EP1663619A2

EP1663619A2 - Method for applying a seal

Info

Publication number: EP1663619A2
Application number: EP04764677A
Authority: EP
Inventors: Markus Hartmann; Waldemar Wiewiora
Original assignee: Veka AG
Current assignee: Veka AG
Priority date: 2003-09-22
Filing date: 2004-09-01
Publication date: 2006-06-07
Also published as: DE102004012586A1; WO2005037528A2; WO2005037528A3

Abstract

The invention relates to a method for applying a seal (13; 13') to a lightly coloured semifinished product (11') that is covered with a surface protection film (12') coloured in a partially transparent manner. According to said method, if the semifinished product has an average peak-to-valley height Rz of between 10 and 60 µm, the pressure rollers (21, 22') are provided with an embossed relief (23') consisting of an elastic material, by which means the surface protection film (12') is applied to the rough surface of the semifinished product (11'), in the region of the embossed relief (23'), with the adhesive layer thereof, and to the surface of the semifinished product (11'), only partially in the region of the protuberances, in the region outside the embossed relief (23'). For semifinished products with a low peak-to-valley height, a surface protection film with at least three layers is used, at least one of said three layers being a marking layer that has a lower stretchability than a carrier layer and is coloured in a partially transparent manner in such a way that it contrasts with the carrier layers. Before being applied to the semifinished product, the surface protection film is guided between an elastic counter-pressure roller and an embossing roller comprising at least one embossing die with raised sections corresponding to the contours of the seals, and is partially overstretched on said sections until the marking layer coloured in a partially transparent manner cracks, thus forming a long-lasting seal.

Description

Process for applying a seal mark

The invention relates to a method for applying a sealing mark to a semifinished product to be covered with a surface protective film, with the following method steps: feeding the semifinished product to a coating device with at least one pressure roller, supplying the partially transparent surface protective film provided with an adhesive layer and laying the surface protective film with the adhesive layer on a flat surface of the semi-finished product, passing the semi-finished product coated with the surface protection film under the pressure roller.

However, this is not applicable to sheets with a smooth surface, so-called compact sheets or Celuka sheets with a foam core and dense surface, since the small air pockets created in the process of the master patent application, which are visually perceivable as different blue colors, with long storage times and correspondingly high pressure are printed out within the stack of stacked plates, whereby the seal mark simply disappears and is no longer perceptible. Such protective films cover the visible surfaces, for example of furniture surfaces, household appliances, window profiles or plastic foam panels, as protection against damage and dirt during transport and during assembly by the manufacturer. They are provided with an adhesive layer, the adhesion of which is set in such a way that, after assembly, the film can be easily removed by hand without any residues remaining on the covered surface.

Semi-finished products such as plastic sheets are often not permanently marked with a brand or any other indication of origin because they should not be visible on the visible surfaces of the workpieces made from them. At the same time, the manufacturer of the semi-finished products is interested in identifying original goods manufactured by him on the market and thus protecting himself from imitations with possibly lower quality. Printing the surface protection film before placing it on the semi-finished product is possible for this purpose, but it is relatively more expensive. Appropriate printing entails costs that are hardly justifiable for large-scale packaging that can be disposed of after only a short period of use.

The task therefore arises of applying the surface protection film at the same time in a cost-effective manner to a tamper-evident seal mark on a semi-finished product with a smooth and dense surface.

According to a first embodiment, this object is achieved by a method having the features of claim 1. According to the invention, the surface protection film is locally overstretched by a sharp-edged embossing stamp, so that the pigmented marking layer of the multilayer film used in the process of the invention tears open and a light color remains in the stretched area. The seal mark produced in this way is irreversibly incorporated into the surface protection film. The embossing dies print the film against a smooth rubber roller as a counter-pressure roller, specifically from the adhesive side. The web thus pretreated is then placed on the plate and printed on.

The surface protection film preferably comprises two transparent carrier layers, between which a colored marking layer is arranged. In the areas where the marking layer is destroyed after embossing, the view of the semi-finished product underneath, which should be colored in contrast to the marking layer, is clear. For example, the marking layer could be colored blue and the semi-finished product white. In the case of transparent support layers, the seal mark then appears as a white imprint in the blue surface protection film.

