Process for producing modified thermosetting polyphenylene ether resin

A process for producing modified thermosetting polyphenylene ether resin, without step of separating out polyphenylene ether resin into powder, comprising the following steps:

• a) dissolving a polyphenylene ether resin having a hydroxyl group in a good solvent selected from toluene solvent, xylene solvent, methyl isobutyl ketone (MIBK) solvent or butanone (MEK) solvent, heating to 65-85° C.;
• b) graft reaction for modification:
• b1) based on the total weight of the polyphenylene ether resin, adding 0.5%-5 wt % of a phase transfer catalyst to the good solvent after the resin is completely dissolved;
• b2) adding an aqueous solution containing alkali metal ion to allow the hydroxyl group of the polyphenylene ether resin to form terminal phenoxide;
• b3) dropwise adding a graft monomer in the presence of the phase transfer catalyst to perform graft modification reaction at 50-120° C.;
• and
• b4) setting the solution aside for reaction for 9-12 hours to obtain a modified thermosetting polyphenylene ether resin solution;
• c) performing water rinse to obtain a semi-finished product of a modified polyphenylene ether resin solution;
• d) performing extraction by adding a combination of an alcohol solvent and water as an extraction liquid into the modified polyphenylene ether resin solution, wherein alcohol solvent is selected from methanol, ethanol, propyl alcohol or butyl alcohol, to make sure to satisfy one of the following requirements:
• d1) a congruent point corresponding to those weight fractions of the good solvent, the alcohol solvent, and the water is located within a two phase liquid-liquid region of the good solvent—the alcohol solvent—water ternary phase diagram measured at 25-75° C. and 1-3 atmosphere;
• or,
• d2) a congruent point corresponding to those molar fractions of the good solvent, the alcohol solvent, and the water is located within a two phase liquid-liquid region of the good solvent—the alcohol solvent—water ternary phase diagram measured at 25-75° C. and 1-3 atmosphere;
• e) performing phase splitting to obtain the modified polyphenylene ether resin solution in a purified state;
• and
• f) drying the solution to obtain a final product of the modified polyphenylene ether resin having a purity of more than 99.4%.