GB1601421A - Pressurised dispensing container having a collapsible inner compartment - Google Patents

Abstract

The invention is concerned with the gassing of so-called two-chamber cans. These consist of an elastic internal container (16) in a fixed external container (12). The internal container (16) is filled with a liquid or paste. The interspace (38) between the two containers is gassed with a pressure medium. According to the invention, for this purpose, the internal container (16), after being filled, closed with a cap (26) and introduced into the external container (12), is raised somewhat. An annular gap is thereby formed between the upper ends of the two containers. The pressure medium is introduced through this into the interspace (38). The internal container (16) is subsequently lowered and its upper edge connected to the external container (12) in a pressure-proof manner. <IMAGE>

Description

(54) PRESSURISED DISPENSING CONTAINER HAVING A COLLAPSIBLE INNER COMPARTMENT (71) We, RHEN BETEILIGUNGS- UND FINANzIERUNGs-AG a Company organised under the laws of Switzerland of Schwarrzhorngasse 170, Stein am Rhein, Switzerland (formerly known as Rhenag AG), do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention concerns pressurized canister dispensers for liquid and paste-like substances and methods of pressurizing such dispensers.

Receptacles of this kind are sometimes known as double-chamber canisters (usually abbreviated to cans). Unlike the simple aerosol containers in which the liquid or paste substance which is to be delivered is contained together with a propellant gas in a single chamber, in a double-chamber can the consumer product and the propellant gas are accommodated separately, each in its own compartment. The inner container forms the chamber for accommodating the consumer product and the intermediate space between the inner and the outer container forms the chamber for accommodating the propellant gas.

In a known double-chamber can described in West German Patent Specification 2,103,447, a hole is provided in the base of the outer container, which hole can be sealed with a stopper. The intermediate space between the two containers can be pressurized or filled with pressure gas via this hole. The filling of the inner container with the consumer product is effected from the top. This means that a double-chamber can of this design has to be filled with pressure gas from the bottom and with consumer product from the top.

Simple aerosol containers or single-chamber cans are filled entirely from the top. Both the consumer product and the propellant gas are put into the single-chamber can from the top. The trend is now away from the use of the single-chamber cans and towards the double-chamber cans thus rendering obsolete the filling apparatus which fills only from the top.

Existing apparatus adapted to fill from the top could of course be employed if a doublechamber can is available which can be filled with product and gas from the top. To this end a double-chamber can has been proposed in West German Patent Specification 2,628,926 which comprises a rigid, pressureresistant outer container and an inner container made of a flexible material with a neck section which is substantially rigid, but which can be elastically deformed in the radial direction. This neck section is designed to correspond with the edge of the opening of the outer container so that it sits initially on the edge of the opening when the inner container is inserted into the outer container, and thereafter can only be introduced further into the outer container by overcoming a resistance which depends on its shape and elasticity.During assembly and for filling this double-chamber can, the inner container is pushed into the outer container up to the point described, where its neck section rests on the opening edge of the outer container.

After this the inner container is filled. Next, the valve lid is placed on the inner container and attached thereto. After this, the inner container is pushed completely into the outer container by radial compression on its neck section. The valve lid thus comes to rest freely on the edge of the opening of the outer container. The propellant gas is then introduced into the intermediate space between the inner and outer containers, after which the valve lid is sealed onto the opening edge of the outer container.

The successful filling of this known can with the consumer product and the propellant gas depends to a great extent on the characteristics of the neck section of the inner container. This neck section has to sit on the curved edge of the open end of the outer container, while the inner container is being filled. In order to do this, the neck section must have a certain resistance to deformation or it would be pulled down by the weight of the consumer product which is poured into the inner container, so as to slip through the open end of the outer container.

After the inner container has been filled, however, the neck section has to be radially compressed and pushed completely into the outer container. The neck section therefore has to possess the contradictory properties of resistance to deformation and elasticity, and this means that its shape must be very carefully chosen and its wall thickness maintained within close tolerances and the plastics material used for the inner container and the neck section must be carefully selected, and must have consistent properties.

