Radiation cooling color coating containing functional pigment and preparation method thereof

Abstract

The present application relates to a kind of functional color fillers containing radiation refrigeration color coating and its preparation method.The coating is composed of infrared high emission transparent film-forming resin, near-infrared high reflection functional pigment, core-shell structure infrared radiation filler and additives, solvent.The present application uses functional pigment designed by energy band engineering or surface modification, which shows color in visible light region and the reflectivity of near-infrared band is greater than or equal to 85%, and the core-shell structure filler composed of high infrared emissivity inorganic shell coated hollow glass microspheres.Through the synergistic effect of the above functional components and infrared high emissivity resin in single layer system, high color fidelity, high near-infrared reflectivity and atmospheric window emissivity can be realized at the same time.The present application overturns the traditional "high reflection bottom layer + color topcoat" double-layer structure, and solves the problem that color and high-efficiency radiation refrigeration performance are difficult to be considered at the same time by single-layer coating, which significantly reduces the cost and improves the reliability of coating.

Description

Technical Field

[0001] This invention relates to the field of radiation-cooling coating technology, and in particular to a radiation-cooling colored coating containing functional pigments and fillers and its preparation method, especially to the preparation of a single-layer radiation-cooling colored coating based on the synergistic effect of functional pigments and core-shell structure infrared radiation fillers. Background Technology

[0002] In the field of energy conservation in buildings and industrial equipment, the core function of radiation cooling coatings relies on their high solar reflectivity (Ri). solar ) and high atmospheric window emissivity (ε 8-13μm The synergistic effect of ) . According to the principle of thermodynamic equilibrium, when the coating satisfies R solar ≥80% and ε 8-13μm When the efficiency is ≥90%, heat can be radiated into the low-temperature outer space through the 8-13 μm wavelength band, achieving zero-energy cooling. However, although some studies have attempted to use pigments with certain infrared reflective properties (such as partially infrared reflective pigments) or core-shell structured fillers, simply combining these known materials usually makes it difficult to achieve a perfect balance of wide color gamut, high color saturation, high near-infrared reflectivity (>85%), and high atmospheric window emissivity (>96%) in a single coating. The fundamental reason is that the color rendering mechanism (electron transition absorption) of conventional pigments in the visible light region is often accompanied by the absorption of near-infrared photons; while the infrared emission performance of ordinary fillers is limited, and their interfacial compatibility with resins and pigments is poor, which easily leads to a decline in the optical and mechanical properties of the coating.

[0003] Therefore, developing a coating that achieves synergy between color and extreme radiative cooling performance within a single layer through component and structural innovation still faces technical challenges. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a radiation-cooled colored coating containing functional pigments and fillers and its preparation method. Through the design of unique functional pigments and core-shell structure infrared radiation fillers, and compounding with a high infrared emissivity resin matrix, a radiation-cooled colored coating and a single-layer radiation-cooled colored coating with wide color gamut, high fidelity color, high near-infrared reflectivity and high atmospheric window emissivity are synergistically achieved in a single-layer coating.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a radiation-cooling colored coating containing functional pigments and fillers, which comprises the following components by mass percentage: Infrared high-emission transparent film-forming resin 50%-70%; Near-infrared high reflectance pigments: 5%-30%; Core-shell structure infrared radiation filler 1%-15%; Additives 0.5%-10%; Solvent balance.

[0006] As one embodiment of the present invention, the infrared high-emission transparent film-forming resin is one or more of acrylic resin and silicone resin.

[0007] The infrared-emitting transparent film-forming resin has an infrared emissivity of not less than 0.90 in the 8-13 μm wavelength range. Monomers containing strong infrared absorbing groups (such as COC, Si-O-Si, C=O, NH) are introduced into its molecular chain, or components that help improve the infrared emissivity are introduced through blending / grafting.

[0008] As one embodiment of the present invention, the infrared high reflectance functional pigment is a special pigment that has undergone band engineering design or surface functionalization modification; the special pigment selectively absorbs and displays color in the visible light region, while having an average reflectance of not less than 85% in the 0.78-2.5μm near-infrared band.

[0009] Bandgap engineering design includes one of ion doping and heterostructure construction. Surface functionalization modification includes one of organic coating, inorganic coating, and organic-inorganic composite coating. This invention modifies the electronic bandgap structure through ion doping, heterostructure construction, or organic-inorganic composite coating, narrowing its color absorption band and blue-shifting it into the visible light region, thereby maximizing the preservation of high reflectivity in the near-infrared band.

[0010] Conventional pigments used in colored coatings (such as iron oxide red and carbon black) have a reflectance of less than 40% in the near-infrared band, and direct use would lead to the loss of cooling function. This invention achieves "color-high reflectance decoupling" through spectrally designed composite metal oxides, breaking through the conventional understanding that colored materials must have low reflectance.

[0011] As one embodiment of the present invention, the near-infrared high reflectance pigment is a modified high reflectance pigment, or a combination of a modified high reflectance pigment and a conventional high reflectance pigment; The modified high-reflectivity pigment includes one or more of high-reflectivity yellow pigment, high-reflectivity black pigment, and high-reflectivity red pigment; The conventional high-reflectivity pigments include high-reflectivity white pigments.

