EP0395792B1 - Procedure for the bleaching of pulp - Google Patents
Procedure for the bleaching of pulp Download PDFInfo
- Publication number
- EP0395792B1 EP0395792B1 EP89117233A EP89117233A EP0395792B1 EP 0395792 B1 EP0395792 B1 EP 0395792B1 EP 89117233 A EP89117233 A EP 89117233A EP 89117233 A EP89117233 A EP 89117233A EP 0395792 B1 EP0395792 B1 EP 0395792B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- bleaching
- pulp
- oxygen
- chlorine
- enzyme treatment
- 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.)
- Revoked
Links
- 238000004061 bleaching Methods 0.000 title claims abstract description 65
- 238000000034 method Methods 0.000 title claims abstract description 38
- 238000011282 treatment Methods 0.000 claims abstract description 60
- OSVXSBDYLRYLIG-UHFFFAOYSA-N dioxidochlorine(.) Chemical compound O=Cl=O OSVXSBDYLRYLIG-UHFFFAOYSA-N 0.000 claims abstract description 48
- 108090000790 Enzymes Proteins 0.000 claims abstract description 43
- 102000004190 Enzymes Human genes 0.000 claims abstract description 43
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 43
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 43
- 239000001301 oxygen Substances 0.000 claims abstract description 43
- 239000000126 substance Substances 0.000 claims abstract description 31
- 239000004155 Chlorine dioxide Substances 0.000 claims abstract description 24
- 235000019398 chlorine dioxide Nutrition 0.000 claims abstract description 24
- 230000003647 oxidation Effects 0.000 claims abstract description 21
- 238000007254 oxidation reaction Methods 0.000 claims abstract description 21
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 claims abstract description 20
- 239000000460 chlorine Substances 0.000 claims abstract description 20
- 229910052801 chlorine Inorganic materials 0.000 claims abstract description 19
- KZBUYRJDOAKODT-UHFFFAOYSA-N Chlorine Chemical compound ClCl KZBUYRJDOAKODT-UHFFFAOYSA-N 0.000 claims abstract description 11
- 229940088598 enzyme Drugs 0.000 claims description 40
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 21
- 239000003513 alkali Substances 0.000 claims description 12
- 239000000203 mixture Substances 0.000 claims description 10
- 229940059442 hemicellulase Drugs 0.000 claims description 4
- 108010002430 hemicellulase Proteins 0.000 claims description 4
- 108010059892 Cellulase Proteins 0.000 claims description 2
- 108090000371 Esterases Proteins 0.000 claims description 2
- 108010059820 Polygalacturonase Proteins 0.000 claims description 2
- 229940106157 cellulase Drugs 0.000 claims description 2
- 108010093305 exopolygalacturonase Proteins 0.000 claims description 2
- 239000011122 softwood Substances 0.000 claims description 2
- 239000007844 bleaching agent Substances 0.000 abstract description 17
- 238000005406 washing Methods 0.000 abstract description 11
- 231100000167 toxic agent Toxicity 0.000 abstract description 2
- 238000002474 experimental method Methods 0.000 description 26
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 9
- 230000000694 effects Effects 0.000 description 6
- 150000004045 organic chlorine compounds Chemical class 0.000 description 6
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 5
- 229920005610 lignin Polymers 0.000 description 5
- 229910021653 sulphate ion Inorganic materials 0.000 description 5
- 239000007857 degradation product Substances 0.000 description 4
- 150000001805 chlorine compounds Chemical class 0.000 description 3
- 230000001590 oxidative effect Effects 0.000 description 3
- 238000000746 purification Methods 0.000 description 3
- 231100000331 toxic Toxicity 0.000 description 3
- 230000002588 toxic effect Effects 0.000 description 3
- VGVRPFIJEJYOFN-UHFFFAOYSA-N 2,3,4,6-tetrachlorophenol Chemical class OC1=C(Cl)C=C(Cl)C(Cl)=C1Cl VGVRPFIJEJYOFN-UHFFFAOYSA-N 0.000 description 2
- 101710121765 Endo-1,4-beta-xylanase Proteins 0.000 description 2
- 229920002488 Hemicellulose Polymers 0.000 description 2
- 235000008331 Pinus X rigitaeda Nutrition 0.000 description 2
- 235000011613 Pinus brutia Nutrition 0.000 description 2
- 241000018646 Pinus brutia Species 0.000 description 2
- 229920001131 Pulp (paper) Polymers 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 230000001627 detrimental effect Effects 0.000 description 2
- 238000003912 environmental pollution Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 239000007800 oxidant agent Substances 0.000 description 2
- 241000196324 Embryophyta Species 0.000 description 1
- 244000155172 Podocarpus elatus Species 0.000 description 1
- 235000003209 Podocarpus elatus Nutrition 0.000 description 1
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 1
- 241000223259 Trichoderma Species 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 229920002678 cellulose Polymers 0.000 description 1
