MXPA06009464A - Using carbon dioxide regulators to extend the shelf life of plastic packaging - Google Patents

Abstract

A method for replenishing carbon dioxide gas in a carbonated beverage container where a carbon dioxide regulator releases carbon dioxide at a rate approximately equal to the rate of carbon dioxide loss from said container. Also disclosed is packaging system for maintaining a consistent pressure of a carbonated beverage comprising a closure, a plastic container, and a carbon dioxide regulator. Also disclosed is a method for making a packaging system for maintaining a consistent pressure in a carbonated beverage comprising overmolding a preform around an assembly for a carbon dioxide regulator, or blending a carbon dioxide regulator into the plastic material used to form the body of a container for said carbonated beverage. Also disclosed is carbon dioxide regulator composition for replenishing carbon dioxide gas in a carbonated beverage container comprising polymeric carbonates, organic carbonates, or materials that absorb and subsequently release carbon dioxide.

Description

REGULATORS USING CARBON DIOXIDE TO EXTEND THE LIFE OF STORAGE OF PLASTIC CONTAINERS Background of the Invention Plastic and metal containers have been replaced by glass in bottled beverages where easy handling, low weight and non-fragility are needed. Plastic containers, especially polyethylene terphthalate bottles, are widely used for the packaging of carbonated products such as beer, non-alcoholic beverages, still water and some dairy products. For each of these products there is some optimum amount of carbonation or carbon dioxide pressure (sometimes referred to herein as "C02") inside the container to maintain its optimum quality. In conventional plastic packaging, it is difficult to maintain the C02 pressure at its optimum level for a prolonged period of time. The plastic packaging is permeable to C02 and over time the pressure inside the bottle decreases. Finally, after a defined amount of carbonation is lost, the product is no longer suitable for use which is usually determined by a noticeable and unacceptable change in flavor and seasoning. The point at which this occurs generally defines the storage life of the container. The rate of loss of C02 is highly dependent on the weight and dimensions of the container and No. Ref .: 175114 temperature at which it is stored. Lighter, thinner bottles lose carbonation more easily, can not withstand high internal pressures, and have shorter storage life. When plastic bottles get smaller, the relative rate of carbonation loss becomes faster. Permeation is faster at higher temperatures, reducing storage life, and making it difficult to store carbonated beverages in plastic containers in hot climates and still maintain a reasonable storage life. Less expensive, lighter plastic bottles with longer storage life, and the ability to store bottles for longer in the absence of cooling have numerous economic advantages. A variety of approaches have been applied to the problems described above. A simple method to extend the storage life of a carbonated beverage is to add additional carbon dioxide at the filling point. This is currently used for carbonated soft drinks and for beer, but its effectiveness is inhibited due to the effect of over-carbonation on the quality of the product and the negative effects this can have on the physical performance of the bottle. Small differences in internal pressure within the container cause significant differences in the effervescent qualities of the drink. Dissolved C02 also affects the taste. These precise requirements vary from product to product. The over-carbonation is also inhibited by the pressure limitations of the container. It is possible to manufacture the most pressure resistant bottles but it requires the use of additional material in the construction of the bottle or more exotic plastics with higher yield. Carbonation can be maintained by reducing the permeation rate of C02. This typically involves the application of a secondary barrier coating to a PET bottle, the use of a less permeable polymer, more expensive than PET, the manufacture of multiple layer bottle constructions, or combinations of these methods. These manufacturing approaches are invariably significantly more expensive than what is incurred in the production of typical polyester bottles and often these create new problems especially with recycling. Materials that generate carbon dioxide have been used in the art to extend the shelf life of carbonated beverages. Molecular sieves treated with carbon dioxide for carbonated beverages have been used by the reaction of the combination of carbon dioxide with water. U.S. Patent No. 6,852,783 published by He al and U.S. Patent Application No. 2004/0242746 Al by Freedman et al. describe a composition of C0 release that can be incorporated or inserted into the packaging for carbonated beverages. The compositions in these references describe about twenty-five weight percent inorganic carbonate as the source of carbon dioxide mixed within the thermoplastic. A 32g PET bottle with a 25% load of sodium bicarbonate has the potential to release 4.5 grams of carbon dioxide. This is approximately ten times higher than that needed for application in a PET beer bottle and could similarly cause unsafe pressurization of the container. These structures also release their carbon dioxide too fast to regulate the pressure over a prolonged period especially if they were prepared in polyethylene terephthalate as opposed to polyethylene which has a lower permeation rate for moisture. We have found that such high load levels are inadequate for our application since they have the potential to release too much carbon dioxide into the container. SUMMARY OF THE INVENTION This invention is directed to a method for replenishing carbon dioxide gas in a carbonated beverage container. The method comprises inserting a carbon dioxide regulator into the beverage container or into a container closure device, and releasing carbon dioxide from the carbon dioxide regulator via a chemical reaction.- The release of carbon dioxide is regulated at a rate approximately equal to the rate of carbon dioxide loss from the container. This invention is also directed to a method for recharging carbon dioxide gas in a carbonated beverage container. The method comprises inserting a dioxide regulator into the container or into a container closure device; and subsequently regulating the release of carbon dioxide from the carbon dioxide regulator at a rate approximately equal to the rate of carbon dioxide loss from the container. This invention is also directed to a packaging system for maintaining a consistent pressure of a carbonated beverage comprising a closure device, a plastic container, and a carbon dioxide regulator. This invention is also directed to a method for manufacturing a packaging system for maintaining a pressure consisting of a carbonated beverage comprising overmolding a preform around an assembly for a carbon dioxide regulator. This invention is also directed to a method for manufacturing a packaging system to maintain a pressure consisting of a carbonated beverage comprising mixing a carbon dioxide regulator within the plastic material used to form the body of a container for the carbonated beverage. This invention is also directed to a carbon dioxide buffer composition for recharging carbon dioxide gas in a carbonated beverage container comprising polymeric carbonates and organic carbonates, individually, or in combinations thereof. This invention is also directed to a carbon dioxide regulator composition for recharging carbon dioxide gas in a carbonated beverage container comprising