KR20240002274A - Thermosensitive radiative cooling material - Google Patents

Abstract

The present invention applies thermochromic particles to a radiative cooling material to reduce the internal temperature by increasing the radiative cooling effect when the external temperature is high, and maintains the internal temperature by reducing the radiative cooling effect when the external temperature is low, thereby maintaining the external wall of a structure such as an actual building. This relates to a temperature-sensitive radiative cooling material that can efficiently reduce the energy required for cooling and warming when applied to the back.

Description

Thermosensitive radiative cooling material

The present invention relates to a temperature-sensitive radiative cooling material. More specifically, the present invention applies thermochromic particles to a radiative cooling material to lower the internal temperature by increasing the radiative cooling effect when the external temperature is high, and maintains the internal temperature by reducing the radiative cooling effect when the external temperature is low, so that the actual building and This relates to a temperature-sensitive radiative cooling material that can efficiently reduce the energy required for cooling and warming when applied to the exterior walls of the same structure.

As competition between countries to stabilize energy supply heats up, efficient energy management is urgently needed as a means of stabilizing energy supply and demand. Korea's energy intensity (the amount of energy required to produce $1,000 of GDP, TOE/$1,000) is 0.339, which is the highest among Organization for Economic Co-operation and Development (OECD) countries. This means that a lot of energy is needed to create added value equivalent to $1,000 of GDP. This can be interpreted to mean that energy is being used. In addition, Korea's primary energy consumption is 239.5 million TOE, ranking 10th in the world, and its dependence on oil is also high. The reason for Korea's low energy efficiency is because incentives for energy conservation are low.

Accordingly, the Ministry of Construction and Transportation has prepared an 'Innovative Plan for Building Energy Savings' to maximize energy savings in buildings, and supplementation is requested when materials with a high energy consumption efficiency rating are used. Interest in and policies for efficient energy use are expected to gradually increase, and recently, various energy-saving technologies for buildings, such as smart films, have been developed. In fact, since building energy consumption in the home industry sector accounts for more than 50% of total energy consumption, energy efficiency can be strengthened by improving the performance of windows and roofs of existing buildings, but there is also a need to reduce heat loss generated from exterior walls and roofs. The technology is still insignificant.

As a solution to this problem, technology that utilizes the radiative cooling phenomenon to provide cooling without power supply has recently been receiving a lot of attention. Radiation refers to the phenomenon of transferring energy through light. All objects with a temperature emit radiant energy, and the Earth emits most of its radiant energy into space in the form of infrared rays through the atmospheric window (8 to 13 μm wavelength range). In other words, the Earth receives energy from the sun, reflects some of it, absorbs the rest, and then re-emits it. Radiative cooling technology uses this principle of radiation.

In order to maximize radiation cooling efficiency, the optical coating material effectively reflects visible and near-infrared (vis-NIR) light to minimize heating by sunlight, and has a high emissivity in the far-infrared (long wavelength infrared, LWIR) region. It is important to design to maximize heat radiation from the surface to the atmosphere. This method reduces the amount of energy required to cool buildings that are inevitably exposed to sunlight during the day and summer.

The previously reported radiative cooling technology is always designed to have a lower temperature than the outside temperature, so it is useful in the summer when the outside temperature is high, during daytime during the change of seasons, etc., but it has the opposite effect in the winter, etc. when the outside temperature is low.

Accordingly, Republic of Korea Patent Publication No. 10-2020-0115351 discloses a temperature-sensitive smart radiation cooling technology, and more specifically, a black body radiation layer; And it is formed on the black body radiation layer and contains nanoparticles and a host material whose refractive index changes by generating a phase change in response to external temperature, thereby controlling the scattering of electromagnetic waves in the mid-IR region as well as sunlight. Thus, a temperature-sensitive radiation cooling technology that can simultaneously achieve cooling and warming is disclosed. However, in the above technology, it is difficult to control the size of the refractive index between the phase change material contained in each nanoparticle and the host material, and the rate at which the phase change material of the nanoparticle changes state depending on the depth or location of inclusion in the radiative cooling material or There is a problem that the heat blocking effect may be reduced because the time is not constant.

