US 10,394,127 B2  38  37  -continued  -continued  LCl-7  LCl-15  LCl-16  LCl-17  LCl-8 10  LCl-9  LCl-10 25  LCl-11  LCl-12  LCl-13  LCl-14  Specific examples of the repeating unit having a lactone  structure in the resin (A) are shown below, but the present  invention is not limited thereto. In the formulae, Rx repre› sents H, CH$_{3}$ ,  CH$_{2}$OH, or CF$_{3}$ .  The resin (A) may or may not contain a repeating unit  having a lactone structure, but in a case where the resin (A)  contains the repeating unit having a lactone structure, the  content of the repeating unit in the resin (A) is preferably in  the range of 1 % to 70% by mole, more preferably in the  range of3% to 50% by mole, and still more preferably in the  range of 5% to 45% by mole, with respect to the total content  of all repeating units.  The repeating unit having a lactone structure usually has  an optical isomer, and any optical isomer may be used.  Further, one kind of optical isomer may be used singly or a  plurality of optical isomers may be mixed and used. In a case  of mainly using one kind of optical isomer, the optical purity  ( ee) thereof is preferably 90% or more, and more preferably  95% or more.  The lactone structural moiety may or may not have a  substituent (Rb$_{2}$ ).  Preferred examples of the substituent  (Rb$_{2}$ )  include an alkyl group having 1 to 8 carbon atoms, a  cycloalkyl group having 4 to 7 carbon atoms, an alkoxy  group having 1 to 8 carbon atoms, an alkoxycarbonyl group  having 2 to 8 carbon atoms, a carboxyl group, a halogen  atom, a hydroxyl group, a cyano group, and an acid› decomposable group. Among these, an alkyl group having 1  to 4 carbon atoms, a cyano group, and an acid-decomposable  group are more preferable. n$_{2 }$ represents an integer of0 to 4.  In a case where n$_{2 }$ is  2  or more, the substituents (Rb$_{2}$ )  which  are present in plural numbers may be the same as or different  from each other, and further, the substituents (Rb$_{2}$ )  which  are present in plural numbers may be bonded to each other  to form  a  ring.  0  Rx  0 