Aqueous thermal barrier coating and method of making the same

Abstract

The present application relates to the technical field of paint, in particular to a kind of water-based heat insulation paint and preparation method thereof.The paint includes modified styrene-acrylic emulsion, dispersant, wetting agent, thickening agent and defoaming agent.Modified styrene-acrylic emulsion is prepared by synergistic polymerization of styrene, acrylic monomer, octaphenyl cage polysilsesquioxane and alkenyl silicon-based aerogel, can form uniform and stable multi-level heat insulation structure, efficiently block heat conduction path, and enhance the mechanical properties and thermal stability of coating.In the process, by reasonable time sequence of component addition and "hard core-soft shell" gradient structure design, performance optimization is realized.The paint has excellent heat insulation, weather resistance, temperature change resistance, is easy to operate, environment-friendly and non-toxic, can significantly reduce building surface temperature, reduce energy consumption, prolong building life, help to alleviate urban heat island effect, meet the development trend of green building, provide an efficient and environment-friendly heat insulation technical solution.

Description

Technical Field

[0001] The present invention relates to the technical field of coatings, and in particular to a water-based thermal insulation coating and a preparation method thereof. Background Art

[0002] With the continued growth of global energy demand and the increasing improvement of energy conservation and emission reduction policies, the issue of building energy consumption has gradually become a hot topic of social concern. Among them, exterior wall thermal insulation coatings have attracted increasing research and development attention due to their significant role in improving the thermal performance of buildings and reducing cooling and heating energy consumption. As a green and environmentally friendly building material, water-based thermal insulation coatings have been widely used in the field of building exterior walls due to their low VOC emissions, easy construction and excellent thermal insulation properties. However, existing water-based thermal insulation coatings still have many shortcomings in terms of performance, especially in the optimization of the coating's thermal insulation, durability and comprehensive mechanical properties.

[0003] Existing water-based thermal insulation coatings typically achieve their insulation effects by adding hollow structural materials (such as hollow glass microspheres or silica-based aerogels) and highly reflective pigments and fillers (such as titanium dioxide). The hollow structural materials reduce heat conduction by creating a multi-level insulation pathway while scattering infrared radiation through their highly reflective surface. However, these traditional insulation methods present two major challenges. First, inorganic materials like hollow microspheres have poor dispersion within the coating matrix and are prone to agglomeration, resulting in an inability to form a uniform insulation barrier, significantly reducing insulation performance. Second, the weak bonding between the inorganic materials and the organic polymer matrix leads to insufficient interfacial stability, making them prone to delamination or cracking over long-term use, severely impairing the coating's resistance to aging and temperature fluctuations. Furthermore, traditional thermal insulation coatings exhibit low physical and chemical stability in extreme environments (such as UV exposure, high temperature and humidity, and rapid temperature fluctuations), making them difficult to withstand long-term use. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to propose a water-based thermal insulation coating and a preparation method thereof, so as to solve the problems of uneven dispersion and poor stability of nanomaterials in existing water-based thermal insulation coatings, which in turn lead to insufficient thermal insulation and durability.

[0005] Based on the above purpose, the present invention provides a water-based thermal insulation coating, which includes the following components, by weight: 80-120 parts of modified styrene-acrylic emulsion, 0.3-1 parts of dispersant, 2-4 parts of wetting agent, 0.3-0.8 parts of thickener and 0.1-0.5 parts of defoaming agent.

[0006] Preferably, the dispersant is sodium polycarboxylate; the wetting agent is ethylene glycol butyl ether; the thickener is hydroxyethyl cellulose; and the defoaming agent is a silicone defoaming agent.

[0007] Furthermore, the preparation steps of the modified styrene-acrylic emulsion are as follows:

[0008] S1: mixing an emulsifier and deionized water to obtain an emulsifier solution; mixing styrene, butyl acrylate, and isooctyl acrylate to obtain a monomer mixture A; mixing acrylic acid, styrene, butyl acrylate, and isooctyl acrylate to obtain a monomer mixture B; and mixing ammonium persulfate, sodium bicarbonate, and deionized water to obtain an initiator solution;

[0009] S2: Add monomer mixture A, octaphenyl cage polysilsesquioxane and olefinic silicon-based aerogel to the emulsifier solution, stir for 20-40 minutes, then heat to 83-87°C, add initiator solution dropwise, stir for 3.5-4.5 hours after the addition is complete, then add monomer mixture B and initiator solution dropwise, stir for 3.5-4.5 hours after the addition is complete, finally, cool to room temperature, add ammonia water to adjust the pH to 7.9-8.3, and obtain a modified styrene-acrylic emulsion.

