A method for preparing colored radiant refrigerated wood
By removing lignin from wood using NaClO2 acetate buffer solution and then permeating and polymerizing it with fluorescent dyes and methyl methacrylate monomers under vacuum, visible light full-spectrum colored radiation-cooled wood was prepared. This solved the preparation problem in the existing technology, achieved a low-cost, environmentally friendly and efficient colored radiation cooling effect, and expanded its application prospects in buildings.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- NORTHEAST FORESTRY UNIV
- Filing Date
- 2024-04-02
- Publication Date
- 2026-05-26
AI Technical Summary
Existing microstructured color radiation coolers are difficult to fabricate, have high production costs, and are not environmentally friendly, making them difficult to apply in practical scenarios.
Lignin in wood was removed using NaClO2 acetic acid buffer solution. Fluorescent dyes and methyl methacrylate monomers were then permeated and polymerized under vacuum to prepare visible full-spectrum colored radiation-cooled wood. PMMA molecules were used to enhance emissivity and uniformly distribute the dye.
This invention enables the simple preparation of colored radiant cooling wood, reduces production costs and environmental pollution, and provides excellent radiant cooling effect and color performance, making it suitable for radiant heat management in buildings.
Smart Images
Figure CN118181435B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a method for preparing wood that achieves full-spectrum visible light color radiation cooling. Background Technology
[0002] The energy crisis and climate change are major challenges facing all of humanity in the 21st century. With global warming, the accelerated consumption of energy is accompanied by a growing demand for cooling. Currently, cooling accounts for about 10% of global electricity consumption. Traditional cooling technologies not only consume large amounts of energy but also exacerbate the greenhouse effect and cause environmental problems. Passive cooling strategies, as environmentally friendly and carbon-reducing cooling technologies, are a key step in achieving energy reform and industrial upgrading.
[0003] Radiative cooling technology refers to the spontaneous cooling process of objects on the Earth's surface radiating heat into outer space through "atmospheric windows" (mainly 8-13 μm). Passive radiative coolers with high solar reflectance and mid-infrared emission are rapidly developing. However, radiative cooling materials below ambient temperature are often limited by aesthetic constraints of white or silver. Colored radiative coolers will further broaden the application potential of radiative cooling technology and enhance its application scenarios and value. The color display and radiative cooling performance of colored radiative coolers are mutually restrictive because the visible light band requires a specific reflectance spectrum to display the spectrum. Novel colored radiative cooling materials, such as photonic crystals and metamaterials, possess high solar spectral reflectance and high emissivity in the "atmospheric window" band, enabling colored passive radiative cooling. Patent CN114719464A, entitled "A Method for Preparing an Iridescent Colored Radiative Cooling Device," discloses an iridescent radiative cooler based on bio-inspired microcones. The cooling color cannot maintain uniformity with changing viewing angles; the color is not fixed and is strongly dependent on the wavelength and incident angle of the illumination light. Furthermore, it has been demonstrated that metallic dielectric metamaterials can exhibit excellent passive radiative cooling effects. Patent CN 113791468A, entitled "Colored Radiative Cooling Material and its Preparation Method," discloses a colored radiative cooler with controllable color and low visible light absorption. Although the color can be precisely adjusted by changing the thickness of the insulating layer, the achieved color is relatively light, and it requires twisting multiple layers of scattering elements to redirect the direction of incident light. Reducing the impact of visible light absorption is a key consideration for radiative coolers with high cooling performance. Patent CN114808433A, entitled "A Colored Cooling Film," discloses a colored cooling film combining photoluminescence and radiative cooling, converting absorbed visible light into emitted light to minimize the generation of solar heat. However, its photoluminescent material, perovskite quantum dots, suffers from complex preparation processes, lead toxicity, high cost, and low yield, making large-scale production difficult and limiting its practical application potential in buildings. Therefore, exploring the practical application of colored radiative cooling technology in different scenarios is expected to contribute to my country's carbon peaking and carbon neutrality efforts. Summary of the Invention
[0004] The purpose of this invention is to solve the problems of existing microstructure color radiation coolers, such as difficulty in preparation, high production cost, and lack of environmental friendliness, and to provide a method for preparing visible full-spectrum color radiation cooled wood.
