GB2410237A - Double walled containers - Google Patents

Abstract

A beverage container comprises a metallic outer container (2), a plastics inner container (5) within the outer container and providing an internal space for containing a beverage, the walls of the inner (5) container substantially thermally isolating the internal space from the outer can, and a lid (8) closing the interior space of the inner container, the lid (8) being openable or having an opening means such as a ring pull formed therein for allowing the release of a beverage contained in the inner space. The inner container (5) may be a separate element inserted into the outer container or the outer container may be formed as a coating on the inner container using a metallic paint or power. The inner container may be of double walled construction, preferably with an at least partially evacuated space between the walls.

Description

241 0237 Containers The present relation relates to containers, and in

particular, though not necessarily, to containers for tizzy or carbonated beverages.

Consumers are used to purchasing ready-made drinks in either metallic, glass, or plastic containers. Metallic containers are typically of the "can" type having an open only mechanism such as a ring-pull, whilst glass and plastic containers are typically in the form of a bottle with a screw on lid. Of the various materials, metal might be considered the most preferred, firstly because it gives the drinker the best perceived taste, secondly because the materials used are generally recyclable, and thirdly because metallic containers are in practice unbreakable. Glass might be considered the second choice material because it is both recyclable and gives a good taste sensation with, with the disadvantage that glass containers are breakable, whilst plastics might be considered the third choice material because of the poor taste quality which it provides.

A problem with a standard beverage container is that, after removal from a cold storage environment, the temperature of the liquid within the container starts to rise due to heat transfer with the external environment. In the case of most soft drinks, this is undesirable. The problem is particularly acute in the case of metallic containers as the metal walls conduct heat rapidly into the interior space.

It is an object of the present invention to overcome the disadvantages of existing liquid containers as outlined in the previous paragraphs.

According to a first aspect of the present invention there is provided a beverage container comprising: a metallic outer container; a plastics inner container provided within the outer container and providing an internal space for containing a beverage, the walls of the inner container substantially thermally isolating the internal space from the outer can; and a lid closing the interior space of the inner container, the lid being openable or having an opening means formed therein for allowing the release of a beverage contained in the inner space.

Preferably, the inner container is formed as a separate element from the outer container, the inner container being inserted inside the outer container. Alternatively, the outer container may be provided as a coating on an exterior surface of the inner container, for example by coating the exterior surface with a metallic paint or by use of a metallic powder.

Preferably, the plastics inner container has a shape conforming substantially to that of the outer container, e.g. both the inner and outer containers being substantially cylindrical. More preferably, the size of the inner container is such that the outer surface of the inner container forms a tight fit with the inner surface of the outer container. Alternatively, spacers may be provided around the outer surface of the inner container so as to engage the inner surface of the outer container and fix the inner container relative to the outer container.

Preferably, the inner container is formed by a moulding process, more preferably by a blow moulding process.

Preferably, the outer container is formed by a process similar to that used to manufacture conventional beverage can bodies. One such process is known as "drawing and ironing". Indeed, the outer container may be of substantially identical construction to conventional beverage can bodies.

Preferably, the inner container is of double wall construction, the walls being spaced apart. The space may be maintained by spacers such as ribs or dimples. The space is closed, being filled with air or another gas/gas mixture, or, more preferably, being evacuated or partially evacuated, in order to improve the thermal isolation of the inner space.

Means may be provided in the inner container for allowing liquid to enter the gas filled or evacuated space between the double walls, when the can is opened and the internal pressure released. For example, a valve could be provided in the innermost wall arranged to conduct fluid when the internal pressure falls below a given pressure.

Alternatively, means could be provided which ruptures when the pressure falls below a given pressure, allowing fluid to enter the space. An advantage of this arrangement is that the liquid entering the space will quickly cool the outer metallic container, allowing the drinker to sense the cool liquid contents. This may be desirable from the drinker's point of view.

Preferably, both the outer and inner containers have respective bases which are continuous with their cylindrical sidewalls. In the case of the double walled inner container, the base is also double walled. The inner and outer container bases may be substantially planar, in contrast to the domed shape of conventional can bases.

However, ridges or other projections may be provided at least on the outer surface of the outer can base to reduce contact between the base and a surface on which it is standing, thereby reducing heat transfer through the base.

Preferably, the lid of the beverage container is metallic, being substantially permanently affixed to the outer container so that it cannot be removed in normal use.

The lid may be substantially identical to conventional beverage can lids.

Preferably, the beverage container is arranged to prevent the ingress of liquid into any space existing between the plastics inner container and the outer container.

The lid may be fixed to the outer container by means of gluing, welding, pressure sealing, a combination of these means, or any other suitable means.

Preferably, the lid is provided with an opening means in the form of a ring-pull type mechanism or other frangible opening mechanism.

