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DE-102013110450-B4 - Sheet-fed rotary offset printing press with equipment for drying radiation-curing special inks

DE102013110450B4DE 102013110450 B4DE102013110450 B4DE 102013110450B4DE-102013110450-B4

Abstract

Sheet-fed printing press for single- or multi-color printing of printing inks onto printed sheets, comprising a feeder (1), one or more printing units (2, 3, 4, 5, 11) for applying special printing inks to a substrate, incorporating an inking/moistening unit, a plate cylinder (P), a rubber cylinder (G) and an impression cylinder (D) in each printing unit (2, 3, 4, 5, 11), wherein the special printing inks are mixed with photoinitiators and are suitable for curing by means of UV radiation, with a delivery conveyor (8) and a delivery unit (10) receiving a stack of sheets, characterized in that that in the area directly after a last printing unit (5, 11) suitable for printing a special printing ink, at least one first emitter device (13, 14) is provided on the printed side of the printed sheets for introducing heat energy into the printing ink layer on the printed sheets. and that on the conveying path of the boom conveyor (8) to the boom (10) at a distance in the sheet travel direction of at least the length of a printed sheet from the position of the first radiation device (13, 14) a second radiation device (12) for applying radiation that triggers the hardening of the printing ink layer on the printed sheet is arranged, wherein the first emitter device (13, 14) on the conveying path of the boom conveyor (8) or the counter-pressure cylinder (D) of the last printing unit (5, 11) is designed as a thermal air blowing device (14) for applying a heated air stream to the ink layer on the freshly printed sheet.

Inventors

  • Stefan Vogel
  • Thomas Klassert

Assignees

  • manroland sheetfed GmbH

Dates

Publication Date
20260513
Application Date
20130920

Claims (8)

  1. Sheet-fed printing press for single- or multi-color printing of printing inks onto printed sheets, comprising a feeder (1), one or more printing units (2, 3, 4, 5, 11) for applying special printing inks to a substrate, incorporating an inking/moistening unit, a plate cylinder (P), a rubber cylinder (G), and an impression cylinder (D) in each printing unit (2, 3, 4, 5, 11), wherein the special printing inks are mixed with photoinitiators and are suitable for curing by means of UV radiation, a delivery conveyor (8), and a delivery (10) for receiving a stack of sheets, characterized in that, in the area directly after a last printing unit (5, 11) suitable for printing a special printing ink, at least one first emitter device (13, 14) for introducing heat energy into the printing ink layer on the printed sheet is provided on the printed side of the printed sheets, and that on the delivery path of the A second radiation device (12) for applying radiation that triggers the hardening of the printing ink layer on the printing sheet is arranged on the conveying path of the cantilever conveyor (8) to the cantilever (10) at a distance in the sheet travel direction of at least the length of a printed sheet from the position of the first radiation device (13, 14), wherein the first radiation device (13, 14) is designed as a thermal air blowing device (14) for applying a heated air stream to the ink layer on the freshly printed printed sheet.
  2. Sheet-fed printing press Claim 1 , characterized in that the first emitter device in the area of the last printing unit (5, 11) is assigned to a sheet-guiding counter-pressure cylinder (D) after its printing gap with a rubber cylinder (G) or that the first emitter device is assigned in or near the infeed area of the printed sheets to the boom conveyor (8) directly following the last printing unit (5, 11) and in the area of the boom conveyor (8) and that the first emitter device on the conveying path is assigned to the printed printed sheets on their printed side.
  3. Sheet-fed printing press Claim 1 or 2 , characterized in that the first emitter device consists of one or more modules, wherein the multiple modules are arranged to be operated individually or as variably switchable groups, wherein IR emitter devices (13) can be operated separately or together with thermal air blowing devices (14) or thermal air blowing devices (14) can be operated separately or together with IR emitter devices (13).
  4. Sheet-fed printing press according to one or more of the Claims 1 until 3 , characterized in that the second emitter device is arranged on the conveying path of the boom conveyor (8) in an area in front of or near the boom (10) and is designed as a UV emitter device (12) which is arranged to consist of one or more UV emitters.
  5. Sheet-fed printing press Claim 4 , characterized in that a maximum dry section (9) is formed between the first module of the first emitter device and the last module of the second emitter device on the conveying path of the boom conveyor (8).
  6. Sheet-fed printing press according to one or more of the Claims 1 until 5 , characterized in that the modules (13, 14) of the first emitter device and the UV emitters (12) of the second emitter device are arranged in such a coordinated and switchable manner that a drying path (9A) adapted to the substrate, ink and drying requirements is provided between the last IR emitter (13) or the last thermal air blowing device (14) in the direction of the sheet travel and the first UV emitter (12) of the second emitter device in the direction of the sheet travel to the boom (10).
  7. Method for operating a sheet-fed printing press for single- or multi-color printing of printing inks onto printing sheets with a feeder (1), with one or more printing units (2, 3, 4, 5, 11) when applying special printing inks to a substrate, incorporating an inking/moistening unit, a plate cylinder (P), a rubber cylinder (G), and an impression cylinder (D) in each printing unit (2, 3, 4, 5, 11), wherein the special printing inks are mixed with photoinitiators and suitable for curing by means of UV radiation, with a delivery conveyor (8) and a delivery unit (10) for receiving a stack of sheets, and with radiant devices in the area of the delivery conveyor (8) for drying a color image, comprising the following steps: - a single- or multi-color printed image is applied to a printing sheet by means of the printing units (2, 3, 4, 5, 11), - no drying of the color image on the printing sheet takes place Further coating of the print, - one or all of the special printing inks of the color image on the printed sheet are heated by means of a first radiation device, - the printed sheet is transported in the heated state over at least one sheet length without further radiation treatment, - one or all of the special printing inks of the printed image are subjected to a radiation treatment curing the special printing inks by means of a second radiation device, and - the printed sheet is laid out on a sheet stack in the delivery unit (10) with the special printing inks fully cured, whereby when using several modules of the first radiation device as IR radiation devices (13) and/or thermal air blowing devices (14) and the second radiation device as a UV radiation device (12), the modules of the first and second radiation devices are switched depending on the print subject in such a way that sufficient curing of the special printing inks for the intended further processing of the printed sheets results from sufficient heating of the color image, sufficient waiting time before the curing treatment and sufficient exposure to the hardening radiation is present.
  8. Procedure according to Claim 7 , characterized in that the printed sheet with a printed image made of special printing inks is treated after the last printing unit (5, 11) by means of a radiation treatment using at least one IR emitter device (13) and/or a thermal air blowing device (14) and that after a waiting period during the further transport of the printed sheet by means of the boom conveyor (8) the printed sheet is treated by means of a UV emitter device (12) to completely cure the special printing inks in the color image on the printed sheet.

