Process for the preparation of a molten mixture of aromatic hydroxyl compound and a carbonic acid diesters

摘要

A process for the production of a polycarbonate, capable of measuring the amounts of an aromatic dihydroxy compound and a carbonic acid diester or the ratio of the carbonic acid diester to the aromatic dihydroxy compound quickly and efficiently and adjusting it to obtain a polycarbonate having high quality with little variations. The ratio of the carbonic acid dieter to the aromatic dihydroxy compound in the molten mixture (A) containing the aromatic dihydroxy compound and the carbonic acid diester is measured by near infrared spectroscopy at a wavelength of 1,600 to 1,900 nm.