Thermal insulation coating based on temperature-controlled phase change material, method for its production and use

Abstract

The application discloses a kind of heat insulation coating based on phase change material and its preparation method and application, belong to functional coating technical field.The coating includes A component and B component, A component includes water-based resin, film-forming aid, antifreezing agent and deionized water;B component includes self-repairing elastic phase change microcapsule, pigment, heat insulation composite filler and functional aid.The self-repairing elastic microcapsule adopts PLGA and polycaprolactone diol composite shell, core material uses phase change material and self-repairing resin, the heat insulation composite filler includes boron nitride, nanometer silicon dioxide and montmorillonite, the coating prepared simultaneously has excellent heat insulation performance, self-repairing function, interface bonding strength, mechanical property and storage stability, can be widely applied in building energy saving, industrial equipment protection, traffic vehicle and electronic appliance etc.

Description

Technical Field

[0001] This invention relates to the field of functional coatings technology, specifically to a self-healing heat-insulating coating based on temperature-controlled phase change materials, its preparation method, and its application. Background Technology

[0002] Building energy conservation and industrial equipment insulation are important ways to reduce energy consumption. Thermal insulation coatings can effectively reduce surface and indoor temperatures by reflecting sunlight or blocking heat conduction. However, traditional thermal insulation coatings are mostly passive protection. During long-term use, microcracks develop in the coating due to factors such as thermal expansion and contraction, external impact, or substrate deformation. As a result, the thermal insulation performance deteriorates rapidly, and the cracks are difficult to repair automatically, eventually leading to coating failure.

[0003] Phase change materials (PCMs) are widely used in thermal insulation coatings to achieve active temperature regulation due to their ability to absorb or release a large amount of latent heat during phase change. The addition of PCMs to coatings is mostly achieved by adding PCM microcapsules, but existing PCM microcapsules have the following technical bottlenecks: (1) Single PCM microcapsules only have energy storage function and cannot repair coating damage; (2) Ordinary self-healing microcapsules have a single triggering mechanism and are difficult to achieve intelligent response during the high-temperature period when the coating needs repair the most; (3) Microcapsule shells are brittle and easily broken during coating processing and use; (4) Microcapsules have poor compatibility with the coating matrix, affecting the mechanical properties and appearance of the coating; (5) Polymer microcapsule shells themselves have problems such as poor thermal conductivity and mismatch with the mechanical properties of the matrix, resulting in a decrease in the overall thermal conductivity of the coating and weak interfacial bonding, which limits their application effect. Summary of the Invention

[0004] To address the above problems, this invention provides a thermal insulation coating based on temperature-controlled phase change material, its preparation method, and its application.

[0005] In a first aspect, a heat-insulating coating based on a temperature-controlled phase change material is provided, comprising component A and component B, wherein, by weight: component A comprises 80-100 parts of waterborne resin, 3-6 parts of film-forming aid, 2-4 parts of antifreeze, and 20-40 parts of deionized water; component B comprises 20-40 parts of self-healing elastic phase change microcapsules, 10-20 parts of pigment, 6-15 parts of heat-insulating composite filler, and 1.5-4.6 parts of functional additives; wherein the waterborne resin is selected from resins that can crosslink with amino or epoxy groups.

[0006] Furthermore, the thermal insulation composite filler comprises 3-8 parts boron nitride, 2-5 parts nano-silica, and 1-2 parts montmorillonite.

[0007] Furthermore, the self-healing elastic phase change microcapsule adopts a composite shell of PLGA and polycaprolactone diol, and the core material includes phase change material, hydroxyl-terminated polydimethylsiloxane and methyl tributanone oxime silane.

