Note: Descriptions are shown in the official language in which they were submitted.
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INSULATED TRANSPORT CONTAINER
Field of the Invention
This invention relates to the packaging of fresh foodstuffs for transportation
in
insulated containers to minimise heat gain to the contents. It is particularly
concerned with the transport of foodstuffs cooled with ice.
Background to the invention
There is a trend toward consumers preferring to buy fresh unprocessed food.
io Difficulty is encountered when the transportation times from the point of
harvest to
the final retail outlet are more than a day and where transportation involves
a
number of loading and unloading steps. This degree of handling and can lead to
delays and if the temperature of the product varies as well the quality of the
product
will deteriorate more rapidly.
~ s Freezing of foodstuffs aids in long term preservation and transportation
but does
cause a loss of flavour. The optimum transportation method is to use
refrigerated
transport and ensure that the products are maintained at a temperature below 4
°
C. Often ice is included with the fresh produce to achieve this temperature.
To
prevent heat gain insulated containers are generally employed. These
containers
2o usually need to meet a range of parameters such as cost, robustness,
minimal wall
thickness, to minimise storage space loss, and low weight.
Many attempts have been made to design suitable insulated containers. French
patent 2697809 discloses a stackable container for transporting fish with a
product
_ basket insert which leaves an insulating air space between the external box
and
2s the internal basket. Japanese patent 6-32379 discloses an externally ribbed
container that can be sheathed to once again provide an insulating air space.
Japanese patent 8-53166 discloses a hollow walled container while USA patent
4896790 discloses a foldable thermo-box of plastic insulating material for use
in
transporting fish and meat. USA patent 5102004 discloses a foldable chill box
3o wherein the insulating walls are of polyurethane foam with foil surfaces.
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Flexible insulating containers such as bags have also been proposed. USA
patent
4211267 discloses an insulating and shock absorbing bag formed of a laminate
including a foam layer, a foil layer, polyethylene layer and optionally a
cotton layer.
GB patent 2085401 discloses a double wall bag having air or gas in the wall
cavity
and a foil layer in the outer wall.
All of these proposals address some of the requirements but many fail because
of
cost considerations, the container is too heavy or its wall thickness means it
takes
up too great a volume in the limited space available during transport.
It is an object of this invention to provide an insulated container that has
good
~o insulation performance without taking up excessive volume, or weighing too
much
in comparison to its contents.
Brief Description of the invention
To this end the present invention provides an insulated package combination
which
includes a product container having a reflective outer surface, said container
being
is disposed within a transport container having internal protrusions on its
bottom and
sides to create an air space between the reflective outer surface of the
product
container and the transport container walls.
By providing an air space between the walls of the rigid transport container
and the
product container and incorporating a reflective surface on the outer surface
of the
Zo product container, the insulating performance is enhanced without
significant
change to the packaging wall space or packaging weight.
In another aspect the present invention provides a method of transporting
chilled
food stuffs comprising the steps of
a) placing the chilled product into a product container having an outer
reflective
is surface
b) placing said product container into a transport container which
incorporates
protrusions in the base and sides to create an air space between the walls
of the transport container and the reflective surface of the product container
c) placing sufficient coolant in either the product container or the transport
3o container to maintain the product in a chilled state
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d) transporting the filled transport container to its destination before all
the
coolant has undergone a phase transition [e.g. - melted].
The produce which most benefits from the present invention are pharmaceuticals
and higher value fresh foods, which are subjected to extended travel and
storage.
s All seafoods including lobsters, crayfish, oysters, fish such as salmon,
fresh cut
flowers, fresh herbs, vegetables such as broccoli, cauliflower, lettuce,
spinach,
carrots, brussel-sprouts and fruits that benefit from chilled storage and
transportation including tomatoes, stone fruits, melons, grapes, mangoes,
strawberries, pears) bananas and kiwifruit.
