High-transmission ultra-thin film having efficient broadband radiation and diffuse reflection through application of solution process and manufacturing method therefor

Abstract

The present invention relates to a high-transmission ultra-thin film and a manufacturing method therefor, the high-transmission ultra-thin film comprising: an absorption layer comprising a conjugated polymer; and a reflection layer comprising inorganic nanoparticles. The present invention can achieve broadband radiation and diffuse reflection characteristics enabling passive reduction of the internal temperature while maintaining transparency by using a water-dispersed organic-inorganic hybrid film based on a transparent and infrared emitting polymer.

Description

High-transmittance ultra-thin film with efficient broadband radiation and diffuse reflection by applying solution process and method for manufacturing the same

[0001] The present invention relates to a high-transmittance ultra-thin film having broadband radiation and diffuse reflection and a method for producing the same.

[0002] In recent years, concerns have grown about the detrimental environmental impacts of rapid industrialization and population growth. The overuse of fossil fuels has led to serious environmental pollution, including ozone layer destruction and excessive carbon dioxide emissions, which has led to a 2 to 6°C increase in global average temperatures during the 21st century. Despite the efforts of the International Environment Organization (IEO), a clear solution to global warming has yet to be found. Rising temperatures have significant implications for various industrial and transportation sectors, as well as for temperature control within buildings and vehicles. Energy consumption in these sectors accounts for more than 50% of total energy consumption.

[0003] To prevent energy loss, researchers have developed active and passive energy-saving methods. Passive methods, such as blocking near-infrared (NIR) radiation through reflection and absorption, hold promise. Blocking NIR, which accounts for approximately 52% of thermal energy, helps lower internal temperatures. Research is currently underway to achieve this by absorbing solar energy through reflection of NIR, mid-infrared, and far-infrared radiation, and forming a heat shield. Some research teams utilize cesium oxide (CWO) for NIR shielding due to its strong plasmon resonance absorption in the NIR range. These teams have modified and dispersed CWO in various materials to improve its dispersibility, transmittance, and temperature reduction performance. However, some of these studies are limited by measurement and manufacturing challenges, while others demonstrate opacity, which limits their potential applications. In addition, while existing NIR absorbing materials such as CWO have high blocking rates for the NIR range of 0.78 to 2.5 μm, their low MIR and FIR emissivity causes interference with the internal temperature due to increased surface energy of the film (Japanese Patent Application Laid-Open No. 2004-359811).

[0004] Furthermore, the researchers of the present invention explored films capable of dissipating and reflecting heat in the UV-Vis-NIR range, effectively reducing temperature by reflecting solar radiation, using various materials such as silica, polyethylene, and aluminum. However, these films are opaque or have low transmittance, limiting their use as heat shielding films. Furthermore, due to the principle of total internal reflection, they can reflect solar radiation energy from nearby buildings, potentially causing secondary light pollution.

[0005] Accordingly, the researchers of the present invention completed the present invention by producing a high-transmittance ultra-thin film using a one-pot process in which a transparent diffuse reflection layer and an absorption layer are created through self-assembly through phase separation of components within the film.

[0006] The present invention aims to provide a high-transmittance ultra-thin film and a method for manufacturing the same, which can prevent the film from being easily heated by the outside due to its broadband radiation and diffuse reflection characteristics that can passively lower the internal temperature by blocking external heat while maintaining transparency using a water-dispersible organic-inorganic hybrid film based on a transparent and infrared-emitting polymer, and which can maintain the internal temperature when the internal temperature is increased for insulation.

[0007] The present invention provides a high-transmittance ultra-thin film comprising an absorption layer comprising a conjugated polymer; and a reflective layer comprising colloidal silica.

[0008] In addition, the present invention provides a method for manufacturing a high-transmittance ultra-thin film, comprising the steps of: applying a certain amount of a solution containing a conjugated polymer and colloidal silica to a substrate; forming an absorption layer and a reflective layer; and curing the stabilized solution.

[0009] The high-transmittance ultra-thin film according to the present invention maintains transparency, and is effective in heat blocking because it can reduce the surface and internal temperature of the film by forming a reflective layer and an absorption layer.

[0010] It does not require organic solvents harmful to the human body or complex patterning processes, and can be manufactured through a one-pot wet coating process by forming a reflective layer and an absorbing layer through self-assembly induced by phase separation due to density differences, so the manufacturing method is simple and the process cost can be reduced, and large-area coating or mass production processes are possible.

[0011] FIG. 1(a) is an exemplary diagram of a method for manufacturing a high-transmittance ultra-thin film performed in a one-pot manner according to one embodiment, FIG. 1(b) is an exemplary diagram of solar radiation heat reflection and absorption of a high-transmittance ultra-thin film, FIG. 1(c) is an actual photograph of a high-transmittance ultra-thin film according to one embodiment, and FIG. 1(d) is an exemplary diagram of a passive daytime radiant cooling (PDRC) mechanism of a high-transmittance ultra-thin film.

[0012] Figure 2 is a graph showing the results of analysis of optical properties (Figures 2(a)-(b)) and structural changes (Figures 2(c)-(d)) for transmittance and mid-IR emissivity according to pH of a conjugated polymer.

[0013] Fig. 3(a) is a UV and IR spectrum of CWO, Fig. 3(b) is a UV and IR spectrum of TIEP, Fig. 3(c) is a graph of NIR absorption and emissivity results according to the coating thickness of CWO, Fig. 3(d) is a graph of NIR absorption and emissivity results according to the coating thickness of TIEP, and Fig. 3(e) is a graph of NIR absorption and transmittance results of CWO and TIEP.

[0014] Fig. 4(a) is a schematic diagram showing changes in diffuse reflection according to control of the thickness of the reflective layer coating, Fig. 4(b) is an actual photograph of a film on which a reflective layer is formed, Fig. 4(c) is a graph showing the results of a diffuse reflection analysis according to the thickness of the reflective layer coating, and Fig. 4(d) is a graph showing the results of a surface roughness analysis according to the degree of diffuse reflection.

[0015] Figure 5 is a graph showing the results of analysis of surface and internal temperature changes of TIEP, CWO, and silica according to dry thickness.

[0016] Fig. 6(a) is an example of a sample preparation process for SEM analysis according to Experimental Example 6, and Figs. 6(b)-(e) are cross-section, plane, bottom, and EDS images of a TIEP film photographed by SEM.

