METHOD AND DEVICE FOR PRINTING OR DECORATING AN OBJECT

Description

[0001] The invention relates to a method for printing or decorating an object which has at least one uneven, in particular convex or concave shaped, printing surface which is printed with at least one print image, wherein for printing the printing surface the print image is generated by means of at least one print head on an image transfer surface of an image transfer element and the print image is then transferred to the printing surface by pressing the image transfer surface onto the printing surface.

[0002] Furthermore, the invention relates to a device for printing or decorating an object, which device has at least one print head and at least one image transfer element, wherein a print image can be generated on an image transfer surface of the image transfer element by means of the print head and the print image generated on the image transfer surface can be transferred to the printing surface by pressing the image transfer surface onto an uneven, in particular convex or concave, printing surface of the object. STATE OF THE ART

[0003] Methods and devices of the type mentioned above are generally known from the prior art, see for example US 2003 / 0136281 A1, EP 2 756 959 A1.

[0004] A method and a device according to the preamble of claims 1 and 11 respectively are known from US 2016 / 0279973 A1.

[0005] The patent US 8,800,439 B2 discloses a method and a corresponding device known under the brand name "PadJet" from the US company Paedia LLC. The method and device are used to print an uneven printing surface of an object, for example, a ball, with a printed image. The known method uses transfer printing, in which the printed image is first generated by a print head on a surface of an image transfer element, i.e., an image transfer surface, and is then transferred by the image transfer element to the surface of the object to be printed by pressing the image transfer surface into contact with the surface to be printed. In this respect, the known method is a transfer printing method.

[0006] In the previously mentioned known method, the corresponding device implementing the method is designed as a rotary printing device. In this rotary printing device, several image transfer elements designed as press stamps are arranged to rotate about a common axis of rotation and are aligned such that the respective image transfer surfaces point away from the axis of rotation and can thus be assigned to or turned towards a print head or the printing surface of the object to be printed. In the known device, the print head is arranged in a defined position, in particular immovably. Figuratively speaking, the print head is arranged above the rotating image transfer elements. By rotating the image transfer elements, they are moved one after the other below the print head, whereby the print head applies the print image to the respective image transfer surface.Offset by 180° around the axis of rotation, i.e. figuratively speaking, below the rotating image transfer elements, a conveyor belt is arranged on which objects, each with a printing surface to be printed, are moved along the rotating image transfer elements. By further rotating the image transfer elements, the image transfer surface is moved to one of the objects after the print image has been applied in order to bring the image transfer surface into contact with the printing surface for transferring the print image. Essentially, this is done by rolling the image transfer element onto the object, whereby the image transfer surface is pressed onto the printing surface and thus the print image is transferred. In another embodiment, the image transfer element is in the form of an endless loop-shaped belt running over two rollers, on which belt the print image is generated by means of the print head.It is then transferred from the tape to the object to be printed.

[0007] EP 3 633 453 A1 discloses a device and a method for producing microstructures on curved surfaces of an optical component. For this purpose, a structured molding film is formed on a composite of an elastic carrier film and a reinforcing film in a complex process by applying a molding compound to the carrier film and embossing it using a microstructured mold. A UV-curable substrate compound is applied thereon, and after the reinforcing film is removed, the optical component to be coated is pressed against the substrate compound, whereby the elastic carrier film adapts to the component. In this state, the substrate compound is cured and then detached from the carrier film together with the component.

[0008] The object of the present invention is to provide an improved method of the type mentioned above or an improved device.

[0009] This object is achieved by a method having the features of claim 1 and a device having the features of claim 10. Advantageous embodiments of the invention are the subject of the dependent claims. DISCLOSURE OF THE INVENTION

[0010] In the method having the features of claim 1, the invention provides that an exchangeable print image intermediate carrier with a holding frame and with a film, in particular a silicone rubber film, which is held in a flat, tensioned, in particular pre-tensioned, manner in the holding frame and has the image transfer surface is used as the image transfer element, and that the pressing of the image transfer surface is carried out by means of at least one displaceable, in particular elastically deformable or fillable with a fluid, in particular compressed air, pressing device, wherein a surface of the film opposite the image transfer surface is subjected to a preset pressing pressure by the pressing device in order to press the image transfer surface against the printing surface and thereby transfer the print image from the image transfer surface to the printing surface.In this respect, in a device specially designed to carry out the method according to the invention, the image transfer element is designed as a replaceable print image intermediate carrier with a holding frame and with a film, in particular a silicone rubber film, which is held in a flat, particularly pre-tensioned manner in the holding frame and has the image transfer surface, wherein the pressing of the image transfer surface can be carried out by means of at least one displaceable, particularly elastically deformable or fillable with a fluid, in particular compressed air, pressing device, wherein a surface of the film opposite the image transfer surface can be subjected to a preset pressing pressure by the pressing device in order to press the image transfer surface against the printing surface and thereby transfer the print image from the image transfer surface to the printing surface.In particular, during the pressing, a surface, in particular a pressing surface, of the pressing device is deformed at least in some regions in such a way that it is complementary to the pressure surface.

