Radiation cooling and heat insulation coating and preparation method thereof
By combining phase change energy storage insulation materials and low thermal conductivity materials to form an organic-inorganic hybrid structure coating, the problems of insufficient reflective insulation and high-temperature flame retardancy of insulation coatings are solved, achieving efficient radiative cooling and self-cleaning dustproof effects.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-02
- Publication Date
- 2026-05-15
AI Technical Summary
Existing heat insulation coatings are insufficient in terms of reflective heat insulation performance and high-temperature flame retardancy, making it difficult to effectively reduce the accumulation and conduction of solar radiation heat, and they are easily affected by dust pollution.
It combines phase change energy storage insulation materials with low thermal conductivity materials, and uses a primer composed of aerogel, hollow glass microspheres and sepiolite, while the topcoat forms an organic-inorganic hybrid structure through potassium silicate, silane modified silica sol, etc. It has excellent solar reflection and far-infrared radiation performance, and combines photocatalytic self-cleaning and antistatic adsorption properties.
It achieves efficient radiative cooling and heat insulation, possesses excellent high-temperature resistance, flame retardancy, and anti-fouling ability, reduces the accumulation and conduction of solar heat, and has long-lasting self-cleaning and dustproof performance.
Abstract
Description
Technical Field
[0001] This invention belongs to the field of coating technology, and particularly relates to a radiative cooling and heat insulation coating. This invention also relates to a method for preparing the coating. Background Technology
[0002] For a long time, the sun has continuously transmitted a large amount of heat to the earth through radiation of various frequencies and wavelengths. This has a particularly negative impact on people's production and lives, especially in areas such as building cooling, refrigerated transport, cold chain logistics, petrochemicals, and power equipment. Thermal insulation coatings, as a new type of functional coating, can effectively reduce the accumulation of solar radiation heat on object surfaces when applied. The petrochemical industry is a major producer and consumer of energy, requiring insulation for numerous pipelines and equipment. Furthermore, when applied to building exteriors, the reflective thermal insulation properties effectively reduce the accumulation of solar heat on the exterior walls and the amount of heat transferred indoors through the walls, thereby reducing the energy consumption of cooling equipment and improving the indoor environment. To reduce the surface temperature of objects under sunlight, prevent heat conduction, improve the working environment, and enhance work safety, reflective thermal insulation coatings, as a functional coating with outstanding energy-saving performance, are among the most promising green materials. Summary of the Invention
[0003] This invention provides a radiative cooling and heat insulation coating with excellent solar reflectivity and far-infrared emissivity. This invention also combines phase change energy storage heat insulation material with low thermal conductivity material. The product has phase change energy storage heat insulation properties, excellent high temperature resistance and flame retardancy and anti-fouling effect, and long-lasting radiative cooling and heat insulation effect.
[0004] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:
[0005] A radiative cooling and heat insulation coating, comprising a primer and a topcoat, wherein the primer is composed of the following raw materials in parts by weight: 65-75 parts deionized water, 0.1-0.2 parts pH adjuster, 0.2-0.5 parts defoamer, 0.4-0.6 parts hydroxypropyl methylcellulose, 1-1.5 parts wetting agent, 0.4-0.8 parts dispersant, 25-30 parts waterborne polyurethane emulsion, 7-15 parts aerogel, 7-10 parts hollow glass microspheres, 7-8 parts sepiolite, and 3-5 parts film-forming aid; the topcoat is composed of the following raw materials in parts by weight: ... 25-35 parts deionized water, 0.1-0.2 parts pH adjuster, 0.1-0.3 parts defoamer, 0.2-0.3 parts hydroxypropyl methylcellulose, 0.4-0.8 parts dispersant, 2-5 parts silica, 3-5 parts zirconium oxide, 10-15 parts rutile titanium dioxide, 10-16 parts infrared reflective filler, 2-3 parts film-forming aid, 0.1-0.2 parts defoamer, 4-7 parts far-infrared ceramic powder, 15-19 parts potassium silicate, 8-12 parts silica sol, 5-7 parts titanium sol, 5-7 parts silane-modified acrylic emulsion, and 3-4 parts conductive mica powder.
