The present invention relates to an integrally blow-moulded bag-in-container (2) and preform(1, 1) for blow-moulding the bag-in-container. An inner layer (11) and an outer layer (12) are used, wherein the preform forms a two-layer container upon blow-moulding, and wherein the obtained inner layer of said container releases from the thus obtained outer layer upon introduction of a gas at a point of interface (14) between the two layers. At least one of the inner and outer layers includes at least one additive allowing both inner and outer layers to reach their respective blow-moulding temperatures substantially simultaneously.

A dual container, including a container body and a mouth portion attachment. The container body includes an inner bag and an outer shell that is disposed to cover the inner bag, and the inner bag is configured to be extractable from the container body, and the mouth portion attachment is attached to a mouth portion of the inner bag and is configured to be removable from the mouth portion.

A method of manufacturing a cartridge consisting of a stiff outer container and a deformable inner bag, where an extruder coextrudes a preform, and the method includes (a) cutting away a pinch seam from the cartridge to a residual width of 0.6 to 0.15 mm, (b) laterally compressing the cartridge and at the same time, rotating the cartridge about its longitudinal axis until the pinch seam bursts open, whereby the welded base seam of the inner bag remains adhered on one side of the burst open pinch seam and the base region of the inner bag on the other side of the inner wall of the outer container is pre-delaminated, (c) producing a reduced pressure in the inner bag so that the inner bag collapses at the pre-delaminated side, and (d) subsequently completely applying the inner bag to the inner wall of the outer container by an increased pressure.