HRP20020797A2 - Method for producing a container having a pressure compensation opening, and container produced according to said method - Google Patents

Description

The invention relates to a process for producing a container that has an opening, and which consists of an outer container of mostly rigid shape and an inner bag that is located in the outer container and which will later come into contact with the contents of the container, wherein the outer container and the inner bags made in any case from thermoplastic polymer materials that cannot be connected to each other, and in the outer container there is an opening to equalize the pressure difference that exists between the outer container and the inner bag, whereby first the preparation is produced by the process of co-extrusion blowing between the open halves of the blowing mold consisting of two coaxial hoses, which preparation is of sufficient length to produce a container, the blow mold is then closed, whereby, with the formation of a joining line facing outwards, the excess material in the area of the bottom of the container being produced is compressed so that to weld the material of parts of the outer s in the area of the joining line parts that touch each other, so that the hose that forms the inner bag is squeezed between parts of the walls of the outer container, axially fixed and welded, and the inner bag is exposed to pressure, so that the preparation with its walls from the inside rests on the walls of the blow mold.

Furthermore, the invention relates primarily to a container with an opening which is produced by this process and which consists of

mainly from the outer container of a rigid shape in which there is an inner bag which later comes into contact with the contents of the container.

A process of this type is described in WO 99/11451. A characteristic feature of this procedure is that the opening for pressure equalization, through which the pressure difference between the outer container and the inner bag is equalized, is made primarily - as a hole in the shape of a lens or an ellipse in the outer container, and this hole after the completion of a special of the molding process, using a cutting tool, is created by cutting off part of the wall of the outer container.

This means that the outer wall, against which the very thin flexible inner bag rests, must be completely cut away in at least one very small area, without damaging the inner bag. The processing of the outer container, carried out in this way, undoubtedly involves contact between the two parts of the cutting tool and the inner bag. Basically, the most important features of the quality of the process and the container produced by that process cannot be realized simultaneously to an equally high degree. They differ in the proposed procedure, i.e. the container. First, it must be possible to equalize the pressure between the outer container and the inner bag, which is associated with the decrease in volume due to the emptying of the contents of the container. On the other hand, the container must be completely leak-proof, that is, damage to the inner bag must be avoided under all circumstances, because the container then becomes unusable. The difficulty of satisfactorily solving both tasks was discussed in WO 99/11451. So, for example, it is claimed that due to the wall thickness tolerances of the outer container, which are a consequence of the production conditions, and whose wall thickness can be defined between 1 and 1.5 mm, the cutting depth should be adjusted in practice so that a hole can be created by cutting it really goes through the outer tank. In any case, it is not possible to avoid damage to the inner bag. For this reason, WO 99/11451 describes a favorable cutting process and a tool used for this purpose to minimize the risk of damage to the inner bag.

A further disadvantage of the described procedure is that the opening for pressure equalization is not made directly in the continuation of the molding process. Cutting cannot be done on a plastic blow molding machine, especially not on a plastic blowing machine with a closed blow mold. The additional processing machine required for the proposed cutting process, i.e. its tool and work operations that become necessary due to the particular cutting process, lead to an increase in costs and a decrease in productivity.

In addition, it may be desirable to connect a pump, or an atomizer, to the opening of the tank of the type in question, with which the contents of the inner bag are ejected, or dosed. Depending on the particular design of the used pump, that is, the used atomizer, the opening for pressure equalization may be partially or completely closed due to the adapted atomizer, or the adapted pump. In other words, any extension cannot be adapted to the tank considered here, but the special position of the pressure equalization opening of the respective embodiment must be taken into account. As particularly unfavorable in this respect for the position of the opening in the wall, the positions in the upper area and in the area of the surface of the tank shell should be mentioned. The bottom of the tank is not specifically stated as the most favorable area of the tank for the opening in the wall.

On this basis, the task of the proposed invention is to provide a process that enables the creation of an opening for pressure equalization, which opening is located in the external tank of the considered type, without jeopardizing the impermeability of the tank, whereby the process must have a minimum number of working steps and, in compared to procedures applied according to the state of the art, it must not cause higher costs and must at the same time enable a smaller amount of waste, i.e. higher productivity.

