Process for producing a microcapsule
Abstract
Abstract Disclosed herein a process for producing a microcapsule having an excellent solvent-resistance and a thermal stability, and an extremely minute amount of unreacted formaldehyde, comprising the steps of dispersing a substance to be encapsulated into an aqueous solution containing a water-soluble cationic urea resin, at least one prepolymer selected from the group consisting of a melamine-formaldehyde prepolymer, a urea-formaldehyde prepolymer and a melamine-urea-formaldehyde prepolymer and an anionic surfactant and then, adding an acid-catalyst into the thus obtained aqueous dispersion thereby forming a wall membrane which encapsulates the dispersed microparticle of the substance to be encapsulated by polycondensing the prepolymer and the cationic urea resin followed by cross-linking while causing complex coacervation, and adding a monosaccharide into the aqueous dispersion while adjusting the pH of the aqueous dispersion with the addition of a hydroxide of an alkaline earth metal thereby removing the unreacted residual formaldehyde remaining in the aqueous dispersion.
Inventors
- 👤 Yuriko Igarashi
- 👤 Yoshio Okada
Bibliographic Details
Claims Analysis
Total Claims: 7References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-07-17 | 1988-01-16 | 1988-07-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-07-17 | 1992-01-16 | 1992-07-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-07-17 | 1996-01-16 | 1996-07-17 | $7700.00 | Window Closed / Lapsed |