JPH11172164A - Anode-depositing electrodeposition coating composition having excellent scratch resistance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an anode-depositing electrodeposition coating composition capable of forming a coating film having excellent scratch resistance on a metallic article made of e.g. aluminum or iron. SOLUTION: The objective composition contains colloidal silica. This electrodeposition coating composition having a solid content of 9%, pH of 8.7 and a liquid resistivity of 1,680 Ω.cm can be produced by adding 7.2 pts. of triethylamine and 160.0 pts. of deionized water to 152.4 pts. of a resin liquid containing a polycarboxylic acid under agitation, continuing the agitation for 1 hr until the mixture becomes a homogeneous liquid, adding 50.0 pts. of Nikalac MX-40 (commercial name: melamine manufactured by Sanwa Chemical Co.), heating the mixture to 80 deg.C, stirring for 2 hr, cooling to 25 deg.C, adding 1,690.0 pts. of deionized water and 321.5 pts. of Snowtex UP (commercial name: colloidal silica manufactured by Nissan Chemical Industries Co.) and stirring for 30 min.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrodeposition coating composition capable of forming a coating film having excellent abrasion resistance with an anodic deposition type electrodeposition coating material for coating metal products such as aluminum and iron. .

[0002]

2. Description of the Related Art Conventionally, various coatings have been performed for the purpose of preventing corrosion of metal products such as aluminum and iron, protecting the surface, and imparting aesthetic appearance. Among them, anodic deposition type electrodeposition coating is often performed because it has particularly excellent film thickness uniformity, high coating efficiency, suitability for unmanned coating, low pollution by low organic solvent content, excellent corrosion resistance and weather resistance etc. I have. However, recently, among these painted products, in fields in which the appearance of the surface is regarded as important, such as aluminum sashes and steel furniture, deterioration of the appearance due to abrasion has come to be regarded as a problem. On the other hand, the organic resin, which is one of the main components of the coating film, has a remarkably low hardness compared to inorganic substances that can cause scratches such as metal powder, sand, and abrasives. It continues to this day without any improvement in strength. Particularly, in a coating film containing no inorganic pigment, the improvement of the scratch resistance is strongly desired.

[0003]

DISCLOSURE OF THE INVENTION The present inventors have studied to incorporate a high-hardness substance, mainly an inorganic oxide, into a coating film for the purpose of improving the surface strength of the electrodeposition coating film. Reached.

[0004]

According to the present invention, there is provided a water-soluble anodic deposition type electrodeposition paint containing a polycarboxylic acid resin partially neutralized with an amine or ammonia and a curing agent. Incorporation of the compound (1) adds excellent abrasion resistance to a coating film formed from the composition. That is, the present invention is an anode deposition type electrodeposition coating composition containing colloidal silica.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The colloidal silica used in the present invention is generally known to have fine particles of silica having a particle diameter of 200 nm or less dispersed in an organic solvent such as water or alcohol. , Products of Asahi Denka Kogyo Co., Ltd. are typical examples. For example, Snowtex 20, 30, 40, N, O, U
P, Snowtex MA-ST-M, IPA-ST, E
G-ST, MEK-ST, Cataloid S-20L, S-
30L, SI-30, SI-40, SI-350, SI
-550, SN, Oscar 1132, 1332, 143
2,1632, Adelite AT-20, AT-40, A
T-50, AT-30A, AT-20Q and the like. Such colloidal silica is preferably blended so as to have a content of 1 to 60% by weight of the coating film. If the amount is less than 1% by weight, no improvement in the abrasion performance is observed, and if it exceeds 60% by weight, it becomes difficult to form a continuous coating film, which is not preferable. Particularly preferred is 5 to 40% by weight.

The water-soluble coating composition comprising a polycarboxylic acid resin partially neutralized with amine or ammonium and a curing agent for use in the present invention is disclosed, for example, in JP-A-59-17016.
Anodic deposition, such as a transparent or colored coating composition as shown in JP-A No. 4-14, JP-A-61-141771, JP-A-6-107797, and JP-A-07-292297. A type electrodeposition coating composition is used, and the resin composition and the curing agent composition are not limited. However, in particular, weather resistance, coloring suitability, chemical resistance, etc. By
It is preferable to use a curing agent capable of causing a three-dimensional crosslinking reaction with such a resin.

The acrylic polycarboxylic acid resin is
It can be obtained by copolymerizing an α, β ethylenically unsaturated carboxylic acid monomer, a hydroxyl group-containing α, β ethylenically unsaturated monomer and, if necessary, other α, β ethylenically unsaturated monomers.

