DE2733188A1 - Aq. cationic coating compsn. prepn. - from amine-epoxy! adduct, partially blocked poly:isocyanate and polyamide forming films of excellent corrosion resistance - Google Patents

Abstract

Prepn. of a cationic electrophoretic coating compsn. comprises (a) mixing or reacting (i) reaction product of an epoxy-amine adduct (I) and a partially blocked polyisocyanate (II) in wt. ratio of 95-5 (I) to 5-95 (II) and (ii) reaction prod. of a polyamide (III) and (II) in wt. ratio of 95-5 (III) to 5-95 (II) and (b) dissolving or dispersing the resluting mixt. or reaction prod. in an aq. medium by neutralisation with an acid. (III) has >=1 basic amino gps. and (II) has is not >1 free NCO gp. Wt. ratio of reaction prod. (i):(ii) is 90:10 to 10:90. Coatings of excellent corrosion resistance, surface smoothness and impact resistance are formed on phosphate primed and uprimed steel sheets, Zn- and Sn plated steel sheets, Al and Cu (alloy) substrates.

Description

Process for the preparation of cationic electrophoretic coating compositions

The invention relates to a process for the production of cationic electrophoretic coating compositions.

Under the name "cationic electrophoretic ^ coating mass" is to be understood as an aqueous substance compound that is produced by Neutralizing a synthetic resin with an acid to make the synthetic resin water-soluble, and dissolving and dispersing the synthetic resin is prepared in water, and which is capable of electrophoretic formation of a film on an object which is known as Cathode is used during the coating process. Up to now, such a cationic electrophoretic coating was a substance compound known by mixing a reaction product of bisphenol-A-epichlorohydrin epoxy resin and a primary or secondary amine with an isocyanate compound having partially blocked isocyanate groups. With electrophoretic When applied, the coating is baked in to remove the isocyanate groups to block and cause a reaction between the epoxy resin and the isocyanate compound, thereby creating a cured film is obtained.

The coating film thus formed from the mass, despite its high corrosion resistance, has the disadvantages due to the epoxy resin lower surface smoothness and impact resistance and is therefore unsuitable as a primer for motor vehicles and the like. To overcome such disadvantages, it is known to use the epoxy resin with a fatty acid or the blocked isocyanate compound to modify a polyalkene alcohol.

However, such a method has a problem that the modification results in lower corrosion resistance leads.

It is now an object of the invention to provide a process for the preparation of cationic electrophoretic coating compositions, which can form films that have excellent corrosion resistance, surface smoothness and impact resistance.

The above and other objects of the invention will be apparent from the following description.

The invention provides a method for producing a cationic electrophoretic coating mass in the following stages:

(I) mixing or reaction

(1) a reaction product of an epoxy amine adduct (A) and of a partially blocked polyisocyanate (C) in a weight ratio of 95 to 5 of (A) to 5 to 95 of (C)

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and

(2) A reaction product of a polyamide (B) and a partial blocked polyisocyanate (C) in weight ratio from 95 to 5 of (B) to 5 to 9 5 of (C),

wherein the epoxyamine adduct (a) is a reaction product produced by reacting an epoxy resin with a basic amino compound with at least one basic amino group, the polyamide (B) has at least one basic amino group and the partially blocked polyisocyanate (C) is a polyisocyanate compound having at least one blocked isocyanate group in the Is a molecule and has an average of more than zero to not more than one free isocyanate group per molecule, and the weight ratio 9o to Io of the reaction product of (A) and (C) to to 9o of the reaction product of (B) and (C), and

(II) Dissolving or dispersing the resulting mixture or reaction product in an aqueous medium by neutralization with an acid.

The binders of this invention have better dispersibility in water than those of U.S. Patent Application No. 612.281. Furthermore, the coating films made from the compositions excellent properties according to the invention, esp. in terms of corrosion and alkali resistance.

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The epoxyamine adduct (A) to be used according to the invention is a reaction product obtained by reacting an epoxy resin with a basic amino compound with at least one basic Amino group is formed. The reaction product of epoxy resin and basic amino compound is not particularly limited to the reaction conditions under which it is produced, insofar than it is obtained by the reaction between them. Suitable as epoxy resin are those compounds that are composed of a Phenolic compound and epichlorohydrin having at least two epoxy groups per molecule and usually having a molecular weight from about 2oo to 4,000, preferably about 4oo to 2,000.

Specific examples of phenolic resins are epoxy resin made from bisphenol A and epichlorohydrin, epoxy resin made from hydrogenated bisphenol A and epichlorohydrin, epoxy resin made from bisphenol A and ß-methylepichlorohydrin, polyglycidyl ether of novolak resin, etc. In this invention, such a phenol epoxy resin is usable together with polyepoxy compounds such as Polyglycidyl ethers of ethylene glycol, propylene glycol, glycerine, Trimethylolpropane or the like. Polyhydroxy alcohols, polyglycidyl esters of adipic acid, phthalic acid, dimer acid or the like. Polycarboxylic acid, Polyepoxide obtained by epoxidizing aliphatic cyclic olefin or 1,2-polybutadiene, etc. The polyepoxide compounds can be used in an amount of up to about 50 weight percent for corrosion resistance not affected by phenolic resins.

