Aluminum containers containing dicarbonate diesters

Description

[0001] The invention relates to aluminum containers containing dicarbonic acid diesters and a process for producing the packaged dicarbonic acid diesters.

[0002] Dicarbonic acid diesters, particularly dimethyl dicarbonate and diethyl dicarbonate, are used in the beverage industry for the cold sterilization of non-alcoholic carbonated or still fruit juice drinks, fruit juices, wines, non-alcoholic wines, ciders, iced teas, and other beverages. This beverage stabilization technology offers several advantages. The most notable advantage is that, unlike hot filling, taste and color are not affected. Compared to persistent preservatives such as sodium benzoate or benzoic acid or potassium sorbate or sorbic acid, the advantage is particularly the absence of any taste impairment. Compared to cold aseptic filling, the significantly lower investment costs for plant technology are a particularly recognized advantage of using dicarbonic acid diesters.

[0003] Other applications of dicarbonic acid diesters, such as the inactivation of enzymes or use in batteries, are also described.

[0004] The substance class of dicarbonic acid diesters has the special property of hydrolyzing into the derived alcohols and carbon dioxide upon contact with corresponding beverages. Typical examples of dicarbonic acid diesters are dimethyl dicarbonate, diethyl dicarbonate, diisopropyl dicarbonate, di-n-propyl dicarbonate, and di-tert-butyl dicarbonate.

[0005] Depending on the temperature of the beverage during use, the active substance is no longer present in the beverage after a relatively short time. At typical temperatures between 5 and 20 °C, this occurs after a few hours. However, hydrolysis is also initiated by even the smallest amounts of water.

[0006] The decomposition of dicarbonic acid diesters is not limited to hydrolysis; degradation also occurs through spontaneous decarboxylation. This produces carbon dioxide and dialkyl carbonate. Since dimethyl dicarbonate is generally low in stability and has a fundamental tendency toward hydrolysis and decarboxylation, methods for stabilizing dicarbonic acid diesters during production, storage, and transport have been described. Despite the methods described, storage and transport remain an unresolved problem, as uncontrolled and untimely decomposition leads to the premature destruction of the dicarbonic acid diesters and to a buildup of pressure within the containers. This, in turn, can pose hazards when handling such decomposing containers.

[0007] Typically, dicarbonic acid diesters are filled and transported in glass containers using state-of-the-art technology. The stability of dicarbonic acid diesters in glass containers is satisfactory, but often represents a limitation in technical applications. Typical shelf life for dimethyl dicarbonate, for example, is a maximum of 12 months for food use. An extension of storage times would be desirable. Furthermore, the use of liquid substances in glass is always problematic, as glass breaks easily and leakage cannot be prevented in the event of breakage. For this reason, polymer-coated glass containers are sometimes used on the outside, but these are expensive to manufacture. Furthermore, according to state-of-the-art technology, the glass container is transported in Styrofoam packaging, which is also relatively expensive and cumbersome.

[0008] Despite these measures, a glass container must always be handled very carefully to avoid glass breakage, which is a major disadvantage.

[0009] Furthermore, glass is problematic for storing chemicals that can release gases, as excess pressure in the glass containers can cause them to burst, and the flying glass fragments can then pose an additional safety risk to employees. The polymer outer layer of the glass containers can also be attacked by heat or mechanical impact.

[0010] In addition to glass, metal containers are also known as packaging materials for all kinds of materials. Unfortunately, dialkyl dicarbonates decompose relatively quickly in all known metal containers. Due to their light weight and corrosion resistance, aluminum containers are particularly popular in the food industry. To improve their resistance to food contact, a number of coated aluminum containers have been described.

[0011] For example, US-B2-8142858 discloses containers made of aluminum metal coated with epoxy resins or a multi-layer system of polyester resins, polyvinyl chloride, and polymethacrylate resins. These multi-coated containers are suitable for the transport and storage of food and beverages.

[0012] It is known from US-B2-6008273 that epoxy resins or phenolic resins can be used to form a waterproof layer on metal bottles, especially aluminum bottles.

[0013] Aluminum bottles are known from US-B-8001961, which can be coated with phenolic epoxy resins and are then used for the transport and storage of light-sensitive, gaseous anesthetics.

[0014] DE-A-19912794 discloses aluminum bottles coated with mixtures of polyester resins and resole resins, which are essentially free of bisphenol A diglycidyl ethers. These bottles are intended for filling with food and beverages.

