Active oxygen scavenger compositions and their use in packaging articles

IS 2 178 176 T3

DESCRIPTION

Active oxygen captured compositions and their use in packaging articles.

This application is a continuation, in part, of the US application filed September 23, 1996, Serial Number 08 / 717,370. It is also a continuation in part of the PTC application filed on September 22, 1997, with Application Number PCT / US97 / 16712 and a continuation in part of the PTC application filed on February 17, 1998, with Application Number PCT / US98 / 02991.

Statement Regarding Federally Funded Research (Not Applicable)

Field of the invention

The invention generally relates to compositions with active oxygen scavenging capacity and the use of these compositions to improve the packaging of oxygen sensitive substances. Formulations that can be used in the manufacture of packaging articles or used as liners / liners containers are described.

Background of the invention

Plastic materials have continued to make significant advances within the packaging industry, due to the flexible design of their material and their ability to be manufactured in various sizes and shapes, commonly used in the packaging industry. The deployment of plastic materials in packaging articles such as films, trays, bottles, cups, bowls, liners and liners is now very common in the packaging industry. Although plastic materials offer the packaging industry many benefits with an unlimited degree of flexibility in design, the utility of plastic materials has remained inhibited in situations where the barrier properties of atmospheric gases (mainly oxygen) are necessary to ensure a long life. of the appropriate product. When compared to traditional packaging materials such as glass, steel or aluminum, plastics offer inferior barrier properties that limit their acceptability for use in packaging items that are sensitive to atmospheric gases, particularly when exposed to atmospheric gases. involve extended periods of time. The packaging industry continued to search for packaging materials that offer the flexibility of plastic design while having the barrier properties of glass, steel or aluminum.

It should be recognized that there are two broad types of barriers to protect oxygen-sensitive packaged substances from oxygen (usually air oxygen). One is known as a passive oxygen barrier and its utility is found due to superior resistance to oxygen permeability through such constructions. Glass and metal are essentially perfect passive oxygen barriers. Polymer condensation, particularly polyesters such as polyethylene terephthalate (PET) have found great acceptance in the packaging industry and are moderately good passive oxygen barriers. Polyamides, such as polyhexamethylene adipamide and polyphthalamides, are generally better passive oxygen barriers than polyethers when deployed in similar constructions.

The other type of oxygen barrier is known as an active oxygen barrier. An active oxygen barrier is a substance capable of intercepting and capturing oxygen (undergoing a chemical reaction with oxygen), for example, by attempting to permeate oxygen through packaging. An outstanding feature of active oxygen scavengers is their ability not only to intercept oxygen from the air as it tries to reach the packaging cavity, but also to provide the means to remove unwanted oxygen (often called excess oxygen). from within the cavity of the packaging where said oxygen may have been inadvertently introduced during packaging or filling. Only active oxygen scavengers can remove unwanted oxygen from the packaging cavity. The capture of active oxygen implies, therefore, the consumption of the material incorporated in the packaging. The material is progressively consumed so that the active oxygen scavenging capacity is eventually depleted or at least diminished. However, this eventual reduction of the active oxygen scavenging part can be adjusted so that the reduction occurs only after the free shelf life within the package of the packed product, which is typically one year or less.

Active oxygen scavengers are known and have been used in a variety of constructions. Optimally, active oxygen scavengers should have most, or at least some, of the characteristics listed below:

ES 2 178 176 T3 (1) Its oxygen scavenging capacity should be present both in the absence and / or presence of water or humidity.

(2) They should have a clarity similar to that of PET or other thermoplastic packaging when necessary for the production of transparent bottles or films.

(3) They should be self-adhesive to adjacent layer (s) when used as layer (s) in multi-layer packaging construction.

(4) They should even be dispersed throughout the packaging to allow an optimal and uniform opportunity to capture oxygen.

(5) They should have glass transition temperatures above filling and storage temperatures (at least 30 C above), so that they exist as solid or solid films for these purposes.

(6) When used as liners containers, they should be capable of being spread over the internal surfaces of a container in an aqueous system (as opposed to a lacquer that would require evaporation of organic solvents).

(7) The decomposition products into which the active oxygen scavengers decompose after reaction with oxygen must not be harmful to the packaged product or must be protected from the packaged product.

(8) The mechanism of its reaction with oxygen must not be detrimental to the strength, transparency or other outstanding characteristics of the packaged article.

What is needed are active oxygen barrier materials that possess as many of the above characteristics as possible, that can be produced at reasonable cost, and that have sufficient oxygen scavengers and barrier properties to offer the possibility of achieving shelf life in the range. six months to two years for oxygen sensitive products. Later this invention addresses such a need.

Summary of the invention and analysis of the state of the art

In a commonly designated, related, and co-pending US application, filed September 23, 1996 and Serial Number 08 / 717,370, it was disclosed that certain hydrocarbons, such as polyolefins (especially polydienes), when presented in small amounts as polyolefin oligomaric blocks in a copolyester polymer block they added substantial active oxygen scavenging capacity to the packaging polyesters that showed no oxygen scavenging capacity, in the absence of the polyolefin oligomeric blocks. The oxygen scavenging copolyesters of the application referenced above were predominantly comprised of packaging polyether segments with only an oxygen scavenging amount, of polyolefin oligomeric segments present to provide the oxygen scavenging capacity required for the packaging request. projected. The co-polyesters of the application Serial Number 08 / 717,370, were in the range of 0.5-12% by weight of polyolefin oligomeric segments, with the remainder comprising polyether segments. An especially preferred embodiment was a copolyether of 4% by weight of oligomeric polyolefin segments, with the remainder being polyether segments. Such polyether blocks comprising low weight percent levels of polyolefin oligomeric segments have properties (such as melting point, viscosity, and transparency) very similar to that of the unmodified polyesters from which the polyether segments are derived. In particular, layers are described above in laminar packaging and bottles with one or more layers of unmodified polyesters and one or more layers of oxygen scavenging co-polyesters blocks, where self-adhesive and packaging articles look like a monolithic construction (mine than laminated ).

In PCT Application Number PCT / US 98/02991 that was filed on February 17, 1998, the concept of implantation of oligomeric polyolefin segments with high oxygen scavenging capacity was extended to polyamides. The PCT Application referenced above, described co-polyamide blocks consisting predominantly of polyamide segments and an oxygen scavenging amount of polyolefin oligomeric segments. As in the previously described case of the co-polyesters, the corresponding co-polyamides have properties very similar to the unmodified polyamides, especially the polyamide from which the polyamide segments are derived. Polyamides are generally considered an inherently superior passive barrier compared to polyesters. Thus, co-polyamides not only have a substantial active oxygen scavenging capacity, but also have better passive barrier properties since they mainly consist of

ES 2 178 176 T3 of polyamide segments. In this application, additional oxygen scavenging parts are described, which when incorporated into co-polyesters or co-polyamides exhibit superior active oxygen scavenging ability as demonstrated in previous related applications. The incorporation of active oxygen scavengers in other polycondensates has also been described, in addition to co-polyamides and co-polyesters. Further on, the incorporation of active oxygen scavenging parts to copolymers of the adicioin type (as opposed to those of the condensation type) is described. Another embodiment of this application involves the incorporation of the previously described oxygen scavenging parts (such as polybutadiene oligomer), into an aqueous spray formulation for use as a liner / coating container to remove excess oxygen from canned goods through of active oxygen capture.

In previous and related patent applications, cited previously, it was disclosed that certain hydrocarbon materials could be adapted for deployment as active oxygen scavengers in packaging articles. These active oxygen scavengers when placed on the walls of a packaging item would intercept and react with oxygen (from the air) as it tries to pass through the wall of the packaging, thus protecting the packaging content from oxygen and spreading the Shelf life within the packaging of oxygen sensitive packaged substances. When used in packaging, active oxygen scavengers can also react and remove excess oxygen from the packaging cavity provided that there is a means for oxygen in the packaging cavity to contact and react with the active oxygen scavenger. The ability of hydrocarbons to react with oxygen is well known in the state of the art and began to attract the attention of researchers in the early twentieth century because the degradation of materials such as car wheels and vegetable oils was not wanted. . Eventually, it was recognized that the hydrocarbon's propensity to oxidize could be used to advantage in packaging, when deployed as an active oxygen scavenger. However, it was necessary to overcome two major obstacles to reduce the phenomenon in practice. First, it was necessary to identify those hydrocarbons that it was reasonable to use, from an economic point of view, but that also had sufficient oxygen scavenging capacity to provide the useful life within the desired packaging. Second, a way had to be found to safely incorporate these materials into modern packaging articles, which could be manufactured using state-of-the-art packaging equipment. Other considerations include transparency of the packaging and the opportunity to recycle the packaging. These considerations were addressed and resolved in previous and related patent applications, cited above.

