Preparation And Properties Of Anti-aging Exterior Wall Latex Coatings

The anti-aging exterior wall latex coatings with high performance were prepared in this Paper. The influence of these factors, including polymerizing technologies, reaction conditions and emulsifier formula and amount on polymerization and emulsion properties are discussed on the base of polyacrylate emulsion, namely three-unit system composed by butyl acrylate, methyl methacrylate and methacrylic acid. The experiment results show that pre-emulsification semi-continuous seed emulsion polymerization possesses higher monomer conversion and better performance than the other two polymerizing technologies as batch emulsion copolymerization and semi-continuous emulsion polymerization. By this method, the monomer conversion reaches up to 97.09%, and there are small particle size and narrow diameter distribution. The films have better performance of water resistance and stain resistance. The best pre-emulsification conditions optimized by orthogonal test are as follows: emulsifier dosage for 3%, monomer dropping time for 50 min, pre-emulsification temperature for 45℃and stirring speed for 500r/min. Acrylamide and (3 - ( methacryloxy ) propyl ) trimethoxysilane are involved in acrylic system to improve the properties of water resistance, stain resistance and anti-ultraviolet weather durability. The macromolecule couldn't degradation easily so as to improve the anti-ultraviolet and high-temperature resistance properties by acrylamide crosslinking modification. Silylated polymer resin coatings show perfect superiority in anti-ultraviolet weather durability. The interpentrating network structures formed by silicone monomer and polyacrylate emulsion enhance hardness and water resistance of films. And there silicone monomer can resist dirt pickups successfully. Furthermore, nano-rutile TiO2, antioxidant 1010 and two typical organic ultraviolet absorbers 2 - hydroxy - 4 - n - octyloxybenzophenone (UV-531) and 2 - (3 - tert - butyl - 2 - hydroxy - 5 - methylphenyl) - 5 - chloro - 2H - benzotriazole (UV-326) are used to temary mixing. Organic-inorganic hybrids R-TiO2/UV-531 and R-TiO2/UV-326 expand the range of UV absorption and have better performance of UV absorption with synergistic effects than organic/inorganic only as well as show well photostability in the air. The ultraviolet absorptivity of R-TiO2/UV-531 is up to 99.75%. The presence of nano-rutile TiO2 with excellent UV-blocking power that can probably slow down the decomposition of organic absorbers, and bring the properties of organic and inorganic ultraviolet absorbers into full play. Films modified by hybrids ultraviolet absorbers exhibit well hardness, strong adhesion, low chalking and excellent anti-aging properties. Finally, the recipes for preparing coatings are optimized by orthogonal test and correlation properties are examined according to national standard of architecture paints. The results show that the properties of the exterior latex coatings exceed national standards, especially the anti-aging properties. The anti-aging coatings manifest broad applied prospect.