[0011] Preferably, printing surfaces made of plastic, i.e., plastic printing surfaces, are printed using the method according to the invention. Naturally, however, the method according to the invention is also suitable for printing on printing surfaces made of other materials, for example, metal or wood. When pressed, the film adapts automatically, flexibly, and precisely to the surface geometry of the printing surface, so that even geometrically comparatively odd-shaped or complex printing surfaces can be printed with precision. The method according to the invention thus advantageously ensures individual adaptation of the image transfer surface to the geometry of the printing surface and thus high-quality printing on the printing surface.Furthermore, the pressing device enables precise and precisely controllable pressing, particularly by means of the adjustable pressure and a correspondingly selected displacement or positioning during pressing. Air pockets that can arise when the image transfer surface is pressed against the printing surface are thereby advantageously substantially avoided, further optimizing the quality of the transferred, i.e., finished, printed image. In this respect, the method according to the invention enables simple, high-quality, and cost-effective printing of the object. Furthermore, the method according to the invention allows the printed image, in particular a multi-colored printed image, to be generated or transferred to the printing surface in a single work step.A digital print head is used as the print head, with the print image being generated by the digital print head using a digital printing process, in particular an inkjet process. Therefore, in the device specifically designed for carrying out the method according to the invention and having a corresponding print head, the print head is designed as a digital print head, which is designed to generate the print image using a digital printing process.

[0012] With conventional processes, in particular pad printing processes, it is often necessary to produce a multi-colored print image in several sequential work steps using several printing pads, with each printing pad being assigned to a single color of the print image. This results in a comparatively high level of effort in producing the print image, in particular due to the precise mechanical alignment of the printing pads required. The digital print head, in contrast, offers the advantage that several colors can be transferred simultaneously, so that a multi-colored print image can be created in a single work step. In addition, the print image can be created or transferred to the printing surface in high resolution, in particular with an accuracy of up to 5000 dpi. It is therefore particularly preferred to produce the print image as a multi-color print image and transfer it to the printing surface in a single step.This has the overall advantage that the print image can be produced easily and cost-effectively, with high quality.

[0013] It is particularly preferred that, before pressing, the printed image is subjected to a radiation treatment to increase the viscosity of the printed image, and that a highly pigmented ink, in particular one that can be cured by means of LED, UV or infrared light, is used for the printed image.

[0014] In this respect, the device specifically designed to carry out the method according to the invention is preferably designed to subject the printed image to a heat treatment prior to pressing to increase its viscosity. The printed image comprises a highly pigmented ink, particularly one curable by LED, UV, or infrared light. The ink is preferably plastic-based, with the quantity or size of individual ink drops preferably being in the range of 1 to 2 picoliters per pixel. The radiation treatment is preferably carried out using microwave, LED, or UV lamps, with an irradiation time preferably selected in the nanosecond range.The setting of the specific parameters of the radiation treatment, in particular the irradiation time, is carried out individually depending on the respective specific application, in particular depending on the size and / or color composition of the printed image and / or the properties of the printing surface. By increasing the viscosity, the risk of a deterioration in quality, in particular bleeding, smearing, or smearing of the printed image, particularly during pressing or transfer to the printing surface, is advantageously reduced, or in particular avoided. The use of a highly pigmented and, in particular, curable ink ensures a high-quality printed image and, in particular, a simple and cost-effective radiation treatment to increase viscosity.

[0015] Preferably, the intermediate print image carrier is pivoted, in particular by 180°, by means of a pivoting device before being pressed on. Therefore, the device specifically designed to carry out the method according to the invention is particularly configured to pivot the intermediate print image carrier, preferably by 180°, by means of a pivoting device. Preferably, in the method according to the invention, both the generation of the print image on the image transfer surface and its transfer to the printing surface take place spatially downwards, i.e., in the direction of the gravitational force, so that, in particular, the gravitational force prevents clogging of the nozzles of the digital print head and, in addition, ensures improved transfer of the print image to the printing surface.The pivoting or pivotability of the image transfer element offers the advantage that the image transfer surface can be assigned to the print head or the printing surface as needed in a technically particularly simple manner, so that the print head, in particular, can always remain in a fixed position, resulting in a technically simple implementation of the method or device design. In the context of the present invention, pivoting is understood to mean both tilting by preferably 180°, as well as moving away or rotating away on the same horizontal or vertical plane. The pivoting device can be electromechanical, pneumatic, or mechanical.

[0016] The film is preferably made of a stretchable and tear-resistant material, in particular silicone rubber or silicone elastomer, in particular ELASTOSIL®, or latex, with the film being stretched in the holding frame with a Shore hardness in the range of 2 to 20 Shore. Therefore, the film preferably comprises a stretchable and tear-resistant material, in particular silicone rubber or silicone elastomer, in particular ELASTOSIL®, or latex.

