4-Acetoxystyrene (29.19 g) (0.18 mol), 12.80 g (0.09 mol) of t-butyl methacrylate, 4.66 g (0.03 mol) of 4-vinylquinoline, and 3.45 g (0.015 mol) of polymerization initiator V-601 (manufactured by Wako Pure Chemical Industries) are dissolved in 148.99 g of cyclohexanone. Cyclohexanone (37.25 g) is put in a reaction vessel and the above solution is dropped into the reaction system at 80° C. over 6 hours under nitrogen gas atmosphere. After dropping, the reaction solution is stirred while heating for 2 hours, and then allowed to cool to room temperature. The solution is dropped into 2.5 liters of hexane to thereby precipitate and filter the polymer. The solid filtered is roughly washed with 500 ml of hexane and dried under reduced pressure to obtain 41.30 g of t-butyl methacrylate/4-vinylquinoline/4-acetoxystyrene copolymer.
