MXPA00012245A - Method for marking a laminated film material - Google Patents

Abstract

The invention relates to a method for marking a laminated film material comprising at least a metal film and a plastic film material affixed to it by means of an adhesive. To ensure that the marking of the film withstands any subsequent process steps, such as sterilization of the packaging, and is visually appealing, it is envisaged that the plastic film material be removed and/or visibly changed in structure by laser.

Description

METHOD TO MARK A LAMINATED FILM MATERIAL The invention relates to a method for marking a laminated film material in a development according to the generic part of claim 1, as well as to a laminated film for packaging purposes according to the generic part of claim 18. The use of laminated films as backing sheets for blister packs is well known in packaging technology. These laminated films consist of a metal base, such as aluminum, fixed to a plastic film, which is printed on the upper side and / or the side facing the metal sheet, and a plastic film material on the lower side that can be attached to a plastic container. These laminated films are often also marked on the upper side with a variety of information, such as the expiration date, a lot number, and other markings that identify the contents of the package. If the blister pack is going to undergo other different process steps after sealing, such as sterilization by autoclaving, because the contents of the package are to be used in the field of medicine, for example, then it must be guaranteed: that the top side brand can withstand this treatment. A thermal transfer printing process for marking blister packs that are subsequently exposed to sterilization is known, for example, from European Patent Number EP-0, 646, 471. However, the result of the mark is not particularly satisfactory, because it is too full of contrasts, and therefore, can not be optimally coordinated with the packaging design. In addition, the process involves the consumption of a large amount of material. Moreover, using the present technology, the mark still has to be made on the laminate, that is, on the film which is generally wrapped around a roller, because it is not possible to mark containers that are already sealed. The invention solves the problem of marking the upper side of a laminated film, especially for blister packs, in such a way that the mark supports the subsequent process steps, such as packaging sterilization, and produces a result that is optically adequate. In addition, the process of marking must take place online in a packing plant, and must be characterized by a minimum consumption of materials. The invention solves this problem with the features set forth in claim 1 and claim 21. With respect to other substantial design features, reference is made to the dependent claims. The use of lasers makes it possible to provide marks on the upper side of the film material that are resistant to the following process steps, such as sterilization in particular, and retain their characteristics. As a result of the laser treatment, the upper plastic film is thermally changed, such that a visible color change occurs, or the part of the surface treated with the laser beam is removed to produce the desired letters . In the case of the last subtractive procedure, the upper colored layer of the film is removed to the metal substrate, which also serves as a buffer against the laser treatment, thereby eliminating the risk of perforation. If you select a plastic whose color contrasts sharply with the metallic color, then the film acquires a clearly visible mark that can be much better integrated into the visual identity of the packaging design than is possible with black and white printing. Because the underlying metal layer shows no change when the package is treated in an autoclave, the mark is not harmed after this treatment. In order for the laser to achieve a color change of the upper plastic layer, then a plastic film containing pigments whose color changes with the laser treatment is generally used. In any case, the laser allows to mark containers that are already filled and sealed, because the printing takes place on a non-contacting base with a relatively large distance between the marker and the sealing film, so that a smooth surface is not required. Further details and advantages of the invention can be seen from the following description and from the drawings. The drawings show: Figure 1 is a schematic diagram of a laser marking unit, and the printing of an acrylic film with the invention. Figure 2 is a diagram of the integration of laser marking units in a packing plant. Figure 3 is a diagram of ampule strips configured along one another. Figure 4 is a schematic diagram of the control system for several laser marker units. The laser marking unit 1 is designed to mark a laminated film, especially for a blister pack. This laminated film comprises a metal substrate, usually aluminum, fixed to a plastic film that is printed on the upper side and / or on the side facing the metal sheet, and a plastic film material on the lower side that It can be attached to a plastic container. As a result of the laser treatment in the laser marking process, the upper plastic film is thermally changed, such that a visible change in color occurs, or the part of the treated surface is removed with the beam of laser to produce the desired letters. The laser marking unit 1 preferably comprises a laser device 2, deflecting mirrors 3, and a flat field lens 4. Preferably, sealed C02 laser devices excited with high frequency without an external gas supply are used, and have a wavelength of 10.6 microns, as the laser source 2, for the subtractive marking procedure. In general, it can be assumed that gas filling has a life of approximately 20,000 operating hours. Because the laser device is pumped with HF, there is no need to pump reflectors, such as are used, for example, with solid-state laser devices. For this reason, costs are confined to the cost of energy consumption. For laser marking by means of a color change in the upper plastic film, the Nd: YAG laser device is preferably used. The laser beam 5 is conveniently deflected by mediating two revolving galvanometric mirrors 3. These operate in a closed cycle with an active stabilization of the temperature. Because the mirrors 3 have only a very low mass, which is moved, a high speed of deflection, and an accuracy of the exact path is possible. After deviation, the beam 5 is focused through a flat field lens 4 on the operating level 6. Especially, as a result of this calibrated lens and mirror system 3, 4, the focus point of the laser 2 moves in the operational plane 6.

