Nippon Paper Industries Co., Ltd.

Aikawa Iron Works Co., Ltd.

Hisashi Iwabuchi

Yoshihiko Aikawa

Shisei Goto

Takeshi Iimori

Chie Yuzawa

Yasuyuki Kamijo

Isao Aoki

Mitsuhiro Sugino

Takashi Onizaki

The object of the present invention is to provide a process for producing deinked pulp from recovered paper containing stickies while preventing excessive reduction in the size of stickies, lowering the COD of effluents, and producing deinked pulp with a smaller residual ink content. In the ink detachment stage of the process for producing deinked pulp from recovered paper containing stickies, an anhydride of crystalline layered silicate is added, preferably in an amount of 0.1-1.5 weight % of absolute-dry pulp, and a deinking treatment is performed at a pH of 7.0-9.9. In the present invention, the deinking treatment is performed in a weakly alkaline to neutral region which is generally said to be effective in reducing the amount of stickies but less effective in ink detachment and, yet, deinked pulp having a smaller amount of residual ink can be produced.

Method of deinking recovered paper

A kneader includes a casing with a papermaking material supply opening and a papermaking material outlet located below the papermaking material supply opening; at least first, second, third and fourth rotational shafts provided inside the casing; first blades attached to the first rotational shaft; second blades attached to the second rotational shaft; third blades attached to the third rotational shaft; and fourth blades attached to the fourth rotational shaft. The first rotational shaft and the second rotational shaft are located at the same height and are arranged parallel to each other, and the third rotational shaft and the fourth rotational shaft are located at the same height and are arranged parallel to each other. The third rotational shaft is located under the first rotational shaft and the fourth rotational shaft is located under the second rotational shaft, respectively.

Kneader

Growing community of inventors

Tokyo, Japan

Hisashi Iwabuchi