Container, sheet material and joining element for such container, and machine and methods for manufacturing them

Abstract

A container has a perimeter wall (3) having a sheet material (51) having a support means (52), the perimeter wall (3) defining an internal volume (4) of the container and being welded by electromagnetic induction at a welding portion (55) of the support means (52) provided with a joining element (57) for induction welding. Regarding the joining element (57) adjacent to the internal volume (4) of the container (1), a first adhesive layer (71) and a second adhesive layer (72) on each side of a conductive layer (59) of the joining element (57) are mutually connected at a portion of the perimeter edge (63) of the conductive layer (59) adjacent to the internal volume (4), insulating the conductive layer (59) from the internal volume (4), thereby avoiding any contact with the food which may be contained therein.

Description

[0001] IMPROVED CONTAINER, SHEET MATERIAL AND JOINING ELEMENT FOR SUCH CONTAINER, AND MACHINE AND METHODS FOR MANUFACTURING THEM

[0002] DESCRIPTION OF THE INVENTION

[0003] The present invention relates to the field of containers production, particularly food cartons for food or beverages, and more specifically concerns an improved container, a sheet material, and a joining element for manufacturing such container, and methods and a machine for manufacturing such container and sheet material.

[0004] A container for food or beverages is known consisting of a perimeter wall made from a sheet material of the so-called multilayer type, defining an internal volume of the container intended to hold the food or beverage. The perimeter wall is typically welded with a hot air jet or induction weld, or is glued longitudinally into a tubular shape, and is welded transversely by electromagnetic induction at its welded portions at the bottom and top ends, these welded portions bearing joining elements. Each joining element, typically a strip or patch, comprises a laminar conductive layer sandwiched between two adjacent heat-sealing layers: heating the conductive layer causes the heatsealing layers to melt, bonding them to the perimeter wall on each side of the conductive layer, achieving welding of the perimeter wall to the conductive layer and thus closing one end of the container. Once the weld is complete, the edge of the conductive layer of the joining elements remains uncovered by the heat-sealing layers and in contact with the internal volume of the container and its contents.

[0005] A disadvantage of the known container is that the conductive layer of the joining elements comes into contact with the food or beverage inside the container. The container material can therefore be deteriorated by the food or beverage, particularly if acidic, and degrade, increasing the risk of weld failure and reducing the container's service life and, therefore, the shelf life of the product contained within.

[0006] Another disadvantage of the conventional container is that the conductive layer of the joining elements, corroded by the food or beverage, can release substances or particles into the food or beverage, altering the organoleptic properties of the food or beverage and potentially posing a risk of intoxication or poisoning for a consumer of the food or beverage.

[0007] An additional disadvantage is that the heating is typically concentrated in a central portion of the conductive layer, and consequently, the weld is strongest only in a small portion of the respective welding portion.

[0008] Another disadvantage of the known container is that its production cycle is intermittent, requiring a temporary stop, however short, for each application of a joining element.

[0009] One object of the present invention is to propose an improved container in which the two heat-sealing layers of each joining element are welded or joined together in a single body at least along the edge of the joining element adjacent to the internal volume, thus separating the conductive layer from the internal volume and the food or beverage.

[0010] Another object of the present invention is to propose a safe and durable container in which the welds are not affected by the food or beverage contained therein and do not release substances or particles of conductive material into the latter.

[0011] A further object of the present invention is to propose a sheet material for the manufacturing of the improved container, in which at least one of the heat-sealing layers comprises an abundance of heat-sealing material connected or suitable for welding to the opposite heat-sealing layer to insulate the edge of the conductive layer from the internal volume of the container that will be formed from the sheet material. Another object of the present invention is to propose a method for manufacturing the improved container starting from such sheet material, wherein during welding each welding portion is also compressed from the outside to cause the welding of an excess of heat-sealing material of at least one of the heat-sealing layers to the opposite heatsealing layer, insulating the edge of the conductive layer of each joining element from the internal volume of the resulting container.

[0012] Document US5031380A discloses a machine for making a tubular container, filling it, cutting the ends, and welding them. Before welding, an aluminum tab cut perpendicularly from a polyethylene-coated tape is positioned at the end of the tube to be welded and welded in place by heating. Further downstream, this end is squeezed by pliers equipped with induction elements, the aluminum tab is heated electromagnetically, and the polyethylene at its sides temporarily melts and welds to the container wall, sealing it.

[0013] In the cited document, as in the prior art more generally, cutting and positioning the aluminum tabs are performed virtually simultaneously. Otherwise, the aluminum tabs would risk being lost after being cut from the tape. The applicant noted that this type of machine does not allow to achieve the desired insulation of the edges of the aluminum tabs exposed to the container's contents, even with wider or more tightly clamped pliers. Furthermore, as already mentioned, even the strength of the weld is often unsatisfactory.

[0014] The known machine, as described in the cited document, does not allow to obtain the insulation of the edge of the conductive layer. Tests conducted by the applicant have shown that, even in the possibility of adding an intermediate station between the welding of the aluminum tab to the tube and the filling of the tube, assigned to heat and press the tab more intensely and / or for a longer period, no significant improvement is achieved. The edges of the aluminum tab remain completely exposed, or only partially covered, and certainly lack the necessary insulation. Such an intermediate station would also require constant stopping and restarting of the tubular substrate sheet, further slowing the entire process.

[0015] Document GB 1161903 A discloses a method and apparatus for welding two edges of a sheet, at least one edge being provided with a thermoplastic surface. A metal strip is inserted between the two edges. When heated by electromagnetic induction, the strip causes the thermoplastic surface to melt, resulting in the two edges welding together. Also in this case, experimental tests have confirmed that by following the teachings of the cited document, it is not possible to obtain a container in which the metal strip is completely, homogeneously, and robustly covered by the thermoplastic material.

[0016] The features of the invention are highlighted below with particular reference to the accompanying drawings, in which:

[0017] Figure 1 illustrates a top view of the improved container object of the present invention;

[0018] Figure 2 illustrates a sectional view along plane II -II of the container of Figure 1; Figure 3 illustrates an enlarged view of a portion of the container of Figure 2;

[0019] Figure 4 illustrates a partial top view of the sheet material of the present invention; Figure 5 illustrates a partial, enlarged, and not-to-scale sectional view along plane V-V of the sheet material of Figure 4;

[0020] Figure 6 illustrates a partial sectional view of the sheet material of Figure 5 in a welding condition;

[0021] Figures 7 to 12 illustrate partial, not-to-scale sectional views of respective variants of the sheet material of Figure 5;

[0022] Figure 13 illustrates a partial top view of a variant of the sheet material of Figure Figure 14 shows a partial, enlarged, and not-to-scale sectional view along plane XIV-XIV of the variant of the sheet material of Figure 13.

[0023] With reference to figures 1 to 14, according to a first aspect, the present invention relates to a sheet material 51 comprising a support means 52 and having one or more regions of any geometric shape, into which the support means 52 is optionally divided. Each region is intended for the manufacturing of a respective container 1, constituting a perimeter wall 3 thereof to be closed at least by electromagnetic induction welding of at least a predetermined welding portion 55 of the support means 52, and more precisely of said region, preferably of at least two transversal welding portions 55 respectively at a bottom portion and at an opposite head portion of the container 1 itself. A welding portion 55 is also preferably intended to provide a longitudinal weld of the perimeter wall 3 of the container 1, which is otherwise closed longitudinally by another type of heat welding or by gluing. Said welds give rise to a corresponding welding condition of the sheet material 51 to provide the container 1.

[0024] The sheet material 51, therefore, may consist of one or more sheets, each provided with one or more regions for manufacturing a corresponding number of containers 1, or, preferably, it is of the strip type wound in a reel, with such regions arranged serially and continuously along the strip.

[0025] The support means 52, in turn, preferably comprises at least one support layer 53 comprising, or based on, paper, cardboard, microfibrillated cellulose (MFC), plastic, polyethylene, other polymeric material, wax, and / or other material or composite or fibers, whether vegetable or synthetic.

[0026] Each of said sealing portions 55 is provided with at least one respective or corresponding joining element 57 for electromagnetic induction welding. Each joining element 57 indeed comprises a thin laminar conductive layer 59 of any shape but preferably rectangular, having a thin perimeter edge 63 corresponding to the thickness of the conductive layer 59 itself and included between a first face 61 and an opposite second face 62 of the latter.

[0027] The conductive layer 59 is preferably made of aluminum, or consists of or is based on another electrically conductive metallic or carbon-based material, conductive polymers, graphene, conductive inks, or the like, such that it heats up when irradiated by electromagnetic radiation of adequate intensity and frequency. The thickness of the conductive layer 59 is preferably uniform and comprised, by way of example but not limited to, in the range from 0.5 pm to 100 pm, more preferably from 3 pm to 50 pm, even more preferably from 5 pm to 10 pm, with preferred thicknesses in the range from 6 pm to 9 pm, wherein here and in the rest of this document the extremes of the ranges are understood to be included unless otherwise specified. A conductive layer 59 of graphene may, for example, have thickness even less than 1 pm, given its very high tensile strength.

[0028] Where the sheet material 51 is a sheet or strip comprising multiple regions, a welding portion 55 with its respective joining element(s) 57 may optionally extend to two adjacent regions of the same sheet or strip, as exemplarily illustrated in Figure 4. Once the two corresponding containers 1 have been formed and welded, these will be separated with a cut along said welding portion 55 (for example, performed along the median line indicated in dashed line in the same Figure 4), and each of them will be left with its own welded welding portion 55, intended as a part (for example, a half) of the original shared welding portion 55.

[0029] To allow the closure and welding of the support means 52, a first adhesive layer 71 of each joining element 57 adheres to the first face 61 of the latter and is fixed to the support means 52, being welded to it (for example, by fusion through the application of heat or by induction), glued or otherwise applied as better specified below.

