Valves and Packages

Abstract

According to one aspect of the present invention, a pressure relief valve is provided, comprising a cup-shaped body (1) having a bottom (11) and a peripheral wall (12) and fastened to a flexible packaging material. The bottom has at least one through hole (14) forming a passage through the body. A valve membrane abuts the body on the packaging side in an area around the through hole (14), and there is a sealing liquid between the body and the valve membrane. The valve membrane thereby covers the at least one through hole (14). The peripheral wall (12) has a number of recesses (71) on its outer side.

Description

[Technical field]

[0001] The present invention is in the field of pressure relief valves for food packages. [Background technology]

[0002] Certain foods, such as freshly roasted coffee beans or coffee powder, tend to degas for a while. Therefore, some food packages, such as coffee pouches, have a pressure relief valve. The pressure relief valve allows gases generated inside the package, such as carbon dioxide, to escape while preventing ambient air from entering the package, so that oxygen does not enter the package and freshness is maintained.

[0003] A pressure relief valve usually has a cup-shaped body, and the peripheral wall of the body among the edges is welded or glued to the inside of the packaging material. The bottom of the body and the package each have an opening. At the bottom of the body there is a disk as a valve membrane, and between the bottom and the disk there is oil, e.g. silicone oil, which acts as a sealing liquid. When there is overpressure in the package, the gas communicating through the opening of the bottom lifts the disk, so that the gas can escape to the inside of the body and from there to the outside of the package through the opening of the package. When there is no overpressure in the package, the disk abutting the bottom of the body ensures a leak-proof seal.

[0004] This type of pressure relief valve is beneficial in that it allows fresh food products to be directly packaged and delivered to the end customer without the need for intermediate repackaging. In addition to ensuring freshness for the customer, this also has benefits from an ecological perspective. However, pressure relief valves increase the environmental footprint of the package. Summary of the Invention [Problem to be solved by the invention]

[0005] It is therefore an object of the present invention to overcome the shortcomings of prior art pressure relief valves, and to provide a pressure relief valve having a geometry specifically designed for optimum efficiency and minimal environmental footprint. [Means for solving the problem]

[0006] The present invention relates to a pressure relief valve, the valve comprises a cup-shaped body having a bottom and a peripheral wall and fastened to a flexible packaging material. The bottom has at least one through hole forming a passage through the body. The valve membrane is in contact with the body on the packaging side (in the cup formed by the body) in the area around the through hole, and there is a sealing liquid between the body and the valve membrane. According to one aspect of the present invention, the peripheral wall has a number of recesses on its outer side.

[0007] The side of the bottom opposite the package side is referred to herein as the "product side." The relatively easy implementation method of the external recess has been found to be suitable for reducing the amount of material required for the pressure relief valve without compromising function or mechanical stability.

[0008] The depressions may in particular have the form of axially extending grooves with ribs between them. The grooves may be regularly arranged around the circumference of the body.

[0009] Cylindrical parts having a ribbed structure on the outside are known in the art, for example as caps for beverage bottles or other rotatable parts, in that the ribbed structure improves the grip and thus makes it easier to manually rotate the respective part. However, the body of the pressure relief valve is designed to be fixed to the package and not rotate. Nevertheless, it is the insight of the present invention that a structure having grooves and ribs or other indentations on the outside of the peripheral wall of the body is advantageous in that it helps to improve mechanical stability given a certain material volume, or from a different perspective, helps to reduce the material volume required to achieve a certain mechanical stability.

[0010] In particular, it has been found that a structure of recesses, in particular having the shape of axially extending grooves, acts to stiffen the body.

[0011] The overall shape of the body may be such that the outer surface essentially corresponds to a disk-shaped body, i.e. a cylindrical or slightly conical surface with a relatively small axial extension, with a recess on the outer surface and possibly with an outwardly projecting flange, so that machines developed to handle prior art pressure relief valves without recesses can be used to process the present pressure relief valve, in particular for mounting inside the package. The approach of the present invention therefore does not require additional investments in machines.

[0012] The depressions may be evenly distributed around the circumference of the body with equal spacing between adjacent depressions.

[0013] The number of depressions may be, for example, 10-40, particularly 15-30. Where the depressions are axially extending grooves, their shape in horizontal cross section (cross section through a plane perpendicular to the axis) may be continuously curved and concave. In particular, the depressions may be shallow in that the central angle of the curved section is less than 180°, in particular less than 120° or less than 90°.

