Mitsubishi Gas Chemical Company, Inc.

Wakana Uesugi

Tetsuo Koshitsuka

Kiyoshi Yoshida

Yosuke Uchida

Hiroyuki Nagatani

Kaoru Tsuyuki

Takahiro Cho

Ayano Kawae

Iori Tomoda

The invention provides a method for producing a peroxymonosulfuric acid solution with high stability, including the steps of mixing 35 mass % or more of hydrogen peroxide and 70 mass % or more of sulfuric acid to react them, cooling the reaction solution to 80&#xb0; C. or lower within five minutes after initiation of the mixing step, and diluting the reaction solution with water four times or more as much as the reaction solution by mass.

Method for producing peroxymonosulfuric acid and apparatus for continuously producing peroxymonosulfuric acid

A method for producing bleached pulp, including processing unbleached pulp obtained by cooking a lignocellulose substance, followed by treatment with peroxomonosulfuric acid and thereafter by multistage chlorine-free bleaching treatment starting from chlorine dioxide treatment; a method for producing bleached pulp, including processing unbleached pulp for alkali-oxygen bleaching followed by chlorine-free bleaching treatment or totally chlorine-free bleaching treatment to bleach it to a degree of brightness of from 70 to 89%, and further followed by treatment with peroxomonosulfuric acid; and paper produced by the use of the bleached pulp produced according to these production methods, at a papermaking pH of at most 6.

Process for producing bleached pulp

Provided are a method for producing bleached pulp, comprising processing unbleached pulp obtained by cooking a lignocellulose substance, for alkali-oxygen bleaching followed by treatment with peroxomonosulfuric acid and thereafter by multistage chlorine-free bleaching treatment starting from chlorine dioxide treatment; a method for producing bleached pulp, comprising processing the unbleached pulp for alkali-oxygen bleaching followed by chlorine-free bleaching treatment or totally chlorine-free bleaching treatment to bleach it to a degree of brightness of from 70 to 89%, and further followed by treatment with peroxomonosulfuric acid; and paper produced by the use of the bleached pulp produced according to these production methods, at a papermaking pH of at most 6. Provided are the efficient production methods for bleached pulp in which the color reversion resistance is enhanced in chlorine-free bleaching and the bleaching cost increase is prevented, and the paper produced by the use of the bleached pulp according to an acid papermaking process.

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Tokyo, Japan

Wakana Uesugi