| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for bleaching high-whiteness pulp of printed waste paper in which waste paper pulp having high whiteness is obtained by improving a bleaching method using an offset printing waste paper. SOLUTION: In a disintegrating process of waste paper raw material, a chelating agent is used in combination with thiourea dioxide and an alkali or the chelating agent and the thiourea dioxide are simultaneously used in combination with the alkali or the chelating agent, the thiourea dioxide are simultaneously used in combination with the alkali, an enzyme and sodium hypochlorite, and treatment using a combination of the chelating agent with the thiourea dioxide and the alkali and one-stage bleaching treatment using hydrogen peroxide are carried out in the disintegrating process or treatment using the combination of the chelating agent with the thiourea dioxide and the alkali and multi-stage bleaching treatment using hydrogen peroxide in a first stage and using the thiourea dioxide, the chelating agent and the alkali in a second stage are carried out in the disintegrating process. COPYRIGHT: (C)2006,JPO&NCIPI
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