DE2432593C3 - Process for applying layers of paint to conductive materials - Google Patents

Description

15th

2. The method according to claim 1, characterized in that that the material based on silica is an alkali silicate, a quaternary ammonium silicate, a colloidal silica, a modified silicate or a mixture of these compounds used

3. The method according to claim 1 and 2, characterized in that the alkali metal silicate lithium silicate with a SiO ₂ / Li ₂ O molar ratio of 3.5 to 20, sodium silicate with a SiC ^ / Na ^ O molar ratio of 1 , 5 to 4.0 or potassium silicate with a SiO2 / K ₂ 0 molar ratio of 1.5 to 4.0 is used.

The invention relates to a method for applying layers of paint to conductive materials, wherein an inorganic paint is applied to the conductive material and then to the paint film applying a conventional electrodeposition coating.

So far, a paint has been used as a coating composition on a large scale, its base material consists mainly of a resin. The wide variety of paints and application methods used by the different applications are known.

Recently, an inorganic paint has been developed which is advantageous to the coated work Properties such as incombustibility, heat resistance, hardness and the like. Can give that with a organic paints are not achievable.

An organic paint has poor heat resistance, while the inorganic paint on the other hand is brittle and has remarkably poor flexibility and impact strength. Accordingly was proposed overlaying the organic paint layer with the inorganic paint layer to both Combine characteristics. However, such a method has not yet been used in practice because when laminating the organic paint and the organic paint layer by the usual method the adhesive strength is insufficient.

It is an object of the invention to provide an improved method for producing a laminated paint system both with excellent properties in terms of durability of the inorganic paint

2 ^r > layer as well as the flexibility of the organic paint layer.

In general, it is considered difficult to apply a coating by electrophoretic deposition onto a layer of paint, those on a conductive material

j »has been formed to raise, however, according to of the invention found that it is possible on an inorganic paint layer that has a thickness of 50 μΐη or more has to apply a coating by electrodeposition and that further by

r> multilayer obtained by this electrophoretic deposition Coating system consisting of inorganic and organic coating layers, excellent adhesive strength which cannot be achieved by conventional spray application, brushing on or the like.

Ί "The following is the coating according to the present Invention compared to the usual coating according to the prior art.

Present invention Übl. Coating according to Machu, electrocoating, 1974, pp. 103-110, 169-169

Components of the
composition

Regulation of the pH value
Control of temperature
Apply

Mechanization of Education
of the coating film

Main component of the
formed film

monobasic or sesquiphosphate of Mg, Ca or Al and optionally a filler
not necessary

not necessary

Coating using various coating methods and subsequent drying the monobasic or sesquiphosphate is formed into a film as it is. No washing with water

amorphous monobasic phosphate monobasic zinc phosphate

necessary for the reaction to take place

necessary for the reaction to take place

Coating by spraying or dipping, then washing with Water and then drying

The monobasic zinc phosphate is converted into tertiary zinc phosphate. The water-soluble materials formed are removed by washing with water

crystalline tertiary zinc phosphate

The invention relates to a method for applying paint layers to conductive materials, which thereby is characterized in that an inorganic paint, the at least one material based on of silica and / or a monobasic phosphate or sesquiphosphate of magnesium, calcium or Contains aluminum, applies to the conductive material to form an inorganic layer of paint and then, on this paint layer, an electrophoretically depositable paint by electrophoresis applies to form an organic paint layer.

As is well known, a paint can be made electrically conductive by electrophoretic deposition onto a Paint film can be applied, however, the electrodeposition is in accordance with the invention it is based on a principle that is completely different from that of the usual electrophoretic deposition method is because the inorganic paint layer generally has no electrical conductivity. Organic paint layers are generally non-conductive, so a coating by electrophoretic Deposition cannot be applied to it. On the other hand is an inorganic paint layer more porous and more hydrophilic than an organic paint layer, so that when it is in a water-soluble, electrophoretically depositable paint is dipped. Water penetrates into the inorganic coating layer and consequently the current through it inorganic paint layer can be passed. This is the basis of the application according to the invention of coating layers by electrophoretic deposition.

