Patent Description:
Dry roasted coffee is most flavorful when packaged immediately following the production process. It is desirable to package the coffee immediately after roasting and processing because contact between the coffee and ambient air can oxidize the coffee, causing a degradation in coffee flavor.

An obstacle to immediate packaging of the coffee is the well-known fact that roasted coffee produces large volumetric amounts of gas, including carbon dioxide gas. If the coffee is packaged in a flexible package, such as a pillow bag, the gas will cause the package to expand and to distort, potentially resulting in failure of the package or making the package appear swollen and unattractive to a consumer. The rate of gas production by the coffee can be decreased by degassing the coffee before packaging. Degassing involves holding the freshly roasted coffee in large bins for up to <NUM> hours. During this degassing period, the freshly roasted coffee can absorb ambient oxygen causing the aforementioned degradation and loss of flavor to occur. Degassing the coffee extends the time before the coffee can be packaged making the packaging process less efficient and more costly. Adding to the cost is that a large investment must be made in the physical plant and in the degassing tables and other equipment needed to process the coffee.

A solution to the aforementioned problems is to package the coffee immediately after roasting and processing in a package including a one-way pressure relief. A pressure relief valve provides an opportunity to release gas from the package while protecting the coffee from any contact with ambient air and the resultant oxidation. More specifically, the pressure relief valve is attached to, or is a part of, the coffee package. The pressure relief valve allows high-pressure gas out of the package while preventing ambient air from entering the package and coming into contact with the coffee.

It is important that the pressure relief valve provide an air-tight seal when pressure within the package is below that required to open the valve. Such air-tight seal is necessary to prevent the ambient air from entering the package. The air-tight seal must reform after each opening and closing of the valve and that seal must form responsive to delicate (i.e., quite small) opening and closing movements of the valve components.

Certain pressure relief valves utilize a component referred to in the valve industry as a "dry strap" or simply as a "strap" in combination with a fluid which wets a surface of the dry strap to control the one-way flow of gas through the valve. Such a dry strap is typically a strip-like layer or membrane which overlies a vent provided in a base or other part of the valve. The dry strap provides a closure around and over the vent which permits gas outflow while blocking ambient air inflow.

The wetting fluid, such as a silicone oil, a graphite impregnated oil, a food grade oil, or a food grade silicone grease is typically added between the dry strap and base and around the vent to wet the facing surfaces of the dry strap and base. The surface tension provided by the wetting fluid enables the dry strap to provide a complete closure of the dry strap against the base or other element of the valve, sealing the vent. The wetting fluid may be applied just before the valve is applied to the package or at the time of valve manufacture.

One-way pressure relief valves including a wetting fluid have performance benefits making them excellent for their intended purpose. The wetting fluid provides for an excellent air-tight seal of the valve. The wetting fluid allows the valve to open and close notwithstanding the very delicate opening and closing movements of the dry strap of the valve. And, valves including a wetting fluid can be engineered to open and close at predictable, low pressures.

However, the use of a wetting fluid introduces potential complexities with respect to use of the valve. Liquid-type wetting fluids typically used in pressure relief valves have flow properties. Consequently, it is possible that the wetting fluid can migrate or "leak" out of the valve. Typically, an amount of wetting fluid in excess of the amount needed to adequately wet the valve is utilized in anticipation that some of the wetting fluid will inevitably migrate out of the valve.

<CIT> discloses a known package with a pressure relief valve. The wetting fluid, which is disposed between a dry strap and a base of the package, causes surface adhesion between the dry strap to the base, thereby blocking movement of gas through a vent while preventing gas within the package from escaping to the atmosphere and preventing and vice versa preventing ambient air from entering into the package. Certainly, there is no provision to prevent the wetting fluid from draining out of the package during handling and transport of the letter.

It is desirable that migration of wetting fluid from the valve be minimized or avoided. Contact between any wetting fluid and the exterior surfaces of the valve or the exterior surfaces of the package to which the valve is attached can make the valve and package feel greasy potentially diminishing the appearance of the product to a consumer.

Wetting fluid which migrates out from within the valve can also come into contact with adhesive on the outer side of the valve provided to temporarily secure the valve to a release liner or to permanently secure the valve to a package. Contact between the wetting fluid and adhesive can lessen the effectiveness of the adhesive. This is referred to as "killing" the tack provided by the adhesive. If the adhesive fully or partially fails, then the valve may become fully or partially detached from the release liner on which the valve is supplied potentially resulting in incorrect application of the valve to the package. Obviously, any valves which become contaminated by contact between the wetting fluid and adhesive may have to be discarded. And, any adhesive failure can result in the valve becoming detached from the package after application thereto, potentially allowing for spoilage of the coffee or other product due to contact with ambient air.

As can be appreciated, the foregoing problems can be exacerbated if excess amounts of wetting fluid are utilized to compensate for anticipated leakage. For these and other reasons it is desirable to use only the minimum amount of wetting fluid necessary to adequately wet the valve surfaces.

It would be an improvement in the art to provide a one-way pressure relief valve which enjoys the performance benefits provided by use of a wetting fluid yet avoids the potentially detrimental effects caused by "leaking" of the wetting fluid onto exterior surfaces of the valve, which enables the exterior surfaces of the valve to appear to be an indistinguishable part of the package, and which enables the valve to remain securely on the release liner before application to the package and to remain affixed to the package once applied thereto, all thereby contributing to a perceived improvement in the quality of the packaged goods.

The present invention relates to improved one-way pressure relief valves with wetting fluid reservoirs. The valves may be used to eliminate gas from a package while blocking ambient air from entering the package potentially damaging the goods within the package. The valves utilize a wetting fluid to improve closure of the valve. The wetting fluid reservoirs lessen or eliminate migration (i.e., "leaking") of the wetting fluid from the valve by providing storage locations for the wetting fluid. Avoidance of migration of wetting fluid out of the valve provides an opportunity for performance benefits. Benefits may include predictable and accurate valve opening and closing, maintenance of the appearance of the valve and package, and maintenance of adhesion between the valve and the release liner or package to which the valve is attached.

The pressure relief valve with wetting fluid reservoirs according to the invention includes the features of claim <NUM>. A base has a first side, a second side, an area, a peripheral edge, and a vent preferably formed by one or more apertures extending entirely through the base. The cover overlies the base and may overlie the dry strap. The cover has a first side, a second side, a cover area, a peripheral edge, and opposite end portions secured with respect to the base. The dry strap overlies the entire vent with a second side of the dry strap facing the first side of the base and such facing side of the dry strap at least partially abut the first side of the base. The wetting fluid is disposed within the plurality of the reservoirs and between the dry strap and the base entirely around the vent. The pressure relief valve with the wetting fluid reservoirs further comprises at least one microscopically textured surface on the second side of the dry strap facing the base, or on the first side of the base facing the dry strap, or on the both the first side of the base and the second side of the dry strap. The at least one microscopically textured surface defines a plurality of fluid-holding reservoirs therein.

In certain non-limiting embodiments, the dry strap may optionally have a width in a first direction which is less than the widths of the base and cover.