io The product container may conveniently be a flexible bag of reflective
foil. For
applications where the product container needs to be liquid tight a laminate
of a
polymeric film and a reflective layer is used to form the product bag. The
function
of the protrusions on the inner wall of the rigid transport container is to
prevent the
inner product container from contacting the greater portion of the wall
surface so
~s that an air space is formed between the outer surface of the product
container and
the inner surface of the lidded container. The protrusions may be a series of
upstanding ribs or baffles arranged on the base and the side and end walls of
the
transport container. These can be aligned horizontally, vertically or both,
although
in moulded containers a vertical orientation is easier to form. The height of
the ribs
2o from the base or wails is preferably in the range of 1 to 3 cm. Below 1 cm
the air
gap provides insufficient insulating performance while above 3 cm the loss of
useable interior volume affects economic performance of the package. The
spacing between the ribs should be at least 1 cm and the upper limit will vary
according to the dimensions of the product bag and whether portions of it can
enter
2s the air space. Baffles or ribs can be provided on the lid but, as there is
usually an
air gap between the product container and the lid, these baffles are generally
superfluous.
The material of the transport container can be any suitable insulating
material such
as wood, moulded plastic such as polystyrene, plastic foams such as expanded
3o polystyrene [EPS]) or polyurethane, corrugated cardboard or combinations of
these. The baffles need not be formed of the same material as the container.
Polystyrene foam or cork baffles arranged horizontally and/or vertically on
the
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walls of a corrugated cardboard box are examples. The air space could also be
created by an open sided honeycomb structure of cardboard or plastic.
Cardboard
strips of 1 to 3 cm in width interlocking at right angles can be inserted on
the
bottom and sides to provide air spaces of 1 to 3 cm in depth. The advantage of
s using such a cardboard grid is that the thickness of the board does not
reduce the
volume of the airspace which can be a problem with cork or polystyrene ribs or
projections.
It is preferred that the lidded transport container is enclosed within a
shipping
cover which also provides insulation. This cover may be foil covered.
io The product container may be rigid but is preferably flexible. Conveniently
the
product container is a foil coated bag made from a foil laminate such as
reflective
aluminium/polyethylene. For non-water proof applications only foil need be
used.
An alternative to a foil~lm laminate is metallised polymeric film suitable for
packaging such as metallised polyethylene, polyester,or polypropylene. Inside
the
i s product container there may be a product tray or other ancillary packaging
materials used for the particular product. The product container may be vacuum
evacuated and sealed.
Coolant ,preferably water ice, is also included inside the product container
or the
transport container. The coolant must be present in sufficient quantity and at
an
2o initial temperature which ensures that it is not completely melted before
the
produce is ready for presentation. Preferably the coolant is present in an
amount
from 10% to 40% by weight of the produce. Alternative coolants to 1 to -2
°C ice
are
~ low temperature freshwater/saltwater ice[-20 to -30 °C]
2s ~ Frozen aqueous glycol mixtures
~ Frozen hydrated polyacrylamide gel packs such as that sold as "TECHNI-ICE"
~ Dry ice [solid carbon dioxide]
~ Liquid Nitrogen
If the ice or coolant is in contact with the fish or other produce it is
preferably at a
3o temperature above that at which the produce itself becomes frozen to
prevent
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undesirable tissue damage. For fish, and in particular, salmon the ice is
preferably
added at a temperature of -2 to -5°C. An alternative is to store the
coolant in a
compartment above the produce so that much lower coolant temperatures can be
used. Thus the coolant can be arranged on the internal face of the lid or on a
stand
s to elevate it above the produce within the product bag. For fish the melted
ice
flowing over the surface of the fish is a desirable flushing action
particularly
favoured in some countries such as Japan. For this reason the coolant is
preferably
stored within the product bag.
Detailed Description of the Invention
io A preferred embodiment of the invention designed for use with fish will now
be
described with reference to the drawings in which;
figure 1 is a schematic exploded end view of the package of this invention;
figures 2 and 3 are a plan view and a side view of the longer wall of the
lidded
container.
1 s Referring to figure 1 the package consists of an outer cover 1, a lidded
container 4
and a product bag 3. The external cover 1 is a foil coated 1.5mm fluted
cardboard
cover dimensioned to fit over the container 4. The container 4 is of
polystyrene with
a polystyrene lid 2. The base and walls of the container 4 include internal
baffles 5
which are 10mm in depth to create the 10mm deep air spaces 6 in the container
2o walls and base.