[0017] Figures 7(a)-(b) are graphs showing changes in transmittance, NIR absorption and diffuse reflection according to the thickness of S-TIEP-100, 200, 300, and 400, and the results of analysis of emissivity, Figure 7(c) is a graph showing the results of analysis of surface and internal temperatures of silica, TIEP, and S-TIEP-400, and Figure 7(d) is a graph showing the results of analysis of weighted average heat shielding efficiency and transparency considering various factors such as absorption, reflection, emissivity, and transmittance.

[0018] Figures 8(a)-(b) are examples showing how heat is blocked when CWO film and S-TIEP-400 film are applied, and Figures 8(c)-(d) are actual photographs and temperature change results graphs showing the temperature inside the box measured after exposing the box to which each film was applied outdoors.

[0019] Figures 9(a)-(b) are graphs and results of applying S-TIEP-400 according to the present invention to an agricultural house.

[0020] Figures 10(a)-(b) are graphs and results of applying S-TIEP-400 according to the present invention as an aluminum coating material for construction.

[0021] Figures 11(a)-(b) are graphs and results of applying S-TIEP-400 according to the present invention as a material for a means of transportation (automobile console box coating).

[0022] Figure 12 is a graph and result of applying S-TIEP-400 according to the present invention as a material for a moving vehicle (applied to a head up display).

[0023] Figure 13 is a graph and result of applying S-TIEP-400 according to the present invention as a coating material for fiber.

[0024] Figures 14 and 15 are graphs and results of applying S-TIEP-400 according to the present invention to a sample made of glass before applying it to an actual building.

[0025] Figures 16(a)-(b) are photographs and schematic diagrams showing S-TIEP-400 according to the present invention applied to an actual building.

[0026] Figures 17(a)-(b) and 18(a)-(b) are graphs and results of applying S-TIEP-400 according to the present invention to an actual building (building 1).

[0027] Figures 19(a)-(b) and 20(a)-(b) are graphs and results of applying S-TIEP-400 according to the present invention to an actual building (building 2).

[0028] Figure 21 is a spectrum graph of S-TIEP-400 according to the present invention.

[0029] The present invention is susceptible to various modifications and various forms. The specific examples and descriptions set forth below are intended solely to aid understanding of the present invention and are not intended to limit the invention to any specific disclosed form. The scope of the present invention should be understood to encompass all modifications, equivalents, and alternatives falling within the spirit and technical scope of the present invention.

[0030] Unless otherwise indicated herein, % means weight %. In addition, unless otherwise indicated, weight % means weight % in the total composition including all components.

[0031] Hereinafter, the present invention will be described in detail.

[0032] The present invention relates to a high-transmittance ultra-thin film that is effective in controlling internal temperature, exhibits a transmittance of 80% or more, and has an internal temperature lowering mechanism.

[0033] The present invention provides a high-transmittance ultra-thin film comprising an absorption layer comprising a conjugated polymer; and a reflective layer comprising inorganic nanoparticles.

[0034] The above inorganic nanoparticles may include one or more selected from the group consisting of silica, zinc oxide, titanium dioxide, silver, and gold. The silica may be in the form of colloidal silica.

[0035] In one embodiment, the synthesized S-TIEP as shown in Fig. 1(a) can be manufactured in one pot using a simple bar coating method, and it was confirmed that the manufactured film was in the form of a very transparent ultra-thin film as shown in Fig. 1(c).

[0036] In Fig. 1b, the structure of a multilayer in which an absorbing layer and a reflecting layer are formed within an S-TIEP film formed through phase separation-induced self-assembly can be confirmed, and the heat flux time delay phenomenon due to the heat capacity and emissivity through the solar energy transfer process (reflection, absorption, and emission) as in Fig. 1d can be shown. Here, P sun is the introduced solar power, and R reflection refers to specular and diffuse reflection in the wavelength range of 0.2 to 2.5 μm.

[0037] The above conjugated polymers can be used as highly transparent emitters for near infrared (NIR) absorption, mid infrared (MIR) and far infrared (FIR) radiation.

[0038] In the present invention, the conjugated polymer includes at least one selected from the group consisting of polythiophene, polyalkylthiophene, polyaniline, polyfluorene, polyparaphenylenevinylene, polyphenylene, polyparaphenylene, polydialkylfluorene, polyfluorenebenzothiadiazole, and derivatives thereof.

[0039] The present invention optimizes the optical properties of a film by using a conjugated polymer with a controlled oxidation level, as shown in the results of Experimental Example 1 (Figs. 2(a) and 2(b)). In particular, it was confirmed that as the oxidation level increases, both the transmittance in the visible light range and the emissivity in the mid-infrared range simultaneously improve.

[0040] The above inorganic nanoparticles can exhibit a diffuse reflection effect by controlling the shape of the film, and for this purpose, they can be included in an amount of 5 to 50 wt% based on the total weight of the film before drying. The inorganic nanoparticles can be included in an amount of 9 to 45 wt%, 5 to 15 wt%, 15 to 25 wt%, 25 to 35 wt%, or 35 to 45 wt% based on the total weight of the film before drying. The inorganic nanoparticles can be colloidal silica.

[0041] Conventional NIR absorbing materials, such as CWO, exhibit high blocking rates in the NIR range of 0.78 to 2.5 μm. However, their low MIR and FIR emissivity increase the film's surface energy, causing interference with internal temperature. Therefore, the absorption and emissivity properties of the conjugated polymer and the diffuse reflection of colloidal silica were maximized to induce a synergistic heat blocking effect.

[0042] In the present invention, the absorption layer and the reflection layer are formed through phase separation-induced self-assembly of a conjugated polymer and inorganic nanoparticles.

[0043] The high-transmittance ultra-thin film of the present invention can selectively control the transmittance in the visible light region and the blocking rate in the near-infrared region depending on the thickness of the coated film. The transmittance in the visible light region and the blocking rate in the near-infrared region can also be selectively controlled depending on the composition of the coating solution composition used to manufacture the transparent film.

