Water-based heat-insulating and cooling coating and preparation method thereof

Abstract

The invention provides a water-based heat-insulating and cooling coating and a preparation method thereof. The water-based heat-insulating and cooling coating is prepared from the following components in parts by weight: 5 to 25 parts of carboxymethyl cellulose aerogel powder, 20 to 50 parts of waterborne polyurethane emulsion, 10 to 50 parts of deionized water, 0.5 to 2.5 parts of wetting penetrant, 0.5 to 5 parts of emulsifier, 10 to 45 parts of nano SiO2, 0.5 to 4 parts of defoaming agent and 0.5 to 4 parts of bactericide. The preparation method comprises the following steps: firstly preparing carboxymethyl cellulose aerogel powder, then reacting the carboxymethyl cellulose aerogel powder with waterborne polyurethane emulsion under the action of a wetting penetrant and an emulsifier, and then adding nano silicon dioxide for blending to form the coating with heat-insulating and cooling effects. The coating disclosed by the invention combines the advantages of adhesion performance of polyurethane and heat insulation performance of carboxymethyl cellulose aerogel, the adhesion of the coating can reach 1.5 Mpa, and the heat conductivity coefficient is as low as 0.036 W / (mk); the heat-insulating and cooling coating is good in water-based property, safe and environmentally friendly, the preparation process is simple, and continuous production can be achieved.

Description

Technical Field

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

[0002] Energy conservation and thermal insulation of buildings are important ways to create a comfortable and green living environment. From the perspective of market demand, good thermal insulation performance makes coatings more popular with consumers. In 2019, China's architectural coatings output was 6.94 million tons. Based on a certain growth rate, it is expected that by 2030, my country's architectural coatings output will reach 11.06 million tons. Among them, aerogel thermal insulation coatings, which have excellent performance, are expected to have a market penetration rate of 10%, and the potential market in this field is about 6 billion yuan.

[0003] Carboxymethyl cellulose aerogel powder has good thermal insulation performance due to its porous structure. Carboxymethyl cellulose aerogel is a powder with air as the main component, which is hydrophobically modified to form a porous structure, and has extremely low density, low thermal conductivity, and high solar reflectivity. Waterborne polyurethane resin is an important coating emulsion with good bonding ability, good bonding performance to various substrates, good weather resistance, and green and pollution-free. It is widely used in the coating industry. Combining the excellent performance of the two to prepare coatings with thermal insulation and cooling properties has attracted widespread attention from researchers.

[0004] However, when preparing coatings, because hydrophobic powders are difficult to wet, more researchers use polar solvents such as toluene and xylene to dissolve carboxymethyl cellulose aerogel powders. However, the use of polar solvents will cause new pollution to the environment and also increase the cost of coatings. When preparing coatings in water-based systems, on the one hand, it is necessary to overcome the difficulty of carboxymethyl cellulose powder being wetted by water, which makes it difficult to add the powder into the coating. On the other hand, it is necessary to overcome the agglomeration of carboxymethyl cellulose, which causes the powder to be unevenly distributed in the coating, ultimately reducing the reflectivity and thermal insulation and fireproof properties of the coating.

[0005] Patent CN112759994A discloses a method for preparing an aerogel dispersion paste, which uses aerogel, mica powder and titanium dioxide as functional fillers and silicone-acrylic emulsion as the main film-forming material to prepare a dispersion paste with high thermal reflectivity. However, due to the extremely low water content and the water absorption properties of mica powder and titanium dioxide, the prepared dispersion paste will release a large amount of internal stress during the drying process of the silicone-acrylic emulsion after construction, resulting in low adhesion of the coating; the silicone-acrylic emulsion can reduce the surface tension of the system, which will make it difficult for the aerogel powder to be evenly dispersed in the coating, resulting in low thermal insulation performance of the final coating.

