Coating resin composition

Abstract: A coating resin composition composed mainly of an epoxy resin derivative obtained by reacting an amine compound containing hydroxyl groups, secondary amino groups and amide groups in a molecule with an epoxy resin in its epoxy groups. The resin composition can be used alone, or in the combination with an epoxy resin containing, per molecule, on the average at least 2 epoxy functional groups each comprising an epoxy groups directly bound to an alicyclic ring and/or bridged alicyclic ring, and is useful in a cationically electrodepositable paint.

Description: This invention relates to a novel resin composition for a paint, and more specifically to a resin composition having improved smoothness of a coated surface, bath stability and water dispersibility, and useful in a cationically electrodepositable paint. Further, this invention relates to a resin composition for a cationically electrodepositable paint which is, when conjointly used with a curing agent, excellent in water dispersibility, stability and curability as well as in smootheness, adhesion, weatherability and low-temperature curability of a coated film. Heretofore, as a resin for a cationically electrodepositable paint, (i) a polyamine resin such as an amine-added epoxide resin, e.g. an adduct of a polyepoxide and a secondary amine such as diethanolamine or ethylethanolamine has been used in most cases. This is crosslink-cured by an ester exchange reaction and/or an amide exchange reaction and/or an urethane exchange reaction and/or an urea exchange reaction and/or an etherification reaction with a terminal double bond to form an electrodeposition coated film. However, smoothness of a coated surface is not enough; in order to improve this, it has been required to lower a molecular weight of the adduct or to introduce a soft component that gives an effect of plasticity. Nevertheless, when the molecular weight of the adduct is lowered, dispersion stability in water is decreased. When an external plastic component (e.g. a polyether polyol) is mixed to introduce the soft component, water dispersibility of the adduct is decreased. Meanwhile, when a polyfunctional soft component (e.g. sorbitol polyglycidyl ether) is chemically bound, the water dispersion is itself highly viscous, making it hard to smooth the coated surface. Even if a difunctional soft component (e.g. polypropylene glycol diglycidyl ether) is chemically bound, water dispersibility is decreased. Moreover, (ii) an adduct of a polyepoxide and a secondary mono- or poly-amine containing a ketiminated primary amino group is known as a resin for a cationically electrodepositable paint (see, for example, US-A-4,017,438). Said adduct is good in water dispersibility, but not enough in smoothness of a coated surface. A blocked polyisocyanate compound is widely used as a curing agent of these resins for the cationically electrodepositable paint, but suffers varied problems, and it has been strongly demanded to eliminate same. Namely, regarding the adduct (i), it is difficult to meet both the water dispersibility and the corrosion resistance at the same time. Meanwhile, regarding the adduct (ii), especially when using a blocked polyisocyanate compound (curing agent) containing a blocked isocyanate functional group having low-temperature dissociation property and/or a blocked isocyanate functional group containing an active double bond (e.g. an isocyanate blocked with hydroxyethyl acrylate), storage (or bath) stability is poor because an active hydrogencontaining cationic group is present in the adduct (ii), and besides water dispersibility is not enough. In addition, a resin composition for a cationically electrodepositable paint has serious substantial drawbacks that a temperature at which to start curing is high (usually above 170°C); when an organotin compound is used as a curing catalyst to lower the temperature at which to start curing, said compound poisons an exhaust gas combustion catalyst of a baking furnace; and when heating is conducted at a high temperature to cure a coated film, the blocked isocyanate is heat decomposed so that gum and soot are generated, and a top coat film causes yellowing, bleeding and impediment of curing, notably decreases weatherability and tends to whiten. It has been long demanded to remedy these drawbacks as well. The present inventors proposed beforehand a resin composition for a cationically electrodepositable paint by using a certain specific polyfunctional polymer as a curing agent, said resin composition being excellent in bath stability and curability without decreasing corrosion resistance, being able to remedy the aforesaid various drawbacks given by the organotin compound and the blocked polyisocyanate compound, having excellent adhesion because strain owing to volume shrinkage does not occur, remarkably improving weatherability of a coated film and being excellent in low-temperature curability (see post-published EP-A-0 356 970). However, when said resin composition was subjected to a salt dip test at 50°C of a film coated on an untreated steel plate, decrease in dispersibility of a cationic group was observed and there was a fear that dispersibility of an emulsion might be decreased. Resins for an electrodepositable paint utilizing self crosslink-curability by a ring opening reaction between epoxy groups without the use of a curing agent have been hitherto known as proposed in e.g. GB-A-1,306,101-2, 1,327,071 and US-A-3,686,202. However, said resins cannot give bath stability of an electrodepositable paint and curability of a coated film at the same time. For example, among these resins, the most common glycidyl ether-type polyepoxy compound is excellent in curability but poor in bath stability. EP-A-0 301 433 relates to a coating resin composition comprising, as a coating-forming resin binder, an epoxy resin derivative containing a functional group represented by the following formula wherein R 1 represents a hydrogen atom or methyl group; each of R 2 and R 3 represents C 1 -C 5 alkyl group independently of other; R 4 represents a C 2 -C 6 alkylene group in which an ether group (-O-) may be present in the carbon chain; and n represents an integer from 1 to 6. This coating resin composition is useful for cathodic electrodeposition coating. This invention relates to a resin composition for a cationically electrodepositable paint that remedies the drawbacks of the resins for the cationically electrodepositable paint [for example, the adducts (1) and (ii)] and even when conjointly used with the various curing agents, does not give the aforesaid drawbacks. Under the aforesaid circumstances, the present inventors have made extensive studies to provide a coating resin composition excellent in smoothness of a coated surface, storage (or bath) stability and water dispersibility and to be used in a cationically electrodepositable paint without the decrease in corrosion resistance, and consequently discovered that the above object can be achieved upon using as a film-forming resin an epoxy resin derivative obtained by reacting an amine compound containing hydroxyl groups, secondary