[0008] This invention employs a composite filler system in the coating formulation to compensate for the defects brought about by the introduction of microcapsules, especially their shells. Specifically: Flaky boron nitride is added as a thermally conductive enhancing filler. The boron nitride forms a three-dimensional thermally conductive network in the coating, rapidly transferring ambient heat to the microcapsule surface, enabling the phase change material in the core to respond promptly to temperature changes. Nano-silica is introduced; its surface is rich in hydroxyl groups, which can form hydrogen bonds and chemical bonds with the epoxy resin matrix. Simultaneously, it fills the microscopic voids at the interface between the microcapsules and the matrix or between microcapsules, forming a "mechanical transition layer" from the microcapsule shell to the resin matrix. This effectively disperses stress concentration, prevents the microcapsules from becoming weak points in the coating, and improves mechanical properties. The added montmorillonite's lamellar structure aligns during the coating drying process, forming a barrier layer that effectively delays the penetration of moisture and organic solvents into the microcapsule shell, thus improving the storage stability of the microcapsules.

[0009] Furthermore, the functional additives include 0.5-1.5 parts of dispersant, 0.2-0.8 parts of wetting agent, 0.3-0.8 parts of defoamer, and 0.5-1.5 parts of thickener.

[0010] Furthermore, the dispersant is selected from sodium polycarboxylate or ammonium polyacrylate dispersants; the wetting agent is selected from acetylenic diol surfactants or silicone wetting agents; the defoamer is selected from mineral oil or polyether defoamers; and the thickener is selected from polyurethane thickeners or alkali-swellable acrylic thickeners.

[0011] Furthermore, the waterborne resin is selected from resins that can crosslink with amino or epoxy groups, specifically at least one of waterborne acrylic resin, waterborne epoxy resin, waterborne amino resin, and waterborne phenolic resin.

[0012] Secondly, a method for preparing the above-mentioned coating is provided, comprising the following steps: Step 1): Weigh out deionized water, dispersant, wetting agent and 1 / 2 of the amount of defoamer according to the formula, mix them evenly under stirring at 600-800 rpm, slowly add pigment and heat insulation composite filler, increase the speed to 1500-2000 rpm, disperse at high speed for 20-30 min, transfer the dispersed slurry to a sand mill and grind it to a fineness ≤30μm to obtain functional color paste; Step 2): Weigh out the self-healing elastic phase change microcapsules according to the formula, add a small amount of deionized water, stir with a glass rod to moisten, and let stand for 10-15 minutes to obtain the self-healing elastic phase change microcapsule pre-dispersion slurry. Step 3): In the functional color paste of Step 1, slowly add the water-based resin, film-forming aid and antifreeze under stirring at 300-600 rpm, stir for 10-15 min, slowly add the self-healing elastic phase change microcapsule pre-dispersion slurry of Step 2), and continue stirring for 15-20 min to make the self-healing elastic phase change microcapsules uniformly dispersed. Step 4): Add the remaining defoamer, and slowly add the thickener while stirring at 300-400 rpm. Adjust the viscosity of the coating to 80-100 KU (Stormer viscometer), and filter it through a 100-mesh sieve to obtain the coating.

[0013] Furthermore, in step 2), the amount of deionized water added is 50%-100% of the mass of the microcapsules.

[0014] Furthermore, the preparation method of self-healing elastic phase change microcapsules includes: Step 1: Weigh the phase change material, hydroxyl-terminated polydimethylsiloxane, methyltributanone oxime silane and organotin catalyst according to the formula, heat to 40-60℃, and keep warm and mix for 30-60 min under stirring at 200-400 rpm until all components are mixed evenly to obtain the core material solution. Step 2: Dissolve polylactic acid-glycolic acid copolymer (PLGA, viscosity 0.2-0.8 dL / g) and polycaprolactone diol in dichloromethane, stir until completely dissolved, and prepare a solution with a concentration of 30-50 mg / mL to obtain an oil phase solution; Step 3: While stirring at 300-500 rpm, slowly add the composite core solution from Step 1 to the oil phase solution from Step 2. Transfer the resulting mixture to a high-speed homogenizer and emulsify at 8000-12000 rpm for 2-5 min to obtain a stable primary emulsion. Step 4: Dissolve polyvinyl alcohol (PVA, degree of hydrolysis 87%-89%) in deionized water to prepare a 1-2 wt% aqueous solution. Under stirring at 400-600 rpm, slowly add the primary emulsion from step 3 to the aqueous solution to obtain a secondary emulsion. Step 5: Continue stirring the double emulsion from Step 4 at room temperature for 4-6 hours to precipitate microcapsule solids. After natural sedimentation, filter the solids and add an aqueous solution of silane coupling agent with a pH of 4-5. Heat the solution to 40-50°C and react for 2-4 hours. After filtration, wash the solids with deionized water and ethanol alternately 2-3 times and dry them under vacuum at 30-40°C for 24 hours to obtain self-healing elastic phase change microcapsules.

