US4933243A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Recording medium
Assignee: Eneos Corp
•
Filing: 1988-08-15
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Granted: 1990-06-12
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Expires: 2008-08-15
Abstract
Abstract A rewritable or repeatedly employable recording medium having a base and a recording layer film provided on said base, characterized in that said recording layer film is formed by a thermotropic cholesteric liquid crystal polyester.
Inventors
- 👤 Hajime Hara
- 👤 Shingo Orii
- 👤 Tetsuo Satoh
- 👤 Tomohiro Toya
- 👤 Shigeki Iida
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 20:51
CPC Classifications
G; G03; G03F; G03F1/00; G03F1/68; C; C09; C09K; C09K19/00; C09K19/04; C09K19/38; C09K19/3804; C09K19/3809; G11; G11B; G11B7/00; G11B7/24; G11B7/241; G11B7/242; G11B7/244; G11B7/25; C09K2219/00; Y; Y10; Y10S; Y10S430/00; Y10S430/146
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
177 words
A rewritable or repeatably employable recording medium comprising a base and a recording layer film deposited on said base; said recording layer film being a film of a thermotropic cholesteric liquid crystal polyester; said recording layer film being reversibly transparent or opaque, said film being transparent at room temperature by heat-melting said film at the liquid crystal forming temperature followed by rapid cooling from said liquid crystal forming temperature to room temperature and being opaque at room temperature by heat-melting said film at the liquid crystal forming temperature followed by either (a) slow cooling to room temperature or (b) the application of an electrical or a magnetic field followed by rapid cooling to room temperature; said cholesteric liquid crystal polyester of said recording layer film formed by copolymerizing an optically active compound with a mesogen, said mesogen have a structural unit selected from the group consisting of ##STR10## the combination of ##STR11## and the combination of ##STR12## where X and Y are each independently hydrogen, halogen or an alkyl group having no more than four carbon atoms.
Claim 2
Dependent Claim
177 words
A rewritable or repeatably employable recording medium comprising a base and a recording layer film deposited on said base; said recording layer film being a film of a thermotropic cholesteric liquid crystal polyester; said recording layer film being reversibly transparent or opaque, said film being transparent at room temperature by heat-melting said film at the liquid crystal forming temperature followed by rapid cooling from said liquid crystal forming temperature to room temperature and being opaque at room temperature by heat-melting said film at the liquid crystal forming temperature followed by either (a) slow cooling to room temperature or (b) the application of an electrical or a magnetic field followed by rapid cooling to room temperature; said cholesteric liquid crystal polyester of said recording layer film formed by copolymerizing an optically active compound with a mesogen, said mesogen have a structural unit selected from the group consisting of ##STR10## the combination of ##STR11## and the combination of ##STR12## where X and Y are each independently hydrogen, halogen or an alkyl group having no more than four carbon atoms.
Claim 3
Dependent Claim
27 words
The recording medium of claim 1, wherein said thermotropic cholesteric liquid crystal polyester has a liquid crystal forming temperature in the range of 150° to 350° C.
Claim 4
Dependent Claim
22 words
The recording medium of claim 1 wherein said recording layer film has a thickness in the range of 1 to 100 μm.
Claim 5
Dependent Claim
17 words
The recording medium of claim 1, wherein (R)- or (S)-3- methyladipic acid is copolymerized with the mesogen.
Claim 6
Dependent Claim
15 words
The recording medium of claim 1, wherein (R)- or (S)-2-methyl-1,4-butanediol is copolymerized with the mesogen.
Claim 7
Dependent Claim
25 words
The recording medium of claim 4, wherein said optically active component is present in a proportion of 1 to 10 mol% of all monomer units.
References Cited (Backward Citations)
US3655971A
Cited
US3654864A
Cited
US4412059A
Cited
EP0072210A1
Cited
US4394498A
Cited
US4652626A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-06-11 | 1993-12-11 | 1994-06-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-06-11 | 1997-12-11 | 1998-06-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-06-11 | 2001-12-11 | 2002-06-12 | $7700.00 | Window Closed / Lapsed |