[0044] In the present invention, the thickness of the high-transmittance ultra-thin film can maximize the improvement effect of internal temperature reduction according to transmittance, heat blocking, and emissivity when it is 1400 to 2300 nm. The thickness of the absorption layer can be 100 to 500 nm, and the thickness of the reflective layer can be 1300 to 1800 nm. In the above high-transmittance ultra-thin film, the absorption layer including the conjugated polymer may have a thickness of 50 to 550 nm, 80 to 500 nm, 100 to 450 nm, 50 to 150 nm, 150 to 250 nm, 250 to 350 nm, or 350 to 450 nm, and the reflection layer including inorganic nanoparticles may have a thickness of the entire thickness of the high-transmittance ultra-thin film excluding the absorption layer, but is not limited thereto, and may be adjusted according to desired transmittance, heat blocking and emissivity, and intended use. In one embodiment of the present invention, the absorption layer may have a thickness of 100 nm, 200 nm, 300 nm, and 400 nm, and the reflection layer may have a thickness of 1500 nm and include colloidal silica. In this case, the thickness of the film refers to the thickness of the film after curing and / or drying after bar coating using a solution including the conjugated polymer and the inorganic nanoparticles.

[0045] Specifically, when the thickness of the high-transmittance ultra-thin film is 1400 to 2300 nm, the transmittance for light, specifically, the transmittance for light with a wavelength of 400 to 750 nm, is 80% or more.

[0046] Specifically, when the thickness of the high-transmittance ultra-thin film is 1400 to 2300 nm, the reflectivity is 25% or more.

[0047] The high-transmittance ultra-thin film of the present invention can realize excellent heat blocking, infrared absorption, and visible light transmission effects with a multi-layer structure formed of a reflective layer and an absorbing layer. In the high-transmittance ultra-thin film of the present invention, for example, a multi-layer formed of an emitting layer and an absorbing layer can be regularly formed in an alternating order of a first reflective layer, a first absorbing layer, a second reflective layer, and a second absorbing layer, or the emitting layer and the absorbing layer can be formed in an order in which the first reflective layer, the first absorbing layer, the second absorbing layer, and the second reflective layer or the absorbing layer are repeatedly present. There may be a void between the emitting layer and the absorbing layer.

[0048] The above film can be manufactured and used by adjusting the content of the conjugated polymer and the thickness of the film layer to have a visible light transmittance and a near-infrared light blocking rate suitable for the intended use.

[0049] Accordingly, it can be used as a transparent film by not only blocking light in the near-infrared region but also transmitting visible light.

[0050] In addition, the present invention provides a method for manufacturing a high-transmittance ultra-thin film, comprising the steps of: applying a certain amount of a solution containing a conjugated polymer and inorganic nanoparticles to a substrate; forming an absorption layer and a reflective layer; and curing the stabilized solution.

[0051] The above inorganic nanoparticles may include one or more selected from the group consisting of silica, zinc oxide, titanium dioxide, silver, and gold. The silica may be in the form of colloidal silica.

[0052] Conventional film manufacturing methods primarily utilize toxic solvents such as methyl ethyl ketone or toluene. However, the film manufacturing method according to the present invention can be easily performed without the use of toxic solvents. Although not limited thereto, deionized water and ethanol can be used as solvents.

[0053] The high-transmittance ultra-thin film according to the present invention can have various forms. The high-transmittance ultra-thin film can be formed solely from a solution containing a conjugated polymer and inorganic nanoparticles without a substrate, or can be formed by coating a solution containing a conjugated polymer and inorganic nanoparticles on a substrate, but is not limited thereto.

[0054] In the present invention, a high-transmittance ultra-thin film can be formed into a multilayer structure in which an absorption layer and a reflection layer are formed as a cured product of a solution containing a conjugated polymer and inorganic nanoparticles.

[0055] In one specific example, the substrate in the applying step may be a transparent film such as PET, PE, PVC, or a glass material, and any material that does not react with the solution, can be coated on the substrate, and can smoothly separate the dried film may be used.

[0056] In the above-described applying step, the solution contains at least one conjugated polymer selected from the group consisting of polythiophene, polyalkylthiophene, polyaniline, polyfluorene, polyparaphenylenevinylene, polyphenylene, polyparaphenylene, polydialkylfluorene, polyfluorenebenzothiadiazole, and derivatives thereof.

[0057] In the above-described applying step, the solution contains 5 to 20 wt% of inorganic nanoparticles based on the total weight.

[0058] The step of forming the above absorption layer and reflection layer includes a step of forming the absorption layer and reflection layer through phase separation-induced self-assembly of a conjugated polymer and inorganic nanoparticles.

[0059] In one specific embodiment, the coating step may be performed by bar coating, spin coating, or spray coating. Since the present invention enables coating through a simple method such as bar coating, the manufacturing process is simple, and since no separate additives for absorbing near-infrared light other than the conjugated polymer and colloidal silica are required, it is excellent in terms of cost-effectiveness.

[0060] The high-transmittance ultra-thin film according to the present invention can be used as, but is not limited to, an exterior material for a building, a coating agent for an exterior material for a building, a coating agent for architectural glass, a glass coating agent, a film, a fiber coating agent, an exterior material for a vehicle, a coating agent for an exterior material for a vehicle, an interior material for a vehicle, a coating agent for an interior material for a vehicle, agricultural materials, and mobile materials. The usefulness of the above-mentioned applications was confirmed in the following examples.

[0061]

[0062] Hereinafter, the present invention will be described in detail through examples. The following examples are intended to illustrate the present invention and are not intended to limit its scope. These examples are provided to ensure a complete disclosure of the present invention and to fully inform those skilled in the art of the invention of its scope. The present invention is defined solely by the scope of the claims.

[0063]

[0064] Manufacturing Example 1. Manufacturing of conjugated polymer

[0065] 1-0. Materials

[0066] 3,4-Ethylenedioxythiophene (EDOT, 97%), iron(III) sulfate (Fe2(SO4)3, 97%), sodium persulfate (Na2S2O8, 99.0%), cation exchange resin, and anion exchange resin were purchased from Sigma-Aldrich (Korea). Sulfuric acid solution (H2SO4) was purchased from Deoksan Chemical (Korea). All reagents were used as received without any additional purification process. Distilled water was used in all experiments, and LUDOX ® AS 40 colloidal silica was purchased from Sigma Aldrich (St. Louis, MO, USA), and bare PET film (120 μm) was purchased from Toray Chemical (Korea).

[0067] 1-1. Synthesis of conjugated polymers

[0068] First, a conjugated polymer was synthesized and prepared. The conjugated polymer was prepared using the following method.

