Polyester Film: Types, Classification, and Applications

Polyester film, often referred to as PET film, is a versatile polymer-based material. Its applications across various industries, including fiberglass, construction, printing, and healthcare. It has gained increasing popularity among consumers due to its exceptional properties. In this article, we will delve into what polyester film is, how it is classified, and its diverse applications.

Polyester film,  known as polyethylene terephthalate (PET), is manufactured using a process that involves the extrusion of thick sheets, followed by biaxial stretching to create a thin film.

It is a crucial material in the production of items, including environmental protection films, PET sheets, milk-white films, and printing and packaging consumables. We can find its application in the fiberglass industry, construction materials, printing, healthcare, etc.

The cost of polyester film is relatively high, with a standard thickness of approximately 0.012mm. It is often used as an outer layer in packaging materials designed for cooking. It boasts excellent printing capabilities. But, the complexity of polyester film can pose challenges for customs authorities. Its identification is difficult.

Polyester film is typically transparent and colorless, with a glossy finish. Depending on the application, colored particles can be added to give it a specific hue. Its mechanical properties include high strength, rigidity, and toughness. It exhibits resistance to punctures, abrasion, and temperature extremes, both high and low. Moreover, polyester film is chemically resistant, making it impervious to oils, airtight, and capable of retaining aromas. But, it is less resistant to electrical breakdown.

Polyester film can be classified in several ways:

1. Based on Material and Production Process:

Biaxially Oriented Polyester Film (BOPET). BOPET is a high-grade film manufactured using raw materials that contain titanium dioxide, which adds gloss and brightness. It is highly transparent and has remarkable strength and rigidity. BOPET is generally used in various applications, including food packaging.  It is known for its resistance to most chemicals.

Corona-Treated Polyester Film (CPET). With the addition of titanium dioxide (semi-dull),  CPET is the lowest-tier polyester film. It is primarily used in pharmaceutical tablet packaging. Its production volume is relatively low, accounting for about 5% of the polyester film market.

2. Based on Application:

Electrical Insulation Film. Polyester film with excellent electrical, mechanical, and thermal properties serves as a material for electronic and electrical insulation. Common thicknesses range from 25μm to 125μm. It is widely used in applications such as electrical wire and cable insulation, and touch switch insulation.

Capacitor Film. Capacitor film exhibits features including high tensile strength, high dielectric constant, low loss factor, uniform thickness, excellent electrical performance, and high resistance. It is widely used in capacitors for dielectric and insulating layers, with standard thicknesses ranging from 3.5μm to 12μm.

Lamination Film. Lamination films have excellent strength, dimensional stability, cold resistance, and chemical stability. It is ideal for various applications such as composite packaging, photosensitive films, metal deposition, and audio and video recording.

Different manufacturers categorize polyester film quality in various ways. In China, they are often divided into superior, first-rate, and qualified products.  Foreign manufacturers typically use classifications like A-grade, B-grade, and C-grade. Products of A-grade quality typically account for 97-98% of the market share. B-grade products represent around 2-3%. C-grade products, which are considered substandard, are not sold in the open market.

These variations in classification exist due to the high cost of raw materials. Most manufacturers recycle them as raw materials or sell them as short fibers to textile companies. In some Southeast Asian countries, manufacturers occasionally sell their surplus polyester films as B-grade products to reduce their inventory.

In conclusion, polyester film is a remarkable material with an array of applications. Its classification, based on material, usage, and quality, provides consumers with a diverse range of options. It can help you choose the right polyester film for your specific needs.

So, we can find polyester film whether you’re in the fiberglass industry, construction sector, printing business, or healthcare field. The adaptability and utility make it an essential material in a wide range of applications.