Electrical insulating material and method of making

Claim 1

THE PROCESS OF PREPARING A FLAME RETARDANT MOISTURE RESISTANT ELECTICAL INSULATION MATERIAL CONSISTING ESSENTIALLY OF, BY WEIGHT, 40 TO 60 PERCENT FIBROUS MATERIAL, 3 TO 27 PERCENT POLYVINYL CHLORIDE RESIN, 2 TO 11 PERCENT ANILINE-FORMALDEHYDE RESIN, AND 19 TO 40 PERCENT PHENOLFORMALDEHYDE RESIN, WHICH PROCESS COMPRISES (A) IMPREGNATING THE AFORESAID FIBROUS MATERIAL WITH A 10 TO 20 WEIGHT PERCENT SOLUTION OF PHENOL-FORMALDEHYDE RESIN, (B) CURING THE PRODUCT OF (A) AT ELEVATED TEMPERATURES, (C) IMPREGNATING THE PRODUCT OF (B) WITH A SOLUTION OF POLYVINYL CHLORIDE RESIN, ANILINE-FORMALDEHYDE RESIN AND PHENOL-FORMALDEHYDE RESIN CONTAINING FROM 10 TO 75 WEIGHT PERCENT OF POLYVINYL CHLORIDE RESIN AND FROM 25 TO 90 WEIGHT PERCENT OF ANILINE-FORMALDEHYDE AND PHENOLFORMALDEHYDE RESINS BASED ON THE TOTAL RESIN CONTENT OF THE SOLUTION, SAID ANILINE-FORMALDEHYDE RESIN BEING PRESENT IN THE RATIO OF FROM 0.25 TO 9 PARTS BY WEIGHT PER PART BY WEIGHT OF PHENOL-FORMALDEHYDE RESIN, AND (D) CURING THE PRODUCT OF (C) AT ELEVATED TEMPERATURES.