WO2004055131A1

WO2004055131A1 - Oxygen scavenging compositions with reduced colour

Info

Publication number: WO2004055131A1
Application number: PCT/AU2003/001674
Authority: WO
Inventors: Andrew Scully; Mark Horsham; James Murphy; Patricia AGUAS
Original assignee: Commonwealth Scientific and Industrial Research Organization CSIRO
Current assignee: Commonwealth Scientific and Industrial Research Organization CSIRO
Priority date: 2002-12-16
Filing date: 2003-12-16
Publication date: 2004-07-01
Anticipated expiration: 2005-06-16
Also published as: AU2002953364A0

Abstract

A method of scavenging oxygen in an atmosphere or liquid is described comprising the steps of: (i) treating benzophenone or a benzophenone derivative (or a salt thereof), or a composition including said benzophenone or benzophenone derivative (or salt thereof), with predetermined conditions so as to reduce the benzophenone or benzophenone derivative (or salt thereof) to a reduced state oxidisable by oxygen; and (ii) exposing the atmosphere or liquid to said composition;such that at least a portion of the oxygen in the atmosphere or liquid is removed through oxidation of the reduced state of the benzophenone or benzophenone derivative (or salt thereof). Packaging materials for use in the method of the invention are also described.

Description

OXYGEN SCAVENGING COMPOSITIONS WITH REDUCED COIOU

FIELD OF THE INVENTION:

This invention relates to a method of scavenging oxygen using compositions comprising benzophenone or benzophenone derivatives, for use in, for example, food and beverage packaging to scavenge unwanted oxygen, which either remains within the package following the packaging of the food or beverage or otherwise enters the package by permeating through the packaging material. The benzophenone or benzophenone derivative may also be incorporated into packaging materials, to prevent oxygen from permeating through the packaging material to enter the inside of a package.

BACKGROUND TO THE INVENTION:

A wide variety of foods, beverages and other materiats are susceptible to loss m quality if they are exposed to significant amounts of oxygen during storage. The damage can arise from, for example, chemical oxidation of the product and/or microbial growth. In the field of packaging, such damage has been traditionally addressed by generating relatively iow- oxygen atmospheres by vacuum packing and /or inert gas flushing. However, these methods are not generally applicable for various reasons. For example, the fast filling speeds commonly used in the food and beverage industries often prevent effective evacuation of, or thorough inert gas flushing of, food and beverage packages, and neither evacuation or inert gas flushing provides any residual capacity for removal of oxygen which may have desorbcd from the package contents or entered the package by leakage or permeation. As a consequence, there has been much interest in the identification and development of chemical techniques for generating low-oxygen atmospheres.

In Australian Patent No. 672661 (the entire disclosure of which is incorporated herein by reference), the present applicants describe novel oxygen scavenging compositions comprising a source of labile hydrogen or electrons and a reducible organic compound, which may be readily activated or "triggered" (ic brought to. its oxygen scavenging form) as required by exposure to, for example, ultraviolet (UV) light. The oxygen scavenging compositions, once activated, are capable of scavenging oxygen from an oxygenated atmosphere or liquid in substantial darkness for periods ranging from up to a few minutes or hours to over 100 days.

141595813 Most of the exemplified oxygen scavenging compositions described in Australian Patent No. 672661, are based on substituted anthraquinones as the reducible organic compound- Further examples of substituted anthraquinones suitable for use as the reducible organic compound in such oxygen scavenging compositions are disclosed in International Patent Application No- PCT/ AU02/ 00341 (WO 02/076916) (the entire disclosure of which is hereby incorporated by reference).

Substituted anthraquinones tend to be coloured in both the oxidised and reduced states. Compositions and packaging which contain such anthraquinones also tend to be coloured, for instance, films made using anthraquϊnone-based compositions are often a light yellow colour wliich turns deep yellow when the film is reduced to activate the oxygen scavenging capacity.

