DE9115738U1 - Device for laminating layers, identification cards, etc. - Google Patents

Description

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Tiroler Str. 15 D-7250 Leonberg Tel.07152/45421

2508/ot/wi
28.4.1992

Company Interlock AG., Rütistr. 16, CH-8 952 Schlieren

Device for laminating layers, identification cards, etc.

State of the art

The invention is based on a device for laminating layers of at least partially thermoplastic films according to the preamble of claim 1.

In a known method for laminating layers and a corresponding pressing device with two plates for carrying out the method (European patent application 0013557), the layers are pressed into a composite by the action of heat and pressure, whereby on each side of the surface formed by the layers

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The blank placed in the press is first heated by two plates, i.e. heat and pressure are applied on both sides and the heating effect is then switched off so that after cooling down, an identification card produced in this way can be removed from the press.

In addition to the arrangement of resistance wires in double-sided press plates of larger dimensions, which come into direct active connection with the layers to be laminated and which are shielded from the actual support plates of the press device to which they are attached via interposed insulating layers, it is also known from this publication to design the press plates as cooled support plates and to connect a flat heating resistance layer in front of them as a heating element, whereby the heating resistance layer faces directly towards the layers to be laminated and is thermally shielded from the cooled support plates by an insulating layer. Pulsed voltages are applied to the heating resistance layer from a heating voltage source, whereby a special feature of this known laminating device should also be mentioned, which is that certain heat-sensitive security features such as guilloche prints or watermarks, microfilm images, holograms and the like can be introduced into the produced check, ID or passport cards by arranging recessed stamps exclusively in the area of these additional pressure and temperature-sensitive security features, the temperature of which is lower than the temperature of the plates ensuring the laminating effect. Therefore, in the case of

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In the area of the stamp openings the pressure is lower than the lamination pressure, and the temperature is also lower than the temperature of the plate.

The problem with all known laminating devices is that the production cycle is divided into two easily distinguishable sub-cycles, namely the initial, as sudden as possible introduction of heat so that the laminating temperature of the layers of the identification card to be bonded together, as it will be referred to below, is reached, and a subsequent cooling cycle, which is initiated by switching off the heating elements, but during which it is not possible to open the pressing device and remove the welded card blank, as this does not yet have enough mechanical stability.

It is therefore desirable to first subject the blank in the press device or initially the inserted layer composite to a heating phase and then a cooling phase, whereby the insulating layer located between the flat foil heating layer and the press plate, which is usually still expressly cooled, has to fulfil two contradictory tasks, which it does equally poorly, namely, during the heating phase, to keep the amount of heat emitted or applied by the heating element away from the adjacent cooling plates as completely as possible and to direct it to the layers to be laminated and, on the other hand, during the cooling phase after the heating is switched off, to enable the previously suppressed heat flow as quickly and comprehensively as possible, and precisely

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in the direction towards the cooled support plates, in which heat flow was, so to speak, prohibited in the previous heating phase.

Therefore, if this "insulating layer" is designed to be highly thermally insulating, good heat absorption and an unsatisfactory cooling effect are achieved, whereas if the "insulating layer" is made of a material that conducts heat well, the initial thermal insulation suffers when the cooling effect is good.

This problem has also been recognized in the laminating device for producing identification cards known from European patent specification 0 154 970, where it is pointed out that such laminating devices have so far consisted of a heating element formed by glass fiber mats, which is directly adjacent to a metal block with a cooling fin, and between which resistance conductor tracks are arranged. Therefore, a significant part of the heat initially generated flows into the metal block, which is heated up as well, and cooling can only take place after the card blank has been welded, because otherwise the required welding temperature is not reached during welding. Only after welding does the heated mass of the metal block have to be cooled down. From this it can be seen that in the previous cooling devices the various functions of the mentioned cycles were mainly realized by a correspondingly precisely measured time control and the resulting disadvantages could be shifted to a manageable range, whereby it cannot be prevented that with a comparatively long overall cycle (heating and

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subsequent cooling) must be expected, which is always between half a minute and several minutes, with considerable heat losses - in this EU patent 0154 970, however, only a few seconds are mentioned. In another known device (US patent 4 108 713), which is also suitable for laminating identification cards, the flat heating element usually used for a laminating process is explained in more detail and consists of a carrier plate with a low mass and correspondingly low heat capacity, so that both the heating process and the subsequent cooling process can be carried out very quickly, with the metal carrier plate having a thickness of less than 0.25 mm and an electrical insulating layer made of silicone rubber being arranged between the actual flat heating element and the carrier plate. The flat heating element comprises meandering flat resistance wires, adjacent to which a heat sensor is arranged for temperature control.

