US 9,557,643 B2  274  273  Furthermore, a solution obtained by adding and dissolving  polymerization initiator V-601 (produced by Waka Pure  Chemical Industries, Ltd.) in a ratio of 6 mo!  % based on the  monomers was added dropwise to (Solvent 1) over 6 hours.  After the completion of dropwise addition, the solution was  further reacted at 80°  C. for 2 hours. The reaction solution  was allowed to cool and then added dropwise to a mixed  solution of 1,400 ml ofhexane/600 ml of ethyl acetate, and  the precipitated powder was collected by filtration and dried  to obtain 37 g of Resin (Al-1-1). The weight average  molecular weight (Mw: in terms of polystyrene) as deter› mined by GPC of Resin (Al-1-1) obtained was 10,000, and  the polydispersity (Mw/Mn) was 1.60.  compositional ratio of respective repeating units m the  polymer structure is shown by molar ratio.  (Al-1-1)  a/b/c/d  ~  40/10/40/10  MW~ 10000, Mw/Mn  ~  1.60  a/b/c/d  ~  40/10/46/4  MW~ 11000, Mw/Mn  ~  1.60  (Al-1-2)  0  a/b/c/d  ~  40/10/47/3  MW~ 11000, Mw/Mn  ~  1.85  (Al-2)  Resins (Al-1-2) and (Al-2) to (Al-15) were synthesized  by the same method. The polymer structure, weight average 65  molecular weight (Mw) and polydispersity (Mw/Mn) of  each of resins synthesized are shown below. Also, the  M-1  X  #;<N  0  M-2  X  OH  OH  M-3  X  M-4  OH 