WO2019150252A1

WO2019150252A1 - Filter for food containers and process for its manufacture

Info

Publication number: WO2019150252A1
Application number: PCT/IB2019/050705
Authority: WO
Inventors: Valerio Binda
Original assignee: Masterpack S.P.A.
Priority date: 2018-01-31
Filing date: 2019-01-29
Publication date: 2019-08-08
Also published as: IT201800002276A1

Abstract

Filter which comprises at least one flexible label (1) having two surfaces connected to each other by at least one incision (3), wherein at least one (1) of these two surfaces is provided with adhesive, the flexible label (1) comprising at least one filtering layer (5) permeable to fluids and suitable to retain particulate or powders, wherein at least one flexible membrane (2) having two surfaces connected to each other by at least one incision (4) is joined to the surface (1a) provided with adhesive of the flexible label (1). The present description also relates to a sheet and a container for foods comprising said filter, as well as a process for its manufacture.

Description

Filter for food containers and process for its manufacture

TECHNICAL FIELD

The present description relates to a filter, in particular an adhesive and flexible filter which can be applied onto openings formed in sheets of hermetic containers, for example for food to be heated, to release gases which develop therein. The present description also relates to a sheet and a food container comprising said filter, as well as a process for its manufacture.

FRAMEWORK OF THE DESCRIPTION

European patent 2275252 describes an adhesive valve which comprises a flexible label having at least one lower surface provided with adhesive, wherein a flexible membrane is applied to the lower surface of the flexible label, is completely covered by the flexible label and has a lower surface substantially non-adhesive. To act as a gas relief valve, one or more cuts are made in the flexible label straddling the geometric projection of the perimeter of the flexible membrane.

Publication WO 2015/111015 Al describes a similar adhesive valve, in which the flexible membrane is always completely covered by the flexible label but is provided with cuts which intersect with cuts made in the flexible label.

Said known adhesive valves, however, have a not entirely optimal functioning, i.e. a gas release greater or less than expected according to the size and shape of the flexible label and the flexible membrane, if the openings are partially occluded by particles of material contained in the container and pushed towards them by the gases released by the valve.

Moreover, known filters for releasing gas from food containers are not provided with valves to prevent the passage of gas in the absence of pressure differences but instead comprise a rigid frame which maintains a net and is welded around an opening formed in the container.

Said known filters are relatively cumbersome, as well as difficult and expensive to manufacture, mainly due to the rigid frame and the welding to the container.

US 2006/030472 Al, DE 3312887 Al and FR 2353451 Al describe filters provided with a flexible adhesive label, in some cases with a flexible membrane which has substantially the same extension as the flexible label, as in DE 3312887 Al, which corresponds to the preamble of claim 1. In these known filters, also the flexible membrane must be provided with adhesive for being applied on a food container, with consequent increase in manufacturing costs and complexity, especially if it is desired to produce a sheet or a ribbon comprising a plurality of filters. The sealing of the gas seal around said known filters is also limited due to the relatively small extent of the flexible label, so that a sealing fluid is spread between the flexible label and the flexible membrane. Said fluid may cause food contaminations.

SUMMARY OF THE DESCRIPTION

The object of the present description is therefore to provide a filter free from such drawbacks. Said object is achieved with a filter, a sheet, a container and a process whose main features are specified in the attached claims.

Thanks to the particular filtering layer associated with a flexible label, the filter according to the present description can be manufactured and applied onto containers in an easy and economical manner.

Being equipped with a flexible membrane, the filter can also function as a valve to control the flow of fluids in a complete manner, namely by allowing, limiting or preventing the passage of fluids according to any differences in pressure, or in a partial manner, namely by controlling the passage of fluids, depending on the shape, size and arrangement of the incisions in the flexible label and in the flexible membrane.

Moreover, thanks to the particular dimensions and shapes of the flexible label and/or the flexible membrane and/or the filtering layer, the effects of the possible deformation of the filter on its functionality are further limited.

Thanks to the particular manufacturing process, a series of filters can be produced quickly and efficiently. BRIEF DESCRIPTION OF THE DRAWINGS

Further advantages and characteristics of the filter, the sheet, the container and the process according to the present description will be clear to those skilled in the art from the following detailed and non-limiting description of some embodiments thereof with reference to the attached drawings wherein:

Figure 1 shows a bottom view of a first embodiment of the filter;

Figure 2 shows a top view of the filter of Figure 1;

Figure 3 shows the enlarged section III-III of Figure 2;

Figure 4 shows a bottom view of a second embodiment of the filter;

Figure 5 shows a top view of the filter of Figure 4;

Figure 6 shows the enlarged section VI- VI of Figure 5;

Figure 7 shows a bottom view of a third embodiment of the filter;

Figure 8 shows a top view of the filter of Figure 7;

Figure 9 shows the enlarged section IX-IX of Figure 8;

Figure 10 shows a bottom view of a fourth embodiment of the filter;

Figure 11 shows a top view of the filter of Figure 10;

Figure 12 shows the enlarged section XII-XII of Figure 11;

Figure 13 shows the filter of Figure 12 during use;

Figure 14 shows a scheme of the manufacturing process of the first embodiment of the filter.