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Examples of the basic amino compound to be treated with the epoxy resin are aliphatic or alicyclic amino compounds with a primary and / or secondary amino group. Preferred examples are monoamines, such as mono- or dialkylamine, mono- or dialkanolamines and polyamines such as polyalkylenepolyamines, etc. Useful monoamines are mono- or dialkylamines of about 1 up to 18 carbon atoms, such as propylamine, butylamine, diethylamine, Dipropylamine, etc. Examples of mono- or dialkanol monoamines are ethanolamine, propanolamine, diethanoiamine, dipropanolamine etc. Usable examples of other monoamines are piperidine, cyclohexylamine, pyrrolidine, morpholine, etc. Examples of polyalkylene polyamines are ethylenediamine, hexamethylenediamine, diethylenetriamine, Triethylenetetramine, tetraethylenepentamine, propylenediamine, dipropylenetriamine, butylenediamine. Examples of other polyamines are N-aminoethanolamine, diethylenediamine, diethylenaminopropylamine, Hydroxyäthlaminopropylamin, Hydroxyäthylaminopropylamin, Monomethy1aminopropylamin, Piperazine, N-methylpiperazine, N-aminoethylpiperazine, etc. Particularly preferable are water-soluble ones aliphatic monoamines such as diethylamine, diethanolamine, etc. in terms of reactivity with epoxy resin. According to the present Invention can use an aromatic amine in conjunction with the aliphatic or alicyclic amine in such a proportion be used that the reaction product of epoxy resin and basic Amine still remains dispersible in water when neutralized with acid. Examples of usable aromatic amines are aniline, N-methylaniline, toluidine, benzylamine, m-xyIylenediamine, m-phenylenediamine, 4,4'-diaminodiphenylmethane, etc. The use

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such aromatic amine leads to the effect of increased water and corrosion resistance of the coating film.

The reaction of epoxy resin with a basic amino compound, which is exothermic, is simply effected when the reagents are mixed together at room temperature. In order to carry out the reaction quickly, however, it is appropriate to open the reaction system a temperature of about 5o to 15o ° C, advantageously to about 7o to heat up to 13o C. The basic amino compound to be treated with the epoxy resin can contain at least such a proportion be used so that the resulting product can be made water-soluble on neutralization with an acid. But when a primary monoamine is used as the basic amino compound, preferably 0.5 to 1 mole out of the total mole of the amine serves as Equivalent of the epoxy group to prevent gelation. Further, when only one polyamine is used, it is desirable to use at least 3/4 moles of the amine per equivalent of the epoxy group Use to avoid gelling. In such a case it is often preferable to induce the reaction in the manner by an epoxy resin is added dropwise to an amine and then the non-reacting amine by vacuum distillation or extraction to withdraw. It is preferable to use solvents in which the epoxy resin and the amino compound are soluble and those with are miscible with water. Examples are isopropanol, sec-butanol, tert-butanol, ethylene glycol monoethyl ether, diethylene glycol monoethyl ether (Carbitol) and the like. Alcohols, ethyl acetate, butyl acetate, ethylene glycol monoethyl ether acetate, carbitol acetate and the like. Esters, methyl ethyl ketone, diisobutyl ketone, methyl isobutyl ketone, di acetone alcohol, -. Dlage ± onalkoholme thy lather (pentoxone) and

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Like. Ketones. If the solvent is used, the proportion is usually up to about 60 percent by weight, preferably about 10 to 40 percent by weight based on the total amount of the epoxy resin and the amino compound.

The polyamide (B) to be used according to the invention is a polyamide having at least one basic amino group. More specific examples are polyamide obtained by condensation of dicarboxylic acid and polyamine, polyamide obtained by reaction of polyamine with oligomer obtained by ring-opening polymerization of lactam such as ε, - caprolactam, polyester polyamide of alkanolamine and dicarboxylic acid, and so on. Useful dicarboxylic acids are those represented by the general formula
HOOC-R-COOH

in which R is a saturated or unsaturated aliphatic hydrocarbon group or aromatic hydrocarbon group designated with 1 to 34 carbon atoms. Suitable examples are phthalic acid, malonic acid, maleic acid, fumaric acid, succinic acid (Succinic acid), azelaic acid, adipic acid, sebacic acid, dodecyl succinic acid, dimer acid, etc. The polyamines are polyalkylene polyamines having a primary amino group at both ends of the main chain represented by the general formulas

NH ₂ or

R.

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where R., R.sup.1 and R.sup.4, aliphatic hydrocarbon groups with 2 or 6 carbon atoms, R. denotes hydrogen or an aliphatic hydrocarbon group with 1 to 3 carbon atoms and η denotes an integer from 1 to 6. Preferred examples are ethylene diamine, propylene diamine, butylene diamine, hexamethylene diamine, tetraethylene pentamine, pentaethylene hexamine, hexaethylene heptamine, heptaethylene octamine, dietethylene triamine, triethylenetetramine, bis (3-aminopropy1) -amino-amine, etc., which include ^{1,3-bis (3 1 -amino) -amino} having 2 to 6 carbon atoms such as ethanolamine, propanolamine, hydroxyethylaminopropylamine, etc. Since the polyamide (B) must have an amino group, there is a need to react the dicarboxylic acid with an excess of polyamine or alkanolamine. For example, one mole of dicarboxylic acid is treated with 0.8 to 2.0 moles of polyamine or with lo to 2.5 moles of alkanolamines, or 0.1 to 0.6 moles of polyamine, with one mole of an oligomer which is produced by the ring-opening polymerization of a Lactams is produced. Such a reaction is carried out at a temperature of 100 to 25o ° C. in a nitrogen atmosphere, or at a temperature of 70 to 200 ° C. under reduced pressure while the resulting water is withdrawn from the assembly.

