Patent Document

FIELD OF THE INVENTION 
       [0001]    The subject invention relates to products formed of multiple layers of heat sealable materials. More particularly, the subject invention relates to products formed of multiple layers of heat sealable materials that are sealable at different temperatures in discrete areas of the product. 
       BACKGROUND OF THE INVENTION 
       [0002]    There are numerous products formed using heat sealable materials, including pouches and other containers. They are manufactured by heat sealing together different layers of the materials in multiple locations to achieve the various sizes and shapes desired. U.S. Pat. Nos. 5,536,542 and 5,484,375 generally disclose articles created by heat sealing polymeric layers together. 
         [0003]    It is often desirable to heat seal a multi-layer product in an area at a given temperature while not affecting one or more of the layers for design or functional reasons. Currently, this is achieved by introducing barrier layers such as paper, treating the layer that is to be protected with a lubricant or paint, or using a mechanical process to prevent a heat seal from occurring between certain layers in that area. This inevitably leads to additional multi-step processes which add time and cost to the manufacturing process. It would be advantageous to effect heat seals between layers in some areas at one temperature and in other areas at a different temperature without the need for additional intermediary steps. 
         [0004]    U.S. Pat. No. 6,996,951 discloses a flexible multi-compartment container with peelable seals and a method for making such a container. In one specific embodiment, the container includes multiple layers, with an outer layer having a higher melting temperature than an inner seal layer. U.S. Pat. No. 4,147,827 discloses a method for the production of heat sealable co-extruded films having a high melting point core layer coated on at least one side with a lower melting point skin layer. 
         [0005]    Thus, while the above references describe articles created by sealing together multiple layers of material, some of which may have different melting temperatures, none of them discloses, teaches or suggests a product formed of multiple layers that are heat sealed together wherein, in some areas, the materials forming the product are heat sealable at a lower temperature, and in other areas, the materials forming the product are heat sealable at a higher temperature, thereby allowing for heat sealing of discrete areas of the product in discrete steps. 
       SUMMARY OF THE INVENTION 
       [0006]    It is therefore an object of the present invention to provide an improved process for producing articles formed of multiple layers of heat sealable material, which accommodates the heat sealing of discrete areas of the product in discrete steps. 
         [0007]    It is a further object of the present invention to provide such an improved process which eliminates the need for intermediary steps within the process to impede heat sealing between layers in certain areas, where heat seals are not desired, to make the process more efficient and cost effective. 
         [0008]    The subject invention results from the realization, in part, that a more time and cost effective process for producing articles formed of multiple layers of heat sealable material can be achieved by providing a process wherein certain layers of the product are heat sealable at a lower temperature, and in other areas, certain layers of the product are heat sealable at a higher temperature. 
         [0009]    The subject invention, however, in other embodiments, need not achieve all these objectives and the claims hereof should not be limited to structures or methods capable of achieving these objectives. 
         [0010]    The subject invention features an article of manufacture comprising at least three layers of heat sealable material. There is at least one first heat seal between at least two of the layers in a first area and effected at a first temperature. Also, there is least one second heat seal between at least two of the layers, wherein at least one these two layers is distinct from the two layers joined by the first heat seal. This second heat seal is in a second area and is effected at a second temperature that is different than the first temperature, thereby allowing for heat sealing of discrete areas of the article in discrete steps. 
         [0011]    In one example, the at least three layers of heat sealable material comprise at least one laminate sheet. This sheet comprises a first face of material which is sealable at the first temperature and a second face of material that is sealable at the second temperature. 
         [0012]    In another example, the article of manufacture is a flexible ported pouch. Here, the least three layers of heat sealable material comprise two pouch layers with the first heat seal therebetween and two port layers with the second heat seal therebetween. 
         [0013]    In still another example, the article of manufacture is a dual layer baffle system. In this embodiment, the at least three layers of heat sealable material comprise two exterior layers connected to a plurality of baffles by a plurality of first heat seals, and a plurality of two baffle layers with the second heat seal there between. 
         [0014]    The subject invention also features a method for forming an article of manufacture. The method comprises the steps of providing at least three layers of heat sealable material. At least one layer of the at least three layers and at least one opposing layer of the at least three layers are heated to a first temperature in a first area to effect at least one first heat seal. Then, at least one layer of the at least three layers and at least one opposing layer of the at least three layers are heated to a second temperature, wherein the second temperature is different from the first temperature. This forms at least one second heat seal in a second area, thereby allowing for heat sealing of discrete areas of the article in discrete steps. 
         [0015]    In one example of this process, the at least three layers of heat sealable material comprise at least one laminate sheet. This sheet comprises a first face of material sealable at the first temperature and a second face of material sealable at the second temperature. 