[0030] The sheet material 51 further comprises at least one second adhesive layer 72, which is preferably already applied and adheres tightly to the second face 62 of the conductive layer 59 of a respective joining element 57, at least in the welding condition of the sheet material 51 itself to obtain the container 1, but more preferably in a sealing condition of the joining elements 57 prior to the welding condition, and whereby at least a section of the perimeter edge 63 of the conductive layer 59 is covered and insulated by the heat-sealing material of one or both of the adhesive layers 71, 72.

[0031] In some variants of the sheet material 51, illustrated in particular in Figures 13 and 14, the second adhesive layer 72 is applied and / or intended to adhere to the second face 62 of the conductive layer 59 of a respective or each joining element 57 only at, or shortly or immediately before, the forming and welding of the sheet material 51 to make the container 1.

[0032] In these variants, the second adhesive layer 72 of each joining element 57 is initially attached to the support means 52, i.e. to the supporting layer 53 or to the coating layer 54 if present. The second adhesive layer 72 is fixed, thermally, mechanically, by gluing, or in another similar manner, in the same welding portion 55 in which are also initially fixed the conductive layer 59 with the first adhesive layer 71 of the corresponding joining element 57. Their mutual position may be adjacent or even spaced apart.

[0033] This second adhesive layer 72 has a respective excess of heat-sealing material, specifically described below, suitable for welding with the first adhesive layer 71 in the following manner: in correspondence with a fold or roll of the support means 52 in a forming phase of the container 1, the second adhesive layer 72 comes to be exactly overlapped on the second face 62 of the corresponding conductive layer 59, with the related excess of heat-sealing material extending beyond the perimeter of the second face 62; in correspondence with a welding phase, the second adhesive layer 72 adheres and welds to the second face 62, in addition to connecting and welding to the first adhesive layer 71 along the perimeter edge 63 or sections thereof, thus completing the welding of the container 1 and at the same time achieving the sealing condition.

[0034] It is also envisaged that the perimeter of the second adhesive layer 72 initially attached to the support means 52 be of identical dimensions to that of the conductive layer 59, with the excess of heat-sealing material assigned to the first adhesive layer 71 or in its thickness.

[0035] Naturally, a similar variant is also provided, wherein the first 71 and second 72 adhesive layers are inverted.

[0036] In general, the first adhesive layer 71 is made of, or consists of, adhesive material, and more specifically, according to the invention, this adhesive material comprises a heatsealing material or several heat-sealing materials mixed together or arranged in layers. Analogously, the second adhesive layer 72 is made of, or consists of, adhesive material that in particular comprises one or several heat-sealing materials, identical or different from those of the first adhesive layer 71. More preferably, the second adhesive layer 72 consists exclusively of heat-sealing material.

[0037] In the present context, a heat-sealing material or heat-sealing adhesive material is intended as a thermoplastic material that, when subjected to a sufficiently high temperature and / or heat, melts, liquefies, or otherwise softens sufficiently to bond, adhering and anchoring to, or mixing and fusing with, materials, surfaces, bodies, or other elements in contact with it, provided that such materials are chemically or physically compatible with fusion and / or adhesion or sticking anchoring with the said heat-sealing material.

[0038] It is in fact sufficient that the heat-sealing material of one adhesive layer 71, 72 can combine by mixing and melting or by simply sticking with the heat-sealing material of the other adhesive layer 72, 71. It is not necessary for the heat-sealing materials of the first adhesive layer 71 and of the second adhesive layer 72 to have the same melting point: for example, the heat-sealing material of the second adhesive layer 72 may have a lower melting point, at which the heat-sealing material of the first adhesive layer 71 is only slightly softened, as long as this allows the two heat-sealing materials in this condition to be able to join and weld to each other.

[0039] Optionally but preferably, the support means 52 further comprises in turn at least one coating layer 54 comprising heat-sealing material, coupled by deposition, lamination or co-extrusion with the support layer 53 on the face thereof which, once the container 1 to be made has been formed, is adjacent to or faces the internal volume 4 of the container 1. At least one of the first adhesive layer 71 and the second adhesive layer 72 of each joining element 57 is then welded or otherwise adherently fixed to the coating layer 54. For example, the support layer 53 has one face completely covered by the coating layer 54, and each joining element 57 or a subset thereof is fixed with the first adhesive layer 71 adhering to the coating layer; each joining element 57 also has its own second adhesive layer 72.

[0040] In some variants, not illustrated, of the sheet material 51, at least one of the first adhesive layer 71 and the second adhesive layer 72 of one or more joining elements 57 consists of the coating layer 54 itself. By way of non-limiting example, this occurs when the joining elements 57, initially without the second adhesive layer 72, are applied by adhering the first adhesive layer 71 directly to the support layer 53, and only subsequently is the coating layer 54 applied to cover both the support layer 53 and the joining elements 57; therefore, the heat-sealing material of the coating layer 54 couples with the exposed areas of the support layer and with the second face 62 of the conductive layer 59 of each joining element 57, constituting at least locally a common second adhesive layer 72.

[0041] In this case, therefore, the coating layer 54 constitutes both a barrier to insulate the support layer 53 from the contents of the container 1, and a single second adhesive layer 72 for all or for each one of the joining elements 57, in the sealing condition or at least in the welding condition of the sheet material 51. In fact, this coating layer 54 is intended to face the second face 62 of the conductive layer 59 of each joining element 57 as a result of the folding of the sheet material 51 and the forming of the container 1, and to weld and adhere to this second face 62 in the welding condition. Indeed, heating the conductive layers 59 locally causes the softening or at least partial melting of the coating layer 54, which thus adheres to each second face 62 and also bonds to each first adhesive layer 71, enveloping and insulating almost entirely the perimeter edge 63 of each conductive layer 59, also creating the sealing condition. Likewise, the first adhesive layer 71 itself may in this case consist of localized portions of the coating layer 54, which at the welding portions 55 serves the function of holding the conductive layer 59 fixed to the support means 52.

[0042] Again, this variant as well is equally applicable by swapping the first adhesive layers 71 and second 72.

[0043] While the support layer 53 primarily provides structural support for the sheet material 51 and the containers 1 that are to be obtained from it, the coating layer 54 primarily serves as a waterproofing or barrier to preserve food or beverages inside the containers 1. Optionally, as just mentioned, the coating layer 54 may also serve as the first adhesive layer 71 and / or second adhesive layer 72 and act as a binder or bridge for the welding between the support layer 53 and the second face 62 of the joining elements 57.

[0044] In a particularly preferred embodiment, the support means 52 comprises the support layer 53 coupled throughout with the coating layer 54. Hence, the joining elements 57 are applied onto the coating layer 54. In the sealing condition, the perimeter edge 63 of the joining elements 57 or sections thereof are covered and sealed by the heatsealing material of the first 71 and / or second 72 adhesive layers. In the welding condition, which leads to obtain the container 1, the coating layer 54 bonds to both the adhesive layers 71, 72.

[0045] The heat-sealing material comprises at least one of polyethylene (PE), low-density polyethylene (LDPE), medium-density polyethylene (MDPE), linear low-density polyethylene (LLDPE), polypropylene (PP), or other plastic polymeric materials.

[0046] Preferably, the heat-sealing material of at least one of the first adhesive layer 71 and the second adhesive layer 72, more preferably of the second adhesive layer 72 and optionally of both adhesive layers 71, 72, further comprises one or more additives mixed or combined therewith, selected from metallocenes, ethylene acrylic acid copolymer (EAA), hyperbranched polymers (HBP), other adhesive polymers, plasticizers, or other compounds or materials similar in composition and / or properties. The addition of one or more of these additives advantageously allows the to improve the seal of the fusion weld that will be subsequently created. Advantageously, the presence of metallocenes or other additives within the heat-sealing adhesive material makes the latter more flexible in the solid form, and more fluid during melting by heating, thus improving its mechanical properties and promoting complete adhesion and a strengthened bond between the joining element 57 and the support means 52 in the welding condition of the sheet material 51, as well as between the first adhesive layer 71 and the second adhesive layer 72 in the sealing condition of the joining element 57.

[0047] In turn, and at least for the same reasons, if the coating layer 54 is provided, its heatsealing material is made of the same material as, or compatible with bonding by adhesion or mutual fusion with, the heat-sealing material and comprises a polymeric material and one or more additives selected from metallocenes, ethylene acrylic acid copolymer (EAA), hyperbranched polymers (HBP), other adhesive polymers, plasticizers, or other similar materials suitable for promoting the adhesion of the coating layer 54 to the second face 62 of the conductive layer 59 and / or the welding between the coating layer 54 and the first adhesive layer 71 and / or second adhesive layer 72.

[0048] When, instead, the support medium 52 does not have a coating layer 54, the heatsealing material of the adhesive layers 71, 72 is still such that it can adhere sufficiently robustly to the support layer 53.

[0049] The thickness of the first 71 and second 72 adhesive layers, in general, is preferably comprised within the range from 1 pm to 1 mm, preferably from 2 pm to 400 pm, more preferably from 3 pm to less than 30 pm, i.e. excluding this latter extreme, for example 29 pm. Within the aforementioned ranges, the two adhesive layers 71, 72 may have the same thickness or even significantly different from each other.

[0050] At least one of the first adhesive layer 71 and the second adhesive layer 72 comprises an excess of heat-sealing material that, at least in the welding condition, is suitable for connecting, and more preferably and precisely at least in the sealing condition is connected - that is, welded - to the opposite second adhesive layer 72 or first adhesive layer 71, respectively, at at least a section of the perimeter edge 63 of the conductive layer 59, completely covering that section and insulating it. Said excess is herein generally understood as an amount of additional heat-sealing material, i.e., an overabundance of such material, compared to the amount essentially necessary or typically sufficient to cover or coat the corresponding first face 61 or second face 62 of the conductive layer 59 foil. The excess of heat-sealing material can take various forms, some of which are presented below by way of non-limiting example.

