A waterborne coating modified by a multifunctional composite filler and a preparation method thereof

Abstract

The present invention relates to the technical field of coating preparation, and specifically discloses a water-based coating modified with a multifunctional composite filler and a preparation method thereof. The water-based coating, by weight, comprises 80-100 parts of a modified core-shell acrylic dispersion, 5-7 parts of a multifunctional composite filler, 0.5-1 part of an antifoaming agent, 0.5-1 part of a wetting agent, 2-5 parts of a thickening agent, 1-2 parts of a film-forming aid, and 25-35 parts of deionized water. The water-based coating provided by the present invention is modified by adding an appropriate amount of a multifunctional composite filler, has excellent performance and good stability, and through optimizing the preparation process conditions of the water-based coating, the components in the water-based coating have good compatibility. The preparation method is simple to operate and suitable for industrial production.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and particularly relates to a waterborne coating modified with a multifunctional composite filler and a preparation method thereof. Background Art

[0002] With the rapid development of the automotive industry, it has driven the rapid development of automotive coatings. Automotive coatings represent the highest technical level and development direction of the coating industry. Automotive coatings play a crucial role in automotive manufacturing and maintenance. They not only provide an aesthetic appearance for automobiles, but also have a variety of practical functions. For example, automotive coatings can effectively isolate the automobile body from direct contact with air, moisture, and corrosive substances, thereby preventing the body from rusting and corroding, which is crucial for extending the service life of automobiles; high-quality automotive coatings can also resist harsh environmental factors such as ultraviolet rays, high temperatures, and humidity, and maintain the beauty and performance of the body.

[0003] Automotive coatings include waterborne automotive coatings and solvent-based automotive coatings. Traditional automotive coatings are mostly solvent-based coatings, which will emit a large amount of VOCs during use. To meet environmental protection requirements, waterborne automotive coatings have been more widely developed. With the development of automotive coatings, the functional requirements for automotive coatings are also getting higher and higher. For example, waterborne automotive topcoats require functions such as high gloss, high distinctness of image, high weather resistance, scratch resistance, and acid rain resistance. At present, the functional improvement of automotive coatings is mainly achieved by adding fillers. Currently, there are mainly the following problems when using fillers to modify automotive coatings: First, the fillers used have insufficient functionality and cannot well improve the performance of automotive coatings; second, the compatibility between the fillers and the automotive coating matrix during modification is poor, and they are prone to agglomeration in the matrix, which will affect the performance of the coatings. Therefore, how to provide a filler with good compatibility with the coating matrix and excellent functionality is the key to improving automotive coatings. Summary of the Invention

[0004] One of the technical problems to be solved by the present invention is: aiming at the deficiencies existing in the prior art, to provide a waterborne coating modified with a multifunctional composite filler, which is modified by adding an appropriate amount of the multifunctional composite filler, has excellent performance and good stability.

[0005] Another technical problem to be solved by the present invention is: to provide a preparation method of a waterborne coating modified with a multifunctional composite filler, which optimizes each process condition, enables the components in the waterborne coating to have good compatibility, the prepared coating not only has good stability and excellent performance, but also the preparation method is simple to operate and suitable for industrial production.

[0006] To solve the above technical problems, the present invention provides the following technical solutions:

[0007] In a first aspect, the present invention provides an aqueous coating modified with a multifunctional composite filler. Calculated by weight parts, it includes 80 - 100 parts of a modified core - shell acrylic dispersion, 5 - 7 parts of a multifunctional composite filler, 0.5 - 1 part of an antifoaming agent, 0.5 - 1 part of a wetting agent, 2 - 5 parts of a thickening agent, 1 - 2 parts of a film - forming auxiliary, and 25 - 35 parts of deionized water; the multifunctional composite filler is a mixture of a modified calcium - aluminum hydrotalcite material, a graft - modified graphene / boron nitride material, and a functionalized carbon black, and the mass ratio of the modified calcium - aluminum hydrotalcite material, the graft - modified graphene / boron nitride material, and the functionalized carbon black is (2 - 5):(3 - 8):(10 - 20); the inner core of the modified core - shell acrylic dispersion is nano - titanium dioxide, and the outer layer is sequentially coated with an acrylic resin and a fluorine - modified acrylic resin.

[0008] The modified calcium - aluminum hydrotalcite material is prepared by first inserting sodium dodecylbenzenesulfonate between the layers of the calcium - aluminum hydrotalcite material and then inserting acrylamide.

[0009] The graft - modified graphene / boron nitride material is prepared by intercalating graphene and boron nitride, followed by silanization treatment, and finally graft - polymerizing and modifying with methacryloyloxyethyl sulfobetaine as a monomer.

[0010] The functionalized carbon black is prepared by pretreating carbon black and then modifying it with β - cyclodextrin and ammonium glycerophosphate respectively. The ammonium glycerophosphate is prepared by an esterification reaction of glycerol and phytic acid and a complexation reaction with urea.

[0011] Preferably, the preparation method of the modified calcium - aluminum hydrotalcite material specifically includes the following steps:

[0012] Disperse calcium - aluminum hydrotalcite in deionized water to obtain a calcium - aluminum hydrotalcite dispersion. Add a sodium dodecylbenzenesulfonate solution to the calcium - aluminum hydrotalcite dispersion, perform ultrasonic dispersion treatment, then add an acrylamide solution, and react after adjusting the pH of the solution. After the reaction is completed, cool the reaction solution to room temperature, filter the reaction solution, wash the precipitate, and dry it to obtain the modified calcium - aluminum hydrotalcite material.