A first object is to provide a doublechamber can having an inner container in which the requirements regarding the shape, dimensional tolerances and material are very much less stringent.

A second object is to provide a method of filling the improved can.

According to a first aspect of the invention, there is provided a double chamber can for containing a liquid or paste-like substance under pressure for dispensing same, comprising a generally cylindrical outer container having an open end with an annular upper edge, an inner container for said substance, fitted within the outer container and internally spaced therefrom to define an intermediate region which can be filled with gas under pressure, said inner container having an open end with an annular upper edge adapted to mate and form a seal with the annular upper edge of the outer container, a lid for closing off the inner container, and a dispensing valve in the lid, wherein the annular upper edge of the inner container is formed at the top of a necked in region, which necked in region can be axially expanded and contracted in the axial direction in such a manner that the annular upper edges of the outer and inner containers can be relatively moved in the axial direction without displacement of the main portion of the inner container relative to the outer container, thereby to facilitate the opening and closing of an annular gap between the annular upper edges of the outer and inner containers through which gas under pressure can be admitted to said intermediate region.

According to a second aspect of the invention, there is provided a method for filling and pressurizing a canister dispenser for dispensing liquid or paste-like substances under pressure, which canister comprises a rigid outer cylindrical container with a lid in the form of a valve support, an inner container for containing the liquid or pastelike material and a dispensing valve mounted in the lid and wherein the inner container, which is open at the upper end, has a necked in region with an annular upper edge which can be clamped between an annular upper edge of the outer container and an edge of lid, said method comprising the steps of inserting the inner container into the outer container, filling the inner container with the said liquid or paste-like substance, placing on the lid, causing or allowing sufficient axial expansion of the necked in region of the inner container after the latter has been filled to form an annular gap between the annular upper edges of the inner and outer containers, pressurizing the intermediate space between the inner and outer containers with propellant gas under pressure via this annular gap, lowering the annular upper edge of the inner container by compression of the necked in region to close the annular gap and clamping the annular upper edge of the neck of the inner container between an edge of the lid and the annular upper edge of the outer container In this way both the consumer product and the propellant gas can be filled from the top end thereby allowing existing filling apparatus to be employed with very little modification.

In order to facilitate the lifting of the filled inner container, it is proposed that the lid which contains the exit valve is inserted into, and frictionally held in place in, the neck of the inner container after the latter has been filled so that both inner container and lid are lifted to allow the insertion of the propellant gas, after which the inner container still with the lid attached is lowered again and the edge of its neck is clamped to the outer container edge. Preferably the dimensions of the cylindrical section of the lid which is to be pushed into the neck of the inner container and the neck of the inner container itself must be selected so that a tight fit is formed therebetween which is such as to allow the inner container to be lifted up by pulling on the lid.

The lid, with the neck of the inner container gripped thereon, is raised by a short distance typically in the range of a few tenths of a millimetre, although in special cases it may be advantageous to raise it by up to 10 mm. The annular gap thus created is quite adequate to allow for the introduction of the propellant gas.

The filling machines previously mentioned include expanding tools by which the lid is clamped to the inner and outer container.

This is known as clinching. Since the invention is concerned with providing a can which can be filled by existing top-filling machines use can be made of the expanding tools by providing that the inner container is first inserted in the outer container, so as to rest with the curved edge of its neck on the edge of the open end of the outer container, after which the inner container is filled and then the lid is put on and pushed in, the expanding tool is applied to the lid and the latter is pushed into the neck of the inner container friction-locked, the expanding tool is expanded and lifted with lid and the neck of the inner container which is held by the latter, the intermediate space between the inner and outer containers is filled with gas, the lid and the neck of the inner container are then lowered with the expanding tool until they rest on the edge of the outer container, and the expanding tool is further operated in a known way to clamp or clinch the edges of the two containers and the lid.

