| Summary: | 碩士 === 國立中興大學 === 森林學系 === 93 === The objective of this study is to analyze the improvement of homogeneity, dimensional stability and finishing performance of domestic medium and small diameter trees by polyurethane（PU） resins treatments. PU resins were prepared from combined castor oil modified alkyd resins, which were made from various oil content, different polyhydric alcohol （glycerin and pentaerythritol）and polybasic acid （phthalic anhydride and isophthalic acid）with aromatic polyisocyanates（PTDI and PMDI） or aliphatic polyisocyanates（PIPDI and PHDI）, respectively, by the molar ratio of NCO/OH+COOH of 1.2. Three kinds of wood, about a diameter 10~15 cm, such us China fir, Japanese cedar, and Taiwanina were supplied by Hui-Sun Forest station were used. The results indicated that the oil modified alkyds must be synthesized by adding polybasic acid in twice to avoid the alkyd resin gelled. The surface hardness, homogeneity, moisture excluding efficiency（MEE）and antiswelling efficiency（ASE） of wood were enhanced by PU resins treatments, especially for the Ⅳ-PMDI treatment, had the highest one. The Ⅳ-PMDI were prepared from combined PMDI with short-oil modified alkyd resin, which were made from pentaerythritol and isophthalic acid. The brightness and hue of wood decreased, while the chroma increased by PU treatments, i.e., a vivid and massive feeling of PU treated wood will be appealing to most people. To investigate finishing performance of wood, two kinds of finishing procedure i.e. NC lacquer sanding sealer → top clear and top clear only on PU treated wood were examined. The finishing performance of PU resins treated wood such as hardness, adhesion, light fastness and durability of films were enhanced, especially for top clear only on PU treated wood.
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