Accordingly, the inventors of the present invention applied thermochromic particles to a radiative cooling material to lower the internal temperature by increasing the radiative cooling effect when the external temperature is high, and maintain the internal temperature by reducing the radiative cooling effect when the external temperature is low, thereby maintaining the internal temperature of the actual building. We have developed a temperature-sensitive radiative cooling material that can efficiently reduce the energy required for cooling and warming when applied to the exterior walls of the same structure.

The present invention applies thermochromic particles to a radiative cooling material to reduce the internal temperature by increasing the radiative cooling effect when the external temperature is high, and maintains the internal temperature by reducing the radiative cooling effect when the external temperature is low, thereby maintaining the external wall of a structure such as an actual building. The goal is to provide a temperature-sensitive radiative cooling material that can efficiently reduce the energy required for cooling and warming when applied to the back.

In order to solve the above problem, the present invention includes a matrix polymer containing thermochromic particles and hollow inorganic particles that reversibly change color according to changes in ambient temperature, and the thermochromic particles and the hollow inorganic particles in the matrix polymer are each Temperature-sensitive, micro-sized, with a reflectivity of 0.9 or more in the near-infrared (NIR) wavelength range of 0.8 to 1.5 ㎛, and an emissivity of 0.8 or more in the far-infrared (LWIR) wavelength range of 8 to 13 ㎛. Provides type radiative cooling materials.

Here, the temperature-sensitive radiation cooling material has a reflectivity of 0.2 or less in the visible light range of 0.3 to 0.7 ㎛ when the ambient temperature is less than 30 ℃, and has a reflectivity of 0.3 to 0.7 ㎛ in the visible ray range of 0.3 to 0.7 ㎛ when the ambient temperature is 30 ℃ or higher. The reflectivity may be 0.7 or more.

In this case, the thermochromic particles include a core portion that performs a thermochromic function; And it may be in the form of a microsphere including a polymer shell portion surrounding the core portion.

In addition, the core portion of the thermochromic particles includes a coloring agent, an initiator, and a discoloration regulator, and the coloring agent and the initiator are discolored to white through a mutual neutralization reaction, and the discoloration regulator is a color change between the coloring agent and the initiator above the melting point. Discoloration can be prevented by controlling the neutralization reaction.

Additionally, the polymer shell portion may include melamine-based resin or methyl methacrylate resin (poly(methyl methacrylate); PMMA).

Furthermore, the thermochromic particles may have a size ranging from 1.0 to 5.0 ㎛.

Here, the thermochromic particles in the matrix polymer may be included in the range of 1 phr (parts per hundred resin) to 6 phr.

Additionally, the matrix polymer may include polydimethylsiloxane (PDMS).

In addition, the hollow inorganic particles may include a hollow structure containing at least one of titanium dioxide (TiO ₂ ), silica (SiO ₂ ), and yttrium oxide (Y ₂ O ₃ ).

In this case, the hollow inorganic particles in the matrix polymer may be included in the range of 30% to 70% by volume.

Furthermore, the present invention provides a temperature-sensitive radiative cooling film manufactured from the temperature-sensitive radiative cooling material.

In addition, the present invention provides a method for manufacturing the temperature-sensitive radiation cooling film, comprising the steps of mixing the matrix polymer, the hollow inorganic particles, the thermochromic particles, and a curing agent to prepare a coating solution; Applying the prepared coating solution to an object to be treated or an upper base layer using a wet coating process; and forming a film through a curing process. A method for manufacturing a temperature-sensitive radiation cooling film is provided.

Here, the step of forming the film involves wet coating processes such as bar coating, doctor-blade coating, slot-die coating, and roll-to-roll coating. It can be formed in the form of a film by curing the coating solution applied on the object to be treated or on the base layer.

According to the temperature-sensitive radiation cooling material according to the present invention, when the radiation cooling material is heated above a certain temperature by applying thermochromic particles, the visible light reflectance increases due to the discoloration of the thermochromic particles, so that the external temperature is high. When applied to structures such as actual buildings, it lowers the internal temperature by increasing the radiation cooling effect and maintains the internal temperature by reducing the radiation cooling effect when the outside temperature is low. This is an excellent effect that can efficiently reduce the energy required for cooling or warming when applied to structures such as actual buildings. represents.

