EP3917780B1 - Method and printing machine respectively for printing a metallic printable material - Google Patents

Description

The invention relates to a method for printing a metallic printing material according to the preamble of claim 1 and a printing press according to the preamble of claim 6 for carrying out the aforementioned method.

through the U.S. 2018/0046114 A1 a device for applying a decoration to an outer surface of a metallic container is known, comprising a transfer printing forme, an electrophotographic system in a predetermined orientation with respect to the transfer printing forme, the electrophotographic system conveying a toner material onto the transfer printing forme, and a feed unit to bringing the metallic container into contact with the transfer printing form to transfer the toner material from the transfer printing form to the outer surface of the metallic container for the decoration thereof.

through the US 2017/0354991 A1 a method for producing a steel plate printed with a transparent pattern is known, comprising forming a printed ink film layer by ejecting transparent ink onto at least one surface of a steel plate and curing the printed ink film layer with ultraviolet light to form a cured printed ink film layer, and further preferably comprising performing a pre-processing on the relevant surface of the steel plate with plasma before forming the printed ink film layer.

through the DE 10 2006 044 957 A1 is a method for the transfer of imaging and / or covering or overlaying application layers from a transfer film to printed sheets in a sheet-processing machine, in particular a sheet-fed rotary printing press, is known, at least with an application unit for a Image-wise or two-dimensional coating of a printing sheet with an adhesive and with at least one coating unit for transferring image-forming or covering layers from the transfer film to the printing sheet, with a transfer gap being formed in a coating unit and the transfer film along the surface of a press roller and with the coated side on placed on a printing sheet and can be guided under pressure together with this through the transfer gap, so that the imaging or covering layers are adhesively transferred from the transfer film to the printing sheet in areas provided with adhesive, with the printing press being supplied with stiff-elastic printing sheets as metal sheets or plastic sheets which are provided on at least one printed or coated or unprinted or uncoated first side in a transfer nip with an image-wise or full-surface film coating of the transfer film, and the metallic or w. Plastic printed sheets are dried before and/or after the application of the film coating.

through the DE 60 120 305 T2 method for printing a printing material made of sheet metal in a printing machine is known, in which a surface of the sheet metal on which the imprint has a layer thickness z. B. from 0.2 microns to 10 microns, is provided with a white coating.

through the EP 1 503 899 A2 discloses a device for printing essentially non-absorbent printing material in the form of metal panels, with a printing machine that belongs to a printing line and has at least one printing unit equipped with printing ink, with a first printing device and a second printing device being provided, each belonging to the printing line and to the The printing unit - as seen in the printing direction - is upstream, with the first printing device being followed by the second printing device as seen in the printing direction, and with the first printing device being equipped with a UV-drying primer and the second printing device being equipped with a UV-drying white lacquer and the first printing device and the a UV drying device belonging to the printing line is connected downstream of the second printing device.

through the EP 2 428 359 A1 discloses a printing device for printing flat structures with at least one printing ink, the surface tension of this flat structure being less than or equal to the surface tension of the printing ink, comprising at least one active printing unit and a final drying system downstream of this at least one active printing unit for drying the at least one active printing unit printing ink applied to the fabric, at least one irradiation device each having at least one electromagnetic radiation source for irradiating the fabric before it is fed to the at least one active printing unit is configured upstream of the at least one active printing unit, the radiation source e.g. B. is an elongated UV gas discharge tube or an elongated infrared radiator.

through the DE 10 2012 000 414 A1 a method for passivating the surface of tinned steel strip is known, with the steel strip being moved through a coating system at a strip speed of at least 200 m/min, with the surface being anodically oxidized after the steel strip has been tinned and a liquid solution of a chromium-free substance being applied to the oxide layer Aftertreatment agent is applied.

through the WO 2016/188 964 A1 a rotary printing machine is known, with a printing station for applying water-soluble printing ink to a plastic film and with a reaction chamber upstream of the printing station, in which the surface of the plastic film is modified by plasma treatment by means of a gas jet in such a way that the surface is coated with water-soluble printing ink can be printed without using a primer layer.

