IT201700005292A1 - Vorrichtung und Verfahren zum Bedrucken von unter thermischer Belastung sich verformenden Folien (German) Device and method for printing materials that deform under thermal stress - Google Patents

Description

Device and method for printing materials that deform under thermal stress

The present invention relates to a printing device and a process for printing on films that deform under thermal load, according to the general concept of claims 1 and 14.

According to the state of the art, a printer for printing on films is known, comprising: I) a reel with cylindrical casing, rotatable around an axis, to which is associated a printing module with four rows of nozzles arranged sequentially in the direction of rotation of the cylinder, and which are spaced from each other in front of the cylinder casing, so that the respective rows of nozzles can print different colors; II) means for maintaining the mantle temperature at a temperature between 20 and 90 degrees Celsius, wherein the printer is designed to print on the film as the film is moved through the cylinder casing.

Document US 6154232 A describes a printing device for printing on paper sheets, comprising: I) a printing drum with external surface of the drum suitable for receiving a sheet of paper, to which a printing module comprising two series of two rows of nozzles that are spaced apart from each other in front of the outer surface of the drum, where the width of a stripe of the ink printed on the sheet of paper is substantially equal to the sum of the strips printed by two rows of nozzles of the first series ; II) means for driving the print drum in a first direction of rotation, in which the printer is adapted to print on paper while the print drum is rotated in the direction of rotation. The image drum in (I) is configured as a vacuum drum to protect the sheet of paper against falling during rotation in the direction of rotation. For this purpose, the image drum is perforated with vacuum openings which extend between the inside of the image drum and the external surface of the drum and on which negative pressure can be applied.

From document DE 102009007565 A1 a guiding device is known for channeling the flexible flat material present in the form of a cloth or sheet of material, such as paper or plastic film, with at least one guiding surface on which the flat material can slide and where gas blowing channels bloom which act to blow air or other gases.

Document DE102013007300B4 further discloses a guiding device for channeling a web of material consisting of flexible flat material, having at least one web return unit.

Documents DE102009007565 A1 and DE102013007300B4 therefore only concern sheet guiding devices, for the return of flexible flat materials. The present invention, on the other hand, relates to a printing device for printing on a film.

Printing on a film is affected by several factors. These include, inter alia, the temperature, heat capacity, mass, geometric dimensions and material composition of the film used, as well as the energy that is added to or removed from the film, depending on their distribution on the film itself. . It should be noted that these factors also influence each other.

Another factor that influences the printing operation is the thermal expansion coefficient of a material of a film to be printed. A problem that causes rather low print quality when printing on films with relatively high coefficients of thermal expansion is that during processing the films expand and / or shrink, respectively, if they are exposed to thermal loads.

The inventors have observed that printing on a film with a prior art device, with ink droplets and with a selected droplet temperature that is lower than that of the film itself, increases distortion and therefore deterioration of the printout. . On the other hand it can be observed that the distortion of the printed matter increases the same, even in the case of greater energy supplied in the form of e.g. IR and / or NIR radiation during the printing operation, to evaporate and / or harden the ink drops at least partially in the meantime.

It can therefore be generally noted that an increase or decrease in temperature during the printing operation resulting from the influences described above, can cause a deterioration of the image, caused by a deformation of the film such that, during the gradual construction of the image , the ink droplets can no longer beat against their intended nominal positions. This means that according to the state of the art, in order to obtain a good-looking printout, one must try to avoid or at least minimize any variation in the temperature of the film during the printing operation.

If you remember that during the gradual construction of a printout, eg. during a Single Pass printing procedure with a Single Pass printing device, a 500 mm wide film is printed with a dot density of 600 dpi, i.e. with a distance of 42pm between two drops, and that during the operation initially undergoes a shrinkage of 2 millimeters and subsequently an extension of 3 millimeters, it becomes immediately understandable what negative effects the deformation will have on the appearance of the printed pattern.

In the context of this description the term "Single Pass Printing Device" refers to a printing device with a printing module for printing onto a film, in which the film is continuously moved into the operating mode, and the printing module encounters every film sector only once, so that the printing module does not operate according to the already known scanning procedure (i.e. with alternating line by line movement of a printing module), but instead with a stationary arrangement.

It is a fact that common plastics, eg. used for packaging films, however, almost always have a high coefficient of thermal expansion, so that they become very sensitive to temperature variations during processing, as shown in the following table 1:

Material Coefficient of Width of ΔΤ1 AS1 ΔΤ2 AS2 material thermal expansion SO [mm] [K] [mm] [K] [mm] a [° IC <1>]

paper -13 x 10 <-0> 500 10 0.065 40 0.26 aluminum (Al) -23 x 10 <-0> 500 10 0.115 40 0.46 polyethylene -80 x 10 * 500 10 0.4 40 1.6 polyamide -120 x 10 * 500 10 0,6 40 2,4 polypropylene -150 x 10 * 500 10 0,75 40 3,0 chloride di -175 x 10 <-0> 500 10 0,875 40 3,5 polyethylene (PE ) -200 x 10 * 500 10 1 40 4.0

Table 1

The thermal expansion AS1 and AS2 of typical plastics is a multiple of eg. to that of paper, with the same temperature variation. In the case of polyamide, polyvinyl chloride and polyethylene, it is about 6-15 times larger than paper.

