EP0813629A1 - Process for producing short-fibered softwood pulps - Google Patents
Process for producing short-fibered softwood pulpsInfo
- Publication number
- EP0813629A1 EP0813629A1 EP96906140A EP96906140A EP0813629A1 EP 0813629 A1 EP0813629 A1 EP 0813629A1 EP 96906140 A EP96906140 A EP 96906140A EP 96906140 A EP96906140 A EP 96906140A EP 0813629 A1 EP0813629 A1 EP 0813629A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- activity
- exocellulosic
- enzyme preparation
- pulp
- process according
- 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.)
- Withdrawn
Links
- 238000000034 method Methods 0.000 title claims abstract description 46
- 230000008569 process Effects 0.000 title claims abstract description 42
- 239000011122 softwood Substances 0.000 title claims abstract description 23
- 239000000835 fiber Substances 0.000 claims abstract description 46
- 230000002255 enzymatic effect Effects 0.000 claims abstract description 35
- 238000004519 manufacturing process Methods 0.000 claims abstract description 19
- 238000009826 distribution Methods 0.000 claims abstract description 17
- 102000004190 Enzymes Human genes 0.000 claims description 87
- 108090000790 Enzymes Proteins 0.000 claims description 87
- 230000000694 effects Effects 0.000 claims description 75
- 238000002360 preparation method Methods 0.000 claims description 32
- 108010059892 Cellulase Proteins 0.000 claims description 15
- 239000000203 mixture Substances 0.000 claims description 15
- 238000004904 shortening Methods 0.000 claims description 13
- 230000009471 action Effects 0.000 claims description 11
- 101710112457 Exoglucanase Proteins 0.000 claims description 10
- 229940088598 enzyme Drugs 0.000 description 55
- 108010084185 Cellulases Proteins 0.000 description 15
- 102000005575 Cellulases Human genes 0.000 description 15
- 238000010009 beating Methods 0.000 description 12
- 229920001131 Pulp (paper) Polymers 0.000 description 8
- 229920002678 cellulose Polymers 0.000 description 5
- 239000001913 cellulose Substances 0.000 description 5
- 238000006243 chemical reaction Methods 0.000 description 5
- 244000005700 microbiome Species 0.000 description 5
- 229940106157 cellulase Drugs 0.000 description 4
- 230000007613 environmental effect Effects 0.000 description 4
- 230000007062 hydrolysis Effects 0.000 description 4
- 238000006460 hydrolysis reaction Methods 0.000 description 4
- 230000002195 synergetic effect Effects 0.000 description 4
- 241000894006 Bacteria Species 0.000 description 3
- 229920003043 Cellulose fiber Polymers 0.000 description 3
- 230000015556 catabolic process Effects 0.000 description 3
- 238000006731 degradation reaction Methods 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 230000009467 reduction Effects 0.000 description 3
- 241000609240 Ambelania acida Species 0.000 description 2
- 241000233866 Fungi Species 0.000 description 2
- WQZGKKKJIJFFOK-GASJEMHNSA-N Glucose Natural products OC[C@H]1OC(O)[C@H](O)[C@@H](O)[C@@H]1O WQZGKKKJIJFFOK-GASJEMHNSA-N 0.000 description 2
- 241000222355 Trametes versicolor Species 0.000 description 2
- 239000010905 bagasse Substances 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000005265 energy consumption Methods 0.000 description 2
- 230000001747 exhibiting effect Effects 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 230000001295 genetical effect Effects 0.000 description 2
- 239000008103 glucose Substances 0.000 description 2
- 239000011121 hardwood Substances 0.000 description 2
- 238000004537 pulping Methods 0.000 description 2
- 239000011541 reaction mixture Substances 0.000 description 2
- 238000003860 storage Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 235000000346 sugar Nutrition 0.000 description 2
- 150000008163 sugars Chemical class 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- 230000003313 weakening effect Effects 0.000 description 2
- UHPMCKVQTMMPCG-UHFFFAOYSA-N 5,8-dihydroxy-2-methoxy-6-methyl-7-(2-oxopropyl)naphthalene-1,4-dione Chemical compound CC1=C(CC(C)=O)C(O)=C2C(=O)C(OC)=CC(=O)C2=C1O UHPMCKVQTMMPCG-UHFFFAOYSA-N 0.000 description 1
- 241000838140 Acrophialophora fusispora Species 0.000 description 1
- 244000251953 Agaricus brunnescens Species 0.000 description 1
- 235000001674 Agaricus brunnescens Nutrition 0.000 description 1
- 241000331231 Amorphocerini gen. n. 1 DAD-2008 Species 0.000 description 1
- 241000228212 Aspergillus Species 0.000 description 1
- 241000228215 Aspergillus aculeatus Species 0.000 description 1
- 241001225321 Aspergillus fumigatus Species 0.000 description 1
- 241000228245 Aspergillus niger Species 0.000 description 1
- 241000228251 Aspergillus phoenicis Species 0.000 description 1
- 241001465318 Aspergillus terreus Species 0.000 description 1
- 241000228260 Aspergillus wentii Species 0.000 description 1
- 241001530056 Athelia rolfsii Species 0.000 description 1
- 241000193747 Bacillus firmus Species 0.000 description 1
- 241000194103 Bacillus pumilus Species 0.000 description 1
- 235000014469 Bacillus subtilis Nutrition 0.000 description 1
- 102100032487 Beta-mannosidase Human genes 0.000 description 1
- 241000193764 Brevibacillus brevis Species 0.000 description 1
- 241001545603 Cadophora malorum Species 0.000 description 1
- 241000186318 Cellulomonas biazotea Species 0.000 description 1
- 241000157920 Cellulomonas cellasea Species 0.000 description 1
- 241000186320 Cellulomonas fimi Species 0.000 description 1
- 241000186220 Cellulomonas flavigena Species 0.000 description 1
- 241000186219 Cellulomonas gelida Species 0.000 description 1
- 241000863388 Cellulomonas gilvus Species 0.000 description 1
- 241000186217 Cellulomonas uda Species 0.000 description 1
- 241000863387 Cellvibrio Species 0.000 description 1
- 241001047427 Cellvibrio fulvus Species 0.000 description 1
- 241000048484 Centruroides ochraceus Species 0.000 description 1
- 240000001817 Cereus hexagonus Species 0.000 description 1
- 241001515917 Chaetomium globosum Species 0.000 description 1
- 241000511343 Chondrostoma nasus Species 0.000 description 1
- 241000123346 Chrysosporium Species 0.000 description 1
- 241001149955 Cladosporium cladosporioides Species 0.000 description 1
- 241000002309 Collariella virescens Species 0.000 description 1
- 229920000742 Cotton Polymers 0.000 description 1
- 244000069686 Crusea rubra Species 0.000 description 1
- 241000605111 Cytophaga hutchinsonii Species 0.000 description 1
- 241000189557 Dichomitus squalens Species 0.000 description 1
