Production method of crystalline polyamide resin

Abstract

There is provided a production method of a crystalline polyamide resin by thermal polycondensation of a mixture including at least a diamine component, a dicarboxylic acid component and water as a starting material, wherein the diamine component includes (A) pentamethylene diamine at a ratio that is equal to or greater than 10 mol % and less than 80 mol % relative to a gross amount of the diamine component; and the dicarboxylic acid component includes (B) at least one selected from the group consisting of an aromatic dicarboxylic acid, an alicyclic dicarboxylic acid and dialkyl ester derivatives thereof at a ratio that is equal to or greater than 76 mol % and equal to or less than 100 mol % relative to a gross amount of the dicarboxylic acid component, the production method comprising: a first step that heats the above mixture, which has a water content equal to or less than 30% by weight, at a temperature equal to or higher than 200° C. under a pressure of 1.8 to 3.5 MPa to perform polycondensation with distillation of water; a second step that releases pressure to an atmospheric pressure level, subsequent to the first step; and a third step that continues thermal polycondensation subsequent to the second step, so as to obtain the crystalline polyamide resin, the third step performing high-degree melt polymerization at a temperature that is equal to or higher than a melting point of the crystalline polyamide resin until a relative viscosity at 25° C. of a solution prepared by dissolving the obtained crystalline polyamide resin at a concentration of 0.01 mg/mL in 98% sulfuric acid reaches between 1.8 and 3.5.

Dependencies are inferred from the claim text.