HK1055706B - Method for producing a container having a pressure compensation opening, and container produced according to said method - Google Patents

Description

Method for producing a container with pressure equalization openings and container produced thereby

Technical Field

The present invention relates to a method of manufacturing a container with a container opening. The container has a substantially rigid outer container and an inner bag disposed therein in contact with the contents of the container. The outer container and the inner bag comprise different thermoplastics which are not bonded to each other, and pressure equalizing holes which are provided in the outer container and equalize the pressure difference between the outer container and the inner bag. In this case, a preliminary moulded part comprising two coaxial tubes of sufficient length for the production of containers is produced by coextrusion between two open half-moulds of a forming die. The forming die is closed and has outwardly projecting base slots. Excess material on the base region of the container to be manufactured is squeezed out so that the outer container material in contact with the base seam region is welded together. Between the wall parts of the outer vessel, the tube forming the inner bag is clamped, axially fixed and welded. The inner bag is subjected to pressure so that the wall of the preliminary molding abuts from the inside against the contour of the forming die.

In addition, the invention relates to a container, preferably produced according to the method, with a container opening. The container basically comprises a rigid outer container and an inner bag placed therein in contact with the contents of the container.

Background

The process considered here is disclosed in WO 99/11451. The method is characterized in that the pressure equalization openings for smoothing the pressure difference between the outer container and the inner bag are preferably lenticular or oval openings made in the outer container, which are cut out in the wall of the outer container by means of a cutting tool after the actual forming process has been completed.

This means that the outer wall against which the very thin flexible inner bag rests must be completely cut over at least a very small area without damaging the inner bag. The machining of the outer container causes an inevitable contact between the cutting tool and the inner bag. It is therefore not possible to obtain at the same time the most important quality features of the method and of the container manufactured according to the method. In the present process or vessel, these quality characteristics are subject to deviations. On the one hand, the pressure between the outer container and the inner bag must be equalized, since the volume of the inner bag must be reduced as the container contents are removed. On the other hand, the container must be completely sealed, i.e.: the inner bag must be avoided from being damaged at all costs, otherwise the container cannot be used. The difficulty of satisfactorily accomplishing both tasks is discussed in WO 99/11451. For example, the wall thickness of the outer container varies within a range of 1 to 1.5mm due to the allowable strength of the wall of the outer container by the processing. In practice, the depth of cut must be set to ensure that the hole can pass through the outer container. In each case, breakage of the inner bag cannot be eliminated. Due to this, a preferred method and knife for reducing the risk of damage to the inner bag is disclosed in WO 99/11451.

Another disadvantage of the above method is that the pressure equalization holes cannot be made immediately after the forming process. The cutting process cannot be carried out on the blow molding machine, in particular when the forming mold is closed. In this way, a separate processing machine and tool must be provided for the cutting method and the processing step thereof, which inevitably increases the cost and lowers the productivity.

In addition, it is desirable to attach a pump or sprayer to the container opening of the container of the type under consideration so that material can be loaded into and removed from the inner pocket of the container through the opening. Depending on the configuration of the pump or sprayer used, the pressure equalizing aperture may be partially or completely closed by the respective pump or sprayer. In other words, it is not possible to connect any connection to the container, and therefore the particular location of the pressure equalizing hole must be taken into account in the respective embodiment. In this case, particularly unfavorable locations for the wall apertures are in the shoulder region and in the surface region of the container jacket. The most suitable location for the wall aperture, i.e. the container base, is not mentioned.

Disclosure of Invention

On this basis, it is an object of the present invention to provide a method by which pressure equalizing holes in the outer container of a container of the type in question can be made without compromising the integrity of the container. In addition, the method has the advantages of minimum process, lower cost than the method used according to the prior art, low rejection rate and high productivity.

In addition, a container is provided whose inner bag is not damaged when the pressure equalizing hole on the outer container of such a container is cut, and which has no other disadvantages.

The object of the method is achieved by the method according to the invention. According to the method, when the forming die is closed and the base seam is formed accordingly, the seam of the inner bag is at least partially axially fixed in the seam of the outer container and at least one pressure compensation opening is formed such that, after forming, the base seam is at least partially, but preferably not completely, cut off; at least a partial region of the inner pouch seam is thus held axially in the seam of the outer container, after which a radial force acting in the direction of the base seam is introduced into the base region, causing the base seam to tear open, wherein the temperature of the premold is 40 to 70 ℃ when the base seam is cut off, while the outer container is still plastically deformed to a certain extent, and is therefore permanently deformed by a force which cannot be counteracted by elastic recovery.

