EP0514595A1 - Verfahren zur Herstellung des satinierten Papiers und Kartonbahnen unter Verwendung des Impulstrockners - Google Patents

Verfahren zur Herstellung des satinierten Papiers und Kartonbahnen unter Verwendung des Impulstrockners Download PDF

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Publication number
EP0514595A1
EP0514595A1 EP19910304518 EP91304518A EP0514595A1 EP 0514595 A1 EP0514595 A1 EP 0514595A1 EP 19910304518 EP19910304518 EP 19910304518 EP 91304518 A EP91304518 A EP 91304518A EP 0514595 A1 EP0514595 A1 EP 0514595A1
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EP
European Patent Office
Prior art keywords
paper
impulse
coating
sheet
coated
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Withdrawn
Application number
EP19910304518
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English (en)
French (fr)
Inventor
Raquiba H. Arnold
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Union Camp Corp
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Union Camp Corp
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Publication date
Application filed by Union Camp Corp filed Critical Union Camp Corp
Priority to EP19910304518 priority Critical patent/EP0514595A1/de
Publication of EP0514595A1 publication Critical patent/EP0514595A1/de
Withdrawn legal-status Critical Current

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    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21G—CALENDERS; ACCESSORIES FOR PAPER-MAKING MACHINES
    • D21G9/00—Other accessories for paper-making machines
    • D21G9/009—Apparatus for glaze-coating paper webs
    • 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
    • D21H25/00—After-treatment of paper not provided for in groups D21H17/00 - D21H23/00
    • D21H25/08—Rearranging applied substances, e.g. metering, smoothing; Removing excess material
    • D21H25/12—Rearranging applied substances, e.g. metering, smoothing; Removing excess material with an essentially cylindrical body, e.g. roll or rod
    • D21H25/14—Rearranging applied substances, e.g. metering, smoothing; Removing excess material with an essentially cylindrical body, e.g. roll or rod the body being a casting drum, a heated roll or a calender

