Abstract:
A method of applying a liner to a container mouth in a hot-fill operation, said method comprising the steps of: placing the liner over a mouth sealing surface of the container; heating the liner by induction or conduction; and cooling the liner immediately thereafter while biasing the liner against the mouth sealing surface for a sufficient length of time to permit curing and sealing of the liner to the mouth sealing surface.

Description:
FIELD OF THE INVENTION 
       [0001]    The invention relates to an inner seal for a container and more particularly to a pull-tab for the inner seal to permit a proper seal while allowing for easy removal of the inner seal to the container. 
       BACKGROUND OF THE INVENTION 
       [0002]    A heat sealable inner seal is often used in sealing a container for products such as anti-freeze, peanut butter, mayonnaise, liquid detergent, etc. Such an inner seal prevents leakage and is also popular for providing an indication of whether there has been tampering with the contents of a container. 
         [0003]    Presently, a heat sealable inner seal generally includes a multi layer composite structure with an upper layer of metallic foil which is attached to a lower layer of adhesive material which bonds the heat seal material. The inner seal also can include an upper backing layer. Generally, the inner seals are inserted into caps and shipped to a packager of containers. The packager places the caps onto filled containers, with the coating of heat sealable material being in contact with the land area of the neck of the containers. The containers then pass through a conduction heating system which conducts heat into the foil, under an induction heater which generates heat within the metallic foil causing the temperature of the foil to increase. The high temperature of the foil melts the attached heat sealable adhesive layer, causing the inner seal to bond to the container. 
         [0004]    In a hot fill process and after the product is filled in the container, the liner, when placed on the container, may have an edge curl up, thus will not seal properly. The bonding between the heat sealable layer and container may be weak or may not occur and prevent the inner seal from performing its sealing function. As a result, the predominant closures for hot-fill have been metal or closures with imbedded liners. Therefore, it is desirable to maintain the liner in contact with the mouth of the container and to heat the foil to a temperature within a desired temperature range to ensure proper bonding of the inner seal to the container. 
       SUMMARY OF THE INVENTION 
       [0005]    In hot-fill food packaging, with bottles, the use of liners is increasing. The process generally involves filling product into the bottle or other container, placing the liner on the mouth of the bottle or other containers, and heat sealing through induction or conduction. The subject invention involves immediately cooling the liner while holding it against the bottle mouth sealing the surface. The cooling may be accomplished by sprayed water or other application of water, a refrigerated plate or simply blowing refrigerated air at the liner. The liner may be secured against the mouth of the bottle by the refrigerated plate. A conveyor may also be used to apply pressure to the liner while it is on the mouth of the bottle. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0006]    The present invention will be more readily apparent from the following detailed description of the invention and the appended claims, when taken in conjunction with the accompanying drawings in which: 
           [0007]      FIG. 1  is an exploded perspective view of a closure package and an associated container, the closure package including a liner having a pull-tab embodying the principles of the present invention; 
           [0008]      FIG. 2  is a partial cross-sectional view of an exemplary laminate structure of the liner material; 
           [0009]      FIG. 3  is a top plan view of a liner with pull-tab; 
           [0010]      FIG. 4  is a side view of an apparatus for utilizing the subject inventive method; and 
           [0011]      FIG. 5  is a side view of an alternate apparatus for utilizing the subject inventive method. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0012]    While the present invention is susceptible of embodiment in various forms, there is shown in the drawings and will hereinafter be described a presently preferred embodiment with the understanding that the present disclosure is to be considered an exemplification of the invention and is not intended to limit the invention to the specific embodiment illustrated. 
         [0013]    Referring now to the figures and particularly to  FIG. 1 , there is shown a closure package  10  including a closure cap  12  and a liner  14  showing a typical container cap and liner. The package  10  is for use with an associated container  16 . The exemplary container  16  has a threaded neck portion  18  having a finish  20 . The finish  20  is that portion of the container  16  including the upper region which engages the cap  12 , e.g., the threaded area  18  and an uppermost sealing surface  22  of the container  16 . The container threads  18  engage complementary threads (not shown) formed on an inner surface of the cap  12 . It will be recognized by those skilled in the art that the closure package  10  described herein can be used with containers having a snap-like or beaded engagement configuration. 
