MXPA00004994A - Oxygen scavenging hydrotalcite and compositions containing same - Google Patents

Abstract

An oxygen scavenging agent and compositions capable of providing good oxygen absorption capabilities which contain said agent, wherein the agent is a modified anionic hydrotalcite particulate material.

Description

HYDROTALCITA OXYGEN DEPURATOR AND COMPOSITIONS THAT CONTAIN IT BACKGROUND OF THE INVENTION The present invention relates to a novel agent and the resulting compositions that can be used to preserve the quality of a product and improve the shelf life of oxygen-sensitive materials, and molded, intermediate structures, for example, films, coatings, three-dimensional solids, fibers, continuous materials and the like containing the composition as well as the products molded in or on which the composition or structure is incorporated or applied to be part or be attached to the structure of the container. The present agent is a hydrotalcite, anionic, modified particulate. It can be formed in a composition containing the agent in a carrier that allows the agent to combine with oxygen when it is in the presence of moisture. Specifically, the composition utilizes anionic, modified hydrotalcite-like particles having certain anionic groups, as fully described hereinbelow. The particulate containing the oxygen scavenging composition of the present invention has unexpectedly been found to provide effective oxygen uptake from the interior of a container without adversely affecting the color, taste and odor of the packaged products contained therein, which they are usually associated with traditional agents and / or byproducts of their oxidation. The present oxygen scavenging composition has the ability to chemically and efficiently combine with the oxygen in contact therewith, such as from within a container, without undue migration of the oxygen scavenger or its byproducts (s) from oxidation outside. of the matrix of the composition. The inhibition of migration is of particular advantage in that it significantly reduces or eliminates the adverse effects on the color, taste or odor of the articles in contact with the matrix composition as well as provides a means of using high levels of the purifying agent fulfilling at the same time the governmental regulations directed to the amounts of foreign material allowed in the food products. To improve preservation, it is normal practice to pack food and other materials into laminated packaging materials that generally include a barrier layer, i.e., a layer having a low oxygen permeability. The laminate material may be thin, in which case it is wrapped around the material being packaged, or may be thick enough to form a molded container body that is provided with a lid or other separate closure. The polymeric laminate material may constitute some or all of the interior of the exposed surface area of the container or its closure means. The inclusion of an oxygen scavenger in the laminate is known. The oxygen scavenger reacts with oxygen that is trapped in the package or that permeates the package. This is described in, for example, U.S. Patent No. 4,536,409, and 4,702,966 and the prior art described in these references. U.S. Patent No. 4,536,409, for example, discloses cylindrical containers formed of such laminated material and provided with metal caps. When the container is formed of a vitreous or metallic body and is provided with a hermetically sealed metallic closure, the permeation of oxygen through the body and the closure theoretically is impossible due to the impermeability of the materials forming the body and the closure. As a practical matter, metal cans can reliably prevent the ingress of oxygen. However, some oxygen ingress may occur by diffusion through the board or the like placed between a body of the container and its lid. It has been recognized that when traditional containers of these types are used for storage of oxygen sensitive materials, the storage life of the stored materials is very limited. The quality of the packaged material tends to deteriorate over time, in part because dissolved oxygen is usually present in the package from the moment of filling; and partly because oxygen enters during storage. When the container is in the form of a can, the end of the can and other closure in many cases include pushing components or pulling components that are proposed to be, respectively, pushed or dragged to allow the removal of the fluid or other material in the container without removing the entire closure of the container. These push and pull components are often defined by discontinuities or lines of weakness in the closure panel. Problems that may arise in these lines of weakening or discontinuities include the risk of oxygen permeation to the container and the risk of corrosion of the metal where the coating of the normal protective lacquer breaks in weakening lines or discontinuities. It would be very desirable to be able to significantly improve the life in storage and to continue using the traditional materials for the formation of the body of the container, the closure of the container and, where applicable, the joint between the body and the closure.

Different types of oxygen scavengers have been proposed for this purpose. For example, it is well known to pack iron powder in a small bag for use with dehydrated foods. See Mitsubichi Gas Chemical Company, Inc. Literature of the company entitled "Ageless® -A New Age in Food Preservation" (date unknown). However, these materials require the addition of water-soluble salts to improve the oxygen purification rate and, in the presence of moisture, the salts and iron tend to migrate towards the liquids, producing flavor detachment. In the same way, U.S. Patent No. 4,536,409 published by Farell et al. Recommends potassium sulfite as a scavenger, with similar results. U.S. Patent No. 5,211,875 published by Speer et al., Discloses the use of unsaturated hydrocarbons for use as oxygen scavengers in packaging films. It is known in the art that the ascorbate compounds (ascorbic acid, its alkali metal salts, optical isomers and derivatives thereof) as well as sulfites, bisulfites, phenolics, etc., can be oxidized by molecular oxygen and thus can be as an oxygen scavenger material, for example, as a component of a closed compound. For example, U.S. Patent No. 5,075,362, published by Hofeldt et al., Discloses the use of ascorbate compounds in container closures as oxygen scavengers. U.S. Patent No. 5,284,871 published by Graf relates to the use of an oxygen scavenger composition prepared from a solution of a reducing agent and dissolved copper species that are mixed in foods, cosmetics and pharmaceuticals. Copper ascorbate is used in the examples. The reference indicates that the relatively high concentration of Cu 2+ (~ 5 ppm) is required in the feed for the purification to be effective 2+ but indicates that small amounts of Cu can be combined with the oxygen in the feed to cause decomposition thereof. . To avoid decomposition, it is necessary to reduce the amount of O2 in the upper space or partially flood the container with an inert gas (column 5, lines 32-39). A document by E. Graf, "Copper Ascorbate (II): A Novel Food Preserving System ", Journal of Agricultural Food Chemistry, vol., 42, pages 1616-1619 (1994) identifies copper gluconate as the preferred material. It is also well known in the scientific literature (see "Polymer Compositions Containing Compounds Oxygen Scrubbers ", Teu Ac, NF; et al., WO 91/17044 published November 4, 1991, filed May 1, 1991) that the oxidation rate of ascorbate compounds can be significantly increased by the use of catalysts The common oxidation catalysts for ascorbic acid and its derivatives are water-soluble transition metal salts.When these catalysts are combined with an ascorbate compound in a polymeric matrix, for example, a formulation for PVC closure, these They are effective in catalyzing the oxidation of the ascorbate compound and increase the rate of oxygen scavenging of ascorbate.In each of the above references, the active component of oxygen scavenging systems uses agents that are easily transferred to the food. other products or materials packaged or that produce byproducts of oxidation that are known to adversely affect a wide range of material It is packed in. Hydrotalcite is a naturally occurring mineral, commonly classified as a clay. In general, clays are divided into broad groups of cationic materials that are commonly found in nature or anionic materials, which are rarely found in nature. These materials are used in a wide range of applications, such as industrial absorbers, catalysts, fillers, bleaching agents and the like. The natural hydrotalcite are hydroxide-carbonate minerals of the formula: Mg6Al2 (OH) 16C03 «4H20 It is well known that the hydrotalcite mineral is strongly bound to the carbonate. The carbonate can be released by thermal calcination. Recently, hydrotalcites with different carbonate anions have been synthesized. These are generally double stratified hydroxides (LDH) which include anionic hydrotalcite type compounds (HTLC). These have been described in U.S. Patents 5,399,329 and 5,507,980 as well as by W. T. Reiche in Chem Teach (1986) 58-63, the teachings of which are incorporated herein in their completeness as a reference. These materials have anions in their crystalline structure that are easily exchanged. Although the known HTLC may have variations in the cationic and anionic groups, these materials have not been suggested as oxygen scavengers, nor, in general, have they been found useful in food packaging applications. It is highly desirable to provide an effective oxygen scavenging material and system that has good oxygen absorption and capacity capabilities and that does not adversely affect the color, taste and odor of the packaged material. It is further desired to provide a material and system that is capable of inhibiting the release of by-products of oxidation that may adversely affect the color, taste or odor of the packaged material. Furthermore, it is desired to provide an effective oxygen scavenging system having an active scavenging agent contained within a carrier and the agent still provides effective scavenging capacity. It is further desired to provide an effective oxygen scavenger system that is thermally stable and, by this means, is capable of allowing the packaging system to be formed by traditional techniques including high temperature processing steps.

