Metallised film

Metallised films (or metalized films) are polymer films coated with a thin layer of metal, usually aluminium. They offer the glossy metallic appearance of an aluminium foil at a reduced weight and cost. Metallised films are widely used for decorative purposes and food packaging, and also for specialty applications including insulation and electronics.

Manufacture

Metallisation is performed using a physical vapour deposition process. Aluminium is the most common metal used for deposition, but other metals such as nickel or chromium are also used. The metal is heated and evaporated under vacuum. This condenses on the cold polymer film, which is unwound near the metal vapour source. This coating is much thinner than a metal foil could be made, in the range of 0.5 micrometres.^[1] This coating will not fade or discolour over time. While oriented polypropylene and polyethylene terephthalate (PET) are the most common films used for metallisation, nylon, polyethylene and cast polypropylene are also used.^[2]

Properties

Metallised films have a reflective silvery surface similar to aluminium foil and are highly flammable. The coating also reduces the permeability of the film to light, water and oxygen. The properties of the film remain, such as higher toughness, the ability to be heat sealed, and a lower density at a lower cost than an aluminium foil. This gives metallised films some advantages over aluminium foil and aluminium foil laminates. It was thought that metallised films would become a replacement for aluminium foil laminates, but current films still cannot match the barrier properties of foil. Some very high barrier metallised films are available using EVOH, but are not yet cost effective against foil laminates.^[3]

Table 1. Comparison of Metallised PET and aluminium foil

	Moisture (g/m².day)	Oxygen (mL/m².day)	UV light (%transmittance)
PET film, 12.7μm ^[1]	31	465	91
Metallised PET ^[1]	0.8	1.2	5
Aluminium foil 6μm^[4]	0	0	0

Uses

Decoration

Metallised films used for balloons

Metallised films were first used for decorative purposes as Christmas tinsel,^[1] and continue to be used for items such as wrappers and ribbons. The metallic helium filled novelty balloons given as gifts are made of metallised BoPET and often called Mylar balloons commercially.

Packaging

Both metallised PET and PP have replaced foil laminates for products such as snack foods, coffee and candy, which do not require the superior barrier of aluminium foil. Metallised nylon and polyethylene are used in the meat export market. The controlled permeation extends shelf life.

Metallised films are used as a susceptor for cooking in microwave ovens. An example is a microwave popcorn bag.

Many food items are also packaged using metallised films for appearance only, as these produce a package with greater sparkle when compared to competing products that use printed paper or polymer films.

Insulation

Metallised PET films are used in NASA's spacesuits to make them radiation resistant and keep astronauts warm, and in proximity (aluminised) suits are used by AR-FF fire fighters for protection from the high amount of heat released from fuel fires. Silvered emergency blankets are also used to conserve a shock victim's body heat. These reflective materials might also be used as part of industrial and commercial insulation (for example, insulated shipping containers).

Insulating blankets made with metallised PET were also used as insulation in aircraft until safety concerns resulted in their deprecation.^[5] In particular, it was found to be a major contributor to the in-flight fire of Swissair Flight 111 on September 2, 1998.^[6]

Electronics

Metallised films are used as a dielectric in the manufacture of a type of capacitor used in electronic circuits, and as a material in some types of antistatic bags.

Tragedies

The inflammable nature of Metallised PET led to the deaths of 229 people aboard Swissair Flight 111^[7] off Nova Scotia Canada.

References

1 2 3 4 Hanlon, J. (1992). 1st ed. Handbook of Package Engineering, Lancaster, PA, Technomic Publishing: ISBN 0-87762-924-2. Chapter 4 Coatings and Laminations
↑ Mount, E. (2004) Metalized Films for Food Packaging, Converting Magazine vol 3
↑ Mount, E. (2002) Metalized Film Barriers: Where to Next? Converting Magazine vol 3
↑ European Aluminium Foil Association
↑ "Airworthiness Directive". FAA.
↑ "Swissair to replace controversial Mylar insulation". CBC. 1999-11-09. Retrieved 2009-06-19.
↑ AirCrash Investigation 2016 (2016-11-14), Air Crash Disaster Over Swissair Flight 111 (ICAO: SR111, SWR111), retrieved 2016-12-01

Packaging
General topics	Active packaging Child-resistant packaging Contract packager Disposable food packaging Food packaging Luxury packaging Modified atmosphere/modified humidity packaging Package pilferage Package testing Packaging engineering Pharmaceutical packaging Reusable packaging Shelf life Sustainable packaging Tamper-evident Tamper resistance Wrap rage
Containers	Aerosol Container Aluminium bottle Aluminum can Ampoule Antistatic bag Bag-in-box Bags and flexible containers Barrel Beer bottle Biodegradable bag Blister pack Boil-in-Bag Bottle Box Bulk box Carboy Carton Chub Clamshell Corrugated box design Crate Disposable cup Drum Envelope Flexible intermediate bulk container Foam food container Folding carton Glass bottle Growler Insulated shipping container Intermediate bulk container Jar Jerrycan Jug Juicebox Keg Multi-pack Oyster pail Packet (container) Padded mailer Pail Paper bag Paper sack Plastic bag Plastic bottle Popcorn bag Retort pouch Sachet Security bag Self-heating can Self-heating food packaging Shipping container Skin pack Spray bottle Tin can Tube Unit load Vial Wooden box
Materials and components	Adhesive Aluminium foil Bioplastic Biodegradable plastic BoPET Bubble wrap Bung Cellophane Closure Coated paper Coating Corrugated fiberboard Corrugated plastic Cushioning Desiccant Double seam Foam peanut Glass Hot-melt adhesive Kraft paper Label Linear low-density polyethylene Liquid packaging board Low-density polyethylene Metallised film Modified atmosphere Molded pulp Nonwoven fabric Overwrap Oxygen scavenger Packaging gas Pallet Paper Paper pallet Paperboard Plastic film Plastic pallet Plastic wrap Polyester Polyethylene Polypropylene Pressure-sensitive tape Screw cap Screw cap (wine) Security printing Security seal Shock detector Shock and vibration data logger Shrink wrap Slip sheet Staple (fastener) Strapping Stretch wrap Susceptor Tear tape Temperature data logger Time temperature indicator Tinplate Velostat
Processes	Aseptic processing Authentication Automatic identification and data capture Blow fill seal Blow molding Calendering Canning Coating Containerization Curtain Coating Die cutting Die forming (plastics) Electronic article surveillance Extrusion Extrusion coating Glass production Graphic design HACCP Hermetic seal Induction sealing Injection molding Laminating Laser cutting Molding Papermaking Plastic welding Plastics extrusion Printing Quality assurance Radio-frequency identification Roll slitting Shearing (manufacturing) Thermoforming Track and trace Vacuum forming Ultrasonic welding Vacuum packaging Verification and validation
Machinery	Barcode printer Barcode reader Bottling line Calender Can seamer Cartoning machine Case sealer Check weigher Conveyor system Extended core stretch wrapper Filler Heat gun Heat sealer Industrial robot Injection molding machine Label printer applicator Lineshaft roller conveyor Logistics automation Material handling equipment Mechanical brake stretch wrapper Multihead weigher Orbital stretch wrapping Palletizer Rotary wheel blow molding systems Shrink tunnel Staple gun Tape dispenser Turntable stretch wrapper Vertical form fill sealing machine
Environment, post-use	Biodegradation Environmental engineering Glass recycling Industrial ecology Life-cycle assessment Litter Paper recycling Plastic recycling Recycling Reusable packaging Reverse logistics Source reduction Sustainable packaging Waste management

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