WO2015132769A1

WO2015132769A1 - Sealed inner package provided with an exhaust hole regulated by an exhaust valve, multilayer sheet of packing material, and method of producing a multilayer sheet of packing material

Info

Publication number: WO2015132769A1
Application number: PCT/IB2015/051657
Authority: WO
Inventors: Simone PASQUI; Roberto Polloni; Claudio PISI; Stefano Negrini
Original assignee: G.D Societa' Per Azioni
Priority date: 2014-03-06
Filing date: 2015-03-06
Publication date: 2015-09-11
Also published as: DE112015001122T5; DE112015001122B4; PL418679A1; PL231420B1; WO2015132769A8

Abstract

Package (1) having: a group (4) of articles; a sealed inner package (3), which encloses the group (4) of articles, has an article extraction opening (5) and is formed from a sheet (14) of heat-sealable packing material which is folded about the group (4) of articles and stabilized by heat-sealing; at least one exhaust hole (18), which is formed through a wall of the sealed inner package (3) to exhaust part of the air from, and depressurize, the sealed inner package (3) itself; and an exhaust valve (19) which is superimposed over the exhaust hole (18) and has at least one valve element (20), which is movable between a closed position in which it seals the exhaust hole (18) and isolates the exhaust hole (18) from the outside atmosphere and an open position in which the exhaust hole (18) communicates freely with the outside atmosphere.

Description

"PACKAGE WITH A SEALED INNER PACKAGE PROVIDED WITH AN EXHAUST HOLE REGULATED BY AN EXHAUST VALVE, MULTILAYER SHEET OF PACKING MATERIAL, AND METHOD OF PRODUCING A MULTILAYER SHEET OF PACKING MATERIAL"

TECHNICAL FIELD

The present invention relates to a package with a sealed inner package provided with an exhaust hole regulated by an exhaust valve, to a multilayer sheet of packing material, and to a method of producing a multilayer sheet of packing material.

In the following description, reference will be made, for brevity, to a rigid packet of cigarettes with hinged lid and housing a sealed inner package without loss of generality in reference to the present invention.

PRIOR ART

In Figure 1 a sealed inner package A known and described in detail in the patent application US2006228057A1 is illustrated. Said sealed inner package A is provided with an extraction opening B to extract the items contained inside the sealed inner package A and with an exhaust hole C, which is formed through a wall of the sealed inner package A for exhausting part of the air from, and depressurizing the sealed inner package A, and is coupled to an exhaust valve D.

As shown in Figure 2, the exhaust valve D is initially carried by a tape E wound in a reel and is drawn from the tape E to be applied to the wall of the sealed inner package A at the exhaust hole C.

As shown in Figure 3, the exhaust valve D comprises a support layer F which is permanently glued to an underlying sheet of packing material G which constitutes the wall of the sealed inner package A and an active layer H which is superimposed on and glued to the support layer F. In the active layer H a valve element is defined, which is movable between a closed position in which it seals the exhaust hole C and isolates the exhaust hole C from the outside atmosphere and an open position in which the exhaust hole C communicates freely with the outside atmosphere; in particular, the valve element is defined by a portion of the active layer H which is separated from the rest of the active layer H by a U-shaped through incision (better illustrated in Figure 1) and is connected to the underlying inner layer by means of an adhesive element.

The exhaust valve D described in patent application US2006228057A1 must be separated from the tape E, and then applied (with some precision in order to be correctly aligned with the exhaust hole C) to the sheet of packing material G that defines the sealed inner package A immediately before or after folding the sheet of packing material G; accordingly, in the packing machine forming the sealed inner package A it is necessary to provide for the presence of a labeling station in which each exhaust valve D is separated from the tape E and then applied (with extreme precision) to the corresponding sheet of packing material G. However, the presence of said labeling station may be problematic in an existing packing machine, since it is complex to find the necessary space for the labeling station itself; in this regard it is well to note that the labeling station requires the presence of a feeding unit of the tape E and that must support the corresponding reel, and the devices for changing the reel itself, and that the labeling station must also provide a drying zone wherein the glue between the support layer F of the exhaust valve D and the underlying sheet of packing material G has time to consolidate to achieve a sufficient degree of adhesion for preventing an undesired detachment of the exhaust valve D itself during subsequent handling of the sheet of packing material G.

Furthermore, the fact of having to cyclically feed the reels, whereon the tapes E bearing the exhaust valves D are wound, to the packing machine, constitutes a logistics complication of the packing machine with an evident increase of the overall production costs.

