▎ 摘　　要

NOVELTY - Preparing multilayer composite film involves using a base film and a composite layer, taking 10-15 pts. wt. of silicate, 8-10 pts. wt. of titanate, 60-80 pts. wt. of anhydrous ethanol, 10-15 pts. wt. of fatty acid, 20-30 pts. wt. of polylactic acid, 80-100 pts. wt. of tetrahydrofuran and 4-6 pts. wt. of graphene oxide. The polylactic acid is first dissolved and dispersed in tetrahydrofuran, and then graphene oxide, silicate, titanate, anhydrous ethanol and fatty acid are added, and the mixture is heated and refluxed for 3-5 hours, and then cast into a film and dried to obtain a dry film. The dried film is longitudinally stretching to 1.1-1.2 times the original length, and transversely to 1.1-1.2 times the original width, and then dipped the stretched film with a sodium hydroxide solution, and washed and dried to obtain the base film. The 8-10 pts. wt. of carboxymethyl chitosan, 100-120 pts. wt. of water, and 0.1-0.3 pts. wt. of chitosanase are sequentially taken. USE - Method for preparing multilayer composite film. ADVANTAGE - The method enables to prepare multilayer composite film, that can still maintain good mechanical properties after multiple foldings, etc., and no delamination or cracking is observed with the naked eye. DETAILED DESCRIPTION - Preparing multilayer composite film involves using a base film and a composite layer, taking 10-15 pts. wt. of silicate, 8-10 pts. wt. of titanate, 60-80 pts. wt. of anhydrous ethanol, 10-15 pts. wt. of fatty acid, 20-30 pts. wt. of polylactic acid, 80-100 pts. wt. of tetrahydrofuran and 4-6 pts. wt. of graphene oxide. The polylactic acid is first dissolved and dispersed in tetrahydrofuran, and then graphene oxide, silicate, titanate, anhydrous ethanol and fatty acid are added, and the mixture is heated and refluxed for 3-5 hours, and then cast into a film and dried to obtain a dry film. The dried film is longitudinally stretching to 1.1-1.2 times the original length, and transversely to 1.1-1.2 times the original width, and then dipped the stretched film with a sodium hydroxide solution, and washed and dried to obtain the base film. The 8-10 pts. wt. of carboxymethyl chitosan, 100-120 pts. wt. of water, and 0.1-0.3 pts. wt. of chitosanase are sequentially taken. After constant temperature stirring and enzymolysis for 1-2 hours, the enzyme is inactivated to obtain a hydrolyzed carboxymethyl chitosan dispersion, and added to the enzymatically degraded carboxymethyl chitosan dispersion 8-10% of polyethylene glycol phosphate. The enzymatically hydrolyzing carboxymethyl chitosan dispersion with 3-5 wt.% of p-phthalaldehyde, sheared and dispersed to obtain a coating film solution. The coating liquid is brushed on the surface of the base film, controlled the coating amount to 20-30 mg/cm2, and after the coating is completed, dried it at the temperature of 35-45 degrees C for 3-5 hours, and secondary coating, and then repeat coating 5-10 layers. After the last layer is coated, vacuum dry to constant weight to form a composite layer on the surface of the base film. After hot pressing, the material is discharged, that is, multi-layer composite film is obatined.