[0051] Whatever the chosen form, the excess of heat-sealing material is in any case sufficient to connect the first adhesive layers 71 and second adhesive layers 72 to each other over the perimeter edge 63 in such a way that this mutual connection, welding, coupling, or fusion continuously covers said section of the perimeter edge 63, in the sheet material 51 or at least in the final container 1. Preferably, the excess of heat-sealing material, in addition to completely covering the predetermined sections of the perimeter edge 63, adheres and bonds to them so as to leave no empty spaces, i.e., spaces filled with air, in contact with the conductive layer 59, further reducing the perishability of the latter, for example, due to oxidation.

[0052] The excess can therefore preferably take the form of a geometric extension, i.e., one or more edges 75 of the adhesive layer 71, 72 that broaden mainly beyond the perimeter of the conductive layer 59 so as to extend over the perimeter edge 63 towards the opposite face and cover it. This is equivalent to saying that said excess of heatsealing material of the first adhesive layer 71 and / or of the second adhesive layer 72 is such that, in the sealing condition and even more so during the welding condition, it extends beyond the perimeter of the respective first face 61 or second face 62 in correspondence with said at least one section of the perimeter edge 63.

[0053] The length of the protruding edge 75 of the geometric excess with respect to the perimeter of the corresponding face 61, 62 is at least 1 pm, preferably from 1 pm to 2 mm, more preferably from 2 pm to 1 mm, even more preferably from 3 pm to 50 pm, depending in any case also on the thickness of the conductive layer 59 the peripheral edge 63 of which needs to be covered and on the thickness of the heat-sealing material with which it is intended to cover this edge in the sealing condition.

[0054] For example, as illustrated in particular in Figure 7, the second adhesive layer 72 adheres to the second face 62 of the respective conductive layer 59 and has a thickness equal to the first adhesive layer 71, but extends cantilevered with its own excess beyond the perimeter of the conductive layer 59 at two opposite longitudinal sections of the latter. Upon reaching the sealing condition, this excess softens or melts, descending to cover these sections and tightly connecting to the first adhesive layer 71 at the perimeter of the first face 61.

[0055] Similarly, the first adhesive layer 71 may have an excess of heat-sealing material that extends beyond the perimeter of its respective first face 61, as illustrated in Figure 8. In this case, it may be useful to compress the joining element 57 with a perpendicular force, so as to force the softened excess of heat-sealing material to rise along the desired sections of the perimeter edge 63 to connect to the second adhesive layer 72 and achieve the sealing condition.

[0056] Possibly, both the first adhesive layer 71 and the second adhesive layer 72 may extend cantilevered beyond the first face 61 and the second face 62 with their respective excesses, as shown for example in Figure 9.

[0057] In a variant of the joining elements 57, each of these comprises its own respective second adhesive layer 72 adherently fixed to the second face 62 of the conductive layer 59, and both the first adhesive layer 71 and the second adhesive layer 72 extend with their respective excesses beyond the perimeter of the respective first face 61 or second face 62 and are mutually joined and completely welded, i.e., connected as a single body at said at least one section of the perimeter edge 63. Referring for example to Figure 10, the two adhesive layers 71, 72 protrude and are mutually connected along both longitudinal sides of the conductive layer 59, constituting a sort of sheath of heatsealing material that completely envelops the conductive layer 59, completely insulating it along the longitudinal direction. This sheath excess is easily obtained, for example, by co-extrusion. It is clear that in this case the aforementioned sealing condition of the joining elements 57 is met from the beginning.

[0058] With particular reference to Figures 11 and 12, another variant of such joining elements 57 provides that each of these again comprises a respective second adhesive layer 72 adhering to the second face 62, and that said at least one section of the perimeter edge 63 of the conductive layer 59 lies on a respective cutting plane 8 inclined by a respective non-zero angle 9 with respect to the direction perpendicular to the first face 61 and to the second face 62 which, since the conductive layer 59 is laminar, are almost flat and parallel. The perimeter edges of the first adhesive layer 71 and the second adhesive layer 72 also lie on said inclined cutting plane 8 along said section of the perimeter edge 63.

[0059] In other words, the sections of the side edge of a joining element 57 affected by the excesses of heat-sealing material are each cut obliquely along a respective cutting plane 8. Consequently, for each section of the perimeter edge 63, one of the first 71 and second 72 adhesive layers protrudes with an acute-corner edge 75 that protrudes from the perimeter of the respective first 61 or second 62 face, while the opposite second 72 or first 71 adhesive layer has an obtuse edge that recedes from the perimeter of the second 62 or first 61 face. For each of the affected sections, however, there is at least one protruding corner edge 75 of the excess of heat-sealing material. Considering the typical thicknesses and rigidity of the materials involved, the corners along the perimeter edge 63 are flexible and in any case such that they do not compromise the connection between the first 71 and the second 72 adhesive layer, and hence the strength of the sealing and welding and the insulation of the perimeter edge 63 itself. Said angle 9 between each cutting plane 8 and the normal to the first 61 and second 62 faces is preferably in the range from 5° to 85°, preferably from 15° to 75°, more preferably from 30° to 60°, more preferably from 40° to 50°, and even more preferably it is approximately 45°. The indicated values are intended in modulus, meaning that the angle 9 can be either positive (conventionally measured counterclockwise) or negative (measured clockwise).

[0060] If the cut involves more than one section of the perimeter edge 63, for example two opposite longitudinal sections thereof, the angle 9 of each corresponding cutting plane 8 can be the same or different. Figure 11 illustrates, by way of example, two parallel longitudinal cutting planes 8, while in Figure 12 the two cutting planes 8 are symmetrical or mirrored with respect to a median longitudinal plane (not shown) that perpendicularly divides the conductive layer 59.

[0061] In all these cases, the cantilevered edge 75 of the adhesive layer 71, 72 is intended to soften or melt in correspondence with the sealing condition or at least the welding condition, covering the corresponding section of the perimeter edge 63 until it reaches the opposite adhesive layer 72, 71 to which it welds or mixes and connects, and simultaneously adhering to the perimeter edge 63 which is therefore insulated. In some cases, the edge 75 may not even come into connection with the opposite adhesive layer, but may first reach and weld with the support means 52 adjacent to the opposite face 61, 62, actually obtaining the same result of sealing and insulating the perimeter edge 63.

[0062] The described cuts can easily be obtained, for example, from a strip of conductive material, with a width and thickness equal respectively to the transverse dimension and thickness of each conductive layer 59, coated on both sides with heat-sealing material of a thickness equal to that of the first 71 and second 72 adhesive layers, respectively. This strip is cut with a straight blade, oriented obliquely, i.e., inclined at the desired angle 9 with respect to the strip itself, to obtain the individual joining elements 57.

[0063] Despite the extremely thin thickness of the joining elements 57, and therefore of the starting strip, this cutting method surprisingly allows to obtain the joining elements 57 as described with extreme simplicity and speed.

[0064] Alternatively or in addition to the geometric extension beyond the perimeter of the conductive layer 59, the excess of heat-sealing material may take the form of an increased thickness of the first 71 and / or second 72 adhesive layer made of heatsealing material, as a consequence of the addition of heat-sealing material in abundance. In the sealing condition, the conductive layer 59 heats up and causes the heat-sealing material of the first 71 and / or second 72 adhesive layers to soften or melt; optionally, a compression perpendicular to the first 61 and second 62 faces is simultaneously applied to the joining element 57, which causes the softened adhesive layers 71, 72 to be squeezed; the excess of heat-sealing material expands, possibly forced by this pressure, beyond the perimeter of the first face 61 and / or the second face 62, proceeding along one or more sections of the perimeter edge 63 until it joins and connects or welds with the opposite adhesive layer 71, 72, thus isolating said sections and creating the sealing condition.

[0065] An excess of this type is illustrated by way of example in Figure 5, in which both the first 71 and second 72 adhesive layers comprise respective excesses of heat-sealing material in thickness. Figure 6 shows a possible example of the mutual connection between these two first 71 and second 72 adhesive layers comprising heat-sealing material along two opposite sections of the perimeter edge 63 in correspondence with, or following, the welding condition. Crushing performed, for example, using a vise or pliers, causes the thickness of the adhesive layers 71, 72 to decrease, with the excess of heat-sealing material expanding beyond the perimeter edge 63, joining with the material of the opposite layer.

[0066] The fixing of a joining element 57 to the support means 52 at the respective welding portion 55 may be achieved by positioning the joining element 57 with its first adhesive layer 71 in contact with the support means 52 itself (either the support layer 53 or the coating layer 54, if present and already applied), and thus causing the heatsealing material of the first adhesive layer 71 to partially and temporarily melt due to the heat supplied to the conductive layer 59 via conduction by contact with hot elements (e.g., a hot plate, clamp, or pliers), via hot air convection, via infrared radiation, via electromagnetic induction applied to the conductive layer 59 (the heating up of which consequently also heats the heat-sealing material in contact therewith), or in another similar manner. The melted heat-sealing material adheres to the support means 52 and, as it solidifies, anchors the joining element 57 thereto.

[0067] In a variant of the sheet material 51, the first adhesive layer 71 comprises a self- adhesive material at least on the outside, i.e. at least in one layer, section or surface portion of the first adhesive layer 71 on the opposite side with respect to the interface between the latter and the conductive layer 59. Said self-adhesive material is preferably of the pressure-sensitive or contact-sensitive type (PSA), or is chemically activated (e.g. activated by water, solvents, ultraviolet light, etc.), or is of another type equally suitable for use in adhesive labels. This allows the joining elements 57 to be initially provided in the form of labels that can be collected extremely quickly from a release liner, as will be better explained later. In this case, the fixing of a joining element 57 is achieved by simply depositing or applying and pressing the joining element 57 onto the support means 52, so that the self-adhesive material of the first adhesive layer 71 adheres and anchors to the support layer 53 or to the coating layer 54, depending on the embodiment of the support means 52. With great advantage, this solution makes the application of the joining elements 57 much quicker than traditional application methods in which welding with the application of heat is required to make each joining element adhere to the support means.

