U.S. patent application number 14/171105 was filed with the patent office on 2014-08-07 for multi-compartment tray-less package with a rigid frame.
The applicant listed for this patent is Cryovac, Inc.. Invention is credited to Christoforos Chrysanthidis.
Application Number | 20140216975 14/171105 |
Document ID | / |
Family ID | 47720333 |
Filed Date | 2014-08-07 |
United States Patent
Application |
20140216975 |
Kind Code |
A1 |
Chrysanthidis;
Christoforos |
August 7, 2014 |
Multi-Compartment Tray-Less Package With a Rigid Frame
Abstract
A tray-less multi-compartment plastic flexible package has two
outermost films comprising crystallizable polymer, at least two
products, and at least one internal film comprising crystallizable
polymer. The internal film is interposed between the two products
and the outermost films. A peripheral circumferential continuous
seal seals the two outermost films and the internal film together
in a sealing area and delimits two sealed compartments each
enclosing one of the at least two products. The crystallizable
polymer is at least partially crystallized in the sealing area.
Inventors: |
Chrysanthidis; Christoforos;
(London, GB) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Cryovac, Inc. |
Duncan |
SC |
US |
|
|
Family ID: |
47720333 |
Appl. No.: |
14/171105 |
Filed: |
February 3, 2014 |
Current U.S.
Class: |
206/524.6 ;
53/480 |
Current CPC
Class: |
B65B 11/50 20130101;
B65D 75/30 20130101; B65D 65/466 20130101; B65D 81/2023 20130101;
B65D 81/2084 20130101; B65B 2230/02 20130101; B65B 25/068 20130101;
B65D 79/00 20130101; B65D 81/3272 20130101 |
Class at
Publication: |
206/524.6 ;
53/480 |
International
Class: |
B65D 79/00 20060101
B65D079/00 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 6, 2013 |
EP |
13154221.9 |
Claims
1. A tray-less package comprising: i) two outermost films
comprising crystallizable polymer; ii) at least two products; iii)
at least one internal film comprising crystallizable polymer and
interposed between the at least two products and between the two
outermost films; and iv) a peripheral circumferential continuous
rigid frame comprising a peripheral circumferential continuous seal
which seals the two outermost films and the at least one internal
film together in a sealing area and delimits at least two sealed
compartments each enclosing at least a product of the at least two
products, wherein the crystallizable polymer is at least partially
crystallized in the sealing area.
2. The package according to claim 1 wherein only one internal film
of the at least one internal film is interposed between two
adjacent products of the at least two products.
3. The package according to claim 1 wherein: the at least one
internal film comprises at least two internal films; and two
internal films of the at least two internal films are interposed
between two adjacent products of the at least two products.
4. The package according to claim 1 wherein the at least two sealed
compartments comprise from 2 to 20 sealed compartments.
5. The package according to claim 1 wherein the crystallizable
polymer is selected from the group consisting of polypropylene
homopolymers, polypropylene copolymers, high density polyethylenes,
medium density polyethylenes, polyesters, polyamides, polystyrenes,
and blends thereof.
6. The package according to claim 1 wherein the two outermost films
and the at least one internal film each comprise at least 30%
crystallizable polymer by weight of the film.
7. The package according to claim 1 wherein the crystallizable
polymer comprises one or more polyesters that crystallize under
sealing temperatures from 140.degree. C. to 220.degree. C.
8. The package according to claim 1 wherein the crystallizable
polymer comprises one or more polyesters having a melting point
greater than 220.degree. C.
9. The package according to claim 1 wherein the crystallizable
polymer in the sealing area has a percentage of crystallinity
greater than 15%.
10. The package according to claim 1 wherein the two outermost
films and the at least one internal film each comprise a blend
comprising crystallizable polyester and at most 70% amorphous
polyester by weight of the blend, wherein the amorphous polyester
has a glass transition temperature lower than 115.degree. C.
11. The package according to claim 1 wherein the two outermost
films and the at least one internal film are sealable and peelable
crystallizable plastic films.
12. The package according to claim 1 wherein the difference in the
percentage of crystallinity of the crystallizable polymer within
the sealing area with respect to the crystallizable polymer outside
of the sealing area of the package is at least 5%.
13. The package according to claim 1 wherein the percentage ratio
between (i) the combined weight of the two outermost films and the
at least one internal film with respect to (ii) the total weight of
the package is lower than 15%.
14. A method of manufacturing the tray-less package of claim 2
comprising the steps of: stacking in sequence a first of the two
outermost films, a first of the at least two products, a first of
the at least one internal film, a second of the at least two
products, and a second of the two outermost films; simultaneously
sealing the two outermost films and the at least one internal film
together in the sealing area (i) to at least partially crystallize
the crystallizable polymer in the sealing area to form the
peripheral circumferential continuous rigid frame and (ii) to
delimit a first sealed compartment and a second sealed compartment
of the at least two sealed compartments, wherein the first sealed
compartment encloses the first product and the second sealed
compartment encloses the second product.
15. The method of claim 14 wherein: the stacking step comprises
stacking a given number of additional internal films and the same
given number of additional product in a film-product alternating
arrangement between the second of the at least two products and the
second of the two outermost films; and the simultaneous sealing
step forms the same given number of additional sealed
compartments.
16. A method of manufacturing the tray-less package of claim 3
comprising the steps of: stacking in sequence a first of the two
outermost films, a first of the at least two products, a first of
the at least two internal films, a second of the at least two
internal films, a second of the at least two products, and a second
of the two outermost films; simultaneously sealing the two
outermost films and the at least two internal films together in the
sealing area (i) to at least partially crystallize the
crystallizable polymer in the sealing area to form the peripheral
circumferential continuous rigid frame and (ii) to delimit a first
sealed compartment and a second sealed compartment of the at least
two sealed compartments, wherein the first sealed compartment
encloses the first product and the second sealed compartment
encloses the second product.
17. The method of claim 16 wherein: the stacking step comprises
stacking a given even number of additional internal films and half
of the given even number of additional product in a
film-film-product alternating arrangement between the second of the
at least two products and the second of the two outermost films;
and the simultaneous sealing step forms a number of additional
sealed compartments that is equal to half of the given even number
of additional internal films.
18. A method of manufacturing the tray-less package of claim 2
comprising the steps of: stacking in sequence a first of the two
outermost films, a first of the at least two products, and a first
of the at least one internal film; sealing the first of the two
outermost films and the first of the at least one internal film
together in the sealing area to at least partially crystallize the
crystallizable polymer in the sealing area and delimit a first
sealed compartment enclosing the first of the at least two
products; sealing the second of the outermost films to the first
sealed compartment (i) to at least partially crystallize the
crystallizable polymer in the sealing area of the outermost film,
(ii) to delimit a second sealed compartment enclosing the second
product of the at least two products, and (iii) to complete the
peripheral circumferential continuous rigid frame.
19. The method of claim 18 wherein: the at least two products
comprises the first product, the second product, and one or more
additional products; the at least one internal film comprises the
first internal film and one or more additional internal films; and
further comprising sequentially sealing each of the one or more
internal films to the first sealed compartment to at least
partially crystallize the crystallizable polymer in the sealing
area of the one or more internal films and to delimit one or more
additional sealed compartments each enclosing one of the one or
more additional products.
20. A method of manufacturing the tray-less package of claim 3
comprising the steps of: sealing the first of the two outermost
films and the first of the at least two internal films together in
the sealing area to at least partially crystallize the
crystallizable polymer in the sealing area of the first films and
delimit a first sealed compartment enclosing the first of the at
least two products; sealing the second of the at least two internal
films to the second of the two outermost films (i) to at least
partially crystallize the crystallizable polymer in the sealing
area of the second films, (ii) to delimit a second sealed
compartment enclosing the second of the at least two products, and
(iii) simultaneously to attach the second sealed compartment to the
first sealed compartment to complete the peripheral circumferential
continuous rigid frame.
21. The method of claim 20 wherein: the at least two products
comprises the first product, the second product, and one or more
additional products; the at least two internal films comprises the
first internal film, the second internal film, and two or more
additional internal films; and further comprising sealing together
each two of the two or more additional internal films (i) to at
least partially crystallize the crystallizable polymer in the
sealing area of each of the two or more additional internal films,
(ii) to delimit one or more additional sealed compartments each
enclosing one of the one or more additional products, and (iii) to
attach each of the one or more sealed compartments to the first
sealed compartment simultaneously with the sealing together of each
two of the two or more additional internal films.
22. A method of manufacturing the tray-less package of claim 2
wherein: the at least two products comprises a first product, a
second product, and a third product; the at least one internal film
comprises a first internal film and a second internal film; and
comprising the steps of: sealing the first of the two outermost
films and the first internal film together in the sealing area to
at least partially crystallize the crystallizable polymer in the
sealing area of the first films and delimit a first sealed
compartment enclosing the first product; sealing the second
internal film and the second of the two outermost films to at least
partially crystallize the crystallizable polymer in the sealing
area of the second films and delimit a second sealed compartment
enclosing the second product; interposing the third product between
the first and second compartments; and attaching the second sealed
compartment to the first sealed compartment to complete the
peripheral circumferential continuous rigid frame.
23. The method of claim 22 wherein: the at least two products
further comprises one or more additional products; and the at least
one internal film further comprises two or more additional internal
films; further comprising sealing together each two of the two or
more additional internal films to at least partially crystallize
the crystallizable polymer in the sealing area of each of the two
or more additional internal films and delimit one or more
additional sealed compartments each enclosing one of the one or
more additional products; interposing one of the one of the one or
more additional products between each one of the one or more
additional sealed compartments and the adjacent sealed compartment;
and sealing or gluing each of the one or more additional sealed
compartments to the first compartment or to another of the one or
more sealed compartments.
24. A method of manufacturing the tray-less package of claim 3
comprising the steps of: sealing the first of the two outermost
films and the first of the at least two internal films together in
the sealing area to at least partially crystallize the
crystallizable polymer in the sealing area of the first films and
delimit a first sealed compartment enclosing the first of the at
least two products; sealing the second of the at least two internal
films and the second of the two outermost films to at least
partially crystallize the crystallizable polymer in the sealing
area of the second films and delimit a second sealed compartment
enclosing the second of the at least two products; and sealing or
gluing the first sealed compartment and the second sealed
compartment to complete the peripheral circumferential continuous
rigid frame.
25. The method of claim 24 wherein: the at least two products
comprises the first product, the second product, and one or more
additional products; the at least two internal films comprises the
first internal film, the second internal film, and two or more
additional internal films; and further comprising sealing together
each two of the two or more additional internal films to at least
partially crystallize the crystallizable polymer in the sealing
area of each of the two or more additional internal films and
delimit one or more additional sealed compartments each enclosing
one of the one or more additional products; and sealing or gluing
each of the one or more additional sealed compartments to the first
compartment or to another of the one or more sealed compartments.
Description
[0001] The presently disclosed subject matter relates to packaging,
for example, a multi-compartment tray-less package wherein at least
two products in stack are contained into individual compartments
delimited by films, in particular to a multi-compartment tray-less
package characterized by a peripheral rigid frame obtained by
partial heat-induced crystallization of the films along the sealing
area during the sealing operation.
