Patent Publication Number: US-2009230081-A1

Title: Vented screwcap closure with diffusive membrane liner

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority from U.S. Provisional Patent Application No. 61/036,043, filed Mar. 12, 2008 and U.S. Provisional Patent Application No. 61/107,992, filed Oct. 23, 2008, the contents of which are incorporated herein by reference in its entirety. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to closures for bottles. More particularly, the invention relates to screw cap closures with oxygen permeability characteristics for wine bottles. 
     BACKGROUND OF THE INVENTION 
     Alongside winemaking, wine bottling technology has evolved over the past several hundred years. The winemaking industry has relied on the use of cork, which allows small amounts of oxygen through, as a sealing medium for wine bottles in the wine aging process. Oxygen that permeates through a wine bottle&#39;s cork seal is “consumed” by the bottled wine through the formation of acetaldehyde, which serves as a linking molecule between monomers. This process helps to stabilize longer chains of tannins, resulting in a smoother tasting wine over time. 
     The use of cork as a wine bottle sealing medium, however, suffers from several deficiencies. For one thing, the variability in natural cork bark, from which cork is made, results in variability in the rate of oxidation of wines in different bottles and consequently, variability in taste across bottles. In addition, cork contains a chemical known as 2,4,6 tricholoroanisole (TCA), a product of fungi that live in natural cork. When 2,4,6 TCA is released into wine, an unwelcome aroma is created. In small amounts, 2,4,6 TCA mutes the wine&#39;s aromatics but may completely ruin the wine in larger amounts. Excessive release of 2,4,6 TCA affects 2% to 5% of all corks. Furthermore, cork suffers from structural defects that include crumbling, breaking, and seepage, and requires the use of a tool (e.g., corkscrew) for removal from the wine bottle. Moreover, it is difficult to reseal a cork-sealed wine bottle without the use of additional devices. 
     Several attempts have been made to introduce wine bottle closure products that aim to rectify some or all of the above deficiencies. These products include: synthetic cork, screw caps, Vino-Lock (a glass stopper with a silicone seal), Zork (a peel-off plastic closure), and others. None of these products, however, have eliminated all of the above deficiencies. For example, while synthetic corks can be made to provide a steady and customizable amount of oxygen flow into a wine bottle, a synthetic cork with an oxygen transfer rate similar to that of cork would use a material so hard that excessive force would be needed to remove it from the wine bottle neck. Screw caps, on the other hand, let in too little oxygen into the bottle. 
     Thus, there remains a need in the art for a screw cap closure with oxygen permeability characteristics suitable for packaging wine. 
     SUMMARY OF THE INVENTION 
     According to one aspect of the present invention, a liner for a wine bottle cap is constructed such that a gas, such as oxygen, that diffuses through the liner moves along a path within the liner whose length is greater than the thickness of the liner. In this manner, oxygen from the atmospheric air can diffuse through a relatively thin liner at a slow rate before reaching the bottled wine. In one approach, the liner is comprised of alternating layers of material semi-permeable to oxygen and material impermeable to oxygen, the impermeable layers containing open areas through which oxygen can diffuse. As oxygen diffuses through the alternating layers, the path(s) along which the oxygen diffuses is determined by the locations of the open areas in the impermeable layers. In this approach, therefore, liners with varying rates of oxygen diffusion may be created by designing and selecting the geometries of the liner layers to create diffusion paths of varying lengths. 
     According to another aspect of the present invention, a liner for a wine bottle cap is constructed such that the thickness of the liner at the center of the liner is greater than the thickness of the liner at the periphery of the liner, the liner being made of material that is semi-permeable to the gas. In this manner, oxygen from the air can diffuse through the liner at a slow rate due to the thickness of the liner in the center, while the liner is still relatively thin along the periphery, where the liner serves as a contact surface between the wine bottle cap and the rim of the wine bottle. 
