Single-component reflective heat-insulating polyurethane waterproof coating and preparation method thereof

Abstract

The invention relates to the technical field of building coatings, and discloses a single-component reflective heat-insulating polyurethane waterproof coating, which comprises the following raw materials by mass: 100-120 parts of deionized water; 1.5 to 2.5 parts of cellulose; 1 to 1.5 parts of a pH value regulator; 2-3 parts of a bactericide; 6-8 parts of a dispersant; 1.5 to 2 parts of a wetting agent; 2-5 parts of a defoaming agent; 15 to 20 parts of a coalescing agent; 150 to 200 parts of titanium dioxide; 250 to 350 parts of heat reflection powder; 100 to 150 parts of barium sulfate; 380 to 450 parts of a waterborne polyurethane emulsion; 3-5 parts of a leveling agent; and 1 to 1.5 parts of a thickening agent. According to the single-component reflective heat-insulating polyurethane waterproof coating and the preparation method, the prepared coating has excellent reflective heat-insulating performance on light waves and has good heat-insulating and cooling effects, a compact paint film can be formed after the coating is brushed, and the single-component reflective heat-insulating polyurethane waterproof coating has super-weather-resistant and high-elasticity waterproof functions.

Description

Technical Field

[0001] The present invention relates to the technical field of architectural coatings, and particularly to a one-component reflective heat-insulating polyurethane waterproof coating and a preparation method thereof. Background Art

[0002] When sunlight shines on the surface of a building, it will increase the internal temperature of the building. In summer, it will increase the burden on the air-conditioning system, resulting in increased power consumption, thereby increasing energy consumption and carbon dioxide emissions. The solar radiation energy is mainly electromagnetic waves in the near-infrared band, with a wavelength range of 230 - 5000 nm. The research on reflective heat-insulating materials has always been highly valued by the market. Reflective heat-insulating coatings utilize their special reflective ability on the surface to reflect sunlight back, thereby reducing sunlight irradiation, ultraviolet radiation, and lowering the internal temperature of buildings. Heat-reflective powder can reflect light waves in the 590 - 2430 nm band, and it has a very high solar light reflectivity and thermal infrared reflectivity, generally reaching more than 90%. It is particularly suitable for the surfaces of buildings such as roofs, walls, and windows that require heat-insulating treatment.

[0003] In the prior art, there are also some reflective heat-insulating and waterproof related coatings. For example, a Chinese invention patent with the application number CN201811304356.9 and the name of an insulating and anticorrosive two-component coating for the outer wall of an oil tank and its preparation method has a very high reflectivity. It can not only reflect solar radiation well but also play the role of heat insulation and temperature reduction. The coating also has excellent film hardness, abrasion resistance, alkali resistance, and water resistance. However, it consists of component A and component B, and separate operations are required during production, transportation, and use, which is rather inconvenient and the use cost is high.

[0004] Another example is a Chinese invention patent with the application number CN201811304375.1 and the name of a reflective heat-insulating topcoat for exterior walls and its preparation method. It has a very high reflectivity, can not only reflect solar radiation well but also play the role of heat insulation and temperature reduction, and also has good weather resistance, adhesion, frost resistance, and other properties. However, it is mainly made of pure acrylic emulsion and has the disadvantages of being thermally sticky and cold brittle. The content of its heat-reflective powder is also relatively low, and there is room for improvement in its ability to reflect solar radiation. Summary of the Invention

[0005] In order to overcome the deficiencies of the prior art, the purpose of the present invention is to provide a one-component reflective heat-insulating polyurethane waterproof coating and a preparation method thereof. The prepared coating has excellent reflective heat-insulating performance for light waves, has a good heat insulation and temperature reduction effect, and can also form a dense paint film after brushing, with super weather resistance and high-elastic waterproof function.

[0006] The present invention is realized by the following technical solutions: A one-component reflective heat-insulating polyurethane waterproof coating, which comprises the following raw materials in parts by mass: deionized water: 100 - 120 parts; cellulose: 1.5 - 2.5 parts; pH value regulator: 1 - 1.5 parts; bactericide: 2 - 3 parts; dispersant: 6 - 8 parts; wetting agent: 1.5 - 2 parts; defoamer: 2 - 5 parts; film-forming auxiliary agent: 15 - 20 parts; titanium dioxide: 150 - 200 parts; heat-reflective powder: 250 - 350 parts; barium sulfate: 100 - 150 parts; aqueous polyurethane emulsion: 380 - 450 parts; leveling agent: 3 - 5 parts; thickening agent: 1 - 1.5 parts.

