JPH06200194A - Composition for cationic electrodeposition coating - Google Patents

Abstract

PURPOSE:To provide the subject composition containing as a main component a composition comprising a specific resin, a specific epoxy resin and an imidazole compound, etc., excellent in bath stability, corrosion resistance and weatherability without using a poisonous lead compound, and useful for automotive bodies, etc. CONSTITUTION:The objective composition contains as a main compound a composition comprising (A) a resin having a hydroxy group and a cationic group, (B) an epoxy resin having on the average two or more of epoxy group- containing functional groups in the molecule, each of the functional groups having a structure in which the epoxy group is directly bonded to an alicyclic skeleton and/or a bridge-having alicyclic skeleton, and (C) one or more components selected from imidazole compounds, benzotriazole compounds and their reaction products with an epoxy resin, and preferably (D) an inorganic bismuth compound. The solid content weight ratio of the component B to the component A is preferably 0.25-0.65, and the amount of the component C is preferably 1-15wt.% based on the total amount of the components A and B.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a cationic electrodeposition coating composition which is excellent in bath stability, forms a coating film having good curability, corrosion resistance and weather resistance, and does not require the use of toxic lead compounds. It relates to a composition.

[0002]

2. Description of the Related Art Conventionally, a resin composition containing a polyamine resin such as an amine-added epoxy resin and a block polyisocyanate compound as main components has excellent corrosion resistance and is widely used in cationic electrodeposition paints. There is. However, the composition has various drawbacks as listed below, and it is strongly desired to eliminate them.

When heated at a high temperature, the block polyisocyanate compound is thermally decomposed to generate tars and soot,
Moreover, the top coating film turns yellow, causes bleeding and curing failure, and also has reduced weather resistance, and the coated surface is liable to whiten.

If an organotin compound is added as a catalyst in order to lower the curing start temperature of the coating film, the exhaust combustion catalyst may be poisoned.

When a large amount of a lead compound is blended as a catalyst for accelerating the curing of a coating film or for anticorrosive property, it is necessary to take the utmost care in handling and safety and hygiene, and it is not preferable in terms of pollution prevention.

For the purpose of eliminating the above-mentioned and disadvantages,
The applicant has previously used a resin having a hydroxyl group and a cationic group as a base resin, and having an epoxy group-containing functional group having a structure in which an epoxy group is bonded to an alicyclic skeleton and / or a bridged alicyclic skeleton. A resin composition for a cationic electrodeposition coating using an epoxy resin as a curing agent has been proposed (JP-A-2-2).
55874 publication). However, in order to accelerate the curing reaction between the resin having a hydroxyl group and a cationic group as the base resin and the epoxy resin having the epoxy group-containing functional group as the curing agent, the lead compound still has to be used. It has never been possible to completely eliminate the drawbacks of.

[0007]

The present inventors have a resin (base resin) having a hydroxyl group and a cationic group and a structure in which an epoxy group is bonded to an alicyclic skeleton and / or a bridged alicyclic skeleton. For the purpose of eliminating the above-mentioned drawbacks in the cationic electrodeposition coating composition containing an epoxy resin (curing agent) having an epoxy group-containing functional group as a main component, a lead compound is not used, and a case where the lead compound is used is used. The inventors have earnestly conducted research on a catalyst which exhibits the same or higher curability and anticorrosion property and has no problem in safety and hygiene and pollution control. As a result, this time, as the curing catalyst, at least one selected from an imidazole compound, a benzotriazole compound, and a reaction product of these with an epoxy resin.
The inventors have found that the use of seeds can achieve the object, and completed the present invention.

Thus, the present invention provides (A) a resin having a hydroxyl group and a cationic group [component (A)], (B).
An epoxy resin [component (B)] having an average of two or more epoxy group-containing functional groups having a structure in which an epoxy group is directly bonded to an alicyclic skeleton and / or a bridged alicyclic skeleton, per molecule.
And (C) at least one component [(C) component] selected from an imidazole compound, a benzotriazole compound, and a reaction product of these with an epoxy resin, and, if necessary, (D) an inorganic bismuth compound [( The present invention provides a cationic electrodeposition coating composition, which comprises a composition consisting of D) as a main component.