[0005] The method for preparing visible light full-spectrum color radiation-cooled wood according to the present invention is implemented according to the following steps:
[0006] I. Preparation of Radiant Cooled Wood:
[0007] An acetic acid buffer solution with a concentration of 0.5wt% to 3wt% NaClO2 was prepared as the lignin removal solution. The dried wood was immersed in the lignin removal solution under vacuum for 5 to 24 hours. Then the wood was immersed in the lignin removal solution and reacted in a water bath at a temperature of 75 to 80°C for 12 to 24 hours. The lignin removal solution was changed several times during the water bath. The treated wood was then soaked in water and freeze-dried to obtain delignified wood.
[0008] II. Prepolymerization treatment:
[0009] The fluorescent dye was dispersed in an organic solvent, stirred evenly, and then mixed with methyl methacrylate (MMA) monomer. Azobisisobutyronitrile was added as an initiator, and prepolymerized at 70-90°C for 10-20 minutes to obtain a prepolymerized dye / MMA mixed solution.
[0010] III. Preparation of Colored Radiation-Cooled Wood:
[0011] Colored radiation-cooled wood is obtained by permeating delignified wood in a prepolymerized dye / MMA mixed solution under vacuum.
[0012] IV. Polymerization Processing:
[0013] Colored radiant refrigerated wood is placed into a polytetrafluoroethylene mold and heated at 70–90°C for polymerization reaction to obtain visible full-spectrum colored radiant refrigerated wood.
[0014] This invention provides a method for preparing visible full-spectrum colored radiatively cooled wood, achieving coloring of the wood without affecting the radiative cooling effect. This invention utilizes the stretching vibrations of C=O and COC bonds in PMMA molecules to enhance the emissivity of the colored radiatively cooled wood within the atmospheric window. Furthermore, the dye molecules are uniformly distributed within the PMMA, and the polymer provides spacing and steric hindrance, effectively preventing fluorescence quenching caused by resonant energy transfer of aggregated dyes.
[0015] Compared with existing technologies, the preparation method of visible light full-spectrum color radiation-cooled wood of the present invention has the following beneficial effects:
[0016] 1. The preparation process of the colored radiation-cooled wood of the present invention is simple.
[0017] 2. The main raw material used in this invention is wood, which is abundant, low-cost, renewable, sustainable, environmentally friendly, and easy to process.
[0018] 3. The radiation-cooled wood prepared by this invention is not only hard and durable, with excellent processing performance and low cost, but also generates less pollution during production and processing, and has good environmental protection properties, which can significantly reduce carbon emissions and energy consumption.
[0019] 4. The colored radiation-cooled wood surface prepared by this invention has excellent color effect and can achieve the full spectrum of visible light colors.
[0020] 5. The colored radiation-cooled wood prepared by this invention has a contact angle of about 137°, and has good hydrophobic and self-cleaning functions.
[0021] 6. Under the condition of heating at 70°C, the polymerization process of the permeation solution wood is completed in 2 hours. The emissivity of the three colors of colored radiation-cooled wood in the 8-13μm atmospheric window is 94.2%.
[0022] The delignified wood used in this invention is green and environmentally friendly. While maintaining excellent mechanical strength, it can also reasonably set the shape and size of the colored radiant cooler according to the needs of the scenario, and takes into account both flexibility and toughness. It is inexpensive and has excellent aging resistance, giving colored radiant cooling wood a broader application prospect in radiant heat management buildings. Attached Figure Description
[0023] Figure 1 Photographs of the radiation-cooled wood (left) and log (right) obtained in Example 1;
[0024] Figure 2 A photograph of the color-coded radiative-cooled wood obtained in Example 1;
[0025] Figure 3 The fluorescence image of the colored radiative-cooled wood obtained in Example 1 under an ultraviolet lamp;
[0026] Figure 4 This is a scanning electron microscope image of a tangential section of natural wood in Example 1;
[0027] Figure 5 This is a scanning electron microscope image of a tangential section of the radiation-cooled wood obtained in Example 1.
[0028] Figure 6 A scanning electron microscope image of a tangential section of the color-radiation-cooled wood obtained in Example 1;
[0029] Figure 7 This is a contact angle test diagram of the colored radiative cooling wood obtained in Example 1;
[0030] Figure 8 This is a characterization diagram of the solar reflectance of the radiatively cooled wood obtained in Example 1.
