JPH0873783A - Matte electrodeposition coating composition and its production - Google Patents

Abstract

PURPOSE: To produce a matte electrodeposition coating composition which forms a coating film having good matte effect and good appearance and in which c constituent acrylic copolymer resin is stable by using the specified acrylic copolymer resin and an amino resin as the principal components. CONSTITUTION: The production process comprises mixing a water-soluble or water-dispersible acrylic copolymer resin (a) obtained by copolymerizing radical- polymerizable monomers in the presence of a chain transfer agent having a hydrolyzable-silyl-containing chain of the formula (R<1> is an organic group; R<2> is a hydrolyzable group; R<3> is H, alkyl or aryl; and n is 1-3) with an amino resin (b) being an alkyl-etherified methylol-melamine resin which has at least 3.5 ether groups on the average per melamine nucleus and in which 20-100 % of the ether groups are butoxy groups in a weight ratio (a)/(b) of 30/70 to 80/20 (in terms of the solid matter), neutralizing part of the carboxyl groups of the resin with a basic substance and optionally adding a surfactant, a wax, a colorant, etc. to the mixture.

Description

Detailed Description of the Invention

[0001]

Industrial Applicability The present invention controls the matting degree by introducing a hydrolyzable silyl group at the terminal of an acrylic copolymer resin and crosslinking it to improve the viscosity and stability of the acrylic copolymer resin. And a matte electrodeposition coating composition.

[0002]

BACKGROUND OF THE INVENTION Electrodeposition coating compositions for obtaining a matte coating film by utilizing the crosslinking of hydrolyzable silyl groups include hydrolyzable silyl group-containing compounds having a double bond. Is introduced by copolymerization (for example, JP-B-62-24519), a method of reacting a carboxylic acid in the molecule with an epoxysilane compound (for example, JP-A-2-269780).
No.), etc., and a curing agent such as an acrylic copolymer resin and a curing agent such as an amino resin dispersed in water are proposed. However, since the acrylic copolymer resin obtained by these methods has a hydrolyzable silyl group in the side chain, self-crosslinking of the silane group and reaction with other functional groups in the molecule lead to high viscosity and storage stability. There are drawbacks such as poor performance. Furthermore, the reaction may proceed inside the dispersed particles even after being made into an electrodeposition coating, which may cause fluctuations in gloss, roughening of the coating film and sedimentation of the dispersed particles.

Therefore, an object of the present invention is to provide a composition for a matte electrodeposition coating composition, which forms a matte coating film having good matteness and coating appearance and improves the stability of an acrylic copolymer resin. Is to provide.

[0004]

As a result of earnest research in view of the above problems, the present inventors have found that when a hydrolyzable silyl group is introduced at the terminal of a molecular chain, an acrylic copolymer having low viscosity and good stability is obtained. A resin is obtained, and a composition prepared by blending an acrylic copolymer resin having a hydrolyzable silyl group at the molecular chain end and an amino resin is neutralized and diluted with water to obtain a water-dispersed matte electrodeposition. It has been found that a coating composition can be obtained, and that by using the matte electrodeposition coating composition, a coating film having a good matting effect and coating film appearance can be obtained.

That is, the matte electrodeposition coating composition of the present invention comprises (a) at least one molecular terminal represented by the general formula:

[Chemical 3] (However, R ¹ is an organic group, R ² is a hydrolyzable group, R ³ is hydrogen,
It is at least one substituent selected from an alkyl group and an aryl group, and n is an integer of 1 to 3. ) Water-soluble or water-dispersible acrylic copolymer resin having a hydrolyzable silyl group-containing chain represented by
(b) Amino resin 20 to 70% by weight of solid content.

The method for producing the matte electrodeposition coating composition of the present invention has the general formula:

[Chemical 4] (However, R ¹ is an organic group, R ² is a hydrolyzable group, R ³ is hydrogen,
It is at least one substituent selected from an alkyl group and an aryl group, and n is an integer of 1 to 3. In the presence of a chain transfer agent having a hydrolyzable silyl group-containing chain represented by the above), the acrylic copolymer resin is prepared by polymerizing a radical polymerizable monomer containing at least one acrylic monomer. It is characterized in that it is prepared.

