| 摘要 |
A powder coating composition which is suitable for precoated steel plates has excellent storage stability (e.g. blocking resistance) and provides a cured film having good weather resistance and a good balance of hardness and processability comprises; (I) 95 to 70 % by weight of a polyester resin having a glass transition temperature of 40 to 70 DEG C, prepared from (i) an acid component containing at least 80 mole % of an aromatic dicarboxylic acid with (ii) a polyol component which comprises (a)at least 50 mole % of neopentyl glycol, and (b) 1 to 10 % by weight of a diol selected from a linear chain C8-C16 alkylene diol, 2-methyl-1,8-octane diol and a mixture thereof, and (II) 5 to 30 % by weight of a curing agent. The acid component may further contain adipic, sebacic, succinic or trimellitic acid, and the polyol component may further contain other polyols, e.g. ethylene, propylene or trimethylene glycol, butane diol, neopentylglycol hydroxypivalate and cyclohexane dimethanol. The polyester preferably has an acid or hydroxyl value of 10 to 100 and a number average molecular weight of 2,000 to 10,000. The curing agent (II) is preferably an epoxy compound or a blocked isocyanate compound. The composition preferably contains 0.1 to 10% wt. of non-crosslinkable resin particles.
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