Reflective heat-insulation sand wall paint as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of building coatings, and particularly relates to reflective heat-insulation sand wall paint as well as a preparation method and application thereof. According to the reflective heat-insulation sand wall paint provided by the invention, the modified silica sol is introduced into the composite emulsion and the reflective heat-insulation sintered color sand, and the ratio of the modified silica sol to other components is regulated and controlled, so that the stability of the modified composite emulsion and the color stability and pigment adhesion of the reflective heat-insulation sintered color sand can be obviously improved. Through the synergistic effect of the components, a coating formed by coating the reflective heat-insulation sand wall paint on the surface of a building has high ultraviolet light absorption ratio and near-infrared reflectance ratio, good reflective heat-insulation performance, excellent weather resistance and stain resistance and more durable reflective heat-insulation effect.

Description

Technical Field

[0001] The present application belongs to the technical field of architectural coatings, and more specifically, relates to a reflective heat-insulating sand wall paint, a preparation method thereof, and an application thereof. Background Art

[0002] At present, 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 use function of buildings. Reflective thermal insulation coatings for buildings can reduce the absorption of solar radiation energy by the building surface by effectively reflecting the solar heat radiation in summer. After the exterior wall of the building is painted with such coatings, the surface temperature of the coating film will not increase significantly, thereby reducing the heat transferred into the building through the wall. At present, most of the reflective thermal insulation coatings for buildings are acrylic resin emulsion coatings, which have poor stain resistance. With the extension of the use time of the coating surface, the heat reflection effect of the coating is seriously reduced. In some cities with serious air pollution, the heat reflection effect of the coating will be reduced by 50% in less than 2 years, and the aging resistance is poor. Therefore, in addition to having 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 thermal insulation effect of the coating. Summary of the invention

[0003] In view of the defects of the prior art, the purpose of this application is to provide a reflective thermal insulation sand wall paint, its preparation method and application, aiming to solve the problems of poor storage stability, stain resistance and aging resistance of existing reflective thermal insulation coatings, and low durability of the coating's thermal insulation effect.

[0004] To achieve the above objectives, in a first aspect, the present application provides a reflective heat-insulating sand wall paint, which includes the following components and their mass fractions: 650~750 parts of reflective heat-insulating sintered colored sand, 120~160 parts of modified composite emulsion, 5~15 parts of coating additives and 100~150 parts of water; The reflective heat-insulating sintered colored sand comprises modified silica sol, sodium silicate, quartz sand, reflective heat-insulating pigment and co-solvent, and the mass ratio of the 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 composite emulsion comprises a modified acrylic emulsion, an acid-base regulator, a film-forming aid, a multifunctional aid and a defoaming agent, and the mass ratio of the modified acrylic emulsion, the acid-base regulator, the film-forming aid, the multifunctional aid and the defoaming agent is 100:(2-4):(3-5):(1-2):(1-2); The modified acrylic ester emulsion is prepared by using acrylic monomers as raw materials, adding water-soluble polymers and the modified silica sol, and performing polymerization reaction under the action of an initiator.

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

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

[0007] Preferably, the particle size of the nano-silicon dioxide 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 3.0-3.5.

[0011] Preferably, the water-soluble polymer is cellulose or a derivative thereof. Further preferably, the water-soluble polymer is selected from one or more of cellulose, hydroxymethyl cellulose, hydroxyethyl methyl cellulose, hydroxyethyl ethyl cellulose, and hydroxypropyl methyl cellulose.

[0012] Preferably, the acrylic monomers 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 azobiscyanovaleric acid.

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

[0015] Preferably, the content of modified silicon dioxide in the modified acrylic ester emulsion is 5wt% to 15wt% of the total mass of the acrylic monomer.

[0016] Preferably, the added amount of the above-mentioned initiator is 0.5wt%~5wt% of the total mass of the acrylic monomer.

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

[0018] Preferably, the above-mentioned 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 above-mentioned 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 above-mentioned film-forming aid is one or more of an alcohol film-forming aid, an alcohol ester film-forming aid, an alcohol ether film-forming aid, and an alcohol ether ester film-forming aid.

