Scavenging oxygen

Abstract

A closure 40 for a container body includes a liner 46 which incorporates a hydrogen generating device comprising a hydride which generates hydrogen on contact with moisture. The liner may be an interference fit within the body 42. The liner 46 and other liners described may include control means for controlling passage of moisture to the hydrogen generating means and/or sealing means for sealing the closure to a container. In use, with the closure secured to a container, water vapor passes into liner 46 and contacts the hydride which generates hydrogen. A reaction between hydrogen and oxygen which has passed into the container takes place, catalysed by a catalyst, and water is produced. Thus, oxygen is scavenged.

Claims

1. A closure for a container body, the closure comprising a hydrogen generating means which includes an active material arranged to generate molecular hydrogen on reaction with moisture, wherein said hydrogen generating means comprises a matrix material in which said active material is embedded, wherein said hydrogen generating means is in combination with a control means for controlling passage of moisture to the hydrogen generating means, wherein said control means is arranged to control passage of moisture so as to reduce the rate of hydrogen generation by said hydrogen generating means compared to the rate in the absence of said control means, wherein said control means comprises a layer of material having a water vapour permeability of less than 2.0 g.mm/m.sup.2.day, and wherein said hydrogen generating means is capable of generating hydrogen for a period of time of at least 1 month.

2. A closure as claimed in claim 1, wherein said control means comprises a plurality of layers which are secured to one another and make face to face contact.

3. A claim according to claim 1, wherein the rate of passage of moisture through the control means, towards the hydrogen generating means, is slower than the rate of passage of water through said matrix material of said hydrogen generating means.

4. A closure according to claim 1, wherein the ratio of the permeability in g.mm/m.sup.2.day of the control means to the water permeability of the matrix material is 1 or less.

5. A closure according to claim 1, wherein the control means comprises a material which has a water vapour permeability in g.mm/m.sup.2.day which is less than the water vapour permeability of a polymeric matrix material present in the greatest amount in said matrix material.

6. A closure according to claim 1, the control means defines the rate determining step for passage of moisture to the active material of the hydrogen generating means.

7. A closure according to claim 1, wherein said hydrogen generating means has a length of at least 20 mm.

8. A closure according to claim 1, wherein said matrix material comprises a polymeric matrix material selected from polyolefins, low density polyethylene, high density polyethylene, polypropylene, styrene-ethylene-butylene (SEBS) copolymers, Nylon 6, styrene, styrene-acrylate copolymers and ethylene vinyl acetate.

9. A closure for a container body, the closure comprising a hydrogen generating means which includes an active material arranged to generate molecular hydrogen on reaction with moisture, wherein said hydrogen generating means comprises a matrix material in which said active material is embedded, wherein said hydrogen generating means is in combination with a control means for controlling passage of moisture to the hydrogen generating means, wherein said control means is arranged to control passage of moisture so as to reduce the rate of hydrogen generation by said hydrogen generating means compared to the rate in the absence of said control means, wherein said control means comprises a polymeric material selected from HDPE, PP, LDPE, PET, EVA, SEBS and Nylon, and wherein said hydrogen generating means is capable of generating hydrogen for a period of time of at least 1 month.

10. A closure as claimed in claim 9, wherein said control means comprises a plurality of layers which are secured to one another and make face to face contact.

11. A closure according to claim 9, wherein the rate of passage of moisture through the control means, towards the hydrogen generating means, is slower than the rate of passage of water through said matrix material of said hydrogen generating means.

12. A closure according to claim 9, wherein the ratio of the permeability in g.mm/m.sup.2.day of the control means to the water permeability of the matrix material is 1 or less.

13. A closure according to claim 9, wherein the control means comprises a material which has a water vapour permeability in g.mm/m.sup.2.day which is less than the water vapour permeability of a polymeric matrix material present in the greatest amount in said matrix material.

14. A closure according to claim 9, wherein the control means defines the rate determining step for passage of moisture to the active material of the hydrogen generating means.

15. A closure according to claim 9, wherein said hydrogen generating means has a length of at least 20 mm.

16. A closure according to claim 9, wherein said matrix material comprises a polymeric matrix material selected from polyolefins, low density polyethylene, high density polyethylene, polypropylene, styrene-ethylene-butylene (SEBS) copolymers, Nylon 6, styrene, styrene-acrylate copolymers and ethylene vinyl acetate.