[0012] Preferably, the high-reflectivity black pigment is a black pigment in situ coated with hyperbranched polyesteramine. The black pigment is CuCr2O4 (spinel-type composite metal oxide). The high-reflectivity black pigment is a modified spinel-type composite metal oxide (such as CuCr2O4@HBP). This coating layer can passivate the surface states of the pigment, reduce the absorption of near-infrared photons by free carriers, and enhance its dispersion stability in the resin.

[0013] Existing high-reflectivity pigments (especially black pigment CuCr2O4) can cause reflectivity reduction (reflectivity >20%) and color deviation (ΔE*) when used in colored coatings. ab >3), through a pre-modification step, the present invention uses hyperbranched polymer (HBP) coating and controls D90≤5μm after grinding. The uniform hyperbranched polyesteramine coating layer can improve the surface roughness of the particles, reduce irregular light absorption caused by surface defects, and effectively improve the overall reflectivity, significantly improve its reflectivity in colored coatings, and ensure reflectivity ≥85% and ΔE*ab≤0.5.

[0014] The black pigment in situ coated with hyperbranched polyesteramine was prepared by the following method: The black pigment was ultrasonically dispersed in a solvent, hyperbranched polyesteramine was added, the mixture was stirred and reacted, and then centrifuged to obtain the black pigment coated in situ with hyperbranched polyesteramine. The black pigment is CuCr2O4; The solvent is ethanol; The hyperbranched polyesteramine is an amino-terminated hyperbranched polyesteramine (HBP-NH2); the degree of branching (DB) is 0.4-0.6.

[0015] The ratio of CuCr2O4 to solvent is (8-12) g : (150-300) mL; The mass ratio of CuCr2O4 to hyperbranched polyesteramine is (3-6):1; The ultrasonic dispersion time is 25-40 minutes; The temperature for stirring the reaction is 50-70℃, and the time is 4-8 hours; The products separated by centrifugation are also washed and vacuum dried.

[0016] Preferably, the high-reflectance yellow pigment is a rare earth ion (such as Y). 3+ La 3+ Modified bismuth-vanadium oxide complex (BiVO4 / Bi2O3). Rare earth ions include Y. 3+ La 3+ One or more of the following. Y 3+ La 3+ It will not affect the color of the pigment. This invention optimizes the crystal structure of yellow pigment through doping, reducing the capture of near-infrared photons by lattice defects.

[0017] Rare earth ion modified bismuth vanadium oxide complex (BiVO4 / Bi2O3) was prepared by the following method: Bi... 3+ Solutions and solutions containing VO3 -The solutions are mixed and the pH is adjusted to 7-9, resulting in a yellow precipitate. Rare earth dopant sources are then added, and a hydrothermal reaction is carried out to obtain rare earth ion modified bismuth vanadium oxide complex (BiVO4 / Bi2O3).

[0018] The molar ratio of Bi to V is 1:1-1.2. (This refers to a product containing Bi.) 3+ The solution concentration is 0.1-1 mol / L. Contains Bi. 3+ The solution is obtained by dissolving Bi(NO3)3·5H2O in dilute nitric acid. It contains VO3. - The solution concentration is 0.08-0.12 mol / L. It contains VO3. - The solution was obtained by dissolving NH4VO3 in deionized water and heating (60°C).

[0019] The rare earth doping source includes one or more of Y(NO3)3 and La(NO3)3. The doping amount of rare earth elements is 1-5% of the molar amount of Bi.

[0020] The hydrothermal reaction is carried out at a temperature of 180-220 ℃ for 12-24 h.

[0021] After hydrothermal reaction, the mixture was cooled, filtered, washed with deionized water until neutral, dried (80-100℃, 8-12h), and then ground to obtain rare earth ion modified bismuth vanadium oxide complex (BiVO4 / Bi2O3).

[0022] The high-reflectance red pigment is ytterbium / erbium co-doped iron oxide (Yb / Er-Fe2O3). This invention utilizes the localized field effect of doped ions to modulate the light absorption characteristics of the red pigment.

[0023] Ytterbium / erbium co-doped iron oxide (Yb / Er-Fe2O3) was prepared by the following method: containing Yb 3+ Solutions and containing Er 3+ Add Fe to solution 3+ In the solution, the pH was adjusted to 9-11, and a reddish-brown precipitate was produced. After aging, the precipitate was filtered, dried, and calcined to obtain yttrium / erbium co-doped iron oxide (Yb / Er-Fe2O3).

[0024] Contains Yb 3+ The solution is Yb(NO3)3; containing Er 3+ The solution is Er(NO3)3 solution; Fe 3+ The solution is Fe(NO3)3 solution.

[0025] Yb 3+ Doping amount is Fe 3+ 1-5% of molar weight; Er 3+ Doping amount is Fe 3+ 0.5-3% in molar weight. Fe3+ The concentration of the solution is 0.1-0.5 mol / L.

[0026] To adjust the pH to 9-11, NaOH solution (1 mol / L) is added dropwise, resulting in a reddish-brown precipitate.

[0027] The aging time is 2-4 hours. The filtered product is washed with deionized water until neutral. The drying temperature is 80-100℃ and the drying time is 8-12 hours.