[0017] This allows the intermediate print image carrier to be produced with particularly economical use of material. The film has particularly advantageous material properties that reliably ensure secure transfer of the print image and thus high-quality printing on the printing surface. The brand name ELASTOSIL ®< refers to a product from Wacker Chemie AG in Germany. This is a film made of cross-linked silicone rubber with a layer thickness of between 20 and >400 µm. The term Shore grade or the so-called Shore hardness refers to a material value defined in the standards DIN EN ISO 868, DIN ISO 7619-1 and ASTM D2240-00 for elastomers and plastics to characterize their elastic properties. In this case, an elastomer film is preferably used or the film is designed as an elastomer film. The maximum thickness of the film is preferably 2 mm.Particularly preferably, the material properties of the film are selected individually depending on the respective application, which means in particular that the film is manufactured or at least selected specifically for the respective application.

[0018] For production, the film is cast, for example, from a starting liquid, in particular a 2K or multi-component liquid. The film preferably has hydrophilic or hydrophobic properties. In particular, the film's Shore hardness is in the range of 0.3 to 20, preferably 2 to 15, Shore. Therefore, the film in the holding frame is preferably prestressed to 0.3 to 20, in particular 2 to 15, Shore, with the prestress being selected, in particular, depending on the specific application.

[0019] According to a preferred development, the pressing device used is a pressing head formed at least partially from an elastomer material, in particular gelatin or silicone, and displaceable in the direction of the film, with an elastically deformable pressing surface, which is in particular convex in an initial state. In this respect, a pressing device of the device specifically designed to carry out the method according to the invention preferably has a pressing head formed at least partially from an elastomer material, in particular gelatin or silicone, and displaceable in the direction of the film, with an elastically deformable pressing surface, which is in particular convex in an initial state.This embodiment offers the advantage that, when pressed, the pressure surface, with the foil interposed, continuously and precisely conforms to the geometry of the printing surface from a starting point, allowing the print image to be transferred to the printing surface reliably and essentially without air pockets and the associated loss of quality. The pressure head is preferably replaceable to allow for individual adaptation to the specific application. Silicone or fine-grained foam, especially microfoam, is preferably used as the elastomer material.

[0020] According to an alternatively preferred development, a balloon that can be filled or is filled with a fluid, in particular compressed air, is used as the pressing device. In this respect, the pressing device of the device specially designed for carrying out the method according to the invention is alternatively preferably designed as a balloon that can be filled or is filled with a fluid, in particular compressed air. As a result, the pressing device is technically comparatively simple in design and can therefore be manufactured particularly cost-effectively. The balloon is made of a tear-resistant yet elastic material, preferably latex or silicone. The maximum material thickness is preferably 1 mm. Compressed air is preferably used as the fluid, but a liquid is also possible alternatively. The fluid is preferably conveyed into and out of the balloon by means of a conveying device.In this respect, the device designed to carry out the method according to the invention preferably has a conveying device for conveying the fluid. Alternatively, the balloon is preferably already filled with the fluid, with the amount of fluid remaining constant. Preferably, the balloon is assigned a pneumatic control system by means of which the pressure can be adjusted.

[0021] According to a further alternative preferred development, a compressed air chamber that can be filled with compressed air and is delimited or co-formed by the film is used as the pressing device. In this respect, the pressing device of the device specially designed for carrying out the method according to the invention is alternatively preferably designed as a compressed air chamber that can be filled with compressed air and is delimited or co-formed by the film. This exemplary embodiment offers the advantage that the film can be subjected to the pressing pressure particularly evenly and yet in a targeted manner. Preferably, a base body of the compressed air chamber is essentially trough-shaped, wherein the intermediate printed image carrier can be connected to the base body in a sealing manner like a lid, for example, can be locked to the base body, so that the film or the intermediate printed image carrier forms the compressed air chamber with the base body.In this respect, the film also forms the compressed air chamber. Alternatively, it is also conceivable for the base body to be closed, with a single flexible wall that can be curved outward when pressurized and assigned to the intermediate print image carrier or the film. In this case, the film can be placed on the outside of the flexible wall, with the flexible wall being limited by the film during the outward curvature.

[0022] In particular, it is provided that the intermediate print image carrier is mounted in a movable and / or replaceable manner in a bearing device. Therefore, in the device specifically designed for carrying out the method according to the invention, the intermediate print image carrier is preferably mounted in a movable and / or replaceable manner in a bearing device. This provides the advantage that the intermediate print image carrier can be replaced particularly easily when needed, particularly in the event of damage or for adjustment purposes. Furthermore, the movable mounting allows for increased flexibility when printing on the printing surface.For example, the bearing device is designed as a locking device, wherein a locking lug or a locking receptacle of the bearing device interacts with a locking receptacle or locking lug of the intermediate print image carrier, in particular its holding frame, to enable easily detachable yet secure mounting of the intermediate print image carrier. Preferably, the bearing device is formed integrally with the pivoting device described above.

[0023] According to the invention, during the generation of the printed image on the image transfer surface, the film is supported and thereby prestressed by a support element that can be displaced in the direction of the surface opposite the image transfer surface. Therefore, the device specifically designed for carrying out the method according to the invention is designed to support and thereby prestress the film during the generation of the printed image on the image transfer surface by means of a support element that can be displaced in the direction of the surface opposite the image transfer surface. This support has the advantage of ensuring sufficient tension or prestress of the film, thus guaranteeing high-quality production of the printed image.