The fluid reservoirs may be provided on all or a part of a textured surface or surfaces of the valve. The textured surface may include outer surface portions and inner surface portions and at least the inner surface portions define the reservoirs. The reservoirs provide microscopic volumetric spaces (i.e., small pockets or voids) which collect and hold the wetting fluid lessening or preventing the wetting fluid from migrating out of the valve. In certain preferred embodiments, the textured surface is located on just the second side of the dry strap facing the base. In such embodiments, a textured surface on the base first side becomes unnecessary.

Different types of textured surfaces may be implemented. For example, the outer surface portions and the inner surface portions of the textured surface may be irregular. By way of further example, the outer surface portions and the inner surface portions of the textured surface may be of a regular repeating pattern. Combinations of irregular and regular outer and inner and surfaces may be implemented.

In embodiments, the textured surface may have a matte-finish type appearance indicative of a microscopic rough or unsmooth surface or consistency defining the reservoirs. Such a matte-finish appearance may be created in a surface of the dry strap and/or base by various means such as by chemical etching, plasma treating, and laser-ablading.

The wetting fluid may be disposed between the dry strap and the base entirely around the vent and within a plurality of the reservoirs. The wetting fluid helps to form an air tight seal between the dry strap and base closing the vent when the valve is in its closed state.

In another aspect of the invention, an adhesive may be on the second side of the base to secure the valve to a surface such as a release liner or package. In use, the adhesive may attach the valve to the package with the vent in the base over, surrounding, and in alignment with a vent in the package. The adhesive may be selected from the group consisting of pressure-sensitive adhesives (PSAs), heat-activated adhesives, ultra-violet cured adhesives, water-based adhesives, solvent-based adhesives, and rubber-based adhesives. In particular embodiments, the adhesive selected may be of an oleophobic type. Oleophobic adhesives are examples of types of adhesives with desirable resistance to loss of adhesion potentially caused by contact with the wetting fluid.

Wetting fluids which may be implemented to provide predictable and precise opening and closing of the valves may include silicone oil, graphite-impregnated oil, food grade oil, and food grade silicone grease. The volumetric amount of wetting fluid may be selected based on factors such as the size of the valve. In some embodiments, about <NUM>µL to about <NUM>µL of wetting fluid may be used. In still another aspect of the invention, the wetting fluid may have a viscosity engineered to minimize leaking. For instance, the viscosity and flow rate of the wetting fluid may be adjusted to minimize leakage. The wetting fluid may be engineered to have a viscosity of about <NUM> centipoise to about <NUM> centipoise so as to accomplish minimization of fluid migration.

The vent in the base may be a single opening or a plurality of openings. Plural openings may be defined by a plurality of aperture and barrier portions. In embodiments, the barrier portions defining the apertures may be spaced apart by about <NUM> inches (i.e. <NUM>,<NUM>) or less. Such small apertures may obstruct passage of small particles, such as coffee particles, from entering the valve and interfering with valve opening and closure. Such small apertures in combination with a wetting fluid of an appropriate viscosity, may also minimize migration of wetting fluid out of the valve through the apertures.

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

Examples of pressure relief valves having wetting fluid reservoirs 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.

As illustrated in <FIG> and <FIG>, the present invention relates to improved one way pressure relief valves, embodiments of which are indicated by reference numbers <NUM> and 10a. Valves <NUM>, 10a of the types described herein may be for releasing gas from a product package <NUM> such as the bag-type package <NUM> illustrated in <FIG>. Certain components of exemplary valves <NUM>, 10a may be alike and, for convenience and brevity, such components are discussed concurrently and have like reference numbers. A feature of valve <NUM> is that it is provided with a textured surface <NUM> including a plurality of wetting fluid reservoirs <NUM> (also referred to simply as reservoirs <NUM>) for holding a wetting fluid <NUM>. In the further example of valve 10a illustrated in <FIG>, plural textured surfaces <NUM>, 13a are provided and each has wetting fluid reservoirs <NUM>. In the examples and as will be described herein, many reservoirs may be provided and, for convenience and brevity, reference number <NUM> is used to indicate representative ones of the reservoirs <NUM>.

Retention of wetting fluid <NUM> within reservoirs <NUM> represents an improvement in the field of pressure relief valves. Retention of wetting fluid <NUM> within valve <NUM>, 10a limits or eliminates migration or "leakage" of wetting fluid <NUM> out from valve <NUM>, 10a where the wetting fluid <NUM> can disadvantageously impart a greasy feeling to the outside of the valve <NUM>, 10a or the outside of package <NUM>. Therefore, valve <NUM>, 10a provides an opportunity to maintain the attractive feel and appearance of the valve <NUM>, 10a and package <NUM>. Retention of wetting fluid <NUM> can also avoid lessening of adhesion of the valve <NUM>, 10a as can occur if wetting fluid comes into contact with the adhesive used to hold valve <NUM>, 10a to a release liner <NUM> (<FIG>) or to package <NUM> (<FIG>). Other valve <NUM>, 10a structure and improvements may be provided to further facilitate retention of wetting fluid <NUM> within valve <NUM>, 10a as described herein.

Referring then to <FIG>, the package <NUM> example illustrated therein may be of a type used to hold consumable goods such as dry ground roasted coffee <NUM>. Packages <NUM> of this type may have a flexible or collapsible wall or walls <NUM> and are sometimes referred to as a "pillow bag. " These types of packages <NUM> are closed or sealed once filled with coffee <NUM> or another material. Such packages may be re-closed once coffee <NUM> or other material is removed therefrom. Gas produced internal to package <NUM> by gas-producing material, such as ground roasted coffee, can cause the package <NUM> wall or walls <NUM> to expand and take on a swollen appearance which may be unattractive to consumers. The expanded volumetric size of a swollen package <NUM> may make it problematic to hold multiple packages <NUM> in a single box, or to store packages <NUM> on a grocery store or household shelf.

Referring next to <FIG> and <FIG>, gas to be released from package <NUM> is within an interior portion <NUM> of package <NUM> bounded by walls <NUM>. It should be noted that the gas to be released from package <NUM> could be from a source other than a gas-producing material within package <NUM>. For example, gas within the interior portion <NUM> of package <NUM> could be entrapped air remaining in the package <NUM> following the packaging process. Gas could be entrapped within a head space of package <NUM> during packaging of any bulk material (e.g., granular animal food). Such entrapped gas could expand the volumetric size of the package <NUM> making the package <NUM> less compact and requiring more space for storage of the package <NUM> or making it difficult to stack the packages for palletized shipment. In such a setting, a pressure relief valve <NUM>, 10a could be used to allow the package <NUM> to be compressed to evacuate gas through the valve <NUM>, 10a, thereby reducing the volumetric size of package <NUM>.

Accordingly, pressure relief valve <NUM>, 10a may be used with any type of package wherein it is desired to release gas therefrom and the bag-type package <NUM> illustrated in <FIG> is merely one example of a package <NUM> which may be used with pressure relief valve <NUM>, 10a. Representative examples of other types of packages which may be used with pressure relief valve <NUM>, 10a include flexible and rigid cans, packs, bags, and pouches.

