Example 3
37 parts of ethylene glycol monobutyl ether was placed in a reactor equipped with a thermometer, a thermostat, a stirrer, a reflux condenser, and a dropping funnel; and heated with stirring to maintain the reaction mixture at 110° C. A mixture of 10 parts of styrene, 35 parts of methyl methacrylate, 20 parts of 2-ethylhexyl methacrylate, 5 parts of N,N-dimethylaminoethyl methacrylate, 10 parts of 2-hydroxyethyl methacrylate, 20 parts of methoxy polyethylene glycol monomethacrylate (molecular weight: about 2080), 1 part of azobisisobutyronitrile, and 5 parts of isobutyl alcohol was added dropwise thereto over 3 hours. After the completion of dropwise addition, the mixture was aged at 110° C. for 30 minutes. Subsequently, an additional catalyst mixture of 20 parts of ethylene glycol monobutyl ether and 0.5 parts of azobisisobutyronitrile was added dropwise over 1 hour. After aging at 110° C. for 1 hour, the mixture was cooled, thereby obtaining an acrylic resin (R-3) solution with a solids content of 50%. The obtained resin had a weight average molecular weight of 20000.
