Patent Publication Number: US-6339912-B1

Title: Easy open package for food items such as loaves of processed cheese

Description:
BACKGROUND OF THE INVENTION 
     The invention generally relates an easy open package for food items such as loaves of processed cheese. More specifically, the invention relates to a food package which employs a tear strip in combination with serrated film to provide a hermetically sealed, easy-open package. 
     It is desirable to hermetically seal food item packages such as loaves of processed cheese to preserve the food item. For this purpose film overwrap machines are available, such as the Hayssen 5000 Wrapper built by Hayssen, Inc., 225 Spartangreen, Duncan, S.C. (now owned by Paper Converting Machine Co., 2300 S. Ashland Ave., Green Bay, Wis.), and the Hart 3×12 Wrapper, built by Hart Design &amp; Mfg., Inc., 1940 Radisson Street, Green Bay. Hermetically sealed packages may not be easily opened, however. Film packages employing heat or pressure sealable tear strips to facilitate the opening of sealed packages are known. See, e.g., U.S. Pat. Nos. 3,170,619; 3,566,752; 3,909,330; 3,933,568; ,367,816; 4,498,274; 4,836,378; 4,848,649; 5,215,380; 5,704,481; and 5,899,333. Disadvantages remain with existing tear strip technology. Conventional overwrap machines known to use films with tear strips form packages with crimped extended ends, rather than flat ends, leaving air pockets at each end which promote contamination. Also, pulling on the tear strip may cause other portions of the film package to tear. Further, the tear strip may not be easily accessible, sometimes also resulting in the tearing of other portions of the film package during opening of the package, or the damage or contamination of the packaged item through puncture or other means. This may be undesirable in food packaging applications, or in applications where it is desired to re-pack portions of the unused food product. Finally, the film and/or tear strip may not permit easy and consistent opening of packages using a generally uniform force. 
     Accordingly, objects of the present invention include: the provision of a hermetically sealed food package, such as for loaves of processed cheese, that provides ready access to a tear strip; that permits easy package opening using a generally uniform force; and that limits or eliminates tearing of other portions of the film package, or contamination of the food item, during opening of the package. 
     DEFINITION OF CLAIM TERMS 
     The following terms are used in the claims of the patent as filed and are intended to have their broadest meaning consistent with the requirements of law. Where alternative meanings are possible, the broadest meaning is intended. All words used in the claims are intended to be used in the normal, customary usage of grammar and the English language. 
     tear resistance: the resistance a packaging film has to tearing in any given direction 
     sealing force: the force necessary to remove a tear strip, without tearing, from packaging film to which it has been applied by breaking the adhesive bond the tear strip has with the film 
     accessible end: a tear strip end which can be relatively easily grabbed and pulled manually by a consumer 
     tear strip: any strip of material affixed to a packaging film with a scaling force which is greater than the tear resistance of the film 
     hermetically sealed: a plastic food package with seals that exclude air and are leakproof at normal temperatures and atmospheric pressure to the extent the packaging film permits 
     film tearing force: the force necessary to tear the plastic film in any given direction 
     SUMMARY OF THE INVENTION 
     The objects mentioned above, as well as other objects, are solved by the present invention, which overcomes disadvantages of prior art food packages such as for loaves of processed cheese, while providing new advantages not believed associated with such food packages. 
     In one preferred embodiment, a process is provided for forming an easily opened, hermetically sealed package of a food item. A plastic film with a certain tear resistance and serrated edges is used. The tear strip is affixed to the film so that the tear strip is sealed to the film by a sealing force that is greater than the tear resistance of the film. The tear strip runs with or is adjacent to at least one accessible, unsealed end of the film, which is adjacent one or more of the serrated edges of the film. The plastic film is formed about the food item and sealed, resulting in a hermetically sealed package entirely enclosing the food item. When thus enclosed, a pulling force exerted on the at least one accessible end results in concentration of a film tearing force beginning at one of the one or more serrated edges of the film adjacent the at least one accessible end, resulting in tearing of the film in a direction generally toward the tear strip following by tearing of the film in a direction parallel to the tear strip, thereby allowing easy opening of the package without damaging the food item. 
     The food item may be any of various foods, such as loaves of processed cheese or other items. 
     In a preferred process embodiment, the package has two opposing ends. At least one of the opposing ends includes two pairs of opposing flaps. One of the two pairs of flaps of an opposing end is at least partially sealed to each other; at this time, the sides may be sealed. In a subsequent step, the other of the two pairs of flaps of the opposing end is at least partially sealed to each other, to thereby form a package end which is hermetically sealed. Two different sealing bars may be used to accomplish this. 
     In one preferred embodiment, at least one of the package ends has an unsealed ear portion formed using a seal bar with an aperture, and the at least one accessible end of the tear strip lies adjacent the unsealed ear portion. 
     Preferably, the tear strip is continuously affixed to the film as the film is advanced and prior to formation of the hermetically sealed package. However, any expedient manner for affixing the tear strip may be used. 