Hereinafter, the present invention will be described in detail. (a) Water-soluble or hydrolyzable silyl group at the end of the chain
Or water-dispersible acrylic copolymer resin This acrylic copolymer resin has the following general formula (1):

[Chemical 5] (However, R ¹ is an organic group, R ² is a hydrolyzable group, R ³ is hydrogen,
It is at least one substituent selected from an alkyl group and an aryl group, and n is an integer of 1 to 3. ) Is obtained by copolymerizing a radically polymerizable monomer in the presence of a chain transfer agent having a hydrolyzable silyl group-containing chain. As a radically polymerizable monomer, (2) ethylenically unsaturated carboxylic acid monomer, (3) hydroxyl group-containing polymerizable unsaturated monomer, (4) ethylenically unsaturated carboxylic acid ester monomer And / or vinyl monomers are preferably used. At least one of the components (2) to (4) is an acrylic type. The resulting acrylic copolymer resin has an acid value of 20.
˜150, preferably 30 to 100, and the hydroxyl value is 30 to 150, preferably 40 to 100.

As the component (1), the hydrolyzable group R ² is 1 to
A mercaptosilane compound having three is used. When the number of hydrolyzable groups is 2 or less, the remaining substituent R ³ is hydrogen, an alkyl group or an aryl group. Note that R ³ in the formula is 2
When there are two (when n = 1), R ³ need not be the same and may be different substituents. Preferred components (1) include mercaptoethyltrimethoxysilane, mercaptoethyltriethoxysilane, mercaptoethylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane,
3-mercaptopropylmethyldimethoxysilane, 3-
Examples thereof include mercaptodialkoxysilane compounds such as mercaptopropyltris (trimethylsiloxy) silane and mercaptotrialkoxysilane compounds.

The component (1) is used in an amount of 0.1 to 30% by weight, preferably 0.5 to 10% by weight, based on 100% by weight of the component (a), based on the solid content. If it is less than 0.1% by weight, the matting effect cannot be sufficiently obtained, and if it exceeds 30% by weight, the molecular weight is lowered to deteriorate water resistance and weather resistance, and the acrylic copolymer resin is gelated.

The component (1) is usually added to the above radical-polymerizable monomer mixture, and when added dropwise, it acts as a chain transfer agent and is introduced at the molecular chain end of the acrylic copolymer. However, the addition method is not limited to this,
It may be charged in the polymerization vessel in advance or added during the polymerization.

The component (2) mainly imparts water dilutability, electrophoretic property, catalytic action at the time of curing, etc. to the acrylic copolymer resin, and is, for example, acrylic acid, methacrylic acid, crotonic acid, vinyl acetic acid, itacone. Acid, maleic acid, maleic anhydride, phthalic acid and the like can be mentioned. These may be used alone or in combination of two or more. Such component (2) has an acid value of the acrylic copolymer resin (a) of 20 to 150.
, Preferably in the range of 30 to 100.
When the acid value of the acrylic copolymer resin (a) is less than 20, water dilutability and matteness are deteriorated, and when it exceeds 150, water resistance and weather resistance are deteriorated.

Further, the component (3) mainly imparts curability with a melamine resin which is a curing agent, and for example, 2-
Examples thereof include hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate and hydroxybutyl methacrylate. These may be used alone or in combination of two or more. Such component (3) is an acrylic copolymer resin
It is used in such a range that the hydroxyl value in (a) is 30 to 150, preferably 40 to 100. If the hydroxyl value is less than 30, the curability will be insufficient, and if it exceeds 150, the coating film will become brittle and the water resistance will decrease.

