HK1140454A - Multilayer container for enhanced gas barrier properties - Google Patents

Description

Multilayer container with enhanced gas barrier properties

Cross Reference to Related Applications

[0001] Priority of U.S. provisional application No.60/825,861 filed 2006, 9, 15, is claimed herein under 35u.s.c § 119(e), the entire disclosure of which is incorporated herein by reference.

Technical Field

[0002] The present invention relates to a container having enhanced gas barrier properties, and more particularly to enhancing the carbon dioxide and oxygen barrier properties of a packaged beverage container, thereby extending the shelf life of its contents.

Background

[0003] Polyethylene terephthalate and its copolyesters (hereinafter collectively referred to as PET) are widely used for containers for carbonated soft drinks, juices, water, etc. because they have a combination of good transparency, mechanical properties and gas barrier properties. Despite these desirable characteristics, insufficient barrier properties of PET to oxygen and carbon dioxide gases have limited the use of PET in smaller size packaging and in packaging of oxygen sensitive products such as beer, juice and tea products. There is a wide and urgent need in the packaging industry to further improve the gas barrier properties of PET.

[0004] The relatively high permeability of PET to carbon dioxide limits the use of smaller PET containers for packaging carbonated soft drinks. At room temperature, depending on the size of the container, the permeability of carbon dioxide through PET containers ranges from 3 to 14cc per day or from 1.5% to 2% loss per week. Smaller vessels have a larger surface area to volume ratio resulting in a higher relative loss rate. For this reason, PET containers are currently used only as larger containers for packaging carbonated soft drinks, while metal cans and glass containers are used as smaller carbonated soft drink containers.

[0005] The amount of carbon dioxide retained in a packaged carbonated soft drink determines its shelf life. Typically, carbonated soft drinks are filled with approximately 4 times the volume of carbon dioxide per volume of water. It is generally believed that the end of shelf life is reached in packaged carbonated soft drinks when 17.5% of the carbon dioxide in the container is lost by carbon dioxide leaking through the container sidewall and lid. Thus, the permeability of PET to carbon dioxide determines the shelf life of packaged carbonated beverages and the suitability of PET for use as a packaging material.

[0006] A number of techniques have been or are being developed to enhance the barrier of PET to small gas molecules. For example, external or internal coatings have been developed to enhance the gas barrier properties of PET containers. Coatings are usually strong barriers, inorganic or organic, that slow down gas diffusion. However, the implementation of this technology requires coating equipment that is not commonly used in the production of packaged beverages, and therefore requires a large capital investment, increased energy consumption and increased footprint. In many already crowded beverage packaging plants, no additional space can be selected.

[0007] Barrier additives have been reported to be incorporated into polymers to increase their modulus and gas barrier properties through a mechanism of anti-plasticization. However, in these examples, the structure of the container is single-layered.

[0008] In WO 01/12521, Plotzker et al suggest the use of additives selected from 4-hydroxybenzoate and related molecules to increase the gas barrier properties of PET. This published patent application describes barrier additives of the following structure:

HO-AR-COOR，HO-AR-COOR1COO-AR-OH，HO-AR-CONHR，

HO-AR-CO-NHR3-COO-AR-OH，HO-AR-CONHR2NHCO-AR-OH

in the above structures, AR is selected from substituted or unsubstituted phenylene or naphthalene, and R1, R2, and R3 are selected from C1 to C6 alkyl groups, phenyl groups, and naphthyl groups.

[0009] The additives described in the above prior art provide only moderate improvement in PET barrier properties, with less than a 2.1 fold improvement in oxygen barrier properties (X) for the best example of 5 wt% addition. However, at this level of addition, significant degradation of the PET occurs and the Intrinsic Viscosity (IV) is significantly reduced. Although reducing the amount of additives added reduces the degradation of PET, this also reduces the barrier improvement factor so much that there is no practical benefit in using these additives in packaging carbonated soft drinks or oxygen sensitive foods. The IV loss is due in part to the addition of small molecule additives. Additional IV loss occurs when the additive contains functional groups that can react with PET, resulting in a decrease in molecular weight. Additives with reactive functional groups are more soluble in PET and therefore do not impair the haze in the bottle. PET, with a significantly reduced IV, cannot be used to blow mold containers, such as beverage containers. In addition, containers made from low IV PET have poor mechanical properties, such as creep, decreased impact resistance, and the like. Further, PET containers made from low IV PET have poor crack resistance, which is undesirable in container applications.

[0010] PET has been modified with other components or blended with other ingredients to enhance the gas barrier properties of PET. Examples include polyethylene naphthalate (PEN)/PET copolymer or blend, Isophthalate (IPA) modified PET, blends of PET with polyethylene isophthalate (PEI) or polyamides such as nylon, PET modified with resorcinol based diols. For PET copolymers to achieve moderate barrier enhancement of 2 x or higher, the modification is typically 10 to more than 20 weight percent or mole percent of the total comonomer. When PET is modified to such a high degree, the tensile properties of PET change significantly such that the commonly used preform designs for PET containers cannot be used to produce containers. The use of these PET copolymers to mold the preform for a typical PET container can result in the preform not being fully stretched and the final container can be very difficult, if not impossible, to make. Even if such a container can be made, it cannot exhibit improved gas barrier properties, but rather exhibits deterioration in physical properties, so that it cannot be used for packaging carbonated soft drinks. U.S. Pat. Nos. 5,888,598 and 6,150,450 disclose redesigned thicker-walled PET container preforms to compensate for the increased stretch ratio. However, such thicker preforms require new molds that require additional capital investment. Thicker preforms also have lower productivity because it takes longer to cool and heat the thick-walled preform. Furthermore, blends of PET with polyamides such as nylon tend to turn yellow and hazy, and are no longer as transparent as conventional PET.

[0011] In addition, multi-layer containers have been developed with a high barrier layer sandwiched between two or more PET layers. The materials used for the high barrier layer are typically non-PET polymers such as nylon, polyglycolic acid, EVOH, PEN, and the like. Due to the different materials, multi-layer containers often suffer from delamination problems, affecting the appearance as well as the barrier and mechanical properties of the container.

[0012] There is therefore a need in the art to enhance the barrier properties of PET for use in applications where a stronger barrier is required, for example in packaging carbonated beverages as well as oxygen sensitive beverages and foodstuffs in a manner that does not cause significant degradation of the PET, does not significantly affect the elongation of the PET, and does not negatively impact the clarity of the PET.

