U.S. patent application number 13/704159 was filed with the patent office on 2013-05-09 for hydrogen generating, oxygen scavenging closure cap.
This patent application is currently assigned to La Seda De Barcelona S.A.. The applicant listed for this patent is Hilde Krikor, Luc Verheyen. Invention is credited to Hilde Krikor, Luc Verheyen.
Application Number | 20130112688 13/704159 |
Document ID | / |
Family ID | 42558166 |
Filed Date | 2013-05-09 |
United States Patent
Application |
20130112688 |
Kind Code |
A1 |
Krikor; Hilde ; et
al. |
May 9, 2013 |
HYDROGEN GENERATING, OXYGEN SCAVENGING CLOSURE CAP
Abstract
The closure cap (1) is capable of generating molecular hydrogen
from a chemical reaction with water, and can be used for closing a
container and for scavenging oxygen. The cap (1) comprises a shell
(10), an active layer (11) that is capable of chemically reacting
with water and generating molecular hydrogen, and a liner (12) that
is permeable to water vapour and to molecular hydrogen; said active
layer (11) has an inner face (11a), an outer face (11b) and a
circumferential edge (11c); the shell (10) comprises an housing and
the active layer (11) is entirely contained in said housing; the
outer face (11b) and the circumferential edge (11c) of the active
layer (11) are in contact with the shell (10) and are bonded to the
shell (10); the liner (12) is closing said housing (H) and is
bonded to the shell (10) on the whole periphery of the active layer
(11) and to the inner face (11a) of the active layer (11).
Inventors: |
Krikor; Hilde; (Deurne,
BE) ; Verheyen; Luc; (Brecht, BE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Krikor; Hilde
Verheyen; Luc |
Deurne
Brecht |
|
BE
BE |
|
|
Assignee: |
La Seda De Barcelona S.A.
Barcelona
ES
|
Family ID: |
42558166 |
Appl. No.: |
13/704159 |
Filed: |
June 14, 2011 |
PCT Filed: |
June 14, 2011 |
PCT NO: |
PCT/EP2011/059819 |
371 Date: |
December 13, 2012 |
Current U.S.
Class: |
220/212 |
Current CPC
Class: |
A23L 2/42 20130101; C01B
5/00 20130101; B65D 2565/385 20130101; Y02E 60/36 20130101; A23L
3/3436 20130101; B65D 51/24 20130101; B65D 51/244 20130101; B65D
81/24 20130101; Y02E 60/362 20130101; C01B 3/065 20130101; C01B
3/08 20130101 |
Class at
Publication: |
220/212 |
International
Class: |
B65D 51/24 20060101
B65D051/24 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 18, 2010 |
EP |
10166500.8 |
Claims
1. A closure cap (1) comprising a shell (10) that can be fitted
onto a container for closing an opening of said container, an
active layer (11) that is capable of chemically reacting with water
and generating molecular hydrogen, and a liner (12) that is
permeable to water vapour and to molecular hydrogen, wherein said
active layer (11) has an inner face (11a), an outer face (11b) and
a circumferential edge (11c), wherein the shell (10) comprises an
housing (H) and the active layer (11) is entirely contained in said
housing (H), wherein the outer face (11b) and the circumferential
edge (11c) of the active layer (11) are in contact with the shell
(10) and are bonded to the shell (10), and wherein the liner (12)
is closing said housing (H) and is bonded to the shell (10) on the
whole periphery of the active layer (11) and to the inner face
(11a) of the active layer (11).
2. The closure of claim 1, wherein the shell (10) comprises a top
wall (100) having a recess (103) that forms the said housing (H),
and wherein the liner (12) is closing the said recess (103) and is
bonded to the shell (10) on the whole periphery of the said recess
(103).
3. The closure of claim 1, wherein the shell (10) comprises a
shoulder portion (104) that surrounds the recess (103), and the
liner (12) is bonded to the shoulder portion (104) on the whole
periphery of the recess (103).
4. The closure of claim 3, wherein the active layer (11) is flush
with said shoulder portion (104).
5. The closure of claim 2, wherein the active layer (11) completely
fills the recess (103) without protruding outside the recess
(103).
