A high-whiteness sericite water-based paint and preparation method thereof

Abstract

The present invention belongs to the technical field of coatings, and specifically relates to a high-whiteness sericite water-based coating and a preparation method thereof. The present invention aims to solve the problem of insufficient functionality of existing high-whiteness sericite coatings. The present invention crushes and grinds sericite ore to obtain sericite ore powder, and sequentially performs flotation purification and magnetic separation purification to obtain refined ore powder; the refined ore powder is subjected to sequential chemical bleaching and simultaneous surface deposition and grafting modification to obtain high-whiteness sericite powder; the high-whiteness sericite powder is mixed with a water-based acrylic emulsion and an auxiliary agent, and subjected to vacuum degassing and aging treatment to obtain a high-whiteness sericite water-based coating. The high-whiteness sericite water-based coating prepared by the present invention has high whiteness and high color uniformity, as well as excellent wear resistance, and has certain antibacterial and hydrophobic properties, making it suitable as an indoor coating.

Description

Technical Field

[0001] The invention belongs to the technical field of coatings, and particularly relates to a high-whiteness sericite water-based coating and a preparation method thereof. Background Art

[0002] Sericite, a natural mineral, has a long history of application. In modern times, it has been widely used as a coating filler with excellent properties in architectural coatings, anti-corrosion coatings, road marking coatings, marine coatings, and other fields.

[0003] In recent years, water-based coatings using sericite as a filler have attracted increasing attention from the industry as a new type of coating that combines environmental friendliness and functionality. High-whiteness sericite powder can significantly improve the whiteness and brightness of coatings. Its flaky structure imparts a superior gloss, while also providing excellent weather resistance and a low risk of pollutants.

[0004] With increasing demand for environmentally friendly coatings, the market demand for high-quality, functionalized, and environmentally friendly water-based sericite coatings continues to grow. While existing sericite coatings offer many excellent properties, their high whiteness and other functionalities are often difficult to achieve simultaneously. High-whiteness treated sericite is generally difficult to modify, hindering its ability to achieve a wider range of functionalities. Simply adding other brighteners to the coating increases process complexity and negatively impacts the gloss and environmental performance of the existing sericite coating.

[0005] At present, the insufficient functionality of existing high-whiteness sericite coatings remains a major problem facing the industry.

[0006] Therefore, a high-whiteness sericite water-based coating and a preparation method thereof are proposed. Summary of the Invention

[0007] The present invention aims to provide a high-whiteness sericite water-based coating and a preparation method thereof. The method comprises crushing and grinding sericite ore to obtain sericite ore powder, which is then subjected to flotation purification and magnetic separation to obtain refined ore powder. The refined ore powder is subjected to sequential chemical bleaching and simultaneous surface deposition and grafting modification to obtain high-whiteness sericite powder. The high-whiteness sericite powder is then mixed with a water-based acrylic emulsion and an additive, and subjected to vacuum degassing and aging treatment to produce the high-whiteness sericite water-based coating.

[0008] To achieve the above object, the present invention provides the following technical solutions:

[0009] A method for preparing a high-whiteness sericite water-based coating comprises the following steps:

[0010] Unless otherwise specified, the parts in the present invention refer to parts by mass.

[0011] The sericite ore is crushed and ground by a crushing device and a grinding device, and the ore powder with a size less than 400 mesh is selected by screening to obtain sericite ore powder.

[0012] Sericite ore powder is mixed with deionized water to prepare a pulp at a pulp concentration of 25%, and the pH is adjusted to 8-9 to obtain a sericite ore pulp. To 1000 parts of the sericite ore pulp, 0.1 parts of sodium oleate, 0.2 parts of sodium silicate, and 0.05 parts of methyl isobutyl carbinol are added. After flotation for 10 minutes, the froth layer is collected to enrich the ore powder, which is then mixed with deionized water again to prepare a pulp concentration of 10%-20%. After adding 0.08 wt‰ of sodium silicate, the sericite ore pulp is flotated for 5 minutes, and the froth layer is collected to obtain a flotation pulp.

[0013] The flotation pulp concentration is adjusted to 25%-30%, and magnetic separation is carried out at a magnetic induction intensity of 1.2 T. The product is concentrated, filtered and dried to obtain refined ore powder.

[0014] The refined ore powder is subjected to sequential chemical bleaching to obtain bleached ore powder.

[0015] The surface of bleached mineral powder is modified to obtain high-whiteness sericite powder.

[0016] High-whiteness sericite powder is dispersed and mixed with a dispersant, deionized water and a wetting agent to obtain a filler slurry.

[0017] After the filler slurry is mixed with the water-based acrylic emulsion, a defoaming agent and a film-forming aid are added and mixed to prepare a slurry, and a coating precursor is obtained after vacuum degassing.

[0018] The coating precursor is subjected to a aging treatment to obtain a high-whiteness sericite water-based coating.

