LIQUID CONTAINER, METHOD AND DEVICE FOR CONSTRUCTING SUCH A CONTAINER
The polypropylene tube with an aluminum film and induction sealing, combined with a coextruded aluminum cover and IML label, addresses the limitations of existing containers by ensuring robustness, sterilizability, and decorative capabilities, while maintaining a high barrier to molecules and facilitating easy opening.
Patent Information
- Application Number
- FR2023007853
- Authority / Receiving Office
- FR · FR
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2023-07-21
- Publication Date
- 2025-01-24
- Estimated Expiration
- Not applicable · inactive patent
AI Technical Summary
Existing liquid containers, such as glass ampoules and synthetic bottles, face issues with brittleness, logistical constraints, skin cuts, material permeability, high cost, and inability to be sterilized or decorated, while flexible aluminum containers are difficult to open and require preservatives.
A polypropylene tube sealed with an aluminum film using induction sealing, combined with a coextruded aluminum cover and IML label, ensures robustness, sterilizability, and easy opening, with a controlled seal and decorative capabilities, while maintaining a high barrier to atoms and molecules.
The solution provides a reliable, economical, and user-friendly container with a high barrier to oxygen and other molecules, allowing for precise production rates and easy opening, while eliminating the need for temperature management and reducing material deformation risks.
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Abstract
Description
Title of the invention: LIQUID CONTAINER, METHOD AND DEVICE FOR PRODUCING SUCH A CONTAINER Technical field of the invention
[0001] The present invention relates to a liquid container, a method and a device for constituting such a container. It applies, in particular, to the constitution of doses of medicines and drinkable products, for example food supplements or energy drinks. State of the art
[0002] Traditionally, containers for doses of liquid medication were cylindrical glass ampoules with two points. Their advantages include their ability to contain a single material, that is to say a uniform material, the barrier that glass represents, the impermeability of glass to gases as well as liquids and their low cost. However, glass ampoules with two points have many disadvantages. First of all, glass is a brittle and heavy material, which therefore imposes significant logistical constraints. In addition, once opened by breaking one of their points, these ampoules can cause cuts to the user's skin. There are also risks, when opening by breaking a point, that glass fragments accompany the liquid and are swallowed by the user, with the risk of cutting their digestive system.Glass also does not allow for printing or decoration other than monochrome and low resolution.
[0003] A development of this two-pointed bulb is the single-pointed cylindrical glass "bottle" bulb. This bulb has the same disadvantages as the two-pointed bulb. In addition, its manufacture is more expensive than that of the two-pointed bulb.
[0004] Bottles made of synthetic material have also been used. These are single-dose containers made of synthetic material closed by a screw cap. These bottles have the advantages of being robust and non-brittle, that they can be filled individually and that they can be decorated in four-color process by applying a label. On the other hand, their synthetic material does not constitute a barrier for atoms or molecules, which can lead to deterioration of their contents, or even the formation of undesirable or dangerous molecules, for example by oxidation or penetration of atoms or molecules coming from the glue or the dyes of the label. In addition, these bottles cannot be sterilized and their cost is high.
[0005] The “Unicadose” ® have the advantages of being robust and sterilizable, but with risks of deformation and leakage. They have the following main disadvantages. Their material does not constitute a barrier for atoms or molecules, particularly in their breakable zone, which is particularly thin (of the order of a few hundredths of a millimeter thick) which increases porosity to oxygen. Since their sealing is obtained by interlocking, they present risks of leakage and the presence of liquid in the assembled part. Their cost price is high. Their breakability is not controlled because the reduced thickness of material at the opening varies with the wear of the mold. Their filling is collective or semi-collective, involving a very heterogeneous dosage with a significant risk of non-compliant filling. Their decoration is necessarily monochrome.
[0006] Sticks® are flexible aluminum containers. They have the advantages of being robust and individually refillable. They can be decorated in four-color process and their walls constitute barriers for atoms and molecules, in particular oxygen. However, they have many disadvantages. They cannot be sterilized, which requires the use of preservatives. They have a small capacity and their opening is difficult for an average user. Summary of the invention
[0007] The present invention relates to the manufacture of containers for liquids, for example single-dose liquid food supplements (unitary dose consumed), which meet all or part of the following criteria: - robust, - sterilizable, - decoratable, - easy to open by any user, - economical, - the dosage of which is reliable, and - of which more than 90% of the surface constitutes a barrier for atoms and molecules, notably oxygen.
[0008] According to a first aspect, the present invention relates to a container in the form of a
[0009] polypropylene tube sealed with an aluminum film. To ensure the quality of the assembly of these materials, and to ensure the perfect sealing of the container, despite the thermal and mechanical stress due to the sterilization process, while allowing opening without tools for the consumer, and respecting the constraints of production rates, the use of a direct thermal head is impossible. Indeed, on a filled container, the heat necessary for the fusion of the materials spreads to all the parts near the punch. The expansion of the residual air chamber above the liquid which results creates an increase in the pressure in the tube which, in turn, generates a thrust on the cover during heating.
