Abstract:
The present invention relates to improvements for the manufacturing of a wave-cut bag of polymeric film, more specifically a wave-cut bag with a body having improved shock, tear and puncture resistance. The polymeric film has an embossed pattern of a plurality of embossed regions that are comprised of a plurality of parallel, linear embosses. Further disclosed is a process for intermittently applying the embossed pattern to a collapsed tube of a blown film extrusion process. The collapsed tube with the intermittently applied embossed pattern is particularly well suited for constructing wave-cut trash bags with the embossed pattern applied to a central body of the wave-cut bags.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation-in-part of pending U.S. application Ser. No. 15/139,480, filed Apr. 27, 2016, which is a continuation-in-part of U.S. application Ser. No. 14/659,785, filed Mar. 17, 2015, now U.S. Pat. No. 9,487,334. This application is also a continuation-in-part of pending U.S. application Ser. No. 14/645,533, filed Mar. 12, 2015. All three of the aforementioned applications are hereby incorporated by reference into this disclosure. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to improvements in bags made from polymeric film and processes for manufacturing polymeric film bags. 
         [0004]    2. Description of the Related Art 
         [0005]    Polymeric films are used in a variety of applications. For example, polymeric films are used in sheet form for applications such as drop cloths, vapor barriers, and protective covers. Polymeric films can also be converted into plastic bags, which may be used in a myriad of applications. The present invention is particularly useful to trash bags constructed from polymeric film. 
         [0006]    Polymeric bags are ubiquitous in modern society and are available in countless combinations of varying capacities, thicknesses, dimensions, and colors. The bags are available for numerous applications including typical consumer applications such as long-term storage, food storage, and trash collection. Like many other consumer products, increased demand and new technology have driven innovations in polymeric bags improving the utility and performance of such bags. The present invention is an innovation of particular relevance to polymeric bags used for trash collection and more particular for larger bags used for the collection of larger debris, such as yard debris. 
         [0007]    Polymeric bags are manufactured from polymeric film produced using one of several manufacturing techniques well-known in the art. The two most common methods for manufacture of polymeric films are blown-film extrusion and cast-film extrusion. In blown-film extrusion, the resulting film is tubular while cast-film extrusion produces a generally planar film. The present invention is generally applicable to drawstring trash bags manufactured from a blown-film extrusion process resulting in tubular film stock. Manufacturing methods for the production of bags from a collapsed tube of material are shown in numerous prior art references including, but not limited to, U.S. Pat. Nos. 3,196,757 and 4,624,654, which are hereby incorporated by reference. 
         [0008]    In blown film extrusion, polymeric resin is fed into an extruder where an extrusion screw pushes the resin through the extruder. The extrusion screw compresses the resin, heating the resin into a molten state under high pressure. The molten, pressurized resin is fed through a blown film extrusion die having an annular opening. As the molten material is pushed into and through the extrusion die, a polymeric film tube emerges from the outlet of the extrusion die. 
         [0009]    The polymeric film tube is blown or expanded to a larger diameter by providing a volume of air within the interior of the polymeric film tube. The combination of the volume of air and the polymeric film tube is commonly referred to as a bubble between the extrusion die and a set of nip rollers. As the polymeric film tube cools travelling upward toward the nip rollers, the polymeric film tube solidifies from a molten state to a solid state after it expands to its final diameter and thickness. Once the polymeric film tube is completely solidified, it passes through the set of nip rollers and is collapsed into a collapsed polymeric tube, also referred to as a collapsed bubble. 
         [0010]    One common method of manufacturing trash bags involves segregating the collapsed polymeric tube into individual trash bags by forming seals which extend transversely across the entire width of the tube. Typically, a line of perforations is formed immediately adjacent and parallel to each seal to facilitate separation of the trash bags one from another. After the trash bags are sealed and perforated, the trash bags can be twice-folded axially into a fractional width configuration. 
         [0011]    It is also known to provide wave-cut trash bags. A wave-cut trash bag has a wave or lobe-shaped configuration at its open end. This provides two or more lobes, which can be used to tie the trash bag in a closed configuration after it is filled with refuse. 
         [0012]    Wave-cut trash bags can be manufactured by providing closely spaced, parallel transversely extending seals at predetermined intervals along the collapsed polymeric tube. A transversely extending line of perforations is provided between the closely spaced, parallel seals. The collapsed polymeric tube is then separated longitudinally along a wave or lobe-shaped line located equidistant between the edges of the tube. 
         [0013]    The lobe-shaped features, or lobes, of a wave-cut trash bags, which may also be referred to as tie-flaps, provide a convenient user feature to tie and close the opening of the bag. The lobes are grasped and knotted to seal the bag opening. Representatives of wave-cut or “tie bags” can be found in the following prior art of U.S. Pat. Nos. 4,890,736, 5,041,317, 5,246,110, 5,683,340, 5,611,627, 5,709,641, and 6,565,794, which are hereby incorporated by reference into this disclosure. 
         [0014]    In a further publication, U.S. Pat. Appl. Pub. 2008/0292222A1 discloses a bag having at least two “tie flaps” with gripping features embossed on at least one surface of the tie flaps. It is further disclosed that the bag may be formed from a tube of polymeric material. However, the publication further discloses that the gripping feature is formed in a linear fashion along a length of a blown film bubble that is then slit lengthwise in a wave pattern. The bubble is then formed into bags after being collapsed with a collapsed edge forming a bottom of the bag. 
         [0015]    It has been determined, however, that the lobes of prior art wave-cut bags are often difficult to grasp and manipulate, especially if the lobes are contaminated with slippery trash contamination such as oil or grease or moist organic contaminants. Furthermore, wave-cut bags are often manufactured with thicker film than other types of trash bags since they often are intended for use with larger and heavier debris, such as yard debris and debris from home improvement projects. These thicker films used on larger wave-cut bags can be as thick as 3 mils and make it challenging for a user to manipulate the lobes of a wave-cut bag into a knot. Hence, it would be desirable to provide a wave-cut bag that has easier to grasp lobes that are also thinner than the rest of the bag. The present invention represents a novel solution to address this need. 
         [0016]    It has also been determined that for certain thicknesses of wave-cut trash bags it may be desirable to provide a bag with thicker lobes relative to thinner a central body of the bag. Thicker lobes may provide a perception of strength to a user when handling the bag and provide a bag that forms a more robust closure. The thinner body of the bag allows a manufacturer to provide thicker lobes that are desired by consumers while also using less raw material than would otherwise be required to form a bag with a uniform thickness having the same thickness the area of the bag&#39;s lobes. 
         [0017]    Additional problems are understood to be inherent with the use of polymeric films in trash bags. For instance, the use of polymeric film presents technical challenges since polymeric film is inherently soft and flexible. Specifically, all polymeric films are susceptible to puncture and tear propagation. In some instances, it may be possible to increase the thickness of the film or select better polymers to enhance the physical properties of the film. However, these measures increase both the weight and cost of the polymeric film and may not be practicable. In light of the technical challenges of polymeric film, techniques and solutions have been developed to address the need for improved shock absorption to reduce the likelihood of puncture. For example, it is known to impart stretched areas into polymeric films as a means of inducing shock absorption properties into the film. 
         [0018]    U.S. Pat. No. 5,205,650, issued to Rasmussen and entitled Tubular Bag with Shock Absorber Band Tube for Making Such Bag, and Method for its Production, discloses using polymeric film material with stretchable zones wherein the film material has been stretched in a particular direction with adjacent un-stretched zones that extend in substantially the same direction. The combination of the stretched zones and adjacent un-stretched zones provides a shock absorber band intended to absorb energy when the bag is dropped. Specifically, when a bag is dropped or moved, the contents inside the bag exert additional forces that would otherwise puncture or penetrate the polymeric film. However, the shock absorber bands absorb some of the energy and may prevent puncture of the film. 
         [0019]    Another example of a polymeric film material designed to resist puncture is disclosed in U.S. Pat. No. 5,518,801, issued to Chappell and entitled Web Materials Exhibiting Elastic-Like Behavior. Chappell, in the aforementioned patent and other related patents, discloses using a plurality of ribs to provide stretchable areas in the film much like Rasmussen. Chappell also discloses methods of manufacturing such polymeric film with such ribs. 
         [0020]    Another example of shock absorption to prevent puncture is disclosed in U.S. Pat. No. 5,650,214 issued to Anderson and entitled Web Materials Exhibiting Elastic-Like Behavior and Soft Cloth-Like Texture. Anderson discloses using a plurality of embossed ribs defining diamond-shaped areas with a network of unembossed material between the diamond-shaped areas. Thus, the unembossed area comprises a network of straight, linear unembossed material extending in two perpendicular directions. 
         [0021]    The foregoing disclosures specifically address the desire to increase the shock absorption of polymeric film to reduce the likelihood of punctures occurring in the film. However, none of the foregoing disclosures address the problem of reducing tear propagation in the polymeric film of a bag. 
         [0022]    Previously known solutions to limiting tear propagation are based on two primary concepts. First, longer and more tortuous tear paths consume more energy as the tear propagates and can help in limiting the impact of the tear in a bag or polymeric film. Second, many polymeric films, particularly polymeric films made using a blown-film extrusion process, have different physical properties along different axes of the film. In particular, blown films are known to have higher tear strength in the cross-direction versus the corresponding tear strength in the machine direction. Certain prior art solutions take advantage of the differential properties of polymeric films by redirecting tears into a different direction. This redirecting of tears can offer greater resistance to a tear propagating. For example, some solutions redirect a tear propagating in the weaker machine direction of blown film into the stronger cross-direction. 