The walls of the outer container and the inner bag, which comprise different thermoplastics, are generally not welded together. Due to the action of the forces generated in the process of extruding the excess material through the half dies of the forming die, it is possible in each case to weld the walls of the inner bag and the outer container together. In addition, a bond is produced in the region of the base seam between the inner and outer vessel walls. This is a great advantage of the method in respect of the fixation of the inner bag in the base area. The bonding is such that: when the base seam of the outer container is torn open, one of the two sides of the base seam remains connected to the seam of the inner pouch, while the other sewn side of the outer container is not fixed to the inner pouch. In this way, even in embodiments in which the seam of the outer container is torn over its entire length, axial fixing of the inner bag is ensured despite the tearing. Securing the inner bag is particularly important in applications where insertion of the sleeve into the container and tearing off the inner bag from the base area can damage or clog the sleeve. With the method according to the invention, the inner bag is not damaged because the base seam is only partially cut off and the inner bag is firmly closed after the cutting while maintaining the weld seam of the inner bag. In contrast to the method according to the prior art, the pressure compensation opening is not produced directly by cutting, but rather by force and tearing of the base seam. Therefore, the rejection rate is low.

A variant of the method is also preferred in which an axial force substantially parallel to the longitudinal axis of the container can simply be introduced after at least partial tearing of the base seam and before the addition of a radial force to at least partially open the base seam.

Axial forces are primarily used to tear the substrate seam, while radial forces or the purpose is to create a permanent deformation of the substrate seam. Nevertheless, both forces can deform the container, in particular the base region; the tearing process of the substrate seam is preferably carried out by means of a tearing method at one point and by means of a deformation at another point.

A method in which the axial force is introduced in the form of a blow is preferred.

Variations of the method are preferred when the container is manufactured without forming a shoulder seam in the form of a squeeze seam.

The method is preferably carried out in such a way that: when the base seam is torn, the material forming the inner bag remains stuck to the ends of the outer container and base seam, on the side of the base seam, keeping the inner bag axially fixed. In this case, the pressure equalization openings between the inner bag and the outer container are located on the opposite side of the base seam.

This method is preferred when the base seam of the outer container is only partially torn and the seam of the inner bag is secured by a portion of the base seam of the outer container that is not torn.

In a preferred embodiment, the base seam is cut off in one process step and a force is applied to open and permanently deform the outer container. This means that in one process step the cutting tool and the tool tearing the seam work together and almost simultaneously. A very effective variant of the method is that the cutting of the base seam and the application of the force that opens and permanently deforms the outer container are not only effected in one operation, but also with a tool (in this case a cutting tool).

The cutting of the base seam and the application of a force which opens the outer container and permanently deforms it can also take place in a separate, subsequent step. For one or the other variant, the size of the container to be manufactured may be a decisive factor.

Method variants in which the base seam is cut off and work is carried out on the blow molding machine which exert a force which opens and permanently deforms the outer container, in particular when the container is still placed in the closed mold, are recommendable. Thus, the container with the temperature of 40-70 ℃ in the cutting process is stable. The basic advantage is that the processing machinery and equipment are reduced, and no additional process is needed. Thus, the cost can be reduced and the productivity can be improved.

In individual cases, however, it is also possible to carry out the work of cutting off the base seam and of applying a force that opens and permanently deforms the outer container on a machine connected to the blow molding machine. This also falls within the scope of the present invention.

In most cases, the container is shaped as a bottle and, in addition to being fixed in the base region, the inner bag is also fixed in the neck region. Particularly preferred here is the method in which the inner bag is clamped at least partially in the wall of the outer container when the neck of the bottle is formed. This can be easily done during the process. If the diameter of the premold is greater than the corresponding diameter of the forming die in the region of the future neck, excess material is extruded when the forming die is closed, and a weld is formed on the inner bag or the inner bag is fixed to the outer container.

With a corresponding forming die, the method can be designed such that a projection projecting outward in the radial direction is formed on the end face of the neck of the bottle. This projection is necessary if, in the latter method, the container is provided with a pump or a sprayer connected to the neck of the bottle.

In this case, the inner bag can be connected to the outer container with a part of the vertical or horizontal fold, achieving an additional fixation.

A method variant in which the projection is produced from the material of the outer container is preferred.

According to the above method, in the container according to the present invention, at least one pressure equalizing hole is formed in the base region. The aperture is formed by cutting out the substrate seam, tearing the substrate seam and deforming the substrate seam. One side of the base seam of the inner bag is bonded to the ends of the container and the base seam, so that the inner bag can be axially fixed

The preferred embodiment of the container shows that the container is bottle-shaped and has a projection on the end face of the neck of the bottle which projects outwards in the radial direction. This protruding part is necessary for mounting the pump or the sprayer. Preferably, in the region of the neck, the inner bag is clamped at least partially in the wall of the outer container, the inner bag and the outer container being connected at least partially in the region of the projection, and the joint being an upright or horizontal fold.

The invention is characterized in that the projection is made of the material of the outer container.

