When a hollow molded body using a preform to be molded with a thin bottom portion is produced while taking advantage of the roughening of the outer surface of an injection core mold, transferred roughening marks are prevented from appearing on the bottom portion of hollow molded bodies, so that the hollow molded body with an aesthetic bottom portion is obtained. An injection core mold (12) has an outer surface of its tip portion corresponding to a preform bottom portion (10) and a lower end portion (14a) of a preform body portion (14). The outer surface corresponding to the preform bottom portion (10) and the lower end portion (14a) of the preform body portion (14) is a mirror-finished surface (20), and the outer surface of the injection core mold for forming the preform other than the mirror-finished surface is a roughened surface (15).

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.

The invention relates to a new PET preform design that enables a more precise distribution of material in the bottle bottom and avoids the waste of material around the injection point. The thickness BWT.sub.min of the wall at the center of the gate or tip (3) (injection point) is reduced to a minimum in order to avoid the waste of material around the injection point when the preform is blown. This is particular important for carbonated soft drink application since the reduced amount of amorphous material at the center of the gate (3) helps to reduce the risk of stress cracking on the bottle base. Furthermore a step (4) having thickness WT.sub.max in the body wall thickness, in the region of the periphery of the base with WT.sub.max>WT, allows enough material to be available for the proper blowing of the bottle bottom making the bottle more stable.

Disclosed is a preform for a plastics container, which includes: a rotationally symmetrical body about a central axis; an open neck which extends in continuation of the body from an upper end of the latter; a bottom which closes the body starting from a lower end of the latter, the bottom being rotationally symmetrical about the central axis and having a central concavity and a protruding bulge around this concavity, the bottom having a thickness E, measured from an external face, that is variable in accordance with three different criteria respectively applied to three sections of the bottom, namely a central section [0; S.sub.1], an intermediate section [S.sub.1; S.sub.2] and a peripheral section [S.sub.2; L].

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.

A forming mold is used when forming a preform, which has a neck portion and a barrel portion, and whose barrel portion is filled with a molding material over the entire axial direction thereof, by injection molding; forming a space part in the barrel portion of the preform to convert the preform into an intermediate molded product; and blow-molding the intermediate molded product to form a hollow container which is a final molded product. The forming mold is equipped with a boring rod which is inserted from the neck portion side into the barrel portion of the preform to form the space part of at least a predetermined depth in the barrel portion.

The present disclosure relates to an aerosol container made of plastic, the container having a neck, the opening of which is closeable in a pressure-tight manner by a valve unit that can be actuated by a pushbutton, the container being Tillable with a liquid or gaseous propellant and a liquid to be sprayed. The aerosol container can be an injection cast preform with an elongated tubular preform body. The preform body is closed by a dome-shaped convex preform base, beyond which an integrally formed stand region projects in an axial direction. The preform body adjoins the opening of the neck at the opposite axial longitudinal ends of the preform body.

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.

The present application includes an injection molding step and a stretch blow molding step. The stretch blow molding step is configured to include: a first step in which preliminary blow air is introduced into a preform to stretch the preform in a state in which a stretching rod does not contact the bottom of the preform; a second step which is executed after the first step, and in which the preliminary blow air is introduced into the preform and the stretching rod is moved at a set speed and pressed against the bottom of the preform to stretch the preform; and a third step which is executed after the second step, and in which final blow air is introduced into the preform to stretch the preform.

A forming mold is used when forming a preform, which has a neck portion and a barrel portion, and whose barrel portion is filled with a molding material over the entire axial direction thereof, by injection molding; forming a space part in the barrel portion of the preform to convert the preform into an intermediate molded product; and blow-molding the intermediate molded product to form a hollow container which is a final molded product. The forming mold is equipped with a boring rod which is inserted from the neck portion side into the barrel portion of the preform to form the space part of at least a predetermined depth in the barrel portion.