Inorganic pigment-based colored radiation cooling coated fabric and preparation method thereof

Abstract

The invention discloses an inorganic pigment-based colored radiation cooling coated fabric which comprises a fiber fabric, and a daytime passive radiation coating and a modified inorganic pigment coating which are sequentially coated on the surface of the fiber fabric, the daytime passive radiation coating is an inorganic nano particle coating; the particle size distribution of the inorganic nanoparticles is nanoscale, the sunlight reflectivity of the inorganic nanoparticles is more than 90%, and the mid-infrared radiance of the inorganic nanoparticles is more than 85%; the preparation method of the modified inorganic pigment comprises the following steps: ball-milling an inorganic pigment, adding the ball-milled inorganic pigment into an organic solvent, adding an inorganic non-metallic material, uniformly mixing, standing, taking an upper-layer solution, and drying to obtain inorganic non-metallic microspheres of which the surfaces are adsorbed with the inorganic pigment; and calcining the inorganic nonmetal microspheres with the inorganic pigment adsorbed on the surfaces to obtain the modified inorganic pigment. The problems that in the prior art, a radiation cooling coating is monotonous in color, complex in preparation method, high in cost and the like are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of passive radiation cooling materials, and in particular to an inorganic pigment-based colored radiation cooling coating fabric and a preparation method thereof. Background Art

[0002] Traditional refrigeration consumes a lot of energy and produces a lot of emissions, exacerbating the greenhouse effect and energy crisis. A solution is urgently needed. Radiative cooling is a method that achieves passive cooling through radiation without external energy input, leveraging the inherent properties of the material. Current radiative cooling methods reflect sunlight while simultaneously emitting thermal radiation into the cold outer space through the Atmospheric Transparent Window (ATSW, 8-13 μm), achieving the desired cooling effect without consuming any energy or emitting any greenhouse gases. This material has great potential for energy conservation, and if commercialized, it could significantly reduce energy consumption for cooling.

[0003] Current research on daytime passive radiative cooling materials often targets white or mirror-like surfaces in pursuit of high solar reflectivity. The glaring white color can be harmful to the human eye, while a monochromatic appearance may not satisfy aesthetic preferences. More importantly, the application of colored daytime radiative cooling materials in fabrics can improve the thermal comfort of outdoor workers, and existing research has primarily focused on the following aspects: Based on the color formation mechanism, these can be divided into two approaches: pigment strategies and structural color strategies. The pigment strategy involves applying colorants directly to the daytime passive radiative cooling (PDRC) material, offering the advantages of simple preparation, low cost, and scalable production. The structural color strategy is achieved by carefully designing microstructured surfaces with specific visible reflectivity, such as planar photonic structures, spiral periodic structures, opal, or inverse opal structures.

[0004] Unfortunately, the equipment requirements are strict, there is a lack of systematic control over processing accuracy, there are many printing defects and scalability is limited. At the same time, the structural color materials have strong iridescence, and it is currently impossible to prepare single-color structural colors. Moreover, to further develop the structural color effect, high-refractive-index modulation materials are required.

[0005] Chinese patent publication CN118932741A discloses a colored radiant cooling waterproof coating. The coating's components include a polymer, a solvent-based three-proofing finish, radiant particles, an organic solvent, and either a nano-inorganic dye or an oil-based nano-organic dye. Through the selection of the polymer, the amount of pigment added, the hierarchical pore structure, and the construction of the inorganic particles, this invention compensates for the absorption of a small amount of pigment in the solar wavelength range and enhances sunlight reflection.

[0006] Chinese patent publication CN118459818A discloses a colored radiative cooling coating based on a rare earth sulfide colorant. To achieve higher reflectivity, a thin film is formed using TiO2 powder, polydimethylsiloxane, a curing agent, and N,N-dimethylformamide as a substrate. The resulting coating exhibits high reflectivity in the near-infrared region, where solar energy is highly concentrated, enabling radiative cooling. This invention also allows for the design of different colors to meet varying market demands. The coating exhibits excellent self-cleaning properties and a simple, efficient preparation process, making it suitable for large-scale production. Summary of the Invention

[0007] The present invention provides an inorganic pigment-based colored radiation cooling coating fabric and a preparation method thereof, which overcomes the problems of monotonous color, complex preparation method, high cost and the like in the prior art.

