ITMO20110289A1 - PACKAGING, APPARATUS AND METHOD - Google Patents

Description

Packaging, apparatus and method

The invention concerns a package provided with an easy opening (so-called â € œeasy-openingâ €) realized by joining together by heat sealing two multilayer sheets and provided with a plurality of incisions made on at least one layer of the aforementioned two sheets using laser technology.

The invention also relates to an apparatus and a method for making a plurality of incisions using laser technology on one or more layers of a sheet of multilayer material, for example for packaging.

In the packaging sector, in particular in the field of flexible packaging for food products, packages with an easy opening are known - and increasingly widespread.

The packages of the known type produced with the technologies currently available are envelope-shaped or pouch-shaped packages made by joining together two sheets of multilayer material, each comprising one or more layers and forming the walls of the aforesaid package. For example, the sheets of multilayer material that form the walls of the package can each comprise three layers: an external layer of plastic material, an intermediate layer of aluminum (or barrier layer), and an internal layer of plastic material, which can also be different from the outer layer material. The multilayer sheets are welded together along the edge, for example at three sides of the perimeter, so as to leave open only one side where an opening is defined through which the product to be packaged can be introduced inside of the packaging. Once the package is filled, the multilayer sheets are also sealed on the side of the mouth so as to close the package.

Packages of known type can comprise one or more lines of intended opening which are weakening lines in which material is removed from one or more layers of the multilayer sheet.

In particular, these lines of intended opening can be obtained by means of mechanical removal means, for example abrasive means, which make incisions in the outermost layer of the multilayer sheet. The incisions can be through or they can only partially affect the thickness of this layer.

These incisions extend across the entire width of the package so as to join two opposite sides of the package. The incisions are made in a portion of intended opening close to the mouth of the package. On the two opposite sides between which the aforesaid incisions extend, two notches are made - one for each side - which act as opening promoting means. A user can in fact open the package by acting on a notch from which the tear then spreads along the incisions made in the aforementioned intended opening portion.

A disadvantage of known packages bearing the aforementioned incisions is that their aesthetic appearance is ruined since these incisions substantially appear as if they were damage suffered by the material that forms the package. This is very serious if you think that it can induce the consumer not to buy the package because he can doubt the conservation quality of the product contained in it.

Furthermore, in the case of printed materials, the aforementioned engravings affect the quality of the print subject and in some cases the legibility of the parts including wordings or writings. Again, a disadvantage of the apparatuses for making such packages of a known type is that they have significantly high maintenance costs.

It is also known to make one or more incisions, parallel and spaced apart, by laser technology on a layer of a multilayer sheet in order to create engraving lines that define a tear strip that can be removed by the user for opening. of the package and that extend over the entire depth of the engraved layer.

It is therefore also known a method for laser engraving a multilayer package with two rectilinear and parallel incisions that define a tear strip that can be removed by the user to open the package. The incisions are spaced a certain distance in such a way as to have a tear stripe wide enough to allow the package to be opened.

Furthermore, in the known art, the adjacent incisions made with laser technology cannot be too close to each other since otherwise the power density - i.e. the energy per unit of surface - is too high and localized fusions of the material. This is to be avoided because it can compromise both the opening of the package and its aesthetics.

A disadvantage of the apparatuses and methods that use the laser technologies currently available to achieve an easier opening of the package is that a linear (for example substantially horizontal) and homogeneous tearing of the package is not guaranteed. Consequently, the known types of easy-opening packages made with laser technology have an ineffective opening as the tearing of the sheet can spread in an uncontrolled manner and a considerable force is also required from the user to open the package.

This is a serious disadvantage if we consider that currently consumers and the market increasingly require that the packages meet certain aesthetic and functional requirements, among which precisely that the opening of the package takes place through a substantially straight tear - to avoid an uncontrolled opening and consequent spillage of the contained product - and that the package can be opened easily by a user exerting a reduced force.

Another disadvantage of laser apparatuses and methods that use laser technologies currently available is that they are not very flexible as it is not possible to adjust the operation of the apparatus according to the type of incisions to be obtained and the type of packaging. processing.