Drawings

The invention is explained in more detail below with reference to the attached drawing, in which:

FIG. 1 is a cross-sectional view through the central axis of the container according to a first embodiment of the container of the present invention;

FIG. 2 is a cross-sectional view of a neck of a bottle through a central axis of the container according to a second embodiment of the container of the present invention;

FIG. 3 is a cross-sectional view of the base region through the central axis of the container prior to the cutting operation;

FIG. 4 is a cross-sectional view of the base region through the central axis of the container after the cutting process;

FIG. 5 is a front view of the base of the container as viewed in the direction of the central axis of the container;

FIG. 6 is a front view of the base of the container as viewed in the direction of the central axis of the container after the tearing and deforming process; and

fig. 7 is a sectional view through the base region (detailed view of portion X in fig. 1) as seen in the direction of the central axis of the container after the tearing and deforming process.

Detailed Description

In the following description, like elements are denoted by like reference numerals.

Fig. 1 shows a cross-sectional view of a first embodiment of a container 1 through a central axis 9 of the container. In the present embodiment, the container comprising the outer container 2 and the inner bag 3 is in the shape of a bottle. At the end of the neck 6 where the container opening 8 is provided, there is a projection 7. The base seam 5 is located in the base region 4 of the container 1 in the extension of the central axis 9 of the container, around the pressure equalization opening 10. As is clearly visible in the figure, the projecting part 7 is made of the material of the outer container 2.

Fig. 2 shows a cross-sectional view of a neck 6 of a bottle through a centre line 9 of the container of the second embodiment. On the end face of the neck 6 facing the container opening 8 there is a rectangular projection 7. In contrast to the embodiment shown in fig. 1, the rectangular projection 7 is characterized by being made of two materials, outer container 2 and inner bag 3, so that, in addition to being fixed to the base region, the inner bag 3 is also fixed to the neck 6 region.

Fig. 3 shows a cross-section through the base region 4 and the base seam 5 after the blowing process and before the cutting process. The substrate slot 5 is formed by extruding excess material through the two halves of a forming die, which is shaped like a dragon tail after the actual forming process. In the region of the base seam 5, the inner bag 3 is clamped between the wall surfaces of the outer container 2.

Fig. 4 shows a sectional view of the substrate slot 5 through the substrate area 4 after the cutting method with partial cutting of the substrate slot 5.

Fig. 5 shows a front view of the base area, seen in the direction of the central axis 9 of the container, after a partial cut-out of the base seam 5. The structure of the base seam 5 is clearly visible in the figure, the centre of which is formed by the wall of the inner bag 3 and is bounded on both sides by the walls of the outer container 2. The figure also shows a radial force F which acts on the base region 4 in the direction of the base seam, tearing the base seam 5 and deforming the outer container 2. The axial force that can be selectively introduced is not shown, but can be present in this embodiment.

Fig. 6 shows a front view of the base area 4 viewed in the direction of the container central axis 9 and the base seam 5 located in the base area 4 under the effect of a radial force F acting in the direction of the base seam. It can be clearly seen how the container is deformed under force and the base seam 5 is broken to form the pressure equalizing opening 10. In this embodiment, on the side of the base seam 5, the inner bag 3 remains glued to the outer container 2 and to the end 11 of the base seam and is thus axially fixed. A pressure equalizing hole 10, which is limited by the outer container 2 and the inner bag 3, is formed on the opposite side, so that the pressure difference between the inner bag 3 and the outer container 2 can be compensated.

Fig. 7 shows a sectional view of the base region 4 through the central axis 9 of the container and the base seam 5 located therein. The pressure equalizing opening 10 is clearly visible between the inner bag 3 and the outer container 2.

List of reference symbols

1-Container 2-outer Container

3-inner bag 4-base region

5-basal seam 6-neck of bottle

7-projection 8-Container opening

9-center axis of the vessel

10-pressure balance hole

11-end of substrate seam

Claims (24)

1. A method of manufacturing a container (1) with a container opening (8), the container (1) having a substantially rigid outer container (2), an inner bag (3) placed therein, the inner bag being in contact with the contents of the container, and a pressure equalizing aperture (10), the outer and inner containers comprising different thermoplastics which are not bonded to each other; pressure equalizing apertures (10) are provided in the outer container (2) for equalizing the pressure difference between the outer container (2) and the inner bag (3), wherein a preliminary molding comprising two coaxial tubes of sufficient length for the manufacture of the container is initially manufactured by coextrusion between two open half-moulds of a forming mould which is closed, with the formation of an outwardly projecting base seam (5), excess material in the base region (4) of the container to be manufactured being squeezed out, the material of the outer container (2) in contact with the area of the seam being welded together, and the tubes constituting the inner bag being clamped, axially fixed and welded between wall parts of the outer container (2); the inner bag (3) is subjected to pressure, so that the preliminary moulded piece rests from the inside against the contour of the forming die, characterized in that, when the forming die is closed and the base seam (5) is formed accordingly, the seam of the inner bag (3) is at least partially axially fixed in the seam of the outer container and at least one pressure compensation opening (10) is formed, so that, after forming, the base seam (5) is at least partially cut off; radial forces acting in the direction of the base seam act on the base region (4) and cause the base seam (5) to tear, wherein the temperature of the premold is 40 to 70 ℃ and the base seam is cut off while the outer container (2) is still plastically deformed to a certain extent, so that the permanent deformation is produced by forces which cannot be counteracted by elastic recovery.

