GB1595400A

GB1595400A - Surface-coating binder for cathodic electrocoating

Info

Publication number: GB1595400A
Application number: GB10224/78A
Authority: GB
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 1977-03-16
Filing date: 1978-03-15
Publication date: 1981-08-12
Also published as: BE864953A; IT7820767A0; DE2711385A1; IT1095465B; FR2384011A1; JPS53113840A

Description

(54) SURFACE-COATING BINDER FOR CATHODIC ELECTROCOATING (71) We, BASF AKTIENGESELL SCHAFT, a German Joint Stock Company of 6700 Ludwigshafen, Federal Republic of Germany, db hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following Statement:- The present invention relates to surfacecoating binders for cathodic electrocoating, which binders have been obtained by reacting Mannich bases with epoxy resins and are converted into their water-dilutable form by protonizing with an acid.

In recent years, a number of binder systems for cationic electrocoating have been proposed, for example in German Laid-Open Applications DOS 2,033,770, DOS 2,163,143, DOS 2,057,799, DOS 1,930,949, and DOS 2,252,536; these give good results in respect of, for example, corrosion protection or throwing power, but are unsatisfactory if the totality of binder properties is considered.

A substantial shortcoming of the conventional systems is, inter alia, that they cannot be processed in the pH range of from 7 to 9 used for anodic electrocoating (cf. also "Electro-deposition of Coatings Advances in Chemistry Series 119, pages 110--127, American Chemical Society, Washington 1973, and Industrial Finishing, 49, No. 8 (1973), pages 18-23).

It is a further disadvantage that the stated crosslinking reactions do not match the desired pH range and that the stability of the baths is only moderate, which is partially responsible for the fact that the bath temperature must be kept low, for example < 25bC, which measure entails greater cost of cooling. The addition of solvents in order to stabilize the baths is undesirable, since greater control becomes necessary and furthermore the binder properties are adversely affected.

German Laid-Open Applications DOS 2,320,301, 2,357,075 and 2,419,179 disclose binders for cationic electrocoating finishes which inter alia exhibit very good corrosion protection and which can be deposited at an alkaline pH of above 7. These binders are reaction products of Mannich bases, obtained from condensed phenols, secondary amines and formaldehyde, with epoxy resins. Essentially, the o diethanolaminomethyl - phenol group or the o - alkylethanolaminomethyl - phenol group of the Mannich base is responsible for the crosslinking on baking the finishes.

However, it is a disadvantage of these systems that amines are split off on baking.

The present invention seeks to provide surface-coating binders for cationic electrocoating finishes, which substantially meet the requirements in respect of the above binder properties and which, on baking, exhibit little or no odor nuisance due to splitting off of amines. If possible, the pH of the surface-coating bath should be from 7 to 9 because, if the product is to be usable in the conventionally available processing installations, the surface-coating bath must have a pH of at least 7.

According to the present invention, there is provided a surface-coating binder for cathodic electrocoating, based on a substantially epoxide-free protonized selfcrosslinking reaction product of a Mannich base and an epoxy resin, which reaction product has been prepared by reacting (A) from 25 to 90% by weight of a reaction product of (a,) a Mannich condensation product of one or more phenols and/or alkylphenols with a primary amine and formaldehyde or a formaldehyde donor, which may or may not be partially replaced by (a2), where (a2) is a monohydric or polyhydric phenol containing one or more ether groups and two or more aromatic radicals, the hydroxyl group(s) of the phenol being optionally reacted with an isocyanate or blocked isocyanate or a carboxylic acid, (b) one or more secondary amines which contain one or more hydroxyalkyl groups and (c) formaldehyde or a formaldehyde donor, with (B) from 75 to 10% by weight of one or more epoxy resins and/or one or more epoxy resin derivatives containing blocked isocyanate groups.

Particularly advantageous embodiments are those wherein the binder has been obtained by reacting from 40 to 80% by weight of component (A) with from 60 to 20% by weight of component (B) and contains from 0 to 30% by weight of another surface-coating binder.

Further preferred features are that the components (A) and (B) are reacted with one another in a ratio such that from 0.2 to 0.9 epoxide group of component (B) is provided per phenolic hydroxyl group of component (A), that the Mannich condensation product (at) employed is a reaction product of nonylphenol or p-tert.butylphenol and phenol with ethanolamine and formaldehyde, component (b) is diethanolamine, and component (B) is a reaction product of bisphenol A or pentaerythritol with epichlorohydrin.