[0031] Figure 9 This is a characterization diagram of the solar reflectance of colored radiative-cooled wood obtained in Example 1.
[0032] Figure 10The infrared spectral emissivity characterization diagram of the colored radiation-cooled wood obtained in Example 1;
[0033] Figure 11 These are thermal images of logs, radiant-cooled wood, red radiant-cooled wood, yellow radiant-cooled wood, and blue radiant-cooled wood obtained in Example 1, taken outdoors and under a xenon lamp. Detailed Implementation
[0034] Specific Implementation Method 1: The preparation method of wood cooled by visible light full-spectrum color radiation in this implementation method is carried out according to the following steps:
[0035] I. Preparation of Radiant Cooled Wood:
[0036] An acetic acid buffer solution with a concentration of 0.5wt% to 3wt% NaClO2 was prepared as the lignin removal solution. The dried wood was immersed in the lignin removal solution under vacuum for 5 to 24 hours. Then the wood was immersed in the lignin removal solution and reacted in a water bath at a temperature of 75 to 80°C for 12 to 24 hours. The lignin removal solution was changed several times during the water bath. The treated wood was then soaked in water and freeze-dried to obtain delignified wood.
[0037] II. Prepolymerization treatment:
[0038] The fluorescent dye was dispersed in an organic solvent, stirred evenly, and then mixed with methyl methacrylate (MMA) monomer. Azobisisobutyronitrile was added as an initiator, and prepolymerized at 70-90°C for 10-20 minutes to obtain a prepolymerized dye / MMA mixed solution.
[0039] III. Preparation of Colored Radiation-Cooled Wood:
[0040] Colored radiation-cooled wood is obtained by permeating delignified wood in a prepolymerized dye / MMA mixed solution under vacuum.
[0041] IV. Polymerization Processing:
[0042] Colored radiant refrigerated wood is placed into a polytetrafluoroethylene mold and heated at 70–90°C for polymerization reaction to obtain visible full-spectrum colored radiant refrigerated wood.
[0043] The wood described in this embodiment is either cross-sectional wood or tangential wood, preferably tangential wood.
[0044] In this embodiment, the fluorescent dye can be Lumogen F Red 305, Lumogen F Yellow 083, Lumogen F Violet 570, or a cyanine dye.
[0045] In step three of this embodiment, delignified wood is permeated into a prepolymerized dye / MMA mixed solution under vacuum. Vacuum permeation is repeated multiple times to ensure uniform permeation of the colored radiant cooled wood.
[0046] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the wood mentioned in step one is balsa wood, poplar, larch, or fir.
[0047] Specific Implementation Method 3: This implementation method differs from Specific Implementation Method 1 or 2 in that, in step 1, the dried wood is immersed in a lignin removal solution under vacuum conditions for 10 to 20 hours.
[0048] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that the wood treated in Step One is then soaked in water for 24 to 48 hours.
[0049] Specific Implementation Method 5: This implementation method differs from Specific Implementation Methods 1 to 4 in that the freeze-drying temperature in step 1 is -18℃ to -80℃.
[0050] The optimized temperature for freeze-drying in this embodiment is -20℃ to -30℃.
[0051] Specific Implementation Method Six: This implementation method differs from one of Specific Implementation Methods One to Five in that the organic solvent mentioned in step two is N,N-dimethylformamide, dimethyl sulfoxide, dichloromethane, or cyclohexane.
[0052] Specific Implementation Method Seven: This implementation method differs from one of the specific implementation methods one to six in that in step two, the fluorescent dye is dispersed in an organic solvent, and the concentration of the fluorescent dye solution is 0.1 to 1 mg / mL.
[0053] Specific Implementation Method Eight: This implementation method differs from one of Specific Implementation Methods One to Seven in that the amount of azobisisobutyronitrile added in step two is 0.5wt% to 1.5wt% of the methyl methacrylate monomer.
[0054] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods One to Eight in that the permeation treatment time in step three is 4 to 6 hours.
[0055] Specific Implementation Method 10: This implementation method differs from Specific Implementation Methods 1 to 9 in that the heating polymerization reaction time in step 4 is 2 to 3 hours.