Packages with easy opening are also known made by joining two multilayer sheets which form the walls and without the intended opening lines. In these packages, one or more layers of material of each of the two multilayer sheets are made of a (known) polymeric material whose molecule chains are all substantially oriented in the same direction, which then becomes the direction in which a user can open the packaging. The opening of the package is therefore guaranteed by the presence of the so-called mono-oriented polymeric layer, which must have a considerably greater thickness than the other layers that form the package in order for the latter to open correctly.

A disadvantage of this type of packaging without clear lines of understanding is that there is no guarantee that the opening of the package will take place in a linear and rectilinear manner, which can compromise the aesthetic appearance of the package itself.

Furthermore, another disadvantage of these packages is that they have the limit that the thicknesses of the layers that form the multilayer sheets must respect very precise reciprocal proportions so that the thickness of the mono-oriented layer is much greater than the sum of the thicknesses of the other layers. otherwise it is no longer possible to open the package.

An object of the invention is to make available an easy-opening package made with sheets of multilayer material and provided with a plurality of incisions made on at least one layer of the aforementioned sheets by means of laser technology.

A further object is to obtain economical packages which are equipped with a simple and reliable opening system.

A still further object is to ensure that the opening of the package takes place by means of a substantially rectilinear laceration.

Another object is to ensure that the package can be easily opened by a user by exerting a reduced force.

Another object of the invention is to improve known apparatuses and methods for making easy-opening packages by means of laser technology.

Yet another object is to provide a laser apparatus which allows to make a plurality of engravings on at least one layer of a sheet of multilayer material, for example for packaging.

A still further object is to provide a method for making a package provided with a plurality of engravings made by laser technology.

According to the invention, a package as defined in claim 1 is provided.

According to the invention, an apparatus as defined in claim 10 is also provided.

According to the invention there is also provided a method as defined in claim 17.

The invention can be better understood and implemented with reference to the attached drawings, which show an exemplary and non-limiting form of implementation, in which:

Figure 1 is a perspective view of an easy-opening package according to the invention;

Figure 1a is an enlargement of a detail of Figure 1; Figure 1b is a version of the enlargement of Figure 1a;

Figure 2 is a top plan view of the package of Figure 1;

Figure 3 is a partial and enlarged schematic cross-section of the package of Figure 1 according to the section line III-III of Figure 2;

Figure 4 is a schematic perspective view of a laser apparatus for making incisions on the package of Figure 1. With reference to Figures 1 to 3, an easy-opening package 1 is shown, made by joining together two sheets of multilayer material 15 by heat sealing. flexible. The sheets 15, which define the walls of the package 1, are joined along respective edges to form the package 1 shaped as an envelope or pouch. In particular, the sheets 15 are joined along two lateral edges 8, 9, an upper edge 10 in correspondence with which a mouth area of the package 1 is defined, and a bottom edge 7 â € “also called â € œbaseâ € - which can allow package 1 to remain in a vertical position when resting on a surface. The package 1 according to the invention is therefore a package of the so-called â € œstand-upâ € type, which remains in a vertical position when it is resting on a horizontal plane.

It is understood that the teachings of the present invention can also be used to produce packages other than the aforesaid type, in particular also shaped packages such as envelopes, which therefore are unable to remain in a vertical position when resting on a surface. As can be seen from the section of Figure 3, each sheet of multilayer material 15 can comprise, for example, three layers which are joined together by adhesive layers interposed between them. In particular, the version shown comprises in sequence (from the outside towards the inside) an external layer 2 in polyester, an adhesive layer 3 (for example resin or similar), a layer 4 made with a material having waterproof characteristics almost total gas and / or water vapor (such as by way of example but not limited to: aluminum, EVOH, PVDC etc.) and for this reason called `` barrier layer '', another adhesive layer 5, and a layer interior 6 made with one or more types of polypropylene (PP).

