EP0499766B1 - Aerosol and its method of manufacture - Google Patents

Abstract

The present, double-walled container (1) for pressure-resistant cans, such as are known in the cosmetics industry, has a beaker-shaped inner container (5) and a single-piece outer container (4). The neck projection (11) of the bottle-shaped outer container (4) is provided with an inversion (13), by means of which an annular groove (14) is formed in the interior of the outer container (4) and in which groove (14) the inner container (5) is attached. The method of manufacturing such a container (1) provides for the inner container (5) to be introduced into the outer container (4) while it is still cylindrical; the outer container (4) to be tapered and formed into a bottle shape without the inner container (5) being deformed; the inner container (5) to be introduced into the groove (14) formed by the deformation and attached there. Alternatively, the part of the outer container (4) forming the groove (14) is provided with an external circumferential channel (19) and/or said part is placed against the neck projection (11) of the bottle-shaped outer container (4). <IMAGE>

Description

The present invention relates to a double-walled container for a funnel-free and pressure-resistant can, such as is used for dispensing flowable products, in particular cosmetic products, which container comprises a bottle-shaped outer container made from one piece and a compressible inner container, the compressible inner container having the shape a cup-shaped, ie has an upwardly open cylindrical or conical hollow body, and a method for producing the same.

Containers of this type are manufactured by the packaging industry and are preferably found in the cosmetics and materials industry, which is increasingly producing pressure-resistant spray cans and dispensers from them to package their liquid, pasty, cream or gel-like products. Cans in which the propellant gas is separated from the filling material are of particular importance today for various reasons. On the one hand, with such cans, the usually flammable propellant gas used in conventional aerosol cans, e.g. butane, propene, etc., cannot escape to the outside; on the other hand, such cans also allow propellant gases to be used which would chemically change the packaged products, e.g. compressed gases, especially air, nitrogen, carbon dioxide, etc.

It is therefore the endeavor of the modern packaging industry to produce pressure-resistant cans which are also safe in the long term and which are nevertheless inexpensive to manufacture.

Double-walled cans, as are known for example from US-A-4,308,973 and EP-A-017,147, consist of a container and a lid, the container essentially being a cylindrically shaped outer part with an inserted inner part and a funnel placed on these container parts, which respectively the lid. carries the valve cap. Usually the cylindrically shaped outer part, like the funnel, is made of tinplate or aluminum, while the inner part is made of aluminum or plastic. For the lid resp. Valve attachments are again made of aluminum or sheet metal. It goes without saying that a can composed in this way can only be produced and disposed of in a complex manner.

However, it has been shown that the three-part containers do not remain pressure-tight for long periods of time and their operational safety is inadequate when used for a long time. These sealing problems are of a fundamental nature and result from the construction of these containers, in which the outer container is flanged at its opening edge with the inner container and the funnel and then flanged. This type of connection of materials of different strengths cannot satisfy the increased requirements of a pressurized can of, for example, 250 ml or more, because in particular the mutual flow movement of the materials of different strength, which are forced by the flanging, leads to irregularities in the connection quality in this area leads.

It has also become known a container in which the conventional funnel and the cylindrical outer part are replaced by a one-piece outer container, and in which the inner container has a collar which rests on the rolled edge of this outer container and is only secured by a valve cover when it is clinched becomes. This construction cannot solve the above-mentioned sealing problems for the same reasons and moreover has manufacturing disadvantages. In particular, the inner container must be deformed and forced through the small container opening provided for the valve cover. There is no need to explain further here that this procedure is not only complex, but that the inner container can also be damaged.

A double-walled container has therefore also become known, in which the inner container and the outer container are pushed into one another without deformation, the two edges of which are glued together and drawn in and flanged together. The retraction, ie tapering, of the two cylindrical container parts is only possible with expensive and, in particular, failure-prone tools. The crimping of glued areas presents technical difficulties and places extraordinary demands on the process for producing such two-part containers.

A two-part container has also become known to the public, in which the funnel is replaced by a can shoulder integrally formed with the outer container. After the inner container has been inserted, a pre-shaped collar of the inner container lies precisely on the upper edge of the outer container. In order to close the filled bottom part of the can, the upper edge of the outer container is clipped with a commercially available aluminum or sheet metal valve. The simultaneous test or crimping three different materials as a long-term disadvantage. The preamble of claim 1 corresponds to this prior art.

The present invention aims to remedy this situation and to create a container of the type mentioned at the outset which does not have the deficiencies of the known containers.

