ITMO20110018A1 - DEVICE FOR HOT PRINTING, PARTICULARLY FOR REFRACTORY AND / OR RIGID MATERIALS. - Google Patents

Description

"DEVICE FOR HOT PRINTING, ESPECIALLY FOR REFRACTORY AND / OR RIGID MATERIALS".

DESCRIPTION

The present invention relates to a hot stamping device, particularly for refractory and / or rigid materials.

For several years and in the various commodity sectors, attention to the care of the packaging of commodity products has been continuously growing. The presentation to the consumer of a specific product with its own packaging distinguishable from other products, in addition to influencing the choice of the consumer himself, allows the consumer to identify the desired product among a myriad of similar items displayed in the same area.

The design of the product packaging is now recognized as one of the fundamental elements of the product itself, in particular the accent is increasingly placed on the decorations of the external surface of the packaging.

Particularly interesting is the decoration of the packaging of products for pharmaceuticals, cosmetics, beverages and the like, where the product is displayed inside a bottle or container made of plastic or glass and ceramic.

In the first case, i.e. in the case of decorations on plastic materials, the decoration takes place through a heated rigid pad that adheres to the plastic surface to be decorated, placing the decoration to be transferred between the pad and the surface to be decorated. In the second case, that is, in the case of decorations on glass or ceramic and more generally on refractory and / or rigid materials, it is not possible to use the same technique, as there are mainly two problems: the glass has a surface on which an adhesive for decorations it does not guarantee a constant and lasting adhesion over time and, secondly, the use of a rigid pad does not guarantee a perfect adhesion of the decoration to the surface.

In fact, the glass has an irregular surface due to small natural imperfections of the glass itself, on which a rigid surface is difficult to adhere perfectly.

The first solution, commonly used, to overcome the problems related to the adhesion of decorations on glass, consists in a pre-processing of the glass surface performed by screen printing machines that transfer on the surface to be decorated a layer of special ink that reproduces the desired decoration. and reacts thermally with an adhesive layer of the decoration to be applied. After the screen printing process, the object to be decorated is loaded into a second machine in which the final decoration is made by means of a multilayer film called "decorative foil".

The machines used to create this solution are mainly of three types which are briefly summarized below:

- "hot punch" device;

- "heated membrane" device;

- "rotary punch" device.

The "hot punch" device comprises a punch made of metallic material, generally aluminum, with a contact surface covered with an elastically deformable material, such as for example silicone. The punch is heated until it reaches about 190 ° and then placed on the object to be decorated at high pressure (the operating pressures can reach a few hundred bars).

A multilayer decorative film is interposed between the punch and the object to be decorated, mainly composed of a first layer of thermo-reactive adhesive that adheres to the object, a second plastic layer to support the decoration and finally a last decorative layer.

The combination of pressure and temperature allows the reaction of the special ink with the first layer of the film, for a perfect adhesion. Furthermore, the silicone layer, present on the punch, allows to compensate for all the natural imperfections present on the glass surface, adapting to the surface itself.

In this first type of device, the coating of elastically deformable material of the punch and the punch itself deteriorate quickly. The cost of replacing the punch is very onerous, since the punch is specifically produced according to characteristics defined by the surface to be decorated and the final decoration together for the production of a single type of product.

In the second type of device, called "heated membrane", the previous silicone-coated punch is replaced with an unheated silicone pad and a heated silicone membrane. The decoration process, similar to the previous one, involves heating by contact in a special seat of the membrane which, cyclically, is interposed between the pressing pad and between the multilayer decorative film and the object to be decorated.

The transfer of the decoration takes place when the pad applies a pressure by pressing the underlying elements that is, in sequence, the membrane, the decorative film and the object to be decorated, where the membrane guarantees the predetermined temperature for the thermal adhesion reaction.

In this second type of device the only element subject to wear is the membrane, whose replacement cost is much lower than the complete replacement of the punch, as in the first device, but at the same time the continuous thermal shocks to which it is subject to the membrane, between the subsequent heating and cooling, they reduce the life time of the membrane itself, requiring frequent maintenance and consequent numerous machine stops for the replacement of the membrane, reducing the production capacity of the device.

Furthermore, the cycle time of the machine, which defines the productivity of the machine, is defined by the heating and transfer of the membrane from the place where it is heated to the place where the decoration takes place, given that the time taken for the transfer of the decoration is shorter heating and membrane transfer times.

