EP2064062B1 - Device for printing by transfer onto a cylindrical print support - Google Patents

Description

The present invention relates to the general technical field of printing information, variable or identical from one printing to the next, on a cylindrical printing medium, preferably metal. The print medium may for example be an object to decorate.

The present invention applies in particular to the field of prints using ink jet printing.

More particularly, the invention relates to the field of transfer printing on a cylindrical and metallic printing medium.

GENERAL PRESENTATION OF THE PRIOR ART

The printing or decoration of cylindrical and metal objects is generally based to date on various conventional printing processes such as flexography, offset (double offset printing) or pad printing. These processes based on the transfer of ink previously deposited on a blanket, are intended for the printing of constant patterns reproduced in large numbers (several hundreds of thousands of copies).

The principle of these methods is to use a plate engraved with the pattern to be reproduced. At first, this plate is coated with ink. Then, in a second step, the ink-coated plate is applied to the blanket which collects the ink on its surface. In a third step, the ink collected on the surface of the blanket is transferred to the cylindrical printing medium by means of a calibrated pressure of the blanket on the printing medium.

Although these technologies are well adapted to the printing of constant patterns at high volume, they do not allow the printing of variable patterns from one impression to another, typically based on digital or digital data.

The same problem arises for an impression using a screen printing technique.

Indeed, with each change of pattern, these technologies require changing the engraved plate with the pattern to reproduce or screen printing, and clean the blanket.

The document WO 03/103966 describes a device for printing a polychrome image composed of at least two partial images. The device includes an object carrier for conveying objects to be printed using a blanket. The device also includes inking mechanisms and cylindrical plates for offset printing of the blanket.

The document WO 2004/113082 describes a device comprising means capable of depositing an intermediate transfer body on a blanket and digital printing means capable of projecting ink on the intermediate body, the image thus formed being then transferred onto a planar object of type continued.

The document US 2005/0045053 discloses a device for printing a cylindrical support comprising digital ink jet printing means.

The general object of the invention is to provide a transfer printing method to overcome the disadvantages of existing printing processes.

In particular, an object of the present invention is to provide a printing method and an associated device for printing cylindrical printing media, easier to implement than existing methods, and to obtain results.

PRESENTATION OF THE INVENTION

For this purpose, according to the present invention, a printing device according to claim 1 is provided.

In the context of the present invention, the term "surface of the printing medium" refers to the surface to be printed of the printing medium.

The surface to be printed is located on the side face of the cylindrical printing medium. It can correspond either to one (or more) portion (s) of this side face, or to the entire side face.

In all cases, the surface to be printed is continuous, that is, the printed image covers the entire circumference of the cylindrical printing medium.

• au moins un blanchet présentant une surface supérieure à celle du support d'impression, et
• des moyens numériques d'impression par projection d'encre sur le blanchet sur une surface égale à celle du support d'impression, permet :

• d'imprimer des supports d'impression de dimensions différentes avec des motifs de forme et de dimensions différentes sans devoir changer de blanchet.
• d'augmenter la qualité de l'impression, d'une part en fermant correctement l'image imprimée sur le support d'impression cylindrique, et d'autre part en évitant les recouvrements.

The fact that the device comprises in combination:

• at least one blanket having a surface area greater than that of the printing medium, and
• digital inkjet printing means on the blanket on a surface equal to that of the printing medium, allows:

• to print print media of different sizes with patterns of different shapes and sizes without having to change the blanket.
• to increase the quality of the printing, on the one hand by closing correctly the image printed on the cylindrical printing support, and on the other hand by avoiding the recoveries.

In a variant, the blanket is a continuous single band in motion.

In another variant, the (or each) blanket is a sheet.

In these two variants, the blanket may be integral with a carousel or a roller, for example a rubberized roller. The blanket may also be disposed around at least one motorized flat pulley.

Optionally, the device also comprises means capable of measuring the amplitude of the printing medium.

The ink jet printing means may comprise one or a plurality of printing heads arranged such that the distance between a print head and the blanket is constant. This makes it possible to improve the quality of the printing, the projection distance of the drops on the blanket being constant.

