EP4301604A1

EP4301604A1 - Device and transfer printing procedure of an improved type

Info

Publication number: EP4301604A1
Application number: EP22705405.3A
Authority: EP
Inventors: Stefano SCALDAFERRO
Original assignee: Multi Griffe Srl; Stand Up Srl
Current assignee: Multi Griffe Srl; Stand Up Srl
Priority date: 2021-03-02
Filing date: 2022-02-16
Publication date: 2024-01-10
Anticipated expiration: 2042-02-16
Also published as: IT202100004850A1; EP4301604C0; WO2022184438A1; EP4301604B1

Abstract

The device and the process resulting of the idea of the Invention, consist in an integration of some layers of materials that operate in synergy when undergo the pressure, for example, of a heated printing elastic pad, allowing a "transfer" printing on a predetermined surface.

Description

Device and transfer printing procedure of an improved type

The Invention is revealed within those printing techniques developed to transfer graphic elements using the pressure of template and/or elastic pads and/or other similar elements heated on appropriate pigmented tapes. Putting pressure on the pigmented tape through the aforementioned elements, it releases the desired graphic elements on the surface object of the printing process. The aforementioned procedures are commonly defined as “transfer”.

The printing techniques by means of pigmented tapes, or “transfer”, are already known in the State of the Art. The tapes contain colouring elements, which when heated and placed in contact with adequate pressures on surfaces, allow the colours to be permanently imprinted, so realizing the printing process.

Obviously, not all the tape is heated but only that portion bounded by the surface of contact with the template and/or the elastic pad and/or other similar elements.

In particular, in Prior Arts are developed some templates in which in relief, likewise a cliché, are outlined the graphic characters to be printed. This layout means that only the relief of the template comes into contact with the pigmented tape, so only the same shape of the relief is permanently transferred on the surface object of the printing process.

Recent developments in the technical evolution of printing have made it possible to replace the template with an elastic pad, more suitable for adhering the pigmented tape to surfaces that are not perfectly planar, so characterized by an uneven or curved profile. In this case, however, the peculiar shape of the graphic character to be printed must already be present in its own entirety on the surface of the pigmented tape, because the soft, uniform and elastic profile of the pad would not allow any predetermination of a characteristic layout of the printing graphic element.

In consideration of the variety of the items on which it is possible to profitably apply the “transfer” printing processes, it is obvious that the use of the heated elastic pads allows a wider and more versatile range of use, as the templates can be effectively used on mostly flat and linear surfaces.

The use of heated elastic pads for the “transfer” technique brings the printing process closer to an already known technique called “pad printing”, in which the graphic element is transferred by the contact of the elastic pad to a cliché inked by an appropriate device. When the pad is put in contact with the item to be printed, the ink on its surface (ink collected by the cliché) is transferred to the printing area

Each of the two techniques in comparison, the one of “transfer” and the one of “pad printing”, has peculiarities that make them prefer alternately depending on the fields of application. The “transfer” techniques by pigmented tape allow a decrease of the parts constituting the printing machine; moreover, they allow a rationalization of the operational processes in order to increase the speed of execution and the industrial yield.

In the national application JPH11254718A, for example, it is possible to see a printing machinery from which can be deduced a use of the pigmented tape. A heated mechanic head (2) put the pigmented tape (7) in contact with the surface to be printed (10). In this application the presence of two rails of the pigmented tape integral with the movement of the thermal head (9-1) (9-2) allows an improvement of the printing process in relation to the constant working angle between the thermal head and the tape. The applications CN105243417A and US2011266349A1 reveal techniques for the realization of devices such as RFID tags and Smart Cards, which can be marginally traced back to the application processes of transfer elements using supports of the present application; however these patents concern specific product and non-technical process of graphic applications. Furthermore, the flexibility characteristics of the support in these applications are not suitable for transfer printing.

The limitations of the actual “transfer” technique concern the characteristics of the tapes on which the predetermined pigments or graphic elements for the printing are contained. To this day, the State of the Art does not allow the use of these technological solutions for printing on surfaces characterized by accentuated angles, or highly uneven profiles, which makes very difficult the use of the “transfer” technique on the majority of items available on the market.

