Patent Publication Number: US-8535209-B2

Title: Method and system for making a stepped end

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Application No. 61/326,746, filed Apr. 22, 2010. 
    
    
     FIELD OF THE INVENTION 
     The invention relates to a method and apparatus for making a stepped end on a tube of flexible material, wherein the stepped end is adapted to be closed to provide a closed end on a bag. 
     BACKGROUND 
     U.S. Pat. No. 6,800,051 B2 and U.S. Pat. No. 4,008,850 and US 2009/0159192 A1 respectively disclose a method for making a bag having a staggered end also known as a stepped end. 
     US 2009/0159192 A1 discloses a perforation line in a web of tubular film, along which perforation line a segment is severed from the web of tubular film to form a staggered end. The perforation line is formed in a flat web of film, after which the tubular film is formed by folding side parts so as to overlap, and then simultaneously inserting the side folds and affixing a longitudinal center weld. Scoring apparatus are disclosed in U.S. Pat. No. 4,273,550 and U.S. Pat. No. 5,840,002 to make creases in the film for folding the film. 
     US 2010/0029455 A1 discloses a fabric having a layer of woven plastic bands and at least one additional material layer, and the cutting capacity of a laser can be adjusted to a thickness of the material layers to provide a perforation line. 
     A perforation line in a flat web of film is unsuited for a tube. Instead of manufacturing a flat web of film having a perforation line, a continuous tube without a perforation line can be manufactured at a high production speed, followed by cutting the tube to a desired length at the high production speed. The tube can be seamless. Alternatively, the tube can have one or more longitudinal seams as disclosed by Coating Excellence LLC in US 20080187695 A1, U.S. application Ser. No. 12/019,407, filed Jan. 24, 2008. Then it would be desirable to manufacture a stepped end on the tube, wherein the stepped end is adapted to be closed to make a bag. However, a tube does not encompass a flat web of film. It follows, It would be desirable to manufacture a staggered end, also known as a stepped end, on a tube, in order to take advantage of high speed manufacture of the tube. 
     SUMMARY OF THE INVENTION 
     The invention relates to a method and apparatus for making a stepped end on a tube of flexible material, wherein the stepped end is adapted to be closed to provide a closed end on a bag. 
     A method of making a stepped end on a tube of flexible material includes slitting the tube adjacent an open end of the tube to provide first slits beside a first panel of the tube and to provide second slits beside a second panel of the tube; trimming the first panel to a first shortened length adjacent to the open end of the tube while the first slits separate the first panel from a remainder of the tube, wherein the remainder of the tube comprises side gussets and the second panel; trimming each of side gussets to a second shortened length adjacent to the open end of the tube while the second slits separate each of the side gussets from the second panel, wherein the second shortened length is longer than the first panel and shorter than the second panel; and applying adhesive material on the tube above and below a fold line across the tube, wherein the tube is adapted to be folded along the fold line, and the adhesive material is adapted to form an adhesive to adhesive seal above and below the fold line while the tube is folded to provide a closed stepped end for a bag. 
     An apparatus for making a stepped end on a tube of flexible material includes a tube slitting station having a slitting tool with double edge slitting blades penetrating through the tube to provide respective slits beside a first panel and beside a second panel, respectively; a first trimming station trimming a first panel of the tube to a first shortened length, a second trimming station trimming the side gussets to a second length, wherein the second length is longer than the first shortened length of the first panel; and an adhesive applying station applying adhesive on the tube above and below a fold line across the tube, wherein the tube is adapted to be folded along the fold line, and the adhesive material is adapted to form an adhesive to adhesive seal above and below the fold line while the tube is folded to provide a closed stepped end for a bag. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the invention will now be described by way of example with reference to the accompanying drawings. 
         FIG. 1  is an isometric view of a tube having a first panel and a second panel, and side gussets, wherein the tube is adapted for making a bag. 
         FIG. 2  is an isometric view of a tube manufactured with a stepped end. 
         FIG. 2A  is an isometric view of another embodiment of a tube manufactured with a stepped end. 
         FIG. 3  is an isometric view of an apparatus for making a stepped end on a tube, and further disclosing a tube slitting station of the apparatus. 
         FIG. 4  is an isometric view of a first panel trimming station of the apparatus of  FIG. 3 . 
         FIG. 4A  is a view similar to  FIG. 4 , and further disclosing a shortened end of a first panel of the tube. 
         FIG. 5  is an isometric view of a second panel trimming station of the apparatus of  FIG. 3 . 
         FIG. 5A  is a view similar to  FIG. 5 , and further disclosing a shortened end on each of the side gussets of the tube. 
         FIG. 6  is an isometric view of a creasing station and an adhesive applying station of the apparatus of  FIG. 3 . 
         FIG. 7  is an isometric view of the stepped end of the tube of  FIG. 6  being folded and sealed. 
         FIG. 8  is an isometric view of a slitting station for slitting side gusset folds on the tube of  FIG. 2A . 