[0006] Furthermore, the aerogel is a hydrophobic aerogel powder with a pore size of 20 nm.
[0007] Furthermore, the rutile titanium dioxide is DuPont's R-902, and the infrared reflective filler is a mixture of Panhua Chemical's IR-1000 and Panengtuo's W400, with a mass ratio of IR-1000 to W400 of 1:1.
[0008] Furthermore, the aqueous polyurethane emulsion is prepared using the following raw materials in the following weight proportions according to the following preparation method:
[0009] a. Preparation of polyurethane prepolymer: 55 parts of polyester polyol from Huada Chemical were added to the reactor under stirring. The temperature was raised to 70℃ and 65 parts of isoflurane diisocyanate were added. The temperature was raised to 80-85℃ under nitrogen protection and the reaction was continued until the measured -NCO content reached the theoretical value. The above rotation speed and temperature were maintained, and 30 parts of acetone, 11 parts of 2,2-dimethylolpropionic acid, and 0.1 parts of dibutyltin dilaurate were added. The reaction was continued until the measured -NCO content reached the theoretical value. 5 parts of 1,4-butanediol were added to the reactor and the reaction was continued until the measured -NCO content reached the theoretical value to obtain the polyurethane prepolymer.
[0010] b. Neutralization, emulsification and aqueous chain extension of polyurethane prepolymer: Cool to 35℃, add 8 parts of triethanolamine, neutralize for 5 min, then add 180 parts of water, dilute and emulsify for 20 min, dissolve 2.5 parts of ethylenediamine in 30 parts of water, add the ethylenediamine aqueous solution dropwise to the reaction system over 10-15 minutes, and perform the aqueous chain extension reaction for 2 h. Distill off methyl ethyl ketone under reduced pressure to obtain an aqueous polyurethane emulsion.
[0011] Furthermore, the primer contains 4-6 parts of phase change microcapsules, which are prepared using the following raw materials in the following weight proportions according to the following preparation method:
[0012] 1) Add 50 parts of paraffin wax with a melting point of 37℃, 16 parts of methyl methacrylate, 9 parts of methacrylic acid, 76 parts of deionized water, 1 part of anionic emulsifier, 1 part of nonionic emulsifier and 0.3 parts of initiator azobisisobutyronitrile to an emulsification reactor. Emulsify for 30 minutes at a temperature 5℃ higher than the melting point of paraffin wax and a stirring speed of 800-1200 r / min. Reduce the stirring speed to 300 r / min and heat to 80-85℃ for 3 hours. Then add 1.5 parts of divinylbenzene and react for 3 hours. Cool down to 65℃ and add 0.05 parts of oxidant tert-butyl hydroperoxide and 0.05 parts of reducing agent FF6M alternately in two batches at 5-minute intervals. After the addition is completed, react at 65℃ for 0.5 hours.
[0013] 2) Cool down to below 45℃, add 1 part ammonia water to neutralize for 10 minutes, filter the obtained phase change microcapsule emulsion, wash with water 2-3 times, and then air dry to obtain phase change microcapsules.
[0014] Furthermore, the modulus of the potassium silicate is 3.85-4.35.
[0015] Furthermore, the silica sol is a silane-modified silica sol.
[0016] Furthermore, the silane-modified silica sol is prepared using the following raw materials in the following weight proportions according to the following preparation method:
[0017] S1: Add 12.5 parts of tetraethyl orthosilicate and 70 parts of ethanol to a reaction flask under stirring. Heat to 60°C, add 6.5 parts of deionized water, and adjust the pH to 8-9 by adding ammonia dropwise. Stir and react at 60°C for 2 hours. Then add 50 parts of deionized water to dilute, heat to boiling, and reflux to remove ethanol and ammonia, thus obtaining silica sol prepolymer.
