FEP Copolymer Melt Extrusion for Electrical Wire Coating
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Solution Overview
Problem
Current methods for producing tetrafluoroethylene/hexafluoropropylene copolymers (FEP) face challenges in achieving high moldability and reducing defects during high-speed extrusion coating of electrical wires, leading to issues with lump formation, capacitance fluctuation, and transmission loss.
Innovation Solution
A tetrafluoroethylene/hexafluoropropylene copolymer (FEP) is developed, comprising TFE, HFP, and PFVE units, with a specific weight ratio and melt flow rate, which is processed without mixing with resins of significantly different melting points, to enhance moldability and reduce defects in extrusion coating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If PTFE is added to FEP to improve melt fracture phenomena and critical extrusion speed, then moldability is improved, but lump formation occurs between coating resin and conductive wire
Solution Approach 1:
The invention changes the chemical composition parameters of the fluororesin by incorporating PAVE units (perfluoroalkylvinylether) into the copolymer structure. This chemical modification alters the polymer's melting behavior and flow characteristics, enabling melt processing while preventing lump formation during extrusion coating, thus resolving the contradiction between improving moldability and avoiding harmful lump formation.
Solution Approach 2:
The invention creates a composite fluororesin system by combining TFE-HFP copolymer with PAVE-containing units to form a terpolymer structure. This composite material approach integrates the beneficial properties of different monomer units: TFE provides base polymer structure, HFP improves processability, and PAVE units enable melt processing while maintaining electrical properties, thereby achieving both improved moldability and elimination of lump formation.
2Productivity
If high-speed extrusion coating is performed to improve productivity, then manufacturing efficiency increases, but defects such as lump formation and capacitance fluctuation occur
Solution Approach 1:
The invention modifies the polymer's thermal and rheological parameters by incorporating PAVE units, which have lower melting points and different flow characteristics compared to conventional FEP. This enables the resin to be processed at lower temperatures with better flow control, allowing high-speed extrusion coating to be performed without generating defects such as lumps and capacitance fluctuations, thus simultaneously improving productivity and manufacturing precision.
3Reliability
If FEP with high molecular weight is used to maintain electrical properties, then insulation performance is improved, but moldability and melt processing become difficult
Solution Approach 1:
The invention creates a composite polymer structure where high molecular weight TFE-HFP copolymer provides excellent insulation performance, while incorporated PAVE units act as internal modifiers that reduce intermolecular forces and improve chain mobility. This composite structure allows the material to maintain high molecular weight benefits for electrical properties while achieving sufficient melt flow and moldability for practical manufacturing.
Solution Approach 2:
The invention changes the thermal transition parameters of the polymer by introducing PAVE units with lower melting points. This creates a broader processing temperature window where the high molecular weight polymer remains stable for maintaining electrical properties, yet becomes sufficiently mobile for melt processing, thus resolving the contradiction between insulation performance and moldability.
Data Source
AI summary
A tetrafluoroethylene/hexafluoropropylene copolymer has improved moldability in melt extrusion molding, especially with significant reduction of defects in high-speed extrusion coating of an electrical wire. The tetrafluoroethylene/hexafluoropropylene copolymer is obtained by polymerization of at least tetrafluoroethylene and hexafluoropropylene selected from the group consisting of tetrafluoroethylene, hexafluoropropylene and a third monomer without mixing with the resin which has the melting point with the difference of 20 degree C. and more from the melting point of the tetrafluoroethylene/hexafluoropropylene copolymer; and has a complex viscosity of from 2.0×I03 to 10.0×I03 Pa*s and a storage modulus of from 0.1 to 3.5 Pa*s in melt viscoelasticity measurement under the condition of atmosphere temperature of 310 degree C. and angular frequency of 0.01 radian/second. The tetrafluoroethylene/hexafluoropropylene copolymer can be used in an electrical wire as a coating on a conductive core.