[0069] Polystyrene sulfonic acid (PSS) 21.75 g (Mw: 75,000) was dissolved in 670 g of distilled water and stirred for 1 hour. Then, 0.086 g of iron sulfate was added and stirred until dissolved. During stirring, nitrogen was introduced into the solution for 1 hour. When the iron sulfate was completely dissolved, the temperature of the solution was lowered to 10℃, 2.610 g of 3,4-ethylenedioxythiophene (EDOT) monomer was added, and 30 g of an aqueous solution containing 5.022 g of sodium persulfate was added. Then, after polymerization reaction was carried out for 24 hours, 500 ml of mixed ion exchange resin in which cation exchange resin and anion exchange resin were mixed in a 1:1 ratio was added to remove unnecessary ions, thereby producing a PEDOT:PSS polymer solution.

[0070] The synthesized conjugated polymer was adjusted to pH 1 to 11 by a method well known in the art.

[0071] Experimental Example 1. Optimization of the optical properties of conjugated polymers

[0072] Experiments were conducted to determine whether the optical properties of conjugated polymers can be controlled depending on the oxidation level.

[0073] Specifically, conjugated polymers (absorbing layer of the present invention, TIEP) synthesized in Manufacturing Example 1-1 at pHs of 1, 2, 3, 5, 8, and 11 were prepared. The infrared spectrum was measured in TR mode using an FT-IR spectrometer (Bruker, model Vertex 70, Billerica, MA, USA), the UV-Vis NIR transmittance of the thin film was measured using a spectrophotometer (JASCO Corporation model V 770), and the change in the conjugated polymer chain structure was analyzed using Raman spectroscopy (LabRAM Aramis, Horiba Jobin Yvon, NJ, USA) using a 633 nm He-Ne laser as an excitation source. The results are shown in Table 1 and Fig. 2 below.

[0074] Sample pH Transmittance (%) Mid-IR Emissivity (2.5-25 ㎛) Work Function Visible Light (0.4-0.75 ㎛) Near-IR (0.75-2.5 ㎛) Heat Blocking Efficiency (0.75-2.5 ㎛) pH 1 66.14 2 0.26 6 1.88 9 9.40 5.21 pH 2 67.14 2 2.16 6 2.83 9 8.89 4.82 pH 3 66.22 2 3.47 6 2.5 49 8.92 pH 5 64.84 2 4.34 6 3.43 9 8.41 4.53 pH 8 64.78 27.28 6 1.83 9 8.08 pH 1 1.58 43 3.6 1.59 74 9 6.87 4.46

[0075] As shown in Table 1 and Figure 2, it was confirmed that both the transmittance in the visible range and the emissivity in the mid-infrared range simultaneously improved as the oxidation level increased. Furthermore, it was also confirmed that the shielding rate in the near-infrared increased as the oxidation level increased. Consistent with the results of reported Raman studies on doped conjugated polymers, a broadening of the peak was observed as the oxidation level increased. Therefore, the optical properties of films can be optimized by using the conjugated polymer with a controlled oxidation level (TIEP) of the present invention.

[0076] According to the results of Experimental Example 1, a high-transmittance ultra-thin film was manufactured by controlling the oxidation level to pH 1 in the following manufacturing example.

[0077] Manufacturing Example 2. Manufacturing of a high-transmittance ultra-thin film

[0078] The conjugated polymer (TIEP) solution synthesized in the above Manufacturing Example 1 and the colloidal silica solids solution of 10% to 40% were mixed at a volume ratio of 1:9 (10 ml + 90 ml) at 70°C for 10 minutes, and 0.05% of a thickener was added and mixed for 60 minutes. After that, the PET film was subjected to plasma treatment 5 times to secure a surface energy of 30 dynes or more, and the solution was coated with a bar coater and cured in a convection oven at 130°C for 3 minutes.

[0079] Experimental Example 2. Analysis of the optical properties of a high-transmittance ultra-thin film.

[0080] Experiments were conducted to compare the optical properties of films according to thickness.

[0081] Specifically, an absorption layer (TIEP) film was prepared using a conjugated polymer whose oxidation level was controlled to pH 1 in Manufacturing Example 1-1. The optical properties were analyzed in the same manner as in Experimental Example 1, and the results are shown in Table 2 and Figure 3 below.

[0082] Sample Thickness (nm) Transmittance (%) (0.4-0.78 ㎛) Absorption (%) (0.78-2.5 ㎛) Emissivity (%) (2.5-25 ㎛) Diffuse Reflectance (%) (0.2-2.5 ㎛) TIEP1009026.275.92.872009037.381.73.25008471.196.93.48007483.498.93.515006694.199.83.6 CWO1009617.19.63.12009319.410.53.25008833.213.23.28008248.217.43.415007269.319.53.4

[0083] In Fig. 3, the yellow area represents the transmittance (%) in the visible light range of 0.4 to 0.78 μm, the red area represents the absorption (%) in the NIR range of 0.78 to 2.5 μm, and the green area represents the emissivity (%) in the MIR range of 2.5 to 25 μm.

[0084] The above TIEP (conjugated polymer solution manufactured by controlling the oxidation level to pH 1 in Manufacturing Example 1-1) and cesium oxide (CWO, 23% solid content solution) samples were manufactured by coating each solution on a polyethylene terephthalate (PET) substrate (100 μm) with a bar coater and then curing in a convection oven at a temperature of 80 to 100°C for 1 to 3 minutes. The above thickness refers to the dry thickness.

[0085] As shown in Table 2 and Fig. 3, as the dry thickness of cesium oxide (CWO) increased from 100 nm to 1500 nm, the transmittance (%) decreased from 96% to 72%, the absorption (%) increased from 17.1% to 69.3%, and the emissivity (%) increased from 9.6% to 19.5%. In addition, the heat capacity was confirmed to be 2.54 J / g·℃ at 34.33℃. In the case of TIEP, as the dry thickness increased from 100 nm to 1500 nm, the transmittance decreased from 90% to 66%, while the absorption increased from 26.2% to 94.1%, and the emissivity increased from 75.9% to 99.8%. The heat capacity was also confirmed to be 1.18 J / g·℃ at 25℃. Based on the above results, the absorptivity of CWO increased dramatically from 17.1% to a maximum of 69.3%, while the emissivity increased slightly from 9.6% to 19.5%. These results confirm that when the absorbed energy exceeds the emitted energy, the surface temperature increases when exposed to light energy. Furthermore, a higher heat capacity leads to a higher peak surface temperature.

