EP0925389B1 - Porenfreie beschichtung von metallbehältern - Google Patents

Porenfreie beschichtung von metallbehältern Download PDF

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Publication number
EP0925389B1
EP0925389B1 EP97940152A EP97940152A EP0925389B1 EP 0925389 B1 EP0925389 B1 EP 0925389B1 EP 97940152 A EP97940152 A EP 97940152A EP 97940152 A EP97940152 A EP 97940152A EP 0925389 B1 EP0925389 B1 EP 0925389B1
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EP
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Prior art keywords
coating
acid
weight
epoxy
bis
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EP97940152A
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German (de)
English (en)
French (fr)
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EP0925389A1 (de
Inventor
Klaus Markfort
Thomas BRÜCKEN
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PPG Industries Ohio Inc
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PPG Industries Ohio Inc
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    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D13/00—Electrophoretic coating characterised by the process
    • C25D13/12—Electrophoretic coating characterised by the process characterised by the article coated
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D13/00—Electrophoretic coating characterised by the process
    • C25D13/20—Pretreatment

Definitions

  • the present invention relates to a method for coating of Metal containers, in particular those intended for the storage of Food and drinks are suitable.
  • the used inner can paints must be characterized by a high resistance to hydrolysis and chemicals identify, e.g. in the storage of predominantly acidic contents to be consistent.
  • the tinned interior paints also have to be strict comply with food law and they may not Hydrolysis reactions under pasteurization conditions and longer have permanent storage.
  • Electrocoating is basically the anodic over the cathodic dip coating preferred because cathodically deposited Films mostly contain amino groups and thus in contact with acidic Filling goods can be less resistant.
  • Both the Electrocoating as well as the spray painting have each individual advantages and disadvantages. But they both have in common Problem that after a one-time coating process and subsequent drying of the lacquer layer latter one unacceptable has high porosity. During the drying process are in the Lack Mrs holes ("pores") emerged, the underlying Release metal. The presence of these pores manifests itself in the Laboratory test in an electrical conductivity between the metal Can body and an electrolyte inside the can. Of course it is for the storage of food unacceptable if such pores are present in the paint.
  • the present invention has the object, on the other hand, a method of coating metal containers for storage to develop foods in which the porosity of Coating is reduced, so that the container food grade with, at the same time, the specific paint weight override known coatings of the same properties is reduced.
  • the inventive method is carried out such that after application of the base coat, it is dried. If liquid paints are used for the base coat, too a wet-on-wet job is possible. "Baking") understood that the paint layer by evaporation of Physically dries and possibly through existing solvents Crosslinking chemically cured.
  • Produce food cans that do not increase the Lackoptionurchlage showed, but where the porosity to 1/20 of original value (measured with conductivity tests) reduced could be.
  • the method is especially for two- and three-piece beverage and food cans suitable.
  • inventive method can for the undercoating Electrocoating paint, spray paint, Powder coating or powder coating dispersions (preferably aqueous dispersions).
  • Electrocoating paints for the base coat and the second coat are Electrocoating paints for the base coat and the second coat:
  • Electrophoretically depositable coating agents for Internal coating of metal containers used for storage of Food and drinks are suitable (so-called “food contacting Coatings "), are known in large numbers.
  • electrophoretically depositable tinned interior protective lacquers are known, for example, from EP-A-6334 and EP-A-6336.
  • Other known tinned internal protective lacquers suitable for electrophoretic application are based on polymer blends obtained by free-radical copolymerization of partially carboxyl-containing ethylenically unsaturated monomers in the presence of an epoxy resin and peroxidic initiators (see US 4,212,781, US 4,308,185, WO 88/1287).
  • Further electrophoretically depositable internal tinting coatings are described, for example, in DE-A-28 05 657, DE-A 36 01 560, US 4,476,263 and EP-A-216,337.
  • electrocoating paints are known in which the aqueous depositable coating composition 0.01 to 10% by weight, preferably 0.5 to 3 wt .-%, based on the solids of the Coating composition, in the range of 60 ° C to 100 ° C in the molten state containing wax.
  • the used Coatings still pigments, fillers and other auxiliary and Add additives in each case usual amounts.
  • the pigments and / or fillers are preferably used in amounts of from 25 to 35 wt .-%, based on the total weight of the coating composition, used.
  • pigments is titanium dioxide, for example those among the Commercially available Titanium Rutil RN 59, RCT 60, R 900 and RDI-S Products.
  • fillers are barium sulfate, silica, potassium carbonate as well To call talcum by way of example.
  • the coating compositions preferably contain 0.01 to 5.0% by weight, based on the total weight of the coating composition, other auxiliaries and additives, such as Plasticizers, stabilizers, Wetting agents, dispersing aids, catalysts and surface-active Additives.
  • auxiliaries and additives such as Plasticizers, stabilizers, Wetting agents, dispersing aids, catalysts and surface-active Additives.
  • the bath solids of electrophoretically depositable Coating agent is in the range of 5 to 30 wt .-%, preferably in the range of 8 to 20 wt .-%.
  • lacquers are described in EP 118 756.
  • both anionic and cationic resins can be used be used, the anionic for acidic, the cationic for basic fillers are preferred.
  • the anionic resins like maleinated or acrylated butadienals, maleated natural oils, carboxyl group-containing epoxy resin esters and acrylate resins, Acrylic epoxy resins, unmodified or fatty acid-modified polyesters have an acid number of 30 to 180, especially between 40 and 80, and are with ammonia, amines or amino alcohols at least partially neutralized. Preference is given to volatile amines, thus with the desired short burn-in times of 10 sec. to 300 sec. be removed as completely as possible from the film. Especially preferred is ammonia.
  • crosslinking takes place either oxidatively over unsaturated Double bonds or by thermal reaction with appropriate Crosslinking agents such as phenolic resins, amine-formaldehyde resins or blocked polyisocyanates.
  • appropriate Crosslinking agents such as phenolic resins, amine-formaldehyde resins or blocked polyisocyanates.
  • phenolic resins phenolic resins
  • amine-formaldehyde resins amine-formaldehyde resins or blocked polyisocyanates.
  • white paint coatings Alien or self-crosslinking acrylate resins are preferred.
  • Coating with clearcoats become foreign or self-crosslinking Acrylic resins, acrylated or maleated epoxy esters or epoxy acrylates prefers.
  • the cationic resins such as butadienol-aminoalkylimide Mannich bases of phenolic resins, amino group-containing acrylate resins or amino-epoxy resins have an amine number of 30 to 120 mg KOH / g solid resin, preferably before 50 to 90 and are organic Monocarboxylic acids such as carbonic acid, formic acid, acetic acid, Lactic acid etc. at least partially neutralized.
  • Crosslinking agents are used except unsaturated double bonds preferably blocked polyisocyanates or resins which contain esterification ester groups.
  • the binders are annealed with the neutralizing agents and optionally in the presence of solvents with deionized or diluted in distilled water.