[0068] Preferably, the self-adhesive material coincides with the heat-sealing material in the first adhesive layer 71, the self-adhesive material being selected to have both pressuresensitive adhesion and heat-sealing properties. Experimental tests have confirmed that such a self-adhesive and heat-sealing material can be selected from those listed below, by way of non-limiting example: block copolymers such as styrene-isoprene-styrene (SIS) or styrene-butadiene-styrene (SBS); ethylene-vinyl acetate (EVA), metallocene- based polyolefins (mPO), or other polyolefin blends; thermoplastic acrylics, which exhibit pressure-sensitive adhesion properties when cooled; combinations of styrene- isoprene-styrene (SIS) with resin and / or asphaltene and naphthenic oil blends; reactive or non-reactive adhesives based on thermoplastic polyurethane (TPU); wherein tackifiers or plasticizers may possibly be added to all of the aforementioned materials. It may also be sufficient for the self-adhesive material to be compatible with mutual fusion welding with the heat-sealing material of the opposite second adhesive layer 72, without the self-adhesive material itself being strictly speaking heat-sealing, as already explained. Alternatively, the first adhesive layer 71 is multi-layered, i.e., it is in turn made up of multiple layered portions of different adhesive materials, with the heat-sealing material distinct from the self-adhesive material and placed in a more internal position, i.e., closer to the conductive layer 59, than the self-adhesive material. For example, the first adhesive layer 71 may comprise a pressure-sensitive self- adhesive material in an outermost portion or layer of the first adhesive layer 71 itself, to which one or more inner layers composed of the same or different heat-sealing materials are adherently associated, intended to soften or melt in order to fuse with the heat-sealing material of the second adhesive layer 72. In any case, as mentioned, the heat-sealing material fraction of the first adhesive layer 71 preferably comprises one or more additives to facilitate the sealing of the peripheral edge 63 of the conductive layer 59.

[0069] In other variants of the sheet material 51, or in addition to the two fastening methods already mentioned, each joining element 57 is fixed to the support means 52 by means of hot glue, cold glue, pressure-sensitive glue PSA, contact glue, chemical glue, ultraviolet (UV)-light-activated glue, or another type of suitable adhesive means, not initially present on the joining elements 57. This adhesive means is applied to the outside of the first adhesive layer 71 and / or to the sealing portion 55 before affixing and fixing a joining element 57 to the support means 52.

[0070] In cases where the joining element 57 is fixed to the support means 52 with a self- adhesive material of the first adhesive layer 71 or with adhesive means applied between the first adhesive layer 71 and the support means 52, the second adhesive layer 72 is provided with a respective excess of heat-sealing material which, in the sealing condition, covers the perimeter edge 63 and welds: to the coating layer 54, if present, around the perimeter of the first face 61, the coating layer 54 locally assuming the role of the first adhesive layer 71; and / or to the first adhesive layer 71. In any case, the perimeter edge 63 is insulated by the heat-sealing material. If the coating layer 54 is not provided but the conductive layer 59 adheres directly to the support layer 53, the latter appears to represent or constitute at least locally the first adhesive layer 71 and is suitable for welding with the second adhesive layer 72, for example because the material of the support layer 53 is or in turn comprises polymeric materials, additives, fibers or other particles of heat-sealing material. The first adhesive layer 71 is thus incorporated into the support means 52 itself and coincides with it.

[0071] An object of the present invention is also an improved container 1 having an internal volume 4 defined by a perimeter wall 3 which is made at least from a sheet material 51 in any one of the embodiments or variants thereof described above, which are clearly understood to be fully incorporated herein and below. The wall 3 may optionally comprise a through opening, initially closed by a removable or breakable seal, possibly provided with a spout or a reinforced edge with an associated cap.

[0072] The perimeter wall 3 has a box-like shape, such as a parallelepiped, cylinder, parallelepiped with rounded corners, pyramid, or other suitable shape for containing food or beverage. The perimeter wall 3 typically has a longitudinal weld, performed by hot air, induction or other heat-sealing method, or by gluing, during the manufacturing process of the container 1 prior to filling the latter by means of a filling machine, and is welded by electromagnetic induction at at least one welding portion 55 of the support means 52 of the sheet material 51, and hence of the container 1.

[0073] Preferably, in the welding condition, the container 1 is induction welded at at least two transverse welding portions 55, one at a bottom portion and the other at an opposite top portion of the container 1. Optionally, the container 1 further comprises one or more longitudinal welding portions 55 suitable for carrying out the aforementioned longitudinal weld.

[0074] The support means 52 of the container 1 manufactured starting from the sheet material 51 preferably comprises a support layer 53 and an internal coating layer 54. The fundamental function of the support layer 53 is to provide structural support to the container 1 once formed, and if coupled or mixed with hydrophobic or impermeable materials, it also makes the support means 52 impermeable to liquids and / or gases to preserve the food or beverage inside the container 1. The coating layer 54, laminated, deposited, co-extruded or otherwise coupled to the support layer 53 on the side of the latter which, once the container 1 is formed, is adjacent to the internal volume 4, can increase the waterproofing effect, acting as a barrier. The coating layer 54 comprises or is made of heat-sealing material suitable for welding as will be better explained below, i.e. capable of softening or melting when subjected to sufficient heat. Furthermore, the heat-sealing material is not affected or deteriorated by the food or beverage that may be inserted into the container 1, at least for the service life or shelflife of the container 1 itself.

[0075] Some variants of the container 1 provide that the support means 52 comprise multiple overlapping coating layers 54, for example because each layer selectively acts as a barrier to liquids or gases, or because one layer acts as a bridge or adhesive to join two adjacent layers. Obviously, even in this case, it is important that the last coating layer 54, i.e., the one in contact with the internal volume 4 and the food or beverage, be made of heat-sealing material.

[0076] Of course, the support layer 53 may also be equipped with one or more coatings on the outer side of the perimeter wall 3.

[0077] Each welding portion 55 of the container 1 is equipped with at least one corresponding joining element 57 designed to allow electromagnetic induction sealing of the welding portion 55 itself. Multiple joining elements 57 may optionally occupy the same welding portion 55, provided that the weld thereby achieved extends to the entire welding portion 55, sealing it completely.

[0078] Each joining element 57 comprises a laminar conductive layer 59 of any shape, but preferably rectangular, having a perimeter edge 63 corresponding to the thickness of the conductive layer 59 itself and comprised between a first face 61 and an opposite second face 62 of the conductive layer 59.

[0079] The conductive layer 59 is made of, or comprises, one or more electrically conductive materials, preferably aluminum, and / or other metallic or carbon-based materials, conductive polymers, graphene, conductive inks, or the like; in this way, when irradiated by an electromagnetic field of adequate frequency and intensity, the conductive layer 59 heats up to achieve induction welding. The conductive layer 59 also advantageously provides mechanical or structural reinforcement for the weld itself.

[0080] Each joining element 57 further comprises a first adhesive layer 71 adhering to the first face 62 and a second adhesive layer 72 adhering or intended to adhere to the second face 62, both comprising heat-sealing material. At least one of the first adhesive layer 71 and the second adhesive layer 72, moreover, comprises, as mentioned, an excess of heat-sealing material that is connected or is suitable for connecting with the opposite second adhesive layer 72 or first adhesive layer 71 to connect them at least in correspondence with a portion of the perimeter edge 63 of the conductive layer 59, sealing and insulating it.

[0081] Preferably, at least one of the first adhesive layer 71 and the second adhesive layer 72, more preferably both, is welded to the coating layer 54 with which the support means 52 is equipped on the side of the internal volume 4. This weld is seamless and therefore complete and gas- and liquid-tight, since the heat-sealing materials of the adhesive layers 71, 72 and the coating layer 54 are welded and joined together by fusion at the welding condition or step.

[0082] In a variant of the container 1, at least one of these adhesive layers 71, 72 is constituted by the coating layer 54 itself, coinciding with the latter. Therefore, once the weld is carried out, the coating layer 54 adheres solidly to the first face 61 and / or the second face 62 of the conductive layer 59 of each joining element 57, constituting the first 71 and / or second 72 adhesive layer thereof.

[0083] For example, each joining element 57 is initially provided with only the first adhesive layer 71, which is used to fix by welding the joining element 57 to the coating layer 54; during the process of forming and welding the container 1, the support means 52 is folded in such a way that the coating layer 54 of the initially free area of the welding portion 55 faces into contact with the second face 62 of said joining element 57; induction heating of the conductive layer 59 causes the coating layer 54 to melt or fuse in that area of the welding portion 55, and then the cladding layer 54 adheres and welds to the conductive layer 59, constituting the second adhesive layer 72 of the joining element 57.

[0084] In another variant of the container 1, when no coating layer 54 is associated with the support layer 53 of the support means 52, the first adhesive layer 71 and the second adhesive layer 72 are welded by fusion and adhere completely to the support layer 53, for example because the latter is made of microfibrillated cellulose (MFC) or in any case contains a percentage of heat-sealing material which, in addition to acting as a waterproof barrier, guarantees such adhesion and therefore the welding.