6. The closure of claim 1, wherein the shell (10) comprises an
inner cylindrical sealing lip (102a) and wherein the liner (12) is
not in contact with the inner cylindrical sealing lip (102a).
7. The closure of claim 1, wherein the active layer (11) and the
liner (12) are over injected onto a moulded shell (10).
8. The closure of claim 1, wherein the active layer (11) comprises
an active substance that is capable of chemically reacting with
water and generating molecular hydrogen.
9. The closure of claim 8, wherein the active substance is selected
from the group comprising Group I, II, and III metals, Group I, II,
and III metal hydrides, rare earth metals, rare earth hydrides,
alkali metal borohydrides, alkaline earth metal borohydrides,
alkali metal aluminum hydrides, silicon hydrides, tin hydrides, and
combinations thereof.
10. The closure of claim 8, wherein the active substance is
selected from the group comprising sodium hydride, lithium hydride,
sodium borohydride, sodium metal, lithium metal, potassium metal,
calcium hydride, magnesium hydride, lithium aluminum hydride, and
combinations thereof.
11. The closure of claim 1, wherein the active layer (11) comprises
a polymeric matrix.
12. The closure of claim 11, wherein the polymeric matrix comprises
a polyethylene.
13. The closure of claim 11, wherein the polymeric matrix comprises
an ethylene vinyl acetate copolymer.
14. The closure of claim 11, wherein the polymeric matrix comprises
a thermoplastic elastomer.
15. The closure of claim 14, wherein the thermoplastic elastomer
comprises a polyolefin blend.
16. The closure of claim 14, wherein the thermoplastic elastomer
comprises SEBS.
17. The closure of claim 1, wherein the hardness of the active
layer (11) is not less than Shore A hardness 40.
18. The closure of claim 1, wherein the liner (12) comprises a
polyethylene.
19. The closure of claim 1, wherein the liner (12) comprises a
thermoplastic elastomer.
20. The closure of claim 19, wherein the thermoplastic elastomer
comprises a polyolefin blend.
21. The closure of claim 19, wherein the thermoplastic elastomer
comprises SEBS.
22. The closure of claim 1, wherein the liner (12) comprises an
ethylene vinyl acetate copolymer.
23. The closure of claim 1, wherein the shell (10) is made of a
polymeric material comprising a polyolefin.
24. The closure of claim 1, wherein the material of the liner (12)
and the material of the closure shell (10) comprise, or are made
of, at least one identical polymer.
25. The closure of claim 1, wherein the liner (12) is only thermal
bonded to the closure shell (10) and to the active layer (11).
26. The closure of claim 1, wherein the shell (10), the active
layer (11), and the liner (12) have respectively three different
colours in order to visually differentiate them.
27. The closure of claim 1, having a density less than 1.
28. An assembly comprising a plastic container and a closure cap,
wherein the closure cap (1) is defined by claim 1.
29. The assembly of claim 28, wherein the plastic container and/or
the closure cap (1) comprises a catalyst for promoting a reaction
between molecular hydrogen and molecular oxygen.
Description
TECHNICAL FIELD
[0001] The invention relates to a novel closure cap that is capable
of generating molecular hydrogen from a chemical reaction with
water, and that can be used for closing a container and for
scavenging oxygen. The container can be used for storing any
oxygen-sensitive substance that can be altered by oxygen, and in
particular a food substance or a beverage such as for example
juice, beer, wine, . . .
PRIOR ART
[0002] Aromatic polyester resins, and in particular polyethylene
terephthalate (PET), are widely used in the packaging industry for
making various types containers for storing any substance, and in
particular for storing food substance or a beverage.
[0003] PET has a number of valuable properties for packaging, but
lacks sufficient gas barrier properties for many applications. In
particular because of its oxygen permeability, PET alone is not
appropriate for packaging oxygen-sensitive food and beverage
products such as beer, fruit juices, some carbonated soft drinks,
etc. . . . PET is also permeable to carbon dioxide, which in turn
leads to a short shelf life for carbonated products, such as
carbonated soft drinks, stored in PET containers.
[0004] In order to improve the gas barrier properties of packaging
articles, in particular oxygen and/or carbon dioxide barrier
properties, it is now common to use multilayered packaging
articles, and in particular multilayered containers, that include
at least one barrier layer. For example, in the field of bottle
packaging, a typical and common multilayered wall structure for a
hollow rigid container is a three-layer wall: two internal and
external layers made of PET, and one intermediate gas barrier layer
sandwiched between the two PET layers.
