EP3867076A1 - Method for printing on a surface of a nonabsorbent substrate with an ink to be applied by an inkjet printing device, and digital printing machine for carrying out said method - Google Patents

Abstract

The invention relates to a method for printing on a surface of a nonabsorbent substrate (01) with an ink to be applied by an inkjet printing device (02), wherein: an ink containing water as a solvent is used to print on the substrate (01), an ink having a water proportion of at least 70% being used; the substrate (01) to be printed on is supported by a workpiece support (04) and is moved relative to the inkjet printing device (02); during this relative movement, ink is applied by the inkjet printing device (02) to the surface of the substrate (01) to be printed on; the ink applied to the surface of the substrate (01) is heated to a temperature that lies above the temperature of the air surrounding the substrate (01) and below the boiling temperature of the of the solvent contained in the ink; a vapor layer consisting of the solvent contained in the ink is formed above a liquid phase of the ink; the vapor layer formed above the liquid phase of the ink is transported away by means of an air flow discharged from at least one blowing nozzle unit (06; 07); the air output by the blowing nozzle unit (06; 07) in question is heated and/or dehumidified beforehand. The invention further relates to a digital printing machine for carrying out said method.

Description

 description

Method for printing a surface of a non-absorbent substrate with an ink to be applied by an inkjet printing device and digital printing machine for carrying out this method

The invention relates to a method for printing on a surface of a

non-absorbent substrate with an ink jet printing device

ink to be applied according to claim 1 and a digital printing machine for performing this method.

WO 2018/168 675 A1 discloses a method for applying an oil-based ink to a substrate having a resin layer, the substrate being pretreated to improve the wetting properties before the oil-based ink is applied and after-treatment after the oil-based ink has been applied.

An image recording method is known from US 2017/0190188 A1, in which a recording substrate is subjected to a surface treatment in that an image recording surface of the recording substrate is exposed to light from a

Excimer emission is exposed using a xenon gas, which

Recording substrate is a non-absorbent or weak substrate

absorbent fiber materials, and wherein an ink composition is applied by an ink jet method to the image recording surface of the

Recording substrate is applied after the surface treatment.

An ink jet recording method is known from US 2018/0236787 A1, which comprises the application of a treatment liquid in which there is a content of a nitrogenous solvent, this content being greater than that in an ink composition, with little or no absorption capacity to the recording medium where surface imperfections are equal to or greater than 10 pm, the ink composition containing a nitrogen-containing solvent contains, by discharging the ink composition from an ink jet head onto the recording medium, wherein the treatment liquid previously on the

Recording medium has been applied.

From US 9 573 349 B1 a method for printing non-absorbent substrates with a water-based ink is known, in which ink drops are applied to the respective substrate, in which substrates are used, each having a surface tension of less than 45 mN / m, in which, prior to the application of the ink drops, the surface tension of the substrates to be printed is increased to a value of at least 45 mN / m, in which the ink drops are only then applied to the respective substrate having the increased surface tension.

US 2012/0026264 A1 shows a printed substrate

Exposure to heat, e.g. B. to dry by infrared radiation, for which

Drying temperature a range between 40 ° C and 100 ° C and a range between 0.2 s and 10 s is proposed for the exposure time.

CH 703 704 A1 discloses a printing device for printing flat structures in the form of tinplate sheets with at least one printing ink, the surface tension of these flat structures being less than the surface tension of the printing ink, comprising at least one activatable printing unit and a final drying system downstream of this at least one activating printing unit to the

Drying the printing ink applied to the fabric by the at least one activatable printing unit, with at least one irradiation device, each with at least one electromagnetic radiation source, for irradiating and increasing the upstream of the printing unit that can be activated first in the process sequence

Surface tension of the fabric is formed before it is fed to the first activatable printing unit, and the radiation source is an elongated UV gas discharge tube or an elongated infrared radiator. From DE 10 2012 017 538 A1, a method for treating the surface of objects with fluids is known, in which the fluid is applied by means of a computer-controlled first tool and then further processed with the second computer-controlled tool, the time delay between the application of the Fluids on the item and subsequent

Further treatment is adapted to the spreading behavior of the fluid.

The invention has for its object to provide a method for printing a surface of a non-absorbent substrate with an ink to be applied by an inkjet printing device and a digital printing machine for carrying out this method, with which non-absorbent substrates can be used despite the use of a

water-based ink can each be printed with a print image of high print quality, in particular avoiding the ink drops from spreading.

