WO2005121443A1 - Activateur pour le blanchiment de pate a papier - Google Patents

Activateur pour le blanchiment de pate a papier Download PDF

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Publication number
WO2005121443A1
WO2005121443A1 PCT/GB2005/002312 GB2005002312W WO2005121443A1 WO 2005121443 A1 WO2005121443 A1 WO 2005121443A1 GB 2005002312 W GB2005002312 W GB 2005002312W WO 2005121443 A1 WO2005121443 A1 WO 2005121443A1
Authority
WO
WIPO (PCT)
Prior art keywords
anhydride
carboxylic acid
process according
range
acid anhydride
Prior art date
Application number
PCT/GB2005/002312
Other languages
English (en)
Inventor
Alan Michael Marland
Alison Jane Mathews
Gary Miller
Original Assignee
Warwick International Group Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Warwick International Group Limited filed Critical Warwick International Group Limited
Priority to US11/570,140 priority Critical patent/US20070246177A1/en
Priority to CA002569467A priority patent/CA2569467A1/fr
Publication of WO2005121443A1 publication Critical patent/WO2005121443A1/fr

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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
    • D21C9/16—Bleaching ; Apparatus therefor with per compounds
    • D21C9/166—Bleaching ; Apparatus therefor with per compounds with peracids

Definitions

  • This invention relates to a process for generating a dilute solution of percarboxylic acid which is subsequently used to bleach wood or non wood pulp. More specifically, in this process the bleaching solution is formed by reaction of hydrogen peroxide with a carboxylic acid anhydride compound which behaves as a bleach activator. Wood and non wood pulp are valuable raw materials in the paper industry and it is desirable that a high degree of whiteness is obtainable. Oxygen based bleaching is used for pulp bleaching because of its environmental benefits and oxidising power. Hydrogen peroxide is increasingly being used in oxygen based pulp bleaching. Hydrogen peroxide, however, suffers from some performance disadvantages which become particularly important when an existing pulp bleaching sequence is being converted to operate with hydrogen peroxide.
  • in situ peracid can be generated by reaction of acetic anhydride with hydrogen peroxide directly in the bleaching stage although the equilibrium peracid is preferred and is what is used in the examples of this application.
  • EP-A-0670928 describes an identical method. However, whilst equilibrium peracid improves the bleaching it also introduces problems of handling and dosing, peracid in the pulp plant.
  • Further examples such as EP456032 describe the use of tetraacetylethylenediamine (TAED) as the bleach activator. Whilst this produces a very effective bleaching solution, generation of such a solution in certain circumstances may not prove to be economical for all mills.
  • TAED tetraacetylethylenediamine
  • a bleach activator suitable for solving this problem is acetic anhydride. Whilst the use of acetic anhydride as a bleach activator to produce peracetic acid is well documented, surprisingly better performance can be delivered using peracetic acid generated from acetic anhydride as compared to preformed peracetic acid. Furthermore there is yet to be developed a simple and inexpensive process by which good yields of peracid can be produced.
  • a process for the bleaching of cellulosic fibres comprising the steps of; a) treating a fresh water supply with a chelating agent to give a stabilised water supply; b) adding hydrogen peroxide to the stabilised water supply to form a hydrogen peroxide solution; c) adjusting the pH of the hydrogen peroxide solution by adding alkali; d) mixing the pH adjusted solution resulting from step (c) to allow complete formation of perhydroxyl ion; e) adding a carboxylic acid anhydride compound to the solution resulting from step (d); f) mixing the solution resulting from step (e) to allow complete formation of percarboxylic acid to give a dilute solution of percarboxylic acid; and g) contacting the percarboxylic acid solution with a suspension of cellulosic fibres.
  • the water used in step a) is of a temperature between 5°C-100°C, preferably between 10°C-50°C and more preferably between 15°C-30°C. At cooler temperatures the generation of the percarboxylic acid may be inhibited whilst at higher temperatures, although the generation would be rapid, it is anticipated that degradation of the percarboxylic acid species would be promoted. Chelating agent is added to the water in step a) prior to the addition of further components and is advantageous as it ensures that any trace metals which may be present in the supply are removed. Such trace metals could potentially promote the decomposition of hydrogen peroxide. A mixing step is preferably included to maximise the chelation of the trace metals.
  • the chelating agent is an aqueous phosphonic acid based chelating agent.
  • suitable phosphonic acid based chelating agents are polyamino methylene phosphonic acids such as based on ethylene diamine or diethylenetriamine.
  • Commercially available compounds of this type include Dequest SPE9505, Dequest 20605.
  • the chelating agent is Dequest SPE 9505 and/or Dequest 2066.
  • An aqueous phosphonic acid based chelating agent has been found to work best under the conditions of the method of the present invention.