[0015] US-A-3936269 describes the filling of dimethyl dicarbonate into bottles, containers and cans with the aim of preserving the beverages and food contained therein.

[0016] It is known from US-A-3186906 that even non-perishable items, such as aluminum containers, can be sterilized with dimethyl dicarbonate and reused.

[0017] CN-U-204368790 describes a battery acid reservoir, wherein the battery acid is composed of LiPF 6 and other substances, one of which could be dimethyl carbonate.

[0018] DE-A-102007045958 describes a process for producing microbially stabilized beverages, in which a dialkyl dicarbonate is added to the beverage in the form of an aqueous and / or organic solution. Processes for treating the dicarbonic acid diesters have also been disclosed, which are intended to improve transport and storage properties. For example, US-A-3936269 proposes a process in which dimethyl dicarbonate is transported and stored in a frozen state and thawed again for use. In a frozen state, dimethyl dicarbonate is significantly more stable and storable, but its handling is technically much more complex and therefore associated with high costs, and is not used in practice.

[0019] The stability of dicarbonic acid diesters cannot be adequately guaranteed in existing transport and storage systems.

[0020] The task therefore remained to find new transport containers for dicarbonic acid diesters that would overcome the disadvantages of the state of the art.

[0021] Surprisingly, it has now been found that dicarbonic acid diesters can be stored and transported in aluminum containers with polymer coatings on the inside, essentially without decomposition.

[0022] The invention therefore relates to an aluminium container containing a filling material, wherein the filling material comprises at least one compound of the formula (I) wherein R 1< and R 2< independently of one another represent straight-chain or branched C 1 -C 5 alkyl, and the aluminum container is coated with at least one polymer, at least on the inside, wherein this polymer is polyester. Most preferably, R 1< and R 2< independently of one another represent methyl or ethyl.

[0023] Even more preferred compounds of formula (I) are dimethyl dicarbonate or diethyl dicarbonate or mixtures thereof.

[0024] The filling material generally consists of compounds of formula (I) or mixtures of compounds of formula (I). The filling material can also contain further additives, such as inorganic or organic alkali or alkaline earth metal salts, drying agents such as calcium chloride or silica gel, or oxygen scavengers such as sulfites or phosphates. The filling material preferably contains no further additives. The term filling material encompasses the compounds to be transported and / or stored. The term filling material preferably does not include the protective gases or air that may additionally be contained in the aluminum container. The compounds of formula (I) or mixtures of compounds of formula (I) are preferably contained in the aluminum container in an amount of 90 to 100%, based on the total amount of the filling material.The compounds of formula (I) or mixtures of compounds of formula (I) are particularly preferably present in the aluminum container in an amount of 95 to 100%, very particularly preferably in an amount of 98 to 100%, based on the total amount of the contents. Even more preferably, the compounds of formula (I) are present in the aluminum container in an amount of 99 to 100%, based on the total amount of the contents.

[0025] For the purposes of the invention, aluminum containers are understood to mean all containers that have an aluminum layer, at least on the inside, that can be coated with the polymer. The "inside" within the meaning of the invention refers to the side of the aluminum container that is in contact with the contents via the polymer coating. The outside of the container can also be made of another metal, an alloy, or plastic. The aluminum container is preferably made entirely of aluminum and has a polymer coating on the inside. The aluminum coated with the polymer preferably has a purity of > 99%.

[0026] The aluminum container is coated with at least one polymer, at least on the inside, which polymer is polyester. The aluminum container may be coated with other polymers.

[0027] The polymers according to the invention are preferably polyesters, phenolic resins, acrylic resins, amino resins or epoxy resins, which can also be used as mixtures.

[0028] Various commercially available polyesters are suitable for use in the present invention. Preferably, VITE® polyesters (e.g., VITE® PE-100 and PE-200 saturated polyesters available from Goodyear Tire and Rubber Co., Akron, Ohio), URALAC® polyesters (e.g., URALAC® ZW5000SH, URALAC® SN978, URALAC® SN908 available from Royal DSM NV), and Dynapol® polyesters (e.g., Dynapol® LH and L, saturated polyester resins available from Evonik Industries AG, Marl) are used as the polyester. URALAC® XP 8481 SN (Royal DSM NV) is particularly preferably used as the polyester.

