PTFE, PFA, FEP, PVDF Fluoroplastic products industry experts
Popular Science | Processing of Meltable Polytetrafluoroethylene (PFA)
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Industry dynamics
FAQ
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Author:
Teflon tube little sister
Source:
Dankai
Release time:
2005-07-01
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What is PFA?
The English name of PFA is: Polyfluoroalkoxy, and the Chinese name is: tetrafluoroethylene-perfluoroalkoxy vinyl ether copolymer (also known as perfluoroalkylate, soluble polytetrafluoroethylene). PFA resin is a relatively new melt-processable fluoroplastic. PFA, FEP and PTFE have similar chemical properties, but FEP can only be used below 200 degrees and PTFE cannot be injected.
Polytetrafluoroethylene (PTFE), commonly known as "plastic king", has excellent chemical resistance, high temperature resistance, low dielectric constant, non-flammability, weather resistance, low friction coefficient, non-stick and self-lubricating characteristics, etc. However, PTFE is difficult to flow after melting, and can only be formed by sintering, which limits the processing means and product design flexibility. PFA produced by copolymerization of a small amount of perfluoroalkyl vinyl ether (PAVE) and TFE almost completely retains the excellent physical properties of PTFE, has similar chemical resistance and long-term working temperature as PTFE, and has good melt processing performance, so that the product has the advantages of extremely low surface roughness, and expands the application potential of PTFE.
In addition to extrusion and molding processes, PFA can also be used in injection, transfer mold, rotational molding, dip coating, spraying and other processing processes, can be made into cables, tubes, sheets, films, coatings and other complex shapes of products, the use of almost covers the field of PTFE.
Forming and Processing of PFA
PFA resin products are mainly emulsion, powder, pellets and other forms, the current domestic products are mainly pellets, such as the Juhua Fluoropolymer Division has formed a 2kt/a PFA pellet production capacity. The melting point of PFA is 290~312 ℃, the melting point is 0.8-30g/10min, and the molding temperature is 350~410 ℃. regular processes such as compression molding, extrusion molding and injection molding can be used for PFA resin processing. The application scope of different batches of products is shown in the following table (Table 1.1).
PFA Molding
When the melting point of the PFA product is in the range of 0.8~3.0g/10min, the molecular weight is relatively high, the viscosity is large, and it is not easy to flow, and it is generally suitable for processing by compression molding. The molding temperature is 330~380 ℃, the pressure is 5.0~14.0MPa, the molding temperature is kept for 20~30min, and then the melt is slowly cooled to 200~240 ℃ under pressure before demoulding. The characteristics of high melt viscosity, low critical shear rate and high forming temperature of PFA should be taken into account when designing the mold.
PFA extrusion molding
The process and equipment of PFA extrusion molding can be used in common with those of FEP, but the molding temperature needs to be further improved. PFA also has a critical shear rate at which melt fracture occurs, the critical shear rate of high-speed extrusion type PFA is 50s-1, and the critical shear rate of low-speed extrusion or molding type PFA is 3s-1. The melt strength of PFA is greater than the melt elongation of FEP, and a greater draw ratio can be used when forming thin tubes and monofilaments.
PFA Injection Molding
When the melting point of PFA products is in the range of 16~30g/10min, and it is necessary to produce various complex shapes of aviation, aerospace industry, electronic and electrical industry parts, medicine, chemical testing equipment, etc., PFA can be processed by ordinary screw injection molding machine. Commonly used screw extruders with strong plasticizing ability have uniform mixing materials, less stagnant materials and fast stress transmission to the mold. However, the screws, barrels and molds in contact with PFA molten resin need to be made of corrosion-resistant stainless steel, and large-diameter injection ports, flow channels and pouring ports are used, and the flow channels should be as short as possible without any obstacles and sharp corners, it is best to be able to mix with the gate into a circular runner, mold cavity all corners and intersection points are round or streamlined, so that the molten resin is streamlined flow. Taking these measures and controlling the temperature of the melt can avoid the phenomenon of melt fracture on the surface or inside of the molded product.
Other molding methods of PFA include transfer molding, powder coating, dispersion impregnation molding, blow molding and vacuum molding, which are similar to the molding methods of FEP.
About Us
Shenzhen Dan Kai Technology Co., Ltd., specializing in FEP, PFA, PTFE and other fluorine plastic tube rod sheet membrane products and other insulation materials research and development, production, sales and service of manufacturing enterprises.
ShenZhen DanKai Technology Co.,ltd. is an intelligent manufacturing enterprise specializing in the R & D, production, sales and service of FEP, PFA, PTFE and other fluoroplastic tube, bar, sheet and film products as well as other insulating materials.
The company has international standards of senior R & D team and the introduction of foreign fluoroplastic products production line, some fluoroplastic products through ISO9001, SGS, FDA certification.
The main products are: ① Fluoroplastic pipes: Ptfe PTFE pipes, Fep pipes, Pfa pipes, Pvdf pipes; ② Heat shrinkable tubes: Ptfe heat shrinkable tubes, Fep heat shrinkable tubes, Pfa heat shrinkable tubes, Pvdf heat shrinkable tubes; ③ Plate rod film: Ptfe plate rod film, Feep plate rod film, Pfa plate rod film, etc. ⑤ PE special insulating material, Pvdf rod film, etc, spiral tube, spring tube, rotary cutting tube, welding rod, tee, straight, gasket, joint, cone rod, flared tube, sealing tube, braided tube, corrugated tube, etc. At the same time, it can be customized to produce various specifications of fluoroplastic products.
This article is originally created by Teflon's little sister. Welcome to pay attention and take you to grow knowledge together!
Key words:
Popular science, pfa, molding, ptfe, extrusion, processing, fep, product, temperature, melting
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