ELECTRET PRODUCTION PROCESS Russian patent published in 1996 - IPC

FIELD: sources of external electric fields, manufacture of diaphragms, condenser microphones, energy storage cells, etc. SUBSTANCE: electret production process involves exposure of polymeric film material to corona discharge field; used as polymeric material is polyethylene terephthalate film coated with copolymer or vinyl chloride and vinyl acetate subjected to heat treatment at 90 to 120 C for 40 to 120 min, this being followed by exposure to corona discharge field at 25-45 kV and polarization time of 60-120 s in the course of cooling down; coating on polyethylene terephthalate film is formed from 5-7& solution of copolymer in acetone to obtain electrets with initial electret potential difference 15 times higher than that of prototype and higher stability of charge with time. EFFECT: improved value and time stability of charge. 1 tbl