Method for preparing pyrohydrolysis resisting polyimide fiber filter material

The invention relates to a method for preparing a pyrohydrolysis resisting polyimide fiber filter material. The method is characterized by comprising the following steps of: padding a polyimide fiber three-layer structural body which is prepared by a non-weaving technology and serves as a filter material blank by using pyrohydrolysis resisting finishing liquor which is mainly prepared from polytetrafluoroethylene emulsion and epoxy phenolic resin; performing low-temperature migration prevention preliminary drying and high-temperature cross-linking baking to ensure that a membrane structure of polytetrafluoroethylene particles which are completely coated and uniformly dispersed is formed on the surface of a filter material fiber; and isolating high-temperature water vapor from being contacted with the fiber to obtain the filter material. The prepared filter material has the longitudinal and horizontal breaking strength retention rate of 100 percent to 111 percent when hydrolysed at a high continuous working te