[0015] This invention uses a functionalized silane coupling agent to modify the surface of microcapsules, introducing amino and epoxy active functional groups on the surface of the microcapsules. When the modified microcapsules are dispersed in a coating system composed of epoxy resin and amine curing agent, the amino groups on the surface of the microcapsules undergo ring-opening addition reactions with the epoxy groups of the epoxy resin, and the epoxy groups on the surface of the microcapsules undergo ring-opening reactions with the amino groups of the amine curing agent. This transforms the microcapsules from traditional physical fillers into covalent bond nodes of the coating crosslinking network, achieving chemical anchoring between the microcapsules and the substrate, thereby improving adhesion. This invention uses a composite of phase change material and self-healing resin as the core material of microcapsules. When the microcapsules are intact, the phase change material performs energy storage and temperature regulation through phase change heat absorption / release. When the coating develops microcracks due to temperature stress or external force, the cracks propagate and puncture the microcapsules. The phase change material in the core material melts at high temperature, which on the one hand uses the volume expansion effect to generate internal pressure to assist the microcapsule rupture, and on the other hand significantly reduces the viscosity of the repair system, promoting the rapid flow of the repair agent into the microcracks under capillary action. Subsequently, the self-healing resin solidifies, and the phase change material, after cooling, is dispersed in the system as a physical filler phase, realizing the characteristic of "high-temperature triggered repair".

[0016] This invention uses a composite of polylactic acid-glycolic acid copolymer (PLGA) and polycaprolactone diol (PCL-diol) as the microcapsule shell material. PLGA provides excellent film-forming properties and structural strength, ensuring smooth microcapsule formation during the emulsification-solvent evaporation process. PCL-diol, as a flexible segment, forms a "rigid-flexible" composite network structure with PLGA through physical molecular chain entanglement, providing elasticity. Ultimately, this allows the microcapsule shell to maintain sensitivity to crack stress while achieving excellent flexibility and impact resistance.

[0017] In the microcapsule preparation process, the polyvinyl alcohol (PVA) retained on the solid surface of the microcapsules undergoes a condensation reaction with the added hydrolyzed silane coupling agent due to the abundance of hydroxyl groups on the PVA molecular chain. This forms Si-OC covalent bonds, thereby constructing a PVA-silane hybrid crosslinking network on the microcapsule surface. This simplifies the preparation process by avoiding repeated washing. Furthermore, the resulting hybrid coating layer has a unique gradient structure—the inner layer is physically bonded to the PLGA shell, while the outer layer is chemically anchored to the coating matrix through the active functional groups (amino / epoxy groups) of the silane coupling agent. This structure forms a mechanical property gradient transition layer between the microcapsule and the matrix, effectively alleviating interfacial stress concentration. The PVA molecular chain provides a large number of hydroxyl groups, offering abundant reaction sites for the grafting of the silane coupling agent. The physical entanglement between the polyvinyl alcohol layer and the PLGA shell provides the first anchoring, while the chemical crosslinking of polyvinyl alcohol and silane and the chemical bonding of silane to the matrix provide the second anchoring. This dual anchoring mechanism enables the microcapsules to resist interfacial degradation under harsh conditions such as humid heat aging and thermal cycling in the coating. The polyvinyl alcohol-silane hybrid network forms a dense physical barrier on the surface of the microcapsules, effectively preventing the penetration of moisture and organic solvents into the shell and preventing leakage of the core material during coating storage.