[0018] S2: Cool the silica sol prepolymer to 60℃, add 5.5 parts of tetraethyl orthosilicate, and add ammonia to adjust the pH of the reaction solution to 8-9. React for 3 hours.
[0019] S3: Add 0.2 parts of KH550 and 0.6 parts of KH560 dropwise to modify the silica sol, react at 60℃ for 1 hour, and then concentrate by distillation at atmospheric pressure to obtain modified silica sol with a solid content of 30%.
[0020] Furthermore, the titanium sol is anatase nano-titanium dioxide sol, and the silane-modified waterborne acrylic emulsion is KRN8101 from Heshan Jinrunna New Material Co., Ltd.
[0021] The primer in the above-mentioned method for preparing a radiation cooling and heat insulation coating is prepared by the following method:
[0022] Step 1: Add deionized water, pH adjuster, defoamer, hydroxypropyl methylcellulose, wetting agent, and dispersant to the reaction vessel, disperse evenly, then add aerogel and stir until the aerogel is evenly dispersed to obtain aerogel slurry;
[0023] Step 2: Add water-based polyurethane emulsion to the dispersion vessel, and add hollow glass microspheres, sepiolite, film-forming aid, and aerogel slurry while stirring. Stir until uniform to obtain the primer of the radiation cooling and heat insulation coating.
[0024] The topcoat is prepared by the following method:
[0025] Deionized water, pH adjuster, defoamer, hydroxypropyl methylcellulose, and dispersant are added to a reaction vessel and stirred at 1800 rpm for 15 minutes. Then, silica, zirconium oxide, rutile titanium dioxide, infrared reflective filler, far-infrared ceramic powder, and conductive mica powder are added and stirred at 1800 rpm for 30 minutes. The stirring speed is then reduced to 600 rpm, and film-forming aids, silane-modified acrylic emulsion, defoamer, potassium silicate, silica sol, and titanium sol are added and stirred until homogeneous to obtain the topcoat of the radiation cooling and heat insulation coating.
[0026] The radiative cooling and heat insulation coating prepared in this invention combines water-based polyurethane emulsion and phase change microcapsules (two types of phase change energy storage and heat insulation materials) with aerogel, hollow glass microspheres, and sepiolite (a low thermal conductivity, flame-retardant, and fire-resistant material) in the primer, thus achieving phase change energy storage and heat insulation effects. The topcoat has excellent solar reflectivity and far-infrared radiation properties, effectively reflecting sunlight and dissipating its own heat into the absolute zero space of outer space in the form of electromagnetic waves, achieving the purpose of radiative cooling.
[0027] The topcoat of this invention uses potassium silicate, silane-modified silica sol, titanium sol, and silane-modified waterborne acrylic emulsion as film-forming resins to form an organic-inorganic hybrid cross-linked structure. It has excellent water resistance, abrasion resistance, and freeze-thaw resistance. The overall coating has excellent high-temperature resistance, Class A flame retardancy, and heat insulation and noise reduction effects. Furthermore, the topcoat combines photocatalytic self-cleaning properties with antistatic adsorption properties, providing anti-fouling, dust-proof, and self-cleaning effects. This reduces the impact of dust accumulation on the coating surface on the coating's reflective radiation function, resulting in long-lasting radiative cooling and heat insulation effects. Detailed Implementation
[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.
[0029] The waterborne polyurethane emulsion of this invention is prepared using the following raw materials in the following weight proportions according to the following method:
[0030] a. Preparation of polyurethane prepolymer: 55 parts of polyester polyol from Huada Chemical were added to the reactor under stirring. The temperature was raised to 70℃ and 65 parts of isoflurane diisocyanate were added. The temperature was raised to 80-85℃ under nitrogen protection and the reaction was carried out for 1.5 hours. The measured -NCO content reached the theoretical value. The above rotation speed and temperature were maintained, and 30 parts of acetone, 11 parts of 2,2-dimethylolpropionic acid, and 0.1 parts of dibutyltin dilaurate were added. The reaction was carried out for 2 hours. The measured -NCO content reached the theoretical value. 5 parts of 1,4-butanediol were added to the reactor and the reaction was carried out for 1 hour. The measured -NCO content reached the theoretical value, and the polyurethane prepolymer was obtained.