SUMMARY OF THE INVENTION The present invention is directed to an oxygen scavenger and the composition capable of providing good oxygen absorption capabilities while not adversely affecting the color, taste or odor of packaged material within a container having the composition as a part of it. The oxygen scavenger of the present is a modified anionic hydrotalcite particulate material. The present oxygen scavenging composition is formed of a polymer or similar carrier having the hydrotalcite particulate material impregnated therein. The oxygen scavenger system is capable of being activated by moisture. The present invention is further directed to a molded structure containing or derived from the present composition and to the containers that are formed with or contain the present composition.

DETAILED DESCRIPTION The present invention is directed to an oxygen scavenger composition formed of a carrier containing an effective oxygen scavenging amount of a modified, anionic hydrotalcite material distributed therein, as described in more detail below. The carrier can be a polymeric matrix in which the present particulate material is distributed substantially uniformly, or film or mat (woven or non-woven) having the particulate material present distributed substantially uniformly therein or deposited therein, or a permeable bag to the humidity that contains the particulate distributed in the same. The present invention further provides an improved container for packaging materials, such as food, beverages and the like, which are susceptible to oxidative degradation. The present improved container is capable of preserving the quality of the product and improving the shelf life of the packaged material without adversely affecting the color, taste or odor of the packaged material by the present oxygen scavenging composition. It also provides a packaging system that can have high levels of oxygen scavenging agent therein while complying with governmental regulation standards related to the quantities of such agents contained in food products. The anionic hydrotalcite type material which is an oxygen scavenger of the present invention has the general formula: [Aa ~ (x + y) / a • nH20] (x + y) - (very unreadable) wherein M represents magnesium (preferred), zinc, nickel, copper or cobalt or mixtures thereof in their valence state plus 2, M111 represents aluminum (preferred), chromium or iron or mixtures thereof in their valence state plus 3. In certain cases the HTLC of the present may further contain M cations which represents an alkali metal cation such as sodium (preferred), potassium or the like having a valence state plus 1. M may be present when "a" (as defined later) has a value of at least 2, in a molar quantity, and equal to a value from 0 to about 0.5. The ratio of M to M is from 1 to 5; OH represents hydroxyl groups; x has a numerical value from about 0.1 to 0.5; and n has a numerical value from 0 to 4 and, generally, from 1 to 4. The symbol A of the above formula represents, at least in part, an anion containing the oxygen scavenger group. This anion containing the oxygen scavenging group can be, for example, inorganic anions such as sulfite, bisulfite, dithionite and the like which are capable of reacting with oxygen or organic anions such as, for example, ascorbates, thiolates or phenolates and the like which are able to react with oxygen. The remainder of the anion A being residual anion of the HTLC precursor, as fully described below. The anion A must be at least 60 mol%, preferably at least about 80 mol% and preferably at least about 90 mol% in the form of the inorganic or organic oxygen scavengers previously described, the rest being residual anions of the original hydrotalcite and / or other anions. The symbol "a" of the above formula represents the numerical value of the valence of the anion A. For example, the value of "a" for a sulfite anion or dithionite is 2, while the value of "a" for the bisulfite, ascorbate or phenolate is 1. The value of "a" for the residual anion will depend on the identity of the anion and, in general, it will have a value of 1 to 3. In general, when the modified anionic hydrotalcite material has anions A that represent mainly monovalent anions, such as bisulfite, phenolate or ascorbate, as already described, or formed in a way that does not produce M, as part of the resulting product, the oxygen scavenger of the present invention can be represented by the formula general: [Mtlxl ±? _xM / GI1I ± IJ * x (OH) 2] i x x- ~ x- (illegible) where each symbol is the same as it was already defined. The term "ascorbate anion" as used in the present invention and in the accompanying clauses refers to the deprotonated species of ascorbic acid in its D or L form and any derivative or analogue thereof, including, for example, erythorbic acid and mixtures thereof. of the same. It is preferred that the ascorbate anion be selected from the deprotonated species of ascorbic acid D or L, or fatty acid derivatives of ascorbic acid as well as mixtures thereof. The term "phenolate anion" as used herein and in the appended clauses, refers to (i) aromatic ring compound containing deprotonated hydroxyl group or condensed aromatic ring. Examples of the phenolic compounds from which phenolate anion can be obtained include phenol, pyrocatechol, resorcinol, pyrogallol, pyrocatechol monoethyl ether, resorcinol monoethyl ether, hydroquinone, 1,2,4-trihydroxybenzene, tetrahydroquinone, 2-4. dibutylphenol and the like; or (ii) aromatic ring compounds containing hydroxyl group or fused aromatic ring further containing a deprotonated carboxylic acid group such as salicylate anion, 3-hydroxybenzoate, 4-hydroxybenzoate, 3,4,5-trihydroxybenzoate and the like. The term "hydrotalcite type" is a term recognized in the art (see Cavani et al., Catalyst Today 1_1 173 1991) and is used herein in a manner consistent with such use. Modified anionic hydrotalcite-type materials of the present may be formed by different means. In a case, the anionic HTLC having a labile anion can be used co or the precursor in the formation of the material herein. The anion of the anionic hydrotalcite precursor type material must be sufficiently labile to be easily exchanged with the oxygen scavenger anion. HTLC having lower alkanoic acid anions, such as C1-C5 monocarboxylic acid anion (eg, formic, acetic, propionic or butyric anions or the like) is a preferred anionic HTLC to be used as the precursor material. The formation of such a precursor material is described in U.S. Patent 5,399,329, the entire teachings of which are incorporated herein by reference. The oxygen scavenging agent present is formed by anion exchange of the above-described precursor material, in the absence of oxygen, with alkali metal or alkaline earth metal salts of an oxygen scavenger anion described hereinabove. Otherwise, the modified anionic hydrotalcite type material of the present can be formed by reacting, in the absence of oxygen, the salt or the conjugated acid (the protonated form) of at least one of the oxygen scavenging anions present with HTLC. having anions ^ carbonate. The reaction can be carried out in deoxygenated water as the reaction medium. The reaction product is washed with deoxygenated water in the absence of oxygen to produce an water-insoluble, oxygen-purifying active material of the present invention. Yet another way of producing the modified anionic hydrotalcite type material of the present uses the previously calcined hydrotalcite. The calcined hydrotalcite without associated anions can react with conjugated acids of the oxygen scavenging anions described above in the absence of oxygen to produce the materials herein. In the case of bisulfite or sulfite this can be achieved by using a solution of sulfur dioxide in water. In yet another method, a suitable source of trivalent metal (such as aluminum hydroxide) can react, in the absence of oxygen, with a suitable source of the divalent metal (such as magnesium oxide or nickel hydroxide) in the presence of acids conjugates of the oxygen scavenger anions described above to produce the materials herein. The oxygen scavenger of the present invention has been found to provide effective activity and oxygen scavenging rate when the agent is placed in the presence of oxygen and moisture. Thus, the HTLC currently described should be maintained in the absence of oxygen during formation and the absence of oxygen or moisture during storage. When the present agent is formulated in an oxygen scavenging composition with a carrier, such as a polymeric matrix, the carrier must be able to keep the agent substantially free of moisture to the extent necessary to initiate activity) [sic] A high rate of oxygen purification occurs to provide preservation of packaged, contemplated foods. The preferred oxygen scavenger of the present invention preferably has magnesium as M I. However, the magnesium may be partially (up to about 50 mol%) substituted from the cation family selected from nickel, cobalt, zinc, copper, manganese or mixtures thereof. In addition, the preferred agent has aluminum as M111. However, the aluminum can be partially (up to about 50 mol%) substituted from the family of cations selected from chromium, iron or mixtures thereof. The modified HTLC of the present has been unexpectedly found to provide a desirable means to provide a high degree of oxygen scavenging activity to the present composition and, by this means, provides better capacity and activity to purify oxygen while not allowing it to the initial oxygen scavenger material and / or some byproduct of the resulting oxidation migrates towards or adversely affects the color, taste or olox of the articles in contact with the present composition. It is considered, although not intended to be a limitation of the present invention, that the precursor HTLC has the ability to have the oxygen scavenging anions described above as part of the structure of the HTLC. Because the present oxygen scavenging HTLC has a plate-like structure with a small thickness of about 0.005 to 0.1 microns (usually 0.02 to 0.06 microns) and a width to thickness ratio of at least about 50 and generally in the range from 50 to 5000 and, usually from 50 to 1000, the main ion exchange occurs on the surface of the plate. This allows the oxygen scavenging anion to be able to react easily with oxygen in the presence of moisture to provide a desired oxygen scavenging agent. Furthermore, it is considered that the modified HTLC of the present reacts with any by-product of the oxidation (through the hydroxyl group) or the by-products of the oxidation that can be formed are adsorbed onto or absorbed within the crystal structure of the modified HTLC present. The present oxygen scavenger is formed by anion exchange to provide an HTLC containing the oxygen scavenger anion as already described. The anion A of the present agent must be at least about 60 mol% oxygen scavenging anion, preferably at least about 80 mol% and more preferably at least about 90 mol%. Minor molar percentages may be acceptable where the smaller amount still provides sufficient oxygen scavenging activity for a specific application. The exact percentage can easily be determined by one skilled in the art. However, the high degree of anionic sites located on the surface of the HTLC provides the ability to provide a high capacity oxygen scavenger. This capacity allows one to obtain prolonged storage capacity of the resulting packaged product. The amount of the oxygen scavenging agent will depend on the anticipated application of the resulting scavenging composition. When large amounts of the composition are used to purify small volumes of oxygen (as can be in can coating applications) the amount of the oxygen scavenging agent can be as low as about 0.5% by weight of the composition and, preferably, at least 1% by weight of the composition. In other traditional applications, such as lining caps and the like, where the charge of the particulate in the polymeric carrier is low and / or the amount of the composition is small, the amount of the oxygen scavenging agent must be at least about 2. % by weight, preferably from 2 to 20% by weight, more preferably from 4 to 15% by weight, based on the weight of the composition. The exact amount of the oxygen scavenging agent needed for a particular application can be easily determined by the artisan. The present invention provides a means to obtain a wide range of scrubbing agent content that includes high weight percentages. The modified HTLC agent described above is a finely divided solid which is particularly suitable for replacing some or all of the filler material commonly found in sealant compositions or films that are applications contemplated herein. The composition present as a whole is effectively anhydrous, that is, it provides a moisture content lower than that necessary to activate (initiate at a substantial rate) the purification of oxygen. Thus, it is preferred that the carrier component of the composition is a polymer matrix which is also preferably anhydrous. In general, the polymer matrix substantially protects the scrubber from moisture under normal atmospheric conditions and, therefore, the oxygen scavenging agent remains substantially inert to the purifying activity. However, once a high degree of humidity is achieved, as in a closed container environment for food products, the purification activity is initiated or activated. The humidity input of the polymeric matrix carrying the composition is traditionally accelerated by common practices such as hot filling, sterilization, pasteurization, autoclaving and the like. The polymeric