[0029] The polyester preferably has an average molecular weight (MW) of 500 to about 10,000 g / mol, more preferably 1,000 to 7,500 g / mol. The glass transition temperature (Tg) of the polyester is preferably greater than or equal to 50°C, more preferably greater than or equal to 60°C. The glass transition temperature of the polyester is preferably less than or equal to 100°C.

[0030] The term polyester encompasses polyesters that can be made from the same or different, i.e., mixed, monomers. Polyesters are typically made from polycarboxylic acids or anhydrides, or mixtures thereof, and polyols. Polyesters are produced using known condensation or esterification processes, such as those described in Zeno Wicks, Jr., Frank N. Jones, and S. Peter Pappas, Organic Coatings: Science and Technology, Vol. 1, pp. 122-132 (John Wiley and Sons: New York, 1992).

[0031] Preferred polycarboxylic acids for producing the polyesters are maleic acid, fumaric acid, succinic acid, adipic acid, phthalic acid, 5-tert-butylisophthalic acid, azelaic acid, sebacic acid, chlorendic acid, isophthalic acid, trimellitic acid, terephthalic acid, methyltetrahydrophthalic acid, methylhexahydrophthalic acid, tetrahydrophthalic acid, dodecanedioic acid, azelaic acid, naphthalenedicarboxylic acid, pyromellitic acid and dimer fatty acids, cyclohexanedicarboxylic acid, such as in particular 1,4-cyclohexanedicarboxylic acid, glutaric acid, 12-hydroxystearic acid, 2-hydroxypropionic acid and 2-hydroxybutyric acid and mixtures thereof. Particular preference is given to using dicarboxylic acids, such as in particular phthalic acid, isophthalic acid, terephthalic acid, 1,4-cyclohexanedicarboxylic acid, succinic acid, sebacic acid, methyltetrahydrophthalic acid, methylhexahydrophthalic acid, tetrahydrophthalic acid, dodecanedioic acid, adipic acid, azelaic acid, naphthalenedicarboxylic acid, pyromellitic acid and dimer fatty acids.

[0032] Preferred anhydrides are succinic anhydride, maleic anhydride, phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, endomethylenetetrahydrophthalic anhydride, tetrachlorophthalic anhydride, trimellitic anhydride, pyromellitic dianhydride, as well as the acid anhydrides of the preferred polycarboxylic acids and their lower alkyl esters, especially their methyl esters. Preferred lower alkyl esters of the polycarboxylic acids are dimethyl terephthalate, dimethyl succinate, and dimethyl adipate.

[0033] Polyols which can preferably be used are ethylene glycol, propylene glycol, 1,2- and 1,3-propanediol, diethylene glycol, dipropylene glycol, triethylene glycol, tetraethylene glycol, 1,4-butanediol, 1,3-butylethylpropanediol, 2-methyl-1,3-propanediol, 1,5-pentanediol, cyclohexanedimethanol, tricyclodecanedimethanol, glycerol, 1,6-hexanediol, neopentyl glycol, pentaerythritol, trimethylolethane, trimethylolpropane, 1,4-benzyldimethanol and ethanol, 2,4-dimethyl-2-ethylhexane-1,3-diol, a polyethylene or polypropylene glycol with an average molecular weight (Mw) of less than or equal to 500 g / mol, isopropylidene bis(p-phenyleneoxypropanol-2) and mixtures thereof. Diols are particularly preferred as polyols. Preferred diols are ethylene glycol, propylene glycol, diethylene glycol, neopentyl glycol, and mixtures thereof.

[0034] Trimethylolpropane, neopentyl glycol, tricyclodecanedimethanol or 1,4-butanediol or mixtures thereof are particularly preferably used as polyols.

[0035] The polyester used preferably has hydroxyl or carboxyl groups as end functionalities. The polyester used particularly preferably has hydroxyl groups as end functionalities. This is usually achieved by using an excess amount of polyols during the esterification reaction.

[0036] Phenolic resins can also be used as polymers within the meaning of the invention. The term "phenolic resin" encompasses phenolic resins produced from the same or different, i.e., mixed, monomers. Phenolic resins used are the condensation products of aldehydes with phenols. Formaldehyde and acetaldehyde are preferably used as aldehydes. Xylenol, cresol, p-phenylphenol, p-tert-butylphenol, p-tert-amylphenol, and cyclopentylphenol are preferably used as phenols. The usable phenolic resins preferably contain at least two or more reactive hydroxyl groups as functional groups so that the phenolic resins can be crosslinked with the polyesters. Preferably, the phenolic resins are substantially free of bisphenol A (BPA), bisphenol F (BPF), bisphenol A diglycidyl ether (2,2'-bis(4-hydroxyphenyl)propane bis(2,3-epoxypropyl) ether) (BADGE) and bisphenol F diglycidyl ether (BFDGE).