[0086] In contrast, the absorptivity of TIEP increased rapidly from 26.2% to a maximum of 94.1%, while the emissivity increased from 75.9% to 99.8%. For TIEP, the emissivity value was always higher than the NIR absorption value at the same dry thickness, and this difference resulted in a lower surface temperature when exposed to light energy compared to CWO. Furthermore, the peak surface energy temperature was lower due to the lower heat capacity.

[0087] Figure 3(e) shows the NIR absorption and transmittance of CWO and TIEP under transparent conditions to investigate the NIR absorption values ​​of each material. The results show that TIEP exhibited a higher NIR absorption than CWO, with NIR absorption 13% and 11% higher than the transmittance of 90% and 80%, respectively. Furthermore, the difference in NIR absorption decreased as the transmittance gradually decreased, and the NIR absorption value of CWO increased starting from the transmittance of 28%. This is because the NIR absorption of TIEP increased with dry thickness more than that of CWO.

[0088] Experimental Example 3. Diffuse Reflection and Surface Analysis of Colloidal Silica

[0089] An experiment was conducted to verify whether diffuse reflection could be controlled by adjusting the silica thickness, as shown in Fig. 4(a).

[0090] Specifically, a colloidal silica solids solution of 10 to 40% was coated on a polyethylene terephthalate (PET) substrate (100 μm) using a bar coater and then cured in a convection oven at a temperature of 80 to 100°C for 1 to 3 minutes to produce a film. The produced silica coating film had a dry thickness of 100 to 1500 nm. The diffuse reflection of the film was analyzed by the specular component exclusion (SCE) method using an integrating sphere of a UV-Vis spectrophotometer. The results are shown in Fig. 4.

[0091] In Fig. 4(b), the film maintained transparency and flexibility without cracking or peeling.

[0092] As shown in Fig. 4(c), as the dry thickness increased from 100 nm to 1500 nm, the diffuse reflection gradually increased from 11% to 25%, and a decrease in slope was observed at 800 nm (from the lowest curve, PET, silica 100 nm, and sequentially from 200 nm to 1500 nm). Furthermore, the NIR absorption was 0%, and the emissivity was less than 5%, regardless of the coating thickness. Therefore, it can be seen that the temperature reduction mechanism of silica is mainly diffuse reflection.

[0093] In Fig. 4(d), low surface roughness was observed at 100 nm, while high surface roughness was observed at 1500 nm.

[0094] Experimental Example 4. Analysis of Film Surface and Internal Temperature

[0095] The surface and temperature of the CWO, silica, and TIEP films manufactured in the same manner as in Experimental Examples 2 and 3 were analyzed according to the dry thickness. To this end, a thermometer was attached to the surface and the center of the interior to analyze the surface temperature and internal temperature of the greenhouse model installed as shown in Fig. 5(a). After that, two types of lamps, a xenon lamp and an infrared lamp, were used simultaneously to monitor the temperature change. The reason for this is that the xenon lamp has a wavelength of 400 to 1100 nm, and the infrared lamp has a wavelength of 700 to 2500 nm, making it suitable for reproducing solar energy. In addition, the amount of light reaching the surface at noon, the hottest time in midsummer, is 1000 w / m 2 The temperature change was analyzed. The results are shown in Fig. 5.

[0096] The surface temperature of the PET film was analyzed to be 33.0℃ for 1 hour.

[0097] In Fig. 5(b), the surface temperatures of CWO at 100, 200, 500, 800, and 1500 nm were 37.9, 40.9, 44.9, 46.8, and 49.1℃, respectively. Furthermore, the surface temperature gradually increased as the drying thickness increased. This is because, as shown in Fig. 3(c), the near-infrared absorption was higher than the emissivity at all drying thicknesses. This indicates that the surface temperature increased because the amount of absorbed light energy was greater than the amount of emitted light energy. For the absorbing layer, the surface temperatures were analyzed to be 33.0, 33.7, 34.0, 42.1, and 44.2℃ at 100, 200, 500, 800, and 1500 nm, respectively, which were lower than those of CWO at the same thickness at 100, 200, 500, 800, and 1500 nm, respectively. In addition, at relatively thin thicknesses of 100, 200, and 500 nm, surface temperatures similar to those of the reference PET film were measured, but at thicknesses of 800 nm or more, the surface temperature increased rapidly. This is because, as can be seen in Fig. 3(d), the emissivity did not increase significantly from 96.9% to 500 nm or more. However, the NIR absorption increased significantly from 83.4% at 800 nm to 94.1% at 1500 nm, resulting in a rapid increase in the surface temperature at a dry thickness of 800 nm. In contrast, the surface temperature of silica decreased with increasing dry thickness, reaching values ​​of 31.9, 30.8, 29.9, 29.8, and 28.7°C at 100, 200, 500, 800, and 1500 nm, respectively. The surface temperature decreased as diffuse reflectance increased. Therefore, CWO and the conjugated polymer absorb NIR radiation, increasing the surface temperature. However, due to its higher emissivity (%), the conjugated polymer had a lower surface temperature than CWO.

[0098] Additionally, the surface temperature of silica decreases due to diffuse reflection, indicating that the properties of this material can be utilized for surface temperature control. Figure 5c shows the change in internal temperature over 1 hour as the dry thickness of the conjugated polymer, CWO, and silica varies from 100 to 1500 nm. The internal temperature of the reference PET film was analyzed to be 39.1°C for 1 hour. For CWO, the internal temperatures at 100, 200, 500, 800, and 1500 nm were 37.0, 34.9, 30.9, 29.8, and 27.8°C, respectively, and the internal temperature gradually decreased as the dry thickness increased. This is because the light energy is blocked from entering the film by NIR absorption. Analysis of the conjugated polymer at wavelengths of 100 nm (34.0°C), 200 nm (32.0°C), and 1500 nm (23.0°C) revealed that the internal temperature gradually decreased with increasing dry thickness, with a maximum decrease of 16.1°C compared to the internal temperature of the reference PET film, and a lower internal temperature was observed at the same thickness compared to CTO. This is because the surface temperature is lowered due to the high NIR absorptivity and high emissivity (%).