[0005] A first known type of barrier layer is made of, or
comprises, polymers that have excellent gas-barrier properties, in
particular to O.sub.2 and/or CO.sub.2, and is generally referred as
"passive barrier layer". Among the polymers used for making passive
barrier layers, homo- or copolymers of polyamides are commonly
used. Among these polyamides, the so-called "MXD6" or "MXD6 nylon"
(specific polyamide material manufactured by Mitsubishi Gas
Chemical Company, Japan) is preferably used, i.e. a
poly(m-xylyleneadipamide) produced by the polycondensation of a
diamine component composed mainly of m-xylylenediamine and a
dicarboxylic acid component composed mainly of adipic acid.
[0006] A second known type of barrier layer, which has been more
recently developed, is made of, or comprises, polymeric composition
that has oxygen-scavenging properties, and is generally referred as
"active barrier layer". Generally speaking, an active barrier layer
reacts with the oxygen and "captures" the oxygen when the oxygen
penetrates into the layer. Such active barrier layer is thus
progressively "consumed" in use.
[0007] Examples of polymeric compositions used for making active
barrier layer are described notably in European patent application
EP-A-0 301 719 or in European patent application EP-A-0 507 207.
Said polymeric compositions generally comprise an oxidizable
polymer and a transition metal catalyst. In EP-A-0 301 719, the
preferred oxidizable polymers are polyamides, and especially MXD6.
In EP-0 507 207, one preferred oxidizable polymer is polybutadiene.
In both cases, preferred transition metal catalysts are transition
metal salts, an in particular cobalt stearate. Other known metal
salts used for making such composition are rhodium, manganese,
copper, iron.
[0008] With multilayered packaging articles having at least one gas
barrier layer comprising a polyamide (e.g. MXD6) and a polyester
(e.g. PET), very good results can be achieved in terms of shelf
life of the packaged products. More especially when the barrier
layer comprises a polyamide (e.g. MXD6), polyester (e.g. PET), and
a catalyst such as a cobalt salt, the multilayered packaging
article can be used for storing oxygen-sensitive products, such as
beer, fruit juice, or the like. The shelf life of the packaged
product widely depends of the amount of polyamide in the packaging
article and of the thickness of the barrier layer.
[0009] In return, the use of gas barrier polymer, like polyamide in
the container wall renders the recycling of the container more
difficult. In addition, when polyamide is used, in particular for
making a monolayer container, there is a risk of formation of haze
in the container wall due to the orientation of the polyamide
during the process for making the container. Said haze formation in
the container wall is obviously detrimental for all the
applications where it is important to have a transparent container,
--i.e. a container whose wall has no eye-visible whitening or haze,
in order to have a better appearance of the packaged product.
[0010] In order to improve the O.sub.2 scavenging performance of a
plastic container, it is also known to close the container with a
closure cap comprising a layer having O.sub.2 scavenging
properties.
[0011] Another recent route for making a container having oxygen
scavenging properties is described in PCT application WO
2008/090354. The O.sub.2 scavenging properties are obtained by
using an active substance, such as for example a hydride, that is
capable of chemically reacting with water and generating molecular
hydrogen, and by making said molecular hydrogen react with oxygen
which may ingress the container. In the variant of FIG. 4 of s PCT
application WO 2008/090354, said active substance is incorporated
in a plug that is positioned in a cap. In such a variant, the
active substance can however prejudicially contaminate the product
stored in the container.
OBJECTIVE OF THE INVENTION
[0012] A general and main objective of the invention is to propose
a novel closure cap that includes an active substance capable of
chemically reacting with water and generating molecular hydrogen
into a container.
[0013] A more particular objective of the invention is to propose a
novel closure cap, that includes an active substance capable of
chemically reacting with water and generating molecular hydrogen
into a container, and that can be in contact with the content of
the container without any risk of contamination of the said
substance by the active substance.
[0014] A more particular objective of the invention is to propose a
novel closure cap, that includes an active substance capable of
chemically reacting with water and generating molecular hydrogen
into a container, and that can be easily manufactured.