Another factor that influences the printing operation and plays a decisive role in it is the thermal capacity of the film used. The heat capacity C of a substrate is by definition the ratio of the heat supplied to it (AQ) to the temperature increase (ΔΤ). The heat capacity of a substrate of homogeneous material can be established by calculating the product of the specific heat capacity C and its mass m.

Since the films by their very nature have relatively low thicknesses and typically within the range of 5 to 200 µm, preferably 10 to 100 µm, they are sensitive to the temperature variations which are created if energy is supplied or subtracted from the film.

Also, a combination of factors that affect printing on films that warp under thermal load occur if the film is a multi-material film, particularly if it is layered. For example, this is the case if, in the case of flexible films, an effective barrier is required in addition to a plastic layer carrying the print motif, e.g. against migrating components of UV ink. Such a barrier can be realized by providing e.g. a two or more layer film, comprising at least one metallic layer, e.g. a layer of aluminum.

A problem that can occur during the printing operation on multilayer films with different thermal expansion coefficients is a deterioration of the print quality due to the so-called bimetallic effect, so that, in the procedures according to the state of the art, the film arches under thermal load, so that the ink droplets can no longer reach their intended positions.

The multilayer film may even bend to contact the print nozzles which are normally only a few millimeters apart and face the surface of the film. This would involve eg. a contamination of the printing ink on the multilayer film.

There is therefore a need for a device and method for printing on films with a relatively high coefficient of thermal expansion, and which deform under thermal load, where the device and method, respectively, can at least partially and preferably completely suppress the effects. negatives of a thermal load.

It is therefore an object of the present invention to indicate a device and a process for printing on films with a relatively high coefficient of thermal expansion and which deform under thermal load, where the device and / or the process allow to maintain the stability of the shape of the films during a print operation, despite the thermal load.

This object is achieved with the device according to claim 1. Preferred embodiments of the device according to the invention are described in the subordinate claims.

According to claim 1, a printing device is indicated for printing on a film that deforms under thermal load, with at least one means for collecting at least one sector of a film with a collecting surface, to which at least one printing module is associated. printing for printing on the film using ink droplets, comprising at least one row of nozzles spaced from the collecting surface and arranged in front of it, where the collecting means comprises activatable sealing means.

According to the invention, the collection means comprises means for controlling the temperature of the collection surface.

The object is also achieved with the process for printing on a film that deforms under thermal load according to claim 14, comprising the following steps:

- provision of a printing device with at least one means for collecting at least one sector of the film with a collecting surface, to which at least one printing module is associated comprising at least one row of nozzles spaced from the collecting surface and arranged in front to it,

- application of the film sector having a temperature T1 on the collecting surface having a temperature T2, thus defining a temperature difference TU,

- printing with drops of ink on the sector of the film in contact with the collection surface.

According to the invention, one proceeds in such a way that, while a sector of the film in contact with the collection surface undergoes a temperature variation caused by an energy variation that is created if energy is supplied and / or subtracted in such a way as to cause a increase of the temperature difference TU between the film sector and the collection surface, at the same time through the collection surface sealing forces are applied to the film sector, where these sealing forces, opposing the deformation forces caused by the temperature variation in the film sector parallel to the collecting surface, they at least partially compensate for these deformation forces, preferably compensate them and particularly preferably overcompensate them.

The film, if subjected to thermal loads on a collecting surface, is then held on the collecting surface by sealing forces applied via the collecting surface, such that the sealing forces, opposing the deformation forces parallel to the direction of the surface and induced by the temperature, compensate at least partially these deformation forces, preferably compensate them and particularly preferably overcompensate them.

Unlike the case contemplated in US 6154232, the application of the sealing forces therefore not only and exclusively serves to fix a substrate against a possible fall of the film from a collection means, but according to the invention instead serves the purpose of avoiding the above described expansion and therefore the deformation of the film sector applied to the film collecting surface during the printing operation, so that in the meantime the stability of the shape of the film itself is maintained. Only with the solution revealed above can a deterioration in print quality be effectively avoided.

Deformations of the film before application on the above-described collection surface or following the detachment of the film from the same collection surface are on the other hand inevitable - on the contrary, they could even be desired or at least not interfere.

At the same time, the invention solves another problem that affects conventional processes for printing on films with relatively high thermal expansion coefficients, i.e. the film sector undergoes an uneven temperature distribution caused by the feeding and / or subtraction of energy, since even this negative effect is largely avoided with the solution according to the invention.

The cause of such an uneven temperature distribution can be based on several factors. These include, for example, the color of the ink and / or the application of the ink.

As is known, in the case of heat radiation, dark inks usually heat up much more than light inks. One of the causes is the interaction of the ink concerned with the near infrared (NIR), which however is not limited exclusively to the absorption of electromagnetic radiation, accompanied by the conversion of electromagnetic waves into heat, but also includes heat radiation. from the ink surface, i.e. the far infrared emission.

If, according to the state of the art, an image was printed in four-color process and with an uneven distribution of the colored inks, then exposing it to IR and / or NIR radiation, an uneven temperature distribution inevitably occurred with consequent non-homogeneous deformation. .

The present invention therefore also effectively solves the problem of the non-homogeneous distribution of the temperature in the film during the printing operation.

