Process for the production of a blank for subsequent shaping by blow-molding

A process for the manufacture of a tubular pre-moulding from a thermoplastic material comprising the steps of axially stretching a tube of the thermoplastic material to a substantially reduced material thickness in at least a central zone of a tube while substantially maintaining the diameter of the tube in the axially stretched section in said central zone, the reduction being by a factor sufficient to cause yielding and orienting of the material substantially in the axial direction of the future pre-moulding, the axial stretching of the tube being effected at a temperature not greater than the glass transition temperature of the thermoplastic material, heating the material in one of the oriented zones to a temperature above the glass transition temperature and expanding said material in the radial direction of the tube until it makes contact with mould walls to form a mouth part with adjacent neck sections of the pre-moulding, cooling the material to a temperature below the glass transition temperature, heating the material in at least one end of the tube to a temperature above the glass transition temperature, and reshaping said end to form the closure of the pre-moulding.