Definitions

  • This invention relates to the manufacture of coated paper products, and in particular, to manufacturing coated papers having improved properties and reduced manufacturing costs.
  • the production of high quality printing paper typically includes various finishing operations which include coating the paper with pigments and binder followed by smoothing the paper by passing it through either a series of nips or one nip formed by rolls that may or may not be heated.
  • the coating is generally applied by coaters of conventional designs, such as blade coaters or roll coaters.
  • One or more coating applications can be applied to one or both sides of the paper.
  • a coated paper is then introduced into equipment which imparts smoothness and gloss to the surface. Such equipment includes supercalenders, machine calenders and gloss calenders.
  • Coated paper is commonly supercalendered by passing it through a series of nips under high load at elevated temperatures.
  • the paper usually enters the supercalender stacks at a relatively high moisture content of about 7-9%.
  • the nips of the supercalendering equipment provide a shearing action which results in a smooth paper with a high gloss.
  • the high pressure associated with supercalendering compresses and densifies the paper, which typically limits the process to production of low caliper paper. For this reason, paper board for high quality printing is not usually supercalendered.
  • Supercalendering also has the effect of reducing opacity, which is undesirable.
  • the complexity of the supercalendering process also adds significantly to the processing time and the manufacturing cost of the paper.
  • Attwood teaches a process that requires rewetting the paper or paper board prior to pressing the moist surface against a smooth polished cylinder, similar to gloss calendering.
  • Vreeland discloses as a finishing step the process of high temperature gloss calendering at low moisture contents to attain high gloss and smoothness. Neither of these disclosures significantly simplifies the paper-making operation so as to produce higher quality papers with less complexity, and, at best, corrects inherent problems concerning lack of smoothness of the base paper as formed.
  • Impulse drying Another technique for regulating the surface properties and consistency of paper, referred to by those in paper-making arts as "impulse drying", has received considerable attention of late.
  • Impulse drying employs high temperatures, high pressures and moderately long residence times to remove water much more efficiently than conventional pressing, with large energy savings.
  • Impulse drying both dries and densifies the fibers of the sheet by compressing a web of fibers between heated nip rollers.
  • impulse dried paper is suitable for writing and printing papers such as newsprint. Lavery, "Impulse Drying of Newsprint," Journal of Pulp and Paper Science , Vol. 13, No. 6, pp. J178-J184, November, 1987, also hereby incorporated by reference. Nevertheless, the effect on coated printing papers has not been investigated and prior speculation about the use of impulse dried paper for coating applications has revealed doubts about whether the coating could adhere to the impulse dried surface because of its low permeability.
  • This invention provides a method of making coated paper or paper board by providing a web of paper-making fibers, preferably having a consistency of at least about 20% solids, and impulse drying this web at a temperature of at least the glass transition temperature of the paper-making fibers at the level of moisture in the fibers, to produce an impulse dried sheet preferably having a consistency of at least about 50% solids and a Parker Print Smoothness of less than about 6.5 microns upon completion of drying.
  • This novel method further includes surface coating the impulse dried sheet to obtain a coated sheet having improved properties. The surface properties of the impulse dried paper reduce the finishing requirements necessary for producing an improved coated sheet.
  • a new process for the manufacture of coated paper and paper board which permits the high gloss and smoothness of supercalendered coated papers without the loss in bulk or opacity associated with supercalendering.
  • This invention makes use of the properties imparted to a base sheet during impulse drying and uses these properties to make high quality coated paper in an unexpected and improved manner.
  • the invention includes calendering, such as gloss calendering, the coated sheet to provide a product with high gloss and better smoothness at a lower average density than a supercalendered sheet.
  • the process enables a relatively thin coating of about 3-5 lbs/3000 ft2 and moderate gloss calendering conditions to produce a coated paper product similar to a No. 3 coated offset paper, but with higher bulk and better smoothness.
  • the process also results in substantial savings in manufacturing costs through the reduction of energy usage, materials and time required to produce the product.
  • a coated paper or paper board is manufactured by first providing a web of paper-making fibers having a consistency of at least about 20% solids. This web is then impulse dried at a temperature of at least about the glass transition temperature of the paper-making fibers to produce an impulse dried sheet having a consistency of at least about 50% solids and a Parker Print Smoothness of less than about 6.5 microns upon completion of drying. Following impulse drying, the impulse dried sheet is surface coated to obtain a coated sheet.
  • glass transition temperature of the paper-making fibers refers to the temperature at which the cellulose fibers begin to form an amorphous, glass-like substance and bond to one another.
  • the "glass transition temperature" would constitute a weighted average of the individual glass transition temperatures for each type of furnish.
  • the glass transition temperature of the furnish is lowered as the moisture content is increased, so the glass transition temperature at the furnish consistency is the preferred temperature of the fibers during impulse drying.
  • a web of paper-making fibers having a consistency of about 20-30% solids.
  • This web is then impulse dried at a temperature of at least about the glass transition temperature of the paper-making fibers to produce an impulse dried sheet having a consistency of about 65-99% solids and a Parker Print Smoothness of about 3.0-5.5 microns.
