Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
  • C09D5/44—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes for electrophoretic applications
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
  • C09D5/44—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes for electrophoretic applications
  • C09D5/4488—Cathodic paints
  • C09D5/4492—Cathodic paints containing special additives, e.g. grinding agents
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
  • C09D5/44—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes for electrophoretic applications
  • C09D5/4419—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes for electrophoretic applications with polymers obtained otherwise than by polymerisation reactions only involving carbon-to-carbon unsaturated bonds
  • C09D5/443—Polyepoxides
  • C09D5/4457—Polyepoxides containing special additives, e.g. pigments, polymeric particles

Definitions

• the invention relates to aqueous electrodeposition lacquer baths containing cathodically depositable synthetic resins.
• Cationic electrodeposition coating is a coating process that is frequently used primarily for priming, especially in the field of automotive primers, in which water-thinnable synthetic resins carrying cationic groups are applied to electrically conductive bodies with the aid of direct current.
• Electrocoating baths of the type described above are e.g. disclosed in the following patent documents:
• Lacquer systems of this type can be used to achieve excellent • quality paintwork.
• surface defects in particular craters
• the causes of these surface defects can lie in the nature of the components used for the electrocoat materials (so-called system-inherent causes).
• contaminants carried into the electroplating bath are the cause of the occurrence of the above-mentioned surface defects. Examples of such contaminations are deep-drawing greases, anti-corrosion greases, seam sealing materials, lubricating greases, etc.
• these impurities are also introduced into the film.
• the lacquer film is stoved in, it can then occur due to incompatibilities between the lacquer binder and the contamination. come to the above surface defects.
• J 6 1115 974 describes a reaction product of a polyepoxy resin modified with dimeric fatty acids with polyoxyalkylene polyamine. This product is intended to suppress the tendency of KTL materials to crater.
• EP-A 70 550 describes a reaction product of a polyepoxy resin with a polyoxyalkylene polyamine with primary amino groups. This material is also intended to improve the electrically deposited lacquer films by eliminating or at least minimizing the tendency to crater. But these products also lead to sustained interim liability problems for fillers and top coats.
• the advantages achieved by the invention are to be seen essentially in the fact that the electro-dip lacquer baths according to the invention provide lacquer films which show no or only a few surface defects, without adhesion problems occurring with over-lacquered lacquer layers.
• the electrocoating baths according to the invention surprisingly show excellent contamination resistance, i.e. the good surface properties of the baked films are retained even if substances causing surface defects are introduced into the electrocoating baths according to the invention.
• the electrodeposition lacquer baths according to the invention can in principle contain all cathodically separable external or self-crosslinking synthetic resins suitable for the production of electrodeposition lacquer baths.
• the electrocoating baths which contain cationic, amine-modified epoxy resins as cathodically depositable synthetic resins are preferred. Both self- and externally cross-linking cationic amine-modified epoxy resins are known. External crosslinking cationic amine-modified epoxy resins are preferably used.
• Cationic reaction products are formed from cationic amine-modified epoxy resins
• (C) understood polyols, polycarboxylic acids, polyamines or polysulfides.
• Polyepoxides are understood to mean compounds which contain two or more epoxy groups in the molecule.
• All compounds which contain two or more epoxy groups in the molecule are suitable as component (A) for producing the cationic amine-modified epoxy resins.
• Preferred compounds are those which contain two epoxy groups in the molecule and have a relatively low molecular weight of at most 750, preferably 400 to 500.
• Particularly preferred (A) components are compounds which can be prepared by reacting
• component (b) a compound which reacts monofunctionally to epoxy groups under the given reaction conditions and contains a phenol or thiol group or a mixture of such compounds, components (a) and (b) in a molar ratio of from 10: 1 to 1: 1, preferably 4: 1 to 1.5: 1, and the reaction of component (a) with component (b) is carried out at 100 to 190 ° C., optionally in the presence of a catalyst (cf. DE-OS-35 18 770)
• a components are compounds which can be produced by a starter which reacts at 100 to 195 ° C., optionally in the presence of a catalyst, by a monofunctional reactant which either has an alcoholic OH group or a phenolic OH Group or an SH group, initiated polyaddition of a diepoxide compound and / or a mixture of diepoxide compounds, optionally together with at least one monoepoxide compound, to form an epoxy resin in which the diepoxide compound and starter in a molar ratio of greater than 2: 1 to 10: 1 are installed (see DE-0S-35 18 732).
