WO2009083855A2

WO2009083855A2 - Methods for compression moulding multilayered objects, and corresponding multilayered object

Info

Publication number: WO2009083855A2
Application number: PCT/IB2008/055293
Authority: WO
Inventors: Fiorenzo Parrinello; Matteo Camerani
Original assignee: Sacmi Cooperativa Meccanici Imola Societa' Cooperativa
Priority date: 2007-12-20
Filing date: 2008-12-15
Publication date: 2009-07-09
Also published as: WO2009083855A3; ITMO20070398A1

Abstract

A method comprises stages of : dispensing a multilayer dose (68, 78, 88) comprising a principal material (64) delimited by an external lateral surface (74) and a secondary material (65) which is at least partially contained within the principal material (64), the secondary material (65) having a tubular conformation; compression-moulding the multilayer dose (68, 78, 88) in order to obtain an object (73) having a multilayer wall (55).

Description

Methods and Apparatuses for compression Moulding multilayered Objects, corresponding Doses and multilayered Object.

The invention relates to methods and apparatus for compression-moulding multilayered objects, starting from dosed amounts of plastic material. The invention further concerns doses of plastic material from which it is possible to obtain multilayered objects. Finally, the invention concerns compression- moulded multilayered objects, for example preforms, containers, caps, seals, container necks and the like.

Objects of these types made of multilayer plastic material are known, comprising a layer of barrier material interposed between two layers of principal material. The barrier material can have oxygen- and/or light-barrier properties, while the principal material provides the desired mechanical and aesthetic properties.

Objects made of multi-layered plastic material can be obtained by compression-moulding a dose of plastic material which, in this case, also has a multilayer structure. For example, the multilayered dose can be shaped as a cylinder of principal material internally of which the barrier material is arranged.

The multilayer doses are usually obtained by co-extrusion, by means of an extrusion device having a plurality of conduits dispensing the principal material and the barrier material according to predetermined sequences. The plastic material exits the extrusion device in an outlet direction and is then sub-divided into doses of the desired dimensions. The doses are then moulded between a male die and a female die, mobile to one another in a moulding direction. The moulding direction is parallel to the outlet direction along which the dose exits the extrusion device. A defect of known apparatus is that the layer of barrier material must have rather complicated shapes, especially if the compression-moulded objects to be obtained have a hollow geometry, such as in the case of preforms or caps. Consequently, extrusion heads having a certain complexity are necessary, provided with equally complicated obturator systems.

WO 2005/084904 describes a multilayered dose comprising a cylinder of principal material, internally of which the barrier material is sunk. The barrier material has the shape of a hollow cylinder surrounded by the principal material both internally and externally. During compression-moulding, the barrier material forms a fold internally of the moulded object. In order that the barrier material forming the fold does not break through onto the surface of the moulded object, WO 2005/084904 teaches that the barrier material must not be excessively close to an external lateral surface of the multilayered dose. However, the doses described in WO 2005/084904 can give rise to moulded objects having non-uniform properties. It can happen that the barrier material is not correctly folded over on itself during the compression-moulding, in which case a moulded object is produced which has some zones exhibiting the barrier material correctly folded and other zones which have the barrier material in a defective shape, for example not folded-over or broken or having a non-uniform thickness. The barrier properties in the zones where the barrier material is correctly folded will therefore be different from the barrier properties in the zones in which the barrier material is defective. The prior art includes caps made of a plastic material which comprise an end wall from which a lateral wall projects. An internal surface of the lateral wall affords means for fixing the cap to a neck of a container, for example a threaded zone. A laminated disc is attached to the base wall, comprising a barrier material having oxygen-barrier properties. In use, the laminated disc directly faces the inside of the container and the barrier material prevents the oxygen present in the external atmosphere and possibly contained internally of the container itself, from flowing through the end wall of the cap. The (laminated disc is obtained by cutting a laminated sheet material and is then inserted internally of a mould, in which the plastic material for forming the cap is injected, using a technology known as "in-mould labelling". The above-described device for obtaining a cap comprising a disc having oxygen-barrier properties leads to a relevant consumption of laminated material for obtaining the disc. When the laminated material is cut from a sheet, numerous waste cuttings are generated, which remain unused. Further, the thickness of the laminated material cannot be below a certain measurement. An aim of the invention is to improve the multilayer doses of plastic material, as well as the methods and apparatus for obtaining multilayer doses of plastic material, which can be compression-moulded such as to form multi-layered objects.

A further aim is to provide methods for producing multilayered doses which are particularly simple to actuate. A further aim is to obtain multilayered objects having properties, for example barrier properties, as uniform as possible.

A further aim is to obtain, simply, compression-moulded multilayered objects comprising a principal material and a secondary material which is not present on the external surface of the object. A further aim is to provide multilayer doses having a primary material which at least partially contains a secondary material, in which the secondary material does not have to undergo excessive deformations during the forming -A-

of the moulded object.

A further aim is to provide a cap having an end wall provided with a disc element, the disc element having a multi-layered conformation which involves only limited consumption of material. In a first aspect of the invention, a method is provided which comprises stages of: dispensing a multilayer dose comprising a principal material delimited by an external lateral surface and a secondary material which is at least partially contained within the principal material, the secondary material having a tubular conformation; compression-moulding the multilayer dose in order to obtain an object having a multilayer wall; characterised in that the distance between the secondary material and the external lateral surface in the multilayer dose is less than or equal to the thickness of the multilayer wall.

In a second aspect of the invention, a multilayer dose is provided for obtaining an object, comprising a principal material delimited by an external lateral surface and a secondary material forming a tubular layer extending about an axis of the multilayer dose, characterised in that the distance between the tubular layer and the external lateral surface is less than 4 mm. Thanks to the shorter distance between the secondary material and the external lateral surface, the method of the first aspect of the invention and the dose of the second aspect of the invention enable multilayer objects to be obtained in which the secondary material is arranged uniformly along the multilayer wall, without undergoing any folding and without being subject to breakages or undesired deformations. Since the second material in the dose is arranged in proximity of the external lateral surface, when the dose is inserted internally of a mould in order to be compression-moulded, the secondary material is already in a position that is close to what will be the final position. Consequently, the secondary material does not fill the mould with a filling flow that is such as to cause deformation and breakage. The method of the first aspect of the invention and the dose of the second aspect of the invention are particularly suited to obtaining hollow elongate objects, for example preforms for containers.

In a third aspect of the invention, a method is provided which comprises a stage of compression-moulding a multilayer dose between first forming means and second forming means which are reciprocally mobile in a moulding direction, the dose comprising a body having an axis, the body including a principal material delimited by an external lateral surface and a secondary material forming a layer which is at least partially embedded in the principal material, wherein the distance between said layer and said axis is comprised between 10% and 50% of the distance between said axis and the external lateral surface, characterised in that during the compression moulding stage the moulding direction is transversal to said axis. The method of the third aspect of the invention is particularly suited for forming objects that have a limited height, for example caps for containers or trays.

Thanks to the small distance between the layer of secondary material and the axis of the dose, it can be guaranteed that the secondary material stays sunken internally of the principal material, also in the finished object which is obtained by compression-moulding the dose. In a fourth aspect of the invention, an apparatus is provided for forming multilayer doses comprising first supply means for supplying a principal material into an extrusion conduit and second supply means for supplying discrete portions of a secondary material into a flow of the principal material in the extrusion conduit, characterised in that the extrusion conduit comprises a tract having a substantially constant section followed by a diverging tract for deforming the discrete portions such as to transform each discrete portion into a concave portion embedded in the principal material.

In a fifth aspect of the invention, a method is provided for forming multilayer doses comprising stages of: supplying a principal material to an extrusion conduit having a tract with a substantially constant section followed by a diverging tract; dispensing discrete portions of a secondary material internally of a flow of the principal material into the extrusion conduit, wherein in the diverging tract the discrete portions are deformed such as to transform each discrete portion into a concave portion embedded into the principal material. Thanks to the fourth and fifth aspect of the invention, it is possible to obtain multi-layer doses in which the secondary material has a concave shape, the doses being particularly suitable for fashioning compression-moulded objects having a bottom wall and a lateral wall. The concave portions obtained in the diverging tract of the extrusion conduit can easily guarantee, during the compression moulding, that the secondary material extends both into the end wall and into the lateral wall of the moulded object.

In a sixth aspect of the invention, a multi-layer dose is provided, comprising a body including a principal material surrounding a secondary material, the secondary material having an annular edge zone adjacent to a first end of the body and a dome-shaped zone adjacent to a second end of the body, in which the distance between the annular edge zone and the first end is comprised between 5% and 50% of the distance between the first end and the second end.

The multilayer dose of the sixth aspect of the invention enables hollow objects to be obtained which are provided with an end wall and a lateral wall, for example preforms or containers, in which the secondary material extends uniformly along the end wall and along a significant portion of the base wall. The secondary material of the dome-shaped zone is positioned, during moulding, in the base wall of the moulded object, while the portion of secondary material comprised between the annular edge zone and the dome- shaped zone is arranged along the end wall. Thanks to the short distance between the annular edge zone and the first end, the secondary material can extend along almost all the length of the lateral wall.

In a seventh aspect of the invention, a multilayer dose is provided which comprises a body including a principal material and a secondary material, characterised in that the secondary material forms at least a first quantity and a second quantity which are alt least partially embedded into the principal material, the first quantity and the second quantity being separate from one another.

In an eighth aspect of the invention, a method is provided which comprises stages of: extruding a principal material; supplying, in the principal material, discrete portions of a secondary material, such as to obtain a multi-layer structure; severing multilayer doses from the multilayer structure, characterised in that the stage of severing comprises cutting the discrete portions in order to generate from each discrete portion two quantities of secondary material included in two consecutive doses. In a ninth aspect of the invention, a multilayer dose is provided which comprises a body including a principal material and a secondary material, characterised in that between the principal material and the secondary material a third material is interposed.

Thanks to the seventh, eighth and ninth aspects of the invention, very versatile doses can be obtained, which can be made suitable for a multiplicity of different applications, by specially choosing the position, the size and the geometry of the distinct quantities of secondary material and the configuration and type of the third material.

In a tenth aspect of the invention, a method is provided which comprises stages of: severing multilayer doses from a multilayer structure of plastic material exiting from a co-extrusion device in an outlet direction; reciprocally moving first forming means and second forming means in a moulding direction, such as to obtain a multilayer object from each multilayer dose, by compression moulding; characterised in that the moulding direction is transversal of the outlet direction.

In an eleventh aspect of the invention, an apparatus is provided which comprises: a coextruder device for dispensing a multilayer structure of plastic material in an outlet direction; severing means for severing multilayer doses from the multilayer structure; first forming means and second forming means which are reciprocally mobile in a moulding direction, such as to obtain a multilayer object from each multilayer dose, by compression moulding; characterised in that the moulding direction is transversal of the outlet direction. Thanks to the transversal moulding direction with respect to the outlet direction, the method and apparatus of the tenth and eleventh aspects of the invention enable a compression-moulded object to be obtained from the multilayer does in a very simple way. Indeed, not only full objects such as seals, but also hollow objects such as preforms or caps for containers can be obtained from multilayer doses of very simple shape, for example parallelepiped. These doses do not require coextruder devices having complicated conduits and even more complicated obturator systems. This enables the compression-moulding apparatus to be simplified. In a twelfth aspect of the invention, a method is provided which comprises a stage of compression-moulding a multilayer dose in a forming chamber, the dose comprising a principal material and a secondary material, characterised in that during the moulding the principal material flows into the forming chamber more rapidly than the secondary material, such as to surround the secondary material in order to obtain an object in which the secondary material is embedded in the principal material.

Thanks to the twelfth aspect of the invention, it is possible to obtain a compression-moulded object in which the secondary material does not exit onto the external surface of the object. The principal material rapidly fills the forming chamber and, in the moulded object, the secondary material is confined to the inside of a layer of principal material, even though, in the dose, the secondary material was exposed on the external surface. It is therefore possible to prevent the drawbacks from emerging when the secondary material emerges on the external surface of the moulded object, without dispensing the secondary material intermittently.

In a thirteenth aspect of the invention, a compression-moulded object is provided, comprising a body formed from a first material and a second material, characterised in that the second material is a composite material.

In a version, the compression-moulded object is a preform. Alternatively, the compression-moulded object can be a cap or a container.

In a version, the second material is a nano-composite material. In a further version, the second material is a material obtained using the Layer

Multiplier System technology.

The composite material included in the second material of the object of the thirteenth aspect of the invention guarantees a good margin of liberty in choosing the properties of the object, In a fourteenth aspect of the invention, a preform is provided having a body formed entirely from a material obtained using the Layer Multiplier System technology.

Thanks to this aspect of the invention, a preform can be obtained, and consequently a container, having good barrier properties, without using co- extrusion systems for obtaining the dose. The material obtained by the Layer

Multiplier System technology comprises a matrix material in which a plurality of layers are sunk, which layers are realised in a different material from the matrix material and which are able to give the preform good barrier properties. In a fifteenth aspect of the invention, a method is provided which comprises compression-forming a multilayer dose of plastic material for obtaining a part of a container which is provided with a container-neck element.

Since the multilayer dose can comprise at least a layer made with a material having gas and/or light barrier properties, a part of a container having the above-cited properties can be obtained.

In a version, a multilayer structure of plastic material is dispensed in an outlet direction by means of a plasticiser device, the multilayer dose being severed firom the multilayer structure of plastic material and the multilayer dose supplying mould means for compression-forming provided with first forming means and second forming means, the compression-forming comprising reciprocally moving the first forming means and the second forming means in a moulding direction which is transversally arranged with respect to the outlet direction.

In this way, a layer of barrier material can be obtained which occupies the whole extension of the part of container.

The multilayer structure of plastic material - and therefore the multilayer dose obtained therefrom - can be conformed as a laminar or sheet element.

The above-mentioned laminar or sheet element defines a plane which is transversally arranged - in particular substantially perpendicular — with respect to the moulding direction.

In a version, the compression forming comprises realising a container neck element provided with a thread.

In a sixteenth aspect of the invention, a method is provided which comprises stages of: dispensing, by means of a coextruder device, a structure comprising at least a principal material and a secondary material arranged in a predetermined number of layers; introducing a dose severed from the structure into a cap, the dose having a number of layers that is equal to the number of layers of the structure exiting from the coextruder device; obtaining a disc element which adheres to an end wall of the cap, by compression-moulding the dose internally of the cap.

In a seventeenth aspect of the invention, a cap is provided which comprises an end wall, a lateral wall which projects from the end wall and a disc element adhering to the end wall, the disc element having at least an internal layer which is interposed between two external layers, characterised in that the external layers have the same composition.

Thanks to the sixteenth aspect of the invention, a cap can be obtained which includes a multilayer disc element, in which the disc element can be manufactured with a reduced consumption of material. Since the disc element is obtained by compression-moulding of a multilayer dose internally of the cap, unused cuttings are not generated. Further, the compression moulding enables forming of disc elements having a very small thickness, which further reduces the consumption of material.

The method of the sixteenth aspect of the invention enables a cap to be obtained according to the seventeenth aspect of the invention, in which the external layers of the disc element have the same composition because both are formed from the principal material of the dose. In this cap, the internal layer, which can comprise a barrier material, is interposed between the internal layers. When the cap is used to close a container containing a substance, the external layers of the disc element prevent direct contact between the above-mentioned substance and the internal layer. This prevents the material of the internal layer from contaminating the substance contained in the container.

