초록 ▼

A digital video disc substrate comprising a polycarbonate is herein disclosed in which a main chain has a structure represented by the general formula (I) [ STR 1 ] and at least 25 mol % of this terminal group is represented by the formula (III) or (IV) [ STR 2 ] and a viscosity-average molecular we

A digital video disc substrate comprising a polycarbonate is herein disclosed in which a main chain has a structure represented by the general formula (I) [ STR 1 ] and at least 25 mol % of this terminal group is represented by the formula (III) or (IV) [ STR 2 ] and a viscosity-average molecular weight is in the range of 10,000 to 17,000, preferably 12,500 to 14,500.

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[ What is claimed is:] [1.] A digital video disc substrate comprising a polycarbonate in which a main chain has a structure represented by the general formula (I) [ STR 12 ] wherein R.sup.1 and R.sup.2 are each a halogen atom, an alkyl group having 1 to 6 carbon atoms or a phenyl group; Z is a singl

[ What is claimed is:] [1.] A digital video disc substrate comprising a polycarbonate in which a main chain has a structure represented by the general formula (I) [ STR 12 ] wherein R.sup.1 and R.sup.2 are each a halogen atom, an alkyl group having 1 to 6 carbon atoms or a phenyl group; Z is a single bond, an alkylene group or an alkylidene group having 1 to 20 carbon atoms, a cycloalkylene group or a cycloalkylidene group having 5 to 20 carbon atoms, --O--, --S--, --SO--, --SO.sub.2 -- or --CO--; p and q are each an integer of 0 to 4; and n is the number of repeating units,and a terminal group represented by the general formula (II) [ STR 13 ] wherein R.sup.3 is a halogen atom, an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms; and r is an integer of 0 to 5, at least 25 mol % of this terminal group is a group represented by the formula (III) [ STR 14 ] and a viscosity-average molecular weight is in the range of 10,000 to 17,000, wherein the viscosity-average molecular weight is determined by viscosity measurements in a methylene chloride solution at 20.degree. C.