• Polyepoxides which can be used for the production of the particularly preferred (A) components and also themselves as (A) components are polyglycidyl ethers of polyphenols prepared from polyphenols and epihalohydrins.
• polyphenols such. B. very particularly preferably bisphenol A and bisphenol F can be used.
• ethylene glycol diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,4-propylene glycol, 1,5-pentanediol, 1,2,6-hexanetriol, glycerol and bis- (4-hydroxycyclohexyl-) 2, 2-propane.
• polyglycidyl esters of polycarboxylic acids such as.
• oxalic acid succinic acid, glutaric acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, dimerized linoleic acid
• Typical examples are glycidyl adipate and glycidyl phthalate.
• hydantoin epoxides epoxidized polybutadiene and polyepoxide compounds which are obtained by epoxidizing an olefinically unsaturated aliphatic compound.
• Modified polyepoxides are understood to be polyepoxides in which some of the reactive groups have been reacted with a modifying compound.
• carboxyl groups such as saturated or unsaturated monocarboxylic acids (e.g. benzoic acid, linseed oil fatty acid, 2-ethylhexanoic acid, versatic acid), aliphatic, cycloaliphatic and / or aromatic dicarboxylic acids of various chain lengths (e.g. adipic acid, sebacic acid, Isophthalic acid or dimeric fatty acids), Hydroxykylcarboxylic acids (eg lactic acid, dirnethylolpropionic acid) and polyesters containing carboxyl groups or
• saturated or unsaturated monocarboxylic acids e.g. benzoic acid, linseed oil fatty acid, 2-ethylhexanoic acid, versatic acid
• aliphatic, cycloaliphatic and / or aromatic dicarboxylic acids of various chain lengths e.g. adipic acid, sebacic acid, Isophthalic acid or dimeric fatty acids
• N N'-dialkylalkylenediamines such as dimethylethylenediamine, N, N ! -Dialkyl-polyoxyalkylene amines such as N, N-dimethyl-polyoxypropylene diamine, cyanoalkylated alkylene diamines such as bis-NjN'cyanethyl-ethylenediamine, cyanoalkylated poly- oxialkylene amines such as bis-N, N'-cyanoethyl polyoxypropylene diamine, polyaminoamides such as, for. B.
• Versamides especially terminal amino-containing reaction products from diamines (z. B. Hexymethylenediamine), polycarboxylic acids, especially dimer fatty acids and monocarboxylic acids, especially fatty acids, or the reaction product of one mole of diaminohexane with two moles of monoglycidyl ether or monoglycidyl ester, especially glydidyl ester o -ver ⁇ branched fatty acids such as versatic acid, or
• Hydroxyl group-containing compounds such as neopentyl glycol, bis-ethoxylated neopentyl glycol. Hydroxipivalic acid - neopentylglycol ester, dimethylhydantoin-N, N'-diethanol, 1,6-hexanediol, 2,5-hexanediol, 1,4-bis (hydroximethyl) cyclohexane, 1,1-isopropylidene-bis- (p-phenoxy) -2-propanol, trimethylolpropane, pentaerythritol or amino alcohols such as
• Triethanolamine methyldiethanolamine or hydroxyl group-containing alkyl ketimines such as aminomethylpropanediol-1,3-methyl-isobutyl ketimine or tris (hydroximethyl) aminomethane-cyclohexanone kimine as well as polyglycol ethers, polyester polyols, polyether polyols, polycaprolactone polyols or different functionality and polycaprolactoly polyols
• the amine should preferably be a water-soluble compound.
• examples of such amines are mono- and dialkylamines, such as methylamine, ethylamine, propylamine, butylamine, dimethylamine, diethylamine, dipropylamine, methylbutylamine and the like.
• the like are also suitable alkanolamines, e.g. Methylethanolamine, diethanolamine u.