In these previous and related applications, it was disclosed that hydrocarbons such as polyolefin oligoimers had sufficient commercial oxygen scavenging capacity to extend the useful life within packaging of oxygen sensitive products. Especially effective is the oligomer polybutadiene. It was not entirely understood whether or not this effectiveness is due to the presence of carbon-carbon double bonds (olefinic instauration) in the polybutadiene oligoimer. It was also described that the oligíomers could be functionally terminated with a chemical group capable of taking part in poly-condensation reactions. The functionally terminated polyolefin oligoimers were then incorporated as blocks into a poly-condensate. Copolycondensates, such as co-polyesters and co-polyamides, were extremely compatible with commonly used packaging polycondensates and as such sensitive for use in packaging articles. In this application, this concept has been extended to the use of a polyether oligomer (specifically polypropylene ioxide) as the oxygen scavenger part. There is no olefinic unsaturation in the polypropylene ioxide oligoimer. While not wishing to be bound by theory, it is Applicant's belief that oxygen uptake occurs not only at the -CH2- sites of propylene ioxide, but also at the -O- site of ether.

In order to incorporate the propylene ioxide oligomer into packaging copolycondensates, it was first necessary to add terminal functional groups capable of taking part in the polycondensation of the propylene oxide oligiomer. Subsequently, it was possible to form copolycondensates, such as copolyesters and copolyamides, with segments of propylene ioxide oligíomers. The weight percentage of propylene ioxide oligoimers segments, the molecular weight of the propylene ioxide oligoimers and the mean size of the diameter of the propylene oxide oligomers segments has had to be determined to achieve compatibility, transparency and capacity. optimal capturer, as was the case with copolycondensates with polyolefin oligoomer segments. These propylene oxide oligoomers containing copolycondensates are topically displayed as at least one layer on the wall of a multi-layer packaging article.

American patent No. 5,605,996 (Chuu et al.) Describes the use of propylene oxide rubber as an oxygen scavenger, but it requires the presence of both the olephonic instauration and moisture to function as an oxygen scavenger. The applications of copoli4

ES 2 178 176 T3 condensed with polypropylene oxide oligomer blocks do not contain olefinic unsaturation and capture oxygen both in the absence and in the presence of water (moisture) when provoked with a suitable catalyst. US Patent Number 5,529,833 (Speer et al.) Describes an oxygen scavenging multilayer structure, in which at least one layer consists essentially of an ethyleonically unsaturated hydrocarbon. As noted above, applications of copolycondensates with polypropylene oxide oligoomer blocks do not contain olephonic unsaturation.

The applications reported above are all directed to compositions containing condensation copolymers of polymers, especially polyesters and polyamides. Copolymers are active oxygen scavengers because segment blocks having oxygen scavenging portions have been implanted in the copolycondensates. In the applications reported above, Applicants have described the use of polypropylene, poly (4-methyl) 1-pentene and polybutadiene as oxygen scavenging moieties, which are effective when included in a polycondensate. In this application, the use of the polypropylene oxide oligoomer has been described as an oxygen scavenger part. While many embodiments have been described involving the use of the previously described oxygen scavenging copolycondensates, compatibility with package construction is optimal when oxygen scavenging copolycondensates are used in polycondensate packages. For example, oxygen scavenging copolyethers are most compatible when used with adjacent layers of packaging polyester. In a similar way, oxygen scavenging copolyamides are most compatible when used with adjacent layers of packaging polyamide. While polycondensate-based packaging articles are very common, there is still a wide variety of applications for additive polymer-based packaging articles.

In numerous embodiments of this invention, applicants have extended the concept of incorporating high oxygen scavenging parts into additive polyomers to create additive oxygen scavenging copolymers. These oxygen scavenging additive copolyomers can be used in any suitable embodiment, but are intended, first of all, for use in additive polyomers of packaging articles such as those containing polyolefins including polypropylene, polyethylene, and mixtures of the above. . As was done for polycondensates, Applicants describe the use of polyolefin oligomers, preferably polypropylene, poly (4-methyl) 1-pentene, polybutadiene and also the use of propylene oxide as preferred oxygen scavengers that are effective scavengers. when included in polyadicioon polymers. Later on, the Applicants preferred the method of preparation by transesterification of the prefabricated polyaddiction polymers. Some addition polymers may already have sites for the esterification reaction in the main polymer, for example those containing acrylic acid or derivatives of acrylic acid. Of course, many polyaddition polyomers, such as polyolefins, do not have esterification sites. In such situations, it is generally necessary to treat the spike polymer with a substance that can add the necessary esterification sites to the spike polymer. A preferred class of reagents for such purposes is an unsaturated acid, its anhydride, or derivatives thereof. Maloeic anhydride (or oil derivatives) is especially preferred and such a process is generally well known in the state of the art as a maleation.

For further understanding, it may be useful to consider the following formulas I and II:

I. HO- (OSM) -OH

II. H2N- (OSM) -NH2

In Formulas I and II, OSM represents a divalent oxygen scavenger part, such as polypropylene oxide, or the other scavenger parts mentioned above. Formula I shows the dihydroxy form of OSM and Formula II shows the diamino form of OSM. OSM may have a unique functional group or it may have a degree of functionality greater than 2, but in Formulas I and II dual functionality is shown as one of many possible degrees of functionality. Also, other functional groups attached to the OSM are possible and suitable for the purpose of this invention, but only the hydroxy group and the amino group are shown in the explanation and in the illustration. It will be obvious to those skilled in the art that the entities represented in formulas I and II are capable of entering the polycondensation and / or transesterification reactions. In this invention, Applicants react formula I or II species with additive polyomers having acidic sites (or other suitable reaction sites) and incorporate the OSM into the addition polyomer by condensation or esterification. The net result provides a simple and straightforward method for adding a precise amount of oxygen scavenging capacity in the form of the various OSMs listed above to an addition polymer.

IS 2 178 176 T3

Generally, copolyaddition polymers will predominantly have polyaddition segments and will have only enough OSM segments to provide the required oxygen scavenging capacity for the intended application. Predominantly, in this sense, more than 50% by weight of polyaddiction segments are defined in the oxygen scavenging addycin copolymers. In practice, copolyadic oxygen scavengers would have OSM segments in the range of

0.5 to 12% by weight of the capture copolymers. Preferably, the OSM segments would count from 2 to 8% by weight of the copolymer, and more preferably from 2 to 6% by weight of the copolymer. As was the case for oxygen scavenging copolycondensates, it is desired to use only the minimum amount of OSM segments required, so that the oxygen scavenging addycin copolymers have properties very similar to unmodified addition polymers, especially the addition polymer of which segment is derived. A PCT Patent Application (Ching et al.) Published on December 19, 1996, and designated as WO 96/40799, describes a polyethylene polymer with a main element with esterification / transesterification sites located in the ileum and methods of esterification of said sites. . The Ching et al. Patent further describes attachments (to active sites) in the polymer of protruding groups having a carbon atom with a hydrogen atom attached, where said carbon atom is adjacent to a parts list, as shown. he quotes me later in the description by Ching et al. In practice, the Ching et al. Reference finally describes a composition consisting of a transition metal and a modified polyethylene polymer capable of capturing oxygen in a range of about 40-63 cc per gram of composition after 28 days. The oxygen scavenging copolyadicioin polymers described by Applicants are easily distinguishable from the Ching et al. Disclosure because Applicants' copolymers are capable of capturing about 83 cc of oxygen per gram of copolymer in 28 days under similar conditions, even in the absence of oxygen. a transitional metal catalyst.