[0013] Calcium - aluminum hydrotalcite has excellent heat resistance and flame - retardant properties and has a layered structure. In order to improve its compatibility with the coating matrix, modification is required. However, the layer spacing of calcium - aluminum hydrotalcite is relatively small, making it difficult to modify the surface and interlayer with modification materials. To solve the above problems, according to the ion - exchange characteristics of calcium - aluminum hydrotalcite, the present invention first inserts sodium dodecylbenzenesulfonate between the layers of calcium - aluminum hydrotalcite through ion exchange to expand its layer spacing, and then exchanges acrylamide macromolecules into the interlayer, thereby preparing an organic - inorganic hybrid material. Due to the principle of similar - phase solubility between acrylamide in the interlayer of the organic - inorganic hybrid material and the coating matrix, it can be uniformly dispersed in the coating matrix.

[0014] Preferably, the concentrations of the calcium-aluminum hydrotalcite dispersion, sodium dodecylbenzenesulfonate solution, and acrylamide solution are 0.05-0.08 g / ml, 0.05-0.06 g / ml, and 0.02-0.05 g / ml respectively; the mass ratio of the calcium-aluminum hydrotalcite dispersion, sodium dodecylbenzenesulfonate solution, and acrylamide solution is 1:1:(0.5-1).

[0015] Preferably, the pH of the reaction is 3.5-4.5, the temperature is 80 °C, and the time is 3-5 h.

[0016] Preferably, the preparation method of the graft-modified graphene / boron nitride material comprises the following steps:

[0017] Add graphene and boron nitride into anhydrous ethanol, perform ultrasonic treatment, then filter. Without drying the precipitate, directly add it to a solution of 3-(trimethoxysilyl)propyl methacrylate for impregnation activation treatment, then filter. Without drying the washed precipitate, directly add it to a mixed solution of methacryloyloxyethyl sulfobetaine, photoinitiator, and N,N-methylenebisacrylamide. After stirring and dispersing evenly, carry out ultraviolet graft polymerization. Finally, filter the reaction solution, wash the precipitate, and dry it to obtain the graft-modified graphene / boron nitride composite material.

[0018] Both boron nitride nanosheets and graphene have high thermal stability and chemical stability, good mechanical properties and flexibility, and have a certain absorption and scattering effect on ultraviolet light. The nanosheet layer structures of both can destroy the cell walls and cell membranes of bacteria, thereby killing or inhibiting the growth of bacteria. Adding boron nitride nanosheets and graphene to the coating matrix can effectively improve the comprehensive performance of the coating.

[0019] In order to improve the compatibility of boron nitride nanosheets, graphene and the coating matrix, the present invention first performs a mixing and ultrasonic treatment on graphene and boron nitride, and uses the cavitation effect and shear force generated by the ultrasonic treatment to effectively break the agglomeration between the nanomaterials, thereby improving the dispersibility of graphene and boron nitride nanosheets; in order to avoid the formation of hard agglomerates of the dispersed nanomaterials, the precipitate is directly added to a solution of 3-(trimethoxysilyl)propyl methacrylate without drying for impregnation activation treatment. 3-(Trimethoxysilyl)propyl methacrylate can form chemical bonds with the functional groups on the surfaces of graphene and boron nitride, thereby further improving their dispersibility and compatibility with the coating matrix, and facilitating the next treatment of graphene and boron nitride nanosheets. In order to further improve the dispersibility of graphene and boron nitride nanosheets, the present invention also performs graft modification using methacryloyloxyethyl sulfobetaine as the graft monomer. The polymer chains generated by the polymerization reaction will wind or coat on the surfaces of graphene and boron nitride nanomaterials. On the one hand, it further improves their compatibility with the coating matrix; on the other hand, this polymer layer can bind to the bacterial cell membrane through electrostatic interaction, change the permeability of the cell membrane, and thus inhibit the growth of bacteria.

[0020] Preferably, the mass ratio of graphene to boron nitride is (2 - 5):1; the power of the ultrasonic treatment is 200 - 500 W, and the ultrasonic time is 1 - 3 h.

[0021] Preferably, the solution of 3-(trimethoxysilyl)propyl methacrylate is prepared by adding 3-(trimethoxysilyl)propyl methacrylate to a mixed solution of methanol and deionized water; the volume ratio of 3-(trimethoxysilyl)propyl methacrylate, methanol, and deionized water is 5:(90 - 95):(3 - 5).

[0022] Preferably, the temperature of the impregnation activation treatment is room temperature, the time is 20 - 30 h, and the mass ratio of the precipitate to 3-(trimethoxysilyl)propyl methacrylate is 1:(0.03 - 0.05).

[0023] Preferably, during the UV graft polymerization, the mass ratio of the precipitate to methacryloyloxyethyl sulfobetaine is 1:(0.01 - 0.05).

[0024] Preferably, the photoinitiator is 2-hydroxy-4′-(2-hydroxyethoxy)-2-methylpropiophenone. In the mixed solution, using deionized water as the solvent, the concentration of methacryloyloxyethyl sulfobetaine is 0.1 - 0.2 g / ml, and the mass ratio of methacryloyloxyethyl sulfobetaine, methylene bisacrylamide, and photoinitiator is 5:(0.02 - 0.03):(0.01 - 0.05).

[0025] Preferably, the conditions for ultraviolet graft polymerization are as follows: irradiation with a high-pressure mercury lamp with a power of 400 W and a wavelength of 365 nm for ultraviolet light, a radiation distance of 15 cm, and a time of 20 - 30 min.

[0026] Preferably, the preparation method of the functionalized carbon black includes the following steps:

[0027] Add phytic acid and glycerol to ethanol, carry out a first temperature-raising reaction, then add urea to the reaction system to carry out a second temperature-raising reaction. After the reaction is completed, cool to room temperature, add β-cyclodextrin and pretreated carbon black to the reaction system, carry out ultrasonic treatment, and finally filter the reaction solution, wash the precipitate and dry it to obtain functionalized carbon black.

