The invention discloses a preparation method of a
flame-retardant insulation board for a building exterior wall, and relates to a
building material prepared from a composition of
natural mineral materials. The method comprises the following steps: preparing an inorganic mineral nano
fiber powder panel matrix with an internal porous structure; preparing a
coating material for forming a heat reflecting layer on the upper surface of the panel matrix; preparing a
coating material for forming a heat
radiation layer on the lower surface of the panel matrix; respectively
coating the coating material of the heat reflecting layer and the coating material of the heat
radiation layer on the upper surface and the lower surface of the inorganic mineral nano
fiber powder panel matrix to form the heat reflecting layer and the heat
radiation layer respectively, and then naturally airing, so as to prepare the
flame-retardant insulation board product for the building exterior wall. The defects that the existing insulation board for the building exterior wall is poor in thermal insulating property, and easy to burn, so as to form a potential safety
hazard, and the preparation technology and the required conditions are complicated are overcome.