         FIG. 8A  is a view similar to  FIG. 8  indicating an operation of the slitting station of  FIG. 8 . 
         FIG. 8B  is a view similar to  FIG. 8  indicating another operation of the slitting station in  FIG. 8 . 
         FIG. 9  is an isometric view of an embodiment of a gusset trimming station. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  discloses a tube  100  of flexible polymeric material, wherein the tube  100  is formed with a first side gusset  110  and a second side gusset  110 . Side edges  112 ,  112  of a first panel  106  are connected to the first side gusset  110  and the second side gusset  110 , respectively. Side edges  114 ,  114  of a second panel  108  are connected to the first side gusset  110  and the second side gusset  110 , respectively. The first side gusset  110  and the second side gusset  110  are foldable inward along longitudinal creases or folds  116 ,  116  to flatten the tube. The gussets  110 ,  110  fold or crease along the side edges  112 ,  112  and the side edges  114 ,  114 . 
       FIG. 1  discloses the tube  100  having an open end  122  encircled by a first panel  106 , a second panel  108  and the side gussets  110 ,  110 . The first panel  106  refers to a front panel of the bag while the second panel  108  refers to a back panel of the bag. Alternatively, the first panel  106  refers to a back panel of the bag while the second panel  108  refers to a front panel of the bag. 
     In  FIG. 2  and  FIG. 2A , respective first sections  118 ,  118  of the side gussets  110 ,  110  are adjacent to the first panel  106 . Respective second sections  120 ,  120  of the side gussets  110  are adjacent to the second panel  108 . The side gussets  110  are folded along the folds  116  of  FIG. 1 . The first sections  118 ,  118  and the second sections  120 ,  120  fold inwardly along the folds  116 ,  116 , respectively, and are in an inwardly folded orientation between the first panel  106  and the second panel  108  while the tube  100  is flat. Each side gusset  110  is adapted to unfold outwardly from between the first panel  106  and the second panel  108  to expand the bag interior. In an embodiment of  FIG. 2A , the second sections  120 ,  120  of the side gussets  110 ,  110  are shorter than the first sections  118 ,  118  of the side gussets  110 ,  110 , and are made as described with reference to  FIGS. 8 and 9 . 
     An embodiment of the tube  100  is formed as a laminated tube  100  that has a woven inner layer  102 , a portion of which is illustrated to comprise a tight basket weave of thin, flexible, elongated strips of a polymeric material, for example, polypropylene. The inner layer  102  advantageously comprises a woven seamless tube that is highly flexible due to the weave. The laminated tube  100  has at least one outer layer  104  of a printable nonwoven polymeric material, for example, polypropylene film that is capable of being printed with graphics using water based pigments or solvent based pigments. 
     In an embodiment of the invention, the outer layer  104  is reverse printed on an inside surface of a first polypropylene film. In another embodiment, a second layer of polypropylene film is laminated to the first polypropylene film, with the printed surface between the first and second layers of polypropylene film. Alternatively, the second layer of polypropylene film can be printed with the graphics. 
     After printing, the outer layer  104 , and each second layer of polypropylene film, if present, and the woven inner layer  102  are laminated, for example, by applying a solventless adhesive material or solvent based adhesive material between the layers to be laminated, and applying heat and pressure to laminate each outer layer  104 , second layer and the inner layer  102  and form the continuous laminated tube  100 . The woven inner layer  102  can be seamless tubular, while the outer layer  104  and each second layer of polypropylene film can overlap and form a lengthwise closed seam, that is adhesively sealed shut to form a seamed tubular construction, further described by US 20080187695 A1, U.S. application Ser. No. 12/019,407, filed Jan. 24, 2008. 
     Alternative embodiments of the tube  100  are fabricated with one or more nonwoven polypropylene films to provide a nonwoven inner layer  102  and a nonwoven outer layer  104 . 
     Further embodiments of the tube  100  comprise, a seamless blown tube, a seamless woven tube and a tube manufactured from flat sheets laminated together to form a seamed tubular construction. Embodiments of the tube comprise, a seamless blown tube, a seamless woven tube and a tube manufactured from flat sheets laminated together to form a seamed tubular construction. Further, a particular embodiment of a tube includes a seamless woven tube of polypropylene or other polyolefin material, which is desired for its tensile strength in order to package and store heavy contents in granular form, such as, dog food, cereals, grains and construction materials. 
       FIG. 2  discloses the tube  100  wherein the open end  122  of the bag is pinch closed by closing the first panel  106  and the second panel  108  against each other at their end edges adjacent the open end  122 . The tube  100  is made with a stepped, or step cut construction at the open end  122 , wherein a portion of the first panel  106  is removed by severing, cutting or hot knife, and wherein the first panel  106  is made shorter than a longer portion  502  of the second panel  108  at the open end. Further, a portion of each of the side gussets  110 ,  110  is removed, wherein the side gussets are made longer than the first panel  106  and shorter than the second panel  108 . The longer portion  502  provides a foldable flap portion  502  on the second panel  108 . As a result, a stepped end  122  is formed on the tube  100 . Although, the stepped end  122  is disclosed on an embodiment of the tube  100  in  FIG. 1 , the stepped end  122  can be made on any embodiment of a tube of flexible polymeric material intended for making a bag. 