Hereinafter, each component used in the present invention will be described in more detail. Since the components (A) and (B) are described in detail in JP-A-2-255874 by the present applicant, (A) Regarding the components) and (B), the description of the publication is incorporated by reference, and the outline thereof will be described only in this specification.

Component (A): The base resin having a hydroxyl group and a cationic group as the component (A) contains a hydroxyl group capable of reacting with the epoxy group in the component (B) described later and has a stable aqueous dispersion. Any resin having a sufficient number of cationic groups to form a product is included. Then, examples of the resin as the component (A) include the following.

(I) a reaction product obtained by reacting a polyepoxy resin with a cationizing agent; (ii) a polycondensate of a polycarboxylic acid and a polyamine (see US Pat. No. 2,450,940). ) Is protonated with an acid; (iii) A polyaddition product of a polyisocyanate and a polyol with a mono- or polyamine is protonated with an acid; (iv) Copolymerization of an acrylic or vinyl monomer containing a hydroxyl group and an amino group. Those obtained by protonating the coalescence with acid (Japanese Patent Publication No. 45-12395, Japanese Patent Publication No. 45-123).
96); (v) Protonated with an acid an adduct of a polycarboxylic acid resin and an alkyleneimine (US Pat. No. 3,403,
No. 088); etc.

Specific examples and manufacturing methods of these cationic resins are described in, for example, Japanese Patent Publication No. 45-12395, Japanese Patent Publication No. 45-12396, and Japanese Patent Publication No. 49-23.
087, U.S. Pat. No. 2,450,940,
U.S. Pat. No. 3,403,088, U.S. Pat.
891,529, U.S. Pat. No. 3,963,663.
Since it is described in the specification, etc., the detailed description will be replaced with these citations.

What is particularly desirable as the component (A) in the present invention is that a cationizing agent is added to the epoxy group of the polyepoxide compound which is contained in the above (i) and which is obtained from the polyphenol compound and epichlorohydrin and has excellent corrosion resistance. It is a reactive product obtained by reaction.

The polyepoxide compound is a compound having two or more epoxy groups in one molecule, and generally has a number average molecular weight in the range of at least 200, preferably 400 to 4,000, more preferably 800 to 2,000. Those having is suitable. As such a polyepoxide compound, those known per se can be used, and examples thereof include a polyglycidyl ether of a polyphenol compound which can be produced by reacting a polyphenol compound with epichlorohydrin in the presence of an alkali. To be done.

Among the above polyepoxide compounds, (A)
Particularly suitable for preparing the components are those having a number average molecular weight of at least about 380, more preferably about 800 to about 2,000.
0 and epoxy equivalents of polyglycidyl ethers of polyphenol compounds in the range of 190 to 2,000, preferably 400 to 1,000.

On the other hand, as a cationizing agent for introducing a cationic group into the above polyepoxide compound, an aliphatic, alicyclic or aromatic-aliphatic primary or secondary amine, a tertiary amine salt, Examples thereof include secondary sulfide salts and tertiary phosphine salts. These react with the epoxy groups of the polyepoxide compound to form cationic groups.

Examples of the amine compound in the cationizing agent include the following.

(1) Methylamine, ethylamine, n
-Or a primary amine such as iso-propylamine, monoethanolamine, n- or iso-propanolamine; (2) diethylamine, diethanolamine, di-n-
Or secondary amines such as iso-propanolamine, N-methylethanolamine, N-ethylethanolamine; (3) ethylenediamine, diethylenetriamine, hydroxyethylaminoethylamine, ethylaminoethylamine, methylaminopropylamine, dimethylaminoethylamine, dimethyl. Polyamines such as aminopropylamine.

Of these, alkanolamines having a hydroxyl group are preferable. Alternatively, the primary amino group may be reacted with a ketone in advance and blocked, and then the remaining active hydrogen may be reacted with the epoxy group.

