[0001] The present invention relates to a method of packaging an article, in particular,
to a method of packaging a food product. The invention also relates to a package with
an enclosed article.
[0002] Conventionally articles packaged in shrinkable material can be compressed under vacuum.
Particularly in the case of food products this may be presentationally unappealing
to customers. When food products are packaged under a preserving atmosphere, the products
are often not constrained from moving around within the packaging. This can also result
in an unappealing display of the product.
[0003] Some products, notably toys, are held in place within a box with a stiff sheet of
PVC or polyurethane esther between 0.05 and 0.5mm thick. Such PVC or polyurethane
sheets are not recommended for food applications as not all properties necessary (sealability,
gas barrier, food contact) can be satisfied.
[0004] According to the present invention, there is provided a method of packaging an article
comprising the steps of:
positioning two sheets on opposite sides of said article, at least one of said two
sheets being comprised of a flexible shrinkable material;
sealing between said two sheets around said article by forming at least one seal;
and
attaching said two sheets substantially along said at least one seal to a frame member
such that said frame member surrounds said article.
[0005] The advantage of this method is that the presentation of the articles in the packaging
may be significantly improved over conventional packaging. The thickness of the flexible
shrinkable material can be made thinner than that of the prior art (for example, between
12 and 40 µm thick) thereby reducing cost. The article need not be compressed under
vacuum and may be kept under a preserving atmosphere if so desired.
[0006] The method may further comprise the step of shrinking said shrinkable material thereby
to suspend said article in said frame member under tension forces which are developed
in said shrinkable material because of being constrained by said frame member. Thus,
the article may be held securely in place thereby improving presentation of the product.
Because the article may be constrained within the frame member by tension in the shrinkable
material around the product, it is possible to present the article in a more appealing
manner than previously. For flat products, the shrinkable film is capable of forming
a high suspension/retention tension.
[0007] According to the present invention, there is further provided a packaging and an
article said packaging comprising:
two sheets, at least one of which is comprised of a shrinkable material, positioned
on opposite sides of said article; and a frame member provided surrounding said article;
wherein said two sheets are sealed around said article with at least one seal and
are attached to said frame member substantially along said at least one seal.
[0008] Preferably the article is a food product.
[0009] The present invention will now be described by way of example only with reference
to the following drawings in which:
Figure 1 is a schematic cross-sectional view through a packaging according to a first
embodiment;
Figure 2 is a schematic cross-sectional view through a packaging according to a second
embodiment;
Figure 3 is a schematic cross-sectional view through a packaging according to a third
embodiment;
Figure 4 is a schematic cross-sectional view through a packaging according to a fourth
embodiment; and
Figure 5 is a schematic cross-sectional view through a stack of packagings according
to a fifth embodiment.
[0010] Like reference numerals are used to indicate like objects.
[0011] A first embodiment is illustrated in Figure 1. An article 30 is positioned between
a first sheet 10 and a second sheet 20 both sheets being comprised of a shrinkable
material. A seal 150 is formed between the two sheets 10, 20 around the article 30.
Thus, the article 30 is contained between the two sheets 10, 20 and is protected (i.e.
sealed) from the atmosphere. The two sheets 10, 20 are attached to a frame 100. The
frame 100, in the embodiment of Figure 1, is a ring and is attached to the two sheets
10, 20 substantially along the seal 150 through a second seal or joint 180.
[0012] Tension is created in the two sheets 10, 20 by shrinking those sheets 10, 20. Because
that shrinking is constrained by the frame 100, the sheets 10, 20 are left in tension
suspending the article 30 in the frame member 100.
[0013] A method of forming the packaging illustrated in Figure 1 will now be described.
First, two sheets 10, 20 of a flexible shrinkable material are placed on opposite
sides of the article 30. Examples of flexible shrinkable material are oriented "heat-shrinkable"
films which shrink when heated to a critical shrink temperature close to the temperature
at which they have been oriented and which then shrink by a certain amount generating
shrink tension. Other examples are so-called "shrink" films which shrink upon heating
to a critical temperature close to the melting point and which only develop a high
shrink tension upon cooling. The "heat shrinkable" films can be obtained by the so-called
trapped bubble technology or by other technology such as flat extrusion or co-extrusion
of a cast sheet, followed by quenching, re-heating to the suitably selected orientation
temperature and orientation. "Shrink" films are typically obtained by the so-called
"hot-blown" method. Both "heat-shrinkable" and "shrink" films are known in the art
as well their methods of manufacture.
