. "Preferred examples of the alkyl groups are straight chain, branched or cyclic alkyl groups having from 1 to 20 carbon atoms each of which may have a substituent, and specific examples include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, a undecyl group, a dodecyl group, a tridecyl group," . . .