[0010] Preferably, the emulsifier in step S1 is a mixture of Span 80 and Tween 80 in a weight ratio of 10-15:6-10.

[0011] Preferably, the weight ratio of the emulsifier to deionized water in the emulsifier solution of step S1 is 16-25:80-120.

[0012] Preferably, the weight ratio of styrene, butyl acrylate and isooctyl acrylate in the monomer mixture A of step S1 is 30-50:3-5:3-5.

[0013] Preferably, the weight ratio of acrylic acid, styrene, butyl acrylate and isooctyl acrylate in the monomer mixture B of step S1 is 1.5-2.5:15-25:8-12:15-25.

[0014] Preferably, the weight ratio of ammonium persulfate, sodium bicarbonate and deionized water in the initiator solution of step S1 is 0.25-0.35:0.2-0.3:25-35.

[0015] Preferably, in step S2, the weight ratio of monomer mixture A, octaphenyl cage polysilsesquioxane, olefinic silicon-based aerogel, emulsifier solution, initiator solution and monomer mixture B is 36-60:8-12:15-25:95-145:25-35:39.5-64.5.

[0016] Preferably, in step S2, the weight ratio of the first dropwise addition of the initiator solution to the second dropwise addition of the initiator solution is 8-12:17-23.

[0017] Preferably, the olefinated silicon-based aerogel in step S2 is obtained by modifying silicon-based aerogel with vinyltrimethoxysilane; and the weight ratio of vinyltrimethoxysilane to silicon-based aerogel is 0.3-0.8:15-25.

[0018] Preferably, the average particle size of the silicon-based aerogel is 10-20 μm, and the specific surface area is 500-800 m 2 / g.

[0019] Furthermore, the present invention also provides a method for preparing a water-based thermal insulation coating, comprising the following steps: stirring the modified styrene-acrylic emulsion, dispersant, and wetting agent at a speed of 1000-1500 rpm for 10-20 minutes, then adding a thickener and a defoaming agent, and continuing to stir at a speed of 1000-1500 rpm for 10-20 minutes to obtain a water-based thermal insulation coating.

[0020] Beneficial effects of the present invention:

[0021] The water-based thermal insulation coating provided by this invention offers multiple significant advantages. First, it utilizes olefinic silicon-based aerogel as a key functional component. The surface vinyl functional groups form a chemical bond with the styrene-acrylate copolymer, significantly enhancing the dispersion and interfacial bonding of the microspheres within the polymer matrix. This creates a stable and uniform multi-level thermal insulation structure, effectively blocking heat conduction paths.

[0022] Secondly, the invention cleverly incorporates octaphenyl cage-type polysilsesquioxane. Its unique rigid cage structure and phenyl functional groups form a dynamic physical crosslinking network through steric hindrance and π-π interactions, significantly enhancing the thermal stability and structural integrity of the coating. This nanoscale reinforcement mechanism enables the coating to achieve excellent weathering and temperature resistance while maintaining its lightweight properties.

[0023] The innovative process design employed in this invention is also key to its performance advantages. By precisely controlling the timing of the addition of the functional components, particularly the early and simultaneous addition of the octaphenyl cage-type polysilsesquioxane and the hard monomer mixture, the formation of a synergistic network between the nanocomponents is promoted. Furthermore, the process sequence of polymerizing the hard monomer first and adding the soft monomer later creates a "hard core-soft shell" gradient structure, optimizing the stress distribution mechanism and achieving a perfect balance between coating rigidity and elasticity.

[0024] This structural design and process innovation enable the water-based thermal insulation coating of this invention to perform exceptionally well in practical applications, significantly reducing building surface temperatures, reducing energy consumption, and extending building service life. The coating is easy to apply, environmentally friendly, and non-toxic, aligning with the development trend of green buildings. It also has a positive impact on mitigating the urban heat island effect, providing a highly efficient, durable, and environmentally friendly technical solution for building energy conservation. DETAILED DESCRIPTION

[0025] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to specific embodiments.