The coloured nature of the anthraquinone-based compositions is undesirable in many forms of packaging, particularly in the packaging of foodstuffs.

The present applicants have now identified a certain class of reducible organic compounds, namely benzophenones, that has the characteristic of having substantially less visible colour in at least the reduced state than other classes of reducible organic compounds that arc also useful for scavenging oxygen, such as anthraquinones.

DISCLOSURE OF THE INVENTION:

Thus, the present invention provides a method of scavenging oxygen (particularly ground state oxygen) in an atmosphere or liquid comprising the steps of:

(i) treating benzophenone or a benzophenone derivative (or a salt thereof), or a composition including said benzophenone or benzophenone derivative (or salt thereof), with predetermined conditions so as to reduce the benzophenone or benzophenone derivative (or salt thereof) to a reduced state oxidisable by oxygen; and

(ii) exposing the atmosphere or liquid to said composition;

such that at least a portion of the oxygen i the a mosphere or liquid is removed through oxidation of the reduced state of the benzophenone or a benzophenone derivative (or salt thereof).

141595813 Preferably the benzophenone derivative is a substituted benzophenone of formula I:

σ) wherein;

X¹, X², X³, X*, X⁵, X\ X⁷, X³, X^s and X^,D are each independently selected from H and L-R¹ provided that at least one of X X², X³, X\ X⁵, X⁶, X⁷, X⁸, X^y and X^,π is L-R¹ wherein L is sel cted from O and CH(R²) wherein R² is H or C_{r 0} alkyl, Oj, CO, CONH, SO₃, SO_j, or S0₂NH, and R^l is selected from H, C_rC₂₀ alkyl, C o alkoxy, C_rC₂₀ alkanoyl, C_j- _2U alkanol, Cι-C ₀ alkylamido, C ₂o alkylcarboxy, Cr alkylsulfonyl, C_t-C₂₀ alkylsulfonamido, sulfonate subεtituente, carboxylate substituents, C C₂₀ alkylammo, C_J-C_ΪO alkylmorpholino, - . alkylpiperazinyl, and the radicals represented by,

— CH₂— CH₂- OCH₂CH₂^rOH

wherein n is any integer between 1 and 20, Z¹ and Z² are selected from H, C.- m alkyl, T ζ 7 -C20 alkanol, C₁-C₂ aminoalkyl and \ / , and the radical represented by,

O

wherein 11 is as defined above, and ? is selected from C₁-C₂₀ alkanol, - oaminoal yl, Cι-C₂₀morpholinoalkyl, - npipera-inylalkyl, and the radical represented by,

141595813 :H₂— CH₂-f-0α4₂CH2- ₅OH

wherein n is as defined above;

or a compound of formula ΪI:

(II) wherein;

X¹, X², X³, X* X⁷, X^s, X⁹ and X^lfl are as defined above and wherein Y is not a carbonyl group and is preferably selected from S, O, NX¹¹ and CXⁿX¹² wherein X^H and X^l2 re selected from H and C,-C₂₀ alkyl. More preferably, Y is selected from NX¹¹ and CX Xⁿ.

The benzophenone and benzophenone derivatives for use in the method of the present invention arc substantially colourless or show reduced colour in at least the reduced state, but more preferably in both the reduced and oxidised states, relative to anthraquinones (particularly 2-ethylanthraquinθne). Preferably, when the method of the present invention uses a benzophenone derivative, the benzophenone derivative is selected such that in the reduced state it has a maximum absorbance in the visible spectrum (400nm - 700nm) that is no more than half that of 2-ethylanthraquinone under the same conditions.

The steps (i) and (ii) may be carried out in either order.

Step (i) may involve treatment of the benzophenone or benzophenone derivative (or salt thereof) with, for example, light of a certain intensity or wavelength (eg UV light) or, al ernatively, the application of heat, γ-irradiation, corona discharge or an electron beam. The reduced benzophenone or benzophenone derivative (or salt thereof) is reactive towards molecular oxygen to produce activated species such as hydrogen peroxide, hydroperoxy radical or a supcroxide ion.

