Classifications

• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21B—FIBROUS RAW MATERIALS OR THEIR MECHANICAL TREATMENT
  • D21B1/00—Fibrous raw materials or their mechanical treatment
  • D21B1/02—Pretreatment of the raw materials by chemical or physical means
  • D21B1/021—Pretreatment of the raw materials by chemical or physical means by chemical means

Definitions

• the present invention relates to a method in accordance with the preamble of Claim 1 for preparing mechanical pulp.
• Patent Specification EP 0429 422 suggests the use of laccase treatments in mechanical pulping between the first and the second refining treatments. This specification states that the laccase treatment decreases the energy consumption of the refining process.
• the Patent Specification WO 93/23606 suggests a treatment with phenol oxidase enzymes after the last refining or grinding treatments. The said treatment had no effect on the energy consumption of the refining treatment but it has been said to have an influence on the strength of paper or board.
• Patent Specification WO 94/20667 suggests that an enzyme preparation be used for the same purpose, containing cellobiohydrolase activity and mannanase activity.
• the examples of the said specifications deal with rough wood, such as the long-fibre fraction of fractioned TMP spruce pulp, once-refined TMP spruce pulps (with freeness values of CSF 450 - 550) or TMP pulps refined to different freeness levels (30 - 300).
• a synergistically acting cellulase enzyme product i.e., cellulase
• cellulase a synergistically acting cellulase enzyme product
• the treatment resulted in the hydrolysis of the insoluble cellulose and, thus, in the weakening of the strength properties of the pulp.
• Patent Specification US 6,267,841 describes a manufacturing method of thermo-mechanical pulp, wherein the pulp is treated with enzyme between the first and the second refining processes. It also suggests the treatment of chips with enzymes before the first refining.
• the specification cites enzymes, such as pectinase, xylanase, laccase, cellulase or the mixtures thereof. The specification gives no numerical values of any energy savings obtained.
• the different enzymatic treatments according to prior art have been applied to raw wood material, which has been defibred to a certain extent already during the manufacturing process.
• the enzymatic treatment is not as effective when applied to chips directly, because it is difficult to make the enzyme preparation to be effectively absorbed into the fibres of a raw material that is in the form of chips.
• the surface area of the raw wood material is not sufficient for an effective enzymatic treatment to take place.
• Grethlein, H.E. Biotechnology, February 1985, pp. 155 to 160 are too small to receive any enzyme molecules.
• the pulping liquor is made to penetrate the chips used in pulp cooking by treating the chips with pressure shocks in the presence of the pulping liquor.
• the chips are treated in the presence of the cooking liquor by varying the pressure from a pressure of 4.5 kp/cm 2 and a treatment time of 10 - 16s to a pressure of 2 kp/cm 2 and a treatment time of 5 - 6s, the treatment being repeated 6 - 8 times at 1-minute intervals /Rydholm, 1965).
• the Patent Specification WO 95/09267 suggests treating the chips, which are used in pulp cooking, with a chemical solution by subjecting the chips to a vacuum and making the chemical solution penetrate the wood fibres by means of a pressure shock.
• the chemical solution can be cooking liquor that contains, for example, catalysts and enzymes.
• the object of the invention is, thus, to be able to decrease the amount of lignin in order to diminish the need of decreasing the residue lignin at the final stage of cooking.
• the application does not describe in detail, whether or not the enzymes penetrate the wood cells successfully and whether or not the enzymes have any effect on the decrease of the amount of lignin.
• the US Patent 5,374,555 suggests the removal of lignin from the lignocellulose material by means of a protease enzyme.
• the patent suggests a mechanical treatment of chips, for example, in a screw clamp.
• the patent specification reminds that cellulase can be used as a pre-treatment enzyme for the chips or the pulp, but it does not suggest carrying out a treatment with cellulase in connection with the mechanical processes.
• the purpose of the patent is not to save energy but to remove lignin, and there are no observations relating to energy economy. While the application suggests a protease treatment of the wood material, which is used both in the manufacture of mechanical pulp and in that of chemical pulp, the main issue is the removal of lignin as a pre-treatment in the manufacture of chemical pulp.
• the Patent Specification WO 97/40194 suggests changing the structure or the composition of the wood by adding to the compressed chips fungal or bacterial cultures or products, such as enzymes obtained from them, by means of pressure.
• the purpose of the compression is to make cracks and fractures in the wood.