     According to another aspect of the present invention, a screw cap closure for a wine bottle is constructed to comprise a plurality of ventilation holes that are connected by one or more raceways. The ventilation holes allow atmospheric air to pass through the screw cap closure top to reach and eventually diffuse through a liner inside the screw cap closure the raceway allows even distribution of air to all parts of the liner even when the screw cap closure and the liner are not precisely aligned. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other aspects and features of the present invention will become apparent to those ordinarily skilled in the art upon review of the following description of specific embodiments of the invention in conjunction with the accompanying figures, wherein: 
         FIG. 1  illustrates a cross section of an exemplary assembled bottle cap and liner. 
         FIG. 2  illustrates a cross section of an exemplary multi-layer liner. 
         FIG. 3  illustrates a top view of the multiple layers of an exemplary multi-layer liner. 
         FIG. 4  illustrates sheets for constructing the multiple layers of an exemplary multi-layer liner. 
         FIG. 5  illustrates multiple layers of an exemplary multi-layer liner. 
         FIG. 6  illustrates multiple layers of an exemplary multi-layer liner. 
         FIG. 7  illustrates an exemplary liner that is thicker in the middle than in the periphery. 
         FIGS. 8A and 8B  illustrate an exemplary screw cap closure. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention will now be described in detail with reference to the drawings, which are provided as illustrative examples of the invention so as to enable those skilled in the art to practice the invention. Notably, the figures and examples below are not meant to limit the scope of the present invention to a single embodiment, but other embodiments are possible by way of interchange of some or all of the described or illustrated elements. Moreover, where certain elements of the present invention can be partially or fully implemented using known components, only those portions of such known components that are necessary for an understanding of the present invention will be described, and detailed descriptions of other portions of such known components will be omitted so as not to obscure the invention. In the present specification, an embodiment showing a singular component should not be considered limiting; rather, the invention is intended to encompass other embodiments including a plurality of the same component, and vice-versa, unless explicitly stated otherwise herein. Moreover, applicants do not intend for any term in the specification or claims to be ascribed an uncommon or special meaning unless explicitly set forth as such. Further, the present invention encompasses present and future known equivalents to the known components referred to herein by way of illustration. Still further, the drawings are provided for illustration and not limitation or exact reproduction of embodiments of the invention, and they are not necessarily to scale. 
     According to one approach, a liner for a wine bottle cap is constructed such that a gas such as oxygen, that diffuses through the liner moves along a path within the liner whose length is greater than the thickness of the liner. In this manner, a gas such as oxygen from the atmospheric air can diffuse through a relatively thin liner at a slow rate before reaching the bottled wine.  FIG. 1  depicts a cross section of an assembled wine bottle cap  102  and liner  104 . Liner  104  is located within the wine bottle cap  102  and is adjacent to the lower surface of the wine bottle cap&#39;s top  106 . Wine bottle cap  102  may be constructed from metal such as aluminum or steel that are impermeable to atmospheric air, and contains one or more openings, or ventilation holes, through which atmospheric air can pass to reach liner  104 . In one embodiment, wine bottle cap  102  is a screw cap closure. It should be noted, however, that other embodiments of the present invention may include liners that are fitted within bottle cap closures other than screw cap closures and bottle cap closures for bottles other than wine bottles. 
     According to one approach, a liner for a wine bottle cap, such as liner  104  in  FIG. 1 , comprises two or more layers that include at least one semi-permeable layer and at least one impermeable layer. Semi-permeable layers are constructed from materials that are semi-permeable to oxygen such that oxygen can diffuse through the semi-permeable layers. An example of a material that is semi-permeable to oxygen is polyethylene. Material for semi-permeable layers may also be slightly elastic so that the semi-permeable layers may be compressed in the areas where the liner is sandwiched between the rim of the bottle below and the screw cap closure above. This elasticity fills any irregularities in the sealing surface and ensures a tight seal for the bottle. 