  • the impulse dried sheet is then surface coated with a coating of about 3-5 lbs. per 3000 sq ft. to obtain a wet coated sheet.
  • the wet coated sheet is then dried to produce a substantially dry coated sheet, and the dry coated sheet is then gloss calendered at a temperature of about 250-350°F and a nip pressure of about 300-700 pli.
  • This invention also provides coated paper and paper board comprising an impulse dried surface having a coating of about 3-12 lbs. per 3000 sq. ft.
  • the coating comprises a gloss calendered finish having a gloss of about 64-68%, a Parker Print Smoothness of less than about 1.5 microns, a bulk of greater than about .9 cm3/g, and a caliper of above about 3 mils.
  • This invention also provides fine coated paper comprising an impulse dried surface having a coating of about 3-5 lbs/3000 ft2.
  • This coating comprises a gloss calendered finish having a gloss of about 64-68%, a Parker Print Smoothness of less than about 1.0 microns, and bulk of about 1.07-1.19 cm3/g, a caliper of about 3.2-3.8 mils, and a basis weight of above about 30 lbs/3000 sq. ft.
  • the paper-making fibers of this invention are formed into a paper web of at least about 20% solids, and more preferably 20-30% solids.
  • the moisture level is typical of paper webs formed on a fourdrinier paper machine just before conventional pressing.
  • the sheets are then carried to the impulse drying apparatus using drier felts for absorbing some of the water from the web during the impulse drying step.
  • the apparatus for the impulse drying step of this invention can include a heated drier drum capable of reaching temperatures up to about 700°F.
  • the impulse drying step dries the web at a temperature of about 300-900°F, and more preferably about 400-600°F.
  • the heated drier drum is preferably in contact with another drum for forming a nip capable of reaching nip pressures of about 0.3-7 MPa.
  • Exposure times generally can run from about 15-100 milliseconds, although about 20-60 milliseconds is preferred. Reference is made to U.S. 4,324,613, which describes impulse drying techniques more fully.
  • the sheets were impulse dried using one nip at 600°F and two different pressures, 287 and 445 psi, and two different dwell times, 98 and 50 milliseconds. Specific conditions for each of the samples are listed in Table I below.
  • the solids content increased to over 69% for each of the samples.
  • pressing conditions of conventional processes increase the solids content only slightly from about 25% to about 31%.
  • the fibers in the web consolidate more completely than in conventional processing, and the structure is effectively locked in.
  • the increased solids level after impulse drying further reduces deformation of the fibers from additional process steps.
  • the fibers of the web shrink and deform much more in conventional pressing and drying than in impulse drying, since they are relatively unrestrained.
  • impulse drying the web is preferably held against a heated steel roll at high temperature and pressure and for a relatively short time, making the fibers highly constrained as they dry. This permits the fibers to consolidate and the structure is locked in.
  • the impulse dried sheet is less dense than a conventional pressed, coated and calendered paper.
  • the surface coating step of the preferred method can include conventional apparatuses such as air knife coating or blade coating.
  • about 1-12 lbs/3000 ft2, and more preferably 3-5 lbs/3000 ft2 of coating material is employed for coating a single side of the paper or paper board of this invention. Both sides may also be coated.
  • the coatings can contain standard pigments and binders typically used in coating paper.
  • a typical composition is about 80 wt.% No. 1 kaolin clay and about 20 wt.% fine ground calcium carbonate as a pigment with styrene butadiene as a binder.
  • This coating was not optimized for properties but will provide a glossy, smooth product.
  • the coating solids should be relatively high to minimize the amount of water applied to the sheet.
  • the coating may be applied at e.g. 5 lbs/3000 sq. ft. to the impulse dried side of the sheets. This amount of coating is less than the usual amount applied in standard coating practices for high quality papers.
  • blade coaters are typically employed by manufacturers of coated paper. Blade coaters can compensate for the roughness of a base sheet and can cover irregularities if enough coating is applied.
  • An air knife coater follows the contours of the substrate surface. Air knife coaters are commonly used as a top coat after a smooth surface has already been laid down by a blade coater for coated board grades. Since the surface of such impulse dried sheets is already smooth, a smooth coated surface can be obtained even using an air knife coater with a single coating application. Even better quality is obtained if a blade coater is used on an impulse dried base sheet.
  • the coated sheet will be wet and thereafter dried.
  • the coating drying operation preferably employs hot air blown onto the coated surface.
  • infrared driers can be used to quickly set the coating. Infrared is usually used under special circumstances, and generally results in better qualities since it reduces the penetration of coating into the sheet by shortening the time the coating is wet.
  • the low surface porosity of an impulse dried sheet already minimizes coating penetration, and thus the need for infrared drying can be reduced or eliminated.
  • drying the coating on an impulse dried sheet is easier since the coating is held out on the surface, rather than absorbed. Less energy and/or less time is used to dry the coatings since rewetting of the underlying base sheet is minimized.
  • the efficiency of coating driers decreases dramatically if the underlying base sheet is too wet.
  • the base sheet can become too wet if a high amount of coating is required needed to cover a rough base sheet to obtain high quality. These inefficiencies can be reduced or eliminated if the base sheet is impulse dried.
  • the most preferred method of this invention further includes gloss calendering the substantially dry coated sheet to produce a fine paper.
  • Gloss calendering is a common finishing operation which produces high gloss surface finishes without the densification associated with supercalendering.