BACKGROUND
[0002] In the field of packaging, there are several applications in
which traditional mono-compartment packages, namely packages in
which the whole product is enclosed in a single compartment, are
not satisfactory while a multi-compartment arrangement--in which
each single item or portion of a product is packaged
individually--would be particularly advantageous.
[0003] For instance, in the field of food packaging, in particular
of packaging of sliced products (cheese, processed meat, salmon,
etc.) the existing mono-compartment packages show some drawbacks:
in particular after opening, leftovers are subjected to rapid
drying and unpleasant organoleptic changes and, unless consumed
quite soon or frozen, they are generally wasted.
[0004] Furthermore, the shelf life of food products traditionally
packaged under modified atmosphere or under vacuum, is drastically
shortened when the mono-compartment package is opened.
[0005] Finally, different food products not always can be combined
in the same mono-compartment package because of odor migration
(e.g. salami and dry ham) or taste cross contamination (e. g.
cheese and processed meat). Another disadvantage of
mono-compartment packages--particularly if comprising important
amount of sliced food products--is that the slices stick to each
other and are difficult to be separated, so very often are damaged
when removed from the package.
[0006] In the medical field, sterilized items such as cannulae,
plasters, needles, bandages etc, when packaged in mono-compartment
packages, must all be used immediately after removal otherwise
contamination by environment bacteria or drying of dipped medicated
items may occur.
[0007] In order to overcome the above problems, multi-compartment
packaging systems, which provide for individually packaged items or
for packaging of single quantity of products, have been
provided.
[0008] U.S. Pat. No. 4,069,348 (L.D. Schreiber Cheese Company)
discloses a sealed package wherein a plurality of portions of
products in a stack are hermetically sealed into individual
compartments by internal films which are releasably sealed to a
backing board. When an individual portion of product is removed,
all others remain hermetically sealed.
[0009] WO 8702965 (Garwood LTD) discloses a method to manufacture a
package for skin wrapped food comprising a base--i.e. a rigid
tray--and a lid with a gas between the base and the lid in order to
preserve the food properties. The package also comprises a flexible
and gas permeable web of skin wrapping plastics material over the
base and the food. A multi-compartment version of this package
comprising a rigid container is disclosed. Useful plastics
materials are polyvinyl chloride (PVC) and polyethylene (PE).
[0010] WO8800907 (Garwood LTD) discloses an improvement of the
method of WO8702965. The package comprises a rigid tray made of PVC
and polyethylene terephthalate (PET) which contains skin wrapped
food. Said food is plastered with a flexible and gas permeable web
made of plastic material which is sealed onto the rim of the tray.
The package also comprises a gas-impermeable lid made of
PET/PVC/PET which can have a compartment to store sauce or
cutlery.
[0011] DE 4440727 (Beiersdorf AG) discloses a package containing at
least 2 plasters which are separated by a layer of material and
which are enclosed between upper and lower cover layers, wherein
the layers may be made of several different polymers. The layers
are bonded together by sealing, cold sealing, gluing or their
combinations.
[0012] These existing multi-compartment packages show many
drawbacks. Multi-compartment packages known in the art need a
supporting tray or a thick backboard to confer rigidity to the
system. Trays significantly increase the volume of the packages and
the ratio between the weight of the plastic materials and the
weight of the packaged item, resulting in less sustainable
packages.
[0013] In addition the presence of trays enhances manufacture and
disposal costs: in fact it brings additional manufacturing steps
related to the production and shaping of the supporting tray,
causing further waste of energy and time and, at the end,
increasing costs.
[0014] Finally, the tray and the lids or wrapping films of
multi-compartment packages of the prior art are made of different
materials, thus making recycling and/or disposal of the entire
package more troublesome.
[0015] There is still the need for a light and sustainable
multi-compartment package which allows: [0016] to preserve single
portions of different or same product(s), also of air sensitive
products, and to use them individually, [0017] to easy open the
compartment which contains each single portion, [0018] to avoid
cross contaminations (odors, taste, bacteria) [0019] to prevent
sticking and breaking of sliced products said package being
sufficiently rigid to be handled, transported, stored and exposed
even in the absence of an additional thick plastic support
structure, such as a tray.
SUMMARY
[0020] One or more embodiments of the presently disclosed subject
matter may address one or more of the aforementioned problems. In
an embodiment, a multi-compartment tray-less package having at
least two products in stack are contained into individual
compartments wherein each compartment is comprised between two
internal films, or an internal film and an outermost film. The
films may be peelable. The films comprise a crystallizable polymer.
The package further comprises a continuous rigid frame obtained by
partial heat-induced crystallization of the crystallizable polymer
during the sealing operation. Such a package does not require any
supplemental tray, with the advantage of reducing overall costs and
lowering its environmental impact. The package shows several
advantages such as preventing drying of leftovers, maintaining
sterility, avoiding cross contamination among different products
etc . . . with a significantly reduced consumption of material
compared to conventional tray or backboard based multi-compartment
packages.
[0021] In an embodiment of the present invention a tray-less
multi-compartment package of individually sealed compartments
comprises [0022] i) two outermost films, [0023] ii) at least two
products in stack, [0024] iii) at least one internal film
interposed between the at least two products in stack, [0025] iv) a
peripheral circumferential continuous seal which seals the films in
stack together and delimits at least two sealed compartments in
stack, each compartment enclosing at least a product of said at
least two products in stack, characterized in that the films
comprise a crystallizable polymer and the crystallizable polymer is
at least partially crystallized in correspondence of the sealing
area thus providing a peripheral circumferential continuous rigid
frame.
[0026] Another embodiment of the present invention is a method for
manufacturing the multi-compartment package, such a method
comprising the steps of: [0027] i) providing two outermost and at
least one internal, optionally pre-cut, crystallizable films;
[0028] ii) providing at least two products to be packaged; [0029]
iii) stacking an outermost film, the product(s), the internal
film(s)--alternating the products and the internal film(s)--and the
other outermost film, up to the desired number of compartments is
obtained; [0030] iv) sealing and simultaneously crystallizing the
stack of films along a peripheral circumferential continuous
sealing area thus providing a peripheral circumferential continuous
rigid frame, and [0031] v) optionally, simultaneously or
afterwards, cutting the stack of films all around outside the frame
thus providing the multi-compartment package; or, alternatively the
steps of: [0032] a) providing two outermost and at least one
internal, optionally pre-cut, crystallizable films; [0033] b)
providing at least two products to be packaged; [0034] c) placing
in stack an outermost film, a product and an internal film; [0035]
d) sealing and simultaneously crystallizing the stack of films
along a peripheral circumferential continuous sealing area thus
providing a peripheral circumferential continuous rigid frame;
[0036] e) optionally, simultaneously or afterwards, cutting the
stack of films all around outside the frame thus providing the
first compartment of the package; [0037] f) placing a stack of "a
product/a film" or of "a film/a product/a film", onto the
compartment formed in steps c) to e); [0038] g) repeating point d)
to f) for each new compartment, up to the desired number of
compartments is obtained, thus providing the multi-compartment
package; or, alternatively the steps of [0039] A) providing two
outermost and at least two internal, optionally pre-cut,
crystallizable films; [0040] B) providing at least two products to
be packaged; [0041] C) placing in stack a film, a product and a
film; [0042] D) sealing and simultaneously crystallizing the stack
of films along a peripheral circumferential continuous sealing area
thus providing a peripheral circumferential continuous rigid frame;
[0043] E) optionally, simultaneously or afterwards, cutting the
stack of films all around outside the frame thus providing the
first compartment of the package; [0044] F) manufacturing at least
another compartment following steps A to E; [0045] G) stacking the
first and the new compartment(s), optionally placing a product in
between adjacent compartments; [0046] H) sealing or gluing together
the first and the other new compartment(s), simultaneously or one
after the other if more than two, up to the desired number of
compartments is obtained, thus providing the multi-compartment
package.
Definitions
[0047] As used herein the term "tray-less package" refers to a
package in which a rigid tray, container, receptacle, backing
board, plate, and equivalent rigidity-conferring support commonly
used in the packaging field, placed outside the sealed compartments
and to which the films are connected (i.e. sealed, glued etc.), is
absent. The term "tray-less package" does not exclude the presence
of pads or other flexible, semi-rigid or rigid supports enclosed
within one or more of the sealed compartments (i.e., does not
exclude a completely enclosed support) where the enclosed support
is not sealed together with the films in stack but is completely
enclosed within the sealed compartment. Similarly, the term
"tray-less package" does not exclude that the present package may
be further placed into a container, providing that it is not
connected to it by circumferential sealing, gluing etc.
[0048] As used herein the term "multi-compartment package" refers
to a package having more than one compartment in stack. This
package contains more than one portion and/or more than one item of
one or more products in stack, each portion and/or each item being
enclosed in an individually sealed compartment.
[0049] As used herein the terms "compartment" and "sealed
compartment" refer to a part of the present package delimited by
two adjacent films--i.e. two internal films or an internal film and
a outermost film--sealed together along a peripheral
circumferential continuous seal. Each compartment encloses at least
a product.
[0050] As used herein in conjunction with a compartment, the term
"outermost film" refers to a plastic film positioned closest to the
outside of the package relative to the internal films wherein one
of the surfaces of an outermost film is in contact with a product
and the other surface of the outermost film is not.
[0051] As used herein the term "product(s)" refers to both
countable and uncountable products. In case of countable products,
the term "products" refers to at least two items of said product(s)
while in case of uncountable products, it refers to at least two
portions.
[0052] As used herein the term "two products" refers to two items
or portions of products packaged in the present package. The "two
products" maybe the same or different. If the two products are the
same, the package contains either two items or two portions of that
same product.
[0053] As used herein the term "single portion of product" refers
to an amount of product which is contained in a compartment of the
package.
[0054] Any arrangement of the one or more portions and/or items of
the one or more product(s) in the sealed compartments of the
present multi-compartment package is intended to be within the
scope of the presently disclosed subject matter--i.e. different
items or portions of one product, each one singularly enclosed in a
sealed compartment such as sterilized bandages or slices of ham;
different items or portions of two or more products each one
singularly enclosed in a sealed compartment such as slices of
cheese/slices of ham/slices of salami each one packaged in a
different compartment; different items or portions of a single
product, more than one item or portion being enclosed in a sealed
compartment such as two sterilized patches in the same compartment;
different items or portions of two or more products, more than one
item or portion of different products being enclosed in the same
compartment such as a sterilized bandage and a plaster together in
the same compartment etc.
[0055] As used herein the term "internal film" refers to a plastic
film of the package wherein one of its surface is in contact with
the product(s) enclosed in a first compartment and the other
surface is in contact either with the product(s) of a second
compartment or with the surface of another internal film.
[0056] As used herein, the term "film" includes flexible plastic
webs, regardless of whether it is a film or a sheet or a laminate.
Typically, the film used in the package object of the presently
disclosed subject matter has a thickness from 100 .mu.m to 5 .mu.m;
more preferably from 60 .mu.m to 7 .mu.m, even more preferably from
40 .mu.m to 10 .mu.m.
[0057] The outer films and the internal film(s) may have the same
thickness, however they may also be of different thickness.
[0058] As used herein, the phrase "which seals the films in stack
together" when referred to the peripheral circumferential
continuous seal means that all or, in alternative, some of the
films in stack are sealed together while some others may be
glued.
