Patent Publication Number: US-6221484-B1

Title: Venting tape

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to venting tape, and in particular to venting tape used to vent an enclosed article space to be filled with an expandable foam material. 
     Injected expandable foam materials are used to insulate numerous articles in a wide variety of applications, such as refrigerators, freezers, and the like. The expandable foam material is typically injected into the walls of the appliances between an outer housing and an inner casing, thereby providing a uniform thermal barrier therebetween. 
     The outer housing of these appliances are typically provided with holes and apertures for venting purposes during the injection of the foam material. These “vent holes” allow the manufacturer to provide an air-tight seal between the outer housing and the inner casing, while allowing air/gas to escape as the expandable foam fills the void therebetween. These holes must be temporary covered during the foam injection process to prevent the foam from escaping from between the inner casing and the outer housing. Heretofore, manufacturers have used foam pads to plug the holes. The pads are designed to allow gas to escape as the foam expands yet restricting the flow of foam through the holes. These pads must be specially cut and formed for each application thereby significantly adding to the cost of manufacture. Further, these pads are often difficult to install during the manufacturing process. In addition, the foam pads typically are supplied in the form of a large coil that is cumbersome to handle and control. Porous tapes have also been used to plug the holes. Several problems have been associated with these tapes including inadequate strength resulting in foam leakage, as well as inadequate air/gas flow resulting in non uniform fill of the injected foam within the appliance. In addition, porous tapes often tear when the expandable foam actually contacts the tape, thereby allowing the foam to escape from within the appliance. Improper venting is often caused by the adhesives associated with the tapes plugging the holes therein and disrupting the air flow therethrough. 
     SUMMARY OF THE INVENTION 
     One aspect of the present invention is to provide a venting tape for use in venting an article space to be filled with an injected expandable foam material, wherein the venting tape includes a polymeric film having a plurality of minute perforations formed therethrough. The perforations are sized to allow the passage of a gas therethrough yet prevent passage of expandable foam insulation. The venting tape further includes an adhesive layer on one side of the film in a pattern enabling a substantial portion of the minute perforations to remain uncovered by the adhesive layer. 
     Another aspect of the present invention is to provide a method for plugging the escape holes of an article space to be filled with an expandable foam material, the method including providing a polymeric film, and forming a plurality of perforations therethrough, wherein the perforations are sized to allow the passage of a gas therethrough yet prevent passage of expandable foam insulation. The method further including applying an adhesive layer to one side of the film in a pattern, and adhering the film over the escape holes of the article. 
     The principle objects of the present invention are to provide a relatively simple, cost effective way to adequately cover the vent holes of an appliance by allowing the gas/air to escape while retaining the expandable foam insulation with the appliance. The present inventive venting tape is easier to apply than the foam pads currently in use. Further, the present inventive venting tape has a relatively increased strength that allows the tape to resist tearing and withstand the increased pressure created when the expandable foam contacts the tape. In addition, by applying the adhesive to the film in a pattern, the adhesive does not plug all the perforations, thereby allowing expandable foam to effectively fill the void between the outer housing and inner casing. 
     These and other advantages and objects of the present invention will be further understood and appreciated by those skilled in the art by reference to the following specification, claims, and appended drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an enlarged, fragmentary, cross sectional side view of a vent tape embodying the present invention; 
     FIG. 2 is a perspective view of a roll of the vent tape; 
     FIG. 3 is a top view of a pre-cut section of the vent tape; and 
     FIG. 4 is a perspective view of a refrigerator. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENT 
     The reference numeral  10  (FIG. 1) generally designates a venting tape for use in venting an enclosed article space or void  38  (FIG. 4) to be filled with an injected expandable foam material  36 . Venting tape  10  includes a polymeric film  12  having a plurality of minute perforations  14  formed therethrough. Perforations  14  are sized to allow the passage of a gas or air therethrough yet prevent passage of expandable foam insulation  32  (FIG.  4 ). Venting tape  10  further includes an adhesive layer  16  on one side of film  12  that is applied in a pattern enabling a substantial portion of the perforations  14  to remain uncovered by adhesive layer  16 . 