[0008] The technical solutions of the present invention are as follows: An inorganic pigment-based colored radiation cooling coating fabric comprises a fiber fabric, and a daytime passive radiation coating and a modified inorganic pigment coating sequentially coated on the surface of the fiber fabric; The daytime passive radiation coating is an inorganic nanoparticle coating; the particle size distribution of the inorganic nanoparticles is nanometer-level, the solar reflectivity is above 90%, and the mid-infrared radiation rate is above 85%; The preparation method of the modified inorganic pigment comprises: The inorganic pigment is ball-milled and added to an organic solvent, and then an inorganic non-metallic material is added and mixed evenly, and the upper layer of the solution is taken after standing, and dried to obtain inorganic non-metallic microspheres with the inorganic pigment adsorbed on the surface; The inorganic non-metallic microspheres with inorganic pigments adsorbed on the surface are calcined to obtain modified inorganic pigments.

[0009] Modified inorganic pigments are composite particles of inorganic non-metals wrapped with inorganic pigments. The vibration of anionic groups and specific groups (such as water molecules, carbonate ions, etc.) that constitute the inner core layer of the composite particles presents a specific absorption frequency in the infrared spectrum, which can generate strong infrared radiation and help to increase the infrared emissivity of the fabric at the atmospheric window.

[0010] The inorganic non-metallic material is at least one of silicon dioxide, aluminum oxide, zirconium oxide, silicate glass and borate glass.

[0011] The particle size of the inorganic non-metallic material is 30~60μm.

[0012] The inorganic pigment is at least one of iron oxide yellow, iron oxide red and iron blue. The inorganic pigment has high reflectivity.

[0013] The mass ratio of the inorganic non-metallic material to the inorganic pigment is 1:3-6.

[0014] The inorganic nanoparticles are at least one of silicon dioxide, titanium dioxide, aluminum oxide, aluminum phosphate, and barium sulfate particles.

[0015] The particle size of the inorganic nanoparticles is 50-1000 nm.

[0016] The inorganic nanoparticle coating has high reflectivity to visible light-near infrared sunlight and high emissivity in the 8-13 μm atmospheric window.

[0017] In order to improve the bonding strength between inorganic nanoparticles and fabrics, preferably, the preparation method of the daytime passive radiation coating includes: The adhesive polydimethylsiloxane is dissolved in an organic solvent, and then inorganic nanoparticles are dispersed therein and stirred to obtain an inorganic nanoparticle dispersion; the inorganic nanoparticle dispersion is sprayed on the fabric and dried to obtain a daytime passive radiation coating.

[0018] The present invention utilizes polydimethylsiloxane to combine inorganic nanoparticles onto fabric, thereby improving the adhesion fastness of the inorganic nanoparticles.

[0019] The mass ratio of the binder to the organic solvent is 1:20-30.

[0020] The organic solvent is tetrahydrofuran.

[0021] The mass ratio of the inorganic nanoparticles to the polydimethylsiloxane is 1:0.1-0.3.

[0022] In the inorganic nanoparticle dispersion, the mass fraction of the inorganic nanoparticles is 5-40%.

[0023] More preferably, in the inorganic nanoparticle dispersion, the mass fraction of the inorganic nanoparticles is 20-30%.

[0024] When the appropriate amount of daytime passive radiation coating is applied, it scatters light, increasing the reflectivity of inorganic pigment-based colored radiation cooling coating fabrics. However, when the coating is too thick, the scattering centers become too dense, causing light to scatter multiple times within the coating. Some light will deviate from the reflection direction, while some will be scattered into the coating and absorbed, thus reducing the fabric's reflectivity. When the coating is too thin, some light will not be reflected but will be transmitted through the fabric, resulting in a relatively low reflectivity.