17. A closure for a container body, the closure comprising a hydrogen generating means which includes an active material arranged to generate molecular hydrogen on reaction with moisture, wherein said hydrogen generating means comprises a matrix material in which said active material is embedded, wherein said hydrogen generating means is in combination with a control means for controlling passage of moisture to the hydrogen generating means, wherein said control means is arranged to control passage of moisture so as to reduce the rate of hydrogen generation by said hydrogen generating means compared to the rate in the absence of said control means, wherein said control means comprises a plurality of layers which are secured to one another and make face to face contact, and wherein said hydrogen generating means is capable of generating hydrogen for a period of time of at least 1 month.

18. A closure according to claim 17, wherein the rate of passage of moisture through the control means, towards the hydrogen generating means, is slower than the rate of passage of water through said matrix material of said hydrogen generating means.

19. A closure according to claim 18, wherein said matrix material comprises a polymeric matrix material selected from polyolefins, low density polyethylene, high density polyethylene, polypropylene, styrene-ethylene-butylene (SEBS) copolymers, Nylon 6, styrene, styrene-acrylate copolymers and ethylene vinyl acetate.

20. A closure according to claim 17, wherein the ratio of the permeability in g.mm/m.sup.2.day of the control means to the water permeability of the matrix material is 1 or less; and said control means defines the rate determining step for passage of moisture to the active material of the hydrogen generating means.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Specific embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, in which:

(2) FIG. 1 is a cross-section through a preform;

(3) FIG. 2 is a cross-section through a bottle;

(4) FIG. 3 is a side elevation of a bottle including a closure;

(5) FIG. 4 is a closure, partly in cross-section;

(6) FIGS. 5 to 10 are cross-sections through liners which may be incorporated into closures;

(7) FIGS. 11 to 20 are alternative closures, partly in cross-section.

(8) In the figures, the same or similar parts are annotated with the same reference numerals.

DETAILED DESCRIPTION

(9) A preform 10 illustrated in FIG. 1 can be blow molded to form a container 22 illustrated in FIG. 2. The container 22 comprises a shell 24 comprising a threaded neck finish 26 defining a mouth 28, a capping flange 30 below the threaded neck finish, a tapered section 32 extending from the capping flange, a body section 34 extending below the tapered section, and a base 36 at the bottom of the container. The container 10 is suitably used to make a packaged beverage 38, as illustrated in FIG. 3. The packaged beverage 38 includes a beverage. The beverage may be a carbonated beverage or non-carbonated beverage. Examples of suitable beverages include soda, beer, wine, fruit juices, and water. In one particular embodiment, the beverage is an oxygen sensitive beverage. In another embodiment, the beverage is a vitamin C containing beverage such as a vitamin C containing fruit juice, a beverage which has been fortified with vitamin C, or a combination of juices in which at least one of the juices includes vitamin C. In this embodiment, the beverage is disposed in the container 22 and a closure 40 seals the mouth 28 of container 22.

(10) Referring to FIG. 4, a circular cross-section closure 40 includes a body 42 with a screw-threaded portion 44 for screw-threadedly engaging the closure with threaded neck finish 26. Inwards of the portion 44 is a liner 46 comprising a hydrogen generating device which incorporates a hydride. The liner 46 is disc-shaped and is a friction fit within the body 42 of the closure which has a corresponding circular cross-section. Thus, the liner 46 is superimposed upon the circular cross-section, and its entire periphery extends to and contacts the circumferential wall of an inner part of the body 42 so that it effectively fills the inner part.

(11) As an alternative to it being a friction fit, the liner may be an interfence fit within the body 42 and/or may be secured by adhesive or other means. If an adhesive is used, then there is no requirement for the liner to fill the inner part of the body 42.

(12) The shell 24 of the container includes a catalyst. The catalyst may be dispersed in the polymer matrix, for example PET, which defines the shell 24 by injection molding polymeric matrix material and catalyst, for example a palladium compound, to define a preform 10 which is subsequently blow molded to define the container 22.

(13) In use, with container 22 including a beverage and closure 40 in position, the headspace in the container will be saturated with water vapor. This vapor passes into liner 46 and contacts the hydride associated with the liner. As a result, the hydride produces molecular hydrogen which migrates into the polymer matrix of shell 24 and combines with oxygen which may have entered the container through its permeable walls. A reaction between the hydrogen and oxygen takes place, catalysed by the catalyst, and water is produced. Thus, oxygen which may ingress the container is scavenged and the contents of the container are protected from oxidation. The scavenging effect may be maintained for as long as hydrogen is produced in the container and such time may be controlled by inter alia varying the amount of hydride in the liner.