- 101710121765 Endo-1,4-beta-xylanase Proteins 0.000 description 1
- 241000223218 Fusarium Species 0.000 description 1
- 241000427940 Fusarium solani Species 0.000 description 1
- 241000233732 Fusarium verticillioides Species 0.000 description 1
- 241001492300 Gloeophyllum trabeum Species 0.000 description 1
- 229920002488 Hemicellulose Polymers 0.000 description 1
- 241001210415 Herpetosiphon geysericola Species 0.000 description 1
- 241000223199 Humicola grisea Species 0.000 description 1
- 241001480714 Humicola insolens Species 0.000 description 1
- 241000222344 Irpex lacteus Species 0.000 description 1
- 244000062209 Malaxis flavescens Species 0.000 description 1
- 241001184659 Melanocarpus albomyces Species 0.000 description 1
- 241000223251 Myrothecium Species 0.000 description 1
- 241000233893 Neocallimastix frontalis Species 0.000 description 1
- 240000009215 Nepeta cataria Species 0.000 description 1
- 241000221961 Neurospora crassa Species 0.000 description 1
- 241000186218 Oerskovia turbata Species 0.000 description 1
- 241000194105 Paenibacillus polymyxa Species 0.000 description 1
- 240000006460 Panicum notatum Species 0.000 description 1
- 241000712655 Papulaspora Species 0.000 description 1
- 241000228150 Penicillium chrysogenum Species 0.000 description 1
- 241000907558 Penicillium citrioviride Species 0.000 description 1
- 241001136550 Penicillium javanicum Species 0.000 description 1
- 241000351908 Pestalotiopsis versicolor Species 0.000 description 1
- 241000222393 Phanerochaete chrysosporium Species 0.000 description 1
- 241001503951 Phoma Species 0.000 description 1
- 241000224486 Physarum polycephalum Species 0.000 description 1
- 235000007685 Pleurotus columbinus Nutrition 0.000 description 1
- 240000001462 Pleurotus ostreatus Species 0.000 description 1
- 235000001603 Pleurotus ostreatus Nutrition 0.000 description 1
- 244000158441 Pleurotus sajor caju Species 0.000 description 1
- 241000221945 Podospora Species 0.000 description 1
- 241000222640 Polyporus Species 0.000 description 1
- 241001459644 Poronia punctata Species 0.000 description 1
- 241001492489 Postia placenta Species 0.000 description 1
- 241000589540 Pseudomonas fluorescens Species 0.000 description 1
- 241000231139 Pyricularia Species 0.000 description 1
- 241000959173 Rasamsonia emersonii Species 0.000 description 1
- 241000813090 Rhizoctonia solani Species 0.000 description 1
- 241000215622 Saccobolus Species 0.000 description 1
- 241000222481 Schizophyllum commune Species 0.000 description 1
- 241000221696 Sclerotinia sclerotiorum Species 0.000 description 1
- 241000223256 Scytalidium lignicola Species 0.000 description 1
- 241001123667 Sordaria fimicola Species 0.000 description 1
- 241001660858 Sporocytophaga myxococcoides Species 0.000 description 1
- 241001085826 Sporotrichum Species 0.000 description 1
- 241001425746 Stereum sanguinolentum Species 0.000 description 1
- 241000958211 Streptomyces flavogriseus Species 0.000 description 1
- 241001136559 Talaromyces variabilis Species 0.000 description 1
- 241001516650 Talaromyces verruculosus Species 0.000 description 1
- 241000203775 Thermoactinomyces Species 0.000 description 1
- 241000228182 Thermoascus aurantiacus Species 0.000 description 1
- 241000203783 Thermomonospora curvata Species 0.000 description 1
- 241001313536 Thermothelomyces thermophila Species 0.000 description 1
- 241000006364 Torula Species 0.000 description 1
- 241000223259 Trichoderma Species 0.000 description 1
- 241000378866 Trichoderma koningii Species 0.000 description 1
- 241001304120 Trichoderma pseudokoningii Species 0.000 description 1
- 241000499912 Trichoderma reesei Species 0.000 description 1
- 241001114490 Trichurus spiralis Species 0.000 description 1
- 241001123669 Verticillium albo-atrum Species 0.000 description 1
- 240000006794 Volvariella volvacea Species 0.000 description 1
- 235000004501 Volvariella volvacea Nutrition 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 108010055059 beta-Mannosidase Proteins 0.000 description 1
- 238000004061 bleaching Methods 0.000 description 1
- 150000001720 carbohydrates Chemical class 0.000 description 1
- 235000014633 carbohydrates Nutrition 0.000 description 1
- 206010061592 cardiac fibrillation Diseases 0.000 description 1
- 239000000969 carrier Substances 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 108010037721 cytase Proteins 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000006911 enzymatic reaction Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 230000002600 fibrillogenic effect Effects 0.000 description 1
- 239000012634 fragment Substances 0.000 description 1
- 229910001385 heavy metal Inorganic materials 0.000 description 1
- 230000003301 hydrolyzing effect Effects 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 238000009533 lab test Methods 0.000 description 1
- 230000000813 microbial effect Effects 0.000 description 1
- 238000003801 milling Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000035772 mutation Effects 0.000 description 1
- 239000006187 pill Substances 0.000 description 1
- 238000011020 pilot scale process Methods 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 244000034971 purple passionvine Species 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 230000003381 solubilizing 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
- D21C9/001—Modification of pulp properties
-
- 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
Definitions
- the present invention relates to a process in accordance with the preamble of claim 1 for preparing chemical pulp.
- the present invention also relates to an enzyme composition for said use.
- Softwood pulp generally has the drawback of an unfavourable fibre length distribution. This negatively influences the formation and thus the printability and other properties of the paper and board, manufactured using said pulp.
- Traditionally a portion of hardwood pulp is added to the softwood pulp to balance the fibre length distribution.
- the use of thinning material or felling of young forests has also been contemplated, but this has sometimes unwanted effects on the total forest economy.
- the use of enzymes is well known in the pulp and paper industry.
- Xylanases are presently used as a pretreatment to facilitate bleaching.
- Cellulases are also know to be used in the processing of recycled fibre to digest fines and improve dewatering on the paper machine.
