Method and multi-layer element for making objects by compression

Abstract

A method for making products (P), wherein it comprises the steps of: preparing a multi-layer element (1) comprising a non-extrudable material (2) at least 80% in the solid phase and at least one layer (2) which is a barrier to liquids and / or to oxygen; housing the multi-layer element (1) in a mould (100), between a female portion (101) defining a forming cavity (102), and a punch (103) movable along a first longitudinal axis (X); compressing the multi-layer element (1) by shifting the punch (103) towards a bottom wall (102a) of the cavity (102); and moving at least one lateral sector (104) of the female portion (101) defining the forming cavity (102) towards said punch (103); the step of moving the lateral sector (104) being carried out to compress the multi-layer element (1) between the sector (104) itself and the punch (103).

Description

[0001] DESCRIPTION

[0002] Method and multi-layer element for making objects by compression moulding

[0003] This invention relates to a method for making various types of products, by compression moulding a multi-layer element. This invention also relates to a multi-layer element suitable for compression moulding for making objects.

[0004] As is known, regulations linked to environmental protection are increasingly directed towards the use of natural and compostable materials, usually materials which are vegetable fibre- or bacterial substance-based. Such materials are used to make objects such as in particular containers for food and drinks, capsules for coffee, caps or bottles.

[0005] Natural fibre-based materials are formed by means of specific methods, typically by compression moulding.

[0006] Indeed, vegetable fibre- or bacteria-based materials such as for example cellulose, cannot be subjected to forming by extrusion techniques in which it is necessary to heat the material to very high temperatures. In this case, the excessive heating of the cellulose material would burn the fibres, damaging the material itself.

[0007] For this reason, the cellulose is prepared in “dose” form and compressed inside a mould to obtain the required shape. If necessary the dose may be heated to facilitate shaping by compression, controlling the temperature at values much lower than the known extrusion techniques.

[0008] The dose of cellulose may also be in the form of a piece obtained by cutting a continuous web and appropriately fed to the moulding apparatuses.

[0009] The doses may preferably be created separately, advantageously eliminating processing scrap / waste.

[0010] Alternatively, the cellulose material may be fed in the form of a continuous film, through the relative compression moulding stations. However, the nature of the vegetable fibre-based material means that said production technique is limited only to some objects.

[0011] Indeed it should be noticed that cellulose is known to be hydrophilic and therefore, if making an object intended to be in contact with water and moisture, it has to be coupled to a film which is a barrier to water (hydrophobic materials).

[0012] However, the element obtained in this way in multi-layer form, although capable of providing a barrier both to oxygen and to water, has major limits in the relative moulding steps.

[0013] Indeed, moulding involves a step of compressing the dose between a male portion (punch) which is inserted in a female portion defining a forming compartment. That compressing step applies a drawing action on the dose which stretches the fibres until the desired final shape is reached. In this context it should be noticed that, especially for very deep articles, the barrier films coupled to the cellulose material may be excessively stretched and torn.

[0014] It should also be considered that in order to obtain a compostable dose, the hydrophobic barrier films, for example, made of thermoplastic polymers are used in quantities / thicknesses which are very limited compared with the thickness of the cellulose.

[0015] Therefore, whilst the cellulose is more shapable and stretchable in the compressing step partly due to the greater quantity of material usable in the individual dose, the barrier film is thinner and therefore fragile and easily damageable.

[0016] For this reason, compostable doses provided with film which is a barrier to water have major limits in the steps of compression moulding to make particularly deep articles.

[0017] It should also be noticed that the use of a barrier film with a greater thickness and therefore capable of better withstanding the stretching steps would compromise the biodegradability features of the finished product, as well as increasing the production costs of the product itself. Therefore, the aim of the invention is to provide a multi-layer element and a method for making objects by compression moulding which are free of the above-mentioned disadvantages.

[0018] In particular, a first aim of this invention is to provide a multi-layer element for making objects by compression moulding which is compostable and at the same time efficient in its functions as a barrier to oxygen, to water, to steam, to aromas, or to fats.

