WO2003064134A1 - Buse quatre couches pour fabrication d'articles quatre couches - Google Patents

Buse quatre couches pour fabrication d'articles quatre couches Download PDF

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Publication number
WO2003064134A1
WO2003064134A1 PCT/US2003/003025 US0303025W WO03064134A1 WO 2003064134 A1 WO2003064134 A1 WO 2003064134A1 US 0303025 W US0303025 W US 0303025W WO 03064134 A1 WO03064134 A1 WO 03064134A1
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WO
WIPO (PCT)
Prior art keywords
nozzle
die
extrusion
layers
layer
Prior art date
Application number
PCT/US2003/003025
Other languages
English (en)
Inventor
Douglas Sabin
Paul Swenson
Original Assignee
Kortec, Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Kortec, Inc. filed Critical Kortec, Inc.
Publication of WO2003064134A1 publication Critical patent/WO2003064134A1/fr

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
    • B29C45/16—Making multilayered or multicoloured articles
    • B29C45/1603—Multi-way nozzles specially adapted therefor
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
    • B29C45/16—Making multilayered or multicoloured articles
    • B29C45/1642—Making multilayered or multicoloured articles having a "sandwich" structure
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
    • B29C45/16—Making multilayered or multicoloured articles
    • B29C45/1642—Making multilayered or multicoloured articles having a "sandwich" structure
    • B29C45/1643—Making multilayered or multicoloured articles having a "sandwich" structure from at least three different materials or with at least four layers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
    • B29C45/16—Making multilayered or multicoloured articles
    • B29C45/1642—Making multilayered or multicoloured articles having a "sandwich" structure
    • B29C45/1646—Injecting parison-like articles