Pressure relief valve <NUM>, 10a is preferably affixed to an exterior surface <NUM> of package <NUM> over a vent opening <NUM> provided entirely through package <NUM> wall <NUM>. Vent opening <NUM> in package <NUM> may be a hole or holes in wall <NUM>. Pressure relief valve <NUM>, 10a may be affixed to any suitable exterior surface <NUM> of package <NUM> having a vent opening <NUM>. In suitable packages, the vent may be located in, for example, a top, a bottom, a front, a rear, a side, a lid, a cover, or a cap of the package. Pressure relief valve <NUM>, 10a may also be used on an interior surface <NUM> of package <NUM> in appropriate circumstances.

Referring now to <FIG> and <FIG>, components of embodiments of pressure relief valves <NUM>, 10a will be described. In the examples, valve <NUM>, 10a components may include a base <NUM> with a vent <NUM>, a dry strap <NUM> abutting the base <NUM> and covering (e.g., overlying) the vent <NUM>, a wetting fluid <NUM> between the base <NUM> and dry strap <NUM>, and a cover <NUM>. Textured surface <NUM> including wetting fluid reservoirs <NUM> may be on dry strap <NUM>, on base <NUM>, or on both dry strap <NUM> and base <NUM>. Valve 10a illustrated in <FIG> represents an example of a valve with textured surfaces <NUM>, 13a on both dry strap <NUM> and base 33a. Reservoirs <NUM> contribute to retention of wetting fluid <NUM> within valve <NUM> and valve 10a, minimizing or avoiding migration (i.e., "leaking") of wetting fluid <NUM> out of valve <NUM>, 10a. Valve <NUM>, 10a may include other structure as described herein.

Referring then to <FIG> and <FIG>, valve <NUM> may include a gas-impervious base <NUM> which may also be thought of as an outer layer in the examples. Base <NUM> should be of a gas-impervious material to block passage of any ambient air through base <NUM> and into package <NUM>. <FIG> illustrates another base 33a iteration used in connection with valve embodiment 10a. For simplicity and convenience, like reference numbers are used to indicate like parts of each base <NUM>, 33a. Each base <NUM>, 33a provides a type of platform on which pressure relief valve <NUM> may be constructed and which may be attached directly to package <NUM>, for example by means of adhesive <NUM> as described below. The term "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 <NUM>, 33a, a laminate of multiple joined-together layers, one or more layers with a filter element, or other supportive structure for valve <NUM>, 10a.

In the examples, base <NUM>, 33a may include a peripheral edge <NUM>, a first side <NUM>, and a second side <NUM>. Relative to the parts comprising pressure relief valve <NUM>, first side <NUM> can be considered an inner side while second side <NUM> can be considered an outer side. Exemplary base <NUM> (<FIG> and <FIG>) may be identical to base 33a (<FIG>) with the exception that first side <NUM> of base <NUM> lacks a textured surface <NUM> whereas base 33a includes a textured surface <NUM>.

In the examples, base <NUM>, 33a is generally flat, or planar, and may be made of a strip-type material. Referring to <FIG>, base <NUM>, 33a may have a width dimension identified by the character "W" and a length dimension identified by the character "L". Representative materials suitable for use as base <NUM>, 33a material can include polyethylene, polypropylene, and polyester. 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 <NUM>, 33a. Base <NUM>, 33a may have a thickness dimension between first and second sides <NUM>, <NUM> in the range of about <NUM> inches (i.e. <NUM>,<NUM>) to about <NUM> inches (i.e. <NUM>,<NUM>) for various iterations of valve <NUM>. As used herein, "about" means or refers to the value given ± <NUM>%.

As illustrated in the examples of <FIG>, <FIG>, and <FIG>, base <NUM> may include a vent <NUM>. Base 33a illustrated in <FIG> may include a vent <NUM> identical to that described in connection with valve <NUM> of <FIG>, <FIG>and it is to be understood that the description of vent <NUM> is applicable to valve 10a and base 33a. Vent <NUM> may be generally centrally disposed within peripheral edge <NUM> of base <NUM>, 33a and may extend entirely through base <NUM>, 33a, thereby allowing gas to pass through vent <NUM> and entirely through base <NUM>, 33a. In the examples, valve <NUM>, 10a would preferably be affixed to an exterior surface <NUM> of package <NUM> with vent <NUM> of base <NUM>, 33a over and in alignment with vent opening <NUM> in package <NUM>. According to these examples, vent <NUM> provides part of a passageway <NUM> for gas within package <NUM> to be directed through base <NUM>, 33a and into and through valve <NUM>, 10a.

Referring next to <FIG>, vent <NUM> shown with base <NUM> (and useful in base 33a) may function as a filter element <NUM>. A vent <NUM> in the form of a filter element <NUM> can block particulates (e.g., coffee <NUM>) from entering valve <NUM> and potentially interfering with complete closure and operation of valve <NUM>. Incomplete closure of valve <NUM> can allow ambient air to enter package <NUM> through valve <NUM>, potentially oxidizing and damaging coffee <NUM> or other material contained within package <NUM>.

Referring again to <FIG>, exemplary vent <NUM> is defined by aperture <NUM> and barrier <NUM> portions. In the examples, barrier portions <NUM> are all parts of base <NUM> (and base 33a) which are not aperture portions <NUM>. Barrier portions <NUM> may be continuous, gas-impermeable portions of base <NUM>, 33a which serve as a barrier to movement of any particulate substance (e.g., coffee <NUM>) through base <NUM>, 33a.

Referring again to <FIG>, aperture portions <NUM> preferably consist of plural small openings in base <NUM>, 33a. To avoid obscuring the drawings, just several of such small apertures are indicated by reference number <NUM>. In the examples of valve <NUM>, nine apertures <NUM> are illustrated. The nine apertures <NUM> are shown in three evenly-spaced rows and columns. Aperture portions <NUM> may be sized to block particles typical of those found in ground coffee <NUM> which may be about <NUM> or less in size. In other words, in certain embodiments barrier portions <NUM> defining apertures <NUM> therebetween may be spaced apart by about <NUM> inches (i.e. <NUM>,<NUM>) or less and apertures <NUM> of such type may be thought of as micro-apertures. Aperture portions <NUM> may be formed by any appropriate means, such as by laser drilling or punching.

It is to be understood that any suitable number, size, spacing, and arrangement of apertures may be utilized and the examples including nine apertures <NUM> are merely illustrative. For example, a single aperture could be provided. Spacing between plural apertures <NUM> could be more or less than <NUM> inches (i.e. <NUM>,<NUM>) to provide apertures of any desired area. Circles, chevrons, x-shaped apertures, and combinations of shapes and sizes of apertures <NUM> may be implemented. Even spacing is optional as apertures <NUM> may be randomly distributed across base <NUM>, 33a.

In a further embodiment, a base (e.g., base <NUM> or 33a) 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 <NUM> or along a first <NUM> or second side <NUM> of base <NUM> forming a part of base <NUM>. Addition of a separate adhesive may be implemented as appropriate to adhere such membrane to valve <NUM> and to secure valve <NUM> to a release liner, such as release liner <NUM>.

A further benefit of a vent <NUM> comprising very small apertures <NUM> (e.g., micro-apertures less than about <NUM> inches (i.e. <NUM>) across) defined by barrier portions <NUM> or with a vent of flashspun high-density polyethylene fibers is that such a vent <NUM> may limit and restrict any migration of wetting fluid <NUM> through apertures <NUM>. In other words, small openings (e.g., apertures <NUM>) can contribute to avoidance of "leakage" of wetting fluid <NUM> from valve <NUM>.

