Sealing closure for a flexible container

A closable and re-openable flexible container capable of forming a liquid and vapor tight seal, comprising:

• a bag-like container formed of flexible film material, closed at a bottom edge and two side edges and open at a top comprising two top edges;
• a pair of sealing lips bonded to the top edges of the container, continuous along the edges, the lips being formed of resilient material and being preformed in an outwardly bowed configuration to normally resiliently bow outwardly to hold the container top open, for aiding in putting material into the container, one of the sealing lips having an inside surface with at least one raised ridge continuous through the length of the lip, the opposite lip having a generally flat mating inside surface free of recesses to avoid contamination by substances stored in the container, the raised ridge being positioned to be compressed against and depressed into the opposite flat lip surface when the closure strip is advanced toward the closed position, to provide a better seal;
• a slidable, generally channel-shaped, relatively rigid closure strip having a pair of depending flanges spaced apart and positioned to compress the resilient lips together along their full length when the closure strip is advanced longitudinally over the lips, the flanges being shaped generally complementarily to the exterior of the lips for gripping retention thereon, and the closure strip including a handle portion extending from one end;
• and
• a grip comprising a pull tab formed integrally with the sealing lips and extending from one end thereof, for enabling a user to pull the sealing lips slideably into the closure strip.