Abstract:
The present invention provides a bottle cap for use in association with a bottle. The cap has a roof and sidewall, and is releasably attachable to the bottle. A flexible membrane is attached to the cap whereby an air tight seal between the flexible membrane and the bottle rim is achievable when the cap is attached to bottle. The flexible membrane is moveable responsive to change in pressure inside the bottle and the flexible membrane has an inside between the membrane and the cap. The cap has at least one flow means between the outside of the cap and the inside of the flexible membrane whereby air can move freely between the outside of the cap and the inside of the flexible membrane. The flexible membrane remains attached to the cap when the cap is removed from the bottle.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates to caps for plastic bottles and jars and in particular to caps that equalize pressure in the plastic bottle during cooling. The pressure equalizing cap of the present invention is particularly useful after a plastic bottle or jar has been hot filled or pressurized during filing by artificial means or by air pressure variations due to altitude changes. 
       BACKGROUND OF THE INVENTION 
       [0002]    Plastic bottles are in many instances the preferred bottle for most applications. However, to date products and fluids that are hot filled will more typically be sold in glass bottles, composite cans, metal cans or foil and paper semi-rigid containers. Many bottlers would prefer to use plastic bottles since they are easy to use, easy to manufacture, recyclable, less expensive and generally easier to transport and do not break. But, when plastic bottles are hot filled the plastic bottle will often distort during cooling. In order to reduce this problem, many plastic bottles have panels or stiffeners formed therein. Although these panels help the distortion problem, they pose problems for the bottler since it is more difficult to adhere a label to a bottle with panelling than a smooth surfaced bottle. Generally, distortion of most types of plastic packaging occurs when the plastic container is filled at temperatures above 185 0  F. 
         [0003]    A further drawback of plastic packaging occurs when a plastic-based product package is filled with hot fluid and then capped immediately and left to cool. A partial vacuum forms in the head-space in the container between the upper level of the food and the bottle cap with the consequent pressure differential between the interior of the bottle and the exterior resulting in distortion of the plastic container. This effect is commonly referred to as panelling which is characterized by noticeable and unsightly distortion of the shape of the bottle. In order to balance or eliminate the distortion of the bottle shape created by this partial vacuum it is a common practice to re-engineer the container to have a shape that can naturally counter the distortion induced in the container by cooling. In addition to re-engineering the shape of the container, it is also common practice to add significant gram weight to the container for the purpose of strengthening the walls and therefore resist the contractive forces created by the cooling of the container. Both these solutions add significant cost to the plastic container development costs. 
         [0004]    There are a number of prior art devices that are attached to the rim of a bottle and which may be sucked into the bottle when there is a pressure reduction in the bottle. Some examples of these prior art devices are shown in U.S. Pat. No. 756,234 issued to Heath Apr. 5, 1904, U.S. Pat. No. 3,833,142 issued to Owen et al Sep. 3, 1974 and U.S. Pat. No. 4,174,784 issued to Hartung Nov. 20, 1979. The Heath patent is an old patent directed to caps for milk bottles. The cap is a cardboard cap with a central hole formed therein and a thin sheet covers the hole. While a closure such as this provides some advantages when used with a milk bottle it could not be used with a plastic bottle with a threaded closure. The Owen device shows sealing a thin film of a stretchable plastic over the mouth of a plastic container. A breathable liner is placed over the stretchable plastic and then a cap is attached to the bottle. Hartung is similar to Owen in that it includes a membrane that is attached to the mouth of a bottle. Hartung includes a cap that has a vent hole formed in the top thereof. Although these devices show ways of equalizing pressure in a plastic bottle, none of them are attaching the flexible membrane to the cap rather they attached the flexible membrane to the bottle. Accordingly, when the user opens the bottle they will be presented with a bottle opening covered with a flexible membrane that they then have to pierce or remove in some way. Many consumers would find this unappealing. Further, these prior art caps have a vent hole in the cap which poses tamper problems. 
         [0005]    There is therefore a need for an economical and efficient means of adapting presently available standard plastic containers as packaging for foodstuffs that must be hot filled. Specifically it would be advantageous to provide a pressure equalization device that is removed when the bottle cap is removed. 