The object is achieved by a method with the features of

Claim 1 solved and by a digital printing press according to claim 36. The respective dependent claims relate to advantageous refinements and / or

Developments of the found solution.

The advantages that can be achieved with the invention are, in particular, that knowledge of the properties of the surface of the substrates to be printed that actually influence the wetting prior to printing is not necessary, but that the substrates to be printed are preferably immediately in front of them

Printing in a good condition, i.e. H. at least partially to very good, d. H.

complete wettability, while at the same time this measure avoids, or at least limits, possible negative effects on the printed substrates.

Another advantage is a very flat print with a low haptic ink build-up, ie a low relief formation, and a print with a high gloss level. B. in the packaging market frequently asked requirements simple way to be met. In addition, the formation of such printed substrates is made possible without disturbing abrasion in the forming machine. It is also a good prerequisite for overpainting and a low and therefore environmentally friendly ink application with water as an environmentally friendly solvent.

The proposed solution is illustrated using the single figure.

There is e.g. B. in packaging printing the need to print non-absorbent substrates in an industrial printing process with at least one water-based ink. These substrates are e.g. B to preferably consist of a solid, in particular flat substrates, for. B. to substrates each made of a metallic material, in particular to metal sheets, for. B. from a steel sheet or a tinplate or from an i. d. R. surface oxidized aluminum material. Alternatively, non-absorbent substrates made of, in particular, pre-lacquered wood, a plastic or a composite material can also be considered, provided that these substrates harmlessly heat during the printing process, e.g. B. survive dimensionally stable. The substrates are preferably in the form of plates or sheets. B. However, it may also be in the form of a web or in each case as a round body.

Metallic substrates in particular are i. d. R. with a primer, e.g. B. pre-coated with a white background and / or with a varnish. These substrates have z. B. an oiled or greased surface or treated with an anti-corrosion agent. The surface of the substrates to be printed is in particular hydrophobic. For printing on these substrates a z. B. pigment-based,

in particular soluble ink with a water content of at least 70%, in particular at least 80%. If it is provided that the substrate in question is to be further processed into packaging for food, an ink without photoinitiators is preferably used. To carry out the present invention, e.g. B. substrates with a non-polar surface and a polar ink for printing on this surface. The respective ink is in each case in the form of an ink jet printing device

Ink drops applied to the respective substrate, in particular by the

Use of at least one inkjet printhead which ejects the ink drops, the ink drops e.g. B. during a monodirectional movement (single pass method) or during a bidirectional movement (multi pass method) of the push button and / or the substrate in question are applied to the same. The ink drops z. B. in a screen printing process z. B. each in a point density of at least 360 dpi, for. B. 600 dpi or 1,200 dpi applied to the respective substrate. In order to generate a predetermined print image, the ink drops are usually applied in a grid with a plurality of positions in a precise position on the substrate in question. It can be provided that ink drops of variable size and / or that ink drops with

different hues and / or that ink drops in different

Brightness intensities are applied to the respective substrate. For a multicolored print image construction, color dots are preferably made from one

Basic color set, e.g. B. CMYK used.

In order to be able to successfully print on the substrates, the surface tension of the substrates in question must be at least as great as the surface tension of the ink used. This is the only way to at least partially wet the respective surface of the substrates in question with the intended ink. Otherwise they pull onto the non-absorbent surface of the substrates in question

applied ink drops together and wetting is not possible. If anything, if the surface tension of the substrates in question is inadequate, an at least unclear, in particular blurred or pale or color-incorrect and thus unusable printed image is produced. The surface tension of the substrates concerned and the surface tension of the ink used are usually temperature-dependent. Other environmental conditions such as B. the air humidity or certain surface properties of the substrates in question such as their roughness and / or their pretreatment and / or their degree of soiling affect the wettability of the respective surface of these substrates. The surface tension of solid substrates can e.g. B. can be determined with commercially available test inks. The surface tension of a water-based ink can e.g. B. with the help of the ring method from Lecomte De Noüy or with the help of the plate method from Wilhelmy or with the help of the ironing method from Lenard with a tensiometer or by the capillary effect or approximately also by a comparative measurement with test inks.