[0024] The device with the features of claim 10 has at least one print head and at least one image transfer element, wherein a print image can be generated on an image transfer surface of the image transfer element by means of the print head, and the print image generated on the image transfer surface can be transferred to the printing surface by pressing the image transfer surface onto an uneven, in particular convex or concave, printing surface of the object. The device is characterized in that it is specifically designed to carry out the previously discussed method as described. This results in the advantages already mentioned in this regard. With regard to advantageous embodiments and definitions, reference is made in full to what has already been described.

[0025] As already described above, it is particularly preferred that the image transfer element is designed as an interchangeably mounted intermediate print image carrier with a holding frame and with a film, in particular a silicone rubber film, held in a flat, tensioned, in particular pretensioned, manner in the holding frame, and that the device has a pressing device, in particular elastically deformable or fillable with a fluid, in particular compressed air, for pressing the film and / or a bearing device, in particular integrally formed with the pressing device, for movable and / or interchangeable mounting of the intermediate print image carrier. Here, too, the advantages already mentioned in this regard arise.

[0026] Preferably, the device comprises a pivoting device for pivoting the film. The corresponding advantages and configurations have already been discussed above.

[0027] According to the invention, the device comprises a support element that can be displaced in the direction of the film for supporting or tensioning the film. The above description applies in this regard.

[0028] The image transfer element, in particular the intermediate print image carrier, has a holding frame and a film clamped in the holding frame and is specifically designed for use in the device already discussed above. The intermediate print image carrier is a prefabricated element that can be used in the device specifically prepared for carrying out the method according to the invention, the properties of which, in particular the thickness and / or pre-tension of the film, can be or are individually adapted to the requirements of the respective object to be printed or its corresponding printing surface. The holding frame is preferably made of plastic, wood, or metal, with the film firmly clamped in the holding frame, i.e., permanently fastened in or to it, for example, welded.Preferably, the film is alternatively held in the holding frame in a non-destructive, releasable manner, for example, releasably clamped or clipped. Particularly preferably, the holding frame is designed such that it has only curved, i.e., no angled, corners, thus avoiding stress peaks in the film and thus maintaining a substantially uniform tension over the entire circumference of the holding frame. Therefore, the holding frame preferably has a round or oval cross-section. In particular, the diameter of the holding frame is 100 mm to 300 mm. DRAWINGS

[0029] Further advantages will become apparent from the accompanying drawings, which illustrate exemplary embodiments of the invention.

[0030] They show: Fig. 1 a schematic flow diagram of an advantageous method, Fig. 2A to 2Da simplified representation of an advantageous device for carrying out the method according to a first embodiment, Fig. 3A to 3D a simplified representation of the device according to a second embodiment, Fig. 4A to 4D a simplified representation of the device according to a third embodiment not according to the invention.

[0031] In the figures, similar elements are numbered with the same reference numerals. The figures are merely examples and are not to be construed as limiting.

[0032] Figure 1 shows a schematic flow diagram of an advantageous method for printing or decorating an object. The process sequence will be explained below by way of example with reference to Figures 2A to 2D will be explained in more detail. Figures 2A to 2Din a simplified representation, a cross section through a first embodiment of an advantageous device 1 specially prepared for carrying out the method, in each case at different times of the method.

[0033] The Figures 2A to 2DThe device 1, shown in simplified form, has a print head 2 and an image transfer element 3 with an image transfer surface 4. The print head 2 in the present case is a digital print head 2 which is designed to produce a multi-colored print image 5 in a single work step by means of a digital printing process. For example, the digital print head 2 is an inkjet printer which produces the print image 5 from a highly pigmented ink 5' which is preferably curable by means of LED, UV or infrared light and is in particular plastic-based. The image transfer element 3 in the present case is advantageously designed as an intermediate print image carrier 6 which has a holding frame 7, made in particular of plastic or metal, in which a film 8 having the image transfer surface 4 is held in a flat, tensioned, in particular pre-tensioned, manner.Preferably, the film 8 is firmly connected to the holding frame 7, for example welded or glued.

[0034] Optionally, however, the film 8 can also be held in the holding frame 7 in a non-destructively releasable manner, for example releasably clamped. In the present case, the holding frame is designed to be edge-free, in particular oval, i.e. it has - if any - only curved, but no angled corners, so that the film 8 is stretched essentially evenly over the entire circumference of the holding frame 7. In the present case, the film 8 is made as an elastomer film made of an extensible and tear-resistant material such as silicone rubber or silicone elastomer, in particular ELASTOSIL ®<, or latex. In the present case, the film has a maximum thickness of 2 mm and, depending on the specific application, is stretched in the holding frame 7 with a Shore hardness of 2 to 20.

