Radio electromagnetic wave high-transmission infrared low-emissivity material and preparation method thereof

Abstract

The invention relates to the technical field of functional new materials, in particular to a wireless electromagnetic wave high-transmission infrared low-emissivity material and a preparation method thereof. The infrared low-emissivity material with high wireless electromagnetic wave transmission has a reflection effect in 2-20 [mu] m wave band infrared rays, and has a direct transmission effect in a 100 kHz-1.6 THz communication electromagnetic wave band; the infrared low-emissivity material with high wireless electromagnetic wave transmission comprises a scatterer. The material has the advantages that the problems that an existing low-emissivity material has an electromagnetic shielding effect, application is limited and the like are solved, the preparation method is simple, and the material can be applied to radiation heat preservation and heat insulation in the fields of new energy automobiles, low-carbon energy-saving buildings, cold-chain logistics, low-carbon agriculture, smart cities and the like and infrared thermal camouflage compatible with a multiband stealth technology; good application prospects are realized.

Description

Technical Field

[0001] The invention relates to the technical field of functional new materials, and in particular to an infrared low-emissivity material with high transmittance to wireless electromagnetic waves and a preparation method thereof. Background Art

[0002] Infrared thermal radiation is an important carrier of energy and information transmission. Any object above absolute zero in nature will radiate energy in the form of electromagnetic waves. At room temperature and medium and high temperatures, the radiation spectrum of objects we come into contact with in daily life is mainly concentrated in the 2-20μm mid-infrared band. Infrared thermal radiation has a wide range of applications and great significance in the fields of infrared camouflage, thermal photovoltaic systems, night imaging, thermal regulation, etc.

[0003] Radiative temperature control is to change the radiation characteristics of objects in the environment by constructing the spectral characteristics of specific bands, thereby changing the temperature of the objects and achieving low-energy heat management. The construction industry currently accounts for about 40% of the world's primary energy use, of which more than 50% is used for heating, ventilation and air-conditioning systems. Existing temperature control designs are mainly based on heat conduction and heat convection to achieve temperature control, and rarely involve regulation of thermal radiation, but the heat consumed by the human body and buildings through thermal radiation accounts for about half of the total heat. Some designs are also based on thermal radiation for heat management, but the surface low-emissivity materials used in existing designs are all metals or metal oxides, which cannot take into account "infrared low-emissivity insulation and energy saving" and "effective transmission of communication information", making the existing infrared low-emissivity temperature control materials, The application is greatly limited. Especially in the context of the networking, intelligence, and digitization of new energy vehicles, low-carbon energy-saving buildings, cold chain logistics, and smart cities, and the upgrading of 5G and 6G communication technologies, it is difficult to play a role.

[0004] Infrared low-emissivity materials can not only be used for radiation temperature control, but also receive extensive attention in the field of thermal infrared camouflage. Thermal infrared camouflage mainly reduces the radiation energy or radiation temperature of the target object to hide the true temperature of the object, thereby preventing the object from being detected by infrared detection equipment. Commonly used infrared detection equipment operates in the 3-5μm and 8-14μm bands, and thermal infrared camouflage is mostly carried out for these two bands. One idea to achieve thermal infrared camouflage is to adjust the emissivity. When the temperature of the object remains unchanged, reducing the emissivity will reduce the thermal radiation energy of the object, reduce the possibility of the object being identified by the infrared detection device, and achieve infrared thermal camouflage. The infrared stealth technology of weapons and equipment requires a balanced and comprehensive design with other stealth technologies (radar stealth, etc.). However, metal or metal oxide low-emissivity materials have high reflectivity in the common working band of radar detection systems, 2-18GHz, and cannot take into account both infrared stealth and radar stealth.

[0005] Therefore, the realization of infrared thermal insulation materials with the characteristics of "wide-band infrared low emissivity" and "low electromagnetic signal attenuation" is of great significance to the deep integration of the core technologies of the dual-carbon strategy represented by low-carbon buildings and new energy vehicles with the next-generation information technology. It is also of great value to the compatibility of multi-band stealth technologies such as infrared thermal camouflage and radar millimeter-wave stealth. Summary of the invention

[0006] In order to solve the above problems, the present invention provides an infrared low emissivity material with high transmittance to wireless electromagnetic waves and a preparation method thereof.

[0007] The first purpose of the present invention is to provide an infrared low emissivity material with high transmittance to wireless electromagnetic waves, wherein the infrared low emissivity material with high transmittance to wireless electromagnetic waves has a reflective effect in the infrared band of 2 to 20 μm and a direct transmission effect in the communication electromagnetic band of 100 kHz to 1.6 THz; the infrared low emissivity material with high transmittance to wireless electromagnetic waves includes a scatterer.

[0008] Preferably, the infrared low emissivity material with high transmittance to radio electromagnetic waves has an average infrared reflectivity of at least 40% in the 2-20 μm band and a transmittance of at least 40% in the communication electromagnetic band of 100 kHz-1.6 THz.