  • solvents are primary, secondary and / or tertiary alcohols, ethylene or propylene glycol mono or -diether, diacetone alcohol or even small amounts of non water-dilutable solvents such as gasoline hydrocarbon.
  • the aim is a lowest possible content of solvents, advantageously below 15 wt.% And preferably below 5 wt.%, Because with increasing solvent content worsens the wraparound.
  • the bath solids is generally between 5 and 30 wt.%, in particular above 8 and below 20 wt.%. With increasing solid becomes increases the bath conductivity and the precipitation equivalent (ampere sec / g) reduced, whereby the Umgriff can be increased. By the high concentration of layer-forming ions is thereby the Sheet resistance by a maximum.
  • the bath temperature is between 20 and 35 ° C. With falling temperature increases the Umgriff. Temperatures below 20 ° C are uneconomic, because the heat generated by the EC coating through much Cooling water must be removed again. Temperatures above 35 ° C complicate the bath management, because too much solvent evaporates and Hydrolysis phenomena on the binder system fluctuations in the generate electrical data.
  • the coating agent may additionally conventional paint aids such Catalysts, leveling agents, antifoaming agents, lubricants, etc. included.
  • paint aids such as Catalysts, leveling agents, antifoaming agents, lubricants, etc. included.
  • such additives should be selected which are added with water the pH of the bath no disturbing reactions, none entrain disturbing foreign ions and during prolonged standing not in precipitate form.
  • the binders can be used pigmented or unpigmented.
  • pigments and fillers such materials can be used due to their small particle size below 10 microns, especially below 5 microns, can be dispersed in the paint stably and in the Stir again. You must not disturbing foreign ions and may not contain water or the neutralizing agent react chemically.
  • the pigmentation can be both white and colored. Whiteness prefers. With additional incorporation of interference pigments it is possible, metal effect finishes with aluminum, silver, brass, Copper, gold effects, etc. to achieve.
  • the pigments like titanium dioxide are ground in a concentrated millbase and then with further binder to a pigment-to-binder ratio of about 0.1 set to 1 to 0.7 to 1.
  • Resins which are electrodepositable at the cathode are e.g. in the U.S. Patent 3,617,458. It is cross-linkable Coating mass deposited on the cathode. These Coating compositions are derived from an unsaturated polymer which Amine groups and carboxyl groups, and an epoxidized Material off.
  • aqueous dispersions which are allow the cathode to be electrically deposited and made of an epoxy resin ester, Water and tertiary amino salts exist.
  • the Epoxiester is that Reaction product of glycidyl polyether and a basic unsaturated oleic acid.
  • the amine salt is the reaction product of one aliphatic carboxylic acid and a tertiary amine.
  • Epoxy and polyurethane based binders for use with Binder dispersions and pigment pastes are also known in numerous embodiments known. For example, be on the DE-27 01 002, EP-A-261 385, EP-A-004 090 and DE-PS 36 30 667.
  • the preparation of the base coating in the inventive Procedure can also be carried out with all spray paints, as they are in the field of internal coating of unilaterally open packaging, In particular, beverage cans, are common.
  • An inventively suitable spray paint consists of a self-emulsifying Epoxy ester copolymer mixture.
  • This one is in one Process in which a solvent-soluble, carboxyl group-containing polymer is esterified with an epoxy resin.
  • the epoxy resin is a mixture containing aromatic Polyethers with epoxy groups, wherein at least 5% of the aromatic Polyethers are composed of diepoxide.
  • the mixture of aromatic polyether makes up about 40% of the total solids content of the resin and provides the epoxy groups that are related to to the carboxyl groups in a stoichiometric ratio of 1: 2 to 1:20.
  • the esterification takes place in an organic Solvents in the presence of more than 2% (based on the Total weight of the reaction partners of the esterification) of an aminic Esterification catalyst instead.
  • the temperature is sufficient increased to the reaction of the epoxy groups with the carboxyl groups advancing until the epoxy groups substantially and at least a portion of the carboxyl groups in the resulting polymer-epoxy hydroxy ester product with a base have reacted to the reaction product self-emulsifying in water close.
  • a spray paint according to the invention is also an ungelled hydroxy-ester copolymer composition suitable, essentially free of Is epoxy groups, and which is the hydroxy ester product of an acidic Contains copolymers with epoxy resin.
  • the epoxy resin is one Mixture containing at least 5 wt .-% of an aromatic Polyether, which carries two epoxy groups and in the reaction with the acidic copolymer is consumed.
  • the acidic copolymer is a dissolved one Containing copolymer of monoethylenically unsaturated monomers at least about 20% (based on the total weight of the monomers) a monoethylenically unsaturated carboxylic acid.
  • the epoxy resin mixture makes up at least 40% of the total solids content of the Resin and provides the epoxy groups with respect to the carboxyl groups in a stoichiometric ratio of 1: 2 present until 1:20. At least a part of the carboxyl groups in the resulting copolymer epoxy resin hydroxy ester product reacts with a base to self-emulsify the reaction product in water do.
  • Another useful aqueous spray paint contains the neutralized, water-dispersible ionic polymer from the reaction of a An epoxy resin with an acidic polymer and further another resin, the not necessarily self-dispersible in water.
  • the other Resin is supplied either preformed at any stage, or it is in situ either before or after dispersing the ionic Epoxy Acid Polymer Product in Water Prepares in Presence of the epoxy resin esterified with the acidic polymer.
  • the Epoxy acid polymer product behaves as a polymeric surfactant, even that normally does not self-dispersible second polymer in a stable aqueous dispersion can hold.
  • the following known spray paint can in the inventive Plant to be used.
  • This paint is obtained by Additon reaction of a monomer, e.g. Styrene, in one Reaction medium containing a modified epoxy resin.
  • the Epoxy resin is made by combining part of its epoxy groups with epoxy-reactive groups of an ethylenically unsaturated monomer modified as well as by the reaction of other of its epoxy groups with a tertiary amine and a preformed addition polymer, which carboxyl groups to form an ionic resin compound contains enough carboxyl groups to the paint in neutralized form self-dispersible in water.
  • a coating resin composition in the form of an aqueous Dispersion applicable containing an aromatic epoxy resin component and an acrylic resin component consisting of acrylic acid or Methacrylic acid and a monoethylenic monomer copolymerized and having excess carboxyl groups, as well as ammonia or an amine for partial neutralization.
  • the pH is between 5 and 11.
  • the epoxy resin component and the Acrylic resin components are present in the form of a partial reaction product (A) an alkali-neutralizable acrylic resin having a number average Molecular weight of 5000 to 100,000, which by copolymerization from 12 to 50% by weight of acrylic acid or methacrylic acid having from 50 to 88 Wt .-% styrene, methyl styrene, vinyl toluene and alkyl esters of acrylic acid and / or methacrylic acid having 1 to 8 carbon atoms in the alkyl group and (B) an aromatic epoxy resin with an average of 1.1 to 2.0 epoxy groups per molecule and one number average molecular weight of at least 1400, except a coating composition containing a nonionic surfactant Medium.
