JPH0320425B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a water-soluble or water-dispersible coating composition, particularly a coating composition suitable for cationic electrodeposition coating in which the object to be coated is used as a cathode for electrodeposition coating. More specifically, the present invention relates to a composition for cationic electrodeposition paint that can provide an electrodeposition paint having a PH value of 6 or more and a coating film having extremely excellent antirust properties. Cationic electrodeposition paints have much better anti-corrosion properties than anionic electrodeposition paints, so their usage has been increasing in recent years, including in the automotive coating field. Various proposals have been made regarding the resin composition used in this cationic electrodeposition paint, but the ones actually used are, for example, bisphenol A/
An epoxy resin such as an epichlorohydrin condensation type epoxy resin is reacted with a primary amine or a secondary amine, then a blocking isocyanate or the like is added to impart thermosetting properties, and neutralized with an acid to make it water-soluble or water-dispersible. It is something that has been done by nature. When such cationic electrodeposition paints are actually used, the pH of the electrodeposition paints becomes a problem. That is, if the pH of the electrocoating paint is low, it will cause serious corrosion to the electrocoating equipment, resulting in accidents such as punctures in various pipes and electrocoat tanks. Therefore, the pH of the electrodeposition paint is 5.0 or higher,
It is said that 6.0 or higher is desirable.
Therefore, the amino group-containing resin used in cationic electrodeposition coating has excellent rust prevention properties for the resulting coating film, and at the same time, the pH of the electrodeposition coating obtained using it.
However, as mentioned above, it is necessary that the value is 5.0 or more, preferably 6.0 or more. However, until now, no amino group-containing resin suitable for cationic electrodeposition coating has been known, which provides a coating film with excellent rust prevention ability and at the same time provides an electrodeposition coating material with a high pH. For example, in Japanese Patent Publication No. 55-34291, the first
It is disclosed that a cationic electrodeposition paint containing an epoxy resin modified with a hydroxylamino group containing a class hydroxyl group provides a coating film having good rust prevention ability even without the use of a rust prevention pigment. Such hydroxylamine-modified epoxy resins have a drawback in that the pH of electrodeposition paints obtained using them is low because the basicity of the amino groups is low. Furthermore, JP-A No. 54-93024 discloses a composition for cationic electrodeposition paint that uses a resin having a primary amino group in its molecule and gives a high pH. Even in the composition for electrodeposition coating, the amount of resin having primary amino groups is adjusted to the required amount.
If the pH is increased until the pH is reached, the reaction between isocyanate groups and hydroxyl groups will occur during heat curing.
The reaction between the isocyanate group and the primary amino group is
Since the process progresses too quickly, gelation occurs too quickly, resulting in a disadvantage that complete curing of the coating film is hindered and the antirust ability is reduced. The present inventors have worked diligently to develop an amino group-containing resin suitable for cationic electrodeposition coating, which does not have the above drawbacks, provides an electrodeposition coating with a high pH, and provides a coating film with extremely excellent rust prevention ability. The present invention was developed after conducting research. That is, in the present invention, at least 2
decomposes the ketimine group of the product obtained by reacting an epoxy resin having at least one epoxy group with a polyamine-ketimine derivative having one secondary amino group and at least one ketimine group in one molecule. A reaction product having at least two tertiary amide groups and at least two primary amino groups in one molecule obtained by On the other hand, the present invention relates to a composition for a cationic electrodeposition coating, which contains an amino group-containing resin obtained by reacting glycidol in a proportion of 0.2 to 2.0 moles. Examples of the epoxy resin having at least two epoxy groups in one molecule used in the present invention include bisphenol A/epichlorohydrin condensation epoxy resin, bisphenol A/β
-Methyl epichlorohydrin condensation type epoxy resin, hydrogenated bisphenol A/epichlorohydrin condensation type epoxy resin, etc., diglycidyl ether of aliphatic polyether, diglycidyl ester of dicarboxylic acid, novolak type epoxy resin, etc. are particularly suitable. Examples include bisphenol A/epichlorohydrin condensation epoxy resin (commercially available products include Epicote 828, Epicote 1001, Epicote 1004, and Epicote 1007 manufactured by Yuka Ciel Epoxy Co., Ltd.). . These epoxy resins may be used as they are; for example, one or two epoxy resins may be used in one molecule.
