Valve, and package

Abstract

According to one aspect of the invention, there is provided a pressure relief valve comprising a body (1) configured to be fastened to a flexible packaging material. The body has at least one through-hole (14) forming a passage through the body; the valve diaphragm (2) rests from the packaging side to the body in a region located around the bore (14); and a sealing liquid located between the main body (1) and the valve diaphragm (2). The valve comprises a water-soluble polymer, which means that at least one component of the valve, such as the body (1), is made of a polymer composition comprising a water-soluble polymer.

Description

Technical Field

[0001] The invention belongs to the field of pressure reducing valves used for food packaging. Background Art

[0002] Certain food products, such as freshly roasted coffee beans or ground coffee, have a tendency to outgas over a period of time. Therefore, corresponding food packaging, such as coffee bags (coffee bags), has a pressure relief valve. The pressure relief valve allows gases (such as carbon dioxide) generated inside the packaging to escape while preventing the surrounding air from entering the packaging, so that no oxygen can enter the packaging, thereby maintaining freshness.

[0003] The pressure relief valve usually has a cup-shaped body, wherein the edge of the peripheral wall of the body is welded or glued to the inside of the packaging material. The bottom of the body and the packaging both have openings. The bottom of the body rests against a disc serving as a valve diaphragm, with oil, for example silicone oil, between the bottom and the disc. If there is an overpressure in the packaging, the gas communicated through the bottom opening lifts the disc so that the gas can escape into the interior of the body and from there out of the packaging through the packaging opening. When there is no overpressure in the packaging, the disc resting against the bottom of the body ensures a leak-proof seal.

[0004] The advantage of such pressure relief valves is that they make it possible to pack fresh food directly and deliver it to the end customer without any intermediate repackaging. This has ecological advantages in addition to ensuring freshness for the customer. However, pressure relief valves increase the environmental footprint of the packaging.

[0005] It would be desirable to have further ways to improve the ecological balance of the packaging of freshly roasted coffee and other roasted products that generate gas after the roasting process. Summary of the invention

[0006] According to one aspect of the present invention, there is provided a pressure relief valve, the valve comprising: a body, which is configured to be fixed to a flexible packaging material, the body having at least one through hole, the through hole forming a passage through the body; a valve membrane, which is attached to the body from the packaging side in an area around the hole; and a sealing liquid between the body and the valve membrane. The valve comprises a water-soluble polymer, which means that at least one component of the valve (e.g., the body or an additional component, such as a fixing part or a permeable membrane described below) is made of a polymer composition comprising a water-soluble polymer.

[0007] A polymer in the present context is considered water soluble if it dissolves in water at a temperature at which water is liquid at normal pressure. In some embodiments, a water soluble polymer material is water soluble at room temperature, but in other embodiments may only be soluble at elevated temperatures (e.g., 60° C.) (thus having only hot water solubility).

[0008] The body itself is dimensionally stable. The body can be configured to be cup-shaped and have a bottom and a peripheral wall surrounding the bottom, the annular end face of the peripheral wall being attachable to the packaging material and thus fastened to the flexible packaging material. The bottom then comprises at least one through hole, which forms a passage through the bottom for the gas generated in the package. The valve membrane is arranged on the packaging side of the bottom (in the cup formed by the body) and covers the at least one through hole. The side of the bottom opposite to the packaging side is referred to herein as the "product side".

[0009] In some embodiments, if the package is used to contain fine-grained products, such as coffee powder (ground coffee), the valve further comprises a permeable membrane attached to the product side of the bottom, covering at least one through hole to prevent the product from blocking the through hole, while being breathable. The permeable membrane may be a fabric membrane. In this article, "fabric" is used to cover all types of flexible materials interlaced by fibers or yarns or threads, including non-woven fabrics, woven or knitted textiles or other textile structures.

[0010] In some embodiments, the valve further comprises a fixing member. The fixing member is shaped to be placed on the packaging side of the valve diaphragm. It prevents the valve diaphragm from falling out of the body even in the event of a large mechanical shock to the valve. The valve may be particularly exposed to such shocks during transport and assembly if the valve is provided in the form of bulk material. In the event of a mechanical shock, the fixing member enables the valve diaphragm to remain in place, even if the adhesion of the sealing liquid may not be sufficient to do so. The fixing member may be fixed relative to the body by forming an undercut in the peripheral wall of the body so that the fixing member can be pressed into the body.

