High-whiteness sericite water-based paint and preparation method thereof

Abstract

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. The invention aims to solve the problem of insufficient functionality of the existing high-whiteness sericite coating. The method comprises the following steps: crushing and grinding raw ore of sericite to obtain sericite ore powder, and sequentially carrying out flotation purification and magnetic separation purification to obtain refined ore powder; performing sequential chemical bleaching and synchronous surface deposition and grafting modification on the refined mineral powder to obtain high-whiteness sericite powder; and mixing the high-whiteness sericite powder with a water-based acrylic emulsion and an auxiliary agent, and carrying out vacuum defoaming and curing treatment to obtain the high-whiteness sericite water-based paint. The high-whiteness sericite water-based paint prepared by the invention has high whiteness and high color uniformity, is excellent in wear resistance, has certain antibacterial and hydrophobic properties, and is suitable for being used as an indoor paint.

Description

Technical Field

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

[0002] As a natural mineral, sericite has a long history of application. In modern times, as a coating filler with excellent performance, sericite is widely used in architectural coatings, anti-corrosion coatings, road sign coatings, ship industrial coatings and other fields.

[0003] In recent years, water-based coatings with sericite as filler have attracted more and more attention from the industry as a new type of coating that is both environmentally friendly and functional. Among them, high-whiteness sericite powder can significantly improve the whiteness and brightness of the coating. Its flaky structure can give the coating excellent gloss, and at the same time it can have excellent weather resistance and is not easy to produce pollutants.

[0004] As society's requirements for environmentally friendly coatings continue to increase, the market demand for high-quality, functional, and environmentally friendly water-based sericite coatings continues to grow. Although existing sericite coatings have many excellent properties, it is difficult to have both high whiteness and other functionalities at the same time. Sericite treated with high whiteness is generally difficult to modify, and thus cannot have more types of functionality. If other whitening agents are simply added to the coating, the gloss and environmental friendliness of the original sericite coating will be negatively affected while the process complexity increases.

[0005] At present, the insufficient functionality of existing high-whiteness sericite coatings remains a major challenge 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 object of the present invention is to provide a high-whiteness sericite water-based paint and a preparation method thereof. The present invention crushes and grinds sericite raw ore to obtain sericite ore powder, and sequentially performs flotation purification and magnetic separation purification to obtain refined ore powder; sequentially chemically bleaching and synchronously performs surface deposition and grafting modification on the refined ore powder 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 the high-whiteness sericite water-based paint.

[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] The sericite ore powder was mixed with deionized water to prepare pulp, and the pulp concentration was 25%, and the pH was adjusted to 8-9 to obtain the sericite ore pulp. 0.1 parts of sodium oleate, 0.2 parts of sodium silicate and 0.05 parts of methyl isobutyl carbinol were added to 1000 parts of sericite ore pulp, and the ore powder was enriched in the foam layer after flotation treatment for 10 minutes, and the ore powder was mixed with deionized water again to prepare pulp, and the ore pulp concentration was 10%-20%. After adding 0.08wt‰ of sodium silicate, the flotation treatment was carried out for 5 minutes, and the froth layer was taken to obtain the flotation ore pulp.

[0013] The flotation pulp concentration is adjusted to 25%-30%, and magnetic separation is carried out at a magnetic induction intensity of 1.2T. 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] The 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 defoamer and a film-forming aid are added to mix and 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: slowly adding 200 parts of refined mineral powder to 1000 parts of sodium sulfite aqueous solution with a mass concentration of 10%, stirring at a speed of 300-500rpm for 20 minutes at 25°C, adjusting the pH to 3-5 and heating to 60°C, stirring at a speed of 100rpm for 60 minutes, cooling to 25°C, filtering to obtain a solid product, washing with water and drying to obtain a pre-bleached mineral powder; the ultrasonic-assisted oxidative bleaching process is: adding 200 parts of pre-bleached mineral powder to 1000 parts of hydrogen peroxide aqueous solution with a mass concentration of 5%, adjusting the pH to 9-10, treating at 70°C with an ultrasonic power of 250-300W and an ultrasonic frequency of 30-40kHz for 90 minutes, cooling to 25°C, filtering, washing with water and drying to obtain a 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: adding 10 parts of bleached mineral powder to 75 parts of deionized water, treating at 60°C with an ultrasonic power of 220W and an ultrasonic frequency of 25kHz for 20min, cooling to 50°C and continuously stirring at a speed of 500rpm, adding tetrabutyl titanate ethanol solution at a rate of 1.5 parts / min under nitrogen protection, and simultaneously adding γ-aminopropyltriethoxysilane ethanol solution at a rate of 1.2 parts / min, stopping the dropping after 70min, cooling to 45°C and stirring at 500rpm for 3 hours to obtain a modified slurry; adding the modified slurry to a hydrothermal kettle, reacting at 140°C with the autogenous pressure of the hydrothermal kettle for 10 hours, washing and drying to obtain high-whiteness sericite powder.

