Valve bag

Claim 1

A vented bag formed of a thermoplastic sheet material having a pair of side walls connected along their vertical edges by inwardly gusseted end walls, said side walls being heat sealed together along a generally straight line at the upper ends thereof to form a top closure for the bag, at one upper corner portion of the bag one end wall having a portion thereof folded inwardly along a line extending between the adjacent vertical edges of the two side walls and spaced downwardly from the top closure seal such that in the flattened condition of the bag the inwardly folded portion of said end wall cooperates with the portion of the end wall immediately below it to define a pair of double thickness, triangularly-shaped panels sandwiched between the adjacent portions of the side walls, said side walls being folded inwardly along lines extending diagonally inwardly and upwardly from the opposite ends of the last-mentioned fold line on the end wall to the line of sealing at said top closure, said inwardly folded end and side walls defining an opening at said corner of the bag, a tubular sleeve of thermoplastic sheet material disposed in said opening, said sleeve comprising an axially outer end portion which extends outwardly from the inner edge of the inwardly folded portion of said end wall and an axially inner portion which extends downwardly from said inner edge of the inwardly folded portion of said end wall, said tubular sleeve being connected to the inner edge of said inwardly folded portion of said end wall by a continuous heat seal, said outer end portion of said sleeve being heat sealed to said inwardly folded portion of said end wall adjacent said fold line thereon and also being heat sealed to each side wall along said diagonal fold lines, said inner end portion of said sleeve being heat sealed along said top closure and to both side walls along lines which are spaced downwardly from and generally parallel to said top seal, said last-mentioned lines of sealing extending axially inwardly of the opening from the opposite ends of the heat seal along said inner edge of the inwardly folded portion of the end wall, said heat seals along said inner edge of the inwardly folded portion of the end wall and along said parallel lines on the inner end portion of said sleeve preventing the inner end portion of the sleeve from being displaced in a direction outwardly of the opening when the bag is filled with product, said seals defining a pair of first passageways extending from inside the bag in a direction outwardly of the opening to said diagonal seals between the sleeve and each side wall and a second air passageway extending circumferentially of the opening from the outer ends of the first passageways and between the inwardly folded portion of the end wall and the axially outer end portion of said sleeve, and means providing vent holes in said second passageway to permit the escape of air therefrom to the exterior of the bag while the bag is being filled with product through a filling spout inserted into said sleeve and also after the bag is filled and the sleeve is collapsed against itself into a flattened condition by the product in the bag.