Classifications

• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21G—CALENDERS; ACCESSORIES FOR PAPER-MAKING MACHINES
  • D21G3/00—Doctors
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
  • D21F1/00—Wet end of machines for making continuous webs of paper
  • D21F1/32—Washing wire-cloths or felts
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
  • D21F7/00—Other details of machines for making continuous webs of paper

Definitions

• the invention relates to a method in a paper machine in connection with a moving element, such as cylinder, roll, felt, or wire, which is in contact with the paper web to be produced under conditions in which the moving element is exposed to substances in the paper web that can adhere to the moving element and to impair its operation in the process of paper production.
• a moving element such as cylinder, roll, felt, or wire
• a paper machine comprises a number of moving elements which come in contact with the paper web at different stages of the process of paper production in a way that substances are released from the paper web in an uncontrolled manner and tend to adhere to the moving element.
• Such substances include wood components, coatings, such as latices, starch and carboxymethyl cellulose (CMC). When these substances adhere to a moving element, they will, in the long run, cause problems at said stage in the process of paper manufacturing and can, at their worst, cause a break of the paper web.
• the problem is staining, which reduces the operability of the process and causes a need for cleaning. Furthermore, substances released from the paper web and adhering to the drying wire reduce the drying capacity when the drying wire is stained. Particularly difficult problems are caused in the press section of the paper machine, where the paper web is released from the center roll of the press section. At this time, the paper web is in the process of paper production for the first time in a situation where the paper web runs, without support, from the center roll of the press section to the draw roll. If the draw ratio must be raised due to the retaining force directed to the paper web by the adhering substances, the paper web is thus exposed to an exponentially increasing load.
• the method according to the invention is primarily characterized in that a composition comprising at least one enzyme is applied to the moving element, wherein said at least one enzyme in the composition is adapted to act by a chemical process on at least one substance, which is released from the paper web and adheres to the moving element, for the purpose of releasing and/or decomposing said at least one adhering substance from the moving element to maintain and/or improve the reliability of the moving element in the process of paper production.
• the invention relates to the surprising finding that it is possible to apply an enzyme, effective on a substance which is released from the paper web and adheres to the moving element, in a way that the enzyme is transferred to the moving element and is able to act on the substance present in the moving element by such a chemical process which eliminates the adhering effect, wherein said substance, in a decomposed or modified form, can be removed from connection with the moving element.
• the adhering substances can be influenced separately.
• a suitable enzyme composition can be selected from widely known enzymes based on their mechanisms of action for each type of adhering substance to at- tain the purpose mentioned above.
• the adhering substance consists of one or several substances from the following group: wood components, such as cellulose, hemicellu ⁇ lose, pectin, extractives, protein, lignin or lignans, coatings such as la ⁇ tices, starch and carboxymethyl cellulose (CMC), and that at least one enzyme is selected for the substance to be applied on the basis of the type of the substance adhered or possibly adhering to the moving element.
• Figure 1 is a schematic side view of an arrangement according to the invention in the press section of a paper machine
• Figure 2 is a schematic enlarged partial view of point I in Fig. 1 .
• Figure 3 shows the results of a test run according to Example 5 graphically.
• a fluid composition is sprayed on the outer surface of the center roll 1 by means of a nozzle construc ⁇ tion 4 or the like.
• This composition contains at least one enzyme which is selected according to the basic idea of the invention. This at least one enzyme acts on the colloid film-like layer on the outer surface of the center roll 1.
• the enzyme penetrates said colloid layer and causes in said colloid layer a chemical reaction according to the invention, sub ⁇ stantially thinning or even totally removing said colloid film-like layer being formed on the outer surface of the center roll 1 , released from the paper web 6 and adhered on the outer surface of the center roll 1.
• the composition sprayed on the outer surface of the center roll 1 can natu ⁇ rally contain also chemicals acting on the macroscopic layers which are removed by using the doctor blade.
• the point of applying can be placed also after the doctor blade 3, because the time of action required by the enzyme corresponds to the duration of several revolutions, and the distance between the point of applying and the doctor blade is not sig- nificant in this respect.
• Figure 2 shows schematically, by broken lines 5, the effect to be achieved by the method according to the invention, whereby the clean ⁇ ing of the surface of the center roll 1 leads to the fact that the adher- ence of the paper web 6 on the outer surface of the center roll 1 can be substantially reduced, and the paper web is released from the outer surface of the center roll closer to the ideal tangential situation.