[0018] Furthermore, the mass ratio of the phase change material, hydroxyl-terminated polydimethylsiloxane, methyltributanone oxime silane, and organotin catalyst is 100:50-80:15-25:0.5-2 parts.

[0019] Furthermore, the amount of polycaprolactone diol added is 5%-20% of the mass of PLGA.

[0020] Furthermore, the silane coupling agent is selected from 3-aminopropyltriethoxysilane (KH550) or 3-glycidoxypropyltrimethoxysilane (KH560), and the amount added is 1-3% of the solid mass of the microcapsule.

[0021] Furthermore, the amount of polycaprolactone diol added is 5%-20% of the mass of PLGA, serving as a shell toughening modifier.

[0022] Furthermore, in step 3, the mass ratio of the mixed control core to the wall material is 1:0.8-1.5.

[0023] Furthermore, in step 4, the volume ratio of the oil phase to the water phase is controlled at 1:3-5, and stirring is continued for 15-30 minutes.

[0024] Thirdly, the application of the above-mentioned coating in the fields of building energy conservation, industrial equipment protection, transportation vehicles, or electronic appliances is provided. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially. Example 1

[0026] Preparation of self-healing elastic phase change microcapsules Step 1: Weigh 100 g of phase change material (n-octadecane, phase change temperature 28℃, phase change enthalpy 210 J / g), 70 g of hydroxyl-terminated polydimethylsiloxane (viscosity 800 mPa·s), 20 g of methyl tributanone oxime silane, and 1 g of dibutyltin dilaurate. Heat to 45℃ and mix at 300 rpm for 45 min until all components are evenly mixed to obtain the core material solution.

[0027] Step 2: Weigh 10 g of polylactic acid-glycolic acid copolymer (PLGA, viscosity 0.5 dL / g, lactic acid:glycolic acid = 50:50) and 1.5 g of polycaprolactone diol (average molecular weight 2000, Aladdin) (the amount added is 15% of the mass of PLGA), dissolve them in dichloromethane, bring the volume to 300 mL, and stir until completely dissolved to obtain an oil phase solution with a concentration of 38 mg / mL.

[0028] Step 3: While stirring at 400 rpm, slowly add the core material solution from Step 1 dropwise to the oil phase solution from Step 2, controlling the mass ratio of core to wall material to be 1:1.2. Transfer the mixture to a high-speed homogenizer and emulsify at 10,000 rpm for 3 minutes to obtain a stable primary emulsion.

[0029] Step 4: Weigh 10 g of polyvinyl alcohol (PVA, degree of hydrolysis 88%), dissolve it in deionized water, and bring the volume to 1000 mL to prepare a 1 wt% aqueous solution. While stirring at 500 rpm, slowly add the primary emulsion from Step 3 to the aqueous phase, controlling the volume ratio of the oil phase to the water phase to be 1:4, and continue stirring for 20 min to obtain the secondary emulsion.

[0030] Step 5: Transfer the double emulsion from Step 4 to a fume hood and continue stirring at room temperature for 5 hours to allow the dichloromethane to completely evaporate and precipitate the microcapsule solids. After natural sedimentation, filter to retain the microcapsule solids (no washing required).

[0031] Step 6: Dissolve 1.5 g of 3-aminopropyltriethoxysilane (KH550) in 200 mL of deionized water, adjust the pH to 4.5 with glacial acetic acid, and heat to 45°C. Add the unwashed microcapsule solid to the silane solution and stir at 45°C for 3 h. After the reaction, filter and wash twice alternately with deionized water and ethanol to remove unreacted silane coupling agent and free PVA. Dry under vacuum at 35°C for 24 h to obtain surface-functionalized self-healing elastic phase change microcapsules, denoted as MC-1.