[0011] The water solubility of the polymer offers advantages in recycling processes, whether composting or paper recycling.

[0012] Although water-soluble polymers may be biodegradable, not all water-soluble polymers are biodegradable. In addition to being water-soluble, the water-soluble polymers of valves may also be biodegradable.

[0013] In this document, "biodegradable" may mean biodegradable according to European Standard EN 13432 (as of the end of 2021). Additionally or alternatively, it may mean biodegradable according to European Standard EN 14995 (as of the end of 2021). Therefore, "biodegradable" particularly means "biodegradable according to EN 13432 and / or according to EN 14995".

[0014] In the case of water-soluble polymers mentioned in this context, such water-soluble polymers are selectively degradable in sewage treatment plants in accordance with DIN EN ISO 9888 (as of the end of 2021) (aerobic biodegradability); determined according to the so-called Zahn-Whillens test.

[0015] In some embodiments, all components of the valve, ie the body, the valve membrane, and (if present) the permeable membrane and / or the fixing member, are made of biodegradable materials.

[0016] In some embodiments, although the valve comprises a water-soluble polymer, for example as the material of the body and / or (if applicable) the fixing member and / or the permeable membrane, the valve membrane is not water-soluble.

[0017] In some embodiments, at least one component is made of a polymer composition belonging to a first class of polymer compositions. The first class of polymer compositions is water soluble.

[0018] In one set of embodiments, the first polymer composition comprises a salt in addition to the water-soluble polymer.

[0019] The salt content may be at least 1% or at least 2% or at least 3% or at least 10% or at least 15% or even at least 20% or at least 25%, with a maximum of 55% or 40% or 35%.Herein, unless otherwise stated, all percentages are by weight.

[0020] The salt may be a hygroscopic salt.

[0021] The salt may include an alkali metal salt, an alkaline earth metal salt or an aluminum salt and / or mixtures thereof. Specific examples include NaCl, sodium citrate and the corresponding potassium analogs, magnesium chloride and / or mixtures thereof.

[0022] On the one hand, in the first type of polymer composition, the salt can act as a lubricant for the polymer, and the addition of the salt to the polymer can increase the melt index (MFI), thereby improving the hot melt processing performance of the polymer composition.

[0023] Thus, if the body and / or, if applicable, the fixing element is made of a first polymer composition comprising a salt, they can be manufactured by injection molding or other molding techniques. The same applies if the body and / or the fixing element is made of a different polymer composition, in particular a first polymer composition not comprising a salt.

[0024] Furthermore, salt has been found to increase solubility, decomposition and biodegradation rates, for example for composting. Adding salt can make a polymer compostable at home, whereas without salt it can only be composted industrially but not at home. Thus, the salt content can be used to adjust the properties of the polymer composition depending on the intended use and the intended recycling process.

[0025] Specifically, regardless of whether the first type of polymer composition contains salt, the water-soluble polymer of the first type of polymer composition may include at least one of polyvinyl alcohol (PVOH), cellulose ether polymer, butene glycol-vinyl alcohol copolymer (BVOH), polyvinyl butyral (PVB) and ethylene-vinyl alcohol copolymer (EVOH).

[0026] The first type of polymer composition may include, in particular, a water-soluble polymer that is a vinyl alcohol polymer or copolymer, or a mixture or blend of two or more vinyl alcohol copolymers. That is, the water-soluble polymer may be a polymer having a plurality of vinyl alcohol [CH2CH(OH)] groups in the polymer chain. These polymers include the above-mentioned PVOH, BVOH and EVOH, as well as other polymers.

[0027] If the water-soluble polymer comprises a mixture or blend of two or more vinyl alcohol copolymers, the copolymers may differ in molar mass, molecular structure (eg, branching), type and amount of comonomer, or other varying parameters.

[0028] Thus, the polymer of the first polymer composition may be a vinyl alcohol-containing, in particular a vinyl alcohol-rich copolymer or a vinyl alcohol homopolymer. In an embodiment, the polymer may contain >75%, in particular >90% monomer units bearing OH units.

[0029] The water-soluble polymer may contain other polar comonomers. Examples include maleic acid and maleic anhydride, fumaric acid and itaconic acid.

