CARDBOARD CONTAINER LAMINATED WITH A RIGID THERMOPLASTIC FILM

Abstract

A food-grade container 1 is described comprising a cardboard container 10 having an opening 11, a bottom 12, side walls 13 that surround the bottom 12 and terminate at the top with a flange 14 that delimits the opening 11 of the container. The container 1 also comprises a thermoplastic film 20 coupled to the container 10 at the bottom 12, the side walls 13 and of the flange 14 by means of heat transfer. The thermoplastic film 20 comprises at least one layer of polyethylene terephthalate (PET) and having a thickness≥150 μm. The basis weight of the cardboard of the container 10 and the thickness of the thermoplastic film 20 are in a ratio from 2:1 to 1:3 (gr/m.sup.2: μm).

Claims

1. A food container (1) comprising: a cardboard container (10) having an opening (11), a bottom (12), side walls (13) which surround the bottom (12) and terminate at the top with a flange (14) that delimits the opening (11) of the container, a thermoplastic film (20), which is coupled to the container (10) at the bottom (12), at the side walls (13) and at the flange (14) by means of heat transfer, said thermoplastic film (20) comprising at least one layer of polyethylene terephthalate (PET) and having a thickness≥150 μm, wherein the basis weight of the cardboard of the container (10) and the thickness of the thermoplastic film (20) are in a ratio from 2:1 to 1:3 (gr/m.sup.2:μm).

2. A container as claimed in claim 1, wherein the basis weight of the cardboard of the container (10) and the thickness of the thermoplastic film (20) are in the ratio 1:1 (gr/m.sup.2:μm).

3. A container as claimed in claim 1, wherein the basis weight of the cardboard of the container (10) ranges from 50 to 450 gr/m.sup.2.

4. A container as claimed in claim 1, wherein the thickness of the thermoplastic film (20) ranges from 150 to 450 μm.

5. A container as claimed in claim 1, wherein the total thickness of the container (1) ranges from 200 to 900 μm.

6. A container as claimed in claim 1, wherein said thermoplastic film comprises at least one layer of amorphous terephthalate polyethylene (A-PET), and a layer of polyethylene terephthalate glycol (PETG).

7. A container as claimed in claim 6 wherein said PETG layer is the layer adjacent to the cardboard container (10).

8. A container as claimed in claim 7 wherein said thermoplastic film further comprises a gas barrier layer that contains ethinyl vinyl alcohol (EVOH) or polystyrene (PS).

9. A container as claimed in claim 7 wherein said thermoplastic film further comprises a heat-resistant layer of polypropylene (PP).

10. A container as claimed in claim 1, wherein the cardboard container (10) is composed of a single blank (100).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] FIG. 1 is a perspective view of the container 1.

[0020] FIG. 2 is a top view of the blank 100.

[0021] FIG. 3 is a top view of the container 1.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] Now, the Applicant has developed a cardboard container, laminated with a rigid plastic film, that can obviate the drawbacks of the prior art.

[0023] In particular, with the container of the invention, the trays have an improved bearing structure, with a flat and stable collar. This provides a consistent distance between the stacked trays, thereby facilitating the use of automatic unstacking systems in the production line.

[0024] The use of a rigid material for lamination of the cardboard container ensures easier peeling of the upper covering film, without causing deformation or delamination of the inner film from the cardboard.

[0025] The present invention relates to a food-grade container 1 comprising a cardboard container 10 having an opening 11, a bottom 12, side walls 13 which surround the bottom 12 and terminate at the top with a flange 14 that delimits the opening 11 of the container. The container 1 also comprises a thermoplastic film 20, which is coupled to the container 10 at the bottom 12, at the side walls 13 and at the flange 14 by means of heat transfer. The thermoplastic film 20 comprises at least one layer of polyethylene terephthalate (PET) and having a thickness 150 μm. The basis weight of the cardboard of the container 10 and the thickness of the thermoplastic film 20 are in a ratio from 2:1 to 1:3 (gr/m.sup.2:μm).

[0026] FIG. 1 schematically shows a perspective view of a food-grade container 1 of the present invention. FIG. 3 depicts a top view of the container 1.

[0027] The container 1 comprises a cardboard container 10 and a rigid thermoplastic film 20.