Disclosure of Invention

[0013] The present invention addresses the above-described needs by providing a polymeric container with enhanced gas barrier properties.

[0014] In a particular embodiment, the multilayer container includes at least two outer layers comprising a polymer matrix, and at least one barrier layer positioned between the at least two outer layers. At least one barrier layer comprises a first polymer composition comprising a polymer matrix and a low molecular weight additive. In another particular embodiment, the multilayer container includes at least one intermediate layer positioned between the at least one barrier layer and the at least two outer layers.

[0015] Particular embodiments of the present invention provide polymeric containers, such as polyester containers, having enhanced gas barrier properties, particularly to carbon dioxide and oxygen. This makes certain embodiments of the present invention particularly useful for packaging carbonated soft drinks as well as oxygen sensitive beverages and food products. Particular embodiments have enhanced gas barrier properties while retaining acceptable physical properties and transparency.

[0016] Other objects, features and advantages of the present invention will be apparent from the following detailed description and claims.

Drawings

[0017] Fig. 1 is a cross-sectional view of a molded container preform made in accordance with an embodiment of the present invention.

[0018] Fig. 2 is a cross-sectional view of a blow molded container made from the preform of fig. 1 according to one embodiment of the present invention.

[0019] Fig. 3 is a perspective view of a packaged beverage made in accordance with an embodiment of the present invention.

[0020] Fig. 4 is a layer cross-sectional view of a multilayer container of the 3-layer container (a), the 5-layer container (B), and the 7-layer container (C) according to an embodiment of the present invention.

[0021] Figure 5 is a schematic diagram of a system for manufacturing a polymer container with enhanced gas barrier properties according to an embodiment of the present invention.

Detailed Description

[0022] The present invention encompasses an enhanced gas barrier polymer container and a method of making an enhanced gas barrier polymer container. Embodiments of the invention, including the structure and composition of the containers, methods of making them, and their uses, are described below and illustrated in the accompanying drawings.

[0023] The present invention provides a multilayer container having enhanced gas barrier properties. As is well known to those skilled in the art, both single layer containers and multi-layer containers can be made by blow molding container preforms. Examples of suitable preform and container configurations are disclosed in U.S. patent No. 5,888,598, the entire disclosure of which is incorporated herein by reference.

[0024] A container preform 12 is shown in fig. 1, and a container 14 made from such a preform is shown in fig. 2 and 3, according to an embodiment of the present invention. The preform 12 is made by injection molding a polymer matrix and includes a threaded finish 112 that terminates in a lower closure edge 114. Below the closure rim 114 is a generally cylindrical portion 116, the cylindrical portion 116 terminating in a portion 118, the portion 118 generally increasing in outer diameter to provide an increased wall thickness. Below portion 118 is an elongated body portion 120.

[0025] The preform 12 shown in fig. 1 can be stretch blow molded into a container 14. The container 14 includes a body 124 including a threaded neck end 126 defining a container mouth 128, a cap rim 130 below the threaded neck end, a tapered portion 132 extending from the cap rim, a body portion 134 extending below the tapered portion, and a base 136 at the bottom of the container. The container 14 is suitable for making a packaged beverage 138, as shown in FIG. 3. Packaged beverage 138 includes a beverage, such as a carbonated soda beverage, in container 14 and lid 140 that seals container mouth 128.

[0026] The preform 12, container 14, and packaged beverage 138 are only examples of applications in which the preform of the present invention may be used. It should be understood that the method and apparatus of the present invention may be used to make preforms and containers having a variety of shapes. Suitable containers include, but are not limited to, bottles, pails, carafes, coolers, and the like.

[0027] Container 14 preferably comprises multiple layers, and can comprise any number of layers, limited only by the capabilities of the coextrusion apparatus used. Fig. 4A, 4B and 4C illustrate the multi-layer construction of containers according to various embodiments of the present invention. In a particular embodiment, the container 14 includes at least two outer layers comprising from about 99% to about 20% by weight of the container and one or more barrier layers comprising from about 1% to about 80% by weight of the container. In another particular embodiment, the container 14 comprises at least two outer layers comprising from about 99% to about 60% by weight of the container and one or more barrier layers comprising from about 1% to about 40% by weight of the container. In another particular embodiment, the container 14 comprises at least two outer layers comprising from about 99% to about 80% by weight of the container and one or more barrier layers comprising from about 1% to about 20% by weight of the container.

[0028] In one particular embodiment shown in fig. 4A, the container 14 includes two outer layers 210, 212 and a barrier layer 214. The outer layers 210, 212 help maintain the structural integrity of the container 14, while the barrier layer 214 enhances the gas barrier properties of the container. Typically, both outer layers 210, 212 comprise a polymer matrix or a polymer matrix with recycled material, while one barrier layer 214 comprises a first polymer composition comprising a polymer matrix or a polymer matrix with recycled material, and a low molecular weight additive. The composition of the layers will be described in more detail later.

[0029] In another particular embodiment shown in fig. 4B, the container 14 includes two outer layers 220, 222, one or more barrier layers and one or more intermediate layers 224, 228. As discussed above, the outer layers 220 and 222 help maintain the structural integrity of the container 14 and prevent the low molecular weight additives from escaping from the barrier layer or layers, while the barrier layer or layers 224 and 228 enhance the gas barrier properties of the container. The one or more intermediate layers 224 and 228 may serve a variety of functions, such as further ensuring the structural integrity of the container 14, providing adhesion to hold the two outer layers 220, 222 and the one or more barrier layers 224 and 228 together, or further enhancing the gas barrier properties of the container. In another embodiment, the container 14 includes one barrier layer 224 and two intermediate layers 226, 228. In another embodiment, the container 14 includes two barrier layers 226, 228, and one intermediate layer 224. It should be understood that the one or more barrier layers and the one or more intermediate layers 224 and 228 may be positioned between the two outer layers 220 and 222 of the container 14 in any order as would be determined by one of ordinary skill in the art as appropriate, as shown in Table 1. As noted above, the two outer layers 220, 222 typically comprise a polymer matrix or a polymeric matrix containing a recycled material, while the one or more barrier layers 224-228 comprise a first polymer composition comprising a polymer matrix or optionally a polymeric matrix containing a recycled material, and a low molecular weight additive. One or more of the intermediate layers 224-228, independent of each other, can comprise a polymer matrix, a polymer matrix comprising a recycled material, a polymer matrix comprising an additive, a polymer matrix comprising a recycled material and an additive, or an adhesive layer.

