. . . "lue of from 0.75 to 1.05, inclusive, b has a value of from to 0.25, inclusive, and the sum of a+b has a value of from 0.9 to 1.05, inclusive, 0 has a value of from 0.02 to 0.08, inclusive, d has a value of from 0.005 to 0.06, inclusive, and R' is an alkyl radical as previously defined." .