Method and apparatus for decorating objects with sublimation ink

Abstract

A method for decorating an object with sublimation ink, the method comprising the steps of: providing a shrink-wrapped sheet element (2), to which at least one layer of sublimation ink (3) is applied, and having an irregular surface (2a) on at least one face of the shrink-wrapped sheet element (2) designed to guide toward an object (4) to be decorated; joining two opposite ends of the sheet element (2) to obtain a sleeve (11), wherein the face of the sheet element (2) is guided toward the interior of the sleeve (11); axially inserting at least one object (4) to be decorated into the sleeve (11); applying heat to obtain at least a partial shrink wrap of the sleeve (11); creating a pressure difference between the inner and outer sides of the sleeve to establish a lower hydrostatic pressure on the inner side of the sleeve (11) than on its outer side; and applying heat to cause sublimation of the sublimation ink.

Description

Technical Field

[0001] This invention relates to a method and apparatus for decorating objects with sublimatic ink, which is particularly suitable for, but not necessarily suitable for, decorating hollow objects. Background Technology

[0002] A method known in the art as “sublimation transfer” is based on the transfer of an image provided by sublimation ink from a sheet-like medium called a carrier to the surface of an object to be decorated, called an imprintable material.

[0003] Specifically, this type of method is basically used to deposit sublimation ink on one side of a sheet medium, bring the ink side of the sheet medium into contact with the surface of the object to be decorated, and apply heat to achieve the sublimation of the ink and their subsequent transfer from the sheet medium to the object to be decorated.

[0004] Different ways of performing this type of currently known method determine different levels of quality and fidelity when transferring an image onto an object to be decorated.

[0005] For example, US5308426 describes a decorating method using a sheet-like medium made of a thermoelastic-plastic material. Besides being expensive, this method results in a loss of resolution in the transferred image if stretched or elongated, and tends to create wrinkles that cause defects in the transferred image if compressed. Furthermore, using the methods taught in this prior art document, it appears difficult to perfectly adjust the shape of the medium, making it difficult to transfer the image onto the object to be decorated.

[0006] US6814831 teaches a method that uses one or more frames to lock a circumferentially oriented carrier sheet medium made of an elasto-plastic material, which is deformed by adding heat and applying a pressure difference between its opposing surfaces until the sublimation temperature of the ink is reached. This prior art document also provides the possibility of thermoforming the carrier sheet medium in a first step and positioning it onto the object to be decorated in a second step by applying suitable pressure and temperature using elasto-plastic sheet devices and / or mechanical elements.

[0007] One drawback of this method is the inability to control the deformation of the carrier sheet medium, leading to instability in the contact between the carrier sheet medium and the object to be decorated, as well as significantly associated graphic inaccuracies. Furthermore, in addition to being quite laborious, this method requires the use of a large number of components and materials.

[0008] Another widely used method involves wrapping the object to be decorated with a carrier sheet medium, joining its two opposing flaps together in various ways, and inserting the object wrapped in the carrier sheet medium into a frame, such as those in the methods described above, or into a bag, thereby creating a vacuum through which process pressure can be transferred from the bag to the sheet medium wrapped around the object.

[0009] The disadvantages of this technique are the joints due to the use of different frames, and the fact that the bags, in addition to being never reusable, have a limit to plastic deformation, resulting in a lack of uniformity under applied pressure and, consequently, graphic defects in the transferred images.

[0010] It is also known to provide a method of using a shrink-wrapped sleeve on which an image to be transferred to an object to be decorated can be printed directly on its inner surface, or the shrink-wrapped sleeve can be used to allow an actual carrier sheet medium to adhere to the object to be decorated after it has shrunk.

[0011] This technique has limitations in the variability of the pressure applied locally to the object by the shrink-wrapped sleeve during the transfer of the image onto the object.

[0012] Furthermore, this technique does not allow for control of the gas that forms within the sleeve during image transfer and can cause expansion, resulting in a loss of close contact between the carrier and the receiving surface of the object, and reducing the fidelity of the obtained image.

[0013] EP0888905A2 teaches that, in order to decorate an object by sublimation transfer, a shrink-wrapped sleeve obtained from a film, having an ink-facing side facing the object to be decorated, can be used to provide a heat-sealed shell into which the object to be decorated is inserted, and optionally, air is evacuated from the interior of the heat-sealed shell before the heat transfer for decoration. If the teachings of EP0888905A2 are applied to objects with pronounced concave and convex surfaces, such as, for example, bottles and their bottoms, it is impossible to uniformly decorate all points of the object because, during the ink transfer step, it is impossible to extract the gas generated between the film and the object to be decorated, which causes this partial counter-pressure to disrupt the decoration on surfaces with pronounced concave and convex surfaces, using the method described in the patent. Furthermore, the technique described in this prior art document does not allow for the satisfactory decoration of surface areas of an object with concave and convex surfaces that cannot be reached by the shrink-wrapping of the sleeve alone.

[0014] Furthermore, all the known methods described above cannot provide completely satisfactory results for decorating objects with specific shapes, especially objects with drastic size variations, areas with obvious concave or convex surfaces, cavities accessible through openings, axially symmetrical geometries, etc. (such as, for example, furniture, vases, ornamental statues, glass containers (such as bottles commonly used for liquids or perfume bottles), or metal objects (such as jars or bottles), or objects made of ceramic materials).

[0015] Carrier sheet media are also known from EP1432590 and EP1910088, which have irregular surfaces provided by the application of granular elements or fibers on the surface designed to face the object to be decorated.

[0016] The use of this medium also indicates room for improvement. Summary of the Invention

[0017] The object of the present invention is to provide a method and apparatus for decorating objects with sublimation ink, which can improve the prior art in one or more of the above aspects.