At room temperature, e.g. B. in surrounding air at a temperature of 20 ° C can be used for metallic substrates in solid form, d. H. especially for

Sheet metal z. B. assume the following values for their surface tension: untreated steel 29 mN / m

Aluminum (oxide) 33-35 mN / m

tinned steel approx. 35 mN / m

phosphated steel 43-46 mN / m

Oily or greased surfaces have a surface tension of around 30 mN / m.

In the following, it is assumed that substrates are used which each have a surface tension of less than z. B.

 50 mN / m, preferably less than 45 mN / m. Therefore i. d. R. each at the same room temperature of z. B. 20 ° C, the surface tension of the substrates provided for printing less than the surface tension of the water contained as a solvent in the ink and i. d. Usually also less than the surface tension of the ink used for printing itself.

At standard pressure (SATP), i.e. at 0.1 MPa corresponding to 1 bar and at a temperature of 20 ° C, water has a surface tension of 72.74 mN / m and at a temperature of 50 ° C a surface tension of 67.95 mN / m. To achieve good printing results, it is therefore provided that in the machine performing the printing process, e.g. B. in a printing press, in particular in a

at least one inkjet printhead that works without printing form

Digital printing machine, before applying the ink drops on the surface of the substrate to be printed, the surface tension of this surface z. B. is increased by at least 10%, preferably by more than 40% in each case to a value of at least 45 mN / m, in particular of at least 50 mN / m, preferably to a value of over 70 mN / m. Only after this increase in surface tension, i.e. H.

after the surface of the substrate to be printed has a sufficiently high surface tension, the ink drops are applied to the respective i. d. R. applied the increased surface tension substrate.

In order to improve the wettability of non-absorbent, in particular metallic surfaces provided for printing with a water-based ink, the

Surface tension of the substrates concerned z. B. by phosphating these substrates and / or by applying a suitable coating, eg. B. can be increased by applying a white background and / or a special coating.

Alternatively or additionally, the surface tension of the substrates in question can be increased by pretreating them with a corona process or with a plasma process or with a chemical process or by flame treatment or by UV radiation or by other methods of surface activation. When increasing the surface tension of the substrates to be printed, a value is sought and set which not only reaches a minimum value for the preferably complete wettability of the surface of the substrates in question, but i. d. R. significantly exceeds.

The surface tension of the substrates in question, which is higher than the minimum value for wettability, leads to a mostly strong spreading of the ink drops applied to their surface, ie. H. to an undesirable spread of this

Drops of ink on the surface of the substrates in question. Spreading the

Ink drop has a very quickly changing color property in the printed image Sequence and / or also leads to an unwanted flow of the ink z. B. into microwells of the substrate in question. Another effect is when using ink drops with different shades of bleeding these ink drops, z. B. by a merging of different color dots and thus leads to completely undesirable color effects in the printed image, not only in color, but also in the sharpness of the contour of printed structured surfaces, such as. B. in writing or on a picture edge.

Therefore, it is advantageous, preferably directly, i.e. H. stop or even largely prevent spreading of the ink drops within a single second, preferably within 0.5 seconds after the substrates have been printed, by in particular shock-like (over) drying. This is done in close proximity to the inkjet printing facility. In the case of a binder-based ink, this drying gels the at least one binder, which likewise causes the

Ink drops on the substrate in question is stopped or stopped. The shock-like (over) drying of the ink drops to stop or prevent them from spreading is also referred to as pinning. The pinning fixes ink drops applied to the substrate at their respective positions on the surface of the substrate to be printed.

1 illustrates the proposed method for printing on a surface of a non-absorbent substrate 01 with an ink to be applied by an inkjet printing device 02. In an industrial printing process, the substrate 01 is preferably printed with a digital printing machine having at least one inkjet printing device 02, and z. B. transported along a transport route 09. Arranged in each case in the direction of transport T of the substrate 01 indicated by directional arrows is generally a device 03 which pretreates the substrate 01 to be printed in the form of a device which increases the surface tension of the surface of the substrate 01 to be printed, this pretreating device 03 the surface tension of the to be printed Surface of the substrate 01 increased at least to that value that the surface tension of the Ink jet printing device 02 corresponds to ink to be applied to the surface of the substrate 01. This device 03 which increases the surface tension of the surface to be printed on the substrate 01 performs a pretreatment on the substrate 01 to be printed, for. B. with a corona process or with a plasma process or with a chemical process or by flame or by UV radiation.