In one embodiment, the device also comprises means for fixing the ink by applying a treatment on the ink.

In this case, the ink fixing means are able to fix the ink partially on the blanket. This makes it possible to improve the transfer of the image of the blanket onto the printing medium, and thus to improve the quality of the printing. In one embodiment, the fixing means may also allow the fixing of the ink on the print medium.

• ∘ soit par le blanchet sous l'action des forces de friction entre le support d'impression et blanchet,
• ∘ soit par un élément des moyens, ledit élément permettant la mise en rotation du support lorsque le support et le blanchet sont en contact.

When the print medium and the blanket are in contact, the print medium can be rotated:

• ∘ either by the blanket under the action of the friction forces between the printing medium and the blanket,
• Or by an element of the means, said element allowing the rotation of the support when the support and the blanket are in contact.

Advantageously, the movement of the blanket may be a rotational movement.

According to a nonlimiting variant developed by IMPIKA, the device may comprise means for applying a liquid receiving layer to the blanket. The ink application means may allow the deposition of the liquid receiving layer before or after the application of the image by the digital printing means. The receiving layer and the ink may be of different natures to allow a targeted attachment of the receiving layer or inks by the fixing means.

The invention also relates to a printing method according to claim 13.

In a variant of the process, the blanket is a continuous band in motion.

In another variant of the process, the blanket is a sheet.

In all cases, the blanket may be integral with a carousel or a roller (for example a rubberized roller), or be arranged around at least one motorized flat pulley.

Optionally, the method also includes a step of measuring the circumference of the cylindrical printing medium.

In a variant, the method comprises a step of fixing the ink by applying a treatment on the ink.

This fixing step can be performed at least partially on the blanket.

PRESENTATION OF FIGURES

• les figures 1 et 2 illustrent différents modes de réalisation du dispositif selon l'invention,
• les figures 3 et 4 illustrent des exemples de supports d'impression,
• la figure 5 illustre un mode de réalisation d'un blanchet et d'un convoyeur,
• les figures 6 à 10 illustrent des exemples d'impressions réalisées sur des supports d'impression.

Other features, objects and advantages of the present invention will become apparent from the description which follows, which is purely illustrative and nonlimiting and should be read with reference to the accompanying drawings in which:

• the Figures 1 and 2 illustrate different embodiments of the device according to the invention,
• the Figures 3 and 4 illustrate examples of print media,
• the figure 5 illustrates an embodiment of a blanket and a conveyor,
• the Figures 6 to 10 illustrate examples of impressions made on print media.

DESCRIPTION OF THE INVENTION

With reference to the figure 1 an embodiment of the device according to the invention has been illustrated.

The device according to the invention is a transfer printing device on a printing medium. It is particularly suitable for printing cylindrical printing medium, preferably metal. For example, the printing medium 10 may be a container such as an aerosol or can.

In the embodiment illustrated in figure 1 the printing device comprises ink jet printing means 20, at least one blanket 30, a conveyor 40, and conveying means 50.

The printing means 20 allow the application, by spraying ink on the blanket 30, of the image to be reproduced on the cylindrical printing medium 10.

The image to be reproduced can be a motif and / or text. This image can be monochromatic or in color.

In the embodiment illustrated in figure 1 the printing means 20 comprise four printing heads Y, M, C, K capable of projecting distinct color inks. Thus, the printing means 20 illustrated in FIG. figure 1 allow the application of a color or monochrome image on the blanket 30.

The printing means 20 may comprise a plurality of printing heads Y, M, C, K capable of projecting inks. This makes it possible to increase the speed of application of the image on blanket 30.

In some embodiments, the printing means 20 may also comprise a single print head in the case where the device according to the invention is dedicated solely to the printing of monochromatic image on the printing medium 10 ( or a plurality of print heads capable of projecting ink of a single color).

Care should be taken to treat the image applied to the blanket (negative) so that it appears in the correct reading direction once transferred to the cylindrical printing medium (mirror effect).

The use of digital printing means allows a great flexibility in the application of the image to the blanket 30. In particular, the use of digital printing means makes printing cheaper because it is possible to customizing the print media without having to change the screen printing plates or plates at each image change, unlike techniques such as offset or pad printing, for example. Moreover, the use of digital printing means allows the application of an image on a variable surface.

