DE2325177A1 - HEAT-RESISTANT PAINT IN THE FORM OF AN Aqueous DISPERSION OR SOLUTION - Google Patents

Description

PATENT ADVOCATE DR. HANS-GUNTHER EGGERT ₁ DIPLOMA CHEMIST

5 COLOGNE 51, OBERLÄNDER UFER 90 *.

Cologne, May 17, 1973 Eg / Ax / 94

Shinto Paint Co., Ltd. 1O-73 Minamitsukaguchicho 6-chome, Amagasaki, Japan

Thermosetting paint in the form of an aqueous dispersion or solution.

The ^ invention relates to water-dispersible, heat-curable paint and coating compositions which _s for the job by electrolytic deposition are ₉ are connected in a surface layer on the surface of workpieces and items "the cathode is deposited as a _9".

In the case of coating by electrolytic deposition, it is known to use water-dispersible paints and coating compounds, which are used in the form of an aqueous solution or dispersion as a bath for electrolytic deposition. The most common coating compositions are used for electrodeposition _s, however, contain as main component a resin fumbildende _B containing carboxyl groups. The resin is therefore present in the form of anions in water, and when it is placed in an electrical field it migrates to the anode and is deposited on it.

In this conventional coating by deposition, however alektrolytiache _o u a ", there is the problem that by the circuit to be coated metallic workpiece as the anode daa metal or aur Yorbohand-

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ment applied surface layer of the to be coated

will

Workpiece dissolved in the electrolyte / so that the surface of the workpiece is eroded o If, for example, an iron object is to be coated as a workpiece, the iron is dissolved out »It is present as an oxide in the electrolytically deposited surface layer and causes an undesirable coloration of the deposited resin film _Φ If that If the workpiece is provided with a phosphate coating, part of the phosphate coating is also dissolved during the electrolytic deposition, so that the natural corrosion resistance of the phosphate film can be impaired. In particular, in cases where chrome-plated workpieces are to be coated with a final transparent or clear surface film, the chrome-plated layer is subject to corrosion during the electrodeposition process. Therefore, the surface gloss is deteriorated and the appearance is impaired.

These disadvantages of the conventional electrodeposition process can be eliminated by performing a cathodic electrodeposition in which the workpiece to be coated is connected as the cathode. For such cathodic electrodeposition, however, 'a' resin (the main film-forming component) must be used which is effective as a cation after dispersion or dissolution in water, so that it migrates to the cathode and is deposited on the cathode (workpiece to be coated) when it is brought into an electric field be introduced chemically bonded basic groups in the resin _e, when the resin is dissolved in an acidic aqueous medium, or dispersed, the basic groups are dissociated into cations. For this purpose, various coating compounds have been proposed which are suitable for the cathodic elec-

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trolytic separation. The usual paints and coating compounds harden only insufficiently, so that it is difficult to form surface layers, which have completely satisfactory properties.

The invention is a coating composition that Not only suitable as an ordinary paint, but also for cathodic electrodeposition and can be cured properly under normal conditions.

The water-dispersible, thermosetting paints and coating compositions according to the invention consist of water, a water-soluble organic and / or inorganic acid and a resin material which has been prepared by reacting a secondary amine with epoxy groups which are present on the main chain of a copolymer consisting of 5 to 50 wt .- £ of an epoxy group-containing monomers, ethylenically unsaturated und'50 to 95 wt -.% of one or more vinyl or acrylic monomers untesättigter * which do not contain epoxy groups and are copolymerizable with the ethylenically unsaturated monomers! ,, where the secondary amine is used in an amount of 0.1 to 1.0 equivalent per equivalent of the epoxy groups.

