Global Patent Index - EP 0797703 B1

EP 0797703 B1 20000209 - PEROXIDE BLEACHING PROCESS FOR CELLULOSIC AND LIGNOCELLULOSIC MATERIAL

Title (en)

PEROXIDE BLEACHING PROCESS FOR CELLULOSIC AND LIGNOCELLULOSIC MATERIAL

Title (de)

VERFAHREN ZUM PEROXIDBLEICHEN VON CELLULOSISCHEN UND LIGNOCELLULOSISCHEN MATERIALEN

Title (fr)

PROCEDE DE BLANCHIMENT AU PEROXYDE DE SUBSTANCES CELLULOSIQUES ET LIGNOCELLULOSIQUES

Publication

EP 0797703 B1 20000209 (EN)

Application

EP 95926123 A 19950629

Priority

  • US 9508137 W 19950629
  • US 27353994 A 19940711

Abstract (en)

[origin: WO9601920A1] A method for bleaching cellulosic and lignocellulosic pulp using hydrogen peroxide as a bleaching reagent, utilizes a two-step reaction, viz. a short high temperature step at a pressure sufficient to suppress boiling and a longer atmospheric pressure reduced temperature step to consume a substantial portion of the hydrogen peroxide remaining after the short phase. The method includes the steps of introducing pulp (15), at a consistency of 10 %-18 %, to a mixer (100) in which the pulp is heated to a temperature above 100 DEG C; adding sufficient sodium hydroxide to bring the pulp to a pH of 8.5; adding sufficient hydrogen peroxide (36) to equal from about 0.5 %-5.0 %, by weight, of the pulp; passing the pulp through a pressurized reactor column (400) at a rate providing a reaction time in the column of between 1 and 30 minutes; and depositing the pulp in a reaction tower and allowing the reaction to proceed for 1-5 hours until a substantial portion of the residual hydrogen peroxide has been consumed. It may be desirable to introduce the pulp to a mixer and add alkali to reactivate residual hydrogen peroxide by bringing the pulp to a pH of at least 9 between bleaching steps.

IPC 1-7

D21C 9/16; D06L 3/02; D21C 9/10

IPC 8 full level

D21C 9/10 (2006.01); D21C 9/153 (2006.01); D21C 9/16 (2006.01)

CPC (source: EP)

D21C 9/1026 (2013.01); D21C 9/1057 (2013.01); D21C 9/163 (2013.01)

Designated contracting state (EPC)

AT DE ES PT SE

DOCDB simple family (publication)

WO 9601920 A1 19960125; AT 189716 T 20000215; BR 9508388 A 19980714; CA 2194880 A1 19960125; CN 1176673 A 19980318; DE 69515066 D1 20000316; DE 69515066 T2 20010419; DE 797703 T1 19980219; EP 0797703 A1 19971001; EP 0797703 B1 20000209; EP 0919661 A1 19990602; ES 2107399 T1 19971201; ES 2107399 T3 20000701; FI 970104 A0 19970110; FI 970104 A 19970310; JP 2787618 B2 19980820; JP H09508945 A 19970909; PT 797703 E 20000731; RU 2141016 C1 19991110; ZA 955290 B 19961227

DOCDB simple family (application)

US 9508137 W 19950629; AT 95926123 T 19950629; BR 9508388 A 19950629; CA 2194880 A 19950629; CN 95194090 A 19950629; DE 69515066 T 19950629; DE 95926123 T 19950629; EP 95926123 A 19950629; EP 98204179 A 19950629; ES 95926123 T 19950629; FI 970104 A 19970110; JP 50432895 A 19950629; PT 95926123 T 19950629; RU 97101657 A 19950629; ZA 955290 A 19950626