[0007] Further, the aqueous polyurethane emulsion is an anionic aliphatic polyether polyurethane dispersion.

[0008] Further, the bactericide is 2-methyl-4-isothiazolin-3-one.

[0009] Further, the wetting agent is any one of polyoxyethylene alkylphenol ether, polyoxyethylene fatty alcohol ether, and polyoxyethylene-polyoxypropylene block copolymer.

[0010] Further, the cellulose is hydroxyethyl cellulose.

[0011] Further, the pH value regulator is a mixture of 2-amino-2-methyl-1-propanol and water.

[0012] Further, the heat-reflective powder is a high-whiteness near-infrared silicate reflective material, which is ground for 3 - 5 h using a planetary mill for pulverization and crushing to form a powder with 12,000 - 13,000 mesh, and the coarser particles are removed using a classifier to form a silicate solid powder with an average particle size of 1 μm.

[0013] Further, the dispersant is an ammonium polyacrylate salt dispersant; the titanium dioxide is rutile titanium dioxide; the film-forming auxiliary agent is dipropylene glycol methyl ether.

[0014] Further, the defoamer is a mineral oil defoamer; the leveling agent is a polyurethane leveling agent; the thickening agent is a polyurethane thickening agent.

[0015] A preparation method of a one-component reflective heat-insulating polyurethane waterproof coating, using the above one-component reflective heat-insulating polyurethane waterproof coating, comprises the following steps:

[0016] Step 1: Weigh the raw material components according to the ratio of the one-component reflective heat-insulating polyurethane waterproof coating, add deionized water to the reaction tank, and stir at a speed of 400 - 500 rpm;

[0017] Step 2: According to the raw material ratio, while stirring, successively add cellulose, dispersant, bactericide, wetting agent, and film-forming aid into water, and mix evenly; then continue to stir at a speed of 400 - 500 rpm for 4 - 6 min;

[0018] Step 3: Then successively add heat-reflective powder, titanium dioxide, and barium sulfate into the mixture obtained in Step 2, mix evenly, and stir at a dispersion speed of 1200 - 1600 rpm for 12 - 18 minutes until the paint slurry is uniform; make the fineness of the obtained liquid material ≤ 55 um;

[0019] Step 4: Add the aqueous polyurethane emulsion into the liquid material obtained in Step 3, mix evenly to obtain a paint slurry; stir at a speed of 800 - 1000 rpm for 4 - 6 min,

[0020] Step 5: Slowly add a pH regulator, defoamer, leveling agent, and thickener into the reaction tank where Step 4 is located for thickening, stir at a speed of 800 - 1000 rpm for 4 - 6 min, measure the initial viscosity, and adjust the viscosity to 100 - 105 KU to obtain a one-component reflective heat-insulating polyurethane waterproof coating.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] 1. For the one-component reflective heat-insulating polyurethane waterproof coating and its preparation method of the present invention, the prepared coating has excellent light wave reflection and heat insulation performance, and its solar reflectance, near-infrared reflectance, and hemispherical emissivity are all better than the technical indicators in the standard, having a good heat insulation and cooling effect. After being applied to the outer surface of a building, it can reflect most of the solar light and heat, achieving the purpose of reducing temperature.

[0023] 2. For the one-component reflective heat-insulating polyurethane waterproof coating and its preparation method of the present invention, the paint film formed after being applied to the outer surface of a building is dense, has super weather resistance and high-elastic waterproof function, and can also act as a waterproof coating.

[0024] 3. For the one-component reflective heat-insulating polyurethane waterproof coating and its preparation method of the present invention, it is a one-component coating, and its preparation, transportation, and use are more convenient. Specific Embodiments

[0025] The following specific examples illustrate the embodiments of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, without conflict, the following examples and the features in the examples can be combined with each other.

[0026] The object of the present invention is to provide a one-component reflective heat-insulating polyurethane waterproof coating and a preparation method thereof in view of the defects of the prior art.