[0026] The silicon-based aerogel in the specific embodiment of the present invention was purchased from Zhongge Technology, model AG-DC15, with an average particle size of 15 μm and a specific surface area of ​​600 m 2 / g. Example

[0027] (1) 15 g of silica aerogel, 200 g of anhydrous ethanol and 0.3 g of vinyltrimethoxysilane were added to 300 g of deionized water, stirred and refluxed at 78 °C for 2 h, centrifuged, washed with anhydrous ethanol three times, and vacuum dried to obtain olefinated silica aerogel;

[0028] (2) Add 10 g of Span 80 and 6 g of Tween 80 to 80 g of deionized water and stir at 250 rpm for 25 min to obtain an emulsifier solution; mix 30 g of styrene, 3 g of butyl acrylate and 3 g of isooctyl acrylate to obtain a monomer mixture A; mix 1.5 g of acrylic acid, 15 g of styrene, 8 g of butyl acrylate and 15 g of isooctyl acrylate to obtain a monomer mixture B; mix 0.25 g of ammonium persulfate, 0.2 g of sodium bicarbonate and 25 g of deionized water to obtain an initiator solution;

[0029] (3) 36 g of monomer mixture A, 8 g of octaphenyl cage-type polysilsesquioxane and 15 g of olefinic silicon-based aerogel were added to 95 g of emulsifier solution, stirred at 250 rpm for 20 min, then heated to 83 °C, 8 g of initiator solution was added dropwise, and after the addition was complete, stirring was continued at 250 rpm for 3.5 h. 39.5 g of monomer mixture B and 17 g of initiator solution were then added dropwise, and after the addition was complete, stirring was continued at 250 rpm for 3.5 h. Finally, the temperature was cooled to room temperature, and ammonia water (concentration of 28 wt%) was added to adjust the pH to 7.9 to obtain a modified styrene-acrylic emulsion.

[0030] (4) 80 g of modified styrene-acrylic emulsion, 0.6 g of dispersant (sodium salt of polycarboxylate, model number NOPCO SN-Dispersant 5040), and 2 g of wetting agent (ethylene glycol butyl ether) were stirred at a speed of 1000 rpm for 10 min, and then 0.3 g of thickener (hydroxyethyl cellulose, model number Natrosol 250MBR) and 0.1 g of defoamer (organic silicone defoamer, model number BYK-035) were added, and the mixture was stirred at a speed of 1000 rpm for 10 min to obtain a water-based thermal insulation coating. Example

[0031] (1) 20 g of silica-based aerogel, 250 g of anhydrous ethanol and 0.5 g of vinyltrimethoxysilane were added to 350 g of deionized water, stirred and refluxed at 80 °C for 3 h, centrifuged, washed with anhydrous ethanol three times, and vacuum dried to obtain olefinated silica-based aerogel;

[0032] (2) Add 12 g of Span 80 and 8 g of Tween 80 to 100 g of deionized water and stir at 300 rpm for 30 min to obtain an emulsifier solution; mix 40 g of styrene, 4 g of butyl acrylate and 4 g of isooctyl acrylate to obtain a monomer mixture A; mix 2 g of acrylic acid, 20 g of styrene, 10 g of butyl acrylate and 20 g of isooctyl acrylate to obtain a monomer mixture B; mix 0.3 g of ammonium persulfate, 0.25 g of sodium bicarbonate and 30 g of deionized water to obtain an initiator solution;

[0033] (3) 48 g of monomer mixture A, 10 g of octaphenyl cage-type polysilsesquioxane and 20 g of olefinic silicon-based aerogel were added to 120 g of emulsifier solution, stirred at 300 rpm for 30 min, then heated to 85 °C, 10 g of initiator solution was added dropwise, and after the addition was completed, stirring was continued at 300 rpm for 4 h. Then 52 g of monomer mixture B and 20 g of initiator solution were added dropwise, and after the addition was completed, stirring was continued at 300 rpm for 4 h. Finally, the temperature was cooled to room temperature, and ammonia water (concentration of 28 wt%) was added to adjust the pH to 8 to obtain a modified styrene-acrylic emulsion.

[0034] (4) 100 g of modified styrene-acrylic emulsion, 0.8 g of dispersant (sodium salt of polycarboxylate, model number NOPCO SN-Dispersant 5040), and 3 g of wetting agent (ethylene glycol butyl ether) were stirred at a speed of 1200 rpm for 15 min, and then 0.5 g of thickener (hydroxyethyl cellulose, model number Natrosol 250MBR) and 0.3 g of defoamer (organic silicone defoamer, model number BYK-035) were added and stirred at a speed of 1200 rpm for 15 min to obtain a water-based thermal insulation coating. Example