The molecular weight may be increased by reacting with a compound containing hydroxyl, carboxyl group, thiol group, primary amino group, secondary amino group, etc. to extend the molecular chain and increase the molecular weight. In that case, the molecular weight of the product is 700 to 8000 in number average molecular weight,
Preferably it is 1500-6000. The number average molecular weight is
If it is less than 700, the water solubility of the final cationic electrodeposition coating composition will be too high, and even if it is electrodeposited, the coating will run off when washed with water, and a uniform coating will not be obtained. Mechanical properties and anti-corrosion properties of the membrane deteriorate. Furthermore, if the number average molecular weight exceeds 8,000, a stable aqueous solution or aqueous dispersion cannot be obtained unless the neutralization rate with an acid is extremely increased. Not only is it impossible to obtain a coating that adheres to the coating, but the melt viscosity increases during heating and curing, and gelation occurs too quickly, making it difficult to obtain a smooth coating, and as a result, complete curing is prevented. The rust prevention ability of the paint film also decreases. Further, when the epoxy resin contains hydroxyl groups, the hydroxyl groups may be reacted with a partially blocked organic polyisocyanate. The amount of this partially blocked organic polyisocyanate is not particularly limited, but usually the amount of reacting hydroxyl groups is
It is preferable to allow for no more than half the amount of available hydroxyl groups. This partially blocked organic polyisocyanate is obtained by reacting a part of the isocyanate groups of the organic polyisocyanate with a blocking agent. Although stable, it is usually reactive with hydroxyl groups or amino groups at temperatures of 90 to 250°C.
It contains at least one blocked isocyanate group and an average of about one free, unblocked isocyanate group. Partially blocked organic polyisocyanates include, for example, m- or p-phenylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4- or 2,6-tolylene diisocyanate, hexamethylene diisocyanate, isophorone. Aromatic or aliphatic diisocyanates such as diisocyanates, and adducts of these with polyols such as ethylene glycol, propylene glycol, and trimethylolpropane, are combined with blocking agents such as methyl alcohol, ethyl alcohol, propyl alcohol, and isopropyl alcohol. , aliphatic or aromatic alcohols such as butyl alcohol, hexyl alcohol, 2-ethylhexyl alcohol, cyclohexyl alcohol, benzyl alcohol, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, glycol ethers: 2-hydroxyethyl acrylate, Acrylic monomers containing hydroxyl groups such as 2-hydroxyethyl methacrylate;
Phenols such as phenol and cresol; ε
- obtained by reacting lactams such as caprolactam; oximes such as methyl ethyl ketoxime in such a way that on average about one unblocked free isocyanate group remains; It is convenient if the reactivity of 2,
4- or 2,6-tolylene diisocyanate,
Isophorone diisocyanate and the like are preferred. Suitable blocking agents include, for example, methyl alcohol, hexyl alcohol, 2-ethylhexyl alcohol, and ethylene glycol monobutyl ether. Polyamine-ketimine derivatives having one secondary amino group and at least one ketimine group in one molecule (hereinafter simply referred to as
(referred to as polyamine-ketimine derivatives),
It is derived by reacting a polyamine having one secondary amino group and at least one primary amino group in one molecule with a ketone. Here, examples of polyamines having one secondary amino group and at least one primary amino group in one molecule include ethylaminoethylamine and methylaminopropylamine. Polyamines having one secondary amino group and one primary amino group; Examples include polyamines having primary amino groups. In addition, examples of ketones include low molecular weight ketones that are easily distilled out together with water, such as acetone, methyl ethyl ketone, and methyl isobutyl ketone (these are preferably used in the present invention).
