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
  • D21H19/00—Coated paper; Coating material
  • D21H19/36—Coatings with pigments
  • D21H19/44—Coatings with pigments characterised by the other ingredients, e.g. the binder or dispersing agent
  • D21H19/54—Starch
• • 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
  • D21H17/24—Polysaccharides
  • D21H17/28—Starch
• • 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
  • D21H17/24—Polysaccharides
  • D21H17/28—Starch
  • D21H17/29—Starch cationic

Definitions

• This invention relates to a process for surface sizing or coating paper.
• the surface sizing of paper is a coating treatment which serves to make the surface of paper sufficiently smooth and strong, inter alia to improve the writing quality of the paper.
• the paper surface is provided with a layer of pigment, which serves inter alia to obtain a glossy and well printable surface.
• amylopectin starch types types of starch that do not contain amylose, the so-called amylopectin starch types.
• starch esters or starch ethers which exhibit a lesser tendency to retrograde owing to the introduction of substituents into the amylose molecules.
• additives which increase the viscostability of the starch solutions.
• appropriately modifying starch is laborious, while the addition of additives results In starch solutions having a more complex composition.
• the reagents used for etherifying or esterifying starch, the by-products formed in the process and/or the additives used may be undesirable with respect to toxicity and the environment.
• a first object of the invention is to provide a process as described in the preamble, in which an aqueous size or coating liquid is used which possesses a reduced and stable viscosity, so that that liquid can be used readily and reliably for a long time.
• Another object of the invention is to provide such a process which yields a surface size layer or coating layer with a good film strength and binding force.
• Yet another object of the invention is to provide a process for surface sizing paper, in which an aqueous size liquid is used in such a manner that an increase of the starch retention is effected or that, given the same starch retention, greater ease of handling and processability of the size liquid are achieved.
• Still another object of the invention is to provide a process for coating paper, in which an aqueous coating liquid is used which also contains a high concentration of pigment particles in suspension, that coating liquid possessing an improved rheology.
• an aqueous size or coating liquid which contains converted starch which has been obtained by treating a gelatinized modified starch in aqueous medium with a starch-converting enzyme selected from the group of the cyclodextrin glycosyl transferases (EC 2.4.1.19) or by treating a gelatinized starch or a gelatinized modified starch in aqueous medium with a starch-converting enzyme selected from the group of the branching enzymes (EC 2.4.1.18).
• Cyclodextrin glycosyl transferases (EC 2.4.1.19), CGT enzyme for short, are enzymes which via an exomechanism are capable of splitting off ring-shaped cyclodextrin molecules (having 6, 7 or 8 glucose units) from starch molecules, as for example described in WO89/01043 or WO92/13962.
• Branching enzymes (EC 2.4.1.18) are enzymes capable of converting ⁇ -1,4-glycosidic bonds in starch molecules to an ⁇ -1,6-bond.
• CGT enzyme and branching enzyme belong to the starch-converting enzymes, whereby during the conversion the reducing capacity of the starch product is not increased or is increased only to a very minor extent.
• starch As starting material for obtaining the converted starch to be used in accordance with claim 1 all native (unmodified) starch types can be used, such as potato starch (which may contain 20 to 100 % by weight amylopectin), maize starch, wheat starch, tapioca starch or waxy maize starch. With particular advantage amylose-containing starches are used. Also usable as starting material in accordance with claims 1 and 2 are modified starches, such as starch esters, starch ethers, including cationic starch, and cross-linked starch.
• the employed cyclodextrin glycosyl transferase (EC 2.4.1.19) can originate from different sources, such as described in the following publications: R.L. Whistler, J.N. Bemiller, E.F. Paschall (Eds) Starch: Chemistry and Technology, Second Edition, 1984, Academic Press, pp. 143-144; D. Duchêne (Ed), Minutes of the Fifth International Symposium on Cyclodextrins, Editions de Santé, Paris 1990, pp. 19-61; and A.R. Hedges (Ed), Minutes of the Sixth International Symposium on Cyclodextrins, Editions de Santé, Paris 1992, pp. 23-58.
