TECHNICAL FIELD The present description relates to a bag which can be employed for food use, in particular a bag which can be reclosed after it has been opened.

BACKGROUND OF THE DESCRIPTION A known laminated material is provided with two layers of plastic material joined by a pressure adhesive also known as PSA (Pressure-Sensitive Adhesive), which adhesive allows the separation of a tongue obtained by incising one of the two layers. Such laminated material can be used to close a food container.

WO 2015/145338 Al describes a tray which is closed by a sheet of such laminated material and can be opened and then reclosed by manually lifting an outer portion of the outer layer or first layer which is not joined by adhesives to the inner layer or second layer, or manually lifting an outer portion of both layers thanks to a special incision made in the second layer near the edge welded to the tray.

However, precisely because it is easy to open and close, this known container can also be easily tampered with to illegally remove the contents or part of it, so that it requires a special anti-tamper seal, with consequent negative aesthetic and economic effects.

To overcome this drawback, US 2017/0057728 Al and US 8541081 describe trays, receptacles or other rigid containers which are closed by a film which can be pulled from an outer flap, so as to create a tear in it which acts as an anti-tamper seal.

Such known containers, due to the rigid container, have a relatively high manufacturing cost and are relatively difficult to produce.

SUMMARY OF THE DESCRIPTION The object of the present description is therefore to provide a container free from such drawbacks. Said object is achieved with a bag, the main characteristics of which are specified in the attached claims.

Thanks to its particular multilayer structure, the bag according to the present description can be manufactured simply, quickly and inexpensively, it is easy to open and close and is however sealed with an anti-tamper device.

The capacity of the bag can be increased by a bellows formed in the sheet of the side opposite to the opening of the bag, so that the bellows also acts as a base for keeping the bag in an upright position.

According to a particular aspect of the present description, the first layer, the second layer and/or the adhesive layer are uniform and/or continuous, with the exception of the preferably single incision in the second layer, so as to manufacture in a simple and economical way a continuous laminate material, aesthetically valuable as it is free of discontinuities (except the incision), which can be easily cut into different sizes to manufacture the bag.

In particular, the incision in the bag is obtained by means of a mechanical die-cutter, so as to be able to use substantially transparent layers which allow the vision of a product through the resulting laminated material.

BRIEF DESCRIPTION OF THE DRAWINGS Further advantages and characteristics of the bag according to the present description will be clear to those skilled in the art from the following detailed and non- limiting description of an embodiment thereof with reference to the attached drawings in which:

- Figure 1 shows a top view of the bag;

- Figure 2 shows a bottom view of the bag of Figure 1;

- Figure 3 shows a vertical section view of the bag of Figure 1;

- Figure 4 shows the enlarged section IV-IV of Figure 3;

- Figure 5 shows the bag of Figure 4 during its opening.

EXEMPLARY EMBODIMENTS With reference to Figures 1 to 4, it is seen that the bag according to an embodiment of the present description comprises at least one first layer 1 or outer layer, which is suitable to be facing the outside of the bag. The first layer 1 is preferably free of cuts or openings and is joined to at least one second layer 2 or inner layer, suitable to be facing the contents of the bag, by at least one adhesive layer 3 arranged between the layers 1, 2, preferably in a uniform manner, particularly in a substantially complete manner, namely with the adhesive layer 3 which covers in a substantially complete manner the first layer 1 and/or the second layer 2, thus forming a sheet of laminated material, preferably continuous to be wound up a roll. The first layer 1 and/or the second layer 2 preferably comprise at least one film of plastic material, while the adhesive 3 is preferably a pressure adhesive which allows both the separation of the first layer 1 from the second layer 2 by manual traction and their subsequent adhesion by pressing the first layer 1 on the second layer 2, and/or vice versa. Preferably, the first layer 1, the second layer 2 and the adhesive 3 are substantially transparent, so that the resulting laminated material is substantially transparent.

The second layer 2 is made of a material capable of be cut if subjected to a shear stress, preferably without substantially elongating or deforming, and is preferably suitable to be heat welded. Said material comprises in particular polyethylene, polypropylene cast or another polyolefin and/or has a thickness of between 15 and 100 microns, preferably between 15 and 50 microns. The thicknesses shown in Figure 4 have been enlarged for reasons of clarity.