[0019] Preferably, the sequential chemical bleaching process includes: reductive bleaching and ultrasonic-assisted oxidative bleaching; wherein the reductive bleaching process is as follows: 200 parts of refined mineral powder are slowly added to 1000 parts of a 10% sodium sulfite aqueous solution, stirred at 300-500 rpm at 25°C for 20 minutes, adjusted to a pH of 3-5 and heated to 60°C, stirred at 100 rpm for 60 minutes, cooled to 25°C, filtered to obtain a solid product, washed with water, and dried to obtain pre-bleached mineral powder; the ultrasonic-assisted oxidative bleaching process is as follows: 200 parts of pre-bleached mineral powder are added to 1000 parts of a 5% hydrogen peroxide aqueous solution, adjusted to a pH of 9-10, treated at 70°C with an ultrasonic power of 250-300 W and an ultrasonic frequency of 30-40 kHz for 90 minutes, cooled to 25°C, filtered, washed with water, and dried to obtain bleached mineral powder.

[0020] Preferably, the surface modification process includes surface deposition and grafting modification, and the surface deposition and grafting modification are performed simultaneously.

[0021] Preferably, the specific process of surface modification is as follows: 10 parts of bleached mineral powder are added to 75 parts of deionized water, and treated at 60°C with an ultrasonic power of 220W and an ultrasonic frequency of 25kHz for 20 minutes, and then cooled to 50°C and continuously stirred at a speed of 500rpm. Under nitrogen protection, tetrabutyl titanate ethanol solution is added dropwise at a rate of 1.5 parts / min, and γ-aminopropyltriethoxysilane ethanol solution is added dropwise at a rate of 1.2 parts / min. After 70 minutes, the addition is stopped, and after cooling to 45°C, stirring is maintained at 500rpm for 3 hours to obtain a modified slurry; the modified slurry is added to a hydrothermal kettle, reacted at 140°C under the autogenous pressure of the hydrothermal kettle for 10 hours, and washed and dried to obtain high-whiteness sericite powder.

[0022] Preferably, the preparation process of the tetrabutyl titanate ethanol solution is: slowly adding 5 parts of tetrabutyl titanate to 50 parts of anhydrous ethanol, stirring at 200 rpm at 25°C for 30 minutes to obtain the tetrabutyl titanate ethanol solution; the preparation process of the γ-aminopropyl triethoxysilane ethanol solution is: slowly adding 1 part of γ-aminopropyl triethoxysilane to 20 parts of anhydrous ethanol, stirring at 150 rpm at 25°C for 15 minutes to obtain the γ-aminopropyl triethoxysilane ethanol solution.

[0023] Preferably, the dispersant includes sodium polyacrylate and sodium polyoxyethylene fatty alcohol ether sulfate, and the wetting agent is acetylene glycol polyether; the dispersion and mixing process is: 100 parts of high-whiteness sericite powder, 100 parts of deionized water, and 0.5 parts of acetylene glycol polyether are mixed, and stirred at a speed of 100 rpm at 25°C, and then 0.2 parts of sodium polyacrylate and 0.5 parts of sodium polyoxyethylene fatty alcohol ether sulfate are added, and the stirring speed is adjusted to 200 rpm and stirred for 20 minutes, and then treated at 40°C with an ultrasonic power of 250 W and an ultrasonic frequency of 20-30 kHz for 30 minutes to obtain a filler slurry.

[0024] Preferably, the aqueous acrylic emulsion is polybutyl acrylate, the defoaming agent is polydimethylsiloxane, and the film-forming aids include dipropylene glycol benzoate and isooctyl benzoate; the mixing and slurrying process is: 100 parts of filler slurry and 110-130 parts of polybutyl acrylate are stirred and mixed at 25°C and 500 rpm for 20 minutes, 0.5 parts of polydimethylsiloxane, 1 part of dipropylene glycol benzoate and 0.8 parts of isooctyl benzoate are added, and then the temperature is raised to 50°C, the stirring speed is reduced to 150-200 rpm, and the mixture is mixed for 30 minutes, and then cooled to 25°C to obtain a premixed coating.

[0025] Preferably, the vacuum degassing process is: under an operating pressure of 10 kPa, the premixed coating is degassed at a rotation speed of 200-250 rpm for 30 minutes to obtain a coating precursor.

[0026] Preferably, the aging process is as follows: shaking the coating precursor at 35° C. at a rate of 10 times / min, heating to 40° C. for 10 hours, and then standing for 48 hours to obtain a high-whiteness sericite water-based coating.

[0027] A high-whiteness sericite water-based paint comprises high-whiteness sericite powder, a dispersant, a wetting agent, a water-based acrylic emulsion, a defoaming agent and a film-forming aid.

[0028] The high-whiteness sericite water-based paint prepared by the present invention has the following basic parameters: whiteness WI ≥ 92.0 (Ganz whiteness formula, the same below); color uniformity ΔE ≤ 0.50; viscosity 820-1020 mPa·s; density 1.18-1.24 g / mL; 60° glossiness 15-20 GU; and visible light reflectivity ≥ 87%.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] 1. The crushed and ground sericite ore powder is sequentially subjected to flotation purification and magnetic separation. This effectively removes gangue minerals such as quartz and feldspar from the sericite ore while also efficiently separating magnetic minerals such as hematite and magnetite. This sequential flotation and magnetic separation ensures the graded removal of impurities and reduces the negative impact of non-ferrous and magnetic impurities on the whiteness of the sericite powder.

