WO2017017316A1 - Procédé pour éliminer l'humidité de voiles fibreux - Google Patents

Procédé pour éliminer l'humidité de voiles fibreux Download PDF

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Publication number
WO2017017316A1
WO2017017316A1 PCT/FI2016/050546 FI2016050546W WO2017017316A1 WO 2017017316 A1 WO2017017316 A1 WO 2017017316A1 FI 2016050546 W FI2016050546 W FI 2016050546W WO 2017017316 A1 WO2017017316 A1 WO 2017017316A1
Authority
WO
WIPO (PCT)
Prior art keywords
fibre web
paper
drying
web
printing
Prior art date
Application number
PCT/FI2016/050546
Other languages
English (en)
Inventor
Jukka SAHIVIRTA
Original Assignee
Oy Keskuslaboratorio - Centrallaboratorium Ab
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Oy Keskuslaboratorio - Centrallaboratorium Ab filed Critical Oy Keskuslaboratorio - Centrallaboratorium Ab
Publication of WO2017017316A1 publication Critical patent/WO2017017316A1/fr

Links

Classifications

    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21G—CALENDERS; ACCESSORIES FOR PAPER-MAKING MACHINES
    • D21G7/00—Damping devices
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B5/00—Drying solid materials or objects by processes not involving the application of heat
    • F26B5/04—Drying solid materials or objects by processes not involving the application of heat by evaporation or sublimation of moisture under reduced pressure, e.g. in a vacuum
    • F26B5/047—Drying solid materials or objects by processes not involving the application of heat by evaporation or sublimation of moisture under reduced pressure, e.g. in a vacuum for continuous drying of material in long length, e.g. webs
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41F—PRINTING MACHINES OR PRESSES
    • B41F23/00—Devices for treating the surfaces of sheets, webs, or other articles in connection with printing
    • B41F23/007—Devices for treating the surfaces of sheets, webs, or other articles in connection with printing with heat treatment before printing
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41F—PRINTING MACHINES OR PRESSES
    • B41F23/00—Devices for treating the surfaces of sheets, webs, or other articles in connection with printing
    • B41F23/04—Devices for treating the surfaces of sheets, webs, or other articles in connection with printing by heat drying, by cooling, by applying powders
    • B41F23/0403—Drying webs
    • B41F23/0423—Drying webs by convection
    • B41F23/0426—Drying webs by convection using heated air
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41F—PRINTING MACHINES OR PRESSES
    • B41F23/00—Devices for treating the surfaces of sheets, webs, or other articles in connection with printing
    • B41F23/04—Devices for treating the surfaces of sheets, webs, or other articles in connection with printing by heat drying, by cooling, by applying powders
    • B41F23/0486—Particular types of dryers
    • B41F23/0489—Vacuum dryers
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
    • D21F5/00—Dryer section of machines for making continuous webs of paper
    • D21F5/14—Drying webs by applying vacuum
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21G—CALENDERS; ACCESSORIES FOR PAPER-MAKING MACHINES
    • D21G1/00—Calenders; Smoothing apparatus
    • D21G1/0073—Accessories for calenders
    • D21G1/0093—Web conditioning devices