When an inorganic paint layer is cured at a relatively low temperature without it melts, it is generally more porous than an organic paint layer, so that even if that The starting material for the inorganic paint layer has anti-corrosion properties, the inorganic The paint layer does not have sufficient corrosion resistance, so that numerous rust spots occur, when tested by the salt spray test. In contrast, according to the invention produced multi-layer paint systems excellent corrosion resistance as a result of the synergistic Effect of the inorganic paint layer and the organic paint layer.

The inorganic paints used for the purposes of the invention contain at least one material based on silica and / or a metal phosphate as the base material. Preferred materials based on silica are, for example, alkali silicates, quaternary ammonium silicate, colloidal silicic acid and modified silicates which are obtained by modifying alkali silicates with a metal ion. All customary alkali silicates can be used as alkali silicates. Representative alkali silicates are lithium silicate with a SiCVLizO molar ratio of 3.5 to 20, sodium silicate with an Si0 ₂ / Na20 molar ratio of 1.5 to 4.0 and potassium silicate with a SiCVKjO molar ratio of 1.5 to 4.0 to name. The quaternary ammonium silicate can be produced, for example, by passing an aqueous solution of an alkali silicate and a water-soluble amine through an ion exchange resin. Colloidal silica is a colloidal silica sol that is stabilized with an acid or an alkali. These silica-based materials can be used alone or in admixture of two or more.

Suitable metal phosphates for the purposes of the invention are monobasic phosphates of divalent or higher valent metals, e.g. B. monobasic magnesium phosphate, monobasic calcium phosphate or monobasic aluminum phosphate, sesquis salts of the aforementioned metal phosphates, which can be used alone or in combination.
The materia! based on silica and that

ίο Metal phosphate can be used alone or in combination Base material can be used. Examples of preferred combinations are mixtures of colloidal Silica with a monobasic metal phosphate should be mentioned.

The above-mentioned inorganic materials or their mixtures become two or more optionally with a common colored pigment or filler pigment (ζ. ß. titanium dioxide, red iron oxide, clay and talc) and then mixed by a usual method using a ball mill or a high-speed stirrer mixed to the desired inorganic coating mass. The inorganic Coating material can optionally be surface-active Compounds, curing accelerators or

2 ^r > organic resins are added. Examples of suitable hardening accelerators are silicofluorides, silicoborates and metal oxides.

As electrophoretically depositable coating materials for the purposes of the invention, the

jo various common products of this type can be used. The electrophoretically depositable Coating materials can generally be electrodeposited into anionic and cationic Coating materials are classified. As resins

r> are suitable for the anionic coating materials for example, reaction products of an aliphatic ester with a «, ^ - unsaturated dicarboxylic acid or its anhydride. The aliphatic esters are derivatives of drying oils, semi-drying oils, Tall oil or the like. Modified aliphatic ester resins, for example, are suitable which contain an unsaturated monomer (e.g. styrene, butadiene, Vinyl toluene and methyl methacrylate) are incorporated, alkyd resins made using drying

4 "· or semi-drying oils have been produced, Esters of epoxy compounds with an aliphatic acid (e.g. linseed oil fatty acid, Chinese tung oil fatty acid, Cottonseed oil fatty acid, dehydrated castor oil fatty acid and tall oil fatty acid) or esters of polyolver

> i 'bonds (e.g. ethylene glycol, 1,2-propylene glycol, 1,4-butanediol, diethylene glycol, neopentyl glycol and trimethylolpropane) or resinous polyols (e.g. Allyl alcohol homopolymers or copolymers of allyl alcohol with an ethylenically unsaturated one

V) monomers, e.g. B. styrene) with an aliphatic acid. The aliphatic ester becomes with a «, /! - unsaturated Dicarboxylic acid or its anhydride (e.g. maleic acid, maleic anhydride, itaconic acid, and itaconic anhydride) implemented to the desired resin.

