The invention discloses semi-aromatic
polyamide and a preparation method thereof. The preparation method comprises the following steps that (a),
dicarboxylic acid and
diamine are subjected to a
neutralization reaction with water as the
solvent, and a semi-aromatic
polyamide salt solution is formed; (b), the semi-aromatic
polyamide salt solution obtained in the step (a) is further subjected to warming, polycondensation of the solution is promoted by continuous drainage, and after prepolymerization of the solution, semi-aromatic polyamide
prepolymer is obtained; (c), the semi-aromatic polyamide
prepolymer obtained in the step (b) is subjected to a
viscosity-enhancing reaction, and the semi-aromatic polyamide is obtained. According to the preparation method, the aggregate-level
dicarboxylic acid and
diamine are adopted, so that the operational process is simplified; a
diamine online separation
recovery device is used for conducting separation and recycling on the diamine in a prepolymerization process, so that the volatilization loss of the diamine along with
water vapor is effectively reduced, and
pollution generation is avoided; the
molar ratio of the diamine to the
dicarboxylic acid in the prepolymerization process is kept, so that the yield coefficient is increased, and the product with stable quality is obtained.