by weight. Mix 80 parts of isophorone diisocyanate and 45 parts of propylene glycol diacetate and stir evenly to obtain Component B;

[0080] Step S3: Mix Component A and Component B in a mass ratio of 100:40, stir evenly, coat the film, and dry it to obtain the water-based coating based on polyurethane acrylate emulsion.

[0081] Comparative Example 1: This comparative example is a waterborne coating, which is different from Example 6 in that a commercially available hydroxyl acrylic resin is used instead of the modified acrylic resin prepared in Example 3, and the rest are the same.

[0082] Comparative Example 2: This comparative example is a waterborne coating, which is different from Example 6 in that the lignin / acrylic resin prepared in Example 3 is used instead of the modified acrylic resin prepared in Example 3, and the rest are the same.

[0083] Perform performance tests on the waterborne coatings prepared in Examples 4 - 6 and Comparative Examples 1 - 2:

[0084] Impact resistance test: The test is carried out with reference to the standard of GB / T 1732 - 2020;

[0085] Corrosion resistance test: The test is carried out with reference to the standard of GB / T 9274 - 1988. Immerse the sample film in 5wt% H2SO4 solution, 5wt% NaOH solution and 3wt% saline for 1000h, and observe the surface condition of the coating;

[0086] Adhesion test: The test is carried out with reference to "GB9286—88 Cross - cut Test for Paint and Varnish Films";

[0087] The test results are shown in Table 1:

[0088] Table 1: Performance test results

[0089]

[0090] As can be seen from Table 1, after the waterborne coatings prepared by the present invention are tested for impact resistance, corrosion resistance and adhesion, the impact resistance height is ≥50 (cm). When immersed in 5wt% sulfuric acid solution, 5wt% sodium hydroxide solution and 3wt% saline respectively, there is no abnormality in the coating, and the adhesion grade is all Grade 1, indicating that the coating has excellent corrosion resistance, impact resistance and adhesion.

[0091] The above content is only an example and explanation of the concept of the present invention. Those skilled in the art of this technology can make various modifications, supplements or use similar methods to replace the specific embodiments described, as long as they do not deviate from the scope defined by the concept of the invention, they should all fall within the protection scope of the present invention.

Claims

1. An aqueous coating based on polyurethane acrylate emulsion, characterized in that, The aqueous coating is prepared by blending component A and component B, and the mass ratio of component A to component B is 80 - 100:30 - 40; Component A includes the following raw materials by weight parts: 50 - 70 parts of modified acrylic resin, 0.3 - 0.6 parts of defoamer, 0.5 - 1.5 parts of dispersant, 3.5 - 6.5 parts of film-forming assistant, 1 - 2 parts of thickener, 0.2 - 0.5 parts of triethylamine, and 15 - 25 parts of water; Component B includes the following raw materials by weight parts: 70 - 80 parts of isocyanate and 35 - 45 parts of propylene glycol diacetate; The modified acrylic resin is prepared by reacting manganese dioxide nanosheets modified with KH580 and lignin / acrylic resin. The lignin / acrylic resin is prepared by reacting acrylic resin and modified lignin. The acrylic resin is prepared by polymerizing acrylate monomers through an initiator; The modified lignin is prepared by reacting carboxylated lignin and imidazoline-imidazole derivative. The imidazoline-imidazole derivative is prepared by reacting aminoimidazoline, 1,4-dibromobutane and N-vinylimidazole. The aminoimidazoline is prepared by reacting 3-chloropropylamine hydrochloride and 2-methylimidazoline.

2. The water-based coating based on polyurethane acrylate emulsion according to claim 1, characterized in that, The modified acrylic resin is prepared by the following steps: Step A1: Heat water and emulsifier SE-10N to 120 °C in an oil bath, and then slowly add methyl methacrylate, butyl acrylate, hydroxypropyl methacrylate, hydroxyethyl methacrylate, acrylic acid and glycidyl methacrylate to form a pre-emulsion; slowly drop the pre-emulsion into 4 / 5 volume of tert-butyl peroxybenzoate aqueous solution, and control the dropping rate at 1 drop / s, with a total dropping time of 2 h. After the dropping is completed, add the remaining tert-butyl peroxybenzoate aqueous solution and raise the temperature to 80 - 90 °C for reaction for 2 - 3 h, cool and filter to obtain acrylic resin; Step A2: Raise the temperature of the acrylic resin to 70 °C and stir for 10 min, then add modified lignin and tetrabutylammonium bromide DMF solution, and raise the temperature to 90 °C and stir for reaction for 3 - 5 h, and perform rotary evaporation to obtain lignin / acrylic resin; Step A3: Ultrasonically disperse manganese dioxide nanosheets modified with KH580 in water, adjust the pH to 10, add lignin / acrylic resin and triethylamine aqueous solution, raise the temperature to 75 - 85 °C, stir for reaction for 8 h, filter and dry to obtain modified acrylic resin.