  • the amount of chelating agent, eg phosphonic acid based agent, added to the water is 0.1-0.4wt%, more preferably 0.125-0.3%wt and most preferably 0.15-0.25%wt.
  • the amount of hydrogen peroxide added in step b), based on a 50% solution is a value in the range 0.5-6wt%, more preferably in the range 1.5-4.0wt% and most preferably in the range 1.75-2.5wt%. It is desirable that the addition of hydrogen peroxide is followed by an in line mixing step. This mixing step is often required because the water and hydrogen peroxide are transferred separately from their holding containers to the vessel in which the reaction proceeds. It is therefore beneficial to include a mixing step to ensure that a uniform solution is obtained.
  • the alkali is added in step c) in an amount to raise the pH of the solution from a value in the range 6-7 to a value in the range 10.5-11.5. It is important that this alkali addition occurs prior to step (d). This is because rendering the hydrogen peroxide solution of step b) alkaline promotes the formation of perhydroxyl ion with which the carboxylic acid anhydride compound preferentially reacts instead of water. If step c) was not included, the carboxylic acid anhydride compound would hydrolyse thus reducing the amount of percarboxylic acid eventually formed.
  • Suitable alkalis include potassium hydroxide, calcium hydroxide, magnesium hydroxide and sodium hydroxide.
  • the alkali is sodium hydroxide.
  • Sodium hydroxide is available as a 30w/w% or 50w/w% solution. Suitable amounts were determined by monitoring the pH. Preferably the amount of sodium hydroxide added based on a 50% solution is a value in the range 0.2-3wt%, more preferably in the range 0.4-1.5wt% and most preferably in the range 0.5-1 wt%.
  • step d further mixing step
  • the duration of this step is preferably at least one minute. This is important to optimise the extent of formation of the perhydroxyl ion in the subsequent steps.
  • the carboxylic acid anhydride compound added in step e) is selected from one or more of the group consisting of acetic anhydride, maleic anhydride, succinic anhydride, phthalic anhydride, malonic anhydride, benzoic anhydride and propanoic anhydride.
  • the amount of carboxylic acid anhydride compound added is in the range 0.02 - 0.6mol%, more preferably in the range 0.05 - 0.3mol% and most preferably in the range 0.075 - 0.15mol% and this addition is followed by a further important mixing step (step f)). This mixing step should be allowed to occur for at least 10 minutes. This is to maximise generation of the percarboxylic acid species.
  • the carboxylic acid anhydride compound comprises acetic anhydride.
  • Acetic anhydride has a flash point of 54°C and as such is classified as flammable.
  • a compound is classified as flammable where it has a flashpoint in the range of 21 °C-55°C. This means that the modification of old mill equipment, although minor, will require consideration of the
  • the flashpoint of acetic anhydride is modified by addition of a carboxylic acid anhydride with a higher flashpoint to form a mixture which has a flash point of 55.1 °C or higher such that it is not classified as flammable.
  • a mixture which has a flash point of 60°C or higher is formed.
  • the amount of carboxylic acid anhydride with a higher flashpoint added is such that the resulting mixture has a ratio of acetic anhydride to carboxylic acid anhydride with a higher flashpoint greater than 50:50 but less than or equal to 80:20.
  • the carboxylic acid anhydride with a higher flashpoint is maleic anhydride.
  • a 50:50 mixture of acetic anhydride: maleic anhydride is not commercially practical as, upon cooling, the maleic anhydride precipitates out of the solution.
  • the ratio of acetic anydride to maleic anhydride is 80:20.
  • the mixture consists of the acetic anhydride and further carboxylic acid anhydride with a higher flashpoint only. The mixture of acetic anhydride and carboxylic acid anhydride with a higher flashpoint can then be used as the carboxylic acid anhydride compound in the method for bleaching cellulosic fibres of the invention.
  • the method of increasing the flash point of acetic anhydride by mixing with a carboxylic acid anhydride with a higher flashpoint and the mixture itself form a second aspect of the invention.
  • the molar ratio of carboxylic acid anhydride compound to hydrogen peroxide added is preferably in the range 1 :1 to 1 :10, preferably 1 :1.5 to 1 :6, more preferably 1 :2 to 1 :4 . Most preferably the molar ratio is about 1 :3.
  • the resultant dilute percarboxylic acid solution formed in step f) will have a pH of approximately 5. Depending on the mill conditions, it may be necessary to increase the solution pH to suit the bleaching conditions required in the final step of the process, step g). Typically a conversion of carboxylic acid anhydride compound to percarboxylic acid of 90-95% is obtained.
  • the resultant solution contains percarboxylic acid in a concentration range of 0.1-10%, more preferably 0.25-5% and most preferably 0.5-2%.
  • the final step (step g)) of the process is to contact the dilute percarboxylic acid solution with a cellulosic fibre suspension e.g formed from pulp.
  • the pulp may be any sort of pulp, including chemical and mechanical pulp and mixture thereof, including recycled material. Wood and non wood fibres can be bleached using this process.
