To obtain a one-package water-based coating composition being capable of long-term storage, exhibiting very quick driability and good adhesion by adding a hydrazino-containing water-soluble compound to a dispersion obtained by polymerizing an ethylenically unsaturated monomer mixture containing a carbonyl-containing monomer, a double-bond-containing silane compound, or the like, under conditions in which the pH of the components added dropwise before the start of polymerization is specified.
In the radical polymerization of a mixture essentially consisting of a monomer mixture comprising 0.1-20 wt.% carbonyl-containing monomer, 0.1-20 wt.% compounds of formulae I and II, 0.1-10 wt.% radically polymerizable carboxyl-containing monomer, and 50-99.7 wt.% other monomers, an emulsifier, a polymerization initiator, and water, the polymerization is carried out under conditions in which a volatile base is present in the system, and the pH of the components added dropwise before polymerization is 6.0 or above, and a water-soluble compound having at least two hydrazino groups is added to the obtained copolymer dispersion in a ratio of the hydrazino groups to the carbonyl groups of (0.1-3)/1 by mole.
SAKAI YOSHIYUKI
HASHIMOTO TOMIO
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