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Abstract
A nonconventional curing system was developed using a simple mixing of urea-formaldehyde (UF) resins with polyfunctional hydrazide compounds under neutral contition. Several kinds of low molecular-weight dihydrazide compounds were investigated as hardners of the UF resins. Results were as follows: 1) As the minimum gelation times were observed in the range of molar ratios [dihydrazide/(free F+methylol F)] from 0.1 to 0.2, it was concluded that the hydrazide group has two or three functions with formaldehyde or methylol groups. 2) The adhesive strength of plywood prepared by this system was not inferior to conventional curing with ammonium chloride both in normal tests and in water-soaking test at 60C. The aromatic dihydrazide, isophthaloyl dihydrazide, had no decreases in superiority and bond strength after water-soaking compared with conventional curing with ammonium chloride.
Citation
Tomita, Bunichiro; Osawa, Hideaki; Hse, Chung-Yun; Myers, George E. 1989. New curing system of urea-formaldehyde resind with polyhydrazides. I. Curing with dihydrazie compounds. Journal of the Japan Wood Research Society 35(5):455-459
