## 1 Introduction  
Infrared low emissivity coatings can not only benefit infrared stealth militarily, but also reduce the harm of infrared light to the human body in daily life by virtue of its ability to reflect more and absorb less infrared light [1]. As a special functional coating, it is widely used in military investigation and other aspects [2]. [PERSON] et al. [3] fabricated a polydimethylsiloxane (PDMS)-modified polyurethane (PU)/Ag composite coating with super-hydrophobicity and low infrared emissivity via the glass rod scraping method. The results indicated that at the 10 \(\upmu\)m particle size of flaky Ag powder and a 50% concentration of Ag powder in the coating, the coating had a dense surface structure and the lowest infrared emissivity. [PERSON] et al. [4] fabricated a low infrared emissivity coating using graphene surface-modified flaky aluminum complex powders (rGO-FAI) as fillers. Compared with pure flaky aluminum, the Vis-NIR diffuse reflectance of the rGO-FAI complex powders was significantly decreased, which was good for the low gloss of the coating. In addition, the coating maintained low infrared emissivity. [PERSON] et al. [5] designed and simulated VO2/metal multilayers to obtain a large tunability of the thermal emissivity of the infrared (IR) filters in the typical mid wave IR window of many infrared cameras. The multilayer structure was optimized to realize a low emissivity filter at high temperatures, useful for military purposes. With strict national control of the environmental protection industry, waterborne coatings have been vigorously promoted [6; 7]. Among them, waterborne UV-curable coatings have gradually become the research hotspot of domestic and foreign scholars due to their advantages of easy adjustment of concentration, fast drying speed [8], harmless volatiles and wide application range [9]. However, at the same time, it also has the disadvantages of poor corrosion resistance [10] and high gloss [11], which is less propitious regarding compatibility with visible light, thus limiting its domain in infrared low-emission materials. Therefore, an effective solution for achieving compatibility between low infrared emissivity and visible light is the only way to expand the application field of waterborne UV coatings. Currently, most of the infrared low emissivity coatings are produced by giving the metal a strong infrared reflection ability, via a filler added into the coating [12]. For instance, [PERSON] et al. [13] prepared low infrared emissivity coatings with outstanding thermal stability utilizing silicone resin as a binder, flake Al powder as a pigment and a low-melting glass powder as a functional filler. The results investigated that the low emissivity coating displayed favorable thermal stability at a 1.5 Al/polysiloxane ratio and the coating infrared emissivity was about 0.25 at 600 \({}^{\circ}\)C, which can show a good application prospect. [PERSON] et al. [14] prepared a polydimethylsiloxane (PDMS)-modified polyurethane (PU)/Al composite paint coat with super-hydrophobicity and low infrared emissivity. Research suggested that the paint coat possessed the lowest infrared emissivity and gloss performances at an 80 \({}^{\circ}\)C curing temperature. [PERSON] et al. [15] made low infrared emissivity paint coats owning excellent heat resistance, choosing epoxy-siloxane and Al as the binder together with pigment. Detailed conclusions indicated that the cured composite paint coats still possess low emissivity, profitable heat ageing and anti-thermal shock after the stability test. From the above research, we see that the metal Al powder stands out among numerous metal fillers on account of its low-cost, accessibility and satisfactory manifestation. However, these studies are based on silicone resin, polydimethylsiloxane-modified polyurethane, and epoxy-siloxane, but less based on waterborne UV coatings. In a preliminary study [16], the influence of infrared emissivity, chromaticity distortion and corrosion resistance of Al/waterborne acrylic coatings were investigated.