[0037] For the purposes of the invention, the term "essentially free from" means that the content of the compounds mentioned is < 5 ppm.

[0038] Phenolic plastics etherified with butanol are particularly preferred as phenolic plastics.

[0039] Preferably, commercially available phenolic plastics are used, such as in particular DUREZ ®< and VARCUM ™< from DUREZ Corp. (Dallas, Tex.) or Reichhold Chemical AG (Austria); (CO) POLYMEROX ™< from Monsanto Chemical Co. (St. Louis, MO); Arofene ™< and Arotap ™< from Ashland Chemical Co. (Dublin, Ohio); and BAKELITE ®< from Bakelite AG (Iserlohn, Germany) or Phenodur ®< PR 899, or Phenodur ®< PR515 or Phenodur ®< PR516 (Allnex GmbH) or mixtures of these phenolic plastics.

[0040] Particularly preferred phenolic plastics are BAKELITE PF 6470 LB ®< , Bakelite 9989LB ®< , VARCUM 2227 B55 ®< , Phenodur ®< PR 899, Phenodur ®< PR515 or Phenodur ®< PR516 or mixtures of these phenolic plastics.

[0041] Epoxy resins can also be used as further polymers within the meaning of the invention. The epoxy resins used are preferably the reaction products from the reaction of phenols with epoxides. Particular preference is given to the epoxy resins from the reaction of bisphenol A, bisphenol F, phenol, butylphenol, xylenol, and cresol with epichlorohydrin. Even more preferred epoxy resins are Epikote®< 828 from Hexion GmbH, Germany.

[0042] Polyacrylates can also be used as additional polymers. Polyacrylates within the meaning of the invention are preferably polymethacrylates or polyacrylates of acrylic acid. These polyacrylates preferably contain functional groups, such as carboxyl, hydroxyl, or oxirane groups. Even more preferably, the polyacrylates contain at least one carboxyl group or one oxirane functional group, optionally in combination with one or more hydroxyl groups.

[0043] In a preferred embodiment of the invention, polyacrylates with an average molecular weight (MW) of 1,000 to 50,000 g / mol, preferably of 2,000 to 25,000 g / mol, and particularly preferably of 5,000 to 10,000 g / mol, are used. The glass transition temperature of the polyacrylates is preferably in the range of -24 °C to 105 °C and more preferably in the range of 50 °C to 90 °C.

[0044] Preferably, the polyacrylate is a copolymer of methacrylic acid (MA) and acrylic acid (AA) with ethyl methacrylate and butyl methacrylate or a copolymer of 2-hydroxyethyl methacrylate (HEMA) with ethyl methacrylate or a copolymer of glycidyl methacrylate (GMA) with ethyl methacrylate or a copolymer of glycidyl methacrylate with hydroxypropyl methacrylate and styrene.

[0045] The polyacrylate is produced by known chemical synthesis processes, for example by polymerization of ethylenically unsaturated acrylic monomers by radical polymerization.

[0046] In a further embodiment of the invention, the polymers are aminoplasts. Aminoplasts include the condensation products of aldehydes, such as formaldehyde, acetaldehyde, crotonaldehyde, and benzaldehyde, with compounds containing amino or amido groups, such as urea, melamine, and benzoguanidine. Preferably, aminoplasts with two or more amino groups as functional groups are used.

[0047] Suitable aminoplasts are preferably benzoguanidine-formaldehyde polymers, melamine-formaldehyde polymers, esterified melamine-formaldehyde polymers, and urea-formaldehyde polymers. The preferred aminoplast is the fully alkylated melamine-formaldehyde polymer, which is commercially available from Cytec Industries (Cytec Industries GmbH, Neuss, Germany) under the trade name CYMEL ®< 303.

[0048] In a further embodiment of the invention, the polymers are crosslinked. Any suitable crosslinker containing hydroxyl, amino, vinyl, or isocyanate groups can be used. In a preferred embodiment of the invention, the polymers, such as, in particular, aminoplasts, phenolplasts, or epoxy resins, serve as crosslinkers.