[0099] Experimental Example 5. SEM image confirmation of a high-transmittance ultra-thin film.

[0100] To confirm whether an absorption layer and a reflective layer were formed in the high-transmittance ultra-thin film manufactured in Manufacturing Example 2, an SEM analysis was performed. The results are shown in Fig. 6.

[0101] The cross-sectional view of the S-TIEP in Fig. 6(b) confirms that it consists of a diffuse reflection layer made of silica and a highly transparent absorbing layer made of a conjugated polymer. The observed image is due to a phase separation phenomenon in which the silica migrates to the top and the conjugated polymer migrates to the bottom due to the difference in density between the silica and the conjugated polymer used in the diffuse reflection layer and the highly transparent absorbing layer, respectively, during self-assembly. This layer separation is also confirmed in Figs. 6(c) and (d), which show the top and bottom views of the diffuse reflection layer and the transparent absorbing layer, respectively. In addition, the formation of two layers was confirmed through EDS analysis in Fig. 6(e).

[0102] Experimental Example 6. Temperature Analysis of S-TIEP Film

[0103] Based on the above analysis results, the thickness of the transparent absorption layer was adjusted to 100, 200, 300, and 400 nm within the range of 80% transmittance, and the diffuse reflection layer was fixed at 1500 nm. Each sample was manufactured as follows.

[0104] S-TIEP-100

[0105] The conjugated polymer (TIEP) solution synthesized in the above manufacturing example 1 and the colloidal silica solution having a solid content of 10% are mixed in a volume ratio of 1:9 (10 ml + 90 ml) at 70°C for 10 minutes, and 0.05% of a thickener is added and mixed for 60 minutes.

[0106] S-TIEP-200

[0107] The conjugated polymer (TIEP) solution synthesized in the above manufacturing example 1 and the colloidal silica solution having a solid content of 20% are mixed in a volume ratio of 1:9 (10 ml + 90 ml) at 70°C for 10 minutes, and 0.05% of a thickener is added and mixed for 60 minutes.

[0108] S-TIEP-300

[0109] The conjugated polymer (TIEP) solution synthesized in the above manufacturing example 1 and the colloidal silica solution having a solid content of 30% are mixed in a volume ratio of 1:9 (10 ml + 90 ml) at 70°C for 10 minutes, and 0.05% of a thickener is added and mixed for 60 minutes.

[0110] S-TIEP-400

[0111] The conjugated polymer (TIEP) solution synthesized in the above manufacturing example 1 and the colloidal silica solution having a solid content of 40% are mixed in a volume ratio of 1:9 (10 ml + 90 ml) at 70°C for 10 minutes, and 0.05% of a thickener is added and mixed for 60 minutes.

[0112] The thickness of the absorbent layer can be adjusted by varying the content ratio of the conjugated polymer solution (as prepared in Preparation Example 1-1) and colloidal silica (as prepared in the above preparation method) in the coating solution. The film was prepared using the same substrate, coating method, and drying conditions as those used to prepare the samples in the above experimental examples. The temperature of the S-TIEP film was analyzed and is shown in Table 3 and Fig. 7 below.

[0113] Sample name Thickness (nm) Diffuse reflectance (%) NIR absorption (%) Emissivity (%) Absorption layer Diffuse reflectance layer S-TIEP-100 100 1500 25 1975 S-TIEP-200 200 4481 S-TIEP-300 300 5288 S-TIEP-400 400 6395

[0114] The transparent temperature ranges are shown in Table 3 and Fig. 7. As a result, the transmittance decreased to 90, 88, 85, and 80%, the NIR absorption increased to 19, 44, 52, and 63%, and the emissivity increased to 75, 81, 88, and 95%. In addition, the diffuse reflectance at 1500 nm was confirmed to be 27%. The surface temperatures of silica, TIEP, and S-TIEP were confirmed to be 29, 35, and 34°C, respectively, and the internal temperatures were found to be 36, 28, and 26°C.

[0115] Figure 7(d) compares the weighted average heat-shielding efficiency with recent literature results considering various factors such as absorption, reflection, emissivity, and transmittance. Studies applying the PDRC concept showed that the maximum weighted average heat-shielding efficiency reached 95% due to high reflectivity and emissivity. However, these films tended to be opaque or had a transmittance of less than 20%. Even a slight increase in transmittance significantly reduced the weighted average heat-shielding efficiency. Studies focusing on NIR absorption achieved a high transmittance of up to 80%. However, due to low emissivity and reflection, the weighted average heat-shielding efficiency remained below 40%. The S-TIEP-400 fabricated in this study showed a transmittance of over 80% and high emissivity due to the hybridization of the near-infrared absorbing layer and the diffuse reflecting layer, confirming a weighted average heat-shielding efficiency of 81%.

[0116] As described above, studies on PDRC have revealed high HS efficiency and low transmittance due to the material's opaque nature. In this study, transmittance was improved by up to 80% compared to previously reported materials, while maintaining a high HS efficiency of 81% and transparency. Furthermore, applying the NIR absorption concept increases transmittance, but the rapid increase in surface temperature lowers HS efficiency. This study achieved up to a 55% increase in transmittance and a 61% increase in HS efficiency compared to previously reported results.

[0117] Experimental Example 7. Thermal Blocking Analysis of S-TIEP Film

[0118] Custom sealed transparent small dome (width X height X height = 6.5 X 30 X 5 cm) for manufacturing S-TIEP hybrid films. 3 ) was utilized. The dome was designed in the shape of a greenhouse, and a thermometer was placed inside to measure temperature changes.

[0119] An external temperature experiment was conducted to analyze the internal temperature of a greenhouse dome fabricated using PET, CWO, and S-TIEP-400 films (same as those manufactured and used in the experimental examples above) over a period of one day. The results are shown in Fig. 8.

[0120] In Fig. 8(d), between 10:00 and 13:00, the temperature experienced a rapid increase in all three samples, PET, CWO, and S-TIEP-400, reaching peaks of 54.3, 56.5, and 46.4℃ at 13:00, respectively. Thereafter, the internal temperature gradually decreased from 13:00 to 15:00. In particular, CWO showed a maximum temperature that was 2.2℃ higher than the reference temperature, while S-TIEP-400 showed a maximum temperature that was 7.9℃ lower than the reference temperature. The temperature difference between CWO and S-TIEP-400 was 10.1℃, indicating that S-TIEP-400 had a lower temperature than CWO. The observed temperature change is due to interference due to the surface temperature difference, as shown in Fig. 8(a). This phenomenon occurred because of its high heat capacity and low emissivity compared to NIR absorptivity. Specifically, CWO complied with the given conditions and showed an increase in its internal temperature compared to the reference temperature. Conversely, the S-TIEP-400, with its low thermal capacity, can partially scatter solar radiation and absorb some NIR radiation. Furthermore, as shown in Figure 8(b), the higher the emissivity, the lower the internal temperature compared to the reference.