[0032] Laser particle size analyzer testing showed that the average particle size of MC-1 was 52 μm, with a particle size distribution of 35-75 μm (D90=68 μm); differential scanning calorimetry testing showed that the phase transition enthalpy was 128 J / g, and the encapsulation rate was about 61%; scanning electron microscopy observation showed that the microcapsules were regular spherical with smooth surfaces and no obvious defects. Example 2

[0033] Preparation of self-healing elastic phase change microcapsules with different PCL addition amounts: Following the preparation method of Example 1, only the amount of polycaprolactone diol added was changed. The specific amounts are shown in the table below: serial number PCL addition amount (per PLGA mass) Average particle size Phase transition enthalpy Flexible MC-2 5% 50 μm 132 J / g lower flexibility MC-3 10% 51 μm 130 J / g Medium flexibility MC-4 20% 54 μm 125 J / g High flexibility Example 3

[0034] Following the microcapsule preparation method of Example 1, microcapsules with different silane coupling agents were prepared: The specific dosage and types of additives are shown in the table below: serial number Silane coupling agents MC-5 KH550 (Amino) MC-6 KH560 (Epoxy Group) MC-7 KH550 + KH560 (1:1 mass ratio) Comparative Example 1 The method of Example 1 was followed, but step 5 was changed to: after the microcapsules were solidified, they were first filtered, washed three times with deionized water and ethanol to remove PVA, dried, and then redispersed in KH550 solution for reaction; the remaining characteristics were the same as in Example 1, and the resulting microcapsules were denoted as MC-D1.

[0035] Comparative Example 2 The method of Example 1 was followed, but polycaprolactone diol was not added in step 2. PLGA was used as the shell material, and other characteristics were the same as in Example 1. The resulting microcapsules were designated MC-D2.

[0036] Comparative Example 3 The method of Example 1 was followed, but in step 1, an equal amount of terminal hydroxyl polydimethylsiloxane was used to replace the phase change material. Other characteristics were the same as in the example, and the resulting microcapsules were denoted as MC-D3. Example 4

[0037] Preparation of coatings: Step 1): Weigh out 30 g of deionized water, 1.0 g of dispersant, 0.4 g of wetting agent, and 0.3 g of half the amount of defoamer according to the formula, and mix them evenly at 700 rpm. Slowly add 4 g of boron nitride, 3 g of nano-silica, and 1.5 g of montmorillonite, increase the speed to 1800 rpm, and disperse at high speed for 25 min. Transfer the dispersed slurry to a sand mill and grind it to a fineness ≤30 μm to obtain the functional color paste.

[0038] Step 2): Weigh 30 g of MC-1 microcapsules according to the formula, add 20 g of deionized water (67% of the mass of the microcapsules), gently stir with a glass rod to moisten, and let stand for 12 min to obtain the microcapsule predispersed slurry.

[0039] Step 3): Transfer the functional color paste from Step 1 to a mixing tank. Slowly add 100 g of waterborne epoxy resin emulsion, 4 g of film-forming aid, and 3 g of antifreeze while stirring at 500 rpm. Stir for 12 min. Adjust the speed to 350 rpm and slowly add the microcapsule pre-dispersion slurry from Step 2. Continue stirring for 18 min to ensure uniform dispersion of the microcapsules.

[0040] Step 4): Add the remaining 0.3 g of defoamer, and slowly add 1.0 g of thickener while stirring at 350 rpm to adjust the coating viscosity to 90 KU. Filter the coating through a 100-mesh sieve to obtain the self-healing heat insulation coating, denoted as C-1.