The surface-coating binders of the invention may be converted to their waterdilutable form in the conventional manner by protonizing with an acid.

The following details may be noted in respect of the individual components of surface-coating binders according to the invention.

Components for the synthesis of reaction product (A): (at) is, according to the invention, a Mannich condensation product of one or more phenols and/or alkylphenols, a primary amine and formaldehyde or a formaldehyde donor.

Suitable phenols are phenol itself or alkylphenols, preferably monoalkylphenols where alkyl is straight-chain, branched or cyclic and is of I to 18, especially of 3 to 12, carbon atoms, e.g. hexylphenol, nonylphenol, dodecylphenol, tert.

butylphenol and phenylphenol.

Nonylphenol (including technical - grade nonylphenol containing 85% of 4 nonylphenol) and p - tert. - butylphenol, and mixtures of these alkylphenols with phenol, are preferred. Part of the unsubstituted phenol can also be replaced by bisphenol A. Suitable primary amines are monoalkylamines where alkyl is straight chain, branced or cyclic and is of 2 to 13, preferably of 2 to 6, carbon atoms, e.g.

butylamine, hexylamine and octylamine, as well as hydroxy-substituted and alkoxy substituted monoalkylamines, e.g.

monoethanolamine and mono isopropanolamine, 2 - alkoxyethylamines, such as 2 - methoxyethylamine and 2 - ethoxyethylamine, and mixtures of the said amines.

To prepare component (at), the phenol and/or alkylphenol, primary amine and formaldehyde or formaldehyde donor are reacted with one another, advantageously in such amounts as to provide at least 1 mole of the primary amine per 2 moles of phenol and/or alkylphenol, corresponding to a minimum amount of 2 moles of formaldehyde.

Up to 80% by weight of component (at) can be replaced by a monohydric or polyhydric phenol (a2) which contains one or more ether groups and two or more aromatic radicals.

(a2) Suitable polynuclear phenols which contain one or more ether groups and one or more phenolic hydroxyl groups per molecule include products of the general formula HO--BB--[[--OO-E-O-] .--H or HO-B-[-O-E-O-] P where B is

and X is a straight-chain or branched divalent aliphatic radical of I to 3 carbon atoms or is > So2, > SO, > C=O or --OO-, E is a radical which contains OH groups and is obtained by adduct formation of an epoxy compound with a phenolic OH group, P is a phenol or alkylphenol radical, and n is an integer from I to 3, preferred epoxy compounds used for E being the glycidyl ethers of bisphenol A, pentaerythritol, glycerol, trimethylolpropane, glycol, glycol ethers and other polyhydric, preferably dihydric, trihydric and tetrahydric, alcohols.

Other suitable compounds containing epoxide groups are nitrogen-containing diepoxides, as described in U. S. Patent 3,365,471, epoxy resins obtained from 1,1 methylene - bis - (5 - substituted hydantoin) (U. S. Patent 3,391,097), diepoxides from bis - imides (U. S. Patent 3,450,711), epoxidized aminomethyl diphenyl oxides (U. S. Patent 3,312,664), epoxidized oils, epoxidized polybutadiene oils, heterocyclic N,N' - diglycidyl compounds (U. S. Patent 3,503,979) aminoepoxyphosphonates (British Patent 1,172,916) and 1,3,5 - triglycidyl isocyanurate, as well as epoxy compounds, e.g. dicyclopentadiene dioxide and limonene dioxide. Component (a2) contains hydroxyl groups bonded to aliphatic carbon.

In part, these are formed from the epoxide groups of the epoxy resins (E) on reaction with the bisphenols (B) and/or with the phenols (P). However, the epoxy resins may themselves already contain hydroxyl groups if they have been prepared by reacting alcohols of more than two OH groups (e.g.

pentaerythritol, trimethylolpropane or glycerol) with 2 moles of epichlorohydrin.

A modification of component (a2) which at times proves very useful may be achieved by reacting its hydroxyl groups, which are bonded to aliphatic carbon, with isocyanates or blocked isocyanates, or by esterifying them with a carboxylic acid.

