Patent Publication Number: US-6902170-B2

Title: Means for venting gas pressure buildup from a package

Description:
CROSS REFERENCE TO RELATED PATENT APPLICATION 
     This is a division of application Ser. No. 09/501,542, filed on Feb. 9, 2000, which is now U.S. Pat. No. 6,715,772 B1. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to gaskets. More particularly, the present invention relates to a gasket that enables gas to be vented from a package, while preventing a liquid from leaking therefrom. The gasket is particularly suited for use in a spray or pump package. 
     2. Description of the Prior Art 
     Many liquid products are placed and held in a package that may take the form of a bottle or container. Often the package has a dispensing mechanism, such as a trigger spray or finger pump integrated into the package. 
     These systems may hold liquids that volatilize into a gas, which increases the pressure inside the package creating a positive pressure gas generating system. In a closed bottle or container, the positive pressure gas generating system can build up pressure that will ultimately distort the package. In fact, if the pressure is great enough, the package could burst and release the liquid held inside. To resolve this problem, gaskets have been made that permit excess gas to exit the package while preventing the liquid contained within from leaking out. These gaskets have a single gas permeable layer bonded to a core that prevents liquid from leaking out. DURAVENT gaskets manufactured and sold by W.L. Gore &amp; Associates, exemplify such gaskets. They are designed so that one side of the gasket allows gas to enter or escape a container along the threads of a cap. 
     However, in order for the gasket to function properly, the gasket must be positioned in the assembled piece so that the gas permeable layer is facing the liquid side. To properly place the gasket in the workpiece requires the use of an orientation device, i.e., human or mechanical means. This extra manufacturing step can significantly increase the manufacturing costs of the finished product. 
     BRIEF SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a gasket that is capable of venting gas from a package, such as a bottle or a container. 
     It is another object of the present invention to provide such a gasket that prevents liquid from leaking out of the package. 
     It is still another object of the present invention to provide such a gasket that is used in connection with a spray or pump dispenser. 
     It is still yet another object of the present invention to provide such a gasket that can be positioned in a closure fitting without using an orientation device. 
     It is a further object of the present invention to provide a method for venting gas from the package, while preventing liquid from leaking therefrom. 
     To accomplish the foregoing objects and advantages, the present invention, in brief summary, is a multi-layer gasket that is capable of venting gas from a bottle or a container while preventing liquid from leaking. The gasket is particularly suited for use in connection with a spray dispenser, such as a trigger spray, or pump dispenser, such as a finger pump. The gasket comprises a liquid impermeable core having a first side and a second side, and a first gas permeable outer layer connected to the first side and a second gas permeable outer layer connected to the second side opposite the first layer. More preferably, the core and two outer layers are laminated together. 
     The present invention also includes a method for relieving and preventing gas pressure buildup in a package, by utilizing a closure fitting having the gasket of the present invention that allows for passive venting of excess gas pressure from the package. The method comprises the step of securing a closure fitting having a gasket of the present invention about an opening of a package without the need for orientation of the gasket. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a gasket of the present invention; 
         FIG. 2  is a perspective view of a cross-section of the gasket of  FIG. 1 ; 
         FIG. 3  is a perspective view showing the gasket of  FIG. 1  in a trigger spray assembly; 
         FIG. 4  is a perspective view showing the gasket of  FIG. 1  in a finger pump assembly; and 
         FIG. 5  is a front view with portions cut away showing the flowpath of gas through the gasket of FIG.  1 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to the drawings and, in particular,  FIG. 1 , there is provided a gasket generally represented by reference numeral  10 . The gasket  10  is capable of venting gas from a package while preventing liquid from leaking therefrom. The package may be a bottle, a container, a cup or any other analogous object capable of holding a liquid. 
     The gasket  10  is multi-layered. Gasket  10  has a core  20  with a first outer layer  30  connected to a first side  22  of the core and a second outer layer or membrane  40  connected to a second side  24  of the core. In the  FIG. 1  embodiment, gasket  10  has two outer layers  30 ,  40  that are on opposite sides of core  20 , forming a tri-layer gasket. 
     The core  20  is made of a material that is impermeable to liquids and gases. Suitable materials include, but are not limited to, polyalkylene materials. Such polyalkylene materials include polyethylene, polypropylene, polybutylene, and mixtures thereof. Preferably, liquid impermeable core  20  is made of polyethylene. 