[0041] The formula is as follows: Components Quality Component A Waterborne epoxy resin emulsion (50% solids content) 100 Film-forming aid (alcohol ester dodecyl) 4 Antifreeze (propylene glycol) 3 Deionized water 30 Component B Self-healing elastic phase change microcapsules (MC-1) 30 Titanium dioxide (R996) 15 Boron nitride (flake-like, 1-5 μm) 4 Nano-sized silica (20 nm) 3 Montmorillonite (Aladdin, M141491) 1.5 Dispersant (Weifang Luyi Chemical Co., Ltd., Sodium polycarboxylate dispersant 5040) 1.0 Wetting agent (acetylenic diol) 0.4 Defoamer (Maclean, polyether type P728891) 0.6 Thickener (Zhongke Hongtai, polyurethane type) 1.0 Example 5

[0042] Following the preparation method of Example 4, the amount of microcapsules added was varied to obtain the coating of this example. The amount of microcapsules added is shown in the table below: serial number Microcapsule types Microcapsule dosage (per serving) C-2 MC-1 20 C-3 MC-1 40 Example 6

[0043] The microcapsules prepared in Examples 2-3 were used to prepare coatings according to the preparation method in Example 4, as shown in the table below.

[0044] serial number Microcapsule types C-4 MC-3 C-5 MC-5 C-6 MC-6 C-7 MC-7 Comparative Example 4 The preparation method of Example 4 was followed, but boron nitride, nano-silica and montmorillonite were not added to component B. Only microcapsules and pigments were used. The resulting coating was denoted as C-D1.

[0045] Comparative Example 5 The coating was prepared according to the preparation method of Example 4, but using the MC-D1 microcapsules prepared in Comparative Example 1, and the resulting coating was denoted as C-D2.

[0046] Comparative Example 6 The coating was prepared according to the preparation method of Example 4, but using MC-D2 microcapsules prepared in Comparative Example 2, and the resulting coating was denoted as C-D3.

[0047] Comparative Example 7 Following the method of Example 4, but using MC-D3 microcapsules prepared in Comparative Example 3 (self-healing only, no phase change), the resulting coating is denoted as C-D4. Performance testing

[0048] The testing methods are shown in the table below: Test methods / conditions Evaluation indicators Thermal insulation performance Irradiate with an infrared lamp (375 W) at a distance of 30 cm from the coating, and record the equilibrium temperature and heating rate. Equilibrium temperature, heating rate Self-healing performance Cross-shaped cracks (50-100 μm wide) were made with a blade, and the sample was treated at 60℃ for 4 h and observed under a microscope. Crack closure rate and repair efficiency Adhesion Stroke method (GB / T 9286-1998) Level (0-5) Tensile strength Tested according to GB / T 528-2009 MPa Impact strength Test according to GB / T 1732-93 kg·cm thermal conductivity Heat flow method W / m·K Storage stability Accelerated storage at 50℃ for 30 days to test the retention rate of microcapsule core material. % 1. The results of the thermal insulation performance test are shown in the table below: Equilibrium temperature (°C) Heating rate (°C / min) Blank substrate 68.5 12.3 C-D4 50.2 7.8 C-D1 48.3 6.5 C-1 46.5 5.2 The coating C-1 of this invention has the lowest equilibrium temperature, which is 22.0℃ lower than that of the blank substrate. Comparing C-1 and C-D4: the coating containing phase change microcapsules has significantly better thermal insulation performance than the control group without phase change, proving that phase change materials have an active temperature regulation effect; comparing C-1 and C-D1: the coating containing boron nitride has better thermal insulation performance than the one without, proving that the thermally conductive filler accelerates the phase change response.

[0049] 2. The self-healing performance test results are shown in the table below: Crack width before repair Crack width after repair Closure rate Thermal insulation performance recovery rate after repair C-D2 50-100 μm 30-50 μm 40% 65% C-D3 50-100 μm 25-40 μm 50% 72% C-1 50-100 μm 10-20 μm 80% 92% Comparing C-1 and C-D2: Microcapsules using the in-situ crosslinking process with PVA + silane coupling agent showed significantly improved repair efficiency and thermal insulation recovery rate, proving that the polyvinyl alcohol-silane hybrid crosslinking network enhanced the interfacial bonding between the microcapsule and the matrix, enabling the repair agent to flow into the crack more effectively; Comparing C-1 and C-D3: Microcapsules with PCL toughened shells showed higher repair efficiency, proving that the shell flexibility helps the microcapsules to preferentially split under stress, rather than be flattened or pushed apart.

