Abstract:
An elongate flattened thermoplastic tube has an inflation edge and an opposite edge. The tube includes spaced transverse seals that define sides of pouches. The tube includes lines of weakness that allow adjacent dunnage units to be separated. A frangible line of connection is disposed in one two superposed layers of the tube proximate to the inflation edge. This frangible connection may be broken to permit inflation of the inflatable pouches.

Description:
RELATED APPLICATIONS  
       [0001]    The present application is a divisional application of U.S. application Ser. No. 12/259,419, filed Oct. 28, 2008 which claims the benefit of U.S. Provisional patent application Ser. No. 60/983,940, filed Oct. 31, 2007 for WEB AND METHOD FOR MAKING FLUID FILLED UNITS, the entire disclosures of which are fully incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION  
       [0002]    The present application relates to fluid filled units and more particularly to plastic webs of interconnected pouches and to processes of converting interconnected pouches to fluid filled units. 
       BACKGROUND  
       [0003]    Machines for forming and filling dunnage units from sheets of plastic are known. Machines which produce dunnage units by inflating preformed pouches in a preformed web are also known. For many applications, machines which utilize preformed webs are preferred. 
         [0004]    Typically, the entire length of sides of adjacent dunnage units formed from a preformed web are connected by perforations. In prior art webs, these perforations extend all the way to an inflation edge of the web. 
       SUMMARY 
       [0005]    The present invention relates to plastic webs of interconnected pouches and processes of converting interconnected pouches to at least one row of dunnage units. In one embodiment, the web is an elongate flattened thermoplastic tube having an inflation edge and an opposite edge. The tube includes spaced transverse seals that define sides of pouches. A frangible line of connection is disposed in one superposed layers of the tube proximate to the inflation edge. This frangible connection may be broken to permit inflation of the inflatable pouches. 
         [0006]    Further advantages and benefits will become apparent to those skilled in the art after considering the following description and appended claims in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]      FIG. 1  illustrates a web for making fluid filled units; 
           [0008]      FIG. 2  illustrates a web for making fluid filled units; 
           [0009]      FIG. 2A  illustrates a web for making fluid filled units; 
           [0010]      FIG. 3  illustrates a web with pouches inflated and sealed to form fluid filled units; 
           [0011]      FIG. 4  illustrates a web for making fluid filled units; 
           [0012]      FIG. 5  illustrates a web for making fluid filled units; 
           [0013]      FIG. 6  illustrates a web for making fluid filled units; 
           [0014]      FIG. 7A  schematically illustrates a plan view of a process and machine for converting web pouches to fluid filled units; 
           [0015]      FIG. 7B  schematically illustrates a plan view of a process and machine for converting web pouches to fluid filled units; 
           [0016]      FIG. 8A  schematically illustrates an elevational view of the process and machine for converting web pouches to fluid filled units; 
           [0017]      FIG. 8B  schematically illustrates an elevational view of the process and machine for converting web pouches to fluid filled units; 
           [0018]      FIG. 9  illustrates a process for converting web pouches to fluid filled units; 
           [0019]      FIG. 10  illustrates a web for making fluid filled units; 
           [0020]      FIG. 10A  illustrates a web for making fluid filled units; 
           [0021]      FIG. 11  illustrates a web of pouches inflated and sealed to form fluid filled units; and 
           [0022]      FIG. 12  schematically illustrates a plan view of a cutter for opening the inflation edge of a web. 
       
    
    
     DETAILED DESCRIPTION 
       [0023]    Referring to  FIGS. 1 and 2 , exemplary illustrations of webs  10  of inflatable pouches  12  are shown. The webs  10  includes a top elongated layer of plastic  14  superposed onto a bottom layer of plastic  16 . The layers are connected together along spaced edges, referred to as the inflation edge  18  and the opposite edge  20 . In the example illustrated by  FIG. 1 , each edge  18 ,  20  is either a fold or a seal that connects the superposed layers  14 ,  16  along the edges  18 ,  20 . The connection at the opposite edge  20  is illustrated as a hermetic seal and the connection at the inflation edge  18  is illustrated as a fold in  FIG. 1 . However, the fold and the seal could be reversed or both of the connections could be seals in the  FIG. 1  embodiment. 