amino groups and amide groups in a molecule with epoxy groups of an epoxy resin. They have further discovered that by using the above epoxy resin derivative in combination with a specific polyfunctional polymer, there can be obtained, without decreasing corrosion resistance of a coated film, a film-forming resin composition for a cationically electrodepositable paint, which composition is excellent in water dispersiblity, bath stability and curability, can eliminate the aforesaid various drawbacks given by the use of the organotin compound and the blocked polyisocyanate compound, is excellent in adhesion because strain by volume shrinkage does not occur, remarkably improves weatherability of a coated film, has excellent low-temperature curability, can pass an untreated salt dip test and has excellent smoothness of a coated surface. Thus, there is provided a coating resin composition composed mainly of an epoxy resin derivative obtained by reacting an amine compound containing hydroxyl groups, secondary amino groups and amide groups in a molecule with an epoxy resin in its epoxy group. An electrodeposition coated film formed with the resin composition for the cationically electrodepositable paint in this invention is cured at a temeprature of about 250°C or lower. Especially when a compound containing a metal such as lead, zirconium, cobalt, aluminum, manganese, copper, zinc, iron, chromium or nickel is blended as a catalyst either singly or in combination, it can be cured even by heating at a low temperature of about 70 to about 160°C. Accordingly, the resin composition for the cationically electrodepositable paint in this invention possesses advantages that said composition can be cured at a low temperature of 160°C or less without the use of a tin catalyst; as the blocked isocyanate compound or its derivatives may not be used, the aforesaid various drawbacks provided by using same can be eliminated; because volume shrinkage owing to heat decomposition does not occur, good adhesion is exhibited; since an aromatic urethane bond or an aroamtic urea bond is not introduced into crosslink, weatherability is little impaired; corrosion resistance and curability of the electrodeposition coated film are excellent; electrodeposition bath stability is good; because an amine compound, especially a compound of formula (I) to be described later is used as a cationizing agent, emulsion stability is good; smoothness of a coated surface is good; and excellent corrosion resistance is also shown in a salt dip test at 50°C of a film coated on an untreated plate. The resin composition provided by this invention will be described in more detail below. (A) Epoxy resin derivative The epoxy resin derivative which is a main component of the coating resin composition in this invention is obtained, for example, by reacting an amine compound (A-1) containing hydroxyl groups, secondary amino groups and amide groups in a molecule with an epoxy resin (A-2) in its epoxy groups. The amine compound (A-1) is a compound containing hydroxyl groups, preferably primary hydroxyl groups, secondary amino groups and amide groups in a molecule at the same time. Specifically, it is a compound represented by formula (I), wherein n is an integer of 1 to 6, preferably 1 to 3, R 1 denotes a hydrogen atom, a methyl group or an ethyl group, and R 2 denotes a hydrocarbon group containing 8 to 36, preferably 12 to 20 carbon atoms which group may contain a hydroxyl group and/or a polymerizable unsaturated group. In formula (I), the hydrocarbon group indicated at R 2 includes a linear aliphatic hydrocarbon group, a branched aliphatic hydrocarbon group and an aliphatic hydrocarbon group that may optionally contain an alicyclic ring in a chain. Said aliphatic hydrocarbon group may optionally contain at least 1, preferably 1 to 3 hydroxyl groups as a substituent and/or at least 1, preferably 1 to 3 polymerizable double bonds in a chain. Such hydrocarbon group is a residue of an organic monocarboxylic acid of formula R 2 -COOH (III) in a reaction scheme A to be shown later. Concrete examples of the monocarboxylic acid include caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, ricinoleic acid, linoleic acid, linolenic acid, eleostearic acid, 12-hydroxystearic acid and behenic acid. Of these, stearic acid, oleic acid, linoleic acid and 12-hydroxystearic acid are especially preferable. The amine compound of formula (I) can be produced, as shown in the following reaction scheme A, by adding an organic monocarboxylic acid (III) containing 9 to 37 carbon atoms to a N-hydroxyalkylalkylenediamine compound (II) at an approximately equimolar ratio. wherein R 1 , R 2 and n are as defined above. Desirable examples of the diamine compound (II) used in this reaction include hydroxyethylaminoethylamine, N-hydroxyethylpropylenediamine, N-hydroxyethylbutylenediamine, N-hydroxyethylpentylenediamine, N-hydroxyethylhexylenediamine, N-(2-hydroxy)propylethylenediamine, N-(2-hydroxy)propylpropylenediamine, N-(2-hydroxy)propylbutylenediamine, N-(2-hydroxy)propylpentylenediamine, and N-(2-hydroxy)propylhexylenediamine. Among them, hydroxyethylaminoethylamine and N-hydroxyethylpropylenediamine are preferable. Examples of the monocarboxylic acid (III) include mixed fatty acids such as a coconut oil fatty acid, a castor oil fatty acid, a rice bran oil fatty acid, a soybean oil fatty acid, a tall oil fatty acid, a dehydrated castor oil fatty acid, a safflower oil fatty acid, a linseed oil fatty acid, and a tung oil fatty acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, ricinoleic acid, linoleic acid, linolenic acid, eleostearic acid, 12-hydroxystearic acid, and behenic acid. Of these, the tall oil fatty acid, stearic acid, oleic acid, linoleic acid and 12-hydroxystearic acid are especially preferable. The equimolar adduct of the N-hydroxyalkylalkylenediamine (II) and the monocarboxylic acid (III) is formed by mixing both the components at a nearly equimolar ratio, removing a prescribed amount of a reaction water using an organic solvent such as toluene or methyl isobutyl ketone and removing the remaining organic solvent by a reduced pressure method. The content of the hydroxyl groups in the amine compound (A-1) is usually 44 to 350, preferably 60 to 230, more preferably 100 to 200, calculated as a hydroxyl value. The content of the secondary amino groups is usually 88 to 350, preferably 120 to 230, more preferably 120 to 200, calculated as an amine value. A solidification point (according to a differential scanning calorimetry) is usually 100°C or lower, preferably 85°C or lower. The content of the amide groups is usually approximately the same (mols) as the content of the secondary amino groups. As the epoxy resin (A-2) reacting with the amine compound (A-1), a polyepoxide compound containing on the average at least 2, preferably 2 to 30, more preferably 2 to 15 1,2-epoxy groups and having a number average molecular weight of at least 200, preferably 400 to 4,000 and more preferably 800 to 2,000, is suitable. As the polyepoxide compound, compounds known per se are available. For example, a polyphenol polyglycidyl ether resulting