[0025] Preferably, the mass ratio of the daytime passive radiation coating to the fiber fabric per unit area is 1:0.5-1.5.

[0026] The fiber fabrics are cotton fabrics, polyester fabrics, spandex fabrics, nylon fabrics, acrylic fabrics, Tencel fabrics, hemp fiber fabrics and the like.

[0027] The preparation method of the modified inorganic pigment coating comprises: The modified inorganic pigment is dispersed in an organic solvent to obtain a modified inorganic pigment suspension, the modified inorganic pigment suspension is sprayed on the daytime passive radiation coating, and dried to obtain a modified inorganic pigment coating.

[0028] If the amount of modified inorganic pigment coating applied is too little, the inorganic non-metallic material's ability to reflect sunlight will be relatively weakened, and the fabric's reflectivity will also be relatively reduced. If the amount of coating applied is too much, the inorganic pigment's covering effect will block the reflective effect of the underlying inorganic nanoparticles, thereby reducing the fabric's reflective effect.

[0029] Preferably, the coating amount of the modified inorganic pigment coating is 5-15 mg / cm 2 .

[0030] Compared with the prior art, the present invention has the following beneficial effects: The colored daytime radiation cooling coating fabric provided by the present invention is designed by layering functional coatings and then assembled, so that ordinary fiber fabrics have excellent high reflection of visible and near-infrared sunlight and strong emission of infrared in the atmospheric window (8-13 μm), thereby realizing efficient radiation cooling under sunlight; at the same time, the outermost inorganic pigment coating gives the fiber fabric richer colors, eliminates the need for a highly reflective silver layer, has low cost, and has a wider range of applications.

[0031] The invention has low cost and simple operation, realizes radiation cooling on a color basis, and has great significance in the field of energy conservation and environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is the visible-near infrared reflection spectrum of the colored radiation cooling coating fabric in Example 2; Figure 2 The visible-near infrared reflection spectra of the inorganic pigment before and after modification in Example 2; Figure 3 This is the SEM image of the colored radiation cooling coating fabric in Example 2; Figure 4 This is a temperature comparison curve diagram of the colored radiation cooling coating fabric in Example 2 obtained through a simulation device. DETAILED DESCRIPTION

[0033] The present invention will be further described in detail below with reference to the accompanying drawings and examples. It should be noted that the following examples are intended to facilitate understanding of the present invention and do not have any limiting effect on the present invention.

[0034] Example 1 The preparation method of modified inorganic pigment is: (1) Add the inorganic pigment and alcohol solution into the ball mill, and after uniform ball milling, separate the pigment from the zirconium beads to obtain dispersed pigment; (2) Add the dispersed pigment to the organic solvent, mix well, then add the inorganic non-metallic material according to the corresponding proportion, use a cell crusher to ultrasonically disperse for 25 minutes, let it stand, take the upper layer solution, and dry it to obtain the modified inorganic pigment.

[0035] Example 2 An inorganic pigment-based colored radiation cooling coating fabric is prepared by the following steps: (1) According to the following weight ratio, 25 parts of silica (900 nm) and 3 parts of polydimethylsiloxane are added to 60 parts of tetrahydrofuran and heated at 40 °C for 2 h to obtain a silica suspension.

[0036] (2) Take 2 parts of silicate glass (50 μm), 10 parts of iron oxide yellow pigment and 20 parts of anhydrous ethanol as organic solvent, and prepare inorganic pigment-coated silicate glass composite particles according to the method of Example 1. The inorganic pigment-coated silicate glass composite particles are dispersed in the organic solvent to obtain an inorganic pigment composite particle suspension.

[0037] (3) Immersing the cotton fabric in the inorganic particle suspension in step (1) 2 to 3 times and drying it, then spraying the inorganic pigment composite particle suspension in step (2) onto the fabric 1 to 2 times and drying it to obtain a colored daytime radiation cooling coating fabric.