[0059] In case only some of the films are sealed together, the
package may be assembled by stacking the sealed compartments and by
gluing them together, as described for instance in a third variant
of the manufacturing process of the present package. In such a
case, the crystallinity induced in the sealing area of each single
independent compartments is sufficient to confer a suitable
rigidity to the final frame after assembly of the package by
gluing.
[0060] As used therein, the term "frame" means the rigid peripheral
circumferential continuous partially crystallized edge obtainable
by sealing the outermost and internal plastic film(s) of the
package to each other in stack.
[0061] As used herein the term "rigid" refers to the flexural
rigidity of the frame. Independently of the test method adopted to
evaluate the rigidity of the frame, in the present contest "rigid"
means that the frame obtained by sealing the outermost and internal
plastic film(s) of the package to each other in stack has a
rigidity higher than the rigidity of the same stack of outermost
and internal plastic film(s) before sealing.
[0062] Flexural resistance to bending can be measured for instance
by Dynamic Mechanical Analysis (DMA) according to ASTM 4065 or with
a dynamometer in line with ASTM D790 and can be expressed in
N/m.sup.2 as resistance of the frame to bending.
[0063] Rigidity requirements of the present package may change
depending on the products packaged, its final use and destination
etc. However the skilled person is able to select both
crystallizable polymer(s) and optimal sealing conditions in order
to impart to the package the stiffness required by the intended
use.
[0064] The stack of outermost and internal plastic film(s) before
sealing is rather flexible. After sealing, the at least partial
crystallization of the films induced by heat and pressure in
correspondence of the sealing area, forms the frame and imparts a
rigidity which is higher than the rigidity of the starting stack of
films. The frame, depending on the level of crystallization
induced, on the thickness and width of the sealing area etc., may
still be partially flexible or semi-rigid, but it has to be
understood that its rigidity is always higher than the rigidity of
the starting stack of films before sealing.
[0065] As used herein, the term "sealing" refers to the bonding of
plastic films obtainable by application of all those sealing
techniques which are able to induce an at least partial
crystallization of the crystallizable polymer(s) of the films along
the sealing area, such as for instance hot bar sealing or
ultrasonic welding techniques.
[0066] As used herein, the terms "crystallizable", when referred to
polymers, plastic films or sheets, means that the polymer, the film
or sheet comprising the polymer can crystallize under sealing
conditions, e.g. upon heating and/or compression.
[0067] As used herein, the terms "crystallized or crystalline"
polymer, resin, polyester etc. refer to homopolymers and
copolymers, compounded formulations or recyclates, having a
definite melting temperature.
[0068] As used herein, the term "crystallizable polymer(s)" refers
to polymer, homopolymers, copolymers, blends, compounded
formulations or recyclates, resins, etc able to crystallize at the
sealing conditions adopted during the sealing step. Examples of
suitable crystallizable polymers are crystallizable
polypropylene(s) homo- or copolymers, high density polyethylenes
(HDPEs), medium density polyethylenes (MDPEs), polyesters,
biodegradable polyesters such as polylactic acids (PLAs),
polyamides such as PA6, preferably added with nucleating agents,
polystyrenes (PS), more preferably crystallizable polyesters, and
their blends. As used therein, the expressions "polymer or
polypropylene or polyethylene or polyester (based)", when referred
to the film or film composition means that the film is a mono- or
multilayer film comprising at least 30% by weight, with respect to
the total weight of the film, of a crystallizable polymer or
polypropylene or polyethylene or polyester, preferably of a
crystallizable polyester, more preferably at least 50%, 60%, 70%,
80%, 90% or 95%.
[0069] When the crystallizable polymer is for instance a polyester,
with the term "crystallizable polyester" a polyester able to
crystallize at temperatures typically ranging from 140.degree. C.
to 220.degree. C.--temperatures generally adopted in the sealing
stage of the manufacturing process--is meant.
[0070] As used herein the phrase "the polymer is at least partially
crystallized" refers to a polymer which is at least partially
crystalline. As used herein the phrase "at least partially
crystalline polymer" refers to a polymer, for example a polyester,
which has a percentage of crystallinity higher than 15%, preferably
higher than 20%, more preferably higher than 25%, even more
preferably higher than 30%.
[0071] The melting temperature of the polymer(s) and their
crystallinity can be evaluated by Differential Scanning Calorimeter
(DSC) or by other equivalent procedures well known in the art.
[0072] For instance, DSC may be used to determine the degree of
crystallinity of thermoplastic polymers through the measurement of
the enthalpy of fusion (measurable following ASTM E793) and its
normalization to the enthalpy of fusion of a 100% crystalline
polymer (see B. Wunderlich, Thermal Analysis, Academic Press, 1990,
pp. 417-431).
[0073] In the present context, the crystallinity of the
crystallizable polymer(s) before the sealing step is substantially
uniform across the whole film(s). However in the final package
according to the presently disclosed subject matter the
crystallinity of the crystallizable polymer in correspondence of
the sealing area, i.e. in correspondence of the frame, is higher
than the crystallinity of the same polymer in areas other than the
sealing area.
[0074] "Higher than the crystallinity of the same polymer in areas
other than the sealing area" means that the difference in the
percentage of crystallinity of the polymer(s) of the frame with
respect to the polymer(s) of the other parts of the present package
is at least 5% preferably higher than 8%, more preferably higher
than 10%
[0075] As used herein, the phrases "seal layer", "sealing layer",
"heat seal layer", and "sealant layer", refer to an outer layer
involved in the sealing of the film to itself, to another film
and/or to another article which is not a film.
[0076] As used herein the term "peelable", referred to a film or a
sheet means that the films sealed to each other provide for a seal
which is strong enough to guarantee the hermeticity of the package
during its lifecycle but which can be easily opened by tearing
apart by hand the two films that were joined by the seal.
[0077] In the presently disclosed subject matter when peelable
films are used, each peelable film is capable of forming a seal,
under the application of heat and/or pressure, to a surface layer
of another film of the package and the seal is breakable without
fracture of the film. A method of measuring the strength of a
peelable seal, also referred to as "peel strength" is described in
ASTM F-88-00. Acceptable peel strength values generally range from
200 g/25 mm to 850 g/25 mm, from 300 g/25 mm to 830 g/25 mm, from
350 g/25 mm to 820 g/25 mm, from 400 g/25 mm to 800 g/25 mm.
[0078] As used herein, "EVOH" refers to ethylene/vinyl alcohol
copolymer. EVOH includes saponified or hydrolyzed ethylene/vinyl
acetate copolymers with a degree of hydrolysis preferably at least
50%, and more preferably, at least 85%. Preferably, the EVOH
comprises from about 28 to about 48 mole % ethylene, more
preferably from about 32 to about 44 mole % ethylene.
[0079] As used herein, the phrase "machine direction", herein
abbreviated "MD" or longitudinal direction "LD", refers to a
direction "along the length" of the film, i.e., in the direction of
the film as the film is formed during extrusion and/or coating.
[0080] As used herein, the phrase "transverse direction", herein
abbreviated "TD", or crosswise direction refers to a direction
across the film, perpendicular to the machine or longitudinal
direction.
[0081] As used herein, the phrases "orientation ratio" and
"stretching ratio" refer to the multiplication product of the
extent to which the plastic film material is expanded in the two
directions perpendicular to one another, i.e. the machine direction
and the transverse direction. Thus, if a film has been oriented to
three times its original size in the longitudinal direction (3:1)
and three times its original size in the transverse direction
(3:1), then the overall film has an orientation ratio of 3'3 or
9:1.
[0082] As used herein, the phrases "heat-shrinkable,"
"heat-shrink," and the like, refer to the tendency of the film to
shrink upon the application of heat, i.e., to contract upon being
heated, such that the size of the film decreases while the film is
in an unrestrained state.
[0083] As used herein, the phrases "low heat-shrinkable," "low
heat-shrink" or simply "low shrink films" and the like, refer to
films with a free shrink in both machine and transversal
directions, as measured by ASTM D 2732, lower than 10% at 140
.degree. C., more preferably lower than 5%.
[0084] As used herein, the term "polymer" refers to the product of
a polymerization reaction, and is inclusive of homo-polymers and
co-polymers.
[0085] As used herein, the term "homopolymer" is used with
reference to a polymer resulting from the polymerization of a
single monomer, i.e., a polymer consisting essentially of a single
type of mer, i.e., repeating unit.
[0086] As used herein, the term "copolymer" refers to polymers
formed by the polymerization reaction of at least two different
monomers. The term "copolymer" is inclusive of terpolymers, random
co- or terpolymers, block co- or terpolymers, and graft co- or
terpolymers.
[0087] As used herein, the term "polyolefin" refers to the polymer
or co-polymer resulting from the polymerisation or
co-polymerisation of unsaturated aliphatic, linear or cyclic,
straight or branched, hydrocarbon monomers that may be substituted
or unsubstituted. More specifically, included in the term
polyolefin are film-forming homo-polymers of olefin, co-polymers of
olefin, co-polymers of an olefin and an non-olefinic co-monomer
co-polymerizable with the olefin, such as vinyl monomers, and the
like. Specific examples include polyethylene homo-polymer,
polypropylene homo-polymer, polybutene homo-polymer,
ethylene-alpha-olefin co-polymer, propylene-alpha-olefin
co-polymer, butene-alpha-olefin co-polymer, ethylene-unsaturated
ester co-polymer, ethylene-unsaturated acid co-polymer, (e.g.,
ethylene-(C.sub.1-C.sub.4)alkyl acrylate or methacrylate
copolymers, such as for instance ethylene-ethyl acrylate
co-polymer, ethylene-butyl acrylate co-polymer, ethylene-methyl
acrylate co-polymer, ethylene-methyl methacrylate co-polymer,
ethylene-acrylic acid co-polymer, and ethylene-methacrylic acid
co-polymer), ionomer resin, polymethylpentene, etc.
[0088] For the purpose of the present description and of the claims
which follow, except where otherwise indicated, all numbers
expressing amounts, quantities, percentages, and so forth, are to
be understood as being modified in all instances by the term
"about".
BRIEF DESCRIPITION OF DRAWINGS
[0089] FIG. 1 is a top view of a the package 1 of an embodiment of
the presently disclosed subject matter, the package being provided
with a tab (4) for the easy peeling of the film(s).
[0090] FIG. 2a is a cross section view of a first embodiment (1A)
of the package of FIG. 1.
[0091] FIG. 2b is a cross section view of a second embodiment (1B)
of the package of FIG. 1.
[0092] FIGS. 3A-3B and 3C-3E are other cross-section views of the
first (1A) and second embodiment (1B) illustrated in FIGS. 2a and
2b.
[0093] FIG. 4 is a perspective view of another embodiment of the
package of presently disclosed subject matter, the package being
provided with an aperture (7) allowing vertical displaying of the
package.
[0094] FIG. 5 is a perspective view of still another embodiment of
the package of presently disclosed subject matter, the package
being provided with a hook (8) for vertical display of the
package.
[0095] FIGS. 6A to E show the profile of some sealing bars suitable
for the manufacture of the present package.
[0096] FIGS. 7A and 7B illustrate a first method for manufacturing
embodiment 1A and, respectively, embodiment 1B of a three
compartment package according to the presently disclosed subject
matter.
