Coinjection hot runner injection molding system

A coinjection molding apparatus comprising:

• an injection molding nozzle having a nozzle body with a longitudinal bore extending there through;
• a tubular sleeve disposed to extend within the nozzle bore to divide the nozzle bore into a skin material melt channel for carrying a skin material melt stream and a core material melt channel for carrying a core material melt stream, wherein the skin material melt channel is defined by an inner surface of the sleeve and the core material melt channel is defined between an outer surface of the sleeve and the nozzle bore;
• a nozzle tip coupled to the nozzle body having
• a tip divider that defines a central skin material melt passage for receiving the skin material melt stream from the skin material melt channel of the nozzle, the tip divider having a central opening through a downstream end thereof that is axially aligned with a mold gate, and
• a tip cap having at least a portion of an inner surface thereof that is spaced from an outer surface of the tip divider to define at least a portion of a core material melt passage therebetween for receiving the core material melt stream from the core material melt channel of the nozzle, the tip cap having a central opening through a downstream end thereof that is axially aligned with the tip divider central opening and the mold gate,
• a tip retainer for securing the nozzle tip to a downstream end of the nozzle body, the tip retainer having an inner surface that is spaced from an outer surface of the tip cap to define an outer layer melt passage therebetween for receiving a portion of the skin material melt stream from the central skin material melt passage;
• and
• a valve pin slidably disposed through the nozzle and the nozzle tip, wherein the valve pin extends through the central openings of the tip divider and tip cap, respectively, to permit a downstream end of the valve pin to be seatable within the mold gate,
• wherein when the valve pin is fully retracted relative to the central openings of the tip divider and tip cap, respective melt streams from the central skin material melt passage, the core material melt passage and the outer layer melt passage flow toward the mold gate and are combined downstream of the nozzle tip prior to entering the mold gate.