Further, in addition to the above amine compounds, basic compounds such as ammonia, hydroxylamine, hydrazine, hydroxyethylhydrazine and N-hydroxyethylimidazoline compounds can be similarly used.
The basic group formed using these compounds can be protonated with an acid, particularly preferably a water-soluble organic carboxylic acid such as formic acid, acetic acid, glycolic acid or lactic acid to form a cationic group.

Further, tertiary amines such as triethylamine, triethanolamine, N, N-dimethylethanolamine, N-methyldiethanolamine, N, N-diethylethanolamine and N-ethyldiethanolamine can also be used, and these are acid. Can be protonated in advance and then reacted with an epoxy group to form a quaternary salt.

The hydroxyl group in the component (A) used in the present invention is, for example, an alkanolamine in the above cationizing agent, a caprolactone ring-opened product which may be introduced into an epoxide compound, a polyol or the like. First
Secondary hydroxyl group: secondary hydroxyl group in epoxy resin and the like can be mentioned. Of these, the primary hydroxyl group introduced by the alkanolamine is preferable because it has excellent crosslinking and curing reactivity with the component (B). Such alkanolamines are preferably those exemplified as the cationizing agent.

The content of hydroxyl groups in the component (A) is (B)
From the viewpoint of cross-linking and curing reactivity with the epoxy group contained in the component, the hydroxyl equivalent is 20 to 5,000, particularly 100 to 1,
It is preferably in the range of 000, and particularly the primary hydroxyl group equivalent is 2
It is preferably in the range of 00 to 1,000.

The content of the cationic group in the component (A) is preferably at least the minimum necessary to stably disperse the component (A), and converted into KOH (mg / g solid content) (amine value). In general, it is preferably in the range of 3 to 200, particularly 10 to 80. However, even when the content of the cationic group is 3 or less, it is possible to disperse the aqueous solution by using a surfactant or the like. In this case,
The pH of the aqueous dispersion composition is usually 4 to 9, more preferably 6
It is desirable to adjust the cationic group so that it is ˜7.

The component (A) used in the present invention has a hydroxyl group and a cationic group, and in principle, it is desirable not to include a free epoxy group.

Component (B): a curing agent capable of forming a crosslinked cured coating film mainly by an etherification reaction with the base resin of the above-mentioned component (A), which is an alicyclic skeleton and / or a bridged fat. An average of 2 or more, and preferably 3 or more, epoxy group-containing functional groups having a structure in which an epoxy group is directly bonded to a cyclic skeleton are included in one molecule.

The epoxy group-containing functional group in the component (B) is composed of an alicyclic skeleton and / or a bridged alicyclic skeleton and an epoxy group, and the alicyclic skeleton has 4 to 10 members, preferably 5 members. A 6-membered saturated carbocyclic ring or a condensed ring in which two or more of these rings are condensed, and the bridged alicyclic skeleton has two carbon atoms constituting the above-mentioned monocyclic or polycyclic ring. A linear or branched C _1-6 (preferably C _1-4 ) alkylene group between [eg, —CH ₂ —, —CH ₂ CH ₂ —, —CH
_{(CH 3) -, - CH} 2 (CH 3) CH 2 -, - C (CH 3) 2 -,
-CH (C ₂ H ₅ ) CH _2-, etc.] bridge (endmethylene,
End ethylene and the like) are those containing a ring bonded thereto.

On the other hand, epoxy group

[0029]

[Chemical 1]

Is one of the carbon atoms in the epoxy group directly bonded to a ring carbon atom in the alicyclic skeleton or the bridged alicyclic skeleton [for example, the following formulas (I) and (II)] Or the two carbon atoms of the epoxy group and two adjacent carbon atoms constituting the ring in the alicyclic skeleton or the bridged alicyclic skeleton are common [eg, the following formula: (I
II), (IV)] is important. Specific examples of such an epoxy group-containing functional group include those represented by the following formulas (I) to (IV).

[0031]

[Chemical 2]

In the formula, R ₁ , R ₂ , R ₃ , R ₅ , R ₆ , R ₇ and R
₁₀ and R ₁₁ each represent H, CH ₃ or C ₂ H ₅ , and R ₄ , R ₈ and R ₉ each represent H or CH ₃ .