Referring now to <FIG> and <FIG>, adhesive <NUM> may be provided on base <NUM>, 33a second side <NUM> (i.e., an outer side) to both removably mount base <NUM>, 33a and valve <NUM>, 10a on release liner <NUM> (<FIG>) and to permanently attach base <NUM>, 33a and pressure relief valve <NUM>, 10a to a package <NUM> (<FIG>).

Referring once again to <FIG> and <FIG>, adhesive <NUM> may be deposited across base <NUM>, 33a second side <NUM>. As best shown in <FIG>, adhesive <NUM> may be spaced from apertures <NUM> with a circular inner edge <NUM> surrounding apertures <NUM> and vent <NUM>. Edge <NUM> and adhesive <NUM> block any lateral gas or air movement between valve <NUM>, 10a and package <NUM>. Adhesive <NUM> may be about <NUM> inches (i.e. <NUM>,<NUM>) to about <NUM> inches (i.e. <NUM>,<NUM>) in thickness. By way of example, types of adhesives which may be utilized include pressure-sensitive adhesives (PSAs), heat-activated adhesives, ultra-violet cured adhesives, water-based adhesives, solvent-based adhesives, and rubber-based adhesives.

In embodiments, selection of an adhesive <NUM> which is resistant to degradation and loss of tack (i.e., tack killing) resulting from contact with wetting fluid <NUM> is desirable and can improve adhesion of valve <NUM>, 10a to a surface such as release liner <NUM> and/or a wall <NUM> of package <NUM>. Oleophobic adhesives are examples of adhesives <NUM> that have oil-resistant characteristics and which have excellent tack properties notwithstanding contact with oil-based fluids such as silicone oil, graphite impregnated oil, food grade oil, and food grade silicone grease commonly used as wetting fluids <NUM>. Acrylic adhesives <NUM> are particularly preferred because they can be selected and/or formulated to have the desired oleophobic properties. Therefore, selection of an adhesive with oleophobic properties represents another aspect of the invention which, in combination with the reservoirs <NUM>, can contribute to improved performance of valves <NUM>, 10a.

Referring next to <FIG> and <FIG>, dry strap <NUM> enables pressure relief valve <NUM>, 10a to be placed in a closed state and, alternatively, in an open state by allowing gas to flow through vent <NUM> along gas passageway <NUM> or by covering vent <NUM> blocking flow of ambient air or other gas therethrough. Referring to <FIG>, <FIG>, <FIG>, and <FIG>, those figures illustrate valve <NUM>, 10a in a closed state with dry strap <NUM> overlying vent <NUM>. <FIG> and <FIG> are examples of valve <NUM> in an exaggerated open state with dry strap <NUM> spaced apart from at least portions of base <NUM> and vent <NUM>. In the closed state (<FIG>, <FIG>, <FIG>, and <FIG>), dry strap <NUM> is in a first position blocking entry of ambient air into valve <NUM> and package <NUM>. In the open state (<FIG> and <FIG>), dry strap <NUM> is in a further position, or positions, in which valve <NUM> permits one-way gas flow out from package <NUM>, through pressure relief valve <NUM>, along gas flow path <NUM> and out to the ambient air and surrounding environment. Dry strap <NUM> may, for example, function by undulating movement permitting separate gas bubbles to escape package <NUM> through valve <NUM>. Surface tension provided by wetting fluid <NUM> holds dry strap <NUM> onto base <NUM>, facilitating the air-tight seal blocking entry of ambient air through valve <NUM> and into package <NUM>. It is to be understood that dry strap <NUM> of valve 10a has the same structure and operation as described in connection with valve <NUM>.

Pressure relief valves <NUM>, 10a may be engineered to predictably and accurately open and close based on a known, predetermined pressure differential between pressure inside package <NUM> and pressure outside package <NUM>. 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 <NUM>, 10a may be designed to open with any desired pressure differential. By way of example only, pressure relief valve <NUM>, 10a may be designed to have a targeted opening pressure when the pressure inside package <NUM> exceeds pressure external to package <NUM> by <NUM> psig (pounds per square inch gauge) (i.e. <NUM>,<NUM> Pa) or less. Pressure relief valve <NUM>, 10a may be designed to close when the targeted pressure inside package <NUM> exceeds pressure outside package <NUM> by <NUM> psig (i.e. <NUM>,<NUM> Pa) or more. Other opening and closing pressures may be utilized and the foregoing are merely non-limiting examples. Opening and closing pressures can be adjusted, for example, by increasing or, alternatively, decreasing the area of aperture(s) <NUM> comprising vent <NUM> or by increasing or, alternatively, decreasing the viscosity of wetting fluid <NUM>, or by selection of materials used for dry strap <NUM> and cover <NUM>.

Examples of a dry strap <NUM> embodiment which may be used with valve <NUM>, 10a will now be described in connection with <FIG> and <FIG>. In the examples, dry strap <NUM> overlies vent <NUM> between base <NUM>, 33a and cover <NUM>. Dry strap <NUM> may have a first, or outer side, side <NUM> facing toward cover <NUM> and a second, or inner, side <NUM> facing toward base <NUM>, 33a first side <NUM>.

Referring to <FIG>, <FIG>, and <FIG>, dry strap <NUM> may have a width dimension W between opposite sides <NUM>, <NUM> of dry strap <NUM> which is less than the width dimension W of base <NUM>, enabling cover <NUM> to be secured to base <NUM>, 33a on opposite sides <NUM>, <NUM> of dry strap <NUM> by adhesive <NUM> as described below. Dry strap <NUM> may have outer edges <NUM>, <NUM> defining a length dimension L therebetween which is the same as the length L dimension of base <NUM>, 33a (<FIG> and <FIG>). Preferably, each outer edge <NUM>, <NUM> of dry strap <NUM> extends all the way to meet peripheral edge <NUM> of base <NUM>, 33a. As illustrated in <FIG> and <FIG>, second side <NUM> of dry strap <NUM> may define and lie in a plane <NUM> when valve <NUM> is in the closed state or position.

In the examples, adhesive <NUM> may join dry strap <NUM> to cover <NUM> and may join cover <NUM> ends <NUM>, <NUM> outboard of dry strap <NUM> sides <NUM>, <NUM> to corresponding spaced apart attachment regions <NUM>, <NUM> of base <NUM>. Because cover <NUM> is unjoined to base <NUM> between cover ends <NUM>, <NUM> and attachment regions <NUM>, <NUM>, cover <NUM> is permitted to flex and to move at least partially away from base <NUM> first side <NUM> (<FIG> and <FIG>) along this unjoined cover <NUM> region <NUM> when valve <NUM> is in the open state to permit gas flow out of valve <NUM> and along gas flow path <NUM>. Such flexing may be a slight undulating, or "burping", movement of dry strap <NUM> with portions second side of dry strap <NUM> spaced from plane <NUM> sufficiently to accommodate passage of gas bubbles between base <NUM>, 33a and dry strap <NUM>.

Referring to <FIG>, <FIG>, and <FIG>, gas flow path <NUM> represented by the arrows <NUM> may extend through vent <NUM> under dry strap <NUM> and may be bounded laterally by ends <NUM>, <NUM> of cover <NUM>. Gas flow path <NUM> channels and directs gas outflow through valve <NUM>.

