Note: Descriptions are shown in the official language in which they were submitted.
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Containers for transport of food.
The present invention relates to a new type of EPS containers.
Background
Food, especially fresh fish, is often transported in EPS containers (Expanded
Polystyrene).
Transport in EPS containers is the least expensive and efficient way to
transport fish. Such a container is
light, functional, hygienic, robust and may be adjusted to a European pallet.
The fish is placed into the
container together with ice, possibly an absorbent, and finally a lid of EPS
is laid onto the container, and
fastened with straps. Such containers having a lid and straps are well known
in prior art, for instance
from Bewi AS.
During transportation, most of the ice will melt, and in order to prevent the
food from lying in
water, which, would reduce the quality, most EPS containers are performed with
holes for drainage,
whereby superfluous water may drain out. During long transport(ation)s, water
will thus flow out of the
containers, and from the vehicle, such as a trailer. This water is mixed with
fluids from the fish, and is
thus unfavourable discharge. The alternative is to use sufficient amounts of
absorbents, which i.a. is
done for transportation by plane.
To fill the containers with ice instead of food is very unfavourable, and
renders the
transportation expensive. One may also use dry ice instead of wet ice, but dry
ice is more expensive, and
should not directly touch the food. The alternative for using EPS containers
with ice, is to use other
containers and perform other ways of cooling during the entire transport. The
containers must also be
strong enough to be stackable and to allow being moved and handled without
danger for falling apart.
Many different types of trays or small containers of XPS - extruded
polystyrene are known, for
instance from JP 7060922. XPS are produced in flat plates, and an XPS-tray is
produced by punching a
tray from such an XPS plate. To perform the punching process, the plate must
be relatively thin, and
thus it is not possible to produce a container of XPS having sufficient
strength. The thin walls are not
providing sufficient insulation, and the XPS-trays must thus be cooled from
the outside.
Object
A main object is that the EPS containers according to the present patent
application should be
lighter and have smaller outer volume than known EPS containers having the
same inner volume. A
further object is that the containers should be air- and fluid tight, in order
to render the atmosphere
inside controllable. Yet another object is that the containers should provide
better possibilities for
branding.
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The invention
The objects are achieved with an EPS container according to the characterizing
parts described
hereinbelow. Further advantageous features are stated in the accompanied
dependent claims.
The invention is related to a container having sidewalls and floor of EPS,
wherein the traditional
EPS lid is replaced by a plastic film being fastened directly to the EPS
container. By using this film a
substantial reduction of volume and weight is achieved, and if desirable, it
is possible to obtain a
container being liquid and/or gas tight. Using a transparent plastic film
further makes it easier for the
end user to inspect the contents of the container, as it no longer needs to be
opened to allow inspection
of its contents. The film also offers a good possibility for branding, because
it can be printed directly
onto the plastic film. Directly printing onto EPS is possible, but the result
is often poor, and it causes a
lot of wreckage. The alternative is to use stickers, but that involves extra
costs and work.
In one embodiment the is provided a container for liquid and/or gas tight
transportation and/or
storage of food, wherein the container comprises a lid and has sidewalls and
floor of expanded
polystyrene (EPS), characterized in that the upper edges of the sidewalls of
the container are designed
with a horizontal track, and that said lid comprises a plastic film attached
to the container by gluing in
the horizontal track with an adhesive of a type being able to being heat
activated at a temperature
lower than the deformation temperature and/or melting temperature of EPS.
There is also provided a method for producing an EPS container by
a) moulding a container having sidewalls and floor of EPS in traditional way,
wherein the improvement comprises:
b) applying an adhesive to the upper edges of the sidewalls,
c) activating the adhesive, and
d) applying a plastic film over the container, and guiding it downwards until
it comes in contact
with the adhesive and further down until contact with the upper edge of the
container.
An adhesive is used to fasten the plastic film to the EPS container. Even if
this adhesive is not
supposed to contact the contents of the container directly, it is still an
advantage to use an adhesive
being approved by FDA for indirect contact with food. The adhesive must fasten
well to EPS, and
preferably have a lower melting point than EPS, so that the EPS is not
deformed or melted when the
adhesive is supplied. When EPS melts, styrene gas is produced, and styrene gas
is possibly cancerous for
humans.