Particularly preferred components (a,) are the reaction products, which contain phenol groups and are virtually free from epoxide groups, of glycidyl ethers of bisphenol A or of polyhydric aliphatic alcohols, e.g. pentaerythritol, trimethylolpropane or glycerol, with bisphenol A, which products contain one or more phenolic OH groups per mole of component (a2).

The products in general have molecular weights of from 650 to 1,300 and epoxy values (epoxy group equivalent per 100g) of from 0.004 to 0.01 and can be prepared, for example, at from 170 to 1800C or, if catalyst for the reaction are present, at correspondingly lower temperatures.

(b) Examples of suitable secondary amines (b) which contain one or more hydroxyalkyl groups are alkylethanolamines or alkylisopropanolamines, where alkyl is of 1 to 6 carbon atoms. However, dialkanolamines, especially diethanolamine, and mixtures of these alkanolamines and/or dialkanolamines, are preferred.

The amount of amine chemically incorporated into the total binder is from 7 to 25, preferably from 10 to 20, % by weight.

(c) Suitable components (c) are formaldehyde or formaldehyde donors, which may be employed as such or in the form of a solution in, for example, an alcohol such as i-butanol or in water.

Preferably, component (A) comprises a mixture of (at) and (a2). In that case, the weight ratio of the two components (at) and (a2) is suitably from 1.0: 0.1 to 1.0 5.0.

Component (at) may or may not be prepared in the presence of component (b) and (c). However, it is preferred to prepare component (at) in a separate step, using solely the amounts of formaldehyde required for carrying out the Mannich reaction (as described in U. S. Patent 3,436,373).

The amounts by weight of the component (c) employed are selected to provide at least 1 mole of formaldehyde per mole of secondary amine (b).

The Mannich bases (A) may be prepared in accordance with the conventional methods described in the literature (cf., for example, Houben-Weyl, Methoden der organischen Chemie, volume XI/I, page 731 (1957)), preferably by reaction at from 20 to 80"C. The ratios of the starting materials employed depend on the properties desired in each particular case.

In general, up to 1/2 mole of the primary amine or I mole of the secondary amine can be employed per phenolic hydroxyl group.

However, it may also be useful to employ larger amounts of component (c), the amount only being restricted by the desired low residual formaldehyde content of the binder.

The amount of component (A) employed in preparing the surface-coating binder according to the invention, is from 25 to 90, preferably from 40 to 80, % by weight of the total amount of (A)+(B).

(B) Preferred epoxy resins (B) are polyepoxide compounds with from 2 to 3 epoxide groups per molecule, e.g. reaction products of polyhydric phenols, especially those of the formula

mentioned under (a2), with epichlorohydrin, but also the above reaction products of polyhydric alcohols, e.g. pentaerythritol, trimethylolpropane or glycerol with epichlorohydrin, as well as reaction products, containing e oxide groups, of epoxy resins with secondary amines or with hydroxyl-containing glycol ethers, and also epoxy resins which contain chemically bonded hetero atoms, e.g. sulfur. In principle, however, monoepoxide compounds can also be used to prepare the binders, especially if component (A) already possesses a pronounced resinous character, i.e. has the requisite molecular weight and degree of branching.

The epoxy resins (b) in general also contain hydroxyl groups bonded to aliphatic carbon, especially if, during the reaction of the polyhydric alcohol, a condensation to give higher molecular weight products has occurred. As already described in connection with component (at), these hydroxyl groups can also be subjected to, for example, reactions with isocyanates or modified, especially partially blocked, isocyanates, and binders having highly desirable properties may be obtainable in this way.

The reaction of from 25 to 90, preferably from 40 to 80, % by weight of component (A) with from 75 to 10, preferably from 20 to 60, % by weight of component (B) is in general carried out at from 20 to. 1000C, preferably from 40 to 1000C, preferably in the presence of an organic solvent, e.g. an alcohol, glycol ether or ketone.

In the case of the reaction of the Mannich base (A) with the epoxy resin (B), the main reaction is assumed to be an autocatalyzed etherification of the phenolic hydroxyl groups by the epoxide groups.

It is essential that the reaction product obtained from components (A) and (B) is substantially free from epoxide groups, i.e.

contains not more than 0.3, and preferably less than 0.1, epoxide group per molecule of reaction product. Advantageously, the components are reacted so as to provide from 0.2 to 0.9, preferably from 0.3 to 0.7, dioxide group of component (B) per phenolic hydroxyl group of component (A).