through the WO 2007/016 999 A2 a method is known for the continuous atmospheric pressure plasma treatment of in particular electrically insulating workpieces, in particular material plates or webs, in which a workpiece to be treated at a distance below one of at least two arranged one behind the other in the direction of movement, leaving a gap, extends transversely to the direction of movement at least over the The electrode and the workpiece are set in motion relative to one another in a direction of movement, with a high voltage in the form of an alternating voltage being applied to the barrier electrodes in order to ignite a plasma discharge at least in the gap and wherein the plasma discharge is driven out of the gap in the direction of the surface of the workpiece to be treated by means of a gas flow, the surface of the workpiece to be treated facing the surface n of the barrier electrodes are subjected to the high voltage, as a result of which, due to the plasma gas flowing out of the gap and flowing into the area between the barrier electrodes and the surface of the workpiece to be treated, the ignition voltage is reduced for igniting a between the surfaces of the barrier electrodes facing the workpiece and the to treated surface of the workpiece is reached and thus a plasma acting over the entire width of the workpiece is ignited.

through the EP 0 761 415 A2 a method for surface pretreatment of workpieces by means of electrical discharge is known, a focused jet of a reactive medium being produced by plasma discharge with the supply of a working gas and the surface of the workpiece to be treated being swept with this jet.

The invention is based on the object of creating a method for printing a metallic printing material and a printing machine for carrying out the aforementioned method, with wetting properties of the surface of the printing material for the printing ink to be applied to it or the lacquer to be applied to it can be improved and/or an improved adhesive bond is produced between the metallic printing material and the printing ink or lacquer to be applied to the surface of this printing material.

The object is achieved according to the invention by a method having the features of claim 1 and/or by a printing machine having the features of claim 6 . The respective dependent claims relate to advantageous refinements and/or developments of the solution found.

The advantages that can be achieved with the invention are, in particular, that wetting properties of the surface of the printing material for the printing ink to be applied to it or the coating to be applied to it are improved and/or an improved adhesive bond between the metallic printing material and the printing ink to be applied to the surface of this printing material or the coating to be applied paint is produced. With the proposed solution, it is possible that an original in terms of its surface, ie non-processed metallic printing material with a chrome-containing surface, preferably a z. B. tinned and chrome-passivated sheet metal or a chrome-plated sheet metal, in particular a tinplate, can be printed directly, ie without performing an additional processing step preceding the printing, namely the application of a primer. Since the plasma pre-treatment takes place inline in the printing machine, the plasma pre-treatment of the surface to be printed on the metallic substrate and its printing and, if necessary, painting are carried out in one and the same machine pass, which means that complex intermediate steps such as e.g. B. an intermediate storage or relocation of the printing material in question and / or the provision of several different separate production lines can be avoided.

An embodiment of the invention is shown in the drawings and is described in more detail below.

Fig. 1

Eine Druckmaschine zum Bedrucken eines metallischen Bedruckstoffes mit einer dem mindestens einen Druckwerk vorgeordneten Plasmavorbehandlungseinrichtung ;

Fig. 2

die Plasmavorbehandlungseinrichtung der Fig. 1 in einer quer zur Transportrichtung des Bedruckstoffes gerichteten Ansicht.

Show it:

1

A printing machine for printing a metallic printing material with a plasma pretreatment device arranged upstream of the at least one printing unit;

2

the plasma pretreatment facility 1 in a view directed transversely to the transport direction of the printing material.