     Referring to  FIGS. 1 and 2 , outer layers  30  and  40  are each made of a gas permeable membrane material. The gas permeable membrane enables gas molecules to permeate through the membrane. 
     Preferably, gas permeable outer layers or membranes  30 ,  40  are each made of a fluoropolymer material. More preferably, the fluoropolymer material is an expanded polytetrafluoroethylene (ePTFE) polymer. One example of a commercially available expanded PTFE is a material from W.L. Gore under the tradename SUPER-RESISTANT GORE-TEX® MEMBRANE. 
     Moreover, outer layers  30 ,  40  are either bonded or laminated to first side  22  and second side  24  of core  20  so that outer layers  30 ,  40  and the core are a one piece, and perhaps integral, structure. 
     The thickness of core  20  is about 0.015 inches to about 0.150 inches and, preferably, about 0.020 inches to about 0.100 inches. The thickness of each outer layer  30  or  40  is about 0.001 inches to about 0.050 inches and, preferably, about 0.005 inches to about 0.030 inches. The actual thickness of outer layers  30 ,  40 , and thus gasket  10 , within the ranges set forth above will depend to a certain extent to the amount of pressure applied to secure the gasket to a package as will be discussed below. 
       FIG. 3  shows the position of gasket  10  in a trigger spray mechanism  100 .  FIG. 4  shows the position of gasket  10  in a finger pump mechanism  110 . In each mechanism or closure fitting, gasket  10  is positioned against an underside  220  of a cap closure  210 . 
       FIG. 5  is a schematic view that better shows the positioning of gasket  10  on a package, such as container or bottle  300 , having either mechanism  100 ,  110 . With either mechanism  100 ,  110  secured to bottle  300 , there is an amount of gas  400  and, preferably, liquid in the bottle. 
     The bottle  300  has a receiving portion that mates with a closure fitting, such as mechanisms  100 ,  110  shown in  FIGS. 3  and  4 , respectively. In  FIG. 5 , the receiving portion is necked down portion  310  preferably with threads  315 . The threads  315  are adapted to receive mating threads in the interior of either mechanism  100 ,  110 . The necked down portion  310  has an opening with a peripheral edge  320  and an exterior surface  330 . The above example demonstrates one embodiment. However, it should be understood that other embodiments are also contemplated including, but not limited to, snap fittings. 
     Referring to  FIG. 5 , outer layer  30  in the tri-layer gasket  10  shown in  FIG. 1  is positioned to contact peripheral edge  320 . Gas  400 , contained within bottle  300 , permeates through outer layer  30 , travels tangentially across gasket  10 , and then down along exterior surface  330 . However, liquid is prevented from passing by gasket  10 , since both core  20  and outer layer  30  are constructed of a liquid impermeable material. 
     Significantly, the tri-layer gasket  10  will invariably have the gas permeable outer layer facing the liquid surface so that it can be installed without concern for its orientation. 
     The diameter or radial size and the shape of gasket  10  will vary according to its application. These dimensions are largely determined by package design. For example, the diameter or radial size and shape of the opening of bottle  300  and the size and shape of the interior of mechanisms  100 ,  110  for receipt of gasket  10  will determine the size and shape of the gasket. Basically, gasket  10  needs to be sized and shaped to mate in liquid tight engagement with the contours of the interior of mechanisms  100  or  110 . These mechanisms  100 ,  110  in turn must mate in liquid tight engagement with the opening of bottle  300 . 
     As briefly stated above, the thickness of gasket  10  will vary depending upon certain application criteria. For example, outer layers  30 ,  40  should have an effective thickness to enable gas to permeate through it. The thickness will be dependent upon the downward forces or torque applied to secure mechanism  100 ,  110  in place on bottle  300 . Optimally, it is desired that the thickness of layers  30 ,  40  and, thus gasket  10 , be as thin as possible in order to reduce the amount of material. Therefore, the vertical space or height required in mechanisms  100 ,  110  should be only enough to receive gasket  10  and permit gas to permeate through the gasket. 
     The present invention also provides a method for venting gas from a positive pressure generating system in a package, such as a bottle or container. The method includes securing a closure fitting shaped to form a seal at an opening of a package having liquid therein. The closure fitting has gasket  10  that is capable of venting gases while preventing liquid from leaking therefrom. 
     The present invention also provides a method for sealing an opening in a package. The method comprises the step of securing a closure fitting shaped to form a seal at an opening of a package. 
     To illustrate the present invention, the following examples are provided. It should be understood that the present invention is not limited to the following: 
     A cleaning composition set forth below containing hydrogen peroxide was tested. When exposed to adverse conditions, such as elevated temperatures for a prolonged period of time, the hydrogen peroxide decomposes and generates oxygen gas. 
     
