Patent EA-003972-B1 (EA)
Title: Method for producing a container having a pressure compensation opening, and container produced according to said method
Inventor: KUEHN TORSTEN
IPC: B65D1/02
Filed: 2001-03-14
Abstract: 1. A process for production of a container (1) provided with a container opening (8), having a substantially rigid outer container (2) and an inner bag (3) disposed therein, which is in contact with the later container contents, these respectively comprising different thermoplastic plastics which are not bonded to each other, and a pressure equalisation opening (10), disposed in the outer container (2), which equalises a pressure difference between the outer container (2) and the inner bag (3), wherein a preliminary moulding, comprising two coaxial tubes which have a sufficient length for manufacture of the container, is first produced by coextrusion between the opened halves of the blow mould, the blow mould is closed and, with that an outwardly-projecting base seam (5) is formed, the excess material in the base area (4) of the container that is to be manufactured being squashed out in such a way that the material of the outer container (2) which is in contact in the area of the seam is welded together, the tube which forms the inner bag is clamped, axially fixed and welded between the wall sections of the outer container (2) and the inner bag (3) is subjected to pressure so that the walls of the preliminary moulding lie against the contours of the blow mould from inside, characterised in that on closing the blow mould and with the associated formation of the base seam (5), the seam of the inner bag (3) is at least partially fixed axially in the seam of the outer container and at least one pressure equalisation opening (10) is formed in that the base seam (5) is at least partially cut off after shaping and a radial force which acts in the direction of the base seam is exerted in the base area (4) in such a way that the base seam (5) breaks open, wherein the temperature of the pre-moulding is between 40 degree C and 70 degree C when the base seam is cut off and the outer container (2) is still plastically deformable to some degree, so that a permanent deformation results from the force which is not neutralised by elastic restoration. 2. A process according to claim 1, characterised in that when the base seam (5) is at least partially cut off and before the introduction of a radial force, an axial force which is exerted substantially parallel to the longitudinal axis of the container is briefly introduced in such a way that the base seam at least partially breaks open. 3. A process according to claim 2, characterised in that the axial force is introduced in the form of a blow. 4. A process according to one of the preceding claims, characterised in that the production of a container takes place without the formation of a shoulder seam in the form of a squeeze seam. 5. A process according to one of the preceding claims, characterised in that when the base seam (5) is at least partially broken open, the material which comprises the inner bag (3) remains stuck, on one side of the base seam (5), to the outer container (2) and the ends of the base seam (11), whereupon axial fixing is maintained. 6. A process according to one of the preceding claims, characterised in that the base seam (5) of the outer container (2) is only partially broken open and the seam of the inner bag (3) is fixed by the unbroken part of the base seam of the outer container (2). 7. A process according to one of the preceding claims, characterised in that cutting off the base seam (5) and application of the force which opens and permanently deforms the outer container (2) occur simultaneously in one work step. 8. A process according to claims 1 to 6, characterised in that cutting off the base seam (5) and application of the force which opens and permanently deforms the outer container (2) occur separately in separate work steps. 9. A process according to one of the preceding claims, characterised in that cutting off the base seam (5) and application of the force which opens and permanently deforms the outer container (2) take place on the plastic blowing machine. 10. A process according to claim 9, characterised in that the container (1) is still within the blow mould. 11. A process according to one of claims 1 to 8, characterised in that cutting off the base seam (5) and application of the force which opens and permanently deforms the outer container (2) take place on a machine which is attached to the plastic blowing machine. 12. A process according to one of the preceding claims, characterised in that the container (1) is configured in the shape of a bottle. 13. A process according to claim 12, characterised in that the inner bag (3) is also fixed in the area of the bottle neck (6) in addition to the fixing in the base area (4). 14. A process according to claim 13, characterised in that the inner bag (3) is at least partially clamped in the wall of the outer container (2) during forming of the bottle neck (6). 15. A process according to one of claims 12 to 14, characterised in that the bottle neck (6) is configured with a projection (7) on its face side extending outwards in the radial direction. 16. A process according to claim 15, characterised in that the inner bag (3) is connected with the outer container (2) by means of an upright or horizontal fold in the area of the projection (7). 17. A process according to claim 15, characterised in that the projection (7) is exclusively formed from material of the outer container (2). 18. A container (1) with a container opening (8) substantially comprising a rigid outer container (2) and an inner bag (3) disposed therein, which is in contact with the later container, preferably produced according to one of claims 1 to 17, characterised in that at least one pressure equalisation opening (10) is disposed in the base area (4), resulting from the base seam (5), which is formed during the moulding process, being at least partially cut off and on breaking open and deforming of the base seam (5) by the introduction of a radial force acting in the direction of the seam, the material which forms the inner bag (3) remaining stuck, on one side of the base seam (5), to the outer container (2) and the ends of the seam, whereupon the inner bag (3) is axially fixed and at the same time at least one pressure equalisation opening (10) is formed between the outside of the inner bag (3) and the inside of the outer container (2) which provides constant pressure equalisation. 19. A container according to claim 18, characterised in that the container (1) is bottle-shaped. 20. A container according to claim 19, characterised in that the inner bag (3) is also fixed in the area of the bottle neck (6) in addition to the fixing in the base area (4). 21. A container according to claim 20, characterised in that the inner bag (3) is at least partially clamped in the wall of the outer container (2) in the region of the bottle neck (6). 22. A container according to one of claims 19 to 21, characterised in that the bottle neck (6) is configured with a projection (7) on its face side extending outwards in the radial direction. 23. A container according to claim 22, characterised in that the connection of the inner bag (3) with the outer container (2) is at least partially in the area of the projection (7) and is an upright or horizontal fold. 24. A container according to claim 22, characterised in that the projection (7) is exclusively formed from material of the outer container (2).