         [0023]    One solution for reducing tear propagation is based on the idea that longer, tortuous tear paths are preferable and is described in U.S. Pat. No. 6,824,856, issued to Jones and entitled Protective Packaging Sheet. Jones discloses materials suitable for packaging heavy loads by providing an embossed packaging sheet with improved mechanical properties. Specifically, a protective packaging sheet is disclosed where surfaces of the sheet material are provided with protuberances disposed therein with gaps between protuberances. The protuberances are arranged such that straight lines necessarily intersect one or more of the protuberances. The resulting protective packaging sheet provides mechanical properties where tears propagating across the polymeric sheet are subject to a tortuous path. The tortuous path is longer, and more complex, than a straight-line tear, and a tear propagating along such a path would require markedly more energy for continued propagation across the film compared to a tear along a similar non-tortuous path in the same direction. Thus, due to the increased energy required for tear propagation, the tortuous path ultimately reduces the impact of any tears that do propagate across the film. 
         [0024]    Another example of a tear resistant plastic film is disclosed in U.S. Pat. No. 8,357,440, issued to Hall and entitled Apparatus and Method for Enhanced Tear Resistance Plastic Sheets. Hall discloses an alternative tortuous path solution and further relies on the fact discussed above that certain polymer films, particularly polymeric films made in a blown-film extrusion process, are known to have a stronger resistance to tear in the cross direction when compared to the machine direction. 
         [0025]    Hall discloses a solution that contemplates using preferably shaped embosses, particularly convex shaped embosses with a curved outer boundary, to provide maximum resistance to tear propagation. In most polymeric films, a tear will have a tendency to propagate along the path of least resistance or in the machine direction. Hall contemplates redirecting propagating tears in a tortuous path with the additional intent of redirecting the machine direction tears along the curved edges of the embossed regions and into a cross direction orientation. The redirected tears in the cross direction will be subject to additional resistance and, preferably, will propagate to a lesser degree than a tear propagating in the machine direction in an unembossed film. 
         [0026]    U.S. Pat. No. 9,290,303 to Brad A. Cobler (the Cobler patent) with a filing date of Oct. 24, 2013, herein incorporated by reference into this disclosure, discloses use of an embossing pattern on polymeric film that balances both properties of shock absorption and tortuous tear paths in the cross direction, into a single, practicable polymeric film. The patent discloses that the embossing pattern comprises a plurality of embossed regions comprised of a plurality of parallel, linear embosses. The plurality of embossed regions is arranged so that a straight line cannot traverse the polymeric film without intersection at least one of the plurality of embossed regions. 
         [0027]    It would be desirable to provide the polymeric film of the body of wave-cut trash bags, or the body of trash bags in general, with the embossing pattern of the Cobler patent. A bag with this pattern would provide a trash bag with improved shock absorption and resistance to tear propagation in comparison to the state of the art wave-cut trash bags. It would also be desirable to provide a wave-cut bag with the Cobler embossing pattern only in the body of the bag and not in the bottom area of the bag or in the lobes of the wave-cut opening. The emboss pattern defined only in the body of the bag would provide the above-discussed advantages without the embossing pattern interfering with the tying of the bag with the lobes or interfering with the bottom seal of the bag. The present invention addresses these additional objectives. 
       SUMMARY OF THE PRESENT INVENTION 
       [0028]    In at least one embodiment of the present invention, a bag of polymeric film may be formed. To form the polymeric bag, a collapsed tube of polymeric film may be formed with a machine direction. The collapsed tube may be formed from a blown film extrusion process. Once the collapsed tube is formed, a pair of intermeshing rollers may intermittently engage the collapsed tube to form a plurality of embossed sections and unembossed sections in the collapsed tube. Each of the embossed sections may comprise a plurality of embossed regions and each of the embossed regions may be separated from adjacent embossed regions by an unembossed arrangement. 
         [0029]    Once the collapsed tube is embossed, a bag converting operation may form the collapsed tube into a plurality of bags. Each one of the plurality of bags may have at least a fraction of one of the plurality of embossed sections. Each of the embossed sections may extend across the entire width of the collapsed tube. The bag converting operation may further comprise forming sets of closely spaced, parallel seals extending transversely across the entire width of the collapsed tube. Each set of closely spaced parallel seals may be at equally spaced intervals from each other. The bag converting operation may also form perforation lines extending transversely across the entire width of the collapsed tube with a perforation line located between each set of closely spaced, parallel seals. A plurality of wave-shaped perforations may also be formed in the collapsed tube. A location of each wave-shaped perforation may be equidistant from adjacent perforation lines. Each wave-shaped perforation may be centered within one of the plurality of incrementally stretched sections. 
         [0030]    The converting operation may further comprise a timing operation. The timing operation may detect the location of each perforation line and generate a timing signal. The location of each wave-shaped perforation and embossed section may be based upon the timing signal. The timing operation may be a standalone operation or may be integrated into the bag converting operation. The timing signal may trigger the intermeshing rollers to engage and disengage the collapsed tube twice to form two embossed sections for each timing signal generated. 
         [0031]    The pair of intermeshing rollers of the embossing process may counter-rotate in relation to each other so that the collapsed tube is fed through the pair of intermeshing rollers. Each roller may have a rotational axis and the two axes of the rollers may be parallel with each other. The axes of each of the pair of intermeshing rollers may also be perpendicular to the machine direction of the collapsed tube. The pair of intermeshing rollers may comprise a first roller and a second roller. The first roller may include a plurality of grooves perpendicular to the axis of the first roller. The plurality of grooves on the first roller may intermesh with an embossing pattern on the second roller. Each intermeshing roller may rotate in a direction that the collapsed bubble is moving so that the bubble is drawn through the pair of intermeshing rollers. A pair of post-embossing rollers downstream from the pair of intermeshing rollers and a pair of pre-embossing rollers upstream of the intermeshing rollers may be provided to control the tension in the collapsed tube when it passes through the intermeshing rollers. 
         [0032]    In at least certain embodiments, the embossing pattern may comprise a plurality of embossment regions defined in the second roller and each embossment region may comprise a plurality of embossment ridges. Each of the plurality of embossment ridges may be linear and parallel to each other. Each embossment region may be defined by a continuous embossment boundary. The embossment boundary may be generally flat and comprise at least a plurality of first segments and a plurality of second segments. The plurality of first segments may extend in a first direction and the plurality of second segments may extend in a second direction. The first and second directions may be distinct from each other. The embossment boundary may further comprise a plurality of third segments extending in a third direction with the third direction distinct from the first and second directions. The embossment boundary may also be devoid of embossment ridges. 
         [0033]    In a further embodiment of the present invention, a bag is formed form a collapsed tube of polymeric film. The bag may comprise a first panel and a second panel. The first panel and the second panel may be joined along a first side edge, a second side edge, and a bottom edge by a bottom seal. The bottom seal may extend from the first side edge to the second side edge. The first side edge may be formed from a first edge of the collapsed tube and the second side edge may be formed from a second edge of the collapsed tube. The first panel may have a first top edge opposite the bottom edge and the second panel may have a second top edge opposite the bottom edge. The first top edge and second top edge may define an opening of the bag. A distal end of both the top edge and second top edge may have a wave-shaped profile and the wave-shaped profile may define a plurality of lobes. In at least one embodiment, an embossed section may be defined only below the plurality of lobes and the embossed section may comprise a plurality of embossed regions. Each of the embossed regions may be separated from adjacent embossed regions by an unembossed arrangement. The embossed section may extend from the first side edge to the second side edge. 
         [0034]    In an additional embodiment of the present invention, a bag is formed form a collapsed tube of polymeric film. The bag may comprise a first panel and a second panel. The first panel and the second panel may be joined along a first side edge, a second side edge, and a bottom seal proximate to a bottom edge. The first side edge may be formed from a first edge of the collapsed tube and the second side edge may be formed from a second edge of the collapsed tube. The first panel may have a first top edge opposite the bottom edge and the second panel may have a second top edge opposite the bottom edge. The first top edge and second top edge may define an opening of the bag. A distal end of both the top edge and second top edge may have a wave-shaped profile comprising a plurality of crests and troughs. 
         [0035]    The bag of the embodiment may further include an upper embossment boundary below the plurality of troughs of the wave-shaped profile. The upper embossment boundary may extend from the first side edge to the second side edge. A lower embossment boundary may be defined below the upper embossment boundary and above the bottom seal. The lower embossment boundary may extend from the first side edge to the second side edge. An embossed section may extend between the first side edge and the second side edge. The embossed section may also extend between the upper embossment boundary and the lower embossment boundary. The embossed section of the bag may comprise a plurality of embossed regions of embossments. Each embossed region may be separated from adjacent embossed regions by an unembossed arrangement. A first unembossed section may extend from the upper embossment boundary to the plurality of crests and from the first side edge to the second side edge. The first unembossed section may have a generally flat surface and be devoid of embossments. A second unembossed section may extend from the lower embossment boundary to the bottom edge and from the first side edge to the second side edge. The second unembossed section may have a generally flat surface and be devoid of embossments. 