In addition, it is necessary to provide a container that has an opening for pressure equalization in its outer container, whereby the cutting of this opening must not cause damage to the inner bag, and the container must not have any of the other listed defects.

The posed problem is solved by the method according to the invention, according to which, when closing the blow mold, and the associated shaping of the lower connection line, the connection line of the inner bag is at least partially fixed axially in the connection line of the outer container, and thus at least one opening is created for pressure equalization, so that then the bottom joint line, after shaping, is cut off at least partially, but preferably not completely, so that at least part of the joint line of the inner bag remains fixed in the joint line of the outer container, and then acts with a radial force in the direction of the joint line in the bottom region, so to break the lower joining line, whereby the temperature of the preparation when cutting the lower joining line is between 40°C and 70°C and the outer container can still be plastically deformed to a certain extent, so that the deformation caused by this force is a permanent deformation and cannot be corrected with an elastic return.

The walls of the inner bag and the outer container, which are made of different thermoplastic polymer materials, generally cannot be welded together. As a result of the force exerted during the extrusion of the excessive material with the halves of the blow mold, they are welded together on one side of the wall of the inner bag and on the other side of the wall of the outer container. In addition, in the area of the lower joining line, sticking occurs between the walls of the inner bag and the outer container. This is an important advantage of the procedure regarding the fastening of the inner bag in the area of the bottom. At the same time, this bonding is such that when the lower connection line of the outer container is torn, one of the two sides of the connection line of the inner bag remains connected, while the other side of the connection line of the outer container is no longer fixed with the connection line of the inner bag. In this way, despite the interruption, the axial fastening of the inner container is enabled, and only in the embodiment in which the connecting line of the outer container is interrupted along its entire length.

The fastening of the inner container is especially important in cases of application in which a tube is inserted into the container and tearing the inner bag from the bottom area would lead to damage, or to clogging of the tube. With the method according to the invention, damage to the inner bag is excluded, because the lower connection line is only partially cut off, and thus the inner bag, even after the cutting is completed, remains firmly closed with the remaining welded joint of the inner bag. Contrary to the procedure from the state of the art, the opening for pressure equalization is not made directly by cutting, but by applying force and breaking the connection line. The amount of waste is minimal.

Versions of the procedure are preferred, in which, after at least partial cutting of the lower connection line and before the radial force, an axial force is applied for a short time, which acts mainly parallel to the longitudinal axis of the container, so that the lower connection line is at least partially broken.

The axially applied force serves primarily to tear the lower joint line, while the effect, or benefit, of the radially applied force is primarily in the permanent deformation of the lower joint line. Despite this, both forces act on the deformation of the container, especially the bottom area, and also on the tearing process, whereby in one case it is primarily tearing, and in the other case it is primarily deformation.

Preference is given to procedures that are characterized by the fact that the axial force is applied in the form of an impact.

Advantageous are those versions of the process in which the production of the container takes place without making the upper joint line in the form of a compressed joint line.

The procedure is primarily carried out so that when the lower joining line is torn, the material of the inner bag remains glued on one side of the lower joining line on the outer container, thus obtaining a proper axial fastening. In this case, the opening for equalizing the pressure between the inner bag and the outer container is located on the opposite side of the lower connection line.

A favorable procedure is that the lower connection line of the outer container is only partially interrupted and the connection line of the inner bag is fixed with the unbroken part of the connection line of the outer container.

In the preferred procedure, what happens is that the cutting of the lower connection line and the application of the force, which acts on the outer container so that it opens and permanently deforms it, take place simultaneously in one working step. This can be done by setting the cutting tool and the joint line tearing tool in series and working almost simultaneously in one work step. A particularly effective version of the procedure is in which the breaking of the lower connection line and the introduction of the force acting on the outer container in the sense of opening and permanent deformation is realized not only simultaneously in one working step, but also in one tool, in this case in the cutting tool.

It is recommended that the cutting of the lower connection line and the introduction of a force that opens and permanently deforms the outer container is carried out in separate working steps that follow one another. The decisive criterion for one or the other version can be the size of the container that is to be made.

