Patent US4904755A successfully refreshed from Google Patents.
US4904755A
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Low birefringent polyesters in optical devices
Assignee: Eastman Kodak Co
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Filing: 1989-01-23
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Granted: 1990-02-27
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Expires: 2009-01-23
Abstract
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.
Inventors
- 👤 Julie S. Machell
- 👤 Paul D. Yacobucci
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 10:18
CPC Classifications
G; G02; G02B; G02B1/00; G02B1/08; C; C08; C08G; C08G63/00; C08G63/02; C08G63/12; C08G63/16; C08G63/18; C08G63/19; C08G63/193
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
62 words
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.
Claim 2
Dependent Claim
62 words
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.
Claim 3
Dependent Claim
23 words
The optical device according to claim 1 wherein the absolute value of the birefringence of said polymeric material is less than about 0.005.
Claim 4
Dependent Claim
21 words
The optical device according to claim 1 wherein the glass transition temperature of said polymeric material is greater than 125° C.
Claim 5
Dependent Claim
21 words
The optical device according to claim 1 wherein the glass transition temperature of said polymeric material is greater than 150° C.
Claim 6
Dependent Claim
24 words
The optical device according to claim 1 wherein said aromatic dicarboxylic acid is selected from the group consisting of terephthalic acid and isophthalic acid.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-02-26 | 1993-08-28 | 1994-02-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-02-26 | 1997-08-28 | 1998-02-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-02-26 | 2001-08-28 | 2002-02-27 | $7700.00 | Window Closed / Lapsed |