The third type of device, called "rotary punch", is able in part to solve the drawbacks previously described in relation to the first two types of previous devices, since this device uses a wheel with a surface entirely covered with elastically deformable and heat-conducting material.

This wheel, in continuous rotation, has a first sector subjected to heating by means of heating elements, such as infrared lamps, and a subsequent sector in which the wheel, at still high temperature, compresses the multilayer film against the object to be decorated.

This solution allows to obtain reduced cycle times and considerably lower operating pressures compared to previous devices.

Such known devices are not free from drawbacks, including the fact that the heating of the surface placed in contact with the decorative element does not guarantee a uniform and constant distribution of heat. This difference could make some parts of the decoration adhere perfectly, leaving others detached where the heated surface has a lower temperature than that required, consequently increasing production waste.

Another drawback encountered in the devices currently in use lies in the dimensions of the devices themselves. In fact, hot decoration devices require a structure of considerable size due to the presence of hydraulic mechanisms to develop high pressures and, in some cases, suitable seats for the cyclical heating of parts of the machinery itself.

These dimensions prevent inserting the device for the final decoration process directly in series with known type of silk-screen printing machines, always requiring the manual movement or by means of special manipulators of the object to be decorated from one machine to the next.

The main aim of the present invention is to eliminate the aforementioned drawbacks, by proposing a device for hot stamping, particularly for refractory and / or rigid materials, which reduces production waste ensuring homogeneous adhesion of the decoration on the object to be to decorate.

Within this aim, an object of the invention is to provide a hot stamping device which can be inserted in series with known types of glass screen printing machines.

Another object of the present invention is to provide a hot stamping device which has a simple structure, relatively easy to implement in practice, safe in use and effective in operation, as well as relatively low cost.

This task, as well as these and other purposes which will appear better below, are achieved by a hot stamping device, particularly for refractory and / or rigid materials, comprising a bearing structure to which at least one pressing element is associated which is movable along a first direction of translation from a rest position to a position of use with an object to be decorated, between said pressing element and said object to be decorated being interposable in contact, on the side of said object to be decorated, decorative means that can be transferred by heat and, on the side of said pressing element, a layer of elastically deformable polymeric material, characterized in that said layer comprises heat generating means suitable for heating said heat transferable decorative means.

Further characteristics and advantages will become clearer from the description of two preferred but not exclusive embodiments of the device according to the invention, illustrated by way of non-limiting example, in the accompanying drawings in which:

Figure 1 is a schematic front elevation view of a first embodiment of a hot stamping device, particularly for refractory and / or rigid materials, according to the invention, in its rest position;

figure 2 is a schematic front elevation view of the device shown in figure 1 in its position of use;

Figure 3 is a schematic front elevation view of a second embodiment of a hot stamping device, particularly for refractory and / or rigid materials, according to the invention, in its position of use;

Figure 4 is a section on an enlarged scale of the elastically deformable polymeric layer of the devices shown in the previous figures.

With particular reference to these figures, the device according to the invention, generally indicated in the two proposed embodiments with the reference numbers la and 1b, comprises a supporting structure 2 to which at least one pressing element 4 is associated, which it moves at least along a first direction of translation 3, which, in these particular embodiments, is substantially perpendicular to the support plane of the supporting structure 2.

More specifically, the pressing element 4, sliding along said first translation direction 3, passes from a rest position to a position of use. In the position of use, the pressing element 4 applies pressure to an object to be decorated 6 through two interposed elements, that is to say, decorative means 5 which can be transferred by heat and a layer 7 of elastically deformable polymeric material.

In particular, this layer 7 is in direct contact with the pressing element 4 and the decorative means 5 are in direct contact with the object to be decorated 6.

According to the invention, the layer 7, whose thickness is variable according to the construction and application requirements, comprises heat generating means 10 aimed at heating the heat transferable decorative means 5 to be applied on the object to be decorated 6.

More specifically, the layer 7 comprises a membrane 8 which is substantially sheet-like and made of an elastic heat-conducting material which, in these particular embodiments, is silicone.

Inside said membrane 8 there are the heat generating means 10 which are, specifically, defined by a metal fabric 11 which, by means of two power supply heads 9 associated with two end portions 13 of the metal fabric 11, is crossed by electric current. In particular, the metallic fabric 11 comprises a mesh of electroconductive wires 12 with opposite ends 13.

The mesh of electroconductive wires 12 can be made up of copper wires or other electroconductive material, in these particular embodiments the mesh of electroconductive wires 12 is made up of steel wires, a material that offers good mechanical resistance to the stresses to which the metallic fabric 11 is subjected during the decoration cycle.

