PAPER MAKING PROCESS UTILIZING AN AMPHOTERIC MUCOUS STRUCTURE AS BINDER

摘要

The present invention refers to a paper making process with improved retention and binding of fillers and second grade fibers. It is characterized by the use of an amphoteric mucus like compound as binder. This compound is the reaction product between cationic starch of low charge density and an anionic polymer of high charge density as carboxymethyl cellulose. The compound has amphoteric and mucous characters and should be used for paper making, while in a unique transient structure. This structure is characterized by filler particles being enclosed and finely distributed in droplets of the highly hydrated but substantially water-insoluble mucous compound. According to the invention this transient structure may further be reorganized to a less hydrated and more resistant gel structure, still enclosing the filler. This gel structure can stand the draining forces on a paper machine wire. This structural reorganization is achieved by reaction with colloidal inorganic polymers of very high surface charge as polysilicic acid and polyaluminium compounds. The process yields papers of high strengths and filler retentions of more than 90% at a single wire passage even at extreme filler contents of 30-60% of the paper weight.