A multi-layer article is disclosed. The article contains a base layer that contains at least one thermoplastic resin and a second layer containing a thermoplastic (co)polyformal superimposed over the base layer. The (co)polyformal conforms to formulae (1a) or (1b), ##STR00001## in which O-D-O and O-E-O independently denote a diphenolate group, -D- and -E- independently denote an aromatic group having 6 to 40 carbon atoms, k is a whole number from 1 to 1500, o stands for numbers from 1 to 1500, and m is z/o and n is (o-z)/o wherein z is 0 to o.