Other suitable resins can be produced by reacting the reaction product of an aliphatic ester and any of the foregoing «, ^ - unsaturated dicarboxylic acids or their anhydrides with a polyol (e.g. ethylene glycol, diethylene glycol

^ col, 2,2-bis (4-hydroxycyclohexyl) propane or trimethyl propane) or by reacting resin materials having a hydroxyl group or an oxirane ring contain (e.g. allyl alcohol-styrene copolymers with

a molecular weight of 500 to 5000, glycidyl methacrylate or methyl methacrylate-n-butyl acrylate copolymers) with an aliphatic acid (e.g. linseed oil fatty acid, Chinese tung oil fatty acid, Cottonseed oil fatty acid, dehydrated castor oil fatty acid or tall oil fatty acid) and subsequent reaction the remaining hydroxyl group with an unsaturated dicarboxylic acid or its anhydride (e.g. Maleic acid, maleic anhydride,! Taconic acid or itacornic anhydride). Also suitable as resins are mixed resin compositions composed of a copolymer resin of a hydroxyalkyl ester of an unsaturated carboxylic acid (e.g. 2-hydroxyethyline ethacrylate or 2-hydroxy-n-propylaerylate), an unsaturated carboxylic acid (e.g. acrylic acid or methacrylic acid) and a Ethylenically unsaturated monomers (e.g. styrene, vinyl toluene, ethyl acrylate, n-butyl acrylate, methyl methacrylate, n-butyl methacrylate, acrylonitrile and vinyl acetate) and an amine-aldehyde condensation product. Suitable as amine-Alde.hyd condensation products are condensation products of formalin with Melamine, benzoguanamine or urea or their analogues, preferably with an alcohol are etherified. Furthermore, mixed resins can be used, which an alkyd resin with relatively high Contain acid number and an amine-aldehyde condensation product.

To prepare the anionic electrodepositable coating materials from the above These resins are first made water-soluble by removing the contained therein Carboxyl group is neutralized. Inorganic bases are suitable as neutralizing agents for this purpose, z. B. potassium hydroxide and ammonia, and organic bases, e.g. B. amines (e.g. methylamine, ethylamine, Dimethylamine, triethylamine, morpholine, ethanolamine, methylethanolamine and ethylenetriamine), which alone or can be used in Mischurg. After the resin has been neutralized, the resulting Mixture optionally various pigments, dispersants or the like can be added. That the resulting mixture is then diluted with tap water or deionized water, the desired electrodepositable coating material is obtained.

The electrodepositable binders, i.e. H. those for the production of the anionic coating materials Resins used can include a mineral acid (e.g. phosphoric acid or sulfonic acid) as well as the Contain the above-mentioned carboxylic acids.

Resins suitable for the cationic electrodepositable coating materials are also cationic resins which have been made soluble with an acid, e.g. B. reaction products of a Epoxy compound with an amine salt (for example, the reaction products of alcoholamine, lactic acid, boric acid and glycol) as described in Japanese Patent Laid-Open No. 13 432/1972. Suitable are also resins that contain a quaternary amine salt residue (e.g. solutions of a copolymer of Amii.ualhylmethacrylat with an ethylenically unsaturated monomer that with acetic acid is neutralized). These resins can be mixed with a pigment and other various additives, such as they are common for inorganic coating materials, are mixed, with the desired electrophoretically depositable coating materials are obtained.

As substrates according to the method according to the invention, conductive materials such. B. Metals (e.g. Iron, copper, zinc and aluminum) or metals provided with a protective coating, as well as materials that penetrate Application of metals or other conductive materials by plating or deposition or by adding a filler, e.g. B. metal powder or graphite, have been made conductive, coated will.

In the method according to the invention, the above-described inorganic coating material is used on the conductive material to be coated using painting methods such as spraying, brushing, Dipping, electrodeposition, and the like, and drying at room temperature or baking under Formation of the inorganic paint layer applied. The one provided with the inorganic paint layer The workpiece is then immersed in a bath which can be electrodeposited as described above Coating material emhäli. Here is the Workpiece when using an anionic coating material as an anode and when using a cationic coating material connected as the cathode. By creating an S'.rom from 10 to 500 V for 1 second to 10 minutes becomes the organic Paint layer formed.

In the electrophoretic deposition process, the inorganic paint layer should have such water resistance have that it is not damaged during the electrophoretic deposition. That through Electrophoretic deposition coated workpiece is then used as such or preferably after Rinse with dried water.

