FR2714891A1 - Rigid food packaging dish with integral hinged lid - Google Patents

Abstract

A dish having a rigid base (4) and hinged lid (5) is made from a plastic sheet made of rigid plastic film (2) and a flexible plastic film (1), bonded together or coextruded; formed into the base and the lid arced between them the rigid film is cut, without cutting the flexible film, which then forms the hinge (6). The rigid film material is PVC and the flexible film material is polyethylene. A film sealing film is placed over the dish prior to closing the lid. The length of the hinge is less than the length of the dish.

Description

METHOD FOR MANUFACTURING A TRAY HAVING
A RIGID AND ARTICULATED BACKGROUND AND COVER, ONE ON
THE OTHER AND TRAY OBTAINED BY THIS PROCESS
The present invention relates generally to packaging intended to contain food, and more particularly plastic trays.

 I1 is known to use trays obtained by thermoforming for the marketing of food, for example prepared meals.

 The trays usually used are of two types, some are made of a material flexible enough to be able to present a movable cover in rotation around a hinge relative to a bottom containing the food, while others are made of a more rigid material and are closed by a sealing seal welded to the periphery of their upper opening.

 These two types of trays, although very widespread each have drawbacks: the trays made of flexible material are not strong enough to withstand the manipulations to which they are subjected during their marketing, and the trays of rigid material suitably support the manipulations but it is not possible to close them if you do not consume the food they contain at once.

 The present invention aims to provide a method of manufacturing a tray made of a rigid material having a cover movable in rotation relative to the bottom around a hinge.

 To this end, the method of manufacturing a rigid tray having an adjoining cover is characterized in that a hinge is formed by cutting the rigid film constituting the manufacturing material in line with the articulation line.

 The invention also relates to the tray obtained by this manufacturing process.

The invention will be better understood from the description which follows given by way of nonlimiting example with reference to the accompanying drawings in which
FIG. 1 is a sectional view of a material used for the manufacture of a tray according to the invention,
FIG. 2 is a sectional view of the sheet of material after thermoforming,
- Figure 3 is an enlarged view of the noted detail
III in FIG. 2,
FIG. 4 is a sectional view of a tray produced by the method according to the invention,
FIG. 5 is an enlarged view of the detail denoted V in FIG. 4,
- Figure 6 is a top view of a tray produced by the method of the invention with its cover open.

 The material used for the production of a rigid tray is a sheet material comprising several constituents, some are rigid in order to ensure the mechanical strength of the finished product, the others are flexible and seal the trays at the same time as they allow sealing by sealing of a sealing cap.

 Usually, the rigid component is a polyvinyl chloride film and the flexible component is a polyethylene film.

 Sheet materials composed of several constituents can be obtained by various known methods such as laminating extruded films, coextrusion or laminating the films.

 The material represented in FIG. 1 is a material obtained by this latter process, it is formed of a flexible film of polyethylene 1 and of a rigid film of polyvinyl chloride 2 joined together by a binder 3.

 The rigid film is usually thicker than the flexible film.

 The first step in manufacturing the trays is a step of thermoforming the sheet material. During this step, we form as shown diagrammatically in FIG. 2, imprints 4 and 5 separated from each other by bridges 44, 45 of material. This thermoforming step is carried out by positioning the material in such a way that the polyethylene film is on the internal face of the impressions. These imprints are regularly distributed both transversely and longitudinally over the surface of the sheet, they can be of any desired shape and size.

 Usually, these imprints are intended to constitute bottoms 4 of trays and covers 5.

 The food is positioned in each bottom 4, then a cover is sealed on the flat upper portions of the bridges, 44, 45 by welding with the polyethylene film.

 The choice of imprints 4 arranged side by side makes it possible to manipulate only a cover 7 covering the two rows of bottoms. Said cover covers, of course, all of the imprints arranged one beside the other along the direction perpendicular to the plane of the drawing.

 This cover is welded to the polyethylene film present on the upper face of bridges 44 and 45.

