聚胺基甲酸酯之合成及其在木材塗裝與膠合上之應用──（II）聚胺甲酸酯樹脂之膠化性質

Studies on the Synthesis of Polyurethane and its Utilization as Adhesives and Coatings for Wood

聚羥基化合物與異氰酸鹽化合物混合而成聚胺基甲酸酯，可進行架橋反應而形成三次元網狀結構並高分子化而達硬化之目的。由不同種類異氰酸鹽化合物與聚羥基化合物之選用即可改變聚胺基甲酸酯膠合劑之膠合性及其所形成膠膜之特性，本試驗先合成各種不同構造及性質之反應性聚酯，並使其分子末端含有可反應之羥基，再與市售之異氰酸鹽化合物調配而做為二液型聚胺基甲酸酯樹脂並探討其膠化特性，由結果得知，聚酯合成時，酸與醇之種類及mole比不僅影響合成時之反應速率，同時亦影響合成聚酯之性質，其羥價實測值常低於理論值。聚胺基甲酸酯硬化所需之膠化時間及膠化反應速率除與硬化反應溫度有關外，異氰酸鹽、聚酯之種類及兩者之混合mole比均會產生影響。聚酯-Desmodur L系之膠化反應速率較聚酯-Desmodur N系者快，所需膠化時間較短。聚酯-Desmodur L系之NCO/（OH+COOH）mole比由1.0增加至1.5時，其反應速率減緩，膠化時間約延長一倍。在相同之NCO/（OH+COOH）mole比時，聚酯之羥價大者或末端羥基之反應性較高者，膠化反應速率較快。 Polyurethane resins are the blends of isoeyanate with polyol component. When the both components mixed together, they could undergo cross-link reac1ion and forming the three dimensional structure and their molecular weight would be increased and then cured. The kinds of isocyanate and polyol and their molar ratios were related to their adhesion properties. In this study, various kinds of polyesters with different molecular structures or properties were synthesized and then blended with isocyanates. The gelation properties of these various polyurethanes were tested. The results were summarized as follows. During the synthesis or polyester, the kind of acid and alcohol used and their molar ratios influenced not only the rate of reaction but al so the properties of their final products. The hydroxyl numbers measured were considerably less than theoretical values. The gel reaction rate and gelation time needed for polyurethane depended mainly on the temperature as curing. Besides, the kinds of polyisocyanate and polyester and their molar ratios showed influence too. Polyurethane blended with polyester and the isocyanate of Desmodur L had faster gel reaction rate than that of Desmodur N, and shorter gelation time was needed for the former. When the polyurethane blended with polyester and Desmodur N, as the molar ratio of NCO/(OH+COOH) increased from 1 to 1.5, which gel reaction rate slow down, and the gelation time increased almost twice. As the same molar ratio of NCO/(OH+COOH) was used, polyester with higher hydroxyl number or more reactivity hydroxyl end group had the faster gel reaction rate.

Polyurethane resins are the blends of isoeyanate with polyol component. When the both components mixed together, they could undergo cross-link reac1ion and forming the three dimensional structure and their molecular weight would be increased and then cured. The kinds of isocyanate and polyol and their molar ratios were related to their adhesion properties. In this study, various kinds of polyesters with different molecular structures or properties were synthesized and then blended with isocyanates. The gelation properties of these various polyurethanes were tested. The results were summarized as follows. During the synthesis or polyester, the kind of acid and alcohol used and their molar ratios influenced not only the rate of reaction but al so the properties of their final products. The hydroxyl numbers measured were considerably less than theoretical values. The gel reaction rate and gelation time needed for polyurethane depended mainly on the temperature as curing. Besides, the kinds of polyisocyanate and polyester and their molar ratios showed influence too. Polyurethane blended with polyester and the isocyanate of Desmodur L had faster gel reaction rate than that of Desmodur N, and shorter gelation time was needed for the former. When the polyurethane blended with polyester and Desmodur N, as the molar ratio of NCO/(OH+COOH) increased from 1 to 1.5, which gel reaction rate slow down, and the gelation time increased almost twice. As the same molar ratio of NCO/(OH+COOH) was used, polyester with higher hydroxyl number or more reactivity hydroxyl end group had the faster gel reaction rate.