     Venting tape  10  is used in conjunction with the manufacture of appliances  34  (FIG. 4) such as refrigerators or freezers. Appliance  34  includes a void  38  defined between an outer housing  40  and an inner casing  42 . Outer housing  40  is provided with a plurality of venting holes  32 . Venting tape  10  is used to effectively filter air and gas that is forced from within void  38  and through venting holes  32 , while preventing expandable foam  32  from escaping. It should be noted, however, that venting tape  10  can be used to effectively filter holes/apertures within other products such as home door panels, free standing office partition systems, and vehicle components, as well as numerous other applications that use injected expandable foams. 
     Polymeric film  12  (FIG. 1) is constructed of a polymeric material such as polyester or polypropylene depending upon the temperatures that will be encountered by the venting tape  10  in a particular application. Polymeric film  12  is approximately 10 microns in thickness, however, other thicknesses can be used. Perforations  14  are provided within polymeric film  12  at a density of between about  30  and  350  perforations per square inch. Preferably, about  330  perforations per square inch are provided. Each perforation  14  is between about 0.6-0.7 microns in diameter, however, other diameters can be substituted. The number of perforations 14 per square inch can be altered depending upon the expandable foam insulation to be used in a particular application. By altering the number of perforations  14 , the back pressure created by the air/gas as the foam expands is controlled to maximize filtering efficiencies and allow adequate filling of the void  38  (FIG.  4 ). 
     Polymeric film  12  is further provided with raised rings  20  formed about the perforations  14 . Rings  20  increase the effective thickness of polymeric film  12  about each and every perforation  14 , thereby increasing the effective tear strength of the polymeric film  12  in those regions. The increased tear strength allows venting tape  10  to withstand higher pressures created by the expandable foam  36  contacting venting tape  10  before tearing or failing. Perforations  14  and the associated rings  20  are created by a flame perforation process. 
     Adhesive layer  16  (FIGS. 1 and 2) is applied to one side of polymeric film  12  and in a pattern enabling a substantial portion of perforations  14  to remain uncovered by adhesive layer  16 . More specifically, adhesive layer  16  is applied to polymeric film  12  in a spaced apart linear pattern along the length of polymeric film  12 . Adhesive layer  16  is constructed of a material that allows venting tape  10  to be permanently affixed to an interior surface of an appliance housing  40  (FIG.  4 ). Adhesive layer  16  is preferably applied in the form of a hot-melt adhesive. 
     Venting tape  10  may be further provided with a detachable release liner  18 , thus ensuring that adhesive layer  16  does not prematurely adhere to an unintended surface before being applied to the desired application. Release liner  18  is preferably constructed of a silicon coated paper, however, any suitable material may be used. 
     Venting tape  10  can be provided in the form of a continuous roll  21  (FIG.  2 ), whereby a length of venting tape  10  may be removed from the roll  22  for a given application. Roll  22  would be preferably sized for easy handling and manipulation during the application process. Alternatively, venting tape  10  could be pre-cut into a plug  23  (FIG. 3) having a particular geometrical shape and size corresponding with a particular application. 
     In application and operation, a length of venting tape  10  is removed from roll  21  corresponding to the requirements of a particular application. Release liner  18  is removed from polymeric film  12  to expose adhesive layer  16 . Polymeric film  12  is then applied over vent holes  32  within the interior of housing  40  of appliance  34 . Inner casing  42  is then inserted into housing  40  of appliance  34 . The expandable foam insulation  36  is then inserted between inner casing  42  and housing  40  thereby filling void  38  located therebetween. Venting tape  10  allows any gases associated with the expandable foam insulation  36  to exit vent holes  32  through perforations  14 , while retaining the expandable foam insulation  36  within void  38 , thereby allowing adequate and even filling of void  38 . 
     Venting tape  10  effectively reduces the costs associated with insulating appliances with an expandable foam insulation, by allowing air/gas to pass through vent holes  32  while preventing the passage of the expandable foam  36  as the expandable foam  36  expands to fill void  38  between inner casing  42  and outer housing  40 . Venting tape  10  can be cut on site to fit the specific dimensional requirements of a particular application. In addition, venting tape  10  can be easily installed within the outer housing  40  prior to assembly of outer housing  40  with inner casing  42 , thereby increasing manufacturing efficiency. 
     In the foregoing description, it will be readily appreciated by those skilled in the art that modifications may be made to the invention without departing from the concepts disclosed herein. Such modifications are to be considered as included in the following claims, unless these claims by their language expressly state otherwise.