[0031] b. Neutralization, emulsification and aqueous chain extension of polyurethane prepolymer: Cool to 35℃, add 8 parts of triethanolamine, neutralize for 5 min, then add 180 parts of water, dilute and emulsify for 20 min, dissolve 2.5 parts of ethylenediamine in 30 parts of water, add the ethylenediamine aqueous solution dropwise to the reaction system over 10-15 minutes, and perform the aqueous chain extension reaction for 2 h. Distill off methyl ethyl ketone under reduced pressure to obtain an aqueous polyurethane emulsion.
[0032] The phase change microcapsules of this invention are prepared from the following raw materials in the following weight proportions according to the following method:
[0033] 1) Add 50 parts of paraffin wax with a melting point of 37℃, 16 parts of methyl methacrylate, 9 parts of methacrylic acid, 76 parts of deionized water, 1 part of anionic emulsifier, 1 part of nonionic emulsifier and 0.3 parts of initiator azobisisobutyronitrile to an emulsification reactor. Emulsify for 30 minutes at a temperature 5℃ higher than the melting point of paraffin wax and a stirring speed of 800-1200 r / min. Reduce the stirring speed to 300 r / min and heat to 80-85℃ for 3 hours. Then add 1.5 parts of divinylbenzene and react for 3 hours. Cool down to 65℃ and add 0.05 parts of oxidant tert-butyl hydroperoxide and 0.05 parts of reducing agent FF6M alternately in two batches at 5-minute intervals. After the addition is completed, react at 65℃ for 0.5 hours.
[0034] 2) Cool down to below 45℃, add 1 part ammonia water to neutralize for 10 minutes, filter the obtained phase change microcapsule emulsion, wash with water 2-3 times, and then air dry to obtain phase change microcapsules. Example
[0035] Examples 1-3 and Comparative Examples 1-4 each provide a radiation cooling and heat insulation coating primer, and the weight parts of each raw material are shown in Table 1 below.
[0036] Table 1
[0037] raw materials Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Deionized water 65 70 75 70 70 70 70 pH adjuster 0.1 0.2 0.2 0.2 0.2 0.2 0.2 Defoamer 0.2 0.5 0.4 0.5 0.5 0.5 0.5 Hydroxypropyl methylcellulose 0.4 0.6 0.5 0.6 0.6 0.6 0.6 wetting agent 1 1.5 1.2 1.5 1.5 1.5 1.5 dispersant 0.4 0.8 0.6 0.8 0.8 0.8 0.8 waterborne polyurethane emulsion 25 30 27 30 30 30 30（7026G） aerogel 7 15 13 0 15 15 15 Phase change microcapsules 4 6 0 6 0 6 6 Hollow glass microspheres 7 10 8 25 16 18 10 sepiolite 7 8 7.5 8 8 0 8 Film-forming aids 3 5 4 5 5 5 5
[0038] The aerogel mentioned above is a hydrophobic aerogel powder with a pore size of 20 nm; the film-forming aid mentioned above is 12-ol ester; Comparative Example 4 uses BASF's acrylic emulsion 7026G.
[0039] The preparation methods of the coatings provided in Examples 1-3 and Comparative Examples 1-4 specifically include the following steps:
[0040] The primer is prepared by the following method:
[0041] Step 1: Add deionized water, pH adjuster, defoamer, hydroxypropyl methylcellulose, wetting agent, and dispersant to the reaction vessel, disperse evenly, then add aerogel and stir until the aerogel is evenly dispersed to obtain aerogel slurry;
[0042] Step 2: Add water-based polyurethane emulsion to the dispersion vessel, and add hollow glass microspheres, sepiolite, film-forming aid, and aerogel slurry while stirring. Stir the phase change microcapsules evenly to obtain the primer of the radiation cooling and heat insulation coating.