Definitions

  • the present invention relates to plastic injection molding technology generally, and more specifically to an extrusion nozzle for an injection molding system.
  • Swenson describes a method and apparatus for co-extruding multiple plastic material flowing streams for injecting through a gate region into a mold cavity to produce a molded product.
  • the plastic materials flow from stream sources along a longitudinally extending hollow extruder.
  • the outer (cover) and interior (core) streams are received from the extruder.
  • the streams of flowing plastic materials are combined, with at least one stream that is to serve as an interior core of a resulting molded plastic product within outer and inner streams of plastic material to serve as covering plastic material layers.
  • the combined streams are restricted within and along the longitudinally extending tubular extruder to force the combined streams to flow along concentric annular flow paths within and along the longitudinally extending extruder to the cavity gate region.
  • the annular interior core stream is encased by inner and outer annular covering plastic material stream layers.
  • the concentric annular streams are split along opposite transverse directions to inject into corresponding opposite transverse sections of the cavity.
  • the flow is adjusted so that the annular interior core layer flows along a path of substantially zero gradient of the flow velocity profile transversely of the extruder. This velocity profile enables the leading edge of the (interior) core layer to not become tapered as it flows from the area of combination to the cavity end of the mold gate.
  • Swenson describes an embodiment in which a moveable throttle or restrictor valve pin can vary the percentage of the inner layer of material in the inner annular flow layer vs. the outer annular flow layer of the combined flow stream downstream of the combining area.
  • the thickness of the inner layer relative to the outer layer can be controlled. Changing the relative volumes of the inner and outer layers shifts the position of the core (interior) layer in the mold cavity to produce a part with controlled inner and outer layer thickness on both surfaces of the molded part. If the inner and outer layer flow is evenly distributed between the inner annular flow layer and outer annular flow layer, the inner or outer layer thickness will be similar on inside and outside of the molded part.
  • One aspect of the invention is a die for extruding thermoplastic material, of a type having at least one inlet for receiving the thermoplastic material and at least one outlet for distributing the thermoplastic material.
  • the die has a face, with a channel in the face.
  • the channel provides the outlet for distributing the thermoplastic material.
  • the channel is a closed geometric figure.
  • the channel has at least two arcuate portions. The arcuate portions meet to form at least first and second vertices of said closed geometric figure.
  • the first and second vertices have first and second inlets for receiving the thermoplastic material.
  • a housing has a longitudinal axis. At least three extrusion dies are contained in the housing and aligned with the longitudinal axis. Each die has a face with a die channel in the face. Each die channel is a closed geometric figure. Each die channel has at least one inlet for receiving a respective thermoplastic material. Each die channel provides a respective outlet for feeding a respective one of the plurality of layers of thermoplastic materials to a respective flow channel within the housing.
  • the flow channels deliver the plurality of layers so that at least three of the layers combine within the nozzle at substantially the same coordinate measured along the longitudinal axis.
  • FIG. 1 is an isometric view of an exemplary nozzle according to the present invention.
  • FIG. 2 is an exploded view of the nozzle of FIG. 1 from below, with the valve pin removed for ease of viewing.
  • FIG. 3 is an exploded view of the nozzle of FIG. 1 from above, with the valve pin removed for ease of viewing.
  • FIG. 4 is a top plan view of the nozzle of FIG. 1.
  • FIG. 5 A is a cross section of the nozzle shown in FIG. 4, taken along section line 5A-5A of FIG. 4.
  • FIG. 5B is an elevation view of the nozzle of FIG. 5A, viewed from section line 5B-5B of FIG. 4, showing internal hidden features with dashed lines.
  • FIG. 5C is an enlarged detail of FIG. 5A.
  • FIG. 6 is a cross section of the nozzle shown in FIG. 4, taken along section line 6-6.
  • FIG. 7 is a cross section of the nozzle shown in FIG. 4, taken along section line 7-7.
  • FIG. 8 is a cross section of the nozzle shown in FIG. 4, taken along section line 8-8.
  • FIG. 9 is a cross section of the nozzle shown in FIG. 4, taken along section line 9-9.
  • FIG. 10 is a cross section of the nozzle shown in FIG. 4, taken along section line 10-10.
  • FIGS. 11A-11D are isometric views of the four extrusion dies shown in FIGS. 2 and 3, showing the double extrusion coat hanger die channels.
  • FIG. HE is a plan view of the second extrusion die, shown in FIG. 11B.
  • FIG. 12A shows a timing diagram for injection of inner and outer layer
  • FIGS. 12B through 12E show an article at different times during its formation, when the materials are injected as shown in FIG. 12 A.
  • FIG. 1 shows an exemplary extruder nozzle 100 for extruding an article, such as a pre-form for an injection molded bottle having at least three, preferably four, layers of thermoplastic materials.
  • FIG. 2 is an exploded view of the nozzle 100 of FIG. 1 from below, with the valve pin removed for ease of viewing.
  • FIG. 3 is another exploded view of the nozzle of FIG. 2, as seen from above.
  • the nozzle 100 has a housing or body 102 having a central longitudinal axis A, which passes through the center of the valve throttle pin 132.
  • a nozzle inlet portion 126 seals against the nozzle body 102 creating a pressure boundary that prevents leaks.
  • the nozzle inlet portion 126 has three inlet channels 127a-127c for receiving three different thermoplastic materials.
