JPH07331181A - Coating composition - Google Patents

Abstract

PURPOSE:To obtain a cationic electrodeposition coating material which can give a coating film having a smooth surface and a large thickness by using a specified compound having at least two hydroxyl groups and at least two amide bonds and/ or at least two urethane bonds. CONSTITUTION:A compound (A) having at least two hydroxyl groups and at least two amide bonds and/or at least two urethane bonds in the molecule and having a molecular weight of 500 or above is made by introducing hydroxyl groups into a cyclic carbonate compound (B) or a cyclic ester compound (C) through its ring opening reaction. It is desirable that compound A is one which is formed by reacting amino groups with carboxyl groups and a lactone compound, in which the urethane bonds are formed by reacting amino groups with a cyclic carbonate compound, which is prepared by introducing hydroxyl groups thereinto through the ring opening of B or C and which has a molecular weight of 500-2000. Compound A is mixed with a cationic base resin (aminated hydroxy epoxy resin) and a curing agent to obtain a cationic electro-deposition coating material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating composition containing a compound useful for improving the coating surface smoothness and the electrodeposition coating film forming property, particularly a coating composition useful for cationic electrodeposition coating. Regarding

[0002]

2. Description of the Related Art Replenishment amount during electrodeposition coating is relatively small per unit time (that is, low turnover)
In order to prevent the film thickness from being reduced by cationic electrodeposition coating (formation of electrodeposition coating film) and to improve the smoothness of the coating surface, soft components and high boiling point solvents such as polyether polyol that give a plasticizing effect are used. It is compounded. However, even if such a component is added, the content of the organic solvent in the bath increases and the wastewater treatment load increases, and further the coating surface smoothness and the electrodeposition coating film forming property are not sufficiently improved, and the coating film It has been pointed out that there is a large amount of heat loss during baking and curing, and that coating film properties such as gloss, image clarity, and curability of the coated surface also deteriorate, and improvements in these are strongly desired.

[0003]

DISCLOSURE OF THE INVENTION The present invention is intended to eliminate the above-mentioned deficiencies, and is characterized in that, in place of the soft component, two or more hydroxyl groups and two or more amide bonds and / or Further, it was found that the object can be achieved by blending a compound having two or more urethane bonds and having the hydroxyl group formed by a ring-opening reaction of a cyclic carbonate compound or a cyclic ester compound, thereby completing the present invention. did.

That is, the present invention has two or more hydroxyl groups and two or more amide bonds and / or two or more urethane bonds in one molecule, and the hydroxyl groups are cyclic carbonate compounds or cyclic esters. A coating composition containing a compound having a molecular weight of 500 or more (hereinafter abbreviated as "compound A") produced by a ring-opening reaction of the compound, and a cationic electrodeposition coating composition containing the above compound Regarding

The compound A used in the present invention will be described. The compound A contains two or more hydroxyl groups in one molecule and 2
A compound having one or more amide bonds and / or two or more urethane bonds, and forming the hydroxyl group by a ring-opening reaction of a cyclic carbonate compound or a cyclic ester compound, and blending the compound. The coating surface smoothness and the electrodeposition coating film forming property can be remarkably improved.

In compound A, an amide bond is formed by the reaction of an amino group (-NH ₂ ) with a carboxyl group (-COOH) or a cyclic lactone compound, and a urethane bond is formed by the reaction of an amino group with a cyclic carbonate compound. It Further, the hydroxyl group is preferably generated by a ring-opening reaction of the cyclic ester compound or cyclic carbonate compound.

The compound A can be basically classified as follows. 1) Compound A-1: A compound having two or more hydroxyl groups and two or more amide bonds in one molecule, and two or more hydroxyl groups formed by a ring-opening reaction of a cyclic ester compound. 2) Compound A-2: A compound having two or more hydroxyl groups, two or more urethane bonds and two or more amide bonds in the molecule, and two or more hydroxyl groups formed by the ring-opening reaction of the cyclic carbonate compound. 3) Compound A-3: A compound having two or more hydroxyl groups and two or more urethane bonds in the molecule, and two or more hydroxyl groups formed by the ring-opening reaction of the cyclic carbonate compound.

Compound A-1 : A compound having two or more hydroxyl groups and two or more amide bonds in one molecule, and two or more hydroxyl groups formed by the ring-opening reaction of a cyclic ester compound. , For example, by reacting a polyvalent carboxylic acid with an excess of a polyvalent amine to give an amino group (-NH
It is obtained by forming an amidoamine having ₂ ) and then subjecting the terminal amino group of this amidoamine to a ring-opening reaction with a cyclic ester compound.