= By "gluing" it, is in this application meant use of an adhesive/glue for
fastening two parts to each
other, releasably or durably. By "adhesive" it is meant any kind of fastening
means being suitable for
fastening two parts to each other, releasably or durably. Different types of
adhesives may be used,
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preferably adhesives applied in one step, and reactivated in another, for
instance adhesives being
activated by temperature, pressure, ultrasound or ultraviolet light. It may
also be used adhesives
applied in one step and cured in another. In an alternative embodiment, a kind
of plastic firstly being
applied to the EPS container is used, and when the plastic film is applied,
the film is welded to the plastic
already being applied to the EPS container. It is, of course, a premise that
the plastic being applied to
the EPS container adheres to EPS, and does not loosen during the welding. A
preferred example of an
adhesive being reactivated with heat, is ethylene vinyl acetate (CAS# 24937-78-
8, also known as EVA). It
is a copolymer of ethylene and vinyl acetate. The weight ratio of vinyl
acetate is normally varying
between 10 and 40%. The terms "activating" and "reactivating" can be used
interchangeably.
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In an especially preferred embodiment, the adhesive is applied immediately
after production of
the container, in such a way that the adhesive is applied in a dry,
controllable environment. The
adhesive may also be applied after the contents of the container is put in
place, but then water,
ice or other elements might prevent optimal adhesion between adhesive and EPS.
After the
contents are placed in the container, the adhesive must be reactivated and the
plastic film applied.
If the characteristics of the adhesive so allows, it may also be moulded into
the EPS container
during production.
In an alternative embodiment, the upper edge of the sidewalls of the EPS
container, is provided
with a horizontal, peripheral track where the adhesive is placed, in such a
way that the contact
surface between EPS and adhesive is as large as possible without changing the
thickness of the
wall.
The plastic film being placed as lid on an EPS container, must also be
approved for food,
corresponding to the adhesive. The plastic film is preferably gas tight, and
should have high tensile
strength, for instance about 13 MPa. Furthermore it is a premise that the film
fastens well to the
adhesive, and that its properties does not change during the reactivation or
curing of the adhesive;
for instance it must have a melting temperature higher than the reactivation
temperature of the
adhesive, in cases where the glue should be reactivated by heat. In order to
achieve a film having
satisfying characteristics it may be an advantage to use a plastic film
comprising several layers, a
laminate. Besides, it is preferred to allow printing directly onto the plastic
film, possibly on one of
the layers if a laminate is being used, and that it is produced in a non-
dewing quality.
The invention also comprises a method for producing a container as described
above,
comprising the steps of
- moulding a container (1) having sidewalls and floor of EPS in a regular way,
- applying an adhesive on an upper edge of the sidewalls,
- laying a plastic film (5) over the container, and guiding it down at the
least until contact with
the adhesive is_achieved.
The container is filled with desired contents after moulding or preferably
after the adhesive is
applied.
The method also comprises a further step for reactivating the glue after it is
applied onto the
container, and most preferably it is reactivated after the plastic film is put
onto the box, in such a
way that the adhesive will be reactivated through the plastic film. Finally it
is an advantage that
the plastic film is guided down until contact with the adhesive, and further
until contact with the
upper edge of the container is achieved.
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By using EPS containers according to the present invention, one achieves
reduced weight and
reduced volume. Compared to use of traditional containers this offers large
economic cuts upon
transportation. When one also may achieve a completely gastight container, the
fish may be
packed in a controlled atmosphere, and this offers new methods for packaging
and transporting
fresh fish. For instance a reduction of the amount of ice will contribute
substantially to further
lower the costs for transportation.
,By replacing the lids with a plastic film, the underside of the floor and the
upper part of the
sidewalls and/or upper edge may be performed with reciprocal designs, in such
a way that the
floor of an adjacent container being stacked on top, will function as an
insulating lid. This gives a
further reduction of the outer volume of the container, and allows more
containers to be stacked
in the height, without increasing the outer measures of the pallet. This
reduces the transportation
costs further.