- WO 94/20667 describes an enzymatic process for pretreatment of wood raw- material which makes it possible to reduce the specific energy consumption of mechanical pulping and to improve the technical properties of the fibres.
- the inventors describe a special enzyme preparation exhibiting simultaneously both celiobiohydrolase activity and mannanase activity. Thereby the hydrolysis of insoluble cellulose is avoided and the strength properties of the fibres not impaired. Again, fibre shortening would rather be a negative effect.
- this process requires a cooler and more dilute pulp than what normally is the case in industrial pulp- and paper production. Additionally the long treatment times given in the examples suggest that very large storage volumes are necessary.
- WO 92/18688 relates to a cellulase preparation with a high content of endogluca ⁇ nase and a little or no celiobiohydrolase for use for treatment of paper pulp, inter alia to improve the drainage properties of the pulp. It is obvious that such an enzyme treatment • mainly solubilizes the fines, thus improving the dewatering. It is noted, also in this description, that the damage to the cellulose fibres in the pulp is less, because of the low celiobiohydrolase activity.
- the process and enzyme preparation according to the present invention can, of course, also be applied to unbleached chemical pulp but then the enzyme dosage and/or process conditions as treatment time, temperature and pH have to be adjusted accordingly.
- the present description will deal only with the treatment of bleached softwood pulp.
- the process and enzyme preparation according to the present invention when necessary, can be applied also to pulps including recycled fibres as well as virgin fibres and mixtures, in varying propor ⁇ tions, of the two. It has now surprisingly been shown that the simultaneous use of endo- and exocellulases in a treatment step before the beating operation results in a controlled fibre shortening in softwood pulp.
- the fibres present in the chemical pulp are always to some extent mechanically damaged, i.e. the fibres show more or less sharp kinks and bends in their three dimensio- nal structure. It has now been shown that a combination of endo- and exocellulase activity, e.g. endo- and exoglucanase activity, attacks these damaged points and causes changes in the cellulose crystal structure. Thus, local weakening of the fibre is achieved. In other words the enzymatic treatment introduces local damage, in the following called "breakage domains" on the fibres. Later, when the pulp is subjected to mechanical action in the form of beating, using conventional equipment for this purpose, the fibres break in a controlled fashion at these breakage domains.
- Figure 1 is a graphic representation showing zero-span tensile index as a function of enzymatic treatment at different enzyme dosages and temperatures
- Figure 2 is a graphic representation showing the fibre length distribution of untreated pulp compared to the fibre length distribution of pulp subjected to enzymatic treatment according to the present invention.
- the ratio of endocellulase activity to exo- cellulase activity can be varied.
- Endoglucanase can be used together with a trace amount of exocellulase and vice versa, preferably in an interval of 1 : 100 to 100: 1.
- the amount of exocellulase activity is significantly larger than the amount of endocellulase activity.
- the ratio of exocellulase to endocellulase is in the interval of about 4: 1 to 5: 1 , which gives a synergistic effect.
- An optimal ratio will depend on the actual enzymes used and their sources and this optimal ratio can easily be determined by a person skilled in the art.
- the endocellulase is preferably endoglucanase and the exocellulase is preferably exoglucanase.
- the endoglucanase and exoglucanase can be used in a clean, isolated form or as a mixture of enzymes from different sources. Also commercial enzyme mixtures exhibiting the above specified activities can be used.
- Table 2 Examples of cellulase-producing bacteria ⁇ Cellulomonas flavigena, C. biazotea, C. cellasea, C. fimi, C. gelida, C. curtae,
- fungi and bacteria listed above are only given as examples.
- microorganisms of the species Trichoderma and Aspergillus are considered specially suitable for the production of the present enzymes but the scope of the present invention is not limited to the use of the named microorganisms. It is very possible that other enzyme producing microorganisms suitable for the present invention already exist or will be developed using mutation and selection or methods of genetical engineering. It is also likely, that the enzyme producing capabilities of an existing microorganism can be further enhanced through genetical engineering.
- the environmental conditions during the enzymatic treatment are not critical for the scope of invention, but can of course be used to controll the enzymatic reaction.
- the environmental conditions of the enzymatic treatment are to a certain extent governed by the normal process parameters of the pulping and paper making processes. Simultane ⁇ ously, the requirements of the enzyme or enzyme mixture have to be considered.
- a pH in the interval of 2 - 13 is possible, while an interval of 4 - 10 is preferable, depending on the enzymes used.
- the temperature of the reaction mixture is of considerable importance as it affects the reaction rate of the enzymes. The reaction rate directly influences the time needed for the desired reaction to take place and thus the necessary storage volumes.
- the tempera ⁇ ture can be in an interval from about 5 - 95 °C, theoretically even higher e.g. about 100 °C, but preferably about 30 - 60 °C and most preferably about 45 - 50 °C.
- highly thermotolerant enzymes which would enable the enzymatic treatment to be performed at considerably higher temperatures. It is possible that this would give rise to unexpected synergistic effects.
- a skilled worker can, given the requirements of the enzymes in question, determine more exactly the optimum environmental conditions for application of the enzyme or enzyme mixture. The presence of heavy metals can also influence the en ⁇ zymatic activities and should therefore be avoided. A skilled worker with knowledge of both the manufacturing of paper and the usage of enzymes is able to adapt the process to accommodate the enzymatic treatment according to the present invention.
- the enzymatic treatment is terminated before the pulp is subjected to the beating operation.
- the enzymatic treatment is preferably terminated by adjusting the pH of the reaction mixture to an interval outside, preferably above, the functional interval of the enzyme mixture. This functional interval depends on the pH-stability of the enzyme, the temperature and other environmental conditions.
- the beating operation is modified in relation to the enzymatic treatment.
- enzymatically treated pulp requires a lower input of energy at the beating stage. It is of course of interest both to minimize the energy consumption and the production of fines during beating. A skilled worker can easily optimize the milling in relation to the enzymatic treatment.
- the enzyme or enzyme mixture used is bound to a carrier in order to facilitate its removal and possible reuse. Suitable carriers and methods for immobilization of enzymes can be found in the littera- ture.
- the present invention also relates to an enzyme composition for treatment of softwood pulp for the production of paper and board where essential product properties are obtained by controlling the fibre length distribution of the pulp, whereby said pulp is first subjected to enzymatic treatment and thereafter subjected to mechanical or equivalent actions in order to effectuate controlled fibre shortening at the breakage domains, characterized in that said enzyme preparation introduces local breakage domains on the fibres.
- said enzyme preparation exhibits both endocellulosic and exocellulosic activity.