The invention will be better understood and actuated with reference to the accompanying drawings, which illustrate some non-limiting examples of embodiments of the actuation, in which: figure 1 is a schematic view, partially sectioned, of an apparatus for compression-moulding a multilayer object; figure 2 is a schematic plan view of a multilayer dose which is processable by the apparatus of figure 1; figure 3 is a view as in figure 2, evidencing a multilayer dose in an alternative versions; figure 4 is a view as in figure 2, evidencing a multilayer dose in a further alternative version; figure 5 is a schematic section evidencing some stages of a process for obtaining a multilayer object; figure 6 is a section of a cap for containers having a multilayer end wall; figure 7 is a current section showing a detail of the cap of figure 6; figure 8 is an enlarged section as in figure 7, showing a detail of a cap in an alternative version; figure 9 is a schematic plan view of a machine for forming by compression of plastic material; figure 10 is a transversal section of a dose of plastic material, which can be formed by compression in the machine of figure 9; figure 11 is a schematic transversal section showing a container neck; figure 12 is a plant view of the container neck of figure 11; figure 13 is a view as in figure I₅ showing an apparatus for compression moulding multilayer preforms; figure 14 is a longitudinal section of a preform obtained using the apparatus of figure 13; figure 15 is a longitudinal section of a preform obtained using the apparatus of figure 14; figure 16 is the view of figure 15, evidencing a multilayer dose according to an alternative version; figure 17 is a schematic plan view of an apparatus for extruding a multilayer structure of a plastic material; figure 18 is a schematic lateral view of a coextruder device for extruding a multilayer dose having a tubular secondary material; figure 19 is a schematic lateral view, partially sectioned, of a moulding die for compression-moulding of the dose extruded from the coextruder device of figure 18; figure 20 is a schematic longitudinal section of a dose extruded from the coextruder device of figure 18; figure 21 is a longitudinal section as in figure 20, showing a dose in an alternative version; figure 22 is a longitudinal section as in figure 20, showing a dose in a further alternative version; figure 23 is a schematic longitudinal section of a preform obtained by compression-moulding of the dose of figure 20; figure 24 is longitudinal section of a mould in which a compression-moulding is made of the dose of figure 20, the dose being correctly positioned internally of a cavity of the mould; figure 25 is a longitudinal section as in figure 24, in which the dose is not correctly positioned internally of the mould cavity; figure 26 is a schematic section, showing a die in which a multilayer dose is positioned, which is destined to be transformed into a cap; figure 27 is an enlarged view of the multilayer dose processed by the mould of figure 26; figure 28 is a schematic transversal section of a cap obtained by the dose of figure 27; figure 29 is an enlarged transversal section of a portion of the mould of figure 26, during a filling stage; figure 30 is a schematic transversal semisection, showing a coextrusion head for extruding a multilayer structure from which the doses of figures from 20 to 22 or 27 can be obtained; figure 31 is a semi-section such as that of figure 30, showing a coextrusion head from which the doses of figure 21 or 22 can be obtained, in a partially- closed position; figure 32 is a schematic semi-section showing a coextrusion head for extruding a multilayer structure having a plurality of concave portions, in an open position; figure 33 is a schematic section as in figure 32, showing the coextrusion head in a partially-closed position; figures from 34 to 38 show a semi-section of the plastic material flowing in an extrusion conduit arranged downstream of the coextrusion head of figure

32, in fives successive stages of the coextrusion process; figures 39 and 40 show two embodiments of the extrusion conduits of figures from 34 to 38; figure 41 is a schematic section of a multilayer dose obtainable by means of an extrusion conduit of the type shown in figures from 34 to 38; figure 42 is a section as in figure 41, showing a multilayer dose in a further embodiment; figure 43 is a section as in figure 41, showing a multilayer dose in a further embodiment; figure 44 is a schematic section of a multilayer structure from which doses can be severed, which doses have a first quantity and a second quantity of secondary material; figure 45 is a schematic section of a mould for compression-moulding of a dose severed from the multilayer structure of figure 44; figure 46 is a schematic section of a preform obtained in the mould of figure

45; figures from 47 to 52 show some possible conformations of multilayer doses; figures 53 and 54 show two alternative versions of a multilayer dose comprising a secondary material which includes a composite material; figures from 55 to 57 show a schematic section of a mould in which a plurality of doses for obtaining a multilayer object is positioned; figure 58 is a schematic section of a cap for a container; figure 59 is an enlarged schematic section of a multilayer dose for obtaining a disc element in the cap of figure 58; figure 60 is a schematic section showing the dose of figure 59 deposited internally of the cap of figure 58; figure 61 is a view from above of the cap and the dose of figure 60; figure 62 is a section as in figure 60, showing a punch in contact with the dose; figure 63 is a section as in figure 62, in a stage in which the punch begins to shape the dose; figure 64 is a view from above of the cap and the dose of figure 63; figure 65 is a section as in figure 63, in a stage in which the punch has further deformed the dose; figure 66 is a view from above of the cap and the dose of figure 65; figure 67 is a schematic section of a cap comprising a disc element; figure 68 is a section as in figure 59, showing a multilayer dose in a further version thereof; figure 69 is a schematic section as in figure 60, showing the dose of figure 59 deposited internally of a cap according to a further version; figure 70 is a section as in figure 69, showing a punch in contact with the dose; figure 71 is a section as in figure 70, in a stage in which the punch has started to deform the dose; figure 72 is a section as in figure 71, in a stage in which the punch has further deformed the dose; figure 73 is a schematic section of the cap of figures from 69 to 72, internally of which a disc element has been formed.

Figure 1 shows an apparatus 1 for compression moulding doses of plastic material such as to obtain multilayer objects.

The apparatus 1 comprises a coextruder device 3 for dispensing a multilayer structure 2 of plastic material. The coextruder device 3 can actuate a coextrusion process such as to contemporaneously coextrude at least two different plastic materials. For example, the coextruder device 3 can enable a principal material 4 to be extruded, internally of which a secondary material 5 is arranged. The principal material 4 can comprise a plastic base material which can provide the finished object with the desired mechanical and aesthetic properties, for example a thermoplastic polymer such as polyethylenetherephthalate (PET), polypropylene (PP), polyvinylchloride (PVC), polyethylene (PE), polyethylene naphthalate (PEN), polystyrene (PS) or lactic polyacid (PLA). The secondary material 5 can comprise a barrier plastic material provided with barrier properties against oxygen, and/or smells, and/or moisture, and/or light. The barrier plastic material can for example comprise an aromatic polyamide NMXD6. Alternatively, the secondary material 5 can comprise any recycled plastic material, or a material of the same type as the principal material 4 with addition of one or more colorant substances for giving light barrier properties, for example black, or a material of the same type as the principal material 4 with an addition of an oxygen-scavenging substance. The coextruder device 3 is provided with a coextrusion head comprising a main conduit 6 from which the principal material 4 exits. A secondary conduit 7, from which the secondary material 5 exits, is arranged at least partially internally of main conduit 6. In the illustrated example, the main conduit 6 has an outlet transversal section shaped as a rectangle having a larger base which is substantially horizontally. Similarly the secondary conduit 7 comprises a transversal outlet section having a rectangular shape, a larger side of which is substantially horizontal. The multilayer structure 2 is thus in the shape of a sheet. The main conduit 6 and the secondary conduit 7 can also have outlet sections in a non-rectangular shape, for example triangular, square, circular or in general polygonal.

The multilayer structure 2 exits from the coextruder head in an outlet direction X, which in the example of figure 1 is substantially horizontal. Multilayer doses 8 are successively severed from the multilayer structure 2, one of which multilayer doses 8 is shown in figure 2, for example via a cutting device, not illustrated as of known type. The cutting device can comprise a cutter rotating about a rotation axis, or a plurality of cutting elements mobile along a looped path. Each multilayer dose 8 is compression-moulded in a mould 9 comprising first forming means and second forming means. The first forming mans can for example comprise a female mould element 10 having a forming cavity 11 in which the multilayer dose 8 is received. The second forming means can comprise a male moulding element 12 which is destined to be received in the forming cavity 11 for shaping the multilayer dose 8. The multilayer dose 8, after having been severed from the multilayer structure 2, can be transported towards the mould 9 by a transferring device of known type.

In a version, the apparatus 1 can comprise a plurality of moulds 9 mounted on a forming carousel, rotatable about a rotation axis, for example vertical. In this case, the transferring device can comprise a plurality of transferring elements that are mobile along a looped path. Each transferring element is destined to receive a multilayer dose 8 and to transport it towards a corresponding mould 9. The female mould element 10 and the male mould element 12 are mobile with respect to one another in a moulding direction Y, between an open position, shown in figure 1, in which the multilayer dose 8 is received in the forming cavity 11, and a closed position, not illustrated, in which the desired object is obtained from the multilayer dose 8. For example, the female moulding element 10 can be mobile while the male moulding element 12 is fixed or, on the contrary, the male moulding element 12 can move to near and distance from the female moulding element 10, which stays still. Also possible is that the female moulding element 10 and the male moulding element 12 both move, nearing to one another or distancing from one another according to need.

The female moulding element 10 and the male moulding element 12 are moved by movement means which can be associated to the female moulding element 10, the male moulding element 12 or both the elements. The movement means can comprise for example an actuator or a cam system. The moulding direction Y is transversal with respect to the outlet direction X. For example, the moulding direction Y can be perpendicular to the outlet direction X. In the illustrated example, the moulding direction Y is substantially vertical while the outlet direction X is substantially horizontal. In the illustrated example, each multilayer dose 8 has a parallelepiped shape having a height which is much smaller than a length of the sides which define the base.

Both the principal material 4 and the secondary material 5 respectively define prismatic elements, in particular parallelepiped, having respective dimensions measured along the moulding direction Y, which are less than the dimensions thereof measured transversally to the moulding direction Y. In other words, in the multilayer dose 8 the principal material 4 and the secondary material 5 each have vertical dimensions which are smaller than the horizontal dimensions.

The secondary material 5 extends mainly on a plane, which in the example is figure 1 is horizontally arranged. When the female moulding element 10 and the male moulding element 12 near one another, the multilayer dose 8 is shaped such as to form the desired object. In the example illustrated in figure 1, the moulded object is a cap 13 having an end wall 14 which is substantially flat and a lateral wall 15 which is substantially cylindrical. The lateral wall 15 is internally provided with fixing means, not illustrated, which engage removable with corresponding fixing means provided on a container neck that the cap 13 is destined to close. In the multilayer dose 8, the second material 5 forms a flat layer which mainly extends on a transversal plane, and more particularly perpendicular with respect to the moulding direction Y. The secondary material 5 is crushed between the female moulding element 10 and the male moulding element 12 and is distributed uniformly internally of the end wall 14, which is also transversal, and in particular perpendicular to the moulding direction Y. Further when the multilayer dose 8 rises between the female moulding element 10 and the male moulding element 12, the secondary material 5 can be distributed internally of the lateral wall 15 such as to give the lateral wall 15 barrier properties too. In the version illustrated in figure 1, the secondary material 5 does not fold on itself internally of the principal material 4. In other words, the secondary material 5 forms a single layer internal of the principal material 4. In the example of figure 1, the multilayer dose 8 is of the type shown in figure 2, i.e. the secondary material 5 forms a layer which is completely sunken in the principal material 4. In other words, the secondary material 5 is does not face any external surface of the multilayer dose 8. This conformation is obtained by continuously extruding the principal material 4 from the main conduit 6, while the secondary material 5 is extruded intermittently through the secondary conduit 7. Two adjacent multilayer doses 8 are then severed by cutting the multilayer structure 2 in a region in which the secondary material 5 is absent.

In this case the secondary material 5 does not appear on the external surface of the formed object, but remains completely sunken in the principal material 4. This means that, as illustrated in figure 1, the lateral wall 15 of the cap 13 is delimited by a free edge 16 on which the principal material 4 does not surface.

If both the principal material 4 and the secondary material 5 are extruded continuously, but the secondary conduit 7 of the coextruder device 3 is narrower than the main conduit 6, a multilayer dose 18 of the type shown in figure 3 is obtained. In this case, the secondary material 5 forms a flat layer having two surfaces 17 arranged transversally with respect to the outlet direction X which face externally of the multilayer dose 18. The layer of secondary material 5 also has two further surfaces 21, arranged parallel to the outlet direction X, which do not surface externally of the multilayer dose 18 as they are sunken in the principal material 4.

It is further possible to extrude both the principal material 4 and the secondary material 5 continuously, respectively through a main conduit 6 and a secondary conduit 7 having about the same length. In this case, a multilayer dose 28 is obtained of the type shown in figure 4, in which the secondary material 5 forms an intermediate layer interposed between two external layers of principal material 4, the intermediate layer and the external layer having, in plan view, the same size. This means that the multilayer dose 28 has four lateral walls 26 on each of which the secondary material 5 surfaces. The multilayer doses 18 and 28 illustrated respectively in figures 3 and 4 can be obtained more simply with respect to the multilayer dose 8 illustrated in figure 2. However, in some applications, the multilayer doses 18 and 28 do not lead to significant differences in the final object with respect to the multilayer dose 8.

The apparatus 1 illustrated in figure 1 can also be used for forming different objects from the caps 13, for example seals which are possibly moulded internally of caps formed previously, or containers provided with a small axial dimension.

Figure 6 shows a cap 223 which differs from the cap 13 shown in figure 1 mainly because it comprises a seal lip 224 which projects from the end wall 14 towards the inside of the lateral wall 15. The seal lip 224 has a substantially annular shape and is destined to engage with a neck of a container, for example a bottle, in order to sealingly close the container. The cap 223 further comprises an anti-intrusion security ring 217, connected to the wall 15 by means of a plurality of bridge elements 222, destined to be broken the first time the cap 223 is removed from the corresponding container.

The end wall 14 has a multilayer conformation, being formed by at least an interlayer 227 of secondary material 5 interposed between two external layers of principal material 4.

The interlayer 227 is extended also internally of the seal lip 224. In this way, if the secondary material 5 is a barrier material, the capacity of the seal lip 224 to close and seal the container is much improved. Further, the secondary material 5 can also extend internally of the lateral wall 15.

In a version, shown in figure 7, the secondary material 5 forms a single interlayer 227. Internally of the seal lip 224, the interlayer 227 forms a substantially V-shaped fold 225. The fold 225 derives from reasons connected to the viscosity of the materials used and the mould-filling techniques used, in particular the speed of the filling.

The interlayer 227 originates internally of the seal lip 224, two layers of secondary material 5, which enables an improvement of the properties of the seal lip 224, particularly the barrier properties. The cap 223 shown in figures 6 and 7 can be obtained with a process the main stages of which are illustrated in figure 5, in a way which is substantially similar to what has already been described with reference to figure 1. In this case, a multilayer dose 258 can be used having a single layer 226 of secondary material 5, at least partially sunken into the principal material 4. In an alternative version, shown in figure 8, internally of the end wall 14 there can be two interlayers 207 of secondary material 5, sunken into the principal material 4. Both the interlayers 207 are folded in the seal lip 224, for example one internally of the other, such that, at least in a part of the seal lip, there are four layers of secondary material 5 present.

This enables an improvement in the properties of the seal lip 224, given by the secondary material 5, particularly the barrier properties. The cap shown in figure 8 can be obtained with a similar process to that of figure 5, using a multilayer dose having two layers of secondary material 5. With reference to figure 9, a machine 400 is shown for forming a plasticiser device 401, for example a coextruder device, arranged to provide a multilayer structure of plastic material in the paste state, for example a multilayer extrudate 409 of plastic material in the paste state, and cutting means, not illustrated, arranged to cut the multilayer extrudate 409 in order to obtain doses 402 of plastic material.

As shown in figure 10, the doses 402 comprise a plurality of superposed layers. The doses 402 can comprise a first external layer 403 and a second external layer 404 formed from a first plastic material and an internal layer 405, interposed between the first external layer 403 and the second external layer 404, formed from a second plastic material. In particular, the second plastic material can have barrier properties to gas and/or light, while the first plastic material does not have these properties.

In a version, the first plastic material can be polypropylene (PP) and the second plastic material can be polyvinyl alcohol (PVOH). The first plastic material can also be any one of the plastic materials previously listed for the principal material 4, while the second plastic material can be any one of the plastic materials previously listed for the secondary material 5. The doses can comprise a number of layers which is greater than three, and in particular more than one layer formed by a material having barrier properties to gas and/or light.

The machine 400 further comprises a compression moulding device 406. The compression moulding device 406 comprises a rotatable carousel 407 which supports a plurality of compression-forming moulds 408 provided with a first half-mould, for example a male half-mould, and a second half-mould, for example a female half-mould, which are mobile in reciprocal nearing and distancing thanks to special movement means. The machine 1 further comprises a transfer device, not shown, which collects the doses from the plasticiser device 401 and inserts them in the compression- forming moulds 408.

The compression-forming moulds 408 shape the doses 402 in order to obtain dome-shaped segments 411 of the type shown in figures 11 and 12. The dome-shaped segments 411 comprise a container neck element 410 for dispensing a substance contained internally of the container. The segments 411 comprise a connecting zone 413 which will be fixed, for example by welding, to a body of a container, not illustrated, for example a bottle made of aplastic material. The container neck element 410 is provided with means for fixing for engaging removably with a cap, not illustrated. The fixing means can comprise, for example, a threaded portion 412.

Thanks to the machine 400, in a single compression-forming operation the segment 411 can be obtained provided with the container neck element 410 on which the fixing means 412 are fashioned.

In particular, a segment 411 can be obtained which is provided with a barrier layer against gas and/or light. The machine 400 functions similarly to the apparatus shown in figures 1 and

5.

During functioning, the plasticiser device 401 dispenses the multilayer extrudate 409 in an outlet direction. The first half-mould and the second half-mould move reciprocally nearingly, in order to compression-form a dose 402 severed from the mulilayer extrudate

409, along a moulding direction which is transversally arranged with respect to the outlet direction. In particular, the moulding direction is perpendicular to the outlet direction, For example, the outlet direction can be substantially horizontal, while the moulding direction is substantially vertical.

The multilayer extrudate 409 - and the dose 402 obtained therefrom - can be conformed as a laminar- or sheet-element.

In this case, the transfer device delivers the dose 402 to a corresponding compression-forming mould 408 such that the dose 402 identifies a plane arranged transversally, in particular perpendicularly, to the above-mentioned moulding direction.

