BoPET

Biaxially oriented polyester film ( " boPET ") is a film of polyethylene terephthalate, which receives special properties by a stretching process.

BOPET distinguished above all by its high tensile strength, chemical, mechanical and thermal stability and transparency. BOPET is a good electrical insulator, has low water absorption (0.3%) and an extremely high dielectric strength of up to 180 V / micron. Because of the high tensile strength films can be produced very little from boPET. Typically 10 to 11 g / m², but 2.2 g / m are possible. Films of this material are not UV resistant.

The film is sold under various brand names, including HOSTAPHAN, Mylar and Melinex. The last two names are of English origin.

History and manufacturing process

A biaxially oriented polyester films were developed in the mid -1950s by DuPont, Hoechst, ICI and Rhône -Poulenc. (DuPont, Hoechst and Rhône -Poulenc had received all licenses of ICI for the then new plastic PET. ) The first production plant in Germany was at Hoechst in Wiesbaden 1955. The 1961 launched by NASA " Echo" satellite was a balloon from a 0.127 mm (5 mil) thick, metal-coated PET film with a diameter of about 30 m.

Manufactured boPET by a thin layer is applied onto a roller of molten PET is first stretched in the rolling direction and then perpendicular to the rolling direction. Then it is fixed at a high temperature so that it can no longer shrink back to its original dimensions.

BOPET can be coated by sputtering with aluminum. The product thus has a much lower gas permeability (important for food packaging film and helium balloons ), and so up to 99 % of the reflected light including a large part of the infrared spectrum. BOPET film is very resistant to tearing compared to aluminum foil. Due to its reflective properties, it can be used for thermal insulation, a thin gold - silver foil in emergency pharmacies as emergency blanket to keep warm injured or multiwall, in space.

Use

  • Aroma density food packaging
  • Electrical insulating material, eg as layers and winding insulation for LCD inverters, transformers and electrical machines
  • Aluminized as a thermal insulation material (eg in emergency blankets or tents )
  • Cover food containers (among microwave and ovenproof )
  • As reflective ornament on books, cards or art prints
  • Document covers ( for example, for archiving purposes )
  • As Überlegfolie for nondestructive use and labeling of maps
  • Dielectric in foil capacitors and as a base material for flexible printed circuit boards
  • Awning (for example Cosmos 1)
  • Balloons; in particular coated metal has a much lower helium permeability rubber
  • Basic substrate for magnetic tapes (eg VHS or audio tapes ) and Floppy Disks
  • As a membrane for electrostatic / ortho dynamic speakers and headphones, condenser or electret
  • In NASA's space suits 5 metallized Mylarschichten incorporated to make the insulation and the gas seal
  • Production of eardrums (Drum Heads )
  • Reflectors for fluorescent tubes
  • Protection for the playing of pinball machines
  • Production of low-distortion, rigid sails for sailboats
  • Use in spacers for insulating glass
  • Material for paper tape
  • In eclipse glasses
Imperial Chemical Industries Orthogonality Space blanket Solar sail Balloon (aircraft)
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