matrix must be sufficiently permeable to allow moisture and oxygen to pass into the mass of the matrix and make contact with the particulate material. In one embodiment of the present invention, the carrier of the present composition consists of a polymeric matrix material, ie, the polymeric material which will form a solid matrix having therein distributed the modified hydrotalcite oxygen scavenging agent particulate material of the present. The polymeric matrix material will be selected considering the nature of the composition (dispersion, latex, plastisol, anhydrous mixtures, solution or melt) and its use as part of the container in a conventional manner. The polymeric matrix material is chosen from at least one polymeric material that can form a solid or semi-solid matrix. The polymer matrix material can be obtained from a variety of polymers that are available in a variety of bulk physical configurations such as dispersion, latex, plastisol, anhydrous mixture, solution or melt (for example, the thermoplastic polymer that can be melted) . The particular physical configuration of the selected polymer will depend on the final structure in which the present composition will ultimately be formed or incorporated. The polymeric matrix is obtained from the types of polymers that can be thermoplastic or thermostable. The primary functions served by the polymeric matrix for the purposes of the present invention are to provide a compatible carrier (a material that is stable under the normal temperature conditions of the packaging and does not deactivate the oxygen scavenging activity of the modified hydrotalcite agent herein) for the oxygen scavenger which is fully described herein above and allow the entry of oxygen and water into the composition and allow them to come into contact with the oxygen scavenger. The range of the polymer in general can be very broad. However, the polymer matrix can also be selected to perform additional functions depending on the physical configuration in which it is provided in a final structure in which it is formed or incorporated. Thus, the particular polymer or mixture of selected polymers will ultimately be determined by the end use in which it exerts its oxygen scavenging effect. Accordingly, suitable polymers from which the polymer matrix can be obtained include polyolefins, vinyl polymers, polyethers, polyesters, polyamides, phenol-formaldehyde condensation polymers, polysiloxanes, ionic polymers, polyurethanes, acrylics and polymers that occur naturally as cellulosics, tannins, polysaccharides and starches. Suitable materials for use as the component of the polymer matrix of latex compositions, for example, for ends of cans, are described in U.S. 4,360,120; U.S. 4,368,828 and EP 0182674. Suitable polymeric materials for use when the compositions are organic solutions or aqueous dispersions are described in U.S. 4,360,120; U.S. 4,368,828 and GB 2,084,601. Suitable materials for use in thermoplastic compositions include the materials proposed in U.S. 4,619,848; U.S. 4,529,740; U.S. 5,014,447; U.S. 4,698,469; GB 1,112,023; GB 1,112,024; GB 1,112,025 and EP 129309. The teachings of each of the references mentioned hereinbefore are incorporated by reference in their entireties. In particular, the polymeric material can generally be selected from polyolefins such as, for example, polyethylene, polypropylene, ethylene / propylene copolymers, ethylene / propylene modified with acid copolymers, polybutadiene, butyl rubber, styrene / butadiene rubber, styrene / carboxylated butadiene, polyisoprene, styrene / isoprene / styrene block copolymers, styrene / butadiene / styrene block copolymers, styrene / ethylene / butylene / styrene block copolymers, ethylene / vinyl acetate copolymers, ethylene copolymers / acrylate and ethylene / (meth) acrylate (for example, copolymers of ethylene / butyl acrylate or ethylene / butyl methacrylate), ethylene / vinyl alcohol copolymers, alternating copolymers of ethylene or propylene / carbon monoxide, homopolymers and copolymers of vinyl chloride, vinylidene dichloride polymers and copolymers, styrene / acrylic polymers, polyamides and ac polymers vinyl ethane and mixtures of one or more of these. Polyethylenes that have been found useful in the formation of the present composition include high density polyethylene (HDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), ultra low density polyethylene (ULDPE) and the like , as well as copolymers formed of ethylene with one or more other lower alkenes (e.g., octene) and the like. The compositions according to the invention can use a polymer matrix composed of thermoplastic polymer such as, for example, polyethylene or polyethylene copolymers such as ethylene / vinyl acetate and the like or mixtures of polyethylene such as mixtures of HDPE and butyl rubber.; polyethylene and ethylene / vinyl acetate copolymer; as well as polyethylene and styrene / butadiene / styrene block polymer and the like. The polyethylene, if used, is preferably a low density polyethylene, and can be a very low or ultra low density polyethylene that can be branched or linear. The ethylene / vinyl acetate copolymer, if used, preferably has a melt index in the range of 3 to 15, preferably 5 to 10, and generally contains 5 to 40%, preferably 5 to 30. % vinyl acetate. Particularly preferred compositions are a plastisol or a dry polymer mixture which can be used in combination with a plasticizer to form the polymer matrix. Suitable materials for use when the compositions are plastisols include homopolymers and copolymers of vinyl chloride. Instead of preparing these compositions as true plastisols, these can be provided as dry mixtures of the polymer and plasticizer. The proportion of the plasticizer present in the vinyl resin plastisol can be any conventional proportion, usually from 30 to 150 parts by weight of the plasticizer per 100 parts by weight of the vinyl resin. The polymeric carrier can be formed of different thermosetting resins such as polyurethanes, phenolics, epoxy-ester resins, epoxy resins, polyesters and alkyds. These resins are usually formed in solutions or suspensions with organic liquids and applied to the internal surface of a vessel followed by the application of elevated temperature to remove the liquid and cause solidification (for example, by crosslinking) of the resin coating on the substratum. The polymer matrix of the composition can also contain conventional plasticizers, which includes phthalates, adipates, glycols, citrates and epoxidized oils and the like. Examples include, for example, dioctyl phthalate, diisoctyl phthalate or diisodecyl phthalate, which are commercially available. Other useful plasticizers are butyl benzyl phthalate, acetyl tributyl citrate, ethyl diphenyl phosphate and diisobutyl phthalate. A particularly useful combination of plasticizers for use with a vinyl chloride / vinyl acetate copolymer resin is a mixture of diisodecyl phthalate and diisoctyl phthalate in a weight ratio of about 7-8: 1. A preferred aspect of the invention is that the oxygen scavenger must remain substantially inert in the composition and in the joint or other solid deposit formed with the composition present until the composition is on or in the sealed container. Exposure of the composition to high humidity that normally exists within a sealed container, therefore, will give rise to sufficient moisture permeation into the composition and will cause the oxygen scavenger present to initiate a satisfactory degree of purification. This will result in better storage life of the packaged material. In addition, the depuration reaction can be accelerated by heating the composition sufficiently while it is in the closed container to cause increased moisture permeation. Thus, the oxygen scavenger preferably will remain substantially inert in the carrier until the scavenging reaction is accelerated by heating in the presence of moisture. Where the oxygen scavenging agent present has a sufficient amount of water molecules associated therewith to provide the moisture required to cause oxygen scavenging, it is preferred that the compositions having such hydrated particulate material be stored under an inert atmosphere until it is they use. Preferably, the purification reaction of the present composition is accelerated by pasteurizing (usually at 50 ° -100 ° C) or by sterilizing (typically at 100 ° -150 ° C) the container after filling with an aqueous fill and the sealed. This activation appears to be a consequence of the present composition, when heated, allowing moisture to permeate into the composition and make contact with the oxygen scavenging agent present. The moisture becomes trapped in the composition, thereby bringing the scrubbing agent into contact with sufficient water to allow reaction with the oxygen present. This oxygen can permeate through the composition from the oxygen trapped inside the container when it was filled or which subsequently enters the container from the surrounding atmosphere. Although some traditional oxygen scavengers degrade when subjected to elevated temperatures, the oxygen scavenger of the present has been found stable at the elevated temperatures commonly experienced in the processing of polymers in films or coatings, the removal of solvents. of plastisol compositions, pasteurization, sterilization and similar processes commonly carried out in packaging technology. The polymeric matrix of the compositions herein may also contain inert filler materials, slip aids, process aids, pigments, stabilizers, antioxidants, thickener resins, foaming agents and other conventional additives in common amounts, depending on the nature of the composition and its final use. If the polymer matrix is part of a thermoplastic composition, the total amount of these additives is generally below 10%, more preferably below 3%, based on the total weight of the composition. However, when the composition is a plastisol, dispersion, organic solution or latex, the amounts of additives based on the polymeric material may be higher. If an antioxidant is incorporated, this must be present in amounts capable of stabilizing the polymer composition against degradation of life to the free radicals formed during processing. However, the amount of antioxidant must be small enough to allow the oxygen scavenger present in the composition to react effectively with molecular oxygen. The specific amount will depend on the antioxidant used and can be determined with minor experimentation. The composition of the invention can be formulated in any traditional manner, such as a melt, plastisol, organic solution, dry mix, latex or dispersion. The main ingredients of the composition, in addition to the oxygen scavenging agent, are usually common to the traditional entities present for the proposed purpose. It is preferred that the total composition should be non-aqueous (ie, an anhydrous solution, plastisol or thermoplastic melt) to prevent initiation of the scrubber reaction within the composition. Otherwise, the scrubber may be encapsulated in a carrier sufficient to prevent it from coming into contact with water and / or oxygen until it is within the closed environment of the container. The polymeric matrix carrier of the composition herein may be selected from those used to form coatings on at least a portion of the inner surface of a package (e.g., a rigid package such as a can, a can lid, box , cardboard or similar). The polymer matrix can be selected from the classes of polymers commonly known as epoxies, phenolic (for example, the polymer of phenol-formhyde condensation), lacquers (for example, esters or ethers of cellulose, shellac, alkyd resins [sic] and similar), polyurethanes and others. The carrier matrix can be mixed with the above-described oxygen scavenging agent to provide an encapsulated particulate which can subsequently be used in a second polymeric matrix or applied on (as can be solvent application or melting) the surface of a second carrier material. The composition herein can also be used to form a film carrying the oxygen scavenging agent present. The carrier can be formed from a polymeric material such as those described above, capable of forming a film and deposited on the surface thereof the oxygen scavenger present. The film may be composed of a single layer or a plurality of layers. The surface of the film can be coated with the oxygen scavenging agent present by forming a suspension or dispersion of the particulate in a polymer and depositing the suspension or dispersion by a conventional means, such as by spraying or applying the coating with a knife or the like, directly on the surface of the carrier film. The specific nature of the carrier film will depend on the contemplated application and the capacity of the carrier formed to have the oxygen scavenger adhered to its surface and substantially retain its integrity during use. The carrier may, otherwise, be in the form of a fibrous mat (woven or non-woven). The composition of the oxygen scavenger present is contained in the interstices of the structure of the mat. The fibers forming the mat can be formed of any suitable material or synthetic fiber such as cotton, glass, nylon, polyethylene and copolymers of ethylene with one or more ethylenically unsaturated monomers, polypropylene and copolymers of propylene with one or more ethylenically unsaturated monomers and the like . The specific nature of the carrier mat will depend on the application of its use and the ability of the mat to preserve the oxygen scavenging material within the interstices of the mat structure during use. The scrubber can be deposited in the