[0085] For each joining element 57 adjacent to the internal volume 4 of the container 1, i.e. for example at least for each bottom and top weld and possibly for the longitudinal weld, at least one of the first adhesive layer 71 and the second adhesive layer 72 is welded with the opposite second adhesive layer 72 or first adhesive layer 71, respectively, at at least one section of the perimeter edge 63 of the conductive layer 59 of such joining element 57 adjacent to, i.e. bordering or facing, the internal volume 4 of the container 1, covering said section of the perimeter edge 63 and thus separating and keeping isolated the conductive layer 59 of the joining element 57 from the internal volume 4. In other words, the first adhesive layer 71 and the second adhesive layer 72 are mutually connected in correspondence with at least said section of the perimeter edge 63, at which the conductive layer 59 is isolated from the internal volume 4. It is clear from the description of the sheet material 51 that the insulation is achieved by the excess of heat-sealing material of one or both of the adhesive layers 71, 72, during the welding condition or also and preferably previously in the sealing condition.

[0086] This advantageously allows to solve the technical problem of insulating the conductive layer 59 from the food or beverage contained in the container 1, to prevent the conductive material from being released into the food or beverage and contaminating it, and to prevent the food or beverage, particularly if acidic, from damaging the conductive layer 59 itself, potentially causing the failure or weakening of the seal of the weld. At the same time, the application of the conductive material to the support means 52, necessary to perform the induction welding to close the container 1, remains simple and quick thanks to the selected shape of the laminar conductive layer 59, which, together with the first 71 and second 72 conductive layers, forms a joining element 57; furthermore, the weld of the container 1 proves robust due to the shape of the joining element 57.

[0087] Variants of the container 1 provide that the first adhesive layer 71 and the opposite second adhesive layer 72 of each joining element 57 are mutually connected as a single body at least along said section of the perimeter edge 63, meaning that these two adhesive layers 71, 72 coat the perimeter edge 63 even before the weld is actually made. In any case, the weld or connection 73 between the two adhesive layers 71, 72 is at least liquid-tight.

[0088] In other variants of the container 1, the perimeter edge 63 of the conductive layer 59 of each joining element 57 is covered by the weld or connection between the two opposing adhesive layers 71, 72 also in other sections thereof in addition to the one adjacent to the internal volume 4, or it may also be completely covered.

[0089] More specifically, the connection 73, i.e. the weld or junction between the first adhesive layer 71 and the second adhesive layer 72, completely covers said at least one section of the perimeter edge 63 of the conductive layer 59 adjacent to the internal volume 4 of the container 1 with a thickness preferably of at least 1 pm, preferably in the range from 1 pm to 2 mm, more preferably in the range from 2 pm to 1 mm, even more preferably in the range from 3 pm to 50 pm. This latter interval has indeed proven to be a good compromise between the effectiveness and tightness of the insulation of the edge and the saving of heat-sealing material required in the excess. The thickness of this coating of the perimeter edge 63 is preferably uniform or nearly uniform along all or most of the covered section, but it could also be non-uniform without compromising the insulation effect provided by the conductive layer 59, provided that the coating is complete or continuous, i.e., without interruptions in said section.

[0090] According to another aspect, the present invention also concerns a method for manufacturing a sheet material 51 intended in turn for the manufacturing of a container 1, the sheet material 51 and the container 1 being of the type described above in any variant or form thereof, or of a different but equivalent type and having the components and features necessary to carry out the method as indicated below.

[0091] Said method essentially comprises the phases of: providing, i.e., equipping oneself with or starting from, a support means 52 having at least one welding portion 55; fixing one or more joining elements 57 to the support means 52 at respective welding portions 55, each joining element 57 comprising a conductive layer 59 having a perimeter edge 63 comprised between a first face 61 and an opposite second face 62, making a first adhesive layer 71 of the joining element 57, adhering to the first face 61 thereof, adhere to the support means 52, the first adhesive layer 71 comprising or being made of heat-sealing material as previously mentioned; connecting, i.e. causing the connection of, an excess of heat-sealing material of the first adhesive layer 71 and / or of a second adhesive layer 72, the latter adhering to the second face 62 of a respective or of each joining element 57 and in turn comprising heat-sealing material, with the opposite second adhesive layer 72 or first adhesive layer 71, respectively, in correspondence with at least one section of the perimeter edge 63, insulating the latter, achieving the sealing condition of the joining elements 57 and thus obtaining the sheet material 51.

[0092] Depending on the composition of the first adhesive layer 71, the fixing of the joining elements 57 can be achieved in various ways, alternative to each other or sometimes combinable together.

[0093] If the first adhesive layer 71 comprises, at least on the outside, i.e., on the side opposite to the conductive layer 59, a self-adhesive material of the pressure-sensitive, chemically activated, or of other type suitable for labels, whether it coincides with the heat-sealing material or is separate therefrom in a dedicated layer, the fixing phase involves at least depositing or applying with pressure each joining element 57 on the support means 52 at the respective sealing portion 55. The self-adhesive material sticks to the support means 52, possibly to the coating layer 54 thereof, and creates an at least temporary but preferably stable and robust anchorage.

[0094] In a particularly preferred variant of the method, which has experimentally proven to be unexpectedly and particularly advantageous, the fixing phase provides that the conductive layer 59 of the joining elements 57, and consequently the first adhesive layer 71, is not heated, thanks to the particular choice of the self-adhesive material of the first adhesive layer 71 which allows a definitive fixing to be directly achieved exclusively by the grip it provides on the support means 52. This material, which is both self-adhesive and heat-sealing, can be chosen, by way of non-limiting example, from those listed below: block copolymers such as styrene-isoprene-styrene (SIS) or styrene-butadiene-styrene (SBS); ethylene-vinyl acetate (EVA), metallocene-based polyolefins (mPO) or other polyolefin blends; thermoplastic acrylics, which once cooled exhibit pressure adhesion properties; combinations of styrene-isoprene-styrene (SIS) with mixtures of resin and / or asphaltene and naphthenic oil; reactive or non- reactive adhesives based on thermoplastic polyurethane (TPU); wherein tackifiers or plasticizers may possibly be added to all of the aforementioned materials. It is therefore not necessary, during the fixing phase, to apply heat in order to soften or melt the adhesive and / or heat-sealing material to consolidate and make the bond between the first adhesive layer 71 and the support means 52 sufficiently strong and, if necessary, watertight. This allows the joining elements 57 to be applied to the support means 52 in extremely rapid succession, the joining elements 57 being of the label type or format explained in detail below.

[0095] According to another alternative embodiment, the fixing phase involves attaching each joining element 57 to the support means 52 using hot glue, cold glue, pressuresensitive glue, contact glue, chemical glue, UV-light-activated glue, or other suitable type of adhesive means. Said adhesive means is applied to the welding portions 55 and / or to the outer surface of the first adhesive layer 71 before making them adhere to each other.

[0096] Optionally, in some variants of the method this includes, between the fixing and connecting phases, the phase of applying the second adhesive layer 72 to the second face 62 of the conductive layer 59 of each joining element 57.

[0097] This phase is necessary, for example, in cases where the joining elements 57 are provided in an initial semi-finished form comprising only the conductive layer 59 and the first adhesive layer 71, where the second adhesive layer 72 is therefore intended to adhere to the respective second face 62. For example, if the joining elements 57 are applied to the support means 52 in the form of a label with only one adhesive layer (the first 71), it is necessary to apply the second adhesive layer 72 to the second face 62 before the connecting phase can be performed.

[0098] One of these cases occurs in particular when the second adhesive layer 72 of one or more joining elements 57 is expected to consist of the coating layer 54 of the support means 52, which at least locally also has the function of second adhesive layer 72 for the joining elements 57 covered by it. Therefore, in this case the said applying phase involves coupling to the support layer 53 of the support means 52 a coating layer 54 of the support means 52 itself and comprising heat-sealing material, which constitutes the second adhesive layer 72 of each covered joining element 57. Said coating layer 54 adheres to the conductive layer 59 of each covered joining element 57 with an excess of heat-sealing material which, extending continuously above the joining elements 57, completely covers the perimeter edge 63 and welds to the opposite first adhesive layer 71. In this way, the phase of connecting the two adhesive layers 71, 72 across the perimeter edge 63 is also performed simultaneously, either by direct connection, or equivalently because the welding between the coating layer 54 and the support layer 53 in any case causes the insulation of the perimeter edge 63.

[0099] Another of these cases is illustrated in Figures 13 and 14, wherein each second adhesive layer 72 is applied to the sheet material 51 adjacent to, or in any case separated from, the respective joining element 57. Similarly, this also occurs when the joining elements 57 are attached with the first adhesive layer 71 on the coating layer 54 already deposited on the support means 52, the coating layer 54 being again intended to form the second adhesive layers 72. Then, the said applying phase provides that the support means 52 is folded so as to overlap and match each second adhesive layer 72 with the second face 62 of the respective joining element 57. This is preferably performed at the same time as the forming of the container 1 manufactured from the sheet material 51, as will be better explained later on. The adhesion of the second adhesive layer 72 to the respective second face 62 and the connection with the respective first adhesive layer 71 then take place at the same time as the final welding of the container 1 thanks to the heat used in such phase or operation.

[0100] In general, but not necessarily, also depending on the type of joining elements 57 used, the connecting phase involves in particular heating at least said excess of heat-sealing material by conduction through contact with hot elements (for example a hot plate, vise or pliers), by convection of hot air, by infrared radiation, by electromagnetic induction applied to the conductive layer 59 (the heating up of which consequently also heats the heat-sealing material in contact therewith), or in another similar way. This heating temporarily softens or even completely melts the excess of heat-sealing material, which can then easily distribute along the perimeter edge 63.

[0101] To facilitate this distribution, the connecting phase optionally also involves compressing the heated excess of heat-sealing material with a crushing force directed perpendicularly to the first 61 and second 62 faces of the joining element 57. This pressure squeezes the adhesive layers 71, 72 and causes their respective excesses to move laterally toward and beyond the perimeter edge 63, covering it until they join together and thus sealing it.