         [0036]    In at least certain embodiments, the continuous unembossed arrangement may comprise at least a plurality of first segments and a plurality of second segments. The plurality of first segments may extend in a first direction and the plurality of second segments may extend in a second direction. The first and second directions may be distinct from each other. The first and second embossment boundaries may be generally linear and parallel to the bottom seal. A machine direction of the collapsed tube may extend in a direction generally perpendicular to the bottom seal. The bottom seal may be generally perpendicular to the first side edge and the second side edge. Each of the embossed regions may comprise linear ribs and each linear rib may be generally perpendicular to the first side edge and the second side edge. A first transition zone may be between the embossed section and the first unembossed section. The first transition zone may comprise a plurality of linear embossments. The plurality of linear embossments may have tapering heights with a height of the linear embossments decreasing as the linear embossments extend towards the first unembossed section. The embossed section may further be formed from a pair of intermeshing rollers. 
     
    
     
       BRIEF DESCRIPTION OF THE RELATED DRAWINGS 
         [0037]    A full and complete understanding of the present invention may be obtained by reference to the detailed description of the present invention and certain embodiments when viewed with reference to the accompanying drawings. The drawings can be briefly described as follows. 
           [0038]      FIG. 1  depicts a perspective view of a first embodiment of the present invention. 
           [0039]      FIG. 2 a    depicts a partial perspective view of the first embodiment of the present invention. 
           [0040]      FIG. 2 b    depicts a partial perspective view of an alternate second embodiment of the present invention. 
           [0041]      FIG. 3 a    depicts a perspective view of an incremental stretching operation of the first and second embodiments. 
           [0042]      FIG. 3 b    depicts a secondary perspective view of the incremental stretching operation of the first and second embodiments. 
           [0043]      FIG. 4 a    depicts a perspective view of an incremental stretching operation of a third embodiment of the present invention. 
           [0044]      FIG. 4 b    depicts a perspective view of an incremental stretching operation of a fourth embodiment of the present invention. 
           [0045]      FIG. 5  depicts a front view of a fifth embodiment of the present invention. 
           [0046]      FIG. 6  depicts another front view of the fifth embodiment of the present invention. 
           [0047]      FIG. 7  depicts a front view of a sixth embodiment of the present invention. 
           [0048]      FIG. 8  depicts another front view of the sixth embodiment of the present invention. 
           [0049]      FIG. 9  depicts a top planar view of an intermeshing roller of a seventh embodiment of the present invention. 
           [0050]      FIG. 10  depicts a front view of a trash bag of the seventh embodiment of the present invention. 
           [0051]      FIG. 11  depicts a side view of the gradual transition from an un-ribbed to a ribbed polymeric film due to an incremental stretching operation. 
           [0052]      FIG. 12  depicts a perspective view of an eighth embodiment of the present invention. 
           [0053]      FIG. 13  depicts a partial perspective view of the eighth embodiment of the present invention. 
           [0054]      FIG. 14  depicts a top view of an embossing pattern of the eighth embodiment. 
           [0055]      FIG. 15 a    depicts a perspective view of an incremental stretching operation of the eighth embodiment. 
           [0056]      FIG. 15 b    depicts a second perspective view of the incremental stretching operation of the eighth embodiment. 
           [0057]      FIG. 16  depicts a perspective planar or flattened view of a section of an embossing roller of the eighth embodiment. 
           [0058]      FIG. 17  depicts a front view of a ninth embodiment of the present invention. 
           [0059]      FIG. 18  depicts a front view of a tenth embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0060]    The present disclosure illustrates several embodiments of the present invention. It is not intended to provide an illustration or encompass all embodiments contemplated by the present invention. In view of the disclosure of the present invention contained herein, a person having ordinary skill in the art will recognize that innumerable modifications and insubstantial changes may be incorporated or otherwise included within the present invention without diverging from the spirit of the invention. Therefore, it is understood that the present invention is not limited to those embodiments disclosed herein. The appended claims are intended to more fully and accurately encompass the invention to the fullest extent possible, but it is fully appreciated that certain limitations on the use of particular terms are not intended to conclusively limit the scope of protection. 
         [0061]    Referring initially to  FIGS. 1 and 2 , a process for forming wave-cut trash bags with incrementally stretched tie flaps or lobes is shown. The trash bags may be formed by a blown film extrusion process. The blown film extrusion process begins by molten polymeric resin being extruded through an annular die of an extruder, or extrusion operation  102  to form a bubble or tube of molten polymeric film  104 . The direction that the film is extruded out of the die is commonly referred to as the machine direction (MD). The direction of extrusion may also be referred to as the lengthwise direction of the bubble or polymeric film tube  104 . Hence, the length of the polymeric tube  104  extends parallel with the machine direction. The direction transverse to the machine direction is commonly referred to as the cross direction (CD). The blown film extrusion process is well known in the art and is further explained in U.S. Pat. No. 7,753,666, which is hereby incorporated by reference. 
         [0062]    The polymeric resin used in the blown film extrusion process may vary. However, for forming polymeric bags, a polyethylene resin is commonly used. In the current state of the art for polymeric bags, a blend of various polyethylene polymers may be used. A polymer blend can have linear low-density polyethylene (LLDPE) as the primary component, but other polymers may be utilized including, but not limited to, other polyethylene resins such as high-density polyethylene (HDPE) or low-density polyethylene (LDPE). Typically, the primary component of the polymer blend, such as linear low-density polyethylene (LLDPE), will comprise at least 75% of the polymer blend. The remaining portion of the polymer blend may include additives including, but not limited to, coloring additives, anti-blocking agents, and/or odor control additives. The film utilized to form polymeric bags may also comprise multiple layers of blown film resin. The resultant multi-layer film may be formed by coextrusion, a lamination process, or other methods of forming a multi-layer film known in the art. In each layer, one or more of the above-discussed polymers may be used. 
         [0063]    As shown in  FIG. 1 , once the bubble  104 , or polymeric tube, of molten film solidifies, the bubble  104  is collapsed by a pair of nip rollers  108 , which results in a collapsed tube  110 . The collapsed tube  110  includes two opposing interconnected surfaces of film extending continuously in a lengthwise direction. This continuously extending surface of film may be referred to as a web. The nip rollers  108  are commonly elevated above the extruder  106  a considerable distance, since the molten bubble  104  is air-cooled and requires a relatively large vertical distance to cool and solidify before the bubble  104  is collapsed. 
         [0064]    As shown in  FIG. 2 a   , once collapsed, the collapsed tube  110  has a first edge  112  and second edge  114  defined in the opposing edges of the collapsed tube  110  extending the length of the collapsed tube  110 . The distance from the first edge  112  to the second edge  114  of the collapsed tube  110  can define a width of the collapsed bubble. Once the collapsed tube  110  returns from the cooling tower (not shown), the collapsed tube  110  can feed directly into an incremental stretching operation  120 ; hence the incremental stretching can be performed as an in-line process, synchronously, with the blown film extrusion. As shown in  FIG. 1  and more clearly in  FIG. 2 a   , the incremental stretching operation  120  can be configured to only intermittently stretch the collapsed tube  110 , leading to incrementally stretched partial lengths of the collapsed tube  110 . 
         [0065]    As shown in  FIGS. 3 a -4 b   , the incremental stretching operation  120  can include a pair of intermeshing rollers  122   a ,  122   b . The diameter and length of each intermeshing roller  122   a ,  122   b  are equal in a preferred embodiment but may vary. As best shown in  FIG. 3 a   , the collapsed tube  110  can enter a nip  124  defined by the pair of intermeshing rollers  122   a ,  122   b . The rotational axes  128   a ,  128   b  of each roller  122   a ,  122   b  can be parallel to each other and transverse to the machine direction (MD) of the collapsed tube  110 . Each of the rollers  122   a ,  122   b  can have a plurality of protruding ridges  126  parallel to the axis of each roller  128   a ,  128   b  that extend around the entire circumference of each roller  122   a ,  122   b  at a constant spacing. The protruding ridges  126  of the rollers  122   a ,  122   b  can be configured to intermesh like gears. As the collapsed tube  110  enters the nip of the intermeshing rollers  122   a ,  122   b , the film of the collapsed tube  110  is stretched based upon the depth and spacing of the grooves  126 . 
         [0066]    As best shown in  FIG. 3 a   , the film of the collapsed tube  110  is stretched by each groove of the plurality of protruding ridges  126  in the machine direction, which results in a pattern of stretched and un-stretched lengths with each length extending along the width or cross-direction of the collapsed tube  110 . Examined closely, this pattern of stretched and un-stretched lengths results in a pattern of parallel thick ribs (un-stretched lengths) and thin ribs (stretched lengths) extending in the cross-direction of the collapsed tube  110  for each incrementally stretched section  116 . 
         [0067]    The preferred actual size and spacing of each of the plurality of protruding ridges  126  in relation to each of the rollers  122   a ,  122   b  is substantially exaggerated for ease of illustration in the figures. In one preferred embodiment, the spacing of the grooves can be 20 grooves per inch about the circumference of each roller  122   a ,  122   b , with each groove leading to a matching thin rib/thick rib extending along the width of the collapsed tube  110 . The spacing of the ribs in the film after stretching is greater than the groove spacing of the intermeshing rollers  122   a ,  122   b , since the stretching causes the ribs to spread away from each other. The pattern of thick and thin ribs is represented by a pattern of parallel and adjacent lines in the figures. 
