Valve, and package

Abstract

According to an aspect of the invention, there is provided a pressure reducing valve, the valve comprising a cup-shaped body (1) arranged to be fixed to a flexible packaging material, the body having a bottom (11) and a peripheral wall (12). The bottom has at least one through hole (14) forming a passage through the body. A valve diaphragm is attached to the body from the packaging side in a region surrounding the through hole (14), the body and the valve diaphragm having a sealing liquid therebetween. The valve diaphragm thereby covers the at least one through hole (14). On the packaging side, the bottom has a wick system (21, 22, 23) for containing a portion of the sealing liquid, the wick system comprising at least one outer wick (22, 23) having a main portion extending in a circumferential direction and having a radially extending portion (24, 25) extending radially from the main portion.

Description

Technical Field

[0001] This invention belongs to the field of pressure reducing valves for food packaging. Background Technology

[0002] Some food products, such as freshly roasted coffee beans or ground coffee, tend to release gas over time. Therefore, corresponding food packaging, such as coffee packets (coffee bags), has a pressure-relieving valve. The pressure-relieving valve allows gases generated inside the packaging (such as carbon dioxide) to escape while preventing ambient air from entering the packaging, thus preventing oxygen from entering and maintaining freshness.

[0003] Pressure reducing valves typically have a cup-shaped body, with the edges of the body's peripheral walls welded or bonded to the interior of the packaging material. Both the bottom of the body and the packaging have openings. A disc, acting as a valve diaphragm, rests against the bottom of the body and contains oil (e.g., silicone oil) as a sealing fluid between the bottom and the disc. If there is overpressure inside the packaging, gas flowing through the bottom opening lifts the disc, allowing gas to escape into the body and then out of the packaging through the packaging opening. When there is no overpressure inside the packaging, the disc against the bottom of the body ensures a leak-proof seal.

[0004] The advantage of these pressure-reducing valves is that they enable direct packaging of fresh food and delivery to the end customer without any intermediate repackaging. This offers ecological advantages in addition to ensuring freshness for the customer. However, pressure-reducing valves increase the environmental footprint of the packaging.

[0005] The internal overpressure required to trigger a pressure-reducing valve depends on the geometry of the body and the materials of the body, valve diaphragm, and sealing fluid. Furthermore, the pressure required to trigger the valve may vary depending on the packaging using the valve and its contents. According to existing technology, given a pressure-reducing valve and its components, the adhesion force is adjusted using sealing fluids of different compositions based on the required adhesion force and trigger pressure. However, fine-tuning the adhesion force by changing the chemical composition is challenging and requires experimentation. In particular, adjusting the adhesion force without affecting other properties is challenging—especially if other properties are considered when selecting the materials for the valve diaphragm and body, and there is no freedom to adjust these properties.

[0006] Therefore, the object of this invention is to overcome the shortcomings of pressure-reducing valves in the prior art. In particular, the object of this invention is to provide a method for setting adhesion force. Another object of this invention is to provide a pressure-reducing valve whose structure makes it suitable for manufacture using environmentally friendly materials. Summary of the Invention

[0007] According to one aspect of the invention, a pressure-reducing valve is provided, comprising a cup-shaped body configured to be fixed to a flexible packaging material, the body having a bottom and a peripheral wall. The bottom has at least one through-hole forming a channel through the body. A valve diaphragm abuts against the body from the packaging side (within the cup formed by the body) in a region surrounding the through-hole, with a sealing fluid between the body and the valve diaphragm. The valve diaphragm thereby covers at least one through-hole. On the packaging side, the bottom has an oil-retaining system for receiving a portion of the sealing fluid, the oil-retaining system including at least one outer oil-retaining groove having a main portion extending in a circumferential direction and a radial extension extending from the main portion in a radial direction.

[0008] The side of the bottom that faces away from the packaging side is referred to as the "product side" in this article.

