Polypropylene preform for producing bottles or the like by blow molding or stretch-blow molding and method of blowing or stretch-blow molding of the preform

The invention refers to the manufacture of containers (2) with narrow neck and elongate body (such as bottles or the like) in polypropylene by blow molding or stretch blow molding; it is expected that the preform (1) polypropylene support, during the step of blowing or stretch-blow molding, a longitudinal stretching in a ratio (L / W) of between about 2 and 3.5 and a radial extension (D / d) in a ratio of between about 2 and 3.