[0035] (1) 25 g of silica-based aerogel, 300 g of anhydrous ethanol and 0.8 g of vinyltrimethoxysilane were added to 400 g of deionized water, refluxed and stirred at 82 °C for 4 h, centrifuged, washed with anhydrous ethanol three times, and vacuum dried to obtain olefinated silica-based aerogel;

[0036] (2) Add 115 g of Span 80 and 10 g of Tween 80 to 120 g of deionized water and stir at 350 rpm for 35 min to obtain an emulsifier solution; mix 50 g of styrene, 5 g of butyl acrylate and 5 g of isooctyl acrylate to obtain a monomer mixture A; mix 2.5 g of acrylic acid, 25 g of styrene, 12 g of butyl acrylate and 25 g of isooctyl acrylate to obtain a monomer mixture B; mix 0.35 g of ammonium persulfate, 0.3 g of sodium bicarbonate and 35 g of deionized water to obtain an initiator solution;

[0037] (3) 60 g of monomer mixture A, 12 g of octaphenyl cage-type polysilsesquioxane and 25 g of olefinic silicon-based aerogel were added to 145 g of emulsifier solution, stirred at 350 rpm for 40 min, then heated to 87 °C, 12 g of initiator solution was added dropwise, and after the addition was complete, stirring was continued at 350 rpm for 4.5 h, 64.5 g of monomer mixture B and 23 g of initiator solution were added dropwise, and after the addition was complete, stirring was continued at 350 rpm for 4.5 h, finally, the mixture was cooled to room temperature, and ammonia water (concentration of 28 wt%) was added to adjust the pH to 8.3 to obtain a modified styrene-acrylic emulsion;

[0038] (4) 120 g of modified styrene-acrylic emulsion, 1 g of dispersant (sodium salt of polycarboxylate, model number NOPCO SN-Dispersant 5040), and 4 g of wetting agent (ethylene glycol butyl ether) were stirred at a speed of 1500 rpm for 20 min, and then 0.8 g of thickener (hydroxyethyl cellulose, model number Natrosol 250MBR) and 0.5 g of defoamer (organic silicone defoamer, model number BYK-035) were added and stirred at a speed of 1500 rpm for 20 min to obtain a water-based thermal insulation coating.

[0039] Comparative Example 1:

[0040] The difference between Comparative Example 1 and Example 2 is that the olefinated silicon-based aerogel in step (3) is replaced by silicon-based aerogel;

[0041] The specific steps are as follows:

[0042] (1) Add 12 g of Span 80 and 8 g of Tween 80 to 100 g of deionized water and stir at 300 rpm for 30 min to obtain an emulsifier solution; mix 40 g of styrene, 4 g of butyl acrylate and 4 g of isooctyl acrylate to obtain a monomer mixture A; mix 2 g of acrylic acid, 20 g of styrene, 10 g of butyl acrylate and 20 g of isooctyl acrylate to obtain a monomer mixture B; mix 0.3 g of ammonium persulfate, 0.25 g of sodium bicarbonate and 30 g of deionized water to obtain an initiator solution;

[0043] (2) 48 g of monomer mixture A, 10 g of octaphenyl cage-type polysilsesquioxane and 20 g of silicon-based aerogel were added to 120 g of emulsifier solution, stirred at 300 rpm for 30 min, then heated to 85 °C, 10 g of initiator solution was added dropwise, and after the addition was complete, stirring was continued at 300 rpm for 4 h. Then 52 g of monomer mixture B and 20 g of initiator solution were added dropwise, and after the addition was complete, stirring was continued at 300 rpm for 4 h. Finally, the temperature was cooled to room temperature, and ammonia water (concentration of 28 wt%) was added to adjust the pH to 8 to obtain a modified styrene-acrylic emulsion.

[0044] (3) 100 g of modified styrene-acrylic emulsion, 0.8 g of dispersant (sodium salt of polycarboxylate, model number NOPCO SN-Dispersant 5040), and 3 g of wetting agent (ethylene glycol butyl ether) were stirred at 1200 rpm for 15 min, and then 0.5 g of thickener (hydroxyethyl cellulose, model number Natrosol 250MBR) and 0.3 g of defoamer (organic silicone defoamer, model number BYK-035) were added and stirred at 1200 rpm for 15 min to obtain the coating.