  • the technique uses heated rolls preferably having a temperature of at least about 225°F and more preferably about 250-350°F with moderated nip pressures of about 250-1000 pli, more preferably 300-700 pli, and primarily affects only the uppermost surface of the paper, which is usually coated. Because there is less densification, better opacity results, but the sheet is generally not as smooth as supercalendered products.
  • Gloss calendering equipment can be used in-line with the main paper production equipment, while supercalendering generally is not.
  • Coated impulse dried sheets that were tested pursuant to this invention were gloss calendered using a soft rubber covered backing roll at about 300°F and about 300 pli. The calendering conditions were thus relatively mild for producing glossy coated paper. These conditions were typical of coated board produced on-machine. As a result, while the caliper of the coated impulse dried sheets was not reduced very much at all, a very glossy smooth surface similar to a supercalendered sheet was unexpectedly obtained.
  • the preferred calendering step of this invention can be accomplished with machine calendering.
  • the coated paper passes through a nip between two hard rolls at high pressure and moderate temperature.
  • the machine calender densifies the web and is used to control the caliper of the sheet.
  • Machine calendering also produces smoothness but generally with little gloss.
  • the equipment is fairly standard for finishing operations for paper and paper board and is usually used in-line with the main paper production equipment.
  • a 12" wide web was formed on a web former using 40 dry pounds of bleached chemical pulp containing high amounts of southern hardwood, 25-30% solids. Specifically, the furnish contained 85% hardwood and 15% pine; 80 pulp brightness; and 370 S/R freeness. The pulp was reslushed in a laboratory beater and delivered directly to the head box.
  • the web former used was basically a head box, a Fourdrinier wire with vacuum-assisted drainage, a small one nip press roll and a spindle for winding up the wet web
  • the targeted basis weight was about 75 lbs/3000 ft2.
  • the wet web was impulse dried using consistencies, dwell times and temperatures which were chosen by considering the limitations of impulse dryers and the technical feasibility of these parameters in practical applications.
  • the samples employed impulse drying parameters which included nip temperatures of 400, 500, and 600°F; nip dwell times of 20 and 50 milliseconds; and an average nip pressure of 400 pli. These experiments used one nip on one side of the web surface. Additionally, experiments were run which included, in the first instance, the use of 400°F for two nips on both sides of the web surface, and, in the second instance, a first nip of 600°F and a second nip of 400°F. A control was run at 100°F, 20 milliseconds, and 400 pli average nip pressure.
  • nip pressure was held constant throughout the trial at an average pressure of about 400 pli. This pressure is not unlike conventional pressing. Experiments showed that higher nip pressures do not significantly improve smoothness and may interfere with runability.
  • impulse drying After impulse drying, it was noted that the impulse dried web was significantly drier, but because the dwell times were shorter and the basis weight was higher, the same degree of drying found with handsheets was not observed in this experiment. Drying the webs was completed on a laboratory drum dryer.
  • the ingoing consistency for impulse drying generally was between about 32-34% and the outgoing consistency varied with the conditions listed in Table IV below.
  • the wire side of the web was toward the heated roll and the felt was on the top side.
  • a liner board felt was used in these experiments so the felt side of the sheet was much rougher than ideal, which was subsequently reflected in the smoothness parameters for this side.
  • the wire side was toward the first heated nip and the top side was toward the second heated nip.
  • felt marking was observed on both sides of the sheet because the sheet was in contact with a felt at some point. Felt marking was more severe on the wire side of the sheet since it was the last side to have a felt on it.
  • the uncoated impulse dried webs were subjected to both physical and print lab testing. Scattering coefficients were determined and used as a measure of how well bonded the fibers in the sheet became with impulse drying.
  • the scattering coefficient for the impulse dried sheets increased about linearly with bulk. It was determined, therefore, that better bonding is usually found for denser sheets and the scattering coefficient decreases with increases in bonded area.
  • the average bulk of the impulse dried sheet was found to be lower than for conventional pressed and dried sheets. Impulse drying, therefore, increases the flexibility for obtaining different properties which depend on bulk.
  • Sheet porosity was found to change significantly with impulse drying compared to standard pressing and drying as described in FIG. 1. Gurley porosity was shown to increase as the sheet is densified. The increase was different but not as high with two nip impulse drying. With two heated nips in subsequent operations, water is probably forced through the first impulse dried side causing it to be more open. The impulse dried sheets were found to be much less open than the control and standard pressed sheets made from this type of furnish. The data for the standard conditions was obtained from pressed and calendered handsheets.
  • the impulse dried base sheets of this invention are not limited to fine paper production and can be used as a starting material for a multitude of paper products.
  • the base sheet can be treated with a pigmented size press application to produce machine finished pigment grades or treated with a light blade coating to produce light weight coated paper.
  • the base sheet could alternatively be coated using any formulation or coating equipment to achieve the quality of any supercalendered coating grade of paper, such as No. 2, or No. 1, etc.
  • the base sheet can be treated by more than one coating application to produce, for example, double coated and triple coated grades.
  • the base sheet can alternatively be coated and finished by other art recognized processes for achieving smoothness and/or gloss.
  • this invention can be used to manufacture products which typically use coating to impart a specialized surface finish in which keeping the coating on the surface and keeping that surface as smooth as possible is a desired effect.