As mentioned earlier, when applying the usual

i ^r > method for applying the organic paint layer to the inorganic paint layer or the inorganic paint layer to the organic paint layer the adhesive strength between the two paint layers is generally insufficient if

^ "rend the paint system when using the process according to the invention has excellent adhesive strength. When microscopic examination is determine that the electrodeposited organic coating is adherent and snug the uneven surface and the pores of the inorganic paint layer has been applied, wherein there is a sufficient anchoring effect and the desired multilayer paint system is obtained will. In addition, in the usual coating

j »by electrophoretic deposition the thickness of the applied layer at most about 30 μΐη, while in the method according to the invention, application by electrophoretic deposition on the usual inorganic paint layer can be made

r "> can, which makes it possible to have a thick coat of paint to form which has similar or better properties than those obtained by conventional electrophoretic deposition applied layers.

According to the invention, by the combination

w) the inorganic paint layer with the electrophoretically deposited coating layer multilayer paint systems with the following excellent properties.

»■ ι (1) The multi-layer paint system according to Invention has better corrosion resistance than conventional paint films produced by electrophoretic Deposition on steel sheets, which one

chemical treatment with zinc phosphate have been applied because of it both those of the raw material of the inorganic paint, d. H. the material on Silicic acid base and the metal phosphate as well as the excellent rust preventive effect Has adhesive strength of the electrophoretically deposited coating.

(2) The disadvantage of the inorganic paint layer, i.e. H. the brittleness is caused by the electrophoretic deposited coating turned off, creating a multilayer paint system with increased impact strength and flexibility is obtained.

(3) The usual electrophoretic deposition has the disadvantage that in cases where the too Coating substrate consists of a metal, in particular iron, the iron ion in the Electrophoretically deposited coating migrates, whereby the paint layer is discolored. In contrast, when working according to the invention, the amount of immigrated Iron ion extremely low compared to the amount that is used in the usual electrophoretic Deposition on steel sheets that have been chemically treated with zinc phosphate are immigrated. The method according to the invention thus enables pure application white paint layers that are not discolored and excellent corrosion resistance too in the case of white electrophoretically applied coatings.

(4) Since the inorganic paint layer has excellent heat resistance and is incombustible, too when the top organic paint layer (electrodeposited layer) under strong

ίο the effect of heat is destroyed, the subsurface becomes still protected by the lower inorganic paint layer.

(5) A wide variety of more customary ones can be applied to the paint systems according to the invention at will Top coats are applied, whereby products with good appearance are obtained.

(6) The inorganic paints used in the invention and electrophoretically depositable Paints are cold water paints so that the product according to the invention vorr Is advantageous from the standpoint of safety and prevention of environmental pollution.

The invention is further illustrated by the following examples. In these examples the Parts by weight.

Example 1 Inorganic Paint A

Sodium silicate (quality no.3) 70 parts Lithium polysilicate 30 parts Titanium dioxide 30 parts kaolin 106 pieces Formaldehyde condensate of alkyl naphthalene sulfonates as Dispersants 2 parts water 120 parts

The ingredients mentioned are dispersed in a ball mill for 15 hours, the desired inorganic paint is obtained.

Electrophoretically depositable paint B
Anhydrous trimellitic acid 32 parts

Propylene glycol 30 parts

Adipic acid 8 parts

The abovementioned components are reacted at 170.degree. C. in such a way that an acid number of 65 is obtained sets, whereupon 30 parts of aliphatic tall oil acid are added and the mixture reacted further until the acid number is 55. After adding 20 Parts of isobutanol to the reaction mixture, the mixture is neutralized with 12 parts of triethylamine 35 parts of red iron oxide are suspended in the resin thus obtained Dilute parts of water to give the desired electrodepositable paint will.

After adjusting the viscosity of the inorganic paint A by adding water to 0.2 Pa s, it is applied to a degreased and roughened with sandpaper mild steel sheet by dip painting, so that the paint layer formed has a thickness of about 20 μm when dry. The applied layer is dried ^{by baking at 160 ° C. for if minutes.} The coated metal sheet is immersed in the electrophoretically depositable paint B and then coated with it by passing a current of 200 V through the coated metal sheet connected as anode for 2 minutes. There; The coated sheet metal is rinsed with water and the paint layer is ^{cured by being baked at 170 ° C. for 30 minutes.} The multilayer paint system produced in this way has a thickness of about 50 μm and very good adhesion between the two paint layers.

