JPH0762278A - Resin composition for electrodeposition coating - Google Patents

Abstract

PURPOSE:To obtain the subject composition excellent in low-temperature curability and stability with the lapse of time, suitable for construction materials, etc., by neutralizing with an organic amine a polymer made from a specific phosphoric ester monomer, etc., and an alkoxylated methylolmelamine resin followed by addition of water into an emulsion. CONSTITUTION:The objective composition can be obtained by partially neutralizing with an organic amine such as monomethylamine (A) a total of 100 pts.wt. of a polymer made from (1) 2.5-10 pts.wt. of an alpha,beta-ethylenically unsaturated carboxylic acid monomer, (2) 0.4-25 pts.wt. of an alpha,beta-ethylenically unsaturated carboxylic hydroxyalkyl-contg. ester monomer, (3) 57-97 pts.wt. of another comonomer and (4) 0.1-8 pts.wt. of a phosphoric ester monomer having one copolymerizable double bond, of the formula (R1 and R2 are each H or methyl; R3 is H or alkyl; n is 2-10) and (B) an alkoxylated methylolmelamine resin followed by addition of water into an emulsion.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low temperature curable resin composition for electrodeposition coating, and more particularly to a resin composition for electrodeposition coating which is most suitable for aluminum building materials.

[0002]

2. Description of the Related Art Conventionally, as an electrodeposition coating material for coating aluminum materials, an acrylic copolymer obtained by copolymerizing (meth) acrylic acid and other acrylic monomers is used as a melamine resin. Water-soluble or water-dispersible paints containing various amino resins have been used and have been put to practical use in building materials such as aluminum sashes or curtain walls for general houses and high-rise buildings, but in recent years,
In electrodeposition coating, a coating having a matte appearance or a white appearance has been widely used.

Recently, due to the demands of the times, low temperature curability has been emphasized in order to improve productivity. However, curing of a coating film formed from a conventional coating material that has been put into practical use still requires baking at a high temperature of 170 to 180 ° C., which causes a large economical loss and cannot improve productivity. is there. Conventionally, as a monomer component of the above-mentioned acrylic copolymer, a water-soluble electrodeposition coating composition in which phosphoric acid having a copolymerizable double bond or a phosphorous acid group-containing monomer is copolymerized (Japanese Patent Publication No. 49-10360).
Issue).

[0004]

The above-mentioned known water-soluble electrodeposition coating composition has a low-temperature curable function, but if the electrodeposition solution is left unattended, the electrodeposition solution formed from the electrodeposition solution becomes lapsed over time. There is a drawback that the appearance of the electrodeposition coating film is deteriorated and the electrodeposition liquid performance becomes an abnormal electrodeposition coating film and deteriorates with time.

The present invention overcomes the above-mentioned drawbacks of conventional electrodeposition coating compositions, and provides a resin composition for electrodeposition coating compositions which has a low temperature cross-linking property of the electrodeposition coating composition and stability of the electrodeposition liquid over time. Has an aim.

[0006]

[Means for Solving the Problems] In order to achieve the above object, the inventors of the present invention have conducted extensive studies, and as a result, have found that a monomer having an α, β-ethylenically unsaturated double bond and a copolymerizable diamine A resin composition for electrodeposition coating containing a copolymer of a specific phosphoric acid ester monomer having a heavy bond and an alkoxylated methylol melamine resin as a main component has good low-temperature curability of the electrodeposition coating film, and also electrodeposition. The present invention has been completed based on the finding that the stability of the liquid over time is also good.

That is, the present invention comprises (a) 2.5 to 10 parts by weight of an α, β-ethylenically unsaturated carboxylic acid monomer and (b) a hydroxyalkyl-containing ester of an α, β-ethylenically unsaturated carboxylic acid. 0.4 to 25 parts by weight of monomer, (c) 57 to 97 parts by weight of other copolymerizable monomer, and (d) phosphate ester monomer having one copolymerizable double bond. The polymer [A] and the alkoxylated methylol melamine resin (B) consisting of 1 to 8 parts by weight and the total amount of 100 parts by weight are the main components for forming a coating film, and the components [A] and [B] are organic amines. After partially neutralizing with
In the composition in which water is added to form an emulsion, the phosphate ester monomer having one copolymerizable double bond, which is the component (d) of the copolymer [A], has the following general formula 1

Embedded image (wherein R ₁ , R _{2 is} hydrogen or a methyl group, R _{3 is} hydrogen or an alkyl group, n: 2 to 10) and is a phosphoric acid ester monomer. The main point is a resin composition.