After dissolution or dispersion in water, the resin, material in the paints and coatings according to the invention reads in the form of cations, ao dnU oo when passing an electric current aur Knthodo _: migrates and is deposited on the cathode. In addition, the surface layer formed from the paints and coating compositions according to the invention is crosslinked and cured if it is heated to 140 "to 200 C WJj ¹ U ₀ J mi r ^"Ι'ΠΠο Ui TMIm- InL 1IaIiIaI ¹ Ul _{1 for 20 to 60 minutes} J UUÜ

excellent gloss and excellent mechanical properties and chemical resistance.

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One of the monomers for the preparation of the copolymer, which is the most important "basic component of the paints according to the invention, is an ethylenically unsaturated monomer which contains an epoxy group. Examples of suitable for this are glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, MG-lycidyl acrylamide and yinyl epoxydene mono-oxydene Glycidyl methaorylate is particularly preferred in view of the reactivity with the other compound "in copolymerization and availability". The epoxy group-containing ethylenically unsaturated monomer is preferably used in an amount of 5 to 50 wt _o - used the copolymers $>"If its content is less than $ 5, no sufficient dispersibility in water and curability is obtained" If the proportion is higher than 50 $ _} it is difficult to match the various properties of the deposited film to one another. In addition, a large amount of an expensive monomer is economically disadvantageous «

As unsaturated vinyl monomers or acrylic monomers not containing an epoxy group and having the above Epoxy components are copolymerizable, see aromatic vinyl compounds, for example. Styrene and vinyl toluene, Vinyl acetate, acrylonitrile and methacrylonitrile, acrylic acid * « alkyl esters, e.g. Ethyl acrylate, buty ^ acrylate and 2-ethylhexyl acrylate, Methacrylic acid alkyl esters, e.g. Methyl methacrylate and butyl methacrylate, hydroxyalkyl esters of Acrylic acid and methacrylic acid, ζ ο B. 2-hydroxyethyl acrylate and 2-hydroxypropyl methacrylate, and dialkyl esters of unsaturated dibasic acids, e.g. diethyl maleate, Dibutyl fumarate and dibutyl itaconate. Monomers, the one functional group - highly responsive with Contain epoxy groups, e.g. unsaturated carboxylic acids or their anhydrides, for example acrylic acid, methacrylic acid or maleic anhydride or N-methylolacrylamide, cause gel formation through crosslinking during the

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Copolymerization reaction and therefore cannot be used o The particular monomer to be used and the amount in which it is used in the copolymerization depends on the properties of the deposited material Films abo

The copolymers can be prepared according to any generally known process * It is, however, expedient to carry out a radical polymerization using a polymerization initiator which forms free radicals in an organic solvent. The solvent used because of the subsequent dissolution or dispersion of the polymer formed in water _B must - is-preferably a water-miscible solvent _Q Suitable solvents include lower alcohols such _{s e} B _o Xtha == nolß isopropyl alcohol and tert-butyl alcohol _o ~ _fl Glykoläth © r _e zobo Ithylenglykolmonomethyläther ,, Ithylenglykoliaono · = - ethyl ether ₉ Ethylene glycol monoethyl ether and diethylene glycol monoethyl ether _s acetone and diaoet-on alcohol

As frei® Eadikale polymerization initiators can Peraxyde ₀ Bensoylperoxyd ₉ and ZOB However, as expected Cum 13aydrop © © r = _fl oxide veriieadet warden _o with a .Verfärbung is _s when aas Gopolymerisat is subsequently reacted with the amine _s w © © n preferably rd Azo compounds _s ZoB ₀ Azobisisobutyroaitrilj ve.rvjendet,

ι ο

As an example © suitable secondary amines ·, which are pendant to implement with d © n to the backbone of the copolymers before handenen epoxy _s are gsnanntg lower dialkylamine © ₈ S ₀ B ₀ Bim © methylamine _s Mäthylamin di-n = propylaiiin _s Dialkanolamin® and I = Alkylalkaaolaaias _s Z ₀ Bo Diethanoiamiηa Diisopropanolamia and I ^ M © thylathanolamin _B ubd cyclisehe secondary AmInO ₈ S ₀ B ₀ PiperiäiEj ₀ 'Morpholio and l = M®thylpiperasia ₀ Bagüglioh äer Disp © ranol = greediness in V / asssr are the alkanolamines relatively low Meag® is very effective and more advantageous