[0097] FIGS. 8A and 8B illustrate a second method for manufacturing
embodiment 1A and, respectively, embodiment 1B of a three
compartment package according to the presently disclosed subject
matter.
[0098] FIGS. 9A and 9B illustrate a third method for manufacturing
embodiment 1A and, respectively, embodiment 1B of a three
compartment package according to the presently disclosed subject
matter.
DETAILED DESCRIPTION
[0099] An embodiment of the presently disclosed subject matter is a
tray-less multi-compartment package of individually sealed
compartments comprising [0100] i) two outermost films, [0101] ii)
at least two products in stack, [0102] iii) at least one internal
film interposed between the at least two products in stack, [0103]
iv) a peripheral circumferential continuous seal which seals the
films in stack together and delimits at least two sealed
compartments in stack, each compartment enclosing at least a
product of said at least two products in stack, characterized in
that the films comprise a crystallizable polymer and the
crystallizable polymer is at least partially crystallized in
correspondence of the sealing area, thus providing a peripheral
circumferential continuous rigid frame.
[0104] The present package is a multi-compartment package
comprising at least two compartments in stack, each compartment
comprising at least a portion or a item of at least one
product.
[0105] In one embodiment, the present package is a bi-portion
package comprising two compartments in stack.
[0106] In another embodiment the present package is a more than two
i.e. tri- or more-portion package comprising more than two
compartments in stack.
[0107] The total number of compartments depends, inter alia, on the
thickness of the product contained, i.e. the greater is the
thickness of the product and the lower is the number of
compartments of the package object of the presently disclosed
subject matter.
[0108] Internal plastic films are positioned between two subsequent
portions of product(s) in the stack and are sealed, for example
peelably sealed, to each other along the frame. In one embodiment,
the packages are advantageously provided with a tab facilitating
the opening.
[0109] In one embodiment of the multi-compartment package of the
presently disclosed subject matter (embodiment 1A), only one
internal film (6) is interposed between two adjacent products
(2).
[0110] In this embodiment (1A), each internal film is in common
between two adjacent compartments (as shown in FIG. 2A for a
bi-compartments package) and the removal, one after the other, of
the films--i.e. first an outer film and then the next internal
film(s)--provides for the direct opening of each compartment.
[0111] In the embodiment 1A, in which two adjacent portions or
items of same or different products share a single internal plastic
film, the package is obtained by alternating the films and the
products to be packaged in this order, up to the desired number of
compartments is obtained.
[0112] In another embodiment of the multi-compartment package of
the presently disclosed subject matter (embodiment 1B), as
represented in FIG. 2B, two internal films (6) are interposed
between two adjacent products.
[0113] In the embodiment 1B, two adjacent portions/items of
product(s) are completely enclosed by their own films. It is thus
possible for the user to detach each single sealed compartment
separately but keeping the different portions still packaged. Each
single compartment may thus be opened and the product used when and
where desired.
[0114] A package object of the presently disclosed subject matter
generally comprises from 2 to 20 compartments, for example from 2
to 10, also for example from 2 to 5.
[0115] The number of films required for the package according to
the presently disclosed subject matter may range from at least n+1
to at most 2n, being n the number of compartments desired.
[0116] For the range of compartments from 2 to 10, the package may
comprise from 3 to 20 films.
[0117] According to a first method embodiment of the presently
disclosed subject matter, the films can be hermetically sealed to
each other by a single sealing step at the end of the stacking
operation with an appropriate sealing bar which induces the partial
crystallization of the sealing area, as represented in FIGS. 7A and
7B.
[0118] When suitably shaped, the sealing bar may also thermoform
the sealing area, thus further increasing the rigidity of the
frame. In case a sealing bar with a thermoforming profile is used,
films with lower orientation ratios may be selected.
[0119] In another embodiment, a first sealed compartment,
containing the product, can be added with alternated product/film
or film/product/film sequences in stack, each new added sequence
being sealed progressively, as represented in FIGS. 8A and 8B.
[0120] In another embodiment, each compartment comprising two films
and a portion of product may be sealed separately and then, the
stacked compartments, sealed/glued together in subsequent steps, as
represented in FIGS. 9A and 9B.
[0121] The internal plastic film(s) (6) and the outermost plastic
films (5) of the package according to an embodiment of the
presently disclosed subject matter are sealable and peelable films
which allow the easy opening of each compartment and/or the easy
detachment of each single compartment. The peelable films may
comprise a peelable coating or a peelable sealant.
[0122] The outermost films and the internal film(s) used in the
present package may be the same or different.
[0123] The outermost films used in a package embodiment of the
presently disclosed subject matter may be transparent, opaque,
colored by pigment additives or may have printing thereon or
stickers or labels depending on the desired end use.
[0124] One of the two outermost films (5) may be printed; in this
case the packaging machine can house two rolls: one for the printed
outermost film and the other for the non-printed films of the
package. Alternatively, the machine can be provided with an in-line
printing system, as those commercialised for example by DIGI and a
second roll of material is not needed.
[0125] The internal films (6) of the film used in a package
embodiment of the presently disclosed subject matter may be
transparent.
[0126] The film used in an embodiment of the presently disclosed
subject matter may have a thickness of any of from 100 .mu.m to 5
.mu.m; from 60 .mu.m to 7 .mu.m, and from 40 .mu.m to 10 .mu.m.
[0127] The multi-compartment packages allow for a significant
reduction of packaging material with respect to the weight of the
product packaged therein.
[0128] Accordingly, in the present multi-compartments package, the
ratio between the weight of the packaging material (i.e. the total
weight of the films) (B) with respect to the total weight of the
package (A), calculated as percentage by weight, according to the
following formula: (B)/(A).times.100, may be lower than 15%, for
example, lower than 10%, or lower than 7%.
[0129] In the prior art multi-compartment packages--in which a tray
or a backboard is present--said ratio is significantly higher, as
more than 15%, typically more than 20%.
[0130] The shape of the frame and that of the (pre)-cut films
according to the presently disclosed subject matter are not
limited. For example they can independently be rectangular, round,
oval, triangular or in general polygonal or they can follow the
shape of the packaged product, thus having a better pack appearance
and becoming more attractive for the consumer.
[0131] The package (1) can have for example a rectangular shape as
showed in FIG. 1. Each portion of the product (2) is enclosed in a
respective sealed compartment. The sealing step provides the
package with a rigid frame (3) formed by the superimposed and
heat-crystallized films.
[0132] According to an embodiment of the disclosed subject matter,
the package is advantageously provided with a tab (4) for the easy
peeling of the film(s).
[0133] FIGS. 2a and 2b show cross section views along the line A-A
of the package of FIG. 1 representing two different embodiments (1A
and 1B), each one comprising two outer films (5) and one or two
internal films (6) respectively. In particular FIG. 2a illustrates
embodiment 1A in which only one internal film is interposed between
the two products in stack while FIG. 2b illustrates embodiment 1B
in which two films are interposed.
[0134] FIGS. 3A-3B and 3C-3E show the mechanism of opening of the
packages illustrated under FIGS. 2A and 2B, in particular, they are
cross-section views along the diagonal line B-B of said packages as
disclosed in FIG. 1.
[0135] FIGS. 3A-3B show the opening of the package 1A having a
single internal film (6) (embodiment A). By pulling one of the
outermost films in correspondence of the tab (4), the respective
compartment is directly opened and the content exposed for prompt
use while the remaining package is still sealed.
[0136] FIGS. 3C-3E show the opening of the package 1B having of two
internal films (6) (embodiment B). By pulling together one of the
outermost films (5) and the adjacent internal film (6) in
correspondence of the tab (4), the respective sealed compartment is
detached: both the compartments are still sealed and the content
still packaged in independent packages for a later use.
[0137] According to a further embodiment of the disclosed subject
matter shown in FIG. 4 the package is advantageously designed such
as to have an aperture (7) allowing hanging up the package to a
vertical display.
[0138] According to another embodiment of the disclosed subject
matter shown in FIG. 5 the package is advantageously designed such
as to have a hook (8) allowing to hang up the package to a vertical
display.
[0139] Those skilled in the art know tools, equipment and
techniques to obtain such sealing shapes or hooks or apertures in
the package and to provide it with a tab facilitating its
opening.
[0140] In a package embodiment of the presently disclosed subject
matter the compartments may be filled with a modified atmosphere.
Modified atmosphere packaging (MAP) is a technique used for
prolonging the shelf-life of perishable goods. MAP packages
according to the presently disclosed subject matter may be
manufactured following methods known in the art, such as
"gas-flushing" and "compensated vacuum".
[0141] In another embodiment, the compartments of the present
multi-compartment package are under vacuum, thus advantageously
extending the shelf-life of the enclosed perishable food products
(vacuum packaging). In that case, air is removed from the
compartments before sealing, then the compartments are hermetically
sealed without any gas flushing or compensation.
[0142] In a package embodiment of the presently disclosed subject
matter, the films comprise crystallizable polymer(s), namely
polymer(s), homopolymer(s), copolymer(s), blends, compounded
formulations or recyclates, resins which can crystallize at the
sealing conditions adopted during the sealing step, i.e. upon
heating and/or compression.
[0143] Crystallizable polymers are for instance crystallizable
polypropylene(s) homo- or copolymers, high density polyethylenes
(HDPEs), medium density polyethylenes (MDPEs), polyesters,
biodegradable polyesters such as polylactic acids (PLAs),
polyamides such as PAG, preferably added with nucleating agents,
polystyrenes (PS), more preferably crystallizable polyesters, and
their blends.
[0144] The amount of the crystallizable polymer in the films of the
present package with respect to the total weight of the films is at
least 30% by weight, for example any of at least 50%, 60%, 70%,
80%, 90% or 95%.
[0145] The package according to an embodiment the presently
disclosed subject matter comprises polyester-based films each one
having the same thickness and composition. In alternative, the
films of the present package may be of different thickness and/or
composition.
[0146] The crystallizable polyester resins that may be used for the
presently disclosed subject matter are able to crystallize upon
heating, i.e. at temperatures--typically ranging from 140.degree.
C. to 220.degree. C.--generally adopted in the sealing stage of the
manufacturing process.
[0147] Crystallizable polyester resins preferably used for the
presently disclosed subject matter are able to crystallize under
heating and/or under compression--e.g. by setting the sealing
machine at temperatures typically ranging from 140.degree. C. to
220.degree. C., preferably 170 to 200.degree. C. and/or at a
pressure generally ranging from 2 to 8 bar, preferably 4 to 7
bar--temperature and pressure settings generally adopted in the
sealing stage of the manufacturing process.
[0148] The films are mono- or multilayer films, and may be peelable
films, each comprising at least 30% by weight, with respect to the
total weight of the film, of a crystallizable polyester resin
preferably at least 50%, 60%, 70%, 80%, 90% or 95%.
[0149] In the film suitable for the package according to an
embodiment of the presently disclosed subject matter, the
percentage of crystallinity of the crystallizable polymer, for
example of the crystallizable polyesters and/or copolyesters, will
be higher than 15%, for example higher than any of 20%, 25%, and
30% in correspondence of the sealing area, after the sealing
step.