- the ratio of endocellulosic activity to exocellulosic activity in said enzyme preparation is in the interval from 1: 100 to 100: 1. More preferably the exo- cellulosic activity is significantly larger than the endocellulosic activity and most prefe ⁇ rably the ratio of exocellulosic activity to endocellulosic activity is in the interval of about 4: 1 to 5: 1.
- the exocellulosic activity is exoglucanase activity and the endocellulosic activity is endoglucanase activity.
- ® enzyme mixture used was Celluclast from Novo Nordisk AS, Denmark, with an enzyme activity of 1500 NCU/g enzyme.
- NCU One Novo Cellulase Unit (NCU) is the amount of enzym which, under standard conditions, degrades CMC to reducing carbohydrates with a reduction power corresponding to 1 ⁇ mol glucose per minute.
- Pulp viscosity can be seen as a measure, relative to the average chain length for the cellulose.
- shape factor on the other hand is the ratio of the projected length of the fiber and its real length, thus giving an indication of the curvature or crookedness of the fibre.
Landscapes
- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Wood Science & Technology (AREA)
- Chemical & Material Sciences (AREA)
- Biochemistry (AREA)
- Microbiology (AREA)
- Paper (AREA)
Abstract
Process for utilizing softwood pulp for the production of paper and board, where essential product properties, e.g. a good print quality are obtained by controlling the fibre length distribution of the pulp through enzymatic treatment, followed by a mechanical or other equivalent treatment of the fibres.
Description
PROCESS FOR PRODUCING SHORT-FIBERED SOFTWOOD PULPS
The present invention relates to a process in accordance with the preamble of claim 1 for preparing chemical pulp. The present invention also relates to an enzyme composition for said use.
Softwood pulp generally has the drawback of an unfavourable fibre length distribution. This negatively influences the formation and thus the printability and other properties of the paper and board, manufactured using said pulp. Traditionally a portion of hardwood pulp is added to the softwood pulp to balance the fibre length distribution. The use of thinning material or felling of young forests has also been contemplated, but this has sometimes unwanted effects on the total forest economy. It is also possible to subject the softwood pulp to extensive mechanical treatment but this unevitably increases the amount of fines in the pulp, thereby negatively affecting the dewatering properties of the pulp. There is presently an apparent need for new processes to obtain a softwood pulp for making paper and board with a shorter average fiber length and a more narrow fibre length distribution. The use of enzymes is well known in the pulp and paper industry. Xylanases are presently used as a pretreatment to facilitate bleaching. Cellulases are also know to be used in the processing of recycled fibre to digest fines and improve dewatering on the paper machine.
Traditional use of enzymes in pulp- and paper applications has thus been for purposes of reduction of fines or remowal of other unwanted components. Early patent documents, e.g. US-2 280 307, describes the use of cytase for solubilizing hemicellulose. An advantage is said to be that the cellulose fibres are not affected. The process according to US 3 041 246 uses cellulases to obtain fibrillation of cotton linters without appreciable shortening of the fibres. US 2 280 307 describes enzymatic treatment of wood pulp for Ihe purpose of dissolving non-cellulosic materials while exerting only a minimum of destruc¬ tive action on the cellulosic material.
More recent documents also describe enzymatic treatment of paper pulp, e.g. CA 758 488, that describes simultaneous beating and enzymatic treatment. The enzyme is continuosly added during the beating operation and the description underlines the positive synergistic effect achieved in simultaneous beating and enzymatic treatment. This document does not contain any specific mentioning of controlled fibre shortening. Since beating is normally used with the goal to obtain strength with minimum input of energy, fibre shortening should rather be an undesired effect.
WO 94/20667 describes an enzymatic process for pretreatment of wood raw-
material which makes it possible to reduce the specific energy consumption of mechanical pulping and to improve the technical properties of the fibres. The inventors describe a special enzyme preparation exhibiting simultaneously both celiobiohydrolase activity and mannanase activity. Thereby the hydrolysis of insoluble cellulose is avoided and the strength properties of the fibres not impaired. Again, fibre shortening would rather be a negative effect. Further, according to the examples presented in the description of WO 94/20667, this process requires a cooler and more dilute pulp than what normally is the case in industrial pulp- and paper production. Additionally the long treatment times given in the examples suggest that very large storage volumes are necessary. WO 92/18688 relates to a cellulase preparation with a high content of endogluca¬ nase and a little or no celiobiohydrolase for use for treatment of paper pulp, inter alia to improve the drainage properties of the pulp. It is obvious that such an enzyme treatment • mainly solubilizes the fines, thus improving the dewatering. It is noted, also in this description, that the damage to the cellulose fibres in the pulp is less, because of the low celiobiohydrolase activity.
Other documents defining the state of the art are e.g. Evitkov et al., in Ferment. Spirit. Prom.. 4(1979) 31-34 and Ghose et al., Biotechnol. Bioeng., 1 (1979) 131-146. Both these documents concern the production of fermentable sugars of different types of fibrous waste. Ghose et al. discuss methods for hydrolyzing bagasse and conclude, that the synergistic action of exoglucanase, endoglucanase and xylananse is effective for hydrolysis of bagasse but not for pure cellulose. The above method is further directed to the production of glucose, that is a full hydrolysis of the fibres. Evitkov et al. are also driving the hydrolysis as far as possible, with the intention to produce fermentable sugars of fibrous wastes. Said documents concern an non-specific and very far reaching degradation of the fibres, and are thus not applicable to the production of paper and board, where the undisputable goal is to preserve the fibre structure.
Obviously the presently known processes for enzymatic treatment of paper pulp are not related to controlled fibre shortening in the production of paper and/or board. Known processes do not adress the same problem that the present invention intends to solve. Contrary to all conventional practices, the present inventors worked to find an enzyme preparation and to develop a treatment process that actually would cause localized damage to the cellulose fibres. The purpose was to find a way of controlling the fibre length in softwood pulp, making it usable for the production of fine paper or board with improved essential qualities, e.g. better formation and better print quality. The present in-
vention mainly concerns a process for treatment of chemical softwood pulp, preferably bleached chemical softwood pulp. The process and enzyme preparation according to the present invention can, of course, also be applied to unbleached chemical pulp but then the enzyme dosage and/or process conditions as treatment time, temperature and pH have to be adjusted accordingly. For reasons of simplification, the present description will deal only with the treatment of bleached softwood pulp. Naturally the process and enzyme preparation according to the present invention, when necessary, can be applied also to pulps including recycled fibres as well as virgin fibres and mixtures, in varying propor¬ tions, of the two. It has now surprisingly been shown that the simultaneous use of endo- and exocellulases in a treatment step before the beating operation results in a controlled fibre shortening in softwood pulp.