         [0016]    The subject invention also features a flexible ported pouch with an interior. In an exemplary embodiment, the pouch comprises a first pouch sheet and a second pouch sheet and is formed by a first heat seal at a first temperature around a periphery of the first and second pouch sheets. This first heat seal has at least one gap having an opening spaced from the first heat seal to provide a channel between the first pouch sheet and the second pouch sheet. There is a port that is interposed between the first pouch sheet and the second pouch sheet, and is in communication with the interior of the pouch. This port comprises a first port sheet and a second port sheet, and is formed by a second and third heat seal along the longitudinal edges of the first and second port sheets at a second temperature wherein the second temperature is higher than the first temperature. The first and second port sheets are further heat sealed to the pouch where the first and second port sheets intersect with the periphery of the first and second pouch sheets at the first temperature. The difference in sealing temperatures allows the port to be sealed to the pouch without the interior of port also being sealed. 
         [0017]    Also, in the exemplary embodiment of the flexible ported pouch, the first and second port sheets are laminates comprising a first face sealable at the first temperature and a second face sealable at the second temperature. The first face forms the exterior of the port. The first face is sealable at a lower temperature so this allows the port to be sealed to the pouch at the point of intersection at the low temperature while leaving the interior of the port unsealed at this intersection. 
         [0018]    In other aspects of the present invention, the flexible pouch configuration can also be achieved by substituting the first and second pouch sheets with a single pouch sheet, folding it over on an axis, and effecting the first heat seal at the first temperature around the open pouch edges that are formed. Similarly, the flexible port configuration can be achieved by substituting the first and second port sheets with a single port sheet folded about an axis and replacing the second and third heat seals with a single heat seal at the second temperature along the open longitudinal edge. The single sheet port configuration can also feature a single port sheet comprising a laminate. This laminate comprises a first face sealable at the first temperature and a second face sealable at the second temperature with the first face forming the exterior of the port. 
         [0019]    The subject invention further features a method of manufacturing a flexible ported pouch. The method comprises the steps of providing a first and second port sheet of heat sealable material in parallel. The first and second port sheets are then heated along their longitudinal edges to a first temperature to effect a first and second heat seal to form a port with an exterior and an interior. First and second pouch sheets of heat sealable material are then provided in parallel. The port is introduced by interposition between the first and second pouch sheets. Finally, a periphery of the first pouch sheet, the second pouch sheet and the exterior of the port, where the exterior of the port intersects with the periphery of the first and second pouch sheets, is heated to a second temperature. The second temperature is lower than the first temperature and effects a third heat seal without sealing the interior of the port at the intersection of the periphery of the pouch. 
         [0020]    The subject method can also be executed by substituting the first and second port sheets with a single port sheet and folding it upon an axis. The open longitudinal edge can then be heated to the first temperature to effect a first heat seal to replace the first and second heat seals of the exemplary method. Similarly, the first and second pouch sheets can be replaced by a single pouch sheet folded upon an axis and sealed along the open edges at the second temperature. 
         [0021]    The subject invention also includes a dual layer film baffle system. The exemplary embodiment of the baffle system comprises a first and second sheet of heat sealable material. There is then a plurality of baffle elements interposed between the first and second sheets. These baffle elements comprise a third sheet of heat sealable material heat sealed at a first temperature along one edge of the third sheet and latitudinally across the first sheet. A fourth sheet of heat sealable material is heat sealed at the first temperature along one edge of the fourth sheet and latitudinally across the second sheet. The third and fourth sheets are further heat sealed together along their common edge at a second temperature wherein the second temperature is higher than the first temperature. 
         [0022]    In the exemplary embodiment of the baffle system, the first and second sheets of heat sealable material are low temperature heat sealing material and the third and fourth sheets of heat sealable material are laminates comprising a first face of high temperature sealing material and a second face of low temperature sealing material. 