[0030] The degree of hydrolysis of water-soluble polymers, especially polyvinyl alcohol (PVOH), can reach 70% to 99.9%. The degree of saponification is related to the oxygen barrier performance. In particular, the degree of hydrolysis can reach at least 90%, or at least 94%, or even at least 96%. The higher the degree of saponification, the better the oxygen barrier performance.

[0031] The first polymer composition may comprise at least one of the following:

[0032] - polyvinyl alcohol obtained, for example, by saponification of polyvinyl ester homopolymers or copolymers,

[0033] - ethylene vinyl alcohol copolymer (EVOH),

[0034] -Butylene glycol-vinyl alcohol copolymer (BVOH).

[0035] In some embodiments, the maximum water content of the first polymer composition is 10%. In particular, in embodiments containing salt, the water content may be no more than 5%, in particular no more than 1% or no more than 0.5%.

[0036] The first class polymer composition may also include a plasticizer (liquid or solid) to reduce the melting temperature, which is particularly beneficial for molding. In certain embodiments, the plasticizer may be hygroscopic. The plasticizer may be selected from the group consisting of polyols (oligonucleotides and polyols) and low molecular weight amides, especially triols, diols, polytriols, polyglycols, such as glycerol, ethylene glycol, propylene glycol, triethylene glycol, low molecular weight polyethylene glycol; and low molecular weight amides. In certain embodiments, the plasticizer may be selected from the group consisting of higher oligomers of dipropylene glycol, ethylene glycol or propylene glycol, butanediol, glycerol, pentaerythritol, sorbitol, 1,4-monoanhydrohexitol, 1,4-3,6-dianhydrohexitol and their esters. Preferred plasticizers are glycerol and polypropylene glycol.

[0037] The content of plasticizer may be between 2% and 25%, in particular between 5% and 18%, for example between 10% and 15%.

[0038] Embodiments of the first class of polymer compositions in the examples may particularly include more salt than plasticizer. More specifically, the ratio of salt to plasticizer may be between 1.5:1 and 6:1.

[0039] It is not excluded that the first type of polymer composition, in addition to the water-soluble polymer, possibly the salt and optionally the plasticizer, also contains further ingredients, such as heat stabilizers (e.g. metal stearates such as sodium stearate), for example in a concentration of up to 1%, in particular up to 0.5%, and / or inorganic fillers and / or organic fillers, such as cellulose or fillers as described in WO 2021 / 224424 and / or other ingredients that affect the properties of the composition or its components.

[0040] Examples of suitable polymer compositions of the first type can be found, for example, in WO 2014 / 155059.

[0041] As an alternative to the composition described in WO 2014 / 155059, the first polymer composition may contain, in addition to the polymer ("resin", such as polyvinyl alcohol, ethylene-vinyl alcohol copolymer (EVOH) or butene glycol-vinyl alcohol copolymer (BVOH)) and plasticizer (but not necessarily salt) additives, in particular saturated fatty acids, binders and / or antioxidants. These additives have been shown to be beneficial to the properties of the first polymer composition, in particular with regard to suitability for molding processes and biodegradability.

[0042] Other ingredients of the first type of polymer composition may include water (e.g. between 1% and 10%, especially between 2% and 6%), and additives comprising 0% or 1% to 5% or 3% fatty acids, binders (e.g. 0% or 1% to 5% or 3%), and / or antioxidants (in an amount of, for example, less than 0.5%, especially between 0.1% and 0.3%).

[0043] Another example of a suitable first polymer composition comprises 70% to 85% polyvinyl alcohol (e.g. 98% degree of hydrolysis), 10% to 15% glycerol as a plasticizer, 2% to 6% water, and 1% to 3% saturated fatty acids, 1% to 3% binders and 0.1% to 0.3% additives in the form of antioxidants.

[0044] In addition to (or as an alternative to) including one or more first polymer compositions, the valve may also include components of a second polymer composition. Like the first polymer composition, the second polymer composition may also be biodegradable, according to the definition used above. However, the second polymer composition is not soluble in water, and in embodiments they do not contain salts.