14159581.. Where the benzophenone or benzophenone derivative (or salt thereof) or, alternatively, a composition including said benzophenone or benzophenone derivative (or Salt thereof), forms or is incorporated in a packaging material, the exposure of step (ii) may be effected by a step of packing a product (eg a food or beverage) within said packaging material, ϊn the case, where the packaging material is provided in the form of a container, the packing step may generate said atmosphere (eg generation of a "headspace").

Alternatively, or additionally, the benzophenone or benzophenone derivative i self may be in a polymerised form either as homopolymers or copolymers. Oligomer forms may also be suitable. Eenzophenone-based monomers can be made by covalently bonding an cthylenicaHy unsaturatcd group to one of the benzophenone phenyl rings. The

. benzophenone derivative may also carry groups, such as carboxylic acid, ester, anhydride, epoxy, hydr xy, and amine groups, capable of reaction with other polymerisable molecules and preformed polymers.

When the method according to the present invention employs a composition including said benzophenone or benzophenone derivative (or salt thereof), the composition preferably further comprises an activated oxygen scavenging agent (ie an agent which reacts with activated oxygen species such as peroxide). Suitable activated oxygen scavenging agents include organic antioxidants, organic phosphites, organic phosphines, organic phosphates, hydroquinone and substituted hydroquinone; inorganic compounds including sulphates, ^' sulphites, phosphi tes and nitrites of metals; sulphur-containing compounds including thiodipropionic acid and its esters and salts, t io-bis (ethylene glycol beta-aminocrotonate), cystcine, cystine and methionine; and nitrogen-containing compounds including primary, secondary and tertiary amines and their derivatives.

Compositions used in the method of the present invention may be in a solid, semi-solid (eg a gel) or liquid form. They may therefore be applied as, or incorporated in, for example, bottle closure liners, inks, coatings, adhesives (eg polyurethanes), films, sheets or layers in containers such as trays or bottles either alone or as laminations or co-extrusions. When used in films or layers, they may be blended with typical polymers or copolymers used for construction of films or layers such as those approved for food contact. Such films or layers may be produced by extrusion at temperatures between 50 °C and 350 °C depending upon chemical composition and molecular weight distribution.

141595S13 The benzophenone or benzophenone derivatives and compositions of the present invention can be used in any suitable application in which oxygen scavenging is required. Numerous specific applications, for instance, are disclosed in Australian Patent No. 672661 as well as in Australian Patent No. 758893 (the entire disclosure of which is incorporated herein by reference).

The terms "comprise", "comprises" and "comprising" as used throughout the specification are intended to refer to the inclusion of a stated step, component or feature or group of steps, components or features with or without the inclusion of a further step, component or feature or group of steps, components or features.

In the specification, unless stated otherwise, where a document, act or item of knowledge is referred to or discussed, that reference or discussion is not an admission that the document, act or item of knowledge, or any combination thereof, at the priority date, was part of the common general knowledge in the art in Australia or elsewhere.

The invention will now be described with reference to the following, non-limiting examples and accompanying figure(s).

BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURES:

Figure 1(a) provides absorption spectra of a film prepared according to the present invention before and after exposure to UV radiation.

Figure 1(b) provides comparative absorption spectra of a film prepared according to prior art methods before and after exposure to UN radiation.

