Container of plastic material and method of producing same

Claim 1

A GENERALLY FLAT SELF-SUPPORTING POUCH TYPE CONTAINER COMPRISING A PAIR OF OPPOSITE FLAT SIDE WALLS OF BENDABLE YET RELATIVELY STIFF MATERIAL, A GUSSET CONSTRUCTION ALONG ONE MARGIN OF SAID CONTAINER INTERPOSED AND NORMALLY FOLDED INWARDLY BETWEEN SAID SIDE WALLS, SAID SIDE WALLS ALONG OTHER MARGINS OF SAID CONTAINER BEING SEALED TO EACH OTHER IN FACE-TO-FACE RELATIONSHIP CLOSELY ADJACENT SAID OTHER MARGINS TO PROVIDE SUCH POUCH WITH FLAT FIN-TYPE SEAMS AND WITH A PRODUCT-CONTAINING AREA EXTENDING SUBSTANTIALLY THE FULL EXTENT OF SAID SIDE WALLS BETWEEN SAID OTHER MARGINS; SAID GUSSET CONSTRUCTION COMPRISING A FLEXIBLE GUSSET PANEL SECURED TO MARGINAL PORTIONS OF SAID SIDE WALLS AND BEING FOLDED INWARDLY THEREBETWEEN, SAID FLEXIBLE GUSSET PANEL BEING JOINED WITH SAID SIDE-WALL MARGINAL PORTIONS ALONG NON-STRAIGHT SEAL LINES REMOVED FROM SAID ONE MARGIN WHICH TOGETHER DEFINE A NON-RECTANGULAR STRESS-DISTRIBUTING GENERALLY ELLIPTICAL UNSEALED AREA INWARDLY OF SAID SEAL LINES WHEN SAID GUSSET IS EXPANDED.