PURPOSE: To obtain the title composition excellent in water resistance, processability and film strength, by mixing a specified modified epoxy resin composition with a water-based acrylic or polyester resin and a water-based amine/formaldehyde condensate.
CONSTITUTION: A hydroxylated epoxy resin (a) is obtained by effecting an addition reaction of an aromatic epoxy resin of an epoxy equivalent of 170W4000, such as bisphenol A glycidyl ether, with a mono- to poly-hydric aliphatic alcohol (e.g., ethylene glycol) in an amount at least twice as much as the epoxy groups so that at least 80mol% of the epoxy groups may be consumed. The resin (a) is reacted with a polybasic carboxylic acid (anhydride) (b) such as phthalic acid (anhydride) at a specified ratio and 120W200°C for 1W6hr to obtain a modified epoxy resin composition (A) which has an acid value of 20W300 and gives an aqueous solution or dispersion in the presence of a volatile base (e.g., NH3). 5W30% (in terms of solid matter, the same shall apply hereinbelow) is mixed with 5W45% water-based acrylic or polyester resin (B) and 10W50% water-based amine/formaldehyde condensate (e.g., alkyl- etherified malamine resin).
Nakamura, Tetsuhisa
Shiozawa, Kimihide
Ueda, Yukihiro