Sheet metal is a flat rolled finished product made of metal, e.g. B. is delivered as a sheet or as a steel strip roll (coil). The format of rectangular metal sheets, ie their edge lengths, is z. B. in the range between 500 mm x 700 mm and 1,000 mm x 1,200 mm. The following preferably relates to the printing of a surface of a tinplate, with a tinplate having a thin, cold-rolled steel plate as the body plate, the surface of which is preferably coated with tin. Tinplate thicknesses of 0.1 mm to 0.5 mm are currently common. The main purpose of tinning is to protect against corrosion. To carry out the method according to the invention, a tinned, chrome-surface- passivated ETP sheet ( electrolytic tin plate) or a chrome- plated ECCS sheet (electrolytic chrome coated steel ) is preferably used. In principle, a printing material designed as a hollow body can also be used, provided that this also has a chrome-containing surface and a printing ink that hardens by exposure to ultraviolet radiation and/or a lacquer that hardens by exposure to ultraviolet radiation is applied to this surface in a printing press will or will

To decorate a training z. B. a packaging sheet metal used are a mostly viscous ink or a mostly low-viscosity paint each in a layer thickness z. B. from 1 micron to 10 microns, preferably applied in a layer thickness in a range between 4 microns and 5 microns on the bare chromium-containing surface of the sheet in question through the use of at least one printing unit of a printing press, directly and directly, ie without the additional processing step, to be carried out before printing, of applying a primer to the chrome-containing surface in question.

Printing inks are i. i.e. R. liquid mixtures of substances and consist of dispersed, d. H. from i. i.e. R. extremely finely divided pigments, binders and organic solvents. Black ink contains carbon black pigments, especially carbon black. Colored pigments are extracted from minerals or chemically produced.

The mechanical properties of printing inks are also called rheological properties. Printing inks for printing processes in which the ink is applied by rollers, e.g. B. in offset printing, letterpress or gravure printing, require good transport of the ink over the ink rollers and low aerosol formation. Ink transport is determined by the tack of the printing ink. Tack is the force required to separate an ink film. It is a complex relationship between viscosity, cohesion and adhesion and is measured in printing ink testing as what is known as "tack". Aerosol formation is the formation of ink mist and filaments of ink at high print speeds. These aerosols are undesirable. The formation of aerosols is strongly dependent on the temperature, since it correlates directly with the viscosity.

1. a) Farbmitteln, d. h. aus Pigmenten oder Farbstoffen, für die Farbigkeit,
2. b) Bindemitteln, hauptsächlich aus Harzen (Festharze, Alkydharze), um die Farbmittel auf dem Bedruckstoff zu befestigen,
3. c) Hilfsstoffen zum Einstellen der rheologischen Eigenschaften, z. B. zur Beeinflussung von Trocknung, Glanz oder Oberflächenhärte.

Printing inks consist of:

1. a) colorants, i.e. made of pigments or dyes, for the color,
2. b) binders, mainly made of resins (solid resins, alkyd resins) to attach the colorants to the substrate,
3. c) auxiliaries for adjusting the rheological properties, e.g. B. to influence drying, gloss or surface hardness.

Paint is a liquid or powdered coating material that is applied thinly to an object and built up into a continuous, solid film through chemical or physical processes that particularly affect its solvent. Varnishes consist i. i.e. R. from binders, fillers, pigments, solvents, resins and / or acrylates and additives such as biocides. In the case of an emission-free, in particular radiation-curing paint, a monomer serves as a "solvent" which polymerizes into the paint film during curing. It is a low-molecular binder with low vapor pressure, which is e.g. B. hardens chemically within fractions of a second. The source of radiation is i. i.e. R. a high-power UV lamp.

For applying the ink or the paint is z. B. a printing method using a printing form. In particular, the chromium-containing surface of the metallic printing material, i. H. of the sheet metal, in an offset printing process or in a relief printing process or in a flexographic printing process. As an alternative or in addition to the aforementioned printing processes, the chromium-containing surface of the metallic printing material can also be printed using a digital printing process without a printing forme.

According to the invention, a radiation-curing, in particular UV-curing, printing ink or such a varnish is used as a printing fluid, ie as a printing ink or as a varnish. The printing ink or lacquer is preferably cured by irradiation with ultraviolet radiation directed onto the printing material from a radiation source, this radiation source emitting electromagnetic radiation in the wavelength range, in particular between 100 nm and 400 nm.