         [0068]    Once again examining  FIG. 3 a    and  FIG. 3 b   , the incremental stretching operation  120  can be configured to only engage, and hence only incrementally stretch, the collapsed tube  110  intermittently. This intermittent engagement of the collapsed tube  110  leads to lengths of un-stretched sections  118  and lengths of incrementally stretched sections  116 . As illustrated in  FIG. 3 b   , the intermittent engagement of the collapsed tube  110  can be accomplished by the pair of intermeshing rollers  122   a ,  122   b  moving away from each other a certain distance G allowing the collapsed tube  110  to move past the incremental stretching operation  120  without being stretched by the intermeshing rollers  122   a ,  122   b . The gap G, as shown in  FIG. 3 b   , must be large enough to allow the collapsed tube  110  to pass through the nip  124  without interference from the intermeshing rollers  122   a ,  122   b.    
         [0069]    Shown in  FIG. 4 a    is an alternative method of intermittently incrementally stretching the collapsed tube  110 . Unlike the previous embodiment of the incremental stretching operation  120  shown in  FIGS. 3 a  and 3 b   , the rotational axes  128   c ,  128   d  of the pair of intermeshing rollers  122   a ,  122   b  are mounted stationary in relation to each other. However, the protruding ridges  126   a ,  126   b  extend only partially around the circumference of each roller  122   a ,  122   b  rather than about the entire circumference. The locations of the protruding ridges  126   a ,  126   b  on each roller  122   a ,  122   b  are spaced appropriately so that the protruding ridges  126   a ,  126   b  intermesh when the pair of rollers  122   a ,  122   b  revolve. Thus, the collapsed tube  110  is incrementally stretched only when the protruding ridges  126   a ,  126   b  intermesh and engage the collapsed tube  110 . The geometry of each roller  122   a ,  122   b  can be configured so that the collapsed tube  110  is not in contact with either of the rollers  122   a ,  122   b  when not engaged with the protruding ridges  126   a ,  126   b . In the alternative, the diameter of each roller  122   a ,  122   b , can be configured such that the surface of one or more of the rollers  122   a ,  122   b  is in contact with the collapsed tube  110  while the protruding ridges  126   a ,  126   b  are not intermeshed. One or more of the rollers  122   a ,  122   b  in contact with the collapsed tube  110 , when the protruding ridges  126   a ,  126   b  are not engaging the collapsed tube  110 , may assist in maintaining the desired tension in the collapsed tube  110 . 
         [0070]    The rollers of  FIG. 4 a    may rotate at a speed so that a tangential speed of each roller  122   a ,  122   b  matches a linear speed of the collapsed tube  110  passing through the nip  124 . In the alternative, the tangential speed of the rollers  122   a ,  122   b  may only match the speed of the collapsed tube  110  when the collapsed tube  110  is engaged by the protruding ridges  126   a ,  126   b . When the protruding ridges  126   a ,  126   b  are not engaged, the rotational speed, and hence the tangential speed, of the pair of rollers  122   a ,  122   b  can be decreased. In this instance, the diameter of each roller  122   a ,  122   b  must be configured such that the collapsed tube  110  is not in contact with the rollers  122   a ,  122   b  when not engaged with the protruding ridges  126   a ,  126   b , since the linear speed of the collapsed tube  110  is typically constant. Decreasing the speed of the rollers  122   a ,  122   b  when not engaged with the web has the advantage of allowing smaller diameter rollers than would be required if the rollers rotated at a constant speed. 
         [0071]    In one particular example, the incremental stretching operation  120  may be configured such that each incrementally stretched section  116  of the collapsed tube  110  is 15 inches in length after being stretched and each un-stretched section  118  is 85 inches in length. For rollers that rotate at a constant speed, the intermeshing rollers can be configured to stretch the collapsed tube approximately 15 percent such that the protruding ridges would extend about the circumference of each roller approximately 13 inches, stretching a length of 13 inches of the collapsed tube  110 , which results in a length of 15 inches after being stretched. The remaining smooth circumference of 85 inches would then be devoid of the protruding ridges, which results in a total circumference of approximately 98 inches and a diameter of approximately 31.2 inches for each roller  122   a ,  122   b.    
         [0072]    Unlike rollers that rotate at a constant speed, rollers  122   a ,  122   b  configured to run at an oscillating speed could have a smaller circumference and hence a smaller overall size. For instance, when not engaged, the rollers  122   a ,  122   b  could rotate with an average tangential speed of 50 percent of the linear speed of the web. The speed of the rollers  122   a ,  122   b  would not step down instantly to 50 percent. Thus, the rollers  122   a ,  122   b  would first decelerate, then rotate at a speed of less than 50 percent, and then accelerate prior to engaging the collapsed tube  110  again. This arrangement would only require a smooth partial circumference of one-half the previous smooth circumference of approximately 42.5 inches and a 13-inch partial circumference having protruding ridges  126   a ,  126   b  for a total circumference of approximately 55.5 inches and a diameter of approximately 17.7 inches for each roller  122   a ,  122   b . It also foreseeable that the rollers could rotate at an average tangential speed of much less than 50 percent when not engaged with the collapsed tube, such as 25 percent. 
         [0073]    Decreasing the diameter and hence the overall size of the rollers  122   a ,  122   b  offers several advantages. First, the cost to produce the rollers is decreased with rollers of decreased size. In addition, with smaller rollers, the time to manufacture the rollers may also be reduced. Smaller rollers lead to lighter weight rollers, which can lead to a mounting system for the rollers to be proportionally smaller and less expensive to construct. Lighter rollers may also lead to smaller, less expensive motors for driving the rollers. The use of smaller drive motors may also lead to less energy consumption. 
         [0074]    As shown in  FIG. 4 a   , the axes  128   a ,  128   b  of the rollers  122   a ,  122   b  can be located relative to the collapsed tube  110  so that the collapsed tube  110  passes equidistant from both rollers  122   a ,  122   b . However, in an alternative embodiment shown in  FIG. 4 b   , the collapsed tube  110  can be located slightly further away from the bottom roller  122   b  so that protruding ridges  126  may extend completely about the entire circumference of the bottom roller  122   b . In such an embodiment, the collapsed tube  110  passes over the lower protruding ridges  126  when not engaged by the upper protruding ridges  126   a . When the collapsed tube  110  is engaged by the upper protruding ridges  126   a , the collapsed tube  110  is pushed down into the lower protruding ridges  126  by the upper protruding ridges  126   a.    
         [0075]    In an alternative embodiment, the above-described incremental stretching operation  120  can be performed on a single layer web of polymeric film. For instance, the collapsed tube  110  may be slit along the first edge  112  so that the tube is open along the first edge  112 . The collapsed tube may then be spread out so that the two opposing layers of the collapsed tube  110  lie in the same plane adjacent to each other. The single layer web may then be intermittently incrementally stretched as described above. Once the stretching is complete, the web may be folded so that the two layers of the collapsed tube  110  once again oppose each other. The two layers of film adjacent to the first edge  112  may then be sealed together so that the collapsed tube  100  may still be used to form wave-cut trash bags. Performing the incremental stretching on one layer of film may prevent undesired binding of the two layers of film. 
         [0076]    In another alternative embodiment, rather than the incremental stretching operation  120  performed in-line and synchronously, as described above, with the blown film extrusion  102 , the incremental stretching  120  can be performed off-line from the blown film extrusion. For instance, once the polymeric bubble  104  is collapsed by the nip rollers  108 , the collapsed tube  110  can be rolled onto a master roll. The master roll can then be placed at a lead end of the incremental stretching operation  110  and the collapsed tube can be unrolled from the master roll. The collapsed tube  110  can then be fed into the incremental stretching operation  120 . 
         [0077]    Returning now to  FIGS. 1 and 2 , once the incremental stretching is complete, the collapsed tube  110  can enter a bag converter  140 . The bag converter  140  can form sets of closely spaced, parallel seals  142 . The sets of closely spaced parallel seals  142  can extend transversely to the machine direction and across the entire width of the collapsed tube  110 . As shown in FIGS.  5  and  6 , one seal of each set  142  can define a bottom seal  142   a  for each bag  154   a . As shown in  FIG. 2 a   , between each set of the closely spaced parallel seals  142 , the bag converter  140  can form perforation lines  144 . The perforation lines  144  can extend transversely to the machine direction, the cross direction, and across the entire width of the collapsed tube  110 . Each perforation line  144  can define the bag bottom  144   a  (shown in  FIG. 5 ) and separation point of adjoining bags  154 . 
         [0078]    Once again examining  FIG. 2 a   , once the sets of closely spaced parallel seals  142  and perforation lines  144  are formed, the bag converter  140  can fold the collapsed tube  110  one or more times, with each fold extending along the length of the collapsed tube  110  and parallel to the machine direction. In at least one particular embodiment, the collapsed tube  110  can be folded twice such that a width of the folded collapsed tube  110   a  is one-fourth the width of the un-folded collapsed tube  110 . Once folded, a first folded edge  112   a  and second folded edge  114   a  can be defined in opposing edges of each bag  154 . 
         [0079]    Once the collapsed tube  110  is folded, it can proceed into a wave-cutter  150 . The wave-cutter  150 , which may also be referred to as a wave-cutting operation, creates wave-cuts  152 . Wave-cuts  152  are wave-shaped perforations, extending across the width of the folded collapsed tube  110   a . The wave-cuts  152  can perforate the folded collapsed tube  110   a  in the shape of a one-half sine wave extending across the width of the folded collapsed tube  110   a . In one particular embodiment, the peak-to-peak amplitude of the sine wave can be approximately 5 inches but may vary considerably. Due to the collapsed tube  110   a  being folded twice when each wave-cut  152  is made, when un-folded each wave-cut can have, in general, a shape of two full sine waves extending across the width of the collapsed tube  110 . 
