EP0285530A1 - Verfahren zum Bleichen von Zellstoffen - Google Patents
Verfahren zum Bleichen von Zellstoffen Download PDFInfo
- Publication number
- EP0285530A1 EP0285530A1 EP19880420102 EP88420102A EP0285530A1 EP 0285530 A1 EP0285530 A1 EP 0285530A1 EP 19880420102 EP19880420102 EP 19880420102 EP 88420102 A EP88420102 A EP 88420102A EP 0285530 A1 EP0285530 A1 EP 0285530A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- hydrogen peroxide
- temperature
- complexing
- sequestering agent
- action
- Prior art date
- Legal status (The legal status 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 status listed.)
- Granted
Links
- 238000004061 bleaching Methods 0.000 title claims abstract description 16
- 238000000034 method Methods 0.000 title claims description 21
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims abstract description 72
- 239000008139 complexing agent Substances 0.000 claims abstract description 13
- 239000003352 sequestering agent Substances 0.000 claims abstract description 13
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 15
- 230000000536 complexating effect Effects 0.000 claims description 13
- 238000005406 washing Methods 0.000 claims description 10
- 239000003795 chemical substances by application Substances 0.000 claims description 6
- 229920006395 saturated elastomer Polymers 0.000 claims description 5
- 150000001875 compounds Chemical class 0.000 claims description 4
- 239000004115 Sodium Silicate Substances 0.000 claims description 3
- 229910052911 sodium silicate Inorganic materials 0.000 claims description 3
- 230000000087 stabilizing effect Effects 0.000 claims description 3
- 239000002253 acid Substances 0.000 claims description 2
- 159000000003 magnesium salts Chemical class 0.000 claims description 2
- 229910052751 metal Inorganic materials 0.000 claims description 2
- 239000002184 metal Substances 0.000 claims description 2
- 150000002978 peroxides Chemical class 0.000 claims description 2
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 claims description 2
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims 1
- 229910052739 hydrogen Inorganic materials 0.000 claims 1
- 239000001257 hydrogen Substances 0.000 claims 1
- 238000010009 beating Methods 0.000 abstract 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 7
- 238000003825 pressing Methods 0.000 description 5
- 229920001131 Pulp (paper) Polymers 0.000 description 3
- 239000007864 aqueous solution Substances 0.000 description 3
- 238000010790 dilution Methods 0.000 description 3
- 239000012895 dilution Substances 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- CSNNHWWHGAXBCP-UHFFFAOYSA-L Magnesium sulfate Chemical compound [Mg+2].[O-][S+2]([O-])([O-])[O-] CSNNHWWHGAXBCP-UHFFFAOYSA-L 0.000 description 2
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 description 2
- 239000003153 chemical reaction reagent Substances 0.000 description 2
- 230000008030 elimination Effects 0.000 description 2
- 238000003379 elimination reaction Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 159000000000 sodium salts Chemical class 0.000 description 2
- GEHJYWRUCIMESM-UHFFFAOYSA-L sodium sulfite Chemical compound [Na+].[Na+].[O-]S([O-])=O GEHJYWRUCIMESM-UHFFFAOYSA-L 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- FEWFXBUNENSNBQ-UHFFFAOYSA-N 2-hydroxyacrylic acid Chemical class OC(=C)C(O)=O FEWFXBUNENSNBQ-UHFFFAOYSA-N 0.000 description 1
- BYHQTRFJOGIQAO-GOSISDBHSA-N 3-(4-bromophenyl)-8-[(2R)-2-hydroxypropyl]-1-[(3-methoxyphenyl)methyl]-1,3,8-triazaspiro[4.5]decan-2-one Chemical compound C[C@H](CN1CCC2(CC1)CN(C(=O)N2CC3=CC(=CC=C3)OC)C4=CC=C(C=C4)Br)O BYHQTRFJOGIQAO-GOSISDBHSA-N 0.000 description 1
- 229920003357 Clarene® Polymers 0.000 description 1
- QXNVGIXVLWOKEQ-UHFFFAOYSA-N Disodium Chemical compound [Na][Na] QXNVGIXVLWOKEQ-UHFFFAOYSA-N 0.000 description 1
- 235000015165 citric acid Nutrition 0.000 description 1
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid group Chemical class C(CC(O)(C(=O)O)CC(=O)O)(=O)O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 description 1
- 238000010668 complexation reaction Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000006837 decompression Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- -1 for example Chemical class 0.000 description 1
- 230000009931 harmful effect Effects 0.000 description 1
- SNXYIOIMZXSIDC-UHFFFAOYSA-A hexadecasodium;phosphonato phosphate Chemical compound [Na+].[Na+].[Na+].[Na+].[Na+].[Na+].[Na+].[Na+].[Na+].[Na+].[Na+].[Na+].[Na+].[Na+].[Na+].[Na+].[O-]P([O-])(=O)OP([O-])([O-])=O.[O-]P([O-])(=O)OP([O-])([O-])=O.[O-]P([O-])(=O)OP([O-])([O-])=O.[O-]P([O-])(=O)OP([O-])([O-])=O SNXYIOIMZXSIDC-UHFFFAOYSA-A 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 238000004898 kneading Methods 0.000 description 1