     First, the tube  100  in  FIG. 2  is made with a stepped end  122 . After making the stepped end  122 , a first layer  600  of an adhesive material is provided on the first panel  106  of the tube  100 . Further, a second layer  602  of an adhesive material is applied on the sealing flap portion  502 . The second layer  602  can comprise an additional amount of the first adhesive material, or alternatively, an amount of a second adhesive material different from the first adhesive material. 
     An apparatus and method will now be described for making the stepped end  122  of the tube  100 . Advantageously the tube  100  eliminates a perforated line to make the stepped end. Further, advantageously the apparatus and method applies to any embodiment of a tube of flexible polymeric material intended for making a bag, including, but not limited to an embodiment of the tube  100  described in  FIG. 1 . 
       FIG. 3  discloses the tube  100  formed with a slit portion  208  of the second panel  108  adjacent to the open end  122  of the tube  100 . The second panel  108  has first corresponding slits  210 ,  210  along the side edges  114 ,  114  thereof. The first corresponding slits  210 ,  210  are adjacent to the open end  122  and extend into the open end  122 . The first corresponding slits  210 ,  210  separate the slit portion  208  of the second panel  108  from the side gussets  110 ,  110 . 
       FIG. 3  discloses a slit portion  300  of the first panel  106  adjacent to the open end  122 . The first panel  106  has second corresponding slits  302 ,  302  along the side edges  112 ,  112  thereof. The second corresponding slits  302 ,  302  are adjacent to the open end  122  and extend into the open end  122 . The second corresponding slits  302 ,  302  separate the slit portion  300  from the side gussets  110 ,  110 .  FIG. 3  discloses the slits  302 ,  302  are longer than the shorter slits  210 ,  210 . 
       FIG. 3  discloses the tube  100  in an apparatus  400 . The tube  100  is conveyed, for example, by a continuous or intermittent or segmented belt conveyor  428 , and is indexed into position in front of a slitting station  402 . The slitting station  402  of the apparatus  400  is provided with a slitting tool  404  disclosed in its home position. The slitting tool  404  has spaced apart, double edge slitting blades  406 ,  408 . Although the slitting blades  406 ,  408  are disclosed as fixed flat blades, they can take the form of rotary blades or reciprocating blades. 
     In  FIG. 3 , the open end  122  of the tube  100  is opened and maintained open, for example, by blowing air under pressure into the open end  122  of the tube  100  or by surrounding the tube  100  in a suction chamber, not shown. While the tube  100  is open, the slitting tool  404  is initially in its home position disclosed by  FIG. 3 . Then the slitting tool  404  is indexed or displaced from its home position toward and into the open end  122  of the tube  100 , in a direction disclosed by the arrow  410 , to a first tool position to insert the slitting blades  406 ,  408  into the open end  122  of the tube  100 . 
     Then while the slitting tool  404  is inside the tube  100 , the tool slitting  404  is indexed or displaced, relative to the tube  100 , in a forward direction indicated by the forward pointing arrow  412 . Thereby, the slitting tool  404  is indexed or displaced to a stationary second tool position while the slitting blades  406 ,  408  have forward slitting edges  414 ,  416  that perform slitting through a first pair of the side edges  112 ,  114  of the first panel  106  and the second panel  108 , respectively. The forward slitting edges  414 ,  416  serve to provide a first pair of forward respective slits  210 ,  302  beside the panels  106 ,  108 . 
     The tube  100  is conveyed or displaced in a forward direction indicated by the arrow  418 , provided that the slitting tool  404  is displaced in a forward direction  412  faster, relative to forward displacement of the tube  100 , while the forward slitting edges  414 ,  416  perform slitting through a first pair of the side edges  112 ,  114  of the first panel  106  and the second panel  108 , respectively. Alternatively, the tube  100  can be stationary while the slitting tool  404  is displaced in a forward direction  412  while the forward slitting edges  414 ,  416  perform slitting through a first pair of the side edges  112 ,  114  of the first panel  106  and the second panel  108 , respectively. 