Further, the component (4) is a component mainly forming the skeleton of the acrylic copolymer resin, and in addition to an alkyl ester such as acrylic acid or methacrylic acid, a usual vinyl monomer can be used. Examples of these include, for example, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, n-propyl acrylate, n-propyl methacrylate, isopropyl acrylate, isopropyl methacrylate, n.
-Butyl acrylate, n-butyl methacrylate, isobutyl acrylate, isobutyl methacrylate, t
-Butyl acrylate, t-butyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, lauryl acrylate, lauryl methacrylate, stearyl acrylate, stearyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, dimethylaminoethyl methacrylate, methylol acrylamide, methylol methacrylamide, n -Butoxymethyl acrylamide, n-butoxymethyl methacrylamide, propoxymethyl acrylamide, propoxymethyl methacrylamide and other acrylic acids, methacrylic acid and other esters, styrene,
Examples thereof include vinyl monomers such as methylstyrene, vinyltoluene, vinyl acetate, acrylonitrile, acrylamide and methacrylamide. These may be used alone or in combination of two or more.

The amount of the ethylenically unsaturated carboxylic acid monomer (2) used is the amount necessary to give a predetermined acid value as described above. Specifically, the sum of (2) + (3) + (4) is 10
The amount of 0% by weight is preferably 3 to 20% by weight, more preferably 7 to 15% by weight.

Further, the amount of the hydroxyl group-containing polymerizable unsaturated monomer (3) used is an amount necessary to give a predetermined hydroxyl value as described above. Specifically, (2) + (3) +
The total amount of (4) is preferably 6 to 30% by weight, more preferably 10 to 25% by weight, based on 100% by weight.

Further, the amount of the ethylenically unsaturated carboxylic acid ester monomer and / or vinyl monomer (4) used is an amount necessary for forming the skeleton of the acrylic copolymer resin (a). Specifically, the total of (2) + (3) + (4) is 100% by weight.
20 to 91% by weight is preferable, and more preferably 60 to 83
Weight%

Acrylic copolymer resin (a) as described above
Is a solution polymerization of the above-mentioned monomers, non-moisture polymerization, bulk polymerization,
It can be obtained by polymerization by a known method such as emulsion polymerization or suspension polymerization, but is particularly preferably obtained by a solution polymerization method using a hydrophilic solvent such as isopropyl alcohol, n-butyl alcohol, ethyl cellosolve or butyl cellosolve.

The number average molecular weight of the acrylic copolymer resin (a) thus obtained is preferably 3,000 to 70,000.
When the number average molecular weight is 3,000 or more, sufficient coating film durability can be obtained, and when it is 70,000 or less, water-soluble or water-dispersible type is easily obtained, viscosity is appropriate, and handleability is good. Especially in terms of matteness and coating stability, the number average molecular weight is 5,
It is preferably 000 to 50,000. The preferred glass transition temperature of the acrylic copolymer resin (a) is −10 to 60 ° C., and 20 to 50 ° C. is particularly preferred in terms of matteness and flexibility.

(B) Amino Resin The crosslinking agent used in the present invention is an amino resin. The amino resin is, for example, melamine resin or benzoguanamine resin, preferably melamine resin. As the melamine resin, an alkoxy group such as n-butylated melamine resin and isobutylated melamine resin is a methoxy group, an ethoxy group, and
Examples thereof include alkoxymethylated melamine resins (alkyl etherified methylol melamine resins) such as -butoxy group and i-butoxy group. These resins are usually obtained by subjecting melamine to an addition reaction or an addition condensation reaction of an aldehyde such as formaldehyde or paraformaldehyde with an etherification with a monohydric alcohol having 1 to 4 carbon atoms.

In the present invention, a methyl / butyl mixed ether type melamine is preferably used, and per melamine nucleus,
It has an average of 3.5 or more ether groups.
Alkyl etherified methylol melamine resins having 20 to 100% butoxy groups are preferred. In this case, the butoxy group may be any of n-butoxy group, i-butoxy group and t-butoxy group. The average number of ether groups is 3.5
If it is less than the number, sufficient matting effect cannot be obtained. The preferred number of ether groups contained is 4.5 or more on average. If the butoxy group content is less than 20%, the matting effect is reduced. The butoxy group content is preferably 30% or more. The melamine used is not limited to one kind, and if the ratio of butoxy groups in the mixed melamine falls within the above range,
You may mix two or more types of melamine. In addition,
The average degree of polymerization of melamine resin is 3.0 in terms of stability of aqueous solution.
It is preferably a nucleus or less.