[0028] Carbon black is a carbonaceous material with excellent properties. It has excellent ultraviolet resistance and can be added as a reinforcing filler to coatings to improve the properties of coatings. However, its compatibility with the coating matrix is poor, and directly adding it to the coating will reduce the properties of the coating. To solve the above technical problems, in the present invention, phytic acid and glycerol are first subjected to an esterification reaction under certain conditions, and then complexed with urea to obtain ammonium phytic acid glycerate, which is modified on the surface of pretreated carbon black. This can not only improve the compatibility between carbon black and the coating matrix, but also both the phosphorus-containing ammonium phytic acid glycerate and carbon black have a flame retardant effect, thereby improving the properties of the coating.

[0029] Preferably, the molar ratio of phytic acid, glycerol, and urea is (0.02 - 0.03):(0.09 - 0.1):(0.1 - 0.2).

[0030] Preferably, the mass ratio of β-cyclodextrin, pretreated carbon black, and phytic acid is 2:1:(0.5 - 1).

[0031] Preferably, the temperature of the first temperature-raising reaction is 130 °C and the time is 2 - 3 h; the temperature of the second temperature-raising reaction is 110 °C and the time is 2 - 3 h.

[0032] Preferably, the temperature of ultrasonic treatment is room temperature, the power is 200 - 500 W, and the time is 20 - 50 min.

[0033] In the second aspect, the present invention provides a preparation method of a waterborne coating modified with a multifunctional composite filler, including the following steps:

[0034] (1) Prepare an emulsifier solution, stir and mix the first monomer and the emulsifier solution evenly to obtain a first pre-emulsion; add the fluorinated second monomer to the emulsifier solution and stir evenly to obtain a second pre-emulsion;

[0035] (2) Add nano-titanium dioxide to the emulsifier solution, stir evenly to obtain a dispersion, add 1 / 3 of the first pre-emulsion to the dispersion, heat up to 80 ± 2 °C, add 1 / 3 of the initiator solution, react until blue light appears, add the remaining first pre-emulsion and initiator solution, continue to heat up to 87 ± 2 °C after dropping, and keep the reaction for 0.5 - 1 h;

[0036] (3) After the reaction, cool the reaction system to 80 ± 2 °C, add the second pre-emulsion and initiator solution to the reaction solution, heat up to 87 ± 2 °C after dropping, keep the reaction for 0.5 - 1 h, and cool the reaction solution to room temperature after the reaction to obtain a modified core-shell acrylic dispersion;

[0037] (4) According to the metering ratio, mix and disperse the above-mentioned modified core-shell acrylic dispersion, multi-functional composite filler, defoamer, wetting agent, thickener, film-forming aid, and deionized water evenly to obtain a water-based coating.

[0038] Preferably, the emulsifier solution is a sodium dodecyl sulfate solution with a concentration of 0.5 - 1 wt%.

[0039] Preferably, in step (1), the first monomer is a mixture of methyl methacrylate, butyl acrylate, and acrylic acid. When preparing the first pre-emulsion, the mass ratio of methyl methacrylate, butyl acrylate, acrylic acid, and sodium dodecyl sulfate is (8 - 15):(10 - 15):3:(0.3 - 0.5);

[0040] and / or the fluorine-containing second monomer is a mixture of methyl methacrylate, butyl acrylate, acrylic acid, glycidyl methacrylate, isooctyl acrylate, 2-hydroxyethyl methacrylate, and 2,2,2-trifluoroethyl acrylate. When preparing the second pre-emulsion, the mass ratio of methyl methacrylate, butyl acrylate, acrylic acid, glycidyl methacrylate, isooctyl acrylate, 2-hydroxyethyl methacrylate, 2,2,2-trifluoroethyl acrylate, and sodium dodecyl sulfate is (5 - 8):(10 - 12):(1 - 2):(2 - 4):(1 - 1.5):(2 - 4):(2 - 3):(0.3 - 0.5);

[0041] and / or during polymerization, the volume ratio of the emulsifier solution in the first pre-emulsion, the second pre-emulsion, and the dispersion is 3:3:10.

[0042] Preferably, in step (2), the mass ratio of nano-titanium dioxide to the emulsifier is 5:(1 - 1.5).

[0043] Preferably, the initiator solution is a potassium persulfate solution with a concentration of 1 wt%. In step (2), the mass ratio of the initiator solution to the emulsifier solution in the dispersion is 1:(4 - 5); in step (3), the addition amount of the initiator solution is 0.2 - 0.3 times the mass of the emulsifier solution in the dispersion.

[0044] Due to the adoption of the above technical solution, the present invention has at least the following beneficial effects:

[0045] 1. The present invention provides a waterborne coating modified with a multifunctional composite filler, which includes a modified core-shell acrylic dispersion, a multifunctional composite filler, an antifoaming agent, a wetting agent, a thickening agent, a film-forming aid, and deionized water; the core of the modified core-shell acrylic dispersion is nano-titanium dioxide, and the outer layer is sequentially coated with acrylic resin and fluorine-modified acrylic resin; a certain amount of nano-titanium oxide is added during the preparation of the emulsion in the present invention. Nano-titanium dioxide can not only absorb ultraviolet rays, but also reflect and scatter ultraviolet rays, and has good chemical stability, which can improve the chemical reagent resistance and anti-ultraviolet performance of the coating to a certain extent; moreover, the shell material fluorine-modified acrylic resin has excellent weather resistance and wear resistance; the special structure of the modified core-shell acrylic dispersion enables nano-titanium dioxide to be effectively coated in acrylic resin and fluorine-modified acrylic resin, thus avoiding the agglomeration phenomenon of nano-particles; the present invention also modifies the coating with a self-made multifunctional composite filler, and the prepared waterborne coating has good comprehensive performance.

