Outlook: As promising polyimide polymer material has been fully recognized, in the insulating material and the material aspects of the application structure is constantly expanding. In terms of functional materials are emerging, their potential is still excavations. But after 40 years of development it has not yet become a bigger breed, mainly because, compared with other polymers, the cost is too high. Thus, one of the main directions of future research should continue to be the polyimide in the monomer synthesis and polymerization process to find ways to reduce costs.
1. Synthesis of monomers: polyimide monomer is a dianhydride (D acid) and diamine. Diamine synthesis method is relatively mature, there are many diamine supply of goods. Dianhydride monomer is rather special, in addition to use as a curing agent for epoxy resin are mainly used for polyimide synthesis. Pyromellitic dianhydride and trimellitic anhydride can be heavy aromatic petroleum product refining oil extracted durene and partial three toluene vapor and liquid phase oxidation step to give. Other important dianhydride, benzophenone dianhydride, biphenyl dianhydride, diphenyl ether dianhydride, hexafluoro dianhydride synthesized by various methods, but the cost is very expensive, such as hexafluoro dianhydride kg reached the upper million. Changchun Institute of Applied Chemistry developed by o-xylene chlorination, oxidation and then isomerization separation can be obtained high purity 4-chloro-3-chloro anhydride and phthalic anhydride, with these two compounds can be synthesized as a raw material series dianhydride, its great potential for cost reduction is a valuable synthetic route.
2. polymerization process: currently used two-step, one-step polycondensation process uses a high-boiling solvent, aprotic polar solvents higher price, it is difficult divisible, eventually requires high temperature processing. PMR method using cheap alcohol solvent. You can also use a thermoplastic polyimide dianhydride and a diamine polymerized directly in an extruder granulation, the solvent is no longer needed, can greatly improve efficiency. Anhydride with a chlorinated without going through dianhydride, and the diamine, bisphenol, sodium sulfide or elemental sulfur directly polymerized polyimide is the most economical synthetic route.
3. Processing: the application of polyimide surface is so wide, the processing is also a wide variety of requirements, such as high uniformity of deposition, spinning, vapor deposition, submicron lithography, deep straight wall engraved eclipse, large area, high volume molding, ion implantation, laser precision machining, nano-hybrid technology, and so are the application of polyimide open vast world.
With a significant reduction in synthesis technology to further improve the processing technology and cost, but also has excellent mechanical properties, electrical insulation properties, thermoplastic polyimide will show its more prominent role in the field of future materials. The thermoplastic polyimide and its good workability and more promising.