[0018] Within this objective, the object of the present invention is to provide a method for decorating an object with sublimation ink, which can provide better results than the prior art in terms of the quality and fidelity of the image transferred onto the object to be decorated.

[0019] Another object of the present invention is to provide a method for decorating objects with sublimation ink, which can be easily provided with a small amount of simple operation and low cost.

[0020] Another object of the present invention is to provide a device for decorating objects that are easy to use and practical.

[0021] Another objective of this invention is to overcome the shortcomings of the prior art in a way that replaces any existing solutions.

[0022] The object of the present invention is not only to provide an apparatus that is highly reliable and readily available, thereby enabling its production at a competitive cost and using industrial methods.

[0023] This objective, as well as these and other objectives, can be achieved by means of the method for decorating objects with sublimation ink according to the invention, optionally having one or more features according to various embodiments of the invention. Attached Figure Description

[0024] Other features and advantages of the invention will become more apparent from the description of preferred, but not exclusive, embodiments of the method and apparatus according to the invention, which are illustrated by way of non-limiting example in the accompanying drawings, wherein:

[0025] Figure 1 This is a view of the object to be decorated and the steps of preparing the carrier sheet medium according to the present invention;

[0026] Figure 2 It is a view of inserting the object to be decorated into a sleeve provided by a carrier sheet medium;

[0027] Figure 3 This is a view of the connection of the device used to create a pressure difference between the inside and outside of the sleeve;

[0028] Figure 4 and Figure 5 This is a sequential view of the shrink wrapping of the sleeve performed in the furnace, which is schematically shown in side and sectional views;

[0029] Figure 6 This is a view showing the transfer of an image onto an object to be decorated, performed inside the furnace in cross-section, highlighting how the sleeve adheres perfectly to the concave bottom of the object due to the pressure difference applied during the thermo-elastic-plastic step.

[0030] Figure 7 This is a side view of the sleeve seal;

[0031] Figure 8 This is an enlarged sectional view of the sealed sleeve section;

[0032] Figure 9 It is an enlarged cross-sectional view of the surface of the object to be decorated, where the carrier sheet-like medium adheres and rests against it;

[0033] Figures 10 to 12 This is a schematic side view of a series of steps according to a second embodiment of the method of the present invention;

[0034] Figure 13 This is a cross-sectional side view of a vacuum packaging machine that can be used in a second embodiment of the method according to the invention during the process of vacuum packaging a bag of an object to be decorated into an insert sleeve;

[0035] Figure 14 This is a partially enlarged cross-sectional view of an object to be decorated according to a second embodiment of the method of the present invention, the object being inserted into a sleeve and packaged inside a vacuum bag;

[0036] Figure 15 It is a graph of the temperatures reached during the execution of the method according to the invention;

[0037] Figure 16 This is a flowchart of the steps of the method according to the present invention;

[0038] Figure 17This is a schematic diagram of the airflow generated in the sleeve due to the existing channel system. Detailed Implementation

[0039] Referring to the accompanying drawings, the method according to the invention for decorating an object with sublimation ink requires first providing a shrink-wrapped sheet element 2, on which at least one layer of sublimation ink 3 is applied.

[0040] Preferably, the sheet element 2 is of the type commonly used for decoration by sleeves, i.e., it is thermomechanically deformable in the radial direction of the sleeve, while its axial dimensions remain substantially constant.

[0041] The sheet element 2 has at least one irregular or rough drainage surface 2a on its first surface designed to face the object 4 to be decorated. This drainage surface 2a functions to form a channel system, more specifically a microchannel system, between the sheet element 2 and the object 4 to be decorated. This channel system is conveniently and uniformly disposed on the sheet element 2 and is advantageously constituted by a communicating cavity formed between the elements, where throttling occurs at the contact points between the surface of the sheet element 2 and the surface of the object 4 to be decorated. This channel system is adapted to allow complete exhaust of air and other gases inserted between the sheet element 2 and the object 4 to be decorated, thereby achieving optimal adhesion between the sheet element 2 and the object 4 to be decorated during the process of transferring sublimation ink.

[0042] Furthermore, as described below, since part of the process requires the removal of the existing volume of atmosphere between the sheet element 2 and the surface of the object to be decorated 4, the concave or convex gap component of the channel system branches on the entire surface of the sheet element 2, allowing the emptying and transmission of the minimum pressure level present in the system, thereby overcoming the effects that would occur if the sheet element 2 and the object to be decorated 4 were not present.

[0043] More specifically, such as Figure 9 Of particular note, the sheet element 2 is provided by a base film 5 made of shrink-packed polymer material and at least one working layer 6 having an irregular surface 2a.

[0044] In particular, the thickness of the base film 5 is preferably substantially between 5 μm and 150 μm, more preferably between 35 μm and 70 μm, and is capable of automatically reducing at least one of its own dimensions between 5% and 95% of the initial size, more preferably between 60% and 85%, as a result of increased heat as the temperature increases within the range of 50°C to 200°C, more preferably between 60°C and 90°C.

[0045] For example, the base film 5 can be made of PET, PVC, PLA, OPS or other materials, and can be easily extruded, stretched and cooled to have the typical thermo-elastic-plastic mechanical properties of shrink-wrap sleeves.

[0046] Conveniently, if the base film 5 does not have sufficient impermeability to the vapor-phase sublimation ink, a continuously applied impermeable layer (not shown) can be applied to its surface facing the working layer 6. This impermeable layer functions to prevent the vapor-phase sublimation ink from diffusing toward the base film 5. For example, this impermeable layer can be made of polyvinyl alcohol with a high hydrolysis value.

