JPH0339369A - Anionic dull electrodeposition coating composition - Google Patents

Abstract

PURPOSE:To obtain the title composition which forms dull coating films having excellent durability and esthetic effect by using a base of mixed resin containing a specific fluororesin and a crosslinking agent. CONSTITUTION:The subject composition comprises (A) a resin base of (i) a resin of 40 to 150 acid value and (ii) another resin of an acid value smaller than (i) wherein the difference is 40 or more and components i and/or ii are fluorine-containing resin, and (B) a crosslinking agent. The acid value of component (i) is preferably 50 to 120 and the acid value difference between components (i) and (ii) is more than 60.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an anionic matte electrodeposition coating composition.

[Prior Art] Paints containing an acrylic-melamine resin as a vehicle component are conventionally known as electrodeposition paint compositions that are applied to mW of aluminum materials.

However, the weather resistance of the electrodeposited film formed from the above-mentioned paint is of a sufficiently satisfactory level when used for general houses.

In the case of construction materials for buildings, there has recently been a demand for long-term durability of several decades, so these paints cannot meet the above-mentioned requirements.

Furthermore, in this field, diversification of user needs has led to a lack of metallic luster, and there is now a strong demand for matte coatings that create a calm atmosphere. Conventionally, as a method for obtaining a matte coating film, it has been known to use an electrodeposition paint composition in which an aqueous dispersion of wax is blended into the electrodeposition paint. However, the coating composition is
The disadvantage is that the wax component separates from the base resin, crosslinking agent, etc. in the paint, and these components stand out on the surface of the paint, adversely affecting the finish of the matte coating, and the stability of the paint is also poor.

[Problems to be Solved by the Invention] The present invention has been made with the object of providing a coating composition that forms a matte coating film with excellent durability and cosmetic properties and also has excellent stability.

[Means for Solving the Problems] As a result of various studies on methods for overcoming the above-mentioned problems, the present inventors have developed a coating composition whose vehicle component is a resin obtained by mixing two types of resins with different acid values. The present inventors have discovered that the present invention can form a matte coating film with excellent stability, durability, and cosmetic properties, and have completed the present invention.

That is, the present invention contains a base resin and a crosslinking agent as essential components, and the base resin is a mixture of resin (A) and resin (B), and at least of these resins (A) and resin (B). 61 types of resins are fluorine-containing resins, and the acid value of resin (A) is 40 to 150, and the acid value of resin (B) is lower than that of resin (A), and the difference is at least 40. The present invention relates to an anionic matte electrodeposition coating composition characterized by:

As the resin (A) of the base resin used in the composition of the present invention, any resin having an acid value within the above-mentioned range can be suitably selected from conventional resins without any particular restriction. The latter, such as fluororesins and vinyl resins, are preferred because they have excellent weather resistance, durability, etc. of the membrane.

The fluororesin is a resin having at least 6 fluorine atoms and a carboxyl group in one molecule, and specifically, for example, a hydroxyl group-containing fluoropolymer containing fluoroolefin and hydroxy vinyl ether as essential monomer components. A resin obtained by reacting a tribasic acid anhydride with a tribasic acid anhydride (for example, JP-A-62-127362), and a resin having a perfluoroalkyl group or a perfluoroalkenyl group at one end and an ethylenic dianhydride at the other end. Monomers having heavy bonds (e.g. perfluorooctylethyl methacrylate, perfluoroisononylethyl methacrylate, etc.) (JP-A-5
6-167139), ethylenically unsaturated carboxylic acids (e.g. (meth)acrylic acid, crotonic acid, (anhydride)
maleic acid, itaconic acid, fumaric acid, etc.) and optionally a hydroxyl group-containing polymerizable unsaturated monomer (e.g., hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, etc.). Examples include resin. In addition, other polymerizable unsaturated monomers described for vinyl resins can be used in appropriate combination with the above-mentioned polymers as monomer components.

In the case of fluoroolefins, the content of fluorine atoms in the fluororesin is preferably in the range of about 30 to 70% by weight, preferably 40 to 60% by weight, as a monomer component containing fluorine atoms. , about 10 to 9 in the case of perfluoroalkyl or perfluoroalkenyl monomers
A range of 0% by weight is preferable.

In addition, the above-mentioned vinyl resin 1 is obtained by polymerizing the ethylenically unsaturated carboxylic acid and, if necessary, the hydroxyl group-containing polymerizable unsaturated monomer and other polymerizable unsaturated monomers. Polymers may be mentioned as preferred.

