Patent US4935456A successfully refreshed from Google Patents.
US4935456A
Expired / Lapsed
US
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Process for preparing microencapsulated particles and the resultant products and uses thereof
Assignee: Individual
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Filing: 1988-10-14
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Granted: 1990-06-19
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Expires: 2008-10-14
Abstract
Abstract A method comprising forming a water-in-oil emulsion of an aqueous phase comprising discrete water-insoluble particles an an aqueous solution of a water-soluble polymerizable monomer, polymerizing said monomer, phase-inverting the water-in-oil emulsion to an oil-in-water emulsion, removing the oil phase from the phase-inverted emulsion to form an aqueous latex, adding to the latex an ethylenically unsaturated polymerizable second monomer, and polymerizing said second monomer to produce hydrophobic resin-encapsulated water-insoluble particles; and the resulting encapsulated particles.
Inventors
- 👤 Tsao-Chin C. Huang
- 👤 Mohamed S. El-Aasser
- 👤 John W. Vanderhoff
- 👤 Donna L. Visioli
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 17:23
CPC Classifications
C; C08; C08F; C08F285/00; C08F292/00
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
148 words
A method for preparing substantially uniform sized hydrophobic resin-coated water-insoluble microscopic particles having a size of no more than 3 microns which comprises: A forming a water-in-oil emulsion of an aqueous phase comprising an aqueous solution of a water-soluble polymerizable monomer, said aqueous phase containing discrete water-insoluble particles, B polymerizing said water-soluble monomer to encapsulate said particles in said aqueous phase in a hydrophilic polymeric shell coating, C phase-inverting the water-in-oil emulsion from step B to an oil-in-water emulsion, D removing the heterogeneous oil phase from the resulting oil-in-water emulsion to form an aqueous latex containing said particles encapsulated in a hydrophilic polymeric shell coating, E adding to the latex from step D an ethylenically unsaturated second monomer polymerizable to a water-insoluble polymer, and F polymerizing said second monomer in the latex from step E to encapsulate the hydrophilic shell-coated water-insoluble particles with a hydrophobic polymeric shell coating.
Claim 2
Independent Claim
148 words
A method for preparing substantially uniform sized hydrophobic resin-coated water-insoluble microscopic particles having a size of no more than 3 microns which comprises: A forming a water-in-oil emulsion of an aqueous phase comprising an aqueous solution of a water-soluble polymerizable monomer, said aqueous phase containing discrete water-insoluble particles, B polymerizing said water-soluble monomer to encapsulate said particles in said aqueous phase in a hydrophilic polymeric shell coating, C phase-inverting the water-in-oil emulsion from step B to an oil-in-water emulsion, D removing the heterogeneous oil phase from the resulting oil-in-water emulsion to form an aqueous latex containing said particles encapsulated in a hydrophilic polymeric shell coating, E adding to the latex from step D an ethylenically unsaturated second monomer polymerizable to a water-insoluble polymer, and F polymerizing said second monomer in the latex from step E to encapsulate the hydrophilic shell-coated water-insoluble particles with a hydrophobic polymeric shell coating.
Claim 3
Dependent Claim
25 words
A method as defined in claim 1 wherein the aqueous phase in step A includes a water-soluble or water-dispersible cross-linking agent for the said monomer.
Claim 4
Dependent Claim
25 words
A method as defined in claim 1 wherein a water-soluble low HLB emulsifier is used in step A during the formation of the water-in-oil emulsion.
Claim 5
Dependent Claim
15 words
A method as defined in claim 1 wherein the water-insoluble particles are inorganic magnetic particles.
Claim 6
Dependent Claim
19 words
A method as defined in claim 4 wherein the particles are included in Step A as an aqueous sol.
Claim 7
Dependent Claim
23 words
A method as defined in claim 5 wherein the average particle size of the sol particles ranges from about 0.1 to 1 micron.
Claim 8
Dependent Claim
19 words
A method as defined in claim 5 wherein the average sol particle size is about 0.65 microns or less.
Claim 9
Dependent Claim
26 words
A method as defined in claim 1 wherein the monomer concentration in the aqueous phase in Step A ranges from about 1% to 30% by weight.
Claim 10
Dependent Claim
31 words
A method as defined in claim 8 wherein the ratio of the aqueous phase to the oil phase in Step A ranges from about 1:5 to 2:1 on a volume basis.
Claim 11
Dependent Claim
40 words
A method as defined in claim 9 wherein from about 1 to 20% by weight based on the weight of the oil phase of a low HLB surfactant is used in the preparation of the water-in-oil emulsion in step A.
Claim 12
Dependent Claim
22 words
A method as defined in claim 10 wherein a free radical initiator is present during the water-soluble monomer polymerization in step B.
Claim 13
Dependent Claim
23 words
A method as defined in claim 11 wherein a water-soluble crosslinking agent is present in the aqueous phase during polymerization in step B.
Claim 14
Dependent Claim
40 words
A method as defined in claim 12 wherein in step B the amount of initiator ranges from about 0.01 to 1 mole % based on monomer present and the crosslinking agent from 0.5 to 20 weight % based on monomer.
Claim 15
Dependent Claim
16 words
A method as defined in claim 13 wherein the discrete water-insoluble particle is a magnetic particle.
Claim 16
Dependent Claim
13 words
A method as defined in claim 14 wherein the magnetic particle is magnetite.
Claim 17
Dependent Claim
18 words
A method as defined in claim 14 wherein the water-soluble monomer in step A is methacrylamide or acrylamide.
References Cited (Backward Citations)
US3884871A
Cited
US4446261A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-06-18 | 1993-12-18 | 1994-06-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-06-18 | 1997-12-18 | 1998-06-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-06-18 | 2001-12-18 | 2002-06-19 | $7700.00 | Window Closed / Lapsed |