EXAMPLES:

The compositions referred to in Examples 1 to 4 and 6 were prepared by blending benzophenone or the specified benzephenone derivative at a level of 2%w/ w into saponified EVA. The saponified EVA compositions used in Examples 1 to 4 and 6 were prepared by saponification of Evatane® 40-55. The compositions were then compression molded to form a film having a thickness of about 50 μ . This film was placed between two layers of polypropylene film and vacuum-sealed to form a fiat package Containing essentially no headspace. The package was placed on a conveyor belt moving at 10 m/min and then exposed to light from a commercial UN-curing lamp (model F-300 fitted with a

141595813 'D' bulb (Fusion Systems Corp., Maryland, USA)). After exposure to the lamp, the package was opened and the film was then quickly transferred into a foil multilayer bag, and this bag was then vacuum-sealed to form a flat package containing essentially no headspace. This foil-lined pouch allows essentially no ingress of oxygen from the atmosphere into the inside of the pouch. Air was then injected into the foil-lined pouch and the pouch stored at constan temperature. The oxygen content inside the pouch was measured by gas chromatography.

Example 1: Oxygen scavenging by a composition comprising benzophenone in saponified EVA

The change in oxygen concentration in three pouches prepared in the manner described above, and stored at 40 °C, is shown in Table 1. The films were substantially colourless and remained that way after exposure to oxygen.

Table 1.

Example 2: Oxygen scavenging by a composition comprising 2-isopropylbenzophenone ester in saponified EVA

The change in oxygen concentration in three pouches prepared in the manner described above, and stored at 25 °C, is shown in Table 2, The films were substantially colourless and remained that way after exposure to oxygen.

141595813 Table 2.

Exa ple 3: Oxygen scavenging by a composition comprising 3-methyIbenzophenone in saponified EVA

The change in oxygen concentration in three pouches prepared in the manner described above, and stored at 25 °C, is shown in Table 3- The films were substantially colourless and remained that way after exposure to oxygen.

Table 3.

141595813 Example 4: Oxygen scavenging by a composition comprising 4-methoxybenzophenone in saponified EVA

The change in oxygen concentration in three pouches prepared in the manner described above, and stored at 25 °C, is shown in Table 4. The films were substantially colourless and remained that way after exposure to oxygen.

Table 4.

Example 5: Oxygen scavenging by a composition comprising benzophenone in commercial EVOH

A composition was prepared by blending benzophenone into a commercially available EVOH (Soarnol® DC3212) at a level of 1.7%w/w. The composition was then compression molded to form a film having a thickness of about 50 μm. This film was placed between two layers of polypropylene film and vacuum-sealed to form a flat package containing essentially no headspace. The package was placed on a conveyor belt moving at 10 m/mi n and then exposed to light from a commercial UV-curing lamp (model F-300 fitted with a ^JΩ' bulb (Fusion Systems Corp., Maryland, USA)). After exposure to the lamp, the package was opened and the film was then quickly transferred into a foil multilayer bag together

141595813 with 1 ml of water to increase the rate of permeation of oxygen into the EVOH, and this bag was then vacuum-sealed to form a flat package containing essentially no headspace. This foil-lined pouch allows essentially no ingress of oxygen from the atmosphere into the inside of the pouch. Air was then injected into the foil-lined pouch and the pouch stored at 40 °C. The films were substantially colourless and remained that way after exposure to oxygen. The oxygen content inside the pouch was measured by gas chromatography. The change in oxygen concentration in two pouches prepared in the manner described is shown in Table 5.

Table 5.

Example 6: Substantial colour reduction

A composition was prepared by blending benzophenone at a level of 2%w/ w into saponified EVA. The composition was then compression molded to form a film having a thickness of about 50 μ . The absorption spectrum of this film before and after exposure to light from a commercial UV-curing lamp (bulb (Fusion Systems Corp., Maryland, USA; model F-300 fitted with a 'D') is shown in Figure ^"1(a).

141595813 A composition was prepared by blending 2-ethyIanthraquinone at a level of 2%w/ w into saponified ENA. The composition was then compression molded to form a film having a thickness of about 50 μm. The absorption spectrum of this film before and after exposure to light from a commercial UV-curing lamp (bulb (Fusion Systems Corp., Maryland, USA; model F-300 fitted with a 'D') is shown in Figure 1 (b).

