Bag with Reinforcing Features

Abstract

A plastic bag with flexible sidewalls defining an interior volume for holding contents includes a reinforcing feature to resist puncture and/or rupture of the bag. The reinforcing feature may include reinforcing the portion of the bag proximate the bottom edge with additional or thicker thermoplastic material. In various embodiments, the reinforcing feature may be a multi-layer strip of plastic material attached along a bottom edge of the bag, either internally or externally, to provide additional material resistant to puncture. The reinforcing feature may be adhesively bonded, heat bonded, or cold bonded to the bag sidewalls. In other embodiments, the sheet material used to produce the bag may be made with varying thicknesses. In addition, methods of manufacturing a bag with such reinforcing features in a high speed automated process are disclosed.

1 . A thermoplastic bag comprising:
 a first sidewall made of flexible thermoplastic web material;   a second sidewall of flexible thermoplastic web material overlaid and joined to the first sidewall to provide an interior volume, the first and second sidewalls joined along a first side edge, an opposite second side edge, and a closed bottom edge, the first and second sidewalls un-joined along their respective top edges to define an opening opposite the bottom edge for accessing the interior volume;   wherein the bag includes a multi-layer reinforcing feature disposed along the interior of the closed bottom edge.   
     
     
         2 . The thermoplastic bag of  claim 1 , wherein the reinforcing feature is a reinforcing strip attached to the first and second bag sidewalls. 
     
     
         3 . The thermoplastic bag of  claim 2 , wherein the reinforcing strip is substantially aligned with the bag bottom edge. 
     
     
         4 . The thermoplastic bag of  claim 2 , wherein the reinforcing strip is raised above the bag bottom edge. 
     
     
         5 . The thermoplastic bag of  claim 2 , wherein the reinforcing strip has a height measured along the sidewall from a reinforcing strip bottom edge adjacent to the bag bottom edge to a reinforcing strip top edge distant from the bag bottom edge and a length measured from sidewall to sidewall and is bonded to the first and second sidewalls along substantially the entire height of the reinforcing strip. 
     
     
         6 . The thermoplastic bag of  claim 2 , wherein the reinforcing strip has a height measured along the sidewall from a reinforcing strip bottom edge adjacent to the bag bottom edge to a reinforcing strip top edge distant from the bag bottom edge and is bonded to the first and second sidewalls along the top height only of the reinforcing strip and not to the bag bottom edge. 
     
     
         7 . A thermoplastic bag comprising:
 a first sidewall made of flexible thermoplastic web material;   a second sidewall of flexible thermoplastic web material overlaid and joined to the first sidewall to provide an interior volume, the first and second sidewalls joined along a first sealed side edge, an opposite second sealed side edge, and a closed bottom folded edge, the first and second sidewalls un-joined along their respective top edges to define an opening opposite the bottom edge for accessing the interior volume;   wherein the bag includes a multi-layer reinforcing strip extending across the first and second sealed side edges from the bottom folded edge partially toward the opening.   
     
     
         8 . The thermoplastic bag of  claim 7 , wherein the reinforcing strip is on the exterior of the bag. 
     
     
         9 . The thermoplastic bag of  claim 7 , wherein the reinforcing strip is in the interior volume of the bag. 
     
     
         10 . The thermoplastic bag of  claim 8 , wherein the reinforcing strip has a bonding side layer facing the bag sidewalls of different composition from a release side layer facing away from the sidewalls. 
     
     
         11 . The thermoplastic bag of  claim 10 , wherein the bonding side layer has lower density than the release side layer. 
     
     
         12 . The thermoplastic bag of  claim 10 , wherein the release side layer has an anti-block agent and the bonding side layer has substantially no anti-block agent. 
     
     
         13 . The thermoplastic bag of  claim 10 , wherein the reinforcing strip is cold bonded to the interior of the bag. 
     
     
         14 . A draw tape bag comprising:
 a first sidewall made of flexible thermoplastic web material;   a second sidewall of a sheet of flexible thermoplastic web material of the same sheet folded, overlaid and joined to the first sidewall to provide an interior volume, the first and second sidewalls joined along a first sealed side edge, an opposite second sealed side edge, and a closed bottom folded edge, the first and second sidewalls un-joined along their respective top edges to define an opening opposite the bottom edge for accessing the interior volume;   at least one of the sidewalls forming a hem having a top length and extending along the open top end disposed opposite the bottom edge, the hem having a bottom length and a hem seal, the hem including one or more draw tape notches and a draw tape within the hem;   wherein the bag includes a folded multi-layer reinforcing strip extending across the first and second sealed side edges from the bottom folded edge partially toward the opening   wherein the multi-layer strip has a inner layer facing the bag sidewalls and an outer layer facing away from the bag sidewalls and the inner layer has a melting point lower than the outer layer.   
     
     
         15 . The draw tape bag of  claim 14 , wherein the reinforcing strip is folded along the bottom edge and adjacent respective outer surfaces of the first and second sidewalls. 
     
     
         16 . The draw tape bag of  claim 14 , wherein the reinforcing strip is inserted into the interior volume between the first and second sidewalls along the bottom edge. 
     
     
         18 . The draw tape bag of  claim 14 , wherein the sidewalls are formed with a plurality of patterns. 
     
     
         19 . The thermoplastic bag of  claim 14 , wherein the reinforcing strip is cold bonded to the interior of the closed bottom edge. 
     
     
         20 . The thermoplastic bag of  claim 19 , wherein the reinforcing strip is ring-rolled to the interior of the closed bottom edge.