Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
1999-07-08
2001-06-12
Sells, James (Department: 1734)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C156S228000, C156S288000, C156S358000, C156S583100
Reexamination Certificate
active
06245167
ABSTRACT:
The invention relates to a multistage (platen) press for manufacturing laminated plastic cards, such as check cards, credit cards and the like, in particular contactless cards with integrated electronic components, wherein several film stacks to be pressed lie on platens of the press, which are arranged on top of each other and can be vertically displaced, wherein each platen includes a heating unit and at least a few platens are provided with a specific weight equalization, and the pressing operation proceeds by lifting the platens until they rest on each other under pressure. In addition, the invention relates to a process for manufacturing plastic cards of this type.
In conventional laminated plastic cards, such as check cards, credit cards, telephone cards, which consist of several laminates pressed together under the influence of heat, the electronic components, such as data storage media, magnetic strips, or chips, are placed in the outer areas of the card. However, in the so-called contactless cards and similar cards they are no longer arranged uncovered, but instead are integrated in the interior of the card. The input or output of data, or in general the signal transfer, occurs therein in a contactless manner by induction. For this purpose, the electronic component usually has an antenna, which is likewise covered and runs inside the card.
In both types of cards, the electronic components are embedded or pressed-in in such a way that, on the one hand, a total bond of the laminate results and, on the other hand, damage to the electronic components during the press-in operation is ruled out.
In order to prevent a material displacement of the inner layers by the electronic component, in particular the chip and its carrier, suitable openings or recesses are provided in the inner layers, into which the electronic components fit.
Tests by the applicants have shown that tolerances in the electronic components, on the one hand, and the plastic films, on the other hand, are responsible for either the mentioned openings not being completely filled by the electronic components or the electronic components overhanging, and thus resulting in a material displacement or material compaction. Localized depressions on the laminate surface thereby result from the unfilled openings, whereas material displacements become apparent from slightly raised areas on the surface.
Proceeding from this background, the object of the present invention is to eliminate the problems mentioned, in particular to provide a platen press with which absolutely planar card surfaces can then be obtained, even if the aforementioned tolerances occur, are exceeded or become negatively mutually amplified in the components and plastic films. As a result, plastic cards should thus be able to be generated, which are characterized by an absolutely flat, error-free decorative print.
This object is achieved according to the invention in that above the uppermost platen of the platen press, a heating plate is arranged which for its part is mounted to be vertically displaceable and acts together with a pressure or path sensor to control the pressing operation, that the platens lying above the pressing table are each connected to a separate lifting element to create an individual weight equalization, and that the aforementioned lifting elements are each connected via their own control units to a pressure medium source.
Thus, according to the invention, the upper stop, which limits the lifting movement of the platens during the pressing operation, is formed by a movable heating plate. In this way, the pressure build-up can be controlled during the pressing operation in a substantially more sensitive manner than with a fixed stop.
In addition, all platens, except for the platen lying on the pressing table, are respectively connected to their own lifting element, and each of these lifting elements is connected via its own control component to a common pressure medium source. For each platen the lifting force can thereby be adjusted individually and, indeed, either with a fixed pre-adjustment or as a function of the individually detected weight of each platen. The desired press-on pressure can thereby be obtained for each platen.
Preferably, the heating plate acts together with a pressure or path sensor, so that in the heating phase, as well as after reaching the thermoplastic condition of the film stack, an exact control of the pressing operation is ensured. In this manner, one can at first drive the press only up to the point where all platens, with the film stacks lying on them, are in contact with each other, and the uppermost uncovered heating plate, which functions as a movable stop, is lifted only to the point where the pressure or path sensor comes to act. At this stage, which is comparitively almost pressureless, the film stacks are heated up until reaching the thermoplastic condition, and only after that does the actual pressing operation occur and, indeed, at such a low pressure gradient that the plastic material can fill cavities in the vicinity of the electronic component and, when the electronic component overhangs, can flow away without exerting critical reaction forces on the electronic component.
In order to ensure an especially sensitive driving together of the platens until they lie on the uppermost heating plate, it is recommended to connect them likewise to a lifting element, which causes a specific weight equalization for the upper heating plate. The heating plate thus does not act with its entire tare weight on the film stack located beneath it, but instead acts only with a clearly reduced force, whose strength can be controlled via the lifting element. This lifting element can be activated just like the lifting elements for the platens by motor, hydraulically, mechanically, but preferably pneumatically, and can be connected, for example via a control unit, to a pressure medium source.
For cost reasons, it is recommended to construct the heating plate in a manner similar to the platens lying beneath it. This also applies in regard to the lifting element allocated to it to create an individual weight equalization.
It is generally to be noted for the weight equalization that using it not only allows the weight of the table plates or heating plates, but also the film stack lying on it, to be more or less equalized. The so-called lifting elements each have a separate control unit for this purpose.
In spite of the described weight equalization, undesired load peaks can occur on the film stack when moving the pressing table up and, indeed, each time that a film stack moving upwards strikes against the next highest platen still found at rest, since this platen must then be accelerated from zero speed to the lifting speed. So that the forces of inertia to be overcome here are reduced, it lies within the framework of the invention to connect all platens with an individual, separate lift drive, which then already lifts the next highest platen upwards before the platen arriving from below collides. The platens are thereby no longer exposed to the full speed difference when they collide. This additional individual drive can be so designed that all platens move up simultaneously, wherein the speed of the lower platens must be higher than that of the upper platens, so that all platens reach their upper end position at approximately the same time.
This simultaneous drive of all platens at graduated speeds can occur, for example, via rotating traction mechanisms such as chains or the like, whose drive gears have different diameters. All drive gears can thereby be arranged on the same shaft, but because of their different diameters, they generate different rotational speeds on their respective traction mechanism.
Instead of this, however, the drive can also occur via the already mentioned lifting elements, in such a manner that these not only cause a static weight equalization, but also trigger a real lifting movement on each platen, controlled via their control units, before the adjacent platen arriving from below strike
Akin Gump Strauss Hauer & Feld L.L.P.
Robert Burkle GmbH
Sells James
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