The patent application EP0559598A1 describes a multilayer sheet of packing material used for producing a sealed inner package and is provided with an exhaust hole to exhaust part of the air from the sealed inner package and with an exhaust valve which is superimposed over the exhaust hole.

DESCRIPTION OF THE INVENTION

The object of the present invention is to provide a package with a sealed inner package provided with an exhaust hole regulated by an exhaust valve, a multilayer sheet of packing material, and a method of producing a multilayer sheet of packing material, said package, multilayer sheet of packing material and method for producing a multilayer sheet of packing material are free of the drawbacks described above and are, at the same time, easy and inexpensive to manufacture.

According to the present invention, a package with a sealed inner package provided with an exhaust hole regulated by an exhaust valve, a multilayer sheet of packing material, and a method of producing a multilayer sheet of packing material, as claimed in the appended claims are provided.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described with reference to the accompanying drawings, which illustrate a non-limitative embodiment, wherein:

Figure 1 is a perspective view of a known sealed inner package that is part of the state of the art and is provided with an exhaust hole regulated by an exhaust valve;

- Figure 2 is a perspective view of a known tape that is part of the state of the art and supports a series of exhaust valves of the type illustrated in Figure 1 ;

Figure 3 illustrates two sectional views of the known exhaust valve illustrated in Figure 1 in a closed position and in an open position of the exhaust hole respectively;

- Figure 4 is a front perspective view and in a closed configuration of a packet of cigarettes produced according to the present invention and comprising a sealed inner package provided with an exhaust hole regulated by an exhaust valve;

Figure 5 is a front perspective view of the packet of cigarettes of Figure 4 in a partially open configuration;

Figure 6 is a front perspective view of the packet of cigarettes of Figure 4 in a fully open configuration;

- Figure 7 is a front perspective view of the sealed inner package of the packet of Figure 4;

- Figure 8 is a front perspective view of a group of cigarettes contained inside the sealed inner package of Figure 7;

Figure 9 is a front perspective view of a stiffener contained inside the sealed inner package of Figure 7;

- Figure 10 is a plan view of a multilayer sheet of packing material used to form the sealed inner package of Figure 7;

- Figures 11 and 12 are two different sectional views of an exhaust hole and of a corresponding exhaust valve formed in the multilayer sheet of packing material of Figure 10 in a closed position and an open position of the exhaust hole respectively;

- Figure 13 is a sectional and exploded view of the multilayer sheet of packing material of Figure 10 at the exhaust hole and at the corresponding exhaust valve of Figures 11 and 12; and - Figure 14 is a plan view of the multilayer sheet of packing material of Figure 10 highlighting two different types of adhesive interposed between two layers of the multilayer sheet of packing material itself. PREFERRED EMBODIMENTS OF THE INVENTION

Figures 4, 5 and 6 the number 1 indicates as a whole rigid packet of cigarettes. The packet 1 of cigarettes comprises an outer container 2 made of cup-shaped cardboard or rigid paperboard and a sealed inner package 3 (better illustrated in Figure 7) housed inside the container 2. The sealed inner package 3 encloses a group 4 of cigarettes (shown in Figure 8) having a parallelepiped shape and a top cigarette extraction opening 5. The cigarette extraction opening 5 affects the entire top portion of the inner package 3 and the inner package 3 is provided with a tear strip 6 which allows to eliminate a top portion of the sealed inner package 3 to free the extraction opening 5; in other words, at the first opening of the packet 1 of cigarettes the user pulls the tear strip 6 to remove a top portion of the sealed inner package 3 and thus free the extraction opening 5. According to an alternative embodiment not illustrated, the extraction opening 5 is centrally arranged, is closed by an "open & close" type sealing flap and affects a portion of a front wall of the sealed inner package and a portion of a wall top of the sealed inner package.

The outer container 2 has an open top end 7 and is provided with a cup-shaped lid 8 hinged to the container 2 along a hinge 9 to rotate, with respect to the container 2, between an open position (illustrated in Figures 5 and 6) and a closed position (illustrated in Figure 4) of the open top end 7.