     Then, while the tube  100  is being conveyed in a forward direction  418 , the slitting tool  404  while inside the tube  100 , and is indexed in a reverse or rearward direction indicated by the rearward pointing arrow  420 , to return to its first tool position while inside the tube  100 . The slitting blades  406 ,  408  have rearward slitting edges  422 ,  424  that perform slitting through a second pair of the side edges  112 ,  114  of the first panel  106  and the second panel  108 , respectively. Thereby the rearward slitting edges  422 ,  424  provide a second pair of the respective slits  302 ,  210  beside the panels  106 ,  108 . Then the tube  100  continues in the forward direction  418 , while the slitting tool  404  is being indexed in a rearward direction indicated by the rearward pointing arrow  426  to its home position shown in  FIG. 2 . The slitting tool  404  can bias the flexible gussets  110 ,  110  out of the way, as the slitting tool  404  returns to its home position disclosed in  FIG. 3 . The tube  100  continues to be conveyed in the forward direction  418 , and leaves the slitting tool  404 . By repeating the operation of the apparatus  400  as described herein, multiple tubes  100  in succession are provided with the slits  210  and  302 . 
       FIG. 4  discloses the apparatus  400  having a first panel trimming station  500 . The tube  100  continues to be conveyed by the belt conveyor  428  of  FIG. 3  in a forward direction indicated by the arrow  418  in  FIG. 3 , such that belt conveyor  428  extends beyond the slitting station  402  of  FIG. 3  to convey the tube  100  from the slitting station  402  of  FIG. 3  to the first panel trimming station  500  of  FIG. 4 . At the first panel trimming station  500 , the tube  100  is supported on a table or rotary knife anvil  504 , disclosed in exploded configuration for clarity. The tube  100  is folded along an edge  506  of the table or anvil  504 , which folds the side gussets  110 ,  110  and the slit portion  208  of the second panel  108 , down and away from the slit portion  300  of the first panel  106 . The slits  302 ,  302  separate the slit portion  300  of the first panel  106  from a remainder of the tube  100 , wherein the remainder of the tube  100  includes the side gussets  110 ,  110  and the slit portion  208  of the second panel  108 . The first panel trimming station  500  includes a cutting blade  508  which cuts through the first panel  106  and performs trimming. The terminology trimming means to shorten in length, by severing, cutting or hot knife, which is accomplished, for example, by a knife cutting blade or rotary cutting blade, pair of shears, punch press or an equivalent tool or machine. 
     Further,  FIG. 4  discloses the side gussets  110 ,  110  being pivoted away from the slit portion  300  of the first panel  106 . The slitted portion  208  of the second panel  108  is behind the pivoting gussets  110 ,  110 . For this reason, the slitted portion  208  of the second panel  108  pivots and moves away with the side gussets  110 ,  110 . Both the slitted portion  208  of the second panel  108  and the side gussets  110 ,  110  are folded downwardly away, while the first panel  106  is trimmed. 
       FIG. 4A  discloses the slit portion  300  of the first panel  106  being removed and discarded. As a result, the first panel  106  is trimmed to a first shortened length  124 . As disclosed by  FIG. 2 , the first shortened length  124  of the first panel  106  will be adjacent to the open end  122  of the tube  100 . 
       FIG. 5  discloses the apparatus  400  having a second panel trimming station  604 . The tube  100  continues to be conveyed by the belt conveyor  428  of  FIG. 3  in a forward direction indicated by the arrow  418  in  FIG. 3 , such that belt conveyor extends beyond the slitting station  402  of  FIG. 3  to convey the tube  100  from the slitting station  402  of  FIG. 3  to the first panel trimming station  500  of  FIG. 4 , and then to the second panel trimming station  604  in consecutive order. The tube  100  is conveyed by the belt conveyor  428  of  FIG. 4  from the first panel trimming station  500  of  FIG. 4  to the second panel trimming station  604  of  FIG. 5 . At the second panel trimming station  604 , the tube  100  is supported on a table or rotary knife anvil  606 . The tube  100  is folded along an edge  608  of the table  604 , which folds the sated portion  208  of second panel  108 , down and away from the side gussets  110 ,  110 . The slits  210 ,  210  separate the side gussets  110 ,  110  from the remainder of the tube  100 , wherein the remainder of the tube  100  includes the second panel  108 , and especially the slit portion  208  of the second panel  108 . The second trimming station  604  includes a cutting blade  610  which cuts through the side gussets  110 ,  110 , and performs trimming to cut through the side gussets  110 ,  110  to cut and remove sections  612 ,  612  of the side gussets  110 ,  110 . 
       FIG. 5A  discloses the sections  612 ,  612  being removed and discarded. As a result, each of the side gussets  110 ,  110  are trimmed to a second shortened length  126 ,  FIG. 2 . As disclosed by  FIG. 2 , the second shortened length  126  of each of the side gussets  110 ,  110  will be adjacent to the open end  122  of the tube  100 . 
     The side gussets  110 ,  110  become longer than the first panel  106  adjacent to the open end  122  of the tube  100 , and the side gussets  110 ,  110  become shorter than the second panel  108  adjacent to the open end  122  of the tube  100 , which comprises a stepped end  122  of the tube  100   FIG. 2 . The second panel  108  provides a sealing flap portion  502  adjacent to the stepped end  122  of the tube  100 . After formation of the stepped end  122  of the tube  100 , the tube  100  is flattened by inwardly folding the side gussets  110 ,  110 . 