[0050] 3. Test results of interfacial bonding strength and mechanical properties Adhesion (Grade) Tensile strength (MPa) Impact strength (kg·cm) Adhesion after 1000 hours of damp heat aging C-D2 1 32 45 Level 2 C-7 0 36 52 Level 1 C-1 0 38 58 Level 0 Comparing C-1 and C-D2: The adhesion, tensile strength, and impact strength of the coating of this invention are significantly better than those of the conventional grafted group, proving that the dual anchoring mechanism formed by PVA retention and in-situ crosslinking of coupling agent significantly enhances the interfacial bonding; Comparing C-1 and C-7: The mechanical properties of the bifunctional group (amino + epoxy group) are better than those of the monofunctional group, proving the dual anchoring effect of the bifunctional group; After damp heat aging, the adhesion of C-1 remains at grade 0, while that of C-D2 drops to grade 2, proving that the barrier layer formed by the polyvinyl alcohol-silane hybrid network effectively resists the damage to the interface caused by damp heat aging.

[0051] 4. The test results for thermal conductivity and storage stability are shown in the table below. Thermal conductivity (W / m·K) Phase transition response time (s) Core material retention rate after 30 days of storage at 50℃ C-D1 0.25 180 82% C-1 0.42 75 96% After adding boron nitride, the thermal conductivity increased from 0.25 W / m·K to 0.42 W / m·K, an increase of 68%; the phase change response time was shortened from 180 seconds to 75 seconds, a reduction of 58%, proving that the thermally conductive network constructed by boron nitride effectively accelerated heat transfer; after adding montmorillonite, the core material retention rate increased from 82% to 96%, proving that the lamellar barrier effect of montmorillonite effectively delayed solvent penetration.

[0052] In summary, the coating of this invention is significantly superior to the comparative example in terms of thermal insulation performance, self-healing efficiency, interfacial bonding strength, mechanical properties, thermal conductivity, and storage stability, and has good application prospects.

Claims

1. A heat-insulating coating based on a temperature-controlled phase change material, characterized in that, Including components A and B, by weight: Component A includes 80-100 parts of water-based resin, 3-6 parts of film-forming aid, 2-4 parts of antifreeze, and 20-40 parts of deionized water; Component B includes 20-40 parts of self-healing elastic phase change microcapsules, 10-20 parts of pigments, 6-15 parts of heat-insulating composite fillers, and 1.5-4.6 parts of functional additives; In component A, the aqueous resin is selected from resins that can crosslink with amino or epoxy groups; In component B, the thermal insulation composite filler includes 3-8 parts boron nitride, 2-5 parts nano silica, and 1-2 parts montmorillonite; The self-healing elastic phase change microcapsule uses a composite shell of PLGA and polycaprolactone diol, and the core material includes phase change material, hydroxyl-terminated polydimethylsiloxane, and methyl tributanone oxime silane.

2. The thermal insulation coating based on temperature-controlled phase change material according to claim 1, characterized in that, The functional additives include 0.5-1.5 parts of dispersant, 0.2-0.8 parts of wetting agent, 0.3-0.8 parts of defoamer, and 0.5-1.5 parts of thickener.

3. The thermal insulation coating based on temperature-controlled phase change material according to claim 1, characterized in that, The dispersant is selected from sodium polycarboxylate or ammonium polyacrylate dispersants; the wetting agent is selected from acetylenic diol surfactants or organosilicon wetting agents; the defoamer is selected from mineral oil or polyether defoamers; and the thickener is selected from polyurethane thickeners or alkali-swellable acrylic thickeners.

