Packaging assembly with improved stackability

The present invention relates to packaging assemblies with improved stackability. The packaging assembly comprises multiple inner containers which are combined by a tight fitting outer case into the packaging assembly. The inner containers are flexible and contain a fluid and a gas filled head space. By providing the inner containers with an inside pressure above the ambient pressure, the stackability of the otherwise non or at least unreliably stackable packaging assembly is substantially improved.

FIELD OF THE INVENTION 
The present invention relates to packaging assemblies with improved 
stackability. The packaging assembly comprises multiple inner containers 
which are combined by a tight fitting outer case into the packaging 
assembly. The inner containers are flexible and contain a fluid and a gas 
filled head space. By providing the inner containers with an inside 
pressure above the ambient pressure, the stackability of the otherwise non 
or at least unreliably stackable packaging assembly is substantially 
improved. 
BACKGROUND OF THE INVENTION 
Flexible packages for fluids are widely used in the foods and household 
chemical industry. For example laminated cartons for milk, beverages, 
fluid detergents, household cleaners or fabric softeners, motor oil or 
cosmetics which often are of brick type (rectangular) or of the gable top 
type (rectangular but with gable top)are familiar and much used packages 
for fluids. They are appreciated for their light weight and a low raw 
material consumption, good handlebility by the user of the fluid and 
simple processing requirements for those commercializing fluids in such 
packages. 
The stability of such a flexible container typically must satisfy the 
highest requirements of the different usage situations of the package. The 
principle three usage situations are that at the manufacturer where the 
package is assembled and filled with fluid, the storage and distribution 
conditions (including transport and store handling) and finally at the 
user of the fluid. Out of these the storage and distribution conditions 
pose the highest requirements on a flexible container, in particular 
sufficient stackability is critical in depot storage and truck transport. 
In order to limit the material consumption but still to withstand 
essentially all storage and distribution requirements while improving at 
the same time the handling during storage and in the distribution system 
flexible containers are often combined into a packaging assembly. The 
packaging assembly can be formed by stretch or shrink wrapping several 
flexible containers together,.which improves foremost the handling of the 
packaging assembly and not so much the stability. Also the packaging 
assembly can be formed by a high strength outer case which provides the 
required strength to support stacking of several packaging assemblies and 
makes handling of the number of inner containers which are combined in the 
packaging assembly easy. 
The before mentioned advantages of the flexible container are however 
diminished when using such a high strength outer case. Therefore an 
objective of the present invention is to provide a packaging assembly 
having flexible inner containers and only requiring a low strength outer 
case. Alternative the objective of the present invention is to improve the 
stackability of a packaging assembly comprising inner containers combined 
by an outer case. 
Other objectives satisfied or improved by the present invention are reduced 
material consumption for the inner containers and the outer case; allowing 
to reduce or eliminate additional packaging support or protection items 
for the packaging assembly (corner posts, cardboard layers, stretch or 
shrink wrap); better appearance of the individual packaging assembly and 
of larger combinations of packaging assemblies. The improved packaging 
assembly further does not restrict the use as a display case. 
It is yet another independent objective of the present invention to provide 
a process allowing the manufacture of the improved packaging assembly. 
These and other objectives will become more apparent in the following 
description of the invention. 
BRIEF DESCRIPTION OF THE INVENTION 
According to the invention there is provided a packaging assembly of 
multiple identical flexible inner containers for fluids combined in a 
tight fitting outer case of generally rectangular shape. The flexible 
inner containers comprise a head space filled with gas above the fluids. 
The packaging assembly allows improved vertical stacking by an inside 
pressure in the flexible inner containers above the ambient pressure. 
The characteristics of the preferred executions of the inventions are those 
found in the dependent claims. 
According to the processing aspect of the invention to manufacture 
packaging assembly according to the invention, the following steps have to 
be conducted 
a) providing a flat carton blank for forming a lower tray part which 
constitutes the bottom and the side walls of the outer case; 
b) providing inner containers of increased inside pressure and placing them 
on the flat carton blank in the bottom area; 
c) folding up the side walls of the carton blank to form the lower tray 
part tightly around the inner containers and joining the side walls along 
their vertical edges to each other; 
d) placing a lid on top of the inner containers and joining the lid to the 
lower tray part, preferably along two opposite horizontal upper edges of 
the lower tray part at overlapping flaps which may be integral to the lid 
or to the lower tray part.