[0009] Preferably, the scatterer is constructed by a non-metallic infrared low-emissivity material and air, or by at least two non-metallic infrared low-emissivity materials; the scatterer is in the shape of a regular or irregular cylinder, cone, sphere or strip.

[0010] Preferably, the scatterer is constructed by non-metallic infrared low emissivity material and air, and the construction method is: constructing air holes with an aperture of 0.2~50μm in the non-metallic infrared low emissivity material to form a scatterer, or constructing non-metallic infrared low emissivity particles with a size of 0.2-50μm in the air to form a scatterer.

[0011] Preferably, the scatterer is constructed by at least two non-metallic infrared low emissivity materials, and the construction method is: using two or more non-metallic infrared low emissivity materials with different refractive indices to prepare the scatterer, one of the non-metallic infrared low emissivity materials is a non-metallic infrared low emissivity particle with a particle size of 0.2~50μm.

[0012] Preferably, the non-metallic infrared low emissivity material is at least one of an infrared transparent crystal and an infrared transparent polymer; The infrared transparent crystal is at least one of sodium chloride, potassium chloride, potassium bromide, zinc sulfide, calcium fluoride, magnesium fluoride, cesium iodide, zinc selenide, zinc sulfide, diamond, sapphire, barium fluoride, cesium bromide, fused quartz, lithium fluoride, silver bromide, and silver chloride; The infrared transparent polymer is at least one of polyethylene, polyethylene and polystyrene copolymer, polypropylene, silicone rubber, butyl rubber, EPDM rubber, acrylic resin, alkyd resin, epoxy resin, polyurethane, polytetrafluoroethylene, hydrogenated styrene-butadiene block copolymer, ethylene-butylene triblock copolymer, polyolefin, and tyrosine tripeptide.

[0013] The second object of the present invention is to provide a method for preparing an infrared low emissivity material with high transmittance to radio electromagnetic waves, which specifically comprises the following steps: uniformly mixing a scatterer, an adhesive and a solvent to form a scatterer-adhesive-solvent dispersion; the mass ratio of the scatterer to the adhesive is: 50wt%-100wt% of the scatterer, and 0wt%-50wt% of the adhesive; the ratio of the mass of the solvent to the sum of the mass of the scatterer and the adhesive is 1-8:2; The scatterer-adhesive-solvent dispersion is evenly spread on the substrate with a thickness of 0.05~10mm; after curing, a film structure is formed, that is, an infrared low-emissivity material with high transmittance to radio electromagnetic waves.

[0014] Preferably, the solvent is any one of tetrahydrofuran, n-hexane, acetone, water, ethanol, dichloromethane, chloroform, or toluene; the adhesive is at least one of polyethylene, polyethylene and polystyrene copolymer, polypropylene, silicone rubber, butyl rubber, EPDM rubber, acrylic resin, alkyd resin, epoxy resin, polyurethane, polytetrafluoroethylene, hydrogenated styrene-butadiene block copolymer, ethylene-butylene triblock copolymer, polyolefin, and tyrosine tripeptide.

[0015] The third purpose of the present invention is to provide a method for preparing an infrared low emissivity material with high transmittance to wireless electromagnetic waves, which specifically includes the following steps: pressing the scatterer into a test cake; sintering the test cake at a high temperature and then cooling it to room temperature to obtain an infrared low emissivity material with high transmittance to wireless electromagnetic waves.

[0016] Preferably, the pressing pressure of the test cake is 1-20 MPa; the conditions for the high-temperature sintering are: a heating rate of 1-15°C / min, a sintering temperature of 200-2000°C, and a holding time of 30-180 min.