After it has been filled with the consumer product, the inner container is considerably increased in weight. Depending on the shape of its cross-section, its sides may make contact with and be supported by the inner wall of the outer container. In this eventuality the inner container will resist being lifted by the lid pushed into its neck.

In order to avoid this and in order to avoid any need to lift the mass of the inner container, the invention includes an inner container for a double-chamber can in which the neck of the inner container can be expanded or contracted in the axial direction.

Preferably, the neck has concertina-like folds which are contracted when the necks of the inner and outer containers are in contact, but can expand to allow the upper end of the inner container to lift relative to the main part of the inner container which lies below the concertina-like folds and which holds the consumer product, thereby allowing the latter part to remain stationary.

In a method of constructing and filling this preferred embodiment of double-chamber cans, the inner container is inserted in the outer container when it is empty, whilst inside the outer container it is then filled (and expanded within the outer container) with the liquid or paste substance (consumer product) which the can is to dispense, it is then closed with a lid member which contains a dispensing valve.

An annular gap is formed between the upper edges of the inner and outer containers by lifting the lid and upper end of the inner container, causing the concertina-like folds to open up. The space between the inner container and the outer container is filled via the annular gap with a propellant medium, such as a gas or gaseous mixture such as air under pressure, after which the gap is closed by pushing the inner container end back into contact with the outer container and the edge of the neck is clamped to the outer container edge.

As the inner container is filled, its weight increases and it tries to slip down in the outer container. This downwards movement ends after a short time. The inner container expands radially slightly as it is filled. It presses against the inner face of the casing of the outer container. The pressure and friction forces created thereby counteract any further downwards movement by the inner container. Due to its concertina-type design, the neck of the inner container has a certain amount of elasticity. This makes it possible to raise it with the valve lid inserted in it, after the inner container has slipped down slightly during the initial part of the filling process.

This method has a disadvantage in that during initial filling the inner container slips axially down inside the outer container before it is prevented from further doing so by expansion due to the weight/mass of the consumer product therein and after being filled has to be lifted to form the annular gap through which the propellant material is to be inserted.

It may be desirable to shorten this cycle of movement and to simplify it.

According therefore to another preferred embodiment of the invention in a doublechamber can the inner container has at least one foot on which it can stand within the outer container, so that during the initial filling process, during which the weight of the inner container increases suddenly, it does not slip down inside the outer container and the upper edge of the inner container projects by an amount determined by the foot, above the edge of the outer container even after filling. Accordingly it is no longer necessary to lift up the neck of the inner container after insertion of the valve lid to introduce the gas, and then to lower it again.

In fact the operating cycle can be simplified so that after the valve lid has been inserted, it is pressed down and simultaneously the propellant gas is introduced. The timing is arranged to be such that sufficient propellant gas has been introduced by the time that the edge of the inner container comes to rest on the edge of the outer container so that immediately the edges of the valve lid, the inner container and the outer container can be clamped together in a known manner.

The foot provided according to the invention thus prevents the inner container from slipping down within, and ensures a constant amount of projection of the edge of the inner container above the edge of the outer container. This means that the cycle of movement is speeded up and simplified, and the outlay for machines is reduced.

It might be thought that the same result could be achieved by simply making the inner container longer. However, this is not generally possible, since although the shape of the inner container allows the gas to be introduced from the top, it often has to be inserted into an outer container of a kind which has a hole in its base which is usually closed by means of a bung. If the inner container were to be of sufficient length so that its lower end rested on this bung, then damage would be inevitable.

The height of the foot is preferably such that, when its neck is not being stressed, the edge of the inner container projects above the neck of the outer container by one to 10 millimetres. A gap of this size is sufficient to allow propellant gas to be inserted but is also small enough to be absorbed by collapsing the concertina-like folds of the neck of the inner container.