[0038] The coating amount of silica in the colored daytime radiation cooling coating fabric is 37.19 mg / cm 2 The coating amount of inorganic pigment composite particles is 10 mg / cm 2 .

[0039] Figure 1 This is the reflectance spectrum of the colored daytime radiation cooling coating fabric in Example 2 in the visible-near infrared band under an ultraviolet spectrophotometer. The colored coating fabric absorbs sunlight of specific wavelengths in the visible light band to present a colorful appearance, while still having a high reflectance in the near-infrared band to ensure a good radiation cooling effect. Figure 2 The visible-near-infrared reflectance spectra of the inorganic pigment before and after modification in Example 2 are shown. The modified inorganic pigment has a better visible-near-infrared reflectance. Figure 3 This is a microscopic image of the surface of the colored passive radiative cooling coated fabric in Example 2 under a desktop scanning electron microscope. It can be observed that the inorganic particles are fixed to the fabric by the polymer, and the inorganic pigments are attached to the surface of the particles. Figure 4This is a temperature comparison curve of the colored daytime radiant cooling coating fabric in Example 2 under a simulated light source. It can be seen from the figure that the colored passive radiant cooling fabric can achieve a temperature drop of 1 degree lower than the ambient temperature.

[0040] Example 3 An inorganic pigment-based colored radiation cooling coating fabric is prepared by the following steps: (1) According to the following weight ratio, add 25 parts of barium sulfate (900 nm) and 3 parts of polydimethylsiloxane to 60 parts of tetrahydrofuran and heat at 40 °C for 2 h to obtain a barium sulfate suspension.

[0041] (2) Immerse the cotton fabric in the inorganic particle suspension in step (1) 2 to 3 times and dry it. Then, spray the inorganic pigment composite particle suspension in step (2) of Example 2 onto the fabric 1 to 2 times and dry it to obtain a colored daytime radiation cooling coating fabric.

[0042] Example 4 An inorganic pigment-based colored radiation cooling coating fabric is prepared by the following steps: (1) According to the following weight ratio, 25 parts of titanium dioxide (100 nm) and 3 parts of polydimethylsiloxane are added to 60 parts of tetrahydrofuran and heated at 40 °C for 2 h to obtain a silica suspension.

[0043] (2) Immerse the cotton fabric in the inorganic particle suspension in step (1) 2 to 3 times and dry it. Then, spray the inorganic pigment composite particle suspension in step (2) of Example 2 onto the fabric 1 to 2 times and dry it to obtain a colored daytime radiation cooling coating fabric.

[0044] Example 5 An inorganic pigment-based colored radiation cooling coating fabric is prepared by the following steps: (1) According to the following weight ratio, add 25 parts of silicon dioxide and 3 parts of sodium carboxymethyl cellulose to 60 parts of tetrahydrofuran and heat at 40 °C for 2 h to obtain a silicon dioxide suspension.

[0045] (2) Immerse the cotton fabric in the inorganic particle suspension in step (1) 2 to 3 times and dry it. Then, spray the inorganic pigment composite particle suspension in step (2) of Example 2 onto the fabric 1 to 2 times and dry it to obtain a colored daytime radiation cooling coating fabric.

[0046] Example 6 An inorganic pigment-based colored radiation cooling coating fabric is prepared by the following steps: (1) According to the following weight ratio, add 25 parts of silicon dioxide and 3 parts of hydroxyethyl cellulose to 60 parts of tetrahydrofuran and heat at 40 °C for 2 h to obtain a silicon dioxide suspension.

[0047] (2) Immerse the cotton fabric in the inorganic particle suspension in step (1) 2 to 3 times and dry it. Then, spray the inorganic pigment composite particle suspension in step (2) of Example 2 onto the fabric 1 to 2 times and dry it to obtain a colored daytime radiation cooling coating fabric.

[0048] Example 7 An inorganic pigment-based colored radiation cooling coating fabric is prepared by the following steps: (1) According to the following weight ratio, 25 parts of silicon dioxide and 3 parts of polydimethylsiloxane are added to 60 parts of tetrahydrofuran and heated at 40 °C for 2 h to obtain a silicon dioxide suspension.

