Paper as a substitute to plastic films in flexible packaging

By C A S Chidambara Vinayagam

ITC Limited – Paperboards and Specialty Papers Division

Flexible Packaging What is Flexible Packaging: A non rigid packaging structure, whose shape can be easily changed .

The construction is generally made of plastic films, Al foil, paper or any combination of these. But

dominated by Plastic films of very thin thickness ( as low as 10 um)

Common examples : bags, pouches, labels/wraps, lidding, shrink sleeves and stretch film.

Characteristics of Flexible Packaging• Generally printed with Gravure or Flexographic process

• Dominated by plastic films of thin gauges.

• Low cost and barrier properties can be achieved by combining films of different polymers

• Occupies very low space in the retail market but has good graphics to attract the customers attention.

• Predominantly from non renewable source and price linked to crude

• Main problem • Excessive use is causing littering and poor collection for recycling

• Generally non biodegradable and compostable

• Causing land and marine pollution.

Government and Corporate Commitments to Reduce and Eliminate Plastics

India will abolish all single-use

plastic by 2022, vows Narendra

Modi

We, at Tata Power are determined to strengthen our

Club Enerji programme and reach out to a global

audience by encouraging the online audiences of today

to become responsible citizens of tomorrow. Our latest

online module on “Say No to Plastic” is aimed at

making children realise the importance of eradicating the

use of plastic and conserving our environment.

The problem of solid waste management is one of epic

proportions and requires each organ of society and,

more so, enterprises that are large economic organs of

the society, to make a meaningful contribution towards

this, in line with the Prime Minister’s path breaking

initiative of Swachh Bharat.

- Mr Sanjiv Puri

“

“

Today’s ineffective plastics economy is the result of

decades of highly fragmented, uncoordinated and

incremental innovation, which hasn’t been able to move

the needle on economic value loss and negative

externalities.- Global Plastics Protocol

”

”

Country will also introduce a campaign against marine

litter and a pledge to make 100 national monuments litter-

free

- Mr. Praveer Sinha,

CEO & Managing Director,

Tata Power 2

European consumers attitude to packaging structures

Image Source : www. Procarton.com

The advantage of paper based packaging

Image Source : www. Procarton.com

Can Packaging affect the Brand Value

Image Source : www. Procarton.com

What consumers want in Packaging and ready

Image Source : www. Procarton.com

Challenges and opportunity for paper based structures

Challenges

• Highly porous and poor barrier

• Not enough strength to match the requirements of the packaging

• Actions to improve printability will reduce strength

• Not glossy and transparent

• May not be economical till it reaches a critical mass.

Opportunities

• Renewable and environment friendly

• Advancements in processes to improve printability and strength

• Developments in coatings and chemicals to give barrier

• Environmental and regulatory pressures to shift to paper packaging

• Consumers attitude to packaging shifting towards paper

Advancements to Improve printability and runnability

• Paper surfaces need to match the printability requirements for reproduction through gravure and flexo with good gloss – need for a low PPS paper.

• Advances in • Coating Technology through curtain coaters

• Rheology modifiers to improve coating colour solids at lower viscosity

• Advancements in structure of pigments to suit the end use

• Calendering operations like soft nip and brush calendering• improve gloss and smoothness without compromising strength

Curtain Coating

• A layer of coating colour like a curtain is ejected out of coating die and is applied on the paper surface.

• Similar to extrusion coating of Polymers

• Has good coverage and uniform coverage and Brightness

• PPS may be inferior to Blade Coating

Image courtesy www. Valmet.com

Curtain Coating – Multilayer Curtain Coater Vs Single Layer

Multilayer curtain coater : coating slide die has

expandable designs which give possibility to

upgrade by adding coating layers.

• Coating thickness from extremely thin to thick

• Uniform layers simultaneously all within one

coating station.

• Can be fixed in machines on a wide range of

speeds and widths.

• coating of different formulations provides wide

range of product developments to suit different

applications.

Image courtesy www. Valmet.com

Gloss and other surface treatments

• Softnip Calender• Preserves Bulk

• Improves the gloss and smoothness

• Improves varnish and ink Hold out

• Reduces thickness variations

• Brush Calendering• Rolls covered with fine fabric gives polishing like action.

• Improves gloss and ink hold out

• Not much improvement in smoothness

Improving Tensile Strength • Paper is anisotropic in nature.

• Its elastic properties are very low.• Typical stretch values are in the range of 4 – 7 % where as polymeric films have stretch

as high 400 %

• Tensile energy absorption need to be higher to prevent the packaging bursting out when impacted

• Stronger fibres and refining improves strength • Cylindrical refining

• High consistency refining

image courtesy :www.andritz.cIom

Improving strength Clupak Technology : Creeps the paper under a stretched rubber blanket and nip bar.Improves stretch and Tensile energy absorption in the paper.Papers with such properties are used for packing cement , sugar and food grains

Image courtesy : www. Cepi.org.

Impact on strain at different recoiling % of Rubber blanket .

Specific Stress strain curves for different Rubber Recoiling percentages

Image courtesy : www. Cepi.org.

Imparting Barrier to the paper

• Packaging need to preserve the characteristic of the product which are packed inside till it reaches the consumer.

• So need for a strong barrier as the external conditions vary widely and when the product is exported it changes even more.

• Imparting barrier without compromising • Sustainability

• Food Grade compatibility

• Organoleptic properties.

Barrier Requirements

• Water and wet resistance

• Oil and Grease resistance

• Water Vapour transmission resistance

• Oxygen transmission rate

• Resistance to light

• Resistance to Biological agents

Barriers which are already crossed

• Oil and Grease resistance , Wet resistance• Through Water Based Emulsion coatings and other chemicals.

• Through Bio based and compostable plastic coatings

• Resistance to micro organism• Through Fungicide Coatings

Barriers for which development is underway

• Oxygen transmission Rate • Through Xylane coatings

• Through Nano coatings

• Water Vapour Transmission rate • Emulsion Coatings

• Nano Cellulose and nano pigment coatings

• All the above developments are taking time as a sustainable solution is not reached yet.

Final solution • A fine paper

• Coated with modern technologies suitable for high speed gravure printing

• Enhanced strength through clupak technology

• With good barrier through specialty coatings or nano coatings

Can possibly replace plastics offering sustainable solution.

Do such papers available today ?

Extensible sackraft paper from Mondi and Billerud used in packing cements and rice flour in Europe

Paper laminates are used in Gutka and tobacco packaging today

Thank You