The flat field lens 4 preferably has a focal length of 200 millimeters, providing a sufficiently large working distance. A distortion of the laser beam 5 is excluded by virtue of the axial change configuration of the rotating galvanometric mirrors 3. The mirrors 3 are controlled by a card located on the computer. In addition, an integrated beam expander provides a small diameter of the focus point, with a good depth of focus in the TEM00 mode. A small diameter of the focus point is important for the quality of the marking, especially if a work field is foreseen big. A favorable diameter of the focus point is 320 microns. Because the writing head of the laser device 2, comprising the diverting mirrors 3 and the flat field lens 4, has a distance of 200 millimeters from the surface of the film 6 to be marked, a classification is necessary of the workspace for security reasons, to protect against any interposition during the marking procedure. Due to the wavelength of the laser device 2 that is used, a Plexiglass enclosure can be used for this purpose. This offers the advantage that the marking procedure can be inspected. In addition, the design includes an interrupting device 8 for the laser beam 5, which is under electronic control, and serves to interrupt the laser beam. It is activated, for example, when the protective doors of the enclosure are opened. The laser marking unit 1 is preferably integrated in a packing plant, such that the marking of the film is completely automatic, taking place directly in line, ideally after the packaging container is sealed. Figure 2 shows five production lines 7 of a packing plant, especially for contact lenses, which continuously transport the tool carriers 9 illustrated in Figure 3, each of which is loaded with a blister strip 10. Blister strips 10 comprise five blister packs 11 configured one behind the other, which are connected to one another by a strip of film 12 corresponding in shape to the delineation of the upper side of the ampoule packs 11, because the Film strip 12 is attached to individual blister packs 11 after they have been filled for the purpose of packaging, preferably a contact lens. To mark the upper side of the film 12 of the blister strips 10, a stop bar 13 adapted with sensors is provided, which causes the carrier 9 with the blister strips 10 to stop briefly, in such a way that they can be marked in a firm marking position by the laser device 2. Because the deflection of the laser beam 5 is not sufficient for the five lines 7 provided in the preferred embodiment, since a movement of the laser marking unit would be very complicated. 1, it is intended that two laser marker units 1 and 100 be conveniently integrated into the packing plant, where unit 1 provides the marking for lines 1, 2, and 3, and unit 100 for lines 3, 4 , and 5. Naturally, it is also possible to design a packing plant with only one laser device, or also with more than two laser devices. As shown in Figure 4, the required marking data is fed by a process control system to the packing plant and laser marker units 1 and 100, with the data sets possibly being different for each line 7. a single line 7, the data set remains the same, until new data sets are transmitted through the process control system. The marking of line 3 is done by laser unit 1 or 100, which is the first one that remains free. The waste that occurs during the marking procedure is conveniently discharged by an exhaust air system, which is not described in more detail in the present. The present laser printing process is particularly suitable for a blister pack having a flexible laminated film cover, for example, a blister pack for contact lens. A blister package for example contact lens is disclosed in U.S. Patent No. 5,609,246 to Borghorst. In general, a blister pack for a contact lens has a rigid blister container, and a flexible laminated film cover that is bonded in a thermal or adhesive manner to the blister pack opening. The laminated cover is designed to be flexible, such that the covering material can be easily handled when the laminated covering material is applied to the package during the production process, and when the covering material is removed by the consumer. The laminated covering material has at least one external thermoplastic layer and a backing layer. The external thermoplastic layer is produced from a thermoplastic film-forming polymer, including polyolefin, for example polyethylene, polypropylene, polybutene, and copolymers thereof; polyester, for example polyethylene terephthalate, polybutylene terephthalate, and copolymers thereof; and polyvinyl chloride. The outer layer is a protective layer that provides a printable surface, and the backing layer provides moisture and gas barrier properties. Suitable materials for the backing layer include metals, for example aluminum; and thermoplastic polymers, for example polyolefin, polyester, polyvinyl chloride, polyvinyl alcohol, or acrylonitrile polymer, although a metal is preferred. Preferably, the backing layer is produced from a material having a thermal decomposition temperature higher than the thermoplastic of the top layer. Additionally, the laminate covering material may have additional layers, including an inner layer of thermoplastic film, which is placed adjacent to the backing layer, such that the inner layer can act as an adhesive layer that binds the laminated film cover to the blister container. The flexible laminated film covering material can be provided as a roll, which is suitably configured for an online printing process. In general, a contact lens is produced, inspected, and placed in a blister container, together with an amount of an isotonic saline solution. The film cover, which has been cut to cover the opening and a certain exposed portion of the blister container, is then placed on the container, and is fixed or sealed, for example, thermally, to the container, around the opening. The present printing process is a highly flexible printing process that can print the flexible film cover before or after it is cut from the roll, and even after it is placed and fixed to the package. The present printing process is especially suitable for printing variable information, for example batch number, expiration date, power, and the like, on the flexible film cover. One of the advantages of the present process is that the laser printing process is a highly flexible and robust process that can impart clear and legible information, even on a non-uniformly flat surface. This flexible nature of the present invention is highly important, because the flexible laminate cover tends to form a corrugated surface, and tends to rise in the non-bonded sections. According to the above, conventional variable information printing processes, such as thermal transfer processes and inkjet processes, which require a flat surface to print properly, are not highly suitable for printing information after that the cover is sealed over the container. In addition, because a contact lens package is sterilized, usually in an autoclave, after the cover is sealed to the container, the ink applied on the cover is subjected to a high temperature and a moisture environment, which promotes the thermal degradation of the applied ink, and also prevents having legibility of the printed information. In contrast, the present process does not use an ink system to impart information about the cover, and therefore, the sterilization process does not affect the readability of the printed information. According to the above, a preferred embodiment is that the laminate cover material is printed after the cover material is attached to the package, using the laser printing process. According to the present invention, the upper layer and the backing layer of the laminated covering material have a color contrast, such that, when the laser removes a pattern from the upper layer, the pattern is clearly visible. For example, when a pigment or blue dye is added to the thermoplastic formulation for the top layer, and an aluminum layer is used as the backing layer, a highly readable message can be imparted on the cover material, removing or ablating the top layer to form a pattern of letters or a graphic design. The marking results obtained using a C02 laser device show that the marking of the film is characterized by a very high quality of the letters, and of resistance. The text is clearly legible, and was distinguished by a high degree of resolution. The upper colored layer of the film is removed to the metal substrate, where it has been shown that, when aluminum is used as the substrate, it provides a good buffer for laser treatment, and no perforations occur during the process. Above all, the marking is of a pleasant appearance, and matches well with the design of the package. Because the process is carried out on a non-contact basis, with a relatively large distance between the marker and the sealing film, the containers that are already filled and sealed can be marked without problems with respect to clarity and resolution of the letters. Moreover, the integration of the marker unit into a packing plant has the advantage that the production process can be substantially more flexible. In addition, it has been shown that, after sterilization, the marking remains clearly legible, and is not subject to change.