[0014] In one group of embodiments, the peripheral wall of the body has a package side section that is an outwardly projecting flange in addition to the structured section having a recess. The structured section may extend to the product end of the body.

[0015] In one group of embodiments, the package section is the portion having a smooth outer surface in that it does not have grooves or ribs. Also in this group, the structured section may optionally extend to the product end of the body.

[0016] As an alternative to the structured section extending to the product end of the body, the outer surface of the peripheral wall of the body may have a further, but smooth, third section on the product side of the structured section, whereby the recess in this alternative form is limited to a central (axially) portion of the outer surface of the peripheral wall.

[0017] The bottom of the body is not affected by the recess in the peripheral wall. On the product side, the bottom of the body may be provided with at least one grease groove for accommodating a reservoir of sealing liquid.

[0018] In one group of embodiments, especially when the valve has a permeable membrane, the bottom of the body has at least one recess 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 mouth in the recessed portion. This means that the mouth of the through hole on the product side is offset with respect to the outermost product side surface. This means that, if a permeable membrane is present, the mouth of the through hole is offset with respect to the plane of the permeable membrane. The recessed portion can effectively constitute a system of vent grooves with spacers between them.

[0019] In an embodiment, the spacers have rounded edges, so there is less risk of damaging the permeable membrane when the package is subjected to mechanical stress.

[0020] In an embodiment, when the package contains a particulate product such as coffee powder (ground coffee), the valve further comprises a permeable membrane attached to the bottom product side, which is permeable to gas while covering at least one through hole so that the product does not clog the through opening. The permeable membrane may be a fabric membrane. In this specification, "fabric" is used to cover all kinds of flexible materials from interlocked fibers or yarns or threads, including nonwovens, woven or knitted fabrics or other textile structures.

[0021] In an embodiment, the valve further comprises a fixing part. The fixing part is shaped to rest on the package side of the valve membrane. This prevents the valve membrane from falling off from the body even in situations where the valve is subjected to significant mechanical shock. If the valve is provided as a bulk material, it may be subjected to such shock especially during the transportation and assembly process. In situations of mechanical shock, the fixing part holds the valve membrane in place even if the adhesion by the sealing liquid is not sufficient. The fixing part may be held against the body by a peripheral wall of the body forming an undercut, so that the fixing part can click into the body.

[0022] In embodiments, the valve may be biodegradable, ie, all components may be made from biodegradable materials.

[0023] In this specification, "biodegradable" may mean biologically degradable according to European standard EN 13432 (as of the end of 2021). Additionally or alternatively, it may mean biologically degradable according to European standard EN 14995 (as of the end of 2021). Thus, "biodegradable" refers in particular to "biodegradable according to EN 13432 and / or EN 14995".

[0024] Insofar as water-soluble polymers are mentioned in this specification, such water-soluble polymers may optionally be degradable in sewage treatment plants (aerobic biodegradable) as determined according to the so-called Zahn-Wellens test in accordance with DIN EN ISO9888 (as of the end of 2021).

[0025] In particular, at least one component of the valve, such as the body, may be made from a polymeric composition comprising a water-soluble polymer. In embodiments, the polymeric composition further comprises a salt, in particular a hygroscopic salt.

[0026] In addition to including a water-soluble polymer and a salt, the composition may include a plasticizer, which may be selected from the group consisting of polyols (oligo- and polyhydroxy compounds) and low molecular weight amides.

[0027] In an embodiment, each of the body and, if present, the permeable membrane and the fixing portion is a polymer composition comprising polyvinyl alcohol (PVOH) as a water-soluble polymer, a salt, and glycerin as a plasticizer.

[0028] In an embodiment, the valve membrane is a polymeric composition that is not water soluble but is biodegradable, such as polyhydroxybutyrate (PHB).

[0029] In addition to relating to a pressure relief valve, the present invention also relates to a package, in particular a coffee pouch for coffee beans or ground coffee. The package comprises a flexible, pliable packaging material as described herein, and a pressure relief valve. The body of the pressure relief valve is attached to the packaging material. In particular, the annular end face of the pressure relief valve may be attached to the packaging material with the valve membrane (and the fixing part, if present) located in the hollow space between the bottom of the body and the packaging material. The packaging material is generally airtight, but has an opening or other permeable structure at a position surrounded by the peripheral wall of the body.