Take for example a shoe on which you want to print a graphic element (20), graphic element extended from the outer perimeter edge of the aforementioned shoe up to the shoe upper, in the heel area. It is undeniable that the outer perimeter edge relief is characterized by an angle of 90° (21) in relation to the shoe upper (22) and that above-mentioned portion is unlikely coverable by a printing with a “transfer” or other technique.

Moreover, during a process of “transfer” type on a non-perfectly planar area, some unwanted movement of the same “transfer” can be produced on the same surface of the item to be printed, especially during the pressure contact procedure between the surface to be printed, the transfer and the template/pad.

To overcome this problem the purpose of the present Invention is to reveal an innovative “transfer” device provided with unique constructive characteristics that can go beyond the limits therein shown and allow a perfect printing quality even on those surfaces that are difficult to process, that is the non-planar ones and characterized by angles and marked deformations.

The purpose of the present Invention is, moreover, to define a perfected and peculiar printing process in such a way to add further characteristics to the item during the execution of the “transfer” printing, for the purpose of modify some physical and mechanical parameters of the printed surface.

The device and the process resulting of the idea of the Invention, consist in an integration of some layers of materials that operate in synergy when undergo the pressure, for example, of a heated printing elastic pad, allowing a “transfer” printing on a predetermined surface.

The abovementioned layers can be grouped together in support and functional layers, in order to contain the transfer element and to allow printing on non-planar surfaces, as well as adding additional functionalities; a layer in which is contained the real graphic element to be printed (the transfer element) and one or more protection layers, that grant the protection of the device. The totality of all layers forms the transfer sheet that is the subject of this Invention.

The main advantages of the idea resulting from the invention are listed below: 1) The device allows a safe application of the graphic elements of the transfer elements on non-planar surfaces and characterized by angles equal to or less than 90° and obviously in those greater than 90°; 2) the device is applicable by means of the use of a suitably heated elastic print pad, already available in the State of the Art of the technique, or other similar functional elements; 3) the device, during the application phase, has an elevated stability on the surface to be printed, avoiding incorrect or difficult placements, thanks to the adhesive layer prepared on it; 4) the device allows modifying the physical, chemical and mechanical characteristics of the materials’ surfaces object of the printing; 5) the device allows to include on the surfaces object of the transfer printing, active/passive communication devices and of sensor type or otherwise, in order to obtain additional functionalities.

The drawing table is integrated in the documents of this application in order to exemplify the characteristics of the Invention, even highlighting variations in the application described therein; in this case:

Fig.1

reveals the Prior Art JPH11254718A,

Fig.2

reveals a “transfer” printing on a shoe,

Fig.3

reveals the PU (Polyurethane) support sheet according to the idea of the Invention,

Fig.4

reveals the support sheet together with the lower protection layer, in paper or PET, according to the idea of the Invention,

Fig.5

reveals the glue layer on the support sheet according to the idea of the Invention,

Fig.6

reveals the transfer element deposited on the support sheet according to the idea of the Invention,

Fig.7

reveals the upper protection layer in silicone paper on the support sheet and on the transfer element according to the idea of the invention,

Fig.8

reveals the completed transfer sheet according to the idea of the Invention,

Fig.9

reveals a possible form of deposit of the additional glue layer on the transfer element according to the idea of the Invention,

Fig.10

reveals the presence of a TAG RFID element on the transfer element according to the idea of the Invention,

Fig.11

reveals the presence of a flexible circuital element on the transfer element according to the idea of the Invention,

Fig.12

reveals the removal phase of the upper silicone paper layer and the lower PET or paper one according to the idea of the invention,

Fig.13

reveals the application of the support sheet and of the transfer element on the surface of a shoe, according to the idea of the Invention

Fig.14

reveals the phase of cohesion of the transfer element, by means of pressure and temperature according to the idea of the Invention,

Fig.15

reveals the removal of the support sheet and of the transfer element integral with the shoe.

