DE1930949C3 - Cathodically depositable coating agents - Google Patents

Description

The present invention relates to cathodically depositable coating media which are at least partially contain a condensation product containing basic nitrogen groups neutralized with a carboxylic acid.

Compared to the process of anodic deposition 4 <> formation of coatings in which salts of polymers containing carboxyl groups are usually used, the method of cathodic deposition of coatings has the advantage that the as Electrically conductive bodies connected to the cathode develop hydrogen, which is the polymer of the superfluous agent hardly adversely affected, while nascent oxygen during the anodic deposition that can chemically change the polymer, and also metal ions in solution which can lead to discoloration of the coatings and reduce the water resistance of the coatings be able.

Process for the production of coatings on electrically conductive bodies, from aqueous solutions or dispersions of salts of nitrogen-based cationic polymers, the polymers on the conductive Bodies that are cathodically deposited and then burned in are known from the German Patent specification 12 76 260 and were also in the German Offenlegungsschriften 15 46 840, 15 46 848 and 15 46 854 suggested.

Dis developed so far for cathodic deposition However, coating agents show with regard to the properties of the coatings obtained therewith still have some disadvantages. In particular, the adhesive strength of the coatings on the substrate and their resistance to corrosion were still in need of improvement.

The present invention was therefore based on the object of developing coating compositions which, according to the method of cathodic deposition are advantageous to process and thereby to coatings with lead particularly advantageous properties. In addition to the necessary hardness and elasticity, in particular the adhesive strength of the coatings on the substrate and their corrosion resistance are improved will.

The subject of the present invention is sinus cathodic separable coating agents based on a water-soluble or water-dispersible, at least basic nitrogenous cationic products, some of which are present as a salt of a water-soluble carboxylic acid, characterized in that the product is a condensation product of

a) 40 to 75 percent by weight of a polyfunctional Amino alcohol with tertiary nitrogen atoms, which may contain epoxy groups,

b) 10 to 30 percent by weight of a mixture of 4Ci to 90 percent by weight of a monocarboxylic acid having 7 to 24 carbon atoms and 60 to 10 percent by weight of at least two carboxyl groups per molecule containing adduct, polycondensate or polymer and

c) 5 to 40 percent by weight of at least one customary, optionally etherified with an alcohol Phenoplast or aminoplast resin,

where the sum of the percentages by weight of a) -f b) + c) is equal to 100.

To the structural components of the inventive cationic, nitrogen-based condensation product, the following is to be carried out in detail:

To a) Suitable polyfunctional amino alcohols with tertiary nitrogen atoms are preferably the Reaction products of epoxy resins with secondary amines. Suitable epoxy resins are the usual, especially those that can be considered by etherification of at least two hydroxyl groups functional group-containing compounds, such as polyhydric, especially dihydric alcohols or Phenols obtained with epichlorohydrins or dihalohydrins in the presence of alkali.

Dihydric alcohols or phenols which are suitable for the production of such epoxy resins are, for example to mention glycols, such as ethylene glycol, diethylene glycol, Triethylene glycol, propylene glycol-1,2, propylene glycol-1,3, 1,4-butylene glycol, 1,5-pentanediol, 1,6-hexanediol as well as particularly advantageous dihydric phenols such as resorcinol, pyrocatechol, hydroquinone, 1,4-dihydric naphthalene, Bis (4-hydroxyphenyl) methane, bis (4-hydroxyphenyl) methylphenyl methane, bis (4-hydroxyphenyl) tolyl methane, 4,4'-dihydroxydiphenyl and 2,2-bis (4-hydroxyphenyl) propane.

Polymeric 2,2-bis (4-hydroxyphenyl) propane glycidyl ethers are particularly suitable with an epoxy value of 0.02 to 0.6, preferably between 0.20 and 0.25.

Likewise, polyglycidyl ethers of trihydric and polyhydric alcohols, such as. B. glycerine, Trimethylolpropane, trimethylolethane or pentaerythritol.

