US4542176A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Preparation of particulate gels
Assignee: BTG International Ltd
•
Filing: 1984-11-05
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Granted: 1985-09-17
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Expires: 2004-11-05
Abstract
Abstract A process for the preparation of a particulate gel, which process comprises (i) contacting the gel with a swelling agent and (ii) subjecting the swollen gel to shear stress such that the swollen gel is comminuted to particles.
Inventors
- 👤 Neil B. Graham
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 08:49
CPC Classifications
C; C08; C08J; C08J3/00; C08J3/12; A; A61; A61K; A61K9/00; A61K9/14; A61K9/16; A61K9/1605; A61K9/1629; A61K9/1641; A61L; A61L15/00; A61L15/16; A61L15/42; A61L15/60; A61L9/00; A61L9/015; A61L9/04; A61L9/048; B; B01; B01J; B01J13/00; B01J13/0052; B01J13/0069; C08G; C08G18/00; C08G18/06; C08G18/28; C08G18/40; C08G18/48; C08G18/4833; C08G2210/00; C08J2300/00; C08J2300/14
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
61 words
A process for the preparation of a particulate hydrogel of a homo-or copolymer which can exhibit syneresis, which process comprises: (i) contacting the hydrogel with a swelling agent; (ii) subjecting the swollen hydrogel to shear stress such that the swollen hydrogel is comminuted to particles; and (iii) drying the swollen particulate hydrogel by varying its temperature so that it exhibits syneresis.
Claim 2
Dependent Claim
61 words
A process for the preparation of a particulate hydrogel of a homo-or copolymer which can exhibit syneresis, which process comprises: (i) contacting the hydrogel with a swelling agent; (ii) subjecting the swollen hydrogel to shear stress such that the swollen hydrogel is comminuted to particles; and (iii) drying the swollen particulate hydrogel by varying its temperature so that it exhibits syneresis.
Claim 3
Dependent Claim
12 words
The process according to claim 1, wherein the swelling agent comprises water.
Claim 4
Dependent Claim
14 words
The process according to claim 2 wherein the swelling agent consists essentially of water.
Claim 5
Dependent Claim
84 words
The process according to claim 2 or 3, wherein the hydrogel comprises a hydrophilic homo- or copolymer comprising residues derivable from at least one of the following monomer classes: (a) (meth)acrylic acid, (meth)acrylamide or an unsubstituted or hydroxy-substituted ethyl or propyl (meth)acrylate, or a poly(oxyethylene) ester of (meth)acrylic acid; (b) a substituted or unsubstituted cyclic mono or polyether having from 3 to 6 ring atoms; or (c) a substituted or unsubstituted vinyl alcohol, aldehyde, ether, acetal,ketone, ester or substituted or unsubstituted N-vinyl heterocyclic compound.
Claim 6
Dependent Claim
15 words
A particulate gel prepared in accordance with the process of claim 1, 2 or 3.
Claim 7
Dependent Claim
12 words
The particulate gel according to claim 5 which comprises an active substance.
Claim 8
Dependent Claim
16 words
The process according to claim 2, 3 or 1, wherein the hydrogel comprises a homo-or copoly(alkylene)oxide.
Claim 9
Dependent Claim
21 words
The process according to claim 7, wherein the poly(alkylene oxide) is cross-linked through reaction with isocyanate or unsaturated cyclic ether groups.
Claim 10
Dependent Claim
16 words
The process according to claim 2, 3, or 1, wherein the hydrogel comprises a poly(ethylene oxide).
Claim 11
Dependent Claim
31 words
The process according to claim 2, 3 or 1, wherein the temperature at which the swollen gel is subjected to shear stress is regulated to provide a desired average particle size.
Claim 12
Dependent Claim
19 words
The process according to claim 2, 3 or 1, wherein an active substance is incorporated in the swelling agent.
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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) | 1988-09-16 | 1989-03-18 | 1989-09-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-09-16 | 1993-03-18 | 1993-09-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-09-16 | 1997-03-18 | 1997-09-17 | $7700.00 | Window Closed / Lapsed |