EXEMPLARY EMBODIMENTS

With reference to Figures 1 to 3, it is seen that the filter according to the first embodiment of the description comprises a flexible label 1 having at least one lower surface la provided with adhesive. A flexible membrane 2 can be applied below the lower surface la of the flexible label 1. The flexible membrane 2 can be obtained by punching a support of the same material, in sheet or strip, which has a larger extension than the flexible label 1 and on which one or more flexible labels 1 of the same type are applied, arranged on at least one row. Also the flexible label or labels 1 can be obtained by punching a larger sheet or tape having a surface provided with adhesive, in which the exceeding part, i.e. the part not including the label or labels 1, is removed after their application on the support of the flexible membrane 2.

The flexible label 1 and the flexible membrane 2 can be obtained from a film of a plastic material suitable for coming into contact with food belonging in particular to the group consisting of polypropylene (for example between 35 and 60 microns thick), polyester (for example between 25 and 45 microns thick) or plastic materials with equivalent characteristics. The film of the flexible label 1 may be formed from a laminate comprising the same plastic materials, paper, aluminum and/or a polyamide film (for example between 10 and 20 microns thick), or a PE-Evoh-PE laminate.

The surface of the flexible membrane 2 facing the flexible label 1 may be treated with a material preferably compatible with a food use, which is suitable to make it non adherent or limitedly adherent, in particular silicone or vaseline oil, which is then dried, so that the flexible membrane 2 is dry and solid.

The adhesive layer applied to the lower surface la of the flexible label 1 may be a pressure-activated adhesive or PSA (Pressure Sensitive Adhesive), in particular an aqueous-based acrylic or UV cross-linking or acrylic adhesive with an organic solvent, or a silicone-based adhesive for high temperatures (up to 250 °C).

Further characteristics of the materials and of the manufacturing process of the flexible label 1 and of the flexible membrane 2 are described in European patent 2275252 and in publication WO 2015/111015 Al.

The flexible label 1 is provided with at least one first incision 3 suitable to connect the two surfaces of the flexible label 1. In particular, the incision 3 can be rectilinear or curvilinear or, as in the first embodiment, closed, so as to define at least one opening, for example one or more circular holes, in particular three circular holes 3 which pass through the flexible label 1. In an alternative embodiment, not shown in the figures, the incision in the flexible label may form a notch on the edge of the flexible label 1, so that a portion of the perimeter of the flexible label 1 passes over the flexible membrane 2 and this portion then divides the flexible membrane 2 into a portion not covered by the flexible label 1 and in at least one remaining portion covered by the flexible label 1. The flexible label 1 may have a substantially polygonal and/or curvilinear shape, for example circular as in the first embodiment or substantially square with rounded corners. The flexible label 1 preferably extends over an area x mm wide and y mm long, with x and y comprised between 25 and 45. For example, the flexible label 1 has a diameter of about 30 mm.

The flexible membrane 2 preferably has a substantially polygonal and/or curvilinear shape, for example substantially circular, and is provided with at least one second incision 4 suitable to connect the two surfaces of the flexible membrane 2.

In the present embodiment the incisions 3 in the flexible label 1 have substantially the same shape and the same dimensions of the incisions 4 in the flexible membrane 2 and are substantially aligned with these incisions 4. In other embodiments the incisions 3 in the flexible label may have substantially different dimensions, shapes and/or positions with respect to the incisions 4 in the flexible membrane 2.

The flexible label 1 and/or the flexible membrane 2 are joined to a filtering layer 5 made of a material which is permeable to fluids and is suitable to retain particulate or powders, such as a fine mesh, a fabric or a non- woven fabric. The thickness of the filtering layer 5 is preferably between 15 and 100 microns. The filtering layer 5 is arranged on at least one side of the flexible label 1 and covers at least partially, preferably completely, the first incision 3 or the second incision 4. A portion of the adhesive surface la of the flexible label 1 is free, i.e. it is not covered neither by the flexible membrane 2 nor by the filtering layer 5. Said free portion of the adhesive surface la of the flexible label 1 partially or preferably completely surrounds the flexible membrane 2 and/or the filtering layer 5.

The filtering layer 5 is preferably laminated with the flexible label 1 or the flexible membrane 2 by means of adhesive or heat-sealing. In other embodiments, both the flexible label 1 and the flexible membrane 2 can be laminated with one or more filtering layers, so as to obtain a filter with two or more filtering layers.