Definitions

  • the present invention relates to the processing of fibre webs.
  • the invention relates to a method, according to the preamble of Claim 1, for removing moisture in a fibre web.
  • the invention also relates to a drying device for a moist, moving, fibre web, according to the preamble of Claim 18.
  • a drying device for a moist, moving, fibre web, according to the preamble of Claim 18.
  • Such a device generally comprises a heating unit, which is arranged to heat the fibre web, in order to remove water by vaporization at a temperature of at least 50 °C.
  • the invention also relates to use according to Claim 27.
  • the fluting of paper as a phenomenon is a typical and characteristic problem in so-called heatset-offset printing.
  • This printing method is the most-used in the world, if production is calculated in terms of paper consumption. Fluting appears in printed products as variations in shape, with a frequency of a few millimetres, in the direction of running. This phenomenon has been studied for a long time in several places, with no solution to it having yet been found, even though the reasons for it are known.
  • the printing method is, in terms of its price-quality relationship, the best for large and medium printing runs (50 000 - 500 000 items), the problem has had to be tolerated and it has also been accepted. The least satisfied have been advertisers and the publishers of high-quality journals and catalogues.
  • Fluting is due to the paper's moisture and the hot-air drying used in the printing method.
  • Part of the surface of the paper web is covered in printing ink and part is not printed, depending on how images, texts, and other colour surfaces are designed and positioned in the product.
  • Water evaporates more slowly from areas covered by printing ink than from unprinted surfaces, so that the paper's fibres shrink to a different extent in the cross direction of the paper web and the paper acquires a corrugated shape.
  • the tensile stress in the paper can be adjusted during printing, but this cannot be done in the cross direction, even though it could prevent the web from shrinking.
  • the cause of the problem is water, the amount of it in paper should be reduced.
  • Fluting has been less in so-called waterless offset, in which the printing plates and inks are more expensive.
  • the paper web By drying the paper web with hot air just before the printing unit the paper dries and fluting is reduced significantly.
  • the hot paper raises the temperature in the following print units and the printing ink, thus reducing the viscosity of the ink and causing the half-tone dots being printed to enlarge as the ink spreads more. This reduces the contrast of the impression and thus reduces its quality.
  • the present invention is intended to remove at least some of the drawbacks of the prior art and create a new type of solution for removing moisture from fibre webs, such as paper and board webs.
  • the task is to create a method for removing moisture from a paper or board web to be fed to a printing machine, in such a way that fluting is reduced at the same time as the quality of the printing result is maintained or even improved.
  • the invention is based on the idea of removing the moisture of a fibre web, such as an unprinted fibre web, in a partial vacuum.
  • the removal of the solvent contained in a printing ink by vacuum is previously known.
  • Publication DE 3 411 752 discloses a vacuum chamber arranged after a printing machine, the purpose of which is to remove the solvent contained in printing ink by a gas or a vacuum.
  • GB patent publication 935 063 also discloses a solution, based on the use of a vacuum, for drying printing inks.
  • FR patent publication 1 397 222 discloses the drying of webs consisting of various materials, for instance, fabrics, leather, and paper, in a vacuum, the aim of which is to shorten the drying time, when the webs can also be stretched, if desired.
  • US patent publication 4 053 990 discloses the removal of solvents and solvent mixtures, such as mixtures of water and organic solvents, from web-shaped materials by means of a vacuum.
  • vacuum drying can be combined with heating of the fibre web and that it is best implemented in such a way that, after vacuum drying, the temperature of the fibre web is reduced to less than room temperature.
  • the fibre web is brought to a temperature of more than 50 °C, after which it is subject to vacuum evaporation, in connection with which the temperature of the web is reduced to less than 20 °C.
  • the apparatus according to the invention comprises a vacuum evaporator, which is arranged after the heating unit in the direction of movement of the fibre web, and which is arranged to remove water by evaporating it at a temperature of less than 20 °C.
  • the method described can be used to pre-dry a printing base, such as paper, in order to reduce the fluting of paper printed in heatset-offset printing.
  • the method according to the invention is mainly characterized by what is stated in the characterizing portion of Claim 1.
