Low birefringent polyesters in optical devices
AssigneeEastman Kodak Company
InventorsJulie S. Machell, Paul D. Yacobucci
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Abstract
There are disclosed low birefringent polyesters that are useful in optical devices. The polyesters include units having opposite optical anisotropies. By varying the ratio of the units in the copolymer, the birefringence of an article made from the copolymer can be controlled as desired. The polyester is a substantially optically anisotropic polyester having diol repeating units derived from 9,9-bis(4-hydroxyphenyl)fluorene and at least about 40% by weight of the diacid repeating units derived from aliphatic or cycloaliphatic dicarboxylic acids, the remainder of the diacid repeating units being derived from aromatic dicarboxylic acids.
Claims5
In an optical device wherein light passes through a polymeric material, the improvement wherein said polymeric material is a substantially optically anisotropic polyester having diol repeating units derived from 9,9-bis(4-hyroxyphenyl)fluorene and at least about 40% by weight of the diacid repeating units derived from aliphatic or cycloaliphatic dicarboxylic acids, the remainder of the diacid repeating units being derived from aromatic dicarboxylic acids.
Dependencies are inferred from the claim text.