In order to obtain organic solvent-soluble polyamides, f * which have low melting points and viscosities, it is proposed RJY part adhesive, at least in part a dimeric fatty acid, such as the ^ v dicarboxylic acid and diethylene triamine or the like. Polyalkylenpolyami-

** ne to be used as a polyamine. To use according to the invention-

^a de partially blocked polyisocyanate (C) is a polyisocyanate

compound with at least one blocked isocyanate group in the molecule and on average more than zero to not more than one]

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free isocyanate group per molecule. If the compound contains less than a blocked isocyanate group in the molecule, the resulting electrophoretic coating tends to be less curable on baking, while if the average number of free isocyanate groups per molecule is greater than 1, the im The course of contact between the partially blocked polyisocyanates Compound and the reaction product of epoxy resin and basic amino compound or polyamide with basic amino groups takes place and therefore objectionable.

The partially blocked polyisocyanate can be readily prepared by reacting a polyisocyanate compound having at least two isocyanate groups in the molecule with a blocking agent in an amount sufficient to produce more than zero to no more than one free isocyanate group per molecule on average contains. Since this reaction is highly exothermic, it is desirable to add the blocking agent dropwise to the polyisocyanate compound. Preferably the reaction at a low temperature of about 2o is performed to 80 ⁰ C. Examples of useful polyisocyanate compounds are those which contain at least two isocyanate groups in the molecule, such as m- or p-phenyl diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4- or 2,6-tolylene diisocyanate, m- or p-xylylene diisocyanate and the like. aromatic diisocyanate compounds, hexymethylene diisocyanate, dimer acid diisocyanate, isophorone diisocyanate and the like. Aliphatic or alicyclic diisocyanate compounds, adducts of such aromatic, aliphatic or alicyclic diisocyanate compounds and ethylene glycol, propylene glycol, glycerol, trimethyiol

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aromatic, aliphatic or alicyclic diisocyanates, etc. Preferred among these examples are aromatic polyisocyanates, such as tolylene diisocyanate, xylylene diisocyanate and adduct of tolylene diisocyanate or xylylene diisocyanate and polyol.

The agents to be used are volatile hydrogen compounds of low molecular weight, such as methanol, ethanol, propanol, butanol, hexanol, cyclohexanol, benzyl alcohol, ethylene glycol monoethyl ether, Ethylene glycol monobutyl ethers and the like. Aliphatic, alicyclic or aromatic monoalcohols, dimethyl or diethylaminoethanol and the like. tertiary hydroxyamines, acetoxime, Methyl ethyl ketone oxime and the like. Oximes, acetylacetone, acetoacetate, Malonate and the like active methylene compounds, phenol, t-caprolactam, etc. are preferable among these examples aliphatic monoalcohols.

The resin composition, the main ingredient of the coating composition of the invention can be prepared from the compounds (A), (B), (C) by mixing or treating (1) before the reaction product of the epoxy resin adduct (A) with the polyisocyanate (C) and (2) a reaction product of the polyamide (B) with the polyisocyanate (C) will. The amount of epoxy groups that should remain in adduct (A) for the aforementioned reaction is preferably so much that the adduct produced does not gel (becomes stiff) or has too high a viscosity, namely not more than 1 per molecule of the epoxy resin.

The reaction between the partially blocked polyisocyanate (C)

or

and the epoxy amine adduct (A) or the polyamide (B) must be so

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be carried out so that no dissociation of the blocked isocyanate groups occurs, so as to cause gelation (stiffening) avoid. The reaction temperature is 40 to 14o ° C., preferably 60 to 12o ° c. In order to protect the primary amino groups contained in the compound (A) and / or compound (B) and a sufficient amount of amino groups for solubilization (solubilization) of the product with an acid or for prevention to avoid gelling, it is advantageous to (A) and / or (B) with acetone, methyl ethyl ketone, diethyl ketone, methyl isobutyl ketone or the like. To treat ketones that contain a substituent (substitute) that is less steric tends to convert some of the primary amino groups in ketimine to protect against the above reaction. The ketimine-forming reaction is readily carried out by adding the reagents to a Temperature of at least loo ° C are heated while the occurring water is distilled off.

So that the reaction of (C) with (A) or (B) a gel-free Gives the reaction product of reduced viscosity, the reaction can be carried out using an inactive one against the isocyanate group Solvents, such as isopropylene alcohol, sec-butyl alcohol, tert-butyl alcohol, ethyl acetate, butyl acetate, cellosolve acetate, Carbitol acetate, diethylene glycol dimethyl ether, diisobutyl ketone, Methyl isobutyl ketone, pentoxone or the like.

The reaction of the compound (A) with the compound (C) is in the weight percentage ratio of 9 5 to 5 of (A) to 5 to 9 5 of (C), preferably carried out from 80 to 3o of (A) to 2o to 7o of (C).