Other polymerizable unsaturated monomers include, for example, methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, butyl acrylate, hexyl acrylate, octyl acrylate, lauryl acrylate, Cyclohexyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate,
Alkyl (C,-,,) esters of acrylic acid or methacrylic acid such as isopropyl methacrylate, butyl methacrylate, hexyl methacrylate, octyl methacrylate, and lauryl methacrylate: Vinyl aromas such as styrene, α-methylstyrene, and vinyltoluene. Group monomers: Acrylic acid or methacrylic acid amide compounds; Nitrile compounds such as acrylonitrile and methacrylonitrile; Olefin compounds such as ethylene, propylene, butylene, and isoprene: ethyl vinyl ether, imbutyl vinyl ether, butyl vinyl ether, cyclohexyl vinyl ether, phenyl vinyl ether , vinyl or allyl ether compounds such as benzyl vinyl ether:
Examples include vinyl or propenyl esters such as vinyl acetate, vinyl lactate, vinyl butyrate, and isopropenyl acetate.

The resin (A) has an acid value of 40 to 150, preferably 50 to 1.
It has a range of 20. If the acid value is lower than 40, the stability of the coating composition will deteriorate, while if the acid value is higher than 150, the water resistance, alkali resistance, etc. of the coating film will deteriorate, which is not preferred.

The base resin (B) used in the composition of the present invention has an acid value lower than that of the resin (A) described above, and the difference therebetween is at least 4.
0, preferably at least 60. The resin (B) is preferably a fluororesin or a vinyl resin.

The fluororesin and vinyl resin may contain, for example, tribasic acid anhydride or ethylenically unsaturated so that the acid value of the fluororesin and vinyl resin described in the resin (A) falls within the above range. 6 obtained by adjusting the blending amount of a compound imparting an acid value such as carboxylic acid can be preferably used.

If the difference in acid value between resin (B) and resin (A) is less than 40, it will be difficult to obtain a matte coating (approximately 30 or less in 60 degree specular reflectance). If it spreads too much, the compatibility between these resins will become poor, and the stability of the coating composition will tend to deteriorate. Preferably a maximum of 120 is preferred.

Resin (A) and resin (B) each have about 2000 to 1
00,000, preferably having a number average molecular weight in the range of about 5,000 to 80,000.
If it is less than 00, the matting effect of the coating film tends to be reduced, and the weather resistance, water resistance, etc. of the coating film may also be reduced. On the other hand, if the molecular weight is greater than about 100,000, the melt flow properties of the electrolyte coating film during baking may deteriorate, resulting in a matte coating film with poor smoothness, which is not preferable.

Further, if both the resin (A) and the resin (B) are used, either one of them can have a hydroxyl group.

The content of hydroxyl groups in these resins is about 20 to 200. Preferably, the range is 30 to 150.

The blending ratio of resin (A) and resin (B) is 30 to 90% by weight of resin (A), preferably 45 to 85% by weight, and 10 to 70% by weight of resin (B) based on the total amount of both resins.
, preferably in the range of 15 to 55% by weight. ? ! If the blending ratio of 1 resin (A) is less than 30% by weight and the blending ratio of resin (B) is greater than 70% by weight, the stability of the paint will decrease and a sufficient matte coating film will not be obtained. There are drawbacks. On the other hand, if the blending ratio of resin (A) is more than 90% by weight and the blending ratio of resin (B) is less than 10% by weight, a sufficient matte coating film will not be obtained, and the water resistance of the coating film will also decrease. This is not desirable.

As the crosslinking agent used in the composition of the present invention, conventionally known amino resins, block polyisocyanate compounds, and the like can be used. As the amine resin, formaldehyde adducts of melamine resins, benzoguanamine resins, urea resins, or mixtures thereof, and alcohol etherification products thereof can be used. Blocked polyisocyanate is a polyisocyanate compound reacted with a blocking agent (e.g., alcohol, phenol, etc.), and includes ``tolylene diisocyanate as an isocyanate compound''+4.4'-diphenylmethane diisocyanate, xylylene diisocyanate, Meta-xylylene diisocyanate, hexamethylene diisocyanate, lysine diisocyanate, 4,4'-methylenebis(cyclohexyl isocyanate), methylcyclohexane 2
．． Examples include 4(2,6) diisocyanate, 1,3-(incyanatomethyl)cyclohexane, inphorone diisocyanate, trimethylhexamethylene diisocyanate, and the like.

The above-mentioned amino resin and block polyisocyanate may be used alone or in combination, and the amount used is 50% by weight or less in terms of resin solid content.

In the composition of the present invention, for example, the crosslinking agent is added to a resin solution prepared by dissolving resin (A) and resin (B) in an organic solvent before or after neutralization with a neutralizing agent, and the crosslinking agent is added to the neutralizing agent. In some cases, it can be obtained by neutralizing with a neutralizing agent and then dispersing it in water.

