TRANSLUCENT GASKET COMPRISING A WATERMARK THAT IS NOT VISIBLE IN REFLECTED LIGHT

Abstract

The invention relates to a light-transmitting gasket intended to be positioned on the base of a stopper or cap, in the form of a support having a light-transmitting coating applied to at least one of the surfaces thereof. The gasket is characterised in that the coating contains a watermark, i.e. an image visible in transmitted light, but not visible in reflected light.

Claims

1. A light-transmitting gasket intended in particular to be inserted at the bottom of a stopper or cap, in the form of a support on at least one of the faces of which a light-transmitting coating is applied, characterized in that the coating contains a watermark, that is to say an image visible in transmitted light and not visible in reflection.

2. The gasket according to claim 1, characterized in that the light-transmitting coating comprises a paper sheet and/or at least one polymeric film.

3. The gasket according to claim 1, characterized in that the support is made of a foamed material and is advantageously chosen from the group comprising low density polyethylene (PE), polypropylene (PP), PET, and polystyrene (PS).

4. The gasket according to claim 3, characterized in that a density of the foamed material is between 30 and 500 kg/m.sup.3.

5. The gasket according to claim 3, characterized in that thickness of the foamed material is between 1 and 3 mm.

6. The gasket according to claim 1, characterized in that the support is made of a non-foamed material and is advantageously chosen from the group comprising polyethylene, polyethylene copolymers, thermoplastic elastomers, PP, PET, and PS.

7. The gasket according to claim 6, characterized in that the material has a density between 800 and 1500 kg/m.sup.3.

8. The gasket according to claim 1, characterized in that the support is made of a non-foamed, non-extruded material.

9. The gasket according to claim 8, characterized in that the paper has a density between 40 and 600 kg/m.sup.3.

10. The gasket according to claim 2, characterized in that the polymer film is selected from the group comprising PET, PVDC, polyester, PP, PA, and PE.

11. The gasket according to claim 2, characterized in that the polymeric film is white in color.

12. The gasket according to claim 2, characterized in that the watermark is in the form of a white-colored printing.

13. The gasket according to claim 1, characterized in that the watermark is in the form of a printing applied between the support and the light-transmitting coating.

14. The gasket according to claim 1, characterized in that the watermark is applied to the back of the light-transmitting coating.

15. The gasket according to claim 8, wherein the material comprises paper.

Description

[0020] More precisely, the subject of the invention is a light transmitting gasket, in practice visible light, intended in particular to be inserted at the bottom of a cap or a stopper in the form of a support transmitting itself the light and advantageously made of a foamed material on at least one of the faces on which is applied a material, referred to in the remainder of the description and in the claims by the term coating and also transmitting the light.

[0021] This gasket is characterized in that the face of the support on which the coating is applied, and more precisely the coating itself, has a watermark, that is to say an image visible in transmitted light and not visible in reflection.

[0022] According to the invention, the gasket of the invention is a one-piece gasket or the support part of a double-piece gasket.

[0023] In the case of a one-piece gasket, whether it is the stopper or cap manufacturer or the manufacturer of the final product, who receives the stopper+seal assembly or, more rarely, the seal directly, all of them can perfectly identify the origin of the gasket. In the case of a double-piece seal, the identification of the joint, in practice of its support, can only be carried out after the support has been separated from the lid.

[0024] In fact it is sufficient to place the gasket between the eye and a light source to detect the watermark pattern. The term drawing of course covers any type of marking, whether it is a logo, a name, a drawing, an image, a pattern, etc.

[0025] As already mentioned, the verification can be done directly when the joint is a one-piece gasket. In the case of a two-piece gasket, verification can be carried out after separation of the support and the sealing cap or without prior separation if the seal is not completely opaque.

[0026] According to a first embodiment, the material constituting the support is an foamed material that is preferably chosen from the group comprising low density polyethylene (PE), polypropylene (PP), PET, polystyrene (PS). In practice, the density of the foam is between 30 and 500 kg/m.sup.3, advantageously between 150 and 400 kg/m.sup.3, that is to say an average density.

[0027] According to another characteristic, the thickness of the foam is advantageously between 1 and 3 mm.

[0028] According to a second embodiment, the material constituting the support is a non-foamed material which is preferably chosen from the group comprising polyethylene, polyethylene copolymers, thermoplastic elastomers, PP, PET, PS. In practice, the density of the support is in this case between 800 and 1500 kg/m.sup.3.

[0029] In the two previous embodiments, the support is extruded, in view of the nature of the materials used.

[0030] In another embodiment, the support is made of a non-foamed, non-extruded and light-transparent material. It may be, for example, cardboard with a density advantageously between 40 and 600 kg/m.sup.3.

[0031] According to the invention, the light-transmitting coating applied to the support comprises a paper sheet and/or at least one polymer film.

[0032] In a preferred embodiment, the light transmitting coating comprises at least one polymeric film.

[0033] In practice, the polymeric film is chosen from the group comprising PET, PVDC, PP, polyester, PA (polyamide), PE (polyethylene). The film preferably has a thickness between 5 and 100 micrometers.

[0034] In one particular embodiment, the light transmitting coating comprises two polymer films.

[0035] They can be two coextruded films or two films associated by means of an adhesive. In a particular embodiment, the light transmitting material is a complex consisting of a polyester top film and a polyethylene bottom film.

[0036] The two films once associated are then calendared or laminated onto the support.

[0037] The light transmitting coating is applied to one or both sides of the support that can be extruded or not. When the support, extruded or not, is covered only on one side, the watermark is applied to the face comprising the light-transmitting coating.

[0038] The seal can be positioned at the bottom of the stopper or cap in any direction.

[0039] Of course, the shape of the joints of the invention will be determined as a function of the shape of the stopper or of the cap.

[0040] According to an essential characteristic, the light transmitting coating has a watermark. This watermark can be obtained in various ways, recalling that, by definition, it is a pattern visible in passing light.

[0041] In a preferred embodiment, the light transmitting coating is white in color and the foamed or non-foamed material is advantageously also white in color. At the same time, the watermark is in the form of a white print and is preferably applied to the back of the light transmitting coating. In this case, the coating is advantageously a polymer film.

[0042] Finally and according to another feature, the watermark is applied between the support and the light-transmitting coating, in particular the film. As already stated, the watermark, that is to say an image visible in passing light and not visible in reflection, is preferably applied to the back of the light-transmitting coating.

[0043] The invention and the advantages thereof will become apparent from the description which follows.

[0044] A repeated pattern of white color is printed on a strip of white PET polymer film. The PET film has a thickness of 25 microns.

[0045] This strip of film is laminated on a white foamed PE strip. The foam has a thickness of 1 mm and a density of 200 kg/m3.

[0046] The gaskets of the desired size are cut out in the thickness of the complex obtained.

[0047] If the gasket is placed between the eye and a light source, the watermark is visible between the support and the light transmitting material.

[0048] The invention and the advantages which result therefrom are well apparent from the foregoing description. In particular, it is possible to guarantee the manufacturers of consumer products the origin of the gaskets used in the packaging.