[0009] The outer oil groove here is a groove located radially outward at the bottom, meaning it is positioned at a certain radial distance from at least one through-hole. Specifically, the outer oil groove can be closer to the peripheral wall than to the center of the bottom.

[0010] It is known in the art that the body may include an oil distribution groove on the bottom packaging side. An oil distribution groove is a shallow notch on the surface of the body against which the valve diaphragm rests. The oil distribution groove is used to contain excess sealing fluid and acts as its reservoir. An oil distribution groove is beneficial and often necessary to ensure that the space between the valve diaphragm and its resting surface is always uniformly supplied with sealing fluid.

[0011] According to this embodiment, in addition to this well-known function, the oiling tank also has a further function, namely, adjusting the adhesion force.

[0012] Specifically, the radial extension of the oil distribution groove effectively shortens the shortest path between the volume communicating with at least one through-hole along the valve diaphragm and any other hollow space. Here, the volume communicating with at least one through-hole can be formed by the through-hole itself or by a notch / groove around the through-hole, such as an inner oil distribution groove. According to the method described herein, the next other hollow space is the outer oil distribution groove itself. The length of this path is one of the parameters defining the trigger pressure: the shorter the path, the less adhesive force needs to be overcome to lift the pressure relief valve and release overpressure. Therefore, the adhesive force can be set using the length of this shortest path and the length of the extension itself in the embodiment.

[0013] In this way, both problems can be solved simultaneously.

[0014] First, when the triggering force needs to vary depending on the application, adjusting the length of the radial extension is sufficient. Therefore, the radial extension method allows all packages to use standard-sized bodies and valve diaphragms, as well as sealing fluids with a relatively high adhesion tendency. Due to the extension, the effective length of the path for the valve diaphragm to adhere to the body surface is reduced. Therefore, the pressure in the package rises until the valve is actuated, and the adhesion force to be overcome is also reduced; the larger the radial extension, the greater the reduction in adhesion force. Therefore, to adapt the valve to different applications requiring different actuation / trigger pressures, only one parameter needs to be changed: the size of the radial extension (radial dimension). This is a single geometric parameter, and its effect is predictable.

[0015] Secondly, this arrangement ensures that the valve diaphragm and its substrate surface are flat for different types of materials. According to existing technology, sometimes a curved diaphragm is required to prevent the adhesion force from becoming too strong, thus the elasticity of the diaphragm partially counteracts the adhesion force. However, this has the disadvantage that if the properties of the valve diaphragm material change, for example due to aging or moisture absorption, the properties of the pressure-reducing valve will also change. This tendency is particularly pronounced with environmentally friendly biodegradable materials. The method according to the invention ensures that the effective length of the path through which the valve diaphragm adheres to the substrate surface is reduced due to elongation. Thus, it provides a method to overcome the shortcomings of existing technology, enabling the use of environmentally friendly materials as valve materials.

[0016] The use of radial extensions allows all packages to use standard-sized bodies and valve diaphragms, as well as sealing fluids with relatively high adhesion tendency.

[0017] In an embodiment, at least one of the radial extensions is a radially inward extension.

[0018] In these embodiments, if the radially inward extension extends closer to the volume communicating with the orifice than any other structure, the shortest path along the valve diaphragm between the volume communicating with at least one through-hole and any other hollow space can lead from the volume communicating with the at least one through-hole to the innermost point of the inward extension.

[0019] In one set of embodiments, the body includes a plurality of outer oil channels. For example, the outer oil channels may include a ring array of at least two outer oil channels that together form a (discontinuous) ring.

[0020] Specifically, the outer oil troughs may include a circular array of first outer oil troughs and a circular array of second outer oil troughs, with the first outer oil troughs arranged around the second outer oil troughs. In such a configuration, the second outer oil troughs may be staggered relative to the first outer oil troughs, such that the second outer oil troughs cover the gaps between the first outer oil troughs, thereby eliminating radial lines from the bottom center to its periphery (to the peripheral wall) that are not interrupted by the outer oil troughs.