The outer layer 2 can have a thickness between 3 and 36 microns, the barrier layer 4 can have a thickness between 3 and 45 microns and the inner layer 6 can have a thickness between 12 and 200 microns, preferably between 50 and 80 micron.

In a version not shown, each multilayer sheet 15 can comprise only two layers, being, for example, devoid of the barrier layer 4.

In another version, not shown, each multilayer sheet 15 can instead comprise four layers, in which one of the internal layers is a â € œbarrier layerâ € and the other internal layer is made of a material that gives better mechanical characteristics to packaging such as, by way of example but not limited to, polyamide.

In a further version not shown, the number of layers that make up each multilayer sheet 15 can be further greater (by four) to give specific characteristics to the package.

In a further version not shown, the two sheets 15 that make up the package 1 can have different layers from each other, both in terms of number and composition.

In another version not shown, the inner layer 6 of each of the two sheets 15 that form the package 1 can be made of a polymeric material with high rigidity, where rigidity is understood to mean that intrinsic property of the material defined as the measurement of the resistance offered by an elastic body to deformation and bending.

Examples of these highly rigid materials can be: polyester, PVC, cellophane, polystyrene, polycarbonate, as well as various types of mono-oriented and bi-oriented polypropylene, various types of mono-oriented and bi-oriented polyethylene in which the orientation of the molecules in at least one direction is substantially parallel to the direction defined by the upper edge 10.

The inner layer 6 made of a highly rigid polymeric material (generally the aforementioned mono-oriented and / or bi-oriented polypropylene and polyethylene) is particularly advantageous if the thickness of the inner layer 6 is less than or equal to 70 micron. In fact, when the layers 2, 4, 6 that form the sheets 15 have a reduced overall thickness, it is preferable that the outer layer 6 is made with one of these materials, which - thanks to the high rigidity - confers good mechanical and structural properties to the packaging 1.

On each of the two lateral edges 8, 9 of each sheet 15 there is a notch 11 near the upper edge 10, for example shaped in the shape of a â € œVâ €. The two notches 11 are made in an opening portion 14 of the package 1 in suitable positions of the lateral edges 8 and 9 in such a way that they are substantially facing each other. The opening portion 14 is defined near the mouth of the package 1, ie near the upper edge 10.

In a version not shown, the opening portion 14 (and therefore the notches 11) can be defined in any other area of the sheets 15, for example in a median area (substantially equidistant from the upper edge 10 and from the bottom edge 7) or near the bottom edge 7.

In the opening portion 14 between the notches 11 extends a plurality of incisions 12 (Figures 2 and 3) substantially parallel to the upper edge 10. In the version shown, the plurality of incisions 12 comprises seven mutually parallel incisions, which are generally hardly visible to the eye naked on the packaging 1.

As better visible from the enlargement of Figure 1a, the tip of the â € œVâ € of the notch 11 faces the plurality of incisions 12, and in particular is located in correspondence with any incision of the plurality of incisions 12 in so that the notch 11 is aligned with an incision 12 (as shown by the dashed line in Figure 1a).

Thanks to the alignment between the tip of the â € œVâ € of the notch 11 and one (any) incision of the plurality of incisions 12, it guarantees that the opening of the package takes place in a substantially straight line with a limited force exerted by the user.

The opposite notches 11 on the two lateral edges 8, 9 can face two opposite ends of the same incision 12, but also to different incisions 12, for example to two adjacent incisions. Also in this case the opening of the package takes place in a substantially straight line and requiring a reduced force from the user.

In the same way, the notches 11 made on the two sheets 15 to be coupled together can face the same incision 12, but also to different incisions, for example to two adjacent incisions.

The enlargement of Figure 1b shows a version of the package 1 in which some incisions 12 and the notches 11 made on the two sheets 15 forming the package 1 are not in exactly corresponding positions. In fact, the plurality of engravings 12 and the notches 11 of the rear sheet 15 (shown with broken lines) are slightly displaced with respect to those of the front sheet 15, as evidenced by the arrows F.

In general, the plurality of engravings 12 can comprise between two and eleven engravings.

