JP2001342425A - Anionic electrodeposition coating and electrodeposition coating method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an anionic electrondeposition coating excellent in scuff resistance, and especially having such coating appearance and coating performance as suitably applicable to an aluminum material, and to provide an electrondeposition coating method therefor. SOLUTION: This anionic electrondeposition coating comprises (A) a vinyl copolymer having an acid value of 10-150 and a hydroxyl value of 20-200, (B) an amino resin, and (C) rigid resin fine particles which are mainly composed of methyl methacrylate or styrene, wherein the vinyl copolymer is obtained by copolymerizing an α,β-ethylenic unsaturated carboxylic acid monomer, an hydroxyl group-containing α,β-ethylenic unsaturated monomer, and the other α,β-ethylenic unsaturated monomer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anionic electrodeposition coating and a method of electrodeposition coating. More specifically, it is characterized by being able to provide a coating film having excellent scratch resistance, and is particularly suitable for coating an aluminum material.

[0002]

2. Description of the Related Art Anodized aluminum materials are widely used in building materials such as window frames, doors, and exteriors of buildings and houses because of their light weight, high strength, and excellent corrosion resistance. For the coating of aluminum material, an anionic electrodeposition paint having a good finish with one coat is generally used. A typical example of the anion type electrodeposition paint is a melamine curing type electrodeposition paint obtained by mixing a water-soluble acrylic resin containing a carboxyl group and a hydroxyl group with a melamine resin cross-linking agent and dispersing in water. Painting and matte-type painting.

[0003]

However, when coating a conventional anion-type electrodeposition paint, for example, when packing an aluminum sash with a packing material such as cardboard, or when transporting the packed paint, There has been a problem that the film and the packing material are rubbed and the coating film is scratched, thereby lowering the commercial value.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above problems, and as a result, blended hard resin fine particles with an anionic electrodeposition paint based on a specific vinyl copolymer. As a result, an anion-type electrodeposition paint having excellent scratch resistance and a method for applying the same were successfully established, and the present invention was completed.

That is, the present invention relates to (A) an α, β-ethylenically unsaturated carboxylic acid monomer, a hydroxyl group-containing α, β-ethylenically unsaturated monomer, and another α, β-ethylenically unsaturated monomer. Acid value 10-150, hydroxyl value 20
And (B) an amino resin and (C) hard resin fine particles containing methyl methacrylate or styrene as main components.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the electrodeposition paint of the present invention and the electrodeposition coating method thereof will be described in detail.

[(A) Vinyl Copolymer] The α, β-ethylenically unsaturated carboxylic acid monomer in the (A) vinyl copolymer used in the present invention is water-dispersible in the vinyl copolymer. To impart electrophoretic properties. Examples include acrylic acid, methacrylic acid, crotonic acid, vinyl acetic acid, itaconic acid, maleic acid, maleic anhydride, fumaric acid, citraconic acid, and the like. These may be used alone or in combination of two or more.

The amount of the α, β-ethylenically unsaturated carboxylic acid monomer used is preferably such that the acid value in the vinyl copolymer is 1
It is used in the range of 0 to 150, more preferably 20 to 100. If the acid value of the vinyl copolymer is less than 10, it is difficult to obtain sufficient water dispersion stability, and if it exceeds 150, the electrophoretic property and the deposition property of the coating film are reduced, and the water resistance and alkali resistance of the coating film are reduced. .

The hydroxyl group-containing α, β-ethylenically unsaturated monomer reacts with a melamine resin to impart curability when the coating film is baked. For example, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate,
2-hydroxypropyl methacrylate, 4-hydroxybutyl acrylate, 4-hydroxybutyl methacrylate, diethylene glycol monoacrylate, diethylene glycol monomethacrylate, and the like, and modified lactones thereof, may be used alone or in combination of two or more. it can.

