EP0752322B1 - Impression lithographique avec plaques en polyester ainsi que système de montage sur cylindres d'imprimerie - Google Patents

Impression lithographique avec plaques en polyester ainsi que système de montage sur cylindres d'imprimerie Download PDF

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Publication number
EP0752322B1
EP0752322B1 EP19950202360 EP95202360A EP0752322B1 EP 0752322 B1 EP0752322 B1 EP 0752322B1 EP 19950202360 EP19950202360 EP 19950202360 EP 95202360 A EP95202360 A EP 95202360A EP 0752322 B1 EP0752322 B1 EP 0752322B1
Authority
EP
European Patent Office
Prior art keywords
printing plate
lithographic printing
adhesive
plate
polyester film
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.)
Expired - Lifetime
Application number
EP19950202360
Other languages
German (de)
English (en)
Other versions
EP0752322A2 (fr
EP0752322A3 (fr
Inventor
Antoine c/o Agfa-Gevaert N.V. De Jaeger
Georges Barnicle
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.)
Agfa Gevaert NV
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Agfa Gevaert NV
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Filing date
Publication date
Application filed by Agfa Gevaert NV filed Critical Agfa Gevaert NV
Priority to EP19950202360 priority Critical patent/EP0752322B1/fr
Publication of EP0752322A2 publication Critical patent/EP0752322A2/fr
Publication of EP0752322A3 publication Critical patent/EP0752322A3/fr
Application granted granted Critical
Publication of EP0752322B1 publication Critical patent/EP0752322B1/fr
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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41F—PRINTING MACHINES OR PRESSES
    • B41F27/00—Devices for attaching printing elements or formes to supports
    • B41F27/12—Devices for attaching printing elements or formes to supports for attaching flexible printing formes
    • B41F27/1262—Devices for attaching printing elements or formes to supports for attaching flexible printing formes without tensioning means
    • B41F27/1275—Devices for attaching printing elements or formes to supports for attaching flexible printing formes without tensioning means by means of adhesives, staples
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41N—PRINTING PLATES OR FOILS; MATERIALS FOR SURFACES USED IN PRINTING MACHINES FOR PRINTING, INKING, DAMPING, OR THE LIKE; PREPARING SUCH SURFACES FOR USE AND CONSERVING THEM
    • B41N6/00—Mounting boards; Sleeves Make-ready devices, e.g. underlays, overlays; Attaching by chemical means, e.g. vulcanising
    • B41N6/02—Chemical means for fastening printing formes on mounting boards