Figure 1 schematically shows the configuration of a temperature-sensitive radiative cooling material according to the present invention.
Figure 2 shows an enlarged cross-sectional view of thermochromic particles of the temperature-sensitive radiative cooling material according to the present invention.
Figure 3 is a graph measuring solar irradiance and temperature over time to compare the cooling effect of the temperature-sensitive radiative cooling material according to the present invention.
Figure 4 is a thermal image for comparing the cooling effect of the temperature-sensitive radiative cooling material according to the present invention.
Figure 5 is a photograph showing the cross-sectional SEM and EDS mapping analysis results of Example 1.
Figure 6 is a graph showing the optical properties of the temperature-sensitive radiation cooling film of the present invention according to the ambient temperature in Example 1.
Figure 7 is a graph of temperature change of the radiative cooling film of the present invention through external experiments in Example 1 and Comparative Example 1.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. However, the present invention is not limited to the embodiments described herein and may be embodied in other forms. Rather, the embodiments introduced herein are provided so that the disclosure will be thorough and complete, and so that the spirit of the invention can be sufficiently conveyed to those skilled in the art. Like reference numerals refer to like elements throughout the specification.

Figure 1 schematically shows the configuration of a temperature-sensitive radiative cooling material according to the present invention.

As shown in Figure 1, the temperature-sensitive radiation cooling material according to the present invention may be composed of a matrix polymer containing micro-sized thermochromic particles and hollow inorganic particles. Here, the thermochromic particles and the hollow inorganic particles in the matrix polymer may each have a micro size.

The temperature-sensitive radiation cooling material according to the present invention uses a matrix polymer mixed with micro-sized hollow inorganic particles and thermochromic particles to emit far-infrared rays (LWIR) in the atmospheric window region, that is, in the range of about 8 to 13 ㎛. ) It will have a high emissivity of 0.8 or more in the wavelength range, and will be configured to have a high reflectivity of 0.9 or more in the near-infrared (NIR) wavelength range of 0.8 to 1.5 ㎛ due to the light scattering effect of the hollow inorganic particles. You can.

For reference, the reflectivity and radiance of the temperature-sensitive radiative cooling material can be calculated according to Kirchhoff's radiation law defined by Equation 1 below.

[Equation 1]

ε=1-R-T

In Equation 1 above,

ε is radiance (absorbance), R is reflectance, and T is transmittance.

The matrix polymer of the temperature-sensitive radiation cooling material is a polymer resin with a high absorption rate in the far-infrared wavelength range of about 8 to 13 μm, such as polylactic acid (PLA), polyurethane (PU), and polyethylene (PE). ), polymers such as polypropylene (PP), polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), and polydimethylsiloxane (PDMS), preferably polydimethylsiloxane (PDMS). can do.

The matrix polymer contains micro-sized hollow inorganic particles therein. The hollow inorganic particles may include a hollow structure containing at least one of titanium dioxide (TiO ₂ ), silica (SiO ₂ ), and yttrium oxide (Y ₂ O ₃ ). The hollow inorganic particles can be adjusted to have a high reflectivity of 0.9 or more in the near-infrared (NIR) wavelength range of 0.8 to 1.5 ㎛ by generating a scattering effect on sunlight in the near-infrared region.

Furthermore, the matrix polymer includes hollow inorganic particles therein, so that a pore structure can be formed therein, which has the effect of achieving weight reduction of the radiative cooling material.

The content of the hollow inorganic particles may be in the range of 30 to 70% by volume based on the total volume of the matrix polymer. If the content of the hollow inorganic particles is less than 30% by weight, the solar light reflectance by the inorganic particles decreases and the radiative cooling efficiency decreases, whereas if the hollow inorganic particles exceed 70% by volume, the content of the matrix polymer decreases and the far-infrared emissivity decreases. This may decrease, and pores may be excessively formed inside the matrix polymer, resulting in a decrease in mechanical strength or thermal properties.

Furthermore, the temperature-sensitive radiation cooling material according to the present invention can efficiently reflect sunlight in the visible light range by incorporating thermochromic particles into the matrix polymer. Specifically, the temperature-sensitive radiation cooling material has a reflectivity of 0.2 or less in the visible light range of 0.3 to 0.7 ㎛ when the ambient temperature is less than 30 ℃, and a reflectivity of 0.3 to 0.7 ㎛ in the visible light range when the ambient temperature is 30 ℃ or more. The reflectivity can be adjusted to be 0.7 or more.