[0049] In a further embodiment of the invention, the polymers can also be crosslinked by isocyanate groups. Preferably, aliphatic and cycloaliphatic polyisocyanates, such as hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), bis[4-isocyanatocyclohexyl]methane (TMXDI), tetramethylene-m-xylidine diisocyanate (H 12 MDI), isopropenyldimethylbenzyl isocyanate (TMI), dimers or trimers thereof, and mixtures thereof, are used as isocyanates. Suitable commercially available isocyanate crosslinkers are preferably VESTANAT®< B 1358 A, VESTANAT®< EP B 1186 A, VESTANAT®< EP B 1299 SV (Evonik Resource Efficiency GmbH, Marl, Germany), and DESMODUR®< BL 3175 (Bayer AG, Leverkusen, Germany).

[0050] The polymers can be used without further auxiliaries, especially if the polymers are liquid at room temperature and under atmospheric pressure, or they can be mixed with other organic solvents, lubricants, catalysts, pigments, and additives. For the purposes of this invention, polymer compositions refer to polymers in the presence or absence of other organic solvents, lubricants, catalysts, pigments, and additives. Preferred polymer compositions are those containing polymers in the presence of other organic solvents, lubricants, catalysts, pigments, and / or additives.

[0051] Organic solvents which are particularly useful as carrier liquids for the polymers are preferably aliphatic hydrocarbons, such as, for example and preferably, mineral spirits, kerosene and P naphtha; aromatic hydrocarbons, such as, in particular, benzene, toluene, xylene or solvent naphtha 100, 150, 200 (Exxon Chemicals GmbH); alcohols, such as, in particular, ethanol, n-propanol, isopropanol, n-butanol or isobutanol; ketones, such as, in particular, 2-butanone, cyclohexanone, methyl aryl ketones, ethyl aryl ketones or methyl isoamyl ketones; esters, such as, in particular, ethyl acetate or butyl acetate; glycols, such as, in particular, butyl glycol, glycol ethers, such as, in particular, methoxypropanol; Glycol ethers, such as in particular ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, propylene glycol monomethyl ether; glycol esters, such as in particular butyl glycol acetate or methoxypropyl acetate, or mixtures thereof.Solvent naphtha 100, 150, or 200, or mixtures thereof, are particularly preferred. Solvent naphtha is also known under the trade name Solvesso™.

[0052] Catalysts can be used to increase the rate of curing or crosslinking.

[0053] Preferably, quaternary ammonium compounds, phosphorus compounds, tin and zinc compounds, such as preferably tetraalkylammonium halide, a tetraalkylammonium or tetraarylphosphonium iodide or acetate, tin octoate, zinc octoate, triphenylphosphine or mixtures thereof are used as catalysts.

[0054] Particularly preferred catalysts are phosphoric acid ester solutions, such as preferably ADDITOL XK 406™< (Cytec Surface Specialties, Inc., West Paterson, NJ) or sulfonic acids, such as preferably CYCAT 600™< (Cytec Surface Specialties, Inc., West Paterson Dodecylbenzene, NJ) or mono- and di-octyl tin mercaptides, such as preferably Tinstab OTS 17 MS™< (AKZO-Nobel Chemicals, Inc., Chicago, Ill.) or dibutyltin dilaurate, such as preferably FASCAT™< (Atofina Chemicals, Inc., Philadelphia, Pa.) or mixtures of these catalysts.

[0055] In a preferred embodiment, the catalyst is used in an amount of 0.05 wt.% to 5 wt.%, preferably in an amount of 0.1 to 1.5 wt.%, based on the weight of the polymer composition.

[0056] The polymer compositions may contain lubricants. Long-chain aliphatic waxes, such as carnauba waxes (Luba-Print 887 / C-Wachs-Dispersion, Münzing Chemie GmbH, Abstatt, Germany), synthetic wax dispersions, such as Lanco™ GLIDD 4518V (Lubrizol, Corp., Wickliffe, Ohio), Lanco™ Wax TF 1780 EF, Lanco™ Wax 1350 FF (Lubrizol, Corp., Wickliffe, Ohio), polyethylene, polypropylene, lanolin, polytetrafluoroethylene, and mixtures of these compounds, are preferably used as lubricants.