  • the product may be used directly to form paper or board or may be fully or partially dewatered to form a pulp intermediate for eventual paper or board manufacture.
  • the following examples give an indication of how effective this process is and demonstrate the high yield of percarboxylic acid which can be expected to be generated.
  • Figure 1 shows the percarboxylic acid release profile of formulations 1 -5 as detailed in Example 1 ;
  • Figure 2 shows the pH profile of formulations 1 -5 as detailed in
  • Example 1 Figure 3 shows the brownstock delignification of soft wood pulp using a 0.5% peracetic acid charge from anhydride sources formulations 1-5 in terms of Kappa as detailed in example 2; Figure 4 shows the brownstock delignification of soft wood pulp using a 0.5% peracetic acid charge from anhydride source formulations 1-5 in terms of ISO brightness as detailed in Example 2; Figure 5 shows the storage chest bleaching of fully bleached pulp using peracetic acid from formulations 1-5 measured in terms of ISO brightness as detailed in Example 3; and Figure 6 shows the recycled fibre (80:20 Newsprint: MOW) bleaching using peracetic acid from formulations 1-5 measured in terms of ISO Brightness as detailed in Example 4.
  • Figure 3 shows the brownstock delignification of soft wood pulp using a 0.5% peracetic acid charge from anhydride sources formulations 1-5 in terms of Kappa as detailed in example 2
  • Figure 4 shows the brownstock delignification of soft wood pulp using a 0.5% peracetic acid charge from anhydride source formulations 1-5 in terms of ISO brightness
  • Figure 7 shows a comparison of preformed and acetic anhydride derived peracetic acid on bleaching brownstock pulp.
  • Figure 8 shows a comparison of preformed and acetic anhydride derived peracetic acid on bleaching 80:20 Newsprint: MOW recycled furnish. Examples
  • various formulations were prepared. It was also the case that formulations containing an acetic anhydride/maleic anhydride solution were tested. The formulations prepared are as detailed below:
  • Dequest 2066 2g Dequest 2066 2g
  • P420 TAED based activator (PeroxyBoost (RTM))
  • each of the formulations were prepared according to the method of the present invention. More specifically, fresh water at a temperature in the range from 15-30°C was treated with 0.2wt% of Dequest 2066. 2wt% of a 50% hydrogen peroxide solution was added to the stabilised water supply, the pH of the resulting hydrogen peroxide solution was adjusted to a pH in the range from 10.5 to 11.5 by the addition 0.75wt% of a 50% solution of sodium hydroxide. The mixture was then mixed for a period of 1 minute to allow complete formation of the perhydroxyl ion. The bleach activator was added to this mixed solution in the amounts shown above respectively and the solution was mixed to allow complete formation of peracetic acid to give a dilute solution of peracetic acid.
  • Peracid release/pH profile The peracid release profile for each of formulations 1-5 was determined by taking measurements between 2 and 145 minutes. The solution temperatures were maintained at 25° C. pH profiles were also attained during the process. The results of the peracid release profile are shown in Table 1 and Figure 1. The pH profiles attained are illustrated in Table 2 and Figure 2.
  • Brownstock Delignification Using formulations 1-5, brownstock delignification was carried out.
  • the experimental conditions and results are summarised in Table 3.
  • kappa and ISO brightness data was recorded using International Standards, ISO 302-1981(E) and ISO 3688-1977 respectively. The results are also illustrated graphically in Figures 3 and 4.
  • the bleaching ability of the acetic anhydride derived peracetic acid solution was compared with the bleaching ability of a preformed peracetic acid. More specifically, bleaching formulation 4 was compared to a preformed commercially available peracetic acid (supplied by Aldrich), hereinafter referred to as formulation 6.
  • formulation 6 a preformed commercially available peracetic acid (supplied by Aldrich), hereinafter referred to as formulation 6.
  • brown stock delignification and recycled bleaching studies were performed using brown stock and 80:20 Newsprint: MOW pulps respectively. The studies were performed using a 0.1 %, 0.25% and 0.5% charge of peracetic acid (based on 100% peracetic acid) respectively at a temperature of 70°C and with a retention time of 120 minutes.
  • Formulation 4 was used at a pH in the range 8-8.5 and formulation 6 was used at a pH of 5 which represents the normal conditions under which it is used.
  • ISO brightness data was recorded using International Standard ISO 3688-1977. The results are shown graphically in Figures 7 and 8. The data shows that a superior bleaching performance is achieved using acetic anhydride derived peracetic acid as compared to preformed peracetic acid. Flash Point Analysis The flashpoints of various neat carboxylic acid anhydride compounds are illustrated in Table 4. Samples of acetic anhydride, maleic anhydride, 80:20 acetic anhydride: maleic anhydride and 50:50 acetic anhydride: maleic anhydride were prepared. The flash points of these solutions were determined using the Pensky Martens closed cup test. The results obtained are summarised in Table 5. Table 4