[0022] Preferably, the defoaming agent is one or more of a mineral oil defoaming agent, a silicone defoaming agent, and a polyether defoaming agent.

[0023] Preferably, the coating additives include one or more of a thickener, a bactericide, and an anti-settling agent.

[0024] In a second aspect, the present application provides a method for preparing the above-mentioned reflective heat-insulating sand wall paint, comprising the following steps: S1, mixing the modified silica sol, sodium silicate, quartz sand, reflective heat-insulating pigment and co-solvent according to a ratio and sintering to obtain reflective heat-insulating sintered colored sand; S2, mixing the modified acrylic emulsion, acid-base regulator, film-forming aid, multifunctional aid and defoamer according to a ratio to obtain a modified composite emulsion; S3, mixing the above-mentioned reflective heat-insulating sintered colored sand, the above-mentioned modified composite emulsion, coating additives and water according to a proportion to obtain reflective heat-insulating sand wall paint.

[0025] In a third aspect, the present application provides a reflective heat-insulating coating, which is obtained by coating the above-mentioned reflective heat-insulating sand wall paint on the surface of a substrate and completely drying it.

[0026] In general, the above technical solutions conceived by this application have the following technical advantages compared with the prior art: The reflective heat-insulating sand wall paint provided by the present application can significantly improve 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 regulating the ratio of the modified silica sol to other components. At the same time, the modified silica sol has good dispersibility in the composite emulsion, and can increase the microscopic surface roughness of the composite emulsion after film formation, thereby improving the hydrophilic effect of the coating and improving the stain resistance during outdoor application. In addition, the color stability of the prepared reflective heat-insulating sintered colored sand is better, the pigment adhesion is stronger, and the reflective heat-insulating performance of the reflective heat-insulating sintered colored sand is improved. By compounding the reflective heat-insulating sintered colored sand, the modified composite emulsion and the coating additive, the prepared reflective heat-insulating sand wall paint is applied to the surface of the building to form a coating with a high ultraviolet absorption ratio and a near-infrared reflectance ratio, and the reflective heat-insulating performance is excellent. The gradation combination of the above-mentioned reflective heat-insulating sintered colored sand makes the coating surface flat and dense, with few pores, and it is difficult for fine dust particles to invade its pores, and it has excellent stain resistance and weather resistance, and the reflective heat-insulating effect is durable. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic flow chart of a method for preparing a reflective heat-insulating sand wall paint provided in an embodiment of the present application; Figure 2 It is the color fastness of the reflective insulation sintered colored sand sample prepared in the embodiment of the present application. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0029] In the description of this application, it should be understood that the term "and / or" is a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. The symbol " / " herein indicates that the associated objects are in an or relationship, for example, A / B means A or B.

[0030] The present application provides a reflective heat-insulating sand wall paint, which includes the following components and their mass fractions: 650~750 parts of reflective heat-insulating sintered colored sand, 120~160 parts of modified composite emulsion and 5~15 parts of coating additives; The reflective heat-insulating sintered colored sand comprises modified silica sol, sodium silicate, quartz sand, reflective heat-insulating pigment and co-solvent, and the mass ratio of the 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 composite emulsion comprises a modified acrylic emulsion, an acid-base regulator, a film-forming aid, a multifunctional aid and a defoaming agent, and the mass ratio of the modified acrylic emulsion, the acid-base regulator, the film-forming aid, the multifunctional aid and the defoaming agent is 100:(2-4):(3-5):(1-2):(1-2); The modified acrylic ester emulsion is prepared by using acrylic monomers as raw materials, adding water-soluble polymers and the modified silica sol, and performing polymerization reaction under the action of an initiator.

[0031] In some embodiments, the mass percentage of modified silicon dioxide in the modified silica sol is 20% to 30%.

[0032] The present application does not limit the preparation method of the modified silica sol, for example, but not limited to, heating and mixing nano-silica, coupling agent and dispersant and then concentrating the obtained sol. The present 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 protection scope of the present application.

[0033] In some embodiments, the particle size of the nano-silicon dioxide is 5-60 nm, preferably 10-50 nm.

