Thin-walled containers and thin-walled closures for containers

Claim 1

A THIN-WALLED CONTAINER MEANS MADE OF RESILIENT PLASTIC SHEET MATERIAL, INCLUDING A THIN-WALLED TUBULAR PART HAVING A SCREWTHREAD OF "REVERSE BUTTRESS" TYPE FORMED THEREON BY DEFORMATION OF THE MATERIAL WITHOUT SUBSTANTIAL CHANGE IN ITS THICKNESS, THE TUBULAR PART ON WHICH THE SCREWTHREAD IS FORMED BEING OF MEAN TAPERED FORM AND WITH THE NARROW FLANK OF THE REVERSE BUTTRESS THREAD FACING TOWARDS THE SMALLER END OF THE TUBULAR PART, WHILE THE ANGLE OF THE MEAN TAPER IS SUCH IN RELATION TO THE AXIAL LENGTH OF THE WIDER FLANK OF THE REVERSE BUTTRESS THREAD, THE ANGLE WHICH THIS WIDER FLANK MAKES WITH THE AXIS OF THE TUBULAR PART AND THE MEAN TAPER OF SUCH TUBULAR PART THAT, IN CROSS-SECTIONS CONTAINING THE AXIS OF THE TUBULAR PART, WHEREAS THE WIDER FLANK OF THE THREAD IS INCLINED AT A SMALL ANGLE TO THE SAID AXIS IN ONE SENSE, THE LINE REPRESENTING THE MEAN TAPER ON THE TUBULAR PART IS INCLINED AT A SLIGHTLY LARGER ANGLE TO THE SAID AXIS IN THE OPPOSITE SENSE AND SO THAT, AS REGARDS ANY TWO ADJACENT CONVOLUTIONS OF THE THREAD, THE CROWN OF THE CONVOLUTION LYING NEARER THE SMALLER END OF THE TUBULAR PART LIES NEARER TO SAID AXIS THAN THE ROOT OF THE CONVOLUTION LYING NEARER THE LARGER END OF THE TUBULAR PART.