Study Of Nanometer Powder Aqueous Suspension And Application Of It In Exterior Coatings

The coating industry of our country has developed rapidly in recent years, but compared with advanced country of the world, the overall level of the coating products still have very great disparity. Because of a series of distinctive physical, chemical properties of nanometer materials, it is paid widely attention to its application field. Utilizing nanometer materials to modify traditional coatings is the shortcut that can rapidly improve the level of coatings of our country. Due to great surface area and enormous surface energy, nanometer particles agglomerate very easily in the course of dispersion. In this paper, dispersion technology of the nanometer particles in water was studied firstly, and highly dispersed and stabilized nanometer aqueous suspensions were obtained. By application of nanometer aqueous suspensions to traditional exterior coatings, nanometer composite exterior coatings were prepared. Then, the influence of pigment volume concentration, type and addition of nano-materials on the properties of the nano-composite exterior coatings was studied in detail. In this paper, the nano-materials aqueous suspensions were prepared, and by means of viscosity, sedimentation volume experiment, Zeta potential measurement and TEM the suspensions were expressed. The influence of type and content of dispersants on the stability of nano-materials aqueous suspensions were studied. Meanwhile, pH value, super shear instrument, ultrasonic dispersion and other measures were also discussed. The experimental results show :â‘ By super shear instruments with 5000r/min for 30min and ultrasonic dispersions for 20 min, 5wt% nano-TiO₂ aqueous suspensions which particle size are 50nm⁶0nm can be obtained when P-19 used as dispersant (2% of nano-TiO₂ in mass), pH 8～10.â‘¡By super shear instruments with 6000r/min for 30min and ultrasonic dispersions for 20 min, 5wt% nano-SiO₂ aqueous suspensions which particle size are about 100nm can be obtained when P-19 and OP-10 used as dispersants (2% and 1% of nano-SiO₂ in mass), pH 8～9. Nano-TiO₂, nano-SiO₂ and their amalgam aqueous suspensions were added into the acrylate latex paint and silicon acrylate latex exterior coatings by way of technological conditions and nano-composite exterior coatings were prepared. The influence of contents of nano-materials and PVC on nano-composite exterior coatings was studied. The result show: main performances of the nano-composite coatings are improved obviously by addition of nano-materials with 0.5% of the total amount of coatings when PVC is 40%. In generally, with addition of composite nanometer particles, the modification effect of nanometer composite exterior coating was much better and nano-SiO2 was better than nano-TiO2. And silicon acrylate latex coatings were better than acrylate latex coatings. The contrast ratio was 0.98, pencil hardness raised 2H, the time of scrubbing resistance was 64714, water resistance was 2400h, acidity resistance was 720h.