[0019] Even more particularly, one aim of this invention is to provide a multi-layer element which is versatile, inexpensive, usable in many areas in which a barrier to oxygen and to water is required and at the same time suitable for making products by compression moulding which necessitates stretching of the materials of which the element is composed for a large depth value. A further aim of this invention is to provide a method for making various types of products which is capable of compression moulding multi-layer elements.

[0020] In particular, a further aim of the invention is to provide a compression moulding method capable of preserving the integrity of the materials of which the multi-layer element is composed, in particular in the element stretching and drawing steps.

[0021] In a first aspect of the invention, a multi-layer element for making objects by compression moulding is provided, wherein it comprises a non- extrudable material at least 80% in the solid phase and at least one layer which is a barrier to liquids and / or to oxygen.

[0022] Advantageously, the non-extrudable material is natural fibre-based, in particular cellulose-based.

[0023] Even more preferably, the non-extrudable material is a web of airlaid whose thickness is greater than that of the barrier layer.

[0024] According to a further aspect of the invention, the barrier layer is positioned on at least one outer surface of the non-extrudable material and / or inside that material. The barrier layer is preferably made of thermoplastic film with a thickness which is much less than the thickness of the non-extrudable material.

[0025] According to a further aspect of this invention a method for making products is provided, wherein it comprises the steps of: preparing a multilayer element of the type described above, housing the multi-layer element in a mould, between a female portion defining a forming cavity, and a punch movable along a first longitudinal axis; compressing the multi-layer element by shifting the punch towards a bottom wall of the cavity; and moving at least one lateral sector of the female portion defining the forming cavity towards said punch.

[0026] Advantageously, the step of moving the lateral sector is carried out to compress the multi-layer element between the sector itself and the punch and defines a narrowing of the width of said forming cavity measured along a line perpendicular to said longitudinal axis of the punch.

[0027] Preferably, a plurality of lateral sectors opposite each other are moved towards the punch.

[0028] The compressing step allows the layers which did not adhere in the preceding coupling steps to be made to adhere perfectly.

[0029] That step of compressing the multi-layer element by shifting the punch is carried out before the step of moving at least one lateral sector towards the punch.

[0030] Advantageously, the lateral sectors narrow the width of the forming compartment in a controlled way and simultaneously with the compressing action of the punch, so as to not excessively stretch the multi-layer element along the punch forward movement line. The invention can be better understood and implemented with reference to the accompanying drawings, which illustrate several example, non-limiting embodiments of it, in which:

[0031] - Figures 1 to 3 schematically show the sequence of the method for compression moulding a multi-layer element; - Figures 4 to 6 schematically show a second embodiment of the sequence of the method for compression moulding a multi-layer element;

[0032] - Figures 7 and 8 schematically show two different types of multi-layer element in the respective initial steps of compression moulding; and

[0033] - Figures 9 to 12 schematically show different embodiments of a multilayer element for compression moulding which are all within the scope of this invention.

[0034] With reference to Figures 9 to 12 what is illustrated is a multi-layer element 1 for compression moulding according to this invention and according to different embodiments.

[0035] In particular, the multi-layer element 1 comprises a non-extrudable material 2 at least 80% in the solid phase and at least one barrier layer 3 which is a barrier to liquids and / or to oxygen.

[0036] In particular, the non-extrudable material 2 is natural fibre-based, preferably but without limiting the scope of the invention, it is cellulose- based.

[0037] Advantageously, the material 2 is a web of airlaid whose thickness is greater than that of the barrier layer 3.

[0038] Alternatively, the material 2 may be in the form of doses obtained from pre-compacted powdered cellulose.

[0039] Moreover, the material 2 may have a constant cross-section and density or there may be specific zones with variable thickness and / or density, depending on the products which must be formed by compression moulding and their use.

[0040] By way of example, the appended figures schematically illustrate a multilayer element 1 in which the material 2 has a constant cross-section.

[0041] Advantageously, as illustrated in Figures 9, 11 and 12 the barrier layer 3 is positioned on at least one outer surface of the non-extrudable material 2.

[0042] In this case, the barrier layer 3 is usually hydrophobic so as to protect the cellulose material 2 from contact with water and moisture.