[0035] The device 1 further comprises a bearing device 9, shown here only as an example, which is designed to mount the image transfer element 3, or the intermediate print image carrier 6, movably and / or replaceably in the device 1. In this respect, the intermediate print image carrier 6 is mounted movably and / or replaceably in the device 1. For this purpose, the bearing device 9 is preferably designed as a locking device, wherein a locking lug (not shown here) or a locking receptacle of the bearing device 9 interacts with a locking receptacle or locking lug (likewise not shown here) of the intermediate print image carrier 6, in particular of its holding frame 7.In addition, the device 1 according to the present embodiment has a pivoting device 10, which is formed in particular integrally with the bearing device 9 and by means of which the intermediate print image carrier 6 can be pivoted, in particular, by 180°, as will be explained in more detail later. Optionally, however, the pivoting device 10 can also be omitted. In the present case, the pivoting device 10 is designed electromechanically, pneumatically, or mechanically.

[0036] The process begins in a first step S1, which is Figure 2Ais shown by way of example. In this case, the multi-colored print image 5 is generated in a single work step by means of the digital print head 2 on the image transfer surface 4 of the image transfer element 3 or the film 8 of the print image intermediate carrier 6. In this respect, at least in step S1, the print image intermediate carrier 6 is arranged in the device 1 or mounted in the storage device 9 in such a way that the image transfer surface 4 faces the digital print head 2 and a surface 12 of the film 8 opposite the image transfer surface is applied by the digital print head 2.

[0037] According to the present embodiment, the printed image 5 is generated by means of a digital printing process, wherein the digital print head 2 generates the highly pigmented and, in particular, curable ink 5' forming the printed image 5 in a single-phase or multi-phase printing process on the image transfer surface 4. Individual ink drops of the ink 5' are applied with a respective size or ink quantity of 1 to 2 picoliters per pixel. For this purpose, the digital print head 2 is moved, in particular, several times over the image transfer surface 4, as shown in Figure 2Ais illustrated by way of example using a first arrow 11. Alternatively, however, the digital print head 2 can also be fixed, and the print image intermediate carrier 6 is moved along the digital print head 2. In this case, the print image intermediate carrier 6 is at least movably mounted in the bearing device 9. In the present case, the print image 5 is created entirely in a single work step, with the ink 5' being applied downwards, i.e. in the direction of gravitational force, in order to avoid clogging of the nozzles of the digital print head 2.

[0038] The film 8 is held in place during the application of the printed image 5 to its image transfer surface 4 by a Figure 2AThe support element 13 is supported by a dashed support element 13, in particular to ensure sufficient tension or pre-tension of the film 8. For this purpose, the support element 13 is displaceable in the direction of the surface 12 opposite the image transfer surface 4, as shown in Figure 2A is shown by a dashed second arrow 14.

[0039] After the print image 5 has been generated on the image transfer surface 4, the print image 5 is subjected to a radiation treatment in an intermediate step S1.1, whereby the ink 5' gels and thereby increases the viscosity of the print image 5. This advantageously prevents, in particular, any running of the ink 5' and thus any deterioration in the quality of the print image 5. During the radiation treatment, the curable ink 5' is irradiated in pulsed fashion using a radiation source, for example at least one microwave, LED, or UV lamp, with an irradiation duration in the nanosecond range. The parameters of the radiation treatment are selected individually depending on the respective application, i.e., in particular, depending on the selected ink 5', the size of the print image 5, and / or the properties of the film 8.The parameters are selected or adjusted in such a way that a problem-free separation of the individual ink droplets, i.e. the printed image 5, from the image transfer surface 4 is ensured.

[0040] Figure 2B shows, by way of example, a simplified representation of the device 1 during a next step S2. In step S2, the print image intermediate carrier 6 according to the present embodiment is pivoted by preferably 180° by means of the pivoting device 10, as in Figure 2Bexemplified by third arrows 15, and thereby facing away from the digital print head 2. Subsequently, by means of a pressure device 16 of the device 1, which will be explained in more detail later, the surface 12 of the film 8 opposite the image transfer surface 4 is subjected to a preset pressure 17. Spatially speaking, the pressure is applied downwards, i.e. in the direction of the gravitational force. As shown in Figure 2C As shown, this application serves to press the image transfer surface 4, which now faces a printing surface 18 of an object 19 to be printed, against the printing surface 18 in a further step S3 and thereby to transfer the printed image 5 onto the printing surface 18 or the object 19. As shown in Figure 2CAs can be clearly seen, during the pressing process, a surface of the pressing device is deformed, at least in part, in such a way that it is complementary to the printing surface, i.e., conforms evenly to the printing surface. As a result, the film 8 is evenly subjected to the pressing pressure 17. The bearing device 9 and / or the pivoting device 10 are designed such that, during the pivoting process, they ensure precise fixing or adjustment of the intermediate print image carrier 6, in particular with an accuracy of at least 1 µm, in order to ensure exact transfer of the print image 5 to the printing surface 18. The setting of the pressing pressure 17, i.e., in particular the selection of the magnitude and / or duration of the application, is carried out depending on the respective properties of the film 8, ink 5' and / or the printing surface 18 or the object 19.Optionally, the object 19, in particular the printing surface 18, is pretreated, preferably cleaned and / or electrostatically discharged, before pressing, i.e., in particular before step S2 or S3, in order to ensure optimal transfer of the printed image 5 or the ink 5'. For example, the printing surface 18 is subjected to an ionization air jet to discharge the printing surface 18. Subsequently, in a final step S4, which is shown in . Figure 2D As shown, the finished printed object 19 is obtained, which thus has the printed image 5 on its printing surface 18. In this case, the printing surface 18 is made of plastic, thus it is a plastic surface. However, other types of printing surfaces 18 can also be advantageously printed using the method described above.