[0028] The calcination temperature is 400-600℃, and the time is 2-4 hours. The dried product is ground and then calcined again. After calcination and cooling, it is ground and sieved again to obtain the modified red pigment.

[0029] The high-reflectivity white pigment is titanium dioxide.

[0030] When the radiation-cooled colored coating is a yellow-green coating, the near-infrared high-reflectivity pigment includes high-reflectivity yellow pigment, high-reflectivity black pigment, and high-reflectivity white pigment.

[0031] When the radiation-cooled colored coating is a military green coating, the near-infrared high-reflectivity pigment includes high-reflectivity yellow pigment, high-reflectivity black pigment, and high-reflectivity white pigment.

[0032] When the radiation-cooled colored coating is a yellowish-brown coating, the near-infrared high-reflectivity pigment includes high-reflectivity yellow pigment, high-reflectivity red pigment, and high-reflectivity black pigment.

[0033] When the radiation-cooled colored coating is a deep yellow coating, the near-infrared high-reflectivity pigment includes high-reflectivity yellow pigment, high-reflectivity black pigment, and high-reflectivity white pigment.

[0034] When the radiation-cooled colored coating is a wine-red coating, the near-infrared high-reflectivity pigment includes high-reflectivity white pigment, high-reflectivity red pigment, and high-reflectivity black pigment.

[0035] When the radiation-cooled colored coating is a brick-red coating, the near-infrared high-reflectivity pigment includes high-reflectivity white pigment, high-reflectivity red pigment, and high-reflectivity black pigment.

[0036] In one embodiment of the present invention, the core of the core-shell structure infrared radiation filler is a hollow glass microsphere and the shell is BN.

[0037] As one embodiment of the present invention, the core-shell structure infrared radiation filler is prepared by the following method: Hollow glass microspheres were dispersed in an aqueous-ethanol solution containing triethyl borate and urea to form a sol. The sol was then gelled on the surface of the microspheres under constant temperature stirring. The product was then calcined in an ammonia atmosphere to obtain a core-shell structured infrared radiation filler.

[0038] The mass ratio of the hollow glass microspheres, triethyl borate, and urea is 20:(3-5):(1-2).

[0039] The particle size D50 of the glass microspheres is 15-95 μm.

[0040] The water-ethanol solution contains 0.15-0.25 mol / L of triethyl borate and 0.3-0.5 mol / L of urea; the volume ratio of water to ethanol is 3:7.

[0041] The constant temperature stirring is 40-50℃, the time is 2-4 hours, and the speed is 300-500 rpm.

[0042] After constant temperature stirring, the mixture is aged for 10-14 hours. Following aging, it is centrifuged, and the precipitate is collected and washed 3-5 times with deionized water to remove residual urea and ethanol. The washed precipitate is then placed in a vacuum drying oven and dried at 75-85℃ for 10-14 hours.

[0043] The calcination temperature is 700-900℃, and the time is 2-4 hours. The heating rate during calcination is 4-6℃ / min.

[0044] The shell thickness of the obtained core-shell structure infrared radiation filler is 1-1.5 μm.

[0045] Another key improvement of this invention is that the core-shell structured infrared radiation filler is characterized by a composite structure of a "hollow glass microsphere core" and a "high infrared emissivity inorganic shell." This structural design brings unexpected technical effects: Lightweight and heat-insulating: The hollow glass microsphere core reduces the density of the filler and introduces an air insulation layer, reducing heat conduction.

[0046] High infrared emissivity: The selected BN shell material has a high intrinsic emissivity (>0.90) in the 8-13 μm band, and the shell coating ensures that the filler surface has continuous and uniform high emissivity.

[0047] Structural enhancement and scattering optimization: Compared with powders that are simply physically mixed, core-shell structures can form a more stable three-dimensional network in coatings, enhancing the mechanical properties of the coatings; at the same time, their size and morphology can be adjusted, which helps to optimize light scattering inside the coating and reduce light loss.

[0048] The shell layer is formed in situ on the surface of hollow glass microspheres using a sol-gel method, ensuring the bonding strength and uniformity between the shell layer and the core. The infrared radiation filler of the core-shell structure has an infrared emissivity of not less than 0.92 in the 8-13 μm wavelength band.

[0049] As one embodiment of the present invention, the additives include one or more of dispersants, leveling agents, and defoamers.

[0050] The dispersant is one or more of polyacrylate dispersants (such as BYK-180) and polyether-modified polysiloxane dispersants.

[0051] The leveling agent is one or more of the following: polyether-modified polysiloxane leveling agent (such as BYK-333) and acrylate leveling agent.

[0052] The defoamer is one or more of the following: modified polysiloxane defoamers (such as BYK-054) and mineral oil defoamers.

[0053] In one embodiment of the present invention, the solvent is xylene.