[0022] Preferably, the preparation process of tetrabutyl titanate ethanol solution is: slowly add 5 parts of tetrabutyl titanate to 50 parts of anhydrous ethanol, stir at 200 rpm for 30 minutes at 25°C to obtain tetrabutyl titanate ethanol solution; the preparation process of γ-aminopropyl triethoxysilane ethanol solution is: slowly add 1 part of γ-aminopropyl triethoxysilane to 20 parts of anhydrous ethanol, stir at 150 rpm for 15 minutes at 25°C to obtain 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, stirred at a speed of 100 rpm at 25°C, then 0.2 parts of sodium polyacrylate and 0.5 parts of sodium polyoxyethylene fatty alcohol ether sulfate are added, 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 at a speed of 500rpm for 20 minutes, 0.5 parts of polydimethylsiloxane, 1 part of dipropylene glycol benzoate and 0.8 parts of isooctyl benzoate are added, and the temperature is raised to 50°C, the stirring speed is reduced to 150-200rpm and mixed for 30 minutes, and the premixed coating is obtained after cooling to 25°C.

[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: the coating precursor is shaken at a rate of 10 times / min at 35°C, and after treatment for 10 hours, the temperature is raised to 40°C and allowed to stand 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 defoamer 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 820-1020mPa·s; density 1.18-1.24g / mL; 60° glossiness 15-20GU; visible light band 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 subjected to flotation purification and magnetic separation in sequence. While effectively removing gangue minerals such as quartz and feldspar in the sericite ore, magnetic minerals such as hematite and magnetite are also efficiently separated. The flotation and magnetic separation of sericite ore powder in sequence ensures the graded removal of impurities and reduces the negative impact of colored impurities and magnetic impurities on the whiteness of sericite powder.

[0031] 2. The process of sequential chemical bleaching is used to carry out reductive bleaching and ultrasonic-assisted oxidative bleaching on the refined mineral powder after magnetic separation. After removing some weak coloring impurities such as iron oxides in advance, the residual organic matter and strong coloring impurities are further removed, and the bleaching effect is enhanced by ultrasonic assistance, which improves the bleaching efficiency and uniformity, and greatly improves the whiteness and color uniformity of the finished paint. In addition, the effective removal of impurities ensures the environmental protection of the paint product, and almost no organic pollutants are generated during use, making it suitable as an indoor paint.

[0032] 3. The bleached mineral powder after sequential chemical bleaching is subjected to synchronous surface deposition and grafting modification. Through process synergy and complementary material properties, the titanium dioxide whitening agent is deposited on the mineral powder surface and the surface silane grafting modification is completed simultaneously, the bonding force between the deposited layer and the sericite substrate is enhanced, and the growth process and microstructure of the deposited layer are regulated in situ, which significantly improves the density and uniformity of the deposited layer. At the same time, the synchronous execution of the two processes forms an organic-inorganic composite structure in the deposited layer, which gives the sericite filler excellent compatibility with the coating matrix, and on this basis expands a series of functionalities of the coating, so that the sericite coating prepared by the present invention has high whiteness and high color uniformity, as well as certain antibacterial and hydrophobic properties, and has significant application value in the field of indoor coatings.