absorbing materials and subsequently releasing carbon dioxide. A "carbonated beverage" as used herein is an aqueous solution in which the carbon dioxide gas, in the range of about 2 to about 5 vol C02 / vol H20 for carbonated soft drinks, preferably about 3.3 to about 4.2 vol C02 / vol H20 for carbonated soft drinks, and approximately 2.7 to approximately 3.3 vol. C02 / vol H20 for beer, it has dissolved. "Carbon dioxide regulator", as used herein, is a composition that acts to maintain a more constant carbon dioxide pressure within a container over a period of time slowly releasing C02 through a controlled chemical reaction process or absorbing and desorbing C02 through a physical process where the rate of this release is approximately equivalent to the rate of loss of C02 of the container. Suitable C02 regulators include, polymeric carbonates, cyclic organic carbonates, organic carbonates such as alkyl carbonate, ethylene carbonate, propylene carbonate, polypropylene carbonate, vinyl carbonate, glycerin carbonate, carbonate - diethyl butylene-carbonate-, ethyl pyrocarbonate, methyl pyrocarbonate, dialkyl dicarbonate, or mixtures thereof; inorganic carbonates such as sodium bicarbonate, ferrous carbonate, calcium carbonate, lithium carbonate and mixtures thereof; molecular sieves, zeolites, activated carbon, silica gels and coordination polymers, organic metal structures ("MOF's"), and organic metal structures isorecticulares (IRMOF's). The amount of regulator 0 of C02 used depends on the amount of carbon dioxide released desired, which depends on the amount of carbon dioxide lost from the container during the storage life of the container The areas of the bottle in which the C02 regulator 5 can be placed include, but are not limited to, the device for closing the bottle, the mouth / neck of the bottle, the base of the bottle, or mixing it inside the plastic resin comprising the bottle. Brief Description of the Figures Figure 1 is an illustration of the effect of a carbon dioxide regulator on the performance of a PET beer bottle. Figure 2 is an illustration of the effect of a carbon dioxide regulator on the performance of a carbonated soft drink bottle. Figure 3 is an illustration of a carbon dioxide regulator-closure device with disk insert and cover. Figure 4 is an illustration of a carbon dioxide regulator assembly with disk and cover. Figure 5 is an illustration of a carbon dioxide regulator closure device with insert plug assembly. Figure 6 is an illustration of a carbon dioxide regulator mouth insert assembly. Figure 7 is an illustration of the production of carbon dioxide for an organic carbonate activated by water vapor. Figure 8 is an illustration of the effect of the tea bag material on the release rate of carbon dioxide . Figure 9 is an illustration of carbon dioxide loss on the internal pressure of the bottle. Figure 10 is an illustration of presaturation of carbon dioxide in 20 ounce bottles. Detailed Description of the Invention There is a wide variety of compositions that can serve as carbon dioxide regulators. These compositions fall into two categories. The first category are compositions that generate or release carbon dioxide via a controlled chemical reaction. Such compositions include: a) polymers such as aliphatic polyketones which generate carbon dioxide as a by-product of degradation of the polymer reaction with oxygen or organic and inorganic carbonate groups releasing carbon dioxide under hydrolysis, especially in the presence of acids . Catalysts, binders, and other additives can be combined with these materials to help control the carbon dioxide release process; and b) organic carbonates such as alkyl carbonates, ethylene carbonate, propylene carbonate, polypropylene carbonate, vinyl carbonate, glycerin carbonate, butylene carbonate, diethyl carbonate, ethyl carbonate, ethyl pyrocarbonate, methyl pyrocarbonate, cyclic carbonate acrylates such as carbonate acrylate of propane trimethylol, and dialkyl dicarbonates which generate carbon dioxide under hydrolysis which can be increased by reaction with an acid such as citric acid or phosphoric acid. The second category are sorbent compositions that store carbon dioxide and then release it into the container when the carbon dioxide is lost from the container. These include: absorbents such as silica gel; molecular sieves, 'zeolites, clays, activated alumina, activated carbon, and coordination polymers, organic metal structures or "MOF's" and metal-organic structures isoreqt.icular.es ._ or _ "IRMOF's" which are crystalline oxide materials of metal and organic acids analogous to zeolites. These materials can be modified to have variable pore sizes and carbon dioxide storage capacity. The various carbon dioxide generators described above can be mixed within the polymer that builds the container or closure device. These may also exist as layers in a multi-layer closure device, cover, or bottle design. Alternatively, these can be molded into an insert or disc that can be placed on top of the bottle closure device or on an insert which could be placed within the mouth area of the container.

Some designs are shown in Figures 3-6. In systems where moisture is used to regulate the release rate of C02, the carbon dioxide regulator can be encapsulated or mixed with an appropriate polymer selected for its moisture permeability and C02. For proper selection of polymer encapsulation or barrier, the moisture permeation rate can be used to control the velocity of C02 released and equalize the C02 loss rate of the package thereby achieving a package which maintains a constant C02 pressure. internal for a period of time. This period of time is referred to as the regulation period. In systems where oxygen is used to regulate the release rate of C02, the carbon dioxide regulator can be encapsulated or mixed within an appropriate polymer selected for its oxygen and C02 permeability. Again, by proper selection, the CO02 generation rate can be regulated to equal the C02 loss ratio of the package and maintain an almost constant internal pressure of C02 for a period of time. When the carbon dioxide regulator is prepared from a C02 absorbent material, the additional C02 necessary to extend the storage life can be incorporated through over-carbonation at the filling point. The container can be over-carbonated with the precise amount of C02 needed based on the desired increase in storage life, regulation period, and the C02 permeability of the container. The C02 regulating material must rapidly absorb this excess of C02 before the package can deform due to the excess of C02. This absorbance should occur within about six hours and preferably in about one hour. The C02 regulator should then release the carbon dioxide absorbed at a rate less than or preferably approximately equivalent to the rate of carbon dioxide loss of the container itself. This will ensure that a uniform and stable internal C02 pressure is maintained. The performance of specific regulator compositions can be optimized by proper drying, impregnation and manufacturing conditions that are well known to those skilled in the art. It is preferred to minimize the volume of the carbon dioxide regulator such that the space of the container is used efficiently. Alternatively, the carbon dioxide regulator can be pre-charged with C02 by subjecting it to a C02 gas environment such that it absorbs and maintains enough C02 gas to replace the C02 lost from the container during normal use of the container. The carbon dioxide regulator can be incorporated into the package in any number of ways These include, but are not limited to, placing it inside the closure device in a small cup or as a manufactured disc. These are illustrated in