[0015] A more particular objective of the invention is to propose a
novel active closure cap for a container, said cap being suitable
for scavenging oxygen that may penetrate inside the container,
notably through the permeable wall of the container, or oxygen that
is present in the head space of the container.
SUMMARY OF THE INVENTION
[0016] These objectives are achieved by the closure cap of claim 1.
This closure cap of the invention comprises a shell that can be
fitted onto a container for closing an opening of said container,
an active layer that is capable of chemically reacting with water
and generating molecular hydrogen, and a liner that is permeable to
water vapour and to molecular hydrogen; said active layer has an
inner face, an outer face and a circumferential edge; the shell
comprises an housing and the active layer is entirely contained in
said housing; the outer face and the circumferential edge of the
active layer are in contact with the shell and are bonded to the
shell; the liner is closing said housing and is bonded to the shell
on the whole periphery of the active layer and to the inner face of
the active layer.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Other characteristics and advantages of the invention will
appear more clearly on reading the following description of several
closure cap embodiments, which description is given by way of
non-limiting example and with reference to the accompanying
drawings, in which:
[0018] FIG. 1 is a view in cross-section of a first variant of
closure cap fitted onto a container neck,
[0019] FIGS. 2 to 6 are partial views in cross-section of five
other variants of closure cap.
DETAILED DESCRIPTION
[0020] In reference to FIG. 1, a closure cap 1 of the invention is
fitted onto a standard neck 2 of a plastic container C comprising a
top opening (container mouth), like for example a bottle neck. This
top opening of the neck 2 is knowingly used for filling the
container with a product and/or for pouring the product outside the
container. In this particular embodiment, the closure cap 1 is
screwed on the container neck 2. In another variant, the closure
cap 1 could be snapped on the container neck 2.
[0021] The material and the shape of the container are not
important. In particular the container can be for example any
plastic container or any cardboard container; the container can be
for example a bottle-shaped container, a flask, a jar, a tube, a
bag, a pouch. Within the scope of the invention, the container can
be rigid, semi rigid or flexible. The containers contemplated in
the present invention may be either of a monolayer or a multilayer
construction. Suitable materials which may be used as a layer or
part of one or more layers in either monolayer or multilayer
containers include polyester (including but not limited to PET),
polyetheresters, polyesteramides, polyurethanes, polyimides,
polyureas, polyamideimides, polyamides, polyphenyleneoxide, phenoxy
resins, epoxy resins, polyolefins (including but not limited to
polypropylene and polyethylene), polyacrylates, polystyrene,
polyvinyls (including but not limited to polyvinyl chloride)) and
combinations thereof. All of the aforementioned polymers may be in
any desired combination thereof.
[0022] The container C can be manufactured by using any method
known in the art, including but not limited to injection moulding,
injection blow moulding (IBM), injection stretch-blow moulding
(ISBM), extrusion blow moulding, thermoforming, rotational
moulding, folding.
[0023] This closure cap 1 comprises three main components: a
closure shell 10, an active layer 11, and a liner 12.
Closure Shell 10
[0024] The closure shell 10 is a plastic piece that comprises a top
wall 100 and a lateral wall 101. The top wall 100 forms a disc and
comprises an outer face 100a and an inner face 100b that is
intended in use to be oriented toward the inside (IN) of the
container (FIG. 1). The lateral wall 101 is substantially
perpendicular to the top wall and forms a substantially cylindrical
lateral skirt 101. The inner face 101a of this skirt 101 comprises
a screwing thread 101b that can cooperate with the screwing thread
20 of the neck 2 for securing the closure cap 1 onto the neck
2.
[0025] The closure shell 10 also comprises sealing means for
substantially hermetically closing the top opening of the container
neck 2, and avoiding any leakage of the product contained in the
container. In this particular example, these sealing means comprise
an inner cylindrical sealing lip 102a and an outer cylindrical
sealing lip 102b, that extend both from the inner face 100b of the
top wall 100. The outer sealing lip 102b is positioned between the
inner sealing lip 102a and the skirt 101. These sealing lips 102a
and 102b can be replaced by any sealing element that cooperates
with the container neck for sealing the top opening of the neck 2,
once the closure cap 1 is fitted onto the neck 2.