The lid 8, when in its closed position, gives the outer container 2 a rectangular parallelepiped shape having a top wall and a bottom wall parallel and opposite to each other, a front wall and a rear wall (in which the hinge 9 is formed) parallel and opposite to each other, and two side walls which are parallel and opposite to each other. Between the side walls and the front and rear walls four longitudinal edges are defined, while between the upper and lower walls and the of front, rear and lateral walls eight transverse edges are defined . As shown in Figure 9, the sealed inner package 3 comprises a stiffener 10, which is made of cardboard or rigid paperboard (quite similar to the cardboard or rigid paperboard constituting the outer container 2), is U-shaped and is arranged inside the sealed inner package 3 contacting the group 4 of cigarettes. The stiffener 10 comprises a front wall 11 of substantially rectangular shape, which is arranged contacting a front wall of the group 4 of cigarettes and a pair of lateral walls 12, which are connected to the opposite sides of front wall 11 and are arranged contacting the lateral walls of the group 4 of cigarettes. The front wall 11 has a window which is arranged at the top, is delimited by an edge 13, is U-shaped, and facilitates the extraction of the cigarettes from the group 4 of cigarettes as it leaves exposed a top area of the front wall of the group 4 of cigarettes.

The function of the stiffener 10 is to give greater stiffness and greater shape to the sealed inner package 3 in order to prevent the same sealed inner package 3 from collapsing on itself after removing a part of the cigarettes contained inside the sealed inner package 3 itself, thus complicating the extraction of the remaining cigarettes. An additional function of stiffener 10 is to provide a suitable mechanical protection for the cigarettes during formation and handling of the sealed inner package 3. Finally, another function of the stiffener 10 is to keep the lid 8 in the closed position, as the lid 8 passes from the closed position to the open position (and vice versa) it must slightly deform in an elastic way the top and front of the stiffener 10.

As illustrated in Figure 10, the sealed inner package 3 is obtained by folding a sheet 14 of heat-sealable packing material, which has a rectangular shape, is folded about the group 4 of cigarettes enclosed in the stiffener 10 and once folded is stabilized by heat-sealing (i.e. overlapping portions of the sheet 14 of packing material are connected together in a stable manner by heat-sealing) .

As illustrated in Figure 7, the sealed inner package 3 comprises an exhaust hole 18, which is formed through a front wall of the sealed inner package 3 to exhaust part of the air from, and depressurize, the sealed inner package 3. In the embodiment illustrated in Figure 7, the exhaust hole 18 is formed through the front wall of the sealed inner package 3, but it is clear that the exhaust hole 18 can be formed in any other wall (top, bottom, side, back) of the sealed inner package 3; in any case, it would be preferable that the exhaust hole 18 was formed at the stiffener 10, i.e. in an area of the sealed inner package 3 that rests on the underlying stiffener 10. In fact, during the exhaust of part of the air from the sealed inner package 3, an exhaust device rests with a certain mechanical pressure on the sealed inner package 3 about the exhaust hole 18 and thus the presence of the underlying stiffener 10 at the exhaust hole 18 prevents the mechanical pressure exerted by the exhaust device from damaging the cigarettes contained inside the sealed inner package 3 (i.e. the stiffener 10 protects the cigarettes contained inside the sealed inner package 3 from the mechanical pressure exerted by the exhaust device) .

Moreover, the sealed inner package 3 comprises an exhaust valve 19 which is superimposed over the exhaust hole 18 and has the function of maintaining the exhaust hole 18 normally isolated from the outside atmosphere so as to not have any passage of gas between the sealed inner package 3 and the outside atmosphere. The exhaust valve 19 is normally closed (i.e. it normally seals the exhaust hole 18 and isolates the exhaust hole 18 from the outside atmosphere) and is temporarily open (i.e. the exhaust hole 18 communicates freely with the outside atmosphere) just and only during the exhaust step of part of the air contained inside the sealed inner package 3 to depressurize the sealed inner package 3 itself.

As illustrated in Figures 10-13, the exhaust valve 19 comprises a valve element 20, which is movable between a closed position (illustrated in Figures 11 and 13) in which it seals the exhaust hole 18 and isolates the exhaust hole 18 from the outside atmosphere and an open position (illustrated in Figure 12) in which the exhaust hole 18 communicates freely with the outside atmosphere.

