Reflective thermal insulation sand wall paint, preparation method and application thereof

Abstract

The application belongs to the technical field of building coatings, and more particularly relates to a reflective heat-insulating sand wall paint, a preparation method and application thereof. The reflective heat-insulating sand wall paint provided by the application can obviously improve the stability of the modified composite emulsion and the color stability and pigment adhesion of the reflective heat-insulating sintered colored sand by introducing modified silica sol into the composite emulsion and the reflective heat-insulating sintered colored sand and regulating the proportion of the modified silica sol and other components. Through the synergistic effect between the components, the coating formed by coating the reflective heat-insulating sand wall paint on the surface of a building has high ultraviolet light absorption ratio and near-infrared reflection ratio, good reflective heat-insulating performance, excellent weather resistance and stain resistance, and more durable reflective heat-insulating effect.

Description

Technical Field

[0001] This application belongs to the field of architectural coatings technology, and more specifically, relates to a reflective heat-insulating sand wall paint, its preparation method and application. Background Technology

[0002] Currently, building energy conservation has received widespread attention from the whole society. Improving the thermal insulation performance of buildings is an important way to save energy and improve the functionality of buildings. Reflective thermal insulation coatings for buildings effectively reflect solar heat radiation in summer, reducing the absorption of solar radiation energy by the building surface. After applying this type of coating to the exterior wall, the surface temperature of the coating film will not rise significantly, thus reducing the heat transferred into the building through the wall. Currently, most reflective thermal insulation coatings for buildings are acrylic resin emulsion coatings, which have poor stain resistance. As the coating layer is used for a longer period of time, the heat reflection effect of the coating decreases significantly. In some cities with severe air pollution, the heat reflection effect of the coating will decrease by 50% in less than two years, and its aging resistance is also poor. Therefore, in addition to good thermal insulation performance, reflective thermal insulation coatings for buildings should also have excellent stain resistance and aging resistance to improve the durability of the coating's thermal insulation effect. Summary of the Invention

[0003] In view of the shortcomings of the prior art, the purpose of this application is to provide a reflective heat-insulating sand wall paint, its preparation method and application, which aims to solve the problems of poor storage stability, stain resistance and aging resistance of existing reflective heat-insulating coatings, and low durability of the heat insulation effect of the coatings.

[0004] To achieve the above objectives, in a first aspect, this application provides a reflective heat-insulating sand-textured wall paint, which comprises the following components and their mass fractions: 650-750 parts reflective heat-insulating sintered colored sand, 120-160 parts modified composite emulsion, 5-15 parts coating additives and 100-150 parts water; The aforementioned reflective heat-insulating sintered colored sand includes modified silica sol, sodium silicate, quartz sand, reflective heat-insulating pigment and flux, and the mass ratio of modified silica sol, sodium silicate, quartz sand, reflective heat-insulating pigment and flux is 1:(8~12):(500~800):(3~7):(0.5~1); The modified composite emulsion mentioned above includes a modified acrylic emulsion, an acid-base regulator, a film-forming aid, a multifunctional aid, and a defoamer, and the mass ratio of the modified acrylic emulsion, the acid-base regulator, the film-forming aid, the multifunctional aid, and the defoamer is 100:(2~4):(3~5):(1~2):(1~2); The modified acrylate emulsion described above is prepared by polymerization reaction of acrylic monomers, water-soluble polymers and the modified silica sol described above, under the action of an initiator.

[0005] Preferably, the mass percentage of silica in the modified silica sol is 20% to 30%.

[0006] Preferably, the modified silica sol is obtained by heating and mixing nano-silica, coupling agent and solvent and then concentrating.

[0007] Preferably, the particle size of the above-mentioned nano-silica is 5nm~60nm.

[0008] Preferably, the coupling agent is a silane coupling agent, selected from one or more of silane coupling agents KH-550, KH-560, and KH-570.

[0009] Preferably, the dispersant is one or more of N-methylpyrrolidone, α-pyrrolidone, and N-vinylpyrrolidone.

[0010] Preferably, the modulus of the sodium silicate is 3.0 to 3.5.

[0011] Preferably, the water-soluble polymer is cellulose or a derivative thereof. More preferably, the water-soluble polymer is selected from one or more of cellulose, hydroxymethylcellulose, hydroxyethylmethylcellulose, hydroxyethylethylcellulose, and hydroxypropylmethylcellulose.

[0012] Preferably, the acrylic monomers mentioned above are at least two of acrylic acid, methacrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, isooctyl acrylate, and methyl methacrylate.

[0013] Preferably, the initiator is one or more of ammonium persulfate, potassium persulfate, azobisisobutyronitrile, and azobiscyanopentanoic acid.

[0014] Preferably, in the modified acrylate emulsion, the mass ratio of the water-soluble polymer to the silica in the modified silica sol is 1:(8~12).

[0015] Preferably, the modified silica content in the modified acrylate emulsion is 5wt% to 15wt% of the total mass of acrylic monomers.

[0016] Preferably, the amount of the initiator added is 0.5wt% to 5wt% of the total mass of the acrylic monomers.