The adjacent incisions 12 can be spaced apart by a distance d comprised between 30 microns and 10 mm, in particular between 50 microns and 1.3 mm.

The incisions are made in the outer layer 2 and affect its entire thickness. In other words, the maximum depth of the incision is substantially equal to the thickness of the outer layer 2.

The incisions 12 made on the outer layer 2 (visible to the user) make it possible not to weaken the layers 6, 4 of the package itself - which give it the desired mechanical and structural properties, in particular if the inner layer 6 is made with a highly rigid material such as those listed above - while not damaging its aesthetic appearance.

In a version of the invention not shown, the incisions 12 only partially affect the thickness of the outer layer 2.

In a version of the invention not shown, the plurality of engravings 12 can be made on the inner layer 6 of both of the above multilayer sheets 15, ie on the inner layer 6 in contact with the product 13. Similarly to the version shown, also in this version the incisions 12 can be a number between two and eleven and can extend in depth for the whole thickness of the inner layer 6, or only for part of it. In this case, the inner layer 6 is not made with one of the highly rigid materials listed above.

In another version of the invention not shown, the incisions 12 can be made both on the outer layer 2 and on the inner layer 6 and also in this case they can extend for the entire thickness of these layers, or only for a part of it.

In a further version of the invention not shown, the package 1 may include incisions 12 made on the outer layer 2 of one of the two sheets 15, and other incisions 12 made on the inner layer 6 of the other sheet 15. In another version of the invention not shown, the incisions 12 can be made only in one of the two sheets 15 that form the package 1 (or on its outer layer 2, or on its inner layer 6).

An advantage of the invention is that of making available a package 1 with easy opening provided with a plurality of incisions 12 made on at least one layer 2, 6 by means of laser technology.

Another advantage is that of having an effective opening of the package 1 thanks to the presence of a plurality of incisions 12 which extend parallel to each other at an extremely reduced mutual distance. This allows the package 1 to be opened easily even if the incisions 12 or the notches 11 made on the two multilayer sheets 15 are not exactly facing each other. In this case, in fact, the tearing of the multilayer sheet 15 propagates starting from the notches 11 along the incisions 12 of the two coupled sheets 15 closest to the notches 11. This is possible thanks to the extremely reduced distance d between the incisions 12, which so that the notches 11 are substantially always almost aligned with one of the incisions 12. Moreover, thanks to the reduced distance d at least one of the incisions 12 made on a multilayer sheet 15 is always substantially superimposed on at least one of the incisions 12 of the other multilayer sheet 15 joined to the aforementioned sheet. Furthermore, even if the remaining incisions 12 of a sheet 15 were not superimposed on the corresponding incisions 12 of the other sheet 15 coupled to it, they would still be mutually offset by a minimum distance, which does not affect the linear propagation of the opening nor on the force that the user must exert. Thanks to this, an easy opening of the package 1 is obtained, and pleasant from the aesthetic point of view, even if the tear propagates along an incision 12 of a multilayer sheet 15, and along another incision (not superimposed on the above incision) of the other multilayer sheet 15 joined to the above sheet.

A further advantage is that the opening of the package 1 occurs substantially in a linear manner along the direction in which the incisions 12 extend, which therefore do not damage the aesthetic aspect or the functional characteristics of the package 1. This It is possible thanks to the distance d, which being so small means that even if the tear propagates passing from an incision 12 to an incision adjacent to it, this is not visible to the naked eye. Thanks to this, in an initial phase of the opening, the laceration passing from the notch 11 to one of the incisions 12 closest to it does not differ from a linear trend in an appreciable way to the naked eye.

Another advantage is that package 1 is cheap and easy to open, without the user having to apply considerable force to open it.

Another advantage is that the 12 incisions allow to obtain an easy opening of the package without compromising its hermetic seal.

Another advantage is that the incisions 12 do not damage the aesthetic appearance of the package 1, which is not damaged even once it is opened. The area in which the tear propagates is in fact substantially free from significant surface defects.