  • the apparatus according to the invention is, for its part, characterized by what is stated in the characterizing portion of Claim 18.
  • the use according to the invention is characterized by what is stated in Claim 27.
  • pre-heating preceding the vacuum drying is combined with the hot-air circulation of a dryer and/or reheating, which are arranged after the printing press, when the web being fed to the vacuum unit can be heated using recirculated residual heat and finally dried using vacuum.
  • the web can be cooled when the final moisture evaporates, so that the printing ink attaches and adheres to it well, dot
  • Vacuum evaporation together with pre-heating is an easy and cheap solution, because the paper does not yet have printing ink in it, which could smudge on the rolls in the closed vacuum chamber. Preferred embodiments and the advantages gained by them are described below.
  • Figure 1 shows a schematic diagram of four-colour printing, in which, before a heatset- offset printing press, a vacuum dryer according to one embodiment of the invention is arranged, by which moisture is removed immediately before printing;
  • Figure 2 shows a side view of the schematic construction of a vacuum chamber according to one embodiment of the invention.
  • the fibre web is first brought to a temperature of over 50 °C, after which it is subjected to vacuum evaporation, in connection with which the web's temperature is reduced to under 20 °C.
  • the web's temperature is reduced to under 20 °C.
  • Operation preferably takes place in such a way that vacuum evaporation is performed immediately after the heating stage, so that the temperature of the fibre web does not drop substantially before vacuum evaporation.
  • this can be implemented by arranging the vacuum chamber immediately after the heating unit.
  • the solution described is generally suitable for drying paper and board, when vacuum evaporation is combined with the drying section of the paper or board machine.
  • the solution presented here can be arranged after the drying cylinders as the final drying stage before the finishing of the fibre web.
  • one or more conventional drying cylinders can be replaced using the present solution. It has been shown that it is possible to replace a significant part, of up to half of the drying cylinders of a conventional drying section. In practice, 1/20 - 1/3 of the drying cylinders are replaced. The solution can thus be used to reduce the energy consumption of drying. Especially advantageously, the vacuum drying described in this case is arranged at the end of the drying section.
  • the moisture content of the paper or board web brought to the vacuum drying is at most 50 %, for example, at most 40 %, most suitably at most 30 % or at most 25 % or at most 20 %.
  • vacuum drying can be used to reduce the moisture of the paper or board web to its desired final value, e.g. to about 2 - 8 %, especially to about 4 - 6 %.
  • vacuum evaporation is performed in connection with the printing press.
  • the fibre web then comprises a printing base, such as the paper or board web to be printed, and this is brought to vacuum evaporation immediately before it is fed to the print unit of the printing press.
  • the printing press is an offset printing press and the vacuum
  • evaporation is performed immediately before the first print unit of the printing press, seen in the direction of movement of the printing base.
  • the offset printing press is a heatset-offset printing press, such as a four-colour heatset-offset printing press.
  • the fibre web is brought to a low enough temperature to be able to the viscosity of the printing ink brought to the fibre web.
  • the temperature of this is reduced to the range -10.. +2 °C before it is taken to the printing unit.
  • Figure 1 shows a heatset printing press 7 equipped with a vacuum-drying unit 3 - 6.
  • the apparatus comprises, in order (i.e. in the direction of movement of the paper or board web), an unwinder 1, which rolls the paper open, a feed device, by which the paper web is fed and guided to the printing press, a moisture-removal unit 3, in which the paper is heated 4, and which as a unit is connected without a gap to a vacuum chamber 6, in which the desired vacuum is formed by vacuum suction 5.
  • vacuum evaporation is performed in the vacuum chamber, which is essentially airtight.
  • the vacuum chamber is closed to be at least substantially airtight by press rolls, between which the paper web travels into the unit and, dried and cooled, out of it.
  • One embodiment of the construction of the vacuum chamber is shown in greater detail in Figure 2.
  • the vacuum chamber 6 is arranged in connection with the printing press, immediately before the print units 7. Having travelled through the vacuum chamber 6, the paper web transfers immediately to the first print unit 7 of the printing press, in the case of the figure, the black-ink print unit. In the direction of movement of the web, the print units are: Black, Cyan, Magenta, and Yellow.
  • the fibre web's temperature is not able to rise, or rises at most by about 0.1 - 10 °C, for example, at most by about 0.5 - 5 °C before the first print unit.