The fibres present in the chemical pulp are always to some extent mechanically damaged, i.e. the fibres show more or less sharp kinks and bends in their three dimensio- nal structure. It has now been shown that a combination of endo- and exocellulase activity, e.g. endo- and exoglucanase activity, attacks these damaged points and causes changes in the cellulose crystal structure. Thus, local weakening of the fibre is achieved. In other words the enzymatic treatment introduces local damage, in the following called "breakage domains" on the fibres. Later, when the pulp is subjected to mechanical action in the form of beating, using conventional equipment for this purpose, the fibres break in a controlled fashion at these breakage domains. This surprising effect results in a shorter average fiber length and a more narrow fibre length distribution of the pulp, which better corresponds to the fibre length distribution of hardwood pulp. This in turn is favourable in the production of paper and board, e.g. the production of printing papers. Normally, con- ventional beating of softwood pulp, without previous enzymatic treatment, results in a fibre length distribution with a large content of very short fibre fragments, so called fines, and a substantial amount of unnecessarily long fibres. This unfavourable fibre length dis¬ tribution causes irregularities in the paper and reduces for example the print quality. Con¬ trolled fibre shortening according to the present invention for the first time makes it possible to use softwood pulp alone for the production of high quality printing papers.
The invention is further illustrated in the following preferred embodiments, examples and figures, wherein
Figure 1 is a graphic representation showing zero-span tensile index as a function of enzymatic treatment at different enzyme dosages and temperatures,
Figure 2 is a graphic representation showing the fibre length distribution of untreated pulp compared to the fibre length distribution of pulp subjected to enzymatic treatment according to the present invention.
The extent of fibre shortening can be controlled through several means. Firstly, according to one embodiment of the invention, the ratio of endocellulase activity to exo- cellulase activity can be varied. Endoglucanase can be used together with a trace amount of exocellulase and vice versa, preferably in an interval of 1 : 100 to 100: 1. More preferably, the amount of exocellulase activity is significantly larger than the amount of endocellulase activity. Most preferably the ratio of exocellulase to endocellulase is in the interval of about 4: 1 to 5: 1 , which gives a synergistic effect. An optimal ratio will depend on the actual enzymes used and their sources and this optimal ratio can easily be determined by a person skilled in the art.
According to the present invention the endocellulase is preferably endoglucanase and the exocellulase is preferably exoglucanase. The endoglucanase and exoglucanase can be used in a clean, isolated form or as a mixture of enzymes from different sources. Also commercial enzyme mixtures exhibiting the above specified activities can be used. One
® example of such a commercially available product is Celluclast 1 ,5L from Novo Nordisk
A/S. Obviously also other commercial or independently developed enzyme products can be available to a person skilled in the art. Several endo- and exoglucanases are known and can be used according to the present invention. Microbial enzymes are preferred for economical reasons. The enzymes should be active and stable at the conditions, especially the pH and temperature, that prevail during the pulp treating processes. Examples of suitable enzymes are those derived from the microorganisms listed in Table 1 and Table 2. Table 1 : Examples of cellulase-producing fungi
Agaricus bisporus
Ascoboulus furfuraceus
Aspergillus aculeatus, A. fumigatus," A. niger, A. phoenicis, A. terreus and A. wentii Botryodiploida theobromae
Chaetomium cellulolyticum, C. globosum and C. thermophile
Chrysosporium lignorum
Cladosporium cladosporioides
Coriolus versicolor Dichomitus squalens
Eupenicillium javanicum
Fo es famentarium
Fusarium moniliforme, F. solani and Fusarium spp.
Table 1. continued
Humicola grisea and H. insolens
Hypocapra merdaria Irpex lacteus
Lenzites trabea
Mycellophtora thermophila
Myriococcum albomyces
Myrothecium verrucarla Neocallimastix frontalis
Neurospora crassa
Paecilomyces fusisporus and P. variotly
Papulaspora thermophilia
Pellicularia filamentosa Penicillium chrysogenum, P. citrioviride, P. funicolosum, P. notatum,
P. pinophilium, P. variabile and P. verruculosum
Pestalotiopsis versicolor
Phanerochaete chrysosporium
Phialophora malorum Phoma hibernica
Physarum polycephalum
Pleurotus ostreatus and P. sajor-caju
Podospora deciplens
Polyporus schweinitzil and P. versicolor Poria placenta
Poronia punctata
Pyricularia orzyzae
Saccobolus trunctatus
Schizophyllum commune Sclerotinia libertiana
Sclerotium rolfsii
Scytalidium lignicola
Sordaria fimicola
Sporotrichum pulverulentum and S. thermophile Stereum sanguinolentum
Talaromyces emersonii
Thermoascus aurantiacus
Thrausiotheca clavata
Torula thermophile Trichoderma koningii, T. pseudokoningii and T. reesei
Trichurus spiralis
Verticillium albo-atrum
Volvariella volvacea
Table 2: Examples of cellulase-producing bacteria ^ Cellulomonas flavigena, C. biazotea, C. cellasea, C. fimi, C. gelida, C. curtae,
C. uda and C. turbata Bacillus brevis, B. firmus, B. lichenformis, B. pumilus, B. subtilis, B. polymyxa and B. cereus Serrata marcescens
Table 2. continued
'Pseudomonas fluorescens var. cellulosa'
'Cellvibrio viridus, C. flavescens, C. ochraceus, C. fulvus, C. vulgaris and C. gilvus'
Cytophaga hutchinsonii, C. aurantiaca, C. rubra, C. tenulssima, C. winogradskii and C. krzemienlewskoe Herpetosiphon geysericolus Sporocytophaga myxococcoides Streptomyces flavogriseus
'Thermoactinomyces spJ Thermomonospora curvata
(1 The bacteria within prime signs are not validly classified.
The fungi and bacteria listed above are only given as examples. Presently microorganisms of the species Trichoderma and Aspergillus are considered specially suitable for the production of the present enzymes but the scope of the present invention is not limited to the use of the named microorganisms. It is very possible that other enzyme producing microorganisms suitable for the present invention already exist or will be developed using mutation and selection or methods of genetical engineering. It is also likely, that the enzyme producing capabilites of an existing microorganism can be further enhanced through genetical engineering.