Note that in the version in which the package 1 includes an internal layer 6 made of highly rigid material (for example a mono-oriented polymer), the force required by the user to open the package 1 is even lower precisely because , while the easy opening of the pack 1 is in any case guaranteed by the plurality of engravings 12, the pack - which in this case can have very reduced overall thicknesses of the sheets 15 - has improved mechanical and structural properties.

The plurality of engravings 12 is made by means of an apparatus 20, shown in Figure 4 and described below, operating with laser technology.

The apparatus 20 comprises an optical group 21 provided with a plurality of elements of a known type and therefore not described here in detail and arranged to receive at least one main laser beam 30. The latter can come directly from a laser source (not shown ) or it can be obtained by splitting in turn a laser beam coming from a source.

The optical group 21 comprises diffractive means 28 of a known type (schematized in Figure 4 as a plurality of lenses) for dividing the main laser beam 30 into a plurality of laser beams 31. The optical group 21 is assembled in such a way as to allow a rapid change of the arrangement of the optics of the diffractive means 28 by an operator so as to consequently modify the mutual distance d between two adjacent incisions 12 and at the same time modify the number of laser beams 31 into which the main laser beam is divided 30.

The diffractive means 28 are associated with a diffractive element 22 of said optical group 21 which is shaped like a drawer and received in a housing 23 made in said optical group 21 having a shape complementary to the diffractive element 22. The housing 23 it can receive - one at a time - a plurality of diffractive elements 22 which are interchangeable with each other (one of which is shown already inserted in the optical group 21 in Figure 4), each of these elements being provided with respective diffractive means 28. The operator can then quickly connect and disconnect the diffractive element 22 inside the housing 23 by choosing each time the diffractive element 22 equipped with the diffractive means 28 which allow to obtain the number of beams 31 desired.

Furthermore, the optical group 21 comprises adjustment means 24 acting on the arrangement of the optics of the diffractive means 28 so as to vary the mutual distance (linear and / or angular) between the aforementioned laser beams 31 exiting from the optical group 21. In particular, the adjustment means 24 comprise an adjustable element 25, for example a knurled ring nut, provided with a graduated scale for reading so that the operator can precisely set the desired distance between the laser beams 31 simply by rotating this element as indicated by arrow R.

Downstream of the optical group 21, the latter is associated with a focal group 26 arranged to focus the aforementioned laser beams 31 coming out of the optical group 21. The focal group 26 typically comprises only one lens 27. The lens 27 can have a focal distance between approximately 2.5 cm and 12.5 cm.

Thanks to the lens 27, from the focal group 26 come out focused beams 32 endowed with an adequate power density which will then engrave the sheet layer 15 in an almost point-like manner to make the incisions 12. The focal group 26 can be adjusted in such a way as to obtain the most suitable focusing of the laser beams 31 according to the engraving being carried out. To do this, it is possible to move and / or rotate the lens 27, or, alternatively, to move the focal group 26 so as to bring it closer to and / or away from the multilayer sheet 15 being processed by an appropriate amount along the direction indicated by the arrow. TO.

In a version not shown, the focal group 26 comprises a plurality of lenses.

In Figure 4, for reasons of clarity only three laser beams 31 and as many focused beams 32 are shown. The apparatus 20 can however operate in such a way as to obtain a number of focused beams 32 between two and eleven. For example, to make the package 1 shown in Figures 2 and 3 having seven incisions, the apparatus 20 is configured in such a way as to emit, downstream of the focal group 26, seven focused beams 32 which, incising the outer layer 2 of the multilayer sheet 15, make the seven incisions 12.

Both the optical group 21 and the focal group 26 can comprise connections (not shown) for the introduction of air and / or inert gas inside them in order to protect the optics.

The apparatus 20 can be included in an automatic machine, not shown, arranged along the processing line that makes the package 1.

In particular, the automatic machine can be a cutting machine which receives the continuous multilayer sheet unwound from a reel at its input and cuts it to form the walls that will form the package 1 once they are heat-sealed together along the edges. The incisions 12 are made in suitable positions of the continuous multilayer sheet before the machine cuts the sheet.

