Ultrasonically weldable polymeric lids and microwavable polymeric containers

Abstract

Embodiments herein relate to an ultrasonically weldable polymeric lid for a microwaveable polymeric container. In an embodiment, a lid for microwaveable containers can include a polymeric ring. The polymeric ring can define a central aperture having an inner diameter. The polymeric ring can also include a recessed shelf contacting the inner diameter of the central aperture and an ultrasonic bonding surface disposed to the outside of the recessed shelf. The lid can include a peelable film disposed on the recessed shelf and occluding the central aperture. The peelable film can be removably bonded to the recessed shelf, and can include a tab attached to an edge of the peelable film. In some cases the lid can contain substantially no metal content. Other embodiments are also included herein.

1 . A lid for microwaveable containers comprising
 a polymeric ring, the polymeric ring defining
 a central aperture having an inner diameter; 
   a recessed shelf contacting the inner diameter of the central aperture; and   an ultrasonic bonding surface disposed outside of the recessed shelf;
 a peelable film disposed on the recessed shelf and occluding the central aperture, the peelable film removably bonded to the recessed shelf; and 
   a tab attached to an edge of the peelable film;
 wherein the lid contains substantially no metal content. 
   
     
     
         2 . The lid of any of  claim 1 , wherein the lid contains less than 0.1 wt. % metal content. 
     
     
         3 . The lid of any of  claim 1 , wherein the lid contains less than 0.01 wt. % metal content. 
     
     
         4 . The lid of any of  claim 1 , wherein the lid is 100% free of metal content. 
     
     
         5 . The lid of any of  claim 1 , the peelable film comprising a peelable film. 
     
     
         6 . The lid of any of  claim 1 , the peelable film comprising a coated foil. 
     
     
         7 . The lid of any of  claim 1 , the peelable film comprising a polymeric laminated metal film. 
     
     
         8 . The lid of any of  claim 1 , wherein the lid lacks materials having an electrical conductivity of greater than 0.5×106 siemens/m. 
     
     
         9 . The lid of any of  claim 1 , wherein ultrasonic bonding surface is substantially flat. 
     
     
         10 . The lid of any of  claim 1 , further comprising an energy director bead disposed on the ultrasonic bonding surface. 
     
     
         11 . The lid of any of  claim 10 , the energy director bead comprising a hemispherical shape. 
     
     
         12 . The lid of any of  claim 10 , the energy director bead comprising a triangular shape. 
     
     
         13 . The lid of any of  claim 10 , the energy director bead comprising a height between 0.01 mm and 3 mm. 
     
     
         14 . The lid of any of  claim 1 , the polymeric ring comprising a downward pointing wall disposed to the outside of the ultrasonic bonding surface, the downward pointing wall having an inner surface and an outer surface. 
     
     
         15 . The lid of any of  claim 14 , further comprising an inward facing point disposed on an inner surface of the downward pointing wall, the inward facing point comprising a sloped bottom surface. 
     
     
         16 . The lid of any of  claim 14 , further comprising threads disposed on the outer surface of the downward pointing wall. 
     
     
         17 . The lid of any of  claim 1 , comprising an outer diameter of about 2 inches to about 5 inches. 
     
     
         18 . The lid of any of  claim 1 , wherein the peelable film is removably bonded to the recessed shelf. 
     
     
         19 . The lid of any of  claim 1 , wherein the peelable film is heat sealed to the recessed shelf. 
     
     
         20 . The lid of any of  claim 1 , wherein the peelable film is bonded to the recessed shelf with an adhesive. 
     
     
         21 . The lid of any of  claim 1 , wherein the polymeric ring comprises at least one of polycarbonates, polyvinylchloride, polyethylene, polyethylene terephthalate, polypropylene, and polyamides. 
     
     
         22 . A microwaveable food package comprising
 a cup comprising   a bottom,   a side wall, and   a top edge; and   a lid for microwaveable containers comprising   a polymeric ring, the polymeric ring defining
 a central aperture having an inner diameter; 
   a recessed shelf contacting the inner diameter of the central aperture; and   an ultrasonic bonding surface disposed outside of the recessed shelf;
 a peelable film disposed on the recessed shelf and occluding the central aperture, the peelable film removably bonded to the recessed shelf; and 
   a tab attached to an edge of the peelable film;
 wherein the lid contains substantially no metal content. 
   
     
     
         23 . The microwaveable food package of  claim 22 , the cup defining an inner volume, the food package further comprising a food material disposed within the cup.