     Materials impermeable to oxygen include aluminum foil and tin. The liner may further comprise layers that are permeable to oxygen, such as a food-grade polymer such as polyvinyl dichloride (e.g., Saran). These permeable materials allow small amounts of oxygen to diffuse through them whereas non permeable layers effectively allow no oxygen to permeate through. In one embodiment, the top and bottom layers of the liner comprise permeable layers that are constructed from food-grade material. In an alternative embodiment where the impermeable layers are constructed from food-grade material, the liner contains no top and bottom permeable layers. Although the descriptions here of semi-permeable and impermeable layers focus on whether the layers are permeable to oxygen, it will be appreciated that other embodiments of the present invention may employ liner layers that are semi-permeable or impermeable to other gases. 
     The liner may be constructed such that successive layers alternate between a permeable or semi-permeable layer and an impermeable layer.  FIG. 2  illustrates a cross section of an assembled liner  200  that includes five layers  202 ,  204 ,  206 ,  208 , and  210 . Layers  202  and  210  are permeable to oxygen, layer  206  is semi-permeable to oxygen, and layers  204  and  208  are impermeable to oxygen. As  FIG. 2  illustrates, liner  200  comprises successive layers that alternate between a permeable or semi-permeable layer (i.e., layers  202 ,  206 , and  208 ) and an impermeable layer (i.e., layers  204  and  208 ). According to one embodiment, the liner&#39;s impermeable layers comprise one or more apertures through which oxygen is allowed to pass through. For example, impermeable layer  204  in liner  200  contains apertures  212 , and impermeable layer  208  similarly contains apertures  214 . As a result, oxygen diffusing through a liner passes through the entire surface areas of the liner&#39;s permeable layers and semi-permeable layers and the apertures of the liner&#39;s impermeable layers. In the example illustrated in  FIG. 2 , oxygen that diffuses through liner  200  from top to bottom passes through the entirety of permeable layer  202 , the apertures  212  of impermeable layer  206 , the entirety of semi-permeable layer  206 , the apertures  214  of impermeable layer  208 , and finally, the entirety of permeable layer  210 . 
     Because oxygen cannot pass through the entire surface areas of impermeable layers and can only pass through the apertures of the impermeable layers, oxygen diffusing through a liner is forced to diffuse along paths, within permeable or semi-permeable layers sandwiched between two impermeable layers, that connect the apertures of the two impermeable layers. As a result, oxygen diffusing through the liner is forced to travel a longer distance, thereby achieving a slow oxygen diffusion rate even for relatively thin liners. Referring to the example illustrated in  FIG. 2 , oxygen diffusing through liner  200  from top to bottom diffuses through layers  204 ,  206 , and  208 , in that order. Semi-permeable layer  206  is sandwiched between impermeable layers  206  and  208 . Oxygen enters semi-permeable layer  206  through the apertures  212  in impermeable layer  204 . However, the oxygen in semi-permeable layer  206  can exit only through the apertures  214  in impermeable layer  208 . As a result, oxygen in semi-permeable layer  206  is forced to travel along a path that is at least as long as path length PL. 
     Generally, when the locations of apertures in the two sandwiching impermeable layers (e.g., layers  204  and  208 ) are different, oxygen diffusing through the sandwiched permeable or semi-permeable layer (e.g., layer  206 ) will be forced to travel some distance before being able to leave the sandwiched permeable or semi-permeable layer. When oxygen diffuses through a liner vertically (i.e., enters the liner from the top and exits the liner from the bottom), as is the case with liners encased in bottle caps such that the sides of the liners are adjacent to impermeable material such as metal, and oxygen enters from ventilation holes in the bottle cap near the top of the liner, there is horizontal diffusion of oxygen (e.g., for a distance of PL) in the permeable or semi-permeable layers that are sandwiched between two impermeable layers. 
     According to one approach, liner  200  is constructed such that path length PL is greater than the thickness of liner  200 . In another approach, path length PL may be smaller than the thickness of liner  200 , but liner  200  may additionally include more layers such that the total amount of distance traveled by oxygen diffusing through liner  200  is greater than the thickness of liner  200 . 