[0047] The working layer 6 is advantageously composed of an absorbent and an adhesive layer 7, preferably made of PVOH, wherein an omnidirectional isotropic channel system is present, which allows each individual point of close contact between the film and the object to be decorated 4 to be connected by microchannels, which allow the discharge of sublimation gases and corresponding solvents generated during the transfer step of the sublimation ink.

[0048] These channel systems are obtained by applying a body 8 of granular and / or rectangular shape to layer 7, with dimensions substantially between 1 μm and 300 μm, preferably between 5 μm and 100 μm, having a suitable uniform distribution on the working layer with an appropriate distribution density and an isotropic geometric arrangement with a non-preferred orientation, allowing the provision of surface 2a such that the working layer 6 has a granular and channel shape suitable for the geometric complexity of the object 4 to be decorated.

[0049] It should be noted that the non-preferred orientation of the channel system is necessary to avoid the formation of channels with such flow capacity that they become the preferred path for gases formed during the sublimation transfer step, thus deforming the membrane during their outflow, making decoration along the channels themselves impossible, or contaminating the object to be decorated near the channels. This results in a significant sublimation gas flow relative to the remaining area of ​​the object.

[0050] Specifically, the density, shape, and size of the body 8 are selected based on the ink material used, the expected graphic resolution, and the difficulty depending on the shape of the object 4 to be decorated. The integrity of the channel system, and therefore the structure of the body 8 and the permeability of the cavities inserted between them, must be maintained throughout all steps of the process, and therefore they must withstand the thermal and mechanical stresses transmitted by the sheet elements 2 on which they are arranged due to some of the potential (or residual) shear strength. For example, when flow difficulties exist due to the shape of the object 4 to be decorated, this is addressed by altering the size and concentration of the body 8 and the thermomechanical properties of the carrier blades (i.e., the sheet elements 2).

[0051] The particles and / or rectangular bodies 8 preferably have thermomechanical properties such that they substantially maintain their geometric dimensions and thus their function of guiding aeraulic flow remains unchanged during the transfer step, i.e., during the application of pressures and temperatures suitable for the process.

[0052] For example, the granular body 8 can be made of granular silicates or organic materials, while the rectangular body 8 can be made of synthetic fibers or other suitable materials.

[0053] For example, when using an ink material in which the solvent used for application has been largely evacuated, a channel system that requires the removal of the gas phase has a body 8 with a substantially smaller cross-section, such as 7 μm, compared to a water-based ink material that requires a drainage channel system with a body 8 having a much larger cross-section, because there is a larger volume of gas to be evacuated, such as a size close to 20 μm.

[0054] Similarly, if the object 4 to be decorated has a particularly obvious concave surface and corners, it is necessary to use a body 8 with a larger diameter, even if the chemical-physical structure of the ink material and the working layer remains constant, in order to ensure the minimum cross-section of the channel system. Otherwise, the tensile stress of the ink medium on the surface of the object 4 will block the channel system.

[0055] Conveniently, a substance capable of absorbing sublimation ink and its solvent is present in the adhesive layer 7 to ensure a certain degree of tactile dryness once the layer of sublimation ink 3 is applied. For example, this substance may be a diol family substance and / or anthraquinone family substance.

[0056] These absorbent materials allow for direct printing of media elements using digital, rotary gravure, flexographic, and other printing technologies.

[0057] It should be noted, in particular, such as Figure 9 As shown, the sublimation ink 3 layer can be applied over the channel surface 2a, or alternatively, it can be placed between the base film 5 and the working layer 6. In the latter case, the adhesive layer 7 is made of an adhesive material that is at least partially permeable to gas, and more precisely, of an adhesive material that is at least partially permeable to the gas phase of the sublimation ink, such as, for example, conventional ethyl cellulose or synthetic adhesive materials.

[0058] Advantageously, depending on the size and shape of the object 4 to be decorated, sheet-like elements 2 can be obtained by cutting continuous strips 10, which preferably have a higher shrink wrap along their transverse extension direction than along their longitudinal extension direction.

[0059] In addition, strip 10 may have a layer of sublimation ink 3 applied before cutting.

[0060] The sheet element 2 can conveniently have a main extension in the longitudinal direction so as to have a generally rectangular shape in the plan view, thereby forming a pair of long sides and a pair of short sides in practice.

[0061] It should be noted that in the area to be cut, the working layer 6 may be optionally missing from the band 10, and in that area it consists only of the base film 5.

[0062] Once the sheet element 2 is prepared, its two opposite ends are joined together to form a sleeve 11, which is open at its opposite axial ends and can accommodate the object 4 to be decorated inside.

[0063] Specifically, the sleeve 11 is provided by arranging the surface of the sheet element 2, on which the ink surface 2a is provided, such that the surface points toward the inside of the sleeve.

[0064] For example, the connection between the two ends of the sheet element 2 is achieved by overlapping and heat-sealing the two corresponding flaps of the sheet element 2, preferably by inserting a solvent material, such as dioxolane (CAS646-06-0), between them, especially when the base film 5 of the sheet element providing the sleeve 11 is made of PET. This ensures effective airtightness between the inside and outside of the sleeve 11 at the joint line 11a of the two flaps.

[0065] It should be noted that the area of ​​the sheet element 2 corresponding to the overlapping fins held on the outside of the sleeve 11 advantageously lacks the working layer 6.

[0066] At this point, one continues to insert at least one object 4 to be decorated axially into the sleeve 11. For example, the object 4 to be decorated may be a bottle, as shown in the figure.

[0067] Thus, the sleeve 11 is arranged around the object 4 to be decorated, covering the exterior of the object 4, and its position relative to the object 4 depends on the position where one wishes to transfer the image onto the object.

[0068] Preferably, but not necessarily, the sleeve 11 is provided with an axial length greater than the axial dimension of the object 4 to be decorated, so that it protrudes relative to the axial end of the object 4 once the object 4 to be decorated is inserted into the sleeve 11.

