Aqueous dispersion of cationic fine grain gel and process for preparing the same

A process for preparing an aqueous dispersion of a cationic fine grain gel, characterized by microemulsion polymerizing an unsaturated monomer M under the presence of a polymer P which is a polymer containing 30 to 92.5% by mole of a nonionic structure unit (a) and 70 to 7.5% by mole of a quaternary ammonium group-containing structure unit (b), and in which the content of a structure unit (b.sub.1) having a quaternary ammonium group and a polymerizable double bond, represented by the formula (I):

• ##STR4## wherein R.sub.1 is hydrogen atom or methyl group, each of R.sub.2 and R.sub.3 is independently an alkyl group having 1 to 4 carbon atoms, A is --O-- or --NH--, E is an alkylene group having 2 to 4 carbon atoms or a hydroxy-substituted alkylene group, Y is an aliphatic hydrocarbon residual group substituted with a hydroxy group and having one allyloxy group or one (meth)acryloyl group, or is a vinyl aromatic hydrocarbon residual group, and X.sup.- is a halogen anion, a sulfate anion, an alkylsulfate anion, an acetate anion, (meth)acrylic acid anion or OH-,
• is 1 to 100% by mole based on 100% by mole of said structure unit (b), and said content is at least 1% by mole based on 100% by mole of the total amount of said structure unit (a) and said structure unit (b).