Composite Heat Seal Structure Adaptable to Step Portion Formed By Piling

Abstract

A compound heat seal structure that, when heat-sealing a bag with a stacked area level difference, reliably seals even a section having different level and that can be easily opened. A compound heat seal structure is provided as a peelable seal in a band shape on a bag and a linear heat seal is added as a peelable seal in that band-shaped peelable heat seal in the longitudinal direction thereof.

I claim: 
     
         1 . A composite heat seal structure of a package, the heat seal comprising:
 a band-shaped peelable seal defining a longitudinal direction along its length; and   a linear peelable heat seal in the band-shaped peelable heat seal in said longitudinal direction.   
     
     
         2 . The composite heat seal structure as set forth in  claim 1 , wherein:
 the package is a packaging bag; and   the band-shaped peelable seal is a heat seal on at least one side of said packaging bag.   
     
     
         3 . The composite heat seal structure as set forth in  claim 2 , wherein the band-shaped peelable heat seal has a width of 3-20 mm and the linear heat seal has a width of 0.05-2 mm and a depth of 0.05-2 mm. 
     
     
         4 . The composite heat seal structure as set forth in  claim 1 , wherein the number of the linear peelable heat seal is one. 
     
     
         5 . The composite heat seal structure as set forth in  claim 1 , wherein the linear peelable heat seal is located at a position 60-90% of a total width from an inner edge of the band-shaped peelable seal. 
     
     
         6 . The composite heat seal structure as set forth in  claim 2 , wherein the package is pillow-type bag or a gusset bag. 
     
     
         7 . A method of heat-sealing a heat-sealing material using a heat seal apparatus which nips the heat-sealing material between a pair of heating bodies, wherein a linear rib having an arc-shaped cross section with a height of 0.05-2 mm is provided in the longitudinal direction of one of the heating surfaces, and an elastic body is mounted on the other heating surface, the method comprising:
 heat sealing the heat-sealing material with the heating bodies at a temperature to forma peelable seal.   
     
     
         8 . A method of heat-sealing as set forth in  claim 7 , wherein heat sealing comprises the heating at 0.1-0.3 W/cm with said linear rib. 
     
     
         9 . The method of heat-sealing as set forth in  claim 7 , wherein the elastic body has a Shore hardness of 40 A-90 A. 
     
     
         10 . The method of heat-sealing as set forth in  claim 7 , comprising:
 applying a load of 25-60 N/10 mm to the top of the linear rib when a press pressure of 0.1-0.4 MPa is applied to a 2-sheet area of said heat-sealing material.