[0008]

The structure and operation of the present invention will be described in more detail. In the present invention, (a) α, β-ethylenically unsaturated carboxylic acid monomer and (b) hydroxyalkyl-containing ester monomer of α, β-ethylenically unsaturated carboxylic acid and (c) other copolymerization Of a polymerizable monomer and (d) a phosphoric ester monomer having one copolymerizable double bond of the following general formula 1 and an alkoxylated methylol melamine resin (B) As a main component for formation, a composition in which the components [A] and [B] are partially neutralized with an organic amine and then water is added to form an emulsion is an essential component.

[0009]

[Chemical 1]

First, as the α, β-ethylenically unsaturated carboxylic acid monomer of the component (a) of the present invention, acrylic acid and α
-Chloroacrylic acid, methacrylic acid, itaconic acid, maleic anhydride, maleic acid, fumaric acid, crotonic acid, citraconic acid, mesaconic acid, etc., alone or in mixture, or their functional derivatives having at least one carboxyl group, such as These include partial esters or amides of saturated, polymerizable di- or poly-carboxylic acids.

Next, as the hydroxyalkyl-containing ester monomer of the α, β-ethylenically unsaturated carboxylic acid as the component (b), 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2 -Hydroxypropyl methacrylate, 3-hydroxypropyl acrylate, 3-hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate, diethylene glycol monoacrylate, diethylene glycol monomethacrylate and the like.

Examples of the other copolymerizable monomer as the component (c) include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate and n.
-Propyl acrylate, n-propyl methacrylate, isopropyl acrylate, isopropyl methacrylate, butyl acrylate, butyl methacrylate,
There are lauryl acrylate, lauryl methacrylate, stearyl acrylate, stearyl methacrylate, hexyl acrylate, 2-ethylhexyl methacrylate, heptyl acrylate, heptyl methacrylate, and the like, and similar esters having up to about 20 carbon atoms in the alkyl group can be used. In addition, styrene, α-
Examples include alkyl styrene, α-chlorostyrene, vinyltoluene, acrylonitrile, vinyl acetate and the like.

The component (d) used in the present invention as the phosphoric acid ester monomer having one polymerizable double bond is acid phosphooxypolyoxyethylene glycol monomethacrylate (ethylene oxide: 4 to 4).
5 mol), acid phosphooxypolyoxypropylene glycol monomethacrylate (propylene oxide: 5 to 6 mol) and the like.

Next, as the alkoxylated methylol melamine resin as the component [B], at least a part of the methylol group may be alkoxylated with a lower alcohol. As the lower alcohol, methyl alcohol,
Use one or more of ethyl alcohol, isopropyl alcohol, butyl alcohol, etc.

Next, as the organic amine, an alkylamine such as monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoisopropylamine, diisopropylamine, triisopropylamine, monobutylamine, dibutylamine, tributylamine, etc. , Monoethanolamine, diethanolamine, triethanolamine, mono (2-hydroxypropyl) amine, di (2-
Alkanolamines such as hydroxypropyl) amine, tri (2-hydroxypropyl) amine, dimethylaminoethanol and diethylaminoethanol, alkylenepolyamines such as ethylenediamine, propylenediamine, diethylenetriamine and triethylenetetramine, alkylenes such as ethyleneimine and propyleneimine Examples include imines, piperazine, morpholine, pyrazine and pyridine.

Constituting the copolymer [A] of the present invention (d)
The phosphoric acid ester monomer having one copolymerizable double bond, which is a component, is 0.
If it is less than 1 part by weight, the low temperature curability will be poor, and if it exceeds 8.0 parts by weight, the water resistance of the electrodeposition coating film will be deteriorated.

If the amount of the α, β-ethylenically unsaturated carboxylic acid monomer as the component (a) is less than 2.5 parts by weight in 100 parts by weight of the component [A], the water dispersibility becomes poor. 1
If it exceeds 0 parts by weight, the coating performance such as water resistance is deteriorated.

If the hydroxyalkyl-containing ester monomer of the α, β-ethylenically unsaturated carboxylic acid of the component (b) is less than 0.4 parts by weight in 100 parts by weight of the component [A] of the copolymer, the temperature is low. There is no effect on the curability, and if it exceeds 25 parts by weight, the coating film performance deteriorates.