[0017] Compared with the prior art, the present invention can achieve the following beneficial effects: (1) The preparation process of the infrared low emissivity material with high transmittance to radio electromagnetic waves proposed by the present invention is simple and can be obtained by a simple process method; (2) The preparation method of the present invention can make the obtained infrared low-emissivity material with high transmittance to wireless electromagnetic waves have an average infrared reflectivity of >50% in the 2-20 μm band and a transmittance of >50% in the communication electromagnetic band of 100 kHz-1.6 THz, thus solving the problems of electromagnetic shielding effect and limited application of existing low-emissivity materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a particle size distribution diagram of micron sodium chloride crystal particles provided in Example 1 of the present invention; Figure 2 This is a macroscopic photograph of the large-scale preparation of the infrared low emissivity material with high radio electromagnetic wave transmittance provided in Example 1 of the present invention; Figure 3 1 is a reflectivity / transmittance spectrum of an infrared low emissivity material with high transmittance to wireless electromagnetic waves provided in Example 1 of the present invention; in the figure, A is a visible light reflectance spectrum, B is an infrared reflectivity spectrum, and C is a 300kHz-40GHz and 0.1THz-1.6THz electromagnetic wave transmittance spectrum; Figure 4 This is a temperature variation diagram of the thermal insulation performance test of the infrared low emissivity material with high wireless electromagnetic wave transmittance provided by Example 1 of the present invention; Figure 5 This is a diagram showing the results of a simulation experiment on a cold chain transport insulation box made of a material with high transmittance to wireless electromagnetic waves and low infrared emissivity provided in Example 1 of the present invention; Figure 6 It is a graph of the experimental results of 26GHz wireless video transmission using the infrared low emissivity material with high transmittance of wireless electromagnetic waves provided in Example 1 of the present invention; in the figure, A is a constellation diagram of the wireless signal at the receiving end when there is no obstacle between the transmitting antenna and the receiving antenna; B is a constellation diagram of the wireless signal at the receiving end when the thermal radiation material in Example 1 is placed between the transmitting antenna and the receiving antenna; C is a constellation diagram of the wireless signal at the receiving end when a commercial aluminum foil thermal insulation material is placed between the transmitting antenna and the receiving antenna; Figure 7 1 is a graph showing the results of a wireless charging experiment using a material with high transmittance of wireless electromagnetic waves and low infrared emissivity provided in Example 1 of the present invention; in the graph, A is a graph showing the charging condition when a mobile phone is directly placed on a wireless charger; B is a graph showing the charging condition when the thermal radiation material in Example 1 is placed between the mobile phone and the wireless charger; C is a graph showing the charging condition when a metal aluminum foil is placed between the mobile phone and the wireless charger; Figure 8 This is a result diagram of a terahertz imaging experiment using an infrared low-emissivity material with high radio electromagnetic wave transmittance according to Example 1 of the present invention; in the figure, A is a top view of the items in the bag, B is a terahertz imaging result diagram of the thermal insulation bag prepared in Example 1, and C is a terahertz imaging result diagram of a commercial aluminum foil thermal insulation bag; Fig. 9 is the infrared reflectivity spectrum of the infrared low emissivity material with high radio electromagnetic wave transmittance provided by Example 2 of the present invention; Fig.10is the infrared reflectivity spectrum of the infrared low emissivity material with high radio electromagnetic wave transmittance provided by Example 3 of the present invention; Fig.11 This is the infrared reflectivity spectrum of the infrared low emissivity material with high transmittance to wireless electromagnetic waves provided by Examples 4 and 5 of the present invention. DETAILED DESCRIPTION

[0019] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the following description, the same modules are represented by the same reference numerals. In the case of the same reference numerals, their names and functions are also the same. Therefore, the detailed description thereof will not be repeated.

[0020] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not constitute a limitation of the present invention.

[0021] The present invention provides an infrared low emissivity material with high transmittance to wireless electromagnetic waves, comprising a scatterer, wherein the infrared low emissivity material with high transmittance to wireless electromagnetic waves has a reflective effect in the 2-20 μm infrared band and a direct transmission effect in the 100 kHz-1.6 THz communication electromagnetic band; preferably, the infrared low emissivity material has a reflective effect in the 2-14 μm infrared band; The material has an average infrared reflectivity of at least 40% in the 2~20μm band and a transmittance of at least 40% in the communication electromagnetic band of 100kHz~1.6THz; The scatterer is constructed by non-metallic infrared low-emissivity material and air, or by at least two non-metallic infrared low-emissivity materials, and has low emissivity in the infrared band; the shape of the constructed scatterer can be regular or irregular, including cylinder, cone, sphere, strip, and irregular cylinder, cone, sphere, strip, etc.; When the scatterer is constructed by non-metallic infrared low emissivity material and air, the construction method is: constructing air holes with an aperture of 0.2-50 μm in the non-metallic infrared low emissivity material to form the scatterer, or constructing non-metallic infrared low emissivity particles with a size of 0.2-50 μm in the air to form the scatterer; When the scatterer is constructed by at least two non-metallic infrared low emissivity materials, the construction method is: preparing the scatterer by using two or more non-metallic infrared low emissivity materials with different refractive indices; one of the non-metallic infrared low emissivity materials is a non-metallic infrared low emissivity particle with a particle size of 0.2 to 50 μm; The non-metallic infrared low emissivity material is at least one of an infrared transparent crystal and an infrared transparent polymer; The infrared transparent crystal is at least one of sodium chloride, potassium chloride, potassium bromide, zinc sulfide, calcium fluoride, magnesium fluoride, cesium iodide, zinc selenide, zinc sulfide, diamond, sapphire, barium fluoride, cesium bromide, fused quartz, lithium fluoride, silver bromide, silver chloride and other non-metallic infrared transparent crystals; The infrared transparent polymer is at least one of polyethylene, polyethylene and polystyrene copolymer, polypropylene, silicone rubber, butyl rubber, EPDM rubber, acrylic resin, alkyd resin, epoxy resin, polyurethane, polytetrafluoroethylene, hydrogenated styrene-butadiene block copolymer, polyolefin, and tyrosine tripeptide.