The polyvalent carboxylic acid used for producing the amidoamine is 2 or more in one molecule, preferably 2 to
In the compound having four free carboxyl groups, each of the carboxyl groups is preferably linked via a linear or cyclic carbon chain having 10 or more carbon atoms, preferably 20 to 40 carbon atoms. When the number of carbon atoms connecting the carboxyl groups is smaller than 10, it is difficult to achieve the object of the present invention, which is not preferable.

Examples of such polyvalent carboxylic acids include:
Dodecanedioic acid, brassylic acid, tetradecanedioic acid, pentadecanedioic acid, heptadecanedioic acid, eicosanedioic acid, docosanedioic acid, tetratriacontanedioic acid and the like can be mentioned. These halogen substitution products can also be used.

Further, as the polyvalent carboxylic acid, a dimer acid or trimer acid obtained by dimerizing or trimerizing a monocarboxylic acid having two or more carbon-carbon double bonds in one molecule can also be used. The monocarboxylic acid having 5 or more, preferably 10 or more carbon atoms is preferable, and for example, hexadienoic acid, diallylacetic acid, geranium acid, decadienoic acid, dodecadienoic acid, hexadecadienoic acid, octadecadienoic acid ( Linoleic acid), hexadecatrienoic acid, linolenic acid, octadecatrienoic acid, eicosadienoic acid, eicosatrienoic acid,
Examples thereof include monocarboxylic acids having a conjugated double bond such as docosadienoic acid and docosatrienoic acid. The dimerization and trimerization of these monocarboxylic acids can be performed by a known method.

The polyvalent amine is a compound having two or more amino groups (--NH ₂ ) in one molecule, such as ethylenediamine, hexamethylenediamine, metaxylylenediamine, hydroxyethylaminoethylamine, dimerdiamine, Trimethylhexamethylenediamine,
Examples thereof include diethylenetriamine, triethylenetetramine, diethylaminopropylamine, and of these, hexamethylenediamine, ethylenediamine, trimethylhexamethylenediamine, and metaxylylenediamine are preferable.

The reaction for producing these amidoamines having an amino group (-NH ₂ ) at the terminal by reacting these polyvalent carboxylic acids with polyvalent amines is carried out by a known method.
At 130 to 200 ° C., dehydration reaction is carried out with excess polyvalent amine. The product preferably does not leave free carboxyl groups. The amidoamine has two or more amide groups and two or more amino groups in one molecule.

When the terminal amino group of the thus obtained amidoamine is subjected to a ring-opening reaction at a ratio of about 1 mol of the cyclic ester compound per 1 mol of the amide group, most or all of the amino groups participate in the reaction and the amide Compound A-1 is obtained by forming a bond and introducing a hydroxyl group at the terminal.

The cyclic ester compound is a cyclic compound having an ester bond in the ring, and for example, δ-valerolactone, ε-caprolactone, ξ-enalactone, η-caprylolactone, γ-valerolactone, δ-caprolactone, ε. -Enalactone and ξ-caprylolactone are listed, and those having 6 to 10 carbon atoms are particularly preferable.

The compound A-1 thus obtained is No. 1
Two or more amide bonds, preferably four or more amide bonds in the molecule and two hydroxyl groups based on the ring-opening reaction of the cyclic ester compound.
It is preferable that the compound has one or more compounds, which is linear or branched and has a molecular weight of about 500 to 2,000.

Compound A-2 : Having one or more hydroxyl groups, two or more urethane bonds and two or more amide bonds in one molecule, and the hydroxyl groups being 2 by the ring-opening reaction of the cyclic carbonate compound.
A compound formed by producing at least one of these compounds, for example, by reacting an excess polyvalent amine with a polyvalent carboxylic acid to produce an amidoamine having an amino group (-NH ₂ ) at the terminal,
Then, it is obtained by subjecting the terminal amino group of this amidoamine to a ring-opening reaction with a cyclic carbonate compound.

As the amidoamine having an amino group (-NH ₂ ) at the terminal by reacting a polyvalent carboxylic acid with an excess of a polyvalent amine, those prepared in the same manner as described for the compound A-1 can be used. . Then, the terminal amino group of this amidoamine is subjected to a ring-opening reaction with a cyclic carbonate compound to obtain a compound A-2.

The cyclic carbonate compound is, for example, a cyclic carbonate compound having 2 to 5 carbon atoms such as ethylene carbonate, propylene carbonate and glycerin carbonate, and the ethylene group has 1 to 2 carbon atoms.
Those in which the alkyl group of is substituted are also included.