[0043] The primers of the radiation cooling and heat insulation coatings prepared in Examples 1-3 and Comparative Examples 1-4 were subjected to relevant performance tests, and the test results are shown in Table 2 below.
[0044] Table 2
[0045] project Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Surface drying time / min 36 35 33 30 34 45 35 Practical time / h 4 4 4 4 4 4 4 Initial drying crack resistance (1mm) No abnormalities No abnormalities No abnormalities No abnormalities No abnormalities Slight cracks No abnormalities <![CDATA[Dry density (kg / m 3 )]]> 220 160 180 360 155 158 160 Thermal conductivity (W / (m·K)) 0.027 0.025 0.030 0.069 0.027 0.051 0.026 The thermal insulation temperature difference (°C) of 1 mm for water at 100°C 45 55 49 40 51 40 52 Bond strength (MPa) 0.9 0.8 0.8 0.9 0.8 0.6 0.7 Alkali resistance (168h) No abnormalities No abnormalities No abnormalities No abnormalities No abnormalities No abnormalities No abnormalities Water resistance (168h) No abnormalities No abnormalities No abnormalities No abnormalities No abnormalities No abnormalities No abnormalities Coating temperature resistance (10 cycles) No abnormalities No abnormalities No abnormalities No abnormalities No abnormalities No abnormalities No abnormalities
[0046] Test method for thermal insulation temperature difference (°C) of 1mm to 100℃ water: Apply a radiative cooling thermal insulation coating primer with a dry film thickness of 1mm to the surface of a stainless steel cup, fill the cup with boiling water at 100℃, and test the temperature T of the coating surface. The difference between 100℃ and T is the thermal insulation temperature difference.
[0047] The weight proportions of each raw material for the primer and topcoat of the radiative cooling and heat insulation coatings of Examples 1-3 and Comparative Examples 1-4 are shown in Table 3 below:
[0048] Table 3
[0049] raw materials Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Deionized water 25 35 30 30 30 30 30 pH adjuster 0.1 0.2 0.1 0.1 0.1 0.1 0.1 Defoamer 0.1 0.3 0.2 0.2 0.2 0.2 0.2 Hydroxypropyl methylcellulose 0.2 0.3 0.2 0.2 0.2 0.2 0.2 dispersant 0.4 0.8 0.6 0.6 0.6 0.6 0.6 silicon dioxide 2 5 4 4 4 4 4 Zirconia 5 3 4 4 4 4 7 Rutile titanium dioxide 10 15 12 4 12 12 12 IR-1000 5 6 8 12 0 8 8 W400 5 6 8 12 16 8 8 Film-forming aids 2 3 2.5 2.5 2.5 2.5 2.5 Defoamer 0.1 0.2 0.2 0.2 0.2 0.2 0.2 Far-infrared ceramic powder 4 7 6 6 6 6 6 Potassium silicate 15 19 17 17 17 23 17 silica sol 8 12 10 10 10 10 10 Titanium sol 5 7 6 6 6 0 6 Silane-modified acrylic emulsion 5 7 6 6 6 6 6 Conductive mica powder 3 4 3 3 3 3 0
[0050] The aforementioned rutile titanium dioxide is DuPont's R-902, and the potassium silicate has a modulus of 3.85-4.35. The titanium sol is anatase nano-titanium dioxide sol, and the silane-modified waterborne acrylic emulsion is KRN8101 from Heshan Jinrunna New Material Co., Ltd.
[0051] The silane-modified silica sol described above was prepared using the following raw materials in the following proportions by weight according to the following method:
[0052] S1: Add 12.5 parts of tetraethyl orthosilicate and 70 parts of ethanol to a reaction flask under stirring. Heat to 60°C, add 6.5 parts of deionized water, and adjust the pH to 8-9 by adding ammonia dropwise. Stir and react at 60°C for 2 hours. Then add 50 parts of deionized water to dilute, heat to boiling, and reflux to remove ethanol and ammonia, thus obtaining silica sol prepolymer.