The invention aims to remedy this situation and to reconcile and meet the essentially contradictory requirements of ensuring simultaneous good thermal insulation (during the heating process) and subsequent rapid, flawless and unhindered cooling of the laminated product.

Advantages of the invention

The invention achieves this object with the features of claim 1 and has the

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The advantage is that the entire laminating process is quick and can be completed with a high quality of the product produced, i.e. the identification card or other laminate, because the thermoplastic material behavior of the laminate layers is favored by precise, highly effective partial processing steps (heating - cooling).

The efficiency of the heating increases significantly, as there is practically no more heat loss, so that the plasticizing and fusing process begins with a steep rise in temperature and ends after a short period of exposure, whereby the cooling effect is also significantly improved by the fact that, due to the valve effect achieved by the components involved in the lamination process, the flow of the heat present at the end of the heating sub-cycle takes place completely unhindered, whereby at the same time an additional controlled cooling effect is also possible.

The measures listed in the subclaims enable advantageous further developments and improvements of the invention. The asymmetrical design of the pressing tool is particularly advantageous in that it is only heated from one side with complete insulation on this side and on the other side of the layers to be joined or laminated to form a laminate, heat flow is blocked during the heating process, while the subsequent cooling phase effectively exerts a cooling effect due to the switchability of the components involved in their heat/cold behavior, in particular of the Peltier elements.

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drawing

Embodiments of the invention are shown in the drawing and are explained in more detail in the following description. They show:

Fig. 1 is a highly schematic view of only the pressing tool area of the laminating device in sections and in cross-section and

Fig. 2 shows a possible structure for the upper or lower press die of the press tool, whereby the individual components and layers involved, including a Peltier element layer, are layered into a housing-shaped box frame and positioned close to one another by screwing the last press plate layer.

Description of the embodiments

The basic idea of the present invention is to introduce a pronounced valve effect for the heat/cold behavior of one of the elements or parts involved in the construction of the stamp in the area of the pressing die of the pressing tool in at least one of the pressing dies, so that in the course of the entire manufacturing process for the two different partial cycles of warming or heating on the one hand and cooling on the other hand, completely different behaviors of this component can be realized, the behavior of which is switched over in the course of the individual laminating partial phases.

It is understood that the structure shown is only

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This is one of the many possibilities that arise when a structural component of one or both press dies that performs a valve function on the cold/heat balance of the press tool is included. For example, it is possible to arrange components (Peltier elements) with valve functions on both sides, which either, when switched over accordingly, exclusively provide the necessary heating effect to reach the plasticizing temperature for the lamination process or are supported by the arrangement of additional heating elements on one or both sides and, on the other hand, are switched in their heating or cooling behavior at the moment of the cooling phase, so that cold is radiated onto the laminate that has just been heated for the cooling process, which is not or not exclusively generated by an external cooling effect of other press parts involved, but directly by switching the Peltier element by switching the polarity of the current feeding the Peltier element.

A variety of variants are possible here, in that heat sinks can be connected to the active valve function component in one or both press dies, which dissipate excess heat from these components, which are preferably always designed as flat Peltier elements, because a Peltier element always generates heat on one side when it generates cold on the other side.

In the embodiment shown in Fig. 1, the pressing tool consisting of an upper pressing die 11a and a lower pressing die 11b is provided with

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10 and has a number of other bearing and functional parts not shown in the drawing, including the entire timing control mechanism. Since these parts are known in themselves, they do not need to be discussed further here.

A possible component layering of the functional parts involved, for example in the lower stamp 11b, can then look like this: a surface heating layer 14 is connected to a first pressing plate 13 that is directly facing the inserted laminate 12, the structure of which does not need to be discussed further. The pressing plate 13 consists of a material that is as hard and stable as possible and has good thermal conductivity, whereby a thin brass plate can preferably be used. In a further embodiment, this brass plate can consist of so-called tin-nickel-plated hard brass, with a thickness of, for example, 0.3 mm.

In this context, it should be noted that all dimensions given below are merely given as examples and for better understanding and do not limit the invention, since depending on the type of material to be laminated and the structure of the pressing tool, dimensions that can be determined by empirical tests and which are sometimes significantly different can prove to be useful.

As already mentioned, this pressing plate 13 is followed by the flat heating layer 14, the structure of which can, for example, be as described in the US patent 4 108 713 mentioned above.

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explained; usually a common part that can also be purchased is a meandering flat band resistance heating layer that is vapor-deposited onto a plastic carrier layer, whereby the plastic carrier layer can be a very thin Capton film.