In particular, a double-walled container is to be created, the usability of flameproof cans is improved compared to conventional can containers, allows cost-effective production, and shows no signs of fatigue and wear even after prolonged or repeated use, i.e. maintains its pressure-retaining properties undiminished.

According to the invention, this object is achieved with a container of the type mentioned at the outset, which has the features listed in the characterizing part of patent claim 1, and with a method according to patent claim 7.

The double-walled container according to the invention is essentially characterized by an outer container formed from one piece, the shape of which corresponds to that of an upwardly tapering vessel with a narrow opening. In the tapered area of this outer container, respectively. the neck, at least one annular indentation is provided, which projects into the interior of the outer container in such a way that the indentation, together with the outer container wall, forms an annular groove in the interior, which is open to the side of the outer container facing away from the tapering region. An essentially cup-shaped inner container is fastened in this groove.

The special design of this container means that Manufacturing a flameproof can only two parts are connected to each other; on the one hand the inner container with the outer container and on the other hand the outer container with the valve cover, with which an absolutely pressure-tight and operationally safe can can be created in a simple manner.

The advantages of the container according to the invention therefore not only relate to the operational safety and longevity of the pressure cans produced with these containers, but also particularly relate to the manufacturing aspects.

Materials which are not only pressure-resistant and gas-impermeable, but also corrosion-resistant and disposal-friendly are advantageously used for the production of these cans. Aluminum can be used for the compressible inner container, the pressure-resistant outer container as well as for the valve cover. The pressure-resistant joining of materials of the same type does not pose any difficulties for the person skilled in the art. In a preferred embodiment, an epoxy-based adhesive or a polymer modified with carboxyl groups is introduced and hardened in the groove formed by the indentation, and a suitable adhesive is selected for the material to be joined.

In a further preferred embodiment, the surface of the inner container is specially treated, in particular painted, in order to avoid chemical reactions of the inner container material with the filling material.

In particular, the chamber of the container according to the invention that holds the filling material is at least partially covered with a lacquer, plastic or another suitable protective film.

The method created for the production of the container according to the invention is characterized by the features of the present claim 7 and leads, surprisingly, to the fact that the inner container does not need to be specially pre-formed or re-formed in a complex manner and yet a reliable, two-part container is created can.

In particular, in the production of the container according to the invention, the cup-shaped inner container is inserted into the still undeformed outer container in a first process step, such that the bottom parts of these container parts lie adjacent to one another. The axial extent of the inner container is less than that of the outer container. The part of the outer container which projects over the inner container used in this way is then deformed according to the invention in a second method step without deforming the inner container in the process. In a third process step, the upper edge of the inner container is pushed into the groove created by the inventive deformation of the outer container and fastened there, in particular glued.

In a preferred embodiment, the part of the outer container forming the groove is additionally deformed and is placed against the tapering part of the outer container.

In the alternative, the part of the outer container forming the groove can be provided with an outer circumferential groove, in particular in order to additionally secure the inner container.

In a development of the method according to the invention, the inner container which comes into contact with the filling material is at least partially coated with a suitable protective film. This coating makes it possible to make the container according to the invention also suitable for technical fluids, such as silicone sealing compounds or lubricants, and for products from the food and pharmaceutical industries.

Further preferred features of the invention result from the present claims.

The invention is to be explained in more detail below with the aid of a special exemplary embodiment and with the aid of the figures.

• Figur 1 einen Querschnitt durch ein bekanntes dreiteiliges Dosenunterteil;
• Figur 2 einen Querschnitt durch ein bekanntes zweiteiliges Dosenunterteil;
• Figur 3 einen Querschnitt durch einen erfindungsgemässen Behälter;
• Figuren 4a-d verschiedene Ausführungsformen des erfindungsgemäss verformten Behälters;
• Figur 5 eine schematische Darstellung des Verfahrens zur Herstellung des erfindungsgemässen Behälters.

Show it:

• 1 shows a cross section through a known three-part can bottom part;
• Figure 2 shows a cross section through a known two-part can bottom part;
• FIG. 3 shows a cross section through a container according to the invention;
• Figures 4a-d different embodiments of the container deformed according to the invention;
• Figure 5 is a schematic representation of the method for producing the container according to the invention.