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In the reaction of the compound (B) with the compound (C), is the (B) to (C) ratio in percent by weight 9 5 to 5 of (B) to 5 to 95 of (C), preferably 8o to 3o of (B) to 2o to 7o from (C). If the reaction product of (A) and (C) is mixed or treated with the reaction product of (B) and (C), this amounts to Ratio of the former to the latter in percent by weight 9o to Io to Io to 9o, preferably 7o to 3o to 3o to 7o. The mixing or the reaction is carried out at room temperature to 150.degree. C., preferably at 80.degree. to 130.degree. The (A) to (B) ratio in Weight percent in the resulting resin composition is Io to 9o from (A) to 9o to Io from (B), preferably from 3o to 7o from (A) to 7o up to 3o of (B) and the total ratio of (A) and (B) to (C) is 5o to 9o from the former to 5o to Io from the latter, preferably 6o to 85 from the former to 4o to 15 from the latter. When the ingredients are used in the above-mentioned areas, the resulting substances (compositions) result in coating films with improved properties in terms of corrosion resistance, Hardness, surface smoothness, crush strength and alkali resistance

The amine value of the resulting resin product is generally about 25 to 400, preferably 50 to 200. If the amine value remains within the above range, the coating composition exhibits good dispersibility in water or excellent throwing power, and the coating film obtained therefrom shows excellent corrosion resistance.

According to the invention, the amount and the type of isocyanate for connection with components (A) and (B) can be freely changed and thus result in electrophoretic coating compositions with different types

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Properties. Also, the ratio of the reaction product of (A) and (C) to the reaction product of (B) and (C) is as desired changeable. For example, if a high molecular weight compound can be listed as (A) and a low molecular weight compound is used as (B), the viscosity can be adjusted with greater ease by adding a larger amount of (C) treated with (B) and a lesser amount of (C) treated with (A). This gives a favorable influence on the electrophoretic Characteristics. Further, when (A) is a compound that cannot readily react with blocked isocyanate groups, and (B) is one that is amenable to a reaction with it during baking, it is possible to combine a larger amount of (C) with (A) and treating a minor amount of (A) with (B) to make the resin to achieve rapid baking curing.

The resin binder is then neutralized with an acid and is thereby rendered soluble or dispersible in water. The for Acid to be used for neutralization is formic acid, acetic acid, propionic acid, butyric acid, hydroxyacetic acid, lactic acid or the like. water-soluble organic acid, or hydrochloric acid, phosphoric acid or the like water-soluble inorganic acid. the Acid is used in such an amount that it is at least sufficient to make the binder soluble or in an aqueous medium To make dispersible and is not more than the equivalent of the amino groups contained in the binder. The watery mass that obtained by neutralizing with the acid and in an aqueous

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Medium is dissolved or dispersed, has a binder concentration from about 3 to 30 weight percent, preferably about 5 to 15 weight percent at a pH of from about 3 to 9, preferably from about 5 to 7.

The aqueous medium to be used according to the invention is water or a mixture of water and an organic solvent. At There is a large selection of suitable organic solvents that are miscible with water, such as ethanol, isopropanol, sec-butanol, ethylene glycol monoethyl ether, ethylene glycol monobutyl approx and the like. Alcohols, butyl acetate, ethylene glycol monoethyl ether acetate, carbitol, carbitol acetate and the like. Esters, methyl ethyl ketone, Diacetone alcohol and the like. Ketones. The solvent is usually used in an amount of up to 50 weight percent based on Water used.

The aqueous solution or dispersion of the electrophoretic coating composition according to the invention may contain a pigment, a surfactant, a curing catalyst and the like as desired. Useful Pigments include color pigments and extenders; examples of color pigments are various common ones, such as red iron oxide, titanium dioxide, carbon black, etc. Examples of extenders are clay, Mica, tallow, calcium carbonate and the like. common fillers. The surfactant can be used, although it is not always necessary since the mass is completely soluble or dispersible in water without the surfactant. Nonionic ones, for example, can be used Surfactants such as polyoxyethylene glycol or polyoxypropylene glycol and their derivatives. Can also be used as curing catalysts

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(Hardener) is a wide variety of such hardeners such as Acetate, naphthenate, oleate, chromate, phosphate and similar salts of bismuth, lead, tin, iron, cobalt, nickel, aluminum, zinc, Manganese, zirconium, and the like metals.

The coating composition according to the invention can also be one that can be connected to it neutral or cationic, water-soluble synthetic resin Contained in such an amount that it does not affect the corrosion resistance of the mass. Examples of neutral resins are water-soluble phenolic resin, water-soluble melamine resin, polyacrylamide, methylolated polyacrylamide, polyvinyl alcohol, polyvinyl acetate, Polyvinyl pyrrolidone and polyvinyl methyl ether. Examples of cationic Resins are dialkylaminoethyl methacrylate or dialkylaminopropyl methacrylate comprising copolymers, an additive product of glycidil methacrylate copolymer and secondary amines.

The aqueous solution or dispersion of the coating composition can be apply electrophoretically with perfect results using the usual electrophoretic coating agents. The object to be coated serves as the cathode and an ordinary carbon plate as the anode. The electrophoretic coating process can be carried out under normal conditions. For example, the coated article is usually used for curing at Temperature from 15o to 25o ° C, preferably from 17o to 21o ° C during Baked for 15 to 45 minutes. When the coating is baked, the blocked isocyanate groups in the resin release the blocking agent and initiate a crosslinking or crosslinking reaction with the amino, amido, hydroxyl and the like groups in the resin so as to effect the curing.