  • the three nozzle inlet channels 127a- 127c receive three materials, which flow through the nozzle inlet 126 and are coupled to respective ones of the extrusion dies 118, 114, 112 and 108 by way of a distribution layer 124.
  • the distribution layer 124 separates each inlet channel 127a- 127c into a respective pair of feed channels that are equidistant from the inlet channel and oriented parallel to the longitudinal axis A.
  • the equidistant feed channels of distribution layer 124 also have the same cross section and consequentially the same pressure drop from the inlets 127a- 127c.
  • the six feed channels emerging from the distribution layer 124 (two from each material inlet 127a- 127c) form a hexagon shape with each channel located at a vertex.
  • FIGS. 8-10 show the connections between the distribution layer 124 and the various extrusion dies.
  • distribution layer passages 124a and 124b feed the inlets 118c of the first extrusion die 118 and the inlets 108c of extrusion die 108 (by way of longitudinal passages 118u, 114u, and 112u on one side, and passages 118v, 114v and 112v on the opposite side.
  • distribution layer passages 124c and 124d feed the inlets 114c of the second extrusion die (by way of aligned passages 118u on one side and 118v on the opposite side.
  • FIG. 10 distribution layer passages 124a and 124b feed the inlets 118c of the first extrusion die 118 and the inlets 108c of extrusion die 108 (by way of longitudinal passages 118u, 114u, and 112u on one side, and passages 118v, 114v and 112v on the opposite side.
  • distribution layer passages 124e and 124f feed the inlets 112c of the third extrusion die (by way of aligned passages 118q, 114q on one side, and passages 118s, 114s on the opposite side.
  • the distribution layer 124 also has an alignment hole that receives an alignment pin 120, to align the distribution layer and the extrusion dies.
  • At least three extrusion dies are contained in the housing 102 and aligned with the longitudinal axis A.
  • the exemplary nozzle 100 has four extrusion dies 118, 114, 112, and 108, and outputs four annular flow layers of the thermoplastic materials.
  • Each die channel 118b, 114b, 112b and 108b is a closed geometric figure.
  • Each die channel has at least one inlet for receiving a respective thermoplastic material.
  • the exemplary dies have two inlets, 118c, 114c, 112c, 108c.
  • Each die channel 118b, 114b, 112b and 108b provides a respective outlet for feeding a respective one of the plurality of layers of thermoplastic materials to a respective flow channel within the housing 102.
  • the inlets 118c, 114c, and 112c pass through the rear surface of each die, but the inlet 108c is a portion of the channel 108b near the vertices 108h and 108i; the material enters channel 108b through the front face 108a.
  • Each die 118, 114, 112, and 108 has a face (118a, 114a, 112a and
  • Each extrusion die 118, 114, 112, and 108 has a pair of die inlets 118c, 114c, 112c, 108c for receiving a respective thermoplastic material from each one of the pair of feed channels corresponding to that extrusion die.
  • Each of the exemplary extrusion dies has a channel in the form of a "double coat hanger" configuration. Coat hanger type die passages are known in the art, and are described, for example, in U.S. Patent Nos. 4,017,240 and 5,728,407, which are incorporated by reference herein in their entireties.
  • Each double coat hanger channel has at least two arcuate portions.
  • the channel has a kiss shape (best seen in FIG. HE), and the channel has at least a first arcuate portion (e.g., 118d), a second arcuate portion (e.g., 118e), a third arcuate portion (e.g., 118f) and a fourth arcuate portion (e.g., 118g).
  • the first and fourth arcuate portions 118d and 118g meet at the first vertex 118h.
  • the second and third arcuate portions 118e and 118f meet at the second vertex 118i.
  • the first and second inlets 118c that receive the thermoplastic material are located in the first and second vertices 118h and 118i.
  • the first and second vertices 118h, 118i point outwardly, away from a center of the die.
  • the first and second arcuate portions 118d and 118e meet at the third vertex 118 j .
  • the third and fourth arcuate portions 118f and 118g meet at the fourth vertex 118k.
  • the third and fourth vertices 118j , 118k point inwardly, towards a center of the die (which coincides with the central axis A of the nozzle 102, shown in FIG. 1).
  • Each of the exemplary channels 118b, 114b, 112b and 108b has a plane of symmetry S (shown in FIG. HE) substantially midway between the first and second vertices, e.g., 118h and 118i.
  • the first arcuate section 118d and the fourth arcuate section 118g are mirror images of second arcuate section 118e and third arcuate section 118f, respectively.
  • a preferred channel has a second plane of symmetry perpendicular to the plane of symmetry S, passing through the vertices (e.g., 118h, 118i) of the channel along the major axis of the kiss shape.
  • the first arcuate section 118d and the second arcuate section 118e are mirror images of fourth arcuate section 118g and third arcuate section 118f, respectively.
  • the coat hanger configuration allows formation of an extruded sheet by merging a substantially cylindrical runner into a flattened triangular passageway of gradually decreasing thickness.
  • a pair of runners on opposite sides of the die forms an annular extruded layer.
  • the double coat hanger configuration is most easily seen in FIG. 1 IE, which shows the second layer extrusion die 114 in plan view.
  • the kiss-shaped channel is the same or substantially similar in extrusion dies 118, 112 and 108.
  • Channel sections 114d and 114g form a first coat hanger channel portion
  • channel sections 114e and 114f form a second coat hanger channel portion.
  • a respective inlet 114c provides the thermoplastic material to each respective coat hanger channel portion.
  • Each extrusion die channel 118b, 114b, 112b, 108b has a gap and groove geometry that is calculated to create substantially equal pressure drop for any streamline from a nozzle inlet corresponding to the respective thermoplastic material and any location on the annular layer of that one thermoplastic material at a given coordinate along the longitudinal axis.