• Dialkylaminoalkyl-aeine e.g. Dimethylaminoethylamine, diethylaminopropylamine, dimethylaminopropylamine and the like.
• Suitable In most cases, low molecular weight amines are used, but it is also possible to use higher molecular weight monoamines.
• Polyamines with primary and secondary amino groups can be reacted with the epoxy groups in the form of their ketimines.
• the ketimines are produced from the polyamines in a known manner.
• the amines can also contain other groups, but these should not interfere with the reaction of the amine with the epoxy group and should not lead to gelation of the reaction mixture.
• the charges required for water dilutability and electrical separation can be generated by protonization with water-soluble acids (e.g. boric acid, formic acid, lactic acid, preferably acetic acid) or by reacting the oxirane groups with salts of an amine.
• water-soluble acids e.g. boric acid, formic acid, lactic acid, preferably acetic acid
• the salt of a tertiary amine can be used as the salt of an amine.
• the amine portion of the amine acid salt is an amine which can be unsubstituted or substituted as in the case of the hydroxylamine, these substituents should not interfere with the reaction of the amine acid salt with the polyepoxide and the reaction mixture should not gel.
• Preferred amines are tertiary amines such as dimethylethanolamine, triethylamine, trimethylamine, triisopropylamine and the like. The like. Examples of other suitable amines are given in US Pat. No. 3,839,252 in column 5, line 3 to column 7, line 42.
• polyols As component (C), polyols, polycarboxylic acids, polyamines or polysulfides or mixtures of compounds from these classes of substances are used.
• the polyols in question include diols, triols and higher polymeric polyols, such as polyester polyols, polyether polyols.
• Polyalkylene ether polyols suitable for component (C) correspond to the general formula
• examples are poly (oxytetramethylene) glycols and poly (oxyethylene) glycols.
• polyether polyols obtained by reacting a cyclic polyol, e.g. Bisphenol A, with ethylene oxide or a mixture of ethylene oxide with an alkylene oxide which contains 3 to 8 carbon atoms, are available as component (C), then particularly preferred cationic, amine-modified epoxy resins are obtained (cf. EP- A-74634).
• Polyester polyols can also be used as polymeric polyol components. You can the polyester polyols by polyesterification of organic polycarboxylic acids or their anhydrides with organic polyols, the primary Contain hydroxyl groups, produce.
• the polycarboxylic acids and the polyols are usually aliphatic or aromatic dicarboxylic acids and diols.
• the diols used to prepare the polyesters include alkylene glycols, such as ethylene glycol, butylene glycol, neophenyl glycol and other glycols, such as cyclohexanedimethanol.
• the acid component of the polyester consists primarily of low molecular weight carboxylic acids or their anhydrides with 2 to 18 carbon atoms in the molecule.
• Suitable acids are, for example, phthalic acid, isophthalic acid, terephthalic acid, tetrahydrophthalic acid, hexahydrophthalic acid, adipic acid, azelaic acid, sebacic acid, maleic acid and glutaric acid.
• phthalic acid isophthalic acid, terephthalic acid, tetrahydrophthalic acid, hexahydrophthalic acid, adipic acid, azelaic acid, sebacic acid, maleic acid and glutaric acid.
• their anhydrides if they exist, can also be used.
• Polyester polyols derived from lactones can also be used as component (C). These products are obtained by reacting a £ -caprolactone with a polyol. Such products are described in U.S. Patent 3,169,945.
• polylactone polyols which are obtained by this reaction are distinguished by the presence of a terminal hydroxyl group and by recurring polyester fractions which are derived from the lactone. These recurring
• n at least 4, preferably 4 to 6, and the substituent is hydrogen, an alkyl radical
• Aliphatic and / or alicyclic polyfunctional alcohols or carboxylic acids with a molecular weight below 350 are also used as component (C). These advantageously have a branched aliphatic chain, in particular with at least one neostructure.