- 239000001913 cellulose Substances 0.000 description 1
- 238000005660 chlorination reaction Methods 0.000 description 1
- 229910001902 chlorine oxide Inorganic materials 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 230000029087 digestion Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- 238000009533 lab test Methods 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 239000005416 organic matter Substances 0.000 description 1
- 238000009896 oxidative bleaching Methods 0.000 description 1
- 238000004537 pulping Methods 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 239000001117 sulphuric acid Substances 0.000 description 1
- 235000011149 sulphuric acid Nutrition 0.000 description 1
- 239000002351 wastewater 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
- D21C9/12—Bleaching ; Apparatus therefor with halogens or halogen-containing compounds
- D21C9/14—Bleaching ; Apparatus therefor with halogens or halogen-containing compounds with ClO2 or chlorites
- D21C9/144—Bleaching ; Apparatus therefor with halogens or halogen-containing compounds with ClO2 or chlorites with ClO2/Cl2 and other bleaching agents in a multistage process
-
- 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
- D21C5/00—Other processes for obtaining cellulose, e.g. cooking cotton linters ; Processes characterised by the choice of cellulose-containing starting materials
- D21C5/005—Treatment of cellulose-containing material with microorganisms or enzymes
-
- 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
-
- 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
- D21C9/147—Bleaching ; Apparatus therefor with oxygen or its allotropic modifications
Definitions
- the present invention relates to a procedure for the bleaching of pulp, in which procedure the oxidating bleaching chemical is oxygen. Reference is made to EP-A-0 383 999.
- Especially pulp obtained from a sulphate pulping process is of brown colour, which is mainly due to the lignin remaining in the pulp.
- Lignin is removed from the pulp by bleaching, which is a process consisting of several stages. During this process, the pulp is treated alternately with oxidizing, lignin-degrading chemicals and chemicals dissolving the degradation products. Oxidizing agents commonly used are oxygen and chlorine-containing chemicals, whereas alkali solutions are used for eliminating the degradation products.
- the spent bleach liquors causing the worst environmental pollution load are produced during the washing following the first chlorination and the first alkali treatment in the bleaching process.
- Various methods have been employed to reduce the pollution load, e.g. by replacing chlorine gas with chlorine dioxide or using oxygen as the oxidizing agent in the first bleaching stage, or by biological purification of the spent bleach liquor.
- the results achieved by these methods have not been completely satisfactory.
- the amounts of chlorophenols and other toxic chlorine compounds in the spent bleach liquor have been significantly reduced by employing chlorine dioxide and oxygen bleaching, it has not been possible to achieve a sufficient reduction in the chemical oxygen demand values of the liquors. Therefore, the methods referred to have required the employment of efficient biological purification.
- EP-A-0 383 999 has an earlier priority date than this application, however, was published later. The same is true for WO-A-8 908 738.
- This document is directed towards the effect of the enzyme treatment on the reduction of the chlorine content of bleached pulp. As is mentioned therein, chlorine chemicals are used in the bleach, whereby the proportion of chlorine dioxide is small.
- the object of the present invention is to achieve a solution that enables the toxic content and the value of chemical oxygen demand of the spent bleach liquor to be reduced so as to reduce the need for purification of the liquor.
- the invention is based on oxygen bleaching and it is characterized in that oxygen is used in the first oxidation stage of the bleaching process, that the pulp is subjected to enzyme treatment, and that after the oxygen bleaching and enzyme treatment, the pulp is washed.
- enzyme treatment involves an essential reduction in the amount of toxic compounds in the spent bleach liquor while at the same time reducing its chemical oxygen demand, especially when the oxidizing chemical used in the first bleaching stage is oxygen.
- oxidizing chemical i.e. pure chlorine gas
- the pulp can be subjected to enzyme treatment and washing before the first oxidation stage.
- a preferable alternative solution is to carry out the enzyme treatment and washing after the first oxidation stage.