Figure 13 illustrates and apparatus 31 in an alternative version which is suitable for forming elongate objects, for example preforms 43 of the type shown in figure 14. The preforms 43 typically have a tubular body 45 extending about a longitudinal axis Z. The tubular body 45 is closed at a first end thereof by an end wall 44. A mouth 47 is fashioned at a second end of the tubular body 45, which mouth 47 includes fixing means comprising, for example, a thread 49 which can engage with a cap of a container. The apparatus 31 comprises a coextruder device 33 having a main conduit 36 and a secondary conduit 37 from which exit, respectively, in the outlet direction X₅ the principal material 4 and the secondary material 5. Thus a multilayer structure 32 is obtained from which, via a cutting device, not illustrated, multilayer doses 38 of the type illustrated in figure 16 are severed. The cutting device can comprise a blade which is rotatable about a rotation axis such as to interact periodically with the multilayer structure 32. The multilayer doses 38 are have an elongate parallelepiped shape, which can have a larger side or height extending in a direction corresponding to the longitudinal axis Z of the preform 43. The larger side, or height, is transversal with respect to the outlet direction X. The secondary material 5 present in the multilayer dose 38 is also parallelepiped with a larger side extending in a direction that corresponds to the longitudinal axis Z of the preform 43. The secondary material 5 is arranged in a lower portion, for example in the lower half, of the multilayer dose 38. In the example of figure 16, the secondary material 5 is totally sunken into the principal material 4, i.e. there are not portions of secondary material 5 emerging onto the external surface of the multilayer dose 38. In order to obtain a multilayer dose 38 of this type, a coextruder device 33 is used which has a secondary conduit 7 having an outlet section which is narrower than the outlet section of the main conduit 6. Further, the secondary material 5 is extruded intermittently while the principal material 4 is extruded continuously. Two adjacent multilayer doses 38 are thus severed by cutting the multilayer structure 32 in a region in which the second material 5 is absent.

The multilayer dose 38 is thus inserted internally of a mould 39 in which the preform 43 will be formed. The apparatus 31 can comprise a plurality of moulds 39, for example arranged in a peripheral region of a rotating moulding carousel. Further, a transferring device can be provided, for example comprising a plurality of transferring elements, mobile along a looped path, each of which collects a multilayer dose severed by the cutting device and delivers the dose to a relative mould 39. The transferring elements enable the doses to be correctly inserted in the corresponding moulds 39, preventing the doses from being positioned wrongly, which would make it impossible to obtain preforms 43 of good quality.

The die 39 comprises a female moulding element 40 having a forming cavity 41 in which the multilayer dose 38 is received. The female moulding element 40 enables external shaping of the tubular body 45 and the end wall 44 of the preform 43. A male moulding element 42 cooperates with the female moulding element 40 in order to internally shape the preform 43. The female moulding element 40 and the male moulding element 42 are mobile with respect to one another, thanks to movement means moving in a transversal moulding direction Y, for example perpendicular with respect to the outlet direction X. The moulding direction Y can be for example vertical, while the outlet direction X can be horizontal, as illustrated in figure 13. When the female moulding element 40 and the male moulding element 42 near one another, the multilayer dose 38 is shaped such as to obtain the preform 43. The mould 39 further comprises at least a pair of mobile elements 50 for fashioning the thread 49. The mobile elements 50 can move trans versally to the moulding direction Y in order to disengage from the thread 49 after the thread 49 has been formed, thus enabling the preform 43 to be extracted from the mould 39.

When the male moulding element 42 penetrates internally of the forming cavity 11, the multilayer dose 38 is crushed between the female moulding element 40 and the male moulding element 42 and gradually forms the preform 43. The secondary material 5 distributes uniformly along the tubular body 45 and in the end wall 44, giving rise to a thin intermediate layer having, for example, barrier properties. This intermediate layer is interposed between an external layer and an internal layer of principal material 4, as shown in figure 14.

The secondary material 5 does not fold in on itself during the compression- moulding of the preform 43. Consequently, the number of layers of secondary material 5 present in the preform 43 is the same as the number of layers of the secondary material 5 which were present in the multilayer structure 32 and in the multilayer dose 38.

Since in the multilayer dose 38 the secondary material 5 is totally sunken into the principal material 4, in the preform 43 too there are no portions of secondary material 5 emerging onto the external surface.

Further, since the secondary material 5 is arranged in the lower region of the multilayer dose 38, when the multilayer dose 38 is shaped to form the preform 43 the secondary material 5 cannot reach the mouth 47. Consequently, the secondary material 5 is not present at the thread 49. This means that the mechanical properties of the thread 49 are not compromised; the mechanical properties might instead be diminished by certain types of secondary material.

In an alternative version, the apparatus 31 can enable multilayer doses 48 of the type shown in figure 15 to be obtained, having at least two external surfaces 34 on which the secondary material 5 is present. The multilayer dose

48 is obtained by means of a coextruder device 33 in which both the principal material 4 and the secondary material 5 are extruded continuously.

The apparatus 31 shown in figure 13 can also be used for compression moulding objects which are different from the preforms 43, for example containers having a relevant axial dimension. Note that by compression-moulding doses of multilayer plastic material in a moulding direction Y which is transversal with respect to the outlet direction X, it is possible to obtain objects having even complicated shapes, such as the preforms 43, by using particularly simple multilayer doses, in which the secondary material 5 has a substantially flat or at most prismatic shape. Thus the need to use multilayer doses in which the secondary material has a particularly complicated geometry can be avoided.

Further, it is not necessary to rotate the dose at outlet from the coextruder device in order to position the dose correctly with respect to the moulding direction.

In a version, to which reference is made in figure 17, the apparatus can comprise a coextruder device 53 for extruding the multilayer structure 2 downstream of which there is a modelling device 51 for modelling the multilayer structure 2 according to a desired geometry. In particular, the moulding device 51 enables the multilayer structure 2 to be stretched and the molecules making it up to be orientated in one or two desired directions. The modelling device 51 can comprise a plurality of roller couples 52. In the illustrated example, the roller of each pair of rollers 52 have respective transversal axes, for example perpendicular, to the outlet direction X. The rollers of each pair of rollers 52 rotate about the respective axes with rotation velocities which grow progressively on distancing from the coextruder device 53, such as to thin out the multilayer structure 2. At the same time, the width of the multilayer structure 2 transversally of the outlet direction X increases. This enables the dimensions of the multilayer structure 2 to be modified such as to obtain multilayer doses of the desired measurements, according to the object to be moulded. Further, by orientating and stretching the molecules of the multilayer dose, the properties of the principal material 4 and the second material 5 can be improved.

In a version which is not illustrated, the rollers of the pairs of rollers 52 can have longitudinal axes which are not perpendicular to the outlet direction X, for example parallel or oblique to the outlet direction X. Further, the modelling device 51 can be positioned downstream of the cutting device, such as to interact with the plastic material after the multilayer doses have been severed from the multilayer structure 2. The process described up to this point enables multilayer objects to be obtained which can also comprise more than one different material. As well as the principal material 4 and the secondary material 5, it is possible to use a third material, for example a connecting material which can make the principal material 4 and the second material 5 compatible to one another. In this case the coextruder device comprises a third extrusion conduit for extruding the connecting material. Thus objects are obtained which comprise an intermediate layer of secondary material 5, interposed between two layers of connecting material in turn interposed between two external layers of principal material 4. It is possible to produce multilayer doses which are composed of an arbitrary number of materials, dispensed via corresponding extrusion conduits.

Further, all the multilayer doses described up to this point can comprise more than one layer of secondary material 5, each layer of secondary material being interposed between two layers of principal material 4. Finally, the principal conduit 6 and the secondary conduit 7 can have respective outlet sections of different shapes from the rectangular shape, such as to extrude multilayer doses having a shape which is not necessarily parallelepiped.

Figure 18 shows the terminal part of a coextruder device 63 for extruding a multilayer structure 63 comprising a principal material 64 and a secondary material 65. The principal material 64 and the secondary material 65 can be constituted by the same plastic materials previously listed with reference to the principal material 4 and the secondary material 5. The coextruder device 63 can have an outlet section that is substantially circular, such that the multilayer structure 62 has a cylindrical shape. In an alternative version, the outlet section of the coextruder device 63 can be non-circular, for example triangular, square, rectangular or, more generally, polygonal. In this case, the multilayer structure 62 will have a corresponding prismatic shape. The secondary material 65 has a tubular shape, for example a hollow cylinder shape or a hollow prism.

The multilayer structure 62 exits the coextruder device 63 along an outlet direction X. Thereafter, multilayer doses of the type shown in figure 20 are severed by a cutting device of known type. Each multilayer dose 68 comprises a body 66 extending along a longitudinal axis H. The body 66 is formed from the principal material 64, internally of which the secondary material 65 forming a tubular layer 61 is at least partially contained. The tubular layer 61 extends about the longitudinal axis H and is surrounded, both internally and externally, by the principal material 64. In the illustrated example, the tubular layer 61 has the shape of a hollow cylinder, but the layer could also have a hollow prismatic conformation. The tubular layer 61 has a first annular end 69 which is opposite a second annular end 70. The first annular end 69 is arranged on a first end surface 71 of the multilayer dose 68, the first end surface 71 being opposite a second end surface 72 on which the second annular end 70 is arranged. The first end surface 71 and the second end surface 72 delimit the body 66 transversally to the longitudinal axis H and, in the illustrated example, they are substantially perpendicular to the longitudinal axis H.

The body 66 is further delimited by an external lateral surface 74, arranged about the longitudinal axis H.

The multilayer dose 68 is suitable for compression-moulding such as to obtain an elongate object, for example a preform 73 schematically shown in figure 23. The preform 73 can be transformed into a container by blowing or stretch-blowing.

To obtain the preform 73, the multilayer dose 68 is inserted in a mould 79, shown in figure 19, entirely similar to the mould 39 shown in figure 13. The parts of the mould 79 which are the same as those of the mould 39 are denoted using the same reference numbers used in figure 13 and will not be newly described in detail. In this case too, a plurality of moulds 79 can be provided, all the same and mounted along a peripheral region of a carousel which is rotatable about a rotation axis which can be substantially vertical. A transferring device, not illustrated, can enable the multilayer doses 68 to be conveyed from the coextruder device 63 towards the moulds 79. The transferring device ensures that the multilayer doses 68 are positioned correctly internally of the respective forming cavities 41 of the moulds 79, as shown in figure 24. In particular, each multilayer dose 68 is positioned substantially at the centre of the corresponding forming cavity 41, the longitudinal axis H of the multilayer dose 68 being substantially parallel and indeed coincident with the longitudinal axis of the forming cavity 41. In this way high-quality preforms 73 can be obtained. If the multilayer dose 68 were introduced into the forming cavity 41 in a decentred position, or with the longitudinal axis H significantly displaced with respect to the longitudinal axis of the forming cavity 41. a situation of the type shown in figure 25 would be generated, which would surely lead to obtaining a defective preform, or indeed to not obtaining any preform, should the badly-positioned multilayer dose 68 prevent the closure of the mould 79. After the multilayer dose 68 has been inserted in the forming cavity 41, the mould 79 is closed by moving the female moulding element 40 and the male moulding element 42 with respect to one another in a moulding direction Y, see figure 19. The moulding direction Y can be substantially parallel to the outlet direction X and to the longitudinal axis H of the multilayer dose 68. The principal material 64 progressively fills the space identified between the female mould element 40 and the male moulding element 42, thus forming a lateral wall 55 of the preform 73, shown in figure 23 and having a tubular shape, and an end wall 54 which closes the lateral wall 55. A mouth 56 is afforded at an end of the lateral wall 55 opposite the end wall 54, which mouth 56 is destined to engage with a cap in the finished container. The mouth 56 is provided with fixing means, not illustrated, for example a thread, for enabling the cap to be removable fixed to the container. When the multilayer dose 68 is compression-moulded, the secondary material 65 forms an intermediate layer 57 which is completely sunken into the principal material 64. The intermediate layer 57 is arranged along the lateral wall 55, about a longitudinal axis Z of the preform 73. The intermediate layer 57 does not extend into the mouth 56, nor into the end wall 54. In other words, the intermediate layer 57 does not extend over the whole length Ll of the preform 73, but only over a part of the length Ll. For example, the intermediate layer 57 can extend only along eighty per cent, or even less, of the length Ll.

This conformation of the intermediate layer 57, which extends only over a part of the length Ll, for example only over eighty per cent of the length, can be encountered not only in the preform 73 shown in figure 23, but also in all the preforms to which reference is made in this description. Also possible is that the intermediate layer 57 does not extend over all the end wall 54, but that the end wall exhibits a central region in which the intermediate layer 57 is not present. The intermediate layer 57 of the preform 73 has a tubular shape which is geometrically similar to that of the tubular layer 67 of the multilayer dose 68, even if it has different dimensions. In other words, in the passage from the multilayer dose 68 to the preform 73 the secondary material 65 does not undergo excessive changes of shape. This has been made possible by the special conformation of the multilayer dose 68, in which the tubular layer 67 is very close to the external lateral surface 74. In particular, the distance D between the tubular layer 67 and the external lateral surface 74, shown in figure 20, is equal to or less than the length S of the lateral wall 55 of the preform 73, shown in figure 23. Note that figures 20 and 23 are schematic and do not reproduce the real dimensions of the multilayer dose 68 and the preform 73.

The distance D can be less than 4 mm, for example less than 2.5 mm. In a version, the distance D can be less than 2 mm. Thanks to the small distance D, the secondary material 65 is not subject to folding nor breaking during the compression moulding, and fills the space identified between the female moulding element 40 and the male moulding element 42, following uniform filling flows. This enables a preform 73 to be obtained, and successively a container, in which the properties given by the secondary material 65, for example the barrier properties, are uniform along the whole lateral wall.

Note that the secondary material 65 does not emerge either onto the external surface or onto the internal surface of the preform 73. A similar situation exists in the container obtained from the preform 73. This is positive from both the technical point of view and from the hygienic point of view, as the secondary material 65 does not come into contact with the external environment, nor with the substance contained in the container. Figure 21 shows a multilayer dose 78 in an alternative version. The multilayer dose 78 differs from the multilayer dose 68 shown in figure 20 because the tubular layer 67 comprises a first annular end 59 which is contained within the principal material 64, i.e. it does not emerge onto the first end surface 71 of the body 66. A second annular end 60 of the tubular layer 67 is arranged on the second end surface 72 of the body 66.

Figure 22 shows a multilayer dose 88 of a further alternative version, which differs from the multilayer dose 68 illustrated in figure 20 because the tubular layer 67 comprises a first annular end 89 and a second annular end 90, both sunken into the principal material 64. In other words, neither the first annular end 89 nor the second annular end are arranged on the corresponding end surfaces 71 and 72.

The multilayer doses 78 and 88 illustrated in figures 21 and 22 are obtained by extruding the principal material 64 continuously, while the secondary material 6 is extruded intermittently. The multilayer doses 78 and 88 are thus more difficult to obtain with respect to the multilayer dose 68 shown in figure 20, but they can be useful in some particular cases. Figure 27 illustrates a multilayer dose 98, destined to be compression- moulding to form an object having a longitudinal dimension and a transversal dimension having a low reciprocal ratio, being for example a cap for a container. The multilayer dose 98 comprises a body 96 extending along a longitudinal axis H, formed by a principal material 94 in which a secondary material 95 is at least partially sunk. The principal material 94 and the secondary material 95 can be formed from the same plastic materials which form the principal material 4 and the secondary material 5 of the multilayer dose 8 shown in figure 2.

The body 96 can be cylindrical or prismatic. The body comprises at least a layer 97 of secondary material 95. The layer 97 can be tubular, for example cylindrical or a hollow prism, surrounded both internally and externally by the principal material 94. The multilayer dose 98 can also be parallelepiped and the secondary material 95 can form two distinct flat layers arranged on opposite sides of the longitudinal axis H, for example in a symmetrical position with respect to the longitudinal axis H.

The layer 97 is at a distance dl from the longitudinal axis H. The body 96 is delimited by an external lateral surface 84, which can extend about the longitudinal axis H. The distance between the longitudinal axis H and the external lateral surface 84 is denoted by d2. For example, in a case in which the body 96 has a cylindrical shape and the layer 97 defines a tubular sleeve, also cylindrical, the distance dl is the radius of the tubular sleeve, while the distance d2 is the external radius of the multilayer dose 98. The distance dl between the layer 97 and the longitudinal axis H is comprised between 10% and 50% of the distance d2 between the external lateral surface 84 and the longitudinal axis H. In other words, the following ration obtains: 10% d2 ≤ dl < 50% d2

This means that the layer 97 is relatively close to the longitudinal axis H, for reasons which will be explained herein below.

The multilayer dose 98 is inserted into a forming cavity 101 of a mould 99, illustrated in figure 26, the mould 99 comprising a female moulding element 100 in which the forming cavity 101 is afforded and a male moulding element 102.