Dry strap <NUM> may have other shapes and configurations. For example, dry strap <NUM> may have a width dimension between sides <NUM>, <NUM> and a length dimension between edges <NUM>, <NUM> which are identical to the length dimension and width dimension of base <NUM>, 33a and cover <NUM> with each outer side <NUM>, <NUM> and edge <NUM>, <NUM> of dry strap <NUM> extending all the way to meet the peripheral edge <NUM> of base <NUM>, 33a and the peripheral edge of cover <NUM> so that each of base <NUM>, 33a, dry strap <NUM> and cover <NUM> have the same area. In such examples, base <NUM>, 33a, dry strap <NUM>, and cover <NUM> may be joined together by, for example, sonic welding of cover <NUM> ends <NUM>, <NUM> to corresponding spaced apart attachment regions <NUM>, <NUM> of base <NUM>, 33a.

Further, base <NUM>, 33a, dry strap <NUM>, and cover <NUM> may have shapes other than the rectangular shapes illustrated. By way of example only, base <NUM>, 33a, dry strap <NUM>, and cover <NUM> may have circular shapes, or hexagonal shapes, or polygonal shapes.

As illustrated in <FIG>, dry strap <NUM> may be a single piece of material. By way of further non-limiting example, dry strap <NUM> may be a plural-part dry strap, for example, as described in commonly-owned <CIT>.

Referring to <FIG>, dry strap <NUM> may be of a strip-type material. Dry strap <NUM> most preferably is of a gas-impervious material to avoid passage of ambient air through dry strap <NUM> and into package <NUM>. Dry strap <NUM> may also be of a material which provides a vapor barrier preventing humidity in ambient air from entering package <NUM>. Representative materials suitable for use as dry strap <NUM> material can include polyethylene, polypropylene, polyester such as PET, or other suitable material. As described below, dry strap <NUM> may be chemically etched or otherwise treated or processed to provide textured surface <NUM> on the second side <NUM> of dry strap <NUM> facing base <NUM>, 33a. Dry strap <NUM> may have a thickness dimension between first side <NUM> (i.e., the outer side) and second side <NUM> (i.e., the inner side) in the range of about <NUM> inches (i.e. <NUM>,<NUM>) to about <NUM> inches (i.e. <NUM>,<NUM>) for various iterations of valves <NUM>.

In the examples and referring to <FIG> and <FIG>, valve <NUM> cover <NUM> overlies base <NUM>, 33a, 33b and dry strap <NUM>. Cover <NUM> may be attached to dry strap <NUM> and base <NUM>, 33a for example, by means of adhesive <NUM>. In the examples, cover <NUM> includes peripheral edge <NUM>, a first side <NUM> and a second side <NUM>. Relative to base <NUM>, 33a and dry strap <NUM>, first side <NUM> may be considered an outer side, while second side <NUM> of cover <NUM> facing toward dry strap <NUM> and base <NUM>, 33a can be considered an inner side.

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

Cover <NUM> may have a width dimension W and length dimension L (<FIG>, <FIG>, <FIG>) which approximate the width and length dimensions of base <NUM>, 33a. Cover <NUM> peripheral edge <NUM> may be coextensive with base <NUM>, 33a peripheral edge <NUM> as illustrated in <FIG>, <FIG>, and <FIG>. Dry strap edges <NUM>, <NUM> may extend to respective opposite edges of both cover <NUM> and base <NUM>, 33a.

Cover <NUM> may have a thickness dimension between first and second sides <NUM>, <NUM> in the range of about <NUM> inches (i.e. <NUM>,<NUM>) to about <NUM> inches (i.e. <NUM>,<NUM>) for various iterations of valve <NUM>. Cover <NUM> most preferably is of a gas-impervious material to prevent passage of any ambient air and moisture through cover <NUM> and into valve <NUM> and possibly into package <NUM>. Representative materials suitable for use as cover <NUM> material can include polyethylene, polypropylene, polyester such as PET, or other suitable material.

Referring to <FIG> and as previously described, ends <NUM>, <NUM> of cover <NUM> on the second side <NUM> of cover <NUM> may be joined to attachment regions <NUM>, <NUM> of base <NUM>, 33a by adhesive layer <NUM> and may be unattached to base <NUM>, 33a therebetween (i.e., unjoined region <NUM>) allowing cover <NUM> to flex slightly away from base <NUM>, 33a so that gas can flow out of valve <NUM> along gas flow path <NUM> as previously described. Adhesive <NUM> may be the same type of adhesive as used for adhesive layer <NUM> on base <NUM>, 33a second side <NUM>. Cover <NUM> may be joined to base <NUM>, 33a attachment regions <NUM>, <NUM> by means other than adhesive <NUM> such as the sonic welding previously described.

Referring to the examples of <FIG>, <FIG>, and <FIG>, valves <NUM>, 10a of the type described herein are engineered for use with a wetting fluid <NUM> for the purpose of improving sealing closure of dry strap <NUM> against base <NUM>, 33a to completely block ambient air entry into valve <NUM>, 10a. In the examples of <FIG> and <FIG> and <FIG>, wetting fluid <NUM> wets first side <NUM> (i.e., the inner side) of base <NUM>, 33a and second side <NUM> (i.e., the inner side) of dry strap <NUM> providing a surface tension which improves the aforementioned sealing closure of base <NUM>, 33a and dry strap <NUM> around vent <NUM>. Wetting fluid <NUM> may be deposited on first side <NUM> of base <NUM>, 33a under dry strap 37and completely around vent <NUM> and on barrier portions <NUM> between apertures <NUM>. Wetting fluid <NUM> plates out onto at least first side (i.e., the inner side) <NUM> of base <NUM>, 33a and second side <NUM> (i.e., the inner side) of dry strap <NUM> to wet and provide the surface tension between base <NUM>, 33a and dry strap <NUM>, improving the closure of valve <NUM>, 10a. By way of non-limiting example, about <NUM>µL to about <NUM>µL of wetting fluid may be used for a valve having an area of about <NUM><NUM>.

As an example only, about <NUM>µL of wetting fluid <NUM> may be applied between dry strap <NUM> and base <NUM>, 33a for a valve <NUM>, 10a according to the invention having an area of about <NUM><NUM>. As described herein, the reservoir <NUM> structure of valve <NUM> provides space for wetting fluid <NUM> to reside within valve <NUM>, 10a so that it does not migrate out from between dry strap <NUM> and base <NUM>, 33a and onto release liner <NUM>, package <NUM>, adhesive <NUM> on second side <NUM> of base <NUM>, 33a and onto exterior surfaces of valve <NUM>.

As a result of the invention, opportunities exist to utilize relatively less wetting fluid <NUM> as compared with valves not including reservoirs <NUM>. By way of example only, a valve <NUM>, 10a with a base <NUM>, 33a having an area of <NUM><NUM> can utilize approximately <NUM>µL less wetting fluid <NUM> than a valve not including reservoirs <NUM>. Any opportunity to utilize less wetting fluid <NUM> is desirable because there is less wetting fluid <NUM> to potentially migrate away from valve <NUM>, 10a.

