The Research Of The Law Of Light-induced Discoloration Of Biomass Decoration Materials And Its Incentives

In this paper, the light-induced discoloration is investigated in basswood veneer, decorative paper (wood-veined paper and impregnated paper) and PVC sticker (dark and light color). We investigate the law of the change of color and the incentives of the producing of color, with spectrophotometer, fourier transform infrared spectroscopy and electron spin resonance spectroscopy. Furthermore, the ultraviolet spectrophotometer is also used to measure the transmission spectra of the typical paint films. In this work, we hope to provide basic and scientific theory to avoid damaging induced by light. The main results are shown as follow:1. The general characters of the light-induced discoloration are observed in basswood single board, decorative paper and PVC sticker when they are radiated by natural and ultraviolet light. After radiating, we observed basswood single board, decorative paper and PVC sticker by ultraviolet and find that the lightness index decrease, the red and green index change little, the yellow and blue index increase, and visual display become yellow. In addition, the color induced by the long-time ultraviolet radiation change more strongly. While the effect induced by natural light is smaller than induced by ultraviolet. The same light-induced discoloration phenomenon is observed in basswood single board, decorative paper and PVC sticker. The change of the chromatic difference is observed mainly in the early, and then become steady. In addition, the color induced by the long-time ultraviolet radiation change more strongly.2.After checking light irradiation by using FT-IR, the light-induced discoloration of basswood single board comes from lignin and oxidative degradation. As the increasing of light irradiation, oxidative degradation of high polymer and rupture of long molecular chain, produces oxygenic function comprised by hydroxyl group, ketone group and aldehyde group. In addition, the change shown above is drastic at the beginning of the reaction, and then turn to steady.3. After being light irradiated, the carbon oxygen free radical concentration of wooden materials can be observed in the obvious. At the beginning, the carbon oxygen free radical concentration increases rapidly and then after a period of steady, goes on increasing. All in all, as the increasing of light irradiation, free radical concentration increases. It has the same regular with color difference. The changes of free radical concentration are changing with color. Incentives maybe include the carbon oxygen free radical after wooden materials irradiating wooden materials.4. Under the influence of light irradiation, PVC sticker of dark color has a little change because of covering of printing pigment. The damaging by light of wood-veined paper and impregnated paper are not observed in this experiment. It is because that the most of titanium dioxide is brought to wood-veined paper and impregnated paper. The light-induced discoloration of impregnated paper results from discoloration of resin. Because the light selective absorption change induced by the chemical property change of materials and transmittance declines.