Examples include diethyl ketone, methylpropyl ketone, ethyl isopropyl ketone, cyclohexanone, cyclopentanone, and acetophenone. The reaction resulting in the polyamine-ketimine derivative is explained as follows. The reaction between polyamine-ketimine derivatives and epoxy resins occurs very easily, but in this case the ketimine groups and, if the epoxy resin contains blocked isocyanate groups, the isocyanate groups are decomposed. It is necessary that the temperature is such that it does not occur, and it is preferably carried out at a temperature of 50 to 130°C. In this case, since heat is generated, it is preferable to carry out the reaction in the presence of an organic solvent. As the organic solvent, for example, the above-mentioned ketone is suitably used, but other hydrophilic solvents such as ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, and ethylene glycol monoethyl ether acetate can also be used. The product obtained by the reaction of a polyamine-ketimine derivative and an epoxy resin contains, in one molecule,
at least two tertiary amino groups and at least two
The ketimine group is decomposed into a primary amino group and a ketone by adding at least an amount of water equivalent to the ketimine group to the product. In one molecule obtained here, the reaction product having at least two tertiary amino groups and at least two primary amino groups and glycidol are added to the primary amino group of the reaction product. An amino group-containing resin can be obtained by reacting glycidol at a ratio of 0.2 to 2.0 mol, preferably 0.5 to 1.5 mol, per 1.0 mol. The glycidol used here is a monoepoxy compound represented by the following structural formula,
Commercially available products include, for example, Epiol OH manufactured by NOF Corporation. Structural formula If glycidol is less than 0.2 mol per 1.0 mol of primary amino groups in the above reaction product,
Since fewer hydroxyl groups are introduced into the molecular ends of the resulting amino group-containing resin and more primary amino groups remain, the PH of the electrodeposition paint becomes higher, but the rust prevention ability of the resulting paint film decreases. If it exceeds 2.0 mol, the basicity of the amino group decreases, making it difficult to obtain an electrodeposition paint with a high pH. The reaction between glycidol and primary amino groups occurs very easily, but if necessary, under heating, especially at 50°C.
Preferably it is carried out at ~130°C. In that case, in order to avoid heat generation, glycidol may be added dropwise into the organic solvent solution of the reaction product over 0.5 to 2.0 hours to cause the reaction. The obtained amino group-containing resin is at least partially neutralized with an acid to make it water-soluble or water-dispersible, but it may also be used alone as an electrodeposition coating, or it may contain other amino groups in its molecules. You may use a mixture of one or more resins having amino groups (hereinafter referred to as resins having amino groups). Here, the amino group-containing resin is, for example, a bisphenol A/epichlorohydrin condensation product, or this condensation product containing a hydroxyl group, a carboxyl group, a thiol group, a primary amino group, a secondary amino group, etc. Among the compounds, examples include resins having amino groups obtained by reacting monoalkanolamines or dialkanolamines with epoxy resins having epoxy groups at the ends of the molecules obtained by extending the molecular chain. The mixing ratio of the amino group-containing resin and the amino group-owning resin is such that the pH of the resulting cationic electrodeposition paint is 6.0.