- the enzyme breaks down hemicellulose and/or lignin contained in the pulp and renders the pulp more spongy, thus enhancing the effect of the chemicals in subsequent oxidation and alkali treatment stages.
- the degradation products are removed and can be directed to incineration so that they will not contribute to the pollution load at all but are instead utilized in the energy handling system of the plant.
- the subsequent oxidation stages after oxygen bleaching can be implemented using a bleaching chemical containing chlorine, e.g. chlorine gas and/or chlorine dioxide.
- a bleaching chemical containing chlorine e.g. chlorine gas and/or chlorine dioxide.
- the production of detrimental chlorine compounds will thus be limited to these process stages, and to minimize the amounts of these compounds it is preferable to use chlorine dioxide to as large an extent as possible. This makes it possible to reduce the content of organic chlorine compounds in the spent bleach liquor by more than 70% even in the bleaching of softwood pulp. This is a result unattainable with previously known bleaching methods.
- the bleaching of pulp by the procedure of the invention can be performed by employing alternate oxidation and alkali phases and washing the pulp after each of these phases to remove the bleaching chemicals and degradation products.
- the enzyme treatment in the procedure of the invention is preferably carried out in a temperature range of 10-90 °C, the most suitable range being 40-80 °C, with pH values in the range 3.0-10.0, most suitably 4.0-8.0.
- the enzyme used can be a hemicellulase, cellulase, pectinase, esterase or a mixture of these.
- a diluted enzyme mixture KD 50 (hemicellulase) was added to 220 g of dry matter obtained from pine sulphate pulp (with a dry matter content of 30%) so that a mixture with a consistency of 10% and a xylanase activity of 5 U/g of pulp dry matter was obtained.
- the temperature in the enzyme treatment was 55 °C and the duration of treatment 2 h.
- the pulp was subjected to preliminary oxygen bleaching.
- the acidity of the pulp was adjusted to pH 12.
- the temperature was 100 °C, overpressure 2 bar and duration of treatment 45 min.
- the pulp was washed in a Buchner funnel with a 20-fold amount of water.
- the pulp was subjected to an oxidizing bleaching treatment using a mixture containing 50 % chlorine dioxide and 50 % chlorine gas. Of this mixture, a dose equal to 2.0 x kappa number after oxygen bleaching was used. Treatment temperature was 40 °C and duration 45 min. After oxidation the pulp was washed in a Buchner funnel with a 20-fold amount of water.
- the mass was subjected to an alkali treatment using a 5 % sodium hydroxide solution in a dose of 0.9 x kappa. Consistency of solution was 10 %, treatment temperature 60 °C and duration of treatment 90 min. After the alkali treatment the pulp was washed in the same way as after oxidation.
- the bleaching was continued by repeating the oxidation and alkali phases and then once more the oxidation phase and washing the pulp between these phases as described above.
- the amount of chlorine dioxide in the second oxidation phase was 26 % and in the third phase 13 % of the amount of chlorine dioxide in the first oxidation phase.
- the dosage of sodium hydroxide was 1 % of the amount of chemical pulp.
- the liquids obtained from the washing stages phases after oxidation and enzyme treatment can be burned in a soda recovery boiler, in which case the amount of organic matter left in the spent bleach liquor is substantially smaller than in conventional chlorine bleaching and also smaller than in oxygen bleaching carried out without using an enzyme.
- Preliminary oxygen bleaching of 670 g of brown pine sulphate pulp was performed as follows: The pH value of the pulp was adjusted to 12 using NaOH, whereupon the pulp was subjected to a 45-min. oxygen treatment in an autoclave at a temperature of 100 °C and an oxygen overpressure of 2 bar.
- the pulp was acidated with sulphuric acid to pH 6.
- An amount of diluted enzyme mixture (Trichoderma [r] hemicellulase MK 901, Cultor Oy) was then added to the pulp so that a mixture consistency of 10 % and xylanase activity of 5 U/g of pulp dry matter was obtained.
- the pulp was subjected to a 2-hour enzyme treatment at 55 °C.
- the pulp was subjected to an oxidating bleaching treatment using chlorine dioxide in a dosage of 6.6 % of pulp dry matter. Consistency of the mixture was 10 %, temperature during treatment 70 °C, and duration of treatment 180 min. After the treatment the pulp was washed in a Buchner funnel with a 20-fold amount of water.
- the pulp was treated with NaOH (amount of NaOH 1 % of the dry matter of the pulp) for 90 min. Viscosity of the pulp was 10 %. After treatment, the pulp was washed with a 20-fold amount of water.