- 239000012978 lignocellulosic material Substances 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- 229910052943 magnesium sulfate Inorganic materials 0.000 description 1
- 235000019341 magnesium sulphate Nutrition 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 239000007800 oxidant agent Substances 0.000 description 1
- 235000015927 pasta Nutrition 0.000 description 1
- 238000004537 pulping Methods 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 230000009919 sequestration Effects 0.000 description 1
- 235000010265 sodium sulphite Nutrition 0.000 description 1
- 235000019832 sodium triphosphate Nutrition 0.000 description 1
- 239000011122 softwood Substances 0.000 description 1
- LSNNMFCWUKXFEE-UHFFFAOYSA-L sulfite Chemical compound [O-]S([O-])=O LSNNMFCWUKXFEE-UHFFFAOYSA-L 0.000 description 1
- 230000000930 thermomechanical effect Effects 0.000 description 1
- 230000002087 whitening effect Effects 0.000 description 1
- 239000002023 wood Substances 0.000 description 1
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
- D21C9/1005—Pretreatment of the pulp, e.g. degassing the pulp
Definitions
- the present invention relates to bleaching using hydrogen peroxide from mechanical, thermomechanical, chemo-mechanical, chemo-thermal pulp in the pulp and related fields.
- the dry matter yield of such an operation is always very high and can reach and even exceed 90%.
- acceptable bleaching cannot be obtained at a temperature between 100 ° C. and 150 ° C. in a water vapor atmosphere by means of hydrogen peroxide in the presence of an alkaline agent. only if the action of hydrogen peroxide is exerted on the material to be bleached together with an action of disintegration of the fibers by mechanical defibering or refining for a duration of the order of only a fraction of a second.
- the method of the present invention provides effective bleaching although it includes known conditions to oppose the achievement of such a result.
- the complexing or sequestering agent In the treatment with the complexing or sequestering agent, the latter is used in an amount of approximately 0.1% to 1% by weight of the weight of dry pulp. Unless specified or obvious, the quantities of products in all that follow are also expressed in percent by weight of the weight of dry dough.
- the complexing or sequestering agent is most often chosen from sodium tripolyphosphate, sodium tetrapyrophosphate, sodium salts of citric acids, nitrilotriacetic, ethylenediaminetetraacetic, diethylenetriaminepentaacetic.
- the treatment with the complexing or sequestering agent is most generally carried out at a pH value of between 4 and 8, the result of the invention then not depending on such a value.
- the consistency, percentage by weight of dough in the dry state in the treatment medium can, in the present treatment using a complexing or sequestering agent, vary within fairly wide limits, approximately 5% to 30% . It is most often between about 10% and 15% to best reconcile economy and efficiency of subsequent washing.
- the duration of treatment with a complexing or sequestering agent depends on the other parameters. It is generally between approximately 5 minutes and 2 hours.
- washing is meant the operation which consists in eliminating more or less completely and here effectively the liquid present in the dough. This elimination is carried out for example by pressing the dough on a filter or by means of a dilution-pressing sequence of the dough, repeated or not, in which the dilution is very generally ensured by water.
- the washing which follows the treatment by means of a complexing or sequestering agent is most often carried out at a temperature generally between approximately 20 ° C. and 90 ° C., often between 20 ° C. and 60 ° C. for essentially economic reasons.
- efficiency is meant, expressed in percent, the degree of elimination of the liquid phase present before washing in the dough.
- the action of hydrogen peroxide is exerted in the process of the invention preferably at a temperature above 120 °. C, for example 140 ° C and above.
- the amount of hydrogen peroxide used is that commonly accepted in the traditional bleaching of mechanical pulps and is therefore between approximately 0.5% and 10%, most often not less than approximately 2%.
- the alkaline agent present with the hydrogen peroxide which is very suitable for carrying out the invention is sodium hydroxide used most often at a rate of approximately 0.25% to 5% with a weight ratio of sodium hydroxide / hydrogen peroxide preferably between 0.2 and 1.
