Tamper evident lid welded to a container

Abstract

A tamper-evident plastic lid is welded to a plastic container at a welded portion and a detachable, replaceable lid portion is formed by tearing a frangible portion on the lid's skirt thereby leaving a torn tamper-evident, welded lid portion fixed to the container rim. The illustrated lid is a plug-fit lid which has a plug-shaped portion comprising a depressed central panel and an encircling, upstanding wall that engages an inner side of the container rim wall to retain the separated lid portion when it is replaced on the container. An energy director preferably in the form of an encircling bead on the lid initiates the softening of the plastic of the bead for welding with the plastic of the container rim. The preferred frangible portion is a reduced cross-sectional thickness web in a horizontally and radially extending skirt wall on the lid skirt overlying a horizontally and radially extending rim wall on the container rim. The frangible portion may be located radially inwardly of the welded portion. A pull tab may be provided on the replaceable lid portion to assist in initiating the fracturing of the thin frangible web. A pry slot may also be provided to aid in locating where and how to separate the replaceable lid portion from the welded portion which is permanently attached to the container.

1 . A tamper-evident lid for attachment to a rim of a container, the lid comprising: 
 a lid body made of plastic;    a central separable lid portion on the plastic, lid body;    a skirt on the plastic lid body for permanent attachment to the container;    a weldable portion on the skirt for being welded to the container;    a detachable, replaceable lid portion on the lid body for detachment from the skirt of the lid and for replacement on the container to cover container after the initial removal of the lid portion from the container; and    a frangible portion on the lid body between the weldable portion and the detachable lid portion for fracturing to leave the weldable portion welded to the container and to allow removal of the detachable, replaceable lid portion from the container.    
     
     
         2 . A tamper-evident lid in accordance with  claim 1  wherein the detachable, replaceable lid portion comprises: 
 a recessed central plug having a depressed central panel and an encircling, upstanding sidewall connected to the central panel.    
     
     
         3 . A tamper-evident lid in accordance with  claim 2  comprising: 
 a pull tab connected to the central plug for pulling to fracture the frangible portion and to leave the weldable portion attached to the container rim and to allow lifting of the lid portion from the container.    
     
     
         4 . A tamper-evident lid in accordance with  claim 1  wherein the weldable portion comprises: 
 an energy director in the form of a depending bead on the underside of the skirt.    
     
     
         5 . A tamper-evident lid in accordance with  claim 1  comprising: 
 a pry slot associated with the frangible portion for initiating removal of the detachable, replaceable lid portion.    
     
     
         6 . A tamper-evident lid in accordance with  claim 1  wherein the frangible portion comprises a groove forming a reduced cross-section in the skirt for fracturing.  
     
     
         7 . A tamper-evident lid in accordance with  claim 1  wherein the lid is made of injection molded plastic.  
     
     
         8 . A lid in accordance with  claim 1  wherein the tamper-evident lid is thermoformed.  
     
     
         9 . A tamper-evident lid for being welded to a rim wall on a rim of a container, the lid comprising: 
 a lid body made of plastic;    a central panel on the lid body to cover the contents of the container;    a skirt on the lid body joined to the central panel and for attachment to the rim of the container;    a substantially horizontally and radially extending skirt wall on the skirt for extending over the top of the container's rim wall;    a frangible portion on the skirt wall for fracturing to form a replaceable and detachable lid portion that includes the central panel to cover the container contents when the lid is replaced; and    a weldable portion on the skirt wall located radially outwardly of the frangible portion to be welded to the container rim wall and to remain welded thereto when the frangible portion is fractured and the replaceable lid portion is detached and removed from the container.    
     
     
         10 . A lid in accordance with  claim 9  wherein the weldable portion comprises: 
 an encircling bead formed on the underside of the horizontally and radially extending skirt wall.    
     
     
         11 . A lid in accordance with  claim 10  wherein the frangible portion comprises: 
 an annular web of reduced cross-sectional thickness in the horizontally and radially extending skirt wall.    
     
     
         12 . A lid in accordance with  claim 11  wherein the lid is a plug-fit lid having a depressed central panel joined to a higher skirt on the lid.  
     
     
         13 . A lid in accordance with  claim 9  wherein the tamper-evident lid is made by thermoforming.  
     
     
         14 . A container and tamper-evident lid comprising: 
 a plastic container having an outer and encircling rim portion surrounding an upper opening at the top of the container;    a lid body having a skirt for welding to the rim of the plastic container;    an encircling horizontal wall on the lid shirt overlying the container rim portion;    a welded portion connecting the horizontal wall to the container rim;    a frangible portion on the lid body for fracturing to provide a central replaceable lid portion with a portion of the skirt remaining welded to the container rim; and    portions interconnecting on the replaceable lid portion and the container to retain the lid portion on the container upon replacement of the lid on the container.    
     
     
         15 . A container and lid in accordance with  claim 14  wherein the frangible portion comprises a reduced, cross-sectional web in the lid skirt for tearing.  
     
     
         16 . A container and lid in accordance with  claim 14  comprising: 
 an energy director on the skirt for welding to the container rim to form the welded portion between the lid and container.    
     
     
         17 . A container and lid in accordance with  claim 14  wherein the replaceable lid comprises: 
 a depressed central panel;    an upstanding encircling wall connected to the depressed central panel; and    a horizontal flange connected to an upper end of the encircling wall and for overlying the container rim.    
     
     
         18 . A container and lid in accordance with  claim 17  wherein the lid can be reapplied by inserting it back into the container opening and pushing down on the lid.  
     
     
         19 . A container and lid in accordance with  claim 18  comprising: 
 a pry slot opening in the container rim to allow prying of the replaceable lid from the container.    
     
     
         20 . A container and tamper-evident lid comprising: 
 a plastic container having an outer and encircling rim portion surrounding an upper opening at the top of the container;    a lid body having a skirt for welding to the rim of the plastic container;    a frangible portion on the lid body for fracturing to provide a central replaceable lid portion with a portion of the skirt remaining welded to the container rim;    a horizontally and radially extending rim wall on the container for being welded to the lid skirt;    a horizontally and radially extending skirt wall disposed above the container rim wall; and    a welded portion joining the respective horizontally and radially extending rim wall and skirt wall at a location radially outwardly of the frangible portion.    
     
     
         21 . A container and lid in accordance with  claim 20  wherein the frangible portion comprises: 
 a weakened, substantially annular area in the horizontally and radially extending skirt wall.    
     
     
         22 . A container and lid in accordance with  claim 20  comprising: 
 an energy director on the horizontally and radially extending skirt wall for initially softening and welding to the container rim wall.    
     
     
         23 . A container lid in accordance with  claim 20  wherein the welded portion is formed by ultrasonic welding using the energy director.