Processes and compositions for improving the mobility of aluminium cans when conveyed by automatic conveying equipment

Abstract: Contact of acid or alkaline cleaned aluminum surfaces, particularly cans, with a water based composition containing a combination of (A) water-soluble ethoxylated organic material selected from the group consisting of ethoxylated fatty acids, salts of ethoxylated fatty acids, ethoxylated alcohols having at least 4 carbon atoms and containing up to 20 moles of condensed ethylene oxide per mole of alcohol, ethoxylated alkyl alcohol phosphate ester, and mixtures thereof; and (B) an amount of hydrogen peroxide effective to prevent deterioration of the composition by the action of microorganisms, gives the surface after drying lowered surface friction without loss of high quality printability and lacquer adhesion and removes any brown spotting on the cans that may have developed during the cleaning or post-cleaning rinses. The cans after treatment are substantially free from any water breaks when rinsed with water. The foaming resistance and storage stability of the water based composition may be advantageously increased by adding a combination of liquid paraffin, solid wax, and a high molecular weight fatty acid derivative(s) as antifoam agent.

Description: This invention concerns processes and compositions for improving the mobility of aluminium cans when conveyed by automatic conveying equipment. It is already known, e.g. from United States Patent No. 4,859,351, that the mobility of an aluminium can when conveyed may be improved by contacting its exterior surface, after cleaning and before final drying, with an aqueous lubricant and surface conditioner composition so as thereby to form a film on the can surface after drying which reduces the coefficient of static friction of the surface of the can to not more than 1.5. This invention is particularly directed toward aqueous compositions suitable for contacting formed metal surfaces to deposit thereon after drying a mobility enhancing lubricant film, said compositions being protected against deterioration from the action of microorganisms during storage and/or against foaming during use. It is convenient at this point to note that in this description, except in the claims and the operating examples or where examples or where explicitly otherwise indicated, all numbers describing amounts of ingredients or reaction conditions are to be understood as modified by the word "about" in defining the broadest scope of the invention. Operation within the exact numerical limits specified is generally preferred. Also, except where otherwise stated, whenever more than one material is stated to be suitable for a particular component of a composition, it is to be understood that mixtures including any two or more of the listed materials are also equally suitable. It has now been found that the known lubricating and surface conditioning compositions, e.g. as in the above-mentioned U.S. Patent 4,859,351, need to be protected against deterioration from micro-organisms during storage and/or use and/or from foaming during preparation and/or use. One must however avoid the use of any antimicrobial or biocidal agent on the one hand, or any antifoam agent on the other, which will have a deterimental effect on the mobility-enhancing properties or the stability of the composition. According to one aspect of this invention there is provided a process for improving the mobility of an aluminium can when conveyed by automatic conveying equipment, comprising the steps of cleaning the can with an aqueous acidic or alkaline cleaning solution, drying the cleaned can, and subsequently conveying the cleaned and dried can via said conveying equipment to a location where it is lacquered or decorated by printing or both, at least one exterior surface of said aluminium can, prior to the last drying of said exterior before automatic conveying, being contacted with a lubricant and surface conditioner composition so as thereby to form a film on the can surface after drying which reduces the coefficient of static friction of the surface of the can to not more than 1.5, and in which the lubricant and surface conditioner composition employed contains an amount of hydrogen peroxide effective to prevent deterioration of the composition by the action of microorganisms during storage and use and/or an amount effective to reduce foaming of a mixture of solid wax, liquid paraffin and high molecular weight fatty acid derivative molecules. The lubricant and surface conditioner composition employed will preferably be otherwise an aqueous solution of water-soluble ethoxylated organic material being one or more of the following, namely ethoxylated fatty acid(s) and salt(s), amide(s), ether(s) and ester(s) of ethoxylated fatty acid(s) and of hydroxy-substituted ethoxylated fatty acid(s), and ethoxylated alcohol(s) and ethoxylated phosphate ester(s). The water-soluble ethoxylated organic material used will desirably be or include one or more ethoxylated fatty acid(s), salt(s) of ethoxylated fatty acid(s), ethoxylated alcohol(s) having at least 4 carbon atoms and containing up to 20 moles of condensed ethylene oxide per mole of alcohol and/or ethoxylated alkyl alcohol phosphate ester(s). The lubricant and surface conditioner composition employed should have a pH of between 1 and 6.5, and the pH of the lubricant and surface conditioner composition will advantageously be between 2.5 and 5. According to another aspect of