US 2014/0030643 Al  27  Jan. 30,  2014  the number of aromatic rings introduced in the repeating unit  (A) is preferably up to 5, more preferably up to 3.  [0160]  Also, from the viewpoint of roughness perfor› mance, it is preferred for AR of each of the repeating units (A)  of general formula (BZ) to contain two or more aromatic  rings. More preferably, AR is a naphthyl group or a biphenyl  group. Generally, the number of aromatic rings introduced in  AR is preferably up to 5, more preferably up to 3.  [0161]  As mentioned above, Rn represents an alkyl group,  a cycloalkyl group or an aryl group.  [0152]  In general formula (BZ), AR represents an aryl  group. Rn represents an alkyl group, a cycloalkyl group or an  aryl group. Rn and AR may be bonded to each other to thereby  form a nonaromatic ring.  [0153]  R$_{1 }$ represents a hydrogen atom, an alkyl group, a  cycloalkyl group, a halogen atom, a cyano group or an alky› loxycarbonyl group.  [0162]  The alkyl group represented by Rn may be in the  form of a linear or branched chain. As a preferred alkyl group,  there can be mentioned an alkyl group having 1 to 20 carbon  atoms, such as a methy 1 group, an ethy 1 group, a propy 1 group,  an isopropyl group, an n-butyl group, an isobutyl group, a  t-butyl group, a pentyl group, a hexyl group, an octyl group or  a dodecyl group. The alkyl group represented by Rn more  preferably has 1 to 5 carbon atoms, further more preferably 1  to 3 carbon atoms.  [0154]  The aryl group represented by AR is preferably one  having 6 to 20 carbon atoms, such as a phenyl group, a  naphthyl group, an anthryl group or a fluorene group. An aryl  group having 6 to 15 carbon atoms is more preferred.  [0155]  When AR is a naphthyl group, an anthryl group or a  fluorene group, the position of bonding of AR to the carbon  atom to which Rn is bonded is not particularly limited. For  example, when AR is a naphthyl group, the carbon atom may  be bonded to whichever position, a-position or ~-position, of  the naphthyl group. When AR is an anthryl group, the carbon  atom may be bonded to any of the I-position, 2-position and  9-position of the anthryl group.  [0156]  One or more substituents may be introduced in each  of the aryl groups represented by AR. As particular examples  of such substituents, there can be mentioned a linear or  branched alkyl group having 1 to 20 carbon atoms, such as a  methyl group, an ethyl group, a propyl group, an isopropyl  group, an n-butyl group, an isobutyl group, at-butyl group, a  pentyl group, a hexyl group, an octyl group or a dodecyl  group; an alkoxy group containing any of these alkyl groups  as its part; a cycloalkyl group, such as a cyclopentyl group or  a cyclohexyl group; a cycloalkoxy group containing such a  cycloalkyl group as its part; a hydroxyl group; a halogen  atom; an aryl group; a cyano group; a nitro group; an acyl  group; an acyloxy group; an acylamino group; a sulfony› lamino group; an alkylthio group; an arylthio group; an  aralkylthio  group;  a  thiophenecarbonyloxy  group;  a  thiophenemethylcarbonyloxy group; and a heterocyclic resi› due, such as a pyrrolidone residue. Among these substituents,  a linear or branched alkyl group having 1 to 5 carbon atoms  and an alkoxy group containing the alkyl group as its part are  preferred. A paramethyl group and a paramethoxy group are  more preferred.  [0157]  When a plurality of substituents are introduced in  the aryl group represented by AR, at least two members of the  plurality of substituents may be bonded to each other to  thereby form a ring. The ring is preferably a 5- to 8-membered  one, more preferably a 5- or 6-membered one. Further, this  ring may be a heteroring containing a heteroatom, such as an  oxygen atom, a nitrogen atom or a sulfur atom, as a ring  member.  [0158]  A substituent may further be introduced in this ring.  The substituent is the same as the further substituent men› tioned below as being introducible in Rn.  [0159]  From the viewpoint of roughness performance, it is  preferred for each of the repeating units (A) of general for› mula (BZ) to contain two or more aromatic rings. Generally,  [0163]  As the cycloalkyl group represented by Rn, there  can be mentioned, for example, one having 3 to 15 carbon  atoms, such as a cyclopentyl group or a cyclohexyl group.  [0164]  The aryl group represented by Rn is preferably, for  example, one having 6 to 14 carbon atoms, such as a phenyl  group, a xylyl group, a tolyl group, a cumenyl group, a naph› thyl group or an anthryl group.  [0165]  Substituents may further be introduced in the alkyl  group, cycloalkyl group and aryl group represented by Rn. As  such substituents, there can be mentioned, for example, an  alkoxy group, a hydroxyl group, a halogen atom, a nitro  group, an acyl group, an acyloxy group, an acylamino group,  a sulfonylamino group, a dialkylamino group, an alkylthio  group, an arylthio group, an aralkylthio group, a thiophen› ecarbonyloxy group, a thiophenemethylcarbonyloxy group,  and a heterocyclic residue, such as a pyrrolidone residue.  Among these substituents, an alkoxy group, a hydroxyl  group, a halogen atom, a nitro group, an acyl group, an acy› loxy group, an acylamino group and a sulfonylamino group  are especially preferred.  [0166]  As mentioned above, R$_{1 }$ represents a hydrogen  atom, an alkyl group, a cycloalkyl group, a halogen atom, a  cyano group or an alkyloxycarbonyl group.  [0167]  The alkyl group and cycloalkyl group represented  by R$_{1 }$ are, for example, the same as mentioned above in  connection with Rn. Substituents may be introduced in the  alkyl group and cycloalkyl group. The substituents are, for  example, the same as set forth above in connection with Rn.  [0168]  When R$_{1 }$ is a substituted alkyl group or cycloalkyl  group, it is especially preferred for R$_{1 }$ to be, for example, a  trifluoromethyl group, an alkyloxycarbonylmethyl group, an  alkylcarbonyloxymethyl group, a hydroxymethyl group or an  alkoxymethyl group.  [0169]  As the halogen atom represented by R$_{1}$, there can be  mentioned a fluorine atom, a chlorine atom, a bromine atom  or an iodine atom. A fluorine atom is most preferred.  [0170]  As the part of alkyl group contained in the alkyloxy› carbonyl group represented by Ri, there can be employed, for  example, any of the structures mentioned above as the alkyl  group represented by R$_{1}$.  [0171]  Preferably, Rn and AR are bonded to each other to  thereby form a nonaromatic ring. In particular, this can  enhance the roughness performance.  (BZ) 