An apparatus for injection molding a plurality of multilayer, multimaterial plastic containers. A plurality of co-injection nozzles are positioned to feed a plurality of cavities defined by a plurality of injection molds and a source of polymer materials is located upstream of the nozzles. The apparatus also includes a flow channel for each of a plurality of polymer streams to define a path between the polymer source and at least one of the co-injection nozzles such that each of the co-injection nozzles is in communication with one of the flow channels for each polymer stream and the polymer streams enter more than one of the co-injection nozzles. The channels are arranged to provide substantially the same flow experience to each polymer stream.
This application is a continuation of application Ser. No. 08/341,700 filed Nov. 18, 1994, now U.S. Pat. No. 5,523,045, which is a continuation of application Ser. No. 07/740,749 filed Aug. 5, 1991, now abandoned, which is a continuation of application Ser. No. 07/563,169 filed Aug. 3, 1990, now U.S. Pat. No. 5,037,285, which is a continuation of application Ser. No. 07/397,348 filed Aug. 22, 1989, now U.S. Pat. No. 4,946,365 which is a continuation of application Ser. No. 07/283,000 filed Dec. 2, 1988, now abandoned, which is a continuation of application Ser. No. 06/909,941, filed Sep. 19, 1986, now abandoned, which is a division of application Ser. No. 06/484,707, filed Apr. 13, 1983, now U.S. Pat. No. 4,712,990.
Foamed molded articles can be produced during an injection molding process, among other things, by utilizing physical blowing agents. Existing technologies differ to the greatest possible extent in the manner how the blowing agent is introduced into the melt. One possibility is to supply the blowing agent via mixing elements (9) from porous or permeable material that are provided across the screw piston (1) and which by means of a suitable blowing agent input unit load and homogeneously charge the melt with blowing agent during the metering phase of the polymeric material. The resulting single phase polymer/blowing agent mixture, when injected in to an injection mold tool, produces due to a reduction in pressure, a foam-textured part.
A co-injection nozzle pin (20) having downstream and upstream ends. The nozzle pin has therein a central bore (30) including an upstream end (32) adapted to communicate with a first material and a downstream end (34) exiting at the downstream end of the pin. The nozzle pin also has an outer surface (36) including a first portion (38) having a diameter D.sub.1, a second portion (40) having a diameter D.sub.2, wherein D.sub.2 is less than D.sub.1 and the first portion is rearward of the second portion. The pin further includes a channel (46) spiralling around the outer surface and being adapted to communicate with a second material. The channel (46) includes a first segment (52) defined in the first portion (38) of the outer surface and increasing in depth as it travels in a downstream direction and a second segment (54) defined in the second portion (40) of the outer surface and decreasing in depth as it travels in a downstream direction.
A die tip adapted for extruding a plurality of meltblown multicomponent filaments that includes at least two series of conduits that extend and converge in to the interior of the die tip to convey a multicomponent thermoplastic structure in to the interior of the die tip to a series of capillaries that extend to a series of die opening for extruding multicomponent filaments is provided.
The invention provides a method of co-injection molding. The method includes mixing a plastic inner material and an endothermic-blowing agent to form a core mixture. A plastic outer material is injected from a first injection unit into a co-injection manifold to create a flow of outer material therethrough. The core mixture is injected from a second injection unit into the co-injection manifold to create a flow of core mixture therethrough. The flow of the outer material and the flow of the core mixture are then controlled through the co-injection manifold and into a mold cavity. The core mixture expands as heat is provided for the endothermic-blowing agent to absorb.
