A solvent-free exposed polyurethane waterproof thermal insulation coating and a preparation method thereof

Abstract

The application provides a solvent-free exposed polyurethane waterproof thermal insulation coating and a preparation method thereof, and belongs to the technical field of waterproof coatings.The coating comprises the following raw material components: cashew nut shell oil modified polyol, polyacrylate polyol, oligomeric phosphate ester flame retardant, wetting dispersant, ultraviolet absorber, hindered amine light stabilizer, antioxidant, rutile titanium white, modified nano titanium dioxide, nano zinc oxide, ultra-fine ceramic microbead powder, octamethylene diisocyanate, stannous octoate, defoaming agent, bisaldimine, and 3-(2,3-epoxypropoxy) propyl triethoxysilane.The product does not contain organic solvents, has excellent weather resistance, has flame retardation and thermal insulation functions, and can be used in exposed use.

Description

Technical Field

[0001] This invention relates to the field of waterproof coating technology, and in particular to a solvent-free exposed polyurethane waterproof and heat-insulating coating and its preparation method. Background Technology

[0002] With the acceleration of urbanization, my country's urbanization rate reached 66.16% by the end of 2023, while that of developed countries is around 80%. The room for further expansion is gradually shrinking, and the future structure of my country's construction market will gradually transition from being dominated by new construction to a stage where new construction and renovation coexist. Waterproofing is a particularly prominent issue in the maintenance and repair of buildings. Due to aging building materials and improper construction, many buildings suffer from leaks and seepage in their roofs, walls, and basements.

[0003] Polyurethane waterproof coatings are characterized by high elasticity, good extensibility, strong adhesion, and adaptability to deformation caused by cracks in the substrate. They are also easy to apply to any complex substrate surface, making them a primary material for building waterproofing and widely used. Abroad, polyurethane waterproof coatings are also a common choice for new construction, renovation, and repair projects of exposed roofs, especially when there are many types of equipment and complex joints. However, many polyurethane waterproof coatings used for repairs on the market have poor weather resistance. With prolonged exposure, the surface will powder and crack, the coating will gradually thin, its physical properties will significantly decrease, and eventually the waterproof layer will lose its effectiveness. Furthermore, most polyurethane waterproof coatings contain organic solvents and are not flame-retardant, making them unsafe and environmentally unfriendly, and prone to causing poisoning and fire accidents. In addition, many factories are now built with steel structures. Because metal has high thermal conductivity, indoor temperatures become particularly high in summer. Therefore, many buildings have high requirements for the heat insulation effect of exposed waterproof coatings to reduce building energy consumption while preventing metal surfaces from rusting.

[0004] CN114395320B discloses a chemically resistant, exposed, single-component polyurethane waterproof coating and its preparation method. The coating, by weight, comprises 20-40 parts polyether, 5-20 parts plasticizer, 30-50 parts pigments and fillers, 0.3-2 parts weather-resistant additives, 0.1-0.5 parts pH adjuster, 1-5 parts desiccant, 1-5 parts dehydrating agent, 5-10 parts isocyanate, 0.15-2 parts catalyst, 5-10 parts alkane oil, 0.2-1 parts chain extender / crosslinker, and 0.6-3 parts solvent. This waterproof coating exhibits high strength, a dense film, and no sagging even after 24 hours of application to vertical surfaces (2mm thick coat). It is easy to apply and possesses excellent physical properties and weather resistance. It can be used for exposed applications, expanding the application scope of polyurethane waterproof coatings in the building waterproofing field. However, it uses organic solvents (alkane oil) and does not have heat insulation or flame retardant functions.

[0005] Therefore, developing an exposed polyurethane waterproof coating that is free of organic solvents, has excellent weather resistance, and possesses flame-retardant and heat-insulating functions has good market prospects and is of great significance. Summary of the Invention

[0006] To solve the above technical problems, the present invention provides a solvent-free exposed polyurethane waterproof and heat-insulating coating and its preparation method, and achieves the following objectives: the product does not contain organic solvents, has excellent weather resistance, and has flame-retardant and heat-insulating functions, and can be used in the open.