[0045] Comparative Example 2:

[0046] The difference between Comparative Example 2 and Example 2 is that the octaphenyl cage-type polysilsesquioxane in step (3) is replaced by cage-type polysilsesquioxane;

[0047] The specific steps are as follows:

[0048] (1) 20 g of silica-based aerogel, 250 g of anhydrous ethanol and 0.5 g of vinyltrimethoxysilane were added to 350 g of deionized water, stirred and refluxed at 80 °C for 3 h, centrifuged, washed with anhydrous ethanol three times, and vacuum dried to obtain olefinated silica-based aerogel;

[0049] (2) Add 12 g of Span 80 and 8 g of Tween 80 to 100 g of deionized water and stir at 300 rpm for 30 min to obtain an emulsifier solution; mix 40 g of styrene, 4 g of butyl acrylate and 4 g of isooctyl acrylate to obtain a monomer mixture A; mix 2 g of acrylic acid, 20 g of styrene, 10 g of butyl acrylate and 20 g of isooctyl acrylate to obtain a monomer mixture B; mix 0.3 g of ammonium persulfate, 0.25 g of sodium bicarbonate and 30 g of deionized water to obtain an initiator solution;

[0050] (3) 48 g of monomer mixture A, 10 g of cage-type polysilsesquioxane and 20 g of olefinic silicon-based aerogel were added to 120 g of emulsifier solution, stirred at 300 rpm for 30 min, then heated to 85 °C, 10 g of initiator solution was added dropwise, and after the addition was complete, stirring was continued at 300 rpm for 4 h. Then 52 g of monomer mixture B and 20 g of initiator solution were added dropwise, and after the addition was complete, stirring was continued at 300 rpm for 4 h. Finally, the temperature was cooled to room temperature, and ammonia water (concentration of 28 wt%) was added to adjust the pH to 8 to obtain a modified styrene-acrylic emulsion.

[0051] (4) 100 g of modified styrene-acrylic emulsion, 0.8 g of dispersant (sodium salt of polycarboxylate, model number NOPCO SN-Dispersant 5040), and 3 g of wetting agent (ethylene glycol butyl ether) were stirred at a speed of 1200 rpm for 15 min, and then 0.5 g of thickener (hydroxyethyl cellulose, model number Natrosol 250MBR) and 0.3 g of defoamer (organic silicone defoamer, model number BYK-035) were added and stirred at a speed of 1200 rpm for 15 min to obtain a coating.

[0052] Comparative Example 3:

[0053] The difference between Comparative Example 3 and Example 2 is that the octaphenyl cage-type polysilsesquioxane in step (3) is added along with the monomer mixture B;

[0054] The specific steps are as follows:

[0055] (1) 20 g of silica-based aerogel, 250 g of anhydrous ethanol and 0.5 g of vinyltrimethoxysilane were added to 350 g of deionized water, stirred and refluxed at 80 °C for 3 h, centrifuged, washed with anhydrous ethanol three times, and vacuum dried to obtain olefinated silica-based aerogel;

[0056] (2) Add 12 g of Span 80 and 8 g of Tween 80 to 100 g of deionized water and stir at 300 rpm for 30 min to obtain an emulsifier solution; mix 40 g of styrene, 4 g of butyl acrylate and 4 g of isooctyl acrylate to obtain a monomer mixture A; mix 2 g of acrylic acid, 20 g of styrene, 10 g of butyl acrylate and 20 g of isooctyl acrylate to obtain a monomer mixture B; mix 0.3 g of ammonium persulfate, 0.25 g of sodium bicarbonate and 30 g of deionized water to obtain an initiator solution;

[0057] (3) 48 g of monomer mixture A and 20 g of olefinic silicon-based aerogel were added to 120 g of emulsifier solution, stirred at 300 rpm for 30 min, then heated to 85 °C, 10 g of initiator solution was added dropwise, and after the addition was complete, stirring was continued at 300 rpm for 4 h. Then 52 g of monomer mixture B, 10 g of octaphenyl cage-type polysilsesquioxane and 20 g of initiator solution were added dropwise, and after the addition was complete, stirring was continued at 300 rpm for 4 h. Finally, the temperature was cooled to room temperature, and ammonia water (concentration of 28 wt%) was added to adjust the pH to 8 to obtain a modified styrene-acrylic emulsion.

[0058] (4) 100 g of modified styrene-acrylic emulsion, 0.8 g of dispersant (sodium salt of polycarboxylate, model number NOPCO SN-Dispersant 5040), and 3 g of wetting agent (ethylene glycol butyl ether) were stirred at a speed of 1200 rpm for 15 min, and then 0.5 g of thickener (hydroxyethyl cellulose, model number Natrosol 250MBR) and 0.3 g of defoamer (organic silicone defoamer, model number BYK-035) were added and stirred at a speed of 1200 rpm for 15 min to obtain a coating.