structure of the mat by any means such as by 'immersing the mat in a dispersion or suspension of the scrubber and then removing the liquid from the mat or first forming particulates of the scrubber / polymer composition which is deposited molten on and in the mat structure. In another embodiment, the present oxygen scavenging composition can be retained within a carrier in the form of a sack or sachet of suitable size to be inserted into a container having an oxygen sensitive material therein. The bag or sachet should be sufficiently porous to allow moisture and oxygen to penetrate through the material that forms the bag or sachet under ambient temperature conditions. The oxygen scavenging composition present in this way is composed of a sac or sachet carrier having therein the oxygen scavenger, per se, or contained in a polymeric matrix and provided in the form of small particles of sufficient particle size to allow the structure of the sachet to keep the particulate in it. The sachet can be formed of natural or synthetic materials such as paper, cotton, cloth, polymeric films or the like, in forms well known in packaging technology. A fourth embodiment is to use a carrier in the form of a porous inorganic material, such as a ceramic having the oxygen scavenger agent distributed therein. The ceramic can be formed into any desired shape (e.g., spheres, cubes, cylinders and the like) and size that is suitable for insertion into the container having the oxygen sensitive material. Useful porous inorganic materials include conventional clay, cement pastes and the like. It has been found that the oxygen treatment compositions described above can be used for the preservation of oxygen sensitive foods stored under ambient conditions. The compositions herein have an advantage over compositions having oxygen scavengers directly mixed in and forming a filler of a polymer matrix because the present compositions inhibit the release of the scavenging agent and / or oxidation byproducts that can contaminate the food material. The oxygen scavenger of the present invention is a particulate material which contains, as part of its structure, an oxygen scavenging portion that can be activated by moisture. It has been found that the nature of the system is such that the oxygen scavenger is highly reactive with molecular oxygen but binds to the hydrotalcite in a form that substantially prevents the migration of the oxygen scavenging portion or its oxidized products to the packaged material. . Thus, the present invention unexpectedly provides a highly desired oxygen scavenging composition that does not cause discoloration or damage the taste of the packaged food product. It may be desirable to include in the composition, especially when used as a gasket or the like, a material that increases the permeability of the composition to water, for example, a surfactant such as sodium dodecylbenzene sulfonate or other hydrophilic compounds. A suitable amount of a surfactant is between 0.1 and 1.0% by weight. The amount of the particulate containing the oxygen scavenging agent present depends on the type of application. When the particulate is incorporated in a joint, the amount is usually at least 0.5% by weight based on the material of the polymeric matrix, generally at least 1% and preferably at least 2%. Generally it is not necessary that the amount is above 20% and 4% -10% is usually a convenient maximum. In the case of a plastisol, lacquer or hot melt applied to the central panel of a closure, where the matrix does not serve as a joint, the charges of the particulate scrubber may be much greater. For example, loads of 20% by weight to 60%, or in some cases up to 90% are functional. When the composition is in the form of a film, mat, sachet or sachet, the oxygen scavenger must be present in an amount to effectively purify the oxygen during the contemplated storage period of the container for suitable contents. An amount in the range from 0.01 to 2 grams of the oxygen scavenger having at least about 60 mol% of the oxygen scavenger anion A is normally sufficient to provide desired oxygen scavenging capacity in a normal-sized container (50-1000 ml). ). The present composition can be used as part of a packaging container that can provide storage stability to the material packaged therein without deteriorating the flavor, odor or taste of the material. The present composition must be exposed to the interior atmosphere of the resulting sealed container in any form as it may be as a coating on all or a portion of the interior surface of the container body or closure means (eg, the lid, the end of the can) or as an insert in the form of a film, mat, bag, sachet or ceramic structure. The composition of the invention in the form of a film can, for example, be laminated to the cardboard to form inverted V-shaped cartons. The film may also contain oxygen barrier layers and / or heat sealable layers. The invention formed with a polymeric matrix in the form of a film can be applied as a coating on the central panel in a container closure. The closure can be a lid, end cap, raw material for lid or film. The invention also includes container closures carrying a solid deposit forming on the closure from a polymeric matrix or film composition and which is placed to seal around or over a line of weakness in the closure. The solid deposit may be a seal deposited around the closure and formed of the composition. Instead of, or in addition to the reservoir being like a gasket, the composition can be deposited on the inner side of a closure in a position where there is a discontinuity or line of weakness around a component to push or pull to open a sealed container by the closing. The closure occupies, as is traditional, only a minor part of the exposed surface area of the closed container, usually less than 25% of the surface area. Thus, the area of the solid deposit can be very small relative to the area of the container. Despite this, the invention can provide much better storage stability for the contents. The invention also includes filled containers, sealed with these closures. The sealed container comprises a container body, the closure fitted thereon and the packaged material that is contained within the container body. The container body is preferably made of glass or metal. The preferred closure is metal. The packaged material can be any beverage, food product or other material to be stored inside the container, but the invention is of particular value when the filling is a material whose shelf life or product quality is normally limited by the oxygen entering or contamination during storage. The body of the container may be a can, generally made of metal, in which case the closure is one end of the can. Generally the complete closure is made of metal or polymeric material, but the closure panel may include a removable component of metal or polymeric material. Instead of a can body, the body of the container can be a bottle or jar in which case the closure is a lid. The bottle or jar is preferably made of glass but can be made of polymeric material with very low oxygen permeability. The lid can be made of polymeric material, for example a polypropylene, which may include a barrier layer. In general, the lid is formed of metal and may include a push or pull component of metal or polymeric material. The cover can be a crown cap, such as a forced crown with a lever or a torsional break, a torsionally mounted cap, a lid, a pressure / twist break or a pressure / forced lever cover, a cover threaded, metal lid with movable ball, continuous screw cap or any other traditional form of metal lid or polymer lid suitable for closing the bottle or jar. A gasket is normally provided between the container body and the closure. This joint can be used to carry the composition of the invention (in particular, as a polymer matrix containing the composition) as a mixture in the joint composition or as a separate component applied on or near the joint but it is possible that the The composition of the invention is used anywhere on the closure or anywhere in the container. In this case, the composition that forms the joint can be any suitable unaltered traditional composition to form the joint. When the closure is a lid, the present cleaning composition can form a total joint or a portion of a total joint. This is usually true for small diameter caps such as those smaller than 50 mm in diameter. For large diameter lid caps, the gasket is a ring-type gasket and can be deposited in a traditional way from the gasket forming composition. For example, the ring-type joint can be formed on a lid by being applied in liquid form as a ring and can then be converted to the solid form by drying, heating to cure or cooling to harden a thermoplastic, as appropriate. The oxygen scavenging composition can be mixed into the gasket material, deposited on the gasket material or applied to an area of the gasket not covered by the gasket (the center panel). The joint forming composition can, for this purpose, be a dispersion, latex, plastisol, dry mix, suitable thermoplastic composition or organic solution. The lid, carrying the joint, is then compressed on a suitable sealing face around the open end of the container body filled and closed in the conventional manner. If the composition is formed with a thermoplastic polymer matrix, it can be applied as a low viscosity melt while the cap is rotating, to deposit the composition in the shape of a ring, or it can be applied as a melt which is then molded into the desired shape, often as a disk having a thickened ring-like portion. In addition, the gasket may be in the form of a preformed ring or disk that is retained (e.g., by mechanical or adhesive means) within the lid. If the closure is a can end, the oxygen scavenging composition is usually not used in the joint composition because, under normal conditions for can stance, the joint is not substantially exposed to oxygen in the container. the packaging. Also, seams are not particularly vulnerable to oxygen ingress. The oxygen scavenging composition is commonly applied to a central panel or other interior surface in the can, as it can be applied as a coating of a can. It is particularly preferred that the gasket or liner on the container closure is formed by applying a fluid or molten composition of the present invention formed within a fluid polymer matrix and solidifying it on the closure. The method of application and solidification is generally traditional. It is particularly preferred that the container and can end be made of metal or the body of the container should be glass and the closure of metal or plastic, since the use of the compositions defined to form the joint then appear to give particular beneficial results . In particular, excellent results are obtained when the body of the container is a glass bottle and the closure is a metal lid. Instead of, or in addition to using the composition of the invention in the fluid or meltable polymer matrix to form a joint, it is possible to deposit the composition anywhere on the internal face of the closure. This can be applied as a total covering of the internal face of the closure panel or it can be applied on only a part of the internal face. In particular, when the panel includes one or more push or pull components defined in the panel by discontinuities or lines of weakness, the composition may be applied primarily to cover only the discontinuity or line of weakness. For example a type of closure, usually a can end, includes at least one, and often two thrust components that are defined by partial registration lines through the metal panel so that the pressure of the finger can push a circular area of the panel towards the container, to allow access to the contents of the container. Thus, there may be a small thrust component to allow release of pressure and a larger thrust component to allow the liquid to be emptied from the container. This system is described in, for example, DE 3,639,426. In particular, the composition of the first embodiment of the present invention can be deposited as a ring (or a disk) covering the weakening line. The weakening line can simply be a weakened line in the metal panel, but it can be a total cut around the push component, for example, as in DE 3,639,426, in which case the push component generally has a slightly larger area than the hole in the panel that is defined by the cutting line and the composition of the invention can then form a seal between the pushing component and the rest of the closure panel. In all cases where the push or pull components are to be formed within the metal panel, there is a serious risk that the formation of the push or pull components may damage the coating of the polymer lacquer that is generally present on the surface internal of the metallic panel. This can expose the metal to corrosion. The application of a composition of the present invention to a container as described herein can inhibit the corrosion of the metal container as well as improve the storage stability of the contents of the container, especially water-bearing contents, such as beer. In addition to use in metal, glass and plastic containers, the compositions may be used in a cardboard or laminate container such as a juice box. This container is a cardboard or tube with an internal lining. The composition can be applied in or laminated to the inner lining of the carton, along a line of weakening in the closure of the package, or in any other convenient place in the package. Otherwise, the present composition can be placed inside the container as a film, mat or sachet.