[0022] A method for preparing an infrared low emissivity material with high radio electromagnetic wave transmittance comprises the following steps: uniformly mixing a scatterer, an adhesive and a solvent to form a scatterer-adhesive-solvent dispersion; uniformly coating the scatterer-adhesive-solvent dispersion on a substrate to a thickness of 1 to 5 mm; curing the coating to form a film structure, i.e., the infrared low emissivity material with high radio electromagnetic wave transmittance; in a specific embodiment, curing after being placed at room temperature (15 to 25° C.) for 10 to 20 hours; The mass ratio of the scatterer to the adhesive is: 80wt%-100wt% of the scatterer, 0wt%-20wt% of the adhesive; the ratio of the mass of the solvent to the sum of the masses of the scatterer and the adhesive is 1-3:1; the solvent is any one of tetrahydrofuran, n-hexane, acetone or toluene; the adhesive is any one of a tri-block copolymer material (composed of polystyrene and ethylene-butylene copolymer, abbreviated as SEBS), polyethylene (PE) and polytetrafluoroethylene (PTFE) infrared low-emissivity organic matter, dissolved in the solvent.

[0023] A method for preparing an infrared low emissivity material with high transmittance to radio electromagnetic waves, comprising the following steps: placing a scatterer into a mold and pressing it into a test cake; sintering the test cake at a high temperature and then cooling it to room temperature to obtain a thermal radiation material with high infrared reflection and high transmittance in the communication electromagnetic wave band, that is, an infrared low emissivity material with high transmittance to radio electromagnetic waves; Among them, the pressing pressure of the test cake is 1~20MPa; the conditions of the high-temperature sintering are: the heating rate is 1~15℃ / min, the sintering temperature is 200~2000℃, and the insulation time is 30~180min; preferably, the pressure during the pressing of the test cake is 4~20MPa; the conditions of high-temperature calcination are: the heating rate is 2~10℃ / min, the sintering temperature is 450~600℃, and the insulation time at high temperature is 90~150min.

[0024] Example 1 A method for preparing an infrared low-emissivity material with high transmittance to radio electromagnetic waves, comprising the following steps: uniformly mixing a scatterer, an adhesive and an organic solvent to form a scatterer-adhesive-organic solvent dispersion; specifically, after optimization, the scatterer is selected to be a sodium chloride crystal with a size of 0.5-20 microns, the adhesive is SEBS, and the ratio of the scatterer to the adhesive is: 95wt% sodium chloride crystals and 5wt% SEBS; the organic solvent is tetrahydrofuran, and the mass is 200% of the sum of the mass of the scatterer and the adhesive. First, dissolve SEBS in tetrahydrofuran, stir magnetically at room temperature for 12 hours until the mixture is uniform, add micron NaCl particles, and continue stirring for 2 hours until the mixture is uniform, to form a NaCl-SEBS-n-hexane dispersion; The scatterer-binder-organic solvent dispersion was applied to the substrate by scraping the NaCl-SEBS-tetrahydrofuran dispersion onto the PE with a scraper, and the coating thickness was 2 mm; after 12 hours at room temperature, the tetrahydrofuran was completely volatilized, and the sample was solidified to form a 850 μm thick porous structure thin film coating, i.e., an infrared low emissivity material with high transmittance to radio electromagnetic waves.

[0025] This embodiment demonstrates the use of dielectric scattering principles to prepare infrared low-emissivity materials with high radio electromagnetic wave transmittance. Through the characteristics of more than 90% infrared high reflection and more than 70% high transmittance in the radio electromagnetic band, this infrared low-emissivity material can save indoor heating energy consumption and reduce cold chain transportation refrigeration material consumables compared with commercial insulation materials. At the same time, it supports wireless video information transmission, wireless charging, cold chain logistics terahertz security inspection imaging and other radio electromagnetic wave application scenarios. Due to its excellent suppression of infrared thermal radiation and high transmittance characteristics of non-electromagnetic shielding communication, this infrared low-emissivity material is expected to replace the current traditional metal insulation materials with strong electromagnetic shielding effects, and meet the society's needs for "thermal comfort, thermal insulation and heat preservation" and "high communication quality, all things connected smart city".

[0026] A thermal insulation test device was built with a tin box and insulating polystyrene foam, the size of the tin box was 40cm×25cm×24cm. The infrared low emissivity material with high transmittance of radio electromagnetic waves and coated with PE as the substrate prepared in Example 1 was affixed to the inner and outer surfaces of the tin box, and a thermocouple was suspended and attached to the box to measure the temperature inside the box. The control group was a tin box with commercial white paint on the inner and outer surfaces, and a thermocouple was suspended and attached to the same position in the box to measure the temperature inside the box. The tin box was placed on the insulating foam, the device was placed on the outdoor ground, and the ambient temperature and ground temperature were recorded using thermocouples.

