US5270445A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of forming fine polymer particles and polymer-encapsulated particulates
Assignee: Coulter Systems Corp
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Filing: 1991-01-24
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Granted: 1993-12-14
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Expires: 2011-01-24
Abstract
Abstract A polyamide polymer and one of methanol, ethanol and 2-propanol are formed into a solution by heating at 70 degrees Celsius for approximately two hours, the resulting solution is cooled to precipitate the polymer as particles from said solution. Alternatively, a non-solvent to said polymer may be added to effect precipitation of said polymer particles. The solvent is removed and the particles isolated and dried to form a dry powder. Fine particulate material such as a pigment, may be included with the polymer and solvent in formation of the solution. The resulting solution may be cooled at a rapid rate to precipitate the particles as polymer-encapsulated pigment particles of generally uniform size and morphology, the surface characteristics such as surface area being controlled. The precipitated polymer particles may be classified when dispersed in a dispersant medium, as mono-dispersed particles. The polymer-encapsulated pigment particles are isolated, dried and may be redispersed in a dispersant medium along with a charge control agent and a steric stabilizer to form a liquid toner for electrophotographic imaging. Alternatively, the solvent can be removed by washing with a non-solvent, the charge control agent added with the dispersant to form the liquid toner. Particles other than pigment may be polymer-encapsulated using the precipitation method disclosed. The non-solvent may be any solvent which has a poor thermodynamic quality for the polymer.
Inventors
- 👤 Wei-Hsin Hou
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 00:32
CPC Classifications
C; C08; C08J; C08J3/00; C08J3/20; C08J3/205; C08J3/21; C08J3/12; C08J3/14; G; G03; G03G; G03G9/00; G03G9/08; G03G9/0825; G03G9/093; G03G9/09392; G03G9/12
Claims Analysis
Total Claims: 36
Claim 1
Independent Claim
62 words
A method of forming fine polymer particles of generally uniform size and morphology comprising the steps of: forming a solution of the polymer and a good solvent for said polymer; adding a non-solvent for the polymer to said solution to precipitate said polymer as fine particles of generally uniform size and morphology; isolating the precipitated fine polymer particles; and, removing the solvent.
Claim 2
Independent Claim
62 words
A method of forming fine polymer particles of generally uniform size and morphology comprising the steps of: forming a solution of the polymer and a good solvent for said polymer; adding a non-solvent for the polymer to said solution to precipitate said polymer as fine particles of generally uniform size and morphology; isolating the precipitated fine polymer particles; and, removing the solvent.
Claim 3
Independent Claim
56 words
A method of forming fine polymer particles of generally uniform size and morphology comprising the steps of: forming a solution of the polymer and a good solvent for said polymer; cooling the solution to precipitate the polymer as fine polymer particles of generally uniform size and morphology; isolating the fine polymer particles; and, removing the solvent.
Claim 4
Independent Claim
56 words
A method of forming fine polymer particles of generally uniform size and morphology comprising the steps of: forming a solution of the polymer and a good solvent for said polymer; cooling the solution to precipitate the polymer as fine polymer particles of generally uniform size and morphology; isolating the fine polymer particles; and, removing the solvent.
Claim 5
Dependent Claim
20 words
The method as claimed in claim 2 in which a non-solvent is introduced to the solution before the cooling thereof.
Claim 6
Independent Claim
27 words
The method as claimed in claims 1 or 2 in which said polymer and solvent are mixed and heated for a predetermined duration to form said solution.
Claim 7
Independent Claim
32 words
The method as claimed in claims 1 or 2 in which said polymer and solvent are mixed and heated to approximately 70 degrees Celsius for a predetermined duration to form said solution.
Claim 8
Independent Claim
25 words
The method as claimed in claims 1 or 2 in which said solution is cooled rapidly immediately prior to precipitation of the fine polymer particles.
Claim 9
Independent Claim
19 words
The method as claimed in claims 1 or 2 in which the precipitated particles are dried subsequent to isolation.
Claim 10
Independent Claim
20 words
The method as claimed in claims 1 or 2 in which the removal of the solvent is effected under vacuum.
Claim 11
Independent Claim
24 words
The method as claimed in claims 1 or 2 in which the precipitated particles are washed with the non-solvent until free of the solvent.
Claim 12
Independent Claim
17 words
The method as claimed in claims 1 or 2 in which the solvent is an aliphatic alcohol.
Claim 13
Independent Claim
24 words
The method as claimed in claims 1 or 2 in which the solvent is selected from the group including methanol, ethanol, 1-propanol and 2-propanol.
Claim 14
Independent Claim
42 words
The method as claimed in claims 1 or 2 in which the polymer is a polyamide including as components having the formulae: --NH--(CH 2 ) 5 --CO--, --NH--(CH 2 ) 5 --NH--CO--(CH 2 ) 4 --CO--, and --NH--(CH 2 ) 11 --CO--.
Claim 15
Dependent Claim
19 words
The method as claimed in claim 3 in which the solvent is formic acid and the non-solvent is water.
Claim 16
Dependent Claim
94 words
The method as claimed in claim 3 in which the solvent is formic acid, the non-solvent is water; the mixture of formic acid and polymer is heated at approximately 60 degrees Celsius to form the solution; the solution is cooled to room temperature and distilled water is added to the solution; the resulting solution and distilled water is heated to approximately 60 degrees Celsius and thereafter cooled rapidly to precipitate the polymer as particles and isolated the precipitated particles are washed with an aliphatic alcohol to remove the formic acid and thereafter are dried.