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EP19910304518 1991-05-20 1991-05-20 Verfahren zur Herstellung des satinierten Papiers und Kartonbahnen unter Verwendung des Impulstrockners Withdrawn EP0514595A1 (de)

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Application Number Priority Date Filing Date Title
EP19910304518 EP0514595A1 (de) 1991-05-20 1991-05-20 Verfahren zur Herstellung des satinierten Papiers und Kartonbahnen unter Verwendung des Impulstrockners

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Application Number Priority Date Filing Date Title
EP19910304518 EP0514595A1 (de) 1991-05-20 1991-05-20 Verfahren zur Herstellung des satinierten Papiers und Kartonbahnen unter Verwendung des Impulstrockners

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0969141A1 (de) * 1998-06-29 2000-01-05 Voith Sulzer Papiertechnik Patent GmbH Verfahren zur Erzeugung von satiniertem Papier
EP1052328A2 (de) * 1999-05-14 2000-11-15 Voith Sulzer Papiertechnik Patent GmbH Tiefdruck-Papier und Herstellungsverfahren für dieses Papier
US6447643B2 (en) * 1998-10-01 2002-09-10 Sca Hygiene Products Ab Method of producing a wetlaid thermobonded web-shaped fibrous material and material produced by the method
US8349443B2 (en) 2006-02-23 2013-01-08 Meadwestvaco Corporation Method for treating a substrate

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4596633A (en) * 1983-10-24 1986-06-24 The Black Clawson Company Surface treatment of paper and paperboard
US4624744A (en) * 1984-05-18 1986-11-25 S. D. Warren Company Method of finishing paper utilizing substrata thermal molding
DE3535685A1 (de) * 1985-10-05 1987-04-09 Billhofer Maschf Gmbh Verfahren und vorrichtung zum kalandrieren von mit lack beschichteten bogen

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4596633A (en) * 1983-10-24 1986-06-24 The Black Clawson Company Surface treatment of paper and paperboard
US4624744A (en) * 1984-05-18 1986-11-25 S. D. Warren Company Method of finishing paper utilizing substrata thermal molding
DE3535685A1 (de) * 1985-10-05 1987-04-09 Billhofer Maschf Gmbh Verfahren und vorrichtung zum kalandrieren von mit lack beschichteten bogen

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0969141A1 (de) * 1998-06-29 2000-01-05 Voith Sulzer Papiertechnik Patent GmbH Verfahren zur Erzeugung von satiniertem Papier
US6264794B1 (en) 1998-06-29 2001-07-24 Voith Sulzer Papiertechnik Patent Gmbh Process for manufacturing glazed paper
US6447643B2 (en) * 1998-10-01 2002-09-10 Sca Hygiene Products Ab Method of producing a wetlaid thermobonded web-shaped fibrous material and material produced by the method
EP1052328A2 (de) * 1999-05-14 2000-11-15 Voith Sulzer Papiertechnik Patent GmbH Tiefdruck-Papier und Herstellungsverfahren für dieses Papier
EP1052328B1 (de) * 1999-05-14 2006-09-27 Voith Patent GmbH Herstellungsverfahren für ein Tiefdruck-Papier
US8349443B2 (en) 2006-02-23 2013-01-08 Meadwestvaco Corporation Method for treating a substrate
US8673398B2 (en) 2006-02-23 2014-03-18 Meadwestvaco Corporation Method for treating a substrate

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