Pressure Relief Valve with High Pressure Opening and Closing Functionality

FIELD

This invention relates generally to one-way pressure relief valves of the type that may be applied to flexible-walled product packaging, and more particularly, to pressure relief valves engineered to maintain the three-dimensional appearance of the package under conditions of increasing or decreasing ambient pressure.

BACKGROUND

A challenge facing producers of packaged goods, such as roasted coffee, food products, personal care products, and other types of products is the important need for the package in which the goods are provided to retain its three-dimensional appearance from the point of packaging to the point of sale, for example sale in a retail store setting. It is important to the perception that the packaged goods are of the highest quality that the three-dimensional appearance of the package be as close as possible to the appearance of the package at the point of packaging with neither undue expansion nor contraction of the package. A consumer may perceive that an excessively expanded or contracted package may contain goods that are defective in some way. And, excessive expansion or contraction could cause failure of the package such as rupture or tearing of a film-type freshness or safety seal frequently provided as a closure over an opening of the package.

Retention of the three-dimensional appearance of the package is of particular importance when the package is of materials which have properties of flexibility. Packages with flexible walls can include, for example, canister-type packages and bag-type packages of the types routinely used to package goods such as roasted coffee in ground or bean form. Such flexible-walled packages may be made of many different materials including, for example, polymeric materials, cellulosic materials, and metallic materials.

Package expansion can be of particular concern with respect to packaged roasted coffee. As is known, roasted coffee in bean or ground form is most flavorful when packaged immediately following the production process. However, and as is also known, roasted coffee produces large volumetric amounts of gas, including carbon dioxide gas. Accumulation of gas produced by the coffee within the package causes an increase in pressure within the package relative to ambient pressure outside the package such that flexible-walled packages may deform by expansion taking on a swollen and potentially unattractive appearance.

Pressure relief valves have been developed to relieve excess gas pressure from within the package. Pressure relief valves may be attached to the package over a small opening or openings in the package. The pressure relief valve opens to release excess pressure from within the package and closes once the pressure has been relieved, thereby retaining the three-dimensional appearance of the package or at least minimizing expansion of the flexible-walled package. Pressure relief valves of the types just described may allow gas flow in just one direction, namely, out of the package. Such pressure relief valves are characterized as one-way pressure relief valves because they both relieve pressure from within the package while also blocking entry of ambient air into the package. Ambient air must be kept out of the package to prevent oxidation damage to goods such as ground coffee, thereby preserving the fresh and delicious taste of the coffee.

Yet another challenge confronting the packager is the potential for contraction of the package. Package contraction is referred to by some in the packaging field as “paneling.” Paneling means or refers to a collapsed or compressed appearance of the package which presents a sort of deformation of the package as compared to the original three-dimensional shape at the point of packaging. Paneling can occur when pressure within the package becomes relatively less than ambient pressure outside the package causing the flexible-walled package to collapse or panel. Any unwanted contraction of the package walls could create the perception that the packaged goods are themselves defective.

In addition to the foregoing problems, excessive package expansion or contraction can cause failure of films used routinely as freshness and safety seals for packages containing consumer goods such as roasted coffee. More specifically, forces resulting from expansion or contraction of the package can stress the joint where the aforementioned film seals are joined to the package walls, for example by heat sealing. The forces can cause failure of the joint resulting in small openings between the film and package walls. Any failure of the joint could allow unwanted ambient air and oxygen to enter the package through the openings, potentially spoiling the packaged goods and rendering the goods unsalable.

FIG. 1 illustrates several scenarios wherein a canister-type package 5 with flexible walls can be subjected to states of expansion, and alternatively, contraction between the point of packaging and the point of retail sale. Such expansion and contraction may be caused by changes in ambient pressure which can occur between the point of packaging and the point of sale.

In the first scenario of FIG. 1, a first location 1 is shown at which a coffee packager 3 roasts and loads roasted coffee into packages such as canister-type package 5. In the example, package 5 has flexible package walls 7 which may be made of any suitable type of material such as polymeric or cellulosic materials. In the example of FIG. 1, pressure relief valve 9 is affixed to a top wall 8 of package 5. Valve 9 may be located on package 5 at positions other than top wall 8, for example on a wall 7. In the first scenario of FIG. 1, first location 1 is at a relatively high elevation of 5,000′ mean sea level (MSL). After packaging, it would be expected that package 5 would initially have an appearance and three-dimensional shape with no deformation because pressure within package 5 would be approximately the same as ambient pressure at first location 1. Referring to FIG. 3B, the broken lines 10 in the plan views illustrate an approximate position of package 5 walls 7 in this original and non-deformed state. Inclusion of pressure relief valve 9 would help minimize expansion of package 5 caused by coffee-generated gas by allowing excessive volumetric amounts of gas within package 5 to be released.

In the second scenario of FIG. 1, canister-type package 5 may be transported by truck 11 to a second location 13 which is at an MSL elevation greater than the first location 1. In the example, package 5 may be transported by truck 11 along a route through mountainous 15 elevated terrain to second location 13 at, for example, 10,000 MSL. At second location 13 it would be expected that ambient pressure would be lower than ambient pressure at first location 1 where the coffee was packaged by packager 3.

As a consequence of the relatively lower ambient pressure at second location 13, it would also be expected that the pressure within package 5 would be relatively greater than ambient pressure as compared with pressure within package 5 at first location 1. Production of gas by the coffee within package 5 would further increase relative pressure within package 5 at second location 13. As a result of the decrease in ambient pressure at second location 13 and gas produced by the packaged coffee, package 5 may take on an expanded or swollen appearance shown in the second scenario of FIG. 1 and in FIGS. 2A-2B wherein package walls 7 are bulged outwardly stretching and tensioning the package 5 material. Package 5 would be expected to have a swollen appearance in the second scenario even if provided with pressure relief valve 9 because of the combination of the lower relative ambient pressure outside the package 5 and the production of gas within the package 5. Package 5 would be inclined to expand even if the goods were of a type that does not produce gas because of the lower ambient pressure at the elevation of second location 13. Excessive expansion could cause package failure or a rupture of the safety or freshness seal.

In the third scenario of FIG. 1, package 5 is shown after further transportation by truck 11 along a route from second location 13 to a third location 17. Third location 17 may, for example, be a destination such as a retail store where package 5 may be placed on display on a store shelf for purchase by a consumer. The appearance of package 5 is important to consumers making a purchasing decision at third location 17. What is wanted is that package 5 have a three-dimensional appearance which is identical to that when the coffee was originally packaged by coffee packager 3 at first location 1.

In the example, third location 17 may be at sea level (i.e., 0 MSL) represented schematically by ocean water 19 where it would be expected that ambient pressure would be greater than at both the first and second locations 1, 13. As a consequence of the relatively greater ambient pressure at third location 17, it would be expected that pressure within package 5 would be relatively less than ambient pressure as compared with pressure within package 5 at first and second locations 1, 13. As a result of the relative increase in ambient pressure at third location 17, package 5 may have an appearance which is contracted or “paneled” like that illustrated in the third scenario of FIG. 1 and FIGS. 3A-3B where walls 7 appear to be pressed inwardly. The contraction of walls 7 is represented by the wavy lines illustrated on wall 7 in FIG. 3A. Paneling of the type illustrated in FIGS. 1 and 3A-3B results in an aesthetically unappealing package 5 with an appearance which appears to be wrinkled, distorted, or badly puckered, and/or with a ruptured safety or freshness seal.

While expansion and contraction caused by changes in ambient pressure has been described, it should also be noted that package 5 expansion and contraction can be caused by other forces. For example, increases or decreases in ambient temperature can cause package 5 expansion and contraction.

For non-gas-producing products, paneling can be a particular problem when the packaged product is transported to a location at a much lower altitude than the location at which the product was packaged. For gas-producing products like coffee, the effect of changes in altitude and resultant paneling could be expected to be lessened because the gas produced by the coffee would serve to offset any external pressure increase. However, if the coffee was producing minimal volumes of gas or not producing gas at all (referred to by some as “dead” coffee), then the pressure differential could be such as to cause noticeable paneling of the coffee-containing package 5.