       
         
           
               
               
               
             
               
                   
                   
               
               
                   
                 Ingredient 
                 Weight % Active 
               
               
                   
                   
               
             
            
               
                   
                 Water 
                 Q.S. 
               
               
                   
                 Hydrogen Peroxide 
                 3.00 
               
               
                   
                 Cleaning Surfactants 
                 1.15 
               
               
                   
                 Organic Solvents 
                 2.00 
               
               
                   
                 Soil Resist Agents 
                 0.70 
               
               
                   
                 pH Control Agents 
                 0.40 
               
               
                   
                 Preservative 
                 0.10 
               
               
                   
                 Fragrance 
                 0.15 
               
               
                   
                   
               
            
           
         
       
     
     EXAMPLE 1 
     In Example 1, the tri-layer gasket was placed into twenty-five finger pump sprayers. The finger pump sprayers were then attached to the bottles. A control finger pump sprayer bottle, that did not contain the gasket of the present invention, was also tested. High density polyethylene (HDPE) bottles were filled with 8.5 oz. of the above cleaning composition. The finger pump sprayer was hand torqued onto each bottle. Fifteen of the twenty-five bottles having the gasket were placed in an upright vertical position and maintained in that position for the duration of the test. Ten of the twenty-five bottles were initially placed in an inverted position for one week, then the samples were placed in the upright position. In the latter, the gasket was thus directly exposed to the cleaning composition. In the inverted position, the gasket would not vent. The ten bottles started to swell. If not repositioned to an upright position, the ten bottles would eventually rupture. All samples were placed in a 123° F. temperature controlled chamber. Periodically, the samples were removed from the chamber to measure the width and depth of each bottle. The fifteen bottles in the upright position that had the gasket of the present invention remained relatively unchanged. The control bottle, that did not contain the gasket, experienced a reduction in width and an increase in depth. Results after ten weeks are shown in the following table. 
     
       
         
           
               
               
               
               
            
               
                   
                   
               
               
                   
                   
                 Average of 10 
                   
               
               
                   
                 Average of 15 
                 Inverted 
                 Single 
               
               
                   
                 Right Side Up 
                 Right Side Up 
                 Control Bottle 
               
            
           
           
               
               
               
               
               
               
               
            
               
                 Week 
                 Width 
                 Depth 
                 Width 
                 Depth 
                 Width 
                 Depth 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 Initial 
                 69.9 
                 40.8 
                 70.0 
                 40.8 
                 69.0 
                 42.7 
               
               
                 1 
                 69.7 
                 41.2 
                 65.9 
                 46.3 
                 63.7 
                 49.5 
               
               
                 2 
                 69.5 
                 41.4 
                 67.7 
                 43.7 
                 62.4 
                 50.9 
               
               
                 3 
                 69.5 
                 41.4 
                 68.1 
                 43.2 
                 61.7 
                 51.7 
               
               
                 4 
                 69.6 
                 41.5 
                 68.1 
                 43.3 
                 61.8 
                 51.8 
               
               
                 5 
                 69.5 
                 41.3 
                 68.9 
                 42.2 
                 60.3 
                 53.0 
               
               
                 6 
                 69.5 
                 41.5 
                 69.0 
                 42.1 
                 * 
                 * 
               
               
                 7 
                 69.4 
                 41.5 
                 68.8 
                 42.2 
               
               
                 8 
                 69.5 
                 41.3 
                 68.9 
                 42.0 
               
               
                 9 
                 69.5 
                 41.3 
                 69.0 
                 42.1 
               
               
                 10 
                 69.6 
                 41.0 
                 69.0 
                 42.0 
               
               
                   
               
               
                 * Bottle developed leak  
               
               
                 ** Widths and depths were measured in millimeters using a hand held caliper  
               
            
           
         
       
     
     The results demonstrate that in the upright position, bottles having the pump sprayer equipped with the gasket of the present invention did not deform. They maintained their shape while venting gas pressure build up. Bottles that were first inverted, then repositioned right side up, did not vent at first. While inverted, the bottles started to swell as expected, but did not leak. When the bottles were repositioned, the bottles did vent and started to resume their original shape. The control bottle, which does not have the gasket, swelled to a point where the bottle ultimately split at the seams and the contents of the bottle leaked out. 
     EXAMPLE 2 
     A removal torque study was performed comparing a tri-layer gasket bottle against a bi-layer gasket bottle. Four bi-layer and four tri-layer gasket bottles were tested at each application torque level. Sample bottles were each filled with 252 grams of water. Tri-layer and bi-layer gaskets were inserted by hand into finger pump sprayer bottles. The pumps were then placed onto the bottles and hand torqued at 10 inch-lbs., 12 inch-lbs., 15 inch-lbs., and 18 inch-lbs. The sample bottles were left undisturbed for a minimum of forty minutes before removing the pump sprayers and measuring the removal torque required to do so. 
     
       
         
           
               
            
               
                   
               
               
                 Average Removal Torque Observed (inch-lbs.) 
               
            
           
           
               
               
               
               
               
            
               
                   
                 10 
                 12 
                 15 
                 18 
               
               
                   
                 inch-lbs. 
                 inch-lbs. 
                 inch-lbs. 
                 inch-lbs. 
               
               
                   
                   
               
            
           
           
               
               
               
               
               
            
               
                 Bi-layer 
                 5.4 
                 7.3 
                 7.5 
                 8.8 
               
               
                 Tri-layer 
                 5.9 
                 7.5 
                 8.3 
                 9.3 
               
               
                   
               
            
           
         
       
     
     The above results indicate that sprayer pumps utilizing the tri-layer gasket for venting purposes display a higher removal torque, on average, than the corresponding bi-layer gasket. What this means is that the tri-layer gasket creates a tighter seal, which is shown as its higher resistance to back torquing. Thus, the tri-layer gasket resists loosening of the pump closure on the bottle to a greater degree than the bi-layer gasket. 
     Having thus described the present invention with particular reference to preferred embodiments thereof, it will be apparent that various changes and modifications may be made therein without departing from the spirit and scope of the invention as defined in the appended claims.