Gusseted polymeric bag having stepped bottom hot air sealed

Abstract

The present invention concerns a gusseted flexible bag In one embodiment, the flexible bag of the present invention is formed from the tube of material having a front side and a rear side. A pair of laterally disposed opposing gusset folds are formed in the tube along its sides. Each of the folds has a longitudinal crease. The bag further has a rear side flap extending from the rear side of the bag across the width of the tube which is folded over onto and hot air sealed to the front side of the tube of material. The gussets each have a slit approximate a first end of the tube thereby forming a front side flap. A front side flap may also be manufactured, if desired, which is then folded over when the rear side flap is folded so that the front side flat rests under the rear side flap. The rear side flap is hot air sealed to the front side of the bag with the front side flap being sealed therebetween. In the preferred embodiment the tube of material comprises polypropylene film on the exterior of the tube and woven polypropylene film on the interior of the tube.

1 . A flexible bag formed from a tube of material and having a front side and a rear side, and a pair of opposing gusset folds, each of said folds having a longitudinal crease and a slit proximate a first end of the tube and a strip of the material removed from the front side of the bag proximate the end of the tube, thereby forming a rear side flap which is folded over to the front side of the bag. 
     
     
         2 . The flexible bag of  claim 1  wherein said tube of material comprises polypropylene film and woven polypropylene film. 
     
     
         3 . The flexible bag of  claim 2  wherein the bag has an inner surface of woven polypropylene and an outer surface of polypropylene. 
     
     
         4 . The flexible bag of  claim 2  wherein said woven polypropylene film on said inner surface of said bag is sealed to said polypropylene film on said outer surface of said bag. 
     
     
         5 . The flexible bag of  claim 2  wherein said rear side flap has a length of 1.5″+/−0.5 inches. 
     
     
         6 . The flexible bag of  claim 1  wherein said tube of material is 5 millimeters to as much as 50 millimeters in thickness. 
     
     
         7 . The flexible bag of  claim 2  wherein said polypropylene film is 5+/−20 millimeters in thickness and said woven polypropylene film is 5+/−20 millimeters in thickness. 
     
     
         8 . The flexible bag of  claim 2  wherein said woven polypropylene film is sealed to said polypropylene film across substantially all of the inside surface of the woven polypropylene film. 
     
     
         9 . The flexible bag of  claim 2  wherein said polypropylene film is biaxially oriented polypropylene. 
     
     
         10 . The flexible bag of  claim 2  wherein said polypropylene film is sealed to said woven polypropylene film by means of an intermediate layer of polyethylene and ethylene vinyl acetate. 
     
     
         11 . The flexible bag of  claim 1  and further comprising a reclosable fastener assembly disposed proximate the top of said bag on the inside surface thereof which may be selectively used to manually open and close said bag. 
     
     
         12 . The flexible bag of  claim 11  wherein said reclosable fastener assembly is disposed within said bag and said bottom surface of said bag has a series of perforations providing access to said reclosable fastener assembly from the exterior of said bag. 
     
     
         13 . The flexible bag of  claim 11  wherein said bag has a score line on the inner surface of said bag proximate said reclosable fastener assembly for providing selective manual access to said reclosable fastener assembly for the manual opening and closing of said reclosable fastener assembly and thereby providing access to the contents of said bag. 
     
     
         14 . The flexible bag of  claim 1  wherein said tube of material comprises an exterior layer of heat sealable polymer for facilitating heat sealing of the front and rear flaps of said bag. 
     
     
         15 . The flexible bag of  claim 14  wherein said heat sealable polymer comprises a blend of polyethylene and ethylene vinyl acetate. 
     
     
         16 . A method of sealing a bag, formed from a tube of material and having a front side and a rear side and a pair of opposing inwardly tending gusset folds, each of said folds having a longitudinal crease said method comprising the steps of:
 opening said tube of material so as to separate said front side from said rear side;   slitting a portion of each of said creases proximate a first end of said tube parallel to the longitudinal axis of said crease thereby obtaining said front and rear plies;   trimming a strip of material from the rear surface of said tube and from the gussets proximate said first end of said tube so as to form a bottom flap;   removing the trimmed material;   folding the bottom flap over itself towards the remainder of the tube;   hot air sealing said bottom flap to the bag so as to seal the bottom of said bag;   cutting across said tube so as to form a bag sealed at one end.   
     