[0041] The use of the intermediate print image carrier 6 ensures, in particular through the film 8, optimal adaptation to the surface geometry of the printing surface 18 in order to ensure a precise transfer of the print image 5 and thus high-quality printing of the object 19. Since the intermediate print image carrier 6 is replaceable, the method and device 1 described above continue to ensure a high degree of flexibility with regard to adaptations to the respective printing requirements of the object 19 to be printed.In this respect, the printing properties of the method or of the device 1 can be individually adapted to the object 19 to be printed by a simple exchange of the print image intermediate carrier 6, wherein the properties of the print image intermediate carrier 6, i.e. in particular the material properties of the film 8 and / or its degree of pre-tension, are also individually adaptable or are adapted.

[0042] As in Figures 2C and 2DAs can be seen, the object 19 to be printed is shown as spherical, so that the printing surface 18 is convex. However, this is only an example to illustrate the invention. Of course, with the present advantageous method or the advantageous device 1, a printing surface 18 with a concave shape or a different surface geometry can also be printed with the print image 5. In this respect, the present invention is not limited to printing convex printing surfaces 18.

[0043] Optionally, pivoting the print image intermediate carrier 6 can be omitted in step S2. In this case, to direct the image transfer surface 4 away from the digital print head 2 or to direct the image transfer surface 4 toward the printing surface 18, the digital print head 2 can, for example, be moved away and the object 19 can be arranged at the previous position of the digital print head 2. It is also conceivable to rotate the print image intermediate carrier 6 toward the object 19 without pivoting.

[0044] According to the Figures 2A to 2DIn the first exemplary embodiment of the device 1 shown, the pressing device 16 has a pressing head 20 that can be displaced in the direction of the film 8. The device 1 accordingly has displacement means (not shown here) that enable the displacement of the pressing head 20, wherein the pressing pressure 17 can also be adjusted, in particular by means of the displacement means. The pressing head 20 is made at least partially from an elastomer material, in particular gelatin, fine-granular foam, or silicone, and is thus at least partially elastically deformable. In the present case, the pressing head 20 is made entirely from the elastomer material. Alternatively, the pressing head 20 can, for example, also have a non-deformable core, made in particular from metal or hard plastic, which is encased in the elastomer material.In this respect, the pressing head 20 always has an elastically deformable pressing surface 21 on the outside, which can be assigned or is assigned to the film 8 or the surface 12. In the present case, the pressing surface 21 is convex in an initial state, but can also have a different surface geometry. As already mentioned above, the film 8 or the image transfer surface 4 is pressed against the printing surface 18 by means of the pressing device 16, in this case the pressing head 20, for transferring the printed image 5. As described in particular in this regard in . Figure 2CAs can be clearly seen, the pressure head or its pressure surface 21, with the film 8 interposed, continuously adapts to the printing surface 18 with continuous pressure, so that it is at least partially complementary to the printing surface 18. In this respect, the pressure head 20 or the elastically deformable pressure surface 21 adapts optimally to the surface geometry of the printing surface 18 during the pressing process. This advantageously ensures, particularly in conjunction with the flexible film 8, that the image transfer surface 4 is pressed precisely onto the printing surface 18, whereby the contact pressure 17 is evenly distributed over the printing surface 18 or acts on it. As a result, the print image 5 is transferred essentially without any loss of quality, and high-quality printing of the object 19 is ensured.In this case, the film 8 is subjected to the pressure 17 essentially in a point-like manner, i.e. starting from a starting point, in particular due to the convex design of the pressing surface 21 in the initial state, so that during the pressing process, distortions or folds of the film 8 and / or air inclusions between the image transfer surface 4 and the printing surface 18, which can negatively affect the quality of the printed image 5, are essentially avoided.

[0045] Figures 3A to 3D show the above-described process sequence using a second exemplary embodiment of the device 1. Identical elements are designated by the same reference numerals, referring to the above description. Therefore, only the differences will be explained in more detail below.

[0046] The second, in the Figures 3A to 3D The embodiment of the device 1 shown differs from the one previously described with reference to the Figures 2A to 2D The first embodiment described above is characterized in that the pressing device 16 is designed as a balloon 22 that is displaceable in the direction of the surface 12 and filled with a fluid, in particular compressed air or a liquid. The balloon 22 is elastically deformable or expandable and is preferably made of silicone or latex with a maximum wall thickness of 1 mm. Analogous to the pressing head 20, the balloon 22 is displaceable to the surface 12 by means of displacement means (not shown), as for example in Figure 3Bis shown. In the present case, the balloon 22 is closed and is therefore always filled with a constant amount of fluid. Alternatively, however, the balloon 22 can also have a valve by means of which it can be filled with the fluid or by means of which the fluid can be removed from the balloon. In this case, the device has a conveying device (not shown here), for example a pneumatic control, for conveying the fluid, wherein the displacement of the balloon 22 and / or the contact pressure 17 can be controlled in particular by the conveyed amount of fluid.