[0031] 2. A sequential chemical bleaching process is used to sequentially bleach the magnetically separated refined ore powder through reductive bleaching and ultrasonically assisted oxidative bleaching. This process removes some weakly coloring impurities, such as iron oxide, before further removing residual organic matter and strong coloring impurities. Ultrasound-assisted bleaching is then used to enhance the bleaching effect, improving bleaching efficiency and uniformity, significantly enhancing the whiteness and color uniformity of the finished paint. Furthermore, the effective removal of impurities ensures the environmental friendliness of the paint product, generating virtually no organic pollutants during use, making it suitable for interior paint.

[0032] 3. The bleached mineral powder after sequential chemical bleaching is subjected to simultaneous surface deposition and grafting modification. Through process synergy and complementary material properties, titanium dioxide whitening agent deposition and surface silane grafting modification are simultaneously completed on the mineral powder surface, enhancing the bonding strength between the deposited layer and the sericite substrate. The growth process and microstructure of the deposited layer are regulated in situ, significantly improving the density and uniformity of the deposited layer. Simultaneously, the simultaneous execution of these two processes forms an organic-inorganic composite structure in the deposited layer, endowing the sericite filler with excellent compatibility with the coating matrix. This expands the coating's range of functionalities, enabling the sericite coating prepared by this invention to possess high whiteness and high color uniformity while also possessing certain antibacterial and hydrophobic properties, and has significant application value in the field of interior coatings.

[0033] 4. By pre-wetting the sericite powder with a wetting agent to prepare a filler slurry, which is then mixed with the water-based acrylic emulsion, the coating's adhesion and gloss are significantly improved. The sericite filler also improves the strength of the polybutyl acrylate matrix. Pre-wetting the sericite powder to prepare the filler slurry ensures excellent wetting and bonding between the filler and the polybutyl acrylate emulsion matrix. The acetylene glycol polyether used as the wetting agent inherently has a defoaming function, and the subsequent addition of polydimethylsiloxane creates a synergistic effect, resulting in a more even and fine dispersion of the coating, ensuring gloss and excellent adhesion to the wall. Furthermore, the high film-forming properties of the high-whiteness sericite powder and polybutyl acrylate emulsion enhance the coating's reflectivity. The pre-dispersed filler slurry and synergistic defoaming system effectively reduce light scattering and surface defects, ultimately resulting in a smooth, high-gloss, and highly reflective coating film. This balances the coating's functionality and decorative qualities, achieving a synergistic improvement in performance.

[0034] 5. Vacuum degassing and aging processes effectively remove air bubbles from the paint, creating a dense, non-porous coating base and significantly enhancing the coating's wear resistance. Furthermore, based on the dense film structure, aging effectively improves the uniformity of the distribution of components within the paint, inhibiting color differences and partial oxidation, significantly improving the paint's color uniformity and ensuring the paint's excellent performance as an interior paint. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 The schematic diagram is a method for preparing a high-whiteness sericite water-based coating according to the present invention. DETAILED DESCRIPTION

[0036] The technical solutions of the present invention are described clearly and completely below through some embodiments and experimental examples. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0037] Reference Figure 1 The present invention provides a high-whiteness sericite water-based coating and a preparation method thereof, and the technical solution is as follows:

[0038] Example 1

[0039] The sericite ore is crushed and ground by a crushing device and a grinding device, and the ore powder with a size less than 400 mesh is selected by screening to obtain sericite ore powder.

[0040] Sericite ore powder was mixed with deionized water to prepare a pulp at a pulp concentration of 25%, and the pH was adjusted to 8 to obtain a sericite ore pulp. To 1000 parts of the sericite ore pulp were added 0.1 parts of sodium oleate, 0.2 parts of sodium silicate, and 0.05 parts of methyl isobutyl carbinol. After flotation for 10 minutes, the froth layer was collected to enrich the ore powder, which was then mixed with deionized water again to prepare a pulp concentration of 10%. After adding 0.08 wt‰ of sodium silicate, the pulp was flotated for 5 minutes, and the froth layer was collected to obtain a flotation pulp.

[0041] The flotation pulp concentration was adjusted to 25%, and magnetic separation was performed at a magnetic induction intensity of 1.2 T. The product was concentrated, filtered, and dried to obtain refined ore powder.

[0042] 200 parts of refined mineral powder are slowly added to 1000 parts of a 10% sodium sulfite aqueous solution, stirred at 300 rpm at 25°C for 20 minutes, adjusted to pH 3, heated to 60°C, stirred at 100 rpm for 60 minutes, cooled to 25°C, filtered to obtain a solid product, washed with water, and dried to obtain pre-bleached mineral powder; the ultrasonic-assisted oxidative bleaching process is as follows: 200 parts of the pre-bleached mineral powder are added to 1000 parts of a 5% hydrogen peroxide aqueous solution, adjusted to pH 9, treated at 70°C with an ultrasonic power of 250 W and an ultrasonic frequency of 30 kHz for 90 minutes, cooled to 25°C, filtered, washed with water, and dried to obtain the bleached mineral powder.