[0006] Patent CN117264505A discloses a method for preparing SiO2 aerogel coatings. The patent uses modified SiO2 as the main component of thermal insulation, adds bisphenol A and curing agent as the main film-forming substances, and prepares water-based aerogel coatings. However, due to the porous structure formed by SiO2 and the high hardness of the coating after forming the coating with bisphenol A, the adhesion of the coating on the substrate is low. The high-hardness coating will cause the aerogel powder to be squeezed during the drying process, destroying its hollow structure, which will eventually lead to low thermal insulation performance of the coating. Summary of the invention

[0007] In order to address the deficiencies in the prior art, the main purpose of the present invention is to provide a water-based thermal insulation and cooling coating and a preparation method thereof. The thermal insulation and cooling coating of the present invention combines the advantages of the adhesion properties of polyurethane and the thermal insulation properties of carboxymethyl cellulose aerogel, and its adhesion can reach 1.5Mpa, and the thermal conductivity coefficient is as low as 0.036W / (m•k). It has good adhesion and thermal insulation properties. Moreover, the thermal insulation and cooling coating has good water properties, is safe and environmentally friendly, has a simple preparation method, and is easy to industrialize.

[0008] In the first aspect, the present invention provides a water-based heat insulation and cooling material, which adopts the following technical solution: A water-based heat-insulating and cooling paint comprises the following components by weight: 5-25 parts of carboxymethyl cellulose aerogel powder, 20-50 parts of water-based polyurethane emulsion, 10-50 parts of deionized water, 0.5-2.5 parts of wetting and penetrating agent, 0.5-5 parts of emulsifier, 10-45 parts of nano-SiO2, 0.5-4 parts of defoamer and 0.5-4 parts of bactericide.

[0009] Preferably, the carboxymethyl cellulose aerogel powder comprises the following raw materials in parts by weight: 0.5-10 parts of gluconolactone, 20-50 parts of deionized water, 4-10 parts of sodium carboxymethyl cellulose, 1-6 parts of ferric chloride hexahydrate, 0.5-3 parts of ammonia water, 1-10 parts of dimethyldimethoxysilane, and 30-80 parts of ethanol.

[0010] Preferably, the carboxymethyl cellulose aerogel powder is a fine powder with a porous structure formed by dissolving, gelling and drying carboxymethyl cellulose.

[0011] Preferably, the preparation method of the carboxymethyl cellulose aerogel powder is as follows: (1) dissolving gluconolactone in deionized water to obtain a gluconolactone aqueous solution; then adding sodium carboxymethyl cellulose to the gluconolactone aqueous solution to obtain a clear and transparent solution, i.e., a sodium carboxymethyl cellulose solution; dissolving FeCl3·6H2O in deionized water, adjusting the pH of the solution with ammonia water, adding the FeCl3 solution to the sodium carboxymethyl cellulose solution, stirring, and placing the stirred solution at room temperature to allow gel aging; (2) dissolving dimethyldiethoxysilane in ethanol, then pouring the solution into the above gel for hydrophobic modification, placing the modified gel in a freeze dryer for drying, and crushing the dried gel to obtain carboxymethyl cellulose aerogel powder.

[0012] The invention performs composite modification on the carboxymethyl cellulose aerogel by means of chemical crosslinking, physical aging and hydrophobic modification, thereby improving the structural strength and stability of the coating.

[0013] Preferably, the aqueous polyurethane emulsion has a molecular weight of 50,000 to 150,000 and a solid content of 25% to 35%.

[0014] Preferably, the emulsifier is a mixture of anionic surfactant sodium dodecylbenzene sulfonate and nonionic surfactant Tween 80, with a mass ratio of 0.5-1.5:1.5-2.5.

[0015] Preferably, the wetting and penetrating agent is one or more of triethanolamine oleate, cellulose ether, dodecyl polyoxyethylene ether, and fatty alcohol polyoxyethylene ether (penetrant JFC).

[0016] Preferably, the defoamer is one or more of an organosilicon defoamer, a polyether defoamer, and a quaternary ammonium salt surfactant.

[0017] Preferably, the bactericide is one or more of a guanidine bactericide and a cationic bactericide.

[0018] In a second aspect, the present invention provides a method for preparing a water-based heat-insulating and cooling coating, comprising the following steps: S1, adding the aqueous polyurethane emulsion into deionized water to obtain an aqueous polyurethane dilution solution, adding a wetting and penetrating agent, and stirring evenly to obtain a first mixed solution; S2, adding an emulsifier to the first mixed solution, stirring evenly, to obtain a second mixed solution; S3. Add carboxymethyl cellulose aerogel powder to the second mixed solution and stir to dissolve; then add nano-SiO2 and stir evenly, then add defoamer and bactericide and stir to obtain heat insulation and cooling coating.

[0019] On the other hand, the present invention provides the use of the water-based heat-insulating and cooling coating in the field of construction.