According to a second aspect of the present invention there is provided a method of manufacturing a beverage container, the method comprising: forming a metallic outer container having a base and side walls and being open at one end; forming a plastics inner container of substantially the same shape as the outer container; inserting the inner container into the outer container; and fixing a lid to the open end of the outer container so as to seal the internal space provided by the inner container.

A step of filling the inner space of the inner container with a beverage is preferably carried out prior to fixing the lid, but preferably after insertion of the inner container into the outer container.

According to a third aspect of the present invention there is provided a method of manufacturing a beverage container, the method comprising: forming a plastics inner container having a base, sidewalls and an open end, the sidewalls being of double walled construction with an isolated space provided 1 5 therebetween; coating an outer exterior surface of the inner container with a metallic or glass coating; and affixing a lid to the open end of the inner container so as to close the inner space defined within the container.

According to a fourth aspect of the present invention there is provided a beverage container comprising: an inner container of double walled construction and formed substantially of plastics, an isolated space being provided between the double walls so as to thermally insulate the contents of the container; an opening mechanism provided at or in one end of the plastics container; and a metallic or glass coating or covering provided around a portion of the inner container adjacent to the opening mechanism, wherein, during drinking of a contents of the container, the metallic or glass coating or covering contacts the lips and tongue of the drinker.

For a better understanding of the present invention and in order to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which: Figure I is a vertical cross-sectional view of a beverage container when in an upright position; Figure 2 is horizontal cross-sectional view of the beverage container of Figure 1; Figure 3 illustrates a vertical cross-sectional view of a neck portion of a beverage container according to a first embodiment of the invention; and Figure 4 illustrates a vertical crosssectional view of a neck portion of a beverage container according to a second embodiment of the invention.

A beverage container 1 is illustrated in Figure 1 and is formed from three major components. A first of these is a substantially cylindrical metallic outer container 2 (e.g. formed of aluminium, steel, etc), having one end closed by an integrally formed base and the other end open, which may be substantially identical to the body portion of a convention beverage can. Such can bodies are well known, as are their manufacturing techniques (e.g. drawing and ironing). The only difference of note here is the shape of the base 3 of the outer container 2. The base of a conventional can body is a concave dome, shaped to withstand the internal pressure produced by a carbonated drink. Due to the use of a plastics inserted (to be described), the base of the outer container can be substantially flat, allowing the internal space of the beverage container to be maximised.

The second major component of the beverage container is the inner container 5. This forms a plastics insert (e.g. of polypropylene, PTFE, etc) which is inserted into the outer container 2 during the manufacturing process. The overall shape of the inner container 5 is substantially identical to that of the outer container, having one end open and the other end closed by a base. However, the inner container is doubled walled as shown in Figure 1 and also Figure 2, with the walls 6,7 being spaced apart by 1-2mm except around the upper opening where the walls are sealed together. The space 4 may be maintained by suitable arranged spacers. During the manufacture of the inner container, a vacuum is pulled in the space between the two walls 6,7. The manufacturing process is typically a moulding process such as a blow moulding process.

The inner container 5 is inserted into the outer container, with the dimensions of both being such that a compression or interference fit is formed between the two, preventing relative movement of the two components providing limited space for the ingress of fluid from the interior space (after filling of the container, se below). The gap between the containers 2,5 apparent in Figures is for illustrative purposes only.

The container in this state is typically provided to the "bottler" who fills the container (up to or close to the top of the inner container 5) with the chosen beverage. If necessary, this step is carrier out under pressure. A metallic lid 8 of generally circular shape with a downturned outer rim, which again is of substantially conventional construction having a frangible ring-pull type opening mechanism formed therein, is placed over the open end of the outer container 2 and is fixed thereto to close the container. The lid 8 is typically fixed using an adhesive whilst applying a compression force around the outer rim of the lid. The step of fixing the lid must be carried out under pressure if the beverage is pressurised.

Preferably, the inner container 5 extends above the point at which the lid 8 is sealed to the outer container 2. This is advantageous as it will maximise the thermal insulation provided to the container contents. This is illustrated in Figure 3, where the outer container is identified as "A", the outer wall of the inner container by "B", and the inner wall of the inner container by "C". However, the inner container 5 may stop beneath the "necking" joint if that is desirable from a manufacture point of view. This embodiment is illustrated in Figure 4.

The inner container 5 is formed from a rigid or semi-rigid plastics material. As such, it adds a significant degree of strength to the beverage container. A significant advantage of this feature is that the walls of the outer container 2 can be made thinner than those of conventional beverage cans, given that they no longer have to withstand the same internal pressure. This results in a cost saving for manufacturers, given that the cost of the inner plastics container may be significantly less than that of the outer container. In addition, because plastic is significantly lighter than metal, the total weight of the new container design may be less than that of the conventional metal can.