The female moulding element 100 and the male moulding element 102 are mobile to one another along a moulding direction Y, thanks to special movement means. In this way, the female moulding element 100 and the male moulding element 102 can reciprocally near in order to compression-mould the multilayer dose 98 and obtain a cap 23, shown in figure 28. Successively the female moulding element 100 and the male moulding element 102 are distanced from one another in order to enable the cap 23 to be extracted from the mould 99. The moulding direction Y is transversal, for example substantially perpendicular, with respect to the longitudinal axis H. The cap 23 comprises a transversal wall 24, which can have a substantially circular plan shape, and a skirt 25. The skirt 25 has a cylindrical tubular shape and is provided on an internal surface thereof with fixing means, not illustrated, by means of which the cap 23 can be fixed to a neck of a container. An interlayer 27 of secondary material 95 is present in the transversal wall 24, which interlayer 27 is sunken into the principal material 94. The interlayer 27 is obtained during the compression moulding, as the layer 97 of secondary material 95 of the multilayer dose 98 is crushed between the female moulding element 100 and the male moulding element 102 such as to form a single interlayer 27. In an alternative version, the layer 97 can originate a double interlayer of secondary material 95, at least in some regions of the transversal wall 24.

Since, in the multilayer dose 98, the distance dl between the layer 97 and the longitudinal axis H is relatively small, when the multilayer dose 98 is compression-moulded the secondary material 95 is confined internally of the transversal wall 24, i.e. it does not emerge onto an internal surface 29 nor onto an external surface 30 of the transversal wall 24.

Note that in the version shown in figure 28 the secondary material 95 is not present in the skirt 25. This is not negative, as certain types of secondary material 95, if arranged in the skirt 25, might make it fragile and reduce its mechanical properties, which might compromise the effectiveness of the fixing means in the skirt 25 for fixing the cap 23 to the container. To prevent the secondary material 95 from flowing towards the skirt 25 when the multilayer dose 98 is compression-moulded, the viscosity of the materials used can be altered, as described in the following with reference to figure 29. If the viscosity of the principal material 94 is lower than the viscosity of the secondary material 95, the principal material 94 will flow more rapidly between the female moulding element 100 and the male moulding element 102 with respect to the secondary material 95. This means that if we consider three points A, B and C arranged in the principal material 94 along an end surface 22 of the multilayer dose 98, and two points P and Q arranged in the secondary material 95 along the end surface 22, points A, B and C have a filling velocity v of the mould which is greater than the filling velocity w of the mould considered at point P and Q. The principal material 94 thus fills the forming chamber defined between the female moulding element 100 and the male moulding element 102 more rapidly than the secondary material 95. Consequently, the secondary material 95 is sunken in the principal material 94 and does not appear on any external surface of the cap 23, although, in the multilayer dose 98, the secondary material 95 had a first annular end 19 and a second annular end 20 emerging on the corresponding end surfaces. Both the multilayer doses in figures from 20 to 22 and the multilayer dose shown in figure 27 can be obtained by extruding the principal material and the secondary material through a coextrusion head 103 of the type shown schematically in figures 30 and 31. These figures show a half-section of the terminal part of the coextrusion head 103. The coextrusion head 103 has, in section, a non-illustrated portion arranged symmetrically to the section illustrated with respect to an extrusion axis E.

The coextrusion head 103 has a central passage 104 arranged along the extrusion axis E and destined to supply the principal material in an extrusion conduit 105. A peripheral passage 106, inclined with respect to the central passage 104, opens into the extrusion conduit 105 in a peripheral position with respect to the central passage 104. The peripheral passage 106 is also crossed by the principal material. An intermediate passage 107 is interposed between the central passage 104 and the peripheral passage 106, which intermediate passage 107 is inclined with respect to the central passage 104 and opens into the extrusion conduit 105, which enables the secondary material to be put into the extrusion conduit.

The coextrusion head 103 comprises an obturator 108, mobile parallel to the extrusion axis E between an open configuration, shown in figure 30, and a closed configuration, shown in figure 31, as indicated by the arrow F. In the open configuration the intermediate passage 107 is open and the secondary material can flow towards the extrusion conduit 105. In the closed configuration the obturator 108 closes the intermediate passage 107, with the consequence that the secondary material cannot reach the extrusion conduit 105. The central passage 104 and the peripheral passage 106 stay open all the time. In this way, the principal material is dispensed continuously while the secondary material is dispensed intermittently. This enables multilayer doses to be obtained, of the type shown in figures 12 and 22, in which at least an annular end of the secondary material does not reach as far as the corresponding end surface, but is sunken into the primary material. Naturally, one or both the annular ends of the secondary material can be sunken into the principal material, also in a multilayer dose of the type shown in figure 27, i.e. suited to forming caps rather than preforms. Alternatively, the dispensing of the secondary material can be interrupted by acting on the flows of the principal material and the secondary material, without there being a mobile obturator.

In a version which is not illustrated, instead of a single layer of secondary material, as shown in figures 20 to 22, and 27, several layers can be included, mutually distanced or in contact, at least partially sunk into the principal material. These layers, a number of which can be arbitrary, can be realised using different materials. For example, a first layer can comprise a barrier material while a second layer might comprise an adhesive material destined to improve the adhesion of the barrier material to the principal material. In this case the first layer and the second layer are in contact with each other. Alternatively, several layers of a same secondary material can be included, for example a barrier material, distanced from one another such as to improve the barrier properties of the moulded object without creating a single barrier layer having an excessive thickness. In a version which is not illustrated, applicable both to multilayer doses of figures from 20 to 22 and to the multilayer dose of figure 27, the thickness of the layer or layers of secondary material can be inconstant and may vary along the longitudinal axis H according to the type of moulded object to be obtained. By appropriately selecting the thickness of the secondary material such as to take account of the deformations which the various points of the multilayer dose are subject to when they are compression moulded, it can be ensured that the moulded object has a desired distribution of secondary material. For example, in this way the moulded object can have a uniform distribution of secondary material or a thickness of the secondary material which is always greater than a predetermined minimum. In order to obtain the non-uniform thickness of the secondary material in the multilayer dose, the flows of principal and secondary material can be adjusted inside the respective passages of the coextruder head 103.

Results such as those described above, as far as the distribution of the secondary material in the moulded object is concerned, can also be obtained by varying the distance of the layer of secondary material from the longitudinal axis H of the multilayer dose, i.e. providing a layer of secondary material a distance of which from the longitudinal axis H is variable such as to take account of the deformations that the various points of the dose must be subjected to in order to form the moulded object. Figures 32 and 33 show a portion of a coextruder device included in an apparatus for forming multilayer doses. The coextruder device comprises an extrusion conduit 115, a half of which is illustrated in figures 32 and 33, in which first supply means and second supply means open. The extrusion conduit 115 can extend in an extrusion direction E. The first supply means comprise a first supply conduit 116 through which a principal material 124 is conveyed towards the extrusion conduit 115. The second supply means comprise a second supply conduit 117 for sending a secondary material 125 into the extrusion conduit 115. The principal material 124 and the secondary material 125 can be of the same type as the principal material 4 and the secondary material 5 described above. An obturator 118 is mobile internally of the supply conduit 117, which obturator 118 can move between a raised position, shown in figure 32, and a lowered position, shown in figure 33. To move from the raised position to the lowered position or vice versa, the obturator 118 can slide in the extrusion direction E. In the raised position, the end of the second supply conduit 117 opening into the extrusion conduit 115 is open, such that the secondary material 125 can be sent into the extrusion conduit 115. On the contrary, in the raised position the obturator 118 closes the second supply conduit 117, preventing the secondary material 125 from entering the extrusion conduit 115.

Figures 39 and 40 illustrate two embodiments of the extrusion conduit 115, the first supply conduit 116 and the second supply conduit 117. As can be seen, the second supply conduit 117 extends along the extrusion direction E, while the first supply conduit 116, which can be annular in shape, is inclined with respect to the extrusion direction E. In both illustrated examples the first supply conduit 116 is inclined by 45° with respect to the second supply conduit 117, i.e. with respect to the extrusion direction E. The first supply conduit 116 surrounds the second supply conduit 117.

The extrusion conduit 115 comprises a diverging tract 119, interposed between an upstream tract 120 having a smaller transversal section and a downstream tract 121 having a larger transversal section. For example, the upstream tract 120 an the downstream tract 121 can be cylindrical in shape, in which case the diverging tract 119 is truncoconical.

It is however possible to have, for the upstream tract 120 and for the downstream tract 121, different shapes from the cylindrical, for example prismatic, should it be desired to obtain a multilayer dose having a non- circular transversal section. In this case, the shape of the diverging tract 119 will consequently have to be changed, such as to connect the upstream tract 120 and the downstream tract 121. The diverging tract 119 has an internal wall which forms an angle M with the extrusion direction E. In the example of figure 39, the angle M is about 32°, while in the example of figure 40 the angle M is about 31°. In general, the angle M can vary between 20° and 40°, in particular between 25° and 35°, and even more exactly between 30° and 35°. The diverging tract 119 can have a length comprised between 5 and 30 mm, in particular between 5 and 20 mm, more in particular between 5 and 15 mm. Li the example of figure 39, the diverging tract 119 has a length of 8 mm, while in the example of figure 40 the length is 5 mm. The upstream tract 120 has a substantially constant section and can have a variable length between 15 and 100 mm, in particular from 35 (figure 40) to 50 mm (figure 39). The transversal dimension of the upstream tract 120, i.e. its diameter, can vary from 5 to 20 mm, in particular from 5 to 15 mm, and more in particular from 8 mm (figure 39) to 12 mm (figure 40). The downstream tract 121 can have a variable length from 25 to 200 mm, in particular from 40 to 85 mm, more in particular from 50 to 75 mm. This last case is illustrated in figure 40, while in the example of figure 39 the length of the downstream tract 121 is 52 mm. The transversal dimension of the downstream tract 121, i.e. its diameter, can vary from 10 to 30 mm, in particular from 15 to 25 mm, more in particular from 15 to 20 mm. In both illustrated cases, the diameter of the downstream tract 121 is 18 mm.

It has been experimentally established that during functioning the coextruder device behaves as shown in figures from 34 to 38, which show a semisection of the extrusion conduit 115, the first supply conduit 116 and the second supply conduit 117.

Initially the obturator 118 is in the lowered position, such as to close the second supply conduit 117. In the upstream tract 120 of the extrusion conduit 115 only the principal material 124 is introduced, supplied via the first supply conduit 116. Thereafter, the obturator 118 is brought into the raised position, such as to open the second supply conduit 117. The secondary material 125 can then flow into the estrusion conduit 115 internally of a flow of principal material 124 which comes from the first supply conduit 116, which is always open. Since the first supply conduit 116 surrounds the second supply conduit 117, the secondary material 125 is positioned in a central region of the upstream tract 120, in proximity of the axis thereof, while the principal material 124 is positioned in a peripheral region of the upstream tract 120. In this way, the principal material 124 surrounds the secondary material 125 internally of the upstream tract 120 .

After a predetermined quantity of secondary material 125 has been dispensed, the obturator 118 is newly brought into the lowered position, such as to close the second supply conduit 117. In this way only the principal material 124 flows into the extrusion conduit 115. Thus internally of the upstream tract 120 a discrete portion 122 of secondary material 125 is formed, completely surrounded by the principal material 124. As illustrated in figure 34, internally of the upstream tract 120 the discrete portions 122 has the form of an elongate full body, for example substantially cylindrical or prismatic. The length of the upstream tract 120 is such as to enable a discrete portion 122 of secondary material 125 to be housed internally of the upstream tract 120. In other words, the upstream tract 120 has a length of the same order as the length of the discrete portion 122.

When the discrete portion 122 flows into the diverging tract 119 and thereafter into the downstream tract 121, its shape changes, as shown in figures from 35 to 38. Initially, a front region of the discrete portion 122 in the diverging tract 119 broadens, while the principal material 124 begins to penetrate internally of a posterior region of the discrete portion 122, as illustrated in figures 35 and 36. The discrete portion 122 thus transforms into a concave portion 123, half of which can be seen in figure 38, comprising a dome-shaped zone 126 from which a tubular body or mantle 131 departs, which can be diverging, the mantle 131 being delimited by an annular edge zone 127. The annular edge zone 127 is arranged posteriorly of the dome- shaped zone 126 with respect to the extrusion zone E. The concave portion 123 is completely sunk in the principal material 124. The discrete portion 122 transforms into the concave portion 123 thanks to the special shape of the extrusion conduit 115, and in particular thanks to the diverging tract 119. The rheological properties of the principal material 124 and the secondary material 125, typically plastic materials behaving as non- Newtonian fluids, also help the discrete portion 122 to assume the shape of the concave portion 123. Further, the concave portion 123 is formed more easily, by specially selecting the process conditions, in particular the temperature and the flow of the principal material 124 and the secondary material 125. For example, in the case shown in figure 39, the principal material 124 is blue high-impact polystyrene (HIPS), extruded through the first supply conduit 116 at a temperature of 21O⁰C and with a flow rate of 140 Kg per hour. The secondary material 125 is red high-impact polystyrene (HIPS), extruded at a temperature of 210⁰C.

In the case illustrated in figure 40, the principal material 124 is polyethylenetherephthalate (PET) having a temperature of 275⁰C, extruded with a flow rate of 450 Kg per hour. The secondary material 125 is an aromatic polyamide NMXD6 having a temperature of 275°C. By repeatedly opening and closing the obturator 118, it is possible to obtain, in the flow of principal material 125, a plurality of concave portions 123. The plastic material exiting from the extrusion conduit 115 is successively cut with a cutting device, not illustrated, such as to obtain a plurality of multilayer doses 128, one of which is shown in figure 41. The multilayer dose 128 comprises a body 136 which extends about a longitudinal axis H. The body 136 can have an elongate shape, for example cylindrical or prismatic and can have a length L in the direction of the longitudinal axis H. The body 136 is delimited by a first end 129 and a second end 130 opposite the first end 129, the first end 129 and the second end 130 being arranged transversally of the longitudinal axis H. The body 136 is mainly formed by the principal material 124 in which the concave portion 126 of secondary material 125 is sunken. The annular edge zone 127 is in an adjacent position to the first end 129, from which it is separated by a distance R. The dome-shaped zone 126 is arranged in an adjacent position to the second end 130.

The multilayer dose 128 is particularly useful for forming hollow objects by compression-moulding. The concave portion 123 has a shape which is quite similar to that which the secondary material 125 will assume in the moulded hollow object. In particular, thanks to the shape of the concave portion 123, the secondary material 125 can easily be distributed in an end wall and in a lateral wall of the moulded object. The distance R between the first end 129 and the annular edge zone 127 ensures that the secondary material 125 does not emerge onto the external surface of the moulded object and indeed is sufficiently far away from the surface. This is especially important should the moulded object be a preform for containers, comprising a lateral wall which is arranged about a longitudinal axis, an end wall and a mouth or neck in an opposite position to the end wall. The neck usually comprises fixing means, for example a thread, which engage with a container cap, and one or more annular projections in proximity of the fixing means. In order to prevent the secondary material 125 from weakening the preform at the neck thereof, the neck should be formed more or less entirely from the principal material 124. The distance R is thus chosen with the volume of the neck of the preform to be obtained in mind. Once the transversal dimension of the multilayer dose 128 has been defined, it is possible to calculate the distance R from the volume of the neck of the preform, which is such that the portion of the multilayer dose 128 interposed between the annular edge zone 127 and the first end 129 is sufficient to fashion the neck of the desired volume. It has been seen in testing that, considering the various types of preforms on the market, the above-described condition obtains when the distance R is variable between 5% and 50% of the length L, in particular between 5% and 30% of the length, and even more precisely between 5% and 20% of the length L. The secondary material 125 can have a non-constant thickness internally of the body 136, according to the type of object to be obtained from the multilayer dose 128 and the deformation which the secondary material 125 has to undergo when the multilayer dose 128 is processed to fashion a finished object. For example, if the multilayer dose 128 is to be fashioned to obtain a substantially cylindrical preform which successively by blow- forming or stretch-blowing will become an approximately cylindrical bottle, the mantle 131 can have a substantially constant thickness. In this case, the dome-shaped zone 126 can have a greater thickness than the thickness of the mantle 132, as the dome-shaped zone 126 is the portion of secondary material 125 which is most deformed and stretched to obtain the bottle.

In an alternative version, the plastic material exiting the extrusion conduit 15 can be cut not between each concave portion 123 and the following one, but between two or more adjacent concave portions, such that internally of a same multilayer dose there is more than one concave portion contained. For example, figure 42 shows a multilayer dose 138 comprising a body 146 extending along a longitudinal axis H, in which, internally of the principal material 124, a first quantity and a second quantity of secondary material 125 are positioned, distinct and separate from one another. The first quantity and the mass quantity can have respective the shapes of a first concave portion 133 and a second concave portion 143, arranged in sequence along the longitudinal axis H.