[0027] Example 1

[0028] A one-component reflective heat-insulating polyurethane waterproof coating comprises the following raw materials in parts by mass:

[0029] Deionized water: 100-120 parts;

[0030] Cellulose: 1.5-2.5 parts;

[0031] pH value regulator: 1-1.5 parts;

[0032] Bactericide: 2-3 parts;

[0033] Dispersant: 6-8 parts;

[0034] Wetting agent: 1.5-2 parts;

[0035] Defoamer: 2-5 parts;

[0036] Film-forming aid: 15-20 parts;

[0037] Titanium dioxide: 150-200 parts;

[0038] Heat-reflective powder: 250-350 parts;

[0039] Barium sulfate: 100-150 parts;

[0040] Waterborne polyurethane emulsion: 380-450 parts;

[0041] Leveling agent: 3-5 parts;

[0042] Thickener: 1-1.5 parts.

[0043] The aqueous polyurethane emulsion therein is an anionic aliphatic polyether polyurethane dispersion. The fungicide is 2-methyl-4-isothiazolin-3-one. The wetting agent is any one of polyoxyethylene alkylphenol ether, polyoxyethylene fatty alcohol ether, and polyoxyethylene-polyoxypropylene block copolymer. The cellulose is hydroxyethyl cellulose. The pH value regulator is a mixture of 2-amino-2-methyl-1-propanol and water. The heat-reflective powder is a high-whiteness near-infrared silicate reflective material, which is ground for 3 to 5 hours using a planetary mill for pulverization and crushing to form a powder with 12,000 to 13,000 mesh, and a classifier is used to remove coarser particulate matter to form a silicate solid powder with an average particle size of 1 μm. The dispersant is an ammonium polyacrylate salt dispersant; the titanium dioxide is rutile titanium dioxide; the film-forming aid is dipropylene glycol methyl ether. The defoaming agent is a mineral oil defoaming agent; the leveling agent is a polyurethane leveling agent; the thickener is a polyurethane thickener.

[0044] A preparation method of a one-component reflective heat-insulating polyurethane waterproof coating uses the above-mentioned one-component reflective heat-insulating polyurethane waterproof coating and includes the following steps:

[0045] Step 1: Weigh the raw material components according to the ratio of the one-component reflective heat-insulating polyurethane waterproof coating, add deionized water to the reaction tank, and stir at a speed of 400 - 500 rpm.

[0046] Step 2: According to the raw material component ratio, under the stirring state, sequentially add cellulose, dispersant, fungicide, wetting agent, and film-forming aid into the water, and mix evenly; then continue to stir at a speed of 400 - 500 rpm for 4 - 6 minutes.

[0047] Step 3: Then sequentially add heat-reflective powder, titanium dioxide, and barium sulfate to the mixture obtained in Step 2, mix evenly, and stir at a dispersion speed of 1200 - 1600 rpm for 12 - 18 minutes until the paint slurry is uniform; make the fineness of the obtained liquid material ≤ 55 μm.

[0048] Step 4: Add the aqueous polyurethane emulsion to the liquid material obtained in Step 3, mix evenly to obtain a paint slurry; stir at a speed of 800 - 1000 rpm for 4 - 6 minutes.

[0049] Step 5: Slowly add the pH value regulator, defoaming agent, leveling agent, and thickener to the reaction tank in Step 4 for thickening, stir at a speed of 800 - 1000 rpm for 4 - 6 minutes, measure the initial viscosity, and adjust the viscosity to 100 - 105 KU to obtain the one-component reflective heat-insulating polyurethane waterproof coating.

[0050] Example Two

[0051] A one-component reflective heat-insulating polyurethane waterproof coating provided by the present invention comprises raw materials in the following parts by mass: 120 parts of deionized water; 2 parts of a bactericide; 2 parts of cellulose; 7 parts of a dispersant; 2 parts of a wetting agent; 15 parts of a film-forming auxiliary; 250 parts of a heat-reflective powder; 150 parts of titanium dioxide; 150 parts of barium sulfate; 380 parts of an aqueous polyurethane emulsion; 3 parts of an antifoaming agent; 5 parts of a leveling agent; 1.5 parts of a thickening agent; 1.5 parts of a pH regulator.

