鹼處理對麻竹表面性質與塗膜附著性之影響

Effects of Alkali Treatment on the Surface Properties of Ma Bamboo and Adhesion of Coated Films

本研究係探討不同濃度（0.5、1、3及5%）、不同時間（10、20、30及40min）、不同溫度（25、50、70及90°C）及不同鹼被（NaOH、Na2CO3、NaHCO3及KOH）之鹼處理對麻竹表面性質之影響與對塗膜附著性之改善效益。竹材為5年生之麻竹，塗料採用市售硝化纖維素拉卡（NC拉卡）與水性聚胺酯塗料（PU），表面性質測定項目包括接觸角、SEM觀察、FTIR分析及顏色等，塗膜附著性則以180°剝離強度與拉伸剪斷強度評定之。試驗結果發現，使用不同塗料系統則有各合適的鹼處理條件，在兼顧竹材原本之綠色下，以NC拉卡時，麻竹以濃度1%Na2CO3溶液，在溫度70°C下，處理20min下可得最佳的塗膜附著性；以水性PU塗裝時，則以1%NaOH溶液，在溫度70°C下，處理20min之塗膜附著性最優良；又塗膜冷熱循環耐久性均優良。 To develop a pretreatment method that improves the adhesion of coated films, a study of alkali treatments on a bamboo surface was examined. Five years-old ma bamboo (Dendrocalamus latiflorus Munro), two kinds of nitrocellulose lacquer and waterborne polyurethane coatings were used in the study. Alkali treated with various conditions including concentrations (0.5, 1, 3, and 5%), times (10, 20, 30, and 40 min), temperatures (25, 50, 70, and 90°C), and the kinds of alkali (NaOH, Na2CO3, NaHCO3, and KOH) were applied, respectively. Surface properties of bamboo such as contact angle, SEM inspection, FTIR analysis, and color were evaluated, and 180° peel strength, and shear strength tests for measuring adhesion of coated films were used. The results indicated that the conditions for the best adhesion of coated ma bamboo based on the coatings system used in the study. As a conclusion, for keeping a original green color of bamboo, the alkali treatment of 1% NazC03 solution at 70°C for 20 min, had the best adhesion of NC lacquer for ma bamboo. However, for the waterborne PU coating, the alkali solution using 1% NaOH and at the same conditions of temperature and time as those of the NC lacquer was the best one.

To develop a pretreatment method that improves the adhesion of coated films, a study of alkali treatments on a bamboo surface was examined. Five years-old ma bamboo (Dendrocalamus latiflorus Munro), two kinds of nitrocellulose lacquer and waterborne polyurethane coatings were used in the study. Alkali treated with various conditions including concentrations (0.5, 1, 3, and 5%), times (10, 20, 30, and 40 min), temperatures (25, 50, 70, and 90°C), and the kinds of alkali (NaOH, Na2CO3, NaHCO3, and KOH) were applied, respectively. Surface properties of bamboo such as contact angle, SEM inspection, FTIR analysis, and color were evaluated, and 180° peel strength, and shear strength tests for measuring adhesion of coated films were used. The results indicated that the conditions for the best adhesion of coated ma bamboo based on the coatings system used in the study. As a conclusion, for keeping a original green color of bamboo, the alkali treatment of 1% NazC03 solution at 70°C for 20 min, had the best adhesion of NC lacquer for ma bamboo. However, for the waterborne PU coating, the alkali solution using 1% NaOH and at the same conditions of temperature and time as those of the NC lacquer was the best one.