研磨處理對竹材表面性質及塗膜附著性之影響

Effect of Sanding Treatment on the Surface Properties and Adhesion of Coated Bamboo

本研究係探討表面研磨處理對竹材表面性質之影響，及對塗膜附著性之改善效益，進而歸納最佳的前處理方法，提供竹材加工業者參考，以提升竹材的塗裝品質，增加產品的經濟價值而提高收益。竹材採用5 年生孟宗竹及麻竹，研磨處理分成單一階段及兩階段處理，前者分別使用# 120、# 180、# 320 及# 400 砂布研磨，後者先經粗研磨後再細研磨，共分成# 120 → # 320、# 120 →# 400、# 180 → # 320 及#180 → # 400 等處理，塗料使用市售硝化纖維素拉卡（NC 拉卡）及水性聚胺酯（PU）塗料，表面性質測定項目包括粗糙度、濕潤性、顏色及SEM 觀察等，塗膜附著性分別採用方格試驗、180°剝離強度試驗及拉伸剪斷強度試驗等3種方法。試驗結果發現，以粗砂布研磨者竹材表面較粗糙，又兩階段研磨處理者其材面較未處理材平滑，但較單一階段研磨者粗糙。以水為滴液時，兩階段研磨處理者之濕潤性有較單一階段者為佳。不論經過單一階段或兩階段研磨處理均不會破壞竹材原本的綠色。整體而言，以兩階段研磨者具有較佳的塗膜附著性，又所有塗裝試片在附著性試驗時之破壞，均為塗膜與竹材表面的界面破壞。 The poor adhesion of films on bamboo was criticized by the bamboo industry. To develop a pretreatment method that improves the adhesion of film and that the bamboo industry becomes motivated to explore potential applications, and subsequently increase the economic value of bamboo products, a study of sanding treatments was examined. Five years-old moso bamboo [Phyllostachys pubescens (Carr.) A. and C. Riv.], and ma bamboo (Dendrocalamus latiflorus Munro), nitrocellulose lacquer and waterborne polyurethane coating were used in the study. Sanding treatments including single stage process i.e. #120, #180, #320, and #400 sanding cloth and two-stage process such as #120→#320, #120→#400, #180→ #320, and #180→#400 were applied respectively. Surface properties of bamboo such as roughness, wettability, color and SEM inspection were evaluated, and cross-cut method, 180° peel strength, and shear strength tests for measuring adhesion of coatings were used. The results of sanding treatment indicated that the using the coarser sanding cloth could get larger surface roughness, and surface of bamboo by two-stage process was smoother than that of untreated bamboo and coarser than that of by single stage process. The wettability of water on the bamboo by two-stage sanding process was better than that of using single stage process. All the sanding treatment could keep the green color of bamboo in this study. Two-stage process i.e. first rough sanding followed by fine sanding got the better adhesion of films on the bamboo. Interfacial failure between film and bamboo for all adhesion test specimens were also found in this study.

The poor adhesion of films on bamboo was criticized by the bamboo industry. To develop a pretreatment method that improves the adhesion of film and that the bamboo industry becomes motivated to explore potential applications, and subsequently increase the economic value of bamboo products, a study of sanding treatments was examined. Five years-old moso bamboo [Phyllostachys pubescens (Carr.) A. and C. Riv.], and ma bamboo (Dendrocalamus latiflorus Munro), nitrocellulose lacquer and waterborne polyurethane coating were used in the study. Sanding treatments including single stage process i.e. #120, #180, #320, and #400 sanding cloth and two-stage process such as #120→#320, #120→#400, #180→ #320, and #180→#400 were applied respectively. Surface properties of bamboo such as roughness, wettability, color and SEM inspection were evaluated, and cross-cut method, 180° peel strength, and shear strength tests for measuring adhesion of coatings were used. The results of sanding treatment indicated that the using the coarser sanding cloth could get larger surface roughness, and surface of bamboo by two-stage process was smoother than that of untreated bamboo and coarser than that of by single stage process. The wettability of water on the bamboo by two-stage sanding process was better than that of using single stage process. All the sanding treatment could keep the green color of bamboo in this study. Two-stage process i.e. first rough sanding followed by fine sanding got the better adhesion of films on the bamboo. Interfacial failure between film and bamboo for all adhesion test specimens were also found in this study.