[0052] The aqueous polyurethane emulsion in this example is the 8355 emulsion, an anionic aliphatic polyether polyurethane dispersion produced by Wanhua Chemical Group Co., Ltd., which has excellent adhesion strength and durability and has the characteristic of low odor. The bactericide is 2-methyl-4-isothiazolin-3-one, which is a white crystalline solid under normal temperature and pressure and has good solubility, and is used to control the growth of microorganisms in the coating, improve the performance and quality of the coating, and extend its shelf life. The wetting agent is any one of polyoxyethylene alkylphenol ether, polyoxyethylene fatty alcohol ether, and polyoxyethylene-polyoxypropylene block copolymer. The wetting agent in this example is the LCN 407 wetting agent produced by Clariant, which is used to improve the color development property of the coating, improve the fluidity and scratch resistance of the coating. The cellulose is the 250 hydroxyethyl cellulose of the American company Ashland, which is easily dispersed and dissolved in water, can change the rheological properties of the coating, helps to maintain the stability of the coating, and plays the role of retaining moisture. The pH regulator is the mixture AMP-95 containing 95% of 2-amino-2-methyl-1-propanol and 5% of water developed and produced by The Dow Chemical Company, which is used to improve the pH stability of the coating, reduce flash rust on the surface of steel and iron, and can prevent pigment re-aggregation, improve the dispersion effect of pigments, reduce foam, and reduce the dosage of dispersants. The heat-reflective powder is a high-whiteness near-infrared silicate reflective material, which is made by mixing various mineral raw materials such as elements of aluminum, silicon, germanium, copper, etc., and the surface is modified, treated and coated with aluminum oxide, so that it has extremely high weather resistance and extremely high infrared reflectivity. In this example, in order to improve the photocatalytic stability of the new pigment, a dense silica coating is used to improve the durability. After two magnetic separations to remove iron, it is ground for 4 hours using a planetary mill for crushing and pulverizing, and made into a powder with a mesh size of 12,500, and then a classifier is used to remove coarser particles to make a silicate solid powder with an average particle size of 1 μm, which is used to increase the ultraviolet resistance and heat insulation of the coating. The pH regulator is the mixture AMP-95 containing 95% of 2-amino-2-methyl-1-propanol and 5% of water developed and produced by The Dow Chemical Company, which is used to improve the pH stability of the coating, reduce flash rust on the surface of steel and iron, and can prevent pigment re-aggregation, improve the dispersion effect of pigments, reduce foam, and reduce the dosage of dispersants.

[0053] The heat-reflective powder is a high-whiteness near-infrared silicate reflective material, which is made by mixing various mineral raw materials such as elements of aluminum, silicon, germanium, copper, etc., and the surface is modified, treated and coated with aluminum oxide, so that it has extremely high weather resistance and extremely high infrared reflectivity. In this example, in order to improve the photocatalytic stability of the new pigment, a dense silica coating is used to improve the durability. After two magnetic separations to remove iron, it is ground for 4 hours using a planetary mill for crushing and pulverizing, and made into a powder with a mesh size of 12,500, and then a classifier is used to remove coarser particles to make a silicate solid powder with an average particle size of 1 μm, which is used to increase the ultraviolet resistance and heat insulation of the coating.

[0054] The dispersant in this example is the SN-DISPERSANT 5027 modified ammonium polyacrylate polymer dispersant produced by Nopco, which is used to improve the gloss, water resistance of the coating and enhance the performance in terms of storage stability. The titanium dioxide is the R-996 rutile type titanium dioxide from Sichuan Longmang, which has high whiteness, good hiding power and excellent weather resistance; the barium sulfate is the YM-S6000 precipitated barium sulfate from Langfang Shuangma Chemical Co., Ltd., which can improve the abrasion resistance, weather resistance and gloss of the coating. The film-forming aid is dipropylene glycol methyl ether from Dow Chemical Company of the United States, which has good dissolution and coupling capabilities. The defoamer is the NXZ mineral oil defoamer from Nopco of Japan, which has a strong defoaming speed and defoaming suppression ability. The leveling agent is the RM-2020 polyurethane leveling agent produced by Dow Chemical Company, which is a non-toxic, odorless and environmentally friendly rheological modification aid, having a good brushing feel, good water resistance and strong scrub resistance. The thickener is the RM-8W modified polyurethane thickener produced by Dow Chemical Company, which can provide better flow and leveling properties, uniform film-forming performance, gloss display performance and high thickening efficiency, and can minimize the impact on the flow and leveling properties of the coating under high thickening efficiency.