[0045] Examples of the second class of polymer compositions have one or more polymers selected from the group consisting of:

[0046] - Polyhydroxybutyrate (PHB),

[0047] - Polyhydroxyalkanoates (PHAs), other polyesters

[0048] -Polyester, (PHB is polyester)

[0049] - aliphatic polyesters,

[0050] - Poly-4-hydroxybutyrate (P4HB),

[0051] - Polyhydroxyvalerate (PHV),

[0052] - polyhydroxycaproate (PHH), and

[0053] -Polyhydroxyoctanoate (PHO)

[0054] Embodiments of the second type of polymer composition may also have plasticizers and / or other ingredients, such as organic fillers.

[0055] The valve membrane may be made of the second polymer composition. In particular, it may be preferred that the valve membrane is insoluble in water.

[0056] The second type of polymer composition may be steam resistant.

[0057] In contrast, in an embodiment, the main body is a first type of polymer composition. Alternatively, the main body may also be a second type of polymer composition.

[0058] If present, the fixing component may be of the first polymer composition. For example, the fixing component may be of the same polymer composition as the body. There is also an alternative for the fixing component where the component may be of the second polymer composition.

[0059] If present, the permeable membrane may be of the first polymer composition.The permeable membrane may be of the same composition as the body, although in embodiments the composition may be different, for example, the permeable membrane contains a higher proportion of plasticizer than the body.

[0060] The body may include an oil distribution groove. An oil distribution groove is a shallow indentation in the surface area of ​​the body against which the valve diaphragm rests. The oil distribution groove is used to contain excess sealing fluid and act as a reservoir for it. An oil distribution groove is beneficial and often necessary to ensure that the space between the valve diaphragm and the surface against which it rests is always evenly supplied with sealing fluid.

[0061] In one set of embodiments, the bottom of the body has at least one outer oil distribution groove including a radial extension. The outer oil distribution groove is a groove located radially outside the bottom, i.e. at a radial distance from the at least one through hole. In particular, the outer oil distribution groove may be closer to the circumferential wall than to the center of the bottom.

[0062] The outer sump or the outer sump system, besides extending radially, usually extends in the circumferential direction, for example with its main part parallel to the circumferential wall (parallel means that the normal distance is constant).

[0063] The radially extending portion is a portion of the oil distribution groove that extends radially from a main portion of the oil distribution groove.

[0064] The radial extension has the advantage, depending on its size, of reducing the adhesion of the membrane, thereby making it possible to control the adhesion of the membrane.

[0065] The background is as follows: For a certain size of pressure relief valve and its valve diaphragm, the adhesion between the body and the valve diaphragm may be too high for certain applications. For example, in some cases, if a large amount of gas escapes after the valve diaphragm is lifted (for example in the case of relatively large packages), the pressure required to lift the valve diaphragm may become too high and the return of the valve to the closed state may be more unpredictable. However, for other packages, a fairly high adhesion force is required to ensure sufficient sealing. This can in principle be solved by manufacturing valves of different sizes. However, if different valve sizes need to be provided for different types of packages, the manufacturing process becomes more complicated. Another prior art method is to use sealing liquids of different compositions depending on the required adhesion. However, it is a challenge to fine-tune the adhesion by changing the chemical composition without sacrificing other properties - especially if the materials of the valve diaphragm and the body are selected with other properties in mind and there is no freedom to adjust these properties.

[0066] The method of using radial extensions enables all packages to use bodies and valve membranes of standard size and sealing fluids with a higher tendency to adhere. Due to the extensions, the effective length of the path for the valve membrane to adhere to the body surface is reduced. Therefore, the adhesion forces to be overcome by the pressure rise in the package until the valve is actuated are also reduced, and the greater the radial extension, the greater the reduction in adhesion forces to be overcome. Therefore, in order to adapt the valve to different applications requiring different actuation pressures / triggering pressures, only one parameter needs to be changed, namely the size of the radial extension (radial dimension).

[0067] The radial extension may in particular be an inward extension.

[0068] In one set of embodiments, the body comprises a plurality of outer oil distribution grooves. For example, the outer oil distribution grooves may comprise an annular array of at least two outer oil distribution grooves, which together form a (interrupted) ring.

