Barrier Sheets - Rajoo

7/27/2019 Barrier Sheets - Rajoo

1/5

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


2/5

20 TH E EC ON OM IC TI ME S POLYMERS AUGUST - SEPTEMBER, 2008

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.


3/5


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


4/5

22 TH E EC ON OM IC TI ME S POLYMERS AUGUST - SEPTEMBER, 2008

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


5/5


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

We solicit your Technical Editorial Contributions by the way of Case Studies associatedwith a unique application, project or set-up. Adaptation to a new technology or process could

also be the basis of your article.

Please send in your articles, which could be considered for publication after evaluation.

We request you to send it in duplicate along with detailed diagrams, photographs, sketches, tables etc.

Kindly send us a soft copy for the text matter.

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: [email protected]

Two station winder

under normal processing conditions,

excluding the PVDC containing materials

Documents

Barrier Sheets - Rajoo