EP1275100B1 - Self-adhesive display film - Google Patents

Abstract

Auto-adhesive display film comprising at least one electrically charged, dielectric layer (2). A screen layer (3), which is adapted to form a barrier to the electric field, is fixed to one surface of the dielectric layer (2). This display support does not attract dust particles and is specifically adapted to be printed sheet by sheet.

Description

The present invention relates to display films self-adhesive comprising at least one loaded layer electrically, which are suitable for adhering automatically on most smooth surfaces such as windows, walls, paintings or the like.

Among these display films, the invention relates to especially those that include at least one first dielectric layer, said layer comprising a part, a first side, and secondly, a second side electrically charged.

Display films of this kind, which are known at present, usually include a layer that is made of polymer, preferably polypropylene. Due to the electrostatic force generated by the presence of electrical charges that are contained in inside this layer it is possible to do instantly adhere to the display movies on most smooth surfaces.

These display films nonetheless present the following disadvantage: the face of the support layer which is not in contact with the smooth surface tends to attract the various particles contained in the air ambient, such as for example dust, smoke, etc. Therefore, the visual aspect of these supports degrade quickly. Moreover, these various particles can be ionized or carrying electric charges, which has effect of reducing the electrostatic force that makes adhere the display medium to said smooth surface.

The present invention is intended in particular to remedy these disadvantages.

For this purpose, the display films of the kind in question are characterized in that a first screen layer, which is adapted to barrier the electric field, is fixed on at least said first face of the first dielectric layer, and this the first screen layer (3) consists of a material which has a conductivity value of at least 10 ^-10 S / cm.

• le matériau de la première couche diélectrique est choisi parmi le polypropylène et le polyéthylène téréphtalate ;
• le matériau de la première couche diélectrique est un polymère comprenant au moins un atome de fluor par monomère ;
• le polymère est choisi parmi le polytetrafluoroethylène et le polyfluoroethylènepropylène ;
• le matériau de la première couche écran est un métal ;
• le matériau de la première couche écran comprend au moins un oxyde métallique transparent et conducteur ;
• la première couche diélectrique et la première couche écran sont transparentes ;
• la première couche écran est fixée de façon définitive sur la première couche diélectrique ;
• une feuille de recouvrement est fixée de manière amovible sur la seconde face de ladite première couche diélectrique, cette feuille de recouvrement comprenant au moins une deuxième couche écran ; ceci est avantageux dans le sens où le support d'affichage peut être conditionné en rame et être utilisé feuille à feuille dans une presse ou une imprimante, sans collage entre les supports empilés, ce qui n'est pas le cas des supports d'affichage auto-adhésifs connus ;
• la deuxième couche écran est sensiblement identique à la première couche écran ;
• la feuille de recouvrement comprend au moins une deuxième couche diélectrique qui est fixée à la deuxième couche écran et interposée entre cette deuxième couche écran et la première couche diélectrique ;
• le matériau de la deuxième couche diélectrique est un polymère ;
• les première et deuxième couches diélectriques sont constituées du même matériau ;
• les première et deuxième couches diélectriques ont sensiblement la même épaisseur ;
• la deuxième couche écran est fixée de manière définitive sur la deuxième couche diélectrique ;
• la première couche écran est continue.

In preferred embodiments of the invention, one or more of the following may also be used:

• the material of the first dielectric layer is selected from polypropylene and polyethylene terephthalate;
• the material of the first dielectric layer is a polymer comprising at least one fluorine atom per monomer;
• the polymer is selected from polytetrafluoroethylene and polyfluoroethylenepropylene;
• the material of the first screen layer is a metal;
• the material of the first screen layer comprises at least one transparent and conductive metal oxide;
• the first dielectric layer and the first screen layer are transparent;
• the first screen layer is permanently attached to the first dielectric layer;
• a cover sheet is releasably attached to the second face of said first dielectric layer, said cover sheet comprising at least a second screen layer; this is advantageous in the sense that the display medium can be packaged and used sheet-by-sheet in a press or printer, without gluing between the stacked supports, which is not the case of the display media self-adhesive known;
• the second screen layer is substantially identical to the first screen layer;
• the cover sheet comprises at least one second dielectric layer which is fixed to the second screen layer and interposed between this second screen layer and the first dielectric layer;
• the material of the second dielectric layer is a polymer;
• the first and second dielectric layers are made of the same material;
• the first and second dielectric layers have substantially the same thickness;
• the second screen layer is permanently fixed on the second dielectric layer;
• the first screen layer is continuous.

Other features and benefits of the present invention will emerge during the description which will follow of several of its embodiments, given by way of non-limiting examples, with reference to to the attached drawings.

• la figure 1 montre une vue en coupe verticale d'un exemple du film d'affichage selon l'invention, avant son adhésion sur une surface lisse,
• et la figure 2 est une vue similaire à la figure 1, pour une variante de l'invention.

On the drawings:

• FIG. 1 shows a vertical sectional view of an example of the display film according to the invention, before its adhesion on a smooth surface,
• and FIG. 2 is a view similar to FIG. 1 for a variant of the invention.

