A process for producing a composite material includes the following steps: (a) melting at least one polyester having an inherent viscosity higher than or equal to 0.5 dl/g, preferably 0.6 dl/g to 1.2 dg/l; (b) cooling said polyester so as to obtain a polyester having a crystallinity lower than 30%, preferably 1% to 20%; and (c) mixing at least one layered clay material with the polyester obtained in step (b) so as to obtain the composite material. The composite material is particularly useful for manufacturing food or beverage containers, in particular bottles.