from reaction of a polyphenol and epichlorohydrin in the presence of an alkali is available. Typical examples of such polyepoxide compound include polyphenol glycidyl ethers such as bis(4-hydroxyphenyl)-2,2-propane, bis(4-hydroxyphenyl)-1,1-ethane, bis(4-hydroxyphenyl)-methane, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxydiphenylsulfone, phenolic novolak and cresol novolak, and their polymerized products. In the aforesaid polyepoxide compound, a polyphenol polyglycidyl ether having a number average molecular weight of at least about 380, preferably about 800 to about 2,000 and an epoxy equivalent of 190 to 2,000, preferably about 400 to 1,000 is especially preferable for high corrosion resistance. Most preferable is a polyepoxide compound represented by formula, wherein q is 0 to 7, especially 0 to 4. The epoxy resin derivative (A) can be formed by reacting the amine compound (A-1) with the epoxy resin (A-2). The reaction is presumably conducted, as shown in the following reaction scheme B, between the secondary amino group of the amine compound (A-1) and the epoxy group of the epoxy resin (A-2). wherein denotes a skeletal portion of an epoxy resin (provided for simplicity, only 1 epoxy group is shown in the above reaction scheme, but at least one other epoxy group is bound to ), and R 1 , R 2 and n are as defined above. The reaction of the epoxy resin (A-2) and the amine compound (A-1) proceeds by mere heating at a temperature of usually 50 to 140°C, preferably 70 to 120°C, and an alcoholic, ketonic or ethereal organic solvent may be used if required. A reaction ratio of the epoxy resin (A-2) and the amine compound (A-1) is not critical but can optionally be selected. In order to avoid gelation by an unreacted amino group or an epoxy group, it is advisable that an epoxy group/amino group equivalent ratio is 2/1 to 1/1, especially 1.5/1 to 1.05/1. When said ratio is outside the above range, it is advisable that part of the 1,2-epoxy group is blocked by previously reacting it with another reagent. The amine compound of formula (I) contains a hydrocarbon group (R 2 ) having 8 or more carbon atoms. Since this moiety acts as a plastic component, another plastic component is substantially unnecessary. However, when better smoothness of a coated surface is required, it is possible to use an epoxy compound instead of or conjointly with the aforesaid polyepoxide compound. Examples of the epoxy compound (A-2) include polyglycidyl ethers of alicyclic polyols such as bis(4-hydroxycyclohexyl)-2,2-propane and bis(4-hydroxycyclohexyl)-methane, polyglycidyl esters of polycarboxylic acids such as terephthalic acid and tetrahydrophthalic acid, and an epoxidized 1,2-polybutadiene/glycidyl (meth)acrylate copolymer. Moreover, the above polyepoxide compound may partially be reacted with a polyol such as polycaprolactonediol or polypropylene glycol, a polyether polyol, a polyester polyol, a polyamideamine such as dimeric acid polyamide, a polycarboxylic acid such as a carboxylterminated acrylonitrile/butadiene copolymer, or a polyisocyanate. It may further be glaft-polymerized with delta-4-caprolactone or an acrylic monomer. The epoxy resin derivative (A) can further be modified to adjust hydrophilic nature (solubility or dispersibility in water) and ameliorate smoothness of a coated surface and physical properties of a coated film. Modification method 1) Basicity and hydrophilic nature (water solubility or dispersibility) can be adjusted by reaction with an amine-type reactant containing active hydrogen and an amino group but free from an amide group. Examples of the amine-type reagent include primary amines such as methylamine, n- or iso-propylamine, monoethanolamine, ethylamine and n- or iso-propanolamine; secondary amines such as diethanolamine, diethylamine, N-ethylethanolamine, di-n- or di-iso-propanolamine and N-methylethanolamine; and polyamines such as ethylenediamine, diethylenetriamine, hydroxyethylaminoethylamine, ethylaminoethylamine, methylaminopropylamine, dimethylaminoethylamine and dimethylaminopropylamine. Moreover, basic compounds such as ammonia, formaldehydeoxazolidine, hydrazine, hydroxyethylhydrazine and N-hydroxyethylimidazoline are also available. Modification method 2) Basicity and hydrophilic nature of the resin derivative (A) may be adjusted by previously protonating an active hydrogen-free amine-type reagent and reacting the protonated reagent with an epoxy group to form a quaternary salt. Examples of the above reagent include tertiary amines such as triethylamine, triethanolamine, N,N-dimethylethanolamine, N-methyldiethanolamine, N,N-diethylethanolamine and N-ethyldiethanolamine. Other than the amine compound, a salt of a sulfide such as diethyl sulfide, diphenyl sulfide, tetramethylene sulfide or thiodiethanol, and boric acid, carbonic acid or an organocarboxylic acid may be reacted with the epoxy group to form a tertiary sulfonium salt. Moreover, a salt of triethylphosphine, phenyldimethylphosphine, diphenylmethylphosphine or triphenylphosphine and the above acid may be reacted with the epoxy group to form a quaternary phosphonium salt. Modification method 3) Smoothness of a coated film of the resin derivative may be adjusted by reaction with a reagent (a monocarboxylic acid, a monophenol or a monoalcohol). Examples of the reagent used in this case include 2-ethylhexanoic acid, linoreic acid, nonylphenol and 2-ethylhexanol. Modification method 4) Properties of a coated film can be modified by modifying the resin derivative via reaction with at least one type selected from a polyester, a polyether, a polyurethane and a polybutadiene containing a hydroxyl group, a carboxyl group and an amino group. Examples of the modifier used in this case include polycaprolactonediol, polypropylene glycol, dimeric acid polyamide, and a carboxyl-containing acrylonitrile/butadiene copolymer. It is advisable that the above-described modification methods 1) to 4) are carried out previous to the reaction between the epoxy resin (A-2) and the amine compound (A-1); said methods may be conducted either simultaneously with or after said reaction. The amount of the reagent or the modifier used to modify the epoxy resin is not particularly limited unless impairing the properties of the epoxy resin itself. The reagent or modifier/epoxy resin (A-2) ratio is usually not more than 1/3, preferably not more than 1/5. The epoxy resin derivative (A) produced as described above has itself film formability at room temperature or under heating and can be used as a main component in a coating resin composition or a resin composition for paint. On that occasion, to impart heat crosslink-curability to the composition, (i) a crosslinkable functional group capable of reacting with a hydroxyl group is introduced into a skeleton of the epoxy resin derivative (A) to give said derivative intermolecular crosslinkability or (ii) an external curing agent having a crosslinkable functional group can be blended. Examples of the crosslinkable functional group that can be introduced into the epoxy resin derivative (A) to give the intermolecular crosslinkability in (1) above include a blocked isocyanate