[0014] Specific examples of heat-shrinkable film are those such as disclosed in EP-A-0,236,099
or WO 97/30844. Those patent applications describe the films with barrier layers comprising
ethylene-vinyl alcohol copolymer optionally blended with polyamides. Other films,
containing gas barrier materials other than ethylene-vinyl alcohol copolymers, such
as PVDC or polyamides, are also suitable.
[0015] Whilst mono-layer barrier films may be used, in the preferred embodiment illustrated
in Figure 1, the two sheets 10, 20 also comprise a heat-sealing layer suitable to
seal to itself and also to the material used for the frame member 100. A suitable
heat sealing layer comprises polyolefins, modified polyolefins, styrene polymers and
copolymers. The term "polyolefin" refers to a thermosplastic resin obtained by polymerization
of an olefin or by copolymerization of two or more olefins or of one or more olefins
with other comonomers, wherein the olefin units are anyway present in larger amounts
than any possibly present comonomer. Suitable examples of "polyolefins" are polyethylene,
polypropylene, polybutene, ethylene-α-olefin copolymers either heterogeneous or homogeneous,
ethylene-vinly acetate copolymers, ethylene-acrylic acid or methacrylic acid copolymers,
ethylenepropylene copolymers, ethylene-propylene-butene terpolymers, etc. The term
"modified polyolefin" means a polyolefin characterised by the presence of functional
groups such as typically anhydride or carboxy group. Examples of said modified polyolefins
are graft copolymers of maleic acid or anhydride onto ethylene-α-olefin or ethylene-vinyl
acetate copolymers, polymerisation products of these with other polar monomers, blends
thereof etc. These polymers may be mixed as known in the art with additives suitable
to improve the manufacturing process, such as slip and anti-block agents or to improve
the film performance such as UV absorbers, anti-fog agents, anti-microbials, oxygen
scavengers, etc. Such multi-layer films have the necessary properties required such
as gas (oxygen) barrier properties, punture resistance, modulus, possibly meat adhesion
and/or anti-fog properties, etc. for packaging food.
[0016] All seals may be made by glueing although - if possible- they are preferably made
by heat-sealing.
[0017] The two sheets 10, 20, if they are comprised of a flexible shrinkable material, need
only be 10 to 40 µm in thickness. Such sheets can easily be formulated to reach food
contact objectives and the required stable properties and dimensions across a large
temperature range. Furthermore, such sheets 10, 20 can provide enough tension when
they have been shrunk in order to hold flat products (such as sliced salami).
[0018] The frame member 100, as mentioned above, is in the shape of a ring. This is not
necessarily the case; the frame member 100 may be any shape so long as it defines
a central through-hole large enough for the article 30 to pass through. The frame
member 100 must be dimensioned and manufactured from a material to withstand the shrink
tension generated by the shrinking of the two sheets 10, 20 (i.e. it should not bend
or buckle) and should be suitable for sealing to the two sheets 10, 20. Suitable materials
include rigid polymers (polypropylene, high density polyethylene, terephthalate, polystyrene
and high impact polystyrene) or foamed polymeric materials (such as polystyrene, polyethylene
terephthalate and polypropylene), corrugated cardboard or polymer corrugated-like
structure obtained by using profile extrusion. The frame member 100 may be produced
by injection moulding; sheet extrusion and punch-in press; sheet extrusion and thermo
forming to increase mechanical properties and punch-in press; and punch-in press of
corrugated cardboard. If cardboard is used, it must be coated with a polymer to ensure
sealability to the sheet 20 or sheet 20 must be formulated to seal directly to cardboard
(e.g. ethylene-vinyl acetate copolymer, very low density polyethylene, and the like
resins). Alternatively it can be attached to film 20 by means of a glue/adhesive.
[0019] In the preferred embodiment, the formation of seal 150 between the two sheets 10,
20 and the formation of the seal 180 between the sheet 20 and the frame member 100,
as well as shrinking of the two sheets 10, 20, are performed at the same time. This
is arranged for by positioning the article 30 in the middle of the frame member 100
and aligning the two sheets 10, 20 and the frame member 100 as required. In order
to form the seals 150, 180 heat and pressure are applied adjacent to the frame member
100 between the frame member 100 and the first (outer) sheet 10. The combined heat
and pressure serve to form the seal 150 between the two sheets 10, 20 and the seal
180 between the second (inner as illustrated) sheet 20 and the frame member 100.