         [0023]    The subject invention also features a method of manufacturing a dual layer baffle system. The method comprises the steps of providing a first and second sheet of heat sealable material in parallel. The sheets are then heated to a first temperature latitudinally across the first and second sheets at a longitudinal interval to effect a plurality of first heat seals. The first and second sheets are then perforated latitudinally across the sheets at the longitudinal interval effecting a plurality of perforated lines. A third sheet of heat sealable material is then introduced to the exterior of the first sheet. A fourth sheet of heat sealable material is then introduced to the exterior of the second sheet. Then, the third sheet, the first sheet, the fourth sheet and the second sheet are heated to a second temperature, wherein the second temperature is lower than the first temperature, latitudinally across the sheets at the longitudinal interval, effecting a plurality of second heat seals between the fourth sheet and the first sheet and a plurality of third heat seals between the third sheet and the second sheet. Finally, the fourth sheet and third sheet are spread apart, thereby separating the first and second sheet along the perforated lines to effect baffles between the fourth sheet and the third sheet. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0024]    Other objects, features and advantages will occur to those skilled in the art from the following description of an exemplary embodiment and the accompanying drawings, in which: 
           [0025]      FIG. 1  shows a schematic cross sectional view of an article of manufacture consisting of multiple layers of heat sealable material and multiple heat seals; 
           [0026]      FIG. 2  shows a perspective view of a portion of an assembled flexible ported pouch employing the multiple layers and multiple heat seals shown in  FIG. 1 ; 
           [0027]      FIG. 3  shows a greatly enlarged schematic cross sectional view of the port opening of an assembled flexible ported pouch of  FIG. 2 ; 
           [0028]      FIG. 4  shows a greatly enlarged schematic cross sectional view of the port opening of the exemplary embodiment of an assembled flexible ported pouch of  FIG. 2  wherein the port sheets are laminates; 
           [0029]      FIG. 5  shows a two dimensional side view of a dual layer film baffle system manufacturing process schematic featuring the multiple layers of heat sealable material and multiple heat seals shown in  FIG. 1 ;  FIG. 2  is 
           [0030]      FIG. 6  shows a greatly enlarged schematic two dimensional view of the baffle sheets from the dual layer film baffle system schematic of  FIG. 5  as laminates; 
           [0031]      FIG. 7  shows a two dimensional overhead view of the dual layer film baffle system manufacturing process schematic of  FIG. 5 ; 
           [0032]      FIG. 8  shows a greatly enlarged schematic two dimensional view of the dual layer film baffle system schematic of  FIG. 5  as the exterior sheets are being spread apart; and 
           [0033]      FIG. 9  shows an enlarged perspective view of a finished dual layer film baffle system produced by the manufacturing process of  FIG. 5 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0034]    Aside from the exemplary embodiments disclosed below, this invention is capable of other embodiments and of being practiced or being carried out in various ways. Thus, it is to be understood that the invention is not limited in its application to the details of construction and the arrangements of components set forth in the following description or illustrated in the drawings. Moreover, the claims hereof are not to be read restrictively unless there is clear and convincing evidence manifesting a certain exclusion, restriction, or disclaimer. 
         [0035]    In general, the subject invention is heat sealing multiple layers of material at different temperatures at various locations. A sheet of material may be a laminate and have one face of material, or layer, with a heat sealing temperature that is higher than the heat sealing temperature of the opposite face of material, or layer. 
         [0036]    One embodiment of the subject invention is article of manufacture  2 ,  FIG. 1 . Sheet  5  is laminate where layer  6  and layer  7  are heat sealable at different temperatures. Heat seal  8  is formed by heating layer  3  and sheet  5  to a first temperature at which a seal between layer  3  and layer  6  is effected. Heat seal  9  is formed by heating layer  4  and sheet  5  to a second temperature, which is different than the first temperature, and at which a seal between layer  4  and layer  7  is effected. 
         [0037]    In one particular embodiment, flexible ported pouch  10 ,  FIG. 2 , has a top pouch sheet  20  and a bottom pouch sheet  22  each made of heat sealable material. In one exemplary embodiment, the material is Low Density Polyethylene (LDPE) and is heat sealable between 225-275 degrees F., but other heat sealing sheets or heat sealing laminates can be used. In some other embodiments, pouch sheets  20  and  22  may be a single heat sealable sheet or heat sealable laminate folded about an axis to create top sheet  20  and bottom pouch sheets  22 . 
         [0038]    Port  26 , also  FIG. 2 , has a top port sheet  30  and bottom port sheet  28  each made of heat sealable material. In the exemplary embodiment in  FIG. 4 , top port sheet  30  is a laminate having one layer  42  with a low sealing temperature and the opposite layer  44  having a high sealing temperature. Likewise, bottom port sheet  28  is a laminate having one layer  38  with a low sealing temperature and the opposite layer  40  having a high sealing temperature. In this exemplary embodiment, layers  38  and  42  which form the exterior face of port  26  are made of LDPE and are heat sealable between 225-275 degrees F. while layers  40  and  44  which form the interior of port  26  are made of High Density Polyethylene (HDPE) and are heat sealable between 325-375 degrees F. Other heat sealable sheets or heat sealable laminates may be used for port sheet  28  and port sheet  30  as long as the interior of port  26  is heat sealable at a temperature that is higher than the heat sealing temperature of pouch sheets  20  and  22 . This prevents the sealing of the interior of port  26  where it intersects with pouch  10  at gap  12 . Port sheet  28  and port sheet  30  may, in other embodiments, be a single heat sealable sheet or heat sealable laminate folded about an axis to create top port sheet  30  and bottom port sheet  28 . 