group, a beta-hydroxy ester group, an alpha,beta-unsaturated carbonyl group, a N-methylol group and an epoxy group. From the aspects of low-temperature curability and bath stability, it is advisable that an isocyanage group blocked with a blocking agent having low-temperature dissociation property, a functional group having an active double bond (e.g. an isocyanate blocked with hydroxyethyl acrylate or N-methoxybutylacrylamide) or an epoxy group (e.g. a compound with an epoxy group directly bound to an alicyclic skeleton (including a bridged structure), EHPE-3150 - a tradename for a product of Daicel Chemical Industries, Ltd.) is introduced as a crosslinkable functional group. Examples of the external curing agent in (ii) above include compounds having at least 2 crosslinkable groups shown above in a molecule, such as blocked polyisocyanate compounds (including those showing low-temperature dissociation property and hving an active double bond), polycarboxylic acid beta-hydroxyethyl esters, malonic ester derivatives, methylolated melamines, methylolated ureas, and the above epoxy group-containing alicyclic compounds. When the epoxy resin derivative (A) is used as a coating resin composition, it is usually convenient that said derivative is dissolved or dispersed in water. The epoxy resin derivative (A) can be solubilized or dispersed in water by, for example, protonating the tertiary amino group of the epoxy resin derivative with a water-soluble organocarboxylic acid such as formic acid, acetic acid or lactic acid. The amount (neutralization value) of the acid used in the protonation cannot strictly be defined, but it is usually about 5 to 40, especially preferably 10 to 20 KOH mg per gram of the resin solids content. The coating resin composition containing the epoxy resin derivative (A) as the main comonent can contain, if required, a coloring pigment, an anticorrosive pigment, an extender pigment, a metallic pigment, an organic solvent, a curing catalyst and a surface active agent. The coating resin composition can be coated by a coating method known per se, such as dip coating, spray coating, brushing, etc. Cationic electrodeposition coating is especially preferable. A method and a device for electrodeposition coating can be a method and a device known per se in cathodical electrodeposition coating. In that case, it is advisable that a product being coated is used as a cathode and a stainless steel or carbon plate as an anode. The electrodeposition coating conditions are not particularly limited. Usually, a bath temperature is 20 to 30°C, a voltage 100 to 400 V (preferably 200 to 300 V), a current density 0.01 to 3 A/dM 2 , a current passage time 1 to 5 minutes, an electrode area ratio (A/C) 2/1 to 1/2, and a distance between electrodes 10 to 100 cm respectively. Moreover, electrodeposition is conducted under stirring. The coated film deposited on the product being coated in the cathode can be rinsed, and then based at about 140 to 200°C for curing. When the epoxy resin derivative (A) is used in such resin composition for the cationically electrodepositable paint, the hydroxyl groups of the epoxy resin derivative (A) are hydroxyl groups introduced from the amine compound (A-1), primary hydroxyl groups which can be introduced from alkanolamines as the cationizing agent, ring-opened caprolactones that may be introduced into epoxide compounds, and polyols, and secondary hydroxyl groups of the epoxy resin (A-2). Of these, the primary hydroxyl groups introduced from the amine compounds of formula (I) with R 1 =hydrogen atom and the alkanolamines shown in the modification method 1) are preferable. The content of the hydroxyl groups in the epoxy resin derivative (A) is usually 20 to 5,000, preferably 100 to 1,000, calculated as a hydroxyl equivalent. Especially preferable is that the primary hydroxyl equivalent is 200 to 1,000. The content of the cationic groups is preferably higher than the lower limit necessary to stably disperse the epoxy resin derivative (A) in an aqueous medium. It is advisable that the total amount of the cationizing agent introduced from the amine compound (A-1) and the other cationizing agent is usually 10 to 200, preferably 10 to 80, more preferably 20 to 60, calculated as an amine value [KOH(mg/g-solids content)]. However, even if the cationic group content is less than 3, it is possible to use it after making it an aqueous dispersion by the use of a surface active agent; in this case, however, it is desirable to adjust the cationic group so as to make the pH of the aqueous dispersed composition, usually 4 to 9, more preferably 6 to 7. The epoxy resin derivative (A) used in the present invention has hydroxyl groups and cationic groups and is desirably free from free epoxy groups as a rule. Resin composition for a cationically electrodepositable paint A resin composition for a cationically electrodepositable paint is prepared by using the aforesaid epoxy resin derivative (A). For preparing the resin composition for a cathodically electrodepositable paint of the present invention, for example, the epoxy resin derivative (A) is stably dispersed in water. Then, as required, the resulting aqueous dispersion is blended with a color pigment such as carbon black, titanium white, white lead, lead oxide and red iron oxide; an extender pigment such as clay and talc; an anticorrosive pigment such as strontium chromate, lead chromate, basic lead chromate, red lead, lead silicate, basic lead silicate, lead phosphate, basic lead phosphate, lead tripolyphosphate, lead silicochromate, chrome yellow, lead cyanamide, calcium plumbate, lead suboxide, lead sulfate and basic lead sulfate; or further with other additives. As the other additives that can be blended, for example, a small amount of a dispersant or a nonionic surface active agent as a cissing preventing agent of the coated surface; and curing promotor may be cited. Especially, for making an electrodeposited paint sufficiently curable at a low temperature of not more than 160°C, it is effective to add one kind or at least two kinds of metallic compound selected from among a lead compound, a zirconium compound, a cobalt compound, an aluminum compound, a manganese compound, a copper compound, a zinc compound, an iron compound, a chromium compound and a nickel compound as a catalyst. Specific examples of these metal compounds include chelated compounds such as zirconium acetyl acetonate, cobalt acetyl acetonate, aluminum acetyl acetonate and manganese acetyl acetonate; a chelation reaction product of compounds having beta-hydroxyamino structures with lead oxide (II); and carboxylates such as lead 2-ethyl hexanoate, lead oenanthate, naphthex lead, lead octanoate, lead benzoate, lead acetate, lead lactate, lead formate, lead glycoate and octanoate zircinium. Said metal compounds may be used in an amount calculated as a metal content based on the weight of the total solids content of the epoxy resin derivative (A) of generally not more than 10 % by weight, preferably not more than 5 % by weight. The thickness of a paint film obtained by electrodepositing the so prepared resin composition for a