The production of such epoxies or epoxy resins and other representatives of this class of substances are in the book by A. M. Paquin "Epoxy Compounds and Epoxy Resins", Springer-Verlag, 1958 (Berlin— Heidelberg-Göttingen).

Suitable secondary amines are the usual, ins- esters of acrylic acid or methacrylic acid with alcohol

special ones that get two identical or different ones with 1 to 8 carbon atoms, (meth) -acryl-

Alkyl residues with 1 to 20 carbon atoms in straight acid amides, vinyl esters, vinyl aromatics, such as. B. Sty-

contain chain or branched arrangement, where rol, polyenes, especially dienes, such as butadiene or

the alkyl radicals in turn have further substituents, ₅ isoprene, and mixtures of these monomers. the

such as B. hydroxyl or alkoxyl groups or halo carboxyl group-containing mixed according to the invention

genes are preferably suitable polymers can additionally contain further copolymeric

secondary amines with hydroxyalkyl groups, such as. B. sizable monomers, such as. B. unsaturated oils, and

Diethanolamine, dnsopropanolamine and di-n-pro oleic acids, e.g. B. Polymerized linseed oil fatty acids

panolamin. _l0 included. The mixture mentioned under b) carboxyl-

Also cyclic secondary amines, such as. B. substances containing pyrroline groups settle to 40 to 90

Din, piperidine or morphoene are to be used for this- weight percent monocarboxylic acid and 60 to 10

the. Percentage by weight of at least a small amount of carboxy-

The epoxy resins are used with the adduct containing secondary groups per molecule, poly-

Amines expediently in a ratio of i ₅ condensate or polymer together; especially

1: 0.5 to 1: 1, preferably from 1: 0.7 to 1: 1, based on a proportion of about 75 percent by weight is advantageous

on epoxy group / amine nitrogen, at temperatures monocarboxylic acid and about 25 percent by weight of poly

from 30 to 150 ° C., in particular from 70 to 120 ° C., to carboxylic acid.

optionally in the presence of solvents which may not be the optionally etherified to c) As a phenoplast or aminoplast, under the reaction conditions to the reactor ₃₉ with an alcohol

tion components can react, such. B. Glycol, the usual ones are suitable, especially the

ether. Since the reaction is exothermic, condensation products of formaldehyde with metal

the amine expediently not all at once, but amine and phenols and mixtures of such condensers

change gradually to the epoxy compound and leave sate. The manufacture of these products is carried out on an ongoing basis react for some time (approx. 30 min). Special 15 borrowed way and is z. B. described in »Chemistry of

ders advantageous z. B. the reaction product from phenolic resins «by K. Hultzsch, Kunststoffrundschau

the condensation polymer from 2,2-bis- (4-hydroxy- 7 (1960), pp. 433 to 440 and J. appl. Pol. Sci. 11 (1967),

phenyD-propane and epichlorohydrin with an epoxy p. 1251 to 1257. Pheno-

_w ert 0.20 to 0.225 and diethanolamine, which in PLAST- or aminoplast condensates, with an absence of solvents at 80 to 120 C 30 alcohol having from 1 to 4, especially 2 to 4 carbon

will be produced. atonia are at least partially etherified.

To b) As monocarboxylic acids with 7 to 24 carbons. The preparation of the condensation product from the

Atoms of matter are aliphatic, aromatic, components a), b) and c) can be with or without additives

araliphatic and polycyclic monocarboxylic acids, a solvent can be made. Purpose-preferred saturated or unsaturated fatty acids 35 moderately, the condensation of the individual components

with 10 to 22 carbon atoms and resin acids in a temperature range of 120 to 250 C,

and mixtures of the monocarboxylic acids mentioned. As carried out in a period of 1 to 6 hours. When

Examples of the solvents to be used according to the invention, if appropriate, are suitable

Carboxylic acids may be mentioned! Carboxylic acids or their z. B. glycol ether.