[0020] The two sheets 10, 20 are shrunk around the article 30, mainly during the sealing
to the frame member 100. If additional heat is required this may be provided by air
or water at an elevated temperature in order to increase the amount of shrink tension
in the two sheets 10, 20.
[0021] The amount of shrink required in the two sheets 10, 20 is so that enough tension
is created where the article 30 and the two sheets 10, 20 contact, that motion of
the article 30 during the packaging, transport and handling of the packaging and article
is avoided.
[0022] It will be understood that the product may be packaged either under vacuum or with
a modified atmosphere as is conventional in the art. It will also be understood that
the sealing of the two sheets 10, 20 to one another, the sealing of the sheet 20 to
the frame member 100 and the shrinking of the two sheets 10, 20 may all be performed
at once as described above or may be carried out as individual steps or any combination
thereof.
[0023] In a variation of the embodiment illustrated in Figure 1, one of the two sheets 10,
20 may be comprised of a non-shrink material if desired. For example, sheet 10 may
be comprised of a semi-rigid moulded flexible non-shrinkable material.
[0024] Figure 2 shows a second embodiment in which the two sheets 10, 20 are sealed on opposite
sides of the frame member 200. In such a case there is no seal between the two sheets
10, 20 but a first seal 250 between the first 10 of the two sheets and the frame member
200 and a second seal 255 between the second 20 of the two sheets and the frame member
200. Also in this case the two seals can be made separately or in one single step.
In such a case, if the article 30 is a food product, it may be necessary that the
frame member 200 has the same physical properties with regard to permeability to oxygen,
puncture resistance, sealability, meat adhesion etc. as the two sheets 10, 20. In
a preferred embodiment however, the frame member is perforated in the surface thereof
facing the packaged product in such a way that it may absorb the liquids possibly
released by the food product. In a more preferred embodiment it may also comprise
an outer gas-barrier shell perforated in the surface facing the product and an inner
zone containing an absorbing material in order to absorb and retain the possible drip.
[0025] A further alternative arrangement is illustrated in Figure 3. In this third embodiment,
the frame member 300 comprises two elements 310, 320. In the embodiment illustrated,
the first element 310 and second element 320 are the same though this is not necessarily
the case. The preferred method of forming the packaging is to seal the two sheets
10, 20 and to attach the first 310 and second 320 elements of the frame member 300
in one operation. This is done by positioning the two sheets 10, 20 on opposite sides
of the article 30 and positioning the first and second elements 310, 320 of the frame
member 300 around the article 30 and opposite one another on either side of the two
sheets 10, 20. In this way the first element 310 only contacts the outer side of the
first sheet 10 and the second element 320 only contacts the outer side of the second
sheet 20. In this embodiment, the seal 350 between the two sheets 10, 20 may be made
as an easy peel interface such that the packaging may be easily opened. The easy peel
interface is manufactured in a manner conventional in the art by suitably selecting
the resins used in the sheets 10 and 20. While in an easy-to-open package the seal
between these two sheets should be readily opened by hand the seals between the sheets
and the frame members should be unaffected. There are several mechanisms by which
the easy openability can be achieved in the package of the invention. In a first one,
this is obtained by suitably selecting the innermost sealing layers of sheets 10 and
20 so that upon application of a limited force they separate at their interface ("peel"
one from the other). This can be obtained by suitably selecting resins or resin blends
for said sealing layers of a sufficiently different chemical nature. In a second mechanism
this is achieved by using in at least one of the sheets a thin innermost sealing layer
and an adjacent layer of a thermoplastic material suitably selected in such a way
that the bond between the sealing layer and said adjacent layer is very low. A typical
example is a system where either sheet 10 or 20 or both comprises a very thin layer
of polyethylene- as the innermost sealant - adjacent to a polyamide surface. The force
exerted to open the package breaks through the thin polyethylene sealing layer and
the low bond between polyethylene and polyamide then permits delamination between
these two layers to take place leading to opening up of the package. In a third mechanism,
the desired easy openability is obtained by using in the innermost seal layer, or
in the layer adjacent to a very thin seal layer, of at least one of the sheets 10
and 20, a resin blend that has a low cohesive strength. In such a case the force exerted
to open the package will break said layer along a plane parallel to the layer itself,
with or without prior breakage of the thin sealing layer, to give the easy opening
up of the package.
