Define lamination:
combine different plastic film materials (+ non plastic materials) => 1 material
2+ layers (at least 1 is plastic)
Purpose of lamination:
COMBINE properties of materials (mechanical properties, barrier, heat-sealing, printability, optical properties, stretch…)
What products usually use laminates for packaging? (3)
long shelf-life
$$$$ products (high profit margin)
sensitive products
methods of making laminates: (4)
adhesive lamination
extrusion coating
co-extrusion
vacuum metallization
What is the process of adhesive lamination? (4)
adhesive (solvent or water based) applied to one web
Cured (dried)
combine with uncoated web (heat + pressure)
continue until all layers complete
Adhesives can be ____ or ____ based
aqueous, solvent
Why is curing important in adhesive lamination?
dries; excess solvent can cause de-lamination
parts of the adhesive lamination machine: (3)
unwind/rewind rolls
adhesive applicator
nip and chill roller
____ coating is comon with PE, PP, PET paper
extrusion coating
What are advantages of extrusion coating vs adhesive lamination? (4)
What acts as the ‘glue’ in extrusion coating?
extrudate
What is co-extrusion?
2+ extrusion feeders into 1 head -> extrudate is combination
Advantages of co-extrusion: (3)
lower cost
less delamination
flexibility
What are some products obtained with co-extrusion?
thermoforming films/sheets, retortable films/sheets, flexible films
What is vacuum metallization?
metallized plastic film/paper (added metal material)
properties of metallized films: (4)
reflectance (metallic/shiny)
tougher
susceptor (microwave energy -> radiant heat)
better barrier
Pre-treatments required before vacuum metallization: (2)
mechanical treatment
primer coating
What is the mechanical treatment for vacuum metallization?
high voltage/frequency discharge
Corona (continuous arc) @ film surface -> introduce polar groups
-> clean, oxidize, activate surface = better adhesion
What is the ‘primer coating’ in vacuum metallization?
thin coat applied that attracts both layers (better adhesion)
What is the process for vacuum metallization? (3)
BATCH PROCESS:
What films are used for vacuum metallization? (4)
PP (80%)
PET (15%)
PA (4%)
PVC, PVDC, PS (1%)
T/F: the most common plastic film in metallization is PS
FALSE: Least common (<1%)
What are the functions of various laminate layers? (inside -> outside) (5)
product compatibility heat sealability barrier mech. structure printability/abrasion resistance
Describe the laminated structure of a juice box (out -> in) (5)