  • each extrusion die 118, 114, 112, 108 creates a respective annular layer of uniform thickness during operation of the nozzle 100.
  • the shapes of the gap and groove are determined by material behavior at certain assumed flow rates and temperatures.
  • the exemplary double radial coat hanger dies 118, 114, 112, 108 are "kiss" shaped with the inlets 118c, 114c, 112c, 108c at the corners 118h, 118i, 114h, 114i, 112h, 112i, 108h, 108i of the "mouth” and an annular exit in the middle (Best seen in FIGS. 5 A and 6-10.
  • the kiss-shaped channels of the extrusion dies 118, 114, and 112 are rotated 120 degrees from each other around the longitudinal axis A.
  • This kiss shape leaves room near the perimeter of the die for independent through-passages that connect to passages in other dies above and/or below without interfering with the layer of material distributed by the kiss-shaped channel.
  • the kiss shape when repeated at 120 degree intervals also permits feed channels for other layers to be aligned axially and contained within the nozzle body 102.
  • This solves a major problem with multi-layer design in that certain material must always pass by the means of distributing other layers into annular layers. If prior art techniques are used, this would create large nozzle diameters. Large nozzle diameters are costly because they limit the number of parts that can be molded on a particular size platen - machine size.
  • the kiss shaped channels 118b and 108b of first and fourth extrusion dies 118 and 108 are aligned with each other.
  • the channels 118b, 114b, 112b, 108b each have a base surface 118m
  • the base surfaces 118m, 114m, 112m 108m are sloped, so that a distance between the face 118a, 114a, 112a, 108a (respectively) and the base surface 118m, 114m, 112m, 108m (respectively) at the plane of symmetry S is less than a distance between the face and base surface adjacent to either of the first vertices 118h, 114h, 112h, 108h or the second vertices 118i, 114i, 112i, 108i.
  • the extrusion die 118 is oriented so that the first die channel 118b faces downward, towards the tip of the nozzle 100, with the base 118m sloping downwardly from the inlets 118c to the center of FIG. 5B.
  • the extrusion die 114 is oriented so that the second die channel 114b faces downward, towards the tip of the nozzle 100, with the base 114m sloping downwardly from the inlets 114c (in and out of the page, obscured in FIG. 5B) to the front FIG. 5B.
  • the extrusion die 112 is oriented so that the third die channel 112b faces downward, towards the tip of the nozzle 100, with the base 112m sloping downwardly from the inlets 112c to the center of FIG.
  • the extrusion die 108 is oriented so that the first die channel 108b faces upward, away from the tip of the nozzle 100, with the base 108m sloping upwardly from the inlets 108c to the center of FIG. 5B.
  • the width of each channel is also smaller at the center than at either of the first and second vertices, as best seen in FIG. 1 IE.
  • the flow channels deliver a plurality of layers of thermoplastic material from the extrusion dies so that at least three of the layers combine within the nozzle at substantially the same coordinate 150 measured along the longitudinal axis A.
  • the exemplary nozzle 100 uses particular flow channels to create four- layer annular flow from four concentric exit orifices 118n, 114n, 112n, 108n.
  • the point of combination 150 of the layers is nearly simultaneous, as best seen in FIG. 5C.
  • a flow dam insert 116 keeps the flow layers from extrusion dies 118 and 114 separate from each other until the longitudinal coordinate of combination 150 is reached (i.e., until the first and second layers substantially reach a coordinate 150 along the longitudinal axis A at which the second layer contacts the third layer of thermoplastic material.). This eliminates surfaces that need to be wiped clean when an interior layer is shut off.
  • the separation disk 110 keeps the flow from extrusion dies
  • the fourth extrusion die 108 delivers a fourth layer of material substantially at the coordinate along the longitudinal axis at which the second layer of thermoplastic material contacts a third layer of thermoplastic material.
  • additional flow dams and/or separator disks may be used to maintain the layers of thermoplastic material separate from each other until all of the layers reach substantially the same longitudinal coordinate.
  • each of the extrusion dies 118, 114, 112 and 108 has a double coat hanger channel 118b, 114b, 112b and 108b, respectively, the configuration of through-passages in each die is unique, as shown in FIGS. 5A and 6- 10.
  • the second one of the extrusion dies receives at least a second and a third material by way of the first extrusion die, and passes at least the third material on to the third extrusion die.
  • the first one of the extrusion dies has thee pairs of passages therethrough, for permitting three respective materials to pass from the three nozzle inlets through the first extrusion die.
  • the three exemplary pairs of passages are coupled to second, third and fourth extrusion dies, respectively.
  • a portion of the flow is used to feed two modified coat hanger die channels 118b that distribute the flow from the circular feed channels into an annular flow channel 118n that surrounds the valve pin 132 (FIG. 5C).
  • This material forms the inside layer at the exit 106a of the nozzle 100.
  • the inlets 118c are aligned with passages 114u and 114v that go directly through the second die 114, passages 112u and 112v that go directly through the third die 112, and passages HOu and HOv that go directly through separation disk 110, terminating at the inlets 108c of die 108.
  • the remaining flow of the first material that is not distributed to annular flow channel 118n at the first layer 118 passes through layers two and three (dies 114 and 112) to layer four (die 108) where it makes the outside layer of the article.
  • An additional passage 118p through die 118 receives the alignment dowel pin 120.