Figures 3-5. These designs have various components, the body of the closure device, the carbon dioxide regulating material, and a cover material or cup which supports the carbon dioxide regulator and can separate it from the contents of the container. The cover material can be designed to help control the rate of C02 loss of the carbon dioxide regulating material either by acting to control the carbon dioxide. C02 permeation rate directly or by controlling the rate at which an activator can reach the carbon dioxide regulator. Water and water vapor can act as an activator in many systems. The amount of the carbon dioxide regulator may vary depending on the requirements of the container. For smaller increments in storage life a thin insert can be placed inside the closure device. For larger effects, where more carbon dioxide regulator might be required, the cup or plug-closure design could allow large amounts of the carbon dioxide regulator to be used. The carbon dioxide regulator can be placed inside the bottle after it is manufactured by placing a piece formed in an appropriate position in the bottle. This is illustrated in Figure 6. One approach could be a short tubular piece placed within a molded slot within the mouth area of the bottle either during or after liquid pressure molding. Another approach could be to over-mold a bottle preform around a carbon dioxide regulator assembly by placing the assembly on the center pin of a mold by conventional injection and then overmolding a preform around this assembly using such a polymer. as PET. The preform containing the carbon dioxide regulator assembly could then be blown into a bottle using conventional equipment. Another concept could be to use the tie rod to place a regulator assembly inside the bottle during liquid pressure molding. The carbon dioxide regulator can also be mixed into the plastics used to form the container body or housing. The preform containing the carbon dioxide regulator assembly could then be blown into a bottle using conventional equipment. For such a system, it could be advantageous if the carbon dioxide regulator can not become active until the container is filled. The carbon dioxide regulator can also be added as a layer in a multiple layer manufacturing either as a layer in the bottle, a layer in the closure device, or a layer in the cover. This layer can be manufactured by any conventional multiple layer extrusion and manufacturing practices common in the industry including manufacture of multiple layer preform, multiple layer film extrusion, coating, and lamination. The number of layers in the final package form can be from two to ten layers, and preferably three to five layers. The rate of carbonation release from the carbon dioxide regulator can be controlled by rolling with a film, coating the assembly of the carbon dioxide regulator, or mixing the carbon dioxide regulator within another material, especially a plastic. This can also facilitate the manufacture of the carbon dioxide regulator in a form suitable for its "" application. One approach could include mixing the carbon dioxide buffer material in the polymer used to form the cover of the closure device or mixing the carbon dioxide buffer material within the material used to produce the closure device itself. Molecular sieves are a preferred carbon dioxide regulator for this invention. Uncompacted, clean molecular sieves have the ability to absorb high C02 levels. The 13X molecular sieves absorb approximately 18% of their weight of CO2 at the bottle pressure. Thus, for a 0.35 liter (12 oz) carbonated soft drink bottle that is carbonated to 4.0 vol., Approximately 0.525 g of C02 gas is required to replace the C02 that is lost from the container and doubles the storage life. Suitable molecular sieves for acting as carbon dioxide regulators include, but are not limited to, aluminosilicate materials commonly known as 13X, 3A, 4A, and 5A sieves, faujasite, and borosilicate sieves. These materials can _ modified by_ ion exchange processes to modify their physical properties, and may be combined with fillers, binders, and other processing aids. Another set of carbon dioxide regulators are coordination polymers, organic metal structures ("MOF's"), and metal-organic isorecticular structures (IRMOF's). These are polymer structures manufactured by the reaction of metal and organometallic reagents with. organic spacer molecules such that a porous open structure results. Any of the several related high porosity network structure systems prepared through such a reaction and capable of absorbing and releasing carbon dioxide should be included. Another set of carbon dioxide regulators they include organic and inorganic carbonates. These materials react with water to form carbon dioxide especially in the presence of acid catalysts. Mixing these materials into PET and activating them by filling the container with an acidic beverage is a preferred embodiment of our invention. Suitable inorganic carbonates could include sodium bicarbonate, calcium carbonate, and ferrous carbonate. Suitable polymeric carbonates could include cyclic carbonate copolymers such as poly (vinyl alcohol) cyclic carbonate and polycyclic carbonate acrylate or linear aliphatic carbonate polymers. The poly (vinyl alcohol) cyclic carbonate is formed by the catalyzed reaction of polyvinyl alcohol with diethyl carbonate. A polycyclic carbonate acrylate can be made by polymerizing the monomer, trimethylol propane carbonate acrylate, which is made from the catalyzed reaction between 2-ethyl-2- (hydroxylmethyl) -1,3-propanediol (trimethylpropane) and diethyl carbonate. Another set of carbon dioxide regulators are polymers that oxidize to form carbon dioxide. An example of this could be aliphatic polyketones, examples could include polymers made by the reaction of ethylene and / or propylene with carbon monoxide. One of the important parameters for optimizing the present invention is to maximize the density of C02 in the source of C02. The higher the density of the source with respect to moles of C02 per unit volume, the more C02 can be incorporated into the container to extend the storage life, while at the same time minimizing the volume occupied by the source. A variety of materials and their C02 densities are shown in Table 1 below. TABLE 1 Density of Carbon Dioxide Sources Another challenge is to regulate the release of C02 from the source such that this generally corresponds to the rate of loss of C02 from the container. The release of C02 can be optimized through the selection of the source itself, controlling the activation of the release reaction of the C02 or by appropriate selection of the membranes, coatings or films separating the C02 source from the beverage. Several methods are explained in the Example section below. Another important parameter to optimize the present invention is the volume, or thickness, of the carbon dioxide regulator required to produce sufficient amounts of C02. To calculate the insertion of the carbon dioxide regulator or thickness for a variety of reactive materials, a series of calculations are made assuming 100% conversion of reactive carbonate to C02. in the case of di- or tri- functional organic acids, one or more of the acid groups may react, but for purposes of the calculations in the table below, it is assumed that only one acid group reacts. CaCO3 and fumaric acid combination is included to demonstrate the effect of a denser reactive pair (higher yield of C02 by volume). Finally, ethylene carbonate is shown as an example of an organic carbonate source, which decomposes upon reaction with water and does not require acidification. Table 2 below shows the effect of reagents on the thickness of the insert.

