A Detailed Explanation of Polyester Film as a Cable Raw Material

In the cable manufacturing industry, polyester film (PET film), as a core insulating and protective raw material, is widely used in the production and processing of various power cables and communication cables due to its excellent comprehensive performance. It is a key basic material ensuring the safe and stable operation of cables. Its quality and performance directly affect the insulation level, service life and applicable scenarios of cables. A thorough understanding of the characteristics, classification and application of polyester film is of great significance for cable production, material selection and quality control. The following details the polyester film for cables from multiple dimensions to help industry practitioners fully grasp relevant knowledge.

Polyester film for cables is mainly made of polyethylene terephthalate (PET), processed by casting, biaxial orientation and other processes. It is a polymer film material with high strength, high insulation and good temperature resistance. It is also often transliterated as "Mylar" in the industry and has now become a general material in the field of cable insulation and protection. Compared with other cable insulating materials, polyester film has the advantages of being thin, light, flexible and high-performance. With uniform thickness and smooth surface, it can achieve reliable insulation and protection without additionally increasing the volume and weight of the cable, adapting to the production needs of cables of different specifications and scenarios.

Excellent comprehensive performance is the key reason why polyester film has become a core raw material for cables. First, it has outstanding electrical insulation performance, with a dielectric strength of ≥120kV/mm, which can withstand a voltage of about 18kV/mm and a high volume resistivity. It can effectively isolate the cable conductor from the external environment, prevent potential safety hazards such as short circuits and leakage, improve the voltage resistance level of the cable, and adapt to the needs of thin wire diameter and high reliability scenarios. Second, it has stable temperature resistance. The conventional PET film can withstand a temperature range of -60℃ to +150℃, and the long-term service temperature is stable at about 130℃. It can adapt to various complex environments such as outdoors, high temperature and low temperature, and is not easy to age, damage, shrink or deform due to temperature changes, ensuring the normal operation of cables under extreme conditions.

Third, it has excellent mechanical properties, high tensile strength and outstanding toughness, and is not easy to tear. After precise slitting, it can adapt to the winding, laminating and other production processes of cables, effectively preventing the insulation layer from being damaged during cable processing, laying and use. At the same time, it has good dimensional stability and low shrinkage rate, which can accurately adapt to the structural forming needs of cables. In addition, polyester film also has the characteristics of good chemical stability, oil resistance, solvent resistance, moisture resistance and corrosion resistance, which can resist the erosion of external chemicals and moisture, extend the service life of cables. At the same time, it has high light transmittance, environmental protection and non-toxicity, which conforms to the green development trend of the modern cable industry.

Combined with the differentiated needs of cable production, polyester film for cables is mainly divided into two categories, adapting to the application of different scenarios. One is ordinary insulating polyester film, which is mainly used for the insulation layer and winding layer of medium and low voltage power cables and communication cables, playing a basic role in insulation and structural shaping. The common thickness is 15-75μm, and the electronic grade tolerance can be controlled at ±5μm, which can meet the production needs of conventional cables. It has outstanding cost performance and is one of the most widely used types in the current cable industry. The other is modified enhanced polyester film, which is processed by adding flame retardants, anti-aging agents and other auxiliary materials or adopting composite processes, such as flame-retardant polyester film and metalized PET film. Among them, flame-retardant products strictly comply with international flame retardant standards, can effectively prevent the spread of fire, and are suitable for cables in high-end commercial, public buildings and special scenarios; metalized products can achieve electromagnetic shielding function, adapting to the needs of communication cables, high-frequency data cables, etc.

In practical application, the role of polyester film runs through many links of cable production. As an insulation layer, it can be wrapped around the surface of the cable conductor to isolate the conductor from the shielding layer, prevent short circuits, and improve the insulation reliability of the cable. As a winding layer, it can wrap the cable core to keep the cable structure stable and the appearance clean, prevent the core from loosening, and facilitate subsequent sheath processing. Hot-melt polyester film can also enhance structural stability through thermal bonding and fixation. As a composite substrate, it forms "aluminum foil Mylar" and "copper foil Mylar" with aluminum foil and copper foil, providing mechanical support for the metal layer, and at the same time having auxiliary insulation function, ensuring the signal transmission quality of the cable and isolating electromagnetic interference. Its application scenarios cover power transmission, communication engineering, new energy, industrial control, rail transit and many other fields. From ordinary household cables to high-voltage power cables and special cables, polyester film is indispensable.

With the continuous development of the cable industry, especially the rapid rise of UHV, new energy vehicles, photovoltaic and other fields, the market's requirements for the performance of polyester film are constantly improving, promoting its development towards high-end and customization. According to industry forecasts, the apparent consumption of electrical polyester film in China will climb to 432,000 tons in 2026, with a high growth rate of 12.2%, among which the demand growth in new energy vehicles and UHV fields is the most significant. In the future, through process optimization and technological innovation, polyester film will further improve its insulation performance, temperature resistance and flame retardant performance, and at the same time achieve thinner, lighter and more environmentally friendly production, better adapt to the production needs of high-end cables and special cables, and provide more reliable raw material support for the high-quality development of the cable industry.