In the present embodiment, the filtering layer 5 is joined to the flexible membrane 2, so that the flexible membrane 2 is arranged between the flexible label 1 and the filtering layer 5. In other embodiments, a further filtering layer may be arranged between the flexible label 1 and the flexible membrane 2.

The filtering layer 5 has preferably and substantially the same perimeter of the flexible membrane 2, in particular being made from a single layer of filtering layer 5 with the flexible membrane 2, shaped for example by laser cutting or mechanical punching.

With reference to Figures 4 to 6, it is seen that the filter according to the second embodiment is similar to the first embodiment, with the difference that the flexible label 1 and the flexible membrane 2 have a substantially square shape with rounded edges and a cross-shaped incision 3, 4. The flexible label 1 has dimensions of approximately 40 mm x 40 mm.

With reference to Figures 7 to 9, it is seen that the filter according to the third embodiment is similar to the first embodiment, with the difference that the flexible label 1 and the flexible membrane 2 have series of incisions 3, 4 aligned with each other, and in the shape of a quarter circle, arranged concentrically. The flexible label 1 and the flexible membrane 2 have a substantially circular shape but are not concentric, as in the first and second embodiments. The flexible label 1 has a diameter of about 42 mm.

With reference to Figures 10 to 12, it is seen that the filter according to the fourth embodiment is similar to the second embodiment, with the difference that the incisions 3 in the flexible label 1, for example four substantially circular holes, do not have the same the shape of the incisions 4 in the flexible membrane 2 and/or are arranged in different positions with respect to them. Anyway, the incisions 3 in the flexible label 1 lead towards the flexible membrane 2 and the incisions 4 in the flexible membrane 2 lead towards the flexible label 1, so that the incisions 3, 4 in a rest (closed) position are closed at least partially by the flexible membrane 2 or the flexible label 1.

With reference to Figure 13, it is seen that a sheet 6 suitable for closing or forming a food container, for example a sheet of plastic material which can be used to make a bag or to be heat- sealed to the edges of a rigid tray, comprises at least one incision 6a which connects the two surfaces of the sheet 6 and which can be covered by the filter. The incision 6a in the sheet 6 may be rectilinear, curved or closed, so that the portion of the sheet 6 surrounded by the incision 6a can be removed and form an aperture, for example substantially circular. The lower surface la of the flexible label 1 can be joined to the upper surface of the sheet 6 thanks to the adhesive applied to the lower surface la, so that the flexible membrane 2 and the filtering layer 5 are arranged between the flexible label 1 and the sheet 6. In particular, the filtering layer 5 covers at least partially the incision

of the sheet 6 opposite to the filter. If in a container comprising the sheet 6 a pressure substantially greater than the pressure outside the container itself is generated, for example caused by cooking food in the container, the gases 7 under pressure in the container move the flexible label 1 away from the flexible membrane 2, thus creating a passage between the flexible label 1 and the flexible membrane 2, so that these gases 7 pass towards the outside of the container through the incision 6a of the sheet 6, the filtering layer 5, the incision 4 of the membrane flexible 2, the space between the flexible membrane 2 and the flexible label 1 and the incisions 3 of the flexible label 1. Any powders pushed by the gases 7 are retained in the container by the filtering layer 5. When the pressure in the container returns to be substantially equal to the external pressure, the flexible label 1 can again adhere to the flexible membrane 2, thus closing the passage of gases 7 between the sheet 6 and the flexible label 1, in particular thanks to the elasticity of the materials and to electrostatic forces and/or Van der Waals forces which occur between the flexible membrane 2 and the flexible label 1.

With reference to Figure 14, it is seen that in a first operating step of the manufacturing process of the first embodiment of the filter, a first layer 21 of the same material of the flexible label 1 described above is preferably wound on a first roller 22. The first layer 21 is pulled in the direction of the arrows towards one or more first auxiliary rollers 23 which apply on one side of the first layer 21 a layer of adhesive 24 taken from a first auxiliary roller 23 from a tank 25. The adhesive 24 in the tank 25 is the adhesive applied to the lower surface la of the flexible label 1. In alternative embodiments, the adhesive 24 may be applied to the first layer 21 before being wound onto the first roller 22 together with a detachable protective sheet, and/or with a rotogravure or flexographic process, with devices and methods similar to those used for rotogravure or flexographic printing.

The first layer 21 provided with adhesive 24 is then joined to a second layer 26, preferably wound on a second roller 27, by second auxiliary rollers 28, so as to obtain a laminated material 29 which can be wound on a third roller 30. The second layer 26 is in turn a laminated material comprising a layer of the same material of the above described flexible membrane 2 and/or a layer of the same material of the filtering layer 5 described above. Before being wound on the third roller 30, at least one mechanical or laser die cutting machine, in particular a roller die-cutter 31, forms a series of incisions in the first layer 21 and/or a series of incisions in the second layer 26, in successive steps or preferably simultaneously.

