Polyester Film Applications
Food packaging general uses, film for flexible pouches, peel-able seals,
lids, snacks, barrier films, can laminations, and vacuum insulation panels
Industrial & Specialties: Hot stamping foil, release films, photo resist films, metallic yarns, adhesive tapes, plastic cards (including "smart" cards), labels, lamination films, brightness enhancement films (computer screens), solar/safety window films, medical test strips, and miscellaneous uses
Electrical: Motor wire and cable, transformer insulation films, capacitors, thermal printing tapes, membrane touch switches (computer and calculator keyboards), and flexible printed circuit films
Imaging: Microfilm, printing and pre-press films,color proofing, printing plates, drawing office drafting film, overhead transparencies, X-ray films, instant photos, business graphics, and wide format displays
Magnetics: Videotape, audio cassette tape, floppy disks, and advanced high-density computer storage media
Polyester film is used in many types of packaging applications ranging from food and drugs to industrial and consumer goods. As plain or metallized, formable, heat-shrinkable and/or coated for barrier, metal adhesion, laminating adhesion, extrusion coating adhesion, printing or sealing, PET film offers excellent characteristics for the packaging market - easy machinability, strength, high- and low-temperature resistance, crystal clarity, and printability.
The properties that make PET film ideal for packaging applications include:
Flexible packaging PET film is an excellent laminating substrate for flexible packaging structures, i.e. stand-up pouches, offering excellent flex and puncture resistance.
Lidding PET film maintains its strength at both freezer and oven temperatures, for leak-resistant wraps, lidding, and peelable seals in a wide range of food and nonfood applications.
Can laminations Copolyester film is laminated to metal for can applications.
Metallized packaging Metallized PET film is used for high barrier, decoration, and embossed holographic applications.
Susceptors Lightly metallized PET film is used in microwave susceptor constructions for browning and cooking food in microwave ovens.
Industrial & Specialty Applications
Polyester film's thermal, chemical, and dimensional stability coupled with its high tensile strength, durability, flex resistance, and clarity promote broad utilization in Industrial and Specialty applications.
Polyester film can be produced in a wide range of thickness (from one to several hundred microns) and visible light transmission from essentially 0% to 99+%. Polyester film's ability to be customized through both polymer and surface modification to fit the specific application adds to its versatility and value as a film of choice.
Key properties of PET:
Dimensional stability, both thermal and moisture
Chemical and solvent resistant
Strength, tear, and flexual resistance
Broad light transmission: optically clear to opaque
Surface treatable for adhesion to a variety of materials
Broad thickness availability
Few, if any, flexible films available today provide the broad array of performance properties for use in the Industrial and Specialty application market. PET film provides exceptional value in a wide variety of applications.
Polyester film itself is used as electrical insulation. It is also used as a laminate with other substrates, such as non-woven polyester matt (DMD), and organic and inorganic papers, such as aramid paper, silica paper, and mica paper. Polyester film can be used in UL registered electrical systems rated as high as Class F (155°C). Laminates can be used in systems rated as high as Class R (220°C).
In motor applications, polyester film is used for ground insulation as slot liners and wedges, as well as phase insulation. The high electrical breakdown voltage, coupled with polyester film's high resistance to degradation, makes it ideal for mechanical barriers in wire and cable applications. In transformer and high-voltage distribution equipment applications, polyester film is used to wrap the conductors. Polyester film, with lower extractables content, is effective for use in hermetic applications, such as refrigerator and air conditioner motor/compressor assemblies. PEN polyester film is used where higher temperature performance is required, either in the fabrication stage or in the end-use operating conditions.
Thin polyester films (two micron and below) are an integral component of capacitors, where polyester's high dielectric constant and its physical properties enable the component design to be optimized and miniaturized.
The physical properties of polyester film (such as dimensional stability, thermal stability at elevated temperatures, and coefficient of friction) combined with its mechanical properties (such as tensile break strength, tensile yield strength, and elongation at break) and its chemical and electrical resistance, make it the preferred material for a wide variety of electrical insulation applications.
The unique combination of optical, physical, thermal, and chemical properties of polyester film has made it the film of choice for many imaging applications. Some of the major applications include x-ray, photographic, printing, microfilm, photoresist/phototool, overhead projection transparencies, and drafting/reprographics. Currently, these applications account for about 30% of the total PET film consumption. Recent developments in electronic imaging may cause some decline in the use of PET film in some of these applications, but the impact is not expected to be very significant in the near future.
The properties that make PET film ideal are its:
Out of the total PET film usage for imaging applications, more than 30% goes into x-ray base. Typically, a blue-tinted 175 micron PET film is coated with a gelatin-based photosensitive coating and is used as medical x-ray film.
Generally, 100 micron and 175 micron PET film is coated with silver-sensitized layers for photographic applications mainly in professional photographic films and instant photographic applications.
PET film is used for printing applications such as in layout, masking, pre-press proofing, plate mounting, and photopolymer plates. PET film is also widely used as a base to print on for displays, signage, posters, labels, etc.
Originals and duplicates of micro-images of documents, records, drawings, etc., are produced on suitably coated PET film for easy storage, space saving, and retrieval.
Photoresist & Phototool
PET film is used in the plating or etching processes for production of rigid and flexible printed circuits.
Overhead Projection Transparencies
Coated PET film is used for making overhead projection transparencies in plain paper copying machines. Overhead projection transparencies can be printed by other techniques and written on, as well.
Drafting & Reprographic
PET base film is coated with matt or diazo-sensitized or silver-sensitized lacquers, and is widely used for drafting and in the duplication of engineering drawings. This drawing office film is considered to be more convenient for making subsequent changes in designs, and it can also be used for storage.
Polyester film is used in a variety of magnetic media, including video, camcorder and audio tapes, and data storage applications such as floppy disks and computer tapes. For all magnetics applications, the base film is further coated with a magnetically receptive coating layer. Polyester film has the excellent dimensional stability required to ensure that the heavy coating layer does not distort and faithfully records the images, sound, or data.
The largest volumes of PET film for the magnetics market sector are consumed at present in conventional video and audio tapes. Once again, the dimensional stability of polyester, plus the ability to have a magnetic coating layer adhere to the film, are key to these new applications, which are reaching exceptionally high information densities with corresponding reductions in size and faster data access times.
The dynamic nature of this market segment, with new applications growing as others mature, is typical of the innovation that exists in the polyester film industry.