[0021] In embodiments where the outer oil distribution grooves are arranged in at least one circular array, each oil distribution groove may have an inward extension. If there are multiple circular arrays, it is sufficient for each oil distribution groove in one of the arrays to have one inward extension.

[0022] In an embodiment having two annular oil-spreading groove arrays, the radially inward extensions may be inward extensions of the first outer oil-spreading groove. They may extend through the gap between the second outer oil-spreading grooves, optionally extending radially inward to the location of the second outer oil-spreading groove.

[0023] In addition to the aforementioned function of adjusting adhesion, the radial extension can also balance the distribution of sealing fluid between the first and second outer oil grooves.

[0024] In an embodiment with two annular oil distribution groove arrays, the second outer oil distribution groove may include a radially outward extension that extends outward into the space between the first outer oil distribution grooves. This further improves the distribution of sealing fluid between the oil distribution grooves.

[0025] In addition to the outer oil trough, the oil trough system may also include an inner oil trough extending around at least one through-hole. The outer oil trough may be deeper than the inner oil trough (if any).

[0026] The body may include an extension adaptation groove within the plane defined by the valve diaphragm on the inner side of its peripheral wall. The extension adaptation groove provides space into which the valve diaphragm can expand, so that the valve diaphragm does not bulge when expanded, for example, when the valve diaphragm is damp.

[0027] The surface portion of the body against which the valve diaphragm rests can be flat, rather than the curved (arched) surface portion of existing valves. This flat structure can be advantageous, especially when the valve diaphragm and / or body are made of biodegradable materials, because the adhesion remains unchanged even when properties such as the material's elasticity are slightly altered due to moisture absorption or aging. The flat structure is particularly advantageous when combined with an extended adaptation groove, as this combination allows for precise placement of the valve diaphragm (by adapting its diameter to the inner diameter of the cup-shaped body) without the risk of the diaphragm arching or otherwise deforming upon expansion.

[0028] In some embodiments, if the packaging is intended to contain a fine-particle product, such as coffee powder (ground coffee), the valve further includes a permeable membrane attached to the bottom product side, covering at least one through-hole to prevent product blockage while allowing air permeability. The cocoa permeable membrane can be a fabric membrane. In this document, "fabric" is used to encompass all types of flexible materials made of interwoven fibers or yarns, including nonwovens, woven or knitted textiles, or other textile structures.

[0029] In one set of embodiments, particularly if the pressure reducing valve has a permeable membrane, the body has at least one notch on the product side, thus forming a recessed portion. At least one through-hole (or at least one of the through-holes) has its product-side opening in the recessed portion. Therefore, the through-hole opening on the product side is offset relative to the outermost plane of the product side. This means that if a permeable membrane is present, the through-hole opening is offset relative to the plane of the permeable membrane. The recessed portion can effectively constitute a venting groove system with spacers therebetween.

[0030] In this embodiment, the spacer has rounded edges. Therefore, the risk of damage to the permeable film is reduced when the packaging is subjected to mechanical stress.

[0031] In some embodiments, the pressure reducing valve also includes a retaining member. The retaining member is shaped to be positioned on the package side of the valve diaphragm. It prevents the valve diaphragm from falling out of the body even in the event of a significant mechanical shock to the pressure reducing valve. This type of shock is particularly likely to occur during transport and assembly if the pressure reducing valve is supplied in bulk. In the event of a mechanical shock, the retaining member holds the valve diaphragm in place, even if the adhesive force of the sealing fluid may be insufficient to do so. The retaining member can be held in place relative to the body by forming an undercut on the peripheral wall of the body, allowing the retaining member to be pressed into the body.

[0032] In some embodiments, the pressure reducing valve may be biodegradable, meaning all components can be made of biodegradable materials. As mentioned above, the oil distribution groove structure makes the valve particularly suitable for a diaphragm and / or a body made of biodegradable materials. In some embodiments, alternatively, other components may also be biodegradable.

