METHOD OF PREPARING MICROCAPSULES Russian patent published in 1998 - IPC

FIELD: physico-chemical procedures. SUBSTANCE: invention relates to preparing microcapsules whose nuclei consist of liquid-phase material with restricted solubility in water. Method includes microcapsulation by way of emulsifying nuclear material in gelatin solution, adding agents reducing solubility of gelatin, depositing the latter onto the surface of emulsion drops followed by hardening polymer shells formed. Bearing in mind preparing mononuclear microcapsules with low permeability and high heat resistance of polymer shells, secondary shells are formed on primary microcapsule gelatin shells via consecutively treating microcapsules by (i) polyacrylic acid solutions in amount 8 to 80% based on the weight of primary shell at pH below isoionic point of gelatin, (ii) polyvalent metal salts in amount no less than equivalent amount relative to polyacrylic acid, while acidity of medium falls to values providing completeness of metal- polyacrylic acid reaction, and (iii) inactivators in amount at least 3 mol % based on amount of metal salt utilized. EFFECT: reduced permeability and increased heat resistance. 1 tbl