[0026] A fourth embodiment of packaging is illustrated in Figure 4. In this embodiment the
frame member 400 comprises a first element 410 and a second element 420. The first
element 410 is formed with a recess 415 in an internal surface. The second element
420 has a jamming portion 425 which fits in the recess 415. The two sheets 10, 20
are positioned around the article 30 and a seal 450 (which may be an easy-peel seal)
is formed between the two sheets 10, 20 and the second sheet 20 is attached to the
jamming portion 425 in the same step. Next the jamming portion 425 is jammed in the
recess 415 and the first element 410 is sealed to the first sheet 10. Alternatively,
the article 30 is placed between the two sheets 10, 20 and the edges of the two sheets
10, 20 are positioned in the recess 415 and the jamming portion is used to jam the
peripheral edges of the two sheets 10, 20 into the recess 415. Then the two sheets
10, 20 are sealed to one another and the second sheet 20 is sealed to the jamming
portion 425 and the first sheet 10 is sealed to the recess 415 in the same step. In
both methods of the fourth embodiment, the packaging is subjected to elevated temperature
after the two elements 410, 420 and the two sheets 10, 20 are all sealed together
such that the flexible shrinkable material, of which one or both of the two sheets
10, 20 are comprised, shrinks. Because the periphery of the sheets 10, 20 is jammed
in the recess 415 a shrink tension develops in the sheets 10, 20 comprised of the
flexible shrinkable material, thereby suspending the article 30 in the frame member
400. The frame member 400 is reusable once the packaging has been opened to re-seal
the article in the packaging by the consumer.
[0027] Figure 5 shows a fifth embodiment which is a variation of the third embodiment. In
the fifth embodiment the frame member 500 is also comprised of a first element 510
and a second element 520. However, the first element 510 and the second element 520
are not identical. The first element 510 has, in a first surface substantially parallel
to the sheets 10, 20, a protrusion 515. This protrusion is dimensioned to fit in a
recess 525 formed in a surface of the second element 520 substantially parallel to
the two sheets 10, 20 and opposite the first surface. In this way a plurality of packaged
articles may be stacked as is illustrated.
[0028] Because of the flexible nature of the packaging, a plurality of packages may be wound
on a reel or folded in strips if so desired. Of course all of the embodiments illustrated
may comprise features of the other embodiments. For example, all of the embodiments
may have one of the two sheets 10, 20 formed of a semi-rigid material and may have
the various steps of forming a seal, attaching the sheets to the frame member and
shrinking performed at the same time or in separate operations. The article 30 may,
in all cases, be packaged in a modified (preserving) atmosphere usually an inert gas
of, for example, carbon dioxide. This may be accomplished by gas flushing (with, for
example, nitrogen) between the sheets to expel any oxygen before injecting the modified
atmosphere. Gas flushing may also be carried out with the modified atmosphere or at
least a partial vacuum may be formed between the sheets prior to injecting the modified
atmosphere instead of gas flushing.
1. A method of packaging an article (30) comprising the steps of:
positioning two sheets (10, 20) on opposite sides of said article (30), at least one
of said two sheets (10, 20) being comprised of a flexible shrinkable material;
sealing between said two sheets around said article (30) by forming at least one seal
(150; 250, 255; 350; 450); and
attaching said two sheets (10, 20) substantially along said at least one seal (150;
250, 255; 350; 450) to a frame member (100; 200; 300; 400; 500) such that said frame
member (100; 200; 300; 400; 500) surrounds said article (30).
2. A method according to claim 1, further comprising the step of shrinking said shrinkable
material thereby to suspend said article in said frame member (100; 200; 300; 400;
500) under tension forces which are developed in said shrinkable material because
of being constrained by said frame member (100; 200; 300; 400; 500).
3. A method of claim 2, wherein said step of shrinking occurs simultaneously with said
step of sealing.
4. A method according to claim 2 or 3, wherein said step of shrinking includes subjecting
said shrinkable material to an elevated temperature.
5. A method according to claim 4, wherein said step of shrinking also includes cooling
said shrinkable material from said elevated temperature.
6. A method according to any one of the preceding claims, wherein both of said two sheets
are comprised of a shrinkable material.
7. A method according to any one of the preceding claims, wherein said step of sealing
and said step of attaching are performed simultaneously.
