US 9,052,592 B2  93  94  -continued  -continued  (r-cr-1-7)  *  ?)  )-a  0  (r-cr-2-1)  ~  oyo  0  (r-cr-2-2)  •~  R  oyo  0  (r-cr-2-3)  ~  oyo  0  (r-cr-2-4)  ~  oyo  0  (r-cr-3-1)  oyo  0  (r-cr-3-5)  oyo  0  (r-cr-3-4)  oyo  0  (r-cr-3-3)  oyo  0  (r-cr-3-2)  oyo  0  Of the foregoing, the constituent unit (a2) is preferably a  constituent unit derived from an acrylic ester in which the  hydrogen atom bonded to the carbon atom at the a-position  may be substituted with a substituent.  Such a constituent unit (a2) is preferably a constituent unit  represented by the following general formula (a2-1). 