Valve and packaging

Abstract

FIELD: food packaging.SUBSTANCE: pressure relief valves for food packaging. The pressure relief valve comprises a cup-shaped main body (1) with a bottom (11) and a circumferential wall (12) for attachment to a flexible packaging material. The bottom has at least one through hole (14) forming a passage through the main body. There is a valve membrane adjacent to the main body on the packaging side in the area around the through hole(s) (14), with a sealing liquid between the main body and the valve membrane. The valve membrane closes at least one through hole (14). The circumferential wall (12) has, on its outer side, a multitude of recesses (71).EFFECT: creating a pressure relief valve, the shape of which ensures optimal efficiency and minimal impact on the environment.13 cl, 10 dwg

Description

[0001] The present invention relates to the field of pressure relief valves for food packaging.

[0002] Some food products, such as freshly roasted coffee beans or coffee powder, tend to degas over time. Therefore, food packaging, such as coffee bags, is equipped with a pressure relief valve. Pressure relief valves allow gases, such as carbon dioxide, to be released from the packaging while preventing ambient air from entering, preventing oxygen from entering the packaging and maintaining freshness.

[0003] Pressure relief valves generally have a cup-shaped main body, with the edge of the annular wall of the main body welded or glued to the inside of the packaging material. Both the bottom of the main body and the packaging have an opening. A disc in the form of a valve membrane is located at the bottom of the main body, with oil, such as silicone oil, acting as a sealing fluid between the bottom and the disc. If excess pressure is present inside the package, gas transferred through the opening in the bottom lifts the disc, allowing the gas to escape into the interior of the main body and then out of the package through the opening in the packaging. When there is no excess pressure inside the package, the disc, adjacent to the bottom of the main body, ensures a hermetic seal.

[0004] Pressure relief valves of this type are useful because they allow fresh products to be packaged directly for delivery to the end consumer without the need for any intermediate repackaging. This, in addition to ensuring freshness for the consumer, also has environmental benefits. However, pressure relief valves do increase their environmental impact.

[0005] Thus, the objective of the present invention is to overcome the shortcomings of prior art pressure relief valves. In particular, the objective of the present invention is to provide a pressure relief valve whose design ensures optimal efficiency and minimal environmental impact.

[0006] The present invention relates to a pressure relief valve, wherein the valve comprises a cup-shaped main body with a bottom and a circumferential wall, attached to a flexible packaging material. The bottom has at least one through hole, forming a passage through the main body. There is a valve membrane adjacent to the main body on the packaging side (in the cup formed by the main body) in the region around the through hole(s), with a sealing fluid between the main body and the valve membrane. According to an aspect of the present invention, the annular wall has a plurality of recesses on its outer side.

[0007] The bottom side opposite to the packaging side is called the “product side” in this text.

[0008] It was found that a relatively simple to implement measure of external recesses allows the amount of material required for a pressure relief valve to be reduced without compromising function or mechanical stability.

[0009] The recesses may, in particular, take the form of axially extending grooves with ribs between the grooves. The grooves may be evenly spaced around the periphery of the main body.

[0010] Rounded cylindrical parts with a ribbed outer structure are known in the art, such as beverage bottle caps or other rotating parts, since the ribbed structure improves grip and makes the corresponding part easier to rotate manually. However, the main bodies of pressure relief valves are designed to be attached to the housing rather than rotated. However, according to the content of the present invention, a structure with grooves and ribs or other recesses on the outer side of the circumferential wall of the main body is preferable in that it serves to improve mechanical stability at a certain volume of material—or, viewed from another perspective, to reduce the volume of material required to achieve a certain mechanical stability.

[0011] In particular, it was found that the structure of the recesses, in particular those in the form of axially extending grooves, works to strengthen the main body.

[0012] The general shape of the main body may be such that the outer surface corresponds to the surface of a substantially disc-shaped body, namely, cylindrical or slightly conical with a relatively small axial extension, with recesses on the outer surface and, possibly, an outwardly projecting flange. Thus, equipment designed for handling prior art pressure relief valves without recesses can be used to process the pressure relief valve, in particular for attaching it to the interior of the package. Thus, the solution according to the present invention does not require any additional investment in equipment.

[0013] The recesses can be arranged in a uniform distribution - with equal distances between adjacent recesses - around the periphery of the main body.

[0014] The number of recesses may, for example, be from 10 to 40, in particular from 15 to 30.

[0015] If the recesses are axially extending grooves, their shape in horizontal cross-section (a cross-section through a plane perpendicular to the axis) may be continuously curved-concave. Specifically, the recesses may be shallow, meaning that the central angle of the curved section is less than 180°, such as less than 120° or less than 90°.