• Suitable compounds correspond to the following general ones
• R 3 H, alkyl radical with 1 to 5 carbon atoms
• Examples include: diols, such as ethylene glycol, diglycol, dipropylene glycol, dibutylene glycol, triglycol, 1,2-propanediol, 1,3-propanediol, 2,2-dimethyl-l, 3-propanediol, 2,2-diethyl-l, 3-propanediol, 2-methyl-2-ethyl-l, 3-propanediol, 2-methyl-2-propyl-l, 3-propanediol, 2-ethyl-2-butyl-l, 3-propanediol, 1, 2-butanediol, 1,4-butanediol, 2,3-butanediol, 2-ethyl-1,4-butanediol, 2,2-diethyl-l, 3-butanediol, butene-2-diol-l, 4, 1, 2-pentanediol, 1,5-pentaned
• Some preferred diols are 2,2-dimethyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2,2-dimethyl-3-hydroxy- propyl 2,2-dimethyl hydroxypropionate and 4,4'-isopropylidene biscyclohexanol.
• dicarboxylic acids are suitable as carboxylic acids, such as oxalic acid, malonic acid, 2,2-dimethylmalonic acid, succinic acid, glutaric acid, adipic acid, hexahydrophthalic acid, maleic acid, fumaric acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, itaconic acid, citraconic acid - acid and mesaconic acid.
• Preferred dicarboxylic acids are e.g. 2,2-dimethylmalonic acid and hexahydrophthalic acid.
• Long-chain dicarboxylic acids can also be used as component (C).
• Examples include dimeric acid such as dimeric linoleic acid.
• Polyamines suitable as component (C) can be e.g. by reacting primary diamines and monoepoxides.
• the secondary substituted diamines formed modify the epoxy resins in a suitable manner.
• Primary tertiary diamines or alkanolamines such as aminoethanol or aminopropanol can also be used as component (C).
• Possible polyfunctional SH compounds are reaction products of organic dihalides with sodium polysulfide.
• Other SH connections are e.g. Reaction products of hydroxyl-containing linear polyesters, polyethers or polyurethanes with mercaptocarboxylic acids such as mercaptoacetic acid, 2-mercaptopropionic acid, 3-mercapto-propionic acid, mercaptobutyric acid and the like.
• Very particularly preferred electrocoating baths are obtained if, as cationic, amine-modified epoxy resins, reaction products of (A) polyepoxides, (B) primary and / or secondary amines or their salts and / or salts of tertiary amines and (C) polyols, in particular polyester and / or polyether polyols.
• the cationic amine-modified epoxy resins can be used both as externally crosslinking synthetic resins and as self-crosslinking synthetic resins.
• Self-crosslinking cationic amine-modified epoxy resins can be obtained, for example, by chemical modification of the cationic amine-modified epoxy resins.
• a self-networking system can e.g. are obtained by reacting the cationic amine-modified epoxy resin with a partially blocked polyisocyanate, which on average has one free isocyanate group per molecule and whose blocked isocyanate groups are only unblocked at elevated temperatures.
• Preferred electrocoating baths are obtained if externally crosslinking cationic amine-modified epoxy resins are used as the cathodically depositable synthetic resins in combination with a suitable crosslinking agent.
• crosslinking agents examples include phenoplasts, polyfunctional Mannich bases, melamine resins, benzoguanamine resins, blocked polyisocyanates and compounds which contain at least two groups of the general formula R 1 -0-C0-.
• the remainder R means:
• R 1 R 2 -0-C0-CH 2 -, R 3 -CH0H-CH 2 -, R 4 -CH0R 5 -CH0H-CH 2 -
• R 2 alkyl
• R 3 H, alkyl, R 6 -0-CH 2 - or R 6 -C0-0-CH 2 ⁇
• R 4 H or alkyl
• R 5 H, alkyl or aryl
• R alkyl, cycloalkyl or aryl
• Preferred electrocoating baths are obtained if blocked polyisocyanates and / or compounds which contain at least two groups of the general formula R -0-C0- are used as crosslinking agents.
• Any polyisocyanates in which the isocyanate groups have been reacted with a compound can be used as blocked polyisocyanates, so that the blocked polyisocyanate formed is resistant to hydroxyl and amino groups at room temperature, at elevated temperatures, generally in the range from about 90 C to about 300 ° C, but reacts.
• Any organic polyisocyanates suitable for crosslinking can be used in the preparation of the blocked polyisocyanates.
