| 摘要 |
<p>PURPOSE: To stably produce deinked pulp having slight variability of whiteness caused by difference in time elapsed after printing by using printed old paper as a raw material. CONSTITUTION: Printed old paper comprising old newspaper and flyer old paper of offset printing elapsed for about one year after printing is fed to a disintegrator, mixed with water, a deinking agent composed of a surfactant, a chelating agent such as EDTA and 0.005-0.02wt.% based on pulp of a sodium hypochlorite and a cellulase and/or a xylanase having pH4.5 to pH8.5 as optimum pH without adding an alkali chemical, dissociated and oxidized at 40-60 deg.C for 1 to 2 hours. Then the pulp is passed through a concentration process and an alkali immersion process using hydrogen peroxide and separated from ink by a separating process to give deinked pulp.</p> |