[0053] S2: Cool the silica sol prepolymer to 60℃, add 5.5 parts of tetraethyl orthosilicate, and add ammonia to adjust the pH of the reaction solution to 8-9. React for 3 hours.
[0054] S3: Add 0.2 parts of KH550 and 0.6 parts of KH560 dropwise to modify the silica sol, react at 60℃ for 1 hour, and then concentrate by distillation at atmospheric pressure to obtain modified silica sol with a solid content of 30%.
[0055] The topcoat is prepared by the following method:
[0056] Deionized water, pH adjuster, defoamer, hydroxypropyl methylcellulose, and dispersant are added to a reaction vessel and stirred at 1800 rpm for 15 minutes. Then, silica, zirconium oxide, rutile titanium dioxide, infrared reflective filler, far-infrared ceramic powder, and conductive mica powder are added and stirred at 1800 rpm for 30 minutes. The stirring speed is then reduced to 600 rpm, and film-forming aids, silane-modified acrylic emulsion, defoamer, potassium silicate, silica sol, and titanium sol are added and stirred until homogeneous to obtain the topcoat of the radiation cooling and heat insulation coating.
[0057] The topcoat of the radiation cooling and heat insulation coatings in Examples 1-3 and Comparative Examples 1-4 were subjected to relevant performance tests. The specific test results are shown in Table 4 below.
[0058] Table 4
[0059] project Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 State within the container After stirring, the mixture is smooth and free of lumps. After stirring, the mixture is smooth and free of lumps. After stirring, the mixture is smooth and free of lumps. After stirring, the mixture is smooth and free of lumps. After stirring, the mixture is smooth and free of lumps. After stirring, the mixture is smooth and free of lumps. After stirring, the mixture is smooth and free of lumps. <![CDATA[Acid resistance / (240 h) 10% HSO4 solution]]> No abnormalities No abnormalities No abnormalities No abnormalities No abnormalities No abnormalities No abnormalities Alkali resistance / (240h) 10% NaOH solution No abnormalities No abnormalities No abnormalities No abnormalities No abnormalities No abnormalities No abnormalities Water resistance / 30d No abnormalities No abnormalities No abnormalities No abnormalities No abnormalities No abnormalities No abnormalities Combustion performance Grade A Grade A Grade A Grade A Grade A Grade A Grade A Coating temperature resistance (10 cycles) No abnormalities No abnormalities No abnormalities No abnormalities No abnormalities No abnormalities No abnormalities Resistivity (Ω) <![CDATA[10 8 ]]> <![CDATA[10 7 ]]> <![CDATA[10 8 ]]> <![CDATA[10 8 ]]> <![CDATA[10 8 ]]> <![CDATA[>10 12 ]]> <![CDATA[>10 12 ]]> Anti-mold properties Level 0 Level 0 Level 0 Level 0 Level 0 Level 0 Level 0 Moist heat resistance / d 7D coating is free from cracking, bubbling, and wrinkling. 7D coating is free from cracking, bubbling, and wrinkling. 7D coating is free from cracking, bubbling, and wrinkling. 7D coating has no cracks, but has blistering and wrinkling. 7D coating has no cracks, but has blistering and wrinkling. 7D coating has no cracks, but has blistering and wrinkling. 7D coating is free from cracking, bubbling, and wrinkling. Freeze-thaw cycle resistance / time After 15 cycles, the coating showed no blistering, wrinkling, or peeling. After 15 cycles, the coating showed no blistering, wrinkling, or peeling. After 15 cycles, the coating showed no blistering, wrinkling, or peeling. After 15 cycles, the coating showed no blistering, wrinkling, or peeling. After 15 cycles, the coating showed no blistering, wrinkling, or peeling. After 15 cycles, the coating showed no blistering, wrinkling, or peeling. After 15 cycles, the coating showed no blistering, wrinkling, or peeling. Stain resistance 6% 5% 6% 6% 6% 11% 12% Reflectivity % 97 98 97 97 96 97 97 Reflectance % after dry powder (fly ash) contamination 96 97 96 96 95 90 91 Solar reflectance 89 90 88 80 88 89 89 Near-infrared reflectance 89 88 90 91 83 89 89 hemispherical emissivity 87 89 88 85 85 87 88 Resistance to artificial aging No bubbling, cracking, or peeling after 1000 hours. No bubbling, cracking, or peeling after 1000 hours. No bubbling, cracking, or peeling after 1000 hours. No bubbling, cracking, or peeling after 1000 hours. No bubbling, cracking, or peeling after 1000 hours. No bubbling, cracking, or peeling after 1000 hours. No bubbling, cracking, or peeling after 1000 hours.