The hydroxyl group-containing α, β-ethylenically unsaturated monomer is used in such a range that the hydroxyl value in the vinyl copolymer is preferably from 20 to 200, more preferably from 40 to 160. . If the hydroxyl value is less than 20, sufficient curability is not ensured, and if it exceeds 200, the coating film becomes brittle, the water resistance is reduced, and it is difficult to obtain sufficient performance.

As the other α, β-ethylenically unsaturated monomers, alkyl esters of acrylic acid or methacrylic acid, or other vinyl monomers and amide monomers can be used. Specific examples of the compound include 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, heptyl acrylate,
Alkyl ester of acrylic acid or methacrylic acid such as heptyl methacrylate, styrene, α-methylstyrene, vinyltoluene, vinyl acetate, acrylonitrile,
Examples include amide monomers such as vinyl monomers such as methacrylonitrile, acrylamide, methacrylamide, methylolacrylamide, methylolmethacrylamide, methoxymethylacrylamide, n-butoxymethylacrylamide, diacetoneacrylamide, and diacetonemethacrylamide. . These can be used alone or in combination of two or more.

Further, the α, β-ethylenically unsaturated monomer having a cross-linking functional group according to claim 2 or 3 forms a stable insoluble microgel in a vinyl copolymer, and has a matting performance. Is given. For example, acetoacetoxyethyl acrylate, acetoacetoxyethyl methacrylate, γ-acryloxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-acryloxypropyltriethoxysilane, γ-methacryloxypropyltriethoxysilane , Β-methyl-substituted glycidyl acrylate, β-
Methyl-substituted glycidyl methacrylate and the like are used, and after water dispersion by a method described later, a microgel is generated in dispersed particles to reduce gloss. In particular, acetoacetoxyethyl acrylate and acetoacetoxyethyl methacrylate are preferred because the use of formaldehyde promotes the formation of a microgel.

The preferred weight average molecular weight of the vinyl copolymer is from 10,000 to 100,000, more preferably from 20,000 to 70,000. When the weight average molecular weight is 10,000 or less, the coating film durability is not sufficiently obtained, and when it is 100,000 or more, water dispersibility decreases and the handling property of the coating becomes poor.

The vinyl copolymer as described above can be obtained by polymerizing the above monomers by a known method such as solution polymerization, non-aqueous dispersion polymerization, bulk polymerization, emulsion polymerization, suspension polymerization and the like. Particularly, solution polymerization is preferable, and the reaction temperature is usually selected from 40 to 170 ° C.

As a reaction solvent, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol,
Isobutyl alcohol, sec-butyl alcohol, t
-It is preferable to use a hydrophilic solvent such as butyl alcohol, methyl cellosolve, ethyl cellosolve, propyl cellosolve, butyl cellosolve, propylene glycol monomethyl ether, propylene glycol monoethyl ether, and propylene glycol monobutyl ether. Known polymerization initiators such as organic peroxides, azo compounds, ammonium persulfate, and potassium persulfate can be used as the polymerization initiator.

In order to disperse the obtained vinyl copolymer in water, at least a part of the carboxyl groups in the vinyl copolymer is neutralized with a basic substance such as an organic amine or an inorganic base. Examples of such basic substances include alkylamines such as monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoisopropylamine, diisopropylamine, triisopropylamine, monobutylamine, dibutylamine, and tributylamine, diethanolamine, diisopropanol Amines, triethanolamine, dimethylethanolamine, alkanolamines such as diethylethanolamine, ethylenediamine, propylenediamine, diethylenetriamine, alkylenepolyamines such as triethylenetetramine, ammonia, ethyleneimine, pyrrolidine, piperidine, piperazine,
Examples include morpholine, sodium hydroxide, potassium hydroxide and the like. The neutralization rate with such a basic substance is 30 to
Although 120% is suitable, it is particularly preferably 50% to 100% since the water dispersibility is good and gloss unevenness does not occur.