TABLE 1 layer composition of multilayer containers

5-layer containerOuter layer barrier/middle layer outer layer

7-layer containerOuter barrier/middle layerBarrier/middle layer outer layer

[0030] In another particular embodiment, shown in figure 4C, the container 14 includes two outer layers 230, 232, as well as one or more barrier layers and one or more intermediate layers 234, 242. As described in the previous embodiments, the outer layers 230, 232 help maintain the structural integrity of the container 14 and prevent the low molecular weight additives from escaping from the one or more barrier layers 234, 242, while the one or more barrier layers 234, 242 enhance the gas barrier properties of the container. The one or more intermediate layers 234 and 242 serve a variety of functions, such as further ensuring the structural integrity of the container 14, providing adhesion to bond the two outer layers 230, 232, the one or more barrier layers 234 and 242, and the other intermediate layers 234 and 242 together, or to further enhance the gas barrier properties of the container. In one embodiment, the container 14 comprises one barrier layer 234 and four intermediate layers 236-242. In another embodiment, the container 14 comprises two barrier layers 236, 238 and three barrier layers 232, 240, 242. In another embodiment, the container 14 includes three barrier layers 234, 240, 242, and two intermediate layers 236, 238. It is understood that the one or more barrier layers and the one or more intermediate layers 234, 242 may be positioned between the two outer layers 230, 232 of the container 14 in any order that one of ordinary skill in the art would determine if applicable, as shown in table 1. As noted above, the two outer layers 230, 232 typically comprise a polymer matrix or a polymeric matrix containing a recycled material, while the one or more barrier layers 234-232 comprise a first polymer composition comprising a polymer matrix or optionally a polymeric matrix containing a recycled material, and a low molecular weight additive. The outer layers 210, 212 also prevent the low molecular weight additives from escaping the barrier layer 214. The low molecular weight additive may be volatile and in some embodiments may diffuse from the barrier layer into the air if the outer layers 210, 212 are not present. The one or more intermediate layers 234-242, independent of each other, can comprise a polymer matrix, a polymer matrix containing a recycled material, a polymer matrix containing an additive, a polymer matrix containing a recycled material and an additive, or an adhesive layer.

[0031] Polymers suitable for use in the outer layer in accordance with embodiments of the present invention may comprise any polymer having a melting temperature or processing temperature above 100 ℃. Non-limiting examples include polyesters, polyamides, polyolefins, polylactic acid, polyimides, and copolymers thereof. In a particular embodiment, the polymer matrix comprises PET. Polymers suitable for use in the interlayer and barrier layers according to embodiments of the present invention include polymers having a glass transition temperature above room temperature. Non-limiting examples include polyesters, polyester copolymers, polyamides, polyethylene naphthalate (PEN), polyethylene isophthalate, copolymers thereof, and the like. PET copolymers are particularly useful because they can be used in a variety of barrier applications, such as films and containers.

[0032] PET copolymers suitable for use in embodiments of the present invention comprise a diol component having repeat units derived from ethylene glycol, and a diacid component having repeat units derived from terephthalic acid. In particular embodiments, the PET copolymer contains less than 20% diacid modification, less than 10% glycol modification, or both, based on 100 mole percent diacid component and 100 mole percent diol component, respectively. These PET copolymers are well known. PET copolymers suitable for use in embodiments of the present invention may also comprise polyesters containing recycled material.

[0033] Polymers, including polyesters such as PET copolymers, have free volume between polymer chains. As known to those skilled in the art, the amount of free volume in polymers such as PET copolymers determines their barrier properties to gas molecules. The lower the free volume, the lower the gas diffusion and the higher the barrier to gas molecules. Desirably, in an embodiment of the present invention, one or more of the barrier layers contains a low molecular weight additive that is at least partially located within the free volume between the polymer chains of the first polymer composition. Without wishing to be bound by any theory, it is believed that the low molecular weight additive acts as an anti-plasticizer in the polymer matrix, reducing the free volume, thereby preventing rotation of the polymer chains and enhancing the barrier properties of the polymer composition.

[0034] The low molecular weight additive may improve the barrier properties of the container when the low molecular weight additive is present in the container in an amount ranging from about 0.2% to about 10% by weight of the container. In another embodiment, the low molecular weight additive is present in the container in an amount ranging from about 2% to about 10% by weight of the container. In another embodiment, the low molecular weight additive is present in the container in an amount ranging from about 2% to about 5% by weight of the container.

[0035] When the low-molecular-weight additive is added in an amount of 10% by weight or more of the container, the barrier property improvement factor (BIF) is considerable; however, the properties of the polymer composition deteriorate, resulting in more difficult formation of the container. BIF can be measured as the enhanced gas barrier (the ratio of the gas transfer rate of the polymer composition without additive to the gas transfer rate of the polymer composition with additive). Without being bound by any theory, it is believed that when the low molecular weight additive in the container is added in the container in an amount significantly greater than 10% by weight of the container, the additive acts as a plasticizer, allowing the polymer chains to rotate, reducing the barrier properties of the polymer composition. When the amount of the low molecular weight additive in the container is less than 0.2% by weight of the container, BIF is insignificant.

[0036] The amount of low molecular weight additive in the at least one barrier layer (a), the amount of the at least one barrier layer in the container (b), and the amount of low molecular weight additive in the container (c) are related to one another as follows:

a·b＝c

[0037] the lower limit of the low molecular weight additive (a) in the at least one barrier layer is limited by the lower limit of the at least one barrier layer (b) in the container. The upper limit of the low molecular weight additive (a) in the at least one barrier layer is limited by the ability of the low molecular weight additive to mix with the composition matrix in the first polymer composition in the at least one barrier layer. Accordingly, in certain embodiments, at least one barrier layer in the container comprises the low molecular weight additive in an amount ranging from about 0.25% to about 25% by weight of the barrier layer, in another embodiment in an amount ranging from about 3.75% to about 25% by weight of the barrier layer, and in another embodiment in an amount ranging from about 3.75% to about 12.5% by weight of the barrier layer.

[0038] In particular embodiments, when the low molecular weight additive is present in the container in an amount ranging from about 0.2% to about 10% by weight of the container, the low molecular weight additive is present in the barrier layer in an amount ranging from about 0.25% to about 25% by weight of the barrier layer. Further, the at least two outer layers comprise from about 99% to about 60% by weight of the container and the at least one barrier layer comprises from about 1% to about 40% by weight of the container.

