Method for preparing hydrophobic flame-retardant paper by adding in pulp

The invention discloses a method for preparing hydrophobic flame-retardant paper through in-pulp addition, belongs to the field of special paper manufacturing, and particularly relates to a preparation method of the hydrophobic flame-retardant paper. The preparation method comprises the following steps: preparing a microencapsulated flame retardant by using a sol-gel method to obtain a flame retardant coated by silicon dioxide shell microencapsulation; quantitatively weighing paper pulp according to the paper, and sequentially adding the microencapsulated flame retardant, aluminum sulfate, cationic dispersed rosin size, cationic polyacrylamide and bentonite; and uniformly mixing, sheet making, squeezing and drying to obtain the hydrophobic flame-retardant paper. The water contact angle of the flame retardant microencapsulated by the sol-gel method is increased, and the Zeta potential is reduced. The flame retardant is converted from hydrophilicity to hydrophobicity by the sol-gel method, so that the surface h