  • A an alkali-neutralizable acrylic resin having a number average Molecular weight of 5000 to 100,000, which by copolymerization from 12 to 50% by weight of acrylic acid or methacrylic acid having from 50 to 88 Wt .-% sty
  • the components (I) and (II) are in one Amount ratio (I): (II) from 0.1 to 2 included.
  • aqueous tin inner coatings are available Acrylate resin base known, the waxes, e.g. Canauba wax, as additives can contain.
  • the paints are not electrophoretically applied, but by means of spray painting, dip painting, rolling or Coating applied.
  • Powder coating dispersions preferably Powder clearcoat dispersions used.
  • aqueous Dispersions are particularly preferred.
  • the powder coatings which can be used according to the invention are characterized thereby out. that coatings with only a very small layer thickness of ⁇ 15 to those required by can manufacturers for interior coatings Have properties. Furthermore, these coatings are characterized due to a good adhesion, high flexibility and a good pasteurization and Sterilization resistance.
  • the epoxy resins used in the powder coatings are preferably solid epoxy resins having an epoxide equivalent weight of 300 to 5500.
  • Suitable as component A are aromatic, aliphatic and / or cycloaliphatic epoxy resins.
  • Aromatic epoxy resins based on bisphenol A and / or bisphenol F and / or novolak-type epoxy resins are preferably used.
  • Epoxide resins based on bisphenol A or bisphenol F used with particular preference have an epoxide equivalent weight of 500 to 2,000. Particular preference is given to using novolak-type epoxy resins having an epoxide equivalent weight of 500 to 1000.
  • Epoxy resins based on bisphenol-A or bisphenol-F generally have a functionality of at most 2 and epoxy resins of the novolak type have a functionality of generally at least 2.
  • the epoxy resins based on bisphenol-A or bisphenol-F can be brought to a functionality of more than 2 by branching, for example by means of trimethylolpropane, glycerol, pentaerythritol or other branching reagents.
  • epoxy resins such as e.g. Alkylenglykoldiglycidylether or their branched secondary products, with Alkylene glycols flexibilized epoxy resins based on bisphenol A or -F etc. be used.
  • Alkylene glycols flexibilized epoxy resins based on bisphenol A or -F etc.
  • Suitable epoxy resins are, for example, under the name below commercially available products: Epikote® 154, 1001, 1002, 1055, 1004, 100.7, 1009, 3003-4F-10 from Shell-Chemie, XZ 86 795 and DER® 664, 667, 669, 662, 642U and 672U from Dow and Araldit®, GT 6064, GT 7072, GT 7203, GT 7004, GT 7304, GT 7097 and GT 7220 the Company Ciba Geigy.
  • epoxy group-containing polyacrylate resins suitable by Copolymerization of at least one ethylenically unsaturated Monomer containing at least one epoxy group in the molecule, with at least one further ethylenically unsaturated monomer which contains no epoxy group in the molecule can be produced, wherein at least one of the monomers is an ester of acrylic acid or methacrylic acid.
  • epoxy group-containing polyacrylate resins are known, for example EP-A-299 420, DE-B-22 14 650, DE-B-27 49 576, US-A-4,091,048 and US-A-3,781,379.
  • alkyl esters of acrylic and Methacrylic acid containing 1 to 20 carbon atoms in the alkyl radical in particular methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, Butyl acrylate, butyl methacrylate, 2-ethylhexyl acrylate and 2-ethylhexyl methacrylate called.
  • ethylenic unsaturated monomers containing no epoxy groups in the molecule are acid amides, e.g.
  • Acrylic acid and methacrylamide vinyl aromatic compounds such as styrene, methyl styrene and vinyl toluene, Nitriles, such as acrylonitrile and methacrylonitrile, vinyl and vinylidene halides, such as vinyl chloride and vinylidene fluoride, vinyl esters, e.g. Vinyl acetate and hydroxyl group-containing monomers, such as e.g. Hydroxyethyl acrylate and Hydroxyethyl methacrylate.
  • vinyl aromatic compounds such as styrene, methyl styrene and vinyl toluene
  • Nitriles such as acrylonitrile and methacrylonitrile
  • vinyl and vinylidene halides such as vinyl chloride and vinylidene fluoride
  • vinyl esters e.g. Vinyl acetate and hydroxyl group-containing monomers, such as e.g. Hydroxyethyl acrylate and Hydroxyethyl methacrylate.
  • the binder may in particular vinyl aromatic compounds contain, preferably styrene. To the risk of cracking too limit, however, the content is not more than 35 wt .-%. Prefers be 10 to 25 wt .-%.
  • the epoxy group-containing polyacrylate resin usually has one Epoxy equivalent weight of 400 to 2500, preferably 420 to 700, a number average molecular weight (gel permeation chromatography determined using a polystyrene standard) from 2,000 to 20,000, preferably from 3,000 to 10,000, and a glass transition temperature (TG) from 30 to 80, preferably from 40 to 70, more preferably from 40 to 60 ° C (measured with the aid of Differential scanning calorimetry (DSC)). Very particularly preferred will be about 50 ° C. Mixtures of two or three can also be used more acrylate resins are coming.
  • the epoxy group-containing polyacrylate resin may be generally good known methods are prepared by polymerization.
  • powder clearcoats are suitable which have an epoxifunctional Crosslinker and an acid functional binder included.
  • acid-functional binder are, for example, acidic Polyacrylate resins suitable by copolymerization of at least an ethylenically unsaturated monomer containing at least one Contains acid group in the molecule, with at least one other ethylenic unsaturated monomer containing no acid group in the molecule, can be produced.
  • the epoxy group-containing binder or the epoxy group-containing Crosslinker and the carboxyl or the binder are usually used in such an amount that per equivalent of epoxy groups 0.5 to 1.5, preferably 0.75 to 1.25 equivalents of carboxyl groups available.
  • the amount of carboxyl groups present can by Titration be determined with an alcoholic KOH solution.
  • the epoxy resin component A is usually in the powder coatings in from 29 to 80% by weight, preferably from 39 to 60% by weight, preferably from 39 to 60 wt .-%, each based on the total weight of the powder coating used.
  • Component I contains a hardener component B, which usually in an amount of 10 to 50% by weight, preferably 15 to 40 wt .-%, each based on the total weight of the powder coating. is used.
  • Suitable hardener component B are all solid compounds with more as a phenolic OH group, preferably from 1.8 to 4 and especially preferably ⁇ 3 phenolic OH groups per molecule and one hydroxyl equivalent weight, based on OH groups of 100 to 500, preferably 200 to 300.
  • Preferred hardeners are those based on bisphenol A and / or Bisphenol-F used.
  • the hardener is particularly preferred Condensation product of the diglycidyl ether of bisphenol-A or Bisphenol-F with bisphenol A or bisphenol-F, in particular the Condensation product having a phenolic hydroxyl group equivalent equivalent weight from 220 to 280.