Any of the above can be selected. The composition for cationic electrodeposition coatings of the present invention contains an amino group-containing resin as an essential component, and optionally contains an amino group-containing resin. It can also contain organic polyisocyanates that are completely blocked with a curing agent and resins that have hydroxyl groups that can react with isocyanate groups and that do not have groups that are substantially neutralized by acids. . Here, examples of the organic polyisocyanate and blocking agent include aromatic or aliphatic diisocyanates mentioned above for the partially blocked organic polyisocyanate, adducts of these with polyols, and blocking agents. Medicines can be given. There is no particular critical content of the completely blocked organic polyisocyanate in the cationic electrodeposition coating composition of the present invention, but it may be added to the amino group-containing resin and the amino group-containing resin used as necessary. has previously reacted with a partially blocked organic polyisocyanate and contains blocked isocyanate groups,
It is preferable that the amount of isocyanate groups including the isocyanate groups does not exceed the total amount of hydroxyl groups that can react with isocyanate groups, and in particular, the total number of moles of blocked isocyanate groups and the total number of moles of hydroxyl groups The ratio of
A range of 0.1:1.0 to 1.0:1.0 is preferred. The total number of moles of blocked isocyanate groups is
If it is less than 0.1, cross-linking is insufficient, and the resulting coating film will not have sufficient rust prevention or other physical properties, and if it exceeds 1.0, some of the isocyanate groups will participate in cross-linking. The anti-corrosive properties and other physical properties of the resulting coating film are deteriorated, as it remains as a substantially uncrosslinked portion. Examples of resins that have hydroxyl groups that can react with isocyanate groups and that do not have groups that can be substantially neutralized by acids include alkyl etherified melamine resins, alkyl etherified urea resins, and alkyl etherified urea resins. Alkyl etherified amino resins such as etherified benzoguanamine resins; phenolic resins; polyvinyl alcohol;
Polyvinyl butyral resins; polyethers such as polyethylene glycol and polypropylene glycol; epoxy resins and phenoxy resins such as bisphenol A/epichlorohydrin condensation products;
Examples include polyester polyols such as polycaprolactone; polyolefin diols such as prebutadiene having a hydroxyl group at the end; any of these can be used as long as they do not impair the purpose of the present invention; It is preferable not to exceed 20 parts by weight. The composition for cationic electrodeposition coating of the present invention obtained as described above is obtained by neutralizing the amino groups of the amino group-containing resin and the amino groups of the amino group-possessing resin used as necessary with an acid. Therefore, it can be water-soluble or water-dispersible. Here, acids include carboxylic acids such as formic acid, acetic acid, propionic acid, and butyric acid; oxycarboxylic acids such as glycolic acid and lactic acid; carboxylic acids having unsaturated groups such as acrylic acid and methacrylic acid; thioglycolic acid; Examples include acids. The amount of acid used must be at least sufficient to make the cationic electrodeposition coating composition of the present invention water-dispersible, but it must be within the range that the pH of the resulting cationic electrodeposition coating does not become less than 6.0. selected.
Typically, neutralization rates are achieved in the range of 10-60%. The neutralized cationic electrodeposition coating composition obtained as described above is prepared by adding 1 to
The resin is dissolved, emulsified, or dispersed to a resin concentration of 30% by weight, preferably 5 to 25% by weight. In that case, hydrophilic coupling solvents, surfactants, surface conditioners, antioxidants, etc. commonly used in the field of cationic electrodeposition coating technology may be included, if necessary. A catalyst may also be included to aid in decomposition of blocked isocyanate groups and reaction with hydroxyl groups. Examples of the catalysts used include metal salts of organic acids such as lead octylate, lead naphthenate, zinc naphthenate, dibutyltin dilaurate, and dibutyltin oxide, and organic metal compounds. Although it is of course possible to use the composition for cationic electrodeposition paint of the present invention as it is without containing any pigment, it may also be used with pigments commonly used in the field of cationic electrodeposition paints, such as iron oxide, lead oxide, They can include strontium chromate, carbon black, titanium dioxide, cadmium yellow, cadmium red, yellow lead, talc, barium sulfate, and the like. To electrocoat an electrodeposition paint made of the cationic electrodeposition paint composition of the present invention, the object to be coated is used as a cathode and immersed in the electrodeposition paint, as in the case of conventional cationic electrodeposition paints. Then apply a voltage of 50 to 500V and 0.5
