US3695995A - Oxygen-peracetic acid-chlorine dioxide pulp bleaching sequence - Google Patents

Oxygen-peracetic acid-chlorine dioxide pulp bleaching sequence Download PDF

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Publication number
US3695995A
US3695995A US40404A US3695995DA US3695995A US 3695995 A US3695995 A US 3695995A US 40404 A US40404 A US 40404A US 3695995D A US3695995D A US 3695995DA US 3695995 A US3695995 A US 3695995A
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United States
Prior art keywords
pulp
stage
peracetic acid
chlorine dioxide
oxygen
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Expired - Lifetime
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US40404A
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English (en)
Inventor
Sunanda K Roymoulik
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International Paper Co
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International Paper Co
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Publication date
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Publication of US3695995A publication Critical patent/US3695995A/en
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Classifications

    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
    • D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
    • D21C9/10—Bleaching ; Apparatus therefor
    • D21C9/1057—Multistage, with compounds cited in more than one sub-group D21C9/10, D21C9/12, D21C9/16

Definitions

  • the present invention relates to a novel 2 or 3 stage sequence for the delignification and bleaching of chemical pulps.
  • an unrefined, digested chemical pulp prepared by either the sulfate or sulfite process, and having a consistency of from about 3% to 35% and pref- 3,695,995 Patented Oct. 3, 1972 erably above 20%, based on the weight of the oven-dried pulp, is contacted or reacted with oxygen, at a temperature of from about 70 C. to about 140 C., preferably about 100 C., and a pressure of from about 60 psi.
  • protector compound selected from the group consisting of polysulfides having the formula Na S wherein x is an integer from 1 to 4, and Na S O Throughout this application the use of the term protector compound shall mean either an oxidizing or reducing agent which is capable of preventing the degradation and depolymerization of the cellulosic portion of the pulp by reacting with the carbonyl end groups, to convert them into hydroxyl groups when Na S O a reducing agent is used, or carboxyl groups, when Na s an oxidizing agent is used.
  • Na S is the preferred polysulfide.
  • the concentration of Na S O or Na S should be at least about 0.2% and preferably from about 2% to about 10%, based on the weight of the oven-dry pulp. If concentrations in excess of 10% are employed, costs are increased and no additional benefits are obtained.
  • the protectors contain only sodium and sulfur ions, both of which are present in sulfate or sulfite pulping systems, the efiiuent can be fed back into the chemical recovery system thereby preventing stream pollution which would otherwise occur if the efiiuent were emptied into the stream, as is conventionally done.
  • pulps having a lignin content of 5% or above are employed, the addition of from about 1% to about 5% of sodium hydroxide to the reaction mixture can speed up the reaction rate. Also, if the concentration of Na S O or Na S is 2% or less, sodium hydroxide can be employed to good advantage.
  • the partially bleached pulp of the first stage is subjected in the second stage to a bleach with peracetic acid.
  • concentration of the peracetic acid can be from about 0.5% to about 2.0%, preferably 1.0%, based on the weight of the oven-dried pulp, and the pulp consistency can be from about 10% to about 20%, preferably between about 10% and about 15%.
  • the reaction can be carried out at a temperature of from about 50 C. to about 90 C., with 70 C. being preferred.
  • the initial or starting pH must be within the range of from about 8.0 to about 12.0, with a range of from about 8.0 to about 10.0 being preferred.
  • the pH can be adjusted by adding Na CO and/or NaOH.
  • the initial pH must be adjusted to 8.0 or above to optimize the bleaching results.
  • the pulp after the first and second stages namely, oxygen (0) and peracetic acid (Pa), has a brightness of 60% or above and can be utilized as newsprint furnish.
  • the pulp is treated in a third stage with chlorine dioxide.
  • Either gaseous chloride dioxide or chlorine dioxide in solution can be employed.
  • the consistency of the pulp can be from about 10% to about 20%, preferably between 10% and 15%, based on the weight of the oven-dried pulp.
  • the concentration of the C10 can be from about 0.5% to about 2.0%, based on the weight of the oven-dried pulp.
  • the reaction can be carried out at a temperature of from about 50 C. to about C., preferably 70 C., and at a starting pH be tween 5.0 and 6.0 for a period of from about 30 minutes to about minutes.
  • the pulp consistency can be from about 10% to about 40%, with a consistency above 30% being preferred.
  • the reaction time can be reduced to about to minutes and can take place at a temperature of from about 20 C. to above 5 90 C., with 70 C. being preferred.
  • the semi-bleached pulp was then thoroughly washed with water and centrifuged. The brightness of the pulp was found to be 64% as measured in accordance with Tappi Standard Method T217.
  • the semi-bleached pulp was thoroughly washed with water and centrifuged. The brightness of the pulp was found to be 66% as measured in accordance with Tappi Standard Method T217.
  • EXAMPLE 2 A 100 grams sample of a hardwood pulp, which had been prepared in accordance with the kraft process and which had then been washed with deionized water, was bleached as follows. (The first stage was carried out in an electrically heated pressure reactor.)
  • the plup was further bleached in accordance with stage 2 below.
  • the O-Pa-D sequence of the present invention results in a fully bleached pulp of a brightness comparable to that obtained by a S-stage bleaching sequence and having a higher opacity.
  • the physical properties are equiva- 5 lent to those obtained by a conventional bleaching sequence.
  • a two-stage process for bleaching chemical pulps to a brightness of 60% or above which comprises:
  • a three-stage process for bleaching chemical pulps to a brightness of 80% or above which comprises:
  • chlorine dioxide in the third stage is chlorine dioxide in solution with a consistency of from about 10% to about 20%, based on the weight of the oven-dried pulp, and the temperature is about 70 C. for a period of from about 30 to about 120 minutes.