         [0024]    In the example illustrated by  FIG. 2 , the inflation edge  18  comprises a frangible connection  21  and the opposite edge  20  is a hermetic seal. The illustrated frangible connection  21  is a line of perforations. The size of the perforations is exaggerated to clarify  FIG. 2 . The frangible connection  21  may be formed by folding the inflation edge  18  and pulling the inflation edge over a serration forming wheel (not shown).  FIG. 2A  illustrates a web  10  of inflatable pouches  12  in which a frangible connection  21 ′ is present in one of the superposed layers, in the described embodiment layer  14 , at a location offset from the inflation edge  18  by a distance D 4 . In an exemplary embodiment, the distance D 4  is between 0.075 and 0.2 inches, in an exemplary embodiment between 0.09375 and 0.15625 inches. The frangible connection can be formed in a wide variety of different ways any of which can be used. For example, the frangible connection  21 ′ can be formed by pulling the web over a serration forming wheel (not shown) prior to folding the inflation edge or by providing a serration backing plate (not shown) interposed between the layers where the serration forming wheel contacts the web so that only a single layer is acted on by the wheel. 
         [0025]    Referring to  FIGS. 1 ,  2 ,  2 A a plurality of longitudinally spaced, transverse seals  22  join the top and bottom layers  14 ,  16 . Generally, each transverse seal  22  extends from the opposite edge  20  to within a short distance of the inflation edge  18 . Spaced pairs of lines of perforations  24 ,  26  extend through the top and bottom layers terminating a short distance from the edges  18 ,  20  respectively. A gap forming area  28  extends between each associated pair of lines of perforations  24 ,  26 . The gap forming area  28  opens to form a gap  13  when the pouches are inflated (see  FIG. 3 ). 
         [0026]    A gap forming area  28  denotes an area, preferably linear in shape, that will rupture or otherwise separate when exposed to a predetermined inflation force. The magnitude of the inflation force is less than the magnitude of the force needed to rupture or separate the spaced apart lines of perforations  24 ,  26 . The gap forming area  28  can take on a number of embodiments, as will be discussed below. Any method that produces an area between the spaced apart lines of perforations  24 ,  26  that ruptures or otherwise separates at a force lower than a force needed to rupture or separate spaced lines of perforations  24 ,  26  may be employed to make the gap forming area  28 . 
         [0027]    Referring to  FIG. 3 , the web  10  of pouches  12  ( FIGS. 1 ,  2 ,  2 A) is inflated and sealed to form a row  11  of dunnage units  12 ′. The formed dunnage units  12 ′ are configured to be much easier to separate from one another than prior art arrays of dunnage units. In the exemplary embodiment of  FIG. 3 , each adjacent pair of dunnage units  12 ′ is connected together by a pair of spaced apart lines of perforations  24 ,  26 . The spaced apart lines of perforations  24 ,  26  are spaced apart by a gap  13 . A single row  11  of dunnage units  12 ′ can be graphically described as being in a “ladder” configuration. This configuration makes separating two adjacent dunnage units  12 ′ much easier than separating prior art arrays of dunnage units. To separate a pair of adjacent dunnage units  12 , a worker simply inserts an object or objects, such as a hand or hands, into the gap  13  and pulls one dunnage unit  12 ′ away from the other dunnage unit  12 ′. In the alternative, a mechanical system can be used to separate dunnage units  12 ′. A machine can be configured to insert an object between adjacent dunnage units  12 ′ and apply a force to separate the units 
         [0028]    Referring to  FIGS. 1-3 , prior to conversion to a dunnage unit, a pouch is typically hermetically sealed on three sides, leaving one side open to allow for inflation. Once the pouch is inflated, the inflation opening is hermetically sealed and the dunnage unit is formed. During the inflation process, as the volume of the pouch increases the sides of the pouch have a tendency to draw inward. Drawing the sides of the pouches inward will shorten the length of the sides of the pouch unless the sides of the pouch are constrained. In this application, the term foreshortening refers to the tendency of the length of a pouch side to shorten as the pouch is inflated. In prior art webs, the sides of the pouch are restrained, because sides of adjacent pouches are connected by lines of perforations that extend along the entire length of the pouches and remain intact during and after inflation. The foreshortening of the unrestrained sides, such as the inflation opening, may not be uniform. Restraining the sides of adjacent connected pouches can cause undesirable inflation induced stresses. These undesirable stresses caused because sides of adjacent pouches are connected and restrained, thus, limiting inflation and causing wrinkles to develop in the layers at the unrestrained inflation opening. The wrinkles can extend into a section of the inflation opening to be sealed to complete the dunnage unit, which may comprise the seal. One reason the seal can be compromised is that wrinkling can cause sections of the layers  14 ,  16  to fold on top of one another. A sealing station of a dunnage machine is typically set to apply the appropriate amount of heat to seal two layers of material. The sealing of multiple layers of material in the area of a wrinkle results in a seal that is weaker than remaining seal areas and may result in a small leak or tendency to rupture at loads lower than loads at which the dunnage units is designed to rupture. 