• microbes of their products, while the chips expand are absorbed by the structures of the wood partially by the virtue of under pressure, partially by the capillary action.
• the application suggests, among others, fungi from the genera Ceriposiophsis, Phanerochaete and Ophiostoma.
• enzymes lipolytic, proteolytic, linginolytic, cellulolytic and hemicellulolytic enzymes are mentioned.
• the patent specification describes the absorption of the enzyme preparation Clariant Cartazyme HSTM (xylanase) into the compressed chips after releasing the pressure. Liquid was removed after the treatment, and mechanical pulp was prepared from the chips. In that case, the amount of energy consumed was 7.5% less than in the case of chips that were treated with a buffer only.
• the enzyme preparations Clariant Cartazyme NSTM (xylanase) and Sigma porcine pancreas Lipase L-3126 were treated. In that case, the amount of energy consumed was 12.5% less than when treated with a buffer only.
• the highest energy savings were made by combining enzyme preparations originating in different sources, of which the amount of a lipase of a mammalian origin, in particular, was considerable.
• the amount of the other enzymes used was also fairly high, which makes one suspect that the energy savings achieved were not particularly cost-effective.
• the purpose of the present invention is to remove at least some disadvantages of prior art and to provide an improved method for the manufacture of mechanical pulp.
• the object of the invention is to provide a pre-treatment method of chips to be used before preparing the mechanical pulp.
• chips can be pre-treated with an enzyme preparation that has synergistically acting enzyme activities.
• the enzyme preparation does not need to contain any certain isolated enzyme activity only, but an enzyme preparation containing different enzyme activities can be used directly as the enzyme preparation.
• the treatment according to the method can be applied to the chips directly. As the enzymatic treatment takes place at an early stage of the pulping process, savings in the refining energy are then as high as possible.
• the chips are pre-treated with an enzyme that is capable of degrading the structural parts of the wood, after which mechanical pulp is manufactured from the chips by refining. It is preferable to carry out the enzymatic treatment by compressing the chips and by bringing the compressed chips in a liquid phase into contact with the enzyme composition to absorb the enzyme composition into the chips.
• the enzyme composition contains both cellobiohydrolase and endoglucanase. It is particular for the composition to contain an effective amount of both cellobiohydrolase and endoglucanase.
• the amount of endoglucanase compared with that of cellobiohydrolase is higher than what is naturally produced by the industrial production strains of cellulase, such as Trichoderma, in their growth media.
• the method according to the invention is mainly characterized in that which is presented in the characterizing part of Claim 1.
• the invention provides several considerable advantages. When using the methods according to the preferable embodiments of the invention, considerably lower amounts of energy are consumed than in the methods according to prior art. The energy saving can be as much as 20% compared with a method, wherein the chips are not treated with the enzyme preparation.
• the strength of the pulp was not weakened; on the contrary, it improved to some extent.
• the optical properties also remained good.
• the enzyme preparation is produced in a host organism, which excretes the enzyme preparation out of the cell, whereby the enzyme preparation does not need to be isolated from the cell. It is also especially advantageous to use a genetically modified organism as the production host, producing the desired enzyme preparation directly in the growth medium. This provides the considerable advantage that the used enzyme activity does not need to be isolated from the host organism or its growth medium but, for example, the growth medium of the host organism can be directly used.
• the enzymes that participate in the modification and degradation of cellulose are commonly called "cellulases”. These enzymes include endo- ⁇ -glucanases, cellobiohydrolases and ⁇ -glucosidase. Countless organisms, such as various wood rotting fungi, moulds and anaerobic bacteria are able to produce some or all of these enzymes. Depending on the type of organism and cultivation conditions, these enzymes are produced extracellularly in various ratios and amounts.
• enzyme preparation refers to any product that contains at least one enzyme or a structural part of the enzyme. Accordingly, the enzyme preparation can be, for example, a growth medium containing the enzyme(s), an isolated enzyme or a mixture of two or more enzymes. "Cellulase” or “cellulase enzyme preparation”, in turn, refers to an enzyme preparation containing at least one of the above-mentioned cellulase enzymes.
• the "enzyme composition” in this application means the same as the enzyme preparation.
• the enzyme preparation or the enzyme composition may also contain, for example, buffers, stabilizers, preservatives or other necessary additives.
• the "cellobiohydrolase activity" in this application refers to an activity that is capable of modifying the crystalline parts of the cellulose.