[0020] Compared with the prior art, the present invention has the following beneficial effects: 1. When preparing a water-based heat-insulating and cooling coating, the present invention first mixes a water-based polyurethane emulsion with a wetting penetrant and an emulsifier to obtain a mixed solution, and then adds carboxymethyl cellulose aerogel powder for miscibility, thereby solving the problem of uneven distribution in the coating. Due to its unique porous structure, the coating has good heat-insulating effect and reflectivity. The present invention combines water-based polyurethane emulsion and carboxymethyl cellulose aerogel powder, fully utilizing the advantages of both, and further optimizing the heat-insulating performance of the coating through synergistic effects.

[0021] 2. The present invention introduces carboxymethyl cellulose aerogel powder and nano-silicon dioxide with a porous structure to prepare a water-based thermal insulation and cooling coating, which has stable thermal insulation and cooling performance and strong thermal insulation function. It can be used as a thermal insulation layer for the exterior wall of a building, effectively improving the energy-saving and thermal insulation effect of the building.

[0022] 3. The present invention adds composite modified carboxymethyl cellulose aerogel powder and aqueous polyurethane emulsion, so that the prepared coating has barrier properties, reflectivity and radiation protection, thereby improving the weather resistance, mechanical strength and heat insulation and cooling performance of the coating.

[0023] 4. The present invention adjusts the dosage of each component of the heat-insulating and cooling coating to achieve an adhesion of 1.5MPa and a thermal conductivity as low as 0.038W / (m•k). Using a 2mm thick coating can reduce the temperature in the liquid storage tank by 10°C. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present invention will be further described below in conjunction with the accompanying drawings: Figure 1 This is a real picture of the water-based heat-insulating and cooling paint of the present invention. DETAILED DESCRIPTION

[0025] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0026] Embodiment 1: A water-based heat-insulating and cooling paint comprises the following components in parts by weight: 5 parts of carboxymethyl cellulose aerogel powder, 20 parts of water-based polyurethane emulsion, 10 parts of deionized water, 0.5 parts of penetrant JFC, 0.5 parts of sodium dodecylbenzene sulfonate, 1 part of Tween 80, 10 parts of nano-SiO2, 0.5 parts of polydimethylsiloxane (molecular weight 10000-20000), and 0.5 parts of polyhexamethylene biguanide.

[0027] The preparation method of the water-based heat-insulating and cooling coating comprises the following steps: S1, adding 20 parts of aqueous polyurethane emulsion dropwise into 10 parts of deionized water, stirring for 60 minutes to obtain an aqueous polyurethane dilution, adding 0.5 parts of penetrant JFC to the dilution, stirring for 30 minutes, and obtaining a first mixed solution; S2, adding 0.5 parts of sodium dodecylbenzene sulfonate and 1 part of Tween 80 to the first mixed solution, and continuing stirring for 30 minutes to obtain a second mixed solution; S3. Slowly add 5 parts of carboxymethyl cellulose aerogel powder to the second mixed liquid and stir for 60 minutes until it is completely dissolved; then add 10 parts of nano-SiO2 and stir at high speed for 30 minutes until the powder is evenly dispersed in the mixed liquid, then add 0.5 parts of polydimethylsiloxane and 0.5 parts of polyhexamethylene biguanide and stir for 60 minutes to obtain a water-based thermal insulation and cooling coating.

[0028] The carboxymethyl cellulose aerogel powder includes the following raw materials by weight: 0.5 parts of gluconolactone, 20 parts of deionized water, 4 parts of sodium carboxymethyl cellulose, 1 part of ferric chloride hexahydrate, 0.5 parts of ammonia water, 1 part of dimethyldimethoxysilane, and 30 parts of ethanol; and the preparation method thereof is as follows: (1) 1 part of gluconolactone was added to 20 parts of deionized water and stirred for 20 minutes until it was completely dissolved to obtain a gluconolactone aqueous solution; then 5 parts of sodium carboxymethyl cellulose were added to the gluconolactone aqueous solution and stirred for 60 minutes to obtain a clear and transparent solution, i.e., sodium carboxymethyl cellulose solution; 1 part of FeCl3·6H2O was dissolved in 20 parts of deionized water, and the pH of the solution was adjusted to 7.0 with 1 part of ammonia water; FeC l3 The solution is added into the sodium carboxymethyl cellulose solution and stirred thoroughly. The stirred solution is placed at room temperature to allow gel aging; (2) Dissolve 1 part of dimethyldiethoxysilane in 30 parts of ethanol, then pour the solution into the above gel for hydrophobic modification for 24 hours, finally put the modified gel into a freeze dryer for vacuum drying for 72 hours, and grind the obtained solid to obtain aerogel powder.