In addition, the composition of the present invention can be compounded and extruded, injection molded or thermoformed into the desired shapes when the polymer matrix is a thermoplastic resin. For example, the present compositions can be formed into films per se or as a component of a film composition used to prepare a flexible package, such as bags, or the films can be laminated into metallic materials that can then be formed into cans. and closures. Also, the compositions can be included in flexible packaging such as multilayer or laminated films or as a ribbon, bag, label or coating on a thermoplastic bag or cap material. When the present composition is part of a multilayer film, the layer formed of the present composition can be the surface layer that will be exposed to the inner surface of the resulting flexible package or an inner layer that is covered by a surface layer having sufficient permeability to allow that the O2 and moisture penetrate into and make contact with the layer that contains the present composition. Thus, the term "exposed to the interior", as used herein and in the appended claims, should mean direct or indirect exposure of the present composition to the internal atmosphere of a sealed container having packaged product contained therein. The compositions can also be used together with or as a portion of a membrane against rape for pharmaceutical and food products. The following examples are provided for illustrative purposes only and are not to be construed as limiting the teachings herein or the clauses appended thereto. All parts and percentages are by weight unless stated otherwise. In some cases, the particulate hydrotalcite oxygen scavenger, per se, was tested while in other cases the material was part of a polymeric carrier composition as described more fully below. To test the oxygen scavenging capacity, each sample was tested in triplicate by being placed in a vacuum sealed container, impermeable to the gas adapted with a septum to allow gas entry, and the gas samples were removed during periodic analyzes. The containers having a sample were injected with 100 common of the ambient air (ca. 20.6% of O2) and pasteurized at 60 ° C for 45 minutes and then stored in the dark to avoid photo oxidation. The oxygen concentration in the upper space was measured at regular intervals with withdrawn samples which were then analyzed using a MOCON® oxygen analyzer model HS-750 Headspace Oxygen Analyzer. All samples were prepared and tested in triplicate and the data were averaged to obtain the reported values.

