Fluororesin In Different Industries--communication device
Traditional communication cables are generally made of polyethylene (PE) insulation and polyvinyl chloride (PVC) jackets, but the high-density polyethylene and low-smoke polyvinyl chloride have a limiting oxygen index of only 18 and 36, at high temperatures or in open flames. It is easy to burn and has a large area of carbonization and a large amount of smoke during the combustion process. Therefore, a polymer having excellent thermal stability, low ignitability, low smog and low heat of combustion is required for wire insulation and cable sheathing. Unlike traditional PE and PVC, fluororesin has excellent electrical properties, low dielectric constant, high thermal stability, low flammability, low moisture absorption, excellent weather resistance and heat resistance, good mechanical properties, and fluorine. The surface of the resin has excellent non-stickiness and stain resistance, so the fluororesin can be safely used for wire and cable. Among the fluororesins, the performance of perfluororesin, FEP, PFA and PTFE is the most superior. The specific properties are shown in the table.
Limiting oxygen index /％
Dielectric loss factor 1MHz，23℃
（ASTM D150）9.4GHz，23 ℃
Dielectric constant，Normal temperature
FEP is a hot melt resin with a melting point of 260 ° C and is easily melt processed into very thin wires. As can be seen from the above table, the dielectric loss of FEP is small and does not change much with frequency; the limiting oxygen index (LOI) is >95%, and exhibits low smoke, low flame spread, and fire resistance without time. It is changed by extension; it has good heat resistance and can be used not only for a long time in the environment of -85 to 250 °C, but also for a short time at -200 to 260 °C; the relative dielectric constant is 2.1 at normal temperature, and it is - There is almost no change in the range of 100 to 150 ° C and 50 Hz to 100 GHz; the volume resistivity is usually >1015 Ω•m, and it varies little with temperature and humidity; and has good chemical resistance. Therefore, FEP is a high-quality cable insulation material. FEP is used as insulation material to ensure accurate data transmission at 155 Mb/s. It also meets the requirements of high-rise building ventilating systems. The requirements for flame retardant properties of smoke are not met by conventional PE insulation materials.
Perfluororesin can also be used for wiring cables in high temperature environments. FEP can be used up to 200 °C. If the maximum temperature is 250 °C, PTFE or PFA is recommended. THV is a copolymer of tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride. It is another excellent wire and cable insulation material. The polymer can exhibit different characteristics by adjusting the ratio of the three components. In addition to good insulation, flame retardancy, chemical resistance and excellent physical properties, THV resin has the most outstanding advantages of good flexibility and unique processing and mixing characteristics. THVs are low temperature processing and form strong chemical bonds with many materials and are therefore ideal candidates for multilayer structures. The electrical properties of THV determine that it is not suitable for Category 5 cables, but THV is a good insulating material for short-range communications or where flexibility, non-combustibility and chemical resistance are required. The dielectric constants of ETFE and PVDF are 2.6 and 7, respectively, which are much higher than the dielectric constant of PTFE (2.1). However, in addition to the general characteristics of fluororesin, ETFE and PVDF have better mechanical properties and scratch resistance. They are excellent in radiation resistance and retain these characteristics over a wide temperature range, so ETFE and PVDF are still widely used for low frequency cable insulation, including power, communication, aerospace and other systems.