Mylar is the brand name for biaxially oriented polyester film (BOPET) from Mylar Specialty Films, the successor company to DuPont Teijin Films. Chemically it is polyethylene terephthalate, stretched lengthwise and crosswise, which gives the film its tensile strength, dimensional stability and dielectric strength. GOBA processes Mylar as an electrical insulating material: as roll goods, cut-to-size formats and stamped parts for transformers, motors and capacitors.
Mylar and HOSTAPHAN: two brands, one material, different manufacturers
Mylar and HOSTAPHANare both biaxially oriented PET films and, in practice, technically near interchangeable. The difference lies in the manufacturer, not the base material: Mylar comes from Mylar Specialty Films, HOSTAPHAN from Mitsubishi Polyester Film GmbH. Many competitor pages lump both names together with Melinex (manufacturer: DuPont Teijin Films Luxembourg) and treat them as synonyms. For procurement that distinction matters: type series, available coatings and lead times differ by manufacturer even though the base material is the same. For a drawing that specifically calls out “Mylar” or “HOSTAPHAN”, GOBA supplies that exact brand rather than an interchangeable BOPET equivalent.
What technical properties does Mylar have?
| Property | Value |
|---|---|
| Continuous operating temperature | up to 130 °C, thermal class B per IEC 60085 |
| Short-term peak temperature | up to about 150 °C |
| Dielectric strength | around 180 V/µm |
| Water absorption | around 0.3 % |
| UV resistance | none, unsuitable for outdoor use |
| Appearance from about 190 µm | increasingly hazy instead of clear |
Many sources quote the 130 °C continuous rating and the 150 °C peak value without distinguishing them. For sizing an insulation system, the continuous rating under the thermal class is what counts, not the short-term peak.
Where is Mylar used in electrical engineering?
In insulation applications, Mylar works wherever a thin, dimensionally stable, electrically insulating film is needed: as slot lining and layer insulation in electric motors, as winding film in transformers, and as the dielectric in film capacitors. Outside electrical engineering, the Mylar name also shows up for emergency blankets, balloons, and generically for card-sleeve storage bags among collectors. These uses share the base material but have nothing to do with GOBA's core business as an insulation material converter.
How does GOBA supply Mylar?
GOBA converts Mylar and comparable BOPET films in thicknesses from 12 to 350 µm, as slit rolls from 5 mm width with a width tolerance of ±0.1 mm, or as stamped molded partsto drawing. This runs on GOBA's polyester film production line, where Mylar is carried alongside HOSTAPHAN as one of several manufacturer brands.
A common question: if Mylar and HOSTAPHAN are technically near identical, why not simply take whichever brand is available? For most applications that is indeed possible, and GOBA advises openly toward the more economical option. Once a drawing, a UL listing or a customer specification names a specific brand, GOBA supplies exactly that brand, with no silent substitution.
GOBA Takeaway
Mylar is one of two market-leading BOPET brands that GOBA processes as an electrical insulating material. Most searches for Mylar mean interchangeable BOPET; some specifically mean the Mylar Specialty Films brand. GOBA supplies both and names the difference instead of blurring it.