TABLE 2 Effect of Reagents on Thickness of Insertion Reagent Type Bottle Cale. Thickness Ins. 0. 35 lt CSD 1 mol NaHC03 + 1 mol Acid 0.734 cm (12 oz.) Citrus (0.2889") 0. 35 lt CSD 1 mol CaC03 + 1 mol Acid 0.407 cm (12 oz.) Fumaric (0.1602") 0. 35 It Beer 1 mole NaHC03 + 1 mole Acid 0.228 cm (12 oz.) Citrus (0.1134") 0. 35 liter Beer 1 mol CaC03 + 1 mol Acid 0.16 cm (12 oz.) Fumaric (0.0628") 0. 35 lt Ethylene Carbonate Beer 0.107 cm (12 oz.) (0.0423" 0. 47 It Beer 1 mole NaHC03 + 1 mole Acid 0.193 cm (16 oz.) Citrus (0.0758") 0. 47 lt Beer 1 mol CaC03 + 1 mol Acid 0.107 cm (16 oz.) Fumaric (0.0420") 0. 47 lt Ethylene Carbonate Beer 0.072 (16 oz.) (0.0283") In the above table, mono-ionization is assumed and the total volume of the insert or disc is also increased by the addition of a non-reactive binder.

Some carbon dioxide regulators can be precharged with C02 by subjecting them to a C02 gas environment such that it absorbs and maintains enough C02 gas to replace the loss of C02 from the container during normal use of the container. Preferably, C02 is released from the carbon dioxide regulator at a rate approximately equal to the rate of permeation loss of C02 from the container. One method of loading the carbon dioxide regulator with C02 is to place a disk or insertion of the composition of the carbon dioxide regulator within the closure or termination device of a carbonated beverage bottle and then over-pressurizing the bottle with a quantity of CO2 gas which is necessary to extend the storage life of the container to the desired objective. The excess C02 is then rapidly absorbed by the carbon dioxide regulator such that the bottle is not excessively stressed. The absorbed C02 is then released into the headspace of the carbonated beverage when the vapor pressure of C02 decreases when the C02 product is lost from the container. Another method is to pre-load the disc or insert the carbon dioxide regulator with C02 and place the pre-loaded disc inside the closure device or mouth during the bottling and / corking process. Examples 1 Several carbon dioxide regulators, specifically organic carbonates, were tested to determine whether they could be activated by steam alone and without organic acid present. The results shown in Figure 7 illustrate that water vapor activates the production of C02 from organic carbonates by hydrolysis and an organic acid is not necessary. Example 2 A variety of cover materials were tested to determine the effect of the permeability of the roofing material on the production speed of C02. A mixture of sodium bicarbonate and citric acid was sealed in a pouch suspended over 25 mL of water in a sealed bottle. The pouches were made from three different materials with different permeabilities to moisture: a paper tea bag, polylactic acid and polyethylene. The results in Fig. 8 show that a very low moisture barrier allows the fastest speed of CO 2 generation and the highest moisture barrier provided by the polyethylene provides the lowest speed. Thus, a moisture barrier material between the composition of the carbon dioxide regulator and the carbonated beverage can be used to control the production rate of C02. Example 3 C02 Absorbent Saturation and Release Several carbon dioxide generators, particularly absorbent materials, were tested to determine their ability to store and release C02 under high pressure and to thereby extend the storage life of a carbonated beverage. The selected absorbent materials were first saturated under a high pressure C02 environment. The absorbent materials were then placed inside bottles of (20 oz) 0.59 liters and the bottles were quickly carbonated with dry ice and capped. The molecular sieves were obtained from commercial sources and used as received or dried by heating under vacuum. The 13X molecular sieve discussed below was obtained from Aldrich Chemical Company and used as received or dried under vacuum prior to use. The speed of loss of C02 of the bottles was recorded in the course of time. The results are shown in Table 3: TABLE 3 Summary of C02 Saturation Experiments Sample Improvement% Storage Life Bottles "Control (additives no - 'saturated' Bottles saturated film p / 8416 32.6% Bottles Molecular sieves for 4A 104.2% Bottles Molecular sieves for 3X 61.4% Bottles pre-saturated @ 300 psig C02 0.2% The results showed that the shelf life of a drink Carbonated can be extended by placing articles saturated with C0 inside the bottles and that the molecular sieves are particularly effective regulators. Experiment 4 - Over-pressurized bottles with molecular sieves with C02 An experiment was conducted to test the concept of over-pressurizing the bottle, by storing excess C02 in the molecular sieves and releasing the C02 absorbed from return inside the head space of the bottle. Four sets of 0.35 liter (12 oz.) Bottles, each containing 15 cc of water and carbonated with dry ice, were tested. The first set was a control and was loaded with 4.0 volumes of C02 only. The second set was loaded with 4.75 volumes of C02 and about 3 grams of finely ground 13X molecular sieves dried under vacuum and contained in a test tube were also enclosed within the bottle. The third set was loaded with 4.75 volumes of C02 and about 3 grams of finely ground 13X molecular sieves also contained in a test tube were enclosed within the bottle. The results shown in Figure 9 show that the control bottles lost C02 at a normal speed. However, the two sets containing the molecular sieves showed an initial rapid fall in pressure of C02 indicating that C02 was absorbed by the molecular sieves. The C02 level in the headspace of the bottles then increased due to the molecular sieves emitting the C02 back into the bottle. These two sets showed a theoretical increase of 11 weeks in storage life when compared to the control. For the following examples, PET bottles were manufactured using blow molding methods. conventional injection. These were made from a conventional PET bottle resin. The bottles for carbonated soft drink (CSD) weighed 26.5 grams and had a volume of 0.35 lt (12 ounces). The beer bottles used in the following examples had a weight of 37 grams, a volume of 500 mL, a champagne base, a mouth 1716, which is the neck and mouth of the bottle and use a conventional CSD closure device. The effect of carbon dioxide regulators on the internal pressure of PET bottles was directed by placing a heavy amount of the regulator sample into a test tube and placing it inside the PET bottle. Ten milliliters of water was added to the bottle in such a way that only water vapor was in contact with the absorbent. The bottles were then carbonated in accordance with the method taught in U.S. Patent No. 5,473,161. All test bottles were evaluated in triplicate. The amount of carbon dioxide in the bottle was measured by FT-IR in accordance with the method described in U.S. Patent No. 5,473,161 under license from The Coca-Cola Company. This corresponds directly to the internal pressure of C02 in the bottles. The measurements were made periodically to track the amount of C02 that remains in the container. A conversion factor was used to the signal to convert the FT-IR result to C02 volumes, a commonly used terminology in the packaging industry when describing the amount of carbonation in a beverage. A volume of C02 is the amount needed to provide an atmosphere of pressure to the container at 20SC. The conversion constant was determined by placing a known quantity of C02 inside a bottle and measuring the level of C02 within one hour of sealing. The conversion constant was determined at various pressures and found to be constant within the accuracy of the test. The storage life was determined by the amount of time it takes the pressure of C02 in the package to fall to a minimum acceptable value. The requirement varies depending on the packaged product. For carbonated soft drinks, an initial carbonation level of approximately 4.0 volumes is used within a minimum acceptable level of approximately 3.3-3.4 volumes. This is a loss of 15-17.5%. For beer, a minimum level of carbonation is typically 2.7 volumes with an initial level of 3.0 volumes. The initial carbonation level was determined for each test by measuring the level of C02 inside the container shortly after sealing. In cases where the storage life was reached when our experiment ended, the value was determined by extrapolation as shown in Figures 1 and 2. Most of the Packaging is properly used before its last life storage is reached. Maintaining a very consistent carbonation level when most of the containers will be used is important for the quality of the product. The period during which the internal C02 pressure remains relatively constant is defined as the period of regulation. This is illustrated in Figures 1 and 2. Comparative Example 5 A PET beer bottle with a mouth 1716 and CSD closure device was carbonated to a level of 3.3 volumes of C02. This is an initial carbonation level slightly higher than that of the typical industry. In beer, storage life is reached when the carbonation level reaches volumes of 2.7. The storage life and rate of loss of C02 are shown in Table 4 and Figure 2. Comparative Example 6 A CSD bottle of 0.35 liters (12 ounces) with a. Closing device CSD was carbonated to a level of 4.0 volumes of C0. For soft drinks storage life was reached at 3.3 - 3.4 volumes of C0. The results are shown in Table 4.