The incisions in the first layer 21 define in the first layer 21 a series of flexible labels 1 and/or first incisions 3 in the flexible labels 1, as described above. The incisions in the second layer 26 define in the second layer 26 a series of flexible membranes 2 and/or of filtering layers 5 and/or of second incisions 4 in the flexible membranes 2, as described above. In an alternative embodiment, the incisions 3, 4, when they are the same and aligned with each other, can be made in the first layer 21 and in the second layer 26 with a single action of the punching machine 31.

In alternative embodiments, the substrates forming the first layer 21 or the second layer 26 can be joined together immediately before or during the lamination performed by the second rollers 28.

The excess part of the first layer 21 which does not comprise the flexible labels 1 can be removed before the laminate 29 is wound on the third roller 30, while the excess part of the second layer 26 which does not comprise the flexible membranes 2 can act as a support for the flexible labels 1.

In a subsequent step, not shown in the figures, the laminated material 29 can be taken from the third roller 30 and cut to obtain one or more filters which can be applied on one or more openings 6a formed in a sheet 6 for food use, wherein the surface la provided with adhesive of the flexible label 1 adheres at least partially to a surface of the sheet 6.

Any variations or additions may be made by those skilled in the art to the embodiments described and illustrated herein while remaining within the scope of the following claims. In particular, further embodiments may include the technical characteristics of one of the following claims with the addition of one or more technical characteristics described in the text or illustrated in the drawings, taken singularly or in any mutual combination.

Claims

1. Filter which comprises at least one flexible label (1) having two surfaces connected to each other by at least one incision (3), wherein at least one (la) of these two surfaces is provided with adhesive, wherein the flexible label (1) comprises at least one filtering layer (5) permeable to fluids and suitable to retain particulate or powders, wherein at least one flexible membrane (2) having two surfaces connected to each other by at least one incision (4) is joined to the surface (la) provided with adhesive of the flexible label (1), wherein the flexible membrane (2) is arranged between the flexible label (1) and the filtering layer (5), wherein the filtering layer (5) covers at least partially the incision (4) of the flexible membrane (2), characterized in that a portion of the adhesive surface (la) of the flexible label (1) is not covered by the flexible membrane (2) or by the filtering layer (5), so that this portion surrounds partially or completely the flexible membrane (2) and the filtering layer (5).

2. Filter according to the previous claim, characterized in that the flexible membrane (2) is laminated with the filtering layer (5).

3. Filter according to one of the preceding claims, characterized in that the incisions (3) in the flexible label (1) have substantially the same shape and the same dimensions of the incisions (4) in the flexible membrane (2) and are substantially aligned with these incisions (4).

4. Filter according to claim 1 or 2, characterized in that the incisions (3) in the flexible label (1) have substantially different shapes, dimensions and/or positions with respect to the incisions (4) in the flexible membrane (2).

5. Filter according to one of the preceding claims, characterized in that the filtering layer (5) has substantially the same perimeter of the flexible membrane (2).

6. Filter according to one of the preceding claims, characterized in that the surface of the flexible membrane (2) facing the flexible label (1) is treated with a material that makes it non-adherent or limitedly adhering.

7. Filter according to one of the preceding claims, characterized in that the filtering layer (5) is a fine mesh, a fabric or a non-woven fabric.

8. Sheet (6) comprising two surfaces connected to each other by at least one incision (6a), characterized in that the surface (la) provided with adhesive of the flexible label (1) of a filter according to one of the previous claims adheres at least partially to one of the two surfaces of the sheet (6) and the filtering layer (5) of the filter covers at least partially the incision (6a) of the sheet (6).

9. Food container, characterized in that it comprises at least one sheet (6) according to the previous claim.

10. Process for manufacturing filters, comprising the following operating steps:

joining a first layer (21) to at least one second layer (26) by means of at least one adhesive layer (24) arranged between these layers (21, 26) so as to obtain a laminated material (29);

making incisions (3) in the first layer (21) so as to connect with at least one incision

(3) two surfaces of the first layer (21) and define in the first layer (21) at least one flexible label (1) having at least one surface (la) provided with adhesive (24); characterized in that the second layer (26) comprises at least one filtering layer (5) permeable to fluids and suitable to retain particulate or powders, wherein further incisions

(4) are made in the second layer (26) so as to connect with at least an incision (4) two surfaces of the second layer (26) and define in the second layer (26) at least one flexible membrane (2) joined to the surface (la) provided with adhesive (24) of the flexible label (1), wherein a portion of the surface (la) provided with adhesive (24) of the flexible label

(1) is not covered by the flexible membrane (2) or by the filtering layer (5), so that this portion partially or completely surrounds the membrane flexible (2) and the filtering layer

(5).