8. A method according to any one of the preceding claims, wherein said step of attaching
comprises attaching said frame member (100) on one side of one of said two sheets
(10, 20) only.
9. A method according to any one of claims 1 to 7, wherein said steps of attaching and
sealing comprise inserting said frame member (200) between said two sheets (10, 20)
and attaching said two sheets (10, 20) on opposite sides of said frame member (200).
10. A method according to any one of claims 1 to 7, wherein said frame member (300) comprises
two elements (310, 320) and said step of attaching comprises attaching each of said
two elements (310, 320) facing one another on one side of different ones of said two
sheets (10, 20).
11. A method according to any one of claims 1 to 8, wherein said frame member (400) comprises
two elements (410, 420), and said step of attaching comprises inserting peripheral
edges of said sheets (10, 20) into a recess (415) in a first (410) of said two elements
and inserting at least a part (425) of a second (420) of said two elements into said
recess (415) thereby to jam said peripheral edges into said recess (415).
12. A method according to any one the preceding claims, wherein said frame member (500)
has a first surface, substantially in the same plane as said two sheets (10, 20),
having a recess (525) and said frame member (500) has a second surface, substantially
in the same plane as said sheets (10, 20) and opposite said first surface, having
a protrusion (515) wherein two of said frame members (500) may be positioned one on
top of another with said respective protrusion (515) engaging said recess (525).
13. A method according to any one of the preceding claims, wherein said shrinkable material
comprises a heat sealing layer suitable for sealing to itself and said frame member
(100, 200, 300, 400, 500).
14. A method according to any one of the preceding claims, wherein said step of sealing
comprises forming at least partly around said article (30) an easy peal seal (350,
450).
15. A method according to any one of the preceding claims, further comprising the step
of injecting a modified atmosphere between said sheets (10, 20).
16. A method according to claim 15, further comprising the step of forming at least a
partial vacuum between said two sheets (10, 20) prior to injecting the modified atmosphere.
17. A method according to claim 15, further comprising the step of gas flushing between
said sheets (10, 20) prior to injecting the modified atmosphere.
18. A method according to any one of the preceding claims, wherein said frame member (100;
200; 300; 400; 500) has a rigidity sufficient to withstand distortion forces generated
during shrinking of said shrinkable material.
19. A packaging and an article (30), said packaging comprising:
two sheets (10, 20), at least one of which is comprised of a shrinkable material,
positioned on opposite sides of said article (30); and a frame member (100; 200; 300;
400; 500) provided surrounding said article (30); wherein said two sheets are sealed
around said article with at least one seal (150; 250, 255; 350; 450) and are attached
to said frame member (100; 200; 300; 400; 500) substantially along said at least one
seal (150; 250, 255; 350; 450).
20. A packaging and an article according to claim 19, wherein said heat shrinkable material
has been shrunk thereby suspending said article (30) in said frame member (100; 200;
300; 400; 500) under tension forces developed in said shrinkable material because
of being constrained by said frame member (100; 200; 300; 400; 500).
21. An apparatus according to claim 19 or 20, wherein said frame member (100) is attached
to one side of one of said two sheets (10, 20).
22. An apparatus according to claim 19 or 20, wherein said frame member (200) is attached
between said two sheets (10, 20), said two sheets being sealed on opposite sides of
said frame member (200).
23. An apparatus according to claim 19 or 20, wherein said frame member (300) comprises
two elements (310, 320) opposite one another on one side of a different one of said
two sheets (10, 20).
24. An apparatus according to claim 19 or 20, wherein said frame member (400) comprises
two elements (410, 420), and peripheral edges of said sheets (10,20) are inserted
in a recess (415) in a first (410) of said two elements, and at least a part (425)
of said second (420) of said two elements is inserted in said recess (415) thereby
jamming said peripheral edges in said recess (415).
25. An apparatus according to any one of claims 19 to 24, wherein said frame member (500)
has a first surface substantially in the same plane as said sheets (10,20), having
a recess (525) and said frame member (500) has a second surface, substantially in
the same plane as said sheets (10,20) and opposite said first side, having a protrusion
(515), wherein two of said frame members (500) may be positioned one on top of another
with said respective protrusion (515) engaging said recess (525).
26. A method according to any one of claims 1 to 18 or a packaging and an article (30)
according to any one of claims 19 to 25, wherein said article (30) is a food product.