[0026] The inner face 100b of the top wall 100 comprises a central
recess 103 that is made in the thickness of the top wall. This
recess 103 is delimited by a bottom wall 103a and a peripheral
lateral wall 103b. The lateral wall 103b extends downwardly from
the bottom wall 103a and surrounds the bottom wall 103a. This
recess 103 forms a housing H for the active layer 11.
[0027] The closure shell 10 further comprises a shoulder portion
104 that surrounds the recess 103. Said shoulder portion 104 joins
the lateral wall 103b of the recess 103 to the internal sealing lip
102a.
[0028] The material of the closure shell 10 can be any known
thermoplastic material that can be moulded in a mould, and more
particularly any known thermoplastic material that can be processed
by injection moulding. Preferably, the closure shell is made from a
polyolefin, like for example polypropylene, polyethylene,
polyethylene terephthalate or a blend thereof. A good candidate for
making the closure shell 10 is HDPE (High Density
Polyethylene).
Active Layer 11
[0029] The active layer 11 is for example a disk-shaped layer, with
an inner face 11a, an outer face 11b, and a circumferential edge
11c. The active layer 11 is positioned inside the recess 103 of the
closure shell 10 and is entirely contained in the recess 103. More
especially, the active layer 11 completely fills the recess 103
without protruding outside the recess 103, the thickness E of the
active layer 11 being substantially equal to the depth of the
recess 103. The inner face 11a of the active layer 11 (i.e. face
11a oriented towards the inside IN of the container) is thus flush
with the inner face 104a of the shoulder portion 104, and there is
no overlap of the active layer 11 outside the recess 103, and in
particular no overlap of the material of the active layer 11 onto
the inner face 104a of the shoulder portion 104.
[0030] The outer face 11b and the circumferential edge 11c of the
active layer 11 are in contact with, and are bonded to,
respectively the bottom wall 103a and lateral wall 103b of the
recess 103 of the shell 10. The active layer 11 is preferably only
thermal bonded to the shell 10, i.e. without using an additional
adhesive layer in-between.
[0031] The active layer 11 is capable of chemically reacting with
water and generating molecular hydrogen from this reaction with
water. The material of the active layer 11 can be made of or can
comprise any active substance forming such a hydrogen source.
Preferably, but not only, said active substance suitable for the
release of molecular hydrogen as a result of contact with water is
one of the active substances described in PCT application
WO2008/090354.
[0032] In one preferred embodiment, the material of the active
layer 11 comprises a polymeric matrix containing the active
substance which is incorporated in the polymer matrix and which is
capable of chemically reacting with water and generating molecular
hydrogen from this reaction with water.
[0033] Suitable polymeric matrix materials include but are not
limited to low density polyethylene, in particular linear low
density polyethylene, high density polyethylene, polypropylene,
ethylene vinyl acetate, thermoplastic elastomers (TPEs), like
styrenic block copolymers, polyolefin blends, elastomeric alloys,
thermoplasticpolyurethanes, thermoplastic copolyester, and
thermoplastic polyamides, or blend thereof. In particular a good
candidate among thermoplastic elastomer materials is a material
comprising styrenic block copolymers consisting of polystyrene
blocks and rubber blocks, such as for example SEBS, SEPS, SBS,
SBC.
[0034] The ratio of the weight of active substance to matrix
material may be at least 0.01, preferably at least 0.02. The matrix
may be a polymeric matrix and said active substance may be
dispersed therein. In general, once an active material is dispersed
into a polymer, the rate of release of hydrogen is limited by
either the permeation rate of water into the polymeric matrix
and/or by the solubility of water in the chosen matrix. Thus,
selection of polymeric materials based on the permeability or
solubility of water in the polymer allows one to readily control
the rate of release of molecular hydrogen from any number of active
substances.
[0035] The polymeric matrix may include at least 1 wt % of active
substance, preferably at least 2 wt %. The polymeric matrix may
include less than 20 wt % of active substance. Suitably, the
polymeric matrix includes 1-16 wt %, preferably 4-12 wt % of active
substance. The balance of material in the polymeric matrix may
predominantly comprise a said polymeric material.