- the invention allows a duration of action of hydrogen peroxide both long enough to allow this product to fully develop its effectiveness, and advantageously reduced compared to that of traditional bleaching. It usually does not exceed 15 minutes and often even around 5 minutes.
- hydrogen peroxide exerts its action in a medium at a pressure practically equal to the pressure of saturated steam at the chosen temperature. This pressure is most often between 2 bar absolute and 40 bar absolute.
- the consistency of the paste as placed in the presence of hydrogen peroxide is preferably chosen to be as high as possible, remaining compatible with the production of a mixture of satisfactory homogeneity of the paste with the other products present.
- This quality of the mixture means that the consistency is generally limited to a value of not more than about 30%, or even 25%. However, it is rarely less than preferably around 10%.
- the present invention leads to high results in bleaching pulps of mechanical origin without the presence of compounds having a stabilizing effect for hydrogen peroxide being essential to the effectiveness of its action. This can however be improved by the presence of such compounds such as for example, the sodium silicate used most often at a rate of approximately 2% to 6%, the magnesium salts such as the magnesium sulfate used in a quantity generally included between 0.05% and 0.5%, derivatives of poly ( ⁇ -hydroxyacrylic acid) used in an amount of approximately 0.05% to 2%, such as Claresse® products.
- the process of the invention can be carried out batchwise or continuously in any installation mainly comprising mixing equipment, generally of the mixer type, in which the treatment can be carried out using the complexing or sequestering agent and the mixing of the initial paste. or washed with hydrogen peroxide and the alkaline agent, washing equipment such as, for example, filters, presses, finally, for the stage of action of hydrogen peroxide, pressure-resistant equipment and impervious to water vapor, such as a tubular reactor equipped for example with a screw type dough progression system or an autoclave.
- mixing equipment generally of the mixer type, in which the treatment can be carried out using the complexing or sequestering agent and the mixing of the initial paste. or washed with hydrogen peroxide and the alkaline agent, washing equipment such as, for example, filters, presses, finally, for the stage of action of hydrogen peroxide, pressure-resistant equipment and impervious to water vapor, such as a tubular reactor equipped for example with a screw type dough progression system or an autoclave.
- the treatment of the dough is carried out in a kneader using 0.5% of DTPA, for 15 minutes, at 60 ° C. in the case of examples 1 to 11, at 90 ° C. in the case of examples 12 to 14, at a pH of between 4 and 8 each time and which is the same in a given example and in the example provided for comparison, with a consistency equal to 10%.
- the following washing, each greater than 95% effective, is carried out at 60 ° C.
- the initial paste or the paste washed after treatment with DTPA is mixed with hydrogen peroxide, sodium hydroxide NaOH, the quantity of water sufficient to ensure the desired consistency here equal to 20%, and if necessary the silicate or Clarene® by kneading for less than 5 minutes at 20-25 ° C before being subjected to the action of hydrogen peroxide in a reactor of the pressure-resistant autoclave type, equipped with an airlock introduction of the paste, and impermeable to saturated steam which ensures the pressure at the temperature T chosen, -
- the degree of white of the paste collected after decompression of the autoclave and rapid cooling is measured (457 nm) in% using a CARL ZEISS spectrophotometer of the ELREPHO type.
- Each of the examples relates to the bleaching of 100 g of softwood millstone pulp with a degree of white equal to 53.7% and a dry weight equal to 38.2 g.
- This improvement is accompanied by a significant reduction in the consumption of hydrogen peroxide or, at the very least, practically does not increase it.
- a given degree of white is achieved with a substantial saving of hydrogen peroxide.
- Each of the examples relates to the bleaching of 100 g of chemothermal-mechanical pulp with sulphite with a white degree equal to 59.6% and a dry weight equal to 40 g.