[0034] In some embodiments, in order to reduce the difficulty of preparation and improve the dispersibility of silica in the modified silica sol, a commercially available nano-silica dispersion can be selected and mixed with a coupling agent and a dispersant to prepare the modified silica sol. In some embodiments, the above-mentioned silica dispersion can be but is not limited to Grid V-820 nano-silica dispersion, Aorun 308 nano-silica dispersion, and CH83-123 nano-silica dispersion.

[0035] In some embodiments, the coupling agent is a silane coupling agent, selected from one or more of 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, 3.5. The inventors of the present application have found through experiments that the inorganic resin prepared by combining the modified silica sol and components such as sodium silicate with a suitable modulus, quartz sand, reflective heat-insulating pigments and cosolvents has excellent bonding properties and strong adhesion.

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

[0039] In the present application, the above-mentioned reflective heat-insulating pigment has an infrared reflection function, is suitable for heat-insulating coatings, and achieves environmental protection and energy-saving effects. In some embodiments, the particle size of the above-mentioned reflective heat-insulating pigment is 500~800 mesh, and 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. In some embodiments, the reflective heat-insulating pigment selected in the present application is distributed according to the particle size, and after mixing and sintering, the reflective heat-insulating pigments of different particle sizes are staggered, which can better exert the reflective heat-insulating performance.

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

[0041] In some embodiments, in the modified acrylic emulsion, the water-soluble polymer is cellulose or its derivatives. In some embodiments, the water-soluble polymer is selected from one or more of cellulose, hydroxymethyl cellulose, hydroxyethyl methyl cellulose, hydroxyethyl ethyl cellulose, and hydroxypropyl methyl cellulose.

[0042] In some embodiments, in the modified acrylic ester emulsion, the acrylic monomers 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 azobiscyanovaleric acid.

[0044] In some embodiments, in the modified acrylic ester emulsion, 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 silicon dioxide in the modified acrylic ester emulsion is 5 wt % to 15 wt % of the total mass of the acrylic monomer.

[0046] In some embodiments, the added amount of the above-mentioned initiator is 0.5wt%~5wt% of the total mass of the above-mentioned acrylic monomer.

[0047] In some embodiments, the polymerization reaction temperature is 60°C to 80°C.

[0048] In the present application, the acid-base regulator is used to adjust 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 can be, but is not limited to, one or more of AMP-95, sodium hydroxide solution, and ammonia solution.

[0049] In the present application, the above-mentioned film-forming aid can improve the film-forming performance and quality of the paint, and can form a continuous and uniform coating film during coating. The present application does not limit the type of the above-mentioned film-forming aid, and preferably has good stability, good miscibility, and is environmentally friendly. It can be, but is not limited to, one or more of alcohol film-forming aids, alcohol ester film-forming aids, alcohol ether film-forming aids, and alcohol ether ester film-forming aids. Specifically, such as Texanol produced by Eastman Company and alcohol ester twelve produced by Runtai Chemical Company.

[0050] The multifunctional additives mentioned above in the present application can improve the dispersion stability of various fillers, and cooperate with the thickener to play a thickening role and improve the performance of the paint. The present application does not limit the types of the multifunctional additives mentioned above. The multifunctional additives used in the coating field reported in the prior art are all suitable for the present application, such as but not limited to AMP-95.

[0051] The present application does not specifically limit the types of the above defoaming agents, and preferably the defoaming agents that can quickly and persistently defoam and have good compatibility with other components, such as mineral oil defoaming agents, silicone defoaming agents, and polyether defoaming agents. Specifically, such as NOPCO NXZ, Blackburn CF245, and Hemmings DF7035.

[0052] In some embodiments, the coating additives include one or more of a thickener, a bactericide, and an anti-settling agent.

[0053] In some embodiments, the thickener is one or more of a cellulose thickener and an acrylic thickener.

[0054] The present application does not limit the types of the above-mentioned fungicides, and all fungicides used in the coating field in the prior art are suitable for the present application, such as but not limited to Sol HF, Dow QK-20, and Troy Mergal 530A.

