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Material

High-Performance Plastics for Demanding Applications

Fluoropolymers are long-chain polymers in which a large proportion or even all of the hydrogens contained are usually replaced by fluorine. Fluorine atoms have the highest electro negativity, which means that the carbon-fluorine compound has a very high binding energy. For this reason, fluoropolymers exhibit extremely high temperature and chemical resistance. They also have excellent electrical insulation properties, superior weathering resistance, good notched impact strength, anti-adhesive behavior and they are self-extinguishing.

 

Typical areas of application for fluoropolymers are:

  • Automotive cables (sensor cable / NOX / Lambda)
  • High temperature cables
  • High frequency cables
  • Chemical resistant cables
  • Miniature cables
  • Flat ribbon cables
  • Heating cables
  • Control cables
  • Connecting cables

Fluoropolymers are divided into thermoplastically processable (FEP, ETFE, PFA, etc.) and non-thermoplastically processable (PTFE) plastics. This results in different processing methods. While the thermoplastic fluoropolymers are melted by means of extruders and then applied to the conductor and cooled, PTFE cannot be melted due to its high molecular weight. Various pressing and sintering techniques must therefore be used to process the powdered PTFE.

Processing Methods

  • Paste Extrusion

    In paste extrusion, the PTFE is pressed onto the conductor under high pressure in a discontinuous process. Before the PTFE can be used in the paste extruder, a molded part (a so called dummy) must first be produced. For this purpose, the PTFE poweder is pre-mixed together with a lubricant and the color and compressed. these cylindral dolls are filled into the paste extruder and pressed onto the conductor.

    The conductor is then sintered at very high temperatures. in this sintering process, known from ceramics, the compacted powder particles sinter together to form a homogeneous structure.

  • PTFE Tape Production

    As with paste extrusion, the PTFE powder must first be prmixed for tape production, and a molded part produced. The difference is that the PTFE is not pressed into a cylinder but into a full round rod. this round rod is then processed into a ling thick thread called a “worm”. In the next process, the worm is calendared to the desired width an thickness to form a strip.

    The bands can be used to bond various cables an lines in a further process. Beforde the PTFE is sintered, the cables must first be “degreased” in a vacuum furnace and then sintered at hig temperatures.

  • Expand films (Hei-Tape)

    For the production of espanded films (Hei-Tape), uncolored PTFE powder is also compressed into a full round rod. This is then pressed into a thick and wide tape using a wide slot die. This tape is streched to very thin tapes on a special machine. the streching is achieved by roller systems rotating at different speeds- A distinction is made between monoaxial an biaxial streching.

    With monoaxial streching, streching degrees of up to 1000% can be reached. These “expanded” films are partially sintered and are used as release films or insulation films.

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