TPU film modification method suitable for rainstorm-proof fabric

The invention discloses a TPU film modification method suitable for a rainstorm-proof fabric. The method comprises the steps that a TPU film is subjected to ultrasonic cleaning in ethyl alcohol, and the TPU film is put into a first sealing bag after being dried; adding a silane coupling agent KH-550 and hexadecane trimethoxy siloxane into a three-neck flask, then adding ethanol and distilled water, dispersing SiO2 with ethanol, then adding the SiO2 into the three-neck flask for reaction, drying, and then loading into a sealing bag II to obtain modified nano SiO2; the modified SiO2 powder is dispersed in an ethanol solvent, and SiO2 dispersion liquid is prepared; a TPU film is soaked in the SiO2 dispersion liquid for a reaction, then the TPU film is taken out and dried, and the modified TPU film is obtained. The water absorption rate of the TPU film can be effectively reduced, the problem that the rainstorm-proof performance of a composite fabric is reduced after long-term use due to the fact that the water ab