In another embodiment of this invention, Applicants describe a method of adding active oxygen scavenging ability to widely used container coating compositions. It is common practice in the packaging industry to use very thin plastic coatings on the inside of metal can surfaces (iron or aluminum) to prevent acidic food and beverages from corrosive attack and contamination associated with ionic metals. Particularly acute is the situation of canned carbonated beverages, such as beer and soda, where dissolved carbon dioxide ensures highly acidic and corrosive conditions. In addition to corrosion prevention, another desirable attribute for can liners is the ability to remove unwanted oxygen from the package cavity where such oxygen has inadvertently been introduced during container filling. In can liners there is little concern regarding oxygen entering the packaging cavity from the outside, since the metal can is essentially a passive oxygen barrier perfect for permeability of exterior oxygen. For the packaging of beer in cans, common technology is capable of placing beer in sealed cans with oxygen levels as low as about 200 PPB. Pasteurization of beer can further reduce the level of oxygen to 100 PPB that remains in the can to react and spoil the beer stored in the metal can. The taste of beer depends mainly on the reaction with trace amounts of oxygen. Subsequent reduction in the amount of leftover oxygen in a beer can provides the means for better tasting beer and / or a longer shelf life for packaging beer in cans, hence the need to line the cans. cans with plastics with active oxygen scavengers.

Some of the most commonly used can coatings are epoxy amine acrylate (EAA) coatings that are sprayed onto an unfilled metal cup (i.e. a can that has not been capped), such as a composition in aqueous solution before doing a short tan of about 2 minutes at about 200 C. Later, similarly tanned and coated can lids are applied to complete the packaging. In all cases, tanning from a sprayer in aqueous solution is more environmentally friendly than evaporating organic solvents from a can. For the coatings of cans intended for use with food, beverages and edible products in general, the advantages of working with a coatings sprayed in aqueous solution versus an organic solvent spray (lacquer) are even more pronounced. The Applicants in this invention describe a method for incorporating the above formula I and II species into a water-based can liner emulsion, adding oxygen scavenging capacity to the formed can liner. A PCT Patent Application (Bansleben et al.), Published September 12, 1997 and designated WO 97/32925 describes active oxygen scavenging can liners. However, the Bansleben et al. Reference describes only the use of an oxygen scavenging "lacquer" that can be used as a coating on cans and other rigid containers. While there are other major differences, Applicants' can coatings are easily distinguished from Bansleben et al. Coatings in that they are formed from a water-based emulsion and applied to the can as a spray in aqueous solution as opposed to lacquer.

IS 2 178 176 T3

Brief description of the drawings

Figure 1 is a cross-sectional view of a preferred oxygen scavenging bottle wall and film construction.

Figure 2 is a graph showing the oxygen uptake of oxygen scavenging addition copolymers, over a period of 28 days at 60 ° C.

Figure 3 is a graph showing the amount of oxygen captured per gram of can liner material for various can liner compositions.

Figure 4 is a graph showing the oxygen scavenging capacity of various blocks of condensation copolymers of this invention.

Detailed description of the invention

The embodiment serves to solve the problem of how to incorporate a solid polymeric oxygen scavenger substance into a can liner in such a way that the inclusion of the oxygen scavenger does not denigrate the viscosity / rheology characteristics of the aqueous emulsion. It is generally more environmentally friendly to apply plastic coatings to cans through a sprayer in aqueous solution or an emulsion better than non-aqueous alternatives where the spray is in the form of a lacquer based on organic solvents that must eventually be evaporated in order to form the lining of the can. This is even more important for lining cans than tin cans intended to contain edible products.

The use of epoxyamine acrylate (EAA) formulations applied as aqueous sprays for can coatings is already widely in use commercially. Billions of containers are coated annually with such formulations.

Typical formulations of these coatings are ICI / Glidden's aqueous emulsions (EAA) that routinely contain 18% solid in the emulsion. Applicants have found that oxygen scavenging properties can be added to such a coating by directly including a small amount of the species previously described in formulas I and II. Species of Formulas I and II are preferred for can coatings when the OSM is a polybutadiene oligomer or a polypropylene oxide oligomer. Especially preferred is the dihydroxy-terminated polybutadiene oligomer for its high oxygen scavenging capacity and commercial availability.

In all cases, an objective of this invention is to use the minimum amount of OSM necessary for the modified compositions to remain with similar properties to the unmodified compositions. In this embodiment, using only a small amount of OSM serves to make the modified EAA as similar as possible to EAA without the addition of OSM. Conducting spraying experiments, using equipment similar to those used for the production of can coatings, Applicants determined that EAA reactive dispersions with a range of 1 to 5% by weight (relative to the weight of the solid in the dispersion), of functionally terminated OSM were still essentially identical in physical properties to unmodified EAA. Also the addition to the EAA mixture of a transition metal in the range of 10-500 PPM (calculated as metal with respect to the weight of the solids in the emulsion), which serves as a catalyst for the reactions of OSM with oxygen, does not They adversely affect the sprayer and / or the tanning properties of the emulsion in aqueous solution. Cobalt is the preferred transition metal catalyst and cobalt added in the carboxylate form is especially preferred, but cobalt octoate cobalt is especially preferred. Other spray tests were done where the composition comprised 50 to 500 PPM (based on the weight of solids in the emulsion) of benzophenone (BNZ) to increase the proportion of oxygen captured by OSM. Again, EAA compositions comprising (1) functionalized OSM and transition metal or (2) functionalized OSM transitional metal and BNZ, were found to spray and tan in a can liner in a manner virtually identical to that of the EAA not modified when deployed in the ranges mentioned above.

The Applicants further determined that the OSM, the transition metal and the BNZ could be added directly and independently of the EAA emulsion or that the OSM, the transition metal and the BNZ could be mixed and then added to the EAA emulsion. Applicants' preferred method of preparing the formulation comprised mixing at least the OSM and the transition metal catalyst prior to mixing with the EAA emulsion. Regardless of the order in which the components of the composition are mixed or added, it was necessary to store the composition

ES 2 178 176 T3 formulated in an inert environment, such as under a nitrogen blanket, to prevent degradation (caking / thickening) of the final composition prior to spraying. Even when stored under nitrogen, modified emulsions should be applied within 72 hours of formulation for best results. As determined in the reported applications, a molecular weight of OSM in the range of 1000-3000 produces good results and is preferred. The decomposition products of the OSM used in the compositions of this invention (after reaction with oxygen) are not precisely known, nor is there any reason to believe that they may be toxic. However, Applicants prefer to practice this invention by using two thinner coatings of the EAA emulsion to form the can coat. A first coat of the EAA emulsion containing the oxygen scavenging additives (OSM, transition metal and BNZ) is sprayed directly onto the metal of the can (usually iron or aluminum) and at least partially tanned. Then a second coating of unmodified EAA emulsion is applied and tanned. As has been the case in reported cases, such a liner construction allows only the unmodified EAA to be in contact with the can cavity and / or its contents. In such a construction, it would be necessary for the excess oxygen to permeate, through the second (inner) coating of EAA to reach the OSM and react with oil. All reaction products are isolated from the can cavity and its contents by the inner EAA liner. Conversely, the contents of the can cavity are isolated from the modified EAA coating.

A review of the conditions of use of a 12 oz (355ml) beer strength, helps us to understand some of the subsequent necessary considerations. Such a beer can when commercially sprayed with an EAA emulsion in the form of a cup (i.e. a beer can without a lid) typically ends with a tanned coating weighing about 0.1g. The can lid is added later and may also be lined with modified oxygen scavenging EAA or unmodified EAA. In the Examples section of this application it was shown that a tanned oxygen scavenger EAA can liner formulation has 2.7% by weight of OSM, 200 PPM of transition metal and 200 PPM of BNZ consumes in excess of 5.0 cc per gram at room temperature and pressure, about 70 days. Theoretically later, the 0.1 grams of material present in the tin cup liner can consume about 0.5cc of oxygen in 70doas. Most American beer producers estimate that more than 95% of their beers are in the hands of their consumers 60 days after bottling / canning, so that a useful life inside the bottle of 70 days would count towards the distribution of most of the canned beer. As noted previously, state-of-the-art beer packaging technology is capable of filling beer cans with as little oxygen as 100 PPB that remains in canned beer after pasteurization. From this it can be calculated that when a 12 oz can of beer is filled with 100 PPB of oxygen, it contains about

0.025 cc of oxygen at room temperature and pressure. Thus, in this hypothetical case, there is a theoretical excess of 20 times of available oxygen scavenging capacity. The utilization of EAA containing 5% by weight OSM can be increased to 40-fold excess, but can be reduced again to 20-fold excess if the can is lined with two layers, each of which is just the half as thick as a single layer of lined tin. A 20-fold excess theoretical oxygen scavenging capacity is reasonable in view of the need for the void space oxygen to permeate through the inner EAA layer that defines the can cavity before it reaches the EAA layer with the OSM.