[0028] The container 10 particularly comprises a bottom 12, side walls 13 which surround the bottom 12 and terminate at the top with a flange 14 that delimits the opening 11 of the container 10.

[0029] The bottom 12 and the side walls 13 have inner surfaces that define an inner surface of the container 10.

[0030] The container 10 is preferably obtained from a blank 100, as schematically shown in FIG. 2.

[0031] More preferably, the container 10 is obtained from a single blank100.

[0032] The blank 100 preferably has folding cutouts 101 at the edges, which assist folding of the cardboard container 10 into a food-grade container 1.

[0033] The container 10 is preferably obtained by folding the blank 100 with adjacent edges of the side walls 13 to form a continuous angular surface.

[0034] The blank from which the container 10 is obtained may be pressed from both sides, so that one pressed side forms the inner surface of the container 10.

[0035] The cardboard that is used for the purposes of the present invention may have any type of cardboard composition that is known in the art to be used for food-grade packaging, and that meets the requirements of the food industry, as well as those imposed for modified-atmosphere packaging.

[0036] Preferably, the cardboard for use in the present invention is a waterproofed cardboard.

[0037] More preferably, the cardboard for use in the formation of the container 10 has a basis weight ranging from 50 to 450 gr/m.sup.2.

[0038] More preferably, the cardboard for use in the formation of the container 10 has a thickness ranging from 200 to 700 μm.

[0039] The thermoplastic film 20 comprises at least one layer of polyethylene terephthalate (PET) and has a thickness 150 μm.

[0040] The advantage of using a thermoplastic film comprising PET is the possibility of obtaining rigid films even with small thicknesses, thereby reducing the plastic part of the container. The rigidity, i.e. the deformation resistance provided by the plastic film, also imparts a structure to the cardboard container, which affords easier handling during production and distribution.

[0041] It shall be noted that, in a preferred embodiment, the thermoplastic film 20 has a thickness that ranges from 150 to 450 μm.

[0042] The thermoplastic film 20 is coupled to the container 10 at the bottom 12, at the side walls 13 and at the flange 14 of such container.

[0043] The thermoplastic film 20 is coupled to the container 10 by means of heat transfer.

[0044] More preferably, the thermoplastic film 20 is coupled by thermal lamination, which is intended as a combination of two or more flat paper, plastic or aluminum materials by adhesion to obtain multilayer structures that combine the properties of each constituent material.

[0045] Thermal lamination (or hot lamination) is carried out using thermoplastic materials that are heated and melted to cause adhesion of two superimposed layers.

[0046] The thermoplastic film 20 is preferably adhesive, with the term adhesive being intended to designate a film which has sealing properties at the heating temperatures of the film, without requiring binding agents for retention or pressure molds for adhesion to the relevant surface.

[0047] In other words, the thermoplastic film 20 is preferably free of binding agents for retention. More preferably the container 1 of the present invention contains no bonding agent (adhesive).

[0048] Still more preferably, the thermoplastic film 20 may be advantageously separated from the cardboard container 10 for recycling purposes.

[0049] In a preferred embodiment, the thermoplastic film 20 is a multilayer plastic film.

[0050] This multilayer plastic film comprises at least one upper layer and one lower layer.

[0051] During lamination, such lower layer faces the inner surface of the container 10.

[0052] In a preferred embodiment, the thermoplastic film 20 comprises at least one layer of amorphous polyethylene terephthalate (A-PET), and one layer of polyethylene terephthalate glycol (PETG). Such PETG layer is preferably the layer adjacent to the cardboard container, i.e. the lower layer.

[0053] The use of PET-G, which is a polymer obtained from copolymerization of PET with ethylene glycol, advantageously allows plastic adhesion to cardboard, without using adhesives.

[0054] Preferably, the thermoplastic film 20 is a single-material multilayer film comprising layers made of PET and/or PET derivatives.

[0055] It shall be noted that, according to a further embodiment, the thermoplastic film 20 comprises a gas barrier layer containing ethinyl vinyl alcohol (EVOH) or polystyrene (PS).

[0056] Preferably, the thermoplastic film comprises a heat-resistant layer of polypropylene (PP)

[0057] The cardboard of the container 10 and the thermoplastic film 20, of the rigid type, are combined to form the container 1 with the basis weight of the cardboard of the container 10 and the thickness of the thermoplastic film 20 in a ratio from 2:1 to 1:3 (gr/m.sup.2 μm).