[0043] 5 parts of tetrabutyl titanate were slowly added to 50 parts of anhydrous ethanol, and stirred at 200 rpm for 30 minutes at 25°C to obtain a tetrabutyl titanate ethanol solution; the preparation process of the γ-aminopropyltriethoxysilane ethanol solution was as follows: 1 part of γ-aminopropyltriethoxysilane was slowly added to 20 parts of anhydrous ethanol, and stirred at 150 rpm for 15 minutes at 25°C to obtain a γ-aminopropyltriethoxysilane ethanol solution.

[0044] 10 parts of bleached mineral powder are added to 75 parts of deionized water, and treated at 60°C with an ultrasonic power of 220 W and an ultrasonic frequency of 25 kHz for 20 minutes. The mixture is then cooled to 50°C and continuously stirred at a speed of 500 rpm. Under nitrogen protection, a tetrabutyl titanate ethanol solution is added dropwise at a rate of 1.5 parts / min, and a γ-aminopropyltriethoxysilane ethanol solution is added dropwise at a rate of 1.2 parts / min. The addition is stopped after 70 minutes, and the mixture is cooled to 45°C and stirred at 500 rpm for 3 hours to obtain a modified mineral pulp. The modified mineral pulp is added to a hydrothermal kettle, reacted at 140°C under the autogenous pressure of the hydrothermal kettle for 10 hours, and washed and dried to obtain high-whiteness sericite powder.

[0045] 100 parts of high-whiteness sericite powder, 100 parts of deionized water and 0.5 parts of acetylene glycol polyether were mixed and stirred at a speed of 100 rpm at 25°C. Then, 0.2 parts of sodium polyacrylate and 0.5 parts of sodium fatty alcohol polyoxyethylene ether sulfate were added. The stirring speed was adjusted to 200 rpm and stirred for 20 minutes. The mixture was then treated at an ultrasonic power of 250 W and an ultrasonic frequency of 20 kHz at 40°C for 30 minutes to obtain a filler slurry.

[0046] 100 parts of filler slurry and 110 parts of polybutyl acrylate were stirred and mixed at 500 rpm at 25°C for 20 minutes, and then 0.5 parts of polydimethylsiloxane, 1 part of dipropylene glycol benzoate and 0.8 parts of isooctyl benzoate were added, and the temperature was raised to 50°C. The stirring speed was reduced to 150 rpm and mixed for 30 minutes. After cooling to 25°C, a premixed coating was obtained.

[0047] Under an operating pressure of 10 kPa, the premixed coating was degassed at a rotation speed of 200 rpm for 30 minutes to obtain a coating precursor.

[0048] The coating precursor was shaken at a rate of 10 times / min at 35°C, treated for 10 hours, and then heated to 40°C and allowed to stand for 48 hours to obtain a high-whiteness sericite water-based coating.

[0049] The prepared high-whiteness sericite water-based paint has the following parameters: whiteness WI = 93.5; color uniformity ΔE = 0.38; viscosity 945 mPa·s; density 1.24 g / mL; 60° glossiness is 17 GU; and visible light reflectivity = 89.2%.

[0050] The operating parameters of Examples 2-20 are different from those of Example 1, but the other process steps are the same. The specific changes are summarized in Tables 1 and 2.

[0051] The physical parameters of the high-whiteness sericite water-based coatings prepared in Examples 2-20 are different from those of the coating prepared in Example 1. The specific parameters are summarized in Table 3.

[0052] Table 1 Operation parameter changes of Examples 1-20 (I)

[0053]

[0054] Table 2 Operation parameter changes of Examples 1-20 (II)

[0055]

[0056] Table 3 Changes in physical parameters of the coatings prepared in Examples 1-20

[0057]

[0058] Comparative Example 1

[0059] The difference from Example 1 is that flotation is not performed, and magnetic separation is performed directly, and other process parameters remain unchanged.

[0060] Comparative Example 2

[0061] Different from Example 1, magnetic separation is not performed and other process parameters remain unchanged.

[0062] Comparative Example 3

[0063] The difference from Example 1 is that the order of magnetic separation and flotation is exchanged, and other process parameters remain unchanged.

[0064] Comparative Example 4

[0065] Different from Example 5, reductive bleaching is not performed in the sequential chemical bleaching, and other process parameters remain unchanged.

[0066] Comparative Example 5

[0067] Different from Example 5, oxidative bleaching was not performed in the sequential chemical bleaching, and other process parameters remained unchanged.

[0068] Comparative Example 6

[0069] Different from Example 5, ultrasonic assistance was not performed during the oxidative bleaching process, and other process parameters remained unchanged.

[0070] Comparative Example 7

[0071] The difference from Example 9 is that surface deposition is performed first and then grafting modification is performed, and other process parameters remain unchanged.