Definitions

  • the present invention relates to a method for mounting a lithographic printing plate carrying a lithographic image on a polyester film support on a plate cylinder of a web press.
  • the present invention further relates to a polyester based lithographic printing plate that is appropriately prepared for mounting on a web press.
  • the present invention concerns a device for preparing a polyester based lithographic printing plate for mounting on a plate cylinder of a web press.
  • a typical web press has a plate cylinder 10 including a reel bar 120.
  • a metal lithoplate 14 Before being mounted, a metal lithoplate 14 is bent so that its lead edge fits over the leading edge or "bullnose" 16 of the plate cylinder and its trailing edge fits into a slot 18 of the reel bar 120.
  • the reel bar is then cranked clock-wise (as seen in Fig. 1) until the plate fits tightly against the surface of the plate cylinder.
  • To remove the lithoplate requires counter clockwise cranking of the reel bar.
  • a skilled operator will be able to remove one plate and mount another in about one minute. Printing presses of this type are available from Harris Graphics, American Type Founders, Geo. Hantscho CO. Inc., and Timpsons Ltd..
  • this type of printing press is used to print with metal plates having a thickness of about 0.3mm.
  • a paper or plastic underpacking To the underside of the plates base may be adhered a paper or plastic underpacking, the thickness of which is selected to provide the desired interference between the printing plate and the blanket cylinder, usually about 0.1mm.
  • US-A-4.643.093 describes a polyester based lithographic printing plate that is double bended near its lead edge and that has been provided with an adhesive at the backside of the plate near its trailing edge . Between the two bends, a stiffener is fitted. The bended portion and stiffener are inserted in the longitudinal channel of the plate cylinder and the plate is wrapped around the plate cylinder. The trailing edge is adhered to the plate cylinder by pressing the trailing edge towards the plate cylinder.
  • Adhesive means to attach printing plate to plate cylinder are described in EP-A-449 131.
  • a machine for bending, cutting and punching metal printing plates is described in US-A-3 755 627.
  • the printing plate is first bendt near its lead edge parallel to registration-line openings.
  • the printing plate is also trimmed to an appropriate length of the printing plate between bend and trailing edge that is between a size corresponding to the circumference of the plate cylinder minus the length of the arc corresponding to the mounting channel and a size corresponding to the circumference of the plate cylinder.
  • bending and trimming is performed in an accurate and convenient way using a bender in accordance with the present invention.
  • Fig. 2 there is shown a schematic cross-sectional view of a bender according to a particular embodiment of the present invention.
  • the polyester based lithographic printing plate 25 is put on the surface of bender bars 61 and 62 and is pushed against a pair of stops 12.
  • the printing plate has notches in which stops 12 can be fitted. Stops 12 each have a micrometer adjustment in the direction of movement of the bender bar 62.
  • stops 12 are mounted on a slide bar 70 movable in an inverted T-shaped guideway in the bender bar 62.
  • a fixed barrel 71 has an opening to receive a projection from the bar 70 which is joined to the end of the adjusting screw 73 of the micrometer.
  • a set screw 72 will set the position of the bar 70 once established.
  • the printing plate is cut to an appropriate length by moving knife 40 downwardly.
  • the bender includes a bar 41 to hold the printing plate firmly down during cutting.
  • Bender bars 61 and 62 are at an elavated temperature, typically around 65°C.
  • An elongated blade 60 is moved downwardly to force the printing plate between the bender bars against bender bar surface 64.
  • bender bar 62 is moved towards bender bar 61 to create a force concentrated in the region of the bend.
  • the bender bar is then retracted and blade 60 is moved back upwardly.
  • a band of adhesive typically between 1 and 10cm but preferably between 1 and 5cm, is provided on the back side, i.e. the side opposite to that containing the lithographic image, of the printing plate near the leading edge as well as near the trailing edge.
  • a side view of such a printing plate is shown in Fig. 3.
  • Fig. 3 shows two bands of adhesive 22 and 23 respectively near the lead edge having a bend 90 and near the trailing edge of the printing plate.
  • the short edge 91 of bend 90 preferably has a length between 1 and 3cm.
