| 摘要 |
<p>PROBLEM TO BE SOLVED: To obtain the subject dispersion capable of producing a coating and a film having improved waterproofness and a lower glass transition temperature by using a polyol containing a specific polybutadiene resin. SOLUTION: This anionic aqueous polyurethane resin dispersion is obtained by using a polyol containing (A) a hydroxyl terminal group-containing polybutadiene resin, preferably and (B) a polyester polyol or a mixture thereof with a polyether polyol. Furthermore, the objective dispersion is preferably prepared by heating, e.g. the polyol and an aliphatic isocyanate such as isophorone diisocyanate with a mixture of an acid group-containing diol such as dimethylolpropionic acid dissolved in N-methylpyrrolidone together with a dibutyltin dilaurate catalyst (at about 60-80 deg.C for about 2-5hr), providing a prepolymer, then adding a tertiary amine such as triethylamine thereto, forming an anionic salt, subsequently cooling the resultant salt, adding a polyurethane prepolymer thereto under stirring and then extending the chain.</p> |