The wetting fluid <NUM> imparts excellent performance benefits to the valve <NUM>, 10a, including providing an excellent air-tight seal of the valve <NUM>, 10a while allowing very delicate (i.e., quite small) opening and closing movements of the valve <NUM>, 10a, including undulating (i.e., burping) movement enabling gas bubble flow between base <NUM>, 33a and dry strap <NUM>. Valves <NUM>, 10a including a wetting fluid <NUM> can be engineered to open and close at predictable, low pressures as described herein.

Examples of wetting fluid <NUM> may be silicone oil, a graphite impregnated oil, a food grade oil, food grade silicone grease, or other viscous fluid as previously described.

Wetting fluid <NUM> may be applied to valve <NUM>, 10a at any suitable point including during valve <NUM>, 10a manufacture or as the pre-manufactured valve is applied to the package (e.g., package <NUM>). An advantage of valves <NUM>, 10a is that the wetting fluid <NUM> may be precisely applied to the second side <NUM> of a running web of material used to provide dry strap <NUM> and/or the first side <NUM> of a running web of material used to provide base 33a during a running converting process in which the running webs are joined together to form valve <NUM>, 10a. Precise placement of wetting fluid <NUM> onto reservoirs <NUM> where the wetting fluid <NUM> can be held as the webs forming the base <NUM>, 33a, dry strap <NUM>, and cover <NUM> are joined together during a running conversion process used to make valves <NUM>, 10a is advantageous because it enables an accelerated manufacturing process while lessening any risk of wetting fluid <NUM> leaking from valve <NUM>, 10a.

Referring to <FIG> and <FIG>, valve <NUM>, 10a may include one or more textured surface <NUM> with reservoir <NUM> structure provided to hold wetting fluid <NUM> to limit or avoid migration (i.e., "leaking") of wetting fluid <NUM> out and away from valve <NUM>, 10a. As used herein, the term "textured" means or refers to a rough or uneven surface or consistency. Such roughness or unevenness providing the texture forming the reservoirs <NUM> may be on a microscopic level (i.e., very small). In certain examples, reservoirs <NUM> themselves are not visible to the naked eye but the textured surface <NUM> may provide a matte-finish in which light is scattered rather than reflected providing a relatively dull appearance to the naked eye. In the examples and as will be described herein, a textured surface <NUM> may include many reservoirs <NUM>. As already stated, for brevity and convenience, reference number <NUM> is used to indicate representative ones of the reservoirs <NUM>.

A textured surface <NUM> may be provided at various locations with respect to valve <NUM>, 10a. As illustrated in the valve <NUM> embodiment of <FIG> and <FIG>, dry strap <NUM> second side <NUM> (i.e., the inner side) facing base <NUM>, 33a first side (i.e., the inner side) <NUM> may include the textured surface <NUM>. In such valve <NUM> and as illustrated in <FIG>, base <NUM> may lack a textured surface <NUM>. In other embodiments, textured surface <NUM> may be on the first side <NUM> (i.e., the inner side) of base <NUM> and not on dry strap <NUM> second side facing base <NUM>. In still other examples and as illustrated in <FIG>, both dry strap <NUM> second side <NUM> and base 33a first side <NUM> (which faces dry strap <NUM>) may include a textured surface <NUM>. Such textured surface <NUM> may cover some, or all, of dry strap <NUM> second side <NUM> (i.e., the inner side) and/or base first side <NUM> (i.e., the inner side) as desired for wetting fluid <NUM> storage capacity.

<FIG> are micrographs provided as comparative examples of film strips <NUM>, <NUM> with strip <NUM> having a non-textured surface <NUM> (<FIG>) and strip <NUM> having a textured surface <NUM> (<FIG> each illustrate a sample polyethylene terephthalate strip (PET) <NUM>, <NUM> having a thickness of about <NUM> inches (i.e. <NUM>,<NUM>). Each micrograph was captured using an Optical Gauging Products (OGP) camera at an <NUM>-x zoom. <FIG> is illustrative of a textured surface <NUM> of a microscopic type.

Referring first to <FIG>, it can be seen that strip (e. g, a type of film) <NUM> illustrated therein has a surface <NUM> which appears visually to be a smooth surface in the micrograph. The PET material shown in <FIG> is of the type commonly used in conventional one-way pressure relief valves. The surface <NUM> of <FIG> appears visually to be smooth because surface <NUM> lacks a textured surface <NUM> and lacks reservoirs <NUM>. If, as in conventional valves, dry strap <NUM> second side <NUM> (i.e., the inner side) and/or base <NUM>, 33a first side <NUM> (i.e., the inner side) are of the smooth surface <NUM> type shown in <FIG>, then any wetting fluid <NUM> between dry strap <NUM> and base <NUM>, 33a could under certain circumstances migrate out of the valve causing the aforementioned performance problems.

<FIG> illustrates an example of a strip (e. g, a type of film) <NUM> according to the invention with a textured material <NUM>. In the example of <FIG>, the polyethylene terephthalate strip <NUM> has a three-dimensional textured surface <NUM> unlike the example of <FIG>. Such textured surface <NUM> of strip <NUM> may be considered "roughened" on a microscopic level relative to smooth surface <NUM> of the strip <NUM> illustrated in <FIG>. The three-dimensional textured surface illustrated in <FIG> provides reservoirs <NUM>. The textured surface <NUM> of strip <NUM> illustrated in <FIG> may be implemented as second side <NUM>, of dry strap <NUM> (<FIG> and <FIG>), as first side <NUM> of base <NUM>, or as both second side <NUM> of dry strap <NUM> and first side <NUM> of base <NUM> (<FIG>).

Textured surface <NUM> illustrated in <FIG> may be comprised of outer surface portions <NUM> and inner surface portions <NUM> (i.e., that is inner relative to outer surface portions <NUM>). In the examples, outer surface portions <NUM> provide "protrusions" of textured surface <NUM> while inner surface portions provide "recesses" in textured surface <NUM>. At least the inner surface portions <NUM> define wetting fluid reservoirs <NUM> in the examples. Outer surface portions <NUM> may also define reservoirs <NUM>, especially in combination with inner surface portions <NUM>.

<FIG> schematically illustrate representative microscopic outer surface portions <NUM> and inner surface portions <NUM> of textured surfaces <NUM> and 13a. Outer surface portions <NUM> and inner surface portions <NUM> of textured surface <NUM> may be irregular, or random, as illustrated in <FIG>. By way of example only, the distance between the outermost portion of the outer surface portions <NUM> and the innermost portion of the inner surface portions <NUM> may be in the range of about <NUM> to about <NUM> with about <NUM> to about <NUM> being a preferred range for certain iterations of the valve <NUM>, 10a.

Textured surface <NUM> and outer and inner surface portions <NUM>, <NUM> may be formed by various techniques. One such technique is through a chemical etching process. The chemical etching may produce a textured surface <NUM> with a matte-finish. Other techniques of forming textured surface <NUM> include plasma treating and laser ablading. Formation of textured surface <NUM> by means of plasma treating and laser ablading also yields a matte finish representative of the outer and inner surface portions <NUM>, <NUM> forming reservoirs.

The matte finish of the textured surface <NUM> may be quantified by reference to its Ra value. As is known, an Ra value is a value representing the average of a set of individual measurements of surface peaks and valleys, in other words an arithmetical mean roughness of a surface. (See ASME B46. <NUM>) Such roughness provides reservoirs <NUM>. In embodiments, a surface roughness having matte finish with an Ra value of about <NUM> to about <NUM> may be implemented.