[0016] In a group of embodiments, the annular wall of the main body has a section on the packaging side that is an outwardly protruding flange, in addition to a structured section that has recesses. The structured section can extend to the end of the main body on the product side.

[0017] In a group of embodiments, the packaging-side section is a portion with an outer surface that is smooth in the sense that it does not have any grooves or ribs. Also in this group, the structured section may optionally extend to the product-side end of the main body.

[0018] As an alternative to the structured section extending to the end of the main body on the product side, the outer surface of the annular wall of the main body may have an additional, third section, which is located on the product side of the structured section and which is again smooth, so that the recesses in this alternative embodiment are limited to the central (relative to the axial directions) portion of the outer surface of the annular wall.

[0019] The bottom of the main body is not affected by recesses in the circumferential wall. On the product side, the bottom of the main body may contain at least one oil groove for accommodating a reservoir containing sealing fluid.

[0020] In a group of embodiments, particularly if the valve has a permeable membrane, the bottom of the main body has at least one recess on the product side, forming a recessed section. At least one through hole—or at least one of the through holes—has an opening on the product side in the recessed section. Thus, the opening of the through hole(s) on the product side is offset relative to the outermost plane on the product side. This means that in the presence of a permeable membrane, the opening of the through hole(s) is offset relative to the plane of the permeable membrane. The recessed section can thus form a system of ventilation grooves with spacers between them.

[0021] In embodiments of the invention, the dividers have rounded edges. This reduces the risk of damage to the permeable membrane when the packaging is subjected to mechanical stress.

[0022] In embodiments, if the packaging is to contain a fine-grained product, such as coffee powder (ground coffee), the valve further comprises a permeable membrane attached to the bottom on the product side and covering at least one through-hole to prevent the product from clogging the through-hole, while being permeable to gases. The permeable membrane may be a fabric membrane. In this text, "fabric" is used to cover all types of flexible materials made of fibers or strands or interwoven threads, including non-woven materials, woven or knitted textiles, or other textile structures.

[0023] In some embodiments, the valve further comprises a retaining portion. The retaining portion is configured to be positioned on the packaging side of the valve diaphragm. It prevents the valve diaphragm from falling out of the main body even in situations where the valve is subjected to significant mechanical impact. The valve may be particularly susceptible to such impact during transportation and assembly processes when supplied in bulk. Under mechanical impact, the retaining portion holds the valve diaphragm in place, even if the adhesion of the sealing fluid may be insufficient. The retaining portion may be retained relative to the main body by a circumferential wall of the main body, which forms a recess so that the retaining portion can snap into place within the main body.

[0024] In embodiments, the valve may be biodegradable, that is, all components may be made of biodegradable material.

[0025] In this text, “biodegradable” may mean biologically degradable in accordance with the European standard EN 13432 (as of the end of 2021). Additionally, or alternatively, it may mean biodegradable in accordance with the European standard EN 14995 (as of the end of 2021). Thus, “biodegradable” refers, in particular, to “biodegradable” in accordance with EN 13432 and / or in accordance with EN 14995.

[0026] To the extent that water-soluble polymers are mentioned in this text, such water-soluble polymer can optionally be degraded in wastewater treatment plants (aerobic biodegradability) in accordance with DIN EN ISO 9888 (as of the end of 2021); determined in accordance with the so-called Zahn-Wellens test.

[0027] In particular, at least one component, such as the main body, of the valve may be made of a polymer composition comprising a water-soluble polymer. In embodiments of the invention, the polymer composition further comprises a salt, in particular a hygroscopic salt.

[0028] In addition to containing a water-soluble polymer and salt, the composition may contain a plasticizer. The plasticizer may be selected from the group consisting of polyols (oligo- and polyhydroxy compounds) and low molecular weight amides.

[0029] In embodiments of the invention, the main body and, if present, the permeable membrane and the fixing portion, are in each case a polymer composition that contains polyvinyl alcohol (PVOH) as a water-soluble polymer, a salt and glycerin as a plasticizer.

[0030] In embodiments of the invention, the valve membrane is a polymer composition that is insoluble in water but biodegradable, such as polyhydroxybutyrate (PHB).

[0031] In addition to the pressure relief valve, the invention also relates to packaging, in particular to a coffee bag for coffee beans or ground coffee. The packaging comprises a flexible, elastic packaging material, as well as a pressure relief valve, as described herein. The main body of the pressure relief valve is attached to the packaging material. In particular, the annular end surface of the pressure relief valve can be attached to the packaging material, wherein the valve membrane (and, if present, the locking portion) is located in the hollow space between the bottom of the main body and the packaging material. The packaging material is generally gas-tight, but has an opening or other permeable structure in a position enclosed by the circumferential wall of the main body.

