Patent ID: 8360275

Claim:
A method for sealing a plastic spout between two foil walls of a pouch, wherein the spout comprises an injection moulded single part spout body comprising: (a) a transverse wall; (b) thin, flexible sealing walls that each have an upper edge adjoining the transverse wall and that project perpendicularly downwards from said transverse wall, said flexible sealing walls between them delimit an oval space having essentially the same cross-section over its length, the dimension of the transverse wall exceeding that of the cross-section of the oval space, and said flexible sealing walls each have a curvature over their entire length as viewed from below the spout, such that each sealing wall is outwardly convex over its entire length with respect to an imaginary plane passing through the outermost ends, which adjoin one another, of the sealing walls; (c) thin lips, each formed at the location where the outermost ends of the sealing walls meet and projecting outwardly in said imaginary plane, and (d) an upwardly projecting cylindrical tubular part adjoining at its lower end the transverse wall, said tubular part projecting perpendicularly upwards from said transverse wall, the cross-section of the oval space exceeding that of the cross-section of the cylindrical tubular part, said tubular part forming at least a part of a passage that extends through the transverse wall and is in communication with said oval space for delivering a medium from the pouch or feeding a medium to the pouch, said tubular part including screw thread, wherein the sealing method comprises the step of pressing the foil walls onto the sealing walls using heated pressure-exerting jaws without a support member internally supporting the sealing walls, the pressure-exerting jaws completely surrounding the sealing walls and the curvature of the sealing walls over their entire length providing resistance against the sealing walls being undesirably folded inwards, so that a sufficient pressure is obtained between the foil walls and the internally unsupported sealing walls, the thin lips forming a transition to the parts of the foil walls of the pouch which are sealed directly together.