[0017] Preferably, the mesh size of the quartz sand is 40 to 120 mesh.

[0018] Preferably, the aforementioned reflective heat-insulating pigment is one or more of reflective heat-insulating titanium dioxide, reflective heat-insulating red pigment, reflective heat-insulating yellow pigment, and reflective heat-insulating black pigment.

[0019] Preferably, the co-solvent is one or more of condensed aluminum phosphate, sodium fluorosilicate, and silicon tripolyphosphate.

[0020] Preferably, the acid-base regulator is one or more of sodium hydroxide solution and ammonia solution.

[0021] Preferably, the film-forming aid is one or more of alcohol-based film-forming aids, alcohol ester-based film-forming aids, alcohol ether-based film-forming aids, and alcohol ether ester-based film-forming aids.

[0022] Preferably, the defoamer is one or more of mineral oil-based defoamers, silicone-based defoamers, and polyether-based defoamers.

[0023] Preferably, the above-mentioned coating additives include one or more of thickeners, bactericides, and anti-settling agents.

[0024] Secondly, this application provides a method for preparing the above-mentioned reflective heat-insulating sand wall paint, comprising the following steps: S1. The modified silica sol, sodium silicate, quartz sand, reflective heat-insulating pigment and flux are mixed according to the above ratio and then sintered to obtain reflective heat-insulating sintered colored sand. S2. Mix the modified acrylic emulsion, acid-base regulator, film-forming aid, multifunctional aid and defoamer according to the formula to obtain the modified composite emulsion. S3. Mix the above-mentioned reflective heat-insulating sintered colored sand, the above-mentioned modified composite emulsion, coating additives and water according to the formula to obtain reflective heat-insulating sand wall paint.

[0025] Thirdly, this application provides a reflective heat-insulating coating, which is obtained by applying the above-mentioned reflective heat-insulating sand wall paint to the surface of a substrate and then drying it completely.

[0026] In summary, compared with the prior art, the technical solutions conceived in this application have the following main technical advantages: The reflective heat-insulating sand-textured wall paint provided in this application significantly improves the stability of the modified composite emulsion by introducing modified silica sol into the composite emulsion and the reflective heat-insulating sintered colored sand and adjusting the ratio of modified silica sol to other components. Simultaneously, the modified silica sol exhibits good dispersibility in the composite emulsion, increasing the microscopic surface roughness of the film after film formation, thereby enhancing the hydrophilicity of the coating and improving its stain resistance in outdoor applications. Furthermore, the prepared reflective heat-insulating sintered colored sand exhibits superior color stability and stronger pigment adhesion, further improving its reflective heat-insulating performance. By compounding reflective heat-insulating sintered colored sand, modified composite emulsion, and coating additives, the resulting reflective heat-insulating sand-textured wall paint, when applied to building surfaces, forms a coating with high ultraviolet light absorption and near-infrared reflectance, resulting in excellent reflective heat-insulating performance. Moreover, the gradation combination of the aforementioned reflective heat-insulating sintered colored sand ensures a smooth and dense coating surface with few pores, making it difficult for fine dust particles to penetrate the pores, thus exhibiting excellent stain resistance and weather resistance, and ensuring long-lasting reflective heat-insulating effects. Attached Figure Description

[0027] Figure 1 This is a schematic flowchart of the preparation method of the reflective heat-insulating sand wall paint provided in the embodiments of this application; Figure 2 It is the color fastness of the reflective heat-insulating sintered colored sand sample prepared in the embodiments of this application. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0029] In the description of this application, it should be understood that the term "and / or" describes a relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. The symbol " / " in this document indicates that the related objects are in an "or" relationship; for example, A / B means A or B.

[0030] This application provides a reflective heat-insulating sand-wall paint, which comprises the following components and their mass fractions: 650-750 parts reflective heat-insulating sintered colored sand, 120-160 parts modified composite emulsion and 5-15 parts coating additives; The aforementioned reflective heat-insulating sintered colored sand includes modified silica sol, sodium silicate, quartz sand, reflective heat-insulating pigment and flux, and the mass ratio of modified silica sol, sodium silicate, quartz sand, reflective heat-insulating pigment and flux is 1:(8~12):(500~800):(3~7):(0.5~1); The modified composite emulsion mentioned above includes modified acrylic emulsion, acid-base regulator, film-forming aid, multifunctional aid and defoamer, and the mass ratio of modified acrylic emulsion, acid-base regulator, film-forming aid, multifunctional aid and defoamer is 100:(2~4):(3~5):(1~2):(1~2); The modified acrylate emulsion described above is prepared by polymerization reaction of acrylic monomers, water-soluble polymers and the modified silica sol described above, under the action of an initiator.

[0031] In some embodiments, the modified silica content in the modified silica sol is 20% to 30% by mass.

[0032] This application does not limit the preparation method of the modified silica sol, such as, but not limited to, heating and mixing nano-silica, coupling agent, and dispersant and then concentrating them. This application does not limit the ratio between nano-silica, coupling agent, and dispersant; as long as the nano-silica can be completely modified, it is within the scope of protection of this application.