[0043] For that purpose, as is specifically illustrated in Figure 12, the barrier layer 3 may advantageously be positioned on two opposite outer surfaces of the non-extrudable material 2.

[0044] According to a further embodiment illustrated in Figure 10, the barrier layer 3 is positioned inside the non-extrudable material 2.

[0045] The barrier layer 3 may be in the form of a film coupled to the non- extrudable material 2, or it may be in the form of a liquid sprayed or spread directly on the non-extrudable material 2.

[0046] For example, the barrier layer 3 may comprise EVOH, PVOH, PA, or fibrebased materials such as for example nano-cellulose or thin metal layers.

[0047] The layer 3 fed in liquid form is solidified before and / or after and / or during forming by compression.

[0048] However, it should be specified that the barrier layer 3 may have any nature and composition depending on the specific functionalities of the product obtained by compression moulding the multi-layer element 1 .

[0049] Moreover, the multi-layer element 1 may also comprise a covering layer 4 coupled on the barrier layer 3. In this case, as illustrated in Figures 11 and 12, the barrier layer 3 is located between the non-extrudable material 2 and the covering layer 4.

[0050] Preferably, the covering layer 4 is made in the form of natural fibre-based film.

[0051] Advantageously, the covering layer 4 is a very thin paper suitable for covering one or both of the outer surfaces of the multi-layer element 1 .

[0052] As specified above, the multi-layer element 1 described above is suitable for making product by means of a compression moulding method.

[0053] The method comprises the initial step of preparing the multi-layer element 1 described above and in accordance with the various embodiments referred to above and shown in Figures 9 to 12.

[0054] The multi-layer element 1 is then housed in a mould 100, between a female portion 101 defining a forming cavity 102 and a punch 103 movable along a first longitudinal axis “X”.

[0055] That step of preparing the multi-layer element 1 comprises the step of feeding a continuous web made of the non-extrudable material 2 and coupling the continuous web to the barrier layer 3 which is a barrier to liquids and / or to oxygen.

[0056] In a first embodiment, the barrier layer 3 is coupled to the web of non- extrudable material 2 by positioning a barrier film on at least one respective outer surface of the web itself.

[0057] That step may be carried out on a single surface or on the two opposite surfaces of the non-extrudable material 2, as illustrated in Figure 12.

[0058] The coupling may be carried out with known methods such as compression and / or by using binding substances.

[0059] Alternatively, in accordance with the embodiment in Figure 10, the step of coupling the barrier layer 3 to the web of non-extrudable material 2 may be carried out by positioning the barrier film inside the web. In this embodiment, the barrier layer 3 is “embedded” in the non-extrudable material 2.

[0060] Moreover, in this case, the film of the barrier layer 3 may be located between two webs of non-extrudable material 2.

[0061] Alternatively, the web of non-extrudable material 2 may be formed by compacting loose material (for example powdered cellulose). In this case, the compacting is carried out around the barrier layer 3 so as to incorporate the layer 3 itself inside the non-extrudable material 2.

[0062] In accordance with a further embodiment, the barrier layer 3 may be sprayed or spread in substantially liquid form on at least one outer surface of the web of non-extrudable material 2.

[0063] In this case too, that step may be carried out on a single surface or on the two opposite surfaces of the non-extrudable material 2, as illustrated in Figure 12.

[0064] In accordance with the embodiments of Figures 11 and 12, the method may also comprise, after the step of coupling the barrier layer 3 to the web of non-extrudable material 2, the step of coupling at least one covering layer 4 on the barrier layer 3. In this case too, the step of coupling the covering layer 4 may be carried out by means of known compression techniques and / or by using binding substances.

[0065] Moreover, as illustrated in Figure 12, there may be two covering layers 4 respectively positioned at the opposite outer surfaces of the web of non- extrudable material 2.

[0066] Advantageously, the covering layer 4 may be in the form of a very thin paper which is positioned on the barrier layer 3 continuously during feeding of the web of non-extrudable material 2.

[0067] Advantageously, the material 2 may be fed in the form of separate pieces and the various layers may be separate, fed in the form of small disks and superposed on the material 2.

