Note: Descriptions are shown in the official language in which they were submitted.
~ 1 3 r~ 2 t~ ~3 s
` W~93/23294 PCT/~U93/00194
MOULDED CONT~INER
Field of the Invention ,-
This invention relates to moulded containers suitabXe for
supporting fox display and containing food and other products.
The invention ~inds application in a wide range of containers,
including moulded trays for food products such as meats, c~kes
and various forms of so-called fast-foods, and lidded containérs
sui~able for ~ood p~oducts such as hamhurgers, pizzas and all
other forms of fas~-foods.
Backoround of the Invention
Food products such as meats, cakes etc. are usually
displayed in supermarkets on shallow trays covered by a plastic
film. The most widely used tray is the moulded polystyrene foam
,.
tray which is durable and may be manufactured at relatively low
cost. Similarly, containers having integrally hinged or separate
lids are also moulded from polystyrene foam and are wîdely used
to package fast-foods su~h as ha~urgers.
~oulded polystyrene foam trays and containers are being
increasingly criticized for their i~pact on pollution of the
environment and ~heir:lack of re~yclability. H4wever, ~ntil the
present invention, few if any practical alternatives of
comparable cost have been developed by the packaging industry.
For example, mouldad trays and integrally hinged lidded
containers, such as hamburger cartons, have been made from so-
called box board, but such t~ays and containers are prohibitively
expensi~e when made from sufficiently rigid box board materials.
When made from lighter box board material , the trays and
containers have insufficient strength to provide an acceptable
alternative to the polystyrene foam products.
Single-face corrugated board is widely used in the packaging
industry as a cushioning material. It is not traditionally used
to form cartons or boxes, although ~roposals have be~n made in
AU-B-30298/63 (277947) to use modifled ~ingle-face orrugated
board for this purpose, and in AU-B-44160/64 (284298~ to use
multi-ply wound single-face board to form tubular containars.
Nei~her of these proposals has found commercial acceptance due
to ~he greater strength and more widely accepted use of standard
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W093t23294 i PCT/AU93/00194
(double-face~ corrugated board in the packaging industry. It has
never been proposed to make moulded containers or trays from
single-face corrugated board, the expectation being that it~would
not be possible to form moulded containers and trays from such
material. It has been surprisingly found by the present
applicant that by moulding 5ingle-face corrugated board in a
particular configuration, containers and trays are able to be
moulded in a manner which retains its shape for the typical life
of such a product and provides a product having acceptable
strength properties.
~ummary of the invention
The invention provides a moulded container or tray suitable
for food products, comprising a blank of single-face corrugated
board having a liner element and a corrugated element moulded to
define a base, an upstanding side wall and a rim, characterized
by smoothly radiussed regions between the base and said side wall
said corrugated element subs~antially retaining its integrity in
said radiussed regions to provide a moulded container or tray of
the required rigidity.
By moulding the container or tray from single-face
corrugated board and m~intaining, by means of the smoothly
radiussed regions, the integrity of the corrugations in the
corruga~ed element of the board except at the corners where
deformation must occur to shape the product, a product having
equivalent or superior rigidity when compared with a moulded
polystyrene foam produc+ is produced with none of the
environmental disadvantages associated with moulded polystyrene
foam products.
The container or tray is preferahly moulded from single-face
.corrugated board which has been coated to increase its water and
hea~ resistance and to further increase its rigidity and to
retain its moulded shape~ although advantage may be gained by
coati~g only t~e corrugated element. Various acrylic or modified
acrylic resins known in the packaging industry may be used for
this purpose and have the advanta~e that they are biodegradable
and approved for use in $he food industry.
In one preferred embodiment described in great~r deta 1
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.; W093/23~94 PCT/AU93/00194
below, the invention finds applicati~ as a food product tray.
Howe~er, the invention is equally ap~,licable to other moulded ¦
containers, such as hamburger and pizza containers h~ving
integrally hinged lids and shaped in the nature of a so-called
clam shell container. :
The invention fur*~er provides a me~hod of forming a moulded
container or tray comprising the steps of forming a shaped blank
from single-face corrugated board having a liner el~ment and a
corrugated element, moulding the blank under h . at and pressure
to form a moulded container or tray havi~g a base, an upstanding
side wall and rim, said moulding being performed to provide
smoothly radiussed regions between the base and the side wall to
maintain the integrity of the corrugated element in these regions
to thereby form a moulded container or tray having the re~uired
rigidity.
