PURPOSE: To obtain at a high production rate the titled polymer which has a desired degree of sulfonation and can give a separatory membrane having excellent membrane performances such as a long membrane life, by sulfonating a polyallyl ether polymer.
CONSTITUTION: For example, 4,4'-dichlorodiphenyl sulfone, 4,4'- dihydroxybenzophenone, etc., are condensed together with an alkali metal (bi)carbonate (e.g., K2CO3) in the presence of a sulfone or sulfoxide solvent (e.g., sulfolane) and, optionally, an organic solvent such as xylene to obtain a polyallyl ether polymer comprising 1mol% or above polymer (A) having repeating units of formula I (wherein X1W2 are CO or SO2 and n≥1) and, optionally, 99mol% or below repeating units of formula II. This polymer is dissolved in concentrated sulfuric acid and the solution is agitated at room temperature to sulfonate only component A and leave component B unsulfonated. In this way, the titled polymer having a desired degree of sulfonation and a logarithmic viscosity (in a solution of 0.5g of the polymer in 100ml of N-methylpyrrolidone at 30°C) of 0.2 or above is obtained.
ITO HIROYOSHI
YAMAMOTO SHOICHI