  • the second extrusion die 114 receives the first, second and third materials by way of the first extrusion die 118, and passes the first and third material on to the third extrusion die 112.
  • layer 2 extendrusion die 114 accepts the six feed channels from layer 1 and uses two of them — inlets 114c are fed by passages 118r and 118t of die 118 — to create layer two of the article as above.
  • the material in inlets 114c flows into annular flow channel 114n (FIG. 5C).
  • the remaining four channels 114q, 114s, 114u and 114v pass through layer 2 (die 114) to layer 3 (die 112).
  • An additional passage 114p through die 114 receives the alignment dowel pin 120.
  • the third extrusion die 112 receives the first and third materials and passes the first material on to the fourth extrusion die 108.
  • Layer 3 (extrusion die 112) accepts the four feed channels 114q, 114s, 114 u and 114v from layer 2 (die 114) and uses the material flow from two of them (a first passage 118q, 114q and a second passage 114s, 114s, entering through inlets 112c) to create the third annular layer of material as above.
  • the material flows into the annular flow channel 112n (FIG. 5C).
  • the remaining two channels 114u and 114v pass through layer 3 and the separation disk 110 to layer 4 (extrusion die 108).
  • the fourth extrusion die 108 receives the first material by way of the first, second and third extrusion dies 118, 114 and 112, respectively, and provides a second annular flow of the first material to be output from the nozzle 100. This forms the outermost annular cover layer of the article.
  • layer 4 extendrusion die 108 accepts two feed channels from the passages in the separation disk 10, which in turn receive flow via a first passage comprising inlets 118c, channel portions 118u and 118v, second layer passages 114u and 114v and third layer passages 112u and 112v from die 112.
  • Extrusion die 108 receives the flow at an inlet portion 108c of the die, and uses the material to create the fourth annular layer, the outside layer of the article.
  • the material in die 108 flows into annular flow channel 108n (FIG. 5C).
  • An additional passage 108p through die 108 receives the alignment dowel pin 120.
  • the nozzle 100 has a gate 106a.
  • the first, second and third layers or thermoplastic material are combined into a co-extrusion substantially at the same coordinate 150 along the longitudinal axis A, and the co-extrusion is provided at an exit of the nozzle 100.
  • the respective die channels 118b, 114b of at least the first and second extrusion dies 118 and 114 face the gate 106a of the nozzle 106, and the respective die channel 108b of one of the at least three extrusion dies 118, 114, 108 other than the first and second extrusion dies faces away from the gate 106a of the nozzle.
  • the first three dies 118, 114, 112 face the gate 106a
  • the fourth die 108 faces away from the gate.
  • an alignment pin 130 aligns the body 102 with the inlet portion 126.
  • a plurality of fasteners 128 fasten the inlet portion 126 to the body 102.
  • An inlet seal 122 prevents leakage between the tubular extension on the top of the first extrusion die 118 and the inlet portion 126.
  • a tip seal 104 between the tip insert 106 and the tip of the nozzle body 102.
  • the second and fourth layers of the co-extrusion are formed of the same material.
  • the nozzle structure described above may be used to perform functions that were not practical with prior art nozzles.
  • the exemplary nozzle described above has four extrusion dies 118, 114, 112, 108 to feed four respective layers of material to a gate 106a of the nozzle 100; the first and fourth extrusion dies 118, 108 receive a first one of the thennoplastic materials from a common source.
  • the position of the throttle pin 132 is adjustable to vary a ratio between a flow rate of the first thermoplastic material through the first extrusion die 118 and a flow rate of the first thermoplastic material through the fourth extrusion die 108.
  • a straight throttle pin 132 e.g., pin 132 in FIG. 10
  • a throttle pin having a diameter that varies along its length e.g., pin 132' in FIG. 5 A, only a portion of which is shown.
  • One variation of the method includes the step of controlling flow of the first thermoplastic material so that the innermost one of the annular layers is thinner than an outermost one of the annular layers.
  • the first material is PET, forming the innermost and outermost layers of the article, which is a pre-form for a bottle.
  • the second material is a scavenging barrier layer, forming a thinner innermost (first) layer results in the scavenger layer being located close to the contents of the bottle. This enhances the ability to reduce the amount of dissolved oxygen in the inner skin, to reduce oxidation of the contents of the bottle.
  • the step of flow of the first thermoplastic material can be controlled so that the innermost one of the annular layers is thicker than an outermost one of the annular layers.
  • the third layer from the inside
  • the barrier layer is next to a relatively thin outermost layer, and the barrier layer has an environment with a lower relative humidity.
  • the nozzle 100 can accommodate three different materials, it provides great flexibility.
  • one of the interior annular layers may be recycled plastic.
  • the recycled plastic can be thoroughly encapsulated between inner and outer layers of virgin plastic.
  • a barrier layer can be incorporated between the inner virgin plastic layer and the recycled plastic layer.
  • the exemplary nozzle allows precise control over the relative thickness of each of the four layers.
  • the exemplary embodiment of the invention is well adapted for extruding articles in accordance with the teachings of US 6,187,241 Bl, wherein a multilayer article is formed from a flow having an annular profile.
  • the article can be in the configuration of a disk or a tube.
  • the tube could be a preform that is subsequently blown into a bottle or used in the as molded shape, hi the case of a tube configuration the material will flow through the gate in the center of the closed end of the tube to the open end forming layers.
