Polarizing lens made of aromatic polycarbonate
The present invention relates to a polarizing lens molded by inserting a polarizing sheet bent into a sphere or an asphere after having an aromatic polycarbonate sheet bonded via an adhesive layer to both surfaces of a film with polarized nature into a mold, and injecting aromatic polycarbonate, wherein heat treatment at a temperature not less than a temperature of 50° C. lower than the glass transition point and less than the glass transition point for an appropriate time has been performed after injecting aromatic polycarbonate to approximate a designed value of the lens curvature.
1. A method for producing a polarizing lens, the method comprising:
(a) bending a polarizing sheet onto a spherical or aspherical surface, wherein the polarizing sheet comprises (i) a polarizing film and (ii) two aromatic polycarbonate sheets comprising a first aromatic polycarbonate, wherein a first of the two aromatic polycarbonate sheets is bonded via an adhesive layer to a first surface of the polarizing film, and a second of the two aromatic polycarbonate sheets is bonded via an adhesive layer to a second surface of the polarizing film, wherein a viscosity-average molecular weight of the first and/or second aromatic polycarbonates is from 12,000 to 40,000;
(b) injecting a second aromatic polycarbonate onto one surface of the bent polarizing sheet; and then
(c) heat treating the bent polarizing sheet at a temperature in a range from 15° C. less than to 40° C. less than a glass transition temperature of the first aromatic polycarbonate;
to obtain a polarizing lens,
wherein:
wherein when a heat treatment temperature, in ° C., is X and a heat treatment time, in hours, is Y, and X is in a range from 115° C. to 135° C., a relationship between the heat treatment temperature and heat treatment time satisfies Formula 1,
15.6≦Log( Y )+0.122 X≦ 16.9 (1)
and an anisotropy of base curves in the horizontal direction and in the vertical direction of the polarizing lens after the heat treating is not more than 0.25, and
a retardation value of the aromatic polycarbonate sheet disposed on an opposite surface to the surface where the second aromatic polycarbonate was injected is in a range from 2000 nm to 20000 nm.
2. The method of claim 1 , wherein the relationship between X and Y satisfies Formula 2,
16.1≦Log( Y )+0.122 X≦ 16.8 (2)
and the anisotropy of the base curves in the horizontal direction and in the vertical direction of the polarizing lens after the heat treating is not more than 0.1.
3. The method of claim 1 , wherein the first and second aromatic polycarbonates are the same kind of aromatic polycarbonate.
4. The method of claim 1 , wherein a viscosity-average molecular weight of the first and/or second aromatic polycarbonates is from 20,000 to 35,000.
5. The method of claim 1 , wherein a thickness of each of the two aromatic polycarbonate sheets is from 50 μm to 1.5 mm.
6. The method of claim 1 , wherein a thickness of each of the two aromatic polycarbonate sheets is from 100 μm to 800 μm.