[0033] 4. By using a wetting agent and high-whiteness sericite powder to prepare a filler slurry in advance, and then mixing it with a water-based acrylic emulsion, the adhesion and glossiness of the paint are significantly improved, and the strength of the polybutyl acrylate matrix is ​​improved by the sericite filler. By pre-wetting the sericite powder to prepare the filler slurry, excellent wetting and bonding between the filler and the polybutyl acrylate emulsion matrix are ensured. At the same time, the acetylene glycol polyether selected as the wetting agent itself has a defoaming function, and the polydimethylsiloxane added later forms a good synergistic effect with it, making the paint dispersion more uniform and delicate, ensuring the gloss and excellent adhesion of the paint on the wall. At the same time, the high film-forming properties of high-whiteness sericite powder and polybutyl acrylate emulsion improve the reflectivity of the paint, and the pre-dispersed filler slurry and synergistic defoaming system effectively reduce light scattering and surface defects, and finally obtain a smooth, high-gloss, high-reflectivity coating film, taking into account the functionality and decorativeness of the paint, and achieving a synergistic improvement in performance.

[0034] 5. Through vacuum degassing and aging treatment, bubbles in the paint are efficiently removed, a dense and non-porous coating film base is constructed, and the wear resistance of the coating can be significantly enhanced. At the same time, based on the dense film structure, the aging treatment can effectively improve the uniformity of the distribution of each component in the paint, inhibit the occurrence of color difference and partial oxidation, significantly improve the color uniformity of the paint, and ensure the good performance of the paint product as an indoor 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 solution of the present invention will be clearly and completely described below through some embodiments and experimental examples. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] Reference Figure 1 The principle diagram shown in the figure, the present invention provides a high whiteness sericite water-based coating and a preparation method thereof, and the technical scheme 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] The sericite ore powder was mixed with deionized water to prepare pulp, and the pulp concentration was 25%, and the pH was adjusted to 8 to obtain the sericite ore pulp. 0.1 parts of sodium oleate, 0.2 parts of sodium silicate and 0.05 parts of methyl isobutyl carbinol were added to 1000 parts of sericite ore pulp, and the ore powder was enriched in the foam layer after flotation treatment for 10 minutes, and the ore powder was mixed with deionized water again to prepare pulp, and the pulp concentration was 10%. After adding 0.08wt‰ of sodium silicate, the flotation treatment was carried out for 5 minutes, and the flotation ore pulp was obtained by taking the foam layer.

[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 sodium sulfite aqueous solution with a mass concentration of 10%, stirred at 300 rpm for 20 minutes at 25°C, adjusted to pH 3 and heated to 60°C, stirred at 100 rpm for 60 minutes, cooled to 25°C and filtered to obtain a solid product, washed with water and dried to obtain pre-bleached mineral powder; the process of ultrasonic-assisted oxidative bleaching is as follows: 200 parts of pre-bleached mineral powder are added to 1000 parts of hydrogen peroxide aqueous solution with a mass concentration of 5%, 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 and filtered, washed with water and dried to obtain bleached mineral powder.

[0043] Slowly add 5 parts of tetrabutyl titanate to 50 parts of anhydrous ethanol, stir at 200 rpm for 30 minutes at 25°C to obtain a tetrabutyl titanate ethanol solution; the preparation process of the γ-aminopropyl triethoxysilane ethanol solution is as follows: slowly add 1 part of γ-aminopropyl triethoxysilane to 20 parts of anhydrous ethanol, stir at 150 rpm for 15 minutes at 25°C to obtain a γ-aminopropyl triethoxysilane ethanol solution.

[0044] 10 parts of bleached ore 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. After cooling to 50°C, stirring is continued 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. After cooling to 45°C and stirring is maintained at 500 rpm for 3 hours, a modified ore pulp is obtained. The modified ore pulp is added to a hydrothermal kettle, reacted at 140°C with the autogenous pressure of the hydrothermal kettle for 10 hours, and high-whiteness sericite powder is obtained after washing and drying.

[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, and the stirring speed was adjusted to 200 rpm and stirred for 20 minutes. Then, the mixture was 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 for 20 minutes at 25°C, 0.5 parts of polydimethylsiloxane, 1 part of dipropylene glycol benzoate and 0.8 parts of isooctyl benzoate were added, the temperature was raised to 50°C, the stirring speed was reduced to 150 rpm and mixed for 30 minutes, and the premixed coating was obtained after cooling to 25°C.