As illustrated in Figures 11 and 12, the sheet 14 of packing material is a sheet of multilayer packing material and comprises an inner layer 21 of plastic material (of thermoplastic type to be heat-sealable ) and an outer layer 22 of plastic material (of thermoplastic type to be heat- sealable) superimposed and glued to each other and both extend seamlessly over the whole extension of the sheet 14 of packing material. Between the two layers 21 and 22 a permanent non- detachable adhesive 23 is interposed, as illustrated in Figure 14, extends over the whole of the sheet 14 of packing material, except for the area wherein the valve element 20 is located (i.e. with the exception of the area wherein the exhaust valve 19 is located) ; the adhesive 23 is a permanent adhesive that dries and then once dried (or shortly after its application) does not allow any separation (if not following final breakage and thereby being no longer recomposable ) between the two layers 21 and 22. In the area where the valve element 20 is located (i.e. the area wherein the exhaust valve 19 is located) , between the two layers 21 and 22 a pressure- sensitive re-stick adhesive 24 is interposed (i.e. which does not dry) which allows, even after a long time, to locally separate the two layers 21 and 22 and then to bring the two layers 21 and 22 together again for a great number of times. As shown more clearly in Figures 11, 12 and 13, the exhaust hole 18 is only formed through the inner layer 21 of the sheet 14 of packing material; i.e. the exhaust hole 18 passes through the inner layer 21 of the sheet 14 of packing material and does not affect in any way the outer layer 22 of the sheet 14 of packing material. Furthermore, the valve element 20 of the exhaust valve 19 is defined by a portion of the outer layer 22 (and only by the outer layer 22) which is separated from the rest of the outer layer 22 by a U-shaped through- incision 25 and is connected to the underlying inner layer 21 by the re-stick adhesive 24. In the embodiment illustrated in the attached figures the U-shaped through incision 25 forms a sharp angle at the cusp (as illustrated in Figure 10), but according to alternative and completely equivalent embodiments the U-shaped through incision 25 may have a rounded shape at the cusp or it could be shaped as a broken line formed by the union of multiple straight segments angled one with respect to the other.

Normally, the re-stick adhesive 24 which is located at the exhaust valve 19 keeps the valve element 20 of the exhaust valve 19 in close contact with the underlying inner layer 21 of the sheet 14 of packing material to seal the exhaust hole 18, i.e. isolating the exhaust hole 18 from the outside atmosphere (as shown in Figure 11) . When an adequate uplifting force is applied to the valve element 20 of the exhaust valve 19 (typically as a result of suction or by mechanical action) , the valve element 20 of the exhaust valve 19 is lifted from the underlying inner layer 21 of the sheet 14 of packing material (and therefore the re-stick adhesive 24 interrupts its binding action) allowing the exhaust hole 18 to communicate freely with the outside atmosphere (as shown in Figure 12) ; when the uplifting force acting on the valve 20 of the exhaust valve 19 stops, the valve element 20 is leaned back onto the underlying inner layer 21 of the sheet 14 of packing material (as shown in Figure 11 and possibly with the aid of a mechanical pressing member) determining a new closure of the exhaust valve 19 due to the binding effect of the re- stick adhesive 24.

In the embodiment described above, there is only one exhaust hole 18 of relatively large dimensions and the exhaust valve 19 has a single valve element 20 which is coupled directly to the exhaust hole 18 (i.e. superimposed over the exhaust hole 18 itself) . According to an alternative and perfectly equivalent embodiment, multiple exhaust holes 18 of smaller size are provided and the exhaust valve 19 has several valve elements 20, each of which is coupled directly to a corresponding exhaust hole 18 (i.e. superimposed over the exhaust hole 18 itself) . According to a further and perfectly equivalent embodiment, only one exhaust hole 18 of relatively large dimensions is provided and the exhaust valve 19 has several valve elements 20, each of which is arranged about the exhaust hole 18 (i.e. the valve elements 20 are uniformly distributed about the exhaust hole 18) . In the embodiment described above, the adhesive 24 which is located at the exhaust valve 19 is a pressure-sensitive re- stick adhesive (i.e. which does not dry); in this embodiment, the exhaust valve 19 is multi-purpose, i.e. may be used many times as it is possible to switch several times from the closed position to the open position and vice versa. According to an alternative embodiment, the adhesive 24 which is located at the exhaust valve 19 is an adhesive which is initially inactive and is activated by heat, i.e. an adhesive that at the first application does not cause any type of gluing between the two layers 21 and 22 of the sheet 14 of packing material and which can be activated by heating to determine a permanent gluing (i.e. no longer separable if not by permanent breakage) between the two layers 21 and 22 of the sheet 14 of packing material; in this embodiment, the exhaust valve 19 is disposable, i.e. may be used only once because once the adhesive 24 is activated by heating it is no longer possible to re-open the exhaust valve 19 itself.