The product bag 3 is a polyethylene/aluminium foil laminate with an outer
reflective
surface which abuts the air spaces 6 when it is full. Alternatively a
metallised
polypropylene film with the outer surface being reflective can be used. For
transporting fish the product bag includes a drainage tray 7 and an absorbent
pad
2s 8 to absorb melted ice and fluids. The fish is placed on the tray and a
quantity of
ice is placed on the fish and the bag is then closed. The flushing action of
the
melted ice flowing over the surtace of the fish enhances its appearance.
In figures 2 and 3 a variation of the lidded container is shown. It consists
of side
walls 11,end walls12 and base 13 each of 2cm thick polystyrene. The lid 17 is
also
30 2cm thick. Baffles 14 are vertically arrayed on the side walls 71 and end
walls 12
and these extend the full height of these walls. The baffles 14 are 1 cm
square in
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end section and are spaced at least 2cm apart. Baffles 15 on the base 13 are
similarly dimensioned and spaced apart. This means that air spaces 16, which
are
1 cm deep and at least 2cm wide, surround the product bag on 3 sides. The
product
bag is dimensioned so that when it is full there is at least a 1 cm air space
between
s it and the lid 17.
It is important that, relative to the mass of the full product bag, the
baffles not be
easily compressed so that the air space is not diminished during
transportation.
Comparative Examples
The insulation performance of a package can be measured by its R value which
is
to a measure of the heat transfer through the package walls. Another method is
to
measure the time taken for a given mass of ice to melt.
Example 1
Various cardboard boxes were constructed with various product bags and in each
bag 4.5Kg of -1 °C ice was placed and the time taken for the ice to
melt to 0°C with
i s an external temperature of 20 °C was measured, and the R value for
the package
was calculated.
Box A was a one piece cardboard box with 3mm flutes having an average surface
area of 1.Om2 and the product bag was a 100micron thick polyethylene bag.[non
inventive comparison box ]
2o Box B was a one piece cardboard box with 3 mm flutes and 2cm thick baffles
on
the internal surfaces of the base) walls and lid. The external surface was
covered
with a laminate of reflective aluminium foil over a 3mm thick plastic bubble
wrap.
The average surface area was 0.89m2 and the product bag was a 70micron thick
- aluminium foil/polyethylene laminate bag.(invention]
2s Box C was a two piece 3mm fluted cardboard box including an enveloping
cover,
having of average surtace area of 1.Om2 . The product bag is of 100micron
polyethylene.[non inventive comparison box]
Box D was a two piece 3mm flute corrugated cardboard box with 2cm thick
expanded polystyrene baffles on inner walls, base and lid. The external
surtace
so coated with a laminate of reflective foil over 3mm thick plastic bubble
wrap. The
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average surface area was 0.89m2. The product bag was composed of 70 micron
thick reflective aluminium foil/polyethylene laminate.(invention]
~ Table 1
BOX Time for ice to R value m2 K/W
melt
A 18.6 hours 0.89
B 40.6 hours 1.73
C 19.5 hours 0.93
D 39.9 hours 1.70
s The two packages according to the invention [B and D] out performed the
prior art
boxes and enable less ice to be needed with the consequence that the package
weight can be reduced.
Example 2
~ o Polystyrene fish boxes of the prior art and the invention were tested with
and
without fish under the same conditions as in example 1. Again 4.5 Kg of -1
°C ice
was placed in the bag and in the second trial 16 Kg of fish chilled to 0 -1
°C was
also included.
Box E was an expanded polystyrene box with 2cm thick base, walls and lid. A
i s 1.5mm fluted corrugated cardboard cover fits over the box. Average surface
area
was 0.9m2. The product bag was 100 micron thick polyethylene.[prior art]
- Box F was the same as box E, with 1.0 cm thick expanded polystyrene baffles
on
the inner walls, base and lid. The external surface of the cover was covered
with
' reflective aluminium foil . Average surface area was 0.85m2. The product bag
was
2o made of a 70 micron thick laminate of reflective aluminium foil and
polyethylene.
[invention]
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Table 2
BOX Time for ice R value m2
to melt KIW
E ice 42.5 hours 1.84
E fish 37.8 hours 1.63
F ice 52.5 hours 2.14
F* fish40.3hours 1.84
s *only 4 Kg of ice was added with the 16Kg of fish
Again this demonstrates the effectiveness of the package construction of the
invention and shows that less ice can be used and still have a better
performance.
