Studies on Copolymers of Polyurethane-Lignocellulosic Fiber as Paper Strengthening Agent

The mechanism of blocked-unblocked polyurethane was explored.The contents of isocyanate groups,the selection of block agent and accelerate agent,the time of the blocking reaction which influenced the effects of the blocked polyurethane were also investigated.And the application of blocked polyurethane in paper coating.Depended on the using of individual polyurethane and polyurethane was appended in the dope,we discovered the physical performance of paper both have been improved in different level.In the case of calefaction,the unblocked isocyanate reacted with the hydroxy of fibre,the chemical bonds would improve the wet strength of paper.