[0069] For this purpose, the sleeve 11 can be provided from a generally rectangular sheet element 2, the long side of which is longer than the axial length of the object 4 to be decorated, and by connecting the ends of the sheet element 2 corresponding to its long side to each other, the sleeve 11 can have an axial extension greater than the axial extension of the object 4 to be decorated once obtained.

[0070] It should be noted that before the object 4 to be decorated is inserted into the sleeve 11, the object 4 may also undergo surface treatment to adapt it for optimal reception of the diffusion of sublimation gases. For example, such treatment may include applying an organic coating based on epoxy resin, acrylic resin, polyester, polyurethane, or combinations thereof in liquid form, based on solvents, water, and / or powders, using a spray dispenser, electrostatic spraying, fluidized bed, or other means. These products, applied at a convenient thickness, are cured by cycles of heating or irradiation upon exposure to a suitable heat / UV source to achieve the desired consistency in thickness designed to receive the sublimation ink.

[0071] In this respect, heat is applied to the sleeve 11 by exposing it to a suitable heat source, thereby raising the temperature of the sleeve 11 above the temperature at which the sheet element 2 shrinks and wraps, so that the sleeve 11 partially shrinks and wraps on the object 4 to be decorated, thereby obtaining an envelope that facilitates contact with the object 4, and optimizing the positioning of the decorative pattern on the surface of the object 4. This ensures that each point finds its coplanar projection on the object 4 to be decorated.

[0072] Specifically, the shrink wrapping of the sleeve 11 results in a narrowing of the lateral dimension of the sleeve 11, so that at least a portion of the sleeve 11 adheres to and abuts against at least a portion of the object 4 to be decorated, thereby at least partially adapting it to the shape of the outer surface of the object 4 to be decorated, thus providing a convenient enclosing surface.

[0073] Preferably, the shrink wrapping of the sleeve 11 is provided by exposing the sleeve 11 to at least one heat source to rapidly and uniformly reach the shrinkage temperature of most of the surface of the sleeve.

[0074] Therefore, sleeve 11 can be conveniently exposed to a heat radiation source, with a surface temperature between 80°C and 700°C for a time that is essentially between 0.1s and 45s.

[0075] It should be noted that if a suitable protective coating, such as a wax-based UV coating with hydrophobic properties, is applied to the inside of the sleeve 11, superheated steam can be used as the heat source for the shrink wrap of the sleeve 11.

[0076] For example, such as Figure 4 and Figure 5As illustrated, the shrink wrapping of the sleeve 11 can be performed by placing the sleeve 11 into which the object 4 to be decorated is inserted into a shrink wrapping furnace 12, which is preferably of a static type and conveniently has a well-like structure and is provided with a radiation plate 13 capable of emitting infrared (IR) radiation inside.

[0077] Once the shrink wrapping is complete and the object has been allowed to cool, the shrink-wrapped sleeve 11 can have various different areas depending on the shape and size of the object 4 to be decorated.

[0078] Specifically, refer to Figure 7 and Figure 11 The sleeve 11 may have at least one first region 11a located at the portion of the object 4 to be decorated having the largest lateral dimension, wherein the shrink-wrapped sleeve 11 adheres to the outer surface of the object 4 to be decorated with contact pressure that depends on the shrinkage percentage of the sheet element 2 and the curvature degree of the object 4 to be decorated.

[0079] It should be noted that although the pressure of the shrink-wrapped sleeve 11 against the object 4 to be decorated exists in the first region 11a, it is not usually uniform.

[0080] As shown in the figure, if the object 4 to be decorated is a bottle, then in fact, the first region 11a is the region of the shrink-wrapped sleeve 11 located at the body of the bottle.

[0081] The shrink wrap sleeve 11 may also have at least one second region 11b, wherein the contact between the shrink wrap sleeve 11 and the object 4 to be decorated is only partial, although the shrink wrap conveniently brings the sheet element 2 closer to the surface of the object 4 to be decorated. Image transfer is not possible in this region 11b. If the object 4 to be decorated is a bottle, then this second region 11b actually corresponds to the region of the shrink wrap sleeve 11 located at the neck of the bottle.

[0082] Advantageously, the shrink-wrapped sleeve 11 also has two additional regions, namely a third region 11c and a fourth region 11d, respectively corresponding to the ends of the shrink-wrapped sleeve 11, which protrudes beyond the axial ends of the object 4 to be decorated before shrink-wrapping. In these regions 11c and 11d, the sleeve 11 is shrunken to its maximum percentage, although the contact pressure on the object 4 to be decorated is insufficient to achieve the close contact and pressure required for transferring sublimation ink.

[0083] Once the shrink wrapping of the sleeve 11 on the object 4 to be decorated has been performed, the method proceeds to the subsequent step, described in more detail below, which involves creating a pressure difference between the inner and outer sides of the shrink-wrapped sleeve 11 on the object 4 to be decorated, so as to determine a lower hydrostatic pressure on the inner side of the sleeve than the hydrostatic pressure acting on its outer side. That is, a partial vacuum is created inside the sleeve 11 relative to the external environment.

[0084] Preferably, before or simultaneously with the step of creating a pressure difference between the inner and outer sides of the shrink-wrapped sleeve 11 on the object to be decorated, there is a step of changing the state of the sleeve 11 by applying at least sufficient heat energy to the sleeve 11 to reach and maintain the temperature of the sleeve 11 at about 70°C to 90°C, preferably 80°C. That is, a temperature corresponding to the plastic phase transition or glass transition temperature of the sleeve, so as to achieve a uniform pressure distribution on the inner side of the sleeve 11. In this way, uniform compression of the sleeve 11 against the object to be decorated is subsequently obtained through the channel system present on the surface 2a of the sheet element 2 providing the sleeve 11.