[0007] To achieve the above-mentioned objectives, the technical solution adopted is as follows:

[0008] A solvent-free, exposed polyurethane waterproof and heat-insulating coating, comprising, by weight:

[0009] Cashew shell oil modified polyol 25-50 parts, polyacrylate polyol 10-40 parts, oligophosphate flame retardant 5-15 parts, wetting and dispersing agent 0.3-0.5 parts, ultraviolet absorber 0.3-0.7 parts, hindered amine light stabilizer 0.3-0.7 parts, antioxidant 0.2-0.5 parts, rutile titanium dioxide 5-10 parts, modified nano titanium dioxide 3-6 parts, nano zinc oxide 3-5 parts, ultrafine ceramic microsphere powder 3-5 parts, octamethylene diisocyanate 4-9 parts, stannous octoate 0.1-0.3 parts, defoamer 0.3-0.5 parts, dialdehyde imine 1-3 parts, 3-(2,3-epoxypropoxy)propyltriethoxysilane 1-3 parts.

[0010] The solvent-free exposed polyurethane waterproof and heat-insulating coating is a single component, contains no organic solvents, and has excellent weather resistance, flame retardancy, and heat insulation properties.

[0011] The cashew nut shell oil-modified polyol has a hydroxyl value of 250~260 mgKOH / g and a viscosity of 1000~1300 mpa.s.

[0012] The polyacrylate polyol is a high-solids polyacrylate polyol with a hydroxyl value of 75~85 mgKOH / g and a viscosity of 1200~1800 mpa.s.

[0013] The aforementioned polyphosphate flame retardant is an ethyl ethyl phosphate oligomer with a phosphorus content of 18-20%, a hydroxyl value of 2-5 mgKOH / g, and a viscosity of 2100-2300 mpa.s.

[0014] The wetting and dispersing agent is a modified polyorganic carboxylic acid ammonium salt with a solid content >96% and an ammonia value of 20~30 mgKOH / g.

[0015] The ultraviolet absorber is a liquid benzotriazole ultraviolet absorber.

[0016] The hindered amine light stabilizer is a liquid hindered amine light stabilizer.

[0017] The antioxidant mentioned is a liquid hindered phenolic antioxidant.

[0018] The modified nano-titanium dioxide is prepared by reacting an aqueous dispersion of nano-titanium dioxide with an ethanol solution of the surface modifier, followed by filtration and drying.

[0019] The defoamer is a strong silicone defoamer containing defoaming particles, suitable for solvent-free systems, with a solid content ≥90%.

[0020] A method for preparing a solvent-free, exposed polyurethane waterproof and heat-insulating coating, comprising the following steps:

[0021] Cashew nut shell oil-modified polyol, polyacrylate polyol, oligophosphate flame retardant, wetting and dispersing agent, ultraviolet absorber, hindered amine light stabilizer, and antioxidant were added to the reactor. The temperature was raised to 100±2℃, and after stirring evenly, rutile titanium dioxide, modified nano titanium dioxide, nano zinc oxide, and ultrafine ceramic microsphere powder were added in sequence. The temperature was then raised to 105±2℃, and the mixture was circulated and ground in a colloid mill for 1 hour. The temperature was then raised to 115±2℃, and the mixture was dehydrated under a vacuum of -0.095~-0.1MPa for 3.5 hours, during which nitrogen gas was introduced to replace the water 4 times. The extract in the vacuum buffer tank was collected.

[0022] When the central moisture content is <0.1‰, the temperature is lowered to 60±2℃, nitrogen gas is introduced, octamethylene diisocyanate is added, and then the temperature is slowly raised to 80±2℃. The mixture is stirred at a constant temperature for 2.5 hours. After cooling to 70~75℃, stannous octoate is added, and high-speed dispersion is started. After 30 minutes, defoamer, dialdehyde imine, and 3-(2,3-epoxypropoxy)propyltriethoxysilane are added. The mixture is stirred for 15 minutes, and then the nitrogen gas is turned off. The mixture is then degassed under vacuum for 15 minutes and discharged to obtain a solvent-free exposed polyurethane waterproof and heat-insulating coating.

[0023] The above technical solutions have the following beneficial effects:

[0024] The solvent-free exposed polyurethane waterproof and heat-insulating coating produced by the method of this invention has flame-retardant and heat-insulating properties; it contains no organic solvents, effectively solving the environmental protection and safety problems of ordinary polyurethane products; it does not use plasticizers, so the material performance is stable and reliable, with no migration, and the coating does not chalk or crack during long-term exposed use; it has excellent adhesion properties, which can meet the needs of various substrates, especially metal substrates; the coating has thixotropic properties, resulting in a better feel during construction; it has good heat insulation properties, effectively reflects sunlight, and can help buildings reduce energy consumption in summer, making it green and low-carbon.