A problem confronting packagers of products such as ground coffee is that conventional pressure relief valves 9 can actually contribute to package deformation and paneling in scenarios like those described in connection with FIG. 1 where the packaged product is subjected to meaningful changes in ambient pressure. This is because pressure relief valves of the type illustrated by reference number 9 open to relieve high relative pressure within the package but are not capable of closing at high relative pressure within package 5 to preserve gas pressure within package 5 that would offset increases in ambient pressure which causes paneling. Put another way, once opened, the pressure relief valves 9 stay open until pressure within package 5 is approximately equalized (i.e., about the same as) ambient pressure at which point the pressure relief valves 9 close. If the packaged coffee is unable to generate sufficient gas to offset any increase in ambient pressure, then package 5 can take on the paneled appearance illustrated in FIGS. 3A-3B responsive to the increase in the ambient pressure. Thus, existent pressure relief valves 9 lack the capability to both open and close when pressure within package 5 is relatively high. Accordingly, existent valves 9 are not optimally able to maintain package 5 appearance responsive to both material increases and, alternatively, decreases in ambient pressure relative to pressure within package 5.

It would be an improvement in the art to provide a one-way pressure relief valve which can both relieve pressure from within a package to minimize or avoid package expansion and which can maintain sufficient pressure within the same package to offset increases in ambient pressure to minimize or avoid package contraction or paneling to thereby preserve the quality of the packaged goods and fairly promote the perception that the goods within the package are of the highest quality.

SUMMARY

The present invention relates to improved one-way pressure relief valves with structure providing high pressure opening and closing functionality. Pressure relief valves of the types described herein may be associated with the packaging used to contain consumer products. Pressure relief valves of the types described herein have particular utility when used with packaging for gas-producing goods such as dry roasted coffee in ground or bean form. The pressure relief valves are effective to allow escape of gas from within the package while also blocking entrance of ambient air into the package potentially damaging goods within the package. When used with packages having flexible walls, valves of the types described herein are effective to avoid or minimize undue expansion or swelling of the package.

Valves as described herein are also effective to avoid or minimize collapse or “paneling” of flexible-walled packages. As explained, this type of package deformation can occur when ambient pressure is relatively greater than pressure within the package such as when the goods are packaged at a location with an ambient pressure greater than a location to which the goods are transported.

These desirable results are accomplished by means of pressure relief valves with structure providing both high pressure opening and closing functionality. Valves of the types described herein open when pressure within the package is at a pressure relatively greater than ambient pressure. Importantly, such valves are capable of closing while pressure within the package remains high relative to ambient pressure. Such closure retains pressure within the package to thereby resist collapse of the package responsive to high relative ambient pressure. The result is to provide for a flexible-walled package which appears aesthetically attractive with control of package deformation while also preserving the quality of the packaged product.

In embodiments, a high-pressure pressure relief valve according to the invention may include a base layer, a cover layer, and a dry strap between the base and cover layers. As used herein, the base and cover layers may be referred to simply as base and cover. A base layer may define a plane and have a first side, a second side, an area, and a peripheral edge. A base layer may further define a vent extending entirely through the base.

The cover layer may overlie the base layer and have cover layer first and second sides, a width dimension, an area, a peripheral edge generally co-extensive with the base peripheral edge, and a thickness dimension. The thickness dimension of the cover layer may be about 0.001 inch to about 0.020 inch between the first and second sides. The cover layer may also have a pair of attachment regions secured to the base layer at spaced apart locations of the cover layer.

The dry strap may entirely overlie the vent between the base layer, the cover layer, and the attachment regions of the cover layer. A dry strap may have a first side, a second side, an area, a thickness dimension of about 0.0005 inch to about 0.002 inch between the first and second sides, a width dimension less than the width dimension of the cover layer thereby enabling location of the dry strap between the attachment regions, and a length dimension extending from one peripheral edge portion of the cover layer to proximate an opposite peripheral edge portion of the cover layer.

A wetting fluid may be disposed between the dry strap and the first side of the base layer. A wetting fluid is useful to improve closure of the vent by the dry strap.

The cover layer, dry strap and other components provide a valve which both opens and closes at high relative pressure inside the package to which the valve is attached. In embodiments, the valve opens when pressure inside the package exceeds ambient pressure by about 0.725 psig to about 1.450 psig and the valve closes when pressure inside the package exceeds ambient pressure by about 0.145 psig to about 0.725 psig. In embodiments, these opening and closing pressure ranges may be achieved by selection of one or more of a cover thickness, a dry strap thickness, and a dry strap width and also with influence from other valve structure as described herein. The novel opening and closing pressure capabilities of the valve allows excess pressure within the package to be relieved while retaining sufficient pressure within the package to limit paneling of the package responsive to an increase in ambient pressure relative to the pressure within the package.

Other features and embodiments are described in the drawings and detailed description which follows.

BRIEF DESCRIPTION OF THE DRAWINGS

Examples of pressure relief valves with high pressure opening and closing functionality may be understood by reference to the following description taken in conjunction with the accompanying drawings, in which like reference numerals identify like elements throughout the different views. For convenience and brevity, like reference numbers are used for like parts amongst the embodiments. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention.

In the accompanying drawings:

FIG. 1 is a schematic drawing illustrating the effect of changes in ambient pressure on a flexible-walled package containing product in the form of roasted coffee;

FIGS. 2A-2B are enlarged perspective and top plan views of the package of FIG. 1 in an enlarged state;

FIGS. 3A-3B are enlarged perspective and top plan views of the package of FIG. 1 in a contracted state;

FIG. 4 illustrates a flexible-walled package including a pressure relief valve with high pressure opening and closing functionality according to the invention;

FIG. 5 is a further illustration of the package and pressure relief valve of FIG. 4;

FIG. 6 illustrates a pillow bag package including a pressure relief valve with high pressure opening and closing functionality according to the invention;

FIG. 7 is a section view taken along section 7-7 of FIG. 4 showing the pressure relief valve in a closed state;

FIG. 8 is a section view taken along section 7-7 of FIG. 4 but showing the pressure relief valve in an exaggerated open state;

FIG. 9 is an enlarged section view of the pressure relief valve of FIG. 7 apart from the package and in a closed state;

FIG. 10 is an enlarged section view of the pressure relief valve of FIG. 9 apart from the package in an exaggerated open state;

FIG. 11 is a plan view of an embodiment of a pressure relief valve with high pressure opening and closing functionality according to the invention in an open state with certain internal features shown to facilitate understanding;

FIG. 12 is a perspective view of the pressure relief valve of FIG. 11 in an exaggerated open state with certain internal features shown to facilitate understanding;

FIG. 13 is an exploded view of the pressure relief valve of FIGS. 4-10;

FIG. 14 is an exploded view of a further embodiment of a pressure relief valve with high pressure opening and closing functionality according to the invention including a single-opening vent;

FIG. 15 is a plan view of four pressure relief valves of the type illustrated in FIGS. 4-10 and 13 arranged on a release liner.

FIG. 16 is a graph comparing opening and closing pressure characteristics of inventive and control valves; and

FIG. 17 is a graph comparing opening and closing pressure characteristics of further inventive valves with a control valve.

DETAILED DESCRIPTION

The present invention relates to improved one-way pressure relief valves with high pressure opening and closing functionality, embodiments of which are indicated by reference numbers 110 and 110a in FIGS. 4-15. Throughout this patent application, certain components of exemplary valves 110, 110a may be alike and, for convenience and brevity, such components are discussed concurrently and have like reference numbers. Valves 110, 110a of the types described herein may be used with a range of package types with flexible walls and/or panels including canister-type packages 111, and pillow bag-type packages 111a and would serve as a substitute for valve 9 on package 5 of FIGS. 1-3B. Package 111, 111a walls and/or panels which are flexible may have the capability of bending relatively easily without breaking. Valves 110, 110a have great utility when used with packages 111 of paperboard or polymeric materials provided with walls having properties of both flexibility and rigidity because valves 110, 110a effectively prevent excessive expansion and contraction of such packages 111. Valves 110, 110a are not limited to use with packages 111, 111a having flexible walls and may be used on packages with rigid walls.

One application for which valves 110, 110a are ideally suited is for use with packaged products that generate gas, such as dry roasted coffee 113. The coffee 113 may, for example, be in ground and/or bean form. Ground coffee 113 generates more gas volume than bean-form coffee because of the increased coffee surface area created by grinding.