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  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Wood Science & Technology (AREA)
  • Paper (AREA)
US40404A 1970-05-25 1970-05-25 Oxygen-peracetic acid-chlorine dioxide pulp bleaching sequence Expired - Lifetime US3695995A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US4040470A 1970-05-25 1970-05-25

Publications (1)

Publication Number Publication Date
US3695995A true US3695995A (en) 1972-10-03

Family

ID=21910799

Family Applications (1)

Application Number Title Priority Date Filing Date
US40404A Expired - Lifetime US3695995A (en) 1970-05-25 1970-05-25 Oxygen-peracetic acid-chlorine dioxide pulp bleaching sequence

Country Status (7)

Country Link
US (1) US3695995A (de)
JP (1) JPS5510714B1 (de)
CA (1) CA939855A (de)
DE (1) DE2124325C3 (de)
FI (1) FI59432C (de)
FR (1) FR2095038A5 (de)
SE (1) SE375565C (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20080087390A1 (en) * 2006-10-11 2008-04-17 Fort James Corporation Multi-step pulp bleaching
WO2012037024A2 (en) 2010-09-16 2012-03-22 Georgia-Pacific Consumer Products Lp High brightness pulps from lignin rich waste papers

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AT378016B (de) * 1982-12-02 1985-06-10 Ver Edelstahlwerke Ag Verfahren zum entfaerben und/oder bleichen von zellulosematerial, insbesondere zellstoff, und vorrichtung zur durchfuehrung des verfahrens

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20080087390A1 (en) * 2006-10-11 2008-04-17 Fort James Corporation Multi-step pulp bleaching
WO2012037024A2 (en) 2010-09-16 2012-03-22 Georgia-Pacific Consumer Products Lp High brightness pulps from lignin rich waste papers
US8845860B2 (en) 2010-09-16 2014-09-30 Georgia-Pacific Consumer Products Lp High brightness pulps from lignin rich waste papers

Also Published As

Publication number Publication date
FI59432B (fi) 1981-04-30
SE375565B (de) 1975-04-21
FI59432C (fi) 1981-08-10
DE2124325C3 (de) 1980-06-19
DE2124325B2 (de) 1979-09-27
JPS5510714B1 (de) 1980-03-18
DE2124325A1 (de) 1971-12-09
FR2095038A5 (de) 1972-02-04
CA939855A (en) 1974-01-15
SE375565C (sv) 1984-07-16

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