WO2018002899A1

WO2018002899A1 - Adhesive valve for containers for foodstuffs

Info

Publication number: WO2018002899A1
Application number: PCT/IB2017/053967
Authority: WO
Inventors: Valerio Binda
Original assignee: Masterpack S.P.A.
Priority date: 2016-06-30
Filing date: 2017-06-30
Publication date: 2018-01-04
Also published as: ITUA20164789A1

Abstract

Adhesive valve that comprises a flexible label (1) having at least one lower surface (la) provided with adhesive, wherein a flexible membrane (2) is applied to the bottom surface (la) of the flexible label (1) and has a lower surface (2a) substantially not adhesive, wherein the flexible label (1) is shaped so that at least one portion (2b) of the upper surface of the flexible membrane (2) is not covered by the flexible label (1). The present description also relates to a sheet of plastic material and a container for foodstuffs comprising said adhesive valve.

Description

25 JULY 2017

SIB BW785M-TE

ADHESIVE VALVE FOR CONTAINERS FOR FOODSTUFFS

TECHNICAL FIELD This present description relates to an adhesive valve, in particular an adhesive and flexible valve which can be applied on openings made in hermetic containers, for example for foods to be heated, in order to release gases that develop in them. The present description also relates to a sheet of plastic material and a container for foodstuffs comprising said adhesive valve.

BACKGROUND OF THE DESCRIPTION

European Patent 2275252 describes an adhesive valve that comprises a flexible label having at least one lower surface provided with adhesive, wherein a flexible membrane is applied to the bottom surface of the flexible label, is completely covered by the flexible label and has a lower surface) substantially not adhesive. To act as a gas discharge valve, one or more cuts are made in the flexible label astride the geometric projection of the perimeter of the flexible membrane. In this known adhesive valve, the discharge gas flow rate is greatly influenced by the type of adhesive used to fix the valve to the container, so if the adhesive is too strong it is difficult for the label to rise at the cuts, while if it is too weak there is a risk that the valve will not properly perform its closing function.

To address this technical problem, WO 2015/111015 Al discloses a similar adhesive valve in which the flexible membrane is always covered completely by the flexible label but is provided with cuts intersecting with cuts made in the flexible label.

However, the adhesive valves known from such publications do not perfectly work, since they have a release of gas greater or less than expected according to the size and shape of the flexible label and the flexible membrane, when they are pulled or folded, in particular due to the swelling or bending of the sheet on which they are applied. SIB - 2 - BW785M-TE

SUMMARY OF THE DESCRIPTION

The objection of the present description is therefore to provide an adhesive valve free from such drawbacks. Said object is achieved with an adhesive valve whose main features are specified in the first claim, while other features are specified in the remaining claims.

Thanks to the particular portion of the flexible membrane not covered by the flexible label, the functionality of the adhesive valve according to the present description is less affected by the effects caused by its deformation, for example by tractions or flexions, as the gases pass outside not through cuts but through at least one slot which is formed between said uncovered portion of the flexible membrane and the outer surface of the container when the internal pressure is greater than the external one and which is closed in a substantially hermetic manner when the external pressure is greater than or equal to the internal one.

Furthermore, thanks to the particular sizes and shapes of the flexible label, the flexible membrane and/or the uncovered portion of the flexible membrane, the effects of any deformation of the adhesive valve on its functionality are further limited.

BRIEF DESCRIPTION OF THE DRAWINGS

Further advantages and features of the adhesive valve according to this description will become apparent to the skilled in the art from the following detailed and non- limiting description of one embodiment thereof with reference to the accompanying drawings in which:

- Figure 1 shows a top view of the adhesive valve on a support;

- Figure 2 shows a bottom view of the adhesive valve of Figure 1 without the support;

- Figure 3 shows a top view of the adhesive valve of Figure 1 applied on a container surface. SIB BW785M-TE

EXPLANATORY EMBODIMENTS

Referring to Figures 1 and 2, it is seen that the adhesive valve according to the present description includes in a known manner a flexible label 1 having at least one lower surface la provided with adhesive. At least one flexible membrane 2 is applied under the lower surface la of the flexible label 1 and in turn has a substantially non- adhesive bottom surface 2a, namely that is not provided with adhesive or in any case is substantially less adherent than the lower surface la of the flexible label 1 provided with adhesive. The flexible membrane 2 is preferably formed by punching a support 3 of the same material, in sheet or strip, which has an extension larger than the flexible label 1 and on which one or more flexible labels 1 of the same type are disposed on at least one row. The flexible label or labels 1 can also be obtained by punching a larger sheet or strip having a surface provided with adhesive, in which the excess portion, namely the one not comprising the label or labels 1, is removed after application of the same on the support 3.

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

The flexible membrane 2 may also comprise paper having a thickness comprised between 20 and 500 microns. The lower surface 2a of the flexible membrane 2 is preferably treated with a material preferably compatible with a food use, which is suitable to make it non-adherent or partially adherent, particularly silicone or vaseline oil.

