Patent ID: 7485696
Filing Date: 2009-02-03
Classification: C08G

Abstract:
1. A method for producing an oxytetramethylene glycol copolymer having the following characteristics (1) to (4): (1) a number average molecular weight Mn of from 800 to 5000; (2) a characteristic wherein the weight average molecular weight Mw and the number average molecular weight Mn satisfy either the following (i) or the following (ii): wherein Mw and Mn satisfy the relationship defined by the following formula (I): (3) a neopentyl glycol copolymerization whole ratio N (4) a characteristic wherein the number average molecular weight Mn, the neopentyl glycol copolymerization whole ratio N wherein N wherein said high molecular weight-side 15 wt % fraction is a fraction of said oxytetramethylene glycol copolymer, which fraction corresponds to the area of a part of a whole peak representing the molecular weight distribution over the whole range of from a low molecular weight to a high molecular weight in a gel permeation chromatogram of said oxytetramethylene glycol copolymer, wherein said part is taken on the side of the high molecular weight including the maximum molecular weight in said whole peak and wherein the area of said part of the whole peak is 15%, based on the area of said whole peak; said method comprising: subjecting tetrahydrofuran and neopentyl glycol to a copolymerization reaction in the presence of a heteropolyacid catalyst to form a reaction system, said copolymerization reaction being continuously performed in the presence of water in a continuous copolymerization reactor while continuously feeding tetrahydrofuran and neopentyl glycol to the continuous copolymerization reactor and while continuously removing water which is by-produced in the copolymerization reaction so that the amount of water in the reaction system is adjusted to a level wherein a two-phase reaction system is formed which comprises an organic phase comprising a solution of neopentyl glycol in tetrahydrofuran and having a neopentyl glycol concentration of from 0.1 to 1.0 weight %, based on the weight of the organic phase, and a tetrahydrofuran/aqueous heteropolyacid phase comprising a solution of an aqueous heteropolyacid catalyst in tetrahydrofuran and having a specific gravity of from 1.8 to 2.3, the by-produced water being continuously removed by azeotropically distilling off water and tetrahydrofuran from the reaction system and returning tetrahydrofuran to the reaction system in an amount which is equivalent to the amount of tetrahydrofuran removed by the azeotropic distillation, wherein said continuous copolymerization reaction is continued while maintaining said two-phase reaction system, to thereby form a copolymerization reaction mixture comprising a reaction-formed organic phase containing a oxytetramethylene glycol copolymer having a number average molecular weight of from 800 to 5000 and a reaction-formed tetrahydrofuran/aqueous heteropolyacid phase; separating said reaction-formed organic phase containing said oxytetramethylene glycol copolymer from said copolymerization reaction mixture; and separating and purifying said oxytetramethylene glycol copolymer from said reaction-formed organic phase.