         [0080]    The location of the wave-cut  152  in relation to the perforation line  144  can be controlled by a timing operation  160 . The timing operation  160  can detect the location of each perforation line  144 . The timing operation  160  can rely upon a laser beam, infrared light, a spark generator, or another form of an electromagnetic signal to detect each perforation line  144 . The detected location of each perforation line  144 , along with the fixed position of the timing operation  160  and the collapsed tube  110  traveling at a steady state, can be used to time the incremental stretching operation  120  and wave-cutting operation  150  so that each wave-cut  152  and incrementally stretched section  116  are placed at predetermined locations. The timing operation  160  may be a standalone operation or may be integrated into the bag converter  150 . 
         [0081]    In at least one preferred embodiment, each wave-cut  152  can be centered by the wave-cutter  150  about a height of an incrementally stretched section  116 , in relation to the machine direction. Thus, a distance from a bottom of a wave-cut  152  to a lower boundary of an incrementally stretched section  116 , the lower boundary separating an incrementally stretched section  116  from an un-stretched section  118 , can be equal to a distance from a top of the wave-cut  152  to an upper boundary of the incrementally stretched section  116 , the upper boundary opposite from the lower boundary. Each centered wave-cut  152  and incrementally stretched section  116  can be equidistant from adjacent perforation lines  144 . In this preferred embodiment, once the collapsed tube  110  is separated at wave-cuts  152  and perforation lines  144  to form bags  154   a , an approximate one-half length of an incrementally stretched section  116  is defined on each bag  154   a  (in relation to a mid-point or average of the waveform of the wave-cut  152 ). 
         [0082]    In a particular example of this embodiment, the perforation lines  144  can be 100 inches away from each other. Each incrementally stretched section  116  and wave-cut  152  can also be separated from adjacent incrementally stretched sections  116  and wave-cuts  152  by 100 inches. Since the sections  116  and wave-cuts  152  are aligned or centered, a mid-point of each section  116  and wave-cut  152  is located 50 inches away from adjacent perforation lines  144 . 
         [0083]    Once the collapsed tube is folded and the wave-cuts  152  are placed, the folded collapsed tube  110   a  may be separated at the perforation lines  144  and wave-cuts  152  into individual bags  154  with each bag having a height of approximately 50 inches. Each bag  154  may then be overlapped with an adjoining bag and rolled into a roll of bags as is known in the art. 
         [0084]    Shown in  FIG. 2 b    is alternative embodiment to the embodiment illustrated in  FIG. 2 a   . The bag conversion process shown in  FIG. 2 b    is similar to the processes described for  FIG. 2 a    except for the length and relative location of each incrementally stretched section. The incremental stretching operation  220  of  FIG. 2 b    is configured to stretch a greater length of collapsed tube  110  relative to the incrementally stretched section  116  of  FIG. 2 a   , resulting in incrementally stretched sections  216  and un-stretched sections  218 . After being incrementally stretched, bag converter  240  can form sets of closely spaced parallel seals  242  centered about a height of an un-stretched section  218  and perforation lines  244  centered within each set of closely spaced seals  242 . 
         [0085]    Further shown in  FIG. 2 b    is wave-cutter  250  configured to place each wave-cut  252  centered about a height of another un-stretched section  218  resulting in individual bags  254  with a top open edge defined by wave-cut  252  and bottom seal  244 . An incrementally stretched section  216  is located in a central body and a first un-stretched section is located below the stretched body and a second un-stretched section is located above the stretched body. Other details of the bag conversion processes of  FIG. 2 b    are not explained further since it is duplicative with the processes as explained above for  FIG. 2   a.    
         [0086]    As one skilled in the may ascertain, the length of each incrementally stretched section  216  is greater than the incrementally stretched section  116  of  FIG. 2 a   . For instance, rather than a stretched length of 15 inches as described for  FIG. 2 a   , the incremental stretching process  220  may be configured to stretch the collapsed tube  210  approximately 30 inches when configured for manufacturing bags with a total height of 50 inches. This height could vary, however, depending upon the size of bag being manufactured and the desired length of the stretched body of the bag. The stretched body of the bag may centered between the bottom and top of the bag or it may be offset to a degree towards the bottom or top of the bag. For similar sized bags as described for  FIG. 2 a   , the other dimensions discussed above would remain unchanged. However, the size of the rollers necessary for the incremental stretching operation discussed above would change proportionally to accomplish the increased length of the incrementally stretched section. 
         [0087]      FIGS. 5 and 6  show in detail the structure of the trash bags  154  that may be formed from the above-described processes of  FIGS. 1, 2, and 3   a - 4   b .  FIG. 5  shows that once adjacent perforation lines  144  are separated, a matching pair of interconnected trash bags  154  are defined. A boundary of each trash bag is defined by one of the wave-cuts  152 . An incrementally stretched section  116  is shown located on the two adjoining bags  154 . Further shown is first edge  112  and second edge  114  of the collapsed tube  110  defining two opposing sides of the two adjoining bags  154 . Two opposing perforation lines  144  are shown defining a bottom of each adjoining bag  154 . Once the perforated wave-cut  152  is separated, two separate trash bags result. One of the resultant trash bags  154   a  is shown in  FIG. 6 . 
         [0088]    As shown in  FIG. 6 , each wave-cut trash bag  154   a  can comprise a front panel and a rear panel formed from opposing sides of the collapsed tube  110 . The trash bag  154   a  can have a first side edge  112   b  defined by the first edge  112  of the collapse tube  110  and a second side edge  114   b  defined by the second edge  114  of the collapsed tube  110 . The trash bag  154  can further have a bottom seal  142   a  defined by one seal of the closely spaced sets of seals  142 . A bag bottom  144   a  can be defined by one of the perforation lines  144 . The bag top  152   a  can be defined by one of the wave-cuts  152 . The bag top  152   a  can have a wave-cut profile. The bag top  152   a  can be defined on both the front panel and back panel of the bag  154   a  and the bag top  152   a  can define a bag opening. 
         [0089]    As shown in  FIGS. 2, 5 and 6 , an incrementally stretched portion  158  of the trash bag  154   a  can be comprised of an incrementally stretched section  116  of the collapsed tube  110 . The incrementally stretched portion  158  can be a fractional length of one of the incrementally stretched sections  116 . Within the incrementally stretched portion  158 , a plurality of lobes  156  can be defined. The plurality of lobes  156  may also be referred to as tie-flaps. A wave-cut profile height H can be defined as a vertical distance from a top of the wave-cut profile to a bottom of the wave-cut profile, the wave-cut profile height H equal to an peak-to-peak amplitude of the wave shape of the wave-cut profile. The incrementally stretched portion  158  can extend from the bag top  152   a  to at least the bottom of the wave-cut profile. However, at least in one embodiment, the incrementally stretched portion  158  can extend below the bottom of the wave-cut profile up to one-half the wave-cut profile height H. In an alternative embodiment, the incrementally stretched portion  158  can extend below the bottom of the wave-cut profile at least a distance equal to the wave-cut profile height H. The incrementally stretched portion  158  can define a plurality of ribs extending from the first side edge  112   b  to the second side edge  114   b  of the bag  154   a . The plurality of ribs can generally be parallel to each other and transverse to both the first side edge  112   b  and second side edge  114   b.    
         [0090]    In one particular example of the wave-cut trash bag  154   a , a height of the bag from the bag bottom  144   a  to the upper extent of the bag top  152   a  may be 50 inches. A width of the bag from the first side edge  112   b  to the second side edge  114   b  may be approximately 33 inches. The wave-cut profile height H may be 5 inches with the incrementally stretched portion  158  extending 2.5 inches below the bottom of the wave-cut profile. Thus, the incrementally stretched portion  158  may have a height of approximately 7.5 inches, resulting in the remaining 42.5 inches of bag height un-stretched. The incrementally stretched portion  158  may be stretched approximately 15%. Thus, if the film of the collapsed tube is formed with a thickness of 3 mil, the incrementally stretched portion  158  may have an average thickness of approximately 2.5 mil with the remaining portions of the bag having a thickness of 3 mil. 
         [0091]    Shown in  FIGS. 7 and 8  is an alternative embodiment of the invention formed by the processes detailed by  FIG. 2 b    as described above. Rather than each incrementally stretched section  116  aligned with one of the wave-cuts  152 , each incrementally stretched section  116  can be offset from each wave-cut  152 , as explained for  FIG. 2 b    above. In this embodiment, each incrementally stretched section  116  is between adjacent perforation lines  140  and wave-cuts  152  so that a bag body  160  of each resultant bag  154  is incrementally stretched. The bag body  160  can be located between the lower extent of the bag top  152   a  and the bag bottom  144   a.    
         [0092]    Further shown in  FIG. 8  are incrementally stretched transition zones  160   a  and  160   b . It has been determined that when a polymeric web undergoes an incremental stretching operation as discussed above, the film of the web undergoes a transition from un-stretched film to fully incrementally stretched film. This transition is represented by the transitions zones  160   a  and  160   b  shown in  FIG. 8 . The structure of these transition zones is further detailed below in the discussion of  FIG. 11 . 