The component (B) used in the present invention has an average of at least 2, preferably 3 or more, and more preferably 4 epoxy-containing functional groups selected from the above formulas (I) to (IV) per molecule. You can have more than one.

Of the above, the epoxy group-containing groups represented by the formulas (I) and (III) are preferable, and particularly the following formula (V):

[0035]

[Chemical 3]

An epoxy group-containing functional group represented by, and the following formula (VI)

[0037]

[Chemical 4]

Epoxy group-containing functional groups represented by are preferred.

The epoxy equivalent and molecular weight of the component (B) used in the present invention are not strictly limited, and can be changed according to the production method thereof, the intended use of the final resin composition, etc. Speaking specifically, the epoxy equivalent is usually 100 to 2,000, preferably 150 to 500,
More preferably, it can be in the range of 150 to 250, and the number average molecular weight is usually 400 to 100,00.
Suitably, it is in the range of 0, preferably 700 to 50,000, more preferably 700 to 30,000.

The epoxy resin [component (B)] having two or more such epoxy group-containing functional groups in one molecule is described, for example, in JP-B-56-8016 and JP-A-57-47.
365, JP-A-60-166675, JP-A-63-221121, and JP-A-63-23402.
It is described in documents such as Japanese Patent Publication No. 8 and can be used those known per se.

Alternatively, the component (B) having an epoxy group-containing functional group is obtained by a method known per se, and the main production methods thereof are listed below, but the invention is not limited thereto. .

First Production Method: Part of the double bond of the alicyclic compound having two or more carbon-carbon double bonds in one molecule is partially epoxidized, and the epoxy group is subjected to ring-opening polymerization, A method of epoxidizing the double bond remaining in a polymer. Second production method: a method of ring-opening polymerization of an alicyclic compound having two or more epoxy groups in the same molecule based on the epoxy groups to such an extent that all of the epoxy groups are not erased.

Third production method: a method of polymerizing a compound having an epoxy group-containing functional group and a polymerizable unsaturated bond in the same molecule.

The details of these manufacturing methods are described in the above-mentioned Japanese Patent Laid-Open No. 2-255874, so that the detailed description will be replaced with the citation.

The above-mentioned component (B) is suitable for applications requiring a high level of performance such as cationic electrodeposition coatings used for automobile bodies, in which an epoxy group-containing functional group is contained per molecule. It has 3 or more on average, more preferably 4 or more on average, most preferably 5 or more on average, and the epoxy equivalent is preferably 1 or more.
In the range of from 0 to 2,000, more preferably from 150 to 500, especially from 150 to 250, and the number average molecular weight is preferably from 400 to 100,000, more preferably from 700 to 50,000, particularly preferably from 700 to 30,0
It is in the range of 00.

The amount of the component (B) used depends on the type of the component (A) used, and does not impair the stability of the cationic electrodeposition coating composition or the minimum amount necessary for the coating film obtained to be thermoset. It can be appropriately changed within the range of the maximum amount, but generally, the weight ratio of the solid content to the component (A) of the component (B) (B)
It is preferable to select / (A) so as to be in the range of 0.2 to 1.0, particularly 0.25 to 0.85, and more preferably 0.25 to 0.65.

The composition of the present invention may contain the component (B) partially added to the component (A) in advance.

Component (C) : A catalyst for accelerating the cross-linking and curing reaction between the above-mentioned (A) component and (B) component, which comprises an imidazole compound, a benzotriazole compound and a reaction product of these with an epoxy resin. At least one ingredient selected.