Mixtures, such as those obtained in the saponification of animal or 40 is particularly advantageous, the polyfunctional vegetable fats or oils, such as amino alcohol a) initially with the z. B. lauric, myristic, palmitic, stearic, oleic, linoleic, carboxylic acid with 7 to 24 carbon atoms as long as linolenic, eleostearic and ricinoleic acid, conversion to about 150 to. To be heated under nitrogen to 200 C, treatment products of natural fatty acids, such as z. B. until the acid number has fallen to a value of <10 isomerized linseed oil fatty acids, dehydrated castor 45 and only then add the at least two carboxyl groups oil fatty acid, hydrogenated oil fatty acids, acids of tall oil per molecule containing adduct, polycondensate or tall oil distillates, resin acids of rosin polymer and up to an acid number of and their modification products. Especially before 5 to be esterified. Namely, if the poly added castor and dehydrated castor oil fatty acids are added first, crosslinking to an acidic product and distilled tall oil with a resin acid no longer acid-soluble product can easily occur. Annoying content of 25 to 30 %. Foaming during the esterification can be avoided by adding at least two carboxyl groups per molecule of a few drops of silicone oil. In the case of adducts, polycondensates or polymeric containing adducts, a viscous clear meltsate is obtained for the purposes of the invention: adducts that are best still in the heat with one of unsaturated carboxylic acids, especially di- 55 crosslinkable phenolic or melamine resin mixed carboxylic acids, compounds containing double bonds and stirred at 50 to 100 ° C. for some time. Especially gebindungen as adducts of maleic acid to be unsuitable resins which only partially soluble in water saturated oils such as? .. as maleinized linseed oil or are.

Polybutadiene oil as disclosed in the British patent specification The condensation product of the invention is

1107 147 described, polycondensates, such as. B. acidic 60 from 40 to 75 percent by weight of component a),

Alkyd resins, the production of which z. B. in the French 10 to 30 percent by weight of component b) and

see patent 14 91 616 or in J. Oil a. CoI. to 30 percent by weight of component c) obtained.

Chem. Assoc. 47 (1964) No. 10, pp. 767 to 798. Particularly preferred are condensation products from

is written, as well as particularly suitable mixed poly 50 to 60 percent by weight of component a), 15 to

merisate of carboxyl-containing monomers, «5 to 25 percent by weight of component b) and 15 to

such as acrylic acid, methacrylic acid, itaconic acid, maleic 30 percent by weight of component c).

Maleic acid half-esters with the usual with particularly advantageous condensate according to the invention

nnnnlvmerizable monomers, such as. B. station products are obtained from, for example

acid,

these copolymerizable monomers, such as. B.

to 60 parts of the polyfunctional amino alcohol with tertiary nitrogen atoms, which consists of 82 to 86 parts an epoxy compound of an epoxy value (= mol £ poxide / 100 g resin) of about>), 2 with 14 to 16 parts Diethanolamine was obtained as component a), 10 to 20 parts of ricinic fatty acid or a tall oil fatty acid / resin acid mixture and 3 to 8 parts of a copolymer of 60 to 80 TeMen acrylic acid and / or methacrylic acid ester, 5 to 15 parts of acrylic acid, 5 to 15 parts of acrylamide and 5 to 15 parts of an isomerized linseed oil or a copolymer from 30 to 40 parts of styrene, 20 to 40 parts of butadiene, 25 to 35 parts of butyl maleate and 5 to 15 parts of tall oil fatty acid / resin acid mixture as component b) and 20 to 30 parts of a commercially available phenolic resin or an etherified one Melamine resin as component c).

To obtain a water-soluble product, the product prepared from components a), b) and c) is added Condensation product adds a sufficient amount of a water-soluble carboxylic acid and dilutes it mU deionized water. The best solution here is the addition of water-soluble, relatively volatile ones Carboxylic acids, such as lower aliphatic carboxylic acids, such as. B. formic acid and acetic acid, or else Dicarboxylic acids.

The aqueous solutions or dispersions of the at least partially as a salt of a water-soluble carboxylic acid Any condensation products present can also be mixed with them by means of cataphoresis Contain electrochemically separable auxiliaries, such as pigments, soluble dyes, high-boiling solvents, Flow improvers, stabilizers, antifoam agents and other auxiliaries and additives.