Example
=The invention will in the following be described in the form of an example,
wherein a container
having sidewalls and floor of EPS is provided with a plastic film lid, and
wherein a number of
containers are placed on a pallet. The example is shown in the enclosed
drawings, where
Figure 1 shows a container having sidewalls and floor of EPS, while adhesive
is applied at the
upper edge of the sidewalls,
Figure la shows an enlarged section of Figure 1, where the track having
applied adhesive is
shown in detail,
,Figure 2 shows the container of Figure 1, having a plastic film glued in
place, and
Figure 3 shows a pallet of containers according to present invention, compared
to a pallet of
traditional containers.
Figure 1 shows a fish container 1 having sidewalls and floor of EPS (in this
case an EPS having a
melting temperature of 103 C is used) designed to achieve a plastic film as
lid instead of a
traditional EPS lid. The container is designed with a horizontal track on the
upper edge of the sides
of the container, wherein the track is designed to provide a carrier surface
for the adhesive. In the
shown embodiment in Figure 1, and as shown in detail in Figure la, the
adhesive 2 is applied to
the track. The upper edges of the container is further provided with a
discontinuous, elevated
outer edge 3, which is opposite to recesses/grooves 4 in the underside of the
container, in such a
way that containers can be steadily stacked high.
In a specific preferred embodiment of the invention, a EVA adhesive, for
example Krystal Lim
FDA 105, is applied to the track 2, at a temperature where the adhesive is
liquid or semi-solid, but
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under the melting temperature for EPS. Upon use of Krystal Lim FDA 105 this
will be a
temperature of about 70 C. Once the adhesive is applied, the container 1 is
cooled and
transported to the site of use, where fish and ice are placed into the
container. When the desired
contents are placed in the container, a plastic film 5, for instance a 40 Lim
thick two-layer plastic
film of PE and EVA, wherein the EVA layer turns towards the adhesive, is
placed over the
container, and guided down towards the upper side of the container, until the
plastic touches the
adhesive. Then the adhesive is reactivated, preferably by heat, at a
temperature higher than the
melting temperature for the adhesive, but lower than the melting temperature
for EPS. The
reactivation of the adhesive may for instance be performed by using a frame
being lowered onto
the plastic film and heating the adhesive through it. In cases where the
adhesive is Krystal
adhesive FDA 105, the frame may have a temperature of 80 C. The frame must
have the same
shape as the adhesive 2, but may advantageously be narrower in order to avoid
direct contact
between the hot frame and the EPS container.
,While the adhesive is being reactivated, the film 5 is lowered further, and
preferably until the
film is in contact with the upper edges of the container, in such a way that
it is glued to the EPS
container. A container provided with such a plastic film is shown in Figure 2.
There are several machines in prior art, for fastening plastic films as lids
to trays of other
materials, for instance plastic trays, preferably by lamination of plastic
layers. With small
adjustments these machines may also be used for fastening a plastic film to a
container according
to,the present invention, which will be obvious to a person skilled in the
art.
The savings by using plastic films 5 instead of traditional EPS lids 6, are
large. A traditional lid
weighs 200 gram, and a plastic film with adhesive, according to the example
above, weighs about
g. The weight reduction per container will thus be about 185 g, and per pallet
(24 containers)
24*185 g, i.e. 4,440 g. However, to ensure that a hole is not made in the lid
of the uppermost
containers, and to avoid loss 'of cold, it is preferred that the uppermost
layer has traditional layers
insaddition, and the reduction per pallet will thus be (24-3) * 185 g = 3,840
g. The weight reduction
of the containers themselves, due to new design having elevations and recesses
comes in addition.
A lid adds about 2 cm to the height of a container, and the volume reduction
per pallet (8
containers on top of each other) will thus be 7 * 2 cm; 14 cm. However, when
the containers
further are designed with elevations on the upper edge and opposite recesses
on the underside of
the floor, the containers can be stacked more closely than before, and the
total volume reduction,
having containers according to the present invention, is as shown in Figure 3,
23.9 cm, or about
230 litres.
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Above is shown and described a preferred embodiment of the present invention.
The Figures
and example are only given to illustrate an embodiment and should not under
any circumstances
be interpreted as limiting to the invention which is defined by the enclosed
claims.
