Investigation On Weather Resistance Of The Polyester Polyurethane Films Modified By Composite Additives

In this paper, inorganic ultraviolet absorber, organic UV absorber （UV-531: UV-327=1:1）, antioxidant1010and hindered amine light stabilizers UV-622were used as additivesto modify thermoplastic polyester polyurethane. The UV aging resistance, the ozone agingresistance, and the UV ozone comprehensive aging resistance of the polyurethane filmsmodified by separate additive and by composite additives were tested by theself-developed UV aging, ozone aging, and UV ozone comprehensive aging integrationequipments. According to the analysis of the color difference, yellow index, UV-Vistransmission, and infrared spectrum during ozone, UV and ozone UV aging test, theinfluence of the single additive and the compound additives on the UV aging resistance,the ozone aging resistance, and the ultraviolet ozone comprehensive aging resistance ofthe polyurethane films were investigated.The optimization of the composition of the composite additives shows that both thecomplex inorganic UV absorbers consisting of nano-ZnO and nano-CeO₂by thecomposite ratio of3:2, and the composite organic UV absorbers consisting of UV-531andUV-327by the composite ratio of1:1make the coverage range of the absorptionwavelength of the film to ultraviolet light widest. The UV absorption range of thecomposite inorganic ultraviolet absorber reaches295-365nm, while the UV absorptionrange of the composite organic ultraviolet absorber reaches290-380nm, both of them canmake the doses of the ultraviolet rays through the film at each band similar.The anti-yellowing properties of the modified polyurethane under the UV aging andthe UV ozone aging conditions, were improved by separate addition of inorganic nano UVabsorbers, organic UV absorbers and antioxidants. However, separate addition of the fourkinds of additives has no significant effect on the anti-yellowing properties ofpolyurethane films under ozone aging condition. The accumulation rate of-NH/NH₂,-OHand-C=O produced by the photo-oxidation of polyurethane under UV aging and ozoneaging conditions are not effectively slowed down by addition of four kinds of additives.Separate addition of four kinds of additives can retard the accumulation rate of-NH/NH₂,-OH and-C=O in polyurethane under UV ozone aging condition, especially after long aging time. During ozone and UV aging test, the distinct synergistic aging effect wasdetected when the color difference, yellow index, and the photo oxidation index was usedas weather evaluated criterion, respectively.The results of weathering resistance of the polyester polyurethane film modified bycomposite additives show that, compared with a single additive, composite use ofantioxidant-1010and hindered amine-622with ultraviolet absorbers, respectively, cansignificantly improve the anti-yellowing properties and anti-aging properties of thepolyester polyurethane film during the process of UV aging and ozone aging, it can moresignificantly reduce the PI index and CI index of the polyester polyurethane film exposedto the ozone and UV environment.