Patent US4880896A successfully refreshed from Google Patents.
US4880896A
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Polycarbonate for disc substrate having low bisphenol content
Assignee: Idemitsu Kosan Co Ltd
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Filing: 1988-05-09
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Granted: 1989-11-14
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Expires: 2008-05-09
Abstract
Abstract Polycarbonate for production of disc substrates, a process for efficiently producing said polycarbonate, and a disc substrate made of said polycarbonate are disclosed. This polycarbonate has a low molecular weight polymer content of not more than 3% by weight, an unreacted bisphenol content of not more than 20 ppm, and a methylene chloride content of not more than 20 ppm, and can be obtained by extracting impurity-containing powdery polycarbonate with an organic solvent such as acetone and methyl ethyl ketone. This polycarbonate is particularly suitable for production of high quality disc substrates.
Inventors
- 👤 Kazunari Otsubo
- 👤 Motonobu Ezoe
- 👤 Hideo Ago
- 👤 Koji Yamamoto
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 13:46
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; C08G64/40
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
44 words
Polycarbonate for use in production of a disc substrate, having a low molecular weight polymer content of not more than 3% by weight, an unreacted bisphenol content of not more than 20 ppm, and a methylene chloride content of not more than 20 ppm.
Claim 2
Dependent Claim
44 words
Polycarbonate for use in production of a disc substrate, having a low molecular weight polymer content of not more than 3% by weight, an unreacted bisphenol content of not more than 20 ppm, and a methylene chloride content of not more than 20 ppm.
Claim 3
Dependent Claim
43 words
The polycarbonate as claimed in claim 1 which has a low molecular weight polymer content of not more than 2% by weight, an unreacted bisphenol content of not more than 10 ppm, and a methylene chloride content of not more than 15 ppm.
Claim 4
Dependent Claim
41 words
A disc substrate made of polycarbonate having a low molecular weight polymer content of not more than 3% by weight, an unreacted bisphenol content of not more than 20 ppm, and a methylene chloride content of not more than 20 ppm.
Claim 5
Dependent Claim
41 words
A disc substrate made of polycarbonate having a low molecular weight polymer content of not more than 3% by weight, an unreacted bisphenol content of not more than 20 ppm, and a methylene chloride content of not more than 20 ppm.
Claim 6
Dependent Claim
46 words
The disc substrate as claimed in claim 3 wherein the polycarbonate has a low molecular weight polymer content of not more than 2% by weight, an unreacted bisphenol content of not more than 10 ppm, and a methylene chloride content of not more than 15 ppm.
Claim 7
Dependent Claim
15 words
The polycarbonate as claimed in claim 1 which is in the form of flake-like particles.
Claim 8
Dependent Claim
15 words
The polycarbonate as claimed in claim 2 which is in the form of flake-like particles.
References Cited (Backward Citations)
US4680374A
Cited
US4734488A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-11-13 | 1993-05-15 | 1993-11-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-11-13 | 1997-05-15 | 1997-11-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-11-13 | 2001-05-15 | 2001-11-14 | $7700.00 | Window Closed / Lapsed |