The substrate 01 to be printed on a cooperating with the inkjet printing device 02 z. B. table-shaped workpiece carrier 04 z. B. laid flat. The inkjet printing device 02 and the workpiece carrier 04 are designed and arranged with respect to one another in such a way that the substrate 01 to be printed which is carried by the workpiece carrier 04 executes a relative movement to the inkjet printing device 02 or at least such a relative movement can be carried out, with ink on the surface during this relative movement from the inkjet printing device 02 of the substrate 01 to be printed is applied. The ink can be either during a monodirectional movement (single pass process) or during a bidirectional movement (multi pass process)

Ink jet printing device 02 or the workpiece carrier 04 are each applied to the surface of the substrate 01.

According to the workpiece carrier 04 is heated to a temperature above the surrounding air temperature and the substrate 01 carried by the workpiece carrier 04 is in turn z. B. by heat conduction of the workpiece carrier 04 within a very short time, for. B. heated in the range of less than 1 second, preferably even in the range of a few milliseconds, ie in less than 50 ms, in particular in less than 10 ms, with the result that the ink applied to the surface of the substrate 01 in particular by thermal conduction of the substrate 01 heated by workpiece carrier 04 in a practically equally short time, if necessary with an allowable deviation, ie a tolerance of at most 5 ° C., preferably at most 2 ° C., in particular on z. B. at least 90% of the elevated temperature of the heated workpiece carrier 01 is heated. The ink applied to the substrate 01 becomes as a result, a temperature which is significantly higher than the temperature of the air surrounding the substrate 01 is practically imprinted. The temperature of the ink applied to the substrate 01 is above the temperature of the air surrounding the substrate 01, but below a boiling temperature of the solvent contained in the ink, water being used as the solvent contained in the ink. The heating of workpiece carrier 04, substrate 01 and ink applied thereon is shown in FIG. B. indicated diagonally upward arrows. The workpiece carrier 04 is preferably heated by a heating device with which the temperature to be set for it is preferably regulated or at least controllable.

This heating of the ink applied to the substrate 01 results in a vapor layer above the liquid phase of this ink. This is because volatile constituents of the ink, which are primarily the solvent contained in the ink, in particular the water, have with increasing temperature the tendency to change from the liquid phase of the ink to a gaseous phase, which produces the vapor. Evaporation below the boiling point of the solvent contained in the ink, in particular water, is also known as evaporation. The evaporation rate and the steam pressure prevailing in the steam are on the one hand u. a. also depends on the material composition of the ink and its rheological properties. On the other hand, they are in the arrangement described above, but also by the surface tension of the ink and / or by the

Surface tension of the substrate 01 carrying the ink and its temperature can be influenced.

In the embodiment according to the invention it is provided that the vapor layer formed above the liquid phase of the ink by an air flow

to be removed and thereby removed. The air flow is through at least one blow nozzle unit 06; 07 provided, the respective blow nozzle unit 06; 07 expels the air flow towards the substrate 01 under machine environment conditions. In this case, the blow nozzle unit 06; 07 air usually heated and / or dehumidified beforehand. So z. B. in the inflow of the respective blow nozzle unit 06; 07, a heating device that is preferably regulated or at least controllable in the temperature to be set can be arranged. The respective can also

Blow nozzle unit 06; 07 with at least one z. B. line-shaped heating device, the respective heating devices each z. B. are designed as a radiation source in the IR or near IR range and / or are designed as LED emitters. The relative humidity of the respective blow nozzle unit 06; 07 expelled air flow is preferably less than 65%. The one of the respective

Blow nozzle unit 06; 07 provided air flow has a flow rate of z. B. more than 25 m / s, preferably more than 30 m / s, in particular more than 50 m / s or even more than 100 m / s. This air flow is at an angle of, for example, an angle starting from the support plane of the relevant substrate 01 resting on the workpiece carrier 04. B. 0 ° to 90 °, preferably in a range between 30 ° and 45 ° directed to the ink-bearing substrate 01, this air flow is preferably aligned with the transport direction T of the substrate 01 in question. A blow-out opening of the respective blow nozzle unit 06; 07 is arranged at a distance of 0.1 mm to 10 mm, preferably 2 mm, above the printed surface of the substrate 01 in question. The blow nozzle unit 06;

The air stream 07 provided removes the vapor layer formed above the liquid phase of the ink, but shifts the respective layer onto the substrate 01

not applied ink drops. With a monodirectional relative movement (single pass method) between substrate 01 and inkjet printing device 02, z. B. a single blow nozzle unit 07 in the transport direction T of the substrate 01 in question immediately after the inkjet printing device 02. With a bidirectional