If the epoxide groups of component (B) are present in excess, they can be removed, at any desired stage, by suitable reaction with, for example, acids, amines or, preferably, mercaptans, e.g. mercaptoethanol or dodecylmercaptan. In every case, the binders according to the invention contain terminal phenolic OH groups, e.g. odiethanolaminomethylphenol groups.

It can be a particular advantage of cationic electro-coating binders within the invention that in order to enable them to be used in the conventional manner for methods based on electrophoresis, they are protonized with only small amounts of a mineral acid, e.g. phosphoric acid, or of an organic acid, for example preferably acetic acid (from 0.1 to 2.5% by weight) and give stable dispersions or colloidal dispersions having a pH of from 6.5 to 10.2, and that the can advantageously be processed without additional solvents or levelling agents being present. A further particular advantage of the cationic electrocoating binders of the invention is that they exhibit excellent wet film adhesion, even over a prolonged period of aging of the bath.A further particular advantage of the binders is that on aging at 300C the bath exhibits good stability, and that on baking the surface coatings, only a very slight odor nuisance results.

The aqueous solutions or dispersions of the surface-coating binders, which are at least partially present in the form of a salt of a water-soluble carboxylic acid, may in addition contain other assistants which can be cathodically deposited, for example other binders (e.g. epoxy resin derivatives modified with partially blocked isocyanates), pigments, fillers, soluble dyes, solvents, levelling improvers, stabilizers, curing catalysts or anti-foam agents.

The protonized surface-coating binders are preferably used for the cathodic electrocoating of electrically conductive surfaces, for example of metal articles, e.g.

brass, copper, aluminum, iron and steel sheets, which may or may not have been chemically pretreated, e.g. phosphatized.

For cathodic electrocoating, the solids content is in general brought to from 5 to 20% by weight by dilution with deionized water. Coating is carried out at from 15 to 40"C for from I to 2 minutes at a pH of the bath of from 6.5 to 10.2, preferably from 7.0 to 9.0, and with a deposition potential of from 50 to 500 volt. The film which has been cathodically deposited on the electrically conductive article is then rinsed with water in the conventional manner. It has been found that the ease of rinsing of the coatings obtained with binders within the invention is substantially better than that of coatings obtained with conventional binders for cathodic coating. This manifests itself, for example, in rinsing requiring substantially less water, and a shorter time.After the film which has been cathodically deposited on the electrically conductive article has been rinsed, it is cured at from about 160 to 220"C for from 10 to 30 minutes, preferably at from 170 to 2000 for 20 minutes.

When applied to substrates, finishes within the invention give smooth coatings having good mechanical properties; in particular, they exhibit great hardness and scratch resistance coupled with good flexibility and firm adhesion. They also exhibit solvent resistance and particularly high resistance to the salt spray test.

In the Examples, parts and percentages are by weight.

EXAMPLE 1 94 parts of phenol, 110 parts of technicalgrade nonylphenol, containing about 85% of 4-nonylphenol (from Fluka AG), 61 parts of ethanolamine and 63 parts of paraformaldehyde in 147 parts of isopropanol are reacted under nitrogen for 2 hours at 76"C. 105 parts of diethanolamine, 81 parts of paraformaldehyde and 200 parts of isopropanol are then added and the mixture is kept at 700 for a further 2 hours.

188.6 parts of a diglycidyl ether based on bisphenol A and epichlorohydrin and having an epoxy value of 0.21, and 75.4 parts of a glycidyl ether based on pentaerythritol and epichlorohydrin and having an epoxy value of 0.60 are then added and reacted for 6 hours at 700 C.

The batch is then concentrated to a solids content of 68% under reduced pressure at an internal temperature of from 50 to 600 C.

To prepare a 1.4 liter electrocoating bath having a solids content of 10%, 206 parts of the binder are protonized with 2.1 parts of glacial acetic acid and diluted with fully demineralized water (the final pH of the bath is 8.5). After stirring the bath (for 48 hours at 300 C), phosphatized steel sheets are coated for 2 minutes at 200 V/30"C and the coating is baked for 20 minutes at 190"C.

The odor nuisance is substantially less then in the case of binders which were prepared using dialkylamines.

