An injection moulded thermoplastic preform for blow moulding to form a container, the preform comprising a lower closed base portion, a hollow body portion, a hollow transition portion between the lower closed base portion and the hollow body portion, and an upper open end portion adjacent to an upper part of the hollow body portion, wherein the closed base portion comprises a central portion which extends over at least 50% of an internal radius of a lower end of the hollow body portion and is either substantially flat or has a shallow concave or convex internal curvature, and the transition portion comprises an upwardly and radially outwardly tapering portion extending away from the central portion to connect to the hollow body portion, the tapering portion being inclined at an angle of from 1 to 20 degrees to a longitudinal axis of the preform and the tapering portion increasing in thickness from the central portion to the hollow body portion. Also disclosed is a method of injection moulding the thermoplastic preform.

An injection molded thermoplastic preform for blow moulding to form a container, the preform base of a central part having a first, downwardly and radially inwardly tapering portion therebetween which increases in thickness from a radially outer end of the first tapering portion adjacent to the hollow transition portion to a radially inner end of the first tapering portion adjacent to the gate part and the middle part opposite the gate part can allow the injected resin to be urged back through the gate at the end of the injection moulding cycle at a lower fluid pressure in the vicinity of the gate which is associated with high resin temperatures. The technical effect achieved by the first tapering portion is that crystallinity in the gate area is minimized or eliminated, which avoids or minimizes partial blocking of the gate which would otherwise restrict the injected resin from being urged back through the gate at the end of the injection moulding cycle.

A preform configured to form a container by stretch blow molding. The preform includes a finish portion and a tip portion. The finish portion is at a first end of the preform and is a container finish of the container. The tip portion is at a second end of the preform opposite to the first end. The tip portion is configured to form a container base and a container heel of the container. An outer surface of the tip portion includes a flat surface, a first radius on a first side of the flat surface, a second radius between the first radius and the flat surface, a third radius extending from the flat surface on a second side of the flat surface, and a fourth radius extending from the third radius towards the second end of the preform through which a longitudinal axis of the preform extends.

A generally hollow preform for making a stretch blow-molded container may include a threaded finish portion; a neck portion depending from the finish portion; a transition portion depending from the neck portion; a main portion depending from the transition portion; and a closed, generally rounded tip portion depending from the main portion. The preform may include stretch ratios with respect to the container including an axial stretch ratio of about 3.0 to 3.5, a hoop stretch ratio of about 5.0 to 5.5, and a total stretch ratio of about 15 to 19.25. In some embodiments, high stretch ratios may be achieved with less material, yielding substantial cost savings.

A generally hollow preform for making a stretch blow-molded container may include a threaded finish portion; a neck portion depending from the finish portion; a transition portion depending from the neck portion; a main portion depending from the transition portion; and a closed, generally rounded tip portion depending from the main portion. The preform may include stretch ratios with respect to the container including an axial stretch ratio of about 3.0 to 3.5, a hoop stretch ratio of about 5.0 to 5.5, and a total stretch ratio of about 15 to 19.25. In some embodiments, high stretch ratios may be achieved with less material, yielding substantial cost savings.

An injection moulded thermoplastic preform for blow moulding to form a container, the preform comprising a lower closed base portion, a hollow body portion, a hollow transition portion between the lower closed base portion and the hollow body portion, and an upper open end portion adjacent to an upper part of the hollow body portion, wherein the closed base portion comprises a central portion which extends over at least 50% of an internal radius of a lower end of the hollow body portion and is either substantially flat or has a shallow concave or convex internal curvature, and the transition portion comprises an upwardly and radially outwardly tapering portion extending away from the central portion to connect to the hollow body portion, the tapering portion being inclined at an angle of from 1 to 20 degrees to a longitudinal axis of the preform and the tapering portion increasing in thickness from the central portion to the hollow body portion. Also disclosed is a method of injection moulding the thermoplastic preform.