Guardian is the trademark name of a polymer originally manufactured by Securency International, a joint venture between the Reserve Bank of Australia and Innovia Films Ltd. The latter completed acquisition of the former's stake in 2013.
Its production involves gravity feeding a molten polymer, composed of extruded polypropylene and other polyolefins, through a four-storey chamber. This creates sheets of the substrate used as the base material by many central banks in the printing of polymer banknotes.
Production
Polypropylene is processed to create pellets. These pellets are extruded from a core extruder in conjunction with polyolefin pellets from two "skin layer" extruders, and are combined into a molten polymer. This consists of a 37.5μm thick polypropylene sheet sandwiched between two 0.1 μm polyolefin sheets, creating a thin film 37.7 μm thick.
The molten polymer undergoes snap cooling as it passes by gravity feeding through a brass mandrel, which imparts on the thin film many properties, including its transparency. The cast tube material is then reheated and blown into a large bubble using air pressure and temperature. At the base of the four-storey chamber convergence rollers collapse the tube into a flat sheet consisting of two layers of the thin film. This creates the base biaxially-oriented polypropylene substrate of 75.4 μm thickness, called ClarityC by Innovia Films.
The base substrate is slit as it exits the convergence rollers. Four 3-micrometre (0.00012 in) thick layers of (usually white) opacifier are applied to the substrate, two on the upper surface and two on the lower surface. A mask prevents the deposition of the opacifier on parts of the substrate that are intended to remain transparent. These overcoat layers protect the substrate from soiling and impart on it its characteristic texture, and increase the overall thickness to 87.5 μm. The resulting product is the Guardian substrate.
The opacifier conversion phase involves the use of resin and solvents, creating volatile organic compounds (VOCs) as by-products that are combusted in a thermal oxidizer. The resulting polymer substrate then passes through a rotary printing press using chrome-plated copper cylinders. After printing, the holographic security foil is incorporated into the base substrate. This is then cut into sheets and transported to the banknote printing companies in wooden boxes as a secure shipment.
Properties
Guardian is a non-porous and non-fibrous substrate. Because of this, it is "impervious to water and other liquids", and so remains clean for longer than a paper substrate. It is difficult to initiate a tear on the substrate, which has higher tear initiation resistance than paper.
Polymer banknotes
Guardian is used in the printing of polymer banknotes by many central banks.
It is the base material used for currencies printed by:
In 1993, the Bank of Indonesia issued a commemorative Rp 50,000 banknote and the Central Bank of Kuwait issued a د.ك1 banknote. In 1998, the Bank Negara Malaysia issued a commemorative RM50 banknote, and the Central Bank of Sri Lanka issued a commemorative Rs200 banknote. In 1999, the Northern Bank of Northern Ireland issued a commemorative £5 banknote, and the Central Bank of the Republic of China in Taiwan issued a commemorative NT$50 banknote. In 2000, the Central Bank of Brazil issued a commemorative R$10 banknote and the People's Bank of China issued a commemorative ¥100 banknote. In 2001, the Central Bank of Solomon Islands issued a commemorative SI$2 banknote. In 2009, the Bank of Mexico issued a commemorative $100 banknote.
Notes
- de Heij 2002, p. 6.
- ^ Garoffolo & Sientek 2009, p. 25.
- ^ Hardwick & Ghioghiu 2004, p. 6.
- ^ Innovia Security 2013.
- ^ Bank of Canada: Life Cycle Assessment of Canada's Polymer Bank Notes and Cotton-Paper Bank Notes 2011, p. 32.
- Hardwick & Ghioghiu 2004, p. 1.
- Hardwick & Ghioghiu 2004, p. 2.
- Robertson 2011.
- Eu, Chiew & Straus 2006, p. 26.
- Eu, Chiew & Straus 2006, p. 38.
- Eu, Chiew & Straus 2006, p. 46.
- Boesveld 2011.
- Eu, Chiew & Straus 2006, p. 54.
- ^ Innovia Security & October 2015.
- Eu, Chiew & Straus 2006, p. 60.
- Eu, Chiew & Straus 2006, p. 68.
- Eu, Chiew & Straus 2006, p. 72.
- Eu, Chiew & Straus 2006, p. 76.
- Eu, Chiew & Straus 2006, p. 80.
- Eu, Chiew & Straus 2006, p. 92.
- Eu, Chiew & Straus 2006, p. 98.
- Eu, Chiew & Straus 2006, p. 114.
- Eu, Chiew & Straus 2006, p. 116.
- Eu, Chiew & Straus 2006, p. 128.
- Eu, Chiew & Straus 2006, p. 134.
- Eu, Chiew & Straus 2006, p. 144.
- Eu, Chiew & Straus 2006, p. 124.
- Eu, Chiew & Straus 2006, p. 90.
- Eu, Chiew & Straus 2006, p. 126.
- Eu, Chiew & Straus 2006, p. 42.
- Eu, Chiew & Straus 2006, p. 122.
References
- Boesveld, Sarah (21 June 2011). "Graphic: Canada's new money is polymer in your pocket". National Post. Retrieved 21 November 2011.
- de Heij, Hans (May 2002), Durable banknotes: an overview (PDF)
- Eu, Peter; Chiew, Ben; Straus, Stane (2006). World Polymer Banknotes: A standard reference (2nd ed.). Eureka Metro. ISBN 9834303823.
- Garoffolo, Bruno; Sientek, Paul (April 2009). "Guardian technology starts with the film" (PDF). Billetaria. 3 (5). Cash and Issue Department, Bank of Spain: 25. Retrieved 9 March 2014.
- Hardwick, Bruee; Ghioghiu, Ana (2004). "Guardian substrate as an optical medium for security devices" (PDF). Note Printing Australia. Archived from the original (PDF) on 24 September 2015. Retrieved 8 March 2014.
- Robertson, Grant (3 December 2011). "Funny money: How counterfeiting led to a major overhaul of Canada's money". The Globe and Mail. Retrieved 8 March 2014.
- Life Cycle Assessment of Canada's Polymer Bank Notes and Cotton-Paper Bank Notes (PDF) (Report). PE Americas, Tryskele. Bank of Canada. 27 May 2011. Retrieved 6 March 2014.
{{cite report}}: CS1 maint: others (link) - "Guardian - Facts and figures". Innovia Security. 20 September 2013. Archived from the original on 13 October 2014. Retrieved 8 March 2014.
- "Guardian substrate issuers" (PDF). Innovia Security. October 2015. Retrieved 7 March 2016.
Further reading
- Guarner, Enrique (April 2009). "Polymer and the printing process" (PDF). Billetaria. 3 (5). Cash and Issue Department, Bank of Spain: 26–27. Retrieved 9 March 2014.