In a comparative experiment (comparative example 1, a with the inorganic paint A coated mild steel sheet coated with a commercially available melamine-alkyd resin varnish that is burned in and by dispersing 50 parts of alkyd resin, 17 parts of melamine resin, 27 parts of titanium dioxide, 5 parts n-butyl alcohol and 20 parts of xylene were made is The adhesive strength between the paint layers of the paint system produced in this way isi bad The second (top) coat of paint shows cracking and can be peeled off.

The properties of the paint system produced according to Example 1 are the same as those of a paint system compared that by applying the electrophoretically depositable paint B and the melamine-alkyd resin varnish has been obtained in a thickness of about 50 μm (Comparative Example 2). The results are listed in Table 1.

Table 1

ίο

test

Test method

Product of Example I.

Product of Comparative Example 2

Folding test
Impact strength

Salt spray test
Salt dip test

Warm water immersion test
Flame resistance test

folded at right angles
(Diameter 10 mm)
DuPont method
(Diameter 12.7 mm)

300 g x 50 cm

500 g x 30 cm

500 h with the salt spray tester
tested with cross-cut in the test specimen

Test specimen with cross-cut
is kept in 3% saline solution for 1 month

Test piece is 1 month in
Water kept at 40 C.

Test specimen is 30 minutes
the flame of a gas burner
exposed

fine cracking, no lifting
the paint layer

no rust on the constricted part

no deterioration in

Adhesion Strength

no rust on the constricted part

no deterioration in

Adhesion Strength

slight tarnishing of the coating layer, no blistering
inorganic paint layer
remains behind

Cracking

Cracking
Cracking

incised part rusted in a width of 5 mm;
deteriorated adhesive strength

incised part is
roasted; deep erosion becomes
established; Blistering,
deteriorated adhesive strength around the incised part. Blistering

The layer of paint disappears completely

Example 2
Inorganic paint C

30% aqueous potassium silicate solution,

SiO ₂ : K ₂ O-Mo ratio 3.5 80 parts

colloidal silica 20 parts

red iron oxide 10 parts

Talc 60 parts

Water 50 parts

The above ingredients are dispersed in the manner described in Example 1, whereupon 5 parts of a Paste may be added, formed by dispersing 40 parts of sodium silicofluoride in 60 parts of water to obtain the desired inorganic paint.

Electrophoretically depositable paint D

A mixture of 200 parts of an epoxy resin, 55 parts of methanol, 2.5 parts of tin (I!) Chloride and 28 Parts of diethylene glycol are allowed to react at 150 ° C. for 3 hours, a product X being obtained. Separately from this, a mixture of 742 parts of Ν, Ν-dimethylethanolamine, 714 parts of lactic acid and Subjected 300 parts of toluene to the dehydration reaction at 110 ° C. for 4 hours. After adding 245 Parts of boron oxide and 728 parts of neopentyl glycol are added to the reaction mixture for a further 4 hours of dehydration reaction subjected at 120 ° C to give a product Y. To 200 parts of the product X 13 parts of the product are added within 30 minutes at 70 ° C. with stirring. The received Solution is brought to pH 4.5 by adding formic acid and deionized water (1900 parts) set, whereupon a paste is added which is made by dispersing 100 parts of titanium dioxide in 40 parts of the Melamine resin and 60 parts of water has been formed. Here, the desired electrophoresis obtainable paints.

The prepared in the manner described above

ίο inorganic paint C is made with an electrostatic Spray gun on a sheet of stainless steel, an aluminum sheet and a galvanized sheet Mild steel sheet applied so that the paint layer in the dry state has a thickness of about 10 μΐη. the The paint layer is dried at 120 ° C. for 10 minutes. Each coated sheet is subjected to electrophoretic Deposition at 200 V for 2 minutes the paint D applied, the coated Sheet is connected as an anode. The painting is then

Baked for 4 20 minutes at 380 ° C, with a multi-layer Coating system that has a thickness of about 30 μm and a smooth surface is obtained. All coated sheets, d. H. the stainless steel sheet, the aluminum sheet and the mild steel sheet show excellent adhesion between the individual layers of paint.