(14) FIGS. 5 to 10 illustrate a range of different liners 46a to 46e which may be incorporated into the closure 40 of FIG. 4.

(15) Referring to FIG. 5, a three-layered liner 46a is shown which comprises an upper layer 50 which is arranged to make face-to-face contact with the inwardly facing wall 48 of the closure 40. Upper layer 50 may have multiple functions: it may be included to provide a gas barrier layer, and/or may be designed to be compressible by the introduction of any foamed construction and/or may be used to provide the structure with a smooth upwardly facing surface, and/or may be included to provide good adhesion to the inwardly facing wall 48. Optionally, upper layer 50 may be made from the same material as layer 56 if a symmetrical structure is required.

(16) Layer 54 comprises a foamed layer which incorporates a hydride and is therefore arranged to generate hydrogen as described herein. In some cases, the hydride may be arranged to act as a blowing agent in the production of the foamed layer and then remaining hydride may be used to generate hydrogen which is used in scavenging oxygen. The foam layer is compressible and is thereby arranged to facilitate sealing engagement of the liner 46a with an upwardly facing edge 29 of the container.

(17) Layer 56 has multiple functions. Firstly, it may act as a functional barrier layer, separating the active material from the beverage. Secondly, it may act as a moisture gate (e.g. a control means hereinbefore described) where the rate of moisture ingress through this layer impacts on the hydrogen evolution rate from the active material, in combination with the polymer matrix inside which the active material is encapsulated. Layer 56 should allow water vapour, molecular hydrogen and molecular oxygen to pass through but should preferably not allow any hydrogen generator/by-products to pass out into the beverage. Thirdly, layer 56 may act to provide the necessary surface friction characteristics between the free face of layer 56 and the upwardly facing edge 29 of the container to ensure that application and removal torque properties are appropriate for the packaging.

(18) Optionally, any one or layers 50, 54 and 56 may include a catalyst for catalysing the reaction between hydrogen and oxygen. Where a catalyst is included, it may be located in the layer(s) closer to the moisture source.

(19) Referring to FIG. 6, layer 50 is as described with reference to FIG. 5. Layer 58 comprises an active hydride material encapsulated within a polymer matrix. This layer could also incorporate a catalyst for catalysing the reaction between hydrogen and oxygen. In this case, a closure incorporating liner 46b would provide all the components required for an oxygen scavenging reaction. The matrix polymer could be a variety of species, preferably LDPE or EVA.

(20) Layer 60 is a foamed wadding layer. The wadding could be of any foam, fibre or elastic material that provides an opposing force to press against the edge 29 of the container on which the closure is to be sealed. Selection of appropriate wadding is important in providing an adequate seal. The wadding material may be a foamed PE. This wadding material layer could have the hydrogen generator component incorporated through it during the manufacturing process. Azodicarbonamide or sodium-bicarbonate are common blowing agents which could be used to produce the foamed wadding layer. The density of the foam could be adjusted by altering the amount of foaming agent added or the heat settings at which the material is processed and hence the reaction takes place. It would also be possible to use an EVA foam in this layer.

(21) The location, thickness and composition of the wadding layer 60 modifies the hydrogen gas release properties from the active layer (e.g. it may act as a control means as hereinbefore described).

(22) The arrangements of FIGS. 7 and 8 includes other combinations of layers 50, 56, 58 and 60.

(23) The arrangement of FIG. 9 includes other combinations of layers 56 and 60. This arrangement may be used as a container insert which may be fixed to the container wall. The arrangement of FIG. 10 includes other combinations of layers 50, 58 and 60.

(24) The liners 46a to 46d may be made by co-extrusion to form sheet materials from which disc-shaped (or other shaped as appropriate) liners may be punched out. It is preferred that adjacent layers are compatible so they may adhere to one another during co-extrusion. If the layers are not compatible, appropriate tie layers may be used leading to structures with an increased number of layers.

(25) The closures and liners of FIGS. 4 to 10 are suitably for use with wine bottles. The closure itself may be modified from that shown in FIG. 4 to include a depending skirt 62 (FIG. 11) which is attached to body 42 via a circumferential weakened portion 64. The FIG. 11 closure is fitted to a bottle so that the body 42 can be unscrewed from the bottle so as to break the weakened portion and leave the skirt, which is restricted from moving by cooperation with part of the bottle neck, in position on the bottle.

(26) The body 42 and/or skirt 62 may be made from metal and/or plastics.