[0085] The channel system described above is particularly important for the successful diffusion of partial vacuum, or, under positive pressure, for its uniformity across the entire surface of the object-sleeve closure, and to avoid the "suction cup" effect of the sleeve on the object surface, which would prevent the vacuum from diffusing in concave areas of the object, or, under positive pressure, would create bubbles that would damage the decoration.

[0086] Before or during the step of creating a partial vacuum inside the sleeve 11, heat is applied to the sleeve 11 to transform it into a plastic state, for example, to a temperature of about 80°C or higher than the glass transition temperature of the sleeve 11, thereby allowing optimal deformation of the sleeve 11 and the corresponding surface to which it is joined with the object 4 to be decorated. Because of the plastic phase reaching the sheet element 2, deterioration and breakage due to the primary elastic-rigid properties, which would occur at ambient temperature or in any case at a temperature not close to the glass transition temperature, are avoided, resulting in a loss of seal and thus a loss of partial vacuum inside the sleeve 11. Simultaneously, in the thermal zone prior to the start of sublimation pattern transfer, the placement of the decoration obtained during the previous shrink-wrapping step can be defined.

[0087] In other words, the temperature interval between the glass transition step and the sublimation temperature of the sheet element is advantageously utilized to maintain the placement of the envelope obtained in the shrink wrapping step. If the application of the pressure differential occurs in a more advanced thermal stage, the thermo-elastoplastic properties of the sheet element 2 (which tend to lose its shape at high temperatures and yield under stress) will cause a change in the shape of the envelope surface of the sheet element 2, resulting in the loss of the placement of the decoration (typically with tight tolerances) obtained during the shrink wrapping step, which would therefore be inconvenient for optimal and reliable pattern transfer.

[0088] In this regard, additionally, preferably at a temperature of up to about 150°C to 200°C, heat is applied to the shrink-wrapped sleeve 11 on the object 4 to be decorated, preferably having undergone a plastic phase transition temperature of about 80°C, and also subjected to a pressure difference between its inner and outer sides in order to cause the sublimation of the ink, so that the sublimation ink is transferred to the surface of the object 4 to be decorated.

[0089] The method ends with removing the decorative object from sleeve 11.

[0090] Figure 15 A graph illustrating the temperature trends of the sleeve 11 and the object to be decorated during various steps of the method according to the invention is shown by way of example, wherein t a t represents ambient temperature. s The temperature at which the ink sublimates, t. g Indicates the glass transition temperature of sleeve 11, and i p This indicates the temperature range of the plastic phase in sleeve 11.

[0091] Figure 15 The steps of the method shown are also Figure 16 The flowchart schematically illustrates that: I designates a first step, which includes placing the object 4 to be decorated (such as a bottle) on the process line; II represents a second step, which includes heating the bottle to substantially equal temperature t. g The temperature; III indicates the third step, which includes applying sleeve 11 to a preheated bottle at ambient temperature; IV indicates the fourth step, which includes applying heat to the shrink wrap of sleeve 11; V indicates the fifth step, which includes sealing the package of the bottle provided by sleeve 11; VI specifies the sixth step of optional storage, which subsequently acclimates the package to the storage temperature; VII indicates the seventh step, which includes heat-sealing the package connected to the pressure vessel to reach the plastic phase of sleeve 11 (t>t). gVIII represents the eighth step, which includes heating the package while applying a pressure difference between the sleeve 11 and thus between the inside and outside of the package; IX represents the ninth step, which includes further heating the package while applying a pressure difference to cause sublimation transfer of the ink; X represents the tenth step, which includes cooling the package and continuing the sublimation transfer of the ink until exhausted; and XI represents the eleventh step, which includes removing the sleeve 11 from the bottle and then ending the processing cycle.

[0092] According to a first embodiment of the method of the present invention, such as Figures 1 to 9 As shown in the example, the stage of creating a pressure difference between the inside and outside of the sleeve 11 is performed by drawing air from the inside of the sleeve 11.

[0093] In this case, such as Figure 3 As shown, before performing shrink wrapping on sleeve 11, the inlet end of at least one suction channel 14 is inserted into sleeve 11 through at least one end of sleeve 11.

[0094] Specifically, the portion of the suction tube 14 inserted into the sleeve 11 is sufficient to ensure that at least a portion of the suction tube 14 remains within the shrink-wrapped sleeve 11 even after the sleeve 11 has been shrunk.

[0095] The suction pipe 14 is adapted to be connected, for example, via a connecting connector 15 to an air suction line 16, which includes, for example, a vacuum pump 17 and a valve 18 optionally for opening or closing the connection between the suction pipe 14 and the vacuum pump 17.

[0096] It should be noted that the connection between the suction pipe 14 and the suction line 16 can also be provided after the shrink wrap of the sleeve 11 is performed.

[0097] Optionally, if the object 4 to be decorated is a bottle, the suction tube 14 can be inserted into the mouth of the bottle.

[0098] like Figure 4 and Figure 5 As shown, in order to shrink the packaging sleeve 11, in this case, the sleeve 11 and part of the suction pipe 14 are inserted into the shrink packaging furnace 12, wherein the object 4 to be decorated is inside the shrink packaging furnace 12.

[0099] Advantageously, after the sleeve 11 is shrunkenly wrapped on the object 4 to be decorated and the suction pipe 14, a seal is performed on the axial end of the sleeve 11 to ensure airtightness between the inner and outer sides of the sleeve at its end.

