초록 ▼

An aromatic condensation polyimide film that is approximately 90% transparent at 500 nm, useful for thermal protective coatings and the like and the process for preparing same are disclosed. An essential feature of the invention for achieving maximum optical transparency films requires utilizing rec

An aromatic condensation polyimide film that is approximately 90% transparent at 500 nm, useful for thermal protective coatings and the like and the process for preparing same are disclosed. An essential feature of the invention for achieving maximum optical transparency films requires utilizing recrystallized and/or sublimated specific aromatic diamines and dianhydride monomers and introducing bulky electron-withdrawing groups and separator groups into the polymer molecular structure. The incorporation of bulky electron-withdrawing groups in the diamine portion of the polymer structure serves to reduce the formation of inter-chain and intra-chain charge transfer complexes which normally cause large absorptions in the UV-visible range. Incorporation of separator atoms into either the diamine or dianhydride monomers serves to reduce the amount of conjugation and inter-and intra-chain electronic interactions and thereby lessen charge transfer complex formation.

대표청구항 ▼

A method for preparing a high temperature, highly optically transparent-to-colorless aromatic polyimide film comprising: chemically reacting equimolar quantities of (1) a highly purified aromatic diamine and (2) a highly purified aromatic dianhydride, in a solvent medium to form a high molecular wei

A method for preparing a high temperature, highly optically transparent-to-colorless aromatic polyimide film comprising: chemically reacting equimolar quantities of (1) a highly purified aromatic diamine and (2) a highly purified aromatic dianhydride, in a solvent medium to form a high molecular weight polyamic acid solution, at least one of the highly purified, aromatic diamine and the highly purified aromatic dianhydride containing a bulky electron-withdrawing group in the monomer molecular structure, applying a desired thickness film layer of the polyamic acid solution onto a surface, thermally curing the applied film in the temperature range of 250°C. to 300°C. for at least one hour to yield an optically transparent polyimide film layer.