Of Sno <sub> 2 </ Sub> / Polymer Shield Preparation And Properties Of Uv Transparent Insulation Materials

The purpose of this study is to prepare a kind of heat insulating material that can shield ultraviolet, permeate visible light and reflect near infrared. SnO₂/polymer composite material was prepared by heterocoagulation between polyacrylate latices and SnO₂ nanoparticles. Firstly, SnO₂ nanoparticle was prepared by hydrothermal method as functional filler of the composite material and was surface modified by KH550. XRD spectrum showed that the prepared SnO₂ nanoparticle was tetragonal rutile type with mean grain size of 8.7 nm. The particle size distribution before modification was in the range from 10 nm to 300 nm and from 2.5μm to 6μm, however, it became much narrower and changed to the range from 8 nm to 60 nm after modification, i.e. the aggregation was weakened, according to TEM and DLS characterization. The isoelectric point of SnO₂ particles shifted from 3.6 to 9 after modification and this shift made the inorganic nanoparticles can heterocoagulate with soapless latices within the most stable pH value range (7-8) of the latices. Moreover, the surface of SnO₂ was grafted with a layer of KH550 molecules whose -NH₄⁺ had electrostatic attraction with-COO^- of latices, which may improve the compatibility of the organic and the inorganic moieties.Secondly, polyacrylate latices were prepared by soapless emulsion polymerization as the matrix resin of the composite material. The effects of water-soluble monomer type, amount and addition manner on the size distribution of latices were studied. It was found that the size distribution of latices by semicontinuous process was narrower than that by batch process according to laser granularmetric analysis. Increase of the amount of water-soluble monomer result in narrower latices size distribution when semicontinuous process was applied, but a further increase of water-soluble monomer had little effect upon the latices size distribution. The latices diameter of the best sample varied from 50 nm-200 nm.Lastly, the composite material was prepared by heterocoagulation method, and the effects of pH value of the continuous phase, mass percentage of the modified SnO₂ nanoparticle on the morphology of the composite particles and stability of the composite particles were studied. Moreover, the water-resistance, alkali-resistance, solvent-resistance, adhesion, hardness, heat insulating effect and optical properties in UV-Vis region of the composite films were tested. The prepared composite films showed good UV shielding effect in the wavelength from 200 nm to 350 nm, and the transmittance in the visible range declined from 90％to 65％approximately as the mass percentage of SnO₂ nanoparticles in the composite film increased from 0.4％to 4.0％according to UV-Vis spectrums. These composite films showed good heat insulating effect according to a self-made heat insulating effect evaluation instrument. Besides, these films have 0 class or 1 class adhesion, 2H or 3H pencil hardness and show good water-resistance, alkali-resistance and solvent-resistance.