[0100] Specifically, at the end of the sleeve 11, a suction tube 14 is inserted therein. In the example of the accompanying drawings, the suction tube 14 is formed by a fourth region 11d of the shrink-wrapped sleeve 11, by forming an airtight seal between the outer surfaces of the sleeve 11 and the suction tube 14, for example by an annular element 19 placed around the sleeve 11 and provided, for example, by a wound tape, a type that is conveniently able to withstand high temperatures, or by a shrink tape, or by a suitable mechanical connector.

[0101] At the other end of the sleeve 11, i.e., referring to the example in the accompanying drawings, in the third region 11c of the shrink-wrapped sleeve 11, the end opening of the sleeve 11 is also sealed by a mechanical clamp, for example by means of... Figure 7 The fixture 20 shown is provided by heat sealing or ultrasonic welding, or by using tape or a cap or other similar element, thereby advantageously ensuring that it is used for substantially equal to about 10 -3 The pressure of the bar is airtight.

[0102] Once this seal at the end of sleeve 11 is complete, the connection between suction pipe 14 and vacuum pump 17 can be initiated to allow air to be drawn from inside sleeve 11.

[0103] Once the glass transition temperature of the sleeve 11 has been reached and maintained simultaneously with the applied heat, air is drawn from the inside of the sleeve 11 to cause the ink to sublimate.

[0104] For this purpose, the shrink-wrapped and sealed sleeve 11 is advantageously inserted into the hot air ventilation furnace 21, which is capable of heat exchange through radiation and hot air circulation.

[0105] Conveniently, the furnace 21 includes a housing 22, which internally forms a heating chamber 23 adapted to accommodate the object to be decorated and at least a portion of the suction pipe 14, the object to be decorated being inserted into the sleeve 11.

[0106] The heating chamber 23 is at least partially defined by a heat dissipation device, which is conveniently composed of a heat dissipation plate 24.

[0107] The furnace 21 is also provided with a device for forced air circulation, which consists, for example, at least one fan 25, preferably arranged on the upper side of the heating chamber 23, which can be activated on command to generate an airflow in the heating chamber 23, the airflow preferably being guided along the main axis of the object to be decorated.

[0108] Inside the outer shell 22 of the furnace 21, along the air circulation channel 26 defined outside the heating chamber 23, preferably between the outer shell 22 and the heat sink 24, there is at least one resistance heater 27, which can be supplied with electrical energy to heat the airflow generated by the fan 25.

[0109] In addition, the heating chamber 23 has a support grid for the sleeve 11, in which the object 4 to be decorated is inside the sleeve 11 so as to allow airflow generated by the fan 25 to pass through.

[0110] Advantageously, the furnace 21 is also provided with means for communication between the interior of the sleeve 11 and the air extraction device, which, in the case shown, is constituted, for example, by at least one opening 29 formed in the heating chamber 23 through which a suction pipe 14 can pass, so as to allow the suction pipe 14 to be connected to an air suction line 16, which is conveniently located outside the housing 22 and conveniently connected to the suction pipe 14 via a connector 15.

[0111] Once the sleeve 11 with the object to be decorated 4 inserted therein and the suction pipe 14 have been inserted into the furnace 21 and the suction pipe 14 has been connected to the air suction line 16 (and more specifically to the vacuum pump 17), the furnace 21 can be started to impinge the sleeve 11 with a flow of hot air having a velocity, for example, between 4 m / s and 60 m / s and a temperature, for example, between 80°C and 250°C, and the vacuum pump 17 is started to generate a negative pressure in the sleeve 11, i.e., a pressure below ambient pressure, for example, between 700 mbar and 999 mbar, preferably between 980 mbar and 990 mbar.

[0112] It should be noted that the airflow generated and impacting the sleeve 11 in the furnace 21 makes it possible to apply a positive pressure, i.e., a pressure greater than the ambient pressure, to the outside of the sleeve 11. This helps to create a pressure difference between the inside and outside of the sleeve, so that the sleeve 11 can abut against the outer surface of the object 4 to be decorated.

[0113] It should be noted that under certain hydrodynamic conditions that can be readily obtained by controlling the airflow inside the furnace 21, the connection between the inner side of the sleeve 11 and the suction line 16 may become redundant, as the pressure applied to the outer side of the sleeve 11 by the airflow is sufficient to achieve the required compression of the sleeve 11 against the outer surface of the object 4 to be decorated.

[0114] During the process of holding the sleeve 11, into which the object 4 to be decorated is inserted, in the furnace 21, and during the application of the vacuum generated in the sleeve 11 by the vacuum pump 17 through the suction pipe 14, a gas phase flow is obtained from the inside of the sleeve 11 toward its outside. This gas phase flow includes any air present in the object 4 to be decorated. If the object is made of a bottle, this includes the air present in the gap 30 between the sheet element 2 providing the sleeve 11 and the outer surface of the object 4 to be decorated, as well as the gas generated under the pressure and temperature conditions generated inside the sleeve 11.

[0115] More specifically, through the channel system formed by the irregular surface 2a of the sheet element 2, and the communication between the gap 30 between the sleeve 11 and the object to be decorated 4 and the suction pipe 14, a pressure lower than the pressure applied by air to the outside of the sleeve 11 can be obtained between the sleeve 11 and the object to be decorated 4. As the compression of the sleeve 11 against the object to be decorated 4 increases accordingly, and the extraction of the gas phase generated in the gap 30, back pressure that could cause the sleeve 11 to expand and thus result in the transfer of sublimated ink to the object to be decorated 4 is prevented.

[0116] Furthermore, after prolonged exposure to a heat source, the sheet element 2 loses its shrink-wrapping properties and gradually exhibits elastoplastic behavior, while maintaining its properties of being essentially impermeable to gas in the thickness direction.

