Process for producing water-base resin dispersion

A process for producing a water-base resin dispersion having an average resin particle diameter of 25 to 100 nm by emulsion polymerization of a radical-polymerizable ethylenically unsaturated monomer in the presence of a reactive emulsifier in an amount of 2 to 10 parts by weight per 100 parts by weight of the radical-polymerizable ethylenically unsaturated monomer, the process comprising dropwise adding a mixture containing 30 to 100% by weight the total weight of said radical-polymerizable ethylenically unsaturated monomer, 20 to 90% by weight of the total weight of said reactive emulsifier and water to a reactor containing a transition metal in an amount of 10.sup.-7 to 10.sup.-5 moles per liter of the water placed in the reactor, 0 to 70% by weight of said radical-polymerizable ethylenically unsaturated monomer and 10 to 80% by weight of said reactive emulsifier and radical-polymerizing the radical-polymerizable ethylenically unsaturated monomer in the presence of an organic polymerization initiator,

• wherein:
• the radical-polymerizable ethylenically unsaturated monomer is at least one monomer selected from the group consisting of alkyl acrylates, alkyl methacrylates, styrene-containing monomers, vinyl carboxylates, acrylonitrile and methacrylonitrile, and
• the reactive emulsifier is at least one emulsifier selected from the group consisting of sulfosuccinic acid ester emulsifiers of the following formulae (1) or (2) and alkylphenol ether type emulsifiers of the following formula (3), ##STR7## wherein R.sup.1 is an alkyl group having 12 to 30 carbon atoms, and M.sup.1 is Na, NH.sub.4 or K, ##STR8## wherein R.sup.1 and M.sup.1 are as defined in the formula (1) ##STR9## wherein R.sup.2 is an alkyl group having 8 to 12 carbon atoms, X is H or SO.sub.3 M.sub.2 in which M.sub.2 is Na, NH.sub.4 or K, and n is a number of from 50 to 120.