  • the articles created with this nozzle have four layers of three materials or fewer.
  • the Inner and Outer layers are formed of the same material, usually PET (Polyethylene Terephthalate), but could include many other resins including Polypropylene, Polyethylene and Polyethylene Naphthalate (PEN).
  • PET Polyethylene Terephthalate
  • PEN Polyethylene Naphthalate
  • the inner and outer layers can fully encapsulate the inner core layer and the outer core layer on the opened end and the closed end of the article. This configuration is shown at different times during its formation in FIGS. 12B tol2E.
  • FIG. 12A is an exemplary timing diagram for injection of the three materials for the inner and outer layers, and the first and second core layers.
  • injection of the first core layer material begins while the inner and outer layer material is still being injected
  • the second core layer material begins injection while both the inner and outer layer material and the first core layer material are being injected.
  • injection of the three materials is completed in the opposite order from the beginning of injection.
  • the second core layer completes injection, then the first core layer, and finally, the inner and outer layer materials.
  • the first-flowing interior layer CI in this case the outermost interior layer in the molded object
  • the second- flowing interior layer C2 starts flowing at time S2 which also corresponds with the reduction of the flow rate of the combined imier and outer layer flow.
  • FIG. 12B shows the flow in the nozzle and partially-filled cavity at time A of FIG. 12A; this time being between the time SI and S2.
  • the leading edge of the first-flowing interior layer CI is on the zero velocity gradient point of the combined flow velocity profile, thus assuring its uniform penetration in the molded object.
  • FIG. 12C shows the partially filled cavity at time B of FIG. 12A.
  • the leading edge of the first-flowing interior layer CI remains on the zero velocity gradient, while the later-flowing portions of the first-flowing interior layer are moved off the zero velocity gradient by the second- flowing interior layer C2, and are closer to the wall of the extruder.
  • FIG. 12D shows the position of the flows in the nozzle and cavity at time C of FIG. 12 A.
  • the second-flowing interior layer C2 has ceased flowing at time S3, thereby allowing the final flow portion of the first-flowing interior layer CI to return to the zero gradient just before its flow is terminated, at S4.
  • FIG. 12E shows the filled cavity when the trailing edge of the first- flowing interior layer CI has been injected into the cavity by the continued flow of the combined inner and outer layer flow (I and O) after time C, of FIG. 12 A.
  • the filled cavity shows the first-flowing interior layer CI closer to the outer wall in the portions of the filled cavity corresponding to the simultaneous flow of the second- flowing interior layer C2.
  • the leading and trailing edges of the core layer CI lie along the zero velocity gradient. This ensures that the longitudinal positions of the leading edge and trailing edge are substantially uniform all around the article, even if the material is injected slightly off center, hi the remaining portion of the core layer, the second-flowing interior layer C2 overlies the zero velocity gradient. This allows the second-flowing interior layer to constitute a relatively large percentage of the total mass flow.
  • the second flowing core layer C2 may be recycled or off-specification polymer, so that it is cost effective to use a relatively thick layer C2 encapsulated in plastic.
  • the centroid of the combined core layers CI and C2 is on the zero velocity gradient.
  • the inner core layer and the outer core layer can be used in combination to increase the performance of the container or lower the cost of the container.
  • Table 1 lists five different examples of combinations of inner and outer core layers, and exemplary benefits for each configuration. These are only exemplary, and one of ordinary skill in the art will understand that other configurations are also possible using the exemplary nozzle.
  • a high barrier polymer such as MXD6 or Ethylene Vinyl Alcohol Polymer (EVOH) can be used in the outer core layer CI, and Recycled or off-specification polymer can be used in the inner core layer C2.
  • Most barrier materials perform better in lower relative humidity, so using the barrier in the outer core layer CI can improve the performance of the barrier and the value of the container.
  • the outer core layer CI can also be an oxygen-scavenging barrier for oxygen sensitive contents. Because both core layers can be encapsulated, the recycled skin material in layer C2 does not contact the contents of the article and does not require the pedigree associated with material used in direct food contact.
  • an oxygen scavenger is used in the inner core layer C2 and a barrier is used in the outer core layer CI.
  • an oxygen scavenger is used in this configuration the performance of the container is improved in many ways.
  • an oxygen scavenger is positioned more closely to the contents of the container, it can scavenge oxygen that is trapped in the container during the filling process as well as the oxygen in the inner layer of the bottle.
  • the inner skin layer of the bottle is also thinner so it contains less oxygen upon filling the bottle.
  • the outer core layer CI of barrier and the outer layer O protect the scavenging layer from oxygen in the atmosphere. This extends the life of the oxygen scavenger and consequently the performance of the bottle.
  • an oxygen scavenger or oxygen-scavenging barrier material can be used on the inside layer C2, and recycled or off-specification material may be used in the outside core CI. h this configuration the performance of the container is improved as described above except the oxygen scavenger is protected by the outer core layer CI of recycled polymer and the outer layer O instead of a barrier layer and outer layer.
  • either of the inner of outer core layers may be a humidity control barrier layer or an electromagnetic shielding layer.