Valves 110, 110a of the types described herein are engineered to both compensate for pressure changes within package 111, 111a and to compensate for changes in the pressure of ambient air surrounding package 111, 111a. Ambient air means or refers to the unconfined atmosphere or outdoor air. Ambient air pressure refers to the pressure exerted on package 111, 111a by the ambient air which can affect the expansion or contraction of package 111, 111a at a specific mean sea level geographic location as previously described.

Referring to package 111, valves 110, 110a provide for one-way gas release from package 111 to relieve pressure internal to package 111 responsible for expansion-type distortion of a flexible-walled package 111, such as illustrated in FIGS. 2A-2B with package 5. Pressure increases would occur within package 111 resulting from production of gas by coffee 113 and/or from decreases in ambient pressure, for example, when the package 111 containing coffee 113 is transported to a location with a lower ambient pressure than the point at which the coffee-type goods were originally loaded in the package 111. Valves 110, 110a serve to minimize or avoid the package swelling and expansion illustrated in FIGS. 2A-2B for package 5.

In addition, valves 110, 110a of the types described herein are further engineered to avoid or minimize contraction-type deformation and paneling of flexible-walled packages such as package 111 and package 5 illustrated in FIGS. 3A-3B and the pillow bag type package 111a. The contracted or collapsed appearance of such a package 111 may be deemed unattractive and defective by a consumer when determining whether to purchase the goods within package 111. Such contraction may be caused by increases in ambient pressure relative to pressure inside package 111 such as can occur when package 111 is transported to locations at a lower altitude than the point at which the coffee-type goods were originally loaded in package 111. Valves 110, 110a serve to minimize or avoid the package contraction and paneling illustrated in FIGS. 3A-3B for package 5.

Avoidance or minimizing of expansion or contraction of flexible-walled packages 111 are achieved by the engineered high pressure opening and closing functionality of valves 110, 110a. By high pressure opening and closing functionality, it is meant that valves 110, 110a of the types described herein both open and, especially, close when pressure inside package 111 is much higher than ambient pressure outside of package 111. This important valve structure provides for controlled release of gas pressure from within package 111 while also retaining gas pressure within package 111. Such gas pressure internal to package 111 opposes increases in ambient air pressure to avoid or minimize the contraction and paneling effect.

The high pressure opening and closing functionality of valves 110, 110a differs from existent valves 9 (FIGS. 1-3B) which remain open, and do not close, until pressure within package 5 is approximately equalized with ambient pressure effectively evacuating all gas from package 5. Packages with existent pressure relief valves 9 are subject to contraction and paneling from increases in ambient pressure.

The inventive valves 110, 110a solve the previously-described paneling problem resulting from contraction of package 111 because sufficient gas is retained within package 111 to oppose relative ambient pressure increases that would otherwise cause package 111 to contract and to form a defective paneled appearance as in FIGS. 3A-3B. And yet valves 110, 110a also permit sufficient one-way gas flow out of package 111 to avoid or minimize excessive swelling of package 111 which could be perceived by a consumer as indicating that the goods within package 111 are defective in some manner. The result of inventive valves 110, 110a is to provide for a more attractive and salable package 111 irrespective of the volume of gas produced by the goods inside the package 111 and irrespective of increases and decreases in ambient pressure which can occur between the point of packaging and delivery to the retail store shelf.

All of the foregoing considerations apply to other flexible-walled packages other than package 111, such as pillow bag package 111a. Such pillow bag packages 111a can be particularly impacted by excessive ambient pressure because the walls are quite flexible.

Package Examples

Referring then to FIGS. 4 and 7-8, the package 111 embodiment illustrated therein may be of a type used to hold consumable goods such as dry roasted coffee 113 in bean, ground, and/or other form. Package 111 may be a canister-type package comprising a tub 115 and a removable lid 117 which overlies tub 115. A consumer can remove lid 117 to scoop or otherwise obtain one or more portions of coffee 113 from tub 115. In the examples, tub 115 may include a top panel 119, side walls 121, 123, end walls 125, 127 and a bottom wall 129. Side and end walls 121, 123, 125, 127 define an opening 131 through which coffee 113 or other goods can be loaded into package 111 and through which one or more portions of coffee 113 can be removed from package 111. In the example of package 111, top panel 119 may be joined to side and end walls 121, 123, 125, 127 (for example by an adhesive, sonic welding, etc.) to serve as a closure for opening 131 and to serve as a freshness and safety seal barrier preventing any substance or thing from contacting the goods within package 111. Removable lid 117 may be sized to fit over top panel 119 and side and end walls 121, 123, 125, 127 to also enclose the goods within package 111. In the examples, top panel 119 and lid 117 may be re-closed once coffee 113 or other goods are removed from package 111.

Package 111 including top panel 119, side and end walls 121, 123, 125, 127 bottom wall 129 and lid 117 are frequently made of lightweight flexible and deformable materials. Paperboard is an example of such a suitable class of materials. Paperboard means or refers to a thick paper-based material. Paperboard is generally thicker than paper (e.g., typically in excess of about 0.012 inches thick) and has certain attributes which are superior to paper such as foldability and rigidity. According to ISO standards, paperboard is a paper with a grammage above about 250 grams/meter, but there are exceptions. Paperboard can be single-ply or multi-ply. Paperboard can be easily cut and formed, is lightweight, and because it is strong, is used in packaging such as package 111. Paperboard may be made of recycled biodegradable materials which are increasingly sought after by consumers wanting more environmentally friendly products.

In other embodiments, tub 115 may be of a unitary structure made of lightweight deformable plastic such as polyethylene terephthalate (PET), high-density polyethylene (HDPE), low-density polyethylene (LDPE), polyethylene (PE), polypropylene (PP), polystyrene (PS), and polyacetic acid (PLA) (also referred to herein as polymeric materials). Lid 117 may also be made of these materials. In other embodiments, top panel 119 may be in the form of a thin film joined to side and end walls 121, 123, 125, 127 (for example by an adhesive or heat sealing) to serve as a freshness and safety seal barrier over opening 131 preventing any substance or thing from contacting the goods within package 111 before use. Removable lid 117 may be sized to fit over the film comprising top panel 119 and side and end walls 121, 123, 125, 127 to also enclose the goods within package 111. In the examples, the material used for top panel 119 is a single-use barrier while lid 117 may be re-closed once coffee 113 or other material is removed from package 111.

Referring next to FIG. 6, there is shown a bag-type package 111a which may be of a type used to hold dry ground roasted coffee 113 or other goods. Packages 111a of this type may have a flexible or collapsible front 133, rear 135, side 137, 139, bottom 141 and top 143 walls and are sometimes referred to as a “pillow bag.” These types of packages 111a may have an upper opening, shown generally by reference number 145, and are closed or sealed once filled with coffee 113 or another type of goods. Such packages may be re-closed once coffee 113 or other goods are removed therefrom. Pillow bag-type packages 111a are particularly subject to expansion and contraction deformation because of the flexibility of the package walls 133-143. Such flexible-walls may be made of many different materials including, for example, polymeric materials, cellulosic materials, and metallic materials. Pillow bag-type packages 111a are subject to deformation from expansion whenever gas pressure within package 111a exceeds ambient pressure. Pillow bag-type packages are also subject to paneling occurring when gas pressure within package 111a is less than ambient pressure. Either of these expanded or contracted states may cause pillow bag-type packages 111a to have an appearance which may be unattractive to consumers rendering the package 111a unsalable.

Referring next to FIGS. 4-8, gas 153 to be released from package 111 collects within an interior headspace portion 155 of package 111. As illustrated in FIGS. 7-8, gas 153 is represented schematically by plural wavy lines above the ground roasted coffee 113. In the examples, headspace 155 for canister-type package 111 is bounded by top panel 119, and side and end walls 121, 123, 125, 127, while headspace (not shown) for pillow bag-type package 111a is bounded by front wall 133, rear wall 135, side walls 137, 139, and top wall 143.