[0059] Comparative Example 4:

[0060] The difference between Comparative Example 4 and Example 2 is that: in step (3), the order of adding monomer mixture A and monomer mixture B is replaced;

[0061] The specific steps are as follows:

[0062] (1) 20 g of silica-based aerogel, 250 g of anhydrous ethanol and 0.5 g of vinyltrimethoxysilane were added to 350 g of deionized water, stirred and refluxed at 80 °C for 3 h, centrifuged, washed with anhydrous ethanol three times, and vacuum dried to obtain olefinated silica-based aerogel;

[0063] (2) Add 12 g of Span 80 and 8 g of Tween 80 to 100 g of deionized water and stir at 300 rpm for 30 min to obtain an emulsifier solution; mix 40 g of styrene, 4 g of butyl acrylate and 4 g of isooctyl acrylate to obtain a monomer mixture A; mix 2 g of acrylic acid, 20 g of styrene, 10 g of butyl acrylate and 20 g of isooctyl acrylate to obtain a monomer mixture B; mix 0.3 g of ammonium persulfate, 0.25 g of sodium bicarbonate and 30 g of deionized water to obtain an initiator solution;

[0064] (3) Add 52g of monomer mixture B, 10g of octaphenyl cage polysilsesquioxane and 20g of olefinic silicon-based aerogel to 120g of emulsifier solution, stir at 300 rpm for 30min, then heat to 85℃, add 10g of initiator solution dropwise, continue stirring at 300 rpm for 4h after the addition is complete, then add 48g of monomer mixture A and 20g of initiator solution dropwise, continue stirring at 300 rpm for 4h after the addition is complete, finally cool to room temperature, add ammonia water (concentration of 28wt%) to adjust the pH to 8, and obtain a modified styrene-acrylic emulsion;

[0065] (4) 100 g of modified styrene-acrylic emulsion, 0.8 g of dispersant (sodium salt of polycarboxylate, model number NOPCO SN-Dispersant 5040), and 3 g of wetting agent (ethylene glycol butyl ether) were stirred at a speed of 1200 rpm for 15 min, and then 0.5 g of thickener (hydroxyethyl cellulose, model number Natrosol 250MBR) and 0.3 g of defoamer (organic silicone defoamer, model number BYK-035) were added and stirred at a speed of 1200 rpm for 15 min to obtain a coating.

[0066] Performance testing:

[0067] Preparation of coating samples: The water-based thermal insulation coatings prepared in Examples 1-3 and Comparative Examples 1-4 were uniformly applied to a standard cement asbestos board substrate (size 150 mm × 70 mm × 4 mm), and a wire rod coater was used to control the wet film thickness to 200 ± 10 μm. The coatings were cured for 7 days under standard environmental conditions (temperature 23 ± 2°C, relative humidity 50 ± 5%) to obtain coating samples.

[0068] Thermal insulation: According to GB / T 25261-2018, use JTRG-IV building insulation tester and set the radiation intensity to 1000W / m 2 A T-type thermocouple was fixed on the surface of the coating sample at 30 cm from the heat source, and the maximum temperature difference between the surface and the back of the coating sample was recorded within 60 minutes. The arithmetic mean of the measured values ​​at 5 points was taken for each sample. The results are shown in Table 1.

[0069] Adhesion: According to GB / T 5210-2006, the bonding strength between the coating and the substrate was measured using an electronic universal testing machine. The results are shown in Table 1.

[0070] Weathering resistance: According to GB / T 1865-2009, use a xenon lamp aging chamber (irradiation intensity 0.55W / m², blackboard temperature 65±3℃) for 500 hours of continuous irradiation. Then, evaluate the powdering of the coating according to GB / T 1766-2008, test the adhesion of the coating after aging, and calculate the adhesion retention rate after aging.

[0071] Temperature change resistance: According to JG / T25-2017, freeze-thaw cycle test at -20℃ / 50℃ was carried out 20 times. The cracking of the coating was evaluated according to GB / T1766-2008. The adhesion of the sample coating after freeze-thaw cycle was tested and the adhesion retention rate was calculated.