this invention there is also provided a liquid lubricant and surface conditioner composition, suitable for use in the process disclosed herein by application to at least one exterior surface of a cleaned aluminium can to improve the mobility of the can when conveyed, said composition comprising a solution in water of water-soluble ethoxylated organic material being one or a mixture of more than one of the following, namely ethoxylated fatty acids, salts, amides, ethers and esters of ethoxylated fatty acids and of hydroxy-substituted ethoxylated fatty acids, ethoxylated alcohols and ethoxylated phosphate esters, together with an amount of hydrogen peroxide effective to prevent deterioration of the composition by the action of microorganisms during storage and use, said liquid lubricant and surface conditioner composition having a pH of between 1 and 6.5, and forming a film on the can surfce when applied thereto and dried which thereby reduces the coefficient of static friction of said surface. As already indicated in relation to the above-described process, the water-soluble organic material present in the composition will preferably be or include one or more ethoxylated fatty acids, salts of ethoxylated fatty acids, ethoxylated alcohols having at least 4 carbon atoms and containing up to 20 moles of condensed ethylene oxide per mole of alcohol and/or ethoxylated alkyl alchol phosphate esters. The composition will also very desirably have a pH between 2.5 and 5, and additionally comprise an amount effective to reduce foaming of a mixture of solid wax, liquid paraffin, and high molecular weight fatty acid derivative molecules. Hydrogen peroxide is the biocide of choice for the purposes of this invention. In aqueous concentrated compositions, suitable for dilution with about 99 times their own weight of water to make a composition ready for direct application to metal to enhance mobility after drying, as already described, concentrations of hydrogen peroxide in the range from 0.375 to 3.75 w% are preferred, with concentrations in the range from 1.4-2.2 w% most preferred. In more concentrated compositions the preferred biocide concentrations would be determined by the expected degree of dilution of the concentrate. In general, however, because of the relatively low stability of concentrated hydrogen peroxide, it is preferred that this component, if used, be added only to a sufficiently dilute concentrate that the concentration of hydrogen peroxide does not exceed about 3 w% at the time of making up the composition. And similarly, the antifoam agent of choice for use in the compositions is a combination of wax, low volatility liquid paraffin hydrocarbons, and high molecular weight fatty acid derivatives. An amount of this antifoam agent corresponding to 0.05 to 2 w% is generally preferred, with 0.5-1 w% generally more preferred. All the advantages of increased mobility, low surface coefficient of friction, high quality printability, and good adhesion of lacquers and the like as taught in the aforesaid United States Patent No. 4,859,351 are retained for treatments according to this invention. The practice of this invention may be further appreciated by consideration of the following non-limiting examples. EXAMPLE General Conditions In all these examples, the surfaces treated were those of conventional aluminium beverage cans already in their final shape and size. The cans were subjected to an acid prewash in an aqueous solution sulfuric acid having a pH of 2 for 30 seconds ("sec") at 54°C, then to washing with a conventional alkaline, surfactant containing cleaner at pH 12.3 for 60 sec at 54°C, and then to a 30 sec tap water rinse before being treated with a composition according to this invention as set forth in the specific examples below. (The compositions given in the specific examples are for concentrates according to this invention; for treatment, a solution of the w% of the concentrate specified in Table 1, in tap water, was used). After this treatment, the cans were rinsed first in tap water for 30 sec, then in deionized water for 90 sec, and dried at 210°C. The coefficient of static surface friction on the cans after drying was measured as described in the '351 patent. Example 1 This is an example of a composition that contains the antifoam agent and a biocide of this invention, but otherwise is according to the teachings of the aforesaid United States Patent No. 4,859,351. A first concentrate is prepared by mixing 880 parts by weight ("PBW") of ETHOX TM MI-14, 60 PBW of COLLOID 999 TM (a high molecular weight fatty acid derivative, available commercially from Colloids, Inc., 394 Frelinghuysen Ave., Newark, New Jersey 07114, U.S.A.), and 60 PBW of GP-295 TM Defoamer (a suspension of about 10% solid wax in white mineral oil, available commercially from Genese Polymers Corp., Flint, Michigan 48507, U.S.A.). The ETHOX TM MI-14 is first melted in a mixing tank at 27-32°C. The other two materials are then added in the order noted and mixed for form a cloudy but visually homogenous liquid with no lumps. A second concentrate suitable for storage for at least several months is then made by mixing 47 PBW of the first concentrate described above with 917 PBW of water, preferably deionized water, and with 40 PBW of 37.5% aqueous hydrogen peroxide. This second concentrate may then be diluted when desired to make a composition suitable for directly treating aluminium surface as generally described in the United States Patent No. 4,859,351 aforesaid.