[0069] In particular, the outer oil sump may include an annular array of first outer oil sumps and an annular array of second outer oil sumps, the first outer oil sumps being arranged around the second outer oil sumps. In such a configuration, the second outer oil sumps may be staggered relative to the first outer oil sumps, such that the second outer oil sumps cover the gaps between the first outer oil sumps, whereby there is no radial line from the center of the bottom to its periphery (to the peripheral wall) that is not interrupted by the outer oil sump.

[0070] In the embodiment where the outer oil distribution grooves are arranged in at least one annular array, each oil distribution groove may have one inward extension. If there are multiple annular arrays, it is sufficient that each oil distribution groove of one array has one inward extension.

[0071] In an embodiment with two circular oil distribution groove arrays, the radially inward extensions may be inward extensions of the first outer oil distribution grooves. They may extend through the gaps between the second outer oil distribution grooves, optionally extending to a position radially inward of the second outer oil distribution groove positions.

[0072] In addition to the above-mentioned function of adjusting the adhesion, the radial extension can also balance the distribution of the sealing liquid between the first and second oil distribution grooves.

[0073] The main body may include an extended accommodating groove inside the peripheral wall in a plane defined by the valve membrane. The extended accommodating groove provides a space into which the valve membrane can expand so that the valve membrane will not bulge when expanding, for example, when the valve membrane is wet.

[0074] The surface portion of the body against which the valve diaphragm rests can be flat, rather than the curved (arched) surface portion of prior art valves. Such a flat structure can be beneficial, in particular when the valve diaphragm and / or the body are made of biodegradable materials, because the adhesion will not change when the properties of the material, such as elasticity, change slightly due to absorption of moisture or aging. The flat structure is particularly beneficial together with the extended adaptation groove, because this combination allows the precise placement of the valve diaphragm (by adapting the diameter to the inner diameter of the cup-shaped body) without the risk of the membrane becoming arched or otherwise deformed when expanded.

[0075] In one set of embodiments, in particular if the valve has a permeable membrane, the body has at least one notch on the product side, thereby 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 on the product side. This means that if there is a permeable membrane, the through hole opening is offset relative to the plane of the permeable membrane. This is particularly beneficial if both the permeable membrane and the body contain water-soluble polymers, such as made of a first class polymer composition. That is, packaged food products often contain residual moisture even if they are dry. This is the case, for example, with roasted coffee (ground or bean-shaped). This residual moisture may cause the water-soluble polymer to absorb some moisture and thus become sticky. This tendency may increase in the first class polymer composition due to the salt content. However, if the permeable membrane is attached to the body, ventilation in the "horizontal" direction (direction parallel to the plane defined by the bottom of the body) between the permeable membrane and the body will be hindered. Therefore, the gas can only diffuse through a small area with a through hole diameter on the permeable membrane. This may be unsatisfactory because such a small area may be susceptible to blockage and the like. The method of arranging the through holes in the recessed parts solves this problem. The recessed parts can effectively form a system of venting grooves with spacers between them.

[0076] In an embodiment, the spacer has rounded edges.Thereby, when the package is subjected to mechanical stress, there is less risk of damaging the permeable membrane.

[0077] In addition to being related to a pressure reducing valve, the present invention also relates to a packaging, in particular a coffee bag for coffee beans or ground coffee. The packaging comprises a flexible, pliable packaging material and a pressure reducing valve as described herein. The body of the pressure reducing valve is attached to the packaging material. In particular, the annular end face of the pressure reducing valve can be attached to the packaging material, wherein the valve diaphragm (and, if present, the fixing member) is arranged in a cavity between the bottom of the body and the packaging material. The packaging material is usually airtight, but has an opening or other permeable structure at a position surrounded by the peripheral wall of the body. BRIEF DESCRIPTION OF THE DRAWINGS

[0078] The embodiments of the present invention are described below in conjunction with the accompanying drawings. In the accompanying drawings, the same numbers represent the same or corresponding elements. The accompanying drawings show:

[0079] Figure 1 Exploded view of the pressure reducing valve assembly;

[0080] Figure 2 The subject's view;

[0081] Figure 3 a cutaway view of the assembled valve;

[0082] Figure 4 different views of the subject;

[0083] Figure 5 Another view of the subject;

[0084] Figure 6 another view of the assembled valve in section; and

[0085] Figure 7 The valve in the package is shown schematically. DETAILED DESCRIPTION

[0086] Figure 1 , 3 The pressure reducing valve shown in FIG. 6 includes a main body 1, which is also shown in FIG. Figure 2 , 4 and 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.