Apply electricity for ~5 minutes. Next, if necessary, excess paint adhering to the object to be coated is removed by washing with water, and then heated with a commonly used heating device such as a hot air baking oven or an infrared heating lamp to form a cured coating film. The heating conditions may depend on the dissociation temperature of the blocking agent of the blocked organic polyisocyanate used, and are therefore 120-250 DEG C. for 1-60 minutes. Hereinafter, the present invention will be explained in more detail with reference to Examples and Comparative Examples. In the examples, parts are parts by weight, and % is % by weight. Example 1 (1) Synthesis of polyamine-ketimine derivative Monomethylamine propylamine 880.0 parts Methyl isobutyl ketone 1202.0 A mixture of the above composition was put into a reactor equipped with a stirrer, a cooling tube, a distilled water separator, and a thermometer. The mixture was heated with stirring (approximately 100 to 110°C), and the temperature was gradually increased to a state of gentle reflux at approximately 130°C. about
The reaction was continued at 130°C for about 11 hours to obtain 340 parts of distilled water, which was then cooled to 40°C to obtain a polyamine-ketimine derivative solution (non-volatile content: 88%). (2) Synthesis of amino group-containing resin Epoxy resin (Epicote 1004 manufactured by Yuka Ciel Epoxy Co., Ltd., bisphenol A/epichlorohydrin condensation epoxy resin, molecular weight approximately 1800, epoxy equivalent approximately 900) 777.0 parts Methyl isobutyl ketone 429.0 Polyamine-ketimine derivative solution of (1) above
167.0〃 Deionized water 45.0〃 Glycidol 4 (manufactured by NOF Corporation, Epiol
OH) 65.0〃 Ethylene glycol monobutyl ether
200.0 Based on the above formulation, the following procedure was carried out. Epoxy resin and methyl isobutyl ketone were charged into a reactor equipped with a stirrer, a cooling tube, a thermometer, and a dropping tank, and heated and stirred (at about 90° C.) to obtain an epoxy resin solution. After the temperature of the obtained epoxy resin solution was raised to 80°C, the polyamine-ketimine derivative solution of (1) above was added and reacted at 80 to 100°C for 2 hours. Then, after adding deionized water, glycidol was added dropwise over 1 hour while keeping the temperature at 100°C. Next, the temperature was raised to 110 to 120°C, and the reaction was continued for 2 hours, and then the temperature was raised to 130 to 140°C, and a portion of the methyl isobutyl ketone was distilled off under reduced pressure. Then,
Add ethylene glycol monobutyl ether to make a yellow transparent amino group-containing resin solution (non-volatile content: 68
%) was obtained. (3) Synthesis of partially blocked organic polyisocyanate Tolylene diisocyanate 514.0 parts Methyl isobutyl ketone 130.0 2-ethylhexyl alcohol 356.0 Based on the above formulation, the following procedure was carried out. Tolylene diisocyanate and methyl isobutyl ketone were charged into a reactor equipped with a stirrer, a cooling tube, a thermometer, and a dropping tank, and the mixture was heated to 50°C while stirring. While keeping the temperature at 50°C, 2-ethylhexyl alcohol was added dropwise from the dropping tank over 5 hours, and the reaction was continued for an additional hour to remove the partially blocked organic polyisocyanate solution (non-volatile content).
87%). (4) Synthesis of amino group-containing resin Epoxy resin (as above) 900.0 parts Methyl isobutyl ketone 400.0 Partially blocked organic polyisocyanate solution (as above) 329.0〃 Diethanolamine 210.0〃 Ethylene glycol monobutyl ether
232.0 Based on the above formulation, the following procedure was carried out. Epoxy resin and methyl isobutyl ketone were charged into a reactor equipped with a stirrer, a thermometer, and a cooler, and heated (about 90°C) to obtain an epoxy resin solution. A partially blocked organic polyisocyanate solution was added to the resulting epoxy resin solution, and
The reaction was carried out at ℃ for 2 hours. Next, diethanolate amine was added and the mixture was reacted at 90 to 110°C for 2 hours, then the temperature was raised to 120 to 130°C, and part of the methyl isobutyl ketone was distilled off under reduced pressure. Then, ethylene glycol monobutyl ether was added to obtain an amino group-containing resin solution (70% non-volatile content). (5) Preparation of pigment-free cationic electrodeposition paint 500.0 parts of the amino group-containing resin solution of (2) above 500.0 parts of the amino group-containing resin solution of (4) above 500.0〃 Acetic acid 20.0〃 Deionized water 3650.0〃 Based on the above formulation , I did it as follows. The amino group-containing resin of (2) above and the amino group-containing resin of (4) above were mixed. Next, acetic acid was added to make the neutralization rate 40%, and while stirring the resin mixture, deionized water was gradually added to give a bluish-white color.
