Classifications

• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
  • C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
  • C23C22/06—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6
  • C23C22/34—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing fluorides or complex fluorides

Definitions

• the invention is in the field of surface treatment of molded Metal parts made of aluminum or aluminum alloys as well as tinned Steel (tinplate). It particularly affects beverage and food cans from these materials.
• the invention pursues the goal in the process of Can manufacturing the can surfaces with a paintable, anti-corrosion To provide a layer that facilitates the drainage of water and which leads in particular to the fact that the coefficient of friction reduced between touching cans and thus the transport of Cans on conveyor belts are lightened, while maintaining porosity a later painting is reduced.
• Tins made of tinned steel (tinplate) and aluminum (or aluminum alloys, which in the following for simplicity under "aluminum” are summarized) are for storing food and in particular of beverages widely used.
• these are usually washed after shaping, for example acidic or alkaline cleaners are commercially available.
• This Cleaner solutions must have sufficient solvent power for those concerned Contain metals to effectively remove metal debris from the cans.
• the can surface itself can be roughened by the metal attack be, which increases the friction between touching cans elevated. This will reduce the speed of the can transport Conveyor belts are reduced and especially in places where there is separation If the cans build up a can backlog, the can can be transported completely be blocked. Because this increases the capacity of the production plant reduced, one tries to condition the can surfaces in such a way that the friction between touching cans is as low as possible becomes.
• chrome-free methods for surface treatment are in the prior art known from aluminum, which is usually inorganic acids, especially phosphoric acid, hydrofluoric acid or other sources of fluoride and / or use complex fluorides with or without additional Use organic polymers.
• inorganic acids especially phosphoric acid, hydrofluoric acid or other sources of fluoride and / or use complex fluorides with or without additional Use organic polymers.
• US-A-4,992,116 an aqueous acid treatment solution, the phosphate, a fluoric acid of Zr, Ti, Hf or Si and a polyphenol compound contains a Mannich adduct of a substituted amine with a polyalkylene phenol or represents a tannin.
• EP-B-8942 discloses treatment solutions preferably for aluminum cans containing a) 0.5 to 10 g / l polyacrylic acid or an ester here from and b) 0.2 to 8 g / l at least one of the compounds hexafluorozirconic acid, hexafluorotitanic acid or hexafluorosilicic acid.
• Conversion solutions for aluminum are known from US Pat. No. 4,470,853 among others 10 to 150 ppm zircon, 20 to 250 ppm fluoride, 15 to 100 ppm of phosphate and 30 to 125 ppm of tannin. Your pH is in the Range 2.3 to 2.95.
• the use of tannin in surface treatment of aluminum is also taught in DE-A-24 46 492, according to which one Aluminum is treated with an acidic, phosphate-containing solution, the one Contains metal salt of tannin in amounts between 0.1 and 10 g / l.
• W091 / 14014 describes an aqueous solution containing ions of Fe, Zr, Sn, Al or Ce, metal etching acids such as hydrofluoric acid, alkoxylated phosphoric acid esters and a combination of alkoxylated alcohols and alkoxylated alkylphenols.
• the W094 / 01517 describes a Process for the friction-reducing conversion treatment of metal cans, in which, in addition to inorganic metal compounds, alkoxylated or not alkoxylated castor oil triglycerides, hydrogenated castor oil derivatives, alkoxylated or non-alkoxylated amine salts of fatty acids, alkoxylated or non-alkoxylated amino fatty acids, alkoxylated or non-alkoxylated Fatty amine N-oxides, alkoxylated or non-alkoxylated quaternary ammonium salts or water-soluble organic polymers are used.
• EP-A-612 833 proposes a surface treatment to reduce friction with an ester between a polyglycerin and fatty acids in front.
• An effective surface treatment for tinplate or aluminum cans is intended on the one hand to meet the different requirements with regard to corrosion protection as well as freedom from pores and adhesion of a subsequent painting, each according to different requirements according to different Criteria are checked, sufficient and, on the other hand, the most effective Ensure a reduction in friction.
• Systems known to date compromises between the different requirements and do not fully satisfy all points.
• the task of The present invention is a solution for surface treatment of metal cans to provide an improved range of services with regard to the different requirements.
• the alkyl radicals R 1 can represent radicals with a certain chain length and a certain number of double bonds. For economic reasons, however, it is preferable to use amine oxides or ammonium salts derived from oleochemical raw materials. In these cases, the R 1 radicals have a distribution of chain lengths and double bonds as are characteristic of the fatty acids in vegetable or animal fats and oils. Preference is given to using those compounds of the general formula (I) in which R 1 represents a mixture of alkyl groups, such as in those fatty acid mixtures which can be obtained by hydrolysis of coconut oil, palm kernel oil or animal tallow.