Example I Preparation of hydrotalcite with functional bisulfite Under a nitrogen atmosphere, 90 parts of sodium bisulfite were dissolved in 510 parts of deionized water which had previously been purged of oxygen with nitrogen. To this solution were added 100 parts of uncalcined HTLC acetate, having a sheet type morphology and the formula [Mg75Al.25 (OH) 2] (02CCH3) .25 »xH20 (obtained from LaRoche Industries Inc.) The slurry was stirred for one hour under nitrogen and then the solids were collected by vacuum filtration under a nitrogen atmosphere. The material was taken in 600 parts of deionized water purged with nitrogen and stirred for one hour. The solids were again collected by vacuum filtration and washed with 6000 parts of water purged with nitrogen. The material was dried for nine hours at 80 ° C in a vacuum oven to produce approximately 60 parts of a white fine powder.

Example II Alternative preparation of functional bisulfite hydrotalcite Under a nitrogen atmosphere, 22.5 parts of sodium bisulfite were dissolved in 127.5 parts of deionized water that had previously been purged of oxygen with nitrogen. To that solution were added 25 parts of a functional carbonate hydrotalcite, not calcined with a ratio. Mg / Al of approximately 2.4 ([Mg.7Al.3 (0H) 2] (C0.3) .i5 * xH20), (from Alcoa, HTC-24). The slurry was stirred for one hour under nitrogen. The solids were then collected by vacuum filtration under a nitrogen atmosphere and washed with 150 parts of water purged with nitrogen, deoxygenated. The solids were then taken in 150 parts of deoxygenated water, purged with nitrogen and stirred for one hour before filtering again and washing with 2000 parts of deoxygenated water, purged with nitrogen. The product was dried in a vacuum oven at 80 ° C for 6 hours.

