Linerless plastic closure with a sealing lip

Abstract

A cap, which can be attached to a container having an annular opening, includes a top wall and an annular skirt portion. The top wall includes an inner surface and rigid sealing members which seal an inner and outer edge of the opening through the engagement of first and second rigid members with edges of the opening and which exert a force on the container to cause the container to attach in a proper position. The annular skirt portion, disposed along an outer circumference of the top wall and extending downwards, includes internal threads configured to seal the cap onto the container, longitudinal ribs for increasing the friction on the annular skirt portion, and a pilfer band.

1 . A cap, which can be attached to a container having an annular opening, comprising: 
 a top wall comprising an inner surface including a sealing lip having first and second rigid members which, in a direction from a point between them to tops thereof, taper away from one another; and    an annular skirt portion, disposed along an outer circumference of the top wall, said annular skirt portion comprising internal threads, wherein:    the first and second rigid members are configured to provide a bidirectional centering force on the opening of the container.    
     
     
         2 . A cap according to  claim 1 , wherein a cross-section of the sealing lip comprises: 
 a first rigid member,    a second rigid member, which is symmetric with the first member about a center line therebetween.    
     
     
         3 . A cap according to  claim 1 , wherein the cap is composed of a plastic composition.  
     
     
         4 . A cap according to  claim 3 , wherein the plastic composition comprises at least one thermoplastic resin.  
     
     
         5 . A cap according to  claim 4 , wherein the thermoplastic polymer resin is selected from the group consisting of polypropylene, polyethylene, copolymers of polypropylene and polyethylene, and combinations thereof.  
     
     
         6 . A cap according to  claim 5 , wherein the polyethylene is selected from the group consisting of linear polyethylene, high density polyethylene, and low density polyethylene, and combinations thereof.  
     
     
         7 . A cap, which can be attached to a container having an annular opening, comprising: 
 a top wall comprising an inner surface including a sealing lip having first and second rigid members of substantially equal rigidity, which, in a direction from a point between them to tops thereof, taper away from one another; and    an annular skirt portion, disposed along an outer circumference of the top wall, said annular skirt portion comprising internal threads.    
     
     
         8 . A cap according to  claim 7 , wherein a cross-section of the sealing lip comprises: 
 a first rigid member,    a second rigid member, which is symmetric with the first member about a center line therebetween.    
     
     
         9 . A cap according to  claim 7 , wherein the cap is composed of a plastic composition.  
     
     
         10 . A cap according to  claim 9 , wherein the plastic composition comprises at least one thermoplastic resin.  
     
     
         11 . A cap according to  claim 10 , wherein the thermoplastic polymer resin is selected from the group consisting of polypropylene, copolymers of polypropylene and polyethylene, and combinations thereof.  
     
     
         12 . A cap according to  claim 11 , wherein the polyethylene is selected from the group consisting of linear polyethylene, high density polyethylene, and low density polyethylene, and combinations thereof.  
     
     
         13 . A cap, which can be removably attached to a container having an annular opening, comprising: 
 a top wall comprising an inner surface including a sealing lip having first and second rigid members which, in a direction from a point between them to tops thereof, taper away from one another; and    an annular skirt portion, disposed along an outer circumference of the top wall, said annular skirt portion comprising internal threads, and    a means on the top wall for providing a bidirectional centering force on the opening of the container.