A cationic electrodeposition paint containing no pigment was obtained. The pH of the obtained cationic electrodeposition paint was 6.6. (6) Electrodeposition coating Bonderite is added to the cationic electrodeposition paint in (5) above.
A steel plate treated with 3118 (zinc phosphate base treatment agent, manufactured by Nippon Parkerizing Co., Ltd.) was immersed as a cathode,
Electrodeposition paint was applied by applying a voltage of 240V for 3 minutes. Then, it was washed with water to remove excess pigment, and baked in a hot air drying oven at 170°C for 25 minutes to obtain a smooth and hard coating film (dry film thickness: 18 μm). The obtained coating film was cut into a length of about 10 mm using a cutter knife according to JIS K5400 (1979), 7.8 Salt spray test method.
A scratch was made reaching the base of two intersecting strips of cm, a corrosion resistance test was conducted using a salt spray tester, and after a predetermined period of time, cellophane tape was applied and peeled off, and the width of the coating film that was peeled off along with the cellophane tape was measured. However,
As shown in Table 1, it exhibited extremely excellent antirust ability. Example 2 (1) Preparation of cationic electrodeposition paint containing pigment Amino group-containing resin solution of Example 1 (2) 100.0 parts Acetic acid 4.2〃 Ethylene glycol monobutyl ether 20.2 parts Kaolin 100.0〃 Carbon black 30.0〃 Based on the above formulation , I did it as follows. Each of the above components was placed in an attritor and dispersed for 10 hours to obtain a pigment paste. To 254 parts of the obtained pigment paste, 4200 parts of the pigment-free cationic electrodeposition paint of Example 1 (5) was gradually added with stirring. Then, deionized water was added to obtain a cationic electrodeposition paint (solid content: 13%) containing pigment. The pH of the obtained cationic electrodeposition paint was 6.8. (2) Electrodeposition coating The cationic electrodeposition paint from (1) above was electrocoated in the same manner as in Example 1, washed with water, and baked.
A smooth and hard coating film (dry film thickness 22μ) was obtained. The corrosion resistance of the resulting coating film was tested in the same manner as in Example 1, and as shown in Table 1, it showed extremely excellent antirust ability. Example 3 (1) Synthesis of amino group-containing resin Epoxy resin (Epicote 1007 manufactured by Yuka Ciel Epoxy Co., Ltd., bisphenol A/epichlorohydrin condensation epoxy resin, molecular weight approximately 4200, epoxy equivalent approximately 2100) 2100.0 parts Methyl isobutyl Ketone 1050.0〃 Polyamine-ketimine derivative solution (Epocure H-1 manufactured by Yuka Ciel Epoxy Co., Ltd., ketimine derivative solution of diethylenetriamine, non-volatile content 38%)
267.0〃 Deionized water 288.0〃 Glycidol [above - Example 1 (2)] 296.0〃 Ethylene glycol monobutyl ether
530.0 parts Based on the above formulation, a transparent yellow-added amino group-containing resin solution (non-volatile content: 68%) was obtained in the same manner as in Example 1 (2). (2) Preparation of cationic electrodeposition paint containing pigment 300.0 parts of the amino group-containing resin solution of (1) above 700.0 parts of the amino group-containing resin solution of Example 1 (4) 700.0 parts of polycaprolactone triol (manufactured by Daicel Chemical Industries, Ltd.) Plaxel P-308) 35.0〃 Completely blocked organic polyisocyanate solution (DC-2969 manufactured by Nippon Polyurethane Co., Ltd., ε-caprolactam blocked product of hexamethylene diisocyanate-based organic polyisocyanate, non-volatile content 80%) 18.0〃 Acetic acid 12.5 parts deionized water 192.05 Based on the above formulation, the following procedure was carried out. The amino group-containing resin solution of (1) above, the amino group-containing resin solution of Example 1 (4), polycaprolactone triol, and a completely blocked organic polyisocyanate solution were mixed. Next, acetic acid was added to make the neutralization rate 40%, and deionized water was gradually added to the resin mixture while stirring to obtain a blue-white clear base (non-volatile content 25%). Next, 2520 parts of the above clear base was gradually added to 254 parts of the pigment base in Example 2 (1) while stirring. Then, deionized water was added to obtain a cationic electrodeposition paint (solid content: 13%) containing pigment. The pH of the obtained cationic electrodeposition paint was 6.5. (3) Electrodeposition coating The cationic electrodeposition paint from (2) above was electrocoated in the same manner as in Example 1, washed with water, and baked.