A version of the process can be recommended in which the cutting of the lower joint line and the introduction of a force that opens and permanently deforms the outer container is done in a plastic blow molding machine, especially if the container is still inside a closed blow mold. This stabilizes the hot tank temperature between 40 and 70°C during cutting. The main advantage is the minimum number of working machines, or devices, and the elimination of additional work steps. This reduces costs and increases productivity.

However, in some cases, it may be advisable to cut the lower joint line and introduce a force that opens and permanently deforms the outer container on a machine connected behind the plastic blower. This also falls within the scope of the invention.

In most cases, it is a process by which a container is made in the shape of a bottle and the inner bag is additionally fixed in the area of the bottom and also in the area of the neck of the bottle, due to reinforcement. Processes in which the inner bag is pressed at least partially into the walls of the outer container when shaping the neck of the bottle are mentioned here as particularly advantageous. This can be easily achieved during the course of the procedure. If the diameter of the preparation in the area of the future bottle neck is larger than the corresponding diameter of the blow mold, when the blow mold is closed, excess material is squeezed and a welded connection line is created on the inner bag, i.e. the inner bag is fastened to the outer container.

The process can be carried out by using a suitable blow mold to produce a bottle neck with a bulge on its face, which bulge projects outwards in a radial direction. This may be necessary if, in the later process, the tank has to be equipped with a pump, that is, with an atomizer that will first of all be adapted to the neck of the bottle.

In this case, the inner bag can be connected to the outer container in the region of the protrusion by means of a part of the standing or lying fold and thus its additional fastening can be obtained.

Preference is given to versions of the procedure in which the protrusion is formed exclusively from the material of the outer container.

In accordance with the described procedure, in the container according to the invention, at least one opening for pressure equalization is located in the area of the bottom and is created by cutting, tearing or reshaping the lower connection line, whereby the inner bag remains glued on the side of the lower connection line on the outer container and at the ends of the line connections and thus it is axially fixed.

In advantageous forms of the container, the container is made in the shape of a bottle and the neck of the bottle has a protrusion on its front side that protrudes in the radial direction, and which protrusion is necessary for adjusting the pump, that is, the atomizer. However, also the additional fastening in the area of the bottle neck and its implementation fall within the scope of the invention in accordance with patent claims 21 and 23. Also a feature of the invention is the one according to which the protrusion is made exclusively from the material of the outer container.

The invention is further explained below with the help of various figures of embodiments. Thereby:

Figure 1 shows a cross-section through the first example of the tank design in the direction of the central axis of the tank,

figure 2 shows a section through the neck of the bottle of the second embodiment of the container in the direction of the central axis of the container,

Figure 3 shows a section through the area of the bottom in the direction of the central axis of the tank, before cutting,

Figure 4 shows a section through the area of the bottom in the direction of the central axis of the tank, after cutting,

Figure 5 shows the outline of the bottom of the tank in the direction of the central axis of the tank, before the tear-off and deformation procedures,

Figure 6 shows the outline of the bottom of the tank in the direction of the central axis of the tank, after the tear-off and deformation procedures,

Figure 7 shows a section through the bottom area in the direction of the central axis of the tank, after the tear-off and deformation procedures (detail X from Figure 1).

In the following description, equal parts are marked with the same numbers.

Figure 1 shows a section through the tank 1 in the direction of the central axis 9 of the tank of one embodiment. The container, which consists of an outer container 2 and an inner bag 3, in the proposed example is made in the shape of a bottle. It has a protrusion 7 on its neck of the bottle 6, which is located at the end of the neck of the bottle 6 on which the opening of the container is located. In the area 4 of the bottom of the tank 1, in the extension of the central axis 9 of the tank, there is a lower connection line 5 around its associated opening 10 for pressure equalization. It is clearly shown that the protrusion 7 is made exclusively from the material of the outer container 2.

