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Patent US4680211A successfully refreshed from Google Patents.
US4680211A
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Recording disks
Assignee: Dow Chemical Co
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Filing: 1985-07-25
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Granted: 1987-07-14
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Expires: 2005-07-25
Abstract
Abstract A recording disk for either optical or magnetic recording having improved dimensional stability as a result of reduced water absorption comprising a copolymer of a vinyl aromatic monomer and alphamethylstyrene prepared by anionic polymerization at a temperature above 61° C.
Inventors
- 👤 Thomas E. Evans
- 👤 Christine M. Bowen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 06:37
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/24; G11B7/241; G11B5/00; G11B5/84; G11B11/00; G11B11/10; G11B5/62; G11B5/73; G11B5/739; G11B5/73923; G11B5/73937; G11B7/252; G11B7/253; G11B7/2533; G11B7/2536; G11B7/26; G11B7/2534
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
55 words
A recording disk adapted for the magnetic or optical recording or retrieval of information comprising a copolymer of at least one vinyl aromatic monomer and alpha-methylstyrene prepared by anionically polymerizing the vinyl aromatic monomer and alpha-methylstyrene at a temperature greater than about 61° C. and less than the ceiling temperature of the vinyl aromatic monomer.
Claim 2
Dependent Claim
55 words
A recording disk adapted for the magnetic or optical recording or retrieval of information comprising a copolymer of at least one vinyl aromatic monomer and alpha-methylstyrene prepared by anionically polymerizing the vinyl aromatic monomer and alpha-methylstyrene at a temperature greater than about 61° C. and less than the ceiling temperature of the vinyl aromatic monomer.
Claim 3
Dependent Claim
11 words
The recording disk of claim 1 which is a optical disk.
Claim 4
Dependent Claim
59 words
The recording disks of claim 1 comprising one or more layers of a thermoplastic at least one of which layers comprises a copolymer of a vinyl aromatic monomer and alpha-methylstyrene prepared by anionically polymerizing the vinyl aromatic monomer and alpha-methylstyrene at a temperature greater than about 61° C. and less than the ceiling temperature of the vinyl aromatic monomer.
Claim 5
Dependent Claim
14 words
A recording disk according to claim 1, wherein the vinyl aromatic monomer is styrene.
Claim 6
Dependent Claim
18 words
A recording disk according to claim 1, wherein the copolymer has a molecular weight of at least 40,000.
Claim 7
Dependent Claim
20 words
A recording disk according to claim 1, wherein the copolymer comprises from about 5 percent to about 70 percent alpha-methylstyrene.
Claim 8
Dependent Claim
17 words
A recording disk according to claim 6, wherein the copolymer comprises at least about 20 percent alpha-methylstyrene.
Claim 9
Dependent Claim
28 words
A recording disk according to claim 1 having a diameter of at least about 8 inches (200 mm) and a thickness less than about 0.12 inch (3.0 mm).
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-07-13 | 1991-01-12 | 1991-07-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-07-13 | 1995-01-12 | 1995-07-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-07-13 | 1999-01-12 | 1999-07-14 | $7700.00 | Window Closed / Lapsed |