[0072] Comparative Example 8

[0073] The difference from Example 9 is that the grafting modification is performed first and then the surface deposition is performed, and the other process parameters remain unchanged.

[0074] Comparative Example 9

[0075] Different from Example 13, acetylene glycol polyether and polydimethylsiloxane were added simultaneously as wetting agents, and other process parameters remained unchanged.

[0076] Comparative Example 10

[0077] Different from Example 13, acetylene glycol polyether and polydimethylsiloxane were added simultaneously as defoaming agents, and other process parameters remained unchanged.

[0078] Comparative Example 11

[0079] The difference from Example 13 is that trifluoroethyl methacrylate is used as the aqueous acrylic emulsion, and the other process parameters remain unchanged.

[0080] Comparative Example 12

[0081] Different from Example 17, no vacuum degassing treatment was performed and other process parameters remained unchanged.

[0082] Comparative Example 13

[0083] The difference from Example 17 is that no aging treatment is performed and other process parameters remain unchanged.

[0084] Experimental Example 1

[0085] The whiteness and color uniformity of the sericite water-based coatings prepared in Examples 1-4 and Comparative Examples 1-3 were tested, and the relevant results are summarized in Table 4.

[0086] The whiteness test method refers to GB / T 5950-2008 standard. Cement boards that have been coated with sericite water-based paint and dried are selected as the experimental group. The film thickness is controlled to be 0.4-0.6mm, and the measurement data is expressed in WI CIE.

[0087] The color uniformity test method refers to the GB / T 11942-2022 standard. Cement boards that have been coated with sericite water-based paint and dried are selected as the experimental group. The film thickness is controlled at 0.4-0.6mm, and the measurement data is expressed as ΔE.

[0088] Table 4 Whiteness and color uniformity of the coatings prepared in Examples 1-4 and Comparative Examples 1-3

[0089] Whiteness WI Color uniformity ΔE Example 1 93.5 0.38 Example 2 92.0 0.50 Example 3 94.8 0.32 Example 4 93.2 0.35 Comparative Example 1 90.4 0.57 Comparative Example 2 89.3 0.55 Comparative Example 3 89.8 0.46

[0090] As shown in the whiteness and color uniformity data in Table 4, the coatings prepared in Examples 1-4 have a higher whiteness and a more uniform color, which directly indicates that the combined application of flotation and magnetic separation processes can effectively improve the whiteness of sericite coatings and improve their color uniformity. For Comparative Example 1, only magnetic separation was performed and the flotation process was omitted, resulting in its whiteness and color uniformity being the worst among all comparison groups, which means that some colored impurities cannot be removed by magnetic separation alone. For Comparative Example 2, only flotation was performed and the magnetic separation process was omitted, which also resulted in its whiteness and color uniformity being significantly deteriorated, which means that flotation alone cannot remove all colored impurities. Although Comparative Example 3 also performed flotation and magnetic separation, the order of its processes was changed compared to Examples 1-4, resulting in the whiteness still being low and the color uniformity still needing to be improved. In summary, the order of flotation and magnetic separation has a significant impact on the final whiteness and color uniformity. The correct process sequence is crucial. Flotation first can remove a large amount of non-magnetic impurities, reducing the complexity of the subsequent magnetic separation process. This allows the magnetic separation process to remove magnetic impurities more efficiently and accurately, and more effectively exert the synergistic effect of the two processes.

[0091] Experimental Example 2

[0092] With reference to Experimental Example 1, the coatings prepared in Examples 5-8 and Comparative Examples 4-6 were tested for whiteness and color uniformity, and the results are summarized in Table 5.

[0093] The volatile organic compound (VOC) content generated after the coatings prepared in Examples 5-8 and Comparative Examples 4-6 were dried was tested.

[0094] The test method for VOC content refers to the relevant part of water-based wall coatings in GB 18582-2020 standard.

[0095] The specific measurement parameters include: VOC content, formaldehyde content and total benzene content of interior wall paint. The results are summarized in Table 5.

[0096] Table 5 Whiteness, color uniformity and VOC content of the coatings prepared in Examples 5-8 and Comparative Examples 4-6

[0097]

[0098] As shown in Table 5 for whiteness, color uniformity, and VOC content, Examples 5-8 demonstrate significant advantages over Comparative Examples 4-6 in terms of whiteness, color uniformity, and VOC content. Comparative Example 4, which omitted reductive bleaching during the sequential chemical bleaching process, exhibited the lowest whiteness of all the groups, relatively poor color uniformity, and a VOC content similar to, but slightly higher than, that of the Example group. Comparative Example 5, which omitted oxidative bleaching during the sequential chemical bleaching process, exhibited significant increases in VOC content, particularly formaldehyde and total benzene content, which were significantly higher than those of the other groups. Furthermore, whiteness and color uniformity were poor. Comparative Example 6, which omitted ultrasonic bleaching during the oxidative bleaching process, exhibited slightly poorer whiteness and color uniformity, and its VOC content was also slightly higher than that of Examples 5-8. In summary, reductive bleaching is mainly responsible for removing key impurities that affect whiteness and color uniformity. These impurities cannot be effectively removed by simple oxidative bleaching. Oxidative bleaching is mainly responsible for removing other impurities that affect whiteness and color uniformity. It is also an important step in removing or decomposing VOC precursors. Ultrasonic assistance mainly plays a role in enhancing the efficiency and uniformity of oxidative bleaching, which can more thoroughly remove impurities and more effectively reduce VOC precursors. The results show that both reductive bleaching and oxidative bleaching are indispensable in the sequential chemical bleaching process, and the bleaching order has a significant impact on the final effect. A single bleaching step or different bleaching orders cannot achieve the optimal purification effect and coating performance.