cathodically electrodepositable paint on a proper substrate is not strictly restricted; however, generally, the thickness within the range of 3 to 300 microns based on the cured paint film is suitable. The paint film can be cured with heating at a temperature of, for example, 70 to 250°C, preferably 120 to 160°C. A method of forming an electrodeposited paint film on the substrate using the resin composition for a cathodically electrodepositable paint of the present invention is not particularly restricted, but ordinary conditions for cathodically electrodepositing may be used. For example, the epoxy resin derivative (A) according to this invention is, as mentioned above, dispersed in water, the resulting aqueous dispersion is blended with, as required, pigments, a curing catalyst and other additives, further, the mixture is diluted to the concentration of the solids content of the bath within the range of 5 to 40 % by weight, preferably 10 to 25 % by weight, and the bath pH is adjusted within the range of 5 to 8, preferably 5.5 to 7. Next, using this electrodeposition bath, electrodeposition is carried out under the following conditions with, for example, a carbon plate (5 cm x 15 cm x 1 cm) being used as an anode and for example, a zinc phosphate-treated steel (5 cm x 15 cm x 0.7 mm) being used as a cathode. Bath temperature: 20 to 35°C, preferably 25 30°C Direct current Current density: 0.005 to 2 A/cm 2 , preferably 0.01 to 1 A/cm 2 Voltage: 10 to 500 V, preferably 100 to 300 V Power feeding time: 0.5 to 5 min., preferably 2 to 3 min. After the electrodeposition coating, the coated product can be drawn up from the electrodeposition bath, and rinsed with water. The moisture contained in the electrodeposition coated film is removed by a drying means such as a heat, and the resulting product is then heat cured by heating as mentioned above. In the epoxy resin derivative (A) in the coating resin composition of this invention, the tertiary amino group introduced from the amine comound (A-1) makes water dispersibility in low neutralization good, the hydrocarbon group containing 4 or more carbon atoms gives smoothness of a coated surface and an active hydrogencontaining cationic group is absent, so that even if conjointly using as a crosslinkable functional group an isocyanate group blocked with a blocking agent having low-temperature dissociation property or a functional group having an active double bond (e.g. an isocyanate group blocked with hydroxyethyl acrylate or N-methoxybutylacrylamide), a desirable cationically electrodepositable coating or aqueous coating resin composition can be provided without impairing stability. The primary hydroxyl groups introduced from said amine can be reacted with functional groups capable of reacting with said hydroxyl groups without sacrificing corrosion resistance, making it possible to provide a cationically electrodepositable coating or an aqueous coating resin composition having good corrosion resistance. The following Examples illustrate this invention more specifically. However, this invention is not limited thereto. Parts and percentages in said Examples are all by weight unless otherwise indicated. I. Preparation Examples (1) Amine compound (A-1) 1) Amine compound (A-1-1) A reaction vessel fitted with a thermometer, a stirrer, a reflux condenser, and a water separator was charged with 285 parts of stearic acid, 104 parts of hydroxyethylaminoethylamine and 80 parts of toluene. With mixing and stirring, the mixture was progressively heated, and toluene was removed if required. While raising the temperature, 18 parts of a reaction water was removed by separation, and the remaining toluene was removed under reduced pressure to obtain an amine compound (A-1-1) having an amine value of 150, a hydroxyl value of 151 and a solidification point of 76°C. 2) Amine compound (A-1-2) A reaction vessel fitted with a thermometer, a stirrer, a reflux condenser, and a water separator was charged with 283 parts of a tall oil fatty acid, 104 parts of hydroxyethylaminoethylamine and 80 parts of toluene. With mixing and stirring, the mixture was progressively heated, and toluene was removed if required. While elevating the temperature, 18 parts of a reaction water was removed by separation, and the remaining toluene was then removed under reduced pressure to obtain an amine compound (A-1-2) having an amine value of 151, a hydroxyl value of 152 and a solidification point of 20°C or lower. 3) Amine compound (A-1-3): A reaction vessel fitted with a thermometer, a stirrer, a reflux condenser, a water separator was charged with 300 parts of 12-hydroxystearic acid, 104 parts of hydroxyethylaminoethylamine and 80 parts of toluene. With mixing and stirring, the mixture was progressively heated, and toluene was removed if required. While elevating the temperature, 18 parts of a reaction water was removed by separation, and the remaining toluene was then removed under reduced pressure to obtain an amine compound (A-1-3) having an amine value of 148, a hydroxyl value of 149 and a solidification point of 69°C. 4) Partially blocked polyisocyanate compound (B-NCO-1) A reaction vessel fitted with a thermometer, a stirrer, a reflux condenser and a dropping funnel was charged dwith 222 parts of isophorone diisocyanate, 37 parts of methyl isobutyl ketone, 0.1 part of dibutyltin dilaurate and 1 part of hydroquinone monomethyl ether. Hydroxyethyl acrylate (116 parts) was added dropwise at 100°C, and the reaction was run until a NCO value reached 112 to obtain a partially blocked polyisocyanate compound (B-NCO-1). 5) Sample for comparison A reaction vessel fitted with a thermometer, a stirrer, a reflux condenser and a water separator was charged with 103 parts of diethylenetriamine and 314 parts of methyl isobutyl ketone. With mixing and stirring, the mixture was progressively heated. While raising the temperature, 36 parts of a reaction water was removed by separation to obtain a sample (1) for comparison. (3) Pigment pastes 1) Pigment paste (P-1) To the epoxy resin derivative [A-2] (12.5 parts) which will be described in Example 2 later was added 4.4 parts of 10 % formic acid. Fifteen parts of deionized water was then added with stirring. Ten parts of titanium white, 10 parts of clay, 1 part of carbon and 2 parts of basic lead silicate were further added to the mixture. The resulting mixture was dispersed in a ball mill for 24 hours and 11 parts of deionized water was further added to obtain a paste (P-1) having a solids content of 50 %. 