       SUMMARY OF THE INVENTION 
       [0006]    The present invention provides a bottle cap for use in association with a bottle. The cap has a roof and sidewall, and is releasably attachable to the bottle. A flexible membrane is attached to the cap whereby an air tight seal between the flexible membrane and the bottle rim is achievable when the cap is attached to the bottle. The flexible membrane is moveable responsive to change in pressure inside the bottle and the flexible membrane has an inside between the membrane and the cap. The cap has at least one flow means between the outside of the cap and the inside of the flexible membrane whereby air can move freely between the outside of the cap and the inside of the flexible membrane. 
         [0007]    In another aspect, the invention provides a bottle and cap assembly which comprises a pressure equalizing cap and a bottle having a generally smooth portion and a neck portion. The generally smooth cylindrical portion is free of panelling sections and the generally smooth portion is designed to have a label adhered thereto. 
         [0008]    Further features of the invention will be described or will become apparent in the course of the following detailed description. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    The invention will now be described by way of example only, with reference to the accompanying drawings, in which: 
           [0010]      FIG. 1  is a blown apart perspective view of the cap of the present invention in association with a bottle; 
           [0011]      FIG. 1   a  is a perspective view similar to that shown in  FIG. 1  but showing the cap assembled and removed from the bottle; 
           [0012]      FIG. 2  is a cross sectional view of the cap of the present invention screwed onto a bottle; 
           [0013]      FIG. 3  is a blown apart perspective view of an alternate cap constructed in accordance with the present invention; 
           [0014]      FIG. 4  is a cross sectional blown apart view of the cap of  FIG. 3 ; 
           [0015]      FIG. 5  is a cross sectional view of the cap of  FIG. 3  screwed onto a bottle; 
           [0016]      FIG. 6  is a cross section view of another alternate cap constructed in accordance with the present invention, wherein the cap has an upper cavity; 
           [0017]      FIG. 7  is a cross sectional blown apart view of the cap of  FIG. 6  screwed onto a bottle; 
           [0018]      FIG. 8  is a cross sectional view of the further alternate cap constructed in accordance with the present invention, wherein the cap has an inner portion, an outer portion and an upper cavity; and 
           [0019]      FIG. 9  is a blown apart perspective view of another alternate cap constructed in accordance with the present invention similar to that shown in  FIG. 3  and further including an outer sealing ring; 
           [0020]      FIG. 10  is a blown apart cross sectional view of the embodiment shown in  FIG. 9 ; 
           [0021]      FIG. 11  is a blown apart perspective view of another alternate cap constructed in accordance with the present invention including multiple bubbles; 
           [0022]      FIG. 12  is a cross sectional view of the cap of  FIG. 11 ; 
           [0023]      FIG. 13  is a cross section view of another alternate view of a cap constructed in accordance with the present invention similar to that shown in  FIGS. 11 and 12  but showing more bubbles; 
           [0024]      FIG. 14  is a cross sectional view of another alternate view of a cap constructed in accordance with the present invention similar to that shown in  FIGS. 11 and 12  but with an upper cavity; and 
           [0025]      FIG. 15  is a cross sectional view of another alternate view of a cap constructed in accordance with the present invention similar to that shown in  FIG. 14  but with an upper cavity. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0026]    Referring to  FIGS. 1 and 2 , the present invention is directed to a cap  10  that is adapted to be attached to a bottle  12 . The cap  10  of the present invention allows for pressure equalization as the bottle  12  cools. 