[0121] Experimental Example 8. Analysis of heat blocking when applying S-TIEP film to various situations.

[0122] Experimental Example 8-1. Application as an agricultural material

[0123] To verify whether the S-TIEP film of the present invention can be used as an agricultural material, it was applied to an actual agricultural greenhouse and crops were grown (Fig. 9).

[0124] An actual house was manufactured as shown in Fig. 9(a), and an open field without film was applied to the A zone house, a commercially available solarium film (Ilshin Chemical Industry Co., Ltd.) was applied to the B zone house, and an S-TIEP-400 sample film according to the present invention was applied to the C zone house.

[0125] As shown in Fig. 9(b), crops grew better and yields increased in the C Zone house where the S-TIEP-400 sample film according to the present invention was applied. Therefore, it is believed that the film can be applied as an agricultural material.

[0126] Experimental Example 8-2. Application as a coating material to architectural aluminum.

[0127] Architectural aluminum is susceptible to rapid temperature rises due to direct sunlight, particularly in summer, leading to rapid indoor temperature increases. To determine whether this drawback could be addressed, an aluminum (Al) plate was coated with black lacquer spray (paint) and then S-TIEP-400 was applied over the plate for testing (Fig. 10). In Fig. 10, the reference is an aluminum plate coated with black lacquer spray.

[0128] As shown in Fig. 10(a), S-TIEP-400 according to the present invention was coated on an aluminum material for construction, and as shown in Fig. 10(b), it can be confirmed that the temperature is significantly lower than that of an uncoated sample. Therefore, it is believed that it can be applied as a coating material for lowering the temperature of aluminum.

[0129] Experimental Example 8-4. Application as a material for transportation

[0130] The S-TIEP-400 material according to the present invention and a conventional commercially used PET material film (Ref) were coated on the console box of a vehicle and compared.

[0131] As shown in the graph in Figure 11, it was confirmed that there was a difference of 7℃ after 1 hour and a maximum difference of 7.7℃ after 5 hours.

[0132] Additionally, temperature changes were also confirmed when applied to the head-up display of a car (Fig. 12).

[0133] According to the present invention, 0.03 g and 0.05 g of H-HSCS (BYK) as a curing agent were added to the S-TIEP-400 material to manufacture H-HSCS_003 and H-HSCS_005 films, respectively. As a comparative sample, a CTO film (CTO applied to a PET substrate) was prepared.

[0134] In Fig. 12, for the internal film temperature, the PET film showed a temperature of 36.3°C, the CWO film showed a temperature of 30.5°C, the H-HSCS-003 film showed a temperature of 28.8°C, and the H-HSCS-005 film showed a temperature of 24.2°C, and for the film surface temperature, the PET film showed a temperature of 35°C, the CWO film showed a temperature of 41°C, the H-HSCS-003 film showed a temperature of 36.7°C, and the H-HSCS-005 film showed a temperature of 37.5°C. It was confirmed that lower internal and external temperatures were achieved in the film utilizing the S-TIEP-400 material according to the present invention.

[0135] Experimental Example 8-5. Application as a coating material for fibers

[0136] The S-TIEP-400 material according to the present invention was used to coat existing commercially used cotton fibers, and compared with uncoated cotton fibers (Ref. material) by heating and cooling.

[0137] Heating and cooling were performed under the following conditions.

[0138] Temperature measurements and analyses were performed using a solar simulator. The solar simulator simultaneously integrated xenon and infrared lamps based on the AM 1.5 global solar spectrum, which simulates summer noon. The intensity of the xenon lamp ranged from 800 to 1000 W / m over a wavelength range of 400 to 1100 nm.2 While the IR lamp can be adjusted to 50 W / m in the wavelength range of 700 to 2500 nm. 2 is emitted with an intensity of . This configuration enables the generation of radiation similar to actual solar radiation.

[0139] As shown in the graph in Fig. 13, in the temperature change experiment when coating the fiber, in the cooling experiment, an infrared lamp + xenon lamp were shined on the outside of the sample (the solar simulator method of Experimental Example 8-5) and the internal temperature change was measured. In the heating experiment, an infrared lamp (using the infrared lamp of Experimental Example 8-5) was turned on inside the sample and the temperature change was measured to determine the degree to which the internal temperature was kept warm. The Ref material was the same at 100.5℃ for both the cooling and heating experiments, and the S-TIEP-400 material according to the present invention had a heat retention ability greater than the Ref material in the heating experiment, and in the cooling experiment, it blocked external heat compared to the uncoated cotton material, so that the internal temperature of the sample was maintained at a low temperature.

[0140] Experimental Example 8-6. Application as a coating material for architectural glass.

[0141] In order to confirm whether the S-TIEP-400 film of the present invention can be used as a construction material, glass samples were produced and the temperature was confirmed (Figs. 14 to 20).

[0142] First, before applying it to an actual building, a sample made of glass was coated to confirm whether there would be a significant effect (Figs. 14 and 15).

[0143] As shown in Fig. 14, hexahedrons made of glass were manufactured, and each glass was manufactured as a double-layer glass (pair glass) in which two sheets of glass overlap each other, as shown in the lower right of Fig. 14.

[0144] As shown in the graph of Fig. 14, compared to the glass without any coating (55.4℃ at 180 minutes, 1. Ref. (general double-glazed glass) in Fig. 14), the glass to which the S-TIEP-400 film of the present invention was applied recorded a significantly lower temperature (42.6℃ at 180 minutes, Sample 2 in Fig. 14) when the solar simulator of Experimental Example 8-5 was applied for 180 minutes, confirming that external heat was significantly blocked (upper graph in Fig. 14). In addition, the internal temperature was analyzed to determine the degree of heat retention by turning on an infrared lamp (using the infrared lamp of Experimental Example 8-5) inside Sample 2 for 60 minutes, and similarly, compared to the glass without any coating (40.7℃), a higher temperature (1. Ref., 52℃) was recorded, confirming that the heat retention effect is also good (lower graph in Fig. 14).