While the description has been made entirely in terms of can coating, those skilled in the art recognized that many container constructions could benefit from the described oxygen scavenging compositions and their method of use. The application of the features of this invention to containers other than cans is envisioned by the Applicants and is considered within the scope of this invention. For example, PPG Industries produce a series of water-based EAA emulsions, applied as sprays in aqueous solution to form an inner liner for polyester (PET) and other plastic containers sold under the BAIROCCADE® brand. Modification of the PPG emulsion to include OSM, transition metal, and BNZ in the same proportions as described above for can liners could give an oxygen scavenging liner for plastic containers. Plastic bottles often have harmful amounts of oxygen dissolved in them or adsorbed on the plastic walls of the bottle. The application of an active oxygen scavenging liner to such bottles will suffice to remove such dissolved or adsorbed oxygen. As in the case of can liner, a preferred embodiment would be the application to a bottle of a modified layer followed by an interior unmodified layer that forms the surface of the packaging cavity. Polypropylene oxide oligomer as an oxygen scavenging part

In the above reported applications, copolycondesates (such as copolyethers and copolyamides) with segments of oxygen scavenging moieties (OSM) consisting of oligoomers of

ES 2 178 176 T3 polyolefin. More specifically, the polyolefin oligiomers used were selected from the list consisting of polypropylene, poly (4-methyl) 1-pentene, and polybutadiene. These polyolefin oligoimers were first provided with terminal functional groups (usually dual functionality) capable of taking part in the polycondensation and transesterification reactions and later included as a lower percentage (on a weight basis) of the copolycondensate segments. The use of a typical weight range involves copolycondensates consisting of 0.5 to 12% by weight of polyolefin oligomer segments. Copolyster species of this type with high oxygen scavenging capacity were found, which existed as solids at room temperature in the range of 0 ° C to 60 ° C, and had good transparency, especially when (1) were used as adjacent layers to an unmodified polyether layer, (2) were used in the presence of an added transition metal as a catalyst for oxygen capture (i.e. the transition metal catalyst was added in addition to the residual catalyst present from the copolymer formation), (3) it was subjected to a biaxial orientation of a 2.5 x 4.0 extension, (4) they were manufactured by transesterification in an extruder reagent, and (5) had pyromellitic dianhydride added during formation as a chain extending agent to achieve the optimum molecular weight for the copolyether.

The Applicants now describe the use of the polypropylene ioxide oligomer as an OSM in a manner similar to that previously described for polyolefin oligoimers. Of course, the polypropylene ioxide oligomer must first be functionalized at its ends with groups capable of taking part in the polycondensation and / or transesterification reactions. Formulas I and II above show various options for such end-functionalized species and reveal how many species can participate in polycondensation and / or transesterification. In Formulas I and II, OSM can represent a divalent polypropylene ioxide oligomer with a low molecular weight (MW) typically in the range of 100 to 10,000 and preferably in the range of 1000 to 3000. The use of low MW polypropylene ioxide oligíomers helps to ensure a more uniform dispersion of the polypropylene ioxide oligomer segments through the oxygen scavenging copolycondensates. Low molecular weight polyolefin oligiomer has also been found to lead to improved transparency in applications where transparency is of importance.

Formulas I and II show difunctionality in the polypropylene oxide oligoimer but the polypropylene oxide oligomer may be monofunctionalized or functionalized to a greater degree than

two. Only hydroxy and amino functionality are shown in Formulas I and II as examples that will react, but those of ordinary skill in the art recognize that many other options are possible including carboxy, epoxy, alkoxy. Functionalization of the polypropylene ioxide oligomer is not, per se, part of this invention and such end-functionalized species are well known in the art and are commercially available. The copolycondensates of this invention can be prepared by direct techniques (continuous and / or discontinuous) up to the degree of capture capacity necessary by substituting a molar equivalent amount of the formula I or II species, for example, by the same molar amount of monoimer. with similar functionality at the ends that would normally be used to prepare the unmodified polycondensate.

The Applicants also disclose the use of another class of oxygen scavenging moieties which can be broadly designated as aromatic compounds with methyl chains. Applicants' observations indicate that -CH2- groups attached to aromatic nuclei have commercially acceptable oxygen scavenging capacity. For this invention, aromatic substances with methyl chains and have at least one methyl group attached to the aromaitic core are defined to be aromatic chemicals. Examples of aromatic substances with methyl chains are toluene, xylenes, trimethylbenzenes, mono, di, tri, etc., methyl naphthalenes. One requirement of such compounds is that they must be attached to the copolycondensate by a bond to one or more methyl carbon atoms regardless of their bond to the aromatic part of the molecule. Examples of such aromatic substances with methyl chains after dual functionalization and according to the species in Formula I above include dihydroxymethyl benzenes and dihydroxymethyl naphthalenes. These compounds can be monofunctionalized or functionalized to a degree greater than 2, providing mine of two groups of methyl chains. In a similar way, in a similar way the above diamine counterpart satisfies the conditions of Formula II. It is important to note that the use of polypropylene oxide oligoimer or aromatic compounds with a methyl chain such as OSM lead to the formation of copolycondensates devoid of olefinic unsaturation; none were present in the unmodified polycondensate.

Applicants prefer to prepare the copolycondensates by transesterification in a reactive extruder. This is achieved by melting the unmodified polycondensate in a reactive extruder and simultaneously introducing the desired weight percent functionalized OSM such as propylene ioxide oligoimer into the melt. Under appropriate conditions, transesterification occurs resulting in

ES 2 178 176 T3 the formation of a copolycondensate block with, for example, polypropylene oxide oligoimer segments and polycondensate segments. Generally the transesterification is done under vacuum and optionally in the presence of a transition metal transesterification catalyst. Cobalt is the preferred catalyst, and cobalt deployed in the carboxylate form of cobalt is especially preferred, with cobalt octoate being the most preferred catalyst. When using the catalyst it unfolds in the range of 10-300 PPMs from the mix in the extruder. Only the amount of propylene oxide oligomer or other OSM segments necessary to meet the required oxygen scavenging capacity are introduced into the copolycondensate. In all cases, the copolycondensate consists predominantly (more than 50% by weight of the segments) of polycondensate segments. It is desired, however, to manufacture oxygen scavenging copolycondensates with properties as similar as possible to the unmodified polycondensates, especially the polycondensate from which they are derived. As such, the amount of propylene oxide oligoimer or other OSM segments is typically within the range of 0.5 to 12% by weight of the copolycondensate, preferably 2 to 8% by weight and mine preferably 2 to 6%. by weight of the copolycondensate.

The copolycondensates formed by transesterification in a reactive extruder are capable of capturing oxygen in the solid state (below their crystal transition temperatures T_(g)) and in the absence or presence of water or humidity. It is desirable to form copolycondensates that are solid in heavy environments, storage and temperatures from 0 ° C to 60 ° C. It is frequently necessary to add a chain extending agent to the reactive extruder to form the copolycondensates with T_(g) above 60^°C. The chain extending agent is typically deployed in the range of 10 to 5000 PPM based on the weight of the mix in the extruder. While there is some minor weight loss due to volatile materials, it should be noted that the chain extending agent would be present in the resulting copolymer, to the same extent as is in the extruder. Aromatic anhydrides with preferred chain extenders and pyromellitic dianhydride is especially preferred.