Furthermore, the membrane 8 is in continuous mechanical tension thanks to retaining means 14 which retain it through the two end sections 13.

Through the holding means 14, the electric current is also supplied to the membrane 8 by means of electrical power supply terminals.

The power supply circuit comprises regulating means, not shown in the aforementioned figures, and temperature sensing means 26 which, operatively connected to the regulating means, allow to detect the temperature on the surface of the membrane 8 and consequently to regulate the current to obtain a constant preset temperature.

As regards the pressing means 4, which apply pressure directly on the membrane 8, these comprise a support element 16 and a contact head 15.

The contact head 15 is properly associated rotatably, in an idle way, to the support element 16. In particular, the contact head 15 is a substantially cylindrical roller 28 with a circular base with a rotation axis 21 substantially transverse to the first. direction of translation 3. The roller 28 has variable dimensions according to the surface to be decorated and is made of a material resistant to the temperature of the membrane 8.

The decorative element 5, in direct contact with the membrane 8, is advantageously positioned on a multilayer film 22, commonly called "decorative foil". The multilayer film 22 mainly comprises three layers of which, in sequence, a first layer of heat-reactive adhesive which, in the position of use is in contact with the object to be decorated 6, a second plastic support layer which acts as a base for the third colored layer that defines the final decoration, this third layer in the position of use is in direct contact with the membrane 8.

Like the membrane 8, the multilayer film 22 is also held in mechanical tension by winding means 18.

More specifically, the winding means 18 comprise a first reel 23, from which the multilayer film 22 with the decorative element 5 intact is unrolled, a second reel 24, in which the multilayer film 22 is rolled into which the decorative element 5 is absent due to its transfer to the object to be decorated 6, and from tensioning elements, known to the person skilled in the art and therefore not described in detail, between the first reel 23 and the second reel 24 to facilitate the sliding and tensioning of the multilayer film 22.

Finally, the devices la and 1b comprise support means 17, associated with the supporting structure 2, suitable for supporting the object to be decorated 6.

In the first embodiment la, illustrated in Figures 1 and 2, the pressing element 4 and therefore the roller 28, after reaching the end of the stroke of the first translation direction 3, i.e. in the position of use, is movable along a second direction translation 19.

This second translation direction 19 is substantially transverse to the first translation direction 3 and parallel to the membrane 8. Furthermore, in this embodiment, the support means 17 are firmly associated with the supporting structure 2 and comprise clamping elements for holding of the object to be decorated 6.

This embodiment is recommended for decoration on substantially planar surfaces.

In the second embodiment 1b, illustrated in Figure 3, the retaining means 14, in addition to keeping the membrane 8 under mechanical tension, are slidingly associated with the supporting structure 2 along a third translation direction 20 substantially transverse to the first translation direction 3 .

Furthermore, in this embodiment, the support means 17 are rotatably associated with the support structure.

More particularly, they comprise clamping elements for retaining the object to be decorated 6 which can rotate around an axis of rotation substantially parallel to the axis of rotation 21 of the roller 28.

This embodiment of the device 1b is advisable for transferring decorations on substantially elliptical or cylindrical surfaces.

The use of the devices 1a and 1b according to the invention is as follows.

The power supply means for the electric circuit feed the two ends 9 of the membrane 8 through the power supply terminals included in the retaining means 14.

Consequently, the mesh of electroconducting wires 12 offers a natural resistance to the passage of current due to the reduced section of the wires themselves; this resistance heats the wires according to the Joule effect, in fact the mesh of electroconducting wires 12 is composed of wires with a section sized in such a way as to have a resistance so as to obtain the pre-set temperature necessary for the operation of the devices la and lb.

The metallic fabric 11 heats up and transfers its heat to the outer surface of the membrane 8 through the silicone layer 7.

On this layer 7, present on both opposite surfaces of the membrane 8, the actual temperature is detected by means of the temperature detecting means 26.

More specifically, the temperature detecting means 26 can be of the optical type, of the resistive type or of another type aimed at detecting the temperature.

In these particular embodiments, the temperature detecting means 26 comprise sensors of the optical type.

The temperature reading is then sent, as information, to the adjustment means which, according to the data received in feedback, modulate the current to increase, decrease or leave unchanged the surface temperature of the membrane 8.

The temperature regulation must be very precise in order to guarantee the suitable temperature for the transfer of the decorative element.

