New curing system for urea-formaldehyde resins with polyhydrazides. I. Curing with poly(methycrylol hydrazide)

Abstract

A new curing system for urea-formaldehyde (UF) resins was investigated using poly(methacryloyl hydrazide) as the curing reagent. Results were as follows: 1) Gel time and the water-soluble part of cured resins were determined as function of pH and molar ratio [hydrazide group/(free formaldehyde+methylol group)]. It was found that the reaction in this system proceeds for a short time under neutral conditions, and that the reaction of hydrazide groups with UF resin involves two stages with the second stage occuring at a rather high temperature. 2) The adhesive shear strength of lap-joint specimens prepared under the new system was comparable to that by conventional curing with ammonium chloride, although it decreased after watersoaking at 60°C. 3) The adhesive strength of plywood specimens decreased as the molar ratio increased.

Citation

Miyake, Katsumasa; Tomita, Bunichiro; Hse, Chung-Yun; Myers, George E. 1989. New curing system for urea-formaldehyde resins with polyhydrazides. I. Curing with poly(methycrylol hydrazide). Mokuzai Gakkaishi 35(8):736-741