Referring again to FIGS. 4-8, pressure relief valve 110, 110a may be affixed to top panel 119 over a vent 157. Vent 157 may be one or more opening provided entirely through package 111, 111a, for example, through top panel 119 or top wall 143. Pressure relief valve 110, 110a, may be affixed to any suitable exterior surface of package 111, 111a having a vent 157. In other package embodiments, vent 157 may be located in, for example, a top wall, a bottom wall, a front wall, a rear wall, a side wall, a lid, a freshness seal over an opening, a cover, or a cap of the package 111, 111a. Pressure relief valve 110, 110a may also be used on an interior surface of package 111, 111a in appropriate package embodiments.

Valve Component Examples

Referring now to FIGS. 4-15, components of embodiments of pressure relief valves 110, 110a will next be described. Particular emphasis will be placed on the unique valve structure responsible for the valves 110, 110a having the high pressure opening and closing functionality which enables the valves 110, 110a to both open and close at pressures inside package 111, 111a which are relatively greater than ambient pressure. In the examples, valve 110, 110a components may include a base layer (used interchangeably with base) 159, 159a with a vent 161, 161a, a dry strap 163 overlying vent 161, 161a, a wetting fluid 165 between base 159, 159a and dry strap 163, and a cover layer (used interchangeably with cover), or simply cover, 167 over the base 159, 159a and dry strap 163. Valve 110, 110a may include other structure as described herein.

Base Examples

Referring then to FIGS. 7-10 and 12-14, valve 110, 110a may include a gas-impervious base 159 or 159a which may also be thought of as an outer or bottom layer in the examples. Base 159, 159a should be of a gas-impervious material to block passage of any ambient air through base 159, 159a and into package 111, 111a, 111b. FIG. 14 illustrates base 159a iteration used in connection with valve embodiment 110a. In the examples, bases 159, 159a differ with respect to the vent 161, 161a structure but may otherwise be identical. For simplicity and convenience, like reference numbers are used to indicate like parts of each base 159, 159a. Each base 159, 159a provides a type of platform on which pressure relief valve 110, 110a may be constructed and which may be attached directly to package 111, 111a for example by means of adhesive 169 as described below. The term “base layer” or “base” as used herein is intended to have a broad meaning and may include, for example, a base of a single layer of material such as base 159, 159a, a laminate of multiple joined-together layers, one or more layers with a filter element, or other supportive structure for valve 110, 110a.

In the examples, base 159, 159a may include a peripheral edge 171, a first side 173, and a second side 175. Relative to the parts comprising pressure relief valve 110, 110a first side 173 may be considered an inner side while second side 175 may be considered an outer side.

In the examples, base 159, 159a may be generally flat, or planar, and may be made of a strip-type material. Referring to FIGS. 9-10, base 159, 159a may define a plane 176. Referring to FIGS. 11 and 13-14, base 159, 159a may further have a width dimension in a direction identified by the character “W” in FIG. 11 and a length dimension identified by the character “L” in FIG. 11. By way of non-limiting example only, a rectangular base 159, 159a embodiment may have length L and width W dimensions of about 0.787 inch by about 0.787 inch.

Representative materials suitable for use as base 159, 159a material can include polyethylene (PE), polypropylene (PP), and polyester (PE). An example of a suitable polyester is polyethylene terephthalate (PET). The aforementioned materials are not exclusive as other suitable materials may be implemented as base 159, 159a. Base 159, 159a may have a thickness dimension between first and second sides 173, 175 in the range of about 0.0005 inch to about 0.02 inch (0.5 mils to about 20 mils) for various iterations of valve 110. As used herein, “about” means or refers to the value given+10%.

As illustrated in the examples of FIGS. 7-13 and 15, base 159 may include a vent 161. Vent 161 consists of two apertures, or openings, 177, 179 entirely through base 159. Base 159a illustrated in FIG. 14 may also include a vent 161a. Vent 161a includes a single aperture, or opening, 181 entirely through base 159a. Each vent 161, 161a may be generally centrally disposed within peripheral edge 171 of base 159, 159a and may extend entirely through base 159, 159a, thereby allowing gas to pass through vent 161, 161a and entirely through base 159, 159a. In the examples, valve 110, 110a would preferably be affixed to an exterior surface of top panel 119 or another surface of package 111, 111a with vent 161, 161a of respective base 159, 159a over and in alignment with vent opening 157 in package 111 (FIGS. 7-8). A vent opening like vent 157 may be provided in packages 111, 111a as previously described. For instance, a top panel 119 could include a vent 157 in the form of a hole entirely therethrough and base 159, 159a vent 161, 161 would be aligned with such vent 157. According to these examples, vent 161, 161a provides part of a gas passageway 185 for gas within package 111, 111a to be directed through base 159, 159a and into and through valve 110, 110a.

Referring next to FIGS. 7-15, vent embodiments 161, 161a should have a very small cross-sectional area in plane 176 (FIGS. 9-10) defined by base 159, 159a. The vent openings in base 159 providing for gas flow through base and along gas flow path 185 may have a total cross-sectional opening area in plane 176 defined by base 159, 159a of less than about 0.00283 in². In embodiments, each opening providing an aperture (e.g., apertures 177, 179, 181) may have a diameter of about 0.010 inch providing a cross sectional area in plane 176 of 0.0000785 in². As a frame of reference, existent valves typically have a larger apertures with diameters of about 0.020 inch. In embodiments, a suitable vent total cross-sectional area range in plane 176 may be in the range of about 0.0000785 in²to about 0.00283 in². In embodiments including four apertures comprising the vent, each aperture opening could have diameters of approximately 0.010 inch and a total cross-sectional area of about 0.000314 in². In such an embodiment, each aperture opening could have a separate cross-sectional area in the range of about 0.0000196 in²to about 0.000178 in². The extremely small cross-sectional area of apertures 177, 179, 181 restricts and limits one-way gas flow out of package 111, 111a through valve 110, 110a contributing to the unique valve operation. Apertures 177, 179, 181 of such small cross-sectional area may be thought of as micro-apertures. Apertures 177, 179, 181 may be formed by any appropriate means, such as by laser drilling or punching.

It is to be understood that vents 161, 161a are examples and other vents may be implemented. For example, any number of openings through base 159, 159a may be implemented and the illustration of two apertures 177, 179 or one aperture 181 are merely illustrative. For instance, nine apertures could be implemented for a vent entirely through base 159, 159a. Apertures 177, 179, 181 configured as circles, chevrons, x-shaped apertures, and combinations of shapes and sizes of apertures may be implemented.

In a further embodiment, a base (e.g., base 159, 159a) could include a vent comprising a liquid-impervious membrane (not shown). Such a vent embodiment could be impervious to liquid while allowing passage of gas therethrough. Material used to construct such a vent could include flashspun high-density polyethylene fibers sold under the brand name TYVEK. Such liquid-impervious membrane may, for example, be located within an opening through base 159, 159a or along a first 173 or second side 175 of base 159, 159a over vent 161, 161a, thereby forming a part of base 159, 159a. Addition of a separate adhesive may be implemented as appropriate to adhere such a liquid-impervious membrane to valve 110, 110a.

A further benefit of a vent 161, 161a comprising very small apertures 177, 179, 181 (e.g., micro-aperture embodiments each having a total cross-sectional opening area in a plane defined by base 159, 159a of about 0.0000785 in²) is that such a vent 161, 161a may limit and restrict any migration of wetting fluid 165 through apertures 177, 179, 181. In other words, small openings (e.g., apertures 177, 179, 181) can contribute to avoidance of “leakage” of wetting fluid 165 from valve 110, 110a.

Adhesive Examples

Referring now to FIGS. 7-10 and 13-14, adhesive 169 may be provided on base 159, 159a second side 175 (i.e., an outer side) to both removably mount base 159, 159a and valve 110, 110a on release liner 187 (FIG. 15) and to permanently attach base 159, 159a and pressure relief valve 110, 110a to a package 111, 111a (FIGS. 4-10).