The coatings obtained are smooth, hard and solvent-resistant, and withstand flexing; they are from 12 to 13 ssm thick and after 10 days' exposure to the salt spray test they show an attack of from 3 to 4 mm.

EXAMPLE 2 94 parts of phenol, 110 parts of nonylphenol, 146 parts of a polyphenol containing ether groups (prepared as described in Example 1 of German Laid Open Application DOS 2,419,179) having a solids content of 70%, 61 parts of ethanolamine and 116 parts of diethanolamine in 300 parts of isopropanol are reacted with 144 parts of paraformaldehyde under nitrogen at 70"C for 2 hours.

Thereafter, the same amounts of glycidyl ether as in Example 1 are added and the mixture is reacted for 6 hours at 70"C. 204 parts of the binder, concentrated to a solids content of 69%, are protonized with 3 parts of glacial acetic acid and diluted to give a 10% strength electrocoating bath with 1.4 liters of fully demineralized water (pH 8.2).

After stirring for 24 hours at 300C in order substantially to remove organic solvent, phosphatized steel sheets are coated for 2 minutes at 150 V/30 C. On baking, substantially less odor nuisance results than when using corresponding binders prepared with dialkylamines. The flawless coatings which have been cured for 20 minutes at 1900C are from 12 to 13 ,um thick and after 10 days' exposure to the salt spray test show an attack of from 1 to 3 mm.

This test was carried out on zinc phosphatized sheets which had not been aftertreated with chromic acid.

WHAT WE CLAIM IS: 1. A surface-coating binder for the cathodic electrocoating of electrically conductive surfaces, comprising a substantially epoxide-free protonized selfcrosslinking reaction product of a Mannich base and an epoxy resin, wherein the reaction product has been prepared by reacting (A) from 25 to 90% by weight of a reaction product of (at) a Mannich condensation product of one or more phenols and/or alkylphenols with a primary amine and formaldehyde or a formaldehyde donor, which may or may not be partially replaced by (a2), where (a2) is a monohydric or polyhydric phenol containing one or more ether groups and two or more aromatic radicals, the hydroxyl group(s) of the phenol being optionally reacted with an isocyanate or blocked isocyanate or a carboxylic acid, (b) one or more secondary amines which containne or more hydroxyalkyl groups and (c) formaldehyde or a formaldehyde donor, with (B) from 75 to 10% by weight of one or more epoxy resins and/or one or more epoxy resin derivatives containing blocked isocyanate groups.

2. A surface-coating binder as claimed in claim 1, wherein the components (A) and (B) are reacted with one another in a ratio such that from 0.2 to 0.9 epoxide group of component (B) is provided per phenolic hydroxyl group of component (A).

3. A surface-coating binder as claimed in claim 1 or 2, wherein a reaction product of one or more phenols selected from nonylphenol, dodecylphenol, p-tert.butylphenol and phenol with ethanolamine and formaldehyde is employed as the Mannich condensation product (a,).

4. A surface-coating binder as claimed in any of claims 1 to 3, wherein diethanolamine is used as component (b).

5. A surface-coating binder as claimed in any of claims 1 to 4, wherein a reaction product of bisphenol A or pentaerythritol with epichlorohydrin is used as component (B).

6. A surface-coating binder as claimed in any of claims 1 to 5, wherein the weight ratio of the components (a1)/(a2) is from 1 0.1 to 1 . 5.

7. A surface-coating binder as claimed in claim 1 and substantially as described in any of the foregoing Examples.

8. A surface-coating composition for the cathodic electro-coating of electrically conductive surfaces comprising a binder as claimed in any of claims 1 to 7 in aqueous solution or dispersion.

9. A process for the cathodic electrocoating of electrically conductive surfaces wherein a bath comprising a surface coating composition as claimed in claim 11 is used for the electrocoating.

10. A process as claimed in claim 9, wherein the bath has a pH of from 7 to 9.

11. A process as claimed in claim 9 or 10, wherein a metal surface is cathodically electrocoated in an aqueous bath having a solids content of from 5 to 20% by weight at a temperature of from 15 to 400C for from I to 2 minutes using a deposition voltage of from 50 to 500 volts, whereupon the

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **.

The odor nuisance is substantially less then in the case of binders which were prepared using dialkylamines.

