Process for the production of polyphenylene oxide

Claim 1

Process for the preparation of polyphenylene oxide by means of polymerization of 2,6-xylenol, with oxygen, or with a gas containing molecular oxygen, in the presence of a catalyst, within a liquid reaction medium in which the catalyst and the monomer are soluble, and polyphenylene oxide is insoluble or substantially insoluble, characterized in that: (a) to the bottom of a vertical and elongated reaction vessel monomer and an amount of the catalyst effective to polymerize the monomer is continuously fed dissolved in a liquid solvent, or in a mixture of liquid solvents, incapable of dissolving the polyphenylene oxide; (b) to the bottom of said reaction vessel a gaseous stream of oxygen, or of gas containing molecular oxygen is continuously fed in while maintaining the temperature below 35° C. by using a heat exchanger; (c) at the top of said reaction vessel, recovering a dispersion of solid polyphenylene oxide in the liquid reaction mixture; (d) recovering a portion of said dispersion, with the catalyst and the 2,6-xylenol,, and recycling such portion to the bottom of said reaction vessel while maintaining a weight ratio of the recycled portion to the fresh feed of at least 100/1; and (e) recovering the polyphenylene oxide from the remaining portion of said dispersion that is recovered from the top of the reaction vessel.