[0102] If the said self-adhesive material, if present, of the first adhesive layer 71 provides only a temporary or too weak fixing, only suitable for holding the joining element 57 in its predefined position in the welding portion 55, it is optionally provided that the first adhesive layer 71 is heated so that its heat-sealing material, even if coinciding with the self-adhesive material, is permanently welded to the support means 52. The heat required for fixing can be supplied specifically during the fixing phase itself, or it can be that applied during the connecting phase, which in addition to causing insulation or sealing also causes the definitive anchoring of the first adhesive layer 71 to the support means 52.

[0103] In the variants in which it is envisaged that the starting sheet material 51 be provided with joining elements 57 of the type with the excesses of heat-sealing material lying on an inclined cutting plane 8, the providing phase of the method can further include the step of obtaining the joining elements 57 by cutting each one of them from a strip of conductive material, wherein the cut is made with a blade inclined with respect to the strip at a desired, selectable angle 9 preferably in the range from 5° to 85°, preferably from 15° to 75°, more preferably from 30° to 60°, more preferably from 40° to 50°, and even more preferably approximately 45°.

[0104] In a further aspect of the present invention, it relates to a method for manufacturing one or more improved containers 1 starting from a sheet material 51, as those described above or with different but equivalent characteristics to those said of the container 1 and the sheet material 51.

[0105] The method comprises the following phases: providing a sheet material 51 comprising a support means 52 and having one or more regions of any geometric shape, each one intended for the manufacturing of a respective container 1 ; forming at least one region of the sheet material 51 to constitute a perimeter wall 3 defining an internal volume 4 of a respective semi-finished container, said perimeter wall 3 being equipped with at least one predetermined welding portion 55 provided with at least one corresponding joining element 57 suitable for electromagnetic induction welding; welding, by means of electromagnetic induction applied to the joining elements 57, the perimeter wall 3 of the semi-finished container at said at least one welding portion 55, obtaining a respective container 1.

[0106] As already discussed in detail, each joining element 57 comprises a median conductive layer 59, having a perimeter edge 63 comprised between a first face 61 and an opposite second face 62 thereof, and further comprises a first adhesive layer 71 adhering to the first face 61 and a second adhesive layer 72 adhering to, or, depending on the case, intended to adhere to, the second face 62. The first adhesive layer 71 and the second adhesive layer 72 comprise or are made of heat-sealing material.

[0107] Although not explicitly mentioned, the method may also typically comprise a phase of introducing a food, beverage, or other type of product into the internal volume 4 of the semi-finished container before welding and closing it.

[0108] Preferably, the sheet material 51 is in strip or reel form and bears a plurality of adjacent regions arranged in series. For each region there are preferably at least two welding portions 55 transverse to the strip, intended to create a bottom weld and a top weld of the container 1, respectively.

[0109] The support means 52 consists of a support layer 53 to which a coating layer 54 is preferably coupled as an impermeable barrier.

[0110] The first 71 and the second 72 adhesive layer are made of heat-sealing material, compatible for welding with the support means 52 and possibly identical or compatible for welding with the material of the coating layer 54, if present.

[0111] The forming phase involves folding, tubing, or otherwise shaping one region, or more regions at the same time, of the sheet material 51 to form corresponding semi-finished containers. This phase may also include thermal or induction welding, or longitudinal gluing of two opposite edges of the sheet material 51 which, once wrapped or folded, become adjacent or overlapping.

[0112] The welding phase, in particular, comprises the following steps: heating the conductive layer 59 of each joining element 57 by irradiating it with an electromagnetic field of appropriate frequency and intensity, i.e. by electromagnetic induction, the diffusion of heat causing the complete or partial melting (i.e. a localized softening or melting) of the first adhesive layer 71 and the second adhesive layer 72 at least in correspondence with the conductive layer 59 itself, and consequently causing the welding of the first adhesive layer 71 to the support means 52 and / or the welding of the second adhesive layer 72 to the support means 52 and / or the welding of the second adhesive layer 72 to the second face 62 of the joining elements 57, depending on the form of the joining elements 57 and on how they are fixed to the starting sheet material 51 , as already described; compressing the at least one welding portion 55, from the outside of the perimeter wall 3 of the semi-finished container which is also compressed, with a pressure directed perpendicularly on both lateral faces 61, 62 of the respective joining element 57, causing the crushing of the joining elements 57 and the connection or welding of an excess of heat-sealing material of the first 71 and / or second 72 adhesive layer to the opposite second 72 or first 71 adhesive layer in correspondence with at least one section of the perimeter edge 63 of the conductive layer 59 adjacent to the internal volume 4 of the container 1 so welded and obtained, sealing said section of the perimeter edge 63 and insulating and keeping the corresponding conductive layer 59 separate from the internal volume 4 and its contents.

[0113] This insulation of the conductive layer 59 from the internal volume 4, and in particular from the product contained in the container 1, makes the container 1 itself improved compared to known containers.

[0114] The compressing step is preferably performed by at least one pliers or vise means with a width equal to or greater than the width, or transverse dimension, of the conductive layer 59, and is performed simultaneously with or immediately following the heating step.

[0115] The jaws of this pliers or vise means are preferably equipped with coils for electromagnetic induction. During operation and execution of the method, the pliers means grasps the semi-finished container at one or more of its welding portions 55 and its coils irradiate the corresponding conductive layers 59, performing the heating step; the pressure of the jaws may optionally be increased according to a predetermined time profile during or following heating, to cause in each welding portion 55 the connection and welding of the first 71 and second 72 adhesive layers, thus realizing the compressing step.

[0116] More specifically, the intensity of the pressure applied by the pliers means to each welding portion 55 during the compressing step is preferably variable and electronically controlled according to a predetermined algorithm and as a function of at least one of the following operational and design parameters: amount of the excess of heat-sealing material, for example this excess being provided in the form of thickening of one or both of the adhesive layers 71, 72; geometry of the excess of heat-sealing material, for example depending on the size of the edges 75 of the adhesive layers 71, 72 protruding from the perimeter of the respective face 61, 62; desired thickness of the weld or connection between the first 71 and second 72 adhesive layers covering the affected sections of the perimeter edge 63; temperature reached by the heat-sealing material as a result of the heating step; viscosity of the heat-sealing material fully or partially melted at the temperature reached during heating; profile or temporal progression of the heating, i.e., of the power of the electromagnetic field radiated for electromagnetic induction; overall duration of the compressing step, i.e., of the application of pressure.

[0117] The intensity or value of the applied pressure is preferably in the range from 50 kg / cm2to 1,000 kg / cm2, preferably from 100 kg / cm2to 750 kg / cm2, more preferably from 200 kg / cm2to 500 kg / cm2, and even more preferably from 300 kg / cm2to 360 kg / cm2.

[0118] Depending on the initial conformation of the sheet material 51, and in particular of its joining elements 57, the heating step achieves the purpose of welding the first 71 and / or second 72 adhesive layers to the support means 52 according to possible slightly different operating sequences or procedures. Regardless of the procedure followed, the final result is the desired welding of the welding portions 55 of the perimeter wall 3 of each container 1.

[0119] First, partial or complete melting of the adhesive layers 71, 72 occurs at least locally and in correspondence with the area thereof in contact with a corresponding irradiated conductive layer 59, or even just in a central zone of said area, or possibly just beyond the perimeter of the conductive layer 59 thanks to the diffusion of heat by conduction through the material of the adhesive layers 71, 72 themselves. This occurs in particular in the case described in which the coating layer 54 constitutes a first 71 and / or second 72 adhesive layer common to all the joining elements 57: only the areas of the coating layer 54 that, after forming the semi-finished container, face into contact with the first 61 or second 62 face of a conductive layer 59, respectively, will be locally affected by melting or softening.

[0120] If initially both the first 71 and the second 72 adhesive layers already adhere to their respective conductive layers 59, and each joining element 57 is already attached to the support means 52, as exemplified in Figures 5 to 12, then the heating step also involves welding the second adhesive layer 72 to the support means 52 facing it following the forming process. The simultaneous melting of the heat-sealing material in the first adhesive layer 71 possibly contributes to strengthening its bond with the support means 52.

[0121] If initially the joining element 57 is only removably attached to the support means 52, for example by temporarily gluing the first adhesive layer 71, the heating step also causes a robust and definitive proper welding of the first adhesive layer 71 to the support means 52.

[0122] If, however, the second adhesive layer 72 is not initially adherently coupled to the corresponding second face 62, two cases are possible: the second adhesive layer 72 is already applied and welded to the support means 52, as shown for example in Figures 13 and 14: then the heating step causes the second adhesive layer 72 to adhere and weld to the second face 62 of the corresponding conductive layer 59, which it faces and is in contact with following the forming phase; the second adhesive layer 72 is applied to the second face 62 during the forming of the semi-finished container or immediately before: then the heating step causes the second adhesive layer 72 to weld to both the support means 52 and said second face 62.

[0123] In both of the aforementioned cases, the connecting phase (and possibly the immediately preceding applying phase) of the method for manufacturing the sheet material 51 is carried out and coincides with the welding phase (in the heating step or at the latest in the compressing step) of the method for manufacturing the container 1. This is equivalent to saying that the heating or compressing step provides for the desired pairing of the second adhesive layers 72 with the second faces 62 of the respective joining elements 57 and for the desired insulation or sealing of the predetermined sections of the perimeter edge 63 of each conductive element 59 thanks to the connection between the first 71 and the second 72 adhesive layer, or between one of these and the coating layer 54 if this acts as the first 71 and / or second 72 adhesive layer.

[0124] At least in the last cases presented, or when the sheet material 51 comes without the joining elements 57, or when the joining elements 57 are already applied to the support means 52 but only in a removable manner, or when the second adhesive layer 72 is not yet applied adherently to the second face 62, the providing phase is carried out according to at least the following steps: providing a support means 52 having at least one welding portion 55; fixing a first adhesive layer 71 of at least one respective joining element 57, adhering to the first face 61 of the respective conductive layer 59 and comprising heat-sealing material, to the support means 52 in correspondence with each welding portion 55; applying a second adhesive layer 72 made of heat-sealing material to the second face 62 of each conductive layer 59.