[0010] When removing the punch from the head, while the polypropylene is still molten, this thrust causes the seal to detach. A seal cannot therefore be obtained.
[0011] According to embodiments of the invention, an induction sealing head is used. With this technology, the seal becomes the hot part of the process. The induction field is directed primarily towards the parts in contact on the periphery of the seal in order to reduce heat loss. This has the effect of limiting heating of the residual air chamber. To achieve this peripheral induction, an element is provided that disrupts the magnetic field, for example made of graphite positioned on the central part of the seal.
[0012] Preferably, the cover is made of coextruded aluminum with a layer of polypropylene, which improves the adhesion of the cover to the polypropylene tube.
[0013] In embodiments, once the fusion and therefore the assembly have been carried out, the induction is stopped and the punch of the head remains under pressure until the polypropylene has cooled. Since the polypropylene is no longer molten when the punch is withdrawn, and since the air pressure is almost zero, nothing disrupts the connection and the seal obtained is controlled.
[0014] In addition, the use of this technology allows for a higher rate and eliminates the need for temperature management (preheating, cooling and heating control throughout production). The management of the values of the power and time parameters of the phases, combined with air cooling during the rest phases during the cycle, makes it possible to guarantee the reproducibility of operations throughout the production period with very high precision.
[0015] Another risk associated with heat sealing is that the diffusion of the molten material during sealing is not controlled. This creates excess material outside the generatrices of the tube, whether cylindrical or conical, which can rise up onto the lid. This generates a significant increase in the external diameter of the tube, a coarse result and major difficulties for the consumer to open the container. This very heterogeneous difficulty cannot be resolved with the use of conventional heat sealing.
[0016] According to another aspect of the invention, possibly complementary to the first, the quantity of material at the periphery of the tube in the sealing zone is reduced so that the excess molten material remains in the outer perimeter of the generatrices of the tube.
[0017] In embodiments of each aspect of the invention, the magnetic induction flux is oriented so that the melting occurs preferentially on the part of the seal facing the inner perimeter of the tube. The molten material on which the pressure is applied is therefore softer on the inner wall of the tube than on its outer wall, so that this material shrinks towards the center of the cover. However, since only the cover is hot, no fusion of the tube can occur outside the contact zone of the two parts.
[0018] All of these measures allow us to increase the contact surface between the tube and the seal for better sealing without degrading the ease of use of the seal when opened manually by a user.
[0019] According to a third aspect, possibly complementary to one and / or the other of the first two aspects, for the decoration, an IML label (acronym for "In Mold Labeling" for in-mold labeling) is used. This label allows a four-color decoration to be obtained. The use of "crystal" polypropylene tube, therefore without additives, is an undeniable qualitative advantage for the target market.
[0020] In embodiments, the label is made of a "barrier" material, or support, i.e. one that does not allow oxygen to pass through its thickness. This characteristic solves the problem of polypropylene containers which are relatively porous to oxygen.
[0021] It is noted that the use of other common materials such as PET (polyethylene), which may have better barrier properties, is incompatible with the sterilization heat treatment.
[0022] Preferably, the single-dose object of the invention is a relatively long and narrow tube, the dimension of which parallel to the axis of rotational symmetry is, for example, greater than five times the diameter.
[0023] However, to maintain the IML label in the mold during the injection of the material, it is only known to charge the latter with an electrostatic charge to force it to stick to the walls of the mold. But, the diameter of the tube being very small, the opposite walls of the mold cavity are very close and disrupt the homogeneous distribution of the label. This technology cannot therefore be used.
[0024] According to a fourth aspect of the invention, the label is held in place in the mold using venturi (air suction) through openings in the external mold.
[0025] In embodiments, the label does not cover the entire circumference of the tube. The air suction device is then configured to be wide enough to allow the passage of air and a sufficient suction effect without allowing the suction of material injected into the mold, which would block the device in the event of absence or lack of integrity of the label during injection. Preferably, the diameter of the suction channels is between 5 and 15 microns. Preferably, the suction device comprises at least two channels per mold, positioned near the ends of the part to be molded. Brief description of the figures
[0026] Other advantages, aims and characteristics of the invention will emerge from the description which follows, given for explanatory and in no way limiting purposes with regard to the appended drawings, in which:
[0027] [Fig-1] represents, schematically and in top view, a manufacturing unit object of the invention,
[0028] [Fig.2] represents, in top view, the temperature on the circular surface of a lid during the closing of a container,
[0029] [Fig.3] represents a timing diagram for activating a heating component of a cover during the closing of a container,
[0030] [Fig.4] represents a side view and a top view of an example of a container which is the subject of the invention,
[0031] [Fig.5] represents, in sectional view referenced in [Fig.4], the container illustrated in [Fig.4],
[0032] [Fig.6] represents a detail of [Fig.5] referenced in [Fig.5],
[0033] [Fig.7] represents, in section, a bottom part of the container illustrated in figures 4 to 6, And
[0034] [Fig.8] represents, in section, a part of the mouth, before sealing, of the container illustrated in figures 4 to 7. Description of the embodiments
[0035] Throughout the description, the following terms are used: - “Monodose”: a single-dose container made of synthetic material. - “Unit filling”: action of filling the single-dose unit by unit, controlling the quantity of liquid inserted into the single-dose. - “Collective filling”: action of filling single doses collectively.