[0150] The percentage of crystallinity of the polyesters and
co-polyesters suitable for embodiments of the disclosed subject
matter is evaluated by Differential Scanning Calorimetry (DSC), as
known in the art (see B. Wunderlich, Thermal Analysis, Academic
Press, 1990, pp. 417-431).
[0151] Polyesters are polymers containing ester groups in their
backbone chain obtained from the reaction of a diol with a diacid.
In homopolyesters only one species of diol and of diacid are
employed, while in co-polyesters at least one of the carboxylic
acids or of the diols is used in combination of at least two
species.
[0152] Suitable crystallizable polyesters for the films of the
present package include homo-polyesters, such as poly(ethylene
terephthalate), poly(ethylene 2,6-naphthalate), poly(1,2-propylene
terephthalate), poly(ethylene 2,5-dimethyl-terephthalate),
poly(butylene terephthalate), poly(ethylene isophthalate),
poly(ethylene 5-t-butyl-isophthalate), poly(butylene
2,6-naphthalate), and the like homopolymers, and co-polyesters
where the diacid component is still mainly based on aromatic
diacids such as terephthalic acid, isophthalic acid, alkyl
substituted-terephtahlic acid, alkyl-substituted isophthalic
acid.
[0153] Suitable crystallizable homo-polyester and co-polyester
resins are typically characterized by a high melting point (Tm),
such as a Tm higher than 220.degree. C., preferably higher than
230.degree. C.
[0154] Specific examples include Eastapak Copolyester 9921 sold by
Eastman and Ramapet N180 sold by Indorama.
[0155] Crystallizable biodegradable polyester resins can also be
used. Examples of crystallizable biodegradable polyesters are:
polyglycolide (PGA) and its copolymers with caprolactone, lactide
or trimethylene carbonate, polylactide (PLA),
poly(lactide-co-glycolide) (PLGA), Poly(butylene succinate) (PBS)
and poly(ethylene succinate), poly(butylene adipate-co-terephtalate
(PBAT). A suitable PLA is commercialized for example under the
trade name of NatureWorks.RTM. by CargillDow. A suitable PBAT is
sold as Ecoflex.RTM. by BASF, Eastar Bio.RTM. by Eastman Chemical,
Origo-Bi.RTM. by Novamont.
[0156] A multi-compartment package according to the presently
disclosed subject matter substantially made of crystallizable
biodegradable polyester(s) will be even more eco-friendly.
[0157] Polyesteramides may also be used such as those
commercialized by Bayer under the trade name BAK.RTM..
[0158] The crystallizable polymers films suitable for the package
according to an embodiment of the presently disclosed subject
matter may consist of two layers, a base layer and a sealing
layer.
[0159] The crystallizable polymers may be crystallizable polyester
resins. Suitable crystallizable polyester resins for the base layer
are those described before.
[0160] In an embodiment, the crystallizable polyester resin of the
base layer is blended with an amorphous polyester resin. Said
amorphous polyester is characterized by a Tg value lower than
115.degree. C., preferably lower than 95.degree. C., even more
preferably lower than 85.degree. C.
[0161] The amount of said amorphous polyester in the base layer of
the film of the present package is generally at most 70% by weight
with respect to the total weight of the base layer, for example at
most any of 50% and 40% by weight.
[0162] Suitable amorphous polyester resins are those deriving from
an aliphatic diol and/or a cycloaliphatic diol with one or more
dicarboxylic acids, preferably an aromatic dicarboxylic acid.
Preferred amorphous polyesters are copolyesters of terephthalic
acid with an aliphatic diol and a cycloaliphatic diol, particularly
ethylene glycol and 1,4-dicyclohexanedimethanol. The preferred
molar ratios of the cycloaliphatic dial to the aliphatic diol are
in the range from 10:90 to 60:40, preferably in the range from
20:80 to 40:60, more preferably from 30:70 to 35:65. Specific
examples of particularly preferred amorphous polyester are PETG
Eastar.RTM. 6763, sold by Eastman (glass transition temperature
81.degree. C., density 1.27 g/cc) and Embrace sold by Eastman
Chemical, (glass transition temperature 70.6.degree. C., density
1.32 g/cc).
[0163] In another embodiment, the whole film or, if present, said
base layer will comprise one or more suitable crystallizable home-
and/or co-polyesters blended with up to preferably about 10% of a
masterbatch containing conventional additives dispersed in a
(co)polyester matrix, additives known in the art as nucleating
agents, which favor the crystallization process during the sealing
step.
[0164] Suitable nucleating agents are for instance those listed in
Table 1 of the Literature Review by H. Zhou available at the
internet address www.crd.ge.com as 98CRD138. Particularly preferred
nucleating agents are inorganic compounds such as talc, silicate,
clay, titanium dioxide, and the like. These compounds may be used
in an amount lower than 5% by weight, typically in an amount of
1-2% by weight on the total weight of the film or base layer. Other
preferred nucleating agents are certain compatible polymers such as
fluoropolymers (PTFE) that can be blended with the polyester of
said film or layer (a) in an amount of up to e.g. 5-8% by
weight.
[0165] Examples of nucleating agents particularly suitable for
crystallizing polyesters which can be used in the present
application are: (i) alkali metal salts of organic acids, e.g.
carboxylic acid; sodium, lithium, potassium benzoates (see D.
Garcia, Heterogeneous nucleation of PET, J. of Polymer
Science--Polymer physics edition, Vol 22, 2063-2072, 1984 and R.
Legras, C. Bailly, M. Daumerie, V. Zichy and others, Chemical
nucleation, a new concept applied to mechanism of action of organic
acid salts on the crystallization of PET and
bisphenol-A-polycarbonate, Polymer, Vol 25, 835-844, 1984) or
sodium salts of substituted benzoic acids which contain at least
one nitro, halogen, hydroxyl, phenyl or oxyphenyl substituent, and
salts of alkali metals including phenolic, phosphonic, phosphinic
and sulfonic (see EP0021 648); (ii) lithium and/or sodium salts of
aliphatic, cycloaliphatic, aromatic carboxylic acids or
heterocyclic polycarboxilic acids, containing up to 20 carbon atoms
(see U.S. Pat. No. 3,761,450); (iii) DBS-dibenzylidene sorbitol
(see J. of Applied Polymer Science, Vol 36, 387-402, 1988); (iv)
trygliceride oil and triglyceride oil in combination with/or
chemically bonding to organic acid metal salts (see U.S. Pat. No.
5,356,972). Nucleating agent that may be used in the presently
disclosed subject matter are commercially available as Tna 5471 by
Sukano, Elvaloy PTW and Elvaloy AC by Dupont, Hyperform HPN series
by Milliken.
[0166] Examples of nucleating agent that can be used in the
presently disclosed subject matter suitable for crystallizing
polypropylenes are the compounds supplied by Milliken under the
trade name of Millad.
[0167] The amount of nucleating agent generally depends on the type
of polymer used. According to the conventional practice, the
nucleating agent is generally used in an amount of from 2% to 5%,
more preferably from 2.5% to 4%, even more preferably of about
3%.
[0168] Preferably the nucleating agents have a particle size not
higher than 10 microns.
[0169] The base layer may have a thickness between about 10 and 90
.mu.m, more preferably between about 15 and 60 .mu.m, even more
preferably between about 20 and 35 .mu.m.
[0170] The heat-sealable layer can comprise at least a first
amorphous polyester resin and optionally a further polyester
resin.
[0171] The amorphous polyester is characterized by a Tg value lower
than 115.degree. C., for example lower than 95.degree. C. or lower
than 85.degree. C. Suitable amorphous polyester resins are those
deriving from an aliphatic diol and a cycloaliphatic dial with one
or more dicarboxylic acids, for example an aromatic dicarboxylic
acid. Amorphous polyesters may be copolyesters of terephthalic acid
with an aliphatic diol and a cycloaliphatic diol, particularly
ethylene glycol and 1,4-dicyclohexanedimethanol. The exemplary
molar ratios of the cycloaliphatic diol to the aliphatic diol are
in the range from 10:90 to 60:40, for example in the range from
20:80 to 40:60, or from 30:70 to 35:65. Specific examples of
amorphous polyester are PETG Eastar.RTM. 6763, sold by Eastman
(glass transition temperature 81.degree. C., density 1.27 Wee) and
Embrace sold by Eastman Chemical, (glass transition temperature
70.6.degree. C., density 1.32 g/cc).
[0172] A blend of two or more amorphous polyesters is also suitable
for the heat sealable layer of the films of the present
package.
[0173] Suitable further polyesters can be added in the sealant
layer. Such polyester can be those deriving from an aliphatic diol,
preferably ethylene glycol and one or more aromatic dicarboxylic
acid, preferably terephthalic acid.
[0174] Polyethylene terephthalate and its copolyesters may be used.
Specific examples include Eastapak Copolyester 9921 sold by Eastman
and Ramapet N180 sold by Indorama.
[0175] The amount of the first amorphous polyester in the
heat-sealable layer of the film of the presently disclosed package
may be at least 30% by weight with respect to the total weight of
the heat-sealable layer, for example at least 50% by weight, or at
least 60% by weight.
[0176] The amount of the further polyester in the heat-sealable
layer of the film of the present package is generally at most 70%
by weight with respect to the total weight of the heat-sealable,
for example at most 50% or at most 30% by weight.
[0177] In an embodiment, the internal film(s) (6) and the outermost
films (5) of the package according to an embodiment of the
presently disclosed subject matter are made of peelable films thus
allowing the easy opening of each compartment and/or its separation
from the others.
[0178] For example, the films may be peelable crystallizable
polyester-based films.
[0179] Peelability can be imparted to the films by admixing further
resins in the sealant layer, usually from 3 to 40% by weight, more
frequently 10 to 25% by weight of an appropriate thermoplastic
resin. Suitable thermoplastic resins that contribute to lowering
the sealing strength of a polyester sealant layer of a film are
polyethylens, polyamides, polystyrenes, in particular
styrene-butadiene block copolymers, ionomers, ethylene/unsaturated
carboxylic acid copolymers, like ethylene/(meth)acrylic acid
copolymers and ethylene/cyclic olefin copolymers, like
ethylene/norbornene copolymers. These resins have low compatibility
with the polyester resin layer and the resulting phase separation
confers the desired peelability. Specific examples are PRIMACOR
3440 by Dow, an ethylene/acrylic acid copolymer and Bynel 4104 by
Du Pont de Nemours, an anhydride-modified linear low-density
polyethylene (LLDPE).
[0180] The thickness of the heat-sealable layer is generally
between about 5 and 40% of the thickness of the base layer. The
heat-sealable layer may have a thickness of up to about 25 .mu.m,
for example up to about 15 .mu.m, or between about 0.5 and 10
.mu.m, or between about 0.5 and 7 .mu.m.
[0181] Additional layers can be present in the film of the
presently disclosed subject matter.
[0182] For example, an outer layer can be present, having a
thickness up to about 25 .mu.m, for example up to about 15 .mu.m,
or between about 0.5 .mu.m and 10 .mu.m, or between about 0.5 .mu.m
and 7 .mu.m. The outer layer is the outermost layer of the
structure.
[0183] The polyester resins suitable for the composition of the
outermost layer may be selected among the list of crystallizable
polyester resins reported above.
