Aromatic polycarbonate, a method for producing the same, and a plastic optical waveguide using the same

An aromatic polycarbonate obtained by reacting a carbonate precursor substance with a dihydric phenol comprising mainly 2,2-bis(4-hydroxyphenol)-1,1,1,3,3,3-hexafluoropropane (hereinafter referred to as bisphenol AF) purified by using an activated clay, the amount of activated clay being from 0.1 to 50% by weight based on bisphenol AF, wherein

• (i) the bisphenol AF has the following characteristics:
• with respect to a 20 wt % ethanol solution of the bisphenol AF that is dried for 10 hours at 70.+-.10.degree. C. under a reduced pressure of 10 mmHg, after being filtered through a filter having a pore diameter of 0.1 .mu.m, the light transmittance at 400 nm measured using a quartz cell having an optical path length of 250 mm, is 90% or more, and the content of impurities of the bisphenol AF, analyzed by liquid chromatography, is 0.02 wt % or less, and
• (ii) the said aromatic polycarbonate has the following characteristics:
• with respect to 5 wt % solution of the aromatic polycarbonate in methylene chloride, after being filtered through a filter having a pore diameter of 0.1 .mu.m, the light transmittance at 400 nm measured by using a quartz cell having an optical path length of 250 mm, is 85% or more in terms of light transmittance per cm of the polymer;
• and when 0.7 g of the aromatic polycarbonate is dissolved in 100 ml of methylene chloride, the specific viscosity of the thus obtained solution measured at 20.degree. C., is in the range of 0.160 to 0.418.