Valve <NUM> illustrated in <FIG>, represents an embodiment in which the second <NUM>, or inner side, of dry strap <NUM> is provided with reservoirs while base <NUM> first <NUM>, or inner side, is not. Valve 10a illustrated in <FIG> represents an embodiment in which both the second side <NUM> of dry strap <NUM> and the first side <NUM> of base 33a are provided with textured surfaces <NUM>, 13a including reservoirs <NUM>. An embodiment wherein just the first side <NUM> of the base <NUM> has a textured surface <NUM> and the second side <NUM> of the dry strap <NUM> does not include a textured surface <NUM> is also within the scope of the invention. Such an embodiment may simply be a reversed version of the valve <NUM> illustrated in <FIG>.

Referring further to <FIG>, outer surface portions <NUM> defining reservoirs <NUM> may be adjacent an opposite surface of valve <NUM>, 10a, such as base <NUM>, 33a first side <NUM> or dry strap <NUM> second side <NUM>. Inner surface portions <NUM> would be spaced from such opposite surfaces of valve <NUM>, 10a. In the examples, the spaces, voids, or small pockets defined by outer surface portions <NUM> and inner surface portions <NUM> represent the reservoirs <NUM> purposed to hold wetting fluid <NUM>. The outer surface portions <NUM> and inner surface portions <NUM> forming reservoirs <NUM> define a volume for holding wetting fluid <NUM>. Unlike conventional valves, if dry strap <NUM> second side <NUM> (i.e., the inner side) and/or base <NUM>, 33a first side <NUM> (i.e., the inner side) are of the textured surface material <NUM>, 13a, then any wetting fluid <NUM> between dry strap <NUM> and base <NUM>, 33a can be held in reservoirs <NUM> thereby limiting or stopping migration of wetting fluid <NUM> out from between dry strap <NUM> and base <NUM>, 33a avoiding the previously described problems caused by leakage of wetting fluid <NUM> from valve <NUM>.

Reservoirs <NUM> are particularly effective in holding wetting fluid <NUM> in excess of that required to provide the surface tension between dry strap <NUM> and base <NUM>, 33a. Holding of excess volumetric amounts of wetting fluid <NUM> within reservoirs <NUM> is desirable, for example, if valves <NUM> are to be stored for any extended period of time before application to package <NUM>. This is because wetting fluid <NUM> could evaporate and the presence of excess wetting fluid <NUM> ensures that sufficient wetting fluid <NUM> is available to plate out between dry strap <NUM> and base <NUM>, 33a ensuring proper valve <NUM> operation.

<FIG> illustrate other iterations of textured surfaces 13b, 13c, 13d, 13e which may be used in embodiments of the inventive valve. <FIG> illustrate that microscopic outer surface portions <NUM> and inner surface portions <NUM> providing textured surfaces 13b, 13c, 13d, 13e may have reservoirs <NUM> with a repeated, identical pattern. <FIG> illustrate that textured surfaces 13b and 13c may comprise <NUM>° (<FIG>) or <NUM>° (<FIG>) hexagonal reservoirs <NUM>. By way of further example, <FIG> illustrate that textured surfaces 13d and 13e may comprise tri-helical (<FIG>) or <NUM>° (<FIG>) channel reservoirs <NUM>. Outer and inner surfaces <NUM>, <NUM> defining reservoirs <NUM> of <FIG> may be created by any suitable means, including by laser etching. Combinations of any of the aforementioned textured surfaces may be implemented to provide reservoirs capable of holding wetting fluid <NUM>. <FIG> collectively illustrate that reservoirs <NUM> may be of many different shapes and sizes consistent with the invention.

In embodiments, the viscosity of the wetting fluid <NUM> (e.g., silicone oil, graphite impregnated oil, food grade oil, silicone grease, or other viscous fluid) may be engineered and/or selected to improve retention of wetting fluid <NUM> within reservoirs <NUM> to further reduce or eliminate migration of wetting fluid <NUM> out and away from valve <NUM>. A higher viscosity wetting fluid <NUM> has a lower flow rate and is less likely to migrate out of valve <NUM>. An example of a viscosity range of wetting fluid <NUM> may be about <NUM> centipoise ("cps") to about <NUM> cps, with a more preferred range being about <NUM> cps to about <NUM> cps, and a viscosity of about <NUM> cps being particularly effective. Food grade silicone grease used as a wetting fluid in some applications can have a viscosity of <NUM>,<NUM> centipoise. The viscosity of wetting fluid <NUM> can also be selected to adjust and select the target opening pressure of valve <NUM>. The pressure will be greater with more viscous wetting fluids <NUM> and vice-versa. Wetting fluid <NUM> viscosity in combination with reservoirs <NUM> and/or sizing of apertures <NUM> can enhance retention of wetting fluid <NUM> within valve <NUM>, 10a.

Referring to <FIG>, <FIG>, and <FIG>, valve <NUM> may optionally include bumpers <NUM>, <NUM> (also sometimes referred to as "rails") on first side <NUM> (i.e., outer side) of cover <NUM>. Bumpers <NUM>, <NUM> may be secured to cover <NUM> by an adhesive <NUM>. Adhesive <NUM> may be identical to the adhesive provided as adhesive layers <NUM> and <NUM> as previously described. If provided, bumpers <NUM>, <NUM> serve to space dry strap <NUM> from adjacent packages and objects avoiding application of force to dry strap <NUM> that could interfere with movement of dry strap <NUM> to the open position of <FIG> and <FIG> and providing for improved valve <NUM>, 10a operation.

Referring now to <FIG>, an exemplary series of four pressure relief valves, each indicated as <NUM> for convenience, are shown mounted on a fragment of a release liner <NUM>. Valves 10a may each be mounted to release liner <NUM> in an identical manner to that shown in <FIG>. An advantage of improved valves <NUM>, 10a is that contact between wetting fluid <NUM> and release liner <NUM> is limited or eliminated.

Valves <NUM> may be removed from release liner <NUM> and may be attached to a package, such as package <NUM> of <FIG>. Release liner <NUM> may be of a material to which adhesive <NUM> can temporarily attach valves <NUM> without damaging adhesive <NUM>. Release liner <NUM> carries pressure relief valves <NUM> until the valves <NUM> are removed during the process of attaching valves <NUM> to packaging, for example by automated application equipment. As illustrated in <FIG>, valves <NUM> may be conveniently spaced apart at regular intervals along release liner <NUM>, as for example, at a one inch interval between centers, although the repeat spacing is also dependent on the packaging application.

In certain "green" applications in which eco-friendly materials are required, it may be desirable for pressure relief valve <NUM>, 10a to be constructed of biodegradable materials, that is materials which will decompose when in a landfill. Where biodegradability is desired, base <NUM>, 33a, dry strap <NUM>, cover <NUM> and other valve <NUM> components may be made of polylactic acid, cellulose acetate, or other compostable materials.