[0046] 2. The multifunctional composite filler of the present invention includes a certain amount of modified calcium-aluminum hydrotalcite material, which is prepared by first inserting sodium dodecylbenzenesulfonate into the interlayer of the calcium-aluminum hydrotalcite material and then inserting acrylamide. The modified calcium-aluminum hydrotalcite material has good interfacial properties with the coating matrix. The calcium-aluminum hydrotalcite material has certain flame retardant properties. During the combustion process, interlayer water loss and dehydroxylation reactions will occur, releasing water and carbon dioxide. These gases can dilute and block combustible gases, and the residue after decomposition is a mixed metal oxide, which can effectively adsorb harmful gases and promote the formation of dense carbon slag, having a dual role of flame retardancy and smoke suppression, and can effectively improve the flame retardant performance of the coating. Moreover, the modified calcium-aluminum hydrotalcite material has a large specific surface area and excellent dispersibility, and can form a tight bond with the coating matrix, thereby improving the mechanical properties and impact resistance of the coating.

[0047] 3. The multifunctional composite filler of the present invention includes a certain amount of graft-modified graphene / boron nitride material. First, graphene and boron nitride are ultrasonically compounded and then silanized. Finally, it is graft-polymerized and modified with methacryloyloxyethyl sulfobetaine as the monomer, so as to form a polymer coating on the surface of the graphene / boron nitride material, improving the compatibility between the graphene / boron nitride material and the coating matrix. Graphene and boron nitride are two-dimensional layered materials with excellent properties. Graphene and boron nitride have good thermal stability and excellent barrier properties, and can increase the limiting oxygen index of the coating at high temperatures. The lamellar structure of graphene and boron nitride can also disperse the impact force well, enabling the coating to better absorb and disperse energy when being impacted, thereby improving the impact resistance of the coating, and can also significantly increase the tensile strength of the coating. In addition, graphene and boron nitride themselves have a certain absorption and scattering effect on ultraviolet light, and their nanosheet structure can destroy the cell walls and cell membranes of bacteria, thereby killing or inhibiting the growth of bacteria, and then improving the ultraviolet resistance and antibacterial properties of the coating.

[0048] 4. The multifunctional composite filler of the present invention includes a certain amount of functionalized carbon black. First, the carbon black is pretreated to introduce active groups on the surface of the carbon black, facilitating subsequent modification treatment of the carbon black. The modified materials β-cyclodextrin and ammonium glycerophosphate have multiple active groups such as hydroxyl groups and carboxyl groups, and these groups can react with the active groups on the surface of the carbon black to form strong chemical bonds. β-cyclodextrin can act as a dispersant, stabilizer or thickener, etc. in the coating, improving the dispersibility, stability and fluidity of the coating, while ammonium glycerophosphate can also interact with other components in the coating, thereby improving the adhesion, hardness and chemical resistance of the coating. In addition, the introduction of β-cyclodextrin and ammonium glycerophosphate can significantly improve the dispersibility and stability of carbon black in the coating, helping to reduce the agglomeration and precipitation of carbon black, making the coating more uniform and delicate.

[0049] 5. The present invention uses a modified calcium-aluminum hydrotalcite material, a graft-modified graphene / boron nitride material, and a functionalized carbon black compound as multifunctional fillers to modify coatings. The modified calcium-aluminum hydrotalcite material and the graft-modified graphene / boron nitride material have rich active groups on their surfaces. The interlayer structure of the modified calcium-aluminum hydrotalcite can provide a large surface area, providing a good basis for the dispersion and interaction of other materials. While the graft-modified graphene / boron nitride material provides high electrical conductivity and thermal conductivity, it can also interact with the surface of calcium-aluminum hydrotalcite, thereby improving the overall performance of the material; the modified calcium-aluminum hydrotalcite can improve the mechanical properties, corrosion resistance, and flame retardancy of the coating, while the graft-modified graphene helps to improve the electrical conductivity and thermal stability of the coating, and the functionalized carbon black can enhance the hiding power and wear resistance of the coating. The superposition of the above excellent effects can significantly improve the comprehensive performance of the coating; the modified calcium-aluminum hydrotalcite, graphene, and boron nitride can enhance the compatibility with the coating matrix through surface chemical modification. The improvement of the compatibility between the components helps for good adhesion between the materials, thereby improving the adhesion, wear resistance, and anti-aging ability of the coating. In summary, the good combination of the modified calcium-aluminum hydrotalcite, the graft-modified graphene / boron nitride, and the functionalized carbon black, working synergistically with each other, greatly improves the comprehensive performance of the waterborne coating. Detailed Embodiments

[0050] In order to more clearly understand the above-mentioned objects, features, and advantages of the present invention, the solution of the present invention will be further described below. It should be noted that, without conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other.

[0051] In the following description, many specific details are set forth in order to fully understand the present invention, but the present invention can also be implemented in other ways different from those described herein; obviously, the embodiments in the specification are only part of the embodiments of the present invention, rather than all of the embodiments.

[0052] To further understand the present invention, the preferred embodiments of the present invention will be described below in conjunction with embodiments. However, it should be understood that these descriptions are only for further explaining the features and advantages of the present invention, rather than limiting the claims of the present invention.

[0053] In the following examples and comparative examples, the performance parameters and sources of some raw materials are as follows:

[0054] The defoamer is BYK-028, the wetting agent is BYK-346, the film-forming aid is alcohol ester-12, and the thickener is Rheovis RM-12W;

[0055] Calcium-aluminum hydrotalcite: Hubei Dongcao Chemical Technology Co., Ltd.;

[0056] Graphene: Carboxylated graphene oxide powder purchased from Jiangsu Xianfeng Nano Materials Technology Co., Ltd., sheet diameter: 0.5 - 5 microns, thickness: 0.8 - 1.2 nanometers;

[0057] Boron nitride: Hydroxylated boron nitride nanosheets purchased from Jiangsu Xianfeng Nano Materials Technology Co., Ltd.;

[0058] Nano titanium dioxide: TiO2 anatase nano titanium dioxide, average particle size is 30 - 40 nm, purchased from Jiangsu Xianfeng Nano Materials Technology Co., Ltd.;

[0059] Carbon black: Environmentally friendly carbon black N550, Qingzhou Boao Carbon Black Co., Ltd.;

[0060] The process of carbon black pretreatment is as follows: Disperse 2 g of carbon black and 20 ml of nitric acid solution with a concentration of 60 wt% under ultrasonic dispersion at 300 W for 30 min, heat up to 100 °C under an inert atmosphere and treat for 24 h, filter after the treatment, wash the precipitate until neutral and then dry to obtain pretreated carbon black.