[0072] Table 1 Performance test results

[0073] Maximum temperature difference / ℃ Bond strength / MPa Weather resistance (powdering level) Adhesion retention rate after aging / % Temperature deformation resistance (number of cracks) Adhesion retention rate after freeze-thaw cycles / % Example 1 14.1 3.3 Level 0 86.9 No cracks 84.6 Example 2 14.3 3.2 Level 0 88.2 No cracks 85.8 Example 3 14.4 3.0 Level 0 87.5 No cracks 85.2 Comparative Example 1 12.1 2.9 Level 0 85.3 No cracks 83.6 Comparative Example 2 11.5 3.1 Level 1 82.1 1 micro-line 80.7 Comparative Example 3 12.9 2.8 Level 0 84.4 1 micro-line 82.4 Comparative Example 4 13.2 2.1 Level 2 68.9 3 micro lines 67.5

[0074] Data Analysis:

[0075] As can be seen from the data of Examples 1-3 in Table 1, the water-based thermal insulation coating prepared by the present invention exhibits excellent overall performance, which can be attributed to its unique multilayer structural design and material combination. The coating's outstanding thermal insulation performance stems from the multi-level insulation structure formed by the silica-based aerogel and the polymer matrix. This structure effectively blocks heat conduction paths and reduces heat transfer. Furthermore, the coating exhibits high bond strength, excellent weather resistance, and resistance to temperature fluctuations. In practical applications, this coating can significantly reduce building surface temperatures, reduce energy consumption, extend building service life, and effectively mitigate the urban heat island effect, providing an ideal exterior wall protection solution for green buildings.

[0076] As can be seen from the data of Example 2 and Comparative Example 1 in Table 1, Example 2 exhibits superior overall performance, particularly thermal insulation, compared to Comparative Example 1. This may be due to the introduction of vinyl functional groups on the surface of the olefinic silicon-based aerogel, which enables chemical bonding with the styrene-acrylate copolymer during the emulsion polymerization process. This covalent bonding effectively improves the dispersibility of the silicon-based aerogel, thereby forming a more uniformly blocked heat conduction path and improving thermal insulation.

[0077] From the data of Example 2 and Comparative Example 2 in Table 1, it can be seen that Example 2 exhibits better thermal insulation, weather resistance and temperature change resistance than Comparative Example 2. This difference may be related to the special structure of octaphenyl cage polysilsesquioxane (POSS). The rigid structure of the benzene ring can enhance the steric effect of the POSS core and delay the thermal motion of the polymer chain segments; secondly, the π-π interaction between the phenyl group and the styrene-acrylate segment may form dynamic physical cross-linking points, which dissipate energy through a reversible dissociation-recombination process during heating. This multiple action mechanism jointly maintains the structural integrity of the coating during long-term aging.

[0078] As can be seen from the data of Example 2 and Comparative Example 3 in Table 1, the difference in the timing of adding octaphenyl cage-type polysilsesquioxane leads to significant changes in the coating performance. In Example 2, this component is added early together with monomer mixture A, while in Comparative Example 3, it is added later with monomer mixture B. This adjustment of the process timing may have a profound impact on the material microstructure. In Example 2, octaphenyl cage-type polysilsesquioxane may form a synergistic network with the olefinic silicon-based aerogel in the early stage of polymerization. This early synergy may enable the two nanostructured components to establish an interaction during the emulsion particle formation stage. The rigid skeleton of the octaphenyl cage-type structure may serve as a molecular-level connecting bridge, linking the surface of the olefinic microspheres with the polymer backbone. The close spatial arrangement between these nanostructured components may form a multi-level thermal insulation barrier, enhancing the scattering and barrier effect of thermal radiation. In addition, the octaphenyl cage-type structure added later in Comparative Example 3 is difficult to penetrate into the interior of the formed polymer network and may be mainly distributed in the outer layer area of ​​the emulsion particles, unable to establish an effective interaction with the internal hollow microspheres. This separated distribution state weakens the synergistic effect of the two functional components, resulting in a decrease in thermal insulation performance.

[0079] As can be seen from the data of Example 2 and Comparative Example 4 in Table 1, the order of adding monomer mixtures A and B has a significant effect on the performance of the coating, which may be closely related to the polymer microstructure formed. In Example 2, mixture A rich in styrene hard monomers is added first, and mixture B containing a higher proportion of acrylate soft monomers is added later, while Comparative Example 4 reverses this order. The order adopted in Example 2 may promote the formation of a "hard core-soft shell" structure, that is, first a stable rigid core is constructed based on styrene, and then an elastic shell is formed based on acrylate. This gradient structure may optimize the stress distribution and transfer mechanism, so that the coating can have appropriate elastic response capabilities while maintaining overall rigidity. In addition, the hard core formed first may provide a more compatible chemical environment for octaphenyl cage-type polysilsesquioxane, promoting it to form a more stable interaction with the benzene ring of the styrene unit through π-π stacking. This strong interaction may construct a network structure with a nano-enhancement effect, improving the material's resistance to ultraviolet aging. In contrast, the initial polymerization of the soft monomer in Comparative Example 4 may have formed an overly soft initial structure, making it difficult for the subsequent hard monomer to form an effective reinforcement phase, disrupting the overall structural balance between rigidity and flexibility. This unbalanced microstructure can cause the coating to expand and contract uncoordinatedly with temperature changes, forming areas of stress concentration and microcracks. The polymerization sequence in Example 2 may also optimize the formation of the crosslinked network, resulting in a more uniform distribution of crosslinking points, thereby improving the coating's structural stability and durability under environmental stress.