The description of the different forms of realization of this Invention is revealed here for illustrative purpose and it is not intended to be completely exhaustive or limited to the form of realization described therein.Moreover, all possible modifications of an obvious nature of the Invention and its scope put in place by persons experienced in the field do not limit the terms of protection of the license itself.

The length, time and pressure parameters in this Description comply with the International System of Unit of measurement (S.I.). In this document, the term “strato” is equivalent in meaning to the English term “layer”.

According to the embodiment of the Invention, the Device can be described as a multilayer sheet of individually and especially designed materials called “transfer sheet”, created for specific purposes in transfer printing processes.

The main support layer on which the transfer sheet is built is made up of a transparent sheet of PU (Polyurethane) (30), elastic and flexible, characterized by a typical thickness of 100um (100x10^-6 meters). This thickness can be suitably changed, for specific applications, respectively between the minimum and maximum values of 50 and 500 um. Moreover, it is possible to replace the Polyurethane with other similar synthetic substance, as long as it shows a pronounced resistance and stability to heat.

The peculiar thickness of the PU (Polyurethane) support sheet has been chosen in order to obtain the characteristics of flexibility and elasticity, necessary in this application, combined with the likewise necessary requisites of robustness.

According to the form of realization of the invention, this PU support sheet is coupled further down to a layer made up of a material such as paper or PET (Polyethylene terephthalate) (40). The purpose of this coating is to cover and protect further down the support sheet and make the transfer sheet, once completed, workable in the following phases of completion; moreover, the transfer sheet, so equipped, can be easily stored and applied in total safety.

According to the form of realization of the Invention, on the upper surface of the PU (Polyurethane) support layer, that is the one opposite to the paper or PET layer, an adhesive layer is realized (50). The purpose of this adhesive layer is to allow a highly stable placement on the surfaces to be printed. This solution, according to the idea of the Invention, is particularly advantageous because the surfaces to be treated by means of the “transfer” process can be non-planar and with interstices and angled outlines (20) in which the application and the stabilization of the transfer sheet before the printing process can be extremely complicated.

Moreover, the pressure applied, for example, by a heated elastic printing pad, can further contribute to modify the position of the transfer sheet, degrading the quality of the final printing.

According to the form of realization of the Invention, the construction of the adhesive layer must guarantee, in addition, a substantial tenacity of the glue itself to the PU (Polyurethane) support layer so that part of the glue does not migrate to the printed surface during the printing process. For this aim it is used a glue whose cross-linking takes place only through the exposure to UV rays (ultraviolet). For this aim it is also preferable the use of specific glues, for example that category of substances that totally lose their adhesive peculiarities after a thermal treatment. This choice can be advantageous because, after the printing process by pressure and temperature, the PU (Polyurethane) support sheet would be more easily removed from the transfer cohesive to the printed surface and without any deleterious mechanical action on the surfaces contiguous and adjacent to the one covered by the transfer itself.

According to the form of realization of the Invention, on the same adhesive layer the actual transfer element is then realized (60), that is the peculiar graphic element that you want to transfer through the printing process.

The realization of this graphic element can be carried out through techniques already known by the State of the Art as, for example, the silk-screen ones. So, through the utilization of a silk-screen chassis, the transfer steps of the synthetic and/or natural coloured materials are completed, until the completion of the realization of the transfer element.

The transfer element can contain in itself a pronounced adhesiveness when it is submitted to an application procedure by pressure and high temperature; however it is also possible to apply on the same, exactly in the area bounded by the surface of the transfer itself, additional and peculiar adhesive mixtures, which we will call “additional glues”, already known at the State of the Art. These adhesives can be of various chemical nature with various distinctive physical characteristics on the basis of the field of application in use.

The construction of the transfer element can also be carried out with further materials, techniques and/or processes already known to the State of the Art as, for example, the ones that use a plotter or the laser cut. In this case, all the further manufacturing are completed in order to obtain a perfect transfer element shape, removing all the parts that allow the building of the transfer but that must not, however, be held inside it (for example, waste and scraps of processing). The materials that can make up the transfer element are chosen according to the construction technique of the same and can obviously also vary according to the technical requirements that are required for the printing.

