Box bottom composite sack

Abstract

A box bottomed composite sack manufactured with a combination of monoaxially oriented tape fabric and non-oriented materials, and having a cover sheet bonded to the box bottom, is disclosed. The box bottomed sack is preferably constructed with either monoaxially oriented tape fabric or non-oriented material and can be coated on either side with a thermoplastic material such as polypropylene, polyethylene, ethylene vinyl acetate, and polyolefin to seal the sack and to facilitate bonding to the cover sheet. The cover sheet can be constructed with any suitable material, selected so that either the cover sheet or the sack body is made of monoaxially oriented tape fabric, and attached to the folded box bottom of the sack by a corresponding method for the specific cover sheet material. The cover sheet can be coated with thermoplastic material to facilitate bonding to the sack. The composite box bottomed sack does not require costly equipment to manufacture, is less susceptible to weakening due to heat treatment and is economical.

1 . A box bottomed sack comprising: 
 a sack body having one end folded into a box bottom configuration, the sack body constructed from a fabric made from materials selected from a list including materials woven from monoaxially oriented tapes, cotton, jute, hemp, nylon, and polyester; and    a cover sheet, attached to the folded end of the sack body, the cover sheet constructed from a fabric made from materials selected from a list including materials woven from monoaxially oriented tapes, cotton, jute, hemp, nylon, polyester and non woven materials including paper, film or foil, the material selected so that exactly one of the sack body and cover sheet are constructed from monoaxially oriented woven tape fabric.    
   
   
       2 . The box bottomed sack of  claim 1 , further including a liner, attached to the sack body.  
   
   
       3 . The box bottomed sack of  claim 2 , wherein the liner is open at both ends and is affixed to the ends of the sack body.  
   
   
       4 . The box bottomed sack of  claim 2 , wherein the liner has both an open end and a closed end, is larger than the sack body in at least 1 dimension, and is affixed to the sack body by its open end.  
   
   
       5 . The box bottomed sack of  claim 2 , wherein the liner is attached to the sack body by stitching.  
   
   
       6 . The box bottomed sack of  claim 2 , wherein the liner is micro perforated.  
   
   
       7 . The box bottomed sack of  claim 2 , wherein the folded end of the sack body includes a self closing valve open to the interior of the liner.  
   
   
       8 . The box bottomed sack of  claim 2 , wherein the liner has a thickness of about 5-100 μm.  
   
   
       9 . The box bottomed sack of  claim 1 , wherein the cover sheet is attached to the sack body by an attachment method selected from a list including heat sealing, gluing, sewing, tacking, taping and slit die extrusion.  
   
   
       10 . The box bottomed sack of  claim 1 , wherein at least one of the sack body and the cover sheet are laminated.  
   
   
       11 . The box bottomed sack of  claim 10 , wherein the at least one of the sack body and the coversheet are laminated with a material selected from a list including polyethylene, polypropylene, polyolefins, and ethylene vinyl acetate.  
   
   
       12 . The box bottomed sack of  claim 10 , wherein the cover sheet is attached to the sack body by fusing the sack body and the cover sheet by an method selected from a list including heat sealing, ultrasonic plastic welding, heating plate pressing, heat plate pinning, friction welding and slit die extrusion.  
   
   
       13 . The box bottomed sack of  claim 1 , wherein the folded end of the sack body includes a valve.  
   
   
       14 . The box bottomed sack of  claim 13 , wherein the valve is self closing.  
   
   
       15 . The box bottomed sack of  claim 13 , wherein the valve is disposed between the folded end and the coversheet.  
   
   
       16 . The box bottomed sack of  claim 1  including a layer of molten plastic material interposed between the folded end and the cover sheet.  
   
   
       17 . The box bottomed sack of  claim 1 , wherein the tapes in the monoaxially oriented woven tape fabric have a thickness of about 10-80 μm.  
   
   
       18 . The box bottomed sack of  claim 1 , the sack body has both ends folded into a box bottom configuration, and the sack includes a second cover sheet, attached to the second folded end of the sack body, the second cover sheet constructed from a material selected from a list including materials woven from monoaxially oriented tapes, cotton, jute, hemp, nylon, polyester and non woven materials including paper, film or foil.