• une première couche diélectrique 2 chargée électriquement ;
• une première couche écran 3, qui est constituée d'un matériau conducteur de l'électricité, ladite couche étant fixée de manière permanente sur une première face de la couche 2 ;
• une deuxième couche diélectrique 4 qui est constituée d'un matériau électriquement isolant, ladite couche 4 étant fixée de manière amovible sur une seconde face de la couche 2 qui est opposée à ladite première face ;
• et une deuxième couche écran 5 qui est constituée d'un matériau conducteur de l'électricité, ladite couche étant fixée de manière permanente sur la face de la couche 4 qui n'est pas en contact avec la couche 2.

The display film 1 as illustrated in FIG. 1 is, before use, in the form of a multilayer structure comprising at least:

• a first electrically charged dielectric layer 2;
• a first screen layer 3, which is made of an electrically conductive material, said layer being fixed permanently on a first face of the layer 2;
• a second dielectric layer 4 which is made of an electrically insulating material, said layer 4 being removably attached to a second face of the layer 2 which is opposite said first face;
• and a second screen layer 5 which is made of an electrically conductive material, said layer being fixed permanently on the face of the layer 4 which is not in contact with the layer 2.

Layers 2 and 3 form a self-adhesive film 6 adapted to adhere automatically to smooth surfaces, while layers 4 and 5 form a sheet protective cover 7 removable.

The material of the dielectric layer 2 is a plastic material, preferably polypropylene, which presents the property of preserving particularly well the electric charges. Other materials can also be used, such as for example polyethylene terephthalate (in particular sold under the trademark Mylar by Du Pont de Nemours), polytetrafluoroethylene and polyfluoroéthylènepropylène.

Layer 2 has a thickness whose value is, for example, between 1 and 100 μm.

The material of layer 3 preferably has a minimum conductivity value of 10 ^-10 S / cm. It is particularly adapted to barrier the electrostatic field due to the electrical charges contained in the layer 2.

The material chosen for layer 3 is conductive preference, transparent or not. It could be metal, especially aluminum, but can also be consisting of a conductive polymer, a metal oxide transparent and conductive, a conductive ink, or others.

Layer 3 has a thickness whose value is, for example, between 10Å and 10 μm.

The layer 3 is fixed on the layer 2 for example by bonding, by vacuum deposition metallization, by coextrusion, a conductive lacquer or others.

The visible side of layer 3 is intended to be printed by a conventional printing process, for example offset type, silk screen, digital, laser, jet ink, typographic, heliographic, or others.

The visible face of the layer 3 may, prior to this impression, receive a specific treatment intended to favor the maintenance of inks, for example by ionic or electronic bombardment, or by deposit or coating of an underlayer hooking.

According to a particularly advantageous variant, a additional layer 8 that can be printed (Figure 2) can be fixed on the visible side of the layer screen 3, in which case it is this extra layer and not the layer 3 that is printed. This extra layer consists of a flexible material with characteristics favorable to printing, especially in terms of visual appearance, color, opacity, grain, etc. .... material may be, for example, ink, paper, polyester, polyethylene, polypropylene, or the like.

In this case, it may be advantageous for a small part 9 of layer 3 is not covered by the said additional layer 8, in order to allow the establishment an electrical contact on this part.

Layer 8 could also be a layer of material on which one can write by means of a felt erasable, the writing thus made on layer 8 being erasable by simply wiping dry.

In the two variants described above, the material used for layer 4 is a plastic any, for example polypropylene, polyethylene terephthalate (in particular sold under the trademark Mylar Pont de Nemours), polyester, PVC or polyethylene.

In order to obtain optimum preservation of the loads electrical devices inside layer 2, layer 4 is preferably made of the same material as that of the layer 2 and advantageously has a thickness substantially identical to that of layer 2.

Layer 5, on the other hand, consists of a electrically conductive material, for example the same than that of the screen layer 3.

The layer 4 and the layer 5 can be fixed one to each other respectively in the same way as layer 2 and layer 3.

During the manufacture of the display medium, electrical charges are deposited in the material and on the face of layer 2 which is intended to come into contact with layer 4. These charges are deposited by a process classic, such as for example the Corona effect, the ion bombardment or electron bombardment. of the means are then provided so that during this operation, layer 3 can be electrically connected to a potential predetermined, for example that of the earth.

Once this operation is completed, we obtain a self-adhesive film 6 which has the power property spontaneously adhere to any type of flat surface, by the face of its layer 2 which is not in contact with the layer 3, thanks to the action of the force of attraction electrostatic created by the presence of charges electric.

This support also presents the possibility of being taken off in order to be repositioned, for example on a other flat surface.

After this electrostatic charging operation, the display medium according to the invention is covered temporarily by the protective sheet 7 which is consisting of all layers 4 and 5.

Due to the constitution of the layer electrically insulating 4, the protective sheet 7 adheres spontaneously on layer 2. Layers 2 and 4 are then held together by the force of attraction electrostatic generated by the presence of charges in layer 2, the latter do not able to escape from the display medium thanks to the good insulating and material retention properties of the material two layers 2 and 4.