• This earlier release of the paper web 6 can be utilized either by reducing the draw ratio, i.e. the difference of peripheral speeds between the center roll 1 and the draw roll 7, whereby the tension of the paper web is sub ⁇ stantially reduced and thus the risk of break of the paper web is re ⁇ cuted, and/or by increasing the running speed of the paper machine while maintaining the same draw ratio as without enzyme treatment.
• the draw ratio i.e. the difference of peripheral speeds between the center roll 1 and the draw roll 7
• the corresponding action can also be achieved in less critical moving elements in the process of paper production, such as in wires, felts etc., whereby a composition comprising an enzyme applied on said moving elements is carried with the moving element and generates the desired chemical reaction whereby the moving element is cleaned, maintaining its operability. It is also obvious that the enzyme can be brought in contact with the moving element in any suitable way applicable in paper machines. The enzyme can also be recovered and recycled in the process.
• enzymes which contribute to the degradation or modification of substances adhering to a moving element, such as the center rolM , the cylinder, the felt, the wire, etc., and improve the runnability of the process of paper production, e.g. the release of the paper web from the center roll in the press section.
• Enzymes degrading and modifying cellulose such as endo ⁇ glucanases, cellobiohydrolases and ⁇ -glucosidases.
• Enzymes degrading and modifying wood hemicellulose polymers such as xylan, mannan and arabinogalactan, in ⁇ cluding xylanases, mannanases, ⁇ -xylosidases, ⁇ -manno- sidases and enzymes degrading side groups of the above ⁇ mentioned polymers.
• Pectinase enzymes degrading wood pectin polymers. Proteases degrading wood proteins. Oxido-reductase enzymes acting on wood lignin and lignans, including peroxidases and phenol oxidases, particu- larly laccases, used alone or in combination with low-mo ⁇ lecular organic or inorganic cofactors and mediators. Enzymes degrading starch, such as amylases.
• Laboratory sheets were prepared from deinked pulp (DIP) and thermomechanical pulp (TMP) mixture:
• the sheet was pressed against the surface of a Valrok press roll material, generally known in the field of paper production, in two phases under a pressure of 2.2 MPa, with an exchange of the drying sheet in between.
• the pressing times were 1 min each.
• the enzyme mixture used was an enzyme available under the trademark PERGALASE A40.
• Pergalase A40 is an enzyme mixture manufactured by Genencor International, containing cellulase and hemicellulase enzymes of Trichoderma reesei which can hydrolyze colloid carbohydrates on the surface of the center roll.
• the Pergalase A40 product contains about 2700 cellulase units per millilitre.
• the de ⁇ termination of cellulase activity is based on the enzymatic hydrolysis of carboxymethyl cellulose (CMC) in 0.05 M sodium acetate buffer at 50°C and at pH 4.8.
• One activity unit refers to the quantity of enzyme which releases one micromol of reducing sugars, calculated as glu- cose, from the substrate in one minute. Reducing sugars are deter ⁇ mined by means of dinitrosalicylic acid (DNS).
• DNS dinitrosalicylic acid
• the enzyme treatment was conducted by keeping the surface of the Valrok roll for 1.0 h in a solution containing 1.0 % of Pergalase A40 en ⁇ zyme at a temperature of 50° C.
• This example shows the effects of various enzyme preparations on the releasing properties of paper web. All enzyme preparations are commercial, except Pseudomonas lipase, which was produced and recovered by the methods described in WO 95/30744 and U.S. Patent 5,445,949 and used in a concentration of 100 DLL) U/ml.
• the DLU lipase activity is determined spectrophotometrically at 550 nm as the amount of resorufin formed in the hydrolysis of 1 ,2 — 0 dilayryl-rac- glycero-3-glutaric acid resorufin ester at pH 6.8 and 37°C (See for example, WO 95/30744).
• Resinase A2X® is a lipase produced by Novo Nordisk with a standardized activity of 100 KLU/g.
• Pectinex 3XL® is a pectinase produced by Novo Nordisk with Aspergillus niger and has a standardized activity of 3000 FDU/ml.
• the enzyme treatments were carried out in a manner corresponding to that in Example 1.
• the laboratory sheets were prepared from the DIP/TMP mixture as in Example 1 , except that no filler was used and only five sheets were prepared prior to enzyme treatment. For all enzyme liquids, a dosage of 1 % was used. Results of the treatments:
• Pergalase A40® improved most efficiently the release of paper web, corresponding to about 38 % reduction in the releasing tension.
• the two lipases showed the greatest reduction of releasing tension at pH 5 and with slightly less efficiency at pH 7.
• the pectinase showed a moderate releasing effect.
• This example shows the effects of cellulase/hemicellulase and lipase enzymes on the release of paper web from press roll surface material, when the paper sheets were prepared from the furnish from a paper machine producing SC paper of 56 g/m2 basis weight. 1 % enzyme solutions were used in the treatments at pH 5. The paper sheets were prepared and the measurements were carried out in a manner corresponding to that in example 3.
• the enzymes reduced the releasing tension to about the extent as with the pulp mixtures containing DIP. Surprisingly, the two enzymes when applied together gave the highest degree of reduction of the force needed to release the paper web from the Valrok surface. The releasing tension was as much as 56 % Iower after the enzyme treatment. Futhermore, the treatment also appeared to decrease the speed of new deposit formation on the surface.
• This example shows the test runs carried out in pilot scale in a test apparatus corresponding substantially to the press section shown in Fig. 1.