Examples of the α, β ethylenically unsaturated carboxylic acid monomer include acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, itaconic acid and vinyl acetic acid. These monomers have a polycarboxylic acid resin having an acid value of 10 to 150 (preferably 30 to 80).
mgKOH / g is used. If it is less than 10, the qualitative properties of the paint are poor and precipitation is likely to occur, which is not preferable. On the other hand, if it exceeds 150, it easily dissolves in water, so that even if electrodeposition coating is performed, the deposited coating film is dissolved again in water and a uniform coating film is not formed. Further, problems such as poor alkali resistance of the coating film appear, which is not preferable.

The hydroxyl group-containing α, β ethylenically unsaturated monomers include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate,
4-hydroxybutyl (meth) acrylate and the like, and modified lactones thereof, diethylene glycol mono (meth) acrylate, triethylene glycol mono (meth) acrylate, tetraethylene glycol mono (meth) acrylate, polyethylene glycol mono (meth) acrylate, Examples include polypropylene glycol mono (meth) acrylate. These monomers are used so that the hydroxyl value of the polycarboxylic resin is 50 to 300 (preferably 50 to 200) mgKOH / g. If it is less than 50, the cross-linking reaction with the curing agent does not sufficiently occur, so that the strength, chemical resistance, solvent resistance, weather resistance and the like of the coating film are not practical and unfavorable. On the other hand, if it exceeds 300, the water resistance of the coating film is poor, which is not preferable.

Other α, β ethylenically unsaturated monomers include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, and n-butyl (meth) acrylate. A) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, 2-ethylhexyl (meth)
Alkyl esters of (meth) acrylic acid such as acrylate, acetoacetoxymethyl (meth) acrylate, acetoacetoxyethyl (meth) acrylate, (meth) acrylamido, N-methylol (meth) acrylamide, methoxymethyl (meth) acrylamide, amidates of (meth) acrylic acid such as n-butoxymethyl (meth) acrylamide, diacetone (meth) acrylamide, styrene, α-methylstyrene, vinyltoluene,
Examples thereof include vinyl monomers such as vinyl acetate and (meth) acrylonitrile, and polyfunctional monomers such as divinylbenzene, diethylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, and allyl (meth) acrylate. One or more of these can be used as needed.

The polycarboxylic acid resin of the present invention is obtained by copolymerizing the above monomers by a method such as solution polymerization, suspension polymerization, emulsion polymerization, non-aqueous dispersion polymerization and the like. Particularly, solution polymerization is preferred. At this time, an organic solvent is used as a reaction solvent if necessary. Examples of such organic solvents include alcohols such as ethanol, propanol and butanol, ether alcohols such as butoxyethanol, methoxypropanol, ethoxypropanol and butoxypropanol; ketones such as methyl ethyl ketone and methyl isobutyl ketone; and aromatic hydrocarbons such as toluene and xylene. And the like. Known polymerization initiators such as organic peroxides, azo compounds, ammonium persulfate, and potassium persulfate can be used as the polymerization initiator.

The curing agent used in the present invention generally comprises 1
When heated to 00 to 250 ° C., a curing agent for a baking-type paint is used which causes a three-dimensional crosslinking reaction with the above-mentioned polycarboxylic acid resin and cures. Among them, for example,
Particularly preferred are alkoxymethylated melamine and blocked isocyanate. Such a curing agent is preferably used in a weight ratio of 10 to 200 with respect to 100 of the above-mentioned polycarboxylic acid resin. If it is less than 10, curing is insufficient, and sufficient coating strength and coating performance cannot be obtained. If it exceeds 200, the coating becomes brittle, which is not preferable.

The amine used in the present invention is alkylamine such as monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monobutylamine, dibutylamine, tributylamine, etc., monoethanolamine, diethanolamine, dipropanolamine, dimethylethanolamine. And alkanolamines such as methyldiethanolamine, ethyldiethanolamine and triethanolamine. These are preferably used in a degree of neutralization of 10 to 100 mol% with respect to the carboxylic acid groups in the polycarboxylic acid resin. If it is less than 10, the dispersion state of the paint solids in water is unstable, and precipitation tends to occur, which is not preferable. Also 10
If it exceeds 0, the electric conductivity of the paint becomes too high,
Since gas generated by electrolysis of water during electrodeposition coating increases, traces of this gas undesirably remain as coating film defects.

