9 Three-layer Extrusion Blow Mold Cut-away viewfilm bubblematerial 1material 2material 3Jan-03,This is a cut-away of a three layer coextrusion die.The point where the three layers come together can be clearly seen.
10 Blown Film Line With Slitter Jan-03,Bubble diameters an be 9 feet and more. The larger the bubble the higher the collapsing frame. Large bubbles require a 4-story building.Fig.10.7
11 Blown Film Line Showing Die & Bubble Jan-03, August 04,This is high density polyethylene being blown into a bubble. The freeze line where the PE crystallizes and becomes translucent clarity can be clearly seen.
12 Aluminum Foil Household foil is typically 17.5 mm (0.0007 inches) Available in gauges as low as 7 mm ( inches)Pin holing is present below 12 mm ( inches)Foil is susceptible to flex crackingMost foils are supported with plastic and/or paperFeb-03, October 04,Most foils used in flexible packaging are less than inches. Exceptions are lidstocks for tubs and tablet blister-card backings.Unsupported foil used for some lid-stock & tabletpush-through packaging
13 Aluminum Foil Characteristics Intact foil is a 100% barrier to all gasesBest deadfold propertiesEasily punctured (tamper evidence)Reflective of radiant heatConductive (induction sealing)Decorative appeal: all reflective metallics are aluminumDec-02, November 04,Ice cream bars are often wrapped in foil or metallized plastic to reflect the sun’s radiant heat.
14 Foil Packaging Applications Unsupported foil, non-sealablee.g. confection and cheese wrapsUnsupported foil, heat sealablee.g. lidding stock, pharmaceutical tabletbacking materialSupported foil, non heat sealablee.g. decorative wraps, label stockFeb-03,Supported foil, heat sealablee.g. high barrier pouches and sachetslidding stock, retort pouches
16 Aluminum Metallized Film Provides reflective metallic appearanceImproves moisture, aroma, light and oxygen barrierOxygen barrier improved:up to fifty times for OPP, up to ten times for PETStatic dissipative applicationsOPP, PET, & PA (nylon) most common packaging filmsDec-02, November 04,
17 Why Laminate? Laminate: A product made by bonding together two or more materialsThere is no perfect, universal packaging materialLaminates assemble materials with individually desirable properties to create an optimum material
18 Laminate Properties Mechanical properties tensile strength stiffness coefficient of friction use temperatureselongation formabilityBarrier properties as requiredoxygen barrier essential oil barrierwater vapor barrier light barrierDec-02,
19 Laminate Properties Sealability most flexible packaging is heat sealed most heat seals are polyethylene basedother polymers used more critical applicationsAesthetic appearanceclaritysurface glossreflective metallicsOctober 2000, November 04,
20 Describing Packaging Laminate Note:Packaging laminate plies are alwayslisted from the outside to the insideMay-03,
22 Wet Bond Laminator Fig. 14.10 Dec-02, These are simple single function laminators being illustrated. Actual production laminators might combine both wet and dry bonding capabilities in one line or have several adhesive or coating application stations. Complex extrusion for high production volumes (such as would be needed for Tertra Bloc laminates) might have 4 or 5 extrusion laminating stations in one line.Fig
23 Dry Bond Laminating Fig. 14.11 Dec-02, May-04, Adhesive bonding can create better bonds with more materials.Fig
24 Solventless Laminating October 04, November 04,Solventless laminating uses catalyzed or or two-partreactive adhesives
25 Extrusion Laminating Fig. 14.9 Dec-02, Feb-03, May-03, Most extrusion laminators use PE as the adhesive medium.Extrusion laminating takes longer to set up than simply adhesive bonding, and so is more suitable for longer runs.The extruded film however will be thicker and stiffer than an adhesive application, making for a thicker and stiffer laminate. The extrudate could be pigmented white and if laminated to a reverse printed clear film could eliminate the need for a white opaque printing plate.Great care must be taken to avoid gauge bands on the finished roll.Fig. 14.9
26 Hot Tack The bond strength of the seal while still hot Critical for most form-fill-seal machinesDetermines how quickly product can be droppedinto a pouchNovember 04,
