Method for preparing hygroscopic film

The embodiment of the invention discloses a method for preparing a hygroscopic film. Polyvinylalcohol, glycerol and water are mixed and heated to form hydrogel, wherein the polyvinylalcohol is used as a substrate. The polyvinylalcohol and the glycerol comprise a large number of hydroxide radicals which are easy to hold gaseous water molecules in air so as to fulfill the aim of absorbing moisture.The glycerol and the water are used for endowing the polyvinylalcohol with flexibility under the heating condition, so the prepared hygroscopic film has flexibility. Polymethylacrylic acid has a spacial network structure; carboxyl groups in molecular chains absorb the gaseous water molecules in the air first; and then the water molecules enter the internal spacial network; therefore, the water molecules in the air are continuously absorbed until balance. Compared with the prior art, the method has the advantages of simple and easily controllable operation; and experiment results show that theprepared hygroscopic film