PET film is also called Polyester Film. It is one of the most widely used plastic films in the world. It has many types for choosing as per different application requirements. Here we will descript Different types of polyester film classification.

Polyester film

Polyester film (PET) is made of polyethylene terephthalate as raw material. It is made into thick sheets by the extrusion method. Then the film material is made by biaxial stretching.

Polyester (BOPET) film, opal film and other printing and packaging films are Widely used in glass and steel industry, building materials industry, printing industry, medicine and health. Polyester film is more expensive. The thickness is generally 0.012mm. It is commonly used as the outer layer material for steaming packaging. Its printability is better.

The features of polyester film

Polyester film is usually colorless transparent, glossy film (now can be added to additive particles to make it have color). Excellent mechanical properties. High rigidity. Hardness and toughness. Puncture resistance. Friction resistance. Gigh and low-temperature resistance. Chemical resistance. Oil resistance. Airtightness and good fragrance retention.

It is one of the commonly used permeability barrier composite film substrates. But the corona resistance is not good.

According to the raw materials and the stretching process, the polyester film classification can the following two kinds.

1, Biaxially oriented polyester film (BOPET for short).

Is the use of light material (i.e. in the raw material polyester chips with titanium dioxide. After drying, melting, extrusion, casting and longitudinal stretching of high-grade film. A wide range of uses.　

2, One-way stretch polyester film (CPET for short).

It is the use of semi-matte material (raw material polyester chips without the addition of titanium dioxide). After drying, melting, extrusion, casting and longitudinal stretching of the film. It has the lowest grade and price among polyester films. It is mainly used for pharmaceutical tablet packaging. Due to the low usage, manufacturers are less likely to produce it on a large scale. It accounts for about 5% of the polyester film field. Standard thicknesses are 150μm.

Classification according to the use　　

As the characteristics of the polyester film determine its different uses. Different uses of polyester films have different requirements for raw materials and additives as well as processing technology. Its thickness and technical specifications are also different. Only BOPET has many applications. So, the films classified according to their uses are all BOPET.It can be divided into the following categories.

1、Electrical insulating film.

Due to its good electrical, mechanical, thermal and chemical inertness, good insulation performance and high breakdown voltage resistance. Specially used in electronic and electrical insulation materials.

Standard thicknesses are: 25μm, 36μm, 40μm, 48μm, 50μm, 70μm, 75μm, 80μm, 100μm and 125μm. Including wire and cable insulation film (thickness 25-75μm) and touch switch insulation film (50-75μm).

2、Capacitance film.

It has high tensile strength, high dielectric constant, low loss factor, good thickness uniformity, good electrical properties, high electrical resistance, etc. It has been used in capacitor dielectric and insulation compartments.

The standard thickness is 3.5μm, 3.8μm, 4μm, 4.3μm, 4.8μm, 5μm, 6μm, 8μm, 9μm, 9.8μm, 10μm, 12μm.　　

3、Card guard film.

With good transparency. High stiffness. Good heat stability. Excellent winding performance with flat surface. Uniform longitudinal and transverse tensile properties. And has excellent performance such as waterproof, oil-proof and chemical-proof. Specially used for the protection of pictures, documents, papers and office supplies packaging. Make it flat and beautiful after stamping as a protective film. Can keep the original clear and not deformed.

Commonly used standard thicknesses are 10.75μm, 12μm, 15μm, 25μm, 28μm, 30μm, 36μm, 45μm, 55μm, 65μm, 70μm. 15μm. Above is mainly used as laser anti-counterfeiting base film or high-grade card protection film.

4、Universal film.

It has excellent strength and dimensional stability. Cold resistance and chemical stability. Widely used in composite packaging, photographic film, metal vapor deposition, audio and video recording and other substrates. There are the following specific types.

　　① Semi-reinforced films. The most important feature is the longitudinal tensile strength. It is not easy to break under large tensile forces. Mainly used for packaging seals of boxed items, etc. Commonly used standard thicknesses of 20μm, 28μm, 30μm, 36μm, 50μm.

　　②Stamping film. The biggest characteristic is good tensile strength and transparency, stable thermal properties. The bonding force with certain resins is low. It is mainly suitable for applications with small dimensional changes during high-temperature processing or as a transfer carrier. Standard thickness is 9μm, 12μm, 15μm, 19μm, 25μm, 36μm.

　　③Printed laminated packaging film. The main characteristics are good transparency. Good resistance to penetration. Excellent chemical resistance. Temperature resistance. Moisture-proof. Suitable for frozen food and packaging of food, pharmaceuticals, industrial products and cosmetics. Standard thickness is 12μm, 15μm, 23μm, 36μm.

　　④Aluminized film. The main characteristics are high strength, good temperature and chemical resistance. It has good processing as well as anti-aging properties. Corona treatment makes the adhesion of aluminum layer and film more solid. After being used for aluminizing, it can be widely used for tea, milk powder, candy, cookie and other packaging. It can also be used as decorative films such as string flower crafts and Christmas trees. It is also suitable for printing lamination or cardboard lamination. Conventional standard thicknesses are 6μm, 12μm, 16μm, 25μm, 36μm.

　　⑤ Magnetic recording film. It has the characteristics of good dimensional stability, uniform thickness and high tensile strength. Suitable for magnetic recording material base film and special packaging film. Including audio and videotape base (standard thickness has 9-12μm) and black film (standard thickness has 35-36μm).

Polyester Film Classification by quality　　

Different manufacturers have different polyester film classification according to the quality of polyester films. Generally, they are divided into A-grade, B-grade and C-grade products.

A-grade products account for 97-98% of the products sold by manufacturers in general. B-grade products account for only 2-3%. Not on the circulation of sales. The main reason is the high price of raw materials, the general manufacturers will be back to the furnace as raw materials again. Or it will be sold to textile mills as staple fiber for textile raw materials. Manufacturers sometimes also sell quarterly or semi-annual stocks of film as B-grade products.

This practice is a consistent practice of some manufacturers in Southeast Asian countries, with the aim of reducing inventory.