In general the inner container is formed by blow-moulding and typically a seam is formed around the lower end of the container. If so it is preferable to mould the foot to the container along this seam.

The invention will now be described by way of example with reference to the accompanying drawings.

Fig. 1 is a cross-section through the upper end of a double-chamber can having inner and outer containers, in which the upper end of the former is resting on the upper end of the latter to close any gap therebetween but without the lid in place, Fig. 2 is a similar view to that of Fig. 1, but in which the inner container is filled with consumer product, with the lid shown on an arm of an expander tool, prior to insertion, Fig. 3 is a similar view of a further step of a method of constructing and filling a doublechamber can, in which the lid has been pushfitted into the neck of the inner container and the two have been lifted slightly in order to admit the propellant gas.

Fig. 4 is a similar view of the completed assembly in which the lid, the upper edge of the neck and inner container and the upper edge of the outer container have been clamped together, and Fig. 5 is a cross-section view through another embodiment of the invention in which the inner container includes a foot.

Fig. 1 shows an outer container 12 with a rolled upper edge 14, having an inner container 16 fully inserted therein. Around its circumference the latter is shown to have depressions 18 extending in the axial direction necked in region of the inner container 16 constitutes a neck 20 which extends through the open end of the outer container 12 and the edge of the neck 22 rests on the rolled edge 14 of the inner container. The neck 20 has concertina-type folds 24.

Fig. 2 shows a lid 26 which contains a dispensing valve 28, and includes an edge 30 below which there is a sealing ring 32. An expanding tool is shown supporting the lid 26 above the open end of the inner container.

An arm of this tool is denoted by 34. The inner container 16 is shown filled with a liquid or paste substance 36. However, the intermediate space 38 between the two containers has not yet been filled with propellant gas under pressure.

Following on from Fig. 2, the cylindrical section of the lid 26 is pushed into the neck 20 of the inner container. At this point the expanding tool 34 is expanded slightly so that a firm fit is formed between the lid and the neck of the inner container. The neck of the inner container is axially compressed.

After this, the expanding tool 34 with the lid and the neck of the inner container locked thereto, is lifted or allowed to lift slightly, as shown in Fig. 3. The separation between the rolled edge 14 and the edge 22 of the neck of the inner container is, however, exaggerated for clarity.

Nevertheless Fig. 3 shows clearly how the folds 24 have been pulled or expanded away from each other, resulting in an extension of the inner container neck.

Pressure gas is now introduced into the intermediate space 38 in the direction of the arrow 40. When the required pressure has been reached the supply of pressure gas is interrupted, the lid 26 and neck of the inner container is lowered by lowering the tool.

The arms 34 of the expanding tool are expanded, as indicated in Fig. 4, the cylindrical part of the lid 26 is stretched radially so pressing the neck 20 of the inner container down and against the rolled edge 14, the concertina-type folds 24 move closer together and the outer edge of the lid 26 is simultaneously pressed radially inwards.

Fig. 5 shows an embodiment of the invention in which the inner container includes a foot 42. As shown the folds 24 have already partly moved closer together. The foot 42 which is provided under the lower end or base of the inner container 16, has a recess 44. This recess can accommodate an intruding bung (not shown) located in the base of the outer container 12, being an outer container of a standard type which can, under different conditions, be filled from the base.

In this embodiment an upward lifting of the neck 20 after the inner container has been filled is no longer required. After the valve lid has been pushed in, the propellant gas can be introduced immediately via the annular gap, in the direction of the arrow 40. After this the lid 26 is lowered further, the folds 24 are pressed closely together and when the end 22 of the neck of the inner container finally rests on the rolled edge 14 of the outer container the annular gap is closed and the edge 30 of the lid is clamped on and clinched in known manner.