[0087] The peripheral wall 12 surrounds the sealing surface of the bottom 11 and has a flange 13, i.e. a shoulder protruding outward, at its end opposite the bottom 11, so that the annular end face 16 with the energy guiding ribs 18 on the packaging side is wider. The bottom has at least one through hole 14 (three through holes 14 in the described embodiment), which is covered by the valve membrane 2 that is attached to the sealing surface of the bottom 11. There is a thin layer of sealing liquid, especially oil, such as silicone oil, between the bottom 11 and the valve membrane 2. As is known, silicone oil is used for this purpose. Therefore, the sealing liquid is not described in detail in this article.

[0088] The pressure relief valve for this purpose is placed in a gas-tight flexible package, wherein the annular end face 11 of the peripheral wall is bonded to the inner surface of the package by welding or the like. The packaging material has at least one gas channel (e.g. at least one small through hole or permeable portion) at the position surrounded by the annular end face. If there is an overpressure in the package, the gas will cause the valve membrane 2 to rise from the bottom 12, thereby forming a gas channel. Excess gas can then escape through the through hole 14, between the valve membrane and the bottom and through the gas channel of the package. When there is no overpressure in the package, the valve membrane closes the package by resting against the bottom, and the sealing liquid adheres to the bottom and the valve membrane by capillary forces to form a seal.

[0089] The body 1 comprises, inside the peripheral wall 12 and in the plane defined by the valve membrane 2, an extended adaptation groove 41. It has been found that such a groove 41 is beneficial for the following reasons: the valve membrane 2 can be composed of a biodegradable polymer. It has been found that these materials may tend to change size depending on environmental conditions compared to the valve membrane materials of the prior art. For example, if they are exposed to moisture, they may swell slightly.

[0090] In an embodiment, the pressure reducing valve has a permeable membrane 3 in addition to the body 1 and the valve membrane 2. The permeable membrane 3 is gas permeable compared to the valve membrane 2. For example, it can be a fabric, such as a non-woven fabric. The permeable membrane is connected to the surface of the product side of the bottom and covers at least the through hole 14. If the package contains fine-grained products, especially ground coffee, the permeable membrane is useful because it prevents the product from clogging the opening and preventing contact with the sealing liquid and the valve membrane 2. It is not necessary for packaging containing, for example, coffee beans or other large-grained products.

[0091] 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 the main body. For this reason, the main body has a product-side energy guiding rib 38 on the side facing the packaged product.

[0092] On the sealing surface side, the body has a plurality of oil distribution grooves. More specifically, the body has an inner oil distribution groove 21 surrounding the opening, and further has a circle of three first outer oil distribution grooves 22 and a circle of three second outer oil distribution grooves 23, the first outer oil distribution grooves 23 being arranged around the second outer oil distribution grooves 22. The outer oil distribution grooves 22, 23 generally extend in the circumferential direction, each having a main portion 27 extending in the circumferential direction and parallel to the peripheral wall. Each second outer oil distribution groove 23 has an outward extension 24 extending radially outward from the main portion 27 into the gaps between the first outer oil distribution grooves 22. The first outer oil distribution grooves 22 each have an inward extension 25 extending radially inward from the main portion 27 into the gaps between the second outer oil distribution grooves 23 and even further radially inward.

[0093] In this context, "radial" as well as "outwardly" or "inwardly" or "circumferentially" are referenced to the axis 10 of the body; the presence of a central axis does not necessarily imply axisymmetry, although such symmetry is an option.

[0094] The outer oil grooves have the function of serving as sealing liquid reservoirs. For this purpose, they are located in a radial position so as to be covered by the valve diaphragm (see e.g. Figure 3 or Figure 6 ). For example, when the valve is subjected to temporary mechanical loads (e.g. during transport of the valve before it is glued to the package or during transport of the package with the valve), the sealing liquid can be forced out from between the bottom 11 and the valve membrane 2. The oil distribution groove ensures that capillary forces can then suck the sealing liquid out of the oil distribution groove under the valve membrane again. Similar factors are taken into account during the manufacturing process: due to the presence of the oil distribution groove, it is sufficient to drip a drop of sealing liquid onto the bottom or the membrane, and the oil distribution groove ensures that the sealing liquid is well distributed and the sealing membrane adheres evenly to the bottom around the through hole 14.

