METHOD OF MANUFACTURING HOLLOW MICROSPHERES Russian patent published in 1999 - IPC

FIELD: polymer materials. SUBSTANCE: hollow microspheres are manufactured by mixing liquid resole phenol-formaldehyde resin, expanding agent, and surfactant, heating mixture to decompose expanding agent and spraying it into preheated gas medium to form microspheres that are then hardened and dried. Novelty in such process is that, to preliminarily mixed expanding agent and surfactant, water is added as dispersing agent in amount from 0.01 to 150 weight parts per 100 weight parts of expanding agent and, before addition to phenol-formaldehyde resin, mixture is agitated to impart fine state. EFFECT: decreased density of microspheres. 2 cl, 1 tbl, 8 ex