     In  FIG. 6 , a fold line  206  across the tube  100  indicates a line along which the tube  100  can be folded. To form the fold line  206  with an optional crease, the flattened tube  100  is conveyed through a scoring apparatus  700  of the apparatus  400 , which provides a crease along the fold line  206  across the tube  100 . A scoring apparatus  700  is disclosed in  FIG. 6  in schematic representation of a commercially available scoring apparatus, for example, as disclosed in U.S. Pat. No. 4,273,550 and U.S. Pat. No. 5,840,002. As a result, the invention provides a method of making a stepped end  122  and a fold line  206  with an optional crease on a tube  100  of flexible material for a tubular bag. 
     Further,  FIG. 6  discloses a method of making a tube  100  of flexible material with a stepped end  122  that folds to close the stepped end  122  and form a bag, and adhesive material applied as layers  600 ,  602  for sealing the stepped end  122 .  FIG. 6  discloses a process of applying a layer  602  of an adhesive material on the sealing flap portion  502 . Further  FIG. 6  discloses applying a layer  600  of additional or further adhesive material below the sealing flap portion  502 , such that the tube  100  has adhesive material above the fold line  206 , on the gussets  110  and the panel  106 , and below the fold line  206 , on the panel  106 . The adhesive material layer  600  and the adhesive material layer  602  are applied, while the tube  100  is flat, by an adhesive material applicator  702  including, but not limited to a roller, brush or spraying apparatus. The adhesive material layer  600  and the further adhesive material layer  602  are applied simultaneously to attain manufacturing speed. The adhesive material layer  600  and the further adhesive material layer  602  are applied as fluent compositions including emulsions or solutions constituted in a fluid including, but not limited to water or a chemical solvent. Then the adhesive material layer  600  and the further adhesive material layer  602  are dried in a heated oven to drive off the fluent substances. The adhesive material layer  600  and the further adhesive material layer  602  are the same material or, alternatively, are different materials, which are capable of forming moisture and water resistant, heat activated adhesive-to-adhesive seals. 
     The adhesive-to-adhesive seal is formed by heating the adhesive material layer  600  and the further adhesive material layer  602  to a melt flow temperature at which they attain a melt flow, adhesive state. The adhesive material layer  600  and the further adhesive material layer  602  have respective melt flow temperatures of about 300° F. maximum to avoid heating the polymeric material of the tube  100  to its melt flow temperature above the 300° F. threshold temperature. The adhesive material corresponding to each of the adhesive layers  600 ,  602  on the tube  100  has a coating weight of at least 5-10 lb./ream on each of opposing surfaces to form an adhesive-to-adhesive seal between the opposing surfaces of about 10 lb./ream coating weight to about 20 lb./ream coating weight. The adhesive material layers  600 ,  602  are activated to an adhesive state by applying heat at a heat activation temperature below the heat activation temperatures of standard or traditional hot melt adhesives or solvent based adhesives that can seal traditional paper and polymer laminated bags without damaging the paper layers, but which exceed the softening point temperature T g  of polymeric bags  100  fabricated without paper layers. The standard or traditional hot melt adhesives cannot be combined with polypropylene bags  100  because the temperatures needed to activate the adhesives are destructive to the PP material structure. 
     Polypropylene has a melting point temperature of about 160° C. (320° F.), as determined by differential scanning calorimetry (DSC). The softening point temperature of polypropylene is below its melting point temperature. Thus, a polypropylene tube  100  can be heated to a temperature below its softening point temperature without causing heat damage of the polypropylene material. 
     One suitable adhesive material for heat sealing polyolefin films of the tube  100  comprises a water based emulsion of triethylamine adhesive commercially available as AQUAGRIP® 19566F, manufactured by Bostik, Inc., 11320 Watertown Plank Road, Wauwatosa, Wis. 53226 USA. Another embodiment of a hot melt adhesive for heat sealing polyolefin films of the tube  100  comprises a hot melt adhesive H9463 available commercially from Bostik, Inc. Wauwatosa, Wis. 53226, USA. Another embodiment of a hot melt adhesive for heat sealing polyolefin films of the tube  100  comprises a hot melt adhesive H9477 Generation II of H9463 now or soon to be available commercially from Bostik, Inc. Wauwatosa, Wis. 53226, USA, wherein the adhesives per se form no part of the present invention separate from being a structural component of the tubes disclosed herein. 