[0055] On the other hand, the present application also provides a method for preparing the above-mentioned reflective heat-insulating sand wall paint, such as Figure 1 As shown, the following steps are included: S1. Mixing modified silica sol, sodium silicate, quartz sand, reflective heat-insulating pigment and co-solvent according to a proportion and sintering the mixture to obtain reflective heat-insulating sintered colored sand; S2, mixing the modified acrylic ester emulsion, the acid-base regulator, the film-forming aid, the multifunctional aid and the defoaming agent according to a ratio to obtain a modified composite emulsion; S3, mixing the above-mentioned reflective heat-insulating sintered colored sand, the above-mentioned modified composite emulsion, coating additives and water according to a proportion to obtain reflective heat-insulating sand wall paint.

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

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

[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, the present application also provides the use of the above-mentioned reflective thermal insulation sand wall paint in the preparation of a reflective thermal insulation coating, and the above-mentioned reflective thermal insulation sand wall paint is applied to the surface of a substrate until it is completely dried to obtain a reflective thermal insulation coating.

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

[0062] By introducing modified silica sol and adjusting the appropriate ratio of modified silica sol to other components, the present application can significantly improve the stability of the modified composite emulsion, as well as the pigment adhesion of the reflective thermal insulation sintered colored sand, and the high color fastness. The synergistic effect makes the prepared reflective thermal insulation coating have good reflective thermal insulation performance, excellent weather resistance and stain resistance, and the thermal insulation effect is long-lasting and durable.

[0063] It should be understood that materials of the same or similar type, model, quality, nature or function as the reagents and instruments used in the following examples can be used to implement the present application. The experimental methods used in the following examples are conventional methods unless otherwise specified. The materials, reagents, etc. used in the following examples can be obtained from commercial sources unless otherwise specified.

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

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

[0066] Respectively mix 100g of reflective insulating sintered colored sand samples 1~4 and 80℃ water in a mass ratio of 1:3 to obtain 1#~4# solutions, then stir after standing for 24 hours, and observe the color of 1#~4# solutions.

[0067] like Figure 2 As shown, 1# and 4# solutions showed obvious discoloration and turbidity after standing and stirring, while 2# and 3# solutions were clean and not turbid after standing and stirring, indicating that the color fastness of reflective insulation sintered colored sand samples 2~3 is excellent, that is, the inorganic resin made with a sodium silicate modulus of 3.0~3.5 has excellent bonding properties and strong adhesion.

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

[0069] The experimental results show that 5# solution and 9# solution showed obvious discoloration and turbidity after standing and stirring, while 6#~8# solutions were clean and not turbid after standing and stirring. This shows that the color fastness of reflective insulation sintered colored sand samples 6~8 is excellent, that is, the inorganic resin prepared by the mass ratio of modified silica sol and sodium silicate of 1:(8~12) has excellent bonding properties and strong adhesion.

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

[0071] The experiment found that when the mass ratio of modified SiO2 to HPMC in the modified emulsion was 5:1, the stability of the prepared modified emulsion was poor and easy to stratify; when the mass ratio of modified SiO2 to HPMC was 15:1, the dispersibility of modified SiO2 was poor. When the content of modified SiO2 in the modified emulsion was 20% of the mass of acrylic monomer, it was found that a large amount of SiO2 was free in the solvent and did not undergo polymerization reaction with acrylic monomer, and the prepared modified emulsion showed more precipitation; when modified silica sol was not added to the modified emulsion, the viscosity of the prepared emulsion was low and the storage stability was poor.

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

[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 defoaming agent (NOPCO NXZ) were mixed and stirred at 1000 rpm for 30 minutes to obtain a modified composite emulsion. Then the modified composite emulsion and the sintered colored sand sample 7 prepared in Example 1 were made into a sample paint, and then a composite coating was obtained by experimental plate making, and the ultraviolet light absorption ratio, ultraviolet (UV) reflectance ratio, visible light (VIS) reflectance ratio, and near infrared (NIR) reflectance ratio of the composite coating at 270 nm in the ultraviolet band were tested, and the results are shown in Table 1.