The ink application can implement different application techniques depending on the size of the print medium 10 to be printed.

In one embodiment, the application technique used is a single-pass application technique.

In this case, the blanket 30 passes once under the print heads Y, M, C, K. The blanket 30 is for example disposed on the conveyor 40, a portion of the conveyor 40 being disposed under the printing heads. .

The conveyor moves in a direction of displacement D so that the surface of the blanket 30 for receiving the image to be transferred passes under the print heads Y, M, C, K.

The print heads Y, M, C, K project ink (or inks) onto the surface of the blanket 30: the image to be transferred onto the print medium 10 is applied to the surface of the blanket 30.

In another embodiment, the application technique used is a multi-pass application technique.

In this case, the blanket 30 must pass several times under the print heads Y, M, C, K so that the image is applied completely to the surface of the blanket 30.

The blanket 30 is an elastomeric material for the transfer of the ink onto the printing medium 10.

In the embodiment illustrated in figure 1 the device comprises two blankets 30. This makes it possible to increase the printing rate of the printing media 10. Of course, the device may comprise more than two blankets.

Each blanket 30 consists of a layer of material disposed on the conveyor 40.

As illustrated in figure 1 each blanket 30 has a surface greater than the surface of the cylindrical printing medium.

Even though each blanket 30 has a surface area greater than that of the printing medium 10, the area of the image applied to the blanket 30 by the digital printing means 20 is equal to that of the cylindrical printing medium 10.

This combination of at least one blanket having a surface greater than that of the printing medium and digital means 20 for printing on the blanket 30, an image on a surface equal to that of the printing medium 10 has many advantages.

On the one hand, it allows the transferred image to be properly closed on the cylindrical printing medium (i.e. the image transferred to the print medium is uninterrupted). So and as illustrated on the figure 3 for a cylindrical printing medium, this combination makes it possible to avoid that a zone Z1 of the support is not printed.

It also makes it possible to avoid the risks of recovering the transferred image on the cylindrical printing medium (that is to say, to prevent a portion of the image from overlapping with another portion of the image. the image). So, and as illustrated in figure 4 for a cylindrical printing medium, this combination makes it possible to prevent two portions of the image from being superimposed in a zone Z2.

This is not possible with offset technology.

• d'imprimer une image 11 sur la totalité de la face latérale du support d'impression 10,
• d'imprimer une image 12, 13, 14 sur une portion de la face latérale du support d'impression 10,
• d'imprimer plusieurs images 15, 16 sur différentes portions de la face latérale du support d'impression 10.

The device according to the invention allows the printing of a cylindrical support on the entire circumference of its side face. As illustrated in Figures 6 to 10 , the combination of digital printing means with a blanket whose dimensions are greater than those of the surface to be printed allows either:

• to print an image 11 on the whole of the lateral face of the printing medium 10,
• to print an image 12, 13, 14 on a portion of the lateral face of the printing medium 10,
• to print several images 15, 16 on different portions of the lateral face of the printing medium 10.

Thus, the combination of at least one blanket having a surface greater than that of the printing medium (and in particular having a face whose dimension is greater than the circumference of the printing medium) and digital printing means 20 allowing to apply, on the blanket 30, an image on a surface equal to that of the printing medium 10 (and in particular on a surface whose dimensions are equal to the circumference of the support) allows printing of the printing medium around its entire circumference by properly closing the transferred image and avoiding overlapping problems.

Of course, pieces of the printed image can be transparent. In this case, a transparent layer is applied on the support, the image then remaining continuous.

Moreover, this combination makes it possible to obtain a printing of better quality than with technology of the offset type.

Indeed, with offset technology, the application of the image on the blanket requires a blanket attack angle for friction between the blanket and the offset roll. At the start of such friction, the application of the image on the blanket induces a crash and therefore a lower quality of printing.

Finally, this combination allows the printing of cylindrical printing media 10 of different dimensions without having to change the blanket 30.

The conveyor 40 is a carousel and can support the blanket. However, the conveyor 40 may be of another type known to those skilled in the art.