[0054] The core concept of this invention lies in dispersing the aforementioned specially designed near-infrared high-reflectivity functional pigments and infrared radiation fillers with unique core-shell structures within a transparent resin matrix with high infrared emissivity. Within a single-layer coating, the three components work synergistically: the functional pigments reflect the vast majority of near-infrared heat from sunlight; the resin matrix and the shell of the core-shell filler together form a highly efficient infrared radiation network, radiating heat away through atmospheric windows; the hollow structure of the core-shell filler and the optimization of the overall formulation ensure that the coating achieves excellent optical and thermal properties even at relatively thin thicknesses (20-100 μm), thus overcoming the technical bottlenecks of the difficulty in achieving compatibility between "high reflectivity" and "high color rendering" in a single layer, and the tendency of "high-emissivity" fillers to affect the physicochemical properties of the coating.

[0055] Secondly, the present invention provides a method for preparing the radiation-cooled colored coating containing functional pigments and fillers, comprising the following steps: S1, Pigment pre-dispersion: A portion of acrylic resin, near-infrared high-reflectance pigment, core-shell structure infrared radiation filler, a portion of dispersant, and a portion of solvent are pre-dispersed at high speed to obtain a uniform premixed slurry. S2, Grinding and refining: The premixed slurry is ground until the particle size D90 of the pigment particles in the slurry is ≤1.8 μm to obtain a fine and uniform color paste; S3, Coating Preparation: The obtained color paste, the remaining acrylic resin, leveling agent, defoamer, remaining dispersant, and remaining solvent are mixed, stirred, and then filtered to obtain the single-layer radiation-cooled colored coating.

[0056] In step S1, the additives include dispersants, leveling agents, and defoamers.

[0057] In step S1, "partial acrylic resin" refers to 55-70% of the total mass of acrylic resin.

[0058] In step S1, "partial dispersant" refers to 75-85% of the total mass of the dispersant.

[0059] In step S1, "partial solvent" refers to 45-55% of the total solvent mass.

[0060] In step S1, the high-speed pre-dispersion speed is 1200-1800 rpm and the time is 25-35 minutes.

[0061] In step S3, the stirring speed is 800-1000 rpm and the time is 1-1.5 hours.

[0062] In step S1, filtration is performed using a 200-300 mesh sieve.

[0063] Thirdly, the present invention provides a single-layer radiation-cooled colored coating prepared from the above-mentioned coating. Its dry film thickness is 20-100 μm.

[0064] Coating preparation: The coating is sprayed onto the surface of the substrate and cured and dried at room temperature (25±2℃) for 40-60 hours to form a dry film, thus obtaining the single-layer radiation cooling colored coating.

[0065] The single-layer radiation-cooled color coating satisfies the following optical properties: Solar reflectance (Ri) in the 0.78–2.5 μm near-infrared band NIR ≥85%; Infrared emissivity (ε) in the 8-13 μm atmospheric window band 8-13μm ≥96%.

[0066] Furthermore, the color difference value ΔE* between the single-layer radiation-cooled color coating and the standard color card is... ab ≤0.5, thus ensuring color accuracy.

[0067] Compared with the prior art, the present invention has the following beneficial effects: (1) This invention abandons the traditional double-layer structure and can form a decorative effect (ΔE*) with a single coating. ab ≤ 0.5) and high-efficiency radiative cooling performance (R NIR ≥ 85%, ε 8-13μm The coating (≥ 96%) significantly reduces costs, simplifies construction, and completely avoids interlayer adhesion problems.

[0068] (2) The near-infrared high reflectance functional pigment used in this invention achieves the decoupling of "visible light color rendering" and "near-infrared high reflectance" through band engineering or surface modification. This is something that conventional pigments cannot achieve, and solves the fundamental problem of low near-infrared reflectance of colored coatings.

[0069] (3) By introducing a unique core-shell structure infrared radiation filler, the present invention not only has a high infrared emissivity, but its lightweight hollow core and shell structure also brings additional benefits such as heat insulation, enhancement and optimization of light scattering, and better compatibility with resin matrix, thus achieving a synergistic radiation cooling effect of 1+1>2.

[0070] (4) The present invention produces an unexpected synergistic enhancement effect by combining functional pigments, core-shell fillers and high-emissivity resins in a single-layer system. Experiments show that the coating using the specific combination of the present invention achieves a high level of both near-infrared reflectivity and mid-infrared emissivity, which significantly exceeds the theoretical superposition value that can be achieved using conventional infrared reflective pigments or ordinary core-shell fillers, proving the non-obviousness of the present invention. Attached Figure Description

[0071] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a schematic diagram of the structure of the single-layer radiation-cooled color coating of the present invention. Detailed Implementation

[0072] To more clearly illustrate the present invention, the following description, in conjunction with preferred embodiments, further clarifies the invention. Those skilled in the art should understand that the specific descriptions below are illustrative rather than restrictive, and should not be construed as limiting the scope of protection of the present invention.