Here, 'thermal discoloration' refers to a change in at least one of color, saturation, and brightness depending on the surrounding temperature, and may include the concept of color changing to colorless, that is, discoloration and erasure.

The thermochromic particles may have a size ranging from 1.0 to 5.0 ㎛. The size of the thermochromic particles refers to the diameter of a sphere converted to have the same volume as the thermochromic particles.

The content of the thermochromic particles may be in the range of 1 phr (parts per hundred resin) to 6 phr based on the total weight of the matrix polymer. Here, when the content of the thermochromic particles is less than 1 phr, the discoloration effect of the thermochromic particles depending on the ambient temperature may be minimal, whereas when the content of the thermochromic particles is more than 6 phr, the tensile strength and elongation of the base resin Mechanical properties and processability may be reduced.

Hereinafter, the thermochromic particles of the temperature-sensitive radiative cooling material according to the present invention will be described with reference to FIG. 2.

Figure 2 shows an enlarged cross-sectional view of thermochromic particles included in the matrix polymer constituting the temperature-sensitive radiative cooling material according to the present invention.

As shown in Figure 2, the thermochromic particles include a core portion 10 that performs a thermochromic function; and a polymer shell portion 20 surrounding the core portion. It may be configured in the form of a microsphere including a. Additionally, an interface portion 30 may be further provided between the core portion 10 and the polymer shell portion 20.

Here, the core portion 10 of the thermochromic particle contains a thermochromic composition containing a coloring agent, an initiator (developer), and a color fading control agent, and the coloring agent and the initiator are respectively an electron donating compound and an electron accepting compound. Through oxidation/reduction reactions (neutralization reactions), it becomes a complete dye and can be discolored into the original color of the coloring agent, for example, black with a low visible light reflectance, or a color extremely similar to this.

The coloring agent and the initiator are not particularly limited as long as they are generally known in the art. For example, the coloring agent may include fluorane-based leuco dye, fluorene-based leuco dye, diphenylmethane phthalide-based leuco dye, and imdolyl phthalide. It may include leuco dyes such as leuco dyes based on spiropyran, leuco dyes based on spiropyran, leuco dyes based on rhodamine lactam, and leuco dyes based on azaphthalide, and the initiator may be triazole-based, phenol-based, bisphenol-based, or aromatic. It may include carboxylic acid-based, aliphatic carboxylic acid-based, thiourea-based, phosphoric acid-based, or their esters, ethers, metal salts, etc.

The discoloration regulator serves to block discoloration by controlling the neutralization reaction between the color developer and the initiator above the melting point (T _m ). Here, the melting point (T _m ) of the discoloration control agent can be adjusted to about 30°C. In this case, the discoloration control agent exists in a solid state below the melting point adjusted to about 30°C, but can change into a liquid above the melting point. .

Therefore, when the thermochromic particles are heated to about 30° C. or higher depending on the ambient temperature, the neutralization reaction between the color developer and the initiator is controlled by melting of the discoloration regulator, thereby blocking the discoloration of the thermochromic particles (discoloration ( It changes color to white due to the phenomenon of discoloration or discoloration of the coloring agent. On the other hand, when the thermochromic particles are cooled to less than 30°C in response to the ambient temperature, the discoloration control agent solidifies back to its original state and a neutralization reaction between the color developer and the initiator is initiated, causing the thermochromic particles to turn black again. The thermochromic particles may change color reversibly depending on the surrounding temperature.

As described above, when the type and corresponding melting point (T _m ), content, etc. of the discoloration regulator in the thermochromic particles are adjusted and the color of the coloring agent is appropriately applied, the temperature-sensitive radiative cooling material is Due to the discoloration phenomenon of the discolored particles, if the ambient temperature is less than 30℃, the reflectance is 0.2 or less in the visible light range of 0.3 to 0.7 ㎛, and if the ambient temperature is 30℃ or higher, the reflectivity is 0.7 in the visible light range of 0.3 to 0.7 ㎛. It can be adjusted above.

The discoloration control agent is, for example, fatty acid-based alcohol such as cetyl alcohol, stearyl alcohol, Myristyl alcohol, Behenyl alcohol, and Oleyl alcohol. may be included alone or in combination.

