PURPOSE: To obtain a water-base coating composition which can give a transparent gas-barrier layer with a reduced humidity dependence by incorporating a specified amount of an unsaturated vinylidene monomer into an aqueous solution containing a PVA polymer and effecting polymerization at a specified temperature in the presence of a specified free-radical initiator.
CONSTITUTION: 100 pts.wt. aqueous solution consisting of 0.5-50 pts.wt. vinyl alcohol polymer and water is mixed by stirring with 0.001-10 pts.wt. unsaturated vinylidene monomer and, if necessary, less than 5 pts.wt. other polymerizable unsaturated monomer, and polymerization is effected in the presence of a redox free-radical initiator. The initiator is incorporated in an amount sufficient to provide a weight ratio thereof to the total of the unsaturated monomers of (0.001 to 0.1):1, and the polymerization temperature is controlled to be in the range of 0-50°C. The obtained coating composition contains 0.5-50wt.% compound resin composition which has a weight ratio of the vinylidene component to the vinyl alcohol component of (0.01 to 0.15):1 and at least a part of which comprises a graft and/or block copolymer.
MAEDA KOZO
YAMADA KOJI
KUZE KATSURO