The multilayer dose 138 can become an object provided with two layers of secondary material 125, i.e. a number of layers of secondary material 125 corresponding to the number of concave portions present in the principal material 124. In this way the properties of the finished object can be improved. If for example the secondary material 125 is a barrier material, an object comprising two thin layers of barrier material normally has barrier properties which are better than a corresponding object comprising a single layer, though thicker, of barrier material. The number of quantities or concave portions sunken in the multilayer dose can be chosen arbitrarily, as can the distance between the quantities or concave portions. For example, figure 43 illustrates a multilayer dose 148 comprising a body 176 formed from the principal material 124, internally of which three distinct quantities of secondary material 125 are sunk, in the form of a first concave portion 153, a second concave portion 154 and a third concave portion 155. The concave portions 153, 154 and 155 of the multilayer dose 148 are arranged in sequence along the longitudinal axis H and are closer to one another than in the case illustrated in figure 34. Each concave portion is in face partially received internally of the concavity of the adjacent concave portion. In particular the second concave portion 154 has a dome-shaped zone 156 arranged internally of the concavity defined by the first concave portion 153, while the third concave portion 155 has a respective dome-shaped zone 157 received internally of the concavity of the second concave portion 154. By arranging the concave portions in close reciprocal positions, an arbitrary number of concave portions can be provided, even within a multilayer dose of short length in the longitudinal axial direction thereof.

In a version illustrated in figure 44, a multilayer structure 152 exits from the extrusion conduit 115 comprising a plurality of concave portions 123, formed from the secondary material 125, arranged in a sequence internally of the principal material 124. Multilayer doses 158 are severed from the multilayer substance 152, one of which is shown in figure 45, by cutting the multilayer structure along cutting lines 151 which pass through he concave portions 123. The cutting lines 151 are transversally arranged, in particular they are perpendicular with respect to a main direction G in which the multilayer structure 152 extends. Owing to the position of the cutting lines 151, each concave portion 123 is divided into two parts, which are arranged in two successive adjacent doses. Each multilayer dose 158 thus has a body 166 formed principally from the principal material 124, in which a first quantity 159 and a second quantity 160 of secondary material 125 are present, which quantities are distinct from one another. The first quantity 159 is dome-shaped and derives from the dome-shaped zone 126 of the concave portion 123. The second quantity 160 has the shape of a sleeve, which can be truncoconical, as in the example of figure 45, or prismatic, and derives from the mantle 131 of the concave portion 123 adjacent to the concave portion from which the first quantity 159 came. The first quantity 159 has an annular edge zone arranged on a first end surface 161 of the multilayer dose 158, while the second quantity 160 has a further annular edge zone present on a second end surface 162 of the multilayer dose 158, the second end surface 162 being opposite the first end surface 161. The body 166 of the multilayer dose 158 is usually elongate, for example cylindrical or prismatic.

The multilayer dose 158 can be used for obtaining hollow objects, for example preforms or containers, by compression moulding. Figure 45 schematically shows the multilayer dose 158 internally of a mould 39 which mould 39 is substantially identical to the mould shown in figure 13, which enables a preform 165 to be obtained from the multilayer dose 158, which preform 165 is shown in figure 46. When the multilayer dose 158 is compressed between the male moulding element 42 and the female moulding element 40, the part of the multilayer dose 158 which interacts first with the male moulding element 42 is the first end surface 161, the first quantity 159 being in proximity thereof. The first quantity 159 tends to remain in adherence to the male moulding element 42, which displaces the first quantity 159 towards the bottom of the forming cavity 41. In this way the first quantity 159 forms a first layer 167 of secondary material 125 positioned in the end wall 174 of the preform 165.

The second quantity 160, which is arranged in proximity of a lateral surface 164 of the multilayer dose 158, is positioned vertically between the female moulding element 40 and the male moulding element 42, such as to form a second layer 168 of secondary material 125 internally of the lateral wall 175 of the preform 165. Since the second quantity 160 has an annular end 163, opposite the second end surface 162, arranged at a certain distance from the first end surface 161, the secondary material 125 does not reach the neck 169 of the preform 165, but stops below an annular projection 170 included in the neck 169. The neck 169 is thus formed from the principal material 124. In the multidose layers shown in figures from 41 to 43, the secondary material has the shape of a concave portion comprising a tubular body or lateral mantle which can be diverging, for example truncoconical. According to the type of object to be obtained from the multilayer dose, the lateral mantle can also not be diverging. For example, in order to obtain objects having a low length-diameter ratio, such as caps, the diverging lateral mantle may not be necessary. Figures from 47 to 50 show different types of multilayer doses obtainable from one or more obturators of the type shown in figures 32 and 33. These doses comprise one or more quantities of secondary material 125 surrounded by the principal material 124. In figures from 47 to 50, the quantities of secondary material 125 are schematically represented as rectangular, but they can also be of different shapes, for example with concave portions similar to the concave portions 123, or spherical forms, drop-forms, ellipses and so on. Figure 47 shows a multilayer dose 178 having a single quantity 179 of secondary material 125 completely surrounded by the principal material 124. Figure 48 illustrates a multilayer dose 188 having a first quantity 189 and a second quantity 190, distinct from one another, of secondary material 125, the first and second quantities 189, 190 being arranged on opposite sides of the longitudinal axis H of the multilayer dose 188. Figure 49 shows a multilayer dose 198 in which two distinct quantities of secondary material 125 are immersed in the principal material 124. In particular, these quantities comprise a first quantity 199 and a second quantity 200 arranged in sequence along the longitudinal axis H. In the version of figure 50, a multilayer dose 208 comprises a principal material 124 internally of which three distinct quantities of secondary material 125 are sunk. A first quantity 209 is arranged in a central position, i.e. at the longitudinal axis H, in proximity of a first end 212 of the multilayer dose 208. A second quantity 210 and a third quantity 211 are arranged on opposite sides of the longitudinal axis H in proximity of a second end 213 of the multilayer dose 208.

Figure 51 shows a multilayer dose 218 internally of which a mass 219 of secondary material 125 is arranged. The mass 219 is completely surrounded by a layer 220 of a third material 221. The third material 221 is in turn completely surrounded by the principal material 124. In the version of figure 52, a multilayer dose 228 is provided in which the third material 221 surrounds only a lateral surface zone 229 of the mass 219 of secondary material 125. A first end surface 230 and a second end surface 231 of the mass 219 are directly in contact with the principal material 124. The whole formed by the secondary material 125 and the third material 221 is completely surrounded by the principal material 124.

In a version which is not illustrated, a third supply conduit can be inserted after the downstream tract 121 of the extrusion conduit 115. The third supply conduit can be used for introducing, in the flow of plastic material which flows along the extrusion conduit 115, additional quantities of principal material 124, either continuously or intermittently. In this way the flow of plastic material can be modelled in the desired geometry and can interact with the discrete portions of secondary material 125 in order to give these portions a different shape from the concave shape.

The obturator 118 shown in figures 32 and 33 can be kept constantly open, such as to dispense the secondary material 125 continuously. This enables multilayer doses to be provided in which the secondary material 125 forms a solid mass, i.e. not hollow, for example cylindrical, surrounded by an external lateral layer of secondary material 124. Multilayer doses of this type might be used for obtaining objects such as caps and seals, similarly to what is described with reference to figures 26 and 28. Multilayer compression-moulded objects can also be obtained using the Layer Multiplier System technology. In this case, the moulded object comprises a first material and a second material, the second material being produced using the Layer Multiplier System technology.

The Layer Multiplier System technology starts from a composite structure comprising, for example, two relatively thick layers formed from two different materials. These layers are subdivided several times, superposed and reprocessed up to obtaining a desired multilayer composite. The Layer Multiplier System technology is described, for example, in United States patent US5094793. A multilayer object of the above-described type can be produced starting from multilayer doses such as those described herein above, in which the second material has a geometric conformation which is similar to those of the secondary material. In such doses, the first material is of the same type as the principal material 4 described herein above.

The multilayer object thus obtained can be a preform, a cap, a container, a seal, a container neck, or another object. Figure 53 shows a multilayer dose 238 comprising a first material, or principal material, forming a central nucleus 239, which can have an elongate shape, for example cylindrical or prismatic. The central nucleus 239 can be realised using a completely similar material to the principal material 4 described herein above, A tubular-shaped external layer 240 is arranged about the central nucleus 239, comprising a material obtained using Layer Multiplier System technology.

The external layer 240 can be of the same length as the central nucleus 239.

The external layer 240 and the central nucleus 239 can be obtained by coextrusion. The material which forms the external layer 240, as shown in the enlarged detail of figure 53, can comprise a matrix material 241 in which a plurality of layers 242 is contained, realised in a different material from the matrix material, for example the secondary material 15 described herein above.

The layers 242 give the external layer good barrier properties, as they function as obstacles for any oxygen molecules, water or other substances which attempt to move from one part to the other of the external layer 240.

In a version which is not illustrated, between each layer 242 and the matrix material 241 an adhesive material can be interposed, which improves the adhesion between the layers 242 and the matrix material 241. In the version shown in figure 53, the external layer 240 has a constant thickness. However, as shown in figure 54, a multilayer dose 248 can be provided which is the same as the one in figure 53, but comprising an external layer 250 having a non-constant thickness, for example an external layer 250 the thickness of which grows linearly passing from one end to another of the multilayer dose 248. The non-constant thickness of the external layer 250 can be chosen such as to take account of the deformations the external layer 250 undergoes during the compression-moulding of the multilayer dose 248, such that the material forming the external layer 250 is distributed uniformly in the moulded object. In a version, a preform can be provided having a body entirely formed from a material obtained by Layer Multiplier System technology. The preform can be compression-moulded.

All the multilayer doses described herein above can have a secondary material of a nanocompound nature. The nanocompound materials used can be inorganic materials such as phyllosilicates, associated for example to compatibilising substances. The inorganic materials and any compatibilising substances can be dispersed in a polymer matrix. The compatibilising substances make the inorganic materials compatible with the polymer matrix. To obtain a compression-moulded multilayer object, instead of starting from a multilayer dose it is possible to use a plurality of doses made from different materials.

For example, in the version of figure 55, a first dose 252 made of a principal material and a second dose 253 made of a secondary material are deposited internally of a female mould 251, contemporaneously or in sequence. The principal material and the secondary material can comprise the same materials previously listed with reference to the principal material 4 and the secondary material 5. The second dose 253, which can have a smaller volume than the first dose 252, is positioned above the first dose 252. In an alternative version, shown in figure 56, apart from the first dose 252 and the second dose 253, a third dose 254 of principal material is inserted. The second dose 253 is in this case interposed between the first dose 252 and the third dose 254.

Finally, in a further alternative version, shown in figure 57, two doses of principal material 255 and two doses of secondary material 256 are introduced internally of the female mould 251. The doses of secondary material 256 are interposed between the doses of principal material 255. The doses of secondary material 256 are further distanced from one another, such as to be positioned in two opposite regions arranged in proximity of an internal lateral surface of the female mould 251. Many other arrangements and numbers of doses of primary or secondary material, and possibly also other additional materials, can be included for realising compression-moulded objects having a desired geometry. In particular, all the multilayer doses described and illustrated can comprise a number of materials which is greater than two, i.e. they can be formed not only from two but also from three or more materials that are different from one another. Apart from the principal material and the secondary material, there can be for example at least an adhesive material to cause the principal material to adhere to the secondary material.

Figure 58 shows a cap 313 comprising an end wall 314 which can have a circular plan shape. A skirt or lateral wall 315 projects from the end wall, being shaped for example as a hollow cylinder. The lateral wall 315 has, on an internal surface thereof, fixing means for fixing the cap 313 to a container neck, which can comprise for example a threaded portion 312. An intrusion-proof security ring 317 is connected to the lateral wall 315, which ring 317 is arranged at an end of the lateral wall 315 opposite the end wall 314. The security ring 317 is connected to the lateral wall 315 by means of a plurality of bridge elements 322, visible in figure 58. When the cap 313 is arranged on a container neck, the security ring 317 is below a collar fashioned on the neck. When the container is opened for the first time, the security ring 317 engages with the collar and detaches from the lateral wall 315 of the cap 313 because the bridge elements 22 break. The security ring 317, if detached from the lateral wall 315, informs the consumer that the container has already been opened.

A seal lip 324 projects internal wise of the cap 313 from the end wall 314. In use, the seal lip 324 is destined to engage with the container neck to sealingly close the container. The seal lip 324 extends circumferentially internally of the end wall 314. One or more annular projections can be present between the end wall 315 and the seal lip 324 and project from the end wall 314 .

The cap 313 can be made of a plastic material, for example obtained by injection moulding or compression moulding, or can be made of metal. As shown in figure 67, a disc element 300 is formed internally of the cap 313, which disc element 300 adheres to an internal surface of the end wall 314 and faces towards the inside of the container during use. The disc element 300, which can have a circular plan shape, is surrounded by the seal lip 324. The disc element 300 can comprise a flat central region and an annular protrusion 301 which projects from the flat central region towards the inside of the cap 313. The annular protrusion 301 can adhere to an internal surface of the seal lip 324 and can be of the same height as the seal lip 324.

The disc element 300 has a multilayer conformation, as will be described in detail herein below. The disc element 300 can be obtained by compression-moulding, internally of the cap 313, a multilayer dose 308 of the type shown, in enlarged scale, in figure 59. In the illustrated example, the multilayer dose 308 has a cylindrical shape, but it is possible also to use a multilayer dose having a parallelepiped shape or, more generally, a prismatic shape.

The multilayer dose 308 comprises a principal material 304, which can be one of the plastic materials previously denoted, describing the principal material 4, possible with an addition of oxygen scavenging substances. A secondary material 305 is arranged internally of the principal material 304, the secondary material 305 being a functional material, i.e. provided with a desired functionality, for example having gas or vapour barrier properties. The secondary material 305 can be one or the previously-indicated materials for the secondary material 5 and possibly can comprise an oxygen scavenging substance. The secondary material 305 can form, internally of the multilayer dose 308, a tubular layer, particularly a cylindrical layer. The principal material 304 is arranged both internally and externally of the secondary material 305. The tubular layer of secondary material 305 can have respective ends arranged on external surfaces of the dose. Alternatively, only an end of the tubular layer can be arranged on an external surface of the dose, or the secondary material 305 can be completely sunk in the principal material 304. A compatibilising material 306 can be interposed between the secondary material 305 and the principal material 304, which compatibilising material 306 is destined to improve the adhesion between the principal material 304 and the secondary material 305. In the illustrated example, two layers of compatibilising material 306 are included, arranged respectively internally and externally of the secondary material 305. The multilayer dose 308 is obtained by cutting a multilayer structure exiting from a coextruder device. A transferring device, not illustrated, conveys the multilayer dose 308 from the coextruder device towards the cap 313. The multilayer dose 308 is thus deposited internally of the cap 313, such as to be supported by the end wall 314, as shown in figures 60 and 61.

The multilayer device 308 deposited in the cap 313 has the same number of layers as the multilayer structure exiting the coextruder device. In other words, during the transfer of the coextruder device to the cap 313 the multilayer dose 308 is not subject to variations in the number of layers which make it up.

The cap 313 the multilayer dose 308 is deposited in is supported by a support device, not illustrated, on which an external surface of the end wall 314 rests. The multilayer dose 308 is deposited about in the centre of the end wall 314 such that a longitudinal axis of the multilayer dose 308 is substantially parallel to the end wall 314.

As shown in figure 62, the cap 313 interacts thereafter with a punch element 302 which shapes the multilayer dose 308. The punch element 302 comprises a central nucleus 303 which extends along a moulding axis Yl and which is delimited by a forming surface 307 which substantially flat. The punch element 302 further comprises a sleeve 309, arranged about the central nucleus 303. The sleeve 309 is delimited by a front surface 310 having a complementary shape to the shape of the seal lip 324. The central nucleus 303 and the sleeve 309 are mobile with respect to one another. Also included are movement means for moving the support device that supports the cap 313 and the punch element 302 with respect to one another. The movement means can for example comprise an actuator which moves the support device on which the cap 313 is rested with respect to the punch element 302.

After the multilayer dose 308 has been introduced into the cap 313, the movement means move, for example, the cap 313 towards the punch element 302. In the situation of figure 62, the multilayer dose 308 is in contact with the forming surface 307 of the central nucleus 303, which however has not yet started to deform the multilayer dose 308.

As it continues to move the cap 313 towards the punch element 302, the seal lip 324 strikes against the front surface 310 of the sleeve 309 and engages snugly and couplingly with the surface. Thus a closed chamber 311 is defined between the punch element 302 and the cap 313, which closes the multilayer dose 308 and has a greater volume than that of the dose. In the meantime, the multilayer dose 308 begins to be crushed by the punch element 302. The multilayer dose 308 thus assumes an approximative parallelepiped shape, as shown in figures 63 and 64.

