US4244836A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for manufacturing microcapsules of polyvinyl alcohol with liquid water-insoluble content
Assignee: Hoechst AG
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Filing: 1979-02-05
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Granted: 1981-01-13
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Expires: 1999-02-05
Abstract
Abstract Microcapsules having a shell consisting of water-soluble polyvinyl alcohol and containing a liquid, water-in-soluble material are obtained by dispersing a liquid, water-insoluble phase of a substance, substance mixture or substance solution in an aqueous phase of polyvinyl alcohol obtained by partial hydrolysis of polyvinyl acetate and having a degree of hydrolysis of from 72 to 99 mol % and dehydrating the dispersion to obtain the capsules in powder form.
Inventors
- 👤 Heinz Frensch
- 👤 Rudolf Heinrich
- 👤 Konrad Albrecht
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 06:21
CPC Classifications
A; A01; A01N; A01N25/00; A01N25/26; A01N25/28; B; B01; B01J; B01J13/00; B01J13/02; B01J13/06; B01J13/12; B01J13/125; Y; Y10; Y10T; Y10T24/00; Y10T24/14; Y10T24/1412; Y10T428/00; Y10T428/29; Y10T428/2982; Y10T428/2984; Y10T428/2985; Y10T428/2987
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
113 words
Process for microencapsulating a water-insoluble liquid in a water-soluble polyvinyl alcohol shell which comprises dispersing from 20 to 80% by volume of said liquid in from 80 to 20% by volume of an aqueous polyvinyl alcohol solution containing from 2 to 50% by weight of polyvinyl alcohol obtained by partial hydrolysis of polyvinyl acetate and having a degree of hydrolysis of from 72 to 99 mol % and a viscosity of from 2 to 18 cP, measured in a 4% aqueous solution at 20° C ., and spray drying the resulting dispersion at a temperature between about 40° and 150° C. to a residual moisture content of less than about 0.5% by weight.
Claim 2
Dependent Claim
113 words
Process for microencapsulating a water-insoluble liquid in a water-soluble polyvinyl alcohol shell which comprises dispersing from 20 to 80% by volume of said liquid in from 80 to 20% by volume of an aqueous polyvinyl alcohol solution containing from 2 to 50% by weight of polyvinyl alcohol obtained by partial hydrolysis of polyvinyl acetate and having a degree of hydrolysis of from 72 to 99 mol % and a viscosity of from 2 to 18 cP, measured in a 4% aqueous solution at 20° C ., and spray drying the resulting dispersion at a temperature between about 40° and 150° C. to a residual moisture content of less than about 0.5% by weight.
Claim 3
Dependent Claim
37 words
The process of claim 1, wherein the polyvinyl alcohol has a degree of hydrolysis of 83 to 88 mol % and a viscosity from 3 to 5 cP, measured in a 4% aqueous solution at 20° C.
Claim 4
Dependent Claim
26 words
The process of claim 1, wherein the aqueous polyvinyl alcohol solution additionally contains from 2 to 50% by weight of polyethylene glycol, glycerol or trimethylol propane.
Claim 5
Dependent Claim
21 words
The process of claim 1, wherein the water-insoluble liquid and/or the aqueous solution additionally contain wetting agents, dispersing agents and/or emulsifiers.
Claim 6
Dependent Claim
18 words
The process of claim 1, wherein the water-insoluble liquid contains at least one pesticide and optionally a solvent.
Claim 7
Dependent Claim
27 words
The process of claim 1, wherein the water-insoluble liquid is dispersed in the aqueous solution at a temperature in the range of from 10° to 80° C.
Claim 8
Dependent Claim
25 words
The process of claim 1, wherein the water-insoluble phase has a boiling point above that of water and the dispersion is dehydrated by spray drying.
Claim 9
Dependent Claim
29 words
The process of claim 7, wherein the dispersion is spray-dried at air inlet temperatures of from 120° to 150° C., optionally with the addition of highly disperse silicic acid.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-01-13 | 1984-07-14 | 1985-01-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-01-13 | 1988-07-14 | 1989-01-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-01-13 | 1992-07-14 | 1993-01-13 | $7700.00 | Window Closed / Lapsed |