[0073] The raw materials used in this invention are prepared as follows: Film-forming resin 1: Organosilicon resin (ε 8-13μm =0.95, SR109H, Shanghai Aishibo); Film-forming resin 2: Acrylic resin (ε 8-13μm =0.92, BR-115, Mitsubishi, Japan); Film-forming resin 3: Epoxy resin (ε 8-13μm =0.80, E51, Baling Petrochemical); White pigment: Rutile titanium dioxide (particle size 0.3-1 μm, R NIR >95%) White pigment 2: Alumina (particle size 0.5-1μm, R) NIR >83%); Black Pigment 1: Hyperbranched Polyesteramine-Coated CuCr2O4 (Black Pigment CuCr2O4@HBP, R) NIR >85%), preparation method: (1) Disperse 10g of CuCr2O4 spinel powder (particle size 0.2-0.5 μm) in 200mL of ethanol and ultrasonically disperse for 30 minutes to form a uniform suspension; (2) Add 2g of terminal amino hyperbranched polyesteramine (HBP-NH2, model ED900, branching degree (DB) of 0.5) to the above suspension and stir until homogeneous; (3) Heat the reaction system to 60°C and react for 6 hours under magnetic stirring; (4) After the reaction is complete, the product is centrifuged and the precipitate is collected; (5) Wash the precipitate three times with ethanol to remove unreacted HBP-NH2; (6) The washed product was vacuum dried at 80°C for 12 hours to obtain CuCr2O4@HBP near-infrared high reflectance black pigment; Tests showed that the near-infrared reflectance of the near-infrared high-reflectance black pigment increased from 70% of the raw material CuCr2O4 to over 85%. Black Pigment 2: Polyesteramine-coated CuCr2O4, the preparation method is basically the same as that of Black Pigment 1, the difference is that the coating material used is alcohol-soluble polyurethane (U230). Black pigment 3: CuCr2O4 (unmodified); Yellow Pigment 1: Transformed with rare earth ions Y 3+ Modified bismuth vanadium oxide complex (yellow pigment Y-BiVO4 / Bi2O3, R) NIR >90%), preparation method: (1) Take 0.01 mol (4.8507 g) Bi(NO3)3·5H2O, dissolve it in 50 mL of 0.5 mol / L dilute nitric acid, and obtain Bi 3+ Solution; (2) Take 0.01 mol (1.1698 g) of NH4VO3 and dissolve it in 100 mL of deionized water at 60℃ to obtain VO3. - Solution; (3) Change Bi 3+ Solution and VO3 - Mix the solutions thoroughly; add 1 mol / L NaOH solution dropwise to adjust the pH to 8, resulting in a yellow precipitate. (4) Add Y(NO3)3·6H2O, with a doping amount of 3 mol% (relative to Bi). 3+ (i.e., 0.1386 g). (5) Transfer the suspension to a hydrothermal reactor and react at 200°C for 18 h; (6) After cooling, filter and wash with deionized water until neutral; (7) Dry at 90℃ for 10 h, then grind to obtain Y 3+ Doped BiVO4 / Bi2O3 yellow pigment (particle size 0.5-1 μm); Yellow Pigment 2: Contains rare earth ions Ce 3+ The modified bismuth-vanadium oxide complex was prepared in a manner that was basically the same as that of yellow pigment 1, except that γ(NO3)3·6H2O was replaced with an equimolar amount of Ce(NO)3·6H2O. Yellow pigment 3: processed with Cr 3+ The modified bismuth-vanadium oxide complex was prepared in a manner that was basically the same as that of yellow pigment 1, except that Cr(NO3)3·6H2O was replaced with an equimolar amount of Cr(NO3)3·9H2O. Red Pigment 1: Ytterbium / Er-Fe2O3 co-doped iron oxide (Red Pigment Yb / Er-Fe2O3, R NIR >85%), preparation method: (1) Weigh 40.4 g (0.1 mol) Fe(NO3)3·9H2O according to the stoichiometric ratio, dissolve it in 500 mL of deionized water, and prepare a solution with a concentration of 0.2 mol / L; (2) Add 0.467 g Yb(NO3)3·6H2O (0.001 mol, doping amount 1 mol%, relative to Fe) 3+ ) and 0.2305 g Er(NO3)3·6H2O (0.0005 mol, doping amount 0.5 mol%, relative to Fe 3+ Stir until completely dissolved; (3) After stirring evenly, add 1 mol / L NaOH solution dropwise to adjust the pH to 10, and a reddish-brown precipitate will be produced; (4) Let the sediment age for 3 hours, filter, and collect the filter cake; (5) Wash the filter cake repeatedly with deionized water until the washing liquid is neutral; (6) Dry the filter cake at 90℃ for 10 hours; (7) After grinding into powder, transfer to a muffle furnace and calcine at 500°C for 3 hours; (8) After cooling, remove and grind, then sieve (200 mesh) to obtain Yb. 3+ / Er 3+ Fe2O3 co-doped modified red pigment (particle size 0.2-1 μm).

[0074] Red Pigment 2: Ytterbium-doped iron oxide, prepared in a method basically the same as Red Pigment 1, except that only Yb(NO3)3·6H2O is used for doping, with a doping amount of 1.5 mol%; Red Pigment 3: Erbium-doped iron oxide, prepared in a method basically the same as Red Pigment 1, except that only Er(NO3)3·6H2O is used for doping, with a doping amount of 1.5 mol%; Red pigment 4: Ce 3+ The preparation method of doped iron oxide is basically the same as that of red pigment 1, except that Yb(NO3)3·6H2O is replaced with an equimolar amount of Ce(NO)3·6H2O. Infrared radiation filler 1: Preparation of boron nitride-coated hollow glass microspheres by sol-gel method (infrared radiation filler HGM@BN, ε 8-13μm =0.96); Preparation method: (1) Preparation of precursor solution: Take 4g of triethyl borate and 1.5g of urea, dissolve them in a water-ethanol mixed solvent (90 mL of deionized water and 210 mL of anhydrous ethanol, volume ratio 3:7), and stir until completely dissolved to form a homogeneous precursor solution. The concentration of triethyl borate is approximately 0.2 mol / L, and the concentration of urea is approximately 0.4 mol / L.