[0068] According to a first embodiment of the invention, the multi-layer element 1 formed in this way is housed in the mould 100 in the form of a piece in sheet form.

[0069] In this case, the multi-layer element 1 is cut from a multi-layer continuous web into individual doses with shape and dimensions suitable for forming a respective product “P”.

[0070] Alternatively, the multi-layer element 1 is housed in the mould 100 in the form of a continuous web. In this case, the multi-layer continuous web may be compression moulded by a set of moulds 100 to simultaneously obtain a plurality of products “P”.

[0071] The method according to this invention also comprises the step of compressing the multi-layer element 1 by shifting the punch 103 towards a bottom wall 102a of the cavity 102.

[0072] It should be noticed that the outer surface of the punch 103 and the inner surface of the cavity 102 defines the shape of the product “P” to be made by compression. By way of example, the figures schematically illustrate a cup-shaped product “P”, that is to say, obtained by means of a particularly deep drawing action. That product “P” may be for example a bottle cap or a capsule for coffee. However, the parts of the mould 100 may have any shape depending on the production requirements of the product “P”.

[0073] After the compressing step, the step of moving at least one lateral sector 104 of the female portion 101 defining the forming cavity 102 towards the punch 103 is carried out.

[0074] That step is carried out to compress the multi-layer element 1 between the sector 104 itself and the punch 103.

[0075] Advantageously, there is a plurality of lateral sectors 104 opposite each other and defining the lateral wall 104a of the forming cavity 102.

[0076] More in detail, the movable lateral sectors 104 define at least a predominant lateral portion of the forming cavity 102. In other words, the lateral sectors 104 establish a predominant lateral development dimension of the cavity 102, meaning one that is greater than half when measured along the longitudinal axis "X".

[0077] In this context, the bottom wall 102a may feature a depression forming a "step" (not shown in the figures), which constitutes a lower end of the lateral wall 104a. In this case, the mentioned end of the lateral wall 104a is fixed, as it is defined by the bottom wall 102a. It should nevertheless be specified that this end of the lateral wall defined in the bottom wall 102a, when measured along the "X" axis, has a significantly smaller extent compared to the extent of the lateral wall 104a formed by the movable sectors 104.

[0078] The sectors 104 are movable towards the punch 103.

[0079] It should be noticed that the movement of the sectors 104 towards the punch 103 defines a narrowing of the width of the forming cavity 102 measured along a line perpendicular to the afore-mentioned longitudinal axis “X” of the punch 103.

[0080] There may also be further sectors which are telescopic relative to the punch and fed towards the cavity. Such telescopic sectors, in combination with the movement of the lateral sectors 104 facilitate the forming and prevent breakage (tearing) of one or more layers. As specified above, the movement of the punch 103 towards the bottom wall 102a is started before the start of the step of moving the lateral sectors 104.

[0081] Advantageously, the movement of the sectors 104 starts when the punch 103 has already started to compress the multi-layer element 1 inside the cavity 102 (Figure 2) but has not yet completed that compression. In other words, the movement of the lateral sectors 104 takes place during the movement of the punch towards the bottom wall 102a.

[0082] In this situation, the final compressing movement by the punch 103 and by the lateral sectors 104 takes place substantially in a coordinated way, so as to form the element 1 by simultaneously compressing the whole surface of the multi-layer element 1 itself.

[0083] In this way the element 1 is not stretched towards the bottom wall 102a but is instead “received” inside the cavity which is gradually narrowed to compress both the bottom wall 102a zone and the lateral surface 104a zone.

[0084] In this regard, it should be noted that the cavity 102 is, for most of its extension along the "X" axis, defined by the movable sectors 104. Consequently, any depressions formed in the bottom wall 102a, which thus determine a fixed-end lateral section, do not affect the stretching action of the fibers that constitute the multilayer element.

[0085] In this case, the stretching action is instead controlled by the movement of the movable sectors 104, which accommodate the element 1 within the cavity.

[0086] That movement preserves the structure of the materials of which the multilayer element 1 is composed and in particular the thin films which define the barrier layer 3 and the covering layer 4.