[0027] The above-mentioned iron box with heat radiation material coated inside and outside was used, and the control group was a white paint box and an iron box with commercial aluminum foil insulation material coated inside and outside to conduct a simulation experiment of cold chain transportation insulation box. In the hot outdoor conditions in summer, the same mass of ice cubes were placed in the heat radiation material box, the white paint box and the aluminum foil insulation box, and the melting speed of the ice cubes in the box was recorded.

[0028] A wireless communication system was built to conduct a wireless signal transmission experiment. The wireless communication system uses QPSK modulation technology to encode a video signal into a 26GHz wireless electromagnetic signal, which is transmitted from the transmitting antenna to the receiving antenna at a rate of 357Kbps. The following conditions were set between the transmitting antenna and the receiving antenna: no obstacles, infrared low-emissivity materials with high transmittance of wireless electromagnetic waves in Example 1, and commercial aluminum foil insulation materials. The constellation diagrams of the receiving end signals in the three cases were recorded to characterize the quality of wireless signal transmission.

[0029] A wireless charging experiment was conducted using a wireless charger. The frequency of the radio electromagnetic waves emitted by the wireless charger is 100-148.5kHz, and the mobile phone used supports a maximum wireless charging power of 27W. The following conditions were set between the wireless charger and the mobile phone: no obstacles, the heat radiation material in Example 1, and aluminum foil. The charging conditions of the mobile phone in the three conditions were recorded.

[0030] A terahertz imaging experiment was conducted using a terahertz security imaging system. The operating frequency of the terahertz security imaging system was 35 GHz. Example 1 was pasted inside a non-woven bag to prepare an insulation bag made of infrared low emissivity material with high radio electromagnetic wave transmittance. The control group was a commercial aluminum foil insulation bag. Fruits, canned cola, metal toy guns and other items were placed in the insulation bag of Example 1 and the control commercial aluminum foil insulation bag, and the terahertz security imaging system was used to perform security inspection imaging of the items in the insulation box.

[0031] like Figure 1 The figure shows a scanning electron microscope photograph of the micron sodium chloride crystal particles in Example 1 of the present invention, which shows that the size of the micron sodium chloride crystal particles is 0.5-20 μm.

[0032] like Figure 2 The macroscopic photograph shown is a large-scale preparation of the infrared low emissivity material with high transmittance to wireless electromagnetic waves in Example 1 of the present invention. The material has a white appearance and has good fluidity, universality, and easy processability.

[0033] like Figure 3As shown in A, the reflection spectrum of the infrared low emissivity material with high radio electromagnetic wave transmittance in Example 1 of the present invention in the sunlight band (0.2~2.5μm), the average solar reflectivity of the material reaches 97.9%; the reflection spectrum of the material in the mid-infrared band (2.5~20μm), the average infrared reflectivity of the material at 2.5-14μm reaches 85.2%. Figure 3 As shown in B, the transmittance of the material in the communication electromagnetic band (1~40GHz) reaches more than 80%. Sodium chloride and SEBS are both infrared low-emissivity materials, and have very low absorption of infrared radiation in the range of 2.5~20μm. Due to Mie scattering, the scatterer sodium chloride crystal particles with a size range of 0.5~20μm can strongly scatter sunlight and mid-infrared light, making the material have high reflectivity in the 0.2~20 micron band, reflecting solar radiation energy and near-infrared-mid-infrared radiation, meeting the optical requirements of radiation thermal insulation. At the same time, the material does not contain metals or metal oxides, and the dielectric material has high transmittance to electromagnetic waves in the communication band, meeting the electromagnetic requirements of various communication scenarios.

[0034] Figure 4 The temperature variation diagram of the thermal insulation performance test of the infrared low emissivity material with high transmittance of wireless electromagnetic waves in Example 1 of the present invention is shown. Under outdoor conditions, compared with the iron box coated with commercial white paint, the temperature inside the iron box coated with the thermal radiation material is lower during the daytime when the weather is clear and the temperature is high, and the temperature of the iron box coated with the thermal radiation material is lower at night when the temperature is low. During the day, the iron box coated with the thermal radiation material has a cooling effect on high-temperature environments and a heat preservation effect on low-temperature environments. It shows better stability to outdoor temperature changes and reduces the energy consumption of HVAC required to maintain a constant indoor temperature.

[0035] Figure 5 The results of the simulation experiment of the cold chain transportation insulation box made of infrared low emissivity material with high wireless electromagnetic wave transmission in Example 1 of the present invention are shown. Under hot outdoor conditions in summer, compared with commercial white paint boxes and commercial aluminum foil insulation boxes, the thermal radiation material in Example 1 can reduce the melting rate of ice cubes in the box. It shows that infrared low emissivity material with high wireless electromagnetic wave transmission can reduce the use of refrigeration material consumables in cold chain transportation scenarios.