Referring to <FIG> and <FIG>, operation of valve examples <NUM>, 10a will now be described. In operation, pressure relief valve <NUM>, 10a is initially in a first, or closed, state similar to that shown in <FIG>, <FIG>, <FIG>, and <FIG>. In this closed state of the examples, dry strap <NUM> second side <NUM> may abut base <NUM>, 33a first side <NUM> with wetting fluid <NUM> surrounding vent <NUM>. Wetting fluid <NUM> provides surface adhesion between dry strap <NUM> and base <NUM>, 33a and cover <NUM> provides a force which serves to urge dry strap <NUM> sealingly against base <NUM>, 33a blocking movement of gas through vent <NUM> and preventing ambient air from entering package <NUM>, thereby preserving the freshness of coffee <NUM> or other material inside package <NUM>.

In the examples of pressure-relief valve <NUM>, 10a, when pressure inside package <NUM> builds to exceed the predetermined and known target pressure, valve <NUM>, 10a will at least partially open to allow gas to escape from package <NUM> and through valve <NUM>, 10a (via gas passageway <NUM>). In the embodiments of valves <NUM>, 10a, force applied through vent <NUM> and against dry strap <NUM> causes at least partial separation of dry strap <NUM> from base <NUM>, 33a first surface <NUM> so that valve <NUM>, 10a is in the open state such as in the examples of <FIG> and <FIG> as previously described. For both valves <NUM>, 10a, flexure of cover <NUM> may allow complete, partial, or undulating separation of plural-part dry strap <NUM> from base <NUM>, 33a to open gas flow path <NUM>, allowing gas to escape from package <NUM> when valve <NUM>, 10a is in the open state. Most typically, there will be a gradual undulating movement of dry strap <NUM> as individual gas bubbles pass between dry strap <NUM> and base <NUM>, 33a.

As illustrated in the examples of <FIG>, each textured surface <NUM> and fluid reservoirs <NUM> therein may provide storage spaces for wetting fluid <NUM>. Wetting fluid <NUM> that might otherwise migrate out of valve <NUM>, 10a would be retained in reservoirs <NUM> avoiding leakage. Reservoirs <NUM> further provide a means to reduce pressure on wetting fluid <NUM> applied by dry strap <NUM> and base <NUM>, 33a that might otherwise accelerate wetting fluid <NUM> flow out of valve <NUM>, 10a. Textured surface <NUM> and reservoirs <NUM> alone mitigate or eliminate wetting fluid <NUM> leakage from valve <NUM>, 10a.

An advantage of certain valve embodiments <NUM>, 10a is that reservoirs <NUM> provide an opportunity to utilize a volumetric lesser amount of wetting fluid <NUM> as compared with conventional valves lacking reservoirs. Relatively less wetting fluid <NUM> may be utilized because the wetting fluid <NUM> does not migrate out from the valve. Accordingly, excessive amounts of wetting fluid <NUM> provided in anticipation of leakage are unnecessary. Implementation of a lesser amount of wetting fluid <NUM> is desirable because the risk of leakage is minimized by the presence of lesser amounts of the wetting fluid <NUM>.

Other optional features of valve <NUM>, 10a as described herein may facilitate improved retention of wetting fluid <NUM> within valve <NUM>, 10a or may serve to mitigate the effect of any potential leakage of wetting fluid <NUM>. For instance, selection of an adhesive <NUM>, <NUM>, <NUM> with oleophobic properties which is resistant to contamination by wetting fluid <NUM> will further avoid any loss of adhesion should wetting fluid <NUM> come into contact with such adhesive <NUM>, <NUM>, <NUM>. By way of further example, sizing of apertures <NUM> with small area sizes may serve to limit or restrict movement of wetting fluid <NUM> through those apertures <NUM> and through base <NUM>, 33a. Limiting of wetting fluid <NUM> migration through apertures <NUM> avoids or minimizes any contamination of adhesive <NUM> and lessening of adhesion holding valve <NUM>, 10a on release liner <NUM> or on package <NUM>. As yet another optional improvement, wetting fluid <NUM> viscosity can be engineered to lessen or slow the flow of wetting fluid <NUM> out of valve <NUM> and onto second side <NUM> of cover <NUM> or package <NUM> exterior surface <NUM>. A greater viscosity would limit the flow of wetting fluid <NUM>. Valve <NUM>, 10a including textured surfaces <NUM> alone is sufficient to limit or eliminate migration of wetting fluid <NUM> out from valve <NUM>, 10a. Implementation of any of the aforementioned optional features may lead to enhanced operation in certain embodiments and applications.

As illustrated in <FIG> and <FIG>, an increase in differential pressure within package <NUM> above ambient pressure by a predetermined and known target pressure causes the previously closed valve <NUM>, 10a to open and to enter the open state. As previously described, the flexure of cover <NUM> and dry strap <NUM> may be of an undulating-type or burping-type, permitting single bubbles of gas to escape from package <NUM> through valve <NUM>. Such undulating movement would result from portions of dry strap <NUM> remaining in sealing contact with base <NUM>, 33a (with sealing improved by surface tension provided by wetting fluid <NUM>) while there is separation between dry strap <NUM> and base <NUM>, 33a to accommodate a bubble of gas therebetween.

When the differential pressure within package <NUM> decreases below a predetermined and known target pressure, cover <NUM> applies a force as it returns to its original position. In the embodiments of valves <NUM>, 10a, the force causes dry strap <NUM> to be relocated fully against base <NUM>, 33a with wetting fluid <NUM> plated out therebetween, closing vent <NUM> and returning pressure relief valve <NUM> to the closed state of <FIG>, <FIG>, <FIG>, and <FIG>.

The process of opening and closing pressure relief valve <NUM>, 10a is repeated when differential pressure inside package <NUM> again exceeds the target opening pressure and can continue until all of the coffee <NUM> or other gas-producing material is removed from package <NUM>.

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.

Claim 1:
A pressure relief valve (<NUM>, 10a) with wetting fluid reservoirs (<NUM>) comprising:
• a base (<NUM>, 33a) having a first side (<NUM>), a second side (<NUM>), an area, a peripheral edge (<NUM>), and a vent (<NUM>) extending entirely through the base (<NUM>, 33a);
• a cover (<NUM>) overlying the base (<NUM>, 33a), the cover (<NUM>) having a first side (<NUM>), a second side (<NUM>), an area, a peripheral edge (<NUM>), and opposite end portions secured with respect to the base (<NUM>, 33a);
• a dry strap (<NUM>) between the base (<NUM>, 33a) and the cover (<NUM>) overlying the entire vent (<NUM>) and having a second side (<NUM>) facing and at least partially abutting the first side (<NUM>) of the base (<NUM>, 33a); and
• a wetting fluid (<NUM>) disposed within the plurality of the reservoirs (<NUM>) and between the dry strap (<NUM>) and the base (<NUM>, 33a) entirely around the vent (<NUM>);
wherein the pressure relief valve (<NUM>, 10a) with the wetting fluid reservoirs (<NUM>) further comprises at least one microscopically textured surface (<NUM>) on the second side (<NUM>) of the dry strap (<NUM>) facing the base (<NUM>, 33a), or on the first side (<NUM>) of the base (<NUM>, 33a) facing the dry strap (<NUM>), or on the both the first side (<NUM>) of the base (<NUM>, 33a) and the second side (<NUM>) of the dry strap (<NUM>), the at least one microscopically textured surface (<NUM>) defining the plurality of fluid-holding reservoirs (<NUM>) therein.