Example 3
to Four cardboard boxes were tested with ice only to gauge the effect of
baffles alone,
a reflective product bag alone) as well as a container with neither feature
and one
with both. The conditions were the same as in example 1 with 4.5Kg of -1
°C ice
being used and the ambient temperature being 20°C.
Box K is the same as box C.
is Box L is a two piece 3mm fluted cardboard box including an enveloping
cover.
Baffles 2cm thick are arranged on the inner walls base and lid. The average
surface area is 0.89m2. The product bag was 100 micron thick polyethylene.
Box M is a two piece 3mm cardboard box including an enveloping cover.The
average surface area is l.Om2. The product bag is 70micron thickreflective
ao aluminium foil and polyethylene.
Box N is the same as box D.
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Table 3
BOX Time for ice R value m2
to melt KIW
K Ice 19.5 hours 0.93
L Ice 18.8 hours 0.80
M Ice 21.3 hours 1.02
N Ice 39.9 hours 1.70
These figures show a dramatic improvement when the combination of reflective
s bag and baffled container is used.
Example 4
Four expanded polystyrene boxes were used one with a reflective product bag,
but
without baffles one with baffles, one with the reflective bag and one with the
combination. Both -1 °C ice only and ice plus 1 fi Kg of fish chilled
to 0-1 °C, were
io used in each box. The quantity of ice only was 4.5Kg unless otherwise
specified.
The conditions were as in example 2 except that the ambient temperature was
22°C.
Box W was the same as box E
Box X was the same as box E with 1 cm thick expanded polystyrene baffles on
the
is inner wall, base and lid. The average surface area was 0.85m2. The product
bag
was 100 micron thick polyethylene. Only 4Kg of ice was added with the fish.
Box Y was the same as box E. The average surface area was 0.9m2. The product
bag is 70micron thick reflective aluminium foil and polyethylene.
Box Z is the same as box F. Only 4Kg of ice was added with the fish.
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Table 4
BOX Time for ice to R value m2
melt KIW
W ice 37.5 hours 1.61
W fish+ice34.1 hours 1.47
X ice 37.4 hours 1.52
X fish+ice31.9 hours 1.46
Y ice 42.3 hours 1.79
Y fish+ice36.6 hours 1.58
Z ice 51.7 hours 2.10
Z fish+ice37.4 hours 1.71
The higher ambient temperature has a significant effect on the time taken to
melt
the ice. Even with less ice the combination out performed the other boxes when
fish was present.
s Example 5
A series of experiments was conducted to assess the effect of using low
temperature ice. The following tables show the time for the ice to melt when
various initial ice temperatures and varying container combinations are used.
to Table 5A
Cardboard boxes containing 16.8 Kg. chilled salmon.
_[external temperature 19-20°C]
Box DesignFish Chill treatmentIce Qty(Kg)Ice Temp.( Melt time
C)
Box C 0-1 C in ice 4.5 -1 16.1 hrs
Box C -0.5 C in ice 4.5 -20 23.5 hrs
slurry
Box M -0.5 C in ice 4.5 -20 33.8hrs
slurry
SUBSTITUTE ~~ iEf-_T (RULE 26)
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Table 5B
Expanded polystyrene boxes containing 16.8Kg chilled salmon
[external temperature 19-20 °C]
Box Design Fish Chill treatmentIce Qty(Kg)Ice Temp. Melt time
(C)
Box E 0-1 C in ice 4.5 -1 37.1 hrs
Box E -0.5 C in ice 4.5 -20 57.3 hrs
slurry
Box F -0.5 C in ice 4.0 -20 62.7hrs
slurry
s Table 5C
Expanded polystyrene boxes [ box E ] containing 4.5Kg ice only
[external temperature 22 °C]
Ice Type Ice Temp(C) Melt Time (Hours)
Crushed -1 32.7
Flake -8 37.1
Flake -11 43.9
Table 5D
to Expanded polystyrene boxes [ box E ] containing 16-17Kg chilled salmon
plus 4.5 Kg ice [external temperature 22 °C]
Fish Qty Fish Chill treatmentIce Type Ice Temp.(Melt time
(Kg) C)
16.3 0-1 C in ice Crushed -1 33.8 hrs
17.1 0-1 C in ice Flake -11 38.7 hrs
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The results of set out in tables 5A to 5D show the significant improvement
achieved
when low temperature ice is used.