  • These Condensation products are usually prepared by reacting from i.a. Excess bisphenol with a bisphenol diglycidyl ether in Presence of a suitable catalyst.
  • This is preferred Condensation product prepared by reacting the diglydidyl ether with the bisphenol in a weight ratio of 0.5 to 2.
  • This hardener on the basis of these condensation products of bisphenol diglycidyl ether with a bisphenol generally have a functionality of a maximum of 2, wherein by using branching reagents In turn, higher functionality can be set.
  • suitable hardeners are the reaction products of Bisphenols with novolak type epoxy resins. These are preferred Hardener by reacting the epoxy resin with the bisphenol in Weight ratio of 0.5 to 2 in the presence of a suitable Catalyst obtained.
  • Suitable examples are the phenolic hardener described in DE-PS 23 12 409 in column 5, line 2 to column 6, line 55. These polyphenols correspond to the following general formulas in which A is a divalent hydrocarbon radical having 1-6 C atoms or the radicals X is a hydrogen or alkyl having 1 to 4 C atoms n, an average value of 1 to 9, preferably 2 to 7 and y is a value of 0 or 1 accepts.
  • Hardener and / or flexibilized hardener suitable. Further, you can also Mixtures of different of the mentioned hardeners are used. In this case, FDA-approved hardeners are preferably used.
  • crosslinkers (component b) are also carboxylic acids, in particular saturated, straight-chain, aliphatic dicarboxylic acids having 3 to 20 C atoms suitable in the molecule. Very particular preference is given to dodecane-1,12-dicarboxylic acid used.
  • To modify the properties of finished powder clearcoats may optionally have other Carboxyl-containing crosslinkers are used.
  • These are saturated branched or unsaturated straight-chain di- and Polycarboxylic acids and polymers with carboxyl groups called.
  • the polyesters used in the powder coatings have an acid number of 25 to 120 mg KOH / g, preferably 30 to 90 mg KOH / g and particularly preferably 60 to 90 mg KOH / g and an OH number of at least 10 mg KOH / g, preferably at least 15 mg KOH / g and preferably less than or equal to 30 mg KOH / g.
  • Preference is given to polyesters used with a functionality ⁇ 2.
  • the number average Molecular weights of the polyesters are generally between 1000 and 10000, preferably between 1500 and 5000. Preference is given to FDA-approved (FDA: Food and Drug Administration) used polyester.
  • the carboxyl and hydroxyl-containing polyesters are included by the usual methods (see, e.g., Houben Weyl, Methoden der Organic Chemistry, 4th Edition, Volume 14/2, Georg Thieme Verlag, Stuttgart 1961) can be produced.
  • the carboxylic acid component for the preparation of the polyester aliphatic, cycloaliphatic and aromatic di- and Polycarboxylic acids e.g. Phthalic acid, terephthalic acid. Isophthalic acid, trimellitic acid, pyromellitic acid, adipic acid, succinic acid. Glutaric acid, pimelic acid, suberic acid, azelaic acid, Sebacic acid, etc.
  • the acids can also be in the form of their esterifiable derivatives (e.g., anhydrides) or theirs transesterifiable derivatives (e.g., dimethyl esters).
  • polyesters are commonly used di- and / or polyols, e.g. Ethylene glycol, 1,2-propanediol and 1,3-butanediol, diethylene glycol, Triethylene glycol, tetraethylene glycol, 1,6-hexanediol, neopentyl glycol, 1,4-dimethylolcyclohexane, Glycerol, trimethylolethane, trimethylolpropane, Pentaerythritol, ditrimethylolpropane, diglycerol, and the like Polyester can be used individually or as a mixture of different Polyester can be used.
  • Ethylene glycol, 1,2-propanediol and 1,3-butanediol diethylene glycol
  • Triethylene glycol tetraethylene glycol
  • 1,6-hexanediol 1,6-hexanediol
  • neopentyl glycol 1,4-di
  • the solid powder coatings may contain one or more suitable ones Catalysts for epoxy resin curing.
  • Suitable catalysts are phosphonium salts of organic or inorganic acids, quaternary ammonium compounds amines, imidazole and imidazole derivatives.
  • the catalysts are generally in proportions of in an amount from 0.001 to 5.0% by weight.
  • the areas are however, at 0.001 wt% to about 2 wt%, more preferably from 0.05 to 2.0 wt .-%, each based on the total weight of Epoxy resin and the crosslinking agent.
  • Suitable phosphonium catalysts are Ethyltriphenylphosphonium iodide, ethyltriphenylphosphonium chloride, Ethyltriphenylphosphonium thiocyanate, ethyltriphenylphosphonium acetate-acetic acid complex, Tetrabutylphosphonium iodide, tetrabutylphosphonium bromide and tetrabutylphosphonium acetate-acetic acid complex.
  • These and other suitable phosphonium catalysts are e.g. described in U.S. Patent 3,477,990 and U.S. Patent 3,341,580.
  • Suitable imidazole catalysts are, for example, 2-styrylimidazole, 1-benzyl-2-methylimidazole, 2-methylimidazole and 2-butylimidazole. These and other imidazole catalysts are e.g. described in the Belgian Patent No. 756,693.
  • the catalyst may also be a quinoline derivative, such as for example, described in EP-B-10805. Also possible primary, secondary or tertiary aminophenol, Aluminum acetylacetonate or toluenesulfonic acid salt or a mixture from various of the mentioned catalysts.
  • the commercially available hydroxyl-containing hardener already a curing catalyst.
  • Examples of such commercial hydroxyl-containing hardener are preferably used under the following names in the Commercially available products: D.E.H.R 81, D.E.H.R 82 and D.E.H.R 84 the company Dow, hardener XB 3082 of the company Ciba Geigy and Epikure® 169 and 171 of Shell-Chemie.
  • solid powder coatings may still aid and additives included.
  • leveling agents include leveling agents, Antioxidants, UV absorbers, radical scavengers, anti-freeze and Degassing agents, such as benzoin.
  • the solid powder coatings can still 0 to 55 wt .-%, preferably 15 to 25 wt .-%, fillers. Preference is given to FDA-approved Fillers used.
  • inorganic Fillers for example, titanium dioxide, such as titanium dioxide.
  • the components described for the powder coating come only insofar to use, as this according to the respective legal regulations is permissible.
  • a binder are accordingly preferably used FDA-approved epoxy resins.
  • the preparation of the solid powder coatings is carried out by known methods (see, for example, product information of BASF Lacke + Maschinen AG, "Powder coatings", 1990) by homogenizing and dispersing, For example, by means of an extruder, screw kneader, etc., After Production of the powder coatings, these are by grinding and optionally by sifting and sieving for dispersion prepared.
  • the powder can then by wet grinding or through Stirring dry powder powder coating the aqueous Puiverklarlackdispersion be prepared. Particularly preferred the wet grinding.
