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 invention is simple in process and short in production period; and the content of oligomers in the semi-aromatic
polyamide product is remarkably reduced and is lower than 0.85%, the molecular
weight distribution is narrow, no
pollution is caused to a mold during molding
processing, and the semi-aromatic polyamide product can be widely applied to the fields of
electronics, electrics, automobiles and the like.