The invention is hereinafter described in detail and by way of example, with reference to the attached figures.

Fig. 1 shows a schematic side view in cross section of a particularly preferred embodiment of the printing device according to the invention.

Fig. 1 illustrates a "roll-to-roN" (R2R) type ink printing device for printing on a film 100 with a means for collecting 101 a sector of the film 100 with a collecting surface 103, in which the collecting means 101 is configured as a printing cylinder rotatable about an axis, with the collecting surface 103 configured as a cylindrical envelope.

Four printing modules 105a, 105b, 105c, 105d are associated with the cylindrical casing, each of which comprises at least one row of nozzles (not shown), spaced from the casing of the cylinder and arranged in front of it. In the direction of rotation of the printing cylinder (arrow) and downstream of the flow, the respective printing modules 105a, 105b, 105c, 105d are associated with sources of electromagnetic radiation 106a, 106b, 106c, 106d for at least partial hardening and / or at least partial evaporation of the ink drops applied to the film 100.

Advantageously, using one or more sources of electromagnetic radiation such as e.g. a source of IR and / or NIR radiation and / or a source of UV radiation, it is possible to prevent an unwanted wetting behavior of the ink drops printed on the film since they do not have enough time to spread or contract (depending on wetting type: no wetting, partial wetting, full wetting).

To pre-adjust the temperature of the film 100, the printing device comprises a pre-setting cylinder 115 with two relative pressure cylinders or NIPs 117 (non-contact printing), configured to press the movable film against the pre-setting cylinder 115 while the film 100 passes through it. pre-setting cylinder 115.

Thanks to this arrangement, the energy transfer from the cylinder to the film can be advantageously improved. The presetting cylinder can be adjusted in a temperature range of 20 to 100 degrees Celsius, preferably between 50 and 90 degrees Celsius.

As from the illustration in fig. 1, the film 100 can advance by means of an unwinding device (not shown), from a roll of film 127 through a device for adjusting the coating, configured as a dancer cylinder 133, and through a presetting cylinder 115, a deflection roller 119, a printing cylinder, a further deflection roller 121, a cooling cylinder 123 to cool the film 100, and through a second dancer cylinder 135, to be rewound by means of a winding device (not shown) in the form of a roll of 129 film.

The rollers and cylinders described above are mounted on a frame 131 of the printing device, with feet 134 fixed on the frame itself.

Three pressure cylinders or NIP cylinders 125 are also associated with the cooling cylinder 123, configured to press the movable film 100 against the cooling cylinder 123, while the film itself advances through the cooling cylinder 123.

The cylindrical envelope printing cylinder comprises means for adjusting the temperature of the collecting surface 103, as well as activatable sealing means, configured by suction channels which can be subjected to vacuum and which extend through a layer 104 towards the envelope of the cylinder, ending at the cylindrical casing in the form of suction openings (not shown). The layer 104 forms the collecting surface 103.

According to the invention, the sealing means that can be activated are configured so that, while the sector of the film 100 in contact with the collection surface 103 undergoes a temperature variation caused by a variation of energy which is created if energy is supplied and / or subtracted in such a way as to be able at the same time to apply, on the sector of the film 100 and through the collecting surface 103, such sealing forces that, opposing the deformation forces caused by the temporary temperature variation in the sector of the film 100 parallel to the collection 103, at least partially compensate for these deformation forces, preferably compensate them and particularly preferably overcompensate them.

The printing cylinder is supported on a hollow shaft 102, so that a tube (not shown) inserted into the hollow shaft, by means of a vacuum generator (not shown), can apply a certain negative pressure on the printing cylinder and thereby on the cylinder shell. By means of a temperature-regulated liquid in a second tube inserted in the hollow shaft 102, or by current means (not shown), the cylindrical casing is then adjustable to a desired temperature in the range between 20 and 100 degrees Celsius, preferably between 50 and 90 degrees Celsius.

A current medium can be a heating resistor capable of converting electrical energy into thermal energy.

The printing device further comprises an actuation means (not shown) capable of applying, directly or indirectly and unidirectionally or bidirectionally, a predetermined torque on the printing cylinder.

The printing device further comprises a control unit 132 for carrying out the printing method according to the invention.

A printing device has been revealed for printing on a film 100 which deforms under thermal load, with at least one means for collecting 101 at least one sector of a film 100 with a collecting surface 103, to which at least one module is associated printer 105a, 105b, 105c, 105d for printing on the film using ink drops, comprising at least one row of nozzles spaced from the collecting surface 103 and arranged in front of it, where the collecting means 103 comprises activatable sealing means .

According to the invention, the collection means 101 comprises means for controlling the temperature of the collection surface 103.

In a preferred embodiment of the invention, the sealing means that can be activated are configured so that, while the sector of the film 100 in contact with the collection surface 103 undergoes a temperature variation caused by an energy variation which is created if energy is fed and / or subtracted in such a way as to be able at the same time to apply, on the film sector 100 and through the collecting surface 103, such holding forces that, opposing the deformation forces caused by the temporary temperature variation in the film sector 100 parallel to the collecting surface 103, at least partially compensate for these deformation forces, preferably compensate them and particularly preferably overcompensate them.

