Patent US4297235A successfully refreshed from Google Patents.
US4297235A
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US
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Method of preparing a microcapsule dispersion
Assignee: Fujifilm Holdings Corp
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Filing: 1979-11-05
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Granted: 1981-10-27
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Expires: 1999-11-05
Abstract
Abstract A method of preparing a dispersion of microcapsules whose walls comprise formaldehyde as one of the wall components characterized by adding urea, a sulfite or a hydrogensulfite to said dispersion.
Inventors
- 👤 Yoshiyuki Hoshi
- 👤 Takayuki Hayashi
- 👤 Fujio Kakimi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 22:39
CPC Classifications
B; B01; B01J; B01J13/00; B01J13/02; B01J13/20; Y; Y10; Y10S; Y10S428/00; Y10S428/914
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
97 words
In a method of preparing a dispersion of microcapsules whose walls comprise formaldehyde as one of the wall components, the improvement which comprises preparing a dispersion containing microcapsules with microcapsule walls of an amino-formaldehyde condensation resin, adding urea to the capsule dispersion in the range from about 1/10 to 5 times greater on a molar basis than the formaldehyde contained in the dispersion, heating the capsule dispersion with stirring, and adding a solution of sulfite, hydrogensulfite or a mixture thereof to the capsule dispersion in the range from about 0.02 to 1 mol per mol of formaldehyde.
Claim 2
Dependent Claim
97 words
In a method of preparing a dispersion of microcapsules whose walls comprise formaldehyde as one of the wall components, the improvement which comprises preparing a dispersion containing microcapsules with microcapsule walls of an amino-formaldehyde condensation resin, adding urea to the capsule dispersion in the range from about 1/10 to 5 times greater on a molar basis than the formaldehyde contained in the dispersion, heating the capsule dispersion with stirring, and adding a solution of sulfite, hydrogensulfite or a mixture thereof to the capsule dispersion in the range from about 0.02 to 1 mol per mol of formaldehyde.
Claim 3
Dependent Claim
18 words
The method of claim 1, wherein said sulfite and/or hydrogensulfite is potassium, sodium or ammonium sulfite or hydrogensulfite.
Claim 4
Dependent Claim
25 words
The method of claim 1, wherein after adding urea to the dispersion, the dispersion is heated at a temperature of about 40° to 80° C.
Claim 5
Dependent Claim
27 words
The method of claim 3, wherein said dispersion is heated for a time sufficient to remove about 50 to 80% of the residual formaldehyde in said dispersion.
Claim 6
Dependent Claim
17 words
The method of claim 1, wherein said urea is added to said dispersion as an aqueous solution.
Claim 7
Dependent Claim
17 words
The method of claim 1, wherein the pH of said urea-containing dispersion is about 2.0 to 5.0.
Claim 8
Dependent Claim
16 words
The method of claim 1, wherein said urea is added to said dispersion as a powder.
Claim 9
Dependent Claim
27 words
The method of claim 1, wherein said method includes heating said sulfite and/or hydrogensulfite-containing dispersion for a time sufficient to remove substantially all formaldehyde from the dispersion.
Claim 10
Dependent Claim
19 words
The method of claim 1, wherein the pH of said sulfite and/or hydrogensulfite-containing dispersion is about 6 to 11.
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) | 1984-10-26 | 1985-04-27 | 1985-10-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-10-26 | 1989-04-27 | 1989-10-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-10-26 | 1993-04-27 | 1993-10-27 | $7700.00 | Window Closed / Lapsed |