(27) Closures for aseptic and hot fill applications have different requirements to those needed in wine applications. The closures tend to be much wider (33-43 mm) and the industry has moved away from liners in the closures. One reason for this was due to issues with sterilising the closures because the space behind the liner provided an opportunity for the sterilisation medium to remain present in the system. A further reason was to avoid the expense of having a separate liner material.

(28) A variety of closure designs have been developed in order to provide adequate sealing without the need for a liner material, as described below with reference to FIGS. 12 to 16.

(29) In the FIGS. 12 to 16 embodiments, the active materials are secured to the interior of the cap by compression moulding or multistep injection moulding the active matrix compound into the closure shell in situ. The molded design may be a mono- or multi-layer design.

(30) FIG. 12 shows a closure 70a comprising a closure shell 72 into which a compression molded liner 74 has been inserted. The liner 74 has active material incorporated into a thermoplastic elastomer which is typically used in such applications e.g. SEBS. The active material (which is suitably a hydride) may be added as a dispersion in oil. The oil used may be used to modify the physical characteristics and softness of the SEBS. The advantage of this approach is that the liner can be molded on standard compression molding equipment with minimal operational changes.

(31) FIG. 13 shows an over-molded dual compression design. A thermoplastic elastomer such as SEBS is the matrix polymer used in both layers 76, 78. However, the active first layer or insert 76 (which incorporates a hydride) could be made from an alternative polymer matrix such as LDPE. The outer layer 78 should be made from a compressible material, in order to retain the sealing characteristics against edge 29 of the container.

(32) The insert 76 is molded first, followed by a second stage where the over-layer 78 is molded. An advantage of this design is that the active hydride material in layer 76 is protected by a functional barrier in layer 78. The thickness and composition of the first layer 76 controls the hydrogen release rate and hence shelf-life.

(33) FIG. 14 is similar to FIG. 13 except that a catalyst component is incorporated into the overmolded layer 78a. In this case, the rate determining step for hydrogen evolution is a function of moisture ingress to the active insert 76. Reaction between hydrogen and oxygen occurs in the overmolded layer 78a.

(34) FIG. 15 shows how a compression molding technique is flexible in allowing modification of the central portion 76a of the liner construction. The peripheral sealing edge 80 remains the same but the domed shape allows the incorporation of a greater amount of active material into the structure.

(35) FIG. 16 shows an aseptic closure shell with a sealing well 82. The active material is positioned in a layer 76b within the diameter of the sealing well 82. The materials used in this construction must be resistant to the sterilisation process used (typically washing with peracetic acid/hydrogen peroxide solution). Suitably, there are no areas within the design that allow small amounts of the sterilisation medium to remain within the structure to cause contamination to the packaged foodstuff. Furthermore, materials used should not cause contamination of the sterilisation medium. As HDPE is a commonly used material for this style of closure shell, LDPE would be a preferred polymer matrix material for layer 76b. The active material in layer 76b may be overmolded with a polymer layer 84 to prevent migration.

(36) FIG. 17 does not incorporate a functional barrier but includes unprotected layer 76c which includes active hydride material within matrix polymer. The arrangement would be used in applications where direct food contact for layer 76c was approved.

(37) In the FIGS. 16 and 17 embodiments, the inserts 76 may fully or (as shown in the figures) partially fill the wells 82.

(38) FIG. 18 is a multilayer construction whereby the material of the closure shell 72a itself is used as a barrier material. The active material within a matrix is present as a central portion 76d within the closure shell construction. The active material is preferably only present in a circular region of the closure shell as the material would be wasted if it were incorporated into the sides of the design.

(39) FIGS. 19 and 10 both show designs suitable for the oxygen barrier and carbon dioxide retention properties required for beverages such as beer or carbonated soft drinks. Typically, closures for such applications incorporate pre-molded disks of a barrier polymer such as PVC to prevent CO.sub.2 loss. The active hydrogen-generating material can be incorporated into the same liner material 84. FIG. 19 shows such a liner 84 which has been push-fitted into the closure shell 72. FIG. 20 has a similar liner system except that it has been adhered to the closure shell using a suitable adhesive 86.

(40) As an alternative to liners or other structures incorporating active hydrogen generating material being friction or interference fitted into a closure shell, assemblies comprising hydrogen generating material may be fitted in position by other means. For example an upper internal wall of the closure shell may incorporate a projecting threaded bolt which may be arranged to cooperate with an opening defined in an assembly comprising hydrogen generating material in order to screw-threadedly secure the assembly in position.

(41) The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.