The polymer shell portion 20 is made of a hydrophobic material so that the thermochromic particles are uniformly dispersed within the hydrophobic matrix polymer without agglomerating with each other, and the thermochromic composition contained in the core portion 10 resists external pressure. The core portion 10 is wrapped and protected to prevent its properties from being deteriorated or deteriorated due to heat or heat. In this way, the thermochromic particles can ensure the stability and durability of the thermochromic particles by providing a polymer shell portion 20 surrounding the core portion 10, and at the same time, the thermochromic particles are uniformly distributed within the matrix resin. By being dispersed, effects such as cooling or warming of the radiative cooling material can be implemented uniformly and consistently.

Here, the hydrophobic material constituting the polymer shell portion 20 may be composed of various polymer resins generally used in the field of polymer micro-sphere (micro-capsule), preferably a melamine-based polymer resin, For example, it includes melamine-formaldehyde, melamine-urea copolymer resin, melamine-phenol copolymer resin, butylated melamine resin, melamine-urea-formaldehyde copolymer resin, etc., or methyl methacrylate resin (Poly(methyl) methacrylate); PMMA).

In addition, the thermochromic particle may further include an interface portion 30 between the core portion 10 and the polymer shell portion 20 for coupling the core portion 10 and the polymer shell portion 20 to each other. there is.

The interface portion 30 may be composed of a surfactant, and the surfactant is arranged on the surface of the core portion 10 to form a micelle structure and is a component constituting the polymer shell portion 20. By pulling the core portion 10 and the polymer shell portion 20 by electrostatic attraction to weaken the surface tension of the interface between the core portion 10 and the polymer shell portion 20, the core portion 10 and the polymer shell portion 20 can be stably coupled. .

Here, the surfactant may include, for example, ethylene maleic anhydride copolymer, polyvinyl alcohol, styrene-maleic anhydride copolymer, methylellulose, carboxymethylcellulose polyoxyethylene stiaryl ether, etc.

Figure 3 is a graph measuring solar irradiance and temperature over time to compare the cooling effect of the temperature-sensitive radiative cooling material according to the present invention, and Figure 4 is a graph showing the cooling of the temperature-sensitive radiative cooling material according to the present invention. This is a thermal image to compare the effect.

In order to compare the cooling effect of the temperature-sensitive radiative cooling material according to the present invention, a coating material to which the temperature-sensitive radiative cooling material was applied, a generally commercially available commercial white paint, a commercial black paint, and a transparent substrate to which only thermochromic particles were added were used. used. Here, the transparent substrate did not use a matrix polymer containing micro-hollow inorganic particles.

The coating material, commercial paint, and transparent substrate using the temperature-sensitive radiative cooling material according to the present invention are each applied on the top of the base layer and then exposed to solar irridation (W/m ² ) from the outside for about 5 days. The temperature was measured in this state.

As shown in Figure 3, the coating material using the temperature-sensitive radiation cooling material according to the present invention has a high solar reflectance by using a polymer containing micro-hollow inorganic particles, and has a high solar reflectance and far-infrared ray (LWIR) in the range of 8 to 13 ㎛. Because the thermal emissivity in the wavelength range is high and the radiative cooling effect is excellent, it was able to maintain a lower temperature than other commercial paints and transparent substrates that do not contain micro particles even during times when solar irradiance is relatively high.

In addition, as a result of measuring the temperature at 2 PM, when the solar irradiance is relatively high during the day, thermal images of the coating material, commercial white paint, commercial black paint, and transparent substrate applied with the temperature-sensitive radiative cooling material according to the present invention were obtained. The photograph was taken and shown in Figure 4. In the thermal image, the closer it is to red, the higher the temperature is, and the closer it is to blue, the lower the temperature. As shown in Figure 4, it was confirmed that the temperature-sensitive radiative cooling material according to the present invention was particularly excellent in cooling effect by solar light scattering, thereby maintaining a low temperature.

Furthermore, the present invention can manufacture the temperature-sensitive radiation cooling material in the form of a film. The temperature-sensitive radiation cooling film according to the present invention is prepared by mixing a matrix polymer, micro-sized hollow inorganic particles, micro-sized thermochromic particles, and a curing agent to prepare a coating solution, and using a wet coating process. It may include applying the coated coating solution to the object to be treated or on the top of the base layer and forming a film through a curing process.

The base layer may be made of, for example, glass or a polymer material, such as polyethylene terephthalate (PET) or polyimide (PI).