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  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Wood Science & Technology (AREA)
  • Paper (AREA)
  • Detergent Compositions (AREA)
  • Polyurethanes Or Polyureas (AREA)

Abstract

La présente invention a trait à un procédé pour le blanchiment de fibres cellulosiques comprenant les étapes suivantes: (a) la mise à disposition d'une alimentation en eau; (b) l'ajout de peroxyde d'hydrogène à l'alimentation en eau stabilisée pour former une solution de peroxyde d'hydrogène; (c) l'ajustement du pH de la solution de peroxyde d'hydrogène par l'ajout d'alcali; (d) le mélange de la solution à pH ajusté obtenue de l'étape (c) pour permettre la formation complète d'ion perhydroxyle; (e) l'ajout d'un composé anhydride d'acide carboxylique à la solution obtenue à l'étape (d); (f) le mélange de la solution obtenue à l'étape (e) pour permettre la formation complète de l'acide percarboxylique pour l'obtention d'une solution d'acide percarboxylique; et (g) la mise en contact de la solution avec une suspension de fibres cellulosiques.
PCT/GB2005/002312 2004-06-14 2005-06-10 Activateur pour le blanchiment de pate a papier WO2005121443A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
US11/570,140 US20070246177A1 (en) 2004-06-14 2005-06-10 Activator for Pulp Bleaching
CA002569467A CA2569467A1 (fr) 2004-06-14 2005-06-10 Activateur pour le blanchiment de pate a papier