Claim 17
Dependent Claim
25 words
The method as claimed in claim 2 in which the solution is cooled at a rapid rate to approximately 0 degrees Celsius subsequent to formation.
Claim 18
Dependent Claim
32 words
The method as claimed in claim 2 in which the solution is cooled subsequent to formation to approximately 0 degrees Celsius at a rate of cooling approximately one degree Celsius per second.
Claim 19
Independent Claim
23 words
The method as claimed in claims 1 or 2 in which the precipitated particles are redispersed in a dispersant medium subsequent to drying.
Claim 20
Independent Claim
40 words
The method as claimed in claims 1 or 2 in which fine particulate material is introduced as a component of the polymer/solvent mixture and the solution formed includes said fine particulate material, the precipitated particles comprise polymer-encapsulated fine particulate material.
Claim 21
Independent Claim
51 words
The method as claimed in claims 1 or 2 in which fine particulate material is introduced as a component of the polymer/solvent mixture and the solution formed includes said fine particulate material, the precipitated particles comprise polymer particles having said fine particulate material embedded in the surface of said polymer particles.
Claim 22
Independent Claim
71 words
The method as claimed in claims 1 or 2 in which fine particulate material is introduced as a component of the polymer/solvent mixture and the solution formed includes said fine particulate material dispersed therein, the fine particulate material comprises a pigment and the precipitated particles comprise polymer-encapsulated pigment particles, said particles capable of being dispersed in an electrical insulating dispersant medium to form a liquid toner for use in electrophotographic imaging.
Claim 23
Independent Claim
84 words
The method as claimed in claims 1 or 2 in which fine particulate material is introduced as a component of the polymer/solvent mixture and the solution formed includes said fine particulate material, the fine particulate material comprises a pigment and the precipitated particles comprise a polymer core having the pigment embedded in the surface thereof, said precipitated polymer particles with the pigment embedded thereon being isolated, dried and being capable of redispersal in a dispersant medium for use as liquid toner for electrophotographic imaging.
Claim 24
Independent Claim
99 words
A method for forming mono-dispersed particles of uniform size and morphology comprising the steps of: forming a solution of the polymer and a good solvent for the polymer by dissolving the polymer in said solvent; adding a non-solvent for the polymer to said solution; cooling said solution rapidly at a high cooling rate to precipitate the polymer particles from said solution as particles of generally uniform size and morphology; isolating the precipitated polymer particles; washing the isolated precipitated polymer particles to remove solvent and non-solvent therefrom; and drying the washed isolated precipitated polymer particles to form dry powder thereof.
Claim 25
Independent Claim
99 words
A method for forming mono-dispersed particles of uniform size and morphology comprising the steps of: forming a solution of the polymer and a good solvent for the polymer by dissolving the polymer in said solvent; adding a non-solvent for the polymer to said solution; cooling said solution rapidly at a high cooling rate to precipitate the polymer particles from said solution as particles of generally uniform size and morphology; isolating the precipitated polymer particles; washing the isolated precipitated polymer particles to remove solvent and non-solvent therefrom; and drying the washed isolated precipitated polymer particles to form dry powder thereof.
Claim 26
Dependent Claim
48 words
The method as claimed in claim 22 in which the polymer is a polyamide, the solvent is formic acid, distilled water is added to the solution subsequent to formation thereof and the precipitated particles are washed with aliphatic alcohol to remove the formic acid and the distilled water.
Claim 27
Independent Claim
28 words
The method as claimed in claims 22 or 23 in which the solution is formed by heating the mixture of the polymer and solvent for a predetermined duration.
Claim 28
Independent Claim
67 words
The method as claimed in claims 22 or 23 in which the solution is formed by heating a mixture of the polymer and solvent for a predetermined duration, the distilled water being added to the solution subsequent to reduction of the temperature thereof to room temperature, the solution thereafter being heated and thereafter being rapidly cooled at a high cooling rate to precipitate the polymer particles therefrom.
Claim 29
Independent Claim
21 words
The method as claimed in claims 22 or 23 in which the polymer is a polyamide having the formula [--NH--(CH.sub.2).sub.5 --CO--].
Claim 30
Independent Claim
22 words
The method as claimed in claims 22 or 23 in which the polymer is a polyamide having the formula [--NH--(CH.sub.2).sub.5 --NH--CO--(CH.sub.2).sub.4 --CO--].
Claim 31
Independent Claim
21 words
The method as claimed in claims 22 or 23 in which the polymer is a polyamide having the formula [--NH--(CH.sub.2).sub.g --CO--].
Claim 32
Independent Claim
15 words
The method as claimed in claims 22 or 23 in which the non-solvent is methanol.
Claim 33
Independent Claim
15 words
The method as claimed in claims 22 or 23 in which the non-solvent is acetone.
Claim 34
Independent Claim
27 words
The method as claimed in claims 22 or 23 in which the polymer is polystyrene, the solvent is cyclohexane and the non-solvent is an aliphatic isoparafinnic hydrocarbon.
Claim 35
Independent Claim
26 words
The method as claimed in claims 23 in which the solution is cooled rapidly to a temperature approximately 0 degrees Celsius to precipitate the polymer particles.
Claim 36
Independent Claim
45 words
The method as claimed in claims 22 or 23 in which the precipitated polymer particles are spherical, have a particle size about 10 micrometers, have a very high surface roughness and have a maximum deviation in size of at most 1.01 percent.mixture of said polymer.
References Cited (Backward Citations)
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| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1996-12-13 | 1997-06-14 | 1997-12-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-12-13 | 2001-06-14 | 2001-12-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-12-13 | 2005-06-14 | 2005-12-14 | $7700.00 | Window Closed / Lapsed |