[0057] Pigments can also be added to the polymer composition. Suitable pigments such as aluminum flakes, titanium dioxide, and zinc oxide are commonly used to improve the appearance of the protective layer. If aluminum flakes are used as pigments, they are preferably used in an amount of 2 wt.% to 15 wt.%, and more preferably in an amount of 5 wt.% to 10 wt.%, based on the weight of the polymer composition. A pigment such as titanium dioxide is preferably used in an amount of 35 wt.% to 50 wt.%, and even more preferably in an amount of 40 wt.% to 45 wt.%, based on the weight of the polymer composition. If zinc oxide is used as a pigment, it is preferably present in an amount of 0.5 wt.% to 30 wt.%, and even more preferably in an amount of 5 wt.% to 15 wt.%, based on the weight of the polymer composition.

[0058] Particularly preferably, the amount of pigments in the polymer composition is less than 300 ppm. Even more preferably, the amount of pigments in the polymer composition is less than 50 ppm. Even more preferably, the polymer composition contains no pigments.

[0059] It depends on the respective application whether the polymer composition may contain further additives, such as water, surfactants, dispersants (preferably lecithin), defoamers (preferably modified polysiloxanes), thickeners (preferably methylcellulose), or fillers, such as preferably silicates or aluminum / magnesium hydroxides as well as magnesium oxide, calcium oxide or carbon black or mixtures thereof.

[0060] The amount of fillers in the polymer composition is particularly preferably less than 300 ppm. The amount of fillers in the polymer composition is even more preferably less than 50 ppm. Even more preferably, the polymer composition contains no fillers.

[0061] The polymer composition is preferably prepared by simply mixing the polymer and any optional ingredients in any desired order with sufficient stirring. The resulting mixture is preferably mixed until all ingredients of the composition are substantially homogeneously blended. Preferably, the polymer composition is prepared at temperatures between 10°C and 50°C.

[0062] The polymer composition is preferably applied to the aluminum surface in liquid form as a solution, suspension, or dispersion. This can be done by brushing, dipping, rolling, spraying, or similar methods. The suspension is preferably applied to the aluminum surface of the container by spraying.

[0063] When applied as a liquid coating, the polymer composition preferably has a solids content of from 25 wt% to 70 wt% non-volatile material, and more preferably from 30 wt% to 50 wt% non-volatile material.

[0064] In a preferred embodiment, the polymer composition contains 20 wt.% to 80 wt.% polyester and 1 wt.% to 80 wt.% organic solvents and less than 1 wt.% lubricants and / or catalysts.

[0065] In a further preferred embodiment, the polymer composition contains 20 wt.% to 75 wt.% polyester, 10 wt.% to 79 wt.% organic solvents and 1 wt.% to 25 wt.% other polymers, such as in particular polyacrylates, epoxy resins, phenolic resins or amino resins and less than 1 wt.% lubricants and / or catalysts.

[0066] In a further preferred embodiment, the polymer composition contains 20 wt.% to 75 wt.% polyester, 10 wt.% to 79 wt.% organic solvents and 1 wt.% to 25 wt.% phenolic resins and less than 1 wt.% lubricants and / or catalysts.

[0067] In a further preferred embodiment, the polymer composition contains 20 wt.% to 75 wt.% polyester, 10 wt.% to 79 wt.% organic solvents and 0.9 wt.% to 25 wt.% phenolic resins and 0 to 2 wt.% catalysts and 0.1 to 2 wt.% lubricants.

[0068] In a further preferred embodiment, the polymer composition contains 20 wt.% to 75 wt.% polyester, 10 wt.% to 79 wt.% organic solvents and 0.9 wt.% to 25 wt.% phenolic resins and 0 to 2 wt.% catalysts and 0.1 to 2 wt.% lubricants and less than 5 ppm fillers and / or pigments.

[0069] In a further preferred embodiment, the polyester is produced at least on the basis of pyromellitic dianhydride, tricyclodecanedimethanol, and the crosslinker isophorone diisocyanate. This polyester and the crosslinker are contained in particular in the products Gold Lacquer 32S23MC and Gold Lacquer BT651B from Valspar Corp., Minneapolis, MN, USA. Aluminum containers coated with this lacquer, in which the contents have been in contact with Gold Lacquer 32S23MC and / or Gold Lacquer BT651B, can be easily cleaned with aqueous solutions. The lacquer detaches from the aluminum surface during this cleaning process.

[0070] The curing process of the polymer composition on the surface is preferably carried out by heating, preferably at a temperature of 150 °C to 280 °C. The heating time is preferably 1 to 10 minutes.