[0075] (2) Dispersion of hollow glass microspheres: Take 20g of hollow glass microspheres (HGM, D50=55 μm) and add them to the above precursor solution. Disperse them by ultrasonication for 30 minutes at room temperature to make them uniformly dispersed.

[0076] (3) Sol-gel process: The dispersed suspension is transferred to a three-necked flask equipped with a mechanical stirring and temperature control device. The flask is stirred on a constant temperature magnetic stirrer at a temperature of 45°C and a speed of 400 rpm for 3 hours to allow the sol to gradually gel on the surface of the hollow glass microspheres and form a uniform coating layer.

[0077] (4) Aging and washing: The suspension after reaction is aged for 12 hours, then centrifuged to collect the precipitate, and washed with deionized water 3-5 times to remove residual urea and ethanol.

[0078] (5) Drying: The washed precipitate was placed in a vacuum drying oven and dried at 80°C for 12 hours to obtain hollow glass microsphere powder coated with precursor.

[0079] (6) Calcination: The dried powder is placed in a muffle furnace for calcination. The temperature is increased to 800°C at a rate of 5°C / min, held for 2 hours, and then naturally cooled to room temperature.

[0080] (7) Post-processing: The calcined product was ground and sieved (200 mesh) to obtain BN@HGM core-shell structure infrared radiation filler with a coating thickness of 1.3 μm; Infrared radiation filler 2: Titanium oxide coated hollow glass microspheres (HGM@TiO2); Preparation method: Ceramic hollow microspheres (HGM, D50=55 μm) were soaked in a titanium sulfate aqueous solution (58 parts titanium sulfate added to 500 parts industrial tap water) and the pH was adjusted to 10 with sodium hydroxide. Sodium silicate was added and stirred for 30 minutes after thorough mixing. The pH was then adjusted to 4 and magnesium chloride and aluminum chloride were added in sequence. The mixture was stirred at 60 rpm for 60 minutes while being ultrasonically vibrated. The pH was then neutralized to 7 with sodium hydroxide and stirred for another 60 minutes. After filtration, washing, and drying, the mixture was transferred to a high-temperature resistant container and calcined in a high-temperature resistance furnace at 400℃ for 4 hours. The temperature was then increased to 600℃ and calcined for 2 hours. The mixture was then removed from the furnace and allowed to cool naturally to obtain coated ceramic hollow microspheres with a coating thickness of 1.3 μm. Dispersant: BYK-180; Leveling agent: BYK-333; Defoamer: BYK-054; Solvent: Xylene.

[0081] Example 1: Preparation and performance of a single-layer yellow-green cooling coating (1) Raw materials and formula: As shown in Table 1, prepare the components of the coating by mass percentage; (2) Preparation method: The specific steps are as follows: (a) Pigment pre-dispersion: Weigh approximately 40% of the total amount of acrylic resin (approximately 63.5% of the total resin), all near-infrared high reflectance pigments (rutile titanium dioxide, CuCr2O4@HBP black pigment, Y-BiVO4 / Bi2O3 yellow pigment), HGM@BN infrared radiation filler, dispersant (0.8% of the total amount), and a portion of xylene (approximately 8% of the total amount), and place them in a dispersion tank. Pre-disperde at high speed of 1500 rpm for 30 minutes to obtain a uniform premixed slurry.

[0082] (b) Grinding and refining: The premixed slurry from step (a) is transferred to a sand mill and ground until the particle size D90 of the pigment particles in the slurry is ≤ 1.8 μm, so as to obtain a fine and uniform color paste.

[0083] (c) Coating preparation: The color paste obtained in step (b), the remaining acrylic resin (approximately 36.5% of the total resin), leveling agent, defoamer, remaining dispersant (0.2%), and remaining xylene (approximately 7.5% of the total) are mixed and stirred at 900 rpm for 1 hour to ensure thorough mixing. The mixture is then filtered through a 200-mesh sieve to obtain the single-layer radiative cooling colored coating.

[0084] (d) Coating and curing: The above coating is uniformly applied to the clean tinplate substrate surface using air spraying. Figure 1 The wet film thickness was controlled. Subsequently, it was cured and dried at room temperature (25±2℃) for 48 hours to form a single-layer radiation-cooled colored coating with a dry film thickness of approximately 45 μm.

[0085] (3) Performance test and results The resulting coating was subjected to performance testing: Color performance: Measured using a colorimeter, the coating's chromaticity values ​​are L=40.9, a*=-5.3, b*=12.7, and the color difference value ΔE* between the coating and the target yellow-green standard color chart is... ab =0.12, high color fidelity.