[0060] Reflectance measurement after dry powder (fly ash) contamination: Sprinkle dry fly ash powder on the surface of the dry sample coating, stand the sample upright and shake off the fly ash from the coating surface, and measure the reflectance of the coating surface with a reflectance meter.
[0061] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A radiative cooling and heat insulation coating, characterized in that, The coating comprises a primer and a topcoat. The primer is composed of the following raw materials in parts by weight: 65-75 parts deionized water, 0.1-0.2 parts pH adjuster, 0.2-0.5 parts defoamer, 0.4-0.6 parts hydroxypropyl methylcellulose, 1-1.5 parts wetting agent, 0.4-0.8 parts dispersant, 25-30 parts waterborne polyurethane emulsion, 7-15 parts aerogel, 7-10 parts hollow glass microspheres, 7-8 parts sepiolite, and 3-5 parts film-forming aid. The topcoat is composed of the following raw materials in parts by weight: 25 parts deionized water... -35 parts, pH adjuster 0.1-0.2 parts, defoamer 0.1-0.3 parts, hydroxypropyl methylcellulose 0.2-0.3 parts, dispersant 0.4-0.8 parts, silicon dioxide 2-5 parts, zirconium oxide 3-5 parts, rutile titanium dioxide 10-15 parts, infrared reflective filler 10-16 parts, film-forming aid 2-3 parts, defoamer 0.1-0.2 parts, far-infrared ceramic powder 4-7 parts, potassium silicate 15-19 parts, silica sol 8-12 parts, titanium sol 5-7 parts, silane-modified acrylic emulsion 5-7 parts, conductive mica powder 3-4 parts; The rutile titanium dioxide is DuPont's R-902, and the infrared reflective filler is a mixture of Panhua Chemical's IR-1000 and Panengtuo's W400, with a mass ratio of IR-1000 to W400 of 1:
1. The potassium silicate has a modulus of 3.85-4.35; the silica sol is a silane-modified silica sol. The aqueous polyurethane emulsion is prepared using the following raw materials in the following weight proportions according to the following preparation method: a. Preparation of polyurethane prepolymer: 55 parts of polyester polyol from Huada Chemical were added to the reactor under stirring. The temperature was raised to 70℃ and 65 parts of isoflurane diisocyanate were added. The temperature was raised to 80-85℃ under nitrogen protection and the reaction was continued until the measured -NCO content reached the theoretical value. The rotation speed and temperature were maintained, and 30 parts of acetone, 11 parts of 2,2-dimethylolpropionic acid, and 0.1 parts of dibutyltin dilaurate were added. The reaction was continued until the measured -NCO content reached the theoretical value. 5 parts of 1,4-butanediol were added to the reactor and the reaction was continued until the measured -NCO content reached the theoretical value to obtain the polyurethane prepolymer. b. Neutralization, emulsification and aqueous chain extension of polyurethane prepolymer: Cool to 35℃, add 8 parts of triethanolamine, neutralize for 5 min, then add 180 parts of water, dilute and emulsify for 20 min, dissolve 2.5 parts of ethylenediamine in 30 parts of water, add the ethylenediamine aqueous solution dropwise to the reaction system over 10-15 minutes, and perform the aqueous chain extension reaction for 2 h. Distill off acetone under reduced pressure to obtain an aqueous polyurethane emulsion.