Landscapes
- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Wood Science & Technology (AREA)
- Paper (AREA)
- Detergent Compositions (AREA)
- Treatment Of Fiber Materials (AREA)
- Dental Preparations (AREA)
- Noodles (AREA)
- Glass Compositions (AREA)
- Transition And Organic Metals Composition Catalysts For Addition Polymerization (AREA)
- Seasonings (AREA)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AT88420102T ATE84581T1 (de) | 1987-04-02 | 1988-03-29 | Verfahren zum bleichen von zellstoffen. |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FR8704844A FR2613388B1 (fr) | 1987-04-02 | 1987-04-02 | Procede de blanchiment de pates |
FR8704844 | 1987-04-02 |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0285530A1 true EP0285530A1 (de) | 1988-10-05 |
EP0285530B1 EP0285530B1 (de) | 1993-01-13 |
Family
ID=9349862
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP88420102A Expired - Lifetime EP0285530B1 (de) | 1987-04-02 | 1988-03-29 | Verfahren zum Bleichen von Zellstoffen |
Country Status (11)
Country | Link |
---|---|
EP (1) | EP0285530B1 (de) |
JP (1) | JPS63256786A (de) |
AT (1) | ATE84581T1 (de) |
AU (1) | AU606930B2 (de) |
CA (1) | CA1310797C (de) |
DE (2) | DE3877403T2 (de) |
ES (1) | ES2004846T3 (de) |
FI (1) | FI93749C (de) |
FR (1) | FR2613388B1 (de) |
NO (1) | NO173886C (de) |
NZ (1) | NZ224144A (de) |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0402335A2 (de) * | 1989-06-06 | 1990-12-12 | Eka Nobel Ab | Verfahren zum Bleichen von Lignocellulose enthaltenden Zellstoffen |
EP0456626A1 (de) * | 1990-04-23 | 1991-11-13 | Eka Nobel Ab | Verfahren zum Bleichen von Lignocellulose enthaltendem Material |
US5143581A (en) * | 1990-03-07 | 1992-09-01 | Atochem | Method of peroxide bleaching of pulp pretreated with a sequestering agent then with a sulphite and reducing agent |
WO1996001920A1 (en) * | 1994-07-11 | 1996-01-25 | Beloit Technologies Inc. | Peroxide bleaching process for cellulosic and lignocellulosic material |
US5658429A (en) * | 1991-04-30 | 1997-08-19 | Eka Nobel Ab | Process for bleaching of lignocellulose-containing pulp using a chelating agent prior to a peroxide-ozone-peroxide sequence |
Families Citing this family (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR2647641B1 (fr) * | 1989-06-05 | 1992-01-17 | Atochem | Procede de fabrication de pulpes vegetales blanchies |
SE467006B (sv) | 1989-06-06 | 1992-05-11 | Eka Nobel Ab | Blekning av kemisk massa med peroxid varvid massan foerst behandlas med en komplexbildare |
SE9001481L (sv) * | 1990-04-23 | 1991-10-24 | Eka Nobel Ab | Reduktion av halogenorganiska foereningar i blekeriavlopp |
FR2661431B1 (fr) * | 1990-04-30 | 1992-07-17 | Atochem | Procede de blanchiment au peroxyde de l'hydrogene de pates a papier a haut rendement. |
FR2661430B1 (fr) * | 1990-04-30 | 1992-07-17 | Atochem | Procede de blanchiment au peroxyde d'hydrogene de pates a papier a haut rendement. |
JP4580343B2 (ja) * | 2003-10-02 | 2010-11-10 | アンドリッツ インコーポレーテッド | リファイナーブローライン処理を伴うアルカリ過酸化物を用いた多段階メカニカルパルプ化方法 |
US8298373B2 (en) | 2008-02-07 | 2012-10-30 | University Of New Brunswick | Combined process of peroxide bleaching of wood pulps and addition of optical brightening agents |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR1159573A (fr) * | 1954-11-19 | 1958-06-30 | Fmc Corp | Blanchiment des pâtes de bois à température élevée |
US3251731A (en) * | 1963-02-11 | 1966-05-17 | Andrew J Gard | Bleaching of wood pulp with a sequestering agent and hydrogen peroxide |
Family Cites Families (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS5344563A (en) * | 1976-10-05 | 1978-04-21 | Ouchi Shinkou Kagaku Kougiyou | Preparation of benzothiazolylsulfenamide |
FI61215B (fi) * | 1976-11-23 | 1982-02-26 | Defibrator Ab | Saett och anordning att kontinuerligt framstaella lignocellulosahaltiga fibermaterial |
-
1987
- 1987-04-02 FR FR8704844A patent/FR2613388B1/fr not_active Expired - Lifetime
-
1988
- 1988-03-29 DE DE8888420102T patent/DE3877403T2/de not_active Expired - Fee Related