DETAILED DESCRIPTION OF THE INVENTION 
The multiple inner containers of the packaging assembly according to the 
present invention are flexible. Flexible in this context refers to 
containers which would start bulging and possibly even collapse when being 
stacked on top of each other. 
Such containers are well known in the art and are typically made of 
laminate material for which the layers of the laminate are selected from 
paper, cardboard, aluminum foil and polymeric materials. The order in 
which these materials are laminated together strongly depends on the fluid 
to be filled into these inner containers. 
In particular inner containers for liquids which easily oxidize and thereby 
deteriorate preferably have one gas tight layer for example of aluminum 
foil. Many food products like fruit juice beverages are therefore 
preferably packed into inner containers having a laminate structure which 
includes an oxygen barrier like aluminum foil. Other products such as 
household chemicals like fabric softeners, liquid detergents or liquid 
household cleaners do not require such additional precaution and can be 
packed into a simple laminate of polymeric materials and paper or 
cardboard. Those skilled in the art will easily be able to define the 
appropriate material for the inner containers. 
According to the present invention the fluids in the inner containers can 
be all those liquids mentioned already but also solid materials which 
share liquid characteristics for example fine granular materials. Typical 
examples would include granular detergents and other household cleaners. 
The shape of the inner containers should allow the rectangular outer case 
to be tightly fit round the inner containers. Usually this will require 
rectangular shaped inner containers like those known as bricks or those 
having an essentially rectangular shape but with a gable top which can be 
folded into a flat surface, without resulting in bends, creases or other 
weakening of the material. The height of the top flap of the gable top 
above the plane defined by the top edges of the inner container when 
folded down should be as small as possible, preferably less than 10 mm and 
most preferably less than 5 mm. 
The outer case material is selected from the same materials as the inner 
container but also could be a pure cardboard or corrugated cardboard 
material. Preferably some or all of the polymeric and paper or cardboard 
materials used for the inner container or for the outer case should be 
made of recycled material. 
The outer case has in the final packaging assembly to tightly fit around 
the inner containers. Tightly fitting as used herein means that there is 
essentially no empty space between the top of the inner containers and the 
outer case lid or between the side walls of the inner containers and the 
adjacent inner container or the outer case side wall. It is particularly 
preferred that the space between the top of the inner containers and the 
outer case lid or the sum of all spaces between one side wall and the 
opposing side wall plus all the spaces between inner containers from one 
side wall to the other is less than 5 mm, most preferably even less than 3 
mm. This tight fitting also prevents or reduces damages resulting from 
relative movement of inner containers to each other or to the outer case. 
The inner containers are not 100% filled with the fluid but comprises a 
head space filled with gas. Preferably the gas of the head space should be 
selected from a gas which is inert relative to the fluid in the container. 
For example for fruit juice beverages, a nitrogen or carbon dioxide gas is 
preferred over air which however can be easily used for household 
chemicals. 
The head space filled with gas has preferably a volume of 5% to 25%, of the 
volume of the fluid in the inner container. Having a volume within this 
range allows for optimal utilization of the container volume while 
providing enough head space to result in a broadly stable pressure 
difference relative to ambient pressure at 20.degree. C. by representing a 
large enough gaseous pressure buffer. 
For practical purposes, the relevant ambient pressure is taken at 
20.degree. C. when closing the inner container. The increase of the inside 
pressure of the inner container is selected such that even under 
temperature and barometric pressure changes, there remains a positive 
inside pressure difference to provide the desired strength increase and to 
improve stackability. Practically this is satisfied when the inside 
pressure is at least 1000 Pa, preferably more than 3000 Pa above the 
relevant ambient pressure. 
A particularly preferred execution of the present invention and the process 
according to the present invention, will now be explained in reference to 
the Figures. The packaging assembly (1) consists of the lower tray part 
(10). The lower tray part (10) is provided as a flat card board blank 
having a bottom portion (11), side panels (14), front and rear panels 
(15), the side panels (14) further having attachment flaps (16) and (18). 
When making the packaging assembly according to the present invention the 
inner containers (20) are placed on the bottom part (11) of the flat 
carton blank. Then the side panels (14) and the front and rear panels (15) 
are folded up to form the lower tray part (10) by being joined along 
corresponding vertical edges. In a last step to provide the packaging 
assembly according to the present invention a lid (12) is placed on top of 
the lower tray part (10) on top of the inner containers and is then fixed 
to the two opposite horizontal edges formed by flaps (16). The joining 
along edges of the outer carton preferably is provided by hot melt 
adhesives or welding. 
A particularly preferred embodiment of the packaging assembly of the 
present invention comprises a use of inner containers having a flat 
foldable gable top shown as number 22 in FIG. 2. Especially when using 
flat foldable gable top inner containers, the inner container can be 
filled under ambient pressure leaving a gas filled head space in the 
gable. When folding the gable into a flat position the pressure inside the 
inner container increases such that the requirements of the present 
invention are fulfilled. Packaging assemblies comprising such flat folded 
gable top inner containers are particularly desirable since upon folding 
up the gable top by the end user, the inside pressure of the inner 
container is released within the container itself, avoiding any possible 
danger of spilling fluid due to the overpressured inner container upon 
opening. 
EXAMPLES 
In the following example, the improved stackability of packaging assemblies 
according to the present invention is demonstrated. 
Inner containers having a gable top design similar to that of FIG. 2 which 
can be folded down to form a flat top are available from Elopak.TM., 
Lierstranda, Norway, under the designation Universal Gable Top.TM.. They 
have a gable top flap height above the plane of the top of the container 
of about 5 mm before being tightly packed into the outer case. The inner 
containers are made of a paper or cardboard laminate with polyethylene 
outer layers and possibly an additional barrier layer. The inner 
containers are filled with an uncompressable liquid detergent which 
occupies about 85% of the volume of the inner container. The gas volume of 
15% is filled with air. 
Eight of these inner containers are packed into an outer case of corrugated 
cardboard (B-flute or E-flute widely available for example from Seiffert 
GmbH, Reichenbach, Germany) to form a packaging assembly according to the 
invention. The measured inside pressure above ambient pressure at 
20.degree. C. in the inner containers when they are in the packaging 
assembly according to the invention was 3000 Pa. 
A measurement of the vertical acceptable force applied over the full top 
surface until permanent deformation occurs was taken with results 
according to the following table: 
______________________________________ 
Sample Force at permanent deformation 
______________________________________ 
1 inner container* 
200N 
8 inner containers* together 
1200N 
1 outer case* 1000N 
packaging assembly of the 
3000N 
example** 
______________________________________ 
*as described in the example 
**according to the invention 
The theoretically expected additive acceptable force just before permanent 
deformation which could be expected is 2200 N. Therefore the packaging 
assembly according to the invention provides an additional 800 N which can 
be used to increase the number of such packaging assemblies when stacking 
them on top of each other by 36%.