Friction material

Claim 1

THE METHOD OF MAKING AUTOMOTIVE TRANSMISSION FRICTION MATERIAL OF POROUS RESILIENT CHARACTER FOR USE IN OIL, WHICH COMPRISES WET FELTING AN AQUEOUS SLURRY CONSISTING ESSENTIALLY BY WEIGHT OF FROM ABOUT 35% TO ABOUT 85% ASBESTOS FIBERS, FROM ABOUT 10% TO ABOUT 50% WOOD PARTICLES PASSING A 20 MESH SIZE SIEVE, FROM ABOUT 1% TO ABOUT 4% OF REINFORCING CELLULOSE FIBERS, FROM ABOUT 1% TO ABOUT 4% BY WEIGHT OF SIZING MATERIAL AND UP TO ABOUT 10% FRICTION MODIFYING AGENTS, DRYING THE RESULTANT SHEET MATERIAL UNTIL IT HAS A CONSTANT WEIGHT AT 225*F., IMPREGNATING IT WITH A VOLATILE SOLVENT SOLUTION OF HEAT SETTING ORGANIC BINDER TO INCORPORATE THEREIN FROM ABOUT 15% TO ABOUT 40% OF SAID BINDER BY WEIGHT OF THE PRE-DRIED SHEET, AIR DRYING THE IMPREGNATED SHEET TO SUBSTANTIALLY EVAPORATE THE SOLVENT CONTENT AND TO LEAVE A POROUS STRUCTURE BY EVAPORATION OF THE SOLVENT, AND THEREAFTER HEAT CURING SAID BINDER CONTENT.