[0029] Embodiment 2: A water-based heat-insulating and cooling paint comprises the following components by weight: 25 parts of carboxymethyl cellulose aerogel powder, 50 parts of water-based polyurethane emulsion, 50 parts of deionized water, 2.5 parts of penetrant JFC, 1 part of sodium dodecylbenzene sulfonate, 2 parts of Tween 80, 45 parts of nano-SiO2, 4 parts of polydimethylsiloxane, and 4 parts of polyhexamethylene biguanide.

[0030] The preparation method of the water-based heat-insulating and cooling coating comprises the following steps: S1, adding 50 parts of aqueous polyurethane emulsion dropwise into 50 parts of deionized water, stirring for 40 minutes to obtain an aqueous polyurethane dilution, adding 2.5 parts of penetrant JFC to the dilution, stirring for 60 minutes, and obtaining a first mixed solution; S2, adding 1 part of sodium dodecylbenzene sulfonate and 2 parts of Tween 80 to the first mixed solution, and continuing stirring for 30 minutes to obtain a second mixed solution; S3. Slowly add 25 parts of carboxymethyl cellulose aerogel powder to the second mixed liquid and stir for 60 minutes until it is completely dissolved; then add 45 parts of nano-SiO2 and stir at high speed for 30 minutes until the powder is evenly dispersed in the mixed liquid, then add 4 parts of polydimethylsiloxane and 4 parts of polyhexamethylene biguanide and stir for 60 minutes to obtain a water-based thermal insulation and cooling coating.

[0031] The carboxymethyl cellulose aerogel powder includes the following raw materials by weight: 10 parts of gluconolactone, 50 parts of deionized water, 10 parts of sodium carboxymethyl cellulose, 6 parts of ferric chloride hexahydrate, 3 parts of ammonia water, 10 parts of dimethyldimethoxysilane, and 80 parts of ethanol; and the preparation method thereof is as follows: (1) 10 parts of gluconolactone are added to 50 parts of deionized water and stirred for 25 minutes until the solution is completely dissolved to obtain a gluconolactone aqueous solution; then 10 parts of sodium carboxymethyl cellulose are added to the gluconolactone aqueous solution and stirred for 45 minutes to obtain a clear and transparent solution, i.e., a sodium carboxymethyl cellulose solution; 6 parts of FeCl3·6H2O are dissolved in 50 parts of deionized water, and the pH value of the solution is adjusted to 7.0 with 3 parts of ammonia water, and the FeCl3 solution is added to the sodium carboxymethyl cellulose solution and stirred sufficiently, and the stirred solution is left at room temperature to gel and age; (2) 10 parts of dimethyldiethoxysilane were dissolved in 80 parts of ethanol, and the solution was then poured into the above gel for hydrophobic modification for 24 hours. Finally, the modified gel was placed in a freeze dryer for vacuum drying for 72 hours, and the obtained solid was ground to obtain aerogel powder.

[0032] Embodiment 3: A water-based heat-insulating and anti-rust coating comprises the following components by weight: 12 parts of carboxymethyl cellulose aerogel powder, 30 parts of water-based polyurethane emulsion, 30 parts of deionized water, 1 part of penetrant JFC, 1 part of sodium dodecylbenzene sulfonate, 2 parts of Tween 80, 23 parts of nano-SiO2, 1.5 parts of polydimethylsiloxane and 1.5 parts of polyhexamethylene biguanide.

[0033] The preparation method of the water-based heat-insulating and cooling coating comprises the following steps: S1, adding 30 parts of aqueous polyurethane emulsion dropwise into 30 parts of deionized water, stirring for 60 minutes to obtain an aqueous polyurethane dilution, adding 1 part of penetrant JFC to the dilution, stirring for 60 minutes, and obtaining a first mixed solution; S2, adding 1 part of sodium dodecylbenzene sulfonate and 2 parts of Tween 80 to the first mixed solution, and continuing stirring for 30 minutes to obtain a second mixed solution; S3. Slowly add 12 parts of carboxymethyl cellulose aerogel powder to the second mixed liquid and stir for 60 minutes until it is completely dissolved; then add 23 parts of nano-SiO2 and stir at high speed for 30 minutes until the powder is evenly dispersed in the mixed liquid, then add 1.5 parts of polydimethylsiloxane and 1.5 parts of polyhexamethylene biguanide and stir for 60 minutes to obtain a water-based thermal insulation and cooling coating.