  • the adhesive to be used in connection with the present invention will be a low-tack repositionable pressure-sensitive adhesive such as e.g. SPRAY-MOUNTTM or Crown adhesive 8091NTM.
  • Fig. 4 there is shown a printing plate mounted in accordance with the present invention. As illustrated, the lead edge 91 of the bend is inserted into the longitudinal channel of the plate cylinder 10 and fitted over the leading edge or "bullnose" 16 thereof. Adhesive bands 22 and 23 are provided between the printing plate and the surface of the plate cylinder which is preferably provided with an underpacking (not shown). It can further be seen that reel bar 120 is not used.
  • the polyester film support of the lithographic printing plate in connection with this invention has a thickness of 0.1mm to 0.35mm and an Young modulus of at least 4300N/mm 2 .
  • the Young-modulus also called E-modulus in connection with the present invention can be measured according to method A of the ANSI-D882-91 standard.
  • At least one of the two main directions of orientation of the polyester film i.e. the machine direction (longitudinal direction) or the direction perpendicular thereto (transverse direction) should have an E-modulus of at least 4300 N/mm 2 .
  • the polyester film support is isotropic in the E-modulus i.e. the ratio of E-modulus in longitudinal direction to the transverse direction is between 0.8 and 1.3.
  • the use of an isotropic polyester film support offers the advantage that when the plate is turned 90° the same printing properties are obtained so that manufacturing of different sizes of the printing plates out of a master roll is simplified.
  • Such isotropic supports also offer an advantage when the imaging element is to be used in an image-setter for high intensity short time exposure.
  • several images on one printing plate may be oriented parallel and/or perpendicular to the axis of the printing cylinder in the printing machine.
  • an isotropic polyester film support it will be much easier to obtain a steady print.
  • an anisotropic polyester film support when used a larger E-modulus can be obtained because a large E-modulus in one direction generally goes to the detriment of the E-modulus in the direction perpendicular thereto.
  • such printing plate In order to obtain the benefit of an anisotropic polyester film support, such printing plate should be mounted with its E-modulus of more than 4300 N/mm 2 perpendicular to the axis of the printing cylinder of the printing press.
  • the polyester film in accordance with the present invention is preferably a polyethylene terephthalate film although other polyester films may also be used in accordance with the present invention.
  • the polyester film in accordance with the present invention may be uniaxially oriented but is preferably biaxially oriented.
  • the desired E-modulus may be obtained by setting the degree of orientation of the polyester film.
  • the degree of orientation is obtained by stretching the polyester film in the longitudinal and/or transverse direction with a factor between 1:2 to 1:4.
  • the E-modulus may further be influenced by adding substances to the polyester film such as e.g. low molecular weight compounds, voiding agents such as e.g. BaSO 4 , polypropylene and opacifying agents such as e.g. TiO 2 .
  • substances to the polyester film such as e.g. low molecular weight compounds, voiding agents such as e.g. BaSO 4 , polypropylene and opacifying agents such as e.g. TiO 2 .
  • the polyester film support in accordance with the present invention is preferably coated with a layer improving the adhesion of the hydrophilic layers.
  • Examples of lithographic printing plates carrying a lithographic image on a polyester support can be produced from imaging elements that may be photosensitive or that may be imaged in other ways such as e.g. by means of heat.
  • a particular example of such an imaging element comprises on a polyester film support in the order given a silver halide emulsion layer (photosensitive layer) and a layer containing physical development nuclei. After image-wise exposure to e.g. visible light or infrared light, the imaging element is developed in a processing liquid according to the silver salt diffusion transfer process to obtain a lithographic printing plate.
  • Such type of printing plates are known as photodirect printing plates because the paste-up can immediately be copied onto the imaging element without the need for intermediate films.
  • a particular interesting variant of this type of printing plates is produced by exposing the imaging element with a laser or laser-diode under the control of a computer.
  • the latter exposure is generally performed by mounting the imaging element on a drum in image setter.
  • the laser beam then scans over the drum and writes the digital image-data received from a computer while the drum rotates.