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The electrophoretic coating composition according to the invention is proper for coating usually treated with zinc phosphate and iron phosphate and also untreated, more prone to corrosion Steel sheets. The sheets provided with the coating show, although they do not contain any hexavalent chromium compound, a high level Corrosion resistance. This is an excellent feature of the invention over the conventional electrophoretic coating compositions is not achieved. The coating compound according to the invention is also suitable for coating galvanized and tinned Sheet steel as well as aluminum, copper and copper alloy substrates.

The invention is described in detail below by way of Examples, in which parts and percentages are in parts by weight and Weight percent are expressed. The amine values in the examples are determined using the following method:

Determination of the amine value:

A sample of 0.2 to 0.3 g is placed in a 100 ml Erlenmeyer flask given and melted while heating. After cooling, the sample is titrated with an aqueous 1 / 10N HCl solution with bromophenol blue as an indicator. The amount of titrant is measured if the color changed from blue to yellow, in order to then calculate the amine value from the following equation:

Amount of the 1 / loN factor of the amine value = HCl solution (ml) x 1 / loN HCl solution _{χ 5 61}

Sample amount (g) x solid _{content χ _1_}

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The properties of the films obtained according to the examples are measured according to the following method:

(l) Pencil hardness:

Leave a test plate (sheet metal) in a chamber with constant Temperature and constant humidity at a temperature of 2o + 1 C and a humidity of 75% stand for one hour. A pencil (trademark "UNI", product of Mitsubishi Pencil Co., Ltd., Japan) is to be sharpened with a pencil sharpener and then to remove the sharp point of the pencil flat. Then press the pencil against the coated surface of the sample board at an angle of 45 ° between the pencil axis and the coating surface and push the pencil in the assumed position at a constant speed of 3 cm / sec. forward. Repeat the same procedure five times with each of the pencils of different hardness. The hardness of the coating is expressed due to the highest hardness of the pencils with which the coating is after remains unbroken for more than four lines.

(2) Shock resistance:

After the coated panel in a constant temperature chamber and humidity has stood at a temperature of 2o + 1 ° C and a humidity of 75% for 1 hour, becomes the following Rehearsal carried out in the same room.

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A support and a joint of 1/2 "diameter are attached in a Du Pont impact testing machine and the panel is also attached overlaying the coating area between them. The weight (lkg) is dropped onto the joint from the prescribed height and the plate is removed. After remaining in the room the surface damage is checked for one hour.

(3) Corrosion Resistance:

Diagonal cut lines are ^ in the film on the test plate in such Extent formed that the base plate is reached. The test panel is then sprayed with brine using a 5% solution aqueous solution of common salt at a temperature of 35 C and a humidity of 100%.

(4) Surface smoothness:

Determined with the naked eye.

(5) Erichsen value (installation test):

The coated plate is placed in a constant temperature room and humidity held at 20 ° C and 75% humidity for one hour. The plate is then put into an Erichsen testing machine used.

A punch with a radius of Io mm is in contact with the back of the plate on a given stretch of the path with the most uniform possible speed of about 0.1 mm / sec. outward

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pressed. The bulged portion of the plate is visible to the naked eye for cracking or peeling immediately after bulging investigated in order to determine the greatest stroke distance of the punch that does not cause any change in the coating.

(6) Alkali resistance:

The coated plate is immersed in a caustic soda solution at a concentration of 5 percent by weight immersed at 2oC. The plate is removed after the prescribed period and carefully rinsed with water. After leaving it for one hour at room temperature, the surface damage is checked.

example 1

A quantity of 95o parts of an epoxy resin of the bisphenol A type with an epoxy equivalent of 95o (trade mark "Epikote Ioo4", Product of Shell Chemical Co., Ltd., Japan) is dissolved in 200 parts of butyl acetate and the solution is added dropwise to a mixture from 6o Tlen. Ethylenediamine and loo Tlen. Butyl acetate added at a temperature of up to 6o C. After the evolution of heat has ceased, the reaction mixture is at for two hours Held 80 ° C and then distilled under reduced pressure to remove the solvent and the unreacted diamine, wherein an epoxy resin-amine adduct with an amine value of llo is formed. The adduct is heated with 12o Tlen. Methyl ethyl ketone and 5o Tlen. Treated toluene and the vapor in the compressor liquefied again, thereby the responsible amino group in ketimine to transform. The product is 38o TIe. Pentoxon added.

8 O 9 ft 6 5 / O

81.4 parts of n-butanol are separated therefrom, 174 parts dropwise. Tolylene diisocyanate (a mixture of 80%, 2,4-tolylene diisocyanate and 2o% 2,6-tolylene diisocyanate) at a temperature of up to 5o C added over a period of 2 hours and the reaction mixture is then at a temperature of 60 ° C for one hour long held to 255 TIe. a partially blocked diisocyanate with a molar ratio of 1: 1.1 (tolylene diisocyanate: n-butanol) to obtain. The partially blocked diisocyanate (255 TIe.) Is added to the above mixture and the resulting mixture is at Treated 70 ° C for two hours, with a blocked polyisocyanate containing amine adduct epoxy resin with an amine value of 69 results.