[0025] The solvent-free exposed polyurethane waterproof and heat-insulating coating prepared by the method of this invention has the following properties: tensile strength above 5.2 MPa, elongation at break above 670%, tear strength above 27 N / mm, solid content reaching 99%, low-temperature bending performance reaching -40℃ without cracks, water impermeability reaching (0.4 MPa, 120 min) water impermeability, bonding strength above 2.6 MPa, flammability rating of B1-C, solar reflectance (white) above 0.83, and meets the requirements of artificial climate aging (2745h). Detailed Implementation

[0026] For ease of explanation, a solvent-free, exposed polyurethane waterproof and heat-insulating coating and its preparation method are described in detail.

[0027] Example 1: A solvent-free, exposed polyurethane waterproof and heat-insulating coating and its preparation method

[0028] A solvent-free, exposed polyurethane waterproof and heat-insulating coating, with the following raw material components by weight:

[0029] The composition includes: 35 parts cashew nut shell oil modified polyol, 12 parts polyacrylate polyol, 9 parts oligophosphate flame retardant, 0.4 parts wetting and dispersing agent, 0.5 parts ultraviolet absorber, 0.4 parts hindered amine light stabilizer, 0.3 parts antioxidant, 6 parts rutile titanium dioxide, 5 parts modified nano titanium dioxide, 4 parts nano zinc oxide, 3 parts ultrafine ceramic microsphere powder, 5 parts octamethylene diisocyanate, 0.1 parts stannous octoate, 0.3 parts defoamer, 2 parts dialdehyde imine, and 1.5 parts 3-(2,3-epoxypropoxy)propyltriethoxysilane.

[0030] The aforementioned polyphosphate flame retardant is an ethyl ethyl phosphate oligomer;

[0031] The wetting and dispersing agent is a modified polyorganic carboxylic acid ammonium salt;

[0032] The ultraviolet absorber is a liquid benzotriazole ultraviolet absorber, model number Tinuvin 571;

[0033] The hindered amine light stabilizer is a liquid hindered amine light stabilizer, model number Tinuvin 765;

[0034] The antioxidant mentioned is a liquid hindered phenolic antioxidant, model Irganox 1135;

[0035] The defoamer is an organosilicone defoamer.

[0036] A method for preparing a solvent-free, exposed polyurethane waterproof and heat-insulating coating, comprising the following steps:

[0037] Cashew nut shell oil-modified polyol, polyacrylate polyol, oligophosphate flame retardant, wetting and dispersing agent, ultraviolet absorber, hindered amine light stabilizer, and antioxidant were added to the reactor. The temperature was raised to 100°C, and after stirring evenly, rutile titanium dioxide, modified nano titanium dioxide, nano zinc oxide, and ultrafine ceramic microspheres were added in sequence. The temperature was then raised to 105°C, and the mixture was circulated and ground in a colloid mill for 1 hour. The temperature was then raised to 115°C, and the mixture was dehydrated under a vacuum of -0.095 MPa for 3.5 hours, during which nitrogen gas was introduced to replace the water 4 times. The extract in the vacuum buffer tank was collected.

[0038] When the central moisture content is <0.1‰, the temperature is lowered to 60℃, nitrogen gas is introduced, octamethylene diisocyanate is added, and then the temperature is slowly raised to 80℃ and stirred at a constant temperature for 2.5h. After cooling to 70℃, stannous octoate is added, high-speed dispersion is started, and after 30min, defoamer, dialdehyde imine, and 3-(2,3-epoxypropoxy)propyltriethoxysilane are added. After stirring for 15min, the nitrogen gas is turned off, and vacuum degassing is performed for 15min. The material is then discharged to obtain a solvent-free exposed polyurethane waterproof and heat-insulating coating.

[0039] Example 2: A solvent-free, exposed polyurethane waterproof and heat-insulating coating and its preparation method

[0040] A solvent-free, exposed polyurethane waterproof and heat-insulating coating, with the following raw material components by weight:

[0041] The ingredients are: 25 parts cashew nut shell oil modified polyol, 10 parts polyacrylate polyol, 5 parts oligophosphate flame retardant, 0.3 parts wetting and dispersing agent, 0.3 parts ultraviolet absorber, 0.3 parts hindered amine light stabilizer, 0.2 parts antioxidant, 5 parts rutile titanium dioxide, 3 parts modified nano titanium dioxide, 3 parts nano zinc oxide, 3 parts ultrafine ceramic microsphere powder, 4 parts octamethylene diisocyanate, 0.1 parts stannous octoate, 0.3 parts defoamer, 1 part dialdehyde imine, and 1 part 3-(2,3-epoxypropoxy)propyltriethoxysilane.