Example III Alternative preparation of functional bisulfite hydrotalcite Under a nitrogen atmosphere, 45 parts of sodium bisulfite were dissolved in 255 parts of deionized water that had previously been purged with argon. To that solution were added 20 parts of a hydrotalcite carbonate functional, not calcined with an Mg / Al ratio of 1.0 ([Mg5Al.5 (0H) 2] (C03) .25"xH20), (from Alcoa, HTC-10L). The slurry was stirred for one hour under argon with heating at about 60 ° C. The solids were then collected by vacuum filtration under an argon atmosphere and washed with 600 parts of deoxygenated water, purged with nitrogen. The solids were then taken in 300 parts of water purged with argon and stirred for one hour before again filtering and washing with 1500 parts of water purged with nitrogen. The product was dried in a vacuum oven at 80 ° C for 6 hours to produce a fine white powder.

EXAMPLE IV Alternative Preparation of Functional Hydrotalcite Bisulfite To a reaction vessel fitted with a condenser and flushed with argon were introduced 320 parts of deionized water purged with nitrogen. 53 parts of sulfurous acid (approximately 6% of SO2 in water) were introduced and the resulting solution heated to 60 ° C with stirring under an argon atmosphere. 10 parts of hydrotalcite (HTC-24 from Alcoa) that were calcined at 450 ° C for one hour were also introduced under positive argon pressure. The resulting slurry was heated at about 90 ° C for 6 hours, then allowed to cool to room temperature. The solids were collected by vacuum filtration under nitrogen atmosphere. The product was dried in a vacuum oven at 80 ° C for 4 hours to produce a fine white powder.

EXAMPLE V Preparation of Functional Hydrotalcite Dithionite Under a glove compartment [sic] with nitrogen atmosphere, 22.5 parts of sodium hydrosulfite were dissolved in 127.5 parts of deionized water which had previously been deoxygenated being purged with argon. To this solution were added 10 parts of uncalcined hydrotalcite described in Example I above. The slurry was stirred for one hour under argon, and then the solids collected by vacuum filtration under a nitrogen atmosphere, and then washed with 300 parts of deoxygenated water, purged with nitrogen. The solids were again collected by vacuum filtration and washed with 1500 parts of water purged with nitrogen. The material was dried for 4 hours at room temperature in a vacuum oven to produce a fine white powder.

Example VI Preparation of hydrotalcite gallate functional 2.35 parts of sodium hydroxide were dissolved in 150 parts of deionized water and the resulting solution was purged with nitrogen. Under a nitrogen atmosphere, 10 parts of 3, 4, 5-trihydroxybenzoic acid (gallic acid) were added to the solution and stirred to form an amber colored solution. 10 parts of the uncalcined hydrotalcite described in Example I above were added to this solution and the slurry was stirred under a nitrogen atmosphere for one hour. The solids were collected under nitrogen through vacuum filtration and washed with 150 parts of deionized water purged with nitrogen. The solids were taken in 150 parts of deionized water purged with nitrogen and stirred for an additional hour. The solids were again collected by vacuum filtration and rinsed with 2000 parts of deionized water purged with nitrogen, at which time the filtrate ran clear. The material was dried for 6 hours at 80 ° C followed by 3 hours 150 ° C in a vacuum oven to produce 5.6 parts of a fine, amber-colored powder.

Example VII Preparation of functional ascorbate hydrotalcite Under a nitrogen atmosphere, 45.0 parts of sodium ascorbate were dissolved in 105 parts of deionized water which had previously been purged with nitrogen. To this solution were added 20 parts of hydrotalcite without calcining described in Example I above. The slurry was stirred for one hour under nitrogen, then the solids were collected by vacuum filtration under a nitrogen atmosphere. The material was taken in 150 parts of deionized water purged with nitrogen and stirred for one hour. The solids were again collected by vacuum filtration under nitrogen atmosphere and washed with 1500 parts of water purged with nitrogen. The material was dried for 6 hours at 80 ° C in a vacuum oven to produce a fine whitish powder.

Example VIII Preparation of Functional Hydrotalcite Cysteinate 13.2 parts of sodium hydroxide were dissolved in 400 parts of deionized water and the resulting solution was purged with argon. Under a nitrogen atmosphere, 40 parts of L-cysteine were added to the solution and stirred to form a colorless solution of sodium cysteinate. 20 parts of uncalcined hydrotalcite described in Example I above were added to this solution and the slurry stirred under argon atmosphere for one hour. The solids were collected under nitrogen atmosphere through vacuum filtration and rinsed with 600 parts of deionized water purged with nitrogen. The solids were taken in 400 parts of deionized water purged with argon and stirred for an additional hour. The solids were again collected by vacuum filtration and rinsed with 2000 parts of deionized water purged with nitrogen. The material was dried for 8 hours at 80 ° C in a vacuum oven to produce 13.4 parts of a fine whitish powder.

Example IX Preparation of hydrotalcite functional cystinate 6.7 parts of sodium hydroxide were dissolved in 400 .deionized water parts and the resulting solution purged with argon. Under the argon atmosphere, 20 parts of L-cystine were added to the solution and stirred to form a colorless solution. 20 parts of uncalcined hydrotalcite described in Example I above were added to this solution and the slurry stirred under argon for one hour. The solids were collected by vacuum filtration and washed with 600 parts of deionized water purged with nitrogen. The solids were taken in 400 parts of deionized water purged with argon and stirred for an additional hour. The solids were again collected by vacuum filtration and wiped with 2000 parts of deionized water purged with nitrogen. The material was dried for 6 hours at 80 ° C in a vacuum oven to produce 16.5 parts of a fine whitish powder.

EXAMPLE X Moisture-activated oxygen purification test method 1 gram samples of the hydrotalcite-exchanged materials in the anion formed in the above Examples I-IX were placed in gas-impermeable sacks, adapted with septum and vacuum sealed. For comparative purposes, the sodium salt of bisulfite, ascorbate and gallate were also tested by placing them in gas impermeable bags of the same type. Through the septum, 1 gram of water and 100 ce of air were introduced. The oxygen content of each bag was measured at regular intervals by removing 3 cc samples from the atmosphere inside the bags by means of a gas syringe and injecting them into a MOCON® analyzer model HS750 Headspace 02. The samples were measured in triplicate. Samples without added water were also monitored to test stability in the absence of water. In all cases, the samples without water showed no significant purifying activity. The results are shown in the following Table 1: TABLE I 1 mg of CuCl2 dissolved in lg of H20 added to the bag.

Example XI The storage stability and thermal stability of the hydrotalcite bisulfite functional type material was tested as follows. A quantity of the material was exposed to indoor ambient air for 90 days and then tested using the method described above of Example X. No significant decrease in activity was observed. A quantity of the material was placed in a preheated oven at 215 ° C for 12 minutes in air and then tested using the method described above of Example X. No significant decrease in activity was observed. The storage stability and thermal stability of the functional bisulfite hydrotalcite were also tested as follows: A quantity of the material was exposed to ambient indoor air for 90 days and then tested using the method described above; no significant decrease in activity was observed. A quantity of the material was placed in a preheated oven at 215 ° C for 12 minutes in air and then tested using the method described above: no significant decrease in activity was observed.