• the isocyanates which contain about 3 to 36, in particular about 8 to about 15, carbon atoms are preferred.
• diisocyanates examples include hexamethylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate and 1-isocyanatomethyl-5-isocyanato-1,3,3-trimethylcyclohexane.
• Polyisocyanates with higher isocyanate functionality can also be used. Examples of this are trimerized hexamethylene diisocyanate and trimerized isophorone diisocyanate. Mixtures of polyisocyanates can also be used.
• the organic polyisocyanates which are suitable as crosslinking agents in the invention can also be prepolymers which are derived, for example, from a polyol including a polyether polyol or a polyester polyol.
• Any suitable aliphatic, cycloaliphatic or aromatic alkyl mono alcohols can be used to block the polyisocyanates.
• suitable aliphatic alcohols such as methyl, ethyl, chloroethyl, propyl, butyl, amyl, hexyl, heptyl, octyl, nonyl, 3,3,5-trimethylhexyl, decyl and lauryl alcohol ; cycloaliphatic alcohols such as cyclopentanol and cyclohexanol; aromatic alkyl alcohols, such as phenylcarbinol and methylphenylcarbinol.
• blocking agents are hydroxylamines such as ethanolamine, oximes such as methyl ethyl ketone oxime, acetone oxime and cyclohexanone oxime or amines such as dibutylamine and diisopropylamine.
• oximes such as methyl ethyl ketone oxime, acetone oxime and cyclohexanone oxime
• amines such as dibutylamine and diisopropylamine.
• the polyisocyanates and blocking agents mentioned can also be used, in suitable proportions, for the preparation of the partially blocked polyisocyanates mentioned above.
• the crosslinking agent is generally used in an amount of 5 to 60% by weight, preferably 20 to 40% by weight, based on the cationic amine-modified epoxy resin.
• Such homopolymers or copolymers are prepared by polymerizing an alkyl vinyl ether, optionally together with other copolymerizable monomers. The polymerization takes place according to well-known methods, preferably cationically.
• an alkyl vinyl ether of the general formula CH 2 CH-0-R, where R is an alkyl radical having 2 to C atoms, preferably an ethyl radical, if appropriate together with - Up to 20 wt .-% of a copolymerizable monomer or a copolymerizable monomer mixture.
• the average molecular weight (weight average) of the polymers obtained should be in the range from 5 * 10 2 to 1 * 105 g / mol, preferably in the range from 1-10 to 5 * 10 g / mol.
• the above average molecular weight can e.g. B. gel permeation chromatography z. B. can be determined under the following conditions:
• RI reffraction index
• Knauer differential refractometer stage 8
• Calibration 10 polystyrene standards with a known molar mass of approx. 600 to 400,000, creation of the calibration line using linear regression.
• Alkyl vinyl ether monomers used with preference are ethyl and (iso) propyl vinyl ether, ethyl vinyl ether is particularly preferably used.
• Electrodeposition paint baths which contain homopolymers of ethyl vinyl ether are very particularly preferred.
• Examples of monomers which can be copolymerized with alkyl vinyl ethers are styrene and alkyl (meth) acrylates, such as, for example, ethyl (eth) acrylate and methyl (eth) acrylate.
• the electro dip lacquer baths according to the invention are produced by generally well-known methods.
• the synthesis of the cathodically depositable synthetic resins takes place according to well known methods (cf. for example DE-PS-27 01 002 and the further patent documents cited on page 1) in organic solvents.
• the synthetic resin solutions or dispersions obtained in this way are converted into an aqueous phase in neutralized form.
• Pigments are preferably incorporated in the form of a pigment paste into the aqueous dispersion of the cathodically depositable resins.
• pigment pastes e.g. epoxy-amine adducts containing quaternary ammonium groups are used.
• the pigment pastes can contain all pigments suitable for electrocoating.
• titanium dioxide is the only or the main white pigment.
• other white pigments or extenders such as antimony oxide, zinc oxide, basic lead carbonate, basic lead sulfate, barium carbonate, porcelain, clay, calcium carbonate, aluminum silicate, silicon dioxide, magnesium carbonate and magnesium silicate can also be used.