2. A method according to claim 1, characterized in that, when the base seam (5) is at least partly cut and before the introduction of the radial force, an axial force is introduced which is substantially parallel to the longitudinal axis of the container, causing the base seam to tear at least partly.

3. A method according to claim 2, wherein the axial force is introduced in the form of a blowing.

4. A method according to any preceding claim, wherein the container is manufactured without forming a shoulder seam in the form of a squeeze seam.

5. A method according to claim 1, 2 or 3, characterized in that the material constituting the inner bag (3) remains stuck to the outer container (2) and to the end (11) of the base seam (5) on one side of the base seam (5) when the base seam (5) is at least partially torn, remaining axially fixed.

6. A method according to claim 1, 2 or 3, characterized in that the base seam (5) of the outer container (2) is only partially torn, while the seam of the inner bag (3) is secured by the tear-free part of the base seam of the outer container (2).

7. A method according to claim 1, 2 or 3, characterized in that the base seam (5) is cut off and a force is applied in one operation simultaneously to open the outer container (2) and to permanently deform the outer container (2).

8. A method according to claim 1, 2 or 3, characterized in that the base seam (5) is cut and a force is applied to open the outer container (2) and to permanently deform the outer container (2) is maintained separately in a separate process step.

9. A method as claimed in claim 1, 2 or 3, characterized in that the cutting of the base seam (5) and the application of the force for opening the outer container (2) and for permanently deforming the outer container (2) are carried out on a blow moulding machine.

10. A method as claimed in claim 9, wherein the container (1) is still in the forming mould.

11. A method as claimed in claim 8, wherein cutting the base seam (5) and applying the force to open the outer container (2) and permanently deform the outer container (2) are carried out on a machine connected to the blow moulding machine.

12. A method as claimed in claim 1, characterized in that the container (1) is formed in the shape of a bottle.

13. Method according to claim 12, characterized in that, in addition to the fixing in the base region (4), the inner bag (3) is also fixed in the region of the bottle neck (6).

14. Method according to claim 13, characterized in that the inner bag (3) is clamped at least partially in the wall of the outer container (2) during the formation of the neck (6) of the bottle.

15. A method as claimed in any one of claims 12 to 14, characterized in that a radially outwardly projecting projection (7) is formed on the end face of the neck (6).

16. A method according to claim 15, characterized in that the inner bag (3) and the outer container (2) are connected by means of vertical or horizontal folds in the area of the projecting part (7).

17. A method as claimed in claim 15, characterized in that the projecting part (7) is made exclusively of the material of the outer container (2).

18. Container (1) with a container opening (8), substantially comprising a rigid outer container (2) and an inner bag (3) arranged therein which is in contact with the container contents, manufactured according to claim 1, characterized in that at least one pressure equalizing opening (10) is formed in the base area (4) by a base seam (5) which is formed during the moulding process, which seam is at least partly cut off and which base seam (5) is deformed into a pressure equalizing opening by tearing the seam by introducing a radial force acting in the direction of the base seam; the inner bag (3) is made of a material which is still adhered to the outer container (2) and the end of the seam on one side of the base seam (5) so that the inner bag (3) is axially fixed; at the same time, at least one pressure equalization opening (10) is formed between the outer side of the inner bag (3) and the inner side of the outer container (2) to provide a constant pressure equalization.

19. Container according to claim 18, characterized in that the container (1) is in the shape of a bottle.

20. Container according to claim 19, characterized in that the inner bag (3) is secured in the region of the neck (6) of the bottle in addition to the base region (4).

21. Container according to claim 20, characterized in that the inner bag (3) is clamped at least partially in the wall of the outer container (2) in the region of the neck (6) of the bottle.

22. A container as claimed in any one of claims 19 to 21, characterized in that the end face of the neck (6) is provided with a projection (7) which projects outwards in the radial direction.

23. A container according to claim 22, characterized in that the inner bag (3) and the outer container (2) are connected at least partly in the area of the protruding part (7) and that the joint is an upright or horizontal fold.

24. A container according to claim 22, characterized in that the projecting part (7) is made exclusively of the material of the outer container (2).