[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, and after being treated for 10 hours, the temperature was raised 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 945mPa·s; density 1.24g / mL; 60° glossiness 17GU; visible light band reflectivity = 89.2%.

[0050] The operating parameters of Examples 2-20 are different from those of Example 1, and 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 coating prepared in Examples 2-20 are different from those of the coating prepared in Example 1, and 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 is not performed in the sequential chemical bleaching, and other process parameters remain unchanged.

[0068] Comparative Example 6

[0069] Different from Example 5, no ultrasonic assistance is performed during the oxidative bleaching process, and other process parameters remain 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 are added simultaneously as wetting agents, and other process parameters remain 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 other process parameters remain unchanged.

[0080] Comparative Example 12

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

[0082] Comparative Example 13

[0083] Different from Example 17, 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. The cement board that was painted with sericite water-based paint and dried was selected as the experimental group. The film thickness was controlled to be 0.4-0.6mm, and the measurement data was expressed in WI CIE.

[0087] The test method for color uniformity refers to GB / T 11942-2022 standard. The cement board that was coated with sericite water-based paint and dried was selected as the experimental group. The film thickness was controlled to 0.4-0.6mm, and the measurement data was expressed by 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 of 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 the worst whiteness and color uniformity 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 a significant deterioration in whiteness and color uniformity, which means that only flotation cannot remove all colored impurities. Although Comparative Example 3 also performed flotation and magnetic separation, the order of its processes changed relative to Examples 1-4, resulting in a low whiteness and a color uniformity that still needs 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. The magnetic separation process can remove magnetic impurities more efficiently and accurately, and more effectively exert the synergistic effect of the two processes.

[0091] Experimental Example 2

[0092] Referring 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 content of benzene series 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] According to the data of whiteness, color uniformity and VOC content shown in Table 5, Examples 5-8 show significant advantages in whiteness, color uniformity and VOC content of sericite coatings compared with Comparative Examples 4-6. Comparative Example 4 has the lowest whiteness among all groups due to the lack of reductive bleaching in the sequential chemical bleaching, and its color uniformity is relatively poor, and its VOC content is close to but slightly higher than that of the embodiment group. Comparative Example 5 does not perform oxidative bleaching in the sequential chemical bleaching, and various indicators of VOC content are significantly increased, especially the formaldehyde content and the total content of benzene series are much higher than other groups, and the whiteness and color uniformity are poor. Comparative Example 6 does not perform ultrasonic assistance during the oxidative bleaching process, and its whiteness and color uniformity are slightly poor, and its VOC content is also increased relative to 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 link in removing or decomposing VOC precursors. Ultrasonic assistance mainly plays a role in enhancing the efficiency and uniformity of oxidative bleaching, which can remove impurities more thoroughly and reduce VOC precursors more effectively. 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 a different bleaching order cannot achieve the best 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, and the hydrophobicity test used the contact angle test method. The obtained data are summarized in Table 6.

[0102] Referring 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 data of whiteness, color uniformity, antibacterial rate and water contact angle in Table 6, the coatings prepared in Examples 9-12 are significantly better than Comparative Examples 7-8 in terms of whiteness WI value, color uniformity, antibacterial property and water contact angle. Comparative Example 7 adopts a sequential process, first depositing titanium dioxide whitening agent on the surface of sericite mineral powder, and then performing silane grafting modification after the deposition is completed. Although it can also improve the performance of sericite mineral powder to a certain extent, the effect is far less than the synchronous process. The order of first deposition and then grafting may lead to insufficient bonding between the deposited layer and the sericite substrate, and the structure of the deposited layer is not dense and uniform enough, and it is also not conducive to giving full play to the synergistic effect of the two modification technologies. Comparative Example 8 also adopts a sequential process, first performing silane grafting modification on the sericite mineral powder, and then performing surface deposition of titanium dioxide whitening agent after the grafting is completed, resulting in the deposited layer being unable to 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 synergistic effect. In summary, simultaneous deposition and grafting modification can introduce grafting modification in situ during the deposition process, so that silane grafting modification and titanium dioxide deposition occur simultaneously, and the grafted organic silane molecular chains are interspersed between the titanium dioxide deposition layer and the sericite substrate to form an organic-inorganic network structure, which significantly enhances the bonding between the deposition layer and the substrate, generates a denser deposition layer surface, and gives the sericite composite filler and coating excellent antibacterial and hydrophobic properties. Combining two independent modification steps into one simplifies the process flow, shortens the processing time, reduces production costs, and significantly enhances the bonding strength and durability between the titanium dioxide deposition layer and the sericite substrate, synergistically improving the whiteness, color uniformity, antibacterial and hydrophobic properties of the sericite coating, so that the coating has both excellent decorative and functional properties.

