High-temperature insulation and method of manufacture

Claim 1

THE METHOD OF MAKING HIGH TEMPERATURE INSULATING BOARD IN WHICH A FLUFFY RESILIENT MASS OF LOOSE GLASS FIBERS IS COMPACTED UNDER PRESSURE TO HIGHER THAN ITS ORIGINAL DENSITY AND BONDED IN COMPACTED RELATION, WHICH COMPRISES APPLYING TO THE FIBERS OF THE MASS ABOUT THEIR JUNCTURES A THERMOSETTING PHENOL FORMALDEHYDE RESIN TO BIND THE FIBERS TOGETHER, COMPRESSING THE FIBROUS MASS TO COMPACTED RELATION WHILE HEATING THE SAID RESIN ON THE FIBERS FOR A TIME SUFFICIENT TO CURE THE RESIN AND THEREBY BOND THE FIBROUS MASS IN SAID COMPACTED RELATION, AFTER THE COMPLETION OF SAID HEATING OPERATION IMPREGNATING THE FIBROUS MATERIAL WITH AN AQUEOUS SUSPENSION OF BENTONITE AND DISTRIBUTING THE BENTONITE AS A DISCRETE LAYER OVER THE SAID RESIN ON THE FIBERS AND AROUND THE JUNCTURES OF THE FIBERS IN SAID MASS TO BIND THE FIBERS TOGETHER, THE BENTONITE BEING PRESENT IN SUFFICIENT AMOUNT TO HOLD THE FIBERS TOGETHER INDEPENDENTLY OF THE SAID RESIN, AND SUBJECTING THE BENTONITE ON THE FIBERS TO TEMPERATURES AT WHICH SAID RESIN BURNS OUT TO DRY THE BENTONITE AND THEREBY CONVERT IT TO A BINDER FOR THE FIBERS.