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The amine is used in an amount of 0.1 "to 1.0 equivalent per equivalent of the epoxy group in the copolymer. If the amount is less than 0.1 equivalent, sufficient dispersibility of the resulting resin in water will not be achieved if it is more than 1.0 equivalent is left unreacted amine _s so that the water resistance and other properties of the final dried and cured coating are impaired «

The reaction of the amine with the epoxy groups can be obtained by heating and stirring the solution already formed of the copolymers with the addition of the amine is carried out "The reaction temperature is preferably in the range of 50 to 120 ⁰ G. When operating below 50 ⁰ C, the reaction rate so low that a long time is required, "If the reaction temperature is above 120 ⁰ * C, the crosslinking (lifting reaction)" negligible "is.

The reacted with the amine resin is dissolved in water ₉ in which an organic or inorganic water-soluble acid has been dissolved, "dissolved or öispergiert, Here, when the solvent used for the copolymerization, and the subsequent reaction with, the amine is miscible with water, its prior removal not necessary. After the acid has been added before the resin solution and mixed well dami.t _s, the water can be gradually added, or the solution may be added to eggs Haralösung in water after the dissolution of the acid. In general, the Haralöaung has a very high viscosity, so that it is easier for mixing to add the water to the resin solution than the Hares solution to the water. "

Suitable organic acids are suitable check "for example Ameisenaäure, acetic acid. Propionic acid. Malonic acid, malonic acid and citric acid ₃ Tartaric acid" Optionally overall

30984971124

mix two or more organic acids or mixtures used with an inorganic acid.

Inorganic acids include "hydrochloric acid, for example, Sulfuric acid and phosphoric acid in question "

The acids and their amounts to be used in each case depend on the intended use of the paints and coating compounds ah »so that no" specific amount range can be prescribed _e 5 ^{1 For} general applications, however, a relatively highly volatile, lower monobasic acid _s ζ _β Β _β formic acid or acetic acid, used in an amount ranging between the basic group bound in the resin (tertiary amino-

.required, amount ^
group) / was up to half of this amount

When using the resin solutions prepared in this manner or dispersions as paints and coating compositions, it is possible ^ additives _s Z used in usual paints ₀ B etc. _t add ₀ pigments, fillers "However, it is to be noted that an additive in the opposite Acids and alkalis is not stable, cannot be used, since the resin itself is basic and its aqueous solution or dispersion is acidic in most cases _e

The paints and coating compositions according to the invention can be applied to any materials such as metal and wood and to other workpieces using any painting method such as brushing, spraying, rolling and dipping. The most beneficial application in terms of their properties be used, however, is the cathodic electrolytic deposition on metallic materials and workpieces. As already mentioned, the cathodic electrodeposition is what is to be coated Workpiece connected as cathode, so that the metal that the workpiece and / or the pretreated surface

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layer (plating, phosphate protective layer or the like) forms, not dissolved during the electrolytic deposition or eroded so that excellent resin precipitates are obtained »is particularly advantageous the electrolytic deposition with the coating compositions according to the invention for the production of white or pastel colored deekschiohten for iron products and from transparent cover films for chrome-plated workpieces and aluminum workpieces.