[0061] Unless otherwise specified, all raw materials of the present invention are commercially available or raw materials that can be obtained by those skilled in the art. Unless otherwise specified, all methods in the embodiments of the present invention are methods mastered by those skilled in the art. Example 1

[0062] A preparation method of a multifunctional composite filler, comprising the following steps:

[0063] S1: Disperse 7 g of calcium aluminate hydrotalcite in 100 ml of deionized water to obtain a calcium aluminate hydrotalcite dispersion liquid. Add a sodium dodecylbenzenesulfonate solution prepared by mixing 5 g of sodium dodecylbenzenesulfonate with 100 ml of deionized water to the calcium aluminate hydrotalcite dispersion liquid, perform ultrasonic dispersion treatment at 500 W for 10 min, then add an acrylamide solution prepared by mixing 60 ml of deionized water with 3 g of acrylamide, adjust the pH of the solution to 4, heat up to 80 °C and react for 4 h. After the reaction is completed, cool the reaction solution to room temperature, filter the reaction solution, wash the precipitate and then dry to obtain a modified calcium aluminate hydrotalcite material;

[0064] S2: Add 3 g of graphene and 1 g of boron nitride into 50 ml of absolute ethanol, and perform ultrasonic treatment at 500 W for 3 h. Then filter, and directly add the precipitate without drying into the solution of 3-(trimethoxysilyl)propyl methacrylate (the solution composed of 3-(trimethoxysilyl)propyl methacrylate, methanol, and deionized water in a volume ratio of 5:95:4), and perform impregnation activation treatment at room temperature for 24 h. The mass ratio of the precipitate to 3-(trimethoxysilyl)propyl methacrylate during the impregnation activation treatment is 1:0.03. After the impregnation activation treatment, filter, wash the precipitate, and directly add it without drying into the mixed solution of methacryloyloxyethyl sulfobetaine, 2-hydroxy-4′-(2-hydroxyethoxy)-2-methylpropiophenone, and N,N-methylenebisacrylamide (in the mixed solution, the mass ratio of methacryloyloxyethyl sulfobetaine, methylenebisacrylamide, 2-hydroxy-4′-(2-hydroxyethoxy)-2-methylpropiophenone, and deionized water is 5:0.02:0.02:45). Control the mass ratio of the precipitate to methacryloyloxyethyl sulfobetaine to be 1:0.04. After stirring and dispersing at a rotation speed of 1000 rpm for 30 min, irradiate the reaction solution with a high-pressure mercury lamp with a power of 400 W and an ultraviolet wavelength of 365 nm, control the surface distance between the high-pressure mercury lamp and the reaction solution to be 15 cm, and the time to be 30 min. After the reaction, filter the reaction solution, wash the precipitate, and dry it to obtain the graft-modified graphene / boron nitride composite material;

[0065] S3: Add 0.025 mol of phytic acid and 0.09 mol of glycerol into 50 ml of ethanol, heat up to 130 °C, and react for 3 h. Cool the reaction solution to 110 °C, then add 0.11 mol of urea into the reaction system, keep the temperature for reaction for 2 h. After the reaction, cool to room temperature, add β-cyclodextrin and pretreated carbon black into the reaction system (control the mass ratio of β-cyclodextrin, pretreated carbon black, and phytic acid to be 2:1:0.5), perform ultrasonic treatment at 500 W for 30 min, and finally filter the reaction solution, wash the precipitate, and dry it to obtain the functionalized carbon black;

[0066] S4: Mix and grind the mixture of the above modified calcium aluminate hydrotalcite material, graft-modified graphene / boron nitride material, and functionalized carbon black in a mass ratio of 3:4:15 to obtain the multifunctional composite filler. Example 2

[0067] Compared with Example 1, the difference is that in S4, the ratio of the mixture of the modified calcium aluminate hydrotalcite material, graft-modified graphene / boron nitride material, and functionalized carbon black is 3:5:20, and other conditions are the same as those in Example 1.

[0068] Comparative Example 1

[0069] Compared with Example 1, the difference is that the filler only includes the modified calcium aluminum hydrotalcite material, and other conditions are the same as those in Example 1.

[0070] Comparative Example 2

[0071] Compared with Example 1, the difference is that the filler only includes grafted modified graphene / boron nitride material, and other conditions are the same as those in Example 1.

[0072] Comparative Example 3

[0073] Compared with Example 1, the difference is that the filler only includes functionalized carbon black, and other conditions are the same as those in Example 1.

[0074] Comparative Example 4

[0075] Compared with Example 1, the difference is that the filler does not include modified calcium aluminum hydrotalcite material, and other conditions are the same as those in Example 1.

[0076] Comparative Example 5

[0077] Compared with Example 1, the difference is that the filler does not include the grafted modified graphene / boron nitride material, and other conditions are the same as those in Example 1.

[0078] Comparative Example 6

[0079] Compared with Example 1, the difference is that the filler does not include functionalized carbon black, and other conditions are the same as those in Example 1. Example 3

[0080] A method for preparing a water-based coating modified with a multifunctional composite filler comprises the following steps:

[0081] (1) 0.5 g of sodium dodecyl sulfate and 100 ml of deionized water were mixed and stirred to obtain a sodium dodecyl sulfate solution, and methyl methacrylate, butyl acrylate, acrylic acid and sodium dodecyl sulfate solution were mixed and stirred evenly (the mass ratio of methyl methacrylate, butyl acrylate, acrylic acid and sodium dodecyl sulfate was controlled to be 8:10:3:0.4), and the mixture was stirred evenly to obtain a first pre-emulsion; methyl methacrylate, butyl acrylate, acrylic acid, glycidyl methacrylate, isooctyl acrylate, hydroxyethyl methacrylate, trifluoroethyl acrylate and sodium dodecyl sulfate solution were mixed and stirred evenly (the mass ratio of methyl methacrylate, butyl acrylate, acrylic acid, glycidyl methacrylate, isooctyl acrylate, hydroxyethyl methacrylate, trifluoroethyl acrylate and sodium dodecyl sulfate was controlled to be 7.5:10:1.2:3:1.2:3:3:0.35), and the second pre-emulsion was obtained;