When the terminal amino group of amidoamine is subjected to a ring-opening reaction at a ratio of about 1 mol of the cyclic carbonate compound per 1 mol of the amide group, most or all of the amino group participates in the reaction to form a urethane bond. At the same time, a hydroxyl group is introduced into the terminal to obtain compound A-2.

The compound A-2 thus obtained is No. 1
A compound having two or more amide bonds, two or more urethane bonds and two or more hydroxyl groups based on the ring-opening reaction of a cyclic carbonate compound in a molecule, which is linear or branched and has a molecular weight of A range of about 500 to 2,000 is preferred.

Compound A-3 : A compound having two or more hydroxyl groups and two or more urethane bonds in one molecule, and two or more hydroxyl groups formed by the ring-opening reaction of the cyclic carbonate compound.

For example, when the above cyclic carbonate compound is reacted at a ratio of about 1 mol per 1 mol of the amino group of the polyvalent amine, the cyclic carbonate compound is opened to form a urethane bond and a hydroxyl group, and the compound A-3 is obtained. Is obtained. The polyvalent amine is a compound having 2 or more, preferably 2 to 4 free amino groups in one molecule, wherein each amino group has 10 or more carbon atoms, preferably 20 to 40 carbon atoms. It is preferable that they are linked via a linear or cyclic carbon chain. When the number of carbon atoms connecting amino groups is less than 10, it is difficult to achieve the object of the present invention, which is not preferable. As such polyvalent amine,
For example, Henkel Hakusui Co., Ltd., trade name, Versamine 55
1 (Versamine 551), which is commercially available, can be used.

The compound A-3 thus obtained is No. 1
A compound having two or more urethane bonds in the molecule and two or more hydroxyl groups based on the ring-opening reaction of a cyclic carbonate compound, which is linear or branched and has a molecular weight of about 500 to 2,000. Ranges are preferred.

The compound A of the present invention is preferably blended in a coating composition used in a field where performance such as coating surface smoothness and electrodeposition coating film forming property is strongly required, and particularly in a cationic electrodeposition coating composition. When compound A is blended, these properties can be remarkably exhibited.

The cationic electrodeposition paint for blending the compound A is not particularly limited, and known ones can be used.

The cationic electrodeposition coating composition is a coating composition containing a cationic base resin and a curing agent as main components. Examples of the cationic base resin include polyepoxides having a number average molecular weight of about 1,000 or more, such as bisphenol type glycidyl ether, phenornovolak type epoxy resin, and epoxy resin in which an epoxy group is directly bonded to an alicyclic skeleton. An amine-added hydroxyl group-containing epoxy resin (substantially free of epoxy groups) obtained by reacting a secondary amine or a tertiary amine is preferable. Examples of these curing agents (crosslinking agents) include a blocked polyisocyanate compound capable of undergoing a crosslinking reaction with the hydroxyl group and an epoxy resin having an alicyclic skeleton directly bonded with an epoxy group. Since such a curing agent is described in detail, for example, in JP-A-47-759 and JP-A-2-255874, the specific description thereof will be replaced with the description in this specification by quoting the publication. Further, a self-curing cationic resin obtained by reacting a part of the functional group of the curing agent with the above-mentioned cationic substrate resin can also be used.

In the present invention, the compounding amount of the compound A is not particularly limited and can be arbitrarily selected according to the purpose.
Total of base resin and curing agent of cationic electrodeposition paint 100
1 to 20 parts by weight, particularly 5 to 15 parts by weight per part by weight is preferable (solid content ratio).

Further, in the coating composition of the present invention, if necessary, an extender pigment, a coloring pigment, a rust preventive pigment, a metallic pigment,
A dispersant, an anti-repellent agent, a curing accelerator and the like can be added.

When the coating composition of the present invention is used as a cationic electrodeposition coating, the electrodeposition coating method is not particularly limited, and it can be carried out under ordinary cationic electrodeposition coating conditions. For example, bath concentration (solid content) 5-4
0% by weight, preferably 10-25% by weight, bath pH 5
A cation electrodeposition bath within the range of 8, preferably 5.5 to 7 was prepared, the object to be coated was the cathode, a stainless steel or carbon plate was used as the anode, and the bath temperature was 20 to 30 ° C and the voltage was 10
0 to 400 V, preferably 20 to 300 V, current density 0.01 to 3 A / dm ² , energization time 1 to 5 minutes, pole area ratio (A / C) 2/1 to 1/2, distance between poles 10 to 100 cm
Then, it is preferable to perform electrodeposition coating in a stirred state.