[0080] Those skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of the present invention is limited to these examples. Within the scope of the present invention, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of the different aspects of the present invention as described above, which are not provided in detail for the sake of simplicity.

Claims

1. A water-based thermal insulation coating, characterized in that: The composition comprises the following components by weight: 80-120 parts of modified styrene-acrylic emulsion, 0.3-1 parts of dispersant, 2-4 parts of wetting agent, 0.3-0.8 parts of thickener and 0.1-0.5 parts of defoaming agent; The preparation steps of the modified styrene-acrylic emulsion are as follows: S1: mixing an emulsifier and deionized water to obtain an emulsifier solution; mixing styrene, butyl acrylate, and isooctyl acrylate to obtain a monomer mixture A; mixing acrylic acid, styrene, butyl acrylate, and isooctyl acrylate to obtain a monomer mixture B; and mixing ammonium persulfate, sodium bicarbonate, and deionized water to obtain an initiator solution; S2: Add monomer mixture A, octaphenyl cage polysilsesquioxane and olefinic silicon-based aerogel to the emulsifier solution, stir for 20-40 minutes, then heat to 83-87°C, add initiator solution dropwise, stir for 3.5-4.5 hours after the addition is complete, then add monomer mixture B and initiator solution dropwise, stir for 3.5-4.5 hours after the addition is complete, finally cool to room temperature, add ammonia water to adjust the pH to 7.9-8.3, and obtain a modified styrene-acrylic emulsion; The weight ratio of the emulsifier to deionized water in the emulsifier solution of step S1 is 16-25:80-120; the weight ratio of styrene, butyl acrylate and isooctyl acrylate in monomer mixture A is 30-50:3-5:3-5; the weight ratio of acrylic acid, styrene, butyl acrylate and isooctyl acrylate in monomer mixture B is 1.5-2.5:15-25:8-12:15-25; the weight ratio of ammonium persulfate, sodium bicarbonate and deionized water in the initiator solution is 0.25-0.35:0.2-0.3:25-35; In step S2, the weight ratio of monomer mixture A, octaphenyl cage-type polysilsesquioxane, olefinic silicon-based aerogel, emulsifier solution, initiator solution and monomer mixture B is 36-60:8-12:15-25:95-145:25-35:39.5-64.5; In step S2, the olefinated silicon-based aerogel is obtained by modifying the silicon-based aerogel with vinyltrimethoxysilane; the weight ratio of the vinyltrimethoxysilane to the silicon-based aerogel is 0.3-0.8:15-25; the average particle size of the silicon-based aerogel is 10-20 μm, and the specific surface area is 500-800 m 2 / g.

2. The water-based thermal insulation coating according to claim 1, characterized in that: In step S1, the emulsifier is a mixture of Span 80 and Tween 80 in a weight ratio of 10-15:6-10.

3. The water-based thermal insulation coating according to claim 1, characterized in that: In step S2, the weight ratio of the first dropwise addition of the initiator solution to the second dropwise addition of the initiator solution is 8-12:17-23.

4. The water-based thermal insulation coating according to claim 1, characterized in that: The dispersant is sodium polycarboxylate; the wetting agent is ethylene glycol butyl ether; the thickener is hydroxyethyl cellulose; and the defoaming agent is an organosilicon defoaming agent.

5. A method for preparing a water-based thermal insulation coating according to any one of claims 1 to 4, characterized in that: The following steps are involved: The modified styrene-acrylic emulsion, dispersant and wetting agent are stirred at a speed of 1000-1500 rpm for 10-20 minutes, and then a thickener and a defoaming agent are added, and the stirring is continued at a speed of 1000-1500 rpm for 10-20 minutes to obtain a water-based thermal insulation coating.