蓖麻油變性醇酸樹脂之油長與聚異氰酸酯種類樹脂性對PU質之影響

Effects of Oil Length of Alkyd Resins and Polyisocyanates on the Properties of Polyurethane Resins

本研究係探討蓖麻油變性醇酸樹脂之合成與性質，並以其為主劑，而以聚異氰酸酯為硬化劑，組成聚胺基甲酸酯（PU），分析不同主劑與硬化劑對PU物性之影響。醇酸樹脂係由蓖麻油、鄰苯二甲酸酐及丙三醇等依不同油長之短、中及長油性比例，以酯交換法合成。聚異氰酸酯分別採用芳香族（PTDI, PMDI）與脂肪族（PIPDI, PHDI）等四種。PU樹脂則依NCO／（OH+COOH）=1.2莫耳比調配而成。試驗結果得知，合成蓖麻油變性醇酸樹脂時，多元酸（鄰苯二甲酸酐）需採用分二段加入方式，以避免反應過快而使樹脂膠化，合成反應約在2.6h內即可完成；又樹脂之反應率、平均聚合度、重量平均分子量及黏度均以短油型醇酸樹脂者為最高。不同油長醇酸樹脂為主劑之PU樹脂中，以短油性者（S-PTDI）具最高之塗膜拉伸強度，蓖麻油者（C-PTDI）則最具有韌性，而塗膜耐熱性則以中油性者（M-PTDI）為最佳。不同聚異氰酸酯為硬化劑之PU樹脂中，以芳香族二苯基甲烷二異氰酸酯之衍生物（PMDI）調配者（S-PMDI）具最高之塗膜拉伸強度，而以脂肪族六亞甲基二異氰酸酯之三量體（PHDI）調配者（S-PHDI）則具最大塗膜破壞伸長率及最佳的塗膜耐熱性。 The objective of this study is to investigate the effect of the various oil length of castor oilmodifiedalkyd resins as polyol and polyisocyanates as hardener on the physical properties ofpolyurethane resins (PU). The properties of three grades of alkyd resins means short, medium, and long oil length alkyd resins based on castor oil, phthalic anhydride, and glycerol, employing transesterificationmethod were also examined. Four kinds of polyisocyanates such as aromatic hardeners (PTDI and PMDI)and aliphatic hardeners (PIPDI and PHDI) were used. The PU resins were prepared from combined polyolwith hardener by the molar ratio of NCO/OH+COOH of 1.2. The results indicated that the synthesis ofcastor oil-modified alkyd resins must be done by adding phthalic anhydride in twice to avoid the alkydresins gelled and the reaction had finished within 2.6 h. Among the alkyd resins, the short-oil one had thehighest extent of reaction, average degree of polymerization, weight molecular weight, and viscosity. Theshort-oil based PU resin (S-PTDI) had the highest tensile strength and the castor based one (C-PTDI) hadthe best toughness of film, while, the medium-oil based PU resin had the highest thermal stability. Amongthe PU resins containing different polyisocyanates, the aromatic hardener derived from 4,4′-diphenymethane diisocyanate (PMDI) based one (S-PMDI) had the highest tensile strength and the PHDI,which derived from hexamethylene diisocyanate, based PU resin (S-PHDI) had the best elongation atbreak and thermal stability.

The objective of this study is to investigate the effect of the various oil length of castor oilmodifiedalkyd resins as polyol and polyisocyanates as hardener on the physical properties ofpolyurethane resins (PU). The properties of three grades of alkyd resins means short, medium, and long oil length alkyd resins based on castor oil, phthalic anhydride, and glycerol, employing transesterificationmethod were also examined. Four kinds of polyisocyanates such as aromatic hardeners (PTDI and PMDI)and aliphatic hardeners (PIPDI and PHDI) were used. The PU resins were prepared from combined polyolwith hardener by the molar ratio of NCO/OH+COOH of 1.2. The results indicated that the synthesis ofcastor oil-modified alkyd resins must be done by adding phthalic anhydride in twice to avoid the alkydresins gelled and the reaction had finished within 2.6 h. Among the alkyd resins, the short-oil one had thehighest extent of reaction, average degree of polymerization, weight molecular weight, and viscosity. Theshort-oil based PU resin (S-PTDI) had the highest tensile strength and the castor based one (C-PTDI) hadthe best toughness of film, while, the medium-oil based PU resin had the highest thermal stability. Amongthe PU resins containing different polyisocyanates, the aromatic hardener derived from 4,4′-diphenymethane diisocyanate (PMDI) based one (S-PMDI) had the highest tensile strength and the PHDI,which derived from hexamethylene diisocyanate, based PU resin (S-PHDI) had the best elongation atbreak and thermal stability.