Copolymer and composition containing same
To provide a copolymer capable of producing a molded article excellent in strength at a high temperature. A copolymer comprising ethylene units, tetrafluoroethylene units and other monomer units, wherein to the sum of ethylene units and tetrafluoroethylene units, the ethylene units are from 49 to 40 mol % and the tetrafluoroethylene units are from 51 to 60 mol %; to all units in the copolymer, other monomer units are from 2.6 to 6.0 mol %; the melting point is at least 230° C.; and the melt flow rate is from 1 to 15 g/10 min.
1. A copolymer comprising units derived from ethylene, units derived from tetrafluoroethylene, and units derived from a monomer other than ethylene and tetrafluoroethylene, wherein
to a sum of the units derived from ethylene and the units derived from tetrafluoroethylene, a proportion of the units derived from ethylene is from 49 to 40 mol %, and a proportion of the units derived from tetrafluoroethylene is from 51 to 60 mol %,
to all units in the copolymer, a proportion of the units derived from said monomer other than ethylene and tetrafluoroethylene is from 2.6 to 6.0 mol %,
a melting point of the copolymer is at least 230° C., and
a melt flow rate of the copolymer measured in accordance with ASTM D3159 under conditions of a temperature of 297° C. and a load of 49 N, is from 1 to 15 g/10 min.
2. The copolymer according to claim 1 , wherein the units derived from said monomer other than ethylene and tetrafluoroethylene include units derived from a compound represented by CH 2 ═CX(CF 2 ) n Y, where X and Y are each independently a hydrogen atom or a fluorine atom, and n is an integer of from 2 to 8.
3. The copolymer according to claim 2 , wherein in said compound represented by CH 2 ═CX(CF 2 ) n Y, n is from 3 to 7.
4. A composition comprising the copolymer of claim 1 , and a heat stabilizer.
5. The composition according to claim 4 , wherein the copolymer claim 1 is included in an amount of at least 80 mass %.
6. The composition according to claim 4 , wherein the copolymer claim 1 is included in an amount of at least 90 mass %.
7. The composition according to claim 4 , further comprising another copolymer comprising units derived from ethylene, units derived from tetrafluoroethylene, and units derived from a monomer other than ethylene and tetrafluoroethylene.
8. The composition according to claim 7 , wherein said another copolymer is a copolymer having units derived from a monomer having a polar functional group and having no fluorine atom.
9. The composition according to claim 7 , wherein a content of said another copolymer is at most 30 parts by mass, to 100 parts by mass of the copolymer.
10. A molded article formed by molding the copolymer of claim 1 or a composition comprising the copolymer and a heat stabilizer, wherein an elastic limit elongation at 200° C. of the molded article is at least 8.5%.
11. The molded article according to claim 10 , wherein the elastic limit elongation is at most 20%.
12. A molded article formed by molding the copolymer of claim 1 or a composition comprising the copolymer and a heat stabilizer, wherein a tensile strength at break at 200° C. of the molded article is at least 3 MPa.
13. The molded article according to claim 12 , wherein the tensile strength at break is at most 10 MPa.
14. A molded article formed by molding the copolymer of claim 1 or a composition comprising the copolymer and a heat stabilizer, wherein an elastic limit elongation at 200° C. of the molded article is at least 8.5%, and a tensile strength at break at 200° C. of the molded article is at least 3 MPa.