The environmental conditions during the enzymatic treatment are not critical for the scope of invention, but can of course be used to controll the enzymatic reaction. The environmental conditions of the enzymatic treatment are to a certain extent governed by the normal process parameters of the pulping and paper making processes. Simultane¬ ously, the requirements of the enzyme or enzyme mixture have to be considered. A pH in the interval of 2 - 13 is possible, while an interval of 4 - 10 is preferable, depending on the enzymes used. The temperature of the reaction mixture is of considerable importance as it affects the reaction rate of the enzymes. The reaction rate directly influences the time needed for the desired reaction to take place and thus the necessary storage volumes. Depending on the enzymes used, their thermotolerance and thermal optimum, the tempera¬ ture can be in an interval from about 5 - 95 °C, theoretically even higher e.g. about 100 °C, but preferably about 30 - 60 °C and most preferably about 45 - 50 °C. One can anticipate a future development of highly thermotolerant enzymes, which would enable the enzymatic treatment to be performed at considerably higher temperatures. It is possible that this would give rise to unexpected synergistic effects.
A skilled worker can, given the requirements of the enzymes in question,
determine more exactly the optimum environmental conditions for application of the enzyme or enzyme mixture. The presence of heavy metals can also influence the en¬ zymatic activities and should therefore be avoided. A skilled worker with knowledge of both the manufacturing of paper and the usage of enzymes is able to adapt the process to accommodate the enzymatic treatment according to the present invention.
According to one embodiment of the present invention the enzymatic treatment is terminated before the pulp is subjected to the beating operation. The enzymatic treatment is preferably terminated by adjusting the pH of the reaction mixture to an interval outside, preferably above, the functional interval of the enzyme mixture. This functional interval depends on the pH-stability of the enzyme, the temperature and other environmental
® factors. Using the commercially available enzyme product Celluclast the pH -was adjusted to about pH 8 to terminate the reaction.
According to another embodiment of the invention the beating operation is modified in relation to the enzymatic treatment. Generally, enzymatically treated pulp requires a lower input of energy at the beating stage. It is of course of interest both to minimize the energy consumption and the production of fines during beating. A skilled worker can easily optimize the milling in relation to the enzymatic treatment.
According to one embodiment of the invention, only part of the flow of chemical pulp is subjected to enzymatic treatment and then returned to the main flow. According to another embodiment of the invention, the enzyme or enzyme mixture used is bound to a carrier in order to facilitate its removal and possible reuse. Suitable carriers and methods for immobilization of enzymes can be found in the littera- ture.
The present invention also relates to an enzyme composition for treatment of softwood pulp for the production of paper and board where essential product properties are obtained by controlling the fibre length distribution of the pulp, whereby said pulp is first subjected to enzymatic treatment and thereafter subjected to mechanical or equivalent actions in order to effectuate controlled fibre shortening at the breakage domains, characterized in that said enzyme preparation introduces local breakage domains on the fibres.
According to an embodiment of the invention said enzyme preparation exhibits both endocellulosic and exocellulosic activity.
Preferably the ratio of endocellulosic activity to exocellulosic activity in said enzyme preparation is in the interval from 1: 100 to 100: 1. More preferably the exo-
cellulosic activity is significantly larger than the endocellulosic activity and most prefe¬ rably the ratio of exocellulosic activity to endocellulosic activity is in the interval of about 4: 1 to 5: 1.
According to a preferable embodiment of the invention the exocellulosic activity is exoglucanase activity and the endocellulosic activity is endoglucanase activity.
The invention is further described in the following examples which are not in any way intended to limit the scope of the invention set forth in the claims.
Example 1
Laboratory scale experiments were performed to determine the influence of enzymatic treatment on zero-span tensile index. Two series of experiments- w h increasing enzyme concentrations were performed, one at a temperature of 40 °C and the other at a temperature of 50 °C. The treatment time at both temperatures was 2 hours. The
® enzyme mixture used was Celluclast from Novo Nordisk AS, Denmark, with an enzyme activity of 1500 NCU/g enzyme. (One Novo Cellulase Unit (NCU) is the amount of enzym which, under standard conditions, degrades CMC to reducing carbohydrates with a reduction power corresponding to 1 μmol glucose per minute.) The results are presented in Table 3 and graphically in Fig. 1.
Table 3: Zero-span tensile index (Nm/g)
Dosage (NCU/ 10 g pulp) 2 h / 40 °C 2 h / 50 °C
0 118 1 18
25 87 45
50 75 26 *
70 51 23 *
100 46 19 *
The accuracy of reading was low for these values.
It can be clearly seen that the effect depends on both dosage and treatment temperature. With an increase in temperature the same effect can be achieved with a significantly lower enzyme dosage. An increase from 40°C to 50°C allows for a reduction of the necessary enzyme dosage from 100 to 25 NCU/ 10 g pulp while maintaining the same result.
Example 2
The ability of the enzymatic treatment to accomplish the desired narrowing of the fiber length distribution was tested in pilot scale experiments. Enzymatic treatment was performed in batches of 400 kg pulp over night. The pH of the pulp was adjusted to 5,0 -
5,5 by addition of H SO4 during disintegration, whereafter the enzyme mixture (Cel-
® luclast from Novo Nordisk AS, Denmark, enzyme activity 1500 NCU/g enzyme) was added to the pulp. Two different enzyme concentrations were used. The enzyme dosages were determined on the basis of previous laboratory experiments and were 7,5 NCU/ 10 g pulp and 18,75 NCU/10 g pulp, respectively. After 13 hours, the reaction was stopped by adjusting the pH to 8,0 - 8,2 by addition of NaOH-pills to the mixture. Subsequently the pulp was beaten in an industrial Disc-refiner at a concentration of 3,5 %. For an overview of the experimental conditions, see Table 4.
Table 4: The experimental conditions
Control Batch 1 Batch 2
Initial pH 5,0 - 5,5 5,0 - 5,5 5,0 - 5,5
Enzyme addition - 7,5 U/10 g pulp 18,75 U/10 g pulp
Treatment time 13 h 13 h 13 h
Temperature 38 - 40 °C 38 - 40 °C 38 - 40 °C
Fibre concentration 3,5 % 3,5 % 3,5 %
Stopping pH 8,0 - 8,2 8,0 - 8,2 8,0 - 8,2
Changes in fibre strength after the enzymatic treatment was observed by measu¬ ring zero-span tensile index on dry and rewetted sheets. Additionally pulp viscosity and shape factor (also known as "curl index") was determined. Pulp viscosity can be seen as a measure, relative to the average chain length for the cellulose. The shape factor on the other hand is the ratio of the projected length of the fiber and its real length, thus giving an indication of the curvature or crookedness of the fibre.