  • the temperature of the fibre web is kept under the freezing point of water over the whole distance of the printing press's print units (i.e. in the area indicated by the reference number 7).
  • the fibre web travels printed through the four print units 7 to the hot-air dryer 8, where the solvent component of the printing ink is removed by heating the impression.
  • the drying temperature is highest in the first and lowest in the last.
  • the temperature in the present example is about 240 - 270 °C, in the second 180 - 210 °C, and in the third 150 - 170 °C.
  • cooling cylinders 9 are arranged, and after them the web's creasing device, or, when printing packaging, a re-reeler.
  • the temperature after the drying unit can be determined, for example, using an IR thermometer. In the case of the example shown in the figure, the temperature is typically about 130 °C.
  • Figure 1 shows the circulation of hot air from the hot-air dryer 8 to the moisture-removal unit 3, by a line with an arrow, which is drawn to run under the apparatus, from right to left.
  • the drying device for a moist, moving, fibre web comprises, in a combination:
  • a heating unit which is arranged to heat the fibre web to remove water by
  • a vacuum evaporator which is arranged after the heating unit, in the direction of travel of the fibre web, and which is arranged to remove water by evaporating it to a temperature of less than 20 °C.
  • the device described is arranged as part of the drying section of a paper or board machine, at least one drying cylinder preceding the device operates most suitably as the heating unit of the device.
  • FIG. 2 shows the schematic construction of a vacuum dryer according to one
  • the drying section 20 can be closed to become airtight by means of press rolls 25a - 25d, between which the paper web 23 travels into the unit and, dried and cooled, or even frozen, out of it.
  • the fibre web moving in the airtight vacuum chamber is subject to an absolute pressure of about 0.001 - 0.1 bar.
  • a great deal of vacuum can be easily sucked through the suction pipes 21 and 22 using moderate pumping power, due to the closed system.
  • the rolls 25a - 25d against the paper web are rubber surfaced, so that the compression becomes tight.
  • idle rolls 24a - 24d which in this case are chrome-plated.
  • ceramic or steel blades 26a - 26d against the surface of the idle rolls. The task of these blades is to press tightly against the idle rolls 24a - 24d with the aid of a vacuum.
  • the bearings of the rolls are sealed at the end of the roll and against the vacuum chamber (sealing bearings).
  • the preheating section of the device (marked in Figure 1 with the reference number 2) is also closed by rolls, though the tightness demand is not important. The reason is that heat transfer is more efficient in a closed space and waste heat can be returned to preheating the air of the printing press' s actual printing-ink hot-air dryer.
  • the cooling of the paper web keeps the moisture in a solid form, i.e. ice, for about half a second of the time of four-colour printing 7, before final drying 8.
  • the cooling increases the printing ink's viscosity on the paper during the press stage and reduces dot enlargement, which permits better colour reproduction and contrast. It has been shown that it is not worth raising the viscosity of the ink earlier, for example, when preparing the inks, which is due to the ink dosing and the set of ink rolls, and above all the surface strength of the paper.
  • the present technology can be exploited in both printing, such as offset printing and flexo printing, and in paper and board manufacture.
  • the offset printing presses for which the solution is particularly preferably suitable, can be not only heatset-offset but also "coldset", i.e. "non-heatset” -offset printing presses.
  • the present solution is also suitable for water-free offset printing.
  • the fluting phenomenon in printed products which relates mainly to heatset-offset printing and is a nuisance to, for instance, publishers and advertisers, is eliminated.
  • one embodiment encompasses a method for removing moisture from a fibre web, in which method the fibre web is brought to a temperature of over 50 °C, after which it is subjected to vacuum evaporation, in connection with which the temperature of the web is reduced to less than 20 °C, when the said vacuum evaporation is performed in the drying section of the paper or board machine.
  • vacuum evaporation is arranged as part of the drying section of the paper or board machine, possibly at its end, so that it sets the web's final moisture content.
  • the vacuum evaporation is arranged as part of the drying section of the paper or board machine, when it replaces some of the drying cylinders of the drying section of such a paper or board machine.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Molecular Biology (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Drying Of Solid Materials (AREA)
  • Supply, Installation And Extraction Of Printed Sheets Or Plates (AREA)

