The acrylic-type ester employed as a comonomer has the general formula ##STR2## where R1 is hydrogen or alkyl group such as lower alkyl, methyl, ethyl, propyl, butyl, etc.; R is the moiety derived from an alcohol ROH where R is radical having from about 1 to 20 carbons or more, such as from about 2 to 20 carbons, for example from about 2 to 18 carbons but preferably from about 6 to 14 carbons.