The alkoxylated methylolmelamine resin as the component [B] is used in an amount of 50 to 95 parts by weight of the component [A].
50 to 5 parts by weight is preferable. When the amount of the component (B) exceeds 50 parts by weight, the stability of the electrodeposition liquid is lowered, and when it is less than 5 parts by weight, the coating film performance is lowered.

[0020]

EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples of the present invention, but the present invention is not limited thereto. The parts in the production examples, examples, comparative examples and applied reference examples are parts by weight unless otherwise specified.

Example 1 3000 ml equipped with stirrer, thermometer and reflux condenser
Acrylic acid 4 parts, 2-hydroxyethyl methacrylate 15 parts, styrene 15 parts, octyl acrylate 15 parts, ethyl acrylate 10 parts, methyl methacrylate 33 parts, and acid phosphooxypolyoxypropylene glycol monomethacrylate as a phosphoric acid-containing monomer in a flask. (Hosmer PP, manufactured by Uni Chemical Co., Ltd.)
Charge 8 parts, 1.5 parts of azobisisobutyronitrile, 12 parts of ethylene glycol monobutyl ether and 35 parts of isopropyl alcohol, and stir under reflux for 6 hours.
An α, β-ethylenically unsaturated polycarboxylic sun resin solution was prepared.

Next, the polycarboxylic acid resin liquid 120 is placed in a container.
Parts, mixed alkyl etherified methylol melamine resin 2
0 parts, ethylene glycol monobutyl ether and triethylamine were added and sufficiently stirred. Further, deionized water was added with stirring to prepare an electrodeposition resin solution having a resin solid content of 8% by weight.

Example 2 In the same manner as in Example 1, 3 parts of acrylic acid in the polycarboxylic acid resin, 10 parts of 2-hydroxyethyl methacrylate, 44 parts of methyl methacrylate, and acid phosphooxypolyoxy as the phosphoric acid-containing monomer were used. Propylene glycol monomethacrylate (Phosmer PP, manufactured by Unichemical Co., Ltd.) was changed to 3 parts, polycarboxylic acid resin was changed to 110 parts, and mixed alkyl etherified methylol melamine resin was changed to 25 parts.
An electrodeposition paint having a resin solid content of 8% by weight was prepared.

Example 3 In the same manner as in Example 1, 5 parts of acrylic acid in the polycarboxylic acid resin, 17 parts of 2-hydroxyethyl methacrylate, 37 parts of methyl methacrylate, and acid phosphooxypolyoxy were used as phosphoric acid-containing monomers. The same procedure was repeated except that 1 part of ethylene glycol monomethacrylate (Phosmer PE, manufactured by Unichemical Co., Ltd.) was used, and 120 parts of polyoxycarboxylic acid resin and 20 parts of mixed alkyl etherified methylol melamine resin were used. An electrodeposition paint of 8% by weight was prepared.

Comparative Example 1 The same method as in Example 1 was repeated except that acrylic acid was changed to 5 parts, methyl methacrylate was changed to 40 parts, and phosphoric acid-containing monomer was changed to 0 part, and the resin solid content was 8% by weight.
The electrodeposition paint of was adjusted.

Comparative Example 2 In the same manner as in Example 1, 5 parts of acrylic acid, 2-
10 parts of hydroxyethyl methacrylate, 44.95 parts of methyl methacrylate, and 0.05 parts of acid phosphooxypolyoxypropylene glycol monomethacrylate (Phosmer PP, manufactured by Unichemical Co., Ltd.) as the phosphoric acid-containing monomer were added to the polycarboxylic acid resin 104. Department,
The same procedure was repeated except that 30 parts of the mixed alkyl etherified methylol melamine resin was used.
A weight percent electrodeposition coating was prepared.

Comparative Example 3 In the same manner as in Example 1, 4 parts of acrylic acid, 42 parts of methyl methacrylate, 5 parts of 2-hydroxyethyl methacrylate, and acid phosphooxypolyoxyethylene glycol monomethacrylate (phosmer) were used as phosphoric acid-containing monomers. (PE, manufactured by Unichemical Co., Ltd.) except that 9 parts, polycarboxylic acid resin 120 parts, mixed alkyl etherified methylol melamine resin 20 parts were used, and the same procedure was followed to obtain an electrodeposition paint having a resin solid content of 8% by weight. It was adjusted.