Landscapes

  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Mechanical Engineering (AREA)
  • Extrusion Moulding Of Plastics Or The Like (AREA)

Abstract

L'invention concerne une buse (100) d'extrusion d'un article qui comporte au moins trois couches de matériaux thermoplastiques. Un logement (102) comprend un axe longitudinal sur lequel s'alignent au moins trois matrices d'extrusion. Chaque matrice (108, 112, 114, 118) comprend une face dotée d'un canal à forme géométrique fermée. Chaque canal de matrice (114b, 118b) comprend au moins un orifice d'entrée pour recevoir un matériau thermoplastique respectif, et un orifice de sortie respectif pour fournir une des couches de matériaux thermoplastiques à un canal d'écoulement respectif dans le logement (102). Les canaux d'écoulement distribuent la pluralité de couches de façon à ce qu'au moins trois d'entre elles s'associent dans la buse (100) selon pratiquement la même coordonnée mesurée le long de l'axe longitudinal.
PCT/US2003/003025 2002-02-01 2003-01-31 Buse quatre couches pour fabrication d'articles quatre couches WO2003064134A1 (fr)

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US35340802P 2002-02-01 2002-02-01
US60/353,408 2002-02-01

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WO2003064134A1 true WO2003064134A1 (fr) 2003-08-07