[0099] Experimental Example 3

[0100] The coatings prepared in Examples 9-12 and Comparative Examples 7-8 were tested for antibacterial properties and hydrophobicity.

[0101] The antibacterial test method was based on GB / T 21866-2008. The hydrophobicity test used the contact angle test method. The obtained data are summarized in Table 6.

[0102] With reference to Experimental Example 1, the whiteness and color uniformity of the coatings prepared in Examples 9-12 and Comparative Examples 7-8 were tested, and the results are summarized in Table 6.

[0103] Table 6 Whiteness, color uniformity, antibacterial properties and hydrophobicity of the coatings prepared in Examples 9-12 and Comparative Examples 7-8

[0104]

[0105] As shown in the whiteness, color uniformity, antibacterial rate, and water contact angle data in Table 6, the coatings prepared in Examples 9-12 were significantly superior to Comparative Examples 7-8 in terms of multiple performance indicators, including whiteness WI value, color uniformity, antibacterial property, and water contact angle. Comparative Example 7 uses a sequential process, first depositing titanium dioxide whitening agent on the surface of the sericite mineral powder, and then performing silane grafting modification after completion of deposition. Although this can also improve the performance of the sericite mineral powder to a certain extent, the effect is far inferior to the simultaneous process. The order of deposition first and then grafting may result in insufficient bonding between the deposited layer and the sericite substrate, resulting in an insufficiently dense and uniform structure of the deposited layer, and also hindering the full realization of the synergistic effect of the two modification technologies. Comparative Example 8 also uses a sequential process, first performing silane grafting modification on the sericite mineral powder, and then performing surface deposition of titanium dioxide whitening agent after completion of grafting. As a result, the deposited layer cannot be effectively anchored on the sericite surface, and the grafted layer hinders the uniform growth of the deposited layer, which is also not conducive to the realization of the synergistic effect. In summary, simultaneous deposition and grafting modification allows for in-situ grafting modification during the deposition process, allowing silane grafting modification to occur simultaneously with titanium dioxide deposition. The grafted organosilane molecular chains intersperse between the titanium dioxide deposit layer and the sericite substrate, forming an organic-inorganic network structure. This significantly enhances the bonding between the deposit layer and the substrate, creating a denser deposit layer surface and imparting excellent antibacterial and hydrophobic properties to the sericite composite filler and coating. Combining the two independent modification steps into one simplifies the process, shortens processing time, and reduces production costs. It also significantly enhances the bonding strength and durability between the titanium dioxide deposit layer and the sericite substrate, synergistically improving the whiteness, color uniformity, antibacterial properties, and hydrophobicity of the sericite coating, giving the coating both excellent decorative and functional properties.

[0106] Experimental Example 4

[0107] With reference to Experimental Example 1, the whiteness, color uniformity, reflectivity and gloss at 60° of the coatings prepared in Examples 13-16 and Comparative Examples 9-11 were tested, and the results are summarized in Table 7.

[0108] The test method for gloss at 60° refers to GB / T 9754-2007 standard.

[0109] The test method for reflectivity refers to GB / T 23981-2009 standard.

[0110] Table 7 Whiteness, color uniformity, reflectivity and glossiness of the coatings prepared in Examples 13-16 and Comparative Examples 9-11

[0111]

[0112] As shown in Table 7 for whiteness, color uniformity, reflectivity, and gloss, Examples 12-16 demonstrate significant advantages over Comparative Examples 9-11 in terms of whiteness, color uniformity, 60° gloss, and visible light reflectivity. Comparative Example 9, in which acetylene glycol polyether and polydimethylsiloxane are added simultaneously as wetting agents to the coating system, rather than pre-mixed with sericite powder to prepare a filler slurry, fails to fully utilize their wetting and dispersing properties for the sericite powder, resulting in poor filler dispersion and, in turn, severely impacting the coating's whiteness, color uniformity, and reflectivity. Comparative Example 10, in which acetylene glycol polyether and polydimethylsiloxane are added simultaneously as defoamers to the coating system, rather than separately adding and synergizing the wetting and defoaming agents as in the previous examples, impairs the wetting and dispersing properties of the acetylene glycol polyether, resulting in suboptimal filler dispersion and film quality, which in turn impacts whiteness, color uniformity, and reflectivity. Comparative Example 11 replaces the water-based acrylic emulsion with trifluoroethyl methacrylate emulsion, which is significantly insufficient in terms of whiteness, color uniformity, and especially color uniformity. The overall performance is not as balanced and excellent as that of polybutyl acrylate emulsion. In summary, the filler slurry is prepared by mixing acetylene glycol polyether with sericite powder in advance, which significantly improves the wettability and dispersibility of sericite powder, effectively reduces the surface tension of the water-based coating, and thus improves the gloss and decorative effect of the coating film. At the same time, polydimethylsiloxane is used as a high-efficiency defoamer, and synergistically defoams with acetylene glycol polyether, comprehensively improving the coating film quality of the coating. Polybutyl acrylate emulsion has excellent film-forming properties and is easy to form a continuous, dense, and uniform coating film with good leveling properties. Its biggest disadvantage is insufficient physical strength, but sericite filler can effectively improve this. Therefore, the use of polybutyl acrylate emulsion can obtain a smooth and flat coating surface, thereby improving the gloss and reflectivity of the coating film without causing the coating film strength to be too low.