[0039] In another specific embodiment, the low molecular weight additive in the barrier layer is present in an amount ranging from about 3.75% to about 25% by weight of the barrier layer when the low molecular weight additive in the container is present in an amount ranging from about 2% to about 10% by weight of the container. Further, the at least two outer layers comprise from about 99% to about 80% by weight of the container and the at least one barrier layer comprises from about 1% to about 20% by weight of the container.

[0040] In another specific embodiment, the low molecular weight additive in the barrier layer is present in an amount ranging from about 3.75% to about 12.5% by weight of the barrier layer when the low molecular weight additive is present in the container in an amount ranging from about 2% to about 5% by weight of the container. Further, the at least two outer layers comprise from about 99% to about 60% by weight of the container and the at least one barrier layer comprises from about 1% to about 40% by weight of the container.

[0041] Multilayer containers containing at least one barrier layer having a high additive loading prevent many of the side effects normally associated with the use of high levels of additives. It is clear that the outer layer and any intermediate layer of the container counteract the mechanical adverse effect of the barrier layer or layers on the container, since the modulus, elongation, peak load characteristics are determined in part by the outer layer and any intermediate layer of the container, which contain little or no barrier additives.

[0042] The common disadvantages of multilayer containers can be eliminated by using similar materials for each layer, which can minimize or eliminate the risk of delamination and its associated side effects. Moreover, the advantages of multilayer containers can be realized by using additives in the barrier layer that are too volatile for use in single layer containers. Often, the use of volatile additives in the container can foul the mold, eventually leading to a partial degradation that affects not only the appearance of the container, but also the performance of the container. For example, higher melt and processing temperature polymers, such as PET, are required to incorporate low molecular weight additives, and with conventional injection molding significant plate out can occur, which occurs when material deposits on the surfaces of the injection molding equipment during processing of the polymer. Fouling reduces the operating time of the injection molding equipment, resulting in costly production stoppages to clean the equipment. The use of a multilayer container can significantly reduce or eliminate plate-out due to low molecular weight additives because the low molecular weight additives are located between two outer layers that do not contain the low molecular weight additives and prevent the low molecular weight additives from contacting the injection molding equipment surfaces.

[0043] As mentioned above, the first polymer composition in at least one barrier layer preferably contains a low molecular weight additive. Typically, the low molecular weight additive comprises a compound having a molecular weight of less than about 2000 daltons, a molecular weight of less than about 1500 daltons, or a molecular weight of less than about 1000 daltons. In particular embodiments, the low molecular weight additive comprises an ester, diester or polyester of aromatic or aliphatic nature; amides, diamides or polyamides of aromatic or aliphatic nature, non-limiting examples of which include acetanilide, terephthalamide and nylon 6; cyclic esters bearing one or more ester groups, non-limiting examples of which include lactones, polylactones, caprolactones, and lactides; cyclic amides bearing one or more amide groups, non-limiting examples of which include lactams, polylactams, caprolactam, and alanine anhydride; or mixtures thereof.

[0044] In a particular embodiment, the low molecular weight additive comprises a purine derivative, see co-pending non-provisional patent application 11/532,361, entitled "Container and Composition for Gas Barrier Properties", filed on 9/15 2006, which claims priority to provisional patent application 60/723,751, filed on 10/15/2005, entitled Yu Shi et al. The entire disclosures of these patent applications are hereby incorporated by reference.

[0045] The purine derivatives have the chemical structure shown in formula I

[0046]Wherein R is₁、R₃、R₅And R₇Independently of one another, hydrogen, aromatic amines, alkoxy, aryloxy, alkenyl, alkynyl, or linear, chain, branched or cyclic alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocycle or acyl;

[0047]wherein, t₁、x、x₁、x₂Y and z, independently of one another, are a single or double bond; wherein t ', x', y 'and z', independently of one another, are 0 or 1; wherein x ", y" and w ", independently of each other, are 1 or 2;

[0048]wherein, when x is a double bond, x₁Is a single bond; wherein, when x₁When it is a double bond, x and x₂Is a single bond; wherein, when x₂When it is a double bond, x₁And t₁Is a single bond; wherein when t is a double bond, t is₁And z is a single bond; wherein, when z is a double bond, t is a single bond; wherein, when t is₁When it is a double bond, t and x₂Is a single bond; wherein, when x is a double bond, x' is 0; wherein, when x or x₁When it is a double bond, x' is 1; wherein when y is a double bond, y 'is 0 and y' is 1; wherein, when t or t₁When it is a double bond, t' is 0; wherein, when z and t are single bonds,w' is 2; wherein when z or t is a double bond, w' is 1; wherein, when z is a double bond, z' is 0; wherein, when x, y or z, independently of one another, are a single bond, x ', y ' or z ', independently of one another, are 1;

[0049]wherein R is₂、R₄And R₆Independently of one another, may be moieties bound by single or double bonds.

[0050]Wherein when R is₂、R₄Or R₆When it is a singly-bound moiety, R₂、R₄And R₆Independently of one another, comprises hydrogen, hydroxyl, amino, amido, alkylamino, arylamino, alkoxy, aryloxy, nitro, acyl, alkenyl, alkynyl, cyano, sulfo, sulfato, mercapto, imino, sulfonyl, sulfoxy, sulfinyl, sulfamoyl, phosphonyl, phosphinyl, phosphoryl, phosphinyl, thioester, thioether, anhydride, oximo (oximino), hydrazino, methionyl, phosphoric acid, phosphonato, or a linear, chain, branched, or cyclic alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocycle, or acyl.

[0051]Wherein when R is₂、R₄Or R₆When it is a double bond-bonded structural moiety, R₂、R₄And R₆Independently of one another, containing oxygen, sulfur, CR₈R₉、SO₂Or NR₁₀；R₈And R₉Independently of one another, hydrogen, hydroxyl, amino, amido, alkylamino, arylamino, alkoxy, aryloxy, nitro, acyl, alkenyl, alkynyl, cyano, sulfo, sulfato, mercapto, imino, sulfonyl, sulfoxy, sulfinyl, sulfamoyl, phosphonyl, phosphinyl, phosphoryl, phosphinyl, thioester, thioether, anhydride, oximo, hydrazino, methionyl, phosphoric acid, phosphonato, or a linear, chained, branched, or cyclic alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocycle, or acyl group; r₁₀Containing hydrogen, arylamino, alkoxy, aryloxy, alkenyl, alkynyl,or a linear, chained, branched, or cyclic alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocycle, or acyl group.