A smooth and hard coating film (dry film thickness 18μ) was obtained. The corrosion resistance of the resulting coating film was tested in the same manner as in Example 1, and as shown in Table 1, it showed extremely excellent antirust ability. Comparative Example 1 Epoxy resin [Previous Example 1 (2)] 776.5 parts Methyl isobutyl ketone 428.6 Polyamine-ketimine derivative solution of Example 1 (1)
173.4 Ethylene glycol monobutyl ether
200.0 A resin containing an amino group, which has a ketimine group at the end and generates a primary amino group when it comes into contact with water, was synthesized as follows. Put epoxy resin and methyl isobutyl ketone into a reactor equipped with a stirrer, cooling tube, and thermometer.
An epoxy resin solution was obtained by heating (approximately 90°C) and stirring. After the obtained epoxy resin solution was heated to 80℃,
After adding the polyamine-ketimine derivative solution of Example 1 (1) and reacting at 80 to 100°C for 2 hours,
The temperature was raised to 140°C, and a portion of methyl isobutyl ketone was distilled off under reduced pressure. Then, ethylene glycol monobutyl ether was added to obtain a resin solution containing amino groups (70% nonvolatile content). The procedure was the same as in Example 1 (5), except that the obtained amino group-containing resin solution was replaced with the amino group-containing resin used in Example 1 (5) for the preparation of a cationic electrodeposition paint containing no pigment. A cationic electrodeposition paint containing no pigment was obtained. PH of the obtained cationic electrodeposition paint
was 6.3. The obtained cationic electrodeposition paint was electrodeposited in the same manner as in Example 1, washed with water, and baked.
A hard but uneven coating film (dry film thickness 20μ) was obtained. When the corrosion resistance of the obtained coating film was tested in the same manner as in Example 1, as shown in Table 1, the antirust ability was extremely poor. Comparative Example 2 Amino group-possessing resin solution of Example 1 (4) 1000.0 parts Acetic acid 10.8 Deionized water 4370.0 With the above formulation, a pigment-free cationic electrodeposition paint was prepared as follows. Acetic acid was added to the amino group-possessing resin solution of Example 1 (4) to make the neutralization rate 40%, and then deionized water was gradually added to the resin solution while stirring to produce a pigment that exhibits a bluish-white color. A cationic electrodeposition paint containing no ion was obtained. The pH of the obtained cationic electrodeposition paint was extremely low at 4.2. The obtained cationic electrodeposition paint was electrodeposited in the same manner as in Example 1, washed with water, and baked.
A smooth and hard coating film (dry film thickness 18μ) was obtained. When the corrosion resistance of the obtained coating film was tested in the same manner as in Example 1, as shown in Table 1, the rust prevention ability was poor. 【table】

Claims (1)

[Claims] 1 A product obtained by reacting an epoxy resin having at least two epoxy groups in one molecule with a polyamine-ketimine derivative having one secondary amino group and at least one ketimine group in one molecule A reaction product having at least two tertiary amino groups and at least two primary amino groups in one molecule obtained by decomposing the ketimine group of Glycidol per 1.0 mole of primary amino group
1. A composition for cationic electrodeposition coating, comprising an amino group-containing resin obtained by reaction in a proportion of 0.2 to 2.0 moles.