     In another preferred embodiment, an easily opened, hermetically sealed package for completely enclosing a food item is provided. A plastic film having a tear resistance and serrated edges is formed about the food item and sealed. Prior to or during this process, a tear strip is affixed to the film by a sealing force that is greater than the tear resistance of the film. The tear strip is adjacent to or associated with at least one accessible, unsealed end of the film, which is adjacent one or more of the serrated edges of the film. A pulling force exerted on the at least one accessible end results in concentration of a film tearing force beginning at one of the one or more serrated edges of the film adjacent the at least one accessible end, resulting in tearing of the film in a direction generally toward the tear strip following by tearing of the film in a direction generally along the tear strip, thereby allowing easy opening of the package without damaging the food item. 
     The package may have opposing ends as recited, and formed as indicated, above. In one preferred package configuration, the package is generally rectangular with four sides and two opposing ends, and the tear strip runs in a lengthwise direction along one or more sides of the package. One of the sides may be hermetically sealed using a lap seal. Each end of the package is hermetically sealed and lays substantially flat against an adjacent edge of the food item. 
     The plastic film may be made of various suitable films used in the food packaging industry, such as polypropylene. Any suitable film thickness may be used, such as in a range of between about 100-180 gauge or, more preferably, about 120 gauge. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The novel features which are characteristic of the invention are set forth in the appended claims. The invention itself, however, together with further objects and attendant advantages thereof, will be best understood by reference to the following description taken in connection with the accompanying drawings, in which: 
     FIG. 1 is a perspective view of a loaf of processed cheese that has been hermetically sealed in a package, according to the present invention; 
     FIG. 2 is a bottom perspective view of the processed cheese loaf being met by the film from underneath; 
     FIGS. 3-7 are end partial perspective views showing consecutive packaging steps in the preferred embodiment of the process of the present invention which results in the hermetically sealed package shown in FIG. 1; 
     FIG. 8 is a partial perspective end view illustrating the accessible tear strip of the preferred embodiment; 
     FIG. 9 is an enlarged partial perspective view showing removal of the tear strip of the package embodiment shown in FIG. 8 without rupture of the packaging film; 
     FIG. 10 is a partial perspective view of a conventional overwrap (Hayssen) machine modified for use with the present invention; 
     FIG. 11 is an enlarged perspective view of the circled portion (labeled  11 — 11 ) of FIG. 10; 
     FIG. 12 is a side view showing the direction of the bottom seal bar relative to the loaf; 
     FIGS. 13 and 14 are top views illustrating the sequential movement of the side sealing bars; 
     FIGS.  15  and  17 - 18  are partial sequential perspective views showing the process steps of one preferred embodiment of the present invention in which folding and sealing of the top and bottom end flaps is accomplished; 
     FIG. 16 is a cross-sectional view taken along sections lines  16 — 16  of FIG. 15; and 
     FIGS. 19 and 20 are top and side views, respectively, of a portion of the overwrap machine which forms the preferred embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Set forth below is a description of what are currently believed to be the preferred embodiments and/or best examples of the invention claimed. Future and present alternatives and modifications to these preferred embodiments are contemplated. Any alternatives or modifications which make insubstantial changes in function, in purpose, in structure or in result arc intended to be covered by the claims of this patent. 
     FIG. 1 illustrates a hermetically sealed package, generally designated with reference numeral  20 , of an (e.g.) 3- or 5-pound loaf of processed cheese made according to the present invention. Of course, it will be understood that the present invention may be adapted for use in packaging items other than loaves of processed cheese, such as cheese singles, as well as chocolate, lasagna, biscuits, etc. 
     The exemplary process for forming the hermetically sealed package of the present invention is now described with regard to drawings generally showing a conventional overwrap machine available from Hayssen (now Paper Converting) which has been modified in the manner discussed below. The film typically used for packaging loaves has also been modified to include serrated edges and a tear strip, as further discussed below. 
     In overview, and referring first to FIGS. 1-9, the exemplary process of the present invention provides a hermetically sealed rectangular package  20  with four long sides  20 A and two ends  20 B, as follows. Referring to FIGS. 2-3, a suitable packaging film  22  is arranged adjacent the item to be packaged and folded longitudinally about the loaf as shown. Film  22  has serrated ends  22 A which facilitate tearing of the film, as further explained below. The film is then sealed along its longitudinal edge  25  (parallel to the length of cheese loaf  24 ) using either a lap or fin seal, although a lap seal is typical. At this same time, side flaps  27 A,  27 B of each end portion are folded over and sealed (FIGS.  4 - 5 ). Then, top and bottom flaps  29 A,  29 B of each end portion are folded over and sealed (FIGS.  6 - 7 ), leaving an unsealed ear portion  33  (FIG. 8) which is easily accessible. A tear strip  30  is adhesively attached to the film before the folding step and as the film is unrolled, and extends through the unsealed ear portion  33 . 