[0052]Wherein, when x' is 2, two R are₂The moieties may be the same or different; wherein, when y' is 2, two R are₄The moieties may be the same or different; wherein, when w' is 2, two R are₆The moieties may be the same or different.

[0053] As known to those skilled in the art, the above moieties may be further substituted with hydrogen, halo, hydroxy, amino, amido, alkylamino, arylamino, alkoxy, aryloxy, nitro, acyl, alkenyl, alkynyl, cyano, sulfo, sulfato (sulfato), mercapto, imino, sulfonyl, sulfoxy, sulfinyl, sulfamoyl, phosphonyl, phosphinyl, phosphoryl, phosphino, thioester, thioether, anhydride, oximino, hydrazino, methionyl, phosphoric acid, phosphonato, and other useful functional groups.

[0054] In one embodiment of the compound of formula I, the purine derivative comprises a 7H-purine, which has the chemical structure

Wherein, x and x₂Y and t are double bonds; wherein x is₁、t₁And z is a single bond; wherein x ', y ' and t ' are 0; wherein x ", y", z 'and w' are 1; wherein R is₂、R₄、R₅And R₆Is hydrogen.

[0055] In another embodiment of the compounds of formula I, the purine derivatives comprise compounds having the chemical structure of formula II

Wherein, t₁、x、x₁Y and z are single bonds; wherein x is₂And t is a double bond; wherein w ', x', y ', z', x 'and y' are 1; wherein t' is 0; wherein R is₂And R₄Independently of one another, are doubly bonded moieties containing oxygen, sulfur, CR₈R₉、SO₂Or NR₁₀(ii) a Wherein R is₁、R₃、R₅And R₆Independently of one another, comprises hydrogen, hydroxyl, amino, amido, alkylamino, arylamino, alkoxy, aryloxy, nitro, acyl, alkenyl, alkynyl, cyano, sulfo, sulfato, mercapto, imino, sulfonyl, sulfoxy, sulfinyl, sulfamoyl, phosphonyl, phosphinyl, phosphoryl, phosphinyl, thioester, thioether, anhydride, oximo, hydrazino, methionyl, phosphoric acid, phosphonato, or a linear, chained, branched, or cyclic alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocycle, or acyl.

[0056] In another embodiment of the compound of formula I, the purine derivative comprises theobromine, which is a purine dione having the following chemical structure

Wherein, t₁、x、x₁Y and z are single bonds; wherein x is₂And t is a double bond; wherein w ', x', y ', z', x 'and y' are 1; wherein t' is 0; wherein R is₁And R₆Is hydrogen; wherein R is₂And R₄Is oxygen; wherein R is₃And R₅Is methyl.

[0057] In another embodiment of the compounds of formula I, the purine derivative comprises caffeine, which is a purine dione having the following chemical structure

Wherein, t₁、x、x₁Y and z are single bonds; wherein x is₂And t is a double bond; wherein w ', x', y ', z', x 'and y' are 1; wherein t' is 0; wherein R is₆Is hydrogen; wherein R is₂And R₄Is oxygen; wherein R is₁、R₃And R₅Is methyl.

[0058] In another embodiment of the compounds of formula I, the purine derivative comprises 1, 3 dimethylxanthine (theophylline), which is a purine dione having the following chemical structure

Wherein, t₁、x、x₁Y and z are single bonds; wherein x is₂And t is a double bond; wherein w ', x', y ', z', x 'and y' are 1; wherein t' is 0; wherein R is₅And R₆Is hydrogen; wherein R is₂And R₄Is oxygen; wherein R is₁And R₃Is methyl.

[0059] In another embodiment of the compounds of formula I, the purine derivative comprises a xanthine, which is a purine dione having the following chemical structure

Wherein, t₁、x、x₁Y and z are single bonds; wherein x is₂And t is a double bond; wherein w ', x', y ', z', x 'and y'Is 1; wherein t' is 0; wherein R is₁、R₃、R₅And R₆Is hydrogen; r₂And R₄Is oxygen.

[0060] In another embodiment of the compounds of formula I, the purine derivative comprises a compound having the chemical structure of formula III

Wherein, x and x₁Y, t and t₁Is a single bond; wherein x is₂And z is a double bond; wherein t ', w', x ', y', x 'and y' are 1; wherein z' is 0; wherein R is₂And R₄Independently of one another, are doubly bonded moieties containing oxygen, sulfur, CR₈R₉、SO₂Or NR₁₀(ii) a Wherein R is₁、R₃、R₆And R₇Independently of one another, comprises hydrogen, hydroxyl, amino, amido, alkylamino, arylamino, alkoxy, aryloxy, nitro, acyl, alkenyl, alkynyl, cyano, sulfo, sulfato, mercapto, imino, sulfonyl, sulfoxy, sulfinyl, sulfamoyl, phosphonyl, phosphinyl, phosphoryl, phosphinyl, thioester, thioether, anhydride, oximo, hydrazino, methionyl, phosphoric acid, phosphonato, or a linear, chained, branched, or cyclic alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocycle, or acyl.

[0061] In another embodiment of the compounds of formula I, the purine derivative comprises a compound having the chemical structure of formula IV

Wherein, x and x₁、y、t、t₁And z is a single bond; wherein x is₂Is a double bond; wherein t ', w ', x ', y ', z ', x ' and y ' are 1; wherein R is₂、R₄And R₆Independently of one another, are doubly bonded moieties containing oxygen, sulfur, CR₈R₉、SO₂Or NR₁₀(ii) a Wherein R is₁、R₃、R₅And R₇Independently of one another, comprises hydrogen, hydroxyl, amino, amido, alkylamino, arylamino, alkoxy, aryloxy, nitro, acyl, alkenyl, alkynyl, cyano, sulfo, sulfato, mercapto, imino, sulfonyl, sulfoxy, sulfinyl, sulfamoyl, phosphonyl, phosphinyl, phosphoryl, phosphinyl, thioester, thioether, anhydride, oximo, hydrazino, methionyl, phosphoric acid, phosphonato, or a linear, chained, branched, or cyclic alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocycle, or acyl.

[0062] In another embodiment of the compounds of formula I, the purine derivative comprises uric acid, which has the chemical structure

Wherein, x and x₁、y、t、t₁And z is a single bond; wherein x is₂Is a double bond; wherein t ', w ', x ', y ', z ', x ' and y ' are 1; wherein R is₁、R₃、R₅And R₇Is hydrogen; wherein R is₂、R₄And R₆Is oxygen.