2) Pigment paste for comparison (P-2) A pigment paste (P-2) was formed as in (P-1) except adding 1.5 parts of dibutyltin dilaurate. II. Examples Example 1: A reaction vessel fitted with a thermometer, a stirrer and a reflux condenser was charged with 988 parts of bisphenol A diglycidyl ether having an epoxy equivalent of about 190, 365 parts of bisphenol A and 10.5 parts of diethanolamine. The reaction was run at 120°C until the epoxy equivalent reached 682 (a number average molecular weight 1,370). Then, the reaction mixture was diluted with 343 parts of ethylene glycol monobutyl ether and cooled. Subsequently, while keeping the temperature at 80°C, 126 parts of diethanolamine and 224 parts of the amine compound (A-1-1) were added. Until increase of viscosity stopped, the reaction was conducted. Thereafter, 228 parts of methyl isobutyl ketone was added to obtain an epoxy resin derivative (A-1) having a solids content of 75 %, a primary hydroxyl equivalent of 535 and an amine value of 62. Example 2: A reaction vessel fitted with a thermometer, a stirrer and a reflux condenser was charged with 988 parts of bisphenol A diglycidyl ether having an epoxy equivalent of about 190, 365 parts of bisphenol A and 10.5 parts of diethanolamine. The reaction was run at 120°C until the epoxy equivalent reached 682 (a number average molecular weight 1,370). Then, the reaction mixture was diluted with 343 parts of ethylene glycol monobutyl ether and cooled. While keeping the temperature at 80°C, 126 parts of diethanolamine and 224 parts of the amine compound (A-1-2) were added, and the reaction was conducted until increase of viscosity stopped. Subsequently, 228 parts of methyl isobutyl ketone was added to obtain an epoxy resin derivative (A-2) having a solids content of 75 %, a primary hydroxyl equivalent of 535 and an amine value of 62. Example 3: A reaction vessel fitted with a thermometer, a stirrer and a reflux condenser was charged with 912 parts of bisphenol A diglycidyl ether having an epoxy equivalent of about 190, 365 parts of bisphenol A, 136 parts of polypropylene glycol diglycidyl ether having an epoxy equivalent of 340 and 10.5 parts of diethanolamine. The reaction was run at 120°C until the epoxy equivalent reached 712 (a number average molecular weight 1,440). Thereafter, the reaction mixture was diluted with 355 parts of ethylene glycol monobutyl ether and cooled. While keeping the temeprature at 80°C, 126 parts of diethanolamine and 227 parts of the amine compound (A-1-3) were added, and the reaction was carried out until increase of viscosity stopped. Thereafter, 237 parts of methyl isobutyl ketone was added to afford an epoxy resin derivative (A-3) having a solids content of 75 %, a primary hydroxyl equivalent of 557 and an amine value of 60. Example 4: A reaction vessel fitted with a thermometer, a stirrer, a reflux condenser and a dropping funnel was charged with 988 parts of bisphenol A diglycidyl ether having an epoxy equivalent of about 190, 365 parts of bisphenol A and 10.5 parts of diethanolamine. The reaction was run at 120°C until the epoxy equivalent reached 682 (a number average molecular weight 1370). Then, the reaction mixture was diluted with 236 parts of methyl isobutyl ketone and cooled. While keeping the temperature at 80°C, 126 parts of diethanolamine and 224 parts of the amino compound (A-1-1) were added, and the reaction was conducted until increase of viscosity stopped. Subsequently, 376 parts of B-NCO-1 was added dropwise, it was confirmed by IR that the NCO residue disappeared, and 410 parts of ethylene glycol monobutyl ether was added to obtain an epoxy resin derivative (A-4) having a solids content of 75 %, a primary hydroxyl equivalent of 641 and an amine value of 52. Comparative Example 1: A reaction vessel fitted with a thermometer, a stirrer and a reflux condenser was charged with 912 parts of bisphenol A diglycidyl ether having an epoxy equivalent of about 190, 365 parts of bisphenol A, 136 parts of polypropylene glycol diglycidyl ether having an epoxy equivalent of 340 and 10.5 parts of diethanolamine. The reaction was run at 120°C until the epoxy equivalent reached 712. Subsequently, the reaction mixture was diluted with 355 parts of ethylene glycol monobutyl ether and cooled. While maintaining the temperature at 80°C, 189 parts of diethanolamine was added. Until increase of viscosity stopped, the reaction was carried out. Then, 183 parts of methyl isobutyl ketone was added to obtain a resin (1) for comparison. Comparative Example 2: A reaction vessel fitted with a thermometer, a stirrer and a reflux condenser was charged with 988 parts of bisphenol A diglycidyl ether having an epoxy equivalent of about 190, 365 parts of bisphenol A and 10.5 parts of diethanolamine. The reaction was run at 120°C until the epoxy equivalent reached 682. Then, the reaction mixture was diluted with 343 parts of ethylene glycol monobutyl ether and cooled. While maintaining the temperature at 80°C, 168 parts of diethanolamine and 76 parts of the sample (1) for comparison. The reaction was conducted until increase of viscosity stopped. Thereafter, 138 parts of methyl isobutyl ketone was added to obtain a resin (2) for comparison. Comparative Example 3: A reaction vessel fitted with a thermometer, a stirrer and a reflux condenser was charged with 912 parts of bisphenol A diglycidyl ether having an epoxy equivalent of about 190, 365 parts of bisphenol A, 136 parts of polypropylene glycol diglycidyl ether having an epoxy equivalent of 340 and 10.5 parts of diethanolamine. The reaction was run at 120°C until the epoxy equivalent reached 712. Then, the reaction mixture was diluted with 329 parts of ethylene glycol monobutyl ether and cooled. While keeping the temperature at 80°C, 168 parts of diethanolamine and 76.3 parts of the sample (1) for comparison were added. The reaction was conducted until increase of viscosity stopped, and 196 parts of methyl isobutyl ketone was added to obtain a resin (3) for comparison. Comparative Example 4: A reaction vessel fitted with a thermometer, a stirrer, a reflux condenser and a dropping funnel was charged with 912 parts of bisphenol A diglycidyl ether having an epoxy equivalent of about 190, 365 parts of bisphenol A, 136 parts of polypropylene glycol diglycidyl ether having an epoxy equivalent of 340 and 10.5 parts of diethanolamine. The reaction was conducted at 120°C until the epoxy equivalent reached 712. Thereafter, the reaction mixture was diluted with 233 parts of methyl isobutyl ketone and cooled. While keeping the temperature at 80°C, 168 parts of diethanolamine and 76.3 parts of the sample (1) for comparison were added, and the reaction was carried out until increase of viscosity stopped. Thereafter, 376 parts of (B-NCO-1) was added dropwise, it was confirmed by IR that the NCO residue disappeared, and 367 parts of ethylene glycol monobutyl ether was added to obtain a resin (4) for comparison. Example 5: One hundred parts of the epoxy resin derivative (A-1) (a resin solids content 75 %), 25 parts of methyl ethyl ketoximate blocked 4,4'-diphenylmethane diisocyanate and 1 part of polypropylene glycol (PP-4000, a tradename for a product of Sanyo Chemical Industries Ltd.) were mixed, and 1.70 parts of acetic acid was then added. While heating the mixture at 60°C with stirring, deionized water was gradually added and the mixture was dispersed in water to obtain a stable emulsion having a resin solids content of 30 %. A particle diameter of the emulsion was 0.2 micron. To this were added 3 parts of basic lead silicate, 13 parts of titanium white, 0.3 part of carbon black, 3 parts of clay, 2 parts of dibutyltin oxide and 1 part of a nonionic surface active agent 142B (a tradename for a product of Daiichi Kogyo Seiyaku Co., Ltd.). The pigments