Abstract: A multi-coinjection nozzle injection molding machine and nozzle for co-injecting at least three streams of melt materials to form a multi-layer article. The nozzle includes at least two interfitting shells and a nozzle cap. At least one of the shells has a feed flow channel for flow of melt material which leads to an associated annular flow passageway. The shells have a symmetrical furstoconical shape and and form a fixed tapered, symmetrical, frustoconical portion of an annular passageway which terminates at a fixed, annular orifice for the flow of melt material therethrough.

Abstract: A method of forming multi-layer plastic articles by using a multi-cavity injection molding machine. A combined material stream is injected from a plurality of co-injection nozzles into associated injection cavities. Streams of polymeric materials which form the layers of the articles are directed separately into each of the nozzles and in each of the nozzles a combines stream is formed which is injected into the cavities. The individual flow of each of the material streams in the nozzle can be controlled in the nozzle.

Abstract: Methods of injecting into a cavity an at least three-layer flow stream having a fast flow stream line, are provided which include establishing the flow of material of first and second layers of the flow stream to form an interface therebetween at a first location not coincident with the fast flow stream line, interposing the flow of material of a third layer in the interface, and moving the third layer to a second location relatively more proximate to, substantially coincident with, or across from and not substantially coincident with the fast flow stream line. This moving achieves foldover of the third layer and can be effected by selectively changing the flow of material(s) on one side of the third layer relative to the flow of material(s) on the other side thereof, at or shortly after the interposition of the third layer. Preferably, the interface is annular and the interposition is at substantially all places around the interface.

Abstract: Injection molded and injection blow molded multi-layer substantially rigid plastic articles are provided, which, in preferred embodiments, include:at least five layer plastic articles having side and bottom walls comprised of an outside surface layer, an inside surface layer, an internal layer, and first and second intermediate layers, one on either side of the internal layer, and having the terminal end of the internal layer encapsulated by intermediate layer material, whether it be solely or primarily by first or by both first and second intermediate layer material.

Abstract: Apparatus for unit cavity and multi-cavity, multi-layer injection molding and injection blow-molding machines are provided, which in preferred embodiments, include one or more co-injection nozzle means each having a central channel, at least two passageways having associated orifices which communicate with the central channel and valve means operative in the central channel and movable to block and unblock the orifices. The valve means preferably comprise an elongated sleeve having an axial central passageway and a port in its side wall and an elongated pin axially-reciprocable within the sleeve central passageway. The sleeve and pin are mounted in close tolerance slip fit relationship to prevent significant accumulation of polymer melt material therebetween.

Abstract: Injection molded and injection blow molded multi-layer plastic articles, parisons and containers are provided, which, in preferred embodiments are substantially rigid and have at least three layers wherein a portion of the marginal end portion of their internal layer is folded over within the marginal end portion of the side wall of the article, preferably in the flange if the article is a parison or container. The articles folded over portion can be toward the inside or the outside of the side wall. The articles, parison, and containers can be open-ended, or closed, for example, with end closures double seamed thereto or flexible lids secured thereto by an adherent, or heat seal, or other suitable means. The folded over portion and any not folded over portion of the internal layer preferably extends substantially uniformly into the marginal end portion of the side wall.

Abstract: A device for use with a runner block and a multi-polymer co-injection nozzle having separate rear entrance ports for separate polymer streams, in a multi-coinjection nozzle, multi-polymer injection molding machine, for receiving from the runner block a plurality of separate polymer flow streams and for redirecting them to flow axially out of the forward end of the device into the nozzle rear entrance ports. The device has inlets cut radially into its periphery, each for receiving a polymer flow stream, and has feed channels, each in communication with an inlet and having an inward portion cut toward the device's central axis, and an axial portion communicating with the inward portion, running axially forward and terminating at an exit hole in the device's forward end, the exit holes being in a spaced pattern for feeding the separate polymer flow streams in spaced relation into the nozzle rear entrance ports.

Abstract: Apparatus for unit cavity and multi-cavity, multi-layer injection molding and injection blow molding machines are provided, which, in preferred embodiments, include:Coinjection nozzle means, each for plural polymers, valve means for each nozzle, the valve means being adapted to move through a nozzle central channel to clear the nozzle channel of melt, a feed-block for each nozzle, polymer melt splitters, drive means for each valve means, a free floating runner system and a force compensation system to provide an effective pressure seal between the nozzles and the cavity block.