[0056] Example 1: The preparation method of visible light full-spectrum color radiation-cooled wood in this example is carried out according to the following steps:
[0057] I. Preparation of Radiant Cooled Wood:
[0058] An acetic acid buffer solution with a concentration of 1.5 wt% NaClO2 (pH = 4.6) was prepared as the lignin removal solution. The dried wood was immersed in the lignin removal solution for 12 hours under a pressure of 10 kPa, and then reacted in a water bath at 75°C for 20 hours until the wood turned completely white. The lignin removal solution was changed several times during the water bath. The treated wood was then soaked in water for 9 hours, with the water changed every three hours. After freeze-drying, delignified wood (radiation-cooled wood) was obtained.
[0059] II. Prepolymerization treatment:
[0060] Fluorescent dyes were dispersed in dichloromethane at a concentration of 0.1–1 mg / ml, with three concentration gradients. After stirring evenly, the mixture was mixed with methyl methacrylate (MMA) monomers. Azobisisobutyronitrile (AIBN) was added as an initiator at a concentration of 1 wt% of the MMA monomers. The mixture was prepolymerized at 70°C for 15 minutes to obtain a prepolymerized dye / MMA mixed solution.
[0061] III. Preparation of Colored Radiation-Cooled Wood:
[0062] Delignified wood was placed in a prepolymerized dye / MMA mixed solution under vacuum and vacuum permeation was performed three times to ensure uniform permeation of the colored radiative-cooled wood. The permeation treatment lasted for a total of 3 hours, resulting in colored radiative-cooled wood.
[0063] IV. Polymerization Processing:
[0064] Colored radiant refrigerated wood was placed into a polytetrafluoroethylene mold and heated at 70°C for 2 hours to produce visible full-spectrum colored radiant refrigerated wood.
[0065] The wood used in this embodiment is 3mm thick cross-sectional wood and tangential wood.
[0066] In this embodiment, polymethyl methacrylate (PMMA) was used to modify wood. Fluorescent dyes have better stability in PMMA than polymers such as PET, PEN, and PI. Furthermore, the effective stretching vibration of the chemical bonds in PMMA allows the dye and PMMA to be modified on the surface of delignified wood. In addition to absorbing visible light for the desired color, it has high solar reflectivity in other bands of the solar spectrum and high infrared emissivity, resulting in a reflectivity superior to other polymers.
[0067] In this embodiment, three fluorescent dyes are used in step two. The first fluorescent dye is Lumogen F Red305, which appears red under visible light. The second fluorescent dye is Lumogen F Yellow 083, which appears yellow under visible light. The third fluorescent dye is a mixture of Lumogen F Violet 570 and a cyanine dye in a volume ratio of 20:1, which appears blue under visible light. The volume ratio of the fluorescent dye to the methyl methacrylate (MMA) monomer is 1:1.
[0068] In this embodiment Figure 1 Balsa wood logs (left image) and radiant cooled timber (right image). Figure 2 It is made of three colored radiant cooling woods: red, yellow, and blue. Figure 3 The images show the fluorescence of red, yellow, and blue colored radiative cooling wood under ultraviolet light. The colored radiative cooling wood prepared in this embodiment has vibrant colors, and the three primary colors of the colored radiative cooling wood provide a basis for preparing colored radiative coolers with a full spectrum of sunlight.
[0069] In this embodiment Figure 4 SEM images of balsa wood logs along the tree's growth direction are shown for comparison. Figure 5 Radiation-cooled wood (delignified wood obtained in step one) and Figure 6 The surface of colored radiation-cooled wood is rich in nanopores that can scatter most of the sunlight while still maintaining highly oriented microchannels. The anisotropic structure contributes to the material's anisotropic optical and good thermal properties.
[0070] Depend on Figure 7 This demonstrates that colored radiant refrigerated wood has excellent self-cleaning ability, significantly improves hydrophobicity, and enhances structural stability compared to traditional radiant refrigerated wood.
[0071] Depend on Figure 8 The results show that when radiative-cooled wood along the tree growth direction is freeze-dried at around -20℃, the reflectance in the 250-1000nm spectral range is 93.5%, compared to 89% for radiative-cooled wood along the tree growth direction freeze-dried at -50℃ to -80℃. The reflectance of the cross-section of the radiative-cooled wood is 63.5%, demonstrating excellent radiative cooling effect.