- the pulp was subjected to a chlorine dioxide treatment.
- the dosage of chlorine dioxide was 3.3 % of pulp dry matter, mixture viscosity 10 %, treatment temperature 75 °C and duration 240 min. After treatment, the pulp was again washed with a 20-fold amount of water.
- Experiment 5 The pulp was treated as in experiment 4 except for the first chlorine chemical treatment phase, in which the chlorine chemical was 80 % chlorine dioxide and 20 % chlorine gas. The dosage of active chlorine was 2.3 x kappa. In the next chlorine dioxide treatment phase the chemical was 100 % chlorine dioxide, and the dosage was 2.9 %.
- Such a procedure allows the amount of organing chlorine compounds in the spent bleach liquor to be substantially reduced, even by more than 70 %. If the spent bleach liquors from all those stages which precede bleaching stages involving chlorine chemicals are subjected to burning, then the chemical oxygen demand of the spent bleach liquor will also be reduced by more than 50 %.
Landscapes
- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Wood Science & Technology (AREA)
- Chemical & Material Sciences (AREA)
- Biochemistry (AREA)
- Microbiology (AREA)
- Paper (AREA)
- Noodles (AREA)
- Cereal-Derived Products (AREA)
- Table Devices Or Equipment (AREA)
- Bakery Products And Manufacturing Methods Therefor (AREA)
- Investigating Or Analysing Biological Materials (AREA)
- Hard Magnetic Materials (AREA)
- Agricultural Chemicals And Associated Chemicals (AREA)
- Detergent Compositions (AREA)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AT89117233T ATE91518T1 (de) | 1989-05-04 | 1989-09-18 | Verfahren zum bleichen von zellstoff. |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FI892151A FI86896B (fi) | 1989-05-04 | 1989-05-04 | Foerfarande foer blekning av cellulosamassa. |
FI892151 | 1989-05-04 |
Publications (3)
Publication Number | Publication Date |
---|---|
EP0395792A2 EP0395792A2 (en) | 1990-11-07 |
EP0395792A3 EP0395792A3 (en) | 1991-01-16 |
EP0395792B1 true EP0395792B1 (en) | 1993-07-14 |
Family
ID=8528357
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP89117233A Revoked EP0395792B1 (en) | 1989-05-04 | 1989-09-18 | Procedure for the bleaching of pulp |
Country Status (8)
Country | Link |
---|---|
EP (1) | EP0395792B1 (fi) |
JP (1) | JPH02293486A (fi) |
AT (1) | ATE91518T1 (fi) |
CA (1) | CA1339593C (fi) |
DE (1) | DE68907593D1 (fi) |
ES (1) | ES2045320T3 (fi) |
FI (1) | FI86896B (fi) |
NO (1) | NO172355C (fi) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US7541175B1 (en) | 2000-12-22 | 2009-06-02 | Iogen Energy Corporation | Alkaline extraction stages comprising xylanase |
Families Citing this family (19)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE69025405T2 (de) * | 1989-08-14 | 1996-09-05 | Genencor Int Europ | Verbesserung beim bleichen von pulpe |
SE465320B (sv) * | 1990-01-10 | 1991-08-26 | Korsnaes Ab | Preparat som uppvisar enzymatisk delignifieringsaktivitet, saett att framstaella detsamma och tillaempningar daerav |
US5837515A (en) * | 1990-05-16 | 1998-11-17 | Alko-Yhtiot Oy | Enzyme preparations and methods for their production |
JP2859393B2 (ja) * | 1990-07-24 | 1999-02-17 | ノボ ノルディスク アクティーゼルスカブ | セルラーゼ及びその製造法 |
DE4129739A1 (de) * | 1990-09-11 | 1992-03-12 | Sandoz Ag | Chlorfreies bleichen von papierpulpe |
JPH04240287A (ja) * | 1991-01-21 | 1992-08-27 | Kobe Steel Ltd | パルプの漂白方法 |
FI90670C (fi) * | 1991-05-02 | 1994-03-10 | Metsae Serla Oy | Paperinvalmistukseen käytettävän alkalikäsitellyn massan käsittely |
FI108800B (fi) * | 1991-05-07 | 2002-03-28 | Iogen Corp | Menetelmä ja laitteisto entsyymin käyttämiseksi paperimassan valmistuksessa ja valkaisussa |