• Suitable amine oxides of the general formula (I) are: bis (2-hydroxyethyl) cocoalkylamine oxide (Aromox R C / 12), bis (2-hydroxyethyl) tallow alkylamine oxide (Aromox R T / 12), dimethyl cocoalkylamine oxide (Aromox R DMC), hydrogenated dimethyl tallow alkylamine oxide (Aromox R DMHT) and dimethylhexadecylamine oxide (Aromox R DM-16), all of which are available from Akzo Chemicals Inc.
• quaternary ammonium salts of the general formula (I) are: dodecyltrimethylammonium chloride (Arquad R 12-37W), octadecyltrimethylammonium chloride (Arquad R 18-50), dimethylbenzyl- (C 12-18 ) alkylammonium chloride (Arquad R B-100), Tris ( 2-hydroxyethyl) tallow alkyl ammonium acetate (Ethoquad R T / 13) and methyl bis (2-hydroxy-2-methylethyl) ammonium methyl sulfate (Propoquad R T / 12), all of which are also available from Akzo Chemicals Inc.
• Preferred alkylamine oxides or quaternary ammonium salts of the general formula (I) are those which carry radicals R 2 , R 3 and, in the case of the quaternary ammonium salts, also R 4 , which form when the alkylamines are reacted with ethylene oxide, propylene oxide or butylene oxide. Examples include 2-hydroxyethyl groups and 2-hydroxy-2-methylethyl groups. As is customary in alkoxylation reactions, radicals R 2 , R 3 and R 4 can also be formed in which several alkoxy groups are linked to one another via ether bonds. Such polyether residues with up to 8 carbon atoms are also within the scope of the invention. However, particular preference is given to those compounds of the general formula (I) which bear 2-hydroxyethyl groups as radicals R 2 , R 3 and optionally R 4 .
• the components of the Group a) represents the active ingredients which reduce friction the effect of the components of group b) is one-, two- or three-base Hydroxycarboxylic acids with 4 to 7 carbon atoms in the molecule, the sum of hydroxyl and carboxyl groups is at least 3, primarily in that a later applied varnish has a reduced porosity and thus has an increased corrosion resistance.
• the porosity value referred to in the Anglo-Saxon literature as "Metal Exposure Value", MEV, can be determined and determined by an electrochemical measurement one of the quality requirements of the beverage industry for coated beverage cans
• This measured variable can, for example, with an "Enamel Rater MK “from Manfred Kunke, Berlin (Germany) or with a “Enamel Rater” from Wilkens-Anderson Co, Chicaco, Illinois become.
• the measurement is based on the fact that the beverage can is painted on the inside with an electrolytic solution (50.6 g of common salt and 1.19 g of dioctyl sodium sulfosuccinate in 5 liters of deionized water) and fill the can as an electrode switches.
• a counter electrode is immersed in the electrolyte solution and after switching on the voltage and a waiting time of 4 sec. the flowing Current read in mA. With a perfect coating of the can there is none Current flow expected. Increasing current flow in mA, the "Metal Exposure Value "shows an increasing permeability of the coating for ions that can be interpreted as porosity. For one later filling with soft drinks is required, for example, that the average MEV is below 5 mA at a test voltage of 6.3 V should lie.
• Suitable hydroxycarboxylic acids are malic acid, tartaric acid, citric acid and in particular those carboxylic acids which can be obtained by oxidation of pentose and hexose type sugars.
• suitable carboxylic acids are gluconic acid, sugar acid, mannosugar acid, mucic acid and glucuronic acid. Gluconic acid is particularly preferred.
• These acids can be used as such or in the form of their water-soluble salts, in particular their sodium salts.
• the hydroxycarboxylic acids are, depending on their pK partly as such and partly in the form of their anions.
• the other main components of the treatment solution according to the invention, c) and d), are in solutions for the conversion treatment of aluminum surfaces well known.
• the use of hexafluorozirconate is preferred. It is immaterial whether the complex fluorides as water-soluble salts, for example as sodium or ammonium salts, or used as free acids.
• the complex fluorine compounds so with the mineral acids of the Group d) or their acidic or neutral salts are combined in such a way that the treatment solution according to the invention has a pH in the effective range from 2.3 to 3.3. At pH values outside this range, the Training the desired corrosion-protecting and friction-reducing Layer the more unsatisfactory the further you go from the specified Area removed.