         [0027]    Preferably cap  10  includes an outer cap  14 , an inner cap  16  and a membrane  18 . The inner cap  16  is nested in the outer cap  14 . A flexible membrane  18  is positioned in the inner cap  16 . Inner cap  16  has an aperture  20  formed therein. There is an air space  22  between outer cap  14  and inner cap  16 . The flexible membrane  18  is moveable responsive to changes in pressure. Preferably, the flexible membrane  18  is made from food grade plastic. The flexible membrane  18  is preformed in a bubble shape. When the pressure is equal on both sides of the flexible membrane  18 ; it is flaccid. Alternatively it there is a differential in pressure between one side of the flexible membrane  18  then it will be pulled toward the bubble shape. The flexible membrane is made of material that has gas barrier characteristics. For example the flexible membrane may be made of EVOH (ethyl vinyl alcohol), PVA (polyvinyl alcohol), PVDC (polyvinyl dichloride), or some other chemistry to make the membrane more impervious to gas ingress Preferably the flexible membrane  18  has an outer rim  19  that is attached to the inside of the inner cap  16 . A sealing ring  21  may be used to seal the flexible membrane  18  to the inner cap  16 . It will be appreciated by those skilled in the art that there may be alternate ways of adhering the flexible membrane  18  to the inner cap  16 . 
         [0028]    The bottle  12  has a generally smooth portion  24 . Preferably the bottle is cylindrical but if desired it could also be generally square in cross section. The generally smooth portion makes it easy for the bottlers to adhere a label  26  thereto. The generally smooth portion  24  extends upwardly into a neck  28 . Preferably the bottle  12  includes a bottle threaded closure  30 . Similarly the cap  10  includes a cap threaded closure  32  formed on the inside of the inner cap  16  and which is adapted to engage the bottle threaded closure  30 . The flexible membrane  18  has an inside  21  between the membrane and the cap. 
         [0029]    The cap  10  and bottle  12  of the present invention are particularly useful in the hot fill of plastic bottles. The cap  10  of the present invention allows the pressure to equalize in the bottle  12  as the product therein cools. By providing a cap  10  that allows for the equalization of pressure in the bottle during cooling it reduces and in some cases eliminates the need for engineered panels on the bottle. Thus the cap of the present invention allows for the use of a bottle with a generally smooth portion  24 . This generally smooth portion makes it considerably easier to adhere a label  26  to the bottle than bottles that have engineered panels on the sides thereof. Current bottles that are hot filled are typically made of heat set PET which requires engineered panels and a substantial increase in the gram weight of the container. It will be appreciated by those skilled in the art that if the engineered panels are not required the gram weight of the bottle can be reduced by approximately 25%. Accordingly, the bottle of the present invention provides both a cost saving and an environmental saving. 
         [0030]    In use the bottle  12  is filled and then the cap  10  is attached to the bottle  12 . The cap  10  is attached such that there is initially an air-tight seal between the membrane  18  and the rim  34  of the bottle  12 . The flexible membrane  18  is initially in a flaccid state as shown at  23  in phantom in  FIG. 2 . As the heated product cools a vacuum is created inside the bottle and the flexible membrane  18  is sucked into the bottle. It will be appreciated by those skilled in the art that it is only when the cap is first attached to the bottle that it is important to achieve an air-tight seal between the flexible membrane  18  and the rim of the bottle. Thereafter once the cap has been opened the quality of the seal is less important. 
         [0031]    Once the cap is removed from the bottle since the flexible membrane  18  is attached to the cap it is removed with the cap as shown in  FIG. 1   a , It will be appreciated by those skilled in the art that this is a clear advantage over the prior art that has a seal attached to the rim of the bottle. Such a prior art seal can often be very difficult to remove. As well, these prior art seals are relatively unsightly and by moving the seal into the cap this consumer unfriendly appearance is reduced. Since the flexible membrane is attached to the cap rather than the bottle it is further distanced from the contents of the bottle thereby reducing the likelihood of the membrane coming in direct contact with the contents. 
         [0032]    Referring to  FIGS. 3 ,  4  and  5 , an alternate cap constructed in accordance with the present invention is shown generally at  40 . Cap  40  has a plurality of grooves  42  that extend through the threaded closure  44  and along the roof of the cap  40 . The cap  40  also includes a flexible membrane  46  and a sealing ring  48 . The sealing ring  48  helps to secure the flexible membrane  46  to the cap  40 . As can best be seen in  FIG. 5 , the grooves  42  are arranged such that when the cap is secured on the bottle  12  the grooves  42  provide a means for air to enter the inside  50  of flexible membrane. Thus as described above when a bottle is filled with hot product and the product cools the flexible membrane can be sucked into the bottle  12  and air is then sucking into the inside  50  of the membrane  46 . As described above when the bottle  12  is initially sealed there is an airtight seal between the flexible membrane  46  and rim  34  of the bottle  12  through the sealing ring  48 . 