[0033] In this document, “biodegradable” may mean biodegradable according to European standard EN 13432 (as of the end of 2021). Alternatively, it may mean biodegradable according to European standard EN 14995 (as of the end of 2021). Therefore, “biodegradable” specifically refers to “biodegradable according to EN 13432 and / or according to EN 14995”.

[0034] With regard to the water-soluble polymers mentioned in this article, these water-soluble polymers can be selectively degraded in wastewater treatment plants (aerobic biodegradability) according to DIN ENISO 9888 (as of the end of 2021); determined according to the so-called Zane-Whelans test.

[0035] In particular, at least one component of the pressure reducing valve, such as the body, may be made of a polymer composition comprising a water-soluble polymer. In some embodiments, the polymer composition further comprises a salt, particularly a hygroscopic salt.

[0036] In addition to containing a water-soluble polymer and a salt, the composition may also contain a plasticizer. The plasticizer may be selected from the group consisting of polyols (oligohydroxy compounds and polyhydroxy compounds) and low molecular weight amides.

[0037] In some embodiments, the body, and if present, a permeable membrane and a fixing component, are each made of a polymer composition comprising polyvinyl alcohol (PVOH) as a water-soluble polymer, a salt, and glycerol as a plasticizer.

[0038] In some embodiments, the valve diaphragm is made of a water-insoluble but biodegradable polymer composition, such as polyhydroxybutyrate (PHB).

[0039] In addition to relating to a pressure-reducing valve, the present invention also relates to packaging, particularly coffee bags for coffee beans or ground coffee. The packaging comprises a flexible, bendable packaging material and a pressure-reducing valve as described herein. The body of the pressure-reducing valve is attached to the packaging material. Specifically, the annular end face of the pressure-reducing valve may be attached to the packaging material, wherein a valve diaphragm (and, if present, a retaining element) is arranged in a cavity between the bottom of the body and the packaging material. The packaging material is generally airtight, but has openings or other permeable structures at locations surrounded by the peripheral walls of the body. Attached Figure Description

[0040] Embodiments of the present invention will now be described with reference to the accompanying drawings. In the drawings, the same numbers denote the same or corresponding elements. The drawings show:

[0041] Figure 1 Exploded view of the pressure reducing valve assembly;

[0042] Figure 2 The main view;

[0043] Figure 3 A sectional view of the assembled valve;

[0044] Figure 4 Different views of the main body;

[0045] Figure 5 Another view of the main body;

[0046] Figure 6 Another view of the assembled valve after sectional cutting; and

[0047] Figure 7 The valve in the packaging is shown schematically. Detailed Implementation

[0048] Figure 1 , 3 The pressure reducing valve shown in Figure 6 includes a body 1, which is also shown in... Figure 2 , 4 In part 5, the main body 1 has the overall shape of a flat-bottomed cup, with a bottom 11 and a peripheral wall 12. The bottom 11 has a sealing surface and a product side surface opposite to the sealing surface.

[0049] The peripheral wall 12 surrounds the sealing surface of the bottom 11 and has a flange 13, i.e., an outwardly projecting shoulder, at its end opposite to the bottom 11, making the annular end face 16 with the package-side energy guiding rib 18 wider. The bottom has at least one through-hole 14 (three through-holes 14 in the described embodiment), which is covered by a valve diaphragm 2 that abuts against the sealing surface of the bottom 11. A thin layer of sealing fluid, especially oil, such as silicone oil, is present between the bottom 11 and the valve diaphragm 2. Silicone oil is well known to be used for this purpose. Therefore, the sealing fluid will not be described in detail herein.