[0184] In an embodiment, the crystallizable polyester films useful
for the package according to the first object of the presently
disclosed subject matter comprise at least two layers: the sealant
and the base layer.
[0185] In an embodiment, the crystallizable polyester films
comprise at least three layers: the sealant, the base layer and the
outer layer.
[0186] In an embodiment, the same crystallizable polyester resin,
either alone or in blend, is used for the base and the outer layer.
Preferred resins are Eastapak Copolyester 9921 sold by Eastman and
Ramapet N180 sold by Indorama.
[0187] In an embodiment, the same amorphous polyester resin is used
in the base layer and in the sealant layer. Preferred resins are
PETG Eastar.RTM. 6763 sold by Eastman and Embrace sold by Eastman
Chemical.
[0188] In case of two or three layers films, the crystallizable
polyester may be present at a percentage in weight ranging from 50
to 70% with respect to the total weight of the film and the
amorphous polyester may be present at a percentage in weight
ranging from 25 to 35% with respect to the total weight of the
film.
[0189] The films of the present package can further comprise a
gas-barrier layer, which may be medium or high barrier to gases,
especially to oxygen, depending on the product to be packaged.
[0190] As used herein the term "medium barrier film" refers to a
film having an oxygen transmission rate (OTR) lower than 200
cc/sqm/day, preferably lower than 100 cc/sqm/day at 100% RH and
23.degree. C.
[0191] The multilayer film may comprise at least a high gas-barrier
layer and can exhibit an oxygen transmission rate (OTR) lower than
50, for example, lower than 30, or lower than 20 cc/m.sup.2day bar
at 23.degree. C. and 100% relative humidity.
[0192] The OTR of plastic films can be measured following ASTM
D3985.
[0193] Well-known gas-barrier resins and their blends suitable for
the barrier films include, for example, ethylene-vinyl alcohol
copolymers (EVOH), polyamides and acrylonitrile-based copolymers.
Once the gas-barrier resin has been selected, its thickness will be
set to provide for the desired permeability properties.
[0194] In the film, tie layers, to improve interlayer adhesion, may
be present. Tie layers may be disposed between the respective
layers in case where a sufficient adhesion is not ensured between
adjacent layers. The adhesive resin may preferably comprise one or
more polyolefins, one or more modified polyolefins or a blend of
the above. Specific, not limitative, examples thereof may include:
ethylene-vinyl acetate copolymers, ethylene-(meth)acrylate
copolymers, ethylene-alpha-olefin copolymers, any of the above
modified with carboxylic or preferably anhydride functionalities,
elastomers, and a blend of these resins.
[0195] One or more of the layers of the film of the presently
disclosed subject matter may contain any of the additives
conventionally employed in the manufacture of polymeric films.
Thus, agents such as pigments, lubricants, anti-oxidants, radical
scavengers, oxygen scavengers, UV absorbers, odour absorbers,
thermal stabilisers, anti-blocking agents, surface active agents,
slip aids, optical brighteners, gloss improvers, viscosity
modifiers may be incorporated as appropriate. In particular, to
improve the processing of the film in high speed packaging
equipment slip and/or anti-blocking agents may be added to one or
both of the outer layers. The additives may be added in the form of
a concentrate in a polyester carrier resin. As an alternative slip
agents may be added by coating, for instance by plasma coating or
by spraying (e.g. with a Weko equipment). The amount of additive is
typically in the order of 0.2 to 5% by weight of the total weight
of the layer.
[0196] In another embodiment, the films (5 and/or 6) of the present
package can be mono-layer films; in this case, suitable
crystallizable polyester resins, optionally blended to amorphous
polyesters, are the same--both in terms of kind and percentages--as
the ones for the base layer listed above.
[0197] The monolayers films suitable for the present packages are
sealable; and the monolayers films may also be peelable.
[0198] In order to impart the required peelability and sealability,
the films can be coated, either during or after their
manufacturing, with well known suitable compositions. Typical
coating composition and method are for examples described in
WO9619333, WO0154886, WO2011083342. The coating composition can be
applied to the film by any suitable conventional technique, for
example by spraying, dip coating, roll coating, bead coating,
reverse roller coating or slot coating, impregnation.
[0199] The grammage of the applied coating layer is typically in
the range from 0.1 to 5.0 g/m.sup.2, for example, any of from 0.3
to 3.0 g/m.sup.2, and from 0.5 to 2.0 g/m.sup.2. The thickness of
the coating layer is typically in the range from 0.3 to 10 .mu.m,
for example, from 0.5 to 5.0 .mu.m or from 1.0 to 2.0 .mu.m.
[0200] The coating can be applied onto one surface of the film or
onto both the surfaces. For films coated on both their surfaces,
the same ranges of grammage and thickness listed above are
applicable to each coating layer.
[0201] Before the deposition of the coating layer onto the film,
the surface to be coated may advantageously be subjected to a
chemical or physical treatment in order to improve the bond between
that surface and the applied coating layer. One of the preferred
treatments is to expose the surface to be coated to a high voltage
electrical stress accompanied by corona discharge. Alternatively,
the substrate may be pre-treated with an agent known in the art to
have a solvent or swelling action on the film. For example, for
polyester films, suitable agents include halogenated phenols
dissolved in an organic solvent, as a solution of
p-chloro-m-cresol, 2,4-dichlorophenol, 2,4,5- or
2,4,6-trichlorophenol or 4-chlororesorcinol in acetone or methanol.
Such coatings can also be applied to a multilayer film. In this
case there is no need to impart peelability to the film by
adding--in the sealant layers--resins having low compatibility with
the resin of the sealant layer.
[0202] The films of the presently disclosed package may be
low-shrink films as defined above. These films have no or
negligible shrink at temperatures below 140.degree. C. The shrink
(in each direction) is generally at most 15% at temperatures below
100.degree. C., below 120.degree. C., and even below 140.degree.
C.
[0203] Usually, in case of polyester based films, the shrink (in
each direction) does not exceed 15% over the common heat-sealing
temperature range of polyester films, namely in the range of from
140 to 200.degree. C. The shrink generally does not exceed 15% (in
each direction) at 180.degree. C., at 160.degree. C., and even at
150.degree. C.
[0204] Depending on the resins employed and on the particular final
application, these films can be manufactured by coextrusion,
extrusion coating, and/or lamination of preformed cast films,
followed by mono- or biaxial orientation and, optionally, by an
annealing or heat-setting step, or they may be prepared by
lamination of preformed films of which at least part of them have
been mono- or bi-axially oriented.
[0205] Typically, coextrusion equipment are used, where each resin
is extruded through an extruder and all the layers are joined into
the extrusion die. Typically, for polyester films, flat die is
used.
[0206] The film may be oriented. A tubular or flat film orientation
process can be used to produce a biaxially oriented film. The flat
film may be oriented with a tenterframe apparatus. In a tubular
process, also known as "double bubble" process, simultaneous
biaxial orientation is obtained by coextruding thermoplastic resins
in a tube shape which is subsequently quenched, reheated and then
expanded by internal gas pressure to induce transverse orientation,
and withdrawn at a rate which will induce longitudinal orientation.
An example of equipment suitable for this technique is disclosed by
U.S. Pat. No. 4,841,605. In alternative, a triple-bubble
orientation process may also be used, in such a case a final
relaxation or annealing step being included, as known in the art.
Another possible tubular process suitable for manufacturing the
films of the present package is the "hot blown" process.
[0207] In a flat film process, the film-forming thermoplastic
resins are extruded through a T-die and rapidly quenched upon a
chill roll to ensure that the resins are quenched to the amorphous
state. In order to improve the adhesion of the film on the chill
roll electrostatic pinning can be used, as known in the art and as
described in U.S. Pat. No. 5,494,619.
[0208] Orientation is then, optionally, effected by flat
stretching, simultaneously or sequentially, the quenched extrudate
at a temperature above the glass transition temperature of the
thermoplastic resins.
[0209] In the sequential flat orientation method a flat, quenched
extrudate is firstly oriented in one direction, usually the
longitudinal direction, i.e. the forward direction through the film
stretching machine, and then in the transverse direction.
Longitudinal stretching of the extrudate is conveniently carried
out over a set of rotating rolls (MDO), which rotate at different
speeds. At least one of the first pairs of rolls is heated, for
example by inner circulation of hot oil. Transverse stretching is
usually carried out in a tenter apparatus (TDO), which comprises a
certain number of heating zones and suitable stretching means.
[0210] To manufacture the multilayer films useful for the present
package, the polymers for the various layers are fed to separate
extruders. The melts are extruded through a multilayer T-die and
quenched over a chill roll. Longitudinal stretching (MDO) of the
extrudate is conveniently carried out at a temperature range from
60 to 120.degree. C., preferably from 70 to 100.degree. C. In the
transverse stretching (TDO), the temperatures of the film are in
the range from 90.degree. C. (preheating zone) to 130.degree. C.
(stretching zone), preferably from 90.degree. C. (preheating zone)
to 110.degree. C. (stretching zone). The longitudinal stretching
ratio is in the range from 2.0:1 to 5.0:1, preferably from 2.3:1 to
4.8:1. The transverse stretching ratio is generally in the range
from 2.4:1 to 6.0:1, preferably from 2.6:1 to 5.5:1.
[0211] In the simultaneous flat orientation method a flat, quenched
extrudate is simultaneously oriented in both the longitudinal and
in the transverse direction through a simultaneous tenter
apparatus.
[0212] The extrudate is fed to the pre-heating zone of a
simultaneous tenter apparatus, with or without a prior passage
through an IR heated oven. The temperature of the oven in said
pre-heating zone, the length thereof and the time spent by the
traveling web in said zone (i. e. the web speed) can suitably be
varied in order to bring the film up to the desired temperature for
bi-axial orientation. In a preferred embodiment the orientation
temperature is comprised between about 90.degree. C. and about
140.degree. C. and the temperature of the pre-heating zone is kept
between about 90.degree. C. and about 150.degree. C. In said
pre-heating zone the film is clipped but it is not yet stretched.
Thereafter, the resulting hot, optionally irradiated, and clipped
film is directed to the stretching zone of the simultaneous tenter.
Any simultaneous stretching means can be used in said zone.
Preferably however the clips are propelled throughout the opposed
loops of the tenter frame by means of a linear synchronous motor. A
suitable line for simultaneous stretching with linear motor
technology has been designed by Bruckner GmbH and advertised as
LISIM line. An alternative line for simultaneous stretching of the
extruded flat tape is the Andritz line, based on a pantograph,
equipped with two separated monorails on each side of the
orientation unit. The configuration of the tenter can be varied
depending on the stretching ratios desired.
[0213] The temperature in the stretching zone is kept close to the
selected orientation temperature. In case, annealing is carried out
at a temperature of from 130 to 220.degree. C., the temperature
depending on the desired shrink. Subsequently, the film is wound up
in a customary manner.
[0214] Following the optional annealing or heat-setting step the
film is transferred to a cooling zone where generally air, either
cooled or kept at the ambient temperature, is employed to cool down
the film. The temperature of said cooling zone is therefore
typically comprised between about 20.degree. C. and about
40.degree. C. At the end of the line, the edges of the film,
grasped by the clips and not oriented, are trimmed off and the
obtained bi-axially oriented, heat-shrinkable or heat-set film is
then wound up, with or without prior slitting of the film web to
the suitable width.