According to the form of realization of the Invention, the transfer element is protected by the insertion of a further security layer upon it (70). This layer can conveniently consist of a suitable material such as, for example, silicone paper, or similar, that allows to protect, moreover, the adhesive layer put on the whole PU (Polyurethane) support sheet from the contact with ashes and substances that could alter its chemical/physical integrity. The completion of the application of the protective layer coincides with the conclusion of the production process of the transfer sheet according to the idea of the Invention (80).

According to another form of realization of the Invention it is possible to provide for a different executive layout of the transfer sheet.This layout provides that the transfer element is put on the support layer without that the adhesive layer is previously deposited.

This alternative layout provides, at this point, to deposit an adhesive masking around the transfer, on the PU (Polyurethane) support sheet, such as to lend the aforementioned stability characteristics of the transfer sheet during its application on the surface to be printed.

According to another form of realization of the Invention it is possible to diversify the quality, the quantity and the distribution of the additional glue in the transfer graphic element depending on the materials on which the printing processes will be applied (90)(91). Taking ( ) as an example, it is clear that the material that makes up the outsole of the shoe can be synthetic while the material that makes the upper part (22) can be a natural one such as, for example, leather.

It is evident how a different distribution and composition of the additional glue on the transfer element can facilitate the correct anchoring of the element itself on the surface to be printed, so that to ensure a correct stability of the transfer element when the printing process is completed.

According to another form of realization of the Invention it is also possible to predispose the insertion of functional layers suitable to modify the physical characteristics of the surfaces object of the transfer printing. The transfer element can be conveniently supplemented by a layer of structural reinforcement material, such as carbon and/or graphene, or equipped with further characteristics such as waterproofing, UV resistance, peculiar germicidal properties etc. that offer additional features to the product thus printed (for example, features of structural reinforcement), features that go beyond the aesthetic needs typical of printing processes in general. What the device, resulting from the idea of the Invention, achieves is that the mechanical and physical characteristics of the transfer element are transferred on the printed surface, because perfectly integral with it.

According to another form of realization of the Invention a further evolution of this technique is the one that allows the application of passive/or active communication and control elements through the printing process by the utilization of the transfer sheet resulting from the idea of the Invention. In ( ) is visible a PU (Polyurethane) support layer on which, after a first partial print of the transfer element, a TAG RFID (Radio Frequency Identification) device is inserted (100). At this point, the process involves the completion of the transfer element realization such that the TAG RFID is incorporated into it. The printing of this transfer element on a chosen product will allow the application of this RFID element on it without any other production processes.

Obviously, the devices that can be integrated into the transfer element can be of various nature, for example specific sensors, photovoltaic cells, unique identification TAG, printed flexible microcircuits, devices for Black Chain control procedures etc. It is therefore possible to insert further functional layers in the transfer sheet, result of the present Invention, in order to support and/or to protect those additional elements so that their operation, once printed on the final product, is guaranteed for a sufficient period of time.

According to another form of realization of the Invention, it is also possible to add the aforementioned additional devices even when they are put outside the area of the transfer element, so when they are arranged on the area of the PU (Polyurethane) support sheet, as long as these devices are equipped with a typical adhesiveness when subjected to the thermal and pressure action of the elastic pad.

In ( ) is visible the application, by the transfer element, of a flexible, miniaturized electrical circuit (110), powered by a photovoltaic cell (111).

According to the procedure resulting from the idea of the invention, the completed transfer sheet is sent to the printing process, which will allow perfect bonding of the transfer element on the surface of the chosen item.

Printing procedure according to the idea of the Invention: the coating layer in silicone paper and the layer in paper/PET are removed from the transfer sheet (120)(121), result of the idea of the invention; the remaining PU (Polyurethane) support layer, that contains the transfer element, is then placed on the surface to be printed, making the transfer element adhere to it and exploiting the adhesive power of the glue of the support layer in PU (Polyurethane) to ensure that, once positioned, it is not subject to further movements during the processing phases. During the abovementioned procedure, it is possible to improve, manually or by machinery/tool fit to the purpose, the placement of the PU support that contains the transfer element on the surface to be printed. In this way, the transfer element remains perfectly adherent even to non-planar surfaces or surfaces with angles equal to or less than 90° (130).