In particular, the acceptable range of variation of the devices la and lb is a few degrees centigrade, quantifiable in 4-5 degrees centigrade.

Furthermore, the temperature of the membrane 8 is constantly kept under control even in the intermediate phases between one decoration phase and the next. The continuous regulation also compensates for environmental temperature variations due to both temporary temperature changes and seasonal cyclical temperature variations.

Once the surface temperature of the membrane 8 has been defined, compatibly with the reaction temperature required by the multilayer film 22, in order to make the decoration adhere to the object to be decorated, one proceeds with the mechanical action of pressure.

In particular, the pressing element 4 moves along the first direction of translation 3 by simultaneously pressing the membrane 8 and the multilayer film 22 against the object to be decorated 6.

The combination of temperature and pressure cause the first heat-reactive adhesive layer of the multilayer film 22 to react and the layer of silk-screened ink on the object to be decorated 6, allowing the adhesion of the decorative element 5 exclusively on the surface sections previously treated with the ink. screen printed previously.

In particular, the continuous monitoring of the temperature makes it possible to obtain a membrane 8 at a constant temperature throughout the decoration process, also compensating for drastic variations in the speed of the cycle.

Prior to the mechanical pressure action step, the object to be decorated 6 undergoes a screen printing process, known to the skilled in the art, in order to prepare the surface of the object to be decorated 6 for the thermal reaction with the adhesive of the multilayer film. 22.

Subsequently, after a first decoration, the decorated object is replaced with a new object to be decorated 6, positioning it on the support means 17. The multilayer film 22 is renewed by sliding it from the first reel 23 to the second reel 24, always keeping it in mechanical tension and in this way the device can cyclically decorate more objects.

Maintaining mechanical tension both of the membrane 8 and of the multilayer film 22 is essential for the decoration process, in order to guarantee uniform adhesion of the decoration, avoiding involuntary curling of the multilayer film 22 or of the membrane 8 during the decoration process.

It is also noted that the roller 28 substantially applies a pressure line on the surface to be decorated, allowing the use of pneumatic handling actuators with reduced dimensions, requiring operating pressures much lower than traditional devices, more specifically only a few bars of pressure.

In fact, in most of the known devices, pressure is applied simultaneously on the entire surface to be decorated and there is a high probability that some air particles remain trapped between the multilayer film 22 and the surface of the object to be decorated 6. To make high pressure must be applied to drain the trapped air particles outwards.

In the illustrated invention, the contact surface is substantially distributed along a line, where air particles can hardly remain trapped and the subsequent pressure applied along a line towards the end of the decoration helps to allow any air particles to flow outwards. This operation therefore does not require high operating pressures, being limited to a few bars.

Consequently, the moving members require actuators of reduced dimensions. This reduction in size allows the device to be housed in limited spaces, such as in series with existing screen printing machines, or in free work stations in screen printing machines, using the manipulator that moves the screen-printed piece to be decorated, further reducing time. cycle.

In particular, in the first embodiment the pressing element 4 translates along the first direction of translation 3 so as to be able to indirectly apply a pressure on the surface of the object to be decorated 6 in the position of use. In particular, the pressing element 4, through the roller 28, is in direct contact with the membrane 8 which, in turn, presses the multilayer film 22 which, consequently, presses the surface of the object to be decorated 6.

Subsequently, the pressing element 4 translates along the second translation direction 19, ensuring continuous pressure on the object to be decorated 6, making the roller 28 rotate freely on the membrane 8.

In the second embodiment, the pressing element 4 translates exclusively along the first translation direction 3, indirectly applying pressure on the surface of the object to be decorated 6, as illustrated in the first embodiment. More specifically, in the device 1b the holding means 14 translate the membrane 8 along the third translation direction 20.

In particular, the support means 17, rotatably associated with the supporting structure 2, rotate in synchrony with the translation of the membrane 8, ensuring that the peripheral speed of the surface of the object to be decorated 6 is equal to the translation speed of the membrane 8.

Since the roller 28 and the support means 17 are rotatably associated around two rotation axes parallel to each other, the translation of the membrane 8 and of the multilayer film 22 under pressure between the roller 28 and the object to be decorated 6, allows the roller 28 to apply a continuous line of pressure on the surface of the object to be decorated 6.

Advantageously, the holding means 14 translate along the third direction of translation 20 for a useful distance in order to make the decorative element 5 adhere completely to the object to be decorated 6.