         [0039]    In  FIG. 2 , port  26  is interposed between top pouch sheet  20  and bottom pouch sheet  22  at gap  12 .  FIG. 3  shows port edge heat seal  32  and port edge heat seal  34  between top port sheet  30  and bottom port sheet  28 . In the exemplary embodiment in  FIG. 4 , layer  44  of top port sheet  30  and layer  40  of bottom port sheet  28  are heat sealed at port edge heat seals  32  and  34 . Preferably, these heat seals are effected between a temperature of 325-375 degrees F. In other embodiments, if port  26  is formed using a single sheet or laminate folded about an axis, only one heat seal would need to be effected along the open edge of the folded sheet. 
         [0040]    Top pouch sheet  20 ,  FIG. 2 , is heat sealed to bottom pouch sheet  22  along periphery heat seal  24  at a temperature which is lower than that of the temperature used to seal port  26  at port edge heat seals  32  and  34 . In  FIG. 3 , where periphery heat seal  24  intersects with port  26  at gap  12 , heat seal  36  is formed between top pouch sheet  20  and top port sheet  30  and heat seal  37  is formed between bottom pouch sheet  22  and bottom port sheet  28 . In the exemplary embodiment in  FIG. 4 , where periphery heat seal  24  intersects with port  26  at gap  12 , heat seal  36  is formed between top pouch sheet  20  and layer  42  of top port sheet  30  and heat seal  37  is formed between bottom pouch sheet  22  and layer  38  of bottom port sheet  28 . It is preferable that heat seals  24 ,  36  and  37  are effected at a temperature between 225-275 degrees F. This seals the exterior of port  26  to pouch  10  at gap  12  without sealing the interior of port  26  along gap  12 . 
         [0041]    The exemplary embodiment of a dual layer film baffle system manufacturing process  60  is shown in  FIG. 5 . Roll  70  dispenses heat sealable sheet  72  in parallel with heat sealable sheet  74  which is dispensed by roll  71 . In the exemplary embodiment, heat sealable sheet  72  and heat sealable sheet  74 ,  FIG. 6 , are laminates. Layers  73  and  76  are made of a low temperature heat sealable material, LDPE, and are sealable between a temperature of 225-275 degrees F. Layers  77  and  75  are made of a high temperature sealable material, HDPE, and are sealable between a temperature of 325-375 degrees F. 
         [0042]    Sheet  72  and sheet  74 ,  FIG. 5 , are brought together at high temperature and perforation station  78 . At this point, sheet  72  and sheet  74  are heated to create heat seal  79 ,  FIG. 7 , latitudinally across the sheets at some interval  81  dependent upon the desired length of baffles  90  and  91 ,  FIG. 8 . Interval  81  may, for example, be one inch. Also at station  78 ,  FIG. 5 , the now sealed sheets are perforated at interval  81  and immediately preceding heat seal  79  to create perforated line  80  across the sheets. 
         [0043]    Roll  82 ,  FIG. 5 , dispenses low temperature sheet  84  onto sheet  72  while roll  83  dispenses low temperature sheet  85  onto sheet  74 . Sheets  84  and  85  may be made of LDPE and are heat sealable at a temperature of 225-275 degrees F. The sheets are brought together at low temperature sealing station  88  where low temperature seal  86  is effected between sheet  84  and  72  and low temperature seal  87  is effected between sheets  85  and  74 . These low temperature seals also cross the sheets latitudinally and are spaced at interval  81 . 
         [0044]    Sheets  84  and  85 ,  FIG. 9 , are then spread apart. This causes baffle  90 ,  FIG. 8 , to separate from baffle  91  at perforated line  80 . The end result is a plurality of two piece baffles between sheets  84  and  85 . The two pieces of the baffle are joined to each other at high temperature seal  79  and joined to sheet  84  and  85  at low temperature seals  86  and  87 . 
         [0045]    Although specific features of the invention are shown in some drawings and not in others, this is for convenience only as each feature may be combined with any or all of the other features in accordance with the invention. The words “including”, “comprising”, “having”, and “with” as used herein are to be interpreted broadly and comprehensively and are not limited to any physical interconnection. Moreover, any embodiments disclosed in the subject application are not to be taken as the only possible embodiments. 
         [0046]    In addition, any amendment presented during the prosecution of the patent application for this patent is not a disclaimer of any claim element presented in the application as filed: those skilled in the art cannot reasonably be expected to draft a claim that would literally encompass all possible equivalents, many equivalents will be unforeseeable at the time of the amendment and are beyond a fair interpretation of what is to be surrendered (if anything), the rationale underlying the amendment may bear no more than a tangential relation to many equivalents, and/or there are many other reasons the applicant cannot be expected to describe certain insubstantial substitutes for any claim element amended. 
         [0047]    Other embodiments will occur to those skilled in the art and are within the following claims.

Technology Category: 7