New bags for packaging flowable materials in bags.

The invention relates to a bag polymeric film ECOLOGICAL (10, 20) made of a polyethylene film for packaging of fluid materials, for example milk structure. This film can be a monolayer or multilayer structure (30), for example an extruded film BICAPA O TRICAPA (30) containing at least one layer (31) of a blend of ultra low density polyethylene and polyethylene low density RESISTANT TO HIGH PRESSURE AS SEALED WITH HIGH LAYER melt strength. Is also described a method of manufacture of said bag (10, 20) for packaging MATERIALS fluid using a structure as described above.