The three-part container 1 of known type shown in FIG. 1 comprises a double-walled container 2 and a funnel 3, which double-walled container 2 essentially consists of an outer container 4 and an inner container 5. The outer container 4 is made of pure aluminum and drawn into a cylindrical shape, i.e. is seamless. The upper edge of the container is designed as a flange in order to be flanged and flanged with the inner container 5 and the funnel 3. The bottom 7 of the outer container 4 is curved inwards and provided with a bottom hole 9 provided for receiving a stopper 8. The inner container 5 placed in the outer container 4 is also made of pure aluminum and is e.g. brought into a foldable form by soft annealing. The attachment takes place in the flange 6 between the outer container 4 and the funnel 3. This funnel 3 is usually made of tinplate, and exceptionally also of aluminum. The container 1 constructed in this way is capped with a prefabricated valve piece after the product to be packaged has been filled in, in that the valve plate is clipped to the funnel opening. A desired pressure medium is introduced in the space 10 between the outer container 4 and the inner bag 5 and held therein with the stopper 8.

FIG. 2 shows a two-part container 1 known to the public, in which the funnel 3 passes through a can shoulder 11 integrally molded with the outer container 4 is replaced. In this container 1, the inner container 5 is made of a flexible plastic, for example of a suitable polyethylene, in order to make it possible to insert this inner container 5 at all without significant injuries. After the inner container 5 has been inserted, a pre-shaped collar 12 of the inner container 5 lies precisely on the upper edge of the outer container 4. In order to close the filled lower part 1 of the can, the upper edge of the outer container 4 is clipped with a commercially available aluminum or sheet metal valve. In this case, it turns out that concurrently reclinchen or. crimping three different materials as a long-term disadvantage.

FIG. 3 shows a container 1 according to the invention, in which the funnel 3 is replaced by a corresponding shape of the outer container 4. The container 1 according to the invention thus comprises only two components, namely a specially shaped outer container 4 and an inner container 5. The deformation of the outer container 4 is such that an annular indentation 13 lies in the area of the neck of the bottle-shaped outer container 4. This indentation 13 is directed such that an annular groove 14 is formed in the interior of the outer container 4. The upper edge of the inner container 5 is fastened in this groove 14. It goes without saying that any suitable adhesive can be used for fastening and this can be cured in a controlled manner at most by means of high frequency, heat supply or the like. In particular, it is within the skill of the art to provide other fastening means, in particular further deformations of the groove, and to adapt the manufacturing process accordingly.

In a preferred embodiment, both the outer container 4 and the compressible inner container 5 are made of aluminum and an epoxy-based adhesive is used for their mutual fastening. Such adhesives are well known to the person skilled in the art and need not be explained further here. In this preferred embodiment, the outer container has an inwardly curved bottom 7. An opening 9 provided in this bottom 7 serves to introduce the desired pressure medium into the space 10 formed by the inner container 5 and the outer container 4. This pressure medium should be able to exert a pressure of up to 21 bar without the outer container 4 leaking. In the preferred embodiment, the inner container 5 consists of soft aluminum, as is known today as tube material, and can be additionally treated in the desired manner for certain purposes. For example, this container can be provided with a protective covering 15, as is described in detail in EP-A-418 724, so that no chemical reaction can take place with the contents. It goes without saying that the inner container 5 itself can also be made from a product-compatible plastic.

In a further development of the container according to the invention, the cup-shaped inner container 5 is somewhat expanded in its opening area and even has a rolled rim. The inner container 5 can thus be spaced apart from the outer container and can be fastened even more securely in the groove 14. By spacing the two container parts from one another, the ratio between the volume of the intermediate space 10 and the volume of the inner container 5 can be changed in a simple manner, i.e. can be adapted to the wishes of the can manufacturer. Cans in use today have a volume ratio of 36:64.

FIGS. 4a-d show possible additional deformations of the part of the container 1 according to the invention which forms the groove 14. As shown in FIG. 4a, this can rest against the tapering part of the outer container 4 or have a circumferential groove 19, such as that shown in the figure 4b is shown. It is understood that an O-ring 16 can also be inserted into the groove 14 for better fixation and stabilization and / or the wall thickness of the container parts to be connected is increased at least in this area.