Alternatively, the automatic machine can be a laminating machine, which couples together the two multilayer sheets 15 previously cut by the cutting machine so as to form the package 1. In this case the apparatus 20 makes the incisions 12 on each of the two multilayer sheets 15 in suitable positions so that corresponding incisions on the two coupled sheets 15 are substantially facing each other once the package 1 is formed.

The operation of the apparatus 20, which is also the subject of the present invention, is described below.

Before operating the apparatus 20, depending on the number of incisions 12 to be made on the outer layer 2 (or on the inner layer 6), the operator inserts the diffractive element 22 having the ™ suitable optics to allow the diffractive means 28 to divide the main laser beam 30 into the desired number of laser beams 31.

Furthermore, according to the desired distance between two adjacent incisions 12, the operator acts on the adjustment means 24 (in particular on the graduated ring 25) to set the exit distance of the laser beams 31.

Subsequently, the operator positions the focal group 26 in a defined configuration, either by adjusting the position of the lens 27, or by moving the focal group 26 along the direction A.

At this point it is possible to operate the apparatus 20, thus obtaining the desired number of focused beams 32 (at the desired distance from each other) starting from a single main laser beam 30.

An advantage to the invention is that of making available an apparatus 20 and a method which allow to make incisions 12 on a layer 2, 6 of a flexible multilayer sheet 15, in particular for packaging.

Another advantage is that the apparatus 20 can be adjusted quickly and easily by an operator by selecting the suitable diffractive element 22 and suitably adjusting the adjustment means 24, 25.

In this way, the operator can obtain a desired number of focused laser beams 32 between two and eleven spaced by a desired distance from each other between 30 microns and 10 mm, in particular between 50 microns and 1.3 mm.

A further advantage of the apparatus 20 is the fact that it also allows to effectively control the power per unit of sheet surface of the focused laser beams 32 so as not to locally melt the etched layer 2, 6 and to control at the same time the depth of the incisions 12.

Yet another advantage of the apparatus 20 is the fact that, being able to make a plurality of incisions 12 very close and parallel to each other (as mentioned, up to eleven incisions separated from each other by 30 microns), it also allows to compensate for any position tolerances between the incisions of the two mutually coupled sheets, as well as any position tolerances of the notches 11, in order to guarantee an easy opening of the package.

A further advantage is that the apparatus 20 is economical since it can operate with a very low energy expenditure (necessary for the laser to make the engravings 12) and does not require frequent and expensive maintenance interventions. Variations and / or additions to what has been described above and / or what is shown in the attached drawings are also possible.

Claims (20)