3. The aqueous coating based on polyurethane acrylate emulsion according to claim 2, wherein, In the pre-emulsion of step A1, the mass ratio of water, emulsifier SE-10N, methyl methacrylate, butyl acrylate, hydroxypropyl methacrylate, hydroxyethyl methacrylate, acrylic acid and glycidyl methacrylate is 60:2 - 3:15 - 25:8 - 12:5 - 10:3 - 6:1 - 2:1.5 - 3.

5. The tert-butyl peroxybenzoate aqueous solution is prepared by mixing tert-butyl peroxybenzoate and water at a mass ratio of 0.1 - 0.3:50 and stirring.

4. The water-based coating based on polyurethane acrylate emulsion according to claim 2, wherein, In step A2, the dosage ratio of the acrylic resin, the modified lignin, and the tetrabutylammonium bromide DMF solution is 8 - 12 g : 1.5 - 3.5 g : 20 mL. The tetrabutylammonium bromide DMF solution is prepared by mixing tetrabutylammonium bromide and DMF in a dosage ratio of 0.3 - 0.6 g : 20 mL and stirring.

5. The aqueous coating based on polyurethane acrylate emulsion according to claim 2, wherein In step A3, the dosage ratio of the KH580 - modified manganese dioxide nanosheets, water, lignin / acrylic resin, and triethylamine aqueous solution is 0.2 - 0.6 g : 50 mL : 10 - 15 g : 5 mL.

6. The water-based coating based on polyurethane acrylate emulsion according to claim 1, wherein, The modified lignin is prepared by the following steps: Step B1: Disperse 3 - chloropropylamine hydrochloride and sodium hydroxide evenly in DMF, add 2 - methylimidazoline and stir - react for 24 h, then perform rotary evaporation and purification to obtain amino - imidazoline. Step B2: Mix the amino - imidazoline and DMF evenly, add 1,4 - dibromobutane and heat up to 45 - 55 °C, stir - react for 5 - 7 h, then add N - vinylimidazole, maintain the temperature and continue to react for 6 - 8 h, perform rotary evaporation and drying to obtain imidazoline - imidazole derivative. Step B3: Disperse 8 - 12 g of lignin in 100 mL of sodium hydroxide solution with a pH of 10.5, heat up to 60 °C, then slowly add 62 mL of the mixed solution and stir - react for 3 h, filter, wash, and dry to obtain carboxylated lignin. The mixed solution is prepared by mixing 50 mL of 10 wt% sodium chloroacetate solution and 12 mL of 6 mol / L sodium hydroxide solution. Step B4: Disperse the carboxylated lignin in DMF, heat up to 40 - 60 °C, sequentially add EDC and NHS and stir for 2 - 3 h, then add the imidazoline - imidazole derivative, stir - react vigorously for 3 - 4 h, filter, wash, and dry to obtain the modified lignin.

7. The water-based coating based on polyurethane acrylate emulsion according to claim 6, wherein In step B1, the molar ratio of 3 - chloropropylamine hydrochloride to 2 - methylimidazoline is 1.05 - 1.2 :

1.

8. An aqueous coating based on polyurethane acrylate emulsion according to claim 6, wherein, In step B2, the molar ratio of amino - imidazoline, 1,4 - dibromobutane, and N - vinylimidazole is 1 : 1 - 1.03 :

1.

9. The aqueous coating based on polyurethane acrylate emulsion according to claim 6, wherein, In step B4, the mass ratio of carboxylated lignin, DMF, EDC, NHS, and imidazoline - imidazole derivative is 5 - 10 g : 100 mL : 1.55 - 3.1 g : 0.95 - 1.9 g : 1.2 - 3.6 g.

10. A method for preparing the aqueous coating based on polyurethane acrylate emulsion according to any one of claims 1-9, characterized in that, It includes the following steps: Step S1: Weigh the raw materials by weight parts, mix and stir evenly the modified acrylic resin, defoamer, dispersant, film - forming aid, thickener, triethylamine, and water to obtain component A. Step S2: Weigh the raw materials by weight parts, mix and stir evenly the isocyanate and propylene glycol diacetate to obtain component B. Step S3: Mix component A and component B in a mass ratio of 80 - 100 : 30 - 40, stir evenly, coat the film, and dry to obtain the water - based coating based on polyurethane acrylate emulsion.

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