US5785811A (en) * | 1992-11-09 | 1998-07-28 | The Mead Corporation | Process for treating lignocellulosic material with soybean peroxidase in the presence of peroxide |
US5935836A (en) * | 1994-07-29 | 1999-08-10 | Rohm Enzyme Finland Oy | Actinomadura xylanase sequences and methods of use |
US7816129B2 (en) | 1994-07-29 | 2010-10-19 | Ab Enzymes Gmbh | Production and secretion of proteins of bacterial origin in filamentous fungi |
US6300114B1 (en) | 1994-07-29 | 2001-10-09 | Rohm Enzyme Finland Oy | Sequences of xylanase and xylanase expression vectors |
US5871730A (en) * | 1994-07-29 | 1999-02-16 | Universite De Sherbrooke | Thermostable xylanase DNA, protein and methods of use |
US6824646B2 (en) | 1999-03-23 | 2004-11-30 | Oji Paper Co., Ltd. | Process for oxygen bleaching and enzyme treating lignocellulosic pulp with liquid treatment and recovery |
CA2627846C (en) * | 1999-03-23 | 2011-01-04 | Oji Paper Co., Ltd. | Process for bleaching lignocellulose pulp |
US6942754B2 (en) | 1999-03-23 | 2005-09-13 | Oji Paper Co., Ltd. | Process for producing xylooligosaccharide from lignocellulose pulp |
US9096519B2 (en) | 2013-01-10 | 2015-08-04 | California Institute Of Technology | Process for the synthesis of ketones from internal alkenes |
US9586883B2 (en) | 2013-04-19 | 2017-03-07 | California Institute Of Technology | Aldehyde-selective wacker-type oxidation of unbiased alkenes |
CN111979823A (zh) * | 2020-08-07 | 2020-11-24 | 齐鲁工业大学 | 一种硫酸盐木浆短程序ecf漂白工艺x/d-z-p(x/z-d-p) |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO1989008738A1 (en) * | 1988-03-14 | 1989-09-21 | Cultor Oy | Procedure for bleaching cellulose pulp |
EP0383999A2 (en) * | 1989-02-14 | 1990-08-29 | Enso-Gutzeit Oy | Procedure for the bleaching of pulp |
Family Cites Families (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS5468402A (en) * | 1977-11-09 | 1979-06-01 | Kogyo Gijutsuin | Property modification of biochemical pulp |
-
1989
- 1989-05-04 FI FI892151A patent/FI86896B/fi not_active Application Discontinuation
- 1989-09-18 CA CA000611771A patent/CA1339593C/en not_active Expired - Fee Related
- 1989-09-18 NO NO893716A patent/NO172355C/no not_active IP Right Cessation
- 1989-09-18 AT AT89117233T patent/ATE91518T1/de not_active IP Right Cessation
- 1989-09-18 JP JP1241666A patent/JPH02293486A/ja active Pending
- 1989-09-18 EP EP89117233A patent/EP0395792B1/en not_active Revoked
- 1989-09-18 DE DE8989117233T patent/DE68907593D1/de not_active Expired - Lifetime
- 1989-09-18 ES ES89117233T patent/ES2045320T3/es not_active Expired - Lifetime
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO1989008738A1 (en) * | 1988-03-14 | 1989-09-21 | Cultor Oy | Procedure for bleaching cellulose pulp |
EP0383999A2 (en) * | 1989-02-14 | 1990-08-29 | Enso-Gutzeit Oy | Procedure for the bleaching of pulp |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US7541175B1 (en) | 2000-12-22 | 2009-06-02 | Iogen Energy Corporation | Alkaline extraction stages comprising xylanase |
Also Published As
Publication number | Publication date |
---|---|
JPH02293486A (ja) | 1990-12-04 |
CA1339593C (en) | 1997-12-23 |
FI892151A0 (fi) | 1989-05-04 |
ES2045320T3 (es) | 1994-01-16 |
NO172355C (no) | 1993-07-07 |
FI86896B (fi) | 1992-07-15 |
NO893716D0 (no) | 1989-09-18 |
NO172355B (no) | 1993-03-29 |
EP0395792A3 (en) | 1991-01-16 |
ATE91518T1 (de) | 1993-07-15 |
DE68907593D1 (de) | 1993-08-19 |
FI892151A (fi) | 1990-11-05 |
EP0395792A2 (en) | 1990-11-07 |
NO893716L (no) | 1990-11-05 |
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WO1991015627A1 (en) | A process for the bleaching of chemical pulp |
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