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Flexible Packaging Laminates

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Presentation on theme: "Flexible Packaging Laminates"— Presentation transcript:

1 Flexible Packaging Laminates
Lesson 8 Flexible Packaging Laminates October 04, November 04, 第8课 软包装复合材料

2 Plasticating Extruder
Jan-03, Fig. 10.2

3 Cast Film and Sheet Extrusion
Jan-03, Fig.10.4

4 Three-Layer Coextrusion
Jan-03, Fig.10.9

5 Extrusion Cast Film Line Layout
Jan-03, This would be an unoriented material Fig.10.5

6 Machine Direction Orientation
Jan-03, Fig.10.8

7 Cross Direction Orientation
Jan-03, While most people refer to MD and CD, some plastic people call it TD (transverse direction) Fig.10.8

8 Blown-film Die Cross-Section
Oct.02, Fig.10.6

9 Three-layer Extrusion Blow Mold
Cut-away view film bubble material 1 material 2 material 3 Jan-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 cracking Most foils are supported with plastic and/or paper Feb-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 & tablet push-through packaging

13 Aluminum Foil Characteristics
Intact foil is a 100% barrier to all gases Best deadfold properties Easily punctured (tamper evidence) Reflective of radiant heat Conductive (induction sealing) Decorative appeal: all reflective metallics are aluminum Dec-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-sealable e.g. confection and cheese wraps Unsupported foil, heat sealable e.g. lidding stock, pharmaceutical tablet backing material Supported foil, non heat sealable e.g. decorative wraps, label stock Feb-03, Supported foil, heat sealable e.g. high barrier pouches and sachets lidding stock, retort pouches

15 Aluminum Vacuum Metallizing
Feb-03, Fig.14.1

16 Aluminum Metallized Film
Provides reflective metallic appearance Improves moisture, aroma, light and oxygen barrier Oxygen barrier improved: up to fifty times for OPP, up to ten times for PET Static dissipative applications OPP, PET, & PA (nylon) most common packaging films Dec-02, November 04,

17 Why Laminate? Laminate: A product made by bonding together
two or more materials There is no perfect, universal packaging material Laminates assemble materials with individually desirable properties to create an optimum material

18 Laminate Properties Mechanical properties tensile strength stiffness
coefficient of friction use temperatures elongation formability Barrier properties as required oxygen barrier essential oil barrier water vapor barrier light barrier Dec-02,

19 Laminate Properties Sealability most flexible packaging is heat sealed
most heat seals are polyethylene based other polymers used more critical applications Aesthetic appearance clarity surface gloss reflective metallics October 2000, November 04,

20 Describing Packaging Laminate
Note: Packaging laminate plies are always listed from the outside to the inside May-03,

21 Gravure Coating Dec-02, Fig. 14.8

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-part reactive 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 machines Determines how quickly product can be dropped into a pouch November 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 polyethylene Dec-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 copolymer cost bond quality Table 14.5

28 Sealing Mediums Compared
Feb-03, Source: M. Lutterotti, DuPont Figure 14.6

29 Heat Sealing Parameters
Dec-02, Feb-03, Fig. 14.7

30 Example Laminations printed paper foil foil Retort pouch Aseptic box
polyethylene poly(ethylene terephthalate) printed paper foil foil sealing medium sealing medium Retort pouch Aseptic box printed polypropylene saran-coated nylon Dec-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 polypropylene sealing medium sealing medium (Surlyn) Snack food bag Luncheon meat tray See Figures & 14.14

31 Example Laminations printed polyethylene surface print
Ethylene-vinyl alcohol paper polyethylene polyethylene High oxygen barrier foil sealing medium polyethylene poly(ethylene terephthalate) sealing medium (vinyl) overlacquer Single-service lidding stock printed foil Basic food pouch laminate May-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 applications foil to the inside) See Figures 14.13, 14.14

32 Laminated Collapsible Tube Construction
Injected molded tip Finished tube1 Formed body Foil Clear LDPE paper Sealing medium Printed white PE EAA High barrier insert Dec-02, November 04, Laminate roll 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 Seal Seals inside surfaces Uses more material Don’t cover UPC! Seals outside to inside Both surfaces need sealing medium Use less material Oct. 02, Dec-02, Fig. 14.5

35 Horizontal Form-Fill-Seal (HFFS)
Fig. 14.3

36 Common HFFS Pouch Styles
Three-side sealed pouch Gusseted designs Conventional pouch has three-side seal Can be made into various stand-up designs Some stand-up pouches are pre-made in a separate operation Oct. 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.

39 Stand-Up Pouch Examples

40 Film Thickness Measurement
Inch Gauge Mil Micrometre 0.001inch = 100 gauge = 1 mil = 25 mm inch = 50 gauge = 1/2 mil = 13 mm ISO metric notes: “Micron” is a depreciated term for micrometre one inch = 25.4 millimetres and 0.001 inch = 25.4 micrometres Dec-02, November 04,

41 Early Universal Barriers
PVDC is original high universal barrier polymers EVOH laminated between high moisture barrier polymers can also provide good universal barrier But not high enough barrier for critical applications Metallizing also produces a high universal barrier But aluminum metallized films are not transparent Dec-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 polymers poly(ethylene naphthalate) ($) liquid crystal polymer ($$$) Multilayered constructions PET/PA/PET PET/EVOH/PET PET/MXD6/PET/ MXD6/PET Dec-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 coatings SiOx (glass) coating (Glaskin) AlOx aluminum oxide coating carbon coating (DLC and Actis) Exterior coatings and interior laminates epoxy-amine coating (Sealica and Bairocade) copolyester (Amosorb: interior layer) Nanocomposites extremely fine mineral additions Oct. 02, Dec-02, Interior and exterior coating refers to the use of the process for bottles.

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