[0030] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings, in which like numbers indicate like or corresponding elements. [Brief description of the drawings]

[0031] [Figure 1] FIG. 2 is an exploded view of the components of the pressure relief valve. [Diagram 2] This is the main body in the figure. [Diagram 3] FIG. 1 shows a cut and assembled valve. [Figure 4]This is the main body from a different perspective. [Diagram 5] FIG. [Figure 6] FIG. 13 is a further view of the cut and assembled valve. [Figure 7] 1 is an alternative embodiment of the body. [Figure 8] 1 is yet a further alternative embodiment of the body. [Figure 9] FIG. 13 is a schematic side view of yet another embodiment of a body. [Figure 10] FIG. 2 is a schematic diagram of a valve in a package. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] The pressure relief valve shown in Figures 1, 3 and 6 comprises a body 1, also shown in Figures 2, 4 and 5. The body 1 has the overall shape of a flat cup having a bottom 11 and a peripheral wall 12. The bottom 11 has a sealing surface and a product surface opposite the sealing surface.

[0033] The peripheral wall 12 surrounds the sealing surface of the bottom 11. It has a substantially cylindrical or slightly conical outer surface with axially extending grooves 71 arranged at regular distances and with ribs 72 between them. The axially extending ribs 72 increase the mechanical stability even when the peripheral wall 12 is relatively thin, i.e. made using a minimum of plastic material.

[0034] The peripheral wall 12 in this embodiment further has a flange 13, i.e. an outwardly projecting collar, at its end opposite the bottom 11, which results in a wider annular end face 16 carrying the package-side energy-guiding rib 18. The bottom as at least one through-hole 14 (in the embodiment shown there are three through-holes 14) is covered by the valve membrane 2 which contacts the bottom 11 on its sealing surface. Between the bottom 11 and the valve membrane 2 there is a thin layer of sealing liquid, in particular oil, e.g. silicone oil.

[0035] As used herein, "circumferential" as well as "radial" or "outer" or "inner" are meant to refer to the axis 10 of the body.

[0036] The body 1 is provided, inside the peripheral wall 12 and in the plane defined by the valve membrane 2, with an extended accommodation groove 41 capable of accommodating any extended portion of the valve membrane so that the valve membrane does not bulge on inflation, for example if it absorbs some moisture.

[0037] In an embodiment, the pressure relief valve has a permeable membrane 3 in addition to the body 1 and the valve membrane 2. The permeable membrane 3 may be a fabric, for example a nonwoven fabric. The permeable membrane is attached to the bottom product side surface and covers at least the through opening 14.

[0038] On the sealing face side, the body has a number of grease grooves. More specifically, the body has an inner grease groove 21 surrounding the opening, and further has a ring of three first outer grease grooves 22 and a ring of three second outer grease grooves 23, the first outer grease grooves 23 being arranged around the second outer grease grooves 22.

[0039] The outer grease grooves have the function of reservoirs for sealing liquid. For this purpose, they are located in a radial position so that they are covered by the valve membrane (see, for example, FIG. 3 or FIG. 6).

[0040] In an embodiment, the pressure relief valve has a fixed part 4 in addition to the body 1 and the valve membrane 2, possibly in addition to the permeable membrane 2. The fixed part 4 is optional and may function as a spacer between the flexible packaging material and the valve membrane 2, ensuring that the valve membrane 2 cannot be displaced even in the event of severe mechanical violent vibration. In the illustrated embodiment, the fixed part 4 is star-shaped with three rays.

[0041] On the product side, the body 1 is constructed with a system of ventilation grooves 31 and spacers 33. The system is such that the through holes 14 are at the bottom of the ventilation grooves, i.e. in the position where the product side surface is recessed.

[0042] In the embodiment of Figures 1-6, the overall shape of the body with the flange 13 and the wide end face 16 (joined to the packaging material) may be beneficial for the process of joining the valve to the packaging material and the stability of the bond: the shoulder defined by the flange, which is an outwardly protruding collar, provides a bonding surface 17 on which the tool for joining the valve to the packaging material can directly act. Thereby, the energy coupled by the tool into the body 1 for the bonding process (usually ultrasonic energy) does not have to be coupled through 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 a situation where the tool presses against the product-side end face of the body.

