POLYIMIDE RESIN BELT

PURPOSE:To ensure that a belt of polyimide resin having a repeatability unit expressed by a specific general formula is highly heat-resistant and durable by thermally sealing both ends of the belt. CONSTITUTION:Polyimide having a repeatable structural unit expressed by formula I (X is a directly linked 1 to 10C divalent hydrocarbon group, inpropyridene hexafluoride group, carbonyl group, thio group or sulfonyl group; R is a quatrivalent group selected from among non-condensed polycyclic aromatic groups, each consisting of a 2C or more aliphatic group, cyclic aliphatic group, monocyclic aromatic group, condensed polycyclic aromatic group and aromatic group linked to each other directly or by a cross-linking member), is thermally treated within a temperature range of 250 to 370 deg.C. Consequently, polyimide pellets, each having a crystallization degree of 5% or higher under normal conditions, are obtained. The belt is manufactured within a molding temperature of 300 to 450 deg.C using the polyimide pellet with the help of a fusion extrusion molding machine. Thus the form belt can be made endless by overlapping the ends and thermally sealing them.