• cadmium yellow, cadmium red, carbon black, phthalocyanine blue, chrome yellow, toluidyl red and hydrated iron oxide can be used as colored pigments.
• the pigment paste can also contain plasticizers, fillers, wetting agents, etc.
• the pigment paste is added to the aqueous dispersion of the cathodically depositable synthetic resin in such an amount that the finished electrodeposition bath has the properties required for the deposition.
• the weight ratio between pigment and cathodically depositable synthetic resin is 0.05 to 0.5.
• alkyl vinyl ether homo- or copolymers used according to the invention are preferably incorporated into the pigment paste or into the organic resin solution or dispersion. It may be advantageous to dissolve the polymers in question in a suitable solvent (e.g. butanol, ethyl acetate, butyl glycol, methyl isobutyl ketone or white spirit). In some cases it can be useful to use emulsifiers.
• a suitable solvent e.g. butanol, ethyl acetate, butyl glycol, methyl isobutyl ketone or white spirit. In some cases it can be useful to use emulsifiers.
• alkyl vinyl ether homopolymers or copolymers used in accordance with the invention can be incorporated into the electrocoating baths at any time during production and also after the electrocoating baths have been completed.
• the alkyl vinyl ether homo- or copolymers used in accordance with the invention are incorporated into the electrocoating baths in such amounts that the finished electrocoating baths are preferably 10 to 10000 pp, particularly preferably 100 to 1500 ppm, very particularly preferably 150 to 500 ppm, of Alkyl vinyl ether homo- or copolymers contain (the indication ppm - parts per illion - is based on parts by weight). It goes without saying that mixtures of different alkyl vinyl ether homo- or copolymers can also be used.
• the surface disruptive effect of the alkyl vinyl ether homo- or copolymers is particularly surprising because the materials used in the past for this purpose generally have a surface activity which can be derived from their chemical structure. They are often surfactants, e.g. Polyethylene oxide modified silicones or around materials with very low surface tensions of approx. 20 to 25 mN / m. However, the alkyl vinyl ether homo- or copolymers used according to the invention have neither the structure nor the mode of action of surfactants and, at about 32 mN / m, a surface tension value customary for organic materials.
• surfactants e.g. Polyethylene oxide modified silicones or around materials with very low surface tensions of approx. 20 to 25 mN / m.
• the alkyl vinyl ether homo- or copolymers used according to the invention have neither the structure nor the mode of action of surfactants and, at about 32 mN / m, a surface tension value customary for organic materials.
• the electrocoating baths according to the invention can also contain other customary additives, such as, for example, Additional solvents, antioxidants, surface-active agents, etc.
• the solids content of the electrocoating baths according to the invention is preferably 7 to 35 parts by weight, particularly preferably 12 to 25 parts by weight.
• the pH of the electrocoating baths is between 4 and 8, preferably between 5 and 7.5.
• the electrocoating baths according to the invention can be used to coat any electrically conductive substrates, but in particular to coat metals such as steel, aluminum, copper and the like. Like. Use.
• the invention also relates to a method for coating electrically conductive substrates, in which (1) the substrate is immersed in an aqueous electrocoating bath which contains at least one cathodically depositable synthetic resin,
• the electrocoating bath is brought into contact with an electrically conductive anode and with the electrically conductive substrate connected as a cathode.
• electrical current passes between the anode and cathode, a firmly adhering lacquer film is deposited on the cathode.
• the temperature of the electrocoating bath should be between 15 and 35 ° C, preferably between 20 and 30 ° C.
• the applied voltage can vary over a wide range and can e.g. are between two and a thousand volts. Typically, however, voltages between 50 and
• the current density is usually between about 10 and 100 amperes / m. The current density tends to drop in the course of the deposition.
• the coated object is rinsed off and is ready for baking.
• the deposited lacquer films are generally baked at temperatures of 130 to 200 ° C. for a period of 10 to 60 minutes, preferably at 150 to 180 ° C. for a period of 15 to 30 minutes.