Claims: A process for improving the mobility of an aluminium can when conveyed by automatic conveying equipment, comprising the steps of cleaning the can with an aqueous acidic or alkaline cleaning solution, drying the cleaned can, and subsequently conveying the cleaned and dried can via said conveying equipment to a location where it is lacquered or decorated by printing or both, at least one exterior surface of said aluminium can, prior to the last drying of said exterior before automatic conveying, being contacted with a lubricant and surface conditioner composition so as thereby to form a film on the can surface after drying which reduces the coefficient of static friction of the surface of the can to not more than 1.5, and in which the lubricant and surface conditioner composition employed contains an amount of hydrogen peroxide effective to prevent deterioration of the composition by the action of microorganisms during storage and use and/or an amount effective to reduce foaming of a mixture of solid wax, liquid paraffin and high molecular weight fatty acid derivative molecules. A process as claimed in claim 1, in which the lubricant and surface conditioner composition employed is otherwise an aqueous solution of water-soluble ethoxylated organic material being one or more of the following, namely ethoxylated fatty acid(s) and salt(s), amide(s), ether(s) and ester(s) of ethoxylated fatty acid(s) and of hydroxy-substituted ethoxylated fatty acid(s), and ethoxylated alcohol(s) and ethoxylated phosphate ester(s). A process as claimed in claim 2, in which the water-soluble ethoxylated organic material is or includes one or more ethoxylated fatty acid(s), salt(s) of ethoxylated fatty acid(s), ethoxylated alcohol(s) having at least 4 carbon atoms and containing up to 20 moles of condensed ethylene oxide per mole of alcohol and/or ethoxylated alkyl alcohol phosphate ester(s). A process as claimed in any of the preceding claims, in which the lubricant and surface conditioner composition employed has a pH of between 1 and 6.5. A process as claimed in claim 4, in which the pH of the lubricant and surface conditioner composition is between 2.5 and 5. A liquid lubricant and surface conditioner composition, suitable for use in the process claimed in any of the preceding claims by application to at least one exterior surface of a cleaned aluminium can to improve the mobility of the can when conveyed, said composition comprising a solution in water of water-soluble ethoxylated organic material being one or a mixture of more than one of the following, namely ethoxylated fatty acids, salts, amides, ethers and esters of ethoxylated fatty acids and of hydroxy-substituted ethoxylated fatty acids, ethoxylated alcohols and ethoxylated phosphate esters, together with an amount of hydrogen peroxide effective to prevent deterioration of the composition by the action of microorganisms during storage and use, said liquid lubricant and surface conditioner composition having a pH of between 1 and 6.5, and forming a film on the can surfce when applied thereto and dried which thereby reduces the coefficient of static friction of said surface. A composition as claimed in claim 6, in which the water-soluble organic material present is or includes one or more ethoxylated fatty acids, salts of ethoxylated fatty acids, ethoxylated alcohols having at least 4 carbon atoms and containing up to 20 moles of condensed ethylene oxide per mole of alcohol and/or ethoxylated alkyl alchol phosphate esters. A composition as claimed in claim 6 or claim 7, having a pH between 2.5 and 5 and which additionally comprises an amount effective to reduce foaming of a mixture of solid wax, liquid paraffin, and high molecular weight fatty acid derivative molecules.

Inventors: AWAD SAMI, AWAD, SAMI
Applicants: HENKEL CORP, HENKEL CORPORATION
Application year: 1991
Main classification: C10M173
IPC codes: C10M173