Container with easily removable membrane lid

Abstract

A container such as a blow-molded plastic can has a flange encircling the top opening, and a flexible membrane lid sealed to the flange. The seal between the lid and the container does not have uniform bond strength all along its length. In particular, the seal has at least one portion having reduced width and hence lower bond strength than other portions of the seal. Consequently, initiation of peeling of the lid from the container can begin relatively easily at the lower-strength portion of the seal. Overall, however, the seal can be relatively strong to resist inadvertent detachment of the lid. Once the peeling of the lid is initiated, it becomes relatively easy to completely detach the lid.

1 . A container, comprising: 
 a container body defined by a sidewall, an opening defined in the container body, the opening circumscribed by an edge of the sidewall;    a flange joined to the edge of the sidewall, the flange encircling the opening, the flange projecting from the sidewall in a radial direction, the flange defining an outer surface that faces generally away from the container body, the outer surface having a width in the radial direction; and    a flexible membrane lid sealed to the outer surface of the flange to initially close the opening, the membrane lid being sealed to the outer surface by a seal formed between a sealant on the membrane lid and a sealant on the flange, the seal extending continuously about the opening, the seal having a width in the radial direction;    the seal having a portion of reduced width relative to other portions of the seal such that a peel force required for peeling the membrane lid from the flange has a lower value at said reduced-width portion relative to the other portions of the seal.    
     
     
         2 . The container of  claim 1 , wherein the reduced-width portion of the seal comprises a minority of a total circumferential length of the seal.  
     
     
         3 . The container of  claim 1 , wherein the width of the reduced-width portion of the seal is at least about 30 percent smaller than the width of the other portions of the seal.  
     
     
         4 . The container of  claim 1 , wherein the membrane lid defines a pull-tab portion located in registration with the reduced-width portion of the seal.  
     
     
         5 . The container of  claim 1 , wherein the reduced-width portion of the seal is provided by virtue of the width of one portion of the flange being reduced relative to other portions of the flange.  
     
     
         6 . The container of  claim 1 , wherein the reduced-width portion of the seal is provided by virtue of the sealant on at least one of the flange and the membrane being applied in a variable-width pattern.  
     
     
         7 . The container of  claim 1 , wherein the container body is an extrusion blow-molded plastic structure.  
     
     
         8 . The container of  claim 1 , wherein the flange projects radially inwardly from the sidewall.  
     
     
         9 . The container of  claim 1 , wherein the flange projects radially outwardly from the sidewall.  
     
     
         10 . The container of  claim 1 , wherein the flange is substantially planar.  
     
     
         11 . The container of  claim 1 , wherein the membrane lid comprises a substrate and a layer of the sealant at least partially covering one side of the substrate.  
     
     
         12 . The container of  claim 11 , wherein the substrate includes a barrier layer.  
     
     
         13 . The container of  claim 12 , wherein the barrier layer is selected from the group consisting of metal foil, polyethylene terephthalate, modified polyethylene terephthalate, metallized polyethylene terephthalate, metallized modified polyethylene terephthalate, polyethylene naphthalate, metallized polyethylene naphthalate, metallized polypropylene, metal oxide and silicate coated polyester, metal oxide and silicate coated polypropylene, ethylene vinyl alcohol copolymer, and mixtures thereof.  
     
     
         14 . The container of  claim 11 , wherein the sealant on the membrane lid is selected from the group consisting of hot melt glue, cold seal adhesive, polypropylene, polypropylene with mineral filler, ethylene/methacrylic acid copolymer ionomer, ethylene vinyl acetate, high-density polyethylene, low-density polyethylene, ethyl methyl acrylate, metallocenes, and mixtures thereof.  
     
     
         15 . A container, comprising: 
 an extrusion blow-molded plastic container body comprising a tubular sidewall, an end wall joined to a lower end of the sidewall, an opening defined at an upper end of the sidewall, and a flange joined to the upper end of the sidewall, the flange circumscribing the opening, the flange projecting from the sidewall in a radial direction, the flange defining an upper surface that faces generally away from the container body, the upper surface having a width in the radial direction; and    a flexible membrane lid sealed to the upper surface of the flange to initially close the opening, the membrane lid being sealed to the upper surface by a seal formed between a sealant on the membrane lid and a sealant on the flange, the seal extending continuously about the opening, the seal having a width in the radial direction;    the seal having a portion of reduced width relative to other portions of the seal such that a peel force required for peeling the membrane lid from the flange has a lower value at said reduced-width portion relative to the other portions of the seal.    
     
     
         16 . The container of  claim 15 , wherein the width of the seal varies continuously about the opening from a minimum width to a maximum width, the minimum and maximum widths being located diametrically opposite each other.  
     
     
         17 . The container of  claim 15 , wherein the membrane lid defines a pull-tab portion located in registration with the reduced-width portion of the seal.  
     
     
         18 . The container of  claim 15 , wherein the container body has a substantially circular cross-sectional shape.  
     
     
         19 . The container of  claim 15 , wherein the reduced-width portion of the seal is provided by virtue of the width of one portion of the flange being reduced relative to other portions of the flange.  
     
     
         20 . The container of  claim 19 , wherein the width of the flange varies continuously about the opening from a minimum width to a maximum width.  
     
     
         21 . The container of  claim 15 , wherein the reduced-width portion of the seal is provided by virtue of the sealant on the flange being applied to the flange in a variable-width pattern.  
     
     
         22 . The container of  claim 15 , wherein the flange is initially molded to have a substantially constant width all of the way around the opening, and a cut-out is formed in the flange at one circumferentially extending portion thereof so as to reduce the width of the flange at said portion, the membrane lid being sealed to the flange having the cut-out, whereby the reduced-width portion of the seal is located at said portion of the flange having the cut-out.