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    Methods and apparatus for injection molding and injection blow molding multi-layer plastic and the articles made thereby
    5.
    发明授权
    Methods and apparatus for injection molding and injection blow molding multi-layer plastic and the articles made thereby 失效

    公开(公告)号：US06129960A

    公开(公告)日：2000-10-10

    申请号：US268873

    申请日：1999-03-16

    申请人： Frederick G. Kudert ,  Maurice G. Latreille ,  Robert J. McHenry ,  George F. Nahill ,  Henry Pfutzenreuter, III ,  William A. Tennant ,  Thomas T. Tung ,  John Vella, Jr.

    发明人： Frederick G. Kudert ,  Maurice G. Latreille ,  Robert J. McHenry ,  George F. Nahill ,  Henry Pfutzenreuter, III ,  William A. Tennant ,  Thomas T. Tung ,  John Vella, Jr.

    IPC分类号： B29C45/16 ,  B29C49/22 ,  B65D1/28 ,  B65D81/26 ,  B29D23/00 ,  B65D1/40

    CPC分类号： B29C47/061 ,  B29C45/1607 ,  B29C45/1643 ,  B29C49/22 ,  B65D1/28 ,  B65D81/266 ,  B29B2911/14053 ,  B29B2911/14066 ,  B29B2911/1408 ,  B29B2911/14093 ,  B29B2911/1412 ,  B29B2911/14126 ,  B29C2045/161 ,  B29C2045/1612 ,  B29C47/0019 ,  B29C47/0023 ,  B29K2105/26 ,  B29L2031/716 ,  Y10T428/1352 ,  Y10T428/1379 ,  Y10T428/1383 ,  Y10T428/139 ,  Y10T428/1393