Example 5: Effect of 13X sieves on the life of PET beer bottle storage One gram of dry 13X molecular sieve powder was placed in the test tube within the same PET bottle-closure combination used in Comparative Example 5 C02 was added such that a carbonation level of 3.6 volumes of C02 could result in the absence of the absorber. The results are shown in Figure 1 and Table 4. Carbonation was monitored until the minimum requirement for beer, 2.7 volumes of C02 were reached. Placing the absorbent within the container resulted in an intermediate reduction of the C02 measured inside the bottle and the shelf life of the container extended for 36 days longer than that of Comparative Example 5. Example 6: Effect of 13X molecular sieves on the life of the container. CSD bottle storage of 0.35 liters (12 ounces) This experiment was carried out as in Example 5 except that a CSD bottle of 0.35 liters (12 ounces) and CSD closure device was used. One gram of molecular sieve dry powder was placed in a test tube inside the same PET bottle. C02 was added such that a carbonation level of 4.35 volumes could result in the absence of the absorber. The level of carbonation was monitored over time. The results are shown in Figure 2 and Table 4. Place the absorbent inside the container resulted in an immediate reduction of free C02 and the shelf life of the container was extended by 42 days when compared to Comparative Example 6. TABLE 4 Effect of Absorbent on Storage Life and Loss of Internal Pressure of C02 Comparison of Various Molecular Sieves A variety of molecular sieves (shown as individual letters in the tables below) were tested in accordance with the procedure described above using one gram of molecular sieve. These materials were obtained from several manufacturers (shown as "Mfr" in the Tables below) and used as received. One gram for each of the materials was tested in CSD 0.35-liter (twelve-ounce) bottles with PCO mouth (plastic closure device only) in an aggregate carbon dioxide volume of 4.5 volumes of carbon dioxide. The initial carbon dioxide pressure was measured one hour after filling. The data on these screens Molecular sieves are shown in Table 5. TABLE 5 Life Extension of Storage with Various Molecular Sieves The effect of the drying temperature on the carbon dioxide retention performance was also measured. Drying the molecular sieves also increases their absorption capacity. The sieves were dried at 120 ° C for 15.5 hours and tested as described above. The results are shown in Table 6.

TABLE 6 Performance of Molecular Sieves After Drying at 120-C The sieves were dried at 240 aC and tested as described above. The results are given in Table 7. TABLE 7 Effect of Sieve Drying at 2402C Effect of Surface Area on Performance A sample of 13X sieve powder was milled using a Spex Mili crusher to decrease the size of particle and increase its surface area. The surface area and particle size of the Aldrich 13X screens before and after grinding are shown in Table 8. TABLE 8 Surface Area and Particle Size of Aldrich 13X Sieves Before and After Grinding.

The performance of these materials was tested as described above using a 12-oz CSD bottle with a PCO mouth and one gram of sieve. The results are shown in Table 9. TABLE 9 Effect of Surface Area of Molecular Sifers on Carbonation Retention Effect of Molecular Sieves in Tablet Form Molecular sieves were compressed into tablets and tested by exposing the tablet to the vapor space of the bottle or by immersing the tablet in water in the container. The results are shown in Table 10. TABLE 10 Comparison of Tablets and Molecular Sieve Powder Effect of Coatings to Modify the Performance of Sieve Tablets Molecular sieve tablets were prepared by compression and drying at 125 aC. These were coated with a 2% solution of General Electric Silicone RTV615A 01P by mixing 10 parts of elastomer with 1 part of curing agent, in heptane. The tablets were immersed in the coating and allowed to air dry at room temperature. The covered and uncovered tablets were placed in the head space of a 0.35 liter (twelve ounce) CSD bottle and tested as described above, and the results are shown in Table 11.

TABLE 11 Effect of Silicon Coating on Tablet Performance Effect of Molecular Sieves on Inserts in the Closing Device A small insert was prepared by injection molding by molding a cup which could be fitted within the closure device and also act as the cover of the sealing mechanism. This cup was designed to contain lg of molecular sieve material and fit inside the mouth of a twelve-ounce CSD bottle. These cups were injection molded from polyethylene and polypropylene and the carbonation retention performance of molecular sieves placed within these cups was tested as described above. The data is shown in Table 12. TABLE 12 Effect of Placement of Molecular Smears in Closing Device Inserts Note: 70-7931 is polypropylene obtained from BP 9551 low density polyethylene obtained from Dow Chemical Comparison of Molecular Sieve with Ascarite The performance of 13X molecular sieves and Ascarite, a mineral absorbing carbon dioxide, was compared as described above using lg of each material. The results are shown in Table 13.