Figures 65 and 66 show a successive stage of the moulding process by compression of the multilayer dose 308. In this stage, the cap 313 has further neared the punch element 302. While the sleeve 309 has stayed in contact with the seal lip 324, the distance between the central nucleus 303 and the end wall 314 has been reduced, such as to reduce the volume of the closed chamber 311. The multilayer dose 308 has taken on the shape of a circular disc which almost entirely occupies the closed chamber 311. The movement means continue to move the cap 313 towards the punch element 302 up until the multilayer dose 308 completely fills the closed chamber 311, the volume of which is progressively reduced. In this way the disc element 300 of figure 61 is obtained internally of the cap 313. The disc element 300 adheres to the end wall 314 thanks to microfusion phenomena which occur on the internal surface of the end wall 314, when the hot plastic material forming the multilayer dose comes into contact with the end wall 314. The adhesion of the disc element 300 to the end wall 314 of the cap 313 can be improved by mechanical elements included in the cap 313. These mechanical elements can be, for example, channels or recesses afforded on the end wall 314, or can consist in a special surface finishing, suitably roughened, of the end wall 314. As can be seen in the enlargement of figure 61, the disc element 300 comprises a first external layer 316, adhering to the end wall 314 of the cap 313. The disc element 300 further comprises a second external layer 318 which during use faces the inside of the container which is closed by the cap 313. Both the first external layer 316 and the second external layer 318 are formed by the principal material 304 which was arranged externally of the secondary material 305 of the multilayer dose 308. Thus the first external layer 316 and the second internal layer 318 have the same composition. At least an internal layer of secondary material 305 is interposed between the first external layer 316 and the second external layer 318. In the illustrated example, the secondary material 305 forms a first layer 319 and a second layer 320 separated by an intermediate layer 321 of principal material 304. The first layer 319 and the second layer 320 derive from the tubular layer of secondary material 305 included in the multilayer dose 308. This tubular layer has been crushed such as to form two substantially flat layers which, as shown in figure 67, are joined to one another in a peripheral region 323 of the disc element 300. The disc element 300 further comprises slim layers 325 of compatibilising material 306 interposed between the principal material 304 and the secondary material 305 .

The disc element 300 can have a symmetrical structure with respect to a plane passing through the disc element 300 parallel to the end wall 314.

Thanks to the secondary material's 305 having barrier properties, the disc element 300 prevents the substances present in the container from exiting through the end wall 314 of the cap 313 and the substances in the external environment from entering the container and contaminating the respective contents.

The first external layer 316 and the second external layer 318 prevent the secondary material 305 from coming into contact with the product contained in the container which might be contaminated by certain types of secondary material. Finally, by manufacturing the disc element 300 by compression-moulding, very slim disc elements can be formed and wasting of principal and/or secondary material can be avoided.

Figure 68 shows a multilayer dose 328 in a further version, which can be used for forming a disc element 300 of the type shown in figure 67. The multilayer dose 328, which can be cylindrical or parallelepiped, comprises a solid central body 326 of secondary material 305, surrounded by a tubular body 327 made of principal material 304. The compatibilising material 306 can be interposed between the principal material 394 and the secondary material 305, which compatibilising material 306 forms an intermediate layer 321 shaped as a slim tubular layer.

The multilayer dose 328 comprises a much greater quantity of secondary material 305 than the multilayer dose 308 of figure 59 and can be used when very good barrier properties are required. When the multilayer dose 328 is compression-moulded, a disc element having a single internal layer of secondary material 305 is obtained, interposed between a first external layer and a second external layer of principal material 304. Figures from 69 to 73 illustrate a process for forming a disc element 330, visible in figure 73, internally of a cap 333 of an alternative version. The cap 333 differs from the cap 313 shown in figure 62 as it comprises an end wall 334 having a substantially flat internal surface, i.e. without the seal lip 324. The cap 333 sealingly engages with a corresponding container neck thanks to a seal element 329 fashioned on the disc element 330. The seal element 329 extends circumferentially along a peripheral region of the whole disc element 330 and can be shaped as one or more annular swellings which project towards the inside of the cap 333. In the illustrated case, the seal element 329 comprises two annular swellings which act as seal lips. The disc element 330 is obtained by compression-moulding of a multilayer dose which can be of the type shown in figure 59 or in figure 68. In the illustrated example, a multilayer dose 308 is represented having a same conformation as the one illustrated in figure 59 and obtained as described with reference to figure 59. After having been severed from the coextruder device, the multilayer dose 308 is transferred into the cap 33, as shown in figure 69, such as to be rested on an internal surface of the end wall 334.

As shown in figure 70, the cap 333 is then moved towards the punch element 302, or vice versa, such that the multilayer dose 308 is shaped by the punch element 302.

The punch element 302 comprises, in this case, a central nucleus 343 having a forming surface 337 which is shaped such as to form the seal element 329 of the disc element 330. In particular, the forming surface 337 can have at least an annular recess destined to form a lip of the seal element 329. The central nucleus 343 is arranged internally of a sleeve 339 destined to strike against the end wall 334 in order to define the closed chamber 311, as shown in figure 71. In figure 71, the cap 333 and the punch element 302 have reached a relative position in which the central nucleus 343 has begun to deform the multilayer dose 308, which has taken on a substantially parallelepiped configuration. When the cap 333 moves further towards the punch element 302, or vice versa, the volume of the closed chamber 311 reduces further and the multilayer dose 308 takes on a substantially flat configuration, as shown in figure 72. When the multilayer dose 308 has completely filled the closed chamber 311, the disc element 330 has been obtained and the cap 333 and the punch element 302 can be distanced from one another. The disc element 330 has a multilayer conformation which is entirely similar to the disc element 300 shown in figure 67. As illustrated in figure 73, the secondary material 305 can have a flat geometry and can extend substantially over the whole area, in plan view, of the disc element 330. Thanks to its geometry, the disc element 330 acts not only as a barrier to gas and in particular oxygen, but also has a hydraulic seal action for the liquid contained in the container closed by the cap 333.

The disc elements shown in figures 67 and 73 can be obtained with a process that is similar to the one shown in figure 1, i.e. in which the multilayer dose exits from the coextruder device in a transversal outlet direction, for example perpendicular, and a moulding direction along which the cap and the punch element are reciprocally mobile.

Claims

Claims.

1). A method comprising stages of: dispensing a multilayer dose (68, 78, 88) comprising a principal material (64) delimited by an external lateral surface (74) and a secondary material (65) which is at least partially contained within the principal material (64), the secondary material (65) having a tubular conformation; compression-moulding the multilayer dose (68, 78, 88) in order to obtain an object (73) having a multilayer wall (55); characterised in that a distance (D) between the secondary material (65) and the external lateral surface (74) in the multilayer dose (68, 78, 88) is less than or equal to a thickness of the multilayer wall (55).

2). The method of claim 1, wherein the distance (D) is less than 4 mm.

3). The method of claim 1 or 2, wherein the distance (D) is less than 2 mm.

4). The method of one of claims from 1 to 3, wherein the object is a preform

(73) for a container.

5). The method of claim 4, wherein the multilayer wall is a lateral wall (55) of the preform (73).

6). The method of claim 4 or 5, wherein the preform (73) comprises an end wall (54), the end wall (54) having a central region which does not contain the secondary material (65).

7). The method of claim 6, wherein the central region extends about a longitudinal axis (Z) of the preform (73). 8). The method of claims from 4 to 6, wherein the preform (73) comprises a mouth (56), the mouth (56) being without the secondary material (65).

9). The method of claims from 4 to 8, wherein the secondary material (65) forms an intermediate layer (57) which extends along 80% or less of a length

(Ll) of the preform (73).

10). The method of one of claims from 1 to 9, wherein the multilayer dose

(68, 78, 88) has a substantially cylindrical shape.

11). The method of one of claims from 1 to 9, wherein the multilayer dose

(68, 78, 88) has a substantially prismatic shape.

12). The method of one of claims from 1 to 11, wherein, within the multilayer dose (68, 78, 88), the principal material (64) is arranged internally and externally of the secondary material (65).

13). The method of one of claims from 1 to 12, wherein within the multilayer dose (68, 78, 88), the secondary material (65) exhibits a hollow substantially cylindrical shape.

14). The method of one of claims from 1 to 13, wherein the multilayer dose

(68, 78), exhibits an end surface (72) on which an annular end (60, 70) of the secondary material (65) is present.

15). The method of claim 14, wherein the multilayer dose (68) has a further end surface (71) on which a further annular end (70) of the secondary material (65) is present.

16). The method of one of claims from 1 to 13, wherein, in the multilayer dose (88), the secondary material (65) has two annular ends (89, 90) sunken internally of the principal material (64).

17). The method of one of claims from 1 to 16, wherein the object (73) is obtained by compression-moulding of the multilayer dose (68, 78, 88) between first forming means (40) and second forming means (42), the first foraiing means (40) and the second forming means (42) being reciprocally mobile along a moulding direction (Y).

18). The method of claim 17, wherein the moulding direction (Y) is vertical.

19). The method of claim 17 or 18, wherein the multilayer dose (68, 78, 88) is extruded in an extrusion direction (X) which is substantially parallel to the moulding direction (Y).

20). The method of one of claims from 1 to 19, wherein the dose (68, 78, 88) exhibits an axis (H).

21). The method of claim 20, when depending on one of claims from 17 to

19, wherein the axis (H) is substantially parallel to the moulding direction

(Y).

22). The method of claim 20 or 21, wherein, within the multilayer dose (68, 78, 88), the secondary material (65) forms a layer having a variable thickness along the axis (H).

23). The method of one of claims from 10 to 12, wherein within the multilayer dose (68, 78, 88) the secondary material (65) forms a layer having a non-constant distance from the axis (H).

24). The method of one of claims from 17 to 19, or of one of claims from 20 to 23, when claim 20 depends on one of claims from 17 to 19, wherein after a stage of dispensing, the multilayer dose (68, 78, 88) is conveyed towards the first forming means (40) and towards the second forming means (42). 25). The method of one of claims from 1 to 24, wherein the principal material (64) is selected from a group comprising: polyethylenetherephthalate (PET), polypropylene (PP), polyvinylchloride (PVC), polyethylene (PE), polyethylene naphthalate (PEN), polystyrene (PS) or lactic polyacid (PLA). 26). The method of one of claims from 1 to 25, wherein the secondary material (65) is selected from a group comprising: a plastic material provided with a barrier property to oxygen, a plastic material provided with a barrier property to smells, a plastic material provided with a barrier property to moisture, a plastic material provided with a barrier property to light, a recycled plastic material, nano-compounds, a material of a same type as the principal material (64) with added colorant substances.

27). The method of one of claims from 1 to 26, wherein the multilayer dose

(68, 78, 88) comprises a third material interposed between the principal material (64) and the secondary material (65) in order to facilitate adhesion between the principal material (64) and the secondary material (65).

28). A multilayer dose for obtaining an object (73), comprising a principal material (64) delimited by an external lateral surface (74) and a secondary material (65) forming a tubular layer (67) extending about an axis (H) of the multilayer dose (68, 78, 88), characterised in that the distance (D) between the tubular layer (67) and the external lateral surface (74) is less than 4 mm.

29). The multilayer dose of claim 28, wherein the distance (D) is less than 2 mm.

30). The multilayer dose of claim 28 or 29, having an elongate body (66) such as to form, after having been compression-moulded, a preform (73) for a container.

31). The multilayer dose of one of claims from 28 to 30, having a substantially cylindrical shape.

32). The multilayer dose of one of claims from 28 to 30, having a substantially prismatic shape.

33). The multilayer dose of one of claims from 28 to 32, wherein the principal material (64) is arranged internally and externally of the secondary material

(65). 34). The multilayer dose of one of claims from 28 to 33, wherein the secondary material (65) has a hollow substantially cylindrical shape.

35). The multilayer dose of one of claims from 28 to 34, having an end surface (72) on which an annular end (60, 70) of the secondary material (65) is present.

36). The multilayer dose of claim 35, having a further end surface (71) on which a further annular end (70) of the secondary material (65) is present.

37). The multilayer dose of one of claims from 28 to 34, wherein the secondary material (65) has two annular ends (89, 90) sunken into the principal material (64).

38). The multilayer dose of one of claims from 28 to 37, wherein the principal material (64) is selected from a group comprising: polyethylenetherephthalate

(PET), polypropylene (PP), polyvinylchloride (PVC), polyethylene (PE), polyethylene naphthalate (PEN), polystyrene (PS) or lactic polyacid (PLA).

39). The multilayer dose of one of claims from 28 to 38, wherein the secondary material (65) is selected from a group comprising: a plastic material provided with a barrier property to oxygen, a plastic material provided with a barrier property to smells, a plastic material provided with a barrier property to moisture, a plastic material provided with a barrier property to light, a recycled plastic material, nano-compounds, a material of a same type as the principal material (64) with added colorant substances.

40). The multilayer dose of one of claims from 28 to 39, wherein the tubular layer (67) has a variable thickness along the axis (H).

41). The multilayer dose of one of claims from 28 to 40, wherein the tubular layer (67) has a variable distance from the axis (H).

42). The multilayer dose of one of claims from 28 to 41, and further comprising a third material interposed between the principal material (64) and the secondary material (65) in order to facilitate adhesion between the principal material (64) and the secondary material (65). 43). A method comprising a stage of compression-moulding a multilayer dose (98) between first forming means (100) and second forming means (102) which are reciprocally mobile in a moulding direction (Y), the multilayer dose (98) comprising a body (96) having an axis (H), the body (96) comprising a principal material (94) delimited by an external lateral surface (84) and a secondary material (95) forming a layer (97) which is at least partially embedded into the principal material (94), wherein a distance (dl) between said layer (97) and said axis (H) is comprised between 10% and 50% of the distance (d2) between said axis (H) and the external lateral surface (84), characterised in that the moulding direction (Y) is transversal with respect to said axis (H) during the stage of compression moulding. 44). The method of claim 43, wherein the moulding direction (Y) is substantially perpendicular to said axis (H) during the stage of compression- moulding.

45). The method of claim 43 and 44, wherein the moulding direction (Y) is substantially vertical.

46). The method of one of claims from 43 to 45, wherein during the stage of compression moulding the axis (H) is substantially horizontal. 47). The method of one of claims from 43 to 46, wherein the dose (98) has a substantially cylindrical shape.

48). The method of one of claims from 43 to 46, wherein the dose (98) has a substantially prismatic shape.

49). The method of one of claims from 43 to 48, wherein the layer (97) has a tubular conformation, the principal material (94) being arranged internally and externally of the layer (97). 50). The method of one of claims from 43 to 48, wherein the layer (97) is flat.

51). The method of claim 50, wherein the secondary material (95) forms a further layer arranged in a symmetrical position to the layer (97) with respect to the axis (H).

52). The method of one of claims from 43 to 51, wherein during the stage of compression-moulding, a forming chamber is defined between the first forming means (100) and the second forming means (102), internally of which forming chamber an object (23) is formed.

53). The method of claim 52, wherein the principal material (94) flows into the forming chamber more rapidly than the secondary material (95), such as to surround the secondary material (95) in order to obtain an object (23) in which the secondary material (95) is sunk in the principal material (94).

54). The method of claim 52 or 53, wherein the object is a cap (23) for a container.

55). The method of claim 54, wherein the forming chamber comprises a portion in which a transversal wall (24) of the cap (23) is formed, and a further portion in which a skirt (25) of the cap (23) is formed, the principal material (94) flowing from the portion towards the further portion more rapidly than the secondary material (95), such that the skirt (25) is substantially without the secondary material (95).

56). The method of one of claims from 43 to 55, wherein the principal material (94) is selected from a group comprising: polyethylenetherephthalate

57). The method of one of claims from 43 to 56, wherein the secondary material (95) is selected from a group comprising: a plastic material provided with a barrier property to oxygen, a plastic material provided with a barrier property to smells, a plastic material provided with a barrier property to moisture, a plastic material provided with a barrier property to light, a recycled plastic material, nano-compounds, a material of a same type as the principal material (94) with added colorant substances.

58). The method of one of claims from 43 to 57, wherein the dose (98) comprises a third material interposed between the principal material (94) and the secondary material (95) in order to facilitate adhesion between the principal material (94) and the secondary material (95).

59). An apparatus for forming multilayer doses (128, 158) comprising first supply means (116) for supplying a principal material (124) into an extrusion conduit (115) and second supply means (117) for supplying discrete portions

(122) of a secondary material (125) into a flow of the principal material (124) in the extrusion conduit (115), characterised in that the extrusion conduit

(115) comprises a tract (120) having a substantially constant section followed by a diverging tract (119) for deforming the discrete portions (122) such as to transform each discrete portion (122) into a concave portion (123) embedded in the principal material (124).

60). The apparatus of claim 59, wherein the tract (120) is of a length which is at least equal to a length of a discrete portions (122), such that the tract (120) can house a complete discrete portion (122).

61). The apparatus of claim 59 or 60, wherein the tract (120) is of a length which is variable between 15 mm and 100 mm.

62). The apparatus of one of claims from 59 to 61, wherein the tract (120) has a length which is variable between 35 mm and 50 mm.

63). The apparatus of one of claims from 59 to 62, wherein the tract (120) has a transversal dimension which is variable from 5 mm to 20 mm. 64). The apparatus of one of claims from 59 to 63, wherein the tract (120) has a transversal dimension which is variable from 5 mm to 15 mm.

65) The apparatus of one of claims from 59 to 64, wherein the tract (120) has a transversal dimension which is variable from 5 mm to 12 mm.

66). The apparatus of one of claims from 59 to 65, wherein the tract (120) is prismatic.

67). The apparatus of one of claims from 59 to 65, wherein the tract (120) is cylindrical.

68). The apparatus of one of claims from 59 to 67, wherein the diverging tract

(119) is truncoconical.

69). The apparatus of one of claims from 59 to 68, wherein the diverging tract

(119) has an internal wall which forms an angle (M) with an axis of the extrusion conduit (115), the angle being variable between 20° and 40°.