More specifically, the multilayer film 22 follows the movement of the membrane 8, winding on the second reel 24 after a first decoration process, presenting a new area of the multilayer film 22 with a new decorative element 5 to be transferred onto another object to be decorated 6.

In practice it has been found that the hot stamping device, particularly for refractory and / or rigid materials, according to the invention fully achieves the intended aim as it allows to reduce production waste, ensuring a constant and homogeneous temperature throughout the decoration process, thus avoiding that different parts of the decoration do not adhere perfectly to the surface to be decorated.

A further advantage of the hot stamping device according to the invention is that it can be installed in series with screen printing machines, molding machines or even in workstations of existing screen printing machines, thanks to its small size.

Another advantage of the hot stamping device according to the invention is that of having increased the production capacity with respect to the known art, reducing the cycle time required for the decoration, since the heating of the membrane is independent of the speed of the device.

A further advantage of the hot stamping device according to the invention is that of having reduced production costs, in fact the membrane with heat generating means has a much longer life time than the membranes heated by contact, as it is not subjected to continuous shocks. thermal cooling and heating; it follows that the replacement of the diaphragm is required less frequently and the maintenance costs and downtime for the replacement of the same are drastically reduced.

The device for hot stamping, particularly for refractory and / or rigid materials, thus conceived, is susceptible of numerous modifications and variations, all of which are within the scope of the inventive concept.

Furthermore, all the details can be replaced by other technically equivalent elements.

In practice, the materials employed, so long as compatible with the specific use, as well as the contingent shapes and dimensions, may be any according to requirements without thereby abandoning the scope of protection of the following claims.

Claims (10)

CLAIMS 1) Device (la, lb) for hot stamping, particularly for refractory and / or rigid materials, comprising a bearing structure (2) to which is associated at least one pressing element (4) movable along a first direction of translation (3 ) from a rest position to a position of use with an object to be decorated (6), between said pressing element (4) and said object to be decorated (6), being interposable in contact, on the side of said object to be decorated (6) ), heat transferable decorative means (5) and, on the side of said pressing element (4), a layer (7) of elastically deformable polymeric material, characterized in that said layer (7) comprises heat generating means (10) suitable for heating said heat transferable decorative means (5). 2) Device (la, 1b) according to claim 1, characterized in that said layer (7) comprises a membrane (8) substantially sheet-like and made of an elastic heat-conducting material. 3) Device (la, 1b) according to claims 1 and 2, characterized in that said heat generating means (10) comprise a metal fabric (11) incorporated in said membrane (8), said metal fabric (11) comprising two end sections (13) associated with two power supply ends (9). 4) Device (la, 1b) according to one or more of the preceding claims, characterized in that said metal fabric (11) comprises a mesh of electroconductive wires (12) whose opposite ends (13) are connected to said ends (9) power supply. 5) Device (la, 1b) according to one or more of the preceding claims, characterized in that it comprises retaining means (14) for said membrane (8) suitable for maintaining the mechanical tension of said membrane (8). 6) Device (la, 1b) according to one or more of the preceding claims, characterized in that it comprises current regulating means and temperature sensing means (26) operatively connected to each other and to said electrical supply heads (9) suitable for regulating of the current circulating in said wire mesh (12) as a function of the surface temperature of said membrane (8) detected by said temperature sensing means (26). 7) Device (la, 1b) according to one or more of the preceding claims, characterized in that said pressing element (4) comprises a support element (16) and a contact head (15) of substantially cylindrical shape with a circular base and rotatably associated idly to said support element (16) around an axis of rotation (21) substantially transverse to said first direction of translation (3). 8) Device (la, 1b) according to one or more of the preceding claims, characterized in that said supporting structure (2) comprises support means (17) for said object to be decorated (6) and winding means (18) for said decorative element (5) suitable for maintaining in mechanical tension of said decorative element (5), said decorative element (5) being made from a multilayer film (22). 9) Device (la) according to one or more of the preceding claims, characterized in that said roller (28) is movable along a second translation direction (19) substantially transverse to said first translation direction (3) and substantially parallel to said membrane (8). 10) Device (1b) according to one or more of claims 1 to 8, characterized in that said support means (17) of said element to be decorated (6) are rotatably associated to said supporting structure (2) with rotation axis substantially parallel to the axis of rotation (21) of said roller (28) and said holding means (14) are slidingly associated with said bearing structure (2) along a third direction of translation (20) substantially transverse to said first direction ( 3).