[0117] The primary thermoelastic-plastic behavior exhibited by the sheet element 2, combined with the pressure difference generated between the inner and outer sides of the sleeve 11, allows the sheet element 2 to further adapt to the surface of the object 4 to be decorated, so as to achieve certainty of contact between the sleeve 11 and the object 4 to be decorated.

[0118] In addition, it should be noted that the greater the pressure difference used to compress the sleeve 11 against the object 4 to be decorated, the more suitable the ink area of ​​the sheet element 2 is for the outer surface of the object 4 to be decorated.

[0119] It should also be considered that sublimation inks are composed of various substances that have different degrees of volatility relative to the local temperature and pressure.

[0120] Therefore, as the temperature of the sleeve 11 in the furnace 21 increases and the partial vacuum level inside it increases due to the air suction performed by the vacuum pump 17, the gradually generated unwanted gas phase that may interfere with the transfer of sublimation ink to the object 4 to be decorated is extracted from the sleeve 11.

[0121] In this way, the useful gas phases generated at temperatures and pressures close to the final method of the method, namely the gas phases of those sublimated inks, will find that the surface of the object 4 to be decorated is directly facing the layer of sublimated ink 3 when they are generated, and is therefore ready to receive them by diffusion, thereby providing decoration for the object 4.

[0122] Different embodiments of the method according to the present invention, such as Figures 10 to 14 As shown, a pressure difference can also be provided between the inside and outside of the sleeve 11 by wrapping the object 4 to be decorated 4 in the sleeve 11 into a bag 31 that creates a vacuum.

[0123] Advantageously, bag 31 is of the heat-sealable type and has an irregular surface defining a channel system, at least on its inner side, unlike those described above.

[0124] Conveniently, the bag 31 can be provided by one or more sheet elements having a structure similar to or substantially the same as that of sheet element 2, through which the sleeve 11 is provided.

[0125] It should be noted that, in order to obtain good results using this second embodiment, at least one empty hollow can suitable for use as a vacuum can must be provided inside the bag 31. In the case of bottle decoration, the bottle itself serves as the vacuum can. Alternatively, an alternative can, such as a hollow sphere or a cup-like element, can be inserted. The presence of the can is essential because, in the absence of a pump with a constant connection as in the first embodiment, which maintains a partial vacuum throughout the transfer phase, a can is needed in this second case to absorb the positive pressure generated during gas-phase sublimation. Again, in order to connect the can to the entire contact surface between the sheet element 2 and the object to be decorated 4, the channel system of the sheet element 2 of the bag 31 is essential for the proper balance of the internal local vacuum, thereby ensuring that the generated gas is delivered toward the can at a lower pressure. In fact, without such a channel system on the sheet element 2 and therefore on the bag 31, gas accumulation will occur and thus increase the local partial pressure, which will overcome the pressure exerted by the sheet element during the transfer step, and will ruin the decoration result, and will not allow the uniform diffusion of the local vacuum generated during processing.

[0126] Specifically, in this second embodiment, similar to the description above regarding the first embodiment, the sheet element 2 is initially arranged together with a layer of sublimation ink 3 applied thereto, and the two ends of the sheet element 2 are connected to provide a sleeve 11, into which the object 4 to be decorated is axially inserted, such as... Figure 10 As shown.

[0127] As in the first embodiment, in this case, at this point, as Figure 11 As illustrated, at least part of the sleeve 11 is shrunken and wrapped on the object 4 to be decorated by applying heat.

[0128] For example, in this case, shrink wrapping of sleeve 11 can also be provided by introducing sleeve 11 into shrink wrapping oven 12 into which the object 4 to be decorated is inserted, so that the temperature of sleeve 11 is substantially between 70°C and 90°C, for example, by exposing it to a heat radiation source with a temperature substantially between 80°C and 700°C for a time between 0.1 seconds and 45 seconds.

[0129] Once the shrink wrapping of sleeve 11 has been performed, the shrink-wrapped sleeve 11 with the object 4 to be decorated inserted therein is removed from the shrink wrapping oven 12, and preferably, after being cooled, it is placed in bag 31, such as Figure 12 As shown.

[0130] At this time, as Figure 13 As shown, a vacuum is created in bag 31, and then bag 31 is sealed.

[0131] For example, such as Figure 13 As shown, a bell-shaped vacuum packaging machine 32 is used to generate a vacuum and seal the bag 31. This vacuum packaging machine 32 has a vacuum chamber 33, which is accessible through an openable cover 34 and connected to a vacuum pump 35. The vacuum pump 35 generates, for example, approximately 10 ppm in the vacuum chamber 33. -3 The vacuum level of the bar became possible.

[0132] Vacuum chamber 33 is also connected to ambient air intake valve 36, which allows the ambient pressure in vacuum chamber 33 to be restored once the machine's operating cycle is completed.

[0133] Conveniently, there is also a pair of rods 37 inside the vacuum chamber 33 for sealing the bag 31, which are made of suitable resistance heaters.

[0134] In practice, using the vacuum packaging machine 32, after the bag 31 is introduced into the vacuum chamber 33 and the cover 34 is closed, the vacuum pump 35 is started until the desired vacuum is achieved in the vacuum chamber 33 and thus in the bag 31; then, the bag 31 is vacuum sealed near its inlet, and then atmospheric air is reintroduced into the vacuum chamber 33 through the opening of the air inlet valve 36, so that the cover 34 can be reopened and the vacuum-packed bag 31 inside, along with the sleeve 11 and the object 4 to be decorated inserted into the sleeve 11, can be removed.

[0135] In this respect, the vacuum-packed bag 31 inside, along with the sleeve 11 and the object 4 to be decorated, is heated by applying heat (preferably in the furnace 21) to reach the sublimation temperature of the sublimation ink, and then the ink is transferred to the object 4 to be decorated.