In another preferred embodiment of the invention, the sealing means that can be activated are formed by suction channels in which a vacuum is applicable and which extend from the inside of the collection means 101 towards the collection surface 103, ending to the collection surface 103 in the form of suction openings.

In a particularly preferred embodiment of the invention, the means for the collection 101 comprises a layer 104 which comprises the suction channels, where the layer 104 itself constitutes the collection surface 103.

The layer 104 is preferably formed of nanoporous and / or microporous material.

The suction openings can be formed in the form of nanoporous and / or microporous openings.

The term "microopenings" used in the context of the invention refers to apertures with sizes from 1pm up to 200pm, preferably from 1pm up to 100pm. The term "nanooperture" instead refers to apertures with a size less than 1pm.

In a particularly preferred form of the invention, the (at least one) means for collecting a sector of the film 100 is configured in the form of a printing cylinder rotatable about an axis, and the collecting surface 103 is configured in the form of a cylindrical envelope, where the printing cylinder is arranged to turn the film 100 in a direction of rotation, thus defining a direction of advancement of the film 100.

In another particularly preferred embodiment of the invention, the printing cylinder is supported on a hollow shaft 102, so that a tube inserted into the hollow shaft, by means of a vacuum generator, can apply a certain negative pressure on the cylinder and thereby on the cylinder housing.

By means of a temperature-regulated liquid in a second tube inserted in the hollow shaft 102 or by current means, the cylindrical casing is adjustable to a desired temperature in the range of 20 to 100 degrees Celsius, preferably 50 to 90 degrees Celsius.

In a preferred embodiment, at least two, preferably at least four printing modules 105a, 105b, 105c, 105d are associated with the cylindrical envelope, spaced from each other in the direction of rotation.

In a further preferred embodiment, in the direction of rotation of the printing cylinder and downstream of the flow, at least one corresponding electromagnetic radiation source 106a, 106b, 106c, 106d is associated with the respective printing modules 105a, 105b, 105c, 105d for at least partial hardening and / or for at least partial evaporation of the ink drops applied to the film.

The (at least one) source of electromagnetic radiation 106a, 106b, 106c, 106d can be configured in the form of an IR and / or NIR radiation source.

The (at least one) source of IR and / or NIR radiation can be arranged between at least two printing modules 105a, 105b, 105c, 105d.

In a particularly preferred embodiment, the printing device comprises a presetting device for presetting the temperature of the film 100, preferably adjustable in a range between 20 and 100 degrees Celsius, particularly preferred between 50 and 90 degrees Celsius, where the presetting is arranged in the direction of advance of the film 100, in front of the printing cylinder and upstream of the flow. Preferably, the presetting device is configured in the form of a presetting cylinder 115.

In another particularly preferred embodiment, the printing device comprises a cooling device for cooling the film 100, preferably adjustable in a range between 20 and 40 degrees Celsius, where the cooling device is arranged in the direction of advance of the film. 100, in front of the print cylinder and downstream of the flow. Preferably, the cooling device is configured in the form of a cooling cylinder 123.

In another particularly preferred embodiment, the printing device comprises a final hardening and / or evaporation device for complete hardening and / or complete evaporation of the printed ink drops. Such a device may be a part of a subsequent processing device.

In a further particularly preferred embodiment of the invention, the printing device comprises a "roll-to-roll" (R2R) type printing device, particularly a "roll-to-roll" type inkjet printing device. to-roll ".

In a preferred embodiment, the printing device comprises an actuation means capable of applying, directly or indirectly and unidirectionally or bidirectionally, a predetermined torque on the printing cylinder. The drive means can be an electric drive motor.

The "roll-to-roll" printing device may comprise a device for winding and / or unwinding the film in the form of a continuous sheet of film onto / from a winding reel, which preferably comprises a drive means able to apply, directly or indirectly and unidirectionally or bidirectionally, a predetermined torque on the winding reel.

In a particularly preferred embodiment, the printing device comprises at least two printing cylinders operating sequentially, each provided with a cylindrical casing.

In a particularly preferred embodiment, the printing device and / or the "roll-to-roll" printing device, respectively, are configured in the form of a Single Pass printing device.

At this point it can be observed that the printing device can further comprise means for cleaning the film from soiling, and / or means for orienting the film or film sheet, and / or means for pretreating the film, such as ex. a corona treatment unit.

As a good rule, it is noted that for a better understanding of the configuration of the printing device, the device itself and / or its components have been represented not to scale and / or enlarged and / or reduced.

With reference to fig. 1, a particularly preferred embodiment of the method according to the invention for printing on films which deform under thermal load is described below.

In a first step, a printing device is provided with a means 101 for collecting at least one sector of a film 100, configured in the form of a printing cylinder. The printing cylinder comprises a collecting surface 103, configured in the form of a cylindrical casing, to which four printing modules 105a, 105b, 105c, 105d are associated, where each module comprises at least one row of nozzles (not shown), spaced apart one from the other and arranged in front of the collection surface 103.

In the exemplary method, the printing cylinder was arranged in the form of a printing cylinder with a cylindrical housing having a diameter of 1.4 meters.

In a second step, by means of a presetting cylinder 115 the film 100 is preset to a temperature of 88 degrees Celsius; and in a third step it is applied to the casing of the cylinder at a temperature T1 of 88 degrees Celsius, and the casing itself is pre-adjusted to a temperature T2 of 90 degrees Celsius. Temperature T1 and temperature T2 define a temperature difference TU of 2 degrees Celsius.