WHAT WE CLAIM IS: 1. A double chamber can for containing

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (11)

**WARNING** start of CLMS field may overlap end of DESC **. of the inner container allows the gas to be introduced from the top, it often has to be inserted into an outer container of a kind which has a hole in its base which is usually closed by means of a bung. If the inner container were to be of sufficient length so that its lower end rested on this bung, then damage would be inevitable. The height of the foot is preferably such that, when its neck is not being stressed, the edge of the inner container projects above the neck of the outer container by one to 10 millimetres. A gap of this size is sufficient to allow propellant gas to be inserted but is also small enough to be absorbed by collapsing the concertina-like folds of the neck of the inner container. In general the inner container is formed by blow-moulding and typically a seam is formed around the lower end of the container. If so it is preferable to mould the foot to the container along this seam. The invention will now be described by way of example with reference to the accompanying drawings. Fig. 1 is a cross-section through the upper end of a double-chamber can having inner and outer containers, in which the upper end of the former is resting on the upper end of the latter to close any gap therebetween but without the lid in place, Fig. 2 is a similar view to that of Fig. 1, but in which the inner container is filled with consumer product, with the lid shown on an arm of an expander tool, prior to insertion, Fig. 3 is a similar view of a further step of a method of constructing and filling a doublechamber can, in which the lid has been pushfitted into the neck of the inner container and the two have been lifted slightly in order to admit the propellant gas. Fig. 4 is a similar view of the completed assembly in which the lid, the upper edge of the neck and inner container and the upper edge of the outer container have been clamped together, and Fig. 5 is a cross-section view through another embodiment of the invention in which the inner container includes a foot. Fig. 1 shows an outer container 12 with a rolled upper edge 14, having an inner container 16 fully inserted therein. Around its circumference the latter is shown to have depressions 18 extending in the axial direction necked in region of the inner container 16 constitutes a neck 20 which extends through the open end of the outer container 12 and the edge of the neck 22 rests on the rolled edge 14 of the inner container. The neck 20 has concertina-type folds 24. Fig. 2 shows a lid 26 which contains a dispensing valve 28, and includes an edge 30 below which there is a sealing ring 32. An expanding tool is shown supporting the lid 26 above the open end of the inner container. An arm of this tool is denoted by 34. The inner container 16 is shown filled with a liquid or paste substance 36. However, the intermediate space 38 between the two containers has not yet been filled with propellant gas under pressure. Following on from Fig. 2, the cylindrical section of the lid 26 is pushed into the neck 20 of the inner container. At this point the expanding tool 34 is expanded slightly so that a firm fit is formed between the lid and the neck of the inner container. The neck of the inner container is axially compressed. After this, the expanding tool 34 with the lid and the neck of the inner container locked thereto, is lifted or allowed to lift slightly, as shown in Fig. 3. The separation between the rolled edge 14 and the edge 22 of the neck of the inner container is, however, exaggerated for clarity. Nevertheless Fig. 3 shows clearly how the folds 24 have been pulled or expanded away from each other, resulting in an extension of the inner container neck. Pressure gas is now introduced into the intermediate space 38 in the direction of the arrow 40. When the required pressure has been reached the supply of pressure gas is interrupted, the lid 26 and neck of the inner container is lowered by lowering the tool. The arms 34 of the expanding tool are expanded, as indicated in Fig. 4, the cylindrical part of the lid 26 is stretched radially so pressing the neck 20 of the inner container down and against the rolled edge 14, the concertina-type folds 24 move closer together and the outer edge of the lid 26 is simultaneously pressed radially inwards. Fig. 5 shows an embodiment of the invention in which the inner container includes a foot 42. As shown the folds 24 have already partly moved closer together. The foot 42 which is provided under the lower end or base of the inner container 16, has a recess 44. This recess can accommodate an intruding bung (not shown) located in the base of the outer container 12, being an outer container of a standard type which can, under different conditions, be filled from the base. In this embodiment an upward lifting of the neck 20 after the inner container has been filled is no longer required. After the valve lid has been pushed in, the propellant gas can be introduced immediately via the annular gap, in the direction of the arrow 40. After this the lid 26 is lowered further, the folds 24 are pressed closely together and when the end 22 of the neck of the inner container finally rests on the rolled edge 14 of the outer container the annular gap is closed and the edge 30 of the lid is clamped on and clinched in known manner. WHAT WE CLAIM IS:

