| abstract |
A polyamide resin having a low yellowness and excellent thermal stability can be produced from a polyamide oligomer having a predetermined molecular weight and moisture content without causing any trouble in the process. A polyamide resin having a relative viscosity of 1.1 to 1.3 and a moisture content of 3% by mass or less is polycondensed by melt-kneading inside a cylinder S of an extruder to produce a polyamide resin. To do. The extruder has open vents OV1, OV2 and vacuum vents V1, V2. An open vent OV1 is provided in the vicinity of the supply port A3 such as the upper portion of the supply port A3, and a step-down element Y is provided on the upstream side of the positions of the vacuum vents V1 and V2. Further, the open vent OV2 is provided in the upstream area OA and is in a pressurized state. [Selection] Figure 1 |