生漆精製時間對其乾燥性質之影響

EFFECT OF REFINING TIME TO THE CURING PROPERTIES OF ORIENTAL LACQUER

李綉玲(Hsiu-Ling Lee) ； 張家偉(Chia-Wei Chang) ； 盧崑宗(Kun-Tsung Lu)

《中華林學季刊》 49卷1期 (2016/03) Pp. 13-22

摘要

生漆(Oriental lacquer)是由割取漆樹屬漆樹樹幹，收集流出的汁液再精製而成的天然高分子塗料。本研究分析生漆之組成分，其中漆酚(Urushiol)佔54.1%，水為34.3%，樹膠質佔7.2%、含氮物質佔4.4%，外觀為乳黃色。為縮短生漆乾燥時間，將生漆以加熱攪拌方式進行精製，並以科學化方法評估生漆精製過程中不同含水率對於精製漆之黏度、外觀、分子量及塗膜性質之影響。在精製過程初期，其黏度隨含水率降低而減少，但當精製漆含水率達12%後，黏度則隨含水率下降而大幅上升，且顏色轉為透明深褐色，同時生漆中的漆酚單體因漆酶催化反應聚合為寡聚體及聚合體。精製漆之塗膜光澤度同時受到表面粗糙度與水球直徑影響，當含水率低於16.4%時，塗膜光澤度則隨粗糙度上升而下降﹔而當含水率高於16.4%時，塗膜光澤度因漆膜表面水球蒸發所留下之孔洞而降低，其中以含水率 16.4%之精製漆具有最佳塗膜光澤度。精製漆之塗膜硬化乾燥時間先隨含水率降低而延長，當精製漆之含水率為18.4%時具有最長硬化乾燥時間為13.0 hr，之後則隨含水率下降而縮短，以含水率3.5%之精製漆硬化乾燥時間最短僅6.0 hr。

關鍵字

生漆 ； 精製漆 ； 精製時間 ； 乾燥時間

並列摘要

Oriental lacquer, a natural polymeric coating, is refined from the sap which is collected from Rhus succedanea. In this study, the main components of the oriental lacquer with creamy yellow appearance were urushiol (54.1), water (34.3%), plant gum (7.2%), and nitrogenous compound (4.4%). Oriental lacquer was refined by heating and stirring for shortening the curing time of refined lacquer. The effects of water content on the viscosity appearance, molecular weight, and film properties of refined lacquers were evaluated by scientific methods. At an early refining process the viscosity of refined lacquer decreased with reducing of water content, while the reversed results were obtained at water content of 12% i.e. the viscosity of refined lacquer increased with reducing of water content. In the refining process, the cream yellow appearance of oriental lacquer transformed was transparent into brown color, and the urushiol monomers were polymerized to oligomers and polymers by laccase catalyzed oxidative polymerization. The gloss of refined lacquer films were affected by both of the surface roughness and water drop diameter. When the water content of refined lacquer below 16.4%, the films gloss decreased with increasing of surface roughness, while the films gloss decreased with increasing of water drop diameter at water content of over 16.4%. The refined lacquer with water content of 16.4% had the best gloss of films. The curing time of refined lacquer films were first extended with decreasing of water content, however it were shortened with further decreasing of water content. The refined lacquer with water content of 18.4% had the longest curing time of 13.0 hr. The refined lacquer with water content of 3.5% had the shortest curing time of 6.0 hr.

並列關鍵字

Oriental lacquer ； Refined lacquer ； Refining time ； Curing time