[0113] Experimental Example 5

[0114] Referring to the relevant methods of Experimental Example 1, the whiteness and color uniformity of the coatings prepared in Examples 17-20 and Comparative Examples 12-13 were tested, and the relevant results are summarized in Table 8.

[0115] The coatings prepared in Examples 17-20 and Comparative Examples 12-13 were subjected to a wear resistance test with reference to GB / T 23988-2009. The relevant results are summarized in Table 8.

[0116] Table 8 Whiteness, color uniformity and wear resistance of the coatings prepared in Examples 17-20 and Comparative Examples 12-13

[0117] Whiteness WI Color uniformity ΔE Wear resistance (L / μm) Example 17 94.4 0.35 1.2 Example 18 93.4 0.36 1.1 Example 19 92.7 0.44 1.2 Example 20 94.7 0.33 1.1 Comparative Example 12 93.2 0.61 0.7 Comparative Example 13 94.1 0.55 0.6

[0118] As shown in the whiteness, color uniformity and wear resistance data of Table 8, Examples 17-20 have good color uniformity and whiteness, and also good wear resistance. Comparative Example 12 has little effect on whiteness due to the lack of vacuum degassing treatment, but the bubble defects remaining inside the coating significantly reduce the density and structural strength of the coating, making it more susceptible to wear and damage, and the wear resistance is greatly reduced. Comparative Example 13 has poor color uniformity and wear resistance due to the lack of aging treatment. In summary, the synergistic cooperation of vacuum degassing and aging treatment can jointly improve the wear resistance of the coating. The core function of vacuum degassing is to eliminate bubbles and build a dense coating. On the basis of vacuum degassing, the aging treatment further stabilizes the coating structure, eliminates internal stress, and promotes uniform dispersion of components, thereby jointly improving the overall durability of the coating.

[0119] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a high-whiteness sericite water-based coating, characterized in that: The preparation method is as follows: Crushing and grinding the sericite ore to obtain sericite ore powder; Sequentially subjecting the sericite ore powder to flotation purification and magnetic separation purification to obtain refined ore powder; The refined mineral powder is subjected to sequential chemical bleaching to obtain bleached mineral powder; wherein the sequential chemical bleaching process includes: reductive bleaching and ultrasonic-assisted oxidative bleaching; The reductive bleaching process is as follows: 200 parts by mass of the refined mineral powder are slowly added to 1000 parts by mass of a 10% sodium sulfite aqueous solution, stirred at 300-500 rpm at 25°C for 20 minutes, adjusted to a pH of 3-5 and heated to 60°C, stirred at 100 rpm for 60 minutes, cooled to 25°C, filtered to obtain a solid product, washed with water, and dried to obtain a pre-bleached mineral powder; The ultrasonic-assisted oxidative bleaching process is as follows: adding 200 parts of the pre-bleached mineral powder to 1000 parts of a 5% hydrogen peroxide aqueous solution, adjusting the pH to 9-10, treating at 70° C. with an ultrasonic power of 250-300 W and an ultrasonic frequency of 30-40 kHz for 90 minutes, cooling to 25° C., filtering, washing, and drying to obtain the bleached mineral powder; The bleached mineral powder is surface-modified to obtain high-whiteness sericite powder; wherein the surface modification process includes surface deposition and grafting modification; the surface deposition and grafting modification are performed simultaneously; The surface modification process is as follows: 10 parts by mass of the bleached mineral powder are added to 75 parts of deionized water, and the mixture is treated at 60° C. with an ultrasonic power of 220 W and an ultrasonic frequency of 25 kHz for 20 minutes. The mixture is then cooled to 50° C. and continuously stirred at a speed of 500 rpm. Under nitrogen protection, a tetrabutyl titanate ethanol solution is added dropwise at a rate of 1.5 parts / min, and a γ-aminopropyltriethoxysilane ethanol solution is added dropwise at a rate of 1.2 parts / min. The addition is stopped after 70 minutes, the mixture is cooled to 45° C. and stirred at 500 rpm for 3 hours to obtain a modified slurry. The modified slurry is added to a hydrothermal kettle, reacted at 140° C. under the autogenous pressure of the hydrothermal kettle for 10 hours, and washed and dried to obtain the high-whiteness sericite powder. Dispersing and mixing the high-whiteness sericite powder with a dispersant, deionized water, and a wetting agent to obtain a filler slurry; Wherein, the wetting agent is acetylene glycol polyether; After mixing the filler slurry with the aqueous acrylic emulsion, adding a defoamer and a film-forming aid to mix and prepare a slurry, and vacuum degassing to obtain a coating precursor; Wherein, the aqueous acrylic emulsion is polybutyl acrylate; the defoaming agent is polydimethylsiloxane; The coating precursor is subjected to a aging treatment to obtain the high-whiteness sericite water-based coating; Calculated by weight, the high-whiteness sericite water-based paint comprises: 110-130 parts of the polybutyl acrylate and 100 parts of the filler slurry.

