Optical member, process for producing same, and article provided with optical member
View Patent ↗To provide an optical member having an excellent transparency and heat resistance and further having favorable light resistance as compared with a molded product made of a conventional ethylene/tetrafluoroethylene copolymer, a process for producing the same, and an article provided with the optical member. An optical member made of a molded product containing a crosslinked product of an ethylene/tetrafluoroethylene copolymer comprising units (A) based on tetrafluoroethylene, units (B) based on ethylene and units (C) based on CH 2 ═CH—C n F 2n+1 (wherein n is an integer of from 2 to 10), wherein the molar ratio ((A)/(B)) of the above units (A) to the above units (B) is from 50/50 to 66/34, and the molar ratio ((C)/{(A)+(B)}) of the above units (C) to the sum of the above units (A) and the above units (B) is from 4.0/100 to 10/100.
1. An optical member, comprising:
a molded product comprising a crosslinked product of an ethylene/tetrafluoroethylene copolymer,
wherein the ethylene/tetrafluoroethylene copolymer includes
units (A) based on tetrafluoroethylene,
units (B) based on ethylene and
units (C) based on CH 2 ═CHC n F 2n+1
where n is an integer of from 2 to 6,
a molar ratio (A)/(B) of the units (A) to the units (B) is from 50/50 to 66/34, a molar ratio (C)/{(A)+(B)} of the units (C) to a sum of the units (A) and the units (B) is from 4.0/100 to 7.5/100, and the optical member has a light transmittance at a wavelength of 400 nm of at least 90.0% when the optical member has a thickness of 220 μm.
2. The optical member according to claim 1 , wherein the molar ratio (C)/{(A)+(B)} is from 4.5/100 to 7.5/100.
3. The optical member according to claim 1 , wherein the light transmittance at the wavelength of 400 nm is at least 92.0%.
4. The optical member according to claim 1 , wherein the optical member has a shrinkage upon heated at 280° C. for 5 minutes, which is within 5% in each of a vertical direction and a horizontal direction when the optical member has a thickness of 500 μm.
5. A process for producing the optical member as defined in claim 1 , comprising:
irradiating a molded product of a resin material including the ethylene/tetrafluoroethylene copolymer with radiation such that the crosslinked product of the ethylene/tetrafluoroethylene copolymer is produced,
wherein the radiation is an electron beam and irradiated in a dosage of from 1 to 10 Mrad.
6. The process according to claim 5 , wherein the radiation is irradiated in a dosage of from 3 to 10 Mrad.
7. The process according to claim 5 , wherein the radiation is irradiated in a dosage of 3 to 5 Mrad.
8. An article, comprising:
the optical member as defined in claim 1 .
9. The optical member according to claim 1 , wherein the molar ratio (C)/{(A)+(B)} is from 4.6/100 to 7.5/100.
10. The optical member according to claim 3 , wherein the molar ratio (A)/(B) of the units (A) to the units (B) is from 53/47 to 65/35, and the molar ratio (C)/{(A)+(B)} is from 4.6/100 to 7.5/100.
11. The optical member according to claim 1 , wherein n is 2.
12. The optical member according to claim 1 , wherein n is 4.
13. The optical member according to claim 10 , wherein n is 2.
14. The optical member according to claim 10 , wherein n is 4.
15. The optical member according to claim 10 , wherein the ethylene/tetrafluoroethylene copolymer includes only the units (A), the units (B) and the units (C).
16. A process for producing the optical member as defined in claim 3 , comprising:
irradiating a molded product of a resin material including the ethylene/tetrafluoroethylene copolymer with radiation such that the crosslinked product of the ethylene/tetrafluoroethylene copolymer is produced,
wherein the radiation is an electron beam and irradiated in a dosage of from 1 to 10 Mrad.
17. The process according to claim 16 , wherein the radiation is irradiated in a dosage of 3 to 5 Mrad.
18. A process for producing the optical member as defined in claim 10 , comprising:
irradiating a molded product of a resin material including the ethylene/tetrafluoroethylene copolymer with radiation such that the crosslinked product of the ethylene/tetrafluoroethylene copolymer is produced,
wherein the radiation is an electron beam and irradiated in a dosage of from 1 to 10 Mrad.
19. The process according to claim 18 , wherein the radiation is irradiated in a dosage of 3 to 5 Mrad.
20. The process according to claim 18 , wherein the radiation is irradiated in a dosage of 5 Mrad.