 According to the invention, the film of rigid material is cut along the center line of the bridges 45 as shown in FIG. 3. A notch 20 is cut in said rigid film 2 made of polyvinyl chloride, taking care not to tear the flexible film 1 of polyethylene.

This notch may not relate to the entire thickness of said rigid film 2.

 The rows of fingerprints 4 are separated from one another by cutting the bridge 44 along its center line.

Unlike notch 20, this cut is made throughout the thickness of the sheet material.

 There are also separate assemblies formed from a bottom 4 and a cover 5, from each other, along bridges not shown in the drawing and perpendicular to bridges 44 and 45.

 The imprint 5 forming a cover can then, thanks to the invention, be folded down relative to the imprint or bottom 4 as shown in FIG. 4 so as to close said bottom. Indeed, the notch 20 relating only to the rigid film 2 of polyvinyl chloride, the flexible film 1 fulfills the role of a hinge 6 between the two parts of the tray, while ensuring the tightness of said tray.

 The shapes of the imprints 4 and 5 produced in the sheet material during thermoforming are of course such that the cover 5 can be secured by snapping onto the bottom 4.

 The latching means can be produced at the time of thermoforming of the sheet material or subsequently using a hot blade.

 FIG. 6 represents an advantageous form of tray which can be produced by the method according to the invention.

 As can be seen, the bridge 45 separating the bottom 4 of the cover 5 is provided with a length much less than the length of the tray.

 After the impressions necessary for the production of the bottom 4 and the cover 5 are thermoformed, the bridge 45 separating them is folded so as to form the returns 64 and 65, then the latching means 8 are formed around the periphery of the cover 5, the bridge 45 apart.

 These returns 64 and 65 make it possible, as visible in FIG. 4, to ensure that the part of the tray having the hinge remains in the same size as the rest of the periphery of said tray.

 In addition, thanks to the fact that the hinge 6 is thus offset downward relative to the periphery of the bottom 4, the installation of the latching means is done easily, starting with the side of the bottom located opposite the cover. , on either side of the bridge with the hinge.

 In fact, said latching means 8 are placed automatically under the periphery of the bottom 4 during the rotation of said cover around the hinge 6.

 I1 only remains to apply pressure on the short sides and on the face opposite to the hinge 6 to complete the fixing of the cover to the bottom 4.

 When using the tray, the buyer opens the latter by pivoting the cover 5 around the hinge 6 formed by the invention, he removes the cover 7 and takes out the food he wishes to consume. I1 can then close the tray by bringing the cover 5 back into its bottom closed position 4.

 Although the above description and the drawings have taken into account a composite material in sheet form comprising a layer of binder joining the flexible film and the rigid film, it is understood that a material composed of any other composition and / or obtained by any other method can be implemented.

 Advantageously, in the case of a material obtained by bonding the rigid film and the flexible film, it is possible to take care not to deposit a binder on a strip disposed on either side of the center line of the bridge intended to form a hinge 6.

Claims (6)

 1. - Method for manufacturing a tray having a bottom (4) and a cover (5) rigid and articulated one on the other by means of a flexible hinge (6), of the type in which  a sheet of plastic material is made from a film of rigid plastic material and a film of flexible plastic material, assembled by gluing or coextrusion,  said sheet is shaped to constitute the bottom and the cover of the tray,  characterized in that between the bottom (4) and the cover (5), the rigid film is cut without the flexible film being cut, so that the flexible film constitutes the hinge.  2. - Method according to claim 1, characterized in that in the case where the rigid film and the flexible film are assembled by bonding, the bonding binder is not applied to the right of the hinge.  3. - Tray characterized in that it is manufactured by the method according to one of claims 1 or 2.  4. - Tray according to claim 3, characterized in that after filling and before closing by the cover, the bottom is provided with a sealing cap (7).  5. - Tray according to claim 4, characterized in that after removal of the sealing cap, the tray is reusable.  6. - Tray according to any one of claims 3 to 5, characterized in that the bridge (45) separating the bottom (4) of the cover (5) is of a length less than the length of the tray.