TABLE 13 Comparison of Carbonation Retention of Molecular and Ascaritated Sieve Acid Activated Regulator Systems A convenient method to regulate the release of C02 could be through contact of the container with the beverage. Many carbonated soft drinks are quite acidic, thus making acidity a convenient trigger for release of C02 from a carbon dioxide regulator incorporated within a PET bottle or closure device. Common acids found in beverages include phosphoric acid and citric acid. Carbon dioxide regulators for this concept could include inorganic carbonates such as calcium carbonate, organic carbonate oligomers and polymers, such as those shown in Table 14, combinations thereof. The inorganic carbonates and organic carbonate oligomers were obtained from Aldrich Chemical Company. The cyclic carbonate polymers are obtained from Prof. Motón H. Litt from the Department of Macromolecular Science and Engineering at Case Western Reserve University. PET was mixed dry with several sources of carbon dioxide and combined in an APV laboratory scale double screw extruder to form a warm water thread. Approximately three grams of material were placed in a pH 2 solution of phosphoric acid in a jar with a 155 ml headspace and sealed with a wrinkled top silicone gasket. The generation of carbon dioxide was monitored by GC. The carbon dioxide values generated per gram of the regulating material per day are shown in Table 14. The approximate amount of the regulator required to equalize the release rate of C02 for a 0.35 ml carbonated soft drink container. (12 ounces) is also indicated. TABLE 14 C02 release rate of PET mixtures Pressurization Effect 4A extruded pellet tablets with PET as a binder were prepared and saturated. 11.3 grams of 4A sieve were used with 4.8 grams of PET. The two materials were mixed together, and molded in a compact cylinder at a compression pressure at 10000 psig and approximately 100 to 1202C. The tablets were saturated at C02 at room temperature and 300 psig for 36 hours. The tablets absorbed 1.47 grams of CO2 on average. The tablets had been cut in half to allow them to be placed inside the bottles. The bottles (6) were closed and monitored. Figure 10 shows that the storage life was extended with the presaturated material 4A. A maximum at the level of C02 in the bottle that occurred partially through the test reveals the slow process of evolution of C02 from material 4A. 'The 13X tablets were prepared by a similar process. 3.2 grams of crushed 13X (Aldrich as for the 4A) and 4.8 grams of PET were molded into tablets, cut in half and saturated with C02 at room temperature, 300 psig for 36 hours. The saturated pellets were placed in PET bottles and the C02 levels were monitored. The storage life was extended by the additional C02. The tablets had absorbed 0.52 grams of C02 on average. The PET film, 33.87 square cm (5.25 square inches), 10 mil thick, and not expanded, was saturated at room temperature and 300 psig for 36 hours. 29 grams of film were assigned to each bottle. The PET film was saturated with C02 at room temperature for 36 hours at 300 psig. The film absorbed 0.99 grams of C02 on average. The film was placed in PET bottles (6) and the internal level of C02 was monitored. The C02 that was developed from the PET film extended the storage life as shown in Figure 10. Additional Discussion of Examples 5 and 6 The placement of an appropriate absorbent within a PET bottle of carbonated beverage allows additional C02 to be added. without causing an increase in the internal pressure of the bottle. This is easily observed for Examples 5 and 6. For Example 5, C02 was added to create a carbonation level of 3.6 volumes but after sealing only 3.38 volumes was measured. In Example 6, 4.35 Volumes were added but only 3.89 volumes were measured within one hour after sealing. In each case, C02 was rapidly absorbed, preventing over-carbonation from affecting the bottle. The absorbed C02 was then released into the bottle slowly over time resulting in a much more constant C02 pressure inside the container. The regulation period was thirty-thirty-four days for examples 5 and 6 respectively. This is adequate within the period of time during which most high volume carbonated beverages are packaged and sold. ._. ... The last storage life for the examples and 6 is significantly longer than that observed in the comparative examples. The storage life was extended for thirty days in each case. A variety of different molecular sieves were evaluated as a basis for a carbon dioxide regulator. As illustrated in Table 5, we find that a wide variety of materials are effective. We examined the effect of the drying temperature on the performance of the carbon dioxide regulator. We found that it was not necessary to dry the molecular sieve-based regulators to achieve excellent performance and to dry them at a lower temperature than conventionally used to dry these materials, 120 2C, it provides some improvement in performance. Drying at a higher temperature, 240 ° C, resulted in a significant decrease in the regulation period. Avoiding the need to dry the screens prior to use could be advantageous in a number of carbon dioxide regulator designs. Increasing the particle size and surface area of the absorber resulted in a significant increase in the amount of C0 that a carbon dioxide regulator could absorb as shown in Table 5. Optimize the particle size and surface area for a Particular carbon dioxide regulator could be a matter of routine experimentation. The physical form of the regulator will be important in the development of an optimized carbon dioxide regulator design. We found that molecular sieves compressed in the form of a tablet could be just as effective as a regulator as well as molecular sieve powder. The optimization of the figure and shape of the regulator is once again a matter of routine experimentation. Coating a molecular sieve tablet is expected to be a particularly effective method to produce a regulator. A critical feature of this coating could be to allow the rapid absorption of C02 during filling of the bottle to facilitate over-pressurization as a method to introduce additional carbon dioxide. We find that the silicone coatings are effective as shown in Table 11. An insert cup assembly represents a practical method for producing a carbon dioxide regulator system. We found that polyethylene based on insert cups could be effective as illustrated in Table 12. Other polyolefins suitable for such assemblies could include thermoplastic polyolefin elastomers, ethylene copolymers, such as linear low density polyethylene, and ultra low polyethylene. density, ethylene-propylene copolymers, propylene copolymers, and styrene thermoplastic elastomers. Softer polyolefin materials capable of forming an airtight seal with the surface of the container could be preferred. Determining the optimized and material dimensions for an insert cup or other form of regulator is a matter of routine experimentation. Many materials which absorb carbon dioxide do not easily form regulatory systems as illustrated in Table 13. Ascarite is a mineral which readily absorbs large amounts of carbon dioxide but not in its pure form produces an appropriate carbon dioxide regulator. that C02 is not released at a speed similar to the speed of loss of C02 from the container. There are a number of factors that a person skilled in the art understands that could improve this invention. It is advantageous that the absorbers have a capacity to absorb carbon dioxide as high as possible. The capacity is the weight of the carbon dioxide absorbed by the weight of the absorbent. Absorbents with higher C02 absorption capacity could be preferred since it might be necessary to add less to the package to generate the improvement in the desired storage life. The conditions under which they are manipulated are also important. It is well known that heating molecular sieves can extract trapped species and create more capacity. Surprisingly, over-drying deteriorates the performance of these materials as a C02 regulator. The molecular sieve may need to be combined with a binder material to facilitate