[0125] In the applying step, it is understood that the second adhesive layer 72 is applied in such a way as to connect to the opposite first adhesive layer 71, insulating it, preferably in the sealing condition, i.e., before starting the manufacturing of the container 1, or in any case within the welding condition that determines the completion of the manufacturing of the container 1.

[0126] Optionally, the method also includes a phase of cutting or scoring at least a welding portion 55 comprised or shared between two adjacent or consecutive containers 1, obtained from two adjacent or consecutive regions of the same sheet material 51. The cutting or scoring is preferably performed simultaneously with or immediately following the compressing step, using blades or tips, for example, associated with the jaws of the pliers or operable to close and between them. In this way, each individual container 1 manufactured is separated from the other containers 1 possibly produced or being produced from the same sheet material 51, typically in reel form.

[0127] Alternatively, or more generally, however, the phase of providing the sheet material 51 is performed according to any of the embodiments described above for manufacturing a sheet material 51.

[0128] According to another aspect, the present invention also concerns a joining element 57 suitable for induction welding a sheet material, and in particular and preferably suitable or usable in the manufacturing and welding of a sheet material 51 according to one of its embodiments or variants described above, as compatible, to obtain a container 1 in which the conductive parts of the welds are insulated from the contents. Said joining element 57 comprises a laminar conductive layer 59 for induction welding, preferably made of aluminum, graphene, or another material that is a good conductor of electricity. The conductive layer 59 has a first face 61 and an opposite second face 62, between which is comprised a perimeter edge 63 corresponding to the thickness of the conductive layer 59 itself. The joining element 57 also has a first adhesive layer 71 adhering to the first face 61 and a second adhesive layer 72 adhering to the second face 62. Said first 71 and second 72 adhesive layers comprise or are made of heat-sealing material.

[0129] In particular, at least one of the first adhesive layer 71 and the second adhesive layer 72 comprises an excess of heat-sealing material that is connected, or that in a sealing condition of the joining element 57 is suitable for connecting, with the opposite second adhesive layer 72 or first adhesive layer 71, respectively, in correspondence with at least one section of the perimeter edge 63 of the conductive layer 59, insulating or sealing said at least one section.

[0130] In some embodiments of the joining element 57, the first adhesive layer 71 comprises at least on the outside a pressure-sensitive, chemically activated, or other type of self- adhesive material suitable for labels, which coincides with, or is in a separate layer distinct from, the heat-sealing material of the same first adhesive layer 71.

[0131] In this case, preferably, the joining element 57 is in the form of a label, provided on a silicone or waxed release liner or other support from which it is removable or detachable to be subsequently deposited, pressed or otherwise attached to a support means 52 of the sheet material 51 to be manufactured. This means that one or more joining elements 57 are provided on a release liner to which they are removably glued with an adhesive layer 71, 72, more precisely with the self-adhesive material of the first adhesive layer 71.

[0132] In some variants, said excess of heat-sealing material of the first adhesive layer 71 and / or the second adhesive layer 72 extends beyond the perimeter of the respective first face 61 or second face 62 in correspondence with said at least one section of the perimeter edge 63.

[0133] Particularly in one of these variants, shown by way of example in Figure 10, both the first adhesive layer 71 and the second adhesive layer 72 extend with respective excesses of heat-sealing material beyond the perimeter of the respective first face 61 or second face 62, respectively, protruding along the perimeter edge 63, and are mutually welded at said at least one section of the perimeter edge 63.

[0134] In other of these variants, the sections of the lateral edge of a joining element 57 affected by excesses of heat-sealing material are each cut obliquely along a respective cutting plane 8, as already explained and illustrated by way of example in Figures 11 and 12.

[0135] In other variants, the excess of material takes the form of a thickening of the respective adhesive layer 71, 72.

[0136] Preferably, the heat-sealing material of one or both of the adhesive layers 71, 72 comprises one or more additives selected from metallocenes, ethylene acrylic acid copolymer (EAA), hyperbranched polymers (HBP), other adhesive polymers, plasticizers, or other compounds or materials similar in composition and / or properties. According to a further aspect, the present invention also concerns a machine suitable for producing a sheet material 51 as described above with the associated joining elements, and possibly also suitable for forming, filling, and sealing a container 1 as described above.

[0137] Such a machine comprises at least: means for fixing the joining elements 57 to the support means 52 at the respective welding portions 55, suitable for making the first adhesive layer 71 adhere to the support means 52; means for connecting (or causing the connection) the excess of heat-sealing material of the first 71 and / or second 72 adhesive layers with the opposite adhesive layer 72, 71 in correspondence with the at least one portion of the perimeter edge 63 to be sealed, insulating it.

[0138] The operation modes of the means for fixing and the means for connecting are clear to those skilled in the art, in light of the methods for manufacturing a sheet material 51 and a container 1 already described above.

[0139] In particular, when the joining elements 57 are in the format of labels provided on a release liner, the machine of the invention is or comprises means typical of a labeling machine, further comprising means for picking the joining elements 57 from their release liner and means for depositing or pressure applying each joining element 57 at a respective welding portion 55 of the support means 52. These means and machines are normally used in the labeling sector and are known in that field.

[0140] A labeling machine can operate continuously and apply the joining elements 57 by simply by depositing them in succession on the support means 52, generally without the need to intermittently stop the advancement of the support means 52 to apply the joining elements 57, as conversely is currently the case with all the known machines designed to apply the joining elements to a sheet material intended to be closed by induction welding to form the corresponding containers. This provides enormous advantages in terms of efficiency in the production process, with increased production speeds and simplification of the necessary machinery, as labeling machines are already widely used in the food cartons production sector, even though they have never been used in the manner and for the purpose here described to apply joining elements 57 for induction welding. Alternatively, in the case where the joining elements 57 are of the type to be cut obliquely along cutting planes 8 starting from a strip or reel, the machine of the invention may optionally comprise means for feeding the strip and for cutting obliquely the individual joining elements 57. For example, the means for fixing may themselves be designed and adapted to this operation as well.

[0141] The means for connecting the excess of heat-sealing material comprise contact or electromagnetic induction heating means (such as presses, vise, pliers, or other means equipped with electrical resistors or electromagnetic induction coils), hot air heating means, or the like. These means are designed to concentrate on the joining elements 57 a quantity of heat sufficient to cause the temporary, partial, or complete melting of the excesses of heat-sealing material to induce the mutual connection of the adhesive layers 71, 72 and the insulation of at least the predetermined sections of the perimeter edge 63 to be sealed in the sealing condition. This heat can also promote, stabilize, cause, or reinforce the welding of the welding portions 55 of the containers 1 filled with food, beverages, or other products using the machine's filling means, to close the containers 1 thus manufactured and filled, if the machine is also designed for this purpose and does not limit at manufacturing a sheet material 51.

[0142] Preferably, said means for connecting the excess of heat-sealing material further comprise, or coincide with, pliers or press means used to compress the excess of heatsealing material, acting perpendicularly to the faces 61, 62 of the joining element 57. In addition to the advantages explicitly indicated, those skilled in the art will appreciate further advantages provided by the invention in its various aspects, even if not explicitly mentioned here.