  • Suitable powder coating dispersions can be prepared by an aqueous Dispersion of a powder coating, preferably a powder clearcoat with a glass transition temperature of 20 to 90 ° C, a viscosity of 10 to 1000 mPas and a solids content of 10 to 50%, a grinding process is subjected to maintenance at a temperature of 0 to 60 ° C.
  • aqueous powder coating dispersions on the basis the described component I is this in a component II dispersed.
  • the latter preferably consists of an aqueous Dispersion of catalysts, excipients, antifoams, antioxidants, Wetting agents, UV absorbers, radical scavengers, biocides, Water retention agents small amounts of solvents and / or Dispersing aids, preferably carboxy-functional dispersants.
  • hydrophobic groups used are long-chain alkyl radicals, such as, for example, dodecyl, hexadecyl or octadecyl radicals, or alkaryl radicals, for example octylphenyl or nonylphenyl radicals.
  • hydrophilic skeletons preferably polyacrylates, cellulose ethers or particularly preferably polyurethanes are used which contain the hydrophobic groups as polymer building blocks.
  • hydrophilic skeletons polyurethanes the Contain polyether chains as building blocks, preferably from Polyethylene oxide.
  • polyether polyurethanes serve the di- and or Polyisocyanates, preferably aliphatic diisocyanates, especially preferably alkyl-substituted 1,6-hexamethylene diisocyanate, if appropriate, for linking the hydroxyl groups Polyether building blocks underneath and for linking the polyether building blocks with the hydrophobic end-group building blocks, the For example, monofunctional alcohols and / or amines with the already be mentioned long-chain alkyl radicals or aralkyl radicals.
  • the pH to 4.0 to 7.0 preferably 5.5 adjusted to 6.5 and filtered.
  • the mean grain size is between 1 and 25 microns, preferably less than 20 microns, more preferably from 3 to 10 microns.
  • the solids content of the aqueous powder clearcoat dispersion is between 15 and 50%.
  • the dispersion can before or after the wet grinding or the Enter the dry powder coating in the water 0 to 5% by weight of a Defoamer mixture, an ammonium and / or alkali metal salt, a carboxy-functional or non-ionic dispersing assistant, Wetting agent and / or thickener mixture and the other additives be added.
  • a Defoamer mixture an ammonium and / or alkali metal salt, a carboxy-functional or non-ionic dispersing assistant, Wetting agent and / or thickener mixture and the other additives be added.
  • defoamers, Dispersing aid, wetting and / or thickening agent first in water dispersed. Then small portions of the powder clearcoat stirred. Then defoamers, dispersion auxiliaries, Thickening and wetting agents dispersed. Finally are again stirred in small portions of powder clearcoats.
  • the adjustment of the pH preferably takes place with ammonia or Amines.
  • the pH may initially increase that a strong basic dispersion is formed. However, the pH drops within several Hours or days back to the above values.
  • the base coat of metal containers can also be powder coated respectively. Preferred are those which 0.05 to 5 wt .-%, preferably 0.5 to 1.5% by weight of aliphatic polyvinyl ethers as Contain leveling agents.
  • the powder coating may consist of epoxy resins, too epoxidized novolaks, from crosslinking agents, preferably phenolic or amine hardeners or bicyclic guanidines, Catalysts, fillers and, if necessary, auxiliaries and additives.
  • the powder coatings used according to the invention preferably contain Epoxy resins, phenolic crosslinkers, catalysts, auxiliaries as well as aids and powder-typical additives, flow aids.
  • Suitable epoxy resins are all solid epoxy resins with a Epoxy equivalent weight between 400 and 3,000, preferably 600 to 2000. These are mainly epoxy resins based on Bisphenol A and bisphenol F. Preference is given to expoxidized Novolak. These preferably have an epoxide equivalent weight from 500 to 1,000.
  • the epoxy resins based on bisphenol A and bisphenol F have in general a functionality of less than 2, the epoxidized Novolak resins have a functionality greater than 2.
  • epoxidized in the powder coatings of the invention Novolac resins with an average functionality in the range of 2.4 to 2.8 and having an epoxide equivalent weight in the range of 600 to 850.
  • the epoxidized novolac resins are the phenolic Hydroxyl groups etherified with alkyl, acrylic or similar groups. By reaction of the phenolic hydroxyl groups with Epichlorohydrides are introduced into the molecule epoxy groups. Starting with novolaks, the so-called epoxide novolac forms.
  • Epoxidized novolaks are structurally related to bisphenol A resins.
  • Epoxidized novolak resins can be prepared by Epoxidation of novolaks, e.g. from 3 to 4 phenol cores, which are connected by methylene bridges.
  • Novolac resins can also alkyl substituted phenols, which with Formaldehyde can be used.
  • Suitable epoxy resins are, for example, the products available under the following names: Epikote 1004, 1055, 3003, 3004, 2017 from Shell-Chemie, DER 640, 671, 662, 663U, 664, 667 from Dow and Araldit GT 6063, 6064, 6084, 6097, 7004, 7220, 7225 from Ciba Geigy.
  • epoxy group-containing polyacrylate resins suitable by Copolymerization of at least one ethylenically unsaturated Monomer containing at least one epoxide group in the molecule, with at least one further ethylenically unsaturated monomer which contains no epoxide group in the molecule, can be produced, wherein at least one of the monomers is an ester of acrylic acid or Methacrylic acid is.
  • Epoxide group-containing polyacrylate resins are known (see, for example, EP-A-299 420, DE-B-22 14 650, DE-B-27 49 576, US-A-4, 091.048 and US-A-3, 781, 379).
  • ethylenically unsaturated monomers containing at least contain an epoxide group in the molecule are glycidyl acrylate, Called glycidyl methacrylate and allyl glycidyl ether.
  • alkyl esters of acrylic and Methacrylic acid containing 1 to 20 carbon atoms in the alkyl radical in particular methyl acrylate, methyl methacrylate, ethyl acrylate, Ethyl methacrylate, butyl acrylate, butyl methyl acrylate, 2-ethylhexyl acrylate and Called 2-ethylhexyl methacrylate.
  • ethylenic unsaturated monomers containing no epoxide groups in the molecule are acids, e.g. Acrylic acid and methacrylic acid. Acid amides, like z.
  • B acrylic acid and methacrylamide, vinyl aromatic compounds, such as styrene, methylstyrene and vinyltoluene, nitriles such as acrylonitrile and methacrylonitrile, vinyl and vinylidene halides such as vinyl chloride and Vinylidene fluoride, vinyl esters, e.g. Vinyl acetate and hydroxyl groups Monomers, e.g. Hydroxyethyl acrylate and hydroxyethyl methacrylate.
  • vinyl aromatic compounds such as styrene, methylstyrene and vinyltoluene
  • nitriles such as acrylonitrile and methacrylonitrile
  • vinyl and vinylidene halides such as vinyl chloride and Vinylidene fluoride
  • vinyl esters e.g. Vinyl acetate and hydroxyl groups
  • Monomers e.g. Hydroxyethyl acrylate and hydroxyethyl methacrylate.