         [0014]    The cap  12  has a top wall portion  30  and a depending skirt portion  32  depending from the top wall portion  30 . The inner surface  34  of the top wall portion  30  is adapted to coact with the sealing surface  22  of the container  16  to form a seal therebetween. When the package  10  is assembled, the liner  14  comprises a circular disc and resides between the top wall portion  30  of the cap  12  and the sealing surface  22  of the container  16 , spanning the opening or mouth  36  of the container  16 . 
         [0015]    The liner  14  has a central portion  40  that is positioned over and in use, sealed to the sealing surface  22  of the container  16 . As shown in  FIG. 3 , a tab  42  may be integral with the central portion  40 , and extends from a periphery  44  thereof. The tab  42  defines a grasping portion  46 , that, when folded, is adapted to facilitate removing the liner  14  from the container  16 . 
         [0016]    In one embodiment, as illustrated in  FIG. 2 , the liner  14  is formed from a laminate material M having a resilient substrate layer  50 , a foil or like gas-impermeable layer  52 , and a heat activated bonding layer  54 , such as a heat activated adhesive. In a current embodiment, the resilient substrate layer  50  is a closed cell foam material, but can be chip board or paper backed and/or coated and is relatively impervious to the environs and establishes an air-tight seal between the container  16  contents and the environs. The resilient material layer  50  permits the cap  12  to be closely fitted to, and tightened onto, the container  16 . 
         [0017]    Attention is now directed to  FIG. 4 . where a linear-conveyor embodiment of a sealing apparatus, generally designated  70 , is illustrated for sealing a heat-sealable liner  14  to a container  20  having an open end  36  ( FIG. 1 ) upon which liner  40  is to be fused. Sealing apparatus  70  includes an elongated frame  73 , and a first surface  76  for support and moving the container/liner combination along a pathway. A second conveyor assembly, generally designated  77 , is coupled to frame  73  and extends along and is adjacent and directly above first surface  76 . Second conveyor assembly  77  includes a relatively rigid second surface  90  in opposed moving relation to the first surface  76  for further transport of the container/liner combination between the first and second conveyor assemblies along the pathway. A cooling element  92  may be positioned longitudinally and parallel to a portion of one of first surface  76  and second surface  90 . The cooler directs refrigerated air against conductive plates  94  on second conveyor assembly  77 . The conductive plates  94  are cooled by the cooling element  92  and travel along the conveyor belt path for contact with the container closure so that the heat of the hot-fill process is absorbed by refrigerated surfaces of the conductive plates  94 . The conductive plates  94  then travel further along the pathway to be cooled by the cooler  92  again. 
         [0018]    The containers may be cooled by spraying the bottles with a refrigerant or other fluid, such as water, to cool the containers while pressure is being applied to the liner. This is shown in  FIG. 5  with water spray line  95 . If desired, the liner may be cooled by the sprayed media also. Further, a blower  93 , as shown in  FIG. 5 , may be used to blow refrigerated air against the containers to cool down the containers and their contents after a hot fill. The cooling media may also be directed against the liner. 
         [0019]    Thus, the liner is cooled after the hot-fill process. Further, the second conveyor assembly  77  biases the second surface  90  thereof toward the first surface  76  against the containers  15  on the first conveyor to provide a substantially constant pressure between sealing surface  22  and liner  40  as the two travel on the conveyor as a unit. 
         [0020]    As each container/liner combination  15  passes between the opposing first and second conveyor assemblies  76  and  77 , respectively, they cooperate to squeeze liner  40  against container mouth or sealing surface  22  at a constant pressure during passage through the pathway. A constant pressure is thus applied between the container mouth sealing surface  22  and the liner  40  which squeezes and maintains pressure during the cooling process of the liner  40 , to thereby keep the liner in a sealed condition after the fusing of the liner in the induction process. 
         [0021]    While the container/liner assembly travels along first conveyor assembly, a blast of refrigerated media such as air or liquid from refrigeration blower  93  may be directed to the liner surface as graphically depicted in  FIG. 5  for a duration and at a temperature sufficient to cool the liner immediately after the induction or conduction heating and ensure curing and sealing of the liner upon the container mouth. 
         [0022]    It will be understood that the foregoing description is of preferred exemplary embodiments of the invention and that the invention is not limited to the specific forms shown or described herein. Various modifications may be made in the design, arrangement, and type of elements disclosed herein, as well as the steps of making and using the invention without departing from the scope of the invention as expressed in the appended claims.