It was seen from the results that a stronger enzymatical treatment caused stronger degradation of the cellulose. This was obvious from the viscosity and zero-span tensile index. The strongest effect was observed for rewetted zero-span tensile index. That the
difference between dry and rewetted zero-span results increased along with increasing enzyme dosage indicates that the degradation took place as local weakening of the fibre, in the form of local breakage domains as discussed previously. The shape factor remained unchanged in Batch 1. In Batch 2, which was subjected to a relatively high enzyme concentration, the fibre deformations have also increased. The average fibre length was not influenced by the enzymatic treatment alone. The results are summarized in Table 5.
Table 5. Changes in fibre properties
Control Batch 1 Batch 2
Pulp viscosity 818 739 677
Zero-span tensile 131 116 101 index, dry (Nm/g)
Zero-span tensile 116 77 47 index, rewetted (Nm/g)
Fibre length (mm) 2,24 2,09 2,22
Form factor (%) 86,7 86,4 85,2
The fibre length distribution after enzymatic treatment and subsequent beating is presented graphically in Fig. 2. The graphs clearly demonstrate the beneficial effect the process according to the present invention has on the fibre length distribution.
Although the invention has been described with regard to its preferred em¬ bodiments, which constitute the best mode presently known to the inventors, it should be understood that various changes and modifications as would be obvious to one having the ordinary skill in this art may be made without departing from the scope of the invention which is set forth in the claims appended hereto.
Claims
1. Process for utilizing softwood pulp for the production of paper and board where essential product properties are obtained by controlling the fibre length distribution of the pulp, characterized in that said pulp is first subjected to enzymatic treatment introducing local breakage domains on the fibres and thereafter subjected to mechanical or other equivalent actions in order to effectuate controlled fibre shortening at said breakage domains.
2. Process according to claim 1, characterized in that the enzymatic action is terminated before the mechanical action.
3. Process according to claim 1 or 2, characterized in that ..he en¬ zymatic action is stopped by a pH-change, preferably by increasing the pH to a level above the functional interval of the enzyme.
4. Process according to claims 1-3, characterized in that the enzyme treatment consists of subjecting the softwood pulp to an enzyme preparation, which exhibits both endocellulosic and exocellulosic activity.
5. Process according to claim 4, characterized in that the ratio of endocellulosic activity to exocellulosic activity is in the interval from 1:100 to 100:1.
6. Process according to claim 4, characterized in that the exocellulosic activity is significantly larger than the endocellulosic activity.
7. Process according to claim 4, characterized in that the ratio of exocellulosic activity to endocellulosic activity is in the interval of about 4:1 to 5:1.
8. Process according to any of the previous claims, characterized in that the exocellulosic activity is exoglucanase activity and the endocellulosic activity is endoglucanase activity.
9. Process according to any of the previous claims, characterized in that only a portion of the total pulp is diverted from a main flow, subjected to enzymatic treatment, and returned to the main flow.
10. Process according to any of the previous claims, characterized in that the softwood pulp includes recycled fibres.
11. Process according to any of the previous claims, characterized in that the enzyme or enzyme mixture used is bound to a carrier in order to facilitate its removal and possible reuse.
12. Enzyme preparation for treatment of softwood pulp for the production of
paper and board where essential product properties are obtained by controlling the fibre length distribution of the pulp, whereby said pulp is first subjected to enzymatic treatment and thereafter subjected to mechanical or equivalent actions in order to effectuate control¬ led fibre shortening at the breakage domains, characterized in that said enzyme preparation introduces local breakage domains on the fibres.
13. Enzyme preparation according to claim 12, characterized in that said enzyme preparation exhibits both endocellulosic and exocellulosic activity.
14. Enzyme preparation according to claim 13, characterized in that the ratio of endocellulosic activity to exocellulosic activity in said enzyme preparation is in the interval from 1:100 to 100:1.
15. Enzyme preparation according to claim 13, characterized in that said enzyme preparation the exocellulosic activity is significantly larger than the endo¬ cellulosic activity.
16. Enzyme preparation according to claim 13, characterized in that the ratio of exocellulosic activity to endocellulosic activity is in the interval of about 4: 1 to
5:1.
17. Enzyme preparation according to claim 13, characterized in that in said enzyme preparation the exocellulosic activity is exoglucanase activity and the endo¬ cellulosic activity is endoglucanase activity.
AMENDED CLAIMS
[received by the International Bureau on 30 July 1996 (30.07.96); original claims 1 and 12 amended; remaining claims unchanged (2 pages)]
1. Process for utilizing softwood pulp in the production of paper and board where essential product properties are obtained by controlling the fibre length distribution of the pulp, characterized in that said pulp is first subjected to enzymatic treatment introducing local breakage domains on the fibres and thereafter subjected to mechanical or other equivalent actions in order to effectuate controlled fibre shortening at said breakage domains.
2. Process according to claim 1, characterized in that the enzymatic action is terminated before the mechanical action. 3. Process according to claim 1 or 2, characterized in that the en¬ zymatic action is stopped by a pH-change, preferably by increasing the pH to a level above the functional interval of the enzyme.
4. Process according to claims 1-3, characterized in that the enzyme treatment consists of subjecting the softwood pulp to an enzyme preparation, which exhibits both endocellulosic and exocellulosic activity.
5. Process according to claim 4, characterized in that the ratio of endocellulosic activity to exocellulosic activity is in the interval from 1:100 to 100:1.
6. Process according to claim 4, characterized in that the exocellulosic activity is significantly larger than the endocellulosic activity. 7. Process according to claim 4, characterized in that the ratio of exocellulosic activity to endocellulosic activity is in the interval of about 4:1 to 5:1.
8. Process according to any of the previous claims, characterized in that the exocellulosic activity is exoglucanase activity and the endocellulosic activity is endoglucanase activity. 9. Process according to any of the previous claims, characterized in that only a portion of the total pulp is diverted from a main flow, subjected to enzymatic treatment, and returned to the main flow.
10. Process according to any of the previous claims, characterized in that the softwood pulp includes recycled fibres. 11. Process according to any of the previous claims, characterized in that the enzyme or enzyme mixture used is bound to a carrier in order to facilitate its removal and possible reuse.
12. Enzyme preparation for the manufacture of a composition for the treatment of softwood pulp in the production of paper and board where essential product properties are obtained by controlling the fibre length distribution of the pulp, whereby said pulp is first subjected to enzymatic treatment and thereafter subjected to mechanical or equivalent actions in order to effectuate controlled fibre shortening at the breakage domains, characterized in that said enzyme preparation introduces local breakage domains on the fibres.