As previously mentioned, the exhaust hole 18 is formed through the front wall of the sealed inner package 3 and therefore is superimposed on the front wall 11 of the stiffener 10. The stiffener 10 may be free of holes at the exhaust hole 18, because in any case, by taking in air through the exhaust hole 18, the air reaches the exhaust hole 18 by flowing in the space between the inner surface of the sealed inner package 3 and the outer surface of the stiffener 10; however, in this embodiment it is necessary to apply a greater depression to overcome the load losses generated by the "tortuous" path followed by the air inside the sealed inner package 3 for reaching the exhaust hole 18. According to a preferred embodiment illustrated in Figure 9, the front wall 11 of the stiffener 10 has a through hole 26, which is arranged at the exhaust hole 18 (i.e. aligned with the exhaust hole 18) and allows a more direct air flow from the inside of the sealed inner package 3 towards the exhaust hole 18.

According to a preferred embodiment illustrated in Figure 9 and in Figures 11, 12 and 13, around the through hole 26 of the stiffener 10 a permanent non-detachable adhesive 27 is applied which locally determines a permanent gluing between the sheet 14 of packing material and the underlying stiffener 10 (i.e. between the bottom face of the inner layer 21 of the sheet 14 of packing material and the top face of the front wall 11 of the stiffener 10) . The function of the permanent adhesive 27 is to bind the inner layer 21 of the sheet 14 of packing material to the underlying stiffener 10 at the exhaust valve 19 (i.e. around the through hole 26 of the stiffener 10) so when an uplifting force is applied to the valve element 20 of the exhaust valve 19, only the valve element 20 of the exhaust valve 19 from the underlying inner layer 21 of the sheet 14 of packing material is lifted. In other words, in the absence of the permanent adhesive 27 when an uplifting force is applied to the valve element 20 of the exhaust valve 19 the whole sheet 14 of packing material could be lifted (i.e. both the valve element 20 of the exhaust valve 19, and the underlying inner layer 21) without then determining the desired separation between the valve element 20 of the exhaust valve 19 and the underlying inner layer 21 of the sheet 14 of packing material; instead, the presence of the permanent adhesive 27 mechanically binds the inner layer 21 of the sheet 14 of packing material to the underlying stiffener 10 thus preventing the inner layer 21 of the sheet 14 of packing material from lifting and allowing the exhaust valve 19 to open properly when an uplifting force is applied to the valve element 20 of the exhaust valve 19.

According to a preferred, but not binding, embodiment, the exhaust hole 18 is formed through the inner layer 21 of the sheet 14 of packing material before bringing together the two layers 21 and 22 of sheet 14 of packing material; in the same way, the through incision 25 delimiting the valve element 20 is formed through the outer layer 22 of the sheet 14 of packing material before bringing together the two layers 21 and 22 of the sheet 14 of packing material. In this way, the performing of the exhaust hole 18 and of the through incision 25 is extremely simple and can be performed with trivial mechanical operations. It is important to note that when the two layers 21 and 22 of the sheet 14 of packing material are superimposed, a high precision in the relative positioning between the exhaust hole 18 and the through incision 25 delimiting the valve element 20 is not required in that, small deviations do not alter in any way the functionality of the exhaust valve 19. Alternatively, the exhaust hole 18 and the through incision 25 may be formed on the sheet 14 of packing material after bringing together the two layers 21 and 22; in this case, it is necessary to use a laser processing that allows to etch with extreme precision only part of the overall thickness of the sheet 14 of packing material.

The sealed inner package 3 described above has numerous advantages.

In the first place, in the embodiment of the sealed inner package 3 described above the exhaust valve 19 is from the outset already integrated in the sheet 14 of packing material and therefore it is not necessary to provide any kind of additional operation for the preparation of the exhaust valve 19 itself; in this way, the packing machine is greatly simplified (in this respect it is important to observe that the exhaust device that rests on the sealed inner package 3 around the exhaust hole 18 to exhaust part of the air from the sealed inner package 3 itself is extremely small and compact and therefore simple to install even in an existing packing machine) . Moreover, the sealed inner package 3 described above is also simple and inexpensive to produce, since the operations required to integrate the exhaust valve 19 in the layers 21 and 22 of the multilayer sheet 14 of packing material are easy to perform and do not require the use of additional materials (only the replacement of part of the adhesive 23 with the permanent re-stick adhesive 24 at the exhaust hole 18) .

In the non-limiting embodiment illustrated in the attached figures, the package of the present invention contains a group 4 of cigarettes; thanks to the numerous advantages of the package of the present invention, said package can also be used to contain articles other than cigarettes, such as food products (candies, chocolates or other sweets) .