Comparative Example 4 71 parts (0.5 mol) of phosphoric anhydride was placed in a fully dried reactor.
Was charged, and 130 parts (1 mol) of sufficiently dehydrated 2-hydroxyethyl methacrylate was added over 3 hours. During this operation, stirring was performed while maintaining the reaction temperature at 50 to 60 ° C. After further stirring at this temperature for 1 hour, water 9
Parts (0.5 mol) were gradually added and the reaction was terminated by keeping at this temperature for 1 hour. The phosphoric acid monoester of 2-hydroxyethyl methacrylate thus obtained was a pale yellow transparent liquid and had an acid value of 540.

Then, 100 parts of ethylene glycol monoethyl ether was charged into a reactor and heated to 80 ° C. in a water bath, to which 45 parts of butyl acrylate, 10 parts of methyl methacrylate, 30 parts of styrene, 5 parts of N-methylol acrylamide, the above were added. 10 parts of phosphoric acid monoester of 2-hydroxyethyl methacrylate obtained as above, 3 parts of azobisisobutyronitrile, 20 parts of isopropanol
The mixture of parts is added dropwise over 3 hours, and then heated and stirred for 4 hours. Then, the mixture was cooled to 50 ° C., 8 parts of triethylamine was added, and the mixture was stirred.
A weight percent electrodeposition coating was prepared.

Application Example 1 Using the electrodeposition coating solutions prepared in Examples 1 to 3 and Comparative Examples 1 to 4, an anodized aluminum plate was used as an anode and an 18-8 stainless steel plate was used as a cathode according to a conventional method. A DC voltage of 180 V was applied between both electrodes for 2 minutes. Then, the aluminum plate coated with electrodeposition was taken out, washed thoroughly with water, and then baked and dried at each temperature of 180 ° C., 150 ° C. and 130 ° C. for 30 minutes. As a result, the characteristics of the electrodeposition coating film formed on each aluminum plate were as shown in Tables 1, 2 and 3.

[0031]

[Table 1]

[0032]

[Table 2]

[0033]

[Table 3]

Application Example 2 The electrodeposition coating solutions prepared in Example 1 and Comparative Example 4 were left for 1 day and 14 days, and then electrodeposition coating and baking drying were carried out in the same manner as in Application Example 1. As a result, the characteristics of the electrodeposition coating film formed on each aluminum plate were as shown in Tables 4, 5, and 6.

[0035]

[Table 4]

[0036]

[Table 5]

[0037]

[Table 6]

The test methods for each item of coating film physical properties in Table 1, Table 2, Table 3, Table 4, Table 5, and Table 6 are as follows. 1. The coating thickness is based on Permascope E-110B (manufactured by Fisher). 2. The pencil hardness is based on the pencil scratch test of (JIS H-8602). 3. The adhesiveness is based on the adhesiveness test of (JIS H-8602). 4. The solvent resistance is indicated by the number of times the coating film is scratched by rubbing with MEK. 5. The boiling water resistance is 10 according to JIS H-8602.
It was immersed at 0 ° C. for 5 hours, and the gloss retention rate (%) before and after the immersion was shown.

[0039]

EFFECTS OF THE INVENTION Since the present invention is constituted as described above, the electrodeposition coating film using the coating resin composition of the present invention has good low temperature curability, and the electrodeposition coating solution is stable over time. Is good and extremely useful in industry.

Claims (1)

[Claims] (1) 2.5 to 10 parts by weight of α, β-ethylenically unsaturated carboxylic acid monomer and (b) hydroxyalkyl-containing ester monomer of α, β-ethylenically unsaturated carboxylic acid 0.4 to 25 parts by weight and (c) 57 to 97 parts by weight of other copolymerizable monomer and (d) 0.1 to 8 of phosphate ester monomer having one copolymerizable double bond. The polymer [A] and the alkoxylated methylol melamine resin (B), which are made up of 100 parts by weight and have a total amount of 100 parts by weight, are the main components for forming a coating film. In a composition in which water is added to form an emulsion after neutralization, the phosphate ester monomer having one copolymerizable double bond, which is the component (d) of the copolymer [A], is General formula 1 of (Wherein, R _1, R _2: hydrogen or a methyl group R _3: hydrogen or an alkyl radical n: 2 to 10) electrodeposition coating resin composition, which is a phosphoric acid ester monomer represented by.