[0036] Figure 6 The figure shows the experimental results of 26GHz wireless video transmission of the infrared low emissivity material with high radio electromagnetic wave transmittance in Example 1 of the present invention. When there is no obstacle between the transmitting antenna and the receiving antenna, the constellation diagram of the wireless signal at the receiving end is as follows: Figure 6 As shown in A, the points in the constellation diagram are scattered and stable, and the bit information transmitted by the transmitting end can be correctly demodulated, and the video is transmitted normally. When the thermal radiation material in Example 1 is placed between the transmitting antenna and the receiving antenna, the constellation diagram of the wireless signal at the receiving end is as follows Figure 6 As shown in B, the points in the constellation diagram are scattered and stable, and the bit information transmitted by the transmitter can be correctly demodulated, and the video is transmitted normally. When commercial aluminum foil insulation material is placed between the transmitting antenna and the receiving antenna, the constellation diagram of the wireless signal at the receiving end is as follows Figure 6 As shown in C, the constellation diagram is disordered, the bit information transmitted by the transmitter cannot be demodulated, and the video cannot be transmitted. The experimental results show that the infrared low emissivity material with high wireless electromagnetic wave transmittance in Example 1 of the present invention has excellent wireless electromagnetic wave transmittance and can achieve high-quality wireless communication.

[0037] Figure 7 1 is a graph showing the results of a wireless charging experiment using a wireless electromagnetic wave high transmittance infrared low emissivity material according to Example 1 of the present invention. When a mobile phone is placed directly on a wireless charger, Figure 7 As shown in A, it can be charged normally, and the mobile phone screen shows that the charging power is 27W; when the thermal radiation material in Example 1 is placed between the mobile phone and the wireless charger, as shown in Figure 7 As shown in B, wireless charging is still possible, and the power is 27W; when the metal aluminum foil is placed between the mobile phone and the wireless charger, Figure 7 The battery C in the middle cannot be charged.

[0038] Figure 8 This is a result diagram of a terahertz imaging experiment using an infrared low-emissivity material with high transmittance to radio electromagnetic waves according to Example 1 of the present invention. Figure 8 A in the middle is a top view of the fruit, canned cola, metal toy gun and other items placed in the bag. When using a terahertz imager to perform security inspection imaging on a commercial aluminum foil insulation bag, Figure 8 As shown in Figure C, due to the shielding effect of the aluminum foil, the items in the bag cannot be detected, so it is necessary to open the box for security inspection, resulting in temperature changes. Figure 8 As shown in B, the terahertz imaging of items such as fruits, canned cola, and metal toy guns in the bag is clear. When the thermal insulation bag is made of infrared low-emissivity materials with high transmittance of radio electromagnetic waves, it supports security imaging detection without unpacking, achieving thermal insulation throughout the cold chain warehousing, security inspection, and transportation process.

[0039] Example 2 A method for preparing an infrared low-emissivity material with high transmittance to radio electromagnetic waves comprises the following steps: uniformly mixing a scatterer, an adhesive and an organic solvent to form a scatterer-adhesive-organic solvent dispersion; specifically, the preferred scatterer is a micron sodium chloride crystal, the size of the micron sodium chloride crystal is 0.5-20 microns, and the adhesive is SEBS; the ratio of the scatterer to the adhesive is: 82wt% of the sodium chloride crystal and 18wt% of the SEBS. The organic solvent is n-hexane, and the mass is 300% of the sum of the mass of the scatterer and the adhesive. First, SEBS is dissolved in n-hexane, magnetically stirred at room temperature for 12 hours until the mixture is uniformly mixed, and micron NaCl particles are added, and stirring is continued for 2 hours until the mixture is uniformly mixed to form a NaCl-SEBS-n-hexane dispersion.

[0040] The NaCl-SEBS-n-hexane dispersion was scraped onto the PE substrate with a scraping thickness of 2 mm. After 12 hours at room temperature, the n-hexane was completely volatilized and the sample was solidified to form a coating with a thickness of 850 μm, which is an infrared low-emissivity material with high transmittance to radio electromagnetic waves.

[0041] like Fig. 9 As shown, the reflection spectrum of the thermal radiation coating with high infrared reflection and high transmission in the communication electromagnetic band in Example 2 of the present invention in the mid-infrared band (2.5-20μm).