4. A method for preparing a coating according to any one of claims 1-3, characterized in that, Includes the following steps: Step 1): Weigh out deionized water, dispersant, wetting agent and 1 / 2 of the amount of defoamer according to the formula, mix them evenly under stirring at 600-800 rpm, slowly add pigment and heat insulation composite filler, increase the speed to 1500-2000 rpm, disperse at high speed for 20-30 minutes, transfer the dispersed slurry to a sand mill and grind it to a fineness ≤30μm to obtain functional color paste; Step 2): Weigh out the self-healing elastic phase change microcapsules according to the formula, add a small amount of deionized water, stir with a glass rod to moisten, and let stand for 10-15 minutes to obtain the self-healing elastic phase change microcapsule pre-dispersion slurry. Step 3): In the functional color paste of Step 1, slowly add the water-based resin, film-forming aid and antifreeze under stirring at 300-600 rpm, stir for 10-15 min, slowly add the self-healing elastic phase change microcapsule pre-dispersion slurry of Step 2), and continue stirring for 15-20 min to make the self-healing elastic phase change microcapsules uniformly dispersed. Step 4): Add the remaining defoamer, and slowly add the thickener while stirring at 300-400 rpm. Adjust the viscosity of the coating to 80-100 KU, and filter it through a 100-mesh sieve to obtain the coating.

5. The method according to claim 4, characterized in that, The amount of deionized water added in step 2) is 50%-100% of the mass of the self-healing elastic phase change microcapsules.

6. The method according to claim 4, characterized in that, The preparation method of the self-healing elastic phase change microcapsules includes: Step 1: Weigh the phase change material, hydroxyl-terminated polydimethylsiloxane, methyltributanone oxime silane and organotin catalyst according to the formula, heat to 40-60℃, and keep warm and mix for 30-60 min under stirring at 200-400 rpm until all components are mixed evenly to obtain the core material solution. Step 2: Dissolve polylactic acid-glycolic acid copolymer (PLGA, viscosity 0.2-0.8 dL / g) and polycaprolactone diol in dichloromethane, stir until completely dissolved, and prepare a solution with a concentration of 30-50 mg / mL to obtain an oil phase solution; Step 3: While stirring at 300-500 rpm, slowly add the composite core solution from Step 1 to the oil phase solution from Step 2. Transfer the resulting mixture to a high-speed homogenizer and emulsify at 8000-12000 rpm for 2-5 min to obtain a stable primary emulsion. Step 4: Dissolve polyvinyl alcohol (PVA, degree of hydrolysis 87%-89%) in deionized water to prepare a 1-2 wt% aqueous solution. Under stirring at 400-600 rpm, slowly add the primary emulsion from step 3 to the aqueous solution to obtain a secondary emulsion. Step 5: Continue stirring the double emulsion from Step 4 at room temperature for 4-6 hours to precipitate microcapsule solids. After natural sedimentation, filter the solids and add an aqueous solution of silane coupling agent with a pH of 4-5. Heat the solution to 40-50°C and react for 2-4 hours. After filtration, wash the solids with deionized water and ethanol alternately 2-3 times and dry them under vacuum at 30-40°C for 24 hours to obtain self-healing elastic phase change microcapsules.

7. The method according to claim 4, characterized in that, The silane coupling agent is selected from 3-aminopropyltriethoxysilane (KH550) or 3-glycidoxypropyltrimethoxysilane (KH560), and the amount added is 1-3% of the solid mass of the microcapsules.

8. The method according to claim 4, characterized in that, The amount of polycaprolactone diol added is 5%-20% of the mass of PLGA.

9. The method according to claim 4, characterized in that, In step 3, the mass ratio of the core material to the wall material in the mixing control is 1:0.8-1.5; In step 4 or / , the volume ratio of the oil phase solution to the aqueous phase solution is controlled to be 1:3-5, and stirring is continued for 15-30 min.

10. The application of the coating according to any one of claims 1-3 in the fields of building energy conservation, industrial equipment protection, transportation vehicles or electronic appliances.