         [0029]    In the embodiment illustrated by  FIG. 3 , the gap forming area  28 , produces a gap  13  between adjacent pouches upon inflation. The gap allows foreshortening of the connected pouch sides and thereby reduces the undesirable stresses that are introduced during inflation as compared with prior art webs. In addition, the web with a gap  13  facilitates fuller inflation of each pouch. The gap  13  maintains the inflation opening substantially free of wrinkles as the inflation opening is sealed to convert the inflated pouches to a dunnage units. 
         [0030]    The illustrated web  10  is constructed from a heat sealable plastic film, such as polyethylene. The web  10  is designed to accommodate a process for inflating each pouch  12  in the web to create a row or ladder  11  of dunnage units  12 ′. The gap forming area  28  creates a gap  13  between dunnage units  12 ′, which facilitate a efficient and effective process for separating adjacent dunnage units  12 ′ in the row or ladder  11 . 
         [0031]    In the example illustrated by  FIG. 4 , the gap forming area  28  defined by the web  10 ′ includes an easily breakable line of perforations  29  between the spaced lines of perforations  24 ,  26 . The force needed to rupture or separate the line of perforations  29  is less than the force needed to separate the perforations  24 ,  26  extending inward of the web edges  18 ,  20 . Each pair of perforations  24 ,  26  and associated more easily breakable line of perforations  29  divide the transverse seal  22  into two transverse sections. As a pouch  12  is inflated, the line of perforation  29  begins to rupture or separate leading to the development of a gap  13  between the produced dunnage units  12 ′ (See  FIG. 3 ). Once the pouch  12  is fully inflated, the line of perforations  29  is fully or nearly fully ruptured; however the perforations  24 ,  26  at the edges remain intact. These perforations  24 ,  26  are ruptured or separated when a worker or automated process mechanically separates the perforations  24 ,  26 . 
         [0032]      FIG. 5  illustrates another embodiment of the web  10 ″. In this embodiment the gap forming area  28  comprises an elongated cut  31  through both layers of material  14 ,  16 . The cut  31  extends between each associated pair of lines of perforations  24 ,  26 . In the embodiment illustrated by  FIG. 5 , pairs  30  of transverse seals  22 ′ extend from the opposite edge  20  to within a short distance of the inflation edge  18 . Each of the pairs of lines of perforations  24 ,  26  and corresponding cuts  31  are between an associated pair of transverse seals  30 . It should be readily apparent that the seal  22  shown in  FIG. 4  could be used with the cut  31  shown in  FIG. 5 . It should also be readily apparent that the line of perforations shown in  FIG. 4  could be used with the transverse seals  22 ′ shown in  FIG. 5 . It should be additionally apparent that any gap forming area  28  can be used with either of the transverse seal configurations  22 ,  22 ′ shown in  FIGS. 4 and 5 . 