• the cellobiohydrolase I and II I activities refer to the main activities of the cellobiohydrolase produced by Trichoderma or to the corresponding activities produced by some other organism.
• the endoglucanase activity in this application refers to an activity capable of modifying the amorphous parts of the cellulose.
• the endoglucanase I and the endoglucanase II activities refer to the main activities of the endoglucanase produced by Trichoderma or to the corresponding activities produced by another organism.
• An enzyme preparation containing "an effective amount" of cellobiohydrolase and endoglucanase refers to an enzyme preparation, in which the effect of each enzyme on the chips can be measured as a reduction in the energy consumption of the refining.
• the effective amount of cellobiohydrolase and endoglucanase provides a decrease of at least 3%, preferably at least 5%, more preferably at least 8%, most preferably at least 10% in the energy consumption of the refining.
• the method according to the invention can be combined with treatments carried out with other enzymes, such as hemicellulases (e.g., xylanases, glucuronidases and mannanases) or esterases.
• enzymes such as hemicellulases (e.g., xylanases, glucuronidases and mannanases) or esterases.
• additional enzyme preparations containing ⁇ -glucosidase activity can be used in the present processes, because this kind of ⁇ -glucosidase activity prevents the end product inhibition caused by cellobiose.
• Cellobiohydrolase and endoglucanase enzyme preparations are produced by growing suitable micro-organism strains, known to produce cellulase.
• the strains are preferably production strains that are used industrially.
• the growth medium used can be, for example, a simple cellulosic substrate (1% Solka floc), which the necessary trace elements have been added to (Mandels and Weber, 1969).
• the production strains can be bacteria, fungi or moulds.
• the micro-organisms belonging to the following families can be mentioned:
• the desired host may be the Trichoderma mould ( EP 244 234, Mitsuishi et al., 1990 ), yeast (Penttilä et al., 1988), some other mould, from families such as Aspergillus (van den Hondel et al., 1992), a bacterium or any other micro-organism, whose genetics are sufficiently well-known.
• the desired cellobiohydrolase and endoglucanase are produced by means of the mould strain Trichoderma, preferably the strain T . reesei.
• the said strain is a generally used production organism and its cellulases are fairly well known.
• T . reesei synthesizes two cellobiohydrolases, which are later referred to as CBH I and CBH II, several endoglucanases, of which EGI and EGII are the main activities, and at least two ⁇ -glucosidases (Chen et al, 1992).
• Endoglucanases are typically active on soluble and amorphous substrates (CMC, HEC, ⁇ -glucan), whereas the cellobiohydrolases are able to hydrolyze crystalline cellulose.
• the cellobiohydrolases act clearly synergistically on crystalline cellulose, but their hydrolysis mechanisms are supposed to be different from each other.
• the present knowledge of the hydrolysis mechanisms of cellulases is based on results obtained on pure cellulase preparations, and may not be valid in cases, where the substrate also contains other components, such as lignin or hemicellulose.
• T . reesei cellobiohydrolases and endoglucanases
• T . reesei do not essentially differ from each other with respect to their optimal external conditions, such as pH or temperature. Instead, they differ from each other with respect to their ability to hydrolyze and modify cellulose in the raw wood material.
• the cellobiohydrolases I and II also differ to some extent from each other, and so do the endoglucanases I and II. In the preferred embodiments of this invention, however, it seems that the ratio of the cellobiohydrolases to the endoglucanases is more important than the interrelation between the various cellobiohydrolases or the various endoglucanases.
• Trichoderma reesei naturally produces various cellulase components in its growth medium, the amount and the interrelation of them depending on the production strain and the external conditions used.
• the following relative amounts of the main cellulases have been proposed: CBH I 60%, CBH II 20%, EG I 10% and EG II 10% (St ⁇ hlberg, 1991). In that case, the ratio of the cellobiohydrolases to the endoglucanases is about 4:1.
• the preferred enzyme mixtures for the method according to the invention included those containing both cellobiohydrolase enzymes and endoglucanase enzymes. While not wanting to commit our to any theories, it very strongly seems that the method according to the invention needs both cellobiohydrolase enzymes and endoglucanase enzymes, because the endoglucanase is capable of preparing, in the chips, objects that the cellobiohydrolase is able to act on. As neither activity alone is able to provide the desired effect, the cellobiohydrolases and the endoglucanases must work in synergy.
• the ratio of the cellobiohydrolases to the endoglucanases is 3:1 - 1:3, most preferably 2:1 - 1:2, and even more preferably about 1:1.
