Laminates Flashcards
objectives of lamination
combine properties mechanical barriers heat sealing optical printability stretch machinability
use of laminate to
long shelf life
high profit product
very sensitive product
method of lamination
adhesive lamination
extrusion coating
co-extrusion
vacuum metallization
adhesive lamination
adhesive applied to one web combined with other
solvent or water based type values with heat requirements, bond strength
it is cured = dried = because excess solvent cause delamination
coated web combined with uncoated using pressure/heat
process continues until laminate complete
extrusion coating
with PE, PP, PET, paper advantages - handling thin PE difficult - Extrusion Temperature impregnate plastic onto paper - cheap - less pollution need pretreatment for foil extradite acts as a glue
co-extrusion
two or more extrusion feeders
low cost
less delamination
flexiblility
vacuum metallization
metallized films
- reflectance, metallic look, attractive
- tough
- converts mw NRJ into radiant heat = susceptor
good barrier to moisture, flavor, light, gaz
pretreatment before vacuum = mechanical treatment = high voltage and high frequency and corona generates film surface by introducing polar groups
metal is vaporized in vacuum chamber
coated with varnish to seal, smooth surface
functionality of laminate layer
print/abraison resistance mechanical structure barrier heat sealability product compatibility
example juice box
PE = outer protection
printed paper
PE = improves puncture resistance of foil
foil = excellent barrier to moisture and flavor
PE = improves foil heat sealibility
heat seal
depends on melt T, machine P, contact time
desirable = low melt T, strong seal, low cost
common heat seal = LDPE (low T fast seal), EVA (ethylene vinyl acetate), Ionomer like surlyn (seals through crumbs grease)
barriers
nylon = outer often = poor water, high gaz barrier
LDPE = heat sealing barrier
PVDC = excellent water/gaz barrier
LDPE + ionomer = coextruded heat sealing layer
OP = breathable layer = high water barrier low gaz barrier
types of composite cans
convolute wind
spiral wind
linear draw
single wrap
design variations
shape size paperboard and body layers opening and closing systems label
function of paper layer in can body
strength structure printability Kraft recylced
function of PE layer in can body
protect paper form moisture, tear, scratches
heat seal other layers
barrier to moisture (low gaz barrier)
