Method for producing polyphenylene ether
Disclosed is a method for producing a polyphenylene ether, which comprises a step of preparing a polymerization solution composed of 10-25 parts by mass of a phenolic compound (M) and 75-90 parts by mass of an aromatic solvent (A) with the total of the compound and the solvent being 100 parts by mass, and 0.1-10 parts by mass of a catalyst (C) containing a metal salt; a step of performing an oxidative polymerization of the phenolic compound (M) by passing an oxygen-containing gas through the polymerization solution; a step of stopping the polymerization by mixing an aqueous chelating agent solution into the polymerization solution; a step of subjecting a diphenoquinone compound produced as a by-product to a quinone binding process or removal by reduction; and a step of obtaining a polyphenylene ether by separating the aqueous phase through liquid-liquid separation. In the method for producing a polyphenylene ether, 0.001-0.004 part by weight of an ion catalyst (D) is added into the polymerization solution before the liquid-liquid separation.
1. A method for producing a polyphenylene ether, comprising:
preparing a polymerization solution comprising 100 parts by mass in total of 10 to 25 parts by mass of a phenolic compound (M) and 75 to 90 parts by mass of an aromatic solvent (A), and 0.1 to 10 parts by mass of a catalyst (C) comprising a metal salt as a component;
passing an oxygen-containing gas through the polymerization solution to oxidatively polymerize the phenolic compound (M);
mixing a chelating agent aqueous solution with the polymerization solution to terminate the polymerization;
subjecting a diphenoquinone compound produced as a by-product to disposal by a quinone-coupling or to a reduction removal; and thereafter,
subjecting the polymerization solution to a liquid-liquid separation to separate a water phase to obtain the polyphenylene ether,
wherein 0.001 to 0.004 part by weight of an ion catalyst (D) is added to the polymerization solution before the liquid-liquid separation is carried out.
2. The method according to claim 1 , wherein the ion catalyst (D) is added to the polymerization solution immediately before the liquid-liquid separation is carried out.
3. The method according to claim 1 , wherein the ion catalyst (D) is added to the polymerization solution when the polymerization solution is prepared.
4. The method according to claim 1 , wherein the ion catalyst (D) is added in an amount of 0.001 to 0.003 part by mass.
5. The method according to claim 1 , wherein the ion catalyst (D) is a tetraalkylammonium salt compound represented by formula (4) shown below, or a polyethylene glycol group-containing alkylammonium salt compound represented by formula (5) shown below:
wherein R 1 , R 2 , R 3 and R 4 are each independently a straight chain or branched chain alkyl group having 1 to 22 carbon atoms; and X is a negative ion as a counterion;
wherein R 8 and R 9 denote a straight chain or branched chain alkyl group having 1 to 22 carbon atoms; R 10 is a group defined as R 8 , or a group represented by —(CH 2 CH 2 O) n —H (where n is an integer of 1 to 40); R 11 is a group represented by —(CH 2 CH 2 O) n —H (where n is an integer of 1 to 40); and X is a negative ion as a counterion.
6. The method according to claim 1 , wherein the ion catalyst (D) is trioctylmethylammonium chloride.
7. The method according to claim 1 , wherein a diphenoquinone compound produced as a by-product is subjected to disposal by a quinone-coupling after the chelating agent aqueous solution is mixed with the polymerization solution to terminate the polymerization.
8. The method according to claim 1 , wherein the oxygen-containing gas is an oxygen-containing gas having an oxygen concentration of 10 to 25% by volume.
9. The method according to claim 1 , further comprising using an oxygen-containing gas having an oxygen partial pressure of 0.0147 MPa or higher and 0.0883 MPa or lower, and controlling an absolute pressure of a reactor gas phase section to 0.098 MPa or higher and lower than 0.392 MPa.