An incision 4 preferably in the shape of a tongue, in particular U-shaped or V- shaped, is formed in the second layer 2, so as to form in the second layer 2 a tongue- shaped portion 2a which can be separated from a remaining portion 2b of the second layer 2 and remain joined to the first layer 1 by means of the adhesive 3. At least one end of the incision 4 is preferably provided with a curl 5 to prevent a tear of the second layer 2 and/or a detachment thereof from the first layer 1 at this curl 5. The second layer 2 may have other incisions but it is preferable that it has no other incisions besides the incision 4.

The second layer 2 is joined, in particular welded, to at least one sheet 6, in particular a sheet comprising one or more layers of plastic material laminated with each other, in which at least one surface of the sheet 6 is suitable to be joined, preferably heat- welded, to the second layer 2. The width and/or the length of the first layer 1 are substantially equal to the width and/or the length, respectively, of the second layer 2 and/or of the sheet 6. The sheet 6 may be provided with a bellows 7 to form a bag with a larger cavity together with the layers 1, 2. The portion 2c of the second layer 2 joined to the sheet 6 at least partially surrounds the incision 4, in particular forming a perimetrical frame that delimits a cavity between the second layer 2 and the sheet 6. At least one portion 2d of the second layer 2 is arranged outside the portion 2c joined to the sheet 6, namely on the opposite side with respect to the portions 2a and 2b which are inside the portion 2c, as shown in Figure 3. In this way the outer portion 2d can be gripped by two fingers by a user, together with the portion of the first layer 1 joined to this outer portion 2d, so as to manually separate the second layer 2 from the sheet 6. Also the outer portion 2d of the second layer 2 is preferably joined to the first layer 1 by an adhesive layer, in particular by the adhesive layer 3. In the present embodiment, the outer portion 2d of the second layer 2 is arranged on the side opposite to the bellows 7 of the sheet 6.

Figure 5 shows the outer portion 2d of the second layer 2 pulled manually in the direction of the arrow S by the user together with the corresponding portion of the first layer 1, so that the outer portion 2d of the second layer 2 is separated from the portion 2c joined to the sheet 6, thus creating at least one cut 8 between these two portions 2c, 2d of the second layer 2. The cut 8 starts from an edge of the second layer 2 and follows the edge of the portion 2c adjacent to the outer portion 2d. The outer portion 2d of the second layer 2 is then separated by the cut 8 from the portion 2c joined to the sheet 6 and from the remaining portions 2a, 2b of the second layer 2. The tongue- shaped portion 2a of the second layer 2 is raised due to the lifting of the first layer 1 joined thereto by the adhesive layer 3, while the remaining portion 2b of the second layer 2 is kept joined to the sheet 6 by the portion 2c joined thereto. The outer portion 2d of the second layer 2 is arranged on at least one corner of the bag and preferably has a rectangular, triangular or arcuate shape, or a combination thereof. For example, the outer portion 2d shown in Figure 3 has a combination of a rectangular shape and a triangular shape, in which the triangular portion corresponds to a corner of the layers 1 and 2.

In the manufacture of the bag, the first layer 1 provided with adhesive 3 is joined to the second layer 2 by auxiliary rollers, so as to obtain a laminated material. Before being wound on a roller, at least one mechanical die-cutter, in particular a roller die-cutter, forms the incision 4 in the second layer 2. In an alternative embodiment, the incision 4 can be formed in the second layer 2 before joining the first layer 1 to the second layer 2.

In a subsequent step, this laminated material is joined to a sheet by adhesive or preferably heat-sealing and then cut to obtain the bag, wherein the second layer 2 is joined to the sheet 6. In another embodiment, the second layer 2 can be joined first to the sheet 6 and then to the first layer 1.

One or more further incisions, in particular a series of incisions (not shown in the figures) arranged along at least one straight or curvilinear trajectory, so as to form a dashed line, may be made in the outer portion 2d of the second layer 2, so as to favor the cut 8 between the outer portion 2d and the remaining portion of the second layer 2.

Possible variants or additions may be made by those skilled in the art to the embodiments described and illustrated herein while remaining within the scope of the following claims. In particular, further embodiments may include the technical features of one of the following claims with the addition of one or more technical features described in the text or illustrated in the drawings, taken singularly or in any mutual combination.