It will be appreciated that the insertion of the outer container 5 into the outer container 2 reduces the internal space available for containing a beverage. However, the effect of this can be mitigated by the flat bases of the containers, in contrast to the concave dome shaped bases of conventional cans.

As is illustrated in Figures 1 and 2, a groove 9 may be formed axially along the lengths of each of the walls of the inner container 5. This groove provides a channel along which air may flow as the inner container 5 is pushed into the outer container, thus easing the insertion process and avoiding damage due to a pressure build-up.

The insulation of the contents of the beverage container 1 will be most effective when the container is only filled with liquid up to a level no higher than the top of the inner container 5. The air in the gap above will, when cooled, provide an insulating layer between the contents and the lid, thereby reducing the rate of heat transfer by conduction in a region which might otherwise heat up more quickly.

A visual indicator may be provided on the side of the container to provide a measurement indicative of the temperature of the contents of the container, e.g. thermally activated paint being applied to at least one region of the wall of the container. The temperature indicator can be constructed from materials such as a liquid crystal, in which case a layer of the liquid crystal material is applied to the external wall of the container. The visual indication might be red when the temperature of the contents is above 25 degrees Celsius, and blue when the temperature of the contents is below 12 degrees Celsius. These temperature values will vary according to the desired temperature range of the contents of the container.

A temperature indicator provides a quantitative measure of the temperature, rather than having to rely on a qualitative tactile reading.

The temperature indicator may be designed to be incorporated into a word, for example "WARM", red in colour when the contents are above a first threshold temperature, and "COLD", blue in colour when the contents are below a second, lower, threshold temperature. The indicator may alternatively be a temperature scale, with a mark indicating the temperature of the contents on the scale, in a similar manner to a thermometer. The indicator can be incorporated into a manufacturer's logo or other similar design on the outer wall of the container.

It is appreciated that the external wall of the container is not in direct thermal contact with the contents and correspondingly the temperature indicator is designed with a time lag, calculated according to the known thermal characteristics of the contents of the container. Upon removal from a cold storage device, the external wall of the container will approach ambient temperature at a faster rate than the contents due to the vacuum insulation of the contents. The temperature indicator is designed to produce a measurement of the temperature of the contents of the container based upon the temperature of the external wall of the container, the thermal transfer characteristics of the container, and the specific heat capacity of the contents of the 1 5 container.

Known liquid containers removed from a cold storage device can only retain their lowered temperature if stored in thermal boxes or other devices specifically designed to shield their contents from the external thermal environment, e.g. polystyrene can holders. Using a container according to the present invention, a liquid container may be stored in a cold storage device, removed, and the contents used (in the case of a beverage, be consumed) at a later time whilst retaining its cold temperature.

Furthermore, the container may be constructed to the same dimensions as existing containers, thereby requiring no redesign of the external appearance of the container, or to cooperating devices, e.g. vending machines.

In addition to these advantages, the container can be made to look substantially identical to the conventional metallic beverage can. This will reduce consumer resistance to the introduction of a new product. Yet another advantage is that the feel of the container will be similar to the conventional container, and will present the drinker with the pleasant metal on tongue and lip sensation which, as mentioned above, is preferable to the taste and feel of plastic.

A container according to the present invention provides a convenient way of maintaining liquids at a low temperature for a long period of time without the need for separate thermal insulation. In addition, the combination of metal outer and plastics inner should provide an environmentally friendly can which can be recycled.

It will be appreciated by the person skilled in the art that various modifications may be made to the above embodiments without departing from the scope of the present invention. In one modification, a gap or hole is provided in the outer container 2 such that the inner container 5 can be viewed through the gap or hole. This may be desirable for example to allow the user to see the structure of the can and/or to provide a visually interesting advertisement. In yet another modification, the metallic outer container may be replaced by a glass container.

Claims (6)

1. Claims: 1. A beverage container comprising: a metallic outer container; a

   plastics inner container provided within the outer container and providing an internal space for containing a beverage, the walls of the inner container substantially thermally isolating the internal space from the outer can; and a lid closing the interior space of the inner container, the lid being openable or having an opening means formed therein for allowing the release of a beverage contained in the inner space.
2. 2. A container according to claim 1, the inner container being formed as a separate element from the outer container, the inner container being inserted inside the outer container.
3. 3. A container according to claim 2, the outer container being provided as a coating on an exterior surface of the inner container, for example by coating the exterior surface with a metallic paint or by use of a metallic powder.
4. 4. A container according to any one of claims 1 to 3, wherein the lid is substantially permanently fixed to the outer and/or inner container and has a frangible opening mechanism provided therein.
5. 5. A container according to any one of the preceding claims, wherein the inner container is of double wall construction, the walls being spaced apart.
6. 6. A container according to claim 5, wherein the space between the double walls is isolated and at least partially evacuated.