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP04253546A EP1607519B1 (fr) 2004-06-14 2004-06-14 Activateur pour le blanchiment du pâte à papier
EP04253546.8 2004-06-14

Publications (1)

Publication Number Publication Date
WO2005121443A1 true WO2005121443A1 (fr) 2005-12-22

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ID=34930404

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB2005/002312 WO2005121443A1 (fr) 2004-06-14 2005-06-10 Activateur pour le blanchiment de pate a papier

Country Status (9)

Country Link
US (1) US20070246177A1 (fr)
EP (1) EP1607519B1 (fr)
AT (1) ATE386837T1 (fr)
CA (1) CA2569467A1 (fr)
DE (1) DE602004011911T9 (fr)
ES (1) ES2300713T3 (fr)
PL (1) PL1607519T3 (fr)
PT (1) PT1607519E (fr)
WO (1) WO2005121443A1 (fr)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8268122B2 (en) * 2005-12-02 2012-09-18 Akzo Nobel N.V. Process of producing high-yield pulp
DE102006028018A1 (de) * 2006-06-14 2007-12-20 Henkel Kgaa Aufhell-und/oder Färbemittel mit Estern und/oder Anhydriden
US20230212821A1 (en) * 2020-06-16 2023-07-06 Kemira Oyj Method for pitch control during bleaching

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3227655A (en) * 1957-11-25 1966-01-04 Fmc Corp Process for preparation of a bleaching agent
EP0456032A1 (fr) * 1990-04-25 1991-11-13 Hoechst Japan Limited Procédé de blanchiment de pâtes
WO1994012722A1 (fr) * 1992-11-27 1994-06-09 Eka Nobel Ab Procede pour blanchir la pate a papier contenant de la lignocellulose
GB2304126A (en) * 1995-08-10 1997-03-12 Warwick Int Group Pulp treatment process

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2377038A (en) * 1941-09-15 1945-05-29 Du Pont Manufacture of peracids
US4294575A (en) * 1979-01-02 1981-10-13 Monsanto Company Peroxide stabilization
FR2457339A1 (fr) * 1979-05-25 1980-12-19 Interox Procede pour la delignification et le blanchiment de pates cellulosiques chimiques et semi-chimiques
WO1994012721A1 (fr) 1992-11-27 1994-06-09 Eka Nobel Ab Procede de delignification de pulpe contenant de la cellulose ligneuse

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3227655A (en) * 1957-11-25 1966-01-04 Fmc Corp Process for preparation of a bleaching agent
EP0456032A1 (fr) * 1990-04-25 1991-11-13 Hoechst Japan Limited Procédé de blanchiment de pâtes
WO1994012722A1 (fr) * 1992-11-27 1994-06-09 Eka Nobel Ab Procede pour blanchir la pate a papier contenant de la lignocellulose
GB2304126A (en) * 1995-08-10 1997-03-12 Warwick Int Group Pulp treatment process

Also Published As

Publication number Publication date
PL1607519T3 (pl) 2008-07-31
DE602004011911T9 (de) 2009-01-02
EP1607519A1 (fr) 2005-12-21
ES2300713T3 (es) 2008-06-16
US20070246177A1 (en) 2007-10-25
DE602004011911D1 (de) 2008-04-03
PT1607519E (pt) 2008-04-16
EP1607519B1 (fr) 2008-02-20
DE602004011911T2 (de) 2008-08-28
ATE386837T1 (de) 2008-03-15
CA2569467A1 (fr) 2005-12-22

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