PURPOSE: To obtain the subject coating material consisting of a specific polyester resin, a block polyisocyanate and water as major components, excellent in chipping resistances and useful for multiple layered coated films.
CONSTITUTION: This aqueous coating material for middle coating comprises (A) a polyester resin, (B) one or more kinds of blocked polyisocyanates selected from the polymer of an aliphatic polyisocyanate and the adduct to the polymer and the adduct to an aliphatic polyisocyanate and (C) water, and preferably having 0.5-1.5mol, more preferably 0.8-1.2mol blocked polyisocyanate group of the component B based on the 1mol hydroxy group in the component A. It is preferable that the component A is one or more kinds of compounds selected from a lactone modified polyester resin and a polyether-polyester resin and has approximately 10000-20000 weight averaged molecular weight, approximately 80-150 hydroxyl group value and approximately 20-40 acid value. Also, the component B does not preferably contain a cycloaliphatic or an aromatic polyisocyanate.
SHIMAKAWA MOTOMI
ISAKA HISASHI
MATSUMOTO NAOJI
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