• the most preferable cellulase compositions are those, wherein the weight ratio of the cellobiohydrolases and the endoglucanases is close to 1:1.
• an energy saving effect can even be provided by a weight ratio deviating from this, if the endoglucanase used has a very strong activity so that even a small amount is sufficient to provide the desired effect.
• the preferred embodiments of the invention also include an enzyme preparation, wherein the portion of endoglucanases in the preparation is 2 - 60% by weight. Even more preferred is a preparation, wherein the portion of endoglucanases in the preparation is 20-55% by weight and the most preferred is one, wherein the portion of endoglucanases is 45 - 50% by weight.
• an amount of endoglucanases can be reached by increasing the amount of either EGI or EGII, or both, in the preparation. If the amount of EGI is increased exclusively, the amount of EGI in the preparation should reach a level of 15 - 45% by weight. This is also true, if only the amount of EGII is increased.
• US Patent No. 5,874,293 describes an enzyme preparation that is produced by the strain Trichoderma (ALKO 3529) that overproduces EGII.
• the ratio of CBH:EG in the growth medium produced by the strain is estimated to be 1 - 1.4:1. It would be advantageous to use the growth medium produced by such a strain, for example, in the present invention.
• the publication Karhunen et al. (1993) describes a Trichoderma host that is modified to overproduce the EGI enzyme. The growth medium of this host could also be used in the present invention.
• preferable enzyme mixtures according to the preferred embodiments of this invention include those, wherein the amount of endoglucanase is higher than what the cellulase-producing micro-organisms, such as Trichoderma, especially T . reesei, would naturally produce in their growth media.
• the modified cellulase preparation herein refers to a preparation, wherein the ratio of CBH and EG components has been changed by methods that are well-known to average experts. Such methods include, e.g., the genetic modification of a host organism so that the host organism produces a novel cellulase compound in its growth medium. Other viable methods of manufacturing modified cellulase preparations include the fractioning of a cellulase-containing growth medium or combining different cellulase mixtures.
• the host organism can be modified genetically to produce the desired cellobiohydrolases and endoglucanases in a desired proportion.
• the genetic modification of the strains of the family Trichoderma can be carried out by the methods described in the patent EP 244234 or in the publication Suominen et al., 1993.
• Preferable enzyme preparations to be used in the embodiments of this invention include those, wherein the mould T. reesei is modified to overproduce EG I and/or EG II enzymes.
• the overproduction host may also have been modified so as to produce less of some cellobiohydrolase activities, especially the CBH I or CBH II activities, if any, or to produce less endoglucanases, if any, especially the EG I and/or EG II activities.
• cellobiohydrolase activities especially the CBH I or CBH II activities, if any, or to produce less endoglucanases, if any, especially the EG I and/or EG II activities.
• there should be cellobiohydrolase activities therefore, adding endoglucanase activities to the enzyme preparations is more advantageous than decreasing cellobiohydrolase activities or removing the endoglucanases.
• Corresponding enzyme preparations can also be manufactured by purifying suitable cellobiohydrolase and endoglucanase enzymes and combining the same in advantageous proportions, or by adding to an enzyme preparation, which is produced by a non-modified host, the desired enzyme activities, for example, the EGI and EGII activities.
• the strains which are capable of overproducing EGI and EGII enzymes, can be constructed, for example, by transferring genes coding for these enzymes (egl1 Penttilä et al. 1986 and egl2 Saloheimo et al. 1988) to a selected Trichoderma host as several copies or to replace some genes of Trichoderma, such as the cbh1 and cbh2 genes that code for cellobiohydrolases, as described in the publication Suominen et al. (1993).
• the said genes can be expressed under a strong cbh1 promoter, as described in the publication Paloheimo et al. (1993).
• the T . reesei strain QM6a can be used as a host, especially the strains QM9414 and Rut C - 30, which are developed from the same for the production of cellulase, or strains developed from them, which produce less protease.
• the enzyme preparation is manufactured by means of a host organism, which is modified to produce cellobiohydrolases and endoglucanases in a desired proportion in its growth medium.
• a host organism which is modified to produce cellobiohydrolases and endoglucanases in a desired proportion in its growth medium.
• endoglucanase I and/or II enzymes are added to a growth medium, which is produced by a non-modified host organism that naturally produces cellulases in its growth medium, the enzymes having either been produced by a micro-organism that is modified to overproduce these enzymes, or isolated and possibly purified from the growth medium.