its manufacture in appropriate parts for its application. The guy in need. it should depend on the properties of the screen and the final properties required in the final manufactured part. These could include inorganic binders regularly used to improve the mechanical properties of molecular sieves, organic polymers in which the absorbent can be mixed and molecular weight resins lower and oligomers in which the absorbent could be dispersed. These may be thermosetting or thermoplastic in nature and may include materials such as silicone rubbers, polyolefins, epoxies, unsaturated polyesters, and polyester oligomers. It is important to control the rate at which the absorbed CO2 is released from the absorbent and to prevent liquid water from causing a sudden release of C02, to avoid extracting sensory components from the beverage, or to allow the components of the container to make contact with the liquid. regulator in a controlled manner. This can be done by placing the absorbent within a polymer with a low permeability for water or placing a thin film of such a polymer between the beverage and the absorbent material. This material may need to allow C02 to readily absorb over-carbonation and could be comprised of a semi-permeable membrane, a permeable membrane or a material with high permeability to C02 and its combinations. Suitable materials include polyolefins such as low density polyethylene, high density polyethylene, polypropylene, ethylene-propylene elastomers, ethylene-vinyl acetate copolymers, and silicone rubbers. Suitable membrane materials could include liquid impervious / vapor permeable materials such as Core-Tex or similar structures. The Especially preferred embodiments of our invention mix the absorbent the absorbent within an appropriate polymer and use this to manufacture the closure device of the bottle, inserting a manufactured absorbent disc into the closure device behind the cover of the closure device, protecting a tubular insert with a thin film or polymer coating permeable to C02 or by molding a tubular insert from a combination of absorbent and polymer permeable to C02. The preferred method of placing the absorber inside the bottle and optimizing its performance is a matter of further experimentation ... Carbon dioxide regulators can also be formed by mixing C02 releasing materials into the PET as shown in Table 14. For carbon dioxide regulator, it is critical that the release of C02 does not occur prior to filling the container such that the performance of the carbon dioxide regulator is not lost in the storage of the bottle. A variety of inorganic and organic carbonates can be blended into PET at a concentration below 20% by weight and preferably below 10% by weight and achieve a release rate of C02 equivalent to the rate of loss of C02 of a conventional PET container. . These are activated by exposing them to water with a pH range similar to many carbonated soft drinks. One aspect of this invention is to allow carbonated beverages to be stored for longer periods in hot locations without the need for more expensive coatings or cold storage conditions. In hot locations, the storage temperature can be quite high and since the permeability of the bottles to carbon dioxide is proportional to the temperature, the loss rates of C02 are higher. Also, due to these temperatures the internal pressure inside the bottle can reach dangerous levels. Thus, a system which can maintain a stable and consistent internal pressure and increase the storage life is particularly advantageous. Another aspect of this invention is to allow light weight of the carbonated beverage bottles and maintain their current storage life. The permeation rate of a container is inversely proportional to the thickness of the container wall. It is economically advantageous to make the packaging as light in weight as possible which results in reducing the thickness of the walls. A system which extends the shelf life of conventional packaging will be able to provide the thinner wall packaging with a storage life equivalent to that of conventional packaging. Many of the bottles in applications to that this technology is targeted are containers that can not be light in weight, without additional loss in storage life or through the use of more expensive bottle making techniques. Another aspect of this invention is to allow the maintenance of an optimum and stable carbonation level for longer periods of time producing a product with more consistent flavor and quality. The amount of carbon dioxide dissolved in a beverage is proportional to the carbon dioxide pressure in the container. The concentration of dissolved carbon dioxide affects the pH and _ _ other properties of the drink. A stable amount of dissolved carbon dioxide will equal a more consistent taste of the beverage product. Another aspect of this invention is the control of the release rate of carbon dioxide and that this rate of release does not materially exceed the rate of permeation of the package. The over-pressurization of carbonated beverage bottles is a significant problem and can lead to the rupture of the container, an economic and safety consideration. Any C02 regulation system effective for a carbonated beverage must not release carbon dioxide at a rate significantly greater than the rate of C02 loss from the container. Ideally, the release speed should be equal to or slightly less than the permeation speed of the package and should not exceed a speed of 125% of the package's permeation rate. You should also be able to release the C0 consistently for an extended period of time ideally for a period of up to three months and for at least two weeks. Another aspect of this invention is that it is self-regulating with respect to the thermal environment of the package such that in a warmer environment when the carbonation losses are higher, the regulators naturally release higher amounts of carbon dioxide which replenish the losses. Another aspect of this invention is to provide a packaging system which can allow over-carbonation without increasing the pressure within the package and allowing lighter weight bottles to be acceptable for supporting carbonated beverages. Adding extra carbonation at the filling point is a very method. economic to extend the life of carbonated beverage storage and is currently used in the packaging of soft drinks and beer. This is limited by the ability of the container to maintain this initial pressure level higher. A system which absorbs and releases this carbon dioxide expands the amount of over-carbonation which can be done during filling and will facilitate the use of vessels with a resistance to the lowest pressure. The regulation of carbon dioxide will also facilitate the use of containers which have lower modules. Many plastics are not suitable for packaging carbonated beverages because they can not contain the high internal pressures which can be developed with carbonated soft drinks. An example are polyolefins such as polypropylene. The use of a carbonation regulator with a lower modulus plastic such as polypropylene could make it more generally useful for packaging carbonated beverages. This invention has been described for the purposes of illustration only in combination with certain embodiments. However, it is recognized that various changes, additions, improvements, and modifications to the illustrated modes may be made by those skilled in the art, all falling within the scope and spirit of the invention. It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Claims (36)

1. CLAIMS Having described the invention as above, the content of the following claims is claimed as property: 1. A method for replenishing carbon dioxide gas in a carbonated beverage container, characterized in that it comprises: i) Inserting a carbon dioxide regulator inside the container or inside a container closing device; ii) Release carbon dioxide from the regulator. _ of ___ carbon dioxide by way of a chemical reaction; and iii) Regulating the release of carbon dioxide from the carbon dioxide regulator at a rate approximately equal to the rate of carbon dioxide loss from the container.
