Effect of polyol on thermo-oxidative degradation of isocyanate resin for wood adhesives |
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Authors: | Kenji Umemura and Shuichi Kawai |
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Institution: | (1) Forestry and Forest Products Research Institute, Tsukuba Norin Kenkyu Danchi-nai, PO Box 16, 305-8687 Ibaraki, Japan;(2) Wood Research Institute, Kyoto University, Gokasho. Uji, 611-0011 Kyoto, Japan |
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Abstract: | The thermo-oxidative degradation of various polyol-added isocyanate resins for wood adhesives was studied using differential scanning calorimetry and thermogravimetry. The degradation of the resin cured with water began at 150°C. When a certain polyol was added to the resin at an NCO/OH ratio of 25 in addition to water, the cured resin began to degrade at 200°C. To clarify the cause of the good thermal stability in polyol-added resins, the effect of various polyols on the reactivity of isocyanate was investigated. It was found that the reactivity of isocyanate was enhanced by the addition of a dipropylene glycol and glycerin-type polyols. In addition, the effect of the NCO/ polyol-OH ratio was investigated using dipropylene glycoltype polyol. The reactivity of isocyanate increased with increasing polyol content. The thermal stability of the resin was improved to a certain degree by addition of a small amount of the polyol but deteriorated when a large amount of the polyol was added.Part of this paper was presented at the 48th annual meeting of the Japan Wood Research Society, Shizuoka, April 1998 |
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Keywords: | Isocyanate adhesives Thermo-oxidative degradation Differential scanning calorimetry Thermogravimetry Wood adhesives |
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