Fabrication Of Solar-reflective Thermal Insulating Coating And Its Application In Surface Coated Paper

Solar-reflective thermal insulating coating is a new type of functional energy saving and environmentally friendly inorganic coating.It exhibits excellent comprehensive properties and can effectively reflect,insulate and radiate the heat produced by sunlight.Heat is not allowed to accumulate on the surface of the object body to achieve the purpose of reducing the body's internal temperature.At the same time,it can effectively reduce the energy consumption of air conditioning,sprinkler and electric fan in high temperature working conditions,saving a lot of resources.Therefore,solar-reflective thermal insulating coating has become an important research direction of green environmental protection and low carbon energy-saving.It is of great strategic significance to the research of solar-reflective thermal insulating coating,which is in accordance with the concept of sustainable development.Solar-reflective thermal insulating coating has a wide range of applications,but the feasibility and possibility of surface application of solar-reflective thermal insulating coating to cellulosic paper have not been explored.Therefore,this work aims to prepare solar-reflective thermal insulating coating with high reflective and thermal insulation effects,which was subsequently used in the surface application to cellulosic paper.Effect of feeding level of nano-TiO₂ and hollow glass microspheres on rheological behavior of the coatings,as well as heat-reflective properties,water repellency,air permeability and mechanical properties of the surface-coated paper was systematically studied.Results showed that the addition of nano-TiO₂ can induce the viscosity and dynamic viscoelasticity of coatings,while the addition of hollow glass microspheres of 0-4%can effectively reduce the rheological properties of coating system.It can be seen that the solar-reflective thermal insulating coatings,obtained from different formulations,has higher reflectivity to ultraviolet and visible light in the range of 200-900 nm of wavelength,with the highest reflectivity of 95%.Moreover,the addition of nano-TiO₂ and hollow glass microspheres can improve the reflectivity of the coatings.Furthermore,the increased nano-TiO₂ amount appeared to induce the improved hemispheric emittance of coated paper.Specifically,the hemispherical emittance of coated paper with 3%addition increased by 12.5%,compared with coated paper in the absence of nano-TiO₂.The hemispheric emittance of coated paper can also be improved by adding hollow glass microspheres,but the hemispheric emittance of coated paper will decrease when the addition amount is more than 6%.In addition,it was confirmed that the nano-TiO₂ addition played an important role in improving the water repellency,barrier performance,and mechanical properties of coated paper.Through SEM images we can clearly observed that there are a lot of pores and gullies on the surface of the base paper,while the coated paper is smooth and the fiber of the base paper is completely covered.