2. 2. The method of compliance with the claim 1, characterized in that the carbon dioxide regulator comprises polymeric carbonates and organic carbonates, individually, or in combinations thereof.
3. 3. The method of compliance with the claim 2, characterized in that organic carbonates have a carbon dioxide density of between about 0.25 and about 0.9 grams per cubic centimeter.
4. 4. The method according to claim 1, characterized in that the carbon dioxide released from the carbon dioxide regulator of step (iii) is regulated by steam.
5. 5. The method of compliance with the claim 4, characterized in that the carbon dioxide regulator is an organic carbonate comprising alkyl carbonates, dialkyl carbonates, ethylene carbonate, propylene carbonate, polypropylene carbonate, vinyl carbonate, glycerin carbonate, butylene carbonate, carbonate diethyl, ethyl pyrocarbonate, methyl pyrocarbonate, dialkyl dicarbonate, and cyclic carbonate acrylates.
6. The method according to claim 1, characterized in that the carbon dioxide released from the carbon dioxide regulator of step (iii) is regulated by covers, coatings, or films, individually, or in combination thereof.
7. The method according to claim 1, characterized in that the carbon dioxide regulator is housed in an insert which has a thickness of between about 0.025 cm (0.01 inches) to about 0.762 cm (0.3 inches).
8. 8. The method according to claim 1, characterized in that the chemical reaction of step (ii) comprises an oxidation reaction. .
9. The method according to claim 1, characterized in that the chemical reaction of step (ii) comprises a hydrolysis reaction.
10. 10. A method for replenishing carbon dioxide gas in a carbonated beverage container, characterized in that it comprises i) Inserting a carbon dioxide regulator into the container or into a container closure device; and ii) Regulate the release of carbon dioxide from the carbon dioxide regulator at a rate approximately equal to the rate of carbon dioxide loss from the container.
11. The method according to claim 10, characterized in that the carbon dioxide regulator is an absorbent that absorbs and subsequently releases carbon dioxide gas.
12. The method according to claim 10, characterized in that the carbon dioxide regulator. it can optionally be pre-charged with carbon dioxide prior to inserting the carbon dioxide regulator into the container.
13. The method according to claim 10, characterized in that the carbon dioxide regulator can optionally be charged by placing an insertion of the carbon dioxide regulator. carbon dioxide regulator within a closure device or mouth of the container and subsequently overpresurbed the container with an appropriate amount of carbon dioxide.
14. 14. The method according to the claim 10, characterized in that the carbon dioxide regulator comprises materials that absorb and subsequently release carbon dioxide.
15. 15. The method according to claim 14, characterized in that the carbon dioxide regulator comprises molecular sieves.
16. The method according to claim 14, characterized in that the carbon dioxide regulator comprises silicas gels, molecular sieves, clays, activated alumina, zeolites, coordinating polymers, organic metal structures, and organic metal isorecticular structures.
17. 17. The method according to claim 10, characterized in that the insertion of step (i) occurs such that the carbon dioxide regulator is not in contact with carbonated beverages.
18. 18. The method according to claim 10, characterized in that the carbon dioxide regulator can be mixed directly into the material of the container or closure device.
19. 19. A packaging system for maintaining a consistent pressure of a carbonated beverage because it comprises a closure device, a plastic container, and a carbon dioxide regulator.
20. 20. The packaging system according to claim 19, characterized in that the closure device comprises any materials used to seal the plastic container, such as a plastic assembly of the closure device and the cover material thereon.
21. 21. The packaging system according to claim 19, characterized in that the carbon dioxide regulator can be mixed within any materials used to produce the plastic container, the closure device, or the cover material.
22. 22. The packaging system according to claim 19, characterized in that the carbon dioxide regulator can be inserted into the plastic container or closure device in a form suitable for the plastic container.
23. 23. The packaging system according to claim 19, characterized in that the carbon dioxide regulator can be part of a regulator assembly by overmolding a preform around the regulator assembly using PET.
24. 24. The packaging system in accordance with the claim 23, characterized in that the preform is manufactured inside a plastic container.
25. 25. The packaging system according to claim 19, characterized in that the carbon dioxide regulator can be added as a layer in the plastic container.
26. 26. The packaging system according to claim 19, characterized in that the carbon dioxide regulator can be added as a layer in the closure device.
27. 27. A method for developing a packaging system for maintaining a pressure consisting of a carbonated beverage because it comprises overmolding a preform around an assembly for a carbon dioxide regulator.
28. 28. The method of compliance with the claim 27, characterized in that overmolding occurs by placing the assembly on a pin of the center of a mold by conventional injection and subsequently molding the preform around the assembly.
29. 29. The method of compliance with the claim 27, characterized in that the preform is made inside a plastic container.
30. 30. A method for developing a packaging system for maintaining a pressure consisting of a carbonated beverage, characterized in that it comprises mixing a carbon dioxide regulator within the thermoplastic material used to form the body of a container for the carbonated beverage.
31. 31. A 5 carbon dioxide regulator composition for replenishing carbon dioxide gas in a carbonated beverage container, characterized in that it comprises polymeric carbonates and organic carbonates, individually, or in combinations thereof.
32. 32. The composition in accordance with the 10 claim 31, characterized in that the polymeric carbonates comprise cyclic carbonate polymers and linear aliphatic carbonate polymers.
33. 33. The composition according to claim 31, characterized in that the carbonates The organic compounds include alkyl carbonates, dialkyl carbonates, ethylene carbonate, propylene carbonate, polypropylene carbonate, vinyl carbonate, glycerin carbonate, butylene carbonate, diethyl carbonate, ethyl pyrocarbonate, methyl pyrocarbonate, bicarbonate. 20 dialkyl, and cyclic carbonate acrylates.
34. 34. A composition of the carbon dioxide regulator for replenishing carbon dioxide gas in a carbonated beverage container, characterized in that it comprises materials that absorb and subsequently release 25 carbon dioxide.
35. 35. The composition according to claim 34, characterized in that the material that absorbs and subsequently releases carbon dioxide comprises molecular sieves.
36. 36. The composition according to claim 34, characterized in that the materials that absorb and subsequently release carbon dioxide comprise silicas gels, molecular sieves, clays, activated alumina, zeolites, coordination polymers, organic metal structures, and organic metal structures. isorecticular.