PERMANENT SECURITY FILM WITH HIGH TRANSPARENCY AND WITHOUT PREDETERMINED BREAKING POINTS

Abstract

The present invention relates to peelproof security films made from a poly(meth)acrylate, more particularly from a polymethyl methacrylate, which comprises at most 10 wt % of or no impact modifiers. These films are highly transparent, have good printability qualities, and can be applied without intended break points. The peelproof security films can therefore find use in particular in documents, such as passports, for example, in security labels, such as road tax badges, for example, or for product theft prevention, or as price tags. These security labels are further distinguished by good weathering stability and in particular by especially good UV stability.

The present invention relates more particularly to the use of these security labels, which have a thickness of not more than 2 mm, comprise at least 80 wt % of polymethyl methacrylate and contain no impact modification particles.

Claims

1: A security label, comprising: a polymethacrylate film, wherein the film has a thickness of between 15 and 120 m and an elongation at break of between 2.0% and 15%.

2: The security label according to claim 1, wherein the film comprises 55 to 100 wt % of a polymethacrylate which comprises 80 to 100 wt % of MMA and 0 to 20 wt % of styrene and/or other (meth)acrylates having an alkyl radical having 1 to 4 carbon atoms, and wherein the film comprises at most 10 wt % of an impact modifier or no impact modifier.

3: The security label according to claim 1, wherein the film comprises 90 to 100 wt % of a polymethacrylate which comprises 90 to 100 wt % of MMA and 0 to 10 wt % of acrylates having an alkyl radical having 1 to 4 carbon atoms, and wherein the film has a thickness of between 20 and 75 m.

4: The security label according to claim 1, wherein the film is coloured white and for that purpose comprises between 5 and 40 wt % of titanium dioxide.

5: The security label according to claim 1, wherein the polymethacrylate film is produced by an extrusion process wherein a production line used comprises: an extruder, a melt pump, an optional melt filtration facility, an optional static mixing element, a flat film die, a polishing stack or chill roll, and a winder, the flat film die possessing a die lip having actuating elements for adjusting the die lip width, and the actuating elements having a distance of 11 to 15 mm from one another, the die body having an external geometry adapted to the shape of the polishing rolls, and the distance from the melt exit edge to the polishing nip being 80 mm or less.

6: The security label according to claim 5, wherein the flat film die is oriented relative to the polishing stack by means of laser and in that the parallel deviation of the die relative to the polishing rolls, measured at the two ends of one outer side of the die, exhibits a maximum deviation of 3 mm.

7: The security label according to claim 1, wherein the difference between the thinnest and the thickest point of the polymethacrylate film is at most 5 m.

8: The security label according to claim 5, wherein die and roll have chrome surfaces, and in that these chrome surfaces have a roughness Ra of less than 0.08 m.

9: An application-capable security film, which has a thickness of between 15 and 120 m and an elongation at break of between 2.0% and 15%, and wherein the security film before application has at least the following layers in the order stated: a) a polymethacrylate film which comprises 55 to 100 wt % of a polymethacrylate which comprises 80 to 100 wt % of MMA and 0 to 20 wt % of styrene or other (meth)acrylates having an alkyl radical having 1 to 4 carbon atoms, wherein the film comprises at most 10 wt % of an impact modifier, and wherein the security film has printing on at least one side, b) a pressure-sensitive adhesive, c) a release coating, and d) a support layer.

10: The application-capable security film according to claim 9, wherein layer a) has a thickness without printing of between 20 and 75 m, the printing has a thickness of between 1.5 and 3 m, the layer b) has a thickness of between 20 and 30 m, the layer c) has a thickness of between 0.5 and 1.2 m and the layer d) has a thickness of between 20 and 70 m.

11: The application-capable security film according to claim 9, wherein the film is transparent and comprises 90 to 100 wt % of the polymethacrylate.

12: The application-capable security film according to claim 9, wherein the film is coloured white and for that purpose comprises 55 to 95 wt % of polymethacrylate and 5 to 40 wt % of titanium dioxide.

13: The application-capable security film according to claim 9, wherein the film contains no impact modifier.

14: A chip card, document, security label, other label or price tag, comprising the application-capable security film according to claim 9.

Description

EXAMPLES

Example 1

[0059] A moulding composition made up of 98 wt % of a polymethyl methacrylate and 2 wt % of impact modifier, in the form of a core-shell particle, is extruded to a film thickness of 50 m under the following conditions:

[0060] Screw temperature in the extruder: 240 to 270 C.

[0061] Die temperature: 240 to 260 C.

[0062] Temperature of the melt at the die: 240 to 260 C.

[0063] Roll temperature: 50 to 120 C.

[0064] An elongation at break of 3% is measured on the material.

Example 2

[0065] As Example 1, but using 5 wt % of impact modifier. An elongation at break was measured of 4.5%.

Example 3

[0066] Composition: 3

[0067] As Example 1, but using 30 wt % of impact modifier and 20 wt % of titanium dioxide. An elongation at break was measured of 8%.