[0047] The procedure of the second embodiment is essentially identical to the first embodiment. As shown in particular in Figures 3B and 3CAs can be seen, due to the internal pressure caused by the fluid, the balloon 22, similar to the pressing head 20, conforms from a starting point with continuous pressure and with the interposition of the film 8 to the surface geometry of the printing surface 18, so that the printed image 5 is transferred to the printing surface 18 in an optimal manner and essentially without any air pockets between the image transfer surface 4 and the printing surface 18. The design of the pressing device 16 as a balloon 22 offers the advantage that it is an embodiment of the pressing device 16 that can be produced particularly cost-effectively. In addition, when the balloon 22 is designed as a balloon 22 that can be filled by means of the conveying device, the pressing pressure 17 can be easily adjusted by means of the quantity of fluid conveyed.

[0048] Figures 4A to 4Dshow the sequence of the method using a third embodiment of the device 1 not according to the invention. Identical elements are designated by the same reference numerals, which refer to the description above. Therefore, only the differences will be explained in more detail below.

[0049] The third, in the Figures 4A to 4DThe embodiment of the device 1 shown differs from the previous two embodiments in that the pressing device 16 is designed as a compressed air chamber 23 that can be filled with compressed air and is formed or delimited by the film 8. The compressed air chamber 23 has a base body 24 that is in the present case trough-shaped. At least two side walls 25 of the base body 24 each have a receptacle 26 designed as an opening, in which the holding frame 7 of the printed image intermediate carrier 6 is detachably fastened, preferably locked. In this respect, in the present third embodiment, the receptacles 26 form the bearing device 9, which in this case is formed integrally with the pressing device 16, in this case the compressed air chamber 23. As in particular in the Figure 4AAs can be seen in the cross-section of the device 1 shown, the intermediate printed image carrier 6 is inserted into the base body 24 in such a way that the film 8 seals off the open side of the trough-shaped base body 24. In this respect, the compressed air chamber 23 is formed by the film 8, which is placed sealingly on the base body 24 in the manner of a lid.

[0050] The compressed air chamber 23 or its base body 24 has an opening 28 in a bottom wall 27, which forms an inlet and outlet for the compressed air with which the compressed air chamber 23 can be filled. Preferably, a valve (not shown here) is arranged at or in the opening 28, for example, to prevent a pressure drop due to an uncontrolled outflow of the compressed air. To convey the compressed air into and out of the compressed air chamber 23, the device 1 has a conveying device (not shown here), which is fluidically connected to the opening 28 and serves to control the inflow and outflow of the compressed air and thereby adjust the contact pressure 17.

[0051] The process sequence in the present third embodiment is essentially identical to the two previous embodiments. In steps S2 and S3, as in, for example, Figures 4B and 4CAs shown, in order to generate the contact pressure 17 or to apply the contact pressure 17 to the film 8, the compressed air is conveyed through the opening 28 into the interior of the compressed air chamber 23. Due to the increased internal pressure of the compressed air chamber 23 compared to the ambient pressure, the flexible film 8, which also forms the compressed air chamber 23, bulges outwards and is thereby pressed with its image transfer surface 4 against the printing surface 18 in step S3, as in Figure 4C The compressed air chamber 23 offers the particular advantage that the contact pressure 17 is distributed particularly evenly across the surface 12, thereby particularly advantageously preventing the formation of wrinkles in the film 8 and / or air pockets. Furthermore, the contact pressure 17 can be controlled particularly precisely in this embodiment, thus enabling a particularly gentle transfer of the printed image 5 to the film 8 and / or the printing surface 18.

[0052] As an alternative to the foil 8 forming the compressed air chamber 23, it can also be provided in the third embodiment that the foil 8 only delimits the compressed air chamber 23. In this case, the base body 23 is designed to be closed, and instead of the previously mentioned open side, it has a flexible wall 29 which can be assigned to the foil 8 and which extends into the Figures 4A to 4Cis indicated by dashed lines. In this case, the film 8 is placed on the outside of the flexible wall 29. If the compressed air chamber 23 is filled with compressed air to apply the contact pressure 17 to the film 8 or its surface 12, the flexible wall 29 bulges outwards, whereby the applied film 8 also bulges accordingly. In this case, in step S3, the film 8 is therefore interposed between the flexible wall 29 exerting the contact pressure 17 and the pressure surface 18. However, since the film 8, as already mentioned several times above, is taut and therefore has a certain internal stress, the flexible wall 29 is limited in its bulge by the film 8. List of reference symbols