     
         17 . The method of  claim 16  wherein said tube of material comprises woven polypropylene on the inside of said tube and polypropylene film on the outside of said tube, said folding of said bottom flap resulting in the woven polypropylene on the bottom flap being heat sealed to the polypropylene on the outside of the tube. 
     
     
         18 . The method of  claim 16  wherein said bottom flap is plasma treated prior to folding and heat sealing to each other. 
     
     
         19 . The method of  claim 16  further comprising forming a score line along the rear side of said tube so as to facilitate folding of said bottom flap over onto the top wall of said bag. 
     
     
         20 . The method of  claim 19  wherein said hot air is directed against the outside of said bottom flap by means of a nozzle which is pressed against the bottom flap during manufacture of said bag. 
     
     
         21 . A bag manufactured by the process of  claim 16 . 
     
     
         22 . An apparatus for manufacturing bags comprising polypropylene and woven polypropylene, said apparatus comprising:
 an unwinder for unwinding a web of laminated polypropylene and woven polypropylene;   a folder for folding said web of polypropylene into a tube;   a sealer for sealing the edges of said web of film of polypropylene and woven polypropylene together so as to form a tube.   gusset forming plows for forming gussets in the lateral sides of said tube of polypropylene and woven polypropylene;   an opener for opening said tube of polypropylene and woven polypropylene in a first end;   a slitter for slitting said gussets in said tube of polypropylene;   a trimmer for trimming said slit portions of said first end of said tube;   a picker for removing said slit portion from the remainder of said tube;   a folder for folding said bottom flap of said tube over onto the top surface of said tube and compressing said bottom flap against said top surface;   a hot air sealer for heating said bottom flap so as to form a heat seal of the first end of the tube;   a cutter for cutting said tube a desired distance from said first end of said tube so as to form a bag sealed at its first end and open at its second end.   
     
     
         23 . The bag of  claim 1  having a width of 13 inches+/−3.25 inches, a length of 27.25 inches+/−6.75 inches, and cross-section at each gusset fold of 5 inches+/−1.25 inches. 
     
     
         24 . A flexible bag formed from a tube of material and having a front side and a rear side, and a pair of opposing gusset folds, each of said folds having a longitudinal crease, said bag having a rear side flap extending from the rear side of the tube across the width of the tube and folded over onto the front side of the tube of material, the gussets each having a slit proximate a first end of the tube thereby forming a front side flap which is folded over when the rear side flap is folded with the rear side flap being hot air sealed to the front side of the bag with the front side flap being sealed therebetween. 
     
     
         25 . The flexible bag of  claim 24  wherein said tube of material comprises polypropylene film and woven polypropylene film. 
     
     
         26 . The flexible bag of  claim 25  wherein the bag has an inner surface of woven polypropylene and an outer surface of polypropylene. 
     
     
         27 . The flexible bag of  claim 25  wherein said woven polypropylene film on said inner surface of said rear side flap is sealed to said woven polypropylene film on said inside surface of said front side flap. 
     
     
         28 . The flexible bag of  claim 24  wherein said rear side flap has a length of 1.75″+/−0.25 inches and said front side flap has a length of 1.5″+/−0.5 inches. 
     
     
         29 . The flexible bag of  claim 24  wherein said tube of material is 5 millimeters to as much as 50 millimeters in thickness. 
     
     
         30 . The flexible bag of  claim 25  wherein said polypropylene film is 5+/−20 millimeters in thickness and said woven polypropylene film is 5+/−20 millimeters in thickness. 
     
     
         31 . The flexible bag of  claim 25  wherein said woven polypropylene film is sealed to said polypropylene film across substantially all of the inside surface of the woven polypropylene film. 
     
     
         32 . The flexible bag of  claim 25  wherein said polypropylene film is biaxially oriented polypropylene. 
     
     
         33 . The flexible bag of  claim 25  wherein said polypropylene film is sealed to said woven polypropylene film by means of an intermediate layer of polyethylene and ethylene vinyl acetate. 
     