     Another embodiment of a suitable adhesive material for heat sealing polyolefin films of the tube  100  comprises an aqueous based dispersion or emulsion as an opaque liquid or fluid of an ethylene copolymer or ethylene copolymers, butyl acetate and acetaldehyde, which is commercially available as the product name ROBOND™ HS 37-140 adhesive material manufactured by Rohm and Haas Company, 100 Independence Mall West, Philadelphia, Pa. 19106-2399 USA. Another embodiment of a suitable adhesive material for heat sealing polyolefin films of the tube  100  comprises an aqueous based dispersion or emulsion as an opaque liquid or fluid, including an ionomer dispersion in water, based upon Surlyn® ionomer resin, and which can be diluted or thickened or crosslinked for enhanced properties, and which is commercially available as the product name ADCOTE™ 37-220 Heat Seal Coating manufactured by Rohm and Haas Company, 100 Independence Mall West, Philadelphia, Pa. 19106-2399 USA, wherein the adhesives per se form no part of the present invention separate from being a structural component of the tubes disclosed herein. 
     Another embodiment of a suitable adhesive material for heat sealing polyolefin films of the tube  100  comprises an aqueous based dispersion or emulsion as an opaque liquid or fluid, including water, acrylic polymer, polyester polyurethane resin, formaldehyde, ammonium hydroxide, alumina and further including ammonia as a combustion product, which is commercially available as the product name NWC 23526K (and NWC 23526KC) FDA WATER BASE HEAT SEAL FOR POLYWOVEN™ adhesive material, product code 728575, manufactured by ASHLAND Inc. P.O. Box 2219, Columbus, Ohio 43216, USA, wherein the adhesive per se forms no part of the present invention separate from being a structural component of the tubes disclosed herein. 
     Another embodiment of a suitable adhesive material for heat sealing polyolefin films of the tube  100  comprises a liquid state, acrylated epoxy based adhesive commercially available as the product name, VERSA-WELD™ 70-7879 adhesive material manufactured by Henkel Corporation P.O. Box 6500; 10 Finderline Avenue, Bridgewater, N.J. 08807 USA, wherein the adhesive per se forms no part of the present invention separate from being a structural component of the tubes disclosed herein. 
     The embodiments of adhesive materials  600 ,  602  as a structural component of the bags includes 1.75 grams adhesive material per bag applied wet, solubilized in water, assuming an 18 inch wide bag and a 3 inches wide stripe of adhesive on the bag, which is equivalent to 0.6 grams per bag dry or about 10.6 lbs per ream dry weight coating. Once the adhesive materials  600 ,  602  are applied, they must pass under a drying system to evaporate the water and dry the adhesive layers to a stable state impervious to water, water vapor and ambient temperatures. 
     The tube  100  is adapted to be closed and sealed at one end  122  to make a bag, according to a process described as follows, a heat source including, but not limited to heated air or a hot bar applies heat to activate the adhesive materials  600 ,  602  to their respective, heat-activatable adhesive states. While the adhesive materials  600 ,  602  are in their adhesive states, the source of heat is removed and the end  122  of the tube  100  is folded on the fold line  206 , while the tube  100  is pinched closed to close and seal one end  122  of the tube  100  to make a bag with one closed end  122 , while an opposite end  128  is open. According to another embodiment, the tube  100  is open at the end  122 , and is closed and sealed at the opposite end  128 , by any known means, for example, stitching or gluing. The foldable tube  100  is flattened by folding along its gusseted side panels  110  for shipping and handling, in preparation for shipment to a location where the tube  100  is opened at one end  122  and filled with contents. The adhesive materials  600 ,  602  are in their dry, solidified states during bag filling, and are moisture and water resistant, by which the adhesive material layers  600 ,  602  avoid contamination of the bag contents. After the tube  100  has been filled with contents, the tube  100  is closed and sealed at the end  122 , according to a process described as follows, a heat source including, but not limited to heated air or a hot bar applies heat to activate the adhesive materials  600 ,  602  to their respective, heat-activatable adhesive states. While the adhesive materials  600 ,  602  are in their adhesive states, the source of heat is removed and the end  122  of the tube  100  is folded on the fold line  206 , while the tube  100  is pinched closed to hold the contents in the tube  100 . 
     Further, with reference to  FIG. 7 , while the adhesive materials  600 ,  602  are in their adhesive states, the tube  100  is folded along a fold line  206  across the tube  100 , which folds the bag panel  106  on itself, with two layers of the adhesive material  600  therebetween. Pressure is applied until an adhesive-to-adhesive seal forms by the two layers of the adhesive material, which are above and below the fold line  206  and which are between the folded panel  106 . The fold line  206  can be covered with adhesive material. Alternatively, the fold line  206  can be free of adhesive material, wherein the adhesive material that is spaced above the fold line  206  covers at least a portion of the first panel  106  adjacent the end  124  of the first panel  106  and adjacent the stepped end  122 , such that upon folding along the fold line  206 , the adhesive material on the first panel  106  adjacent the end  124  can form an adhesive to adhesive seal with the adhesive material below the fold line  206 . Further, by folding along the fold line  206 , the sealing flap  502  is folded toward the bag section  106  of the panel  106 . Pressure is applied against the sealing flap  502  until an adhesive-to-adhesive seal forms against the sealing flap  502 , and further forms above and below the fold line,  206  by the adhesive of the layers  600 ,  602 . The adhesive-to-adhesive seal is established to seal the stepped end  122  with the sealing flap portion  502 . In one embodiment of  FIG. 6 , the fold line  206  is not creased, and the tube  100  is folded without a crease. Alternatively, in  FIG. 6 , the fold line  206  can be formed as a crease. Then, the flattened and creased tube  100  is conveyed through the adhesive applicator  702  of the apparatus  400 . 