Acrylic copolymer resin of the resin composition of the present invention
The mixing ratio of (a) and amino resin (b) is 30/70 to 80/20, preferably 40/60 to 70/30 in terms of weight ratio ((a) / (b)) based on solid content. Is. If the weight ratio is less than 30/70, the stability of the coating composition is impaired, while if it exceeds 80/20, the hardness and chemical resistance of the coating film decrease. The mixing method of the component (a) and the component (b) is not particularly limited, and may be a temperature not higher than the temperature at which the component (a) and the component (b) do not react with each other to increase the molecular weight.

In order to make the obtained resin composition water-soluble or water-dispersible (water-dilutable), at least a part of the carboxyl groups in the resin is neutralized with a basic substance such as an organic amine or an inorganic base. Is preferred. As the basic substance, organic amines such as monomethylamine, dimethylamine, trimethylamine, diethylamine, triethylamine, monoisopropylamine, diisopropylamine, triethanolamine, dimethylethanolamine and diethylethanolamine, or ammonia is preferable. The neutralization rate with such basic substances is 30-
100% is suitable, but 40 to 95% is particularly preferable because it has good water dilutability and does not cause uneven gloss.

The basic substance is composed of the component (a) and the component (a).
Water dilutability may be imparted by adding before mixing (b) or after mixing component (a) and component (b) to neutralize at least part of the carboxyl groups.

Further, if desired, a surfactant for improving unevenness in dryness and washability, a pigment for improving matting and improving smoothness, a wax for improving smoothness and matting, latex, etc. A colorant, a plasticizer, an acidic / basic substance, etc. can be appropriately added. These mixtures are diluted with water and used as a matte electrodeposition paint.
If necessary, other acrylic resin or melamine resin,
It can be added within a range that does not impair the effects of the present invention.

The article to be coated is dipped in an electrodeposition coating composition bath containing such an electrodeposition coating composition of the present invention, and the article to be coated is used as an anode for electrodeposition coating. At this time, the solid content concentration of the coating composition in the electrodeposition coating bath is suitably 5 to 15% by weight. If it is less than 5% by weight, the coating voltage becomes too high, while if it exceeds 15% by weight, the loss to the outside of the coating system is large and it is not economical. In addition, the electrodeposition coating is usually performed at an electrodeposition coating bath temperature of 15 to 35 ° C and a coating voltage of 50 to 50 ° C.
It can be performed under the conditions of 250V and electrodeposition time of 1 to 5 minutes.

According to such a method for forming a matte electrodeposition coating film of the present invention, the film thickness of the coating film can be appropriately selected and adjusted within the range of 5 to 60 μm. If necessary, wash the electrodeposition-coated object with water, and then heat-cure it at 120-200 ° C for 10-60 minutes to form a matte electrodeposition coating with a stable gloss and excellent appearance and hardness. It

The article to be coated which can be applied to the matte electrodeposition coating method of the present invention has conductivity and is not particularly limited,
When aluminum or aluminum alloy is used as the object to be coated, a uniform matte coating film excellent in smoothness etc. can be obtained, and the matte finish has a high hardness and a dull appearance in which the die marks of the aluminum material are not conspicuous. A coating film can be obtained.

[0028]

The present invention will be described in more detail with reference to the following specific examples. The acrylic copolymer resin (a) and amino resin (b) used in Examples and Comparative Examples are as follows.

