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7/27/2019 Barrier Sheets - Rajoo
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TH E EC ON OM IC TI ME S POLYMERS AUGUST - SEPTEMBER, 2008 19
Barrier Packaging:
C O V E R S T O R YC O V E R S T O R YFOCUS
Barrier Packaging:Essential for theRetail Success
The growing need for such thermoformable
barrier sheets can not be ignored. Organised
retail is here to stay and flourish. If such
materials are not offered by the local industry,
nothing stops the organised retail chains from
importing them from their current sources
anywhere in the world.Sunil JainPresident, Rajoo Engineers, New Delhi
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CMYK
Introduction
Concept of barrier packaging
materials is yet to gain momentum
in India the way it should have. The
variety in cuisines is as diverse as
the country and its people. Indians,
unlike many other Asians, still prefer
fresh food over frozen or pre-cooked food. With rising disposable
incomes and DINK households
(Double Income No Kids), cooking
meals at home is taking the back
burner or for that matter no burner at
all! And this is precisely the reason, why
the demand for high barrier packaging
materials for packaging of food is poised to
rise in the country to stupendous volumes in
days to come.
Barrier films were first introduced in the
country for packing of long shelf-life edible
oil. It took ages for this concept to be both
technically and commercially viable. The fact,
however, remains that it is now a success.
Thanks to the perseverance of the flexible
packaging material producers, FFS machine
manufacturers and of-course, the edible oil
producers.
The market for barrier films and sheets
for packaging of ready-to-eat or pre-cooked
food will surely not witness such prolonged
efforts and as a concept, it is already accepted.
Thanks also to the rev olution of the
organised retail and also the availability of
the packaging materials. It was always
understood that such materials are only forpacking of meat as happens in the Western
and meat-eating countries but the scenario
has changed and the advantages of using
such materials even for vegetarian food is
now being understood and accepted.
Barrier Packaging Materials
Edible products need any or more than one
of the following packaging materials:
Films for use on FFS machines for solid
and liquid products
Rigid thermoformed containers packedon FFS machines (with in-line
thermoforming) or off-line packing inpreformed containers
Rigid retortable high temperatureresistance thermoformed containers
In this contribution, focus will be on the
latter i.e. thermoformable barrier multilayered
sheet for shelf stable rigid containers. Further,
retortable shelf stable barrier plastics offer aunique packaging concept on autoclaveable,
reheatable and microwaveable plastic
containers with outstanding performances
on sensory and nutritive characteristics, a high
abuse container resistance together with an
attractive presentation.
Therm ofo rme d con tai ner s of barri ermaterials consist of two components lidding
material and the container itself. The food
product needs protection both, from the top
and the bottom, to attain the required shelf-
life. While the top lidding is produced on 5-7
layer blown film lines or from composite
laminates, the bottom container is produced
from 5-7 layer barrier sheets and then
thermoformed in-line or off-line.
Thermoformable bar rie r sheets have low
oxygen or moisture transmission. They also
help in preserving the aroma and odour.
Such sheets not only offer barrier andchemical resistance properties, they can also
be formed into many unique and generic
shapes. Containers from barrier
thermoformable sheets can also be hot
filled.
Applications
Any product which is highly susceptible tooxidation or turns rancid or is not edible over
a period of time, requires to be protected from
the vagaries of nature and exposure on the
retail market shelves. Some of those
Retortable shelf stable
barrier plastics offer a
unique packaging
concept on
autoclaveable,
reheatable and
microwaveable plastic
containers with
outstanding
performances on
sensory and nutritive
characteristics, a high
abuse container
resistance together
with an attractive
presentation.
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categories of products are:
Dry fruits Dairy products Ready-to-eat food with curries Frozen food Ready-to-eat full meals
Soups Sauces and chutneys Baby food
The advantage of opting for
thermoformable sheets is that any shape of
container can be formed.
Materials
The bulk layer of the co-extr uded
sheet is one of the so called mass
polymers, which are mostly
polystyrene (PS) or
polypropylene (PP), from
which PS is the most
preferred one because of
the ease of
thermoformabil ity
that is necessary on
Form-Fill-Seal lines.