[0086] Optical performance: The near-infrared reflectance R of the coating in the 0.78-2.5 μm band was measured using a UV-Vis-NIR spectrophotometer and a Fourier transform infrared spectrometer. NIR =88.7%, infrared emissivity ε in the 8-13 μm band 8-13μm =96.5%.

[0087] Cooling effect: Under a standard solar simulator (irradiance 1000 W / m²), the temperature difference between the inner and outer surfaces of the coating was tested, and the cooling temperature difference reached 10.9℃.

[0088] Comparative Example 1 The composition and preparation method of this comparative example are basically the same as those of Example 1, except that film-forming resin 2 is replaced with film-forming resin 3.

[0089] Comparative Example 2 The composition and preparation method of this comparative example are basically the same as those of Example 1, except that white pigment 1 is replaced with white pigment 2.

[0090] Comparative Example 3 The composition and preparation method of this comparative example are basically the same as those of Example 1, except that black pigment 1 is replaced with black pigment 2.

[0091] Comparative Example 4 The composition and preparation method of this comparative example are basically the same as those of Example 1, except that black pigment 1 is replaced with black pigment 3.

[0092] Comparative Example 5 The composition and preparation method of this comparative example are basically the same as those of Example 1, except that infrared radiation filler 1 is replaced with infrared radiation filler 2.

[0093] Table 1: Comparison of the formulations of Example 1 and Comparative Examples 1-5

[0094] Example 2: Preparation and performance of a single-layer ochre-colored cooling coating (1) Raw materials and formula, as shown in Table 2, prepare each component of the coating by mass percentage; (2) The preparation method is the same as in Example 1; (3) Performance test and results The resulting coating was subjected to performance testing: Color performance: Measured using a colorimeter, the coating's chromaticity values ​​are L=52.3, a*=3.2, b*=18.7, and the color difference value ΔE* between this coating and the target ochre standard color chart is... ab =0.15, high color fidelity.

[0095] Optical performance: The near-infrared reflectance R of the coating in the 0.78-2.5 μm band was measured using a UV-Vis-NIR spectrophotometer and a Fourier transform infrared spectrometer. NIR =87.5%, infrared emissivity ε in the 8-13 μm band 8-13μm =97%.

[0096] Cooling effect: Under a standard solar simulator (irradiance 1000 W / m²), the temperature difference between the inner and outer surfaces of the coating was tested, and the cooling temperature difference reached 10.2℃.

[0097] Comparative Example 6 The composition and preparation method of this comparative example are basically the same as those of Example 1, except that yellow pigment 1 is replaced with yellow pigment 2.

[0098] Comparative Example 7 The composition and preparation method of this comparative example are basically the same as those of Example 1, except that yellow pigment 1 is replaced with yellow pigment 3.

[0099] Table 2: Comparison of the formulations of Example 2 and Comparative Examples 6-7

[0100] Example 3: Preparation and performance of a single-layer brick-red cooling coating (1) Raw materials and formula, as shown in Table 3, prepare each component of the coating by mass percentage; (2) The preparation method is the same as in Example 1; (3) Performance test and results The resulting coating was subjected to performance testing: Color performance: Measured using a colorimeter, the coating's chromaticity values ​​are L=35.6, a*=18.2, b*=8.9, and the color difference value ΔE* between this coating and the target brick red standard color chart is... ab =0.11, high color fidelity.

[0101] Optical performance: The near-infrared reflectance R of the coating in the 0.78-2.5 μm band was measured using a UV-Vis-NIR spectrophotometer and a Fourier transform infrared spectrometer. NIR =87.3%, infrared emissivity ε in the 8-13 μm band 8-13μm =97.2%.

[0102] Cooling effect: Under a standard solar simulator (irradiance 1000 W / m²), the temperature difference between the inner and outer surfaces of the coating was tested, and the cooling temperature difference reached 10.5℃.

[0103] Comparative Example 8 The composition and preparation method of this comparative example are basically the same as those of Example 1, except that red pigment 1 is replaced with red pigment 2.

[0104] Comparative Example 9 The composition and preparation method of this comparative example are basically the same as those of Example 1, except that red pigment 1 is replaced with red pigment 3.

[0105] Comparative Example 10 The composition and preparation method of this comparative example are basically the same as those of Example 1, except that red pigment 1 is replaced with red pigment 4.

[0106] Table 3: Comparison of the formulations of Example 3 and Comparative Examples 8-10

[0107] The test results of the coatings prepared in the examples and comparative examples are shown in Table 4 below: Table 4: Performance Comparison of Examples and Comparative Examples

[0108] Conclusion: Examples 1-3 simultaneously achieved the highest R... NIR and ε 8-13μm Furthermore, it provides optimal cooling effect and adhesion. Comparative Examples 1-10 demonstrate that ordinary pigments and fillers cannot reproduce the comprehensive and superior performance achieved by the synergistic combination of "special functional pigments + core-shell structure fillers + high-emission resin" of this invention. This fully illustrates the non-obviousness and inventiveness of the technical solution of this invention.

[0109] The above-described specific implementations can be partially adjusted by those skilled in the art in different ways without departing from the principles and purpose of the present invention. The scope of protection of the present invention is defined by the claims and is not limited to the above-described specific implementations. All implementation schemes within the scope of the claims are bound by the present invention.