Applicants envision the formation and use in packaging articles of different types of oxygen scavenging polycondensates. A non-limited list of polycondensates, to which the polypropylene glycol oxide oligomer and other OSM segments can be added, include polyesters, polyamide, polysulfones, polyols, polyethers, polyketones. The reaction conditions in the extruder for the formation of the copolycondensates vary depending on the nature of the supply of the polycondensate. To some extent, the extruder temperature profile is related to the melt temperature of the polycondensate supply. For example, a temperature range of about 250^°C-280^°C for the formation of copolyesters, while using a temperature range of about 280^°C-300^°C for copolyamides. Extruder residence times are typically in the range of

2-5 minutes. Those of ordinary skill in the art will recognize the need to adjust and optimize the reaction conditions of the extruder to match the properties of the polycondensate supply. Typically, the extruder reaction is carried out under vacuum to remove volatile components. The copolycondensate formed is extruded as pellets or through a slot die and made into film. In any case, the copolycondensate is sealed in air and moisture proof containers in an inert environment, such as under a nitrogen blanket until they are necessary for the manufacture of packaging articles.

In one embodiment the oxygen scavenging copolycondensates of this invention are deployed as a layer adjacent to an unmodified layer of the same polycondensate, especially the polycondensate from which the segment of polycondensate in the copolycondensate is derived. In such a packaging construction, the adjacent layers have nearly identical physical properties lending themselves to handling in existing packaging equipment for unmodified polycondensates. Also, adjacent layers tend to be self-adhesive and appear to be a monolithic construction. The wide use of polyesters and polyamides in the packaging industry implies that oxygen scavenging copolyesters and copolyamides would be the copolycondensates of choice for use in the embodiment described above.

An especially preferred type of packaging wall, bottle wall, or film construction consists of a three-layer embodiment, as shown in Figure 1. The exterior of the bottle or packaging wall 24 is formed by a layer 26. It is a thick layer of unmodified packaging polycondensate and may be wholly or partly composed of recycled material, provided that it is not in contact with the packaging cavity or the packed material. The interior of the wall 22 of the bottle or package defining the package cavity is formed by a thin layer 28 of unmodified packaging polycondensate. The central layer 30 is composed of the oxygen scavenging copolycondensates of this invention, that is, those with propylene oxide oligomer segments, for example. The core layer can be thinned with unmodified copolycondensates and typically contain added transition metal catalysts, a photoactive substance, and other routinely used additives.

IS 2 178 176 T3

While the embodiment of Figure 1 may require special extrusion equipment, it is still preferred for the following reasons: (1) Creates a structure with a relatively thick layer of exposed polycondensate that serves as a good passive barrier to oxygen from the air, (2) the inner layer in contact with the packed material is also polycondensate, topically one that has a long history usage and acceptability for consumable packaging, (3) place the copolycondensates of this invention between two layers of unmodified polycondensates with at least reasonable passive barrier properties that isolate the oxygen-scavenging copolymers from direct contact with air and oxygen and preserve their oxygen-scavenging ability that should be applied only to the oxygen that passes through the unmodified polycondensate layers, and (4) the copolycondensates and unmodified polycondensates can be selected to have such similarity that they can be bonded together when co-extruded without the need for or use of an adhesive bonding layer.

The preferred three-layer embodiment described above is most readily achievable by co-extruding one layer of copolycondensates with the two layers of unmodified polycondensates. Thus, the copolymer is chemically similar to the unmodified polymer to which the three layers uniformly adhere to each other and form a monolotic structure when cooled. Adhesive bonding layers are not required. However, in the articles of manufacture of this invention where recycling is not important, additional (and possibly diverse) layers can be incorporated to improve adhesion, improve barrier properties, reduce costs. It may be possible to achieve the preferred three-layer embodiment by techniques other than co-extrusion, such as solution coating or heat melting of separate layers. Any other method other than co-extrusion may have disadvantages of (1) reduction of the scavenging potential due to unwanted and / or inadvertent exposure of the oxygen scavenging copolymers to air or oxygen; and (2) additional steps in the process. For bottle manufacturing, bonding the three layers by adhesives can work against the recycling goal, unless the adhesive is based on copolycondensate / polycondensate. For film and wrap production, recycling is not as important a consideration as it is for bottles. In fact, for films, it may even be desirable to use layers of the copolymers of this development in conjunction with layers of various other materials such as layers of polyethylene vinyl alcohol and layers of polyolefin. While immediate co-extrusion of these copolymers may be the most preferred use of them, other use options are also available, for example the copolymers may be blended as a concentrate with other polycondensates for film or bottle manufacture, or they may be used as inner liners or layers in a multilayer construction, for example in electronic component packaging.

In a more extensive embodiment, this invention discloses a laminar composition that was composed of at least one layer of packaging material and at least one layer of an active oxygen scavenging copolycondensate that is predominantly composed of polycondensate segments and a scavenging amount of active oxygen from OSM segments such as polypropylene oxide oligoomer segments. Predominantly, as used above, the copolymer is at least 50% by weight of polycondensate segments: Topically, OSM segments are composed of 0.5 to 21% by weight of copolycondensate, preferably 2 to 8% by weight. weight and more preferably 2 to 6% by weight of copolymer. The packaging material layer is topically a thermoplastic packaging material and normally one selected from the list of thermoplastic materials considered safe for use with food, as listed in USA 21 CFR δ 177.1010-177.2910 (revised April, 1997 edition) . However, the copolycondensates of this invention can be used as active oxygen scavengers to consume oxygen from the void space as an inner liner in glass cans or jars / bottles. In these applications, the packaging material layer could be made of metal or glass. The preferred layer of the packaging material is composed of polycondensate and especially preferred are the polycondensates from which the polycondensate segments of the copolymer are derived.

However, a significant advantage of the oxygen scavenging copolycondensates of this invention is that they exist as solids at room temperature and therefore can be made into films or layers regardless of their strengths and likely use as layer (s) in a multilayer wall of a packing item. As such, the polycondensates of this invention predominantly with polycondensate segments and an oxygen scavenging amount of OSM segments such as polypropylene oxide oligoomer segments can be used in packaging articles as layers in a multilayer wall of the packaging article without take into account the nature of the other layers on the wall. Thus, the other layer (s) on the wall can be any packaging material including thermoplastics, glass, metal cans (iron or aluminum), cardboard. Thermoplastic packaging materials used as layers in conjunction with the copolycondensates of this invention will be topically those listed in USA 21 CFR δ 177.1010-177.2910 (revised April 1997 edition). Especially preferred thermoplastics are polyesters, polyamides, polyolefins, and polyethylenevinolic alcohol.

IS 2 178 176 T3

To optimize the oxygen scavenging properties of the copolycondensates, catalysts are frequently added to increase the capture of oxygen by the copolycondensates. The catalysts used are transition metals and are typically added to the copolymer during the manufacturing stage of the packaging article. The transition metal is added in the range of 10-2000 PPM with respect to the weight of the copolymer and is added in addition to the remaining residual catalyst (if any) used to make the copolycondensate by direct polymerization or transesterification. For reasons not fully understood by Applicants, the addition of transition metal catalysts in the specified range also appears to improve the transparency of polycondensates, especially after biaxial orientation. Cobalt is the preferred catalyst. Especially preferred is cobalt added in the form of cobalt carboxylate, and most especially preferred is cobalt added in the form of cobalt octoate.

Applicants have also discovered that the use of a photoactive substance, such as benzophenone (BNZ), increases oxygen uptake by the copolycondensates of this invention. As with the transition metal catalyst, BNZ is typically added to the polymer during the manufacturing stage of the packaging article in an amount ranging from 10-500 PPM based on the weight of the copolycondensate.

In certain packaging applications, the transparency of the copolycondensates of this invention and the transparency of the walls of the packaging that are composed of a layer of copolycondensates of this invention are important considerations. Applicants have found that the biaxial orientation of the copolycondensates of this invention improves transparency further than expected, simply by the decrease in layer thickness due to spreading. The biaxial orientation of the copolycondensate is normally achieved by subjecting the copolymer to a 2.5 x 4.0 extension, typical of the industry in the production of plastic bottles and packaging. The oxygen scavenging copolycondensate can be first biaxially oriented and then incorporated into a packaging article or the biaxial orientation can be performed simultaneously with the other layer (s) comprising the multilayer wall of the packaging.