The invention is further illustrated by the following examples. In these examples, all are parts and percentages based on weight, unless otherwise stated.

example 1

40 parts of isopropyl alcohol and 2 parts of azobisisobutyronitrile were placed in a reactor equipped with a stirrer, reflux condenser, dropping funnel and thermometer and heated. When reflux began, a mixture of 30 parts of glycidyl methacrylate, 5 parts of hydroxyethyl methacrylate, 30 parts of styrene, 35 parts was added 2-ethylhexyl acrylate and 2 parts of azobisisobutyronitrile were added within 2 hours, carried out after which the reaction for another 3 hours under heating at reflux, with a substantially colorless transparent copolymer solution ₀ This Oopolymerlösung were then 5.3 parts of di-n-propylamine was added and 8.4 parts of isopropyl alcohol, after which the reaction carried out for a further 3 hours at the reflux temperature ,. the Härzlösung obtained contained 65 $ · non-volatile components and had a viscosity of 48 poise at 25 ⁰ C. to 154 parts of this resin solution were then 27 parts of a 10% aqueous acetic acid solution and 20 parts of Ä given ethylene glycol monobutyl ether, which was mixed well. Then 466 parts of deionized water were gradually added and mixed in while stirring

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obtain a semi-transparent, stable, liquid dispersion which contained the $ 15 non-volatile component,

Example 2

A copolymer solution was prepared in the manner described in Example 1 using 40 parts of glycidyl methacrylate _, 20 parts of methyl methacrylate ¹ and 40 parts of butyl acrylate as monomers. Then 16 parts of diisopropanolamine and 20 parts of isopropyl alcohol were added to the copolymer solution. The mixture was allowed to react for 3 hours The resin solution obtained contained 65% of the non-volatile component and had a viscosity of 60 poise at 25 ⁰ O ₀ . after mixing well 756 parts of deionized water were gradually added to the mixture _s to give a colorless transparent ivässrige solution containing 10 $ non-flüchtig® · component _c was obtained sathielt "

Example 5

A Oopolymerlösung was prepared in the manner described in Example 1 from 20 parts 20 parts Glycldylnethaorylats Styrolj, 20 parts of methyl methacrylate and 40 part 2-ethylhexyl acrylate as monomers _0. Then x-Jiard®n 5 _E 4 parts of piperidine and 8 ₀ 4 parts of isopropyl alcohol the Gopolymerlösung added _s before the mixture was left to react as in Example 1 @ _o The resin solution obtained contained 65% non-volatile components and had a viscosity of 6.8 poise at 25 ° G _e Aqueous aqueous hydrochloric acid solution and 40 parts of ethylene glycol monobutyl ether ¹ given when mixed well were 7ββ. Partialized water - to dilute the solution 2üges @ ta- | a stable dispersion was not obtained

contained volatile components and was white-cloudy, "in the

no
however, no segregation and / settling would take place

Example 4

Copolymerization was carried out in the manner described in Example 1 using 30 parts of glycidyl methacrylate, 20 parts of styrene, 10 parts of methyl methacrylate and 40 parts of ethyl acrylate as monomers. The Gopolymerisat were 3 ₉ 9 parts of ET-Methyläthanalamin and 8.0 parts of isopropyl alcohol _s added and the mixture left to the reaction as in Example 1 was ,, The resin solution contained 65 $ non-volatile component and had a viscosity of 73 poise at 25 ° 0. 42 parts of the above aqueous malonic acid solution and 30 parts of ethylene glycol monobutyl ether were added to 154 parts of this resin solution. After thorough mixing, 607 parts of deionized water were gradually added to the solution for dilution ₉ a semitransparent, stable dispersion containing the 12% nonheatable component was obtained .

■. Example 5

A reaction wurde'auf the procedure described in Example 1 by adding 5 _S 4 parts of morpholine and 8 "4 parts Ä'thylenglykolmonobatyläther to the copolymer solution obtained in Example 4 performed ,, The resin solution contained 65 $ niofat-flüohtige component and had a viscosity of 68 poise at 25 ° 0 _o to 154 parts of this resin solution will be 'added 25 parts of a 10bigen aqueous formic acid, hash good mixing were 654 parts of deionized water was gradually added to the solution for dilution, to give a colorless transparent aqueous solution containing 12 $ non-volatile component was obtained "