The use of PP is
however, a
necessity for
t h o s e
a p p l i c a t i o n s
where high
t e m p e r a t u r e
resistance is
required forretorting. Barrier is
imparted by using
Nylon, PVDC or
EVOH.
The barrier sheet is
produced from any or a
combination of the
following materials:
PE PP Nylon EVOH
PVDC Tie resin PS
The barrier sheet can have either of the
following configurations depending on the
final properties required:
ABA ABAC CABA
Retortable trays from RexhamShelf stable food from Rexham Retortable bowls from Rexham
PS/EVOH/PS High barrier sheet - for Preserves,
miniportions of cream for coffee, milk-based
desserts, Suitable for modified atmosphere
packagin g (MAP). - Coexpan
PS/EVOH/PE High barrier sheet for, fresh or
cured cheese, sauces, fruit juice, compact sweets,
fresh desserts - Suitable for modified atmosphere
packagi ng (MAP).- Coexpan
PS/PE/PS Medium barrier for
Frozen foods, jellies, milk-based
desserts, ice cream, pizzas, fresh
cheese...- Coexpan
PP/EVOH/PP- High barrier for Meat products
subjected to autoclave, cooked dishes, cooked
meats, long-life fresh pasta, fruit preserves,
sauces, pt...Suitable for modified atmosphere
packagi ng (MAP).- Coexpan
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CMYK
CABAC ABCBD
Typical barrier sheets contain either nylon
or EVOH as the barrier layer e.g. PP/CXA/Nylon
or EVOH/CXA/PP. It is necessary to use PP or
PS to impart thermoformability to the sheet.
Total thickness ranges from 300 microns to1.5 mm depending on the size and depth of
the final container.
For certain dairy products stored in the
chilled chain cabinet, additional techniquesand procedures are employed to extend the
shelf-life of such food. A typical example being
certain kinds of cheese and curd, and a CO2/
Nitrogen mixture and a PS/Barrier/PE
material.
Sheet Line
Typ ical setup of a bar rie r she et lin e is as
follows:
4/5 extruders. Conveying and gravimetric feeding
system.
Desiccant dryers. Cassette type / continuous screen
changers.
Melt metering pumps.
Melt pressure and temperaturetransducers.
Co-extrusion feed block. Flat sheet die with trolley. Three-roll inclined polishing roll stack. Trim station with rotary cutter. Trim grinding and collecting unit. Circulating fluid temperature control unit. Take off unit. Two-station centre winder.
Conclusion
Today, as a supplier of pack aging material
based on plastics, no contribution can becomplete without addressing the
environment issue. In general, multilayered
plastic products are more difficult to
recycle if heat sensitve materials or
incompatible materials are coextruded. For
medium and high barrier sheet extrusions,
it is necessary to emphasize that the plastic
sheets are all based on a major part of a
bulk material (PS or PP) and therefore
incompatibility upon recycling is not a
major issue. In addition, thermal stability
of all the components will not intefereThree roll inclined polishing stacker
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TH E EC ON OM IC TI ME S POLYMERS AUGUST - SEPTEMBER, 2008 23
where specific techniques need to be used.
Th er fo re , co extr ud ed st ru ct ur es ca n be
integrated in the recycling systems and
will contribute to optimal reutilisation of
materials.
The gro win g need for such
thermoformable barrier sheets can not be
ignored. Organised retail is here to stay and
flourish. If such materials are not offered bythe local industry, nothing stops theorganised retail chains from importing them
from their current sources anywhere in the
world.
Extruders typical 4 extruder five layer configuration
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TECHNICAL CONTRIBUTIONS
The Economic Times Polymers
Times B2B, Bennett, Colemen & Co Ltd, The Times of India Building, Dr D.N. Road, Fort, Mumbai : 400 001.
Tel: 24980271 Ext. 140 E-mail: b2bads@timesgroup.com
Two station winder
under normal processing conditions,
excluding the PVDC containing materials
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