    摘要： Apparatus for unit cavity and multi-cavity, multi-layer injection molding and injection blow molding machines are provided, which in preferred embodiments, include:co-injection nozzle means including multi-polymer co-injection nozzles comprising an assembly of shells, and having fixed, tapered passageways communicating with annular orifices close to the nozzle gate and to each other, and polymer flow balancing and directing means in the passageways in the form of concentric and eccentric chokes;valve means for each co-injection nozzle, operative in the nozzle central channel to and adapted to be moved to different positions to block and unblock the nozzle orifices, and, in each nozzle to controls the initiation, flow and termination of flow of a plurality of polymer flow streams, comprised of an elongated sleeve having an axial central passageway and a port in its side wall and axially-reciprocable within the nozzle central channel, and, either a solid pin within and fixed relative to the sleeve, or, more preferably, an elongated pin axially-reciprocable within the sleeve central passageway, the sleeves and pins each mounted in close tolerance slip fits to prevent any significant accumulation of polymer melt material therebetween;valve means adapted to move through a nozzle central channel to assist in knitting the internal layer with itself in the central channel;valve means adapted to move through a nozzle central channel with an accumulation of polymer melt material at its forward end, and to assist in encapsulating the knit internal layer in what will be the sprue or bottom area of the container to be formed;valve means adapted to be moved through a nozzle central channel to substantially clear the central channel of polymer melt material;a feed block for each co-injection nozzle, for receiving a plurality of separate polymer melt material flow streams in an axially-aligned, spaced pattern in the periphery of the device, and for redirecting their travel paths to flow axially in a radially-spaced pattern out of the forward end of the device into the rear of a co-injection nozzle;polymer melt material flow stream splitter devices, including runner extensions, T-splitters and Y-splitters, for splitting an income flow stream channel for each melt material, into first and second branched flow channels of equal length which communicate with sets of first and second branched exit ports, each set in an axially-aligned, spaced pattern in different peripheral surface portions of the device;drive means in communication with separate valve means for each nozzle, for simultaneously and identically driving the valve means in each co-injection nozzle, to there simultaneously and identically initiate, regulate and terminate the flow of the respective polymer melt material streams, the drive means including a sleeve shuttle for each sleeve, a pin shuttle for each pin, each connected to common moving means including a sleeve cam bar and a pin cam bar;control means for moving the common moving means in a desired mode to provide the identical, simultaneous movements of the valve means and identical, simultaneous flow control of corresponding materials in each nozzle;a free floating runner system wherein runner means, including a runner block and its runner extension, are mounted on their axial center lines on support means, with a gap between the runner structures and surrounding structures to allow the runner structures to freely thermally expand radially and axially;a force compensation system comprised of means, preferably hydraulic, for providing a forward force to the runner structures to offset any rearward force from axial floatation of the runner means and to provide an on-line, effective pressure contact seal between the nozzle sprues and injection cavity sprues;a runner system providing a substantially equal flow path and experience to corresponding polymer melt material flow streams fed to corresponding passageways in each co-injection nozzle, for forming corresponding layers in each injected article; andapparatus for injection molding and blow molding multi-layer plastic articles, employing the valve means and a fewer number of means for displacing polymer melt materials than there are layers of such materials in the article formed;combinations of the aforementioned and other apparatus and devices, with and without the valve means, and with and without means for displacing and pressurizing each polymer melt material from its source to the co-injection nozzles.Methods for injection molding and injection blow molding articles by means of unit cavity and multi-cavity, multi-layer injection molding and injection blow molding machines are provided, which, in preferred embodiments, include:methods of initiating, regulating and terminating the respective flows of polymer melt material flow streams through the co-injection nozzle orifices, preferably with, but also without the use of valve means, to force thin articles, including parisons and containers comprised of at least three, preferably five layers;methods of doing the above with valve means, and with flow balancing and directing means, involving selectively moving the valve means to various positions which block and unblock the nozzle orifices to form the articles, to provide them with desired characteristics, and to control the relative thicknesses, uniformities and radial positions of the respective layers, especially the internal layer of the article;methods for doing the above with valve means, and with flow balancing and directing means, involving selectively moving the valve means to various positions which block and unblock the nozzle orifices to form the articles, to control the final lateral location of the internal layer within the wall of the injected article;methods of doing the above with and without valve means, and with flow balancing and directing means, in conjunction with pressurizing one or more polymer melt materials, to precisely control the relative flows of the respective polymer melt materials into and through the nozzle central channels and into the injection cavities;methods of initiating flow of a melt stream of polymeric material substantially simultaneously from all portions of an annular passageway orifice into the central channel of a co-injection nozzle of a multi-polymer injecting molding machine for forming multi-layer articles, by providing a melt material in the passageway while preventing the material from flowing through the orifice, subjecting the material to a pressure which at all points about the orifice is greater than the ambient pressure of a flowing melt stream of another polymeric material through the central channel, at all circumferential positions which correspond to said points, and allowing the pressurized material to flow through the orifice to obtain the simultaneous onset flow. The flowing pressurized material has a leading edge sufficiently thick about its annulus that the marginal end portion of the internal layer in the side wall of the injection molded article is at least 1% of the total thickness of the side wall. These methods can be applied to runner systems which extend from reciprocating sources of polymeric melt material displacement to the orifices of a multi-material co-injection nozzle by providing the aforementioned pressure to the polymeric melt material in the runner system.methods of doing the above wherein the pressure subjecting step is effected in two stages, first by providing a residual pressure lower than the desired pressure, and then, before or upon effecting the allowing step, raising the level of the pressure to the desired pressure at which the internal layer material flows through the orifice.methods of prepressurizing at least one polymer melt material, preferably for the internal layer, in its respective passageway whether or not its orifice is blocked by physical means, to provide a uniform onset flow of the melt material simultaneously over all points of its orifice into the central channel, to avoid time bias with respect to the energy of the flow of the material into the central channel, and to provide articles having the leading edge of their internal layer uniformly disposed about the marginal edge portion of the articles if they have no side wall, and about the marginal end portion of the articles, such as parisons and containers, if they have a side wall;methods of injection molding and blow molding articles having the aforementioned uniform leading edge,--and/or having an internal layer thicker in the bottom wall than in the side wall, wherein the bottom wall is, on average, thinner than the side wall of an article, --and/or having in a five layered article, the terminal end of the internal layer(s) encapsulated within intermediate layer material, preferably an adherent material;methods of injection molding and blow molding multi-layer plastic articles having an internal layer whose marginal end portion is folded over within a side wall of the article, by introducing the internal layer material at a first location at the interface between a core stream of material which is to form one surface layer of the article, and an annular stream of material which is to form the other surface layer of the article, and moving the introduced annular stream of third material from its first location which is not coincident with the fast flow streamline, to a second location more proximate to, or coincident with, or across from, the fast flow streamline in the central channel of the nozzle;methods of overcoming bias of a portion of the terminal end of the internal layer of a multi-layer injection blow molded container by folding over the biased terminal end to provide a substantially unbiased overall leading edge of this internal layer;methods of forming an injection molded multi-layer rigid plastic parison for forming a blow molded container whose side wall marginal end portion has a portion of its internal layer folded over, comprising, during injection of the parison, causing a portion of the internal layer to fold over as the layer moves into the through the cavity;methods of simultaneously forming substantially identical injection molded articles in each of a plurality of injection cavities using separate, simultaneously driven valve means in each co-injection nozzle;methods of utilizing the valve means in a co-injection nozzle to assist in knitting the internal layer material to provide a continuous internal layer in the sprue or bottom area of the injected article, parison or container;methods of utilizing the valve means in a co-injection nozzle to assist in encapsulating the internal layer material within structural layer material to provide a completely encapsulated internal layer in the sprue or bottom area of the injected article, parison or container;methods utilizing the valve means, for very rapidly effecting simultaneous initiations, regulations and terminations of flows of combinations of at least three polymer melt material flow streams, in each co-injection nozzle of a multi-coinjection nozzle injection molding machine; andmethods of controlling the flows of polymeric material streams into the central channel of a co-injection nozzle by employing valve means in combination with fewer means for displacing the polymer melt materials, then there are layers in the article, parison or container to be formed.Injection molded and injection blow molded multi-layer substantially rigid plastic articles are provided, which, in preferred embodiments, include:articles having 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 aforementioned articles wherein the folded over portion if toward the inside or the outside of the side wall;the aforementioned articles, parisons, and containers, open-ended, or closed with end closures double seamed thereto or flexible lids secured thereto by an adherent, or heat seal, or other suitable means;the aforementioned articles wherein the folded over portion and any not folded over portion of the marginal end portion of the internal layer, extends substantially uniformly into the marginal end portion of the side wall of the article, parison or container;at least five layer plastic articles having side and bottom walls, and 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; andmulti-layer injection molded plastic containers each of whose side wall is comprised of at least three layers, wherein--the ratio of the internal layer thickness in the bottom wall relative to the total bottom wall thickness is on the average greater than the ratio of the internal layer thickness in the side wall relative to the total side wall thickness,--the bottom wall total thickness is less than the side wall total thickness and the thickness of the internal layer in the bottom wall is at least equal to the average thickness of the internal layer in the side wall,--the bottom wall total thickness is less than the total thickness of the side wall, and, in a central portion of the bottom wall, the internal layer thickness is greater than the average thickness of the internal layer in the side wall, or--the average bottom wall total thickness is less than the average side wall total thickness, and at least a portion of the internal layer is thicker in the bottom wall than the average thickness of the internal layer in the side wall.