[0087] With reference to the embodiment of Figures 4 to 6, the method may also comprise a step of locking the perimetric edge of the multi-layer element 1 before moving the punch 103 along the line “X”.

[0088] That step is carried out by moving a gripping body 105, positioned around the punch 103, towards a contact plane 101 a of the female portion 101 positioned around the forming chamber 102.

[0089] It should be noticed in particular that the contact plane 101 a is made on the upper surface of each lateral sector 104 on which the multi-layer element 1 is rested in the respective initial step of housing on the press 100.

[0090] The gripping body 105 is therefore moved towards the contact plane 101a so as to engage with and retain the perimetric edge of the multi-layer element 1 during the compressing step by the punch 103 and the individual lateral sectors 104 (Figures 5 and 6).

[0091] Advantageously, the multi-layer element is retained in position during the respective forming steps, securing the respective perimetric edge a predetermined distance from the bottom wall 102a.

[0092] It should be specified that Figures 1 to 6 illustrate a process of forming by compression moulding of a multi-layer element 1 in which the barrier layer 3 is housed inside the non-extrudable material 2 (Figure 10).

[0093] However, as already specified, the method described above is implementable with any type of multi-layer element 1 described above. For example, Figure 7 and 8 illustrate the mould 100 in the initial step of moulding a multi-layer element 1 respectively provided with a barrier layer 3 and with a covering layer 4 on one and on two opposite surfaces of the non-extrudable material 2.

[0094] This invention solves the problems encountered in the prior art and brings important advantages.

[0095] First, the multi-layer element 1 is completely compostable and / or recyclable and at the same time capable of providing a barrier to oxygen and to water. Therefore it is possible to use the element 1 to make products “P” which are highly versatile in terms of their use.

[0096] Moreover, it is possible to use a barrier layer 3 in the form of a very thin film which therefore guarantees the barrier function without affecting the biodegradability features of the whole element 1 . That advantage is derived from the method according to the invention which does not stretch the fibres in the respective compression moulding step.

[0097] Indeed, the punch 103 and the lateral sectors 104 work in synergy to simultaneously compress the element 1 along two perpendicular lines.

[0098] Therefore, while the central zone of the element 1 is compressed between the punch 103 and the bottom wall 102a, the peripheral zone of the element 1 is gradually compressed towards the punch by the lateral sectors 104. That action shapes the element 1 gradually and without stretching the materials of the element 1 itself, therefore avoiding breakage and excessive lengthening of the barrier layer 3.

[0099] It is advantageously possible to use elements 1 with layers of materials having limited thicknesses, with the consequent advantages in terms of quantities of materials used and therefore production costs.

[0100] It should also be noticed that the absence of excessive heating of the element 1 , whilst heating in any case may be provided at very low temperatures compared with extrusion methods, allows the integrity of the materials to be preserved during the compressing action in any case facilitating forming of the product “P”.

[0101] Advantageously, it is possible to obtain products “P” which are very deep, however without affecting the structural integrity of the materials of which the multi-layer element 1 is composed.

Claims

CLAIMS1.

1. A multi-layer element (1 ) for making objects by compression moulding, wherein it comprises a non-extrudable material (2) at least 80% in the solid phase and at least one layer (2) which is a barrier to liquids and / or to oxygen, said non-extrudable material (2) is a web or segment of airlaid whose thickness is greater than that of the barrier layer (3).

2. The multi-layer element according to the preceding claim, wherein said non-extrudable material (2) is natural fibre-based.

3. The multi-layer element according to any one of the claims, wherein said non-extrudable material (2) is cellulose-based.

4. The multi-layer element according to any one of the preceding claims, wherein said barrier layer (3) is positioned on at least one outer surface of said non-extrudable material (2).

5. The multi-layer element according to any one of the preceding claims, wherein said barrier layer (3) is positioned on two opposite outer surfaces of said non-extrudable material (2).

6. The multi-layer element according to any one of claims 1 to 3, wherein said barrier layer (3) is positioned inside said non-extrudable material (2).

7. The multi-layer element according to any one of the preceding claims, wherein said barrier layer (3) is in the form of film coupled to the non- extrudable material (2).