[0033] In some embodiments, the particle size of the above-mentioned nano-silica is 5~60nm, preferably 10~50nm.

[0034] In some embodiments, to reduce the preparation difficulty and improve the dispersibility of silica in the modified silica sol, commercially available nano-silica dispersions can be selected and mixed with coupling agents and dispersants to prepare the modified silica sol. In some embodiments, the aforementioned silica dispersions can be, but are not limited to, Mesh V-820 nano-silica dispersions, Aurun 308 nano-silica dispersions, and CH83-123 nano-silica dispersions.

[0035] In some embodiments, the coupling agent is a silane coupling agent, selected from one or more of the silane coupling agents KH-550, KH-560, and KH-570.

[0036] In some embodiments, the dispersant is one or more of N-methylpyrrolidone, α-pyrrolidone, and N-vinylpyrrolidone.

[0037] In some embodiments, the modulus of the sodium silicate is 3.0 to 3.5, for example, but not limited to 3.0, 3.2, 3.4, and 3.5. The inventors of this application have discovered through experiments that the inorganic resin prepared by combining the modified silica sol and components such as sodium silicate, quartz sand, reflective heat-insulating pigments, and co-solvents of suitable modulus exhibits excellent bonding properties and strong adhesion.

[0038] In some embodiments, the mesh size of the quartz sand is 40 to 120 mesh. For example, the mesh size of the quartz sand can be 40 mesh, 60 mesh, 70 mesh, 80 mesh, 100 mesh, or 120 mesh.

[0039] The reflective heat-insulating pigments described in this application possess infrared reflection capabilities, making them suitable for heat-insulating coatings and achieving environmentally friendly and energy-saving effects. In some embodiments, the particle size of the aforementioned reflective heat-insulating pigments is 500-800 mesh, and they are one or more of reflective heat-insulating titanium dioxide, reflective heat-insulating red pigment, reflective heat-insulating yellow pigment, and reflective heat-insulating black pigment. In some embodiments, the reflective heat-insulating pigments selected in this application are distributed according to particle size. After mixing and sintering, the reflective heat-insulating pigments of different particle sizes are arranged alternately, which can better exert the reflective heat-insulating performance.

[0040] In some embodiments, the co-solvent is one or more of condensed aluminum phosphate, sodium fluorosilicate, and silicon tripolyphosphate.

[0041] In some embodiments, the water-soluble polymer in the modified acrylate emulsion is cellulose or a derivative thereof. In some embodiments, the water-soluble polymer is selected from one or more of cellulose, hydroxymethylcellulose, hydroxyethylmethylcellulose, hydroxyethylethylcellulose, and hydroxypropylmethylcellulose.

[0042] In some embodiments, the acrylic monomers in the modified acrylate emulsion are at least two of acrylic acid, methacrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, isooctyl acrylate, and methyl methacrylate.

[0043] Preferably, the initiator is one or more of ammonium persulfate, potassium persulfate, azobisisobutyronitrile, and azobiscyanopentanoic acid.

[0044] In some embodiments, the mass ratio of the water-soluble polymer to the modified silica in the modified silica sol is 1:(8~12).

[0045] In some embodiments, the content of modified silica in the modified acrylate emulsion is 5wt% to 15wt% of the total mass of the acrylic monomers.

[0046] In some embodiments, the amount of the initiator added is 0.5wt% to 5wt% of the total mass of the acrylic monomers.

[0047] In some embodiments, the polymerization reaction is carried out at a temperature of 60°C to 80°C.

[0048] In this application, the acid-base regulator is used to control the pH of the modified composite emulsion. In some embodiments, the pH of the modified composite emulsion is 6-8, and the acid-base regulator may be one or more of AMP-95, sodium hydroxide solution, and ammonia solution, but is not limited to.

[0049] The film-forming aids described in this application can improve the film-forming performance and quality of paints, enabling the formation of a continuous and uniform coating during application. This application does not limit the type of film-forming aid, but preferably uses film-forming aids with good stability, good miscibility, and environmental friendliness. These aids can be one or more of, but are not limited to, alcohol-based film-forming aids, alcohol ester-based film-forming aids, alcohol ether-based film-forming aids, and alcohol ether ester-based film-forming aids. Specifically, examples include Texanol produced by Eastman Chemical Company and alcohol ester dodecylbenzene produced by Ruentex Chemical Company.

[0050] The multifunctional additives described in this application can improve the dispersion stability of various fillers and synergistically thicken with thickeners to improve paint performance. This application does not limit the types of multifunctional additives described above. All multifunctional additives reported in the prior art for use in the coatings field are applicable to this application, such as, but not limited to, AMP-95.

[0051] This application does not specifically limit the type of defoamer mentioned above, but prefers defoamers that can defoam quickly, defoam for a long time, and have good compatibility with other components, such as mineral oil defoamers, silicone defoamers, and polyether defoamers. Specifically, such as NOPCO NXZ, Blackburn CF245, and Hemings DF7035.