  • the epoxide group-containing polyacrylate resin usually has one Epoxy equivalent weight of 400 to 2,500, preferably 500 to 1,500, more preferably 600 to 1,200, a number average molecular weight (gel permeation chromatography using a Polystyrene standards) of from 1,000 to 15,000, preferably from From 1,200 to 7,000, more preferably from 1,500 to 5,000, and one Glass transition temperature (TG) from 30 to 80, preferably from 40 to 70. more preferably from 50 to 70 ° C (measured with the aid of differential scanning calometry (DSC)).
  • Epoxy equivalent weight 400 to 2,500, preferably 500 to 1,500, more preferably 600 to 1,200
  • a number average molecular weight gel permeation chromatography using a Polystyrene standards
  • TG Glass transition temperature
  • DSC differential scanning calometry
  • the epoxide group-containing polyacrylate can after generally good known methods prepared by free-radical polymerization become.
  • Suitable hardeners for the epoxy group-containing polyacrylate resin For example, polyanhydrides of polycarboxylic acids or of Mixtures of polycarboxylic acids, in particular polyanhydrides of Dicarboxylic acids or mixtures of dicarboxylic acids.
  • Such polyanhydrides can be prepared by the polycarboxylic acid or the mixture of polycarboxylic acids is removed from water, wherein each reacted two carboxyl groups to an anhydride group become. Such manufacturing methods are well known and need therefore not be explained in detail.
  • Powder paint phenolic or aminic hardener For curing the epoxy resins of the invention Powder paint phenolic or aminic hardener. To be used can also bicyclic guanidines.
  • any phenolic resin can be used, as long as it is required for reactivity methylol functionality having.
  • Preferred phenolic resins are under alkaline conditions prepared reaction products of phenol, substituted phenols and Bisphenol A with formaldehyde. Under such conditions, the Methylol proceed either ortho or para with the aromatic Ring linked.
  • Particularly preferred according to the present Invention as a phenolic crosslinking agent hydroxyl-containing Bisphenol A or bisphenol F resins with a Hydroxy equivalent weight in the range of 180 to 600, especially preferably in the range of 180 to 300, used.
  • Such phenolic Crosslinking agents are prepared by reacting bisphenol-A or bisphenol-F with glycidyl group-containing components, e.g.
  • phenolic crosslinking agents are available, for example, under the trade name DEH 81, DEH 82 and DEH 87 of the company Dow DX 171 of Shell-Chemie and XB 3082 of the company Ciba Geigy.
  • the epoxy resins and the phenolic crosslinking agents are in used such a ratio that the number of epoxy groups to the number of phenolic OH groups in about 1: 1.
  • the powder coatings contain one or more suitable catalysts for epoxy resin curing.
  • Suitable catalysts are Phosphonium salts of organic or inorganic acids, imidazole and Imidazole derivatives, quaternary ammonium compounds and amines.
  • the Catalysts are generally added in proportions of 0.001% by weight about 10 wt .-%, based on the total weight of the epoxy resin and of the phenolic crosslinking agent.
  • Suitable phosphonium salt catalysts are Ethyltriphenylphosphonium iodide, ethyltriphenylphosphonium chloride, Ethyltriphenylphosphonium thiocyanate, ethyltriphenylphosphonium acetate-acetic acid complex, Tetrabutylphosphonium iodide, tetrabutylphosphonium bromide and tetrabutylphosphonium acetate-acetic acid complex.
  • Ethyltriphenylphosphonium iodide ethyltriphenylphosphonium chloride
  • Ethyltriphenylphosphonium thiocyanate ethyltriphenylphosphonium acetate-acetic acid complex
  • Tetrabutylphosphonium iodide Tetrabutylphosphonium iodide
  • tetrabutylphosphonium bromide and tetrabutylphosphonium acetate
  • Suitable imidazole catalysts are, for example, 2-styrylimidazole, 1-benzyl-2-methylimidazole, 2-methylimidazole and 2-butylimidazole. These and other imidazole catalysts are e.g. described in the Belgian Patent No. 756,693.
  • the powder coatings contain 50 to 90%, preferably 60 to 80 wt .-% Binder and 10 to 50 wt .-%, preferably 20 to 40 wt .-% fillers.
  • Suitable fillers are glycidyl-functionalized crystalline Silicic acid modifications into consideration. Usually they are in the said range of 10 to 50 wt .-%, based on the Total weight of the powder coating used. In some cases, however also filler contents of more than 50 wt .-% possible.
  • Crystalline silica modifications include quartz, cristobalite, tridymite, keatite, stishovite, melanophlogite, coesite and fibrous silica.
  • the crystalline silica modifications are glycidyl functionalized, with glycidyl group functionalization achieved by surface treatment. These are, for example, quartz, cristobalite and fused silica based silica modifications prepared by treating the crystalline silica modifications with epoxysilanes.
  • the glycidyl-functionalized silicic acid modifications are available on the market for example under the name Silbond R 600 EST and Silbond R 6000 EST (manufacturer: Quarzwerke GmbH) and are prepared by reacting crystalline silica modifications with epoxy silanes.
  • the powder coatings contain 10 to 40 wt .-%, based on the total weight of the powder coating, on glycidylgrppenfunktionalinstrumenten crystalline silicic acid modifications.
  • the powder coatings may contain other inorganic fillers, For example, titanium oxide, barium sulfate and silicate-based fillers such as e.g. Talc, kaolin, magnesium. Aluminum silicates, mica and contain similar.
  • the powder coatings can, if necessary Auxiliaries and additives included. Examples include leveling agents, Flow aids and degassing agents, such as benzoin.
  • the preparation of the powder coatings is carried out by known methods (see. e.g. Product information of the company BASF Lacke + Wegner AG. "Powder coatings", 1990) by homogenizing and dispersing. For example, by means of an extruder, screw kneader, etc., After Production of the powder coatings, these are by grinding and possibly by sifting and sieving to the desired particle size distribution set.
  • Powder coatings based on carboxyl-containing polyester and low molecular weight, crosslinking agent containing epoxide groups are in large number known and described for example in EP-A-389 926, EP-A-371 522, EP-A-326 230, EP-B-110 450, EP-A-110 451, EP-B-107 888. US 4,340,698, EP-B-119 164, WO 87/02043 and EP-B-10 805.
  • polyesters have an acid number in the range of 10-150 mg KOH / g, preferably in the range of 30-100 mg KOH / g.
  • the hydroxyl number of Polyester resins should be ⁇ 30 mg KOH / g.
  • the Polyesters are prepared by the usual methods (see, e.g., Houben Weyl, Methods of Organic Chemistry, 4th Edition, Vol. 14/2, Georg Thieme Verlag, Stuttgart 1961).
  • carboxylic acid component for the preparation of the polyester aliphatic, cycloaliphatic and aromatic di- and Polycarboxylic acids e.g. Phthalic acid, terephthalic acid, Isophthalic acid, trimellitic acid, pyromellitic acid, adipic acid, Succinic acid, glutaric acid, pimelic acid, suberic acid, Cyclohexanedicarboxylic acid, azelaic acid, sebacic acid, etc.
