| 摘要 |
<p>PROBLEM TO BE SOLVED: To obtain a composite resin improved in properties such as weather resistance, alkali resistance and heat resistance without detriment to adhesion to substrates, abrasion resistance and solvent resistance by reacting a polyol with an organic polyisocyanate in an active hydrogen-free unsaturated monomer, chain-extending the product, dispersing the chain-extended product in water and subjecting the dispersion to radical polymerization. SOLUTION: A polyol (e.g. ethylene glycol or polyether polyol) is dissolved in an active-hydrogen-free unsaturated monomer (methyl acrylate) and reacted with an organic polyisocyanate to obtain an isocyanate-terminated urethane prepolymer having a number-average molecular weight of 20,000 or below. This is chain-extended with a low-molecular-weight polyol or a low-molecular- weight polyamine in an organic solvent (e.g. isopropanol) to obtain a polyurethane solution. This is dispersed in water, and the dispersion is subjected to radical polymerization at a reaction temperature of 40-100 deg.C by a known method.</p> |
