Mylar® 850

Product Description

Mylar® 850 is a co-extruded, one side heat sealable polyester film. It can be heat sealed to itself and heat seals well to thermoformed APET/CPET trays and APET coated board. It also heat seals to various other substrates including PVdC, PVC, paper and aluminium foil, but will not seal to polyolefines. The plain (non heat-sealable) surface of Mylar® 850 exhibits the properties of a standard polyester film. Mylar® 850 is available in thicknesses of 15, 20 and 30 micron.

Typical Applications

Mylar® 850 is an excellent film for lidding to APET/CPET trays, either as a single web (Fig.1) or as part of a laminate (Fig. 2). Such packages are often used for dual ovenable ready meals. Mylar® 850 can also be used on Form-Fill-Seal machines and blister packs; its excellent aroma barrier properties make it ideal for packaging aromatic products such as air fresheners and toilet blocks.

Practical Information

Mylar® 850 has an exceptionally wide heat seal range, from 140°C to 220°C, with outstanding hot tack properties. Either fin seals or overlap seals may be made on conventional packaging equipment. The sealable surface of Mylar® 850 also acts as an excellent 'prime' for water-based latices. The film can thus be PVdC coated from an aqueous dispersion by converters without a primer to produce a high barrier laminating film. The plain surface of Mylar® 850 can be printed or metallised in the same way as plain polyester film, although the sealable surface makes handling of the film during conversion more critical. Mylar® 850 can withstand temperatures down to -70ºC and food can be heated/cooked in this film at typical heating conditions of 220ºC for 30 minutes. The heat seal surface of the film is normally wound on the inside of the reel (Mylar® 850i).

Food Contact Advice

Mylar® 850 is compliant with European Union food contact legislation (Directive 2002/72/EC which is consolidated Directive 90/128/EEC and amendments). For individual country and specific application information please contact your

DuPont Teijin Films representative. All gauges of Mylar® 850 comply with the Food and Drug Administration regulation 21 CFR 177.1630 -- Polyethylene phthalate polymers, sections (f), (g) and (h). This regulation describes films which may be safely used in contact with all types of food excluding alcoholic beverages. Uncoated films such as Mylar® 850 can be used to contain foods during oven cooking or oven baking at temperatures above 121ºC (250 °F).


Disposal of Mylar® 850 does not present special disposal problems. Where waste occurs in a clean, uncontaminated form it can be recycled into polyester fibre. In most circumstances, once Mylar® 850 has been laminated, coated, printed or metallised, incineration with Energy Recovery is the most environmentally efficient recovery route. Mylar® 850 can also be burned in an incinerator with normal refuse or can be buried as a relatively inert material in a landfill. The disposal method should comply with appropriate local and country regulations.

Typical Properties

PropertyTest MethodUnitValue

Film Thickness    micron  15 20
Area Yield    m²/kg 48
Unit Weight    g/m² 21
Oxygen permeability  Oxtran 23°C/60/70% hum.rel.  cm3/m²/day/atm  112 84
Water vapour tramsmission rate  Lyssy 38°C/90% hum. rel.  g/m²/day  26 19
 Thermal     MD    TD
Coefficient of thermal expansion (between 20 and 50°C)    ppm/K  35   28
 Shrinkage (5 minutes at 190°C)  ASTM D1204-78 190°C for 5 minutes  %  3   3
Upper melt temperature (non heat sealable layer)  ASTM E794-85  °C    255-60
Heat seal strength:      
Seal to Seal  140°C, 40 psi, 1 sec  g/25 mm    800
Seal to plain  140°C, 40 psi, 1 sec g/25 mm
Heat seal to APET/CPET tray  180°C, 80 psi, 2 sec  g/25 mm    1000
Sealing temperature range    °C    140-220
Mechanical      MD   TD
Tensile strength at break  ASTM D882-83  MPa  165   230
Elongation at break  as above  %  120   80
Slip (coefficient of static friction)  ASTM D1894-88  Seal/Plain
   0.4 - 0.6
Haze  ASTM D1003  %  3.1 3.3
Total Luminous Transmission as above  %  88 88


Standard Put-ups

Film Standard Reel Length (metres) Multiples of Standard Reel Length Available
Mylar® 850.15 μm 2500 2, 4, 6, 8,
Mylar® 850.20 μm 2000 2, 4, 6, 8,
Mylar® 850.30 μm 1250 2, 4, 6, 8,
  Maximum available slit width: 2200mm
Standard core size: 152mm. Other core sizes available on request