  • These Acids can also be in the form of their esterifiable derivatives (e.g., anhydrides) or their transesterifiable derivatives (e.g. Dimethyl ester) can be used.
  • the alcohol component for the preparation of the carboxyl groups containing polyester A are the commonly used di- and / or Suitable polyols, e.g. Ethylene glycol, 1,2-propanediol and 1,3-propanediol, butanediols, diethylene glycol, triethylene glycol, Tetraethylene glycol, 1,6-hexanediol, neopentyl glycol, 1,4-dimethylolcyclohexane, Glycerol, trimethylolethane, trimethylolpropane, Pentaerythritol, ditrimethylolpropane, dipentaerythritol, diglycerin and the like.
  • Ethylene glycol 1,2-propanediol and 1,3-propanediol
  • butanediols diethylene glycol
  • Tetraethylene glycol 1,6-hexanediol
  • polyesters thus obtained can be used individually or as a mixture different polyesters are used.
  • the as component A) suitable polyesters generally have a Glass transition temperature above 30 ° C.
  • polyesters examples include those under the following products: Crylcoat 314, 340, 344, 2680, 316, 2625, 320, 342 and 2532 from UCB, Drogenbos, Belgium: Grilesta 7205, 7215, 72-06, 72-08, 72-13, 72-14, 73-72. 73-93 and 7401 of Ems-Chemie; Neocrest P670, P671, P672, P678. P662 from ICI and Uralac P2400. Uralac P3400 and Uralac P5000 of the company DSM.
  • the acidic polyester component A also unsaturated, Carboxyl-containing polyester resins in question. These will obtained by polycondensation, for example of maleic acid, Fumaric acid or other aliphatic or cycloaliphatic Dicarboxylic acids with an ethylenically unsaturated double bond, if appropriate together with saturated polycarboxylic acids, as Polycarboxylic.
  • the unsaturated groups can also by the alcohol component, e.g. by Trimethylolpropane monoallyl ether, are introduced into the polyester.
  • the powder coatings contain as component B) 0.8-20.1% by weight. low molecular weight, epoxy group-containing curing agent.
  • epoxy groups containing curing agent is triglycidyl isocyanurate (TGIC).
  • TGIC is in Trade, for example, under the name Araldit PT 810 (manufacturer: Ciba Geigy) available.
  • Other suitable low molecular weight Curing agents containing epoxide groups are 1,2,4-triglycidyltriazoline-3,5-dione, Diglycidyl phthalate and the diglycidyl ester of Hexahydrophthalic.
  • Epoxy-containing polyacrylate resins (component C) polymers are understood by copolymerization of at least one ethylenically unsaturated monomer containing at least contains an epoxide group in the molecule, with at least one other ethylenically unsaturated monomer containing no epoxide group, wherein at least one of the monomers is an ester of Acrylic acid or methacrylic acid.
  • Epoxide group-containing polyacrylate resins are known (see, for example, EP-A-299 420, DE-B-22 14 650, US-A-4,091,048 and US-A-3,781,379).
  • ethylenically unsaturated monomers containing at least one Epoxide group contained in the molecule are glycidyl acrylate, Called glycidyl methacrylate and allyl glycidyl ether.
  • alkyl esters of acrylic and Methacrylic acid containing 1 to 20 carbon atoms in the alkyl radical in particular methyl acrylate, methyl methacrylate, ethyl acrylate, Ethyl methacrylate, n-butyl acrylate, iso-butyl acrylate, t-butyl acrylate and the corresponding methacrylates, 2-ethylhexyl acrylate and 2-ethylhexyl methacrylate called.
  • ethylenic unsaturated monomers containing no epoxide groups in the molecule are acids, e.g.
  • Acrylic acid and methacrylic acid acid amides, such as e.g. Acrylic acid and methacrylamide, vinylaromatic Compounds such as styrene, methylstyrene and vinyltoluene, nitriles, such as Acrylonitrile and methacrylonitrile, vinyl and vinylidene halides, such as Vinyl chloride and vinylidene fluoride, vinyl esters, e.g. Vinyl acetate and Vinyl propionate, and hydroxyl group-containing monomers, such as e.g. Hydroxyethyl acrylate and hydroxyethyl methacrylate.
  • vinylaromatic Compounds such as styrene, methylstyrene and vinyltoluene
  • nitriles such as Acrylonitrile and methacrylonitrile
  • vinyl and vinylidene halides such as Vinyl chloride and vinylidene fluoride
  • vinyl esters e.g. Vinyl acetate and Vinyl
  • the epoxy group-containing polyacrylate resin (component C) has an epoxide equivalent weight of 350 to 2,000.
  • the polyacrylate resins containing epoxide groups have a number average molecular weight (determined by gel permeation chromatography using a polystyrene standard) of 1000 to 15000 and a glass transition temperature (T G ) of 30-80 (measured by Differential Scanning Calorimetry (DSC).
  • the epoxy group-containing acrylate resin may be generally good known methods prepared by free-radical polymerization become. Commercially, such epoxide groups are included Polyacrylate resins, for example, available under the name Almatex PD 7610 and Almatex PD 7690 (manufacturer: Mitsui Toatsu).
  • the powder coatings according to the invention contain Component D) 0.5-13.6 wt .-% low molecular weight di- and / or Polycarboxylic acids and / or di- and / or polyanhydrides.
  • Prefers are as component D) saturated, aliphatic and / or cycloaliphatic dicarboxylic acids, e.g. glutaric, Adipic acid, pimelic acid, suberic acid, azelaic acid, Cyclohexanedicarboxylic acid, sebacic acid, malonic acid, dodecanedioic acid and succinic acid.
  • component D) as well aromatic di- and polycarboxylic acids, e.g.
  • phthalic acid Terephthalic acid, isophthalic acid, trimellitic acid and pyromellitic acid, of course also in the form of their anhydrides, as far as they exist.
  • the amounts of the powder coating components A) to D) become such chosen that the ratio of the epoxide groups from B) and C) to the Sum of the carboxyl and anhydride groups from A) and D) 0.75-1.25: 1 is. This ratio is preferably 0, 9-1, 1: 1.
  • the powder coatings contain 50 to 90%, preferably 60 to 80 wt .-% Binder and 10 to 50 wt .-%, preferably 20 to 40 wt .-% fillers.
  • Suitable fillers are glycidyl-functionalized crystalline Silicic acid modifications into consideration. Usually they are in the said range of 10 to 50 wt .-%, based on the Total weight of the powder coating used. In some cases, however also filler contents of more than 50 wt .-% possible.
  • Crystalline silica modifications include quartz, cristobalite, tridymite, keatite, stishovite, melanophlogite, coesite and fibrous silica.