         [0033]    Another alternate embodiment is shown in  FIGS. 6 and 7 . Cap  60  is similar to that shown in  FIGS. 3 ,  4  and  5  but having a cap upper extension  62 . This upper extension is particularly useful in the event that the bottles are filled at a higher altitude and as the bottle is brought to a lower altitude the flexible membrane  46  will tend to be sucked into the upper extension  62 . The remainder of the cap  60  is as described with regard to cap  40 . Specifically there are a plurality of grooves  42  that extend through threaded closure  44 . The flexible member  46  is held in place with a sealing ring  48 . It will be appreciated by those skilled in the art that the flexible membrane  46  may be sucked into the bottle  12  or sucked into the upper extension  62  as the pressure in the bottle  12  changes. 
         [0034]    Another alternate embodiment is shown in  FIG. 8 . Essentially cap  70  is a mixture of the features of cap  10  and cap  60 . Specifically cap  70  has an inner cap  72  nested inside of outer cap  74 . Outer cap  74  has an upper extension  76 . Inner cap has a central opening  78  so that flexible membrane  18  can be sucked into the upper extension  76 . As described above inner cap  72  and outer cap  74  allow air to flow therebetween such that air can be sucked into the inside  21  of the membrane  18 . 
         [0035]    Referring to  FIGS. 9 and 10 , an alternate cap is shown generally at  80 . Cap  80  is similar to cap  40  shown in  FIGS. 3 and 4 . In cap  80  sealing ring  82  is an inner sealing ring and cap  80  further includes an outer sealing ring  84 . The remainder of cap  80  is as shown in  FIGS. 3 and 4  with regard to cap  40 . Outer sealing ring  84  helps to stiffen the flexible membrane  46  during manufacture and use. 
         [0036]    Referring to  FIGS. 11 and 12 , an alternate embodiment of the cap of the present invention is shown generally at  90 . Cap  90  is similar to the caps shown previously but the flexible membrane  92  is preformed into a plurality of bubbles  94 . A sealing disc  96  has a plurality of apertures  98  formed therein. When assembled each aperture  98  is in registration with a bubble  94 . A plurality of grooves  100  are arranged such that each extends through the centre of the cap  90 . Flexible membrane  92 , sealing disc  96  and cap  90  are arranged such that when assembled each bubble  94  is in registration with an aperture  98  and at least one groove  100 . An alternative to cap  90  is shown in  FIG. 13  at  102  wherein cap  102  includes a plurality of bubbles  104 . Bubbles  104  are smaller than bubbles  94  such that for the same diameter of caps there will be more bubbles  104  than bubbles  94 . Caps  106 ,  108  shown in  FIGS. 14  and  15  are similar to those shown in  FIGS. 12 and 13  respectively but further including an upper cavity  110 ,  112 . In all other aspects caps  106  and  108  are the same as cap  90  and  102 . 
         [0037]    Caps having a membrane with a plurality of bubbles are particularly adapted for use with wide mouth jars. If a single bubble was used with a wide mouth jar there would be a risk that the bubble could be seen below the cap by a consumer which would be undesirable. As well, there is the risk that the bubble might be sucked into the food product which also would be undesirable. 
         [0038]    As used herein, the terms “comprises” and “comprising” are to construed as being inclusive and opened rather than exclusive. Specifically, when used in this specification including the claims, the terms “comprises” and “comprising” and variations thereof mean that the specified features, steps or components are included. The terms are not to be interpreted to exclude the presence of other features, steps or components. 
         [0039]    It will be appreciated that the above description related to the invention by way of example only. Many variations on the invention will be obvious to those skilled in the art and such obvious variations are within the scope of the invention as described herein whether or not expressly described.