[0032] Next, embodiments of the present invention are described with reference to the drawings. In the drawings, like numerals denote like or corresponding elements. The drawings show the following:

[0033] Fig. 1 - exploded view of the pressure relief valve;

[0034] Fig. 2 - view of the main body;

[0035] Fig. 3 - sectional view of the valve assembly;

[0036] Fig. 4 - another view of the main body;

[0037] Fig. 5 - another view of the main body;

[0038] Fig. 6 - another sectional view of the valve assembly;

[0039] Fig. 7 - alternative embodiment of the main body;

[0040] Fig. 8 - another alternative embodiment of the main body;

[0041] Fig. 9 is a schematic side view of another embodiment of the main body; and

[0042] Fig. 10 - schematic view of the valve in the package.

[0043] The pressure relief valve shown in Fig. 1, 3 and 6 comprises a main body 1, which is also shown in Fig. 2, 4 and 5. The main body 1 has, in general, the shape of a flat cup with a bottom 11 and a circumferential wall 12. The bottom 11 has a sealing surface and, opposite the sealing surface, a surface on the product side.

[0044] The circumferential wall 12 surrounds the sealing surface of the bottom 11. It has a substantially circular cylindrical or slightly conical outer surface, with axially extending grooves 71 arranged at regular intervals, and with ribs 72 between the grooves. The axially extending ribs 72 improve mechanical stability, even if the circumferential wall 12 is relatively thin, i.e., manufactured using a minimal amount of plastic material.

[0045] In this embodiment, the circumferential wall 12 additionally has a flange 13, i.e., an outwardly projecting cuff, at its end opposite the bottom 11, so that the annular end surface 16, which carries the energy-guiding rib 18 on the packaging side, is wider. The bottom has at least one through hole 14—in the illustrated embodiment, three through holes 14—which is closed by a valve membrane 2 adjacent to the bottom 11 on its sealing surface. Between the bottom 11 and the valve membrane 2, a thin layer of sealing liquid, in particular oil, such as silicone oil, is located.

[0046] In this text, the terms "circumferential" as well as "radial", "outer" or "inner" are given in relation to the axis 10 of the main body.

[0047] The main body 1, on the inner side of the circumferential wall 12 and in the plane defined by the valve membrane 2, has an expansion-accommodating groove 41 that can accommodate any expansion of the valve membrane so that the valve membrane does not bulge when expanding, for example, when absorbing a certain amount of moisture.

[0048] In embodiments, the pressure relief valve has a permeable membrane 3 in addition to the main body 1 and the valve membrane 2. The permeable membrane 3 may, for example, be a fabric, such as a non-woven fabric. The permeable membrane is attached to the bottom surface on the product side and covers at least the through hole(s) 14.

[0049] The main body has a plurality of oil grooves on the side portion of the sealing surface. Specifically, the main body has an inner oil groove 21 surrounding the opening, and further has a ring of three first outer oil grooves 22 and a ring of three second outer oil grooves 23, wherein the first outer oil grooves 23 are arranged around the second outer oil grooves 22.

[0050] The outer oil grooves serve as reservoirs for the sealing fluid. For this purpose, they are arranged radially so as to be covered by the valve diaphragm (see, for example, Fig. 3 or Fig. 6).

[0051] In some embodiments, the pressure relief valve, in addition to the main body 1 and the valve membrane 2, and, if applicable, the permeable membrane 2, has a retaining portion 4. The retaining portion 4 is optional and can serve as a spacer between the flexible packaging material and the valve membrane 2, preventing the valve membrane 2 from shifting even under strong mechanical shock. In the illustrated embodiment, the retaining portion 4 has a star-shaped form with three rays.

[0052] On the product side, the main body 1 has a structure containing a system of ventilation grooves 31 and dividers 33. The system provides that the through holes 14 are located at the bottom of the ventilation groove, that is, in a position where the surface on the product side is recessed.

[0053] In the embodiment of Figs. 1-6, the general shape of the main body with a flange 13 and an extended end surface 16 (which is connected to the packaging material) can be beneficial for the process of connecting the valve to the packaging material and for the stability of the connection. Namely, the bead defined by the flange, which is an outwardly protruding cuff, forms an input surface 17, which can be directly acted upon by the tool for connecting the valve to the packaging material. Thus, the energy - generally ultrasonic energy - introduced by the tool into the main body 1 for the connection process does not necessarily need to be introduced along the entire height (axial extent) of the main body, but only along the thickness of the flange 13. This makes the connection process more efficient compared to a situation in which the tool would be pressed against the end surface of the main body from the product side.