         [0093]    In one particular example of the embodiment shown in  FIGS. 7 and 8 , the intermeshing rollers  122   a ,  122   b  can engage the collapsed tube  110  approximately 2.5 inches away from each side of each perforation line  142 . Each incrementally stretched section  116  can be approximately 40 inches long, which results in a length of approximately 7.5 inches of un-stretched film from the upper extent of the bag top  152   a  to a top of the incrementally stretched bag body  160  for a bag having a total length of 50 inches. The bag body  160  can be stretched approximately 17 percent so that an initial film thickness of 3 mil is stretched to approximately 2.5 mil within the bag body  160 . This embodiment allows less film, and hence less polymeric material, to be used than an otherwise similar un-stretched bag. 
         [0094]    It is foreseeable, however, that the bag may disclosed in  FIGS. 7 and 8  be shorter in length, such as 33 inches in length, since it is contemplated that bag  154   a  with an incrementally stretched body would be desirable for thinner wave-cut bags between 1-2 mils than the heavier 3 mil thick bags. Nonetheless, for bags in shorter lengths, such as 33 inches, it is contemplated that the other above discussed dimensions would be proportional to the dimensions discussed above for a bag having a length of 50 inches. It is further contemplated that a desirable thickness of bag  154   a , as illustrated by  FIG. 8 , with a length of 33 inches may be approximately 1.3 mils. In at least one embodiment, it may be desirable to stretch central body of such a bag approximately 20% that results in the gauge by weight of the bag body being approximately one mils. 
         [0095]    The embodiment shown in  FIGS. 7 and 8  may also be implemented on a wave-cut trash bag having typical dimensions of a kitchen trash bag with. The bag body  160  can be stretched approximately 16 percent so that an initial film thickness of 0.7 mil is stretched to approximately 0.6 mil within the bag body  160 . 
         [0096]      FIG. 9  illustrates yet another embodiment of the incremental stretching operation. Shown in  FIG. 9  is a top planar view of an alternate embodiment of the outer surface of upper intermeshing roller  122   a . The closely spaced parallel lines of  FIG. 9  represent edges of each protruding ridge  126   a . Although not to the same extend as previous illustrations, the spacing between adjacent ridges is exaggerated for ease of illustration. For reference, shown in dashed lines is the outline of the intended corresponding placement of a wave-cut  152 . Within the plurality of protruding ridges  126   a  is shown a plurality of ridge voids  132 . Each ridge void  132  is a location from which a length of protruding ridges has been removed from the intermeshing roller  122   a . Each ridge void  132  defines a location where the intermeshing roller  122   a  will fail to stretch the collapsed tube  110  within each incrementally stretched section  116 . The ridge voids  132  are located about the intermeshing roller  122   a  such that an upper region of each lobe  156  of each bag  154  is left un-stretched. 
         [0097]      FIG. 10  illustrates the structure of bag  154   a  formed by the alternate embodiment of the incremental stretching operation as illustrated by  FIG. 9 . As a result of the plurality of ridge voids  132 , defined in an upper region of each lobe  156  is an un-stretched tip  132   a  that is devoid of any ribs that otherwise would have been formed by the incremental stretching operation. As shown in  FIG. 10 , a plurality of un-stretched tips  132  is defined on the bag  154 . In a likewise manner, the incrementally stretched portion  158  of the bag does not extend to the upper extent of the bag top  152   a . The remaining features of bag  154   a  remain unchanged from the embodiment illustrated in  FIGS. 5 and 6 . The un-stretched tips  132   a  may further improve the ease of tying the wave-cut trash bag versus the previously described embodiments. 
         [0098]    Shown in  FIG. 11  is a side view of a partial length of film, with the thickness of the film exaggerated for clarity, subjected to an intermittent incremental stretching process as discussed above. Prior to entering an incremental stretching operation, such as operation  120  shown in  FIG. 2 a   , the height, or thickness of the web  170 , e.g. collapsed tube  110 , is initially a first height H 1  as shown in  FIG. 11 . The first height H 1  is approximately equivalent to the gauge of the web. The incremental stretching operation forms thick ribs  172  and thin ribs  174  into the web  170 . When the stretching operation initially engages the web  170 , an initial height of the cross section of the web is a second height H 2 , a first transition height, since the stretching operation requires a certain amount of web length to fully engage the web  170 . Multiple additional thin ribs of decreasing transition height (not shown) can be formed as the incremental stretching operation further engages the web  170 . Once the stretching operation reaches a steady state operation, the height of each thin rib  174  decreases to a constant third height H 3  that is maintained until the incremental stretching operation begins to disengage the web  170 . The length of the web encompassing the thin ribs having heights between H 1  and H 3  can be defined as a first transition zone. 
         [0099]    Although not shown in  FIG. 11 , when the incremental stretching operation begins to disengage the web  170 , the transition reverses with a certain amount of thin ribs  174  having varying increasing heights, transitioning from the third height H 3  until reaching the first height H 1  once the incremental stretching operation fully disengages web  170 . The length of web that encompasses the thin ribs with increasing heights between H 3  and H 1  can be defined as a second transition zone. This cycle of transition zones repeats when the incremental stretching operation is engaged once again for the next section of incrementally stretched film. 
         [0100]    Shown in  FIGS. 12-16  is a further embodiment of the present invention. Rather than incrementally stretching the bags, the process of  FIGS. 12-16  intermittently embosses a pattern onto the collapsed tube  110 . The embossed pattern allows the collapsed tube  110  to expand in the cross-direction to absorb shock in the cross-direction. Certain features of collapsed tube  110  remain unchanged from the previously discussed embodiment. These features share the same reference numbers and the disclosure above may be referenced for explanation of these shared features. 
         [0101]    The embossing pattern utilized on the collapsed tube as shown in  FIGS. 12-16  allows bags manufactured from the disclosed process to expand in the cross-direction, in the width direction of the bags, from a first side edge to a second side edge of the bag, to increase the capacity of the bags when filled with debris. The embossing pattern further prevents the propagation of tears due to the tortuous path defined by the embossed pattern since a straight line cannot pass through more than one embossed region without intersecting an adjacent embossed region. 
         [0102]    Shown in  FIG. 14  is a detailed schematic view of a certain embodiment of the embossed pattern as illustrated generally in  FIGS. 12 and 13 . The embossed pattern  600  has a plurality of embossed regions  610 , each embossed region  610  having a generally hexagonal shape with each embossed region  610  separated by a continuous unembossed arrangement  620 . One of the hexagonal shapes is indicated by dashed lines A in  FIG. 14 . The dashed lines of A are shown for reference only and form no structure of the disclosed invention. Each embossed region  610  is shown as defined by nine parallel and adjacent linear embosses  630 . The two opposing horizontally extending sides of each embossed region  610  is defined by three middle adjacent parallel linear embosses  630  with equal length; each horizontal side of the hexagon formed by adjacent ends of the three linear embosses  630 . Each of the other four diagonal sides of the hexagon can be defined by an endpoint of an outer emboss of the three middle adjacent linear embosses  630  and adjacent end points of three other outer adjacent linear embosses  630 . Each of the three other adjacent linear embosses  630  can decrease in length the same amount as the adjacent linear emboss  630 . 
         [0103]    The hexagonal shaped embossed regions  610  of  FIG. 14  can be oriented such that opposing vertices of each hexagon are at a left and right side of each hexagon is illustrated in  FIG. 14 . Adjacent to the vertices can be two short opposing, linear embosses  630  at each end of each embossed region  610 . These opposing vertices encourage each embossed region to fold-in when the linear embosses unfold in the horizontal direction. Hence, a film with the embossed pattern  600  of  FIG. 14  expands in the horizontal direction but not in vertical direction. This expansion is much greater and at a much lower force than would be required to stretch the unembossed film. 
         [0104]    With the embossed pattern applied to the collapsed tube  110  with the linear embosses  630  extending in the machine direction and the opposing vertices aligned in the cross-direction, the embossed pattern  600  as shown in  FIGS. 12, 13, 15   a , and  15   b  allows the polymeric film of the collapsed tube  110  to expand in the cross-direction of the collapsed tube  110 . Due to the hexagonal shape of the embossed regions  610 , the depicted embodiment of the embossed pattern  600  provides features to prevent tear propagation since a tear propagating in the cross direction will be interrupted by an embossed region  610 . 
         [0105]      FIG. 14  depicts the unembossed arrangement  620  having a plurality of first segments  620   a , a plurality of second segments  620   b , and a plurality of third segments  620   c . Each embossed region  610  is bounded by two first segments  620   a , two second segments  620   b , and two third segments  620   c . Each first segment  620   a  extends in a first direction that is generally horizontal. Each second segment  620   b  extends in a second direction that is oblique to the first direction. Each third segment  620   c  extends in a third direction that is oblique to both the first direction and the second direction. The first, second, and third directions are all distinct from each other. As shown in  FIG. 14 , each of the segments  620   a ,  620   b , or  620   c  are interrupted by an adjacent embossed region  610 , failing to extend past more than one embossed region  610 . 
         [0106]    As further shown in  FIG. 14 , the first segments  620   a  intersect both the second segments  620   b  and third segments  620   c . Furthermore, a first segment  620   a , a second segment  620   b , and a third segment  620   c  all intersect each other adjacent to both the upper and lower vertices of each embossed region  610 . In a particular embodiment of the embossed pattern  600 , the angle formed by each intersection by a first segment  620   a  with a second segment  620   b  or third segment  620   c  can be approximately 54 degrees or the supplementary angle of 126 degrees. In the same embodiment, the angle formed by each intersection of a second segment  620   b  with a third segment  620   c  can be approximately 108 degrees. 