Further advantageous refinements of the method according to the invention can be found in the further subclaims 3 to 5.

A coating device for carrying out the method of the invention comprises at least: a feed device for a semifinished product, a film feed device for a surface protection film, an embossing roller with at least one embossing stamp with raised webs corresponding to the contours of the sealing marks, which embossing roller abuts at least with the webs of its embossing stamp on an elastic counter-pressure roller; and at least one pressure roller for pressing the surface protection film onto the semi-finished product.

A spreading roller known per se is preferably provided between the embossing of the sealing marks and the application of the film to the plate, so that the formation of folds and bubbles on the surface protection film applied is substantially reduced.

The embossing stamps are preferably applied to a bushing which can be pushed onto the stamping roller, so that they can be easily replaced and, depending on the width of the semifinished product produced, can be arranged next to one another in more or less large numbers.

According to a second embodiment of the invention, the object is achieved by a method with the features of claim 10.

This embodiment is particularly suitable _for semi-finished products with a roughness depth R _z of 10 ... 60 μm. The pressure rollers are provided with at least one raised relief made of an elastic material, through which the surface protection film in the area of the relief with its

Adhesive layer is applied to the rough surface of the semi-finished product and is only partially applied to the surface of the semi-finished product in the area outside the relief in the area of the roughness peaks. Thus, in the area of the relief relief, which can display a company logo, etc., there is an almost full-surface application of the surface protection film, it being clear to the person skilled in the art that, on a microscopic scale, individual air bubble inclusions can still be present or in particularly narrow ones Deepening of the surface no adhesion of the film can be achieved. Due to the almost full-surface contact with the rough surface, light refraction takes place predominantly in the boundary layer between the adhesive side of the surface protection film and the covered surface of the semi-finished product, so that the color of the transparently colored surface protection film appears particularly intensely here. At a very flat viewing angle, the seal mark is visible through reflection.

On the other hand, the areas outside the relief in relief are only printed to such an extent that the surface protection film is mostly only adhered to the raised areas of the rough surface. As a result, part of the light passes through the film in the non-adhering areas and is reflected on the lightly colored surface of the semi-finished product. In the case of a blue-colored surface protection film, for example, which is placed on a white semi-finished product, the colors of the film and the semi-finished product underneath mix for the viewer, so that the film appears lighter here.

This results in the very essential advantage of the invention that the printing of fonts and graphics is only possible by simply applying raised embossing stamps to the pressure roller that is already present and required. However, the protective film from the semi-finished product peeled, the seal mark produced according to the invention is irretrievably destroyed, so that it is not possible to destroy semi-finished products from a third-party manufacturer with a surface protection film of the original goods without destroying the seal mark.

The seal marks make semi-finished products recognizable to everyone as original products from a particular manufacturer. The seal brands preferably represent a company logo or other protected brands of the manufacturer. It is then difficult to imitate the semi-finished products, since the delivery without the seals shows the user that he does not have the desired original goods: If the seals were applied to imitation products, the violation of the brand would automatically be fulfilled.

Surprisingly, in order to form a relief relief according to the invention on the pressure roller, it is sufficient to glue the latter with cuts of a self-adhesive film. The necessary pressing forces for the application of the film or the pre-pressing forces to achieve the effect according to the invention are so low that error-free production over several weeks is possible with such simple means. The film cuts can also be easily removed, replaced, etc. without damaging the pressure rollers.

Surprisingly, the use of a stone chip protection film for the automotive industry has proven to be particularly suitable. This shows good adhesion to the pressure rollers and, with its relatively large thickness and good elastic properties, is the origin lend were designed to cushion the impact of stones on paint parts of vehicles, n particularly suitable for the method according to the invention.

The elasticity of the applied relief is essential to the invention. This must be adjusted so that the surface protection film is pressed almost over the entire surface onto the rough surface of the semi-finished product, so that the relief relief deforms elastically without damaging the surface of the semi-finished product.

