Method for producing an aromatic polycarbonate and method of keeping raw materials thereof
AssigneeTeijin Limited
InventorsHidemi Takemoto, Toru Sawaki, Keiichi Kaneko, Katsushi Sasaki
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Abstract
An aromatic polycarbonate having excellent color is obtained by keeping an aromatic dihydroxy compound and a carbonic acid diester which are raw materials for the production of an aromatic polycarbonate in consideration of the influences of storage atmosphere, temperature, temperature difference from a storage tank and residence time.
Claims24
A method of keeping a mixture of an aromatic dihydroxy compound and a carbonic acid diester, comprising keeping a mixture consisting essentially of an aromatic dihydroxy compound and a carbonic acid diester in a molten state under the condition that the melt keeping parameter (A0) defined by the following equation (1):
- A0=−7.88+0.179×log C0+3.354×log T0+0.0078×U0+0.0017τ0 (1)
- wherein C0 is the content (ppm) of oxygen in the atmosphere of a storage tank, T0 is the temperature (° C.) of the molten mixture in the storage tank, U0 is a temperature difference (° C.) between the heating medium of the storage tank and the molten mixture, and τ0 is the average residence time (hr) of the molten mixture in the storage tank, is 0 or less.
A method of keeping a carbonic acid diester, which comprises keeping the carbonic acid diester in a molten state under the condition that the melt keeping parameter (A1) defined by the following equation (2):
- A1=−8.08+0.145×log C1+3.35×log T1+0.007×U1+0.0007τ1 (2)
- wherein C1 is the content (ppm) of oxygen in the atmosphere of a storage tank, T1 is the temperature (° C.) of the carbonic acid diester in the storage tank, U1 is a temperature difference (° C.) between the heating medium of the storage tank and the carbonic acid diester, and τ1 is the average residence time (hr) of the carbonic acid diester in the storage tank, is 0 or less.
A method of keeping an aromatic dihydroxy compound, which comprises keeping the aromatic dihydroxy compound in a powder state under the condition that the powder keeping parameter (B1) defined by the following equation (4):
- B1=−0.425+0.131×log C2+0.047×log M1−0.0012×T2+0.0017τ2 (4)
- wherein C2 is the content (ppm) of oxygen in the atmosphere of a storage tank, M1 is the water content (ppm) of the aromatic dihydroxy compound in the storage tank, T2 is the temperature (° C.) of the aromatic dihydroxy compound in the storage tank, and τ2 is the average residence time (hr) of the aromatic dihydroxy compound in the storage tank, is 0 or less.
A method of keeping a carbonic acid diester, which comprises keeping the carbonic acid diester in a powder state under the condition that the powder keeping parameter (B2) defined by the following equation (3):
- B2=−0.425+0.131×log C3+0.047×log M2−0.0012T3+0.0017×τ3 (3)
- wherein C3 is the content (ppm) of oxygen in the atmosphere of a storage tank, M2 is the water content (ppm) of the carbonic acid diester in the storage tank, T3 is the temperature (° C.) of the carbonic acid diester in the storage tank, and τ3 is the average residence time (hr) of the carbonic acid diester in the storage tank, is 0 or less.
Dependencies are inferred from the claim text.