  • the crystalline silica modifications are glycidyl functionalized, with glycidyl group functionalization achieved by surface treatment. These are, for example, quartz, cristobalite and fused silica based silica modifications prepared by treating the crystalline silica modifications with epoxysilanes.
  • the glycidyl-functionalized silicic acid modifications are available on the market for example under the name Silbond R 600 EST and Silbond R 6000 EST (manufacturer: Quarzwerke GmbH) and are prepared by reacting crystalline silica modifications with epoxy silanes.
  • the powder coatings contain 10 to 40 wt .-%, based on the total weight of the powder coating, on glycidylgrppenfunktionalinstrumenten crystalline silicic acid modifications.
  • the powder coatings may contain other inorganic fillers, For example, titanium oxide, barium sulfate and silicate-based fillers such as e.g. Talc, kaolin, magnesium, aluminum silicates, mica and contain similar.
  • the powder coatings can, if necessary Auxiliaries and additives included. Examples include leveling agents, Flow aids and degassing agents, such as benzoin.
  • the preparation of the powder coatings is carried out by known methods (see. e.g. Product information of BASF Lacke + Wegner AG, "Powder coatings", 1990) by homogenizing and dispersing, For example, by means of an extruder, screw kneader, etc. After Production of the powder coatings, these are by grinding and possibly by sifting and sieving to the desired particle size distribution set.
  • step A a one or more steps on a metallic substrate as Base layer applied (step A), which then preferably is dried (step B). On this base coat is then coated by electrocoating (step C). Then it is rinsed (step D). The entire coating will finally dried in a final drying process (step E).
  • the coating thus produced is characterized in that even with a small layer thickness and specific weight the lacquer layer has a surprisingly low porosity.
  • the porosity can be determined by the can to be tested filled with an electrolyte and by applying a fixed Test voltage is determined, whether the insulating effect of the film over a Period of 4 seconds is sufficient. In detail should be at a Voltage of 6.3 volts in a 1 wt .-% NaCl solution for the Amperage a limit of not more than 1.0 mA can be achieved.
  • the coating produced by the process according to the invention preferably has a specific weight of the paint layer of 1 to 10 g / m 2 , particularly preferably 2 to 5 g / m 2 .
  • the electrophoretically applied layer of the electrodeposition coating has a weight fraction of less than 10%, preferably less than 5%, of the total weight of the coating layer of the laminate.
  • the electrodeposition paint is preferred by the anodic Electrocoating applied (step C).
  • the anodic Electrocoating takes place in an open immersion bath constantly is stirred and pumped to settle the dispersed Resin particles and pigments to avoid.
  • the coating is carried out with direct current in the range of 20 to 500 volts, wherein the metal container to be coated is connected as an anode.
  • the coating time is between o, 1 sec and 3 minutes.
  • the method according to the invention is the electrophoretic coating according to step C, preferably for a duration of 0.1 to 180 seconds, completely more preferably carried out from 10 to 30 seconds.
  • the case applied voltage is 10 to 400 V, preferably 50 to 150 V.
  • step D After rinsing (step D) with water and optionally ultrafiltrate is the Wet film at temperatures of 150 ° C to 250 ° C with a burn-in time hardened from 1 second to 30 minutes.
  • beverage and food cans are short at high Temperatures burned in (1 second to 250 seconds at Temperatures from 200 to 230 ° C). After burning is the Layer thickness of the can interior coating generally in the range of 3 ⁇ m to 15 ⁇ m, preferably in the range of 4 ⁇ m to 8 ⁇ m.
  • the metal container to be coated can from the consist of different materials and the most diverse Have geometries.
  • the materials used are especially aluminum, Black plate, tinplate and various iron alloys in question, possibly with a passivation layer based on nickel, chromium and Zinc compounds are provided.
  • the packaging can take the form of Canned parts, ie hulls and lids, as 3-piece cans and as 2-piece. stretched-deep-drawn or otherwise deep-drawn Beverage and food cans are coated.
  • the Metal containers coated according to the invention are preferably on or multi-level aluminum and / or steel in its basic substance manufactured.
  • the paint coating produced by the process according to the invention is preferably located only in the interior of the metal container. However, it is also included that a paint layer - possibly different composition - inside and outside of the metal container.
  • a paint weight gain / can by the refinish was not measurable.
  • the mechanical properties of the refinished and repeatedly dried cans do not change.
  • the porosity decreased from 1.2 to 0.1 mA at best by the ETL with a grade improvement in the CuSO 4 test from 2.1 to 0.1.
  • ET-coated, not-dried cans were immediately returned with and without voltage through the pilot plant.
  • Wet on wet ETL averages of 6 doses, with and without voltage (doses: L2DH20A) Standard pilot plant Standard spray system Subsequently 0V ETL at 86V Lackgew / box 300mg 360mg 300mg 300mg Porosity 475 4V. 30 sec. 2.1mA 1.3mA 7,0mA 1.6mA Grading CuSO 4 24h (0-5) 2.1 1.3 2.4 1.7
  • a typical paint weight / can for beer and beverages is 360 mg for the spray technology and with the electrocoating 300 mg.
  • the powder coating A was baked at 200 ° C for 5 min.
  • the mechanical properties of the dried paint films are generally not changed, a measurable paint weight gain / box does not take place.
  • Electrocoating non-dried (wet film) cans reduced the porosity to a lesser extent.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Paints Or Removers (AREA)
  • Application Of Or Painting With Fluid Materials (AREA)
  • Solid-Sorbent Or Filter-Aiding Compositions (AREA)
EP97940152A 1996-09-02 1997-09-02 Porenfreie beschichtung von metallbehältern Expired - Lifetime EP0925389B1 (de)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE19635560A DE19635560A1 (de) 1996-09-02 1996-09-02 Porenfreie Beschichtung von Metallbehältern
DE19635560 1996-09-02
PCT/EP1997/004764 WO1998010124A1 (de) 1996-09-02 1997-09-02 Porenfreie beschichtung von metallbehältern

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EP0925389B1 true EP0925389B1 (de) 2001-05-30

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AT (1) ATE201726T1 (es)
BR (1) BR9711650A (es)
CA (1) CA2263092A1 (es)
DE (2) DE19635560A1 (es)
ES (1) ES2159147T3 (es)
WO (1) WO1998010124A1 (es)

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GB1118672A (en) * 1963-10-04 1968-07-03 Porter Paints Ltd Electrophoretic painting process
US3616394A (en) * 1969-03-03 1971-10-26 Continental Can Co Electrophoretic repair coating of enamel coated substrates
US4007102A (en) * 1974-01-09 1977-02-08 Kaiser Aluminum & Chemical Corporation Electrocoating aluminum sheet or strip
ATE48660T1 (de) * 1984-06-18 1989-12-15 Alusuisse Verfahren zum beschichten von schnittkanten.
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DE19635560A1 (de) 1998-03-05
ES2159147T3 (es) 2001-09-16
BR9711650A (pt) 1999-08-24
EP0925389A1 (de) 1999-06-30

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