So that the metallic pressing plate 13 does not short-circuit the resistance heating strip line, the surface heating layer 14 can be connected to the pressing plate in such a way that its electrically insulating Capton carrier film faces the pressing plate 13 - if necessary, this is self-adhesive, whereby the connection of the individual layers involved in the stamp structure is preferably always carried out by gluing.

Therefore, the surface heating layer 14 is also followed by an adhesive tape 15, which is as double-sided as possible and which only serves the purpose of connecting the individual layers to one another, because the structure described so far is supported or borders on a further, heat-insulating layer 16, which is provided instead of the previously usual metallic carrier plates and whose material properties are such that, at least in the embodiment shown, no more heat is dissipated in the lower stamp area, but instead of a heat sink, an insulator is arranged, made of a non-heat-conducting or heat-insulating material, for example epoxy, glass, etc.

In contrast to this, the structure of the upper stamp is such that a pressure output is applied to the press plate 13', which is also provided here and faces directly towards the laminate layers 12 to be laminated.

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The leveling layer 17 can still be connected, in turn, to the press plate 13' via a double-sided adhesive film 18, which, like the double-sided adhesive tapes or adhesive films otherwise used, has a very low thickness, for example only 0.002 mm. In the drawing representation, no consideration is given to the respective thickness dimensions. For a better understanding of the sequence, the layers are all drawn with the same thickness, for example.

The component 19, which has a real valve function in terms of its heat/cold behavior, is therefore connected to the press plate 13' of the upper stamp 11a, which has good heat conduction, separated only by the thin pressure equalization layer of, for example, 0.03 mm, which has very good heat or cold conduction and can be made of, for example, silicone rubber, and which has a real valve function in terms of its heat/cold behavior, which in the special embodiment is a Peltier layer. A heat sink, which also has ribs for better heat dissipation, can be connected to the Peltier layer at the top (always seen in the plane of the drawing in Fig. 1).

The following function then results from such a structure or from a comparable pressing tool, each of which has a valve function component, whereby it is pointed out again that the only decisive factor in the invention is this valve function component, not the layer structure of the two pressing tool stamps described in detail above, since this can also be varied depending on the requirements, the cost specification for the end device, the layers to be laminated together, the desired speed of the lamination process, etc.

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can be trained differently.

After the laminate 12 to be laminated has been placed in the open press dies 11a, 11b, these are closed by an external, sometimes very considerable pressure, and the heating is activated. This can be done, for example, simply by supplying the Peltier element, as in the following representative of all conceivable components that perform a heat/cold valve function (for the sake of simplicity, this component will only be referred to here), with a current of such polarity that heat is radiated in the direction of the laminate 12.

For this purpose, an additional Peltier element could also be installed in the lower press jaw or the lower press jaw could, for example, be designed in exactly the same way as the upper press die.

However, in the representation of Fig. 1, it is preferred to proceed in such a way that the surface heating layer 14 is specifically switched on. This amount of heat generated by the surface heating layer 14 is directed exclusively towards the laminate 12, since a heat-insulating material, as mentioned, is connected to this heating layer on the opposite side. This also results in particularly effective heating, compared to the previously known laminating devices, which is preferably further enhanced by the fact that in this phase the Peltier element is also already subjected to a current with such a polarity that a heating effect is directed towards the laminate 12.

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Alternatively, the Peltier element could remain passive during this heating phase, i.e. not exert a cooling/heating effect in either direction, i.e. be switched off.

As soon as the heating 14 is switched off after the lamination or plasticizing temperature has been reached, if necessary with a switch-off or now switching of the Peltier element effect, the Peltier element is now subjected to a current of reverse polarity or, if it has previously remained passive, to such a current that a cooling effect is produced in the direction of the laminate 12 that is now to be cooled. This leads, as is easily understood, to a particularly rapid dissipation of the heat effect, which only occurs for a very short time anyway, also because, as with conventional devices, the actual components that generate the heat energy have only a very low heat storage capacity due to their small thickness, i.e. ultimately their mass.

If the Peltier element acts during the heating phase either, namely in the non-activated state, at least partially as an insulating layer and in the activated state it effectively contributes to the heating, whereby in the latter case the amount of heat applied by the heating surface layer 14 is particularly effectively prevented from flowing away, so to speak, pushed back in the direction of the laminate 12, the Peltier element 19, after activation, i.e. current reversal, absorbs the amount of heat abruptly with its then cooled surface side, so that after a very short time the

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The cooling phase is finished and the finished laminated product can be removed.

