Integrally blow-moulded bag-in-container having an inner layer and the outer layer made of the same material and preform for making it

An integrally blow-moulded dispensing bag-in-container having a body and a neck region, said bag-in-container comprising:

• a single layer inner bag which is collapsible and comprises an opening to an outer atmosphere defined by a lip;
• a single layer outer container;
• a vent disposed in the neck region;
• said vent between the inner bag and outer container, which opens to the atmosphere;
• and
• a source of pressurized gas releasably attached to the vent, wherein:
• the inner bag and the outer container comprise a same polymer,
• said inner bag is adjacent to and in direct contact with said outer container forming an interface therebetween,
• said inner bag and said outer container have said same polymer over substantially the entirety of the interface, and
• said dispensing bag-in-container being suitable for dispensing a liquid contained in an inner bag by pressurizing with the source of pressurized gas the interface between said inner bag and said outer container.