[0052] In some embodiments, the above-mentioned coating additives include one or more of thickeners, bactericides, and anti-settling agents.

[0053] In some embodiments, the thickener is one or more of cellulose-based thickeners and acrylic-based thickeners.

[0054] This application does not limit the types of bactericides mentioned above. All bactericides used in the coatings field in the prior art are applicable to this application, such as, but not limited to, Sol HF, Dow QK-20, and Troy Mergal 530A.

[0055] On the other hand, this application also provides a method for preparing the above-mentioned reflective heat-insulating sand-wall paint, such as... Figure 1 As shown, it includes the following steps: S1. Modified silica sol, sodium silicate, quartz sand, reflective heat-insulating pigment and flux are mixed according to the formula and then sintered to obtain reflective heat-insulating sintered colored sand. S2. Mix the modified acrylic emulsion, acid-base regulator, film-forming aid, multifunctional aid and defoamer according to the formula to obtain the modified composite emulsion; S3. Mix the above-mentioned reflective heat-insulating sintered colored sand, the above-mentioned modified composite emulsion, coating additives and water according to the formula to obtain reflective heat-insulating sand wall paint.

[0056] This application does not limit the ratio between silica, coupling agent, and dispersant in step S1. As long as silica can be completely modified, it is within the scope of protection of this application. In some embodiments, in order to reduce the preparation difficulty and improve the dispersibility of modified silica in the modified silica sol, commercially available silica dispersions can be mixed with coupling agents and dispersants to prepare modified silica sol.

[0057] In some embodiments, in step S1, the sintering temperature is 400℃~800℃ and the sintering time is 10min~15min.

[0058] In some embodiments, in step S2, the mixing speed is 1000 rpm to 1500 rpm, and the mixing time is 10 min to 30 min.

[0059] In some embodiments, in step S3, the mixing speed is 300 rpm to 800 rpm, and the mixing time is 0.5 h to 1 h.

[0060] On the other hand, this application also provides the application of the above-mentioned reflective heat-insulating sand wall paint in the preparation of reflective heat-insulating coating, wherein the above-mentioned reflective heat-insulating sand wall paint is applied to the surface of a substrate and dried completely to obtain a reflective heat-insulating coating.

[0061] Based on this, this application provides a reflective heat-insulating coating, which is obtained by applying the above-mentioned reflective heat-insulating sand wall paint to the surface of a substrate and then drying it completely.

[0062] This application, by introducing modified silica sol and adjusting the appropriate ratio of modified silica sol to other components, can significantly improve the stability of modified composite emulsion and the pigment adhesion of reflective heat-insulating sintered colored sand, resulting in high color fastness. The synergistic effect enables the prepared reflective heat-insulating coating to have good reflective heat-insulating performance, excellent weather resistance and stain resistance, and long-lasting heat insulation effect.

[0063] It should be understood that materials of the same or similar type, model, quality, properties, or function as the reagents and instruments used in the following embodiments can be used to implement this application. Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods. Unless otherwise specified, the materials and reagents used in the following embodiments are commercially available.

[0064] The following are examples and comparative examples: Example 1 1) Preparation of modified silica sol: 200g of Grid V-820 nano silica dispersion (particle size 20nm, purchased from Shanghai Grid Chemical Co., Ltd.) was ultrasonically dispersed in 500mL of a mixture (mass ratio of deionized water and anhydrous ethanol 1:1). Then, 60g of dispersant (N-methylpyrrolidone) and 15g of coupling agent (silane coupling agent KH-550) were added. After stirring at a constant temperature of 60℃ for 1h, the mixture was evaporated and concentrated to obtain a modified silica sol with a mass percentage of 20%.

[0065] 2) Preparation of small-scale reflective heat-insulating sintered colored sand samples: The modified silica sol prepared in step (1) and sodium silicate with different moduli (2.5, 3.0, 3.5, 4.0) were mixed at a mass ratio of 1:10 to form inorganic resin samples 1-4. Then, 10g of samples 1-4, 400g of quartz white sand with a mesh size of 40-80, and 4g of reflective heat-insulating pigment (including 2g of Huntsman reflective heat-insulating pigment 550 and 2g of high-temperature resistant, ultra-weather resistant, reddish-brown, infrared-reflecting inorganic pigment brown 10P857 produced by Shepherd Company of the United States) were stirred and mixed at a speed of 500r / min using a spiral stirring plate. Then, the mixture was heated by air at 60℃ for 8min until it was evenly dispersed. Next, it was placed in a 500℃ oven and fired for 14min. Then, the mixture was discharged and cooled to obtain reflective heat-insulating sintered colored sand samples 1-4.

[0066] 100g of reflective heat-insulating sintered colored sand samples 1-4 were mixed with water at 80℃ at a mass ratio of 1:3 to obtain solutions 1#-4#. After standing for 24 hours, the mixture was stirred and the color of solutions 1#-4# was observed.