Figure 2 shows a section through the neck of the bottle 6 in the direction of the central axis of the container of the second embodiment of the container. The neck of the bottle 6 on its front side, directed towards the opening of the container 8, has a rectangular protrusion 7. Contrary to the embodiment shown in Figure 1, the rectangular protrusion 7 is special in that it is also made from the material of the outer container 2, as well as from the material used to make the inner bag, so that the inner bag 3, in addition to being fixed in the area of the bottom, is also specially fixed in the area of the neck of the bottle 6.

Figure 3 shows a section through the bottom area 4 and the joining line 5 which is here after blowing but before cutting. The joining line 5, which is formed by squeezing the excess material using the two halves of the blow mold, in accordance with its molding process, has the shape of a dragon's tail. The inner bag 3 is compressed in the area of the bottom line 5 between the walls of the outer container 2.

Figure 4 shows a section through the bottom region 4 and the associated joint line 5, which is shown here after being cut away, with the lower joint line 5 partially cut away.

Figure 5 shows a plan of the bottom area with a view in the direction of the central axis 9 of the container after partially cutting off the lower joint line 5. The construction of the lower joint line 5 is clearly visible, which was formed in the middle from the wall of the inner bag and is bounded by two sides of the walls of the outer container 2 Also indicated is the effect of force F radially in the direction of the joining line, which force acts in the area of the bottom 4, so that it would break the lower joining line 5 and deform the outer tank 2. The optimally applied axial force in the proposed embodiment is not marked, that is, it is not foreseen . Figure 6 shows a plan of the bottom area 4 with a view in the direction of the central axis 9 of the tank and the joining line 5 located in the bottom area 4, with the force F acting radially in the direction of the joining line. It is clearly shown how the container is deformed by force and how the connection line 5 is torn, so that the opening 10 is created for pressure equalization. In the particular embodiment shown here, the inner bag 3 remains glued on one side of the lower joining line 5 on the outer container 2 and at the ends of the joining line 11 and is thus axially fixed. On the opposite side, there is an opening 10 for pressure equalization, which is bordered by the outer container 2 and the inner bag 3, and thus the pressure difference that exists between the inner bag and the outer container can be equalized.

Figure 7 shows a section in the direction of the central axis 9 of the container through the area of the lower connection line 4 and the corresponding connection line 5. The opening 10 for equalizing the pressure between the inner bag 3 and the outer container 2 is clearly visible.

Explanation of the numbers in the pictures

1. container

2. external tank

3. inner bag

4. bottom area

5. bottom joining line

6. bottle neck

7. bulge

8. tank opening

9. central axis of the tank

10. opening for pressure equalization

11. the ends of the lower joining line

Claims (24)