[0053] 1Device 2Print head, digital print head 3Image transfer element 4Image transfer surface 5Printed image 5'Ink 6Printed image intermediate carrier 7Holding frame 8Foil 9Bearing device 10Pivoting device 11First arrow 12Opposite surface 13Support element 14Second arrow 15Third arrow 16Pressing device 17Pressure pressure 18Printing surface 19Object 20Pressing head 21Pressing surface 22Balloon 23Compressed air chamber 24Main body 25Side walls 26Receptacle 27Bottom wall 28Opening 29Flexible wall

Claims

1. Method for printing on or decorating an object (19) which has at least one uneven, in particular convex or concave, printing face (18) on which at least one printed image (5) is printed, wherein, in order to print on the printing face (18), the printed image (5) is produced on an image transfer surface (4) of an image transfer element (3) by means of at least one digital print head (2) by a digital printing process and then the printed image (5) is transferred onto the printing face (18) by pressing the image transfer surface (4) onto the printing face (18), wherein an interchangeable printed image intermediate carrier (6) is used as the image transfer element (3), which carrier comprises a holding frame (7) and comprises a film (8), in particular an elastomer film, which is held flat, in particular pre-tensioned, in the holding frame (7), and has the image transfer surface (4), and wherein the image transfer surface (4) is pressed by means of at least one pressing device (16) which can be displaced, in particular is elastically deformable or can be filled with a fluid, in particular compressed air, wherein the pressing device (16) applies a preset pressing pressure (17) to a surface (12) of the film (8) opposite the image transfer surface (4) in order to press the image transfer surface (4) onto the printing face (18) and thereby transfer the printed image (5) from the image transfer surface (4) onto the printing face (5), characterized in that during the production of the printed image (5) on the image transfer surface (4), the film (5) is supported and thus pre-tensioned by a support element (13) which can be displaced in the direction of the surface (12) opposite the image transfer surface (4).

2. Method according to claim 1, characterized in that the printed image (5) is produced by means of an inkjet process.

3. Method according to any of the preceding claims, characterized in that, before the pressing, the printed image (5) is subjected to a radiation treatment to increase the viscosity of the printed image (5), and in that a highly pigmented ink (5') which can be cured in particular by means of LED, UV or infrared light is used for the printed image (5).

4. Method according to any of the preceding claims, characterized in that the printed image intermediate carrier (6) is pivoted by means of a pivoting device (10), in particular by 180°, before it is pressed on.

5. Method according to any of the preceding claims, characterized in that a stretchable and tear-resistant material, in particular silicone elastomer or silicone rubber or latex, is used as the film (8), in particular the elastomer film, wherein the film (8) is tensioned in the holding frame (7) at a Shore degree in a range of 2 to 20 Shore.

6. Method according to any of the preceding claims, characterized in that a pressing head (20) is used as the pressing device (16), which head is formed at least in part from an elastomer material, in particular gelatin or silicone, can be moved in the direction of the film and has an elastically deformable pressing face (21), which in particular is convex in an initial state.

7. Method according to any of claims 1 to 5, characterized in that a balloon (22) which can be filled or is filled with a fluid, in particular compressed air, is used as the pressing device (16).

8. Method according to any of claims 1 to 5, characterized in that a compressed air chamber (23) which can be filled with compressed air and is delimited or co-formed by the film (8) is used as the pressing device (16).

9. Method according to any of the preceding claims, characterized in that the printed image intermediate carrier (6) is movably and / or interchangeably mounted in a mounting device (9).

10. Device (1) for carrying out the method according to one or more of the preceding claims, namely for printing on or decorating an object (19), which device has at least one digital print head (2) and at least one image transfer element (3), wherein a printed image (5) can be produced on an image transfer surface (4) of the image transfer element (3) by means of the digital print head (2) and the printed image (5) produced on the image transfer surface (4) can be transferred onto an uneven, in particular convex or concave, printing face (18) of the object (19) by pressing the image transfer surface (4) onto the printing face (18), wherein an interchangeable printed image intermediate carrier (6) is provided as the image transfer element (3), which carrier comprises a holding frame (7) and comprises a film (8), in particular an elastomer film, which is held flat, in particular pre-tensioned, in the holding frame (7) and has the image transfer surface (4), and wherein, for the pressing of the image transfer surface (4), a pressing device (16) is provided which can be displaced, in particular is elastically deformable or can be filled with a fluid, in particular compressed air, wherein a preset pressing pressure (17) can be applied to a surface (12) of the film (8) opposite the image transfer surface (4) by the pressing device (16) in order to press the image transfer surface (4) onto the printing face (18) and thereby transfer the printed image (5) from the image transfer surface (4) onto the printing face (5), characterized in that the device (1) has a support element (13), which can be displaced in the direction of the film (8), for supporting and tensioning the film (8) during the production of the printed image (5) on the image transfer surface (4) of the film (5).

11. Device according to claim 10, characterized in that the pressing device (16) has a mounting device (9) for movably and / or interchangeably mounting the printed image intermediate carrier (6).

12. Device according to claim 11, characterized in that the apparatus (1) has a pivoting apparatus (10) for pivoting the film (8) before it is pressed against the printing face (18).