[0063] In another embodiment of the compounds of formula I, the purine derivative comprises a compound having the chemical structure of formula V

Wherein, x and x₁、t₁And z is a single bond; wherein x is₂T and y are double bonds; wherein w ', x ', z ', x ' and y ' are 1; wherein y 'and t' are 0; wherein R is₄Is a double-bonded moiety comprising oxygen, sulfur, CR₈R₉、SO₂Or NR₁₀(ii) a Wherein R is₁、R₂、R₅And R₆Independently of one another, comprises hydrogen, hydroxyl, amino, amido, alkylamino, arylamino, alkoxy, aryloxy, nitro, acyl, alkenyl, alkynyl, cyano, sulfo, sulfato, mercapto, imino, sulfonyl, sulfoxy, sulfinyl, sulfamoyl, phosphonyl, phosphinyl, phosphoryl, phosphinyl, thioester, thioether, anhydride, oximo, hydrazino, methionyl, phosphoric acid, phosphonato, or a straight, chain, branched or cyclic alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocycle, or acyl.

[0064] In another embodiment of the compounds of formula I, the purine derivative comprises guanine, having the chemical structure

Wherein, x and x₁、t₁And z is a single bond; wherein x is₂T and y are double bonds; wherein w ', x ', z ', x ' and y ' are 1; wherein y 'and t' are 0; wherein R is₁、R₅And R₆Is hydrogen; wherein R is₂Is amino; wherein R is₄Is oxygen.

[0065] In another embodiment, the purine derivative comprises a compound having the chemical structure of formula VI

Wherein, x and x₂Y and z are double bonds; wherein x is₁T and t₁Is a single bond; wherein t ', w', x "and y" are 1; wherein x ', y ' and z ' are 0; wherein R is₂、R₄、R₆And R₇Comprising hydrogen, hydroxyl, amino, amido, alkylamino, arylamino, alkoxy, aryloxy, nitro, acyl, alkenyl, alkynyl, cyano, sulfo, sulfato (sulfato), mercapto, imino, sulfonyl, sulfenyl, sulfinyl, sulfamoyl, phosphonyl, phosphinyl, phosphoryl, phosphino, thioester, thioether, anhydride, oximo, hydrazino, methionyl, phosphoric acid, phosphonato, or a linear, chain, branched or cyclic alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocycle, or acyl group.

[0066] In another embodiment of the compounds of formula I, the purine derivative comprises adenine, which has the chemical structure

Wherein, x and x₂Y and z are double bonds; wherein x is₁T and t₁Is a single bond; wherein t ', w', x "and y" are 1; wherein x ', y ' and z ' are 0; wherein R is₂、R₆And R₇Is hydrogen; wherein R is₄Is an amino group.

[0067] In another embodiment of the compounds of formula I, the purine derivative comprises a compound having the chemical structure of formula VII

[0068]Wherein, x and x₂And t is a double bond; wherein, t₁、x₁Y and z are single bonds; wherein w ', y ', z ', x ' and y ' are 1; wherein t 'and x' are 0; wherein R is₂Is a double-bonded moiety comprising oxygen, sulfur, CR₈R₉、SO₂Or NR₁₀(ii) a Wherein R is₃、R₄、R₅And R₆Independently of one another, comprises hydrogen, hydroxyl, amino, amido, alkylamino, arylamino, alkoxy, aryloxy, nitro, acyl, alkenyl, alkynyl, cyano, sulfo, sulfato, mercapto, imino, sulfonyl, sulfoxy, sulfinyl, sulfamoyl, phosphonyl, phosphinyl, phosphoryl, phosphinyl, thioester, thioether, anhydride, oximo, hydrazino, methionyl, phosphoric acid, phosphonato, or a linear, chain, branched or cyclic alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocycle, or acyl.

[0069] In another embodiment of the compounds of formula I, the purine derivative comprises a compound having the chemical structure of formula VIII

[0070]Wherein x is₂Y and t are double bonds; wherein, x and x₁、t₁And z is a single bond; wherein w ', x ', z ', x ' and y ' are 1; wherein t 'and y' are 0; wherein R is₄Is a double-bonded moiety comprising oxygen, sulfur, CR₈R₉、SO₂Or NR₁₀(ii) a Wherein R is₁、R₂、R₅And R₆Independently of one another, contain hydrogen, hydroxyl, amino, amido, alkylamino, arylamino, alkoxy, aryloxy, nitro, acyl, alkenyl, alkynyl, cyano, sulfo, sulfato, mercapto, imino, sulfonyl, sulfoxy, sulfinylA group, sulfamoyl, phosphono, phosphinyl, phosphoryl, phosphino, thioester, thioether, anhydride, oximo, hydrazino, methionyl, phosphoric acid, phosphonate, or a linear, chain, branched, or cyclic alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocycle, or acyl group.

[0071] In another embodiment of the compounds of formula I, the purine derivative comprises 7-methylguanine, which has the chemical structure

[0072]Wherein x is₂Y and t are double bonds; wherein, x and x₁、t₁And z is a single bond; wherein w ', x ', z ', x ' and y ' are 1; wherein t 'and y' are 0; wherein R is₁And R₆Is hydrogen; wherein R is₂Is amino; wherein R is₄Is oxygen; wherein R is₅Is methyl.

[0073] In another embodiment of the compounds of formula I, the purine derivative comprises thioguanine, which has the chemical structure

[0074]Wherein x is₂Y and t are double bonds; wherein, x and x₁、t₁And z is a single bond; wherein w ', x ', z ', x ' and y ' are 1; wherein t 'and y' are 0; wherein R is₁、R₅And R₆Is hydrogen; wherein R is₂Is amino; wherein R is₄Is sulfur.

[0075] In another embodiment of the compounds of formula I, the purine derivative comprises a 6-mercaptopurine having the chemical structure

[0076]Wherein x is₂Y and t are double bonds; wherein, x and x₁、t₁And z is a single bond; wherein w ', x ', z ', x ' and y ' are 1; wherein t 'and y' are 0; wherein R is₁、R₂、R₅And R₆Is hydrogen; wherein R is₄Is sulfur.