13. Enzyme preparation according to claim 12, characterized in that said enzyme preparation exhibits both endocellulosic and exocellulosic activity. 14. Enzyme preparation according to claim 13, characterized in that the ratio of endocellulosic activity to exocellulosic activity in said enzyme preparation is in the interval from 1:100 to 100:1.
15. Enzyme preparation according to claim 13, characterized in that said enzyme preparation the exocellulosic activity is significantly larger than the endo- cellulosic activity.
16. Enzyme preparation according to claim 13, characterized in that the ratio of exocellulosic activity to endocellulosic activity is in the interval of about 4: 1 to 5:1.
17. Enzyme preparation according to claim 13, characterized in that in said enzyme preparation the exocellulosic activity is exoglucanase activity and the endo¬ cellulosic activity is endoglucanase activity.
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
SE9500846A SE506440C2 (en) | 1995-03-09 | 1995-03-09 | Control of softwood fiber length distribution by enzymatic and mechanical treatment |
SE9500846 | 1995-03-09 | ||
PCT/SE1996/000284 WO1996028606A1 (en) | 1995-03-09 | 1996-03-04 | Process for producing short-fibered softwood pulps |
Publications (1)
Publication Number | Publication Date |
---|---|
EP0813629A1 true EP0813629A1 (en) | 1997-12-29 |
Family
ID=20397492
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP96906140A Withdrawn EP0813629A1 (en) | 1995-03-09 | 1996-03-04 | Process for producing short-fibered softwood pulps |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP0813629A1 (en) |
SE (1) | SE506440C2 (en) |
WO (1) | WO1996028606A1 (en) |
Families Citing this family (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6146494A (en) * | 1997-06-12 | 2000-11-14 | The Procter & Gamble Company | Modified cellulosic fibers and fibrous webs containing these fibers |
FR2965570B1 (en) * | 2010-09-30 | 2012-11-02 | Arjo Wiggins Fine Papers Ltd | METHOD FOR THE ENZYMATIC REFINING OF A PAPER PULP COMPRISING CELLULOSIC FIBERS TO REDUCE THEIR LENGTH |
US9145640B2 (en) | 2013-01-31 | 2015-09-29 | University Of New Brunswick | Enzymatic treatment of wood chips |
US9127401B2 (en) | 2013-01-31 | 2015-09-08 | University Of New Brunswick | Wood pulp treatment |
FI126698B (en) | 2013-12-18 | 2017-04-13 | Teknologian Tutkimuskeskus Vtt Oy | A process for making fibrillated cellulosic material |
Family Cites Families (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CA758488A (en) * | 1967-05-09 | C. Jenness Lyle | Process for treating paper pulp | |
DK73891D0 (en) * | 1991-04-22 | 1991-04-22 | Novo Nordisk As | ENZYME TREATMENT |
-
1995
- 1995-03-09 SE SE9500846A patent/SE506440C2/en not_active IP Right Cessation
-
1996
- 1996-03-04 WO PCT/SE1996/000284 patent/WO1996028606A1/en not_active Application Discontinuation
- 1996-03-04 EP EP96906140A patent/EP0813629A1/en not_active Withdrawn
Non-Patent Citations (1)
Title |
---|
See references of WO9628606A1 * |
Also Published As
Publication number | Publication date |
---|---|
WO1996028606A1 (en) | 1996-09-19 |
SE506440C2 (en) | 1997-12-15 |
SE9500846D0 (en) | 1995-03-09 |
SE9500846L (en) | 1996-10-31 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
Oksanen et al. | The effect of Trichoderma reesei cellulases and hemicellulases on the paper technical properties of never-dried bleached kraft pulp | |
Khandeparkar et al. | Application of thermoalkalophilic xylanase from Arthrobacter sp. MTCC 5214 in biobleaching of kraft pulp | |
Pala et al. | Enzymatic upgrade of old paperboard containers | |
US20090107643A1 (en) | Method For Mechanical Pulp Production | |
US10570562B2 (en) | Methods for reducing content of hexenuronic acids in cellulosic pulp | |
FI81394B (en) | FOERFARANDE FOER BEHANDLING AV MASSA MED ENZYMER. | |
Desai et al. | Biodeinking of old newspaper pulp using a cellulase-free xylanase preparation of Aspergillus niger DX-23 | |
CA2457785C (en) | Enzymatic treatment of pulp to increase strength using truncated hydrolytic enzymes | |
Chapla et al. | Assessment of a thermostable xylanase from Paenibacillus sp. ASCD2 for application in prebleaching of eucalyptus kraft pulp | |
Nathan et al. | Low Molecular Weight Xylanase from Trichoderma viride VKF3 for Bio-bleaching of Newspaper Pulp. | |
AU2002259075A1 (en) | Enzymatic treatment of pulp to increase strength | |
Sango et al. | Partial purification of bacterial cellulo-xylanolytic enzymes and their application in deinking of photocopier waste paper | |
EP0524220B1 (en) | A pulping process using cellulase | |
Kaur et al. | Application of microbial enzymes in dissolving pulp production | |
CA2541229C (en) | Modified method for mechanical pulp production | |
WO2002022943A1 (en) | Method of deinking waste paper by using cellulase without lowering paper strength and method of evaluating the same | |
EP0813629A1 (en) | Process for producing short-fibered softwood pulps | |
Rashmi et al. | Enzymatic refining of pulps: an overview | |
Wu et al. | Comparative characterization of a recombinant Volvariella volvacea endoglucanase I (EG1) with its truncated catalytic core (EG1-CM), and their impact on the bio-treatment of cellulose-based fabrics | |
Rashmi et al. | Enzymatic treatment of secondary fibres for improving drainage: An overview | |
Ozer et al. | Distinctive delignification with consecutive application of Geobacillus sp. 71 xylanase and Rhodococcus jostii rha1 lignin peroxidase | |
Spiridon et al. | Enzymatic hydrolysis of Pinus pinaster kraft pulp | |
Viikari et al. | Cellulases in pulp and paper processing | |
Pawlak | Biochemical additives for papermaking | |
VIIKARI | J. BUCHERT, T. OKSANEN, J. PERE, M. SIIKA-AHO, A. SUURNÄKKI and |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
Free format text: ORIGINAL CODE: 0009012 |
|
17P | Request for examination filed |
Effective date: 19971009 |
|
AK | Designated contracting states |
Kind code of ref document: A1 Designated state(s): AT DK FI FR SE |
|
17Q | First examination report despatched |
Effective date: 20010502 |
|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN |
|
18D | Application deemed to be withdrawn |
Effective date: 20011113 |