[0049] (2) Take 2 parts of aluminum oxide (100 nm), 10 parts of yellow iron oxide, and 20 parts of anhydrous ethanol as an organic solvent, and prepare inorganic pigment-coated aluminum oxide composite particles according to the method in Example 1. The inorganic pigment-coated aluminum oxide ions are dispersed in the organic solvent to obtain an inorganic pigment composite particle suspension.

[0050] (3) Immersing the cotton fabric in the inorganic particle suspension in step (1) 2 to 3 times and drying it, then spraying the inorganic pigment composite particle suspension in step (2) onto the fabric 1 to 2 times and drying it to obtain a colored daytime radiation cooling coating fabric.

[0051] Example 8 An inorganic pigment-based colored radiation cooling coating fabric is prepared by the following steps: (1) According to the following weight ratio, 25 parts of silicon dioxide and 3 parts of polydimethylsiloxane are added to 60 parts of tetrahydrofuran and heated at 40 °C for 2 h to obtain a silicon dioxide suspension.

[0052] (2) Immerse the polyester fabric in the inorganic particle suspension in step (1) 2 to 3 times and dry it. Then spray the inorganic pigment composite particle suspension in step (2) of Example 2 onto the fabric 1 to 2 times and dry it to obtain a colored daytime radiation cooling coating fabric.

[0053] Example 9 An inorganic pigment-based colored radiation cooling coating fabric is prepared by the following steps: (1) According to the following weight ratio, 25 parts of silicon dioxide and 3 parts of polydimethylsiloxane are added to 60 parts of tetrahydrofuran and heated at 40 °C for 2 h to obtain a silicon dioxide suspension.

[0054] (2) Immerse the spandex fabric in the inorganic particle suspension in step (1) 2 to 3 times and dry it. Then, spray the inorganic pigment composite particle suspension in step (2) of Example 2 onto the fabric 1 to 2 times and dry it to obtain a colored daytime radiation cooling coating fabric.

[0055] Example 10 An inorganic pigment-based colored radiation cooling coating fabric is prepared by the following steps: (1) According to the following weight ratio, 25 parts of silicon dioxide and 3 parts of polydimethylsiloxane are added to 60 parts of tetrahydrofuran and heated at 40 °C for 2 h to obtain a silicon dioxide suspension.

[0056] (2) Immerse the nylon fabric in the inorganic particle suspension in step (1) 2 to 3 times and dry it. Then, spray the inorganic pigment composite particle suspension in step (2) of Example 2 onto the fabric 1 to 2 times and dry it to obtain a colored daytime radiation cooling coating fabric.

[0057] Example 11 An inorganic pigment-based colored radiation cooling coating fabric is prepared by the following steps: (1) According to the following weight ratio, 25 parts of silicon dioxide and 3 parts of polydimethylsiloxane are added to 60 parts of tetrahydrofuran and heated at 40 °C for 2 h to obtain a silicon dioxide suspension.

[0058] (2) Immerse the acrylic fabric in the inorganic particle suspension in step (1) 2 to 3 times and dry it. Then, spray the inorganic pigment composite particle suspension in step (2) of Example 2 onto the fabric 1 to 2 times and dry it to obtain a colored daytime radiation cooling coating fabric.

[0059] Example 12 An inorganic pigment-based colored radiation cooling coating fabric is prepared by the following steps: (1) According to the following weight ratio, 25 parts of silicon dioxide and 3 parts of polydimethylsiloxane are added to 60 parts of tetrahydrofuran and heated at 40 °C for 2 h to obtain a silicon dioxide suspension.

[0060] (2) Immerse the Tencel fabric in the inorganic particle suspension in step (1) 2 to 3 times and dry it. Then, spray the inorganic pigment composite particle suspension in step (2) of Example 2 onto the fabric 1 to 2 times and dry it to obtain a colored daytime radiation cooling coating fabric.