Adipic acid (146 TIe) and 124 TIe. Diethylenetriamine are in a Heated nitrogen gas atmosphere with stirring to remove water. The mixture is then held at 190 to 200 ° C. for 3 hours and then cooled to 23o TIe. a polyamide resin with an amine value of 56o.

This resin (23o TIe), 7o TIe. Methyl ethyl ketone and 15 TIe. toluene are re-liquefied with heating and caused to react until no more water flows off, around the terminal amino group to turn into ketimine.

A lot of 'XVi Tlen. (Solids) of polyisocyanate (trade mark "Desmodur 1", product of BAYER AG, West Germany) of one mole of trimethylolpropane and 3 moles of tolylene diisocyanate wid dropwise 6o parts of cellosolve (ethyl glycol) at a temperature of up added to 5o ° C and the mixture two held for hours at 7o ° c to 279 tie. (Solids) one part

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to obtain blocked polyisocyanate. That partially blocked Polyisocyanate (279 TIe. Solids) is added dropwise to the ketimine-containing Product added at 50 to 60 ° C, the mixture held at 70 ° C for two hours and then cooled, with a blocked Isocyanate-containing polyamide resin with an amine value of 14o is produced. This resin is the blocked isocyanate containing Amine adduct epoxy resin added to give a resin composition with about 63% solids and an amine value of 93. 16o Tlen. the mass will be 6.5 TIe. Lactic acid and "U2.5 TIe. Deionized Water added to make an aqueous dispersion with about 40% particulate matter to obtain. Titanium dioxide (2o TIe.), 9 Tie. Ton and 3 TIe. Iteisilicate are added to the dispersion, the mixture is kneaded in a ball mill for 20 hours and diluted with deionized water to form an electrophoretic coating bath with 13% non-volatile components and a pH of 6.0. Degreased steel plates are electrophoresed Coated at 28oV for 3 minutes using the bath and baked at 180oC for 30 minutes. The coating film has a thickness of 18 µ, a pencil hardness of 3H, and the following properties.

Impact resistance (1/2 ", 1 kg., 50 cm) no change

Corrosion resistance no change ir

24o hours

Surface smoothness excellent

Erichsen value at least 7 mm.

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EXAMPLE 2

A quantity of 500 tlen. an epoxy resin of the bisphenol A type with an epoxy equivalent of about 500 (trademark "Araldite 7o72?" Product of the company CIBA-GEIGY A.G., Switzerland) is sold in 25o Tlen. Butyl acetate dissolved with warming and 6 3 TIe. Diethanolamine are added to the solution. The mixture is reacted for 2 hours. A lot of 276 tsp. of an adduct (molar ratio 1: 1) made from 174 parts. Tolylene diisocyanate (the same mixture as used in Example 1) and Io2 Tlen. n-hexanol are added to the reaction mixture. The resulting mixture is treated at 70 ° C. for 2 hours. Be separated from it a mixture of 187 parts. Dimer acid (trademark "Versadyme 216" product of DAIICHI GENERAL CO., Ltd. Japan), 55 TIe. Isophthalic acid and 10 3 parts of diethylenetriamine heated with stirring and treated at 22o C for two hours with removal of the distilled water. The reaction mixture is then heated to 120.degree cooled at reduced pressure. The cooled mixture is then 25o TIe. Methyl isobutyl ketone added and the resulting The mixture is liquefied back for the reaction, distilled and recompressed (for about 10 hours) until there is no more water is distilled off, and then cooled to 6o ° C. The reaction mixture will be 133 Tie. of the 1: 1 adduct of tolylene diisocyanate and -n-hexanol was added and the mixture was then treated for two hours. The reaction mixture obtained becomes the above Reaction product of epoxy resin added and the mixture treated with stirring and heating to 8o ° C for one hour, wherein

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a resin composition with 74% solids and an amine value of 65 is created. With 135 tsp. this mass becomes 4.2 parts of glacial acetic acid and 139 deionized water mixed to obtain a 36% neutralized aqueous dispersion. Titanium dioxide (2o part.) , 9 tIe. Ton and 3 TIe. Lead silicate are added to the dispersion and the mixture is in a ball mill for 20 hours kneaded and diluted with deionized water to give an electrophoretic Form a coating bath with 13% solid particles and a pH of 5.4. Steel panels treated with iron phosphate are electrophoretically using at 19oV for 3 minutes of the bath and baked at 170 ° C for 25 minutes. The coating film has a thickness of 26 µ, a pencil hardness of 2 H and the following properties:

Impact resistance (1/2 ", 1 kg, 50 cm) no change

Corrosion resistance no change

in 76o hours

Surface smoothness excellent

Erichsen value at least 7 mm

Resistance to alkali (5% NaOH, 2o ° C) no change

in looo hours.