[0074] Table 1 Average values ​​of UV absorption and reflectance of composite coatings

[0075] As can be seen from Table 1, adding modified silica sol to the composite coating can improve the absorption ratio of the coating in the ultraviolet band. The reason may be that the modified nano-SiO2 particles in the modified silica sol are evenly dispersed in the emulsion. After film formation, the specific surface area of ​​the composite coating that absorbs ultraviolet light is increased. At the same time, the surface of the modified nano-SiO2 particles has more organic segments and polar groups such as silanol groups, thereby enhancing the ability of the composite coating to absorb ultraviolet light.

[0076] When the content of modified SiO2 is 2% to 18% of the mass of acrylic monomer, the NIR reflectance of the composite coating is greater than 0.62, and the VIS reflectance is greater than 0.64, and the thermal insulation and energy-saving effect of the composite coating is better. Among them, compared with the modified SiO2 content of 15% of the mass of acrylic monomer, when the modified SiO2 content is 18% of the mass of acrylic monomer, the NIR reflectance and VIS reflectance are slightly reduced. The reason for this may be that the modified nano-SiO2 particles in the composite coating are agglomerated, the modified nano-SiO2 particles are too large in size, and the number is too large, resulting in a decrease in the reflection performance of visible light.

[0077] Example 3 The components and 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 wall paint

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

[0079] S2. Preparation of reflective heat-insulating sintered colored sand: The modified silica sol prepared in step S1 and the sodium silicate, quartz white sand, reflective heat-insulating pigment and co-solvent are placed at 500 rpm and stirred for 0.3 h to be evenly mixed, then subjected to 60°C wind-cooled heating and uniform dispersion, then placed in an oven at 800°C and fired for 10 min, and cooled to obtain reflective heat-insulating sintered colored sand.

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

[0081] S4. Preparation of modified composite emulsion: The modified emulsion prepared in step S3 and the acid-base regulator, film-forming aid, multifunctional aid, and defoaming agent were stirred at 1000 rpm for 30 minutes and mixed evenly to obtain 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-mentioned thickener and bactericide are stirred at 300 rpm for 1 hour to prepare the paint, so as to obtain reflective heat-insulating sand wall paint.

[0083] Example 4 The components and 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 wall paint

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

[0085] S2. Preparation of reflective heat-insulating sintered colored sand: The modified silica sol prepared in step S1 and the sodium silicate, quartz white sand, reflective heat-insulating pigment and co-solvent are placed at 500 rpm and stirred for 0.3 h to mix evenly, then heat-dispersed evenly at 60°C by air preheating, then placed in a 500°C oven and fired for 12 minutes, and cooled to obtain reflective heat-insulating sintered colored sand.

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

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

[0088] S5. Preparation of reflective heat-insulating sand wall paint: According to the method provided in Example 3, the reflective 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 500 rpm for 50 minutes to obtain reflective insulating sand wall paint.

[0089] Example 5 The components and 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 wall paint

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

[0091] S2. Preparation of reflective heat-insulating sintered colored sand: The modified silica sol prepared in step S1 and the sodium silicate, quartz white sand, reflective insulation pigment and co-solvent are stirred at 500 rpm for 0.3 h to be evenly mixed, then subjected to 60°C wind-cooled heating and uniform dispersion, then placed in a 400°C oven for 15 min, and cooled to obtain reflective insulation sintered colored sand.

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

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

[0094] S5. Preparation of reflective heat-insulating sand wall paint: According to the method provided in Example 3, the reflective 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 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 is added when preparing the modified latex in step S3, and the other steps are the same as those in Example 4 to prepare the reflective heat-insulating sand wall paint.

[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 is added when preparing the reflective heat-insulating sintered colored sand in step S2, and the other steps are the same as those in Example 4 to prepare the reflective heat-insulating sand wall paint.

[0097] The sand wall paint for exterior wall construction is mainly composed of real stone paint, texture paint, and water-based thick stone-like paint containing sand in water. It has the characteristics of hard paint film, high stone-like fidelity, strong impact resistance, thick coating, and a certain ability to cover small cracks in the substrate. In addition to the above-mentioned properties, the reflective heat-insulating sand wall paint can also give the building the ability to reflect sunlight, reduce the energy consumption of the building, and continuously save energy and reduce carbon emissions for the building through the exterior wall reflective heat-insulating sand wall paint. According to the detection method in the industry standard JG / T 235-2014 "Architectural Reflective Heat-Insulating Coatings", the performance of the reflective heat-insulating sand wall paint prepared in Examples 3 to 5 and Comparative Examples 1 to 2 was tested, and the test results are shown in Table 5.