FIG. 5 schematically shows the essential process steps for the production of a container according to the invention. Starting from a first cylindrical container 4 and a second cup-shaped container 5, the second container 5 is inserted into the first container 4 in the present method. The geometric dimensions of the two containers 4, 5 are matched to one another and normally correspond to the masses of commercially available cans, i.e. 170mm height at 40mm diameter for 125ml cans, respectively. 200mm height at 50mm diameter for 255ml cans. It is important, however, that the axial extent of the inner container 5 is at least so much smaller than that of the outer container 4 that the outer container 4 can be deformed in a second process step without deforming the inner container 5. In the preferred embodiment, this difference in length is approximately 20 mm. For the third method step, the inner container 5 is pushed against the opening until its edge lies in the groove 14 and is somewhat jammed there. In the alternative, a circumferential groove 19 is now formed in the part of the outer container 4 forming the groove 14 from the outside, such that the inner edge of the inner container 5 can no longer slide out of the groove 14. A suitable adhesive 18 is introduced into this groove 14 for final fastening. It has proven to be particularly advantageous to allow easy-flowing adhesive, in particular an adhesive with a viscosity of 500 poise, to flow into the groove 14 through the opening 9 in the bottom 7 of the outer container 4 via the slightly convex bottom of the inner container 5 until the groove 14 is filled with it. However, it goes without saying that the adhesive can also be introduced through the valve-side opening of the outer container and applied there before the inner container 5 is brought into the groove 14.

The advantages of the manufacturing process described are immediately apparent. In particular, the inner container 5 does not need to be subjected to any further deformation and the outer container 4 no longer needs an additional one Funnel 3 to be connected. The user is free to attach another protective covering 15, as described for example in EP-A-418'724, in the chamber 17 which comes into contact with the filling material.

It goes without saying that the present invention is not limited to the above exemplary embodiment, but rather that further modifications in the design of the outer container 4, in particular for the mutual fastening of the containers 4, 5, are within the range of the skilled person. For example, the groove 14 can be stiffened further, or any coatings can be applied in order to equip the container to be product-compatible. In particular, the use of components made of the same material avoids all undesirable metallic effects that occur with commercially available cans.

The containers according to the invention are thus characterized by an inexpensive production method and high long-term stability, i.e. Security off.

Claims (11)

1. Double-walled container (1) for a funnel-free and pressure-tight can, as is used for dispensing flowable products, in particular cosmetic products,
   said container (1) comprising a flask-shaped outer container of one-piece construction (4), and a compressible inner container (5), having a cup-shaped, i.e. an upwardly open cylindrical or conical hollow body, characterized in that
   the bottle-shaped outer container (4) comprises an annular indentation (13) in the vicinity of its neck area (11), and
   said inner container (5) being secured at its upper rim in an annular groove (14) being formed inside said outer container by said annular indentation (13).
2. Double-walled container (1) according to claim 1, characterized in that special fixing means, especially an adhesive product on an epoxy basis (18), are provided for fixing said inner container (5) in the groove (14).
3. Double-walled container (1) according to claim 2, characterized in that the wall thickness of the outer container (4) and/or the inner container (5) is increased at least in the area of their being fastened together.
4. Double-walled container (1) according to claim 2, characterized in that the upper rim of the inner container (5) is beaded.
5. Double-walled container (1) according to claim 2, characterized in that the chamber (17) receiving the filler material is at least partially coated with a protective coating (15).
6. Double-walled container (1) according to claim 2, characterized in that the portion of the outer container (4) forming the annular groove (14) comprises a peripheral, circumferential indentation (19).
7. Method for manufacturing a double-walled container according to claim 1, characterized in that, after the step of manufacturing an upwardly open, preferentially cylindrical first container, a second, cup-shaped container is introduced into said first container, the axial expansion of said second container being at least that much smaller than the axial expansion of the outer container (4), so that the outer container (4) can, in a second method step, be shaped without deforming the inner container (5),
   said first container is shaped, at least in the area of its opening, into a flask-shaped outer container (4), without deforming the therein positioned second container,
   the outer container (4) is shaped such, that at least one annular indentation (13) is shaped in the tapering region of the flask-shaped outer container (4), said annular indentation (13) projecting into the inner region of the outer container (4) such, that the annular indentation (13), together with the unformed walls of the outer container (4) form an annular groove (14), which is open towards the side opposite the tapering region of the flask-shaped outer container (4), said second container is positioned such, that its upper rim lies inside said annular groove (14) and is secured there by adhesive means (18).
8. Method according to claim 7, characterized in that the portion of the outer container (4) which forms the annular groove (14) is additionally shaped, in particular is pressingly deformed and/or is provided with a peripheral, circumferential indentation (19).
9. Method according to claim 7, characterized in that a very fluid adhesive is utilized as adhesive (18), which is introduced through the opening (9) in the base (7) of the outer container (4) and which fills the annular groove (14).
10. Method according to claim 7, characterized in that at least those parts of the container coming into contact with the filler material are post-treated, and in particular receive a protective coating (15).
11. Usage of a double-walled container according to claim 1 for the manufacture of funnel-free cans, and in particular for cans which are suitable for technical fluids or products of the foodstuff and pharmaceutical industry.

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