8. The multi-layer element according to any one of claims 1 to 6, wherein said barrier layer (3) is in liquid form, sprayed or spread on the non- extrudable material (2).

9. The multi-layer element according to claim 4 or 5, wherein it also comprises a covering layer (4) coupled on the barrier layer (3); said barrier layer (3) being located between the non-extrudable material (2) and the covering layer (4).

10. The multi-layer element according to the preceding claim, wherein said covering layer (4) is made in the form of natural fibre-based film.11 . A method for making products (P), wherein it comprises the steps of:- preparing a multi-layer element (1 ) according to any one of claims 1 to 11 ;- housing the multi-layer element (1 ) in a mould (100), between a female portion (101 ) defining a forming cavity (102), and a punch (103) movable along a first longitudinal axis (X);- compressing the multi-layer element (1 ) by shifting the punch (103) and the cavity (102a) relative to each other so as to move the punch (103) itself towards a bottom wall (102a) of the cavity (102); and- moving at least one lateral sector (104) of the female portion (101 ) defining at least a predominant lateral portion of the forming cavity (102) towards said punch (103);- said step of moving the lateral sector (104) being carried out to compress the multi-layer element (1 ) between the sector (104) itself and the punch (103).

12. The method according to the preceding claim, wherein said step of moving at least one lateral sector (104) defining the narrowing of the width of said forming cavity (102) measured along a line perpendicular to said longitudinal axis (X) of the punch (103).

13. The method according to either claim 11 or 12, wherein said step of moving at least one lateral sector (104) is carried out by moving a plurality of lateral sectors (104) which are opposite each other towards the punch (103).

14. The method according to any one of claims 11 to 13, wherein said step of compressing the multi-layer element (1 ) by shifting the punch (103) is carried out before the step of moving at least one lateral sector (104) towards the punch (103).

15. The method according to the preceding claim, wherein said step of moving at least one lateral sector (104) towards the punch (103) is carried out during the movement of the punch (103) towards the bottom wall (102a).

16. The method according to any one of claims 11 to 15, wherein it also comprises a step of locking the perimetric edge of the multi-layer element (1 ), before the step of compressing the multi-layer element (1 ) by shifting the punch (103) towards the bottom wall (102a).

17. The method according to the preceding claim, wherein said step of locking the perimetric edge is carried out by moving a gripping body (105) positioned around the punch (103) towards a contact plane (101 a) of the female portion (101 ) positioned around the forming chamber (102); said perimetric edge of the multi-layer element (1 ) being retained during the forming step carried out by the punch (103) and by the lateral sector (104).

18. The method according to any one of claims 11 to 17, wherein said multi-layer element (1) is housed in the mould in the form of a piece in sheet form.

19. The method according to any one of claims 11 to 17, wherein said multi-layer element (1 ) is housed in the mould in the form of a continuous web.

20. The method according to either claim 18 or 19, wherein said step of preparing the multi-layer element (1 ) comprises, before the step of housing the element (1 ) in the mould (100), the step of feeding a continuous web made of the non-extrudable material (2) and coupling said continuous web to said barrier layer (3) which is a barrier to liquids and / or to oxygen.

21. The method according to the preceding claim, wherein said step of coupling the barrier layer (3) to the web of non-extrudable material (2) is carried out by positioning a barrier film on at least one respective outer surface of the web.

22. The method according to claim 20, wherein said step of coupling the barrier layer (3) to the web of non-extrudable material (2) is carried out by positioning a barrier film inside the web.

23. The method according to claim 20, wherein said step of coupling the barrier layer (3) to the web of non-extrudable material (2) is carried out by spraying or spreading a substantially liquid barrier on at least one outersurface of the web.

24. The method according to claim 20, wherein said step of preparing the multi-layer element (1 ) also comprises, after the step of coupling the barrier layer (3) to the continuous web, the step of coupling at least one covering layer (4) on the barrier layer.

25. The method according to any of claims 11 to 24, wherein said lateral sectors (104) define a lateral development dimension of the cavity (102), measured along the longitudinal axis (X), that is greater than half of the cavity (102) itself as measured along said axis (X).

Images