Is Mylar a Good Insulator?
People often wonder if plastic films, often referred to as “mylar” films, can be used in electrical insulation, and the answer is yes! Certain types of plastics are excellent insulators, which means they can effectively prevent the flow of electrical current. This is a key requirement in the construction of many general electrical/electronic applications, printed and flexible circuit boards, motors and generators, batteries and capacitors, core wraps for wires and cables, and much more. Tekra offers the following films for these types of applications:
- Mylar® & Melinex® polyethylene terephthalate (polyester PET) films
- Teonex® polyethylene naphthalate (polyester PEN) films
- VALOX™ flame retardant polybutylene terephthalate blend (PBT/PET/PC) films
- ULTEM™ flame retardant polyetherimide (PEI) films
- LEXAN™ flame retardant polycarbonate (PC) films
Why Is Polyester Plastic Used to Insulate Electrical Wire?
The films listed above are commonly used for electrical insulation due to their unique set of characteristics, including:
- High Dielectric Strength: Dielectric strength refers to the amount of electrical voltage that an insulating material can withstand before experiencing electrical breakdown and becoming electrically conductive. Materials with high dielectric strength can withstand high levels of voltage before failing as an electrical insulator.
- Impressive Thermal Endurance: Heat is produced as a byproduct of the combination of voltage and electrical current in electrical applications. The listed films maintain longevity under consistent high-temperature exposure due to their various thermal resistance characteristics.
- Good Mechanical Properties: Polyester films like PET, PEN, and PBT tend to have exceptional tensile strength, impact strength, and tear resistance due to their rigid, semi-crystalline molecular structures. Amorphous-structured polymers like PC and PEI tend to have lesser mechanical properties than their semi-crystalline counterparts, but ULTEM™ and LEXAN™ FR films still have good mechanical properties for certain electrical insulation applications.
In addition to these characteristics, polyesters and polyimides are also known for their chemical and solvent resistance which makes them preferred for certain applications. Now, if you’re curious about which plastics are used for wire insulation, that list is just as impressive.
What Plastic Is Used for Wire Insulation?
Polyester films are often used for wire insulation due to their unique blend of dielectric, mechanical, thermal, chemical-resistant, and moisture-resistant properties. In particular, Mylar® WC films are produced specifically as electrical wire and cable insulation material in the telecommunications and power transmission fields, and they are often used as core wraps which provide insulation to the conductors within the wire while also protecting them from external elements like moisture and chemicals. Polyester films can be used as wire and cable insulation in various other end uses as well, including motors, batteries and other electronics.
Tekra is proud to partner of DuPont Teijin Films™ and Toyobo Film Solutions Limited™ to convert and distribute Mylar® and Melinex® PET films and Teonex® PEN films in varying thicknesses, visual appearances, and treated surfaces to ensure your polyester film is exactly what you need to properly insulate your electrical wires.
What Plastic is Used for Other Electrical Insulation?
Polyester films are versatile and consistently deliver when used for other various insulating purposes as well, such as Mylar® MO and MO21 for motors and generators or Mylar® EL and EL21 for general electrical/electronic applications. Standard and heat-stabilized polyester is also used as insulation in flexible and printed circuit boards (FCB/PCBs). More recently, polyester PET and PEN films have been identified as ideal electrical insulation and battery cell separators for lithium-ion batteries in electric vehicles. Melinex® flame retardant PET films like Melinex® FR240, FR241, and FR321 have all received UL’s VTM-0 flame rating.
Tekra also partners with Sabic Innovative Plastics™ to offer LEXAN™, VALOX™, and ULTEM™ brand flame retardant films for various electrical insulation end uses, including a line of eco-friendly films. Flame retardant Lexan™ polycarbonate and Valox™ PBT-blend films are often used as die-cut insulators and spacers and as insulation components within FCBs and PCBs. Ultem™ polyetherimide films are used in similar applications but for higher temperature environments.
For any questions regarding plastics being used to insulate electrical wire or for help selecting the right film for your specific application, please contact us online or call (866) 532-8840.