[0072] Depend on Figure 9 This demonstrates that colored radiative cooling wood exhibits high reflectivity in other wavelength ranges of the solar reflectance spectrum, in addition to absorbing visible light of the desired color.
[0073] Depend on Figure 10This indicates that colored radiative cooling wood has a high emissivity in the mid-infrared band, with an average emissivity of 94.2%, proving that colored radiative cooling wood has excellent radiative cooling effect in the mid-infrared band.
[0074] Depend on Figure 11 These are thermal images of the logs, radiatively cooled wood, red radiatively cooled wood, yellow radiatively cooled wood, and blue radiatively cooled wood in Example 1, taken outdoors and under a xenon lamp. The temperature of the logs is higher than the ambient temperature, the temperature of the radiatively cooled wood is always lower than the ambient temperature, and the temperature of the colored radiatively cooled wood is always lower than the ambient temperature but slightly higher than the ambient temperature. This indicates that the colored radiatively cooled wood has excellent radiative cooling effect and also has the aesthetic effect of color. Colored radiatively cooled wood will further expand the application prospects of radiative coolers in space cooling, solar cells, buildings, and other fields.
Claims
1. A method for preparing colored radiant refrigerated wood, characterized in that... The preparation method is carried out according to the following steps: I. Preparation of Radiant Cooled Wood: An acetic acid buffer solution with a concentration of 0.5 wt% ~ 3 wt% NaClO2 was prepared as the lignin removal solution. The dried tangential wood was immersed in the lignin removal solution under vacuum for 5 to 24 hours. Then the wood was immersed in the lignin removal solution and reacted in a water bath at 75 to 80°C for 12 to 24 hours. The lignin removal solution was changed several times during the water bath. The treated wood was then soaked in water and freeze-dried to obtain delignified wood. II. Prepolymerization treatment: The fluorescent dye is dispersed in an organic solvent, stirred evenly, and then mixed with methyl methacrylate monomer. Azobisisobutyronitrile is added as an initiator, and prepolymerized at 70~90℃ for 10~20 minutes to obtain a prepolymerized dye / MMA mixed solution. III. Preparation of Colored Radiation-Cooled Wood: Colored radiation-cooled wood is obtained by permeating delignified wood in a prepolymerized dye / MMA mixed solution under vacuum. IV. Polymerization Processing: Colored radiation-cooled wood is placed into a polytetrafluoroethylene mold and heated at 70~90℃ to produce visible full-spectrum colored radiation-cooled wood. The fluorescent dyes mentioned therein are BASF dyes Lumogen F Red 305, Lumogen F Yellow 083, Lumogen F Violet 570, or cyanine dyes.
2. The method for preparing colored radiant refrigerated wood according to claim 1, characterized in that... The wood mentioned in step one is balsa wood, poplar, larch, or cedar.
3. The method for preparing colored radiant refrigerated wood according to claim 1, characterized in that... In step one, the dried wood is immersed in a lignin removal solution under vacuum for 10-20 hours.
4. The method for preparing colored radiant refrigerated wood according to claim 1, characterized in that... The wood treated in step one is then soaked in water for 24-48 hours.
5. The method for preparing colored radiant refrigerated wood according to claim 1, characterized in that... The freeze-drying temperature in step one is -18℃ to -80℃.
6. The method for preparing colored radiant refrigerated wood according to claim 1, characterized in that... The organic solvent mentioned in step two is N,N-dimethylformamide, dimethyl sulfoxide, dichloromethane, or cyclohexane.
7. The method for preparing colored radiant refrigerated wood according to claim 1, characterized in that... In step two, the fluorescent dye is dispersed in an organic solvent, and the concentration of the fluorescent dye solution is 0.1~1 mg / mL.
8. The method for preparing colored radiant refrigerated wood according to claim 1, characterized in that... In step two, the amount of azobisisobutyronitrile added is 0.5 wt% to 1.5 wt% of the methyl methacrylate monomer.
9. The method for preparing colored radiant refrigerated wood according to claim 1, characterized in that... The permeation treatment time in step three is 4 to 6 hours.
10. The method for preparing colored radiant refrigerated wood according to claim 1, characterized in that... The heating polymerization reaction in step four takes 2 to 3 hours.