As the organic solvent, it is preferable to use a hydrophilic organic solvent that can dissolve and disperse the resin and crosslinking agent. Specifically, alcohols such as methyl alcohol, ethyl alcohol, isopropyl alcohol, and butyl alcohol are used. Cellosolve solvents such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, propylene glycol ethers, diethylene glycol ethers, etc. can be used.

Further, as the neutralizing agent, conventionally known basic compounds can be used, such as ammonia, dimethylamine, trimethylamine, diethylamine, triethylamine, diisopropylamine, butylamine, monoethanolamine, jetanolamine, triethanolamine. , monoisopropanolamine, diisopropanolamine, triisopropanolamine, N-methylethanolamine, N-aminoethylethanolamine,
Examples include N-methyljetanolamine and polyglycolamine. These neutralizing agents can be used in an amount of about 0.3 to 1.2 equivalents based on the carboxyl groups of the resin (A) and the resin (B).

The composition of the present invention may contain coloring pigments, extender pigments,
It may contain a coating surface conditioner and the like.

The composition of the present invention typically has a resin solids content of about 3 to 20% by weight;
It is preferably prepared in a range of about 5 to 15% by weight and used for electrocoating.

As the method and apparatus for coating using the composition of the present invention, methods and apparatus known per se that have been conventionally used in anodic coating can be used. The coating conditions used are generally a bath temperature of 20-30℃,
Voltage 100-400■ (preferably 100-300V)
, It is preferable to electrodeposit with a current application time of 30 seconds to 10 minutes.
The coating dry film thickness is usually about 2 to 50F, preferably about 5F.
~30F seems to be sufficient.

The objects to be coated by electrodeposition include conductive materials such as iron, steel, copper, aluminum, plated steel plates with zinc, tin, chromium, aluminum, etc. plated on the surface of the steel, and chromic acid coated on the surface of the steel. , metal materials that have been chemically or electrolytically treated with phosphoric acid or the like. Among them, various shapes of aluminum subjected to anodizing treatment (
For example, it is a plate-shaped, rod-shaped, enamel-shaped article, etc.

After the electrodeposited coating film formed on the object to be coated is lifted out of the lt@ bath, the amount of iron is removed from the excess paint deposited on the coating film.
Usually about 150-220°C, preferably about 16°C, without washing or washing with water or reverse osmosis water
At 0-200°C for about 10-60 minutes, preferably about 20-60 minutes
Bake for 40 minutes.

[Actions and Effects of the Invention] Generally, a mixture of two types of resins with poor compatibility is electrolyzed!
A matte coating film can be obtained by using it as a base resin for paints, but if you try to obtain a low gloss coating film, the coating stability will be poor, and if you try to improve the coating stability, you will get a low gloss coating film. Therefore, it is difficult to satisfy the performance of both.

In the composition of the present invention, a resin (
When a mixed resin of A) and a resin (B) having an acid value smaller than the acid value of the resin by a specific range is water-dispersed, the resin (A) becomes a fraction of the resin (B). It is presumed that it exhibits excellent stability and performance. On the other hand, the reason why this product forms a low-gloss coating is that when the electricity deposited on the surface of the object is heated, the coating melts and flows, forming a smooth and glossy coating. It is presumed that phase separation between the resin (A) component and the resin (B) component occurs afterwards, forming a low-gloss coating film.

The present invention will now be described in more detail. "Part" and "1%" in the examples are based on weight.

Resin A-1 Production Example Hydroxybutyl vinyl ether 10 in an autoclave
After charging 2 parts, 60 parts of diglyme, 180 parts of i-propanol, and 1M1 of N-dimethylbenzylamine, and replacing the space with nitrogen.

137 parts of chlorotrifluoroethylene was added and heated to 65°C.

Next, 40 parts of a mixture of diglyme/1-propanol (1/1 by weight) in which 2.5 parts of azobisisobutyronitrile was dissolved was added to initiate polymerization. The temperature was maintained for 20 hours with stirring. 519 parts of varnish with a solid content of 46% was obtained.

The solvent was removed by reducing the pressure while heating the varnish to 60 to 80°C.

Next, 91 parts of 1,2-cyclohexanedicarboxylic anhydride and 1 ooy of zirconium naphthenate were added to the varnish while stirring, and the mixture was reacted for 5 hours while heating to reflux the acetone. The fluorine-containing copolymer had a hydroxyl value of 50, an acid value of 100, and a number average molecular weight of 30,000.

Resin A-2 Production Example: Pour 65 parts of isopropyl alcohol into a reaction vessel.
15 parts of styrene, 30 parts of methyl methacrylate, 32.2 parts of n-butyl acrylate, 2-
10 parts of hydroxyethyl acrylate, 12 parts of acrylic acid
．． A mixture of 8 parts of azobisisobutyronitrile and 1.0 parts of azobisisobutyronitrile was added dropwise over 3 hours, and the mixture was further maintained at the same temperature for 3 hours to obtain a copolymer solution with a solid content of 60%. The acrylic copolymer had a number average molecular weight of about 30,000, a hydroxyl value of 50, and an acid value of 100.