         [0033]      FIG. 6  illustrates a further embodiment of the web  10 ′″. In this embodiment, the gap forming area  28  comprises at least two elongated cuts  32 , separated by light connections of plastic  36 , also referred to as “ticks.” These connections  36  hold transverse edges  38 ,  40  of the pouches  12  together to ease handling of the web  10 , such as handling required during installation of the web  10  into a dunnage machine. As the pouches  12  are inflated, the connections  36  rupture or otherwise break resulting in a gap  13  between the spaced pairs of perforations  24 ,  26 . This gap  13  allows for full inflation and reduces the stresses in the layers at the seal site normally caused by the foreshortening and restrictions on foreshortening of webs in the prior art. The reduced stress in the layers inhibits wrinkles along the inflation opening to be sealed. 
         [0034]    Other methods of creating a gap forming area not specifically disclosed are with the scope of the present application. Any area that separates and forms a gap between adjacent pouches as pouches  12  in a web  10  are inflated are contemplated by this, disclosure. 
         [0035]      FIG. 3 , illustrates a length of the web  10 ,  10 ′,  10 ″ or  10 ′″ after it has been inflated and sealed to form dunnage units  12 ′. An inflation seal  42 , the transverse seals  22  and an opposite edge seal  44  hermetically seal the top and bottom layers. The side edges  38 ,  40  of the formed dunnage units are separated to form a gap  13 . Each pair of adjacent dunnage units  12 ′ are connected together by the pair of spaced apart lines of perforations  24 ,  26 . The gap  13  extends between the pair of spaced apart lines of perforations  24 ,  26 . The array of dunnage units  12 ′ is a single row of dunnage units in a “ladder” configuration. The lines of perforations  24 ,  26  are configured to be easily breakable by a worker or automated system. To separate a pair of adjacent units  12 ′, a worker inserts an object, such as the worker&#39;s hand or hands into the gap  13 . The worker then grasps one or both of the adjacent dunnage units  12 ′ and pulls the adjacent dunnage units  12 ′ relatively apart as indicated by arrows  43   a ,  43   b . The lines of perforation  24 ,  26  rupture or otherwise separate and the two adjacent dunnage units  12 ′ are separated. The existence of the gap  13  also results in reduced stresses in the area of the inflation seal  42  at the time of sealing and accommodates increased inflation volume of the dunnage units  12 ′ as compared with prior inflated dunnage units. 
         [0036]    In one embodiment, the line of perforations  24  that extends from the opposite edge  20  is omitted. In this embodiment, the gap forming area  28  extends from the inflation edge line of perforations  26  to the opposite edge. In this embodiment, the gap  13  extends from the inflation edge line of perforations  26  to the opposite edge  20 . 
         [0037]    The connection of the layers  14 ,  16  at the inflation edge  18  can be any connection that is maintained between layers  14 ,  16  prior to the web  10  being processed to create dunnage units  12 ′. In the embodiment illustrated by  FIGS. 1 and 2A , the connection is a fold. In the embodiment illustrated by  FIG. 2 , the connection is a line of perforations  21 . One method of producing such a web is to fold a continuous layer of plastic onto itself and create a fold at what is to become the inflation edge  18 , A tool can be placed in contact with the fold to create a line of perforation. The opposite edge  20  can be hermetically sealed and the transverse hermetic seals  22  can be added along with the separated lines of perforations  24 ,  26  extending inward from the inflation and opposite edges  18 ,  20 . The web shown in  FIG. 1  can be produced in the same manner, except the perforations are not added. 
         [0038]      FIGS. 7A ,  7 B,  8 A,  8 B and  9  schematically illustrate a machine  50  and process of converting the webs  10 ,  10 ′,  10 ″ and  10 ′″ to dunnage units  12 ′. Referring to  FIGS. 7A ,  7 B,  8 A and  8 B, a web  10 ,  10 ′,  10 ″ or  10 ′″ is routed from a supply  52  ( FIGS. 8A and 8B ) to and around a pair of elongated, transversely extending guide rollers  54 . The guide rollers  54  keep the web taught as the web  10  is pulled through the machine  50 . At location A, the web pouches are uninflated. In the embodiment illustrated by  FIG. 5 , pouch edges  38 ,  40  defined by the cut  31  are close to one another at location A. In the embodiments illustrated by  FIGS. 4 and 6 , the frangible connections  29 ,  36  are of sufficient strength to remain intact at location A. 