Examples of the above-mentioned imidazole compound include those represented by the following formula:

[0050]

[Chemical 5]

In the formula, R ₁₃ is a linear or branched C
₁ to ₂₅ (preferably C ₁ to ₁₇ ) alkyl group or aryl group (particularly phenyl group), wherein R ₁₄ and R ₁₅ are each a lower alkyl group optionally substituted with a hydrogen atom, a hydroxyl group or a nitrile group ( For example, methyl, hydroxymethyl, 2-cyanoethyl group, etc.) or aralkyl group (for example, benzyl group), and R ₁₆ represents a hydrogen atom or a lower alkyl group optionally substituted with a hydroxyl group (for example, hydroxymethyl group, Specifically, for example, they are commercially available from Shikoku Chemicals Co., Ltd. under the trade name of series such as Curesol OR, Curesol CN, Curesol CNS, Curesol AZINE, Curesol OK, and Curesol HZ. The following are mentioned as particularly preferable ones. (The figures in parentheses are Shikoku Chemicals Co., Ltd.)
Is the product name).

[0052]

[Chemical 6]

[0053]

[Chemical 7]

[0054]

[Chemical 8]

Examples of the benzotriazole compound include those represented by the following formula

[0056]

[Chemical 9]

In the formula, R ₁₇ and R ₁₈ are each a hydrogen atom or a linear or branched C ₁ to ₁₀ (preferably C ₁ to
₆ ) represents an alkyl group, including those represented by
Particularly, 1,2,3-benzotriazole in which R ₁₇ and R ₁₈ are hydrogen atoms in the above formula (VIII) is preferable.

Further, in the above formula (VII), the imidazole compound in which R ₁₅ is a hydrogen atom and the above formula (V
In the benzotriazole compound of III), the active hydrogen of the secondary amino group thereof can react with the epoxy group of the epoxy resin to form an adduct, and such a reaction product is also the component (C) of the present invention. Can be used as

Examples of the epoxy resin capable of forming an adduct include bisphenol type, phenol novolak type, gresol novolak type and aliphatic type epoxy resins having at least one epoxy group in one molecule. Generally, those having a number average molecular weight in the range of about 300 to about 2,000 are suitable.

The reaction ratio of the epoxy resin to the imidazole compound or the benzotriazole compound is such that the epoxy resin of the latter is 0.3 per one of the former secondary amino groups.
It can be one.

As the component (C), the above-mentioned imidazole compound, benzotriazole compound or a reaction product of these with an epoxy resin may be used alone or in combination of two or more kinds. The amount used can be varied over a wide range depending on the types of the components (A) and (B) and other conditions.
In the case of an imidazole compound and a benzotriazole compound, generally 0.1 to 10% by weight, particularly 0.2 to 5% by weight, and these and an epoxy based on the total amount of both components (A) and (B). In the case of a reaction product with a resin, a range of 0.3 to 30% by weight, particularly 1 to 15% by weight is suitable.

Component ( D) : The inorganic bismuth compound is not an essential component in the composition of the present invention, but is useful for further improving the corrosion resistance of the coating film formed from the composition of the present invention. Specific examples of the inorganic bismuth compound that can be used include basic bismuth carbonate, bismuth carbonate oxide, bismuth nitrate, bismuth nitrate hydroxide, basic bismuth nitrate, bismuth oxide, bismuth hydroxide and bismuth sulfate. Of these, bismuth hydroxide is particularly preferable. The blending amount of the component (D) is not strict and can be arbitrarily selected according to the purpose. Generally, the amount of the metal is 15% by weight based on the total weight of the components (A) and (B). % Or less, particularly preferably in the range of 1 to 10% by weight.

Cationic electrodeposition coating composition : The cationic electrodeposition coating composition of the present invention is, for example, the above-mentioned (A),
It can be prepared by using the components (B) and (C) as essential components, and optionally using the component (D), and dissolving or dispersing them in an aqueous medium.
More specifically, the components (A) and (B) are first mixed and then dispersed in an aqueous medium, and then the component (C) and, if necessary, the component (D), and further the carbon black. , Titanium white, color pigments such as red iron oxide, extender pigments such as clay and talc, and other additives (for example,
It can be produced by blending a dispersant, an anti-repellent agent, etc.).

The resin composition for cationic electrodeposition coating composition of the present invention can be subjected to cationic electrodeposition coating on a conductive substrate. The thickness of the coating film is not particularly limited, but in general,
The range of 3 to 200 μ is suitable based on the cured coating film,
The coating film is, for example, 70 to 250 ° C., preferably 120.
It can be heat-cured at a temperature between ℃ and 160 ℃.