• the above-mentioned methods can also be combined.
• the cellobiohydrolase and the endoglucanase can be separated from the growth medium of the production host by means of several known methods.
• various purifying techniques are combined, such as precipitation, ion exchange chromatographic and affinity chromatographic as well as gel chromatographic methods.
• the enzyme preparations can be manufactured by means of the mould Trichoderma or some other production host. Genes that code for cellobiohydrolase and endoglucanase can originate in Trichoderma or some other host that produces the preferable cellobiohydrolase and endoglucanase activities; and the said activities in the enzyme preparation can be from the same or a different origin.
• the treatment according to the present invention is applied to chips.
• the raw wood material is chipped in a normal manner so that the chip length is about 15-25 mm.
• the chips can be graded by removing oversize and too thick chips and fines.
• the chip material is typically compressed by at least 10%, generally 10 - 30% of its original bulk volume.
• the chips are compresses in a ratio of 1:2 - 1:10.
• a ratio of compression of at least 1:4 is preferably used.
• the compression treatment is preferably carried out by a method, wherein the chips are compressed without a considerable circular motion, because the object is not to crush the pieces of chips but make microscopic cracks in the raw wood material.
• the compression can be implemented by various means, e.g., in a screw clamp or by a hydraulic press.
• the impregnated chips are treated for a sufficient time in conditions favourable for the activity of the enzyme, after which the chips are processed in a normal manner before refining, including pre-heating with steam before feeding them into the refiner.
• the method according to the invention is not limited to a certain raw wood material but can generally be applied to both softwood and hardwood, such as the species of the Pinaceae order (e.g., the Picea and Pinus families), the species of the Salicaceae order (e.g., the Populus family) and the species in the Betula family.
• the species of the Pinaceae order e.g., the Picea and Pinus families
• the species of the Salicaceae order e.g., the Populus family
• Betula family e.g., the species in the Betula family.
• the compressed chips are brought into contact with the enzyme preparation in a liquid phase. This is best carried out so that the chips are compressed in an enzyme solution.
• the proportion of the liquid and the chips is preferably selected so that the liquid is able to effectively act on the chips.
• the proportion of liquid to the chips can be 10:1 - 2:1, and it is preferably 6 - 8:1.
• the compression pressure can be 10 - 20 MPa, and it is preferably 12 - 15 MPa.
• the duration of the compression/absorption stage should be at least 1 min; the duration is preferably 5 - 100 min and generally 10 - 30 min. After releasing the compression, the chips are allowed to return to their original volume under the enzyme solution, whereby the enzyme solution is impregnated into the chips.
• the pH and the temperature of the enzyme solution should be suitable for the functioning of the enzyme preparation.
• the pH should preferably be within a range of pH 3 - 10, preferably pH 4 - 8, and the temperature should be 20 - 55°C, preferably 30 - 45°C.
• the chips are treated for a sufficiently long time in the conditions mentioned above.
• the treatment time greatly varies depending on the properties (size, thickness) of the chips, sort of wood, compression treatment, enzyme preparation, operational conditions etc., and a suitable treatment time must be specified for each case separately. In terms of costs, as short a time as possible is advantageous but in terms of process technology, there are no obstacles for a treatment of several hours.
• the treatment time can be within a range of 1 - 24h, preferably 1 - 12h.
• the amount of enzyme preparation used in the invention in the treatment of chips is selected so that the amount of free sugars released in the solution is preferably about 0.1 - 1.0% of the original dry matter.
• a suitable dosage, determined as total protein, is 0.1 - 7mg of protein per g of chips, preferably 3 - 6mg of protein per g of chips (as dry matter).
• mechanical pulp is manufactured by refining chips that are treated with an enzyme to obtain a drainability value, which is preferably at least 100ml CSF, more preferably 40 - 80ml CSF.
• a drainability value which is preferably at least 100ml CSF, more preferably 40 - 80ml CSF.
• the enzymatic treatment according to the present invention is advantageous, when combined with the manufacture of mechanical pulp by the refining method, in particular, and when refining the pulp into drainability of 100 CSF or lower.
• the invention provides considerable advantages. Accordingly, it can be used to considerably reduce the specific energy consumption of refining; in accordance with the preferred embodiments of the invention, as much as 20% lower energy consumption can be achieved than with untreated source materials, as the examples below indicate.