[0042] The aforementioned polyphosphate flame retardant is an ethyl ethyl phosphate oligomer;

[0043] The wetting and dispersing agent is a modified polyorganic carboxylic acid ammonium salt;

[0044] The ultraviolet absorber is a liquid benzotriazole ultraviolet absorber, model number Tinuvin 1130;

[0045] The hindered amine light stabilizer is a liquid hindered amine light stabilizer, model number Tinuvin 765;

[0046] The antioxidant mentioned is a liquid hindered phenolic antioxidant, model Irganox 1135;

[0047] The defoamer is an organosilicone defoamer.

[0048] A method for preparing a solvent-free, exposed polyurethane waterproof and heat-insulating coating, comprising the following steps:

[0049] Cashew nut shell oil-modified polyol, polyacrylate polyol, oligophosphate flame retardant, wetting and dispersing agent, ultraviolet absorber, hindered amine light stabilizer, and antioxidant were added to the reactor. The temperature was raised to 98°C, and after stirring evenly, rutile titanium dioxide, modified nano titanium dioxide, nano zinc oxide, and ultrafine ceramic microsphere powder were added in sequence. The temperature was then raised to 103°C, and the mixture was circulated and ground in a colloid mill for 1 hour. The temperature was then raised to 117°C, and the mixture was dehydrated under a vacuum of -0.095 MPa for 3.5 hours, during which nitrogen gas was introduced to replace the water 4 times. The extract in the vacuum buffer tank was collected.

[0050] When the central moisture content is <0.1‰, the temperature is lowered to 58℃, nitrogen gas is introduced, octamethylene diisocyanate is added, and then the temperature is slowly raised to 82℃. The mixture is stirred at a constant temperature for 2.5 hours. After cooling to 75℃, stannous octoate is added, and high-speed dispersion is started. After 30 minutes, defoamer, dialdehyde imine, and 3-(2,3-epoxypropoxy)propyltriethoxysilane are added. The mixture is stirred for 15 minutes, and then the nitrogen gas is turned off. The mixture is then degassed under vacuum for 15 minutes and discharged to obtain a solvent-free exposed polyurethane waterproof and heat-insulating coating.

[0051] Example 3: A solvent-free, exposed polyurethane waterproof and heat-insulating coating and its preparation method

[0052] A solvent-free, exposed polyurethane waterproof and heat-insulating coating, with the following raw material components by weight:

[0053] Cashew shell oil modified polyol 50 parts, polyacrylate polyol 40 parts, oligophosphate flame retardant 15 parts, wetting and dispersing agent 0.5 parts, ultraviolet absorber 0.7 parts, hindered amine light stabilizer 0.7 parts, antioxidant 0.5 parts, rutile titanium dioxide 10 parts, modified nano titanium dioxide 6 parts, nano zinc oxide 5 parts, ultrafine ceramic microsphere powder 5 parts, octamethylene diisocyanate 9 parts, stannous octoate 0.3 parts, defoamer 0.5 parts, dialdehyde imine 3 parts, 3-(2,3-epoxypropoxy)propyltriethoxysilane 3 parts.

[0054] The aforementioned polyphosphate flame retardant is an ethyl ethyl phosphate oligomer;

[0055] The wetting and dispersing agent is a modified polyorganic carboxylic acid ammonium salt;

[0056] The ultraviolet absorber is a liquid benzotriazole ultraviolet absorber, model number Tinuvin 571;

[0057] The hindered amine light stabilizer is a liquid hindered amine light stabilizer, model number Tinuvin 765;

[0058] The antioxidant mentioned is a liquid hindered phenolic antioxidant, model Irganox 1135;

[0059] The defoamer is an organosilicone defoamer.

[0060] A method for preparing a solvent-free, exposed polyurethane waterproof and heat-insulating coating, comprising the following steps:

[0061] Cashew nut shell oil-modified polyol, polyacrylate polyol, oligophosphate flame retardant, wetting and dispersing agent, ultraviolet absorber, hindered amine light stabilizer, and antioxidant were added to the reactor. The temperature was raised to 102°C, and after stirring evenly, rutile titanium dioxide, modified nano titanium dioxide, nano zinc oxide, and ultrafine ceramic microsphere powder were added in sequence. The temperature was then raised to 107°C, and the mixture was circulated and ground in a colloid mill for 1 hour. The temperature was then raised to 113°C, and the mixture was dehydrated under a vacuum of -0.1 MPa for 3.5 hours, during which nitrogen gas was introduced to replace the water 4 times. The extract in the vacuum buffer tank was collected.