The electrodeposition coating composition of the present invention is prepared by partially neutralizing the above-mentioned mixture of colloidal silica, polycarboxylic acid and a curing agent with an amine or ammonium, and adding water to dilute the mixture to a predetermined concentration. Alternatively, the polycarboxylic acid resin may be partially neutralized with amine or ammonium first and dispersed in water, and then colloidal silica and a curing agent may be added and mixed. Alternatively, colloidal silica and a curing agent may be mixed with a polycarboxylic acid resin dispersed in water in advance by emulsion polymerization or suspension polymerization. However, the present invention may be any state in which these components are dispersed in water and do not cause a problem in electrodeposition coating.
In particular, it does not limit the method for producing the coating composition.

In the present invention, an organic or inorganic coloring pigment or extender, an additive such as an antifoaming agent or a leveling agent, a curing catalyst, or the like may be used, if necessary.

[0016]

The present invention will be described below with reference to production examples and examples. The numbers represent parts by weight.

Production of Polycarboxylic Acid Resin (Preparation Example 1) (Polycarboxylic acid resin A-1) A reactor having a stirrer, a thermometer, a monomer dropping device, and a reflux cooling device is prepared. (1) ethylene glycol monobutyl ether 10.2 (2) isopropyl alcohol 40.7 (3) 2-ethylhexyl methacrylate 3.1 (4) n-butyl acrylate 26.8 (5) methyl methacrylate 29.4 (6) Styrene 13.5 (7) 2-hydroxyethyl acrylate 17.6 (8) γ-methacryloxypropyltrimethoxysilane 2.5 (9) Acrylic acid 7.1 (10) Azobisisobutyronitrile 1.0 ( 11) Azobisisobutyronitrile 0.5 Total 152.4

(1) and (2) were charged into a reactor, the temperature was raised to the reflux temperature with stirring, (3) to (10) were previously mixed uniformly, and then added dropwise over 3 hours. Temperature is 90 ±
Maintained at 3 ° C. 1.5 hours after completion of dropping, (11)
, And the reaction was further continued at 90 ± 3 ° C. for 1.5 hours, followed by cooling. Resin solids = 65%, acid value = 55 mg KO
H / g (resin solid content) transparent and viscous resin liquid A-1
I got

(Production Example 2) (Polycarboxylic acid resin A-
2) A reactor having a stirring device, a thermometer, a monomer dropping device, and a reflux cooling device was prepared. (1) ethylene glycol monobutyl ether 25.0 (2) isopropanol 50.0 (3) n-butyl acrylate 15.6 (4) methyl methacrylate 25.6 (5) styrene 30.0 (6) 2-hydroxyethyl acrylate 20.0 (7) Acetoacetoxyethyl methacrylate 2.4 (8) Acrylic acid 6.4 (9) Azobisisobutyronitrile 1.0 (10) Azobisisobutyronitrile 0.2 Total 176.2 ( 1) was charged into a reactor, the temperature was raised to 90 ° C. with stirring, (2) to (9) were previously mixed uniformly, and then added dropwise over 3 hours. The temperature at this time was maintained at 90 ± 3 ° C. 1.5 hours after the completion of the dropwise addition, (10) was added, and the reaction was further continued at 90 ± 3 ° C. for 1.5 hours. After cooling, the resin solid content was 56% and the acid value was 50 mgKOH / g (resin solid content equivalent). )) And a viscous resin liquid A-2 was obtained.

Production Example of Electrodeposition Coating Composition (Production Example 3) Electrodeposition coating composition B-1 (1) Polycarboxylic acid A-1 152.4 (2) Triethylamine 7.2 (3) Deionized water 160 0.0 (4) Nikarac MX-40 50.0 (Melamine manufactured by Sanwa Chemical Co., Ltd.) (5) Deionized water 1690.0 (6) Snowtex UP (NV = 20%) 321.5 (Nissan Chemical's colloidal silica) ) Into 2381.1 (1), add (2) and (3) with stirring, stir for 1 hour until uniform, and then add (4). Then 80
After the temperature was raised to 0 ° C and the mixture was stirred for 2 hours, it was cooled to 25 ° C. Subsequently, (5) and (6) were added, and the mixture was stirred and mixed for 30 minutes.
An electrodeposition coating composition B-1 of 0 Ω · cm was obtained.