[0106] Experimental Example 4

[0107] Referring 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 the whiteness, color uniformity, reflectivity and glossiness data of Table 7, Examples 12-16 show significant advantages over Comparative Examples 9-11 in terms of whiteness, color uniformity, 60° glossiness and reflectivity in the visible light band of the sericite coating. Comparative Example 9 adds acetylene glycol polyether and polydimethylsiloxane as wetting agents to the coating system at the same time, instead of pre-mixing with sericite powder to prepare filler slurry, which fails to give full play to its role in wetting and dispersing sericite powder, resulting in poor filler dispersion, which seriously affects the whiteness, color uniformity and reflectivity of the coating. Comparative Example 10 adds acetylene glycol polyether and polydimethylsiloxane as defoamers to the coating system at the same time, instead of adding and using the wetting agent and defoamer separately and in coordination as in the example, which affects the wetting and dispersing effect of acetylene glycol polyether, resulting in poor filler dispersion and coating film quality, thereby affecting whiteness, color uniformity and reflectivity. Comparative Example 11 replaces the water-based acrylic emulsion with trifluoroethyl methacrylate emulsion, and the performance in whiteness, color uniformity, especially color uniformity is obviously insufficient, and the overall performance is not as balanced and excellent as that of polybutyl acrylate emulsion. In summary, the acetylene glycol polyether is mixed with sericite powder to prepare filler slurry in advance, which significantly improves the wettability and dispersibility of sericite powder, effectively reduces the surface tension of water-based coatings, 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 acetylene glycol polyether cooperates with defoaming to comprehensively improve the coating film quality of the coating. Butyl acrylate emulsion has excellent film-forming properties, is easy to form a continuous, dense, uniform coating film, and has 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 smooth coating surface, thereby improving the gloss and reflectivity of the coating film, and will not cause the coating film strength to be too low.

[0113] Experimental Example 5

[0114] Referring to the relevant method 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 tested for abrasion resistance with reference to GB / T 23988-2009, and the relevant results are summarized in Table 8.

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

[0117] Whiteness WI Color uniformity ΔE Wear resistance (L / μm) Embodiment 17 94.4 0.35 1.2 Embodiment 18 93.4 0.36 1.1 Embodiment 19 92.7 0.44 1.2 Embodiment 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. Since Comparative Example 12 does not undergo vacuum degassing treatment, it has little effect on whiteness, 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. Since Comparative Example 13 does not undergo aging treatment, the color uniformity and wear resistance of the coating are both deteriorated. In summary, the synergistic combination 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] Although 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 the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present 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 mineral powder to flotation purification and magnetic separation purification to obtain refined mineral 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 bleached mineral powder is subjected to surface modification 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; Dispersing and mixing the high-whiteness sericite powder with a dispersant, deionized water and a wetting agent to obtain a filler slurry; 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 performing vacuum degassing to obtain a coating precursor; The coating precursor is subjected to a aging treatment to obtain the high-whiteness sericite water-based coating.