Description

The invention relates to a sheet-fed rotary offset printing machine with facilities for drying uncoated multicolor prints. It is known to apply a fast-drying coating, such as a varnish, to printed sheets after printing a multi-colored image in order to protect the ink surface which has not yet hardened. UV-reactive inks are also used to produce fast-drying ink layers. These inks cross-link after exposure to UV light, instantly creating a dry surface. However, because these inks do not continue to dry on the substrate like conventional offset inks, complete cross-linking of the ink layers is essential. Otherwise, the resulting printed product would be entirely unusable. In the US 2002/0178944 A1 A rotary printing press with an integrated coating unit is disclosed. The integration of coating units into rotary printing presses makes it possible, in a manner known per se, to achieve special printing effects, particularly gloss effects, on a substrate. When processing substrates with integrated coating units, specific adjustments to the printing speed are necessary to ensure sufficient drying of the coating before the substrate, especially a sheet, enters a subsequent printing unit or a sheet delivery system. Out of DE 10 2008 014 269 A1 A method and a device for radiation curing a coating on a substrate are known. The coating is irradiated with UV light by at least one UV lamp at an irradiation location for an irradiation duration that may be defined by a relative movement of the substrate. An inert gas is supplied by a gas supply device to reduce the negative effects of oxygen on the coating. The inert gas is supplied only during part of the irradiation duration, and the inert gas supply is interrupted during the remaining part of the irradiation duration. Out of DE 10 2006 032 831 A1 A drying device for treating a substrate surface in a processing machine is known. This drying device is improved such that the proportion of infrared (IR) radiation emitted by a radiation unit can be reduced from the total radiation energy directed at the substrate using simple means. For this purpose, the reflector of the drying device has a dichroic layer on its front surface facing the radiation unit and a first IR absorber layer on its back surface. From the EP 1671788 B1 A rotary printing press with an integrated coating unit is known. In the rotary printing press, a radiation device is provided in a sheet exit section downstream of the printing nip in the sheet travel direction. This device serves to irradiate the coating applied to the substrate with coating-curing and/or coating-drying radiation immediately after the sheet exits the printing nip. In a section of the printing cylinder assembly downstream of the radiation device in the sheet travel direction, a blowing device for blowing conditioned air onto the irradiated coating is arranged parallel to the printing cylinder assembly. This makes it possible to initiate and pre-cure the drying or curing process of the varnish transferred to the substrate immediately after the substrate exits the printing nip. Further drying or curing can then take place within the same cylinder quadrant by applying conditioned air. The wavelength of this radiation is preferably in the range of 350 nm to 4000 nm, particularly in the range of 700 nm to 4000 nm. The air is preferably conditioned to a specified humidity/temperature condition. The emitter can be an IR cold radiator or combined with a UV radiator. The intensity of the radiation applied to the substrate by the IR cold radiator can be adjustable. Preferably, the temperature of the air supplied by the air-jet nozzle assembly is also adjustable. This makes it possible to control the amount of heat introduced or, if necessary, dissipated by the air supply to the varnish or the substrate. It is possible to combine the blowing device and the IR cold radiator into a drying module or assembly. The blowing device and the IR cold radiator are preferably arranged so compactly that irradiation and air exposure occur at an angle of less than 45° on the printing cylinder. Such a compact arrangement of a paint drying unit can advantageously be positioned in the circumferential area of the printing cylinder located between the printing gap and the transfer area to the transfer cylinder. It is still known that special UV-reactive inks can be used to produce fast-drying printed products. However, in addition to the very high energy consumption and environmental concerns regarding their use, such as ozone production, the question of further processing such products is not sufficiently resolved. In most cases, treating the printed images with UV lamps is insufficient to achieve a durable and therefore abrasion-resistant ink surface, and thus a suitable ink application for further processing in a reliably controllable process. Furthermore, the use of special UV lamps to improve the curing of the ink layers only achieves an unsatisfactory gloss result