Electric heating – Metal heating – By arc
Reexamination Certificate
2000-04-27
2002-07-02
Elve, M. Alexandra (Department: 1725)
Electric heating
Metal heating
By arc
C219S121440, C219S121580, C083S373000
Reexamination Certificate
active
06414264
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a process for cutting laminates intended for application to the skin. These laminates include at least one film and at least one further layer and are suitable for the medicinal-pharmaceutical application to the skin.
The production of plasters from base material in the form of a web (laminate) is usually carried out, as, e.g., in DE-A 41 10 027, by mechanically punching into or punching through the laminate web. The punching knife hereby includes of a strip steel cutting tool which is, e.g., embedded and fixed in a wooden template. During the punching, the punching knife is driven onto the laminate web with a varying dynamic force according to the structure of the laminate, and punctures the laminate layers up to a determined punching depth. Ideally, the strip steel cutting tool is arranged exactly horizontally in relation to the laminate web, so that all points of the laminate along the strip steel cutting tool are punctured simultaneously and up to the same depth.
The constant repetition of these procedure steps, however, results in a deviation from the above mentioned ideal conditions in the production process which is more or less early and strong depending on the material. The reasons for this are the wear of the strip steel cutting tool on the one hand, but also the less than ideal fixing of the same in the template as well as other factors such as the not exactly horizontal lowering of the punching tool onto the laminate. This results in an increase of faulty punching processes, so that the laminate layers to be cut through are not completely severed. The following removal of the excess part of the laminate, i.e. the unchaining, is thus rendered considerably more difficult, resulting in increased material spoilage. A regular exchange of the strip steel cutting tools after certain intervals of time thus becomes necessary, which leads to increased costs as a result of the necessary machine preparation periods and starting losses. In addition, the punch dies themselves are subject to considerable wear and necessitate routine maintenance.
WO-A 95/17304 teaches a process for the cutting to size of labels which are applied to packages by means of laser beams.
WO-A 97/11841 describes a process for the production of self-adhesive labels. These self-adhesive labels are cut from a material in the form of a web by means of a cutting head using laser beams, whereby the material is held beneath the cutting head by an underpressure tightening device.
SUMMARY OF THE INVENTION
It is the object of the invention to provide a process for cutting laminates intended for application to the skin, the process having less tool wear and less material waste and being altogether less expensive than known processes of this kind through savings in machine preparation periods etc. The process should especially be highly variable, so that it is, e.g., no longer necessary to develop a separate punching press for every desired form of the laminate to be punched out.
This object is achieved by means of a process for cutting laminates intended for application to the skin comprising the following steps: a laminate comprising at least one film and at least one further layer is supplied, the laminate is transported to a cutting area of a laser beam cutting arrangement, whereby it is kept flat in the cutting area under a tension of between 0.1 N/m and 1×10
4
N/m, and it is cut into or cut through by means of laser beams.
In the process according to the invention, the tension to which the laminate intended for application to the skin is subjected is preferably at a value of between 600 and 3000 N/m, especially between 1000 and 2000 N/m. This tension can be adjusted by means of common devices located outside of the cutting area. Such devices used according to the invention can especially be conceived as tong-like pulling devices located in front of and/or behind the cutting area and operating in a fixed cycle, which, e.g., transport the material against the braking effect of a slipping clutch of the laminate supplying device or else have different pulling lengths, whereby the front pulling device, seen in direction of the laminate supply, has a slightly longer pulling length than the rear one.
According to a further aspect of the invention, a process for cutting the medicinal-pharmaceutical laminate is provided which includes the following steps: a laminate having at least one film and at least one further layer supplied, the laminate is transported to a cutting area of a laser beam cutting arrangement, whereby it is kept flat in the cutting area by means of a fixing device, and it is cut into or cut through by means of laser beams.
The two processes according to the two central aspects of the invention, as described above, can, of course, also be combined with one another.
The fixing devices can especially be conceived as a fixable framelike holding device optionally fastened on ball bearings, e.g., in the form of an “active tightening frame” (FIGS.
2
A,B) described below, or as a holding device with perforations on the upper side, whereby the relative surface proportion of the perforations, in relation to the surface of the upper side of the fixing device which faces the laser beam, is greater than 50%. Preferably, this proportion is greater than 90%, especially greater than 99%. Preferably, the perforations have a honeycombed form.
Other preferred fixing devices are transparent covering devices, e.g., made of glass, plastics such as plexiglass etc., which have an absorbing band diverging from the laminate. Devices based on combinations of the above mentioned framelike holding device, the holding device with perforations or the transparent covering device are also applied according to the invention.
According to the invention, the laminate suited for application to the skin can be flooded with inert gas during the cutting process. Using certain materials, undesired oxidation processes during cutting can thus be avoided. In addition, by supplying inert gas during cutting, vaporizing material can be blown away or sucked off, whereby impairments of the laminate surface are avoided. Such impairments can, e.g., consist in that vaporized or otherwise dissolved particles connect with the laminate surface and impair its characteristics in an undesired way. In this context, the term “vaporize” used above is to be interpreted in a broad sense. It is not only to be understood to mean that a solid material passes over into the vapor phase during the laser cutting process; rather, it also includes particles present in solid phase having a size in the realm of mm or even mm or smaller (described in the following as micro- or nanoparticles). In the following, the inert gas used according to the invention is understood to be a gas such as nitrogen, argon or helium, etc. The supply and flooding with inert gas during cutting can especially be used to support the flat resting of the laminate on the fixing device. This can, e.g., occur by means of overpressure. The gas can be supplied parallel to the laser beam and then, e.g., be sucked off my means of underpressure. For this, the holding device with perforations according to the invention can be used. On the other hand, the gas can also be supplied from the side, e.g., by means of nozzles located above and parallel to the laminate.
Of course the flat resting of the laminate can also be supported by applying underpressure to the laminate underneath the cutting area, for which the above mentioned device with perforations is especially suited. If the laminate is laid on this device for cutting, the laminate can be held flat by applying underpressure to the laminate through the perforations underneath.
The laminates for application to the skin used according to the invention are basically to be understood as all single or multilayered laminates whose materials are so constituted that they are suitable for longer-term wearing on the skin. This not only includes the known “tapes” such as Hansaplast® g, Leukosilk®, Leukopl
Elve M. Alexandra
Johnson Jonathan
Jordan and Hamburg LLP
LTS Lohmann Therapie-Systeme AG
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