The adhesive layer applied on the lower surface la of the flexible label 1 may be a common acrylic adhesive based on water or with UV crosslinking or acrylic with an organic solvent, or a silicone-based adhesive for high temperatures (up to 250 °C).

Further characteristics of the materials and the manufacturing process of the SIB BW785M-TE flexible label 1 and the flexible membrane 2 are described in European patent 2275252 and in WO 2015/111015 Al .

According to the present description, the flexible label 1 is shaped such that at least one portion 2b of the upper surface of the flexible membrane 2 is not covered by the flexible label 1. In particular, at least one portion of the perimeter of the flexible label 1 passes over the flexible membrane 2 so that this portion of the perimeter divides the flexible membrane 2 into the portion 2b not covered by the flexible label 1 and at least one portion 2c covered by the flexible label 1 (and delimited by a dotted line in Figure 1) . The surface area of the flexible membrane 2 covered by the flexible label 1 is preferably greater than the area of the surface of the flexible membrane 2 not covered by the flexible label 1. The flexible label 1 has a substantially polygonal and/or curvilinear shape, for example square with rounded corners. The flexible membrane 2 has a substantially polygonal and/or curvilinear shape, for example elliptical. The perimeter of the flexible label 1 preferably has at least one concave portion lb that starts from an outer edge lc of the flexible label 1 and extends inwardly of the flexible label 1. The concave portion lb preferably comprises the perimeter portion of the flexible label 1 passing over the flexible membrane 2. The concave portion lb preferably has an elongated shape, in particular essentially triangular with rounded corners, that is, like a tongue. At least two segments of the concave portion lb cross the perimeter of the flexible membrane 2 and form between them an angle a comprised between 0° and 90°, in particular between 0° and 30°. One or more cuts 4 start inward from an edge of the flexible label 1, so as to act as tamper indications of the label itself.

Referring to Figure 3, it is seen that the bottom surface of the flexible label 1 can be joined to a surface 5 thanks to the adhesive disposed between these surfaces. The surface 5 may belong to a sheet suitable for closing a food container, for example a sheet of plastic material that can be used to make a bag or be welded to the edge of a rigid tub. The surface 5 comprises at least one opening 6 covered by the flexible membrane 2 of the adhesive valve, so that any gas generated within said container passes through the opening 6 and the gap between the flexible membrane 2 and the surface 5, in the direction indicated by the arrows.

Any variants or additions may be made by the skilled person to the embodiment SIB - 5 - BW785M-TE herein described and illustrated while remaining within the scope of the following claims. In particular, further embodiments may include the technical characteristics of one of the following claims by adding one or more technical features described in the text or illustrated in the drawings, taken individually or in any mutual combination.

Claims

SIB - 6 - BW785M-TE CLAIMS

1. Adhesive valve that comprises a flexible label (1) having at least one lower surface (la) provided with adhesive, wherein a flexible membrane (2) is applied to the bottom surface (la) of the flexible label (1) and has a lower surface (2a) substantially not adhesive, characterized in that the flexible label (1) is shaped so that at least one portion (2b) of the upper surface of the flexible membrane (2) is not covered by the flexible label (1).

2. Adhesive valve according to claim 1, characterized in that at least one portion of the perimeter of the flexible label (1) passes over the flexible membrane (2), so that this portion of the perimeter divides the flexible membrane (2) into the portion (2b) not covered by the flexible label (1) and into at least one portion (2c) covered by the flexible label (1).

3. Adhesive valve according to claim 1 or 2, characterized in that the perimeter of the flexible label (1) has a least one concave portion (lb) which starts from an outer edge (lc) of the flexible label (1) and extends towards the inside of the flexible label (1).

4. Adhesive valve according to claim 3, characterized in that the concave portion (lb) comprises the portion of the perimeter of the flexible label (1) which passes over the flexible membrane (2).

5. Adhesive valve according to claim 3 or 4, characterized in that the concave portion (lb) has an elongated shape, in particular substantially triangular with rounded corners.

6. Adhesive valve according to one of claims 3 to 5, characterized in that at least two segments of concave portion (lb) intersect the perimeter of the flexible membrane (2) and form between them an angle (a) between 0° and 90°, in particular between 0° and 30°.

7. Adhesive valve according to one of claims 1 to 6, characterized in that the area of the surface of the flexible membrane (2) covered by the flexible label (1) is greater than the area of the surface of the flexible membrane (2) not covered by the flexible label (1). SIB - 7 - BW785M-TE

8. Adhesive valve according to one of claims 1 to 7, characterized in that one or more cuts (4) start from an edge of the flexible label (1) towards the inside.

9. Sheet of plastic material (5) comprising at least one opening (6) for release of gas, characterized in that it comprises at least one adhesive valve according to one of claims 1 to 8, wherein the flexible membrane (2) of the adhesive valve covers this opening (6).

10. Container for foodstuffs comprising at least one surface provided with at least one opening for release of gas, characterized in that at least one adhesive valve according to one of claims 1 to 8 is applied on said surface, wherein the flexible membrane (2) of the valve adhesive covers this opening.