1. A process for producing a container (1) with an opening (8), having an outer container (2) of generally rigid shape in which there is an inner bag (3) that comes into contact with the contents that will later be in the container, in each in the case of different thermoplastic polymer materials that do not connect to each other, and the opening (10) in the outer tank for equalizing the pressure that exists between the outer tank (2) and the inner bag (3), whereby first by the process of co-extrusion blowing between the open halves of the mold it is produced preparation, which consists of two coaxial hoses, which preparation has sufficient length to make the container, then the mold is closed and with the formation of the bottom line (5) facing outwards, the excess material of making the container is cut off in the area (4) of the bottom so that the parts of the material of the outer container that touch each other in the area of the joining line are welded to each other, so that the hose that forms the inner bag (3) is squeezed between the parts of the walls of the outer sp of the belt (2), it is axially fixed and welded, and the inner bag (3) is exposed to pressure so that the walls of the preparation fit inside the walls of the blowing mold, indicated by the fact that when closing the blowing mold and the associated shaping of the bottom line (5) connection, the connection line of the inner bag (3) is at least partially fixed axially in the connection line of the outer container and thereby forms at least one opening (10) for pressure equalization, and that immediately after forming the lower connection line (5) is at least partially cut and exposed is a force acting radially in the direction of the joining line in the lower area (4) so that the lower joining line (5) breaks, whereby the temperature of the preparation when cutting the lower joining line (5) is between 40°C and 70°C and the outer container (2) can still be plastically deformed to a certain extent, so that the deformation caused by the action of the force represents a permanent deformation and cannot be corrected with elastic recovery. 2. The method according to claim 1, characterized in that after at least partial cutting of the lower connection line and before the introduction of the radial force, the axial force acts at least for a short time mainly parallel to the longitudinal axis of the container so that the lower connection line is at least partially broken. 3. The method according to claim 1 or 2, characterized in that the axial force acts in the form of an impact. 4. The method according to any preceding claim, characterized by the fact that the production of the container takes place without creating an upper joining line in the form of an imprinted joining line. 5. The method according to any previous claim, characterized by the fact that when the lower joining line (5) is torn, the material for making the inner bag (3) remains glued to one side of the outer container (2) and at the ends of the lower joining line (11), which axial bracing is obtained. 6. The method according to any preceding claim, characterized in that the connecting line (5) of the outer container (2) is broken only partially and the connecting line of the inner bag (3) is fixed with the unbroken part of the lower connecting line of the outer container (2). 7. The method according to any preceding claim, characterized in that the cutting of the lower connection line (5) and the action of the force that opens and permanently deforms the outer container (2) are performed simultaneously in one working step. 8. The method according to any claim 1 to 6, characterized in that the cutting of the lower connection line (5) and the action of the force that opens and permanently deforms the outer container (2) are performed separately in separate working steps. 9. The method according to any preceding claim, characterized in that the cutting of the lower connection line (5) and the action of the force that opens and permanently deforms the outer container (2) is performed on a plastic blower. 10. The method according to claim 9, characterized in that the container (1) is still inside the blow mold. 11. The method according to any of claims 1 to 8, characterized in that the cutting of the lower joining line (5) and the action of the force that opens and permanently deforms the outer container (2) is performed on a machine connected behind the plastic blower. 12. The method according to any preceding claim, characterized in that the container (1) has the shape of a bottle. 13. The method according to claim 12, characterized by the fact that the inner bag (3) is additionally fixed in the area of the neck (6) of the bottle due to its fastening in the area of the bottom (4). 14. The method according to claim 13, characterized in that when making the neck (6) of the bottle, the inner bag (3) is at least partially pressed into the walls of the outer container. 15. The method according to any of claims 12 to 14, characterized in that the neck (6) of the bottle, on its front side, has a protrusion (7) that protrudes radially outwards. 16. The method according to claim 15, characterized in that the inner bag (3) in the region of the protrusion (7) is connected to the outer container (2) by means of a part of a standing or lying fold. 17. The method according to claim 15, characterized in that the protrusion (7) is made exclusively from the material used to make the outer container (2). 18. A container (1) with an opening (8), which mainly consists of a rigid outer container (2) and an inner bag (2) inside it, which will later come into contact with the contents of the container, produced primarily by the process according to any of the claims 1 to 17, characterized by the fact that in the area of the bottom (4) there is at least one opening for equalizing the pressure, and at least partially cutting off the lower connection line (5) that is formed during the molding process and tearing and deforming the lower connection line (5 ) by the action of the radial force in the direction of the joining line, the material for making the inner bag (3) remains glued on one side of the lower joining line (5) on the outer container (2) and at the ends of the joining line, which achieves the axial fastening of the inner bag (3) and at the same time at least one pressure equalization opening (10) is created between the outside of the inner bag (3) and the inside of the outer container (2), which ensures constant pressure equalization. 19. Container according to claim 18, characterized in that it is made in the shape of a bottle. 20. Container according to claim 19, characterized in that the inner bag (3) is additionally fixed in the area of the bottom (4) in the area of the bottle neck. 21. Container according to claim 20, characterized in that the inner bag (3) in the area of the bottle neck (6) is at least partially compressed in the walls of the outer container (2). 22. Container according to any one of claims 19 to 21, characterized in that the neck of the bottle (6) on its front side has a protrusion (7) that protrudes outwards in the radial direction. 23. Container according to claim 22, characterized in that the connection of the inner bag (3) with the outer container (2) is located in the region of the bulge (7) and is made as part of a standing or lying fold. 24. Container according to claim 22, characterized in that the protrusion (7) is made exclusively from the material of the outer container (2).