Oxygen Scavenging Addition Copolymers

The oxygen scavenging copolymers copolymers disclosed above and in related applications provided for an especially advantageous embodiment in which the modified condensing polymer (i.e., the oxygen scavenging copolymer with OSM) is deployed as a layer on the wall of the article. packaging adjacent to a similar unmodified condensation polymer layer, especially the polycondensate from which the polycondensate segments in the copolycondensate are derived. In 1929 Carothers (WH Carothers, J. Am. Chem. Soc. 51,2548 (1929)) proposed a useful general difference between two broad classes of polymers. One of Carothers' classes were condensation polymers, in which the molecular formula of the (repeating) structural unit or units in the polymer lacked certain atoms present in the monomer or monomers from which it was formed, or which could degrade by chemical means. The other class of Carothers were the polymers of addicioin in which the molecular formula of the (repeating) structural unit (s) in the polymer is identical to that of the monoimer from which the polymer is derived. As polyolefins, especially those derived from the monoimer ethylene, propylene or styrene, they continued to be important in the packaging industry. Examples of such packages typically include chilled plastic milk and juice bottles. As previously disclosed, the use of oxygen scavenging copolycondensates as layers on the walls of addicon polymer-based packages is a possibility, but does not provide an opportunity to achieve optimal construction of extreme similarity in properties for adjacent layers in the packing wall. In an effort to solve this problem, Applicants disclose oxygen scavenging copolymers that are predominantly composed (more than 50% by weight) of polyaddition segments and an oxygen scavenging amount of OSM segments. A typical range of use will consist of copolymeric polymers. that are composed of OSM segments in the range of 0.5 to 12% by weight of the copolymer. The preferred range of OSM segments is 2 to 8% by weight and especially preferred is 2 to 6% by weight of the copolymer. The OSM envisioned for use includes polyolefin oligoimers such as polypropylene, poly (4-methyl) 1-pentene, and polybutadiene; polypropylene ioxide oligomer and aromatic compounds with methyl chains. Preferred OSMs are polybutadiene oligiomer and polypropylene oxide oligoimer.

As was the case for oxygen scavenging copolycondensates, the oxygen scavenging copolymers of this invention are preferably made by transesterification. For this to happen (1) it is necessary that the OSM have functionality at its ends (such as that des12

ES 2 178 176 T3 described by formulas I and II) capable of being part of condensation / transesterification reactions, and (2) there must be reaction sites (for example, acid sites, anhydrous sites, other sites, -hydroxy sites , ester sites) in the unmodified addition polymer to be transformed into an oxygen scavenging copolymer. Many addition polymers have such reaction sites available and include those addition polymers that are composed of monomers such as acrylic acid, methacrylic acid, esters of the foregoing vinyl alcohols. Oxygen scavenging copolymers whose segments are predominantly derived from ionomeric polyolefins such as the Surlyn® resin series available from du Pont are also envisioned. For addition polymers without any suitable transesterification reaction sites, it is necessary to first treat the polymer with a compatibilizing agent that added suitable reaction sites to the addition polymer. A preferred class of reagents for adding reaction sites is unsaturated acid, its anhydride, or substituted derivatives of the foregoing. Maleic anhydride (or its derivatives) is especially preferred and such a process is well known in the maleation art. While the availability of such sites in an addition polymer is necessary to produce the oxygen scavenging copolymeric polymers of this invention, addition polymers not modified with such sites are known in the art and are not, per se, a part thereof. invention.

Addition polyomers with reaction sites as described above describe a similar behavior to condensation polyomers in transesterification reactions and react with OSMs that have their ends functionalized with groups capable of forming part of condensation / transesterification reactions, for for example, those described by formulas I and II above. Transesterification is carried out in an extrusion reactor as was done for the preparation of the oxygen scavenging copolycondensates previously disclosed in this and related applications. As previously indicated, those of ordinary skill in the art will recognize the need to adjust the temperature profile of the extrusion reactor to suit the needs of the supply of the unmodified additive polymer. Again, a major consideration in selecting the reaction temperature is the melt temperature of the polymer feed that was made into a copolymer in the extrusion reactor. Surprisingly, many of the other reaction variables remain in ranges similar to those used in the production of copolycondensates. These similar copolymer synthesis parameters include (1) reaction with end-functionalized OSM that are of the same type and PM, (2) reactor residence times, (3) vacuum reaction, (4) utilization of transition metal transesterification catalysts of the type and ranges previously specified for copolycondensates, (5) use of chain extenders to achieve the preferred molecular weight of the copolymer, (6) extrusion of the copolymer into pellets or films, and (7) storage of the pellets or copolymer films in sealed containers under nitrogen.

The method of using the oxygen scavenging copolymers is also anaologous to that disclosed for the oxygen scavenging copolycondensates. Oxygen scavenging addition copolyomers are usually deployed such that they comprise at least one layer in a wall of a multi-layer package wall. In a number of embodiments, the oxygen scavenging copolyomers are used in constructions where other layer (s) on the wall of the multi-layer packaging are composed of other packaging materials such as glass, metal cans such as aluminum or iron, cardboard. , thermoplastics, (especially those listed in USA 21 CFR δ 177.1010-177.2910 revised April, 1997 edition), or other suitable packaging materials. For such constructions the preferred packaging materials present in the other layer (s) on the wall of the multi-layer packaging are additive polyomers, and especially preferred is the additive polymer from which the additive polymer segments in the capture copolymer are derived. of oxygen. Transition metal catalysts and photoactive materials (BNZ) can optionally be added in the manner and amount previously disclosed for oxygen scavenging copolycondensates. The oxygen scavenging addition copolymers may optionally be biaxially oriented in the amount and manner previously disclosed for oxygen scavenging copolycondensates.

Examples

Examples 1-2

Examples 1 and 2 show the method of preparation of the oxygen scavenging addition copolymers and their oxygen scavenging ability.

Addition copolymer block formation

The oxygen scavenging addition copolymers of this invention can be made on a pilot scale in a Werner and Pfleiderer ZSK-30 extruder. Example 2 and Control Example 1 were processed on a Werner and Pfleiderer ZSK-30 twin screw rotary extruder, with interlocking screws.

ES 2 178 176 T3 completely, with a length 45: 1 to the diameter of the screw. Pellet feed materials were measured in the first section of the extruder using KTRON weight loss pellet feeders. The unmodified feed pellets used for these examples were ethylene methacrylic acid (EMA), a polymer available under the trademark Nucrel® 599 from du Pont. PM 1230 Polybutadiene Oligomeric Diol (PBD) (R20LM available from Elf Atochem) is a viscous liquid and is transported separately using a Ruska piston style pump. The diol was injected directly onto the screw diameters 15 of the last portion of the EMA ball supply at which point the copolymer balls were completely melted. A vacuum of at least 76.2cm (30inches) was placed in a side port of the extruder through a 15.2cm slot die manufactured by Extrusion Dies, Inc. (EDI) (a 6inches EDI slot) over a chimney. from two cooling rolls and then recovered as film on a constant tension winder. After recovery, the films were placed in heat sealed folded bags, nitrogen purged, and then sealed. The extrusion reactor conditions were as noted in Table 1 below.

The pressure values ​​listed in Columns 9 and 10 of Table 1 are those indicated by the pressure criterion.