     According to one approach, the impermeable layers of a liner include a plurality of perforations, the location of the perforations being different between successive impermeable layers. For example,  FIG. 3  depicts a top view of the multiple layers of an assembled liner that includes five layers  302 ,  304 ,  306 ,  308 , and  310 . Layers  302 ,  304 ,  306 ,  308 , and  310  may correspond to layers  202 ,  204 ,  206 ,  208 , and  210  in  FIG. 2 . As depicted, the impermeable layers  304  and  308  each comprise a plurality of perforations  312  and  314 , respectively, which are differently located on layers  304  and  308 . Oxygen passing through the liner comprising the layers of  FIG. 3  is thus required to travel at least a distance of PL within semi-permeable layer  306 . 
     In one approach, the one or more impermeable layers of a liner are constructed from sheets of material that include a first strip area that contains a plurality of perforations and a second strip area that contains no perforations. For example,  FIG. 4  depicts a sheet  404  that contains two strip areas containing perforations and three strips areas containing no perforations. Sheet  404  may be composed of aluminum foil or tin. An impermeable layer for a liner can be constructed by cutting sheet  402  into circular areas, such as circular area  412  and circular area  414 .  FIG. 4  additionally depicts sheet  408 , which also has sheet areas containing perforations and sheet areas containing no perforations. As shown, sheet  408 &#39;s perforations are located differently from the perforations on sheet  404 . A same circular area, such as circular area  412 , that is cut from both sheet  404  and sheet  408  results in two impermeable layers whose perforations are located differently from each other. Sheet  404  and sheet  408 , when sandwiching a permeable or semi-permeable layer, force diffusing oxygen to travel some horizontal distance to traverse the layers, as described above. 
       FIG. 4  also depicts sheets  402 ,  406 , and  408 . Sheets  402  and  408  are sheets of permeable material and may be composed of a food-grade polymer, such as polyvinyl dichloride (e.g., Saran). Sheet  406  is a sheet of semi-permeable material and may be composed of polyethelene. As shown, sheets  402 ,  404 ,  406 ,  408 , and  410  may be stacked and circular areas may be cut from the stack of sheets to construct the multiple layers of a liner, such as layers  302 ,  304 ,  306 ,  308 , and  310  in  FIG. 3 . 
     According to one approach, the successive impermeable layers of a liner contain holes that are differently located. For example, a first impermeable layer may contain a single hole in the middle, and a second impermeable layer that is the next impermeable layer below may contain a number of holes (e.g., four holes) located along the periphery of the impermeable layer. A third impermeable layer that is the next impermeable layer below the second impermeable layer may contain a single hole in the middle again. Referring to  FIG. 5 , a liner is constructed from impermeable layer  502 , semi-permeable layer  504 , impermeable layer  506 , semi-permeable layer  508 , impermeable layer  510 , and permeable layer  512 . Impermeable layers  502 ,  506 , and  510  are successive impermeable layers that contain hole(s) that are different from the impermeable layers immediately above or below. For example, impermeable layer  502  contains a single hole, impermeable layer  506  contains four holes located on a ring-shaped path along layer  506 &#39;s periphery, and impermeable layer  510  also contains a single hole. In this geometry, oxygen diffusing from one impermeable layer to the next impermeable layer must travel at least a distance equal to the distance between a hole located in the middle of a layer (e.g., hole  514 ) to a hole located near the periphery of a layer (e.g., hole  516 ). 
     According to another approach, an impermeable layer sandwiched between two permeable or semi-permeable layers has a diameter that is smaller than the diameter of the liner, effectively resulting in the two permeable or semi-permeable layers contacting in an annular area through which oxygen may diffuse.  FIG. 6  illustrates an example of this geometry. In  FIG. 6 , a liner is constructed from impermeable layer  602 , semi-permeable layer  604 , impermeable layer  606 , semi-permeable layer  608 , impermeable layer  610 , and permeable layer  612 . Impermeable layers  602  and  610  each contains a hole in the middle. Impermeable layer  606 , however, has a diameter that is smaller than the diameters of semi-permeable layers  604  and  608 , resulting in an annular contact area between layers  604  and  608  through which oxygen can diffuse. In this geometry, oxygen diffusing from one impermeable layer to the next impermeable layer must travel at least a distance equal to the distance between a hole located in the middle of a layer (e.g., hole  614 ) to the annular contact area between two semi-permeable layers resulting from the smaller diameter of a sandwiched impermeable layer. 