[0082] (2) Add nano-titanium dioxide (the mass ratio of nano-titanium dioxide to sodium dodecyl sulfate is 5:1) to 50 ml of a 0.5 wt% sodium dodecyl sulfate solution. After stirring evenly, add 5 ml of the first pre-emulsion, heat up to 80 °C, add 3.3 g of a 1 wt% potassium persulfate solution, react until blue light appears, add 10 ml of the first pre-emulsion and 6.7 g of potassium persulfate solution, continue to heat up to 87 °C after the dropping is completed, and keep the reaction at this temperature for 1 h;

[0083] (3) After the reaction is completed, cool the reaction system to 80 °C, add 15 ml of the second pre-emulsion and 11 g of a 1 wt% potassium persulfate solution to the reaction solution, heat up to 87 °C after the dropping is completed, keep the reaction at this temperature for 1 h, and cool the reaction solution to room temperature after the reaction is completed to obtain a modified core-shell acrylic dispersion;

[0084] (4) According to the metering ratio, mix and disperse evenly 85 parts of the above-mentioned modified core-shell acrylic dispersion, 5 parts of the multifunctional composite filler prepared in Example 1, 0.5 part of defoamer, 0.5 part of wetting agent, 4 parts of thickener, 2 parts of film-forming aid, and 30 parts of deionized water to obtain a water-based coating. Example 4

[0085] [[ID=]11] Compared with Example 3, the difference is that the multifunctional composite filler of Example 2 in equal amount is used to replace the multifunctional composite filler prepared in Example 1, and other conditions are the same as those in Example 3. Example 5

[0086] Compared with Example 3, the difference is that the addition amount of the multifunctional composite filler is 6 parts, and other conditions are the same as those in Example 3.

[0087] Comparative Example 7

[0088] Compared with Example 3, the difference is that the filler of Comparative Example 1 in equal amount is used to replace the multifunctional composite filler prepared in Example 1, and other conditions are the same as those in Example 3.

[0089] Comparative Example 8

[0090] Compared with Example 3, the difference is that the filler of Comparative Example 2 in equal amount is used to replace the multifunctional composite filler prepared in Example 1, and other conditions are the same as those in Example 3.

[0091] Comparative Example 9

[0092] Compared with Example 3, the difference is that the filler of Comparative Example 3 in equal amount is used to replace the multifunctional composite filler prepared in Example 1, and other conditions are the same as those in Example 3.

[0093] Comparative Example 10

[0094] Compared with Example 3, the difference lies in that: an equal amount of the filler of Comparative Example 4 is used to replace the multifunctional composite filler prepared in Example 1, and other conditions are the same as those in Example 3.

[0095] Comparative Example 11

[0096] Compared with Example 3, the difference lies in that: an equal amount of the filler of Comparative Example 5 is used to replace the multifunctional composite filler prepared in Example 1, and other conditions are the same as those in Example 3.

[0097] Comparative Example 12

[0098] Compared with Example 3, the difference lies in that: an equal amount of the filler of Comparative Example 6 is used to replace the multifunctional composite filler prepared in Example 1, and other conditions are the same as those in Example 3.

[0099] Comparative Example 13

[0100] Compared with Example 3, the difference lies in that: no multifunctional composite filler is added, and other conditions are the same as those in Example 3.

[0101] Comparative Example 14

[0102] Compared with Example 3, the difference lies in that: in step (2), nano-titanium dioxide is not added, and other conditions are the same as those in Example 3.

[0103] Comparative Example 15

[0104] Compared with Example 3, the difference lies in that: in step (2), nano-titanium dioxide is not added, and in step (4), no multifunctional composite filler is added, and other conditions are the same as those in Example 3.

[0105] The performance tests of the waterborne coatings of the above Examples 3-5 and Comparative Examples 7-15 were carried out, and the test methods and test results are as follows.

[0106] 1. Storage stability test:

[0107] The coatings of the above Examples 3-5 and Comparative Examples 7-15 were stored at room temperature for 7 days, and the dispersion of the coatings was observed.

[0108] 2. Antibacterial performance test:

[0109] The test was carried out in accordance with the standard of HG / T3950-2007. The data after 56 days of using Staphylococcus aureus and Escherichia coli were used, and the measured values were the average of 10 tests.

[0110] The coatings of the above Examples 3-5 and Comparative Examples 7-15 were respectively sprayed on steel plates and cured for 5 days to obtain a coating with a thickness of 80 μm. The performance tests of the coatings were carried out:

[0111] 3. Adhesion test:

[0112] It is carried out according to the standard of GB / T9286-1998, and the cross-cut method is used for testing. A grid with a spacing of 1 mm is drawn on the coating surface, and after peeling off with tape, the peeling situation is observed. The rating standard is from 0 to 5 levels, where level 0 indicates no peeling, and level 5 indicates that the peeling area exceeds 65%.

[0113] 4. Chemical resistance test:

[0114] The cured coating is placed in the medium, and the medium includes water, acid (HCl with a mass fraction of 10%), and alkali (NaOH with a mass fraction of 10%). After 200 h, it is taken out, blotted dry with filter paper, and the foaming and rusting phenomena are observed.

[0115] 5. Impact resistance test:

[0116] The test is carried out according to GB / T1732-1993 "Determination of Film Impact Resistance", and different heights are selected by the impact tester for the impact test. Three points are selected for the impact test on each sample board, and if one point fails, it is considered a failure. Select an appropriate impact height and conduct the test again to finally obtain the result.