[0054] The instrument may, for example, be a sonotrode in the form of a tube with a tube diameter approximately corresponding to the diameter of flange 13.

[0055] However, flange 13 and extended end surface 16 are merely optional. In alternative embodiments, main body 1 does not have this structure. Main body 1, in these alternative embodiments of the invention, can also be configured to be welded to the packaging material in that the sonotrode acts on the end surface of the main body from the product side. Also, in these embodiments, the sonotrode used can optionally be in the form of a tube, with a tube diameter greater than the outer diameter of the region having a system of ventilation grooves and dividers. Alternatively, the sonotrode can have a flat outlet surface.

[0056] Figure 7 shows a corresponding embodiment without a flange. In the embodiment of Figures 1-6, the axially extending grooves extend from the product-side end of the main body. On the package side, the outer surface of the circumferential wall, in addition to the section with axially extending grooves, has a second smooth section 74, but does not have a flange, as in the previous embodiment. An energy-guiding rib (not visible in Figure 7) can be located on the package-side end surface formed by the circumferential wall.

[0057] Figure 8 shows another embodiment in which the recesses are not axially extending ribs, but are elliptical in shape. Thus, the outer surface of the circumferential wall not only has a first section with recesses and a second section 74 that is smooth on the packaging side, but also has a third, again smooth, section 75 on the product side.

[0058] Other recess shapes are also possible. Fig. 9 very schematically illustrates the possibility that the outer surface of the annular walls may have axially extending grooves 71 that do not extend to the product-side surface.

[0059] The pressure relief valve for use is placed inside a gas-tight flexible packaging in such a way that the annular end surface of the annular wall 11 is connected to the inner surface of the packaging, for example, by welding. Fig. 10 schematically shows a packaging with a valve. The main body 1 is welded to the packaging material 60. The packaging material has at least one gas passage (for example, at least one through hole or permeable section) in a place surrounded by the annular end surface. If there is excess pressure inside the packaging, the gas will cause the valve membrane 2 to rise from the bottom 12, and a gas passage will be created. The excess gas can then escape through the through hole(s) 14, between the valve membrane and the bottom and through the gas passage of the packaging.When there is no excess pressure inside the package, the membrane closes the package, adhering to the bottom, while the sealing liquid adheres to the bottom, and the valve membrane forms a seal by capillary forces.

Claims

1. A pressure relief valve comprising a main cup-shaped body (1) with a bottom (11) and a circumferential wall (12) adapted to be attached to a flexible packaging material, wherein the bottom (11) has at least one through hole (14) forming a passage through the main body, a valve membrane (2) adjacent to the main body on the packaging side in the region around at least one through hole (14), and a sealing liquid between the main body (1) and the valve membrane (2), characterized in that the circumferential wall has, on its outer surface, a plurality of recesses (71, 81).

2. The valve according to claim 1, in which the recesses (71, 81) are evenly distributed around the outer side of the circumferential wall (12).

3. A valve according to claim 1 or 2, wherein the recesses are axially extending grooves (71) extending from the product side end of the main body, with ribs (72) between the grooves (71).

4. A valve according to any of the preceding claims, wherein the outer surface of the circumferential wall, excluding the recesses (71, 81), is cylindrical or slightly conical.

5. A valve according to any of the preceding claims, wherein the circumferential wall comprises, on the end surface on the packaging side, an energy directing circumferential rib (18).

6. A valve according to any of the preceding claims, wherein the circumferential wall comprises, at the end on the packaging side, an outwardly projecting flange (13).

7. A valve according to any of the preceding claims, in which the outer surface of the circumferential wall has a structured section with recesses (71, 81) and additionally has a smooth section (74, 75) spaced axially from the structured section.

8. A valve according to any one of the preceding claims, wherein at least one component of the valve is made of a polymer composition containing a water-soluble polymer.

9. A valve according to any of the preceding claims, which is biodegradable.

10. A valve according to any one of the preceding claims, further comprising a permeable membrane (3) in the form of fabric attached to the main body (1) for closing at least one through hole (14) on the side of the product opposite to the side of the packaging.

11. A valve according to any of the preceding claims, in which the main body has a system of ventilation grooves with dividers between them, wherein the mouth of the through hole (14) or at least one of the through holes (14) is located in the ventilation groove.

12. A valve according to any of the preceding claims, further comprising a fixing part (4) fixed relative to the circumferential wall so that the valve membrane (2) is located between the bottom (11) and the fixing part (4).

13. A packaging material for packaging food products comprising a flexible, elastic packaging material (60) and a pressure relief valve according to any of the preceding claims, wherein the main body (1) is attached to the packaging material (60).

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