(Production Example 4) Electrodeposition coating composition B-2 (1) Polycarboxylic acid A-2 176.2 (2) Snowtex IPA-ST (NV = 30%) 88.3 (manufactured by Nissan Chemical Industries, Ltd.) (Silica sol) (3) Triethylamine 7.2 (4) Deionized water 106.6 (5) Cymel 238 (Melamine manufactured by Mitsui Cytec) 50.0 (6) 35% aqueous formaldehyde solution 0.4 (7) Deionized water 1532. 4 A total of 1961.1 (1) was charged with (2), (3), (4), and (5) under stirring, and stirred for 1 hour until the mixture became uniform. Next, (6) was charged, the temperature was raised to 80 ° C., and the temperature was kept for 2 hours. Thereafter, the mixture was cooled to 25 ° C., (7) was added thereto, and the mixture was stirred and mixed for 30 minutes. Solid content = 9%, PH = 8.9, liquid specific resistance = 1.
An electrodeposition coating composition B-2 of 750 Ω · cm was obtained.

(Production Example 5) Electrodeposition coating composition B-3 (Example not containing colloidal silica) (1) Polycarboxylic acid A-1 152.4 (2) Triethylamine 7.2 (3) Deionized water 160 0.0 (4) Nikarac MX-40 (Melamine manufactured by Sanwa Chemical Co., Ltd.) 50.0 (5) Deionized water 1297.1 Total 1666.7 (2) and (3) were added to (1) with stirring. After stirring for 1 hour until the mixture becomes uniform, (4) is charged. Then 80
After the temperature was raised to 0 ° C and the mixture was stirred for 2 hours, it was cooled to 25 ° C. Subsequently, (5) was added, and the mixture was stirred and mixed for 30 minutes. Solid content = 9%, PH = 9.1, liquid specific resistance = 1800 Ω · c.
m of the electrodeposition coating composition B-3 was obtained.

(Production Example 6) Electrodeposition coating composition B-4 (Example not containing colloidal silica) (1) Polycarboxylic acid A-2 176.2 (2) Triethylamine 7.2 (3) Deionized water 160 0.0 (4) Cymel 238 (Melamine manufactured by Mitsui Cytec) 30.0 (5) 35% aqueous formaldehyde solution 0.4 (6) Deionized water 1297.1 Total 1670.9 (1) under stirring with (2), (3) and (4) were added, and the mixture was stirred for 1 hour until the mixture became uniform. Next, input (5),
The temperature was raised to 80 ° C. and kept for 2 hours. Then 25
C., added (6), stirred and mixed for 30 minutes, solid content = 9%, PH = 9.0, liquid specific resistance = 1810
Ω · cm of the electrodeposition coating composition B-4 was obtained.

Examples 1 and 2 Comparative Examples 1 and 2 The electrodeposition coating compositions described in the Production Examples were placed in a 3 liter PVC tank, and the cathode was made of SUS304 steel plate.
Alumite treatment on 3S aluminum alloy plate (alumite film thickness =
9 μm), and further subjected to electrolytic coloring in black, and then subjected to electrodeposition coating using a material washed with hot water by an ordinary method as an anode (object to be coated). Subsequently, after baking was performed at 180 ° C. for 30 minutes, the coating film performance was evaluated. The results are shown in Tables 1 and 2.

[0025]

[Table 1]

[0026]

[Table 2]

(Note) Evaluation method (1) Gloss: 60 ° gloss was measured with a gloss meter. (2) Scratch resistance: A corrugated paper was loaded with a load of 10 g / square cm, and the degree of scratching after visually rubbing the coated plate for 50 reciprocations with a 5 cm stroke was evaluated visually. ○ = Scratch is not visible. Δ = Scratch is visible, but not so white as a sheet. × = The scar looks like a white surface. (3) Vickers hardness: Fisher scope H-10
Measured at 0. The lowest value measured when increasing the load from 0 to 256 mN was defined as hardness. (4) Alkali resistance: After immersion in 1% NaOH at 20 ° C. for 48 H, the state of the coated surface was observed. (5) Acid resistance: After immersing for 48 hours in 5% sulfuric acid at 20 ° C., the state of the coated surface was observed.

[0028]

The coating composition of the present invention comprises an aluminum sash,
By coating metal parts such as steel furniture and home appliances, excellent scratch resistance can be imparted to these surfaces.

 ──────────────────────────────────────────────────の Continued from the front page (72) Eiji Masuda, Inventor 6-10-73 Minamitsukaguchi-cho, Amagasaki City, Hyogo Prefecture Inside Shinto Paint Co., Ltd.

Claims (1)

[Claims] 1. An electrodeposition type electrodeposition coating composition comprising colloidal silica.