13  Jul. 18, 2019  US 2019/0219920 Al  (al-r-1)  [Chemical Formula 12]  [0186]  In the formula, Ra’$^{1 }$and Ra’$^{2 }$represents a hydrogen  atom or an alkyl group; and Ra’ 3  represents a hydrocarbon  group, provided that Ra’ 3  may be bonded to Rail or Ra’ 2 .  [0187]  In the formula (al-r-1), it is preferable that at least  one of Rail and Ra’ 2  represents a hydrogen atom, and it is  more preferable that both of Rail and Ra’ 2  represent a  hydrogen atom.  [0188]  In the case where Rail or Ra’ 2  is an alkyl group, as  the alkyl group, the same alkyl groups as those described  above the for the substituent which may be bonded to the  carbon atom on the a-position of the aforementioned a-sub› stituted acrylate ester can be mentioned, and an alkyl group  of  1  to 5 carbon atoms is preferable. Specific examples  include linear or branched alkyl groups. Specific examples  of the alkyl group include a methyl group, an ethyl group, a  propyl group, an isopropyl group, an n-butyl group, an  isobutyl group, a tert-butyl group, a pentyl group, an iso› pentyl group and a neopentyl group. Of these, a methyl  group or an ethyl group is preferable, and a methyl group is  particularly preferable.  [0189]  In formula (al-r-1), examples of the hydrocarbon  group for Ra’ 3  include a linear or branched alkyl group and  a cyclic hydrocarbon group.  [0190]  The linear alkyl group preferably has  1  to 5 carbon  atoms, more preferably  1  to  4,  and still more preferably  1  or  2. Specific examples include a methyl group, an ethyl group,  an n-propyl group, an n-butyl group and an n-pentyl group.  Among these, a methyl group, an ethyl group or an n-butyl  group is preferable, and a methyl group or an ethyl group is  more preferable.  [0191]  The branched alkyl group preferably has 3 to  10  carbon atoms, and more preferably 3 to 5. Specific examples  include an isopropyl group, an isobutyl group, a tert-butyl  group, an isopentyl group, a neopentyl group a 1,1-diethyl› propyl group and a 2,2-dimethylbutyl group. Among these,  an isopropyl group is preferable.  [0192]  In the case where Ra’ 3  represents a cyclic hydro› carbon group, the cyclic hydrocarbon group may be an  aliphatic hydrocarbon group or an aromatic hydrocarbon  group, and may be polycyclic or monocyclic.  [0193]  As the monocyclic aliphatic hydrocarbon group, a  group in which  1  hydrogen atom has been removed from a  monocycloalkane is preferable. The monocycloalkane pref› erably has 3 to 6 carbon atoms, and specific examples  thereof include cyclopentane and cyclohexane.  [0194]  As the polycyclic aliphatic hydrocarbon group, a  group in which  1  hydrogen atom has been removed from a  polycycloalkane is preferable, and the polycyclic group  preferably has 7 to 12 carbon atoms. Examples of the  polycycloalkane include adamantane, norbomane, isob› omane, tricyclodecane and tetracyclododecane.  [0195]  When the monovalent hydrocarbon group for Ra’ 3  is an aromatic hydrocarbon group, the aromatic hydrocarbon  group is a hydrocarbon group having at least one aromatic  ring.  [0196]  The aromatic ring is not particularly limited, as  long as it is a cyclic conjugated compound having (4n+2)it  electrons, and may be either monocyclic or polycyclic. The  aromatic ring preferably has 5 to 30 carbon atoms, more  preferably 5 to 20, still more preferably 6 to 15, and most  preferably 6 to 12. Examples of the aromatic ring include  aromatic hydrocarbon rings, such as benzene, naphthalene,  anthracene and phenanthrene; and aromatic hetero rings in  which part of the carbon atoms constituting the aforemen› tioned aromatic hydrocarbon rings has been substituted with  a hetero atom. Examples of the hetero atom within the  aromatic hetero rings include an oxygen atom, a sulfur atom  and a nitrogen atom. Specific examples of the aromatic  hetero ring include a pyridine ring and a thiophene ring.  [0197]  Specific examples of the aromatic hydrocarbon  group for Ra’ 3  include a group in which one hydrogen atom  has been removed from the aforementioned aromatic hydro› carbon ring or aromatic hetero ring (aryl group or heteroaryl  group); a group in which one hydrogen atom has been  removed from an aromatic compound having two or more  aromatic rings (biphenyl, fluorene or the like); and a group  in which one hydrogen atom of the aforementioned aromatic  hydrocarbon ring or aromatic hetero ring has been substi› tuted with an alkylene group (an arylalkyl group such as a  benzyl group, a phenethyl group, a 1-naphthylmethyl group,  a 2-naphthylmethyl group, a 1-naphthylethyl group, or a  2-naphthylethyl group). The alkylene group bonded to the  aforementioned aromatic hydrocarbon ring or the aromatic  hetero ring preferably has  1  to  4  carbon atoms, more  preferably  1  or 2 carbon atoms, and most preferably  1  carbon atom.  [0198]  In the case where Ra’ 3  is bonded to Rail or Ra’ 2  to  form a ring, the cyclic group is preferably a  4  to 7-membered  ring, and more preferably a  4  to 6-membered ring. Specific  examples of the cyclic group include tetrahydropyranyl  group and tetrahydrofuranyl group.  [0199]  -Tertiary Alkyl Ester-Type Acid Dissociable  Group  [0200]  Examples of the acid dissociable group for protect› ing the carboxy group as a polar group include the acid  dissociable group represented by general formula (al-r-2)  shown below. Among the acid dissociable groups repre› sented by general formula (al-r-2), for convenience, a group  which is constituted of alkyl groups is referred to as "tertiary  ester-type acid dissociable group".  [Chemical Formula 13]  In the formula, Ra’ 4  to Ra’$^{6 }$each independently represents a  hydrocarbon group, provided that Ra’s and Ra’ 6  may be  mutually bonded to form a ring.  [0202]  Ra’ 4  is preferably an alkyl group of  1  to 5 carbon  atoms. In the case where Ra’s and Ra’ $^{6 }$are mutually bonded  to form a ring, a group represented by general formula  (al-r2-1) shown below can be mentioned. On the other hand,  [0201]  As the hydrocarbon group for Ra’$^{4 }$to Ra’ 6 , the same  groups as those described above for Ra’ 3  can be mentioned.  (al-r-2) 