• a suitable enzyme preparation By means of a suitable enzyme preparation, the properties of the mass can also be improved.
• a high yield is obtained in the manufacture of mechanical pulp by refining, the quality of the pulp is good, the strengths are maintained, the optical properties are good, and the method is easy to connect to the present processes.
• the invention can be applied to all manufacturing methods of mechanical pulp, such as the manufacture of thermo-mechanical pulp (TMP) and refined mechanical pulp (RMP).
• TMP thermo-mechanical pulp
• RMP refined mechanical pulp
• Enzymatic treatments with a cellulase mixture were carried out on sorted spruce sapwood chips ( ⁇ 7mm), using an enzyme dosage of 6.3mg of protein per g of chips (as dry matter), [KL1][KL2]a commercial enzyme preparation produced by the Trichoderma strain, wherein the weight proportions of CBH:EG were defined as 1:1.
• a compression treatment was exerted on the chips using a PREX hydraulic press. In the hydraulic compression, a chip lot (200g) was compressed in the enzyme solution into a volume that was about 20% smaller than the original, using a compression load of 48t (14 Mpa). The ratio of liquid to wood was 11:4 and the duration of the compression/absorption stage was 10min.
• the chips After releasing the compression, the chips were allowed to return to their original volume under the enzyme solution, whereby the enzyme solution was impregnated into the chips. As a reference, an otherwise similar treatment was used, but without the enzyme. In the compression treatment, neither visual nor microscopic changes were perceived in the chips.
• the chips (+ the compression solution) were transferred into a rotary air oven for further processing. The treatment was carried out in atmospheric pressure and at a temperature of 45°C. The amount of carbohydrates released in the treatment solution, as reducing sugars, was defined after 6 and 22 h. The result obtained was compared with a treatment, wherein the compression treatment of chips was omitted. The results are shown in Table 1.
• the effects of the combined compression/absorption and enzymatic treatments on the beatability of the chips were examined by means of a blade refiner.
• the equipment used in the tests contained the actual refiner and an accurate energy measuring system connected thereto.
• the refiner chamber of the blade refiner consisted of a cylinder provided with counter blades (20 in number) and a rotary rotor having four wing-like blades.
• Several refining operations (125g dry matter per refining) were carried out for each specific energy consumption curve (SEC) by varying the refining time (3 - 12min) and, thus, also the energy level of the refining.
• the total energy consumption of the refining was obtained from a watt-hour meter by means of a cumulative pulse counter.
• the energy consumption value obtained per amount of defibred chips was corrected by a zero load.
• the defibration times for the treated spruce sapwood chips were 3 - 12min.
• the treatments were carried out as described in Example 3 (45°C, 22h).
• the compression/absorption treatments were carried out using a treated cellulase mixture, as in Example 1, CBH I, and an EG-rich enzyme preparation.
• the dosages for the treated mixture were 0.63 and 6.3 of protein per g of chips (as dry matter).
• the dosage for CBH I and the EG-rich enzymes was 5.0mg of protein per g of chips (dry matter).
• Reference refining operations were carried out on untreated chips and chips that were treated otherwise similarly to the others but without the enzyme (a buffer treatment). After refining, the pulp was removed from the refiner, filtered, homogenized and its dry content was defined, on the basis of which the SEC value could be calculated (kWh/kg).
• the chips were impregnated and treated with a cellulase mixture (a dosage containing 0.63mg of protein per g of chips (dry matter), 45°C, 22h), as described in Example 1. After this, the chips were refined by the blade refiner in accordance with Example 2. Laboratory sheets were prepared from the refined pulps and tested in accordance with SCAN methods. The sheet properties are shown in Table 3. Table 3.
• the cellulase treatment which was applied to the chips, improved the strength properties of the pulp; the tensile strength and the z-strength (Scott Bond) in particular. Also the optical properties were well-preserved.

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• 2003
  • 2003-12-11 FI FI20031818A patent/FI20031818A/fi not_active Application Discontinuation
• 2004
  • 2004-12-13 DE DE602004022332T patent/DE602004022332D1/de active Active
  • 2004-12-13 EP EP04805154A patent/EP1699974B1/en not_active Not-in-force
  • 2004-12-13 US US10/582,525 patent/US20070151683A1/en not_active Abandoned
  • 2004-12-13 AT AT04805154T patent/ATE437993T1/de active
  • 2004-12-13 WO PCT/FI2004/000759 patent/WO2005056915A1/en active Application Filing
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