Routing means 50 (i.e., the magazine carrying the print media) allow the conveyance of the cylindrical printing media. These routing means 50 are arranged downstream of the digital printing means 20.

The routing means 50 are of any type known to those skilled in the art.

The conveying means 50 are arranged to allow the printing surface of the cylindrical printing medium 10 to come into contact with the blanket 30 for the transfer of the image of the blanket onto the printing medium 10. movement of the conveyance means 50 is adapted to the cylindrical shape of the printing medium.

In the embodiment illustrated in figure 1 , the conveying means 50 comprise four mandrels extending along axes parallel to the axis of rotation of the conveyor 40. Each mandrel is able to receive a cylindrical printing medium 10, for example a bobbin or a bottle. Of course, the routing means 50 may comprise more than four mandrels. The conveying means may comprise means enabling the printing medium to be set in motion when it is printed, that is to say when it is in contact with the blanket. More specifically, the routing means may comprise an element (for example a motor) enabling the printing medium to rotate when it is in contact with the blanket.

Optionally, the device may also comprise fixing means 60, a varnishing block 70 and cleaning means 80.

The fastening means 60 allow the image applied to the blanket 30 to be dried, for example by heating or by crosslinking (application of infrared or ultraviolet radiation). These fixing means are arranged downstream of the digital printing means 20, and upstream of the conveying means 50 in the direction D. The fastening means 60 are of any type known to those skilled in the art.

The paint block 70 is a system for depositing a layer of varnish on the blanket 30 after the transfer of the image onto the print medium has been performed. This layer of varnish serves to protect the transferred image on the print medium.

This varnishing block 70 is of any type known to those skilled in the art.

The varnishing block 70 may be arranged upstream or downstream of the conveying means 50 in the direction D.

The cleaning means 80 allow the surface of the blanket 30 to be cleaned. These cleaning means 80 may be arranged upstream or downstream of the conveying means 50 in the direction D of displacement of the conveyor 40.

The operating principle of the device illustrated in figure 1 is the next.

The conveyor 40 moves in rotation in the direction D.

The blanket 30 disposed on the conveyor passes under the printing heads Y, M, C, K digital printing means 20. The print heads project ink on the blanket 30 so as to apply the image on this one. Depending on the application technique used (single-pass / multi-pass), the blanket 30 passes one or more times under the print heads for the application of the image.

Once the image is applied, the blanket 30 passes under the fixing means 60 which partially dry the image applied to the blanket 30. In the case of a multi-pass application technique, the fixing means can partially dry the ink applied to the blanket after each pass.

The blanket 30 passes under the conveyance means 50 which moves so that a cylindrical printing medium 10 comes into contact with the blanket 30.

When the blanket and the printing medium are in contact, the blanket and the print medium may be in relative motion relative to one another. More specifically, when the blanket and the printing medium are in contact, the blanket is moving relative to the printing medium, and the printing medium is moving relative to the blanket. In one embodiment, the blanket and the printing medium are both rotated when in contact. This allows the printing of the blanket throughout its circumference continuously.

• sous l'action du blanchet grâce aux forces de friction exercées par le blanchet en mouvement sur le support d'impression,
• sous l'action d'un élément disposé sur les moyens d'acheminement et permettant la mise en rotation du support d'impression.

Advantageously, when the blanket and the printing medium are in contact, the printing medium can be rotated:

• under the action of the blanket due to the frictional forces exerted by the moving blanket on the printing medium,
• under the action of an element disposed on the conveying means and allowing the printing medium to rotate.

The image is transferred to the cylindrical printing medium.

Optionally, the blanket 30 passes in front of the varnishing block 70 which applies a coating layer to the blanket 30.

The conveyor 40 moves so that the blanket 30 passes again under the conveyor means 50: in the case of a cylindrical conveyor 40, the blanket begins a second turn around the axis of the conveyor.

The conveying means 50 moves towards the blanket 30 so that the cylindrical printing medium 10 on which the image has been transferred comes into contact with the blanket 30: the lacquer layer is transferred onto the blank. 10 cylindrical printing.

The conveyor 40 moves the blanket 30 so that it passes under the cleaning means 80 which cleans the surface of the blanket 30.