The step of forming the film is performed using a wet coating process such as bar coating, doctor-blade coating, slot-die coating, and roll-to-roll coating. The final film form can be produced by curing the coating solution applied on the object to be treated or on the base layer.

As such, the manufacturing method of the temperature-sensitive radiation cooling film according to the present invention can be easily manufactured by enabling a wet coating process, and does not involve high-temperature heat treatment, so the process cost is low and the process is relatively simple, so it can be compared to existing photonic crystals. It has the advantage of being more efficient than manufacturing process conditions using structure-based patterning and deposition and being easy to apply to structures such as actual buildings that require a large area.

In addition, the temperature-sensitive radiation-cooling film finally manufactured by the above-described temperature-sensitive radiation-cooling film manufacturing method maintains a high emissivity in the far-infrared wavelength range of 8 to 13 ㎛ when applied to structures such as actual buildings, and provides excellent protection against sunlight. Thermochromic particles that have excellent reflectivity, especially in the near-infrared wavelength range of 0.8 to 1.5 ㎛, have excellent radiative cooling efficiency, and further control visible light reflectivity in the visible ray range of 0.3 to 0.7 ㎛ depending on the surrounding temperature. By including it, cooling or warming functions can be selectively performed in response to the surrounding temperature, which has the excellent effect of efficiently saving energy.

Hereinafter, the present invention will be described in more detail through examples. These examples are only for illustrating the present invention in more detail, and the scope of the present invention is not limited by these examples.

<Example>

1. Manufacturing example

1) Example 1: Temperature-sensitive radiative cooling film containing thermochromic particles

The silicone elastomer base material and curing agent (Sylgard 184, Dow Corning) were mixed at a weight ratio of 10:1, and 40% by volume of hollow silica particles and 6 phr thermochromic particles were stirred at room temperature. After sufficiently degassing the mixed coating solution, it was applied to the substrate to the desired thickness and cured in an oven at 110°C for 40 minutes.

2) Comparative Example 1: Radiant cooling film without thermochromic particles

The silicone elastomer base material and curing agent (Sylgard 184, Dow Corning) were mixed at a weight ratio of 10:1, 40% by volume of hollow silica particles were added, and the mixture was stirred at room temperature. After sufficiently degassing the mixed coating solution, it was applied to the substrate to the desired thickness and cured in an oven at 110°C for 40 minutes.

2. Physical property evaluation

1) Evaluation of optical properties

For the film of Example 1, the reflectivity for the corresponding wavelength range was measured using a UV-Vis-NIR spectrometer equipped with an integrating sphere accessory according to the ambient temperature, and a graph thereof is shown in FIG. 6.

As shown in Figure 6, the temperature-sensitive radiation cooling film of Example 1 containing thermochromic particles has a reflectivity of 0.2 or less at a wavelength in the range of 0.3 to 0.7 μm at an ambient temperature of less than 30°C, and a reflectivity of 0.2 or less at an ambient temperature of 30°C or more. It can be seen that the reflectivity is more than 0.7 at a wavelength ranging from 0.3 to 0.7 μm.

Through this, the temperature-sensitive radiative cooling material of Example 1 containing micro-sized thermochromic particles and hollow inorganic particles can change reflectivity depending on the surrounding environment at a temperature of 30°C, and does not contain thermochromic particles. The radiative cooling material of Comparative Example 1 shows that it has a constant reflectivity regardless of the surrounding temperature.

2) External experimental evaluation of temperature-sensitive radiative cooling film

The external tests shown in FIG. 7 were performed on the films of Example 1 and Comparative Example 1 at an ambient temperature of less than 30°C and an ambient temperature of more than 30°C, respectively. Specifically, the external radiation cooling test device used insulating polystyrene foam to prevent unnecessary heat transfer from the surroundings, and a silver reflective film was attached to the surface to prevent heating by sunlight. Each of the radiation cooling films of Example 1 and Comparative Example 1 was placed on the prepared Styrofoam, and the surface temperature change of the film was measured using a K-type thermocouple. A white leaf table was installed to measure wind speed, temperature, and solar radiation in real time using anemometers, thermometers, and solar irradiance meters. K-type thermocouples were additionally placed around the radiative cooling film to measure the temperature around the film.

