Method of manufacturing a felted fibrous mat

Claim 1

IN THE METHOD OF FORMING A FELTED FIBROUS MAT COMPRISING THE STEPS OF: (A) CONTINUOUSLY AND CONCURRENTLY DEPOSITING ON A MOVING PLANAR SUPPORT A FIRST LAYER PORTION OF CHOPPED GLASS STRANDS, SAID STRANDS CONSISTING OF A MULTIPLICITY OF MONOFILAMENTS, WHICH STRANDS IN SAID FIRST LAYER PORTION HAVE BEEN INTENTIONALLY FRAYED AT THEIR EXTREMITIES INTO A NUMBER OF THEIR COMPOSITE MONOFILAMENTS, AND A HEAT SETTABLE RESIN BINDER THEREFOR TO PROVIDE A FIRST LAYER THEREOF WEIGHING ABOUT 1/10 TO 6/10 OUNCE PER SQUARE FOOT; (B) CONTINUOUSLY AND CONCURRENTLY DEPOSITING OVER SAID FIRST LAYER A SECOND LAYER PORTION COMPRISING A PLURALITY OF HIGH STRENGTH CHOPPED GLASS FIBER STRANDS CONSISTING OF A MULTIPLICITY OF MONOFILAMENTS GENERALLY LINEARLY ARRANGED WITH RESPECT TO EACH OTHER, SAID STRANDS IN SAID SECOND LAYER PORTION IN SUBSTANTIALLY NON-FRAYED FORM AS COMPARED TO THE STRANDS OF SAID FIRST LAYER PORTION, AND A HEAT SETTABLE RESIN BINDER FOR SAID STRANDS OF SAID SECOND LAYER; (C) CONTINUOUSLY AND CONCURRENTLY DEPOSITING OVER SAID SECOND LAYER A THIRD LAYER PORTION WEIGHING ABOUT 1/10 TO ABOUT 6/10 OUNCE PER SQUARE FOOT OF CHOPPED FRAYED STRANDS SUBSTANTIALLY SIMILAR TO THOSE OF SAID FIRST LAYER PORTION, AND A RESIN BINDER THEREFOR, THE IMPROVEMENT IN CONNECTION THEREWITH OF FRAYING SAID FIRST AND THIRD LAYER CHOPPED STRANDS AT THEIR EXTREMITIES INTO A NUMBER OF THEIR COMPOSITE MONOFILAMENTS PRIOR TO THEIR RESPECTIVE DEPOSITIONS AND INTERLACING A NUMBER OF THE FRAYED STRANDS OF SAID FIRST AND THIRD LAYER PORTIONS WITH A NUMBER OF THE STRANDS ON THE OPPOSITE SURFACES OF SAID SECOND LAYER PORTION.