[0067] like Figure 2 As shown, solutions #1 and #4 showed obvious discoloration and turbidity after standing and stirring, while solutions #2 and #3 were clean and turbid after standing and stirring. This indicates that the color fastness of the reflective heat-insulating sintered colored sand samples 2-3 is excellent, that is, the inorganic resin prepared with a sodium silicate modulus of 3.0-3.5 has excellent bonding performance and strong adhesion.

[0068] The modified silica sol prepared in step (1) and sodium silicate with a modulus of 3.2 were mixed at mass ratios of 1:5, 1:8, 1:10, 1:12, and 1:15, respectively, to obtain inorganic resin samples 5-9. Then, 10g of sample 5-9, 400g of quartz white sand with a mesh size of 40-80, and 4g of reflective heat-insulating pigment (including 2g of Huntsman reflective heat-insulating pigment 550 and 2g of infrared reflective pigment cold pigment titanium nickel manganese black-brown powder brown 10P850 produced by Shepherd Company, USA) were stirred and mixed at a speed of 500r / min. Then, the mixture was heated and dispersed evenly by air at 60℃, and then placed in a 500℃ oven for 15min. After cooling, reflective heat-insulating sintered colored sand samples 5-9 were obtained. 100g of reflective heat-insulating sintered colored sand samples 5-9 were mixed with water at 80℃ at a mass ratio of 1:1 to obtain solutions 5#-9#. After standing for 24 hours, the mixture was stirred and the color of solutions 5#-9# was observed.

[0069] Experimental results show that solutions #5 and #9 exhibited significant color fading and turbidity after standing and stirring, while solutions #6 to #8 remained clean and turbid after standing and stirring. This indicates that the color fastness of the reflective heat-insulating sintered colored sand samples #6 to #8 is excellent, meaning that the inorganic resin prepared with a mass ratio of modified silica sol and sodium silicate of 1:(8 to 12) has excellent bonding performance and strong adhesion.

[0070] Example 2 1) Preparation of modified emulsion: The modified silica sol (20% by mass of modified SiO2) prepared in Example 1 and the aqueous solution of hydroxypropyl methylcellulose (1% by mass of HPMC) were mixed evenly. Then, acrylic monomers (including AA acrylate, butyl acrylate, HPA hydroxypropyl acrylate, and MMA methyl methacrylate) and an initiator (potassium persulfate KPS) were added, and a polymerization reaction was carried out at 70°C to obtain a modified emulsion. The stability of the modified emulsion was observed by adjusting the mass ratio of modified SiO2 to HPMC and the mass ratio of modified SiO2 to acrylic monomers in the modified emulsion.

[0071] Experiments revealed that when the mass ratio of modified SiO2 to HPMC in the modified emulsion was 5:1, the prepared modified emulsion exhibited poor stability and was prone to stratification; when the mass ratio of modified SiO2 to HPMC was 15:1, the dispersibility of modified SiO2 was poor. When the modified SiO2 content in the modified emulsion was 20% of the mass of acrylic monomers, a large amount of SiO2 remained free in the solvent and did not undergo polymerization with the acrylic monomers, resulting in significant precipitation in the prepared modified emulsion; when no modified silica sol was added, the prepared emulsion had low viscosity and poor storage stability.

[0072] 2) Preparation of modified composite emulsion: 1g / 2.5g / 4g / 5g / 7.5g / 9g of the modified silica sol prepared in Example 1 (with a modified SiO2 content of 20% by mass) were mixed with 10mL of hydroxypropyl methylcellulose aqueous solution (HPMC content of 1% by mass) and then 10g of acrylic monomers (including 1.5g of AA acrylic acid, 2.5g of butyl acrylate, 1g of hydroxypropyl acrylate, and 6g of methyl methacrylate, MMA) and 0.3g of initiator (potassium persulfate, KPS) were added, and polymerization was carried out at 70°C to obtain modified emulsions with modified SiO2 content of 2%, 5%, 8%, 10%, 15%, and 18% by mass of acrylic monomers.

[0073] 100 parts of the modified emulsion prepared above, 5 parts of film-forming aid (Texnaol), 2 parts of multifunctional aid (APM-95), and 2 parts of defoamer (NOPCO NXZ) were mixed and stirred at 1000 rpm for 30 min to obtain a modified composite emulsion. Then, the modified composite emulsion and the sintered colored sand sample 7 prepared in Example 1 were used to make a sample paint. A composite coating was then obtained through experimental plate making, and the ultraviolet light absorptivity, ultraviolet (UV) reflectance, visible light (VIS) reflectance, and near-infrared (NIR) reflectance of the composite coating at 270 nm in the ultraviolet band were tested. The results are shown in Table 1.

[0074] Table 1. Average values ​​of UV absorptivity and reflectivity of the composite coating

[0075] As shown in Table 1, adding modified silica sol to the composite coating can improve the absorption ratio of the coating in the ultraviolet light band. The reason for this is likely that the modified nano-SiO2 particles in the modified silica sol are uniformly dispersed in the emulsion, increasing the specific surface area for ultraviolet light absorption after film formation. Simultaneously, the modified nano-SiO2 particles have numerous organic segments and polar groups such as silanol groups on their surface, thereby enhancing the composite coating's ability to absorb ultraviolet light.