[0036] Active substances suitable for the release of molecular
hydrogen as a result of contact with water are preferably the ones
described in PCT application WO2008/090354. In particular, said
active substance may comprise a metal and/or a hydride. Said metal
may be selected from sodium, lithium, potassium, magnesium, zinc or
aluminum. A hydride may be inorganic, for example it may comprise a
metal hydride or borohydride; or it may be organic.
[0037] More particularly, active substances include but are not
limited to: sodium metal, lithium metal, potassium metal, calcium
metal, sodium hydride, lithium hydride, potassium hydride, calcium
hydride, magnesium hydride, sodium borohydride, and lithium
borohydride.
[0038] Where the rate of reaction between the active substance and
water is too slow, the addition of hydrolysis catalysts and/or
agents in the polymeric matrix can be used. For example, the rate
of hydrolysis of silicon hydrides may be enhanced by the use of
hydroxide or fluoride ions, transition metal salts, or noble metal
catalysts.
[0039] The active substance may also be the polymeric matrix. For
example, polymeric silicon hydrides such as
poly(methylhydro)siloxane provide both a polymeric matrix and an
active substance capable of releasing molecular hydrogen when in
contact with moisture.
Liner 12
[0040] The liner 12 is closing the recess 103 of the shell 10. The
liner 12 is in contact with and is bonded to the inner face 11a of
the active layer 11 and to the shoulder portion 104 of the shell 10
on the whole periphery of the active layer 11.
[0041] In this particular variant of FIG. 1, the liner 12 is also
in contact with and is bonded on its whole periphery to the
internal sealing lip 102a of the closure shell 10. This
characteristic is however not mandatory.
[0042] When the closure cap 1 is fitted onto a container C, this
liner 12 is facing the inside IN of the container C, and forms a
protective barrier that prevents the product stored in the
container from contacting the active layer 11 and that prevents the
active substance (H.sub.2 generator) of the active layer 11 from
migrating into the container. This liner 12 also to limit the
ingress of water in contact with the active layer 11, and thereby
enables to obtain a controlled release of molecular hydrogen by the
active layer 11 over a prolonged period of time.
[0043] Preferably, the liner 12 is only thermal bonded to the
active layer 11 and to the shell 10, i.e. without using an
additional adhesive layer.
[0044] The liner 12 can be a monolayer or a multilayer component.
The material of the liner 12 is preferably selected in order to
obtain a liner 12 that: [0045] (i) is heat bondable to the closure
shell and to the active layer 11, and [0046] (ii) is permeable to
water vapour and to molecular hydrogen.
[0047] The material of the liner 12 can be any polymeric material
that enables to obtain characteristics (i) and (ii). The materials
of the liner 12 include but are not limited to low density
polyethylene, in particular linear low density polyethylene, high
density polyethylene, polypropylene, ethylene vinyl acetate,
thermoplastic elastomers (TPEs), like styrenic block copolymers,
polyolefin blends, elastomeric alloys, thermoplasticpolyurethanes,
thermoplastic copolyester, and thermoplastic polyamides, or blend
thereof. In particular a good candidate among thermoplastic
elastomer materials is a material comprising styrenic block
copolymers consisting of polystyrene blocks and rubber blocks, such
as for example SEBS, SEPS, SBS, SBC.
Bonding of the Liner 12 with the Closure Shell 10
[0048] An efficient bonding between the liner 12 and the closure
shell 10 is very important, in order to avoid delamination problems
that would detrimentally lead to a risk of leakage and contact of
the active layer 11 with the product stored in the container, and
thereby to a risk of contamination of the product.
[0049] This efficient bonding is preferably obtained by using
materials for the closure shell 10 and the liner 12 that are
compatible in terms of thermal bonding, and that enable to achieve
a very good thermal bonding of the liner 12 with the shell 10. To
this end, the material of the liner 12 and the material of the
closure shell 10 comprise, or are made of, at least one identical
polymer. The material of the liner 12 can however be a polymeric
material that differs from the material of the closure shell 10. In
a preferred embodiment, the closure shell 10 was for example in
HDPE and the liner 12 was a monolayer liner made of EVA or LLDPE or
a thermoplastic elastomer comprising polyolefin blends or SEBS
blends.
[0050] This efficient bonding is also improved by the particular
structure of the closure cap with a recess 103 containing the
active layer 11 and with a shoulder peripheral bonding portion 104.