Claims

1. A radiation-cooling colored coating containing functional pigments and fillers, characterized in that, It comprises the following components by mass percentage: Infrared high-emission transparent film-forming resin 50%-70%; Near-infrared high reflectance pigments: 5%-30%; Core-shell structure infrared radiation filler 1%-15%; Additives 0.5%-10%; Solvent balance; The near-infrared high reflectance pigment is a modified high reflectance pigment, or a combination of a modified high reflectance pigment and a conventional high reflectance pigment; The modified high-reflectivity pigment includes one or more of high-reflectivity yellow pigment, high-reflectivity black pigment, and high-reflectivity red pigment; the conventional high-reflectivity pigment includes high-reflectivity white pigment. The high-reflectivity black pigment is a black pigment in situ coated with hyperbranched polyesteramine; The high-reflectance yellow pigment is a rare-earth ion modified bismuth-vanadium oxide complex; the rare-earth ion is Y. 3+ La 3+ One or more of the following; The high-reflectance red pigment is ytterbium / erbium co-doped iron oxide; The high-reflectivity white pigment is titanium dioxide; The infrared high-emission transparent film-forming resin is one or more of acrylic resin and silicone resin; The core of the core-shell structured infrared radiation filler is a hollow glass microsphere, and the shell is boron nitride.

2. The radiation-cooling colored coating containing functional pigments and fillers according to claim 1, characterized in that, The black pigment coated in situ with hyperbranched polyesteramine is prepared by the following method: the black pigment is ultrasonically dispersed in a solvent, hyperbranched polyesteramine is added, the mixture is stirred and reacted, and then centrifuged to obtain the black pigment coated in situ with hyperbranched polyesteramine.

3. The radiation-cooling colored coating containing functional pigments and fillers according to claim 1, characterized in that, Rare earth ion modified bismuth vanadium oxide complexes are prepared by the following method: Bi... 3+ Solutions and solutions containing VO3 - The solutions are mixed and the pH is adjusted to 7-9, resulting in a yellow precipitate. Rare earth dopant sources are then added, and a hydrothermal reaction is carried out to obtain a rare earth ion-modified bismuth-vanadium oxide complex.

4. The radiation-cooling colored coating containing functional pigments and fillers according to claim 1, characterized in that, Ytterbium / erbium co-doped iron oxide was prepared by the following method: Yb-containing iron oxide was prepared by... 3+ Solutions and containing Er 3+ Add Fe to solution 3+ In the solution, the pH is adjusted to 9-11, and a reddish-brown precipitate is produced. After aging, it is filtered, dried, and calcined to obtain yttrium / erbium co-doped iron oxide.

5. The radiation-cooling colored coating containing functional pigments and fillers according to claim 1, characterized in that, When the radiation-cooled colored coating is a yellow-green coating, the near-infrared high-reflectivity pigment includes high-reflectivity yellow pigment, high-reflectivity black pigment, and high-reflectivity white pigment; When the radiation-cooled colored coating is a military green coating, the near-infrared high-reflectivity pigment includes high-reflectivity yellow pigment, high-reflectivity black pigment, and high-reflectivity white pigment; When the radiation-cooled colored coating is a yellowish-brown coating, the near-infrared high-reflectivity pigment includes high-reflectivity yellow pigment, high-reflectivity red pigment, and high-reflectivity black pigment; When the radiation-cooled colored coating is a deep yellow coating, the near-infrared high-reflectivity pigment includes high-reflectivity yellow pigment, high-reflectivity black pigment, and high-reflectivity white pigment; When the radiation-cooled colored coating is a wine-red coating, the near-infrared high-reflectivity pigment includes high-reflectivity white pigment, high-reflectivity red pigment, and high-reflectivity black pigment; When the radiation-cooled colored coating is a brick-red coating, the near-infrared high-reflectivity pigment includes high-reflectivity white pigment, high-reflectivity red pigment, and high-reflectivity black pigment.

6. The radiation-cooling colored coating containing functional pigments and fillers according to claim 1, characterized in that, The core-shell structured infrared radiation filler was prepared by the following method: hollow glass microspheres were dispersed in a water-ethanol solution containing triethyl borate and urea to form a sol. The sol was gelled on the surface of the microspheres under constant temperature stirring. The product was then calcined in an ammonia atmosphere to obtain the core-shell structured infrared radiation filler.

7. A method for preparing a radiation-cooled colored coating containing functional pigments and fillers as described in claim 1, characterized in that, Includes the following steps: S1, Pigment pre-dispersion: A portion of acrylic resin, near-infrared high-reflectance pigment, core-shell structure infrared radiation filler, a portion of dispersant, and a portion of solvent are pre-dispersed at high speed to obtain a uniform premixed slurry. S2, Grinding and refining: The premixed slurry is ground to obtain a fine and uniform color paste; S3, Coating Preparation: The obtained color paste, the remaining acrylic resin, leveling agent, defoamer, remaining dispersant and remaining solvent are mixed, stirred and filtered to obtain the radiation-cooled colored coating containing functional pigments and fillers.

8. A single-layer radiation-cooled colored coating, characterized in that, It is prepared from the radiation-cooled colored coating as described in claim 1.

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