Cationic electrodeposition coating of the cationic electrodeposition coating composition of the present invention can be carried out by a method known per se. For example, the solid content in the bath is adjusted to 5 to 40% by weight, preferably 10 to 25% by weight and the pH is adjusted to 5 to 8, preferably 5.5 to 7, and the bath temperature is set to 20 to 35%.
C, preferably 25 to 30 C; current density (DC current)
0.005 to ^{2 A} / cm ² , preferably 0.01 to 1 A /
cm ² ; voltage 10 to 500 V, preferably 100 to 30
0V; and energizing time 0.5 to 5 minutes, preferably 2 to
It can be performed under the condition of 3 minutes.

After the electrodeposition coating, the object to be coated is lifted from the electrodeposition bath and washed with water, and then the water contained in the electrodeposition coating film can be removed by a drying means such as hot air.

The electrodeposition coating film thus formed using the resin composition for cationic electrodeposition coating composition of the present invention can be cured by heating as described above.

Next, the present invention will be described more specifically with reference to examples. In the examples, "part" is "part by weight" and "%" is "% by weight".

[0069]

EXAMPLES Example 1 Bisphenol A type epoxy resin having an epoxy equivalent of 950 [trade name "Epicoat 1004", Shell Chemical Co., Ltd.
Made] 1900 parts dissolved in 993 parts butyl cellosolve,
Then 210 parts of diethanolamine at 80 to 100 ° C
After dropping at 100 ° C. for 2 hours, the resin (A- having a solid content of 68%, a primary hydroxyl group equivalent of 528, and an amine value of 53 (A-
1) was obtained.

110 parts of this resin (A-1) (solid content 75
Part), EHPE3150 (trade name, manufactured by Daicel Chemical Industries, Ltd., having a cyclohexane skeleton using 4-vinylcyclohexene-1-oxide, epoxy resin, epoxy equivalent 175 to 195) as a curing agent (component B))
31% of 80% butyl cellosolve solution (solid content 25 parts)
Was blended to obtain a mixture (AB).

On the other hand, 14.8 parts of the above resin (A-1)
4.4 parts of 0% formic acid aqueous solution was added, and 15 parts of deionized water was added while stirring. Further, 20 parts of titanium white, 1 part of carbon black, 4 parts of Curezol C11Z (manufactured by Shikoku Chemicals Co., Ltd.) and 5 parts of bismuth hydroxide (purity 98%) were added, and the mixture was dispersed in a ball mill for 24 hours, followed by deionized water. By mixing, a pigment paste (P-1) having a solid content of 50% was obtained.

To 141 parts of the above (AB) mixture, 10%
12.0 parts of a formic acid aqueous solution was added, and deionized water was added while stirring to obtain 333 parts of emulsion having a solid content of 30%.
Then, to 333 parts of this emulsion, the amount (75.6 parts) of the pigment paste (P-1) shown in Table 2 below and deionized water were added to obtain a cationic electrodeposition coating composition having a solid content of 20%.

Examples 2 to 8 and Comparative Example 1 164 parts of Curezol 2MZ (manufactured by Shikoku Chemicals Co., Ltd.) was dissolved in 218 parts of methyl ethyl ketone, and the mixture was heated to 80 ° C. to obtain an epoxy resin [trade name: Epicoat 828, Shell Chemical Co., Ltd. ) Product] 380 parts was added dropwise over 1 hour and then at 80 ° C. for 2 hours.
The reaction product (E-1) was obtained by holding for a period of time.

1,2,3 to 148 parts of methyl ethyl ketone
-Benzotriazole [Product name CVI Chillest Co., Ltd.
Manufactured by 143 parts, and then heated to 85 ° C. to obtain an epoxy resin [trade name: Epicoat 828, manufactured by Shell Chemical Co., Ltd.] 22
After dropping 8 parts over 1 hour, it hold | maintained at 85 degreeC for 1 hour, and the reaction product (E-2) was obtained.

