Frequently Asked Questions

What is polyester?

Polyester film, often called PET (polyethylene terephthalate) or BOPET (biaxially-oriented polyethylene terephthalate), is a high-strength polyester film made by stretching standard PET plastic in two directions during manufacturing, has exceptional physical properties for a plastic material, including high tensile and high temperature strength, thermal stability, uniformity, transparency, insulation properties thermal and electrical and chemical resistance.

Our large warehouse contains over 100 types of polyester films available in a wide variety of thicknesses and coating combinations. Polyester film provides exceptional performance in a wide range of applications and is often far superior to other materials such as PVC, acetate and polypropylene.

Polyester film has been the core business of HIFI Polyester Film since its foundation over 40 years ago and still represents the company’s main material today. HIFI has a large warehouse contains over 100 types of polyester ready for conversion into reels and sheets.

How does the production process work?

Polyester or polyethylene terephthalate (PET) is a plastic material produced by reacting terephthalic acid with ethylene glycol, two substances produced in the crude oil/naphtha cracking chain. During production, polyester “chips” are fed into a heated extruder and the molten polyethylene terephthalate (PET) is then transferred to a chill roll, which shapes it into an amorphous state. It is then oriented biaxially through a process known as modeling. The most common method is the sequential process, in which the film is first pulled in the direction of the machine with heated rollers and then pulled in a transverse direction, i.e. at 90° to the direction of travel, in a heated oven. Modeling ratios are typically between 3 and 4 in each direction.

Once the modeling process is complete, the film is “heat set” or crystallized under tension in the oven at temperatures generally above 200°C. The heat setting step prevents the film from assuming its original unstretched shape again and locks the molecular orientation in the plane of the film. The orientation of the polymer chains is responsible for the high strength and stiffness of biaxially oriented PET films. Another important consequence of molecular orientation is the fact that it causes the formation of numerous crystallized nuclei. Rapidly growing crystallites reach the edge of the neighboring crystallite and remain smaller than the wavelength of visible light. As a result, unfilled, biaxially oriented PET films are remarkably crystalline, despite their semi-crystalline structure.

What are the advantages of polyester film?

Polyester films have many advantages over other plastic products, including thermal stability and tensile strength. They also have excellent gas and humidity barrier properties, fair transparency and chemical stability.

The many benefits of polyester films can be exploited in different ways depending on the wide range of possible applications, some of which are listed below…

• Durability – hanging displays, tags and labels
• Transparency – overlamination, archival storage, safety clear section film
• Thermal stability – oven-safe packaging film, electrical insulation at elevated temperatures
• Printability – with different techniques, including offset and digital printing, flexography, rotogravure
• Whiteness – like synthetic paper especially for printing
• Rigidity and flatness – for tickets, tags and membership cards
• Sealability – ability to heat seal over a wide temperature range
• Chemical stability – medical test strips, labeling of hazardous substances

To learn more about the benefits of using polyester films in your applications, contact us by clicking the button below.