Relative movement (multi pass process) between substrate 01 and

Inkjet printing device 02, it is advantageous to in each case immediately before and after the inkjet printing device 02 for intermediate drying of the substrate 01 in question and / or the ink applied to the surface of the substrate 01, a blow nozzle unit 06; Arrange 07 (Fig. 1). In a further embodiment, the blow nozzle units 06; 07 not only in front of and behind the inkjet printing device 02, but also between individual segments and / or between different colored ones Ink-delivering nozzles of this inkjet printing device 02 are arranged to enable an even more immediate intermediate drying of the individual ink orders.

As described above, it is advantageous that the ink applied to the surface of the substrate 01 is z. B. is dried by a heat input into the substrate 01 and / or in the applied ink in an intermediate drying different from the heat conduction of the workpiece carrier 04, this intermediate drying preferably by means of at least one blowing nozzle unit 06; 07 is running.

 Thereafter, the substrate 01 carrying the intermediate dried ink is exposed to an i. d. R.

conventionally designed (hot air and / or IR) end dryer 08 arranged spatially separated from the ink jet printing device 02 and z. B. passed through this final dryer 08, only this final drying effecting a complete physical drying of the ink and possibly its crosslinking. The intermediate drying of the ink application takes place during the printing process, that is to say practically at the same time as the printing process, immediately after or before the printing runs, in particular through the respective blowing nozzle unit 06; 07 and is with the

Printing process inextricably linked. The intermediate drying of the ink application is supported and / or intensified in the preferred embodiment by heating the substrate 01. The from the respective blow nozzle unit 06; 07, preferably jet-shaped air flow is applied to the surface of the substrate 01 and dries i. d. R. a whole area on this substrate 01. Die

Flow velocity of the blow nozzle unit 06; 07

The air flow provided determines an intensity of the drying of the ink applied to the surface of the substrate 01, this intensity being dependent on the distance from the preferably slot-shaped outlet opening of the respective blowing nozzle unit 06; 07 decreases. In a preferred embodiment, the respective

Blow nozzle unit 06; 07 several each in the transport direction T of the concerned

Substrate 01 lying one behind the other, preferably each transversely to the transport direction T of the substrate 01 in question, for. B. slot-shaped discharge openings. The intermediate drying of the relevant substrate 01 and / or the ink applied to the surface of the substrate 01 can be intensified by one or more heating devices arranged in particular in the area of the inkjet printing device 02, the respective heating device in each case e.g. B. as a radiation source in the IR or near IR range and / or as an LED emitter and z. B. in the direction of transport T of the relevant substrate 01 immediately before or after the inkjet printing device 02 inside and / or outside of the respective

Blow nozzle unit 06; 07 is arranged.