[0058] Preferably, the cardboard of the container 10 and the thermoplastic film 20, of the rigid type, are combined to form the container 1 with the basis weight of the cardboard of the container 10 and the thickness the thermoplastic film 20 in a 1:1 ratio (gr/m.sup.2 μm).

[0059] It shall be noted that, in a preferred embodiment, the container 1 has an overall thickness that ranges from 200 to 900 μm.

[0060] The bottom 12, the side walls 13 and the flange 14 of the container 10 are preferably maintained in the shape of the container 1 by hot lamination of the thermoplastic film 9 on the inner surface of the container 10.

[0061] The container 1 is suitable for food packaging.

[0062] Once the container 1 has been filled, it may be sealed with a preferably peelable closing plastic film, which allows modified-atmosphere food packaging.

[0063] The composition of the closing plastic film depends on the composition of the thermoplastic film 20 laminated on the container 10.

[0064] The container 1 of the present invention is preferably obtained with the method as disclosed in European patent application no. 3222415, which comprises the steps of:

[0065] providing a cardboard container having an opening, a bottom, side walls which surround the bottom and terminate at the top with a flange that delimits the opening of the container,

[0066] providing a lower shell which is specially shaped to receive the container and has air-passage holes,

[0067] providing an upper shell equipped with heating elements,

[0068] providing a plastic film,

[0069] placing the plastic film between the upper shell and the container placed in the lower shell,

[0070] heating the plastic film by means of the heating elements of the upper shell,

[0071] creating a vacuum between the lower shell and the upper shell to cause the plastic film to adhere to the bottom, the side walls and the flange of the container, wherein the upper shell has a cavity that faces said bottom shell; the step of providing the cardboard container comprises the steps of providing a blank; folding the blank in the lower shell to form the container within the lower shell; and wherein the step of heating said plastic film is carried out by radiation.

[0072] As compared with existing containers composed of plastic and cardboard laminates, the container 1 of the invention provides the following benefits:

[0073] Improved peeling between the tray and the top film: the use of a rigid film for hot lamination of the cardboard facilitates separation of the plastic portion from the paper portion, also due to the lack of adhesive materials.

[0074] Unstacking of containers: the containers of the invention are sufficiently rigid to withstand the unstacking forces of automatic tray separation systems in the production lines without deformation.

[0075] Container recycling: the container 10 and the thermoplastic film 20 may be easily separated and recycled separately with paper and plastic, respectively. The use of a single-material thermoplastic film allows recycling of the plastic part of the container, unlike composite films, such as PET+PE, in which the PE component coupled with the PET “pollutes” material, and does not allow easy recycling thereof.

[0076] Therefore, the use of a cardboard container laminated with the thermoplastic film allows the thickness of the film to be reduced even to 50% as compared with an all-plastic tray.

EXAMPLES

[0077] Exemplary embodiments of the food-grade container of the present invention are described below by way illustration only and without limitation.

TABLE-US-00001 TABLE 1 Representative Aspects of Food-Grade Containers Thickness of an all- Container of the invention plastic container Thickness of the Basis weight of Height of the having the same thermoplastic cardboard of the container (1) height film (20) container (10) (mm) μm (μm) (gr/m.sup.2) H10 300 150 150 H20 300 150 150 H30 400 200 200 H40 500 250 250 H50 500 250 250 H60 600 300 300 H70 700 350 350

[0078] Many other benefits will no doubt become apparent from future application and development of this technology.

[0079] All patents, applications, standards, and articles noted herein are hereby incorporated by reference in their entirety.

[0080] The present subject matter includes all operable combinations of features and aspects described herein. Thus, for example if one feature is described in association with an embodiment and another feature is described in association with another embodiment, it will be understood that the present subject matter includes embodiments having a combination of these features.

[0081] As described hereinabove, the present subject matter solves many problems associated with previous strategies, systems and/or devices. However, it will be appreciated that various changes in the details, materials and arrangements of components, which have been herein described and illustrated in order to explain the nature of the present subject matter, may be made by those skilled in the art without departing from the principle and scope of the claimed subject matter, as expressed in the appended claims.