Example 6
s A series of experiments was conducted to assess the difference in
performance of
metallised films as the external reflective layer of the product bags as
compared
with foil laminate bags. The metallised films tested were either 12micron
metallised
P E T [polyethylene terephthalate] film or 30 micron metallised BOPP [bi-
axially
oriented polypropylene] film. These were compared with the foil laminate bags
of
to the kind described in the above examples.
Table 6
Metallised film bags vs FoilIPolymer laminate bags
Trial Conditions Time for
ice to
melt to
0C
12 micron 30 micron 65micron
metallised metallised laminate
of
PET BOPP foil/PE
Bag containing 2 kg of -1 29.9 hours - 27.4 hours
C ice inside
box E 18.5 C
Bag only containing 2 kg of - 29.3 hours 24.4 hours
-1C ice
18.5 C
Bag containing 4.5kg of -1C - 37.1 hours 30.5 hours
ice
inside box B 18.5 C
Bag containing 4.5 kg -1 C - 57.8 hours 51.4 hours
ice inside
box E 19 C
IBag containing 16.1 Kg chilled- 42.8 hours 38.9 hours
fish
{0-1 C)+ 4.5kg of -1 C ice
inside box
E 20C
Bag containing 16.1 Kg chilled- 44.4 hours 40.3 hours
fish
{0-1 C)+ 4 kg of -1 C ice
inside box
F 20 C
These results demonstrate that the metallised films extend the ice melt time
for a
1 s period longer than the foil/polyethylene laminate. Care needs to be taken
with the
metallised films as they are not as robust as the foil /PE laminate.
SUBSTITUTE SHEET (RULC 26)
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Example 7
A series of experiments was conducted to assess the utility of vacuum
evacuation
and sealing of the product bags.
A 60 micron LDPE [low density polyethylene] film was heat sealed to form
product
s bags. These were filled with chilled fish and ice and placed inside an EPS
box [box
E]. The bags were evacuated to remove air surrounding the fish and ice, then
sealed. The heat transfer properties of of these bags were compared with that
of
100micron LDPE bags that were unsealed and not evacuated inside an EPS box
[box E].
to In a second part of the experiment 30 micron metallised BOPP sheet was heat
sealed to form product bags. These were filled with fish and ice and placed
inside
B flute cardboard boxes [box BJ. One bag was vacuum evacuated and sealed and
then its heat transfer properties compared with those of a similar unsealed
metallised bag in box B.
is Table 7
Evacuated bag comparisons
Box/Product bag Quantity Ice QuantityStandardisedTime for
of ice
combination chilled {_ o J External to melt
fish 1 C to
0-1 Tem erature 0 C
C
Box E + 100micron 16.8kg 4.5 kg 20 C 36.5 hours
PE (ave)
bag
Gave of
4
trials
Qox E + evacuated/sealed16.5kg 4.5 kg 20 C 39.3 hours
(ave)
Omicron PE bag
(ave of
4
trials
Box B + 30 micron 16.9kg 4.5 kg 20 C 26.9 hours
(ave)
metallised BOPP bag
{ave of
2
trials
Box B + evacuated 16.8kg 4.5 kg 20 C 28.1 hours
/sealed (ave)
30 micron metallised
BOPP ba
These results show a 7% improvement by the evacuated LDPE bag.
For the metallised film there was only a slight improvement gained with
evacuation.
The 30micron metallised BOPP films are less reliable in terms of vacuum
sealing
SUBSTITUTE SHEET (RULE 26)
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and leak resistance than the thicker LDPE bags. This may explain the reduced
performance enhancement with evacuation of metallised films compared with
LDPE. The metallised bags could be made more robust in terms of tear
resistance
and vacuum sealing if a layer of LDPE was laminated to the non reflective BOPP
s surtace.
From the foregoing description it can be seen that the combination, of an
inner
container having an external reflective surface and an outer container having
inward protrusions on its base and walls to create an insulating air space,
provides
a cost effective improvement in chilled transportation.
SUBSTITUTE SHEET (RULE 26)