The maximum absorbance in the visible spectrum (400-700nrn) or the film containing the reduced ben2θphenone is less than half that of the film containing the reduced 2- ethylanthraquinone.

It will be appreciated by persons skilled in the art that numerous variations and/ or modifications may be made to the invention as shown in the specific embodiments ithout departing from the spirit or scope of the invention as broadly described. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.

141595813

Claims

CLAIMS:-

1. A method of scavenging oxygen in an atmosphere or liquid comprising the steps of:

(ii) exposing the atmosphere or liquid to said composition;

such that at least a portion of the oxygen in the atmosphere or liquid is removed through oxidation of the reduced state of the benzophenone or benzophenone derivative (or salt thereof), and wherein steps (i) and (ii) can be carried out in cither order.

2. A method according to claim 1 wherein the benzophenone derivative is a substituted benzophenone of formula T:

CD wherein;

X¹, X², X³, X⁴, X⁵, X⁶, X⁷, X^s, X^<J and X"* are each independently selected from H and L-R¹ provided that at least one of X¹, X², X^a, X", X^s, X^a, X⁷, X^s, X⁹ and X^1Q is L-R¹ wherein L is selected from O and CH(R ) wherein R² is H or d- α alkyl, COj, CO, CONH, SO,, SO* or S0₂NH, and R¹ is selected from Ii, - o alkyl, C_rC_M alkoxy, C_{r 0} alkanσyl, C C_M alkanol C,-C_7α alkylamido, C Cioal ylc rb xy, C,- o alkylsulfonyl, Q- π alkylsulfonamido, sulfonate substituents, carboxylate substituents, C^Czo alkylaminσ, C_rC_2l)alkylmorpholino, - oalkylpiperazinyl, and the radicals represented by,

141595813 — CH₂— CH₂- OCH₂CH₂^OH

wherein n is any integer between 1 and 20, Z¹ and 2? are selected from H, C C_2Q alkyl,

' CH " — 7

Cj-C₂₀ alkanol, Cj-C_2Daminoalkyl and ² \ / , and the radical represented by,

— CH₂— CHz- OCHaCHz^OH

5 wherein n is as defined above, and Z³ is selected from Cj-C_m alkanol, -C^oaminoalkyl, CrC₂₀morpholinoalkyl,

and the radical represented by,

— CH₂— CH₂- OCH₂CH₂-V)H

wherein n is as defined above.

^"10 3. A method according to claim 2 wherein L is selected from O and CH(R^Z) wherein R² is H or C- o alkyl, COj, CONH, or SO_zNH, and R¹ is selected from H, C,-C_2n alkyl, C C_a, alkoxy, C C_Z0 alkanoyl, C|-C_2v alkanol, C _o alkyla tdo, - o alkylcarboxy, CrC₂₀ alkylsulfonyl, C C_2ϋ alkylsulfonamido, sulfonate substituents, carboxylate substituents, and C.- j_D alkyl a ino. .

15 4. A method according to claim 2 wherein L is selected from O and CH(R²) wherein R² is H or - u alkyl, or O2, and R¹ is selected from H and Cr o alkyl.

5. A method according to claim 1 wherein the benzophenone derivative is a compound of formula II:

141595813

(II) wherein;

X¹, X³, X³, X⁴, X⁷, X", X⁹ and X¹⁰ are each independently selected from H and L-R¹ provided that at least one of X¹, X², X^s, X*, X⁷, X^B, X⁹ and X¹⁰ is L-R¹ wherein L is selected from O and CH(R^a) wherein R² is H or C_rC₂₀ alkyl, CO*, CO, CONH, SO_j, SO;,, or S0₂NH, and R¹ is selected from H, C_rC_m alkyl, C_rC_ω alkoxy, C_rC₂₀ εdkanoyl, r n alkanol, -Cai alkylamido, C,-C_2D alkylcarboxy, C,-C₂o alkylsulfonyl, C,-C₂₀ alkylsulfonamido, sulfonate substituents, carboxylate substituents, - oalkylεmύno, C C₂₀ alkylmojpholino, CrC_2n alkylpiperazinyl, and the radicals represented by,