Referring once again to FIGS. 7-10, and 13-14, adhesive 169 may be deposited across base 159, 159a second side 175. As illustrated in FIGS. 7-10 and 13-14, adhesive 169 may be spaced from apertures 177, 179, 181 with a circular inner edge 189 surrounding apertures 177, 179, 181 and vent 161, 161a. Edge 189 and adhesive 169 block any lateral gas or air movement between valve 110, 110a and package 111, 111a. Adhesive 169 may be about 0.0005 inch to about 0.005 inch (about 0.5 to about 5 mils) in thickness. By way of example, types of adhesives which may be utilized include pressure-sensitive adhesives (PSAs), heat-activated adhesives, ultraviolet cured adhesives, water-based adhesives, solvent-based adhesives, and rubber-based adhesives. Acrylic adhesives are particularly preferred because they can be selected and/or formulated to have the desired oleophobic properties which is useful to avoid degradation and loss of tack (i.e., tack killing) resulting from contact with wetting fluid 165.

Dry Strap Examples

Referring again to FIGS. 7-10 and 13-14, dry strap 163 enables pressure relief valve 110, 110a to be placed in a closed state and, alternatively, in an open state. Referring to FIGS. 7 and 9, those figures illustrate valve 110, 110a in the closed state with dry strap 163 overlying and completely closing vent 161, 161a. FIGS. 8 and 10-12 are examples of valve 110 or 110a in an exaggerated open state with dry strap 163 spaced apart from at least portions of base 159, 159a and vent 161, 161a. In the closed state (FIGS. 7 and 9), dry strap 163 is in a first position blocking entry of ambient air into valve 110, 110a and package 111, 111a, 111b while also blocking gas 153 outflow from package 111, 111a if gas 153 is insufficient to open valve 110, 110a. In the open state (FIGS. 8 and 10-12), dry strap 163 is in a further position, or positions, in which valve 110, 110a permits one-way gas 153 outflow from package 111, 111a through pressure relief valve 110, 110a, along gas flow passageway 185 and out to the ambient air and surrounding environment. Dry strap 163 may, for example, function by fine undulating movement permitting separate gas bubbles to escape package 11 through valve 110, 110a. Such movement may be so fine as to not be noticeable to the human eye. Surface tension provided by wetting fluid 165 holds dry strap 163 onto base 159, 159a, facilitating the airtight seal blocking entry of ambient air through valve 110, 110a and into package 111, 111a and blocking gas 153 outflow when pressure within package 111, 111a is insufficient to open valve 110, 110a.

Pressure relief valves 110, 110a may be engineered to predictably and accurately open and close based on a known, predetermined pressure differential between pressure inside package 111, 111a and ambient air pressure outside such package. The engineered pressure differential may be considered to be a target opening or closing pressure, meaning that the pressure differential need not be identical on every opening or closing cycle. Pressure relief valve 110, 110a may be designed to open with any desired pressure differential. By way of example only, pressure relief valve 110, 110a may be designed to have a targeted opening pressure when the pressure inside package 111, 111a exceeds pressure external to package 111, 111a by about 0.725 psig (pounds per square inch gauge) to about 1.450 psig.

Importantly, pressure relief valve 110, 110a is designed to close when the targeted pressure inside package 111 exceeds pressure outside package 111 by about 0.145 psig to about 0.725 psig. It has been discovered that the structure of valve 110, 110a can be modified to open and, especially, close within the foregoing ranges. The closing pressure range provided above is greater than the closing pressures of existent valves. The inventive valves 110, 110a are capable of closing quickly after opening to retain sufficient gas pressure within package 111, 111a to resist increases in ambient pressure, thereby avoiding or minimizing contraction or paneling of package 111, 111a. This is not possible with existent valves which tend to remain open to allow pressure within package 111, 111a to approximately equalize with ambient pressure before closing.

Examples of a dry strap 163 embodiment which may be used with valve 110, 110a will now be described in connection with FIGS. 7-14. In the examples, dry strap 163 overlies vent 161, 161a between base 159, 159a and cover 167. Dry strap 163 may have a first, or outer side, side 191 facing toward cover 167 and a second, or inner, side 193 facing toward base 159, 159a first side 173. Dry strap 163 may have a thickness dimension between first side 191 (i.e., the outer side) and second side 193 (i.e., the inner side) in the range of about 0.0005 inch to about 0.002 inch (about 0.5 mil to about 2 mil) for various iterations of valves 110, 110a.

Referring to FIGS. 11, 13 and 14, dry strap 163 may have a width dimension W (See FIG. 11) between opposite sides 195, 197 of dry strap 163 which is less than the width dimension W of base 159, 159a, enabling cover 167 to be secured to base 159, 159a on opposite sides 195, 197 of dry strap 163 by adhesive 199 as described below. In embodiments, dry strap may have a width W of about 0.125 inch to about 0.25 inch (about 125 mil to about 250 mil). In embodiments exemplified by those in the data section below, a cover layer width of about 0.185 inch may be implemented to provide desired opening and closing characteristics of the valve. A narrower dry strap 163 relative to base 159, 159a and cover 167 influences and increases the pressure at which valve 110, 110a opens and closes.

Dry strap 163 may have outer edges 201, 203 defining a length dimension L (See FIG. 11) therebetween which is the same as the length L dimension of base 159, 159a. Preferably, each outer edge 201, 203 of dry strap 163 extends all the way to meet peripheral edge 171 of base 159, 159a. As illustrated in FIGS. 7 and 9, second side dry strap 163 may define and lie in a plane 205 (FIG. 9) when valve 110, 110a is in the closed state or position.

In the examples, adhesive 199 may join dry strap 163 to cover 167 and may join cover 167 ends 207, 209 outboard of dry strap 163 sides 195, 197 to corresponding spaced apart attachment regions 211, 213 of cover layer 167 and attachment regions 211a, 213b of base. Because cover 167 is unjoined to base 159, 159a between cover ends 207, 209 and attachment regions 211, 213, cover 167 is permitted to flex and to move at least partially away from base 159, 159a first side 173 (FIGS. 8, 10) along this cover region 215 which is adhered to dry strap by adhesive 199 and is unjoined to base 159, 159a when valve 110, 110a is in the open state (FIGS. 8 and 10-12) to permit gas flow out of valve 110, 110a and along gas flow path 185. Such flexing may be a slight undulating, or “burping”, movement of dry strap 163 with portions of second side of dry strap 175 spaced from plane 176 sufficiently to accommodate passage of gas bubbles between base 159, 159a and dry strap 163.

Referring to FIGS. 11-14, the gas flow path represented by the arrows 185 may extend through vent 161, 161a under dry strap 163 and may be bounded laterally by ends 207, 209 of cover 167. Gas flow path 185 channels and directs gas outflow through valve 110, 110a.

Referring again to FIGS. 7-10 and 13-14, dry strap 163 may be of a strip-type material. Dry strap 163 most preferably is of a gas-impervious material to avoid passage of ambient air through dry strap 163 and into package 111, 111a. Dry strap 163 may also be of a material which provides a vapor barrier preventing humidity in ambient air from entering package 111, 111a. Representative materials suitable for use as dry strap 163 material can include polyethylene (PE), polypropylene (PP), polyester such as PET, or other suitable material.

Cover and Adhesive Examples

In the examples and referring to FIGS. 4-15, valve 110, 110a cover layer, or cover, 167 is engineered to provide a force which holds dry strap 163 over vent 161, 161 in such a manner as to allow valve 110, 110a to both open and, especially, close at high pressures within package 111, 111a, 111b. In the examples, cover 167 overlies base 159, 159a and dry strap 163. Cover 167 may be attached to dry strap 163 and base 159, 159a for example, by means of adhesive 199 as previously described. In the examples, cover 167 may include peripheral edge 217, a first side 219 and a second side 221. Relative to base 159, 159a and dry strap 163, first side 219 of cover 167 may be considered an outer side, while second side 221 of cover 167 facing toward dry strap 163 and base 159, 159a can be considered an inner side.

In the examples, cover 167 may be made of a strip-type material. While a cover 167 of a single layer of material is shown, other arrangements are possible such as implementation of cover 167 as a plural-layer laminate.

Cover 167 may have a width dimension W and length dimension L (FIGS. 11 and 15 illustrate W and L dimensions) defining a shape and an area which are approximately the same as the width and length dimensions and area of base 159, 159a. Cover 167 peripheral edge 217 may be coextensive with base 159, 159a peripheral edge 171 as illustrated in FIGS. 7-15. Dry strap edges 201, 203 may extend to respective opposite peripheral edges of both cover 167 and base 159, 159a. By way of non-limiting example only, a rectangular cover 167 embodiment may have length L and width W dimensions of about 0.787 inch by about 0.787 inch.