[0071] The polymer compositions can be applied to aluminum sheets on an industrial scale by processes known to those skilled in the art, such as the so-called sheet-bake process, by roller coating, the coil coating process, by strip coating, or by spraying. The polymer composition is then cured by the action of heat, actinic radiation, e.g. by ultraviolet or infrared light, by electromagnetic radiation, e.g. electron beam curing, or by a combination of these processes. The coated sheets can then be formed into containers. However, it is also possible and preferred to coat the finished aluminum containers with the polymer composition, preferably by spraying. The polymer composition is preferably cured on the surface by heating.

[0072] The polymer coatings formed on the aluminum surface preferably have a thickness of 1 to 50 µm. More preferably, the polymer coatings have a thickness of 5 to 10 µm.

[0073] The scope of the invention encompasses all of the above and below listed general or preferred range definitions, parameters and explanations among each other, thus also between the respective ranges and preferred ranges in any combination.

[0074] The invention also includes a process for producing the previously described inventive aluminum container containing at least one compound of formula (I) wherein R 1< and independently of one another represent straight-chain or branched C 1 -C 5 alkyl, in which in a step a.) an aluminum container is coated with a polymer composition containing at least one polyester and this layer is cured in a step b.) and then in a step c.) the filling material is filled into this aluminum container, optionally under protective gas.

[0075] The filling material is preferably poured into the interior of the aluminum container through a filling spout. This filling process preferably takes place under a protective gas atmosphere. Suitable protective gases include argon, helium, or nitrogen. Nitrogen is the preferred protective gas. After filling, the opening is preferably sealed with a plastic cap, for example, available from Bericap in Budenheim, Germany. The plastic caps can contain additional inserts, such as sealing discs based on polytetrafluoroethylene (PTFE). One such insert is commercially available under the name "Plytrax 100" from Norton Performance Plastic Corporation, Wayne, NJ, USA. In this model, the PTFE layer in the cap is attached to the cap using a polyethylene foam.

[0076] The contents can generally be stored and transported at temperatures and pressures deemed suitable by a person skilled in the art. Storage and transport preferably takes place at temperatures between -78°C and +40°C, particularly preferably at temperatures between -38°C and +38°C, and most particularly preferably between -25°C and +25°C. The contents are preferably stored and transported at atmospheric pressure, i.e., no particular pressure is specified. The contents can be stored and transported in the presence or absence of a protective gas. Storage and transport preferably takes place in the presence of a protective gas. Nitrogen is preferably used as the protective gas.

[0077] Thanks to the special coated aluminum containers, the compounds of formula (I) can be stored at a purity of more than 97% for a period of one to three years. Particularly preferred, the compounds of formula (I) can be stored at a purity of more than 98% for a period of up to two years. Even more preferred, the compounds of formula (I) can be stored at a purity of more than 99% for a period of up to two years.

[0078] The aluminum container containing the contents is preferably connected to commercially available dosing pump systems. This makes it possible to easily dose the contents into other containers, preferably containing beverages, or into beverage lines. Therefore, the invention also encompasses the use of the aluminum container containing the contents in dosing pump systems for transferring and dosing into other containers or beverage lines.

[0079] By using the aluminum containers according to the invention, the compounds of formula (I) can be transported and stored without significant decomposition. In contrast, in the packaging conventionally used for transport, such as glass containers, a significant degradation of the active ingredient can be observed within a short period of time. Since the weight of aluminum containers is significantly lower than that of glass containers, the transport costs of the compounds of formula (I) can be reduced by using the aluminum containers according to the invention. In addition, the containers are not deformable by heat and reliably protect the contents from the effects of light. The aluminum containers used according to the invention can also be recycled. Examples Example 1 Production of the coated aluminum container

[0080] A polyester resin coating (Gold Coat BT651B (Valspar Corp.)) was sprayed onto the aluminum surface, particularly the surface facing the contents. The container was then heated to 190 °C for 10 minutes. The coating uniformity was then visually inspected. Example 2 Filling the aluminum container with dimethyl dicarbonate

[0081] The coated aluminum bottles from Example 1 are filled with dimethyl dicarbonate and sealed directly with a plastic cap from Bericap, Budenheim, Germany. The caps feature a polytetrafluoroethylene (PTFE) seal. The seal is commercially available under the name "Plytrax 100" and was purchased from Norton Performance Plastic Corporation, Wayne, NJ, USA. Example 3 Stability tests of dimethyl dicarbonate in different containers