— CH₂— CH₂- OCH₂CH₂-)^ H

wherein n is any integer between 1 and 20, Z¹ and Z² are selected from H, - . alkyl,

C--C₂₀ alkanol, -C₂₀ aminoalkyl and ² \ 7 , and the radical represented by,

-CH₂— CH₂- OCH₂CH₂-^ H

wherein n is as defined above, and Z³ is selected from C_rC₂₀ alkanol, CrC₂₀ aminoalkyl, CrC_2nn-ιorpholinoalky], Cj- iperazinylalkyl, and the radical represented by,

— CH₂— CH₂- OCH₂CH₂ rOH

^•141395813 wherein n is as defined above;

and wherein Y is not a carbonyl group and is selected from S, O, NX¹¹ and CX^UX¹² wherein Xⁿ and X¹² are selected from H and C_rC₂₀ alkyl.

6. A method according to claim 5 wherein L is selected from O and CH(R²) wherein R² is H or C_rC _u alkyl, C0₂, CONH, or S0₂NH, and R' is selected from H, C,-C» alkyl, C,-C_2tl alkoxy, C_rC₂₀ alkanoyl, C,-C_χn alkanol, C_τ-C_lu alkylamido, - o alkylcarboxy, C_t-C_ffl alkylsulfonyl, -C₂₀ alkylsulfonamido, sulfonate substituents, carboxylate substituents, and CrC₂₀alkylarπino.

7. A method according to claim 5 wherein L is selected from O and CH(R²) wherein R^z is H or C_ΓQ_JO alkyl, or C0₂, and R¹ is selected from H and C,-C₂₀ alkyl.

8. A method according to claim 7 wherein Y is selected from NX¹¹ and CXⁿX^,z.

9. A method according to any one of claims 1 to 8 wherein the benzophenone or benzophenone derivative is in a polymerised or oligomerised form.

10. A method according to any one of claims 1 to 9 wherein the benzophenone or benzophenone derivative in the reduced state is selected to be colourless or show reduced colour relative to 2-ethylanthraquinone.

11. A method according to claim 10 wherein the benzophenone or benzophenone derivative in the oxidised state is selected to be colourless or show reduced colour relative to 2-ethylanthraqu one.

12. A method according to any one of claims 1 to 9 wherein the benzophenone or benzophenone derivative is selected such that in the reduced state it has a maximum absorbance in the visible spectrum (400nm-700nm) that is no more than half that of 2-ethylanthraquinone under the same conditions.

13, A method according to any one of claims 1 to ^"12 wherein the benzophenone or benzophenone derivative is in a composition further comprising an activated oxygen scavenging agent.

14. A method according to claim 13 wherein the activated oxygen scavenging agent is selected from the group consisting of organic antioxidants, organic phosphites, organic

1-11595813 lfe phosphines, organic phosphates, hydroquinone and substituted hydroquinone; inorganic compounds including sulphates„sulphites, phosphites and nitrites of metals; sulphur- containing compounds including fhiodipropionic acid and its esters and salts, thio-bis (ethylene glycol bcta-aminocrotonate), cystcine, cystine and mctliionine; and nitrogen- cont-uning compounds including primary, secondary and tertiary amines and their derivatives.

15. A method according to any one of claims 1 to 14 wherein the predetermined condi tions of step (i) are selected from the group consisting of light of a certain intensity or wavelength, the application of heat, γ-irradiation, corona discharge and an electron beam.

16. A method according to claim 15 wherein the light of a certain intensity or wavelength is UN light.

17. A method according to any one of claims 1 to 16 wherein the benzophenone or benzophenone derivative (or salt thereof) or the composition including said benzophenone or benzophenone derivative (or salt thereof), for s or is incorporated in a packaging material.

141595813