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Example 6

4-0 parts ethylene glycol monobutyl ether and 2 parts of azobisisobutyronitrile were placed in the reactor described in Example 1 and "While the mixture heated" to 85 ⁰ G _s was maintained at this temperature, a mixture νοηΊ5 parts GIycidylmethacrylate 5 parts of 2-hydroxyethyl methacrylate, 20 parts of styrene , 20 parts of methyl methacrylate, 40 parts of butyl acrylate and 2 parts of azobisisobutyronitrile were added continuously over the course of 2 hours, whereupon the reaction was continued for a further 3 hours at the same temperature. A transparent copolymer solution was obtained added "the mixture was left to 4 hours, the reaction at 85 ° C" the resin solution contained 65 $ non-volatile component and had a viscosity von.120 poise _"9 to 154 parts were the resin solution at 25 ⁰ G 45 parts of an aqueous 10 Laughing good luck given propionic acid solution ischung were 801 parts gradually added entionisiertea water, whereby a colorless transparent solution contained 10 $ _s the non-volatile component obtained .wurde _{s 0}

Example 7

40 parts of rutile type titanium dioxide was in 667 parts the aqueous resin solution obtained according to Example 1 dispersed. The dispersion was diluted with 267 parts of deionized water, leaving a paint in the form a white aqueous dispersion was obtained «This paint was used as a bath for a cathodic electrolytic Deposition used «The electrodeposition was carried out for 2 minutes under a voltage of 120 V using a stainless steel sheet Steel as the anode and a steel sheet treated with iron phosphate as the cathode, with a resin film

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was deposited on the cathode, laughing rinsing with water, the deposited Piim was "baked for 30 minutes at 180 ⁰ C to give a smooth glossy film of thickness was obtained u of about 20 _o No staining or discoloration was determined by dissolution of the surface of the workpiece found «The film had the good properties listed in the table.

Comparative experiment 1

A white paint in the form of an aqueous dispersion was made from 137 parts of a commercially available cationic water-soluble resin A - (73 $ non-volatile component, solution in isopropyl alcohol, base number 0.54 milliequivalents / g, viscosity 27 poise at 30 ⁰ G), 40 Parts of rutile type titanium dioxide, 3.6 parts of acetic acid and 752.4 parts of deionized water. This paint was electrodeposited in the manner described in Example 7 onto an iron phosphate treated steel plate. The film formed was ^{baked at 180 °} C. for 30 minutes. The film had a thickness of about 20 μ _ο it was insufficiently hardened and

had the poor properties shown in Table 1.

Comparative experiment 2

A white paint in the form of an aqueous dispersion was made from 125 parts of a commercially available anionic water-soluble resin B (80 ^ non-volatile component, solution in ethylene glycol monobutyl ether, acid, number 1.2 milliequivalents / g, viscosity 95 poise at 30 ⁰ C), 40 parts of rutile titanium dioxide, 9.6 parts of triethylamine and 758.4 parts of deionized water were prepared.

This paint was on an anode under a Electrolytically deposited voltage of 150 V for 2 minutes, a steel plate treated with iron phosphate as Anode and an untreated steel plate used as cathode became. The electrolytically deposited

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blow was rinsed with water and burned in, he had a thickness of about 20 / U and those mentioned in Table 1 good properties, but it was colored by dissolving the surface of the workpiece «

Table 1

Example 7 Comparative ^
attempt 1 Comparative
attempt 2 Appearance of the ab
different film Well Well some
coloured © performance hardness 2H F. 2H Ball recess after
Erichsen, 7 mm objection
free Crack bil
manure and
Lift up objection
free Ball impact test "
500 g, 50 cm dtoo dt ο ο dto _e Salt spray test for
96 hours Bladder bil- blister bil
manure and manure and
Rust formation
on the ground
1 mm from the total
Nick ten upper
surface © Bladder bil
manure and
Rust formation
within
of 2 mm
from a ~
cut Example 8

The paint prepared according to Example 2 was in the form of the aqueous solution and was electrolytically deposited on a cathode at 80% for 1 minute. A carbon rod was used as the anode and a chrome-plated steel sheet as the cathode Burned in at 180 ⁰ C, where ■ an approx. 10 p. thick, transparent, smooth, colorless film was obtained "This film had the good properties listed in Table 2")

Comparative experiment 5 ·.

