Method for making a container with a unitary but removable closure

In a method for molding a container from an extruded length of a parison of semi-soft thermoplastic material in the form of a vertically oriented, elongated, hollow tube wherein said method includes the steps of:

• (A) closing about said parison a main mold means for defining cavity for subsequently forming the container body with an open top, (B) maintaining an opening at the top of the length of parison in a portion of the parison extending upwardly above the closed main mold means, (C) forming a peripheral frangible web in said parison below said top opening and also temporarily sealing the top opening of the parison, (D) molding the container by a pressure differential between the exterior of the parison in said main mold means and the interior of said parison, and (E) thereafter sealing the top of the formed container with a sealing mold, the improvement characterized in that
• step (A) includes providing in said main mold means a circumferential portion that projects inwardly into the cavity and defines a forming edge and an upwardly facing bearing surface;
• step (C) includes providing a mandrel with a downwardly facing frustoconical sealing surface and a frustoconical engaging surface extending downwardly and inwardly from said sealing surface and extending said mandrel into said parison top opening to (1) force said parison against said main mold means bearing surface with said mandrel sealing surface, and (2) sweep and squeeze said parison adjacent said main mold means forming edge with said mandrel engaging surface;
• and
• step (D) includes maintaining said mandrel at a maximum extended position in contact with said parison to (1) effect a temporary seal of said mandrel sealing surface against the parison and of the parison against said closed main mold means bearing surface during molding of the container, and (2) locate said mandrel engaging surface relative to said forming edge of the closed main mold means to retain therebetween a reduced thickness section of a parison whcih, upon subsequent retraction and upon subsequent formation of the sealed top of the container, defines a peripherl frangible web below the sealed container top.