[0215] A second embodiment of the presently disclosed subject
matter is a method for manufacturing the multi-compartment package
of the presently disclosed subject matter, such a method comprising
the steps of: [0216] i) providing two outermost and at least one
internal, optionally pre-cut, crystallizable films; [0217] ii)
providing at least two products to be packaged; [0218] iii)
stacking an outermost film, the product(s), the internal
film(s)--alternating the products and the internal film(s)--and the
other outermost film, up to the desired number of compartments is
obtained; [0219] iv) sealing and simultaneously crystallizing the
stack of films along a peripheral circumferential continuous
sealing area thus providing a peripheral circumferential continuous
rigid frame, and [0220] v) optionally, simultaneously or
afterwards, cutting the stack of films all around all around
outside the frame thus providing the multi-compartment package; or,
alternatively the steps of: [0221] a) providing two outermost and
at least one internal, optionally pre-cut, crystallizable films;
[0222] b) providing at least two products to be packaged; [0223] c)
placing in stack an outermost film, a product and an internal film;
[0224] d) sealing and simultaneously crystallizing the stack of
films along a peripheral circumferential continuous sealing area
thus providing a peripheral circumferential continuous rigid frame;
[0225] e) optionally, simultaneously or afterwards, cutting the
stack of films all around outside the frame thus providing the
first compartment of the package; [0226] f) placing a stack of "a
product/a film" or of "a film/a product/a film", onto the
compartment formed in steps c) to e); [0227] g) repeating point d)
to f) for each new compartment up to the desired number of
compartments is obtained, thus providing the multi-compartment
package or, alternatively the steps of: [0228] A) providing two
outermost and at least two internal, optionally pre-cut,
crystallizable films; [0229] B) providing at least two products to
be packaged; [0230] C) placing in stack a film, a product and a
film; [0231] D) sealing and simultaneously crystallizing the stack
of films along a peripheral circumferential continuous sealing area
thus providing a peripheral circumferential continuous rigid frame;
[0232] E) optionally, simultaneously or afterwards, cutting the
stack of films all around outside the frame thus providing the
first compartment of the package; [0233] F) manufacturing at least
another compartment following steps A to E; [0234] G) stacking the
first and the new compartment(s), optionally placing a product in
between; [0235] H) sealing or gluing together the first and the
other new compartment(s), simultaneously or one after the other if
more than two, up to the desired number of compartments is
obtained, thus providing the multi-compartment package.
[0236] Independently of the method used, a partial crystallization
of the films along the sealing area occurs during the sealing
operation thus providing the rigid frame.
[0237] FIGS. 7A and 7B illustrate methods for manufacturing
embodiment 1A and, respectively, embodiment 1B of a three
compartment package according to the presently disclosed subject
matter. In this scheme for the sake of clarity, only steps iii)
(stacking) and iv) (sealing) of the present manufacturing process
are represented, being the other steps of i) providing the films,
optionally pre-cut, ii) providing the products and, v) optionally
cutting the stack of films to provide the final package are also
meant to be included.
[0238] The first embodiment of manufacturing the present package
disclosed above may be advantageously used.
[0239] According to this first embodiment, the outermost films, the
internal film(s) and the products are alternated and stacked up to
the desired number of compartments is obtained, then all the films
in stack are sealed and cut. The films may also be pre-cut before
the stacking step; in this case the further cutting step can be
optional. During the sealing step, the films are heat crystallized
thus forming the rigid frame of the package.
[0240] In embodiment 1A of the present package only one internal
film is present. Accordingly, in the manufacturing process of this
package, the sequence of films and products to be stacked is:
"film/(product/film): where "n" is an integer number higher than 1
representing the number of compartments desired.
[0241] In a two-compartments package according to embodiment 1A
(n=2) the sequence of films and products in stack is:
"film/product/film/product/film", wherein the products and the
films can be the same or different.
[0242] In a more than two-compartments package (n>2) according
to embodiment 1A, the sequence of films and products in stack is:
"film/(product/film) n>2", wherein the products and the films
can be the same or different.
[0243] In embodiment 1A of the present package two adjacent
compartments share the same internal film and the compartments are
opened preferably one after the other in the same order they have
in the package.
[0244] In another embodiment (1B), each compartment has its own
internal films, namely there are two internal films between each
couple of adjacent products in stack.
[0245] In the manufacturing process of the package according to
embodiment 1B, the sequence of films and products to be stacked
is:
"(film/product/film).sub.n" where "n" is an integer number higher
than 1 representing the number of compartments desired.
[0246] In a two-compartment package according to embodiment 1B
(n=2) the sequence of films and products in stack is:
"film/product/film/film/product/film", wherein the products and the
films can be the same or different.
[0247] In case of n compartments, where n is higher than 2, the
sequence of films and products in stack is:
"(film/product/film)n>2"
[0248] In embodiment 1B two adjacent products will be separated by
two internal films. This embodiment 1B allows the consumer to
detach sealed compartments, while keeping each portion still
packaged, and to open them later and independently.
[0249] To facilitate the detachment of each single sealed
compartment from the others, the bonding between adjacent
compartments may be suitably weakened, for instance by imparting
higher peel properties to the surfaces of the films directly
involved in said bonding.
[0250] In an advantageous embodiment 1B, the bonding between the
films of adjacent compartments (inter-compartments bonding) will be
weaker than the bonding within the films of each compartment
(intra-compartment bonding) thus allowing a clean detachment of
each sealed compartment and avoiding untimely opening of the same.
A different bonding may also be obtained for instance by selecting
different means for intra- and inter-compartments bonding, such as
sealing vs gluing etc.
[0251] In such a case, the manufacturing process may be according
to a third embodiment of said process. If the strength of the
bonding imparted by gluing is lower than those conferred by
sealing, the detachment of each still sealed compartment will be
facilitated.
[0252] According to a second variant of a manufacturing process of
the present multi-compartment package, represented in FIGS. 8A and
8B, a first compartment is made by stacking in sequence a film, a
product and a film and by sealing the stacked films; afterwards, a
new stack of a product and one/two film(s)--arranged as
"product/film" for manufacturing the package of embodiment 1A or as
"film/product/film" for embodiment 1B--is added onto the first
compartment previously manufactured and the thus formed stack of
films and products are sent again to the sealing station, were the
films are sealed, crystallized and cut if needed.
[0253] Each new product to be packaged is added--covered by one or
sandwiched between two film(s)--to the package already made in the
previous steps, up to the desired number of compartments is
obtained. This stepwise process has the advantage of repeating the
sealing/crystallizing step several times thus providing the
multi-compartment package with a more rigid frame. A higher
rigidity may be advantageous in case of heavier or more delicate
products. This process may also be useful when there is the need to
alternate different products.
[0254] However, in case of a package with a higher number of
compartments (i.e. more than 3) it may be advantageous to replace
one or more of the sealing steps d) of the present second method
with one or more gluing steps as the rigidity conferred by the
sealing steps already performed may suffice for the final use of
the package. Gluing steps may be carried out, for instance, as
described below for the third manufacturing method.
[0255] FIGS. 8A and 8B illustrate a second method for manufacturing
embodiment 1A and, respectively, embodiment 1B of a three
compartment package.
[0256] In this scheme for the sake of clarity, only steps c and f)
(stacking), d) (sealing) and g) (their repetition) of the present
manufacturing process are represented, being the other steps of a)
providing the films, optionally pre-cut, b) providing the products
and, e) optionally cutting the stack of films to provide the final
package are also meant to be included.
[0257] For the method of this second embodiment, the sequence of
components in the final package is "film/(product/film).sub.n" for
embodiment 1A or "(film/product/film).sub.n" for embodiment 1B
being n the total number of compartments (n>1).
[0258] In a third variant of the of the present manufacturing
method, two or more pre-made compartments, are joined together by
sealing or, in alternative, by gluing.
[0259] FIGS. 9A and 9B illustrate this third method for
manufacturing embodiment 1A and, respectively, embodiment 1B of a
three compartment package according to the presently disclosed
subject matter.
[0260] In this scheme for the sake of clarity, only steps C)
(stacking a film, a product and a film), D) (sealing), G) (stacking
each new compartment onto the previous one(s), optionally placing a
product in between) and H) (sealing or gluing) of the present
manufacturing process are represented, being the other steps of A)
(providing the films, optionally pre-cut), B) (providing the
products), E) (optionally cutting the stack of films), F)
(manufacturing at least another compartment), to provide the final
package are also meant to be included.
[0261] In the present method, the pre-made compartments may be
sealed or glued simultaneously in stack or added and sealed /glued
stepwise, one after the other.
[0262] If the pre-made compartments are stacked or added without
any further product interposition, a multi-compartment package
according to embodiment 1B will be obtained.
[0263] In alternative, if a product is inserted between each couple
of adjacent compartments, a multi-compartment package according to
embodiment 1A may be manufactured. In this case, especially for
food products, the compartments are advantageously joined together
by sealing rather than by gluing to prevent undesired product
contaminations.
[0264] As used herein the term "gluing" refers to placing a
discrete or continuous layer of an adhesive, preferably along the
frame, onto at least one of the facing surfaces of two adjacent
compartments to be glued and joining the compartments by applying a
pressure sufficient to let them adhere to each other.
[0265] The term "adhesive" is used herein to indicate any material
that enables the adhesion of two compartments to each other.
[0266] The thickness of the layer of adhesive can be comprised
between 0.2 and 10 .mu.m, for example from 0.5 to 5 .mu.m, or from
1 to 3 .mu.m.
[0267] The adhesives suitable for joining the compartments
according to this embodiment are well known in the art. For
instance suitable adhesives may be the aqueous dispersions sold by
Paramelt under the trade name of Aquaseal or the compositions
described in WO 2005/021638 (e.g., U.S. Pat. Nos. 7,803,865;
8,193,275; and 8,232,336) or in WO 2009/055275 (e.g., U.S. Pat. No.
8,475,878) under the code DPOD 8501. Each of these patents is
incorporated herein in its entirety by reference.
[0268] The so called "cold seal" materials may be used, as those
supplied for example by Fabrico (division of EIS), Basic Adhesive,
Printpack Inc.
[0269] Adhesive materials known as "hot melt pressure sensitive
adhesives (HMPSA)," are also suitable for the disclosed subject
matter, for example those commercialized by Bostik and Henkel
[0270] Systems for applying hot melt adhesives are e.g. hot melt
handguns, roll coaters, benchtop extruders, automatic extrusion,
fiberization system.
[0271] Various adhesive coatings are described, for example, in WO
2005/021638 and WO 2011/083342.
[0272] The adhesive layer has to be deposited onto the external
surfaces of the compartments to be joined, for example, along the
frame.
[0273] In case of cold seal, this can be done on both the surfaces
to be joined.
[0274] The layer of adhesive can be discrete or continuous along
the frame.
[0275] The adhesive may be applied along the frame as described,
for instance, in WO 2011/083342.
[0276] In a variant of this third embodiment for manufacturing
multi-compartments packages according to embodiment 1B, the
pre-made compartments may be joined by gluing. Advantageously it is
possible to select gluing conditions and adhesives in such a way to
obtain inter-compartments bonding weaker than the intra-compartment
bonding, thus facilitating the removal of each still sealed
compartment.
