The preparation method of the film is as follows: after the polyamic acid solution is cast into a film and stretched, it is imidized at a high temperature. The film is yellow and transparent, with a relative density of 1.39 ～ 1.45. It has outstanding high temperature resistance, radiation resistance, chemical corrosion resistance and electrical insulation properties. It can be used for a long time in the air at 250 ～ 280 ℃. The glass transition temperatures are 280 ° C (Upilex R), 385 ° C (Kapton) and above 500 ° C (Upilex S). The tensile strength is 200 MPa at 20 ° C and greater than 100 MPa at 200 ° C. It is especially suitable for flexible printed circuit board base material and various high-temperature resistant motor and electrical insulation materials.
Physical properties
Thermosetting polyimide has excellent thermal stability, chemical resistance and mechanical properties, usually orange. The flexural strength of graphite or glass fiber reinforced polyimide can reach 345 MPa, and the flexural modulus reaches 20GPa. The thermosetting polyimide has little creep and has high tensile strength. The temperature range of polyimide covers a wide range, from minus one hundred degrees to two or three Baidu.
Chemical properties
Polyimide is chemically stable. Polyimide can prevent burning without adding flame retardant. General polyimides are resistant to chemical solvents such as hydrocarbons, esters, ethers, alcohols and chlorofluorocarbons. They are also resistant to weak acids but are not recommended for use in strong alkaline and inorganic acid environments. Some polyimides such as CP1 and CORIN XLS are soluble in solvents, this property helps to develop their applications in spray coating and low temperature crosslinking.