[0077] In another embodiment of the compounds of formula I, the purine derivative comprises hypoxanthine, which has the chemical structure

[0078]Wherein x is₂Y and t are double bonds; wherein, x and x₁、t₁And z is a single bond; wherein w ', x ', z ', x ' and y ' are 1; wherein t 'and y' are 0; wherein R is₁、R₂、R₅And R₆Is hydrogen; wherein R is₄Is oxygen.

[0079] In another embodiment of the compounds of formula I, the purine derivative comprises a compound having the chemical structure of formula IX

[0080]Wherein x is₁、y、t₁And z is a double bond; wherein, x and x₂And t is a single bond; wherein w', x "and y" are 1; wherein t ', y ' and z ' are 0; wherein R is₁、R₂、R₄And R₆Independently of each other, contain hydrogenHydroxyl, amino, amide, alkylamino, arylamino, alkoxy, aryloxy, nitro, acyl, alkenyl, alkynyl, cyano, sulfo, sulfato (sulfato), mercapto, imino, sulfonyl, sulfoxy, sulfinyl, sulfamoyl, phosphonyl, phosphinyl, phosphoryl, phosphino, thioester, thioether, anhydride, oximino, hydrazino, methionyl, phosphoric acid, phosphonato, or a linear, chain, branched, or cyclic alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocycle, or acyl group.

[0081] In another embodiment of the compounds of formula I, the purine derivative comprises a 1H-purine, which has the chemical structure

[0082]Wherein x is₁、y、t₁And z is a double bond; wherein, x and x₂And t is a single bond; wherein w', x "and y" are 1; wherein t ', y ' and z ' are 0; wherein R is₁、R₂、R₄And R₆Is hydrogen.

[0083] In another embodiment of the compounds of formula I, the purine derivative comprises a diaminopurine having the chemical structure

[0084]Wherein x is₁、y、t₁And z is a double bond; wherein, x and x₂And t is a single bond; wherein w', x "and y" are 1; wherein t ', y ' and z ' are 0; wherein R is₁And R₆Is hydrogen; wherein R is₂And R₄Is an amino group.

[0085] It will be appreciated that the foregoing are merely examples of suitable low molecular weight additives and should not be construed as limiting their scope in any way.

[0086] As described above, the multilayer container can be used to make a container with enhanced gas barrier properties. These containers can be made by conventional methods, such as melt forming, to form the desired multilayer container from the polymer composition described above. Suitable melt forming methods include, but are not limited to, co-injection molding, co-extrusion, thermoforming, and die casting. A particularly preferred method of making the container to which the present invention relates is stretch blow molding. Such methods are well known to those skilled in the art and are described in U.S. patent nos. 6,596,213, 5,914,138, 5,011,720, and U.S. patent publication No. 2004/0247739. The disclosures of these documents are incorporated herein by reference in their entirety.

[0087] Methods of mixing low molecular weight additives into containers and polymer compositions are also provided herein. These methods are well known to those skilled in the art. For example, the additives may be injected directly into the composition matrix during injection molding, may be pre-mixed with the polymer resin prior to injection molding, or may be mixed with the polymer at a high concentration as a masterbatch and then mixed with the polymer resin prior to injection molding.

[0088] Fig. 5 illustrates a system 310 for preparing a rigid container preform 12 (see fig. 1) and fabricating a rigid container 14 (see fig. 2) from the preform in accordance with an embodiment of the present invention. As shown in fig. 5, PET 320 and low molecular weight additives 322, such as purine derivatives, are fed into a feeder or hopper 324, which feeder or hopper 324 delivers the components to a hot melt extruder 326 where the components are melted and mixed. The PET used to make the at least two outer layers is fed into a hot melt extruder 326 (not shown) in a similar manner. The hot melt extruder 326 coextrudes molten PET and a molten mixture of PET 320 and low molecular weight additives 322 to force fluid into the injection molding apparatus 328 along concentric annular flow paths to form the multilayer preform 12. The multilayer preform 12 is cooled and transferred from the injection molding apparatus 328 to the stretch blow molding apparatus 330, which stretch blow molds the multilayer preform 12 into the final rigid multilayer container 14.

[0089] The preform is produced with a melt residence time preferably less than 5 minutes, more preferably from about 1 to about 3 minutes. The melting temperature is preferably from about 270 ℃ to about 300 ℃, more preferably from about 270 ℃ to about 290 ℃. The melt residence time begins when the material enters the hot melt extruder 326 and begins to melt, and ends after the molten material is injected into the injection mold to form the preform 12.

[0090] In certain embodiments, the pressure at the mold cavity may be increased to improve the Injection Molding process to minimize plate out, as described in co-pending U.S. provisional patent application 60/825,844, filed by Schultheis, 2006, 9, 15, entitled "Pressurized Injection for Injection Molding and Method of Using," the disclosure of which is incorporated herein by reference in its entirety. The cavity pressurization alters the dynamics of the processing cycle by reducing or completely eliminating the ability of additives to diffuse through the copolymer and deposit on the interior surfaces of the mold. The desired pressure in the die cavity can be optimized for a particular polymeric material, polymeric matrix or additive.

[0091] The improved injection molding process (not shown) includes the additional step of increasing the mold pressure by introducing pressurized gas into the cavity of the mold, wherein the cavity determines the shape of the container preform; co-extruding a polymer composition into a die cavity; cooling the polymer composition to form a multi-layer container preform; the multilayer container preform is removed from the mold cavity.

[0092] The pressurized gas can be any gas that does not adversely affect the polymer composition. Non-limiting examples include air and its individual components, oxygen, nitrogen, and carbon dioxide; inert gases, argon, neon, helium and xenon; and mixtures thereof. In a particular embodiment, the die cavity is pressurized at a pressure ranging from about 1 to about 1000 psig.

[0093] The invention is further illustrated by the following examples, which are in no way to be construed as limiting the scope of protection. On the contrary, it is to be clearly understood that resort may be had to various other embodiments, modifications, and equivalents thereof which, after understanding the foregoing description, may suggest themselves to those skilled in the art without departing from the spirit of the present invention and/or the scope of the appended claims.

Examples

[0094] Commercially available polyester container grade resin (INVISTA, Spartanburg, SouthCholine) was dried in a vacuum oven at 140 ℃ overnight until the moisture level was below 50 ppm. The low molecular weight additive, caffeine, was dried overnight in a vacuum oven at 70 ℃ to remove surface moisture. The multilayer container was made with PET as the outer two layers and a composition of PET and caffeine as the barrier layer. The barrier layer comprises 20% by weight of the container. Caffeine makes up 15% of the barrier weight (3% of the container weight). A laboratory-scale Arburg single-cavity injection molding machine was used for injection molding. The preform was blow molded using a SidelSBO 2/3 blow molding machine to prepare an acceptable profile container. The 21.1g preform produced a 12 ounce (oz) container.