27 Common Heat- Seal Materials ionomer (e.g. Surlyn, seals through contaminants )acid copolymer (good foil bond, chemical resistance)metallocene polyethylene (low temp, fast seal)LLDPE (good hot tack, tough, wide seal temp.)PE/EVA (soft film, low seal temperature)medium-density polyethylene (stiffer, better barrier)cast polypropylene (stands higher temperatures)low-density polyethyleneDec-02, Feb-03, May-03,The table has the lowest cost and performance heat seals at he bottom. As you go up the table, cost and performance increases.DuPont’s Nucrel product is a common acid copolymercostbond qualityTable 14.5
28 Sealing Mediums Compared Feb-03,Source: M. Lutterotti, DuPontFigure 14.6
30 Example Laminations printed paper foil foil Retort pouch Aseptic box polyethylenepoly(ethylene terephthalate)printed paperfoilfoilsealing mediumsealing mediumRetort pouchAseptic boxprinted polypropylenesaran-coated nylonDec-02,The typical aseptic drink box sealing medium is actually two layers: PE and Surlyn. The Surlyn is need to form a very strong bond to the foil. The Surlyn layer for luncheon meat allows sealing through grease smears.metallized polypropylenesealing mediumsealing medium (Surlyn)Snack food bagLuncheon meat traySee Figures & 14.14
31 Example Laminations printed polyethylene surface print Ethylene-vinyl alcoholpaperpolyethylenepolyethyleneHigh oxygen barrierfoilsealing mediumpolyethylenepoly(ethylene terephthalate)sealing medium (vinyl)overlacquerSingle-service lidding stockprinted foilBasic food pouch laminateMay-03, November 04,Putting a higher softening point material such as PET to the outside allows for hotter sealing bar temperatures which in turn can increase heat sealing speed on VFFS and HFFS machines. On the other hand, a lap seal would require a heat sealable material on both sides of the laminate.For applications where the foil is being used as a barrier, the foil must be to the inside of the pouch. Reflective metallics as a decorative value are more commonly achieved by with metallized paper or plastic.(For barrier applicationsfoil to the inside)See Figures 14.13, 14.14
32 Laminated Collapsible Tube Construction Injected molded tipFinishedtube1Formed bodyFoilClear LDPEpaperSealing mediumPrinted white PEEAAHighbarrierinsertDec-02, November 04,Laminateroll stock
33 Vertical Form-Fill-Seal (VFFS) Dec-02, November 04,CoF is critical!Fig. 14.2
34 VFFS Pouch Seals Compared Fin seal Lap SealSeals inside surfacesUses more materialDon’t cover UPC!Seals outside to insideBoth surfaces needsealing mediumUse less materialOct. 02, Dec-02,Fig. 14.5
36 Common HFFS Pouch Styles Three-sidesealed pouchGusseteddesignsConventional pouch has three-side sealCan be made into various stand-up designsSome stand-up pouches are pre-made in a separateoperationOct. 02, Dec-02,Fig. 14.5
37 Multi-Lane Form-Fill-Seal Dec-02, Feb-03,Most condiment sachets are made this way. Machines can be 12 and 16 stations across.Fig. 14.4
38 Stand-Up Pouch Examples Feb-03,Stand-up pouches have become very popular over the last few years.
40 Film Thickness Measurement Inch Gauge Mil Micrometre0.001inch = 100 gauge = 1 mil = 25 mminch = 50 gauge = 1/2 mil = 13 mmISO metric notes:“Micron” is a depreciated term for micrometreone inch = 25.4 millimetres and0.001 inch = 25.4 micrometresDec-02, November 04,
41 Early Universal Barriers PVDC is original high universal barrier polymersEVOH laminated between high moisture barrierpolymers can also provide good universal barrierBut not high enough barrier for critical applicationsMetallizing also produces a high universal barrierBut aluminum metallized films are not transparentDec-02, November 04,This is an added bit to describe some of the recent work on developing high barrier plastic laminates. Much of the development has been aimed at bottle constructions but could be used in laminates.
42 Recent Advances in Achieving Barrier Monolayer polymerspoly(ethylene naphthalate) ($)liquid crystal polymer ($$$)Multilayered constructionsPET/PA/PETPET/EVOH/PETPET/MXD6/PET/ MXD6/PETDec-02, November 04,PEN is a bout three times the cost of PET but has substantially improved barrier properties as well as being capable of hot filling, and being a natural U.V. barrier. LCP is even more costly. The multilayered constructions are currently in use for plastic beer bottles.
43 Recent Advances in Achieving Barrier Interior coatingsSiOx (glass) coating (Glaskin)AlOx aluminum oxide coatingcarbon coating (DLC and Actis)Exterior coatings and interior laminatesepoxy-amine coating (Sealica and Bairocade)copolyester (Amosorb: interior layer)Nanocompositesextremely fine mineral additionsOct. 02, Dec-02,Interior and exterior coating refers to the use of the process for bottles.