(A) Acrylic Copolymer Resin The ones synthesized according to the following Synthesis Examples 1 to 4 and Comparative Synthesis Examples 1 and 2 were used. Synthesis Example 1 Production of acrylic copolymer resin (A-1) 44 parts by weight of isopropyl alcohol and n-
12 parts by weight of butyl alcohol was charged and the temperature was raised to 80 ° C.
The compound (1) containing at least one alkoxy group in the hydrolyzable silyl group and having a mercapto group and a hydrolyzable silyl group in the molecule as shown in Table 1 below is mercaptopropyltrimethoxysilane (MS ) 1.0 part by weight,
7.0 parts by weight of acrylic acid (AA) as ethylenically unsaturated carboxylic acid monomer (2), 20 parts by weight of 2-hydroxyethyl methacrylate (2HEMA) as hydroxyl group-containing polymerizable unsaturated monomer (3), ethylenic 32 parts by weight of methyl methacrylate (MMA) as an unsaturated carboxylic acid ester monomer and / or vinyl monomer (4), 20 parts by weight of n-butyl methacrylate (NBMA), butyl acrylate (BA)
A mixture of 16 parts by weight, 5 parts by weight of N-n-butoxymethylacrylamide (BMAM) and 0.4 parts by weight of azoisobutyronitrile was added dropwise at reflux temperature over 4 hours. One hour after the completion of dropping, 0.8 part by weight of azoisobutyl nitrile and 10 parts by weight of isopropyl alcohol were further added to 4 parts.
The mixture was added every 30 minutes and the polymerization was completed by stirring for 1 hour after completion of the addition, and diluted with 23 parts by weight of n-butyl alcohol to obtain an acrylic copolymer resin solution (A-1).

Synthesis Example 2 Production of Acrylic Copolymer Resin (A-2) Based on the blending amounts of components (1) to (4) shown in Table 1 below,
An acrylic copolymer resin (A-2) was produced in the same manner as in Synthesis Example 1.

Synthesis Example 3 Production of Acrylic Copolymer Resin (A-3) 44 parts by weight of isopropyl alcohol and n-
12 parts by weight of butyl alcohol was charged and the temperature was raised to 80 ° C.
As shown in Table 1 below, 7.0 parts by weight of acrylic acid (AA) was used as the ethylenically unsaturated carboxylic acid monomer (2), and 2-hydroxyethyl was used as the hydroxyl group-containing polymerizable unsaturated monomer (3). 20 parts by weight of methacrylate (2HEMA), methyl methacrylate (MMA) as ethylenically unsaturated carboxylic acid ester monomer and / or vinyl monomer (4)
) 32 parts by weight, 20 parts by weight of n-butyl methacrylate (NBMA), 16 parts by weight of butyl acrylate (BA), 5 parts by weight of N-n-butoxymethylacrylamide (BMAM) and 0.4 parts by weight of azoisobutyl nitrile. It was added dropwise at reflux temperature for 4 hours. After the dropwise addition, 2.0 parts by weight of mercaptopropyltrimethoxysilane (MS) was added as a compound (1) containing at least one alkoxy group in the hydrolyzable silyl group and having a mercapto group and a hydrolyzable silyl group in the molecule. . After 1 hour from the end of the addition, 0.8 part by weight of azoisobutyl nitrile and 10 parts by weight of isopropyl alcohol were added in four batches every 30 minutes, and after the addition was completed, the mixture was stirred for another 1 hour to complete the polymerization. -Butyl alcohol was diluted with 23 parts by weight to obtain an acrylic copolymer resin solution (A-3).

Synthesis Example 4 Production of Acrylic Copolymer Resin (A-4) Based on the blending amounts of components (1) to (4) shown in Table 1 below,
An acrylic copolymer resin (A-4) was produced in the same manner as in Synthesis Example 3.