[0055] The one-component reflective heat-insulating polyurethane waterproof coating of this example is prepared by the following preparation method:

[0056] Step 1: Weigh the raw material components according to the above ratio, add deionized water to the reaction tank, and stir at a speed of 450 rpm;

[0057] Step 2: According to the raw material component ratio, under the stirring state, sequentially add cellulose, dispersant, bactericide, wetting agent, and film-forming aid into the water, and mix evenly; then continue to stir at a speed of 450 rpm for 5 min;

[0058] Step 3: Then sequentially add heat-reflective powder, titanium dioxide, and barium sulfate to the mixture obtained in Step 2, mix evenly, and stir at a dispersion speed of 1400 rpm for 15 min until the paint slurry is uniform; make the fineness of the obtained liquid material ≤ 55 um;

[0059] Step 4: Add the aqueous polyurethane emulsion to the liquid material obtained in Step 3, mix evenly to obtain a paint slurry; stir at a speed of 900 rpm for 5 min,

[0060] Step 5: Slowly add the pH regulator, defoamer, leveling agent, and thickener to the reaction tank in Step 4, stir at a speed of 900 rpm for 5 min, measure the initial viscosity, 25 °C, Stormer viscometer 100 KU, to obtain the one-component reflective heat-insulating polyurethane waterproof coating.

[0061] Example 3

[0062] A one-component reflective heat-insulating polyurethane waterproof coating provided by the present invention comprises the following raw materials in parts by mass: 110 parts of deionized water; 2 parts of fungicide; 2 parts of cellulose; 7 parts of dispersant; 2 parts of wetting agent; 15 parts of film-forming aid; 300 parts of heat-reflective powder; 180 parts of titanium dioxide; 120 parts of barium sulfate; 410 parts of aqueous polyurethane emulsion; 3 parts of defoamer; 5 parts of leveling agent; 1 part of thickener; 1 part of pH regulator.

[0063] The preparation method of the one-component reflective heat-insulating polyurethane waterproof coating in this example is the same as that of the coating in Example 2.

[0064] Example 4

[0065] A one-component reflective heat-insulating polyurethane waterproof coating provided by the present invention comprises the following raw materials in parts by mass: 110 parts of deionized water; 2 parts of fungicide; 2 parts of cellulose; 6 parts of dispersant; 2 parts of wetting agent; 18 parts of film-forming aid; 350 parts of heat-reflective powder; 200 parts of titanium dioxide; 100 parts of barium sulfate; 450 parts of aqueous polyurethane emulsion; 3.5 parts of defoamer; 5 parts of leveling agent; 1.5 parts of thickener; 1 part of pH regulator.

[0066] The preparation method of the one-component reflective heat-insulating polyurethane waterproof coating in this example is the same as that of the coating in Example 2.

[0067] According to the regulations in the standards "Building Reflective Heat-Insulating Coatings" - JG / T 235-2014, "Emulsion Polymer Exterior Coatings" - GB / T 9755-2014, and "Waterborne Polyurethane Waterproof Coatings" - T / CWA 206-2021, the one-component reflective heat-insulating polyurethane waterproof coatings prepared in Examples 2 to 4 of the present invention were subjected to performance tests, and the various indicators are shown in the following table:

[0068]

[0069]

[0070] As can be seen from the above table, the one-component reflective heat-insulating polyurethane waterproof coatings prepared in Examples 2 to 4 of the present invention can all meet the basic performance requirements of conventional exterior walls. Among them, the one-component reflective heat-insulating polyurethane waterproof coating prepared in Example 2 has more excellent comprehensive performance and has a good effect of heat insulation and temperature reduction. The one-component reflective heat-insulating polyurethane waterproof coatings prepared in the three examples have excellent reflective heat-insulating performance for light waves. Among them, the solar reflectance, near-infrared reflectance, and hemispherical emissivity are all better than the technical indicators in the standard. After being applied to the outer surface of a building, most of the solar light and heat can be reflected away and will not accumulate on the outer surface of the building, so that the internal space of the object can maintain a persistent constant temperature state. When used in areas and seasons with strong sunlight, it can save air-conditioning power consumption. Different from previous similar products, it is not because of the small thermal conductivity coefficient of the material, but because the heat-reflective powder in the coating component is a high-whiteness near-infrared reflective silicate material. The crystal structure of this silicate material contains many pores and micro-spaces, which can hinder the processes of heat conduction and heat radiation, thereby playing a role in heat insulation. The existence of these pores and micro-spaces makes the thermal conductivity coefficient of the silicate very low. At the same time, it is difficult for the energy level transition of this silicate material, and it can absorb visible light and infrared rays of the sun. The combined action of these factors endows it with excellent heat-insulating performance, thus achieving the purpose of reducing temperature. In the hot summer, the sunlight irradiation will not cause the coating to heat up, and its surface is also cool.