         [0039]    A longitudinally extending guide pin  56  is disposed in the web at station B. The guide pin  56  is disposed in a pocket bounded by the top and bottom layers  14 ,  16 , the inflation edge  18 , and ends of the transverse seals  22 . The guide pin  56  aligns the web as it is pulled through the machine. A separator, such as a knife cutter  58  ( FIGS. 7A and 8A ), or a blunt surface  58 ′ ( FIGS. 7B and 8B ) is present on the guide pin  56 . In the embodiment illustrated by  FIGS. 7A and 8A  the knife cutter  58  extends from the guide pin  56 . The knife cutter  58  is used to cut the inflation edge  18  illustrated by  FIG. 1 , but could also be used to cut the perforated inflation edge  18  illustrated by  FIG. 2 . The cutter  58  slits the inflation edge  18  as the web moves through the machine  50  to provide inflation openings  59  (See  FIG. 9 ) into the pouches, while leaving the pouches otherwise imperforate. A variation of this would have the cutter  58  cutting either layer  14 ,  16 , or both near the inflation edge  18 . In the embodiment illustrated by  FIGS. 7B and 8B , the guide pin  56  defines a separator in the form of the blunt surface  58 ′ and the knife cutter is omitted. The blunt surface  58 ′ is used to break the perforated inflation edge illustrated by  FIG. 2 . The blunt surface  58 ′ breaks open the inflation edge  18  as the web moves through the machine to provide the inflation openings into the pouches  12 . 
         [0040]    A blower  60  is positioned after the cutter  58  or blunt surface  58 ′ in station B. The blower  60  inflates the web pouches as the web moves past the blower. Referring to  FIG. 9 , the web pouches are opened and inflated at station B. The seal edges  38 ,  40  spread apart as indicated by arrows  61  ( FIGS. 7A ,  7 B and  9 ) as the web pouches are inflated. In the embodiment illustrated by  FIGS. 4 and 6 , the frangible connections  29 ,  36  maintain successive pouches substantially aligned as the web is fed to the filling station B. The frangible connections are sufficiently weak that the connection between a pouch that has been opened for inflation and is being inflated at the fill station B and an adjacent, successive (or preceding) pouch will rupture as the pouch at the fill station is inflated. The spreading of the edges  38 ,  40  forms a row of inflated dunnage units in a ladder configuration and increases the volume of the air that can enter the pouches. The spreading also reduces the stresses imparted to the web adjacent the inflation side edge  18  where it is to be sealed. 
         [0041]    The inflation seal  42  is formed at station C by a sealing assembly  62  to complete each dunnage unit. In the exemplary embodiment, the inflated volume of the pouches is maintained by continuing to blow air into the pouch until substantially the entire length of the inflation opening  59  is sealed. In the example of  FIGS. 8A ,  8 B and  9 , the blower  60  blows air into a pouch being sealed up to a location that is a short distance D 1  from closing position where the sealing assembly  62  pinches the top and bottom layers  14 ,  16  to maintain the inflated volume of the pouches. This distance D 1  is minimized to minimize the volume of air that escapes from the inflated pouch before the trailing transverse seal of the inflated pouch reaches the closing position. For example, the distance D 1  may be 0.250 inches or less, to blow air into the inflation opening unit the trailing transverse seal is within 0.250 inches of the closing position. 
         [0042]    In the examples illustrated by  FIGS. 8A and 8B , the sealing assembly includes a pair of heated sealing elements  64 , a pair of cooling elements  66 , a pair of drive rollers  68 , and a pair of drive belts  70 . In an alternate embodiment, the pair of cooling elements is omitted. Each belt  70  is disposed around its respective heat sealing element  64 , cooling element  66  (if included), and drive roller  68 . Each belt  70  is driven by its respective drive roller  68 . The belts  70  are in close proximity or engage one another, such that the belts  70  pull the web  10  through the heat sealing elements  64  and the cooling elements  66 . The seal  42  is formed as the web  10  passes through first the heated sealing elements  64  and then a heat sink such as the cooling elements. One suitable heating element  64  includes heating wire  80  carried by an insulating block  82 . Resistance of the heating wire  80  causes the heating wire  80  to heat up when voltage is applied. The cooling elements  66  cool the seal  42  as the web  10  is pulled between the cooling elements. One suitable cooling element is an aluminum (or other heatsink material) block that transfers heat away from the seal  42 . Referring to  FIG. 9 , the spreading of the edges  38 ,  40  greatly reduces the stress imparted on the web material at or near the seal  42 . As a result, a much more reliable seal  42  is foamed. 
