Patent ID: 8846852
Filing Date: 2014-09-30
Classification: C08G,C08J,C09D,C09K

Abstract:
1. A polyimide film obtained from an imide of polyamic acid, said polyamic acid being obtained by polymerizing diamines and acid dianhydrides, wherein an absolute molecular weight is 30,000 to 170,000, and the absolute molecular weight is determined by the following Formula 1: wherein, R K*=4π c is a polymer concentration (g/ml) in a solution; M is molar mass, and weight average molecular weight (Mw) in the case of polydisperse sample; A P(θ)=R wherein said acid dianhydrides comprise (i) 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride, and (ii) at least one selected from the group consisting of 4-(2,5-dioxotetrahydrofuran-3-yl)-1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic anhydride, 4,4′-(4,4′-isopropylidenediphenoxy)bis(phthalic anhydride), pyromellitic dianhydride, biphenyltetracarboxylic dianhydride, and oxyphthalic dianhydride; 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride is introduced to a polymerization mixture last in the order of introducing the acid dianhydrides; and wherein the polyimide film is obtained by further heating after making film.