Protective film is a crucial material in industries such as electronic manufacturing, display panels, and new energy. There are significant differences in performance, application scenarios, and durability among different types of protective films. PI (polyimide) protective film and PET (polyester) protective film are currently the two most common polymer materials on the market, each with unique advantages and limitations.

In different industrial applications, the selection of materials depends on key properties such as high temperature resistance, electrical insulation, mechanical strength, chemical resistance, and transparency. The following is the main performance comparison between PI protective film and PET protective film:

(1) High temperature resistance：

PI protective film: has a wide temperature resistance range, can withstand 200-300 ℃ for a long time, and can withstand over 400 ℃ for a short time, suitable for high-temperature processes.

PET protective film: has low temperature resistance, usually between 100~150 ℃ , and is prone to shrinkage and deformation at high temperatures, making it unsuitable for high-temperature applications.

(2) Electrical insulation

PI protective film: stable dielectric constant (about 3.0~3.5), strong voltage resistance (breakdown voltage>100kV/mm), suitable for high demand electronic protection. PET protective film: has relatively low insulation and average voltage resistance (breakdown voltage<50kV/mm).

(3) Mechanical strength and wear resistance

PI protective film: high tensile strength, good wear resistance, can be used for a long time without deformation.

PET protective film: Although it has a certain strength, its durability is low, and it is easy to become brittle or break after long-term use.

(4) Chemical resistance

PI protective film: can resist corrosion from acids, alkalis, organic solvents, etc., suitable for processes such as semiconductor and PCB manufacturing.

PET protective film: has average chemical resistance, is susceptible to solvent corrosion, and is not suitable for strong acid and alkali environments.

Weather resistance is an important indicator for measuring the long-term performance of protective films, especially in outdoor, aviation, photovoltaic and other long-term exposure environments.

(5) UV resistant：

PI film: Excellent UV resistance, can withstand long-term exposure to sunlight without discoloration or degradation.

PET film: It is greatly affected by ultraviolet radiation and will turn yellow and brittle after prolonged exposure.

(6) Moisture resistant

 PI film: not easily hygroscopic, suitable for high humidity environments such as new energy batteries and marine electronic devices.

PET film: It has a high moisture absorption rate and is prone to expansion and deformation in humid environments.

(7) Service life

PI film: can be used for more than 10 years in extreme environments, suitable for high demand fields such as aerospace and military industry.

PET film: has a short service life, generally 2-5 years, and is suitable for short-term protective applications.

(8) Production process

PI film: One step or two-step synthesis of polyimide is used, which is difficult to produce and costly.

PET film: using polyester melt extrusion process, the process is relatively mature and the production cost is low.

(9) Cost comparison

PI film: high material cost, suitable for high-end applications such as aerospace and flexible electronics.

PET film: Low cost, suitable for large-scale consumer electronics products such as mobile phone protective films and LCD panels.

Overall, PI protective film is occupying an increasingly important position in the high-end technology field due to its excellent performance, while PET protective film still has advantages in low-cost applications. With the rapid development of flexible electronics and new energy industries, the market share of PI film is expected to continue to expand, becoming an important material for future high-end manufacturing.