[0117] 6. Wear resistance test:

[0118] According to the test method specified in GB 1768-2006 "Paints and Varnishes - Determination of Abrasion Resistance - Rotating Rubber Wheel Method", the mass loss of the test sample is tested, and the test conditions are CS-17 grinding wheel, 1000 g / 1000 r.

[0119] 7. UV aging performance test:

[0120] The coatings of the above-mentioned examples and comparative examples are prepared into a coating film with a thickness of 2 mm, and the coating film is cut into specimens of 100 mm×50 mm, placed under a 30W UV lamp, 5 cm away from the light source, irradiated for 240 h, and the tensile properties of the specimens before and after irradiation are tested. The tensile property test is carried out by a universal tensile machine, and the tensile speed is 2 mm / min.

[0121] 8. Limiting oxygen index test:

[0122] The limiting oxygen index of the polypropylene composite material with a flame-retardant coating is detected by a ZR-01 intelligent oxygen index measuring instrument, according to GB / T38301-2019.

[0123] The test results are shown in Table 1 and Table 2.

[0124] Table 1

[0125]

[0126] Table 2

[0127]

[0128] The test results of Table 1 and Table 2 are analyzed as follows:

[0129] Compared with the comparative examples, the waterborne coatings prepared in Examples 3-5 of the present invention are modified by adding a multifunctional composite filler composed of a modified calcium-aluminum hydrotalcite material, a graft-modified graphene / boron nitride material, and a functionalized carbon black. The comprehensive properties of the coatings, such as adhesion, antibacterial property, chemical reagent resistance, abrasion resistance, impact resistance, tensile property, and flame retardancy, have been improved to a certain extent, and the coating stability is good.

[0130] Compared with other comparative examples, the waterborne coating of Comparative Example 15 does not add a multifunctional composite filler, and nano-titanium oxide is not added during the preparation of the modified core-shell acrylic dispersion, so the performance of the coating is the worst.

[0131] Compared with the examples, in Comparative Examples 7-12, the fillers in the waterborne coatings are single components or a combination of two components, and the comprehensive performance of the coatings is inferior to that of the examples. This shows that the three components in the functional composite filler of the present invention have a certain synergistic effect.

[0132] Specific examples are used in this article to elaborate on the principles and implementation manners of the present invention. The description of the above examples is only used to help understand the method and its core idea of the present invention, including the best mode, and also enables any person skilled in the art to practice the present invention, including manufacturing and using any device or system, and implementing any combined method. It should be noted that for those of ordinary skill in the art in this technical field, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention. The protection scope of the present invention patent is defined by the claims and may include other embodiments that can be conceived by those skilled in the art. If these other embodiments have structural elements similar to the literal description of the claims, or if they include equivalent structural elements that have no substantial difference from the literal description of the claims, then these other embodiments should also be included within the scope of the claims.

Claims

1. A water-based coating modified with a multifunctional composite filler, characterized in that: By weight, it includes 80 - 100 parts of modified core - shell acrylic dispersion, 5 - 7 parts of multi - functional composite filler, 0.5 - 1 part of defoamer, 0.5 - 1 part of wetting agent, 2 - 5 parts of thickener, 1 - 2 parts of film - forming auxiliary, and 25 - 35 parts of deionized water; the multi - functional composite filler is a mixture of modified calcium - aluminum hydrotalcite material, graft - modified graphene / boron nitride material, and functionalized carbon black, and the mass ratio of the modified calcium - aluminum hydrotalcite material, graft - modified graphene / boron nitride material, and functionalized carbon black is (2 - 5):(3 - 8):(10 - 20); the core of the modified core - shell acrylic dispersion is nano - titanium dioxide, and the outer layer is coated with acrylic resin and fluorine - modified acrylic resin in sequence. The modified calcium - aluminum hydrotalcite material is prepared by first inserting sodium dodecylbenzenesulfonate between the layers of calcium - aluminum hydrotalcite material and then inserting acrylamide; specifically, it includes the following steps: dispersing calcium - aluminum hydrotalcite in deionized water to obtain a calcium - aluminum hydrotalcite dispersion, adding a sodium dodecylbenzenesulfonate solution to the calcium - aluminum hydrotalcite dispersion, performing ultrasonic dispersion treatment and then adding an acrylamide solution, reacting after adjusting the pH of the solution, cooling the reaction solution to room temperature after the reaction, filtering the reaction solution, washing the filtered precipitate and then drying to obtain the modified calcium - aluminum hydrotalcite material. The preparation method of the graft - modified graphene / boron nitride material includes the following steps: Adding graphene and boron nitride in a mass ratio of (2 - 5):1 to absolute ethanol, performing ultrasonic treatment at 200 - 500W for 1 - 3h, then filtering, adding the precipitate directly without drying to a solution of 3 - (trimethoxysilyl)propyl methacrylate for impregnation activation treatment, then filtering, adding the precipitate directly without drying to a mixed solution of methacryloyloxyethyl sulfobetaine, photo - initiator, and N,N - methylenebisacrylamide, stirring and dispersing evenly, performing ultraviolet graft polymerization, and finally filtering the reaction solution, washing the precipitate and then drying to obtain the graft - modified graphene / boron nitride composite material. The functionalized carbon black is prepared by pretreating carbon black and then modifying it with β - cyclodextrin and ammonium glycerophosphate respectively. The ammonium glycerophosphate is prepared by the esterification reaction of glycerol and phytic acid and the complexation reaction with urea; the molar ratio of phytic acid, glycerol, and urea is (0.02 - 0.03):(0.09 - 0.1):(0.1 - 0.2); the mass ratio of β - cyclodextrin, pretreated carbon black, and phytic acid is 2:1:(0.5 - 1).

