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.