Thanks to the recess 103, the active layer 11 does not exert onto
the liner 12 a mechanical action that would contribute to
delaminate the liner 12 from the closure shell 10. The width (I) of
the shoulder bonding portion 104 (FIG. 1) will be selected by one
skilled in the art in order to obtain a sufficient bonding area
between the liner 12 and the shell 10, and to avoid any risk of
delamination during normal use.
[0051] FIGS. 2 to 6 show other variants for the closure cap.
[0052] In the variant of FIG. 3, the top wall 100 of the shell 10
comprises a recess 103, but in contrast with the variant of FIGS.
1, 2, 4, 5 and 6, does not comprise a shoulder bonding portion 104
for bonding the liner 12 to the shell 10. In this variant, the
liner 12 is bonded to the shell only on its circumferential edge
12a.
[0053] When the liner 12 is in contact with the internal sealing
lip 102a (like for example in the variants of FIGS. 1 and 2), there
is a risk that the liner 12 exerts a mechanical constraint on the
lips that leads to a deformation of the lip 102a. Such a
deformation can provoke leakage problems when the cap is fitted
onto a container. To avoid this problem, in the variants of FIGS. 4
to 6, the liner 12 is advantageously not in contact with the
internal sealing lip 102a, and there is a gap G between the
circumferential edge 12a of the liner 12 and the internal sealing
lip 102a.
Manufacturing Process
[0054] The closure 1 can be for easily and quickly manufactured by
using an over injection technique.
[0055] In a first step, the closure shell 10 is injection moulded
in a mould. In a second step, the active layer 11 is over injected
onto the closure shell. Then in a third step, the liner 12 is over
injected onto the closure shell 10 and active layer 11.
[0056] During injection, the active layer 11 is compressed in the
injection mould. When this mould is opened, a decompression of the
active layer 11 can occur. In such a case the active layer 11
exerts on the liner 12 a pressure that pushes the liner 12 away
from the shell 10. The bonding of the liner 12 is thus less strong,
which can lead to detrimental delamination problems. To solve this
problem, especially (but not only) when the active layer 11
comprises a thermoplastic elastomer, it is preferable that the
hardness of the active layer 11, for example measured with a
durometer according to ASTM D2240, is not less than Shore A
hardness 40.
O.sub.2 Scavenging
[0057] In use, when the container C is containing a product, in
particular an oxygen-sensitive product, and is closed by the
closure cap 1, the liner 12 avoids any contact between the active
layer 11 and the product stored in the container C. The water
vapour contained in the head space of container penetrates through
the liner 12 and enters in contact with the active layer 11.
[0058] As a result, the active substance of the active layer 11
produces molecular hydrogen that migrates through the liner 12 and
penetrates in the container head space. This molecular hydrogen
combines with oxygen which may have entered in the container
through its permeable wall. As a result a reaction between hydrogen
and oxygen takes place, and water is produced. This oxygen
scavenging reaction can be catalysed by a catalyst incorporated in
the closure cap 1 and/or in the container wall and/or in the
container neck.
[0059] A large number of catalysts are known to catalyze the
reaction of hydrogen with oxygen, including many transition metals,
metal borides (such as nickel boride), metal carbides (such as
titanium carbide), metal nitrides (such as titanium nitride), and
transition metal salts and complexes. Group VIII metals are
particularly efficacious. Of the Group VIII metals, palladium and
platinum are especially preferred because of their low toxicity and
extreme efficiency in catalyzing the conversion of hydrogen and
oxygen to water with little or no byproduct formation. The catalyst
is preferably a redox catalyst.
[0060] Preferably, but not necessarily, for facilitating the
recycling of the closure 1, the closure cap 1 has a density less
than 1, and the closure shell 10, the active layer 11, and the
liner 12, have respectively three different colours in order to
visually differentiate them. This is obtained for example by adding
a first colorant (for example red) to the polymeric material of the
active layer 11, and by adding a different colorant (for example
blue) to the polymeric material of the liner 12, the shell 10
containing for example no colorant and being substantially white.
The addition of colorant can be performed prior to injection or
during the injection of closure cap components. In a variant, a
third colorant (for example green) can be also added to the
polymeric material of the shell 10.
* * * * *