[(B) Amino Resin] As the (B) amino resin used in the present invention, conventionally known melamine resins, benzoguanamine resins, urea resins and the like can be mentioned. Of these, preferred are methylol groups. Is an alkyl etherified methylol melamine resin obtained by alkoxylating at least a part of the above with a lower alcohol. As the lower alcohol, one or more of methyl alcohol, ethyl alcohol, propyl alcohol, butyl alcohol and the like can be used. There is no problem even if one kind of melamine resin is used or two or more kinds of melamine resins are combined.

Examples of the alkyl etherified methylol melamine resin include Cymel 2 manufactured by Mitsui Cytec Co., Ltd.
66, 232, 235, 238, 236, My Court 5
06, 508, Sumimar M- manufactured by Sumitomo Chemical Co., Ltd.
66B, Nikarac MX-4 manufactured by Sanwa Chemical Co., Ltd.
0, MX-45, etc., but are not limited thereto.

The preferred range of the amount of the amino resin (B) used in the present invention is 30 to 100 parts by weight based on 100 parts by weight of the vinyl copolymer (A). When the amount is less than this range, the cross-linking of the coating film is insufficient, so that the mechanical properties, solvent resistance, chemical resistance, etc. decrease, and when the amount is large, the affinity with the vinyl copolymer becomes insufficient, Problems such as poor stability of the aqueous dispersion, non-uniform dispersion particle size, poor washability after electrodeposition, water repellency, unevenness in gloss of the coating film, and opacification occur.

[(C) Hard resin fine particles containing methyl methacrylate or styrene as a main component] The hard resin fine particles containing (C) methyl methacrylate or styrene as a main component used in the present invention include methyl methacrylate or styrene as a main component. A crosslinked or uncrosslinked acrylic resin is finely pulverized, and by blending these, the abrasion resistance of the coating film is greatly improved. It is considered that the hard resin fine particles containing methyl methacrylate or styrene as a main component contribute to hardening of the coating film, and the hardening of the coating film improves the scratch resistance. The particle diameter is preferably 30 μm or less, more preferably 20 μm or less, from the viewpoint of the smoothness of the coating film and the like,
More preferably, it is 10 μm or less.

The hard resin fine particles containing methyl methacrylate or styrene as a main component of the present invention are exemplified by Chemisnow MP series (acryl fine particles) manufactured by Soken Chemical Co., Ltd.
MP-1451, MP-5000, MP-1400,
Chemisnow MR series (crosslinked acrylic fine particles) MR
-2G, MR-7G, MR-10G, MX-150, MX- of Chemisnow MX series (crosslinked acrylic fine particles)
300 and MX-1000, but are not limited to these.

The preferred range of the amount of the hard resin fine particles (C) of the present invention containing methyl methacrylate or styrene as a main component is 100 parts by weight of a mixture obtained by adding (A) a vinyl copolymer and (B) an amino resin. The amount is 1 to 30 parts by weight. If it is less than this range, the abrasion resistance is not sufficient, and if it is too large, the coating becomes unstable and aggregates and precipitates are undesirably generated.

[Electrodeposition coating method] The electrodeposition coating obtained by the present invention may be diluted with deionized water or deionized water partially containing a hydrophilic solvent, if necessary, to obtain a matte or glossy type. Used for electrodeposition coating. When performing electrodeposition coating, the solid content concentration of the coating bath is suitably from 4 to 20% by weight. When the amount is lower than 4% by weight, it takes a long time to obtain a required coating film thickness. When the amount exceeds 20% by weight, the state of the bath becomes unstable, and the amount of the paint taken out of the coating system is also large. Becomes

Regarding the coating method, the electrodeposition coating is performed using the object to be coated as an anode.
Preferably, it is 1 to 5 minutes. The higher the voltage, the shorter the energization time, and conversely, the lower the voltage, the longer the energization time. The coating voltage may be applied by applying the set voltage at the same time as energization or by gradually increasing the set voltage to the set voltage. The electrodeposited substrate is optionally washed with water, and then heated at 150 to 200 ° C. for 15 to 60 minutes to obtain a final coating film. The coating thickness is preferably from 5 to 30 μm.