[0062] When the central moisture content is <0.1‰, the temperature is lowered to 62℃, nitrogen gas is introduced, octamethylene diisocyanate is added, and then the temperature is slowly raised to 78℃. The mixture is stirred at a constant temperature for 2.5 hours. After cooling to 70℃, stannous octoate is added, and high-speed dispersion is started. After 30 minutes, defoamer, dialdehyde imine, and 3-(2,3-epoxypropoxy)propyltriethoxysilane are added. The mixture is stirred for 15 minutes, and then the nitrogen gas is turned off. The mixture is then degassed under vacuum for 15 minutes and discharged to obtain a solvent-free exposed polyurethane waterproof and heat-insulating coating.

[0063] Example 4: A solvent-free, exposed polyurethane waterproof and heat-insulating coating and its preparation method

[0064] A solvent-free exposed polyurethane waterproof and heat-insulating coating is prepared by comparing it with Example 1, under the same conditions as Example 1, only changing the amount of polyphosphate flame retardant. In Example 4, 20 parts of polyphosphate flame retardant are used, and the weight parts of other components are not changed. The coating is prepared according to the preparation method of solvent-free exposed polyurethane waterproof and heat-insulating coating described in Example 1.

[0065] Example 5: A solvent-free, exposed polyurethane waterproof and heat-insulating coating and its preparation method

[0066] A solvent-free exposed polyurethane waterproof and heat-insulating coating is prepared by comparing it with Example 1, under the same conditions as Example 1, only the amount of modified nano-titanium dioxide is changed. In Example 5, 0.5 parts of modified nano-titanium dioxide are used, and the weight parts of other components are not changed. The coating is prepared according to the preparation method of solvent-free exposed polyurethane waterproof and heat-insulating coating described in Example 1.

[0067] The solvent-free, exposed polyurethane waterproof and heat-insulating coatings prepared according to the above five embodiments were subjected to performance testing. The test results are shown in Table 1.

[0068] Table 1

[0069]

[0070] As shown in Table 1, the solvent-exposed polyurethane waterproof and heat-insulating coatings prepared in Examples 1-3 of this invention have excellent mechanical properties, low-temperature resistance, water impermeability, flame retardancy, heat insulation properties, and anti-aging properties.

[0071] The coating prepared in Example 4 has a low polyurethane viscosity, which makes it prone to flowing when applied to vertical or sloping surfaces, thus failing to meet the requirements.

[0072] The coating prepared in Example 5 began to sag when the coating thickness reached 0.6 mm. At the same time, the solar reflectance was relatively low, and the performance degraded significantly after artificial climate aging treatment, failing to meet the requirements.

[0073] In embodiments of the present invention:

[0074] The cashew nut shell oil-modified polyol has a hydroxyl value of 250-260 mgKOH / g and a viscosity of 1000-1300 mPa·s.

[0075] The polyacrylate polyol has a hydroxyl value of 75~85 mgKOH / g and a viscosity of 1200~1800 mpa.s.

[0076] The ethyl ethylidene phosphate oligomer has a phosphorus content of 18-20%, a hydroxyl value of 2-5 mgKOH / g, and a viscosity of 2100-2300 mpa.s.

[0077] The modified polyorganic carboxylic acid ammonium salt has a solid content >96% and an ammonia value of 20~30 mgKOH / g.

[0078] The rutile titanium dioxide has a TiO2 content of ≥94% and a refractive index greater than 2.7.

[0079] The modified nano-titanium dioxide is prepared by reacting an aqueous dispersion of nano-titanium dioxide with an ethanol solution of the surface modifier, followed by filtration and drying. The resulting modified nano-titanium dioxide has an average particle size of 30±5 nm and a specific surface area of ​​70±10 m². 2 / g.

[0080] The nano-zinc oxide has a purity of ≥99.8%, an average particle size of 30~50nm, and a specific surface area of ​​20~40m². 2 / g.

[0081] The ultrafine ceramic microsphere powder has a particle size of 1200~1500 mesh and a thermal conductivity of <0.1 W / m / ℃.

[0082] The octamethylene diisocyanate has a density of 1.007 g / ml and a boiling point of 156 °C.

[0083] The dialdehyde imine has a functionality of 2 and an equivalent (g / eq isocyanate) of 125.

