A method of injection molding a test tube-shaped preform for biaxial stretch blow molding includes supplying a major material resin from outer and inner flow paths to a combined flow path for a predetermined time and rate. For a period of time within a range of the predetermined time period during which the major material resin is supplied, the intermediate layer resin is simultaneously supplied from the middle flow path to the combined flow path at a second predetermined supplying rate. A columnar laminated molten resin is injected into a cavity of a metal mold connected to a tip of the nozzle through a gate to fill the cavity, the columnar laminated molten resin being composed of the major material resin and the intermediate layer resin formed in the major material resin in a laminated manner that are combined into a columnar shape at the combined flow path.

A method of injection molding a test tube-shaped preform for biaxial stretch blow molding includes supplying a major material resin from outer and inner flow paths to a combined flow path for a predetermined time and rate. For a period of time within a range of the predetermined time period during which the major material resin is supplied, the intermediate layer resin is simultaneously supplied from the middle flow path to the combined flow path at a second predetermined supplying rate. A columnar laminated molten resin is injected into a cavity of a metal mold connected to a tip of the nozzle through a gate to fill the cavity, the columnar laminated molten resin being composed of the major material resin and the intermediate layer resin formed in the major material resin in a laminated manner that are combined into a columnar shape at the combined flow path.

A method of injection molding a test tube-shaped preform for biaxial stretch blow molding includes supplying a major material resin from outer and inner flow paths to a combined flow path for a predetermined time and rate. For a period of time within a range of the predetermined time period during which the major material resin is supplied, the intermediate layer resin is simultaneously supplied from the middle flow path to the combined flow path at a second predetermined supplying rate. A columnar laminated molten resin is injected into a cavity of a metal mold connected to a tip of the nozzle through a gate to fill the cavity, the columnar laminated molten resin being composed of the major material resin and the intermediate layer resin formed in the major material resin in a laminated manner that are combined into a columnar shape at the combined flow path.

A co-injection nozzle is disclosed that includes a combining means configured to reduce shear heating and create a more even shear heating profile in core and skin material flow streams. The combining means is configured to reduce shear heating peaks and valleys in core and skin material flow streams as the streams flow between annular channels of the combining means during a mold filling process.

A resin molding method includes a first molding step of molding a first molded part and a second molded part in a mold and a second molding step of joining the first molded part and the second molded part. In the first molding step, the second molded part is formed by injecting resin into an area where a first core movable in the first direction and a second core movable in a second direction are engaged. In the second molding step, the second molded part is joined to the first molded part by injecting the resin while the first core is in contact with the second molded part and the second core is removed from the second molded part. Areas where the first core and the second core are located in the first molding step become hollow areas connected to each other and part of ends of the first core in the first direction is not in contact with the second core.

A co-injection nozzle is disclosed that includes a combining means configured to reduce shear heating and create a more even shear heating profile in core and skin material flow streams. The combining means is configured to reduce shear heating peaks and valleys in core and skin material flow streams as the streams flow between annular channels of the combining means during a mold filling process.

Methods and systems for co-extruding multiple polymeric material flow streams into a mold having a plurality of cavities to produce a plurality of multi-layer polymeric articles each having a consistent coverage of an interior core layer are disclosed herein. In an example method, a flow rate of a first skin material into a cavity is individually controlled for each cavity before initiation of co-injection of a second core material into the cavity, which may address inconsistent interior core layer coverage for articles from different cavities.

Methods and systems for co-extruding multiple polymeric material flow streams into a mold having a plurality of cavities to produce a plurality of multi-layer polymeric articles each having a consistent coverage of an interior core layer are disclosed herein. In an example method, a flow rate of a first skin material into a cavity is individually controlled for each cavity before initiation of co-injection of a second core material into the cavity, which may address inconsistent interior core layer coverage for articles from different cavities.

An injection molding device including a middle flow channel which forms an intermediate layer of a preform which is subject to biaxial stretch blow molding. The middle flow channel s segmented into a predetermined number of flow sub-channels by vertical blocking rib piece(s). Side wall's upstream portions of the vertical blocking rib piece are formed as angled surfaces whose distance from each other decreases from the downstream side to the upstream side, and/or, an end portion of the vertical blocking rib piece that is located on the downstream side is tucked in at least one of the inner flow channel and the outer flow channel.

Methods and systems for co-extruding multiple polymeric material flow streams into a mold having a plurality of cavities to produce a plurality of multi-layer polymeric articles each having a consistent coverage of an interior core layer are disclosed herein. In an example method, a flow rate of a first skin material into a cavity is individually controlled for each cavity before initiation of co-injection of a second core material into the cavity, which may address inconsistent interior core layer coverage for articles from different cavities.