index detector shodex ri se 61 a product trade name of showa denko co ltd into a glass made reaction vessel equipped with a thermometer stirrer distilling receiver and reflux condenser were placed and dissolved 45 6 parts of dimethylformamide 33 1 parts of polyacrylic acid which contains an ingredient of molecular weight 300 to 2 500 in 36 by weight and an ingredient having a molecular weight of from over 2 500 to 5 000 or less in 28 by weight that in turn contains an ingredient of molecular weight 300 to 5 000 in 64 by weight and to the obtained mixture solution were added with stirring 1 part of ethylene glycol and 0 37 parts of 95 sulfuric acid and the thus obtained mixture was heated up to 150 u00b0 c eliminating distilled water from the water measuring tube the reaction mixture was still maintained for 5 hours to complete reaction and then cooled to ordinary temperature diluted with 200 parts of water and completely neutralized with a 10 aqueous sodium hydroxide solution after neutralization the reaction mixture was separated to two phases the water phase was taken out and added into a large amount of methanol a precipitate thus formed was taken by filtration and dried at 60 u00b0 c under a reduced.