     The overwrap machine used in the preferred process of the present invention is modified in certain important respects from conventional overwrap machines used for the packaging of loaves of processed cheese, as now described. Conventional overwrap machines used for sealing the ends  20 A of packaged loaves of processed cheese employ a single pair of flat heated sealer bars, roughly equivalent in size to the height and width dimensions of the package ends. This single pair of sealer bars is used, at a single time, to hermetically seal each end flap of the package after the side flaps and the top and bottom flaps have been folded over. With the present invention, as shown best in FIGS. 5,  7 ,  13 - 14  and  19 - 20 , two pairs of heated sealer bars (together with a modified non-continuous cover plate, as shown) are used. The first pair of heated sealer bars  35 , preferably dimensioned roughly as shown in FIG. 5 (i.e., having a width generally coextensive with or greater than the package end width, and a height slightly less, on each top and bottom edge, than the length of the package end, such as ¼-inch less), seals the side flaps together. The second pair of heated sealer bars  37 , again dimensioned roughly as shown (i.e., with dimensions coextensive or greater than the dimensions of the package end), seal top and bottom flaps  29 A,  29 B to each other and to side flaps  27 A,  27 B such that hermetic seals form wherever the plastic film overlaps in this region. Due to the relief or cut-out section  37 A of bar  37 , with radiused edges  37 B, which results in unsealed ear portion  33 , the side flaps  27 A,  27 B must first be sealed in the area of this relief section  37 A; otherwise, a hermetic seal cannot be formed at the ends of the package. In other words, unlike conventional overwrap machines, the modified overwrap machine used in the preferred process of the present invention provides a hermetically sealed package end with an accessible, unsealed ear portion  33 , as shown in FIG.  8 . 
     Film  22  is also modified in an important manner from the typical film used in conventional overwrap machines for packaging loaves of processed cheese. Thus, referring to FIGS. 2-3, film  22  includes serrated ends  22 A. Serrated ends  22 A provide points of focus to facilitate tearing of the film. Referring to FIG. 8, the film with serrated edges  22 A is easily torn in a direction generally toward tear strip  30 , at which point uniform tearing generally along tear strip  30  commences, as shown in FIG.  9 . (The tear may be wider, in some cases, than shown, but will be generally parallel and adjacent the tear strip.) Accordingly, the package  20  may be easily opened without damaging or unduly contaminating the food item simply by manually pulling on accessible end  33 . 
     Tear strip  30  is preferably a pressure sensitive tape which adheres to film  22  using an adhesive. Tear strip  30  has a sealing force which is greater than the tear resistance of the film. A suitable tear strip, known as Supastrip® XL Teartape, is available from P.P. Payne, Inc. of Ashland, Va. (mail@pppayne.com); suitable dispensing apparatus is also available form P.P. Payne and/or Supastrip International. 
     Referring now to FIG. 10, a roll  38  of tear strip  30  may be unwound and tear strip  30  applied to film  22  as the film is unwound from film roller  40 . As shown, the tension of the film as it moves over rollers  41 , for example, applies sufficient pressure to cause tear strip  30  to adhere to the underside of film  22 . Opposing film feed rolls  83 A and  83 B rotate, pinch the film and help keep the film moving in a continuous forward direction. Referring to FIGS. 10 and 11, loaf  20  is moved vertically upward to meet the film, and is thus wrapped about the length of the cheese loaf. Shoe  70  moves horizontally on dead plate  86 ;and cooperates with tucker plates  71  and  77  to tuck the sides of the film about the underside of the loaf in an overlapping fashion. Heated sealer bar  50  (see FIGS. 12 and 19) then moves vertically upward to form into a hermetical lap seal the film overlap region thus formed on the underside of the loaf. At the same time, vertical end flaps  27 A and  27 B are being folded by folding shoe  75  (see FIG. 11) and sealed by the first set of seal bars  35 . 
     Next, the semi-packaged loaf, with open end flaps, is moved horizontally through a folding apparatus, such as shown in FIGS. 15-17 and  20 . The upwardly sloping taper of plate  80  acts to fold the bottom end flap upwardly, as shown in FIGS. 15 AND 16. The downwardly sloping taper of plate  80  then acts to fold the upper end flap downwardly, as shown in FIG.  17 . Immediately after exiting plate  80 , heated scaling bars are used to hermetically seal the end seals, as shown in FIGS. 7 and 18, to form the completed, hermetically sealed package  20 , with accessible tear strip  30  and substantially flat end portions  20 B that leave little room for unwanted air pockets. 
     It will be understood that the sealer bars mentioned here should be heated to temperatures sufficient to activate the adhesive within the packaging film, and to form a suitable hermetic seal. Any suitable packaging film known may be used, such as polypropylene. Film thicknesses may vary, but are preferably about 100-180 gauge and, more preferably, about 120 gauge such as for the processed cheese loaf application. 
     The above description is not intended to limit the meaning of the words used in the following claims that define the invention. For example, it will be understood that other wrapping machines not specifically mentioned here that accomplish the same general folding and packaging operations may do so in substantially different ways, while still providing a hermetically sealed package within the principles of the present invention. Rather, it is contemplated that future modifications in structure, function or result will exist that are not substantial changes and that all such insubstantial changes in what is claimed are intended to be covered by the claims.