In comparative experiments (comparative examples 3 and 4), those with the inorganic paint C coated sheets an acrylic resin paint, the 35

■■> <> parts of an acrylic resin, 16 parts of a melamine resin, Contains 25 parts of titanium dioxide, 25 parts of xylene, 5 parts of butanol and 5 parts of butyl acetate by baking or a Epoxy enamel paint is applied by mixing a paste, the 22 parts of an epoxy resin, 28 parts Contains titanium dioxide, 15 parts of xylene, 5 parts of methyl isobutyl ketone and 7 parts of ethyl cellosolve, with 9 parts of a The paint film is then dried The multi-layer paint system has poor adhesive strength and can be used with

Tear off with a tear-off test using adhesive strips based on regenerated cellulose.

The properties of the paint from the products prepared according to Example 2 on galvanized Mild steel sheet and aluminum sheet are used with the

b5 Properties of paints (thickness of paint about 30μπι) compared to the order of a heat-curable acrylic resin varnish, which has been cross-linked with melamine, on galvanized mild steel sheet (

same example 5) and aluminum sheet (comparative example 6), the first with the electrophoretically depositable Paint D have been coated,

have been manufactured. The results are given in Table 2.

Table 2 Test method Galvanized mild steel sheet Product of Aluminum sheet on paint layer Cracking Product of test Product of Comparison Product of numerous cracks Well Comparison Example 2 example 5 Example 2 Blistering example 6 Cracking and grate lengthways Cracking as in example 1 fine cracking fine cracking the incised Folding test DuPont method t part Well Impact strength (Diameter 12.7 mm) Imperfections Blistering Crack formation 300 g x 50 cm Well Well more inorganic painting Painting remains - 500 g x 30 cm Cracking disappears obtain Blistering as in example 1 well, rust on on the ge Salt spray test the snug velvet sample part strong blisters as in example 1 Well education Salt dip test painting as in example 1 more inorganic disappears Flame retardant Painting remains speed obtain

Example 3
Inorganic paint E.

The desired inorganic paint is obtained by mixing 100 parts of that used in Example 2 Inorganic paint C described above was prepared with 3 parts of a resin emulsion.

The inorganic paint E is applied to a degreased steel sheet with an electrostatic Spray system applied so that the paint layer in the dry state has a thickness of 10 μΐη. the The paint layer is dried at 120 ° C. for 10 minutes. The electrophoresis is applied to the coated steel sheet.

Table 3

table-depositable paint D applied in the manner described in Example 2, followed by the paint layer Is dried at 180 ° C for 20 minutes. This is a two-layer paint system with a thickness

r> obtained from about 30 μm.

The properties of the paint system produced in this way are compared with the properties of the Paint system (Comparative Example 7) compared that by applying the inorganic paint C and of the electrophoretically depositable paint D on a degreased steel sheet to that in Example 2 described way has been produced. The results are given in Table 3:

Test method

Implementation of the
Testing

Product of
Example 3

Product of
Comparative example 7th

Folding test as in example 1 Well fine cracking Impact strength DuPont method Well Cracking (Diameter 12.7 mm) 500 g x 50 cm Salt spray test as in example 1 Well Well

As the above results show, the properties of the two-layer paint system, z. B. the flexibility by adding a small amount Amount of an organic resin can be improved.

Example 4
Inorganic paint F

The desired inorganic paint becomes

by mixing 70 parts of lithium silicate, 30 parts obtained colloidal silica and 100 parts of water.

Electrophoretically depositable paint G

ho A mixture of 30 parts of methyl methacrylate, 25 parts of ethyl acrylate, 30 parts of n-butyl acrylate, 10 parts of 2-hydroxy-n-propyl acrylate, 6 parts of methacrylic acid and 1 part of benzoyl peroxide is added dropwise over 4 hours at 130 ^° C. to a solvent

μ mix of 30 parts of butyl cellosolve and 20 parts Added n-butyl alcohol, being a resinous product is obtained. 61 parts of the product are made i75 parts by adding deionized water) and 2

Parts of diethylamine partially neutralized, whereupon 21 parts of a melamine resin, 18 parts deionized Water and 7 parts of diethylamine are added. The resulting mixture is made up with deionized water diluted to a nonvolatile solids content of 12% by weight, the desired being electrophoretically depositable paint is obtained.