In a fourth step, it is printed on the film sector 100 which is in contact with the cylindrical envelope, by expelling water-based ink drops with a temperature of 40 degrees Celsius from the nozzles of the nozzle rows of the four modules. print 105a, 105b, 105c, 105d.

In a fifth step, the ink drops are subsequently evaporated at least partially, by means of the sources of electromagnetic radiation, arranged in front of the printing modules 105a, 105b, 105c, 105d and downstream of the flow, which act as sources of IR radiation and / or NIR 106a, 106b, 106c, 106d.

While the sector of the film 100 which is in contact with the cylindrical envelope undergoes a change in temperature, caused by a change in energy created when, by printing with ink drops with a lower temperature than the sector of the film 100 in contact with the cylindrical envelope, energy is subtracted and at the same time fed, with IR and / or NIR radiation, by at least partially drying the water-based ink drops printed on the sector of the film 100 in contact with the cylindrical envelope, so that an increase in the temperature difference TU is effected between the sector of the film 100 and the collection surface 103, at the same time, through the collection surface 103, sealing forces are applied to the sector of the film 100, where such sealing forces, opposing the deformation forces caused by the temperature variation in the sector of the film 100 parallel to the surface the picking elements 103, at least partially compensate for these deformation forces, preferably compensate them and particularly preferably overcompensate them.

A method for printing on a film 100 which deforms under thermal load has been revealed, comprising the following steps:

a) provision of a printing device with at least one means 101 for collecting at least one sector of the film 100 with a collecting surface 103, to which at least one printing module 105a, 105b, 105c, 105d is associated, comprising at least one row of nozzles spaced from the collection surface 103 and arranged in front of it,

b) applying the sector of the film 100 having a temperature T1 on the collecting surface 103, having a temperature T2, thus defining a temperature difference TU,

c) printing with drops of ink on the sector of the film 100 in contact with the collecting surface 103.

According to the invention, while the sector of the film 100 in contact with the collection surface 103 undergoes a temperature variation, caused by a variation of energy which is created if energy is supplied and / or subtracted in such a way as to cause an increase in the temperature difference TU between the sector of the film 100 and the collection surface 103, through the collection surface 103 at the same time sealing forces are applied to the sector of the film 100, where these sealing forces, opposing the deformation forces caused by the variation of temperature in the sector of the film 100 parallel to the collecting surface 103, at least partially compensate for these deformation forces, preferably compensate them and particularly preferably overcompensate them.

A preferred embodiment of the method according to the invention is characterized in that at the same time, with the sector of the film 100 in contact with the collecting surface 103, under the influence of an additional temperature variation by exchange of energy between the 103 and the sector of the film 100 a reduction of a current temperature difference TU is supported, and preferably carried out, in such a way that an at least partial approximation of an actual temperature of the sector of the film 100 to the temperature T2.

In a preferred embodiment of the method, the sealing forces are applied in the form of vacuum sealing forces, by means of sealing means equipped with suction channels, on which a vacuum is applicable and which extend from the inside of the means to the collection towards the collection surface 103, ending on the collection surface 103 in the form of suction openings.

In another preferred embodiment of the method, the collection means is provided in the form of a collection means comprising a layer 104 which includes suction channels, where the layer 104 itself constitutes the collection surface 103 and where the layer is preferably formed of nanoporous and / or microporous material.

The collecting surface 103 can be provided in the form of a collecting surface 103 with sufficiently small suction nozzles, so that the sectors of the film 100 directly affected by the suction nozzles can maintain a stable shape relative to the effect of the sealing forces vacuum, i.e. that the sectors of the film 100 affected by the vacuum sealing forces (suction forces) are not plastically deformed.

In a particularly preferred embodiment of the invention, the collection surface 103 is provided in the form of a collection surface 103 with suction outlets configured as nano-openings and / or micro-openings.

Before application on the collection surface 103, the sector of the film 100 can be pre-adjusted so as to have, at the time of application on the collection surface 103, a temperature T1, defining, relative to the temperature T2, a temperature difference TU in a range between at least 0 and 10 degrees Celsius, preferably between 0 and 5 degrees Celsius.

In some embodiments of the method according to the invention, especially if ink drops with a lower temperature than that of the film 100 are printed on the film 100, it may be advantageous if the film 100, at the time of application on the surface of collection 103 and compared to the latter, it has a slightly lower temperature. During the printing operation, due to the small temperature difference, higher deformation forces can be prevented in advance.

Prior to application on the collection surface 103, the sector of the film 100 can therefore be pre-adjusted so as to have, at the time of application on the collection surface 103, a temperature T1 which, relative to the temperature T2, is set to a lower value. in a range between at least 2 and 10 degrees Celsius, preferably between 2 and 5 degrees Celsius.

In a preferred configuration, the sealing forces can be determined as a function of a predetermined maximum temperature variation, and the latter can be considered for adjusting the sealing forces in such a way that, by opposing the deformation forces caused, these forces of deformation are compensated at least partially, preferably compensated and particularly preferably overcompensated.