• component d) 10 to 100 wt .-% of phosphoric acid or whose anions exist. If not phosphoric acid as the only acid of the Group d) is used, the concomitant use of nitric acid or their anions advantageous.
• tannin in the concentration range 50 to 500 mg / l increases the Effect of group b) hydroxycarboxylic acids on the reduction the "metal exposure value" of a subsequent coating. Accordingly, it is preferred that the treatment solution according to the invention additionally Contains tannin. Tannins (compare, for example, Römpp Chemie Lexicon 9th edition 1992, keyword “Tannin”) stands as a group name for a number of natural polyphenols of very diverse compositions, which can be derived from gallic acid. Here are the gallic acid derivatives often esterified with glucose before. In the form of herbal extracts The tannins of different origins represent a well-known group of active ingredients for leather tanning.
• the treatment solution contains, by means of the components of group a), surface-active components which tend to foam, it may be necessary to add defoamers to the treatment baths in the case of strong bath movements, such as for spray systems. Amounts in the range of 50 to 500 mg / l should generally be sufficient.
• suitable defoamers are alkyl polyalkoxy esters. A suitable polyalkoxy ester of this type is available under the trade name Foamaster R C14 from Henkel KGaA, Düsseldorf (Germany).
• a further improvement of the coating, especially with regard to their paintability can be achieved by using the treatment solution additionally water-soluble or water-dispersible organic Add polymers in concentrations from about 100 to about 1000 mg / l.
• these polymers can be selected from h) homopolymers or heteropolymers of ethylene oxide, propylene oxide and / or butylene oxide, i) homopolymers or heteropolymers of acrylic acid, maleic acid and / or derivatives thereof, k) homo- or heteropolymers of vinylphenol and / or vinylphenol derivatives, 1) Homopolymers or heteropolymers of vinyl alcohol and / or vinyl alcohol derivatives. Polymers of the type mentioned are commercially available.
• the polyvinylphenol derivatives of group k) are obtainable by a Mannich reaction from Polyvinylphenol with aldehydes with alkylamines.
• a reaction product of poly (4-vinylphenol) with formaldehyde and 2-alkylamino-1-ethanol is contained in W092 / 07973.
• compositions of the invention have become ready for use Treatment solutions described. It is of course possible to do this Baths by mixing together the individual components in the specified Prepare concentration areas directly on site. For the user such treatment solutions, however, it is cheaper, from a manufacturer to obtain aqueous concentrates of the treatment solutions and these on site by diluting with water to the concentration ranges of the application solutions adjust. Accordingly, the invention also includes aqueous Concentrates of the treatment solutions, which are diluted with water Treatment solutions according to the invention result. It is technical and economically most attractive to adjust the concentrates so that them by diluting them with water in a volume ratio between 1:50 and 1:200 the ready-to-use treatment solutions are obtained can. For example, the concentrate can be adjusted so that it to prepare the ready-to-use treatment solution with water in proportion Must be diluted 1: 100.
• the treatment solution according to the invention preferably comes in one process for the production of cans, in particular beverage cans made of aluminum alloys, for use.
• the preformed cans in the Usually subjected to one or two-stage acidic or alkaline cleaning, which is usually followed by a rinse with tap water.
• the doses are brought in with the treatment solution according to the invention Touch, for example by immersing the cans in the solution or can be done by spraying the cans with the solution.
• the temperature of the treatment solution is between 30 and 60 ° C and in particular 40 to 45 ° C.
• the duration of treatment should be 10 do not fall below sec.
• a treatment duration of more than 120 sec. brings no technical advantage. For example, it is convenient to have one Treatment duration of about 30 seconds to choose.
• the invention encompasses also a method of producing an anti-corrosion, anti-friction and the protective layer on surfaces which improves the paintability made of aluminum or tin and their alloys, characterized in that that the surfaces with an aqueous solution after a or more of claims 1 to 8, which have a temperature in the range of 30 up to 60 ° C, for a period between 10 and 120 seconds in contact brings, which one preferably for the treatment of cans made of aluminum or uses aluminum alloys.
• the invention was tested on aluminum beverage cans with a volume between 330 and 350 ml, as are customary for soft drinks.