[0098] Table 5 Performance of reflective heat-insulating sand wall paint

[0099] The results show that the present 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 introducing modified silica sol into the composite emulsion and reflective heat-insulating sintered colored sand and adjusting the ratio of the modified silica sol to other components. By compounding the reflective heat-insulating sintered colored sand, the modified composite emulsion and the coating additive, the coating formed by the reflective heat-insulating sand wall paint applied to the surface of the building has a high ultraviolet light absorption ratio and near-infrared reflectance ratio, good reflective heat-insulating performance, excellent weather resistance and stain resistance, and a long-lasting and durable reflective heat-insulating effect.

[0100] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A reflective heat-insulating sand wall paint, characterized in that: It includes the following components and their mass fractions: 650~750 parts of reflective heat-insulating sintered colored sand, 120~160 parts of modified composite emulsion, 5~15 parts of coating additives and 100~150 parts of water; The reflective heat-insulating sintered colored sand comprises modified silica sol, sodium silicate, quartz sand, reflective heat-insulating pigment and co-solvent, and the mass ratio of the 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 composite emulsion comprises a modified acrylic emulsion, an acid-base regulator, a film-forming aid, a multifunctional aid and a defoaming agent, and the mass ratio of the modified acrylic emulsion, the acid-base regulator, the film-forming aid, the multifunctional aid and the defoaming agent is 100:(2-4):(3-5):(1-2):(1-2); The modified acrylic ester emulsion is prepared by taking acrylic monomer as raw material, adding water-soluble polymer and the modified silica sol, and carrying out polymerization reaction under the action of an initiator.

2. The reflective heat-insulating sand wall paint according to claim 1, characterized in that: The mass percentage of modified silicon dioxide in the modified silica sol is 20% to 30%.

3. The reflective heat-insulating sand wall paint according to claim 2, characterized in that: The modified silica sol is obtained by heating and mixing nano silicon dioxide, a coupling agent and a dispersant and then concentrating; Optionally, the particle size of the nano-silicon dioxide 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.

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

5.

5. 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, hydroxymethyl cellulose, hydroxyethyl methyl cellulose, hydroxyethyl ethyl cellulose, and hydroxypropyl methyl cellulose; The acrylic monomers are at least two of 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 azobiscyanovaleric acid.

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

7. The reflective heat-insulating sand wall paint according to claim 1, characterized in that: The mesh number of the quartz sand is 40 to 120 meshes; and / or, The 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; and / or, The co-solvent is one or more of condensed aluminum phosphate, sodium fluorosilicate, 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 an alcohol film-forming aid, an alcohol ester film-forming aid, an alcohol ether film-forming aid, and an alcohol ether ester film-forming aid; and / or, The defoaming agent is one or more of a mineral oil defoaming agent, a silicone defoaming agent, and a polyether defoaming agent.

8. The reflective heat-insulating sand wall paint according to claim 1, characterized in that: The coating additives include one or more of a thickener, a bactericide, and an anti-settling agent.

9. A method for preparing the reflective heat-insulating sand wall paint according to any one of claims 1 to 8, characterized in that: The steps include: S1, mixing the modified silica sol, sodium silicate, quartz sand, reflective heat-insulating pigment and co-solvent according to a ratio and sintering the mixture to obtain reflective heat-insulating sintered colored sand; S2, mixing the modified acrylic ester emulsion, the acid-base regulator, the film-forming aid, the multifunctional aid and the defoaming agent according to a ratio to obtain a modified composite emulsion; S3, mixing the reflective heat-insulating sintered colored sand, the modified composite emulsion, the coating additive and water according to a proportion to obtain a reflective heat-insulating sand wall paint.

10. A reflective heat-insulating coating, characterized in that: The reflective heat-insulating sand wall paint is obtained by coating the reflective heat-insulating sand wall paint according to any one of claims 1 to 8 on the surface of a substrate and drying the paint completely.

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