[0034] The carboxymethyl cellulose aerogel powder includes the following raw materials by weight: 3 parts of gluconolactone, 30 parts of deionized water, 7 parts of sodium carboxymethyl cellulose, 2 parts of ferric chloride hexahydrate, 1.5 parts of ammonia water, 2 parts of dimethyldimethoxysilane, and 45 parts of ethanol; and the preparation method thereof is as follows: (1) 3 parts of gluconolactone are added to 20 parts of deionized water and stirred for 45 minutes until the solution is completely dissolved to obtain a gluconolactone aqueous solution; then 7 parts of sodium carboxymethyl cellulose are added to the gluconolactone aqueous solution and stirred for 60 minutes to obtain a clear and transparent solution, i.e., a sodium carboxymethyl cellulose solution; 2 parts of FeCl3·6H2O are dissolved in 10 parts of deionized water, and the pH value of the solution is adjusted to 7.0 with 1.5 parts of ammonia water, and the FeCl3 solution is added to the sodium carboxymethyl cellulose solution and stirred sufficiently, and the stirred solution is left at room temperature to gel and age; (2) Dissolve 2 parts of dimethyldiethoxysilane in 45 parts of ethanol, then pour the solution into the above gel for hydrophobic modification for 24 hours, finally put the modified gel into a freeze dryer for vacuum drying for 72 hours, and grind the obtained solid to obtain aerogel powder.

[0035] Embodiment 4: A water-based heat-insulating and anti-rust coating comprises the following components by weight: 15 parts of carboxymethyl cellulose aerogel powder, 50 parts of water-based polyurethane emulsion, 20 parts of deionized water, 0.5 parts of penetrant JFC, 0.5 parts of sodium dodecylbenzene sulfonate, 1 part of Tween 80, 30 parts of nano-SiO2, 3 parts of polydimethylsiloxane and 3 parts of polyhexamethylene biguanide.

[0036] The preparation method of the water-based heat-insulating and cooling coating comprises the following steps: S1, adding 50 parts of aqueous polyurethane emulsion dropwise into 20 parts of deionized water, stirring for 40 minutes to obtain an aqueous polyurethane dilution, adding 0.5 parts of penetrant JFC to the dilution, stirring for 60 minutes, and obtaining a first mixed solution; S2, adding 0.5 parts of sodium dodecylbenzene sulfonate and 1 part of Tween 80 to the first mixed solution, and continuing stirring for 30 minutes to obtain a second mixed solution; S3. Slowly add 10 parts of carboxymethyl cellulose aerogel powder to the second mixed liquid and stir for 60 minutes until it is completely dissolved; then add 30 parts of nano-SiO2 and stir at high speed for 30 minutes until the powder is evenly dispersed in the mixed liquid, then add 3 parts of polydimethylsiloxane and 3 parts of polyhexamethylene biguanide and stir for 60 minutes to obtain a water-based thermal insulation and cooling coating.

[0037] The carboxymethyl cellulose aerogel powder comprises the following raw materials by weight: 5 parts of gluconolactone, 20 parts of deionized water, 5 parts of sodium carboxymethyl cellulose, 2 parts of ferric chloride hexahydrate, 0.5 parts of ammonia water, 5 parts of dimethyldimethoxysilane, and 60 parts of ethanol; and the preparation method thereof is as follows: (1) 5 parts of gluconolactone are added to 15 parts of deionized water and stirred for 35 minutes until the solution is completely dissolved to obtain a gluconolactone aqueous solution; then 5 parts of sodium carboxymethyl cellulose are added to the gluconolactone aqueous solution and stirred for 65 minutes to obtain a clear and transparent solution, i.e., a sodium carboxymethyl cellulose solution; 2 parts of FeCl3·6H2O are dissolved in 5 parts of deionized water, and the pH value of the solution is adjusted to 7.0 with 0.5 parts of ammonia water, and the FeCl3 solution is added to the sodium carboxymethyl cellulose solution and stirred sufficiently, and the stirred solution is left at room temperature to gel and age; (2) Dissolve 5 parts of dimethyldiethoxysilane in 60 parts of ethanol, then pour the solution into the above gel for hydrophobic modification for 24 hours, finally put the modified gel into a freeze dryer for vacuum drying for 72 hours, and grind the obtained solid to obtain aerogel powder.