For the deposition conditions of the cathodically depositable coating media according to the invention what is said in the patent cited above applies. In general, the deposition takes place at temperatures from 15 to 40 C and for a time from 1 to 2 min. After the cathodically deposited film on the electrically conductive body has been rinsed off, it becomes Baked at about 140 to 200 C for 10 to 30 minutes.

The coating compositions according to the invention produce excellent coatings on cathodic deposition mechanical properties, such as great hardness and scratch resistance with good elasticity and strength Adhesion to the metal. They can also be used at high voltages, e.g. B. 350 volts, deposit what to achieve a good wraparound and sufficiently thick layers is very desirable. Furthermore, the Excellent corrosion resistance of the coatings. There is also compatibility with the usual pigments and the gloss of the coatings is good, you can use primers - because of the low yellowing when stoving - also produce light-colored single-layer paintwork on different metals.

Another advantage of the coating agents according to the invention is the complete absence of the so-called Hollow body effect. The hollow body effect is in "Farbe und Lack", vol. 75, year 1969, issue 4 on p. 327 to 336. This is understood to mean that which occurs with many electrically depositable paints Appearance that on the outside of metal surfaces that form a hollow body, surface defects occur in the coating layer. This effect is evident in electrodeposition painting complex shaped bodies are very annoying and difficult to remove. So it's an important one technical progress to have an electrically separable coating agent available that this Disadvantage does not show.

The parts and percentages given in the examples are weight units.

example 1

150 parts of an epoxy resin obtained by reacting 2,2-bis (4-hydroxyphenyl) propane with epichlorohydrin and having an epoxy value of 0.20 to 0.225 and a hydroxyl value of 0.32 are melted at 80 to 90 ° C. 33 parts of diethanolamine were added dropwise with stirring over the course of 30 minutes, the temperature should be about 100.degree. The mixture is then stirred at this temperature for a further ₂ hours. Then 50 parts of ricineal fatty acid (acid number: 196, iodine number: 170, viscosity: 1 poise) are added and the temperature is gradually increased to 180 ° C. The water formed is continuously removed from the reaction vessel with the aid of a stream of nitrogen. To avoid annoying foaming, add a few drops of silicone oil. When the acid number of the mixture has fallen below 5, 15 parts of an 83% copolymer of 50 parts of isobutyl acrylate, 20 parts of methyl methacrylate, 10 parts of acrylic acid, 10 parts of acrylamide and 10 parts of an isomerized linseed oil in isopropanol are added in portions. The temperature is kept at 180 ° C. until the acid number has fallen below 5 again. The mixture is then allowed to cool to about 100 ° C., 50 parts of isopropanol are added and _{the mixture is stirred for 2} hours at 80 ° C. with 190 parts of an approximately 45% strength aqueous solution of a commercially available phenolic resin of the resol type. The fixed salary is 74%. 100 parts of the still warm resin are first stirred with 4.6 parts of glacial acetic acid and then diluted with deionized water to a solids content of 10%. From this solution, a film is deposited cathodically on bare deep-drawn sheet metal for 1 min at 70 volts, which is stoved at 170 ° C. for 20 min. A 20 μm thick, firmly adhering coating is obtained, which is rigid and as hard as a nail and which is about 80% corroded in the salt spray test according to ASTM B 117-64 after 32 days. The flow can be improved by adding 5% decanol to the bath liquid.

Example 2

1050 parts of the epoxy resin mentioned in Example 1 are, as described in Example 1, first with 231 Share diethanolamine implemented. Then 350 parts of a tall oil fraction, which consists of 68% fatty acids, are added and 30% resin acids and has an iodine number of 145 and an acid number of 175. One stirs under a gentle stream of nitrogen at 180 ° C. until the acid number has fallen below 5 is. 115 parts of the 83% strength copolymer from Example 1 are then introduced in portions holds at 180 C until the acid number has dropped below 5 again. Then allowed to cool to 140 C and are 1050 parts of a 55% isobutanolic solution of an almost completely etherified with isobutanol Hexamethylolmelamine is added and the mixture is stirred at 90 ° C. for 1 h. The final solids content of the resin is 87%. 115 g of resin are added one with 0.5 g of decanol and 3 g of glacial acetic acid and diluted to a Festeehall of 10 ° / .. A 2 min at 100 volts

