Heat resistant and flame resistant papers

A hot pressed, heat resistant and flame resistant paper containing from 60 to 99.5 percent by weight of infusible, non-flammable phenolic fibers having fiber lengths in the range of 0.3 to 100 mm and from 0.5 to 30 percent by weight of a hardened epoxy resin as a binder, said phenolic fibers having been prepared by either (1) immersing novolak fibers in a first aqueous solution containing 0.1 to 25 percent by weight of a strong acid and 0.5 to 35 percent by weight of an aldehyde at room temperature for zero to 2 hours, raising the temperature of the first solution to from 50.degree. to 105.degree. C in from 0.50 to 10 hours and then maintaining the first solution at from 50.degree. to 105.degree. C for from zero to 2 hours to harden the outer layer of the fibers, then immersing the fibers in a second aqueous solution containing 0.2 to 15 percent by weight of ammonia or amines and one to 35 percent by weight of an aldehyde at room temperature, then raising the temperature of said second solution to 70.degree. to 95.degree. C in from 0.5 to 1 hour and then maintaining the solution at 70.degree. to 95.degree. C for 0.5 to 10 hours until the weight of the starting novolak fibers are increased from 3 to 30 percent by weight as a result of cross-linking, or (2) immersing novolak fibers in said first solution at room temperature for zero to 2 hours, raising the temperature of said first solution to 50.degree. to 105.degree. C in from 0.05 to 10 hours and then maintaining said first solution at 50.degree. to 105.degree. C for zero to 20 hours until the weight of the starting novolak fibers has increased from 3 to 30 percent by weight as a result of cross-linking,

• said epoxy resin being an addition product of a bisphenol or a halogenated bisphenol with epichlorohydrin.