The expert recognizes that the Peltier element in the sum of its effects necessarily generates excess heat energy, because when the Peltier element surface facing the laminate 12 is cooled, heat is generated on the opposite surface, which is partially neutralized again by the heat effect then occurring on this surface when the pole is reversed, but heat then occurs on the other side of the element, so that overall the ribbed heat sink still connected to the Peltier element 19

20 according to Fig. 1 makes sense, so that ultimately a thermal equilibrium state is established.

A possible stamp structure can be designed according to the schematic representation in Fig. 2 in such a way that in a box-like frame

21 the individual components including the Peltier element can be layered, whereby the frame can optionally have cooling fins 22 on the side facing away from the pressing plate 13, 13' if it is used for the upper pressing stamp 11a, for example; the compressed layer structure within the housing frame can then be achieved by screwing the pressing plate 13, 13' directly facing the laminate 12 to the frame at the edge in a suitable manner, as indicated at 23. By screwing, a correspondingly high pressure is exerted on the layer structure of the respective stamp, so that the double-sided adhesive tapes or films inserted between them can also be dispensed with if necessary.

Claims (1)

2508/ot/wi 10.12.1991 - 15 - In summary, the heat/cold valve function element used, specially designed as a Peltier element, serves as an effective heat dissipation device in the cooling phase, since the heat energy present at the end of the heating phase is sucked away in a matter of seconds; alternatively or in addition, the Peltier element can also be used as a heating element during the heating phase, either alone or in support of existing conventional surface heating foils. Finally, it should be noted that the claims and in particular the main claim are attempts to formulate the invention without comprehensive knowledge of the state of the art and therefore without restrictive prejudice. Therefore, we reserve the right to regard all features presented in the description, the claims and the drawing, both individually and in any combination with one another, as essential to the invention and to set them down in the claims and to reduce the feature content of the main claim. 2508/ot/mu
09.01.1992 Company Interlock AG, Rütistr. 16, CH-8952 Schlieren Protection claims 1. Device for laminating layers of at least partially thermoplastic films, in particular identification cards, check cards, credit cards and the like carrying information and/or data, whereby the layers are connected to one another by the action of pressure and heat exerted by a pressing tool, characterized in that a component which performs a valve function with respect to the action of heat or cold is arranged in at least one of the stamps of the pressing tool (10). 2. Device according to claim 1, characterized in that the valve function component (19) is a Peltier element. 3. Device according to claim 1 or 2, characterized in that the valve function component is switched during the heating sub-cycle as a heat supplier for the laminate layer (12) to be laminated. 4. Device according to one of claims 1 to 3, characterized in that the valve function-com- /2 2508/ot/mu \,' 09.01.1992 - 2 - component is switched on as a cold supplier during the cooling sub-cycle. 5. Device according to one or more of the claims 1 to 3, characterized in that the Peltier element forming the valve function component (19) can be switched over by reversing the polarity of the supplied current after the heating part cycle has ended. 6. Device according to one of claims 1 to 5, characterized in that in both of the pressing dies (11a, 11b) forming the pressing tool (10) the valve function component (19) which generates and transmits a cooling effect or a heating effect in a targeted manner by means of a controllable power supply is arranged. 7. Device according to one of claims 1 to 6, characterized in that the Peltier element is connected to a cooling body (20) on its side facing away from the laminate layers to be laminated. 8. Device according to one of claims 1 to 7, characterized in that in addition to the valve function component (19) as a Peltier element, a surface heating foil (14) is arranged at least in one of the stamps (11a, 11b). 9. Device according to one of claims 1 to 8, characterized in that at least one of the stamps (11b) adjacent to a metallic press plate (13) directly facing the laminate layers (12) to be laminated has a surface heating resistance film (14) to which a heat-insulating layer (16) adjacent. /3 2508/ot/mü \,r -.: ■ '■■■ 09.01.1992 - 3 - 10. Device according to one of claims 1 to 9, characterized in that the layers forming the respective press stamps (11a, 11b) are connected to one another by means of adhesive films, preferably acting on both sides. 11. Device according to one of claims 1 to 10, characterized in that the heat-insulating layer (16) connected to the opposite side of the heating surface layer (14) is an epoxy layer of greater thickness. 12. Device according to one of claims 1 to 11, characterized in that the other pressing stamp (11a) in each case has a Peltier element layer (19) without a surface heating foil, which is activated at least during the cooling sub-cycle for the extraction of thermal energy originating from the heating sub-cycle. 13. Device according to claim 12, characterized in that a pressure compensation layer (17) is arranged between the press plate (13 ¹ ) and the Peltier element layer. 14. Device according to one of claims 1 to 13, characterized in that the cooling body (20) connected to the rear surface of the Peltier element layer is cooled by a cooling air flow.