Views: 0 Author: Site Editor Publish Time: 2021-12-31 Origin: Site
1. The characteristics of high temperature resistant cables
The high temperature resistant cable is used for the connection line of the electrical instrument and the automatic control system of the AC rated voltage 450/750V and below. Compared with the ordinary cable, the high temperature resistant cable has corrosion resistance, strong alkali resistance, strong oxidation resistance, waterproof, Wear resistance, acid and alkali resistance, aging resistance, non-combustibility, electrical insulation properties, high voltage resistance, moisture resistance and other properties, long service life, safe and reliable characteristics, widely used in aerospace, rolling stock, energy, steel, non-ferrous metal smelting , Oil exploration, electrical machinery and other fields. High temperature resistant cables with long-term continuous working temperature above 125 degrees, 135 degrees, 150 degrees, 180 degrees, 200 degrees, 250 degrees and 250 degrees, currently commonly used are irradiated polyene stems, silicone rubber, fluororesin, polyamide Cables such as imine, mica, and magnesium oxide.
2. High temperature cable insulation materials are as follows:
1. Polychlorotrifluoroethylene PCTFE
Polychlorotrifluoroethylene (PCTFE) has two types: polymer and oligomer. The oligomer is used as a fluorine oil: the molecular weight of the polymer is classified according to the application. According to its strength loss temperature, it can be divided into two levels. The first gear’s strength loss temperature is 240-270°C; the second gear’s strength loss temperature is 270-300°C, and the molecular weight is about 3x10 (5th power)-6x10(5). Power). PCTFE is mainly used as insulation and sheath material for high temperature installation wires in wires and cables.
2. Polyvinylidene fluoride PVDF
Polyvinylidene fluoride (PVDF) is a commonly used fusible fluoroplastic. It is a homopolymer of vinylidene fluoride. It has excellent corrosion resistance, stain resistance, weather resistance and resistance to ultraviolet radiation. Radiation crosslinking is used to improve mechanical properties. Generally, it is used as paint and chemical pipelines, chemical parts and container linings. However, the tensile strength of PVDF is twice that of PTFE, and the compressive strength is 6 times greater. It has abrasion resistance similar to that of nylon. It has excellent weather resistance, radiation resistance, and colorability, and can withstand the sixth power of 10. Gy's Y-ray irradiation has no burning, less smoke, and high carbonization rate when encountering high heat to make it non-flammable, so it is also often used to prepare low-frequency cable insulation, such as ceiling interlayer cables, flame-retardant cables, and heating cables Or optical fiber, etc.
3. Polytetrafluoroethylene PTFE
PTFE is abbreviated as F4, which is the most representative perfluoroplastic, commonly known as "Plastic King". PTFE has excellent heat resistance (can be used for a long time at 260°C), excellent chemical resistance, flame retardancy, low smoke and excellent electrical properties. It is an ideal material for many high-temperature cables.
The melting point of polytetrafluoroethylene is 327°C. At this high temperature, its melting turns up to 10 to the 10th power Pa·s, and it is sensitive to shear stress in the amorphous state and is prone to melt fracture. Therefore, the usual extrusion process cannot be used to completely cover the wires and cables, but the powder metallurgy method can only be used for molding, that is, the insulation is molded through the steps of preforming, sintering, and cooling.
4. Polyperfluoroethylene propylene FEP
Polyperfluoroethylene propylene (FEP) is a copolymer of TFE and hexafluoropropylene (HFP), referred to as F46. It is a fully fluorinated fluoroplastic with higher hardness and strength than PTFE, but its use temperature is lower than PTFE by 50°C. FEP has good weather resistance, radiation resistance, and chemical stability. . Like PTFE and PFA, FEP's insulation performance is also quite outstanding. Combined with its own flame retardancy, low smoke generation and easy processing, FEP becomes an ideal material for local area network (LAN) cable insulation. *It can withstand up to 205°C and can be used as heating cables, thermocouples and automotive high temperature cables.
5. Tetrafluoroethylene-ethylene copolymer ETFE
ETFE is the third most developed fluoroplastic product after PTFE (F4) and FEP (F46), referred to as F40. It is a fluoroplastic with excellent properties similar to polytetrafluoroethylene, good sound permeability, weather resistance, permeability, non-toxicity, solvent resistance and radiation resistance; it is a tough fluoroplastic , Has excellent scratch resistance and abrasion resistance. ETFE can also withstand a high temperature of 150°C, and the cross-linked ETFE can withstand a high temperature of 200°C. At the same time, it is also one of the hard-to-process fluoroplastics. ETFE is mainly used for wires and cables that require flame retardancy, low smoke generation, chemical resistance, and scratch resistance and abrasion resistance. It can be used to prepare wires and cables of various specifications, such as automobiles, aviation cables and heating cables.
6. Tetrafluoroethylene-perfluoroalkyl vinyl ether PFA
Tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer is a resin derived from perfluoroalkyl vinyl ether modified polytetrafluoroethylene, referred to as PFA, commonly known as soluble PTFE, also known as "perfluoroalkoxy fluoroplastic", It is also a fully fluorinated fluoroplastic, which improves the shortcomings of difficult processing of PTFE, and maintains all the excellent properties of PTFE, so that its performance and long-term use temperature are basically close to or maintain the level of PTFE. The basic characteristics of PFA are the same as PTFE, with better plasticity and high strength, but it can be processed by melt extrusion and can be melt processed at a lower temperature. Therefore, in wire and cable products that require PTFE characteristics and cannot be processed with PTFE, PFA can be used instead. In the production of wire and cable, PFA is more expensive, so it is usually used for high-current, high-temperature cables. Such as special heating cables, thermocouples and automotive high temperature cables.