Such an arrangement of the layers 3 and 5 has for advantage of canceling the external electric field which without they, would be created by the electrical charges present in layer 2. We can therefore manipulate the support before it is printed and / or used, without risk of observing a degradation of the support which would result of the attraction of various particles, such as in particular dust, on the dielectric layer 2.

Moreover, given the constitution of the layers 3 and 5, the display medium according to the invention can be conditioned in reams. This one can therefore without problem be sheet-fed in a press or printer, the various supports that constitute a train that does not risk not to stick to each other at the time of the impression.

According to one variant, the layer 4 is itself electrically charged with a charge opposite to that of the layer 2. Thus, the self-adhesive film 6 and the set consisting of layers 4 and 5 may be used separately as self-adhesive display films.

In this case, it is also possible to interpose, between the self-adhesive film 6 and the set consisting of layers 4 and 5, another film similar to layers 2 and 4.

During the storage of trains, means may be be provided for electrically connecting layers 3 and 5 between them, which has the effect of improving the retention electrical charges in layer 2 and to facilitate the cancellation of the external electrostatic field.

The self-adhesive film 6 can then be applied by its layer 2 on any smooth surface, after removing the protective sheet 7.

According to a particularly advantageous variant (Figure 1), the material chosen for layer 2 is a transparent material such as for example polypropylene, and the layer 3 is itself made of a material transparent and conductive such as a metal oxide transparent, for example an indium and / or tin oxide, polyaniline, or a compound of polyaniline and polymetracrilate, or a compound of polyaniline and polycarbonate, so as to be able to display and view the display medium on and at through a transparent surface (glass) on which would affixed the dielectric layer 2 of the film 6.

According to another advantageous variant, the self-adhesive film 6 and the protective sheet 7 are bonded together by one of their edges. This link facilitates the passage of display film according to the invention in certain machines printing with rollers for example. So, the self-adhesive film 6 and the protective sheet 7 do not risk not to shift when passing between rollers, if the edge on which they are linked goes first between these rollers. This connection can be made by heat-sealing over a width of about 1.5 cm. In that case, this band is advantageously cut after printing the self-adhesive film 6.

According to a variant, this connection can be ensured by a sticky tape or any other means of this type.

According to another variant, the display medium could possibly be constituted by the self-adhesive film 6 alone, without the protective sheet 7, in which case the layer 3 already avoids in itself the accumulation of dust on the printed side of the display medium.

Claims (17)

1. An auto-adhesive display film adapted to automatically adhere to smooth surfaces comprising at least one first dielectric layer (2), said layer comprising, on the one hand, a first surface, and, on the other hand, a second surface which is electrically charged,
   characterised in that a first screen layer (3), adapted to form a barrier to the electric field, is fixed to at least, said first surface of the first dielectric layer (2),
   and in that the first screen layer (3) is constituted of a material with a conductivity equal to at least 10^-10 S/cm.
2. Display film according to claim 1, wherein the material constituting the first dielectric layer (2) is selected from polypropylene and polyethylene terephtalate.
3. Display film according to claim 1, wherein the material constituting the first dielectric layer (2) is a polymer comprising at least one atom of fluorine per monomer.
4. Display film according to claim 3, wherein the polymer is selected from polytetrafluoroethylene and polyfluoroethylenepropylene.
5. Display film according to any of the preceding claims, wherein the material constituting the first layer (3) is a metal.
6. Display film according to any of the preceding claims, wherein the material constituting the first layer (3) comprises at least one transparent and conductive metallic oxide.
7. Display film according to any of the preceding claims 1 to 5, wherein the material of the first screen layer is selected from a polyaniline, a composite of polyaniline and methyl polymetacrilate, and a composite of polyaniline and polycarbonate.
8. Display film according to any of the preceding claims, wherein the first dielectric layer (2) and the first screen layer (3) are transparent.
9. Display film according to any of the preceding claims wherein the first screen layer (3) is permanently fixed to the first dielectric layer (2).
10. Display film according to any of the preceding claims, wherein a removable cover foil (7) is fixed to the second surface of said first dielectric layer (2), this cover foil comprising at least one second screen layer (5).
11. Display film according to claim 10, wherein the second screen layer (5) is substantially identical to the first screen layer (3).
12. Display film according to claim 9 or 10, wherein the cover foil (7) comprises at least a second dielectric layer (4) which is fixed to the second screen layer (5) and placed between this second screen layer and the first dielectric layer (2).
13. Display film according to claim 12, wherein the material constituting the second dielectric layer (4) is a polymer.
14. Display film according to claims 12 to 13, wherein first (2) and second (4) dielectric layers are constituted of the same material.
15. Display film according to any of the claims 12 to 14, wherein the first (2) and second (4) dielectric layers have exactly the same thickness.
16. Display film according to any of the claims 12 to 15, wherein the second screen layer (5) is permanently fixed to the second dielectric layer (4).
17. Display film according to any of the preceding claims, wherein the first screen layer (3) is continuous.

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