Comparative Synthesis Example 1 Production of Acrylic Copolymer Resin (A-5) 44 parts by weight of isopropyl alcohol and n-
12 parts by weight of butyl alcohol was charged and the temperature was raised to 80 ° C.
As shown in Table 1 below, 7.0 parts by weight of acrylic acid (AA) as the ethylenically unsaturated carboxylic acid monomer (2),
2- as the hydroxyl group-containing polymerizable unsaturated monomer (3)
20 parts by weight of hydroxyethyl methacrylate (2HEMA),
Methyl methacrylate (MM) as ethylenically unsaturated carboxylic acid ester monomer and / or vinyl monomer (4)
A) 32 parts by weight, n-butyl methacrylate (NBMA) 20 parts by weight, butyl acrylate (BA) 16 parts by weight and N-n-
A mixture of 5 parts by weight of butoxymethyl acrylamide (BMAM) and 0.4 parts by weight of azoisobutyl nitrile was added dropwise at reflux temperature over 4 hours. One hour after the end of the addition, 0.8 part by weight of azobisisobutylnitrile and 10 parts by weight of isopropyl alcohol were added in four batches every 30 minutes, and after the addition was completed, the mixture was stirred for another hour to complete the polymerization. Was diluted with 23 parts by weight of n-butyl alcohol to obtain an acrylic copolymer resin solution (A-5).

Comparative Synthesis Example 2 Production of Acrylic Copolymer Resin (A-6) 44 parts by weight of isopropyl alcohol and n-
12 parts by weight of butyl alcohol was charged and the temperature was raised to 80 ° C. As shown in Table 1 below, 7.0 parts by weight of acrylic acid (AA) was used as the ethylenically unsaturated carboxylic acid monomer (2), and 2-hydroxyethyl was used as the hydroxyl group-containing polymerizable unsaturated monomer (3). 20 parts by weight of methacrylate (2HEMA), methyl methacrylate (MMA) as ethylenically unsaturated carboxylic acid ester monomer and / or vinyl monomer (4)
30 parts by weight, 20 parts by weight of n-butyl methacrylate (NBMA), 16 parts by weight of butyl acrylate (BA), 5 parts by weight of N-n-butoxymethylacrylamide (BMAM) and 2 parts by weight of methacryloxypropyltrimethoxysilane (MPS) A mixture of 0.4 parts by weight of azoisobutyl nitrile was added dropwise at reflux temperature over 4 hours. After 1 hour from the end of the addition, 0.8 parts by weight of azoisobutyl nitrile and 10 parts by weight of isopropyl alcohol were added in 4 batches every 30 minutes, and after the addition was completed, the mixture was stirred for 1 hour to complete the polymerization. -Butyl alcohol was diluted with 23 parts by weight to obtain an acrylic copolymer resin solution (A-6).

Table 1 Ingredients (parts by weight) A-1 A-2 A-3 A-4 A-5 A-6 Ingredient (1) MS 1.0 2.0 2.0 4.0--(Method of addition) Simultaneous⁽¹⁾ After simultaneous dropping⁽²⁾After dripping-- Ingredient (2) AA 7.0 7.0 7.0 7.0 7.0 7.0 Ingredient (3) 2 HEMA 20.0 20.0 20.0 20.0 20.0 20.0 Ingredient (4) MMA 32.0 32.0 32.0 32.0 32.0 30.0 NBMA 20.0 20.0 20.0 20.0 20.0 20.0 BA 16.0 16.0 16.0 16.0 16.0 16.0 BMAM 5.0 5.0 5.0 5.0 5.0 5.0 MPS-----2.0

Note (1): Added by mixing with component (2) to component (4) Note (2): added after dropping component (2) to component (4)

The above Synthesis Examples 1 to 4 and Comparative Synthesis Examples 1 and 2
The acrylic copolymer resin (A-1 to A-6) shown in 1 was sealed in a glass bottle and stored at 50 ° C. for 2 weeks, and then the state was visually observed. Table 2 shows the results. As is clear from Table 2, the acrylic copolymer resins (A-1 to A-4) are stable, while the acrylic copolymer resin (A-6) having a hydrolyzable silyl group in the side chain is stable. Poor property, causing gelation.

