Patent attributes
Provided is a continuous production method of a polyamide with stabilized polymerization degree and good quality, particularly an aromatic-containing polyamide. A continuous production method of a polyamide, comprising (a) a raw material preparation step of individually melting a diamine and a dicarboxylic acid, or producing a salt of amine and carboxylic acid in water, (b) a raw material introduction step of continuously introducing the prepared raw materials into a tubular reaction apparatus, (c) an amidation step of passing the introduced raw materials through the tubular reaction apparatus, thereby effecting amidation to obtain a reaction mixture containing an amidated product and a condensed water, (d) an initial polymerization step of introducing the reaction mixture into a continuous reaction apparatus capable of separation and removal of water, and elevating the polymerization degree while separating and removing water at a temperature higher than the melting point of the finally obtained polyamide to obtain a polyamide prepolymer, and (e) a final polymerization step of introducing the polyamide prepolymer into a continuous reaction apparatus capable of separation and removal of water, and further elevating the polymerization degree at a temperature higher than the melting point of the finally obtained polyamide to obtain a polyamide adjusted to a desired relative viscosity [RV].