Instead of 4 parts of Curezol C11Z and 5 parts of bismuth hydroxide in the pigment paste (P-1) of the above Example 1, (C-1) and (E) are shown in Table 1 below.
Pigment pastes (P-2) to (P-
Using 8), a cationic electrodeposition coating composition having a solid content of 20% was obtained in the same manner as in Example 1. Table 2 shows the composition and blending amount of the electrodeposition coating composition.

The cationic electrodeposition coating composition thus obtained was used to adjust the bath temperature to 30 ° C.
Cation electrodeposition coating was performed by energizing at 0 to 300 V for 3 minutes, lifting from the bath, washing with water, and heating at 160 ° C. for 30 minutes to cure the coating film (film thickness 15 to 23 μm). The results of the performance test of the coating film are also shown in Table 2 below.

[0077]

[Table 1]

[0078]

[Table 2]

In Table 2, the coating composition of Comparative Example 1 is the pigment paste (P-1).
Instead of 1.8 parts of copper hydroxide, lead hydroxide (metal lead 90
%) 2.8 parts and no bismuth hydroxide was added and all were prepared as in Example 1 above.

Coating state: The coating state was visually evaluated. ◯ means good.

Curability: After wiping the coated surface 10 times with gauze soaked with methyl ethyl ketone, the degree of coloring of the gauze was observed. Those not markedly colored were marked with ◯.

Impact resistance: Using a DuPont type impact resistance tester, with the coated surface facing upwards, a 500 g impact point of 30 c
When the film was dropped from a height of m and the generation of cracks or peeling on the coating film could not be confirmed, it was evaluated as ◯.

SST resistance: This is a salt water spray resistance test, in which the coating film is cross-cut so as to reach the substrate, and this is tested according to JIS Z2371 (5% saline solution is sprayed at 35 ° C.) for 1000 hours. The creep width (one side) from the cross cut portion after the lapse of time was within 2 mm, which was defined as ◯.

Thread rust resistance: Cationic electrodeposition coating is performed as described above, and then an intermediate coating material (a known thermosetting intermediate coating material containing a polyester resin and a melamine resin as a main component) is applied (thickness: approx. 30μ), and after baking, a topcoat paint (a known thermosetting solid color topcoat paint containing acrylic resin and melamine resin as a main component) is applied (film thickness of about 40μ), and the coating film of the test plate is heat-cured. Then, the coating film was cross-cut so as to reach the substrate. This was subjected to a salt spray test for 24 hours under the same conditions as the above SST resistance, and then washed with deionized water.
It is placed in a container kept at a temperature of 40 ° C. and a relative humidity of 85%, and after 480 hours have passed, it is taken out and the length of the thread rust from the cut portion is measured to determine its maximum length.

Environmental pollution property: A paint containing a lead compound which is a heavy metal and may cause environmental pollution was marked with X, and a paint containing no lead compound was marked with ◯.

As is clear from the results of the performance tests of the above Examples and Comparative Examples, the cationic electrodeposition coating composition of the present invention is equivalent to that using a lead compound without using a toxic lead compound. It is a cationic electrodeposition paint that can form a coating film having higher performance and has less safety and health problems.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hiroshi Ichinose 4-17-1, Higashi-Hachiman, Hiratsuka-shi, Kanagawa Kansai Paint Co., Ltd. West Paint Co., Ltd.

Claims (2)

[Claims] 1. A resin having (A) a hydroxyl group and a cationic group, (B) one molecule of an epoxy group-containing functional group having a structure in which an epoxy group is directly bonded to an alicyclic skeleton and / or a bridged alicyclic skeleton. Containing as the main component a composition comprising an epoxy resin having an average of two or more per unit, and (C) at least one component selected from imidazole compounds, benzotriazole compounds and reaction products of these with epoxy resins. A cationic electrodeposition coating composition comprising: 2. A cationic electrodeposition coating composition containing the components (A), (B) and (C) according to claim 1 and a composition comprising (D) an inorganic bismuth compound as main components. Composition.