Claims

1) A package (1) comprising:

a group (4) of articles;

a sealed inner package (3) which encloses the group (4) of articles, has an article extraction opening (5), and is made from a sheet (14) of heat-sealable packing material folded about the group (4) of articles and stabilized by heat- sealing;

at least one exhaust hole (18) formed through a wall of the sealed inner package (3) to exhaust part of the air from, and depressurize, the sealed inner package (3); and

an exhaust valve (19) superimposed over the exhaust hole (18) and comprising at least one valve element (20) movable between a closed position, in which it seals the exhaust hole (18) and isolates the exhaust hole (18) from the outside atmosphere, and an open position, in which the exhaust hole (18) communicates freely with the outside atmosphere;

wherein the sheet (14) of packing material is a sheet of multilayer packing material and comprises an inner layer (21) of plastic material and an outer layer (22) of plastic material superimposed and glued to each other by a first adhesive (23) and both extend seamlessly over the whole extension of the sheet (14) of packing material;

the package (1) being characterized in that:

the exhaust hole (18) is only formed through the inner layer (21) ; and

the valve element (20) of the exhaust valve (19) is defined by a portion of the outer layer (22) separated from the rest of the outer layer (22) by a U-shaped through incision (25) and connected to the underlying inner layer (21) by a second adhesive (24) different from the first adhesive (23) .

2) A package according to Claim 1, wherein the first adhesive (23) is a permanent non-detachable adhesive, and extends over the whole of the sheet (14) of packing material, except for the area in which the valve element (20) is located.

3) A package according to Claim 1 or 2, wherein the second adhesive (24) is a pressure-sensitive re-stick adhesive, and only extends over the area in which the valve element (20) is located.

4) A package according to Claim 1 or 2, wherein the second adhesive (24) is an initially inactive adhesive, is activated by heat, and only extends over the area in which the valve element (20) is located.

5) A package according to one of Claims 1 to 4, and comprising a stiffener (10) made of rigid material and located inside the sealed inner package (3), contacting the group (4) of articles .

6) A package according to Claim 5, wherein the stiffener (10) is located at the exhaust hole (18), so that the exhaust hole

(18) is superimposed on a wall (11) of the stiffener (10) .

7) A package according to Claim 6, wherein the wall (11) of the stiffener (10) has a through hole (26) aligned with the exhaust hole (18) .

8) A package according to Claim 7, wherein a third adhesive (27), which glues the inner layer (21) of the sheet (14) of packing material locally to the stiffener (10), is applied about the through hole (26) in the stiffener (10) .

9) A package according to Claim 8, wherein the third adhesive (27) is a permanent non-detachable adhesive and extends solely about the through hole (26) in the stiffener (10) .

10) A package according to any one of Claims 1 to 9, and comprising a rigid outer container (2) housing the sealed inner package (3) .

11) A package according to Claim 10, wherein the rigid outer container (2) is cup-shaped, and has an open top end (7); and a cup-shaped lid (8) hinged to the rigid outer container (2) along a hinge (9) to rotate, with respect to the rigid outer container (2), between an open position and a closed position opening and closing the open top end (7) respectively.

12) A sheet (14) of packing material from which to form a sealed inner package (3); the sheet (14) of packing material comprising :

an exhaust hole (18) for exhausting part of the air from, and depressurizing, the sealed inner package (3); and

the sheet (14) of packing material being characterized in that:

the exhaust hole (18) is only formed through the inner layer (21); and

13) A method of producing a sheet (14) of packing material from which to form a sealed inner package (3); the sheet (14) of packing material comprising:

an exhaust valve (19) superimposed over the exhaust hole (18) and comprising at least one valve member (20) movable between a closed position, in which it seals the exhaust hole (18) and isolates the exhaust hole (18) from the outside atmosphere, and an open position, in which the exhaust hole (18) communicates freely with the outside atmosphere; wherein the sheet (14) of packing material is a sheet of multilayer packing material, and comprises an inner layer (21) of plastic material and an outer layer (22) of plastic material superimposed and glued to each other by a first adhesive (23), and both of which extend seamlessly over the whole extension of the sheet (14) of packing material;

the method being characterized by comprising the steps of:

forming the exhaust hole (18) through the inner layer (21) only;

forming a U-shaped through incision (25) , which defines the valve element (20) of the exhaust valve (19), through the outer layer (22) only, so that the valve element (20) is defined by a portion of the outer layer (22) separated from the rest of the outer layer (22) by the through incision (25); and

depositing a second adhesive (24), different from the first adhesive (23), between the outer layer (22) and the inner layer (21), at the valve element (20) .