         [0043]      FIGS. 10-12  show another embodiment of a web  10 . In this embodiment, the spaced apart lines of perforations  26  extending from the inflation edge, as shown in  FIGS. 1-7B  and  9 , is replaced with a modified line of perforations  90 . As best seen in  FIG. 10 , a starting point  89  of the line of perforations  90  begins a distance D 2  from the inflation edge  18  and extends away from and generally perpendicular to the inflation edge  18 . As can be seen in  FIG. 10A , in an embodiment in which a frangible connection  21 ′ (also shown in  FIG. 2A ) is offset from the inflation edge  18  by a distance D 4 , the distance D 2  is greater than the distance D 4 . Hence, in the examples illustrated by  FIGS. 10-12 , the line of perforations  90  extends to a gap forming area  28  and an opposite edge line of perforations  24  extends to the opposite edge. In another embodiment, the gap forming area  28  is not included and the line of perforations  90  extends all the way or nearly all the way to the opposite edge. 
         [0044]    The distance D 2  is selected to prevent the cutter ( FIG. 12 ) from engaging the line of perforations in the exemplary embodiment. Although distance D 2  may vary based on the particular cutter implemented, in one embodiment, distance D 2  is approximately 0.25 to 0.375 inch in length.  FIG. 11  illustrates a row of inflated dunnage units. The elimination of perforations extending to the inflation edge  18  does not make it substantially harder to separate adjacent dunnage units in the row  11  of dunnage units  12 ′ in the exemplary embodiment. The dunnage units  12 ′ can still be separated by inserting an object or objects, such as a hand or hands, into the gap  13  and pulling one dunnage unit  12 ′ away from an adjacent dunnage unit  12 ′. When the dunnage units are pulled apart, the thin web of material between the starting point  89  and the inflation edge easily breaks. 
         [0045]    The process of forming perforations through the top and bottom layers of plastic  14 ,  16 , as the web  10  is formed, may cause the top and bottom layers  14 ,  16  to be adhere or be held together at the line of a perforations. When the lines of perforations extend all the way to the inflation edge and the cutter  58  cuts on one side of the inflation edge, the cutter will engage each line of perforations. Engagement of the lines of perforations by the cutter may cause the web to bind, wrinkle, bunch up, or gather around the edge of the cutter until the cutter passes the line of perforations and begins cutting the web again. In the embodiment illustrated by  FIGS. 10-12 , engagement of the line of perforations  90  with the cutter is eliminated by beginning the line of perforations  90  a distance D 2  away from the inflation edge  20 . As illustrated in  FIG. 12 , the tip of a cutter  58  utilized in opening the inflation edge  20  is positioned a distance D 3  past the inflation edge  20  as the edge is opened. The distance D 2  that the line of perforations  90  is away from the inflation edge  20  is configured to be greater that the distance D 3  to which the tip of a cutter  58  is positioned past the inflation edge  20 . As a result, the cutter  58  will not engage the lines of perforations. Likewise, in the case of the frangible connection  21 ′ shown in  10 A, the cutter  58  or blunt surface  58 ′ ( FIG. 7B ) that opens the offset frangible connection  21 ′ will not engage the lines of perforations  90 . This eliminates the possibility that the cutter or blunt surface could engage the lines of perforations and cause the web to bunch up or gather around the cutter  58  or blunt surface  58 ′ as the cutter  58  opens the inflation edge. 
         [0046]    The present invention is not to be considered limited to the precise construction disclosed. Various modifications, adaptations and uses may occur to those skilled in the art to which the invention relates. All such modifications, adaptations, and uses fall within the scope or spirit of the claims.