The invention relates to the technical field of filtering materials, in particular to a supporting material and a preparation method and application thereof. The material is composed of a PTFE paper base and a PTFE stretching film compounded on the surface of the PTFE paper base. The average pore size of the PTFE paper base is 1-20 microns, the
porosity is 50-85%, the PTFE paper base contains a
PTFE fiber skeleton and PTFE resin, and the
mass ratio of PTFE chopped fibers to long fibers in the skeleton is (1-3): (1-2); the average pore size of micropores of the PTFE stretching film is 0.1-10 microns, and the
porosity is 30-50%. The preparation method comprises the following steps: pulping part of PTFE chopped fibers to obtain first
slurry; the remaining chopped fibers and PTFE long fibers are mixed and defibered to obtain second
slurry, and the
mass ratio of the two parts of chopped fibers is set as required; mixing the two slurries with a functional additive, and performing wet molding, PTFE resin
emulsion surface
sizing,
dewatering and
drying to obtain a PTFE paper base; and hot-pressing and compounding a PTFE stretching film to obtain the supporting material. The supporting material is a full PTFE material, is free of impurities, low in cost and resistant to long-term
erosion of strong acid, strong alkali and strong corrosive gas, and the
corrosion resistance of the supporting material is equivalent to that of PFA; the
composite structure and formula can improve the
corrosion resistance, structural strength and filtering precision at low cost, and meet the high-precision filtering requirements of highly corrosive media such as
semiconductor etching liquid and the like.