A coating device with the features of claim 8 is particularly suitable for carrying out the method. It is advantageous here that the only difference to the existing systems is the relief reliefs applied to at least one pressure roller. By using a cut of a self-adhesive plastic film with the appropriate elasticity and thickness, this coating device can be easily manufactured by retrofitting.

The invention is explained in more detail below with reference to the drawing. The figures show in detail:

Figure 1 shows a coating device for the first embodiment of the method in a schematic side view.

FIG. 2 a perspective roller of the device from FIG. 1 in a perspective view; FIG. 3 shows the structure of the surface protection film for the first embodiment of the procedure in a schematic sectional view;

4 shows a coating device for the second embodiment of a method in a schematic perspective view; and

5 shows the contact point of the semi-finished product and the pressure roller in the device according to FIG. 4 in a schematic sectional side view.

A first coating device 100 is shown schematically in FIG. This can be set, for example, over the extraction area of a plate extrusion system. A semifinished product 20 is withdrawn from the extruder via take-off rollers (not shown) and fed to a packaging system in which the endless semifinished product 20 is cut and palletized.

On a pressure roller 21, a surface protection film 12, which has an adhesive layer on its underside, is placed on the semi-finished product 11 and printed on it.

On a frame 30, film feed devices 31, 32 are attached, which can be used alternately, so that the surface protection film 12 can be fed continuously and even if the supply roll for the surface protection film 12 changes, there is no need to interrupt the plate production.

The surface protection film 12 drawn off from one of the film feed devices 31, 32 is guided over a pair of rolls which consists of a counter-pressure roll 22 with an elastic coating and a stamping roll 23. In order to be able to place the surface protection film 12 free of bubbles and wrinkles on the semifinished product 11, a spreader roll 27 can also be provided behind the pair of rolls 22, 23, the outward-directed spiral profile of which causes a slight pre-stretching transversely to the pull-off direction.

Fig. 3 shows the structure of the surface protection film 12 in section. A colored marking layer 12.2 lies between transparent or partially transparent carrier layers 12.1, 12.3. This can either be partially transparent or opaque. It is only essential to the invention that it differs visually and that a color contrast arises in those areas in which the marking layer 12.2 is destroyed by overstretching. The surface protection film 12 is coated on one side with an adhesive layer 12.4, preferably a pressure sensitive adhesive, which enables good adhesion to the semi-finished product 11, but at the same time also allows the surface protection film 12 to be removed easily and without residues after the semi-finished product 11 coated in this way has been processed.

Fig. 2 shows the prague roller 23 with counter-pressure roller 22 in a perspective view. In addition, a deflection roller 26 is shown, which is not shown in FIG. 1. The embossing roller 23 has, in the embodiment shown, pushed-on bushes with embossing dies 24, which have an engraved relief. The relief has raised webs 25, the height of which is selected in coordination with the depth of penetration into the elastomeric coating of the counter-pressure roller such that local expansion of the surface protection film 12 takes place to such an extent that the colored marking layer 12.2 tears, whereas the tra - layers 12.1, 12.3 are so elastic that their expansion largely resets after passing through the die 24. What remains is a seal mark, which is formed by the visible cracks in the marking layer within the surface protection film 12.

In the method according to the invention, therefore, a surface protection film with at least three layers is used, at least one of which is a marking layer which has a lower stretchability than a carrier layer and which is colored in a color-contrasting manner to the carrier layers in a partially transparent manner. According to the invention, between the feeding of the surface protection film and the placing on and pressing on the semi-finished product, the further process step is provided to locally stretch the specially designed surface protection film to the crack of the marking layer by means of the embossing stamp. The cracks thus created remain visible and together form a seal mark that is permanently visible even on very smooth surfaces.

