Classifications

• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H21/00—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties
  • D21H21/06—Paper forming aids
  • D21H21/10—Retention agents or drainage improvers
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H11/00—Pulp or paper, comprising cellulose or lignocellulose fibres of natural origin only
  • D21H11/14—Secondary fibres
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
  • D21H17/005—Microorganisms or enzymes
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
  • D21H17/20—Macromolecular organic compounds
  • D21H17/21—Macromolecular organic compounds of natural origin; Derivatives thereof
  • D21H17/22—Proteins

Definitions

• This invention relates to improvements in treating pulp and process water in paper mills and in particular to a drainage aid for use in recycled paper mills
• Enzyme treatment of paper pulps has been proposed to improve the freeness and physical properties of paper pulps with some claiming success with recycled fibre as well as virgin fibre .
• the enzymes that have been proposed are xylanases, cellulases, and other hemicellulases. These are commercially available as crude mixtures characterised by the dominant presence of the named enzyme.
• One defect of these treatments is that careful regulation of the addition and treatment conditions is required, because excessive treatment can lead to a decline in drainage.
• Another difficulty is that paper pulps are usually neutral and many cellulases are active in the acidic pH range.
• U S A patent 4923565 proposed the use of a cellulase (having cellulase and xylanase activity), as a drainage aid for recycled paper pulp.
• One shortcoming of this proposal is that the pH must be adjusted to within the range 3 to 7.
• Patent specification WO 91/17243 discloses that a cellulase having an endo - glucanase component active between pH 6 and 10 can be used as a drainage aid for paper pulps including waste paper pulp.
• the purpose of the enzyme is to reduce harshness or clarify colour in cellulose containing fabrics
• recycled paper is intended to cover paper pulp, which includes a major portion of paper or paperboard that has been recycled.
• the present invention provides, as a drainage aid for improving the free drainage of recycled paper pulp slurries, a preparation containing a major portion of a starch hydrolysing enzyme, preferably an amylase and more preferably an alpha-amylase.
• a starch hydrolysing enzyme preferably an amylase and more preferably an alpha-amylase.
• the invention also includes a method of improving drainage of recycled paper pulp which includes the step of adding to the pulp a drainage aid containing a major portion of a starch hydrolysing enzyme, preferably amylase, prior to the separation of the water from the pulp.
• the drainage aid is added in an amount of at least 0.05% by weight of oven dried paper forming the pulp, for a time and at a temperature sufficient to produce an improved drainage rate and at a pH at which the enzymes are active.
• the addition of enzyme will improve drainage to the extent that the paper machine speed and production can be increased by about 5% or more
• this invention is predicated on the discovery that drainage of recycled paper pulps is hampered by coatings on solid components in the pulp, particularly by the fine particles in the pulp
• a significant proportion of recycled paper contains starch or starch based materials and in part this invention is based on the realisation that that enzymatic treatment may remove this coating
• This invention is also founded on the discovery that amylase is able to act on the coatings of particles in the pulp regardless of its inner composition which is not the case with previously proposed enzymes such as cellulase. It is thought that the coatings are starch based and cellulases have little effect on the starch, but are more likely to act on the particles which are primarily cellulose This further discovery also indicates that amylase is specific in its action on the starch components.
• a drainage aid having a major amylase component may be due to the coatings on the fines being largely composed of starch and thus more susceptible to amylase or other starch hydrolysing enzyme treatment. Because the amylase has Little action on the cellulose component of the fibres, excess treatment is unlikely to cause any deleterious effect. This contrasts with the prior art enzymes which are primarily cellulases which are usually recommended for papers made with a high content of virgin fibre
• amylase is a major component of the drainage aid
• other enzymes particularly cellulases active in the neutral- alkaline pH range, particularly pH 6 to 9 may be present.
• Some cellulases do improve drainage which is inhibited by cellulose based materials in the pulp and part of drainage inhibition in recycled pulps may be reduced with cellulases
• a mixture of amylase and cellulase may provide the optimum improvement Detailed description of the invention
• Process conditions for dewatering paper pulp using the drainage aid of this invention are typically: temperature 40 to 90 °C pH 6 to 9 enzyme dosage 2.5xl0 6 to 15xl0 6 IU of activity per tonne of pulp which for an alpha amylase such as BAN 240L is equivalent to 0.5 to 3 Kg per oven dried tonne of recycled paper. contact times 15 to 120 minutes
• the International Unit [I U] of enzyme activity is the amount of enzyme necessary to produce 1 micromole of reducing sugar product per minute.
• the enzymes used in the drainage aid can comprise an amylase alone preferably a crude amylase or an amylase in combination with a cellulase such as endoglucanase, xylanase, or other hemi cellulases such as mannanase, all of which are preferably active in the neutral to alkahne pH range of 6 to 9.
• a preferred crude alpha- amylase is that derived from Bacillus subtilis.
• Starch hydrolysing enzymes from other microbial species may also be used including B.licheniformis and Aspergillus oryzae
• the conventional polymeric fiocculants such as cationic polyacrylamide, which also aid in drainage can be used.
• the amylase presence will allow a reduction in the amount of the fiocculants required.
• amylase acts on the surface of all the components in the backwater regardless of inner composition, by removing starch coatings on both fines and fibres. Excessive treatment with cellulases tends to increase the fines leading to a decline in drainage performance and paper strength.
• the large surface area and particulate nature of the fines is regarded as the major contributor to poor drainage performance of recycled pulps.
• the interaction between particle surface, retention and drainage aids and water is thought to be enhanced. This consequently encourages better drainage in the forming section of the paper plant.
• Example 2 A mill trial was conducted on a twin wire fourdrinier machine producing hners and medium for corrugated boxes.
• the machine is capable of producing between 12 and 15 tons of paper per hour from furnish consisting of mixed waste paper, newsprint and OCC.
• the enzyme selected for the mill trial was BAN 240L which is an alpha amylase preparation produced by Novo Nordisk. It is a clear brown watery liquid obtained from a purified culture of Bacillus subtilis variety amyloliquefaciens.
• the enzyme addition commenced from 9am on day 1 and ceased 12pm on day 3 [approximately 48hours].
• the enzyme was dosed at 30 1 hr [as received basis] in at two points in the stock preparation area.
• Table 5 shows the mill performance over 7 days with the enzyme addition occurring on days 1 to 3. During the period of enzyme addition the machine speed increased by 4.49% compared to the operation without enzyme addition. In the table production rates have been extrapolated to remove lost time. Product output increased 6.5% but when adjusted for trim the increase was 4.48%.
• Control particle count decreased from 212056 to 144617 while the a- Amylase particle count decreased from 178404 to 128787.
• alpha-Amylase is inactivated in the drying section • alpha-Amylase is a food grade enzyme and is safe for use in making food packaging
• alpha-Amylase is commonly available

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• 1996
  • 1996-04-03 AU AUPN9096A patent/AUPN909696A0/en not_active Abandoned
• 1997
  • 1997-04-02 EP EP97913976A patent/EP0891442A4/de not_active Withdrawn
  • 1997-04-02 CA CA002251191A patent/CA2251191A1/en not_active Abandoned
  • 1997-04-02 WO PCT/AU1997/000182 patent/WO1997038164A1/en not_active Application Discontinuation
  • 1997-04-02 NZ NZ331961A patent/NZ331961A/xx unknown

Patent Citations (6)

Non-Patent Citations (1)

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