- 1988-03-29 DE DE198888420102T patent/DE285530T1/de active Pending
- 1988-03-29 NO NO881404A patent/NO173886C/no unknown
- 1988-03-29 ES ES198888420102T patent/ES2004846T3/es not_active Expired - Lifetime
- 1988-03-29 AT AT88420102T patent/ATE84581T1/de active
- 1988-03-29 EP EP88420102A patent/EP0285530B1/de not_active Expired - Lifetime
- 1988-03-31 FI FI881544A patent/FI93749C/fi not_active IP Right Cessation
- 1988-03-31 CA CA000563118A patent/CA1310797C/fr not_active Expired - Lifetime
- 1988-03-31 AU AU14067/88A patent/AU606930B2/en not_active Ceased
- 1988-04-02 JP JP63082116A patent/JPS63256786A/ja active Granted
- 1988-04-06 NZ NZ224144A patent/NZ224144A/xx unknown
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR1159573A (fr) * | 1954-11-19 | 1958-06-30 | Fmc Corp | Blanchiment des pâtes de bois à température élevée |
US3251731A (en) * | 1963-02-11 | 1966-05-17 | Andrew J Gard | Bleaching of wood pulp with a sequestering agent and hydrogen peroxide |
Non-Patent Citations (3)
Title |
---|
ABSTRACT BULLETIN OF THE INSTITUTE OF PAPER CHEMISTRY, vol. 55, no. 4, octobre 1984, page 462, résumé no. 4352, Appleton, Wisconsin, US; P. WHITTING et al.: "Factors affecting the use of chelating agents to aid the brightening of mechanical pulps", & CPPA ANN. MTG. (MONTREAL) PREPRINTS 70B: 339-348 (Feb. 2-3,1984) * |
TAPPI JOURNAL, vol. 68, no. 10, octobre 1985, pages 82-86, Atlanta, Georgia, US; T.-A. HAGGLUND et al.: "A new peroxide bleaching process for CTMP" * |
TAPPI JOURNAL, vol. 69, no. 10, octobre 1986, pages 120-125, Norcross, GA, US; C.W. DENCE et al.: "A survey of hydrogen peroxide bleaching of mechanical and chemimechanical pulp-factors affecting brightness" * |
Cited By (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0402335A2 (de) * | 1989-06-06 | 1990-12-12 | Eka Nobel Ab | Verfahren zum Bleichen von Lignocellulose enthaltenden Zellstoffen |
EP0402335A3 (de) * | 1989-06-06 | 1991-10-23 | Eka Nobel Ab | Verfahren zum Bleichen von Lignocellulose enthaltenden Zellstoffen |
EP0402335B1 (de) * | 1989-06-06 | 1993-11-10 | Eka Chemicals AB | Verfahren zum Bleichen von Lignocellulose enthaltenden Zellstoffen |
US5310458A (en) * | 1989-06-06 | 1994-05-10 | Eka Nobel Ab | Process for bleaching lignocellulose-containing pulps |
US5143581A (en) * | 1990-03-07 | 1992-09-01 | Atochem | Method of peroxide bleaching of pulp pretreated with a sequestering agent then with a sulphite and reducing agent |
EP0456626A1 (de) * | 1990-04-23 | 1991-11-13 | Eka Nobel Ab | Verfahren zum Bleichen von Lignocellulose enthaltendem Material |
US5143580A (en) * | 1990-04-23 | 1992-09-01 | Eka Nobel Ab | Process for reducing the amount of halogenated organic compounds in spent liquor from a peroxide-halogen bleaching sequence |
US5658429A (en) * | 1991-04-30 | 1997-08-19 | Eka Nobel Ab | Process for bleaching of lignocellulose-containing pulp using a chelating agent prior to a peroxide-ozone-peroxide sequence |
WO1996001920A1 (en) * | 1994-07-11 | 1996-01-25 | Beloit Technologies Inc. | Peroxide bleaching process for cellulosic and lignocellulosic material |
EP0919661A1 (de) * | 1994-07-11 | 1999-06-02 | Beloit Technologies, Inc. | Verfahren zum Peroxidbleichen von zellulosischen Materialien |
Also Published As
Publication number | Publication date |
---|---|
EP0285530B1 (de) | 1993-01-13 |
ES2004846T3 (es) | 1993-06-16 |
JPH0156197B2 (de) | 1989-11-29 |
CA1310797C (fr) | 1992-12-01 |
DE3877403T2 (de) | 1993-05-19 |
ES2004846A4 (es) | 1989-02-16 |
FI881544A (fi) | 1988-10-03 |
DE3877403D1 (de) | 1993-02-25 |
ATE84581T1 (de) | 1993-01-15 |
FR2613388A1 (fr) | 1988-10-07 |
FI93749B (fi) | 1995-02-15 |
NO881404D0 (no) | 1988-03-29 |
NZ224144A (en) | 1989-07-27 |
FI93749C (fi) | 1995-05-26 |
AU1406788A (en) | 1988-10-06 |
AU606930B2 (en) | 1991-02-21 |
NO173886C (no) | 1994-02-16 |
NO173886B (no) | 1993-11-08 |
JPS63256786A (ja) | 1988-10-24 |
FR2613388B1 (fr) | 1990-05-04 |
FI881544A0 (fi) | 1988-03-31 |
NO881404L (no) | 1988-10-03 |
DE285530T1 (de) | 1989-03-30 |
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