In a particularly preferred configuration, the printing with ink drops takes place at a lower temperature than that of the sector of the film 100 which is in contact with the collection surface 103, with consequent subtraction of energy which causes the temperature variation in the sector of the film 100. In this case, the cause of the energy loss is therefore the ink itself with its temperature lower than that of the film.

In a preferred embodiment, according to step d) of the process and due to the IR and / or NIR radiation, at least partial evaporation and / or hardening of the ink drops printed on the sector of the film 100 which is in contact with the collecting surface 103, so that the temperature variation is caused by the energy supply.

In another preferred embodiment, according to step e) of the method and instead of step d) of the method and / or in addition to this step, air with a temperature between 15 and 180 ° is blown by means of a blowing means C on the ink drops printed on the sector of the film 100 which is in contact with the collecting surface 103, so that the temperature variation is similarly caused by the subtraction or supply of energy. This procedure is advantageous because, among other things, a layer of air that covers the ink can be eliminated more quickly.

Steps d) and e) can be performed simultaneously or in two separate phases.

Instead of or in addition to step d), the hardening of the ink drops can take place by UV radiation in a step f).

In a preferred embodiment of the method according to the invention, before step b) the collecting surface 103 is regulated by means for regulating the temperature on a certain temperature T2 in a range between 50 and 100 degrees Celsius, preferably between 60 and 100 degrees Celsius, especially preferred between 80 and 100 degrees Celsius; and at least during the subsequent steps b) and c) this temperature is kept at least partially constant and preferably constant.

In a particularly preferred embodiment, the ink used is a water-based ink.

Unlike other acrylic-based inks which consist largely of one or more monomers, water-based inks enable the production of thinner, hardened ink films on a substrate. Advantageously, this also makes it possible to dispense with expensive acrylate monomers as starting material.

The temperature of the ink droplets can reach a lower temperature, compared to the current temperature of the film sector 100, in a range between 20 and 60 degrees Celsius, preferably between 30 and 50 degrees Celsius.

An aqueous-based hybrid ink can be used as the water-based ink, comprising the components (a) water, (b) oligomer and / or UV-curing polymer with ethylenically unsaturated functional groups, (c) a wetting agent and (d) a radical producing photoinitiator.

The term "oligomer" used in the context of the present disclosure refers to a molecule with a molecular mass in the range of 1,000 (inclusive) to 10,000 (inclusive). The term "polymer" used in the context of the present description, on the other hand, refers to a molecule with a molecular mass greater than 10,000.

A preferred hybrid ink comprises the following components:

(a) 20 to 70%, preferably 40 to 70% component (a),

(b) from 5 to 50%, preferably from 05 to 25% component (b),

(c) from 02 to 40%, preferably from 05 to 30% component (c),

(d) from 0.1 to 05%, preferably from 0.5 to 3.0% component (d)

In the context of the present description the percent symbol "%" refers to percentages by weight.

The application of the film 100 on the collecting surface 103 can take place under a first predetermined tensile stress in a first direction and a second tensile stress, in the vertical direction with respect to the first direction, where the first and second tensile stresses are zero. or other than zero.

In a particularly preferred embodiment, the application of the film on the collecting surface 103 takes place under a first tensile stress of <1500N, in particular <700N, and a second tensile stress of preferably <300N, in particular <200N.

The film 100 can be provided in the form of an elastically deformable film 100.

The film 100 can be provided in the form of a film 100 comprising a thermoplastically deformable plastic material.

The film 100 can be provided in the form of a multilayer film, comprising at least one thermoplastically deformable plastic layer and optionally at least one metallic layer and / or at least one paper layer.

In a preferred embodiment, for the film 100 a film 100 is selected with at least one layer having a coefficient of thermal expansion a of at least 40 <*> 10 <'6 *> ° K <'> \ preferably at least 70 <* > 10 <'6 *> ° K <' 1>.

Typically, the film 100 is provided with a thickness between 5 and 200pm, preferably between 10 and 100pm.

In a particularly preferred embodiment, the process comprises the following steps:

- providing a printing cylinder rotatable about an axis 102, as a means for collecting 101 with cylindrical envelope as a collecting surface 103,

- drive of the printing cylinder in one direction of rotation, where the rotation occurs with a synchronous dragging of the film 100 in the direction of rotation of the printing cylinder,

- print on film 100 with ink drops.

The printing device can be provided in the form of a "roll-to-roH" printing device, in particular a "roll-to-roll" inkjet printing device, so that the film 100 is processed in the form of a continuous sheet of film from a roll and which is continuously applied to the cylindrical envelope.

The temperature presetting can take place by means of a presetting device, preferably configured as a presetting cylinder (115) through which the film 100 is guided.

Typically, the film 100 is provided in the form of a film 100 with a width ranging from at least 100mm to 1000mm.