The material of the object to which the electrodeposition coating method of the present invention is applied is not particularly limited as long as it has conductivity, but is preferably a material using aluminum or an aluminum alloy. In addition, the resulting coating film has excellent appearance such as smoothness and uniformity, mechanical properties, solvent resistance, chemical resistance,
It is also excellent in performance such as weather resistance.

[0026]

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. In addition, the compounding quantity in a table | surface expresses a weight part unless there is particular description.

[Production of vinyl copolymer] Production Examples 1 to 3
(Production of Resin Liquids A1 to A4) A reaction apparatus having a stirring device, a thermometer, a monomer dropping device, and a reflux cooling device is prepared. According to the composition shown in Table 1, (1) and (2) were charged into a reactor, and the temperature was raised to the reflux temperature with stirring, and (3) to
After (12) was previously mixed uniformly, it was added dropwise over 3 hours. The temperature was maintained at 90 ° C. After the completion of dropping:
After 5 hours, (13) was added, and the mixture was further added at 90 ° C for 1.5 hours.
The reaction was continued for an hour to obtain transparent and viscous resin liquids A1 to A4 having a resin solid content of 65%. The acid value, hydroxyl value and weight average molecular weight are also shown in Table 1.

[0028]

[Table 1]

[Production of Dispersed Resin Liquid and Electrodeposition Paint] A reactor having a stirrer, a thermometer and a reflux cooling device is prepared, and (1) to (8) are charged according to the composition shown in Tables 2 and 3. The mixture was stirred and mixed at 60 ° C. for 1 hour. After adding (9) to this, (10) was gradually added to obtain a dispersion resin liquid.
With respect to the dispersion resin liquids B1 and B5, (11) was further added, and the mixture was kept at 50 ° C. for 4 hours to perform a microgelation reaction. Microgels have already been formed in the dispersion resin liquids B2 and B6 as they are. Regarding the dispersed resin liquids B3 and B7,
The microgelation reaction was performed by keeping the temperature at 75 ° C. for 10 hours. Finally, (12) was added to each to prepare a dispersion resin solution having a solid content of 30%.

[0030]

[Table 2]

In the table, Cymel 238, Cymel 236,
Cymel 235 is a melamine resin manufactured by Mitsui Cytec Co., Ltd. MR-2G is a crosslinked acrylic fine particle manufactured by Soken Chemical Co., Ltd., and has a particle size of 10 μm or less.

[0032]

[Table 3]

[Production of electrodeposition paint] The above-mentioned dispersed resin liquid B1
The solid content was adjusted to 10% by adding deionized water to B8, and then the pH was adjusted to 8.0 by adding triethylamine to obtain each of the electrodeposition paints C1 to C8.

[Electrodeposition coating and evaluation of coating film performance] (Examples 1 to 6, Comparative Examples 1 and 2) The electrodeposition coatings obtained above (Examples 1 to 4 are electrodeposition coatings C1 to C4, Comparative Examples 1-4
Is placed in a bath made of vinyl chloride, the cathode is made of SUS304 steel plate, and the 6063S aluminum alloy plate is subjected to alumite treatment (alumite film thickness = 9 μm), and further electrolytically colored black, Electrodeposition coating was performed using an aluminum material washed with a conventional method as an anode (object to be coated). The specific conditions of the electrodeposition coating are as follows: bath temperature 22 ° C, distance between electrodes 12
cm, pole ratio (+/-) 2/1, and 13
A current was applied at 0 V so that the coating thickness became 10 μm, and after the completion of electrodeposition, the film was washed and subsequently baked at 185 ° C. for 30 minutes. The performance of the obtained coating film was evaluated, and the results are shown in Tables 4 and 5.

