Closure construction for containers

Claim 1

IN A CONTAINER FORMED OF FOLDABLE SHEET SHOCK COATED ON ONE SIDE WITH A THERMOPLASTIC FILM, SAID CONTAINER HAVING FOUR SIDE WALL BEARING SAID FILM ON THEIR INNER FACES, AN END CLOSURE FOR SAID CONTAINER COMPRISING A REVERSELY FOLDED ELEMENT INTEGRAL WITH EACH OF TWO OPPOSED SIDE WALLS OF THE CONTAINER, SAID ELEMENT BEING FOLDABLE ALONG THE UPPER EDGE OF ITS RESPECTIVE SIDE WALL INTO A PLANE TRANSVERSE TO SAID SIDE WALL, THE UPPER FACE OF SAID ELEMENT BEARING SAID THERMOPLASTIC COATING, A COVER PANEL INTEGRAL WITH A THIRD SIDE WALL OF SAID CONTAINER BETWEEN SAID OPPOSED SIDE WALL, SAID COVER PANEL BEING FOLDABLE ALONG THE UPPER EDGE OF SAID THIRD SIDE WALL INTO SUPERPOSED RELATIONSHIP WITH SAID ELEMENTS, THE UNDER FACE OF SAID COVER PANEL BEARING SAID THERMOPLASTIC COATING, AND A COATING OF NON-THERMOPLASTIC MATERIAL BETWEEN EACH OF SAID ELEMENTS AND SAID COVER PANEL, SAID NONTHERMOPLASTIC COATING BEING ARRANGED IN A PATTERN SUCH THAT IN A CONTINUOUS REGION EXTENDING FOR THE FULL LENGTH OF EACH OF SAID ELEMENTS THE THERMOPLASTIC FILM ON THE UPPER FACE OF SAID ELEMENT IS EXPOSED TO THE THERMOPLASTIC FILM ON THE UNDER FACE OF SAID COVER PANEL, WHEREBY UPON APPLICATION OF HEAT AND PRESSURE TO SAID SUPERPOSED COVER PANEL AND ELEMENTS A FIRM BOND IS ESTABLISHED IN SAID CONTINUOUS REGIONS AND A READILY SEPARABLE COHERED SEAM IS ESTABLISHED IN THE REGIONS OCCUPIED BY SAID NON-THERMOPLASTIC COATING.