Patent ID: 6252034
Filing Date: 2001-06-26
Classification: C08G

Abstract:
A process for producing a polycarbonate resin through the melt polycondensation of an aromatic diol compound and a carbonic acid diester compound, wherein (1) valves, (2) pumps, (3) flanges and (4) flow passages having the following structures and characteristic properties are used in the production process:(1) valve; Y-shaped globe valve which has a heat durability of 150.degree. C. or more, substantially no leakage under a vacuum pressure of 40,000.times.10.sup.-6 MPa or less and a pressure durability of 0.1 MPa or more, and whose liquid contact portion is made from a material having corrosion resistance against a monohydroxy compound formed by a reaction between the aromatic diol compound and the carbonic acid diester compound;(2) gear pump; gear pump which has a heat durability of 150.degree. C. or more, substantially no leakage under a vacuum pressure of 40,000.times.10.sup.-6 MPa, a pressure durability of 0.1 MPa or more and a delivery pressure of 1 MPa or more, whose liquid contact portion is made from a material having corrosion resistance against a monohydroxy compound formed by a reaction between the aromatic diol compound and the carbonic acid diester compound, and which has such a structure that the reaction mixture under a vacuum pressure of 40,000.times.10.sup.-6 MPa or less can be discharged and that the reaction mixture for lubricating contact portions among a gear, shaft and other gear pump members does not return into the pump and is discharged to the outside of the pump;(3) flange; flange which has a heat durability of 150.degree. C. or more, substantially no leakage under a vacuum pressure of 40,000.times.10.sup.-6 MPa or less and a pressure durability of 0.1 MPa or more, whose liquid contact portion is made from a material having corrosion resistance against a monohydroxy compound formed by a reaction between the aromatic diol compound and the carbonic acid diester compound, and which has a heating medium jacket therein; and(4) flow passage; flow passage which has a heat durability of 150.degree. C. or more, substantially no leakage under a vacuum pressure of 40,000.times.10.sup.-6 MPa or less and a pressure durability of 0.1 MPa or more, whose liquid contact portion is made from a material having corrosion resistance against a monohydroxy compound formed by a reaction between the aromatic diol compound and the carbonic acid diester compound, which is restricted and/or expanded at a vertical angle of 20.degree. or less, and whose surface is smooth without level differences,wherein substantially no leakage means that the leakage of gas from the outside of the valve, the gear pump, the flange or the flow passage is 120.times.10.sup.-6 MPa/h or less based on 1 liter of the inner capacity when the ultimate vacuum degree is 13.3.times.10.sup.-6 MPa.