[0043] The tool may for example be a tube-shaped sonotrode with a tube diameter that corresponds approximately to the diameter of the flange 13 .

[0044] However, the flange 13 and the wide end face 16 are merely optional. In alternative embodiments, the body 1 does not have this structure. Also in these alternative embodiments, the body 1 may be weldable to the packaging material in that the sonotrode impinges on the product side end face of the body. Also in these embodiments, the sonotrode used may optionally be tubular in shape, the tube diameter being larger than the outside diameter of the area with the system of ventilation grooves and spacers. However, alternatively, the sonotrode may have a flat outcoupling face.

[0045] Figure 7 shows an embodiment without a flange. As in the embodiment of Figures 1 to 6, an axially extending groove extends from the product end of the body. On the package side, in addition to the section with the axially extending groove, the outer surface of the peripheral wall has a second smooth section 74, as in the previous embodiment, but does not have a flange. An energy-guiding rib (not visible in Figure 7) may be arranged on the package side end surface formed by the peripheral wall.

[0046] Figure 8 shows yet a further variation in which the recesses have an elliptical shape rather than axially extending ribs, so that the outer surface of the peripheral wall not only has a first section with the recesses and a second section 74 which is a smooth section facing the package, but also a third, also smooth section 75 facing the product.

[0047] Other shapes of recesses are possible. Figure 9 shows very diagrammatically the possibility that the outer surface of the peripheral wall can have an axially extending groove 71 that does not extend to the product side surface.

[0048] The pressure relief valve for use is placed inside an airtight flexible package in that the annular end face of the peripheral wall 11 is joined to the package inner surface, for example by welding. Figure 10 shows a package with a valve diagrammatically. The body 1 is welded to a packaging material 60. The packaging material has at least one gas passage (for example at least one through hole or permeable section) at the location surrounded by the annular end face. When there is overpressure in the package, the gas lifts the valve membrane 2 from the bottom 12, forming a gas passage. The excess gas can then escape through the through hole 14, between the valve membrane and the bottom, and through the gas passage of the package. When there is no overpressure in the package, the membrane closes the package by contacting the bottom, and capillary forces cause the sealing liquid to adhere to the bottom and the valve membrane to form a seal.

Claims

1. 1. A pressure relief valve comprising: a cup-shaped body (1) having a bottom (11) and a peripheral wall (12) and equipped to be fastened to a flexible packaging material, said bottom (11) having at least one through hole (14) forming a passage through said body (1); a valve membrane (2) contacting said body on the packaging side in the area around said at least one through hole (14); and a sealing liquid between said body (1) and said valve membrane (2), characterized in that said peripheral wall has a number of recesses (71, 81) on its outer surface.

2. 2. A valve as claimed in claim 1, wherein said recesses (71, 81) are arranged evenly distributed around the outside of said peripheral wall (12).

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

4. 10. A valve according to any one of the preceding claims, wherein the outer surface of the peripheral wall, except for the recess (71, 81), is cylindrical or slightly conical.

5. 10. A valve according to any one of the preceding claims, wherein the peripheral wall is provided at its package side end face with an energy directing circumferential rib (18).

6. 10. A valve as claimed in any one of the preceding claims, wherein the peripheral wall is provided at the packaging end with an outwardly projecting flange (13).

7. 10. The valve of claim 1, wherein the outer surface of the peripheral wall has a structured section having the recesses (71, 81) and further has a smooth section (74, 75) axially spaced from the structured section.

8. 10. The valve of any one of the preceding claims, wherein at least one component of the valve is made from a polymer composition comprising a water soluble polymer.

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

10. 10. The valve according to any one of the preceding claims, further comprising a permeable membrane (3) of fabric secured to the body (1) so as to cover the at least one through hole (14) on a product side opposite the packaging side.

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

12. 10. A valve according to any one of the preceding claims, further comprising a fixing part (4) fixed relative to the peripheral wall, such that the valve membrane (2) is sandwiched between the bottom part (11) and the fixing part (4).

13. 10. A package for packaging food products, comprising a flexible, pliable packaging material (60) and a pressure relief valve according to any one of the preceding claims, said body (1) being attached to said packaging material (60).

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