Cover 167 may have a thickness dimension between first and second sides 219, 221 in the range of about 0.001 inch to about 0.007 inch (about 1 mils to about 7 mils) for various iterations of valve 110, 110a. In embodiments, the thickness dimension of cover 167 may approach about 0.020 inches (about 20 mils).

Other characteristics of cover 167 may contribute to the improved high pressure opening and closing functionality of valves 110. 110a. For example, in certain non-limiting embodiments, cover 167 may have an ultimate tensile strength of between about 200 MPa to about 220 MPa, an elongation percent of about 120% to about 165% and an elastic modulus of about 2 Newtons. Elastic modulus refers to a measurement of the cover 167 resistance to deformation when a stress (e.g., from gas pressure) is applied to it and a higher number indicates a greater stiffness. A greater tensile strength, lower elongation, and greater modulus may cause valve 110, 110a to close at higher pressures within package 111, 111a.

Cover 167 most preferably is of a gas-impervious material to prevent passage of any ambient air and moisture through cover 167 and into valve 110, 110a and possibly into package 111, 111a, 111b. Representative materials suitable for use as cover 167 material can include polyethylene (PE), polypropylene (PP), polyester such as PET, or other suitable material.

Referring to FIGS. 7-10 and 13-14, and as previously described, ends 207, 209 of cover 167 on the second side 193 of cover 167 may be joined to attachment regions 211a, 213a of base 159, 159a by adhesive layer 199 and may be unattached to base 159, 159a therebetween (i.e., unjoined region 215) allowing cover 167, and dry strap 163 adhered to cover 167, to flex slightly away from base 159, 159a so that gas 153 can flow out of valve 110. 110a along gas flow path 185 as previously described. Adhesive 199 may be the same type of adhesive as used for adhesive layer 169 on base 159, 159a second side 175. Cover 167 attachment regions 211, 213 may be joined to base 159, 159a attachment regions 211a, 213a by means other than adhesive 199 such as sonic welding.

Valves 110, 110a have been described above in connection with base 159, 159a, dry strap 163, and cover 167 components which are generally rectangular in configuration. However, valves 110, 110a may be provided in shapes other than the rectangular shapes illustrated and described. By way of example only, base 159, 159a, dry strap 163, and cover 167 of valves 110. 110a may have circular shapes, or hexagonal shapes, or polygonal shapes depending on the needs of the end user. For instance, a particular customized configuration of valve 110, 110a might be more aesthetically consistent with the package 111, 111a on which the valve 1110, 110a is to be affixed and the valve 110, 110a may be configured accordingly consistent with the invention.

Wetting Fluid Examples

Referring to the examples of FIGS. 4-14, valves 110, 110a of the type described herein are engineered for use with a wetting fluid 165 for the purpose of improving sealing closure of dry strap 163 against base 159, 159a to completely block ambient air entry into valve 110, 110a through vent 161, 161a. Referring to the exploded views of FIGS. 13-14, wetting fluid 165 wets first side 173 (i.e., the inner side) of base 159, 159a and second side 175 (i.e., the inner side) of dry strap 163 providing a surface tension which improves the aforementioned sealing closure of base 159, 159a and dry strap 163 around vent 161, 161a. Wetting fluid 165 may be deposited on first side 173 of base 159, 159a under dry strap 163 and completely around vent 161, 161a and on barrier portions. Wetting fluid 165 plates out onto at least first side (i.e., the inner side) 173 of base 159, 159a and second side 175 (i.e., the inner side) of dry strap 163 to wet and provide the surface tension between base 159, 159a and dry strap 163, improving the closure of valve 110, 110a. By way of non-limiting example, about 1.5 μL to about 2.3 μL of wetting fluid may be used for a valve having an area of about 0.039 in²(25 mm²).

Wetting fluid 165 imparts excellent performance benefits to valve 110, 110a, including providing an excellent airtight seal of the valve 110, 110a while allowing very delicate (i.e., quite small or fine) opening and closing movements of the valve 110, 110a, including undulating (i.e., burping) movement enabling gas bubble flow through passageway 185 between base 159, 159a and dry strap 163. Valves 110, 110a including a wetting fluid 165 can be engineered to open and close at predictable, high relative pressures within package 111, 111a as described herein.

Examples of wetting fluid 163 may be silicone oil, a graphite impregnated oil, a food grade oil, food grade silicone grease, or other viscous fluid.

Wetting fluid 165 may have a viscosity range of about 100 centipoise to about 1000 centipoise (“cP”), with a further preferred range being about 150 cP to about 500 cP and a viscosity of about 180 cP to about 350 cP being particularly effective in certain embodiments. Food grade silicone grease used as a wetting fluid in some applications can have a viscosity of 1,000 centipoise. The viscosity of wetting fluid 165 can also be selected to adjust and select the target opening and closing pressures of valve 110, 110a. The pressure will be greater with more viscous wetting fluids 165 and vice-versa. Therefore, selection of a wetting fluid 163 can be used to adjust or “fine tune” the performance of valves 110, 110a. The wetting fluid viscosity can be modified based on other variables or needs of the end user. For instance, a viscosity of 350 cP may be suitable for certain valve iterations.

Wetting fluid 163 may be applied to valve 110, 110a at any suitable point including during valve 110, 110a manufacture or as the pre-manufactured valve is applied to the package (e.g., package 111).

Other Structure

Referring to FIGS. 7-10 and 13-15, valve 110, 110a may optionally include rails 223, 225 (also sometimes referred to as “bumpers”) on first side 219 (i.e., outer side) of cover 167. Rails 223, 225 may be secured to cover 167 by an adhesive 227. The valve 110 iteration of FIGS. 11-12 lacks rails 223, 225 illustrating the optional nature of rails 223, 225. Adhesive 227 may be identical to the adhesive provided as adhesive layers 169, 199 as previously described. If provided, rails 223, 225 serve as bumpers or spacers to space dry strap 163 and cover 167 from adjacent packages and objects avoiding application of force to dry strap 163 and cover 167 that could interfere with movement of dry strap 163 to the open position of FIGS. 8 and 10-12 and providing for improved valve 110, 110a operation.

Release Liner Examples

Referring now to FIG. 15, an exemplary series of four pressure relief valves, each indicated as 110 for convenience, are shown mounted on a fragment of a release liner 187. Valves 110a may each be mounted to release liner 187 in an identical manner to that shown in FIG. 15. Valves 110, 110a may be removed from release liner 187 and may be attached to a package, such as package 111 and 111a of FIGS. 4-8. Release liner 187 may be of a material to which adhesive 169 can temporarily attach valves 10 without damaging adhesive 169. Examples include Typical release liners would include Polyester films polypropylene films, Paper release liners or cellulose films.

Release liner 187 carries pressure relief valves 110 (or valve 110a) until the valves 110 are removed during the process of attaching valves 110 to package 111, 111a, for example, by automated application equipment. As illustrated in FIG. 15, valves 110 may be conveniently spaced apart at regular intervals along release liner 187, as for example, at a one inch interval between centers, although the repeat spacing is also dependent on the packaging application.

Other Pressure Relief Valve Examples

In certain “green” applications in which eco-friendly materials are required, it may be desirable for pressure relief valve 110, 110a to be constructed of compostable materials, that is, materials which will decompose when in a landfill. Where such decomposition is desired, base 159, 159a, dry strap 163, cover 167 and other valve 110, 110a components may be made of polylactic acid, cellulose acetate, or other compostable materials.

Operation

Referring to FIGS. 4-14, operation of valve examples 110, 110a will now be described in the context of the problems described previously in connection with FIGS. 1-3B. In the examples, pressure relief valve 110, 110a is initially affixed to a package 111, 111a over package vent 157 with valve vent 161, 161a in gas flow alignment with package vent 157 and with circular edge 189 of adhesive 169 completely surrounding package vent 157 so as to prevent ambient air from entering package 111, 111a between package 111, 111a and valve 110, 110a. Adhesive 169 secures valve 110, 110a to package 111, 111a.