[0050] For this purpose, a pressure-reducing valve is placed within an airtight flexible package, wherein the annular end face 16 of the peripheral wall is bonded to the inner surface of the package by welding or other means. The packaging material has at least one gas passage (e.g., at least one small through-hole or permeable portion) at the location enclosed by the annular end face. If there is overpressure inside the package, the gas will cause the valve diaphragm 2 to rise from the bottom 11, thereby forming a gas passage. Excess gas can then escape through the through-hole 14, between the valve diaphragm and the bottom, and through the gas passage of the package. When there is no overpressure inside the package, the valve diaphragm seals the package by abutting against the bottom, and a sealing liquid adheres to the bottom and the valve diaphragm by capillary force to form a seal.

[0051] The body 1, located inside the peripheral wall 12 and within the plane defined by the valve diaphragm 2, includes an extended adaptation groove 41. This groove 41 has been found advantageous because the valve diaphragm 2 can be composed of a biodegradable polymer. It has been found that, compared to prior art valve diaphragm materials, these materials may tend to change size depending on environmental conditions. For example, they may swell slightly if exposed to moisture.

[0052] In this embodiment, the pressure reducing valve, in addition to the body 1 and the valve diaphragm 2, also has a permeable membrane 3. The permeable membrane 3 is gas-permeable compared to the valve diaphragm 2. For example, it can be a fabric, such as a non-woven fabric. The permeable membrane is attached to the bottom surface on the product side and at least covers the through-hole 14. The permeable membrane is useful if the packaging contains fine-particle products, especially ground coffee, as it prevents the product from clogging the opening and from contacting the sealing liquid and the valve diaphragm 2. It is not necessary for packaging containing products such as coffee beans or other large particles.

[0053] The permeable membrane 3 can be made of a polymer material, such as a thermoplastic fiber fabric. In some embodiments, the permeable membrane 3 can be welded to a body. For this purpose, the body has product-side energy guiding ribs 38 on the side facing the packaged product.

[0054] On the sealing side, the main body has multiple oil-spreading grooves. More specifically, the main body has an inner oil-spreading groove 21 surrounding the opening, and also has a ring of three first outer oil-spreading grooves 22 and a ring of three second outer oil-spreading grooves 23, with the first outer oil-spreading grooves 22 arranged around the second outer oil-spreading grooves 23. The outer oil-spreading grooves 22 and 23 generally extend circumferentially, and each outer oil-spreading groove has a main portion 27 extending circumferentially and parallel to the circumferential wall. Each second outer oil-spreading groove 23 has an outward extension 24 that extends radially outward from the main portion 27 into the gap between the first outer oil-spreading grooves 22. Each of the first outer oil-spreading grooves 22 has an inward extension 25 that extends radially inward from the main portion 27 into the gap between the second outer oil-spreading grooves 23 and even further radially inward.

[0055] In this paper, “radial” and “outward” or “inward” or “circumferential” refer to the axis 10 of the reference body; the presence of a central axis does not necessarily imply axisymmetry, although such symmetry is an option.

[0056] The outer oil channels function as reservoirs for the sealing fluid. For this purpose, they are located radially so as to be covered by the valve diaphragm (see, for example...). Figure 3 or Figure 6 For example, when a valve (e.g., during transport before it is bonded to the packaging or during transport of a package with a valve) is subjected to temporary mechanical loads, the sealant may be forced to leak from between the bottom 11 and the valve diaphragm 2. The oil distribution groove ensures that capillary action can subsequently draw the sealant back from the oil distribution groove beneath the valve diaphragm. Similar factors are considered in the manufacturing process: due to the presence of the oil distribution groove, it is sufficient to drip a single drop of sealant onto the bottom or diaphragm; the oil distribution groove ensures good distribution of the sealant and that the sealing film adheres evenly to the bottom around the through-hole 14.

[0057] In addition to this well-known function, the special structure of the outer oil channels 22 and 23 makes it possible to better control the adhesion force. That is, the distance between the inner oil channel 21 and the outer oil channels 22 and 23 defines the minimum path length p. l Along this path, adhesion forces must be overcome to trigger the pressure-reducing valve by lifting the valve diaphragm 2 from the bottom 11. If there is no internal oil groove, then the amount of concern is the distance between the through-hole 14 and the inward extension 25.