[0095]Subsequently, 22.2 ℃ 50% Relative Humidity (RH), N were measured using a Mocon 2/60 model instrument₂/H₂(99: 1) carbon dioxide transfer rate of the vessel at a contralateral air flow rate of 10 ml/min. The results are shown in Table 2. The Barrier Improvement Factor (BIF) is defined as the ratio of the carbon dioxide transfer rate of a multilayer polyester container having a low molecular weight additive in the barrier layer to the carbon dioxide transfer rate of a multilayer polyester container having no additive in the barrier layer.

TABLE 212 carbon dioxide transfer Rate for Multi-layer PET containers of ounces (oz)

Additive agent	Caffeine in Barrier layer (Wt%)	Barrier layer in container (Wt%)	Caffeine (Wt%)	Caffeine in blow molded container (Wt%)	CO2BIF
						N/A	0	20	0	0	1.00
Caffeine	15	20	3	3	1.3

[0096] The carbon dioxide BIF for the 12 ounce (oz) multilayer container was significantly improved after the caffeine addition to the PET composition of the barrier layer.

[0097] It should be apparent that the foregoing relates only to the preferred embodiments of the present invention and that numerous changes and modifications may be made herein without departing from the spirit and scope of the invention as defined by the following claims and the equivalents thereof.

Claims (25)

1. A multi-layered container comprising:

at least two outer layers comprising a polymer matrix; and

at least one barrier layer positioned between the at least two outer layers, wherein the at least one barrier layer comprises a first polymer composition comprising a polymer matrix and a low molecular weight additive.

2. The multilayer container of claim 1, further comprising at least one intermediate layer positioned between the at least one barrier layer and the at least two outer layers.

3. The multilayer container of claim 1, wherein

a) At least two outer layers comprising from about 99% to about 20% by weight of the multilayer container;

b) at least one barrier layer comprising from about 1% to about 80% by weight of the multilayer container;

c) the low molecular weight additive is present in the multilayer container in an amount ranging from about 0.2% to about 10% by weight of the multilayer container.

4. The multilayer container of claim 1, wherein the low molecular weight additive in the multilayer container is present in an amount ranging from about 0.2% to about 10% by weight of the multilayer container and the low molecular weight additive in the at least one barrier layer is present in an amount ranging from about 0.25% to about 25% by weight of the at least one barrier layer.

5. The multilayer container of claim 4 wherein

a) At least two outer layers comprising from about 99% to about 60% by weight of the multilayer container; and

b) the at least one barrier layer comprises from about 1% to about 40% by weight of the multilayer container.

6. The multilayer container of claim 1, wherein the low molecular weight additive in the multilayer container is present in an amount ranging from about 2% to about 10% by weight of the multilayer container and the low molecular weight additive in the at least one barrier layer is present in an amount ranging from about 3.75% to about 25% by weight of the at least one barrier layer.

7. The multilayer container of claim 6, wherein,

a) at least two outer layers comprising from about 99% to about 80% by weight of the multilayer container; and

b) the at least one barrier layer comprises from about 1% to about 20% by weight of the multilayer container.

8. The multilayer container of claim 1, wherein the low molecular weight additive in the multilayer container is present in an amount ranging from about 2% to about 5% by weight of the multilayer container and the low molecular weight additive in the at least one barrier layer is present in an amount ranging from about 3.75% to about 12.5% by weight of the at least one barrier layer.

9. The multilayer container of claim 8, wherein,

a) at least two outer layers comprising from about 99% to about 60% by weight of the multilayer container; and

b) the at least one barrier layer comprises from about 1% to about 40% by weight of the multilayer container.

10. The multilayer container of claim 1, wherein at least two of the outer layers comprise a thermoplastic polymer.

11. The multilayer container of claim 10, wherein the thermoplastic polymer comprises a polyester, a polyamide, a polyolefin, a polyimide, a polylactide, or a derivative thereof.

12. The multilayer container of claim 1, wherein at least two of the outer layers comprise polyethylene terephthalate.

13. The multilayer container of claim 1, wherein at least two outer layers comprise a poly (ethylene terephthalate) based copolymer having less than 20% diacid, or less than 10% glycol modification, or both, based on 100 mole percent diacid component and 100 mole percent diol component.

14. The multilayer container of claim 1, wherein at least two of the outer layers comprise polyethylene terephthalate containing recycled material.

15. The multilayer container of claim 1, wherein the polymer matrix of the first polymer composition comprises polyethylene terephthalate.

16. The multilayer container of claim 1, wherein the polymer matrix in the first polymer composition comprises a poly (ethylene terephthalate) -based copolymer containing less than 20% diacid, or less than 10% glycol modification, or both, based on 100 mole percent diacid component and 100 mole percent glycol component.

17. The multilayer container of claim 1, wherein the polymer matrix in the first polymer composition comprises polyethylene terephthalate containing recycled material.

18. The multilayer container of claim 1, wherein the low molecular weight additive comprises a compound having a molecular weight of less than 1000 daltons.

19. The multilayer container of claim 1, wherein the low molecular weight additive comprises a purine derivative.

20. The multilayer container of claim 19, wherein the purine derivative comprises a purine dione comprising caffeine, theophylline, theobromine, xanthine, uric acid, or a mixture thereof.

21. The multilayer container of claim 19, wherein the purine derivative comprises adenine, guanine, 7-methylguanine, thioguanine, 6-mercaptopurine, hypoxanthine, diaminopurine, 7H-purine, 1H-purine, or mixtures thereof.

22. The multilayer container of claim 1, wherein the low molecular weight additive comprises an ester, diester or polyester of aromatic or aliphatic nature; amides, diamides or polyamides of aromatic or aliphatic nature; cyclic esters having one or more ester groups; cyclic amides having one or more amide groups; or mixtures thereof.

23. The multilayer container of claim 2, wherein at least one intermediate layer comprises polyethylene terephthalate, polyethylene terephthalate containing recycled material, or an adhesive layer.

24. The multilayer container of claim 2, wherein at least one intermediate layer comprises the first polymer composition of at least one barrier layer.

25. A packaged beverage comprising a beverage contained in the multilayer container of claim 1 and a lid for sealing the beverage in the multilayer container.