TABLE 1

Preparation of Addition Copolymer Blocks Extrusion Conditions

<td>Sample- tra</td><td>Velocity screw</td><td>Torque</td><td>Relationship from polymers</td><td>Relationship from addition</td><td>Percentage of additive (w / w)</td><td>Product shape</td><td>Empty</td><td>Departure from extrusion</td><td>Die</td>

<td>1EMA</td><td>60rpm</td><td> 85%</td><td>6.8Kg / h (15Lb / Hr)</td><td></td><td>NA</td><td>Film</td><td>71.1cmHg (28.0 in Hg)</td><td>68.9 bars (1000Psig)</td><td>68.9 bars (780Psig)</td>

<td>2EMA Modi- fied</td><td>123rpm</td><td> 53%</td><td>6.0Kg / h (15.2Lb / Hr)</td><td>272g / h (0.6Lb / Hr)</td><td> 4,00 %</td><td>Film</td><td>71.1cmHg (28.0 in Hg)</td><td>37.9 bars (550Psig)</td><td>49.0 bars (710Psig)</td>

Temperature in ^◦C of the strusioon zone

<td>Show</td><td>Zone 1</td><td>Zone 2</td><td>Zone 3</td><td>Zone 4</td><td>Zone 5</td><td>Zone 6</td><td>Zone 7</td><td>Zone 8</td>

<td>1EMA</td><td> 120</td><td> 150</td><td> 175</td><td> 175</td><td> 175</td><td> 175</td><td> 175</td><td> 175</td>

<td>2EMA Modified</td><td> 120</td><td> 150</td><td> 175</td><td> 200</td><td> 230</td><td> 230</td><td> 175</td><td> 175</td>

<td>Show</td><td>Zone 9</td><td>Zone 10</td><td>Zone 11</td><td>Zone 12</td><td>Zone 13</td><td>Zone 14</td><td>Gear Point</td><td>Die</td>

<td>1EMA</td><td> 175</td><td> 175</td><td> 175</td><td> 200</td><td> 200</td><td> 200</td><td> 200</td><td> 200</td>

<td>2EMA Modified</td><td> 175</td><td> 175</td><td> 175</td><td> 200</td><td> 200</td><td> 200</td><td> 200</td><td> 200</td>

Oxygen Capture from Addition Copolymer Blocks

Oxygen capture was tested using 10g film samples. The samples were placed in 500 cc sample jars with normal air, sealed and then kept at 60 C for the duration of the test. No transition metal catalysts or photoactive compounds were added to the samples. The amount of oxygen as a percentage in the gas (air) of the void space was tested regularly over a period of 28 days through a septum in each sample jar. The oxygen present was monitored on a Mocon HS750 oxygen analyzer by isolating 3 cc of gaseous aliquots in

ES 2 178 176 T3 periodic intervals during the 28-day period of the test. The data for these samples are graphically shown in Fig. 2. Surprisingly, there was virtually no oxygen capture by the control EMA polymer of Example 1, which may be due, in part, to the absence of the transition metal catalyst. After an induction period of about five days, the copolymer samples with 4% by weight PBD oligomer segments showed dramatic oxygen uptake and had consumed virtually all of the oxygen in the jar on day 14. Since the Sample jars of the copolymer started with about 102 cc of oxygen (20.9% of 490 cc), it can be seen that the capacity of the copolymers with 4% by weight of PBD is about 10 cc / g of copolymer after only 14 days. The actual capture capacity after 28 days could not be calculated from Example 2 since, essentially, there was no oxygen left in the sample jar to capture after day 14.

Examples 3-6

Examples 3-6 would show the method of preparing an EAA oxygen scavenging container liner and its ability to capture oxygen. 100g of ICI / Glidden aqueous reducible liner spray, Product Designation 640 C 696 (18% solid), whose composition is listed in Table 2 were placed in a glass jar. To this aqueous emulsion was added 0.48g of Elf Atochem R45 HT polybutadiene diol (PBD MW 2800). When dried as a can liner, the dry liner was comprised of 2.7% by weight of PBD. The mixture was stirred magnificently for one hour, then put on a lid and sealed until coated in thin-foil aluminum with a flat seal to emulate a can liner. The coated thin sheet was placed in an aluminum foil, which was heated in a laboratory hot plate device to 227 ° C.^°C (440^°F), for two minutes, to obtain a heating in the coating. Seventeen thin sheets (surface area 21 cm x 5.5 cm) were fan-folded, and placed in a 250 cc Mason jar fitted with a metal lid containing a sampling rubber septum. Selected60^°C as the storage temperature in an effort to achieve accelerated testing. This composition and experiment was designated as Experiment 3.

TABLE 2

Aqueous Reducible Liner Sprayer Chemical Composition: ICI / Glidden Paints-Product 640 C 696 (MSDS listed)

<td>Brand name</td><td>Chemical name</td><td>CAS number</td><td>Percentage by weight</td>

<td>Dimethylamine noethanol</td><td>Ethanol, 2- (dimethylamino)</td><td> 108-01-0</td><td> 1-5</td>

<td>Melamine resin</td><td>1,3,5-Thiazine-2,4,6-triamine, polymer with formaldehyde, methylated</td><td> 68002-20-0</td><td> 1-5</td>

<td>N-Butanol</td><td>1-Butanol</td><td> 71-36-3</td><td> 5-10</td>

<td>2-Butoxyethanol</td><td>Ethanol, 2-butoxy</td><td> 111-76-2</td><td> 5-10</td>

<td>Formaldehyde</td><td>Formaldehyde</td><td> 50-00-0</td><td> 0,01</td>

<td>Acrylic latex</td><td>2-propenoic acid, 2-methyl-, polymer with ethenylbenzene, ethyl 2-propanoate and n - ((methylpropoxy) methyl) -2-propenamide</td><td> 64112-61-4</td><td> 5-10</td>

<td>Epoxy ester</td><td>Phenol, 4,4 '- (1-methylethylidene) bis-, polymer with (chloromethyl) oxirane</td><td> 25068-38-6</td><td> 1-5</td>

<td>Resin epoxy acrylic</td><td>2-propenoic acid, 2-methyl-, polymer with (chloromethyl) oxirane, ethenylbenzene and 4,4 '- (1-methylethylidene) bis (phenol)</td><td> 28262-39-7</td><td> 5-10</td>

<td>Water</td><td>Water</td><td> 7732-18-5</td><td> 60-70</td>

IS 2 178 176 T3

Another similar composition and experiment, designated as Example 4, was prepared and performed. For Example 4, 0.48 g of PBD diol was added to the 100 g of EAA emulsion as in Example 3, to achieve the same 2.7% by weight of PBD (based on 100% by weight of solids in emulsion or revised can liner weight) also, 200 PPM cobalt octoate (metal) and 200 PPM benzophenone (BNZ) were separately added to the EAA prior to stirring. The 200 PPM of cobalt and BNZ were calculated with respect to the weight of the solids in the EAA emulsion. As for Example 3, a total coating of 4.5 g (which was 2.7% by weight of PBD) was used in this way to determine the oxygen uptake by periodic sampling during storage at 60^°C under a relative humidity (ORH) of 0%.

Another similar composition and experiment, designated as Example 5, was prepared and performed. The composition of Example 5 was the same as Example 4, except that the 0.48 g of PBD diol, the 200 PPM of cobalt (as metal) of the Cobalt octoate and 200 PPM BNZ were mixed prior to introduction to the EAA emulsion. As in Example 3 and 4, a total coating of 4.5 g (which was 2.7% by weight of PBD) was used in a similar way to determine the oxygen uptake by periodic sampling during storage at 22^°C under a relative humidity (ORH) of 100%. Obviously, a temperature of 22^°C and a relative humidity of 100% emulate, more closely, the conditions inside a can of edible product during storage than the 60^°C and 0% relative humidity used for Examples 3 and 4. Example 6 was the control, where 4.5g of unmodified EAA coating was prepared and tested in a manner similar to those used for Examples 3-5 .

In all three experiments (Examples 3-5) it was found necessary to maintain the modified EAA emulsion in an oxygen-free environment such as under a nitrogen blanket. The presence of air (oxygen) caused the modified EAA emulsions to gel and render them non-sprayable in an industrial complex. Under nitrogen, the modified EAA emulsions did not show any indication of increased viscosity when used for three days of preparation.

The oxygen present in the empty space of the jars was monitored in a Mocon HS750 oxygen analyzer by isolating 3 cc of gaseous aliquots at periodic intervals, during the 85 days of the test. The percentage of oxygen remaining in the void space was converted, by calculations, to the amount of oxygen captured per gram of can liner for each Example 3-6. The results are graphically displayed in Fig. 3. As seen in Fig. 3, it is obvious that the premixed PBD, cobalt octotate and BNZ produce a can liner with a much higher oxygen scavenging capacity. Applicants speculate that the premix concentrate (Ex. 5) provides a better opportunity for closer contact of the catalysts with the PBD than in the dilute mix (Ex. 4). The results of Example 3 without catalyst clearly show a decrease in trapping capacity for formulations that are somehow essentially identical.