       FIG. 8  discloses an embodiment of the apparatus  400  for making a stepped end  122 ,  FIG. 2A , and more particularly, a double stepped end  122 .  FIG. 8  discloses a slitting station  802  of the apparatus  400 . The tube  100  is conveyed, for example, by a continuous or intermittent or segmented belt conveyor  428 , and is indexed into position in front of the slitting station  802  for slitting the side gusset folds  116 . 
     For purposes of illustration,  FIG. 8  discloses the tube  100  having the slits  210  and  302 . The slits  210  and  302  were provided previously by the slitting station  402 . Alternatively, the slits  210  and  302  would not be present in  FIG. 8 , in an embodiment of the invention wherein the slitting station  402  is in a sequence following the slitting station  802 . Further, for purposes of illustration,  FIG. 8  discloses the open end  122  of the tube  100  being opened, in a manner similarly as in  FIG. 3 . Alternatively, the open end  122  can be closed, at least partially, by folding, at least partially, along the gusset folds  116  of both side gussets  110 . The gusset folds  116  become slitted according to the description that follows. 
       FIG. 8  discloses the slitting station  802  of the apparatus  400  is provided with a slitting tool  804  disclosed in its home position. The slitting tool  804  has a retractable, slitting blade  806  that retracts into the tool  804 , as indicated by the arrow  808 , and alternately, extends to project from the tool  804  to perform a slitting operation. The slitting blade  806  has a sharpened, single slitting edge  810 . Further, either the slitting blade  806  or the tool  804  is reversely rotatable 180° as indicated by the arrow  812  to face the slitting edge  810  either in a forward direction indicated by the arrow  418  or in a rearward direction opposite the forward direction. Alternatively, another slitting edge  810  is on the slitting blade  806  to provide a double edge blade  806 , not shown, in order to eliminate a need for rotation of the blade  806 . 
     In  FIG. 8 , the tube  100  is being conveyed or displaced in a forward direction indicated by the arrow  418 , such that a leading edge  814  of the tube is displaced past the slitting tool  804  while the slitting edge  810  facing in a rearward direction, projects from the tool  804  and slits through the gusset fold  116  to provide a first gusset slit  816  in the gusset fold  116  at the leading edge  814 . The first gusset slit  816  divides the gusset  110  at the open end  122  into a first slitted gusset portion  118  and a slitted gusset portion  120 . 
     As disclosed by  FIG. 8A , after cutting the first gusset slit  816 , the slitting blade  806  retracts into the tool  804 , while the tube  100  continues to be displaced in the forward direction  418  until a trailing edge  818  of the tube  100  is displaced past the tool  804  having the retracted slitting blade  806 . 
     As disclosed by  FIG. 8B , after a trailing edge  818  of the tube  100  is displaced past the tool  804 , the slitting blade  806  is extended to project from the tool  804 , and simultaneously, or in sequence, the slitting blade  806  is reversed in direction to face the slitting edge  810  in the forward direction  418 . Further, the tool  804  is displaced in a forward direction indicated by an arrow  812  faster than the tube  100  is being conveyed in the forward direction  418 , while the slitting edge  810  cuts through the gusset fold  116  at the trailing edge  818  of the tube  100  to provide a second gusset slit  816  in the gusset fold  116  at the trailing edge  818 . The second gusset slit  816  divides the gusset  110  at the open end  122  into a first slitted gusset portion  118  and a slitted gusset portion  120 . Thus, both gussets  110  are divided into a first slitted gusset portion  118  and a second slitted gusset portion  120 . Then, the blade  806  retracts, and the tool  804  is displaced rearward, indicated by the arrow  820  to return to its home position, as disclosed by  FIG. 8 . At the returned home position, the blade  806  is extended outward from the tool  804 , and is reversed in direction to face the slitting edge  810  in a rearward direction, while another tube  100 , in succession to a prior tube  100 , is conveyed or displaced in a forward direction indicated by the arrow  418 , such that a leading edge  814  of said another tube  100  in succession is displaced past the slitting tool  804  while the slitting edge  810  facing in a rearward direction, projects from the tool  804  and slits through the gusset fold  116  to provide a first gusset slit  816  in the gusset fold  116  at the leading edge  814 . By repeating the operation of the apparatus  400  as described herein, multiple tubes  100  in succession are provided with a pair of gusset slits  816 ,  816 . 