Table 2 Storage stability A-1 A-2 A-3 A-4 A-5 A-6 50 ° C. × 2 weeks No abnormalities No abnormalities No abnormalities No abnormalities No abnormalities Gelation

(B) The following alkyl etherified methylol melamine resin was used as the amino resin as the amino resin curing agent. B-1: [Cymel 235, manufactured by Mitsui Cyanamide Co., Ltd., solid content 100% by weight] (butoxy / methoxy ratio = 40/60) B-2: [Mycoat 506, manufactured by Mitsui Cyanamide Co., Ltd.,
Solid content 96% by weight] (Butoxy / methoxy ratio = 100/0)

Example 1 To 191.2 parts by weight of the acrylic copolymer resin (A-1) of Synthesis Example 1,
49.4 parts by weight of melamine resin (B-1) and 33.0 parts by weight of (B-2) were added, and the mixture was stirred at 25 ° C. for 30 minutes to mix to obtain a composition for a matte electrodeposition coating composition. To this was added 5.9 parts by weight of triethylamine, and the mixture was further stirred at 25 ° C. for 10 minutes, and then deionized water was gradually added to dilute the mixture to prepare an electrodeposition coating having a resin solid content of 10%. The composition is shown in Table 3 below.

This electrodeposition coating was placed in an electrodeposition tank, and after the alumite treatment, the AC-colored 6063S aluminum plate was used as an anode at a bath temperature of 21 ° C. for 2.5 minutes at a predetermined voltage (80 to 180 V) to prepare a coated plate. . After the electrodeposition was completed, these coated plates were washed with washing water containing 2% by weight of isopropanol and 1% by weight of butyl cellosolve, and heat-cured at 180 ° C. for 30 minutes. The results of evaluating the performance of the obtained electrodeposition coating film are shown in Table 4 below.

Evaluation Method and Evaluation Criteria (1) Glossiness The glossiness by 60 ° reflection was measured according to JIS K 5400 7.6, and the matteness was judged by the magnitude of the glossiness. In general,
The lower the glossiness, the better the matteness.

(2) Appearance of coating film The surface of the electrodeposition coating film after baking was visually observed to evaluate whether or not rough skin was noticeable. ◎ ‥‥ Excellent ○ ‥‥‥ Good △ ‥‥‥ Slightly bad (graininess is observed) × ‥‥‥ Poor

(3) Hardness The coating film after baking was gradually cooled to 20 ° C., and then a pencil scratching test was conducted according to JIS K 5400 8.4. The hardness of the coating film is represented by the hardness of the pencil in which the coating film is peeled off.

(4) Adhesiveness: 1 × 10 mm, 10 × 10 goggles eyes test (JIS K 5400 compliant)
Then, the adhesiveness to the aluminum substrate was displayed by the number not peeled / 100.

Examples 2 to 5 Based on the compositions shown in Table 3 below, electrodeposition coating compositions were prepared in the same manner as in Example 1, and electrodeposition coating films were prepared in the same manner as in Example 1. The results of evaluating the performance of the obtained electrodeposition coating film in the same manner as in Example 1 are shown in Table 4 below.

Comparative Example 1 49.2 parts by weight of melamine resin (B-1) and 33.0 parts by weight of (B-2) were added to 190.2 parts by weight of the acrylic resin (A-5) of Synthesis Example 5, and the mixture was added at 25 ° C. for 30 minutes. Stirring and mixing were performed to obtain a matte electrodeposition coating composition. To this was added 5.9 parts by weight of triethylamine, and the mixture was further stirred at 25 ° C. for 10 minutes, and then deionized water was gradually added to dilute the mixture to prepare an electrodeposition coating having a resin solid content of 10%. The composition is shown in Table 3 below.

This electrodeposition coating was placed in an electrodeposition tank, and after the alumite treatment, an AC-colored 6063S aluminum plate was used as an anode at a bath temperature of 21 ° C. for 2.5 minutes at a predetermined voltage (80 to 180 V) to prepare a coated plate. . After the electrodeposition was completed, these coated plates were washed with washing water containing 2% by weight of isopropanol and 1% by weight of butyl cellosolve, and heat-cured at 180 ° C. for 30 minutes. The results of evaluating the performance of the obtained electrodeposition coating film in the same manner as in Example 1 are shown in Table 4 below.

Comparative Example 2 An electrodeposition coating composition was prepared in the same manner as in Comparative Example 1 based on the composition shown in Table 3 below, and an electrodeposition coating film was prepared in the same manner as in Comparative Example 1. The results of evaluating the performance of the obtained electrodeposition coating film in the same manner as in Example 1 are shown in Table 4 below.

