Patent US4680374A successfully refreshed from Google Patents.
US4680374A
Expired / Lapsed
US
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Optical disc substrate made of a copolycarbonate
Assignee: Mitsubishi Chemical Corp
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Filing: 1985-08-15
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Granted: 1987-07-14
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Expires: 2005-08-15
Abstract
Abstract An optical disc substrate made of a polycarbonate containing from 5 to 100% by weight, based on the total carbonate bond-constituting units, of carbonate bond-constituting units having the formula: <IMAGE> (I) wherein each of Y and Z is a hydrogen atom or an aliphatic hydrocarbon group having from 1 to 6 carbon atoms, and each of X and W is an aliphatic hydrocarbon group having from 1 to 6 carbon atoms.
Inventors
- 👤 Masayoshi Hasuo
- 👤 Seiichi Mukai
- 👤 Hiroshi Urabe
- 👤 Seiji Yoshida
- 👤 Masahiro Nukui
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 07:29
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/24; G11B7/241; G11B7/252; G11B7/253; G11B7/2533; G11B7/2534; C; C08; C08G; C08G64/00; C08G64/04; C08G64/06; Y; Y10; Y10T; Y10T428/00; Y10T428/31504; Y10T428/31507
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
123 words
A transparent optical disc substrate having a double refraction of not greater than 5×10 -5 prepared from a polycarbonate containing at least 5 wt.%, based on the total carbonate bond-constituting units of the polycarbonate, of (I) carbonate bond-constituting units of the formula: ##STR5## wherein each of Y and Z is hydrogen, or an aliphatic hydrocarbon group having from 1 to 6 carbon atoms, and each of X and W is an aliphatic hydrocarbon group having from 1 to 6 carbon atoms, and (II) carbonate bond-constituting units of the formula: ##STR6## wherein each of Y' and Z' is hydrogen or a hydrocarbon group having from 1 to 10 carbon atoms in an amount which effectively aids in minimizing the optical distortion of the substrate.
Claim 2
Dependent Claim
123 words
A transparent optical disc substrate having a double refraction of not greater than 5×10 -5 prepared from a polycarbonate containing at least 5 wt.%, based on the total carbonate bond-constituting units of the polycarbonate, of (I) carbonate bond-constituting units of the formula: ##STR5## wherein each of Y and Z is hydrogen, or an aliphatic hydrocarbon group having from 1 to 6 carbon atoms, and each of X and W is an aliphatic hydrocarbon group having from 1 to 6 carbon atoms, and (II) carbonate bond-constituting units of the formula: ##STR6## wherein each of Y' and Z' is hydrogen or a hydrocarbon group having from 1 to 10 carbon atoms in an amount which effectively aids in minimizing the optical distortion of the substrate.
Claim 3
Dependent Claim
33 words
The optical disc substrate according to claim 1, wherein said polycarbonate contains from 5 to 60% by weight, based on the total carbonate bond-constituting units, of the carbonate bond-constituting units of formula I.
Claim 4
Dependent Claim
33 words
The optical disc substrate according to claim 1, wherein the carbonate bond-constituting units of formula I are derived from a bisphenol selected from the group consisting of 2,2-bis(4-hydroxy-3-methylphenyl)propane, 2,2-bis(4-hydroxy-3-ethylphenyl)propane, 2,2-bis(4-hydroxy-3-isopropylphenyl)propane, 2,2-bis(4-hydroxy-3-sec-butylphenyl)propane and 2,2-bis(4-hydroxy-3-tert-butylphenyl)propane.
Claim 5
Dependent Claim
19 words
The optical disc substrate according to claim 1, wherein the units of formula II are derived from bisphenol A.
Claim 6
Dependent Claim
30 words
The optical disc substrate according to claim 1, wherein the polycarbonate is produced by reacting phosgene with a bisphenol in the presence of an acid acceptor and an inert solvent.
Claim 7
Dependent Claim
46 words
The optical disc substrate according to claim 1, wherein the polycarbonate has an averge molecular weight of from 12,000 to 22,000 as calculated from the reduced viscosity (η sp ) as measured at 20° C. in a methylene chloride solution containing 6.0 g/l of the polymer.
References Cited (Backward Citations)
FR2377267A1
Cited
US4304899A
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EP0089801A1
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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 |