The Study On Fluorocarbon Resin Layer Coated On The PET Film

The polyethylene terephthalate (PET) film is widely used in packing materials and solar cells backplane materials due to its excellent processability, weather resisting property and good light transmittance. Fluorocarbon resin is applied in the field of long-lasting, heavy anti-corrosion for steel structure, marine anti-corrosion, decoration for external walls and solar cell backplane due to its outstanding performance regarding fine weather resisting property, chemical resistance property and self-cleaning property.In this paper, the composite coating films with the good properties of high transmittance and fine weather resisting property were successfully prepared by using PET film as the substrate depositing with the fluorocarbon resin on the surface of the PET film. At the meantime, the new methods of using silane coupler and liquidlike fluids were employed to modify SiO2. Then, the modified SiO2was filled into the fluorocarbon resin to prepare the composite coating of PET/modified SiO2FEVE with high transmittance, hydrophobicity and fine weather resisting property. The main results were displayed as follow:(1) The results of transmittance, water contact angle, tensile strength and elongation at break show the same trend that they increase firstly, and then decrease with the increasing fluorocarbon resin content. The optimal performances of the coating layer are achieved at the fluorocarbon resin content50wt%. Because at that content, the coating possesses well film forming property and can form a homogeneous and dense layer on the surface of PET film. The conventional evaluations on performances show that all the samples have the hardness of2H and the adhesion of1grade. The coated films perform good acid, alkali and water resistance. And after alkali corrosion, the coated films still show high transmittance.(2) The SiO2modified by KH550shows agglomeration in the fluorocarbon resin matrix, which leads to the decrease of the transmittance and tensile strength and elongation at break of the coated film. But the addition of modified SiO2forms a kind of micro-nano structure on the surface of the PET film and it improves the water contact angle largely. When the content of modified SiO2is0.5wt%, the water contact angle achieves the maximum of115°. The coated films prepared with different content of modified SiO2possess excellent acid, alkali and water resistance properties, and the hardness reaches2H and the adhesion reaches1grade. The SEM images show that the modified SiO2fall off the surface after alkali corrosion, but it does not affect the transmittance of the films much when the content of modified SiO2is very low.(3) Solvent-free SiO2nanofluids is prepared via ion exchange reaction process, and shows good chemical stability and monodispersity. The solvent-free SiO2nanofluids plays a role of enhancity the anti-reflective and hydrophobic properties of the composite coating layer. The transmittance, water contact angle, tensile strength and elongation at break increase due to the addition of solvent-free SiO2nanofluids. When the content of solvent-free SiO2nanofluids is0.2wt%, the water contact angle reaches101°. The hardness and adhesive force of the composite film made by adding different content of solvent-free SiO2nanofluids are still2H and1grade. The composite films also have excellent acid, alkali and water resistance properties. After alkali corrosion, only a few SiO2particles fall off the surface and the composite films remain high transmittance.