Patent ID: 6238520
Filing Date: 2001-05-29
Classification: B64D,D21H,F02C,F16B,G10K

Abstract:
A process of making paper containing starch, comprisingproviding a cellulosic thin stock suspension,flocculating the suspension by adding an aqueous solution of polymeric retention aid and thereby forming a flocculated suspension,optionally shearing the flocculated suspension and reflocculating the sheared suspension by adding aqueous anionic bridging coagulant and thereby forming a reflocculated suspension,draining the flocculated or reflocculated suspension through a moving screen to form a wet sheet, andcarrying the sheet through a heated drying zone and thereby forming a dry sheet,wherein the process also comprisesproviding a coagulated slurry which contains undissolved starch particles and which is substantially free of filler by combining undissolved starch particles and cationic polymeric flocculant and an anionic microparticulate network agglomeration aid to give network flocculation of the network agglomeration aid in which the starch particles are trapped, andadding the coagulated slurry to the cellulosic suspension, andthe undissolved starch particles are heated during the drying and release dissolved starch into the sheet in the presence of moisture, wherein the dry sheet retains at least 2% by weight of starch.