Ethylene acid copolymers, ionomers, and their use in their packaging films and injection molded articles

There are novel ethylene-acid copolymers, their ionomers, and their use in various articles, including packaging films and injection molded articles provided. consisting of ethylene-acid copolymers copolymerized units of ethylene, from about 10 to about 30 wt .-% copolymerized units of a first α, β-unsaturated carboxylic acid having 3 to 10 carbon atoms, and from about 5 to about 15 copolymerized wt .-% units of a derivative of a second α, β-unsaturated carboxylic acid having 3 to 10 carbon atoms. Preferred derivatives include esters and, in particular alkyl ester. These ethylene-acid copolymers and ionomers have improved optical properties compared to conventional ethylene-acrylic or methacrylic acid copolymers and their ionomers.