[0036] - “Sterilization”: heat treatment at a temperature above 100°C and lasting between 12 and 30 min. - “Tyndallization”: heat treatment at a temperature below 100°C (generally 70°C) for a duration of 60 mm reproduced 3 times at 24-hour intervals (Used for heat-sensitive raw materials). - “Barrier”: term used to describe the absence of porosity to oxygen in materials. Examples
[0037] The manufacture of 15 ml single doses of pharmaceutical grade polypropylene sealed using a co-extruded aluminium seal with a layer of polypropylene is described below.
[0038] The first difficulty lies in the quality of the assembly of these materials.
[0039] This must ensure the perfect sealing of the container, despite the stress due to the sterilization process, while allowing opening without tools for the consumer, all while respecting the constraints of production rates.
[0040] The use of a direct thermal head is impossible on a filled container because the heat required to melt the materials spreads to all parts near the punch. The resulting heating of the residual air chamber causes an increase in pressure in the tube which, in turn, generates a thrust on the seal during heating. When the punch is removed from the head, while the polypropylene is still molten, this thrust causes the seal to detach. A seal cannot therefore be obtained.
[0041] In the embodiment detailed here, an induction sealing head is used. With this technology, the seal becomes the hot part of the process. The induction field is directed primarily towards the parts in contact at the periphery of the seal opposite the thickness of the tube at its mouth, in order to reduce heat loss. This has the effect of limiting heating of the air chamber.
[0042] Furthermore, once the fusion and therefore the assembly have been carried out, the induction is stopped and the punch of the head remains under pressure until the polypropylene has cooled.
[0043] Since the latter is no longer molten when the punch is removed, and the air pressure is almost zero, nothing disrupts the connection and the seal obtained is controlled.
[0044] In addition, the use of this technology allows for a higher rate and eliminates the need for temperature management (preheating, cooling and heating control throughout production).
[0045] The management of the values of the power and time parameters of the phases, combined with air cooling during the rest phases during the cycle, makes it possible to guarantee the reproducibility of the operations throughout the production period with very high precision.
[0046] Another risk associated with heat sealing is also that the diffusion of the molten material during sealing could not be controlled. This would have the effect of creating excess material outside the generatrices of the cylindrical or conical tube, these excesses being able to rise up onto the seal. This would generate a significant increase in the external diameter of the tube, a coarse result, a risk of cutting the consumer's lips, and significant difficulties for the consumer to open the container. These risks cannot be avoided with the use of conventional heat sealing.
[0047] In the container detailed here, in addition to the use of induction, the quantity of material at the periphery of the tube is reduced, as illustrated in [Fig.8]: the internal diameter of the tube is, before sealing, identical over the entire length of the tube, including its mouth, but the external diameter of the tube is reduced near the mouth. In [Fig. 8], the reduction in the external diameter is 0.5 millimeters, the thickness of the tube decreasing from 1.00 millimeters to 0.75 millimeters over the last half millimeter of the tube before its open end. In other embodiments, the reduction in diameter at the mouth is gradual, for example in the form of a cone forming, in section, a bevel on each edge of the tube or discontinuous, in the form of more than one shoulder such as that shown in [Fig. 8].
[0048] This reduction in diameter of the tube at its mouth makes it possible to absorb the excess molten material while remaining within the outer perimeter of the generatrices of the cylindrical or conical tube.
[0049] Preferably, the induction flow is oriented so that the melting occurs preferentially on the seal facing the inner wall of the tube, the part of the seal facing the outer wall of the tube receiving a lower induction flow and therefore heating up less. Since only the seal is hot, no melting of the tube can occur outside the contact zone of the two parts. The polypropylene is therefore softer on the inner wall of the mouth of the tube and is therefore pushed towards the inside of the tube, while the outer wall of the mouth of the tube, which is more rigid, does not deform beyond the generatrices of the tube.
[0050] All of these measures make it possible to increase the contact surface between the tube and the seal for better sealing without degrading the ease of use of the seal when opening.