Oxygen scavenging copolycondensate blocks

The following examples will show the oxygen scavenging copolycondensate synthesis method of this invention and its ability and ability to perform with active oxygen scavengers. These copolycondensates can be made in a Werner and Pfleiderer ZSK-30 scale pilot extruder. The materials were processed in a Werner and Pfleiderer ZSK-30 twin screw rotary extruder, with completely interlocking screws, with a length 45: 1 to the screw diameter. Pellet feed materials were measured in the first section of the extruder using KTRON weight loss pellet feeders. When more than one pelletized component was supplied in this way, the minor components were exclaimed to the first resin feeder and all feed ratios were maintained by the controls. Liquid components, including polypropylene oxide oligomer, were delivered using a Lewa diaphragm pump, which is supplied from a heated and agitated feeder valve or a Ruska pistol style pump. The OSM, and additives, if any, were injected directly onto the diameters of the bolts 15 of the last portion of the EMA ball supply at which point the copolymer balls were fully melted. A vacuum of at least 76.2cm (30 inchas) was put into a side port of the extruder prior to processing the melt flow through a changeover pump for copolymer production. The copolymer product was recovered by (1) extrusion through a three-hole cable die, cooling the cables in a Sandvic cooling contour, and then pelletizing or (2) extrusion through a 6-inch slot die. manufactured by Extrusion Dies, Inc. (EDI) (one 6-inch EDI slot) on a dual chill roll stack and later recovered as film. After recovery, the copolymer products were placed in heat sealed folded bags, nitrogen purged, and then sealed. The materials prepared for the tests are characterized in Table 3.

IS 2 178 176 T3

HYTREL 5556, 7.5 MFR is an elastomeric polyester available from du Pont. PET 7207 is a polyethylene terephthalate available from Shell. R20LM PBD is a polybutadiene diol oligoomer with a Mw of about 1280 available from Elf Atochem. A-3000 is an oxygen scavenging copolyeoster that is composed of 96% by weight of PET segments and 4% by weight of PBD oligoomer segments. CAPRON 8270 is a polyhexamethylene adipamide available from Allied. JEFFAMINE D-2000 is a polypropylene oxide oligoomer with diamine ends of about 2000 Mw available from Huntsman. P1200 is a polypropylene oxide oligoomer with dihydroxy ends with a Mw of about 1200 available n Dow. BENZO is benzophenone. PEBAX 5533 is an elastomeric polyamide available from Elf Atochem.

TABLE 3

Composition of sample materials

<td>Sample number</td><td>Series day</td><td>Base resin</td><td>Reactive component</td><td>Comments</td>

<td> 19440-118-4</td><td> 02/25/97</td><td>HYTREL 5556, 7.5 MFR</td><td></td><td>Clear pearls, Control</td>

<td> 19440-124-2</td><td> 05/22/97</td><td>PET 7201, IV = 0.72</td><td></td><td>Control</td>

<td> 19440-128-2</td><td> 06/23/97</td><td>PET 7201</td><td>Sure</td><td></td>

<td> 19440-130-2</td><td> 06/26/97</td><td>PET 7201</td><td>Sure</td><td></td>

<td> 19440-131-1</td><td> 06/27/97</td><td>PET 7201</td><td>Elf Atochem R20-LM PBD</td><td>A-3000 Control</td>

<td> 19440-132-1</td><td> 07/01/97</td><td>PET 7201</td><td>Elf Atochem R20-LM PBD</td><td>A-3000 Control</td>

<td> 19440-133-2</td><td> 07/02/97</td><td>CAPRON 8270, MI = 0.5-0.7</td><td>Sure</td><td>Nylon 6 Control</td>

<td> 19440-134-1</td><td> 07/08/97</td><td>CAPRON 8270, MI = 0.5-0.7</td><td>Sure</td><td>Nylon 6 Control</td>

<td> 19440-136-2</td><td> 07/15/97</td><td>PET 7201</td><td>Sure</td><td>Control</td>

<td> 19440-138-1</td><td> 07/16/97</td><td>PET 7201</td><td>JEFFAMINE D-2000</td><td>14.7% JEFFAMIN (NMR)</td>

<td> 19440-139-1</td><td> 07/17/97</td><td>PET 7201</td><td>JEFFAMINE D-2000 / COBALT</td><td>2.0% JEFF (NMR) 250PPM COB.</td>

<td> 19440-140-1</td><td> 07/17/97</td><td>CAPRON 8270, MI = 0.5-0.7</td><td>JEFFAMINE D-2000 / COBALT</td><td>4% JEFF., - 500PPM COB.</td>

<td> 19440-140-2</td><td> 07/17/97</td><td>CAPRON 8270, MI = 0.5-0.7</td><td>JEFFAMINE D-2000 / COBALT</td><td>4% JEFF., -500PPM COB.</td>

<td> 19440-142-1</td><td> 09/09/97</td><td>PET 7201</td><td>Elf Atochem R20-LM PBD</td><td>Ruska's first bomb sample</td>

<td> 19440-143-1</td><td> 09/11/97</td><td>PET 7201</td><td>Dow P-1200</td><td></td>

<td> 19440-144-1</td><td> 05/15/97</td><td>PET 7201</td><td>Dow P-1200 / Cobalt Octoate</td><td>500ppm cobalt octoate</td>

<td> 19440-146-1</td><td> 09/18/97</td><td>PET 7201</td><td>JEFFAMINE D-2000 / COBALT</td><td>500ppm cobalt octoate</td>

<td> 19440-147-1</td><td> 09/19/97</td><td>CAPRON 8270, MI = 0.5-0.7</td><td>Sure</td><td></td>

IS 2 178 176 T3

TABLE 3 (continued) Composition of sample materials

<td>Sample number</td><td>Series day</td><td>Base resin</td><td>Reactive component</td><td>Comments</td>

<td> 19440-147-2</td><td> 09/19/97</td><td>CAPRON 8270, MI = 0.5-0.7</td><td>JEFFAMINE D-2000 / COBALT</td><td>500ppm cobalt octoate</td>

<td> 19440-148-1</td><td> 09/25/97</td><td>PET 7201</td><td>25:75, DOW P-1200 / EA PBD</td><td></td>

<td> 19440-149-1</td><td> 09/25/97</td><td>PET 7201</td><td>25: 75DOW / PBD + CAT + BENZO</td><td>200ppm cobalt, 100ppm benzophenone</td>

<td> 19440-150-1</td><td> 09/26/97</td><td>PET 7201</td><td>50:50, DOW P-1200 / EA PBD</td><td></td>

<td> 19440-151-1</td><td> 09/26/97</td><td>PET 7201</td><td>50:50 DOW / PBD + CAT + BENZO</td><td>200ppm cobalt, 100ppm benzophenone</td>

<td> 19440-154-1</td><td> 10/01/97</td><td>PEBAX 5533</td><td>Sure</td><td></td>

<td> 19440-159-1</td><td> 10/06/97</td><td>CAPRON 8270, MI = 0.5-0.7</td><td>Sure</td><td></td>

<td> 19440-160-1</td><td> 10/06/97</td><td>CAPRON 8270, MI = 0.5-0.7</td><td>Dow P-1200</td><td></td>

<td> 19440-161-1</td><td> 10/07/97</td><td>CAPRON 8270, MI = 0.5-0.7</td><td>Dow P-1200 + Cobalt Octoate</td><td>500ppm cobalt octoate</td>

The samples in Table 3 were tested for their oxygen scavenging ability with the same technique used for Examples 1-2. Ten grams of each sample from Table 3 were placed in 500 ml glass jars, and then the oxygen content of the air in the jar was monitored over a period of 28 days. The jars were subjected to 60^°C and at a relative humidity of 0%. All of the copolycondensates in Table 3 showed a substantial oxygen scavenging capacity, especially when increased with cobalt and / or benzophenone addition. Fig. 4 graphically shows the oxygen capture results obtained for some of the PET copolymer blocks in Table 3.

The examples described above are intended to be illustrative of the numerous embodiments of the oxygen scavenging compositions disclosed in this application. Those skilled in the art would recognize that variations of these compositions, including the use of various additives and additive packaging, are encompassed by the disclosure and are within the scope of the invention.