2. The method for preparing a high-whiteness sericite water-based coating according to claim 1, characterized in that: The flotation purification process is as follows: the sericite ore powder is mixed with deionized water to prepare pulp 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, the foam layer is taken to enrich the ore powder after flotation treatment for 10 minutes, and the ore powder is mixed with deionized water again to prepare pulp, the pulp concentration is 10%-20%, 0.08wt‰ of sodium silicate is added, the flotation treatment is carried out for 5 minutes, and the foam layer is taken to obtain the flotation ore pulp; the magnetic separation purification process is as follows: the flotation ore pulp concentration is adjusted to 25%-30%, magnetic separation is carried out at a magnetic induction intensity of 1.2T, 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 coating according to claim 1, characterized in that: The reductive bleaching process is as follows: by weight, 200 parts of the refined mineral powder are slowly added to 1000 parts of a sodium sulfite aqueous solution with a mass concentration of 10%, stirred at a speed of 300-500rpm for 20min at 25°C, adjusted to a pH of 3-5 and heated to 60°C, stirred at a speed of 100rpm for 60min, 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: 200 parts of the pre-bleached mineral powder are added to 1000 parts of a hydrogen peroxide aqueous solution with a mass concentration of 5%, adjusted to a pH of 9-10, treated at 70°C with an ultrasonic power of 250-300W and an ultrasonic frequency of 30-40kHz for 90min, cooled to 25°C, filtered, washed with water and dried to obtain the bleached mineral powder.

4. The method for preparing a high-whiteness sericite water-based coating according to claim 1, characterized in that: The surface modification process is as follows: by weight, 10 parts of the bleached mineral powder are added to 75 parts of deionized water, treated at 60°C with an ultrasonic power of 220W and an ultrasonic frequency of 25kHz for 20 minutes, cooled to 50°C and continuously stirred at a speed of 500rpm, and under nitrogen protection, tetrabutyl titanate ethanol solution is added dropwise at a speed of 1.5 parts / min, and γ-aminopropyl triethoxysilane ethanol solution is added dropwise at a speed of 1.2 parts / min, and the addition is stopped after 70 minutes, and the temperature is cooled to 45°C and stirred at 500rpm for 3 hours to obtain a modified ore pulp; the modified ore pulp is added to a hydrothermal kettle, The reaction is carried out at 140°C under the autogenous pressure of a hydrothermal autoclave for 10 hours, and the high-whiteness sericite powder is obtained after washing and drying; wherein, the preparation process of the tetrabutyl titanate ethanol solution is: 5 parts of tetrabutyl titanate are slowly added to 50 parts of anhydrous ethanol, and stirred at a speed of 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: 1 part of γ-aminopropyl triethoxysilane is slowly added to 20 parts of anhydrous ethanol, and stirred at a speed of 150 rpm for 15 minutes at 25°C to obtain the γ-aminopropyl triethoxysilane ethanol solution.

5. The method for preparing a high-whiteness sericite water-based paint according to claim 1, characterized in that: The dispersant comprises sodium polyacrylate and sodium polyoxyethylene fatty alcohol ether sulfate; the wetting agent is acetylene glycol polyether; the dispersing and mixing process is as follows: by weight, 100 parts of the high-whiteness sericite powder, 100 parts of deionized water and 0.5 parts of the acetylene glycol polyether are mixed, stirred at a speed of 100 rpm at 25°C, then 0.2 parts of the sodium polyacrylate and 0.5 parts of the sodium polyoxyethylene fatty alcohol ether sulfate are added, 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 the filler slurry.

6. The method for preparing a high-whiteness sericite water-based paint according to claim 1, characterized in that: The aqueous acrylic emulsion is polybutyl acrylate; the defoaming agent is polydimethylsiloxane; the film-forming aid includes dipropylene glycol benzoate and isooctyl benzoate; the mixing and slurrying process is: 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 the temperature is raised to 50°C, the stirring speed is reduced to 150-200rpm and mixed for 30 minutes, and the premixed coating is obtained after cooling to 25°C; the vacuum degassing process is: under an operating pressure of 20kPa, the premixed coating is degassed at a speed of 200-250rpm for 30 minutes to obtain the coating precursor.

7. The method for preparing a high-whiteness sericite water-based paint according to claim 1, characterized in that: The aging treatment process is: 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 the high-whiteness sericite water-based coating.

8. A high whiteness sericite water-based paint, characterized in that: The high-whiteness sericite water-based paint is prepared by the preparation method according to any one of claims 1 to 7; 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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