A filtration membrane material having excellent organic solvent resistance, a method for forming the filtration membrane, and a method for producing a bismaleimide-based polymer used in a filtration membrane material

摘要

A membrane filter material formed from a solvent resistant bismaleimide polymer which is formed by polymerizing a bismaleimide compound with a perhydrodiaza-type heterocyclic compound and has a main structural skeleton represented by the following formula: ##STR1## wherein R.sub.1, R.sub.2, R.sub.3 and R.sub.4 represents a lower carbon chain which is linear or contains a methyl group or ethyl group on the side chain, R.sub.5 represents a divalent group containing an aromatic ring, Y is R or N--R--N in which R is a lower carbon chain, and m is 0 or 1.PPThis bismaleimide polymer can be a membrane filter material having an excellent organic solvent resistance. When this polymer is formed into a hollow fiber or plain film, a high separating and filtering capacity and an excellent organic resistance can be attained. A membrane filter material having an enhanced organic solvent resistance is provided by preparing the bismaleimide polymer by reacting the bismaleimide compound and perhydrodiaza-type heterocyclic compound in a halogen-containing organic solvent in the presence of a small amount of a phenol.