[0031]

【The invention's effect】

1. The smoothness of the coated surface was remarkably improved. Although the reason is not clear, it is presumed that the carbon chain connecting the carboxyl groups of the polyvalent carboxylic acid in the compound A acts as a plasticizing component and improves the smoothness of the coating film. 2. The electrodeposition coating film forming property was improved, and it became possible to perform electrodeposition coating on a thick film. This is because the amide group and urethane group of the compound A had excellent water retention, and the water content in the analytical coating film was higher than that in the past. 3. The molecular weight of the compound is 500 or more, preferably 500 to
When it is 2,000, and more preferably 700 to 1,300, the weight loss of the coating film at the time of heat curing can be reduced, and the smoothness of the coated surface does not deteriorate. 4. Since the primary or secondary hydroxyl group generated by the ring opening of the cyclic carbonate compound or the cyclic ester compound easily cross-links with the curing agent together with the base resin of the coating composition, the anticorrosion property and the chemical resistance are also improved.

Examples of the present invention and comparative examples will be described below. All parts and percentages are in principle by weight.

I. Preparation of Sample 1) Production of Compound A A reaction vessel equipped with a thermometer, a stirrer, a reflux condenser and a water separator was charged with the first-stage reaction components shown in Table 1 and gradually added to 160 ° C while mixing and stirring. The mixture was warmed, toluene was added at the same temperature, the reaction was carried out while removing the condensed water, and the toluene was removed under reduced pressure. The amine value of the obtained first stage product (polyamidoamine) is also shown in the table. Then, this reaction product was cooled to 120 ° C., then the components of the second stage reaction were charged, heated to 150 ° C., and reacted at the same temperature for 2 hours to obtain compound A-1 or compound A-2. .

[0034]

[Table 1]

Note) Haridimer 200K: manufactured by Harima Kasei Co., Ltd., trade name, dimer acid, acid equivalent 300 Haridimer 500: manufactured by Harima Kasei Co., trade name, dimer acid, acid equivalent 300

Nonvolatile content measurement method: 2 g of the sample (the above reaction product) was precisely weighed (W2) in a tin plate having a diameter of 72 mm which was previously weighed (W1), heated at 105 ° C. for 3 hours, and then weighed again ( It was also determined by substituting these measured values into the following formula. Nonvolatile matter% = [(W3)-(W1)] / [(W2)-
(W1)] × 100

II. Examples and Comparative Examples 100 parts of a cationic resin (Note 1) was added to 100 parts of a curing agent (a) having a solid content of 80% dissolved in ethyl cellosolve (Note 2).
37 parts, compound A-110 parts and formic acid 0.7 parts were added, and deionized water was added with sufficient stirring to obtain a cationic electrodeposition coating composition having a solid content of 20%, pH 6.5 and an emulsion particle size of 0.10 μm. A composition (1) was obtained. Even when the cationic electrodeposition coating composition (1) was sealed and allowed to stand at room temperature for 1 month, almost no separation, sedimentation, increase in particle size, etc. were observed.

Examples 2 to 6 and Comparative Examples 1 to 4 Cationic electrodeposition coating compositions were prepared in the same manner as in Example 1 above, based on the composition and blending amount shown in Table 2.

[0039]

[Table 2]

(Note 1) Cationic resin: EHPE-31
50 (manufactured by Daicel Chemical Co., Ltd., epoxidized vinyl group of 4-vinylcyclohexene-1-oxide ring-opening polymer, the degree of polymerization is 15 to 25, epoxy equivalent 175 to 195) 155 parts, diethanolamine 70
Parts, an epoxy derivative (475 parts of bisphenol A diglycidyl ether having an epoxy equivalent of 190, 285 parts of bisphenol A, 53 parts of diethanolamine and 80 parts of carbitol were heated and dissolved, and then cooled, and the reaction product was kept at 130 ° C. for 3 hours to be reacted. ) At 160 ℃
After reacting for 5 hours, 692 parts of methyl propanol was added,
A cationic resin having a solid content of 60%, an amine value of 63, and a primary hydroxyl group equivalent of 443 was obtained. The above blending amount is for a liquid having a solid content of 60%.

(Note 2) Hardener: Hardener a is the above EHPE
-3150 in ethyl cellosolve. The above blending amount is for a liquid having a solid content of 80%. Hardener b is a complete block compound of isophorone diisocyanate

(Note 3) Compound A: The name of Compound A is based on Table 1 above.