Example 3

A mixture of 400 parts. an epoxy resin of the bisphenol A type

809885/0430 _ ₂₈ _

with an epoxy equivalent of about 2oo and 2oo TIe. Cellosolve acetate is heated to 60 ⁰ C. A mixture of 61 parts. Monoethanolamine and 32 parts. Diethylamine is added to the heated mixture. The resulting mixture is treated at 70 ° C. for three hours. The reaction product are 258 TIe. an adduct of 1 mole of xylylene diisocyanate and one mole of n-butanol was added. The mixture is treated at 70 ° C. for two hours to obtain a blocked isocyanate with amine adduct-epoxy resin. Separately from this, 4oo TIe. a dimer acid type polyamine resin (trademark: "Vesamid lo", product of DAIICHI GENERAL Co., Ltd. Japan) in 200 parts. Diethyl ketone is mixed and the mixture is liquefied back with heating (distilled in reflux) until no more water is distilled off. The then cooled to 80 ⁰ C the reaction mixture are 128 TIe. (Solid content) of an adduct of 2 moles of Cellosolve and one mole of an addition product (trade mark "Takenate D-lo2", addition product of 3 moles of tolylene diisocyanate and one mole of trimethylolethane, manufactured by Takeda Chemical Industry Co., Ltd., Japan) was added. The mixture is treated for 2 hours. The resulting reaction mixture is mixed with the blocked isocyanate-containing epoxy resin with amine adduct. The mixture is treated at 100 ° C. for one hour to produce a resin mixture having 78% particulate matter and an amine value of 81. 128 parts of the mass are 7.8 TIe. 70% strength hydroxyacetic acid and 152 parts of deionized water mixed in to obtain a 36% strength, neutralized aqueous dispersion.

8 O 9 8 8 5/0 - * <8-0

-W-

The dispersion will be 18 TIe. red iron oxide, 12 teas. Talk and 1 part of lead oleate is added and the mixture is kneaded in a ball mill for 20 hours and then with deionized water diluted to obtain an electrophoretic coating bath with 15% solids and a pH of 5.9. Defatted Sheet metal panels are electrophoretically coated at 16oV for two minutes using the bath and at 19oC Baked for 15 minutes. The coating film has a thickness of 21 µ, a pencil hardness H and the following properties:

Surface smoothness excellent

Impact resistance (Du Pont impact test

werk, 1/2 ", 1 kg, 5ocm) .. no change

Erichsen value at least 7 mm

Corrosion resistance no change in

48o hours

Alkali resistance (5% NaOH, 2o ° C) no change in

76o hours.

COMPARATIVE EXAMPLE 1

A quantity of 500 tlen. Epoxy resin (trademark "Epikote lool". Product of Shell-Chemical Co., Ltd., Japan) with epoxy equivalent 500 is in 3oo Tlen. Dissolved methyl isobutyl ketone and 7 3 parts Diethylamine is added dropwise to the solution at 80 to 100 ° C. The mixture is heated to 12o ° C and on the same Maintained temperature for 1 hour. Then 174 TIe. Tolylene diisocyanate drop by drop I8o Tlen. Ethylene glycol monoethyl ether

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-3o-

added at 60 to 80 ° C., the mixture is heated to 120 ° C. and kept at the same temperature for 1 hour. The reaction mixture is mixed with the epoxy-amine reaction product obtained above to form a resin composition having about 74% solids to obtain. 135 tlen. the crowd will be 5 tie. Acetic acid and 860 TIe. Deionized water is added to make an aqueous dispersion with a solids content of lo% and a pH of 4.ο. It was found that the dispersion contained some water-insoluble components in the suspension. The dispersion is used as a coating bath for the electrophoretic coating of a degreased steel sheet at 25 ° C and 19oV for 2 min. used. The coated sheet is baked at 180 C for 30 minutes, to obtain a 12 µ thick, hard film with a pencil hardness of 5H. The film has poor surface smoothness and defects such as pinholes and blistering (peeling). The film swells with acetone and tears when a prescribed weight (1/2 "and 1 kg) is dropped on it from a height of 20 cm. However, if it is for corrosion resistance is checked, the film remains free of any changes for 24o hours.

COMPARATIVE EXAMPLE 2

A quantity of 500 tlen. Epoxy resin of the bisphenol A type (Epikote loo1) with epoxy equivalent 500 is in 2oo parts. toluene dissolved and 73 TIe. Diethylamine are added dropwise to the solution

ugeset. The Gei

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added at 80 to 100 ° C. The mixture is then brought to 12o C

-31-

heated and kept at the same temperature for 1 hour. The reaction mixture are also 28o TIe. dehydrated castor oil fatty acid added and the resulting mixture is heated first to llo ° C and progressively to 2oo ° C, while excess Toluene is withdrawn. The mixture is treated at the same temperature for 5 hours in reflux to a To effect reaction until the acid value thereof is reduced to 5 or less while the resulting water is distilled off will. After the reaction has ended, the reaction mixture is distilled under reduced pressure, 300 TIe. Butyl acetate are the The residue is added and the mixture is cooled to 100.degree. The cooled mixture is 248 TIe. of a reaction product of tolylene diisocyanate and n-butanol (in a 1: 1 molar ratio) added separately, the mixture is heated to 12oC and held at the same temperature for two hours, whereupon a resin composition with about 79% solids results. Of the The mass (127 parts) will be 5.6 parts. Acetic acid and 127 TIe. deionized Water added to produce an aqueous dispersion with 40% solids. The dispersion is very cloudy white. In the same way as in Example 2, the dispersion becomes a pigment-containing mass with 13% non-volatile constituents and reformulated to a pH value of 3.8. The mass is used as a coating bath for the electrophoretic coating of a degreased steel sheet used at 30 ° C and I3o V for 3 minutes. The coated sheet is then baked at 180 ° C. for 30 minutes to get one 28 u thick film with a pencil hardness of H. At 13o V for 3 minutes, the bath has a throwing power (depth effect) from 8.ο cm. When testing for impact resistance with a prescribed weight q U./2, "., L.kfl,) at 50 cm, the

-32-

Film unchanged, while the salt spray sample marked blistering on the cross-sectional parts of the film in 72 hours.