[0035]

[Table 4]

[0036]

[Table 5]

The evaluation method is as follows. (1) Gloss value: 60 ° specular reflectance was measured with a gloss meter. (2) Pencil hardness: tear determination based on JIS K-5400. (3) Adhesion: 100 grids were formed on the coating film with a cutter knife, and after sticking Cellotape (registered trademark) thereon, the adhesion was observed when the cellotape was quickly peeled off. The resulting numbers mean the following: 100/100: No peeling of the coating film. 0/100: All peeled off. (4) Alkali resistance The state of the coated surface was observed after immersion in a 1% aqueous sodium hydroxide solution at 20 ° C. for 48 hours. (5) Acid resistance: After immersing in a 5% aqueous sulfuric acid solution at 20 ° C. for 48 hours, the state of the coated surface was observed. (6) Scratch resistance: After applying a load of 10 g / cm ² to corrugated paper and rubbing 50 times back and forth with a 5 cm stroke,
The degree of scratches on the painted surface was visually evaluated. ○ = Scratch is not visible. Δ = Scratch is visible, but not as white as a sheet. × = The scar looks like a white surface. (7) Fisher scope test: Evaluated using Fisher scope H-100. The measuring method is as follows. Measurement mode is load increase → constant pressure → load decrease, initial load is 4mN, maximum load is 256mN, load increase (and decrease) is every 0.5 seconds, constant pressure is 64 seconds. Depression depth t (m) when a load P (N) = 4 mN is applied to the indenter
m), hardness = P / (26.4 × t ² ) was determined. From the maximum depression depth during measurement and the depression depth at the end of measurement,
Relative elasticity recovery rate = (maximum depression depth-depression depth at the end of measurement) / (maximum depression depth).

[0038]

EFFECT OF THE INVENTION By applying the anionic electrodeposition paint and the electrodeposition coating method of the present invention, the coating film is excellent in the appearance and performance of the coating film, and particularly excellent in the abrasion resistance due to the packing material such as corrugated cardboard. It became possible to provide. It is particularly suitable for coating an aluminum material as an object to be coated.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C09D 125/04 C09D 125/04 133/10 133/10 161/20 161/20 C25D 13/06 C25D 13 / 06 Z F term (reference) 4D075 BB89Z CA02 DA06 DB07 DC02 EA02 EB14 EB22 EB55 EB57 EC24 4J038 CC022 CF071 CG021 CG031 CG061 CG071 CG141 CG142 CH032 CH121 CJ131 CJ181 DA142 DA162 DA172 GA03 MA03 NA03 MA03 MA03 NA03

Claims (6)

[Claims] (A) An α, β-ethylenically unsaturated carboxylic acid monomer, a hydroxyl group-containing α, β-ethylenically unsaturated monomer, and other α, β-ethylenically unsaturated monomers are used. Anionic type comprising a copolymerized vinyl copolymer having an acid value of 10 to 150 and a hydroxyl value of 20 to 200, (B) an amino resin, and (C) hard resin fine particles mainly containing methyl methacrylate or styrene. Electrodeposition paint and electrodeposition coating method. 2. An essential monomer component wherein the other α, β-ethylenically unsaturated monomer of the vinyl copolymer resin (A) has an α, β-ethylenically unsaturated monomer having a crosslinking functional group. The anionic electrodeposition coating composition according to claim 1 which is contained as a component and a method for electrodeposition coating the same. 3. Other α, β of the vinyl copolymer (A)
Α, β in which the ethylenically unsaturated monomer has a crosslinking functional group
2. The anionic electrodeposition coating composition according to claim 1, wherein the composition does not contain an ethylenically unsaturated monomer as an essential monomer component. 4. The hard resin fine particles (C) containing methyl methacrylate or styrene as a main component have a particle diameter of 30 μm.
The anion-type electrodeposition paint according to any one of claims 1 to 3, and an electrodeposition coating method thereof. 5. A hard resin fine particle (C) containing methyl methacrylate or styrene as a main component has a particle diameter of 20 μm.
The anion-type electrodeposition paint according to any one of claims 1 to 3, and an electrodeposition coating method thereof. 6. A hard resin fine particle (C) containing methyl methacrylate or styrene as a main component has a particle size of 10 μm.
The anion-type electrodeposition paint according to any one of claims 1 to 3, and an electrodeposition coating method thereof.