A mild steel sheet that has been degreased and roughened with sandpaper is put into the inorganic paint F immersed, in which the steel sheet is connected as a cathode, whereupon a current of 10 V for 10 seconds applied and the inorganic paint is deposited in a thickness of about 2-3 μm. To Rinsing with water, the coated sheet is poured into the electrophoretically separable paint G

immersed, in which the steel sheet is connected as a cathode, whereupon a current of 80 V is passed through for 3 minutes and thereby the steel sheet is coated. The steel sheet is rinsed with water and the paint layer baked for 20 minutes at 19O ⁰ C, wherein a two-layer coating system is obtained a thickness of about 20 μΐη.

The properties of the paint layer prepared in the manner described above are determined with a 20 μσι thick layer of paint (comparative example 8) compared that by electrodeposition of the electrodepositable paint G was made on the same mild steel sheet. The results are given in Table 4.

Table 4 Implementation of the
Testing Product of
Example 4 Product of
Comparative example 8th Test method Pencil hardness F-H HB Hardness of
Painting DuPont method
(Diameter 12.7 mm)
500 gx 30 cm Well Well Blow
toughness Treatment with the
Salt spray tester for
200 hours slight deterioration
ting of the adhesive strength
speed, no rust Formation of fault
put, deterioration
extension of detention
strength, rust spots Salt spray test

Example 5

Inorganic paint H
50% aqueous solution of

monobasic magnesium phosphate 10 parts

50% aqueous solution of
monobasic aluminum phosphate 10 parts

Water 80 parts

The desired inorganic paint is obtained by mixing the above-mentioned ingredients obtain.

A degreased Flußstahlblech is coated with the inorganic paint H by being immersed at 4O ⁰ C. The coated sheet is left to stand for 15 minutes and then dried at 150 ° C. for 15 minutes. The applied inorganic paint has a thickness of about 2 to 3 μm. The coated metal sheet is coated with the electrophoretically depositable paint B used in Example 1 by applying a current of 220 V for 2 minutes , after which the paint layer is baked ^{at 180 ° C. for 30 minutes.} Here, a two-layer paint system with a thickness of about 20 μm is obtained.

The paint produced in this way has properties similar to those obtained by electrophoretic deposition of the electrodepositable paint B onto a zinc phosphate chemically treated mild steel sheet made painting and better properties than painting made by electrophoretic deposition of the electrophoretically depositable paint B has been produced on a mild steel sheet chemically pretreated with iron phosphate

The product prepared according to Example 5 contains

no heavy metal, so that with it the risk of water contamination compared to the zinc phosphate ; ") phat chemically pretreated subsoil is extremely low.

Example 6
Inorganic paint S

Colloidal silica! 0 parts
50% aqueous solution of

monobasic aluminum phosphate 15 parts

Water 55 parts

The desired inorganic paint is obtained by mixing the above-mentioned ingredients obtain.

The inorganic paint S is applied by dipping on a degreased mild steel sheet. The paint film formed is ^{dried for 10 minutes at 100 °} C., an inorganic paint layer being obtained which, in the dry state, has a thickness of 3 to 5 μm. The coated sheet is immersed in the electrophoretically depositable paint N described in Example 8, whereupon the electrophoretic deposition is carried out at 200 V for 3 minutes. The paint film formed is baked for 30 minutes at 17O ⁰ C with a two-layer coating system is obtained a thickness of about 22 μηι.

The properties of the coating prepared in this manner are compared with the properties of about 20 μπι thick paint (Comparative Example 14) which has been prepared by application of the electrophoretically deposited cash paint N by electrophoretic deposition on a chemically treated with zinc phosphate Flußstahiblech The results are in Table 9 named

24 15th execution 32 593 16 of the test Table 9 as in example 1 Product of Test method DuPont method Product of Comparative example 14th (Diameter 12.7 mm) Example 13 Well Folding test 500 g x 50 cm Well Well Impact resistant as in example 1 Well ability test deterioration Salt spray test Deterioration rate of the adhesive strength Longitudinal adhesive strength along the of the constricted Part cut part in 2 mm width in 10 mm width

Claims (1)

Patent claims: 1. A method for applying layers of paint to conductive materials, characterized in that that one an inorganic paint, the at least one material based on Silicic acid and / or monobasic phosphate or sesquiphosphate of magnesium, calcium or Contains aluminum, on the conductive material to form an inorganic paint layer and then on this layer of paint an electrodepositable paint applied by electrophoresis to form an organic paint layer IO