1.Why
are there so many packaging film models?
Because there are so many chemically different types of product
to be packaged! MonoSol packaging films are formulated in different
ways - the PVOH resin, plasticizer system and other ingredients
vary and provide a range of films with different product compatibility
characteristics. One (or more) is likely to be suited to your product
- the correct film grade may be easily predictable or compatibility
testing with a number of films may be required.
2.Is PVOH film
biodegradable?
Yes - over 50 species of microorganisms (bacteria, yeast and molds)
typically found in compost, soil and activated sludge wastewater
treatment facilities will degrade PVOH. PVOH film will totally biodegrade
when composted and, when solubilized, is rapidly degraded and assimilated
by a number of acclimated microorganisms in waste water streams.
Conventional waste water treatment process conditions will acclimate
activated sludge microorganisms to polyvinyl alcohol.
3.How does humidity
affect PVOH film?
Polyvinyl alcohol is a hydrophilic polymer and the plasticizers
used in film manufacture also have an affinity for water - PVOH
will absorb moisture from a humid atmosphere and give up moisture
to a dry atmosphere. As moisture content increases with humidity,
the film will tend to become softer and more elastic, losing tensile
properties and increasing in ultimate elongation. Also, the coefficient
of friction will increase. Under these conditions, machining can
become difficult and it is advisable to control ambient conditions
when converting PVOH film.
4.Is PVOH film
printable?
Yes - PVOH film readily accepts both water-soluble and solvent-based
inks without the need for surface treatment. Conventional printing
processes may be used. For most packaging applications requiring
water solubility, water-based inks are preferred because they will
rapidly solubilize or disperse. The Greensol "WS Easy Print"
system is a low cost flexographic printing unit which can be fitted
to VFFS packaging machines to facilitate the in-line printing of
PVOH film.
5.Can liquid
be packaged in water soluble film?
Yes - polyvinyl alcohol is resistant to nearly all organic solvents,
other organic liquid and mineral oil. However, moisture and plasticizers
can be leached from the film by liquid formulations (causing embrittlement)
and certain organic liquid can cause film insolubility or migrate
through the film even though they have no solvent action on PVOH.
Therefore, compatibility testing should always be performed. Although
water is the best solvent for polyvinyl alcohol, PVOH film can be
used to package liquid formulations having a low water content -
a few percent is optimal and often beneficial to the maintenance
of film flexibility.
6.When
PVOH dissolves in water, what form is it in? Does it eventually
disappear completely?
When film dissolves, it breaks down to its smallest components,
which are invisible polymer chains. Microorganisms in waste water
streams feed on these large molecules and break them down to carbon
dioxide and water. PVOH polymer is thus completely biodegradable.
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