To improve the wetting properties of the chrome-containing surface of the printing material for the ultraviolet-curing printing ink to be applied to it or the ultraviolet-curing lacquer to be applied thereto and/or to improve the adhesive bond between the metallic printing material and the chrome-containing surface of this printing material applied printing ink or applied paint is proposed to expose the chromium-containing surface in the printing press before printing with the printing ink or paint under atmospheric pressure of a preferably continuous, so non-pulsed irradiation with an ionized process gas. In this case, oil-free compressed air from the atmosphere surrounding the printing press is preferably used as the process gas for treating the chrome-containing surface of the printing material. However, nitrogen or an inert gas such as e.g. B. argon or helium are each suitable from a foreign gas atmosphere. The process gas is z. B. excited by an electrical AC voltage preferably in the voltage range between 5 kV and 15 kV and / or a frequency in the range between 10 kHz and 100 kHz and thereby ionized.

By irradiating the chromium-containing surface of the printing material with the ionized process gas, carbon-containing compounds and/or other contaminants are each detached from this surface and volatilized, because this plasma treatment triggers an oxidation process with regard to these contaminants. By removing these impurities, the surface tension of the chromium-containing surface of the printing material increases and the wettability of this surface improves. Therefore, the chromium-containing surface of the printing material can be printed directly after the irradiation with the ionized process gas, i. H. it is not necessary to apply a primer to this surface before printing.

1 shows a printing press 01 for printing in a schematic and highly simplified manner a metallic printing material 02 with a chrome-containing surface and at least one printing unit 03; 05; 07; 09, preferably with a plurality of printing units 03; 05; 07; 09 and optionally at least one coating unit 11, with a plasma pretreatment device 13 being arranged upstream of the first printing unit 03 in the transport direction T of the printing material 02 in the printing press 01, i.e. inline. The transport direction T of the printing material 02 through the printing press 01 is in the 1 indicated by a directional arrow. The relevant printing unit 03; 05; 07; 09 is e.g. B. in an offset printing process or in a relief printing process or in a flexographic printing process or in a screen printing process or in a digital printing process. In the case of a plurality of printing units 03; 05; 07; 09 these can also e.g. B. be formed printing in different printing processes. Between adjacent printing units 03; 05; 07; 09 and after the last printing unit 09 in the transport direction T of the printing material 02 is preferably a dryer, in particular an intermediate dryer 04; 06; 08; 10, with which the printing ink applied immediately beforehand to the printing material 02 is cured by exposure to ultraviolet radiation. In particular, after the last printing unit 09 in the transport direction T of the printing substrate 02, a coating unit 11 can be provided, with which a coating that hardens by exposure to ultraviolet radiation is applied to the printing substrate 02. This coating is applied in a z. B. additional intermediate dryer 04; 06; 08; 10 or dried in a final dryer 12. Since a printing ink that cures by exposure to ultraviolet radiation or a coating that cures by exposure to ultraviolet radiation is applied to printing substrate 02, the dryer 04; ; 06; 08; 10; 12, ie the respective intermediate dryer 04; 06; 08; 10 or the final dryer 12 each have a radiation source with electromagnetic radiation in the wavelength range directed onto the chromium-containing surface of the metallic printing substrate 02 preferably between 100 nm and 400 nm.

If this printing press 01 is used to print a metal printing material 02 in the form of a panel, the metal panels i. i.e. R. separated from a stack 14 and successively to the plasma pretreatment device 13 and then to the respective printing units 03; 05; 07; 09 and/or the coating unit 11. For this purpose, the individual metal sheets are transported through the printing machine 01 with a transport device, preferably in a flat position, either in a gripper closure or on a suction belt. The printing press 01 is designed to B. several thousand metal sheets, z. B. to treat and print about four thousand metal sheets per hour. The metal sheets are transported at a transport speed in the range z. B. from 0.5 m / s to 2 m / s transported through the printing press 01.