Claims

CLAIMS1) Sheet material comprising a support means (52) and having one or more regions each intended for the manufacturing of a container (1) at least by electromagnetic induction welding of at least one predetermined welding portion (55) thereof; said at least one welding portion (55) being provided with at least one joining element (57) for induction welding; each joining element (57) comprising a conductive layer (59) having a perimeter edge (63) comprised between a first face (61) and an opposite second face (62), and comprising a first adhesive layer (71) adhering to the first face (61) and fixed to the support means (52); the sheet material (51) comprising at least one second adhesive layer (72) adhering or intended to adhere to the second face(62) of the conductive layer (59) of a respective or each joining element (57); the first adhesive layer (71) and the second adhesive layer (72) comprising heat-sealing material; the sheet material (51) being characterized in that at least one of the first adhesive layer (71) and the second adhesive layer (72) comprises an excess of heat-sealing material which is connected or is suitable for connecting with the opposite second adhesive layer (72) or first adhesive layer (71) in correspondence with at least one section of the perimeter edge(63) of the conductive layer (59) insulating it.2) Sheet material according to claim 1 characterized in that the heat-sealing material of at least one of the first adhesive layer (71) and the second adhesive layer (72) comprises one or more additives selected from metallocenes, ethylene acrylic acid copolymer (EAA), hyperbranched polymers (HBP), plasticizers, or other similar materials.3) Sheet material according to claim 1 or 2 characterized in that the supportmeans (52) comprises a support layer (53) comprising, or based on, paper, cardboard, microfibrillated cellulose, plastic, polyethylene, polymeric material, wax, and / or other material or fibers, vegetable or synthetic.4) Sheet material according to claim 3 characterized in that the support means (52) further comprises at least one coating layer (54) coupled to the support layer (53) and comprising heat-sealing material, wherein at least one of the first adhesive layer (71) and the second adhesive layer (72) is fixed to, or consists of, the coating layer (54) itself.5) Sheet material according to any one of the preceding claims characterized in that the first adhesive layer (71) comprises, at least on the outside, self- adhesive material of the pressure-sensitive type, or chemically activated, or of other type suitable for labels.6) Sheet material according to claim 5 characterized in that in the first adhesive layer (71) the heat-sealing material coincides with said self-adhesive material or is distinct from it and more internal than the self-adhesive material.7) Sheet material according to any one of the preceding claims characterized in that each joining element (57) is fixed to the support means (52) by means of hot glue, cold glue, pressure-sensitive glue, contact glue, chemical glue, UV- light-activated glue, or other type of adhesive means.8) Sheet material according to any one of the preceding claims characterized in that said excess of heat-sealing material of the first adhesive layer (71) and / or of the second adhesive layer (72) extends beyond the perimeter of the respective first face (61) or second face (62) in correspondence with said at least one section of the perimeter edge (63).9) Sheet material according to any one of the preceding claims characterized inthat each joining element (57) comprises a respective second adhesive layer (72) adhering to the second face (62), and both the first adhesive layer (71) and the second adhesive layer (72) extend with respective excesses of heatsealing material beyond the perimeter of the respective first face (61) or second face (62) and are mutually welded in correspondence with said at least one section of the perimeter edge (63).10) Sheet material according to any one of the preceding claims characterized in that the thickness of the adhesive layers (71, 72) is in the range from 1 pm to 1 mm, preferably from 2 pm to 400 pm, more preferably from 3 pm to less than 30 pm.11) Container having a perimeter wall (3), made at least from one sheet material (51) according to any one of the preceding claims, the perimeter wall (3) defining an internal volume (4) of the container and being welded at least by electromagnetic induction at at least one welding portion (55) of the support means (52) provided with at least one joining element (57) for induction welding; the container (1) being characterized in that, for each joining element (57) adjacent to the internal volume (4) of the container (1), the first adhesive layer (71) and the second adhesive layer (72) are mutually connected in correspondence of at least one section of the perimeter edge (63) of the conductive layer (59) adjacent to the internal volume (4) of the container (1), insulating the conductive layer (59) from the internal volume (4).12) Container according to claim 11 characterized in that the connection between the first adhesive layer (71) and the second adhesive layer (72) completely covers said at least one section of the perimeter edge (63) of the conductive layer (59) with a thickness of at least 1 pm, preferably in the range from 1 pmto 2 mm, more preferably in the range from 2 pm to 1 mm, more preferably included in the range from 3 pm to 50 pm.13) Container according to claim 11 or 12 characterized in that the support means (52) further comprises at least one coating layer (54) coupled to a support layer (53) and comprising heat-sealing material, where at least one of the first adhesive layer (71) and the second adhesive layer (72) is constituted by the coating layer (54) itself.14) Method for manufacturing a sheet material (51), the method being characterized by comprising the phases of: providing a support means (52) having at least one welding portion (55); fixing at least one joining element (57) to the support means (52) at a respective welding portion (55), each joining element (57) comprising a conductive layer (59) having a perimeter edge (63) comprised between a first face (61) and an opposite second face (62), making a first adhesive layer (71) of the joining element (57), adhering to the first face (61), adhere to the support means (52), the first adhesive layer (71) comprising heat-sealing material; connecting an excess of heat-sealing material of the first adhesive layer (71) and / or of a second adhesive layer (72) comprising heat-sealing material adhering to the second face (62) of a respective or of each joining element (57) with the opposite second adhesive layer (72) or first adhesive layer (71) in correspondence with at least one section of the perimeter edge (63) insulating it, obtaining the sheet material (51).15) Method according to claim 14 characterized in that the fixing phase involves depositing or applying with pressure each joining element (57) at therespective welding portion (55), the first adhesive layer (71) comprising, at least on the outside, self-adhesive material of the pressure-sensitive type, or chemically activated, or of another type suitable for labels, coinciding with, or distinct from, the heat-sealing material.16) Method according to claim 15 characterized in that the fixing phase provides that the conductive layer (59) of the joining elements (57) is not heated, the fixing being carried out exclusively by the self-adhesive material of the first adhesive layer (71).17) Method according to claim 14 characterized in that the fixing phase involves attaching each joining element (57) to the support means (52) using hot glue, cold glue, pressure-sensitive glue, contact glue, chemical glue, UV-light- activated glue, or other type of adhesive means.18) Method according to any one of claims 14 to 17 characterized in that it further comprises, between the phases of fixing and connecting, the phase of applying the second adhesive layer (72) to the second face (62) of the conductive layer (59) of each joining element (57).19) Method according to claim 18 characterized in that said applying phase involves coupling to a support layer (53) of the support means (52) a coating layer (54) of the support means (52) comprising heat-sealing material and constituting the second adhesive layer (72) of each joining element (57), said coating layer (54) adhering to the conductive layer (59) of each joining element (57) with an excess of heat-sealing material which completely covers the perimeter edge (63) and welds to the opposite first adhesive layer (71) thus also performing the connecting phase.20) Method according to any one of claims 14 to 19 characterized in that theconnecting phase involves heating at least said excess heat-sealing material by conduction through contact, hot air, electromagnetic induction applied to the conductive layer (59), or in another way.21) Method according to claim 20 characterized in that the connecting phase also involves compressing the heated excess of heat-sealing material perpendicularly to the joining element (57).22) Method for manufacturing one or more containers (1), comprising the following phases: providing a sheet material (51) comprising a support means (52) and having one or more regions; forming at least one region of the sheet material (51) to constitute a perimeter wall (3) defining an internal volume (4) of a respective semifinished container, and which is equipped with at least one welding portion (55) provided with at least one joining element (57) for induction welding; welding, by electromagnetic induction, the perimeter wall (3) at the at least one welding portion (55) obtaining a respective container (1); each joining element (57) comprising a conductive layer (59), having a perimeter edge (63) comprised between a first face (61) and an opposite second face (62), a first adhesive layer (71) adhering to the first face (61), and a second adhesive layer (72) adhering or intended to adhere to the second face (62); the first adhesive layer (71) and the second adhesive layer (72) comprising heat-sealing material; the method being characterized in that the welding phase comprises the following steps: heating the conductive layer (59) of each joining element (57) with anelectromagnetic field, causing the partial or complete melting of the first(71) and second (72) adhesive layers at least at the conductive layer (59), and causing the welding of the first adhesive layer (71) to the support means (52) and / or the welding of the second adhesive layer (72) to the support means (52) and / or to the second face (62); compressing the at least one welding portion (55), from the outside of the perimeter wall (3), with a pressure directed on the at least one joining element (57), causing the connection of an excess of heat-sealing material of the first (71) and / or second (72) adhesive layer to the opposite second(72) or first (71) adhesive layer in correspondence with at least one section of the perimeter edge (63) of the conductive layer (59) adjacent to the internal volume (4) of the container (1), insulating the conductive layer (59) from the internal volume (4).23) Method according to claim 22 characterized in that the providing phase comprises the following steps: providing a support means (52) having at least one welding portion (55); fixing a first adhesive layer (71) of at least one joining element (57), adhering to the first face (61) of the respective conductive layer (59) and comprising heat-sealing material, to the support means (52) in correspondence with each welding portion (55); applying a second adhesive layer (72) made of heat-sealing material to the second face (62) of each conductive layer (59).24) Method according to claim 22 or 23 characterized in that the step of providing is carried out according to the method for manufacturing a sheet material (51) according to any one of claims 14 to 21.25) Joining element for induction welding of a sheet material (51), the joining element (57) comprising a conductive layer (59) for induction welding having a perimeter edge (63) comprised between a first face (61) and an opposite second face (62), a first adhesive layer (71) adhering to the first face (61), and a second adhesive layer (72) adhering to the second face (62); the first adhesive layer (71) and the second adhesive layer (72) comprising heatsealing material; the joining element (57) being characterized in that at least one of the first adhesive layer (71) and the second adhesive layer (72) comprises an excess of heat-sealing material which is connected or is suitable for connecting with the opposite second adhesive layer (72) or first adhesive layer (71) in correspondence with at least one section of the perimeter edge (63) of the conductive layer (59) insulating it.26) Joining element according to claim 25 characterized in that the first adhesive layer (71) comprises, at least on the outside, self-adhesive material of the pressure-sensitive type, or chemically activated, or of another type suitable for labels, coinciding with, or distinct from, the heat-sealing material.27) Joining element according to claim 26 characterized in that it is in the form of a label, provided on release liner from which it is removable.28) Joining element according to any one of claims 25 to 27 characterized in that said excess of heat-sealing material of the first adhesive layer (71) and / or of the second adhesive layer (72) extends beyond the perimeter of the respective first face (61) or second face (62) in correspondence with said at least one section of the perimeter edge (63).29) Joining element according to claim 28 characterized in that both the first adhesive layer (71) and the second adhesive layer (72) extend with respectiveexcesses beyond the perimeter of the respective first face (61) or second face (62) and are mutually welded in correspondence with said at least one section of the perimeter edge (63).30) Joining element according to any one of claims 25 to 29 characterized in that the heat-sealing material comprises one or more additives selected from metallocenes, ethylene acrylic acid copolymer (EAA), hyperbranched polymers (HBP), plasticizers, or other similar materials.31) Machine for manufacturing a sheet material (51) according to any one of claims 1 to 10, characterized in that it comprises: means for fixing the joining elements (57) to the support means (52) at the respective welding portions (55), suitable for making the first adhesive layer (71) adhere to the support means (52); means for connecting the excess of heat-sealing material of the first (71) and / or second (72) adhesive layers to the opposite adhesive layer (72, 71) in correspondence with the at least one section of the perimeter edge (63), insulating it.32) Machine according to claim 31 characterized in that the machine is of the labeling machine type, the joining elements (57) being in the form of a label, and further comprises means for picking the joining elements (57) from their release liner and means for depositing or pressure applying each joining element (57) at a respective welding portion (55) of the support means (52).33) Machine according to claim 31 or 32 characterized in that the means for connecting the excess of heat-sealing material comprise heating means by contact, hot air, electromagnetic induction, or the like.34) Machine according to any one of claims 31 to 33 characterized in that themeans for connecting the excess of heat-sealing material further comprise pliers or press means for compressing the excess of heat-sealing material, perpendicularly to the joining element (57).

Images