[0145] Figure 15 shows the results of analyzing the internal temperature of a single-layer glass sample subjected to the external solar simulator of Experimental Example 8-5, after applying S-TIEP-400 to the single-layer glass, to determine the internal temperature change due to the thermal barrier coating. When applied to the single-layer glass sample, a temperature decrease of 17.7°C was observed compared to the uncoated sample (1. Ref. in Figure 14).

[0146] Through the above lab scale experiment, it was confirmed that the S-TIEP-400 film of the present invention can be used as a coating material for architectural glass materials, and experiments were conducted by coating it on an actual building (Figs. 16 to 20).

[0147] Using the S-TIEP-400 film, it was applied to an actual building as shown in Fig. 16. In the case of Building 1 (Seoul, Oryun Church) in Fig. 16(a), it was applied to a building with two glass sides as shown in the schematic diagram below, and in the case of Building 2 (G-flex Tower, Seoul) in Fig. 16(b), it was applied to a building with one glass side as shown in the schematic diagram below, and the cases of Reference (SK Company's heat-blocking film) film and S-TIEP-400 film were compared in the same building during the same period in midsummer.

[0148] In the case of Building 1, in the case of the existing commercially used Reference film (SK company heat-blocking film), the internal temperature rose to 40.5℃ (Fig. 17(a), Ref), but in the case of using the S-TIEP-400 film of the present invention, it was confirmed that 32.1℃ was recorded (Fig. 17(a)). In the case of the existing commercially used Reference film (SK company heat-blocking film), it was possible to block near-infrared rays (Fig. 17(b)), but over time, the temperature inside the building increased, and it was confirmed that the inside was hotter than the outside temperature (37℃) by 3.5℃. However, in the case of using the S-TIEP-400 film of the present invention, it was confirmed that it was significantly lower (32.1℃) than the outside temperature because it had high emissivity in addition to blocking near-infrared rays (lower graph of Fig. 17(b)). As a result, when the S-TIEP-400 film of the present invention is used, energy consumption can be reduced by up to 53% from 9:00 AM to 6:00 PM (graph and table in Fig. 18(a)). In addition, it can be confirmed that the S-TIEP-400 film has a high transmittance and is transparent, but has a high emissivity of up to 0.94 (Fig. 18(b)).

[0149] In the case of Building 2, it was confirmed that the internal temperature could be maintained lower than the outside temperature, despite the fact that the area of ​​the building glass to which the S-TIEP-400 film of the present invention was applied was smaller than that of Building 1. Similarly, in the case of the existing commercially available Reference film (SK's heat-blocking film), the outside temperature was higher than the internal temperature (Fig. 19). As a result, it was confirmed that when the S-TIEP-400 film of the present invention was used, energy consumption could be reduced by up to 34 to 47% from 9:00 AM to 6:00 PM at the most (Fig. 20).

[0150] The effect in the experiment in these buildings is that, although both films used in this experiment (Ref film and S-TIEP-400 film of the present invention) have the same near-infrared blocking rate (left NIR part of Fig. 21), the internal temperature in one summer is judged to be different due to the difference in emissivity (Emission part).

Claims

1. An absorption layer comprising a conjugated polymer; and A high-transmittance ultra-thin film comprising a reflective layer comprising inorganic nanoparticles.

2. In paragraph 1, The absorption layer and the reflection layer are high-transmittance ultra-thin films formed through phase separation-induced self-assembly of conjugated polymers and inorganic nanoparticles.

3. In paragraph 1, A high-transmittance ultra-thin film comprising one or more inorganic nanoparticles selected from the group consisting of silica, zinc oxide, titanium dioxide, silver, and gold.

4. In paragraph 1, A high-transmittance ultra-thin film having an absorption layer thickness of 100 to 500 nm.

5. In paragraph 1, A high-transmittance ultra-thin film having a reflective layer thickness of 1300 to 1800 nm.

6. In paragraph 1, A high-transmittance ultra-thin film having a transmittance of 80% or more for wavelengths of 400 to 750 nm.

7. In paragraph 1, A high-transmittance ultra-thin film with a reflectivity of 25% or more.

8. In paragraph 1, A high-transmittance ultra-thin film comprising at least one conjugated polymer selected from the group consisting of polythiophene, polyalkylthiophene, polyaniline, polyfluorene, polyparaphenylenevinylene, polyphenylene, polyparaphenylene, polydialkylfluorene, polyfluorenebenzothiadiazole and derivatives thereof.

9. In paragraph 1, High-transmittance ultra-thin film is a high-transmittance ultra-thin film for use as a building exterior material, a building exterior coating agent, an architectural glass coating agent, a glass coating agent, a film, a fiber coating agent, an exterior material for a vehicle, an exterior coating agent for a vehicle, an interior material for a vehicle, an interior coating agent for a vehicle, an agricultural material, or a mobile material.

10. A step of applying a certain amount of a solution containing a conjugated polymer and inorganic nanoparticles to a substrate; A step of forming an absorption layer and a reflection layer; and A method for manufacturing a high-transmittance ultra-thin film, comprising the step of curing a stabilized solution.

11. In paragraph 10, A method for producing a high-transmittance ultra-thin film, wherein the inorganic nanoparticles include one or more selected from the group consisting of silica, zinc oxide, titanium dioxide, silver, and gold.

12. In paragraph 10, A method for producing a high-transmittance ultra-thin film, wherein in the above-mentioned applying step, the solution comprises at least one conjugated polymer selected from the group consisting of polythiophene, polyalkylthiophene, polyaniline, polyfluorene, polyparaphenylenevinylene, polyphenylene, polyparaphenylene, polydialkylfluorene, polyfluorenebenzothiadiazole, and derivatives thereof.

13. In paragraph 10, A method for manufacturing a high-transmittance ultra-thin film, wherein the step of forming the above absorption layer and reflection layer includes a step of forming the absorption layer and reflection layer through phase separation-induced self-assembly of a conjugated polymer and colloidal silica.

14. In paragraph 10, A method for manufacturing a high-transmittance ultra-thin film, wherein the above-mentioned applying step is performed by bar coating, spin coating, or spray coating.

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