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2007012317A2 (fr) * 2005-07-27 2007-02-01 A & E Applikation Und Entwicklung Gmbh Dispositif de fabrication de pieces moulees par injection a plusieurs constituants
WO2018098563A1 (fr) 2016-12-01 2018-06-07 Husky Injection Molding Systems Ltd. Géométrie de canal pour favoriser un profil de vitesse uniforme et/ou un profil de température uniforme pour un écoulement de matière fondue annulaire ou partiellement annulaire

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US3921856A (en) * 1972-09-27 1975-11-25 Erhard Langecker Injection molding nozzle
US3947177A (en) * 1973-09-13 1976-03-30 Schloemann-Siemag Aktiengesellschaft Apparatus for injection molding of multi-layer bodies of thermoplastic
US5028226A (en) * 1986-07-05 1991-07-02 Cmb Foodcan Plc Multi-cavity, co-injection molding apparatus
US5238715A (en) * 1989-12-26 1993-08-24 Aluminum Company Of America Food or beverage container or container panel
US5763033A (en) * 1996-01-30 1998-06-09 Becton, Dickinson And Company Blood collection tube assembly
US5914138A (en) * 1996-09-27 1999-06-22 Kortec, Inc. Apparatus for throttle-valving control for the co-extrusion of plastic materials as interior core streams encased by outer and inner streams for molding and the like
US6077578A (en) * 1995-06-26 2000-06-20 The Elizabeth And Sandor Valyi Foundation, Inc. Molded plastic food and beverage container and method
US6350401B1 (en) * 1997-10-23 2002-02-26 Mold-Masters Limited Method of multi-layer injection molding
US20030026933A1 (en) * 2001-07-31 2003-02-06 John Kermet Method and apparatus for using a sprue to reduce the size of a core layer hole in an injection molding process

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3921856A (en) * 1972-09-27 1975-11-25 Erhard Langecker Injection molding nozzle
US3947177A (en) * 1973-09-13 1976-03-30 Schloemann-Siemag Aktiengesellschaft Apparatus for injection molding of multi-layer bodies of thermoplastic
US5028226A (en) * 1986-07-05 1991-07-02 Cmb Foodcan Plc Multi-cavity, co-injection molding apparatus
US5238715A (en) * 1989-12-26 1993-08-24 Aluminum Company Of America Food or beverage container or container panel
US6077578A (en) * 1995-06-26 2000-06-20 The Elizabeth And Sandor Valyi Foundation, Inc. Molded plastic food and beverage container and method
US5763033A (en) * 1996-01-30 1998-06-09 Becton, Dickinson And Company Blood collection tube assembly
US5914138A (en) * 1996-09-27 1999-06-22 Kortec, Inc. Apparatus for throttle-valving control for the co-extrusion of plastic materials as interior core streams encased by outer and inner streams for molding and the like
US6350401B1 (en) * 1997-10-23 2002-02-26 Mold-Masters Limited Method of multi-layer injection molding
US20030026933A1 (en) * 2001-07-31 2003-02-06 John Kermet Method and apparatus for using a sprue to reduce the size of a core layer hole in an injection molding process

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2007012317A2 (fr) * 2005-07-27 2007-02-01 A & E Applikation Und Entwicklung Gmbh Dispositif de fabrication de pieces moulees par injection a plusieurs constituants
WO2007012317A3 (fr) * 2005-07-27 2007-08-02 A & E Applikation Und Entwickl Dispositif de fabrication de pieces moulees par injection a plusieurs constituants
WO2018098563A1 (fr) 2016-12-01 2018-06-07 Husky Injection Molding Systems Ltd. Géométrie de canal pour favoriser un profil de vitesse uniforme et/ou un profil de température uniforme pour un écoulement de matière fondue annulaire ou partiellement annulaire
EP3548249A4 (fr) * 2016-12-01 2020-08-12 Husky Injection Molding Systems Luxembourg IP Development S.à.r.l Géométrie de canal pour favoriser un profil de vitesse uniforme et/ou un profil de température uniforme pour un écoulement de matière fondue annulaire ou partiellement annulaire
US11104049B2 (en) 2016-12-01 2021-08-31 Husky Injection Molding Systems Ltd. Channel geometry for promoting at least one of a uniform velocity profile and a uniform temperature profile for an annular or part-annular melt flow

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