[0076] When the modified SiO2 content is 2% to 18% of the acrylic monomer mass, the NIR reflectance of the composite coating is greater than 0.62 and the VIS reflectance is greater than 0.64, indicating superior heat insulation and energy-saving performance. However, compared to a modified SiO2 content of 15% of the acrylic monomer mass, a slight decrease in NIR and VIS reflectance occurs when the modified SiO2 content is 18% of the acrylic monomer mass. This may be due to the aggregation of modified nano-SiO2 particles in the composite coating; the larger size and greater quantity of these particles lead to a decrease in visible light reflectivity.

[0077] Example 3 The components and their mass fractions of the reflective heat-insulating sand wall paint provided in this embodiment are shown in Table 2: Table 2. Components and mass fractions of reflective heat-insulating sand-textured paint

[0078] The method for preparing reflective heat-insulating sand-wall paint provided in this embodiment includes the following steps: S1. Preparation of modified silica sol: 200g of mesh V-820 nano silica dispersion (particle size 20~30nm, purchased from Shanghai Mesh Company) was ultrasonically dispersed in 500mL of a mixture (mass ratio of deionized water and anhydrous ethanol 1:1). Then, 60g of dispersant (N-methylpyrrolidone) and 15g of coupling agent (silane coupling agent KH-550) were added. After stirring at a constant temperature of 60℃ for 4h, the mixture was evaporated and concentrated to obtain a modified silica sol with a mass percentage of 20%.

[0079] S2. Preparation of reflective heat-insulating sintered colored sand: The modified silica sol prepared in step S1, sodium silicate, quartz white sand, reflective heat-insulating pigment, and co-solvent are mixed evenly by stirring at 500 rpm for 0.3 h. Then, the mixture is evenly dispersed by air heat treatment at 60°C. Next, it is placed in an oven at 800°C and fired for 10 min. After cooling, reflective heat-insulating sintered colored sand is obtained.

[0080] S3. Preparation of modified emulsion: 5g of the modified silica sol prepared in step S1 (with a modified SiO2 content of 20% by mass) and 10mL of hydroxypropyl methylcellulose aqueous solution (HPMC content of 1% by mass) were mixed evenly. Then, 10g of acrylic monomers (including 1.5g of AA acrylic acid, 2.5g of butyl acrylate BA, 1g of hydroxypropyl acrylate HPA, and 6g of methyl methacrylate MMA) and 0.2g of initiator (potassium persulfate KPS) were added, and the polymerization reaction was carried out at 60℃ to obtain the modified emulsion.

[0081] S4. Preparation of modified composite emulsion: The modified emulsion prepared in step S3, along with the acid-base regulator, film-forming aid, multifunctional aid, and defoamer, were stirred at 1000 rpm for 30 minutes until homogeneous, resulting in a modified composite emulsion.

[0082] S5. Preparation of reflective heat-insulating sand-wall paint: The reflective heat-insulating sintered colored sand prepared in step S2, the modified composite emulsion prepared in step S4, and the above thickener and bactericide are stirred at 300 rpm for 1 hour to prepare the paint, thus obtaining the reflective heat-insulating sand wall paint.

[0083] Example 4 The components and their mass fractions of the reflective heat-insulating sand wall paint provided in this embodiment are shown in Table 3: Table 3. Components and mass fractions of reflective heat-insulating sand-textured paint

[0084] The method for preparing reflective heat-insulating sand-wall paint provided in this embodiment includes the following steps: S1. Preparation of modified silica sol: 100g of Aurun 308 nano silica dispersion (particle size 50nm, purchased from Shanghai Aurun Chemical Co., Ltd.) was ultrasonically dispersed in 200mL of a mixture (mass ratio of deionized water and anhydrous ethanol 1:1). Then, 20g of dispersant (N-methylpyrrolidone) and 5g of coupling agent (silane coupling agent KH-550) were added. After stirring at a constant temperature of 60℃ for 4h, the mixture was evaporated and concentrated to obtain a modified silica sol with a mass percentage of 25%.

[0085] S2. Preparation of reflective heat-insulating sintered colored sand: The modified silica sol prepared in step S1, sodium silicate, quartz white sand, reflective heat-insulating pigment, and co-solvent are mixed evenly by stirring at 500 rpm for 0.3 h. Then, the mixture is evenly dispersed by air heat treatment at 60°C. Next, it is placed in an oven at 500°C and fired for 12 min. After cooling, reflective heat-insulating sintered colored sand is obtained.

[0086] S3. Preparation of modified emulsion: 3.2g of the modified silica sol prepared in step S1 (with a modified SiO2 content of 25% by mass) and 10mL of hydroxypropyl methylcellulose aqueous solution (HPMC content of 1% by mass) were mixed evenly. Then, 10g of acrylic monomers (including 1.5g of AA acrylate, 2.5g of butyl acrylate BA, 1g of hydroxypropyl acrylate HPA, and 6g of methyl methacrylate MMA) and 0.5g of initiator (potassium persulfate KPS) were added, and the polymerization reaction was carried out at 70℃ to obtain the modified emulsion.

