Paper machine polymer systems and methods for their use.

摘要

A process for the preparation of paper suitable for use as cover sheets for the production of gypsum wallboard which comprises forming a suitable aqueous slurry of paper pulp, passing the slurry through papermaking apparatus wherein successively are added a neutral size material and a retention aid, and wherein the slurry is additionnally passed through a machine chest, a plurality of fan pumps, apparatus for forming the paper and subsequently drying the paper, the improvement which comprises the step of introducing a high molecular weight low cationic charge density retention aid polymer into the slurry immediately at the discharge situs of the fan pumps, whereby contaminants present in the slurry are retained and are not deposited on the surfaces of the papermaking apparatus. In a improved embodiment, a small amount of the high molecular weight low charge density polymer is utilized to replace cationic starch to act as a retention aid for the neutral size material, and a low molecular weight high charge density polymer is introduced into the machine chest as a coagulant to further promote the retention of contaminants present in the slurry to avoid their being deposited on the surfaces of the paper-making machine.