[0038] Embodiment 5: A water-based heat-insulating and cooling paint comprises the following components by weight: 15 parts of carboxymethyl cellulose aerogel powder, 40 parts of water-based polyurethane emulsion, 15 parts of deionized water, 2 parts of penetrant JFC, 0.5 parts of sodium dodecylbenzene sulfonate, 1 part of Tween 80, 35 parts of nano-SiO2, 2 parts of polydimethylsiloxane, and 2 parts of polyhexamethylene biguanide.

[0039] The preparation method of the water-based heat-insulating and cooling coating comprises the following steps: S1, adding 45 parts of aqueous polyurethane emulsion dropwise into 15 parts of deionized water, stirring for 40 minutes to obtain an aqueous polyurethane dilution, adding 2 parts of penetrant JFC to the dilution, stirring for 60 minutes, and obtaining a first mixed solution; S2, adding 0.5 parts of sodium dodecylbenzene sulfonate and 1 part of Tween 80 to the first mixed solution, and continuing stirring for 30 minutes to obtain a second mixed solution; S3. Add 15 parts of carboxymethyl cellulose aerogel powder to the second mixed liquid and stir for 60 minutes until it is completely dissolved; then add 35 parts of nano-SiO2 and stir at high speed for 30 minutes until the powder is evenly dispersed in the mixed liquid, then add 2 parts of polydimethylsiloxane and 2 parts of polyhexamethylene biguanide and stir for 60 minutes to obtain a water-based thermal insulation and cooling coating.

[0040] The carboxymethyl cellulose aerogel powder comprises the following raw materials by weight: 7 parts of gluconolactone, 30 parts of deionized water, 8 parts of sodium carboxymethyl cellulose, 4 parts of ferric chloride hexahydrate, 2 parts of ammonia water, 8 parts of dimethyldimethoxysilane, and 60 parts of ethanol; and the preparation method thereof is as follows: (1) 7 parts of gluconolactone are added to 15 parts of deionized water and stirred for 30 minutes until the solution is completely dissolved to obtain a gluconolactone aqueous solution; then 8 parts of sodium carboxymethyl cellulose are added to the gluconolactone aqueous solution and stirred for 55 minutes to obtain a clear and transparent solution, i.e., a sodium carboxymethyl cellulose solution; 4 parts of FeCl3·6H2O are dissolved in 15 parts of deionized water, and the pH value of the solution is adjusted to 7.0 with 2 parts of ammonia water, and the FeCl3 solution is added to the sodium carboxymethyl cellulose solution and stirred sufficiently, and the stirred solution is left at room temperature to gel and age; (2) 8 parts of dimethyldiethoxysilane were dissolved in 60 parts of ethanol, and the solution was then poured into the above gel for hydrophobic modification for 24 hours. Finally, the modified gel was placed in a freeze dryer for vacuum drying for 72 hours, and the obtained solid was ground to obtain aerogel powder.

[0041] The water-based heat-insulating and cooling coating prepared in this embodiment was scraped onto the surface of a stainless steel storage tank in a batch-scraping manner to form a 2 mm thick coating. In a windless environment, at an outdoor temperature of 40°C, a thermocouple was used to record the temperature of the aqueous solution inside the storage tank with and without a 2 mm thick coating. By comparison, it was found that the temperature of the aqueous solution inside the storage tank with a 2 mm thick coating was 30°C, and the temperature of the aqueous solution inside the storage tank without a 2 mm thick coating was 40°C. The results showed that a 2 mm thick coating could insulate 10°C, reducing the temperature inside the liquid storage tank to 30°C.