2. The method for preparing a high-whiteness sericite water-based paint according to claim 1, wherein: The flotation purification process is as follows: the sericite ore powder is mixed with deionized water at a pulp concentration of 25% by mass, the pH is adjusted to 8-9 to obtain sericite ore pulp, 0.1 parts of sodium oleate, 0.2 parts of sodium silicate and 0.05 parts of methyl isobutyl carbinol are added to 1000 parts of the sericite ore pulp, 10 minutes of flotation treatment is performed, the foam layer is collected to enrich the ore powder, and the ore powder is mixed with deionized water again to prepare a pulp with a pulp concentration of 10%-20%, 0.08 wt‰ of sodium silicate is added, and the flotation treatment is performed for 5 minutes, and the foam layer is collected to obtain a flotation ore pulp; the magnetic separation purification process is as follows: the flotation ore pulp concentration is adjusted to 25%-30%, magnetic separation is performed at a magnetic induction intensity of 1.2 T, and the product is concentrated, filtered and dried to obtain the refined ore powder.

3. The method for preparing a high-whiteness sericite water-based paint according to claim 1, wherein: The preparation process of the tetrabutyl titanate ethanol solution is as follows: 5 parts of tetrabutyl titanate are slowly added to 50 parts of anhydrous ethanol, and stirred at 200 rpm for 30 minutes at 25°C to obtain the tetrabutyl titanate ethanol solution; the preparation process of the γ-aminopropyl triethoxysilane ethanol solution is as follows: 1 part of γ-aminopropyl triethoxysilane is slowly added to 20 parts of anhydrous ethanol, and stirred at 150 rpm for 15 minutes at 25°C to obtain the γ-aminopropyl triethoxysilane ethanol solution.

4. The method for preparing a high-whiteness sericite water-based paint according to claim 1, wherein: The dispersant includes sodium polyacrylate and sodium fatty alcohol polyoxyethylene ether sulfate; the dispersion and mixing process is as follows: in parts by mass, 100 parts of the high-whiteness sericite powder, 100 parts of deionized water, and 0.5 parts of the acetylene glycol polyether are mixed, and the mixture is stirred at a speed of 100 rpm at 25°C, and then 0.2 parts of the sodium polyacrylate and 0.5 parts of the sodium fatty alcohol polyoxyethylene ether sulfate are added. After adjusting the stirring speed to 200 rpm and stirring for 20 minutes, the mixture is treated at an ultrasonic power of 250 W and an ultrasonic frequency of 20-30 kHz at 40°C for 30 minutes to obtain the filler slurry.

5. The method for preparing a high-whiteness sericite water-based paint according to claim 1, wherein: The film-forming aids include dipropylene glycol benzoate and isooctyl benzoate; the mixing and slurrying process is as follows: in parts by mass, 100 parts of the filler slurry and 110-130 parts of the polybutyl acrylate are stirred and mixed at a speed of 500 rpm at 25°C for 20 minutes, 0.5 parts of the polydimethylsiloxane, 1 part of the dipropylene glycol benzoate and 0.8 parts of the isooctyl benzoate are added, and then the temperature is raised to 50°C, the stirring speed is reduced to 150-200 rpm, and the mixture is mixed for 30 minutes, and the mixture is cooled to 25°C to obtain a premixed coating; the vacuum degassing process is as follows: under an operating pressure of 20 kPa, the premixed coating is degassed at a speed of 200-250 rpm for 30 minutes to obtain the coating precursor.

6. The method for preparing a high-whiteness sericite water-based paint according to claim 1, wherein: The aging process is as follows: shaking the coating precursor at 35° C. at a rate of 10 times / min, heating it to 40° C. for 10 hours, and then standing it for 48 hours to obtain the high-whiteness sericite water-based coating.

7. A high-whiteness sericite water-based paint, characterized by: The high-whiteness sericite water-based coating is prepared by the preparation method according to any one of claims 1 to 6; The high-whiteness sericite water-based paint comprises: high-whiteness sericite powder, a dispersant, a wetting agent, a water-based acrylic emulsion, a defoaming agent and a film-forming aid.

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