[0082] 3 kg of dimethyl dicarbonate was filled into various commercially available and experimentally prepared containers listed in Table 1, then sealed and placed in various temperature cabinets for storage. The storage conditions, i.e., the storage time and storage temperature, under which the contents were stored in the containers can be found in Table 1. Analysis was performed using gas chromatography; the amount of dimethyl carbonate present, which is a decomposition product of the thermal decomposition of dimethyl dicarbonate, was determined. A high amount of dimethyl carbonate is found, indicating low stability of the dimethyl dicarbonate. Table 1 Storage temperature [°C] Dimethyl carbonate content [ppm] / after X days storage Uncoated aluminum (Fa. Leicht und Appelt, Bad Gandersheim, GER) 20 6724 ppm / 35 days Anodized aluminum (Leicht und Appelt, Bad Gandersheim, GER) 20 4462 ppm / 35 days Glass 20 / 40 / 20* 19591 ppm / 168 days Polyester resin coating on aluminum with a pigment content of less than 300 ppm. (Gold coating BT651B (Valspar Corp. AG, Grüningen, Switzerland) 20 / 40 / 20* 120 ppm / 365 days Polyester resin lacquer coated on aluminum with a pigment content of less than 300 ppm. (Gold lacquer 32S23MC (Valspar Corp. AG, Grüningen, Switzerland) 20 / 40 / 20* 840 ppm / 365 days *5 weeks storage at 20°C, then 4 weeks at 40°C, then further stored at 20°C

[0083] As can be seen from Table 1, dimethyl dicarbonate can be stored for significantly longer and is therefore more stable in an aluminum container coated with polyester lacquer than in uncoated or anodized aluminum containers. Summary

[0084] The invention relates to aluminum containers containing dicarbonic acid diesters and a process for producing the packaged dicarbonic acid diesters.

Claims

1. Aluminium containers containing filled product, characterized in that the filled product is at least one compound of the formula (I) in which R1 and independently of one another are straight-chain or branched C1-C5 alkyl, and the aluminium container is coated with at least one polymer at least on the inside, this polymer being polyester.

2. Aluminium containers containing filled product, according to Claim 1, characterized in that the compounds of the formula (I) are dimethyl dicarbonate or diethyl dicarbonate or mixtures thereof.

3. Aluminium containers containing filled product, according to Claim 1 or 2, characterized in that the compounds of the formula (I) are present as filled product in an amount of 90 to 100%, preferably in an amount of 95% to 100%, based on the total amount of the filled product.

4. Aluminium containers containing filled product, according to one or more of Claims 1 to 3, characterized in that the amount of fillers and / or pigments is less than or equal to 50 ppm in the polymer coating.

5. Aluminium containers containing filled product, according to one or more of Claims 1 to 3, characterized in that the thickness of the polymer layer is 5 to 10 µm.

6. Aluminium containers containing filled product, according to Claim 1, characterized in that the polymer is a polyester having an average molecular weight (MW) of 1000 to 7500 g / mol.

7. Aluminium containers containing filled product, according to Claim 1, characterized in that the polymer is a polyester having a glass transition temperature of less than or equal to 100°C.

8. Aluminium containers containing filled product, according to Claim 1, characterized in that the polymer is a polyester which has been prepared at least from pyromellitic dianhydride, tricyclodecanedimethanol and the crosslinker isophorone diisocyanate.

9. Method for producing an aluminium container containing filled product, according to Claim 1, containing at least one compound of the formula (I) in which R1 and independently of one another are straight-chain or branched C1-C5 alkyl, characterized in that in a step a.) an aluminium container is coated with a polymer composition containing at least one polyester and in a step b.) this layer is cured and then in a step c.) the product, optionally under inert gas, is filled into this aluminium container.

10. Method for producing an aluminium container containing filled product, according to Claim 9, characterized in that use is made as polymer composition in step a.) of a mixture containing 20 wt% to 75 wt% of polyester, 10 wt% to 79 wt% of organic solvents and 0.9 wt% to 25 wt% of phenolic resins and 0.1 to 2 wt% of lubricants, and less than 5 ppm of fillers and / or pigments.

11. Method for producing an aluminium container containing filled product, according to Claim 10, characterized in that the polymer composition in step a.) is applied by spraying to the aluminium surface of the container.

12. Method for producing an aluminium container containing filled product, according to one of Claims 10 and 11, characterized in that step b.) is carried out by heating at a temperature of 150°C to 280°C.

13. Use of the aluminium containers containing filled product, according to Claim 1, in metering pump systems for transferring and metering the product into other containers or beverage lines.