| 摘要 |
<p>A process for the preparation of stable suspensions and powders of stable microcapsules containing at least one active material having a variable porosity comprising preparing a colloidal solution of equal parts by weight of gelatin and acacia gum with a total concentration of 4 to 6% by weight of the final emulsion, preparing an oil solution, suspension or emulsion of the active material at a concentration of 1 to 5% by weight of the final emulsion and containing a variable amount of organosoluble ethyl hydroxyethylcellulose, mixing the said two compositions with stirring at a temperature near 50 DEG C. in the presence of an emulsifying agent to form an "oil in water" emulsion, effecting consecutively coacervation and microencapsulation of the emulsified droplets containing the active material by adjusting the pH to 4.2 to 4.4 by addition of an acid and then cooling the mixture to about 20 DEG C. with stirring, reticulating the walls of the formed microcapsules by reaction with glutaric aldehyde and tannin with stirring at about 20 DEG C. and either forming a concentrated suspension of microcapsules by slow addition at 20 DEG C. of a water soluble ethyl hydroxyethylcellulose to the eticulated microcapsules or adding an antiagglomeration agent with stirring to the reticulated microcapsules at 20 DEG C. and drying the resulting powder and the microcapsules produced thereby which are stable with respect to physico chemical influences and to exterior elements generally, such as sunlight and temperature changes so that the encapsulated active material maintains its activity.</p> |