         [0107]    The preferred actual size and spacing of the embossed pattern  600  is substantially exaggerated for ease of illustration in the figures. However, in one preferred embodiment, the spacing of the ridges can be about 20 ridges per inch about the circumference of the first roller  322   a  so that each embossed region  610  is about 0.45 0.5 inch in length. 
         [0108]    Now returning to the bag formation process of  FIGS. 12 and 13 , the collapsed tube  110  can feed directly into embossing operation  320  once the film exits the nip rollers  108  of the extrusion operation  102 , as previously discussed in regards to  FIGS. 1 and 2   a . Thus, the embossing can be performed as an in-line process, synchronously, with the blown film extrusion. As shown in the figures, the embossing operation  320  can be configured to only intermittently emboss the collapsed tube  110 , leading to embossed partial lengths of the collapsed tube  110 . These embossed partial lengths of the collapsed tube can define a plurality of embossed sections  316  and unembossed sections  318  in the collapsed tube  110  as shown in  FIGS. 12 and 13 . 
         [0109]    As best shown in  FIGS. 15 a  and 15 b   , the embossing operation  320  can include a pair of intermeshing rollers  322   a ,  322   b . The diameter and length of the first intermeshing roller  322   a  and the second intermeshing roller  322   b  can be equal in at least certain embodiments. As further shown in  FIG. 15 a   , the collapsed tube  110  can enter nip  124  defined by the pair of intermeshing rollers  322   a ,  322   b . The rotational axes  328   a ,  328   b  of each roller  322   a ,  322   b  can be parallel to each other and transverse to the machine direction (MD) of the collapsed tube  110  as shown in the figures. 
         [0110]    As illustrated by  FIGS. 15 a  and 15 b   , the first intermeshing roller  322   a  can have a plurality of concentric ring-shaped ridges  326  and corresponding grooves extending about the circumference of the first roller  322   a . The ridges  326  can be evenly dispersed about the length of the roller  322   a . As explained further below, the second roller  322   b  can have an embossing pattern defined about its surface. The concentric ridges  326  of the first roller are constructed to intermesh with the embossing pattern of the second roller  322   b . With the embossing pattern defined on the second roller  322   b , as the collapsed tube  110  enters the nip of the intermeshing rollers  322   a ,  322   b , the film of the collapsed tube  110  is embossed with the embossing pattern  600 . 
         [0111]    Shown in  FIG. 16  is a detailed planar or flattened view of a section of the circumferential surface of the second intermeshing roller  322   b . The orientation of the embossing pattern  500  is oriented approximately 90 degrees from its orientation as illustrated in  FIGS. 15 a  and 15 b    for ease of illustration. As shown in  FIG. 16 , the embossing pattern  500  can have a plurality of embossment regions  510 . The hexagonal shape of one of the embossment regions  510  is indicated by dashed lines B in  FIG. 16 , which is shown for reference only and forms no structure of the disclosed invention. As further shown in  FIG. 16 , each embossment region  510  can comprise a plurality of embossment ridges  512 . Each of the embossment ridges can be parallel to each other and generally spaced evenly from each other. 
         [0112]    As further shown in  FIG. 16 , each of the embossment regions can be bounded by a continuous embossment boundary  520 . The embossment boundary can be substantially flat in relation to the embossment ridges  512  and devoid of any embossment ridges. The embossment boundary  520  can comprise first segments  520   a , second segments  520   b , and third segments  520   c . As shown in  FIG. 16 , each of the three segments can extend in a different direction from each other. As should be apparent to one of ordinary skill in the art, the surface of the section illustrated in  FIG. 16  necessarily follows the curvature of the surface of second roller  322   b  but is shown without the curvature (planar) for ease of illustration. The features of the embossing pattern  500  correspond with the emboss pattern  600  of  FIG. 14 .  FIG. 16  is provided to illustrate the pattern on intermeshing roller  322   b  which results in forming the emboss pattern  600  on collapsed tube  110  due to the embossing operation  320 . 
         [0113]    Now returning to  FIGS. 15 a  and 15 b   , the embossment ridges  512  (not shown) of the second intermeshing roller  322   b , which follow the curvature of roller  322   b , are offset from the concentric ridges  326  of the first roller  322   a  so that the ridges of the two rollers intermesh. As illustrated in  FIG. 15 a   , once the collapsed tube  110  passes through the two intermeshed rollers  322   a  and  322   b , the embossed pattern  600 , as illustrated by  FIG. 14 , is formed into the polymeric film of the collapsed tube  110 . 
         [0114]    As best shown in  FIGS. 12 and 13 , the film of the collapsed tube  110  is embossed with the embossed pattern  600  intermittently, due to intermittent engagement of the intermeshing rollers  322   a  and  322   b , as the collapsed tube  110  travels in the machine direction. This intermittent embossing results in a pattern of embossed and unembossed sections  316  and  318  on the collapsed tube  110 . As illustrated in  FIGS. 15 a  and 15 b   , the intermittent engagement of the collapsed tube  110  can be accomplished by the axes  328   a  and  328   b  of the pair of intermeshing rollers  322   a ,  322   b  moving away from each other a certain distance to create a gap G between the surface of the two rollers. This gap G allows the collapsed tube  110  to move past the embossing operation  320  without being embossed by the intermeshing rollers  322   a ,  322   b . The gap G, as shown in  FIG. 15 b   , must be large enough to allow the collapsed tube  110  to pass through the nip  124  without interference from the intermeshing rollers  322   a ,  322   b.    
         [0115]    Examining the  FIGS. 15 a  and 15 b    in detail illustrates the intermittent engagement and disengagement of the intermeshing rollers  322   a ,  322   b  that define the embossed and unembossed sections  316  and  318  in the collapsed tube  110 .  FIG. 15 a    shows the two intermeshing rollers  322   a ,  322   b  intermeshed with each other, with no gap, engaging the film of the collapsed tube  110  and forming an embossed section  316  as the collapsed tube  110  travels in the machine direction.  FIG. 15 b    shows the two intermeshing rollers  322   a ,  322   b  with the gap G between the rollers, not engaged, and hence no embossing taking place to define an unembossed section  318  on the film of the collapsed tube  110  as the tube continues to travel in the machine direction past the two intermeshing rollers  322   a ,  322   b.    
         [0116]    In an alternative embodiment, the above-described embossing operation  320  can be performed on a single layer web of polymeric film. For instance, the collapsed tube  110  may be slit along the first edge  112  so that the tube is open along the first edge  112 . The collapsed tube may then be spread out so that the two opposing layers of the collapsed tube  110  lie in the same plane adjacent to each other. The single layer web may then be intermittently embossed as described above. Once the embossing is complete, the web may be folded so that the two layers of the collapsed tube  110  once again oppose each other. The two layers of film adjacent to the first edge  112  may then be sealed together so that the collapsed tube  110  may still be used to form wave-cut trash bags. Performing the embossing on one layer of film may prevent undesired binding of the two layers of film. 
         [0117]    In another alternative embodiment, rather than the embossing operation  320  performed in-line and synchronously, as described above, with the blown film extrusion  102 , the embossing  320  can be performed off-line from the blown film extrusion. For instance, once the polymeric bubble  104  is collapsed by the nip rollers  108 , the collapsed tube  110  can be rolled onto a master roll. The master roll can then be placed at a lead end of the embossing operation  110  and the collapsed tube can be unrolled from the master roll. The collapsed tube  110  can then be fed into the embossing operation  320 . 
         [0118]    Returning now to  FIGS. 12 and 13 , it may be desirable to provide nip rollers on both sides of the embossing operation  320  to control tension in the collapsed tube as it enters and exits the intermeshing rollers  322   a  and  322   b  of the embossing operation  320 .  FIGS. 12 and 13  shows a pair of pre-embossing rollers  380  controlling tension in the collapsed tube prior to the film&#39;s entry into the nip of the intermeshing rollers of the embossing operation  320 , or upstream to the embossing operation  320 . The figures further show a pair of post-embossing rollers  382  controlling tension in the collapsed tube  110  upon exiting the intermeshing rollers of the embossing operation  320 , or downstream from the embossing operation  320 . Both the pre and post embossing rollers  380  and  382  are typical nip rollers as known in the art. The rotational speed of the pre and post embossing rollers  380  and  382  may be controlled independently from each other and from the intermeshing rollers  322   a  and  322   b  so that the tension in the collapsed tube  110  may be adequately controlled to aid in the desired engagement of the intermeshing rollers  322   a  and  322   b  into the polymeric film of the collapsed tube  110 . 
         [0119]    As further shown by  FIGS. 12 and 13 , once the embossing is completed by embossing operation  320 , the collapsed tube  110  can enter a bag converter  140 . The bag converter  140  can form sets of closely spaced, parallel seals  142 . The sets of closely spaced parallel seals  142  can extend transverse to the machine direction and across the entire width of the collapsed tube  110 . As shown in  FIGS. 17 and 18 , one seal of each set  142  can define a bottom seal  142   a  for each bag  354   a . As shown in  FIG. 13 , between each set of the closely spaced parallel seals  142 , the bag converter  140  can form perforation lines  144 . The perforation lines  144  can extend transversely to the machine direction, the cross direction, and across the entire width of the collapsed tube  110 . Each perforation line  144  can define the bag bottom  144   a  (shown in  FIG. 17 ) and separation point of adjoining bags  354 . 