[0071] The film formed after the one-component reflective heat-insulating polyurethane waterproof coating of the present invention is applied to the outer surface of a building is dense, has super weather resistance and high-elastic waterproof function, and can also play the role of a waterproof coating. In addition, it is a one-component coating, which is more convenient for preparation, transportation and use.

[0072] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A one-component reflective heat-insulating polyurethane waterproof coating, characterized in that: The invention comprises the following raw materials in parts by weight: Deionized water: 100-120 parts; Cellulose: 1.5-2.5 parts; pH regulator: 1-1.5 parts; Fungicide: 2-3 parts; Dispersant: 6-8 parts; Wetting agent: 1.5-2 parts; Defoaming agent: 2-5 parts; Film-forming aid: 15-20 parts; Titanium dioxide: 150-200 parts; Heat reflective powder: 250-350 parts; Barium sulfate: 100-150 parts; Water-based polyurethane emulsion: 380-450 parts; Leveling agent: 3-5 parts; Thickener: 1 to 1.5 parts.

2. The one-component reflective heat-insulating polyurethane waterproof coating according to claim 1, characterized in that: The aqueous polyurethane emulsion is an anionic aliphatic polyether polyurethane dispersion.

3. The one-component reflective heat-insulating polyurethane waterproof coating according to claim 1, characterized in that: The bactericide is 2-methyl-4-isothiazoline-3-one.

4. The one-component reflective heat-insulating polyurethane waterproof coating according to claim 1, characterized in that: The wetting agent is any one of polyoxyethylene alkylphenol ether, polyoxyethylene fatty alcohol ether, and polyoxyethylene polyoxypropylene block copolymer.

5. The one-component reflective heat-insulating polyurethane waterproof coating according to claim 1, characterized in that: The cellulose is hydroxyethyl cellulose.

6. The one-component reflective heat-insulating polyurethane waterproof coating according to claim 1, characterized in that: The pH value regulator is a mixture of 2-amino-2-methyl-1-propanol and water.

7. The one-component reflective heat-insulating polyurethane waterproof coating according to claim 1, characterized in that: The heat reflective powder is a high-whiteness near-infrared silicate reflective material, which is ground and crushed by a planetary grinder for 3 to 5 hours to form a 12000 to 13000 mesh powder, and a classifier is used to remove coarse particles to form a silicate solid powder with an average particle size of 1 μm.

8. The one-component reflective heat-insulating polyurethane waterproof coating according to claim 1, characterized in that: The dispersant is a polyacrylate ammonium salt dispersant; the titanium dioxide is a rutile titanium dioxide; and the film-forming aid is dipropylene glycol methyl ether.

9. The one-component reflective heat-insulating polyurethane waterproof coating according to claim 1, characterized in that: The defoamer is a mineral oil defoamer; the leveling agent is a polyurethane leveling agent; and the thickener is a polyurethane thickener.

10. A method for preparing a one-component reflective heat-insulating polyurethane waterproof coating, using the one-component reflective heat-insulating polyurethane waterproof coating according to any one of claims 1 to 9, characterized in that: The following steps are involved: Step 1: Weigh the raw material components according to the ratio of the single-component reflective heat-insulating polyurethane waterproof coating, add deionized water into the reaction tank, and stir at a speed of 400-500 rpm; Step 2: According to the proportion of raw material components, add cellulose, dispersant, fungicide, wetting agent and film-forming aid into water in sequence under stirring and mix evenly; then continue stirring at a speed of 400-500 rpm for 4-6 minutes; Step 3: Add heat reflective powder, titanium dioxide and barium sulfate to the mixture obtained in step 2 in sequence, mix well, and stir at a dispersion speed of 1200-1600 rpm for 12-18 minutes until the paint slurry is uniform; make the fineness of the obtained liquid ≦55um; Step 4: adding the waterborne polyurethane emulsion to the liquid obtained in step 3, mixing evenly, to obtain a paint slurry; Stir at 800-1000 rpm for 4-6 minutes. Step 5: Slowly add pH adjuster, defoamer, leveling agent and thickener to the reaction tank in step 4 for thickening, stir at a speed of 800-1000 rpm for 4-6 minutes, measure the initial viscosity, adjust the viscosity to 100-105KU, and prepare a single-component reflective heat-insulating polyurethane waterproof coating.

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