[0042] Example 3 A method for preparing an infrared low emissivity material with high radio electromagnetic wave transmittance, comprising the following steps: placing a scatterer into a mold and pressing it into a test cake; sintering the test cake at a high temperature and then cooling it to room temperature to obtain an infrared low emissivity material with high radio electromagnetic wave transmittance; Specifically, the scatterer is a micron sodium chloride crystal, and the size of the micron sodium chloride crystal is 0.5 to 20 microns. First, the micron sodium chloride crystal powder is placed in a cylindrical mold with a diameter of 80 mm, and the micron sodium chloride crystal powder is pressed into a cylindrical test cake with a diameter of 8 mm under a pressure of 4 MPa; the test cake is placed in a tube furnace, and the temperature is increased from room temperature to 500°C at a heating rate of 10°C / min, and the high temperature of 500°C is maintained for 120 minutes, and then the heating is stopped and the temperature is naturally cooled to room temperature, and the test cake is taken out to obtain an infrared low-emissivity material with high transmittance of radio electromagnetic waves.

[0043] like Fig.10 As shown, the reflection spectrum of the infrared low emissivity material with high transmittance to wireless electromagnetic waves in Example 3 of the present invention in the mid-infrared band (2.5-20 μm) is that the average infrared reflectivity of the coating at 2.5-14 μm reaches 92.2%.

[0044] Example 4 A method for preparing an infrared low emissivity material with high radio electromagnetic wave transmittance, comprising the following steps: placing a scatterer into a mold and pressing it into a test cake; sintering the test cake at a high temperature and then cooling it to room temperature to obtain an infrared low emissivity material with high radio electromagnetic wave transmittance; Specifically, the scatterer is a micron sodium chloride crystal, the scatterer ratio is 100%, and the size of the micron sodium chloride crystal is 0.5 to 50 microns. First, the micron sodium chloride crystal powder is placed in a cylindrical mold with a diameter of 80 mm, and the micron sodium chloride crystal powder is pressed into a cylindrical test cake with a diameter of 8 mm under a pressure of 4 MPa; the test cake is placed in a tube furnace, and the temperature is increased from room temperature to 500°C at a heating rate of 10°C / min, and the high temperature of 500°C is maintained for 120 minutes, and then the heating is stopped and the temperature is naturally cooled to room temperature, and the test cake is taken out to obtain an infrared low-emissivity material with high transmittance of radio electromagnetic waves.

[0045] like Fig.11 As shown, the reflection spectrum of the infrared low emissivity material with high transmittance to wireless electromagnetic waves in Example 4 of the present invention in the mid-infrared band (2.5-20 μm).

[0046] Example 5 A method for preparing an infrared low emissivity material with high radio electromagnetic wave transmittance, comprising the following steps: placing a scatterer into a mold and pressing it into a test cake; sintering the test cake at a high temperature and then cooling it to room temperature to obtain an infrared low emissivity material with high radio electromagnetic wave transmittance; Specifically, the scatterer is a micron sodium chloride crystal, the preferred scatterer ratio is 100%, and the preferred size of the micron sodium chloride crystal is 0.2-5 μm. First, the micron sodium chloride crystal powder is placed in a cylindrical mold with a diameter of 80 mm, and the micron sodium chloride crystal powder is pressed into a cylindrical test cake with a diameter of 8 mm under a pressure of 4 MPa; the test cake is placed in a tube furnace, and the temperature is increased from room temperature to 500°C at a heating rate of 10°C / min, and the high temperature of 500°C is maintained for 120 minutes, and then the heating is stopped and the temperature is naturally cooled to room temperature, and the test cake is taken out to obtain an infrared low-emissivity material with high transmittance of radio electromagnetic waves.

[0047] like Fig.11 As shown, the reflection spectrum of the infrared low emissivity material with high transmittance to wireless electromagnetic waves in Example 5 of the present invention in the mid-infrared band (2.5-20 μm).

[0048] The material proposed by the present invention can be applied in the fields of radiation cooling, radiation heating and thermal radiation camouflage, and can be applied to radiation insulation and infrared thermal camouflage compatible with multi-band stealth technology in the fields of new energy vehicles, low-carbon energy-saving buildings, cold chain logistics, low-carbon agriculture, smart cities, etc., and has good application prospects. Specifically, through the principle of medium scattering, non-metallic infrared low-emissivity materials and air are used to construct scatterers, and infrared low-emissivity materials with high transmittance of radio electromagnetic waves are prepared, achieving the characteristics of "wide-band infrared low-emissivity and high reflectivity" and "low electromagnetic signal attenuation", overcoming the incompatibility of existing infrared low-emissivity materials in "infrared low emissivity" and "radio wave high transmittance", which is of great significance to the deep integration of the core technologies of the dual-carbon strategy represented by low-carbon buildings and new energy vehicles and the next generation of information technology, and has important value for achieving the compatibility of infrared thermal camouflage with multi-band stealth technologies such as radar millimeter wave stealth.

[0049] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the disclosure of the present invention can be performed in parallel, sequentially or in different orders, as long as the desired results of the technical solution disclosed in the present invention can be achieved, and this document does not limit this.

