Example 9
Preparation of Polymer Solution A
After sufficient replacement with nitrogen gas in a flask equipped with a mechanical stirrer, a thermometer, a nitrogen gas introducing tube, a reflux tube, and a dripping funnel, 11.2 g of styrene, 2.8 g of acrylic acid, 12.0 g of lauryl methacrylate, 4.0 g of polyethylene glycol methacrylate, 4.0 g of styrene macromer, and 0.4 g of mercapto ethanol were mixed and heated to 65 degrees C.
Next, a liquid mixture of 100.8 g of styrene, 25.2 g of acrylic acid, 108.0 g of lauryl methacrylate, 36.0 g of polyethylene glycol methacrylate, 60.0 g of hydroxyethyl methacrylate, 36.0 g of styrene macromer, 3.6 g of mercapto ethanol, 2.4 g of azobisdimethyl valeronitrile, and 18 g of methylethyl ketone were dripped into the flask in two and a half hours. Subsequently, a liquid mixture of 0.8 g of azobismethyl valeronitrile and 18 g of methylethyl ketone was dripped into the flask in half an hour.
After one-hour aging at 65 degrees C., 0.8 g of azobismethyl valeronitrile was added and aged for another hour. After the reaction was complete, 364 g of methylethyl ketone was added to the flask to obtain 800 g of a polymer solution A having a concentration of 50 percent.
Preparation of Carbon Black Pigment Containing Polymer Particulate Dispersion
28 g of the polymer solution A, 42 g of C.I. carbon black (FW100, manufactured by Degussa AG), 13.6 g of 1 mol/l potassium hydroxide solution, 20 g of methylethyl ketone, and 13.6 g of deionized water were sufficiently stirred and thereafter mixed and kneaded with a roll mill. The thus-obtained paste was charged in 200 g of pure water. Subsequent to sufficient stirring, methylethyl ketone and water were distilled away by using an evaporator. To remove coarse particles, the liquid dispersion was filtered with a polyvinylidene fluoride membrane filter having an average opening diameter of 5.0 μm under pressure to obtain a carbon black pigment containing polymer particulate liquid dispersion having a pigment solid portion of 15% and a solid portion concentration of 20 percent. In addition, the volume average particle diameter (D50) of the polymer particulate in the liquid dispersion was 104 nm as measured by a particle size distribution measuring instrument (NANOTRAC UPA-EX150, manufactured by NIKKISO CO., LTD.).