Claims (26)

1. A method for marking a laminated film comprising at least one backing layer and a backing film attached thereto by means of an adhesive layer, which comprises: the removal and / or structurally visible modification of the plastic film by means of of a laser device (2).

2. A method of claim 1, which comprises a plastic film material containing pigments that change their color after their laser treatment.

A method of claim 1 or 2, which comprises the use of a film (12) exhibiting printed text on the side facing towards or away from the metal film.

4. A method of claim 3, which comprises printing with pigments that change their color after their laser treatment.

5. A method of claim 3 or 4, which comprises printing that is removed and / or visibly modified in its structure by means of a laser device (2).

6. A method of one or more of claims 1 to 5, wherein the backing layer is a metal film.

7. A method of one or more of claims 1 to 5, wherein the backing layer is a thermoplastic polymer, for example polyolefin, polyester, polyvinyl chloride, polyvinyl alcohol, or acrylonitrile polymer.

A method of one or more of claims 1 to 7, which comprises the film (12) which forms the backing sheet of a blister pack (11), and which is firmly sealed with the blister pack (11). ).

9. A method of claim 8, which comprises several blister packs (11) which are covered by a strip of film (12), and which form an ampoule strip (10).

10. A method of claim 9, which comprises five blister packs (11) that form a blister strip (10).

A method of one or more of claims 8 to 10, which comprises the film (12) which is marked by a laser device after being sealed to the blister pack (11).

12. A method of one or more of claims 8 to 11, which comprises sealing the film (12) to the blister pack (11), and in-line marking the film (12) in a packing plant.

13. A method of one or more of claims 1 to 12, which comprises the use of a C02 laser device as the laser device (2).

14. A method of one or more of claims 1 to 12, which comprises the use of Nd: YAG as the laser device (2).

15. A method of claim 13, which comprises a laser device of C02 (2) with the wavelength of? = 10.6 microns, and the focus point of the laser beam (5) with a diameter of 1,000-100 microns, and preferably 320 microns.

16. A method of one of claims 8 to 15, which comprises a stop bar (13) for the blister packs (11).

17. A method of one of claims 8 to 16, which comprises the blister packs (11) that are transported within the packing plant in several lines (7) along one another.

18. A method of claim 17, which comprises two or more laser devices (2) for marking blister packs (11) in the lines (7).

19. A method of claim 17, which comprises only a laser device (2) for dimming blister packs (11) in the lines (7).

20. A method of one of claims 8 to 19, wherein an ophthalmic lens, especially a contact lens, is packaged in ampoule packs (11).

21. A laminated film for packaging purposes, comprising at least one metal film and a plastic film material adhered on one side to the metal film, which comprises a plastic film exhibiting laser inscribed marks.

22. The laminated film of claim 21, comprising the removal of the plastic layer in the region of the laser-inscribed mark., and that makes the metallic layer visible.

23. The laminated film of claim 21 or 22, comprising a laser-inscribed marking of 1,000-300 microns, preferably 320 microns wide.

The laminated film of one or more of claims 21 to 23, which comprises a plastic film material that is translucent, and exhibits printing on the side that faces away from, or towards, the metal film.

25. The laminated film of claim 21, comprising a plastic film material that exhits pigments.

26. The laminated film of claim 25, comprising pigments that change their color in the field of laser-inscribed marking.