[0058] like Figure 5 As shown, the path length p l The length of the inward extension 25 can be controlled by selecting the length of the extension.

[0059] Both the outward extension 24 and the inward extension 25 have the further function of distributing the sealing fluid between the oil distribution grooves. For example, due to the presence of the outward extension 24 and the inward extension 25, the sealing fluid can communicate between the first outer oil distribution groove and the second outer oil distribution groove, as well as between different first oil distribution grooves and different second oil distribution grooves.

[0060] The system includes an annular array having at least two (three in the illustrated embodiment) first external oil distribution grooves 22 and / or an annular array having at least two (three in the illustrated embodiment) second external oil distribution grooves 23. However, compared with an arrangement where the oil distribution grooves are in an uninterrupted annular shape, the system has the advantage that the sealing fluid can be well distributed along the edge of the bottom 11 even when the pressure reducing valve remains in a constant vertical orientation for a long time.

[0061] In this embodiment, the pressure reducing valve, in addition to the body 1, the valve diaphragm 2, and, depending on the case, a permeable membrane 2, also includes a retaining member 4. The retaining member 4 is optional and can serve as a spacer between the flexible packaging material and the valve diaphragm 2 to ensure that the valve diaphragm 2 does not shift even in the event of severe mechanical impact. In the illustrated embodiment, the retaining member 4 is a star shape with three spokes. It has a first distance retaining rib 51 and a second distance retaining rib 52. The overall star shape and the distance retaining ribs 51, 52 constitute a material-saving shape while maintaining a stable orientation. Furthermore, the star shape ensures some flexibility for the retaining member 4.

[0062] For example, such as Figure 6 As shown, the shape of the peripheral wall 12 forms a slight undercut 42 inside, and the inner surface of the body is slightly tapered. Due to this undercut shape, the fixing member 4 can be snapped into the body and held there due to its elasticity.

[0063] On the product-facing side, the main body 1 is configured to include a venting channel system 31 and a spacer 33. This system positions the through-hole 14 at the bottom of the venting channel, i.e., at a recessed location on the product-side surface. The radial channels 32 of the venting channel system 31 ensure that gas diffused through the breathable membrane into the venting channels can reach the through-hole 14. Therefore, the gas encounters less resistance and can diffuse through a relatively large surface area because the membrane is not pressed against a flat surface due to overpressure within the packaging. Conversely, the spacer 33 keeps it away from the plane where the through-hole 14 opens.

[0064] Another effect of the ventilation groove system is to prevent the breathable membrane 3 from adhering to the body in the area around the through-hole 14. Such adhesion may occur, for example, during the process of bonding the breathable membrane 3 to the body by ultrasonic welding.

[0065] For example, such as Figure 5 As shown, the spacer 33 has a rounded edge 35, which reduces the risk of damage to the permeable film when the packaging is subjected to mechanical stress.

[0066] The overall shape of the body, with flange 13 and widened end face 16 (which adheres to the packaging material), further improves the process of bonding the pressure reducing valve to the packaging material and the stability of the bond. Specifically, the shoulder defined by the flange as an outwardly projecting shoulder forms a coupling input surface 17, which the tool used to bond the pressure reducing valve to the packaging material can directly act upon. Therefore, the energy (typically ultrasonic energy) coupled into the body 1 for the bonding process does not need to be coupled across the entire height (axial extension) of the body, but only through the thickness of the flange 13. This makes the bonding process more efficient compared to the case where the tool presses against the product-side end face of the body.

[0067] The tool could be, for example, a tubular ultrasonic generator with a tube diameter that approximately corresponds to the diameter of flange 13.