70). The apparatus of claim 69, wherein the angle (M) is variable between

25° and 35°.

71) The apparatus of claim 69 or 70, wherein the angle (M) is variable between 30° and 35°.

72). The apparatus of one of claims from 59 to 71, wherein the diverging tract

(119) is of a length which is variable between 5 mm and 30 mm.

73). The apparatus of one of claims from 59 to 72, wherein the diverging tract

(119) is of a length which is variable between 5 mm and 20 mm.

74). The apparatus of one of claims from 59 to 73, wherein the. diverging tract

(119) is of a length which is variable between 5 mm and 15 mm.

75). The apparatus of one of claims from 59 to 74, wherein the extruding conduit (115) comprises a further tract (121) arranged downstream of the diverging tract (119), the further tract having a transversal section which is substantially constant. 76). The apparatus of claim 75, wherein the further tract (121) is cylindrical.

77). The apparatus of claim 75 or 76, wherein the further tract (121) is of a length which is variable between 25 mm and 200 mm.

78). The apparatus of one of claims from 75 to 77, wherein the further tract

(121) is of a length which is variable between 40 mm and 85 mm.

79). The apparatus of one of claims from 75 to 78, wherein the further tract

(121) is of a length which is variable between 50 mm and 75 mm.

80). The apparatus of one of claims from 75 to 79, wherein the further tract

(121) is of a length which is variable between 10 mm and 30 mm.

81). The apparatus of one of claims from 75 to 80, wherein the further tract

(121) has a transversal dimension which is variable between 15 mm and 25 mm.

82). The apparatus of one of claims from 75 to 81, wherein the further tract

(121) has a transversal dimension which is variable between 15 mm and 20 mm.

83). The apparatus of one of claims from 59 to 82, wherein the first supply means comprise a first supply conduit (116) which extends about a second supply conduit (117) included in the second supply means.

84). The apparatus of claim 83, wherein the first supply conduit (116) is inclined by about 45° with respect to the second supply conduit (117).

85). The apparatus of claim 83 or 84, wherein the second supply conduit

(117) is coaxial with respect to the extrusion conduit (115).

86). The apparatus of one of claims from 59 to 85, and comprising an obturator device (118) for selectively opening and closing the second supply means (117). 87). The apparatus of one of claims from 59 to 86, and further comprising a cutting device for severing the doses (128, 158) from the flow at the outlet of the extrusion conduit (115).

88). A method for forming multilayer doses (128, 158) comprising stages of: supplying a principal material (124) into an extrusion conduit (115) having a tract (120) with a substantially constant section following by a diverging tract

(119); dispensing discrete portions (122) of a secondary material (125) internally of a flow of the principal material (124) into the extrusion conduit (115), wherein the discrete portions (122) are deformed in the diverging tract (119) such as to transform each discrete portion (122) into a concave portion (123) embedded in the principal material (124).

89). The method of claim 88, wherein each discrete portion (122), after having been dispensed, flows along the tract (120) which contains a whole length of the discrete portion (122). '

90). The method of claim 88 or 89, wherein each discrete portion (122) in the tract (120) takes on a shape of a solid elongate body of the secondary material

(125).

91). The method of one of claims from 88 to 90, wherein each discrete portion (122) in the tract (120) takes on a shape of a solid elongate body of a cylindrical body.

92). The method of one of claims from 88 to 91, wherein the tract (120) is of a length which is variable between 15 mm and 100 mm.

93). The method of one of claims from 88 to 92, wherein the tract (120) is of a length which is variable between 35 mm and 50 mm.

94). The method of one of claims from 88 to 93, wherein the flow runs in the extrusion conduit (115) along an extrusion direction (E). 95). The method of claim 94, wherein the concave portion (123) has a tubular body (131) which is closed at an end thereof by a dome-shaped zone (126), the tubular body (131) being arranged downstream of the dome-shaped body

(126) with respect to the extrusion direction (E).

96). The method of claim 95, wherein the dome-shaped zone (126) is formed in the diverging tract (119).

97). The method of claim 95 or 96, wherein the tubular body (131) extends into a further tract (121) of the extrusion conduit (115) downstream of the diverging tract (119).

98). The method of one of claims from 95 to 97, wherein the tubular body

(131) is divergent along the extrusion direction (E).

99). The method of one of claims from 88 to 98, wherein downstream of the diverging tract (119) the principal material (124) is further supplied into the flow.

100). The method of one of claims from 88 to 99, further comprising a stage of cutting the multilayer doses (128, 158) from the flow.

101). The method of claim 100, wherein the flow is cut between two successive concave portions (123), such that each multilayer dose (128) comprises a whole concave portion (123).

102). The method of claim 100, wherein the flow is cut at a discrete portion

(123) in order to generate two quantities (159, 160) of secondary material

(125) included in two consecutive doses (258) from the discrete portion

(123).

103). The method of one of claims from 88 to 102, wherein the principal material (124) is selected from a group comprising: polyethylenetherephthalate (PET), polypropylene (PP), polyvinylchloride (PVC)₅ polyethylene (PE), polyethylene naphthalate (PEN), polystyrene (PS) or lactic polyacid (PLA).

104). The method of one of claims from 88 to 103, wherein the secondary material (125) is selected from a group comprising: a plastic material provided with a barrier property to oxygen, a plastic material provided with a barrier property to smells, a plastic material provided with a barrier property to moisture, a plastic material provided with a barrier property to light, a recycled plastic material, nano-compounds, a material of a same type as the principal material (124) with added colorant substances. 105). The method of one of claims from 88 to 104, wherein the multilayer doses (128; 158) comprise a third material interposed between the principal material (124) and the secondary material (125) in order to facilitate adhesion between the principal material (124) and the secondary material (125). 106). The method of one of claims from 88 to 166, and further comprising a stage of compression-moulding the multilayer doses (128, 158) in order to obtain a preform of a container from each multilayer dose (128, 158). 107). A multilayer dose, comprising a body (136) including a principal material (124) surrounding a secondary material (125), the secondary material (125) having an annular edge zone (127) adjacent to a first end (129) of the body (136) and a dome-shaped zone (126) adjacent to a second end (130) of the body (136), wherein the distance (R) between the annular edge zone (127) and the first end (129) is comprised between 5% and 50% of the distance (L) between the first end (129) and the second end (130).

108). The multilayer dose of claim 107, wherein the secondary material (125) forms a tubular body (131) adjacent to the dome-shaped zone (126) and delimited by the annular edge zone (127). 109). The multilayer dose of claim 108, wherein the tubular body (131) extends about an axis (H) of the multilayer dose (128).

110). The multilayer dose of claim 109, wherein the tubular body (131) has a variable distance from the axis (H).

111). The multilayer dose of claim 109 or 110 wherein on passing from the dome-shaped zone (126) to the annular edge zone (127) the tubular body

(131) progressively broadens.

112). The multilayer dose of one of claims from 109 to 111, wherein the tubular body (131) has a variable thickness along the axis (H).

113). The multilayer dose of one of claims from 107 to 112, wherein the body

(136) is substantially cylindrical.

114). The multilayer dose of one of claims from 107 to 112, wherein the body

(136) is substantially prismatic.

115). The multilayer dose of one of claims from 107 to 114, wherein the principal material (124) is selected from a group comprising: polyethylenetherephthalate (PET), polypropylene (PP), polyvinylchloride

(PVC), polyethylene (PE), polyethylene naphthalate (PEN), polystyrene (PS) or lactic polyacid (PLA).

116). The multilayer dose of one of claims from 107 to 115, wherein the secondary material (125) is selected from a group comprising: a plastic material provided with a barrier property to oxygen, a plastic material provided with a barrier property to smells, a plastic material provided with a barrier property to moisture, a plastic material provided with a barrier property to light, a recycled plastic material, nano-compounds, a material of a same type as the principal material (124) with added colorant substances.

117). The multilayer dose of one of claims from 107 to 116, and further comprising a third material interposed between the principal material (124) and the secondary material (125) in order to facilitate adhesion between the principal material (124) and the secondary material (125).

118). A multilayer dose comprising a body (146, 166, 176) including a principal material (124) and a secondary material (125), characterised in that the secondary material (125) forms at least a first quantity (133, 153, 159,

189, 199, 209) and a second quantity (143, 154, 160, 190, 200, 210) that are at least partially embedded into the principal material (124), the first quantity

(133, 153, 159, 189, 199, 209) and the second quantity (143, 154, 160, 190,

200, 210) being separated from one another.

119). The multilayer dose of claim 118, wherein the body has a longitudinal axis (H).

120). The multilayer dose of claim 119, wherein the first quantity (133, 153,

159, 189, 199) and the second quantity (143, 154, 160, 190, 200) are arranged in sequence along the longitudinal axis (H).

121). The multilayer dose of claim 119, wherein the first quantity (189) and the second quantity (190) are arranged at two opposite sides of the longitudinal axis (H).

122). The multilayer dose of one of claims from 118 to 121, wherein the first quantity is shaped as a first concave portion (133, 153, 159, 189, 199, 209).

123). The multilayer dose of claim 122, wherein the second quantity is shaped as a second concave portion (143, 154, 160, 190, 200, 210).

124). The multilayer dose of claim 123, wherein the second concave portion

(154) is at least partially received internally of a concavity defined in the first concave portion (153).

125). The multilayer dose of one of claims from 118 to 122, wherein the second quantity (160) is shaped as a tubular body. 126). The multilayer dose of claim 125, when depending on claim 119, wherein the tubular body is divergent along the longitudinal axis (H).

127). The multilayer dose of claim 125, wherein the tubular body is substantially cylindrical. .

128). The multilayer dose of claim 125, wherein the tubular body is substantially prismatic.

129). The multilayer dose of one of claims from 118 to 128, wherein the first quantity (159) has an annular edge zone arranged on a first end surface (161) of the body (166).

130). The multilayer dose of claim 129, wherein the second quantity (160) has a further annular edge zone present on a second end surface (162) of the body (166), the second end surface (162) being opposite the first end surface

(161).

131). The multilayer dose of one of claims from 118 to 121, wherein the first quantity and the second quantity have a substantially spherical shape.

132). The multilayer dose of one of claims from 118 to 121, wherein the first quantity and the second quantity have a drop shape.

133). The multilayer dose of one of claims from 118 to 132, wherein the body (176) comprises a third quantity (155, 211) of the secondary material

(125), the third quantity (155, 211) being separated from the first quantity

(153, 209) and from the second quantity (154, 210).

134). The multilayer dose of claim 133, wherein the third quantity is shaped as a third concave portion (155, 211).

135). The multilayer dose of claim 133 or 134, when claim 133 depends on claim 119, wherein the first quantity (153), the second quantity (154) and the third quantity (155) are arranged in sequence along the longitudinal axis (H). 136). The multilayer dose of one of claims from 133 to 135, wherein the third quantity (155) is at least partially received internally of a concavity defined in the second quantity (154).

137). The multilayer dose of claim 133 or 134, when claim 133 depends on claim 119, wherein the first quantity (209) is arranged along the longitudinal axis (H), the second quantity (210) and the third quantity (211) being arranged at two opposite sides of the longitudinal axis (H) at a different height with respect to the first quantity (208).

138). The multilayer dose of one of claims from 118 to 137, wherein the body

(146, 166, 176) is substantially cylindrical.

139). The multilayer dose of one of claims from 118 to 137, wherein the body

(146, 166, 176) is substantially prismatic.

140). The multilayer dose of one of claims from 118 to 139, wherein the principal material (124) is selected from a group comprising: polyethylenetherephthalate (PET), polypropylene (PP), polyvinylchloride

141). The multilayer dose of one of claims from 118 to 140, wherein the secondary material (125) is selected from a group comprising: a plastic material provided with a barrier property to oxygen, a plastic material provided with a barrier property to smells, a plastic material provided with a barrier property to moisture, a plastic material provided with a barrier property to light, a recycled plastic material, nano-compounds, a material of a same type as the principal material (124) with added colorant substances.

142). The multilayer dose of one of claims from 118 to 141, and further comprising a third material interposed between the principal material (124) and the secondary material (125) in order to facilitate adhesion between the principal material (124) and the secondary material (125).

143). A method comprising stages of: extruding a principal material (124); supplying, in the principal material (124), discrete portions (123) of a secondary material (125), such as to obtain a multi-layer structure (152); severing multilayer doses (158) from the multilayer structure (152), characterised in that the stage of severing comprises cutting the discrete portions (123) in order to generate from each discrete portion (123) two quantities of secondary material (125) included in two consecutive doses

(158).

144). The method of claim 143, wherein the discrete portions (123) are severed from the multilayer structure (152) by cutting the multilayer structure

(152) along cutting lines (151) which are substantially perpendicular to a principal direction (G) in which the multilayer structure (152) extends.

145). The method of claim 143 or 144, wherein each discrete portion (123) comprises a dome-shaped zone (126) adjacent to a tubular body (131).

146). The method of claim 145, wherein during the stage of severing the dome-shaped zone (126) is separated from the tubular body (131), such that the dome-shaped zone (126) forms the first quantity (159) and the tubular body (131) forms the second quantity (160).

147). The method of claim 145 or 146, wherein the tubular body (131) is divergent along a longitudinal axis of the multilayer dose (158).

148). The method of claim 145 or 146, wherein the tubular body is substantially cylindrical.

149). The method of claim 145 or 146, wherein the tubular body is substantially prismatic. 150). The method of one of claims from 143 to 149, and further comprising a stage of compression-moulding the multilayer doses (158) such as to obtain cables (165).

151). The method of claim 150, wherein the hollow objects are preforms (165) for containers.

152). The method of claim 151, when claim 150 depends on one of claims from 145 to 149, wherein during the compression-moulding stage the dome- shaped zone (126) is sunk into an end wall (174) of a corresponding preform (165).

153). The method of claim 152, or of claim 153 when claim 150 depends on one of claims from 145 to 149, wherein, during the compression-moulding stage, the tubular body (131) is sunk into a lateral wall (175) of the preform (165).

154). The multilayer dose of one of claims from 143 to 153, wherein the principal material (124) is selected from a group comprising: polyethylenetherephthalate (PET), polypropylene (PP), polyvinylchloride (PVC), polyethylene (PE), polyethylene naphthalate (PEN), polystyrene (PS) or lactic polyacid (PLA).

155). The multilayer dose of one of claims from 143 to 154, wherein the secondary material (125) is selected from a group comprising: a plastic material provided with a barrier property to oxygen, a plastic material provided with a barrier property to smells, a plastic material provided with a barrier property to moisture, a plastic material provided with a barrier property to light, a recycled plastic material, nano-compounds, a material of a same type as the principal material (124) with added colorant substances. 156). The multilayer dose of one of claims from 143 to 155, wherien eachmultilayer dose (158) comprises a third material interposed between the principal material (124) and the secondary material (125) in order to facilitate adhesion between the principal material (124) and the secondary material

(125).

157). A multilayer dose comprising a body including a principal material

(125) and a secondary material (125), characterised in that a third material

(221) is interposed between the principal material (124) and the secondary material (125).

158). The multilayer dose of claim 157, wherein the third material (221) is destined to facilitate adhesion between the principal material (124) and the secondary material (125).

159). The multilayer dose of claim 157 or 158, wherein the secondary material (125) forms a mass (219) arranged internally of the principal material (124), the mass (219) having a lateral superficial zone (229) and two end surfaces (230, 231).

160). The multilayer dose of claim 159, wherein the third material (221) surrounds the lateral superficial zone (229).

161). The multilayer zone of claim 159 or 160, wherein the third material

(221) is in contact with the end surfaces (230, 231).

162). The multilayer dose of one of claims from 157 to 161, wherein the principal material (124) is selected from a group comprising: polyethylenetherephthalate (PET), polypropylene (PP), polyvinylchloride

163). The multilayer dose of one of claims from 157 to 162, wherein the secondary material (125) is selected from a group comprising: a plastic material provided with a barrier property to oxygen, a plastic material provided with a barrier property to smells, a plastic material provided with a barrier property to moisture, a plastic material provided with a barrier property to light, a recycled plastic material, nano-compounds, a material of a same type as the principal material (124) with added colorant substances.

164). A method comprising stages of: severing multilayer doses (8, 18, 28, 38, 48, 258, 402) from a multilayer structure (2, 32, 409) of a plastic material exiting a coextruder device (3, 33) in an outlet direction (X); reciprocally moving first forming means (10, 40) and second forming means

(12, 42) in a moulding direction (Y), such as to obtain a multilayer object (13,

43, 223) from each multilayer dose (8, 18, 28, 38, 48, 258, 402) by compression-moulding; characterised in that the moulding direction (Y) is transversal with respect to the outlet direction (X).

165). The method of claim 164, wherein the moulding direction (Y) is substantially perpendicular to the outlet direction (X).

166). The method of claim 164 or 165, wherein the outlet direction (X) is substantially horizontal.

167). The method of one of claims from 164 to 166, wherein the moulding direction (Y) is substantially vertical.