Claims (35)

Claims: 1. Printing device for printing on a film (100) which deforms under thermal load, with at least one means for collecting (101) at least one sector of a film (100) with a collecting surface (103) to which at least one printing module (105a, 105b, 105c, 105d) is associated for printing on the film using ink drops, comprising at least one row of nozzles spaced from the collecting surface (103) and arranged in front of it, where the medium for the collection (103) comprises sealing means that can be activated, characterized in that the collection means (101) comprises means for regulating the temperature of the collection surface (103). 2. Printing device according to claim 1, characterized in that the sealing means that can be activated are configured so that, while the sector of the film (100) in contact with the collecting surface (103) undergoes a temperature variation caused by a variation of energy that is created if energy is supplied and / or subtracted in such a way as to be able to simultaneously apply, on the sector of the film (100) and through the collecting surface (103), such holding forces that, opposing the forces of deformation caused by the temporary temperature variation in the sector of the film (100) parallel to the collecting surface (103), at least partially compensate for these deformation forces, preferably compensate them and particularly preferably overcompensate them. 3. Printing device according to claim 1 or 2, characterized in that the sealing means that can be activated are formed by suction channels in which a vacuum is applicable and which extend from the inside of the collection means towards the collection surface (103), ending at the collection surface (103) in the form of suction openings, through which a negative pressure can be applied to the film (100) through a vacuum generator. Printing device according to claim 3, characterized in that the collecting means (101) comprises a layer (104) which includes the suction channels, where the layer (104) forms the collecting surface (103) and where the layer is preferably made of nanoporous and / or microporous material. 5. Printing device according to claim 3 or 4, characterized in that the suction openings are constituted in the form of nano-openings and / or micro-openings. Printing device according to at least one of the preceding claims, characterized in that the (at least one) collecting medium (101) of the film sector (100) is configured in the form of a printing cylinder rotatable around a axis, and the collecting surface (103) is configured in the form of a cylindrical envelope, where the printing cylinder is arranged to turn the film (100) in a direction of rotation, thus defining a direction of advance of the film (100) . Printing device according to claim 6, characterized in that the printing cylinder is supported on a hollow shaft (102) so that a tube inserted into the hollow shaft, by means of vacuum means, can apply a certain negative pressure on the printing cylinder and thereby on the cylinder housing. 8. Printing device according to claim 6 or 7, characterized in that, by means of a liquid at a controlled temperature in a second tube inserted in the hollow shaft (102) or by means of current means, at least the cylindrical casing is adjustable on a desired temperature in the range between 20 and 100 degrees Celsius, preferably between 50 and 100 degrees Celsius, particularly preferably between 60 and 100 degrees Celsius. 9. Printing device according to at least one of claims 6 to 8, characterized in that at least two, preferably at least four, printing modules (105a, 105b, 105c, 105d), are positioned spaced apart from each other in the direction of rotation. Printing device according to at least one of claims 6 to 9, characterized in that in the direction of rotation of the printing cylinder and downstream of the flow, to the printing module or to the printing modules (105a, 105b, 105c, 105d) at least one corresponding electromagnetic radiation source (106a, 106b, 106c, 106d) is associated for at least partial hardening and / or for at least partial evaporation of the ink drops applied on the film (100), where the radiation source electromagnetic is preferably configured in the form of an IR and / or NIR radiation source. Printing device according to at least one of claims 6 to 10, characterized in that the printing device comprises a presetting device for presetting the temperature of the film sector (100), preferably configured as a presetting cylinder (115), preferably adjustable in a range between 20 and 100 degrees Celsius, particularly preferred between 50 and 90 degrees Celsius, where the presetting device is arranged in the direction of advance of the film (100) in front of the printing cylinder and upstream of the flow. 12. Printing device according to at least one of the preceding claims, characterized in that the printing device is a "roll-to-roll" type printing device, particularly a "roll-to-roll" type inkjet printing device. roll ". 13. Printing device according to at least one of claims 6 to 12, characterized in that the printing device comprises a control unit for carrying out a method according to at least one of claims 14-36. 14. Process for printing on a film (100) which deforms under thermal load, comprising the following steps: a) provision of a printing device with at least one means for collecting (101) at least one sector of the film (100) with a collecting surface (103), to which a printing module (105a, 105b, 105c is associated) , 105d), comprising at least one row of nozzles spaced from the collection surface (103) and arranged in front of it, b) application of the sector of the film (100) having a temperature T1 on the collecting surface (103), having a temperature T2, thus defining a temperature difference TU, c) printing with ink drops on the film sector (100) in contact with the collection surface (103), where, while the film sector (100) in contact with the collection surface (103) undergoes a variation of temperature caused by a change in energy that is created if energy is supplied and / or subtracted in such a way that an increase in the temperature difference TU between the film sector (100) and the collecting surface (103) is caused, at the same time on the film sector (100) and through the collection surface (103), sealing forces are applied such that, opposing the deformation forces caused by the temperature variation in the film sector (100) parallel to the collection surface ( 103), at least partially compensate for these deformation forces, preferably compensate them, and particularly preferably overcompensate them. Method according to claim 14, characterized in that simultaneously, with the film sector (100) in contact with the collecting surface (103), under the influence of an additional temperature change by energy exchange between the collecting surface (103) and the film sector (100) a reduction of a current temperature difference TU is supported, and preferably carried out, so that an at least partial approximation of an actual temperature of the film sector is supported, and preferably carried out. film (100) at temperature T2. Method according to one of claims 14 or 15, characterized in that the sealing forces are applied in the form of vacuum sealing forces, by means of activated sealing means, consisting of suction channels, on which a vacuum is applicable and which they extend from the inside of the collecting means (101) towards the collecting surface (103) and ending at the collecting surface (103) in the form of suction openings. Method according to at least one of the preceding claims 14 to 16, characterized in that, prior to application on the collecting surface (103), the film sector (100) is pre-adjusted so as to have, at the time of application on the collection surface (103), a temperature T1 defining, relative to the temperature T2, a temperature difference TU in a range between 0 and 10 degrees Celsius, preferably between 0 and 5 degrees Celsius. 