     According to the following description, the tube  100  having the gusset slits  816 ,  816  is provided with a stepped end, wherein the stepped end is disclosed by  FIG. 2A . First, the tube  100  is conveyed to the first panel trimming station  500 ,  FIG. 4 , wherein the first panel  106  is trimmed to a first shortened length  124  disclosed in  FIG. 2A . Further,  FIG. 2A  discloses that the first shortened length  124  of the first panel  106  will be adjacent to the open end  122  of the tube  100 . Then, the tube  100  is conveyed to the second panel trimming station  604  in consecutive order. At the second panel trimming station  604 , each of the side gussets  110 ,  110  is trimmed to a second shortened length  126 ,  FIG. 2A . Further,  FIG. 2A  discloses that the second shortened length  126  of each of the side gussets  110 ,  110  will be adjacent to the open end  122  of the tube  100 . 
     Then, the embodiment of the tube  100  having the gusset slits  816 ,  816  is conveyed from the second panel trimming station  604  to a gusset trimming station  900 ,  FIG. 9 . At the gusset trimming station  900 ,  FIG. 9 , the tube  100  is supported on a table or rotary knife anvil  906 . The tube  100  is folded along an edge  908  of the table  906 , which folds, down and away, the slitted portion  208  of second panel  108 , which now includes an additional slitted portion  208 A. Further, such folding additionally folds the slitted portions  120 ,  120  of the two gussets  110 ,  110  down and away from the slitted portions  118 ,  118  of the two gussets  110 ,  110 . Each slitted gusset portion  120  is separated from the slitted gusset portion  118  by having the slits  210 ,  210  and the gusset slits  116 ,  116 . The gusset trimming station  900  includes a cutting blade  910  which cuts through both slitted gusset sections  118 ,  118 , and performs trimming to reduce the height of the gusset sections  118 ,  118 , as disclosed by  FIG. 2A , wherein the gusset sections  118 ,  118  have a height shorter than the gusset sections  120 ,  120 , and have a height longer than the front panel  106  adjacent the end  122  of the tube  100  that becomes a stepped end  122  of the tube  100 . Further, the stepped end  122  in  FIG. 2A  becomes a double stepped end  122 , because of the double steps in the gussets  110 . 
     After formation of the double stepped end  122  of the tube  100 , the tube  100  is flattened by inwardly folding the side gussets  110 ,  110 . To form a crease along the fold line  206 , the flattened tube  100  is conveyed through the scoring apparatus  700  of the apparatus  400 , which provides a crease along the fold line  206  across the tube  100 . Further,  FIG. 6  discloses a method of making a tube  100  of flexible material with a stepped end  122  that folds to close the stepped end  122  and form a bag, and adhesive material layers  600 ,  602  for sealing the stepped end  122 .  FIG. 6  discloses a process of applying a layer of an adhesive material layer  600  on the sealing flap portion  502 . Further  FIG. 6  discloses applying a further adhesive material layer  602  on the first panel  106  of the tube  100 . The adhesive material layer  600  and the adhesive material layer  602  are applied, while the tube  100  is flat, by an adhesive material applicator  702 . The fold line  206  can be covered with adhesive material. Alternatively, the fold line  206  can be free of adhesive material, wherein the adhesive material that is spaced above the fold line  206  covers at least a portion of the first panel  106  adjacent the end  124  adjacent the end  122 , such that upon folding along the fold line  206 , the adhesive material on the first panel  106  adjacent the end  124  can form an adhesive to adhesive seal with the adhesive material below the fold line  206 . 
     The invention provides a method and a system for making an end  122  on a tube of flexible material into a stepped end  122 , wherein the stepped end is adapted to be closed and sealed to make a bag. The invention is described in conjunction with a tube  100  having an open end  122  and an opposite end  128 . A stepped end  122  according to the invention can be provided on either end  122  or  128 . Stepped ends  122 ,  122  according to the invention can be provided on tube ends  122  and  128 , respectively. 
     This description of the exemplary embodiments is intended to be read in connection with the accompanying drawings, which are to be considered part of the entire written description. In the description, relative terms such as “lower,” “upper,” “horizontal,” “vertical,”, “above,” “below,” “up,” “down,” “top” and “bottom” as well as derivative thereof (e.g., “horizontally,” “downwardly,” “upwardly,” etc.) should be construed to refer to the orientation as then described or as shown in the drawing under discussion. These relative terms are for convenience of description and do not require that the apparatus be constructed or operated in a particular orientation. Terms concerning attachments, coupling and the like, such as “connected” and “interconnected,” refer to a relationship wherein structures are secured or attached to one another either directly or indirectly through intervening structures, as well as both movable or rigid attachments or relationships, unless expressly described otherwise. 
     Patents and patent applications referred to herein are hereby incorporated by reference in their entireties. Although the invention has been described in terms of exemplary embodiments, it is not limited thereto. Rather, the appended claims should be construed broadly, to include other variants and embodiments of the invention, which may be made by those skilled in the art without departing from the scope and range of equivalents of the invention.