Method for producing an aromatic polycarbonate

A method for producing an aromatic polycarbonate, which comprises the following steps (I) and (II):

• (I) feeding, into a guide-wetting fall polymerizer device (a), a molten aromatic polycarbonate prepolymer obtained by reacting an aromatic dihydroxy compound with a diaryl carbonate,
• said guide-wetting fall polymerizer device (a) comprising:
• a casing having an inlet for said molten prepolymer, a molten prepolymer feeding zone positioned subsequent to and communicating with said inlet, a polymerization reaction zone positioned subsequent to and communicating with said 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 molten prepolymer feeding zone through a distribution plate having a plurality of holes, through which said molten prepolymer feeding zone communicates with said polymerization reaction zone, and
• (II) allowing said 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 molten prepolymer to produce an aromatic polycarbonate,
• wherein said 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, when the produced aromatic polycarbonate falling off from said guide gets in contact with an inner surface of said lower peripheral wall of said lower tapered portion, the aromatic polycarbonate flows down on the inner surface of said lower peripheral wall to said outlet,
• wherein said guide-wetting fall polymerizer device (a) has the following characteristics (1) to (5):
• (1) the opening area (A) (m2) of the horizontal cross section of said upper portion of said casing satisfies the following formula:
• 0.7≦A≦200;
• (2) said guide-wetting fall polymerizer device (a) satisfies the following formula:
• 20≦A/B≦1,000
• wherein A is as defined above for said characteristic (1) and B represents a minimum opening area (m2) of the cross section of said outlet;
• (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:
• 120≦C≦165;
• (4) the length (h) (cm) of said guide satisfies the following formula:
• 150≦h≦3,000;
• and
• (5) the total outer surface area (S1) (m2) of said guide satisfies the following formula:
• 2≦S1≦5,000, and
• wherein the aromatic polycarbonate is produced at a rate of 1 t/hr or more.