-continued  -continued  68  67  US 9,052,590 B2  The repeating units of general formula (VI) below are also  preferred as the repeating unit (B2).  In general formula (VI), each ofR$_{6}$ i, R$_{62 }$and R$_{63 }$indepen› dently represents a hydrogen atom, an alkyl group, a monova› lent aliphatic hydrocarbon ring group, a halogen atom, a  cyano group or an alkoxycarbonyl group, provided that R$_{62 }$ may be bonded to Ar$_{6 }$ to thereby form a ring (preferably a 5- or 6-membered ring), which R$_{62 }$in this instance is an alkylene  group.  Ar$_{6 }$ represents an aromatic ring group.  Y, or each ofY s independently, represents a hydrogen atom  or a group that when acted on by an acid, is cleaved, provided  that at least one ofY sis a group that when acted on by an acid,  is cleaved.  In the formula, n is an integer of 1 to 4.  (V-96)  (VI)  (V-95)  (V-100)  --+~2-~+- ~  I  ~  o~o  (V-94)  (V-99)  1 H2  IH 3 \  C  -C-f- OAO  (V-98)  --+~2-~+- ¢  0  - o~o~  (V-93)  (V-92)  (V-97) 