US4551389A
Expired / Lapsed
US
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Porous spherical cellulose acetate particles
Assignee: Daicel Corp
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Filing: 1985-01-23
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Granted: 1985-11-05
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Expires: 2005-01-23
Abstract
Abstract Cellulose acetate is formed into porous, spherical particles, having an acetylation degree of 49 to 60%, a particle diameter of 0.05 to 10 mm, a sphericity of 0.7 or larger, a pore volume of 0.4 cc/g or larger and a collapsing strength of 9 kg or higher.
Inventors
- 👤 Etsuo Ohtake
- 👤 Kazuhiro Yamazaki
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 07:24
CPC Classifications
C; C08; C08J; C08J3/00; C08J3/12; C08J3/14; C08J9/00; C08J9/28; C08J2201/00; C08J2201/04; C08J2201/054; C08J2301/00; C08J2301/08; C08J2301/10; C08J2301/12; Y; Y10; Y10T; Y10T428/00; Y10T428/29; Y10T428/2982; Y10T428/2991
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
52 words
Porous, spherical particles of cellulose acetate, which consist essentially of a cellulose acetate having an acetylation degree of 49 to 60%, a particle diameter of 0.05 to 10 mm, a sphericity of 0.7 or larger, a pore volume of 0.4 cc/g or larger and a collapsing strength of 9 kg or higher.
Claim 2
Dependent Claim
52 words
Porous, spherical particles of cellulose acetate, which consist essentially of a cellulose acetate having an acetylation degree of 49 to 60%, a particle diameter of 0.05 to 10 mm, a sphericity of 0.7 or larger, a pore volume of 0.4 cc/g or larger and a collapsing strength of 9 kg or higher.
Claim 3
Dependent Claim
15 words
Porous, spherical particles as claimed in claim 1, the surface of which has been saponified.
Claim 4
Dependent Claim
69 words
Porous, spherical particles as claimed in claim 2, in which the surface of the particles consists essentially of cellulose and the core of the particles consists essentially of cellulose acetate having an acetylation degree of 48 to 59%, a particle diameter of 0.05 to 10 mm, a sphericity of 0.7 or greater, a pore volume of 0.4 cc/g or greater and a collapsing strength of 10 kg or higher.
Claim 5
Dependent Claim
60 words
A process for preparing surface-saponified, porous, spherical particles of cellulose acetate, which comprises the step of soaking the porous, spherical particles as defined in claim 1 in an aqueous sodium hydroxide solution having a concentration of 0.2 to 2 wt. % for 1 to 6 minutes at a ratio of liquid to solid in the range between 3 and 10.
Claim 6
Dependent Claim
52 words
A process as claimed in claim 4 in which the product is particles having an acetylation degree of 48 to 59%, a particle diameter of 0.05 to 10 mm, a sphericity of 0.7 or greater, a pore volume of 0.4 cc/g or greater and a collapsing strength of 10 kg or higher.
Claim 7
Dependent Claim
26 words
Porous, spherical particles as claimed in claim 3, in which the acetylation degree is 50 to 58% and the particle diameter is 0.5 to 10 mm.
References Cited (Backward Citations)
US3837989A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-11-04 | 1989-05-06 | 1989-11-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-11-04 | 1993-05-06 | 1993-11-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-11-04 | 1997-05-06 | 1997-11-05 | $7700.00 | Window Closed / Lapsed |