were dispersed with a ball mill until a particle diameter reached 10 microns or less. The pigment dispersion was further diluted with deionized water until the solids content of 20 % was reached. After open-stirring at 28°C for 1 day, the resulting product was electrodeposited on a zinc phosphate treated steel plate (Bt #3080) at a bath temperature of 28°C and a voltage of 250 V for 3 minutes, and baked at 160°C for 20 minutes to afford a coated film having a thickness of about 20 microns and showing excellent smootheness. After the paint was further stirred at 28°C for 2 weeks in a closed state, the same electrodeposition was conducted to obtain a coated film having a thickness of about 20 microns and showing excellent smoothness. Example 6: Eighty five parts of the epoxy resin derivative (A-2) (a resin solids content 75 %), 25 parts of the blocked isocyanate in Example 5 and 1 part of polypropylene glycol (PP-4000, a tradename for a product of Sanyo Kasei Kogyo K.K.) were mixed, and 1.70 parts of acetic acid was then added. While heating the mixture at 60°C with stirring, deionized water was gradually added and the mixture was dispersed in water to obtain a stable emulsion having a resin solids content of 30 %. A particle diameter of the emulsion was 0.15 micron. To 15 parts of the epoxy resin derivative (A-2) (a resin solids content 75 %) were added 6 parts of ethylene glycol monobutyl ether, 4 parts of basic lead silicate, 13 parts of titanium white, 0.3 part of carbon black, 3 parts of clay and 1 part of a nonionic surface active agent 142B (a tradename for a product of Daiichi Kogyo Seiyaku K.K.). The pigments were dispersed with a ball mill until a particle diameter of 10 microns or less was reached. The resulting pigment dispersion was mixed with the above emulsion, and the mixture was diluted to a solids content of 20 % with deionized water. After open-stirring at 28°C for 1 day, the resulting mixture was electrodeposited on a zinc phosphate-treated steel plate (Bt #3080) at a bath temperature of 28°C and a voltage of 250 V for 3 minutes, and baked at 160°C for 20 minutes to obtain a coated film having a thickness of about 20 microns and showing excellent smoothness. After the paint was further stirred at 28°C for 2 weeks in a closed state, the same electrodeposition was carried out to obtain a coated film having a thickness of about 20 microns and showing excellent smoothness. Example 7: One hundred parts of the epoxy resin derivative (A-3) (a resin solids content 75 %), 25 parts of ethylene glycol mono-2-ethylhexyl ether blocked 4,4'-diphenylmethane diisocyanate and 1 part of polypropylene glycol (PP-4000, a tradename for a product of Sanyo Kasei Kogyo K.K.) were mixed, and 1.70 parts of acetic acid was then added. While heating the mixture at 60°C with stirring, deionized water was gradually added and the mixture was dispersed in water to obtain a stable emulsion having a resin solids content of 30 %. A particle diameter of the emulsion was 0.15 micron. To this were added 3 parts of basic lead silicate, 13 parts of titanium white, 0.3 part of carbon black, 3 parts of clay, 2 parts of dibutyltin oxide and 1 part of a nonionic surface active agent 142B (a tradename for a product of Daiichi Kogyo Seiyaku K.K.). The pigments were dispersed with a ball mill until a particle diameter of 10 microns or less was reached. The pigment dispersion was diluted to a solids content of 20 % with deionized water. After open-stirring at 28°C for 1 day, the pigment dispersion was electrodeposited on a zinc phosphate-treated steel plate (Bt #3080) at a bath temperature of 28°C and a voltage of 250 V for 3 minutes, and baked at 160°C for 20 minutes to afford a coated film having a thickness of about 25 microns and showing excellent smoothness. After the paint was further stirred at 28°C for 2 weeks in a closed state, the same electrodeposition was carried out to obtain a coated film having a thickness of about 25 microns and showing excellent smoothness. Example 8: After 133 parts of the epoxy resin derivative (A-4) (a resin solids content 75 %) and 1 part of polypropylene glycol (PP-4000, a tradename for a product of Sanyo Kasei Kogyo K.K.) were mixed, 1.70 parts of acetic acid was added. While heating the mixture at 60°C with stirring, deionized water was gradually added and the mixture was dispersed in water to obtain a stable emulsion having a resin solids content of 30 %. A particle diameter of the emulsion was 0.18 micron. To this emulsion were added 3 parts of basic lead silicate, 13 parts of titanium white, 0.3 part of carbon black, 3 parts of clay, 2 parts of dibutyltin oxide and 1 part of a nonionic surface active agent 142B (a tradename for a product of Daiichi Kogyo Seiyaku K.K.). The pigments were dispersed with a ball mill until a particle diameter of 10 microns or less was reached. The pigment dispersion was further diluted to a solids content of 20 % with deionized water. After open-stirring at 28°C for 1 day, the resulting dispersion was electrodeposited on a zinc phosphate-treated steel plate (Bt #3080) at a bath temperature of 28°C and a voltage of 250 V for 3 minutes, and baked at 160°C for 20 minutes to obtain a coated film having a thickness of about 20 microns and showing excellent smoothness. After the paint was thrther stirred at 28°C for 2 weeks in a closed state, the same electrodeposition was carried out to obtain a coated film having a thickness of about 20 microns and showing excellent smoothness. Comparative Example 5: One hundred parts of the resin (1) for comparison (a resin solids content 75 %), 25 parts of ethylene glycol mono-2-ethylhexyl ether blocked 4,4'-diphenylmethane diisocyanate and 1 part of polypropylene glycol (PP-4000, a tradename for a product of Sanyo Kasei Kogyo K.K.) were mixed, and 1.70 parts of acetic acid was then added. While heating the mixture at 60°C with stirring, deionized water was gradually added and the mixture was dispersed in water to form an emulsion having a resin solids content of 30 %. A particle diameter of the emulsion was 0.6 micron or more. Therefore, when the amount of the acid was increased to 2.13 parts, a solution was formed. However, the emulsion was separated and sedimented at 30°C in 1 week. Comparative Example 6: One hundred parts of the resin (2) for comparison (a resin solids content 75 %), 25 parts of ethylene glycol mono-2-ethylhexyl ether blocked 4,4'-diphenylmethane diisocyanate and 1 part of polypropylene glycol (PP-4000, a tradename for a product of Sanyo Kasei Kogyo K.K.) were mixed, and 1.70 parts of acetic acid was then added. While heating the mixture at 60°C with stirring, deionized water was gradually added and the mixture was dispersed in water to produce an emulsion having a resin solids content of 30 %. A particle diameter of the emulsion was however 0.2 micron. To this emulsion were added 3 parts of basic lead silicate, 13 parts or titanium white, 0.3 part of carbon black, 3 parts of clay, 2 parts of dibutyltin oxide and 1 part of a nonionic surface active agent 142B (a tradename for a product of Daiichi Kogyo Seiyaku K.K.). The pigments were dispersed with a ball mill until