Abstract
Polyvinyl acetate emulsion (EPVAc) was synthesized by using acetoacetylated PVA (AAPVA) asthe protective colloid (A1O), and the isocyanate chemical compound (pMDI) was added to this as thecross-linking agent.The physical properties of the film and wood-bonding performance were examined based on a comparison with typical EPVAc (NIO), and the following results were obtained.1) In the AlO films to which pMDI was added, at all heat treatment conditions, a rubber plateau, whichis unique to the cross-linked polymer, was observed near 180 to 200℃.And the shift of the E"shoulder of dynamic viscoelasticity to the high temperature side was larger than in NIO, and thistrend became more prominent with an increase in the addition of pMDI.2) In the films that were heat-treated at 120℃, the percentage of moisture absorption of A10 decreased greatly, with the percentage of moisture absorption of A10 being considerably lower than that of N10.Further more, there was a trend showing a decrease in moisture absorption with an increase in the amount of pMDI added. The amount dissolved in the A10 films was smaller in the films that were heated at a higher temperature and for a longer periodof time.3)The water proof adhesion performance of A10, which was heat-treated at 120℃, showed values 30% to 50% higher than those cured at 20℃.The water proof adhesion performance of EPVAc improvedwith an increase in the addition of pMDI with the effect being particularly remarkable in A10.