• the aim was to find out the effect of Pergalase A40® enzyme on the center roll of the press section in a paper machine and how said Pergalase A40® enzyme acts on the release of the paper web from the center roll.
• the main dimensions of the test apparatus and the process conditions were the following: roll diameter 1230 mm, nip load 120 kN/m, roll material Valrok, roll speed 22 m/s.
• the temperature of the system was 47°C and the pH value 4.3.
• the furnish in the test run was SC paper furnish, i.e. the process in ⁇ volved was the production of magazine printing paper.
• a reference run R was conducted at the first stage of the test run, and it took 3 hours.
• the feed dosage of the enzyme mixture during the test run was 2 l/ton of paper.
• the appended Table 1 and Figure 3 show the effect of both the refer- ence run R and the actual test run K, i.e. the application of the enzyme, at the point of release of the paper web from the center roll. It must be noted that the draw difference was kept constant, i.e. in a numerical value of 0.49 m/s, during both the reference run R and the actual test run K, i.e. the application of the enzyme.
• the enzyme mixture was added to and mixed in raw water and sprayed on the surface of the center roll via nozzles placed after the doctor blade, after which there was a second doctor blade.
• the table shows that the point A in Fig. 2, i.e. the point of release of the paper web in the initial situation, during the reference run R, shifted for about 2 cm (transition S, A ⁇ B, Fig. 2) in a direction opposite to the di ⁇ rection of rotation of the center roll.
• the ash percent and the grammage were substantially constant during the test run.
• the test run shows cleariy that the application of Pergalase A40® en ⁇ zyme in water to be sprayed on the surface of the center roll caused a transition S of the point of release of the paper web (Fig. 2), which is significant.
• Figure 2 further illustrates the transition, point A indicating the initial situation, that is, that during the reference run, and point B in- dicating the effect of the enzyme, that is, the transition.
• the actual test run K also shows that the enzyme started to act in about one hour from the start of the application.
• Test part 1 water + conventional releasing chemical
• test run K i.e. Pergalase A40®, dose 0.2 l/ton of paper, water quantity as in references A and B Test part 3. pure water, i.e. reference B
• test part 2 The reference for the test part 2 at the beginning of the test run was the test part 1 and at the end of the test run test parts 3 (2 hours) and 4.
• Test part Draw differ ⁇ ence, %
• This example describes a mill trial carried out at a paper machine which is producing newsprint from thermomechanical and deinked pulp.
• the release of the paper web was studied at the 4th press nip after the center press roll.
• the purpose of the trial was to improve the release with the use of enzyme.
• the enzyme was applied in a manner similar to that described in Fig. 1.
• For the trial a mixture of cellulase and lipase enzymes was produced.
• the enzyme contained the following activities:
• Enzyme period Cellulase-lipase mixture, dosage 0J8 l/t
• the draw difference between the 4th press nip and drying section was 13.1 m/min during the reference period. 15 minutes after the addition of enzyme had started, the release point of the paper web started to change and during the next two hours it was clearly visible that the release angle was smaller than before enzyme addition. Four hours after the start of the enzyme addition, the draw difference was reduced to 12.2 m/min, which corresponds to about 7 % reduction. The enzyme caused no negative effects on paper quality or wet-end chemistry.
• This example describes a mill trial in order to study the release of the chemical pulp web from the two press rolls in the pulp drying machine.
• the release has been especially difficult with pulps containing high amounts of extractives and hemicelluloses.
• a release chemical a surface active agent diluted with water is used at both press rolls. The chemical and the enzyme was added to the top of the press, forming a Iiquid layer in front of the doctor blade. Conditions in the test run:
• cellulase 2488 CMC U/ml lipase: 407 DLU U/ml
• the enzyme was applied to the two press rolls in the following dosages:
• the release of the pulp web using the enzymes was equal to that using the surface active agent at day 1 and day 2.
• the reduction of the dosage to 0.08 l/t at both press rolls caused a significantly increased adhesion of the pulp web to the second press.
• 15 minutes after changing the enzyme dosage back to the level of 0.24 l/t level at the second press the release improved back to the same level as at day 1 and day 2.
• no breaks occured at the press section whereas during a reference run with the current chemical the number of breaks at the press section was normally about 1 — 2 per a three day run. It can be concluded that enzymes can also be used to improve the release of pulp web.

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• 1995
  • 1995-09-18 FI FI954377A patent/FI954377A/sv unknown
• 1996
  • 1996-09-18 BR BR9610555A patent/BR9610555A/pt not_active Application Discontinuation
  • 1996-09-18 JP JP9512415A patent/JPH11513441A/ja not_active Withdrawn
  • 1996-09-18 NZ NZ318419A patent/NZ318419A/en unknown
  • 1996-09-18 KR KR1019980701944A patent/KR19990044688A/ko not_active Application Discontinuation
  • 1996-09-18 WO PCT/FI1996/000493 patent/WO1997011225A1/en not_active Application Discontinuation
  • 1996-09-18 CA CA002229422A patent/CA2229422A1/en not_active Abandoned
  • 1996-09-18 EP EP96931078A patent/EP0868568A2/en not_active Withdrawn
  • 1996-09-18 AU AU69898/96A patent/AU702824B2/en not_active Ceased

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