Reference list

01 substrate

 02 Inkjet printing device

03 pre-treatment facility

04 workpiece carrier

 05

 06 Blow nozzle unit

 07 Blow nozzle unit

 08 dryer

 09 Transport route

T direction of transport

Claims

Expectations 1. A method for printing a surface of a non-absorbent substrate (01) with an ink to be applied by an inkjet printing device (02), in which an ink containing water as a solvent is used for printing on the substrates (01), an ink with a water content of at least 70% is used, in which the substrate (01) to be printed by one  Workpiece carrier (04) carried and moved relative to the inkjet printing device (02), during which relative movement of the  Inkjet printing device (02) ink is applied to the surface of the substrate (01) to be printed, the ink applied to the surface of the substrate (01) being heated to a temperature which is above the temperature of the air surrounding the substrate (01) and below one  The boiling point of the solvent contained in the ink is located, a vapor layer consisting of the solvent contained in the ink being formed above a liquid phase of the ink, the vapor layer formed above the liquid phase of the ink being formed by one of at least one  Blowing nozzle unit (06; 07) ejected air stream is transported away, the air discharged from the respective blowing nozzle unit (06; 07) being previously heated and / or dehumidified. 2. The method according to claim 1, characterized in that of the respective  Blower nozzle unit (06; 07) the air flow is expelled with a relative humidity of less than 65%. 3. The method according to claim 1 or 2, characterized in that of the  the respective blow nozzle unit (06; 07) the air flow with a  Flow speed of more than 25 m / s is ejected. 4. The method according to claim 1 or 2 or 3, characterized in that the air stream ejected by the respective blowing nozzle unit (06; 07) in one of one Support level of the relevant one carried by the workpiece carrier (04)  Substrate (01) starting angle of 0 ° to 90 ° is directed onto the substrate carrying the ink (01). 5. The method according to claim 1 or 2 or 3 or 4, characterized in that the air stream ejected from the respective blow nozzle unit (06; 07) is rectified with the transport direction (T) of the substrate (01) in question. 6. The method according to claim 1 or 2 or 3 or 4 or 5, characterized in that the air stream ejected by the respective blow nozzle unit (06; 07) is ejected from a plurality of outlet openings located one behind the other in the transport direction (T) of the substrate (01) in question . 7. The method according to claim 1 or 2 or 3 or 4 or 5 or 6, characterized  characterized in that the relevant substrate (01) carried by the workpiece carrier (04) from at least one blow-out opening of the respective blowing nozzle unit (06; 07) arranged at a distance of 0.1 mm to 10 mm above the printed surface of the relevant substrate (01) ) is blown. 8. The method according to claim 1 or 2 or 3 or 4 or 5 or 6 or 7, characterized in that the of the respective blow nozzle unit (06; 07)  The air flow provided is expelled from at least one blow-out opening which is designed in the shape of a slot and transverse to the transport direction (T) of the substrate (01) in question. 9. The method according to claim 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8,  characterized in that the air flow provided by the respective blowing nozzle unit (06; 07) from between individual segments and / or between differently colored inks nozzles of the Ink jet printing device (02) arranged discharge openings is ejected. 10. The method according to claim 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 or 9, characterized in that a heating device arranged in the respective blowing nozzle unit (06; 07) is regulated in the temperature to be set. 1 1. The method according to claim 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 or 9 or 10, characterized in that the respective blow nozzle unit (06; 07) intermediate drying of the relevant substrate (01) and / or of the ink applied to the surface of the substrate (01) is carried out. 12. The method according to claim 11, characterized in that the intermediate drying of the relevant substrate (01) and / or the ink applied to the surface of the substrate (01) by one or more in the area of  Inkjet printing device (02) arranged heaters is reinforced. 13. The method according to claim 12, characterized in that in the transport direction (T) of the substrate in question (01) immediately after the  Ink heaters (02) arranged heaters can be used. 14. The method according to claim 12 or 13, characterized in that within  and / or arranged outside the respective blowing nozzle unit (06; 07)  Heaters are used. 15. The method according to claim 12 or 13 or 14, characterized in that in each case a radiation source radiating in the IR or near IR range is used as the respective heating device. 16. The method according to claim 12 or 13 or 14 or 15, characterized in that a respective linear heating device is formed as the respective heating device Radiation source is used. 17. The method according to claim 12 or 13 or 14 or 15 or 16, characterized  characterized in that an LED spotlight is used as the respective heating device. 18. The method according to claim 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 or 9 or 10 or 1 1 or 12 or 13 or 14 or 15 or 16 or 17, characterized in that the substrate carrying the ink ( 01) after the printing process is fed to an end dryer (08) which is spatially separated from the inkjet printing device (02), a hot air and / or IR end dryer (08) being used as the end dryer (08). 19. The method according to claim 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 or 9 or 10 or 11 or 12 or 13 or 14 or 15 or 16 or 17 or 18, characterized in that the ink during a monodirectional Relative movement between the substrate (01) and the inkjet printing device (02) (single pass method) is applied to the surface of the substrate (01) in question. 