[0087] S4. Preparation of modified composite emulsion: The modified emulsion, acid-base regulator, film-forming aid, multifunctional aid, and defoamer prepared in step S3 were stirred at 1200 rpm for 20 min and mixed evenly to obtain the modified composite emulsion.

[0088] S5. Preparation of reflective heat-insulating sand-wall paint: Following the method provided in Example 3, the reflective heat-insulating sintered colored sand prepared in step S2, the modified composite emulsion prepared in step S4, and the above-mentioned thickener and bactericide are stirred at 500 rpm for 50 min to obtain reflective heat-insulating sand wall paint.

[0089] Example 5 The components and their mass fractions of the reflective heat-insulating sand wall paint provided in this embodiment are shown in Table 4: Table 4. Components and mass fractions of reflective heat-insulating sand-textured paint

[0090] The method for preparing reflective heat-insulating sand-wall paint provided in this embodiment includes the following steps: S1. Preparation of modified silica sol: 150g of CH83-123 nano silica dispersion (particle size 8~10nm, purchased from Jiangsu Guolian Technology Co., Ltd.) from Jiangsu Guolian was ultrasonically dispersed in 500mL of a mixed solution (mass ratio of deionized water and anhydrous ethanol 1:1). Then, 40g of dispersant (N-methylpyrrolidone) and 10g of coupling agent (silane coupling agent KH-550) were added. After stirring at a constant temperature of 60℃ for 4h, the mixture was evaporated and concentrated to obtain a modified silica sol with a mass percentage of 30%.

[0091] S2. Preparation of reflective heat-insulating sintered colored sand: The modified silica sol prepared in step S1, sodium silicate, quartz white sand, reflective heat-insulating pigment, and co-solvent are stirred at 500 rpm for 0.3 h to mix evenly. Then, the mixture is heat-dispersed evenly by air treatment at 60°C. Next, it is placed in an oven at 400°C and fired for 15 min. After cooling, reflective heat-insulating sintered colored sand is obtained.

[0092] S3. Preparation of modified emulsion: 4g of the modified silica sol prepared in step S1 (with a modified SiO2 content of 30% by mass) and 10mL of hydroxypropyl methylcellulose aqueous solution (HPMC content of 1% by mass) were mixed evenly. Then, 10g of acrylic monomers (including 1.5g of AA acrylate, 2.5g of butyl acrylate BA, 1g of hydroxypropyl acrylate HPA, and 6g of methyl methacrylate MMA) and 0.2g of initiator (potassium persulfate KPS) were added, and the polymerization reaction was carried out at 80℃ to obtain the modified emulsion.

[0093] S4. Preparation of modified composite emulsion: The modified emulsion prepared in step S3, acid-base regulator, film-forming aid, multifunctional aid, and defoamer were stirred at 1500 rpm for 10 min and mixed evenly to obtain the modified composite emulsion.

[0094] S5. Preparation of reflective heat-insulating sand-wall paint: Following the method provided in Example 3, the reflective heat-insulating sintered colored sand prepared in step S2, the modified composite emulsion prepared in step S4, and the above-mentioned thickener and bactericide were stirred at 800 rpm for 0.5 h to obtain reflective heat-insulating sand wall paint.

[0095] Comparative Example 1 In the preparation method of the reflective heat-insulating sand wall paint provided in this comparative example, no modified silica sol was added when preparing the modified emulsion in step S3. The other steps are the same as in Example 4, and the reflective heat-insulating sand wall paint is prepared.

[0096] Comparative Example 2 In the preparation method of the reflective heat-insulating sand wall paint provided in this comparative example, no modified silica sol was added when preparing reflective heat-insulating sintered colored sand in step S2. The other steps are the same as in Example 4, and the reflective heat-insulating sand wall paint is prepared.

[0097] Exterior wall coatings with sand-like finishes are mainly water-based thick-film imitation stone paints, including real stone paint, textured paint, and water-based sand-containing paints. They are characterized by a hard film, high realism in imitation stone, strong impact resistance, and a thick coating, and also have a certain ability to cover minor cracks in the substrate. In addition to the above properties, reflective heat-insulating sand-like coatings can also give buildings the ability to reflect sunlight, reducing building energy consumption and thus contributing to continuous energy conservation and carbon reduction in buildings. The performance of the reflective heat-insulating sand-like coatings prepared in Examples 3-5 and Comparative Examples 1-2 was tested according to the testing methods in the industry standard JG / T 235-2014 "Architectural Reflective Heat-Insulating Coatings". The test results are shown in Table 5.