Pressure relief valve 110, 110a is initially in a first, or closed, state similar to that shown in FIGS. 7 and 9. In this closed state of the examples, dry strap 163 second side 193 may abut base 159, 159a first side 173 with wetting fluid 165 surrounding vent 161, 161a. Wetting fluid 165 provides surface adhesion between dry strap 163 and base 159, 159a and cover 167 provides a force which serves to urge dry strap 163 sealingly against base 159, 159a. A cover 167 having structure as described herein may have stiffness characteristics useful to press dry strap 163 against base 159, 159a to close vent 161, 161a blocking movement of gas 153 through vent 161, 161a and preventing ambient air from entering package 111, 111a, thereby preserving the freshness of coffee 113 or other material inside package 111, 111a.

In the examples of pressure-relief valve 110, 110a, when pressure inside package 111 builds to exceed the predetermined and known target pressure, valve 110, 110a will at least partially open to allow gas to escape from package 111, 111a and through valve 110, 110a (via gas passageway 185). In the embodiments of valves 110, 110a, force applied through vent 161, 161a and against dry strap 163 along gas flow passageway 185 causes at least partial separation of dry strap 163 from base 159, 159a first surface 173 so that valve 110, 110a is in the open state such as in the examples of FIGS. 8 and 10-12 as previously described. For both valves 110, 110a, flexure of cover 167 may allow complete, partial, or undulating separation of dry strap 163 from base 159, 159a to open gas flow path 185, allowing gas to escape from package 111, 111a when valve 110, 110a is in the open state. Most typically, there will be a gradual undulating movement of dry strap 163 as individual gas bubbles pass between dry strap 163 and base 159, 159a.

Importantly, pressure-relief valve 110, 110a, with high pressure opening and closing functionality now behaves in a manner quite unlike existent valves 9 (FIG. 1). Each pressure-relief valve 110, 110a initially allows some gas to evacuate package 111, 111a. But rather than remain in the open state (FIGS. 8, 10, 11-12, 15-16) until pressure within package 111, 111a equalizes with ambient air pressure, valves 110, 110a close to retain gas within package 111, 111a. For example and as previously described, pressure relief valve 110, 110a may be designed to have a targeted opening pressure when the pressure inside package 111, 111a exceeds ambient pressure external to package 111, 111a by about 0.725 psig to about 1.450 psig.

Importantly, pressure relief valve 110, 110a may be designed to close when the targeted pressure inside package 111 exceeds pressure outside package 111 by 0.145 psig to about 0.725 psig. Cover 167 with structure as described herein applies a force as it returns to its original position. The thickness of dry strap 163 in the range described herein may increase the force applied by cover 167 by tensioning cover 167. In the embodiments of valves 110, 110a, the strong force applied by cover 167 causes dry strap 163 to be relocated fully against base 159, 159a with wetting fluid 165 plated out therebetween, closing vent 161, 161a and returning pressure relief valve 110, 110a to the closed state of FIGS. 7 and 9, thereby retaining some gas within package 111, 111a. Improved valves 110, 110a close to retain pressure within package 111, 111a which differs from existent valves that remain open until pressure within package 111, 111a is approximately the same as the ambient pressure approximately equalizing pressure inside package 111, 111a with ambient pressure. In such an equalized pressure state, package 111, 111a would be subject to contraction and paneling if ambient pressure were to increase.

Table 1 presents three examples of actual experimental ranges of opening and closing pressures capable of being achieved with valves 110, 110a according to the invention.

TABLE 1

Valve Opening and Closing Pressure Ranges (psig/millibar)

Opening
Closing
Ratio

No.
pressure
pressure
Open:Close

1
0.725-1.450 psig
0.145-0.725 psig
2-5

(50-100 mbar)
(10-50 mbar)

2
0.870-1.160 psig
0.363-0.653 psig
1.78-2.40

(60-80 mbar)
(25-45 mbar)

3
0.943-1.015 psig
0.435-0.580 psig
1.75-2.17

(65-70 mbar)
(30-40 mbar)

The process of opening and closing pressure relief valve 110, 110a is repeated when pressure inside package 111, 111a again exceeds the target opening pressure relative to the pressure of the ambient air outside package 111, 111a and can continue until all of the coffee 113 or other gas-producing material is removed from package 111, 111a.

Without wishing to be bound by any particular theory, opening and, especially, closing pressures of valve 110, 110a can be adjusted by modification of the valve 110, 110a structure. Modification of the thickness of cover 167 between the first and second sides 219, 221 of cover 167 to include greater thicknesses is thought to increase the force applied by cover 167 to assist the valve 110, 110a to open and, especially, close at higher pressures internal to package 111, 111a. Other factors such as cover 167 modulus, tensile strength, and elasticity also play a role in force applied to dry strap 163 and vent 161, 161a to close valve 110, 110a.

Modification of the thickness of dry strap 163 between the first and second sides 191, 193 of dry strap 163 with greater thicknesses tensions or stretches cover 167. The increase in tension of cover 167 increases the force applied over vent 161, 161a to thereby increase the pressure at which valve 110, 110a opens and, especially, closes.

Modification of the width W of dry strap 163 relative to the width W of cover 167 and base 159, 159a with narrower relative dry strap 163 widths W is another factor which increases the pressure at which valve 110, 110a opens and, especially, closes. More specifically, a narrower dry strap 163 relative to the area of base 159, 159a and cover 167 between attachment regions 211, 211a, 213, 213a has the effect of stiffening dry strap 163 such that valve 110, 110a both opens and closes at higher pressures within package 111, 111a relative to ambient air pressure. The decrease in surface area of dry strap 163 influences and increases the pressure at which valve 110, 110a opens and closes.

Modification of the viscosity of wetting fluid 165 influences the opening and closing pressures of valve 110, 110a. More viscous wetting fluids 165 tend to increase the pressure at which valve 110, 110a opens and closes.

Combinations of the foregoing structural factors can be implemented to fine tune the pressures at which the valve 110, 110a opens and, especially, closes. These results represent unexpected outcomes because it had been thought that valves modified in the foregoing manner(s) would be inoperative to allow adequate gas 153 to be adequately and consistently purged from package 111, 111a.

Inventive valves 110, 110a are engineered to avoid or minimize both the swelling and paneling deformations of flexible-walled packages 111, 111a described in the scenario of FIG. 1. A package 111, 111a transported to second location 13 at an elevated MSL (relative to first location 1) would expand only modestly in response to the decreased ambient pressure and pressure within package 111, 111a because valve 110, 110a would allow evacuation of some gas 153 from within package 111, 111a. A paperboard-type canister package 111 would be sufficiently robust to avoid or minimize noticeable package 111, 111a deformation. Gas 153 would be retained within package 111 (and package 111a), however, because of the engineered closure of valve 110, 110a.

Transportation of package 111, 111a to third location 17 at sea level (an MSL less than that of second location 13) and the resultant increase in ambient pressure would not cause package 111, 111a to excessively deform by collapsing or paneling because sufficient gas 153 and pressure would be retained within package 111, 111a to oppose the expected increase in ambient pressure at third location 17. The result of inventive valves 110, 110a is to provide for a more attractive and salable package 111, 111a irrespective of the volume of gas 153 produced by the goods inside the package 111, 111a and irrespective of increases and decreases in ambient pressure which can occur between the point of packaging and delivery of package 111, 111a to the retail store shelf.

EXAMPLES

Experimental valves according to the invention were compared with an existent valve provided as a control to demonstrate that the structure of the experimental valves quantitatively provides both opening and closing characteristics which differ materially from those of the control. The data show that valves according to the invention both open and close at high relative pressures in a manner which is different from, and unlike, the control valve. The Examples demonstrate that valves according to the invention have the capability of eliminating or reducing both excessive expansion and contraction of flexible-walled packaging providing for an aesthetically improved package while also maintaining the quality of the packaged product.

Example 1

Evaluation of each experimental and control valve in Example 1 and in the following Example 2 was conducted in the same manner as described herein. Valve operation was determined using a PVT-300 brand test unit available from Plitek LLC of Des Plaines, Illinois. The PVT-300 is an industry-standard analytical unit purposed to quantify the pressure at which a one-way pressure relief valve opens and, alternatively, closes. The PVT-300 is capable of use with a stand-alone valve prior to application of the valve to a package and also with a valve once the valve is affixed to a package. Therefore, the PVT-300 is capable of reproducing pressures exerted from within a package for both opening and closing of a one-way pressure relief valve. Closing of the valve is particularly important because such closure both blocks entry of ambient air into the package and determines the pressure retained within the package. Closing at an elevated relative pressure within the package is important to avoid package contraction by retaining pressure within the package to resist paneling responsive to increases in ambient pressure.