The ambient temperature and radiation cooling efficiency of the film in the measured external environment are as shown in Figure 7. In an environment where the ambient temperature is less than 30℃, the temperature-sensitive radiative cooling film absorbs solar energy and raises the temperature by up to 7℃ compared to the surrounding temperature, making it possible to maintain the internal temperature of buildings, etc. without unnecessary radiative cooling in winter, and when the ambient temperature is 30℃ or higher. In the environment, the temperature-sensitive radiation cooling film of the present invention can be expected to have an excellent energy saving effect in buildings such as summer by lowering the temperature by up to 3°C or more.

Although this specification has been described with reference to preferred embodiments of the present invention, those skilled in the art may make various modifications and changes to the present invention without departing from the spirit and scope of the present invention as set forth in the claims described below. It will be possible to implement it. Therefore, if the modified implementation basically includes the elements of the claims of the present invention, it should be considered to be included in the technical scope of the present invention.

Claims (13)

It contains a matrix polymer containing thermochromic particles and hollow inorganic particles that reversibly change color in response to changes in ambient temperature,
The thermochromic particles and the hollow inorganic particles in the matrix polymer each have a micro-sized size,
Temperature-sensitive radiative cooling, characterized by a reflectivity of 0.9 or more in the near-infrared (NIR) wavelength range of 0.8 to 1.5 ㎛ and an radiance of 0.8 or more in the far-infrared (LWIR) wavelength range of 8 to 13 ㎛. Material. According to paragraph 1,
If the ambient temperature is less than 30℃, the reflectance is 0.2 or less in the visible light range of 0.3 to 0.7 ㎛, and if the ambient temperature is 30℃ or higher, the reflectance is 0.7 or more in the visible light range of 0.3 to 0.7 ㎛. type radiant cooling material. According to claim 1 or 2,
The thermochromic particles include a core portion that performs a thermochromic function; And a polymer shell portion surrounding the core portion. A temperature-sensitive radiation cooling material, characterized in that it is in the form of a microsphere including a. According to paragraph 3,
The core portion of the thermochromic particles includes a coloring agent, an initiator, and a discoloration regulator,
The coloring agent and the initiator are discolored to black through a mutual neutralization reaction, and the discoloration regulator blocks the discoloration phenomenon by controlling the neutralization reaction between the coloring agent and the initiator above the melting point. Cooling material. According to paragraph 3,
A temperature-sensitive radiative cooling material, wherein the polymer shell portion includes a melamine-based resin or a methyl methacrylate resin (poly(methyl methacrylate); PMMA). According to claim 1 or 2,
The thermochromic particles are a temperature-sensitive radiative cooling material, characterized in that the size ranges from 1.0 to 5.0 ㎛. According to claim 1 or 2,
A temperature-sensitive radiative cooling material, characterized in that the thermochromic particles in the matrix polymer are contained in the range of 1 phr (parts per hundred resin) to 6 phr. According to claim 1 or 2,
A temperature-sensitive radiative cooling material, wherein the matrix polymer includes polydimethylsiloxane (PDMS). According to claim 1 or 2,
The hollow inorganic particles are a temperature-sensitive radiative cooling material, characterized in that they include a hollow structure containing at least one of titanium dioxide (TiO ₂ ), silica (SiO ₂ ), and yttrium oxide (Y ₂ O ₃ ). According to claim 1 or 2,
A temperature-sensitive radiative cooling material, characterized in that the hollow inorganic particles in the matrix polymer are contained in the range of 30% by volume to 70% by volume. A temperature-sensitive radiative cooling film manufactured from the temperature-sensitive radiative cooling material of any one of claims 1 to 10. A method for manufacturing the temperature-sensitive radiation cooling film of claim 11, comprising:
Preparing a coating solution by mixing the matrix polymer, the hollow inorganic particles, the thermochromic particles, and a curing agent;
Applying the prepared coating solution to an object to be treated or an upper base layer using a wet coating process; and
A method of manufacturing a temperature-sensitive radiation cooling film comprising: forming a film through a curing process. According to clause 12,
The step of forming the film is performed using a wet coating process such as bar coating, doctor-blade coating, slot-die coating, and roll-to-roll coating. A method of manufacturing a temperature-sensitive radiative cooling film, characterized in that it is formed in the form of a film by curing the coating liquid applied on the object to be treated or on the top of the base layer.