The Synthesis Of Isomeric Bisether Dianhydride And Application For Polyimide

Polyimides (PI) are a class of integrated high-performance engineering plastics. With outstanding heat resistance and superior mechanical properties, the decomposition temperature of all-aromatic PI gets more than500℃. Usually tensile strength of unfilled PI can be achieved by100MPa. Since Kapton as industrial production has been available commercially by DuPont on60s of the last century, PI is widely used in aviation, aerospace, micro-electronics industry and other fields.All polyimides Contain structure of phthalimide ring. Ordinary studies have shown that isomeric anhydride have a significant impact on the nature of the polyimide. In this paper, we accomplish the synthesis of N-methyl-4-nitro-phthalimide (4-NPI)(purity99.62%) and N-methyl-3-nitro-phthalimde (3-NPI)(purity99.91%) directly from Phthalic Anhydride, that solve the separation problem of3-NPI by avoiding Fractionation. At the same time, we develop a route that methylamine aqueous solution reacting with substituent or nonsubstituent phthalic anhydride in acetic acid solution to substituent or nonsubstituent N-methyl-phthalimide as the general approach.Comparing Nitrophthalimido and chlorinated anhydride route in preparation of4,4bisphenol A bis(ether) phthalimide (4,4’-BPADI), the thress different aspects among isomer’s preparation, reaction process and production costs show that:Nitrophthalimido route has wide variety of sources of raw materials, low cost and following the trend of green chemistry, so it has a prospect for industrialization.We synthesize4,4’-bisphenol A-bis(ether) dianhydride (4,4’-BPADA) which melting point189.2-190.3℃. NMR and IR confirmed the structure. And the purity reachs99.73%with test of HPLC.160,000yuan/ton of cost is obtained by preliminary accounting. First synthesis of3,3’-bisphenol-A bis(ethe)r dianhydride (3,3’-BPADA),1H NMR,13C NMR and IR spectra comfirmed the structural identification.3,3’-BPADA of melting point is 186.3-187.1℃.The purity reachis99.24%(HPLC), the results of the preliminary cost accounting is about160thousand yuan/ton.After completing the synthesis of4,4’-BPADA-ODA polyamic acid, polyamic acid on8-hour time reaction at10℃obtained the greatest intrinsic viscosity. Film tensile strength is the best for4,4’-BPADA-ODA polyimide with thermal imidization process of60℃/10h,100℃/1h,200℃/1h,300℃/2h heating programming. Film tensile strength is the best for4,4’-BPADA-PPD witg thermal imidization process of60℃/10h,100℃/1h,200℃/1h,350℃/2h heating programming.3,3’-/4,4’-PI is short for3,3’/4,4’-BPADA polyimide that prepared by-,3,3’-/4,4’-bisphenol A-bis(ether) dianhydride (3,3’-/4,4’-BPADA) with p-phenylenediamine (PPD),4,4’-diamino-2benzene methane (MDA),4,4’-diamino-diphenyl ether(ODA) and1,6-hexamethylene diamine(HDA).3,4’-PI is short for copolymer of3,3’-BPADA and4,4’-BPADA with diamines. The results showed that:solubility of isomeric polyimides in common solvents meet the3,3’->3,4’->4,4’-law, while BPADA-MDA has a strong solvent resistance.4,4’-BPADA-MDA in the concentrated sulfuric acid remain part of the membrane structure. Glass transition temperature (Tg) of isomeric polyimide showed33,3’->3,4’->4,4’-law. Sub-transition temperature (Tp) Display:4,4’-have significant sub-shift.3,4’-PI only have weak peak polyimide.3,3’-PI is completely unobservable. mechanical properties:4,4’-BPADA-MDA modulus increase above the glass transition temperature because the crystallization of the polymer chain arising. All the3,3’-polyimide modulus decrease slowly in high-temperature. Tensile strength of3,3’-BPADA-ODA and3,3’-BPADA-MPD is higher than the corresponding4,4’-type-performance. Heat-resistant:For heat resistance of rigid Amine BPADA-PPD,3,3’->3,4’->4,4’-consist with general law. BPADA-ODA and BPADA-MPD of3,4’-polyimide at a high temperature weight loss slowed down. And3,4-Polyimide5%weight loss temperature was significantly higher than3,3’-and4,4’-BPADA-MDA PI is a kind of Polyimide with solvent resistant, high glass transition temperature.3,3’-BPADA-MDA have tensile strength in almost100MPa, tensile modulus of3.2GPa and glass transition temperature at314℃.3,4’-BPADA-MDA to retain most of the modulus and tensile strength at the same condition with outstanding heat resistance,5%weight loss at488℃.3,3’-BPADA-ODA is a similar type of Ultem polyimide product with modulus of2.4GPa, tensile strength in97MPa, glass transition temperature at259℃,5%loss temperature at501℃and soluble in DMAc, DMF, NMP and other solvents, which is a kind of material with excellent mechanical properties and molding ability in solution.