Ratio: A reaction vessel equipped with a thermometer, a stirrer, a reflux condenser and a water separator was charged with 280 parts of oleic acid having an acid equivalent of 280, 136 parts of xylylenediamine and 20 parts of toluene, and mixed and stirred. The mixture was gradually heated to 160 ° C., toluene was added if necessary, and the reaction was carried out while removing condensed water, and then toluene was removed under reduced pressure. The amine value of the obtained first stage product was 141. Then, this reaction product was cooled to 120 ° C., 90 parts of ethylene carbonate was charged, and the mixture was heated to 150 ° C. and reacted at the same temperature for 2 hours to give a solid content of 99.
%, An amine value of 1 gave a comparative compound “ratio”. Molecular weight 489

Ratio: xylylenediamine 1 in a reaction vessel equipped with a thermometer, stirrer, reflux condenser and water separator.
36 parts and 209 parts of propylene carbonate were charged and gradually heated to 150 ° C. with mixing and stirring, and reacted at the same temperature for 2 hours to give a solid content of 97% and an amine value of 2
The comparative compound "ratio" was obtained. Molecular weight 268

Ratio: Sannic Diol PP-4000
(Manufactured by Sanyo Kasei Co., Ltd., trade name)

III. Performance Test Results The cationic electrodeposition paints obtained in the above Examples and Comparative Examples were subjected to chemical conversion treatment with Palbond # 3030 (a zinc phosphate treatment agent manufactured by Nippon Parkerizing Co., Ltd.) Size 0.8 × 150 ×
A 70 mm dull steel plate was dipped and electrodeposition coating was performed using the dull steel plate as a cathode. The electrodeposition coating conditions were a voltage of 200 V and a film thickness (as a cured coating film) of about 20 μm was formed, washed with water and then heated at 160 ° C. for 20 minutes to cure the coating film. The performance test results of the thus obtained cured coating film are shown in Table 3.

[0047]

[Table 3]

Test method Curability: The above paint was applied to a zinc phosphate-treated steel sheet (20 μm based on the cured coating film), baked at 170 ° C. for 20 minutes to cure, and then kept in acetone kept at 40 ° C. for 48 hours. The results (gel fraction) obtained by dipping the coating film before and after dipping were calculated from the following formula (%).

Gel fraction% = [(weight after immersion in acetone−
(Weight of unpainted steel plate) / (Weight before immersion in acetone-Weight of unpainted steel plate)] × 100

Heat loss: The weight of the zinc phosphate-treated steel sheet is W
_0, and a film thickness of 20 μm (based on the cured coating film) was electrodeposited on the steel plate under the above conditions, and the weight in the coating film after being dried under reduced pressure in a vacuum dryer at 80 ° C. for 1 hour was W ₁ And Then, the weight of what was cured by heating this at 180 ° C. for 30 minutes was set to W _2, and these values were substituted into the following formula to determine the heating loss of the coating film. Loss on _{heating% = {(W 1 -W 2} ) / (W 1 -W 0)} × 1
00

SST: Salt spray resistance test. The zinc phosphate-treated steel sheet was electrodeposited under the above conditions (20 μm based on the cured coating film), and baked at 160 ° C. for 10 minutes to cure. This coated plate was subjected to a salt spray resistance test according to JIS Z2871 (1,000 hours), and a clique width (one side) within 2.0 mm from a cut portion (a linear scratch reaching the base) and a coating film other than the cut portion The blister of 8F (ASTM) or less was regarded as a pass.

Film thickness retention: The initial film thickness is the film thickness when a zinc phosphate-treated steel sheet is immersed in the above paint immediately after preparation and electrodeposition coated at 200 V for 3 minutes, and the paint is hermetically stirred at 30 ° C. for 2 weeks. After that, the film thickness at the time of electrodeposition coating at 200 V for 3 minutes was taken as the elapsed film thickness. The state of the coated surface was visually evaluated.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Jiro Nagaoka 4-17-1, Higashihachiman, Hiratsuka City, Kanagawa Kansai Paint Co., Ltd.

Claims (2)

[Claims] 1. A ring-opening of a cyclic carbonate compound or a cyclic ester compound, which has two or more hydroxyl groups in one molecule and two or more amide bonds and / or two or more urethane bonds. A coating composition comprising a compound having a molecular weight of 500 or more produced by the reaction. 2. A cationic electrodeposition coating composition containing the compound of claim 1.