| abstract |
(57) [Summary] [Purpose] In making paperboard from waste paper pulp as a main raw material, in order to increase the papermaking speed, the total yield is improved, the drainage speed is improved, and the drying property is improved. [Structure] After adding a quaternary ammonium salt type polymer coagulant to the coagulation-inhibiting substances such as binders in the disintegrated pulp of waste paper, acryloyloxy having excellent coagulability is added to the stock after the coagulation is improved. The above object can be achieved by adding an ethyl quaternary ammonium salt type cationic polymer flocculant. Examples of the quaternary ammonium salt type polymer coagulant include polydimethyldiallylammonium salt. |