Abstract

L'invention concerne un procédé et un appareil pour éliminer l'humidité d'un voile de carde. Selon l'invention, le voile de carde est chauffé à une température supérieure à 50 °C, après quoi il est amené à une évaporation sous vide, ce qui implique la réduction de la température du voile à moins de 20 °C. Au moyen du séchage sous vide, une économie d'énergie importante est obtenue pendant la fabrication de papier et de carton. En plus, au moyen du pré-séchage de la base d'impression, c'est-à-dire le papier ou carton, le cannelage est réduit lors d'une impression offset à bobines et à sécheurs. En même temps, le phénomène de "cloquage" est éliminé et le contraste et la reproduction de couleur de l'empreinte sont améliorés.
PCT/FI2016/050546 2015-07-28 2016-07-28 Procédé pour éliminer l'humidité de voiles fibreux WO2017017316A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FI20155568A FI20155568A (fi) 2015-07-28 2015-07-28 Menetelmä kuituradan kosteuden poistamiseksi
FI20155568 2015-07-28

Publications (1)

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WO2017017316A1 true WO2017017316A1 (fr) 2017-02-02

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Application Number Title Priority Date Filing Date
PCT/FI2016/050546 WO2017017316A1 (fr) 2015-07-28 2016-07-28 Procédé pour éliminer l'humidité de voiles fibreux

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FI (1) FI20155568A (fr)
WO (1) WO2017017316A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109774333A (zh) * 2019-01-10 2019-05-21 安徽省阜阳市国泰彩印包装有限公司 一种彩印包装固化方法

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1990007027A1 (fr) * 1988-12-22 1990-06-28 Sulzer-Escher Wyss Gmbh Procede pour lisser une bande de papier
US6207020B1 (en) * 1998-05-12 2001-03-27 International Paper Company Method for conditioning paper and paperboard webs
WO2005053958A1 (fr) * 2003-12-03 2005-06-16 Goss Contiweb B.V. Presse rotative alimentee par bande et procede permettant de minimiser le rainurage dans une presse rotative alimentee par bande
DE102005059734A1 (de) * 2005-12-14 2007-06-28 Voith Patent Gmbh Feuchtequerprofilsteuerung
EP2682520A1 (fr) * 2012-07-03 2014-01-08 Metso Paper Inc. Procédé de production d'une bande fibreuse et ligne de production d'une bande fibreuse
EP2876206A1 (fr) * 2013-11-21 2015-05-27 Valmet Technologies, Inc. Procédé de production de bandes de fibres et ligne de fabrication de bandes de fibres
EP3012371A1 (fr) * 2014-10-21 2016-04-27 Valmet Technologies, Inc. Procédé de traitement d'une bande de matière fibreuse et calandre de pour traiter une bande de matière fibreuse

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1990007027A1 (fr) * 1988-12-22 1990-06-28 Sulzer-Escher Wyss Gmbh Procede pour lisser une bande de papier
US6207020B1 (en) * 1998-05-12 2001-03-27 International Paper Company Method for conditioning paper and paperboard webs
WO2005053958A1 (fr) * 2003-12-03 2005-06-16 Goss Contiweb B.V. Presse rotative alimentee par bande et procede permettant de minimiser le rainurage dans une presse rotative alimentee par bande
DE102005059734A1 (de) * 2005-12-14 2007-06-28 Voith Patent Gmbh Feuchtequerprofilsteuerung
EP2682520A1 (fr) * 2012-07-03 2014-01-08 Metso Paper Inc. Procédé de production d'une bande fibreuse et ligne de production d'une bande fibreuse
EP2876206A1 (fr) * 2013-11-21 2015-05-27 Valmet Technologies, Inc. Procédé de production de bandes de fibres et ligne de fabrication de bandes de fibres
EP3012371A1 (fr) * 2014-10-21 2016-04-27 Valmet Technologies, Inc. Procédé de traitement d'une bande de matière fibreuse et calandre de pour traiter une bande de matière fibreuse

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109774333A (zh) * 2019-01-10 2019-05-21 安徽省阜阳市国泰彩印包装有限公司 一种彩印包装固化方法

Also Published As

Publication number Publication date
FI20155568A (fi) 2017-01-29

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