2. The radiative cooling and heat insulation coating according to claim 1, characterized in that, The aerogel is a hydrophobic aerogel powder with a pore size of 20 nm.
3. The radiative cooling and heat insulation coating according to claim 1, characterized in that, The primer contains 4-6 parts of phase change microcapsules, which are prepared from the following raw materials in the following weight proportions according to the following preparation method: 1) Add 50 parts of paraffin wax with a melting point of 37℃, 16 parts of methyl methacrylate, 9 parts of methacrylic acid, 76 parts of deionized water, 1 part of anionic emulsifier, 1 part of nonionic emulsifier and 0.3 parts of initiator azobisisobutyronitrile to an emulsification reactor. Emulsify for 30 minutes at a temperature 5℃ higher than the melting point of paraffin wax and a stirring speed of 800-1200 r / min. Reduce the stirring speed to 300 r / min and heat to 80-85℃ for 3 hours. Then add 1.5 parts of divinylbenzene and react for 3 hours. Cool down to 65℃ and add 0.05 parts of oxidant tert-butyl hydroperoxide and 0.05 parts of reducing agent FF6M alternately in two batches at 5-minute intervals. After the addition is complete, react at 65℃ for 0.5 hours. 2) Cool down to below 45℃, add 1 part ammonia water to neutralize for 10 minutes, filter the obtained phase change microcapsule emulsion, wash with water 2-3 times, and then air dry to obtain phase change microcapsules.
4. The radiative cooling and heat insulation coating according to claim 1, characterized in that, The silane-modified silica sol was prepared by the following method, with the raw materials listed in parts by weight: S1: Add 12.5 parts of tetraethyl orthosilicate and 70 parts of ethanol to a reaction flask under stirring. Heat to 60°C, add 6.5 parts of deionized water, and adjust the pH to 8-9 by adding ammonia dropwise. Stir and react at 60°C for 2 hours. Then add 50 parts of deionized water to dilute, heat to boiling, and reflux to remove ethanol and ammonia, thus obtaining silica sol prepolymer. S2: Cool the silica sol prepolymer to 60℃, add 5.5 parts of tetraethyl orthosilicate, and add ammonia to adjust the pH of the reaction solution to 8-9. React for 3 hours. S3: Add 0.2 parts of KH550 and 0.6 parts of KH560 dropwise to modify the silica sol, react at 60℃ for 1 hour, and then concentrate by distillation at atmospheric pressure to obtain modified silica sol with a solid content of 30%.
5. The radiative cooling and heat insulation coating according to claim 1, characterized in that, The titanium sol is anatase nano-titanium dioxide sol; the silane-modified acrylic emulsion is KRN8101 from Heshan Jinrunna New Material Co., Ltd.
6. A method for preparing a radiative cooling and heat-insulating coating as described in any one of claims 1-5, characterized in that, The primer is prepared by the following method: Step 1: Add deionized water, pH adjuster, defoamer, hydroxypropyl methylcellulose, wetting agent, and dispersant to the reaction vessel, disperse evenly, then add aerogel and stir until the aerogel is evenly dispersed to obtain aerogel slurry; Step 2: Add water-based polyurethane emulsion to the dispersion vessel, and add hollow glass microspheres, sepiolite, film-forming aid, and aerogel slurry while stirring. Stir until uniform to obtain the primer of the radiation cooling and heat insulation coating. The topcoat is prepared by the following method: Deionized water, pH adjuster, defoamer, hydroxypropyl methylcellulose, and dispersant are added to a reaction vessel and stirred at 1800 rpm for 15 minutes. Then, silica, zirconium oxide, rutile titanium dioxide, infrared reflective filler, far-infrared ceramic powder, and conductive mica powder are added and stirred at 1800 rpm for 30 minutes. The stirring speed is then reduced to 600 rpm, and film-forming aids, silane-modified acrylic emulsion, defoamer, potassium silicate, silica sol, and titanium sol are added and stirred until homogeneous to obtain the topcoat of the radiation cooling and heat insulation coating.