Reenforced bags

Claim 1

A BAG, INCLUDING A SHEET OF THERMOPLASTIC FILM MATERIAL FOLDED ON ITSELF TO PROVIDE FRONT AND BACK PANELS AND HAVING AN OPEN END SPACED FROM THE PANEL-PROVIDING FOLD LINE, SAID FRONT AND BACK PANELS EACH HAVING FIRST AND SECOND EDGE PORTIONS EXTENDING TRANSVERSELY OF THE PANELPROVIDING FOLD LINE, MEANS SEALING SAID FIRST AND SECOND EDGE PORTIONS OF SAID FRONT AND BACK PANELS TOGETHER TO FORM AN ENVELOPE OPEN AT THE FOURTH SIDE, THE ENVELOPEDEFINING BONDS ADJACENT SAID FOURTH SIDE TERMINATING SHORT OF SAID FOURTH SIDE TO PROVIDE END FLAPS ON SAID FRONT AND BACK PANELS, A PAPER STRIP HAVING FIRST AND SECOND SIDES COATED WITH THERMOPLASTIC FILM MATERIAL HEAT BONDABLE TO THE FIRST-NAMED FILM MATERIAL AND POSITIONED IN SAID OPEN END OF SAID ENVELOPE, SAID STRIP HAVING A DIMENSION PARALLEL TO SAID FOLD LINE SUBSTANTIALLY EQUAL TO THE DISTANCE BETWEEN THE FIRST AND SECOND EDGES OF EACH OF SAID PANELS AND A DIMENSION PERPENDICULAR TO SAID FOLD LINE GREATER THAN THE FLAP DIMENSION PERPENDICULAR TO SAID FOLD LINE, SAID STRIP EXTENDING BUT PART WAY INTO THE ENVELOPE, SAID PAPER STRIP BEING HEAT BONDED TO ONLY ONE OF SAID END FLAPS, AND SAID OTHER FLAP AT THE OPPOSED UNBONDED ENDS THEREOF DEFINING SLITS FACILITATING THE UNFOLDING OF SAID OTHER FLAP TO PROVIDE ACCESS TO THE ENVELOPE WITH THE BONDS ADJACENT SAID FOURTH SIDE OPPOSING THE TENDENCY OF THE SLITS TO ENLARGE.