• the preformed cans were first cleaned (acidic cleaner Ridoline R 124, Henkel KGaA, Düsseldorf; 54 to 60 ° C, 1 minute) and then rinsed with tap water at room temperature. Thereafter, the surface treatment was carried out with treatment solutions according to the invention and with comparison solutions according to the table with pH values in the range between 2.45 and 2.93 at temperatures between 40 and 45 ° C. for a treatment period of 30 seconds in spraying. This was followed by rinsing with tap water, followed by rinsing with demineralized water, each at room temperature, after which the cans were dried at 150 ° C. for 5 minutes.
• the well water resistance was determined in that the unpainted cans for 30 minutes in a 66 ° C solution of 0.2 g / l Sodium tetraborate decahydrate were dipped, then with fully desalinated Rinsed water and dried at 105 ° C in a drying oven. The can bottoms were then assessed visually for the degree of discoloration. No or a slight discoloration is considered acceptable, a dark or irregular discoloration as unacceptable. Either those with the method variants according to the invention as well as with comparison methods Doses treated according to the prior art passed these Corrosion resistance test.
• the surface friction of the unpainted beverage cans was determined on a tilting table. For this, 3 doses are treated equally used. Two cans are placed side by side on the tilting table arranged so that its longitudinal axis is perpendicular to the tilt axis. A third can with its longitudinal axis is perpendicular to this pair of cans to the tilt axis so that it is about 0.5 cm is shifted in the direction of the tilt axis, whereby it is opposed to the lower cans are placed with the open side in the direction of the tilt axis. The tilting table is then automatically tilted at a constant speed and the angle of inclination ⁇ was found at which the upper box slipped while touching a switch.
• the tangent of the angle of inclination ⁇ , in which the slipping takes place, is called the coefficient of friction.
• 6 used the same treated doses, of which 3 each for an experiment to be chosen. 6 independent measurements with different ones are carried out Combinations of cans. The 6 measurements become the Average determined.
• the treatment solutions according to the invention and the comparison solutions determined according to the prior art coefficient of friction showed no significant differences and were in the range from 0.476 to 0.514.
• the cans connected as electrodes were filled with an electrolyte solution (50.6 g of sodium chloride and 1.19 g of dioctyl sodium sulfosuccinate in 5 l of completely deionized water), into which a metal bracket was immersed as a counter electrode. After applying the voltage, the current was measured in mA after 4 seconds and set as the MEV value. An upper MEV value of 5 mA is specified as the test criterion for beverage cans for soft drinks. The results obtained are entered in the table. The table also contains the number of doses that were measured per treatment solution, the mean MEV value, the maximum observed MEV value and the number of doses at which the specification was exceeded by a maximum MEV value of 5 mA.
• Pretreatment Solutions and Metal Exposure Value (MEV) Basic recipe: 400 mg / l tris (2-hydroxyethyl) tallow ammonium acetate 145 mg / l hexafluorozirconic acid 66 mg / l phosphoric acid 266 mg / l nitric acid 32 mg / l hydrofluoric acid 200 mg / l defoamer (alkyl polyalkoxy ester, Foamaster R C14, Henkel KGaA, Düsseldorf) Additions of sodium gluconate and tannin Trial No.
• MUV Metal Exposure Value

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• Chemical & Material Sciences (AREA)
• General Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Chemical Treatment Of Metals (AREA)
• Paints Or Removers (AREA)
• Application Of Or Painting With Fluid Materials (AREA)
• Preventing Corrosion Or Incrustation Of Metals (AREA)

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• 1994
  • 1994-11-23 DE DE4441710A patent/DE4441710A1/de not_active Withdrawn
• 1995
  • 1995-08-25 TW TW084108884A patent/TW283740B/zh active
  • 1995-11-14 AT AT95940171T patent/ATE178951T1/de not_active IP Right Cessation
  • 1995-11-14 AU AU41719/96A patent/AU698370B2/en not_active Ceased
  • 1995-11-14 JP JP8516528A patent/JPH10509766A/ja active Pending
  • 1995-11-14 EP EP95940171A patent/EP0793738B1/de not_active Expired - Lifetime
  • 1995-11-14 WO PCT/EP1995/004466 patent/WO1996016205A1/de active IP Right Grant
  • 1995-11-14 BR BR9509759A patent/BR9509759A/pt not_active IP Right Cessation
  • 1995-11-14 CA CA002205996A patent/CA2205996A1/en not_active Abandoned
  • 1995-11-14 DE DE59505673T patent/DE59505673D1/de not_active Expired - Fee Related
  • 1995-11-22 AR AR33433095A patent/AR000259A1/es unknown
  • 1995-11-22 TR TR95/01469A patent/TR199501469A2/xx unknown
  • 1995-11-22 ZA ZA959938A patent/ZA959938B/xx unknown

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