[0042] Comparative Example 1: Compared with Example 5, the only difference is that the carboxymethyl cellulose aerogel powder includes the following raw materials in parts by weight: 10 parts of gluconolactone, 20 parts of deionized water, 10 parts of sodium carboxymethyl cellulose, 2 parts of aluminum chloride trihydrate, 2 parts of ammonia water, 8 parts of dimethyldimethoxysilane, and 60 parts of ethanol; and its preparation method is as follows: (1) 10 parts of sodium carboxymethyl cellulose were added to 20 parts of deionized water, and stirred for 30 minutes to form a suspension. Then, 10 parts of gluconolactone were added dropwise to the suspension, and stirred for 60 minutes. Then, 2 parts of AlCl3•3H2O were added and stirred for 24 hours to obtain a suspension. Then, the pH of the suspension was adjusted to 7.0 with 2 parts of ammonia water, and the suspension was centrifuged for 15 minutes and then introduced into a mold to form a gel. (2) 8 parts of dimethyldiethoxysilane were dissolved in 60 parts of ethanol, and then the solution was poured into a mold to hydrophobically modify the gel for 24 hours. Finally, the modified gel was placed in a freeze dryer for vacuum drying for 72 hours, and the obtained solid was ground to obtain aerogel powder.

[0043] The preparation method of the water-based thermal insulation and cooling coating is the same as that of Example 5.

[0044] Comparative Example 2: Compared with Example 5, the only difference is that the water-based thermal insulation coating includes the following components in parts by weight: 15 parts of carboxymethyl cellulose aerogel powder, 15 parts of deionized water, 2 parts of penetrant JFC, 0.5 parts of sodium dodecylbenzene sulfonate, 1 part of Tween 80, 35 parts of nano-SiO2, 2 parts of polydimethylsiloxane, and 2 parts of polyhexamethylene biguanide.

[0045] The preparation method of the water-based thermal insulation coating comprises the following steps: S1. Add 2 parts of wetting and penetrating agent to 15 parts of deionized water and stir for 60 minutes to obtain a first mixed solution; S2, adding 0.5 parts of sodium dodecylbenzene sulfonate and 1 part of Tween 80 to the first mixed solution, and continuing stirring for 30 minutes to obtain a second mixed solution; S3. Add 15 parts of carboxymethyl cellulose aerogel powder to the second mixed solution and stir for 60 minutes to dissolve; then add 35 parts of nano-SiO2 and stir at high speed for 30 minutes until the powder is evenly dispersed in the mixed solution, then add 2 parts of polydimethylsiloxane and 2 parts of polyhexamethylene biguanide and stir for 60 minutes to obtain a water-based thermal insulation coating.

[0046] The composition and preparation of the carboxymethyl cellulose aerogel powder are the same as those in Example 5.

[0047] The performance of the water-based heat-insulating and cooling coatings prepared in the above Examples 1-5 and Comparative Examples 1-2 was tested, and the specific test standards are as follows: (1) Thermal conductivity is tested according to GB / T10294-2008; (2) Solar reflectance is tested according to ASTM C1594-16; (3) Hemispherical emissivity is tested according to ASTM C1371-15; (4) Non-volatile matter content is tested according to GB / T1725-2007, and the drying time (GB / T1728-2004) is 45 minutes for surface drying and 15 hours for actual drying; (5) Adhesion is tested by the pull-off method (GB / T 5210-2006); (6) Water and alkali resistance of coatings standard HG / T4341-2012.

[0048] The specific test results are shown in Table 1.

[0049] Table 1 Performance test results of water-based heat-insulating and cooling coatings prepared in Examples and Comparative Examples

[0050] From the test results of Table 1, it can be seen that the solar reflectance and hemispherical emissivity of the water-based thermal insulation and cooling coating prepared by the present invention are respectively 0.89 and 0.91 at the highest, and the water and alkali resistance of the coating are qualified, the thermal conductivity is as low as 0.036W / (m•k), the adhesion reaches 1.5MPa, and while having basic properties, the mechanical properties and stability of the coating are improved, and it has a strong thermal insulation and cooling effect. The coating prepared by Example 5 of the present invention has the best performance.

[0051] In Examples 1-5, the thermal conductivity and adhesion of the water-based thermal insulation and cooling coating obtained in Example 5 are 0.036W / (m•k) and 1.5MPa, respectively, which are lower than those in Example 1-4, indicating that the raw material dosage of the water-based thermal insulation and cooling coating in Example 5 is more appropriate, which improves the stability and thermal insulation and cooling performance of the coating. Compared with Example 5, Comparative Example 1-2 has poor thermal insulation and heat preservation performance or adhesion. The above results show that the present invention combines the advantages of the adhesion performance of polyurethane and the thermal insulation performance of carboxymethyl cellulose aerogel, and further optimizes the thermal insulation performance and adhesion of the coating through the synergistic effect of the two, and significantly improves the thermal insulation and cooling effect of the coating.