     
         34 . The flexible bag of  claim 24  wherein said front side flap is sealed by means of hot melt adhesive to said rear side flap. 
     
     
         35 . The flexible bag of  claim 24  and further comprising a reclosable fastener assembly disposed proximate the top of said bag on the inside surface thereof which may be selectively used to manually open and close said bag. 
     
     
         36 . The flexible bag of  claim 34  wherein said reclosable fastener assembly is disposed within said bag and said bottom surface of said bag has a series of perforations providing access to said reclosable fastener assembly from the exterior of said bag. 
     
     
         37 . The flexible bag of  claim 34  wherein said bag has a score line on the inner surface of said bag proximate said reclosable fastener assembly for providing selective manual access to said reclosable fastener assembly for the manual opening and closing of said reclosable fastener assembly and thereby providing access to the contents of said bag. 
     
     
         38 . The flexible bag of  claim 24  wherein said tube of material comprises an exterior layer of heat sealable polymer for facilitating heat sealing of the bottom and top flaps of said bag. 
     
     
         39 . The flexible bag of  claim 38  wherein said heat sealable polymer comprises a blend of polyethylene and ethylene vinyl acetate. 
     
     
         40 . A method of sealing a bag, formed from a tube of material and having a front side and a rear side and a pair of opposing inwardly tending gusset folds, each of said folds having a longitudinal crease said method comprising the steps of:
 opening said tube of material so as to separate said front side from said rear side;   slitting a portion of each of said creases proximate a first end of said tube parallel to the longitudinal axis of said crease thereby obtaining said front and rear plies;   trimming a strip of material from the front surface of said tube and from the gussets proximate said first end of said tube so as to form a top flap and a bottom flap;   removing the trimmed material;   folding the top flap over itself towards the remainder of the tube;   folding the bottom flap over the folded top flap;   hot air sealing said top flap to said bottom flap so as to seal the bottom of said bag;   cutting across said tube so as to form a bag sealed at one end.   
     
     
         41 . The method of  claim 40  wherein said tube of material comprises woven polypropylene on the inside of said tube and polypropylene film on the outside of said tube, said folding of said top flap and said bottom flap resulting in the woven polypropylene on the top flap being heat sealed to the woven polypropylene on the bottom flap. 
     
     
         42 . The method of  claim 40  wherein said top flap and said bottom flap are plasma treated prior to folding and heat sealing to each other. 
     
     
         43 . The method of manufacture of  claim 40  wherein hot melt is applied to said top flap and said bottom flap so that when folded, compressed against each other and heat sealed said hot melt adhesive melts and seals said bag walls to each other. 
     
     
         44 . The bag of  claim 40  wherein said top flap and said bottom flap are ultrasonically sealed to each other. 
     
     
         45 . The method of  claim 40  further comprising forming a score line along the front side of said tube so as to facilitate folding of said top flap over onto the top wall of said bag. 
     
     
         46 . The method of  claim 45  wherein said hot air is directed against the outside of said bottom flap by means of a nozzle which is pressed against the top flap during manufacture of said bag. 
     
     
         47 . A bag manufactured by the process of  claim 40 . 
     
     
         48 . An apparatus for manufacturing bags comprising polypropylene and woven polypropylene, said apparatus comprising:
 an unwinder for unwinding a web of laminated polypropylene and woven polypropylene;   a folder for folding said web of polypropylene into a tube;   a sealer for sealing the edges of said web of film of polypropylene and woven polypropylene together so as to form a tube.   gusset forming plows for forming gussets in the lateral sides of said tube of polypropylene and woven polypropylene;   an opener for opening said tube of polypropylene and woven polypropylene in a first end;   a slitter for slitting said gussets in said tube of polypropylene;   a trimmer for trimming said slit portions of said first end of said tube;   a picker for removing said slit portion from the remainder of said tube;   a folder for folding a flap formed by the trimming of said tube  180 ° back onto the top surface of said tube;   a folder for folding the bottom flap of said tube over onto the folded top flap and compressing said top flap against said bottom flap;   a hot air sealer for heating said top and bottom flaps together so as to form a heat seal of the first end of the tube;   a cutter for cutting said tube a desired distance from said first end of said tube so as to form a bag sealed at its first end and open at its second end.   
     