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Claims (20)

PATENT ADVERTISEMENT My sign K4o3-2o-ku Please repeat in the answer »" Sign your message from 899 Lindau (Bodensee) Rennerle 10 PO Box 3160 2o. July 1977 Serves Kansai Paint Company, Limited, 365, Kanzaki, Amagasaki-shi, Hyogo-ken, JAPAN claims 1. Process for the preparation of a cationic electrophoretic Coating compound, characterized by the process stages (I) mixing or reaction (1) a reaction product of an epoxyamine adduct (A) and of a partially blocked polyisocyanate (C) in a weight ratio of 9 5 to 5 of (A) to 5 to 95 of (C) S ^and oo (2) a reaction product of a polyamide (B) and a ^ - partially blocked polyisocyanate (C) in weight ratio ^ ratio of 95 to 5 of (B) to 5 to 95 of (C), wherein the epoxyamine adduct (A) produces a reaction product Telephone Telegraph Office hours: Bank accounts: ~ 2 ~ Postal checking account: Lindau (0 83 82) 6917 054374 by arrangement Bayer Vereinsbank Lindau (B) No. 120 8578 (BLZ 735 200 74) Munich 295 25-809 Hypo-Bank Lindau (B) No. 6670-278 920 (BLZ 735 206 42) Vofcsbank Lindau (B) No. 51720000 (BLZ 735 90120) INSPECTED by reacting an epoxy resin with a basic amino compound with at least one basic amino group, the polyamide (B) has at least one basic amino group and the partially blocked polyisocyanate (C) is a polyisocyanate compound having at least one blocked isocyanate group in the Molecule and has an average of more than zero to no more than one free isocyanate group per molecule, and that Weight ratio is 9o to Io of the reaction product of (A) and (C) to Io to 9o of the reaction product of (B) and (C), and (II) Dissolving or dispersing the resulting mixture or reaction product in an aqueous medium by neutralization with an acid. 2. The method according to claim 1, characterized in that the epoxy resin has a molecular weight of owns about 2oo to 4,000. 3. The method according to claim 2, characterized in that the molecular weight is in the range of about 4oo to 2,000. 4. The method according to claim 1, characterized in that the epoxy resin consists of bisphenol A and epichlorohydrin is obtained. 6,9885 / 000 5. The method according to claim 1, characterized that the basic amino compound is an aliphatic or aliphatic-cyclic amino compound with a primary and / or secondary amino group. 6. The method according to claim 5, characterized in that the basic amino compound is a water-soluble is aliphatic monoamine. 7. The method according to claim 1, characterized in that the epoxy resin with a basic amino compound is reacted at a temperature of about 5o to 15o ° C. 8. The method according to claim 1, characterized in that the polyamide is a product by Condensation of a dicarboxylic acid and polyamine is produced, a product of the reaction of a polyamine with an oligomer originated from the ring-opening polymerization of a lactam, or a polyester polyamide of an alkanolamine and a dicarboxylic acid represents. 9. The method according to claim 1, characterized in that the partially blocked polyisocyanate compound an aromatic polyisocyanate having at least one blocked isocyanate group in the molecule and an average represents from more than zero to no more than one free isocyanate group per molecule. e0988B / -4- 10. The method according to claim 9, characterized that the aromatic polyisocyanate is tolylene diisocyanate, xylylene diisocyanate or an adduct of tolylene diisocyanate or xylene diisocyanate and a polyol. 11. The method according to claim 1, characterized that the reaction product of (A) and (C) is obtained by reacting 80 to 3o of (A) with 2o to 7o of (C) in a weight ratio. 12. The method according to claim 1, characterized in that it is marked that the reaction product of (B) and (C) is obtained by reacting 8o to 3o of (B) with 2o to 7o of (C) in a weight ratio. 13. The method according to claim 1, characterized that the reaction product of (A) and (C) with the reaction product of (B) and (C) in such a quantitative ratio mixed or treated so that the weight ratio of 9o to Io of the former reaction product to Io to 9o of the latter Reaction product is. 14. The method according to claim 1, characterized that the acid used for neutralization is a water-soluble organic or inorganic acid. -5- 809885/0430 15. The method according to claim 1, characterized that the synthetic resin binder has an amine value of about 25 to 400. 16. The method according to claim 15, characterized that the amine value is in the range of 5o to 2oo. 17th Method according to claim 1, characterized that it has a binder in a concentration of about 3 to 3o percent by weight. 18. The method according to claim 1, characterized that the pH is about 3 to 9. 19. The method according to claim 1, characterized that it also contains a neutral or cationic water-soluble resin. 20. Cationic electrophoretic coating composition, characterized by the production in The method of claim 1. -6- 809885/000