Patent US4789716A successfully refreshed from Google Patents.
US4789716A
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Method of manufacturing polymaleic anhydride powders
Assignee: Huels AG
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Filing: 1987-07-16
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Granted: 1988-12-06
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Expires: 2007-07-16
Abstract
Abstract A method of manufacturing pulverulent polymaleic anhydrides in which maleic anhydride is polymerized in an organic solvent in the presence of a dispersant. Polymerization results in high yields of polymaleic anhydride, as a colorless or faintly colored powder.
Inventors
- 👤 Bernhard-Peter Scholz
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 16:35
CPC Classifications
C; C08; C08F; C08F22/00; C08F22/04; C08F22/06
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
42 words
A method of manufacturing pulverulent polymaleic acid anhydride, comprising the steps of: (i) polymerizing a solution of maleic anhydride in an aromatic organic solvent in the presence of a radical-forming compound and a dispersing agent to produce powdered polymaleic acid anhydride; and
Claim 2
Independent Claim
42 words
A method of manufacturing pulverulent polymaleic acid anhydride, comprising the steps of: (i) polymerizing a solution of maleic anhydride in an aromatic organic solvent in the presence of a radical-forming compound and a dispersing agent to produce powdered polymaleic acid anhydride; and
Claim 3
Dependent Claim
8 words
(ii) separating out said powdered polymaleic acid anhydride.
Claim 4
Dependent Claim
8 words
(ii) separating out said powdered polymaleic acid anhydride.
Claim 5
Dependent Claim
25 words
The method of claim 1, wherein said radical-forming compound is selected from the group consisting of diisopropyl percarbonate, dicyclohexyl percarbonate, lauryl peroxide and dibenzoyl peroxide.
Claim 6
Dependent Claim
12 words
The method of claim 1, wherein said radical-forming compound is dibenzoyl peroxide.
Claim 7
Dependent Claim
25 words
The method of claim 1, wherein said solvent is selected from the group consisting of benzene and C 1-4 mono, di, tri and tetra-substituted alkylbenzenes.
Claim 8
Dependent Claim
19 words
The method of claim 1, wherein said solvent is selected from the group consisting of benzene, toluene and xylene.
Claim 9
Dependent Claim
10 words
The method of claim 1, wherein said solvent is toluene.
Claim 10
Dependent Claim
18 words
The method of claim 1, wherein said polymerizing step is conducted at a temperature of about 85°-120° C.
Claim 11
Dependent Claim
27 words
The method of claim 1, wherein said dispersing agent is present in an amount of 15 wt. % or less based on the weight of maleic anhydride.
Claim 12
Dependent Claim
26 words
The method of claim 1, wherein said dispersing agent is present in an amount of about 0.3-5 wt. % based on the weight of maleic anhydride.
Claim 13
Dependent Claim
14 words
The method of claim 1, wherein said dispersing agent is an ethylene-vinyl acetate copolymer.
Claim 14
Dependent Claim
13 words
The method of claim 1, wherein said solution is about 36-60% maleic anhydride.
Claim 15
Dependent Claim
14 words
The method of claim 1, wherein said separating step comprises filtering, decanting or centrifuging.
Claim 16
Dependent Claim
26 words
The method of claim 1, wherein said radical-forming compound is present in an amount less than 20 wt. % based on the weight of maleic anhydride.
Claim 17
Dependent Claim
19 words
The method of claim 13, wherein said radical-forming compound is present in an amount of about 5-15 wt. %.
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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) | 1991-12-06 | 1992-06-06 | 1992-12-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-12-06 | 1996-06-06 | 1996-12-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-12-06 | 2000-06-06 | 2000-12-06 | $7700.00 | Window Closed / Lapsed |