In a preferred form of the invention, the single face
corrugated board is preferably made from paper which has been
treated to increase its resistance to moisture and heat and
increases the rigidity of the moulded product. A suitable
coa~ing comprises any one of numerous acrylic or modified acrylic
resins used in the packaging industry~ :
Brief description of the drawinas
In the accompanying drawings:
Figure 1 is a perspective view of a moulded tray embodying
the invention;
Figure 2 is a plan view of the moulded tray, and
Figure 3 is a side eleva~ion showing a half sectivn through
the corrugationsO
I ~escription of preferred e~bodiment
Referring to the drawings, a moulded tray ~hodying the
inve~tion is seen to comprise a base portion l, a side por$ion
2 and a rim portion 3, with the base and side portions l and 2
conn~cted by a smoothly radiussed p~rtion 4 and the side portion
and rim portion 2 and 3 co~nected by a further smoo~hly radiussed
portion 5. The tray is moulded from a shaped blank of single-
~ace corrugated board having a liner medium M and a corrugated
medium C, with the corrugations directed inwardly of the tray.
2 ~ ~ ~ 2 ~
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W093/23294 PC~/AU93/00194 '-.
By moulding the tray with smoothly radiussed portions 4 and 5,
the integrity of the corrugations of the corrugated medium C in
these regions is substantially maintained thereby produc~ng a
moulded product having superior rigidity. ~ .
The blank is creased in the regions which will be occupied
by ~he corners of the moulded tray to re~uce cracking of the
board in these regions and to promote retention of the moulded
shape. The creases are clearly visible in figures 1 and 3 of the
drawings.
To increase the resistance to moisture and heat of the
moulded tray and to further increase the rigidity of the tray,
the single face board is preferab~y coated with an acrylic resin
or a modified ac~ylic.res~n of the type commonly used in the
packaging industry. The coating is most conveniently performed
on the paper medium which subsequently deines the liner and the
corrugated medium in the single face board blank. By modified
acrylic resin is intended acrylic resins to which a cross linking
agen~ known in the art has heen added to increase the hardness
o the resultant coating, or modified base resins, such as
styrenated acrylic resins.
The moulding process is perfo~med under heat and pressure,
and to reduce the Iikelihood of cracks developing in the
corrugated board product, the blank should have a moisture
content substanti~lly falling in the range eight to ten per cent.
Generous clearances are maintained between the male and female
platens of the moulding die to further ensure t~e integrity of
the corrugations in the corrugated ~edium C at all regions of the
product except at the corners referred to above where the blank
is pre-creased to encourage bunching of the material to defi~e
the desired shape of the moulded tray.
Coating of the single-face board with a suitable acrylic
resin or modified acrylic resin is prefer bl~ performed before ' ~~
the liners are cor~ugated and glued together. The use of a
coated product not only improves the retention of the moulded
sha~e and increases the rigidity of the product but also reduces
the likelihood of crackin~ of the board by pro~iding a seal ~o
the exposed paper s~rface and allowing the paper and coating to
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: W093/ 3294 P~T/~U93/~194 -.
soften and flex under the heat and pressure used in the moulding
process~ After moulding, the coating cools and hardens to
maintain the moulded shape and to increase the rigidity of the , -
productO
It will be appreciated from the above that products
manufactured in accordance with the in~ention have the following
advantages:
1. They have equivalent or superior str~ngth when compared
with moulded polystyrene foam products, - :~
2. They have ade~uate resistance to moisture and heat,
3~ They may be made from rerycled materials whicn are
bio~egradable and may in turn be recycled.
4. The positioning of the corrugations inside the
~ontainer reduces food adhesion and increases insulative
properties, and may obviate the need for blood absorbing inserts
such as are used in the packaging of meat. The ability of the
corrugated medium to absorb such liquids may be controlled by
modifying the coating applied to the corrugated medium.
