EP0158449A1
Expired / Lapsed
EP
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Microcapsules and microencapsulation process
Assignee: Syngenta Crop Protection LLC
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Filing: 1985-03-13
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Granted: —
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Expires: 2005-03-13
Abstract
Abstract Novel microcapsules are disclosed in which a liquid material which is substantially insoluble in water is enclosed within a solid permeable shell of etherified urea-formaldehyde polymer, prepared by a process which comprises: (a) providing an organic solution comprising said material and a urea-formaldehyde prepolymer in which from about 50% to about 98% of the methylol groups of said prepolymer have been etherified with a C 4 -C 10 alcohol; (b) creating an emulsion of said organic solution in an aqueous solution comprising water and a surface-active agent, wherein said emulsion comprises discrete droplets of said organic solution dispersed in said aqueous solution; (c) causing in situ self-condensation of said urea-formaldehyde prepolymers by adding to said emulsion an acidifying agent and maintaining said emulsion at a pH of between about 0 and about 4 for a sufficient period of time to allow substantial completion of in situ condensation of said resin prepolymers to convert the liquid droplets of said organic solution to capsules consisting of solid permeable polymer shells enclosing said liquid material; and (d) heating said emulsion to a temperature between about 20°C and about 100°C to cause curing of said in situ formed polymers.
Inventors
- 👤 Herbert Benson Scher
- 👤 Marius Rodson
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-06 14:22
CPC Classifications
A; A01; A01N; A01N25/00; A01N25/26; A01N25/28; B; B01; B01J; B01J13/00; B01J13/02; B01J13/06; B01J13/14; B01J13/18
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
200 words
A process for the microuncapsulatiun of a liquid material which is substantially insoluble in water within a porous shell to effect a slow rate of release of said material through said shell which comprises: (a) providing an organic solution comprising, said material and a urea-formaldehyde prepolymer in which from about 50% to about 98% of the methylol groups of said prepolymer have been etherified with a C 4 -C 10 alcohol, (b) creating an emulsion of said organic solution in an aqueous solution comprising water and a surface-active agent, wherein said emulsion comprises discrete droplets of said organic solution dispersed in said aqueous solution, and (c) causing in situ self-condensation of said urea- formaldehyde prepolymers by adding to said emulsion an acidifying agent and maintaining said emulsion at a pH of between about 0 and about 4 for a sufficient period of time to allow substantial completion of in situ condensation of said resin prepolymers to convert the liquid droplets of said organic solution to capsules consisting of solid permeable polymer shells enclosing said liquid material, and (d) heating said emulsion to a temperature between about 20°C and about 100 C to cause curing of said in situ formed polymers.
Claim 2
Dependent Claim
200 words
A process for the microuncapsulatiun of a liquid material which is substantially insoluble in water within a porous shell to effect a slow rate of release of said material through said shell which comprises: (a) providing an organic solution comprising, said material and a urea-formaldehyde prepolymer in which from about 50% to about 98% of the methylol groups of said prepolymer have been etherified with a C 4 -C 10 alcohol, (b) creating an emulsion of said organic solution in an aqueous solution comprising water and a surface-active agent, wherein said emulsion comprises discrete droplets of said organic solution dispersed in said aqueous solution, and (c) causing in situ self-condensation of said urea- formaldehyde prepolymers by adding to said emulsion an acidifying agent and maintaining said emulsion at a pH of between about 0 and about 4 for a sufficient period of time to allow substantial completion of in situ condensation of said resin prepolymers to convert the liquid droplets of said organic solution to capsules consisting of solid permeable polymer shells enclosing said liquid material, and (d) heating said emulsion to a temperature between about 20°C and about 100 C to cause curing of said in situ formed polymers.
Claim 3
Dependent Claim
29 words
A process as claimed in claim 1 characterized in that from about 70% to about 90% of the methylol groups of the prepolymer of step (a) have been etherified.
Claim 4
Dependent Claim
36 words
A process as claimed in claim 1 or claim 2 characterized in that the alcohol with which the methylol groups of the prepolymer of step (a) have been etherified is a C 4 -C 6 alcohol.
Claim 5
Dependent Claim
30 words
A process as claimed in claim 3 characterized in that the alcohol with which the methylol groups of the prepolymer of step (a) have been etherified is n-butanol or iso-butanol.
Claim 6
Dependent Claim
47 words
A proess as claimed in any of claims 1 to 4 characterized in that prior to the formation of the organic solution of step (a), the prepolymer of step (a) is dissolved in an alcohol which is identical to that with which the prepolymer has been etherified.
Claim 7
Dependent Claim
30 words
A process as claimed in any of claims 1 to 5 characterized in that the surface-active agent of step (b) is selected from alkali salts of alkyl and alkylaryl sulfonates.
Claim 8
Dependent Claim
25 words
A process as claimed in any of claims 1 to 6 characterized in that the aqueous solution of step (b) further comprises a protective colloid.
Claim 9
Dependent Claim
36 words
A process as claimed in claim 7 characterized in that the protective colloid is a polyvinyl alcohol protective colloid and the aqueous solution comprises from about 0.1% to about 5.0% by weight of the protective colloid.
Claim 10
Dependent Claim
34 words
A process as claimed in any of claims 1 to 8 characterized in that the prepolymer of step (a) comprises from about 1% to about 70% of the organic solution on a weight basis.
Claim 11
Dependent Claim
30 words
A process as claimed in claim 9 characterized in that the prepolymer of step (a) comprises from about 5% to about 50% of the organic solution on a weight basis.
Claim 12
Dependent Claim
34 words
A process as claimed in any of claims 1 to 10 characterized in that the droplets of the dispersion formed in step (b) are from about 0.5 microns to about 4000 microns in diameter.
Claim 13
Dependent Claim
30 words
A process as claimed in claim 11 characterized in that the droplets of the dispersion formed in step (b) are from about 1 micron to about 100 microns in diameter.
Claim 14
Dependent Claim
34 words
A process as claimed in any of claims 1 to 12 characterized in that the in situ self-condensation in step (c) is carried out at a pH of between about 1.0 and about 3.0.
Claim 15
Dependent Claim
29 words
A process as claimed in claim 13 characterized in that the in situ self-condensation in step (c) is carried out at a temperature between about 40°C and about 70°C.
Claim 16
Dependent Claim
37 words
Microcapsules comprising a liquid core material which is substantially insoluble in water, enclosed within a solid permeable shell of self-condensed etherified urea- formaldehyde polymer prepared by a process as claimed in any of claims 1 to 14.
References Cited (Backward Citations)
FR2093646A5
Cited
DE2135721A1
Cited
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