PREFORM FOR PRODUCING PLASTIC CONTAINERS IN A STRETCH BLOW MOULDING PROCESS

摘要

A preform for producing plastic containers more particularly plastic bottles in a stretch blow moulding process is described said preform having an essentially elongated preform body (2) one longitudinal end of which has a closed design. At the opposite longitudinal end thereof the preform body adjoins a neck portion (3) provided with a pouring lip (4) on the outer wall (5) of which neck portion (3) attachment means (6) for form fit fixing of a closure part fitted with corresponding engagement means are formed. At the transition (15) from the preform body (2) to the neck portion (3) the preform (1) which has no support ring has a flange (8) that is annularly circumferential at least in sections said flange protruding radially beyond an outer wall (7) of the preform body (2). In a region between the flange (8) and the attachment means (6) a circumferential annular groove (9) is formed on the neck portion (3). The annular groove (9) is delimited by the flange (8) and in the direction of the attachment means by an outer shoulder which extends transversely from a base of the annular groove (9) to the outer wall (7) of the neck portion (3). On an inner wall (11) of the neck portion (3) the transverse outer shoulder (10) forms an inner shoulder (12) that is annularly circumferential at least in sections and extends as seen in the direction of the preform body (2) axially above the annular groove (9) and transitions into an inner wall (13) of the preform body (2) in a manner essentially free of under cuts.