• European patent specification 0,418,945 describes processes for obtaining branching enzymes (EC 2.4.1.18).
• the starch For an effective action of the CGT-enzyme or the branching enzyme on the starch molecules, the starch must be in gelatinized condition.
• the gelatinization of the starch can be carried out batchwise or continuously in a steam injection device (jet-cookers).
• the enzyme can be added before or after the gelatinization.
• the starch, in the form of a suspension, wet cake or dry product is first mixed in the desired ratio with the enzyme preparation and, if necessary, dried.
• the dried mixed product (compound) can then be mixed with water in the paper factory, whereafter the starch is gelatinized and the conversion is carried out to obtain a converted starch solution for use in surface sizing or coating paper in accordance with the invention.
• the conversion conditions can vary within wide limits and depend in particular on the starting material, the enzyme, the origin of the enzyme and the desired extent of conversion. Suitable conditions are mentioned in the patent specifications mentioned hereinbefore.
• the enzyme used can be inactivated, for instance by increasing the temperature of the conversion mass.
• the converted starch solution obtained can be diluted with water to the desired processing concentration for surface sizing or coating paper. (SW49).
• ⁇ -amylase enzyme preparation Novoban 240.
• CGT-enzyme cyclodextrin glycosyl transferase (EC 2.4.1.19)
• Branching enzyme (EC 2.4.1.18) enzyme preparation obtained according to European patent specification 0,418,945.
• the degree of branching of a starch product was determined by measuring the DE (Dextrose Equivalent) of the starch product after debranching with the enzyme iso-amylase. The higher the DE (after debranching), the higher the degree of branching. Upon debranching, potato starch gives a DE of 5.
• the additionally branched starch was prepared by treating an aqueous solution of potato starch with a branching enzyme preparation. This treatment took place at 50°C for 16 hours. The reaction was discontinued by heating to 100°C. Then the starch solution was purified by means of filtration. The filtrate was then sprayed-dried to a dry additionally branched starch product.
• the viscosity of the starch solutions was determined with a Brookfield viscosimeter, type LVT.
• the ⁇ -amylase converted starch solutions were produced as follows. To a suspension of starch in water (30% by weight starch) was added 0.025% by weight (based on dry substance) of an ⁇ -amylase preparation. This suspension was heated with direct steam (3°C per minute) to 75°C. Then the converted starch solution obtained was passed through a jet-cooker, where the enzyme was inactivated at 140°C for 45 seconds.
• the coating composition contained 100 parts by weight of SPS-clay, 12.5 parts by weight of starch product and water. Table 2 shows the properties of the coating composition. Properties coating composition Properties Additionally branched potato starch Oxidized potato starch Dry substance % 70.3 69.1 Water retention gr 0.5/1.5 kg/cm 2 5/5 5/20 Brookfield 100 rpm, mPa.s 1160 1520 Hi-shear, 1100 rpm, mPa.s 332 247 Brookfield after 24 h. mPa.s 1040 1880
• the coating composition was applied to a fine-grade coating base paper (80g/m 2 ; manufacturer Nymölla), using a puddle type blade (Jagenberg; speed 50 m/min.) of the Dixon (approximately 10 g/m 2 ).
• the coated paper was dried to 5% by weight of moisture.
• the paper samples were conditioned and tested at 23°C and 50% relative humidity.
• the properties of the coated papers are shown in Table 3. Properties of coated papers Properties Additionally branched potato starch Oxidized potato starch Whiteness % 108.1 107.6 Smoothness sec/10 ml 27.4 26.6 Porosity 3.1 2.6 IGT-pick VVP 960 1010 fürbau pick >3 >3

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• Paper (AREA)
• Adhesives Or Adhesive Processes (AREA)
• Paints Or Removers (AREA)

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• 1994
  • 1994-06-29 NL NL9401090A patent/NL9401090A/nl not_active Application Discontinuation
• 1995
  • 1995-06-27 ES ES95201751T patent/ES2151575T5/es not_active Expired - Lifetime
  • 1995-06-27 EP EP95201751A patent/EP0690170B2/en not_active Expired - Lifetime
  • 1995-06-27 AT AT95201751T patent/ATE196172T1/de not_active IP Right Cessation
  • 1995-06-27 DK DK95201751T patent/DK0690170T4/da active
  • 1995-06-27 DE DE69518702T patent/DE69518702T3/de not_active Expired - Fee Related

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