4 schematically shows a second coating device for applying sealing marks 13 'to a semifinished product 11' to be covered with a surface protection film 12 ', which at least comprises: a feed device for a semifinished product 11', for example an extruded plastic sheet, a film feed device 20 'for a surface protection film 12', and pressure rollers 21 ', 22' for pressing the surface protection film 12 'onto the surface of the semi-finished product 11'. The pressure roller 21 'is provided with embossing reliefs 23', which are formed from blanks of an elastic, self-adhesive PVC plastic film with a thickness of approximately 325 μm. The embossed reliefs 23 'produce sealing marks 13' on the semi-finished product 10 covered with the surface protection film 12 'and ready for sale. The sealing marks 13' are destroyed again by detaching the surface protection film 12 'from the finished semi-finished product 10.

A film made of polyethylene with a thickness of 30 to 50 μm, for example, is suitable as the surface protection film 12 '. In order for it to adhere, it is coated on at least one side with an adhesive or tackifier, for example with an acrylic layer or a natural rubber. The adhesion is set in such a way that there is sufficient adhesion when transporting the semifinished product 10, but that the surface protective film 12 'can also be removed easily and quickly from the plastic sheet 11'. In the case of a polyolefinic surface protection film which is coated with an acrylic-based tackifier, the linear adhesive value measured according to the AFERA 4001 standard is, for example, approximately 65 cN / cm.

The surface protection film 12 'is transparent and preferably colored in a clearly visible color contrast to the semifinished product 11', so that the sealing marks 13 'designed according to the invention can be recognized even from a distance and even under unfavorable light conditions.

The method according to the invention can be used in all systems of semi-finished products and surface protection films in which the rigidity of the surface protection film is combined with the roughness of the semi-finished product offers the possibility of achieving the effect of a differently intense coloring described below in order to produce a seal mark. Particularly suitable for the application of the method according to the invention in connection with a polyolefinic surface protection film with a thickness of 20 to 100 μm, in particular 40 μm, is a semi-finished product made of hard PVC, the surface of which is to be coated is relatively rough. The roughness is characterized by the following key figures measured according to DIN ISO 4287 and 4288: a maximum roughness depth R _max of 10 to 80 μm, an average roughness depth R _z of 10 to 60 μm and an arithmetic mean roughness value R _a of 2 to 10 μm

As shown in FIG. 5 in particular, the thickness of the self-adhesive PVC plastic film must be selected as a relief in such a way that the surface protection film 12 'is pressed into the roughness tips of the surface of the semi-finished product 11'.

In the areas outside the relief relief 23 ', the surface protection film 12' only rests on the tips of the surface of the semi-finished product 11 '. As a result, light passes through the transparent film 12 'and allows the color of the semifinished product 11' to shine through from the back.

In the areas of the surface protection film 12 ', on the other hand, which is printed by the relief 23' into the rough surface of the semi-finished product 11 ', there is a predominant part of the surface of the film 12' directly adhering to the surface structures of the semi-finished product 11 '. The influence of the translucent color of the Semi-finished products weaker. There is an increasing amount of light refraction at the boundary layer of the colored surface protection film 12 ', so that its color appears more intensely.

If the surface protection film 12 'is removed, it is pulled out of the microscopic surface structure of the semifinished product 11'. The surface protection film 12 'is deformed; The embossed microscopic structures are mostly destroyed again, so that the surface of the film is smoothed again. The seal mark 13 'is in any case destroyed, because when the surface protective film 12' is re-applied by hand, only a superficial contact of the film occurs at the roughness tips of the semi-finished product. It is therefore impossible that the surface protection film 12 'of the original manufacturer can be placed on semi-finished products from a third party. The seal mark 13 'cannot be restored without the original embossed reliefs 23'.

In addition to the preferred continuous application of sealing marks 13 'directly to the withdrawal devices 21', 22 'in the manufacture of semi-finished products, it is also possible to use hand-held embossing stamps with embossed relief.