1. A double chamber can for containing

a liquid or paste-like substance under pressure for dispensing same, comprising a generally cylindrical outer container having an open end with an annular upper edge, an inner container for said substance, fitted within the outer container and internally spaced therefrom to define an intermediate region which can be filled with gas under pressure, said inner container having an open end with an annular upper edge adapted to mate and form a seal with the annular upper edge of the outer container, a lid for closing off the inner container, and a dispensing valve in the lid, wherein the annular upper edge of the inner container is formed at the top of a necked in region, which necked in region can be axially expanded and contracted in the axial direction in such a manner that the annular upper edges of the outer and inner containers can be relatively moved in the axial direction without displacement of the main portion of the inner container relative to the outer container, thereby to facilitate the opening and closing of an annular gap between the annular upper edges of the outer and inner containers through which gas under pressure can be admitted to said intermediate region.

2. A can as claimed in claim 1 wherein the necked in region has concertina-like folds.

3. A can as claimed in claim 1 further comprising at least one foot on which the inner container rests inside the outer container.

4. A can as claimed in claim 3 wherein the foot is of such a height that when the inner container is resting on the foot within the outer container, the upper end of the inner container projects above the open end of the outer container to form the said annular gap.

5. A can as claimed in claim 3 wherein the inner container includes a seam as the result of being moulded in a two-part mould and the foot is moulded to the container along this seam.

6. A method for filling and pressurizing a canister dispenser for dispensing liquid or paste-like substances under pressure, which canister comprises a rigid outer cylindrical container with a lid in the form of a valve support, an inner container for containing the liquid or paste-like material and a dispensing valve mounted in the lid and wherein the inner container, which is open at the upper end, has a necked in region with an annular upper edge which can be clamped between an annular upper edge of the outer container and an edge of the lid, said method comprising the steps of inserting the inner container into the outer container filling the inner container with the said liquid or pastelike substance, placing on the lid, causing or allowing sufficient axial expansion of the necked in region of the inner container after the latter has been filled to form an annular gap between the annular upper edges of the inner and outer containers, pressurizing the intermediate space between the inner and outer containers with propellant gas under pressure via this annular gap, lowering the annular upper edge of the inner container by compression of the necked in region to close the annular gap and clamping the annular upper edge of the neck of the inner container between an edge of the lid and the annular upper edge of the outer container.

7. A method as claimed in claim 6 wherein the lid is push-fitted into the neck of the inner container so that the lid and inner container can be lifted as one to form the said annular gap.

8. A method as claimed in claim 7 wherein the assembly of the lid, and the neck of the inner container to which the lid is attached, is raised by a distance of the order of a few tenths of a millimetre.

9. A method as claimed in claim 6 wherein the inner container neck has an outwardly turned curved edge and when inserted into the outer container this curved edge rests on the edge of the outer container, and wherein the lid is push-fitted into the neck of the inner container by the expanding tool and whilst the latter is still somewhat expanded, it is raised, simultaneously lifting the lid and the inner container which is held by it to form the said annular gap, and wherein the gap is closed by lowering the expanding tool (whilst still somewhat expanded) until the curved edge of the inner container again rests on the edge of the outer container, whereupon the expanding tool is further operated to clamp together (clinch) the edges of the containers and the lid.

10. A flexible walled container constructed and arranged substantially as herein described with reference to and as illustrated in the accompanying drawings.

11. A method of filling and pressurizing a canister according to claim 6 and as herein described with reference to and as illustrated in the accompanying drawings.