By Leo and Daniel Luetzelschwab

SMART- PETG

PETG films have been used for more than ten years in the plastic card industry. The applications and the requirements have been changed as a result of the increasing demand for multi-functional and high security cards and documents. Due to the High Tech Co-extrusion process it was possible to tailor make specifications which meet the new market requirements. The newest challenge was to combine PETG with Polycarbonate to get new products at reasonable prices. This marriage of PETG with PC shows the long-awaited combination of added strengths.

The PET Family (generic term: polyester) is divided in two main types. The first type is Semi-crystalline A-PET (Polycondensation product between Ethylene Glycol and Terephthalic acid) = Poly-Ethylene-Terephthalate, PET. The second type is Amorphous PETG (Co-polycondensation product between Ethylene Glycol/Cyclo-hexandimethanol and Terephthalicacid) = Copolyester. The “G“ in the term PETG indicates the use of a second glycol in the process. PET films have already been used for a very long time in large quantities in the packaging industry for transparent boxes, trays, thermoformed containers and more recently for beverage bottles.

Reasons for using PETG for plastic cards; a wide range of innovations and tailor-made specifications thanks to the co-extrusion process, high mechanical strength and excellent flex tests with PETG and the wide spectrum of card applications can be made. Finally and more important are ecological considerations since PETG is environmentally friendly, i.e., chlorine is not used.

The bar chart above shows as an overview the main characteristics of PETG films with a value. Note scale e.g. low temperature resistance, moderate laser engraving, moderate shelf life, low/moderate pricing, very good processing properties.

Ecological Considerations
The most professional and objective way to compare and assess materials used in the market is a comparison of the Ecoprofiles. The Swiss Federal Laboratories for Materials Testing and Research (EMPA) is a worldwide respected institute with excellent competence and reputation also in the subject of Ecoprofiles. Such Ecoprofiles (Life-Cycle Assessment, LCA) contain three main segments for a complete life-cycle (from cradle to grave); production phase, use phase and disposal phase.

Three main reasons for thermal processing / incineration:

• Chemical reactive waste will be converted into inert harmless materials.
• Achieve distinctive volume reduction.
• Save primary energy by burning waste and apply energy recovery.

In Municipal Solid Waste Incineration (MSWI) PETG does not cause any ecological problems. Any chlorine containing products produce and release dioxins (very toxic substances). To comply with clean air legislation passed by the parliaments and governments all over the world, dioxin abatement requires very sophisticated, thus very expensive filter equipment be installed in the waste incineration plants. As a rule for consumer products formerly made of PVC there is now a substitute; e.g. the typical beverage container for soft drinks and mineral water in the past was the PVC bottle; nowadays, the bottle is made of PET which, when burnt in waste incineration plants, does not harm the environment.

Ecoprofiles are powerful tools for assessing environmental burdens. In rapidly increasing consumer applications, typically with short lifetimes, like plastic cards, PETG or other non-chlorine containing products are the preferred materials. Whereas PVC is a more suitable material for applications in investment goods, typically with long life times, for example window frames.

Market needs
The plastic card market today is characterized by continuous, rapid and almost unpredictable changes. Four mainstream trends are convenience, functionality, security and environment.

Customers asking for Convenience and Functionality
• More comfort and easier to handle (also contactless cards) Payment and/or access to
– Parking
– Public/private transportation busses, railways
– Highways
– Resorts
– Pre-paid scratch phone cards
– Gift cards

• Multi-purpose for high-tech applications:
– ID card
– Passport
– Driver licenses
– Health care card (medical records)
– e-based activities, e-commerce

Security
• Extreme growing need for security also due to increase of multiple functions cards
• Confidence-building to maintain and increase card users and receivers trust
• Digital printing
• Cryptographic
– 2D or random bar code
– Cryptographic encoding through numerical mathematics
• Biometric features (finger print, iris scan)

Product line for PETG films

Overlay transparent, clear:
Thickness 95 to 150 microns with:
• Release (type 4700)
• Release and laser (type 4600)
• Heat seal coating on one side to give an excellent bond against printed Corefilms, with full color, bleed printing or UV curing inks.
• Five-layers coextruded Overlay with the additive «HTR» (High Temperature Resistant) in the middle Iayer, to give higher temperature resistance, longer shelf life and allows a top quality embossing (type 64700, 64600)

Corefilms white opaque:
Thickness 100 to 800 microns with:
• Bluish white or yellow white opaque
• Ti02 content 6 percent up to 15 percent
• With release on the outer layers for pre-lamination for card bodies
• Five-layers coextruded Corefilm with the additive HMS (High Mechanical Strength) type 8411

Partner PC
Polycarbonate films have been used for many years for various applications, mainly for long shelf life smart cards with high laser engraving quality.

Based on the bar chart above, we show as an overview the main characteristics of PC films with a value Note Scale e.g. high temperature resistance, very good laser engraving, good shelf life, high price level, difficult/moderate processing properties, etc.

Marriage: PETG + PC = PEC
Due to high developed Coextrusion technology it is possible to combine PETG with Polycarbonate to get new products which combine the advantages of PETG and compensate their weakness with the characteristics and strengths of Polycarbonate.
As you can see on the following bar chart the main characteristics of PETG and PC films are married i.e. both partners can bring in their strengths.

Conclusion
PETG is an excellent polymer for plastic cards showing a broad bundle of impressive strengths, and the same is true for PC; the two polymers are complementary to each other. Thus, an ideal material for plastic cards and security documents would be the combination of both their strengths. The marriage of PETG with PC shows this combination of added strengths. This achievement without any disadvantages is indeed the non plus ultra material for today’s plastic card manufacturing.

About the Authors: Luetzelschwab Consulting Ltd. is Partner of Folienwerk Wolfen for more than ten years for marketing and sale of all kinds of PETG- and PEC-films for plastic cards and security documents all over the world. Folienwerk WOLFEN GmbH a producer of PETG- and PEC-films in Europe for the plastic card and security document industry. At the beginning of 2005 Wolfen made an investment of a new co-extrusion line which can produce high tech products like PETG / PC / PETG and also single PC films for ID-cards, e-passports and other high security documents. Web site: www.smart-petg.com.