A clear paint in the form of an aqueous solution was prepared from 200 parts of sines commercial kationisohen water-soluble resin C (50 $ _s not neutralized "flüobtige Komponent® _B solution in isopropyl alcohol and with VJasser

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--14 -

Produced formic acid, viscosity of 9 poises at 25 ° C) and 800 parts of deionized water "This paint was electrodeposited in the manner described in Example 8" manner on a chrome plated steel sheet »The deposited film was 30 minutes at 180 ⁰ C branded The film had a Thickness of about 10u. It was transparent and smooth as in Example 8, but had poor hardness and corrosion resistance, as the test results in Table 2 show »

Comparative experiment 4

A transparent paint in the form of an aqueous solution was prepared from 125 parts of the same commercially available anionic water-soluble resin B as in Comparative Experiment 2, 9 »6 parts of triethylamine and 865» 4 parts of deionized water. This paint was electrodeposited at 80 V for 1 minute, with a chrome-plated steel sheet connected as the anode. The film formed was rinsed with water and then baked ^{at 180 ° C. for 30 minutes.} The paint film obtained had a thickness of about 10 yds. Due to the chromium contained in it, which had been leached out during the electrolytic deposition, it was colored green and cloudy and not clearly transparent.

Table 2 Example 8

Appearance of the film lead hardness

Well

2H

Boiling water dips ^ st, flaw-2 Hours' free CASS test (continuous, perfect for 96 hours) free cross-cut test 100/100

Comparative comparative example 3 example 4

Well

HB

Blistering in 30 minutes

Blistering in 24 hours

100/100

colored and cloudy

2H

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Example 9

The paint produced in the manner described in Example 4 "in the form of an aqueous dispersion was" at 100% for 3 minutes on a sheet made of pure aluminum (1S-1 / 2H) or a corrosion-resistant sheet made of an aluminum alloy (52 S) connected as a cathode which had been degreased with a solvent and then etched with an alkali, was electrodeposited. As the anode, a metal plate was switched off stainless steel * The film formed was rinsed with water and then baked 20 minutes at 170 ⁰ C, whereby a smooth, transparent, colorless coating thickness was obtained from about 2OyU "The film had a pencil hardness of 2H and remained flawless in the exams, e.g. .the CASS test for 72 hours, the immersion test in 1 # EaOH for 72 hours and the immersion test in 5% H ₂ SO. for 24 hours. .

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Claims (6)

Claims 1) Thermosetting paint in the form of an aqueous dispersion or solution, consisting of a water-soluble organic and / or inorganic acid, water and a resin material that has been produced by reacting a secondary amine with hydroxy groups that are present on the side of the main chain of a copolymer , which consists of 5 to 50% by weight of an ethylenically unsaturated monomer containing epoxy groups and 50 to 95% of one or more unsaturated vinyl or acrylic monomers which contain no epoxy groups and are copolymerizable with the ethylenically unsaturated monomers, wherein .the secondary amine is used in an amount of 0.1 to 1.0 equivalent of the epoxy groups contained in the copolymer _o 2) paint according to claim 1, characterized in that that the copolymer is an ethylenically unsaturated monomer containing epoxy groups, glycidyl acrylate or glycidyl methacrylate 3) paint according to claim 1 and 2, characterized in that that the copolymer contains a bisalkanolamine as secondary amine. 4) paint according to claim 1 to 3, characterized in that the copolymer 0.1 to 0.6 equivalent contains secondary amine per equivalent of epoxy groups. 5) paint according to claim 1, characterized in that that it contains as acid a mixture of an organic acid with an inorganic acid » 6) paint according to claim 1 to 5, characterized in that it is also miscible with water contains organic solvent. 309849/1124