The thermal bag (2) is made of thermally insulating composite material folded to form a bottom and welded along lateral borders (3) to form a body (1) of the bag with a mouth (5) at the level of which a handle (7A, 7B) is applied. The composite material defines a bottom folded in an accordion-like fashion opposite the mouth of the bag, and a laminar stiffening element (15) of the accordion-like bottom is disposed inside the bag.

An apparatus for producing a filmic packaging material having a continuously folded portion includes a first component having a protruding part; a first roller rollable on its longitudinal axis, the first roller provided with a recess on its outer surface for receiving the protruding part; a drive mechanism for moving the material along a path in a manner such that a continuous portion of the material is drawn into the recess of the first roller by the protruding part of the first component such that the continuous portion of the material is folded, forming a continuously folded portion having an overlapping surface due to the arrangement of the protruding part of the first component in relation to the recess of the first roller; a bonding component provided downstream of the first roller arranged to adhere together the overlapping surface of the continuously folded portion of the material.

An apparatus for producing a filmic packaging material having a continuously folded portion includes a first component having a protruding part; a first roller rollable on its longitudinal axis, the first roller provided with a recess on its outer surface for receiving the protruding part; a drive mechanism for moving the material along a path in a manner such that a continuous portion of the material is drawn into the recess of the first roller by the protruding part of the first component such that the continuous portion of the material is folded, forming a continuously folded portion having an overlapping surface due to the arrangement of the protruding part of the first component in relation to the recess of the first roller; a bonding component provided downstream of the first roller arranged to adhere together the overlapping surface of the continuously folded portion of the material.

A film bag has a pair of longitudinally extending film face panels having longitudinal edges and first and second folded film gussets having longitudinal edges welded at longitudinal seams to respective longitudinal edges of the face panels and formed with two spaced throughgoing cuts forming a handle loop. A separate film inner liner panel lies against an inner face of the first gusset, extends a full transverse width of the first gusset, and is fixed at the longitudinal welds of the first gusset to the front panels so that the liner prevents leakage from the bag through the cuts.