Flame resistant cellulosic materials

Claim 1

A PROCESS FOR TREATING A CELLULOSIC MATERIAL WHICH COMPRISS: (A) TREATING SAID CELLULOSIC MATERIAL WITH AN AQUEOUS SOLUTION OF A FURTHER-POLYMERIZABLE METHYLOL PHOSPHORUS POLYMERIC MATERIAL CONTAINING AT LEAST ONE FREE METHYLOL GROUP ATTACHED TO A PHOSPHORUS ATOM PREPARED BY TREATING A PRECONDENSATE CONSISTING OF A PARTIALLY POLYMERIZING MIXTURE OF A PHOSPHORUS-CONTAINING COMPOUND SELECTED FROM THE GROUP CONSISTING OF TETRAKIS(HYDROXYMETHYL) PHOSPHONIUM CHLORIDE AND TRIS(HYDROXYMETHYL) PHOSPHINE OXIDE AND A WATER-SOLUBLE AMIDE SELECTED FROM THE GROUP CONSISTING OF TRIS(2-CARBAMOYLETHYL) AMINE AND ETHYL CARBAMATE, SAID AQUEOUS SOLUTION CONTAINING FROM ABOUT 20 TO 30% OF THE PHOSPHORUS-CONTAINING COMPOUND AND FROM ABOUT 5 TO 10% OF THE WATER-SOLUBLE AMIDE AAND BEING BUFFERED TO A PH OF FROM ABOUT 3.5 TO ABOUT 6.5 WITH AQUEOUS AMMONIUM ACETATE; (B) DRYING THE THUS-TREATED CELLULOSIC MATERIAL AT A TEMPERATURE OF FROM ABOUT ROOM TEMPERATURE TO ABOUT 170*C., FOR A PERIOD OF TIME FROM ABOUT 1 MINUTE TO ABOUT 4.75 MINUTES, THE LONGER PERIOD OF TIME BEING APPLICABLE TO THE LOWER TEMPERATURE; (C) EXPOSING THE DRIED, TREATED CELLULOSIC MATERIAL TO GASEOUS AMMONIA FOR A PERIOD OF TIME FROM ABOUT 1/2 MINUTE TO ABOUT 2 MINUTES, FROM ABOUT 25*C. TO ABOUT 100*C.; (D) IMMERSING THE AMMONIA GAS-TREATED CELLULOSIC MATERIAL IN A 1%-28% AQUEOUS AMMONIA SOLUTION FOR A PERIOD OF TIME FROM ABOUT 1/2 MINUTE TO ABOUT 5 MINUTES, AT ROOM TEMPERATURE; THEN (E) WASHING, AND DRYING THE RESULTING CELLULOSIC MATERIAL.