The PVT-300 is capable of injecting small amounts of air into vent 161, 161a of valve 110, 110a to simulate gas flow out of a package and through the valve 110, 110a to the ambient air. Gas output from the PVT-300 may be in units of standard cubic centimeters per minute (SCCM). In the examples, the PVT-350 was configured to deliver gas to the experimental and control valves at a flow rate of approximately 35 SCCM which is a flow rate replicating the off-gassing of roasted coffee in bean and ground forms.

Each test consisted of two opening and closing cycles. In the first cycle, pressure was increased in units of pounds per square inch gauge (psig) until the valve opened followed by a decrease in pressure until the valve closed. A holding period of 60 seconds was interposed between the first and second cycles at the pressure indicated in Table 3 and Table 5. During the second cycle the process was repeated with pressure again increased until the valve opened followed by a reduction in pressure until the valve closed. It is expected that the opening and closing pressures on the second cycle would be slightly less than those of the first cycle because the surfaces of the dry strap and base require re-wetting following closing. The two cycles provide a basis for comparison between iterations of the experimental and control valves.

In Example 1, the experimental and control valves each consisted of a base, a dry strap, and a cover as described in Table 2. The adhesive used to bond the cover to the base was an acrylic adhesive. A wetting fluid was provided between the dry strap and base as in Table 2. The control valve was a model PV-425-FV available from Plitek LLC. The PV-425-FV is an industry-leading valve.

TABLE 2

Base
Dry
Cover
Wetting

Layer
Strap
Layer
Fluid
Adhesive

Control
5 mil thickness
Width 0.394
1 mil
Silicone
Acrylic

Valve
PET, vent with 9
inch, 0.5 mil
thickness
oil
adhesive

openings
thickness
PET
181 cps

Total opening
PET

cross sectional

area 0.002827 in²

Experimental
5 mil thickness
Width 0.185
5 mil
Silicone
Acrylic

Valve 1
PET, vent with
inch, 1 mil
thickness
oil
adhesive

four openings
thickness
PET
350 cps

Total opening
PET

cross sectional

area 0.0003140 in²

The results of Example 1 are presented in Table 3 and graphically in FIG. 16. Such results demonstrate that a valve according to the invention both opens and closes at pressures materially greater than the control valve.

TABLE 3

First
First
60 Second
Second
Second

Open
Close
Hold
Open
Close
Ratio 1^st

(psig)
(psig)
(psig)
(psig)
(psig)
Open:Close

Control
0.27
0.035
0.037
0.248
0.033
7.71

Valve

Experimental
1.164
0.577
0.577
1.052
0.541
2.02

Valve 1

The data show that experimental valve 1 according to the invention opened at a pressure over 4 times greater than the control valve and closed at a pressure over 16 times greater than the control valve to yield a ratio of first opening pressure to first closing pressure of 2.02. These material differences are particularly apparent from the graphical data of FIG. 16. The greater opening to closing ratio of 7.71 for the control valve demonstrates that the control valve would remain open until pressure within and outside the package were essentially equalized. The much lower opening to closing ratio of experimental valve 1 demonstrates that the experimental valve would close much earlier than the control to retain pressure within the package that would counteract increases in ambient pressure to avoid contraction and paneling of the package. This functionality of the control valve is excellent and well-suited for innumerable one-way valve applications. The data show, however, that the inventive valve provides excellent results in applications where material changes in ambient pressure would be expected and where avoidance of both undue expansion and contraction of the product package are of great importance.

Example 2

Experimental valve 1 and three additional experimental valves identified as Valves 2-4 were compared to an existent Plitek PV-425-FV valve using a procedure identical to that described in connection with Example 1. Table 4 describes the control valve and experimental valves 1-4.

TABLE 4

Base
Dry
Cover
Wetting

layer
Strap
Layer
Fluid
Adhesive

Control
5 mil thickness
Width
1 mil
Silicone
Acrylic

Valve
PET, vent with
0.394 inch,
thickness
oil
adhesive

9 openings
0.5 mil
PET
181 cP

Total cross
thickness

sectional
PET

opening area

0.002827 in²

Experimental
5 mil thickness
Width
5 mil
Silicone
Acrylic

Valve 1
PET, vent with
0.185 inch,
thickness
oil
adhesive

four openings
1 mil
PET
350 cP

Total cross
thickness

sectional
PET

opening area

(0.0003140 in²)

Experimental
5 mil thickness
Width
5 mil
Silicone
Acrylic

Valve 2
PET, vent with
0.125 inch,
thickness
oil
adhesive

three openings
0.5 mil
PET
350 cP

Total cross
thickness

sectional
PET

opening area

0.0002360 in²

Experimental
5 mil thickness
Width
5 mil
Silicone
Acrylic

Valve 3
PET, vent with
0.185 inch,
thickness
oil
adhesive

one opening
1 mil
PET
350 cP

Total cross
thickness

sectional
PET

opening area

0.00007854 in²

Experimental
5 mil thickness
Width
5 mil
Silicone
Acrylic

Valve 4
PET, vent with
0.185 inch,
thickness
oil
adhesive

two openings
1 mil
PET
350 cP

Total cross
thickness

sectional
PET

opening area

0.0001570 in²

The results of Example 2 are presented in Table 5 and graphically in FIG. 17. The results of Example 2 demonstrate that valves according to the invention consistently both open and close at pressures which are materially greater than the pressures at which the control valve both opens and closes.

TABLE 5

First
First
60 Second
Second
Second

Open
Close
Hold
Open
Close
Ratio 1^st

(psig)
(psig)
(psig)
(psig)
(psig)
Open:Close

Control
0.270
0.035
0.037
0.248
0.033
7.71

Valve

(From

Table 4)

Experimental
1.164
0.577
0.557
1.052
0.541
2.02

Valve 1

(From

Table 4)

Experimental
1.442
0.151
0.147
0.538
0.126
13.11

Valve 2

Experimental
1.092
0.570
0.559
0.904
0.535
1.92

Valve 3

Experimental
1.361
0.600
0.581
1.204
0.547
2.27

Valve 4

The data show that experimental valves 1, 3 and 4 both opened and closed at pressures much greater than the control valve. Even experimental valve 2 closed at a pressure greater than the control valve. The graphical data of FIG. 17 illustrate the striking difference in operation of the respective control and inventive valves. The data of Example 2 demonstrate that the experimental valves would close much earlier than the control, thereby retaining pressure within the package resistant to increases in ambient pressure that would cause contraction and paneling of a flexible-walled package. The data of Example 2 demonstrate that a range of inventive valves are effective at both opening and closing at relatively high pressures in ways that differ greatly from the control valve.

The foregoing description is provided for the purpose of explanation and is not to be construed as limiting the invention. While the invention has been described with reference to preferred embodiments or preferred methods, it is to be understood that the words which have been used herein are words of description and illustration, rather than words of limitation. Section headings are non-limiting and are provided for the reader's convenience only. Furthermore, although the invention has been described herein with reference to particular structure, methods, and embodiments, the invention is not intended to be limited to the particulars disclosed herein, as the invention extends to all structures, methods and uses that are within the scope of the appended claims. The disclosed one-way pressure relief valves may address some or all of the problems previously described.

A particular embodiment need not address all of the problems described, and the claimed pressure relief valves should not be limited to embodiments comprising solutions to all of these problems. Further, several advantages have been described that flow from the structure and methods; the present invention is not limited to structure and methods that encompass any or all of these advantages. Those skilled in the relevant art, having the benefit of the teachings of this specification, may effect numerous modifications to the invention as described herein, and changes can be made without departing from the scope and spirit of the invention as defined by the appended claims. Furthermore, any features of one described embodiment can be applicable to the other embodiments described herein.

	Number	Date	Country
Parent	PCT/US2021/053398	Oct 2021	WO
Child	18624502		US

Pressure Relief Valve with High Pressure Opening and Closing Functionality

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