Patent ID: 7528213
Filing Date: 2009-05-05
Classification: C08G

Abstract:
1. A method for producing an aromatic polycarbonate, which comprises the following steps (I) to (III): (I) treating a molten aromatic polycarbonate prepolymer, obtained by reacting an aromatic dihydroxy compound with a diaryl carbonate, with an inert gas to thereby cause said molten prepolymer to absorb said inert gas, thereby obtaining an inert gas-absorbed molten prepolymer, wherein the amount of said inert gas absorbed into said molten prepolymer is from 0.0001 to 1 N liter per kg of said molten aromatic polycarbonate prepolymer, wherein the N liter means the volume in terms of liter or liters as measured under the normal temperature and pressure conditions, (II) feeding said inert gas-absorbed molten prepolymer into a guide-wetting fall polymerizer device (a), said guide-wetting fall polymerizer device (a) comprising: a casing having an inlet for said inert gas-absorbed molten prepolymer, an inert gas-absorbed molten prepolymer feeding zone positioned subsequent to and communicating with said inlet, a polymerization reaction zone positioned subsequent to and communicating with said inert gas-absorbed molten prepolymer feeding zone, and an outlet, for an aromatic polycarbonate, positioned subsequent to and communicating with said polymerization reaction zone, an evacuation device provided in association with said polymerization reaction zone of said casing, and a withdrawal device provided in association with said outlet of said casing, said polymerization reaction zone having a space which has a guide securely held therein and extending downwardly therethrough, said polymerization reaction zone being separated from said inert gas-absorbed molten prepolymer feeding zone through a distribution plate having a plurality of holes, through which said inert gas-absorbed molten prepolymer feeding zone communicates with said polymerization reaction zone, and (III) allowing said inert gas-absorbed molten aromatic polycarbonate prepolymer to fall along and in contact with the surface of said guide in said polymerization reaction zone, thereby effecting polymerization of said inert gas-absorbed molten prepolymer to produce an aromatic polycarbonate, wherein the casing in said guide-wetting fall polymerizer device (a) has, at its polymerization reaction zone, an upper portion defined by an upper peripheral side wall and a lower tapered portion defined by a lower peripheral wall which is inclined toward said outlet and continuously extends downwardly from said upper peripheral side wall, said lower tapered portion having said outlet at the bottom thereof, so that the produced aromatic polycarbonate falling off from said guide flows down on an inner surface of said lower peripheral wall of said lower tapered portion to said outlet, wherein said guide-wetting fall polymerizer device (a) has the following characteristics (1) to (5): (1) the opening area (A) (m (2) said guide-wetting fall polymerizer device (a) satisfies the following formula: (3) the angle (C) (°) between said upper peripheral side wall of said upper portion and the inner surface of said lower peripheral wall of said lower tapered portion, as measured with respect to a vertical cross section of said casing, satisfies the following formula: (4) the length (h) (cm) of said guide satisfies the following formula: (5) the total outer surface area (S wherein the aromatic polycarbonate is produced at a rate of 1 t/hr or more.