[0061] Example 13 An inorganic pigment-based colored radiation cooling coating fabric is prepared by the following steps: (1) According to the following weight ratio, 25 parts of silicon dioxide and 3 parts of polydimethylsiloxane are added to 60 parts of tetrahydrofuran and heated at 40 °C for 2 h to obtain a silicon dioxide suspension.

[0062] (2) Immerse the hemp fiber fabric in the inorganic particle suspension in step (1) 2 to 3 times and dry it. Then, spray the inorganic pigment composite particle suspension in step (2) of Example 2 onto the fabric 1 to 2 times and dry it to obtain a colored daytime radiation cooling coating fabric.

[0063] The colored daytime radiation cooling coating fabrics prepared in Examples 3-13 have a cooling effect similar to that of Example 2.

[0064] The embodiments described above provide a detailed description of the technical solutions and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, supplements and equivalent substitutions made within the scope of the principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An inorganic pigment-based colored radiation cooling coating fabric, characterized in that: The invention comprises a fiber fabric and a daytime passive radiation coating and a modified inorganic pigment coating sequentially coated on the surface of the fiber fabric; The daytime passive radiation coating is an inorganic nanoparticle coating; the particle size distribution of the inorganic nanoparticles is nanometer-level, the solar reflectivity is above 90%, and the mid-infrared radiation rate is above 85%; The preparation method of the modified inorganic pigment comprises: The inorganic pigment is ball-milled and added to an organic solvent, and then an inorganic non-metallic material is added and mixed evenly, and the upper layer of the solution is taken after standing, and dried to obtain inorganic non-metallic microspheres with the inorganic pigment adsorbed on the surface; The inorganic non-metallic microspheres with inorganic pigments adsorbed on the surface are calcined to obtain modified inorganic pigments.

2. The inorganic pigment-based colored radiation cooling coating fabric according to claim 1, characterized in that: The inorganic non-metallic material is at least one of silicon dioxide, aluminum oxide, zirconium oxide, silicate glass and borate glass.

3. The inorganic pigment-based colored radiation cooling coating fabric according to claim 1, characterized in that: The inorganic pigment is at least one of iron oxide yellow, iron oxide red and iron blue.

4. The inorganic pigment-based colored radiation cooling coating fabric according to claim 1, characterized in that: The inorganic nanoparticles are at least one of silicon dioxide, titanium dioxide, aluminum oxide, aluminum phosphate, and barium sulfate particles.

5. The inorganic pigment-based colored radiation cooling coating fabric according to claim 1, characterized in that: The preparation method of the daytime passive radiation coating includes: The adhesive polydimethylsiloxane is dissolved in an organic solvent, and then inorganic nanoparticles are dispersed therein and stirred to obtain an inorganic nanoparticle dispersion; the inorganic nanoparticle dispersion is sprayed on the fabric and dried to obtain a daytime passive radiation coating.

6. The inorganic pigment-based colored radiation cooling coating fabric according to claim 5, characterized in that: The mass ratio of the binder to the organic solvent is 1:20-30; the mass ratio of the inorganic nanoparticles to the binder is 1:0.1-0.

3.

7. The inorganic pigment-based colored radiation cooling coating fabric according to claim 5, characterized in that: In the inorganic nanoparticle dispersion, the mass fraction of the inorganic nanoparticles is 5-40%.

8. The inorganic pigment-based colored radiation cooling coating fabric according to claim 1, characterized in that: The mass ratio of the daytime passive radiation coating to the fiber fabric per unit area is 1:0.5~1.

5.

9. The inorganic pigment-based colored radiation cooling coating fabric according to claim 1, characterized in that: The preparation method of the modified inorganic pigment coating comprises: The modified inorganic pigment is dispersed in an organic solvent to obtain a modified inorganic pigment suspension, the modified inorganic pigment suspension is sprayed on the daytime passive radiation coating, and dried to obtain a modified inorganic pigment coating.

10. The inorganic pigment-based colored radiation cooling coating fabric according to claim 1, characterized in that: The coating amount of the modified inorganic pigment coating is 5~15mg / cm 2 .

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