[0068] However, flange 13 and widened end face 16 are only optional. In alternative embodiments, body 1 does not have this structure. In these alternative embodiments, body 1 can also be welded to packaging material by applying an ultrasonic generator to the product-side end face of the body. Also in these embodiments, the ultrasonic generator used can optionally be tubular, with a diameter larger than the outer diameter of the area having the venting system and spacers. However, alternatively, the ultrasonic generator can have a flat outer coupling surface.

[0069] In the embodiment described, the main body 1, the fixing component 4, and the permeable membrane 3 are all made of a polymer composition containing salt in addition to a water-soluble polymer.

[0070] - The main body 1 and the fixing component 4 are injection molded from a polymer composition comprising, for example, PVOH obtained by saponifying polyvinyl ester, a salt (especially sodium chloride), and glycerol. The polymer compositions of the main body and the fixing component can be the same.

[0071] - A permeable membrane is a fibrous fabric made of a polymer composition, which also contains PVOH obtained by, for example, saponification of polyvinyl ester, salts (especially sodium chloride) and glycerol.

[0072] The valve diaphragm 2 is made of PHB material.

[0073] Therefore, all components are biodegradable.

[0074] Figure 7 The diagram schematically shows a package with a pressure reducing valve. The main body 1 is welded to the packaging material 60, which has a through hole 61 for gas release.

Claims

1. A pressure reducing valve, comprising: A cup-shaped body (1) configured to be fixed to a flexible packaging material has a bottom (11) and a peripheral wall (12), the bottom (11) having at least one through hole (14) forming a channel through the body; a valve diaphragm (2) abutting the body from the packaging side in an area surrounding the at least one through hole (14); and a sealing liquid located between the body (1) and the valve diaphragm (2), characterized in that the bottom (11) has an oiling system on the packaging side for containing a portion of the sealing liquid, the oiling system including at least one outer oiling groove (22, 23) having a main portion (27) extending circumferentially and radial extensions (24, 25) extending radially from the main portion (27).

2. The valve according to claim 1, wherein, The oil distribution system includes at least one annular array consisting of at least two first outer oil distribution tanks (22).

3. The valve according to claim 2, wherein, The oil trough system further includes at least one annular array having at least two second outer oil troughs (23), the first outer oil trough (22) being arranged around the second outer oil trough (23), and the second outer oil troughs being staggered relative to the first outer oil trough.

4. The valve according to claim 3, wherein at least one first outer oil groove has a radial extension (25) that extends inwardly to the second outer oil groove (23).

5. The valve according to claim 3 or 4, wherein at least one second outer oil groove has a radial extension (24) that extends outward to the first outer oil groove (22).

6. The valve according to claim 3 or 4, wherein the oil distribution system further comprises an inner oil distribution groove (21) extending around the at least one through hole (14).

7. The valve according to claim 6, wherein the at least one outer oil groove (22, 23) is deeper than the inner oil groove (21).

8. The valve according to claim 1, wherein at least one of the radial extension or radial extension (25) is an inward extension, and wherein, when the valve diaphragm (2) is abutted against the body, the valve diaphragm (2) extends from the volume connected to at least one through hole (14) to the innermost point of the inward extension along the shortest path between the volume connected to at least one through hole (14) and any other hollow space.

9. The valve according to claim 1, wherein at least one component of the valve is made of a polymer composition comprising a water-soluble polymer.

10. The valve according to claim 1, wherein all components of the valve are biodegradable.

11. The valve according to claim 1 further includes a permeable membrane (3), the permeable membrane being a fabric fixed to the body (1) for covering at least one through-hole (14) on the product side opposite to the packaging side.

12. The valve according to claim 1, wherein the body has a venting groove system, spacers are provided between the venting grooves, and at least one of the through holes (14) or the opening of the through hole (14) is located within the venting groove.

13. The valve according to claim 1 further includes a fixing member (4) fixed relative to the peripheral wall, such that the valve diaphragm (2) is sandwiched between the bottom (11) and the fixing member (4).

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

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