[0052] The above embodiments are only preferred technical solutions of the present invention and should not be regarded as limiting the present invention. The protection scope of the present invention shall be the technical solutions recorded in the claims, including equivalent replacement solutions of the technical features in the technical solutions recorded in the claims. That is, equivalent replacement improvements within this scope are also within the protection scope of the present invention.

Claims

1. A water-based heat-insulating and cooling coating, characterized in that: The invention comprises the following components by weight: 5-25 parts of carboxymethyl cellulose aerogel powder, 20-50 parts of waterborne polyurethane emulsion, 10-50 parts of deionized water, 0.5-2.5 parts of wetting and penetrating agent, 0.5-5 parts of emulsifier, 10-45 parts of nano-SiO2, 0.5-4 parts of defoaming agent and 0.5-4 parts of bactericide.

2. The water-based heat-insulating and cooling coating according to claim 1, characterized in that: The carboxymethyl cellulose aerogel powder comprises the following raw materials in parts by weight: 0.5-10 parts of gluconolactone, 20-50 parts of deionized water, 4-10 parts of sodium carboxymethyl cellulose, 1-6 parts of ferric chloride hexahydrate, 0.5-3 parts of ammonia water, 1-10 parts of dimethyldimethoxysilane, and 30-80 parts of ethanol.

3. The water-based heat-insulating and cooling paint according to claim 2, characterized in that: The carboxymethyl cellulose aerogel powder is a fine powder with a porous structure formed by dissolving, gelling and drying carboxymethyl cellulose.

4. The water-based heat-insulating and cooling paint according to claim 2, characterized in that: The preparation method of the carboxymethyl cellulose aerogel powder is as follows: (1) dissolving gluconolactone in deionized water to obtain a gluconolactone aqueous solution; then adding sodium carboxymethyl cellulose to the gluconolactone aqueous solution to obtain a clear and transparent solution, i.e., a sodium carboxymethyl cellulose solution; dissolving FeCl3·6H2O in deionized water, adjusting the pH of the solution with ammonia water, adding the FeCl3 solution to the sodium carboxymethyl cellulose solution, stirring, and placing the stirred solution at room temperature to allow gel aging; (2) dissolving dimethyl diethoxysilane in ethanol, then pouring the solution into the above gel for hydrophobic modification, placing the modified gel in a freeze dryer for drying, and crushing the dried gel to obtain carboxymethyl cellulose aerogel powder.

5. The water-based heat-insulating and cooling paint according to claim 1, characterized in that: The aqueous polyurethane emulsion has a molecular weight of 50,000 to 150,000 and a solid content of 25% to 35%.

6. The water-based heat-insulating and cooling paint according to claim 1, characterized in that: The emulsifier is a mixture of anionic surfactant sodium dodecylbenzene sulfonate and nonionic surfactant Tween 80, with the proportion of 0.5-1.5:1.5-2.

5.

7. The water-based heat-insulating and cooling paint according to claim 1, characterized in that: The wetting and penetrating agent is one or more of triethanolamine oleate, cellulose ether, dodecyl polyoxyethylene ether, and fatty alcohol polyoxyethylene ether.

8. The water-based heat-insulating and cooling paint according to claim 1, characterized in that: The defoamer is one or more of an organosilicon defoamer, a polyether defoamer, and a quaternary ammonium salt surfactant; The bactericide is one or more of a guanidine bactericide and a cationic bactericide.

9. The method for preparing the water-based heat-insulating and cooling coating according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1, adding the aqueous polyurethane emulsion into deionized water to obtain an aqueous polyurethane dilution solution, adding a wetting and penetrating agent, and stirring evenly to obtain a first mixed solution; S2, adding sodium dodecylbenzene sulfonate and Tween 80 to the first mixed solution, stirring evenly to obtain a second mixed solution; S3. Add carboxymethyl cellulose aerogel powder to the second mixed solution and stir to dissolve; then add nano-SiO2 and stir evenly, then add defoamer and bactericide and stir to obtain a heat insulation and cooling coating.

10. Use of the water-based heat-insulating and cooling coating according to any one of claims 1 to 8 in the field of construction.

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