[0095] In addition to this well-known function, the special structure of the outer oil grooves 22, 23 makes it possible to better control the adhesion forces. That is, the distance between the inner oil groove 21 and the outer oil grooves 22, 23 defines the minimum length p1 of a path along which the adhesion forces must be overcome in order to trigger the valve by lifting the valve membrane 2 from the bottom 11. If there were no inner oil grooves, the quantity of interest would be the distance between the through hole 14 and the inward extension 25.

[0096] like Figure 5 As shown, the path length p1 can be controlled by selecting the length of the inwardly extending portion 25 .

[0097] The outward extension 24 and the inward extension 25 both have the further function of distributing the sealing liquid between the oil distribution grooves. For example, due to the presence of the outward extension 24 and the inward extension 25, the sealing liquid can be communicated between the first outer oil distribution groove and the second outer oil distribution groove, and between different first oil distribution grooves and different second oil distribution grooves.

[0098] The system comprises 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 the arrangement in which the oil distribution grooves are uninterrupted rings, the system has the following advantages: the sealing liquid can be well distributed along the edge of the bottom 11 even when the valve remains in a constant vertical orientation for a long time.

[0099] In the embodiment, the pressure reducing valve has a fixing part 4 in addition to the body 1 and the valve diaphragm 2 and, if applicable, the permeable membrane 2. The fixing part 4 is optional and can be used 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 shock. In the embodiment shown, the fixing part 4 is a star with three spoke ribs. It has a first distance-keeping rib 51 and a second distance-keeping rib 52. The overall star shape and the distance-keeping ribs 51, 52 constitute a shape that saves material but has a stable orientation. In addition, the star shape ensures some elasticity of the fixing part 4.

[0100] For example, Figure 6 As shown, the shape of the peripheral wall 12 forms a slight undercut 42 inside, and the inner surface of the main body is slightly conical. Due to this undercut shape, the fixing component 4 can be snapped into the main body and is kept there due to its elasticity.

[0101] On the side facing the product, the body 1 is constructed to include a venting groove system 31 and a spacer 33. This system enables the through hole 14 to be located at the bottom of the venting groove, i.e. where the surface on the product side is recessed. The radial channels 32 of the venting groove system 31 ensure that the gas diffused into the venting channel through the gas-permeable membrane can reach the through hole 14. As a result, the gas encounters less resistance and can diffuse through a relatively large surface portion, because the membrane is not pressed against a flat surface due to the overpressure in the package. On the contrary, the spacer 33 keeps it away from the plane where the through hole 14 opens.

[0102] Another effect of the vent groove system is to prevent the gas permeable membrane 3 from adhering to the main body in the area around the through hole 14. Such adhering may occur during the bonding of the gas permeable membrane 3 to the main body, for example by ultrasonic welding.

[0103] For example, Figure 5 As shown, the spacer 33 has rounded edges 35 so that there is less risk of damaging the permeable membrane when the package is subjected to mechanical stress.

[0104] The overall shape of the body with the flange 13 and the widened end face 16 (which is bonded to the packaging material) further improves the process of bonding the valve to the packaging material and the stability of the bonding. That is, the shoulder defined by the flange as an outwardly protruding shoulder forms a coupling-in surface 17, on which the tool for bonding the valve to the packaging material can directly act. Therefore, the energy (usually ultrasonic energy) coupled into the body 1 by the tool for the bonding process does not need 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 the case where the tool presses on the end face of the body on the product side.

[0105] The tool can be, for example, a tubular sonotrode, the tube diameter of which corresponds approximately to the diameter of the flange 13 .

[0106] However, the flange 13 and the widened end face 16 are only optional. In alternative embodiments, the body 1 does not have such a structure. In these alternative embodiments, the body 1 can also be welded to the packaging material by applying a sonotrode to the end face of the body on the product side. Also in these embodiments, the sonotrode used can optionally be tubular, with a tube diameter greater than the outer diameter of the area with the venting groove system and the spacer. However, alternatively, the sonotrode can have a flat outcoupling input face.

