Fluorinated copolymer, electric wire, and method for production of the electric wire
A fluorocopolymer having a tetrafluoroethylene-derived constituent unit as essential unit, and hexafluoropropylene-derived constituent unit and/or perfluoro(alkyl vinyl ether)-derived constituent unit, wherein, when the fluorocopolymer is molded into a film, the film has not more than 10000 fisheyes capable of enclosing a square with a side length of 44 μm and incapable of enclosing a square with a side length of 178 μm per 100 g and not more than 1000 fisheyes capable of enclosing a square with a side length of 178 μm per 100 g.
1. A fluorocopolymer comprising tetrafluoroethylene-derived constituent unit as essential unit, and hexafluoropropylene-derived constituent unit and/or perfluoro(alkyl vinyl ether)-derived constituent unit,
wherein, when the fluorocopolymer is molded into a film,
the film has not more than 10000 fisheyes capable of enclosing a square with a side length of 44 μm and incapable of enclosing a square with a side length of 178 μm per 100 g and not more than 1000 fisheyes capable of enclosing a square with a side length of 178 μm per 100 g.
2. The fluorocopolymer according to claim 1 ,
which has a melt flow rate of not lower than 25 g/10 minutes but lower than 48 g/10 minutes.
3. The fluorocopolymer according to claim 1 ,
which is a copolymer comprising 90 to 80% by mass of tetrafluoroethylene units and 10 to 20% by mass of hexafluoropropylene units,
a copolymer comprising 97 to 90% by mass of tetrafluoroethylene units and 3 to 10% by mass of perfluoro(alkyl vinyl ether) units, or
a copolymer comprising 92 to 75% by mass of tetrafluoroethylene units, 7 to 20% by mass of hexafluoropropylene units and 0.1 to 5% by mass of perfluoro(alkyl vinyl ether) units.
4. The fluorocopolymer according to claim 1 ,
wherein the number of terminal groups other than —CF 3 groups is not greater than 50 per 10 6 carbon atoms.
5. The fluorocopolymer according to claim 1 ,
wherein the number of fisheyes capable of enclosing a square with a side length of 44 μm and incapable of enclosing a square with a side length of 178 μm is not greater than 1000 per 100 g and the number of fisheyes capable of enclosing a square with a side length of 178 μm is not greater than 1000 per 100 g.
6. The fluorocopolymer according to claim 1 ,
wherein the perfluoro(alkyl vinyl ether) is perfluoro(propyl vinyl ether).
7. A method of producing an electric wire,
which comprises extrusion-molding the fluorocopolymer according to claim 1 , on a cable conductor.
8. The electric wire having a covering made of the fluorocopolymer according to claim 1 .
9. The electric wire according to claim 8 ,
whose diameter is not thicker than that of 20 AWG wire.
10. The electric wire according to claim 8 ,
whose diameter is not thicker than that of 40 AWG wire.