| The most common
industry-wide sealant materials used are PVC
and polyolefin. These strong heat-resistant
mataerials come in rolls, tubes and bags.
PVC (poly
vinyl chloride) is the most common and cost-effective
shrink wrap film available. It is durable and
best suited for wrapping individual products.
This film shrinks at low temperature and works
well with heat guns. PVC has a greater puncture
and tear resistance than polyolefin although
it is more brittle and less elastic. It produces
a strong odor when sealing and is not recommended
for food applications.
Polyolefin
is suitable for packaging food (It is FDA compliant
for direct food contact.) and bundling multiple
products. It is durable, elastic, and produces
little odor during the sealing process. Polyolefin
film shrinks at a higher temperatures than PVC
and performs best with most one step shrink
wrap machines, L-bar sealers and fully automatic
shrink wrappers.
Film rolls usually come in
two varieties: Single-wound is simply a single
layer wound onto a spool; centerfold is a double
layer folding method that allows wider shrink-wrap
to be wound onto a given size spool. The shrink-wrap
machine unfolds the material as it comes off
the spool. Film rolls are used in straight-bar,
L-bar, tunnel, heat gun, and mail bagging shrink
systems.
Shrink tubing is shrink material
folded and sealed down the longest open side,
forming a tube. It also comes in small one-piece
molded tubes used to cover wires, cables, and
connectors. It usually comes on a roll and used
in various shrink systems.
Shrink wrap bags can be two
pieces of shrink wrap material placed together
and sealed on three sides, a single piece folded
and sealed on two sides to form a pouch or bag,
or fully formed and ready for sealing with continuous
band sealers. Bags are available in various
gauges and used to package things like food,
various powders, herbs, and beverages.
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