[0050] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A low-emissivity infrared material with high transmittance to radio electromagnetic waves, characterized in that: The infrared low emissivity material with high wireless electromagnetic wave transmittance has a reflective effect in the 2-20 μm infrared band and a direct transmission effect in the 100 kHz-1.6 THz communication electromagnetic band; the infrared low emissivity material with high wireless electromagnetic wave transmittance includes a scatterer.

2. The infrared low emissivity material with high radio electromagnetic wave transmittance according to claim 1, characterized in that: The infrared low emissivity material with high transmittance to wireless electromagnetic waves has an average infrared reflectivity of at least 40% in the 2-20 μm band and a transmittance of at least 40% in the communication electromagnetic band of 100 kHz-1.6 THz.

3. The infrared low emissivity material with high radio electromagnetic wave transmittance according to claim 1, characterized in that: The scatterer is constructed by non-metallic infrared low-emissivity material and air, or by at least two non-metallic infrared low-emissivity materials; the shape of the scatterer is a regular or irregular column, cone, sphere or strip.

4. The infrared low emissivity material with high radio electromagnetic wave transmittance according to claim 3, characterized in that: The scatterer is constructed by non-metallic infrared low emissivity material and air, and the construction method is: constructing air holes with an aperture of 0.2-50μm in the non-metallic infrared low emissivity material to form a scatterer, or constructing non-metallic infrared low emissivity particles with a size of 0.2-50μm in the air to form a scatterer.

5. The infrared low emissivity material with high transmittance to wireless electromagnetic waves according to claim 3, characterized in that: The scatterer is constructed by at least two non-metallic infrared low emissivity materials, and the construction method is: using two or more non-metallic infrared low emissivity materials with different refractive indices to prepare the scatterer, wherein at least one non-metallic infrared low emissivity material is a non-metallic infrared low emissivity particle with a particle size of 0.2~50μm.

6. The infrared low emissivity material with high radio electromagnetic wave transmittance according to any one of claims 1 to 5, characterized in that: The non-metallic infrared low emissivity material is at least one of an infrared transparent crystal and an infrared transparent polymer; The infrared transparent crystal is at least one of sodium chloride, potassium chloride, potassium bromide, zinc sulfide, calcium fluoride, magnesium fluoride, cesium iodide, zinc selenide, zinc sulfide, diamond, sapphire, barium fluoride, cesium bromide, fused quartz, lithium fluoride, silver bromide, and silver chloride; The infrared transparent polymer is at least one of polyethylene, polyethylene and polystyrene copolymer, polypropylene, silicone rubber, butyl rubber, EPDM rubber, acrylic resin, alkyd resin, epoxy resin, polyurethane, polytetrafluoroethylene, hydrogenated styrene-butadiene block copolymer, ethylene-butylene triblock copolymer, polyolefin, and tyrosine tripeptide.

7. A method for preparing a material with high transmittance of wireless electromagnetic waves and low infrared emissivity according to any one of claims 1 to 6, characterized in that: Specifically, the method comprises the following steps: uniformly mixing a scatterer, an adhesive and a solvent to form a scatterer-adhesive-solvent dispersion; the mass ratio of the scatterer to the adhesive is: 50wt%-100wt% of the scatterer, and 0wt%-50wt% of the adhesive; the ratio of the mass of the solvent to the sum of the mass of the scatterer and the adhesive is 1-8:2; The scatterer-adhesive-solvent dispersion is evenly spread on the substrate with a thickness of 0.05~10mm; after curing, a film structure is formed, that is, an infrared low-emissivity material with high transmittance to radio electromagnetic waves.

8. The method for preparing the infrared low emissivity material with high radio electromagnetic wave transmittance according to claim 7, characterized in that: The solvent is any one of tetrahydrofuran, n-hexane, acetone, water, ethanol, dichloromethane, chloroform, or toluene; the adhesive is at least one of polyethylene, polyethylene and polystyrene copolymer, polypropylene, silicone rubber, butyl rubber, EPDM rubber, acrylic resin, alkyd resin, epoxy resin, polyurethane, polytetrafluoroethylene, hydrogenated styrene-butadiene block copolymer, ethylene-butylene triblock copolymer, polyolefin, and tyrosine tripeptide.

9. The method for preparing a material with high transmittance of wireless electromagnetic waves and low infrared emissivity according to any one of claims 1 to 6, characterized in that: The method specifically comprises the following steps: pressing the scatterer into a test cake; sintering the test cake at a high temperature and then cooling it to room temperature to obtain an infrared low-emissivity material with high transmittance to radio electromagnetic waves.

10. The method for preparing the infrared low emissivity material with high radio electromagnetic wave transmittance according to claim 9, characterized in that: The pressing pressure of the test cake is 1-20 MPa; the conditions of the high-temperature sintering are: a heating rate of 1-15°C / min, a sintering temperature of 200-2000°C, and a heat preservation time of 30-180 min.

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