Resin B-1 Production Example In Resin A-1 Production Example, 102 parts of hydroxybutyl vinyl ether was replaced with 41 parts of hydroxybutyl vinyl ether and 115 parts of cyclohexyl vinyl ether, 137 parts of chlorotrifluoroethylene was replaced with 165 parts, and 1.2-
It was produced using the same formulation and method as Resin A-1, except that 91 parts of cyclohexanedicarboxylic anhydride was replaced with 9 parts.

The fluorine-containing copolymer had a hydroxyl value of 50 and an acid value of 10.

Resin B-21R Example In Resin A-1 Production Example, the blending ratio of monomers was 15 parts of styrene, 30 parts of methyl methacrylate, 43.7 parts of n-butyl acrylate, 10 parts of 2-hydroxyethyl acrylate, and 1.3 parts of acrylic acid. Resin A except for
Produced using the same formulation and method as -l. The acrylic copolymer had a number average molecular weight of about 30,000, a hydroxyl value of 50, and an acid value of 10.

Resin B-3 Production Example In Resin A-1 Production Example, n-butyl acrylate 32
．． 2 parts to 39.8 parts, 12.8 parts of acrylic acid to 5.2 parts
It was manufactured using the same formulation and method as Resin A-1, except that 10% was changed. The acrylic copolymer has a number average molecular weight of about 3000.
0, hydroxyl value 50, and acid value 40.

Example 1 Triethylamine (neutralizing agent, neutralization equivalent: 0.8) was added to a mixture of 35 parts of resin A-1 and 35 parts of resin B-1, and furan 620 (manufactured by Hitachi Chemical Co., Ltd., trade name: , methyl methylolated melamine resin, solid content 70%)
42.8 parts were added and mixed well to make it homogeneous. First, deionized water was added to the mixture to obtain a solid content of 10%. Example 1
of paint was obtained.

Examples 2 to 5 A mixture of Resin A and Resin B shown in Table 1 was prepared in the same manner as in Example 1, and a neutralizing agent and deionized water were added to give a solid content of 10%.
Paints of Examples 2 to 5 were obtained.

Comparative Example 1 A mixture of Resin B-2 and Resin B-3 shown in Table 1 was mixed with a neutralizing agent and deionized water in the same manner as in Example 1 to form a comparative paint with a solid content of 10%. Obtained.

A 6063S aluminum alloy plate subjected to alumite treatment (anodized film thickness: 10 μm) was used as the paint bath of the above examples and comparative examples, and the object to be coated (anode) was a temperature source of 22° C. and a voltage of 150 μm. Electricity is applied for 3 minutes to form a film of electrodeposition paint on the object to be coated, followed by washing with water.
After baking at 0°C for 30 minutes, it was subjected to a test.

Paint storage stability: After being left in a sealed state at 30°C for 2 months, electrodeposition coating was performed and changes in the appearance of the paint film were observed by comparing the appearance with the initial paint film appearance.

Painted surface smoothness: The appearance of the painted film after painting was observed with the naked eye to check for citrus skin, pinholes, unevenness, and appearance.

Gloss: Gloss meter (VG-2PD manufactured by Nippon Denshoku Industries Co., Ltd.)
The 60° specular reflectance (unit: %) was measured using the following.

Goban adhesion: Make 100 1 mm square creases in the coating film with a cutter knife, and cut 100 creases with cellophane adhesive tape.
A peel test was conducted to determine the number of remaining folds.

Alkali resistance: After being immersed in a 3% by weight aqueous solution of sodium hydroxide for 72 hours, the appearance of the coating film was visually observed to determine the presence or absence of blistering.

(O: No abnormality, O: Slight blistering, Δni blistering, ×: Significant blistering) Weather resistance: Weather meter (manufactured by Suga Test Instruments Co., Ltd., Ducycle, 60 minutes of irradiation/60 minutes of darkness, black An accelerated weathering test was conducted for 240 hours at a panel temperature of 63°C.
Gloss retention (unit: %) and appearance were measured.

Claims (1)

[Claims] 1. Contains a base resin and a crosslinking agent as essential components, the base resin is a mixture of resin (A) and resin (B),
At least one of these resins (A) and resin (B) is a fluorine-containing resin, and the acid value of the resin (A) is 40.
~150, an anionic matte electrodeposition coating composition characterized in that the acid value of the resin (B) is lower than the acid value of the resin (A), and the difference therebetween is at least 40.