Table 3 Composition of Electrodeposition Paint Example Example Example Example Example Example Example Comparative Example Comparative Example (Part by weight) 1 Two Three Four 5 1 Two (a) Acrylic resin A-1 191.2------A-2-192.2-----A-3--192.2----A-4---194.2 194.2--A-5-- ---190.2-A-6------190.2 (b) Melamine resin B-1 49.4 49.4 49.4 49.4 56.8 49.4 49.4 B-2 33.0 33.0 33.0 33.0 25.3 33.0 33.0 Triethylamine 5.9 5.9 5.9 5.9 5.9 5.9 5.9 5.9

Table 4 Example Example Example Example Example Example Example Comparative Example Comparative Example Coating properties 1 Two Three Four 5 1 Two Gloss 15 25 7 5 10 70 3 Appearance ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ Hardness 4H 4H 4H 4H 4H 4H 4H Adhesion 100/100 100/100 100/100 100/100 100/100 100/100 100/100 (1 After a month) Paint bath Good Good Good Good Good Good Good Sedimentation Appearance ◎ ◎ ◎ ◎ ◎ ◎ ◎ △

As is clear from Table 4, the electrodeposition coating films of Examples 1 to 4 have low glossiness (good matteness) and excellent coating appearance. Further, the electrodeposition coating film of Comparative Example 1 has a high glossiness, and the electrodeposition coating film of Comparative Example 2 causes sedimentation of the paint and deterioration of the coating film over time, resulting in poor paint stability.

[0052]

[Effect] As described in detail above, the resin composition for a matte electrodeposition coating composition of the present invention is a mixture of an acrylic copolymer resin having a hydrolyzable silyl group at the end of the molecular chain of the acrylic copolymer resin and an amino resin. Since this is used as an electrodeposition paint, a matte coating film having good mattability and coating film appearance is formed. In addition, the stability of the paint is excellent, and the paint does not sediment or the appearance of the coating film deteriorates over time. Further, the acrylic copolymer resin of the present invention has a low viscosity and is excellent in storage stability as compared with a resin having a hydrolyzable silyl group in its side chain.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical indication location C09D 161/32 PHK (72) Inventor Masatoshi Ono 4-1-1-15 Minamishinagawa, Shinagawa-ku, Tokyo Japan Paint Co., Ltd. Tokyo office (72) Inventor Yukihiko Nishitani 4-1-1 Minami Shinagawa, Shinagawa-ku, Tokyo Japan Paint Co., Ltd. Tokyo office

Claims (3)

[Claims] 1. (a) at least one molecular terminus has the general formula: (However, R ¹ is an organic group, R ² is a hydrolyzable group, R ³ is hydrogen,
It is at least one substituent selected from an alkyl group and an aryl group, and n is an integer of 1 to 3. ) A water-soluble or water-dispersible acrylic copolymer resin having a hydrolyzable silyl group-containing chain represented by 30% by weight of solid content of 30 to 80%, and (b) 20% to 70% by weight of solid content of amino resin. A characteristic matte electrodeposition coating composition. 2. The matte electrodeposition coating composition according to claim 1, wherein the amino resin (b) has an average of 3.5 or more ether groups per melamine nucleus, and 20 to 10 of the ether groups are contained. A matte electrodeposition coating composition, which is an alkyl etherified methylol melamine resin having 100% butoxy groups. 3. A method for producing the matte electrodeposition coating composition according to claim 1 or 2, comprising the general formula: (However, R ¹ is an organic group, R ² is a hydrolyzable group, R ³ is hydrogen,
It is at least one substituent selected from an alkyl group and an aryl group, and n is an integer of 1 to 3. In the presence of a chain transfer agent having a hydrolyzable silyl group-containing chain represented by the above), the acrylic copolymer resin is prepared by polymerizing a radical polymerizable monomer containing at least one acrylic monomer. A method of preparing.