CLAIMS 1. Package (1) with easy opening formed by joining together two multilayer sheets (15) along respective edges (7, 8, 9, 10) so that said sheets (15) form the walls of said package (1), said sheets multilayer (15) each comprising at least one outer layer (2) and one inner layer (6); said package (1) comprising on at least one of said sheets (15) an opening portion (14) in which at least one notch (11) is made on at least one of said respective mutually opposite edges (8, 9), said package (1) being characterized by the fact that it is provided with a plurality of substantially straight, continuous and / or discontinuous incisions (12), parallel to each other and made by a laser beam on said outer layer (2) and / or on said layer internal (6), and that the number of said incisions (12) and their mutual distance (d) are such that said notch (11) is always almost aligned with at least one incision of said plurality of incisions (12) . Package according to claim 1, wherein said distance (d) is comprised between 0.03 mm and 10 mm, in particular between 0.05 mm and 1.3 mm. Packaging according to claim 1, or 2, wherein said plurality of incisions comprises a number of incisions (12) comprised between two and eleven, in particular between five and nine. Packaging according to one of the preceding claims, wherein said edges (7, 8, 9, 10) comprise two side edges (8, 9), an upper edge (10) and a bottom edge (7); said opening portion (14) being defined in proximity of said upper edge (10). 5. Packaging according to claim 4, wherein on each of said lateral edges (8, 9) in correspondence with said opening portion (14) there is a notch (11) in a suitable position of said lateral edges (8, 9) in such a way that said notches (11) are substantially aligned with each other. Packaging according to claim 5, wherein said plurality of incisions (12) extends into said opening portion (14) between said notches (11) substantially parallel to said upper edge (10) and to said bottom edge (7) . Packaging according to one of claims 1 to 6, wherein said incisions (12) have a maximum depth equal to the thickness of said outer layer (2) and / or said inner layer (6). Packaging according to one of the preceding claims, in which said plurality of incisions (12) and said at least one notch (11) are made in the respective opening portions (14) of said two multilayer sheets (15) joined together to form said easy-opening packaging (1). Packaging according to one of the preceding claims, in which said inner layer (6) is made of a highly rigid material, selected from a group comprising: polyester, PVC, cellophane, polystyrene, polycarbonate, various types of mono-oriented polypropylene and bi-oriented, various types of mono-oriented and bi-oriented polyethylene in which the orientation of the molecule chains in at least one direction is substantially parallel to the direction defined by said upper edge (10). 10. Apparatus (20) for making a plurality of incisions (12) on one or more layers (2, 6) of a sheet of multilayer material (15) comprising: - an optical group (21) provided with diffractive means (28) arranged to divide a main laser beam (30) entering said optical group (21) into a plurality of laser beams (31); - a focal group (26) provided with one or more lenses (27) arranged to focus said plurality of laser beams (31) entering said focal group (26) to obtain a plurality of focused beams (32); characterized in that said optical group (21) comprises adjustment means (24) acting on the arrangement of said diffractive means (28) so as to vary a mutual distance between said plurality of laser beams (31) leaving said optical group (21 ). 11. Apparatus according to claim 10, wherein said adjustment means (24) comprises an adjustable element (25) provided with a graduated scale for reading which can be rotated to adjust said mutual distance. Apparatus according to claim 10, or 11, wherein said diffractive means (28) are associated with a diffractive element (22) of said optical group (21) removably received in a housing (23) made in said optical group (21) ). 13. Apparatus according to claim 12, wherein said optical group (21) comprises a plurality of said diffractive elements (22) interchangeable with each other, each provided with respective diffractive means (28), by replacing which it is possible to obtain the number of desired laser beams (31). Apparatus according to one of claims 10 to 13, wherein said focal group (26) can be moved along a direction (A) approaching, and / or away from, said multilayer material sheet (15) and / or said one or more lenses (27) can be moved and / or rotated to obtain the desired focus of said focused beams (32). 15. Apparatus according to one of claims 10 to 14, wherein said one or more lenses have a focal distance comprised between about 2.5 cm and 12.5 cm. 16. Apparatus according to one of claims 10 to 15, wherein said focal group (26) is positioned downstream of said optical group (21). 17. Method for making a plurality of incisions (12) on one or more layers (2, 6) of a sheet of multilayer material (15) comprising the steps of: - dividing a main laser beam (30) entering an optical group (21) into a plurality of laser beams (31) by means of diffractive means (28) of said optical group (21); - focusing said plurality of laser beams (31) entering a focal group (26) to obtain a plurality of focused beams (32) through one or more lenses (27) of said focal group (26); - etching one or more layers (2, 6) of said multilayer sheet (15) with said focused beams (32); characterized in that the arrangement of said diffractive means (28) is regulated by means of adjustment means (24) so as to vary a mutual distance between said plurality of laser beams (31) leaving said optical group (21). Method according to claim 17, wherein said regulator comprises rotating an adjustable element (25) provided with a graduated scale. 19. Method according to claim 17, or 18, in which it is provided to replace a diffractive element (22) of said optical group (21) to which said diffractive means (28) are associated with another diffractive element (22) interchangeable with the which respective diffractive means (28) are associated, so as to obtain the desired number of laser beams (31). Method according to one of claims 17 to 19, in which it is provided to move said focal group (26) along a direction (A) towards, and / or away from, said multilayer sheet (15) and / or moving and / or rotating said one or more lenses (27) to obtain the desired focus of said focused beams (32).