The coatings obtained are smooth, hard and solvent-resistant, and withstand flexing; they are from 12 to 13 ssm thick and after 10 days' exposure to the salt spray test they show an attack of from 3 to 4 mm.

EXAMPLE 2

94 parts of phenol, 110 parts of nonylphenol, 146 parts of a polyphenol containing ether groups (prepared as described in Example 1 of German Laid Open Application DOS 2,419,179) having a solids content of 70%, 61 parts of ethanolamine and 116 parts of diethanolamine in 300 parts of isopropanol are reacted with 144 parts of paraformaldehyde under nitrogen at 70"C for 2 hours.

Thereafter, the same amounts of glycidyl ether as in Example 1 are added and the mixture is reacted for 6 hours at 70"C. 204 parts of the binder, concentrated to a solids content of 69%, are protonized with 3 parts of glacial acetic acid and diluted to give a 10% strength electrocoating bath with 1.4 liters of fully demineralized water (pH 8.2).

After stirring for 24 hours at 300C in order substantially to remove organic solvent, phosphatized steel sheets are coated for 2 minutes at 150 V/30 C. On baking, substantially less odor nuisance results than when using corresponding binders prepared with dialkylamines. The flawless coatings which have been cured for 20 minutes at 1900C are from 12 to 13 ,um thick and after 10 days' exposure to the salt spray test show an attack of from 1 to 3 mm.

This test was carried out on zinc phosphatized sheets which had not been aftertreated with chromic acid.

WHAT WE CLAIM IS: 1. A surface-coating binder for the cathodic electrocoating of electrically conductive surfaces, comprising a substantially epoxide-free protonized selfcrosslinking reaction product of a Mannich base and an epoxy resin, wherein the reaction product has been prepared by reacting (A) from 25 to 90% by weight of a reaction product of (at) a Mannich condensation product of one or more phenols and/or alkylphenols with a primary amine and formaldehyde or a formaldehyde donor, which may or may not be partially replaced by (a2), where (a2) is a monohydric or polyhydric phenol containing one or more ether groups and two or more aromatic radicals, the hydroxyl group(s) of the phenol being optionally reacted with an isocyanate or blocked isocyanate or a carboxylic acid, (b) one or more secondary amines which containne or more hydroxyalkyl groups and (c) formaldehyde or a formaldehyde donor, with (B) from 75 to 10% by weight of one or more epoxy resins and/or one or more epoxy resin derivatives containing blocked isocyanate groups.
2. A surface-coating binder as claimed in claim 1, wherein the components (A) and (B) are reacted with one another in a ratio such that from 0.2 to 0.9 epoxide group of component (B) is provided per phenolic hydroxyl group of component (A).
3. A surface-coating binder as claimed in claim 1 or 2, wherein a reaction product of one or more phenols selected from nonylphenol, dodecylphenol, p-tert.butylphenol and phenol with ethanolamine and formaldehyde is employed as the Mannich condensation product (a,).
4. A surface-coating binder as claimed in any of claims 1 to 3, wherein diethanolamine is used as component (b).
5. A surface-coating binder as claimed in any of claims 1 to 4, wherein a reaction product of bisphenol A or pentaerythritol with epichlorohydrin is used as component (B).
6. A surface-coating binder as claimed in any of claims 1 to 5, wherein the weight ratio of the components (a1)/(a2) is from 1 0.1 to 1 . 5.
7. A surface-coating binder as claimed in claim 1 and substantially as described in any of the foregoing Examples.
8. A surface-coating composition for the cathodic electro-coating of electrically conductive surfaces comprising a binder as claimed in any of claims 1 to 7 in aqueous solution or dispersion.
9. A process for the cathodic electrocoating of electrically conductive surfaces wherein a bath comprising a surface coating composition as claimed in claim 11 is used for the electrocoating.
10. A process as claimed in claim 9, wherein the bath has a pH of from 7 to 9.
11. A process as claimed in claim 9 or 10, wherein a metal surface is cathodically electrocoated in an aqueous bath having a solids content of from 5 to 20% by weight at a temperature of from 15 to 400C for from I to 2 minutes using a deposition voltage of from 50 to 500 volts, whereupon the

adhering film thus produced is rinsed and cured at from 160 to 220"C for from 10 to 30 minutes.
12. Articles which have been electrocoated by means of a process as claimed in any of claims 9 to 11.