20. The method according to claim 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 or 9 or 10 or 11 or 12 or 13 or 14 or 15 or 16 or 17 or 18, characterized in that the ink during a bidirectional Relative movement between the substrate (01) and the inkjet printing device (02) (multi pass method) is applied to the surface of the substrate (01) in question. 21. The method according to claim 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 or 9 or 10 or 11 or 12 or 13 or 14 or 15 or 16 or 17 or 18 or 19 or 20, characterized in that the Workpiece carrier (04) on one  Temperature above the surrounding air temperature is heated. 22. The method according to claim 21, characterized in that the of Workpiece carrier (04) carried substrate (01) and on the surface of the Ink applied to the substrate (01) can be heated to the elevated temperature of the workpiece carrier (04) by thermal conduction of the workpiece carrier (04) with a permissible deviation. 23. The method according to claim 21 or 22, characterized in that the  Workpiece carrier (04) carried substrate (01) and the ink applied to the surface of the substrate (01) each by heat conduction of the  Workpiece carrier (04) to the elevated temperature of the workpiece carrier (04) with a permissible deviation of at most 5 ° C and / or to at least 90% of the elevated temperature of the workpiece carrier (04). 24. The method according to claim 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 or 9 or 10 or 11 or 12 or 13 or 14 or 15 or 16 or 17 or 18 or 19 or 20 or 21 or 22 or 23 , characterized in that the workpiece carrier (04) is heated by a heating device in which the temperature to be set for the workpiece carrier (04) is regulated. 25. The method according to claim 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 or 9 or 10 or 11 or 12 or 13 or 14 or 15 or 16 or 17 or 18 or 19 or 20 or 21 or 22 or 23 or 24, characterized in that the surface tension of the surface of the substrate (01) to be printed is increased at least up to that value which corresponds to the surface tension of the ink to be applied by the inkjet printing device (02) to the surface of the substrate (01). 26. The method according to claim 25, characterized in that the  Surface tension of the surface of the substrate (01) to be printed is increased in a device (03) pretreating the substrate (01) to be printed, this device (03) on the substrate (01) to be printed Pretreatment with a corona process or with a plasma process or with a chemical process or by flame treatment or by UV Radiation. 27. The method according to claim 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 or 9 or 10 or 1 1 or 12 or 13 or 14 or 15 or 16 or 17 or 18 or 19 or 20 or 21 or 22 or 23 or 24 or 25 or 26, characterized in that substrates (01) made from a metallic material or from wood or from a plastic or from a composite material are used. 28. The method according to claim 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 or 9 or 10 or 11 or 12 or 13 or 14 or 15 or 16 or 17 or 18 or 19 or 20 or 21 or 22 or 23 or 24 or 25 or 26 or 27, characterized in that in each case as plates or as sheets or in each case as one  Round-shaped substrates (01) can be used. 29. The method according to claim 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 or 9 or 10 or 11 or 12 or 13 or 14 or 15 or 16 or 17 or 18 or 19 or 20 or 21 or 22 or 23 or 24 or 25 or 26 or 27 or 28, characterized in that substrates (01) precoated with a primer and / or with a lacquer are used in each case. 30. The method according to claim 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 or 9 or 10 or 11 or 12 or 13 or 14 or 15 or 16 or 17 or 18 or 19 or 20 or 21 or 22 or 23 or 24 or 25 or 26 or 27 or 28 or 29, characterized in that substrates (01) with an oiled surface or with a greased surface or with a surface treated with an anti-corrosion agent are used. 31. The method according to claim 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 or 9 or 10 or 11 or 12 or 13 or 14 or 15 or 16 or 17 or 18 or 19 or 20 or 21 or 22 or 23 or 24 or 25 or 26 or 27 or 28 or 29 or 30, characterized in that the substrates (01) each have a table-shaped workpiece carriers (04) are carried. 32. The method according to claim 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 or 9 or 10 or 11 or 12 or 13 or 14 or 15 or 16 or 17 or 18 or 19 or 20 or 21 or 22 or 23 or 24 or 25 or 26 or 27 or 28 or 29 or 30 or 31, characterized in that a pigment-based ink is used for printing on the substrates (01). 33. The method according to claim 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 or 9 or 10 or 11 or 12 or 13 or 14 or 15 or 16 or 17 or 18 or 19 or 20 or 21 or 22 or 23 or 24 or 25 or 26 or 27 or 28 or 29 or 30 or 31 or 32, characterized in that an ink without photoinitiators is used for printing on the substrates (01). 34. The method according to claim 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 or 9 or 10 or 11 or 12 or 13 or 14 or 15 or 16 or 17 or 18 or 19 or 20 or 21 or 22 or 23 or 24 or 25 or 26 or 27 or 28 or 29 or 30 or 31 or 32 or 33, characterized in that as  Inkjet printing device (02) at least one inkjet printhead which ejects the ink in the form of ink drops, the  Ink drops are each applied to the respective substrate (01) in a dot printing process in a dot density of at least 360 dpi. 35. The method according to claim 34, characterized in that ink drops of variable size and / or ink drops with different colors and / or  Ink drops in different brightness intensities are each applied to the respective substrate (01). 36. Digital printing machine with at least one inkjet printing device (02) having at least one inkjet print head for carrying out the method according to one of claims 1 to 35.