Method for preparing spirobiindane polycarbonates
AssigneeGeneral Electric Company
InventorsGary R. Faler, Jerry C. Lynch
Life of this patent
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Abstract
Homo- and copolycarbonates of spirobiindane bisphenols are prepared by first reacting phosgene with a substantially pure spirobiindane bisphenol in the presence of aqueous base in a heterogeneous medium at a pH in the range of about 9-11, and subsequently adding an interfacial polycarbonate formation catalyst and, optionally, a dihydroxyaromatic compound and a chain termination agent and continuing phosgene passage at a pH of at least about 10. By this method, there may be prepared homo- and copolycarbonates of 6,6'-dihydroxy-3,3,3',3'-tetramethyl-1,1-spiro(bis)indane having high molecular weight. Said homopolycarbonates and copolycarbonates with bisphenol A may be used for manufacture of optical disks having low birefrigence.
Claims18
A method for preparing a linear polycarbonate containing structural units derived from a spirobiindane bisphenol which comprises the steps of:
- (A) preparing a heterogeneous mixture in which the aqueous phase has a pH in the range of about 9-11, said mixture consisting essentially of an aqueous alkali metal or alkaline earth metal base solution;
- a substantially pure spirobiindane bisphenol of the formula ##STR8## wherein each R.sup.1 is independently C.sub.1-4 primary or secondary alkyl or halo and n is from 0 to 3, or a mixture thereof with at least one other dihydroxyaromatic compound;
- and a chlorinated aliphatic hydrocarbon constituting an organic phase in which said spirobiindane bisphenol or mixture is substantially insoluble;
- (B) passing phosgene into said mixture at a temperature in the range of about 10.degree.-50.degree. C. while maintaining the pH of the aqueous phase at a value up to about 11, until maximum homogeneity is attained;
- (C) adding an effective amount of an interfacial polycarbonate formation catalyst and continuing phosgene passage at a temperature in the range of about 10.degree.-50.degree. C. and a pH of the aqueous phase of at least about 10;
- and
- (D) recovering the linear polycarbonate from the reaction mixture.
Dependencies are inferred from the claim text.