2. The waterborne coating modified with a multifunctional composite filler according to claim 1, characterized in that: The concentrations of the calcium - aluminum hydrotalcite dispersion, sodium dodecylbenzenesulfonate solution, and acrylamide solution are 0.05 - 0.08g / ml, 0.05 - 0.06g / ml, and 0.02 - 0.05g / ml respectively; the mass ratio of the calcium - aluminum hydrotalcite dispersion, sodium dodecylbenzenesulfonate solution, and acrylamide solution is ​ 3. The waterborne coating modified with a multifunctional composite filler according to claim 1, characterized in that: ​ a: The 3-(trimethoxysilyl)propyl methacrylate solution is prepared by adding 3-(trimethoxysilyl)propyl methacrylate into a mixed solution of methanol and deionized water; the volume ratio of 3-(trimethoxysilyl)propyl methacrylate, methanol, and deionized water is 5:(90 - 95):(3 - 5); b: The temperature for impregnation activation treatment is room temperature, the time is 20 - 30 h, and the mass ratio of the precipitate to 3-(trimethoxysilyl)propyl methacrylate is 1:(0.03 - 0.05); c: During ultraviolet graft polymerization, the photoinitiator is 2-hydroxy-4′-(2-hydroxyethoxy)-2-methylpropiophenone; the mass ratio of the precipitate to methacryloyloxyethyl sulfobetaine is 1:(0.01 - 0.05); d: In the mixed solution, using deionized water as the solvent, the concentration of methacryloyloxyethyl sulfobetaine is 0.1 - 0.2 g / ml, and the mass ratio of methacryloyloxyethyl sulfobetaine, N,N-methylenebisacrylamide, and photoinitiator is 5:(0.02 - 0.03):(0.01 - 0.05); e: The conditions for ultraviolet graft polymerization are: irradiation with a high-pressure mercury lamp with a power of 400 W and an ultraviolet light wavelength of 365 nm, a radiation distance of 15 cm, and a time of 20 - 30 min.

4. The waterborne coating modified with a multifunctional composite filler according to claim 1, characterized in that: The preparation method of the functionalized carbon black includes the following steps: Add phytic acid and glycerol into ethanol, conduct a first temperature-raising reaction, then add urea to the reaction system for a second temperature-raising reaction. After the reaction ends, cool to room temperature, add β-cyclodextrin and pretreated carbon black to the reaction system, conduct ultrasonic treatment, and finally filter the reaction solution, wash the precipitate and dry it to obtain functionalized carbon black.

5. The waterborne coating modified with a multifunctional composite filler according to claim 4, wherein: The temperature of the first temperature-raising reaction is 130 °C and the time is 2 - 3 h; the temperature of the second temperature-raising reaction is 110 °C and the time is 2 - 3 h; the temperature for ultrasonic treatment is room temperature, the power is 200 - 500 W, and the time is 20 - 50 min.

6. The preparation method of a water-based coating modified by a multifunctional composite filler according to any one of claims 1-5, characterized in that, It includes the following steps: (1) Prepare an emulsifier solution, stir and mix the first monomer and the emulsifier solution evenly to obtain a first pre-emulsion; Add the fluorinated second monomer to the emulsifier solution and stir evenly to obtain a second pre-emulsion; (2) Add nano-titanium dioxide to the emulsifier solution, stir evenly to obtain a dispersion, add 1 / 3 of the first pre-emulsion to the dispersion, raise the temperature to 80 ± 2 °C, add 1 / 3 of the initiator solution, react until blue light appears, add the remaining first pre-emulsion and initiator solution, continue to raise the temperature to 87 ± 2 °C after the addition is completed, and keep the temperature for reaction for 0.5 - 1 h; (3) After the reaction ends, cool the reaction system to 80 ± 2 °C, add the second pre-emulsion and initiator solution to the reaction solution, raise the temperature to 87 ± 2 °C after the addition is completed, keep the temperature for reaction for 0.5 - 1 h, and cool the reaction solution to room temperature after the reaction ends to obtain a modified core-shell acrylic dispersion; (4) According to the metering ratio, mix and disperse the above-mentioned modified core-shell acrylic dispersion, multi-functional composite filler, defoamer, wetting agent, thickener, film-forming aid, and deionized water evenly to obtain a water-based coating.

7. The preparation method of an aqueous coating modified with a multifunctional composite filler according to claim 6, characterized in that: In step (1), the first monomer is a mixture of methyl methacrylate, butyl acrylate, and acrylic acid. When preparing the first pre-emulsion, the mass ratio of methyl methacrylate, butyl acrylate, acrylic acid, and emulsifier is (8 - 15):(10 - 15):3:(0.3 - 0.5); and / or the fluorine-containing second monomer is a mixture of methyl methacrylate, butyl acrylate, acrylic acid, glycidyl methacrylate, isooctyl acrylate, 2-hydroxyethyl methacrylate, and 2,2,2-trifluoroethyl acrylate. When preparing the second pre-emulsion, the mass ratio of methyl methacrylate, butyl acrylate, acrylic acid, glycidyl methacrylate, isooctyl acrylate, 2-hydroxyethyl methacrylate, 2,2,2-trifluoroethyl acrylate, and emulsifier is (5 - 8):(10 - 12):(1 - 2):(2 - 4):(1 - 1.5):(2 - 4):(2 - 3):(0.3 - 0.5); and / or during polymerization, the volume ratio of the emulsifier solution in the first pre-emulsion, the second pre-emulsion, and the dispersion liquid is 3:3:

10.

8. The preparation method of a waterborne coating modified with a multifunctional composite filler according to claim 6, characterized in that: The emulsifier solution is a sodium dodecyl sulfate solution with a concentration of 0.5 - 1 wt%; the initiator solution is a potassium persulfate solution with a concentration of 1 wt%; In step (2), the mass ratio of nano-titanium dioxide to the emulsifier is 5:(1 - 1.5); In step (2), the mass ratio of the initiator solution to the emulsifier solution in the dispersion liquid is 1:(4 - 5); In step (3), the addition amount of the initiator solution is 0.2 - 0.3 times the mass of the emulsifier solution in the dispersion liquid.

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