168). The method of one of claims from 164 to 167, wherein the multilayer dose (8, 18, 28, 258, 402) has a dimension, measured parallel to the moulding direction (Y) which is smaller than dimensions of the multilayer dose (8, 18,

28, 258, 402) measured transversally of the moulding direction (Y).

169). The method of one of claims from 164 to 168, wherein the multilayer structure (2, 409) is sheet-shaped and extends along the outlet direction (X).

170). The method of claim 168 or 169, wherein the multilayer object (13,

223) is selected from a group comprising: a cap for a container, a seal, a container having a small axial dimension, a container neck element (410), a disc element (300, 330) arranged internally of a cap (313, 333) for a container.

171). The method of one of claims from 164 to 167, wherein the multilayer dose (38, 48) extends mainly in a parallel direction to the moulding direction

(Y)-

172). The method of claim 171, wherein the multilayer object (43) is selected from a group comprising: a preform for a container, a container having a relevant axial dimension.

173). The method of one of claims from 164 to 172, wherein the multilayer dose (8, 18, 28, 38, 48, 258, 402) is of a substantially prismatic shape. 174). The method of cone of claims from 164 to 173, wherein the multilayer structure (2, 32, 409) comprises a principal material (4) which at least partially envelops a secondary material (5).

175). The multilayer dose of claim 174, wherein the principal material (4) is selected from a group comprising: polyethylenetherephthalate (PET), polypropylene (PP), polyvinylchloride (PVC), polyethylene (PE), polyethylene naphthalate (PEN), polystyrene (PS) or lactic polyacid (PLA). 176). The multilayer dose of claim 174 or 175, wherein the secondary material (5) is selected from a group comprising: a plastic material provided with a barrier property to oxygen, a plastic material provided with a barrier property to smells, a plastic material provided with a barrier property to moisture, a plastic material provided with a barrier property to light, a recycled plastic material, nano-compounds, a material of a same type as the principal material (4) with added colorant substances. 177). The method of one of claims from 174 to 176, wherein within the multilayer dose (8, 18, 28, 38, 48, 258, 402) the secondary material (5) has a substantially prismatic shape.

178). The method of one of claims from 174 to 177, wherein the secondary material (5) is arranged in a lower portion of the multilayer dose (38, 48).

179). The method of one of claims from 174 to 178, wherein within the multilayer dose (8, 38) the secondary material (5) is completely enveloped internally of the principal material (4).

180). The method of one of claims from 174 to 178, wherein the multilayer dose (18, 48, 258) has two external surfaces (17, 34) on which the secondary material (5) is present.

181). The method of one of claims from 174 to 178, wherein the multilayer dose (28) has four external surfaces (26) on which the secondary material (5) is present.

182). The method of one of claims from 174 to 181, wherein the multilayer dose has two distinct layers of secondary material (5) interposed between layers of principal material (4).

183). The method of one of claims from 174 to 182, wherein the multilayer dose comprises a third material interposed between the principal material (4) and the secondary material (5) for facilitating adhesion between the principal material (4) and the secondary material (5).

184). The method of one of claims from 174 to 183, wherein the multilayer object is a cap (223) having an end wall (14) and a lateral wall (15), a seal member (224) projecting from the end wall (14) inwardly of the lateral wall

(15), the secondary material (5) extending into the seal member (224).

185). The method of claim 184, wherein the seal member (224) is annular. 186). The method of claim 184 or 185, wherein the secondary material (5) forms and interlayer (227) which folds internally of the seal member (224).

187). The method of claim 184 or 185, wherein the secondary material (5) forms two interlayers (207) which fold internally of the seal member (224).

188). The method of one of claims from 174 to 187, wherein the multilayer object (13, 43, 223) comprises a region having means for removably fixing, the region being without the secondary material (5).

189). The method of one of claims from 164 to 188, wherein after the stage of severing, the multilayer doses (8, 18, 28, 38, 48, 258, 402) are conveyed towards the first forming means (10, 40) and the second forming means 812,

42).

190). The method of one of claims from 164 to 189, and further comprising the stage of modelling the multilayer structure (2, 32, 409) in order to stretch and orientate the molecules of the plastic material.

191). The method of one of claims from 164 to 189, and further comprising stages of modelling the multilayer doses (8, 18, 28, 38, 48, 258, 402) in order to stretch and orientate the molecules of the plastic material.

192). The method of claim 190 or 191, wherein the stage of modelling is done by pairs of rollers (52) rotating with progressively increasing speeds such as to thin out the plastic material.

193). The method of claim 192, wherein the rollers of the pairs of rollers (52) are rotatable about respective axes which are substantially perpendicular to the outlet direction (X).

194). The method of one of claims from 164 to 193, wherein the first forming means comprise a female moulding element (10, 40) cooperating with a male moulding element (12, 42) of the second forming means (12, 42).

195). An apparatus comprising: a coextruder device (3, 33) for dispensing a multilayer structure (2, 32, 409) of plastic material in an outlet direction (X); severing means for severing multilayer doses (8, 18, 28, 38, 48, 258, 402) from the multilayer structure (2, 32, 409) ; first forming means (10, 40) and second forming means (12, 42) which are reciprocally mobile in a moulding direction (Y), such as to obtain a multilayer object (13, 43, 223) from each multilayer dose (8, 18, 28, 38, 48, 258, 402) , by compression moulding; characterised in that the moulding direction (Y) is transversal of the outlet direction (X).

196). The apparatus of claim 195, wherein the moulding direction (Y) is substantially perpendicular to the outlet direction (X).

197). The apparatus of claim 195 or 196, wherein the outlet direction (X) is substantially horizontal.

198). The apparatus of one of claims from 195 to 197, wherein the moulding direction (Y) is substantially vertical.

199). The apparatus of one of claims from 195 to 198, wherein the coextruder device (3, 33) has an outlet opening (6, 7) from which exits the multilayer structure (2, 409), the outlet opening (6, 7) being delimited by two dimensions, one of which is larger than another thereof, such that the multilayer structure (2) is sheet-shaped, extending along the outlet direction

(X).

200). The apparatus of one of claims from 195 to 198, wherein the extrusion device has a main conduit (36) and a secondary conduit (37) for extruding respectively a principal material (4) and a secondary material (5), the secondary conduit (37) opening into the principal conduit (36) in a position such that the secondary material (5) is arranged in a lower portion of the multilayer dose (38, 48).

201). The apparatus of one of claims from 195 to 200 and further comprising a cutting device for severing the multilayer doses (8, 18, 28, 38, 48, 258, 402) from the multilayer structure (2, 409).

202). The apparatus of claim 201, wherein the cutting device comprises a single cutting element which is rotatable about an axis.

203). The apparatus of claim 201, wherein the cutting device comprises a plurality of cutting elements which are mobile along a looped path.

204). The apparatus of one of claims from 195 to 203, and further comprising a transferring device for conveying the multilayer doses (8, 18, 28, 38, 48,

258, 402) towards the first forming means (10, 40) and the second forming means (12, 42).

205). The apparatus of claim 204, wherein the transferring device comprises transferring means which are mobile along a looped path.

206). The apparatus of one of claims from 194 to 205, wherein the first forming means comprise a female moulding element (10, 40) cooperating with a male moulding element (12, 42) of the second forming means (12, 42).

207). The apparatus of one of claims from 194 to 206, wherein the first forming means (10, 40) and the second forming means (12, 42) are included in a mould (9, 39) for moulding a multilayer object (13, 43, 223), the apparatus comprising a plurality of moulds (9, 39) mounted on a moulding carousel.

208). The apparatus of claim 207, wherein the moulding carousel is rotatable about a vertical rotation axis.

209). The apparatus of one of claims from 194 to 208, wherein the first moulding means (10, 40) and the second moulding means 812, 42) are conformed such as to compression-mould a multilayer object selected from a group comprising: a cap (13, 223), a preform (43), a seal, a container, a container neck element (410).

210). The apparatus of one of claims from 194 to 209, further comprising a modelling device (51) acting on the plastic material for stretching and orientating the molecules of the plastic material.

211). The apparatus of claim 210, wherein the modelling device (51) comprises a plurality of pairs of rollers (52) which rotate about respective rotation axes at progressively increasing velocities, such as to thin out the plastic material.

212). The apparatus of claims 210 or 211, wherein the modelling device (51) is positioned immediately downstream of the coextruder device (3, 33), such as to act on the multilayer structure (2, 32, 409) before the multilayer doses

(8, 18, 28, 38, 48, 258, 402) are severed from the multilayer structure (2, 32,

409).

213). The apparatus of claim 210 or 211, when claim 210 depends on one of the claims from 201 to 203, wherein the modelling device 51 is arranged downstream of the cutting device, such as to act on the multilayer doses (8,

18, 28, 38, 48, 258, 402) which have already been severed from the multilayer structure (2, 32, 409).

214). A method comprising a stage of compression-moulding a multilayer dose (98) in a forming chamber, the dose (98) comprising a principal material

(94) and a secondary material (95), characterised in that during the moulding the principal material (94) flows into the forming chamber more rapidly than the secondary material (95), such as to surround the secondary material (95) in order to obtain an object (23) in which the secondary material (95) is embedded in the principal material (94). 215). The method of claim 214, wherein the object is a cap (23) for a container.

216). The method of claim 215, wherein the forming chamber comprises a portion in which a transversal wall (24) of the cap (23) is formed, and a further portion in which a skirt (25) of the cap (23) is formed, the principal material (94) flowing from the portion towards the further portion more rapidly than the second material (95), such that the skirt (25) is substantially without the secondary material (95).

217). The method of one of claims from 214 to 216, wherein the dose (98) has a substantially cylindrical shape.

218). The method of one of claims from 214 to 216, wherein the dose (98) has a substantially prismatic shape.

219). The method of one of claims from 214 to 218, wherein the layer (97) has a tubular conformation, the principal material (94) being arranged internally and externally of the layer (97).

220). The method of one of claims from 214 to 219, wherein the layer (97) is flat.

221). The method of claim 220, wherein the secondary material (95) forms a further layer arranged symmetrically to the layer (97) with respect to the axis

(H).

222). The multilayer dose of claims from 214 to 221, wherein the principal material (94) is selected from a group comprising: polyethylenetherephthalate

223). The multilayer dose of claims from 214 to 221, wherein the secondary material (95) is selected from a group comprising: a plastic material provided with a barrier property to oxygen, a plastic material provided with a barrier property to smells, a plastic material provided with a barrier property to moisture, a plastic material provided with a barrier property to light, a recycled plastic material, nano-compounds, a material of a same type as the principal material (94) with added colorant substances.

224). The method of one of claims from 214 to 223, wherein the dose (98) comprises a third material interposed between the principal material (94) and the secondary material (95) in order to facilitate adhesion between the principal material (94) and the secondary material (95).

225). A compression-moulded object, comprising a body formed from a first material and a second material, characterised in that the second material is a compound material.

226). The object of claim 225, having a preform geometry.

227). The object of claim 225, having a cap geometry.

228). The object of claim 225, having a container geometry.

229). The object of claims from 225 to 228, wherein the second material is a nano-compound material.

230). The object of one of claims from 225 to 228, wherein the material is a material obtained using Layer Multiplier System technology.

231). A preform having a body entirely formed by a material obtained using

Layer Multiplier System technology.

232). The preform of claim 231, obtained by compression moulding.

233). A method comprising a stage of compression-forming of a multilayer dose (402) of a plastic material in order to obtain a part of a container (411) provided with a container neck element (410).

234). The method of claim 233, and further comprising stages of dispensing a multilayer structure (409) of plastic material in an outlet direction through a plasticiser device (401), severing the multilayer dose (402) from the multilayer structure (409), supplying the multilayer dose (402) to compression-mould means (408), the stage of compression-forming comprising moving first forming means of the compression-mould means

(408) towards second forming means of the compression-mould means (408) in a moulding direction which is arranged transversally with respect to the outlet direction.

235). The method of claim 233 or 234, wherein the container neck element

(410) comprises a threaded portion (412).

236). The method of one of claims from 233 to 235, wherein the part of container comprises a dome-shaped segment (411) provided with a connecting zone (413) destined to be fixed to a container body and from which the container neck element departs (410).

237). The method of one of claims from 233 to 236, wherein the multilayer device (402) comprises at least a layer (405) of material having barrier properties to gas and/or light.

238). The method of one of claims from 233 to 237, wherein the multilayer dose (402) is conformed as a laminar element.

239). The method of claim 238, wherein the laminar element identifies a plate arranged transversally with respect to the moulding direction.

240). A method comprising stages of: dispensing, through a coextruder device, a structure comprising at least a principal material (304) and a secondary material (305) arranged in a predetermined number of layers; introducing into a cap (313, 333) a dose (308, 328) which is severed from the structure, the dose (308, 328) having a number of layers which is equal to a number of layers of the structure exiting the coextruder device; obtaining a disc element (300, 330) adhering to an end wall (314, 334) of the cap (313, 333) by compression-moulding the dose (308, 328) internally of the cap (313, 333).

241). The method of claim 240, wherein the dose (308, 328) is shaped internally of the cap (313, 333) by a punch element (302), the cap (313, 333) and the punch element (302) being mobile with respect to one another in a moulding direction, the moulding direction being transversal with respect to an outlet direction in which the structure exits the coextruder device.

242). The method of claim 240 or 241, wherein the dose (308, 328) is introduced into the cap (313, 333) in a position in which a longitudinal axis of the dose (308, 328) extends parallel to the end wall (314, 334).

243). The method of one of claims from 240 to 242, wherein the secondary material (305) forms a tubular layer in the dose (308), the principal material

(304) being arranged both internally and externally of the tubular layer.

244). The method of one of claims from 240 to 242, wherein the secondary material (305) forms a solid body (326) in the dose (328), the principal material (304) being arranged externally of the solid body (326).

245). The method of one of claims from 240 to 244, wherein the dose (308,

328) comprises a third material (306) interposed between the principal material (304) and the secondary material (305) in order to facilitate adhesion between the principal material (304) and the secondary material (305).

246). The method of one of claims from 240 to 245, wherein the disc element

(300) is surrounded by a seal lip (324) which projects from the end wall (314.

334).

247). The method of one of claims from 240 to 245, wherein the disc element

(330) comprises a seal element (329) which projects from a substantially flat central region of the disc element (330). 248). The method of one of claims from 240 to 247, wherein the disc element

(300, 330) comprises at least an internal layer (319, 320) of the secondary material (305), the at least an internal layer (319, 320) being interposed between two external layers (316, 318) of the principal material (304), the external layers (316, 318) having a same composition.

249). The method of claim 248, wherein the secondary material (305) forms two internal layers (319, 320) in the disc element (300), an intermediate layer

(321) of the principal material (304) being interposed between the two internal layers (319, 320).

250). The method of claim 249, wherein the two internal layers (319, 320) have a same composition.

251). The method of claim 249 or 250, wherein the two internal layers (319,

320) are joined to one another in a peripheral region (323) of the disc element

(300, 330).

252). The method of one of claims from 240 to 251, wherein the at least an internal layer (319, 320) is completely sunk into the principal material (304).

253). The method of one of claims from 240 to 252, wherein the disc element

(300, 330) has a distribution of layers of the principal material (304) and the secondary material (305) with is substantially symmetrical with respect to a parallel plane to the end wall (314, 334).

254). The method of one of claims from 240 to 253, wherein the secondary material has barrier properties to gas.

255). A cap, comprising an end wall (314, 334), a lateral wall (315) which projects from the end wall (314, 334) and a disc element (300, 330) adhering to the end wall (314, 334), the disc element (300, 330) having at least an internal layer (319, 320) interposed between two external layers (36, 318), characterised in that the external layers (316, 318) have the same composition.

256). The cap of claim 255, wherein the external layers (316, 318) are formed from a principal material (304) and the at least an internal layer (319, 320) is formed from a functional secondary material (305).

257). The cap of claim 256, wherein the secondary material (305) has gas barrier properties.

258). The cap of claim 256 or 257, wherein the secondary material (305) forms two internal layers (319, 320) in the disc element (300), an intermediate layer (321) of the principal material (304) being interposed between the two internal layers (319, 320).

259). The cap of claim 258, wherein the two internal layers (319, 320) have a same composition.

260). The cap of claim 258 or 259, wherein the two internal layers (319, 320) are joined to one another in a peripheral region (323) of the disc element

(300, 330).

261). The cap of one of claims from 256 to 260, wherein the at least an internal layer (319, 320) is completely embedded in the principal material

(304).

262). The cap of one of claims from 256 to 261, wherein the disc element

(300, 330) has a distribution of layers of the principal material (304) and of the second material (305) which is substantially symmetrical with respect to a plane which is parallel to the end wall (314, 334).

263). The cap of one of claims from 256 to 262, wherein a third material

(306) is interposed between the principal material (304) and the secondary material (305), which third material (306) is for improving adhesion between the principal material (304) and the secondary material (305). 264). The cap of one of claims from 255 to 263, wherein the disc element

(300) is surrounded by a seal lip (324) which projects from the end wall (314,

334).

265). The method of one of claims from 255 to 263, wherein the disc element

(330) comprises a seal element (329) which projects from a substantially flat central region of the disc element (330).