TPU films can be classified by different methods. According to the soft segment structure, it can be divided into polyester TPU film, polyether TPU and polybutadiene type TPU, which respectively contain ester group, ether group or butenyl group; according to the isocyanate structure, it can be divided into yellow type (MDI) , TODI, NDI, PPDI, etc.) and non-yellowing type (HDI, H12MDI, etc.) are classified into urethane type and urethane type according to the hard segment structure, which are respectively obtained by diol chain extension or diamine chain extension.

According to the presence or absence of cross-linking, it can be divided into full thermoplastic and semi-thermoplastic. The former is a pure linear structure and has no crosslinks; the latter contains a small amount of crosslinks such as allophanate.

According to the synthetic process, it is divided into bulk polymerization and solution polymerization. In bulk polymerization, it can be divided into pre-polymerization method and one-step method according to the presence or absence of pre-reaction: pre-polymerization method is to react diisocyanate with macromolecular diol for a certain time. The TPU film is further added by adding a chain extender; the one-step method is to simultaneously mix the macrodiol, the diisocyanate and the chain extender into a TPU film. Solution polymerization is to dissolve the diisocyanate in a solvent, then add the macrodiol to react it for a certain period of time, and finally add the chain extender to produce