The plasma pretreatment device 13 preferably has a nozzle array 15, with the nozzle array 15 both in the transport direction T of the printing material 02 ( 1 ) as well as across it ( 2 ) each has a plurality of nozzles 16, from each of which a flow of the ionized process gas directed onto the chromium-containing surface of the metallic printing substrate 02 continuously flows out or at least can flow out. This treatment of the chromium-containing surface of the metallic printing material 02 takes place under atmospheric pressure. The printing press 01 therefore does not require a separate reaction chamber with locks for the entry or exit of the printing material 02 into this reaction chamber. These locks would be required if z. B. is formed a negative pressure or an overpressure compared to the environment.

the 2 shows the plasma pretreatment device 13 of FIG 1 in a view directed transversely to the transport direction T of the printing material 02. There is a distance a between an outlet opening of the respective nozzle 16 for the respective flow of the ionized process gas and the chromium-containing surface of the metallic printing material 02 in an area e.g. B. between 5 mm and 50 mm. The nozzles 16 are each preferably arranged perpendicular to the transport direction T of the printing material 02. The nozzles 16 are arranged in such a way that metal sheets to be printed on by the printing machine 01 can be treated inline with the process gas by the plasma pretreatment device 13, preferably over the entire surface. However, it can also be provided that the nozzles 16 of the plasma pretreatment device 13, in particular of the nozzle array 15, are or are selectively used by a control unit, with the treatment of the sheet metal panels to be printed by the plasma pretreatment device 13 only taking place in previously selected areas.

Reference List

01

printing press

02

substrate

03

printing unit

04

intermediate dryer

05

printing unit

06

intermediate dryer

07

printing unit

08

intermediate dryer

09

printing unit

10

intermediate dryer

11

painting unit

12

final dryer

13

plasma pretreatment facility

14

stack

15

nozzle array

16

jet

a

Distance

T

transport direction

Claims (15)

