Composition polyester and extrusion coating process.

A method of coating a metal substrate comprising: (a) heating the metal substrate to a temperature of about 120 to about 250 ° C to provide a preheated metal substrate; (B) heating a composition of solid thermoplastic coating to a temperature sufficient to melt the coating composition and provide a molten coating composition, said coating composition comprising: (i) from about 50% to about 100%, about the total weight of the composition, of a polyester blend comprising (a) a first polyester and (B) a second polyester, wherein the Tg of the first polyester is at least about 20 higher than the Tg of the second polyester wherein the first polyester has a weight range of about 9 to 1 to about 1 to 3. (ii) from 0% to about 25%, of the total weight of the composition, of selected modifier unaresina from the group consisting of an epoxy or phenoxy resin having an epoxy equivalent weight of about 500 to about 15,000, an acrylic resin having a weight mo lecular weight average of about 15,000 to about 100,000, a polyolefin resin having a weight average molecular weight of about 15,000 to about 1,000,000, and mixtures thereof; (Iii) 0% to about 50%, of the total weight of the composcion, an inorganic filler agent, and; (Iv) 0% to about 4%, of the total weight of the composition, of a flow control agent. (C) extruding the coating composition cast on a metal substrate surface preheated to provide a layer of the coating composition melt with a thickness of about one to about 40 microns on the preheated metal substrate and a coated metal substrate is provided; and (d) cooling the coated metal substrate; Y