[0136] During the ink transfer step, the channel system inside the sheet element 2 of the sleeve 11 and the bag 31 allows the formed gas phase to flow toward the vacuum tank, thereby ensuring the uniformity of the contact pressure of the sheet element 2 on the object to be decorated.

[0137] Figure 17 The gradually increasing partial pressure p of the sublimation gas generated during the sublimation transfer of ink is illustrated schematically in part of sleeve 11 by way of example. I p II p III p IV p V p VI The possible distribution of isobars and corresponding flow vectors within the channel system of the sheet element 2.

[0138] After sufficient time for complete sublimation of the ink, the bag 31 is removed from the furnace 21 and then opened to remove the sleeve 11 containing the decorative object 4 inside.

[0139] At this point, all that remains is to remove sleeve 11 in order to free up decorative object 4.

[0140] In practice, it has been found that the present invention achieves the intended goals and objectives, providing a method that allows for the optimal transfer of sublimation inks even on objects with complex shapes.

[0141] The invention thus conceived is open to many modifications and variations, all of which are within the scope of the appended claims; furthermore, all details may be replaced by other technically equivalent elements.

[0142] In fact, the materials used, as long as they are suited to the specific purpose and have arbitrary shapes and sizes, can be any materials according to requirements and existing technology.

[0143] This application claims priority to the disclosure of Italian Patent Application No. 102020000015289, which is incorporated herein by reference.

[0144] Where any technical feature mentioned in a claim is followed by reference numerals, these reference numerals are included to increase the comprehensibility of the claim, and therefore these reference numerals have no limiting effect on the interpretation of each element identified by these reference numerals by way of example.

Claims

1. A method for decorating objects with sublimation ink, characterized in that, The method includes the following steps: providing a shrink-wrapped sheet element (2), to which at least one layer of sublimation ink (3) is applied, and an irregular surface (2a) is provided on at least one first surface of the shrink-wrapped sheet element (2) designed to guide toward the object (4) to be decorated; engaging two opposite ends of the sheet element (2) to obtain a sleeve (11), wherein the first surface of the sheet element (2) is guided toward the interior of the sleeve (11); axially inserting at least one object (4) to be decorated into the sleeve (11); applying heat to obtain at least a partial shrink-wrapping of the sleeve (11) so that at least a portion of the sleeve (11) adheres to at least a portion of the object (4) to be decorated; creating a pressure difference between the inner and outer sides of the sleeve so that a lower hydrostatic pressure is established on the inner side of the sleeve (11) than on its outer side; and applying heat to cause the sublimation of the sublimation ink.

2. The method of claim 1, wherein, The sleeve (11) has an axial extension larger than the object (4) to be decorated, the sleeve (11) protruding relative to the axial end of the object (4) to be decorated, wherein the object (4) to be decorated is inserted into the sleeve (11).

3. The method of claim 1, wherein, Before or during the step of generating the pressure difference, the method includes the step of transforming the sleeve (11) into a plastic state.

4. The method according to claim 1, characterized in that, The pressure difference is generated by drawing air from the inside of the sleeve (11).

5. The method of claim 1, wherein, Prior to the shrink wrapping, the method provides an inlet end of at least one suction pipe (14) inserted through at least one end of the sleeve (11) for suctioning air from inside the sleeve (11).

6. The method of claim 1, wherein, Following the shrink wrapping, the method provides a seal on the axial end of the sleeve (11) to create an airtight seal between the inner and outer sides of the sleeve (11).

7. The method of claim 5, wherein, After sealing, the method includes initiating the connection of the suction pipe (14) to the vacuum pump (17).

8. The method of claim 1, wherein, The pressure difference is generated by applying a positive pressure to the outside of the sleeve (11).

9. The method of claim 1, wherein, The pressure difference is generated by the sleeve (11) in the bag (31) under vacuum, wherein the object (4) to be decorated is inserted into the sleeve (11).

10. The method of claim 9, wherein, The bag (31) has an irregular surface at least on its inner side.

11. The method of claim 9, wherein, The method provides a vacuum chamber inside the bag (31).

12. The method of claim 1, wherein, Simultaneously, air is drawn from the inside of the sleeve (11) and heat is applied so that the sublimation ink sublimates in the ventilation oven (21).

13. The method of claim 1, wherein, The sheet element (2) can be directly printed with sublimation ink by a printing method selected from the group consisting of digital printing, rotary gravure printing and flexographic printing.

14. A device for decorating objects with sublimated ink according to the method of any of the preceding claims, characterized in that, The device includes: Suction pipe (14); A static type shrink wrapping oven (12) has a well-like structure and includes inside a radiation plate (13) capable of emitting infrared radiation for shrink wrapping sleeves (11) that extend beyond the length of the object (4) around the object (4) and partially around the suction pipe (14). A clamp (20) is used to seal one end opening leading to the sleeve (11); An air suction line (16) includes a vacuum pump (17) and is configured to connect to a suction pipe (14); and Another furnace (21) is provided with an outer shell, the outer shell forming an internal heating chamber (23) suitable for accommodating at least one object (4) to be decorated, the object (4) being inserted into a shrink sleeve (11) provided in a sheet element (2) coated with at least one layer of sublimation ink (3) and the suction pipe, the heating chamber (23) being at least partially defined by a thermal radiation device. The furnace (21) is equipped with a device for forced air circulation, which can be activated upon command to generate an airflow inside the heating chamber (23). The furnace (21) is also provided with an opening (29) formed in the heating chamber (23) for communication between the inside of the sleeve (11) and the vacuum pump (17), and can be passed through by the suction pipe (14) to allow the suction pipe (14) to be connected to an air suction line (16) outside the housing (22) and conveniently connected to the suction pipe (14) by a connector (15).

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