1. A method for printing a metallic printable material (02) by means of a printing machine (01), wherein a printing ink and/or a lacquer is/are respectively applied to a surface of the metallic printable material (02) in the printing machine (01), wherein the surface of the metallic printable material (02) is pretreated in a plasma pretreatment device (13) in the printing machine (01) before being printed with the printing ink or with the lacquer, wherein the printing ink and/or the lacquer is/are each applied directly to a surface of the metal printable material (02), which surface is passivated with chromium, or chrome-plated, characterized in that the chromiferous surface of the metallic printable material (02) is irradiated with an ionized process gas in the plasma pretreatment device (13) under atmospheric pressure, wherein in the printing machine (01) a printing ink cured by irradiation with an ultraviolet radiation and/or a lacquer cured by irradiation with an ultraviolet radiation is/are respectively applied to the relevant surface of the metallic printable material (02).
2. The method according to claim 1, characterized in that oil-free compressed air from the atmosphere surrounding the printing machine (01) is used as the process gas pretreating the chromiferous surface of the metallic printable material (02) and/or in that nitrogen or an inert gas respectively from a carrier gas atmosphere is used as the process gas pretreating the chromiferous surface of the metallic printable material (02) .
3. The method according to claim 1 or 2, characterized in that a plate-shaped or web-shaped printable material (02) or a printable material (02) configured as a hollow body is used.
4. The method according to claim 1 or 2 or 3, characterized in that the chromiferous surface of the metallic printable material (02) is printed by at least one printing unit (03; 05; 07; 09) in the printing machine (01) arranged downstream of the plasma pretreatment device (13) in a letterpress printing method or a planographic printing method or in an offset printing process or in a plateless digital printing method.
5. The method according to claim 1 or 2 or 3 or 4, characterized in that the chromiferous surface of the metallic printable material (02) is continuously irradiated with an ionized process gas in the plasma pretreatment device (13).
6. A printing machine for printing a metallic printable material, having at least one printing unit (03; 05; 07; 09) for applying a printing ink and/or having at least one lacquering unit (11) for applying a lacquer respectively to a surface of the metallic printable material (02), wherein in the printing machine (01) in the transport direction (T) of the printable material (02) a plasma pretreatment device (13) is arranged upstream of the relevant printing unit (03; 05; 07; 09) for applying the printing ink and/or is arranged upstream of the relevant lacquering unit (11) for applying the lacquer to the surface of the metallic printable material (02), characterized in that the at least one printing unit (03; 05; 07; 09) applies the printing ink or the at least one lacquering unit (11) applies the lacquer respectively to a surface of the metallic printable material (02), which surface is passivated with chromium, or chrome-plated, wherein the at least one printing unit (03; 05; 07; 09) applies the printing ink and/or the at least one lacquering unit (11) applies the lacquer directly to the chromiferous surface of the printing material (02), wherein the plasma pretreatment device (13) irradiates the chromiferous surface of the metallic printable material (02) with an ionized process gas under atmospheric pressure, wherein the plasma pretreatment device (13) has a nozzle array (15), wherein the nozzle array (15) has a plurality of nozzles (16) both in the transport direction (T) of the printable material (02) as well as transversely thereto, wherein the ionized process gas streams from these nozzles (16) in a stream directed toward the chromiferous surface of the metallic printable material (02).
7. The printing machine according to claim 6, characterized in that the at least one printing unit (03; 05; 07; 09) applies a printing ink cured by irradiation with ultraviolet radiation to the surface of the metallic printable material (02) and/or that the at least one lacquering unit (11) applies a lacquer cured by irradiation with ultraviolet radiation to the surface of the metallic printable material (02) .
8. The printing machine according to claim 6 or 7, characterized in that the relevant printing unit (03; 05; 07; 09) for applying the printing ink to the chromiferous surface of the metallic printable material (02) or the relevant lacquering unit (11) for applying the lacquer to the chromiferous surface of the metallic printable material (02) is/are respectively printed in a letterset printing method or in a planographic printing method or in a screen printing method or in a plateless digital printing method.
9. The printing machine according to claim 6 or 7 or 8, characterized in that an intermediate dryer (04; 06; 08; 10) or an end dryer (12) is arranged in the transport direction (T) of the printable material (02) downstream of the relevant printing unit (03; 05; 07; 09) for applying the printing ink to the chromiferous surface of the metallic printable material (02) or is arranged downstream of the relevant lacquering unit (11) for applying the lacquer to the chromiferous surface of the metallic printable material (02).
10. The printing machine according to claim 6 or 7 or 8 or 9, characterized in that an intermediate dryer (04; 06; 08; 10) is respectively arranged between adjacently arranged printing units (03; 05; 07; 09) and a further intermediate dryer or an end dryer (12) is arranged downstream of the last printing unit (09) in the transport direction (T) of the printable material (02).
11. The printing machine according to claim 6 or 7 or 8 or 9 or 10, characterized in that a transport device is provided, with which transport device the printable material (02) is transported either in a gripper closure or in flat position on a suction belt by way of the printing machine (01).
12. The printing machine according to claim 6 or 7 or 8 or 9 or 10 or 11, characterized in that the respective nozzles (16) of the plasma pretreatment device (13) are arranged at a distance (a) in a region between 5 mm and 50 mm to the chromiferous surface of the metallic printable material (02) and/or that the respective nozzles (16) of the plasma pretreatment device (13) are respectively arranged perpendicular to the transport direction (T) of the printable material (02).
13. The printing machine according to claim 6 or 7 or 8 or 9 or 10 or 11 or 12, characterized in that the respective nozzles (16) of the plasma pretreatment device (13) are arranged such, that the printable material (02) to be printed by means of the printing machine (01) is treated inline by the plasma pretreatment device (13) with the process gas, wherein the nozzles (16) of the plasma pretreatment device (13) are selectively put to use by a control unit, wherein the treatment of the printable material (02) to be printed by the plasma pretreatment device (13) occurs only in selected regions.
14. The printing machine according to claim 6 or 7 or 8 or 9 or 10 or 11 or 12 or 13, characterized in that the respective nozzles (16) of the plasma pretreatment device (13) are arranged such, that the printable material (02) to be printed by means of the printing machine (01) is treated over the entire surface with the process gas by the plasma pretreatment device (13).
15. The printing machine according to claim 6 or 7 or 8 or 9 or 10 or 11 or 12 or 13 or 14, characterized in that the respective nozzles (16) of the plasma pretreatment device (13) are arranged continuously irradiating the chromiferous surface of the metallic printable material (02) with an ionized process gas.

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