With reference to the figure 2 another embodiment of the device according to the invention has been illustrated.

The differences between the embodiments illustrated in Figures 1 and 2 concern the blanket 30.

In the embodiment illustrated in figure 2 blanket 30 is a single continuous band.

In the context of the present invention, the term "continuous" means a blanket whose face intended to receive the inks to be printed is uninterrupted in at least one direction. In other words, "continuous" blanket means a blanket closed on itself.

The combination of the digital printing means with a continuous single blanket makes it possible - in addition to the advantages previously described in the case of a blanket whose surface is greater than that of the printing medium - to increase the printing rate per minute. an optimization of the use of the circumference of the conveyor 40.

Où:

• CADENCE : correspond à la cadence d'impression,
• nb_blanchets : correspond au nombre de blanchets sur le convoyeur,
• vitesse_défilement : correspond à la vitesse de défilement des blanchets qui est actuellement limitée par la vitesse d'impression jet d'encre (24 m/min),
• périmètre_convoyeur : correspond au périmètre du convoyeur dans le cas d'un convoyeur de type carrousel.

Indeed, the rate of printing is given by the following formula: $$\mathit{CADENCE}=\frac{\mathit{nb\_blanchets}\times \mathit{vitesse\_défilement}}{\mathit{périmètre\_convoyeur}}$$

Or:

• CADENCE: corresponds to the print rate,
• nb_blanchets: corresponds to the number of blankets on the conveyor,
• scrolling speed: corresponds to the speed of scrolling blankets which is currently limited by the speed of inkjet printing (24 m / min),
• Conveyor perimeter: corresponds to the perimeter of the conveyor in the case of a carousel type conveyor.

Thus, the fact that the device comprises a continuous single blanket makes it possible, by means of processing means (not shown) of the device, to determine the maximum number of images that can be applied to the continuous blanket, as a function of the surface of the cylindrical printing medium.

This makes it possible to limit the areas of the conveyor 40 which are not used for printing the cylindrical printing media and thus to optimize the print rate according to the dimensions of the cylindrical printing medium.

In the embodiment illustrated in figure 1 , the blanket 30 consists of a sheet of material disposed on one face of the conveyor 40. In the embodiment illustrated in FIG. figure 2 , the blanket consists of a continuous strip disposed on the conveyor.

However, the invention is not limited to this type of blanket. Indeed, in another embodiment, the blanket 30 is a rubber roller.

The figure 5 illustrates another embodiment of blanket 30 and conveyor 40.

In this embodiment, the conveyor 40 is composed of a motorized flat pulley comprising a flat rim 41 around which is disposed the web-shaped continuous blanket.

The device according to the invention may also comprise means capable of measuring the circumference of the cylindrical printing medium so that the processing means precisely adjust the dimensions of the image relative to those of the surface to be printed.

This allows the tolerance (permissible variation in the dimensions of the print media) to be taken into account on this print medium, since the amplitude of the print media may vary from one print medium to another.

According to a nonlimiting embodiment variant developed by IMPIKA, the device may comprise means for applying a liquid receiving layer to the blanket 30.

The means for applying a liquid receiving layer can be application means by contact (in particular by offset), by pressure spray (spray technology), or by ink projection (inkjet technology). .

The use of inkjet application means for deposition of the receiving layer makes it possible to better control the quantity of liquid material projected onto the blanket 30, and thus to better control the thickness of the receiving layer in order to to optimize the quality of the final print.

The thickness of the liquid receiving layer is typically but not limited to between 2 and 80 μm. It will be noted that, preferably, the thickness of the liquid receiving layer is greater than the diameter of the ink drops applied by the digital printing means.

The application of the image on the blanket can be performed before or after the deposition of the liquid receiving layer.

The liquid receiving layer facilitates the transfer of the image onto the cylindrical printing medium.

• rester à la surface de la couche de réception,
• être captées dans la couche de réception.

According to the physical properties of the receiving layer, when the ink is projected onto the receiving layer previously applied to the blanket 30, the ink drops projected on the face of the blanket will either:

• stay on the surface of the receiving layer,
• be captured in the receiving layer.