Claims (9)

  1. Procédé de montage d'une plaque d'impression lithographique portant une image lithographique sur un support en film de polyester présentant une épaisseur comprise entre 0,1 mm et 0,35 mm et un module de Young d'au moins 4300 N/mm2, sur un cylindre-plaque d'une rotative, ledit cylindre-plaque présentant un canal destiné à recevoir le bord avant de la plaque d'impression lithographique, et ledit procédé comprenant les étapes consistant à :
    (1) plier la plaque d'impression lithographique le long d'une ligne parallèle à des ouvertures de ligne de repère près de son bord avant et perpendiculaire à un sens d'orientation dudit film de polyester dont le module de Young est d'au moins 4300 N/mm2 ;
    (2) appliquer un adhésif sur le dos de la plaque d'impression lithographique au moins près de oses bord avant et bord arrière ;
    (3) insérer le bord avant dans un canal longitudinal du cylindre-plaque et ;
    (4) enrouler la plaque d'impression lithographique autour du cylindre-plaque tout en pressant l'adhésif contre le cylindre-plaque.
  2. Procédé selon la revendication 1, dans lequel la longueur de ladite plaque d'impression lithographique entre la pliure et le bord arrière est comprise entre une dimension correspondant à la circonférence dudit ' cylindre-plaque moins l'arc correspondant à l'ouverture du canal de montage et une dimension correspondant à la circonférence du cylindre-plaque.
  3. Procédé selon la revendication 1, dans lequel ledit adhésif est un adhésif sensible à la pression, repositionnable et peu collant.
  4. Procédé selon la revendication 1, dans lequel ledit adhésif est appliqué près des bords avant et arrière de la plaque d'impression lithographique, dans une bande d'une largeur comprise entre 1 et 5 cm.
  5. Procédé selon la revendication 1, dans lequel ladite pliure présente un angle compris entre 30° et 60°.
  6. Plaque d'impression lithographique portant une image lithographique sur un support en film de polyester présentant une épaisseur comprise entre 0,1 mm et 0,35 mm et un module de Young d'au moins 4300 N/mm2 et comportant un bord avant et un arrière, ladite plaque d'impression lithographique étant pliée perpendiculairement au sens d'orientation dudit film de polyester dont le module de Young est d'au moins 4300 N/mm2 et parallèlement et à côté de son bord avant selon un angle inférieur à 90°, le dos de ladite plaque d'impression lithographique étant pourvu d'un adhésif au moins près des bords avant et arrière.
  7. Plaque d'impression lithographique selon la revendication 6, dans laquelle la pliure présente un angle compris entre 30° et 60°.
  8. Plaque d'impression lithographique selon la revendication 6, dans laquelle ledit adhésif est un adhésif sensible à la pression, repositionnable et peu collant.
  9. Appareil à plier destiné à plier une plaque d'impression lithographique portant une image lithographique sur un support en film de polyester, ledit appareil à plier comprenant des barres de pliage (61) et (62), une lame allongée (60) et une butée de positionnement (12), ledit appareil à plier comprenant en outre un moyen de coupe (40) destiné à couper ladite plaque d'impression lithographique à une longueur appropriée.
EP19950202360 1995-07-07 1995-09-01 Impression lithographique avec plaques en polyester ainsi que système de montage sur cylindres d'imprimerie Expired - Lifetime EP0752322B1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP19950202360 EP0752322B1 (fr) 1995-07-07 1995-09-01 Impression lithographique avec plaques en polyester ainsi que système de montage sur cylindres d'imprimerie

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
EP95201856 1995-07-07
EP95201856 1995-07-07
EP19950202360 EP0752322B1 (fr) 1995-07-07 1995-09-01 Impression lithographique avec plaques en polyester ainsi que système de montage sur cylindres d'imprimerie

Publications (3)

Publication Number Publication Date
EP0752322A2 EP0752322A2 (fr) 1997-01-08
EP0752322A3 EP0752322A3 (fr) 1998-07-15
EP0752322B1 true EP0752322B1 (fr) 2001-06-27

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP19950202360 Expired - Lifetime EP0752322B1 (fr) 1995-07-07 1995-09-01 Impression lithographique avec plaques en polyester ainsi que système de montage sur cylindres d'imprimerie

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Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE795572A (fr) * 1972-02-29 1973-06-18 Grace W R & Co Dispositif pour poinconner, et ebarber de facon precise une plaque d'impression
US4643093A (en) 1985-03-01 1987-02-17 Minnesota Mining And Manufacturing Company Double-creased lithoplate and method of mounting on a web press
DE4009649A1 (de) * 1990-03-26 1991-10-02 Koenig & Bauer Ag Verfahren und vorrichtung zur druckplattenbefestigung
JPH03294376A (ja) * 1990-04-12 1991-12-25 Lintec Corp 印刷ロール及び印刷ロール用粘着シート
JP2700951B2 (ja) * 1990-12-20 1998-01-21 アグファ−ゲヴェルト ナームロゼ ベンノートチャップ 平版印刷版用原版

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Publication number Publication date
EP0752322A2 (fr) 1997-01-08
EP0752322A3 (fr) 1998-07-15

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