塗裝木材人工加速劣化與自然曝露試驗之相關性（Ⅰ）表面性質變化

Correlation of Accelerated Testing to Natural Exposure of Coated Wood (Ⅰ) Variations in the Surface Properties

張上鎮(Shang-Tzen Chang) ； 蕭雅芳(Yea-Fang Shiau)

《林產工業》 17卷1期 (1998/03) Pp. 123-137

摘要

為了瞭解塗裝木材之自然曝露試驗與人工加速劣化試驗的相關性，本研究之第一部分試驗先將杉木與硬槭木之素材與聚胺基甲酸酯透明塗裝材經由實際室內放置試驗與二種人工加速照光試驗後，分析其表面性質變化。試材經由室內長時間放置與二種人工加速照光試驗後，隨著試驗時間之增長，明度保留率下降，而色差值與黃色指數則明顯的增大，表面顏色變化都趨向紅黃色系，光澤度亦下降。在室內放置試驗中，塗裝材的變色較素材為輕微，顯示聚胺基甲酸醋塗料能抑制木材在室內之變色。至於塗膜之化學結構變化，經過人工加速耐光試驗後，芳香族聚胺基甲酸醋塗膜之化學結構產生明顯的變化，而脂肪族聚胺基甲酸酯塗膜之化學結構變化相當輕微；而在室內放置8個月後，二種塗膜表面之化學結構均未產生明顯的變化。

關鍵字

杉木 ； 硬槭木 ； 聚胺基甲酸酯塗料 ； 表面性質 ； 自然曝露試驗 ； 人工加速耐光試驗

並列摘要

To establish the correlation between the natural exposure and the accelerated lightfastness testing, the first part of this research is to examine the variations in surface properties of uncoated and coated China fir and hard maple after exposure to the indoors and to the accelerated lightfastness tester equipped with UVA-340 or UVA-351 sunlamps. The experimental results reveal that the brightness retention of specimens decreases, the color difference and the yellowness index increase as a function of exposure time. In fact, the color on the specimen surface changes to reddish yellow after exposure to the indoors or to the accelerated lightfastness tester. In addition, the gloss also decreases as a function of exposure time. During the indoor exposure, the color difference of specimens coated with polyurethanes is less than that of the uncoated specimens, indicating polyurethane provides a certain degree of protection against discoloration at the ambient conditions. Concerning with the changes of chemical structures of polyurethane, under the exposure to the accelerated lightfastness tester, significant changes were observed in the FTIR spectrum of aromatic polyurethane whereas very slight changes were observed in the FTIR spectrum of aliphatic polyurethane. On the other hand, the characteristics of absorption peaks in the FTIR spectrum of polyurethane remain the same even after exposure to the indoors for 8 months.

並列關鍵字

China fir ； hard maple ； polyurethane coating ； surface property ； natural exposure ； accelerated lightfastness testing