Example XII Closing compositions composed of polyvinyl chloride containing hydrotalcite-exchanged type material with bisulfite as formed in Example I above were exposed to water and low oxygen concentrations to mimic conditions within a package of food or beverage packaged under nitrogen. After 10 days, the water was analyzed for sulphite and sulphate (product of oxidation). For comparative purposes, sodium sulfite and sodium bisulfite were also tested and tested in the same way. a) PVC Plastisol: The scrubbing materials in the concentrations indicated in the following table were stirred in a PVC plastisol closure composition. Sodium sulfite and sodium bisulfite were first crushed in a mortar and pestle to provide finer particles with larger surface areas. The plastisols were then poured into circular molds and melted at 215 ° C for 3 minutes to form discs weighing approximately 2 g. b) Dry mix of PVC: The purifying material was mixed in a composition for closing dry mix of PVC by vigorous agitation. The powder mixture was then formed into sheets on a hot press at 300 ° F. Discs with an approximate weight of 330 mg were formed.

The discs were placed in gas-impermeable bags (one disc per bag for plastisol compounds, six discs per bag for dry mix compounds) fitted with a septum and heat-sealed in vacuum. 2 grams of ultra pure water and 100 ce of a mixture of approximately 1% oxygen / 99% nitrogen were then introduced through the septum. The sacks were then pasteurized at 60 ° C for 45 minutes. The samples were then prepared in triplicate. After 10 days, the liquid contents were extracted and fixed with 5% aqueous formaldehyde so that the sulphite / bisulfite will no longer oxidize. The samples were then analyzed by ion chromatography for sulphite and sulfate content. The results are shown in the following table: This series included an uncommon low value of 20 ppm associated with a correspondingly high measurement of sulfate. Out of range Limit of detection (LD) 3 ppm.

It is very evident that samples of the bisulphite-modified hydrotalcite type material showed no detectable sulfite migration, while both sodium sulfite and sodium bisulfite samples showed levels that were significant fractions of the theoretical maximum. In the same way, the hydrotalcite samples exhibited very low levels of sulfate migration compared to the controls.

Claims (28)

1. A hydrotalcite type material represented by the formula: [M: i? -? M? R? X (OH: 2 l x + M \ [Aa ~ (x + y) / a - nH20] (x + y) - (very unreadable) wherein M 1 represents an alkali metal; MII represents magnesium, zinc, nickel, copper or cobalt or mixtures thereof III themselves; M represents aluminum, chromium, iron and mixtures thereof; A represents an anion, at least 60 mole% of the anion compound oxygen scavenger; x is a numerical value from about 0.1 to 0.5; a is an average numerical value of the valence of A; and represents 0 when "a" is less than 2 and a value from 0 to 0.5 when when merios 2; and n is a numerical value from 0 to 4

2. The product of claim 1, wherein M, "n1 *" 1 * is at least 50 mol% Mg and M is at least 50 mol% Al.

3. The product of claim 1, wherein the oxygen scavenger anion A is selected from sulfite, bisulfite, dithionite, ascorbate, thioylate [sic], phenolate or mixtures thereof.

4. The product of claim 2, wherein the oxygen scavenger anion A is selected from sulfite, bisulfite, dithionite, ascorbate, thiolate, phenolate or mixtures thereof.

The product of claim 2, wherein the oxygen scavenger anion A is selected from sulfite, bisulfite, dithionite or mixtures thereof.

6. The product of claim 4, wherein the oxygen scavenger anion A is selected from sulfite, bisulfite, dithionite or mixtures thereof.

The product of claim 3, wherein the oxygen scavenger anion A is selected from ascorbate anion, thiolate anion, phenolate anion or mixtures thereof.

The product of claim 4, wherein the oxygen scavenger anion A is selected from ascorbate anion, thiolate anion, phenolate anion or mixtures thereof.

9. The product of claim 5, wherein the oxygen scavenger anion A is bisulfite.

10. The product of claim 6, wherein the oxygen scavenger anion A is bisulfite.

11. The product of claim 7, wherein the oxygen scavenger anion A is ascorbate anion.

12. The product of claim 8, wherein the oxygen scavenger anion A is ascorbate anion.

13. A composition containing a carrier having the oxygen scavenger hydrotalcite particulate of the claims 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12 evenly distributed therein.

The composition of claim 13, wherein the carrier comprises a polymeric matrix having at least 0.5% by weight of the hydrotalcite type oxygen scavenger material distributed therein.

The composition of claim 14, wherein the carrier is a thermoplastic resin selected from the group consisting of: polyethylene, ethylene / vinyl acetate copolymers, vinyl chloride homopolymers, vinyl chloride copolymers and mixtures thereof .

The composition of claim 14, wherein the carrier is a polymeric matrix consisting of a polyethylene selected from the group consisting of high density, low, very low, ultra low density and low density linear polyethylenes, mixtures thereof and mixtures of polyethylene with other polymers.

17. The composition of claim 14, wherein the carrier is a polymer matrix comprising a mixture of at least one polyethylene and at least one ethylene / vinyl acetate copolymer.

The composition of claim 14, wherein the carrier is a polymer matrix comprising a polymer selected from the group consisting of polyolefin, ethylene / vinyl acetate copolymer, butyl rubber, styrene / butadiene rubber, styrene block copolymers / butadiene / styrene, isoprene, styrene / isoprene / styrene block copolymers, styrene / ethylene / butylene / styrene block copolymers and mixtures thereof.

The composition of claim 14, wherein the carrier is a polymer matrix comprising one or more vinyl chloride resins.

20. The composition of claim 14, wherein the carrier is a polymeric matrix comprising an epoxide, phenolic, polyurethane, polyvinyl chloride homopolymer, polyvinyl chloride copolymers and mixtures thereof.

21. A product that is a container having an interior cavity suitable for containing an oxygen sensitive material, which has, as at least part of the container and exposed to the interior of the container, the composition of claim 13.

22. A product that is a container having a suitable interior cavity for containing an oxygen sensitive material, which has, as at least part of the container and exposed to the interior of the container, the composition of claim 14.

23. A product that is a container having an interior cavity suitable for containing an oxygen sensitive material, which has, as at least part of the container and exposed to the interior of the container, the composition of claim 15.

24. A product that is a container having a suitable interior cavity for containing an oxygen-sensitive material, which has, as at least part of the container and exposed to the interior of the container, the composition of claim 16.

25. A product that is a container having an interior cavity suitable for containing an oxygen sensitive material, which has, as at least part of the container and exposed to the interior of the container, the composition of claim 17.

26. A product that is a container having a suitable interior cavity for containing a material sensitive to oxygen, which has, as at least part of the container and exposed to the interior of the container, the comp of claim 18.

27. A product that is a container having an interior cavity suitable for containing an oxygen sensitive material, which has, as at least part of the container and exposed to the interior of the container, the composition of claim 19 .

28. A product that is a container having an interior cavity suitable for containing an oxygen sensitive material, which has, as at least part of the container and exposed to the interior of the container, the composition of claim 20.