[0098] Table 5 Performance of Reflective Heat Insulation Sandpaper

[0099] The results show that by introducing modified silica sol into the composite emulsion and reflective heat-insulating sintered colored sand and adjusting the ratio of modified silica sol to other components, this application can significantly improve the stability of the modified composite emulsion, as well as the color stability and pigment adhesion of the reflective heat-insulating sintered colored sand. By compounding the reflective heat-insulating sintered colored sand, modified composite emulsion, and coating additives, the synergistic effect results in a coating on the building surface that exhibits high ultraviolet light absorption ratio and near-infrared reflectance ratio, good reflective heat insulation performance, excellent weather resistance and stain resistance, and durable reflective heat insulation effect.

[0100] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A reflective heat-insulating sand-textured paint, characterized in that, It includes the following components and their mass fractions: 650-750 parts reflective heat-insulating sintered colored sand, 120-160 parts modified composite emulsion, 5-15 parts coating additives and 100-150 parts water; The reflective heat-insulating sintered colored sand comprises modified silica sol, sodium silicate, quartz sand, reflective heat-insulating pigment, and a co-solvent, wherein the mass ratio of modified silica sol, sodium silicate, quartz sand, reflective heat-insulating pigment, and co-solvent is 1:(8~12):(500~800):(3~7):(0.5~1); the modified silica sol is obtained by heating and mixing nano-silica, coupling agent, and dispersant, followed by concentration, wherein the mass percentage of modified silica in the modified silica sol is 20%~30%; The modified composite emulsion includes a modified acrylic emulsion, an acid-base regulator, a film-forming aid, a multifunctional aid, and an antifoaming agent, and the mass ratio of the modified acrylic emulsion, the acid-base regulator, the film-forming aid, the multifunctional aid, and the antifoaming agent is 100:(2~4):(3~5):(1~2):(1~2). The modified acrylate emulsion is prepared by polymerization reaction of acrylic monomers, water-soluble polymers and the modified silica sol, under the action of an initiator.

2. The reflective heat-insulating sand-wall paint according to claim 1, characterized in that, The particle size of the nano-silica is 5nm~60nm; The coupling agent is a silane coupling agent, selected from one or more of silane coupling agents KH-550, KH-560, and KH-570; The dispersant is one or more of N-methylpyrrolidone, α-pyrrolidone, and N-vinylpyrrolidone.

3. The reflective heat-insulating sand-wall paint according to claim 1, characterized in that, The modulus of the sodium silicate is 3.0 to 3.

5.

4. The reflective heat-insulating sand-wall paint according to claim 1, characterized in that, The water-soluble polymer is cellulose or a derivative thereof, and the water-soluble polymer is selected from one or more of cellulose, hydroxymethylcellulose, hydroxyethylmethylcellulose, hydroxyethylethylcellulose, and hydroxypropylmethylcellulose. The acrylic monomer is at least two of the following: acrylic acid, methacrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, isooctyl acrylate, and methyl methacrylate. The initiator is one or more of ammonium persulfate, potassium persulfate, azobisisobutyronitrile, and azobiscyanopentanoic acid.

5. The reflective heat-insulating sand-wall paint according to claim 4, characterized in that, In the modified acrylate emulsion, the mass ratio of the water-soluble polymer to the modified silica in the modified silica sol is 1:(8~12). The modified silica content in the modified acrylate emulsion is 5wt% to 15wt% of the total mass of the acrylic monomers.

6. The reflective heat-insulating sand-wall paint according to claim 1, characterized in that, The quartz sand has a mesh size of 40-120; and / or, The reflective heat-insulating pigment is one or more of the following: reflective heat-insulating titanium dioxide, reflective heat-insulating red pigment, reflective heat-insulating yellow pigment, and reflective heat-insulating black pigment; and / or, The co-solvent is one or more of condensed aluminum phosphate, sodium fluorosilicate, and silicon tripolyphosphate; and / or The acid-base regulator is one or more of sodium hydroxide solution, ammonia solution, and AMP-95; and / or, The film-forming aid is one or more of the following: alcohol-based film-forming aids, alcohol ester-based film-forming aids, alcohol ether-based film-forming aids, and alcohol ether ester-based film-forming aids; and / or, The defoamer is one or more of the following: mineral oil defoamer, silicone defoamer, and polyether defoamer.

7. The reflective heat-insulating sand-wall paint according to claim 1, characterized in that, The coating additives include one or more of thickeners, bactericides, and anti-settling agents.

8. A method for preparing a reflective heat-insulating sand-wall paint according to any one of claims 1 to 7, characterized in that, Includes the following steps: S1. The modified silica sol, sodium silicate, quartz sand, reflective heat-insulating pigment and flux are mixed according to the formula and then sintered to obtain reflective heat-insulating sintered colored sand. S2. Mix the modified acrylic emulsion, acid-base regulator, film-forming aid, multifunctional aid and defoamer according to the formula to obtain the modified composite emulsion; S3. Mix the reflective heat-insulating sintered colored sand, the modified composite emulsion, the coating additives and water according to the formula to obtain reflective heat-insulating sand wall paint.

9. A reflective heat-insulating coating, characterized in that, It is obtained by coating the substrate surface with the reflective heat-insulating sand wall paint as described in any one of claims 1 to 7 and then drying it completely.

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