     
         49 . The bag of  claim 24  having a width of 13 inches+/−3.25 inches, a length of 27.25 inches+/−6.75 inches, and cross-section at each gusset fold of 5 inches+/−1.25 inches. 
     
     
         50 . A bag, comprising:
 a tube having a polymeric woven tubular layer enclosed by a polymeric non-woven tubular layer, and having a first panel and a second panel and a stepped end, the stepped end including side gussets of the composite tube which are longer than the first panel and a second panel of the composite tube and having a flap extending longer than the side gussets;   an inverted zipper assembly having an inverted first flange bonded to the first panel to form a seal therebetween, and an inverted second flange;   the stepped end being folded over and bonded to said inverted second flange of the zipper assembly to form a seal therebetween.   
     
     
         51 . The bag of  claim 50 , wherein the first flange is bonded to a portion of the first panel, wherein the portion of the first panel is adjacent to the stepped end. 
     
     
         52 . The bag of  claim 50  wherein the first panel is creased and the first inverted flange is bonded to a portion of the first panel, wherein the portion of the first panel is between the crease and an edge of the first panel adjacent to the stepped end. 
     
     
         53 . A flexible bag formed from a tube consisting essentially of a material and having a front side and a rear side, and a pair of opposing, inward-tending gusset folds, each of said folds having front and rear vertical creases, said bag having at least one sealed closure formed by a method comprising the steps of:
 a. slitting each of said front creases along the longitudinal axis thereof, thereby obtaining front and rear plies;   b. forming a first rearward fold by rearwardly folding said rear plies together with said rear vertical creases such that an inner surface of said rear ply is visible; and   c. forming a second rearward fold by rearwardly folding said first fold wherein said inner surface of said rear ply lays against said rear side of said bag;   d. said material having an outer layer of polypropylene and an inner layer of woven polypropylene that are each directly sealed to one another over the entire surface area of the outer layer and the inner layer.   
     
     
         54 . The bag of  claim 53 , wherein said method further comprises the step of applying hot air to the surface of said rear ply so as to seal said inner surface to said rear side of said bag and applying hot air to the outer surface of said rear ply so as to seal said first rearward fold to said second rearward fold. 
     
     
         55 . A bag formed from a tube consisting essentially of a polyolefin material and having a front side and a rear side, and a pair of lateral, opposing, inward tending gusset folds, each of said folds having front and rear vertical creases, said bag formed by a method comprising the steps of:
 a. parting said material longitudinally along said front crease;   b. rolling a rear ply resulting from said step of parting along with said rear portion of said bag proximate to said rear ply such that a surface of said rear ply opposes the rear side of said bag; and   c. heat sealing said surface of said rear ply to the rear side of said bag;   d. said material having an outer layer of polypropylene and an inner layer of woven polypropylene that are each directly sealed to one another over the entire surface area of the outer layer and the inner layer.   
     
     
         56 . A flexible bag comprising:
 a tube consisting essentially of a polyolefin material comprising:   a front side;   a rear side;   a pair of opposing, inward-tending gusset folds, each of said folds having front and rear vertical creases and each of said folds being between said front side and said rear side;   at least one sealed closure comprising:   a front ply and a rear ply, said front ply and said rear ply being separated by a pair of slits along said front creases along longitudinal axis thereof, and said rear ply having an outer and inner surface;   a first rearward fold causing said outer surface of said rear ply to oppose a first portion of the rear side of the bag; and   a second rearward fold causing said inner surface of said rear ply to oppose a second portion of the rear side of the bag;   said material having an outer layer of polypropylene and an inner layer of woven polypropylene that are each directly sealed to one another over the entire surface area of the outer layer and the inner layer.   
     
     
         57 . The flexible bag of  claim 57  further comprising hot air sealing said inner surface to said rear ply. 
     
     
         58 . The method of  claim 16  wherein said bag is hot air sealed at a temperature of between 375 and 550° F. 
     
     
         59 . The method of  claim 40  wherein said bag is hot air sealed at a temperature of between 375 and 550° F.