[0107] In the embodiment, the main body 1, the fixing member 4 and the permeable membrane 3 are all made of a polymer composition, which includes a water-soluble polymer and, for example, also includes a salt:

[0108] - The body 1 and the fixing part 4 are injection molded from a polymer composition comprising PVOH obtained by, for example, saponification of polyvinyl ester (Poly (vinyl ester)), a salt (especially sodium chloride) and glycerol. In an alternative embodiment, the body 1 and the fixing part 4 are injection molded from a polymer composition comprising PVOH obtained by, for example, saponification of polyvinyl ester (Poly (vinyl ester)), for example 98% hydrolyzed, 10% to 15% glycerol as a plasticizer, 2% to 6% water, and additives in the form of 1% to 3% saturated fatty acids, 1% to 3% adhesives and 0.1% to 0.3% antioxidants. The polymer composition of the body and the fixing part can be the same.

[0109] The permeable membrane is a fibrous fabric made of a polymer composition, also comprising PVOH obtained, for example, by saponification of polyvinyl ester, a salt (especially sodium chloride) and glycerol.

[0110] The valve diaphragm 2 is made of PHB material.

[0111] All components are therefore biodegradable.

[0112] Figure 7 A package with a valve is schematically shown, in which a main body 1 is welded to a packaging material 60, and a through hole 61 is provided in the packaging material for releasing gas.

Claims

1. A pressure reducing valve, comprising: A body (1) configured to be fixed to a flexible packaging material, the body having at least one through hole (14) forming a passage through the body; a valve membrane (2) abutting against the body from the packaging side in an area around the at least one through hole (14); and a sealing liquid between the body (1) and the valve membrane (2), characterized in that at least one component of the valve is made of a polymer composition including a water-soluble polymer.

2. The valve of claim 1, wherein the polymer composition of at least one component comprises a salt.

3. The valve according to claim 1 or 2, wherein at least the body is made of a polymer composition comprising a water-soluble polymer and a salt.

4. A valve according to any one of the preceding claims, wherein the water-soluble polymer comprises a polymer chain having a plurality of vinyl alcohol groups, wherein the water-soluble polymer is, for example, polyvinyl alcohol (PVOH).

5. Valve according to any of the preceding claims, wherein the valve membrane (2) is made of a material that is insoluble in water.

6. A valve according to any one of the preceding claims, consisting of a biodegradable material.

7. Valve according to any one of the preceding claims, further comprising a permeable membrane (3) fixed to the body (1) to cover the at least one through hole (14) at the product side opposite to the packaging side.

8. Valve according to any of the preceding claims, wherein the permeable membrane (3) is a fabric made of a polymer composition comprising a water-soluble polymer.

9. Valve according to any of the preceding claims, wherein at least one through hole (14) or the opening of a through hole (14) on the product side is offset relative to an outermost plane defined by a surface of the body on the product side.

10. Valve according to claim 9, wherein the body has a system of ventilation grooves with spacers between them, at least one through hole (14) or the opening of a through hole (14) being located in a ventilation groove.

11. A valve according to any one of the preceding claims, wherein the main body (1) is cup-shaped, having a bottom (11) and a peripheral wall (12), and the valve further comprises a fixing part (4) fixed relative to the peripheral wall, so that the valve diaphragm (2) is clamped between the bottom (11) and the fixing part (4).

12. A valve according to any one of the preceding claims, wherein the main body (1) is cup-shaped, having a bottom (11) and a peripheral wall (12), and wherein the bottom (11) has an oil distribution groove system on the packaging side for accommodating a portion of the sealing liquid, the oil distribution groove system comprising at least one outer oil distribution groove (22, 23), the outer oil distribution groove having a main part (27) extending in the circumferential direction and having a radially inward extension (24, 25) extending from the main part (27) to a radially inward direction.

13. The valve according to claim 12, wherein: The oil distribution tank system comprises at least one annular array having at least two first outer oil distribution tanks (22) and at least one annular array having at least two second outer oil distribution tanks (23), wherein the first outer oil distribution tanks (22) are arranged around the second outer oil distribution tanks (23), and the second outer oil distribution tanks are staggered relative to the first outer oil distribution tanks.

14. The valve according to claim 12 or 13, wherein the oil distribution groove system further comprises an inner oil distribution groove (21) extending around the at least one through hole (14).

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

Images