Jul. 18, 2019  14  US 2019/0219920 Al  in the case where Ra’ 4  to Ra’ 6  are not mutually bonded and  independently represent a hydrocarbon group, the group  represented by general formula (al-r2-2) shown below can  be mentioned.  In the formulae, Ra’ $^{10 }$represents an alkyl group of  1  to  10  carbon atoms; Ra’ 11  is a group which forms an aliphatic  cyclic group together with a carbon atom having Ra’ 10  bonded thereto; and Ra,1 2  to Ra,1 4  each independently rep› resents a hydrocarbon group.  [0203]  In the formula (al-r2-1), as the alkyl group of  1  to  10  carbon atoms for Ra’ 10 ,  the same groups as described  above for the linear or branched alkyl group for Ra’ 3  in the  formula (al-r-1) are preferable. In the formula (al-r2-1), as  the aliphatic cyclic group which is formed by Ra’$^{11 }$together  with the carbon atom bonded to Ra’ 10 ,  the same groups as  those described above for the monocyclic or polycyclic  aliphatic hydrocarbon group for Ra’ $^{3 }$in the formula (al-r-1)  are preferable.  [0204]  In the formula (al-r2-2), it is preferable that Ra’ 12  and Ra,1 4  each independently represents an alkyl group or  1  to  10  carbon atoms, and it is more preferable that the alkyl  group is the same group as the described above for the linear  or branched alkyl group for Ra’ $^{3 }$in the formula (al-r-1 ), it is  still more preferable that the alkyl group is a linear alkyl  group of  1  to 5 carbon atoms, and it is particularly preferable  that the alkyl group is a methyl group or an ethyl group.  [0205]  In the formula (al-r2-2), it is preferable that Ra’ 13  is the same group as described above for the linear or  branched alkyl group or monocyclic or polycyclic alicyclic  hydrocarbon group for Ra’ 3  in the formula (al-r-1). Among  these examples, monocyclic or polycyclic aliphatic hydro› carbon group for Ra’ 3  are more preferable.  [0206]  Specific examples of the group represented by the  aforementioned formula (al-r2-1) are shown below.  * rep› resents a valence bond (the same applies throughout the  present specification).  -continued  [Chemical Formula 14]  [Chemical Formula 15]  (al-r2-1)  (al-r2-2)  (r-pr-m2)  *  (r-pr-m3)  (r-pr-m4)  *  (r-pr-m5)  (r-pr-m6)  (r-pr-m7)  (r-pr-mS)  (r-pr-m9)  [3  (r-pr-mlO)  (r-pr-mll)  *  (r-pr-ml)  * 