18. Process according to at least one of the preceding claims 14 to 17, characterized in that, prior to application on the collecting surface (103), the film sector (100) is pre-adjusted so as to have, at the time of application on the collecting surface (103), a temperature T1 which, relative to the temperature T2, is regulated in a small range between at least 2 and 10 degrees Celsius, preferably between 2 and 5 degrees Celsius. 19. Process according to at least one of the preceding claims 14 to 18, characterized in that the sealing forces can be determined as a function of a predetermined variation in the maximum temperature that can be produced, and the latter can be considered for the adjustment of the sealing forces in such a way that, by opposing the deformation forces caused, these deformation forces are compensated at least partially, preferably compensated and particularly preferably overcompensated. Method according to at least one of the preceding claims 14 to 19, characterized in that the printing with ink drops takes place at a lower temperature than that of the film sector (100) which is in contact with the collecting surface (103) with consequent subtraction of energy which causes the temperature variation in the film sector (100). 21. Process according to at least one of the preceding claims 14 to 20, characterized in that the process comprises a further step: d) evaporation and / or at least partial hardening of the ink drops printed on the sector of the film (100) which is in contact with the collecting surface due to IR and / or NIR and / or UV radiation, so that the temperature variation is caused by the power supply. 22. Process according to claim 21, characterized in that in one step e), instead of step d) of the process or in support of it, by means of an air blowing means air with a temperature between 15 and 180 ° C is blown onto the ink drops printed on the sector of the film 100 which is at contact with the collecting surface 103, so that the temperature variation is correspondingly caused by the subtraction or supply of energy. 23. Method according to at least one of the preceding claims 14 to 22, characterized in that, before step b), the collecting surface (103) is adjusted by means for regulating the temperature to a certain temperature T2 in a range between 50 and 100 Celsius, preferably between 60 and 100 degrees Celsius, particularly preferred between 80 and 100 degrees Celsius; and at least during the subsequent steps b) and c) this temperature is kept at least partially constant and preferably constant. Method according to at least one of the preceding claims 14 to 23, characterized in that the temperature of the ink drops, compared to the current temperature of the film sector (100), reaches a lower temperature in a range between 20 and 60 degrees Celsius, preferably between 30 and 50 degrees Celsius. Method according to at least one of the preceding claims 14 to 24, characterized in that an aqueous-based ink is used for the ink. 26. Process according to at least one of the preceding claims 25 [sic], characterized in that, as aqueous-based ink, an aqueous-based hybrid ink is used, comprising the components (a) water, (b) oligomer and / or UV polymer -hardener with ethylenically unsaturated functional groups, (c) a wetting agent and (d) a radical producing photoinitiator. Method according to at least one of the preceding claims 14 to 26, characterized in that the application of the film (100) on the collecting surface (103) takes place under a first predetermined tensile tension in a first direction and a second tension tension traction, in the vertical direction with respect to the first direction, where the first and second traction stresses are zero or different from zero, where the application of the film (100) on the collecting surface (103) preferably takes place under the first traction tension of <1500N, in particular <700N, and under the second tensile stress of <300N, in particular <200N. Method according to at least one of the preceding claims 14 to 27, characterized in that the film (100) is provided in the form of an elastically deformable film (100). 29. Process according to at least one of the preceding claims 14 to 28, characterized in that the film (100) is provided in the form of a film (100) comprising a thermoplastically deformable plastic material. 30. Process according to at least one of the preceding claims 14 to 29, characterized in that the film (100) is provided in the form of a multilayer film, comprising at least one thermoplastically deformable plastic layer and optionally at least one metallic and / or at least one layer of paper. Method according to at least one of the preceding claims 14 to 30, characterized in that a film (100) with at least one layer having a thermal expansion coefficient a of at least 40 <*> 10 <is selected for the film (100) '6 *> ° K <'> \ preferably at least 70 <*> 10 <'6 *> ° K <' 1>. 32. Process according to at least one of the preceding claims 14 to 31, characterized in that the film (100) is supplied with a thickness between 5 and 200pm, preferably between 10 and 100pm. 33. Process according to at least one of the preceding claims 14 to 32, characterized in that the process comprises the following steps: - provision of an axis-rotatable printing cylinder (102) as a collecting medium (101) with cylindrical envelope as a collecting surface (103), - drive of the printing cylinder in one direction of rotation, where the rotation occurs with a synchronous dragging of the film (100) in the direction of rotation of the printing cylinder, - printing on the film (100) with ink drops. Method according to claim 33, characterized in that the printing device can be provided in the form of a "roll-to-roll" printing device, in particular a "roll-to-roll" inkjet printing device ", so that the film (100) is processed in the form of a continuous web of film from a roll and is continuously applied to the cylindrical envelope. Method according to at least one of the preceding claims 14 to 34, characterized in that the temperature presetting takes place by means of a presetting device, preferably configured as a presetting cylinder (115) through which the film (100) is guided.