a particle diameter of 10 microns or less was reached. The dispersion was further diluted to a solids content of 20 % with deionized water. After open-stirring at 28°C for 1 day, the resulting product was electrodeposited on a zinc phosphate-treated steel plate (Bt #3080) at a bath temperature of 28°C and a voltage of 250 V for 3 minutes, and baked at 160°C for 20 minutes to obtain a coated film having a thickness of about 15 microns. However, it had a coated surface showing poor smoothness. Comparative Example 7: Eighty five parts of the resin (3) for comparison (a resin solids content 75 %), 25 parts of the blocked isocyanate in Example 5 and 1 part of polypropylene glycol (PP-4000, a tradename for a product of Sanyo Kasei Kogyo K.K.) were mixed, and 1.70 parts of acetic acid was added. While heating the mixture at 60°C with stirring, deionized water was gradually added and the mixture was dispersed in water to obtain a stable emulsion having a resin solids content of 30 %. A particle diameter of the emulsion was 0.15 micron. To 15 parts of the resin (3) for comparison (a resin solids content 75 %) were added 6 parts of ethylene glycol monobutyl ether, 4 parts of basic lead silicate, 13 parts of titanium white, 0.3 part of carbon black, 3 parts of clay and 1 part of a nonionic surface active agent 142B (a tradename for a product of Daiichi Kogyo K.K.). The pigments were dispersed with a ball mill until a particle diameter of 10 microns or less was reached. The resulting pigment dispersion was mixed with the above emulsion, and the mixture was further diluted to a solids content of 20 % with deionized water. After open-stirring at 28°C for 1 day, the resulting product was electrodeposited on a zinc phosphate-treated steel plate (Bt #3080) at a bath temperature of 28°C and a voltage of 250 V for 3 minutes, and baked at 160°C for 20 minutes to obtain a smooth coated film having a thickness of about 20 microns. After this paint was further stirred at 28°C for 2 weeks in a closed state, the same electrodeposition was carried out. Then, a coated surface having very poor smoothness was provided. Comparative Example 8: The resin (4) for comparison (133 parts: a resin solids content 75 %) and 1 part of polypropylene glycol (PP-4000, a tradename for a product of Sanyo Kasei Kogyo K.K.) were mixed, and 1.70 parts of acetic acid was then added. While heating the mixture at 60°C with stirring, deionized water was gradually added, and the mixture was dispersed in water to obtain a stable emulsion having a resin solids content of 30 %. A particle diameter of the emulsion was 0.18 micron. To this emulsion were added 3 parts of basic lead silicate, 13 parts of titanium white, 0.3 part of carbon black, 3 parts of clay, 2 parts of dibutyltin oxide and 1 part of a nonionic surface active agent 142B (a tradename for a product of Daiichi Kogyo Seiyaku K.K.). The pigments were dispersed with a ball mill until a particle diameter of 10 microns or less was reached. Then, gelation occurred. Comparative Example 9: Thirty nine parts of monoethanolamine was maintained in a reaction vessel at 60°C, and 100 parts of N,N-dimethylaminopropylacrylamide was added dropwise. The reaction was run at 60°C for 5 hours to obtain a monoethanolamine adduct of N,N-dimethylaminopropylacrylamide. Separately, 950 parts of bisphenol A diglycidyl ether having an epoxy equivalent of 190, 340 parts of propylene glycol diglycidyl ether having an epoxy equivalent of 340, 456 parts of bisphenol A and 21 parts of diethanolamine were charged and heated to 120°C. The reaction was conducted until an epoxy value reached 1.02 mmols/g. Subsequently, the reaction mixture was diluted with 656 parts of ethylene glycol monobutyl ether and cooled. While keeping the temperature at 100°C, 158 parts of diethanolamine and 43 parts of the monoethanolamine adduct of N,N-dimethylaminopropylacrylamide were added. The reaction was run until increase of viscosity stopped. There resulted a resin (5) for comparison having a resin solids content of 75 %, a primary hydroxyl equivalent of 518 and an amine value of 54.

Claims: A coating resin composition composed as main component of an epoxy resin derivative obtained by reacting an amine compound containing hydroxyl groups, secondary amino groups and amide groups represented by formula wherein n is an integer of 1 to 6, R 1 denotes a hydrogen atom, a methyl group or an ethyl group, and R 2 denotes a hydrocarbon group with 8 to 36 carbon atoms which may contain a hydroxyl group and/or a polymerizable unsaturated group with the epoxy groups of an epoxy resin. The coating resin composition of claim 1 wherein the content of the hydroxyl groups of the amine compound is 44 to 350 calculated as a hydroxyl value. The coating resin composition of claim 1 wherein the content of the secondary amino groups of the amine compound is 88 to 350 calculated as an amine value. The coating resin composition of claim 1 wherein the amine compound is obtained by reacting a diamine compound represented by formula wherein R 1 is as defined in claim 1, with a monocarboxylic acid represented by formula R 2 -COOH wherein R 2 is as defined in claim 1. The coating resin composition of claim 4 wherein the diamine compound is hydroxyethylaminoethylamine or N-hydroxyethylethylenediamine. The coating resin composition of claim 4 wherein the monocarboxylic acid is stearic acid, oleic acid or 12-hydroxystearic acid. The coating resin composition of claim 1 wherein the epoxy resin derivative contain primary hydroxyl groups and cationic groups formed by reaction of an amine compound and epoxy groups. The coating resin composition of claim 1 wherein the epoxy resin derivative is a reaction product obtained by reacting epoxy groups of a polyepoxide compound formed from a polyphenol compound and epichlorohydrin with the amine compound of formula (I). The coating resin composition of claim 8 wherein the polyepoxide compound is a polyglycidyl ether of a polyphenyl compound having a number average molecular weight of about 800 to about 2,000 and an epoxy equivalent of 190 to 2,000. The coating resin composition of claim 8 wherein the polyepoxide compound is a compound represented by formula wherein q is 0 to 7. The coating resin composition of claim 1 wherein the epoxy resin derivative has a hydroxyl equivalent of 20 to 5,000. The coating resin composition of claim 1 wherein the epoxy resin derivative has a primary hydroxyl equivalent of 200 to 1,000. The coating resin composition of claim 1 wherein the content of the cationic groups of the epoxy resin derivative is 3 to 200 calculated as KOH (mg/g-solids content). A cationically electrodepositable paint composition composed of a water-solubilized or water-dispersed product of the epoxy resin derivative of claim 1 which is protonated by neutralization with an acid. An article electrodeposition coated with the cationically electrodepositable paint composition of claim 14.

Inventors: FUJIBAYASHI TOSHIO, NAGAOKA HARUO, FUJIBAYASHI, TOSHIO, NAGAOKA, HARUO
Applicants: KANSAI PAINT CO LTD, KANSAI PAINT CO. LTD.
Application year: 1991
Main classification: C08G59
IPC codes: C08G59, C09D5