When the receiving layer is able to capture the drops of ink projected on the face of the blanket, this receiving layer prevents two different drops from mixing.

The presence of means for the application of a liquid receiving layer has many advantages, especially when the direct printing on the cylindrical printing medium is impossible for mechanical reasons or other (impossibility to place the printing device sufficiently close to the print medium, non-flat print media, etc.).

According to a nonlimiting, but advantageous, implementation of the present invention, the liquid receiving layer and the ink are of different chemical natures so that their attachment or drying can be operated using different respective processes. Thus fixing or drying one does not affect the other.

In particular, it is possible to fix the ink before fixing the liquid receiving layer. In this case the fixing of the ink is performed in a receiving layer still in the liquid state. This makes it possible to control a certain diffusion of the ink within the receiving layer. This allows in particular a good final resolution of the printing, a good rendering of colorimetry and a printing constant over time.

As a variant, however, and in particular depending on the desired final printing result, it is conceivable to fix the ink after the liquid receiving layer.

In the various embodiments of the device, the conveyor is cylindrical, the conveyor means 50 and the conveyor being each movable in rotation. However, it is possible to envisage a planar conveyor and conveyance means that are moved opposite one another.

Claims (13)

1. Device for printing by transfer onto a cylindrical printing medium (10), the device including at least one offset blanket (30) which is driven with a relatively sequential motion in front of a magazine (50) bearing the cylindrical printing media (10),
   characterised in that the offset blanket (30) has a surface that is greater than the surface of the printing medium (10) and in that the device further includes means for digital printing (20) by projection of ink onto this offset blanket (30) onto a variable surface that is equal to the surface of the printing medium (10) and processing means that are designed to fit the dimensions of the image applied onto the offset blanket (30) in accordance with the circumference of the printing medium (10) so that the image covers the circumference of the lateral face of the cylindrical printing medium, without overlap.
2. Device according to claim 1, characterised in that the offset blanket (30) is a continuous single strip in motion.
3. Device according to either of claims 1 or 2, characterised in that the offset blanket (30) is a sheet.
4. Device according to one of claims 1 to 3, characterised in that the offset blanket (30) is fixed to a carrousel (40) or a rubber roller.
5. Device according to either of claims 1 or 2, characterised in that the offset blanket (30) is placed around at least one motor-driven flat pulley.
6. Device according to one of claims 1 to 5, characterised in that the device also includes means for measuring the circumference of the printing medium (10).
7. Device according to one of claims 1 to 6, characterised in that the means for digital printing (20) by the projection of ink include a multiplicity of printing heads (Y, M, C, K) that are positioned so that the distance separating a printing head from the offset blanket (30) is constant.
8. Device according to one of claims 1 to 7, characterised in that the device also includes means for fixing (60) the ink by the application of a treatment to the ink.
9. Device according to claim 8, characterised in that the means for fixing (60) the ink are designed to fix the ink partially onto the offset blanket (30).
10. Device according to one of the previous claims, characterised in that the printing medium is driven in rotation when said printing medium and the offset blanket are in contact.
11. Device according to claim 10, characterised in that the printing medium is driven in rotation by the offset blanket when said printing medium and offset blanket are in contact.
12. Device according to claim 10, characterised in that the printing medium is driven in rotation by an element of the transportation means, where said element being used to set the medium into rotation when said medium and the offset blanket are in contact.
13. Method for transfer printing onto a cylindrical printing medium comprising:

    - application of an image onto a offset blanket (30) that is driven with a relatively sequential motion in front of a magazine (50) bearing cylindrical printing media (10),

    - transfer of the image onto the cylindrical printing medium (10) by contact of the offset blanket (30) with said medium (10),

    characterised in that
    the surface of the offset blanket (30) is greater than the surface of the cylindrical printing medium (10), the image being applied onto the offset blanket (30) by projection of ink using digital printing means (20) onto a variable surface that is equal to the surface of the cylindrical printing medium (10), the dimensions of the image applied on the blanket (30) being designed to fit the circumference of the printing medium so that the image covers the circumference of the lateral face of the cylindrical printing medium, without overlap.

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