PROCESS FOR THE SUPERFICIAL TREATMENT OF A FIBROUS, NON-WOVEN AND VERY ACOUSTIC FILTERING LAYER, FORMING ELECTRET AND ITS APPLICATION TO FILTERS AND RESPIRATORY MASKS, IN PARTICULAR

摘要

P THE PROCESS OF THE INVENTION RESIDES IN THAT SMOOTH SURFACES OF THIS LAYER ARE SMOOTHED BY EXERCISING LIGHT FRICTION AT LOW PRESSURE SO THAT THE HIGHLY SELECTIVE FIBERS ARE LAID ON THE UNDERLYING FIBROUS MASS WITHOUT THAT THIS IS TO BE COMPRESSED, THE FRICTION BEING EXERCISED AT A TEMPERATURE OF RAMOLLISSEMENT SUCH AS THE SURFACE FIBERS WELD BETWEEN THEM TO FORM A SKIN OR POROUS GLACIS. PREFERABLY, SMOOTHING IS CARRIED OUT BY MEANS OF A METAL MASS WITH A TEMPERATURE BETWEEN 115 AND 150 ° C. / P P THIS METHOD MAY APPLY TO THE OUTER FACE OF A FILTERING RESPIRATORY MASK CONSISTING OF ENVELOPE IN THIS FIBROUS MATERIAL COVERING A RELATIVELY RIGID POROUS SHELL FOR THE PROTECTION OF THE SKIN; IT CAN ALSO APPLY TO AT LEAST ONE OF THE FILTERING LAYER FACES EQUIPPED WITH ANY FILTERS. / P