	US 7,563,858 B2
	Method for stably producing an aromatic polycarbonate
Ichiro Kakihara, Kurashiki (Japan); and Hiroshi Hachiya, Kurashiki (Japan)
Assigned to Asahi Kasei Chemicals Corporation, Tokyo (Japan)
Appl. No. 10/593,035 PCT Filed Jun. 14, 2005, PCT No. PCT/JP2005/010860 § 371(c)(1), (2), (4) Date Sep. 15, 2006, PCT Pub. No. WO2005/121212, PCT Pub. Date Dec. 22, 2005.
Claims priority of application No. 2004-176206 (JP), filed on Jun. 14, 2004.
Prior Publication US 2008/0255324 A1, Oct. 16, 2008
Int. Cl. C08G 64/00 (2006.01); C08G 63/00 (2006.01)

U.S. Cl. 528—196 [422/129; 422/131; 502/150; 528/198; 528/480]

5 Claims

1. A method for producing an aromatic polycarbonate, which comprises continuously reacting an aromatic dihydroxy compound with a diaryl carbonate in a closed, reactor-pipeline system,

said closed, reactor-pipeline system comprising:

a plurality of reactors which are liquid-tightly connected through a pipeline toward an outlet for a final aromatic polycarbonate product, said pipeline comprising one or more pipes, wherein said plurality of reactors include at least two reactors connected in series, and

at least one filter secured in the pipe or pipes of said reactor-pipeline system,

said method further comprising:

a step of simultaneously or separately taking out the or each filter clogged with foreign matter to the outside of said reactor-pipeline system,

a step of subjecting the or each filter to washing in the outside of said reactor-pipeline system, and

a step of returning of the resultant washed filter into the inside of the pipe or pipes of said reactor-pipeline system,

wherein said washing is performed with the below-mentioned washing agents used in the following order:

an aqueous solution of a basic compound with a pH value of from 7.5 to 10,

an aromatic monohydroxy compound, and

a molten mixture of an aromatic dihydroxy compound and a diaryl carbonate, said molten mixture containing a basic compound in an amount of from 1 to 10,000 ppb.