Claims

Claims:

1. A method for applying a sealing mark (13) to a semi-finished product (11) to be covered with a surface protection film (12), with the following method steps:

Feeding the semi-finished product (11) to a coating device with at least one pressure roller (21), feeding the partially transparent surface protection film (12) provided with an adhesive layer and placing the surface protection film (12) with the adhesive layer (12.4) on a flat surface of the semi-finished product (11), passing the semi-finished product (11) coated with the surface protection film (12) under the pressure roller, characterized in that the surface protection film (12) has at least three layers, at least one of which is a marking layer (12.2) which is a smaller one Stretchability has as a backing layer (12.1, 12.3) and which is colored in a partially transparent manner in a color contrast to the backing layers (12.1, 12.3) that the surface protection film (12) can be seen between an elastic layer before being placed on the semi-finished product (11) Counter-pressure roller (22) and a stamping roller (23) with at least one embossing stamp (25) raised webs corresponding to the contours of the sealing marks are passed through and partially stretched on the webs until the cracking in the partially transparent colored marking layer (12.2).

2. The method according to claim 1, characterized in that the surface protection film (12) comprises two transparent carrier layers (12.1, 12.3), between which a colored marking layer (12.2) is arranged.

3. The method according to any one of claims 1 to 2, that the surface protection film (12) has a thickness of 10 to 100 microns.

4. The method according to any one of claims 1 to 3, that the elongation at break of the marking layer is less than the elongation at break of the carrier layer.

5. The method according to any one of claims 1 to 4, that the average roughness depth R _{z of} the surface of the semi-finished product (11) is less than 80 microns.

6. Coating device (100) for carrying out the method according to at least one of claims 1 to 5, with at least: a feed device for a semifinished product (11), a film feed device (31, 32) for a surface protection film (12), a stamping roller (23) with at least one embossing stamp (25) with raised webs corresponding to the contours of the sealing marks, which embossing roller (23) at least with the webs of its embossing stamp (25) rests on an elastic counter-pressure roller (23); and at least one pressure roller (21) for pressing the surface protection film (12) onto the semi-finished product (11).

7. Coating device according to claim 6, characterized in that the embossing stamp (25) is applied to a bushing (24) which can be pushed onto the stamping roller (23).

8. Coating device (100) according to claim 6 or 7, characterized in that an spreader roller (27) is provided between the pressure roller (21) and the stamping roller (23).

9. Coating device (100) according to one of claims 6 to 8, characterized in that the counter-pressure roller (22) consists of rubber with a hardness of 5 ... 100 Shore-D.

10. A method for applying a sealing mark (13 ') to a semi-finished product (11') to be covered with a surface protection film (12 '), with the following method steps: feeding the lightly colored semi-finished product (11') to a coating device with at least one pressure roller (21 ', 22'), - feeding the partially transparent colored surface protection film (12 ') provided with an adhesive layer and placing the surface protection film (12') on a flat surface of the semi-finished product (11 '), Passing the semi-finished product (11 ') coated with the surface protection film (12') through the pressure rollers, characterized in that the semi-finished product (11 ') has an average roughness depth R _z of 10 ... 60 μm and that the pressure rollers (21, 22 ') are provided with at least one raised relief (23') made of an elastic material, through which the surface protection film (12 ') in the area of the relief (23') with its adhesive layer is applied to the rough surface of the semi-finished product (11 ') and in the area outside the relief relief (23 ') is only partially applied to the surface of the semi-finished product (11') in the area of the roughness peaks.

11. The method according to claim 10, characterized in that the surface protection film (12 ') has a thickness of 30 to 50 microns.

12. The method according to any one of claims 10 or 11, characterized in that pressure rollers (21 ', 22') made of rubber with a hardness of 40 ... 100 Shore-A are used.

13. The method according to any one of claims 10 to 12, characterized in that the relief relief (23 ') is formed by at least one cut of a film with a thickness of at least 250 μm applied to a roller surface.

14. The method according to claim 13, characterized in that the film is a stone chip protection film made of PVC, which is provided with an adhesive layer.

5. Coating device for carrying out the method according to one of claims 10 to 14 with at least: a feed device for a semifinished product (11 '), a film feed device (20') for a surface protection film (12 '), and at least one pressure roller (21', 22nd ') for pressing on the surface protection film (12') on the semi-finished product (11 '), characterized in that the pressure rollers (21', 22 ') are provided with at least one raised relief relief (23') made of an elastic plastic film.