To provide a method for bleaching, which is capable of producing a deinked waste paper pulp having a high degree of whiteness and a bleaching chemical basic unit lower than that of a conventional method by improving the bleaching effect of the deinked pulp with an alkaline hydrogen peroxide.
This pulp-forming process constituted of apparatus for producing deinked pulp having the high degree of whiteness, which consists of the combination of a disintegrating process of disintegrating printed waste paper, a screening process of removing dusts, a floatation process of deinking treatment, a bleaching process for bleaching and soaking treatments, a dispersing process of giving a mechanical shearing force, and a cleaning process of cleaning treatment, wherein the bleaching process consists of the continuous processes of two stages having a first bleaching process of alkaline hydrogen peroxide bleaching at 50 to 80°C and a second bleaching process of bleaching performed by elevating temperature up to 90 to 120°C.
COPYRIGHT: (C)2007,JPO&INPIT
Takahiro Miura
Daiji Ishimura
Atsushi Watanabe
Yasushi Ando
| JP2005240188A | ||||
| JP2005281914A |