         [0120]    Once again examining  FIG. 13 , once the sets of closely spaced parallel seals  142  and perforation lines  144  are formed, the bag converter  140  can fold the collapsed tube  110  one or more times, with each fold extending along the length of the collapsed tube  110  and parallel to the machine direction. In at least one particular embodiment, the collapsed tube  110  can be folded twice such that a width of the folded collapsed tube  110   a  is one-fourth the width of the un-folded collapsed tube  110 . Once folded, a first folded edge  112   a  and second folded edge  114   a  can be defined in opposing edges of each bag  354 . 
         [0121]    Once the collapsed tube  110  is folded, it can proceed into a wave-cutter  150 . The wave-cutter  150 , which may also be referred to as a wave-cutting operation, creates wave-cuts  152 . Wave-cuts  152  are wave-shaped perforations, extending across the width of the folded collapsed tube  110   a . The wave-cuts  152  can perforate the folded collapsed tube  110   a  in the shape of a one-half sine wave extending across the width of the folded collapsed tube  110   a . In one particular embodiment, the peak-to-peak amplitude of the sine wave can be approximately 5 inches but may vary considerably. Due to the collapsed tube  110   a  being folded twice when each wave-cut  152  is made, when un-folded each wave-cut can have, in general, a shape of two full sine waves extending across the width of the collapsed tube  110 . 
         [0122]    Once the collapsed tube is folded and the wave-cuts  152  are placed, the folded collapsed tube  110   a  may be separated at the perforation lines  144  and wave-cuts  152  into individual bags  354  with each bag having a height of approximately 50 inches in certain embodiments. Each bag  354  may then be overlapped with an adjoining bag and rolled into a roll of bags as is known in the art. 
         [0123]    The location of the wave-cut  152  in relation to the perforation line  144  can be controlled by a timing operation  160 . The timing operation  160  can detect the location of each perforation line  144 . The timing operation  160  can rely upon a laser beam, infrared light, a spark generator, or another form of an electromagnetic signal to detect each perforation line  144 . The detected location of each perforation line  144 , along with the fixed position of the timing operation  160  and the collapsed tube  110  traveling at a steady state, can be used to time the embossing operation  320  and wave-cutting operation  150  so that each wave-cut  152  and embossed section  316  are placed at predetermined locations. The timing operation  160  may be a standalone operation or may be integrated into the bag converter  150 . In an alternative embodiment, the timing of the embossing operation  320  may utilize the timing of the perforation operation itself rather than detection of the perforation line  144  to synchronize the engagement of the embossing operation  320  while the engagement of the wave-cutting operation may be based on an independent detection of the perforation line  144 . 
         [0124]    As shown in  FIGS. 12 and 13 , for each perforation line  144  placed in collapsed tube  110  two embossed sections  316  can be placed into the collapsed tube  110 . Thus, the timing operation  160  may be configured to engage the embossing operation  320  two times for each perforation line  144  formed or detected in the collapsed tube  110 . 
         [0125]    Now turning to  FIGS. 17 and 18 , the structure of the trash bags  354  formed from the above-described processes of  FIGS. 12-16  is shown.  FIG. 17  illustrates that once adjacent perforation lines  144  are separated, a matching pair of interconnected trash bags  354  are defined. A boundary of each trash bag is defined by one of the wave-cuts  152 . An embossed section  316  is shown located on each of the two adjoining bags  354 . Further shown is first edge  112  and second edge  114  of the collapsed tube  110  defining two opposing sides of the two adjoining bags  354 . Two opposing perforation lines  144  are shown defining a bottom of each adjoining bag  354 . Once the perforated wave-cut  152  is separated, two separate trash bags result. One of the resultant trash bags  354   a  is shown in  FIG. 18 . As may be apparent to one having ordinary skill the art, that due to folding operation  140  as shown in  FIGS. 12 and 13 , the pair of bags  354  may be folded once wave-cut  152  is applied and formed in bags  354  but bags are shown unfolded for ease of illustration. 
         [0126]    Returning now to  FIG. 18 , an individual bag  354   a  is shown. Each wave-cut trash bag  354   a  comprises a front panel and a rear panel, or first and second panels, formed from opposing sides of the collapsed tube  110 . However, the front and rear panels are mirror images of each other and hence only a front panel is illustrated in  FIG. 18 .  FIG. 18  shows trash bag  354   a  with a first side edge  112   b  defined by the first edge  112  of the collapse tube  110  and a second side edge  114   b  defined by the second edge  114  of the collapsed tube  110 . The trash bag  354  is further shown with a bottom seal  142   a  defined by one seal of the closely spaced sets of seals  142 . A bag bottom  144   a  or bottom edge is shown as defined by one of the perforation lines  144 . The bag top  152   a  can be defined by one of the wave-cuts  152 . The bag top  152   a  has a wave-cut profile due to the wave-cut  152 . The bag top  152   a  is defined on both the front panel and back panel of the bag  354   a  with the bag top  152   a  defining a bag opening. 
         [0127]    As illustrated by  FIGS. 13, 17 and 18 , an embossed section  358  of the trash bag  354   a  can be comprised of an entire embossed section  316  of the collapsed tube  110 . A plurality of lobes  156  can be defined by the wave-cut profile  152   a  as shown in  FIG. 18 . The plurality of lobes  156  may also be referred to as tie-flaps. The wave-cut profile height H is shown as the vertical distance from a top of the wave-cut profile to a bottom of the wave-cut profile, the wave-cut profile height H equal to a peak-to-peak amplitude of the wave shape of the wave-cut profile. Furthermore, as best illustrated by  FIG. 18 , wave-shaped profile  152   a  comprises one or more crests  156   a , or peaks of the wave shape, and troughs  156   b , or valleys, of the wave shape of the wave-shaped profile. 
         [0128]    Further shown in  18 , embossed section  358  is offset from wave-cut  152   a . Embossed section  358  is shown between perforation line  144   a  and wave-cut  152   a  so that the embossed section  358  is located in the body of bag  354   a . Embossed section  358  is shown extending from the first side edge  112   b  to the second side edge  114   b  and from a lower embossment boundary  372  to an upper embossment boundary  370 . Embossed section  358  is further shown below the troughs  156   b  of the wave-shaped profiled  156 . The bag body can be located between the lower extent of the bag top  152   a  and the bag bottom  144   a.    
         [0129]      FIG. 18  further illustrates the upper embossment boundary  372  below the troughs  156   b  of the wave-shaped profile  152   a  and the lower embossment boundary  374  above the bottom seal  142   a . Both upper and lower boundaries  370  and  372  are shown extending from the first side edge  112   b  to the second side edge  114   b  and generally parallel to the bottom seal  142   a  and hence generally perpendicular to the two side edges  112   b  and  114   b.    
         [0130]    Further shown in  FIG. 18  above upper embossment boundary  370  and below lower embossment boundary  372  are upper and lower unembossed sections  362  and  364 . Unembossed sections  362  and  364  are substantial flat and devoid of embossments since the embossing operation  320  has not been applied to these areas of the polymeric film of the collapsed tube  110 . The unembossed sections  362  and  364  are generally flat in comparison to the embossed section  358  but can be expected to have a certain amount of surface roughness and unevenness due to typical surface variations of a polymeric film produced by a blown film extrusion process. Both unembossed sections  362  and  364  are shown extending from the first side  112   b  to the second side edge  114   b  of bag  354   a . Upper unembossed section  364  is further shown extending from the upper embossment boundary  370  to the crests  156   b  of the wave-cut profile and lower unembossed section  362  is shown extending from the lower embossment boundary  372  to the bag bottom or bottom edge  144   a.    
         [0131]    Further shown in  FIG. 18  are embossed transition zones  358   a  and  358   b . It has been determined that when a polymeric film undergoes an embossing operation as discussed above, the film undergoes a gradual transition from an un-embossed section to a fully embossed section of film. This transition is represented by the transitions zones  358   a  and  358   b  shown in  FIG. 18 . Due to the gradual engagement of the intermeshing rollers  322   a  and  322   b  of the collapsed tube  110 , the linear embosses adjacent to upper and lower embossment boundaries  370  and  372  taper with a decreasing height as the linear embosses extend from within the embossed section  358  towards the unembossed sections  362  and  364  above and below the embossed section  358 . 
         [0132]    In a particular example of the embodiment of  FIG. 17  of the pair of bags  354 , the perforation lines  144  can be 113 inches away from each other. Each wave-cut  152  can also be separated from adjacent wave-cuts  152  by 113 inches. The peak-to-peak amplitude of the wave-cut  152   a , H, can be about 5 inches which is shared between the two bags. Hence, the height of an individual bag  354   a  can be about 54 inches. The upper embossment boundary  370  can be about 2 inches below the troughs  156   b  of the wave-cut  152   a  and the lower embossment boundary  372  can be about 2 inches above the bottom perforation or edge of bag  144   a . These dimension results in the embossed section  358  having a height of about 45 inches. It is further contemplated that the embodiment shown in  FIGS. 17 and 18  may also be implemented on a wave-cut trash bag having dimensions of a typical kitchen trash bag. 
         [0133]    As previously noted, the specific embodiments depicted herein are not intended to limit the scope of the present invention. Indeed, it is contemplated that any number of different embodiments may be utilized without diverging from the spirit of the invention. Therefore, the appended claims are intended to more fully encompass the full scope of the present invention.