• R represents an alkyl radical having 2 to 4 carbon atoms
• Emulsifier mixture based on Geigy Amin C (Geigy Industrial Chemicals) 120 parts, Surfynol 104 (Air Products and Chemicals) 120 parts, butylglycol
• MIBK methyl isobutyl ketone
• Epikote 829, Capa 200 and xylene are placed in a reaction vessel and heated to 210 ° C. under a protective N gas. Water is then removed from the circuit for half an hour. The mixture is then cooled to 150 ° C., bisphenol A and 1.6 parts of dimethylbenzylamine are added. The mixture is then heated to 180 ° C. and kept at this temperature for half an hour. Then it is cooled to 130 ° C. and the remaining amount of dimethylbenzylamine is added. The temperature is then kept for 2 1/2 hours, then the isocyanate crosslinker, the diketimine and N-methylethanolamine are added and the temperature is then kept at 110 ° C. for half an hour. The hexylglycol is then added. The reaction mixture is then dispersed in the deionized water, which contains glacial acetic acid and emulsifier mixture. A vacuum is then applied in order to remove the volatile organic solvents. A solids content of 36% is set.
• the low-boiling solvents are then removed in vacuo and a solids content of 35% is established.
• 500 parts by weight of the ⁇ dispersions according to items 1.1 and 1.2 are mixed with 196 parts of the pigment paste according to item 2 and adjusted to a bath solids content of 20% by weight with deionized water.
• the coating films are deposited on zinc-phosphated sheet at 300 V for 2 minutes.
• the bath temperature is 27 ° C.
• the films are baked at 180 ° C for 20 minutes
• Electrocoating bath 1 dispersion according to item 1.1 with paste according to item 2.2
• Electrocoating bath 2 dispersion according to item 1.1, with
• Electrocoating bath 3 dispersion according to item 1.2 with
• Electrocoating bath 4 dispersion according to item 1.2 with
• Adhesion 2 0.5 0.5 0.5 0.5 0.5
• the KTL baths were then contaminated with 0.1% ASTM oil.
• the oil was stirred in within a day. After that, deposits from the baths such as. described above.
• Ethyl vinyl ether homopolymers (average molecular weight (weight average) between 10 and 10) are added.
• 500 parts by weight of the dispersions according to items 4.1 and 4.2 are mixed with 196 parts of the pigment paste according to item 5 and adjusted to a bath solids content of 20% by weight with deionized water.
• the coating films are deposited on zinc-phosphated sheet at 300 V for 2 minutes.
• the bath temperature is 27 ° C.
• the films are baked at 180 ° C for 20 minutes.
• Electrocoating bath 5 dispersion according to item 1.1 with paste according to item 5
• Electrocoating bath 6 dispersion according to item 4.1 with paste according to item 5
• Electrocoating bath 7 dispersion according to item 1.2 with paste according to item 5
• Electrocoating bath 8 dispersion according to item 4.2 with paste according to item 5 Separation results
• the KTL baths were then contaminated with 0.1% ASTM oil. The oil was stirred in within a day. The baths were then separated as described above.
• reaction mixture is then allowed to cool to 90 ° C. and 183 g of butyl glycol and 293 g of isobutanol are added for further dilution.
• temperature has dropped to 70 ° C.
• 41 g of N, N-dimethylaminopropylamine are added, this temperature is maintained for 3 hours and the mixture is discharged.
• the resin has a solids content of 70.2% and a base content of 0.97 milliequivalents / gram.
• 1120 g of resin according to item 7.1 and 420 g of crosslinking agent according to item 7.2 are stirred at room temperature. After the mixture is homogeneous (15 min), 2.2 g of a defoamer solution and 18 g of glacial acetic acid are stirred in and 678 g of deionized water are added in 4 portions. The mixture is then diluted in small portions with a further 1154 g of deionized water.
• the resulting aqueous dispersion is freed from low-boiling solvents in a vacuum distillation and then diluted to a solids content of 33% with deionized water.
• Electrocoating bath 1 dispersion according to item 7.3 with paste according to item 8.2
• Electrocoating bath 2 dispersion according to item 7.3 with paste analogous to item 8.2 but without ethyl vinyl ether homopolymer
• the KTL baths were then contaminated with 0.1% ASTM oil. The oil was stirred in within one day. The baths were then separated as described above.

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• 1988
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