     According to another embodiment of the present invention, a liner for a wine bottle cap is constructed such that the thickness of the liner at the center of the liner is greater than the thickness of the liner at the periphery of the liner, the liner being made of material that is semi-permeable to the gas. In this manner, oxygen from the air can diffuse through the liner at a slow rate due to the thickness of the liner in the center, while the liner is still relatively thin along the periphery, where the liner serves as a contact surface between the wine bottle cap and the rim of the wine bottle.  FIG. 7  illustrates an example liner  700  constructed such that the thickness of the liner  700  at the center of the liner is greater than the thickness of the liner  700  at the periphery. When liner  700  is assembled with a bottle cap that has a ventilation hole in the center, oxygen from atmospheric air diffuses through liner  700  along paths such as path  702  and path  704 . The lengths of paths  702  and  704  are significantly greater than the thickness of liner  700  at the periphery. As a result, oxygen is able to diffuse through liner  700  at a slow rate while liner  700  maintains a relatively small thickness at the periphery that allows the liner to serve as a good contact surface between a wine bottle cap and the rim of a wine bottle. 
     As the above examples illustrate, the arrangement and geometry of semi-permeable and impermeable layers provide a mechanism through which the rate at which atmospheric gases (e.g., oxygen) diffuse through the liner and interact with the bottle contents (e.g., wine) can be regulated. For example, the positioning of holes and perforations can be varied to shorten or lengthen the distance that a gas travels horizontally within the liner, thereby increasing or decreasing the gas transmission rate. In the example illustrated in  FIG. 4 , the strip areas containing perforations may also be made wider or narrower to control the gas transmission rate. The strip areas containing perforations may be made so wide that there is effectively no horizontal diffusion of gas within the liner. In this case, the rate-limiting factor is the amount of aligned surface area between two successive impermeable layers. 
     By controlling the arrangement and geometry of the layers in the liner, a specific and precise rate of oxygen diffusion can be obtained. This is advantageous because different oxygen diffusion rates are optimal for different wines. For example, white wines require less oxygen than red wines. A liner may therefore be designed to provide an optimal oxygen diffusion rate for any bottled wine product. 
     According to one approach, a screw cap closure for a bottle is constructed to comprise a plurality of ventilation holes that are connected by one or more raceways. The ventilation holes allow atmospheric air to pass through the screw cap closure top to reach and eventually diffuse through a liner inside the screw cap closure. The raceway allows even distribution of air to all parts of the liner even when the screw cap closure and the liner is not precisely aligned. In one embodiment, the screw cap closure is assembled with the multi-layer liner described above. 
       FIGS. 8A and 8B  illustrate an example of a screw cap closure comprising four ventilation holes that are connected by a raceway.  FIG. 8A  is a top-down view of the screw cap closure  800 . Screw cap closure  800  contains ventilation holes  802  and raceway  804 .  FIG. 8B  is a perspective illustration of screw cap closure  800 . Atmospheric air passes through ventilation holes  802 . Raceway  804  comprises an embossed channel such that atmospheric air that entered through ventilation holes  802  is distributed all along raceway  804 . When screw cap  800  is assembled with a liner underneath, atmospheric air that entered through ventilation holes  802  is distributed along raceway  804  and reaches all parts of the top of the liner. 
     In other embodiments of the invention, screw cap closures may be constructed to contain ventilation holes and raceway geometries different from that depicted in  FIGS. 8A  and SB. For example, a screw cap closure may contain any number of ventilation holes located on a ring-shaped path along the periphery of the top of the screw cap closure. 
     Although the present invention has been particularly described with reference to the preferred embodiments thereof, it should be readily apparent to those of ordinary skill in the art that changes and modifications in the form and details may be made without departing from the spirit and scope of the invention. It is intended that the appended claims encompass such changes and modifications.