Patent ID: 6890996

Claim:
A process for preparing a branched polyvinyl imidazoline acid salt comprising: reacting a branched polyacrylonitrile with ethylenediamine in the presence of ammonium chloride and/or a hydrochloride of an amine, thereby obtaining a polymer; and contacting said polymer with an acid, thereby obtaining the branched polyvinyl imidazoline acid salt of formula (1) where X − denotes a chlorine anion, a sulfuric acid anion, a carbonic acid anion, a p-toluenesulfonic acid anion, a formic acid anion, an acetic acid anion, or a propionic acid anion, having a Huggins' constant k′, defined by the equation (1), η sp /C=k′[η] 2 C+[η] (1) where η sp denotes a specific viscosity, C denotes a concentration of a polymer, [η] denotes an intrinsic viscosity, and k′ denotes a Huggins' constant, of 0.2 to 1.2 and an intrinsic viscosity [η] of 2 to 20 based on measurements at 30° C. in a 0.1 mol/l aqueous solution of sodium chloride.