Process for synthesizing low-chlorine film polyphenylene sulfide resin

The invention discloses a process for synthesizing a low-chlorine film polyphenylene sulfide resin. In the process, sodium sulfide and santochlor are taken as raw materials, N-methyl-2pyrrolidone (NMP) is used as a solvent, and the ratio of sodium sulfide to santochlor to NMP to NaOH to sodium bicarbonate to NaHS is 1:1:3.9:(0.2-0.3):(0.2-0.3):0.05. The process comprises the following steps: in the dehydration period of the sodium sulfide, under the condition of relative low temperature of 120-130 DEG C and pressure of -0.3MPa and the protection of nitrogen, carrying out vacuum dehydration on the sodium sulfide to obtain the sodium sulfide solution of which the moisture content is 1.0-1.2mol/mol Na2S; adding NaOH, NMP and P-DCB at a corresponding molar ratio; and finally reducing the temperature at a temperature-reducing speed of 30 DEG C/min, and washing and drying to obtain the low-chlorine film polyphenylene sulfide resin required in the invention. The product in the invention has low total content of Halo