Through the use of a tab heated to a prearranged temperature an adequate pressure is carried out on the support layer in PU (polyurethane), on the transfer element and on the surface object of the printing (140). In this case, the use of the pad can be replaced by any heated element that can be used for the purpose of this field of application.

Elapsed a reasonable time for the activation of the gluing of the transfer element, the elastic pad is moved away while the support layer in PU is definitely removed, making sure that the transfer element, glued to the surface object of the printing process, is the only element left glued to the same surface (150).

The procedure and the device result of the Invention can be used in various fields of application even if, obviously, the areas of choice are those of graphic processing on leather goods and textile materials in general, footwear, accessories, clothing etc.

The peculiar improvement introduced by the Invention, however, makes profitable the use of the device therein revealed also for the realization of “smart clothes”, or those clothes where there is a strong technological integration in order to innovate and enhance their peculiar intrinsic characteristics.

No Citation:

JPH11254718A

CN105243417A

US2011266349A1

Claims

Hot transfer printing device composed by a carrier film made of elastic and flexible PU (Polyurethane) material with an average thickness of 100 um (100x10-6m) variable from a minimum of 50 um to a maximum of 500 um (30) wherein: 1) a PU (Polyurethane) carrier film surface is covered with a paper or PET (Polyethylene terephthalate) protection layer, such as to completely cover the above surface (40); 2) the PU (Polyurethane) carrier film surface opposite to one covered by the protection layer in paper or PET (Polyethylene terephthalate) is covered in all its area by a glue layer able to crosslink when exposed to an electromagnetic radiation in the UV (Ultraviolet) band (50); 3) above the PU (Polyurethane) carrier film surface covered by the glue layer, a transfer element (60) is made by screen printing or other known printing technique, also with one or more structural reinforcement elements like carbon and/or graphene or other similar materials, also with germicidal substances, 4) the PU (Polyurethane) carrier film, the glue layer and the transfer element are all covered by a protection layer in silicone paper or other similar material (70).
Application procedure for hot transfer printing device of the Claim 1 wherein: 1) the paper or PET (Polyethylene terephthalate) protection layer and the silicone paper protection layer or other similar material one, are separated by the PU (Polyurethane) carrier film in which the transfer element is placed (120)(121); 2) the transfer element is made adhere to surface to be printed and is secured on it by the adhesive layer on the PU (Polyurethane) carrier film (130); 3) the PU (Polyurethane) carrier film and the transfer are subjected to a thermal and a pressure process (140); 4) the PU (Polyurethane) carrier film is separated by the transfer element (150).
Hot transfer printing device of the Claim 1 in which on the surface of the transfer element is made an additional adhesive layer.
Hot transfer printing device of the Claim 3 in which the distribution of the additional adhesive layer above the transfer element is not homogeneous.
Hot transfer printing device of the Claim 3 in which the type of the additional adhesive layer above the transfer element it consists of two or more chemical variants.
Hot transfer printing device of the Claim 1 in which the glue layer above the PU (Polyurethane) carrier film surface loses its adhesive features when subjected to heat treatment.
Hot transfer printing device of the Claim 1 in which the transfer element has inside one or more passive and / or active communication electronic devices.
Hot transfer printing device of the Claim 1 in which the transfer element has inside one or more substances for the UV (Ultraviolet) shield.
Hot transfer printing device of the Claim 1 in which the transfer element has inside one or more elements for the unique identification.
Hot transfer printing device of the Claims 7,8 and 9 in which the additional element made by passive or active devices, the structural reinforcements, the germicidal substances, the UV (Ultraviolet) shield and the elements for unique identification are equipped with own adhesive features and placed above the PU (Polyurethane) carrier film.