7 8 j

Film cathodically deposited on deep-drawn sheet is *
after 20 minutes of baking at 170 ° C 30 μ thick. Example 4
The film is as hard as nails, adhesive and flexurally stable and holds. As described in Example 2, 600 parts of the ASTM-B-117-64 salt spray test are brought up to 80% strength of the epoxy resin of Example 1 with 132 parts of corrosion of the film for 32 days was standing. A resin pigmented 20% with 5 ethanolamine and 200 parts of the tall oil fraction to give iron oxide red 130 BM was reacted for 2 minutes. 200 parts of a mixer are then deposited at 160 V and polymerized from 35 parts of styrene and 30 parts of maleic baked at 170 ° C. for 20 minutes. The coating is 25 μ thick, nail-like, resistant to bending, acid-n-butyl half-ester, 30 parts of butadiene and 10 has an Erichsen cavity of> 10 and very good Haf parts of the tall oil fraction mentioned and so stirs on the metal. The salt spray test according to ASTM to long under nitrogen at 180 ⁰ C until the acid number <5 it withstands 30 days until 80% corrosion. is. 200 parts of this resin are mixed at about 100.degree

with 120 parts of a 55% n-butanolic solution a n-butanol etherified melamine resin and stir

^Bei P ^{iel 3} for 1 h at 90 ⁰ C. The Endfestgehalt is 33%. 120 parts

As described in Example 2, 150 parts of this resin are added in succession with 6.3 parts

of the epoxy resin described in Example 1, 33 parts of glacial acetic acid and deionized water and provides a

Diethanolamine and 50 parts of the described tall oil solids content of 10%. The 2 min at 140 volts

fraction at. Thereupon 35 parts of a maleini deep-drawn sheet are deposited film for 20 min

overbased linseed oil baked having a maleic anhydride 17O ⁰ C. One obtains a 16 μ thick,

of 7% and stir under stick material for so long with a rigid, adhesive, nail-hard coating of good quality

180 ° C to an acid number of <5 is reached. Man course. It passes the ASTM-B-117-64 salt spray test

lets cool to about 100 ⁰ C and mixes with 160 parts up to 80% corrosion stood for 22 days,

len a 55% isobutanolic solution of an iso-. .

butanol-etherified melamine resin. The final solids content of example 5

is 84%. 120 parts of the resin are mixed with 6.4 35 The condensation product of Example 4 is how

Share glacial acetic acid and dilute with water to a described there, with the isobutanol-etherified MeI-

Fixed content of 10%. A boiled for 2 min at 140 volts on deep amine resin from Example 3 and an acetic acid,

Draw sheet cathodically deposited film results after 10% aqueous solution prepared. As in both

20 minutes baking at 170 ⁰ C a 22 μ thick game 4 coating produced has the same mechanical

Coating with very good leveling, good adhesion, the properties of the same as the coating of Example 4

Resistant to bending and as hard as nails and after 28 days of salt a better salt spray resistance according to ASTM

spray test according to ASTM B 117-64 is 80% corroded. 117-64: 28 days.

Claims (1)

Claim: Cathodically depositable coating agent based on a water-soluble or dispersible, Basic nitrogenous acids present at least partially as a salt of a water-soluble carboxylic acid cationic product, characterized in that that the product is a condensation product from ίο a) 40 to 75 percent by weight of a polyfunctional amino alcohol with tertiary nitrogen atoms, which may contain epoxy groups, b) 10 to 30 percent by weight of a mixture of ^1S 40 to 90 percent by weight of a monocarboxylic acid with 7 to 24 carbon atoms and 60 to 10 percent by weight of an adduct, polycondensate or polymer containing at least two carboxyl groups per molecule and c) 5 to 40 percent by weight of at least one optionally etherified with an alcohol, common phenoplast or aminoplast resin, where the sum of the percentages by weight of a) + b) + c) is equal to 100.