[0277] The methods of manufacturing the present package described
above may be implemented with suitable packaging machines such as
tray lidding and thermoforming machines with contour sealing and
cutting.
[0278] Specific example of suitable machines that can be adapted to
run the process of the present disclosed subject matter include for
instance Multivac 400 and Multivac T550 by Multivac Sep. GmbH,
Mondini E380, E390 or E590 or Trave by Mondini S.pA, Ross A20 or
Ross 545 by Ross-Reiser, Meca-2002 or Meca-2003 by Mecaplastic, the
tray lidding machines manufactured by Sealpac, Ulma Taurus and Ulma
Scorpius supplied by Ulma Packaging, Ishida QX and the like
machines.
[0279] Thermoforming machines are suitable for the process
described above, without significant modifications. Especially in
case of food products to be packaged, a slicer can be
advantageously added in order to slice the product.
[0280] In one embodiment, an additional conveyor carrying the
weighted product(s) to the stacking zone can also be advantageously
provided. Afterwards, the product(s) can be positioned onto the
belt carrying the films and the stacking of films and products is
repeated up to the desired number of compartments is achieved.
Then, the stacked films and products are carried to the
thermoforming zone, where sealing, crystallization and cutting
occur.
[0281] In another embodiment, a pre-cutting unit to pre-cut the
film is advantageously provided in order to cut the films from the
roll at a measure suitable for the package. Some existing tray
lidding packaging lines supplied e.g by Risco and Vemag are already
equipped with pre-cutting unit, for instance those for the
packaging of minced meat.
[0282] In another embodiment, the cutting of the package is
performed after the sealing step. In another embodiment, the
cutting of the package is performed at the same time of the sealing
step.
[0283] In case a tab for easy opening is desired, the cutting blade
will be shaped in such a way to provide the tab when cutting the
films, as known to the person skilled in the art.
[0284] In case the films are of different composition or the
outermost films are printed, the packaging machine may provide the
housing for more than one roll of films.
[0285] Sealing may be carried out by means of a heated frame by
setting the machine at temperatures, in case of polyester based
films, of from 140 to 220.degree. C., for example, from 170 to
200.degree. C. and at a pressure of from 2 to 8 bar, for example,
from 4 to 7 bar. Sealing times are typically in the order of 0.01
to 2.0 seconds, for example, from 0.5 to 1.0 seconds.
[0286] However, other known sealing techniques such as ultrasonic
welding may also be used, providing that they are able to induce an
at least partial crystallization of the films along the sealing
area.
[0287] In case of HDPE or polypropylene based films, lower sealing
temperatures are generally selected, for instance in the range of
from 120 to 180.degree. C. providing that the selected temperatures
are suitable for at least partially crystallizing the polymers
under the operational sealing conditions.
[0288] The sealing bar can have different shapes such as to obtain,
for example, a flat or a thermoformed area where the films are
sealed to each other, the thermoformed option being preferred, as
it provides for a higher rigidity of the frame. Such sealing bars
are commercialized by packaging machine suppliers.
[0289] FIGS. 6A-E illustrate cross-sections of some suitable
sealing bars. In particular the sealing bar profile can be flat or
rounded. The sealing bar may have a thermoforming profile, as shown
in FIGS. 6A or 6E, namely the bar will seal the films along the
sealing area while imparting a desired shape to the at least
partially crystallized frame, further increasing its rigidity. For
instance, according to the profile of the sealing bars illustrated
in FIG. 6A or 6E, there will be areas where, upon sealing, a higher
pressure will be applied onto the stacked films and,
correspondingly, a higher degree of crystallization will be
imparted to the frame.
[0290] Typically, the width of the sealing area of the package,
i.e. the width of the frame, is from 1 mm to 20 mm, for example,
from 2 mm to 15 mm, or from 3 to 10 mm.
[0291] The dimensions, in terms of area extension, of the packaged
product are not limited, provided that they do not exceed the
dimensions of the cut films, and allow a suitable frame to be
formed.
[0292] The film dimensions can be adjusted according to the product
dimensions and to the needed width of the frame. The width of the
frame has to be sufficient to confer the suitable stiffness to the
package, depending inter alia on the total weight of the packaged
products and on the package dimensions.
[0293] The multi-compartment package object of the presently
disclosed subject matter may be particularly useful for the storage
of products which are thin and flexible such as sliced food
products or medical product like surgery gloves, sterilized wipes,
beauty wipes, patches, gauzes, strips or soaked plasters or
bands.
[0294] The package of the presently disclosed subject matter may be
used to store sliced food products such as cheese and processed
meat. Other possible thin or sliced foods comprise fish and meat
carpaccio, smoked fishes, piadina, crepes disks ready to be filled,
sweet and salt dough ready to be cut and/or cooked in the oven or
fried or filled with a stuffing and then cooked. It is also
possible to insert different food products in the same package in
order to allow the consumer to have in a single package a specific
combination of food products.
[0295] For the purpose of the present description and of the claims
which follow, except where otherwise indicated, all numbers
expressing amounts, quantities, percentages, and so forth, are to
be understood as being modified in all instances by the term
"about". Also, all ranges include any combination of the maximum
and minimum points disclosed and include any intermediate ranges
therein, which may or may not be specifically enumerated
herein.
EXAMPLES
[0296] A three-layer film having the composition reported in Table
1 and a total thickness of 33 .mu.m was coextruded through a
3-layer feedblock.
TABLE-US-00001 TABLE 1 Layer, thick- % ww ness Trade Name,
Supplier, in the (.mu.m) Chemical Nature layer Properties layer 1,
EASTAR PETG 6763, 60% Density 1.27 g/cm.sup.3; 2.5 .mu.m Eastman
Chemical, Glass Transition 81.degree. C. Polyethylene Melt Flow
Rate (Cond. Terephthalate/Glycol 200.degree. C./05.00 kg (G)) 2.8
g/10 min Viscosity Solution (Brook- field method) 0.75 mPa sec
PRIMACOR 3440, 15% Comonomer content 9.7% DOW, Ethylene/Acrylic
Density 0.938 g/cm.sup.3 Acid Copolymer Melt Flow Rate (Cond.
190.degree. C./02.16 kg (G)) 10 g/10 min Vicat softening point
76.degree. C. EASTAPAK 25% Density 1.4 g/cm.sup.3 COPOLYESTER 9921,
Melting Point (Tm) Eastman Chemical, 255.degree. C. Polyethylene
Terephthalate layer 2, EASTAPAK 60% Density 1.4 g/cm.sup.3 24 .mu.m
COPOLYESTER 9921, Melting Point (Tm) Eastman Chemical, 255.degree.
C. Polyethylene Terephthalate EASTAR PETG 6763, 40% Density 1.27
g/cm.sup.3 Eastman Chemical, Glass Transition 81.degree. C.
Polyethylene Melt Flow Rate (Cond. Terephthalate/Glycol 200.degree.
C./05.00 kg (G)) 2.8 g/10 min Viscosity Solution (Brook- field
method) 0.75 mPa sec layer 3, EASTAPAK 98% Density 1.4 g/cm.sup.3
6.5 .mu.m COPOLYESTER 9921, Melting Point (Tm) 255.degree. C.
Eastman Chemical, Polyethylene Terephthalate SUKANO G dc S503, 2%
Vicat softening point Sukano AntiBlock and 82.degree. C. Slip in
Polyethylene Terephthalate/Glycol
[0297] The three layers were then distributed through a flat die,
having a multi-manifold system. The melt out of the die was
quenched onto a chill rolls; electrostatic pinning was applied to
increase the contact between melt and chill roll kept at 19.degree.
C.
[0298] The so formed cast film was then biaxially oriented. The
stretching was done simultaneously on a tenterframe, at ratios of
3.8:1 in both MD and TD directions, and at temperatures of
98.degree. C. in the preheating zones and 96.degree. C. in the
stretching zones. Before oven exit, the film was annealed at a
temperature of 200.degree. C.
[0299] The film properties are reported in Table 2 and 3, as well
as the reference ASTM for the test method adopted for the
measurements.
TABLE-US-00002 TABLE 2 Free Shrink ASTM D2732 temperature LD TD
120.degree. C. 0 0 140.degree. C. 2 0 160.degree. C. 5 2
TABLE-US-00003 TABLE 3 longitudinal transversal Mechanical Property
direction direction at 23.degree. C. (LD) (TD) ASTM elastic modulus
(Kg/cm.sup.2) 36000 36000 D882 tensile at break (Kg/cm.sup.2) 2250
2200 D882 elongation at break (%) 150 150 D882
[0300] A machine Mondini Tray Lid E380 was used to manufacture 30
packages according to the presently disclosed subject matter;
Sealing conditions applied were: 190.degree. C., 1 sec, 5 bar.
[0301] Each package (according to embodiment 1A) contained 4
compartments for a total of 5 films; one slice of cooked ham was
packaged in each compartment and each slice of cooked ham was about
1 mm thick. Five films were superimposed in stack, alternating them
with the products, to obtain four compartments.
[0302] The shape of the packages so obtained is shown in FIG. 1 and
each package was provided with a tab (4). The main dimensions of
the rectangular package were 160 mm (width).times.205 mm (length),
the sealing width was 5 mm and the distance between the two closest
opposite seals was 135 mm.
[0303] The packages were judged acceptable in terms of rigidity of
the frame by three panelists: in fact only a slight bending of the
packages due to the weight of the products was observed. In
addition, the packages were manually opened and the opening was
really smooth due to the peelability of the films.
[0304] In conclusion, the multi-compartment flexible package of the
presently disclosed subject matter does not require a supplemental
tray. In fact the package is sufficiently rigid as such, thanks to
the partial heat-induced crystallization of the crystallizable
polymer in correspondence of the sealing area. An embodiment of the
present package in use is not, or is only slightly, bent and
remained substantially flat during its handling. The absence of an
additional tray allows a significant reduction of plastic material
as well as of manufacturing and disposal costs.
[0305] The partially crystallized area--which appears as a
peripheral circumferential continuous rigid frame--is obtainable
during conventional sealing of the package and advantageously does
not require additional sealing or forming operations or
equipment.
[0306] Notwithstanding the much lower content of plastics, the
multi-compartment package embodiments of the presently disclosed
subject matter may provide for at least the same advantages of
conventional multi-compartment packages, for instance: [0307]
preservation of single portions of different or same product(s),
allowing their individual use; [0308] improved conservation and
durability of the packaged products, including air sensitive foods
such as sliced food products or medical products, under modified
atmosphere or vacuum; [0309] no contaminations (bacteria, odor,
taste); [0310] prevention of sticking and breaking of sliced food,
such as cheese or processed meat, that occur when a high number of
slices of these products are stuffed in the same compartment of
conventional packages and are therefrom removed; and [0311] easy
opening the compartment(s) which contains each single portion.
[0312] Embodiments of the present package may be considered as a
"green" product that not only requires a significantly lower amount
of plastics but can be easily recycled, when made of a single
plastic material, or it may also be bio-degradable if composed of
biodegradable polyesters, i.e. a multi-compartment package more
eco-friend with respect to conventional multi-compartments packages
currently on the market.
* * * * *
References