Adhesive hot-melt formulations with a main polymeric component, of at least one isotactic metallocene butene-1 polymer composition, that has a low viscosity, and that has a bimodal composition, directly obtained during polymerization, in two consecutive and separate reaction steps.Moreover, said hot-melts include less than 5% by weight of at least one viscosity modifier that is not solid at room temperature. Such unusually low level of said additives, surprisingly allows to attain substantially improved levels both of high adhesiveness and cohesion.The adhesive hot-melt formulations include less than 5% by weight of a polyethylene wax or of a blend of polyethylene waxes, that characterized by a highly linear/non-branched structure and by an exceptionally low Polydispersity Index. The presence of such peculiar polyethylene waxes, that are partially incompatible with the butene-1 polymer composition, allows to use the disclosed hot-melt formulations even in the presence of fibrous or perforated substrates.
