METHOD OF DEINKING WASTE PRINTED PAPER

摘要

A process for producing a deinked pulp from waste printed papers including adherent substances. In the process, adherent foreign substances are prevented from undergoing size reduction and a wastewater is reduced in COD. By the process, a deinked pulp reduced in residual ink content is produced. In an ink removal step in producing a deinked pulp from waste printed papers including adherent substances, the anhydride of a crystalline phyllosilicate is added in an amount of preferably 0.1-1.5 mass% based on the pulp on an oven-dry basis to conduct the ink removal treatment at a pH of 7.0-9.9. By the process, a deinked pulp reduced in residual ink can be produced even when the ink removal treatment is conducted under weakly alkaline to neutral conditions, which are generally regarded as effective in diminishing adherent foreign substances but poor in ink removal.