[0084] The organosilicon strong defoamer contains defoaming particles, is suitable for solvent-free systems, and has a solid content of ≥90%.

[0085] It should be noted that, unless otherwise stated, the proportions of the ingredients in this invention are calculated in parts by weight.

[0086] The preferred embodiments of the present invention have been described in the above examples. It is obvious that many variations can be made within the inventive concept of the present invention. It should be noted that any changes made within the inventive concept of the present invention will fall within the protection scope of the present invention.

Claims

1. A solvent-free, exposed polyurethane waterproof and heat-insulating coating, characterized in that: The raw material components include: cashew nut shell oil modified polyol, polyacrylate polyol, polyphosphate flame retardant, wetting and dispersing agent, ultraviolet absorber, hindered amine light stabilizer, antioxidant, rutile titanium dioxide, modified nano titanium dioxide, nano zinc oxide, ultrafine ceramic microsphere powder, octamethylene diisocyanate, stannous octoate, defoamer, dialdehyde imine, and 3-(2,3-epoxypropoxy)propyltriethoxysilane; The weight ratio of the raw material components is as follows: 25-50 parts of cashew nut shell oil modified polyol, 10-40 parts of polyacrylate polyol, 5-15 parts of oligophosphate flame retardant, 0.3-0.5 parts of wetting and dispersing agent, 0.3-0.7 parts of ultraviolet absorber, 0.3-0.7 parts of hindered amine light stabilizer, 0.2-0.5 parts of antioxidant, 5-10 parts of rutile titanium dioxide, 3-6 parts of modified nano titanium dioxide, 3-5 parts of nano zinc oxide, 3-5 parts of ultrafine ceramic microsphere powder, 4-9 parts of octamethylene diisocyanate, 0.1-0.3 parts of stannous octoate, 0.3-0.5 parts of defoamer, 1-3 parts of dialdehyde imine, and 1-3 parts of 3-(2,3-epoxypropoxy)propyltriethoxysilane. The solvent-free exposed polyurethane waterproof and heat-insulating coating is a single component and does not contain organic solvents; The modified nano-titanium dioxide described herein uses alkoxytris(vinyl-ethoxy)zirconate as the surface modifier. The cashew nut shell oil modified polyol has a hydroxyl value of 250-260 mg KOH / g and a viscosity of 1000-1300 mPa·s; the polyacrylate polyol has a hydroxyl value of 75-85 mg KOH / g and a viscosity of 1200-1800 mPa·s.

2. The solvent-free exposed polyurethane waterproof and heat-insulating coating according to claim 1, characterized in that: The aforementioned polyphosphate flame retardant is an ethyl ethyl phosphate oligomer.

3. The solvent-free exposed polyurethane waterproof and heat-insulating coating according to claim 1, characterized in that: The wetting and dispersing agent is a modified polyorganic carboxylic acid ammonium salt.

4. The solvent-free exposed polyurethane waterproof and heat-insulating coating according to claim 1, characterized in that: The ultraviolet absorber is a liquid benzotriazole ultraviolet absorber; the antioxidant is a liquid hindered phenol antioxidant.

5. The method for preparing a solvent-free, exposed polyurethane waterproof and heat-insulating coating according to claim 1, characterized in that: The preparation method includes the following steps: Add cashew nut shell oil-modified polyol, polyacrylate polyol, oligophosphate flame retardant, wetting and dispersing agent, ultraviolet absorber, hindered amine light stabilizer, and antioxidant to the reactor. Heat to 100±2℃ and stir evenly. Then, add rutile titanium dioxide, modified nano titanium dioxide, nano zinc oxide, and ultrafine ceramic microspheres in sequence. Then, heat to 105±2℃ and circulate and grind in a colloid mill. Then, heat to 115±2℃ and dehydrate under vacuum. Cool to 60±2℃, introduce nitrogen gas, add octamethylene diisocyanate, then heat to 80±2℃ and stir at a constant temperature for 2±0.5℃. Cool to 70~75℃, add stannous octoate, disperse, add defoamer, dialdehyde imine, and 3-(2,3-epoxypropoxy)propyltriethoxysilane, stir, turn off the nitrogen gas, and defoam under vacuum.

6. The method for preparing a solvent-free, exposed polyurethane waterproof and heat-insulating coating according to claim 5, characterized in that: The vacuum dehydration process involves dehydrating under a vacuum of -0.095 to -0.1 MPa for 3 to 4 hours, during which nitrogen is introduced to replace the water 4 times, until the moisture content detected at the central control point is <0.1‰.

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