Continuous preparation method of semi-aromatic polyamide with low oligomer content and product thereof

The invention discloses a continuous preparation method of semi-aromatic polyamide with low oligomer content, which comprises the following steps: (a) by using water as a solvent and diamine and binary as initial feeding materials, adding a catalyst, pulping, heating to dissolve, neutralizing and salifying; (b) dehydrating and concentrating the salt solution obtained after neutralizing and salifying, detecting the content of diamine in the steam condensate, adjusting the molar ratio of amine to acid to be greater than 1.0, and then carrying out a prepolymerization reaction; and (c) sequentially carrying out flash evaporation spraying and circulating air drying containing extraction agent steam on the pre-polymerization reaction liquid, melting and tackifying by an extruder, and carrying out underwater pelletizing to obtain semi-aromatic polyamide particles with low oligomer content. The extractant vapor is selected from dichloromethane and/or trichloromethane vapor. The preparation method disclosed by the inv