[0051] Finally, the use of this technology reduces space requirements and allows us to multiply the number of workstations on industrial equipment.
[0052] Figures 2 and 3 represent the diffusion of thermal energy on the surface of the cover and over time. In [Fig.3], we observe a cooling time, while the induction head remains in contact with the cover without inducing magnetic flux, higher than the induction time.
[0053] For the decoration, the container preferably includes an IML (“In Mold Labeling”) label, which allows for four-color decoration to be obtained.
[0054] Thanks to this type of label, the tube can be molded in "crystal" polypropylene, therefore without additives, which constitutes a significant qualitative advantage.
[0055] This IML label, since it is manufactured with a "barrier" support, makes it possible to solve the problem of polypropylene containers which are relatively porous.
[0056] However, in order to solve the sealing problems, the tube is relatively long (more than 100 millimeters) and narrow (less than 17 millimeters).
[0057] Preferably, a mold is used which holds the label using venturi (air suction). Since the label does not cover the entire circumference of the tube, the annular channel of this venturi must be wide enough to allow the passage of air and a sufficient suction effect, without however allowing the suction of material which would block this channel in the event of absence or lack of integrity of the label during injection. Preferably, the dimension of this channel is between 5 and 15 microns. At least two venturi suction channels are arranged on each external mold, near the ends of this mold.
[0058] Possible technical specifications for the IML label are given below: barrier material, multi-layer cast polypropylene (CPP) film (Polypropylene / Ethylene-vinyl alcohol EVOH / Polypropylene), with a thickness between 50 microns and 80 microns, for example 65 microns.
[0059] In embodiments, the method for constituting a packaging container for a preservative-free liquid comprises: - the manufacture of a synthetic material container fitted with an IML label, - the filling of this container, - the sealing of this filled container (in particular by induction and more particularly by peripheral induction) and - sterilization of the contents (particularly by autoclave).
[0060] In the manufacturing unit shown in [Fig.l], the empty tubes are loaded in bulk by an operator at the entrance to the line (on the left) and the filled tubes, sealed and stored on a support of multitudes of tubes are received by this operator at the exit (on the right). The production line comprises: - automatic feeding of empty tubes (unpicking, grouping on a motorized conveyor with suction, positioning in packaging buckets), - packaging, - sealing, - placed on a support for sterilization.
[0061] Object of the invention
[0062] The invention relates in particular to a container for liquid in the form of a polypropylene tube sealed with an aluminum film.
[0063] In embodiments: - the lid is made of coextruded aluminum with a layer of polypropylene, - the tube has, before sealing, an external shoulder near its mouth, - the tube is sealed with magnetic induction, - the magnetic induction flux is limited to the part of the cover opposite the mouth of the tube, - the magnetic induction flux is higher opposite the inner wall of the tube mouth than opposite the outer wall of the tube mouth, - once the fusion and assembly of the cover and the tube have been completed, the head induction remains under pressure on the seal until the polypropylene cools below a predetermined temperature, - the cover is air cooled, - the container has an IML label (acronym for “In Moule Labelling”), - the label is made of barrier material that does not allow oxygen to pass through its thickness, - during tube molding, the label is held in position by suction through the external mold, - the diameter of the suction channels is between 5 and 15 microns, - the label is a cast polypropylene (CPP) film, - the label is multi-layered, with two layers of polypropylene surrounding a layer of Ethylene-vinyl alcohol (EVOH), - the label has a thickness between 50 and 80 microns.
Claims
Claims
1. Container for liquid in the form of a polypropylene tube sealed with an aluminum film.
2. Container according to claim 1, in which the lid is made of aluminum coextruded with a layer of polypropylene.
3. Container according to one of claims 1 or 2, in which the tube has, before sealing, an external shoulder near its mouth.
4. Container according to one of claims 1 to 3, in which the tube is sealed with magnetic induction.
5. Container according to claim 4, in which the magnetic induction flux is limited to the part of the seal facing the mouth of the tube.
6. Container according to one of claims 4 or 5, in which the magnetic induction flux is higher facing the internal wall of the mouth of the tube than facing the external wall of the mouth of the tube.
7. Container according to one of claims 3 to 6, in which, once the fusion and assembly of the seal and the tube have been carried out, the induction head remains under pressure on the seal until the polypropylene has cooled below a predetermined temperature.
8. A container according to claim 7, wherein the seal is air cooled.
9. Container according to one of claims 1 to 8, which comprises an IML label (acronym for “In Mold Labeling”).
10. Container according to claim 9, in which the label is made of a barrier material which does not allow the passage of oxygen through its thickness.
11. A container according to either of claims 9 or 10, wherein, during molding of the tube, the label is held in position by suction through the outer mold.
12. Container according to claim 11, wherein the diameter of the suction channels is between 5 and 15 microns.